JPS6148615B2 - - Google Patents

Abstract

PURPOSE:To smoothly turn an eccentric bearing and improve its reliability and durability, by providing a different lubricating oil passage communicated to an oil passage for a slidable lock pin provided between a connecting rod and the eccentric bearing. CONSTITUTION:Under a condition in which an eccentric bearing 5 and connecting rod 4 are not fixed by a lock pin 7, a piston 1 is in a low compression state, reversely under a condition fixed with the both 5, 4 by the pin 7, the piston becomes a high compression state. In such a variable compression mechanism, lubricating oil passages 10, 11 are connected in the rod 4 in addition to a normally provided lock pin driving oil passage 8. That is, the passage 10 is communicated to a peripheral sliding part 12 of the bearing 5 from a throttle part 9 and the passage 11 is communicated to an internal peripheral sliding part 13 from the part 12. While a groove 14 is formed circumferentially along the periphery of the bearing 5 in a small-end of the rod 4, and this groove 14 is connected to an oil filler port 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable compression ratio mechanism for an internal combustion engine in which an eccentric bearing is interposed between a connecting rod and a piston pin to change the compression ratio of the engine. In particular, it relates to a lubricating device for an eccentric bearing, which is a main component of a variable compression ratio mechanism.

In order to improve the engine's fuel economy, emissions, output performance, and low-temperature startability, it is possible to change the compression ratio according to operating conditions by lowering the compression ratio at full load and increasing it at partial load. It is valid.

For this purpose, a variable compression ratio mechanism was first developed in which an eccentric bearing is interposed between the connecting rod and the piston pin, and the rotation of the eccentric bearing changes the relative position of the piston to the connecting rod, thereby making the compression ratio variable. Proposed.

For example, Figure 1 shows a typical example of a variable compression ratio mechanism previously proposed (Japanese Patent Application No. 56-136298 (Japanese Unexamined Patent Publication No. 58-38344)), in which connecting rod 1' and eccentric bearing A lock pin fixing chamber 3' is formed across the lock pin fixing chamber 3', and a lock pin 4' is slidably inserted into the lock pin fixing chamber 3'.
An oil passage 5' is connected to the lock pin fixing chamber 3', and this mechanism applies and releases hydraulic pressure to the lock pin 4' through the oil passage 5', thereby causing rotation of the eccentric bearing 2'. can be fixed or set free, making the compression ratio variable.

Furthermore, Figure 2 shows another typical example of the previously proposed variable compression ratio mechanism (patent application filed on November 26, 1982 (Japanese Patent Application Laid-Open No. 1983-91340), the title of the invention is " Two oil passages 5' and 6' are connected to the lock pin fixing chamber 3' of the previous example, and the lock pin 4' can be driven hydraulically in both the vertical and vertical directions. 4' is made more reliable without relying solely on inertial force, and variable operation of the compression ratio is made more reliable.

However, in the variable compression ratio mechanism using an eccentric bearing as described above, the eccentric bearing is lubricated by natural supply from the oil filler port 7' provided at the upper part of the small end of the connecting rod 1'. In the above mechanism where the movement of the eccentric bearing 2' is the key, lubrication using only this method would result in a small amount of oil and the movement of the eccentric bearing 2' would become irregular. There has been a problem that switching between high and low compression ratios may become impossible, or in severe cases, the eccentric bearing 2' may seize.

In order to solve the above problems in variable compression ratio mechanisms using eccentric bearings, the present invention provides lubrication of eccentric bearings that allows smooth and reliable movement of the eccentric bearings and prevents seizure of the eccentric bearings. The purpose is to provide equipment.

In order to achieve this objective, in the variable compression ratio mechanism lubricating device of the present invention, a part of the lock pin driving oil passage formed in the connecting rod preferably has a cross-sectional area smaller than the passage cross-sectional area. A lubricating oil passage is provided and communicated with the sliding portion of the eccentric bearing, so that the lubricating oil can be guided to the sliding portion on the inner and outer periphery of the eccentric bearing via this oil passage. . By supplying oil through this lubricating oil passage, lubrication is much smoother and more reliable than the conventional lubrication from only the oil filler port at the upper end of the small end.

Preferred embodiments of the present invention will be described below with reference to the drawings.

3 and 4 show a first embodiment of the invention. In the figure, 1 is a piston, 2 is a cylinder block, 3 is a piston pin, and 4 is a connecting rod. Between the piston pin 3 and the connecting rod 4, an eccentric bearing 5 made of an eccentric cylinder is rotatable. It has been intervened. A lock pin fixing chamber 6 is provided across the eccentric bearing 5 and the connecting rod 4, and a lock pin 7 is slidably inserted into the lock pin fixing chamber 6. Inside the connecting rod 4, an oil passage 8 for driving the lock pin extends from the big end toward the small end, and the oil passage 8 communicates with the lock pin fixing chamber 6. The connection part 9 of the oil passage 8 to the lock pin fixing chamber 6 is constricted.
The lock pin 7 is prevented from falling into the oil passage 8. These oil passages 8 and 9 form an oil passage for driving the lock pin 7.

A separate oil passage 1 is provided for the oil passage for driving the lock pin.
0 and 11 are connected, and the oil passage communicates with the sliding parts 12 and 13 of the eccentric bearing 5. The oil passage 10 extends, for example, from the throttle part 9 to the outer peripheral sliding part 12 of the eccentric bearing 5, and the oil passage 11
extends from the outer circumferential sliding portion 12 to the inner circumferential sliding portion 13 of the eccentric bearing 5. These oil passages 10,
Reference numeral 11 guides oil from the drive oil passages 8 and 9 to the sliding parts 12 and 13 of the eccentric bearing 5, forming a lubricating oil passage. Lubricating oil passages 10, 11
has a smaller cross-sectional area than the drive oil passages 8 and 9, and a larger amount of oil flows through the oil passages 10 and 11 than the drive oil passages 8 and 9.
The lock pin 7 is designed so that it does not flow into the air and obstruct the driving of the lock pin 7. Note that a groove 14 is formed circumferentially in the small end of the connecting rod 4 along the outer periphery of the eccentric bearing 5, and this groove 14 is also connected to an oil inlet 15.

The lower end of the oil passage 8 is connected to a semicircular groove 17 formed along the outer circumference of the crank pin 16 of the connecting rod 4 big end.
are connected to two mutually independent semicircular grooves 20 and 21 formed along the outer periphery of the crank journal 19 by an oil passage 18 in the crankshaft. The two independent grooves 20 and 21 are respectively connected to two mutually independent main passages formed in the cylinder block, namely a high compression ratio main passage 22 and a low compression ratio main passage 23. Pressure oil is supplied under pressure from the oil pan via the oil pump, and is controlled by a switching valve according to the operating conditions of the engine.
It is supplied to either the high compression ratio main passage 22 or the low compression ratio main passage 23. Reference numeral 24 denotes an oil jet port to the piston 1, which can be connected to the low compression ratio main passage 23 via the oil passage 18.

Next, the operation of the apparatus of the first embodiment will be explained.

First, when the eccentric bearing 5 is not fixed, the balance between the explosion pressure and inertia force applied to the piston 1 causes the piston 1 to operate as shown by the broken line in FIG.
When is fixed, it operates as shown by the solid line in FIG. 5, resulting in a high compression ratio state. That is, the piston 1 is fixed or free to rotate due to the eccentric bearing 5.
Two positions are possible for the connecting rod 4: high compression ratio and low compression ratio.

Now, when it is desired to have a high compression ratio state such as during partial load operation, by switching the switching valve to the high compression ratio main passage 22 side, high pressure oil is transferred to the oil passages 20, 18. . 6, the rotation of the eccentric bearing 5 is fixed, and a state of high compression ratio is obtained.

In a high compression ratio state, the sliding portion of the eccentric bearing 5 is the sliding surface of the piston pin 3 and the inner peripheral surface of the eccentric bearing 5, but in this case, the oil passage 10,
11 are in a straight line as shown in FIG. 3, sufficient oil is supplied to the sliding surface on the inner peripheral side, and sufficient lubrication is achieved.

Furthermore, when a low compression ratio state is desired such as during full load operation, the pressure of the pressure oil is applied to the low compression ratio main passage 23 by switching the switching valve, and the oil is transferred to the oil spout 24. No pressure is applied to the lock pin 7, and the lock pin 7 comes out of the lock pin fixing chamber 6 formed on the eccentric bearing 5 side by inertia force, and the eccentric bearing 5 becomes free to rotate, and the piston 1 By operating as shown by the broken line in FIG. 5, the low compression ratio state shown in FIG. 4 is obtained. In this case, the sliding parts of the eccentric bearing 5 are the inner and outer peripheries of the eccentric bearing 5, but after the oil applied to the inner wall of the piston 1 from the oil spout 24 cools the piston 1, the oil is poured from the oil inlet 15. The oil enters the groove 14 to lubricate the outer circumference of the eccentric bearing 5, and further lubricates the inner circumference of the eccentric bearing 5 through the oil passage 11 and the hole in the lock pin fixing chamber 6. This allows the eccentric bearing 5 to move smoothly and reliably.

6 and 7 show a second embodiment of the invention. This embodiment has the same structure and operation as the first embodiment, except that the lubricating oil passage is provided inside the lock pin itself in the longitudinal direction. The same reference numerals as in FIGS. 3 and 4 are given. In the second embodiment, 5 is an eccentric bearing, 6 is a lock pin fixing chamber, 7 is a lock pin, the through hole inside the lock pin 7 is constituted by a lubricating oil passage 25, and the oil passages 10 and 11 of the first embodiment are combined. corresponds to

Next, the operation in the second embodiment will be explained.

FIG. 6 shows the lubrication of the eccentric bearing 5 in a high compression ratio state. Oil groove 17 to maintain high compression ratio
The oil supplied to the lock pin fixing chamber 6 is supplied to the lock pin fixing chamber 6 through the oil passage 8, and the lock pin 7 is pushed into the lock pin fixing chamber 6 of the eccentric bearing 5, thereby fixing the rotation of the eccentric bearing 5. Further, excess oil is used to lubricate the sliding surface inside the eccentric bearing 5 via a lubricating oil passage 25 inside the lock pin 7. Here, an oil groove may be provided on the inner surface of the eccentric bearing 5 or the outer surface of the piston pin 3 to further promote lubrication, or the oil groove may be combined with the oil groove 14 to cool the piston via the oil supply port 15.

Although FIG. 7 shows the case of a low compression ratio, the oil from the oil spout 24 is cooled down to the oil inlet 1 after the piston has cooled.
The eccentric bearing 5 is lubricated via 5.

8 and 9 show a third embodiment of the invention. In this embodiment, there are two oil passages in the connecting rod 4 that drive the lock pin 7.
Systems 8 and 26 are provided, and the lock pin 7 has a flange 7a to receive pressure from above to below. In the lock pin fixing chamber 6, a portion 27 corresponding to the upper part of the flange 7a functions as an operating chamber for releasing the fixation of the lock pin, and an oil passage 26 communicates with this portion 27. The lubricating oil passages 10 and 11 communicate with this oil passage 26. 28 is an oil groove for high compression ratio provided in the crank pin bearing, and 29 is an oil groove for low compression ratio, which are independent from each other and connected to oil passages 8 and 26, respectively. The oil grooves 28 and 29 are connected to the oil grooves 20 and 2 of the crank journal bearing, respectively, through an oil passage 18 provided in the crankshaft.
1, and further connected to a high compression ratio main passage 22 and a low compression ratio main passage 23. Pressure oil can be switched to both main passages 22 and 23 using a switching valve according to engine operating conditions. The rest of the structure is similar to the first embodiment, so similar parts are given the same reference numerals as in FIGS. 3 and 4.

The operation of the third embodiment is as follows. That is, at partial load, the switching valve switches to the side that applies hydraulic pressure to the main passage 22 for high compression ratio, and a part of the pressure oil flows from the oil spout 24 to the piston via the oil groove 20, oil passage 18, and oil groove 28. 1 and the rest enters the lock pin fixing chamber 6 through the oil passage 8.
Drive the lock pin 7 to push the lock pin 7 into the lock pin fixing chamber 6 in the eccentric bearing 5,
As shown in FIG. 8, the eccentric bearing 5 is fixed in a high compression ratio state. After the oil ejected from the oil spout 24 cools the piston 1, a part of it enters the oil inlet 15 and the outer circumferential groove 14 of the outer circumference 5 of the eccentric bearing to lubricate the outer circumferential sliding surface.

Also, at full load, the switching valve switches to the low compression ratio main passage 23 side, and the pressure oil is transferred to the oil groove 21 and oil passage 1.
8. Lock pin 7 via oil groove 29 and oil passage 26
Push downward to release the eccentric bearing 5 from locking the rotation as shown in FIG. This results in a low compression ratio condition. In this case, excess oil in the oil passage 26 is supplied to the outer periphery of the eccentric bearing 5 via the lubricating oil passage 10, and further via the oil groove 14.
The oil is also supplied to the inner peripheral sliding portion of the eccentric bearing 5 through the oil passage 11 and the hole in the lock pin fixing chamber of the eccentric bearing 5. This lubricates the eccentric bearing 5.

As described above, the eccentric bearing lubrication device for the variable compression ratio mechanism of the present invention further includes a lubrication oil passage in addition to the oil passage for driving the lock pin, and lubricates the inner and outer sliding parts of the eccentric bearing. Therefore, according to the present invention, regular movement of the eccentric bearing can be obtained and seizing of the eccentric bearing can also be prevented. As a result, a variable compression ratio mechanism with excellent reliability and durability can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the operating system of the previously proposed variable compression ratio mechanism, FIG. 2 is a cross-sectional view showing the operating system of the previously proposed variable compression ratio mechanism according to another example, and FIG. 4 is a cross-sectional view of the mechanism shown in FIG. 3 in a state where the eccentric bearing is free to rotate; FIG. 6 is a diagram of the operating state of the piston, FIG. 6 is a cross-sectional view of the eccentric bearing rotationally fixed state showing the operating system of the variable compression ratio mechanism according to the second embodiment of the present invention, and FIG. 7 is the eccentric bearing of the mechanism of FIG. 6. 8 is a sectional view of the eccentric bearing in the rotationally fixed state showing the operating system of the variable compression ratio mechanism according to the third embodiment of the present invention; FIG. 9 is the eccentric bearing of the mechanism shown in FIG. 8. FIG. 3 is a cross-sectional view in a rotationally free state. 1... Piston, 3... Piston pin, 4...
Connecting rod, 5... Eccentric bearing,
6...Lock pin fixing chamber, 7...Lock pin,
8, 26...Lock pin driving oil passage, 10, 1
1, 25...Lubricating oil passage, 15...Oil filler port,
24...Oil spout.

Claims (1)

[Claims] 1. An eccentric bearing is interposed between the connecting rod and the piston pin, a lock pin fixing chamber is formed by straddling the connecting rod and the eccentric bearing, and the lock pin is slidably inserted into the lock pin fixing chamber. In the variable compression ratio mechanism, an oil passage for driving the lock pin is connected to the lock pin fixing chamber, and hydraulic pressure is applied to the lock pin via the oil passage to operate the lock pin to change the compression ratio of the engine. Providing the oil passage with another oil passage for lubrication communicating with the oil passage,
An eccentric bearing lubrication device for a variable compression ratio mechanism, characterized in that the oil passage for lubrication faces the sliding part of the eccentric bearing.