Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Patent
1993-05-19
1994-04-26
Nelli, Raymond A.
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
123 9031, 464 2, 74568R, F01L 134
Patent
active
053057180
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control device for rotating a camshaft of an internal combustion engine.
More particularly, it relates to a hydraulic control device for rotating a camshaft of an internal combustion engine, which has a longitudinally displaceable couple member acted upon by pressure and having a first outer toothing engaging with an inner toothing of a sprocket wheel driven by the internal combustion engine and a second toothing engaging a toothing of the camshaft, wherein the pressure medium delivered by a pump is directed via an electromagnetic valve.
Hydraulic control devices of the above mentioned general type are known in the art. One of such hydraulic control devices is disclosed in the German reference DE-OS 32 47 916.
In such a known control device in particular the pump and the electromagnetic valve are arranged externally, which is relatively complicated, requires a large amount of space, and is very cumbersome in view of the necessary pressure medium connections.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a hydraulic control device of the above mentioned general type, which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a hydraulic control device in which a hydraulic body is flanged on at a widened end portion of the camshaft on which the sprocket wheel also sits, a radial piston pump with a plurality of pistons slides in approximately radially extending piston bores in the hydraulic body, the spherical caps of the pistons contact an inner ring of a ball bearing which is arranged in a stationary housing eccentrically relative to the axis of the camshaft, an outlet valve is connected to a pressure space of every piston bore and its outlet opens into the pressure space of the longitudinal bore hole which receives a single-action piston and extends in the hydraulic body, the pressure spaces closed by the valve housing of a pressure limiting valve controlling the valve housing, and the inlet side of the piston bores are fed by a pump, wherein the magnetic valve which controls the feed flow is arranged between the pump and the piston bores.
When the hydraulic control device is designed in accordance with the present invention, it has the advantage over the prior art of a very compact construction and a very simple installation in the internal combustion engine or its engine compartment. It operates with high precision and is also relatively simple to assemble.
In accordance with another feature of the present invention the pressure limiting valve at the pressure space has a diaphragm which is acted upon by pressure and controls a valve seat constructed at the plate.
The camshaft, the sprocket wheel and the hydraulic body can be connected by screws which penetrate through sleeves arranged in the sprocket wheel in longitudinal slots, and there are pressure medium connections in the screws from the piston bores via the electromagnetic valve to the pump.
The electromagnetic valve can be arranged in a bearing member supporting the camshaft and can receive a tappet connected with the armature so as to actuate the valve member and simultaneously control a connection from the pump to the outlet of the electromagnetic valve.
The sensor ring can be arranged on the rotating hydraulic body, a throttle can be provided in the inlet duct to the piston bores. The toothing pairs can be formed as a spiral toothing and a spur toothing, wherein the spiral toothing can be formed at the inner circumference of the sprocket wheel and the outer circumference of a widened portion of the couple member.
Finally, a restoring force can act in form of a pressure spring on the piston or can be applied by the spiral toothing acting on the piston and having an angle of approximately 30.degree.-45.degree..
The novel features which are considered as characteristic for the invention are
REFERENCES:
patent: 4787345 (1988-11-01), Thoma
patent: 5012773 (1991-05-01), Akasaka et al.
patent: 5189999 (1993-03-01), Thoma
patent: 5209194 (1993-05-01), Adachi et al.
patent: 5247914 (1993-09-01), Imai et al.
Lo Weilun
Nelli Raymond A.
Robert & Bosch GmbH
Striker Michael J.
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