US2020977A - Speed control mechanism - Google Patents

Description

Nov. 12, 1935. I o. F. WARNER ET AL SPEED CONTROL MECHANISM Filed Aug. 20, 1931 mw a a m PP aaym mw w e t v A k r 2 w mm .a mm m Ill UNITED STATES PATENT OFFICE SPEED CONTROL MECHANISM Donald F. Warner, Lynn,

derwick, Marblehead,

and Reginald G. Stan- Mass., assignors to Gencral Electric Company, a corporation of New York ApplicationAugust 20,

13 Claims.

In connection with certain types of driven machines, it is desirable to adjust certain parts of the driven machine and at the same time adjust the speed of the driving machine. Such an in-' stance is met with, for example, inthe case of motor driven grinders wherein as the grinding wheel wears down it is desirable to adjust the guard for the wheel and to adjust the speed of the motor so as to maintain the peripheral speed of the wheel at the desired value. With such machines it is desirable also to provide an emergency governor for limiting the speed The object of the present invention is to provide in connection with a machine of the type referred to an improved construction and arrangement of emergency speed governor, and for a consideration of what we believe to be novel and our invention attention is directed to the following specification and the claims appended thereto.

In the drawing, Fig. 1 shows a known type of grinding machine provided with adjusting and governing means embodying our invention; Fig. 2 is a diagrammatic view comprising a wiring diagram, and Fig. 3 is a sectional view of the emergency governor.

7 Referring to the drawing, Fig. 1 shows a grinder of the swing frame type, the frame I being hung on a chain 2- and being movable by 30 means of the handles 3. Mounted in the frame is a grinding wheel 4 driven by a variable speed electric motor 5 by means of a belt 6. Located over the grinding wheel is a guard l which is adjusted toward the left in Fig. l as the wheel wears down, the adjustment being effected by means of a threaded rod 8 having a handle 9 at its end. The details of structure for effecting adjustment of the guard is not shown as it forms no part of the present invention. The arrangement indicated is a known one. Mounted on the frame adjacent to guard 1 is a contact box Ill in which is located a field resistance N (Fig. 2) for adjusting the'speed of the motor. The switch arm l2 of the contact box is connected by a link 13 to guard 1 so that the switch arm is moved when the guard is adjusted. At I4 is indicated i the motor starting box comprising the starting resistance I5 and the holding coil l6 for the contact arm ll, the latter being biased to open or 0 off position.

Mounted on motor shaft I8 is an emergency governor or speed limiting governor comprising a spindle l9 which is fixed in an opening in the 5 end of the shaft and is suitably insulated therefrom as is indicated at 20 (Fig. 3); The outer 1931, Serial No. 558,339 (c1. 51-99) end of spindle 19 comprises a yoke 2| between the arms of which is pivoted an eccentric emergency governor weight 22, the pivot being indicated at 23. As shown in Figs. 2 and 3, the upper end of Weight 22 is the heavy end and is in the 5 form of a contact arm 24. Weight 22 below pivot 23 as shown in Figs. 2 and 3 is provided with a conical bearing seat 25 with which engages a bearing cone 26 carried on one end of a tube 27. The other end of tube 21 is slidably mounted in 10 a washer 28 of insulating material mounted in a sleeve 29, and located between washer 28 and a flange on tube 21 is a governor spring 39 which presses bearing cone 26 against seat 25. Sleeve 29 is slidably mounted in a. slip ring or contact 1. cylinder 3| formed integral with yoke 2|. Mounted on slip ring 3| is a second slip ring or contact cylinder 32 insulated therefrom by an insulating sleeve 33. When motor shaft I8 rotates, spindle I9, yoke 2|, governor weight 22, 20 tube 21, sleeve 29 and cylinders 3| and 32 rotate with it as a unit. This rotating unit is located in a casing 34 the inner end of which is fastened to the end frame 35 of the motor. Mounted in casing 34 are contact brushes 36 which engage slip rings 3| and 32. In the end of sleeve 29 is a thrust bearing ball 31 which engages the end of a rod 38 suitably connected to the link l3. In the diagrammatic view of Fig. 2, the rod 38 forms a continuation of link l3. Rod as is slidably mounted in a suitable bearing in the end wall of casing 34. With this arrangement when guard l is adjusted, sleeve 29 is moved axially to adjust the compression of spring 30. The emergency speed governor per se is claimed in our divisional application, Serial No. 21,052, filed May '11, 1935.

Referring to Fig. 2, it will be seen'that resistance II is connected in series with the motor field and that brushes 36 and slip rings 3| and 32 of the emergency governorare located in the cir- 40 cuit of holding coil Hi. The circuit through the emergency governor comprises the governor Weight 22, the circuit being closed as long as contact end 24 engages slip ring 32. V

In the use of the invention, emergency governor weight 22 is set by means of spring 30 for a speed slightly higher than that at which it is desired to run the grinding wheel. When the motor is running arm I! closes the circuit through holding coil I6 and this circuit is maintained closed as long as the desired speed is not exceeded. In case the desired speed is exceeded, governor weight 22 will fly out, moving from the full line position, thus movingcontact end 24 from engagement with slip ring 32 and opening 5 circuit is opened through automatically to ofi position,

.pression of spring gency governor weight for the newrmotor speed.

fore the wheel is worn away.

In accordance with the provision of the patent V 7 an adjustable part, a adjustable emergency speed governor, and means connecting said adjustable part to said adjustthe circuit coil is, arm l'l moves opening the motor circuit When guard I is adjusted to take care of wear of the grinding wheel and to increase the speed of the motor by adjusting resistance H, at the same time rod 38 is moved to change the comthus adjusting the emer- With this arrangement, therefore, when the driv en machine is-adjusted, the speedof the driving machine and the setting of the emergency governor for the driving machine are "correspond- I governor for the motor,

adjusting means and said.

ingly adjusted.

The emergency governor is relatively simple in structure and when used in the combination il-. lustrated is automatically adjusted without anyspecial act on the part of the operatoryand with; out requiring the exercise of any special skill by theoperator. It .may be adjusted when the mo- --tor is running, a thing of importance in connection with mechanisms of this type.

While we have described our invention as applied to a grinder, itwill be understoodrthat this is only by way .of example and that the invention maybe used wherever found applicable. Broadly, the control mechanism for controlling and limiting the speed of ,a machine comprises in accordance with our invention a speed controlling element orspeed governor and a speed limiting element or emergency governor together with 'means for'automatically setting one of these elements, in response to the'set'ting of the other element. The invention nection with a grinder hasgreat utility in con- .for to .obtain the most efficient. operation it is desirable that the grinder wheel be operated alwayslat the highest safe peripheral speed. ,This requires that as the f wheel wears down the speed be correspondingly increased, the increase becoming considerable bestatutes, we have described the principle of operation of our invention, together with the apparatus which we now considento, represent the best embodiment thereof, but it understood that the apparatus shown is only illustrative and that the invention may be car--' ried out .by other: means.

we desire to have What we claim as new and des i re tosecure by Letters Patent of the United States, is:--

1.'In combination, a drivenrnachine having driving machine having adjustable means for controlling its speed and an 7 able means and to said emergencygovernor for 'speeds, and me speeds, a

7 speed governor adjusting thespeed of the driving machine and the setting of the emergencygovernor when said for setting the emergency governor for different governor setting means. 7 l V r 3.In'combination, a driven machine, a; variable speed electric motor for driving it, means for adjusting the speed of the motor, an emer means for gency speed governor for .themotor, setting the speedlzatwhich, the emergency govthrough holding coil it. When the emergency governor for the driving machineymeans ans'ror simultaneously. adjustingj "said speed adjusting means and said emergency ernor operates, and means for adjusting the speed of the motor and correspondingly adjusting the setting means for the emergency governor.

4. The combination with a grinding wheel and a variable speed motor for driving it, of an ad-' justable emergency speed governor for the motor, and'means for and correspondingly adjusting the emergency governor as the grinding wheel wearsdown.

with a grinder having a part which is adjusted as:

v 5. The combination grinding wheel and a the grindingwheel wears down, a motor for driving the grinder, means for adjusting the speed of the motor, and anhdjustable emergency speed s of means connecting said part to said speed s for adjustingthem when 'said part is adjusted; o In combination, chine driven'thereby, means for adjusting the speed of the motor, an emergency governor for the motor, and means for adjusting said speed adjusting means andcorrespondingly adjusting the setting of the emergency governor, said emergency governor comprising a contact in the motor circuit, an eccentric governor weight having: a contact. arm adapted to engage said contaet, a

adjusting the speed of the motor a governor spring which holds said weight against ;tioned in accordance witha con ition of the driven 4o chine having an adjustable part which is posimachine, comprisinga driving machine, means for adjusting the speedof the driving machine, a speed limiting governor for the driving machine,

means for adjusting the speed limiting governor,

and means adapted to be connected to the ad- -justab1e part of a, driven 'machine for corre-i spondingly adjusting said two first named means 7 when the adjustable part is adjusted.

. 9..An arrangement for operat ng machine 'having a grinding wheel and an adjusta grinding able part'associated therewith comprising a driv- 7 ing machina'means for adjustingthe speed of the. driving machine, a'speedlimiting governor ior thedriving'machine, means, for adjusting the; 7 speed limiting governor,

and means adapted to be connected tolthe adjustable part of a grinding qmachine for correspondingly radjustingfsaidrtwo first'named means whensuch adjustable part is 1 adjusted,

10. An arrangement for operating a grinding diiierent speeds, comprising a driving machine,

, machine having a grindingwheel tobe operated ingmachine, means for adjusting the speedlimiting governon-and means for simultaneously cer- ?respondingly adjusting 5 said ,means.

two first I named 11. An arrangement for operatinga: grinding machine having a grinding wheel tojlb'e opera ated at difierentspeeds comprising anelectric motor, a speed limiting governor for the motor, 13. The combination with a grinding wheel, an means for changing the setting of the speed limadjustable guard for the grinding wheel, and a 12. The combination with a grinding wheel, a governor, movable means for varying the speed variable speed machine for driving it, and a of the driven machine, and means connecting for simultaneously correspondingly adjusting said DONALD F. WARNER. two movable means as the grinding wheel wears REGINALD G. STANDERWICK. d V

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