US2688314A - Arrangement of control valves - Google Patents

Description

p 7, 1954 H. F. HOLM ETAL 2,688,314

ARRANGEMENT OF CONTROL VALVES Filed May 1, 1953 INVEN HFHOLM Al F, HOPPE Patented Sept. 7, 1954 ARRANGEMENT OF CONTROL VALVES Hans Feser Holm and Nils Ferdinand Hoppe,

Stockholm, Sweden, assignors to Smallpeice Limited, Parkshot, Richmond, Surrey, England Application May 1, 1953, Serial No. 352,536

3 Claims.

This invention relates to an arrangement for the control of a double-acting, pressure-responsive device by two coacting control valves (A and B), each of the type in which a valve member is slidable in a coacting cylinder by a fluid pressure applied alternately to cylinder chambers at the ends of the valve member, whereby the device is selectively supplied with the fluid pressure by one of the control valves (A). Our copcnding patent application Serial No. 352,537 also relates to a valve of this kind.

In the past recourse has been had to separate press-knob or other impulse valves. The main object of the present invention is to operate an arrangement as aforesaid by means of a single impulse valve.

According to the invention a single impulse valve on operation connects the fluid pressure to the cylinder of the other control valve (3) so that, dependently upon the position of the slidable valve member of the valve B, the fluid pressure will pass through one of two outlets from the valve B which respectively lead to the cylinder chambers at the ends of the valve A, whereby to actuate the valve A in one direction and to cause the valve A to supply the pressure-responsive device accordingly through one of its two outlets, both the outlets from the valve A also being connected with the cylindrical chambers at the respective ends of the valve B so that fluid pressure flowing through the valve A will move endwisethe slidable member of the valve B when the actuating member of the impulse valve is released, provided that the impulse valve has remained operated for a predetermined period.

In the case where the control valves are operated entirely manually, there is the advantage that there is only one press-knob to operate instead of two as previously, and this is of great significance for rendering fully automatic a machine, with diiferent working operations, wherein movable machine parts are arranged to carry out the required control work. Thus, with the arrangement according to the invention a single reciprocating part, for example, of the machine could be used automatically to control a control valve by actuating the single impulse member.

One form of arrangement, according tothe invention and for controlling the operation of a 2 double-acting piston and cylinder arrangement, is diagrammatically illustrated in the accompanying drawing.

Referring to the drawing, one of the control valves, which is of known construction and indicated generally by the letter A, comprises a body I containing a valve member 2 with four pistons 3 to 6. A supply conduit 1- for the pressure medium (usually air) leads into the body between the inner pistons and 5, and outlets 8 and 9 from the body are respectively arranged between each outer piston and the adjacent inner piston (i. e., from between pistons 3 and 4 at the left of the figure and from between pistons hand 6 at the-right). Conduits l0 and H leading to opposite ends of a double-acting working cylinder [2, of which the coacting piston is shown at l3; are connected to the body I so that, in dependence on the position of the valve member 2, one communicates with the supply conduit 1 whilst the other communicates with one of the outlets 8 or 9.

Two cylinders I 4 and I5, in the ends of the body I and for coaction with the pistons 3 and 6, are connected by conduits I6 and I7 to the casing I8 of a second valve which is designated generally by the letter B and which forms an essential part of the invention.

The valve casing 18 has a central cylindrical bore [9 with, at its ends, smaller-diameter coaxial bores 20 and 2 l. A valve member 22, working in the bores, has at its centre a piston 23'for coaction with the central bore [9, and, at its ends, pistons 24 and 25 for coaction with the bores'ZlJ and 2| respectively. Each of the pistons 24 and 25 has two annular grooves containing packing rings for sealing contact with the co.- acting bore.

The conduits I6 and I! communicate, through radial ducts in the casing l8, with opposite ends of the central bore l9, and another radial duct in the casing I8 is connected to a conduit 26 which leads to an impulse valve 28 controllable by a spring-biassed press-knob 27. The impulse valve 28 in the example shown is a three-way valve which normally keeps the conduit 26 in communication with the outer air through an outlet 29, but which, on pressing the knob 2! against its bias, connects the conduit 26 instead to a-conduit 39 leading from a pressure; medium source (not shown) The conduits i and II between control valve A and the working cylinder l2 communicate, through branch conduits 3| and 32, respectively, with the outer ends of the bores 20 and 2| of valve B, and the bores 20 and 2|, near their inner ends, communicate with the outer air through ducts 33 and 34 passing radially through the casing [8.

Assuming that the movable parts are in the position shown and that air pressure is used, by pressing the press-knob 21 the air pressure is supplied through the conduit 26 into the bore l9 at the right of the piston 23. From here the air is fed through the conduit If to the cylinder at the right of control valve A and this causes the valve member 2 to move to the left so that the air pressure conduit 1 is put into communication with the conduit H leading to the left end of the working cylinder i2. At the same time a communication is opened between the conduit ll, leading from the right end of the working cylinder, and the outlet 9, and the piston i3 is thus moved to the right. The air is also supplied through the branch conduit 3| to the outer end of the bore 20 of valve B, and, as soon as the working piston :3 reaches the end of its travel to the right, the pressure applied to the outer end of the piston 24 rises to a maximum. The piston 24 does not move, however, so long as the knob 21 is kept depressed because the pressure acting on the opposite side of the largerdiameter piston 23 exerts a considerably larger counterforce, the conduits I and 30 leading from the same air pressure source.

If now the press-knob 2? is released, the pressure in the cylinder l5 of valve A, in the conduit H, the bore 19 and the conduit 26 is exhausted through the outlet 29 leading from the impulse valve 28, with the result that the pressure acting on the outer end of the piston 24 predominates over that acting in the reverse direction and the valve member 22 moves to the right. In these conditions the bore l9 at the left of the piston 23 and the conduit Iii leading to the cylinder id of valve A is put into communication with the conduit 26 leading from the impulse valve 28. The air in the end of bore i9 at the right of piston 23 which was not exhausted before the said piston closed the outlet to conduit 26, escapes directly afterwards through the duct 34, which latter becomes uncovered by the piston 25. At the same time the duct 33 becomes blocked by the piston 24. In this position (i. e., with the valve member 22 to the right) the set of pistons in valve A are not affected and for this reason it remains in its leftward position.

The next time the press-knob 21 is pressed the air pressure is applied through the conduit 26 to the bore [9 at the left of the piston 23, and from there through the conduit it to the cylinder l4 at the left of control valve A. This causes the valve member 2 to move back to the right for returning the working piston l3 to the left, the pressure air at the left of the working piston and in the conduit 3| leaving through the conduit l0 and the outlet 8 of valve A. When the knob 21 is next released the cycle just described is repeated, although in the opposite direction.

From the foregoing it is clear that the control valve A and with it the working piston are moved alternately in both directions by the repeated pressing of the same valve knob. An important feature of the arrangement is that no change of position of the valve member 2 can take place before the working piston completes a working stroke to enable the operating pressure to build up behind it. Thus, for example and as shown, if the knob 21 is pressed for moving the working piston to the right and thereafter quickly released before the working piston finishes its stroke the cylinders 14 and I5 of valve A are both connected to exhaust, and valve 2 to 6 remains stationary. A new and immediate pressing of the knob 21 will not result in any reverse movement of the piston l3 because no sufficient pressure will have built up in conduit 3| to move the pistons 22 to 25. Such a sufiicient pressure build up only occurs when the stroke of the working piston is completed, and the knob 2! would have to be released, after the completion of the stroke of piston l3, before the piston set 22 to 25 could be operated to the opposite extreme for reversely operating the piston 13.

The arrangement according to the invention is also applicable for the giving of impulses for other purposes-for example, for controlling the operation of a single-acting piston with a spring return. Thus, if the piston l3 were to be spring biassed to the left on the drawing, it would only be necessary to close the conduit H between the cylinder 12 and the branch conduit 32 whereupon the arrangement would function in the above-described manner with the difference that the time for the building up of the pressure in the conduit 32 would be shorter. That, however, could be adjusted by leading the conduit 32 through a container of predetermined volume for slowing up the increase of pressure to be applied to the outer end of the piston 25 of valve B.

What we claim as our invention and desire to secure by Letters Patent of the United States is:

1. Control means for a double-acting pressure responsive device comprising two co-acting control valves each having a valve member which is slidable in a co-acting cylinder, and each having cylinder chambers at the ends of the valve member to alternately receive fluid pressure from an appropriate source for actuating the valve member in opposite directions, one of the control valves controlling two outlets which are respectively connected to the pressure-responsive device to selectively actuate it, the other of the control valves controlling two outlets connected respectively to the cylinder chambers at the ends of said one control valve, and a single impulse valve connected to an inlet of said second control valve and to the source of fluid pressure, the impulse valve when unactuated connecting said inlet to an exhaust conduit and on being operated supplying fluid pressure to one or other of the outlets of said other control valve dependently upon the position of the valve member of said other control valve, the outlets of said one control valve also being respectively connected to the cylinder chambers at the ends of said other control valve, an intermediate portion of said valve member of said other control valve for controlling said outlets, said intermediate portion being of greater diameter than the ends of said valve member and being positioned to be subjected to said fluid pressure when said impulse valve is operated, said fluid pressure supplied by said impulse valve holding said intermediate portion against a bias supplied by fluid pressure acting on one of said end portions, said bias mov ing said valve member of said other control valve to its other position when said impulse valve is released.

2. Control means, according to claim 1, characterised in that the cylinder of said other control valve, placed between the impulse valve and said one control valve, contains a central bore which at its ends is continued by two axiallydirected bores of smaller diameter, which constitute the said cylinder chambers for the said other valve, the valve member thereof consisting of a rod supporting a piston in the central bore together with two end pistons fitting in the two smaller bores, whilst the impulse valve is connected to approximately the middle of the central bore at the ends of which are the two said outlets.

3. Control means, according to claim 2, characterised in that both of said end pistons are arranged in their extreme inner positions to block said exhaust ports which otherwise communicate 5 with the ends of said central bore.

References Cited in the file of this patent UNITED STATES PATENTS

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