JP2007071155A - Reciprocating cylinder device with variable compression ratio - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously change a compression ratio in a reciprocating internal combustion engine by a simple mechanism with little increase in size.
A first eccentric cam member 5 is attached to a crankpin 31 of a crankshaft 3. The first eccentric cam member 5 includes a first inner surface 51 that is rotatably fitted to the crankpin 31 and a first outer surface 52 having a symmetrical center C3 that is parallel to and eccentric from the crankpin 31. A bearing portion 42 provided at one end of the connecting rod 4 is fitted to the first outer surface 52 so as to be rotatable. Further, the second inner surface 61 of the crank disc 6 is rotatably fitted to the first outer surface 52 of the first eccentric cam member. On the other hand, a second eccentric cam member 7 that can rotate around a rotation center C6 that is coaxial with the crankshaft 3 is provided, and the second outer surface 62 of the crank disc 6 is offset from the crankshaft on the third inner surface 71 thereof. It is adapted to be rotatable around the center of rotation C4.
[Selection] Figure 3

Description

  The present invention relates to a reciprocating cylinder device in which the volume in the cylinder fluctuates as a piston reciprocates in the cylinder, and particularly relates to a reciprocating cylinder device having a variable compression ratio. Such a compression ratio variable reciprocating cylinder device can be used as, for example, a reciprocating internal combustion engine or a reciprocating compressor.

  In a gasoline engine, which is a type of reciprocating internal combustion engine, it is better to increase the compression ratio, which is the ratio between the maximum value and the minimum value of the cylinder internal volume that changes due to piston reciprocation, under a constant supply of fuel mixture gas. Generally, high output can be obtained. However, if the compression ratio is too high, knocking occurs. The range of the compression ratio at which knocking does not occur varies depending on the engine speed. Therefore, in practice, a constant compression ratio that does not cause knocking in all the rotation speed ranges is employed. If the compression ratio can be appropriately increased at a rotational speed with a sufficient allowable compression ratio, the output of the engine can be increased.

  Further, in a diesel engine which is another type of reciprocating internal combustion engine, particularly a high supercharged diesel engine, it is preferable to perform high compression only in a relatively short time before and after ignition from the viewpoint of improving fuel efficiency. Therefore, if the high compression is obtained only in a relatively narrow time range before and after ignition in the engine operating cycle, the fuel efficiency of the engine can be improved.

  Further, in the piston crank mechanism of the conventional internal combustion engine, the reciprocating motion of the piston is fast near the top dead center and slow near the bottom dead center, and the balance is lost. This causes vibration. Therefore, if a reciprocating cylinder device is developed in which the piston position change with respect to the crankshaft rotation angle is very close to a sine motion, it is possible to realize an internal combustion engine in which high-order vibrations caused by the piston reciprocating motion are unlikely to occur.

  A reciprocating piston type internal combustion engine having a variable compression ratio that can be used for the above purpose is described in Japanese Patent Laid-Open No. 9-228858 (Patent Document 1).

Moreover, in a reciprocating compressor, it is necessary to change an operating condition according to the request | requirement of the compressed gas from the demand apparatus side. Therefore, when a compressor using a motor with a rotational speed control function is used and the required amount on the demand equipment side is reduced, the amount of compressed gas discharged per unit time can be reduced by reducing the rotational speed of the motor. It is made to decrease. However, if the compressed gas discharge amount per unit time can be changed by changing the compression ratio without using such rotation speed control, a simple constant speed motor can be used.
JP-A-9-228858

  However, in the variable compression ratio reciprocating cylinder device of the internal combustion engine described in Patent Document 1, in order to make the compression ratio of the piston variable, the crankshaft and the connecting rod are not directly connected but a plurality of links are connected. Are connected through. This mechanism uses a Stevenson type plane six-joint link mechanism having one straight pair, and transmits the reciprocating motion of the piston to the crankshaft of the rotary swing type four-joint link mechanism via a connecting rod. Is. For this reason, there are disadvantages in that the size of the apparatus is increased and countermeasures against vibration and noise caused by the swinging motion are required.

  In view of the technical problems as described above, the present invention continuously reduces the compression ratio in a reciprocating cylinder device such as a reciprocating internal combustion engine or a reciprocating compressor as described above by a simple mechanism with little increase in size. The purpose is to change.

According to the present invention, the object as described above is achieved.
A reciprocating cylinder device comprising a cylinder, a piston that reciprocates in the cylinder, a crankshaft, and a connecting rod for transmitting a driving force between the crankshaft and the piston,
A first eccentric cam member is attached to the crankpin of the crankshaft, the first eccentric cam member being parallel to the crankpin and a first inner surface that is rotatably adapted to the crankpin. A first outer surface having a symmetrical center eccentric from the crankpin, and a bearing portion provided at one end of the connecting rod is rotatably adapted to the first outer surface;
A second eccentric cam member rotatable about a rotation center coaxial with or parallel to the crankshaft is provided;
A crank disk that is rotatable with respect to both the first eccentric cam member and the second eccentric cam member is provided, and the crank disk is rotatable on a first outer surface of the first eccentric cam member. And a reciprocating cylinder device having a variable compression ratio, wherein the second eccentric cam member is adapted to be rotatable about a rotation center eccentric from the crankshaft with respect to the second eccentric cam member. ,
Is provided.

  In one aspect of the present invention, the second eccentric cam member includes a third inner surface having the rotational center as a symmetric center, and the crank disk is rotatable on the third inner surface of the second eccentric cam member. A matching second outer surface is provided. In one aspect of the present invention, the second eccentric cam member is provided with a compression ratio control member, and the rotation position of the second eccentric cam member with respect to the crankshaft is set via the compression ratio control member. By doing so, the compression ratio of the reciprocating motion of the piston in the cylinder is set.

  In one aspect of the present invention, the compression ratio variable reciprocating cylinder device is an internal combustion engine in which a fuel gas mixture is burned and exploded in the cylinder, and the connecting rod has a driving force for the reciprocating motion of the piston. The crank shaft is transmitted to the crank pin of the crank shaft through the first eccentric cam member, thereby rotating the crank shaft. In one aspect of the present invention, the variable compression ratio reciprocating cylinder device is a compressor that discharges compressed gas obtained by compressing suction gas in the cylinder, and the connecting rod is a rotational drive source. Is transmitted to the piston via the first eccentric cam member, thereby causing the piston to reciprocate within the cylinder.

  In one aspect of the present invention, the second eccentric cam member is rotatable about a rotation center coaxial with the crankshaft, the crankshaft, the first eccentric cam member, the crank disc, The second eccentric cam member constitutes a double rotation type link mechanism.

  According to the compression ratio variable reciprocating cylinder device of the present invention, both the bearing portion of the connecting rod and the second inner surface of the crank disc can be rotated on the first outer surface of the first eccentric cam member attached to the crank pin. Since the second eccentric cam member is adapted to be rotatable with respect to the crank disc, the change in the piston position with respect to the crankshaft rotation angle can be made very close to a sine motion, and further the dimensions of the device It is possible to continuously change the piston reciprocating range and further the compression ratio by a simple mechanism with a small increase in the amount of.

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

  FIG. 1 is a schematic sectional view of an internal combustion engine as an embodiment of a compression ratio variable reciprocating cylinder device according to the present invention, FIG. 2 is a schematic sectional view thereof, and FIG. 3 is a schematic exploded view thereof.

  As shown in FIGS. 1 to 3, a piston 2 is adapted to reciprocate in a vertical direction in a cylinder 1 arranged in the vertical direction. The symmetry center line of the cylinder 1 (that is, the symmetry center line of the piston 2) is C7. The piston 2 has a piston pin 21 in the horizontal direction. A pipe for introducing a fuel mixture gas and a pipe for discharging a combustion gas are connected to the upper portion of the cylinder 1 via an intake valve and an exhaust valve, respectively. Although an ignition device for igniting is arranged, these are not shown.

  On the other hand, a crankshaft 3 for obtaining the rotational output of the internal combustion engine is disposed horizontally below the cylinder 1. The crankshaft 3 is supported so as to be rotatable about the rotation center C1, and has a crankpin 31 positioned parallel to the rotation center C1 and separated from the rotation center C1 by an appropriate distance. The center of rotational symmetry of the crankpin is C2.

  A connecting rod 4 is provided to transmit driving force from the piston pin 21 to the crankshaft 3. The connecting rod 4 has bearing portions 41 and 42 which are parallel to each other at one end (upper end) and the other end (lower end), and one bearing 41 is parallel to the crankshaft 3. Fits piston pin 21. The rotational symmetry center of the piston pin 21 is C5.

  A first eccentric cam member 5 is attached to the crankpin 31. The first eccentric cam member 5 includes an inner surface (first inner surface) 51 serving as a bearing portion that is rotatably fitted to the crankpin 31 and a symmetrical center (first shaft) parallel to the crankpin 31 and eccentric from the crankpin. 1 symmetric center) an outer surface (first outer surface) 52 having C3. The other bearing portion 42 of the connecting rod 4 is adapted to be rotatable on the outer surface 52.

  Further, the second eccentric cam member 7 is rotatable around a rotation center C6 that is coaxial with or parallel to the crankshaft 3 and appropriately separated. That is, the journal part 72 of the second eccentric cam member 7 is formed to be rotationally symmetric with respect to the rotation center C6, and the journal part 72 is supported. The second eccentric cam member 7 has a function for making the reciprocating range of the piston 2 and the compression ratio variable as will be described later. The second eccentric cam member 7 includes an inner surface (third inner surface) 71 having a symmetry center (second symmetry center) C4 that is parallel to the crankshaft 3 and eccentric from the crankshaft.

  Further, the crank disk 6 is adapted to be rotatable with respect to both the first eccentric cam member 5 and the second eccentric cam member 7. That is, the crank disc 6 includes an inner surface (second inner surface) 61 that is adapted to rotate around the center of symmetry C3 with respect to the outer surface 52 of the first eccentric cam member 5. In addition, the crank disk 6 includes an outer surface (second outer surface) 62 that is adapted to rotate around the center of symmetry C4 with respect to the inner surface 71 of the second eccentric cam member 7.

  The second eccentric cam member 7 is provided with a compression ratio control member 73 that protrudes radially outward. By setting the rotational position of the second eccentric cam member 7 with respect to the crankshaft 3, the reciprocating range of the piston 2 in the cylinder 1 and thus the compression ratio can be set. Therefore, the compression ratio control member 73 is moved in the circumferential direction around the rotation center C1 of the crankshaft 3 or the rotation center C6 of the second eccentric cam member 7. The movement angle range of the compression ratio control member 73 is about 90 ° clockwise or counterclockwise. The compression ratio control member 73 is engaged with an action portion of the control means (not shown), and the angle position can be changed by a command from the control means in accordance with a mode predetermined in relation to the piston position in the cylinder. it can. It should be noted that such a compression ratio control mode can be appropriately set according to the type of the fuel mixture gas.

  As can be seen from the above description, the centers C1 to C6 are parallel to each other, and the center C7 is orthogonal to the center C5.

  The operation of this embodiment will be described below.

  FIG. 4 is a schematic diagram showing a state in which the arrangement of the center C4 with respect to the center C1 is different from that in FIG. 1 to 4 show a case where the second eccentric cam member 7 rotates coaxially with the crankshaft 3, that is, a case where the center C6 coincides with the center C1. In this case, the rotation position of the second eccentric cam member 7 with respect to the crankshaft 3 is shown in FIG. 1 as the first position where the center C4 is located directly beside the center C1 as shown in FIG. As described above, the center C4 can be changed within a range of 90 degrees with respect to the second position located directly below the center C1. As will be described later, when the second eccentric cam member 7 is in the first rotational position, the first piston reciprocating range and the maximum compression ratio are obtained, and the second eccentric cam member 7 is in the second rotational position. In some cases, a second piston reciprocating range and minimum compression ratio are obtained.

  In FIG. 4, when the center C5 of the piston pin 21 reciprocates in the vertical direction along the center C7 of the cylinder 1, the center C3 of the outer surface 52 of the first eccentric cam member 5 goes around the circular track T3, and the crank The center C2 of the pin 21 goes around the circular track T2. That is, in the present embodiment, a double rotation type component four-bar linkage mechanism is used. Even in the state shown in FIG. 1, it is clear that the center C3 goes around a circular path and the center C2 goes around a circular path.

  Fig.5 (a) shows arrangement | positioning of each center C1-C5 when a piston is located in a top dead center in the state in which the maximum compression ratio is obtained. At this time, the center C5 is at the vertical position S1, and the center C5, the center C3, and the center C4 are located in this order and in the same plane from above. FIG.5 (b) shows arrangement | positioning of each center C1-C5 when a piston is located in a bottom dead center in the state in which the maximum compression ratio is obtained. At this time, the center C5 is in the vertical position S2, and the center C5, the center C4, and the center C3 are located in this order and in the same plane from above. The stroke of piston reciprocation is | S1-S2 |. This length is approximately equal to twice the distance between the center C3 and the center C4, and in a preferred embodiment described below, is approximately equal to twice the distance between the center C1 and the center C2.

  FIG. 6 shows a minimum compression ratio state in which the arrangement of the center C4 with respect to the center C1 is as shown in FIG. FIG. 6A shows the arrangement of the centers C1 to C5 when the piston is located at the top dead center in a state where the minimum compression ratio is obtained. At this time, the center C5 is in the vertical position S3, and the center C5, the center C3, and the center C4 are located in this order and in the same plane from above. FIG. 6B shows the arrangement of the centers C1 to C5 when the piston is located at the bottom dead center in a state where the minimum compression ratio is obtained. At this time, the center C5 is in the vertical direction position S4, and the center C5, the center C4, and the center C3 are located in this order and in the same plane from above. The stroke of piston reciprocation is | S3-S4 |, which is substantially equal to | S1-S2 |.

  As can be seen from the above description, the position S3 is lower than the position S1 by a distance between C1 and C4. Accordingly, the compression ratio in the states of FIGS. 6A and 6B is smaller than the compression ratio in the states of FIGS. 5A and 5B. When the compression ratio control member 73 is set to an angular position between the state of FIGS. 5A and 5B and the state of FIGS. 6A and 6B by the compression ratio control means, That is, when the rotational direction position of the center C4 with respect to the center C1 exists between the position shown in FIG. 4 and the position shown in FIG. 1, a compression ratio between the maximum compression ratio and the minimum compression ratio is obtained. .

  FIG. 7 shows an outline of the motion region of the link mechanism when the piston reciprocation range is S, which is in the minimum compression ratio state, in the apparatus of the embodiment of the present invention as described above. FIG. 8 shows an outline of the motion region of the link mechanism when the piston reciprocating range is S in an apparatus using a conventional rotary oscillating planar four-joint link mechanism. In FIG. 8, T2 ′ represents the rotational symmetry center of the crankpin, T3 ′ represents the center of the shaft fitted to the bearing at the lower end of the connecting rod, and Tx was fitted to the bearing at the tip of the swing arm. Indicates the center of the axis. Comparing FIG. 7 and FIG. 8, it can be seen that the embodiment of the present invention has a smaller movement region and therefore the size of the apparatus can be reduced as compared with the apparatus using the conventional link mechanism.

  Next, FIG. 9 shows an example of the relationship between the crankshaft rotation angle and the piston position in the embodiment of the present invention as described above. The output curve of the piston position is very close to a sine curve. On the other hand, FIG. 10 shows an example of the relationship between the crankshaft rotation angle and the piston position in the conventional apparatus. The output curve of the piston position has a larger deviation from the sine curve than that of FIG.

  If the suitable specific example of the dimension [arbitrary unit] of the link mechanism in this embodiment as described above is shown, the distance between C1 and C2 is 50, the distance between C2 and C3 is 10 to 20, and the distance between C3 and C4 is 48. -52, the distance between C4-C1 is 5-12, the distance between C3-C5 is 150, and the distance between C1-C7 (d of FIG. 4) is -20-20. Thus, the distance between C3 and C4 is substantially the same as the distance between C1 and C2, is approximately 8 times the distance between C4 and C1, and the distance between C2 and C3 is approximately 2.5 times the distance between C4 and C1. Thus, the output curve of the piston position can be reduced from the sine curve.

  In the compression ratio variable reciprocating cylinder device of the present invention described in relation to the above embodiment, the component four-bar linkage mechanism including the C1-C2 node, the C2-C3 node, the C3-C4 node, and the C4-C1 node is provided. Since it is a double rotation type, the size of the apparatus can be made sufficiently smaller than that using the conventional rotation / oscillation type link mechanism. Since the compression ratio can be freely and continuously changed by changing the rotational direction position of the center C4 with respect to the center C1, the engine operating conditions such as the output rotational speed are input to the compression ratio control means, According to this operating condition, an operation with an increased compression ratio is possible within a range where knocking does not occur, and an improvement in engine output is realized. In addition, there is less vibration and noise than those using the conventional rotary swing type link mechanism.

  The compression ratio of the fuel gas mixture is typically determined for one cycle of reciprocation as described above. However, apart from the compression ratio resulting from one cycle of reciprocation, a virtual compression ratio that can be varied within one cycle of reciprocation can be defined. That is, since the change in state can be realized by changing the angular position of the compression ratio control member 73, the compression ratio when one cycle of reciprocation is executed at each angular position of the compression ratio control member 73 It can be defined as a virtual compression ratio at the angular position. In the present invention, the virtual compression ratio can be changed by changing the angular position of the compression ratio control member 73 within one cycle of reciprocation. Therefore, for example, in a high-supercharged diesel engine, a high compression ratio is achieved only in a relatively short time before and after ignition for each cycle, and fuel consumption is improved by appropriately reducing the compression ratio at other times. Is possible.

  In the above embodiment, a reciprocating internal combustion engine in which a fuel mixture gas is burned and exploded in the cylinder is employed as the variable compression ratio reciprocating cylinder device. Here, the connecting rod is a driving force for the reciprocating movement of the piston. Is transmitted to the crankshaft via the first eccentric cam member, thereby rotating the crankshaft.

  However, the present invention is not limited to this, and can be applied to other compression ratio variable reciprocating cylinder devices. As such a device, for example, a reciprocating compressor in which compressed gas obtained by compression of suction gas in a cylinder is discharged can be mentioned. In this case, the connecting rod transmits the driving force of the rotational movement of the crankshaft by the rotational drive source to the piston via the first eccentric cam member, thereby reciprocating the piston in the cylinder. A pipe for introducing compressed gas and a pipe for discharging compressed gas are connected to the upper part of the cylinder via valves. According to this compression ratio variable reciprocating compressor, the compression ratio can be freely and continuously changed by the compression ratio control means with a simple mechanism with little increase in apparatus size and low vibration and noise. Using a simple constant speed motor as a rotational drive source, input the demand for compressed gas from the demand equipment side to the compression ratio control means, and realize an appropriate discharge amount per unit time accordingly Can do.

1 is a schematic cross-sectional view of an internal combustion engine as an embodiment of a variable compression ratio reciprocating cylinder device according to the present invention. It is typical sectional drawing of embodiment of FIG. FIG. 2 is a schematic exploded view of the embodiment of FIG. 1. It is a schematic diagram of embodiment of FIG. It is operation | movement explanatory drawing in the state in which the maximum compression ratio of embodiment of FIG. 1 is obtained. It is operation | movement explanatory drawing in the state in which the minimum compression ratio of embodiment of FIG. 1 is obtained. It is a schematic diagram which shows the outline of the motion area | region of the link mechanism of embodiment of FIG. It is a schematic diagram which shows the outline of the motion area | region of the link mechanism of the conventional compression ratio variable reciprocating cylinder apparatus. It is a figure which shows an example of the relationship between the crankshaft rotation angle and piston position in embodiment of FIG. It is a figure which shows an example of the relationship between the crankshaft rotation angle and piston position in the conventional reciprocating cylinder apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 21 Piston pin 3 Crankshaft 31 Crankpin 4 Connecting rod 41, 42 Bearing part 5 1st eccentric cam member 51 1st inner surface 52 1st outer surface 6 Crank disc 61 2nd inner surface 62 2nd outer surface 7 2nd Eccentric cam member 71 Third inner surface 72 Journal portion 73 Compression ratio control member C1 Center of rotation of crankshaft C2 Center of rotational symmetry of crankpin C3 Center of symmetry of first outer surface of first eccentric cam member C4 Third of second eccentric cam member Center of symmetry of inner surface C5 Center of symmetry of piston pin C6 Center of rotation of second eccentric cam member C7 Center of symmetry of cylinder

Claims (6)

A reciprocating cylinder device comprising a cylinder, a piston that reciprocates in the cylinder, a crankshaft, and a connecting rod for transmitting a driving force between the crankshaft and the piston,
A first eccentric cam member is attached to the crankpin of the crankshaft, the first eccentric cam member being parallel to the crankpin and a first inner surface that is rotatably adapted to the crankpin. A first outer surface having a symmetrical center eccentric from the crankpin, and a bearing portion provided at one end of the connecting rod is rotatably adapted to the first outer surface;
A second eccentric cam member rotatable about a rotation center coaxial with or parallel to the crankshaft is provided;
A crank disk that is rotatable with respect to both the first eccentric cam member and the second eccentric cam member is provided, and the crank disk is rotatable on a first outer surface of the first eccentric cam member. And a reciprocating cylinder device having a variable compression ratio, wherein the second eccentric cam member is adapted to be rotatable about a rotation center eccentric from the crankshaft with respect to the second eccentric cam member. . The second eccentric cam member has a third inner surface with the rotational center as a center of symmetry, and the crank disc has a second outer surface that is rotatably fitted to the third inner surface of the second eccentric cam member. The compression ratio variable reciprocating cylinder device according to claim 1, wherein the compression ratio variable reciprocating cylinder device is provided. The second eccentric cam member is provided with a compression ratio control member, and by setting the rotational position of the second eccentric cam member with respect to the crankshaft via the compression ratio control member, The compression ratio variable reciprocating cylinder device according to claim 1, wherein the compression ratio of the reciprocating motion of the piston is set. The compression ratio variable reciprocating cylinder device is an internal combustion engine in which a fuel gas mixture burns and explodes in the cylinder, and the connecting rod transmits the driving force of the piston reciprocating via the first eccentric cam member. 4. The compression ratio variable reciprocating cylinder device according to claim 1, wherein the cylinder shaft is transmitted to a crankpin of the crankshaft, thereby rotating the crankshaft. The compression ratio variable reciprocating cylinder device is a compressor to which compressed gas obtained by compressing suction gas in the cylinder is discharged, and the connecting rod is used for rotational movement of the crankshaft by a rotational drive source. 4. The driving force is transmitted to the piston via the first eccentric cam member, and thereby the piston is reciprocated in the cylinder. Reciprocating cylinder device with variable compression ratio. The second eccentric cam member is rotatable about a rotation center coaxial with the crankshaft, and the crankshaft, the first eccentric cam member, the crank disc, and the second eccentric cam member are two. The compression ratio variable reciprocating cylinder device according to any one of claims 1 to 5, wherein a double rotation type link mechanism is configured.

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