JPH0426674Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a variable compression ratio mechanism for an internal combustion engine using an eccentric bearing, and more particularly to a hydraulic passage for driving a lock pin for reliably switching the compression ratio.

[Conventional technology]

One of the mechanisms for varying the compression ratio in an internal combustion engine is to interpose an eccentric bearing between the piston pin and the connecting rod, and by angularly displacing the eccentric bearing, the relative position of the piston pin to the connecting rod can be changed up or down. There is a variable compression ratio mechanism that allows the setting to be varied (for example, JP-A-58-
Publication No. 91340).

The compression ratio variable mechanism using eccentric bearings is
As shown in Figures 4 to 4, eccentric bearing 1
A lock pin engagement hole 2 is provided in the connecting rod 3, a lock pin storage hole 4 is provided in the connecting rod 3, a lock pin 5 is stored in the lock pin storage hole 4, and the lock pin 5 is inserted into the engagement hole by applying hydraulic pressure to the lock pin 5. The lock pin 5 is engaged with and disengaged from the lock pin engagement hole 2 by being driven forward and backward in the direction.

The lock pin storage hole 4 includes a hydraulic passage 6 for locking the lock pin and a hydraulic passage 7 for unlocking the lock pin.
When the load is light, oil is forced into the lock pin lock hydraulic passage 6 to lock the eccentric bearing and create a high compression ratio state. In addition, when the load is high enough to cause knocking, oil is pumped into the lock pin unlocking hydraulic passage 7 to unlock the eccentric bearing 1, causing the eccentric bearing 1 to rotate and create a low compression ratio state. It's getting old.

A hydraulic passage 6 for locking the lock pin and a hydraulic passage 7 for unlocking the lock pin are formed on the circumference of the crank pin bearing portion 8 of the connecting rod 3.
It is connected to two independent oil grooves 9 and 10. These two oil grooves 9 and 10 are connected to two independent oil grooves 1 formed on the circumference of the crank journal bearing part 12 via an oil hole 11 in the crankshaft 17.
3 and 14. And oil groove 13,
14 is a hydraulic passage 15 for low compression ratio control and a hydraulic passage 1 for high compression ratio control formed in the cylinder block.
6, respectively.

In such a variable compression ratio mechanism, when the compression ratio is switched to the high compression ratio side, the oil pumped from the high compression ratio control hydraulic passage 16 to one oil groove 13 on the crank journal side is transferred to the crankshaft. It reaches the lock pin 5 side through the oil hole 11 of 17, one oil groove 9 on the crank pin bearing side, and the lock pin lock hydraulic passage 6, and the lock pin 5 is pushed toward the eccentric bearing 1 side by this oil pressure, and the eccentric bearing 1 is locked.

When the compression ratio is switched to the low compression ratio side, the oil pumped from the low compression ratio hydraulic passage 15 to the oil groove 14 on the circumference of the crank journal bearing 12 is transferred to the oil hole 11 of the crankshaft 17 and the crank pin. The lock pin 5 is reached through the oil groove 10 on the circumference of the bearing part 8 and the lock pin unlocking hydraulic passage 7, and the lock pin 5 is pushed back into the lock pin storage hole 4 by this oil pressure, and the lock of the eccentric bearing 1 is released. Ru.

[Problem that the invention attempts to solve]

However, in the configuration of the hydraulic passage described above, the oil groove for high compression ratio and the oil groove for low compression ratio provided in the crankshaft are arranged on the same circumference, and this oil groove As the engine speed increases, it is intermittently communicated with the high compression ratio oil groove and the low compression ratio oil groove, which are provided on the crankpin bearing and arranged on the same circumference, through the main oil hole. The communication time between the oil groove in the crank journal bearing and the oil groove in the crank pin bearing becomes short, resulting in insufficient oil pressure and oil on the connecting rod side, resulting in poor lock pin control and damage to the crank pin bearing. There was a risk of poor lubrication.

The present invention focuses on the above problem and provides a hydraulic passage structure that can extend the communication time between the oil hole in the crankshaft and the oil groove in the crank journal bearing regardless of the high or low engine speed.
The purpose is to ensure sufficient oil pressure and oil volume on the connecting rod side to improve both the reliability of lock pin control and the lubrication ability of the crank pin bearing.

[Means for solving problems]

The hydraulic passage of the variable compression ratio mechanism of the present invention that meets this purpose includes an eccentric bearing rotatably interposed between the connecting rod and the piston pin.
In a variable compression ratio mechanism for an internal combustion engine, the compression ratio is switched between a high compression ratio and a low compression ratio by locking and unlocking the compression ratio using a hydraulically driven lock pin provided on the connecting rod side. A first high compression ratio oil groove and a first low compression ratio oil groove formed in the connecting rod and connected to a hydraulic passage for driving the lock pin are arranged on the circumference of the bearing portion of the crankshaft. separated in the axial direction of the
On the circumference of the crank journal bearing part, a second height is connected to the high compression ratio control hydraulic passage and communicates with the first high compression ratio oil groove via the high compression ratio oil hole in the crankshaft. a compression ratio oil groove, and a second low compression ratio that is connected to the low compression ratio control hydraulic passage and communicates with the first low compression ratio oil groove via a low compression ratio oil hole in the crankshaft. The second oil groove for high compression ratio and the second oil groove for low compression ratio are arranged on the top dead center side of the piston. The length of each of the second oil grooves is half of the length on the circumference of the crank journal bearing part, and the crank journal is provided with:
Two cross holes are provided that pass through the axis of the crankshaft and both ends open toward the crank journal bearing side, one end of one cross hole is connected to the opening of the high compression ratio oil hole, and the other end is connected to the opening of the high compression ratio oil hole. One end of the other cross hole is connected to the opening of the low compression ratio oil hole, and the other end is communicated with the second high compression ratio oil groove. It consists of what is possible.

[Effect]

In the hydraulic passage of the variable compression ratio mechanism configured in this way, when the compression ratio is high, oil is sent under pressure from the high compression ratio control hydraulic passage to the second high compression ratio oil groove, and this oil is pumped into the crankshaft. The oil is fed under pressure to the first high compression ratio oil groove on the connecting rod side through the high compression ratio oil hole. When the compression ratio is low, oil is pumped from the low compression ratio control hydraulic passage to the first low compression ratio oil groove, and this oil passes through the low compression ratio oil hole in the crankshaft to the first low compression ratio oil groove. The oil is fed under pressure to the low compression ratio oil groove No. 1.

In this case, the first high compression ratio oil groove and the first low compression ratio oil groove on the crank pin bearing side are separated, and the second high compression ratio oil groove on the crank journal bearing side is separated. Since the second low compression ratio oil groove is separated, it is possible to constantly communicate the second high compression ratio oil groove with the high compression ratio oil hole in the crankshaft, and the second low compression ratio oil groove is separated. It becomes possible to constantly communicate the low compression ratio oil groove and the low compression ratio oil hole.

Therefore, oil can be continuously pumped to the connecting rod, maintaining good lubrication of the crank pin bearing, and increasing the reliability of lock pin control.

In addition, since two cross holes are provided in the crank journal, the length of the second high compression ratio oil groove and the second low compression ratio oil groove is half the circumferential length of the crank journal bearing. It can be done. Therefore, compared to the case where oil grooves are provided all around the circumference, a larger pressure receiving area for the explosive load can be ensured in the crank journal bearing portion, and the strength against the explosive load is increased.

Furthermore, since the second high compression ratio oil groove and the second low compression ratio oil groove are located on the top dead center side of the piston, which is not directly exposed to explosive loads, the crank journal bearing is protected against explosive loads. This makes it possible to create a structure that is advantageous in terms of strength. That is, the maximum explosive load does not act on the top dead center side of the piston where the pressure receiving area is small, and this also increases the strength of the crank journal bearing against the explosive load.

〔Example〕

Hereinafter, preferred embodiments of the variable compression ratio mechanism hydraulic passage according to the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a hydraulic passage of a variable compression ratio mechanism according to a first embodiment of the present invention. In the figure, a piston 21 is slidably inserted into a cylinder 22, and the reciprocating motion of the piston 21 is converted into rotational motion of a crankshaft 25 via a piston pin 23 and a connecting rod 24.

Connecting rod 24 and piston pin 23
An eccentric bearing 26 whose inner and outer circumferences are mutually eccentric is interposed between the eccentric bearing 2 and
The compression ratio is changed according to the amount of rotation of 6. A lock pin engagement hole 27 extending in the radial direction is bored in the eccentric bearing 26, and a lock pin 28 is provided on the connecting rod 24 side. The lock pin 28 is slidably housed in a lock pin housing hole 29, and is moved by the differential pressure between two hydraulic passages 30 and 31 formed in the connecting rod 24 for driving the lock pin. One hydraulic passage 30 is a hydraulic passage for a lock pin lock that drives the lock pin 28 toward the eccentric bearing 26, and the other passage 31
is a hydraulic passage for unlocking the lock pin that drives the lock pin 28 in a direction away from the eccentric bearing 26.

The lock pin lock hydraulic passage 30 communicates with a first high compression ratio oil groove 32 formed on the circumference of the crank pin bearing portion 35 of the connecting rod 24. Hydraulic passage 3 for lock pin unlocking
1 communicates with a first low compression ratio oil groove 33 that is similarly formed on the circumference of the crank pin bearing portion 35 . The first high compression ratio oil groove 32 and the first low compression ratio oil groove 33 are arranged separately and independently in the axial direction of the crankshaft 25. The length of the first high compression ratio oil groove 32 is half the circumferential length of the crank journal bearing 35, and the length of the first low compression ratio oil groove 33 is This is the remaining half of the length other than the length of the high compression ratio oil groove 32.

The first high compression ratio oil groove 32 is connected to the second high compression ratio oil formed on the circumference of the crank journal bearing part 36 via the high compression ratio oil hole 34 formed in the crankshaft 25. It can communicate with the groove 37. The first low compression ratio oil groove 33 is similarly formed in the crankshaft 25 and passes through the low compression ratio oil hole 38 to a second low compression ratio oil groove formed on the circumference of the crank journal bearing part 36. It can communicate with the oil groove 39.

The second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 are arranged separately and independently in the axial direction of the crankshaft 25. The lengths of the second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 are as follows:
It forms one half of the circumference of the crank journal shaft portion 36, and these portions are arranged at the same position based on the crank angle.

Crank journal 4 of crankshaft 25
0 is provided with cross holes 41 and 42 passing through the axis of the crankshaft 25. cross hole 4
Reference numerals 1 and 42 denote holes that pass through the crank journal 40, and both ends thereof are opened toward the crank journal bearing portion 36, respectively. cross hole 41
One end 41a is connected to one opening 34a of the high compression ratio oil hole 34. The other end 41b of the cross hole 41 is disposed at a position shifted by 180 degrees in crank angle from the one end 41a of the cross hole 41, and can communicate with the second high compression ratio oil groove 37. One end 42a of the cross hole 42 is a low compression ratio oil hole 38.
The opening 38a is connected to one of the openings 38a. The other end 42b of the cross hole 42 is disposed at a position shifted by 180 degrees in terms of crank angle from one end of the cross hole 42, and can communicate with the second low compression ratio oil groove 39.

The high compression ratio oil hole 34 communicates the first high compression ratio oil groove 32 and the second high compression ratio oil groove 37 in the half rotation range of the crankshaft 25, and the low compression ratio oil hole 38 connects the first low compression ratio oil groove 33 and the second low compression ratio oil groove 39 to the crankshaft 2.
It is designed to communicate in the remaining half rotation range of the engine.

Although the second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 are formed only half the circumference of the crank journal bearing portion 35 as described above,
The cross holes 41 and 42 allow the second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 to connect to the high compression ratio oil hole 34 and the low compression ratio oil in the entire rotation range of the crankshaft 25. The holes 38 can be communicated with each other.

In this embodiment, the second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 are arranged on the piston top dead center side of the crank journal bearing portion 36, as shown in FIG. has been done.

The second high compression ratio oil groove 37 is connected to a high compression ratio control hydraulic passage 44 formed in the cylinder block 43.
The second low compression ratio oil groove 39 is similarly connected to a low compression ratio control hydraulic passage 45 formed in the cylinder lock 43. Hydraulic passage 44 for high compression ratio control, hydraulic passage 4 for low compression ratio control
5, oil pumped up from an oil pan (not shown) by an oil pump (not shown) and set at a predetermined pressure is pumped through a switching valve 46.

Next, the operation of this embodiment will be explained.

Not shown when the engine is under light load
An activation signal is output from the ECU (electronic control unit) to the switching valve 46, and the switching valve 46 is switched to one side.
As a result, the oil pumped from the oil pan is transferred to the switching valve 46 and the high compression ratio control hydraulic passage 44.
is fed under pressure to the second high compression ratio oil groove 37 through
Further, oil is intermittently sent from the second high compression ratio oil groove 37 to the lock pin lock hydraulic passage 30 via the high compression ratio oil hole 34 of the crankshaft and the first high compression ratio oil groove 32. It will be done. As a result, the lock pin 28 is pushed out toward the eccentric bearing 26, and the eccentric bearing 26 is pushed out toward the lock pin 28.
Locked by. Therefore, the relative position of the piston 21 with respect to the connecting rod 24 is changed, and a high compression ratio state is created. In this case, the high compression ratio oil hole 34 and the second high compression ratio oil groove 37 can communicate with each other in the entire rotation range of the crankshaft 25, so that oil pressure is always applied to the high compression ratio oil hole 34. The lubrication of the crank pin bearing portion 35 is maintained well, and the hydraulic pressure acting on the lock pin 28 is also sufficient. The oil in the lock pin unlocking hydraulic passage 31 is supplied to the first low compression ratio oil groove 33, the low compression ratio oil hole 38, the second low compression ratio oil groove 39, and the low compression ratio control hydraulic passage 45. , and is returned to the oil pan (not shown) via the switching valve 46.

When the engine is under high load, the switching valve 43 is switched to the other side, and the oil pumped up from the oil pan is transferred to the second low compression ratio control via the switching valve 46 and the low compression ratio control hydraulic passage 45. The oil is fed under pressure to the oil groove 39, and the oil is further transferred to the second low compression ratio oil groove 3.
9. Low compression ratio oil hole 3 in the crankshaft 25
8. The oil is intermittently sent to the lock pin unlocking hydraulic passage 31 via the first low compression ratio oil groove 33. This hydraulic pressure disengages the lock pin 26 from the lock pin engagement hole 27 of the eccentric bearing 28, and the eccentric bearing 28 is unlocked. Therefore, the eccentric bearing 28 becomes rotatable, and the relative position of the piston 21 with respect to the connecting rod 24 changes, thereby creating a low compression ratio state.

Also in this case, the low compression ratio oil hole 38 and the second low compression ratio oil groove 39 are in communication throughout the entire rotation range of the crankshaft 25, so the low compression ratio oil hole 38
Oil pressure is always applied to the crank pin bearing part 35.
lubrication is maintained well, and sufficient hydraulic pressure acts on the lock pin 28 as well.

Here, since the two cross holes 41 and 42 are provided in the crank journal 40, the length of the second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 is determined by the length of the crank journal bearing. It can be half of the length on the circumference of 36. Therefore, the pressure receiving area of the crank journal bearing part 36 against the explosive load can be secured larger than in the case where an oil groove is provided all around the crank journal bearing part 36, and the strength against the explosive load is increased.

In addition, the second high compression ratio oil groove 37 and the second low compression ratio oil groove 39 are arranged on the top dead center side of the piston 21, which is not directly exposed to the explosion load.
Furthermore, the strength of the crank journal bearing portion 36 against explosive loads can be increased.

[Effect of idea]

According to the hydraulic passage of the variable compression ratio mechanism of the present invention,
The following effects can be obtained.

(1) On the circumference of the crank pin bearing, install a first high compression ratio oil groove and a first low compression ratio oil groove connected to the hydraulic passage that drives the lock pin in the direction of the axis of the crankshaft. The first high compression ratio oil groove is connected to the high compression ratio control hydraulic passage on the circumference of the crank journal bearing, and communicates with the first high compression ratio oil groove through the high compression ratio oil hole in the crankshaft. A second high compression ratio oil groove and a second oil groove connected to the low compression ratio control hydraulic passage and communicating with the first low compression ratio oil groove via a low compression ratio oil hole in the crankshaft. Since the oil groove for low compression ratios is separated from the oil groove in the axial direction of the crankshaft, intermittent oil pumping at the crank journal bearing is eliminated, and the In both cases, oil can be continuously pumped to the crankpin bearing at all times.

Therefore, the amount of oil pumped to the connecting rod side is increased and the pressure is also increased, making it possible to improve both the reliability of lock pin control and the lubricating ability of the crank pin bearing.

(2) Arranging the second high compression ratio oil groove and the second low compression ratio oil groove on the piston top dead center side,
Its length is half of the circumferential length of the crank journal bearing, and two cross holes are provided in the crank journal, each passing through the axis of the crankshaft and opening at both ends toward the crank journal bearing. Connect one end of the hole to the opening of the oil hole for high compression ratio, and connect the other end to the second
One end of the other cross hole was connected to the opening of the low compression ratio oil hole, and the other end was connected to the second low compression ratio oil groove. A larger pressure-receiving area for the explosive load of the crank journal bearing can be secured than in the case where an oil groove is provided all around the crank journal bearing.

In addition, the second high compression ratio oil groove and the second low compression ratio oil groove are located on the top dead center side of the piston, which is not directly exposed to explosive loads, so that the crank journal bearing is protected against explosive loads. The structure can be advantageous in terms of strength.

[Brief explanation of the drawing]

FIG. 1 is a transparent perspective view of a hydraulic passage of a variable compression ratio mechanism according to an embodiment of the present invention, FIG. 2 is a sectional view showing an example of a conventional variable compression ratio mechanism, and FIG. FIG. 4 is a sectional view taken along the line, and FIG. 4 is a perspective view of the hydraulic passage near the crankshaft in FIG. 2. 21... Piston, 23... Piston pin, 2
4... Connecting rod, 25... Crankshaft, 26... Eccentric bearing, 28... Lock pin, 30... Hydraulic passage for lock pin locking, 31... Hydraulic passage for lock pin unlocking,
32...First high compression ratio oil groove, 33...Second low compression ratio oil groove, 34...High compression ratio oil hole, 35
...Crank pin bearing part, 36...Crank journal bearing part, 37, 51...Second high compression ratio oil groove, 38...Low compression ratio oil hole, 39, 52...
2nd oil groove for low compression ratio, 41, 42...Cross hole, 46...Switching valve, 44...Hydraulic passage for high compression ratio control, 45...Hydraulic passage for low compression ratio control.

Claims (1)

[Scope of utility model registration request] An eccentric bearing rotatably interposed between the connecting rod and the piston pin is locked and unlocked by a hydraulically driven locking pin provided on the connecting rod side to set the compression ratio to a high compression ratio or a low compression ratio. In the variable compression ratio mechanism for an internal combustion engine, a first hydraulic passage formed in the connecting rod and connected to a hydraulic passage for driving the lock pin is provided on the periphery of the crank pin bearing portion of the connecting rod. A first oil groove for high compression ratio and a first oil groove for low compression ratio are provided separately in the axial direction of the crankshaft, and are connected to a hydraulic passage for high compression ratio control on the circumference of the crank journal bearing part. a second high compression ratio oil groove that can communicate with the first high compression ratio oil groove via a high compression ratio oil hole in the crankshaft; and a second high compression ratio oil groove that is connected to the low compression ratio control hydraulic passage. A second low compression ratio oil groove that can communicate with the first low compression ratio oil groove through a low compression ratio oil hole in the crankshaft is provided separated in the axial direction of the crankshaft, and When the second high compression ratio oil groove and the second low compression ratio oil groove are arranged on the top dead center side of the piston, the length of each second oil groove is set to the circumference of the crank journal bearing. Two cross holes are provided in the crank journal that pass through the axis of the crankshaft and both ends open toward the crank journal bearing, and one end of the cross hole is connected to the high compression ratio oil. one end of the other cross hole is connected to the opening of the low compression ratio oil hole, and the other end thereof is connected to the opening of the low compression ratio oil groove, and the other end thereof is connected to the opening of the low compression ratio oil groove. A hydraulic passage of a variable compression ratio mechanism, characterized in that it can communicate with the second low compression ratio oil groove.