US2825770A - Time delay control device - Google Patents

Description

' March 1958 R. G. HELSPER 2,825,770

TIME DELAY CONTROL DEVICE Filed Aug. 20, 1954 H INVENTOR I R0 erf 8 7 limited States Patent TIME DELAY CONTROL DEVICE Robert G. Helsper, Paramus, N. J., assignor to Specialties Development Corporation, Belleville, N. J., a corporation of New Jersey Application August 20, 1954, Serial No. 451,212

1 Claim. (Cl. 200-33) This invention relates to control devices, and, more particularly, to such devices which, upon operation, effect the actuation of apparatus after the lapse of a predetermined period of time.

When an airplane is involved in a collision, either in the air or in crashing to the ground, one of the greatest dangers is that its fuel and oil storage tanks and lines are broken and that the contents thereof are spilled and ignited and/or fuel vapors are caused to explode. Consequently, it has been proposed to fight such fires by installing fire extinguishing systems and fuel and oil shutoff valves controlled by a device responsive to collision or crash.

Generally, such systems and valves are operated by electrically actuated means which increase the fire hazard because of possible overheating or arcing of broken or short circuited electrical conductors in a crash.

Accordingly, an object of the present invention is to provide a time delay control device which, when operated after a crash has occurred, first allows a short but sufiicient lapse of time to assure electrical energization of the fire extinguishing system and valve operating devices or the like, and then effects the actuation of means for completely deenergizing the electrical circuits before combustible vapors or liquids can be ignited or exploded by sparks or hot wires within the electrical circuits.

Another object is to provide such a device in which the time delay may be accurately adjusted for various desired delays.

Another object is to provide such a device which may be manually reset.

Another object is to provide such a simple and practical device which is compact and light in weight, is readily assembled and serviced, and is reliable in operation.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the invention, the foregoing objects are generally accomplished by providing a time delay control device comprising a generally circular cam having a surface for normally maintaining a controlled element inactive and formed with a contour for effecting actuation of the controlled element and having a stop thereon, means for rotatably mounting the earn, a spring for effecting rotation of the cam, means for engaging the stop to normally prevent rotation of the cam, and means for moving the last mentioned means out of engagement with the stop, whereby the cam is rotatable and the contour thereon is moved into position for effecting actuation of the controlled element.

In order to vary the time delay, means are provided for adjusting the tension on the spring so that the speed of rotation of the cam may be controlled. Means are also laterally from the cam side wall and has its other end 2,825,770 l atented Mar. 4, 1958 2 provided for resetting the apparatus after operation thereof.

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

Fig. l is a plan view of apparatus in accordance with the invention, with the cover removed and a portion of the cam and resetting mechanism mounting means broken away;

Fig. 2 is a sectional view taken substantially along the lines 2-2 of Fig. 1; and

Fig. 3 is a sectional view taken substantially along lines 3-3 of Fig. 1.

Referring to the drawing in detail, and more particularly to Fig. 1 thereof, there is shown a time delay control device comprising a casing or frame 10 having a conventional electrical connector 11 at one side thereof, a time delay mechanism 12 centrally located within the casing, a solenoid controlled mechanism 14 within the casing adjacent the connector for rendering the time delay mechanism effective, and an electric switch 15 adjacent the end of the casing opposite the connector which is adapted to be actuated by the time delay mechanism. Although not shown, the terminals of the solenoid controlling the mechanism 14 and the terminals of the switch are electrically connected to the connector in the usual manner.

The time delay mechanism 12 consists of a generally circular cam 16, a torsion spring 17 for rotating the cam in a counterclockwise direction, as viewed, and an adjustable member 19 for varying the spring load tending to rotate the cam.

As shown herein, the cam is formed with a concentric bore 20 extending therethrough, and a generally circular cam surface 22 provided with a fiat zone or dwell 24 and with a recess 25 substantially diametrically opposite to the dwell. The cam is mounted for rotation with a stepped shaft 26 having a shoulder 27 against which the end wall of the cam abuts, and the shaft is journalled for rotation in suitable bearings, one of which is mounted in the back wall of the casing and the other of which is mounted in a shaft guide plate 29 secured to the casing at the front thereof.

The spring 17 is a helical torsion spring which is coiled about the shaft 26 between the cam and the casing back wall and has one end connected to a pin 30 projecting the connected to adjustable member 19. As shown in Fig. l, and as indicated by the arrow on the cam, the spring 17 is so arranged as to rotate the cam in a counterclockwise direction.

The adjustable member 19 has an arcuate slot 31 and is secured on a boss 32 provided on the casing, by the head of a screw 34 having a shank passing through the slot and threaded into the boss. A pair of tabs 35 are formed on the member 19, one at each end thereof, and each having an aperture for connecting the spring 17.

The solenoid controlled mechanism 14 includes an arm 36 having one end pivotally mounted on a boss 37 projecting from the casing back wall (Figs. 2 and 3) and having a transversely extending finger 39 at the other end thereof adapted to engage the recess 25 in the cam 16.

The solenoid for controlling the mechanism 14 may be of conventional design and is mounted in a supporting bracket 40 in the casing adjacent the mechanism 14. The core of the solenoid is pivotally connected to the mechanism at its free end to move the same in a direction to withdraw the finger 39 from the recess 25.

The switch 15 may be a conventional micro switch having the usual terminals, an operating plunger 41 and a roller 42 mountedadjacent the end of the plunger 3 on a flexible lever 44 secured to the switch body. flhe "switch is so disposed in the casing that the roller is urged by the lever 44 into abutting relation with the cam surface 22 of the earn 1 6 adjacent the dwell 24 in a clockwise direction therefrom as viewed in Fig.1. I

In order to enable the time delay mechanism to be reset after operation, resetting means are provided ineluding a gear 45 mounted on the shaft 26 for rotation therewith, a gear segment 46 having a greater radius than the gear 45 and mounted on a shaft 47 for rotation therewith and meshing with the gear 45. The shaft 47 is parallel to the shaft 26 and is journalled for rotation in bearings respectively mounted in the shaft guide plate 29 and in the casing back wall. A manually engageable lever 48 is integrally connected to the shaft s7 and extends out of the casing through a slot 49 formed therein. 7 I

In operation, the solenoid is energized to draw the co'r'e thereof in a direction away from the cam whereby the arm 36 is rocked to cause the finger 39 to disengage the recess 25. When such disengagement is effected, the cam 1.6, and the shaft 26 rotate in a counterclockwise direction as viewed in Fig. 1, under the influence of the spring 17, whereupon, after a predetermined lapse of time, the dwell 24 is positioned adjacent the roller 42. As the cam rotates, the lever 44 urges the roller in a direction to maintain contact with the cam surface so that, when the dwell 24 opposes the roller, the lever 44 moves the roller in a direction away from the switch 15 permitting the plunger 41 to move towards the cam and to operate the switch.

in order to adjust the lapse of time between energi; 'zation of the solenoid and actuation of the switch, the screw 34 is loosened and the adjustable member 19 is moved to the desired position; to the left, as viewed in Fig. l to increase the tension on the spring 17 and thus decrease the lapse of time, or to the right to decrease the spring tension and increase the time delay. By providing a tab 35 at each end of the member 19 for connecting the spring, adjustment of the spring tension over a range substantially twice the annular length of the member 19 is made possible.

During rotation of the cam '16 and the shaft 26, the gear 45, mounted on the same shaft, also rotates causing the gear segment 46, and consequently the shaft 47 and the lever 43, to rotate about the longitudinal axis of the shaft 47. Upon actuation of the switch 15, the lever 43 is therefore in a position to indicate the operated condition of the apparatus.

To reset the switch and its control device, the lever 48 is manually returned 'to its normal position, wherefore, the gear segment rotates the gear and the cam in a clockwise direction, as viewed in Fig. 1, against the action of the spring 17, until the recess 25 is opposite the finger 39, at which time the solenoid spring (not shown) urges the core in a direction to effect engagement of the finger and the recess, thus returning the elements to their normal position, since movement of the dwell 24 away from the roller 42 effects depression of the plunger 41. v

In order to prevent the dwell from travelling past the roller before the circuit controlled by the switch has an opportunity to be deenergized, a stop may be provided consisting of a generally U-shaped spring 56' mounted on a raised portion '51 of the casing. One leg of such a spring is shorter than the other and is folded back upon itself so that the pin 30 will depress and pass the short leg, strike the long leg and be retained therebetween when the roller abuts the center of the dwell.

As shown in Fig. 2, the roller 42 is offset with respect to the recess '25 to prevent the roller from being disturbed thereby and causing premature movement of the plunger. I

From the "foregoing description, it "will be seen that the present invention provides a compact, reliable and lightweight control device which, upon energization, permits the lapse of a predetermined period of time before effecting deenergization of an electrical circuit. It will also be seen that the time delay may be varied within a wide range and that the device may be readily reset. The casing may be provided with a suitable cover and gasket (not shown) to render the same moisture proof and an O-ring may be disposed around the shaft 47 between its bearing in the casing and the lever 48 for the same purpose.

While the invention has been described in connection with a system wherein it is used to open a circuit, it will be understood that it may readily be adapted for use with applications requiring a time delay to close rather than to open circuits.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

Iclaim:

A time delay control device comprising a frame having a base formed with an elongate slot providing a stop at eachend thereof, a shaft rotatably mounted on said frame and spaced upwardly from and extending crosswise with respect to said slot, a controlled device mounted on said frame at one side of said shaft and spaced there from having an element facing said shaft, a cam mounted on said shaft for rotation therewith having a generally circular surface for normally maintaining said element in agiven position and having a second surface of much shorter circumferential extent than said first mentioned surface for effecting movement of said element to another position and having a cavity in said first mentioned sur face substantially diametrically opposite said second surface which is positioned to travel in a path to one side of said element, a spring associated with said cam for efl'ecting rotation thereof in a single direction and adapted to yield to permit resetting of said cam, an arm pivotally mounted on said frame at the other side of said shaft having a finger extending into said cavity to lock said cam in a set position, normal inactive means linked to said arm for effecting movement of said arm to withdraw said finger from said cavity and release said cam for rotation under the influence of said spring, a gear secured to said shaft above said slot, and a reset lever mounted for pivotal movement about an axis parallel to the axis-about which said shaft rotates and located intermediate said shaft and said slot, said lever having an upp'er arm formed with a gear segment meshing with sa d gear and having a lower arm extending through said slot and adapted to engage the stops thereof, said slot, said cam surfaces, said element, said finger, said gear and reset lever being constructed and arranged so that before said lower arm engages one of said stops said finger enters said cavity and when said lower arm engages the other of said stops said element engages said second cam surf'ace.

References Cited in the file of this patent UNITED STATES PATENTS 2,056,193 Hubbell Oct. 6, 1936 2,112,422 McCullough et al Mar. 29, 1938 2,149,542 Peltz Mar. 7, 1939 2,162,442 Miller June 13, 1939 2,202,297 Mudon May 28, 1940 2,602,865 Maurer July 8, 1952 2,614,187 Dorothea Oct. 14, 1952 2,657,743 Aubert Nov. 3, 1953 Clubbet a1 Apr. 6, 1954 "2,677,029 Van Valkenbur'gh Apr. 27, 1954 2,690,526 "Morrison Sept. '28, 19 54

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