JPH0830423B2 - Variable compression ratio device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a variable compression ratio device for an internal combustion engine.

(Prior Art) Conventionally, while preventing knocking in a high load range or a high engine speed range larger than the engine middle load range, thermal efficiency is increased in a low load range smaller than the engine middle load to improve fuel efficiency. In order to measure, various engines capable of varying the compression ratio have been proposed.

Such a compression ratio variable mechanism is disclosed in, for example, Japanese Patent Publication No. Sho 63-32972. The variable compression ratio mechanism disclosed in this publication has an eccentric bearing that eccentrically separates the bearing hole of the connecting rod and the support shaft inserted through the bearing hole from one of the shaft support portions at both ends of the connecting rod of the engine.
The load from the piston and the reaction force from the support shaft are provided so that they can rotate freely due to the rotational force generated by the eccentricity, and the rotation of the eccentric bearing is driven by driving the lock pin that is movable in the bearing radial direction. A hydraulic actuating lock means for switching between free and fixed is provided, and the pressure of the working oil supplied to the lock means is supplied from a computer which receives signals from the piston position detecting means and the operating condition detecting means. Signal is applied to the lock means at all times during the lock, and the lock means is controlled under the condition that no oil pressure is applied to the lock means during the unlocking.

[Problems to be Solved by the Invention] However, in such a conventional variable compression ratio mechanism for an internal combustion engine, the lock pin is driven in the radial direction of the bearing by the hydraulic mechanism to rotate the eccentric bearing between free and fixed. Since it is switched to, the operation of the lock pin may become uncertain due to the influence of the inertial force generated by the reciprocating motion of the connecting rod and the like.

For this reason, a variable compression ratio mechanism is also considered in which the lock pin is driven in the axial direction of the bearing so that the inertia of the reciprocating motion of the connecting rod does not affect the operation of the lock pin.

However, in such a variable compression ratio mechanism, when the compression ratio is switched, the protruding portion of the lock pin strongly collides with the engaging portion of the eccentric bearing, and the protruding portion of the lock pin or the lock pin of the eccentric bearing is There was a risk that the engaging part would break.

The present invention has been made in view of the above points, and an object thereof is to strongly collide with the engaging portion of the lock pin and the eccentric bearing when the compression ratio is switched, and thus the protruding portion or the eccentricity of the lock pin. It is an object of the present invention to provide a variable compression ratio device for an internal combustion engine capable of preventing the bearing and the engagement portion of the bearing with the lock pin from being destroyed.

[Structure of the Invention] (Means for Solving the Problems) A piston that slides in a cylinder of an internal combustion engine, and a connecting rod that has one end pivotally supported by the piston and the other end pivotally supported by a crankshaft are provided. In an internal combustion engine that changes the reciprocating motion of the piston into the rotary motion of the crankshaft,
An eccentric sleeve that is interposed between the other end of the connecting rod and the crankshaft and has an outer peripheral surface center and an inner peripheral surface center that are eccentric, and the other end of the connecting rod at both edges of the eccentric sleeve. A flange portion formed so as to be sandwiched, and a lock pin that is internally mounted so as to be retractable from both sides of the flange portion from inside the connecting rod,
A first notch portion provided on one flange portion for engaging the lock pin, a second notch portion provided on the other flange portion for engaging the lock pin, and both side circles of the flange portion. A shock absorber that has a guide notch cut out in the circumferential direction on the circumferential surface by a predetermined section and a pin guided by the guide notch, and absorbs the impact of the pin abutting both ends of the guide notch. And a variable compression ratio device for an internal combustion engine.

(Operation) A damper mechanism is provided for absorbing the rotational energy of the eccentric sleeve interposed between the other end of the connecting rod and the crankshaft. This prevents the stopper pin provided on the connecting rod from strongly colliding with the flange of the eccentric sleeve when the compression ratio is switched.

(Embodiment) A variable compression ratio device for an internal combustion engine according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a variable compression ratio device for an internal combustion engine as an embodiment of the present invention. FIG. 1 is an overall configuration diagram showing a state in a low compression ratio state, and FIG. 2 is a low compression ratio. 3 is a front view of the connecting rod showing the state when in a high compression ratio state, FIG. 3 is an overall configuration diagram showing a state in a high compression ratio state, and FIG. 4 is an overall configuration showing a state in a high compression ratio state. FIGS. 5 and 5 are enlarged cross-sectional views of the V portion of FIGS. 1 and 3, FIG. 6 is a cross-sectional view of the hydraulic drive mechanism showing a state in a low compression ratio state, and FIG. 7 is a high compression ratio state. FIG. 8 is a cross-sectional view of the hydraulic drive mechanism showing the state of FIG. 8 and FIG. 8 is a hydraulic circuit diagram for driving the hydraulic drive mechanism.

First, as shown in FIGS. 1 to 4, the connecting rod 6 is pivotally supported at its small end by a piston pin 7 of a piston 8 which reciprocates in a cylinder of a gasoline engine (internal combustion engine). The large end thereof is pivotally supported by the crank pin 2 of the crank shaft 1.

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. There is. That is, the center of the inner peripheral surface of the eccentric sleeve 5 and the center of the outer peripheral surface of the eccentric sleeve 5 are eccentric, and when the eccentric sleeve 5 is rotated from the minimum eccentric position to the outer periphery of the crankpin 2 by about 160 degrees, the eccentric sleeve 5 takes the vicinity of the maximum eccentric position. It's getting better.

Between the inner peripheral surface of the eccentric sleeve 5 and the outer peripheral surface of the crankpin 2, as shown in detail in FIG. 5, a metal bearing 9 with an inner peripheral surface of the eccentric sleeve 5 is interposed, and Outer peripheral surface of eccentric sleeve 5 and connecting rod 6
Between the inner peripheral surface of the bearing hole of the
A metal bearing 10 having an inner peripheral surface of the bearing hole is inserted. As a result, it is possible to slide between the eccentric sleeve 5 and the crankpin 2, and also between the eccentric sleeve 5 and the bearing hole of the connecting rod 6.

By the way, although the eccentric sleeve block means 11 is provided, the eccentric sleeve block means 11 is provided with a stopper pin 12 as a pin member that can move in the axial direction of the eccentric sleeve 5, that is, in the axial direction of the crankshaft 1. By operating the stopper pin 12 by the hydraulic drive mechanism 11A as the piston type fluid pressure drive mechanism, the stopper pin 12 is engaged with the two engaging portions 5a, 5b formed on the eccentric sleeve 5, and The rotation of the eccentric sleeve 5 can be fixed at two positions (near the above-mentioned minimum eccentric position and maximum eccentric position).

Further, the eccentric sleeve block means 11 will be described in detail. As shown in FIG. 6 and FIG. 7, first, in the intermediate portion of the stopper pin 12, a flange-shaped piston portion 12a is integrally provided by expanding the diameter, and the stopper pin 12 with this piston portion 12a is provided. Is fitted into a through hole formed in the large end of the connecting rod 6. The through hole penetrates the large end portion of the connecting rod 6 in the axial direction of the crankshaft and is configured as a three-step hole portion having three diameters. The small diameter hole portion located at one end portion of the stopper pin 12 is formed. The diameter of the medium-diameter hole is approximately the same as that of the piston 12a, and the diameter of the medium-diameter hole at the other end is substantially the same as that of the piston 12a.

Therefore, when the stopper pin 12 with the piston portion 12a is inserted into this through hole, the stopper pin 12 is liquid-tightly inserted in the small diameter hole portion of the through hole, and the piston portion 12a is liquid tight in the medium diameter hole portion of the through hole. Is inserted into. Then, the return spring 15 is put in, and a cap 16 having a through hole having substantially the same diameter as the large diameter portion of the through hole is further fitted.
Is fixed to the connecting rod 6 with bolts,
One end of the stopper pin 12 is liquid-tightly inserted into the small diameter portion of the through hole and the other end is liquid-tightly inserted into the through hole of the cap 16, and the middle diameter portion of the through hole is the piston portion 12a. It is divided into two chambers 13,14. The hydraulic passages 17 and 18 are connected to the chambers 13 and 14, respectively. Thus, these two chambers are configured as hydraulic chambers (fluid pressure chambers) 13 and 14 formed at both ends of the piston portion 12a. The return spring 15 is loaded in the hydraulic chamber 13 and urges the stopper pin 12 with the piston portion 12a toward the hydraulic chamber 14.
The pressure receiving areas on both sides of the piston portion 12a are set to be equal.

As a result, the piston part attached to this stopper pin 12
The piston type hydraulic drive mechanism 11A that can drive the stopper pin 12 by moving the piston portion 12a connected to the stopper pin 12 is constituted by the 12a, the hydraulic chambers 13, 14, the return spring 15, the cap 16, and the like.

As shown in FIGS. 1 to 4, the eccentric sleeve 5 has flange portions 51 and 52 axially separated from each other so as to sandwich the large end portion of the connecting rod 6, but one flange A notch-shaped engaging portion 5a is formed in a portion of the portion 51 where the eccentric sleeve 5 takes the minimum eccentric position, and a portion of the other flange portion 52 where the eccentric sleeve 5 takes the vicinity of the maximum eccentric position. A notch-shaped engaging portion 5b is formed in the. Then, the flange portions 51, 52
A guide notch 53 is formed at a position aligned with each other. Further, a cylindrical hydraulic piston 54 is attached to the bottom of the large end of the connecting rod 6.
A piston 55 is liquid-tightly inserted in the hydraulic piston 54, and pins 56 are attached to the hydraulic piston 54 from both side surfaces of the piston 55.
It is projected from windows 57 provided on both side surfaces of 54. Between the both end surfaces of the piston 55 and the side wall of the hydraulic piston 54, urging springs 58 and 59 are mounted and filled with oil. Further, the chambers on both sides inside the hydraulic piston 54 partitioned by the piston 55 are connected to the oil supply passage through orifices 60 and 61. The piston 55 is the biasing spring.
It is kept in the neutral position by the biasing force of 58 and 59.

Then, as shown in FIGS. 3 and 4, when the stopper pin 12 moves to the right and takes the first position as shown in FIGS. 3 and 7, the stopper pin 12 engages with the stopper pin 12 as shown in FIGS. The eccentric sleeve 5 is fixed to the large end portion of the connecting rod 6 in the vicinity of the maximum eccentric position by engaging with the joint portion 5b, and the stopper pin 12 is moved leftward as shown in FIGS. 1 and 6. In the state where the stopper pin 12 and the engaging portion 5a are engaged with each other as shown in FIG. 1 and FIG.
The eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position.

Then, when the eccentric sleeve 5 is fixed to the large end portion of the connecting rod 6 near the maximum eccentric position, the connecting rod 6 is apparently in the most extended state, and a high compression ratio state can be realized. When the sleeve 5 is fixed to the large end portion of the connecting rod 6 at the minimum eccentric position, the connecting rod 6 is in the most contracted state apparently and the low compression ratio state can be realized. The compression ratio in this low compression ratio state is selected so that the engine does not knock, which is almost the same as the value set in a normal engine. Therefore, the compression ratio in the high compression ratio state is set to a value higher than the value set in a normal engine.

Further, a means for applying a required hydraulic pressure (standard hydraulic pressure) to both hydraulic chambers 13 and 14 in advance through hydraulic passages 17 and 18, and a stopper for attaching the piston 12a against the urging force of the return spring 15 to the hydraulic chamber 13 side. Means for applying a hydraulic pressure (standard hydraulic pressure + α) higher than the standard hydraulic pressure to the hydraulic chamber 14 in order to move to the hydraulic pressure chamber.

That is, as shown in FIG. 1 and FIG. 3, the hydraulic passages 17 and 18 pass from the crank journal 3 of the crankshaft 1 to the crank arm 4 and further from the crank pin 2 to the metal bearing 9, the eccentric sleeve 5, and the metal. Pass through the bearing 10 and the large end of the connecting rod 6, and
It is connected to 13,14.

Since the metal bearing 9 slides between the crankpin 2 and the metal bearing 10 slides between the eccentric sleeve 5,
As shown in the figure, two endless grooves are formed on the inner peripheral surface of the metal bearings 9 and 10 and are connected to the hydraulic passages 17 and 18 that go around the inner peripheral surfaces. Has through-holes aligned with the hydraulic passages 17 and 18 formed in the eccentric sleeve 5, and the hydraulic pressure formed at the large end of the connecting rod 6 in each groove formed in the metal bearing 10. Through holes are formed so as to be aligned with the passages 17 and 18.

Further, as shown in FIG. 8, the portion of the hydraulic passage 17 outside the crankshaft is connected to the main gallery 23 side, and
A portion of the hydraulic passage 18 outside the crankshaft is connected to the sub oil pump 24 or the main gallery 23 side. That is, the oil (lubricating oil) from the oil tank or the oil pan 20 is supplied to the main gallery 23 by the oil pump 19 with the relief panel through the oil filter 22 as the oil of the required hydraulic pressure (the hydraulic pressure that supplies the standard hydraulic pressure). The standard gallery oil is supplied from the main gallery 23 through the hydraulic passage 17. In addition, the main gallery
The oil from 23 is supplied to the sub oil pump 24 and discharged as a higher oil pressure (standard oil pressure + α), but the oil pressure from this sub oil pump 24 is passed through the switching valve 25 to the main gallery. The hydraulic pressure from 23 is selectively supplied to the hydraulic passage 18.
That is, when the switching valve 25 is set to the a position as shown in FIG. 8, the standard hydraulic pressure from the main gallery 23 is supplied to the hydraulic passage 18, and when the switch valve 25 is set to the b position, the sub passage is connected to the hydraulic passage 18. A high oil pressure (standard oil pressure + α) from the oil pump 24 is supplied. That is, as shown in FIG.
When set to the position, the standard hydraulic pressure from the main gallery 23 is supplied to the hydraulic passage 18, and when the switching valve 23 is set to the b position, the high hydraulic pressure (standard hydraulic pressure + α) from the sub oil pump 24 is supplied to the hydraulic passage 18. It has become so.

Therefore, when the switching valve 25 is set to the b position, the high hydraulic pressure (standard hydraulic pressure + α) is supplied from the sub oil pump 24 to the hydraulic passage 18, and the high hydraulic pressure is supplied to the hydraulic chamber 14. At this time, this high hydraulic pressure is supplied into the hydraulic chamber 13. At this time, since the standard hydraulic pressure from the main gallery 23 is supplied into the hydraulic chamber 13 through the hydraulic passage 17, the stopper pin 12 with the piston portion 12a is resisted against the urging force of the return spring 15 and is shown in FIG. , When moving to the right as shown in FIG. 7 and taking the first position, the stopper pin 12 and the engaging portion 5b engage with each other as shown in FIGS. 3 and 4, The eccentric sleeve 5 is fixed to the large end of the connecting rod 6 near the maximum eccentric position. As a result, the connecting rod 6 is in the most expanded state in appearance, 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 supplied to the hydraulic chamber 14. At this time, since the standard hydraulic pressure is supplied from the main gallery 23 into the hydraulic chamber 13 via the hydraulic passage 17, the stopper pin with the piston portion 12a is pushed by the biasing force of the return spring 15 as shown in FIG. 2 and FIG. When it moves to the left as shown in FIG. 2 and takes the second position, the stopper pin 12 and the engaging portion 5a engage with each other as shown in FIGS.
Is fixed to the large end of the connecting rod 6 at the minimum eccentric position. As a result, the connecting rod 6 is apparently in the most contracted state, and the low compression ratio state can be realized.

The oil pump 19 and the sub oil pump 24 are adapted to be driven by the engine.

Further, reference numeral 26 in FIG. 8 is a relief valve, and the relief valve 26 is adjusted so that the differential pressure α between (standard hydraulic pressure + α) and the standard hydraulic pressure becomes constant.

Further, 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 and the switching valve 25 can be set to the a position. Oil control valve 27b
When in the position, the pilot oil pressure of the switching valve 25 rises so that the switching valve 25 can be moved to the b position.

The switching control signal from the controller 40 is input to the oil control valve 27, but the controller 40 receives the detection signals from the engine load sensor 41 and the engine speed sensor 42 and When the engine high load range or engine high speed range that is larger than the medium load range is detected, the oil control valve
When a control signal for setting 27 to the a position is detected 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.

With the above configuration, when a region under the engine load is detected, a control signal for setting the oil control valve 27 to the b position is output, so that the switching valve 25 is also set to the b position and the oil passage 24 from the oil pump 24 to the hydraulic passage 18. Is supplied to the hydraulic chamber 14 (standard hydraulic pressure +
α) is supplied. At this time, the hydraulic passage 17 is provided in the hydraulic chamber 13.
Since the standard hydraulic pressure is supplied from the main gallery 23 via the, the above high hydraulic pressure (standard hydraulic pressure + α)
The differential pressure α between the standard hydraulic pressure and the standard hydraulic pressure is applied to the piston portion 12a, and this differential pressure portion resists the biasing force of the return spring 15 and causes the stopper pin 12 with the piston portion 12a to move as shown in FIGS. 3 and 7. To the right. As a result, the stopper pin 12 takes the first position, and as shown in FIGS. 3 and 4, the stopper pin 12 and the engaging portion 5b are engaged with each other, and the eccentric sleeve 5 is near the maximum eccentric position. It is fixed to the large end of the connecting rod 6. At this time, when the stopper pin 12 and the engaging portion 5b are engaged with each other, the pin 56 comes into contact with the end of the guide notch 53, and the shock is buffered by the oil damper function. Then, the connecting rod 6 is switched to the most expanded state in appearance without being impacted by the stopper pin 12 to be in the high compression ratio state. In such a high compression ratio state, thermal efficiency is improved, thermal efficiency is improved, and fuel economy can be expected to be improved.

Further, when an engine high load range or an engine high speed range that is larger than the engine medium load range is detected, a control signal for setting the oil control valve 27 to the a position is output, so that the switching valve 25 also becomes the a position and the hydraulic pressure is increased. The standard hydraulic pressure from the main gallery 23 is supplied to both the passages 17 and 18, and the standard hydraulic pressure is supplied to the hydraulic chambers 13 and 14. As a result, the urging force of the return spring 15 causes the stopper pin with the piston portion 12a to move leftward as shown in FIGS.
As shown in FIG. 2 and FIG. 2, the stopper pin 12 and the engaging portion 5a
Engage with each other and the eccentric sleeve 5 is fixed to the large end of the connecting rod 6 at the minimum eccentric position. At this time, when the stopper pin 12 and the engaging portion 5b are engaged with each other, the pin 56 comes into contact with the end of the guide notch 53, and the shock is buffered by the oil damper function. As a result, the connecting rod 6 is switched to the most contracted state apparently without being impacted by the stopper pin 12, and the low compression ratio state is achieved. By setting the low compression ratio state in this way, knocking can be reliably avoided.

As described above in detail, according to the present invention, the impact generated between the stopper pin and the eccentric sleeve when switching the compression ratio is absorbed by the hydraulic piston, so that the stopper pin and this stopper pin are absorbed. It is possible to provide a variable compression ratio device for an internal combustion engine, which can prevent breakage of a portion of the eccentric sleeve that comes into contact with the.

[Brief description of drawings]

1 to 7 show a variable compression ratio device for an internal combustion engine as an embodiment of the present invention. FIG. 1 is an overall configuration diagram showing a state in a low compression ratio state, and FIG. Is a front view of the connecting rod showing a state in a low compression ratio state, FIG. 3 is an overall configuration diagram showing a state in a high compression ratio state, and FIG. 4 is a state in a high compression ratio state FIG. 5 is an enlarged sectional view of a portion V in FIGS. 1 and 3, FIG. 6 is a sectional view of a hydraulic drive mechanism showing a state in a low compression ratio state, and FIG. FIG. 8 is a cross-sectional view of the hydraulic drive mechanism showing the state in the high compression ratio state, and FIG. 8 is a diagram showing the hydraulic circuit thereof. DESCRIPTION OF SYMBOLS 1 ... Crank shaft, 5 ... Eccentric sleeve, 5a, 5b ... Engaging part, 9, 10 ... Metal bearing, 11 ... Eccentric sleeve block means, 13, 14 ... Chamber.

Claims (1)

[Claims] 1. A piston that slides in a cylinder of an internal combustion engine,
In the internal combustion engine, which has a connecting rod in which one end is pivotally supported by the piston and the other end is pivotally supported by the crankshaft, the reciprocating motion of the piston is converted into the rotary motion of the crankshaft, and the other end of the connecting rod is An eccentric sleeve interposed between the crankshaft and the center of the outer peripheral surface and the center of the inner peripheral surface, and a flange formed so as to sandwich the other end of the connecting rod at both edges of the eccentric sleeve. Portion, a lock pin that is installed so as to be retractable from both sides of the flange portion from inside the connecting rod, a first notch portion that is provided in the flange portion on one side and engages with the lock pin, and a flange portion on the other side. A second notch portion provided on the outer peripheral surface of the flange portion and engaging with the lock pin. A variable internal combustion engine, comprising: a notch for cutting and a pin guided by the notch for guiding, and a shock absorbing mechanism for absorbing the impact of the pin abutting both ends of the notch for guiding. Compression ratio device.