US2662143A - Protected switch - Google Patents

Description

H. W. ECKLES PROTECTED SWITCH Dec. 8, 1953 Filed Feb. 25, 1950 Patented Dec. 8, 1953 UNITED STATES PATENT OFFICE Emerson Electric Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application February v25, 195i), Serial No. 146,236

1 Claim. 1

Th present invention relates generally to electric switches, and more particularly to a starting switch for electric motors and the like which incorporates contacts protected against fouling from dust or other matter.

There has long been a need in the woodworking power tool art for a starting switch for the motor of such tools that will not become fouled by sawdust and the like. As is well known, a starting switch is open during utilization of the power tool, since its function is fulfilled as the motor reaches a predetermined speed, so, with presently used switches, sawdust and the like settles on the stationary and movable contacts as the power tool is used. Hence, the contacts become fouled and do not pass current, requiring frequent cleaning. Often the contacts are seriously damaged, both electrically and through careless cleaning.

Therefore, an object of the present invention is to provide a novel switch which incorporates protective means for the contacts.

Another object is to provide a novel switch which includes a substantially dustproof cover or housing for the contacts constructed to move with the movable contact including a resilient member maintaining the same substantially sealed.

Another object is to provide a novel switch incorporating protected contacts which is of simplified, inexpensive, sturdy, efficient construction.

Other objects are to provide a novel switch incorporating protected contacts which reduces maintenance to a minimum, Which functions repeatedly and indefinitely without fouling, and which otherwise fulfills the long felt need.

The foregoing and other objects and advantages are apparent from the following description taken with the accompanying drawing, in which:

Fig. 1 is a plan view of a starting switch incorporating the teachings of the present invenof the present invention. A mounting base 12 of insulating material supports a stationary contact i l secured thereto by an integral rivet it, the rivet It also anchoring a stationary contact terminal E8 to the base l2.

The base l2 also supports a resilient conductive blade 20 which includes a returned mounting portion 22 anchored by rivets 23 to the base 12, a divided body portion 2G, and diverging legs 28 to the free ends of which are secured pads 28. A terminal extension 29 is formed integral with the mounting portion 22. A housing in the form of a flanged cup it is secured to the body portion 24 by an interiorly disposed movable contact 32 through an integral rivet 33 so that the movable contact 32 is in opposed relation to the stationary contact M and the latter extends into the cup 30, but is in spaced realtion to the walls thereof (Fig. 4). A phenol resin flat washer 3 1 or the like and a metal washer 36, illustrated in the form of a cup, but which may be flat, surround the stationary contact it and are biased toward the flange of the cup to by a spiral spring 38 which also bears against the base i2. The spring 38 is effective to maintain the washer 3G in substantially sealing relation with the flange of the cup 30 at all times, a one and a half to three ounce spring having been found suitable to insure good closing engagement.

A stop member 32 limits breaking or withdrawal movement of the blade Ell through a T- head ts (Fig. 3). The stop member 62 is anchored to the base I? by the rivets 23 which extend through a support portion 46, and it extends through the opening between the arms 26 of the blade 20.

Two terminal posts it and 50 are mounted on the base 12, the former of which has a lead 49 soldered to the terminal 2i). A lead til connects the terminal post 50 with the terminal it.

In operation, as is well known, the pads 23 are engaged by a sliding sleeve indicated at 52 by broken lines to close the switch iii in the starting of the motor with which it is associated. At a predetermined speed of such motor, cen trifugal force effects sliding of the sleeve 52 to free the blade 20.

It is to be noted that in the closing and open" ing actions of the contacts 32 and I l, both remain fully protected by the cup Bil and washer 34, the latter being maintained against the former by the spring 38 at all times. Sawdust and other such matter cannot reach the contacts 32 and 14 to foul them. An airtight relation between the washer 34 and the wall of the contact 3 I6 is not necessary for a continuously operating starting switch, as has been demonstrated under sustained operating conditions.

In Fig. 5 is a modified construction which differs from that previously described in the spring elements. A spring washer 54 replaces the spring 38, as does a flat metal washer 56 the cup washer 35, the spring washer 54 maintaining the washer 34 in closing relation with the cup 30. A second flat metal washer 58 is added as support for the spring washer 54.

Manifestly, there has been provided a starting switch construction which fulfills the objects and advantages sought therefor.

It is to be understood that the foregoing description and the accompanying drawing have been given by way of illustration and example. It is also to be understood that changes in form of the elements, rearrangement of parts, and substitution of equivalent elements, which will be obvious to those skilled in the art, are contemplated as within the scope of the present invention which is limited only by the claim which follows.

What is claimed is:

In an electrodynamic machine, switch construotion comprising, in combination, a base, a stationary contact supported thereon, a movable switch blade supported thereon, a movable contact on said switch blade in opposed make and break relation to said stationary contact, a cup member surrounding said movable contact and supported by said switch blade for movement therewith, said cup member surrounding a portion of said stationary contact including its contact race, a nonconductive washer movably disposed about the stationary contact and engaging the open face of said cup member, a resilient metallic compression member interposed between said washer and said base for biasing the washer continuously against said cup member for movement therewith, and a stop member supported on the base for withstanding the biasing load of said compression member when the contacts are predeterminately separated and thereby preventing uncupping of the contact faces.

HOWARD W. ECKLES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 473,717 Varley, Jr Apr. 26, 1892 1,313,856 Cavanagh Aug. 19, 1919 1,405,537 Milton Feb. '7, 1922 2,181,586 Perryman et al Nov. 28, 1939 2,192,25 Boynton Mar. 5, 1940 2,232,535 Junizen Feb. 18, 1941 2,339,675 Bucklen, Jr. Jan. 18, 1944 2,454,873 Hollins et a1 Nov. 20, 1948 2,491,272 Knapp Dec. 13, 1949 2,520,441 Schwaneke Aug. 29, 1950

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