JPS6065233A - Compression ratio variable device for internal- combustion engine - Google Patents

Abstract

PURPOSE:To select a piston over to two stages as well as to make a distinct improvement in thermal efficiency and output capacity, 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 the piston and the piston pin. CONSTITUTION:A piston 2 is made up of each symmetrical journal parts 7, 8 and a central crank part 9. At an interval between the piston 2 and a piston pin P, there are provided with both first and second lock devices L1 and L2 which selectively lock the piston pin P to both low and high compression ratio positions. Thus since the piston is selectable for the compression ratio position from high to low and vice versa in an accurate manner, thermal efficiency and output capacity both are sharply improvable.

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 increased too much, knocking will occur.
This tendency increases especially when the engine is operated under high load.
In fact, a high compression ratio leads to a decrease in thermal efficiency and output performance.

Therefore, it has been proposed to incorporate a hydraulic device such as a hydraulic cylinder into the piston to variably adjust the compression ratio depending on the operating condition of the engine, but this method requires a complicated structure and increases the weight of the piston. This caused problems such as rattling in the piston, and could not be put to practical use.

The present invention was made in view of the above-mentioned circumstances, and it improves the piston pin that connects the piston and the connecting rod, and locks the piston pin in two compression ratio positions, high and low, to adjust the compression ratio in two stages. It is an object of the present invention to provide a variable compression ratio device for an internal combustion engine which has a simple structure and can be used practically.

According to the present invention, in order to achieve the above-mentioned object, the piston pins are connected to the left 1. Consists of a right journal section and a central crank section that is eccentric from these journal sections and integrated with them.The left and right journal sections are rotatably supported by the left and right pin bosses of the piston, and the small end of the connecting rod can be freely rotated on the crank section. A tenth lock device and a twentieth lock are connected to the piston and the piston pin and selectively lock the piston pin in a low compression ratio position and a high compression ratio position as the piston reciprocates. We are trying to install equipment.

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 1. 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 a sleeve 5. It is rotatably suspended horizontally via 6. The piston pin P consists of left and right journal portions 7.8 at both ends and a crank portion 9 in the center, and the center o2 of the crank portion 9 is eccentric with respect to the center oHIfc of the left and right journal portions 7 and 8. I'm thinking about it.

A disk-shaped flange portion 10 is integrally formed at the end of one of the journal portions 8, and this flange portion 10 is accommodated in an annular recess 11 formed on the outer end surface of the one pin 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 on the upper and lower sides.
There is a lock pin 20 of the tenth locking device which will be described later. However, the lock bin hole 12 also has a lock bin 202 (3rd, 4A, lk
(Fig. B) are fitted in such a way that they can be inserted and removed.

A halved small end 14α of a connecting rod 14 is rotatably connected to the crank portion 9 of the piston pin P, and a halved large end 14b of the connecting rod 14 is connected to the crankshaft 1.
5 crank pin 15. is rotatably connected to.

Between the piston 2 and the piston piston P, there is a second H'1jj
-B.

As shown in the figure, 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 for locking the piston pin P in the low compression position.
Tsuk device L1, and 4th A.

As shown in FIG.
A zero-lock device L2 is provided symmetrically with respect to the longitudinal centerline tZ of the cylinder 1.

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

A small cylinder hole 171 parallel to the piston pin P is formed in one of the pin bosses 4 of the piston 2. A lock piston 181 is slidably fitted inside, and the lock piston 181 opens the hydraulic chamber 19.
．． is defined. The lock piston 18. is a lock pin 20 that can protrude and retract from the outer end surface of the pin boss 4. is integrally provided, and this lock pin 20. protrudes in response to the hydraulic pressure in the hydraulic chamber 191, and is retracted into the pin boss 4 by the small cylinder hole 17 and the return spring 21 provided therein.

Said small cylinder hole 17. The hydraulic chamber 191 is connected to the 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
31 passes through a main oil supply path 241 formed in the crankshaft 15 and is communicated with a hydraulic pressure source 26 via a hydraulic pressure controller 25.

The oil passage 221 is connected to the piston pin 2 as shown in FIG.
When the piston pin P is rotated to the low compression ratio position, both opening ends thereof are connected to the hydraulic chamber 19.01. and oil supply path 23. It is designed to communicate with 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 231, the oil passage 22. Through the small cylinder hole 1
71 has the same structure as the tenth lock device on the low compression ratio side, and is provided symmetrically with respect to the longitudinal centerline 1-1 of the cylinder 1. That is, a small cylinder hole 172 is formed in one pin boss 4, and the lock piston 18 is inserted into this small cylinder hole 172.
2 are slidably fitted together, and a hydraulic chamber 192 is defined by this lock piston 182. A lock pin 202 is integrally provided on the lock piston 182, and this lock pin 28
□ projects in response to the hydraulic pressure in the hydraulic chamber 19 □, and is retracted into the pin boss 4 by a return spring 212 provided in the small cylinder hole 17 □.

The hydraulic chamber 192 of the small cylinder hole 172 is communicated with an oil supply passage 23□ formed in the connecting rod 14 via an oil passage 222 formed on the piston pin P, and further communicated with the oil supply passage 23□ formed on the connecting rod 14.
32 passes through a main oil supply passage 24 □ formed in the crankshaft 15 and is communicated with a hydraulic pressure source 26 via a hydraulic pressure controller 25 . When the piston pin P rotates to the high compression ratio position, the oil passage 22
2 communicates with the hydraulic chamber 192 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 main oil supply passage 24 through the oil supply passage 232 and the oil passage 22□ to the hydraulic chamber 19 of the small cylinder hole 172.
supplied to

Note that 27 is an oil passage formed in the pin bosses 3 and 4.

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

CI) 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 switching device L1.
Side oil supply path 23. Please contact (.

Now piston pin P is the first. The 20th Tsuku device.

Assuming that neither L2 is locked, that is, the engine is operating with the piston pin P free, the piston 2 enters the suction stroke and its acceleration gradually decreases to zero. When the point is exceeded, the piston 2
Since negative acceleration is applied to the piston 2 until it reaches the bottom dead center, the piston 2 is braked during this period. However, since the piston 2 tries to move downward due to the inertia due to its mass, the piston pin P, which is in an unstable state, is affected by the inertia and moves to the low compression ratio side, that is, as shown in FIG. 2B, the crank portion 9 is moved downward. It rotates upward relative to the left and right journal parts 7 and 8. The oil passage 22° provided on the piston pin P at the suction path of the piston 2 is the oil supply passage 23. The 10th
Small cylinder hole 17 of the locking device L1. Hydraulic chamber 19. The low compression ratio side lock pin hole 13 communicates with the lock pin 20. of the lock piston 181. (Figure 6 (a)). Therefore, lock bin 20. receives the hydraulic pressure in the hydraulic chamber 191, protrudes outward, and fits into the lock pin hole 13. As a result, the piston pin P is locked and held at the low compression ratio position (Figs. 2A and 2B). As long as pressure oil is acting in the hydraulic chamber 191, the lock bin 20. Since the piston 2 is not pulled out from the lock pin hole 13, the piston 2 remains at the low compression ratio position and draws a motion curve C1 as shown by the dashed line in Figure 5, and the piston pin P is at the low position t. While held ＼ inhalation, compression,
The engine is operated under high load at a low compression ratio by repeating one stroke and exhaust stroke.

In addition, during the compression and explosion strokes, the internal pressure inside the cylinder 1 is high, so the piston 2 is urged downward by that pressure and tends to stay on the low compression ratio side.
As shown in →, lock pin 20. near the end of the compression and explosion strokes. There is a chance that it can fit into the lock bottle hole 13, and therefore, the timing of locking to the low compression ratio side by the 10th locking device is as shown in Figure 6 (a) and (b) ←→. three times near the end of each stroke.

In addition, in order to shift the engine from high-load operation to low-load operation, if the supply of pressure oil to the 10th engine is cut, the acceleration of piston 2 will be close to zero during the suction or exhaust stroke. When the force applied thereto becomes the minimum, the lock bin 20 of the tenth locking device L1 is released. The friction between the lock pin hole 13 and the lock pin hole 13 is reduced, and the lock pin 20
．． The piston pin P is pulled out of the lock pin hole 13 by the elastic force of the return spring 211 and sunk into the pin boss 4, and the piston pin P automatically becomes free.

[■] The high compression ratio operation hydraulic pressure controller 26 of the engine detects the low load operation of the engine and controls the hydraulic source 26 to supply oil to the 20th pump L2 side.
3. Connect to '2. Now piston pin P is the first
, 20th lock device, L2 are not locked, that is, when the engine is operating with the piston pin P free, when the engine enters the exhaust stroke and nears the end, cylinder 1 Since the internal pressure within the connecting rod 14 is close to atmospheric pressure, the piston 2 moves due to its own inertia.
The piston pin P
is rotated approximately 180 degrees to the high compression ratio side, that is, No. 4 A and B.
As shown in the figure, the crank portion 9 rotates downward relative to the left and right journal portions 7 and 8.

During this rotation process of the piston 2, the oil passage 22□ 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 is locked. The piston 18□ and the lock pin 20□ come to -i- (see Fig. 7). Therefore, the lock bin 202 is fitted into the lock bin hole 12, the piston pin P is locked, and the high compression ratio position (4th A, B
(Fig.) is maintained. As long as pressure oil is acting in the hydraulic chamber 192 of the 20th locking device L2, the lock bin 202
Since the piston 2 is not pulled out from the lock pin hole 12, the piston 2 is held at a high compression ratio position and draws a motion curve C2 as shown by the dotted line in Figure 5, and the piston pin P is held at a high position. Repeat the process of inhalation, compression, explosion and exhaust. 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 state shown in Fig. 7 (Iri~C・'), the piston 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 is released, the piston 2 is in the middle of the suction stroke or exhaust stroke when the acceleration is close to zero and the force acting thereon is the smallest. The lock bin 20□ sinks into 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 a motion curve C3 as shown by the solid line in Figure 5, and the piston pin P moves back and forth while fluctuating up and down in the high and low positions. varies depending on engine speed and load and is not necessarily constant.

As is clear from the above embodiments, according to the present invention, the piston is constituted by left and right journal portions at both ends, and a central crank portion which is eccentric from these journal portions and integral with them. Since the piston is locked in the high and low compression ratio positions, it is possible to securely keep the piston in the high and low compression ratio positions with a simple configuration, without having to incorporate a complicated hydraulic system inside the piston as in the past. It is possible to perform low-load operation at a high compression ratio and high-load operation at a low compression ratio, and it is possible to obtain an engine with significantly improved thermal efficiency and output performance.

[Brief explanation of the drawing]

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. 2A is a cross section taken along line flA-■A in Fig. 1. figure,
Figure 2B is a schematic diagram of Figure 2A, Figure 3 is a side view of the piston portion of the engine with the piston held at a high compression ratio position, and Figure 4A is a sectional view taken along the line A-PIA of Figure 3. , 4th B
The figure is a schematic diagram of Figure 4A, Figure 5 is a diagram showing the movement curve of the piston and the position of the piston pin in low and high compression ratio positions and free state, and Figure 6 is a diagram showing the low compression ratio lock. Schematic diagram showing the timing. FIG. 7 is a schematic diagram showing the high compression ratio lock timing. P... Piston pin, 1... Cylinder, 2... Piston, 3.4... Pin post, 7, 8... Left and right journal parts, 9... Crank part, 14... Connecting rod, 15... Crankshaft patent Applicant Honda Motor Co., Ltd. Figure 6 Figure 5 1 Rank shaft rotation umbrella February 14, 1959 1, Indication of case 1982 Patent application No. 173614 No.'°8''g''''s,,,,.Kowayo 1ya □3. Person making the amendment 4. Agent 〒105 Telephone Tokyo 434-4151 5. Date of amendment order January 11, 1980 (Shipping date: January 31, 1980) 6. Subject to amendment

Claims (1)

[Claims] In an internal combustion engine in which a piston pin that is mounted horizontally on a piston that is slidably fitted into a cylinder is connected to a connecting rod that is connected to a crankshaft, the piston pin is connected to the left and right journal portions at both ends, and from those journal portions. The left and right journal parts are rotatably supported by the left and right bin bosses of the piston, and the small end of the connecting rod is rotatably supported by the crank part. A tenth lock device and a twentieth lock are connected to the piston and the piston pin and selectively lock the piston pin in a low compression ratio position and a high compression ratio position as the piston reciprocates. A variable compression ratio device for an internal combustion engine, characterized in that the device is provided with a variable compression ratio device.