US3110780A - Safety switch - Google Patents

Description

United States Patent This invention relates to switches and more particularly to'safety switches rendered inoperable by gravitational force, inertia or momentum.

The users of motorized vehicles constantly indicate a desire for an increase in electrical equipment in acquiring new vehicles. As an example, electric fuel pumps have come into wider use. This particular use poses a prob-lem-i.e., in the event of vehicle collision or upset an electric fuel pump must not continue pumping gasoline. Whether it be a fuel pump or some other electrical accessory being operated, it is clear that the circuit supplying that accessory should be opened auto matically in the event of a sudden stop as occasioned by a collision or the overturning of a vehicle and that circuit should not be closed again until the operator desires operation of that accessory or takes a deliberate step to that end. Mere righting of an upset vehicle should not close the circuit.

An object of the present invention is to provide an improved safety relay switch which is simple and low in cost and which will automatically serve to open an electric circuit when sudden force is applied because of vehicle upset or collision necessitating resetting of the switch before the circuit can be closed again.

A feature of the present invention is a single pole switch having two contacts normally in a path of alignment and adapted to complete a circuit and subject to abnormal misalignment by force until deliberately reset. Another feature is a switch having two contacts adapted to close a circuit with one of the contacts being pendulum mounted and subject to movement to break contact and alignment with respect to the other, means being provided to restrain the contacts from closing the circuit until alignment of the contacts is deliberately effected.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claim.

In the drawings:

FIGURE 1 depicts a switch as one embodiment of the present invention utilized with an electrical circuit for a fuel pump on an automobile, the circuit being shown diagrammatically and the switch being of the normally open type; and

FIGURE 2 is another embodiment of a safety switch similar to that shown in FIGURE 1 but which is of the normally closed type.

The fuel pump circuit as depicted in FIGURE 1 is more fully described in the United States patent application Serial No. 4,440, filed January 25, 1960, now Patent No. 2,989,644, in the name of Werner F. Schultz, and entitled Safety Systems for Electric Fuel Pumps. Details regarding the circuit are not given here as the circuit forms no part of the present invention but a casual inspection of the circuit will show that operation of the fuel pump 12 is by current derived from a battery 10 when the ignition switch 13 is closed. The circuit to the pump to cause the latters operation is also through two contacts 14 and 16. When these contacts are normally open, the fuel pump must stop. The circuit is such that during running of the engine, the power supply for the pump 12 is taken from the generator or the battery depending on speed and during starting, from the battery, the shift from one to the other being auto matic.

3 ,1 10,78h Patented Nov. 12, 1963 The safety switch of FIGURE 1 comprises an L-shaped bracket 29 which serves as a support for the contacts 14 and 16 as well as a solenoid generally indicated at 2'2 and having a coil 24. Whenever the coil 24 of the solenoid is energized, a condition necessary for operation of the pump 12, the core 26 of the solenoid attracts an armature 28, closing contacts 14 and 16. This armature is a flat piece fixed to a spring arm 30. One end of the latter is riveted, as at 32, to the support bracket 20. The spring arm 34 is such that a free end thereof will be in the normally open position depicted at 31 in dot-and-dash lines in FIGURE 1 when the coil 24 is not energized. This free end carries the cylindrical contact 14. A horizontal leg 34 of the support bracket 20 is apertured to receive a hub- 36 which is integral with a dielectric circular spring end retaining plate 38. Loosely suspended within the hub 36 to aid in forming a pendulum mounting for the contact 16 is a shaft 40'. This shaft carries weights 42 and 44 at opposite ends. The weight 42 has a shoulder portion 46 on its underside which rests on the hub 36. The upper surface of the weight 44 bears a reduced diameter shoulder portion 50. A coil spring 52 surrounds the rod 40 and one end rests on the underside of the plate 38 and the other end snugly fits around the portion 50. The spring 52 is under compression tending to hold the rod 40 in a vertical position so that the contacts 14 and 16 are normally in a path of alignment. The spring action of the arm 30 is adapted to guide and urge the contact 14 along the alignment path as will further appear. The pendulum mounting of the contact 16 on the other hand permits movement of the contact 16 in the second or lateral path substantially transverse to the alignment path.

Surrounding the contact 16 and fixed thereto is a collar 54 of insulating material. This collar extends downwardly but to such an extent as not to interfere substantially with the lateral movement of the contact 16 with respect to the contact 14 as will further appear.

In starting the engine, the ignition switch 13 must first be closed. Subsequent closure of the starter switch 15 not only cranks the engine but energizes the relay coil 24 to close the contacts 14 and 16. The pump then operates at battery voltage. When the engine runs, there is a reversal in the current in the coil 24 as the generator becomes effective. Grounding of the coil 24 is either through the generator or the starter.

In the operation of the arrangement of FIGURE 1, the energizing of the coil 24 of the solenoid 22 is accompanied by the operation of the fuel pump 12 as heretofore stated. At this time, the contacts 14 and 16 are operationally closed as positioned in full lines in the figure. Assuming, however, that the vehicle being served by the fuel pump is either upset or involved in a collision, the mass involved in the two weights 42 and 44 will cause the contact 16 to move laterally or transverse to the path of contact alignment and into a position such as depicted in dot-and-dash lines. This will separate the contacts 14 and 16 and stop the fuel pump 12 and the circuit for the pump cannot be closed again until done so deliberately whether the coil 24 be energized or not. This is because the free end of the spring arm 30 will first move upwardly to its top position. At this stage of the operation, the position of the free end of the arm 30 will be as depicted by the do=t-and-dash lines at 60. The contact '16 cannot swing back into the path of alignment with the contact 14 as the insulation collar 54 will separate the two contacts. Ordinarily, however, if the contact 16 has swung out of alignment with the contact 14 and the contacts are separated, the coil 24 becomes deenergized with the stoppage of the engine and the spring arm 30 will be released to its pendulum mounting as in 'FIGURE 1.

' separating the contacts.

In the switch arrangement of FIGURE 2, a supporting bracket Zii is employed to support the contact 16 with a An insulating collar 72, which is similar to the collar 54, is employed in this particular embodiment out it is mounted surrounding the lower contact 14. The collar extends upwardly an adequate distance to insure no meeting of the two contacts when they are out of the path of alignment but does not extend sufficiently to interfere with lateral movement .of the contact 16 necessary for breaking the circuit. A solenoid 74 utilizing a coil 76 is supported by means not shown but in this instance is located below a spring arm 78 to aifect the position of an armature 8%) attached midway the length of the spring arm. The switch is shown with the contacts 14 and 16 in solid lines in their aligned and'ope-ratively open positions during which the coil 76 is energized. The normally closed position of the contact 1 4 is effected by 'virtue of spring action by the spring arm '78 when the contact 16 is. in the alignment path and the coil 76 is deenergized. When impact or upset of the vehicle occurs, the contact 16 swings out, the spring arm 78 moves upwardly into the dot-and-dash 'line position of FIGURE 2 and the insulator collar 72 prevents reestablishment of a circuit. Before the normally closed and aligned positions of the contacts may be as sumed again, coil '76 must be momentarily energized to pull the spring arm 78 downwardly and permit the realignment of the contacts by action of the spring 52 and the weights 4'2 and 44. With the deliberate energizing and subsequent deenergizing of the coil '76, the normally closed positions of the contacts wvill be had.

In each figure of the drawing the collar '54 or 72 is preferably annular so that it becomes immaterial in which horizontal direction the contact 16 may be caused to swing.

. We claim:

A switch having two contacts normally in a path of alignment, a first of said contacts being movable sub-stantia lly along said alignment path, the other of said contacts being movable in a second path substantially transverse.

to said alignment path, insulating means on. one of said contacts to prevent their contact subsequent to their move ments in said paths toward the intersection thereof, and solenoid actuated means associated with said first contact for moving the :latter along said alignment path toward and away from said intersection whereby normal alignment of said contacts may be established.

References Cited in the file of this patent UNITED STATES PATENTS 2,013,924 Noite Sept. 10, 1935 2,236,872 Grigsby Apr. 1, 1941 2,415,086 Detwiler Feb. .4, 1947 2,475,728 Smith July 12, 1949 2,596,427 Norclrnark et a1. May 13, 1952 2,778,896 Toilet-sen Jan-22, 1957 2,783,321 Richardson Feb. 26, 1957 FOREIGN PATENTS 554,282 Germany June 16, 1932

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