WO2014162043A1

WO2014162043A1 - Arrangement for setting a compression ratio of an internal combustion piston engine

Info

Publication number: WO2014162043A1
Application number: PCT/FI2014/050124
Authority: WO
Inventors: Ville HEIKKILÄ; Ossi LAAKSO; Janne MÄENPÄÄ
Original assignee: Wärtsilä Finland Oy
Priority date: 2013-04-03
Filing date: 2014-02-20
Publication date: 2014-10-09

Abstract

Invention to an arrangement for setting a compression ratio of an internal combustion piston engine, which arrangement provides a power transmission connection between a piston and a crank shaft of the engine when assembled, and which arrangement comprises a body part (106) having a first end (106.1) and a second end (14.2) for attaching the body part at its ends to a respective housing and between the first and the second ends there is an eccentric sleeve arranged for attaching the arrangement (104) to a housing of the connecting rod (105) via the sleeve, characterized in that arrangement comprises a hydraulic rotation suppression system (110) arranged to allow or suppress rotation of the eccentric sleeve (108) in respect to the connecting rod, which hydraulic rotation suppression system comprises a hydraulic circuit (112) having a valve member (114) arranged to close or open the circuit, and a hydraulic fluid displacement part (124) arranged to displace hydraulic fluid in the hydraulic circuit in interaction with the rotational position eccentric sleeve (108).

Description

Arrangement for setting a compression ratio of an internal combustion piston engine

Technical field

[001 ] The present invention relates to arrangement for setting a compression ratio of an internal combustion piston engine.

[002] Such an arrangement provides a power transmission connection between a piston and a crank shaft of the engine when assembled, and which arrangement comprises a body part having a first end and a second end for attaching the body part at its ends to a respective housing and between the first and the second ends there is an eccentric sleeve arranged for attaching the arrangement to a housing of the connecting rod via the sleeve.

Background art

[003] In internal combustion piston engines the reciprocating movement of the piston is transformed into a rotating movement of the crankshaft by connecting each piston via a connecting rod to the crankshaft. In a trunk piston engine the pis- ton has been installed by a small end bearing to the connecting rod so that the connecting rod may rotate in relation to the piston. It is known in the art to attach a piston to a connecting rod by means of a floating piston pin. In this solution the piston pin has been arranged against the bearing surfaces of the connecting rod so that in operation it can rotate into any position. In other words only the movement of the pin in the longitudinal direction is limited. Another piston pin type is a locked pin. This kind of the piston pin is locked also for the rotating movement either to the piston or the connecting rod, thus it cannot rotate even during the running of the engine.

[004] Attempts to provide dynamic i.e. on the fly variable compression ratio in an internal combustion piston engine have been made since long time ago. One of the most common ways of approach to this includes an effective lengthening and shortening of the connecting rod, which joins the reciprocating piston to a rotating crankshaft. Some of the solutions are proposing an eccentric piston pin connection provided at the articulating joint between the small end of the connecting rod and the piston.

[005] For example DE 19503425 discloses a piston engine in which the effective length of the connecting rod may be adjusted. A piston pin which joins the connecting rod to the piston is provided with an eccentric bushing. The eccentric bushing is provided with fixed stop discs at its ends, protruding axially over either sides of the small end of the connecting rod. There are stop notches arranged to the rim of the disks which together with a locking member may retain the bushing at two positions corresponding two effective lengths of the connecting rod.

[006] GB 2454340 discloses a variable compression ratio piston and connecting rod assembly for an internal combustion engine which includes an eccentric bush- ing that carries a piston pin bushing and contains a journaled portion held in the rod bore of the connecting rod. The eccentric bushing can be selectively rotated between either of two rotary adjusted positions to effect a change in the height of the piston relative to the connecting rod and thus change the compression ratio of the assembly. [007] EP0219634 describes compression ratio changing device for an internal combustion engine using an eccentric bearing interposed between a piston pin and a connecting rod. A lock hole is formed in the eccentric bearing and a lock pin hole is formed in the connecting rod. A lock pin is slidably inserted in the lock pin hole and it may move into or out of the lock hole in the eccentric bearing. When the lock pin engages lock hole, the rotation of the eccentric bearing is locked. When the lock pin moves apart from the lock hole, the rotation of the eccentric bearing becomes free. To obtain a smooth entry of the lock-pin into the lock hole, a guide groove is formed in the outer portion of the eccentric bearing.

[008] JP 6129272 discloses a variable compression ration device of an engine. There are two radially extending lock pins arranged in connection with a piston pin at specified angles. There is an eccentric sleeve with a through hole to cooperate with the lock pins and a sleeve pin in the through hole facing the lock pins. There is also a connecting rod pin facing them provided on a connecting rod. The connecting rod pin is arranged to reciprocally fix and release the piston pin, the eccentric sleeve and the connecting rod by way of pushing and pulling the connecting rod pin to shift the engine between high and low compression ratio states. The connecting rod pin is operated hydraulically.

[009] The solutions described are practically substantially complex or have shortcomings in respect to their operation.

[0010] It is an object of the invention to provide an arrangement for setting a compression ratio of an internal combustion piston engine which provides simple and reliable construction and well controllable operation.

Disclosure of the Invention

[001 1 ] The objects of the invention are met by an arrangement for setting a compression ratio of an internal combustion piston engine, which arrangement pro- vides a power transmission connection between a piston and a crank shaft of the engine when assembled, and which arrangement comprises a body part having a first end and a second end for attaching the body part at its ends to a respective housing and between the first and the second ends there is an eccentric sleeve arranged for attaching the arrangement to a housing of the connecting rod via the sleeve The arrangement further comprises a hydraulic rotation suppression system arranged to allow or suppress rotation of the eccentric sleeve in respect to the connecting rod, which hydraulic rotation suppression system comprises a hydraulic circuit having a valve member arranged to close or open the circuit, and a hydraulic fluid displacement part arranged to displace hydraulic fluid in the hydraulic circuit in interaction with the rotational position eccentric sleeve . It is characteristic to the invention that the displacement part is arranged to the eccentric sleeve as its outside radial extension and the arrangement is provided with an angular space co-operating with the extension on the outer surface of the eccentric sleeve, the cross sectional shape of which coincides with the cross sectional shape of the dis- placement part. [0012] The arrangement provides a simple and reliable manner of setting a compression ratio of an engine.

[0013] According to an embodiment of the invention the displacement part is ar- ranged in connection with the eccentric sleeve and it is arranged to co-operate with a hydraulic circuit so that the circuit ends are connected to opposite sides of the displacement part.

[0014] According to an embodiment of the invention the displacement part is ar- ranged to the eccentric sleeve as its radial extension.

[0015] According to an embodiment of the invention the valve member is arranged into the body part of the arrangement. [0016] According to an embodiment of the invention the body part is a piston pin having a first end and a second end for attaching the piston pin at its ends to the piston, and between the first and the second ends there is an eccentric sleeve arranged for attaching the arrangement to a housing of the connecting rod via the sleeve, and that the valve member is arranged into the piston pin.

[0017] According to an embodiment of the invention the valve member is a directional control valve.

[0018] According to an embodiment of the invention the directional control valve comprises at least three operational positions and in which a flow directing element arranged operable by lubrication oil as a control fluid so that applying of pressure of the lubrication oil acting through the control port to the flow directing element causes the flow directing element to change its position, and spring unit applying force to the flow directing element so that the force opposes the change of position, the spring unit comprises a spring system which provides a discontinuous^ increasing change of the spring force exerted by the spring unit.

[0019] According to an embodiment of the invention the change of spring force is arranged to commence after a first shifted position of the flow directing element in the control valve. [0020] According to an embodiment of the invention the spring system comprises at least two parallel springs.

[0021 ] According to an embodiment of the invention the first spring is arranged to apply force to the flow directing element at its each position in the control valve, and the second spring is arranged to initiate to apply force to the flow directing element after a first shifted position of the flow directing element.

[0022] According to an embodiment of the invention the first shifted position of the flow directing element is arranged to be at a position where the flow directing element is at its second operational position.

[0023] According to an embodiment of the invention the second spring is arranged to apply force at compressed state to the flow directing element at a position where the flow directing element is at its third operational position.

[0024] According to an embodiment of the invention the control valve comprises N operational position and the spring system comprises N-1 parallel springs. [0025] According to an embodiment of the invention each spring is arranged to initiate to apply force successively to the flow directing element commencing after successive shifted positions of the flow directing element.

[0026] According to an embodiment of the invention flow directing element is co- directional with the body part.

[0027] According to an embodiment of the invention hydraulic circuit is connecta- ble to a lubrication system on an engine when installed and arrangement is provided lubricant pressure booster unit arranged in connection with the lubrication system of the engine.

[0028] The present invention is suitable for changing compression ratio during the operation of the engine in general. By means of the invention the control of the setting a compression ratio is straightforward and technically reliable. Brief Description of Drawings

[0029] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in which

Figure 1 illustrates a schematically an internal combustion engine,

Figure 2 illustrate a cross sectional view ll-ll of figure 1 ,

Figure 3 illustrates an embodiment of the arrangement according to the invention, Figure 4 illustrates an embodiment of a valve member in the arrangement according to the invention,

Figure 5 illustrates a position of the flow directing element according to an embodiment of the invention,

Figure 6 illustrates a directional control valve according to an embodiment of the invention,

Figure 7 illustrates a directional control valve according to another embodiment of the invention,

Figure 8 illustrates the operation of the spring unit according to an embodiment of the invention,

Figure 9 illustrates another embodiment of the arrangement according to the invention and,

Figure 10 illustrates a piston pin arrangement according to the invention.

Detailed Description of Drawings [0030] Figure 1 shows extremely schematically an internal combustion piston engine 100 and one piston 102 thereof. In figure 2 there is shown a cross sectional view ll-ll of figure 1. The piston 102 is coupled with a crank shaft (not shown) of the engine by means of a connecting rod 105. Compression ratio of a piston engine is the ratio of the sum of compression volume and stroke volume to the com- pression volume. Thus, changing the effective distance of the top of the piston to the crank shaft pin changes the compression ratio. In figure 1 there is shown an arrangement 104 for setting a compression ratio of an internal combustion piston engine. [0031 ] The arrangement provides a power transmission connection between a piston 102 and a crank shaft of the engine. In this case the arrangement is at the piston end of the connecting rod but it may be also feasible to arrange it at the crank shaft end of the connecting rod 105.

[0032] The arrangement comprises a body part 106 which in the embodiment of figure 1 is a piston pin. For that reason the piston pin is referred to with a same reference number as the body part. The body part 106 is attached at its ends 106.1 , 106.2 to a respective housing, in this embodiment being part of in the pis- ton. Between the first and the second ends 106.1 , 106.2 there is an eccentric sleeve 108 arranged for attaching the arrangement 104 to housing in the connecting rod 105 via the sleeve 108. Even if not shown in the figure, there may be additional sleeves arranged between the shown elements in practise. [0033] The arrangement comprises a rotation suppression system 1 10 being a hydraulic suppression system. The hydraulic rotation suppression system 1 10 comprises a hydraulic circuit 1 12 arranged to allow or suppress rotation of the eccentric sleeve 108 in respect to the connecting rod. The hydraulic circuit is provided with a valve member 1 14 arranged to close or open the circuit as referred to by a valve unit 120 and also to determine the flow direction of the hydraulic fluid in the circuit as depicted by arrows 1 14' and 1 14".

[0034] The hydraulic fluid is advantageously lubrication oil of the engine. The hydraulic circuit is thus connected to lubrication system 122 of the engine 100 for supplying necessary make-up oil to the circuit in order to compensate any leakage. The lubrication system is shown here very schematically showing an oil sump 130 and an oil pump 132 of the system.

[0035] There is a displacement part 124 in connection with the eccentric sleeve 108 and it is arranged to co-operate with a hydraulic circuit 1 12 so that the circuit ends 1 12.1. 1 12.2 are connected to opposite sides of the displacement part 124. Thus the hydraulic fluid displacement part arranged to displace hydraulic fluid in the hydraulic circuit in interaction with the rotational position eccentric sleeve 108. [0036] In figures 1 and 2 the displacement part is arranged to the eccentric sleeve at its outer surface radially extending from the surface. The displacement part 124 also extends longitudinally. Respectively, the housing 126 belonging to the arrangement and being arranged around the eccentric sleeve is provided with an angular space128 along the outer surface of the eccentric sleeve. The housing 126 where the space is arranged may be integral part of the connecting rod or it may be a separate stationary assembled sleeve where the space is arranged. In the figures 1 and 2 the cross sectional shape of the space 128 part is rectangular and it coincides with the cross sectional shape of the displacement part. The fitting between the space and the displacement part is such that the displacement part is adequately sealed in respect to the surface of the space for displacing the hydrau- lie fluid in the space in interaction with the rotational position eccentric sleeve. There may be separate sealing elements arranged to improve the sealing effect.

[0037] Advantageously the space 128 extends angularly at least 180° region so that the rotational position of the eccentric sleeve may be changed between two extreme positions which provide the longest possible and the shortest possible effective distance of the top of the piston to the crank shaft pin of the engine.

[0038] The arrangement may be operated so that the valve member 1 14 is controlled to change the operational status of the arrangement. The arrangement may be at a state where the rotation of the eccentric sleeve 108 is suppressed by closing circuit 1 12 by the valve member 1 14. When the flow of the fluid in the circuit is suppressed the eccentric sleeve 108 may not rotate because the movement of the displacement part 124 is blocked by the closed hydraulic circuit 1 12. Although the eccentric sleeve may be blocked at any position, it is advantageous to block it at the extreme positions where the rotational forces to which the sleeve is subjected may be minimized due to the geometry of the arrangement.

[0039] The arrangement may be set to be at state where the rotation of the eccentric sleeve 108 is allowed to one, first direction only. Now the fluid in the circuit 1 12 is allowed to flow in one direction by controlling the valve member 1 14 accordingly. While the engine is running the gas and mass forces produce a rotating torque to the eccentric sleeve. Since the position of the eccentric sleeve is determined by the displacement part 124 and since the fluid in the circuit 1 12 is allowed to flow in one direction, the eccentric sleeve may rotate only in one direction. Changing the position of the sleeve from the first extreme position to the second one may take several strokes of the piston, but once reached the second extreme position may be maintained by activating the state where the rotation of the eccentric sleeve 108 is suppressed by closing circuit 1 12 by the valve member 1 14. Now the flow of the fluid in the circuit is suppressed and the eccentric sleeve 108 may not rotate.

[0040] Similarly, when the changing of the position of the sleeve from the second extreme position to the first one is desired, a state is activated where the rotation of the eccentric sleeve 108 is allowed to one, second direction only. Now the fluid in the circuit 1 12 is allowed to flow in the second direction by controlling the valve member 1 14 accordingly.

[0041 ] According to an embodiment of the invention, the prime mover to the change of the state i.e. the compression ratio is accomplished by gas and mass forces subjected to the piston and the direction of the movement is controlled with the arrangement.

[0042] In figure 3 there is shown another embodiment of the arrangement according to the invention which is otherwise similar to that shown in figure 1 but the displacement part 124 is arranged to the eccentric sleeve at its inner surface radially extending from the surface. Respectively, the piston pin 106 belonging to the arrangement is provided with an angular space128' along the outer surface of the piston pin. Even if not shown in the figure 3, there may be additional sleeves arranged between the shown elements in practise. [0043] In figure 4 there is shown an advantageous embodiment of the valve member 1 14. The valve member 1 14 is advantageously directional control valve 10 which is controlled by a control fluid. The control fluid is advantageously lubrication oil of the engine. The control valve comprises here three operational positions 12 and it has three valve ports 14. The control valve comprises a flow direct- ing element 18 which is operable by lubrication oil used as the control fluid. The control fluid may be supplied to the valve 10 via a control port 16. It is possible to apply pressure of control fluid to the flow directing element 18, which causes the flow directing element to change its position. The position of the flow directing element changes advantageously by linear translation. Advantageously the flow di- recting element is a piston element (142, Fig. 10) arranged in a cylinder (1 14, Fig. 10).

[0044] The flow directing element is arranged to have at least three different oper- ational positions 12 which provide different flow paths between the fluid ports 14. The hydraulic circuit 1 12 is connected to the directional control valve 10. This way the arrangement may be set to three different states where the rotation of the eccentric sleeve 108 is allowed to one direction only or the rotation is suppressed. In the figure the flow directing element is at its position suppressing the flow in the hydraulic circuit 1 12. The directional control valve 10 is connected to the circuit 1 12 at one side of the valve 10 the circuit is connected to a first port 14.1 and on other side of the valve to second and third ports 14.2, 14.3 via parallel branches 1 12.2, 122.3. Both the branches are provided with one-way valves 134, 136. The one-way valves are arranged to allow fluid flow in opposite directions in the branches. The flow directing element 18 such that in its first position the ports are closed. In the second position the first port 14.1 is in connection with the second port 14.2 so that the fluid may flow through the first branch 1 12.1. As the branch 1 12.1 is provided with the one-way valve 134 the fluid may flow in the circuit only in the direction depicted by the arrow 12.2. Further, the flow directing element 18 such that in its third position the first port 14.1 is in connection with the third port 14.3 so that the fluid may flow through the second branch 1 12.1 only. As the branch 1 12.2 is provided with the one-way valve 136 the fluid may flow in the circuit only in the direction depicted by the arrow 12.3 i.e. in opposite direction to the situation of the valve 10 being in its second position. The valve member is also provided with conduits 138 supplying necessary make-up oil to the circuit in order to compensate any leakage. The conduits are also provided with one-way valve preventing undesired escape of the fluid from the circuit 1 12.

[0045] The valve unit 1 14 further comprises a pressure booster unit 140 by means of which the required elevated pressure to be applied to the control port 16 of the control valve 10 may be produced. The elevated pressure is higher than pressure of lubrication oil during all operational circumstances of the engine. [0046] There is a spring unit 20 arranged to apply force to the flow directing element 18 so that the force opposes the change of the position caused by the pressure of the control fluid 6. In other words the control fluid exerts force to the flow directing element against the force of the spring unit 20.

[0047] The spring unit comprises a spring system 22, 24 which provides a discontinuous change of the force exerted by the spring unit 20 against the flow directing element. This way the pressure required to shift the flow directing element 18 after it has reached a predetermined position increases considerably compared to the required force by which the flow directing element was shifted to the position. Due to the considerable increase in the spring force setting the position accurately by means of the pressure of the control fluid is reliable.

[0048] In the embodiment of figure 4 the flow directing element 18 has three posi- tions: first, second and third position. The second position may be also referred to as the first shifted position and the third position as second shifted position since the first position is the nominal position at which the flow directing element 18 is maintained by the spring unit without control fluid pressure applied. Advantageously the change of spring force is arranged to commence just after the first shifted position of the flow directing element in relation to the direction to which the pressure fluid tends to move the flow directing element 18. This way due to the sudden increase of the spring force after the first shifted position the pressure of the control fluid need not be controlled too precisely but it may be set so that the movement to the first shifted position surely takes place without a risk of shifting the flow directing element too far over the correct position. In the figure 5 there is shown the first shifted position of the flow directing element 18, which results in the flow direction depicted by the arrow 12.2 in figure 4.

[0049] Additionally, in case the flow directed element is desired to be moved to its second shifted position pressure of the control fluid is increased by means of the pressure booster unit 140, to win the threshold force provided by the spring unit 20. If the pressure increases less than the threshold the flow directing element 18 will not move farther. When the threshold is overcome and even additional pressure to set the second spring 24 at compressed state the flow directing element is at a position where the flow directing element is at its third operational position, which results in the flow direction depicted by the arrow 12.3 in figure 4.

[0050] Preferably the spring system comprises at least two parallel springs 22, 24. In this case the change i.e. the increase of the spring force at the first shifted position is accomplished so that the second spring 24 is arranged to commence its effect on the flow directing element 18 while the first spring is arranged to apply force to the flow directing element 18 at its each position in the control valve. This may be accomplished so that the second spring is arranged of such length that it is mechanically coupled between the flow directing element 18 and a body part or other stopping means 26 against which the spring may be compressed only at and after the first shifted position. The springs are preferably helical springs and the second spring 24 is arranged inside or outside the first spring 22. [0051 ] It should also be understood that the spring may be of different type, figure 6 shows a directional control valve according to an embodiment of the invention where the second spring 24 of the spring unit 20 comprises a number of compression parts arranged between the coils of the first spring 22 having their dimension selected so that they will contact and effect on the compression of the first spring at the desired location of the flow directing element 18 as explained above. In figure 7 there is shown an embodiment in which the second spring 24 is a gas spring which is arranged to effect on the flow directing element 18 at the desired location as well for example by arranging the flow directing element and the spring unit in a common gas tight cylinder and allowing venting of the gas from the cylinder until the flow directing element has reached a desired location.

[0052] In figure 8 is illustrated the operation of the spring unit 20 according to an embodiment of the invention. The horizontal axis represents the position X of the flow directing element and thus the compression of the spring unit which in the embodiment of the figure 4 comprises two springs. The position X1 represents the first position of the flow directing element 18 at which it is at its nominal position. At this position the flow directing element 18 is maintained by the spring unit applying a force F1 against the flow directing element 18, without control fluid pressure applied. At the second position X2 the control fluid applies at least a force F2 to the fluid control element 18 compressing the first spring. Now, at the second location the second spring commences its effect providing a threshold F2-F2' to the needed force for changing the position of the flow directing element from the second position X2. As can be seen in the figure the force applied by the control fluid may be anything between F2 - F2' and still the flow directing element remains in the second position X2. Thus the control of the pressure of the control fluid is allowed to have some considerable operating window which makes it easier and less prone to disturbances. Only after the force F2' has exceeded the flow directing element starts to move so that the position X3 requires at least the force F3.

[0053] It is possible to obtain other operational controls with the control valve and in such case the control valve may comprise N pes of operational positions and hence the spring system comprises N-1 parallel springs. Each spring is arranged to initiate to apply force successively to the flow directing element commencing after a successive shifted position of the flow directing element. It is also clear that the flow directing element may provide various types of flow paths, other than those shown here, between the ports 14.

[0054] Figure 9 shows an arrangement 104 for setting a compression ratio of an internal combustion piston engine integrated into a piston pin for en internal combustion piston engine according to an embodiment of the invention.

[0055] The arrangement provides a power transmission connection between the piston 102 and the crank shaft of the engine. The arrangement comprises a body part 106 which is a piston pin. The piston pin 106 is attached at its ends 106.1 , 106.2 to a respective housing in the piston. Between the first and the second ends 106.1 , 106.2 there is an eccentric sleeve 108 arranged for attaching the arrangement 104 to housing in the connecting rod 105 via the sleeve 108. Even if not shown in the figure, also in this embodiment there may be additional sleeves ar- ranged between the shown elements in practise.

[0056] The arrangement comprises a rotation suppression system 1 10 being a hydraulic suppression system. The hydraulic rotation suppression system 1 10 is similar to that shown in figure 4 and it operates in similar manner. The hydraulic circuit 1 12 arranged to allow or suppress rotation of the eccentric sleeve in respect to the connecting rod. The valve member 1 14 is arranged in the piston pin. The pressure booster unit 140 may be arranged in a stationary part of the engine. The arrangement needs only one lubrication oil conduit to the piston pin through which lubrication of is conveyed also to the piston pin bearing surface(s). Even if according to the invention the pressure of the lubrication oil is elevated from normal lubrication level for changing the compression ratio as explained before, that does not compromise the lubrication. The oil conduit leading from the pressure booster unit to the arrangement is led via channels arranged to crank shaft and connecting rod to the piston. An embodiment of such valve member 1 14 and piston pin arrangement is shown in figure 10 in more detailed manner using the same reference number as is other figures for applicable elements. Preferably the valve member comprises a plunger or a piston part 142 arranged in a cylinder 144. The cylinder and the piston part are arranged co-directionally with the piston pin 106. The cylin- der is provided with longitudinally spaces openings serving as the ports 14.1 - 14.3. The piston part is provided with two recessions 146 circumscribing the piston. The recessions are dimensioned spaced so that each recession may extend between two adjacent ports providing a flow communication between them. The first end of the piston part is in connection with the control port 16 and the spring unit 20 is arranged to the opposite, second end thereof. The piston part 142, the cylinder 144, eccentric sleeve 108 and the piston pin 106 are provided with suitable elements, such as borings and/grooves to provide function of the valve member 1 14 shown in figure 4. [0057] While the invention has been described herein by means of examples in connection with what are, at present, considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the invention, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.

Claims

1 . Arrangement for setting a compression ratio of an internal combustion piston engine, which arrangement provides a power transmission connection be- tween a piston and a crank shaft of the engine when assembled, and which arrangement comprises a body part (106) having a first end (106.1 ) and a second end (14.2) for attaching the body part at its ends to a respective housing and between the first and the second ends there is an eccentric sleeve arranged for attaching the arrangement (104) to a housing of the connecting rod (105) via the sleeve, and the arrangement comprises a hydraulic rotation suppression system (1 10) arranged to allow or suppress rotation of the eccentric sleeve (108) in respect to the connecting rod, which hydraulic rotation suppression system comprises a hydraulic circuit (1 12) having a valve member (1 14) arranged to close or open the circuit, and a hydraulic fluid displacement part (124) arranged to displace hy- draulic fluid in the hydraulic circuit in interaction with the rotational position eccentric sleeve (108), characterized in that the displacement part is arranged to the eccentric sleeve (108) as its outside radial extension and the arrangement is provided with an angular space (128) co-operating with the extension on the outer surface of the eccentric sleeve (108), the cross sectional shape of which coincides with the cross sectional shape of the displacement part (124).

2. Arrangement according to claim 1 , characterized in that the displacement part (124) is arranged in connection with the eccentric sleeve (108) and it is arranged to co-operate with a hydraulic circuit (1 12) so that the circuit ends are connected to opposite sides of the displacement part (124).

3. Arrangement according to claim 1 , characterized in that the displacement part (124) is arranged to the eccentric sleeve (108) as its radial extension.

4. Arrangement according to claim 1 , characterized in that valve member (1 14) is arranged into the body part (106) of the arrangement.

5. Arrangement according to claim 4, characterized in that the body part (106) is a piston pin having a first end (106.1 ) and a second end (14.2) for attaching the piston pin at its ends to the piston (102), and between the first and the second ends there is an eccentric sleeve (108) arranged for attaching the arrange- ment (10) to a housing of the connecting rod (12) via the sleeve, and that the valve member is arranged into the piston pin.

6. Arrangement according to claim 5, characterized in that the valve member is a directional control valve, which directional control valve (10) comprises at least three operational positions (12) and in which a flow directing element arranged operable by lubrication oil as a control fluid so that applying of pressure of the lubrication oil acting through the control port (16) to the flow directing element causes the flow directing element to change its position, and spring unit (20) applying force to the flow directing element so that the force opposes the change of position, the spring unit (20) comprises a spring system (22, 24) which provides a discontinuously increasing change of the spring force exerted by the spring unit (20).

7. Arrangement according to claim 5, characterized in that the change of spring force is arranged to commence after a first shifted position of the flow di- recting element (18) in the control valve.

8. Arrangement according to claim 5, characterized in that the spring system comprises at least two parallel springs (22, 24).

9. Arrangement according to claim 5, characterized in that the first spring (22) is arranged to apply force to the flow directing element at its each position in the control valve, and the second spring (24) is arranged to initiate to apply force to the flow directing element after a first shifted position of the flow directing element (18).

10. Arrangement according to claim 5, characterized in that that the first shifted position of the flow directing element (18) is arranged to be at a position where the flow directing element is at its second operational position.

1 1 . Arrangement according to claim 5, characterized in that the second spring (24) is arranged to apply force at compressed state to the flow directing element at a position where the flow directing element (18) is at its third operational position.

12. Arrangement according to claim 5, characterized in that the control valve comprises N operational position and the spring system comprises N-1 parallel springs.

13. Arrangement according to claim 5, characterized in that that each spring is arranged to initiate to apply force successively to the flow directing element commencing after successive shifted positions of the flow directing element.

14. Arrangement according to claim 6, characterized in that hydraulic circuit (1 12) is connectable to a lubrication system (122) of an engine when installed and arrangement is provided lubricant pressure booster unit (140) arranged in connection with the lubrication system of the engine.