Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-08-28
2001-11-20
Lo, Weilun (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090170
Reexamination Certificate
active
06318314
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device for setting the movement behavior of gas-exchange valves of an internal combustion engine having a camshaft. A control unit generates a setting signal which controls an adjustment of the camshaft. A pilot control system is additionally provided for additively correcting the setting signal.
An appliance for rotating a camshaft relative to the crankshaft in an internal combustion engine is known from German Patent DE 43 40 614 C2. The appliance has a control unit that generates a setting signal as a function of the deviation of an actual position of the camshaft from a required position. The setting signal is multiplicatively corrected by a correction factor that is determined as a function of a rotational speed and an oil temperature. Such appliances exhibit significant delay times, which reduce the maximum achievable control rate. It has been found, in practice, that the control unit can be parametrically organized either in such a way that a step in the required position is followed up only slowly or in such a way that there is a rapid follow-up to a step in the required position with the consequence of a small stability reserve. A rapid follow-up of steps in the required position is, however, necessary in order to also ensure comfortable operation of the internal combustion engine in transient operation with, at the same time, a low fuel consumption and high power.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device for setting the movement behavior of gas-exchange valves of an internal combustion engine which overcomes the above-mentioned disadvantages of the prior art devices of this general type, in which a comfortable operation of the internal combustion engine is also ensured in transient operation and with, at the same time, a low fuel consumption and high power.
With the foregoing and other objects in view there is provided, in accordance with the invention, a device for setting movement behavior of gas-exchange valves of an internal combustion engine having a camshaft. The device includes a setting device having a setting element to be connected to the camshaft and being a system subject to a delay time. A control unit is connected to the setting element and generates a setting signal received by and controlling the setting element for adjusting the camshaft. A pilot control system for additively correcting the setting signal is connected to the control unit. The pilot control system determines an estimated value for adjusting the camshaft without taking account of the delay time of the setting device. The pilot control system correcting the setting signal in dependence on the estimated value and a specified required value.
The solution presented by the invention is distinguished by the fact that the movement behavior of the gas-exchange valves can be adjusted very rapidly with surprising simplicity. Thus, the desired movement behavior of the gas-exchange valves can be ensured for each current operating condition of the internal combustion engine. In addition, the control unit only has to provide compensation for inaccuracies in the pilot control system.
In accordance with an added feature of the invention, the pilot control system corrects the setting signal in dependence on a load parameter, a rotational speed and an oil temperature.
In accordance with an additional feature of the invention, the control unit determines the setting signal in dependence on a measured value and a further estimated value for the adjustment of the camshaft which takes account of the delay time.
In accordance with another feature of the invention, an integrator is connected to the control device and integrates the setting signal and only outputs an integrated setting signal to the setting element if the integrated setting signal exceeds a specified threshold value.
In accordance with another added feature of the invention, the setting signal is determined cyclically from a cycle time, and synchronously with a rotational speed of the internal combustion engine. A physical model of the setting device being provided by which the estimated value is determined, taking account of the cycle time.
In accordance with a concomitant feature of the invention, the estimated value is determined in dependence on the rotational speed and an adjustment rate of the camshaft.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for setting the movement behavior of gas-exchange valves of an internal combustion engine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
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Patent Abstracts of Japan No. 60-190610 (Thoshinaru), dated Sep. 28, 1985.
Otto Erhard
Rosel Gerd
Schulte Wolfgang
Zhang Hong
Greenberg Laurence A.
Lerner Herbert L.
Lo Weilun
Siemens Aktiengesellschaft
Stemer Werner H.
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