JPH06241058A - Compression ratio varying device of internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a compression ratio varying device for internal combustion engine, with which changing-over of the compression ratio is obtainable certainly. CONSTITUTION:The minor end of a connecting rod 6 is pivoted at a piston while the major end is pivoted on a crank shaft 1, and an eccentric sleeve 5 is rotatably installed in either of the connecting rod pivoted parts, and an eccentric sleeve lock means 11 is provided which can fix the rotation of the eccentric sleeve 5, and thus a compression ratio varying device for internal combustion engine is accomplished, wherein the sleeve 5 is fitted with brims 5', 5''. The brims 5', 5'' are arranged movable in a certain specified direction relative to the eccentric sleeve, and a friction clutch 53 is furnished to generate friction touch of the brims with the mating surface by pressing them to the mating surface on the crank shaft side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable compression ratio device for an internal combustion engine, and more particularly, to a substantial phase of the connecting rod due to a phase condition between a bearing hole of the connecting rod and a support shaft inserted in the bearing hole. The present invention relates to a variable compression ratio device having an eccentric sleeve of varying length.

[0002]

2. Description of the Related Art Conventionally, in a high load range where the engine load is larger than the medium load range or in a high engine speed range, knocking is not generated, but in the medium load range or below, the thermal efficiency is increased to improve fuel efficiency. For this reason, various variable compression ratio engines have been proposed in which the compression ratio can be positively changed.

As one of such variable compression ratio engines, for example, an eccentric sleeve for eccentrically arranging a bearing hole of a connecting rod and a support shaft inserted through the bearing hole in one of shaft supporting portions at both ends of a connecting rod of the engine. Some have been provided. In such a variable compression ratio device, the compression ratio is adjusted by changing the substantial length of the connecting rod according to the rotational phase of the eccentric sleeve.

Therefore, it is necessary to rotate the eccentric sleeve to the required phase and to fix it in the required phase. Generally, the eccentric sleeve mounted in this way can be freely rotated by the rotational force generated by the eccentricity of the load from the piston and the reaction force from the support shaft. The lock mechanism is provided with a lock pin or the like that can be moved between a locked state and a non-locked state.

In this case, the compression ratio of the engine can be changed by controlling the eccentric sleeve locking means. Such a conventional variable compression ratio device will be specifically described with reference to the drawings. That is, as shown in FIG. 7, the small end of the connecting rod 6 is pivotally supported by the piston pin 7 of the piston 8, and the large end thereof is pivotally supported by the crank pin 2 of the crankshaft.

Further, an eccentric sleeve 5 as shown in FIGS. 8 and 9 is rotatably provided at the pivotal support portion at the large end of the connecting rod 6. This eccentric sleeve 5
Is formed so that the center of its inner circle (the hole through which the crank pin 2 is inserted) is eccentric with respect to the center of the outer circle (the bearing hole of the connecting rod 6). Further, as shown in FIG. 8, the variable compression ratio device is provided with eccentric sleeve locking means 11. The eccentric sleeve locking means 11 has a lock pin 12 as a pin member that can move in the axial direction of the eccentric sleeve 5 (that is, the axial direction of the crankshaft).
For example, it is driven by the hydraulic pressure of hydraulic oil. By engaging the lock pin 12 with one of two engaging grooves 5a and 5b formed in the eccentric sleeve 5 which will be described later, the rotation of the eccentric sleeve 5 can be fixed at two positions. You can do it.

Further, as shown in FIG. 9, the eccentric sleeve 5
At both ends thereof, there are flange-shaped brims 5'protruding in the outer circumferential direction so as to sandwich the large end of the connecting rod 6, and one of the brims 5'is rotated by the eccentric sleeve 5 and the connecting sleeve 6 is connected. The position where the center axis of the bearing hole of the rod 6 is located below the center axis of the crank pin 2 [Fig.
The state of (A)] is formed with an engagement groove 5a that can be engaged with the lock pin 12.

The other brim 5'is located at a position such that the central axis of the bearing hole of the connecting rod 6 is above the central axis of the crank pin 2 (the state on the right side of FIG. 7A). The engaging groove 5b is formed so that it can be engaged with the lock pin 12 when it is opened. And the lock pin 12
Is engaged with the engagement groove 5a of the eccentric sleeve 5, the effective length of the connecting rod 6 is contracted, so that a low compression ratio can be realized, and the lock pin 12 is engaged with the engagement groove 5b. When engaged with, the substantial effective length of the connecting rod 6 is extended, and a high compression ratio can be realized.

By the way, as shown in FIG. 8, a stopper pin 50 is provided on the connecting rod 6 in parallel with the axial direction of the crankshaft. In addition, FIG.
As shown in FIG. 3, a stopper contact portion 5c is formed on the brim 5'of the eccentric sleeve 5. This stopper contact part 5
The c is formed so as to contact the stopper pin 50 when the eccentric sleeve 5 rotates by a predetermined amount, and elastically restricts the rotation at a predetermined rotational position when the eccentric sleeve 5 rotates. .

For this reason, a hydraulic damper 51 is provided at the base of the stopper pin 50 in the connecting rod 6. The hydraulic damper 51 cushions the impact when the eccentric sleeve 5 rotates and the stopper contact portion 5c contacts the stopper pin 50. The operation of such a variable compression ratio device will be described by taking the switching from the low compression ratio state to the high compression ratio state as an example.

This switching is performed by the eccentric sleeve locking means 1
This is performed by driving the lock pin 12 by means of 1. At this time, first, the lock pin 12 moves and is disengaged from the engagement groove 5a, and is stored in the connecting rod 6. Then, since the eccentric sleeve 5 can rotate relative to the connecting rod 6, the eccentric sleeve 5 rotates due to the in-cylinder explosive force of the engine and the inertial force due to the rotational force of the crankshaft. At this time, the lock pin 12 is urged (or pressed) by the hydraulic pressure or the like against the brim 5'provided with the engagement groove 5b.

Then, the eccentric sleeve 5 rotates and the stopper contact portion 5c contacts the stopper pin 50, whereby the rotation of the eccentric sleeve 5 is restricted. At this time, the engagement groove 5b of the eccentric sleeve 5 is at the position of the high compression ratio state, the lock pin 12 coincides with the engagement groove 5b, and the eccentric sleeve locking means 11 is biased (or pressed) by the hydraulic pressure or the like. The lock pin 12 is engaged with the engagement groove 5b by the force, and the eccentric sleeve 5 is fixed in a high compression ratio state.

The switching from the high compression ratio state to the low compression ratio state is performed in the same manner as described above.

[0014]

By the way, as described above, the rotational force of the eccentric sleeve 5 is obtained by the in-cylinder explosion and the inertial force of the crankshaft. However, in such a conventional variable compression ratio device. It is possible that the rotation direction of the eccentric sleeve 5 due to the in-cylinder explosion differs from the rotation direction due to the inertial force.

For example, if an in-cylinder explosion occurs when the compression ratio is switched by rotating the eccentric sleeve 5 by the inertial force of the crankshaft 1, the rotational force of the eccentric sleeve 5 works in the opposite direction and the eccentric sleeve acts against the inertial force. 5 may rotate in the opposite direction, and the compression ratio may not be smoothly switched. The rotation characteristics of the eccentric sleeve 5 at this time may be as shown in FIG. 10, for example. In this graph, the vertical axis represents the rotation angle of the eccentric sleeve 5, the horizontal axis represents time, and the angle θ1 is the rotation angle of the eccentric sleeve 5 required to switch the compression ratio.

In such a case, not only the switching of the compression ratio is not smoothly performed, but also the eccentric sleeve 5 is not fixed to either the low compression ratio or the high compression ratio as shown in FIG. There is a problem that it remains in a stable state. The present invention has been devised in view of the above problems, and allows the rotation direction of the above-described eccentric sleeve to be allowed only in one direction, so that the compression ratio can be reliably switched. An object is to provide a compression ratio device.

[0017]

Therefore, in the variable compression ratio device for an internal combustion engine according to the present invention as defined in claim 1, a small end portion is pivotally supported by a piston which reciprocates in a cylinder of the internal combustion engine, and a crank. A connecting rod having a large end pivotally supported on the shaft is provided, and the bearing hole of the connecting rod and the support shaft inserted through the bearing hole are eccentric to each other on either one of the pivotal support parts at both ends of the connecting rod. In a variable compression ratio device for an internal combustion engine, wherein an eccentric sleeve is rotatably provided, and eccentric sleeve locking means capable of fixing the rotation of the eccentric sleeve at a predetermined position is provided. Is movably provided in a required direction with respect to the eccentric sleeve, and the brim is pressed against the facing surface on the crankshaft side to bring the brim into the pair. It is characterized in that the friction clutch of rubbing contact with the surface is provided.

A variable compression ratio device for an internal combustion engine according to a second aspect of the present invention, in addition to the structure according to the first aspect,
It is characterized in that the friction clutch is configured to operate by fluid pressure. Furthermore, a variable compression ratio device for an internal combustion engine according to a third aspect of the present invention is the above-mentioned first aspect.
The variable compression ratio device for an internal combustion engine according to claim 1, wherein, in addition to the structure described above, the connecting rod is provided with a hydraulic buffer mechanism for buffering an impact due to the rotation of the eccentric sleeve.

[0019]

In the variable compression ratio device for an internal combustion engine according to the first aspect of the present invention, when the compression ratio is switched, the eccentric sleeve locking means is first unlocked to move the eccentric sleeve to the connecting rod. On the other hand, it becomes possible to rotate. However, the friction clutch provided between the brim of the eccentric sleeve and the surface of the eccentric sleeve facing the brim on the crankshaft side causes the eccentric sleeve to rotate integrally with the crankshaft, so that the eccentric sleeve rotates in one direction with respect to the connecting rod. Regulated.

Then, the eccentric sleeve can rotate to a predetermined angle, and when the eccentric sleeve reaches the predetermined angle, the eccentric sleeve locking means fixes the eccentric sleeve to the connecting rod again to switch the compression ratio. Further, in the variable compression ratio device for an internal combustion engine according to the second aspect of the present invention, the friction clutch is activated by utilizing the fluid pressure, and the eccentric sleeve is rotated.

Further, in the variable compression ratio device for an internal combustion engine according to the third aspect of the present invention, the shock when the rotation of the eccentric sleeve is stopped is buffered by the hydraulic buffer mechanism.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable compression ratio device for an internal combustion engine as an embodiment of the present invention will be described below with reference to the drawings.
2 is a schematic view showing a partially broken structure thereof, FIG. 2 is a schematic perspective view showing essential parts of the structure, FIG. 3 is a schematic view showing a hydraulic path thereof, FIG. 4 is a hydraulic circuit diagram thereof, and FIG. Is a diagram for explaining the action, and FIG. 6 is a graph for explaining the action.

As shown in FIG. 1, a large end portion of the connecting rod 6 is pivotally supported by a crank pin 2 of a crankshaft 1, and a small end portion of the connecting rod 6 runs inside a cylinder of an internal combustion engine. It is pivotally supported by a piston pin of a reciprocating piston (not shown). An eccentric sleeve 5 is rotatably provided at the pivotal support portion at the large end of the connecting rod 6 so that the bearing hole of the connecting rod 6 and the crank pin 2 as a support shaft inserted through the bearing hole are mutually eccentric. ing.

The eccentric sleeve 5 is formed such that the center of its inner circumference circle (hole through which the crank pin 2 is inserted) is eccentric with respect to the center of the outer circumference circle (bearing hole of the connecting rod 6). The device is also provided with eccentric sleeve locking means 11. The eccentric sleeve locking means 11 has a lock pin 12 as a pin member that can move in the axial direction of the eccentric sleeve 5 (that is, the axial direction of the crankshaft 1).
Is driven by, for example, the hydraulic pressure of hydraulic oil. Further, the eccentric sleeve 5 has two engagement grooves 5a,
5b is formed, and by engaging the lock pin 12 with one of these engaging grooves 5a, 5b,
The rotation of the eccentric sleeve 5 can be fixed at two positions.

The eccentric sleeve locking means 11 will be described in detail. As shown in FIG. 1, a flange-like piston portion 12a is formed in the middle portion of the lock pin 12 so as to have an enlarged diameter. Lock pin with 12
Is inserted into a through hole 61 formed in the large end portion of the connecting rod 6. The through hole 61 is formed by penetrating the large end of the connecting rod 6 in the direction of the crankshaft axis 1, and a certain liquid tightness is maintained between the through hole 61 and the lock pin 12. ing.

Further, the through hole 61 is divided into two chambers 13 and 14 by the piston portion 12a of the lock pin 12, of which the chamber 13 is provided with a return spring 15. The return spring 15 biases the lock pin 12 toward the chamber 14. Also, the chambers 13, 1
Hydraulic passages 17 and 18 are connected to 4 respectively, and these chambers 13 and 14 are configured as hydraulic chambers. The pressure receiving areas on both sides of the piston portion 12a are formed to be equal.

Further, as shown in FIG. 1, the eccentric sleeve 5
Has flange-shaped brims 5 ', 5 "laterally separated from each other so as to sandwich the large end of the connecting rod 6, and one brim 5" is formed with an engagement groove 5a. An engaging groove 5b is formed in the other brim 5 '. The engagement groove 5a can engage with the lock pin 12 when the eccentric sleeve 5 rotates and the center axis of the bearing hole of the connecting rod 6 is located below the center axis of the crank pin 2. It is provided in the position.

The engaging groove 5b is located at a position where it can engage with the lock pin 12 when the center axis of the bearing hole of the connecting rod 6 is located above the center axis of the crank pin 2. It is provided. Then, as shown in FIG. 1, when the lock pin 12 moves to the right and engages with the engagement groove 5b of the eccentric sleeve 5, the connecting rod 6 is pushed upward by the eccentric sleeve 5, The eccentric sleeve 5 is fixed in this state.

This is the length of the connecting rod 6 (the distance from the center of the piston pin to the center of the crank pin).
Is equivalent to the fact that the connecting rod 6 has become longer, and the connecting rod 6 is apparently extended, and a high compression ratio can be realized. Further, the lock pin 12 moves to the left, and the engagement groove 5a of the eccentric sleeve 5 is moved.
, The connecting rod 6 is contracted downward by the eccentric sleeve 5, and the eccentric sleeve 5 is fixed in this state.

Contrary to the above, this is equivalent to shortening the length of the connecting rod 6, and the connecting rod 6 is apparently contracted, so that a low compression ratio can be realized. . The compression ratio in the low compression ratio state is set to a value at which the engine does not knock, which is almost the same as the value set in a normal engine.

By the way, as shown in FIGS. 1 and 2, the brims 5 ', 5 "are both formed separately from the cylindrical portion 5A of the eccentric sleeve 5, and the brims 5', 5" are cylindrical. It is configured to be movable in the axial direction of the crank pin 2 with respect to the portion 5A. That is, a plurality of (here, three) guide holes 5 are provided in the cylindrical portion 5A in parallel with the crank pin 2.
5 is provided so as to penetrate therethrough, and guide pins 54 are provided at the portions corresponding to the guide holes 55 of the brims 5 ′ and 5 ″.

2, the guide pins 54 of the brims 5 ', 5 "are inserted into the guide holes 55 of the cylindrical portion 5A. Further, the central portion of the guide holes 55 has a hydraulic passage. 59 is connected, whereby the space portion of the guide hole 55 is configured as a hydraulic chamber 57. Further, sufficient liquid tightness is maintained between the guide hole 55 and the guide pin 54. When hydraulic oil is supplied from the hydraulic passage 59, the left and right brims 5 ',
5 ″ is adapted to move outward along the axial direction of the crank pin 2.

Therefore, each brim 5 ', 5 "is configured to be movable in the axial direction of the crank pin 2 and is locked in the rotational direction by the guide pin 54 and the guide hole 55 to rotate integrally with the cylindrical portion 5A. Further, as shown in Fig. 1, the friction clutch 53 is constituted by the brims 5 ', 5 "and the facing surface 2A of the crank pin 2.

The friction clutch 53 has a relatively rotating brim 5 ', 5 "and a facing surface 2A of the crankpin 2.
It is like rotating the eccentric sleeve 5 with respect to the connecting rod 6 by the frictional force generated by the contact with the. In other words, when the lock pin 12 is hydraulically driven and disengages from the engagement groove 5a (or 5b) of the eccentric sleeve 5, the eccentric sleeve 5 can freely rotate with respect to the connecting rod 6. At this time, the brims 5 ', 5 "are hydraulically driven, whereby the brims 5', 5" are pressed against the facing surface 2A of the crank pin 2 and come into frictional contact with each other, and the eccentric sleeve 5 moves the crankshaft. It is designed to rotate together with 1.

Then, when the eccentric sleeve 5 rotates a predetermined amount with respect to the connecting rod 6, the lock pin 12 engages with the other engaging groove 5b (or 5a), and at this time, hydraulic oil is supplied to the hydraulic chamber 57. The supply has been cut off.
In addition, as shown in FIG. 4, the hydraulic system of the present device includes a hydraulic system for driving the lock pin 12 (a hydraulic oil supply path to the hydraulic chambers 13 and 14) and a hydraulic system for operating the friction clutch 53. (Operating oil supply path to the hydraulic chamber 57) is provided.

Therefore, first, the hydraulic system for driving the lock pin 12 will be described. The portion of the hydraulic passage 17 outside the crankshaft 1 is connected to the main gallery 23 side and the portion of the hydraulic passage 18 outside the crankshaft 1 is connected. The part is connected to the sub oil pump 24 or the main gallery 23 side. That is, the operating oil (lubricating oil) from the oil tank or the oil pan 20 is used as the operating oil of a required hydraulic pressure (hydraulic supplying standard hydraulic pressure) by the oil pump 19 with the relief valve 21.
2 is supplied to the main gallery 23, and hydraulic oil of standard hydraulic pressure is supplied from the main gallery 23 through the hydraulic passage 17.

Further, the hydraulic oil from the main gallery 23 is supplied to the sub oil pump 24 and discharged as a higher hydraulic pressure (standard hydraulic pressure + α). The hydraulic pressure from the main gallery 23 is selectively supplied to the hydraulic pressure passage 18 by the switching valve 25. That is, as shown in FIG. 4, when the switching valve 25 is set to the a position, the standard hydraulic pressure from the main gallery 23 is supplied to the hydraulic passage 18, and when the switching valve 25 is set to the b position, the sub oil passage 18 is supplied to the hydraulic passage 18. A high hydraulic pressure (standard hydraulic pressure + α) from the pump 24 is supplied.

Therefore, the switching valve 25 is set to b
When in the position, the sub oil pump 24 is connected to the hydraulic passage 18.
A high hydraulic pressure (standard hydraulic pressure + α) is supplied to the hydraulic chamber 14 and the high hydraulic pressure is supplied to the hydraulic chamber 14. At this time, since the standard hydraulic pressure from the main gallery 23 is supplied to the hydraulic chamber 13 via the hydraulic passage 17, the lock pin 12 moves rightward against the biasing force of the return spring 15. As a result, the lock pin 12 engages with the engagement groove 5b of the eccentric sleeve 5, and a high compression ratio state can be realized.

When the switching valve 25 is set to the a position, the standard hydraulic pressure from the main gallery 23 is supplied to the hydraulic passage 18, and the standard hydraulic pressure is also supplied to the hydraulic chamber 14. At this time, since the standard hydraulic pressure from the main gallery 23 is supplied to the hydraulic chamber 13 via the hydraulic passage 17, the biasing force of the return spring 15 moves the lock pin 12 to the left. As a result, the lock pin 12 is engaged with the engagement groove 5a of the eccentric sleeve 5,
A low compression ratio state can be realized.

Reference numeral 26 in FIG. 4 is a relief valve. The relief valve 26 adjusts the difference between the standard hydraulic pressure + α and the standard hydraulic pressure to be constant.
Further, reference numeral 27 is an oil control valve for switching control of the switching valve 25. When the oil control valve 27 is set to the a position, the pilot oil pressure of the switching valve 25 is lowered to bring the switching valve 25 to the a position. When the oil control valve 27 is in the b position, the switching valve 2
5 pilot oil pressure went up and switching valve 25
Can be set to the b position.

Next, the hydraulic system for actuating the friction clutch 53 will be described. As shown in FIG.
Is connected to the above-mentioned oil pump 19 through the crank journal 3 and the journal cap 3 '. As a result, the hydraulic oil from the oil pump 19 is pressurized to the standard hydraulic pressure and then supplied from the journal cap 3'and the crank journal 3 into the hydraulic chamber 57 through the hydraulic passage 59.

Further, as shown in FIG. 4, an oil control valve 60 is provided in this hydraulic system,
By controlling the oil control valve 60, the supply of hydraulic oil to the hydraulic chamber 57 is controlled. In other words, this oil control valve 60
Is set to the a position, the hydraulic pressure from the oil pump 19 is supplied to the hydraulic chamber 57 via the hydraulic passage 59, and when the oil control valve 60 is set to the b position, the oil pump 19
The oil pressure from is returned to the oil pan 20.

Further, the present apparatus is provided with a controller 40 for controlling the oil control valves 27, 60. Further, an engine load sensor 41 and an engine speed sensor 42 are connected to the controller 40, and when the engine high load range or the engine high speed range which is larger than the engine medium load range is detected, the oil control valve 27 is set to the a position. When a control signal such as the above is output and a region below the engine middle load region is detected, a control signal for setting the oil control valve 27 to the b position is output.

Regarding the oil control valve 60, only when the oil control valve 27 is switched from the position a to the position b, the controller 40 keeps the oil control valve 60 a for a predetermined time.
A control signal for controlling the position is output. That is, here, only when the low compression ratio state is switched to the high compression ratio state, the brims 5 ′ and 5 ″ are driven to operate the friction clutch 53, and as soon as the compression ratio switching operation is completed, An oil control valve 6 for separating the brims 5 ', 5 "from the facing surface 2A.
0 is controlled to the b position, and the supply of hydraulic oil to the hydraulic chamber 57 is stopped.

By the way, as shown in FIGS. 1 and 2, the stopper engaging portion 5 is provided on the brim 5 ', 5 "of the eccentric sleeve 5.
c is formed. The stopper engaging portion 5c is formed so as to contact the stopper pin 50 when the eccentric sleeve 5 rotates by a predetermined amount, and restricts the eccentric sleeve 5 from rotating more than necessary. A hydraulic damper 51 as a hydraulic buffer mechanism is provided at the base of the stopper pin 50 in the connecting rod 6.

The hydraulic damper 51 is not shown,
For example, the return spring and the hydraulic oil serve to buffer the shock input to the stopper pin 50 and to damp the vibration.
The durability of the can be improved.
For this reason, a hydraulic passage 59 'for supplying hydraulic oil into the hydraulic damper 51 is also provided. The hydraulic oil 59 is supplied with hydraulic oil from the oil pump 19, for example.

Since the variable compression ratio device for an internal combustion engine as one embodiment of the present invention is constructed as described above, such switching of compression ratios operates according to a flow chart shown in FIG. 5, for example. . For example, in FIG. 1, when the lock pin 12 is located on the left side (that is, although not shown, when the lock pin 12 is engaged with the engagement groove 5a of the eccentric sleeve 5), the engine load sensor 41 is provided. When a region below the engine middle load region is detected by the controller, the controller 40 controls the oil control valve 27 to the b position and the oil control valve 60 to the a position for a predetermined time.

As a result, the switching valve 25 also b
Is controlled to the position, and the sub oil pump 2 is placed in the hydraulic chamber 14.
4 through the hydraulic passage 18 to a high pressure hydraulic oil (standard hydraulic pressure +
α) is supplied. Further, the hydraulic passage 1 is provided in the hydraulic chamber 13.
The hydraulic oil of standard hydraulic pressure is supplied from the main gallery 23 via 7 (step S1). The differential pressure α in the hydraulic chambers 13 and 14 acts on the piston portion 12a, so that the lock pin 12 moves to the right and the engaging groove 5a.
The lock pin 12 is stored in the connecting rod 6 while being separated from the lock rod 12. At this time, the rotation of the connecting rod 6 and the eccentric sleeve 5 becomes free (step S2).

Almost at the same time, the oil control valve 60 is controlled to the a position to supply hydraulic oil to the hydraulic chamber 57 of the eccentric sleeve 5 (step S).
5) The brims 5 ', 5 "are pressed against the facing surface 2A (step S6), and the friction clutch 53 causes the eccentric sleeve 5 to rotate integrally with the crankshaft 1. That is, the brims 5', 5". The eccentric sleeve 5 rotates due to the frictional force generated between "" and the facing surface 2A (step S3).

This rotation is restricted by the friction clutch 53 in only one direction (that is, the rotation direction of the crankshaft 1). Therefore, for example, when the eccentric sleeve 5 is rotating due to a frictional force, even if an in-cylinder explosion that attempts to rotate the eccentric sleeve 5 in a direction opposite to the rotating direction occurs, the friction clutch 53 The action prevents the eccentric sleeve 5 from rotating in the reverse direction.

During this time, since the lock pin 12 receives a force to the right due to the hydraulic pressure, it is in contact with the surface of the brim 5'on the side of the connecting rod 6, but the eccentric sleeve 5 rotates by a predetermined amount and is engaged. When the positions of the groove 5b and the lock pin 12 coincide with each other, the lock pin 12 enters the engaging groove 5b to lock the eccentric sleeve 5 (step S4). And
Almost at the same time, the oil control valve 60 is controlled to the b position. As a result, the supply of hydraulic oil to the hydraulic chamber 57 is stopped, so that the brims 5 ', 5 "move away from the facing surface of the crankpin 2 (step S7).

The eccentric sleeve 5 is rotated and the lock pin 12 is engaged with the engaging groove 5b, whereby the eccentric sleeve 5 is switched. As a result, the length of the connecting rod 6 is as if it were extended,
A high compression ratio can be reliably realized. Further, the supply of the operating oil pressure to the brims 5 ′, 5 ″ is performed at any of the timings a, b, and c shown in the flowchart of FIG. 5, but here, the case of operating at the timing b will be described. ing.

That is, the timing of a is the lock pin 1
The timing is such that the brims 5 ', 5 "are moved to the facing surface 2A side before the 2 is driven. At this timing, immediately before the lock pin 12 is disengaged from the engagement groove 5a (or 5b) of the eccentric sleeve 5. The friction clutch 53 is actuated from the above position, and at the timing of b, the friction clutch 53 is actuated immediately after the lock pin 12 is driven and disengaged from the engagement groove 5a (or 5b) of the eccentric sleeve 5. It is a timing.

Further, the timing of c is the lock pin 1
2 is disengaged from the engaging groove 5a (or 5b) of the eccentric sleeve 5 and the eccentric sleeve 5 starts rotating, and then the friction clutch 53 is activated. Further, the rotation characteristic when the eccentric sleeve 5 becomes free is as shown in the graph of FIG. 6, for example. The horizontal axis of FIG. 6 represents time and the vertical axis represents the rotation angle of the eccentric sleeve 5, and the angle θ1 is the rotation angle of the eccentric sleeve 5 required to switch the compression ratio.

Referring to FIG. 6, the rotational force applied to the eccentric sleeve 5 and the friction clutch 53 due to the in-cylinder explosion.
When the directions of the eccentric sleeve 5 and the rotational force of the eccentric sleeve 5 coincide with each other, the eccentric sleeve 5 rotates extremely smoothly as shown by the line a, and the compression ratio is switched. Also, the rotational force applied to the eccentric sleeve 5 due to the cylinder explosion and the friction clutch 5
When the direction of the eccentric sleeve 5 and the rotational force of the eccentric sleeve 3 are different from each other, for example, the line b is shown.

That is, when the friction clutch 53 rotates the eccentric sleeve 5 relative to the connecting rod 6, if there is an in-cylinder explosion that causes the eccentric sleeve 5 to rotate in the opposite direction, the eccentric sleeve 5 will rotate. Although the rotation of the eccentric sleeve 5 is temporarily stopped, the reverse rotation of the eccentric sleeve 5 is prevented by the action of the friction clutch 53.

After the cylinder explosion, the eccentric sleeve 5 rotates again, so that the rotation angle of the eccentric sleeve 5 becomes θ1.
When the angle becomes 0, the lock pin 12 engages with the engagement groove 5b and the eccentric sleeve 5 is locked. By the way, in such a case, the eccentric sleeve 5 does not always rotate by a predetermined angle θ1 ° by the second rotation like the line b, but since the eccentric sleeve 5 does not reverse, the second and subsequent rotations are not possible. Even if the eccentric sleeve 5 rotates, the eccentric sleeve 5 is surely rotated by a predetermined amount and locked. This ensures that the compression ratio is switched.

When the eccentric sleeve 5 rotates by a predetermined amount, the stopper pin 50 provided on the connecting rod 6 comes into contact with the stopper engaging portion 5c, and the eccentric sleeve 5
The rotation of the hydraulic damper 5 provided at the base of the stopper pin 50 is restricted by the excessive rotation of the stopper pin 50.
Buffered by 1. And by this, lock pin 1
2 and the engagement grooves 5a and 5b can be more reliably engaged, and the impact of the eccentric sleeve 5 can be buffered.
The durability of the eccentric sleeve 5 can be ensured.

Further, the friction clutch 53 and the lock pin 12
By operating and with the same hydraulic oil, the present device can be easily realized at a relatively low cost. Next, the switching operation from the high compression ratio state to the low compression ratio state will be described. The engine load sensor 41 detects an engine high load range larger than the engine middle load range, or the engine rotation speed sensor 42 detects. When the high engine speed range is detected, the controller 40 controls the oil control valve 27 to the a position.

As a result, the switching valve 25 is also a
The hydraulic oil is controlled to the position, and the hydraulic oil of the standard hydraulic pressure is supplied from the main gallery 23 into the hydraulic chambers 13 and 14. Therefore, a force acts on the piston portion 12a of the lock pin 12 by an amount corresponding to the biasing force of the return spring 15, the lock pin 12 moves leftward and is disengaged from the engagement groove 5b, and the lock pin 12 is connected. It is stored in the rod 6. At this time, the rotation of the connecting rod 6 and the eccentric sleeve 5 becomes free.

The oil control valve 60 is not driven by the controller 40 and remains in the b position.
As a result, hydraulic oil is not supplied to the hydraulic chamber 57 and the brims 5 ′, 5 ″ do not come into contact with the facing surfaces of the crankshaft 2. Therefore, the eccentric sleeve 5 has the inertia force of the crankshaft 1 or the cylinder. The eccentric sleeve 5 is locked by being rotated by the rotational force caused by the internal explosion, and the lock pin 12 engaging with the engaging groove 5a.

As a result, the length of the connecting rod 6 is as if it were shortened, and the low compression ratio can be surely realized. In this example,
The eccentric sleeve 5 is provided at the large end of the connecting rod 6 so that the compression ratio can be changed. The eccentric sleeve 5 is provided at the small end of the connecting rod 6 so that the compression ratio can be changed. Good.

Further, in the present embodiment, the hydraulic pressure of the hydraulic oil is used as the driving means for the lock pin 12 of the eccentric sleeve locking means 11, but other fluids (liquid or gas) may be used. Further, in this embodiment, the friction clutch 53 is configured to operate only during the switching operation from the low compression ratio state to the high compression ratio state, but this is different from the characteristic required for the engine. On the contrary, the operation may be performed only during the switching operation from the high compression ratio state to the low compression ratio state.

[0064]

As described in detail above, the first aspect of the present invention
According to the variable compression ratio device for an internal combustion engine described above, a piston reciprocating in a cylinder of the internal combustion engine is provided with a connecting end pivotally supported at a small end and a large end pivotally supported at a crankshaft, An eccentric sleeve is provided rotatably in one of the pivotal support portions at both ends of the connecting rod so that the bearing hole of the connecting rod and the support shaft passing through the bearing hole are eccentric to each other, and rotation of the eccentric sleeve is required. In a variable compression ratio device for an internal combustion engine provided with eccentric sleeve locking means that can be fixed in position,
The eccentric sleeve is provided with a brim, the brim is movably provided in a required direction with respect to the eccentric sleeve, and the brim is pressed against the facing surface on the crankshaft side to bring the brim to the facing surface. The eccentric sleeve can be reliably fixed by the structure in which the friction clutch for frictionally contacting is provided. Further, this makes it possible to reliably switch the compression ratio of the internal combustion engine.

Further, according to the variable compression ratio device for an internal combustion engine according to claim 2 of the present invention, the friction clutch is structured so as to be actuated by fluid pressure, so that the device is realized at low cost. can do. Further, according to the variable compression ratio device for an internal combustion engine according to claim 3 of the present invention, the connecting rod is provided with a hydraulic buffer mechanism for buffering an impact due to the rotation of the eccentric sleeve. The durability can be improved and the compression ratio can be reliably switched.

[Brief description of drawings]

FIG. 1 is a schematic view showing a partially broken structure of a variable compression ratio device for an internal combustion engine as an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing essential components of a variable compression ratio device for an internal combustion engine as an embodiment of the present invention.

FIG. 3 is a schematic diagram showing a part of a hydraulic path of a variable compression ratio device for an internal combustion engine as an embodiment of the present invention.

FIG. 4 is a schematic diagram showing a hydraulic circuit of a variable compression ratio device for an internal combustion engine as an embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation of the variable compression ratio device for an internal combustion engine as one embodiment of the present invention.

FIG. 6 is a graph for explaining the operation of the variable compression ratio device for an internal combustion engine as one embodiment of the present invention.

FIG. 7 is a conceptual diagram schematically showing the operation of a conventional variable compression ratio device for an internal combustion engine.

FIG. 8 is a perspective view showing a main part of a conventional variable compression ratio device for an internal combustion engine, broken away.

FIG. 9 is a perspective view showing components of essential parts of a conventional variable compression ratio device for an internal combustion engine.

FIG. 10 is a graph for explaining the operation of a conventional variable compression ratio device for an internal combustion engine.

[Explanation of symbols]

 1 Crank Shaft 2 Crank Pin 2A Opposing Face 3 Crank Journal 3'Journal Cap 4 Crank Arm 5 Eccentric Sleeve 5 ', 5 "Brim 5A Cylindrical Part 5a, 5b Engaging Groove 5c Stopper Locking Part 6 Connecting Rod 7 Piston Pin 8 Piston 11 Eccentric Sleeve Locking Means 12 Lock Pin 12a Piston Part 13, 14, 57 Hydraulic Chamber 17, 18, 59, 59 'Hydraulic Passage 15 Return Spring 19 Oil Pump 20 Oil Pan 21, 26 Relief Valve 22 Oil Filter 23 Main Gallery 24 Sub Oil pump 25 Switching valve 27,60 Oil control valve 40 Controller 41 Engine load sensor 42 Engine speed sensor 50 Stopper pin 51 Hydraulic damper 53 Friction clutch 54 Guide pin 55 Guide hole 61 Through hole

Claims (3)

[Claims] 1. A connecting rod having a small end pivotally supported by a piston reciprocating in a cylinder of an internal combustion engine and a crankshaft having a large end pivotally supported, and pivoting parts at both ends of the connecting rod. An eccentric sleeve for eccentrically rotating the bearing hole of the connecting rod and a support shaft passing through the bearing hole from each other is rotatably provided on one of the two, and an eccentric sleeve lock capable of fixing the rotation of the eccentric sleeve at a predetermined position. In a variable compression ratio device for an internal combustion engine provided with means, a brim is provided on the eccentric sleeve, the brim is movably provided in a required direction with respect to the eccentric sleeve, and the brim is provided on the crankshaft side. Internal combustion engine, characterized in that a friction clutch is provided for pressing the brim into frictional contact with the facing surface of the engine. Variable compression ratio device. 2. The variable compression ratio device for an internal combustion engine according to claim 1, wherein the friction clutch is configured to operate by fluid pressure. 3. The variable compression ratio device for an internal combustion engine according to claim 1, wherein the connecting rod is provided with a hydraulic buffer mechanism for buffering an impact due to the rotation of the eccentric sleeve.