JP2009062926A - Variable compression ratio internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple auxiliary driving source for transferring the compression ratio to the compression ratio capable of performing a stable operation, when the driving source of a variable compression ratio mechanism causes failure, in a variable compression ratio internal combustion engine. <P>SOLUTION: A spring or the spring and a linear solenoid connected to the spring in series are installed in a driving force transmission mechanism of the variable compression ratio mechanism. The spring is energized by driving force of the driving source. When the driving source causes failure, the driving force transmission mechanism is driven by energizing force of the spring and the driving force of the linear solenoid, and the variable compression ratio mechanism is transferred to the predetermined compression ratio. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

  In a variable compression ratio internal combustion engine that changes the compression ratio according to the operating state, various proposals have been made regarding auxiliary mechanisms and control devices for controlling the compression ratio according to the operating state.

  Patent Document 1 discloses an auxiliary mechanism that contributes to simplification of control and miniaturization of a variable compression ratio mechanism by reducing drive torque when changing the compression ratio of a variable compression ratio internal combustion engine. In Patent Document 2, it is possible to improve the quickness when shifting the compression ratio of a variable compression ratio internal combustion engine from a high compression ratio to a low compression ratio and effectively avoid the occurrence of a high load / high compression ratio situation. An auxiliary mechanism that can be used is shown.

JP 2004-324464 A JP 2004-150353 A Japanese Patent Laid-Open No. 2005-16381

  However, in the variable compression ratio mechanisms of Patent Document 1 and Patent Document 2, when the drive source that variably controls the compression ratio fails, the compression ratio at the time of the failure is maintained, so the failure occurred at a high compression ratio. In some cases, a high load / high compression ratio may occur.

  That is, in the variable compression ratio mechanisms of Patent Document 1 and Patent Document 2, the driving force transmission mechanism that makes the compression ratio variable transmits the rotation of the worm to the worm wheel, and the rotation of the worm wheel changes the compression ratio. Drive the shaft. The worm is driven by a motor attached to the shaft end of the drive shaft. Since the worm cannot be moved from the worm wheel side due to the meshing characteristics of the worm / worm wheel mechanism, the worm is not moved by the operation of the internal combustion engine. Therefore, when the motor fails, the compression ratio is maintained at the current compression ratio.

  Because of such characteristics, if a high load operation is performed when the motor fails while being controlled to a high compression ratio, a high compression ratio / high load state may occur and knocking may occur. Therefore, it is preferable to shift to the low compression ratio side when the motor fails.

  On the other hand, if the variable compression ratio mechanism is set to the lowest compression ratio, the compression pressure or the in-cylinder temperature may be insufficient at the time of low temperature start, which may make it difficult to start. Patent Document 3 discloses a start control device that calculates a target compression ratio for starting and controls the variable compression ratio mechanism so as to be the target compression ratio for starting. If the ratio shift position is a constant compression ratio that can ensure the required compression ratio even at low temperature start, or can be controlled to the target compression ratio for start, the same effect can be achieved. This is advantageous because a separate start control device is not required.

  It is an object of the present invention to provide a simple auxiliary drive source that shifts the compression ratio to a compression ratio that allows stable operation when the drive source of the variable compression ratio mechanism fails in a variable compression ratio internal combustion engine. Yes.

  According to the first aspect of the present invention, there is provided a variable compression ratio internal combustion engine, a variable compression ratio mechanism capable of changing the combustion chamber volume, and a drive source for generating a drive force for changing the compression ratio. And an auxiliary drive source capable of shifting the variable compression ratio mechanism to a predetermined compression ratio when the drive source fails. Is provided separately from the drive source.

  That is, according to the first aspect of the present invention, when the drive source that drives the variable compression ratio mechanism fails, the auxiliary drive source acts to shift the compression ratio to a predetermined compression ratio that enables stable operation.

  According to the second aspect of the present invention, the auxiliary drive source is a spring attached to the drive force transmission mechanism, and when this spring is biased by the drive force of the drive source and the drive source fails, The variable compression ratio internal combustion engine according to claim 1, wherein the spring drives the driving force transmission mechanism.

  That is, in the invention of claim 2, when a motor that is a drive source of the variable compression ratio mechanism fails, the force of the biased spring acts and a predetermined compression ratio that enables stable operation of the compression ratio. To transition. The spring is set so that the biasing force becomes zero at a predetermined compression ratio, and when the drive source is operating normally, the spring is attached so as to apply the biasing force by rotating the drive source. .

  According to the invention described in claim 3, the auxiliary drive source is a spring attached to the drive force transmission mechanism and a linear solenoid connected in series to the spring, and this spring is biased by the drive force of the drive source. The variable compression ratio internal combustion engine according to claim 1, wherein when the drive source fails, a spring and a linear solenoid connected in series to the spring drive the drive force transmission mechanism.

  That is, in the invention of claim 3, when a motor that is a drive source of the variable compression ratio mechanism fails, the force of the biased spring acts and a predetermined compression ratio that enables stable operation of the compression ratio. To transition. The spring is connected in series to a solenoid having a linear motion movable part (referred to herein as a “linear solenoid”), and the linear solenoid is fixed to a fixed point in the crankcase. The spring is set so that the biasing force becomes zero at a predetermined compression ratio, and when the drive source is operating normally, the spring is attached so as to apply the biasing force by rotating the drive source. . In addition, the driving force of the linear solenoid is added to the biasing force of the spring by expanding and contracting the moving length of the linear solenoid movable portion of the linear solenoid (referred to as “the operating length of the linear solenoid” in this specification). Thus, it is possible to give a range to the compression ratio that is shifted when the drive source fails. Since the range of expansion and contraction of the operating length of the linear solenoid is limited, the control range of the compression ratio is limited, but optimization control in a relatively narrow range can be performed by controlling the linear solenoid by the ECU. it can.

  According to the fourth aspect of the present invention, there is provided the variable compression ratio internal combustion engine according to the second or third aspect, wherein the predetermined compression ratio is a compression ratio that provides the lowest compression ratio.

  That is, in the invention of claim 4, when the drive source that drives the variable compression ratio mechanism fails, the force of the biased spring acts to shift the compression ratio to the position where the compression ratio becomes the lowest. Driving without knocking can be performed.

  According to the fifth aspect of the present invention, there is provided the variable compression ratio internal combustion engine according to the second or third aspect, wherein the predetermined compression ratio is a preset compression ratio.

  That is, in the invention of claim 5, when the drive source that drives the variable compression ratio mechanism fails, the force of the biased spring acts to shift the compression ratio to a predetermined set compression ratio, thereby stabilizing You can drive. This set compression ratio can be arbitrarily determined in advance.For example, if the compression ratio is such that knocking does not occur and a certain compression ratio can be ensured even at low temperature start, It is advantageous in that it is possible to avoid a difficulty in starting due to insufficient compression pressure or in-cylinder temperature at the time of starting.

  According to the sixth aspect of the present invention, the predetermined compression ratio can be arbitrarily changed within a predetermined compression ratio range by adjusting the operating length of the linear solenoid. A variable compression ratio internal combustion engine as described is provided.

  That is, in the invention of claim 6, by adding the driving force of the linear solenoid to the urging force of the spring, it is possible to give a range to the compression ratio that shifts when the driving source fails. The expansion / contraction range of the operating length of the linear solenoid is limited, so the control range of the compression ratio is limited, but by controlling the linear solenoid by the ECU, for example, the optimum suitable for the temperature of the internal combustion engine at the start A relatively narrow range of optimization control can be performed so as to obtain a starting compression ratio.

  According to the seventh aspect of the present invention, there is provided a variable compression ratio internal combustion engine having a variable valve timing mechanism, wherein the variable compression ratio mechanism can change the combustion chamber volume, and the driving force for changing the compression ratio. And a driving force transmission mechanism that transmits the driving force of the driving source to the variable compression ratio mechanism. Further, when the driving source fails, the variable compression ratio mechanism is shifted to a predetermined compression ratio. An auxiliary drive source that can be provided separately from the drive source, the auxiliary drive source is a spring attached to the drive force transmission mechanism and a linear solenoid connected in series with the spring, and the spring is driven by the drive force of the drive source. When energized and the variable valve timing mechanism fails, the operating length of the linear solenoid moves to a position where no drive force is applied to the spring so that the variable compression ratio internal combustion engine is operated at the low compression ratio side. When the drive source fails, a predetermined compression ratio is determined in advance by adjusting the spring and the linear solenoid connected in series with the spring to drive the driving force transmission mechanism and adjust the operating length of the linear solenoid. A variable compression ratio internal combustion engine that can be arbitrarily changed within a range of the compression ratio is provided.

  That is, in the invention of claim 7, when the variable valve timing (VVT) mechanism fails, it is preferable to operate on the low compression ratio side. Therefore, in the case of the present invention having the linear solenoid, the variable compression is performed. In order to control the internal combustion engine on the low compression ratio side, the variable compression ratio (VCR) control operation can be performed after the operating length of the linear solenoid is shifted to the low compression ratio operation side. When the drive source that drives the mechanism breaks down, the range of the compression ratio to which the biased spring force acts can be shifted, and the linear solenoid is controlled by the ECU, for example, at the time of starting. A relatively narrow range of optimization control can be performed so as to obtain an optimum starting compression ratio suitable for the temperature of the internal combustion engine.

  According to the invention described in each claim, in a variable compression ratio internal combustion engine, when the drive source of the variable compression ratio mechanism fails, a simple auxiliary drive source that shifts the compression ratio to a compression ratio that allows stable operation. The common effect of providing

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

  FIG. 1 is a diagram for explaining a schematic configuration of an embodiment when the present invention is applied to a variable compression ratio internal combustion engine 10. The chamber volume is changed and the compression ratio is changed. The driving force for this is obtained by the motor 16 that drives the drive shaft 15. Torque generated by the motor 16 is transmitted from the worms 11 and 13 to the worm wheels 12 and 14, and the cam shafts (34 and 35 in FIG. 3) provided with eccentric cams are rotated to move the cylinder block 2 in the vertical direction. . A torsion coil spring 17 is attached to the shaft end of the drive shaft 15 opposite to the motor 16, and the motor 16 compresses the drive shaft 15 while urging the torsion coil spring 17 by driving the drive shaft 15. The cylinder block 2 is moved so that the ratio is, for example, a high compression ratio. When the motor stops, the urging force of the torsion coil spring 17 acts as an auxiliary drive source by rotationally driving the drive shaft 15 in the direction opposite to the drive rotation direction of the motor, and the cylinder block 2 is reduced in compression. It moves to the specific side, and stops at the position where the urging force of the torsion coil spring 17 becomes zero, that is, the initially set compression ratio position.

  FIG. 2 is a view of the torsion coil spring 17 as viewed from the direction A in FIG. 1. One end of the torsion coil spring 17 is fixed to a fixing portion 18 provided in the crankcase 1, and the other end Is fixed on the shaft circumference of the shaft end of the drive shaft 15. In FIG. 2, when the drive shaft 15 is rotated in the clockwise direction by the drive motor, the torsion coil spring 17 is wound in the clockwise direction, and an urging force for driving the drive shaft 15 in the counterclockwise direction is applied.

  FIG. 3 is an exploded perspective view of the variable compression ratio internal combustion engine 10 to which the present invention is applied. As described in FIG. 1, the torque generated by the motor 16 is transmitted from the worms 11 and 13 to the worm wheels 12 and 14, and the camshafts 34 and 35 having eccentric cams are rotated to move the cylinder block 2 in the vertical direction. Move.

  FIG. 4 is a graph showing the relationship between the urging force of the torsion coil spring 17 and the compression ratio. In this figure, when the motor driving torque increases, the urging force applied to the torsion coil spring 17 increases and the compression ratio increases. Move to the compression ratio side. When the cylinder block 2 is moved to the high compression ratio side by attaching the motor 16 so that the urging force of the torsion coil spring 17 becomes zero at the position where the compression ratio becomes the lowest compression ratio at the time of initial setting, the twist The coil spring 17 has a biasing force toward the low compression ratio side, and the biasing force is maximized at a position where the compression ratio is the highest. Therefore, after the motor 16 breaks down and the power supply is cut off, the urging force of the torsion coil spring 17 acts as an auxiliary drive source, rotates the drive shaft 15 in the reverse direction, and moves the cylinder block 2 to the low compression ratio side. The cylinder block 2 stops moving at a position where the urging force of the torsion coil spring 17 becomes zero, that is, a position where the compression ratio is the lowest.

  FIG. 5 is also a graph showing the relationship between the urging force of the torsion coil spring 17 and the compression ratio. The mounting position at which the urging force of the torsion coil spring 17 described with reference to FIG. 4 is different from FIG. 4 in that it is a position that is a predetermined compression ratio between the low compression ratio and the high compression ratio (this position is referred to as “set compression ratio” in this specification). Yes. That is, after the motor 16 breaks down and the power supply is cut off, the urging force of the torsion coil spring 17 acts as an auxiliary drive source, rotates the drive shaft 15 in the reverse direction, and moves the cylinder block 2 to the low compression ratio side. The cylinder block 2 stops moving at a position where the urging force of the torsion coil spring 17 becomes zero, that is, at a position where the set compression ratio is obtained in the drawing. This set compression ratio can be arbitrarily determined in advance. For example, if the compression ratio does not cause knocking and is a constant compression ratio that can ensure the necessary compression ratio even at a low temperature start, the low temperature start It is possible to avoid the difficulty of starting due to insufficient compression pressure or in-cylinder temperature. The set compression ratio can be set in accordance with the set compression ratio position when the torsion coil spring 17 is initially installed. However, after installation, the biasing force is zero at the set compression ratio by using a spring with an adjustment function. It is advantageous to adjust so that

  FIG. 6 is a graph showing the relationship between the urging force and the compression ratio when another auxiliary drive source is employed. This figure is similar to FIG. 5, but the compression ratio is the set compression ratio in the vicinity of the urging force being zero. As shown, the graph is different when the dead zone is provided in the urging force. That is, in an actual device, since a frictional force or the like exists in the driven mechanism, the driving by the biasing force of the spring is not at a position where the biasing force of the torsion coil spring 17 becomes zero as shown in FIG. End at. Therefore, the movement of the cylinder block 2 stops at a compression ratio in the vicinity thereof, not at the position of the accurate set compression ratio. FIG. 6 shows a means for solving this problem, and by providing a dead zone as shown in this figure, even if the driving is finished in the vicinity of the biasing force of the spring, not in the position where it becomes zero, The compression ratio is the exact set compression ratio.

  FIG. 13 is a diagram for explaining a schematic configuration of an embodiment of the spring mechanism having the dead zone shown in FIG. 6. In this figure, the combination of the drive shaft 131 and the nut 132 converts the axial force into a rotational force. The two compression springs 135, 136 are configured to be converted, and are attached to both sides of the nut 132 via the metal pads 133, 134. FIG. 13A shows a state where the spring is in a dead zone in the vicinity where the urging force of the spring becomes zero. At the time of attachment, the spring is attached so as to be in this state with a set compression ratio. In FIG. 13B, the drive shaft 15 ′ of the worm is driven by the drive motor, the drive shaft 131 of the spring mechanism attached to the shaft end of the drive shaft 15 ′ is driven to rotate, and the nut 132 moves on the drive shaft 131. And the state which is urging | biasing the spring 136 is shown. In this figure, when the motor fails, the nut 132 is pushed in the direction of the worm drive shaft 15 ′ by the urging force of the spring 136, and the drive shaft 131 is rotationally driven. Rotate. When the spring 136 is extended and the stopper 134 hits the shoulder 138 of the casing 137, the spring 136 is not completely biased, but cannot extend any further and the nut 132 is not pushed. The rotation of the drive shaft 131 stops, and the compression ratio becomes the initially set compression ratio.

  FIG. 7 is a graph showing the relationship between the urging force and the compression ratio when still another auxiliary drive source is employed, so that the compression ratio becomes the set compression ratio on the low compression ratio side when the urging force is near zero. It is a graph at the time of employ | adopting non-linear biasing force. By employing such an auxiliary drive source having non-linearity, it is possible to obtain substantially the same effect as in FIG. For example, in the spring mechanism shown in FIG. 13, the coil springs 135 and 136 and the metal pads 133 and 134 are removed, and a plurality of disc springs are stacked on both sides of the nut 132 (not shown). Can be obtained by loading.

  FIG. 8 is a diagram illustrating a schematic configuration of the embodiment in the case where the linear solenoid 81 is further applied to the same variable compression ratio internal combustion engine as FIG. FIG. 9 is a diagram of the torsion coil spring 17 and the linear solenoid 81 connected in series to the torsion coil spring 17 in the direction of arrow A in FIG. 8, and (a) is a state in which the operating length of the linear solenoid 81 is most retracted. (B) is a figure of the state which the operating length of the linear solenoid 81 extended most.

  That is, in this figure, a linear solenoid 81 is further connected in series to the torsion coil spring 17, and the linear solenoid 81 is fixed to a fixed point in the crankcase 1. Therefore, in FIGS. 4, 5, 6, and 7, when the motor 16 that drives the variable compression ratio mechanism fails, the force of the biased spring acts and the compression ratio is fixed at a predetermined value. In this drawing, the compression ratio can be further changed in addition to the action of the urging force of the torsion coil spring 17 by expanding and contracting the operating length of the linear solenoid 81.

  FIG. 10 is a graph showing the relationship between the biasing force of the spring and the compression ratio when the spring and the linear solenoid shown in FIG. 8 are used. The operation length of the linear solenoid 81 is controlled to further change the compression ratio. It is a graph showing that. In this figure, typically, two graphs (a) and (a) of the case where the operating length of the linear solenoid is retracted most ((a) in FIG. 9) and the case where it is most extended ((b) in FIG. 9) b), the compression ratio can be controlled in the region sandwiched between the graphs (a) and (b) by controlling the operating length of the linear solenoid 81. In this figure, when the operating length of the linear solenoid is maximized ((b) of FIG. 9), the biasing force of the spring and the driving force of the linear solenoid cooperate to obtain a predetermined compression ratio. The urging force of the spring is smaller than the urging force of the graph (a) in the case where the operating length of the linear solenoid is most retracted ((a) of FIG. 9), and is represented by the graph (b).

Therefore, when the motor breaks down and the compression ratio returns to a predetermined position due to the biasing force of the spring, the operating length of the linear solenoid is controlled between (a) and (b) in FIG. The compression ratio between the two compression ratios represented by the points A ₁ and B ₁ in FIG. 10 can be controlled. Therefore, by controlling the linear solenoid by the ECU, for example, optimization control within a relatively narrow range can be performed so as to obtain an optimum starting compression ratio suitable for the temperature of the internal combustion engine at the time of starting.

  On the other hand, when the motor has not failed, the urging force and compression of the spring are reduced in a range between the straight line (a) and the straight line (b) in FIG. Ratio relationships can be selected. Such a utilization method will be described with reference to FIG.

  FIG. 11 is a flowchart showing control for switching to driving by a linear solenoid when a drive motor of a variable compression ratio (VCR) mechanism fails. In other words, if the motor breaks down and the compression ratio returns to a predetermined position due to the biasing force of the spring, an abnormality that the motor has become uncontrollable is detected, the motor control is turned off, and the drive shaft can be rotated more lightly. Thus, it is advantageous to change to compression ratio control by a linear solenoid.

FIG. 12 is a flowchart showing control of the linear solenoid when the present invention is applied to a variable compression ratio internal combustion engine having a variable valve timing (VVT) mechanism. When the VVT mechanism breaks down, it is preferable to operate the internal combustion engine on the low compression ratio side, so the spring characteristics are selected by selecting the graph (a) in FIG. That is, the linear solenoid is operated with the operating length retracted as shown in FIG. Also, when the drive motor of the variable compression ratio (VCR) mechanism fails, the optimum between the two compression ratios represented by the points A ₁ and B ₁ in FIG. 10 regardless of the failure of the VVT mechanism. In order to control the compression ratio, a control similar to that shown in FIG. 11 is performed.

  In the above description, the drive source using the biasing force by the spring and the drive source in which the driving force by the linear solenoid is further added to the biasing force by the spring have been described as the auxiliary driving source of the variable compression ratio mechanism. However, the above-mentioned auxiliary drive source is not limited to these, for example, it is possible to use hydraulic pressure, and further, using an accumulator generally used in a hydraulic circuit, when the internal combustion engine is stopped, It is also possible to move the compression ratio to a predetermined compression ratio with the residual hydraulic pressure.

It is a figure explaining schematic structure of an embodiment at the time of applying the present invention to a variable compression ratio internal-combustion engine. It is a figure explaining the schematic structure of embodiment of the auxiliary drive source (spring) in the arrow A of FIG. 1 is an exploded perspective view of a variable compression ratio internal combustion engine to which the present invention is applied. It is a graph showing the relationship between the urging | biasing force added to the spring of FIG. 2, and a compression ratio, and when a urging | biasing force is zero, it is a graph in case a compression ratio becomes the lowest compression ratio. It is a graph showing the relationship between the urging | biasing force added to the spring of FIG. 2, and a compression ratio, and is a graph in case a compression ratio becomes a preset compression ratio when an urging | biasing force is zero. It is a graph showing the relationship between the urging | biasing force and compression ratio at the time of employ | adopting another auxiliary drive source (spring mechanism which has a dead zone). It is a graph showing the relationship between the urging | biasing force and compression ratio at the time of employ | adopting another auxiliary drive source (spring mechanism which has nonlinearity). It is a figure explaining the schematic structure of embodiment at the time of further applying a linear solenoid with respect to the variable compression ratio internal combustion engine same as FIG. It is a figure explaining schematic structure of embodiment of the auxiliary drive source (a spring and a linear solenoid) in arrow A of Drawing 8, and (a) is a figure of the state where the operation length of the linear solenoid was most retracted, b) is a diagram showing a state in which the operating length of the linear solenoid is maximized. It is a graph showing the relationship between the urging | biasing force added to the spring of the auxiliary drive source (a spring and a linear solenoid) of FIG. 8, and a compression ratio. It is a flowchart which shows the control which switches to the compression ratio control by a linear solenoid when the drive motor of a variable compression ratio (VCR) mechanism fails. It is a flowchart which shows control of a linear solenoid at the time of applying this invention in a variable compression ratio internal combustion engine provided with a variable valve timing (VVT) mechanism. It is a figure explaining schematic structure of embodiment of the spring mechanism which has a dead zone shown in FIG. 6, (a) is a figure showing the state which has urging | biasing force in a dead zone, (b) has applied urging | biasing force. It is a figure showing a state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Crankcase 2 Cylinder block 10 Variable compression ratio internal combustion engine 11 Worm 12 Worm wheel 13 Worm 14 Worm wheel 15, 15 'Drive shaft 16 Motor 17 Torsion coil spring 18 Crankcase side fixed part 34 Cam shaft 35 Cam shaft 81 Linear solenoid 130 Spring device 131 having dead band 131 Drive shaft 132 Nut 133 Contact metal 134 Contact metal 135 Coil spring 136 Coil spring 137 Casing 138 Shoulder 139 Shoulder

Claims (7)

A variable compression ratio internal combustion engine,
A variable compression ratio mechanism capable of changing the combustion chamber volume;
A driving source for generating a driving force for changing the compression ratio;
A driving force transmission mechanism that transmits the driving force of the driving source to the variable compression ratio mechanism;
With
Furthermore, an auxiliary drive source capable of shifting the variable compression ratio mechanism to a predetermined compression ratio when the drive source fails is provided separately from the drive source.
Variable compression ratio internal combustion engine.   The auxiliary drive source is a spring attached to the drive force transmission mechanism. When the spring is biased by the drive force of the drive source and the drive source fails, the spring The variable compression ratio internal combustion engine according to claim 1, which drives a transmission mechanism.   When the auxiliary drive source is a spring attached to the drive force transmission mechanism and a linear solenoid connected in series with the spring, and the spring is biased by the drive force of the drive source and the drive source fails The variable compression ratio internal combustion engine according to claim 1, wherein the spring and a linear solenoid connected in series to the spring drive the driving force transmission mechanism.   The variable compression ratio internal combustion engine according to claim 2 or 3, wherein the predetermined compression ratio is a compression ratio at which the lowest compression ratio is achieved.   The variable compression ratio internal combustion engine according to claim 2 or 3, wherein the predetermined compression ratio is a preset compression ratio.   The variable compression ratio internal combustion engine according to claim 3, wherein the predetermined compression ratio can be arbitrarily changed within a predetermined compression ratio range by adjusting an operating length of the linear solenoid. A variable compression ratio internal combustion engine comprising a variable valve timing mechanism,
A variable compression ratio mechanism capable of changing the combustion chamber volume;
A driving source for generating a driving force for changing the compression ratio;
A driving force transmission mechanism that transmits the driving force of the driving source to the variable compression ratio mechanism;
With
Further, an auxiliary drive source capable of shifting the variable compression ratio mechanism to a predetermined compression ratio when the drive source fails is provided separately from the drive source,
The auxiliary drive source is a spring attached to the drive force transmission mechanism and a linear solenoid connected in series with the spring, and the spring is biased by the drive force of the drive source,
When the variable valve timing mechanism fails, the operating length of the linear solenoid is moved to a position where no driving force is applied to the spring so that the variable compression ratio internal combustion engine is operated at the low compression ratio side. ,
When the drive source fails, the spring and a linear solenoid connected in series to the spring drive the drive force transmission mechanism and adjust the operating length of the linear solenoid, thereby the predetermined compression. The ratio can be arbitrarily changed within a predetermined compression ratio range.
Variable compression ratio internal combustion engine.

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