DEVICE FOR CHANGING A COMPRESSION RATIO OF A CYLINDER UNIT OF A RECIPROCATING PISTON COMBUSTION ENGINE

Abstract

A device for changing a compression ratio of a cylinder unit of a reciprocating piston combustion engine is provided. An eccentric bushing is rotatably arranged in a receiving bore hole of a bearing eye of a connecting rod (“conrod”). The conrod bearing eye is formed by a conrod upper part and a conrod lower part, and which surrounds a crankpin of a crankshaft. In addition, the eccentric bushing is rotatably guided in the receiving bore hole and can be locked preferably in two positions which are offset from one another by approximately 180° in the circumferential direction of the eccentric bushing. In order to achieve a targeted rotation of the eccentric bushing in the bore hole of the conrod bearing eye between the locking positions, a freewheel is arranged between an outer casing surface of the eccentric bushing and the receiving bore hole of the conrod bearing eye.

Claims

1. A device for changing a compression ratio of a cylinder unit of a reciprocating piston combustion engine, comprising an eccentric bushing rotatably arranged in a receiving bore hole of a connecting rod bearing eye of a connecting rod, said connecting rod bearing eye being formed by an upper part and a lower part, and which surrounds a crankpin of a crankshaft, wherein the eccentric bushing is rotatably guided in the receiving bore hole and is lockable in two positions which are offset from one another by approximately 180° in a circumferential direction of the eccentric bush, wherein a freewheel is arranged between an outer casing surface of the eccentric bushing and the receiving bore hole of the connecting rod bearing eye.

2. The device according to patent claim 1, wherein the freewheel is formed as a roller freewheel.

3. The device according to patent claim 1, wherein the freewheel is formed as a clamping body freewheel.

4. The device according to claim 2, wherein the roller freewheel includes clamping rollers guided in a cage and that clamping ramps on the outer casing surface of the eccentric bushing.

5. The device according to claim 1, wherein rolling bearings or plain bearings are formed on both sides of the freewheel above which the eccentric bushing is arranged across from the location hole.

6. The device according to claim 1, wherein the eccentric bushing is provided with boards running outwards radially, which are guided slidingly on both axially directed front faces of the upper part and the lower part.

7. The device according to claim 1, wherein the freewheel is formed as a wrap-spring freewheel, wherein one end of at least one wrap-spring is coupled with the connecting rod bearing eye.

8. The device according to claim 7, wherein the end of the at least one wrap spring is attached in the parting plane between the upper part and the lower part.

9. The device according to claim 7, wherein the wrap-spring freewheel includes two wrap-springs, with spiral-like windings run parallel to one another.

10. The device according to claim 7, wherein the wrap-spring freewheel is arranged in a ring-shaped recess that extends within the upper part and the lower part and that includes a rectangular cross section.

11. An assembly for changing a compression ratio of a cylinder unit of a combustion engine, the device comprising: a connecting rod having an inner surface defining an opening configured to receive a crankpin of a crankshaft; a bushing rotatably arranged in the opening and having an outer surface, wherein the bushing includes one or more pockets configured to receive a locking member to lock the bushing and inhibit rotation of the bushing; and a freewheel arranged between the outer surface of the bushing and the inner surface of the connecting rod, the freewheel contacting the bushing to enable rotation of the bushing in a first direction while preventing rotation of the bushing in a second direction.

12. The assembly of claim 11, wherein the one or more pockets is a plurality of pockets each configured to receive the locking member.

13. The assembly of claim 12, wherein the pockets are separated by 180 degrees about the bushing from one another.

14. The assembly of claim 12, wherein the bushing includes a pair of opposing flanges and the freewheel is disposed between the flanges, wherein each flange includes one of the plurality of pockets.

15. The assembly of claim 12, wherein the locking device is selectively received by the plurality of pockets to selectively lock the bushing.

16. The assembly of claim 11, wherein the connecting rod is attachable to a crankshaft extending along an axis, and the locking member is moveable into and out of the one or more pockets in a direction parallel to the axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a further explanation of embodiments of the invention, the drawing is referred to representing several different execution examples in a simplified manner. The following is shown:

[0020] FIG. 1 as a perspective representation, a partial view of a crankshaft with a conrod arranged on a crankpin recording a working piston, which is cut in the area of its conrod lower part,

[0021] FIG. 2 a partial view of the conrod with a partial section through a crankpin and a cam disc,

[0022] FIG. 3 a perspective representation of an eccentric bushing that includes a roller freewheel on an outer casing surface,

[0023] FIG. 4 an eccentric bushing with a roller freewheel,

[0024] FIG. 5 a roller freewheel that has roller bearings arranged to it on both sides,

[0025] FIG. 6 a perspective representation of the eccentric bushing provided with the roller freewheel,

[0026] FIG. 7 a perspective representation of a cage intended for the roller freewheel,

[0027] FIG. 7A a perspective representation of another version of a cage intended for the roller freewheel,

[0028] FIG. 7B an enlarged section VII b in FIG. 7A,

[0029] FIG. 7C an enlarged section VII c in FIG. 7A,

[0030] FIG. 8 as perspective representation, a conrod cut sideways, whereby a wrap-spring freewheel is arranged between a conrod eye and an eccentric bushing,

[0031] FIG. 9 an enlarged representation of the conrod bearing eye of the conrod represented in FIG. 7

[0032] FIG. 10 a perspective representation to explain the assembly of a wrap-spring on a crankpin of a crankshaft,

[0033] FIG. 11 a wrap-spring freewheel made from two wrap-springs wrapped inside each other, and

[0034] FIG. 12 in a longitudinal section, a partial view of an eccentric bushing that is provided with a double winded wrap-spring freewheel, equipped with roller bearings on its two sides.

DETAILED DESCRIPTION

[0035] A crankshaft of a reciprocating piston combustion engine is designated 1 in FIG. 1, of which only one partial section is represented consisting of four crank webs 2, 3, 4, and 5. The crank webs 2 and 5 are thereby provided with counterweights 6 for mass balance and insofar differ from the crank webs 3 and 4. A crankpin 7 is furthermore formed between the crank webs 2 and 3 for the inclusion of a connecting rod (“conrod”) not explained in detail, while the crank webs 3 and 4 run on both sides of a main bearing pin 8, above which the crankshaft 1 is stored in a crankcase of the reciprocating piston combustion engine not explained in detail. Finally, a crankpin is intended again between the two crank webs 4 and 5, which is however not visible in this representation as a conrod is arranged on it. Due to the offset of the crankshaft 1, this non-visible crankpin assumes a different position compared to the crankpin 7.

[0036] This conrod 9 consists of a conrod upper part 10 and a conrod lower part 11 that are connected with each other by screws 12. The conrod upper part 10 includes a working piston 13 on its end facing away from the conrod lower part 11, which is attached to the conrod upper part by means of a piston pin 14 with a piston pin bearing not explained in detail as well as a conrod eye. A parting plane 15 between the conrod upper part 10 and the conrod bottom part 11 runs through a conrod bearing eye that is also not visible in the perspective representation of FIG. 1, as already stated, as the conrod 9 is installed on the respective crankpin of the crankshaft 1.

[0037] An eccentric bushing 16 is arranged in this conrod bearing eye 16 that has boards 17 and 18 running outwards. The eccentric bushing 16 is guided on the face through the boards 17 and 18 both on the conrod upper part 10 and the conrod bottom part 11. It can be seen from the partial section through the conrod bottom part 11 according to FIG. 1 that a cylindrical locking element 19 is arranged moveable axially, therefore in parallel to the longitudinal axis of the crankshaft 1 in it. This locking element 19 has a radial running cylindrical carrier 20, which engages in a carrier groove 21 of a cam disc 22 at times, meaning in the area of a bottom dead center of the working piston 13. This cam disc 22 arranged in an oil sump of the reciprocating piston combustion engine is arranged moveably in longitudinal direction of the crankshaft 1 and is moved accordingly by means of adjusting means not described in more detail. It can thus move the locking element 19 in the direction of one of the two boards 17 or 18 through its carrier groove 21 recording the carrier 20. The carrier groove 21 and be widened in the inlet area for the carrier 20 and can taper off continuously to the discharge area to offset possible tolerances.

[0038] There is a locking bore in each of the boards that the locking element 19 can be moved into. FIG. 1 has the locking element 19 with its respective end in a locking hole 23 of the board 17. The respective position of this locking hole 23 of board 17 to a locking bore intended in board 18 will still be addressed in connection with the following FIGS. 3, 4, and 6.

[0039] A section of the conrod 9 is represented in FIG. 2 in the area of a conrod bearing eye 24, which is formed by a half-shell formation of the end section of the conrod upper part 10 and the entire conrod lower part 11. The conrod upper part 10 and the conrod lower part 11 are fixated to each other with screws 12 and jointly form a location hole 25. The eccentric bushing 16 is arranged in this location hole 25, which is thus guided rotational in the location hole 25. The eccentric bushing 16 also consists of two half shells 16a and 16b, whereby the two boards 17 and 18 of the eccentric bushing 16 are thus also arranged to these half shells accordingly, and which are executed by means of circular ring sections described with 17a, 17b as well as 18a and 18b. But only the board 17 is visible in FIG. 2 so that also only half of the circular ring section 17a is shown.

[0040] For clarification of the arrangement, the conrod bearing eye 24 is represented as a half-section in FIG. 2 so that the locking element 19 with the carrier is visible in its arrangement in the conrod lower part 11. The locking element 19 has a snap contour that works together with a spring-loaded locking pin 27. The arrangement of the cam disc and its interaction with the carrier is also shown in FIG. 2.

[0041] As is furthermore shown in FIG. 3, a freewheel 29 is arranged on an outer casing surface 28 of the eccentric bushing 16 that is formed as a roller freewheel in this case. For this purpose, the outer casing surface 28 of the eccentric bushing 16 is provided with clamping ramps that run outwards in a radially angular manner, and which are not displayed in detail in FIG. 3. This representation furthermore shows that the eccentric bushing 16 is provided with sliding surfaces 31 and 32 on axial sections of its outer casing surface 28 to form a plain bearing. The two boards 17 and 18 that together with the hollow cylindrical section of the eccentric bushing 16 are halved into partial sections 17a and 17b as well as 18a and 18b have locking holes 23 and 33 that are offset to each other by 180°. Clamping rollers 30a of the roller freewheel are guided rotationally in a cage 34. The embodiment according to FIG. 3 furthermore has a carrier 20a formed with a rectangular cross section. The cam disc 22 in this case is provided with a carrier groove that is formed relatively wide in the inlet area for the carrier 20a and which continuously tapers off to the outlet area so that tolerances can be offset.

[0042] The eccentric bushing 16, as already explained in connection with FIG. 2, will be arranged in the location hole 25 of the conrod bearing eye 24, whereby the boards 17 and 18 are guided sliding on the front faces of the conrod bearing eye 24. The eccentric bushing 16 is also guided through the sliding surfaces 31 and 32 as well as the roller free wheel 30 in the location hole 25. The roller freewheel ensures that a rotation of the eccentric bushing 16 across from the conrod bearing eye 24 is only possible in one direction of rotation, while the roller freewheel 30 blocks the rotary motion in the other direction of rotation.

[0043] The arrangement of the roller freewheel 30 comprising the cage 34 on the outer casing surface 28 of the eccentric bushing 16 is shown once more in FIG. 4. The eccentric bushing 16 is thereby shown in a position, in which the locking hole is visible.

[0044] An alternative embodiment of a cage 42 is represented in FIG. 5, which is formed in a middle area for the inclusion of clamping rollers 30a of the roller freewheel 30 and which has pockets 43 for the inclusion of cylindrical rolling elements next to this area. A roller bearing is thus created on both sides of the roller freewheel.

[0045] With regard to the formation of the eccentric bushing, FIG. 6 is referred to, which shoes it in a different perspective, in which a locking hole 23 of the board 17 is visible. The eccentric bushing 16 can be formed as a plain bearing 36 on its inner casing surface 35; above which the conrod 9 is arranged on the respective crankpin of the crankshaft 1.

[0046] FIG. 7 shows the cage 34 that comprises the cage halves 34a and 34b and which is intended for the inclusion of the clamping rollers 30a of the roller freewheel. The cage ends are thereby guided together through cage locks 37 and 38. Each of these cage locks 37 or 38 consists of an end piece 39 formed as a dovetail and an end piece 41 comprising a slot 40. The cage halves 34a and 34b can thus perform radial compensation movements to one other.

[0047] Another embodiment of the cage 34 is represented in FIG. 7A in connection with the FIGS. 7B and 7C. This cage 34 is formed as one piece and has a bending point 34c and a cage lock 34d.

[0048] According to another embodiment, per FIG. 8, a conrod 45 shall consist of a conrod upper part 46 and a conrod bottom part 47, whereby a piston pin bearing 48 is formed on one end of the conrod upper part 46. The conrod 45 further comprises a conrod bearing eye 49, in whose receiving bore hole an eccentric bushing is rotatably mounted. Both the conrod upper part 46 and the conrod lower part 47 are provided with a recess 52 comprising a rectangular cross section, which consequently encompasses the eccentric bushing 51 on an outer casing surface 53.

[0049] As can be seen from FIG. 8 in connection with FIG. 9, a wrap-spring freewheel 54 is arranged within this recess, which thus wraps the eccentric bushing 51 on its outer casing surface 53. The respective wrap spring 55 is thereby fixated on the conrod bearing eye 49 on its one end. A respective wrap-spring freewheel 54 enables a rotation of the eccentric bushing 51 in one direction of rotation across from the conrod bearing eye 49 and prevents a rotation in the other direction of rotation. The eccentric bushing 51 is formed hollow cylindrical overall in this case, therefore without ribs.

[0050] A pilot hole 56 is intended in the conrod lower part 47, in which a sliding guideway 57 is arranged. The sliding guideway 57 has end sections 58 and 59, in which it is provided with a recess or a reduced diameter. Actuating pins 60 and 61 are furthermore provided for in the bottom part of the piston, which run radially to the sliding guideway 57. These actuating pins 60 and 61 work together with tie pins 62 and 63, which are arranged in radial lock holes 64 and 65 of the eccentric bushing 51. The lock holes 65 and 65 that are located on circumferential tracks of the eccentric bushing 51, which are offset to each other axially, are thereby preferably formed as bored holes, in which the tie pins are supported through springs 66, 67. The sliding guideway 57 thereby also comprises a carrier, which is activated through a cam disc that is movable in axial direction in the same way as is portrayed in FIG. 1.

[0051] When the sliding guideway 57 assumes a position, in which the respective actuating pin 60 or 61 is located in one of the end sections 58 or 59, the respective tie pin 62 or 63 can exit the lock hole 64 or 65 and can consequently lock the eccentric bushing 51 across from the conrod bearing eye 49. According to FIG. 9, this is the case for the tie pin 62 exiting from the lock hole 64.

[0052] The additional FIG. 10 shows a shaft stub, by means of which the assembly of a wrap-spring 69 on a crankpin is supposed to be shown. An end of the wrap spring is thereby guided around the shaft stub and is then continuously wrapped around the shaft stub 68. As the eccentric bushing 51 consists of half shells 51a and 51b in accordance with FIGS. 8 and 9, and they don't have a rib, these half shells 51a and 51b can subsequently be inserted between the wrap spring 69 and the respective crankpin.

[0053] According to FIG. 11 provision is made for that the wrap-spring freewheel 54 has another wrap spring beside the already named wrap spring 69, and that these two wrap springs 69 and 70 are wound up inside each other in spiral form.

[0054] According to FIG. 12, the eccentric bushing 51 is provided with a double-wound wrap-spring freewheel 54, beside which roller bearings 71 and 72 are intended on each side. Plain bearings may also be provided for instead of the two rolling bearings.

LIST OF REFERENCE SIGNS

[0055] 1 Crankshaft [0056] 2 Crank web [0057] 3 Crank web [0058] 4 Crank web [0059] 5 Crank web [0060] 6 Counterweight [0061] 7 Crankpin [0062] 8 Main bearing pin [0063] 9 Conrod [0064] 10 Conrod upper part [0065] 11 Conrod lower part [0066] 12 Screw [0067] 13 Working piston [0068] 14 Piston pin [0069] 15 Parting plane [0070] 16 Eccentric bushing [0071] 16a Half shell of 16 [0072] 16b Half shell of 16 [0073] 17 Board [0074] 17a Section of 17 [0075] 17b Section of 17 [0076] 18 Board [0077] 18a Section of 18 [0078] 18b Section of 18 [0079] 19 Locking element [0080] 20 Carrier [0081] 21 Carrier groove [0082] 22 Cam disc [0083] 23 Locking holes [0084] 24 Conrod bearing eye [0085] 25 Location hole [0086] 26 Snap contour [0087] 27 Locking pin [0088] 28 Outer casing surface of 16 [0089] 29 Freewheel [0090] 30 Roller freewheel [0091] 30a Clamping rollers of 30 [0092] 31 Sliding surface [0093] 32 Sliding surface [0094] 33 Locking hole [0095] 34 Cage [0096] 34a Half shell of 34 [0097] 34b Half shell of 34 [0098] 34c Bending point of 34 [0099] 34d Cage lock [0100] 35 Inner casing surface [0101] 36 Plain bearings [0102] 37 Cage lock [0103] 38 Cage lock [0104] 39 Dovetail-like end piece of 34a and 34b [0105] 40 Slot [0106] 41 End piece of 34a and 34b [0107] 42 Cage [0108] 43 Pockets [0109] 44 Cylindrical rolling elements [0110] 45 Conrod [0111] 46 Conrod upper part

[0112] 47 Conrod lower part

[0113] 48 Piston bin bearings [0114] 49 Conrod bearing eye [0115] 50 Receiving bore hole [0116] 51 Eccentric bushing [0117] 52 Recess [0118] 53 Outer casing surface [0119] 54 Wrap-spring freewheel [0120] 55 Wrap-spring [0121] 56 Pilot hole [0122] 57 Sliding guideway [0123] 58 End section [0124] 59 End section [0125] 60 Actuating pin [0126] 61 Actuating pin [0127] 62 Tie pin [0128] 63 Tie pin [0129] 64 Lock hole [0130] 65 Lock hole [0131] 66 Spring [0132] 67 Spring [0133] 68 Shaft stub [0134] 69 Wrap spring [0135] 70 Wrap spring [0136] 71 Roller bearing [0137] 72 Roller bearing