US2829858A

US2829858A - Pneumatic toggle relay with controlled positive feed back

Info

Publication number: US2829858A
Application number: US529219A
Authority: US
Inventors: Ray S Williams
Original assignee: Hagan Chemicals and Controls Inc
Current assignee: Hagan Chemicals and Controls Inc
Priority date: 1955-08-18
Filing date: 1955-08-18
Publication date: 1958-04-08
Anticipated expiration: 1975-04-08

Description

April 8, 1958 R. s. WILLIAMS 2 PNEUMATIC TOGGLE RELAY WITH CONTROLLED POSITIVE FEED BACK Filed Aug 18, 1955 INVENTOR. RAY 5. WILLIAMS PNEUMATIQ TOGGLE RELAY WITH CON TRDLLED PQSITIVE FEED BACK Ray S. Williams, Orrville, Ohio, assignor to Hagan Chemicals & Controls, Inc., a corporation of Pennsylvania Application August 18, 1955, Serial No. 529,219

Claims. (Cl. 251--28) This invention relates to pneumatic toggle relays having valves which are either on or off or vice versa, as distinguished from modulating relays.

An object of this invention is to provide a pneumatic toggle relay having a main valve which is either open in supply position, or in off and exhaust position, or vice versa, that is actuated to one or the other of those positions by means of a pilot valve controlled jointly by a signal responsive diaphragm, a positive feed back diaphragm and an adjustable yielding means for urging said diaphragms in such a direction that the pilot valve is urged towards one of its positions, i. e., on or $iofil Another object of the invention is to provide a toggle relay in which the toggle action is controlled by the positive feed back.

A further object is to provide a toggle relay having a pilot valve system which develops a high gain and which results in a relatively narrow on and oit signal pressure band and a sharp toggle action with a relatively small amount of positive feed back.

A still further object is to provide a toggle valve as above set forth in which the feed back is adjustable by a fractionating system, whereby. the on and off toggle pressure range may be controlled or adjusted easily and conveniently.

The above and other objects and features of the invention will be apparent to those of ordinary skill in the art to which the invention pertains from the following description and the accompanying drawing.

Inthe drawing:

Figure 1 is a more or less diagrammatic view of a pneumatic toggle valve embodying a form of the invention; and

Fig. 2 is a view in vertical section of a more fully 7 developed embodiment illustrating a more. nearly commercial form of the toggle relay.

As illustrated in Fig. '1, the toggle relay comprises a sectional housing-provided with a main supply and exhaust valve assembly 1, a pilot valve 2tfor supplying control pressure to the operating diaphragm 3 of the assembly 1, an input signal pressure responsive diaphragm 4, a feed back diaphragm 5, and an adjustable yielding means 6 for urging the pilot valve 2 towards one of its control positions. The control positions of valve 2 are on or supply position and ,oii or exhaust position. j j

The diaphragms 4 and 5 and the means 6 are coupled by a linear linkage 7 to valve 8 of pilot valve 2'.

The yielding means 6 is adjusted to exert a predetermined force. Thealgebraic sumof that force and the forces developed'by the signal input pressure 'and the feed back pressure on diaphragms 4 and 5 determines whether valve 8 is actuated to exhaust or to on position, when the signal inputpressure increases to' or decreases below a predetermined value. If valve 8 isactuated to on position, main valve 1 is opened to conect a source of supply of operating fluid, such as compressed air,:toa i nited States Patent Q supply line 10; but if actuated to exhaust position, main valve ll closes and exhausts the pressure from the supply line it). Thus, the main valve is toggled either from on or open position to a closed and exhaust position, or vice versa, depending on the direction in which the signal pressure acts on diaphragm 4, the force exerted by the means 6, and the adjustment of the feed back to diaphragm 5. Thus, it is possible to have the main valve open in response to the signal pressure increasing to or above a predetermined value, or the main valve may be caused to close and exhaust the supply line in response to the signal pressure decreasing below a predetermined value, as will be explained infra.

The main valve and operating diaphragm assembly The main valve assembly 1 comprises the operating diaphragm 3, the marginal edge of which is clamped between housing sections 12 and 13 to provide a chamber 14 to which valve 2 supplies operating pressure. Diaphragm 3 operates a valve 15 having a ball valve 16 for controlling an inlet port 17 in a housing cap section 18. Pressure, such as compressed air, is supplied to the port 17 by a supply pipe 19. Valve 15 is also provided with a ball valve 26 that controls an exhaust port 21 that communicates with the atmosphere through an exhaust passage 22 in a link or strut 23. The strut 23 is secured at its exhaust port end to a diaphragm 24 which is of smaller effective area than the diaphragm 3. The marginal edge of diaphragm 24 is clamped between the cap section 18 and a partition 25. The partition 25 is provided with a central aperture through which the strut 23 extends. The diaphragm 3 is urged upwardly by means of aspring 26 disposed between the partition 25 and a bearing plate 27 in the center of the diaphragm 3. When diaphragm 3 is urged downwardly by pressure supplied to the chamber 14, diaphragm 24 is flexed towards the inlet port 17 whereby the exhaust port is closed, but the inlet port 17 is opened. Pressure is then admitted into the chamber 28 and thence to a supply line ltl leading to a device or apparatus which depends upon the supply of that pressure for its operation. When the operating pressure on diaphragm 3 is decreased to 'a value at which the inlet port 17 is closed and the exhaust port is opened, the pressure in the supply pipe 10 is exhausted to the atmosphere, whereupon the apparatus controlled by that pressure is shut down.

As will be shown infra, the toggle relay is so constructed that the inlet port 17 will either be opened with the exhaust port closed, or the inlet port will he closed and the exhaust port 21 opened, depending upon the adjustment of the component parts to be hereinafter described. Therefore, the relay is not a modulating relay but an on and ofi relay and is therefore termed a pneumatic toggle relay valve.

The pilot valve The signal input responsive diaphragm The signal input responsive diaphragm 4 is clamped at its marginal edge between housing sections 43 and 44. Chambers 45 and 46 are formed on the opposite sides of diaphragm 4 by partitions 47 and 43, the mar- Tgins of which are clamped between housing sections 44 The body is provided with a flange 3 5 by which it

t

3 and 49, and

housing sections

43 and 37, respectively. As shown, the partitions 47 and 48 are provided with central apertures to accommodate the linear linkage 7. In order that the chambers 45 and 46 may be pressure tight and still accommodate the linkage 7, the space about the linkage 7 is sealed by means of sealing members, such as small bellows 50 and 51. As shown, the upper end of the bellows 50 is secured by welding or other suitable means, to the margin of the aperture in partition 47 and to a backing plate 52 on one side of the diaphragm 4. Similarly, the diaphragm 51 is secured at its upper end to a backing plate 54 on the under side .of the diaphragm and the lower end of the bellows 51 is secured, as by welding or otherwise to the margin of the aperture in partition 48. Thus, by means of the diaphragm 4, the partitions 47 and 48, and the bellows 50 and 51, pressure tight chambers 45 and 46 are formed. The linkage 7 is coupled to diaphragm 4 and to the valve 8 by means of link sections 56 and '7. The lower end of the link section 56 is provided with a reduced threaded portion 58 that passes through the backing plates 52 and 54 and the central portion of the diaphragm 4, and is threaded into the upper end of the link section 57. The threaded connection is such that the plates 52 and 54 may be drawn tightly against the diaphragm. The lower end of section 57 has a screw thread connection 59 with a stem 6t! on the valve 8.

The feed back diaphragm and leak-off assembly The feed back diaphragm and leak-off assembly comprises the diaphragm 5, the marginal edge of which is clamped between housing section 49 and a housing section 62. The central portion of the diaphragm 5 is backed on one side by a plate 63 and on the opposite side by a plate 64. The central portion of the backing plate 63 is provided with an internally threaded boss 64 for accommodating the threaded portion 65 ot the link section 56 which passes upwardly through plate 64 and the central portion of the diaphragm and the backing plate 63. A nut 66 is threaded up against the plate 64 so as to firmly clamp the central portion of the diaphragm 5. The diaphragm 5 and the partition 47 form a pressure tight feed back chamber 68.

Controlled feed back from the supply pipe is supplied to chamber 68 through a branch pipe 69, and a take-off pipe 70 leading to the interior of chamber 68. The portion of pipe 69 beyond the take-off pipe 70 is provided with an adjustable needle valve 71 through which pressure exhausts to the atmosphere at a rate controlled by the setting of the needle valve. Between pipe 10 and the take-off 70 is an orifice 72 in the branch pipe 69. The orifice 72 provides a pressure drop across it, depending upon the rate of discharge of air to the atmosphere through the needle valve 71. The relative setting of the needle valve 71 with reference to the particular orifice 72 selected will establish a pressure in the take-off pipe 70 that is a function of the relative pressure drops across the orifice 72 and the orilice 71. Thus the feed back pressure in chamber 68 may be adjusted and controlled. The feed back to chamber 68 acts in such a direction on diaphragm 5 that the feed back is positive. That is, it acts in a direction to move the valve 8 towards its open position.

The yielding means 6 The yielding'means 6 comprises a relatively strong compression spring 74 disposed between cap section 75 of the housing and the backing plate 63 of diaphragm 5, and an adjustable spring 76 that can be put in compression or tension in accordance with the particular operating characteristic required of the relay. As shown, the lower end of spring 76 is clamped by an annular ferrule 77 and a screw 78 to the upper end of the link section 56. The upper end of the spring 76 is clamped by an annular ferrule 79, to a support member 80carried by the lower end of a screw 81 that has screwthread engagement with a rotatable cap 82 supported by the upper end of a neck 83 which is part of the cap section 75. By relatively rotating the screw 81 and the cap 82, the spring 76 may be compressed, or it may be elongated to neutralize partially or fully the compression in spring 74.

Operation of the toggle relay valve Assuming that the signal input pressure is supplied to chamber 45 and that the relative tensions in

springs

74 and 76 are such that the spring force acts downwardly, that is, in a direction to urge valve 8 towards its inlet port 32 and away from the exhaust port 33, it will be apparent that the valve 8 is urged towards closed position, in which event, the operating supply pressure will be exhausted from chamber 14 and cause spring 26 to actuate the main valve to its closed position. The main valve 15 will then exhaust pressure from pipe 10, the branch pipey69, .and the take-ofi pipe 70. There fore, in order to toggle valve 15 to its oil? position, the valve 8 must be actuated to closed position when the signal pressure has increased in chamber 45 to a value sufiicient to overcome the net spring force of

springs

74 and 76 and the feed back pressure to chamber 68. As soon as thesignal pressure exceeds that requirement, valve 8 will be moved downwardly until it closes the inlet port 32 and opens wide the exhaust port 33. At that time the pressure in chamber 14 and acting on diaphragm 3 will be exhausted to the atmosphere, whereupon the main valve will be toggled closed, and the pressure in pipe 10 exhausted to the atmosphere through the exhaust port 21, as above described.

If the signal pressure is introduced to chamber 46, then it will be apparent that the valve 8 and the main valve will be actuated to wide open position, so long as the signal pressure in chamber 46 is above a predetermined value. When the signal pressure acts in chamber 46, the forces acting on valve 8 and developed by that pressure, will be in the same direction as the feed back acting on the diaphragm 5. The particular pressure at which valve 8 and the main valve 15 are toggled to closed position when the signal pressure decreases below that particular pressure, again depends upon the relative or net spring force of

springs

74 and 76, and the feed back pressure maintained in chamber 68. As stated above, the feed back in chamber 68 will be proportional to the pressure drops across orifice 72 and the orifice valve 71.

From the foregoing description of the device shown in Fig. 1, it is apparent that a toggle relay valve is provided .in which the main valve may be toggled from closed to open position in response to a signal pressure increasing to a predetermined value, or it may be toggled from an open position to a closed position in response to the signal pressure increasing from a minimum value to some predetermined higher value.

The toggle relay of Fig. 2

The toggle relay of Fig. 2 is shown inverted in position with respect to the toggle relay of Fig. 1, but that does not afiect its operation, as it may be mounted vertically or horizontally, as the requirements may dictate.

The relay of Fig. 2 is similar to the one shown and described in reference to Fig. 1, therefore, similar and corresponding parts have been designated by the same reference characters with primes afiixed.

The main difierences between the relay of Fig. 2 and that of Fig. '1 are in the construction of the main valve assembly 1', the construction of the pilot valve 2, and the-construction of the yielding means 6'.

The relay of Fig. 2 includes the housing sections 18, 43', 44',-49', 62' and 83', and in addition, housing sections 86, 87, and 88. The housing sections as shown are mounted tandemwise andsecurely bolted together. As

shown,

gaskets

89, 90 and 91 are provided between the housing sections 18' and 86, housing sections 88 and 43', and housing sections 44 and 49, respectively, to provide pressure tight joints at those locations.

The main valve of Fig. 2 comprises a main supply valve 92 that controls a supply port 93 formed in a plate 94 that is clamped between sections 18' and 86, a gasket 95 being provided to form a pressure tight joint. Valve 92 is urged toward the seat of port 93 by means of a compression spring 96. Valve 92 is provided with a depending cylindrical portion 97 that controls the exhaust of the supply port 98 to atmosphere, the supply port being the port which would be connected to the supply pipe of Fig. 1. The main valve includes a separate exhaust valve 100 that is carried by a diaphragm 101, the marginal edge of which is clamped between housing sections 86 and 87. The pressure supply, that is, the source of supply of pressure which is to be communicated through valve 92 to the supply port 98 is connected to a port 102 in housing section 88. The housing section 88 and the housing section 87 and the housing sections 86 and 18 are provided with communicating ports that form a passageway 103, leading to chamber 104 in housing section 18' on the inlet side of valve 92. The air supply to valve 92 passes through a passage 105 in section 86, and

passageways

106 and 107 to the supply port 98.

As shown, the exhaust valve 100 has a cylindrical portion 108 that is hollow and a square upper end upon which the portion 97 of valve 92 seats to close the exhaust port. The portion 108 is threaded to accommodate a clamping nut 110 having a retaining flange 111 therein for a compression spring 112. The lower end of the valve 100 has a head 113 having lateral passageways 114 leading to the space between diaphragm 101 and diaphragm 3'. A washer between the head 113 and the lower face of diaphragm 101 co-acts with the nut 110 to clamp the exhaust valve tightly to the central portion of the diaphragm 101. The spring 112 exerts a force tending to open the exhaust passage in the exhaust valve, but it is held closed by the pressure on the diaphragm 3, that pressure being suppliedby the pilot valve 2'. The space between

diaphragms

101 and 3 communicates with the atmosphere through an exhaust passage 117. It is through the exhaust valve and the exhaust passage 117 that the pressure in the supply pipe connected to the supply port 98 is exhausted when the main valve 92 closes.

The pilot valve 2' comprises a body 31 which is mounted in a bore 118 in the housing section 88. As shown, the body is provided with spaced annular grooves to accommodate sealing rings 119. The supply pressure at port 102 is communicated to the inlet of the valve 2' through a port 120. The body 31' is held in its proper position by means of a slotted spring 121. The inlet port for valve 2 is formed in a bushing 124. Valve 8 controls the inlet port or seat in the bushing 124 and the exhaust port in a bushing 124. The bushing 124, as shown, is adjustable in the body as it is screw-threaded into the same. Valve 8' is urged towards the exhaust port seat and bushing 124 by means of a spring 126. The outlet port of the body 31' communicates through a passageway 127 to the chamber 14 on the under side of diaphragm 3'. The exhaust port of valve 2' communicates with the atmosphere through a passageway 128 and a passageway 129 in the housing section 43.

The sealing bellows 51' is secured, as by welding, or otherwise, to an apertured plate 130 which is clamped between the housing section 88 and the housing section 43', a sealing ring 131 providing a pressure tight joint. The opposite end of the bellows 51' is secured, as by welding or otherwise, to a flanged cup 132. One end of the sealing bellows 50' is secured to an apertured plate 133, as by welding or other suitable means, which is clamped between housing section 49 and housing section 44', a sealing ring 134 being provided to form a pressure tight joint. The opposite end of the bellows 50 is secured to a flanged cup member 135, as by welding, "for example. The bottoms of the cup members 132 and 135 are apertured to receive a bolt 137. As shown, the bolt 137 is threaded into a sleeve 138, so that the cup members 132 and 135 are clamped firmly between the head 139 of the bolt and the sleeve 138. The head of the bolt 137 is connected by an adjustable coupling 140 to a stem 141 of the valve 8' so that the valve can be operated towards or away from the inlet and exhaust ports thereof.

The feed back diaphragm 5 is clamped at its central portion between the sleeve 138, a washer 141, and a flanged nut 142, that serves as a retainer for one end of the spring 74'. The nut 142 is threaded onto a bolt 143 that is threaded into the sleeve 138 and the nut 142, as shown, thereby to clamp tightly the central portion of the diaphragm and to thereby couple it to the valve 8'.

One end of spring 76' is secured to the end of bolt 143 and the other end is secured to a plug 144 anchored in the head 145 of an adjusting screw 146. The screw 146 passes through a nut 147 that is screwed into the neck 83'. as shown. The nut 147 is slotted, as at 148, to accommodate a screw 149 that guides the screw 146 and keeps it from turning when the adjusting nut 150 is turned to increase or decrease the tension in spring 76.

To provide for mounting the device of Fig. 2 on a panel, a nut 151 is provided and threaded onto the nut 147, so that if the nut 147 is passed through the aperture in a panel 152, it may be clamped thereto.

The feed back from the supply port 98 to the diaphragm 5' or to the chamber 68 is effected by connecting port 98 to a port 153 in housing section 49. The leak-ofi from the chamber 68 through the leak-off valve 71 may be effected by connecting port 154 of housing section 49' to a pipe provided with a needle valve as shown at '71 in Fig. 1. It is to be understood that the

pipeconnecting ports

93 and 153 will be provided with the orifice 72 of Fig. l.

The operation given for the device of Fig. 1 applies also to the relay of Fig. 2. If the signal pressure is supplied to chamber 45 through a port 155 of housing section 44 and the relay spring adjustments have been made as required, it follows that the signal pressure must increase from some low value to a higher value before the relay is toggled in a direction to close the "inlet port of the pilot valve 2 and thereby cause the main valve 92 to close and the exhaust valve 100 to open. Thus, with the signal pressure supplied to chamber 45 the toggling will be efiected by a closing of the main valve 92 when the signal pressure rises from one value to a higher value.

If the signal pressure is supplied to chamber 46 through port 155', it follows that the force of the pressure applied to diaphragm 4' will be in a direction to open the pilot valve 2 and supply pressure to the chamber 14' which opens the main valve 92. However, the main valve 92 will not open until the signal pressure has reached a pre-set value; and conversely, it will close if the signal pressure falls below that value. As in the case of the device shown in Fig. l, the device shown in Fig. 2 can be caused to toggle within a relatively narrow band of signal input pressure, depending upon the spring adjustments of the means 6' and the rate at which the pressure to the feed back chamber is leaked off to the atmosphere.

Having thus described the invention, it will be apparent to those skilled in the art, that various modifications and changes may be made in the illustrated embodiments thereof, without departing from either the spirit or the scope of the invention.

Therefore, what is claimed as new and desired to be secured by Letters Patent is:

. l. A pneumatic toggle device having a supply valve for controlling the supply of compressed fluid from a supply source to a supply line, a relay body having a v 7 plurality of tandem sections forming a plurality of chambers, diaphragms embodied in said chambers, a first one of said diaphragms operating said supply 'valve, an exhaust valve associated with said supply valve for exhausting the supply line when the supply valve closes, a pilot valve having open and closed positions for controlling the supply of operating pressure to the main and exhaust valve operating diaphragm, a second and a third one of said diaphragms being operatively connected to the pilot valve to actuate the same, the second of said diaphragms being responsive to an input signal pressure, and the third onebf said diaphragms having a feed-back connection to the output of said main valve, an orifice in said feed-back connection, an outlet leak-off connection communicating with the pressure on said third diaphragm and having an orifice therein for controlling the rate of leak-off whereby the pressure acting on the third diaphragm is proportional to the pressure drops across said orifices, and means for adjustably urging the second and third diaphragms in a direction in which said pilot valve is actuated towards one of its control positions, said second and third diaphragms developing forces that are algebraically additive and when the sum thereof is less than the urging forces of said yielding means, the pilot valve is actuated to one of said positions and when the forces of the pressures acting on said diaphragms exceed the yielding means, the pilot valve is actuated to the other of its positions, the orifices in the pressure connection from the outlet of the main valve to the third diaphragm controlling the relation of the signal pressure and the pressure on the third diaphragm at which the pilot valve and the main and exhaust valves are actuated t to one or the other of their controlling positions.

2. A toggle device as in claim 1 in which means are provided for so applying the signal and feed-back pressures to the third diaphragm that the forces of said signal and feed-back pressures oppose each other and causing the pilot valve to be closed when the signal pressure exceeds a predetermined value, thereby exhausting the pressure on the main valve operating diaphragm, closing the same, and opening its exhaust valve.

3. A toggle device as in claim 1 in which means are provided for so applying the signal and feed-back pressures that the forces of said signal and the feed-back pressures exerted on said third diaphragm act in the same direction and actuate the pilot valve from closed to open position in response to the signal pressure rising to a predetermined value.

4. A toggle valve as in claim 1 in which means are provided forso applying the signal and feed-back pressures that the forces developed by said signal'and feedback pressures on the third diaphragm act in opposition to each other and cause the pilot valve to be actuated from open to closed' position in response to the signal pressure decreasing below a predetermined value.

5. A pneumatic toggle device having a main valve and an exhaust valve for supplying pressure to a supply line when the main valve is open and the exhaust valve is closed, and for exhausting the supply pressure when the main valve is closed and the exhaust valve is open, means urging the main valve to closed position and the exhaust to open position, said device having a chamber and a flexible member therein for operating said main valve to open position while holding the exhaust valve closed, a pilot valve for supplying operating pressure'to or exhausting pressure from said chamber, said device having a signal input chamber provided with a diaphragm which divides said chamber into compartments, one on each side thereof, to either of which a signal pressure may be supplied, said device having a feed-back chamber and a diaphragm therein, a feed-back connection from the outlet of the main valve to the feed-back chamber and a leak-01f connection therefrom, an orifice in the feed-back connection and an orifice in the leak-off connection, an adjustable yielding means and means connecting the signal input and feed-back diaphragms and the yielding means to the pilot valve, the yielding means normally urging the pilot valve to one or the other of said supply and exhaust positions, the force of the pressure on the feed-back diaphragm and the net force of the yielding means causing the signal pressure diaphragm to close or open the main valve at pre-set input signal pressures.

7 References Cited in the file of this patent UNITED STATES PATENTS