Fluid handling – Systems – Supply and exhaust
Reexamination Certificate
2000-03-02
2001-06-19
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Supply and exhaust
C137S596200
Reexamination Certificate
active
06247494
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
This invention relates to a control valve device for a hydraulic user. More specifically, the invention relates to an electrically actuated control valve that has a sliding spool to control the connection of at least one user channel with a delivery and a reservoir channel, a shutoff valve in the user channel, which shuts off a return flow from the user to the control valve and a pilot valve to actuate the shutoff valve.
2. Background Information
Control valve devices are often used to actuate single-action or double-action users. On each of the user channels that lead from the sliding spool to the user, these devices have a shutoff valve that can be controlled by a pilot control valve for the leak-free isolation of the user. The shutoff valves are check valves that open toward the user and are generally spring-loaded and can be moved by the pilot valve into the open position to make possible a return flow from the user to the sliding spool if, as a result of a corresponding deflection of the sliding spool, the user channel is in communication with the reservoir channel. In this case, the pilot valves are also spring-loaded check valves and can be actuated by an actuator element, e.g., an actuator pin, to move them into the open position. In the open position, a connection is created between the control pressure compartment of the shutoff valve, which is in communication with the user and the reservoir channel so that the shutoff valve is moved into the open position by the pressure of the user. This makes possible a flow of hydraulic fluid from the user via the open shutoff valve and the sliding spool to the reservoir.
DE-OS 20 32 107 describes a similar control valve device of the prior art with a mechanically actuated control valve that is a sliding spool. In this device, the pilot control valves can be actuated by actuator pins moved into the open position. The actuator pins are in communication with diagonal, conical-shaped control surfaces formed on the sliding spool. When there is an axial deflection of the sliding spool, the pilot control valve can thus be opened by the actuator pin. With a mechanical actuation of the pilot control valves by a diagonal control surface formed on the sliding spool, a transverse force is exerted on the actuator pin, which in turn produces friction. As a result, the control valve device of this type is sluggish and subject to wear caused by friction. Consequently, with a control valve device of this type, a high actuation force is required to move the sliding spool and to actuate the pilot control valve.
The object of this invention is to make available a control valve device of the type described above with an electrically actuated control valve, which has a low actuation force to move the sliding spool and to actuate the pilot control valve.
SUMMARY OF THE INVENTION
The invention actuates the sliding spool and the actuator element through a gear train, the input element of which is effectively connected with an electrical drive apparatus. The output element of the gear train is in a driving connection with the sliding spool, and is effectively connected with the actuator element of the pilot control valve.
The invention provides a single-stage gear train that includes the input element and the output element. The input element is connected with the electrical drive device. The output element is provided for the actuation of the sliding spool and of the actuator element of the pilot control valve. The actuation of the sliding spool and of the actuator element is accomplished by the output element of the gear train.
The control valve device of the invention has the following series of advantages.
With a gear train of the invention, it becomes possible to easily move the actuator element so that any transverse forces, and thus friction on the actuator element, are eliminated. The result is a low actuation force of the control valve device to move the sliding spool and the actuator element.
Furthermore, as a result of reduced friction, there is a higher resistance to wear. As a result of an appropriate design of the gear train, a speed reduction can be achieved. Consequently, a low drive force or a low drive torque on the drive device is sufficient to achieve the necessary actuation force. An electric motor may be used as the electrical drive device. As a result of the elimination of control surfaces on the sliding spool for the actuation of the actuator element, the construction of the sliding spool can be made simpler, more compact and more economical to manufacture.
In one embodiment of the invention, the output element is effectively connected with a cam disc to actuate the actuator element. With a cam disc, while the output element is rotating, the actuator element can be deflected with a low actuation force, and the pilot control valve can thus be moved into the open position.
The cam disc may be connected with a rocker arm which is effectively connected with the actuator element. When the output element is in rotation, the rocker arm is thus rotated and deflects the actuator element. It is thereby possible to reduce the opening stroke of the pilot control valve that results from the movement of the actuator element to the angle of rotation of the output element. This increases the precision of the resolution. In addition, with an actuation of the actuator of this type by a rocker arm, an actuation of the actuator pin that does not involve any transverse forces becomes possible. As a result, a low actuation force is necessary for the actuation of the pilot control valve.
A further reduction of the actuation force for the pilot control valve can be achieved if the rocker arm is provided with a roller that is arranged to rotate and is in contact against the cam disc. The connection between the cam disc and the rocker arm is therefore almost frictionless.
In one configuration, in which the actuator element is an actuator pin, there are advantages if the actuator pin is a sphere on the end opposite the pilot control valve, and is mounted in a conical-shaped recess of the rocker arm. It is thereby possible to deflect the actuator pin easily and without any transverse forces, whereby wear on the actuator pin caused by transverse forces is also eliminated.
The cam disc can thereby be non-rotationally connected with the output element. In order to keep the number of components low, the cam disc may be integrally connected with the output element. To actuate the sliding spool and to actuate the pilot control valve, all that is necessary is an output element which is in a driving connection with the sliding spool and is connected with the actuator element via the rocker arm.
In one embodiment of the invention, the output element is effectively connected with the sliding spool by a connecting rod. The output element, together with the connecting rod and the sliding spool, forms a crank mechanism. With a connecting rod, it is easily possible to convert a rotational movement of the output element into a linear movement of the sliding spool. A connecting rod of this type requires only small angular deviations from the longitudinal axis of the sliding spool to achieve the piston stroke of the longitudinal shutter. Only low transverse forces occur on the sliding spool, and thus a low actuation force is necessary for the deflection of the sliding spool.
In one refinement of the invention, the connecting rod is suspended in the sliding spool and/or in the output element. The installation of the connecting rod can thereby be performed simply by suspending the connecting rod in the sliding spool and/or the output element. Removing it is also simple. No additional fastening parts are required to connect the connecting rod with the output element and the sliding spool, which results in reduced manufacturing costs and easier assembly.
In one embodiment of the invention, to connect the connecting rod with the sliding spool and/or the output element, there is a sphere which can be fastened in a spherical-shaped
Linde Aktiengesellschaft
Michalsky Gerald A.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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