Actuating device for changeover valves of an internal combustion engine and internal combustion engine

Abstract

An actuating device (11) is provided for changeover valves (10) of an internal combustion engine having an adjustable compression ratio. Each changeover valve (10) is used to control a hydraulic oil flow in hydraulic chambers of an eccentric adjusting device of a respective connecting rod (1) of the internal combustion engine. Each changeover valve (10) has a pick-off element (12) that can be actuated by the actuating device (11). The actuating device (11) has a selector fork (13) for each changeover valve (10) and hence for each pick-off element (12) to be actuated. The selector forks are secured on a support structure (14) and can be moved from a first selection position into a second selection position against the restoring force of a return element (22), and wherein the restoring force of the return element (22) moves the selector forks (13) automatically in the direction of the first selection position.

Claims

1. An actuating device for changeover valves of an internal combustion engine having an adjustable compression ratio, each changeover valve being used to control a hydraulic oil flow in hydraulic chambers of an eccentric adjusting device of a respective connecting rod of the internal combustion engine, each changeover valve having a pick-off means that can be actuated by the actuating device, the actuating device comprising: a selector fork for each changeover valve and for each pick-off means to be actuated, the selector forks being secured on at least one support structure, and being moveable from a first selection position into a second selection position against a restoring force of at least one return element, wherein the restoring force of the at least one return element moves the selector forks automatically in a direction of the first selection position.

2. The actuating device of claim 1, wherein the at least one return element comprises a single return element and wherein all of the selector forks are secured on the supporting structure so that all of the selector forks can be moved jointly from the first selection position into the second selection position against the restoring force of the return element, wherein the restoring force of the return element moves all the selector forks jointly and automatically in the direction of the first selection position.

3. The actuating device of claim 2, wherein all the selector forks are secured on a common guide element of the support structure that can be moved by the guide element.

4. The actuating device of claim 2, wherein the support structure of the actuating device has a mounting frame and at least one guide element that can be moved relative to the mounting frame, the selector forks being secured on the respective guide element and can be moved relative to the mounting frame by the respective guide element.

5. The actuating device of claim 4, wherein the return element is supported on the mounting frame of the support structure and on one of the guide elements or on the guide element of the support structure.

6. The actuating device of claim 4, wherein the return element is supported on one of the guide elements or on the guide element of the support structure and on or in the crankcase of the internal combustion engine.

7. The actuating device of claim 1, wherein one actuator moves all the selector forks jointly from the first selection position into the second selection position against the restoring force of the return element.

8. The actuating device of claim 7, wherein, when the actuator is active, the actuator moves the selector forks from the first selection position into the second selection position, and, when the actuator is inactive, the return element pushes the selector forks out of the second selection position into the first selection position.

9. The actuating device of claim 1, wherein the return element is a spring.

10. An internal combustion engine that has an adjustable compression ratio, the internal combustion engine having a plurality of connecting rods, each of the connecting rods having a hydraulically adjustable eccentric adjusting device arranged in a small end bearing eye and/or a big end bearing eye for adjusting an effective connecting rod length (l.sub.eff) of the respective small end bearing eye, wherein an adjusting travel of the eccentric adjusting device is controlled by a changeover valve, the changeover valves being actuated by the actuating device of claim 1.

Description

BRIEF DESCRIPTION

(1) FIG. 1 shows a connecting rod having an eccentric adjusting device and a changeover valve.

(2) FIG. 2 shows an actuating device for changeover valves of the connecting rods.

(3) FIG. 3 shows an actuating device according to the invention.

(4) FIG. 4 shows another actuating device according to the invention.

DETAILED DESCRIPTION

(5) FIG. 1 shows a connecting rod 1 of an internal combustion engine having an adjustable compression ratio as per an illustrative embodiment. The connecting rod 1 has a connecting rod main body 7 with a small end bearing eye 2 and a big end bearing eye 3.

(6) The small end bearing eye 2 is used to attach the respective connecting rod 1 to a cylinder piston (not shown) of a respective cylinder of the internal combustion engine. The big end bearing eye 3 is used to attach the respective connecting rod 1 to a crankshaft (not shown) of the internal combustion engine.

(7) The connecting rod 1 in FIG. 1 has an eccentric adjusting device 6, at least one section of which is arranged in the small end bearing eye 2 and that is preferably hydraulically adjustable. The eccentric adjusting device 6 has a piston pin bore arranged eccentrically with respect to a center 8 of the small end bearing eye 2 and has a center. The bore accommodates a piston pin (not shown). The respective connecting rod 1 is coupled to the cylinder piston of the respective cylinder by the piston pin.

(8) The eccentric adjusting device 6 is used to adjust an effective connecting rod length l.sub.eff of the connecting rod 1. Turning of the adjustable eccentric adjusting device 6 is initiated by the action of inertia forces and load forces of the internal combustion engine that act on the eccentric adjusting device 6 during an operating cycle of the internal combustion engine. During an operating cycle, the directions of action of the forces acting on the eccentric adjusting device 6 change continuously. The rotary movement or adjusting movement is assisted by pistons acted upon by hydraulic or engine oil that are integrated in the connecting rod arrangement 1 and are guided in hydraulic chambers, or the pistons prevent return of the eccentric adjusting device 6 due to varying directions of action of force of the forces acting on the eccentric adjusting device 6.

(9) The pistons of the eccentric adjusting device 6 are connected operatively on both sides to an eccentric body 9 of the eccentric adjusting device 6 by eccentric rods 4, 5. The eccentric adjusting device 6 can have the pistons, the eccentric rods 4, 5 and the eccentric body 9. The pistons of the eccentric adjusting device 6 are supplied with hydraulic fluid from the big end bearing eye 3 by hydraulic fluid lines (not shown in FIG. 1) via check valves (not shown in FIG. 1). The check valves prevent the hydraulic fluid from flowing back out of the piston volumes of the pistons into the hydraulic fluid lines and into the interior of the internal combustion engine.

(10) A changeover valve 10 is accommodated in a bore in the respective connecting rod 1.

(11) The hydraulic chambers of the eccentric adjusting device 6 of the respective connecting rod 1 are in contact via hydraulic fluid lines with the bore that accommodates the changeover valve 10. The selection position of the changeover valve 10 determines which of the hydraulic chambers is filled with hydraulic oil and which of the hydraulic chambers is emptied, wherein the adjusting direction or turning direction of the eccentric adjusting device 6 depends thereon.

(12) The respective changeover valve 10 of the respective connecting rod 1 has a pick-off means 12 and can be actuated by an actuating device acting on the pick-off means 12. Details of the changeover valve 10 of the respective connecting rod 1 and of the pick-off means 12 of the respective changeover valve 10 are familiar to the person skilled in the art referred to from DE 10 2012 112 461 A1, for example.

(13) The invention relates to an actuating device 11 for such an internal combustion engine having a compression ratio that can be set in a variable manner, namely an actuating device 11 that is used to actuate the pick-off means 12 of the changeover valves 10 of a plurality of connecting rods 1.

(14) An actuating device 11 for actuating a plurality of changeover valves 10 of an internal combustion engine having an adjustable compression ratio has a plurality of selector forks 13. Each selector fork 13 interacts with a pick-off means 12 of a respective changeover valve 10 to be actuated. All of the selector forks 13 preferably are secured on a common support structure 14.

(15) The support structure 14 of the actuating device 11 has a mounting frame 15 and a guide element 16 that preferably is common to all of the selector forks 13 in the illustrated embodiment. The guide element 16 can be moved relative to the mounting frame 15. In the illustrated embodiment, the guide element 16 has two guide rails 17, 18 that extend parallel to one another and are connected firmly to one another by a connecting web 19. Selector forks 13 are secured on each guide rail 17, 18 of the guide element 16. The entire actuating device 11 can be mounted on the crankcase (not shown) of the internal combustion engine by the mounting frame 15, namely by assembly screws (not shown), that extend through assembly openings 20 in the mounting frame 15.

(16) The guide element 16 of the actuating device 11, on which the selector forks 13 are secured, can be moved relative to the mounting frame 15 in the direction of the double arrow 21. This movement of the selector forks 13 of the actuating device 11 relative to the mounting frame 15 enables the pick-off means 12 of the respective changeover valve 10 to be actuated when the changeover valve 10 integrated into the respective connecting rod 1 of the respective cylinder has moved into the region of the respective selector fork 13 of the actuating device 15 during an operating cycle of a cylinder.

(17) The selector forks 13 of the actuating device 11 can be moved jointly with the aid of the guide element 16 of the support structure 14 on which the selector forks 13 are secured. The guide element 16 is common to all of the selector forks 13 in the illustrated embodiment, and can be moved relative to the mounting frame 15 of the support structure 14 and hence relative to the pick-off means 12 of the changeover valves 10 between a first selection position and a second selection position of the selector forks 13.

(18) A defined selection position of the changeover valves 10 of the connecting rods 1 of the internal combustion engine having an adjustable compression ratio can be set in the respective selection position by the selector forks 13 of the actuating device 11.

(19) The movement of the selector forks 13 of the actuating device 11 from the first selection position into the second selection position is accomplished with the aid of an actuator (not shown). All of the selector forks 13 can be moved jointly from the first selection position into the second selection position against the restoring force of a return element 22 that preferably is common to all the selector forks 13 and preferably is designed as a spring element. The restoring force of the return element 22 pushes all of the selector forks 13 jointly and automatically out of the second selection position in the direction of the first selection position when the actuator is not active.

(20) The invention is described below for the case of a return element 22 designed as a spring, although other return elements can also be used.

(21) The actuator that is active moves all selector forks 13 jointly from the first selection position to the second selection position against the spring force of the spring 22.

(22) The spring 22 pushes all selector forks 13 of the actuating device 11 jointly out of the second position into the first selection position when the actuator is inactive.

(23) In the embodiment in FIG. 3, the spring 22 engages on the mounting frame 15 of the support structure 14 and on the guide element 16 of the support structure 14. In this case, a first end of the spring 22 is supported on the mounting frame 15 and a second end of the spring 22 is supported on the guide element 16.

(24) FIG. 4 shows an embodiment of an actuating device 11 in which the spring element 22 is supported on the guide element 16 of the support structure 15 and on or in the crankcase of the internal combustion engine. The guide element is common to all the selector forks in the illustrated embodiment shown. A counterbearing 23 for the spring element 22 that is formed in or on the crankcase of the internal combustion engine is shown in FIG. 4.

(25) The actuating device 11 according to the invention is of simple construction and allows reliable movement of the selector forks 13 between the first selection position and the second selection position. When the actuator is active or energized, it transfers all the selector forks 13 jointly from the selection position into the second selection position, more specifically against the spring force of the respective spring element 22. The spring force of the spring element 22 pushes the selector forks 13 jointly in the direction of the first selection position. When the actuator is inactive or deenergized, e.g. owing to deliberate deactivation or owing to unintentional deactivation due to a power failure, the spring force of the spring element 22 pushes all the selector forks 13 jointly and automatically into the first selection position, with the result that a defined selection position for the selector forks 13 is ensured.

(26) The actuator needs to be energized only to hold the second selection position. Energization is not required for the second selection position. It is thereby possible to reduce the energy requirement for actuation.

(27) The actuator (not shown) which moves the selector forks 13 from the first selection position into the second selection position against the restoring force of the return element 22 is preferably an electric servo motor.

(28) The invention furthermore relates to an internal combustion engine having an adjustable compression ratio which comprises an actuating device 11 of this kind.

(29) Although an actuating device having a supporting structure common to all the selector forks and having a guide element common to all the selector forks and having a return element common to all the selector forks is preferred, it is also possible for the actuating device to have a plurality of coupled support structures and/or a plurality of coupled guide elements and/or a plurality of return elements. The coupling of the support structures and/or guide elements can be accomplished by means of corresponding coupling members or by means of deflection gears.