US2291249A - Electric motor switch - Google Patents

Description

July 28, 1942. E. NIELSEN ELECTRIC MOTOR SWITCH Filed Oct. 28, 1940 MW@ 2 a, 3 a f M 2 a m,

Patented July 28, 1942 ELECTRIC MOTOR SWITCH Emanuel Nielsen, Racine, Wis., assignor to Scovill Manufacturing Company,

Waterbury,

Oonn., a corporation of Connecticut Application October 28, 1940, Serial No. 363,128

2 Claims.

This invention relates to electric motor switches and particularly to a switch which is of sturdy construction and dependable in operation but small and compact so as to fit in a limited space within the casing of a drink mixer motor or the like.

The main object of the invention is to provide mean for preventing arcing between the fixed and movable contacts. The construction is such that when the movable contact member is being moved across the fixed contacts, the movable contact point will mak direct contact with a fixed contact point and will be raised relatively to said fixed points while moving from one to the other, whereby the movable contact member is prevented from occupying any position intermediate two fixed contacts excepting in a plane sufl'iciently raised from the fixed contacts to insure freedom from arcing.

By raising the movable contact member from one contact point and lowering it onto another, wear of the points is avoided.

Another object is to arrange the movable contact member and the plate on which th fixed contacts are mounted in such manner that all the wiring connections can be made on the lower surface of said plate, whereby the wiring for supplying current to the movable as well as to the fixed contacts extend directly between the fixed contact plate and the motor fields, without interfering with or being in the path of movement of said movable contact member.

In the drawing:

Fig. 1 is a vertical sectional view of part of a motor casing in which is mounted a switch embodying my invention.

Fig. 2 is a plan view of the switch, detached, showing two positions of the movable contact member.

Fig. 3 is a front elevation of the switch show ing the movable contact member in a position intermediate two contact points on the fixed contact plate.

Fig. 4 is a plan view of the fixed contact plate, detached.

Fig. 5 is a plan view of the movable contact member, detached.

Figs. 6, '7 and 8 are vertical sectional views taken in the planes of the lines 6-6 of Fig. 4, I--I of Fig. 5 and 88 of Fig. 4, respectively.

In that embodiment of the invention shown in the drawing, the switch i mounted in the upper end of a motor casing III, on studs I l depending from the casing ID. The switch comprises a fixed contact plate l2 and a movable contact member I3, the plate I2 being secured to the studs II by screws H which extend through apertures I5 in the plate.

The fixed plate I2 is made of insulating material and preferably is elongated as shown. Near one end are three fixed contact points I6, I! and I8 which extend through the plate and are arranged in the arc of a circle having its axis coincident with th aperture l9. Intermediate the fixed contact points, between said points and the center I9, are two semi-spherical knobs 28, 2I. At the other end of the plate I2 is a flat elongated contact strip 22, the ends 23 of which extend through the plate I2 and are bent so as to hold the strip in position.

Leads 24, 25 and 26 are soldered or otherwise suitably connected to the fixed contact points I5, I! and I8, respectively, and a lead 2'! is similarly connected to the end 23 of the contact strip 22. The leads are tapped into the motor fields (not shown) in a familiar manner.

The movable contact member I3 comprises a contact arm 28 and a handle 29 Of insulating material, the handle extending at right angles to the conductor plate 30 on top of the arm 28. Said conductor plate 30 has 2. depending contact point 3! which extends through the arm 28 at one end. The plate 30 is bent at its opposite end so as to extend through and under the movable contact member I3 to provide a wiper end 32 adapted to contact the strip 22 on the plate I2. On the under side of the movable contact member I3, slightly inwardly of the contact 3|, is a semi-spherical knob 33 adapted to ride over the knobs 20 and 2| on the plate I2.

Th member I3 is held on the plate I2 by a headed stud 34 fixedly mounted in the plate I2, the movable member I3 being rotatable on the stud. A coiled spring 35 is held compressed between the head 36 of the stud and said member I3, the tension being such that the member I3 is urged toward the plate l2 to make contact between the point 3| and points I6, l1, l8, and between the wiper 32 and strip 22, but permitting the movable member l3 to tilt upwardly at one end when the knob 33 rides over the knob 20 or 2I.

If the knob 33 extends through the arm 23, an insulating sheet 3! is provided to separate said knob from the conductor plate 30.

The switch shown herein is a speed control switch, each of the contacting positions indicating a different motor speed, but the construction is adaptable for switches including an ofi position.

The handle 29 projects from the casing III for easy manipulation by the operator. Normally the contact point 3| contacts one of the fixed points l6, 11 or l8. The wiper contact 32 and contact strip 22 are constantly in contact. When the handle 29 is actuated from the full line position of Fig. 2 to the dotted line position, the arm 28 is raised and the contact between points 3| and I6 is broken as soon as the handle 29 is moved, because the curved surfaces of the knobs 33 and 28 come into contact and space the plate l2 and arm 28 apart. The arm 28 cannot come to rest excepting when the contact point 3| registers with points l6, I! or III, or when the knobs 33 and 20 or 2| are exactly in register as shown in Fig. 3. However, the slightest movement of the handle 29 will cause the arm 28 and its knob 33 to slip off the knob 20 or 2| to assume a circuit closing position. Thus arcing and wear of the points is prevented.

Changes may be made in details of construction without departing from the scope of my invention.

I claim:

1. An electric motor switch comprising a movable contact member and a fixed contact plate having an upstanding headed stud providing a combined sliding and pivotal connection for said contact member, resilient means on said stud between its head and said contact member, a plurality of contact points on said plate located at one side of said pivotal connection, a contact strip fixed to said plate on the other side of said pivotal connection, a protuberance on the surface of the plate located intermediate adjacent contact points and inwardly thereof between said points and said pivotal connection, said movable contact member comprising arms extending in opposite directions from said pivotal connection, an operating handle on said contact member extending at a right angle to said oppositely extending arms and radially of said pivotal connection, a contact point on one arm adapted to register with each of the plurality of contact points on said plate, a conductor bar on said contact member extending longitudinally on said arms and across said pivotal connection, and having one end in electrical contact with said contact point on said one arm, a wiper contact on said conductor bar at the opposite end of the other arm in contact with said contact strip on said plate, and a protuberance on the underside of said first mentioned arm adapted to register with a protuberance on said fixed plate for sliding and raising said contact member on said stud while rotating the same thereon to maintain said wiper and contact strip in electrical contact at the end of one arm of the movable member while the contact point at the end of the other arm is raised in passing from one contact point to the next on said plate.

2. A switch as claimed in claim 1, in which the conductor bar at one end extends through the movable contact member arm and is bent to underlie the arm in wiping relationship to the contact strip on the fixed contact plate.

EMANUEL NIELSEN.

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