JPH048276Y2 - - 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 particularly relates to a hydraulic passage structure for switching the compression ratio.

[Conventional technology]

One mechanism 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 angularly displace the eccentric bearing to raise or lower the relative position of the piston to the connecting rod. There is a compression ratio variable mechanism that allows for variable settings (for example, Japanese Patent Application Laid-Open No. 58-172431
Publication No.).

The compression ratio variable mechanism using an eccentric bearing has a lock pin engagement hole in the eccentric bearing, a lock pin storage hole in the connecting rod, the lock pin is stored in the lock pin storage hole, and the lock pin is moved by applying hydraulic pressure to the lock pin. The lock pin is driven to move forward and backward in the direction of the engagement hole to engage and disengage the lock pin with the lock pin engagement hole.

A hydraulic passage for locking the lock pin and a hydraulic passage for unlocking the lock pin are connected to the lock pin storage hole, and during medium or light loads, oil is forced into the hydraulic passage for locking the lock pin and locks the eccentric bearing, resulting in a high compression ratio state. is beginning to appear. Furthermore, when the load is high, oil is forced into the lock pin unlocking hydraulic passage to unlock the eccentric bearing and create a low compression ratio state.

The lock pin locking hydraulic passage and the lock pin unlocking hydraulic passage are connected to two independent oil grooves formed on the circumference of the crank pin bearing portion of the connecting rod. These two oil grooves are connected to two independent oil grooves formed on the circumference of the bearing portion of the crank journal via oil holes in the crankshaft. The two oil grooves of this bearing are connected to a low compression ratio control hydraulic passage and a high compression ratio control hydraulic passage formed in the cylinder block, respectively. These hydraulic passages are connected via directional valves to a passage through which oil is pumped by an oil pump and a drain passage through which oil is returned to the oil pan.

In the hydraulic passage of the variable compression ratio mechanism configured in this way, the oil holes in the crankshaft connect each oil groove in the crank journal bearing and each oil groove in the crank pin bearing in a half rotation range of the crankshaft. It's starting to communicate. and,
The oil pumped into the oil groove of the crank journal bearing and the oil groove of the crank pin bearing also acts as lubricating oil for each bearing.

[Problem that the invention attempts to solve]

However, in conventional variable compression ratio mechanisms, when oil is being pumped into one of the high compression ratio hydraulic passage and the low compression ratio hydraulic passage for driving the lock pin, the other hydraulic passage is is exposed to the atmosphere through the drain passage, so only about half of the circumference of the crank journal and crank pin is always lubricated. In other words, among the oil grooves in the crank journal bearing part and the crank pin bearing part, the oil in one oil groove side is released through the drain passage, so the entire circumference of the crank pin and crank journal must be sufficiently lubricated at all times. I can't. Therefore, there was a risk that friction in each bearing portion would increase and seizure would occur at high rotations.

It is also possible to create a new dedicated lubrication passage to sufficiently lubricate the crank pin and crank journal, but in this case, the problem is that the passage configuration will become complicated and machining time will increase significantly. be.

The present invention has focused on the above problem and aims to provide a hydraulic passage for a variable compression ratio mechanism that has a simple passage configuration and can sufficiently lubricate the crank pin and crank journal.

[Means for solving problems]

The hydraulic passage of the variable compression ratio mechanism of the present invention that meets this purpose has an eccentric bearing rotatably interposed between the piston pin and the connecting rod, and the lock pin provided on the connecting rod side is connected to the crank journal. A variable compression ratio mechanism for an internal combustion engine, which locks or unlocks the rotation of the eccentric bearing by hydraulically driving it through a hydraulic passage provided in a bearing part and a crank pin bearing part, thereby varying the compression ratio. In the variable compression ratio mechanism, a drain discharge restriction means for restricting the flow of discharged oil is provided in the drain passage of the hydraulic passage of the variable compression ratio mechanism.

[Effect]

In the hydraulic passage of the variable compression ratio mechanism configured in this way, oil supplied to one hydraulic passage is supplied to the lock pin side via the hydraulic passage of the crank journal bearing and the crank pin bearing, and this oil pressure is The lock pin is driven by. As the lock pin is driven, the oil in the other hydraulic passage is discharged to the atmosphere through the crank journal bearing, the hydraulic passage in the crank pin bearing, and the drain passage, but in this case, the oil is not discharged to the drain passage. Since a drain discharge restriction means is provided to restrict the flow of oil, the pressure on the upstream side of the drain passage is increased. That is, in each bearing part, oil leaking from the hydraulic passage that is force-fed to the lock pin into the hydraulic passage that communicates with the drain passage is not drained as it is, but a part of it is supplied to the crank journal bearing part and the crank pin bearing part. .

Therefore, the crank journal bearing and the crank pin bearing are sufficiently lubricated by the pumped oil and the drained oil, reducing friction in each bearing and preventing seizure due to insufficient lubrication. Definitely prevented.

〔Example〕

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

FIRST EMBODIMENT FIGS. 1 to 3 show a first embodiment of the present invention, of which FIGS. 2 and 3 show a hydraulic passage in the vicinity of the locking mechanism of the eccentric bearing.

In FIGS. 2 and 3, a piston 1 is slidably inserted into a cylinder 2, and the reciprocating movement of the piston 1 is caused by the rotation of a crankshaft 5 via a piston pin 3 and a connecting rod 4. converted into exercise.

An eccentric bearing 6 whose inner and outer circumferences are mutually eccentric is interposed between the connecting rod 4 and the piston pin 3, and the compression ratio is changed according to the amount of rotation of the eccentric bearing 6. It's getting old. A lock pin engagement hole 7 extending in the radial direction is bored in the eccentric bearing 6, and a lock pin 8 is provided on the connecting rod 4 side. The lock pin 8 is slidably housed in the lock pin housing hole 9, and the lock pin 8 is slidably housed in the lock pin housing hole 9.
The lock pin is moved by the differential pressure between two hydraulic passages 10 and 11 formed therein for driving the lock pin. One hydraulic passage 10 is a hydraulic passage for locking the lock pin that drives the lock pin 8 in the direction of the eccentric bearing 6, and the other passage 11 is a hydraulic passage for unlocking the lock pin that drives the lock pin 8 in the direction away from the eccentric bearing 6. .

The lock pin locking hydraulic passage 10 and the lock pin unlocking hydraulic passage 11 communicate with mutually independent oil grooves 12 and 13 formed in the crank pin bearing portion 16 of the connecting rod 4, respectively. The oil grooves 12 and 13 are independent oil grooves 1 formed on the circumference of the crank journal bearing part 17 via an oil hole 14 formed in the crankshaft 5.
It is now possible to communicate with 8 and 19.

The oil hole 14 communicates the oil groove 12 and the oil groove 18 in the half rotation range of the crankshaft 5, and communicates the oil groove 13 and the oil groove 19 in the remaining half rotation range of the crankshaft 5. It's getting old.

FIG. 1 shows the hydraulic passage near the crank journal bearing and the directional control valve. In FIG. 1, 20 indicates an oil pan, and oil 21 is stored in the oil pan 20. As shown in FIG. Oil 21 in the oil pan 20 is pumped up by an oil pump 23 connected to the engine via an oil filter 22.
The oil 21 pumped up by the oil pump 23 is supplied to a valve train lubricating oil passage 24 and a variable compression ratio hydraulic passage 25, respectively.

Downstream of the variable compression ratio hydraulic passage 25, oil supplied from the oil pump 23 is passed through a high compression ratio control hydraulic passage 26 and a low compression ratio control hydraulic passage 27.
A directional switching valve 28 is provided for switching to either one of the two directions. The high compression ratio control hydraulic passage 26 is connected to the oil groove 18 as a hydraulic passage formed on the circumference of the crank journal bearing 17, and the low compression ratio control hydraulic passage 27 is connected to the crank journal bearing 17. It is connected to an oil groove 19 formed on the circumference of the journal bearing portion 17 .

The directional control valve 28 has a drain connected to the oil pan 20.
A drain passage 29 is connected thereto. That is, the drain passage 29 is communicated with either the high compression ratio control hydraulic passage 26 or the low compression ratio control hydraulic passage 27 by switching the directional switching valve 28. The drain passage 29 is provided with an orifice 30 as a drain discharge restricting means for restricting the flow of oil discharged to the oil pan side. In other words, the flow area of the drain passage 29 is locally reduced by the orifice 30.

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

Not shown when the engine is under light load
An actuation signal is output from the ECU (electronic control unit) to the directional switching valve 28, and the directional switching valve 28 is switched to one side. As a result, the oil pumped up from the oil pump 23 is forced into the oil groove 18 via the directional control valve 28 and the high compression ratio control hydraulic passage 26.
Further, pressure oil is intermittently sent from the oil groove 18 to the lock pin lock hydraulic passage 10 via the oil hole 14 of the crankshaft and the oil groove 12. Therefore, the lock pin 8 is engaged with the eccentric bearing 6, and a state of high compression ratio is achieved. In addition, the pressure oil in the hydraulic passage 11 for unlocking the lock pin is supplied to the oil groove 1.
3. The oil is discharged to the oil pan 20 via the oil hole 14, the oil groove 19, the low compression ratio control hydraulic passage 27, the directional switching valve 28, and the drain passage 29.

In this case, the drain passage 29 has an orifice 30.
Since the oil pan 20 is provided with an orifice 30, the amount of oil discharged is limited to a small amount.
The pressure of the oil upstream of is increased. Therefore, oil is also supplied to the crank journal and crank pin from the oil grooves 13 and 19 of the crank journal bearing part 17 and crank pin bearing part 16, which communicate with the drain passage 29, ensuring a sufficient amount of oil in each bearing part. be done.

When the engine is in a high load state, the directional control valve 28 is switched to the other direction, and the oil is transferred to the low compression ratio control hydraulic passage 27, the oil groove 19, and the oil hole 1 of the crankshaft.
4. The oil is fed under pressure through the oil groove 13 to the hydraulic passage 11 for unlocking the lock pin. Therefore, the engagement between the lock pin 8 and the eccentric bearing 6 is released, and a low compression ratio state appears.

In this case as well, as described above, the amount of oil discharged into the oil pan 20 is limited to a small amount by the orifice 30 of the drain passage 29, and the pressure of the oil upstream of the orifice 30 is increased. Therefore, the oil grooves 13 and 19 communicating with the drain passage 29
Oil is also supplied to the crank journal and crank pin.

In this way, the crank journal bearing portion 17 and the crank pin bearing portion 16 are supplied with both the oil pumped from the oil pump 23 and the oil drained from the oil pump 23, so that a sufficient amount of oil is secured in each bearing portion, and the friction is reduced. In addition to reducing this, seizing due to insufficient lubrication is also reliably prevented.

Second Embodiment FIG. 4 shows a hydraulic passage of a variable compression ratio mechanism according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in the configuration of the drain discharge restricting means, and other parts are similar to the first embodiment, so similar parts are designated by the same reference numerals as in the first embodiment. Explanation of the corresponding parts will be omitted, and only the different parts will be explained. The same applies to other embodiments described later.

In FIG. 4, the drain passage 29 is provided with a relief valve 40 as a drain discharge restricting means for restricting the flow of oil discharged to the oil pan 20 side. The relief valve 40 is connected to the drain passage 2
When the pressure inside 9 reaches a predetermined pressure, the oil in the passage is released to the oil pan 20.

In the second embodiment configured in this way,
Since the pressure of the drained oil is increased to the relief pressure of the relief valve 40, the amount of drained oil is limited to a small amount, and that amount is supplied to the crank journal bearing portion 17 and the crank pin bearing portion 16. Ru. Therefore, a sufficient amount of oil is ensured in each bearing, and friction between the crankshaft and each bearing is reduced.

Third Embodiment FIG. 5 shows a hydraulic passage of a variable compression ratio mechanism according to a third embodiment of the present invention.

In FIG. 5, the drain passage 29 is provided with a solenoid valve 50 as a drain discharge restricting means for restricting the flow of oil discharged to the oil pan 20 side. A solenoid valve 50 opens and closes the drain passage 29 depending on operating conditions. That is, the solenoid valve 50 is designed to close the drain passage 29, for example, in the high engine speed range, and the crank journal bearing 17 and the crank pin bearing 16 are sufficiently lubricated in the high speed range. ing.

In the third embodiment configured in this way,
For example, when the engine is running at low speed, the solenoid valve 50 is open, and the oil flowing through the drain passage 29 is discharged directly to the oil pan 20. When the engine rotates at high speed, the solenoid valve 50 is activated by a signal from the ECU (not shown), and the drain passage 29 is activated.
is closed. Therefore, the oil leaking from one oil groove to the other oil groove in each bearing part is not directly released to the oil pan 20 via the drain passage 29, and the lubrication of each bearing part is maintained well.

[Effect of idea]

As explained above, when using the hydraulic passage of the variable compression ratio mechanism of the present invention, the drain passage of the hydraulic passage is provided with a drain discharge restriction means for restricting the flow of discharged oil, so that the crank journal bearing Oil that leaks from the hydraulic passage that is force-fed to the lock pin into the hydraulic passage that communicates with the drain passage in the parts and crankpin bearings is no longer discharged as is through the drain passage, but is supplied to each bearing. This makes it possible to secure a sufficient amount of oil.

As a result, it is possible to reduce the friction between the crankshaft and the crank journal bearing portion and the crank pin bearing portion, and to reliably prevent seizure of each bearing portion due to insufficient lubrication.

In addition, by providing a drain discharge restriction means, there is no need to create a new lubrication passage.
It is possible to eliminate the complication of hydraulic passages.

[Brief explanation of the drawing]

1 is a system diagram of the hydraulic passage of the variable compression ratio mechanism according to the first embodiment of the present invention, FIG. 2 is a perspective view of the hydraulic passage near the crank journal bearing in FIG. 1, and FIG. A sectional view of the figure seen from another direction,
FIG. 4 is a system diagram of a hydraulic passage of a variable compression ratio mechanism according to a second embodiment of the present invention, and FIG. 5 is a system diagram of a hydraulic passage of a variable compression ratio mechanism according to a third embodiment of the present invention.
It is. 3... Piston pin, 4... Connecting rod, 5... Crankshaft, 6... Eccentric bearing, 8... Lock pin, 10... Hydraulic passage for lock pin locking, 11... Hydraulic passage for lock pin unlocking, 12 , 13, 18, 19...Oil groove (hydraulic passage), 14...Oil hole, 16...Crank pin bearing part, 17...Crank journal bearing part,
20...Oil pan, 23...Oil pump, 2
6... Hydraulic passage for high compression ratio control, 27... Hydraulic passage for low compression ratio control, 28... Directional switching valve, 29...
...Drain passage, 30... Orifice as drain discharge limiting means, 40... Relief valve as drain discharge limiting means, 50... Solenoid valve as drain discharge limiting means.

Claims (1)

[Claims for Utility Model Registration] (1) An eccentric bearing is rotatably interposed between the piston pin and the connecting rod, and the lock pin provided on the connecting rod side is connected to the crank journal bearing and the crank pin. In a variable compression ratio mechanism for an internal combustion engine, the compression ratio is varied by locking or unlocking the rotation of the eccentric bearing by hydraulically driving the eccentric bearing through a hydraulic passage provided in the bearing. A hydraulic passage of a variable compression ratio mechanism, characterized in that the drain passage of the hydraulic passage of the ratio mechanism is provided with a drain discharge restriction means for restricting the flow of discharged oil. (2) The hydraulic passage of the variable compression ratio mechanism according to claim 1, wherein the drain discharge limiting means is an orifice. (3) The hydraulic passage of the variable compression ratio mechanism according to claim 1, wherein the drain discharge limiting means is a relief valve. (4) The hydraulic passage of the variable compression ratio mechanism according to claim 1, wherein the drain discharge limiting means is a solenoid valve.