US3419030A - Fast evacuation valve - Google Patents

Description

J. L. GRATZMULLER 3,419,030

FAST EVACUATION VALVE Filed Nov. 8, 1965 shet of s Dec. 31, 1968 J. GRATZMULLER 3,419,030

FAST EVACUATION VALVE Filed Nov. 8, 1965 Sheet 2 of 3 J. L. GRATZMULLER FAST EVACUATION VALVE Filed Nov. 8, 1965 Sheet al f 1 as 7 2 A w A00 45 2 25' 76 I W ?i Unite States Claims. 61. 137-102 ABSTRACT OF THE DISCLOSURE A fast evacuation valve for a hydraulic control jack wherein a chamber interposed in the jack feed conduit is sub-divided by a piston into first and second compartments connected to the pressure fluid inlet conduit and jack. An evacuation conduit communicates with the second compartment and an evacuation valve connected to the piston controls its orifice. The piston has passage means permitting communication between the compartments controlled by a non-return valve allowing fluid flow only from the supply to the jack. This latter valve is a ring concentric with the piston slidable on the exterior of a portion between the piston head and evacuation valve.

This invention relates to improvements to fast evacuation valves for hydraulic jacks and, inter alia, hydraulic jacks for the control of circuit breakers.

A valve according to the invention, which will hereinafter be referred to as a fast evacuation device, is an automatic three-way valve adapted to provide selectively communication between a jack, or more generally any hydraulic load, and a pressure fluid source, or between such jack and a large-section evacuation pipe, with this second arrangement occurring automatically as soon as the pressure in the jack is greater than that in the feed pipe connecting the source to the jack.

A valve of this type therefore enables the jack evacuation to be controlled simply by decompression of the feed pipe (for example in the case of a single-acting jack adapted to make a circuit breaker against the action of elastic means adapted to break the circuit breaker) or alternatively when the pressure in the jack is higher than in the feed pipe (for example in the case of a doubleacting jack which provides for make and break of the circuit breaker upon its direction of operation).

In either case a valve of this type enables the liquid to be evacuated without passing it through the feed pipe, which is generally very long and of relatively small section, since this would have the disadvantage of braking evacuation, and the evacuated liquid flows through a pipe reserved solely for this purpose and which can therefore be both short and large. In circuit breaker control systems, in which operations have to be very fast, particularly on break, it is very advantageous for the valve or valves to be disposed in the immediate vicinity of the jack that they control.

A valve of this type has already been described in my US. Patent No. 2,888,909.

The present invention relates to certain improvements giving a simpler and hence cheaper construction than those of prior art valves, and inter alia because of the elimination of any internal precision machining or any male or female screwthreading of the movable closure elements of the valve. Also, these new features give a freer choice for the sections of the various passages whereby the hydraulic fluid flows through the valve. Finally, a new type of construction enables a single valve body to be fitted to different hydraulic circuits as a result of the specific shape of the valve body and the fact that 3,419,030. Patented Dec. 31, 1968 it is adapted to receive various types of connecting members for the hydraulic circuit.

According to the invention, a fast evacuation valve for a hydraulic jack comprises a chamber interposed in the jack feed conduit and subdivided, by a piston sliding in a bore in the valve body, into a first compartment connected to the pressure fluid inlet conduit and a second compartment connected to the jack; a large-section evacuation conduit communicating with the second compartment and with its orifice controlled by an instantaneously opening evacuation valve which is connected to the piston; and at least one passage formed in the piston so that the two compartments can communicate with one another, with the passage being controlled by a non-return valve which allows fiuid to flow only from the supply to the jack and which is in the form of a ring concentric with the piston and slidable on the outside of an intermediate cylindrical portion between the head of the piston and the evacuation valve.

According to one embodiment, the evacuation valve is formed by the free end of the piston rod, with the rod preferably being an integral part of the piston, as is therefore the evacuation valve; the ring which forms the non-return valve slides around the said piston rod.

In a preferred embodiment, the passage or passages formed in the piston for communication between the two compartments lead radially into the second compartment on the outer surface of the piston rod and the sliding ring controlling the opening of the passages has surfaces normal to the sliding axis, with such surfaces being subject to the pressure difference between the first and second compartments, the resultant forces controlling the opening and closure of the valve.

Advantageously, at least one of the valves, the evacuation valve or the non-return valve, is permanently loaded into the closure position by a spring.

According to one feature, the valve body is of parallelepipedic external shape, preferably of square section, and connection members are secured in sealing-tight relationship to one or more of the flat surfaces of the valve body to which the valve conduits lead, with such members enabling the valve to be connected to the various conduits of the hydraulic circuit for control.

By this arrangement the connections may be made according to the most favorable orientation with a standard valve body and a small number of different connection members.

The invention will be more readily understood from the following detailed description and the accompanying drawings which illustrate various embodiments of the invention by way of non-limitative example.

FIGURE 1 is an axial section of one embodiment of a fast evacuation device according to the invention.

FIGURE 2 is a view partly in elevation and partly in section showing an example of the use of such a fast evacuation device in a hydraulic control circuit for a circuit breaker.

FIGURE 3 is an axial section of another embodiment of the invention.

FIGURE 4 is a perspective view showing the arrangement of hydraulic connections according to a variant of the invention.

FIGURE 5 is a view partly in elevation and partly in section of a fast evacuation device according to the invention in combination with a hydraulic jack.

FIGURES 6 and 7 are views partly in elevation and partly in section of two variants of hydraulic control jacks for a circuit breaker, with which a fast evacuation device according to the invention may be combined.

Referring to FIGS. 1 and 2, a fast evacuation device valve body "2 is formed with a bore 4 which provides a chamber between a pressure oil inlet pipe 6 and a feed pipe 8 to a hydraulic jack 10. The chamber is subdivided 'by a piston 12, which slides in the bore 4, into a first compartment 14 connected to the pressure fluid inlet pipe and a second compartment 16 connected to the jack 10. An evacuation pipe 18 communicates with the compartment 16 and its orifice or seat 20 is controlled by an evacuation valve 22 of the instantaneous opening type, which is connected to the piston 12 and which in the example illustrated forms an integral part thereof. A plurality of passages 24 are formed in the head of piston 12 so that the two compartments 14 and 16 can communicate and these passages are controlled by a nonreturn valve which allows oil to flow only from compartment 14 to compartment 16. According to the invention, the non-return valve is in the form of a ring 26 which is concentric with the piston and which slides on the outside of an intermediate cylindrical portion, or piston rod 28, between the piston 12 and the valve 22.

According toa preferred embodiment, the two valves 22 and 26 are respectively urged into the closure position by springs 30 and 32 respectively. Of course, in the case illustrated in FIG. 1, in which the spring 32 bears against the end of the bore 4, the spring 30 is stronger than the spring 32.

The operation of the fast evacuation device will be described just briefly in connection with FIG. 2 which diagrammatically illustrates a hydraulic control system for a circuit breaker as described in my US. Patent No. 2,900,469. In this control system, when the jack receives pressure oil from an oleopneumatic accumulator 36 piston 34 of the jack brings movable contact 38 of the circuit breaker into the make position against fixed contact 40 and holds it in this position against the action of break spring 42. The fast evacuation device 2 has been shown as being directly secured to the jack 10.

When control valve 44 is brought into position 44', pressure oil from the accumulator acts on the top surface of the piston 12 and firmly applies the valve 22 to its seat to shut off the evacuation. Under the pressure effect the ring type valve 26 moves away from the apertures 24 against the spring 32 and oil flows into the chamber 16 and then via pipe '8 to the jack 10 in which it pushes the piston 34 back against the spring 42. The circuit breaker is thus in the make position. When the valve 44 is returned to the position shown in FIG. 2, feed pipe 46 expands and the higher pressure in the jack 10 applies the ring type valve 26 firmly against the passages 24 at the same time as the piston 12 is lifted against its spring 30. The evacuation valve 22 therefore opens instantaneously and the oil contained in the jack 10 is rapidly evacuated via the large pipe 18 to a tank 48. The circuit breaker can therefore break at high speed under the effect of its spring 42 without there being any braking as a result of the oil.

Of course, a fast evacuation device of this kind can be used in numerous hydraulic control circuits different from the one diagrammatically illustrated and, inter alia, control circuits of the type described in my US. Patent No. 2,900,960.

The new fast evacuation device according to the invention has numerous advantages over evacuation valves known heretofore, such advantages being due, more particularly, to the external arrangement of the non-return valve. None of the moving .parts of the valve has either a male or female screwthread and no precision female bore is required, so that the cost price is greatly reduced. In the embodiment shown in FIG. 1, the only precision machining requirement is concentricity between the bore 4 (which guides the piston 12) and the evacuation orifice 20 (which acts as the valve seat) to give good closure of the frustoconical evacuation valve 22. However, it will be apparent from the embodiment shown in FIG. 3 that even this precise machining: can be avoided. Also, the arrangement of the non return valve outside the piston, or more particularly outside the piston rod, enables the passages 24 to be given a total section much larger than in prior art evacuation valves in which, for a given evacuation aperture section, the section offered to the passage of the oil to feed the jack is sometimes inadequate.

The preferred embodiment shown in FIG. 3 comprises all the main elements already described in connection with FIG. 1 (with the same reference numerals). One of the variants comprises arranging the passage orifices 24' which form the communication between the compartments 14 and 16 to lead radially to the outer surface of the piston rod 28 instead of in parallel relationship to the axis as in FIG. 1. To ensure that the pressures exerted by the pressure oil on the ringtype non-return valve 26 produce an axial force thereon, the ring is formed with an inner shoulder 48' and is continued in the form of a skirt 50 which gives substantially sealing-tight sliding of the ring on the rod 28.

The ring type valve return spring 32 can bear against a collar 52 which is held by a resilient gasket 54 fitted in a groove in the rod 28. The two springs 30 and 32 are thus independent.

These variants give a larger total passage section through the orifices 24', Which can be of larger diameter than in the case shown in FIG. 1, and also do away with the need for the oil to have to flow through the coils of the springs 30 or 32 (as in FIG. 1), thus eliminating any adverse pressure losses or vibrations.

Another variant is the evacuation valve 22, which is flat, i.e. the co-operating surfaces of the seat 20 and of the evacuation valve are perpendicular to the valve axis. These flat surfaces can be machined economically and yet with precision, and the sealing properties of the evacuation valve no longer depend on perfect concentricity of the bore 4 and the evacuation valve seat, so that the valve production is facilitated.

According to another variant, the evacuation pipe 18' for the valve, which is connected to the axial conduit 18, discharges radially on the valve side, while the jack feed conduit or conduits 8 are formed in parallel relationship to the axis of the valve and lead into the compartment 16 whose diameter is larger than that of the bore 4. This arrangement enables the fast evacuation device to be fitted directly at the end of the jack 10 which it is required to control, for example by means of a collar 56 held on the evacuation device body by a resilient gasket 58 and secured to the jack by screws 60. A gasket 62 provides sealing-tightness between the fast evacuation device and the jack 10.

In circuit breaker hydraulic control installations it is frequently advantageous, as described in my US. Patent No. 2,933,069, to regularize the rates of liquid flow corresponding to the make and break operations by throttle means interposed in the pipes or conduits, inter alia with thin-walled calibrated jets disposed as close as possible to the jacks whose speed is to be controlled.

A calibrated jet may advantageously be combined with a fast evacuation device according to this invention. A jet 64 can rest on a step 66 on the piston 12 and be held thereon by the piston return spring 30. This arrangement gives a very simple and economic system, enables the jet to be disposed immediately near the jack, thus minimizing any vibrations due to the compressibility of the liquid, and gives a pressure loss which tends to apply the valve 22' to its seat.

According to a preferred embodiment, the fast evacuation device body 2 is given a parallelepipedic external shape of square section (FIG. 4) and connection members 64-66 are fitted to its ends opposite the feed and drain conduits. With just two types of connection members, one with an axial outlet 68 and the other with a side outlet 70, it is possible to obtain any required direction of the outlet conduits. The connection members are simply secured to the valve body by four screws 72 arranged in the form of a square and four 90 directions can be chosen for each connection member. Of course, a gasket 74 is provided between the valve body and the connection members (FIG. 5).

The valve conduit 8 or 8' can be connected to the jack via a connection member 74, the same as those mentioned hereinbefore, which is secured by means of four screws to the fiat side of the valve body (FIG. 4) and can be directed as required.

Preferably, however, the evacuation device is generally fitted directly to the jack as shown in FIGS. 3 and 5. In the latter figure, the parallelepipedic body 2 of the fast evacuation device is secured by four screws 76 to a base 80 into which cylinder 82 of the jack is screwed. A gasket 62 is provided between the evacuation device body and the base.

Jack piston 84 shown in this figure has a gasket 86 formed by a plurality of rings which are kept compressed by a spring. A gasket of this kind has been described, inter alia, in my US. Patent No. 2,847,262 and US. continuation-in-part application No. 378,901.

In the jack shown in FIG. 5, in combination with a fast evacuation device, the piston rod is guided at the top end of the cylinder 82 by a metal ring 88 provided with a ring gasket 90 which prevents any penetration of moisture and dust into the space between the calibrated piston rod and the cylinder 82. This ring gasket also cleans the piston rod on each operation. However, said space, whose volume varies during the make or break operations (in the case in which the jack actuates the moving contact of a circuit breaker), must not be completely sealed and must be able to evacuate any oil leakages.

To this end, the wall of the cylinder 82 is formed with a respiration aperture 92 which is normally closed by a valve 94 loaded by a spring 96 so as to prevent any penetration of moisture, with the valve opening only in the event of an excess pressure in the said space.

FIGS. 6 and 7 show another two examples of a fast evacuation device according to the invention combined with hydraulic control jacks for a circuit breaker.

The jacks shown are direct long-stroke jacks of the type described in my French Patent No. 1,391,147.

These two figures show fast evacuation devices 2 with a body of parallelepipedic shape directly secured by screws 76 to the jack base 80.

In this variant, oil inlet and evacuation connections 98 and 100 are directly screwed into the valve body (as in FIG. 1) without the use of orientable connection members of the kind described in connection with FIGS. 4 and 5.

This invention is not to be confined to any strict conformity to the showings in the drawings but changes or modifications may be made therein so long as such changes or modifications mark no material departure from the spirit and scope of the appended claims.

I claim:

1. A fast evacuation valve for a hydraulic jack, and more particularly for a hydraulic control jack for a circuit breaker, comprising a valve body, a jack feed conduit, a pressure fluid inlet conduit, a chamber interposed in the jack feed conduit, a piston having an integral piston rod slidable in a bore in the valve body sub-dividing the chamber into a first compartment permanently connected to the pressure fluid inlet conduit and a second compartment connected to the jack, a large-section evacuation conduit communicating with the second compartment and having an orifice, an instantaneously opening evacuation valve formed by the end of the piston rod controlling said orifice, first spring means urging said evacuation valve to closed position, at least one passage formed in the piston to provide communication between the two compartments, a non-return valve controlling said passage and allowing fluid to flow only from the supply to the jack, second spring means urging the non-return valve to closed position, said first spring means being stronger than the second spring means, and said non-return valve being defined by a ring concentric with the piston and slidable on said piston rod.

2. The valve according to claim 1 wherein the evacuation valve and said orifice have flat cooperating surfaces perpendicular to the axis of movement of the valve.

3. The valve according to claim 1 wherein the piston is provided with a bore opening into said first compartment, said piston rod having radial apertures interconnecting the bore in the piston rod and the second compartment, and the slidable ring controlling the radial apertures comprises at least one shoulder on its inner surface so that the resultant of the pressure forces acting on the ring extends in parallel relationship to its axis and not radially.

4. The valve according to claim 1, comprising a calibrated jet to regularize the rate of flow of the hydraulic fluid, said jet being provided in the communication passage of the valve.

5. A fast evacuation valve for a hydraulic jack, and more particularly for a hydraulic control jack for a circuit breaker, comprising a valve body, a jack feed conduit, a pressure fluid inlet conduit, a chamber interposed in the jack feed conduit, a piston slidable in a bore in the valve body sub-dividing the chamber into a first compartment connected to the pressure fluid inlet conduit and a second compartment connected to the jack, a large-section evacuation conduit communicating with the second compartment and having an orifice, an instantaneously opening evacuation valve connected to the piston controlling said orifice, at least one passage formed in the piston to provide communication between the two compartments, a non-return valve controlling said passage and allowing fluid to flow only from the supply to the jack and said non-return valve being defined by a ring concentric with the piston and slidable on the outside of an intermediate cylindrical portion between the head of the piston and the evacuation valve, a calibrated jet to regularize the rate of flow of the hydraulic fluid, said jet being provided in the communication passage of the valve and said jet being in the form of a washer having a calibrated orifice and held against the piston in register with said passage by a spring which permanently loads the piston in the position corresponding to closure of the evacuation valve.

References Cited UNITED STATES PATENTS 122,544 1/1872 Westinghouse 137-102 2,488,949 11/ 1945 Walsh 137-102 XR 2,706,487 4/1955 Wilson 137-102 2,888,909 6/ 1959 Gratzmuller 121-38 2,900,960 8/1959 Gratzmuller 121-38 2,933,069 4/ 1960 Gratzmuller 121-38 3,042,061 7/ 1962 Dobrikin 137-102 WILLIAM F. ODEA, Primary Examiner.

WILLIAM H. WRIGHT, Assistant Examiner.

US. Cl. X.R.

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