Quick-acting valve

Details Quick-acting valve Quick-acting valve

2000-02-14

2001-08-28

Shaver, Kevin (Department: 3754)

Valves and valve actuation

Electrically actuated valve

Having element dimensionally responsive to field

C251S129140, C251S349000

Reexamination Certificate

active

06279872

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a quick-acting valve having a chamber which comprises an inlet opening, an outlet opening and a valve seat which can be closed with a movable valve body.
For certain applications quick-acting valves are required which are capable of permitting a fluid flow to pass abruptly through them as well as allowing a high switching rate. Applications for such valves are for example spectrometers where gas samples of precisely measured volumes are subjected to a spectrographic examination, the energizing of the control nozzles of satellites and the field of microsystem technology. For such applications valves with extremely short switching times and high repetition rate are required.
DE 38 35 788 A1 describes a quick-acting ball valve comprising a ball seated in a valve seat. An actuator device acting transversely to the valve seat allows the ball to be removed from the valve seat by a lateral impact. The resultant flow pushes the ball back to the valve seat. This quick-acting valve has turned out to be successful in practical application.
In the journal O+P “Ölhydraulik und Pneumatik” 38 (1994), no. 9, pages 554-562, employment of piezoelectric actuators for quick-acting actuating drives are described. Piezoelectric actuators are used for example in dosing units for fluids with the actuator being attached to a nozzle tube which injects the fluid into an air jet. In this way quick-acting dosing devices suitable for various viscosities and droplet rates can be realized.
In the journal VDI-Z 119 (1977), no. 11-June (1), pages 569-570 a valve for fuel injection is described where a piezoelectric rod expands and contracts to control the valve opening process according to the pulse duration/modulation principle.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a quick-acting valve which is improved with regard to short switching times, high repetition rate and numbers of cycles limiting the service life.
According to the invention this object is solved in accordance with the features stated in claim
1
.
In the valve of the invention the valve seat is connected with an actuator which, when being operated, moves the valve seat and removes it from the valve body at such a high acceleration rate that the valve body is not capable of following and is lifted off the valve seat. The passage of the valve seat is opened for a short defined period until the valve body returns to the valve seat under the force exerted by the flowing medium and closes it. Then the actuator sets the valves seat which is closed by the valve body back to its initial position so that the next cycle can be carried out.
The quick-acting valve of the invention may be configured in such a way that short switching times in the order of max. 100 &mgr;s are realized. In the practice repetition rates of 400 to 1000 Hz have been attained. The response rate and the repetition rate depend, of course, on the overall size of the valve and in particular on the mass of the valve body. The valve body should have a low density which results in a small mass. The valve body may for example be executed as a hollow body.
The valve of the invention is in particular provided for controlling gases. It may however also be used for controlling fluids. For example, the valve is suited for fuel injection in internal combustion engines.
The actuator supporting the valve body is preferably executed as piezoelectric contraction body which contracts in response to an actuating signal. Alternatively, the actuator may for example also operated as an electromagnetic unit. It is essential that a high acceleration of the valve seat is achieved for a short period, which is higher than the acceleration of the valve body subjected to the medium pressure.
A particular advantage of the valve according to the invention is the low wear rate of valve body and valve seat. Since the valve seat moves away from the valve body in axial direction and subsequently takes up the valve body also moving ing axial direction, the impact forces are distributed annularly onto the valve seat and the valve body. For further wear reduction the actuator is controlled in such a way according to the invention that, in response to an actuating signal, it moves the valve seat quickly and then more and more slowly in order to smoothly catch the ball lifted off the valve seat.
A ball may be used as valve body. However, the invention is not limited to this configuration, it is rather also possible to use a conical or similarly shaped valve body.
In the following embodiments of the invention are explained in detail with reference to the drawings in which:


REFERENCES:
patent: 3819116 (1974-06-01), Goodinge et al.
patent: 3949938 (1976-04-01), Goodinge
patent: 4176822 (1979-12-01), Chadwick
patent: 4762300 (1988-08-01), Inagaki et al.
patent: 4907748 (1990-03-01), Gardner et al.
patent: 4971106 (1990-11-01), Tsutsui et al.
patent: 5076314 (1991-12-01), Ikehata et al.
patent: 5125625 (1992-06-01), Gooch, IV et al.
patent: 3835788 (1988-10-01), None
patent: 1-105080 (1989-04-01), None
patent: 63-1999978 (1998-08-01), None
patent: 846800 (1981-07-01), None
Journal O+P Olhydraulik und Pneumatik 38 (1994), No. 9, pp. 554-562.
Journal VDI-Z 119 (1977), No. 11-Jun. (1), pp. 569-570.

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