SWITCHING RACK FOR A VARIABLE COMPRESSION RATIO CONNECTING ROD AND A VEHICLE COMPRISING SUCH A SWITCHING RACK

Abstract

A combustion engine comprising a switching rack and a plurality of connecting rods, where the switching rack comprises a longitudinal body having a face side and a rear side, where the face side comprises a plurality of switching arrangements where each switching arrangement comprises a first cam and a second cam, where each switching arrangement is adapted to interact with a switch on a connecting rod, and where the switching rack is arranged in a gliding manner in a groove between a cylinder block and an engine bedplate of the combustion engine. The advantage of the invention is that a means for switching a variable compression switch in a connecting rod in a combustion engine can be mounted in a simple and reliable manner.

Claims

1.-13. (canceled)

14. A combustion engine comprising a switching rack and a plurality of connecting rods, where the switching rack comprises a longitudinal body having a face side and a rear side, where the face side comprises a plurality of switching arrangements, where each switching arrangement comprises a first cam and a second cam, where each switching arrangement is adapted to interact with a switch on a connecting rod, where the switching rack is arranged in a gliding manner in a groove between a cylinder block and an engine bedplate of the combustion engine.

15. The combustion engine of claim 14, where the rear side of the body of the switching rack is provided with an actuating lever adapted to slide the switching rack sideways.

16. The combustion engine of claim 14, where the body of the switching rack comprises a first protruding end stop and a second protruding end stop adapted to cooperate with stop surfaces of the groove.

17. The combustion engine of claim 14, where each cam of the switching rack is provided with an entrance region and a switching region.

18. The combustion engine of claim 14, where the first cam and the second cam of the switching rack extend perpendicular from the face side.

19. The combustion engine of claim 18, where the entrance region and the switching region of each cam in a switching arrangement face each other.

20. The combustion engine of claim 14, where the cross section of the body of the switching rack is rectangular.

21. The combustion engine of claim 14, where a switching arrangement of the switching rack comprises an interconnection which interconnects the first cam with the second cam.

22. The combustion engine of claim 14, where the switching rack is arranged in a groove in the cylinder block of the combustion engine.

23. The combustion engine of claim 14, where the switching rack is arranged in a groove in the engine bedplate of the combustion engine.

24. The combustion engine of claim 14, where the combustion engine comprises an actuator mounted on the outside of the engine bedplate adapted to control the switching rack.

25. The combustion engine of claim 24, where the actuator is a rotary electric motor.

26. A vehicle comprising the internal combustion engine of claim 14.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0016] The invention will be described in greater detail in the following, with reference to the attached drawings, in which:

[0017] FIG. 1 shows a switching rack according to the invention standing on a bedplate,

[0018] FIG. 2 shows a front view of the switching rack according to the invention standing on a bedplate,

[0019] FIG. 3 shows a bottom view of a cylinder block with a groove for a switching rack according to the invention,

[0020] FIG. 4 shows a bottom view of a cylinder head with a switching rack according to the invention,

[0021] FIG. 5 shows a view of a connecting rod comprising a switch,

[0022] FIG. 6 shows a detail of a switching rack according to the invention during an interaction with a switch, and

[0023] FIG. 7 shows a vehicle comprising an internal combustion engine according to the invention.

DESCRIPTION OF EMBODIMENTS

[0024] The embodiments of the invention with further developments described in the following are to be regarded only as examples and are in no way to limit the scope of the protection provided by the patent claims.

[0025] FIG. 1 shows a switching rack 1 standing on an engine bedplate 21 of an internal combustion engine 31. The switching rack 1 is provided with a body which comprises longitudinal regions and which interconnects the switching arrangements 7 of the switching rack. The body is provided with a face side 3 which is pointing upwards in the figure. The rear side 4 is at the opposite side. The switching rack 1 is also provided with a first end stop 5 and a second end stop 6. The rear side 4 is provided with an actuating lever 12 that is controlled by an actuator 13 mounted on the outside of the bedplate 21. The actuator controls the switching rack to either a right position or a left position. The actuator is provided with a sealing that will prevent oil from escaping through the mounting hole for the axle of the actuator. The actuator is here a rotary electric motorwith an eccentric wheel acting on the actuating lever. A linear actuator, such a solenoid, would also be possible to use.

[0026] A switching arrangement 7 is provided at each cylinder of the engine. In the shown example, a three cylinder engine is used as an example, but any number of cylinders is plausible. The switching arrangement extends from the body of the switching rack in a substantial perpendicular direction from the face side of the body. A switching arrangement comprises a first cam 8 and a second cam 9, which are spaced apart such that the connecting rod attachment to the crankshaft with the switch can pass between the cams. The first cam 8 and the second cam 9 are interconnected with an interconnection 14, which also helps to stabilize the switching rack. The upper part of a cam comprises an entrance region 10 and the lower part of a cam comprises a switching region 11, which will interact with the switch of the connecting rod. The entrance region will allow the switch to enter the switching region in a gentle way. The entrance region has a shape of a ramp that will allow a smooth movement of the actuating means of the switch without creating audible noise and which will further prevent excessive wear of the switch and the entrance region.

[0027] The entrance region 10 and the switching region 11 are provided on an inner surface of a cam. The inner surface of the first cam 8 and the inner surface of the second cam 9 are directed towards each other. The inner surfaces are slightly angled outwards with respect to a centre plane between the first cam 8 and the second cam 9, such that the distance between the entrance regions is larger than the distance between the switching regions.

[0028] FIG. 2 shows a front view of the switching rack 1. In the shown example, the switching rack is in the left position, i.e. positioned as far left as possible such that the first end stop 5 will bear on the end stop surface 25 of the mounting groove 22. The first cam 8 will now be able to interact with the switch of the connecting rod such that the switch will be pushed to a second position every time the switch passes the first cam, i.e. at every revolution. The second position may e.g. allow oil to flow to the second cylinder, such that the piston mount is in the lower position.

[0029] FIG. 3 shows a bottom view of a cylinder block 20 with a groove 22 for a switching rack 1. The groove is provided in each bearing bridge 24 of the cylinder block. The groove 22 further comprises a first end stop surface 25 and a second end stop surface 26 adapted to interact with the first end stop 5 respectively the second end stop 6 of the switching rack. The face side 3 of the switching rack 1 will bear and slide in the groove 22 in the cylinder block.

[0030] FIG. 4 shows a switching rack 1 positioned in the groove 22 of the cylinder block 20. In the shown position, the switching rack is seen from below and is in the left position with the first end stop 5 bearing on the first end stop surface 25. The switching rack is controlled to the left position by the actuator 13 through the actuating lever 12. The actuator is adapted to be attached to the outside of the bedplate.

[0031] FIG. 5 shows a connecting rod 15 arranged to connect a crankshaft to a piston. In the shown figure, the switch 18 is arranged in the upper part of the connecting rod, above the split plane. The switch is arranged at one side of the connecting rod. The switch will switch between two pressurized oil channels comprised in the connecting rod. In the shown first position, the switch will allow oil to flow to a first cylinder 16 arranged at the piston mount 19 of the piston. The first cylinder will position the piston mount in a first, raised position, such that the effective length of the connecting rod will be at its longest extension which corresponds to a high compression ratio. In the second position, the second cylinder 17 will position the piston mount in a second, lower position in which the effective length of the connecting rod is shorter. This will in turn provide a lower compression in the cylinder.

[0032] FIG. 6 shows a detail of the switching rack during an interaction with a switch 18 of a connecting rod 15. In the shown example, the switch is in the second position and the switching rack has just been positioned in the left position. The switch 18 is in the shown example at the entrance region 10 of the first cam 8 and will continue downwards in the figure. The switch will now be pressed into the connecting rod by the inclined surface of the entrance region 10. When the switch continues downwards, it will be pushed in completely into the connecting rod by the switching region 11 and the other end of the switch will extend outwards towards the second cam 9, and the switch will change position to the first position. The switching rack will remain in the left position until a signal is sent to the actuator to change position. This means that the switch will be pushed in every time it passes the first cam if it should displace somewhat, e.g. due to vibrations or the like.

[0033] FIG. 7 shows a vehicle 30 comprising an internal combustion engine 31. The internal combustion engine 31 comprises a switching rack 1 arranged in groove between the cylinder block 20 and the engine bedplate 21.

[0034] The invention is not to be regarded as being limited to the embodiments described above, a number of additional variants and modifications being possible within the scope of the subsequent patent claims.