Device for changing a compression ratio of a cylinder unit of a reciprocating-piston internal combustion engine

Patent metadata

Field	Value
Publication number	US-10184408-B2
Application number	US-201515505190-A
Country	US
Kind code	B2
Filing date	Jun 16, 2015
Priority date	Aug 20, 2014
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

A device for changing a compression ratio of a cylinder unit of a reciprocating piston internal combustion engine has an eccentric bushing which is rotatably arranged in a bore of a connecting rod eye. Said eye encloses a crank pin of a crankshaft, and the bushing is rotatably guided in the bore and can be locked via locking openings, which are arranged to be offset from each other by preferably approximately 180°. The connecting rod has a locking apparatus which interacts optionally with the locking openings and via which the eccentric bushing can only ever be transferred from one position to the next. The locking apparatus has a sliding guideway extending parallel to the longitudinal axis of the bore of the connecting rod bearing eye. The sliding guide interacts with actuating pins arranged in the locking openings and can be displaced radially with respect to the bushing.

First claim

The invention claimed is:

1. A device for changing a compression ratio of a cylinder unit of a reciprocating piston internal combustion engine, comprising:
an eccentric bushing rotatably arranged in a receiving bore hole of a connecting rod bearing eye of a connecting rod upper part and a connecting rod lower part, the eccentric bushing surrounding a crankpin of a crankshaft wherein the eccentric bushing is rotatably guided in the receiving bore hole and can be locked via locking devices disposed in locking openings located in positions which are offset from one another about the eccentric bushing, and wherein the eccentric bushing is positively fixable in the respective positions in the connecting rod bearing eye, wherein the locking device has a sliding guideway parallel to a longitudinal axis of the bore hole of the connecting rod bearing eye and the locking devices interacts with actuating pins arranged in the locking openings and movable radially relative to the eccentric bushing.

2. The device of claim 1 , wherein the locking openings are provided in the connecting rod lower part and are arranged on different circumferential tracks to the outer casing surface of the eccentric bush and radial lock holes of the eccentric bush accommodate tie pins that are radially pre-stressed outwards by compression springs, which align with the locking openings and are arranged on a respective circumferential track depending on the position of the eccentric bushing as well as the respective actuating pin, and wherein the sliding guideway is movable lengthwise in the connecting rod lower part and interacts with ends of the actuating pins facing away from the eccentric bushing.

3. The device of claim 2 , wherein the sliding guideway comprises end sections that are offset.

4. The device of claim 3 , wherein the sliding guideway is formed cylindrically and comprises end sections that are reduced in diameter.

5. The device of claim 1 , wherein a freewheel is arranged between an outer casing surface of the eccentric bushing and the bore hole.

6. The device of claim 5 , wherein the freewheel is formed as a roller freewheel with clamping rollers guided in a cage, wherein clamping ramps are formed on the outer casing surface of the eccentric bushing.

7. The device of claim 5 , wherein the freewheel is formed as a wrap-spring freewheel.

8. The device of claim 1 , wherein the eccentric bushing substantially runs across its entire length within the bore hole.

9. The device of claim 1 , wherein the eccentric bushing comprises two half shells.

10. The device of claim 1 , wherein the locking openings are located 180 degrees from one another about the eccentric bushing.

11. A connecting rod configured to selectively change a compression ratio of an internal combustion engine, the connecting rod comprising:
an upper part and a lower part assembled together to define a bore hole, wherein the lower part defines a radially extending locking opening;
an eccentric bushing rotatably supported within the bore hole, the bushing defining a radially-extending lock hole;
a first pin slideably disposed in the lock hole of the eccentric bushing; and
a second slideably disposed within the locking opening and configured to selectively engage the second pin to inhibit rotation of the bushing with respect to the bore hole.

12. The connecting rod of claim 11 , wherein the lower part defines a location hole extending parallel to a central axis of the bore hole, and a guideway is located and slideable within the location hole.

13. The connecting rod of claim 12 , wherein the guideway selectively engages the second pin and forces the second pin along the lock opening to lock the bushing to the at least one of the upper part and lower part.

14. The connecting rod of claim 12 , wherein the guideway includes a carrier extending radially therefrom, the carrier being selectively engagable within a groove of a cam disc when a piston connected to the connecting rod is located at a bottom dead center position.

15. The connecting rod of claim 14 , wherein the carrier contacts the cam disk to longitudinally slide the guideway within the location hole and into engagement with the second pin to lock the bushing.

16. The connecting rod of claim 12 , wherein the guideway includes two end regions on either side of a central region, wherein the end regions have a smaller diameter than the central region.

17. The connecting rod of claim 11 , further comprising a spring in the lock hole of the eccentric bushing to bias the first pin away from the bore hole.

18. The connecting rod of claim 11 , further comprising a freewheel arranged radially between an outer surface of the eccentric bushing and an inner surface of the bore hole.

19. A connecting rod configured to selectively change a compression ratio of an internal combustion engine, the connecting rod comprising:
a cylindrical surface defining a bore hole configured to attach to a crankshaft, the cylindrical surface defining a first radially extending opening;
an eccentric bushing rotatably supported within the bore hole, the bushing defining a second radially extending opening aligned with the first radially extending opening to define a common opening;
one or more pins slidably disposed within the common opening;
wherein the connecting rod defines a third opening extending parallel to a central axis of the bore hole; and
a guideway slidably disposed in the third opening and configured to selectively engage the one or more pins to press the one or more pins toward the bushing to lock the bushing with respect to the bore hole.

Assignees

• Schaeffler Technologies Ag

Inventors

• Popp Markus
• Moeller Andreas
• Doerrie Swen

Classifications

• F16C7/023

  for piston engines, pumps or the like · CPC title

• F02B75/048 Primary

  by means of a variable crank stroke length · CPC title

• F16C2360/22

  Internal combustion engines · CPC title

• F02D15/02 Primary

  by alteration or displacement of piston stroke · CPC title

• F16C7/06

  Adjustable connecting-rods · CPC title