Variable compression ratio device

Patent metadata

Field	Value
Publication number	US-10690049-B2
Application number	US-201916413689-A
Country	US
Kind code	B2
Filing date	May 16, 2019
Priority date	Oct 16, 2018
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A variable compression ratio device may include a connecting rod having a large end portion link-connected to a crankshaft and a small end portion link-connected to a piston by a piston pin, an eccentric cam rotatably installed at the small end portion of the connecting rod and at which the piston pin eccentrically passes through a rotation center, and an low-pressure outer plate and an high-pressure outer plate engaged with both side surfaces of the eccentric cam, formed to partially protrude outward, and selectively engaged with the connecting rod according to a compression ratio. In addition, the low-pressure outer plate and the high-pressure outer plate are selectively engaged with the connecting rod by a controller according to a supply direction of a hydraulic pressure.

First claim

What is claimed is:

1. A variable compression ratio device, comprising:
a connecting rod having a large end portion link-connected to a crankshaft and a small end portion link-connected to a piston by a piston pin;
an eccentric cam rotatably installed at the small end portion of the connecting rod and at which the piston pin eccentrically passes through a rotation center; and
an low-pressure outer plate and an high-pressure outer plate engaged with both side surfaces of the eccentric cam, formed to partially protrude outward, and selectively engaged with the connecting rod according to a compression ratio,
wherein the low-pressure outer plate and the high-pressure outer plate are selectively engaged with the connecting rod by a controller according to a supply direction of a hydraulic pressure.

2. The variable compression ratio device of claim 1 , wherein the low-pressure outer plate and the high-pressure outer plate are formed to partially protrude outward at the same phase.

3. The variable compression ratio device of claim 2 , wherein:
when the compression ratio is a low compression ratio, the low-pressure outer plate is engaged with the connecting rod to direct the protruding portion to face downward; and
when the compression ratio is a high compression ratio, the high-pressure outer plate is engaged with the connecting rod to direct the protruding portion to face upward.

4. The variable compression ratio device of claim 1 , wherein a first oil line to which oil is supplied when the low-pressure outer plate and the connecting rod are engaged, and a second oil line to which the oil is supplied when the high-pressure outer plate and the connecting rod are engaged are formed at the connecting rod.

5. The variable compression ratio device of claim 4 , wherein a latch pin is installed at the connecting rod to be slidable in a direction perpendicular to the connecting rod, and
when the oil is supplied to the first oil line so as to switch a high compression ratio to a low compression ratio in a cylinder, the eccentric cam is engaged with the high-pressure outer plate by the latch pin, and when the oil is supplied to the second oil line so as to switch the low compression ratio to the high compression ratio in the cylinder, the eccentric cam is engaged with the low-pressure outer plate by the latch pin.

6. The variable compression ratio device of claim 5 , wherein
a first latch groove is formed at the low-pressure outer plate to accommodate the latch pin, and
when the oil supplied from the first oil line fills in the first latch groove, the latch pin is moved from the first latch groove to the connecting rod such that a state of the low compression ratio is released.

7. The variable compression ratio device of claim 6 , wherein an inlet hole through which the oil supplied from the first oil line flows into the first latch groove, and a discharge hole through which the oil is discharged from the first latch groove are formed at the first latch groove.

8. The variable compression ratio device of claim 5 , wherein
a second latch groove is formed at the high-pressure outer plate to accommodate the latch pin, and
when the oil supplied from the second oil line fills in the second latch groove, the latch pin is moved from the second latch groove to the connecting rod such that a state of the high compression ratio is released.

9. The variable compression ratio device of claim 8 , wherein an inlet hole through which the oil supplied from the second oil line flows into the second latch groove, and a discharge hole through which the oil is discharged from the second latch groove are formed at the second latch groove.

10. The variable compression ratio device of claim 4 , wherein
an oil chamber is formed at a circumference of the eccentric cam to accommodate the oil supplied from the first oil line, and
when the oil is supplied from the first oil line to the oil chamber, the eccentric cam is rotated to switch a state of a low compression ratio to a state of a high compression ratio.

11. The variable compression ratio device of claim 10 , wherein a separation wall is formed at the connecting rod to separate the oil chamber into two spaces.

12. The variable compression ratio device of claim 11 , wherein an auxiliary chamber communicating with the oil chamber is formed at a front end of the oil chamber to allow a rotation of the eccentric cam to start when the oil is supplied from the first oil line.

13. The variable compression ratio device of claim 12 , wherein a drain line is formed at the connecting rod to communicate a side, at which the auxiliary chamber is not formed, with the outside about the separation wall at the oil chamber.

14. The variable compression ratio device of claim 10 , wherein the connecting rod includes a spool valve configured to discharge the oil filled in the oil chamber to the outside when the state of the high compression ratio is switched to the state of the low compression ratio.

15. The variable compression ratio device of claim 14 , wherein the spool valve includes:
a valve body formed in a cylindrical shape with one closed end and fixed to the connecting rod; and
a plunger slidably installed inside the valve body and configured to communicate the first oil line with the outside while sliding when the state of the high compression ratio is switched to the state of the low compression ratio.

16. The variable compression ratio device of claim 15 , wherein
the first oil line and the second oil line are formed to pass through a circumference of the spool valve, and
a first groove and a second groove are formed with a predetermined depth at positions at which the first oil line and the second oil line pass through a circumference of the valve body.

17. The variable compression ratio device of claim 16 , wherein
a pressure release hole through which the oil supplied to the second oil line flows into the valve body is formed at the second groove, and
a pressure release groove communicating with the pressure release hole and having a predetermined depth toward the closed end of the valve body is formed at an outer side of the plunger to slide the plunger by supplying the oil to the closed end of the valve body.

18. The variable compression ratio device of claim 16 , wherein
an oil discharge hole is formed at the first groove to allow the oil filled in the first oil line to flow into the valve body,
an oil discharge passage is formed at the plunger in a length direction of the plunger and has one end configured to allow the plunger to slide and communicate with the oil discharge hole and the other end through which the oil flowing into the oil discharge hole is discharged, and
a valve discharge hole is formed at a position adjacent to the other end of the valve body and discharges the oil flowing into the oil discharge hole to the outside of the spool valve.

19. The variable compression ratio device of claim 15 , wherein
a cap configured to block an end portion of the valve body is engaged with an opened end portion of the valve body, and
an elastic member configured to elastically support the plunger inward the valve body is installed between the cap and the plunger.

20. The variable compression ratio device of claim 19 , wherein a through-hole is formed at the cap to discharge the oil inside the plunger to the outside.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Choi Myung-Sik

Classifications

• F16K11/07

  with cylindrical slides · CPC title

• F16K3/314

  Forms or constructions of slides; Attachment of the slide to the spindle · CPC title

• F02D15/02

  by alteration or displacement of piston stroke · CPC title

• F02B75/048 Primary

  by means of a variable crank stroke length · CPC title

• F01M2001/066

  Connecting rod with passageways · CPC title