US1747310A - Centrifugal switch - Google Patents

Description

Feb. 18, 1930.

7 A. MAYER CENTRIFUGAL SWITCH Filed July 31, 1926 i Patented Feb. 18,

UNITED STATES when PATENT orrlce CENTRIFUGAL SWITCH Application filed 11113731, 1926. Serial No. 126,321.

- of which friction is eliminated in its func-.

tioning parts and at the contact points of the circuit make and. break device. v

It is a further object to so construct the device that the usual end shake of the armature shaft has no influence on the make and break points, or gap when functioning and to this end it is proposed to mount the governor in such a manner that it will virtually form an integral rotating part of the rotary element of the motor assembly.

With the foregoing and other objects in view, the invention consists in the combination of parts and in details of construction hereinafter set forth in the ensuing specification and appended claim, certain embodi-- ments being illustrated in the accompanying drawings, in which:

Figure 1 is aside elevation, partly in section of the governor as applied to the rotary shaft of an electric motor;

Figure 2 is a View in detail of the centrifugal weight units;

Figure 3 is a sectional view taken along line 33 of Figure 1;

Figure 4 is a detailed view in front elevation of the insulating block;

Figure 5 is a detailed view in front elevation of the metal plates.

Referring more particularly to the draw ings, there is shown a fragmentary portion of an electrical motor p having an armature shaft a. In the usual type there is a consid erable end-shake between its armature bearings. However, in the present case, there is mounted on this shaft a a metal sleeve 6 insulated from the shaft by an insulating sleeve 0. The portion of larger diameter of sleeve 6 has recesses d arranged in its periphery, as

shown in detail in Figure 3, for the insertion and fixed mounting at its extremities of a spring h forming a loop to which are secured along this loop centrifugal Weights f.

Suitably mounted on the armature shaft 12 is an insulating block 9 carrying posts 2' and threaded plates Z. A washer m is arranged between the plates Z which are secured to the posts 71. The block g, posts i,plates Z, and washer m form an integral unit which re volves with the armature shaft as a unit. The threads in the plates Z areformed in such a manner as to not precisely match in order to produce a stiffness against automatic change ofposition of the adjustable contact screw n. One of the plates may also be springy to produce the same result, or a lock nut or any other suitable arrangement could be used for this purpose.

The other contact point is located at the apex of the spring h. Contact springs c, hearing against the sleeve 6 and a similar pair against the unthreaded end of the adjustable contact screw n, carry the current to the two make-and-break speed regulating contact points at is.-

When the armature shaft, and the assembly connected thereto rotates, the centrifugal force on the weights 7 produces a recession from, or approachment of the contact points" in a rectilinear and axial direction, and a consequent release or engagement of the contact carried by the spring k with the adjustable contact screw n, according to the variance in speed of the motor driven shaft a. Adjustment of the contact screw 92 thus respectively accelerates or retards the speed of the armature, according to the setting of the contact screw n. I

Speed regulating, motor driving'circuitis such that when the motor is at rest, contact points 7070 are closed, allowing passages of driving current and starting the 'motor. From a suitable generator, dynamo or battery 8 a lead from one pole oes directly to the motor. The other pole is connected to one pair of contact springs c, passing current thru Zak, governor springs h, hub Z), other pair of contact springs 0, to the motor. A suitable resistance is shunted across Zak. If on switching on current, the motor runs too slow, it shows. that the generator is deficient and therefore not suitable. If the motor runs too fast, the weights ff will cause a break of current at k, and the current to the motor will now be furnished through R only, which is not sufficient, and points Zak will again make contact. On retracting the contact screw n, or I advancing it, if too much retracted, themakeand-break is so regulated that the" desired speed of the motor is obtained.

By reason of the fact that both contacts of the circuit make-and-breakdevice are mount ed so as to rotate in unison with each other and the armature shaft, there is'iio possibility of friction being produced in their contacting it, acted upon by the centrifugal force create with each other. .The elasticity of the sprin by the rotating weights f, produces the only motion employed to make or break the speed controlling contacts.

Furthermore, the usual end-shake of the armature has no influence on the make-andbreak contacts as both rotate and move with the shaft, being virtually integral parts thereof. V

' Having thus described my invention, I

claim: 'An automatic electrical speed regulator for an electrical motor, said regulator being fixedly mounted on a rotary element of said motor and adapted to rotate with said element and comprising a make-and-break device arranged in the motor driving electrical circuit,

said device employing a plurality of loop springs with peripherally arranged weightsand a contact (point attached to the a ex of said loops, an

thus freely suspende with relationto said rotary element, the other contact being adj ustably mounted independently of, outside of and in proximity to said first contact which is centrifugally operable by means of said weights to cause rectilinear movement of the contact carried thereby, said device being so arranged as to rotate as a unit for the purpose of, maintaining a constant contact gap independent of end thrusts present within the rotary element.

In testimony whereof I afiix my signature. I ADOLPHUS MAYER,

Images