JP2007077946A - Multi-stage rotary expander - Google Patents

Abstract

In a conventional two-stage rotary expander, a differential pressure acting on a first vane is insufficient, and a tip side of the first vane is separated from a first piston.
In the multistage rotary expander, the average position of the swinging motion of the contact point between the tip end of the first vane 301 and the first piston 209 is closer to the suction side than the center in the width direction of the first vane 301. With this configuration, in the R-shaped surface 301a on the distal end side of the first vane 301, the area in which the pressure in the discharge-side working chamber 215b acts than the area in which the pressure in the suction-side working chamber 215a acts. And the differential pressure between the front end side and the back side of the first vane 301 can be increased, so that the front end of the first vane 301 is separated from the first piston 209 and the working fluid leaks. The present invention provides a multi-stage rotary expander that is highly effective and prevents high-efficiency.
[Selection] Figure 3

Description

  The present invention relates to a rotary expander that generates power by recovering expansion energy of a high-pressure compressive fluid, and more particularly to a multi-stage rotary expander including a plurality of cylinders.

  As an expander used for the purpose of recovering expansion energy when the refrigerant of the refrigeration cycle apparatus expands, a rotary type as shown in Patent Document 1 or a two-stage rotary type expander as shown in Patent Document 2 is used. Are known.

  The structure of the conventional rotary expander shown in Patent Document 1 will be described below. 9 is a longitudinal sectional view showing a configuration of a conventional rotary expander 100, and FIG. 10 is a transverse sectional view taken along line D1-D1 of the rotary expander of FIG.

  The generator 101 includes a stator 101a fixed to the hermetic container 102 and a rotor 101b fixed to the shaft 103. The rotor 101b rotates to generate an electromotive force between the stator 101a and the stator 101a to obtain electric power. . The shaft 103 passes through the cylinder 104 and is rotatably supported by bearings 105 and 106. The shaft 103 is provided with an eccentric portion 103a, and a piston 107 disposed inside the cylinder 104 is fitted into the eccentric portion 103a. In the shaft 103, there is an axial flow path 103 b along the long axis direction of the shaft 103, and on the upper side of the eccentric portion 103 a is a radial flow path 103 c that connects the axial flow path 103 b and the surface of the shaft 103. Is provided. Further, the bearing 105 is provided with a suction hole 105a that opens to an end surface on the cylinder 104 side, and a suction passage 105b that opens to a sliding surface with the shaft 103 and one opens to the suction hole 105a.

  As shown in FIG. 10, a vane groove 104 a is formed in the cylinder 104, and the vane 108 that is reciprocally held by the vane groove 104 a is in close contact with the piston 107 due to a differential pressure described later. . In addition, since a differential pressure does not act at the time of starting, the spring 109 is supplementarily provided on the back side of the vane 108. A crescent-shaped space formed by the cylinder 104 and the piston 107 is divided into two working chambers 110 a and 110 b by the vane 108. A suction hole 105a provided in the bearing 105 communicates with the working chamber 110a, and a discharge hole 104b provided in the cylinder 104 communicates with the working chamber 110b.

  The high-pressure working fluid flows into the sealed container 102 from the suction pipe 111 and then reaches the radial flow path 103 c via the axial flow path 103 b of the shaft 103. Although the radial flow path 103 c rotates with the shaft 103, the suction path 105 b is fixed to the bearing 105, so that the radial flow path 103 c and the suction path 105 b become connected and disconnected with the rotational movement of the shaft 103. repeat. The working fluid is sucked into the working chamber 110a while the radial flow path 103c and the suction path 105b are in communication. Thereafter, when the radial flow path 103c and the suction path 105b are disconnected, the suction stroke ends. The working fluid expands while reducing pressure, rotates the shaft 103 in a direction in which the volume of the working chamber 110a increases, and drives the generator 101. As the shaft 103 rotates, the working chamber 110a moves to the working chamber 110b that communicates with the discharge hole 104b, and the expansion stroke ends. Then, the working fluid having a low pressure is discharged from the discharge hole 104b to the discharge pipe 112 in the discharge stroke.

  FIG. 11 shows the relationship between the rotation angle of the shaft 103 and the pressure in the working chambers 110a and 110b when the rotary expander 100 of FIG. 9 is used in a refrigeration cycle using carbon dioxide as a working fluid. The rotation angle of the shaft 103 is based on the state in which the vane 108 is pushed most into the vane groove 104a. The rotary expander 100 sucks carbon dioxide in a supercritical state at a suction pressure Ps, and discharges carbon dioxide in a gas-liquid two-phase state at a discharge pressure Pd. The pressure in the working chamber 110a is constant at the suction pressure Ps during the suction stroke, and is reduced from the suction pressure Ps to the discharge pressure Pd during the expansion stroke. At that time, the pressure rapidly decreases in the first single-phase expansion, and then the pressure change becomes gentle in the expansion accompanied by the phase change. The pressure in the working chamber 110b is constant at the discharge pressure Pd because only the discharge stroke is performed.

  12 is an enlarged cross-sectional view of the vicinity of the working chamber taken along line D1-D1 of the rotary expander of FIG. A and B are edges composed of the R-shaped surface 108a and the side surface on the tip side of the vane 108, C and D are edges composed of the back surface and the side surface of the vane 108, and the R-shaped surface 108a and the piston 107 on the tip side of the vane 108 are , Contact at contact E. The pressure acting on AE on the tip side of the vane 108 is the pressure in the working chamber 110a, and the pressure acting on BE on the tip side is the pressure in the working chamber 110b. The pressure acting on the rear side CD is the suction pressure Ps that is the internal pressure of the sealed container 102.

  FIG. 13 shows the relationship between the rotation angle of the shaft 103, the differential pressure acting on the vane 108, and the position of the vane 108. The differential pressure is positive in the direction in which the vane 108 is pressed against the piston 107, and the rotation angle of the shaft 103 is based on the state in which the vane 108 is pushed most into the vane groove 104a. Considering the change in pressure in the working chambers 110a and 110b shown in FIG. 11, the balance between the pressure acting on the tip side AE and the tip side BE of the vane 108 and the pressure acting on the back side CD is balanced. Considering, a constant differential pressure indicated by F1 in FIG. 13 acts between the front end side BE and the back side CD. Further, a differential pressure corresponding to a change in the pressure in the working chamber 110a shown in FIG. 11 acts between the front end side AE and the rear side CD. The differential pressure acting on the vane 108 is the sum of these. On the other hand, the vane 108 reciprocates along the vane groove 104a in a 360 deg cycle. When the vane 108 is drawn into the vane groove 104a, the tip side of the vane 108 is pushed by the piston 107, and the tip side of the vane 108 and the piston 107 are in close contact with each other. Further, when the vane 108 is pushed out of the vane groove 104 a, the tip side of the vane 108 comes into close contact with the piston 107 due to the differential pressure acting on the vane 108.

  Next, the configuration of the conventional two-stage rotary expander shown in Patent Document 2 will be described below. 14 is a longitudinal sectional view showing a configuration of a conventional two-stage rotary expander 200, and FIG. 15 (a) is a cross-sectional view taken along line D2-D2 of the two-stage rotary expander in FIG. 15 (b) is a cross-sectional view taken along line D3-D3 of the two-stage rotary expander of FIG.

  The generator 201 includes a stator 201 a fixed to the hermetic container 202 and a rotor 201 b fixed to the shaft 203. The shaft 203 passes through a first cylinder 205 and a second cylinder 206 that are partitioned independently by an intermediate plate 204, and is rotatably supported by bearings 207 and 208. The shaft 203 is provided with a first eccentric portion 203 a and a second eccentric portion 203 b that have the same eccentric direction with respect to the axis of the shaft 203, and the first eccentric portion 203 a is arranged inside the first cylinder 205. The second piston 210 arranged inside the second cylinder 206 is fitted into the second eccentric portion 203b.

  The height and diameter of the first cylinder 205 and the first piston 209, and the second cylinder 206 and the second piston 210 are crescent-shaped spaces formed by the first cylinder 205 and the first piston 209. Is set to be smaller than the crescent-shaped space formed by the second cylinder 206 and the second piston 210. Vane grooves 205a and 206a are formed in the first cylinder 205 and the second cylinder 206, respectively. The first vane 211 and the second vane 212, which are reciprocally held by the vane grooves 205a and 206a, respectively, are in close contact with the pistons 209 and 210 due to differential pressure described later. In addition, since differential pressure does not act at the time of starting, springs 213 and 214 are supplementarily provided on the back side of the first vane 211 and the second vane 212. The crescent-shaped space formed by the first cylinder 205 and the first piston 209 is divided into two working chambers 215a and 215b by the first vane 211, and by the second cylinder 206 and the second piston 210. The formed crescent-shaped space is partitioned into two working chambers 216 a and 216 b by the second vane 212. A suction hole 205b provided in the first cylinder 205 communicates with the working chamber 215a, and the working chamber 215b and the working chamber 216a are obliquely formed on the intermediate plate 204 in the first vane 211 and the second vane 212. One space is formed by communicating with a communication hole 204a provided so as to pass between the two. The discharge hole 206b provided in the second cylinder 206 communicates with the working chamber 216b.

  The high-pressure working fluid flows into the sealed container 202 from the suction pipe 217 and is then sucked into the working chamber 215a of the first cylinder 205 through the suction hole 205b. With the rotational movement of the shaft 203, the volume of the working chamber 215a expands, and eventually, the volume moves to the working chamber 215b, and the suction stroke ends. The working chamber 215b communicates with the working chamber 216a of the second cylinder 206 through the communication hole 204a to form one working chamber, and the high-pressure working fluid has a direction in which the volume of the whole working chamber communicated increases. That is, the volume of the working chamber 215b decreases, the shaft 203 is rotated in the direction in which the volume of the working chamber 216a increases, and the generator 201 is driven. As the shaft 203 rotates, the working chamber 215b disappears, the working chamber 216a moves to the working chamber 216b communicating with the discharge hole 206b, and the expansion stroke ends. Then, the low-pressure working fluid is discharged from the discharge hole 206b to the discharge pipe 218.

  FIG. 16 shows the rotation angle of the shaft 203 and the pressures of the working chambers 215a, 215b, 216a, 216b when the two-stage rotary expander 200 of FIG. 14 is used in a refrigeration cycle using carbon dioxide as a working fluid. Show the relationship. The rotation angle of the shaft 203 is based on the state in which the first vane 211 and the second vane 212 are pushed most into the vane grooves 205a and 206a. The rotary expander 200 sucks supercritical carbon dioxide at the suction pressure Ps and discharges gas-liquid two-phase carbon dioxide at the discharge pressure Pd. Since the suction stroke is performed in the working chamber 215a, the pressure is constant at the suction pressure Ps. An expansion stroke is performed in the working chamber 215b and the working chamber 216a forming one working chamber through the communication hole 204a, and the pressure is reduced from the suction pressure Ps to the discharge pressure Pd. At that time, the pressure rapidly decreases in the first single-phase expansion, and then the pressure change becomes gentle in the expansion accompanied by the phase change. The pressure in the working chamber 216b is constant at the discharge pressure Pd because the discharge stroke is performed.

  FIG. 17A is an enlarged cross-sectional view of the vicinity of the working chamber taken along line D2-D2 of the rotary expander of FIG. A1 and B1 are edges formed by the R-shaped surface 211a and the side surface of the first vane 211, and C1 and D1 are edges formed by the back surface and the side surface of the first vane 211. The R-shaped surface 211a and the first piston 209 are in contact with each other at a contact point E1. The pressure acting on the tip side A1-E1 of the first vane 211 is the pressure in the working chamber 215a, and the pressure acting on the tip side B1-E1 is the pressure in the working chamber 215b. The pressure acting on the back side C1-D1 is the suction pressure Ps that is the internal pressure of the sealed container 202.

  FIG. 17B is an enlarged cross-sectional view of the vicinity of the working chamber taken along line D3-D3 of the rotary expander of FIG. A2 and B2 are edges formed by the R-shaped surface 212a and the side surface on the tip side of the second vane 212, and C2 and D2 are edges formed by the back surface and the side surface of the second vane 212. The R-shaped surface 212a and the second piston 210 are in contact at the contact point E2. The pressure acting on A2-E2 on the tip side of the second vane 212 is the pressure in the working chamber 216a, and the pressure acting on B2-E2 on the tip side is the pressure in the working chamber 216b. The pressure acting on the back side C2-D2 is the suction pressure Ps that is the internal pressure of the sealed container 202.

  FIG. 18A shows the relationship between the rotational angle of the shaft 203, the differential pressure acting on the first vane 211, and the position of the first vane 211. The differential pressure is positive in the direction in which the first vane 211 is pressed against the first piston 209, and the rotation angle of the shaft 203 is based on the state in which the first vane 211 is most pushed into the vane groove 205a. Yes. In consideration of changes in pressure in the working chambers 215a and 215b shown in FIG. 16, the pressure acting on the tip side A1-E1 and the tip side B1-E1 of the first vane 211 and the pressure acting on the back side C1-D1 In view of this balance, no differential pressure acts between the tip side A1-E1 and the back side C1-D1. Further, a differential pressure corresponding to a change in pressure in the working chamber 215b shown in FIG. 16 acts between the front end side B1-E1 and the back side C1-D1. On the other hand, the first vane 211 reciprocates along the vane groove 205a with a period of 360 deg. When the first vane 211 is drawn into the vane groove 205a, the front end side of the first vane 211 and the first piston 209 are pushed because the front end side of the first vane 211 is pushed by the first piston 209. In close contact. Further, when the first vane 211 is pushed out from the vane groove 205 a, the tip side of the first vane 211 is brought into close contact with the first piston 209 due to the differential pressure acting on the first vane 211.

FIG. 18B shows the relationship between the rotation angle of the shaft 203, the differential pressure acting on the second vane 212, and the position of the second vane 212. The differential pressure is positive in the direction in which the second vane 212 is pressed against the second piston 210, and the rotation angle of the shaft 203 is based on the state in which the second vane 212 is pushed most into the vane groove 206a. Yes. In consideration of changes in pressure in the working chambers 216a and 216b shown in FIG. Is considered, a constant differential pressure indicated by F2 in FIG. 18B acts between the front end side B2-E2 and the back side C2-D2. Further, a differential pressure corresponding to a change in pressure in the working chamber 216a shown in FIG. 16 acts between the front end side A2-E2 and the back side C2-D2. The differential pressure acting on the second vane 212 is the sum of these. On the other hand, the second vane 212 reciprocates along the vane groove 206a in a 360 deg cycle. When the second vane 212 is drawn into the vane groove 206a, the tip side of the second vane 212 is pushed by the second piston 210, so that the tip side of the second vane 212 and the second piston 210 are In close contact. Further, when the second vane 212 is pushed out of the vane groove 206 a, the tip side of the second vane 212 comes into close contact with the second piston 210 due to the differential pressure acting on the second vane 212.
JP-A-8-82296 JP 2005-106046 A

  In the conventional two-stage rotary expander shown in FIGS. 14 to 18, the differential pressure acting on the second vane 212 shown in FIG. 18B is applied to the vane 108 of the conventional rotary expander shown in FIG. The differential pressure acting on the first vane 211 shown in FIG. 18 (a) is very small, while acting on the vane 108 of the conventional rotary expander shown in FIG. About half of the differential pressure. When each vane 108, 211, 212 is pushed out from the respective vane groove 104a, 205a, 206a, the frictional force, its own inertial force, etc. cause the tip of each vane 108, 211, 212 to move to the respective piston 107, Although acting in the direction of separating from 209, 210, it is prevented from separating by the differential pressure. However, the conventional two-stage rotary expander has a problem in that the differential pressure acting on the first vane 211 is insufficient, and the tip side of the first vane 211 is separated from the first piston 209. .

  The present invention has been made in view of the above circumstances, and by increasing the differential pressure acting on the first vane and preventing the tip from separating from the piston, the working fluid can be manufactured at a low cost. An object of the present invention is to provide a highly efficient multistage rotary expander that prevents leakage.

  In order to solve the above-described problems, a multistage rotary expander according to the present invention includes a cylinder having a cylindrical surface inside, a shaft having an eccentric portion, and the eccentric portion, and is eccentrically rotated inside the cylinder. And a piston between the piston and the vane groove provided in the cylinder, and a space between the cylinder and the piston between the suction side space and the discharge side while being in contact with the piston with an R-shaped surface formed at the tip. A multi-stage rotary expander having n rotary-type fluid mechanisms (n is an integer of 2 or more) having a vane partitioning into a space, and operating to the suction side space of the first-stage fluid mechanism The suction hole for sucking fluid communicates with the discharge side space of the fluid mechanism at the k-th stage (k is an integer from 1 to n−1) and the suction side space of the fluid mechanism at the (k + 1) -th stage. Let one shape A communication hole, and a discharge hole for discharging the working fluid from the discharge side space of the nth stage fluid mechanism, the position of the contact point between the vane and the piston of the first stage fluid mechanism, The vane is closer to the suction side than the center line in the width direction of the vane.

  In the multistage rotary expander of the present invention, the center of curvature of the R-shaped surface of the first stage vane is offset to the suction side from the center line in the width direction of the first stage vane. It is characterized by.

  In the multi-stage rotary expander of the present invention, the position of the vane groove of the fluid machine at the first stage is based on a plane parallel to the groove including the central axis of the shaft, and the cylinder at the first stage It is characterized by being offset to the discharge side.

  The multistage rotary expander of the present invention is characterized in that the position of the contact point between the tip of the first stage vane and the first stage of the piston is always located on the R-shaped surface of the tip of the first stage vane. And

  The multistage rotary expander of the present invention is characterized in that carbon dioxide is used as a working fluid.

  According to the present invention, in the R-shaped surface on the tip side of the first vane, the area on which the pressure on the discharge side working chamber acts is larger than the area on which the pressure on the suction side working chamber acts, The difference between the tip side pressure and the back side pressure of one vane increases, so that the first vane in the conventional two-stage rotary expander is easily separated from the piston, and the working fluid leaks. A highly efficient multi-stage rotary expander can be provided.

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

(Embodiment 1)
The configuration of the multistage rotary expander 300 according to the first embodiment of the present invention is the same as that of the conventional two-stage described with reference to FIGS. 14, 15, and 17 except for the first vane 301 and the R-shaped surface 301a. The configuration is the same as that of the rotary expander 200. The same numbers are used for the same functional parts, and the description of the same configuration and operation as in the conventional example is omitted.

  FIG. 1 is a longitudinal sectional view showing a configuration of a two-stage rotary expander 300 according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along line D4-D4 of the two-stage rotary expander 300 of FIG. FIG. FIG. 3 is an enlarged cross-sectional view of the vicinity of the working chamber taken along line D4-D4 of the two-stage rotary expander 300 of FIG.

  In the conventional two-stage rotary expander 200, the R-shaped surface 211a at the tip of the first vane 211 that fits into the vane groove 205a of the first cylinder 205 is such that the center P of the R-shaped surface 211a is the first vane. In the two-stage rotary expander 300 according to the first embodiment, the shape of the first vane 301 fitted in the vane groove 205a of the first cylinder 205 is formed. The R-shaped surface 301a at the tip has a distance s (hereinafter referred to as an offset amount) on the working chamber 215a side where the suction hole 205b communicates with the center P ′ of the R-shaped surface 301a from the center line L1 in the width direction of the first vane 301. The shape is offset by s).

  By adopting such a shape, the R-shaped surface 301a at the tip of the first vane 301 and the R-shaped surface of the contact point E1 of the first piston 209 as the first piston 209 and the first vane 301 move. Since the average position of the oscillating motion on 301a is located on the suction side with respect to the center in the width direction of the first vane 301, the first position where no differential pressure is applied as compared with the conventional two-stage rotary expander 200. The distance between the edge A1 of the R-shaped surface 301a at the tip of the vane 301 and the contact E1 is shortened, and the distance between the edge B1 on which the differential pressure acts and the contact E1 is increased.

  Accordingly, in the first embodiment, since the differential pressure for bringing the front end side of the first vane 301 into close contact with the first piston 209 increases, the first vane 301 is separated from the first piston 209. Since a gap is generated and performance degradation due to leakage of working fluid from the working chamber 215a to the working chamber 215b can be prevented, a highly efficient multistage rotary expander can be provided.

  In the two-stage rotary expander 300 of the first embodiment, increasing the offset amount s at the center P ′ of the R-shaped surface 301a increases the effect of increasing the differential pressure. However, the contact point E1 between the first vane 301 and the first piston 209 swings on the R-shaped surface 301a at the tip of the first vane 301 as the first piston 209 rotates eccentrically. If the offset amount s is too large, the edge A1 on the working chamber 215a side contacts and wears the first piston 209, and the reliability decreases. The range of the offset amount s for preventing this will be described below.

  The maximum swing angle φ of the contact E1 toward the edge A1 with respect to the center line L1 of the first vane 301 can be calculated as follows with reference to FIG. The swing angle φ of the contact point E1 is maximized because the line segment P′-O ′ connecting the center P ′ of the R-shaped surface 301a and the center O ′ of the first eccentric portion 203a and the first eccentricity. This is a case where the eccentric direction OO ′ of the portion 203a forms a right angle. Φ1 in FIG. 3 is an angle formed by the center O ′ of the shaft 203 and the center O ′ of the first eccentric portion 203a as viewed from the center P ′ of the R-shaped surface 301a, and is expressed by (Equation 1). Here, r is the radius of the R-shaped surface 301a, R is the radius of the first piston 209, and ε is the amount of eccentricity of the first eccentric portion 203a.

  In FIG. 3, φ2 is an angle formed by the center line L1 of the first vane 301 and the center P ′ of the offset R-shaped surface 301a as viewed from the center O of the shaft 203, and is represented by (Equation 2). .

  The maximum swing angle φ is expressed by (Equation 3) using the angles φ1 and φ2.

  FIG. 4 is an enlarged view of the distal end portion of the first vane 301. θ is the central angle in the direction of the edge A1 viewed from the center P ′ of the R-shaped surface 301a, and is expressed by (Equation 4). Here, t is the width of the first vane 301.

  In order for the edge A1 on the working chamber 215a side not to contact the first piston 209, the center angle θ of the edge A1 only needs to be larger than the swing angle φ of the contact E1. That is, the offset amount s should satisfy (Equation 5).

  If the offset amount s is set so as to satisfy (Equation 5), it is possible to prevent the edge A1 on the working chamber 215a side from coming into contact with the first piston 209 to be damaged and worn, thereby reducing reliability. it can.

(Embodiment 2)
The configuration of the multi-stage rotary expander 400 according to the second embodiment of the present invention is the same as the conventional two-stage rotary type described with reference to FIGS. 14, 15, and 17 except for the first cylinder 401 and the vane groove 401a. The configuration is the same as that of the expander 200. The same numbers are used for the same functional parts, and the description of the same configuration and operation as in the conventional example is omitted.

  FIG. 5 is a longitudinal sectional view showing a configuration of a two-stage rotary expander 400 according to Embodiment 2 of the present invention, and FIG. 6 is a cross section taken along line D5-D5 of the two-stage rotary expander 400 of FIG. FIG. FIG. 7 is an enlarged cross-sectional view of the vicinity of the working chamber taken along line D5-D5 of the two-stage rotary expander 400 of FIG.

  The vane groove 205a of the first cylinder 205 of the conventional two-stage rotary expander 200 is disposed at a position where the center line in the width direction of the vane groove 205a passes through the center O of the shaft 203. In the second two-stage rotary expander 400, the vane groove 401 a of the first cylinder 401 is positioned at the center line L <b> 3 of the first vane 211 so that the first vane 211 of the conventional two-stage rotary expander 200. The center line L2 is offset by a distance u to the working chamber 215b side where the communication hole 204a corresponding to the discharge hole of the first cylinder 401 communicates (hereinafter referred to as an offset amount u).

  By adopting such a shape, the R-shaped surface 211a at the tip of the first vane 211 and the R-shaped surface of the contact point E1 of the first piston 209 accompanying the movement of the first piston 209 and the first vane 211. Since the average position of the oscillating motion on 211a is located on the suction side with respect to the center in the width direction of the first vane 211, compared with the conventional two-stage rotary expander 200, the first pressure differential does not act. The distance between the edge A1 of the R-shaped surface 211a at the tip of the vane 211 and the contact E1 is shortened, and the distance between the edge B1 on which the differential pressure acts and the contact E1 is increased.

  Therefore, in the second embodiment, since the differential pressure for bringing the front end side of the first vane 211 into close contact with the first piston 209 increases, the first vane 211 is separated from the first piston 209. Since a gap is generated and performance degradation due to leakage of working fluid from the working chamber 215a to the working chamber 215b can be prevented, a highly efficient two-stage rotary expander can be provided.

  In the two-stage rotary expander 400 of the second embodiment, increasing the offset amount u of the center line L3 of the first vane 211 increases the effect of increasing the differential pressure. However, the contact point E1 between the first vane 211 and the first piston 209 swings on the R-shaped surface 211a at the tip of the first vane 211 in accordance with the eccentric rotational movement of the first piston 209. If the offset amount u is too large, the edge A1 on the working chamber 215a side contacts the first piston 209 and wears down, reducing reliability. The range of the offset amount u for preventing this will be described below.

  The maximum swing angle ξ of the contact E1 toward the edge A1 with respect to the center line L3 of the first vane 211 can be calculated as follows with reference to FIG. Note that the swing angle ξ of the contact point E1 is maximized because the line segment Q′-O ′ connecting the center Q ′ of the R-shaped surface 211a and the center O ′ of the first eccentric portion 203a and the first eccentricity. This is a case where the eccentric direction OO ′ of the portion 203a forms a right angle. In FIG. 7, ξ1 is an angle formed by the center O ′ of the shaft 203 and the center O ′ of the first eccentric portion 203a as viewed from the center Q ′ of the R-shaped surface 211a, and is expressed by (Equation 6). Here, r is the radius of the R-shaped surface 211a, R is the radius of the first piston 209, and ε is the amount of eccentricity of the first eccentric portion 203a.

  In FIG. 7, ξ2 is an angle formed by a line L2 parallel to the vane groove 401a viewed from the center O of the shaft 203 and the center Q ′ of the R-shaped surface 211a, and is represented by (Equation 7). 7 is the center of the R-shaped surface 211a located on L2, which is the center line of the first vane 211 in the conventional two-stage rotary expander 200.

  The maximum swing angle ξ is expressed by (Equation 8) using the angles ξ1 and ξ2.

  FIG. 8 is an enlarged view of the distal end portion of the first vane 211. δ is a central angle in the direction of the edge A1 viewed from the center Q ′ of the R-shaped surface 211a, and is expressed by (Equation 9). Here, t is the width of the first vane 211.

  In order for the edge A1 on the working chamber 215a side not to contact the first piston 209, the center angle δ of the edge A1 only needs to be larger than the swing angle ξ of the contact E1. That is, the offset amount u only needs to satisfy (Equation 10).

  If the offset amount u is set so as to satisfy (Equation 10), it is possible to prevent the edge A1 on the working chamber 215a side from coming into contact with the first piston 209 to be damaged and worn, thereby reducing reliability. it can.

  Note that the offset of the vane groove 401a of the first cylinder 401 according to the second embodiment of the present invention and the center P ′ of the R-shaped surface 301a on the distal end side of the first vane 301 described in the first embodiment of the present invention. It goes without saying that the same effect can be obtained even if the offsets are implemented simultaneously.

  In the first and second embodiments of the present invention, when carbon dioxide is used as the working fluid, the differential pressure between the suction pressure Ps and the discharge pressure Pd increases, so the position of the contact point E1 is set to the suction-side working chamber 215a side. It goes without saying that the effect of increasing the differential pressure becomes more remarkable by moving to.

  In the first and second embodiments of the present invention, a two-stage rotary expander has been described as an example. However, even if the present invention is used for the first stage of a multistage rotary expander having three or more cylinders, the same applies. Needless to say, an effect can be obtained.

  The two-stage rotary expander of the present invention is useful as a power recovery means by recovering the expansion energy of the refrigerant in the refrigeration cycle, and is also useful as an energy recovery means from a compressive fluid other than the refrigeration cycle.

1 is a longitudinal sectional view of a two-stage rotary expander according to Embodiment 1 of the present invention. Cross section along line D4-D4 of the two-stage rotary expander shown in FIG. Enlarged cross-sectional view of the vicinity of the working chamber at line D4-D4 of the two-stage rotary expander shown in FIG. The enlarged view of the front-end | tip part of the 1st vane of the two-stage rotary expander shown in FIG. Longitudinal sectional view of a two-stage rotary expander in Embodiment 2 of the present invention Cross section along line D5-D5 of the two-stage rotary expander shown in FIG. Enlarged cross-sectional view of the vicinity of the working chamber at line D5-D5 of the two-stage rotary expander shown in FIG. The enlarged view of the front-end | tip part of the 1st vane of the two-stage rotary expander shown in FIG. Vertical section of a conventional rotary expander Cross section along line D1-D1 of the rotary expander shown in FIG. The figure which shows the relationship between the rotation angle of the shaft of the rotary type expander shown in FIG. 9, and the pressure of a working chamber. Enlarged cross-sectional view taken along line D1-D1 of the rotary expander shown in FIG. The figure which shows the relationship between the rotation angle of the shaft of the rotary expander shown in FIG. 9, the differential pressure which acts on a vane, and a vane position Vertical section of a conventional two-stage rotary expander (A) Cross section taken along line D2-D2 of the two-stage rotary expander shown in FIG. 14 (b) Cross section taken along line D3-D3 of the two-stage rotary expander shown in FIG. The figure which shows the relationship between the rotation angle of the shaft of the two-stage rotary type expander shown in FIG. 14, and the pressure of a working chamber. (A) Enlarged cross-sectional view taken along line D2-D2 of the two-stage rotary expander shown in FIG. 14 (b) Enlarged cross-sectional view taken along line D3-D3 of the 2-stage rotary expander shown in FIG. (A) FIG. 14 is a diagram showing the relationship between the rotation angle of the shaft of the two-stage rotary expander shown in FIG. 14, the differential pressure acting on the first vane, and the position of the first vane. (B) The two-stage rotary shown in FIG. The figure which shows the relationship between the rotation angle of the shaft of a type | mold expander, the differential pressure which acts on a 2nd vane, and the position of a 2nd vane

Explanation of symbols

100, 200, 300, 400 Rotary type expander 101, 201 Generator 101a, 201a Stator 101b, 201b Rotor 102, 202 Sealed container 103, 203 Shaft 103a Eccentric part 103b Axial flow path 103c Radial flow path 104 Cylinder 104a, 205a, 206a, 401a Vane groove 104b, 206b Discharge hole 105, 106, 207, 208 Bearing 105a, 205b Suction hole 105b Suction passage 107 Piston 108 Vane 108a, 211a, 212a, 301a R-shaped surface 109, 213, 214 Spring 110a, 110b, 215a, 215b, 216a, 216b Working chamber 111, 217 Suction pipe 112, 218 Discharge pipe 203a First eccentric part 203b Second eccentric part 204 Middle plate 204a Communication hole 205, 401 First cylinder 206 Second cylinder 209 First piston 210 Second piston 211, 301 First vane 212 Second vane

Claims (5)

A cylinder having an inner cylindrical surface, a shaft having an eccentric portion, a piston that fits into the eccentric portion and rotates eccentrically inside the cylinder, and a vane groove provided in the cylinder, and a tip N (n) rotary fluid mechanisms having vanes that divide the space between the cylinder and the piston into a suction-side space and a discharge-side space while being in contact with the piston on an R-shaped surface formed in a portion Is a multistage rotary expander equipped with an integer of 2 or more,
A suction hole for sucking a working fluid into the suction side space of the fluid mechanism at the first stage;
The discharge-side space of the fluid mechanism at the k-th stage (k is an integer from 1 to n−1) and the suction-side space of the fluid mechanism at the (k + 1) -th stage are connected to form one space. A communication hole,
a discharge hole for discharging the working fluid from the discharge side space of the fluid mechanism of the nth stage,
The position of the contact point between the vane and the piston of the fluid mechanism in the first stage is closer to the suction side than the center line in the width direction of the vane.
Multi-stage rotary expander. The center of curvature of the R-shaped surface of the first stage vane is offset to the suction side from the center line in the width direction of the first stage vane;
The multistage rotary expander according to claim 1. The position of the groove of the fluid mechanism at the first stage is offset to the discharge side of the fluid mechanism at the first stage with reference to a plane parallel to the vane groove including the central axis of the shaft.
The multistage rotary expander according to claim 1. The position of the R-shaped surface of the first-stage vane and the contact point of the piston is always located on the R-shaped surface of the tip of the first-stage vane.
The multistage rotary expander according to any one of claims 1 to 3. The multistage rotary expander according to any one of claims 1 to 4, wherein carbon dioxide is used as a working fluid.

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