Valve adjustment mechanism for internal combustion engine

Abstract

A valve-adjusting mechanism for an internal combustion engine in which a drive shaft is constructed as reciprocating crankshaft actuating a connecting rod pivotally connected to the crankshaft so as to move to and fro between a fixed support wall and a pivotally supported wedge-shaped adjusting member extending at an acute angle with respect to the support wall; as a result of the wedging action, the adjusting member thereby carries out an up and down movement which is transmitted onto the valve by way of its valve stem.

Description

The present invention relates to a valve-adjusting mechanism for internal combustion engines, consisting of a drive shaft, a mechanism for converting the rotary movement into an up and down movement actuating the valve and of a mechanism for changing the valve lift in dependence on the rotational speed and the load of the internal combustion engine.

A valve control mechanism for internal combustion engines is known in the art (German Gebrauchsmuster No. 7,005,077), which includes a mechanism for converting the rotary movement of a drive shaft into a rocking or pivoting movement actuating the valve and a mechanism for changing the valve lift as a function of rotational speed and load of the internal combustion engine. This prior art installation consists primarily of a pivotally supported rocking lever extending over a wide area of the cylinder head cover. The arrangement of the pivot shaft as well as in particular of the relatively large rocker arm, however, are inconsistent with the aim to build relatively inexpensive and space-saving internal combustion engines.

It has also been proposed to set into pivot movements by means of a drive shaft a pivotally connected valve rocker which is supported with a curve-shaped back portion against an adjustable support plate and thus swingingly acts as double-armed lever with the other end on the valve stem whereby by adjustment of a support plate, the transmission ratio of the valve rocker and therewith of the valve lift can be changed. Notwithstanding the good and nearly symmetrical valve lift, this prior art installation includes parts which are subjected to an increased wear under the influence of inertia forces.

The aim of the present invention therefore resides in avoiding the described disadvantages.

The underlying problems are solved according to the present invention in a first embodiment in that the drive shaft is constructed as crankshaft which reciprocates a pivotally connected connecting rod between a stationary support wall and pivotally supported, wedge-shaped adjusting member extending at an acute angle thereto, whereby the adjusting member carries out an up and down movement as a result of the wedging effect and transmits the same onto the valve.

According to a further feature of the present invention, the installation for changing the valve lift may be so constructed that by displacement of the wedge-shaped adjusting member, the stroke and the opening period of the valve is changed without the fact that the position of the axis of symmetry for the up and down movement changes along in the control diagram.

Furthermore, the valve adjustment according to the present invention may be so constructed that for the displacement of the wedge-shaped adjusting member an essentially axially displaceable adjusting member is provided. In order to keep within acceptable limits the wear which occurs under the pressure of the valve spring by the parts sliding one upon the other, the connecting rod as well as the wedge-shaped adjusting member may be each equipped with a roller.

Furthermore, the support wall may be arranged adjustable to compensate for the play or the tolerances conditioned on manufacture and may also be covered or coated along the contact surface with respect to the reciprocating connecting rod with a noise-absorbing wear-resistant layer of any suitable known material.

The valve adjusting mechanism so far described may be additionally improved according to another embodiment of the present invention so that it can be readily assembled and manufactured relatively inexpensively. Additionally, the parts thereof should not be subjected to any significant wear.

This problem is solved according to the present invention in that the connecting rod during the to and fro movement is supported, on the one hand, by means of a segment-like part against the fixed support wall. This entails the advantage that the roller may roll off freely along the curved surface of the adjusting member.

According to another feature of the present invention, the adjusting member which is constructed ball-shaped at one end and is supported in a piston, may be held by a spring against an eccentric bolt, and an adjustable valve cap may engage in the slot and guide the valve-adjusting member.

Furthermore, the eccentric bolt may have a cylindrical eccentric surface and the effective working surface of the eccentric bolt may be disposed within the external contours of the bearing pin.

Accordingly, it is an object of the present invention to provide a valve-adjusting mechanism for internal combustion engines which avoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a valve-adjusting mechanism for internal combustion engines which is relatively inexpensive and enables a space-saving internal combustion engine construction.

A further object of the present invention resides in a valve-adjusting mechanism for internal combustion engines which far-reachingly reduces the wear of the various parts thereof, especially those subjected to the influence of inertia and spring forces.

Still a further object of the present invention resides in a valve-adjusting mechanism of the type described above which enables an adjustment of the stroke and opening period of the valve without changing the position of the axis of symmetry for the upward and downward movement in the control diagram.

Another object of the present invention resides in a valve-adjusting mechanism for the type described above which keeps the wear within acceptable limits, especially among those parts which slide one upon the other under the force of the valve spring.

A further object of the present invention resides in a valve-adjusting mechanism which permits a ready compensation of play and/or manufacturing inaccuracies.

Still a further object of the present invention resides in a valve-adjusting mechanism which can be readily assembled and installed with the use of parts that can be manufactured relatively inexpensively, avoiding at the same time excessive wear of any part thereof.

These and further objects, features, and advantages of the present invention will become more apparent from the following description, when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein:

Fig. 1 is a cross-sectional view through a valve-adjusting mechanism with a wedge-shaped adjusting member in accordance with the present invention; and

FIG. 2 is a cross-sectional view through a modified embodiment of a valve-adjusting mechanism in accordance with the present invention.

Referring now to the drawing, and more particularly to FIG. 1, in the valve-adjusting mechanism illustrated in this figure a crankshaft 2 is rotatably supported in the cylinder head 1; a connecting rod 4 is pivotally connected on the crank 3 of the crankshaft 2. The connecting rod 4 carries a roller 5 which as a result of the crank movement between a fixed support wall 6 and a pivotally supported, wedge-shaped adjusting member 7 extending at an acute angle with respect thereto, is moved to and fro along the axis of symmetry X--X. The adjusting member 7 is supported in the adjusting mechanism 9 by means of a pivot shaft 8 and carries at the free end 10 a roller 11 which acts on the valve stem 12 against the force of the valve spring 13. The adjusting element 9 is controlled in dependence on the load and rotational speed of the internal combustion engine by known conventional means (not shown), and more specifically essentially by an axial displacement thereof. Since such adjusting means are known in the art and form no part of the present invention, a detailed description thereof is dispensed with herein. The support wall 6 may be covered or coated with a noise-absorbing wear-resistant layer 15 of any conventional material along the contact surface 14 with respect to the reciprocating connecting rod 4.

The reciprocating connecting rod 4 which is reciprocated between the fixed support wall 6 and the wedge-shaped pivotally supported adjusting member 7 forces the valve-adjusting member 7 together with the roller 11 against the valve stem 12 when the roller 5 moves into the acute angle .alpha. formed by the support wall 6 and the adjusting member 7, and thereby opens the valve 16. During the return movement of the roller 5 by the connecting rod 4, the valve closes with the aid of the force of the valve spring 13 when the roller 5 has reached the portion 17 of the adjusting member 7 extending parallel to the support wall 6. Depending on the control of the adjusting member 7 by the adjusting element 9, the stroke and the opening period of the valve 16 is changed without changing along the position of the axis of symmetry for the up and down movement in the control diagram.

In the embodiment illustrated in FIG. 2, a crankshaft 102 is rotatably supported in the housing 101; a connecting rod 104 is pivotally connected to the crank 103 of the crankshaft 102. The connecting rod 104 is supported by means of a segment-like shaped part 105 against a locally fixed support wall 106, whereas a roller 107 is provided opposite thereto which during the to and fro movement actuated by the crank 103 rolls off along a curved cam surface 108 of an adjusting member 109. The adjusting member 109 is constructed spherically or ball-shaped at one end 110 and is supported in a piston 111. A spring 112 holds the adjusting member 109 together with the piston 111 against an eccentric bolt 113. A roller 115 is provided in a slot 114 of the adjusting member 109, which acts on an adjustable valve cap 116 which, in its turn, engages in the slot 114 and guides the adjusting member 109. The adjusting cap 116 is connected with the valve 117.

The eccentric bolt 113 includes a cylindrical eccentric surface 118 whose effective working surface is disposed inside of the external contours 119 of the bearing pin 120. Depending on the control of the adjusting element 119 by rotation of the eccentric bolt 113 and displacement of the piston 111, the stroke and opening angle of the valve 117 is changed.

The support wall 6 and/or 106 may be adjustable by conventional means to compensate for wear.

While I have shown and described only two embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

Claims

What I claim is:

1. A valve-adjusting mechanism for internal combustion engines which includes a drive shaft, a means for converting the rotary movement of the drive shaft into an up and down movement actuating a valve, and control means for changing the valve lift in dependence on at least one of rotational speed and load of an internal combustion engine, characterized in that the drive shaft, to provide the converting means, is constructed as a crankshaft reciprocating a connecting rod pivotally connected thereto between a fixed support wall means and a pivotally supported wedge-shaped adjusting means extending at an acute angle to the fixed support wall means so that the adjusting means carries out an up and down movement as a result of the wedging effect and is operative to transmit the same onto the valve.

2. A valve-adjusting mechanism according to claim 1, characterized in that the control means changes the valve lift as a function of both rotational speed and load of an internal combustion engine.

3. A valve-adjusting mechanism according to claim 1, characterized in that the stroke and opening period of the valve is changed by the displacement of the wedge-shaped adjusting means without changing the position of the axis of symmetry for the up and down movement in the control diagram.

4. A valve-adjusting mechanism according to claim 3, characterized in that an essentially axially displaceable adjusting member forming part of the control means is provided for the displacement of the wedge-shaped adjusting means.

5. A valve-adjusting mechanism according to claim 4, characterized in that the adjusting means carries a roller at its end acting on the valve.

6. A valve-adjusting mechanism according to claim 5, characterized in that the connecting rod carries a roller which is arranged between the fixed support wall means and the wedge-shaped adjusting means.

7. A valve-adjusting mechanism according to claim 6, characterized in that the support wall means is lined along its contact surface with respect to the reciprocating connecting rod with a noise-absorbing wear-resistant layer.

8. A valve-adjusting mechanism according to claim 7, characterized in that the support wall means is adjustable for purposes of compensating the play.

9. A valve-adjusting mechanism according to claim 8, characterized in that the control means changes the valve lift as a function of both rotational speed and load of an internal combustion engine.

10. A valve-adjusting mechanism according to claim 1, characterized in that an essentially axially displaceable adjusting member forming part of the control means is provided for the displacement of the wedge-shaped adjusting means.

11. A valve-adjusting mechanism according to claim 1, characterized in that the adjusting means carries a roller at its end acting on the valve.

12. A valve-adjusting mechanism according to claim 11, characterized in that the connecting rod carries a roller which is arranged between the fixed support wall means and the wedge-shaped adjusting means.

13. A valve-adjusting mechanism according to claim 1, characterized in that the support wall means is lined along its contact surface with respect to the reciprocating connecting rod with a noise-absorbing wear-resistant layer.

14. A valve-adjusting mechanism according to claim 1, characterized in that the support wall means is adjustable for purposes of compenating the play.

15. A valve-adjusting mechanism according to claim 1, characterized in that the connecting rod carries a roller which is arranged between the fixed support wall means and the wedge-shaped adjusting means.

16. A valve-adjusting mechanism according to claim 3, characterized in that the connecting rod includes a segment-like part, the connecting rod being supported during its to and fro movement, on the one hand, with its segment-like part against the fixed support wall means.

17. A valve-adjusting mechanism according to claim 16, with a roller supported in a slot of the adjusting member acting on a valve stem of the valve, characterized in that the adjusting means which is constructed ball-like at one end and supported in a piston means, is held by a spring against an eccentric bolt means.

18. A valve-adjusting mechanism according to claim 17, characterized in that an adjustable valve cap engages in the slot and guides the adjusting means.

19. A valve-adjusting mechanism according to claim 18, with a bearing pin, characterized in that the eccentric bolt means includes a substantially cylindrical eccentric surface and the effective working surface of the eccentric bolt means is disposed within the external contours of the bearing pin.

20. A valve-adjusting mechanism according to claim 1, characterized in that the connecting rod includes a segment-like part, the connecting rod being supported during its to and fro movement, on the one hand, with its segment-like part against the fixed support wall means.

21. A valve-adjusting mechanism according to claim 1, with a roller supported in a slot of the adjusting member acting on a valve stem of the valve, characterized in that the adjusting means which is constructed ball-like at one end and supported in a piston means, is held by a spring against an eccentric bolt means.

22. A valve-adjusting mechanism according to claim 21, characterized in that an adjustable valve cap engages in the slot and guides the adjusting means.

23. A valve-adjusting mechanism according to claim 21, with a bearing pin, characterized in that the eccentric bolt means includes a substantially cylindrical eccentric surface and the effective working surface of the eccentric bolt means is disposed within the external contours of the bearing pin.

24. An internal combustion engine comprising: a cylinder head means, a valve means disposed in said cylinder head means, a crankshaft means rotatably supported in said cylinder head means, means for converting the rotary movement of said crankshaft into a reciprocating movement for actuating the valve means, control means for changing the lift of the valve means in dependence upon at least one of rotational speed and load of the internal combustion engine, a support means disposed on said cylinder head, a pivotally mounted wedge-shaped adjusting means for adjusting said valve means, said valve means extending at an acute angle to said support means, said converting means including a connecting rod pivotally connected to said crankshaft means and reciprocable between said support means and said adjusting means whereby said adjusting means carries out a reciprocating movement as a result of the wedge-shape thereof and transmit the reciprocating movement to said valve means.

25. An internal combustion engine according to claim 24, wherein said control means changes the valve lift as a function of both rotational speed and load of the internal combustion engine.

26. An internal combustion engine according to claim 24, wherein said control means includes an essentially axially displaceable adjusting member for displacing said wedge-shaped adjusting means.

27. An internal combustion engine according to claim 26, wherein a roller means is provided on an end of said adjusting means acting on said valve means.

28. An internal combustion engine according to claim 27, wherein a roller means is provided on said connecting rod between said support means and said wedge-shaped adjusting means.

29. An internal combustion engine according to claim 28, wherein a noise-absorbing wear-resistant layer is provided on said support means along a surface thereof which contacts the reciprocating connecting rod.

30. An internal combustion engine according to claim 29, wherein means are provided for adjusting said support means to compensate for play in said valve means.

31. An internal combustion engine according to claim 24, wherein said connecting rod includes a segment-shaped portion engaging said support means during the reciprocating movement of said connecting rod.

32. An internal combustion engine according to claim 31, wherein said valve means includes a valve stem, said adjusting means includes a slot having disposed therein a roller means acting on said valve stem and a ball-shaped portion provided at one end thereof, a piston means is provided for supporting said ball-shaped portion and wherein an eccentric bolt means is provided, said adjusting means being biased against said eccentric bolt means by a spring means.

33. An internal combustion engine according to claim 32, whherein an adjustable valve cap means is disposed in said slot and guides said adjusting means.

34. An internal combustion engine according to claim 33, wherein a bearing pin is provided, said eccentric bolt means includes a substantially cylindrical eccentric surface and the effective working surface of the eccentric bolt means is disposed within the external contours of said bearing pin.

35. An internal combustion engine according to claim 24, wherein said valve means includes a valve stem, said adjusting means includes a slot having disposed therein a roller means acting on said valve stem and a ball-shaped portion provided at one end thereof, a piston means is provided for supporting said ball-shaped portion, and wherein an eccentric bolt means is provided, said adjusting means being biased against said eccentric bolt means by a spring means.

36. An internal combustion engine according to claim 35, wherein an adjustable valve cap means is disposed in said slot and guides said adjusting means.

37. An internal combustion engine according to claim 35, wherein a bearing pin is provided, said eccentric bolt means includes a substantially cylindrical eccentric surface and the effective working surface of said eccentric bolt means is disposed within the external contours of said bearing pin.

38. An internal combustion engine according to claim 24, wherein a noise-absorbing wear-resistant layer is provided on said support means along a surface thereof which contacts the reciprocating connecting rod.

39. An internal combustion engine according to claim 24, wherein a roller means is provided on said connecting rod between said support means and said wedge-shaped adjusting means.

40. An internal combustion engine according to claim 24, wherein a roller means is provided on an end of said adjusting means acting on said valve means.