US2336917A - Electric contact - Google Patents

Description

Dec. 14, 1943. w. ARON ELECTRIC CONTACT Filed Feb. 11, 1942 Patented Dec. 14, 1943- UNITED STATES. PATENT, jorricr:

miaiil ittm Werner Aron, Dunstable, England Application February 11, 1942, Serial No. 430,465 In Great Britain February 7, 1941 7 Claims.

The invention relates to electrical contact mechanisms and, more particularly, to those which in operation are continuously closed and opened. i

It is an object of this invention to ensure reliable operation of such contact mechanisms, particularly by eliminating. faults due to irregular spacing of the contacts which may either be too widely spaced or tend to stick together.

It is another object of the invention to improve existing contact mechanisms of this character, an d,to effect repair thereof cheaply and easily andwithout dismantling, when they are worn.

It is still another object of the invention to make it possible to dispense with the use of precious metals such as platinum or special alloys such as tungsten alloys for the contacts or points thereof, and to obtain satisfactory operation with cheaper and less rare metals.

A preferred application of the invention is its use in connection with fractional horsepower electro-motors having an armature which is not connected to any outer circuit. In such motors The invention further comprises in a controlsystem for a small electric motor, an electric contact mechanism for controlling the winding.

of said motor by opening and closing the circuit of said winding synchronously with the rotation of said motor, comprising a pair of maincontacts adapted continuously to make and break said circuit, and an intermediate contact resiliently located between said main contacts.

The invention further comprises an electric contact mechanism comprising a pair of main contacts adapted continuously to make and break circuit by both moving simultaneously away from and towards one another, and an intermediate contact located resiliently between said main contacts.

In the accompanying drawing an embodiment of the invention as applied to the contact mechanism of a fractional horsepower motor of a dry shaver is shown by way of example. The lid or cover of the dry shaver is shown removed.

The insulating casing of the appliance is denoted I, the fixed and reciprocating cutters 2, 2. 3 are the coils of the field electromagnets 4, and 5 is the armature which rotates on shaft 6 carrying the cam l. Coils 3 are.supplied with current through the plug and socket connection 8 and flex 9. On the other hand the coils 3 are connected to the resilient contact blades I0 forming a make and break mechanism controlled by the cam l which bears on the insulating strips ll fixed to said blades causing said blades to move towards and away from each other, separating only a short distance.

When the contact ends of blades l!) are worn out they may either stick together thus failing to break contact or they may be too far remote for making contact at all. By inserting an independent resilient tongue l2 of simple leaf spring formation (i. e. supported at one end and entirely free at the other) preferably carrying a contact piece l3 at its free end between the main contacts of the blades ID th above mentioned difficulties were overcome without any mending cf the main contacts themselves.

The resilient tongue l2 was attached to a bar M which, in turn, was connected to a thin plate I5 clamped between the insulating casing l and the likewise insulating lid (not shown) of the dry shaver, by means of one of the clamping screws I 6,

In operation the tongue l2 cscillated between, and independent of, the cam operated blades I0 alternatively making contact with both of them simultaneously, and breaking contact with at least one of them. It could be observed that the sparks Were continuously changing their places thus spreading the inevitable wear over the whole surface of the contacts. Accordingly a dry shaver which had become inoperative through its special alloy contacts being burnt out was put into, and kept in, improved operation for many weeks by inserting an ordinary brass contact piece between the burnt main contacts.

Starting of fractional horsepower-motors of this kind which hitherto had to be eifected by twisting the armature shaft could now be obtained simply by switching on the current as the independent oscillation of the tongue sufficed al-- ready at certain angles for the initial breaking of the contact.

It has been found particularly advantageous to make the intermediate contact end in a sharp edge. This seems to have a favourable influence on the breaking ofthe sparks between the contacts.

The tongue 12 could be of conductive material and fixed to an insulating point or it could be made of insulating material and carry a conductive contact piece only. In this case it could be fixed to a Iron-insulated point, if desired.

The tongue could be inserted without any alterations into an existing dry shaver by the user himself or by any non-skilled shopkeeper or shop assistant which made it unnecessary to send the appliance to a special repair work shop. or course in the design of new appliances provision can be made for arranging a resilient tongue which would increase the value of the dry shaver for the owner who would even prefer to pay an increased purchase sum to gain the advantage of having the uninterrupted use of his appliance, and of saving costs for its repair.

Although the invention is described with reference to dry shavers its scope reaches beyond that of such and similar appliances as e. g. electrical hair cutters for men and animals. The invention may be applied to all electric contact mechanisms, particularly to those continuously actuated by mechanical or electrical means, such as with screen wipers, light signals or electric ignition circuits of internal combustion engines. The tongue according to the invention may even be applied between the brushes and worn out commutators of electromotors or dynamos.

What I claim and desire to secure by Letters Patent is:

1. An electric circuit controlling mechanism, comprising a pair of spaced, relatively movable main contacts connected in a common circuit, an auxiliary contact member disposed between said main contacts for common engagement therewith but normally spaced therefrom, said auxiliary contact member being yieldingly mounted so as to be freely movable with either of said main contacts on engagement therewith on opening and closing of the common circuit, and means for relatively moving said main contacts towards and away from each other and into and out of common engagement with the intermediate auxiliary contact member to respectively close and open the common circuit aforesaid through the intermediate auxiliary contact member, said auxiliary contact member being normally wholl outside of said common circuit except when in engagement with the main contacts.

2. An electric contact mechanism, comprising a pair of main contacts connected in a common circuit, an intermediate auxiliary contact device of simple leaf spring formation (that is supported at one end and entirely free at the other) located between said main contacts, and means for producing continuous relative vibratory electrical connection between said main contacts is continuously made and broken through said intermediate auxiliary contact device whereby said common circuit is continuously established and disestablished.

3. An electric contact mechanism, comprising a pair of main contacts connected in a common circuit, an intermediate auxiliary contact device movement between said main contacts whereby tact device being entirely disconnected from the I aforesaid common circuit save for its function in establishing said common circuit.

4. An electric contact mechanism, comprising a pair of main contacts connected in a common circuit, an intermediate auxiliary contact device of simple leaf spring formation (that is supported at one end and entirely free at the other) located between said main contacts, and means for continuously vibrating both of said main contacts simultaneously away from and toward one another whereby electrical connection between said main contacts is continuously made and broken through said intermediate auxiliary contact device, whereby said common circuit is continuously established and disestablished.

5. An electric contact mechanism, comprising a pair of main contacts connected in a common circuit, an intermediate auxiliary contact device of simple leaf spring formation (that is supported at one end and entirely free at the other) located between said main contacts, and means for producing continuous relative vibratory movement between said main contacts whereby electrical connection between said main contacts is continuously made and broken through said intermediate auxiliary contact device whereby said common circuit is continuously established and disestablished, said intermediate contact being so arranged that at some period during the vibratory cycle said auxiliary intermediate contact is free from both main contacts.

6. An electric contact mechanism comprising a pair of main contacts connected in a common circuit, an intermediate auxiliary contact device consisting of a flexible strip of insulating material carrying at its free end a contact located between said main contacts, and means for producing continuous relative vibratory movement between said main contacts whereby electrical connection between said main contacts is continuously made and broken through said intermediate auxiliary contact device whereby said common circuit is continuously established and disestablished.

7. In a control system for a small electric motor, an electric contact mechanism comprising a pair of main contacts connected in circuit with said motor, an intermediate auxiliary contact flexibly mounted between said main contacts, and means for producing continuous relative vibratory movement between said main contacts in synchronism with the rotation of said motor whereby electrical connection between said main contacts is continuously made and broken through said intermediate auxiliary contact and the motor circuit is continuously established and disestablished.

WERNER ARON.

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