US2493897A - Speed responsive switch - Google Patents

Description

Jan. l0, 1950 J. l.. PETz ETAL SPEED RESPONSIVE swI'rcH 2 Sheets-Sheet 1 Filed June '7, 1947 ATTor-:NEY v,

Jan. `l0, 1950 J. PETZ Erm.

SPEED RESPONSIVE SWITCH 2 Sheets-Sheet 2 Filed June 7. 1947 INVENTORS JOHN CHARLES G. BALLIETT ATTORNEY Patented Jan. 10, 1950 2,493,897 SPEED RESPONSIVE SWITCH John L. Petz, Poughkeepsie, and Charles G. Balliett, Rochester, N. Y., assignors to International Business Machines Corporation, New York, N. Y., a corporation of New York Application June 7, 1947, Serial No. 753,192

4 Claims. (Cl. 200-80) switches and more particularly to that type of .speed responsive switch which is commonly used in governor controlled electric motors of the adjustable speed type used in oflice appliances, such as typewriters.

An object of the present invention is to provide an improved speed responsive switch having better regulation characteristics.

An object is to provide an improved speed responsive member for actuating switch contacts.

An object is to provide an improved switch structure for a speed responsive switch.

An object is to provide a switch structure which is simple in construction, easy to assemble, and more rugged than prior structures of this nature.

An object is to provide a simplermeans of adjusting the contacts of a speed responsive switch to vary the speed.

An object is to provide a speed responsive switch which is more accessible for servicing than formerly was possible.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a side elevation, partly in section, showing the speed responsive switch attached to an electric motor.

Fig. 2 is a horizontal section on the line 2-2 in Fig. 1.

Fig. 3 is a vertical section on the line 3-3 in Fig. 2.

Fig. 4 is a vertical section on the line 4- 1 in Fig. 2.

Fig. 5 is a side elevation of the speed responsive member as viewed from the right in Fig. 2.

In the drawings the reference numeral IU designates an electric motor of the universal type, having a .commutator andbrushes. The main motor'casing or housing has an extension I0a which acts as a housing for the speed responsive switch and this housing is closed by an end plate Il which is of the same general shape as the housing I0a in Fig. 3 and is attached thereto by three screws I2 threaded into suitable internal bosses IIlb formed in the housing IIla.

The numeral I3 (Figs. 1, 2, and 4) designates the motor shaft which extends a short distance into the housing I0a and has secured to it a large hub I4 on which is mounted the speed responsive This hub is removably attached to the motor shaft I3 by means of two headless set screws I5 disposed 90 apart about theperiphery of the hub I4. The hub, at its right hand face (Fig. 2), is transversely slotted at Mb (Figs. 2 and 5) to receive a bowed springmember I8 which forms part of a centrifugal weight assembly.

The member I6 is held in the slot IIb by a narrow plate I1 (Figs. 2, 4, and 5) which is mounted on shallow shoulders alongthe edges of the slot Nb by staking the metal of the hub I4 in four places (Fig. 5) along the line llc adjacent the slot Hb, the metal being forced over the edges of the plate I1 by a chisel-shaped tool in a well known way. Due to the fact that the member I6 is bowed, the placing of the plate I1 in place slightly compresses the member I6 which is spring-tempered so as to hold said member fairmember which controls the governor contacts.

ly firmly in place in the slot ,I lb.

The bowed member I6 has a companion bowed vmember I8 (Fig. 2).. having a large hole Isa through which the motor shaft I3 passes (Fig. 2) and the two members I8 and I8 are held together by casting 2 bean-shaped weights I9 on the ends thereof as most clearly shown in Figs. 2 and 5, the members I6 and Il being preferably made of spring-tempered steel and the weight elements I9 of a soft, easily cast metal like lead or tin.

Considering the member I6 as fastened near its center, it is quite evident that, with rotation of the shaft I3 at a sulciently high speed, the weight members I9 will tend to move radially of the shaft I3 and thereby tend to straighten out the bowed members I6 and I8. Since the member I6 is constrained in the slotl Ilb against movement longitudinally fof the shaft I3 it is evident that the midpart of memberv I8 will tend to move to the right in Fig. 2. By properly proportioning the weight members I9 and properly tempering the spring members Il and I 8, the degree of movement of the spring member I8 may be made suitable for the desired range of speed over which the motor I0 is to operate in a specific piece of o'ice equipment, such as a typewriter, in which the motor is used.

The spring member I8 is enlarged where it encircles shaft I3 to form an eye designated I8b (Figs. 4 and 5)- to which is riveted a bridging member 20, the side pieces of the bridging member extending through axial slots I 4d-in the hub Il and the centr'al part of the bridging member .20 extending crosswise of the shaft I3 just in front of the plate I1, as most clearly shown in Fig. 5. It is apparent that the right hand motion of the member I8 in response to increasing speed 3 will cause the bridging member 20 to move to the right in Figs. 2 and 4. This bridging member is utilized to actuate the contacts which control the speed of the motor by shunting resistance in a well known way.

In order to provide ventilation for the motor, there is secured to hub |4 a fan element 2| having the lugs 2|a which act as fan blades to cause turbulence within the motor casing l0. In order to cause the air to follow more or less of a denite path, there is provided inside the housing |a a cylindrical member 22 of insulating material which is centered with respect to the shaft |3 and the armature of the motor I0 by means of the bosses |0b, the cylindrical member 22 being merely pressed into the housing. Also pressed into the housing and rmly against the right hand edge of the cylindrical member 22 is a disc 23 of insulating material having a large hole to permit entry of air into the space enclosed by the cylindrical member 22.' Thus the member 22 and the disc 23 act like a fan housing.

The switch mechanism which cooperates with the speed responsive element shown in Fig. is mounted on the end plate Il so that the entire switch may be removed for servicing ran adjustment without disturbing any of its parts. The switch mechanism includes a thick disc 24 oi insulating material which is freely slidably mounted on two pins Ila riveted to the end plate Il which permit the disc 24 to move axially with respect to the motor shaft |3 but prevent rotation of the disc. The end plate is provided with a large hole receiving a cup washer 25 which acts as a seat for a spring 26, the other end of which is seated in a circular recess formed in the disk 24. This spring normally tends to urge said disc to the left toward the end of the motor shaft I3.

Mounted on the disk 24 is a contact support plate 21 (Figs. 2, 3, and 4) which is attached by means of a screw 29 to the disk 24. This contact plate is provided with a terminal screw 29 by means of which a terminal lug 30 is screwed to the lower end (Fig. 3) of the plate 21. The terminal lug 30 is crimped to the stripped end of one of the wires 3| which leads to the resistance controlling the speed of the motor (not shown). To the upper end of the contact supporting plate 21 is secured a spring contact member 32 by means of a screw 33 threaded into the plate 21. The contact member 32 has fixed to it a circular post 34 having a socket in which is secured a button 35 which is in axial alignment with the end of the motor shaft I3 adjacent the cross-piece of the member 20, whereby movements of the member 20 in response to varying speed will be communi cated to the contact member 32.

The lower end of the contact member 32 (Figs. 2, 3, and 4) carries one of apair of contact points 36, the other of which is mounted on second contact plate 31 attached to the disk 24 by the screw 38. The plate 31 is similarly provided with a terminal lug 39 and terminal screw 40 corresponding to the terminal screw 29 and lug 30, which lug 39 is crimped to the other wire 3| leading to the speed controlling resistance. In order to provide maximum security for the wires 3| to prevent them from being detached from' the lugs 39, 39 by vibration, both of the plates 21, 31 are formed with bent-over lugs 21a and 31a, respec tively, which are located over the wires 3| at the time of assembly and serve to clamp said wires adjacent the lugs 30. 39 to the face of the disc 24 asshowninFigA.

Considering for the moment that the disc 24 is ilxed in the position of Fig. 2, it is quite apparent that, as the motor increases in speed. the member 2|) will move to the right and ultimately will engage the end of the button 35 and push the contact member 32 far enough to the right in Fig. 2 to open the contacts 36 and remove the shunt on the speed controlling resistance. The insertion of this resistance in the motor circuit will operate in the usual way to reduce the speed of the motor which, of course, will cause the member 20 to retreat to the left and permit the contacts 36 to reclose. By predetermining the position of the button 35 in relation to the member 20, it is possible to adjust the point at which the contacts open, thereby to adjust the speed of the motor which, once adjusted, will be maintained constant.

For the purpose of adjusting the speed of the motor, means is provided for adjustably moving the disc 24 toward and away from the member 20. Secured to the inside face of the end plate l I is a ilanged bearing ring 40 (Figs. 1 to 4) which loosely, rotatably supports a control lever 4| having the pointer and finger piece 4 ia by means of which the lever may be rotated on the inside of the ilanged ring 40 as a bearing, the lever 4| being attached to a large ring-shaped portion 4|b which is rotatable inside the flanged ring 40.

Also rotatable in the flanged ring 40 is a ring 42 which has three inwardly projecting lugs 42a (Fig. 3) which project inwardly toward th center of the ring 42 and engage the lands of a multiple thread 24a formed on the outer cylindrical surface of the disc 24. The lever 4| has a lug 4|c struck therefrom which extends to the right (Fig. 2) and downwardly across the right hand face of the ring 42. The lever 4| also is formed with an extension 4|d (Fig. 3) having a shallow bentover lug of a height approximately equal to the thickness of the ring 42. This extension 4|d is provided with a clamping screw 43 and a washer 44, the washer being on both the shallow lug on extension 4| d and the right hand face (Fig. 2) that is, the rear face (Fig. 3), of the ring 42. By means of the screw 43 and the washer 44 the ringshaped hub 4| b of lever 4| and the ring 42 are clamped together so as to rotate as a unit when the lever 4| is adjusted angularly to adjust the speed.

It is quite apparent that if the lever 4| is moved to right or left in Fig. 3 the ring 42 will be rotated and the lugs 42a will move in a fixed arc of a circle, and by cooperation with the threads 24a will act like a nut and cause the disc 24 to move to right or left (Figs. 2 and 4) to bring the button 35 closer to or further away from the member 20, thereby determining the point at which the speed responsive member in Fig. 5 takes eiiect to open the contacts 36.

The clamping screw 43 and washer 44 provide a means whereby the motor may be initially set at a definite speed for a definite position of the lever 4| in relation to the scale over which the pointer 4Ia moves when the motor is mounted in the machine. For the purpose of facilitating this adjustment after the motor has been assembled and particularly after the motor has been placed in the machine, the end plate Il is provided with a large slot IIb (Fig. 3) which permits access to be had to the screw 43 from the exterior of the motor.

'I'he connecting wires 3| preferably may be in a cable C which enters the housing |0 through a protecting bushing 45 (Figs. 2 and 3) pressed on the outer wrap of the cable so as to t rather snugly. The bushing 45 ts in a hole formed in the casing ilia and the casing ia is slotted between the hole for the bushing 45 and the outer or right hand edge of the housing. By removing the screws I2 the end plate il may be raised slightly in Fig. 2 far .enough to disengage the bushing 45 from its hole, the Wires 3| may be slipped out ofthe slot formed in the casing and the entire assembly carried by the plate Il with the attached cable removed for servicing, repair, or inspection without disturbing any of the critical adjustments. Any of the parts most likely to get out of order which are mounted on the plate il may be readily replaced and the assembly reintroduced in the housing Ilia with a minimum of time.

Furthermore. after the parts have been assembled it is a relatively simple matter to reset the ring 42 to determine the precise speed of the motor for any given setting of the lever H.

While there have been shown and described and pointed out the fundamental novel features of the invention, as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims:

What is claimed is:

1. In a governor controlled switch, a centrifugal force responsive element, a fixed contact member, a cooperating movable contact member actuated by said element, means for supporting said contact members including a disk having a thread on its periphery, a anged guide, a ring rotatable in said guide and having lugs extending into the lands of said thread, a control lever connected to said ring, a support for said guide, and means on said support for mounting said disk for axial movement on said plate in response to rotation o1' said ring.

2. In a governor controlled' switch, a shaft, a hub mounted on said shaft; a pair of bow springs arranged with their ends joined and their concave sides facing each other and with one spring secured intermediate its ends to said hub, a pair oi weight members secured to the' springs, one at each point of-junction, said weight members tending to straighten when the shaft rotates with increasing speed and thereby induce axial movement of the midportion of the spring which is free at its midportion; a xed contact member, a cooperating movable contact member actuated by the spring which is free at its midportion, means for supporting said contact members including a disk having a thread on its periphery, a flanged guide, a ring rotatable in said guide and having lugs extending into the lands oi said thread, a control lever connected to said ring, a support for said guide, and means on said support for mounting said disk for axial movement on said plate in response to rotation of said ring.

3. A governor controlled switch comprising, a

' support plate, a circular guide flange mounted on said plate, a non-current conducting element disposed in the opening in said flange, .and formed with a threaded portion concentric with said v flange, a ring rotatable in said flange and having 4. A governor controlled.' switch comprising, a

support plate, a circular guide flange mounted on said plate, a non-current. conducting element disposed in the opening insa'id flange and formed with a threaded portion-'concentric with said flange, a ring rotatable in said ange and having threaded engagement with said threaded portion, a control lever rotatable in said ilange and disposed alongsidemsaid-ringf means to adjustably connect said ring and said lever, means for slidably mounting said disk for axial movement when the said ring is turned by said lever, a spring pressing said disk axially so as to hold said ring and said lever against said flange, and contact means mounted on said disk for bodily movement therewith, a rotating shaft, a pair of bow springs mounted on said shaft and extending symmetrically on opposite sides of the shaft with their ends in contact and their concave sides confronting, one of said springs being secured at its middle to the shaft and the other being free to move axially of the shaft to actuate said contact means.

JOHN L. PETZ. CHARLES G. BALHE'II.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATEN'IS Number Name Date 1,795,240 Ulmer Mar. 3, 1931 2,311,409 Merrill Feb. 16. 1948 2,365,657 Naul Dec. 19, 1944 2,438,810 Lambert Mar. 30, 1948

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