JP2010151088A - Variable compression ratio device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress energy consumed by a drive motor (actuator). <P>SOLUTION: This device includes a variable compression ratio mechanism changing an engine compression ratio by changing a rotation position of a control shaft 18 by a drive motor 20, and a wave gear reduction gear 21 reducing speed of rotation of an input shaft of the drive motor 20 and transmitting the same to the control shaft 18 as an interrupting device changing over engagement and disengagement of power transmission between the drive motor 20 and the control shaft 18. When the engine compression ratio is changed from a high compression ratio side to a low compression ratio side, engagement and disengagement of the interrupting device is changed over according to engine operation conditions. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine provided with a variable compression ratio mechanism capable of changing an engine compression ratio.

As described in Patent Document 1, a multi-link type piston-crank mechanism is used as a variable compression ratio mechanism of a reciprocating internal combustion engine, the rotational position of the control shaft is changed by an actuator, and a part of the link configuration is moved. There is known a mechanism for changing the engine compression ratio by changing the piston top dead center position. Further, in Patent Document 1, a clutch (interruption device) that switches connection / release (interruption) of power transmission from the actuator to the control shaft is provided, and the engine compression ratio is inadvertently increased to a high compression ratio due to some problem. In the case of an abnormality such as being fixed, the connection between the actuator and the control shaft is released by a clutch, and the control shaft is automatically returned to the low compression ratio side by a combustion load or the like.
JP 2004-169660 A

  In such a variable compression ratio mechanism, it is necessary to change / hold the rotational position of the control shaft against a large combustion load or inertia load by an actuator such as an electric motor as a drive source. And increasing energy consumption are important issues. In the above-mentioned Patent Document 1, a worm reduction mechanism including a worm and a worm wheel is interposed in a power transmission path from an actuator to a control shaft. Such a worm speed reduction mechanism has a high anti-reverse action from the driven side (control shaft side) to the driving side (actuator side), that is, a high self-locking effect, but also has low transmission efficiency during driving and reduces the energy consumption of the actuator. It cannot be lowered sufficiently.

  Also, when transitioning from a high compression ratio setting state to a low compression ratio setting state, such as during sudden acceleration, if the change to the low compression ratio side by the actuator is delayed with respect to the increase in engine output, transient knocking May occur.

  The present invention relates to a variable compression ratio mechanism capable of changing an engine compression ratio by changing at least one of a top dead center position and a bottom dead center position of a piston of an internal combustion engine by changing a rotational position of a control shaft by an actuator. The present invention relates to an internal combustion engine variable compression ratio device.

  In the first aspect of the present invention, an intermittent device is provided between the actuator and the control shaft for switching connection / release of power transmission between the actuator and the control shaft, and the engine compression ratio is changed from the high compression ratio side to the low compression ratio side. In this case, the connection / release of the intermittent device is switched according to the engine operating conditions.

  In a second aspect of the invention, a wave gear reduction device is provided that decelerates the rotation of the input shaft of the actuator and transmits it to the control shaft. This wave gear reduction device is fixed to a fixed part of an internal combustion engine, and has a rigid internal gear with internal teeth formed on the inner periphery, and is arranged concentrically inside the internal gear, and has more teeth than the internal teeth. External gears formed on the outer periphery and having a flexible external gear that rotates together with the control shaft, and a wave generator disposed inside the flexible external gear. A generator rotating body that rotates together with the input shaft; and a flexible outer ring that is disposed on the outside of the generator rotating body so as to be relatively rotatable. Then, the shape of the flexible external gear via the flexible outer ring is changed to an elliptical shape in which the internal teeth and the external teeth are meshed at two locations on both sides in the major axis direction of the flexible external gear. Means for changing to a perfect circle shape close to a perfect circle is provided. The actuator and the control shaft are connected when the ellipse is formed, and the actuator and the control shaft are opened when the ellipse is formed.

  According to the present invention, by switching connection / release between the actuator and the control shaft in accordance with the engine operating conditions, it is possible to achieve both of ensuring the responsiveness of the engine compression ratio and suppressing energy consumption by the actuator. .

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

  FIG. 1 shows a variable compression ratio mechanism including a multi-link type piston-crank mechanism according to an embodiment of the present invention. As shown in the drawing, a piston 1 is slidably disposed in a cylinder 6 formed in a cylinder block 5, and one end of an upper link 11 can swing on the piston 1 via a piston pin 2. It is connected to. The other end of the upper link 11 is rotatably connected to one end portion of the lower link 13 via a first connecting pin 12. The lower link 13 is swingably attached to the crankpin 4 of the crankshaft 3 at the center thereof. The piston 1 receives combustion pressure from a combustion chamber defined above. The crankshaft 3 is rotatably supported on the cylinder block 5 by a crank bearing bracket 7.

  One end of a control link 15 is rotatably connected to the other end of the lower link 13 via a second connecting pin 14. The other end of the control link 15 is swingably supported by a fixed part of the internal combustion engine having the cylinder block 5 as a main component, and the swing fulcrum 16 serves as an internal combustion engine for changing the compression ratio. It can be displaced with respect to the main body. Specifically, a circular eccentric cam 19 is eccentrically provided on the control shaft 18 extending in parallel with the crankshaft 3, and the other end of the control link 15 is rotatable on the outer peripheral surface of the eccentric cam 19. It is mated. The control shaft 18 is rotatably supported between the crank bearing bracket 7 and the control bearing bracket 8.

  Therefore, when the rotational position of the control shaft 18 is changed to change the compression ratio, the center position of the eccentric cam 19 that becomes the swing fulcrum 16 of the control link 15 moves relative to the engine body. As a result, the movement restraint condition of the lower link 13 by the control link 15 changes, the stroke position of the piston 1 with respect to the crank angle, that is, the top dead center position and the bottom dead center position, and the engine compression ratio is changed. become.

  The rotational position of the control shaft 18 is changed and held by a drive motor 20 as a variable compression ratio actuator. A wave gear reduction device 21 is provided in the power transmission path from the drive motor 20 to the control shaft 18. As will be described later, this wave gear reduction device 21 functions as a reduction device that reduces the rotation of the input shaft of the drive motor 20 and transmits it to the control shaft 18, and transmits power between the drive motor 20 and the control shaft 18. And a function as an intermittent device (clutch) for switching between connection and release. The control unit 10 is a digital computer system that stores and executes various control processes, and according to the engine operating state, the drive motor 20 of the variable compression ratio mechanism and the hydraulic actuator of the wave gear reduction device 21, specifically, hydraulic pressure described later. A control signal is output to the solenoid 71 of the control valve 70 to control its operation.

  With reference to FIG. 2, the torque F4 generated in the control shaft 18 by the combustion load (in-cylinder pressure, combustion pressure) F1 will be described. As shown in FIG. 2 (A), the downward combustion load F1 acting on the crown surface of the piston 1 is caused by the counterclockwise torque shown in the figure around the crank pin 4 to the lower link 13 via the upper link 11. Acts as F2. Since the control link 15 is connected to the end of the lower link 13 that is not connected to the upper link 11 with respect to the crank pin 4, the control link 15 is controlled by the torque F <b> 2 acting on the lower link 13. A diagonally upward load F3 is applied along the axial direction. The end of the control link 15 that is not connected to the lower link 13 is pivotally supported by an eccentric cam 19 (FIG. 1) of the control shaft 18. The center position of the eccentric cam, that is, the control link 18 is supported. The swing fulcrum 16 is eccentric by a predetermined amount compared to the rotation center (main bearing portion) 18A of the control shaft 18.

  FIG. 2B shows the positional relationship between the control shaft center 18 </ b> A and the swing fulcrum 16. As shown in the drawing, since the load F3 resulting from the combustion load F1 acts on the eccentric cam of the control shaft 18 at each compression ratio obliquely above the engine, the torque F4 is applied to the control shaft 18 on the high compression ratio side ( It acts in the direction from the highest compression ratio to the lower compression ratio (minimum compression ratio). Therefore, when the torque F4 is changed from the high compression ratio side to the low compression ratio side, it acts as an assist torque in the same direction as the change direction, and when the torque F4 is changed from the low compression ratio side to the high compression ratio side, It acts as a torque in the direction opposite to the change direction.

  The wave gear reduction device 21 will be described with reference to FIGS. The wave gear reduction device 21 is fixed to a fixed part such as a cylinder block 5 or a casing of an internal combustion engine, and has a rigid internal gear 22 having an inner tooth (spline) 23 formed on the inner periphery thereof, and an inner side of the internal gear 22. The external teeth (splines) 25 that are arranged concentrically with each other and have two fewer teeth than the internal teeth 23 are formed on the outer periphery, and the flexible external gear 24 that rotates together with the control shaft 18. And a wave generator 26 disposed inside the external gear 24.

  The internal gear 22 has an annular shape, and a number of bolt holes 27 into which fixing bolts for fixing to a fixing portion of the internal combustion engine are fitted are intermittently formed in the circumferential direction. In order not to be deformed in this way, it is made of a metal material harder than the flexible external gear 24. The flexible external gear 24 has a thin bottomed cylindrical shape composed of a disk-shaped bottom portion 28 and a cylindrical portion 29, and the shape of the cylindrical portion 29 can be bent and deformed into an elliptical shape or a perfect circular shape as shown in FIG. It has become a thing. The “perfect circle shape” is a shape closer to a perfect circle than that of the elliptic shape, that is, a shape having a low ellipticity, and does not mean a complete perfect circle. The flexible external gear 24 is concentrically connected to the flange 31 of the control shaft 18 by a fixing bolt 30 (see FIGS. 3 and 4) while the bottom 28 is fitted to the convex portion 29 at one end of the control shaft 18. Fixed.

  The wave generator 26 is mainly composed of a generator rotator 33 (see FIG. 6) fixed to the input shaft 32 of the drive motor 20 and rotating together with the input shaft 32. A ball bearing 34 that can be bent and deformed in the radial direction is concentrically attached to the outside of the generator rotor 33. The inner ring inside the ball bearing 34 is attached to the outer periphery of the generator rotator 33 (slider housing 41 described later), and the outer ring arranged outside is flexible so as to be rotatable relative to the generator rotator 33. An outer ring 35 is configured.

  Since the control shaft 18 and the generator rotator 33 cause a rotation difference corresponding to the reduction ratio, the generator rotator 33 (the slider housing 41) that rotates relative to each other is disposed between the end surface of the generator rotator 33 and the end surface of the control shaft 18. A sliding member 36 is provided. The sliding member 36 is, for example, a plate-like copper alloy bushing in which an oil-containing material is integrated as shown in the figure, or a thrust bearing using a ball.

  As shown in FIG. 6, the generator rotator 33 includes a disk-shaped slider housing 41, a pair of sliders 42 fitted to the slider housing 41 so as to be slidable in the radial direction, and the input shaft 32 of the drive motor 20. And a connection member 43 that is connected to and fixed to the input shaft 32 and rotates integrally with the input shaft 32. The connecting member 43 and the slider housing 41 are fastened together by four fixing bolts 44 (see FIGS. 3 and 4). On the outer periphery of the slider housing 41, slider grooves 45 are formed at two locations on both sides in the diametrical direction. A hydraulic chamber 46 is defined between the slider groove 45 and the back surface of the slider 42, and the operation of the slider 42 is controlled according to the hydraulic pressure supplied to the hydraulic chamber 46. The front end surface and the back surface of the slider 42 are curved according to the curved shape of the slider housing 41.

  As shown in FIG. 5A, when the slider 42 protrudes from the outer periphery of the slider housing 41, the flexible external gear 24 is elliptically shaped by the slider 42 via the bearing 34 including the flexible outer ring 35. It becomes. In this elliptical state, the flexible external gear 24 is locally pressed to the internal gear 22 side, and the internal teeth 23 and the external teeth 25 are engaged at two locations in the diameter direction. As a result, the meshing position of the inner teeth 23 and the outer teeth 25 moves in the circumferential direction with the rotation of the generator rotator 33, and when the generator rotator 33 makes one rotation, the flexible external gear 24 moves to the teeth. Moves in the rotational direction by two sheets of difference. That is, in this elliptical state, power is transmitted with a large reduction ratio from the input shaft 32 of the drive motor 21 to the control shaft 18 while power transmission between the input shaft 32 and the control shaft 18 is connected. .

  On the other hand, as shown in FIG. 5B, the slider 42 is pulled into the slider housing 41, more specifically, the tip surface forming the cylindrical surface of the slider 42 does not protrude from the outer peripheral surface of the slider housing 41. In the retracted state retracted to the inside of the slider groove 45, the ball bearing 34 and the flexible external gear 24 are not pressed against the internal gear 22 side. Therefore, the flexible external gear 24 is more round than the elliptical shape described above. It becomes a perfect circle shape close to. Accordingly, the meshing position of the inner teeth 23 and the outer teeth 25 does not move in the circumferential direction as the generator rotating body 33 rotates, and the generator rotating body 33 and the flexible external gear 24 are They are idled with each other via 34. For this reason, in the state of this perfect circle shape, the power transmission between the input shaft 32 of the drive motor 20 and the control shaft 18 is cut off.

  Thus, by changing the radial position of the slider 42 by hydraulic pressure, the ellipticity of the wave generator 26 can be changed, and the hydraulic mechanism using the slider 42 is connected to the drive motor 20 and the control shaft 18. It functions as an interrupting device that interrupts power transmission.

  Next, the oil supply path 60 and the like to the hydraulic chamber 46 will be described with reference to FIGS. 4, 6 and 7. As shown in FIG. 7, the engine oil stored in the oil pan 51 is pumped to the main gallery 53 by an oil pump 52 and supplied as hydraulic oil to various hydraulic actuators, and lubricated parts such as a crankshaft and a cylinder head. In order to lubricate the bearing portion of the control shaft 18, a part thereof is supplied to the axial oil passage 61 (see FIG. 4) of the control shaft 18. The oil passage from the oil pump 52 to the main gallery 53 has a check valve 54 that prevents backflow, an oil filter 55 that removes foreign matter in the oil, a pressure sensor 56 that detects supply pressure, and engine oil that is discharged. A relief valve 57 and the like for releasing to the passage side are provided.

  As shown in FIGS. 4 and 6, the engine oil supplied to the axial oil passage 61 of the control shaft 18 is formed in the oil supply passage 60, more specifically, in the sliding member 36 and the connection member 43. The axial oil passages 62, 63, the radial oil passage 64 and the outer circumferential groove 65 formed on the convex portion of the connecting member 43 fitted in the center hole of the slider housing 41, and the bottom surface of the slider groove 45 of the slider housing 41 The oil is supplied to the hydraulic chamber 46 through an oil hole 66 penetrating through the oil hole 66.

  Further, an oil discharge path 68 for discharging (draining) engine oil in the hydraulic chamber 46 is formed using the inside of the connection member 43 and the like in the same manner as the oil supply path 60. A hydraulic control valve 70 is provided as an electromagnetic valve. By controlling energization to the solenoid 71 of the hydraulic control valve 70, the spool 72 moves against the spring force of the coil spring 73, and the oil discharge path 68 is opened and closed.

  In this embodiment, when the solenoid 71 is energized and the spool 72 is moved to the left in FIG. 7 against the spring force of the coil spring 73, the oil discharge path 68 is closed and the hydraulic pressure in the hydraulic chamber 46 is increased. As a result, the slider 42 protrudes in the radial direction from the slider housing 41, and the elliptical shape shown in FIG. On the other hand, when the energization of the solenoid 71 is stopped, the spool 72 moves to the right in FIG. 7 by the spring force of the coil spring 73, the oil discharge path 68 is opened, and the engine oil in the hydraulic chamber 46 is discharged. The hydraulic pressure is lowered, and the slider 42 is retracted in the slider housing 41, so that a perfect circle shape shown in FIG. 5B, that is, the intermittent device is opened. In this embodiment, when the energization of the solenoid 71 of the hydraulic control valve 70 is in an initial state, the engine oil is discharged and the interrupting device is opened. In other words, the interrupting device may be in a connected state in an initial state where power is cut off.

  Referring to FIG. 7, the respective angular positions of control shaft 18 and input shaft 32 of drive motor 20 are detected by detection devices 75 and 76 such as an angle detection sensor. Each time the connection between the control shaft 18 and the input shaft 32 of the drive motor 20 is released by the interrupting device with respect to the initial operation state, a deviation occurs in the mutual angular position, but the current position of the engine compression ratio is controlled The angle of the shaft 18 may be set as an angle, and when the interrupting device is connected from the open state, the input shaft 32 can continue the feedback control with the control axis angle as an angle. Such control is stored and executed by the control unit 10.

  FIG. 8 shows an example of setting the engine compression ratio according to the engine operating conditions. Region (D) shows a mode operation region of low rotation and load using a high compression ratio setting, and regions (A) to (C) are more than the mode operation region (D) using a setting of low compression. The operating range on the high rotation / high load side is shown.

  FIG. 9 is a flowchart showing the control flow of this embodiment. In step S11, the operation range using the setting of the low compression ratio (low ε) from the mode operation range (D) on the low rotation low load side, which is the engine operation range using the setting of the high compression ratio (high ε), that is, the mode described above. It is determined whether or not it is a transition period of switching from the operating range (D) to the operating range (A) to (C) on the high rotation side / high load side.

  In the transition period from the mode operating range (D) using the high compression ratio setting to the operating range (A) to (C) using the low compression ratio setting, the process proceeds to step S12, and high responsiveness is required. It is determined whether or not it is a transition period to shift to the operating region (A) on the low rotation / high load side. In the operating region (A) on the low rotation / high load side, there is a high risk of abnormal combustion such as knocking. Therefore, in this case, since it is necessary to quickly control the engine compression ratio to be low, driving to the low compression ratio side of the compression ratio by the drive motor 20 as a drive source, and assist torque F4 resulting from the in-cylinder pressure F1. Using both of them (see FIG. 2), the operation in the low compression ratio direction is performed. Specifically, the process proceeds to step S16, energizing the solenoid 71 to bring the slider 42 into the protruding state, the flexible external gear 24 to be elliptical, and the intermittent device to the connected state, that is, from the input shaft 32 of the drive motor 21. After the power is transmitted to the control shaft 18 while decelerating, the drive motor 20 drives the control shaft 18 to the low compression ratio side (step S17). As a result, the control shaft 18 is driven to a low target compression ratio by utilizing both the operation of the drive motor 20 toward the low compression ratio and the assist torque F4 (see FIG. 2) caused by the in-cylinder pressure F1. It is possible to act quickly in the compression ratio direction and reduce the occurrence frequency of knocking.

  On the other hand, in the transition period from the mode operating range (D) using the high compression ratio setting to the operating range (A) to (C) using the low compression ratio setting, the high load side region (A) In the transition period when shifting to the regions (B) and (C) on the higher rotation side, the occurrence frequency of the above-mentioned knocking is relatively low, so that the responsiveness is higher as in the transition period to the region (A). Is not required. Therefore, in such a transitional period from the mode operation region (D) to the regions (B) and (C), the process proceeds from step S12 to steps S13 and S14, the disconnection device is disconnected, and the drive motor 20 is turned off. Without using, the compression ratio is changed in the low compression ratio direction only by the assist torque F4 (see FIG. 2) in the low compression ratio direction by the in-cylinder pressure F1. Specifically, the solenoid 71 of the hydraulic control valve 70 is de-energized to release the hydraulic pressure, the slider 42 is in a retracted state, the flexible external gear 24 is in a perfect circle shape, and the intermittent device is in a perfect circle state. After the power transmission from the input shaft 32 of the drive motor 21 to the control shaft 18 is interrupted, the operation of the drive motor 21 is stopped, that is, the energization is stopped. Thereby, it is not necessary to use any energy consumption, that is, power consumption of the drive motor 21, and the power consumption of the motor can be reduced. In this case, the control shaft 18 moves in the low compression ratio direction by the assist torque F4 in the low compression ratio direction caused by the combustion load.

  If the interrupting device is opened in step S13, the angular position of the control shaft 18 may fluctuate. Since this is not desirable when the compression ratio position is detected, when the predetermined target compression ratio is reached in step S15, the process proceeds to step S16 to connect the intermittent device, and from the drive motor 21 to the control shaft 18. The drive shaft 21 is driven toward the target compression ratio in step S17 after the power transmission path is connected and fixed, so that the control shaft 18 can be favorably held at the rotational position corresponding to the target compression ratio. Thus, accurate variable compression ratio control can be performed.

  FIG. 8 shows an example in which the high compression ratio is set only in the mode operation region (D) that is used most frequently. However, this is only an example, and switching by the intermittent device as appropriate in other settings. By performing the control, the energy consumption of the drive motor 20 can be reduced.

  Step S18 is a transitional period from the engine operating range (A) to (C) using the low compression ratio (low ε) setting to the engine operating range (D) using the high compression ratio (high ε) setting. Determine whether.

  In the transition period from the low ε to the high ε, in step S19, the intermittent device is temporarily opened, that is, the hydraulic pressure is released by the hydraulic control valve 70 to place the slider 42 in the retracted state. After the power transmission between the drive motor 21 and the control shaft 18 is cut off with a round shape 24, the drive motor 21 is started toward the target high compression ratio in step S20.

  In step S <b> 21, it is determined whether a predetermined delay has elapsed after the drive motor 21 is activated. For example, it is determined whether a certain delay time (for example, several seconds) has elapsed since the start or whether the input shaft 32 of the drive motor 21 has reached a predetermined rotational angular velocity. If it is determined that a predetermined delay has elapsed from the start, the process proceeds from step S21 to step S22, and the interrupting device is connected. That is, the hydraulic pressure is supplied from the hydraulic control valve 70 to bring the slider 42 into a protruding state, and the flexible external gear 24 is formed in an elliptical shape to connect power transmission between the drive motor 21 and the control shaft 18.

  When the drive motor 21 is activated, the generator rotator 33 of the wave generator 26 starts rotating from the stopped state. If the generator rotator 33 starts rotating and the slider 42 is projected to make the flexible external gear 24 have an elliptical shape, the starting torque of the drive motor 21 becomes very large and the power consumption increases. On the other hand, in this embodiment, when the drive motor 21 is started, the intermittent device is opened (step S19). Specifically, the slider 42 is set in the retracted state, and the input shaft 32 and the generator rotor 36 are flexible. Since the external gear 24 and the control shaft 18 are idling, the resistance when the drive motor 20 is activated, that is, the motor electromotive force can be greatly reduced. As described above, the intermittent device is connected after a predetermined delay from the start of the motor. Specifically, the slider 42 is protruded to change the flexible external gear 24 into an elliptical shape. Since the inertial load accompanying the rotation of the rotating body 33 can be used for the deformation of the flexible external gear 24 into an elliptical shape, the elliptical shape can be favorably changed.

  In particular, when the electric motor 21 is used as a drive source of the variable compression ratio mechanism as in the present embodiment, the operation of the electric motor 21 has a large influence on the magnitude of power consumption during the activation. Power consumption can be greatly reduced.

  However, when the flexible external gear 24 is changed to an elliptical shape after a predetermined delay from the start of the drive motor 21 (that is, when an intermittent device is connected), the flexibility is simply set at the same time as the drive motor 21 is started. Compared with the case where the gear 24 is deformed into an elliptical shape, the time until the control shaft 18 is rotationally driven is increased by the delay. Therefore, if such a delay process is performed during the transitional transition period from the high compression ratio side to the low compression ratio side, the reduction of the compression ratio may be delayed and knocking may occur.

  Here, as shown in FIG. 2, because the torque F4 acting on the control shaft 18 due to the in-cylinder pressure F1 is in the low compression ratio direction, during the transitional transition period from the low compression ratio side to the high compression ratio side. It is necessary to overcome the torque F4 and drive the control shaft 18 in the high compression ratio direction, and the load and power consumption of the drive motor 21 are very large. The operating condition in which the low compression ratio side is switched to the high compression ratio side is when the throttle is at a constant opening or OFF, for example, when the accelerator pedal is returned during high-speed operation, and abnormal combustion such as knocking occurs. It is unlikely to occur. That is, in such a transition period from the low compression ratio side to the high compression ratio side, high responsiveness to knocking is not required, but rather an increase in power consumption at the time of starting the drive motor 21 becomes a problem. Therefore, in the present embodiment, the delay control of steps S19 to S22 as described above is performed in the transitional transition period from the low compression ratio side to the high compression ratio side, and thus the drive motor 21 is controlled. The power consumption at the start-up can be greatly reduced.

  Further, according to the present embodiment, the connection between the drive motor 21 and the control shaft 18 is separated by the interrupting device, so that, for example, under a driving condition where operation at a low compression ratio is desirable, the high compression ratio is fixed due to some problem. In such a failure state, by continuing the engine operation in a state where the connection of the intermittent device is cut off, the assist torque F4 resulting from the combustion load F1 is used to automatically move in the low compression ratio direction. It is also possible to change the compression ratio.

  When an electromagnetic clutch as shown in FIG. 10 to be described later is used as the interrupting device, it is inevitable to increase the diameter of the clutch portion directly connected to the control shaft 18 on which the highly variable torque acts, but there are large restrictions on the layout. According to the interrupting device using the wave gear reduction device described above, the connection state can be switched by changing the position of the slider 42 provided in the wave generator 26, which affects the magnitude of the torque acting on the control shaft 18. Therefore, the size and weight can be reduced.

  Further, since the slider 42 is driven by the hydraulic pressure of the engine oil, it is possible to easily and easily obtain a large thrust force against the reaction force when the flexible external gear 24 is deformed into an elliptical shape. It is. In addition, by adopting a hydraulic drive type, the lubricating effect on the sliding portions of the generator rotor 33 and the slider 42 is also used, and a simple and compact configuration can be achieved.

  As described above, the present invention has been described based on one embodiment. However, the present invention is not limited to the above embodiment, and includes various modifications and changes without departing from the spirit of the present invention. For example, FIG. 10 shows a reduction gear and an interrupting device according to another embodiment of the present invention. In this embodiment, the speed reducer includes a worm gear 80 including a worm 81 provided on the input shaft 32 of the drive motor 21 and a worm wheel 82 attached to the control shaft 18. The interrupting device is configured as an electromagnetic clutch 83 having a worm wheel side clutch plate 84 and a control shaft side clutch portion 85 for electromagnetically adsorbing the clutch plate 84.

FIG. 3 is a cross-sectional view illustrating a variable compression ratio mechanism according to an embodiment of the present invention. Explanatory drawing which shows the torque which acts on a control axis | shaft resulting from a combustion load. The disassembled perspective view which shows the wave gear reducer which concerns on a present Example. Sectional drawing which follows the AA line of FIG. 3 in the assembly state of the said wave gear reducer. The perspective view which shows the state of (A) being elliptical shape and (B) being perfect circle shape. The disassembled perspective view which shows a generator rotary body. Explanatory drawing which shows the hydraulic system of a hydraulic chamber. Explanatory drawing which shows the setting of the engine compression ratio according to engine operating conditions. The flowchart which shows the flow of control of a present Example. The perspective view which shows the reduction gear device and interrupting device which concern on the other Example of this invention.

Explanation of symbols

1 ... Piston 18 ... Control shaft 20 ... Drive motor (actuator)
21 ... Wave gear reduction device (intermittent device)
22 ... Internal gear 24 ... Flexible external gear 25 ... External gear 26 ... Wave generator 35 ... Flexible outer ring 42 ... Slider

Claims (9)

A variable compression ratio mechanism capable of changing an engine compression ratio by changing at least one of a top dead center position and a bottom dead center position of a piston of an internal combustion engine by changing a rotational position of a control shaft by an actuator;
An intermittent device provided between the actuator and the control shaft and switching connection / release of power transmission between the two,
A variable compression ratio device for an internal combustion engine, wherein when the engine compression ratio is changed from a high compression ratio side to a low compression ratio side, connection / release of the intermittent device is switched according to engine operating conditions.   In the case of changing from the high compression ratio side to the low compression ratio side, and in predetermined operating conditions that require operation in the direction of the low compression ratio with high response, the intermittent device is in a connected state, and When the control shaft is driven by the actuator to the low compression ratio side and the change is made from the high compression ratio side to the low compression ratio side except for the predetermined operating conditions that require operation in the high compression low compression ratio direction, the intermittent device is 2. The variable compression ratio device for an internal combustion engine according to claim 1, wherein the variable compression ratio device is in an open state.   In the transition period of change of a predetermined engine compression ratio, the intermittent device is opened when the actuator is activated, and the intermittent device is connected after a predetermined delay from the activation of the actuator. The variable compression ratio device for an internal combustion engine according to claim 1 or 2.   4. The variable compression ratio device for an internal combustion engine according to claim 3, wherein the change transition period of the predetermined engine compression ratio is a case where the engine compression ratio is changed from the low compression ratio side to the high compression ratio side. Means for detecting the angular position of the control shaft;
Means for detecting the angular position of the input shaft of the actuator,
5. The variable internal combustion engine according to claim 1, wherein the actuator is controlled based on an angular position of the control shaft when the intermittent device is switched from an open state to a connected state. 6. Compression ratio device. A wave gear reduction device for reducing the rotation of the input shaft of the actuator and transmitting it to the control shaft;
This wave gear reduction device
A rigid internal gear fixed to a fixed part of the internal combustion engine and having internal teeth formed on the inner periphery;
A flexible external gear that is concentrically disposed on the inner side of the internal gear, has external teeth having a smaller number of teeth than the internal teeth, and rotates together with the control shaft;
A wave generator disposed inside the flexible external gear,
The wave generator includes a generator rotating body that rotates together with the input shaft,
A flexible outer ring disposed on the outside of the generator rotor so as to be relatively rotatable,
The interrupting device has a shape of the flexible external gear via the flexible outer ring, an elliptical shape in which the internal teeth and the external teeth are engaged at two positions on both sides in the major axis direction of the flexible external gear, and the elliptical shape. The shape is changed to a perfect circle shape that is closer to a perfect circle than the shape, and is connected when the ellipse is formed, and is opened when the ellipse is formed. A variable compression ratio device for an internal combustion engine according to any one of the above. A variable compression ratio mechanism capable of changing an engine compression ratio by changing at least one of a top dead center position and a bottom dead center position of a piston of an internal combustion engine by changing a rotational position of a control shaft by an actuator;
A wave gear reducer that decelerates the rotation of the input shaft of the actuator and transmits it to the control shaft,
This wave gear reduction device
A rigid internal gear fixed to a fixed part of the internal combustion engine and having internal teeth formed on the inner periphery;
A flexible external gear that is concentrically disposed on the inner side of the internal gear, has external teeth having a smaller number of teeth than the internal teeth, and rotates together with the control shaft;
A wave generator disposed inside the flexible external gear, the wave generator being rotatable relative to the generator rotating body rotating with the input shaft and outside the generator rotating body. A flexible outer ring disposed on
In addition, the shape of the flexible external gear via the flexible outer ring is changed to an elliptical shape in which the inner teeth and the outer teeth are engaged at two locations on both sides in the major axis direction of the flexible outer gear. It has a means to change to a perfect circle shape close to a perfect circle,
A variable compression ratio apparatus for an internal combustion engine, wherein the actuator and the control shaft are connected when the ellipse is formed, and the connection between the actuator and the control shaft is released when the ellipse is formed. A slider attached to the generator rotor so as to be movable in the radial direction;
When the slider is in a protruding state in which the slider is protruded from the generator rotating body, the flexible external gear becomes the elliptical shape via the flexible outer ring,
8. The variable compression ratio device for an internal combustion engine according to claim 6, wherein the flexible external gear has the perfect circular shape when the slider is retracted into the generator rotor. .   9. The variable compression ratio device for an internal combustion engine according to claim 6, wherein the slider is operated by hydraulic pressure of engine oil.

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