JP6493704B2 - Variable compression ratio device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable compression ratio device for an internal combustion engine.

  In an internal combustion engine, a variable compression ratio device capable of changing the compression ratio is known in order to achieve high efficiency and low fuel consumption. In the variable compression ratio apparatus, for example, an eccentric sleeve is rotatably inserted between the large end of the connecting rod and the crank pin of the crankshaft, and the eccentric sleeve is rotated by the rotation of the crankshaft. By rotating the eccentric sleeve, the position of the crankpin with respect to the support hole of the connecting rod is switched, and the state of the high compression ratio and the state of the low compression ratio are switched (for example, see Patent Documents 1 and 2).

  When the compression ratio state is fixed, the rotational position of the eccentric sleeve is fixed using a stopper or the like that is mechanically operated at a predetermined rotational position. Further, the frictional force of the eccentric sleeve against the support hole of the connecting rod is increased by the hydraulic pressure, and the rotational position of the eccentric sleeve is fixed.

  However, since the rotation of the eccentric sleeve depends on the rotation of the crankshaft (the operating state of the internal combustion engine), the rotation direction is one direction and the inertial force is likely to work. The rotational speed of the eccentric sleeve changes due to the combustion pressure. For this reason, when the rotational position of the eccentric sleeve is fixed and the compression ratio is fixed, the responsiveness for fixing the rotational position may change and the rotational position of the eccentric sleeve may not be accurately fixed. It was a fact.

JP-A-6-241058 JP 2000-64866 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a variable compression ratio device for an internal combustion engine that can reliably control the rotational position of the eccentric sleeve to a desired rotational position.

In order to achieve the above object, a variable compression ratio device for an internal combustion engine according to claim 1 of the present invention is such that a support hole of a small end is pivotally supported on a support shaft of a piston that reciprocates in a cylinder, and a crankshaft A connecting rod in which a support hole of a large end is pivotally supported by a support shaft of the support shaft, and the small end or the support hole of the large end and the support shaft are rotatably interposed, and the small end Or an eccentric sleeve for displacing the central axis of the support hole of the support shaft or the large end portion with respect to the central axis of the support shaft, and an actuator for rotationally driving the eccentric sleeve, and the large end portion of the connecting rod is A rod-side end formed on the rod-side end and forming the upper half of the support hole; and a semicircular body forming the lower half of the support hole and fixed to the rod-side end And having a cap A fixing pin is provided in a state of being projected and urged toward the support hole side at the end of the lid side, and the fixing pin is provided on the outer peripheral surface of the eccentric sleeve when the compression sleeve is brought into a high compression ratio state. A first fitting groove to be fitted and a second fitting groove to which the fixing pin is fitted when being brought into a low compression ratio state are provided, and the actuator is arranged on the inner side of the cap, the eccentric sleeve. It has the hydraulic chamber provided over the both ends of the circumferential direction in the location which opposes, and the said hydraulic chamber is provided only inside the said cap, It is characterized by the above-mentioned.

  According to the first aspect of the present invention, the eccentric sleeve is driven to rotate by the actuator, whereby the center axis of the support hole at the small end or the large end is displaced with respect to the center axis of the support shaft, thereby moving the piston. The state is switched to a high compression ratio state or a low compression ratio state.

  For this reason, the rotational position of the eccentric sleeve can be reliably controlled to a desired rotational position.

  The variable compression ratio device for an internal combustion engine according to a second aspect of the present invention is the variable compression ratio device for an internal combustion engine according to the first aspect, wherein the actuator is configured to decenter the oil pressure applied to the hydraulic chamber. And a control means for controlling the rotation of the eccentric sleeve by controlling the hydraulic pressure applied to the hydraulic chamber.

  In the present invention according to claim 2, the eccentric sleeve is rotated by the hydraulic pressure via the transmission means (for example, the vane integrated with the eccentric sleeve) by applying the hydraulic pressure to the hydraulic chamber based on the command of the control means.

  The transmission means plays the role of the piston of the cylinder, supplies the hydraulic pressure to one hydraulic chamber sandwiching the transmission means, and simultaneously discharges the hydraulic pressure from the other hydraulic chamber and controls the discharge status, thereby controlling the rotational position of the eccentric sleeve. It is preferable to perform control.

  A variable compression ratio device for an internal combustion engine according to a third aspect of the present invention is the variable compression ratio device for an internal combustion engine according to the second aspect, wherein the eccentric sleeve is a support hole in the large end portion of the connecting rod. And a support shaft of the crankshaft.

  According to the third aspect of the present invention, the eccentric sleeve can be rotated hydraulically by providing a hydraulic chamber on the large end side of the connecting rod. The hydraulic chamber can be provided in the connecting rod or the eccentric sleeve.

  According to a fourth aspect of the present invention, there is provided the variable compression ratio device for an internal combustion engine according to the third aspect, wherein the hydraulic chamber is the support of the large end portion of the connecting rod. It is formed in a hole.

  In the present invention according to claim 4, the eccentric sleeve can be rotated by hydraulic pressure by providing a hydraulic chamber in a support hole (for example, inside of the cap, inside of the rod side end) of the connecting rod.

  The variable compression ratio device for an internal combustion engine according to the present invention makes it possible to reliably control the rotational position of the eccentric sleeve to a desired rotational position.

It is an external view of the principal part of the variable compression ratio apparatus of the internal combustion engine which concerns on one Example of this invention. It is a disassembled perspective view of a connecting rod. It is sectional drawing of a connecting rod. It is sectional drawing of the big end part of a connecting rod. It is a schematic system diagram of a hydraulic circuit. It is operation | movement explanatory drawing of switching of a compression ratio. It is operation | movement explanatory drawing of switching of a compression ratio.

  A variable compression ratio device for an internal combustion engine according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is an external view illustrating a main part of a variable compression ratio apparatus for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is an external view illustrating a disassembled connecting rod, and FIG. The cross section of the connecting rod in the compression ratio state is shown in FIG. 3B, and the cross section of the connecting rod in the low compression ratio state is shown.

  As shown in FIG. 1, a crank journal 4 of a crankshaft 3 is rotatably supported by a cylinder block (only the lower block 2 is shown) of an internal combustion engine.

  As shown in FIGS. 1 and 2, the large end portion 6 of the connecting rod 10 is rotatably supported on the crankpin 5 (support shaft) of the crankshaft 3. That is, the support hole of the large end portion 6 of the connecting rod 10 is pivotally supported by the support shaft. A support shaft of a piston 8 that reciprocates in the cylinder is rotatably supported on the small end portion 7 of the connecting rod 10. That is, the support hole of the small end portion 7 of the connecting rod 10 is pivotally supported on the support shaft of the piston 8.

  When the piston 8 reciprocates in the cylinder, the crankshaft 3 rotates around the crank journal 4 via the connecting rod 10. That is, the connecting rod 10 transmits the reciprocating movement of the piston 8 as the rotational force of the crankshaft.

  The outer peripheral surface of the eccentric sleeve 11 is rotatably supported in the support hole of the large end portion 6 of the connecting rod 10, and the inner peripheral surface of the eccentric sleeve 11 is rotatable on the outer peripheral surface of the crankpin 5 of the crankshaft 3. It is supported. The eccentric sleeve 11 is provided with a thick portion 11a and a thin portion 11b facing each other in the circumferential direction, and the thickness is gradually changed.

  The large end 6 of the connecting rod 10 incorporates an actuator 12 that rotationally drives the eccentric sleeve 11. Although specifically described later, by rotating the eccentric sleeve 11 by the actuator 12, the center of the crankpin 5 of the crankshaft 3 and the center of the large end portion 6 of the connecting rod 10 are eccentric, and the piston 8 (FIG. 1). (See) is switched to a high compression ratio state or a low compression ratio state.

  In other words, driving at a high compression ratio is advantageous to improve thermal efficiency and fuel efficiency, while knocking may occur when driving at a high compression ratio during high load operation. It can be operated at a high compression ratio at times. For this reason, by driving the actuator 12 and rotating the eccentric sleeve 11 according to the operating state, the state is switched to a high compression ratio state or a low compression ratio state as shown in FIG.

  As shown in FIG. 3A, the rotational position of the eccentric sleeve 11 in a state where the thick portion 11a is located is in a high compression ratio state. As shown in FIG. 3B, the rotational position of the eccentric sleeve 11 with the thin portion 11b on the upper side is in a low compression ratio state.

  That is, as shown in FIG. 3, the high compression ratio state (a) in which the thick portion 11a of the eccentric sleeve 11 is above is the low compression ratio state (b) in which the thin portion 11b of the eccentric sleeve 11 is above. As compared with the above, the position (moving state) of the top dead center of the piston 8 is higher by the height h.

  For example, since the low compression ratio state is at the time of high load operation, switching from the high compression ratio state to the low compression ratio state is a change from low load operation to high load operation, which is high Responsiveness is required.

  For this reason, when switching from the high compression ratio state to the low compression ratio state, the eccentric sleeve 11 is rotated in a direction in which the accompanying force is exerted by the rotation of the crankshaft 3, and the eccentric sleeve 11 is moved in a highly responsive state. I try to rotate it. When switching from the low compression ratio state to the high compression ratio state, high responsiveness is not required, so that the driving range of the actuator 12 is not increased more than necessary, and the rotation direction of the crankshaft 3 is reversed. The eccentric sleeve 11 is rotated in the direction.

  Since the actuator 12 is driven to rotate the eccentric sleeve 11, the rotational position of the eccentric sleeve 11 can be reliably controlled to a desired rotational position.

  The control means for controlling the rotation of the actuator 12 and the eccentric sleeve 11 will be specifically described with reference to FIGS. 2, 4, and 5.

  FIG. 4 shows a cross section of the large end of the connecting rod, and FIG. 5 shows a schematic system of the hydraulic circuit.

  As shown in FIGS. 2 and 4, the large end portion 6 of the connecting rod 10 is provided with a hydraulic chamber 13 for an actuator 12 that rotationally drives the eccentric sleeve 11. That is, the large end portion 6 of the connecting rod is formed at the end portion on the rod side, forms the upper half of the support hole (formed in a semicircular shape), and the bottom end portion of the support hole. And a semicircular cap 16 that forms a half on the side and is fixed to the rod side end 15.

  A hydraulic chamber 13 having a U-shaped cross section (see FIG. 2) is provided inside the cap 16 (support hole). The hydraulic chamber 13 is provided across both ends in the circumferential direction inside the cap 16. In other words, the hydraulic chamber 13 is formed in a portion excluding a portion where the rod-side end portion 15 of the large end portion 6 of the connecting rod 10 and the cap 16 are divided.

  Since the hydraulic chamber 13 is formed in a portion excluding the divided portion between the rod side end portion 15 of the large end portion 6 of the connecting rod 10 and the cap 16, the hydraulic oil to the hydraulic chamber 13 is formed in a divided portion that can be easily processed. Supply paths and discharge paths can be formed. In addition, since the hydraulic chamber 13 is formed in the cap 16, it is not necessary to form a hydraulic chamber in the rod side end portion 15, and even if the hydraulic chamber 13 is provided in the large end portion 6, Rigidity can be maintained without reinforcing the boundary portion of the portion 15 with the rod portion.

  And since the hydraulic chamber 13 is provided over the both ends of the circumferential direction inside the cap 16, the eccentric sleeve 11 can be rotationally driven by the actuator 12 at an angle of about 180 degrees. For this reason, the amount of eccentricity of the eccentric sleeve 11 can be set in a wide rotation range.

  In addition, although the hydraulic chamber 13 was formed over the both ends of the cap 16, it can be set as the hydraulic chamber of the arbitrary circumference length of the cap 16 according to the eccentric condition of the eccentric sleeve. Further, it is possible to provide a hydraulic chamber at the rod side end 15, and it is also possible to provide a hydraulic chamber across the cap 16 and the rod side end 15. Furthermore, it is possible to provide a hydraulic chamber on the eccentric sleeve 11 side.

  A vane 17 serving as a transmission means is provided at a portion corresponding to the boundary between the thick portion 11a and the thin portion 11b on the outer peripheral portion of the eccentric sleeve 11. The vane 17 is formed in a U shape corresponding to the cross-sectional shape of the hydraulic chamber 13 and is disposed in the hydraulic chamber 13. The hydraulic chamber 13 is divided into two chambers by the vane 17.

  Eccentric sleeve 11 rotates in one direction by supplying hydraulic pressure to one chamber and discharging hydraulic pressure from the other chamber, and eccentric sleeve by supplying hydraulic pressure to the other chamber and discharging hydraulic pressure from the other chamber. 11 rotates in the other direction.

  That is, the vane 17 serving as a transmission means plays the role of a piston of the cylinder, supplies the hydraulic pressure to one hydraulic chamber 13 sandwiching the vane 17 and simultaneously discharges the hydraulic pressure from the other hydraulic chamber 13 to control the discharge state. Thus, the rotational position of the eccentric sleeve 11 is controlled. In other words, the hydraulic chamber 13 and the vane 17 are built in the cap 16 to constitute the actuator 12, and the rotational position of the eccentric sleeve 11 is controlled.

  When the rotation direction of the crankshaft 3 (see FIG. 1) is the clockwise direction in FIG. 4 (when the movement direction of the crankpin 5 is the direction of the white arrow in the figure), the thick portion 11a of the eccentric sleeve 11 However, the vane 17 is arranged in the hydraulic chamber 13 in a state where the right half in the drawing is rotated and arranged vertically and the thin portion 11b is arranged in the vertical direction by rotating the left half in the drawing.

  As shown in FIG. 4, simultaneously with supplying the hydraulic pressure from the vane 17 to the right hydraulic chamber (one hydraulic chamber 13a) on the thick wall portion 11a side, the hydraulic chamber on the thin wall portion 11b side on the left side in the drawing. By discharging the hydraulic pressure from (the other hydraulic chamber 13b), the eccentric sleeve 11 is rotated in the clockwise direction in the drawing, so that the thin portion 11b is in a low compression ratio state.

  That is, when switching from a high compression ratio state to a low compression ratio state, the eccentric sleeve 11 is rotated in a direction in which a rotating force is exerted by the rotation of the crankshaft 3 (see FIG. 1), and the responsiveness is high. The eccentric sleeve 11 is rotated.

  On the contrary, when the hydraulic pressure is supplied to the other hydraulic chamber 13b and the hydraulic pressure is discharged from the one hydraulic chamber 13a, the eccentric sleeve 11 rotates counterclockwise in the drawing, that is, the crankshaft 3 (see FIG. 1). Rotating in the opposite direction with respect to the rotation direction, the thick portion 11a is placed in a high compression ratio.

  That is, when switching from the low compression ratio state to the high compression ratio state, high responsiveness is not required, so the eccentric sleeve 11 is rotated in the opposite direction to the rotation direction of the crankshaft 3 (see FIG. 1). Yes.

  As shown in FIG. 4, a fixing pin 28 is provided on the rod-side end portion 15 in a state of being urged toward the support hole. That is, the fixing pin 28 is provided on the rod side end portion 15 in a state where the tip of the fixing pin 28 is in sliding contact with the circumferential surface of the eccentric sleeve 11. A fitting groove 29 into which the tip of the fixing pin 28 is fitted is formed on the outer peripheral surface of the eccentric sleeve 11.

  When the thick sleeve portion 11a of the eccentric sleeve 11 is in a high compression ratio state, the fitting groove 29a faces the fixing pin 28 and the fixing pin 28 fits into the fitting groove 29a so that the high compression ratio is achieved. The state of is fixed. When the thin-walled portion 11b of the eccentric sleeve 11 is in a high compression ratio state, the fitting groove 29b faces the fixing pin 28 and the fixing pin 28 is fitted in the fitting groove 29b so that the low compression ratio is obtained. The state is fixed.

  When the compression ratio is changed, the fitting of the fixing pin 28 is released from one fitting groove 29 (fitting groove 29a) by a mechanism (not shown). Then, by rotating the eccentric sleeve 11, the fixing pin 28 is fitted into the other fitting groove 29 (fitting groove 29b) to fix the changed compression ratio state.

  A mechanism for controlling the rotation of the eccentric sleeve 11 will be specifically described with reference to FIGS. 1, 4, and 5.

  As shown in FIGS. 4 and 5, the first discharge port 21 communicates with the end portion of the hydraulic chamber 13 on the one hydraulic chamber 13a side, and the end portion of the hydraulic chamber 13 on the other hydraulic chamber 13b side has the first end. Two discharge ports 22 communicate with each other. The first supply port 25 communicates with the end of the hydraulic chamber 13 on the one hydraulic chamber 13a side, and the second supply port 26 communicates with the end of the hydraulic chamber 13 on the other hydraulic chamber 13b side. Yes.

  When the first discharge port 21 is closed and the hydraulic pressure is supplied from the first supply port 25 to one hydraulic chamber 13a, the hydraulic pressure is discharged from the second discharge port 22 and the eccentric sleeve 11 is rotated clockwise in FIG. Rotate. When the second discharge port 22 is closed and the hydraulic pressure is supplied from the second supply port 26 to the other hydraulic chamber 13b, the hydraulic pressure is discharged from the first discharge port 21 and the eccentric sleeve 11 rotates counterclockwise in FIG. Rotate to.

  As shown in FIG. 5, a supply switching valve 31 that switches between the first supply port 25 and the second supply port 26 is provided. Further, a discharge switching valve 32 for switching between the first discharge port 21 and the second discharge port 22 is provided. Switching of the supply switching valve 31 and the discharge switching valve 32 is controlled by a command from the control means 33. The control means 33 is input with information on the operation state (the state of operation at a low compression ratio such as at high load, the state of operation at a high compression ratio such as at low load).

  That is, according to the driving state of the vehicle, the supply switching valve 31 and the discharge switching valve 32 are controlled to be switched so that the hydraulic pressure is supplied from the first supply port 25 or the second supply port 26. It is switched that the discharge is performed from the first discharge port 21 or the second discharge port 22. That is, the rotation direction of the eccentric sleeve 11 is controlled by switching the supply switching valve 31 and the discharge switching valve 32.

  A supply path 36 from the hydraulic pump 35 is connected to the supply switching valve 31, and a discharge path 38 connected to the tank 37 is connected to the discharge switching valve 32.

  As shown in FIG. 1, the supply switching valve 31 and the discharge switching valve 32 are arranged in a valve block 41 provided in the lower block 2 of the cylinder block. The hydraulic pressure is supplied / discharged from the valve block 41 via the crank journal 4 and the crank pin 5 of the crankshaft 3.

  The state of switching between the high compression ratio and the low compression ratio will be specifically described with reference to FIGS.

  FIG. 6 shows an operation explanation for switching from a high compression ratio state to a low compression ratio state, and FIG. 7 shows an operation explanation for switching from a low compression ratio state to a high compression ratio state. (A) is the state before switching, (b) in each figure is in the middle of switching, and (c) in each figure is in the state where switching has been completed.

  As shown in FIG. 6A, in the high compression ratio state, the eccentric sleeve 11 has its rotational position fixed so that the thick portion 11a is located at the upper portion and the vane 17 is located at the right end portion in the drawing. Thus, the hydraulic pressure is filled in the other hydraulic chamber 13b. When switching to a low compression ratio is performed, the first outlet 21 is closed and the second outlet 22 is opened. In this state, the hydraulic pressure is supplied from the first supply port 25 to the one hydraulic chamber 13a.

  As shown in FIG. 6B, the hydraulic pressure in the other hydraulic chamber 13b is discharged from the second discharge port 22, and the vane 17 is pushed by the increase in the volume of the one hydraulic chamber 13a, so that the eccentric sleeve 11 is shown in FIG. Rotate around.

  As shown in FIG. 6C, the hydraulic pressure is continuously supplied from the first supply port 25 to the one hydraulic chamber 13a, whereby the hydraulic pressure in the other hydraulic chamber 13b is all discharged from the second discharge port 22, and the vane 17 Is pushed, the eccentric sleeve 11 rotates in the clockwise direction in the figure, and the thin portion 11b is positioned at the upper portion and switched to a low compression ratio state.

  Therefore, when switching from the high compression ratio state to the low compression ratio state, the actuator 12 is driven and the crankshaft 3 (see FIG. 1) is rotated (by movement of the crankpin 5 in the direction of the white arrow). ) The eccentric sleeve 11 is rotated in the direction in which the accompanying force acts.

  As a result, the eccentric sleeve 11 can be rotated with high responsiveness when switching to a low compression ratio state where responsiveness is required.

  As shown in FIG. 7 (a), in the low compression ratio state, the eccentric sleeve 11 has its rotational position fixed so that the thin-walled portion 11b is located at the top and the vane 17 is located at the left end in the drawing. Thus, the hydraulic pressure is filled in one hydraulic chamber 13a. When switching to a high compression ratio is performed, the second outlet 22 is closed and the first outlet 21 is opened. In this state, the hydraulic pressure is supplied from the second supply port 26 to the other hydraulic chamber 13b.

  As shown in FIG. 7 (b), the hydraulic pressure in one hydraulic chamber 13a is discharged from the first discharge port 21, and the vane 17 is pushed by the increase in volume of the other hydraulic chamber 13b, causing the eccentric sleeve 11 to move in the opposite direction. Rotate clockwise.

  As shown in FIG. 7C, by continuously supplying the hydraulic pressure from the second supply port 26 to the other hydraulic chamber 13b, all the hydraulic pressure in the one hydraulic chamber 13a is discharged from the first discharge port 21, and the vane 17 Is pushed, the eccentric sleeve 11 rotates counterclockwise in the figure, and the thick portion 11a is positioned at the upper portion and switched to a high compression ratio state.

  Therefore, when switching from the low compression ratio state to the high compression ratio state, high responsiveness is not required, so the actuator 12 is driven to rotate the crankshaft 3 (see FIG. 1) (white of the crankpin 5). The eccentric sleeve 11 is rotated in the opposite direction to the movement in the direction of the pulling arrow.

  In the above-described variable compression ratio device for an internal combustion engine, the eccentric sleeve 11 is rotated via the vane 17 by the actuator 12 that supplies and discharges hydraulic pressure to and from the hydraulic chamber 13. And the movement state of the piston 8 can be switched to a high compression ratio state or a low compression ratio state. For this reason, the rotational position of the eccentric sleeve 11 can be reliably controlled to a high compression ratio state or a low compression ratio state position (desired rotational position).

  In the above-described embodiment, the configuration using the actuator 12 that supplies the hydraulic pressure to the hydraulic chamber 13 and rotates the eccentric sleeve 11 via the vane 17 has been described as an example. It is also possible to use an actuator that rotates 11 or an actuator that rotates the eccentric sleeve 11 electrically.

  The present invention can be used in the industrial field of variable compression ratio devices for internal combustion engines.

2 Lower Block 3 Crankshaft 4 Crank Journal 5 Crankpin 6 Large End 7 Small End 8 Piston 10 Connecting Rod 11 Eccentric Sleeve 12 Actuator 13 Hydraulic Chamber 15 Rod Side End 16 Cap 17 Vane 21 First Discharge Port 22 Second Discharge port 25 First supply port 26 Second supply port 28 Fixed pin 29 Fitting groove 31 Supply switching valve 32 Discharge switching valve 33 Control means 35 Hydraulic pump 36 Supply path 37 Tank 38 Discharge path 41 Valve block

Claims (4)

A connecting rod in which a support hole at a small end is pivotally supported by a support shaft of a piston that reciprocates in a cylinder, and a support hole at a large end is pivotally supported by a support shaft of a crankshaft;
A rotation shaft is interposed between the support hole of the small end portion or the large end portion and the support shaft, and a center axis of the support hole of the small end portion or the large end portion is set as a center of the support shaft. An eccentric sleeve displaced with respect to the shaft;
An actuator that rotationally drives the eccentric sleeve,
The large end of the connecting rod is
A rod-side end formed on the rod-side end and forming the upper half of the support hole; and a semi-circular body that forms the lower half of the support hole and is fixed to the rod-side end. A cap,
The rod side end is provided with a fixing pin protruding and urged toward the support hole,
On the outer peripheral surface of the eccentric sleeve, a first fitting groove into which the fixing pin is fitted when being in a high compression ratio state and a second fitting into which the fixing pin is fitted when being in a low compression ratio state. A groove is provided,
The actuator has a hydraulic chamber provided across both ends in the circumferential direction at a location facing the eccentric sleeve inside the cap ,
The variable compression ratio device for an internal combustion engine , wherein the hydraulic chamber is provided only inside the cap . The variable compression ratio device for an internal combustion engine according to claim 1,
The actuator is
Transmission means for transmitting an oil pressure applied to the hydraulic chamber to the eccentric sleeve;
A variable compression ratio device for an internal combustion engine, comprising control means for controlling rotation of the eccentric sleeve by controlling hydraulic pressure applied to the hydraulic chamber. The variable compression ratio device for an internal combustion engine according to claim 2,
The eccentric sleeve is
The variable compression ratio device for an internal combustion engine, wherein the variable compression ratio device is disposed between a support hole of the large end portion of the connecting rod and a support shaft of the crankshaft. The variable compression ratio device for an internal combustion engine according to claim 3,
The hydraulic chamber is
The variable compression ratio device for an internal combustion engine, wherein the variable compression ratio device is formed in the support hole in the large end portion of the connecting rod.

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