Drive arrangement for a camshaft fitted in the cylinder head of

Details Drive arrangement for a camshaft fitted in the cylinder head of Drive arrangement for a camshaft fitted in the cylinder head of

1991-11-06

1993-05-18

Cross, E. Rollins

Internal-combustion engines

Poppet valve operating mechanism

With means for varying timing

123 9031, 74568R, 74567, 464 1, 464 2, F01L 134, F15B 1500

Patent

active

052111415

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a drive arrangement for a camshaft mounted in the cylinder head of an internal combustion engine, corresponding to the introductory portion of claim 1.
In the case of a known drive arrangement of this type (German Auslegeschrift 36 16 234), the servo motor is disposed axially in front of the drive wheel in a machine housing cover. Due to this arrangement, the dimensions of the internal combustion engine in the longitudinal direction are increased. If the internal combustion engine is installed longitudinally in a motor vehicle, this leads to space problems, since a flat hood, which drops off towards the front, is desirable for aerodynamic reasons. It is therefore hardly possible to install such an internal combustion engine with variable valve control in an existing vehicle.
It is an object of the invention to provide a drive arrangement of the type, with which the problems described on installing the internal combustion engine in a motor vehicle are avoided.
Pursuant to the invention, this objective is accomplished owing to the fact that the servo motor is disposed adjacent to that end of the camshaft, which is averted from the drive wheel, and that the control element of the servo motor is connected with the switching component through a switching rod, which is put through the camshaft.
In the case of the inventive proposal, the servo motor can be accommodated without difficulties, since it is located at a place, at which the hood rises towards the windshield.
Preferably, the drive wheel and the camshaft are mounted independently of one another in the cylinder head, so that the structure is significantly simpler than that of the state of the art. In order to be able to compensate for alignment errors between the drive wheel and the camshaft, the two external tooth systems of the switching component are disposed on separate sections, which are connected together so that they cannot rotate relative to one another, but yet so that the angle between them can be varied.
An embodiment of the invention is described in the following, with reference to the drawings, in which
FIG. 1 shows a partial longitudinal section of a cylinder head of an internal combustion engine in a horizontal plane through a camshaft and
FIG. 2 shows a view of the subassembly comprising the switching element, the switching rod and the control element of the servo motor.
In FIG. 1, the cylinder head of a valve-controlled, reciprocating piston internal combustion engine, is labelled 1. In this internal combustion engine, a camshaft 3, which carries the cams 4, with which the inlet and/or outlet valves of the internal combustion engine, which are not shown, are operated, is mounted on bearing 2. Coaxially with the camshaft 3, a drive wheel 5, which is driven by the crankshaft of the internal combustion engine, is mounted in the cylinder head 1. A switching component 6, which has two axially adjacent external tooth systems 7 and 8, which include different angles with the longitudinal center line of the cam shaft 3, serves to transfer the drive from the drive wheel 5 to the camshaft 3. In the embodiment, the external tooth system 7 is constructed as a spur toothing and the external tooth system 8 as a helical gearing. However, the external tooth system 8 could also be constructed as the spur toothing and the external tooth system 7 as the helical gearing.
Finally, there is also the possibility of constructing the external tooth system 7 as well as the external tooth system 8 as a helical gearing, however with the opposite or a different inclination. The external tooth system 7 engages a corresponding internal tooth system 9 in the hollow hub 10 of the drive wheel 5 and the external tooth system 8 engages the corresponding internal tooth system 11 in a longitudinal borehole 12 of the camshaft 3. The switching component 6 can be shifted axially by a servo motor 13. The servo motor is disposed at the end of the camshaft 3 that is averted from the drive wheel 5 and, in the embodiment, has a hydraulic cylinder 14, which is

REFERENCES:
patent: 4747375 (1988-05-01), Williams
patent: 4754659 (1988-07-01), Rietsch
patent: 4787345 (1988-11-01), Thoma
patent: 4976229 (1990-12-01), Charles
patent: 5033323 (1991-07-01), Janson

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