JPS6065231A - Compression ratio variable device for internal- combustion engine - Google Patents

Abstract

PURPOSE:To keep a piston sure in two stages according to a state of engine driving, by installing a lock device, which selectively locks a piston pin to either a low compression ratio position or a high compression ratio position, in space between a piston and the piston pin. CONSTITUTION:A piston pin P is made up of each of symmetrical journal parts 7, 8 and a crank part 9. An interval between a piston 2 and a piston pin P, there are provided with a first lock device L1 and a second lock device L2 locking the piston pin to either a low compression ratio position or a high compression ratio position. Bus bars of symmetrical journal parts 7, 8 and the crank part 9 are accorded with each other on the same line. Thus, since the piston is surely holdable in two stages of both low and high compression ratio positions according to a state of engine driving, thermal efficiency and output capacity in an engine are sharply improved and, what is more, stress concentration in the piston pin is as possible as reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that can variably adjust the compression ratio of an internal combustion engine in two stages.

It is known that increasing the compression ratio is an effective technical means for improving the thermal efficiency and output performance of an internal combustion engine.

However, if the compression ratio is set too high, abnormal combustion such as knocking will occur, and this tendency becomes especially pronounced when the engine is operated under high load.In fact, the high compression ratio causes a decrease in the thermal efficiency and output performance of the engine. Therefore, if the compression ratio can be variably adjusted while the engine is running, increasing the compression ratio when the engine is operated at low load and lowering it when the engine is operated at high load, it is possible to prevent knocking. Although it is possible to improve thermal efficiency and output performance by suppressing the occurrence of compression, no engine with variable compression ratio adjustment has been put into practical use.

The present invention has been made in view of the above circumstances, and includes forming a crank portion on a piston pin that connects a piston and a connecting rod, and controlling the rotation of the piston pin between a high compression ratio position and a low compression ratio position. The compression ratio can be changed in two stages by locking the piston pin in the position shown in FIG.
It is an object of the present invention to provide a variable compression ratio device for an internal combustion engine that is simple in structure and highly practical, which can be easily assembled to a piston.

According to the present invention, in order to achieve the above object, the piston pin connecting the piston pin rod, the left and right journal portions at both ends thereof, and the crank portion at the center thereof are integrally constituted by a cylindrical body.

The generatrix of the right journal part and the crank part are aligned on the same line on one side thereof, and the left and right journal parts are rotatably supported by the left and right pin bosses of the piston, and the small part of the connecting rod is attached to the crank part. A tenth lock is provided between the piston and the piston pin, the ends of which are rotatably connected, and which selectively locks the piston pin in a low compression ratio position and a high compression ratio position as the piston reciprocates. A device and a 20th device are provided.

An embodiment of the present invention will be described below with reference to the drawings.

Figures 1.2A and 2B show the engine at a low compression ratio and at the end of compression. A piston 2 that is slidably fitted into a cylinder 1 is formed with left and right pin bosses 3 and 4 that form a pair in the diametrical direction, and a piston pin P is attached to the pin bosses 3 and 4 at an angle of 5° to the sleeve. It is rotatably suspended horizontally via 6. The piston pin P consists of left and right journal parts 7 and 8 at both ends, and a crank part 9 in the center, and is located at the center of the crank part 9. 2 is eccentric with respect to the center O1 of the left and right journal portions 7, 8 by an eccentric amount e. As clearly shown in FIG. 5, the left side of the crank pin P.

The right journal parts 7, 8 and the central crank part 9 are integrally formed of a cylindrical body, and the left and right journal parts 7, 8 are integrally formed.
The generatrix lines of the crank portion 9 are aligned on the same line on one side thereof.

A disk-shaped flange portion 10 is integrally formed at the end of one journal portion 8 of the crank bin P. The crank bin P can be inserted into the bin bosses 3 and 4 from one side of the piston 2, and the flange portion 10 is accommodated in an annular recess 11 formed on the outer end surface of the one bin boss 4. As shown in FIG. 1, the flange portion 10 is provided with a high compression ratio side lock pin hole 12 and a low compression ratio side lock pin hole 13 at the top and bottom thereof.
3 is the lock pin 20□ of the 10th locking device, which will be described later.
However, in the high compression ratio side lock pin hole 12, a lock pin 202 (third and fourth A
, B) are inserted into and removed from each other.

A halved small end 14a of a connecting rod 14 is rotatably connected to the crank portion 9 of the piston pin P, and a halved large end 146 of the connecting rod 14 is connected to the crankshaft 1.
It is rotatably connected to the crank pin 15c of No. 5.

Between the piston 2 and the piston piston P, there is a hole in FIG. 2A.

As shown in B, the crank part 9 of the piston pin P is in the upward position with respect to the left and right journal parts 7 and 8, that is, the tenth position is for locking the piston pin P in the low compression position.
As shown in the locking device L1 and Figures 4A and 4B, the crank portion 9 of the piston pin P is connected to its left and right journal portions 7 and 8.
A twentieth locking device L2 for locking the piston pin P in a downward position, that is, in a high compression position, is provided in an informal manner with respect to the longitudinal centerline 1-1 of the cylinder 1.

Next, the structure of the tenth locking device L1 will be explained.

A small cylinder hole 17 parallel to the piston pin P is formed in one pin boss 4 of the piston 2, and this small cylinder hole 17. A lock piston 18 is slidably fitted inside, and the lock piston 181 opens the hydraulic chamber 19.
1 is defined. The lock piston 18. is integrally provided with a lock pin 201 that can protrude and retract from the outer end surface of the pin boss 4, and this lock pin 20 is connected to the hydraulic chamber 19. It protrudes in response to the hydraulic pressure inside the pin boss 4, and is retracted into the pin boss 4 by a return spring 21□ provided in the small cylinder hole 171.

The hydraulic chamber 191 of the small cylinder hole 171 has an oil passage 22 formed in the piston pin P. The oil supply passage 231 is connected to the connecting rod 14 through the connecting rod 14, and this oil supply passage 2
3. is the main oil supply passage 24 formed in the crankshaft 15. The hydraulic pressure source 26 is connected to the hydraulic pressure source 26 via the hydraulic pressure controller 25 .

Said oil passage 22. is the lock pin 20 as shown in Figure 1.
When the piston pin P is rotated to the low compression ratio position, both open ends thereof are connected to the hydraulic chamber 19.1. and an oil supply path 231. When the hydraulic pressure controller 25 detects high-load operation of the engine, the control hydraulic pressure is applied to the main oil supply passage 241, the oil supply passage 23°, the oil passage 22. Through the small cylinder hole 17
The oil pressure is supplied to the hydraulic chamber 191 in 1.

Next, the structure of the 20th locking device L2 on the high compression ratio side will be explained. This has the same structure as the 10th locking device L1 on the low compression ratio side. 1 symmetrically. A small cylinder hole 172 is formed in one pin boss 4, and a lock histone 182 is slidably fitted into this small cylinder hole 172, and a hydraulic chamber 192 is defined by this lock piston 18□. A lock pin 2o2 is integrally provided on the lock piston 182, and this lock pin 2o2 protrudes in response to the hydraulic pressure in the hydraulic chamber 192, and is retracted into the pin boss 4 by a return spring 212 provided in the small cylinder hole 172.

The hydraulic chamber 192 of the small cylinder hole 172 communicates with an oil supply passage 232 formed in the connecting rod 14 via an oil passage 222 formed in the piston pin P, and further communicates with the oil supply passage 232 formed in the connecting rod 14.
3□ passes through a main oil supply path 242 formed in the crankshaft 15 and is communicated with a hydraulic pressure source 26 via a hydraulic pressure controller 25. When the piston e7p rotates to the high compression ratio position, the oil passage 22
□ communicates with the hydraulic chamber 19 □ and the oil supply path 232 .

When the hydraulic pressure controller 25 detects low-load operation of the engine, the control hydraulic pressure is transmitted to the hydraulic chamber 19 of the small cylinder hole 172 through the main oil supply passage 242, the oil supply passage 232, and the oil passage 222.
2.

In addition, 27 in the figure is an oil passage formed in the bottle bosses 3 and 4.

Next, the operation of the embodiment of the present invention will be explained.

CD Low compression ratio operation of the engine In FIGS. 1, 2A, and 2B, the hydraulic controller 25 senses the high load operation of the engine and switches the hydraulic power source 26 to the 10th switch,
Side oil supply path 23. I will communicate with you.

Now piston pin P is the first. 20th lock device L1゜L2
Assuming that the engine is operating with the piston pin P not locked, that is, the piston pin P is free, the engine enters the suction stroke, the piston 2 descends, and its acceleration gradually decreases to zero. When the point is exceeded, a negative acceleration is applied to the piston 2 until it reaches the bottom dead center, so the piston 2 is braked during this period. However, the piston 2 tries to move downward due to the inertia caused by its mass, so it is in an unstable state.The piston pin P receives the inertia and moves toward the low compression ratio side, as clearly shown in Figure 2B. The crank part 9 is turned upward relative to the left and right journal parts 7.8. The oil passage 221 provided in the piston P on the suction path of the piston P communicates the oil supply passage 231 with the hydraulic chamber 191 in the small cylinder hole 171 of the 10th locking device, and the low compression ratio side lock pin hole 13. comes to coincide with the lock pin 20 of the lock piston 181 (FIG. 7(a)). Therefore, the lock pin 201 is
9. The lock bin hole 1 protrudes outward under the hydraulic pressure inside.
Inserted into 3. This locks the piston pin P to the low compression ratio position (second A).

(Fig. 8). As long as pressure oil is acting in the hydraulic chamber 191, the lock pin 20. is lock bin hole 13
Since the piston 2 is kept at the low compression ratio position, it draws a motion curve C1 as shown by the two-dot chain line in FIG. ), the engine repeats the suction, compression, explosion, and exhaust strokes, and the engine operates under high load at a low compression ratio.

Furthermore, during the compression and explosion strokes, the internal pressure within the cylinder 1 is high, so the piston 2 is biased downward by that pressure and tends to stay on the low compression ratio side.
As shown in (c), there is a chance that the lock bin 201 can fit into the lock bin hole 13 even near the end of the compression and explosion strokes, so the timing of locking to the low compression ratio side by the 10th locking device is as shown in Fig. 7. (a), (b)
, ('→, 3 + 7 + 96 - near the end of each stroke of suction, compression, and explosion).
If the supply of pressure oil to the 0-switch device L1 is cut, the piston 2 will enter the 10th switch when the acceleration of the piston 2 approaches zero K during the suction or exhaust stroke and the force there is minimal. 7 traction between the lock pin 201 and the lock pin hole 13 of the device L1 is reduced, and the lock pin 20. The piston pin P is pulled out of the lock pin hole 13 and sunk into the pin boss 4 by the elastic force of the return spring 211, and the piston pin P automatically becomes free.

(11) High compression ratio operation of the engine In FIGS. 3, 4A, and 48, the hydraulic pressure controller 25 senses the low load operation of the engine and supplies the hydraulic pressure source 26 to the 20th pump L2 side via the main oil supply path 242. It is communicated with the oil supply path 23□. Now the piston pin P is the 1st and 20th lock device LI.
+L2 is not locked, that is, when the engine is operating with the piston pin P free, the engine enters the exhaust stroke and nears its end (when the internal pressure in cylinder 1 reaches atmospheric pressure , so the piston 2 moves upwardly with respect to the connecting rod 14 by its own inertia, and the piston pin P rotates about 180 degrees to move to the high compression ratio side, that is, as shown in FIGS. 4A and 8. The crank part 9 rotates downward relative to the left and right journal parts 7 and 8.

During this rotation process of the piston 2, the oil passage 222 provided on the piston pin P communicates the oil supply passage 232 with the hydraulic chamber 192 in the small cylinder hole 172 of the 20th locking device L2, and the lock bin hole 12 connects with the lock piston. 182 (FIG. 8 (2)). Therefore, the lock pin 202 is fitted into the lock pin hole 12, and the piston pin P is locked, and the piston pin P is in the high compression ratio position (4A, 8).
(Fig.) is maintained. As long as pressure oil is acting in the hydraulic chamber 192 of the 20th locking device L2, the lock pin 202
Since the piston 2 is not pulled out from the lock pin hole 12, the piston 2 is held at the high compression ratio position and draws a motion curve C2 as shown by the dotted line in Figure 6, and the piston pin P is at the high position h (dotted line). The process of suction, compression, explosion, and exhaust is repeated while being held at . When the piston 2 reaches the top dead center, the top dead center position of the piston 2 reaches a position twice as high as the eccentricity e compared to the top dead center position during low compression ratio operation, and the engine is at a high compression ratio. Low load operation is performed.

In addition, in the states shown in Fig. 8 (A') to (C'), the lock pin P
has no chance of being locked into the high compression ratio position.

When the supply of pressure oil to the small cylinder hole 172 of the 20th locking device L2 is released, the acceleration of the piston 2 is close to zero, and the lock pin 2 □ is inside the piston 2 due to the elastic force of the return spring 212, and the piston pin P and the piston 2
The locked state with the piston 2 is automatically released, and the piston 2 becomes free.

During the aforementioned switching from low compression ratio operation to high compression ratio operation, or vice versa, the piston pin P is temporarily in a free state, but when the engine is operated in this state, the piston pin P As the position changes, the piston 2 draws an irregular movement curve C3 as shown by the solid line in Figure 6, and the piston pin P moves back and forth while fluctuating up and down between high and low positions. However, this curve changes depending on the engine speed and load and is not necessarily constant.

As is clear from the above embodiments, according to the present invention, the piston pin is composed of left and right journal parts at both ends thereof and a crank part in the center thereof, and the left and right journal parts are connected to the left and right bibo parts of the piston. A tenth lock device rotatably connects the small end of the connecting rod, and is provided between the piston and the piston pin to selectively lock the piston pin in a low compression ratio position and a high compression ratio position as the piston reciprocates. and a 20th locking device, the piston can be reliably held in two positions, the high compression ratio position and the low compression ratio position, depending on the operating condition of the engine, greatly improving the thermal efficiency and output performance of the engine. can be uploaded to.

In addition, the left and right journal parts and the crank part of the piston pin are integrally formed by a cylindrical body, and the generatrix of the left and right journal parts and the crank part are aligned on the same line on one side, so the piston pin forms the crank part. However, there are very few steps and stress concentration can be reduced as much as possible, making it possible to make the piston pin more compact.Furthermore, the biton pin can be inserted from one side of the piston for assembly, making the assembly easier. Not only is this easier, but the strength of the piston itself will not be reduced.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a side view of the piston portion of the engine with the piston held at a low compression ratio position, and FIG. cross section,
Figure 2B is a schematic diagram of Figure 2A, Figure 3 is a side view of the piston part of the engine with the piston held at a high compression ratio position, and Figure 4A is a cross section taken along line 3 TVA-V, 4. Figure, 4th
Figure B is a schematic diagram of Figure 4A, Figure 5 is a J perspective view of the piston, Figure 6 is the motion curve of the piston and the position of the piston pin in the low and high compression positions and in the free state. FIG. 7 is a schematic diagram showing low compression ratio lock timing, and FIG. 8 is a schematic diagram showing high compression ratio lock timing. P... Piston pin, Ll, L2...il, 20 Tsuk device, 1... Cylinder, 2... Piston, 7, 8... Left and right journal parts, 9... Crank N, 14... connecting rod, 14. z...small end Fig. 7 '116v! J-Rank Axial Rotation Hexagonal Procedure Amendment (Method) 1. Indication of the Case 1982 Patent Application No. 173612 2. Name of the Invention Compression Ratio Variable Device for Internal Combustion Engine 3. Person making the amendment Relationship to the case Patent Applicant name (532) Honda Motor Co., Ltd. 4, Agent
Person 105 Telephone Tokyo 434-4151 5 Date of amendment order

Claims (1)

[Claims] In an internal combustion engine, a connecting rod connected to a crankshaft is connected to a piston pin that is placed horizontally on a piston that is slidably fitted into a cylinder. The left and right journal parts are integrally formed by a cylindrical body, the generatrix lines of the left and right journal parts and the crank part are aligned on the same line on one side thereof, and the left and right journal parts are connected to the left and right parts of the piston.
a right pin boss rotatably supports the connecting rod, and a small end of the connecting rod is rotatably connected to the crank portion;
Between the piston and the piston pin, a tenth locking device and a second locking device selectively lock the piston pin in a low compression ratio position and a high compression ratio position as the piston reciprocates.
1. A variable compression ratio device for an internal combustion engine, characterized in that it is equipped with a 0-switch device.