US3769994A - A load insensitive time delay relay - Google Patents

Abstract

A time delay relay for compressible fluid operated systems which is insensitive to variations in relay load resistance and which includes an enabling vent port closing diaphragm responsive directly to a signal pulse together with an operating fluid control vent closing diaphragm responsive to the enabling vent closure and to the passage of a divided portion of the signal pulse fluid through time delay means. The operating air is either vented to or augmented from ambient air or the atmosphere depending on load resistance.

Description

United States Patent 11 1 Hirao Nov. 6, 1973 [54] A LOAD INSENSITIVE TIME DELAY RELAY 3,653,408 4/1972 Coiner 251/6l.1 X

[76] Inventor: Toshiro Hirao, Kamoi-cho,

M d Yokohama-Shh Primary Examiner-Alan Cohan K n g w Japan Att0rney.loseph M. Lane et al. 22 Filed: July 18, 1972 Appl. N0.: 272,870

Foreign Application Priority Data July 26, 1971 Japan 46/55208 US. Cl 137/84, 251/28, 25l/6l.l Int. Cl. G05d 16/00 Field of Search 137/84, 82;

References Cited UNITED STATES PATENTS 7/1970 German 251/61.1 x

[57] ABSTRACT A time delay relay for compressible fluid operated systems which is insensitive to variations in relay load resistance and which includes an enabling vent port closing diaphragm responsive directly to a signal pulse together with an operating fluid control vent closing diaphragm responsive to the enabling vent closure and to the passage of a divided portion of the signal pulse fluid through time delay means. The operating air is either vented to or augmented from ambient air or the atmosphere depending on load resistance.

6 Claims, 6 Drawing Figures PATENTEDNUY 6 ms OUTPUT FLOW R n UKDmWmWE .SnFDO LOAD INSENSITIVE TIME DELAY RELAY BACKGROUND OF THE INVENTION This invention relates to a load insensitive time delay relay and particularly to an all air type time delay relay which provides a substantially constant output regardless of the varying loads.

' Heretofore, relays of the type referred to have suffered from the disadvantage that the output pressure they provide will vary widely with the varying loads connected to the output side of the relay. Such output pressure variation has been due primarily to the use of simple orifice restrictor in the supply side of the relay. In this respect, taking a simple fluid element as an example of the load connected to the output side of the relay, the output pressure of the relay or correspondingly, the resistance of the load, varies with the number of the fluid elements connected to the output side of the relay. Specifically, an increase in the number of fluid elements will increase'the demand for output air from the relay and cause a reduction in relay output pressure. Accordingly, the resultant-output pressure may sometimes be lowered below the switching pressure for the fluid elements, thus providing difficulties in the practical application. To avoid the above mentioned disadvantage, there has been proposed, in an attempt to provide a load insensitive time delay relay, the

incorporation in a conventional'relay of an auxiliary fluid element on its output side. However, this approach has failed to provide a complete solution to the problem because the required complicated construction and resulting increased risk of malfunction.

Accordingly, it is a principal object of the present invention to provide an all air type load insensitive time delay relay which avoids the disadvantages of relays heretofore available while also providing a simple but reliable time delay relay.

I SUMMARY OF THE INVENTION According to the present invention, a load insensitive time delay relay is provided which includes a combination of diaphragms, partition walls and nozzles each provided in said partition walls together with divided input signal passageways, one of which involves time delay means, the diaphragms each being adapted to respond to the input signal pressures. The input flow passageway to this relay involves a nozzle type restrictor and a bleed restrictor adapted to suck the air from or bleed the air to the atmosphere depending on the magnitude of the load resistance being applied to the relay. In this way the output pressure is mantained substantially constant thus providing reliable load insensitive characteristics for a relay of this type.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic diagram illustrating the major operating components and air flow paths of a load insensitive time delay relay according to the invention;

FIG. 2 is a vertical cross section through a physical embodiment of the relay;

FIG. 3 is a plan view of the relay as viewed from the line Ill-III of FIG. 2;

FIG. 4 is across-section taken on line IV-IV of FIG.

2 but showing in plan the surface of a lower component of the relay;

FIG. 5 is an enlarged fragmentary cross sectional view taken on line VV of FIG. 3 and showing a noz- DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, a time delay relay incorporating the invention is provided with an air supply passageway or inlet 1 for passing a uniform supply of operating air to an output port 5 by way of a nozzle type restrictor 2, a bleed restrictor 3 and a passageway 4. A control vent port in the form of a nozzle orifice 6 is provided in a partition wall 22 which is bounded on one side by the passageway 4 and on the other side by a chamber established in part by an impermeable primary control diaphragm 8. Located intermediate the diaphragm 8 and said partition wall 22 in terms of air flow and in a peripheral wall of the relay body is a bleed port 9 adapted to bleed the air passing through the nozzle 6 to ambient air or to the atmosphere. The side of the diaphragm 8 opposite from the side thereof facing the partition wall 22 is spaced from and forms a chamber with a partition wall 10 having a nozzle or enabling vent port 12 located substantially in the center thereof. A secondary enabling diaphragm II is positioned under the partition wall 10. Also, a bleed port I3 is provided in the peripheral wall of the relay intermediate the diaphragm l1 and the partition wall 10.

The side of the diaphragm 1 1 opposite from the partition wall 10 defines a further closed chamber exposed directly to control air passing from a first input signal port 14. There is provided in the peripheral wall of the relay a second input signal port 15 which is positioned intermediate the partition wall 10 and the diaphragm 8. An input signal passageway 16 for the relay is divided into two passageways, i.'e., one I7 communicating directly with port 14 and the other 18 communicating with port 15 by way of a variable restrictor 19 and an accumulator or capacitor 20, such that the input signal to be fed through said passageway 18 will be delayed for an adjustably predetermined period of time with respect to a pressure signal at the input 16.

As shown most clearly-in FIGS. 2 and 5 the restrictor 2 is in the form ofa nozzle orifice of a small diameter, the orifice being open on one side to a low pressure region 21 which has a diameter greater than that of the orifice. The bleed restrictor 3 is disposed in normal or perpendicular relation to and immediately downstream from the restrictor 2. Also the bleed restrictor forms an orifice of larger diameter than the orifice 2 and is in fluid communication with the low pressure region 211 on one side and with the atmosphere on the other.

In operation, operating air enters the air supply passageway I and is discharged, if a load is connected to the output port 5, via the nozzle or vent port 6, through the bleed port 9 and to the atmosphere. This causes the pressure at the output port 5 to be substantially equal to the atmospheric pressure. When an input signal pulse is fed to the passageway 16 and the signal divided as described above, the diaphragm 11 will be moved upwardly against and close the nozzle 12 by virtue of the direct passage of air through the one of the two divided signal pulse passageways including the port 14. Thereafter, signal air will pass through the other of the divided passageways; namely, the variable restrictor I59 and accumulator 20 to the lower side of the diaphragm. After a certain lapse of time the diaphragm 8 will be moved so that the nozzle 6 becomes blocked. As a result of this blocking of the nozzle 6, operating air in the passage 4 will be emitted through the outlet port of the relay. Thus it will be seen that with operating air being introduced to the inlet 1 at a relatively uniform rate, an output pressure signal will be emitted at the outlet port 5 a predetermined time after the delivery of a signal pulse to the passageway 16.

As can be seen most clearly in FIG. 5, the operating air passageway l of time delay relay of the present invention contains a nozzle type restrictor 2 and a bleed restrictor 3 in advance of the passageway 4 and outlet port 5. Therefore, when the load resistance at the outlet port 5 is abnormally high, then the operating air, which has issued through the restrictor or nozzle 2, will be discharged in part through bleed restrictor 3 to the atmosphere, thus preventing the increase in the output pressure. On the other hand, when the load resistance is abnormally low, there will develop eddy currents within the low pressure region 21 on the lower comers thereof, such that the ambient air is sucked through the bleed restrictor 3, thus increasing the quantity of air flow to be supplied to the load. This operation helps to prevent a decrease in the output pressure in any appreciable amount. It is to be noted that the low pressure region 21 as referred to above will not develop in the case of high load pressures due to the resultant increased static pressure, so that the suction of the ambient air through the bleed restrictor 3 will not take place under such condition.

In this manner, when the load resistance on the output side is abnormally high, then part of the air being supplied will be discharged to the atmosphere through the bleed restrictor 3, with the result that the output pressure is not increased to a point at or above the pressure of the air being supplied. Conversely, when the load resistance is abnormally low, then the atmosphere is sucked inside through the bleed restrictor 3 with the resultant prevention of the decrease in the output pressure. It may be readily appreciated from the description given thus far that the time delay relay of the present invention will be insensitive to the varying loads.

in the absence of a signal in the passageway 16, the air under pressure acting on the diaphragm 11 will instantaneously be released through the port 14. Then, the diaphragm 11 will be restored to the initial condition, thus opening the nozzle 12. This in turn causes the air under pressure acting on the diaphragm 8 to be released to the atmosphere through the nozzle 12 and bleed port 13, such that the diaphragm 8 will be restored to the initial condition. Accordingly, the pressure at the output port 5 will be maintained at atmospheric pressure.

As is apparent from the foregoing, since the time delay relay of the present invention incorporates in the passageway 4 a nozzle type restrictor 2 and a bleed restrictor 3 which is in communication with ambient air or the atmosphere, the suction or discharge of the ambient air in accordance with the magnitude of a load may be accomplished, while maintaining the output pressure substantially constant i.e., providing a desired time delay relay insensitive to the varying load conditions. To more clearly illustrate the superior performance of the time delay relay of the present invention, FIG. 6 is provided, in which as indicated by a curve A,

the output pressure and output flow rate characteristics of the conventional orifice type relay vary in a wide range with the varying load (i.e., varying flow rate), whereas as indicated by the curve B, the variation in the output pressure in the time delay relay of the present invention remains substantially small.

Although the embodiment thus described is preferred, it is to be understood that it is exemplary only, not limiting, and that the true spirit and scope of the present invention will be determined by reference to the appended claims.

I claim:

1. A load insensitive relay for air or other compressible fluid operated systems, said relay comprising:

means defining an operating air passageway including an inlet to which operating air is supplied, an outlet from which such air is discharged to the load of the relay and a normally opened control vent port intermediate said inlet and outlet;

a primary control member movable from a normal position spaced from said control vent port to a seating position blocking said control vent port;

means to move said control member to said seating position in response to a fluid signal pulse;

said operating air passageway including at a location between said inlet and said control vent, a nozzle type orifice to which operating air is passed and a bleed restrictor disposed immediately downstream from and normal to said restricted orifice, said restricted orifice and said bleed restrictor cooperating to discharge operating air to or to suck air from the atmosphere depending on the resistance of the load to which said operating air outlet port is connected.

2. A load insensitive time delay relay for air or other compressible fluid operated systems, said relay comprising:

means defining an operating air passageway including an inlet to which o'perating air is supplied, an outlet from which such air is discharged to the load of the relay and a normally opened control vent port intermediate said inlet and outlet;

a primary control member movable from a normal position spaced from said control vent port to a seating position blocking said control vent port;

means defining with said control member a chamber having an inlet and a normally opened enabling vent port;

an enabling member movable between a normal position spaced from said enabling port to a seating position blocking said enabling vent port;

means defining with said enabling member a closed chamber having an inlet port on the side of the said enabling member opposite from the side thereof which seats against said enabling vent port; and

means to supply control fluid signals to said members, respectively and including first and second divided passageways supplied by common control signal source, said first passageway being connected to the inlet of said closed chamber for moving said enabling member to its seating position against said enabling vent port, said second signal passageway including time delay means and being connected to the inlet port of the chamber defined with said control member to close said control vent port after said enabling vent port has been closed orifice, said restricted orifice and said bleed restrictor cooperating to discharge operating air to or to suck air from the atmosphere depending on the resistance of the load to which said operating air outlet port is connected.

5. The apparatus recited in claim 4 wherein said restricted orifice is defined by a nozzle.

6. The apparatus recited in claim 2 wherein said members are fluid impermeable flexible diaphragms.

Claims (6)

1. A load insensitive relay for air or other compressible fluid operated systems, said relay comprising: means defining an Operating air passageway including an inlet to which operating air is supplied, an outlet from which such air is discharged to the load of the relay and a normally opened control vent port intermediate said inlet and outlet; a primary control member movable from a normal position spaced from said control vent port to a seating position blocking said control vent port; means to move said control member to said seating position in response to a fluid signal pulse; said operating air passageway including at a location between said inlet and said control vent, a nozzle type orifice to which operating air is passed and a bleed restrictor disposed immediately downstream from and normal to said restricted orifice, said restricted orifice and said bleed restrictor cooperating to discharge operating air to or to suck air from the atmosphere depending on the resistance of the load to which said operating air outlet port is connected.

2. A load insensitive time delay relay for air or other compressible fluid operated systems, said relay comprising: means defining an operating air passageway including an inlet to which operating air is supplied, an outlet from which such air is discharged to the load of the relay and a normally opened control vent port intermediate said inlet and outlet; a primary control member movable from a normal position spaced from said control vent port to a seating position blocking said control vent port; means defining with said control member a chamber having an inlet and a normally opened enabling vent port; an enabling member movable between a normal position spaced from said enabling port to a seating position blocking said enabling vent port; means defining with said enabling member a closed chamber having an inlet port on the side of the said enabling member opposite from the side thereof which seats against said enabling vent port; and means to supply control fluid signals to said members, respectively and including first and second divided passageways supplied by common control signal source, said first passageway being connected to the inlet of said closed chamber for moving said enabling member to its seating position against said enabling vent port, said second signal passageway including time delay means and being connected to the inlet port of the chamber defined with said control member to close said control vent port after said enabling vent port has been closed and thereby cause an increase in pressure at the outlet of said operating fluid passageway.

3. The apparatus recited in claim 2 wherein said time delay means comprises a variable restrictor in series with an accumulator in said second signal passageway.

4. The apparatus recited in claim 2 wherein said operating air passageway includes between said inlet and said control vent, a restricted orifice to which operating air is passed and a bleed restrictor disposed immediately downstream from and normal to said restricted orifice, said restricted orifice and said bleed restrictor cooperating to discharge operating air to or to suck air from the atmosphere depending on the resistance of the load to which said operating air outlet port is connected.

5. The apparatus recited in claim 4 wherein said restricted orifice is defined by a nozzle.

6. The apparatus recited in claim 2 wherein said members are fluid impermeable flexible diaphragms.

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