WO2007069866A1

WO2007069866A1 - Fluid pump

Info

Publication number: WO2007069866A1
Application number: PCT/KR2006/005495
Authority: WO
Inventors: Kyung-Yul Hyun
Original assignee: Kyung-Yul Hyun
Priority date: 2005-12-16
Filing date: 2006-12-15
Publication date: 2007-06-21

Abstract

A fluid pump for a compressor according to the present invention comprises a rotating chamber formed by first and second opposing wall surfaces and a third cylindrical wall surface for connecting the first and second wall surfaces to each other; a rotating body including a rotational shaft rotating about a rotation axis, and a cam wall that protrudes radially outwardly from an outer surface of the rotational shaft and includes a first contacting portion, a second contacting portion, and an inclined portion for connecting the first and second contacting portions to each other; and a pair of cam follower walls interacting with the cam wall and moving linearly according to rotation of the rotating body, wherein each of the first and second wall surfaces is formed with an inflow passage and a discharge passage that communicate with a space where the cam wall is placed in the rotating chamber and are provided respectively at both sides of the cam follower wall, a communicating passage is provided to cause the discharge passage of the first wall surface to communicate with the inflow passage of the second wall surface, the space where the cam wall is placed in the rotating chamber is divided into a first space capable of communicating with the passages formed in the first wall surface and a second space capable of communicating with the passages formed in the second wall surface by the cam wall, and the first space is larger than the second space.

Description

FLUID PUMP

Technical field The present invention relates to a fluid pump, and more particularly, to a rotary fluid pump.

Background Art

A fluid pump is a device that sucks a fluid and discharges the sucked fluid to the outside through rotation of a rotational shaft thereof by a driving device, and the fluid pump also serves as a compressor. Conventional rotary pumps are classified into a vane type fluid pump with vanes which slidably move, a gear type fluid pump with two gears engaged with each other, a screw type fluid pump having male and female screws engaged with each other, and the like. The vane type fluid pump is widely used due to an advantage of a relatively simple structure. However, since the vane type fluid pump should be configured such that vanes can come in and out of a rotor, its structure becomes further complicated in a case where the vane pump is used as a two-stage compressor. In addition, there are structural problems in that vibration may be produced in the vane type fluid pump because its rotational shaft is eccentric, and that bearings may be easily damaged due to an unbalanced load applied to the rotational shaft. In addition, the fluid is not discharged continuously, resulting in generation of pulsation.

Disclosure of Invention

Technical Problem An object of the present invention is to provide a rotary fluid pump having a non-eccentric structure. Another object of the present invention is to provide a rotary fluid pump having a simpler structure in which vanes do not come in and out of a rotor. A further object of the present invention is to provide a fluid pump having reduced wear in contacting portions. A still further object of the present invention is to provide a fluid pump capable of variously adjusting a discharge rate according to discharge pressure. A still further object of the present invention is to provide a compressor capable of adjusting pressure.

Technical Solution According to the present invention, a fluid pump for a compressor comprises a rotating chamber formed by first and second opposing wall surfaces and a third cylindrical wall surface for connecting the first and second wall surfaces to each other; a rotating body including a rotational shaft rotating about a rotation axis passing centers of the first and second wall surfaces, and a cam wall protruding radially outwardly from an outer surface of the rotational shaft so that an end of the cam wall can be slidably in close contact with the third wall surface of the rotating chamber, wherein the cam wall includes a first contacting portion slidably brought into close contact with the first wall surface of the rotating chamber, a second contacting portion slidably brought into close contact with the second wall surface, and an inclined portion for connecting the first and second contacting portions to each other; and a pair of cam follower walls interacting with the cam wall and moving linearly according to rotation of the rotating body, wherein the cam follower walls are disposed such that a corner of one of the cam follower walls faces a corner of the other one of the cam follower walls, the opposing corners of the cam follower walls are slidably in contact with both surfaces of the cam wall, and other corners adjacent to the opposing corners are slidably in contact with the outer surfaces of the rotational shaft of the rotating body. The first wall surface is formed with an inflow passage and a discharge passage that communicate with a space where the cam wall is placed in the rotating chamber and are provided respectively at both sides of the cam follower wall. The second wall surface is formed with an inflow passage and a discharge passage that communicate with the space where the cam wall is placed in the rotating chamber and are provided respectively at both sides of the cam follower wall. A communicating passage is provided to cause the discharge passage of the first wall surface to communicate with the inflow passage of the second wall surface. The space where the cam wall is placed in the rotating chamber is divided into a first space capable of communicating with the passages formed in the first wall surface and a second space capable of communicating with the passages formed in the second wall surface by the cam wall. The first space is larger than the second space.

The fluid pump may further comprise a first gas chamber placed on the side of the first wall surface of the rotating chamber; a second gas chamber placed on the side of the second wall surface of the rotating chamber; a first contacting member separating the rotating chamber and the first gas chamber, wherein the first contacting member is formed with the first wall surface to come into contact with the first contacting portion of the cam wall and has a first contacting wall provided with the inflow passage and the discharge passage; and a second contacting member separating the rotating chamber and the second gas chamber, wherein the second contacting member is formed with the second wall surface to come into contact with the second contacting portion of the cam wall and has a second contacting wall provided with the inflow passage and the discharge passage. The first contacting member may have a division wall extending from the first contacting wall to divide the first gas chamber into spaces communicating with the inflow passage and the discharge passage of the first contacting wall in one-to-one correspondence. The second contacting member may have a division wall extending from the second contacting wall to divide the second gas chamber into spaces communicating with the inflow passage and the discharge passage of the second contacting wall in one-to-one correspondence. The space of the first gas chamber communicating with the inflow passage of the first contacting wall may communicate with a suction port through which gas is sucked, and the space of the second gas chamber communicating with the discharge passage of the second contacting wall may communicate with a discharge port through which gas is discharged.

In the fluid pump, the first contacting portion of the cam wall may have a radial width smaller than that of the second contacting portion.

In the fluid pump, the cam wall may have a constant thickness in a direction of the rotation axis, and the pair of cam follower walls may be integrated with each other to form a cam follower wall body.

In the fluid pump, the cam follower wall body may have a contacting portion to come into contact with a radial end of the cam wall, and the contacting portion may be provided with a groove recessed radially outwardly.

The fluid pump may further comprise a guide groove enabling a radial movement of the cam follower wall body, and a pressure adjusting unit for adjusting a radial position of the cam follower wall body. In the fluid pump, the pressure adjusting unit may comprise a cylinder; a moving member coupled to the cam follower wall body and provided with a piston that is received in the cylinder and can move in a radial direction; an elastic member for pushing the piston radially inwardly; and a discharge pressure communicating passages for supplying pressure of discharged gas into the cylinder so as to provide pressure used for pushing the piston radially outwardly.

In the fluid pump, the cam wall may be provided with two first contacting portions, two second contacting portions, two cam follower wall bodies, two guide grooves and two pressure adjusting units.

In the fluid pump, one of the elastic members of the two pressure adjusting units may provide an elastic force larger than that of the other of the elastic members of the pressure adjusting units.

In the fluid pump, the first contacting portion of the cam wall may have a thickness in a direction of the rotation axis that is larger than that of the second contacting portion. In the fluid pump, the cam wall may have two first contacting portions, two second contacting portions and two pairs of cam follower walls.

The fluid pump may further comprise an elastic member for pushing the cam follower wall toward the cam wall.

According to another aspect of the present invention, a fluid pump comprises a first rotating body including a first rotor extending along a rotation axis and a first cam wall protruding from the first rotor radially outwardly with respect to the rotation axis, wherein the first cam wall extends in a circumferential direction about the rotation axis so as to surround the first rotor; a second rotating body including a second rotor extending along the rotation axis and a second cam wall protruding from the second rotor radially outwardly with respect to the rotation axis, wherein the second cam wall extends in the circumferential direction about the rotation axis so as to surround the second rotor; a first fluid chamber in which the first cam wall of the first rotating body is received and which is divided into a plurality of spaces by the first cam wall; a second fluid chamber in which the second cam wall of the second rotating body is received and which is divided into a plurality of spaces by the second cam wall; a pair of first cam follower walls interacting with both surfaces of the first cam wall; and a pair of second cam follower walls interacting with the second cam wall. Each of the fluid chambers is formed by a first wall surface and a second surface perpendicular to the rotation axis, a third wall surface that is an outer peripheral surface of each of the rotors, and a fourth wall surface slidably in contact with a radial end of each of the cam walls. Each of the cam walls is provided with a first contacting portion slidably in contact with the first wall surface of the fluid chamber in which the cam wall is received, a second contacting portion slidably in contact with the second wall surface of the fluid chamber in which the cam wall is received, and an inclined portion connecting the first contacting portion and the second contacting portion and inclined with respect to a circumferential extension line of the rotation axis. One corner of one cam follower wall of each pair of cam follower walls faces one corner of the other cam follower wall of the pair of cam follower walls, the opposing corners of the cam follower walls are slidably in contact with both surfaces of the cam wall interacting with the corners, the other corners are slidably in contact with the third wall surface of the fluid chamber, and the pair of cam follower walls linearly moves according to rotation of the cam wall interacting therewith. The two cam walls are formed such that the pair of first cam follower walls and the pair of second cam follower walls simultaneously move toward each other or far away from each other. Each of the first and second fluid chambers has a suction port and a discharge port provided on both sides of the pair of cam follower walls.

In the fluid pump, each of the fluid chambers may have a suction communicating groove and a discharge communicating groove formed on both sides of the pair of cam follower walls, the suction communicating groove and the discharge communicating groove may extend from the first wall surface to the second wall surface to cause both spaces with the received cam wall interposed therebetween to communicate with each other, the suction communicating groove may communicate with a suction port through which a fluid is sucked, the discharge communicating groove may communicate with a discharge port through which the fluid is discharged, and the first and second contacting portions of each of the cam walls may be formed such that the suction communicating groove and the discharge communicating groove can simultaneously enter a distal section at a certain position as the cam wall is rotated.

The fluid pump may further comprise a first communicating passage for causing the suction port of the first fluid chamber to communicate with the suction ^"port of the second fluid chamber, and a second communicating passage for causing the discharge port of the first fluid chamber to communicate with the discharge port of the second fluid chamber.

The fluid pump may further comprise a discharge rate-adjusting unit including a control unit which has a communicating port communicating with the first communicating passage, an inflow port communicating with the first communicating passage, and a discharge port and causes the inflow port to communicate with the discharge port or the communicating port to communicate with the inflow port according to pressure in the discharge port.

In the fluid pump, the control unit may comprise a first room provided with the communicating port, the inflow port and the discharge port; a second room communicating with the discharge port; a moving member provided moveably in the first room and subjected to pressure from the second room; and an elastic member for pushing the moving member in a direction resisting the pressure of the second room, and the moving member may have a division wall for dividing the first room into a space communicating with the communicating port and a space communicating with the discharge port.

In the fluid pump, the first cam wall may have two first contacting portions, two second contacting portions, and two pairs of first cam follower walls, and the suction communicating groove and the discharge communication groove may be provided on both sides of each of the pairs of first cam follower walls. The second cam wall may have two first contacting portions, two second contacting portions, and two pairs of second cam follower walls, and the suction communicating groove and the discharge communication groove may be provided on both sides of each of the pairs of second cam follower walls. Two suction communicating grooves and two discharge communication grooves may be provided. The discharge rate-adjusting unit may have two control units, and the discharge ports of the two control units communicate with each other.

In the fluid pump, the second spaces of the two control units of the discharge rate-adjusting unit may be formed into a single space.

In the fluid pump, the first cam wall may have two first contacting portions, two second contacting portions, and two pairs of first cam follower walls, and the suction communicating groove and the discharge communication groove may be provided on both sides of each of the pairs of first cam follower walls. The second cam wall may have two first contacting portions, two second contacting portions, and two pairs of second cam follower wall pairs, and the suction communicating groove and the discharge communication groove may be provided on both sides of each of the pairs of second cam follower walls. Two suction communicating grooves and two discharge communication grooves may be provided. The fluid pump may further comprise a discharge rate- adjusting unit including a control unit which has a communicating port communicating with the first communicating passage or the second communicating passage, two inflow ports communicating with the two second communicating passages, and a discharge port and causes at least one of the two inflow ports to communicate with the discharge port or the communicating port to communicate with the two inflow ports according to pressure in the discharge port.

In the fluid pump, the control unit may comprise a first room provided with the communicating port, the two inflow ports and the discharge port; a second room communicating with the discharge port; a moving member provided moveably in the first room and subjected to pressure from the second room; and an elastic member for pushing the moving member in a direction resisting the pressure of the second room, and the moving member may have a division wall for dividing the first room into a space communicating with the communicating port and a space communicating with the discharge port. The fluid pump may further comprise a communicating passage for causing the discharge port of the first fluid chamber to communicate with the suction port of the second fluid chamber.

In the fluid pump, the first rotor of the first rotating body and the second rotor of the second rotating body may be formed integrally with each other.

The fluid pump may further comprise an intermediate member surrounding the rotor between the first cam wall and the second cam wall. The intermediate member may have both ends forming the first wall surface or the second wall surface of the first and second fluid chambers, and may be divided into two parts by a separating surface passing the both ends thereof.

In the fluid pump, a radial end of each of the cam walls may be provided with a vane that is movable radially outwardly.

In the fluid pump, the vane may connect a first contacting portion of the cam wall to a second contacting portion adjacent to the first contacting portion. In the fluid pump, the vane may extend along the circumferential direction about the rotation axis.

In the fluid pump, two separate vanes may be provided.

Advantageous Effects According to the constitution of the present invention, all the objects of the present invention can be achieved. Specifically, since the rotor is not eccentric, vibration is not generated. Contrary to a conventional vane type pump, the structure of the pump becomes simpler since the vanes do not come in and out of the rotor. Further, since a groove is provided in a contacting portion, wear is reduced in the contacting portion. Moreover, since two-stage compression is performed in one rotating chamber, the structure of the pump is simplified. Furthermore, pressure can be adjusted due to the presence of a pressure adjusting unit. In addition, since two symmetrical cam walls are provided, eccentricity is not generated. Further, since a discharge rate-adjusting unit is provided, the discharge rate can be variously adjusted according to discharge pressure. Description of Drawings

Fig. 1 is a perspective view of a fluid pump used as a two-stage compressor according to an embodiment of the present invention, in which a housing is partially cutaway to illustrate the interior thereof. Fig. 2 is an exploded perspective view of the compressor shown in Fig. 1.

Fig. 3 is a side view of the compressor shown in Fig. 1, in which the housing is cut to illustrate the interior thereof.

Fig. 4 is a view showing the interior of a rotating chamber, in which the housing of the compressor shown in Fig. 1 is cut perpendicularly with respect to a rotational shaft. Fig. 5 is a perspective view showing an opposite end of the housing of the compressor shown in Fig. 2.

Fig. 6 is a perspective view showing an assembled state of other members except for the housing in the compressor shown in Fig. 1.

Figs. 7 (a) and (b) are perspective views of a first contacting member of the compressor shown in Fig. 1.

Fig. 8 is a perspective view of a linear moving body of the compressor shown in Fig. 3.

Fig. 9 is a view showing a deployed state of a cam wall of the compressor shown in Fig. 1, simultaneously showing first and second contacting members, and respective cam follower walls of first and second linear moving bodies.

Figs. 10 and 11 are views showing the interior of the rotating chamber, in which the housing of the compressor shown in Fig. 1 is cut perpendicularly with respect to a rotational shaft.

Fig. 12 is a perspective view of a fluid pump used as a two-stage compressor according to a second embodiment of the present invention, in which a housing is partially cut-away to illustrate the interior thereof.

Fig. 13 is a side view of the compressor shown in Fig. 12, in which the housing is cut to illustrate the interior thereof.

Fig. 14 is a view showing a deployed state of a cam wall of the compressor shown in Fig. 1, simultaneously showing first and second contacting members, and respective cam follower walls of first and second linear moving bodies.

Fig. 15 is a perspective view of a fluid pump according to a third embodiment of the present invention.

Fig. 16 is an exploded perspective view of the fluid pump shown in Fig. 15. Fig. 17 is a side view of the fluid pump of Fig. 15, in which a housing is cut along line A-A' to illustrate the interior thereof.

Fig. 18 is a plan view of the fluid pump shown in Fig. 15, in which the housing is cut along line B-B' to illustrate the interior thereof.

Fig. 19 is a sectional view showing the interior of the housing of the fluid pump shown in Fig. 15, in which the housing is cut perpendicularly to a rotational shaft.

Fig. 20 is a deployed view showing the interior of the fluid pump shown in Fig. 15.

Fig. 21 is a perspective view showing another embodiment of a cam wall shown in Fig. 16. Fig. 22 is a deployed view showing the interior of a fluid pump according to a fourth embodiment of the present invention.

Fig. 23 is a view showing another embodiment of the fluid pump shown in Fig. 15, in which a discharge rate-adjusting unit is independently installed.

Figs. 24 (a) to (c) are views showing another embodiment of the discharge rate- adjusting unit of the fluid pump shown in Fig. 15 in accordance with operating states thereof.

Best Mode

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to Figs. 1 to 4, a fluid pump compressor 10 comprises a housing 20, first and second pressure adjusting units 90 and 95, a rotating body 30 that rotates about a rotation axis 100, first and second linear moving bodies 50 and 60, and first and second contacting members 70 and 80. The housing 20 includes first and second end walls 22 and 24, and a sidewall 26 for connecting the two end walls 22 and 24 to each other. Each of the first and second end walls 22 and 24 is a disk member and is perpendicular to the rotation axis 100. The first and second end walls are coupled to both ends of the sidewall 26 so that the two end walls face each other. First and second suction ports 221 and 222 are provided in the first end wall 22, and first and second discharge ports 241 and 242 are provided in the second end wall 24. The first suction port 221 and the second suction port 222 communicate with space IA (211 in Fig. 9) and space 1C (213 in Fig. 9) of a first gas chamber 21 respectively, which will be described later. The first discharge port 241 and the second discharge port 242 communicate with space 2D (254 in Fig. 9) and space 2B (252 in Fig. 9) of a second gas chamber 25 respectively, which will be described later. The sidewall 26 is a hollow cylindrical member with both open ends that are to be closed by the first and second end walls 22 and 24 coupled thereto. The housing 20 has a cylindrical space defined therein, and this space is divided into the first gas chamber 21, a rotating chamber 23 and the second gas chamber 25 by a contacting wall 71 of the first contacting member 70 and a contacting wall 81 of the second contacting member 80. The first and second contacting walls that will be described later are disposed in order from the first end wall 22 along the rotation axis 100. The first gas chamber 21 is a space formed between the first end wall 22 and the contacting wall 71 of the first contacting member 70, which will be described later. Referring to Fig. 9, the first gas chamber 21 is divided into space IA 211, space IB 212, space 1C 213 and space ID 214 which are disposed in a circumferential direction and isolated from one another by first, second, third and fourth division walls 75, 76, 77 and 78 of the first contacting member 70 that will be described later. Space IA 211 and space 1C 213 communicate with the first suction port 221 and the second suction port 222 formed in the first end wall 22, respectively. Gas is sucked into the compressor 10 through the two suction ports 221 and 222. The rotating chamber 23 is a space formed between the contacting wall 71 of the first contacting member 70 and the contacting wall 81 of the second contacting member 80. The rotating chamber 23 is defined by first and second wall surfaces 231 and 232, which are in the form of disks and face each other, and a third wall surface 233 that is in the form of a cylinder and connects the first and second wall surfaces 231 and 232 to each other. The first and second wall surfaces 231 and 232 are surfaces opposite to the contacting wall 71 of the first contacting member 70 and the contacting wall 81 of the second contacting member 80, respectively. The third wall surface 233 becomes a portion between the contacting wall 71 of the first contacting member 70 and the contacting wall 81 of the second contacting member 80 inside the sidewall 26 of the housing 20. Two first contacting portions 341 and 345 of a cam wall 34 of the rotating body 30, which will be described later, are slidably in close surface- contact with the first wall surface 231, and two second contacting portions 343 and 347 of the cam wall 34 are slidably in close surface-contact with the second wall surface 232. A radial end 3491 of the cam wall 34 is slidably in close contact with the third wall surface 233. The second gas chamber 25 is a space formed between the second end wall 24 and the contacting wall 81 of the second contacting member 80. The second gas chamber 25 is divided into space 2A 251, space 2B 252, space 2C 253 and space 2D 254 which are disposed in the circumferential direction and isolated from one another by first, second, third and fourth division walls 85, 86, 87 and 88 of the second contacting member 80 that will be described later. Space 2B 252 and space 2D 254 communicate with the first and second discharge ports 241 and 242 formed in the second end wall 24, respectively. Gas is discharged out of the compressor 10 through the two discharge ports 241 and 242.

Referring to Figs. 1 to 5, a first guide groove 365 and a second guide groove 266 are formed in the third wall surface 233 of the rotating chamber 23 such that the guide grooves are disposed at positions symmetrical about the rotation axis 100 and extend in parallel with the rotation axis 100. Base portions 52 and 62 of the first and second linear moving bodies 50 and 60 that will be described later are fitted into the two guide grooves 265 and 266, respectively, such that the base portions can be slid in a direction parallel with the rotation axis 100. Further, the depth of each of the guide grooves 265 and 266 is determined such that the two linear moving bodies 50 and 60 can move in a radial direction with respect to the rotation axis 100. The housing 20 is provided with a first communicating passage 200 through which space ID 214 of the first gas chamber 21 communicates with space 2A 251 of the second gas chamber 25, and a second communicating passage 205 through which space IB 212 of the first gas chamber 21 communicates with space 2C 253 of the second gas chamber 25. The first communicating passage 200 is formed by a first through-hole 201 for connecting both ends of the sidewall 26 of the housing 20, and first and second communicating grooves 202 and 203 formed at both ends of the sidewall 26 of the housing 200 to cause space ID 214 of the first gas chamber 21 and space 2A 251 of the second gas chamber 25 to communicate with both ends of the first through-hole 201, respectively. The second communicating passage 205 is formed by a second through-hole 206 for connecting both ends of the sidewall 26 of the housing 20, and third and fourth communicating grooves 207 and 208 formed at both ends of the sidewall 26 of the housing 200 to cause space IB 212 of the first gas chamber 21 and space 2C 253 of the second gas chamber 25 to communicate with both ends of the second through-hole 206, respectively. However, the present invention does not intend to limit the structures of the first and second communicating passages thereto. So far as space ID 214 of the first gas chamber 21 can communicate with space 2A 251 of the second gas chamber 25 and space IB 212 of the first gas chamber 21 can communicate with space 2C 253 of the second gas chamber 25, the structure can be modified into any other structures and the present invention includes all of these structures.

Referring to Figs. 1 to 3, first and second bearings 42 and 44 are provided at centers of the first and second end walls 22 and 24 of the housing 20, respectively. A rotational shaft 40 that will be described below and extends along the rotation axis 100 is rotatably supported by the first and second bearings 42 and 44. The rotational shaft 40 extends out of the second end wall 22 along the rotation axis 100 and is coupled to and rotated by a driving device (not shown). The first suction port 221 and the second suction port 222 are provided in the first end wall 22 an interval of about 180° in a circumferential direction. Referring to Fig. 9 together with Figs. 1 to 3, the first suction port 221 communicates with space IA 211 of the first gas chamber 21, and the second suction port 222 communicates with space 1C 213 of the first gas chamber 21. The first discharge port 241 and the second discharge port 242 are provided in the second end wall 24 at an interval of about 180° in the circumferential direction. The first discharge port 241 communicates with space 2D 251 of the second gas chamber 25, and the second discharge port 242 communicates with space 2B 252 of the second gas chamber 25. A suction tube (not shown) and a discharge tube (not shown) through which gas passes are connected to the suction ports 221 and 222 of the first end wall 22 and the discharge ports 241 and 242 of the second end wall 24. Referring to Figs. 1 to 4, both the first and second pressure adjusting units 90 and 95 are provided in the housing 20. The first pressure adjusting unit 90 comprises a cylinder 91, a moving member 92, an elastic member 93 and a discharge pressure communicating structure 94. A receiving space 911 formed in the cylinder 91 extends in the radial direction with respect to the rotation axis 100. A through-hole 901 is provided in the sidewall 26 of the housing 20 such that the through-hole extends in the radial direction with respect to the rotation axis 100 and causes the first guide groove 265 to communicate with the receiving space 911 of the cylinder 91. An extension 922 of the moving member 92 that will be described later is slidably inserted into the through- hole 901. The receiving space 911 of the cylinder 91 is divided into a radially outer space 912 that is located radially outside and has the elastic member 93 installed therein, and a radially inner space 913 communicating with the through-hole 901 by a piston 921 of the moving member 92 that will be described later. The moving member 92 has the piston 921 and the elongated extension 922 extending from the piston 921. The piston

921 moves in the receiving space 911 of the cylinder 91 in the radial direction with respect to the rotation axis 100. The extension 922 extends from the piston 921 radially inwardly with respect to the rotation axis 100 and has a rounded end. The extension

922 is slidably inserted into the through-hole 921. The end of the extension 922 is slidably in contact with a radially outer end of the first linear moving body 50. The elastic member 93 is installed in the radially outer space 912 so as to push the moving member 92 in a radially inward direction. The discharge pressure communicating structure 94 is formed by a passage hole 941 for causing the radially inner space 913 of the receiving space 911 to communicate with one end of the sidewall 26 contacted with the second end wall 24 of the housing 20, and a communicating groove 942 for causing the passage hole 941 to communicate with space 2D 254 of the second gas chamber 25. However, the present invention does not intend to limit the structure of the discharge pressure communicating structure 94 thereto. Discharge pressure is transmitted to the radially inner space 913 of the receiving space 911 by the discharge pressure communicating structure 94. The second pressure adjusting unit 95 has the substantially same configuration as that of the first pressure adjusting unit 90 but is different from the first pressure adjusting unit 90 in that an elastic member 98 of the second pressure adjusting unit pushes a moving member 97 with a force larger than that generated by the elastic member 93 of the first pressure adjusting unit 90, in that the moving member 97 interacts with the second linear moving body 60, and in that a discharge pressure communicating structure 99 causes space 2B 252 of the second gas chamber 25 to communicate with a radially inner space 963 of a receiving space 961.

Referring to Figs. 1 to 4, the rotating body 30 comprises the rotational shaft 40 and the cam wall 34 extending to protrude radially from the rotational shaft 40. The rotational shaft 40 extends along the rotation axis 100 and is rotatably supported by the two bearings 42 and 44 provided at the two end walls 22 and 24 of the housing 20, respectively. The rotational shaft 40 extends out of the first end wall 22 along the rotation axis 100 and coupled to and rotated by the driving device (not shown).

Referring to Figs. 2 to 4, the cam wall 34 takes the shape of a wall protruding radially from an outer surface 41 of the rotational shaft 40, and surrounds the outer surface 41 of the rotational shaft 40 such that both surfaces 340 and 349 are oriented to the first wall surface 231 and the second wall surface 232 of the rotating chamber 23, respectively. One of the both surfaces 340 and 349 of the cam wall 34, which faces the first wall surface 231 of the rotating chamber 23, is herein referred to as the first surface 340 and the other surface thereof facing the second wall surface 232 of the rotating chamber 23 is referred to as the second surface 349. Referring to Fig. 9 showing a deployed state of the cam wall 34, the cam wall 34 comprises two first contacting portions 341 and 345 which are symmetrical with each other about the rotation axis and have flat surfaces having proper widths (angular widths) perpendicular to the rotation axis 100 so as to be slidably in surface contact with the first wall surface 231 of the rotating chamber 23, two second contacting portions 343 and 347 which are symmetrical with each other about the rotation axis and have flat surfaces having proper widths (angular widths) perpendicular to the rotation axis 100 so as to be slidably in surface contact with the second wall surface 232 of the rotating chamber 23, and four inclined portions 342, 344, 346 and 348 that are inclined with respect to the rotation axis 100 and connect the first contacting portions 341 and 345 to the second contacting portions 343 and 347. The cam wall 34 is formed by smoothly connecting the first contacting portion 341 - the inclined portion 342 - the second contacting portion 343 - the inclined portion 344 - the first contacting portion 345 - the inclined portion 346 - the second contacting portion 347 - the inclined portion 348 in this order in the circumferential direction about the rotation axis 100. The radial end 3491 of the cam wall 34 with respect to the rotation axis 100 is slidably in close contact with the third wall surface 233 of the rotating chamber 23. The width of each of the second contacting portions 343 and 347 is larger than that of each of the first contacting portions 341 and 345. Both opposite ends of two cam follower walls 54 and 56 of the first linear moving body 50, which will be described later, are slidably in contact with both surfaces 340 and 349 of the cam wall 34, respectively. The thickness of the cam wall 34 is determined such that the two opposite ends of the two cam follower walls 54 and 56 of the first linear moving body 50 are always movably in contact with the both surfaces 340 and 349 as the rotating body 30 is rotated. That is, the thickness of the cam wall 34 is determined such that a distance between the first surface 340 and the second surface 349 in a direction in which the first and second linear moving bodies 50 and 60 extend is maintained constant.

Referring to Fig. 9, due to the shape of the cam wall 34 described above, a space of the rotational body 30 formed between the outer surface 401 of the rotational shaft 40 and the third wall surface 233 of the rotating chamber 23 is divided into first and third spaces 11 and 13 provided by the first wall surface 231 of the rotating chamber 23 and the first surface 340 of the cam wall 34, and second and fourth spaces 12 and 14 provided by the second wall surface 232 of the rotating chamber 23 and the second surface 349 of the cam wall 34. The first and third spaces 11 and 13 are larger than the second and fourth spaces 12 and 14. Referring to Figs. 2 to 4 and 8, the first linear moving body 50 takes the shape of a generally elongated, thin linear rod, and has the base portion 52 located radially outside the rotation axis 100, and the first and second cam follower walls 54 and 56 standing radially inside the rotation axis 100 from the base portion 52. The height of the base portion 52 is smaller than the depth of the first guide groove 365 of the housing 20 into which the base portion 52 is inserted. The first cam follower wall 54 and the second cam follower wall 56 form the pair of cam follower walls. The heights of the first cam follower wall 54 and the second cam follower wall 56 are the same as that of the cam wall 34 of the rotating body 30. Radially inner end surfaces 541 and 561 of the first and second cam follower walls 54 and 56 with respect to the rotation axis 100 are slidably in close contact with the outer surface 41 of the rotational shaft 40. To this end, each of the radially inner end surfaces 541 and 561 of the first and second cam follower walls 54 and 56 takes the shape of a concave arc. The both opposite ends of the two cam follower walls 54 and 56 are slidably in close contact with the both surfaces 340 and 349 of the cam wall 34. The first cam follower wall 54 is slidably received in a first guide passage 72 of the first contacting member 70, which will be described later. The second cam follower wall 56 is slidably received in a first guide passage 82 of the second contacting member 80 to be described later. The first cam follower wall 54 and the second cam follower wall 56 are integrated by the base portion 52 to form a cam follower wall body. A radially inner end 53 of the base portion 52 connecting the first cam follower wall 54 to the second cam follower wall 56 is slidably in close contact with the radial end 3491 of the cam wall 34. A separating groove 521 is provided at a middle portion of the radial inner end 53 of the base portion 52 to prevent contact of the radial inner end of the base portion with the radial end 3491 of the cam wall 34. Since a portion of the radial end 3491 of the cam wall 34 does not come into contact with the radially inner end 53 of the base portion 52 by means of the separating groove 521, it is possible to reduce wear caused by friction. This prolongs the lifetime of the compressor 10. The first linear moving body 50 linearly moves in a direction parallel with the rotation axis 100 by the cam wall 34 in response to the rotation of the rotating body 30 while being received in the first guide groove 265 of the housing 20 and the first guide passages 72 and 82 of the first and second contacting members 70 and 80. Since the second linear moving body 60 is symmetrical with the first linear moving body 50 in their structures about the rotation axis 100 and is received in the second guide groove 266 of the housing 20 and second guide passages 74 and 84 of the first and second contacting members 70 and 80, a detailed description thereof will be omitted. As illustrated in Fig. 9 showing the deployed state of the cam wall 34, in a case where the first and second linear moving bodies (50 and 60 in Fig. 2) are placed on the inclined portions 342 and 346 of the cam wall 34 (or on the other inclined portions 344 and 348 of the cam wall 34), the first cam follower wall 54 of the first linear moving body 50 divides again the first space 11 into a discharge space 111 and an inflow space 112 and isolates the two spaces 111 and 112 from each other. In addition, the second cam follower wall 56 of the first linear moving body 50 divides again the second space 12 into a discharge space 121 and an inflow space 122 and isolates the two spaces 121 and 122 from each other. Moreover, a first cam follower wall 64 of the second linear moving body 60 divides again the third space 13 into a discharge space 131 and an inflow space 132 and isolates the two spaces 131 and 132 from each other. Furthermore, a second cam follower wall 66 of the second linear moving body 60 divides again the fourth space 14 into a discharge space 141 and an inflow space 142 and isolates the two spaces 141 and 142 from each other.

Referring to Figs. 1, 2, 6 and 7, the first contacting member 70 has the annular contacting wall 71 perpendicular to the rotation axis 100, and the first, second, third and fourth division walls 75, 76, 77 and 78 standing from the contacting wall 71. One surface of the contacting wall 71 forms the first wall surface 231 of the rotating chamber 23, which is slidably in close contact with the two first contacting portions 341 and 345 of the cam wall 34. An outer surface 711 of the contacting wall 71 is in close contact with the sidewall 26 of the housing 20 and an inner surface 712 is slidably in close contact with the outer surface 41 of the rotational shaft 40. The contacting wall 71 is provided with the first guide passage 72 and the second guide passage 74 that are disposed at an interval of 180° to communicate with the first guide groove 265 and the second guide groove 266. The first cam follower wall 54 of the first linear moving body 50 is slidably received in the first guide passage 72. The first cam follower wall 64 of the second linear moving body 60 is slidably received in the second guide passage 74. Referring to these figures together with Fig. 9, communicating groove IA 715, communicating groove IB 716, communicating groove 1C 717 and communicating groove ID 718 located sequentially in the circumferential direction are provided in the outer surface of the contacting wall 71. Communicating groove IA 715 and communicating groove ID 718 are adjacently placed on both sides of the first guide passage 72, and communicating groove IB 716 and communicating groove 1C 717 are adjacently placed on both sides of the second guide passage 74. Communicating groove IA 715 causes the rotating chamber 23 to communicate with space IA 211 of the first gas chamber 21. Communicating groove IB 716 causes the rotating chamber 23 to communicate with space IB 212 of the first gas chamber 21. Communicating groove 1C 717 causes the rotating chamber 23 to communicate with space 1C 213 of the first gas chamber 21. Communicating groove ID 718 causes the rotating chamber 23 to communicate with space ID 214 of the first gas chamber 21. The first, second, third and fourth division walls 75, 76, 77 and 78 are radially disposed while being at regular intervals in the circumferential direction. Ends 751, 761, 771 and 781 of the division walls are in close contact with the first end wall 22 of the housing 20, and outer surfaces 752, 762, 772 and 782 of the division walls are in close contact with the sidewall 26 of the housing 20. Inner surfaces 753, 763, 773 and 783 of the division walls are slidably in close contact with the outer surface 41 of the rotational shaft 40. Space IA 211, spacelB 212, space 1C 213 and space ID 214 are sequentially disposed in the first gas chamber 21 in the circumferential direction and isolated from one another by the four division walls 75, 76, 77 and 78. The space between the first division wall 75 and the second division wall 76 becomes IA space 211. The space between the second division wall 76 and the third division wall 77 becomes space IB 212. The space between the third division wall 77 and the fourth division wall 78 becomes space 1C 213. The space between the fourth division wall 78 and the first division wall 75 becomes space 2D 214.

Although not shown in the drawings, the first contacting member 70 is coupled with the housing by means of a proper fixing means (for example, key coupling) to prevent relative rotation of the first contacting member with respect to the housing 20.

Since the second contacting member 80 is symmetrical with the first contacting member 70 in their structures, a detailed description thereof will be omitted. Referring to Figs. 2, 6 and 9, the second cam follower wall 56 of the first linear moving body 50 is slidably received in the first guide passage 82. The second cam follower wall 66 of the second linear moving body 60 is slidably received in the second guide passage 84. Communicating groove 2A 815 causes the rotating chamber 23 to communicate with space 2A 251 of the second gas chamber 25. Communicating groove 2B 816 causes the rotating chamber 23 to communicate with space 2B 252 of the second gas chamber 25. Communicating groove 2C 817 causes the rotating chamber 23 to communicate with space 2C 253 of the second gas chamber 25. Communicating groove 2D 818 causes the rotating chamber 23 to communicate with space 2D 254 of the second gas chamber 25. Space 2A 251, space 2B 252, space 2C 253 and space 2D 254 are sequentially disposed in the second gas chamber 25 in the circumferential direction and isolated from one another by four division walls 85, 86, 87 and 88. The space between the first division wall 85 and the second division wall 86 becomes space 2A 251. The space between the second division wall 86 and the third division wall 87 becomes space 2B 252. The space between the third division wall 87 and the fourth division wall 88 becomes space 2C 253. The space between the fourth division wall 88 and the first division wall 85 becomes space 2D 254.

Now, the operation of the compressor of this embodiment will be described in detail with reference to Figs. 1, 2, 5 and 9. Fig. 9 is a view showing the deployed state of the cam wall 34, simultaneously showing the first and second contacting members 70 and 80, and the respective cam follower walls 54, 56, 64 and 66 of the first and second linear moving bodies 50 and 60. When the rotational shaft 40 is rotated by the driving device (not shown) in a direction designated by an arrow in Fig. 1, the cam wall 34 is rotated in the arrow direction together with the rotational shaft. This corresponds to a linear rightward movement of the cam wall 34 deployed in Fig. 9. Referring to Fig. 9, the first linear moving body 50 and the second linear moving body 60 are placed on the two inclined portions 342 and 346 of the cam wall 34, respectively. Once the cam wall 34 moves in the arrow direction, each of the inflow spaces 112, 122, 132 and 142 of the first, second, third and fourth spaces 11, 12, 13 and 14 are enlarged, and each of the discharge spaces 111, 121, 131 and 141 of the first, second, third and fourth spaces 11, 12, 13 and 14 becomes narrow. Accordingly, gas in space IA 211 of the first gas chamber 21 is introduced into the inflow space 112 of the first space 11 through communicating groove IA 715. At this time, gas is sucked into space IA 211 of the first gas chamber 21 through the first suction port 221. Further, gas in the discharge space 111 of the first space 11 is discharged into space ID 214 of the first gas chamber 21 through communicating groove ID 718. Gas in space ID 214 is introduced into space 2A 251 of the second gas chamber 25 through the first communicating passage 200. Gas in space 2A 251 of the second gas chamber 25 is introduced into the inflow space 122 of the second space 12 through communicating groove 2A 815. In addition, gas in the discharge space 121 of the second space 12 is discharged into space 2D 254 of the second gas chamber 25 through communicating groove 2D 818. Gas in space 2D 254 is discharged through the first discharge port 241. Gas in space 1C 213 of the first gas chamber 21 is introduced into the inflow space 132 of the third space 13 through communicating groove 1C 717. At this time, gas is sucked into space 1C 213 of the first gas chamber 21 through the second suction port 222. Moreover, gas in the discharge space 213 of the third space 13 is discharged into space IB 212 of the first gas chamber 21 through communicating groove IB 716. Gas in space IB 212 is introduced into space 2C 253 of the second gas chamber 25 through the second communicating passage 205. Gas in space 2C 253 of the second gas chamber 25 is introduced into the inflow space 142 of the fourth space 14 through communicating groove 2C 817. Furthermore, gas in the discharge space 141 of the fourth space 14 is discharged into space 2B 252 of the second gas chamber 25 through communicating groove 2B 816. Gas in space 2B 252 is discharged through the second discharge port 242. In the above process, gas in the first and third spaces 11 and 13 is discharged through the second and fourth spaces 12 and 14 which are smaller than the first and third spaces 11 and 13, resulting in two-stage compression. In the above, it has been described that all the cam follower walls 54, 56, 64 and 66 of the two linear moving bodies 50 and 60 are operatively in close contact with the outer surface 41 of the rotational shaft 40 in a state where discharge pressure is lower than a set pressure. If the discharge pressure becomes higher than a primary set pressure, this discharge pressure is transmitted to the radially inner space 913 of the receiving space 911 of the first pressure adjusting unit 90 through the first discharge pressure communicating structure 94 and then pushes the piston 921 radially outwardly while overcoming an elastic force of the elastic member 93. Accordingly, the two cam follower walls 54 and 56 of the first linear moving body 50 are separated from the outer surface 41 of the rotational shaft 40 and are in a state shown in Fig. 10. In the state shown in Fig. 10, a discharge rate is reduced to 50% so that an increment of the discharge pressure is inhibited. If the discharge pressure is lowered below the primary set pressure, the compressor 10 returns to the state shown in Fig. 4. If the discharge pressure is continuously increased and becomes higher than a secondary set pressure which is higher than the primary set pressure, the discharge pressure is transmitted to the radially inner space 963 of the receiving space 961 of the second pressure adjusting unit 90 through the second discharge pressure communicating structure 99 and then pushes a piston 971 radially outwardly while overcoming an elastic force of the elastic member 98. Accordingly, the two cam follower walls 64 and 66 of the second linear moving body 60 are separated from the outer surface 41 of the rotational shaft 40 and are in a state shown in Fig. 11. In the state shown in Fig. 11, the discharge rate becomes zero (0) % so that an additional increment of the discharge pressure is inhibited. If the discharge pressure is lowered below the secondary set pressure, the compressor returns to the state shown in Fig. 10. Although not shown in the figures, it is desirable to provide a check valve at an appropriate location of the suction side. Figs. 12 to 14 are views showing a compressor according to a second embodiment of the present invention. Referring to Figs. 12 to 14, the compressor 10a has pairs of first and second cam follower walls 51a and 61a. The pair of first cam follower walls 51a comprises two separate cam follower walls 54a and 56a. The pair of second cam follower walls 61a comprises two separate cam follower walls 64a and 66a. Since each of the cam follower walls 54a, 56a, 64a and 66a is the same as that of each of the cam follower walls 54, 56, 64 and 66 shown in Fig. 2 in their structures, a detailed description thereof will be omitted. The compressor 10a is provided with pressing elastic members 150a for pushing the cam follower walls 54a, 56a, 64a and 66a toward a cam wall 34a. The pressing elastic members 150a are received in guide passages 72a, 74a, 82a and 84a of first and second contacting members 70a and 80a, respectively. The cam wall 34a is formed such that first contacting portions 341a and 345a are thicker than second contacting portions 343a and 347a, but the width of each of the first contacting portions is the same as that of each of the second contacting portions. Due to the shape of the cam wall 34a, first and third spaces 11a and 13a are larger than second and fourth spaces 12a and 14a. Accordingly, two-stage compression is performed in the same manner as the first embodiment. Contrary to the compressor 10 of the first embodiment, the compressor 10a of the second embodiment dose not have the pressure adjusting units 90 and 95. Since other structures and operations of the compressor of this embodiment are identical with those of the compressor of the first embodiment, detailed descriptions thereof will be omitted.

Figs. 15 to 20 are views showing a third embodiment of the present invention. Referring to Figs. 15 to 20, a fluid pump 10b comprises a cylindrical housing 20b, a rotating body 30b, a rotational shaft 40b extending along a rotation axis 100b, an intermediate contacting member 50b, linear moving bodies IA, IB, 2A and 2B 60b, 62b, 64b and 66b, and a discharge rate-adjusting unit consisting of a first control unit 70b and a second control unit 80b. The housing 20b has circular first and second end walls 22b and 24b which face each other and are perpendicular to the rotation axis 100b, and a sidewall 26b for connecting the both end walls 22b and 24b to each other. A cylindrical receiving space 21b for receiving the rotating body 30b, the intermediate contacting member 50b and linear moving bodies IA, IB, 2A and 2B 60b, 62b, 64b and 66b are formed in the housing 20b.

The receiving space 21b is provided with a first fluid chamber 23b and a second fluid chamber 25b in which a first cam wall 32b and a second cam wall 34b of the rotating body 30b to be described later are received, respectively. The first fluid chamber 23b is formed by first and second wall surfaces 231b and 232b that face each other, and third and fourth wall surfaces 233b and 234b for connecting the first and second wall surfaces 231b and 232b to each other. The first wall surface 231b is an inner surface of the first end wall 22b of the housing 20b, the second wall surface 232b is a wall surface of a first end of the intermediate contacting member 50b, the third wall surface 233b is formed by a portion of an outer surface of a rotor 38b of the rotational shaft 30b to be described below, and the fourth wall surface 234b is formed by a portion of an inner surface of the sidewall 26b of the housing 20b. Two first contacting portions 321b and 325b of the first cam wall 32b to be described later are in close surface-contact with the first wall surface 231b, and two second contacting portions 323b and 327b of the first cam wall 32b to be described later are in close surface-contact with the second wall surface 222b. A radial end of the first cam wall 32b with respect to the rotation axis 100b is in close contact with the fourth wall surface 234b. The fourth wall surface 234b of the first fluid chamber 23b is formed with suction communicating grooves IA and IB 211b and 213b and discharge communicating grooves IA and IB 212b and 214b which linearly extend to the first wall surface 231b and the second wall surface 232b in the extension direction of the rotation axis 100b. Suction communicating groove IA 211b - discharge communicating groove IA 212b - suction communicating groove IB 213b - discharge communicating groove IB 214b are disposed in order along the circumferential direction of the rotation axis 100b. Suction communicating groove IA 211b is adjacent to discharge communicating groove IB 214b, and discharge communicating groove IA 212b is adjacent to suction communicating groove IB 213b. Suction communicating groove IA 211b and suction communicating groove IB 213b communicate with communicating passage IA 52b and communicating passage IB 54b, which will be described later, formed in the intermediate contacting member 50b, respectively. Discharge communicating groove IA 212b and Discharge communicating groove IB 214b communicate with communicating passage 2A 53b and communicating passage 2B 55b, which will be described later, formed in the intermediate contacting member 50b, respectively. Linear moving body IA 60b to be described later is located between suction communicating groove IA 211b and discharge communicating groove IB 214b, and linear moving body IB 62b is located between discharge communicating groove IA 212b and suction communicating groove IB 213b.

The second fluid chamber 25b is formed by first and second wall surfaces 251b and 252b that face each other and third and fourth wall surfaces 253b and 254b for connecting the first and second wall surfaces 251b and 252b to each other. The first wall surface 251b is a wall surface of a second end of the intermediate contacting member 50b, the second wall surface 252b is an inner surface of the second end wall 24b, the third wall surface 253b is formed by a portion of an outer surface of the rotor 38b of the rotational shaft 30b to be described below, and the fourth wall surface 254b is formed by a portion of an inner surface of the sidewall 26b of the housing 20b, Two first contacting portions 341b and 345b of the second cam wall 34b to be described later are in close surface-contact with the first wall surface 251b, and two second contacting portions 343b and 347b of the second cam wall 34b to be described later are in close surface-contact with the second wall surface 252b. A radial end of the second cam wall 34b with respect to the rotation axis 100b is in close contact with the fourth wall surface 254b. The fourth wall surface 254b of the second fluid chamber 25b is formed with suction communicating grooves 2A and 2B 201b and 203b and discharge communicating grooves 2A and 2B 202b and 204b which linearly extend to the first wall surface 251b and the second wall surface 252b along the extension direction of the rotation axis 100b. Suction communicating groove 2A 201b - discharge communicating groove 2A 202b - suction communicating groove 2B 203b - discharge communicating groove 2B 204b are disposed in order along the circumferential direction of the rotation axis 100b. Suction communicating groove 2A 201b is adjacent to suction communicating groove 2B 204b, and discharge communicating groove 2 A 202b is adjacent to suction communicating groove 2B 203b. Suction communicating groove 2A 201b and suction communicating groove 2B 203b communicate with communicating passage IA 52b and communicating passage IB 54b, which will be described later, formed in the intermediate contacting member 50b, respectively. Discharge communicating groove 2A 202b and discharge communicating groove 2B 204b communicate with communicating passage 2A 53b and communicating passage 2B 55b, which will be described later, in the intermediate contacting member 50b, respectively. Linear moving body 2A 64b to be described later is located between suction communicating groove 2A 201b and discharge communicating groove 2B 204b, and linear moving body 66b 2B is located between discharge communicating groove 2A 202b and suction communicating groove 2B 203b. The rotational shaft 40b passes through the centers of the two end walls 22b and 24b of the housing 20b and is rotatably supported by first and second bearings 42b and 44b provided at the centers of the two end walls 22b and 24b. The rotational shaft 40b extends out of the end wall 22b along the rotation axis 100b and is coupled to and rotated by a driving device (not shown). The two end walls 22b and 24b of the housing 20b are formed with slits 221b and 241b in which linear moving bodies IA, IB, 2A and 2B 60b, 62b, 64b and 66b are partially received. A groove 261b is provided in an inner wall surface of the sidewall 26b of the housing 20b, and a radially outer end of each of linear moving bodies IA, IB, 2A and 2B 60b, 62b, 64b and 66b is received in the groove 261b.

The rotating body 30b has the cylindrical rotor 38b extending along the rotation axis 100b, and the first and second cam walls 32b and 34b protruding from the rotor 38b radially outwardly with respect to the rotation axis 100b. The rotor 38b is coupled to and rotated with the rotational shaft 40 about the rotation axis 100b. An annular groove 39b formed in a circumferential direction is provided in a sidewall surface of the rotor 38b. The annular groove 39b is located between the first cam wall 32b and the second cam wall 34b. A flange 59b of the intermediate contacting member 50b to be described later is fitted into the annular groove 39b. Both surfaces 31b and 33b of the first cam wall 32b surround an outer periphery of the rotor 38b so as to face the first wall surface 231b and the second wall surface 232b of the first fluid chamber 23b, respectively. One of the both surfaces 31b and 33b of the first cam wall 32b, which faces the first wall surface 231b of the first fluid chamber 23b, is referred to as "the first surface 31b" and the other surface thereof facing the second wall surface 232b of the first fluid chamber 23b is referred to as "the second surface 33b". Referring to Fig. 6 showing the deployed state of the rotating body 30b, the first cam wall 32b comprises flat contacting portions IA and IB 321b and 325b which are perpendicular to the rotation axis 100b to be in surface-contact with the first wall surface 231b of the first fluid chamber 23b, flat contacting portions2A and 2B 323b and 327b which are perpendicular to the rotation axis 100b to be in surface-contact with the second wall surface 232b of the first fluid chamber 23b, and four inclined portions 322b, 324b, 326b and 328b that are inclined with respect to the rotation axis 100b and connect the adjacent contacting portions. Contacting portion IA 321b and contacting portion IB 325b are placed at an interval of about 180° around the rotation axis 100b. Contacting portion 2A 323b and contacting portion 2B 327b are placed at an interval of about 180° around the rotation axis 100b. Each of the contacting portions 321b, 323b, 325b and 327b is formed such that the width of an end thereof is larger than that of a section where the suction communicating groove 211b or 213b or the discharge communicating groove 212b or 214b is provided. Each of four inclined portions 322b, 324b, 326b and 328b is inclined with respect to the rotation axis 100b and smoothly connects two adjacent contacting portions. That is, the first cam wall 32b is formed by connecting contacting portion IA 321b - the inclined portion 322b - contacting portion 2A 323b - the inclined portion 324b - contacting portion IB 325B - the inclined portion 326B - contacting portion 2B 327b - the inclined portion 328B in the circumference direction around an outer periphery of the rotor 38b. A radial end of the first cam wall 32b with respect to the rotation axis 100b is in close contact with the fourth wall surface 234b of the first fluid chamber 23b. Due to the structure of the first cam wall 32b, the first fluid chamber 23b is divided into spaces IA and 1C lib and 13b provided by the first wall surface 231b and the first surface 31b of the first cam wall 32b and spaces IB and ID 12b and 14b provided by the second wall surface 232b of the first fluid chamber 23b and the second surface 33b of the first cam wall 32b. The first cam wall 32b is provided with four vanes 36b that are movable and subjected to a centrifugal force radially outwardly in response to the rotation of the rotating body 30b. Each of the vanes 36b is slantly disposed along the inclined portion 322b, 324b, 326b or 328b so as to connect two adjacent contacting portions to each other. A radial end of each of the vanes 36b is slidably in close contact with the fourth wall surface 234b of the first fluid chamber 23b. Each space of the first fluid chamber 23b is more effectively sealed by each vane 36b. The first cam wall 32b interacts with linear moving bodies IA and IB 60b and 62b. Since the structure of the second cam wall 34 is the same as that of the first cam wall 32b, a detailed description thereof will be omitted. However, there is a phase difference of 90° about the rotation axis 100b between the second cam wall 34b and the first cam wall 32b. Due to the second cam wall 34b, the second fluid chamber 25b is divided into spaces 2A and 2C 15b and 17b provided by the first wall surface 251b and a first surface 35b of the second cam wall 324 and spaces 2B and 2D 16b and 18b provided by the second wall surface 252b of the second fluid chamber 25b and a second surface 37b of the second cam wall 34b. The second cam wall 34b interacts with linear moving bodies 2A and 2B 64b and 66b. Due to the phase difference between the two cam walls 32b and 34b, linear moving bodies IA and IB 60b and 62b and linear moving bodies 2A and 2B 64b and 66b simultaneously move toward each other or far away from each other. Accordingly, eccentricity is reduced in the pump.

Linear moving body IA 60b is provided with a first cam follower wall 601b, a second cam follower wall 602b and a connecting portion 603b. Opposing corners 6011b and 6021b of the first and second cam follower walls 601b and 602b are slidably in close contact with the first surface 31b and the second surface 33b of the first cam wall 32b, respectively. Corners 6012b and 6022b connected to the opposing corners 6011b and 6021b of the first and second cam follower walls 601b and 602b are slidably in close contact with the third wall surface 233b of the fist fluid chamber 23b. The connecting portion 603b connects the first cam follower wall 601b to the second cam follower wall 602b at a radial end side, and is slidably in close contact with a radial end of the first cam wall 32b. The first cam follower wall 601b and the second cam follower wall 602b form a pair of cam follower walls. Linear moving body IA 60b interacts with the first cam wall 32b and can linearly move along the rotation axis 100b. Linear moving body IB 62b is the same as that of linear moving body IA 60b in their structures and is disposed to be symmetrical with linear moving body IA 60b about the rotation axis 100b. Linear moving body 2A 64b and linear moving body 2B 66B are the same as that of linear moving body IA 60b in their structures and are symmetrical with each other about the rotation axis 100b so as to interact with the second cam wall 34b.

The intermediate contacting member 50b surrounds the rotor 38b between the first cam wall 32b and the second cam wall 34b of the rotating body 30b, and both ends of the intermediate contacting member form the second wall surface 232b of the first fluid chamber 23b and the first wall surface 251b of the second fluid chamber 25b, respectively. The intermediate contacting member 50b is divided into two parts by a separating surface 51b that passes both ends of the intermediate contacting member. The intermediate contacting member 50b is formed with four slits 56b in which linear moving bodies IA, IB, 2A and 2B 60b, 62b, 64b and 66b are partially received. The protruding flange 59b is provided on an inner peripheral surface of the intermediate contacting member 50b, so that the flange can be fitted into the annular groove 39b formed in the rotor 38b of the rotating body 30b. The flange 59b can establish more effective sealing between the first fluid chamber 23b and the second fluid chamber 25b. In an outer peripheral surface of the intermediate contacting member 50b, communicating passages IA, 2A, IB and 2B are provided in the form of grooves. Communicating passage IA 52b causes suction communicating groove IA 211b to communicate with suction communicating groove 2A 201b. Communicating passage IB 54b causes suction communicating groove IB 213b to communicate with suction communicating groove 2B 203b. Both ends of communicating passage IA 52b and both ends of communicating passage IB 54b become the suction ports of the first and second fluid chambers 23b and 25b, respectively. Communicating passage IA 52b and communicating passage IB 54b are connected to a suction tube 90b. Communicating passage 2A 53b causes discharge communicating groove IA 212b to communicate with discharge communicating groove 2A 202b. Communicating passage 2B 55b causes discharge communicating groove IB 214b to communicate with discharge communicating groove 2B 204b. Both ends of communicating passage 2A 53b and both ends of communicating passage 2B 55b become the discharge ports of the first and second fluid chambers 23b and 25b. Communicating passage 2A 53b communicates with an inflow port 73b of the first control unit 70b, which will be described later, and communicating passage 2B 55b communicates with an inflow port 83b of the second control unit 80b, which will be described later. The intermediate contacting member 50b is fixed to the housing 20b.

The discharge rate-adjusting unit comprises the first control unit 70b and the second control unit 80b formed outside the sidewall 26b of the housing 20b. The first control unit 70b comprises a first room 72b located radially outside the rotation axis 100b, a second room 72b located radially inside the rotation axis, a moving member 76b capable of moving within the first room 72b in a radial direction, and an elastic member 78b for pushing the moving member inwardly in the radial direction. In a sidewall 71b of the first room 72b, a discharge port 75b, the inflow port 73b and a communicating port 77b are formed in order from a radially outward side to a radially inward side with respect to the rotation axis 100b. The discharge port 75b communicates with a discharge tube 92b. The inflow port 73b communicates with communicating passage 2B 55b. The communicating port 77b communicates with communicating passage IA 52b. The second room 74b communicates with the discharge tube 92b. The moving member 76b has a supporting plate 761b, a coupling rod 762b, a separating plate 763b and an extension rod 764b, which are provided in order from the radially outward side to the radially inward side with respect to the rotation axis 100b. The supporting plate 761b is in contact with the elastic member 78 and receives an elastic force from the elastic member 78. The coupling rod 762b connects the supporting plate 761b and the separating plate 763b. The separating plate 763b divides the first room 72b into two spaces in the radial direction with respect to the rotation axis 100b. An end of the extension rod 764 is coupled to the second room 74b so that the pressure of the second room 74b is applied to the extension rod. The moving member 76b moves in the radial direction with respect to the rotation axis 100b, and causes the inflow port 73b to communicate with the discharge port 75b or with the communicating port 77b according to the position of the separating plate 763b. If the discharge pressure becomes lower than a first reference pressure, the inflow port 73b communicates with the discharge port 75b as shown in Fig. 19. If the discharge pressure becomes higher than a second reference pressure, the moving member 76b then moves radially outwardly while overcoming the pushing force of the elastic member 78b, thereby causing the inflow port 73b to communicate with the communicating port 77b. The structure of the second control unit 80b is the same as that of the first control unit 70b. However, there is a difference between the two control units in that the elastic force of an elastic member 88b of the second control unit 80b is less than that of the elastic member 78b of the first control unit 70b. The inflow port 83b of the second control unit 80b communicates with communicating passage 2B 55b. A communicating port 87b communicates with communicating passage IB 54b. If the discharge pressure becomes lower than the first reference pressure which is less than the second reference pressure, the inflow port 83b and a discharge port 85b communicate with each other by the pushing force of the elastic member 88. If the discharge pressure becomes higher than the first reference pressure, a moving member 86b then moves radially outwardly while overcoming the pushing force of the elastic member 88b, thereby causing the inflow port 83b to communicate with the communicating port 87b as shown in Fig. 5. Now, the operation of this embodiment will be described in detail with reference to Figs. 19 and 20. First, a state where a fluid is sucked into and discharged from the fluid chambers 23b and 25b will be explained with reference to Fig. 6. The first cam follower wall 601b of linear moving body IA 60b divides space IA lib of the first fluid chamber 23b into space IA-I 111b and space 1A-2 112b in the arrow direction, and the second cam follower wall 602b divides space IB 12b of the first fluid chamber 23b into space IB-1 121b and space 1B-2 122b in the arrow direction. A first cam follower wall 621b of linear moving body IB 62b divides space 1C 13b of the first fluid chamber 23b into space IC-I 131b and space lC-2 132b in the arrow direction, and a second cam follower wall 622b divides space ID 14b of the first fluid chamber 23b into space ID-I 141b and space 1D-2 142b in the arrow direction. Space IA-I 111b and space IB-I 121b communicate with each other through discharge communicating groove IB 214b. Space 1A-2 112b and space 1B-2 122b communicate with each other through suction communicating groove IA 211b. Space IC-I 131b and space ID-I 141b communicate with each other through discharge communicating groove IA 212b. Space lC-2 132b and space 1D-2 142b communicate with each other through suction communicating groove IB 213b. A first cam follower wall 641b of linear moving body 2A 64b divides space 2A 15b of the second fluid chamber 25b into space 2A-1 151b and space 2A-2 152b in the arrow direction, and a second cam follower wall 642b divides space 2D 18b of the second fluid chamber 25b into space 2D-1 181b and space 2D-2 182b in the arrow direction. A first cam follower wall 661b of linear moving body 2B 66b divides space 2C 17b of the second fluid chamber 25b into space 2C-1 171b and space 2C-2 172b in the arrow direction, and a second cam follower wall 662b divides space 2B 16b of the second fluid chamber 25b into space 2B-1 161b and space 2B-2 162b in the arrow direction. Space 2A-1 151b and space 2D-1 181b communicate with each other through discharge communicating groove 2B 204b. Space 2A-2 152b and space 2D-2 182b communicate with each other through suction communicating groove 2A 201b. Space 2C-1 171b and space 2B-1 161b communicate with each other through discharge communicating groove 2A 202b. Space 2C-2 172b and space 2B-2 162b communicate with each other through suction communicating groove 2B 203b. If the rotational shaft 40b shown in Fig. 15 rotates in the arrow direction, the state shown in Fig. 20 becomes a state where the first cam wall 32b and the second cam wall 34b move in the arrow direction. Due to the movements of the first cam wall 32b and the second cam wall 34b in the arrow direction, volumes of space 1A-2 112b, space 1B-2 122b, space lC-2 132b and space 1D-2 142b of the first fluid chamber 23b and space 2A-2 152b, space 2D-2 182b, space 2C-2 172b and space 2B-2 162b of the second fluid chamber 25b are increased to suck the fluid thereinto. Further, volumes of space IA-I 111b, space IB-I 121b, spacelC-1 131b and spacelD-1 141b of the first fluid chamber 23b and space 2A-1 151b, space 2D-1 181b, space 2C-1 171b and space 2B-1 161b of the second fluid chamber 25b are reduced to discharge the fluid therefrom. That is, as the rotating body 30b is rotated, the fluid sucked through communicating passage IA 52b is discharged through communicating passage 2A 53b, and the fluid sucked through communicating passage IB 54b is discharged through communicating passage 2B 55b. This process of discharging the fluid is repeated. At this time, in a case where the discharge pressure is higher than the first reference pressure and is lower than the second reference pressure, the states of the first control unit 70b and the second control unit 80b of the discharge rate-adjusting unit become the state shown in Fig. 5. That is, the control unit 70b causes the inflow port 73b to communicate with the discharge port 75b and the second control unit 80b causes the inflow port 83b to communicate with the communicating port 87b. Thus, the fluid sucked through communicating passage IA 52b passes through the second control unit 80b and then is discharged through communicating passage 2B 55b. In this state, once the discharge pressure becomes higher than the second reference pressure, the first control unit 70b causes the inflow port 73b to communicate with the communicating port 77b, thereby making the discharge rate to zero (0). In the state shown in Fig. 19, once the discharge pressure becomes lower than the first reference pressure, the second control unit 80b causes the inflow port 83b to communicate with the discharge port 85b, thereby increasing the discharge rate by two times.

Fig. 21 shows another embodiment of the cam wall shown in Fig. 16. A vane 36c extends in a circumferential direction and comprises two separate semi-circular members.

Fig. 22 is a deployed view showing the interior of a fluid pump according to a fourth embodiment of the present invention. Referring to Fig. 22, by forming communicating passages 52c and 54c for causing discharge ports 53c and 55c of a first fluid chamber 23c to communicate with inflow ports 57c and 59c of a second fluid chamber 25c, a fluid sucked into the first fluid chamber 23c passes through the second fluid chamber 25c and then is discharged, resulting in dual compression. To enable the dual compression, a second cam wall 34c is formed to be thicker than a first cam wall 32c.

Fig. 23 is a view showing another embodiment of the fluid pump shown in Fig. 15, in which a discharge rate-adjusting unit is independently installed. Referring to Fig. 23, two control units 7Od and 80d share a second room 74d to obtain a single integrated discharge rate-adjusting unit. Since other structures and functions of this embodiment are the same as those of the first embodiment except the single integrated discharge rate- adjusting unit, detailed descriptions thereof will be omitted. Figs. 24 (a) to (c) are views showing another embodiment of the discharge rate- adjusting unit of the fluid pump shown in Fig. 15 in accordance with operating states thereof. The discharge rate-adjusting unit 7Oe comprises a first room 72e, a second room 74e, a moving member 76e that can move in the first room 72e, and an elastic member 78e for pushing the moving member 76 toward the second room 74e. A sidewall 721e of the first room 72e is formed with a discharge port 75e, a first inflow port 73 Ie, a second inflow port 732e and a communicating port 77e in this order toward the second room 74e. The discharge port 75e communicates with a discharge tube 92e. The first inflow port 73 Ie communicates with communicating passage 2A 53b in Fig. 20. The second inflow port 732e communicates with communicating passage 2B 55b in Fig. 20. The communicating port 77e communicates with the suction tube 90b shown in Fig. 15. The second room 74e communicates with the discharge tube 92e. The moving member 76e is the same as the moving member of the third embodiment in terms of their structures. A separating plate 763 e divides the first room 72e into two spaces. Depending on the discharge pressure, the position of the separating plate 763e is changed. The fluid pump operates in three different ways as shown in Figs. 24 (a) to (c) according to the position of the separating plate 763e. Referring to Fig. 24 (a), since the discharge pressure is lower than the first reference pressure, the separating plate 763e is fully pushed toward the second room 74e by the elastic member 78e so that the both inflow ports 73 Ie and 732e communicate with the discharge port 75, resulting in a fluid discharge of 100%. If the discharge pressure becomes higher than the first reference pressure in the state of Fig. 24 (a), the separating plate 763e moves, leading to the state shown in Fig. 24 (b). Referring to Fig. 24 (b), the separating plate 763e is placed between the first inflow port 73 Ie and the second inflow port 732e, so that the first inflow port 73 Ie communicates with the discharge port 75e and the second inflow port 732e communicates with the communicating port 77e, resulting in a fluid discharge of 50%. If the discharge pressure is more increased and becomes higher than the second reference pressure in the state of Fig. 24 (b), the separating plate 763e further moves, leading to the state shown in Fig. 24 (c). Referring to Fig. 24 (c), the separating plate 763e is placed between the first inflow port 73 Ie and the discharge port 75e, so that the both inflow ports 731e and 732e communicate with the communicating port 77e, resulting in a discharge rate of zero (0).

Although the present invention has been described in connection with the embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes and modifications can be made thereto without departing from the sprit and scope of the present invention, and such changes and modifications also fall within the scope of the present invention.

Claims

1. A fluid pump for a compressor, comprising: a rotating chamber formed by first and second opposing wall surfaces and a third cylindrical wall surface for connecting the first and second wall surfaces to each other; a rotating body including a rotational shaft rotating about a rotation axis passing centers of the first and second wall surfaces, and a cam wall protruding radially outwardly from an outer surface of the rotational shaft so that an end of the cam wall can be slidably in close contact with the third wall surface of the rotating chamber, the cam wall including a first contacting portion slidably brought into close contact with the first wall surface of the rotating chamber, a second contacting portion slidably brought into close contact with the second wall surface, and an inclined portion for connecting the first and second contacting portions to each other; and a pair of cam follower walls interacting with the cam wall and moving linearly according to rotation of the rotating body, the cam follower walls being disposed such that a corner of one of the cam follower walls faces a corner of the other one of the cam follower walls, the opposing corners of the cam follower walls being slidably in contact with both surfaces of the cam wall, and other corners adjacent to the opposing corners being slidably in contact with the outer surfaces of the rotational shaft of the rotating body, wherein the first wall surface is formed with an inflow passage and a discharge passage that communicate with a space where the cam wall is placed in the rotating chamber and are provided respectively at both sides of the cam follower wall, the second wall surface is formed with an inflow passage and a discharge passage that communicate with the space where the cam wall is placed in the rotating chamber and are provided respectively at both sides of the cam follower wall, a communicating passage is provided to cause the discharge passage of the first wall surface to communicate with the inflow passage of the second wall surface, and the space where the cam wall is placed in the rotating chamber is divided into a first space capable of communicating with the passages formed in the first wall surface and a second space capable of communicating with the passages formed in the second wall surface by the cam wall, the first space being larger than the second space.

2. The fluid pump as claimed in claim 1, further comprising: a first gas chamber placed on the side of the first wall surface of the rotating chamber; a second gas chamber placed on the side of the second wall surface of the rotating chamber; a first contacting member separating the rotating chamber and the first gas chamber, the first contacting member being formed with the first wall surface to come into contact with the first contacting portion of the cam wall and having a first contacting wall provided with the inflow passage and the discharge passage; and a second contacting member separating the rotating chamber and the second gas chamber, the second contacting member being formed with the second wall surface to come into contact with the second contacting portion of the cam wall and having a second contacting wall provided with the inflow passage and the discharge passage , wherein the first contacting member has a division wall extending from the first contacting wall to divide the first gas chamber into spaces communicating with the inflow passage and the discharge passage of the first contacting wall in one-to-one correspondence, the second contacting member has a division wall extending from the second contacting wall to divide the second gas chamber into spaces communicating with the inflow passage and the discharge passage of the second contacting wall in one-to-one correspondence, and the space of the first gas chamber communicating with the inflow passage of the first contacting wall communicates with a suction port through which gas is sucked, and the space of the second gas chamber communicating with the discharge passage of the second contacting wall communicates with a discharge port through which gas is discharged.

3. The fluid pump as claimed in claim 1 or 2, wherein the first contacting portion of the cam wall has a radial width smaller than that of the second contacting portion.

4. The fluid pump as claimed in claim 3, wherein the cam wall has a constant thickness in a direction of the rotation axis, and the pair of cam follower walls is integrated with each other to form a cam follower wall body.

5. The fluid pump as claimed in claim 4, wherein the cam follower wall body has a contacting portion to come into contact with a radial end of the cam wall, and the contacting portion is provided with a groove recessed radially outwardly.

6. The fluid pump as claimed in claim 4, further comprising a guide groove enabling a radial movement of the cam follower wall body, and a pressure adjusting unit for adjusting a radial position of the cam follower wall body.

7. The fluid pump as claimed in claim 6, wherein the pressure adjusting unit comprises: a cylinder; a moving member coupled to the cam follower wall body and provided with a piston that is received in the cylinder and can move in a radial direction; an elastic member for pushing the piston radially inwardly; and a discharge pressure communicating passages for supplying pressure of discharged gas into the cylinder so as to provide pressure used for pushing the piston radially outwardly.

8. The fluid pump as claimed in claim 7, wherein the cam wall is provided with two first contacting portions, two second contacting portions, two cam follower wall bodies, two guide grooves and two pressure adjusting units.

9. The fluid pump as claimed in claim 8, wherein one of the elastic members of the two pressure adjusting units provides an elastic force larger than that of the other of the elastic members of the pressure adjusting units.

10. The fluid pump as claimed in claim 1 or 2, wherein the first contacting portion of the cam wall has a thickness in a direction of the rotation axis that is larger than that of the second contacting portion.

11. The fluid pump as claimed in claim 10, wherein the cam wall has two first contacting portions, two second contacting portions and two pairs of cam follower walls.

12. The fluid pump as claimed in claim 11, further comprising an elastic member for pushing the cam follower wall toward the cam wall.

13. A fluid pump, comprising: a first rotating body including a first rotor extending along a rotation axis and a first cam wall protruding from the first rotor radially outwardly with respect to the rotation axis, the first cam wall extending in a circumferential direction about the rotation axis so as to surround the first rotor; a second rotating body including a second rotor extending along the rotation axis and a second cam wall protruding from the second rotor radially outwardly with respect to the rotation axis, the second cam wall extending in the circumferential direction about the rotation axis so as to surround the second rotor; a first fluid chamber in which the first cam wall of the first rotating body is received, the first fluid chamber being divided into a plurality of spaces by the first cam wall; a second fluid chamber in which the second cam wall of the second rotating body is received, the second fluid chamber being divided into a plurality of spaces by the second cam wall; a pair of first cam follower walls interacting with both surfaces of the first cam wall; and a pair of second cam follower walls interacting with the second cam wall, wherein each of the fluid chambers is formed by a first wall surface and a second surface perpendicular to the rotation axis, a third wall surface that is an outer peripheral surface of each of the rotors, and a fourth wall surface slidably in contact with a radial end of each of the cam walls, each of the cam walls is provided with a first contacting portion slidably in contact with the first wall surface of the fluid chamber in which the cam wall is received, a second contacting portion slidably in contact with the second wall surface of the fluid chamber in which the cam wall is received, and an inclined portion connecting the first contacting portion and the second contacting portion and inclined with respect to a circumferential extension line of the rotation axis, one corner of one cam follower wall of each pair of cam follower walls faces one corner of the other cam follower wall of the pair of cam follower walls, the opposing corners of the cam follower walls being slidably in contact with both surfaces of the cam wall interacting with the corners, the other corners are slidably in contact with the third wall surface of the fluid chamber, and the pair of cam follower walls linearly moves according to rotation of the cam wall interacting therewith, the two cam walls are formed such that the pair of first cam follower walls and the pair of second cam follower walls simultaneously move toward each other or far away from each other, and each of the first and second fluid chambers has a suction port and a discharge port provided on both sides of the pair of cam follower walls.

14. The fluid pump as claimed in claim 13, wherein each of the fluid chambers has a suction communicating groove and a discharge communicating groove formed on both sides of the pair of cam follower walls, the suction communicating groove and the discharge communicating groove extend from the first wall surface to the second wall surface to cause both spaces with the received cam wall interposed therebetween to communicate with each other, the suction communicating groove communicates with a suction port through which a fluid is sucked, the discharge communicating groove communicates with a discharge port through which the fluid is discharged, and the first and second contacting portions of each of the cam walls are formed such that the suction communicating groove and the discharge communicating groove can simultaneously enter a distal section at a certain position as the cam wall is rotated.

15. The fluid pump as claimed in claim 14, further comprising a first communicating passage for causing the suction port of the first fluid chamber to communicate with the suction port of the second fluid chamber, and a second communicating passage for causing the discharge port of the first fluid chamber to communicate with the discharge port of the second fluid chamber.

16. The fluid pump as claimed in claim 15, further comprising a discharge rate- adjusting unit including a control unit, the control unit having a communicating port communicating with the first communicating passage, an inflow port communicating with the first communicating passage, and a discharge port, the control unit causing the inflow port to communicate with the discharge port or the communicating port to communicate with the inflow port according to pressure in the discharge port.

17. The fluid pump as claimed in claim 16, wherein the control unit comprises a first room provided with the communicating port, the inflow port and the discharge port; a second room communicating with the discharge port; a moving member provided moveably in the first room and subjected to pressure from the second room; and an elastic member for pushing the moving member in a direction resisting the pressure of the second room, and the moving member has a division wall for dividing the first room into a space communicating with the communicating port and a space communicating with the discharge port.

18. The fluid pump as claimed in claim 17, wherein the first cam wall has two first contacting portions, two second contacting portions, and two pairs of first cam follower walls, and the suction communicating groove and the discharge communication groove are provided on both sides of each of the pairs of first cam follower walls, the second cam wall has two first contacting portions, two second contacting portions, and two pairs of second cam follower walls, and the suction communicating groove and the discharge communication groove are provided on both sides of each of the pairs of second cam follower walls, two suction communicating grooves and two discharge communication grooves are provided, and the discharge rate-adjusting unit has two control units, and the discharge ports of the two control units communicate with each other.

19. The fluid pump as claimed in claim 18, wherein the second spaces of the two control units of the discharge rate-adjusting unit are formed into a single space.

20. The fluid pump as claimed in claim 14, wherein the first cam wall has two first contacting portions, two second contacting portions, and two pairs of first cam follower walls, and the suction communicating groove and the discharge communication groove are provided on both sides of each of the pairs of first cam follower walls, the second cam wall has two first contacting portions, two second contacting portions, and two pairs of second cam follower wall pairs, and the suction communicating groove and the discharge communication groove are provided on both sides of each of the pairs of second cam follower walls, two suction communicating grooves and two discharge communication grooves are provided, and the fluid pump further comprises a discharge rate-adjusting unit including a control unit, the control unit having a communicating port communicating with the first communicating passage or the second communicating passage, two inflow ports communicating with the two second communicating passages, and a discharge port, the control unit causing at least one of the two inflow ports to communicate with the discharge port or the communicating port to communicate with the two inflow ports according to pressure in the discharge port.

21. The fluid pump as claimed in claim 20, wherein the control unit comprises a first room provided with the communicating port, the two inflow ports and the discharge port; a second room communicating with the discharge port; a moving member provided moveably in the first room and subjected to pressure from the second room; and an elastic member for pushing the moving member in a direction resisting the pressure of the second room, and the moving member has a division wall for dividing the first room into a space communicating with the communicating port and a space communicating with the discharge port.

22. The fluid pump as claimed in claim 14, further comprising a communicating passage for causing the discharge port of the first fluid chamber to communicate with the suction port of the second fluid chamber.

23. The fluid pump as claimed in any one of claims 13 to 22, wherein the first rotor of the first rotating body and the second rotor of the second rotating body are formed integrally with each other.

24. The fluid pump as claimed in claim 23, further comprising an intermediate member surrounding the rotor between the first cam wall and the second cam wall, the intermediate member having both ends forming the first wall surface or the second wall surface of the first and second fluid chambers, the intermediate member being divided into two parts by a separating surface passing the both ends thereof.

25. The fluid pump as claimed in any one of claims 13 to 22, wherein a radial end of each of the cam walls is provided with a vane that is movable radially outwardly.

26. The fluid pump as claimed in claim 25, wherein the vane connects a first contacting portion of the cam wall to a second contacting portion adjacent to the first contacting portion.

27. The fluid pump as claimed in claim 25, wherein the vane extends along the circumferential direction about the rotation axis.

28. The fluid pump as claimed in claim 27, wherein two separate vanes are provided.