US3478765A - Pilot valve - Google Patents

Description

Nov. 18, 1969 I B. Kl 3,478,765

7 PILOT VALVE Filed April 18, 1967 INVENTOR DA W0 8. KIRK A 7' TORNE' Y United States Patent US. Cl. 137-815 9 Claims ABSTRACT OF THE DISCLOSURE A liquid flow sensitive pilot valve having no moving parts exposed to the liquid and in which One wall or a plurality of walls in sequence are provided for liquid lock-on dependent on the flow, the walls having control signal ports affected by the flow along the wall in which the port is located.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to liquid flow sensitive pilot valve in which a jet of fluid from a nozzle has its path determined by the rate of flow.

Description of the prior art Various types of pilot valves have heretofore been proposed most of which have had moving parts with accompanying problems of maintenance, necessity for adjustment, and limited useful life.

It has also been proposed to employ transmitted and received fluid jets with the pick up influence or modified by an external object. These were not however, dependent on variations of the rate of flow of the fluid.

SUMMARY It is the principal object of the present invention to provide a liquid flow sensitive pilot valve having no moving parts in which a jet of liquid delivered into a chamber takes a path determined by the rate of flow of the liquid of the jet, and in which in one condition of flow the liquid passes to one path and for a different rate of flow of the liquid, the liquid locks onto a surface which has a central signal port.

It is a further object of the present invention to provide a pilot valve of the character aforesaid in which the valve can be embodied in a multiple stage unit.

It is a further object of the present invention to provide a pilot valve of the character aforesaid which is simple in construction and may be cast or molded.

It is a further object of the present invention to provide a pilot valve responsive to rate of flow therethrough, and in which the liquid from a nozzle while subject to gravity may be locked onto an interior surface which has a control signal port.

BRIEF DESCRIPTION OF THE DRAWING The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part thereof, in which:

FIGURE 1 is a top plan view of a preferred embodiment of a pilot valve in accordance with the invention;

FIG. 2 is a longitudinal central sectional view, enlarged, taken approximately on the line 2-2 of FIG. 1;

FIG. 3 is a sectional view, taken approximately on the line 33 of FIG. 2;

FIG. 4 is a sectional view, taken approximately on the line 44 of FIG. 2;

FIG. 5 is a setcional view, taken approximately on the line 55 of FIG. 2; and

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FIG. 6 is a diagrammatic view showing one mode of use of a simplified form of pilot valve in accordance with the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings, the pilot valve in accordance with the invention preferably includes a housing 10, which may be made in any desired manner such as by molding or casting, of metal, synthetic plastic or any desired material. The material is preferably resistant to and free from corrosion by the liquid being handled.

The housing 10 has a liquid inlet connection 11 which is preferably provided with an interior transitional section 12. The section 12 has an interior shape which advances from circular at the inlet to rectangular at its outlet. A conventional tubular conduit 14 can be connected to the inlet connection 11 for the introduction of the liquid whose flow variation is effective within the pilot valve. Immediately beyond the transitional section 12, a nozzle section 15 is provided, preferably rectangular in transverse cross section. The longitudinal axis of the nozzle section 15 in the particular embodiment is at an angle of 60 with respect to the vertical. The nozzle section 15 preferably has an upper sharp terminal edge 16 and a lower sharp terminal edge 17 on an interior face 18.

The housing 10 includes a chamber 20 with which the nozzle section 15 is in communication. The chamber 20 has opposite vertical side walls 21, a vertical end wall 22 connecting the side walls 21, an inclined bottom wall 23 extending downwardly from the face 18 and connecting the side Walls 22, and a liquid discharge connection 24 at the lower terminus of the bottom wall 23.

A fluid connection 25 is provided for delivery of the fluid from the discharge connection 24.

The chamber 20 is bounded at the top thereof by a wall portions which provides an upwardly inclined channel 26.

The channel 26, extending from the face 18 and accord- I ingly in upwardly offset relation to the upper edge 16 of the nozzle section 15, has an inclined surface 27 Which can be flat and which provides a surface for liquid lock-on. The surface 27 has a sharp edge terminal 28 and upstream of the edge 28 a port 29 is provided to which a signal take off connection 30* is connected.

In set back relation to the inclined surface 27, a second surface 32 is provided for liquid lock on. The surface 32 inclined as at 33 and substantially parallel to the longitudinal axis of the nozzle section 15 has its terminal portion 34 curved and brought substantially horizontal.

The surface 32, a sufficient distance therealong beyond the edge 28 for liquid lock on to occur has a port 35 to which a signal take-off connection 36 is connected.

The chamber 20 including the upper end of the channel 26 are in communication with a vent opening 38, for venting, and to which a fluid connection 39 is connected which extends to any desired pressure reference.

Referring now to FIG. 6, a simplified form of pilot valve 10a is illustrated, connected to a diverting valve 40. The diverting valve 40 has a supply connection 41 for fluid connected thereto for delivery through a nozzle 42 into a fluid interaction chamber 43. The chamber 43 is non-symmetrical and has a favored lower wall 44 which is blended into the axis of the nozzle 42 with only a small set back at the exit end of the nozzle 42. The upper Wall 45 has a larger set back from the nozzle 42 and diverges from the nozzle 42. The walls 44 and 45 respectively control the delivery into the discharge passageways 46 and 47.

The supply connection 41 has a fluid connection 48 extending therefrom through a restriction 49 to the inlet connection 11 of the pilot a. The take off opening 29 is connected to the nozzle 42 close to its exit end.

The mode of operation will now be pointed out.

Assume that liquid is supplied through the inlet connection 11, the transitional section 12 and the nozzle section 15 into the channel 26 of the chamber 20.

At a very low rate of flow the liquid, as a jet from the nozzle section 15 will not reach the surface 27 or if it does reach the surface does not contact that surface sufficiently to lock on. The fluid path of the jet is irifiuenced by the accelerating field such as that of gravity acting on the jet in a direction away from the surface 27. The set back on the surface 27 at the interior face 18 aids in preventing undesired lock on. The liquid from the nozzle section 15 will accordingly fall toward bottom wall 23, move downwardly therealong, and then out through the discharge connection 24. The ports 29 and 35 are subect to the pressure prevailing in the chamber 20 since nothing has brought about any change at those ports.

At a higher level of liquid flow through the nozzle section 15, and subject as before to the accelerating field, the jet will contact the surface 27 and lock onto that surface by the Coanda effect. At the edge terminal 28 the liquid will commence to fall in the chamber 20 for discharge through the discharge connection 24.

The continuous flow of liquid along the surface 27 will revent air from being exhausted through the port 29 and pipe 30 thereby providing change of condition which is useful for signaling purposes available in the take off connection 30.

At a still higher rate of liquid flow through the nozzle section 15, and subject as before to the accelerating field, the jet will contact the surface 32 and lock onto that surface by the Coanda effect and then turn downwardly in the chamber 20, and discharge through the liquid discharge connection 24.

The continuous flow of liquid along the surface 32 will prevent air from being exhaust through the port 35 and pipe 36 thereby providing a change of condition which is useful for signaling purposes.

Upon decrease of flow through the nozzle section 15 the reverse of the operations just described would occur.

The terminal edge 17 and the set back of the Wall 23 with respect to the nozzle is such as to prevent any lockt on of liquid on the wall 23 which would prevent its movement in the channel 26.

The pilot valve described above is particularly suitable for use with the diverting valve described and claimed in the application of C. B. Moore and Robert B. Adams, filed Mar. 27, 1967, Ser. No. 626,027, but is not limited to such use.

Referring now to FIG. 6, when the take off opening 29 is open to the atmosphere, air coming through the opening 29 will detach the main stream delivered by the nozzle 42 from the lower wall 44. When, however, only liquid can be drawn up through the take-off opening 29, this will not be sufficient to supply to entrainment of the main jet from the nozzle 42. The pressure below the main jet will fall and since the biasing tends to favor flow along the lower wall 44 the jet will follow the lower wall 44, under these conditions.

The pilot valve of the present invention has a wide variety of uses where a signal is desired dependent upon rate of flow of a liquid and particularly where it is pre ferred not to have any moving parts exposed to the liquid.

I claim:

1. A liquid flow responsive device comprising:

a source of liquid,

a nozzle to which said source i connected,

a surface in converging relation to the axis of the nozzle and in such converging relation extending downstream of the nozzle to a location spaced from said axis less than one half the width of the nozzle,

said surface further being arranged generally transverse to the direction of force of an accelerating field whereby the liquid from said nozzle will lock-on to said surface at a flow rate in excess of that necessary to overcome the effect of said accelerating field tending to urge flow therefrom,

said surface having a signal take off opening positioned such that the opening will be in the path of fluid flow when lock-on occurs.

2. A liquid flow responsive device as defined in claim 1 in which:

a housing is provided with an interior chamber into which said nozzle is directed,

said surface is along an upper wall of said housing,

and

said chamber is bounded by facing side walls.

3. A liquid flow responsive device as defined in claim 2 in which:

said nozzle is of predetermined width, and

said side walls are spaced the same width as that of the nozzle.

'4. A liquid flow responsive device as defined in claim 2 in which said chamber is vented to a gaseous atmosphere, and

said take off opening is subject to said atmosphere at low liquid velocities and is sealed from said atmosphere at higher liquid velocities.

5. A liquid flow responsive device as defined in claim 4 in which:

said nozzle is rectangular in cross section, and

the upstream end of said surface is joined to the nozzle in fluid tight relation.

6. A liquid flow responsive device as defined in claim 5 in which:

said surface beyond said take off opening has a set back portion with a surface portion therebeyond inclined in a direction toward the flow axis of the nozzle, and

said surface portion has a second signal take off opening therein.

7. A liquid flow responsive device as defined in claim 4 in which:

a liquid diverting valve is provided having a control port, and

said signal take off opening is connected to said control port.

8. A liquid flow responsive device as defined in claim 2 in which:

a liquid diverting valve is provided having a control port, and

said signal take off opening is connected to said control port.

9. A liquid flow responsive device as defined in claim 1 in which:

a liquid diverting valve is provided having a control port, and

said signal take off opening is connected to said control port.

References Cited UNITED STATES PATENTS 3,283,768 11/1966 Manion 137-81.5 3,313,313 4/1967 Katz l3781.5 3,379,203 4/1968 Manion l3781.5

M. CARY NELSON, Primary Examiner W. R. CLINE, Assistant Examiner

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