JPH0338425Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a variable compression ratio mechanism for a reciprocating piston internal combustion engine, and particularly to a variable compression ratio mechanism having an oil passage for switching the compression ratio.

[Conventional technology]

2. Description of the Related Art Variable compression ratio mechanisms for reciprocating piston internal combustion engines have been known in the art, which vary the compression ratio according to the operating conditions of the engine to improve output and fuel efficiency as well as to prevent the occurrence of noise. A conventionally known variable compression ratio mechanism of this type is one in which an eccentric bearing is interposed in the shaft support between the piston and connecting rod, and a hydraulically actuated lock pin provided inside the connecting rod moves in and out of the eccentric bearing. It has been proposed that the compression ratio of this eccentric bearing can be changed to two levels: a position where it is locked to the connecting rod (high compression ratio) and a position where it can rotate freely (low compression ratio).
58-172431). In this variable compression ratio mechanism, in order to apply hydraulic pressure to the lock pin, oil is supplied through oil passages for switching the compression ratio formed inside the crankshaft and the connecting rod.

However, the connection of the oil passages in the journal portion and the crank pin portion of the crankshaft requires special consideration because they are rotating parts. In other words, a main bearing is installed in the journal part of the crankshaft on the side of the cylinder block, which is the shaft support, and a connecting rod bearing is installed in the bearing hole of the large end of the connecting rod, which is the shaft support in the crank pin part. In these bearings, a circumferential oil passage for oil switching is formed in the axial center of the bearing, extending almost all the way around the circumference, and the crankshaft is It is connected to the internal oil passage. However, oil from the oil passage in the circumferential direction of such a bearing leaks from the bearing back metal and housing part other than the sliding surface between the shaft (crank pin, crank journal) and the bearing, and leaks into the oil passage for changing the compression ratio. There was a problem in that the oil pressure of the engine decreased, and the function of switching the compression ratio, which was performed by operating a lock pin inside the connecting rod, became insufficient.

[Problem that the invention attempts to solve]

Therefore, the present invention prevents oil from leaking between the backing metal of the bearing (conrod bearing, crankshaft bearing) and the housing, thereby suppressing the drop in oil pressure and preventing the oil pump from increasing its performance. Therefore, it is possible to perform a highly reliable compression ratio switching operation even when the compression ratio is changed.

[Means for solving problems]

According to the present invention, an eccentric bearing is interposed in the shaft support between the piston pin and the connecting rod, and the hydraulically actuated lock pin provided inside the connecting rod is moved in and out of the eccentric bearing to lock and release the eccentric bearing from the connecting rod. In a variable compression ratio mechanism for an internal combustion engine in which hydraulic pressure is applied to the lock pin through oil passages formed inside the crankshaft and connecting rod, the crank pin portion or the journal portion of the crankshaft is connected to the connecting rod shaft, respectively. rotatably supported by a ring-shaped bearing interposed in a branch or an engine block shaft support, and forming a through groove extending in the circumferential direction in the ring-shaped bearing;
A variable compression ratio mechanism for an internal combustion engine, characterized in that a seal member extending in the circumferential direction is provided between the ring-shaped bearing and the connecting rod shaft support or the engine block shaft support and on both sides of the through groove in the axial direction. provided.

〔Example〕

First, in FIGS. 5 to 7, the piston 1 is attached to the small end of the connecting rod 3 via the piston pin 2, and an eccentric bearing 4 is interposed between the piston pin 2 and the small end of the connecting rod 3. equipped. 4a indicates a pin engagement hole formed in the eccentric bearing 4. A pressure chamber 5 is formed inside the cooking rod 3, and a lock pin 6 is slidably installed inside the pressure chamber 5. The high compression ratio side 5a of the pressure chamber 5 is connected to an oil groove 8a formed at the large end of the connecting rod 3 via an oil passage 7.
The low compression ratio side 5b is connected via an oil passage 9 to an oil groove 8b formed in the large end of the connecting rod 3. Crank pin part 1 of crankshaft 10
0A is rotatably fitted to the large end of the connecting rod 3, and the journal portion 10B is fitted to the engine block 11.
It is rotatably supported by a bearing section. The bearing portion of the engine block 11 has the oil groove 8 described above.
Two oil grooves 12 correspond to a and 8b.
a, 12b are formed. Inside the crankshaft 10, these oil grooves 8a,
Oil passages 10a are formed which alternately connect 8b and 12a, 12b. In addition, 30 is a conrod cap, and 31 is a crankshaft bearing cap.

As shown in FIG. 7, the oil groove 12a is connected to the pressure switching valve 15 via an oil passage 13, and the oil groove 12b is connected to the pressure switching valve 15 via an oil passage 16. The pressure switching valve 15 has an oil passage 18,
It communicates with oil in an oil pan (not shown) via an oil pump (not shown). Bypass passages 24 and 25 are connected to the oil grooves 12a and 12b, respectively.
5 is provided with electromagnetic valves 26 and 27, respectively. The solenoid valves 26 and 27 are electrically connected to the pressure switching valve 15.
Depending on the position of the pressure switching valve 15, when one is open, the other is closed. That is, the pressure switching valve 15 is connected to the oil passage 1.
8 and the oil passage 16 to connect the oil passage 18 and the oil passage 1.
3, the solenoid valve 27 is closed and the solenoid valve 26 is open. Conversely, when the pressure switching valve 15 is in a state of connecting the oil passage 18 and the oil passage 13 and blocking the oil passage 18 and the oil passage 16, the solenoid valve 27 is in the open state and the solenoid valve 26 is closed.

In the present invention, the crank pin portion 10A and the journal portion 10B of the crankshaft 10 are rotatable to the large end (housing) of the connecting rod 3 and the shaft support (housing) of the engine block 11, respectively, via the ring-shaped bearings 32 and 33. It is fitted. Each of these ring-shaped bearings 32, 33 consists of two semicircular parts as shown in FIG.

That is, in FIGS. 1 and 6, corresponding semicircular bearings 32a and 32b are inserted in the bearing half holes in the large end of the connecting rod 3 and in the bearing half holes in the connecting rod cap 30, respectively, and the crank pin portion 10A These two semicircular bearings 32a, 32b are fastened to the large end of the conrod cap 30 together with the conrod cap 30. As shown in FIG. 3, the semicircular bearings 32a and 32b are provided with a through groove 34 extending in the circumferential direction corresponding to the oil grooves 8a and 8b of the connecting rod, approximately at the center in the axial direction. 8
It forms part of a and 8b. This through groove 34
As shown in FIG. 3, a semicircular bearing 32a,
Both ends A and B of 32b and two oil grooves 8
Although the partitions C of a and 8b are closed, the ends A and B communicate with each other through an oil groove on the shaft hole side of the connecting rod 3, as shown in FIG. Of course, in the partition portion C, the shaft hole side of the connecting rod 3 is also closed.

Seal of the non-sliding fitting portion between the outer periphery of the ring-shaped bearing 32 consisting of semicircular bearings 32a and 32b, that is, the back metal part, and the large end bearing half hole of the connecting rod 3 and the bearing half hole of the connecting rod cap 30. In order to ensure that the oil grooves 8 in these holes are
O-ring grooves 3 extending in the circumferential direction on both sides of a and 8b
5, 36 are formed, and these O-ring grooves 35, 36
An O-ring 37 is disposed therein. This O-ring 37
As shown in FIGS. 3 and 4, at the junction between both ends A and B of the semicircular bearings 32a and 32b, the oil grooves 8a and Partition C of 8b
The ends of the oil grooves 8a, 8b are surrounded and folded back to prevent oil leakage between the oil grooves 8a, 8b.

8 and 9 show the shaft support of the journal portion 10B of the crankshaft 10, and as in the case of the crank pin portion 10A, the ring-shaped bearing 33 is connected to the bearing half hole and the bearing of the engine block 11. It consists of two semicircular bearings 33a and 33b that correspond to the bearing half holes of the cap 31 and are non-slidingly fitted. The shapes of these semicircular bearings 33a and 33b are similar to the semicircular bearings 32a and 33b of the crank pin portion 10A.
Similarly to the case of 32b, a through groove 38 can be provided and an O-ring 39 can be provided.

In addition, in the above-mentioned embodiment, as a sealing means,
Although an O-ring is provided in the O-ring groove, a gasket may be provided in place of the O-ring, and FIPG
A sealing agent called (formed-in-place gasket) may be applied. In particular, since no slipping occurs between the ring-shaped bearings 32, 33 and the mating bearing hole, such a sealing means can also be used effectively. The shape of the seal can be similar to that of the O-ring described above.

Next, the operation of the compression ratio switching mechanism will be explained. When a signal for switching to a low compression ratio is issued to the pressure switching valve 15 shown in FIG. opens,
The solenoid valve 27 is in a closed state. Therefore, the fifth
Place the crankshaft 1 in the position shown in Figures and Figure 7.
0, the oil passage 10a formed inside the crankshaft 10 connects the oil groove 12b and the oil groove 8b, and oil flows into the low compression ratio side 5b of the pressure chamber 5 through the oil passage 9. try to.
That is, in this state, the pressure on the low compression ratio side 5b of the pressure chamber 5 increases by a constant pressure. Next, when the crankshaft rotates and the oil passage 10a of the crankshaft 10 communicates the oil groove 8a and the oil groove 12a, the oil in the high compression ratio side 5a of the pressure chamber 5 flows through the oil passage 7, the oil groove 8a, and the crankshaft. The oil tries to flow into the oil groove 12a through the 10 oil passages 10a. At this time, the solenoid valve 26 of the bypass passage 24 is open to the atmosphere, so the oil that has flowed into the oil groove 12a is discharged into the oil pan (not shown) through the bypass passage 24 and the solenoid valve 26. . Next, the crankshaft 10 rotates, and the oil groove 12b and the oil groove 8
When b communicates again, the low compression ratio side 5 of the pressure chamber 5
Pressure oil is again supplied to b, and when the crankshaft 10 further rotates and the oil groove 12a and the oil groove 8a communicate with each other, the high compression ratio side 5a of the pressure chamber 5
The oil inside is discharged into the oil pan 21 through the bypass passage 24. While the crankshaft rotates several times in this way, a sufficient amount of oil flows into the low compression ratio side 5b of the pressure chamber 5, the lock pin 6 is housed in the connecting rod, and the eccentric bearing 4 can rotate freely. That will happen. In this way, the switching to the low compression ratio side is completed.

When switching to the high compression ratio side, the switching valve 15 is switched, and at the same time, the solenoid valve 26 of the bypass passage 24 is closed, and the solenoid valve 27 of the bypass passage 25 is opened. Therefore, as the crankshaft 10 rotates, the oil groove 12a and the oil groove 8a are connected through the oil passage 10a, and the pressure chamber 5 is connected to the oil passage 7 via the oil passage 7.
Oil flows into the high compression ratio side 5a of the engine, and the pressure becomes high. At this time, the oil in the low compression ratio side 5b of the pressure chamber 5 has the same pressure as the high compression ratio side 5a, so the lock pin 6 does not protrude yet. When the crankshaft 10 rotates by a certain angle and the oil passage 10a communicates with the oil groove 8b and the oil groove 12b as shown in FIG. Passage 10a, oil groove 12
b. The oil is released to the atmosphere through the bypass passage 25 and the solenoid valve 27 and is discharged into an oil pan (not shown).
Then, similar to the switching to the low compression ratio side described above, while the crankshaft 10 rotates several times, a sufficient amount of oil flows into the high compression ratio side 5a.
Further, since oil is discharged from the low compression ratio side 5b, the lock pin 6 projects smoothly and reliably and fits into the pin engagement hole 4a of the eccentric bearing 4. This completes the switching operation to the high compression ratio side.

[Effect of idea]

In this invention, a ring-shaped bearing is provided at the shaft support of the crankshaft, crank pin, or crank journal, and a sealing means is provided between the back metal part of this bearing and the housing to achieve a seal. This reduces oil leakage and improves the compression ratio. In addition to preventing a drop in the switching oil pressure, this sealing means provides better adhesion between the ring-shaped bearing and the housing, providing a stable shaft support, and improving heat dissipation at the back of the bearing. do.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view taken along the line - in Figure 6, showing the shaft support of the crank pin, Figure 2 is an enlarged cross-sectional view of the portion shown in Figure 1, Figure 3 is a perspective view of the semicircular bearing, and Figure 3 is a perspective view of the semicircular bearing. Figure 4 is a view seen from the arrow in Figure 3, Figure 5 is a sectional view of the variable compression ratio mechanism using eccentric bearings, Figure 6 is a sectional view taken along the line - in Figure 5, and Figure 7 is the same as in Figure 5. A schematic diagram showing the hydraulic path of the variable compression ratio mechanism shown in FIG. 8, a sectional view taken along the line - of FIG. 5, and FIG.
FIG. 2...Piston pin, 3...Conrod, 4...
...Eccentric bearing, 6...Lock pin, 8a, 8
b...Oil groove, 10...Crankshaft, 1
0A... Crank pin portion, 10B... Crank journal portion, 32a, 32b... Semicircular bearing, 34... Penetration groove, 35, 36... O-ring groove, 37... O-ring.

Claims (1)

[Scope of utility model registration request] An eccentric bearing is interposed in the shaft support between the piston pin and the connecting rod, and by moving a hydraulic lock pin provided inside the connecting rod into and out of the eccentric bearing, the eccentric bearing can be locked and unlocked from the connecting rod, and the lock pin is In a variable compression ratio mechanism for an internal combustion engine in which hydraulic pressure is applied through oil passages formed inside the crankshaft and connecting rod, the crank pin portion or journal portion of the crankshaft is connected to the connecting rod shaft support or the engine block shaft support, respectively. It is rotatably supported by a ring-shaped bearing interposed therein, and a through groove extending in the circumferential direction is formed in the ring-shaped bearing, and between the ring-shaped bearing and the connecting rod shaft support or the engine block shaft support, A variable compression ratio mechanism for an internal combustion engine, characterized in that seal members extending in the circumferential direction are provided on both sides of a through groove in the axial direction.