JPH05302530A - Internal combustion engine compression ratio control device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a compression ratio control device for an engine, which is capable of always exhibiting a sufficient buffering capacity without air being mixed into the buffering chamber when the compression ratio is switched. A closed space formed between a slider 42 slidably engaged with a large end cap 41 and a large end cap 41 provided at the center of the slider 42 is provided as two buffer chambers 44. And the partition part 42c for partitioning the slider 45
2 and a pair of spring members that are provided in the buffer chambers 44 and 45 to urge the slider 42 toward the center of the large end cap 41. 46 and 47, a pair of oil passages 49 and 50, which communicate with the buffer chambers 44 and 45 formed in the large end cap 41 and the hydraulic pressure supply means for switching the compression ratio,
Both ends are in contact with the buffer pin 51, and the pin guide notch 16c for restricting the rotation range of the eccentric sleeve 16 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression ratio control device for an internal combustion engine (hereinafter, abbreviated as "engine") which is adapted to switch the compression ratio via pressure oil. It is designed to reduce the impact of

[0002]

2. Description of the Related Art In general, an engine with a high compression ratio can improve fuel efficiency and the like due to an increase in thermal efficiency, as compared with a engine with a low compression ratio, but on the other hand There is a drawback that knocking is likely to occur in the rotating region and the high load region. Therefore, it is possible to change the compression ratio during the operation of the engine, for example, Japanese Patent Publication No. Sho 63-32972 and Japanese Utility Model Laid-Open No. 3-127.
No. 052, etc., the compression ratio of the engine is reduced so that knocking does not occur in the high engine speed region and high load region, while the engine compression ratio is increased in other operating regions where knocking is less likely to occur. , The fuel efficiency is improved with the increase of thermal efficiency.

FIG. 8 showing the cross-sectional structure in a state of low compression ratio in an example of such a conventional compression ratio control device, IX-I thereof.
As shown in FIG. 10 which is an enlarged and extracted portion of the stopper pin in FIGS. 9 and 8 showing the cross-sectional shape viewed from the arrow X, the crank pin 102 formed on the crank shaft 101 of the engine (not shown) and the large end of the connecting rod 103 An eccentric sleeve 104 whose outer circumferential surface is eccentric with respect to the crankpin 102 is rotatably provided between and.

During operation of the engine, it is necessary to restrain the free rotation of the eccentric sleeve 104 and to fix the eccentric sleeve 104 at a predetermined rotational position.
A stopper pin 105 that can be engaged with two locking recesses 104a, 104b formed separately from each other is provided so as to be capable of reciprocating in a direction parallel to the axis of the crankshaft 101 (left-right direction in FIG. 8). There is.

A piston 105a having a flange shape in the middle portion
The stopper pin 105, which is integrally formed with, is slidably fitted to the large end of the connecting rod 103 in a direction parallel to the axis of the crankshaft 101. The piston 105a of the stopper pin 105 divides the two oil chambers 106 and 107,
Oil passages 108, 109 facing the outer peripheral surface of the eccentric sleeve 104 communicate with the oil chambers 106, 107, respectively. Further, the oil chamber 106 of the through hole of the connecting rod 103 in which these oil passages 108 and 109 are formed.
An annular spring receiving cap 110 corresponding to the outer diameter of the stopper pin 105 is fitted on the side, and is fixed to the large end portion of the connecting rod 103 via a bolt or the like not shown. A compression coil spring 111 that biases the piston 105a toward the oil chamber 107 is interposed between the spring receiving cap 110 and the piston 105a.

A pair of flanges are formed at both ends of the eccentric sleeve 104 so as to sandwich the large end of the connecting rod 103. In the illustrated example, the large end of the connecting rod 103 takes a small eccentric position. Notch-shaped locking recess formed on one of the flanges
104a is formed, and the engagement recess 104b having a notch shape is formed in the other flange portion such that the large end of the connecting rod 103 takes a large eccentric position.

That is, the stopper pin 105 moves to the right from the state shown in FIG.
By engaging with b, the large end of the connecting rod 103 and the eccentric sleeve 104 are fixed at the large eccentric position. On the other hand, the stopper pin 105 moves to the left side and the stopper pin 1
By engaging 05 with the locking recess 104a, the large end of the connecting rod 103 and the eccentric sleeve 104 are fixed at the small eccentric position.

The oil chamber 1 is formed at the large end of the connecting rod 103.
The low pressure oil passage 114 and the high pressure oil passage 115 formed in the eccentric sleeve 104, the crank pin 102, the crank arm 112, and the crank journal 113 of the crankshaft 101 are connected to the oil passages 108 and 109 respectively communicating with the crank journals.
Pressure oil is supplied to the oil chambers 106 and 107 from the 113 side.

Since the eccentric sleeve 104 rotates relative to the large ends of the crank pin 102 and the connecting rod 103, the low pressure oil passage 114 and the high pressure oil passage formed in the crank pin 102 are formed on the inner peripheral surface of the eccentric sleeve 104. A pair of annular grooves 116, 117 that can always communicate with the oil passage 115 are formed in a close state over the entire circumference, and similarly the connecting rod 1 with which the outer peripheral surface of the eccentric sleeve 104 slides.
Also on the inner peripheral surface of the large end of 03, a pair of annular grooves 118, 119 which can be always communicated with the low pressure oil passage 114 and the high pressure oil passage 115 formed in the eccentric sleeve 104 are in close proximity to each other over the entire circumference. Has been formed.

On the other hand, a plunger 120 capable of reciprocating in the tangential direction of the crankpin 102 is provided at the tip end side of the large end of the connecting rod 103.
A hydraulic damper 121 accommodating is stored. The pair of buffer chambers 122, 123 partitioned by the plunger 120 of the hydraulic damper 121 communicate with at least one of the pair of annular grooves 118, 119 formed on the inner peripheral surface of the large end portion of the connecting rod 103 via oil passages 124, 125, respectively. For this reason, the buffer chamber 1
Pressure oil is always supplied to the inside of 22,123 through the oil passages 124,125.

A pair of windows 126 are formed at the center of the hydraulic damper 121 so as to open along the reciprocating direction of the plunger 120. The buffer pins 127 protruding from the left and right sides of the plunger 120 are provided with the windows 126. Is slidably engaged with. Further, the plunger 120 is provided in the pair of buffer chambers 122 and 123.
The compression coil springs 128 and 129 for urging the buffer pin 127 integrated with the buffer pin 127 to the central portion of the window 126 are housed respectively, and the outer periphery of the flange portion of the eccentric sleeve 104 has the eccentric sleeve 104 with respect to the buffer pin 127. When the pin guide notch 130 for restricting the rotation range is formed and the stopper pin 105 and the engaging recesses 104a, 104b are engaged with each other, either of the circumferential end portions of the pin guide notch 130 is formed. Is a buffer pin 127
It comes into contact with.

Therefore, when low-pressure oil from an oil pump (not shown) is supplied to the oil chamber 106 through the oil passage 108, the oil chamber 107
Since low-pressure oil from an oil pump (not shown) is simultaneously supplied through the oil passage 109, the compression coil spring 111
The piston 105a of the stopper pin 105 is moved by the spring force of
Move to the left as indicated by 0. As a result, the stopper pin
Since the 105 and the locking recess 104a are engaged with each other and the large end of the connecting rod 103 is held in the small eccentric position, the engine is in a low compression ratio state.

At this time, since the eccentric sleeve 104 rotates counterclockwise at a high speed, even if the stopper pin 105 and the locking recess 104a are temporarily opposed to each other, they cannot engage with each other and the buffer pin 127 Eccentric sleeve 104 to one stroke end
Will turn too much. However, the pin guide notch 13
One end of 0 is pressed against the buffer pin 127, and the rotational energy of the eccentric sleeve 104 is absorbed by the orifice effect of the oil passage 124 connected to the one buffer chamber 122. The spring force of the compression coil spring 128 in one of the buffer chambers 122 causes the stopper pin 105 and the engaging recess 104a to engage immediately after the eccentric sleeve 104 starts reverse rotation.

Conversely, when high-pressure oil from an oil pump (not shown) is supplied to the oil chamber 107 via the oil passage 109, low-pressure oil from the oil pump (not shown) enters the oil chamber 106 via the oil passage 108. Is supplied, the piston 105a of the stopper pin 105 moves rightward from the state shown in FIG. 10 against the spring force of the compression coil spring 111. As a result, the stopper pin 10
Since 5 and the engaging recess 104b are engaged with each other and the large end of the connecting rod 103 is held at the large eccentric position, the engine is in a high compression ratio state.

At this time, since the eccentric sleeve 104 rotates to the right at a high speed, even if the stopper pin 105 and the locking recess 104b are temporarily opposed to each other, they cannot engage with each other and the buffer pin 127 Eccentric sleeve 104 to the other stroke end
Will turn too much. However, the pin guide notch 13
The other end of 0 pushes against the buffer pin 127, and the rotational energy of the eccentric sleeve 104 is absorbed by the orifice effect of the oil passage 125 connected to the other buffer chamber 123. Then, by the spring force of the compression coil spring 129 in the other buffer chamber 123, the stopper pin 105 and the locking recess 104b are engaged immediately after the eccentric sleeve 104 starts reverse rotation.

[0016]

In the conventional compression ratio control device shown in FIGS. 8 to 10, the buffer pin 127 is located on the right side of the window 126 in FIG. 10 when a low compression ratio is selected. Therefore, a gap S is formed between the left end of the plunger 120 and the left side of the window 126. As a result, when the eccentric sleeve 104 is rotated to switch to a high compression ratio, the air from the outside is moved through the gap S as the plunger 120 moves.
There is a risk that it will be mixed in 3 and it will be difficult to exert a normal buffering effect. Such a problem similarly occurs when the high compression ratio is selected and is switched to the low compression ratio.

In order to avoid such a problem, the window 126 is shortened so that the gap S is not formed between the end of the plunger 120 and the both ends of the window 126 regardless of the position of the buffer pin 127, or Plunger 12 along the left-right direction in FIG.
You need to lengthen the length of 0.

However, the window 126 along the left-right direction in FIG.
If the length is shortened or the plunger 120 is lengthened, as a matter of course, the movement stroke of the plunger 120 is narrowed, and it becomes difficult to provide the hydraulic damper 121 with sufficient cushioning ability.

[0019]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a compression ratio control device for an engine, which is capable of always exhibiting a sufficient buffering capacity without air being mixed into the buffer chamber when the compression ratio is switched.

[0020]

An engine compression ratio control apparatus according to the present invention includes an eccentric sleeve rotatably fitted between a crankpin and a large end of a connecting rod, and is incorporated in the connecting rod. A stopper pin that engages with any one of a pair of engaging portions formed separately from the eccentric sleeve and switches the relative rotational position between the connecting rod and the eccentric sleeve,
In a compression ratio control device for an internal combustion engine, comprising a hydraulic pressure supply means for supplying pressure oil for urging the stopper pin toward at least one of the engaging portions, sliding on the large end cap of the connecting rod. A slider that freely engages to form a closed space with the large end cap, a partition formed in the center of the slider to divide the closed space into two buffer chambers, and the center of the slider. Formed on the large end cap, a buffer pin projecting from the portion in parallel with the crank pin, a pair of spring members provided in the buffer chamber for urging the slider toward the center of the large end cap. And a pair of oil passages that respectively communicate the buffer chamber and the hydraulic pressure supply means with each other, and a pin guide cutout portion for restricting the rotation range of the eccentric sleeve by contacting both ends with the buffer pin. is there.

[0021]

When the engagement between the stopper pin provided on the connecting rod and the one engagement portion formed on the eccentric sleeve is released,
The eccentric sleeve starts rotating relative to the connecting rod, and the stopper pin engages with the other engaging portion to switch to a predetermined compression ratio.

When the rotation phase of the eccentric sleeve rotates to a position where the stopper pin can engage with the engaging portion of the eccentric sleeve, the end portion of the pin guide cutout portion presses against the buffer pin. Here, if the rotation speed of the eccentric sleeve is too fast, the stopper pin cannot be engaged with the engaging portion of the eccentric sleeve, and after the eccentric sleeve rotates too much by the amount corresponding to the stroke end of the slider, When the eccentric sleeve is reversely rotated by the spring force of the spring material and the slider is returned to the original neutral position, the stopper pin engages with the engaging portion of the eccentric sleeve.

That is, when the slider starts to move from its neutral position due to the rotational force of the eccentric sleeve, the pressure oil in the buffer chamber located in the front in the moving direction flows out through the oil passage. At this time, the orifice effect of the oil passage is generated. Thereby, the high speed rotation of the eccentric sleeve is decelerated via the slider.

When the slider is at its reciprocating end, the buffer chamber on the side opposite to the moving direction of the slider is sealed by the end of the slider on the side opposite to the moving direction of the slider and the large end cap. Is kept in a closed state.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 showing a cross-sectional structure in a high compression ratio state in an embodiment of an engine compression ratio control apparatus according to the present invention.
As shown in FIG. 2 which is a sectional view taken along the line II-II and in which the stopper pin portion in FIG. 1 is enlarged and extracted, a crank pin 12 formed on a crank shaft 11 of an engine (not shown)
A large end portion of the connecting rod 13 is rotatably fitted in the connecting rod 13, and a piston 14 capable of reciprocating in a cylinder (not shown) of the engine is pivotally attached to the small end portion of the connecting rod 13 via a piston pin 15. Has been done.

An eccentric sleeve 16 having an outer peripheral surface eccentric to the crank pin 12 is rotatably provided between the crank pin 12 and the large end of the connecting rod 13.
In this embodiment, a metal bearing 17 integral with the eccentric sleeve 16 is interposed between the crankpin 12 and the eccentric sleeve 16, and a metal bearing integral with the connecting rod 13 is also provided between the connecting rod 13 and the eccentric sleeve 16. By interposing 18,
The eccentric sleeve 16 is designed to rotate smoothly with respect to the crank pin 12 and the connecting rod 13.

During operation of the engine, it is necessary to restrain the free rotation of the eccentric sleeve 16 and fix the eccentric sleeve 16 at a predetermined rotational position.
A stopper pin 19 capable of engaging with two locking recesses 16a, 16b formed separately from each other is provided so as to be reciprocally movable in a direction parallel to the axis of the crankshaft 11 (left and right direction in FIG. 1). There is. The stopper pin 19 integrally formed with a flange-shaped piston 19a at the intermediate portion is slidably fitted to the large end of the connecting rod 13 in a direction parallel to the axis of the crankshaft 11. There is.

The piston 19a of the stopper pin 19 is
Two oil chambers 20 and 21 formed at the large end of the connecting rod 13.
The oil chambers 20 and 21 are provided with a lubricating oil passage 24 and a switching oil passage 25, which face the outer peripheral surface of the eccentric sleeve 16 via oil passages 22 and 23 formed in the metal bearing 18, respectively. They are in communication with each other. An annular spring bearing cap 26 corresponding to the outer diameter of the stopper pin 19 is fitted on the oil chamber 20 side of the large end of the connecting rod 13, and the large end of the connecting rod 13 is inserted through a bolt or the like not shown. It is fixed to the section. Then, the spring receiving cap 26 and the piston 19a
A compression coil spring 27 that urges the piston 19a toward the oil chamber 21 is interposed between and.

A pair of flanges are formed at both ends of the eccentric sleeve 16 so as to sandwich the large end of the connecting rod 13. In this embodiment, the large end of the connecting rod 13 takes a small eccentric position. The engaging recess 16a having a cutout shape is formed on one of the flanges, and the engaging recess having a cutout shape on the other flange so that the large end of the connecting rod 13 takes a large eccentric position. 16b is formed. That is, the stopper pin 19
1 moves to the right as shown in FIGS. 1 and 3 to engage the stopper pin 19 and the locking recess 16b, so that the large end of the connecting rod 13 and the eccentric sleeve 16 are fixed at the large eccentric position. To be done. On the other hand, the stopper pin 19 moves leftward from the state shown in FIGS. 1 and 3 and engages with the locking recess 16a, so that the large end of the connecting rod 13 and the eccentric sleeve 16 at the small eccentric position. Fixed.

Here, when the large end of the connecting rod 13 is in the large eccentric position, the space between the crank pin 12 and the piston pin 15 is apparently extended and a high compression ratio state is realized. Further, when the large end of the connecting rod 13 is in the small eccentric position, the gap between the crank pin 12 and the piston pin 15 is apparently contracted and a low compression ratio state is realized.

On the inner peripheral surface of the bearing metal 18 integrally fitted to the connecting rod 13, a lubricating annular groove 28 connected to the lubricating oil passage 24 via the oil passage 22 is provided. A switching annular groove 29 connected to the switching oil passage 25 through the oil passage 23 is formed. Similarly, on the inner peripheral surface of the metal bearing 17 that is integrally fitted to the eccentric sleeve 16, there is always a lubricating oil supply passage 31 that opens to the outer peripheral surface of the crankpin 12 via the oil passage 30. The crank pin 1 is connected via the lubricating annular groove 32 that can communicate with the oil passage 33.
A switching annular groove 35, which can always communicate with the switching oil supply passage 34 opening on the outer peripheral surface of 2, is engraved.

Further, the lubricating oil passage 24 and the lubricating oil supply passage 31 can be communicated with the eccentric sleeve 16 through the oil passage 22 of the metal bearing 18 and the oil passage 30 of the metal bearing 17 at all times. A plurality of lubricating groove communicating passages 36 connected to the lubricating annular groove 32 are radially formed. Similarly, the switching oil passage 25 and the switching oil supply passage 34 can be communicated with each other through the oil passage 23 of the metal bearing 18 and the oil passage 33 of the metal bearing 17 so that the eccentric sleeve 16 has the switching. A plurality of switching groove communication passages 37 connected to the for-use annular groove 35 are radially formed.

The lubricating oil supply passage 31 opening to the outer peripheral surface of the crank pin 12 is formed from the crank arm 38 to the crank journal 39, and pressure oil (not shown) is always supplied from the crank journal 39 side to the oil chamber. It is designed to be supplied to the 20 side.

The switching oil supply passage 34 opening to the outer peripheral surface of the crank pin 12 is formed from the crank arm 38 to the crank journal 40, and when a high compression ratio is selected, this crank journal 40 side is provided. The high-pressure oil (not shown) is supplied to the oil chamber 21 side.

The metal bearing 17 and the crank pin 12
Since they rotate relative to each other, in this embodiment, the lubricating oil supply passage 31 and the switching oil supply passage 34 which are open to the outer peripheral surface of the crank pin 12 can be communicated with the inner peripheral surface of the metal bearing 17 at all times. Since the metal bearing 18 and the eccentric sleeve 16 similarly rotate relative to each other by forming annular grooves (not shown), the lubricating groove communication passage 36 formed in the eccentric sleeve 16 is formed on the inner peripheral surface of the metal bearing 18. An annular groove (not shown) that can always communicate with the switching groove communication passage 37 is formed.

On the other hand, FIG. 1 and FIG. 2 and FIG. 4 showing the cross-sectional structure of the portion of the large end cap of the connecting rod 13 and FIG. 5 showing the exploded state of this portion and the cross-sectional structure taken along the line V--V in FIG. As shown in FIG. 6, a pair of slider guide surfaces 41a along the tangential direction of the crank pin 12 are formed on the large end cap 41 of the connecting rod 13, and both end portions of these slider guide surfaces 41a are formed. End plate bracket portions 41c each having an end plate holding hole 41b are provided in a protruding manner. In the end plate holding hole 41b of the end plate bracket portion 41c, the fitting convex portion 4 protruding from the cylindrical end plate 43 surrounding the end plate bracket portion 41c is provided.
3a is fitted, and the end plate 43 is held by the end plate bracket portion 41c via the fitting convex portion 43a.

The slider 42, which forms a closed space with the large end cap 41, includes the slider guide surface 41a.
A pair of cap sliding surfaces 42a that slidably contact the end plate 43 and an inner peripheral side end plate sliding surface 42b corresponding to the outer peripheral surface of the end plate 43 are formed, and the cap sliding surface 42a is slidable with respect to the end plate 43. With this end plate sliding surface 42b that engages with the
3 is held slidably along the slider guide surface 41a of the large end cap 41. At the center of the end plate sliding surface 42b of the slider 42, a closed space formed between the slider 42 and the large end cap 41 is provided.
A partition wall 42c is formed into partitions 4 and 45, and the partition wall 42c is provided between the partition wall 42c and the end plate 43.
Compression coil springs 46 and 47 for urging the large end cap 41 toward the central portion of the large end cap 41 are respectively interposed.

As described above, in this embodiment, the fitting protrusions 43a formed on the end plate 43 are fitted into the end plate holding holes 41b of the end plate bracket portions 41c formed at both ends of the large end cap 41. Each of them is fitted, but by further using a set screw, the end plate bracket portion 41c of the large end cap 41 and the end plate 4 are attached.
3 and 3 may be securely fixed.

The pair of buffer chambers 44 and 45 partitioned by the partition wall 42c are provided at both ends of a communication groove 48 formed in the inner peripheral surface of the large end of the connecting rod 13 at the oil passages 4 respectively.
9 and 50 communicate with each other, and the communicating groove 48 is one of the lubricating annular groove 28 and the switching annular groove 29 formed on the inner peripheral surface of the large end of the connecting rod 13. Are communicated with each other via an oil groove (not shown). Therefore, the buffer chamber 4
The pressure oil is constantly supplied to the insides of the cylinders 4 and 45 through the communication groove 48 and the oil passages 49 and 50.

At the upper end of the partition wall 42c formed in the central portion of the slider 42, buffer pins 51, both ends of which project from the left and right sides of the slider 42, are inserted in a penetrating state. The buffer pin 51 projecting from the upper end surface of the wall 42c is notched in the central portion, and is configured to be flush with the upper end surface of the partition wall 42c. Further, a pin guide notch 16c for restricting the rotation range of the eccentric sleeve 16 with respect to the buffer pin 51 is formed on the outer periphery of the flange portion of the eccentric sleeve 16, and the stopper pin 1
9 is engaged with the locking recesses 16a and 16b, either of the two ends of the pin guide notch 16c is provided with the buffer pin 5.
It comes into contact with 1.

In this embodiment, regardless of the sliding position of the slider 42 with respect to the large end cap 41, the buffer chambers 44, 4
Since the length in the left-right direction of the slider 42 is set in FIG. 4 so that the inside of 5 is always partitioned by the large end cap 41, the slider 42, and the end plate 43, these buffer chambers 44, There is no problem that 45 directly communicates with the outside of the connecting rod 13.

For this reason, the conventional window 126 as shown in FIGS. 7 and 8 is unnecessary, and the connecting rod 1 is formed in the buffer chambers 44, 45 simply by extending the left and right ends of the slider 42 in FIG.
Since the closed state can be maintained with respect to the outside of the slider 3, the movement stroke of the slider 42 can be lengthened very easily, and the cushioning capacity can be improved accordingly.

Therefore, when the state shown in the drawing is switched to a low compression ratio, the eccentric sleeve 16 starts rotating counterclockwise in FIG. 2, and the rotation phase of the eccentric sleeve 16 is the locking recess of the eccentric sleeve 16. When the stopper pin 19 is rotated to a position where the stopper pin 19 can be engaged with 16a, the pin guide notch 16
The other end of c hits the buffer pin 51. Here, if the rotation speed of the eccentric sleeve 16 is too fast, the stopper pin 19 cannot engage with the locking recess 16a of the eccentric sleeve 16, and the slider 42 toward the one buffer chamber 44 side.
Eccentric sleeve 16 corresponding to the stroke end of
When the eccentric sleeve 16 is rotated in the reverse direction by the spring force of the compression coil spring 46 in the buffer chamber 44 of one side and the slider 42 is returned to the original neutral position, the locking concave portion of the eccentric sleeve 16 is rotated. The stopper pin 19 is engaged with 16a.

That is, when the slider 42 starts to move from its neutral position to the buffer chamber 44 side by the rotational force of the eccentric sleeve 16, the pressure oil in the buffer chamber 44 passes from the oil passage 49 through the communication groove 48 and the oil passage 50. However, due to the viscosity of the pressure oil and the orifice effect of the oil passage 49, the communication groove 48, and the oil passage 50, the high-speed rotation of the eccentric sleeve 16 is decelerated via the slider 42. Then, the left rotation of the eccentric sleeve 16 is temporarily stopped and the compression coil spring 46
The stopper pin 19 is engaged with the locking recess 16a of the eccentric sleeve 16 immediately after the eccentric sleeve 16 starts to rotate in the reverse direction due to the spring force.

When the rotation speed of the eccentric sleeve 16 is very slow, the buffer pin 51 does not move from the neutral state, and the stopper pin 19 remains engaged in the locking recess 16a as the eccentric sleeve 16 rotates. But in this case,
Since the rotation speed of the eccentric sleeve 16 is low, almost no impact occurs when switching the compression ratio.

The partition wall 42c gradually narrows the oil passage 49 as the slider 42 moves. As a result, the eccentric sleeve 16 has a resistance to rotation as the locking recess 16a of the eccentric sleeve 16 approaches the stopper pin 19. As a result, the restraining force against the rotation of the eccentric sleeve 16 gradually increases.

On the contrary, when the low compression ratio is switched to the high compression ratio shown in the figure, the eccentric sleeve 16 is moved to the position shown in FIG.
When the eccentric sleeve 16 starts rotating clockwise and rotates to a position where the stopper pin 19 can engage with the locking recess 16b of the eccentric sleeve 16, one end of the pin guide notch 16c It hits the buffer pin 51. Here, when the rotation speed of the eccentric sleeve 16 is too fast, the stopper pin 1 is inserted into the locking recess 16b of the eccentric sleeve 16.
9 cannot engage, and after the eccentric sleeve 16 has rotated too much by the amount corresponding to the stroke end of the slider 42 toward the other buffer chamber 45 side, the compression coil spring 47 in the other buffer chamber 45 Due to the spring force, the eccentric sleeve 16
When the slider 42 is returned to the original neutral position by rotating in the reverse direction, the stopper pin 1 is inserted into the locking recess 16b of the eccentric sleeve 16.
9 engage.

That is, when the slider 42 starts to move from its neutral position to the buffer chamber 45 side by the rotational force of the eccentric sleeve 16, the pressure oil in the buffer chamber 45 passes from the oil passage 50 through the communication groove 48 and the oil passage 49. However, due to the viscosity of the pressure oil and the orifice effect of the oil passage 50, the communication groove 48, and the oil passage 49, the high-speed rotation of the eccentric sleeve 16 is decelerated via the slider 42. Then, the right rotation of the eccentric sleeve 16 is temporarily stopped and the compression coil spring 47
The stopper pin 19 is engaged with the locking recess 16b of the eccentric sleeve 16 immediately after the eccentric sleeve 16 starts to rotate in the reverse direction due to the spring force.

When the rotation speed of the eccentric sleeve 16 is very low, the buffer pin 51 does not displace from the neutral state, and the stopper pin 19 remains engaged in the locking recess 16b as the eccentric sleeve 16 rotates. But in this case,
Since the rotation speed of the eccentric sleeve 16 is low, almost no impact occurs when switching the compression ratio.

The partition wall 42c gradually narrows the oil passage 50 as the slider 42 moves. As a result, the eccentric sleeve 16 has a resistance to rotation as the locking recess 16b of the eccentric sleeve 16 approaches the stopper pin 19. As a result, the restraining force against the rotation of the eccentric sleeve 16 gradually increases.

FIG. 7 showing a hydraulic control circuit in this embodiment.
As shown in FIG. 3, the lubricating oil supply passage 31 formed in the crank journal 39 faces the main gallery 52 outside the crankshaft 11. In addition, the crank journal 40
The switching oil supply passage 34 formed in the above is connected to a hydraulic switching valve 53 described later outside the crankshaft 11.

The pressure oil from the oil sump 54 is regulated for lubrication preset by a lubrication oil pump 56 provided with a lubrication relief valve 55, and is supplied to the main gallery 52 via an oil filter 57. .. Then, pressure oil for lubrication is supplied from the main gallery 52 through the lubricating oil supply passage 31 to the oil passage 30,
The oil is constantly supplied to the oil chamber 20 side through the lubricating groove communication passage 36, the oil passage 22, and the lubricating oil passage 24, and is also distributed and supplied to each part of the engine.

The main gallery 52 and the hydraulic pressure switching valve 53
A switching oil pump 58 for supplying high-pressure oil to the hydraulic switching valve 53 side is interposed between the oil pressure switching valve 53 and the oil pressure switching valve 53, and the switching oil supply passage 34 is connected via the hydraulic switching valve 53 to the main gallery 52.
Side or the switching oil pump 58 side, the communication state can be switched. Further, the hydraulic pressure switching valve 53 is provided with an electromagnetic control valve 59 for switching the energized state based on the operating state of the engine. By controlling the energized state for the electromagnetic control valve 59 by the control unit 60, The supply / discharge of pilot pressure from the main gallery 52 side is switched with respect to the hydraulic pressure switching valve 53,
Is driven.

That is, when the control unit 60 keeps the electromagnetic control valve 59 in the non-energized state shown in the figure based on the operating state of the vehicle, the switching oil supply passage 34 is mainly connected via the hydraulic switching valve 53. It is in communication with the gallery 52,
Low-pressure oil flows from the switching oil supply passage 34 through the oil passage 33, the switching groove communication passage 37, the oil passage 23, and the switching oil passage 25 to the oil chamber 21.
As a result of being supplied to the side, the stopper pin 19 is engaged with the locking recess 16a of the eccentric sleeve 16 which realizes a low compression ratio state by the spring force of the compression coil spring 22. On the contrary, the control unit 60 controls the electromagnetic control valve 59 based on the operating state of the vehicle.
Is maintained in the energized state, the pilot pressure from the main gallery 52 is urged to the hydraulic pressure switching valve 53, and the high pressure oil from the switching oil pump 58 is passed through the switching oil supply passage 34 to the oil chamber 2
As a result, the stopper pin 19 is engaged with the locking recess 16b of the eccentric sleeve 16 which realizes a high compression ratio state.

The switching of the compression ratio is performed based on a map preset according to the driving state of the vehicle.
Further, in the present embodiment, a switching relief valve 61 is attached in the middle of the switching oil supply passage 34, and the hydraulic pressure of the pressure oil supplied from the switching oil pump 58 to the switching oil supply passage 34 side is reduced by the compression coil spring. The stopper pin 19 resists the spring force of 27, as shown in FIG.
The pressure is adjusted for switching sufficient to be displaced to the right, and both the lubricating oil pump 56 and the switching oil pump 58 are driven by an engine (not shown).

Therefore, when the stopper pin 19 is disengaged from either one of the two engaging recesses 16a and 16b based on the command from the control unit 60, the eccentric sleeve is connected to the connecting rod 13. 16 starts relative rotation, and the stopper pin 19 engages with the other of the two engaging recesses 16a, 16b to switch to a predetermined compression ratio. At this time, the kinetic energy of the eccentric sleeve 16 relative to the connecting rod 13 is absorbed by the hydraulic damper 43, so that the stopper pin 19 is gently engaged.

[0057]

According to the compression ratio control device for an internal combustion engine of the present invention, a slider for slidably engaging a large end cap of a connecting rod to form a closed space between the large end cap and the slider is formed. At the center, a partition is formed to divide this closed space into two buffer chambers, and by extending both ends in the sliding direction of the slider, it is possible to prevent air from entering the buffer chamber. It is possible to set the moving stroke of the plunger larger than that of the above-mentioned one, and it is possible to further improve the buffering capacity when the compression ratio is switched.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part in a state in which a high compression ratio is selected in an embodiment of a compression ratio control device for an engine according to the present invention.

FIG. 2 is a sectional view taken along the line II-II.

FIG. 3 is an extracted enlarged cross-sectional view of a main part in FIG.

FIG. 4 is an extracted enlarged cross-sectional view of a portion of the large end cap shown in FIG. 2 in the present embodiment, showing a neutral state of the slider.

FIG. 5 is an exploded perspective view of a portion of the large end cap.

6 is a sectional view taken along the line VI-VI in FIG.

FIG. 7 is a hydraulic control circuit diagram in the present embodiment.

FIG. 8 is a sectional view of a main portion showing a low compression ratio state in an example of a conventional compression ratio control device for an internal combustion engine.

FIG. 9 is a sectional view taken along the line IX-IX.

10 is a cross-sectional view of a main portion of FIG. 7 extracted in an enlarged state.

[Explanation of symbols]

11 is a crank shaft, 12 is a crank pin, 13 is a connecting rod, 14 is a piston, 15 is a piston pin, 16 is an eccentric sleeve, 16a and 16b are locking recesses, 16c is a pin guide notch, 17 is a metal bearing, 18 is a metal bearing, 19 is a stopper pin, 19a is a piston, 20 and 21 are oil chambers, 22 and 2
3 is an oil passage, 24 is a lubricating oil passage, 25 is a switching oil passage,
26 is a spring bearing cap, 27 is a compression coil spring, 28
Is an annular groove for lubrication, 29 is an annular groove for switching, 30 is an oil passage, 3
1 is a lubricating oil supply passage, 32 is an annular groove for lubrication, 33 is an oil passage,
34 is a switching oil supply path, 35 is a switching annular groove, 36 is a lubricating groove communication path, 37 is a switching groove communication path, 38 is a crank arm, 39 is a crank journal, 40 is a crank journal, and 41 is a large end. Part cap, 41a is a slider guide surface, 41b is an end plate holding hole, 41c is an end plate bracket part, 42 is a slider, 42a is a cap sliding surface, 42b is an end plate sliding surface, 42
c is a partition wall, 43 is an end plate, 43a is a fitting protrusion, 44 is a buffer chamber, 45 is a buffer chamber, 46 is a compression coil spring, 47 is a compression coil spring, 48 is a communication groove, 49 is an oil passage, 50 Oil passage,
51 is a buffer pin, 52 is a main gallery, 53 is a hydraulic switching valve, 54 is an oil reservoir, 55 is a lubricating relief valve, 56 is a lubricating oil pump, 57 is an oil filter, 58 is a switching oil pump, and 59 is 59. An electromagnetic control valve, 60 is a control unit, and 61 is a switching relief valve.

Claims (1)

[Claims] 1. An eccentric sleeve rotatably fitted between a crank pin and a large end portion of a connecting rod, and a pair of engaging portions incorporated in the connecting rod and spaced apart from each other on the eccentric sleeve. A stopper pin that engages with any of the above to switch the relative rotational position between the connecting rod and the eccentric sleeve,
In a compression ratio control device for an internal combustion engine, comprising a hydraulic pressure supply means for supplying pressure oil for urging the stopper pin toward at least one of the engaging portions, sliding on the large end cap of the connecting rod. A slider that freely engages to form a closed space with the large end cap, a partition formed in the center of the slider to divide the closed space into two buffer chambers, and the center of the slider. Formed on the large end cap, a buffer pin projecting from the portion in parallel with the crank pin, a pair of spring members provided in the buffer chamber for urging the slider toward the center of the large end cap. Internal combustion engine including a pair of oil passages that respectively communicate the buffer chamber and the hydraulic pressure supply means with each other, and a pin guide cutout portion that restricts the rotation range of the eccentric sleeve by contacting both ends with the buffer pin. Compression of The control device.