US1744930A - Electrical switch - Google Patents

Description

Jan. 28, 1930. M. c. SPENCER ELECTRICAL SWITCH Filed Oct. 26. '1926 Z'Sheets-Sheet 1 Inv enter, Millard Cole Spencer,

AHorney.

Jan. 28, 1930. r M. c. SPENCER 1,744,930

ELECTRICAL SWITCH Filed Oct. 26. 1926 2 Sheets-Shegt 2 Invent r,

Mmard Cole Sp enc er.

Attol" Hey Patented Jan. 28, 1930 UNITED. STATES PATENT OFFICE MILL-m1) COLE srnncnn, or msrr camera, rmw JERSEY, ASSIGNOR 'ro cnocxnn- WHEELER ELECTRIC mnoreoruame-comrnmr, or AMPERE, NEW JERSEY, A

CORPORATION OF NEW JERSEY uncommon. SWITCH Application filed October 26, 1926. Serial No. 144,246. I

In the operation of gas-electric, vehicles, an engine drives an electric generator, and the generator supplies current to the motor which propels the vehicle. Control of speed may be Wholly through the control of gas to the engine and the brakes, provided that there are suitable automatic means for preventing excessive current flow from the generator to the motor. I

The object of this invention is to provide such automatic means in the form of a solenoid operated switch suitable for operation by the current flowing from the generator to the motor, and for controlling the shunt field of 1 the generator. Further objects are to provide a switch which is sensitive and reliable in its automatic action and which will be brought to a definite position by a definite flow of the operating. current regardless of whether the definite flow has followed a greater or a lesser flow. A- further object is to provide a regulating system which will be smooth. in its action so that excessive surges of current will be avoided and acceleration without undue shock will be insured. A further object is to provide a switch the operation of which will not be influenced by the jolting or other abrupt movements of the vehicle.

ings which form a part of this description,

Figure 1 is a plan view of a switch which embodies this invention, the'top cross bar being broken away. I

Fig. 2 is an elevation of the same.

Fig. 3 is a section through the comb of contact fingers and the support therefor.

Fig. 4 is a diagram of the circuits.

The switch comprises a frame 10 which carries a shaft 11. Two solenoid coils 12, 12 are supported by the frame. They are disposedalong arcs of a circle and on opposite sides of the circle. Armature cores 13, 13 in balanced relation are carried by arms 14, 14 from the shaft. On the shaft are a series of coiled springs 15, 15 which are preferably quite limber and held nearly wound up and therefor under initial tension by a bar 16 which is carried by the shaft. Throughout 50 the operative movement of each spring its In the accompanying two sheets of drawtension remains substantially uniform. A support 17 of insulating material carries a comb of spring fingers 18, 18 which rest on contact buttons 19, 19. A bar 20 limits the lift of the fingers away from the contact buttons. The support for the comb of spring fingers and the contact buttons is set at an angle to the axis of the shaft, so that as the shaft turns the ends of coiled springs carried by the shaft will engageand lift the contact fingers successively. The initial tension of the coiled springs is greater than that of the contact fingers. In consequence, each finger on being engaged, if there is sufii cient force to lift it, will be at once fully lifted against the limiting bar and not left in hesitating contact. During any further movement of the shaft in the same direction after the contact finger has been lifted, the end of the coiled spring remains in engagement with the tip of the contact finger and alone yields.

Leads 21, 21 connect the comb of contact fingers and the contact buttons with blocks of resistances 22, 22 in series with the shunt field 23 of the generator. Current is led from the armature 24 of the generator through the solenoid coils of the switch and thence to the vehicle motor 25.

In operation, with'the engine turning over slowly substantially no voltage will be generated and the vehicle will be held if necessary by its brakes when a temporary stop is bein made. To start up, the brakes are release and the engine is speeded up. Current is at once generated and the generator field strongly excited. To prevent the current from reaching an excessive value before the vehicle has had time to get underway and its motor has had suficient time to build up a 90 sufiicient counter electromotive force is the purpose of the switch. This is effected by the flow through the actuating solenoids which causes the locks of resistance to be inserted in series in the generator field circuit, thereby weakening the field and keeping the current generated down to a proper value. As the vehicle speeds up and the counter electromotive force of the motor increases the current tends to decrease. This decrease in 100 current through the solenoid coils of the switch 'cuts out resistance in the field circuit of the generator thereby increasing the generator voltage and tending to maintain the current. In this way rapld acceleration of the Vehicle is obtained.

In ascending a grade the vehicle slows up and the counter electromotive force of the motor decreases and the motor tends to draw an excessive current from the generator and stall the engine. This increase in current through the swit h solenoids actuates the switch and inserts resistance in the field circuit of the generator. lhis cuts down the generated voltage and limits the current to a Y desired value Which will not overtax the engine.

1 claim:

1. In an electrlcal switch, an electrical switch member having a serles of consecutive positions at which different electrical circuit connections are made and broken, a series of sprin s held under initial tension, and means tor consecutively engaging the springs by the switch in passing between each switching position, each spring being continued in engagement to the limit of the switch movement and further tensioned.

2. In an electrical switch, an electrical switch member having a series ofcontact fingers and contact buttons engaged thereby, a shaft, and springs under initial tension carried by the shaft for actuatin the fingers at different angular positions 0 the shaft.

3. In an electrical switch, a series of interconnected spring contact fingers and contact buttons engaged thereby, a shaft, and springs under initial tension carried by the shaft for engaging the contact fingers at different angular positions of the shaft and lifting the fingers from the buttons.

MILLAED COLE SPENCER.

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