US2182111A - Speed governor for electric motors - Google Patents

Description

Dec. 5, 1939. w. A. ANDERSON SPEED GOVERNOR FOR ELECTRIC MOTORS Filed June 29, 1938 A\ N IIIIIII INVENTOR WALTER A. ANDERSON 1? ATTORNEY Patented Dec. 5, 1939 UNITED STATES PATENT OFFICE SPEED GOVERNOR FOR ELECTRIC MOTORS Application June 29, 1938, Serial No. 216,464

1 Claim.

This invention relates to electric contact speed governors such as are used on accounting machines and the like, and more particularly to a speed regulating adjustment therefor.

I Adjustment devices of this character generally employ a set screw threaded in the flexible contact feather and arranged to be adjusted toward and from the actuating arm of a centrifugal govern'or. Such a device is disclosed in United States Patent No. 1,984,512, issuod to Walter A. Anderson on December 18, 1934. An unsatisfactory feature of this method of adjustment is that it is impractical to make the adjustment while the machine is running, necessitating therefore, several adjustments by trial and error method until a satisfactory operating speed is obtained. Another disadvantage of this type of adjusting device is that the governor housing must be removed in order to gain access to the set screw.

An object of the present invention, therefore, is to provide an adjusting means for an electric contact governor which is readily accessible and permits the desired speed regulation while the machine is running.

With this and incidental objects in view, the invention consists in certain novel features of construction and combinations of parts, the essential elements of which are set forth in the appended claim, and a preferred embodiment of which is hereinafter described with reference to the drawing which accompanies and forms part of the specification.

In the drawing:

Figure 1 is a perspective view of an electric contact governor embodying the invention,

Figure 2 is a right side elevation of the governor with the housing shown in section, and

Figure 3 is a sectional view taken on the line 33 of Figure 2.

The armature shaft I (Figures 1 and 2) has secured on its end a bracket 2 of rigid construction. A flexible actuating feather 3 is secured at one end to bracket 2 by screws 4 and carries a weight 5 at its other end, the center of mass of the weight being normally to the left (Figure 2) of the plane of rotation of the pivot point of feather 3, the pivot point being designated by the numeral 6. Feather 3 is of two-part construction, as shown, one of the parts having a go round boss I located at the axis of rotation of the armature shaft and feather. A rigid contact support 8 fixed on two sleeves II (Figure 3) is supported for sliding movement on two studs I2, and is held out of electrical contact with the studs by insulating material as shown. The support 8 carries a bearing I3 (Figures 1 and 2) in which is slidably supported a plunger I4 of hard insulating material. A cross bar I5 is mounted in insulated condition on studs I2 and is secured in spaced relation to support 8 for sliding move- 5 ment therewith by screws I6 passing through insulating bushings and collars I1 and threaded in the support. A contact feather I8 is fixed on bar I5 for sliding movement on studs I2,

and is likewise held out of electrical contact with 10 the studs by insulating material as shown. A thumb screw 2| journaled in a stationary bar 22 spanning and insulated from the ends of studs I 2 is threaded in cross bar I5 (Figures 1 and 3) to adjust support 8, plunger I4 and feather I8 as 15 a unit, bodily toward or away from actuating feather 3. Nuts 23 threaded on the ends of studs I2 hold the parts in assembled position as shown.

A knob 24, preferably of insulating material, is fixed on screw 2|, and extends through an aper- 20 ture in the governor housing (Figure 2) so as to be readily accessible. Feather I8 carries a set screw 25 in axial alignment with plunger I4, and carries a contact 21 to cooperate with a similar oppositely disposed contact 26 secured in support 25 8. Wires 2'8 and 29 carry current through support 8, contacts 26 and 21, and feather I8, and from there to the electric motor (not shown) so that the motor is supplied with current only while contacts 26 and 21 are closed. When current is 30 started through wires 28 and 29 and through the motor, armature shaft I starts rotating, whereupon weight 5 moves to the right about pivot 6 (Figure 2). Its amount of movement to the right increases with the speed of rotation of 35 armature shaft I. As weight 5 and feather 3 move to the right, boss 1 slides plunger I4 to the right, contacting the left end of set screw 25. Further acceleration of armature shaft I results in additional movement of the plunger I4 to the 40 right, causing feather I8 and contact 21 to be moved to the right away from contact 26. This breaks the circuit to the motor, causing it to decelerate until Weight 5 and the associated parts return a short distance to the left, at which 45 time contact 21 again touches contact 26, re-establishing the circuit. When these parts find their equilibrium, contacts 26 and 21 are made and broken in such rapid succession that the motor runs at a speed that is sufiiciently constant for practical purposes.

When it is desired to increase or decrease the speed of the machine, it is merely necessary to turn knob 24 clockwise or counter-clockwise respectively (Figure 1) to bring the contact unit 2t2l and plunger 06 farther from or nearer to the actuating feather 8. Adjustment of the speed in this manner can he made while the machine is g because the oi thumb screw 28 has no uence on the tension of one contact against the other. Rotation of knob 26 clockwise causes screw it to increase the distance between feather 3 and plunger l l causing contacts 26-21? to break later and thereby increase fine speed of the machine. Conversely, rotation of lsnnob 2t counter-clockwise decreases the distance between feather 3 and plunger it, causing contacts 2t-tl to break sooner and thereby reduce the speed of the machine. The thread of screw 20 is much finer than thatshown in the illustration in Egure 3, this thread being enlarged in the showing for clearness of illustration, making possible a very fine adjustment of the speed.

While the form of mechanism herein shown and described is admirably adapted to i the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form of embodiment herein disclosed, for it is susceptible of embodiment in various aisaiii forms all coming within the scope of the claim which follows.

. What is claimed is:

In a speed governor for an electric motor, a rotatable shaft, a bracket secured to one end thereof, an actuating feather having one end secured to the bracket and the opposite end provided with a weight and being free to move in a direction substantially parallel with the axis of the'shaft in response to changes in the speed of rotation of the shaft, a. stationary support, a rigid contact leather and a flexible contact feather, a carriage slidable on the stationary support and having secured thereto one end of each of the contact feathers, a. plunger slidably supported in the rigid contact feather at the axis of rotation of the shaft, one end of the plunger lying adjacent a portion of the flexible contact feather and another portion of the plunger lying adjacent a portion of the actuating feather, and a micrometer adjusting means for moving the contact feathers and plunger bodily toward or away from the actuating feather.

WALTER A. ANDERSON.

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