US3896852A

US3896852A - Time delay valve

Info

Publication number: US3896852A
Application number: US422332A
Authority: US
Inventors: Lloyd H Holmes
Original assignee: E Systems Inc
Current assignee: Raytheon Co
Priority date: 1973-12-06
Filing date: 1973-12-06
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29
Also published as: GB1448929A

Abstract

A time delay is provided in a control system by a fluid responsive timing mechanism including an on/off slider valve. The slider valve of the timing mechanism is spring biased into an off position in one chamber of a housing that, in one embodiment of the invention, also includes a system control valve. A trigger for moving the slider valve is in contact with one end thereof and actuated by fluid pressure acting on a spring biased piston actuator in a second chamber of the housing. Fluid pressure applied to the spring biased piston activates the trigger to move the slider valve from the normal off position to an open position. The time required for the piston to activate the trigger is controlled by an orifice in a fluid line to the piston. The system control valve operates in a third chamber of the housing to control fluid to the piston actuator and also control fluid to the on/off slider valve. The system control valve provides fluid flow from a source proportional to a mechanical input displacement of a control slider valve.

Description

United States Patent Holmes 1 1 TIME DELAY VALVE Primary ExaminerAlan Cohan Assistant ExaminerGerald A. Michalsky [75] Inventor 6 H olmes a a e 1 y Attorney. Agent, or firm-Robert W. Wilder;

Richards. Harris & Medlock [73] Assignee: E-Systems, lnc., Dallas, Tex.

22 Filed: Dec. 6, 1973 [57] ABSTRACT [21] APP. NOJ 422,332 A t1me delay is prov1ded in a control system by a flu1d responsive tlmmg mechanlsm 1nclud1ng an on/off slider valve. The slider valve of the timing mechanism 1 is spring biased into an off position in one chamber of 91/ 6 /613; 137/628 a housing that, in one embodiment of the invention,

[51] Int. Cl. F151) 13/042; F15b 21/10 also includes a system control valve, A trigger for [58] Field Of Search 91/38, 447, 448; moving the slider valve is in Contact with one end l37/596.l4, 613, thereof and actuated by fluid pressure acting on a 625.63, 251/25 spring biased piston actuator in a second chamber of the housing. Fluid pressure applied to the spring bi- [56] References Cited ased piston activates the trigger to move the slider UNITED STATES PATENTS valve from the normal off position to an open position.

2,394,074 2/1946 Kilian 91/38 x T time required Piston acfivate the F 3,064,626 11/1962 Kufel 91/38 18 Controlled y an Oflfice a mud lme t0 the P 3,563,775 3/1971 Greenberg et 251 25 X The system control valve operates in a third chamber 3,605,554 9/1971 Philbrick 91/38 of the housing to control fluid to the piston actuator and also control fluid to the on/off slider valve. The

FOREGN PATENTS OR APPLICATIONS system control valve prov des fluld flow from a source proportional to a mechanical mput displacement of a 1,922,073 ll/l970 Germany 91/447 control Slider valve 9 Claims, 4 Drawing Figures I IO 96 //0 .9 4 IQ4 9 8 78 Q6 1% \l i F 80 I00 JU ir i 6O 62 y 34 36 :11: I: 58 W 1 t i 2 42 32 43 44 4o 45 TIME DELAY VALVE This invention relates to time delay apparatus for controlling the flow of fluid in a control system, and more particularly to fluid operated time control apparatus utilizing system fluid pressure in a timing actuator.

Such a fluid time delay apparatus may be used for supplying a fluid pressure through a pair of outlet conduits alternately to opposite sides of a double acting piston actuator. The direction of primary fluid flow through the time delay apparatus to the actuator is established by a system control valve responsive to a mechanical input. The same system control valve also establishes a fluid flow to the actuator of the time delay apparatus.

Heretofore, many time delay mechanisms used in fluid control systems required a separate source of energy to activate the timing function. This separate source of energy may be a mechanical displacement, an electrical signal or a fluid signal established by a separate subsystem. In any such system requiring a separate energy source for the time delay mechanism, reliability is adversely affected by the increased complexity of the system. Further, an operator of a control system incorporating such external source activated timing mechanisms is required to supervise the operation of additional equipment, thus significantly increasing the complexity of the system operation and further reducing reliability by increasing the possibility of human error.

A feature of the present invention is to provide a time delay mechanism utilizing as an activating source the same fluid source for the main control system. Further, the time delay mechanism is actuated by the same system input that controls the primary fluid flow to the control device. Another feature of the present invention is to provide a reliable timing mechanism utilizing fluid pressure from a central source and controlled by the same input that controls the main system.

Still another feature of the present invention is to provide a novel and improved time delay mechanism for use in a fluid system and which may be connected in the system between a system control valve and a fluid actuator or valve to provide a preselected time delay. Further, the time-out cycle is not initiated until the pressure is released at the primary source by the system control valve.

As mentioned, primary fluid pressure is supplied through the time delay mechanism of the present invention through its outlet conduits alternately; the time delay in each direction may be the same or a preselected difference in the timing function is within the scope of the present invention.

In accordance with one embodiment of the invention, a time delay mechanism for controlling a fluid flow in a control system includes a secondary slider valve movable between an open position and a closed position for controlling a fluid flow from input lines to output lines, the latter as part of the fluid control system. A trigger is coupled to the secondary slider valve to produce movement thereof from the closed position to the open position and this trigger is activated by an actuator responsive to fluid pressure. A primary slider valve for controlling a fluid flow to the input lines of the secondary slider valve from a fluid source also controls a flow path to the trigger actuator from the source. An orifice in a line from the source to the trigger actuator establishes a time delay between the movement of the primary slider valve and movement of the secondary slider valve.

In accordance with one embodiment of the invention, both the secondary slider valve and the primary slider valve are incorporated into a single housing structure and the primary slider valve includes lands for controlling the system control pressure and additional lands for controlling a fluid to the trigger actuator from the fluid source. In an alternate embodiment of the invention, the secondary slider valve and the associated trigger and actuator are part of a housing separate from the primary slider valve. By locating an orifice in lines from the primary slider valve to the actuator of the timing mechanism a different time delay may be established varying with the inputsignal to the primary slider valve.

A more complete understanding of the invention and its advantages will be apparent from the specification and claims and from the accompanying drawings illustrative of the invention.

Referring to the drawings:

FIG. 1 is a schematic of the time delay mechanism of the present invention as part of a fluid control system coupled to a double acting piston actuator and responsive to a mechanical input signal;

FIG. 2 is a sectional view illustrating an embodiment of the invention wherein the main control valve and the time delay mechanism are incorporated into a single housing structure;

FIG. 3 is a sectional view of a portion of the housing of FIG. 2 illustrating the timing mechanism after a time-out delay where the secondary slider valve of the timing mechanism has been moved from a closed position to an open position; and

FIG. 4 is an alternate embodiment of the present invention wherein different time delays are provided depending on the direction of the mechanical input signal and where the timing mechanism and the main control valve are provided as separate elements of the control system.

Referring now to the drawings, and initially to FIG. 1, there is illustrated a hydraulic system including a valve assembly 10 embodying the time delay mechanism of the present invention. In this embodiment of the invention, the valve assembly 10 includes both the timing mechanism and the main control valve for establishing a fluid flow to a double acting piston actuator 12 coupled by means of a connector 14 to an element to be controlled such as the control surfaces of an aircraft. The hyraulic system for providing fluid to the actuator 12 includes a pump 16 connected to supply pressurized fluid to the valve assembly 10. Fluid delivered by the pump 16 to the valve assembly 10 is provided from a reservoir 18 in accordance with standard procedures. Although the source of pressurized fluid is the pump 16, it should be understood that any other source of fluid could be utilized.

In the hydraulic control system of FIG. 1, pressurized fluid from the pump 16 is transmitted to the valve assembly l0 and proportionally controlled in accordance with a mechanical input signal applied to a connector 20 in either a forward or reverse direction as indicated by the arrow 22. Fluid from the valve assembly 10 is transmitted to the actuator 12 and returned therefrom by means of conduits 26 and from the assembly 10 to a reservoir 30 by means of conduits 28.

Referring now to the construction of the valve assembly as shown in FIG. 2, the mechanical input signal applied to the connector positions a control slider valve 32 movable in a primary bore 34 of a housing 36. Communicating with the bore 34 are inlet

passages

38 and 40 connected to the conduits 24 from the pump 16. Also communicating with the bore 34 are discharge passages 42-45 that connect to the conduit 28. Opposite the passage 40 in the area between the

passages

44 and 45 are

control passages

46 and 48 also communicating with a secondary bore 50 of the time delay mechanism. Opposite the passage 38 in the area between the

passages

42 and 43 are

actuator passages

52 and 54 that also communicate with an actuator bore A valve member 58 is slidably received within the bore 34, and is provided with

pressure lands

60 and 62 positioned on the member 58 in the area of the

passages

38 and 40, respectively. Also provided on the valve member 58 are

return lands

64, 66, and 68; the land 64 controls fluid through the passage 42, the land 66 controls fluid through the

passages

43 and 44 and the land 68 controls fluid through the passage 45. It will be readily understood that if it is desired to alter the characteristics of the control valve 32, the relative sizes of the lands on the valve member 58 may be changed to provide increased or decreased sensitivity to an input signal applied to the connector 20.

A valve member 70 is slidably received within the bore 50 of the time delay mechanism and is provided with

lands

72, 74 and 76. The lands 72 and 74 provide a fluid chamber within the bore 50 between the control passage 46 and an outlet passage 78 communicating with the bore and the

lands

74 and 76 provide a chamber betwen the control pasage 48 and an outlet passage 86. The land 74 controls fluid flow through the control passage 46 and the land 76 controls flow through the passage 48.

Extending to the right of the land 76 on the valve member 70 is a guide 80 with a collar ring 82 secured thereto. A spring 84 exerts a force on the ring 82 to bias the valve member 70 to the left in a position to close off the

passages

46 and 48 by means of the

lands

74 and 76, respectively.

In contact with the valve member 70 at the land 72 is a trigger 88 slidable in a channel 90 communicating with both the

bores

50 and 56. The trigger 88 extends through the channel 90 into the bore 56 and is sized with respect to the channel to provide an unrestricted movement thereof. The operating fluid in the bore 56 provides a lubricating film to insure a smooth operation of the trigger 88 to move the valve member 70 from the closed position as illustrated in FIG. 2 to an open position as illustrated in FIG. 3. Excess fluid from the bore 56 leaking into the bore 50 is returned to the bore 56 through a channel 92.

Slidable within the bore 56 are

actuator pistons

94 and 96 with these two pistons arranged in tandem such that the piston 94 operates independently of the piston 96. However, operation of the latter imparts motion to the former. A spring 98 is positioned within the bore 56 between one end thereof and the innerface of the piston 94. The spring 98 biases both the

pistons

94 and 96 to the left with the farthermost travel in that direction controlled by a stop 100 extending from the face of the piston 96.

Circumferentially arranged about the skirt 102 of the piston 94 are openings 104 to permit a fluid to flow into the skirt portion of the piston. Similarly, openings 106 are circumferentially arranged about the skirt 108 of the piston 96. The open end of the skirt 108 allows a fluid pressure within the bore 56 by means of the openings 106 to apply an exerting rightward directed force on the piston 94. Each of the

pistons

94 and 96 is provided with an O-ring seal 110 thus enabling the buildup of a pressure differential across each of the pistons.

Turning now to the operation of the hydraulic system of FIG. 1 and in particular the novel valve arrangement 10, a mechanical input signal applied to the connector 20 displaces the valve member 58 to the left an amount in excess of the overlap of the land 60 of the passage 38 thus opening the passage 38 to the passage 52 allowing fluid pressure from the pump 6 to be directed into the bore 56. Also, the land 66 is displaced by an amount to completely overlap the passage 43. At this time, the land 64 moves farther to the left away from the passage 42 and the area of the bore 56 communicating with the passage 54 is open to the reservoir 30.

Movement of the valve member 58 to the left also displaces the land 62 an amount in excess of the overlap of the passage 40 thereby allowing fluid pressure from the pump 16 into the passage 48. However, the land 76 is in the position illustrated in FIG. 2 to close off the passage 48 and fluid is blocked at this point. The land 68 remains in a position to close off the passage 45 thereby blocking the reservoir 30 from the passage 40. Movement of the land 66 to the left uncovers the passage 44 thereby establishing a flow path from the passage 46 to the reservoir 30.

With the valve member 58 in the position as described, fluid from the pump 16 passes through a timing orifice 112 in the passage 38 through the bore 34 into the passagee 52 and then into the bore 56 in the area between the

pistons

94 and 96. Assuming a constant pressure source, the amount of fluid passing through the timing orifice 112 establishes the rate at which a pressure will be developed on the piston 94 to exert a rightward directed force. As a fluid pressure builds up in the bore 56 on the piston 94 the force developed acts against the spring 98 causing the piston to be displaced toward the trigger 88. A continued buildup of pressure moves the piston 94 in contact with the trigger 88 which is then stroked to move the secondary slider valve member 70 to the right opening the

passages

46 and 48 by movement of the

lands

74 and 76 to the right against the force of the spring 84. This condition is illustrated in FIG. 3 where the valve member 70 is in a far right position.

With the blocking valve open, the flow rate through the outlet passage 86 to the actuator 12 is proportional to the displacement of the valve member 58. Fluid discharged from the actuator 12 by operation thereof is returned to the reservoir 30 through the

passages

78, 46, and 44 through the channel 28.

Now if the valve member 58 is returned to its neutral position where the land 60 closes off the passage 38 then the land 66 will move to a position such that the passage 43 will be open to the bore 34. This opens the bore 56 in the area between the

pistons

94 and 96 to the reservoir 30 through the passage 52. Pressure within the bore 56 at the piston 94 begins to decrease and the spring 98 exerts a force on the piston for movement thereof to its far left position. The spring 98, acting on the piston 94, thus forces the fluid from the bore 56 through the

passages

43 and 52 to the reservoir 30. At the same time, the spring 84, acting on the collar 82, forces the valve member 70 to its far left position thereby closing the

passages

46 and 48 with the

lands

74 and 76, respectively. The above action occurs very quickly as there are no restrictions in the

passages

43 and 52 to the reservoir 30.

Consider next a movement of the valve member 58 toward the right whereby the land 64 closes the passage 42 and the land 60 opens the passage 38 to establish a fluid path to the passage 54. A movement of the valve member 58 to the right will cause the land 66 to continue to close off the passage 44, but now the passage 40 is opened to establish a fluid path to the passage 46. Movement of the land 68 to the right opens the passage 45 to the passage 48. Fluid entering the passage 46, however, is blocked at the land 74 and the flow path to the

passages

45 and 48 is blocked at the land 76. This has been described previously.

Fluid passing through the timing orifice 112 now enters the bore 56 at the head of the piston 96 establishing a force directed to the right against the piston 94. This force is transferred to the piston 94 which also moves to the right against the bias of the spring 98. After a predetermined time, as determined by the timing orifice 112, fluid pressure within the bore 56 builds up to a level such that the piston 94 actuates the trigger 88 to move the valve member 70 to the right against the force of the spring 84. A flow path is established between the passage 46 and the outlet passage 78 to the actuator 12 and fluid discharged from the actuator 12 flows through the

passages

86, 48 and 45 to the reservoir 30.

A return of the valve member 58 to its center position again closes off the

passages

38 and 40 and establishes a flow path from the bore 56 through the

passages

54 and 42 to the reservoir 30. The timing mechanism strokes to the left to be reset for a subsequent cycle. Thus, whichever direction the valve member 58 is stroked it produces the same result at the

outlet passages

78 and 86. Should the valve member 58 be displaced from its center position for a period of time less than that required to stroke the

pistons

94 and 96 to actuate the blocking valve, both of these pistons will immediately return to the far left position until a new time cycle is started.

Assuming a constant pressure supply from the source 16, and that the passage 38 opens fully upon a movement of the valve member 58 to either the left or right, and also assuming that the forces produced by the

springs

84 and 98 are not excessive, the time delay for the system in seconds is given by the equation:

: SEC.

sec.

Thus, the time delay may be varied in sizing the timing orifice 112 to produce either a longer time delay before actuating the secondary valve member 70 or a shorter time delay depending on the desired response at the actuator 12.

Referring to FIG. 4, there is shown an embodiment of the invention where the timing mechanism is separate from the main control valve thus enabling use of the timing mechanism with various designs of control valves. Many prior art time delay mechanisms out of necessity incorporated the time delay structure as an integral part of the operating valve and thus could only be employed with the specific incorporated operating valve structure. This provides a definite disadvantage because in order to get a time delay function in a fluid system, it is necessary to utilize a certain often undesired attached operating valve. With the embodiment of FIG. 4 the invention provides an additional advantage of providing a time delay mechanism adaptable to be used in any fluid system. with various designs of operatingvalves.

As illustrated, the operating valve comprises a housing 114 having a bore 116 in which is operated the valve member 58 with the

lands

60, 62, 64, 66 and 68 as described in FIG. 2. Within the housing 114 are

inlet passages

38 and 40 and discharge passages 42-45. Note, that in the embodiment of FIG. 4 the passage 38 does not include the timing orifice 112. Also communicating with the bore 116 are

passages

46, 48, 52 and 54 as described previously. Operationally, the main control valve of FIG. 4 is identical to that of the embodiment of FIG. 2.

Coupled to the housing 114 of the main control valve is a timing mechanism including a housing 118 having bores and 56 interconnected by means of a channel 90. As illustrated, the timing mechanism of FIG. 4 is similar to that of FIG. 2 with the slider member biased by means ofa spring 84 and including

lands

72, 74 and 76. In contact with the land 72 is the trigger 88 extending into the bore 56 within the skirt area of the piston 94. In tandem with the piston 94 is the piston 96 1 both being biased to the left by means of the spring 98.

Communicating with the bore 50 are outlet passages 78 and and also

passages

46 and 48. Communicating with the bore 56 are passages 52' and 54.

Coupling the passages 48 and 48' is a conduit 120 and coupling the passages 46 and 48' is a conduit 122. These conduits complete the flow path from the source 16 to the actuator 12. Coupling the passage 52 to the passage 52 is a conduit 124 with a timing orifice 126 forming a flow restriction from the bore 116 to the bore 56. Coupling the passage 54 to the passage 54is a conduit 128 with a timing orifice 130 forming a flow restriction to establish a desired time delay.

In operation of the embodiment of FIG. 4, movement of the valve member 58 to the left establishes a flow path from the passage 38, the passage 52, the conduit timing mechanism through the timing orifice 130. Again, the timing orifice establishes the time delay which may be the same as established by the timing orifice 126 or may be varied to be either faster or slower. Thus, with the embodiment of FIG. 4, the time delay for coupling fluid pressure to the actuator may be different or the same depending on the size of the timing orifices 126 and 130. This provides additional versatility to the timing mechanism.

As a modification of the embodiment of FIG. 4, the conduits 124 and 128 are coupled into the

conduits

120 and 122, respectively, and the control valve utilizes only the

lands

62, 66 and 68. In this modification, a movement of the slider member 58 to the left establishes a flow path from the passage 40, the passage 48,

conduits

120 and 124 and passage 52 through the timing orifice 126 to the timing mechanism. A movement of the slider member 58 to the right establishes a flow path from the passage 40, the passage 46, conduits 122 and 128 and passage 54' to the timing mechanism through the timing orifice 130. Operationally, this modification of the embodiment of FIG. 4 is the same as described. This modification further emphasizes the versatility of the separate timing mechanisms independent of the control valve.

While several embodiments of the invention, together with modifications thereof, have been described in detail herein and shown in the accompanying drawings, it will be evident that various further modifications are possible without departing from the scope of the invention.

What is claimed is:

l. A time delay mechanism for controlling a fluid flow in a fluid control system, comprising in combination:

a secondary slider valve movable between an open position and a closed position for controlling a fluid flow from input lines to output lines as part of the control system;

a trigger coupled to said secondary slider valve for moving the valve from the closed position to the open position;

an actuator responsive to a fluid pressure for activating said trigger to move said slider valve;

a selectively operable primary slider valve for controlling a fluid flow to the input lines of the secondary slider valve from a fluid source and also for controlling a fluid flow to said actuator from the fluid source; and

means defining an orifice in a line from the source to the actuator to establish a time delay between the movement of the primary slider valve and the movement of the secondary slider valve, said actuator further comprising first and second distinct piston means, said first piston means being independently movable with respect to said second piston means, said first piston means being movable to activate said trigger in response to said fluid pressure when said primary slider valve moves in a first direction, said second piston means being movable to effect the activation of said trigger in response to said fluid pressure when said primary slider valve moves in a second direction.

2. A time delay mechanism as set forth in claim 1 including means for returning said secondary slider valve to the closed position when said primary slider valve closes the line from the source to said actuator.

3. A time delay mechanism as set forth in claim 2 including a spring to return said first and second piston means to a home position when said primary slider valve closes the line from the source.

4. A time delay mechanism for controlling a fluid flow in a fluid control system, comprising in combination:

a secondary slider valve movable between an open position and a closed position for controlling a fluid flow from input lines to output lines as part of the fluid control system;

actuator means responsive to a fluid pressure for activating said slider valve to move from the closed position to the open position;

a selectively operable primary slider valve for controlling a fluid flow to the input lines of the secondary slider valve from a fluid source and also for controlling a fluid flow to said actuator means from the fluid source; and

means defining an orifice in a line from the source to said actuator means to establish a time delay between the movement of the primary slider valve and the movement of the secondary slider valve, said actuator means further comprising first and second piston means, said first piston means being independently movable with respect to said second distinct piston means, said first piston means being movable to open said secondary slider valve in re sponse to said fluid pressure when said primary slider valve moves in a first direction, said second piston means being movable to open said secondary slider valve in response to said fluid pressure when said primary slider valve moves in a second direction.

5. A time delay mechanism as set forth in claim 4 including means for returning said secondary slider valve to the closed position when said primary slider valve closes the line from the source.

6. A time delay mechanism as set forth in claim 5 wherein said means for returning comprises a spring biased to move the secondary slider valve into a closed position.

7. A time delay mechanism for controlling a fluid flow in a fluid control system, comprising in combination:

a housing having a first bore therein axially aligned and in communication with a second bore in the housing, said housing further including a third bore with fluid passages to the first and second bore and additional fluid passages to a fluid source;

a secondary slider valve in said first bore movable between an open position and a closed position for controlling a fluid flow from passages in said housing to output lines as part of the fluid control systern;

a trigger slidable in a channel between the first and second bores and coupled to said secondary slider valve for moving the secondary valve from the closed position to the open position;

an actuator in the second bore of said housing and responsive to a fluid pressure in passages from the third bore for activating said trigger to move said slider valve;

a selectively operable primary slider valve in the third bore for controlling a fluid flow to the passages to the first bore from the fluid source and also for controlling the fluid flow to passages connected to the second bore from the fluid source; and

means defining an orifice in a line from the source to said actuator to establish a time delay between the movement of the primary slider valve and the movement of the secondary slider valve, said actuator further comprising first and second distinct piston means, said first piston means being independently movable with respect to said second piston means, said first piston means being movable to activate said trigger in response to said fluid pressure when said primary slider valve moves in a first direction, said second piston means being movable to effect the activation of said trigger in response to said fluid pressure when said primary slider valve moves in a second direction.

8. A time delay mechanism as set forth in claim 7 wherein the second bore comprises a cylinder including a spring to return said first and second piston means to a home position when said primary slider valve closes the line from the source.

9. A time delay mechanism as set forth in claim 8 including a spring in the first bore for returning the secondary slider valve to the closed position when said primary slider valve closes the passages to the first bore from the source.

Claims

1. A time delay mechanism for controlling a fluid flow in a fluid control system, comprising in combination: a secondary slider valve movable betWeen an open position and a closed position for controlling a fluid flow from input lines to output lines as part of the control system; a trigger coupled to said secondary slider valve for moving the valve from the closed position to the open position; an actuator responsive to a fluid pressure for activating said trigger to move said slider valve; a selectively operable primary slider valve for controlling a fluid flow to the input lines of the secondary slider valve from a fluid source and also for controlling a fluid flow to said actuator from the fluid source; and means defining an orifice in a line from the source to the actuator to establish a time delay between the movement of the primary slider valve and the movement of the secondary slider valve, said actuator further comprising first and second distinct piston means, said first piston means being independently movable with respect to said second piston means, said first piston means being movable to activate said trigger in response to said fluid pressure when said primary slider valve moves in a first direction, said second piston means being movable to effect the activation of said trigger in response to said fluid pressure when said primary slider valve moves in a second direction.

4. A time delay mechanism for controlling a fluid flow in a fluid control system, comprising in combination: a secondary slider valve movable between an open position and a closed position for controlling a fluid flow from input lines to output lines as part of the fluid control system; actuator means responsive to a fluid pressure for activating said slider valve to move from the closed position to the open position; a selectively operable primary slider valve for controlling a fluid flow to the input lines of the secondary slider valve from a fluid source and also for controlling a fluid flow to said actuator means from the fluid source; and means defining an orifice in a line from the source to said actuator means to establish a time delay between the movement of the primary slider valve and the movement of the secondary slider valve, said actuator means further comprising first and second piston means, said first piston means being independently movable with respect to said second distinct piston means, said first piston means being movable to open said secondary slider valve in response to said fluid pressure when said primary slider valve moves in a first direction, said second piston means being movable to open said secondary slider valve in response to said fluid pressure when said primary slider valve moves in a second direction.

7. A time delay mechanism for controlling a fluid flow in a fluid control system, comprising in combination: a housing having a first bore therein axially aligned and in communication with a second bore in the housing, said housing further including a third bore with fluid passages to the first and second bore and additional fluid passages to a fluid source; a secondary slider valve in said first bore movable between an open position and a closed position for controlling a fluid flow from passages in said housing to output lines as part of the fluid control system; a trigger slidable in a channel between the first and second bores and coupled to said secondary slider valve for moving the secondary valve from the closed position to the open position; an actuator in the second bore of said housing and responsive to a fluid pressure in passages from the third bore for activating said trigger to move said slider valve; a selectively operable primary slider valve in the third bore for controlling a fluid flow to the passages to the first bore from the fluid source and also for controlling the fluid flow to passages connected to the second bore from the fluid source; and means defining an orifice in a line from the source to said actuator to establish a time delay between the movement of the primary slider valve and the movement of the secondary slider valve, said actuator further comprising first and second distinct piston means, said first piston means being independently movable with respect to said second piston means, said first piston means being movable to activate said trigger in response to said fluid pressure when said primary slider valve moves in a first direction, said second piston means being movable to effect the activation of said trigger in response to said fluid pressure when said primary slider valve moves in a second direction.