JP2000038937A - Variable compression ratio device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid generation of sliding resistance on a driving system between an eccentric bearing and a crank pin, and between an actuator and the eccentric bearing by forming the actuator in a crank shaft or fixing the actuator to the crankshaft. SOLUTION: An actuator 31 for rotating an eccentric bearing 21 around a crank pin 12 is formed in a crankshaft 11. When operation of the actuator 31 is stopped for holding a compression ratio to low compression or high compression, it is possible to avoid generation of sliding resistance between the eccentric bearing 21 and the crank pin 12 in association with rotation of the crankshaft 11. It is also possible to avoid generation of the sliding resistance between the eccentric bearing 37 and an actuator gear 36 for driving connecting the actuator 31 and the eccentric bearing 21 to each other in association with rotation of the crankshaft 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, in order to change the compression ratio of an internal combustion engine, an eccentric bearing is inserted between a large end of a connecting rod and a crankpin, and the compression ratio is changed by rotating the eccentric bearing with respect to the crankpin. 2. Description of the Related Art A variable compression ratio device for an internal combustion engine which performs the above operation is known. An example of this type of variable compression ratio apparatus for an internal combustion engine is disclosed in
Japanese Patent Application Laid-Open No. 22717/22.

FIG. 8 is a partial cross-sectional side view of a conventional variable compression ratio device for an internal combustion engine, and FIG. 9 shows the relationship between a crankpin and an eccentric bearing at respective positions where the crankshaft rotates at different angles. FIG. 4 is a partial cross-sectional end view of the variable compression ratio device of FIG. 8 and 9, 1
01 is the connecting rod, 102 is the large end of the connecting rod, 11
1 is a crankshaft, 112 is a crankpin, 113
Is a crank arm and 114 is a crank journal. Reference numeral 121 denotes an eccentric bearing inserted between the large end portion 102 of the connecting rod and the crank pin 112 to change the compression ratio of the internal combustion engine. 131 is an actuator such as a stepping motor, 132 is an actuator sprocket, 133 is an idle sprocket,
134 is an eccentric bearing sprocket. Reference numeral 135 denotes a chain that drives and connects between the sprockets, and 141 denotes a cylinder block. As shown in FIG. 8, a conventional variable compression ratio device for an internal combustion engine rotates an eccentric bearing 121 with respect to a crankpin 112 by operating an actuator 131 to rotate an actuator sprocket 132 to change the compression ratio. can do.

[0004]

However, as shown in FIGS. 8 and 9, a conventional variable compression ratio device for an internal combustion engine is:
An actuator 131 for rotating the eccentric bearing 121 with respect to the crankpin 112 is fixed to a cylinder block 141 that is a member separate from the crankshaft 111. Therefore, even if the operation of the actuator 131 is stopped to fix the compression ratio, that is, even if the rotation of the actuator sprocket 132 is stopped, when the crankshaft 111 rotates with respect to the cylinder block 141, the eccentric bearing 121 Since it is driven and connected to the actuator 131 fixed to the cylinder block 141, it moves relative to the crankshaft 111, that is, rotates with respect to the crankpin 112. Therefore, even if the operation of the actuator 131 is stopped to fix the compression ratio, the crankshaft 1
With the rotation of 11, the sliding resistance occurs between the eccentric bearing 121 and the crankpin 112. Furthermore,
Even if the operation of the actuator 131 is stopped to fix the compression ratio, the crankshaft 111 moves relative to the actuator 131 when the crankshaft 111 is rotating with respect to the cylinder block 141. The eccentric bearing 121 supported by 111 moves relative to the actuator 131. Therefore, even if the operation of the actuator 131 is stopped to fix the compression ratio, the crankshaft 1
11, the sprocket 132, between the actuator 131 and the eccentric bearing 121,
A sliding resistance is generated in a drive system between the eccentric bearing 121 and the actuator 131 such as 133 and 134 and the chain 135.

In view of the above problems, according to the present invention, when the operation of the actuator is stopped to fix the compression ratio, sliding resistance is generated between the eccentric bearing and the crankpin with the rotation of the crankshaft. It is an object of the present invention to provide a variable compression ratio device for an internal combustion engine that avoids the occurrence of sliding resistance in a drive system between an actuator and an eccentric bearing.

[0006]

According to the present invention, an eccentric bearing is inserted between a large end of a connecting rod and a crankpin to change a compression ratio of an internal combustion engine. In the variable compression ratio device of the internal combustion engine, wherein the compression ratio is changed by rotating the eccentric bearing, an actuator for rotating the eccentric bearing with respect to the crankpin is formed in a crankshaft. Or a variable compression ratio apparatus for an internal combustion engine, the apparatus being fixed to a crankshaft.

In the variable compression ratio apparatus for an internal combustion engine, an actuator for rotating the eccentric bearing with respect to the crankpin is formed in the crankshaft or fixed to the crankshaft. Therefore, when the operation of the actuator is stopped to fix the compression ratio and the actuator is immobilized with respect to the crankshaft, even if the crankshaft is rotating, the eccentric bearing drivingly connected to the actuator is attached to the crankshaft. Can be immobile. therefore,
When the operation of the actuator is stopped in order to fix the compression ratio, it is possible to avoid the occurrence of sliding resistance between the eccentric bearing and the crankpin due to the rotation of the crankshaft. Further, when the operation of the actuator is stopped to fix the compression ratio, even if the crankshaft is rotating, the actuator and the eccentric bearing are both stationary with respect to the crankshaft. No relative movement. Therefore, when the operation of the actuator is stopped to fix the compression ratio, the rotation of the crankshaft causes the sliding between the actuator and the eccentric bearing, that is, the driving system between the actuator and the eccentric bearing. The generation of resistance can be avoided.

According to a second aspect of the present invention, the actuator rotates the eccentric bearing according to the hydraulic pressure supplied to the actuator. A ratio device is provided.

According to the third aspect of the present invention, the compression ratio can be continuously adjusted between the maximum compression ratio and the minimum compression ratio. A compression ratio device is provided.

The variable compression ratio device for an internal combustion engine according to the second and third aspects has a hydraulic actuator capable of rotating an eccentric bearing according to the hydraulic pressure. Therefore, the compression ratio is continuously adjusted by controlling the hydraulic pressure. Can be continuously adjusted between a maximum compression ratio and a minimum compression ratio.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partial sectional side view of a first embodiment of a variable compression ratio apparatus for an internal combustion engine according to the present invention, FIG. 2 is a perspective view of the variable compression ratio apparatus for an internal combustion engine shown in FIG. 1, and FIG. FIG. 1 is a partial cross-sectional end view of the variable compression ratio device of the internal combustion engine of FIG. 1 showing the relationship between the crankpin and the eccentric bearing at each position where the rotation angle of the engine is different, and FIG. A graph showing
FIG. 5 is a block diagram showing a method of changing and fixing the compression ratio according to the first embodiment. 1 to 3, 1 is a connecting rod, 2 is a large end of the connecting rod, 11 is a crankshaft, 12 is a crankpin, 13 is a crank arm, 1
4 is a crank journal. Reference numeral 21 denotes an eccentric bearing inserted between the large end 2 of the connecting rod and the crankpin 12 to change the compression ratio of the internal combustion engine. 31
Is an actuator formed in the crankshaft 11 for rotating the eccentric bearing 21 with respect to the crankpin 12, 32 is a first hydraulic supply groove for supplying hydraulic pressure to the actuator 31, and 33 is a hydraulic supply groove for supplying the hydraulic pressure to the actuator 31. And a second hydraulic supply groove for performing the operation. Reference numeral 34 denotes a helical piston having a helical tooth profile formed on an inner diameter portion and an outer diameter portion, and reference numeral 35 denotes an actuator shaft which has a helical tooth shape formed on an outer diameter portion and is rotationally driven by reciprocating motion of the helical piston 34. 36 is an actuator gear fixed to the actuator shaft 35,
An eccentric bearing gear 37 meshes with the actuator gear 36 to rotate the eccentric bearing 21.
Reference numeral 38 denotes an idle gear for transmitting the rotational driving force of the actuator 31 to an adjacent eccentric bearing (not shown);
Reference numeral 0 denotes a hydraulic control device for reciprocating the helical piston 34, and reference numeral 50 denotes a cylinder. In the present embodiment, the actuator 31 is formed in the crankshaft 11, but in another modification, the actuator 31 can be attached to the crankshaft and fixed.

Returning to the description of this embodiment, as shown in FIGS. 1 to 5, the engine load calculated from the throttle opening and the intake negative pressure and the engine speed detected by an engine speed sensor (not shown) When the number is in the high compression region shown in FIG.
Is turned off and the hydraulic pressure b is turned on. As a result, the eccentric bearing 21 is maintained at the rotation angle position shown in FIG. 3 with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine continues to be highly compressed. Subsequently, when the engine load and the engine speed change from the high compression range to the low compression range shown in FIG. 4, the hydraulic pressure a supplied to the actuator 31 is turned on and the hydraulic pressure b is turned off. As a result, the eccentric bearing 21 is moved from the rotational angle position shown in FIG.
The air-fuel mixture that is rotated by 0 ° and drawn into the cylinder of the engine is compressed at a low level.

On the other hand, when the engine load and the engine speed are in the low compression range shown in FIG.
Is turned on and the oil pressure b is turned off. As a result, the eccentric bearing 21 is maintained at a position rotated by 180 ° from the rotation angle position shown in FIG. 3 with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine is kept at a low compression. continue,
When the engine load and the engine speed change from the low compression range to the high compression range shown in FIG.
Is turned off and the oil pressure b is turned on. As a result, the eccentric bearing 21 is rotated to the rotation angle position shown in FIG.
The air-fuel mixture sucked into the cylinder of the engine is highly compressed.

As described above, in the variable compression ratio device for an internal combustion engine according to the present embodiment, the actuator 3 for rotating the eccentric bearing 21 with respect to the crankpin 12 is used.
1 is formed in the crankshaft 11. Therefore, the operation of the actuator 31 is stopped in order to maintain the compression ratio at low compression or high compression, that is, the reciprocating motion of the helical piston 34 is stopped, and the crankshaft 1 is stopped.
When the crankshaft 11 is rotating when the actuator 31 is immobilized with respect to the
The eccentric bearing 21 drivingly connected to the crankshaft 11 can be immovable with respect to the crankshaft 11. therefore,
When the operation of the actuator 31 is stopped to maintain the compression ratio at low compression or high compression, the crankshaft 11
Eccentric bearing 21 and crankpin 12
And that a sliding resistance is generated between them can be avoided. Further, when the operation of the actuator 31 is stopped in order to maintain the compression ratio at low compression or high compression, even when the crankshaft 11 is rotating, both the actuator 31 and the eccentric bearing 21 are immovable with respect to the crankshaft 11. Therefore, the actuator 31 and the eccentric bearing 21 do not move relative to each other. Therefore, to maintain the compression ratio at low or high compression, the actuator 3
When the operation of the crankshaft 11 is stopped, the actuator gear 36 and the eccentric bearing gear which drive-connect between the actuator 31 and the eccentric bearing 21, that is, between the actuator 31 and the eccentric bearing 21 with the rotation of the crankshaft 11. 37 can be prevented from generating sliding resistance.

Hereinafter, a second embodiment of the variable compression ratio apparatus for an internal combustion engine according to the present invention will be described. The configuration of the present embodiment is the same as the configuration of the first embodiment shown in FIGS. This embodiment differs from the first embodiment in the relationship between the engine speed, the engine load, and the compression ratio, and the method of changing and fixing the compression ratio. FIG. 6 is a graph showing the relationship between the engine speed, the engine load, and the compression ratio according to the second embodiment, and FIG. 7 is a block diagram showing the method of changing and fixing the compression ratio according to the second embodiment. As shown in FIGS. 1 to 3, 6 and 7, the engine load calculated from the throttle opening and the intake negative pressure and the engine speed detected by an engine speed sensor (not shown) are shown in FIG. 6. In the high-compression region shown in (1), the hydraulic pressure a supplied to the actuator 31 is turned off and the hydraulic pressure b is turned on. As a result, the eccentric bearing 21 is maintained at the rotation angle position shown in FIG. 3 with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine continues to be highly compressed. Next, the engine load and the engine speed are shown in FIG.
Is changed from the high compression range to the low compression range, the hydraulic pressure a supplied to the actuator 31 is turned on and the hydraulic pressure b is turned off. As a result, the eccentric bearing 21
Is rotated by 180 ° from the rotation angle position shown in FIG. 3 with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine is compressed at a low level. Alternatively, when the engine load and the engine speed change from the high compression region to the medium compression region shown in FIG. 6, first, the hydraulic pressure a supplied to the actuator 31 is turned on, and the hydraulic pressure b is turned off. When it is determined that the compression ratio has reached a desired compression ratio based on the piston position and the eccentric bearing phase, the hydraulic pressure a supplied to the actuator 31 is maintained at the balanced hydraulic pressure Ba, and the hydraulic pressure b is changed to the balanced hydraulic pressure Bb (= Ba) is maintained. As a result, the eccentric bearing 21 is
2 is rotated by a desired angle from the rotation angle position shown in FIG. 3, and the air-fuel mixture sucked into the cylinder of the engine is medium-compressed.

On the other hand, when the engine load and the engine speed are in the low compression range shown in FIG.
Is turned on and the oil pressure b is turned off. As a result, the eccentric bearing 21 is maintained at a position rotated by 180 ° from the rotation angle position shown in FIG. 3 with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine is kept at a low compression. continue,
When the engine load and the engine speed change from the low compression range to the high compression range shown in FIG.
Is turned off and the oil pressure b is turned on. As a result, the eccentric bearing 21 is rotated to the rotation angle position shown in FIG.
The air-fuel mixture sucked into the cylinder of the engine is highly compressed. Alternatively, FIG.
When the pressure changes from the low compression range to the middle compression range shown in FIG. 1, first, the hydraulic pressure a supplied to the actuator 31 is turned off and the hydraulic pressure b is turned on, and then the compression is performed based on the piston position and the eccentric bearing phase. When it is determined that the ratio has reached the desired compression ratio, the hydraulic pressure a supplied to the actuator 31 is maintained at the balanced hydraulic pressure Ba, and the hydraulic pressure b is maintained at the balanced hydraulic pressure Bb (= Ba). As a result, the eccentric bearing 21 moves the crank pin 1 to a desired rotation angle position.
2, and the air-fuel mixture sucked into the cylinder of the engine is moderately compressed.

When the engine load and the engine speed are in the medium compression range shown in FIG. 6, the hydraulic pressure a supplied to the actuator 31 is maintained at the balanced hydraulic pressure Ba, and the hydraulic pressure b is changed to the balanced hydraulic pressure Bb (= Ba). Has been maintained. As a result, the eccentric bearing 21 is maintained at a position rotated from the rotation angle position shown in FIG. 3 by a desired rotation angle with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine is compressed moderately. to continue. Subsequently, when the engine load and the engine speed change from the middle compression range to the low compression range shown in FIG.
Is turned on and the hydraulic pressure b is turned off. As a result, the eccentric bearing 21 moves from the rotational angle position shown in FIG.
The air-fuel mixture that has been rotated with respect to the crankpin 12 to a position rotated by 80 ° and drawn into the cylinder of the engine is compressed at a low level. Alternatively, when the engine load and the engine speed change from the middle compression range to the high compression range shown in FIG. 6, the hydraulic pressure a supplied to the actuator 31 is turned off and the hydraulic pressure b is turned on. As a result, the eccentric bearing 21 is rotated to the rotation angle position shown in FIG. 3 with respect to the crankpin 12, and the air-fuel mixture sucked into the cylinder of the engine is highly compressed.

According to this embodiment, the actuator 31
, The compression ratio can be continuously adjusted between the maximum compression ratio (high compression) and the minimum compression ratio (low compression).

Although only one cylinder is shown in the drawings for explaining the above-described embodiment, it goes without saying that the internal combustion engine can have a plurality of cylinders. The ratio device can control the compression ratios of all the cylinders in a synchronized manner.

[0021]

According to the first aspect of the present invention, when the operation of the actuator is stopped to fix the compression ratio, the sliding resistance is generated between the eccentric bearing and the crankpin with the rotation of the crankshaft. Occurs between the actuator and the eccentric bearing,
That is, it is possible to avoid the occurrence of sliding resistance in the drive system between the actuator and the eccentric bearing.

According to the second and third aspects of the present invention, by continuously adjusting the hydraulic pressure, the compression ratio can be continuously adjusted between the maximum compression ratio and the minimum compression ratio.

[Brief description of the drawings]

FIG. 1 is a partial sectional side view of a first embodiment of a variable compression ratio device for an internal combustion engine of the present invention.

FIG. 2 is a perspective view of the variable compression ratio device of the internal combustion engine of FIG.

FIG. 3 is a partial cross-sectional end view of the variable compression ratio device of the internal combustion engine of FIG. 1 showing a relationship between a crankpin and an eccentric bearing at respective positions where a rotation angle of a crankshaft is different.

FIG. 4 is a graph showing a relationship among an engine speed, an engine load, and a compression ratio according to the first embodiment.

FIG. 5 is a block diagram showing a method of changing and fixing a compression ratio according to the first embodiment.

FIG. 6 is a graph showing a relationship between an engine speed, an engine load, and a compression ratio according to the second embodiment.

FIG. 7 is a block diagram showing a method of changing and fixing a compression ratio according to a second embodiment.

FIG. 8 is a partial sectional side view of a conventional variable compression ratio device for an internal combustion engine.

9 is a partial cross-sectional end view of the variable compression ratio device of the internal combustion engine of FIG. 8, showing the relationship between the crankpin and the eccentric bearing at each position where the rotation angle of the crankshaft is different.

[Explanation of symbols]

 2: Large end of connecting rod 12: Crank pin 21: Eccentric bearing 31: Actuator

Claims (3)

[Claims] 1. An eccentric bearing is inserted between a large end of a connecting rod and a crankpin to change a compression ratio of an internal combustion engine, and the compression ratio is changed by rotating the eccentric bearing with respect to the crankpin. In the variable compression ratio device for an internal combustion engine, an actuator for rotating the eccentric bearing with respect to the crankpin is formed in a crankshaft or fixed to the crankshaft. Variable compression ratio device for internal combustion engines. 2. The variable compression ratio apparatus for an internal combustion engine according to claim 1, wherein the actuator rotates the eccentric bearing according to a hydraulic pressure supplied to the actuator. 3. The variable compression ratio apparatus for an internal combustion engine according to claim 2, wherein the compression ratio can be continuously adjusted between a maximum compression ratio and a minimum compression ratio.