US2377830A - Speed responsive switch - Google Patents

Description

June 5, I v R VON REPYPERTT SPEED RESPONSIVE SWITCH Filed .Jan. 1, 1943 2 Sheets-Sheet 1 FIGJ. I 4/ JF- -i VENT OR A TTOHNE Y June 5', 1945.

R VON REPPERT 2,377,830

SPEED RESPONSIVE SWITCH Filed Jan. 1, 1943 2 Sheets-Sheet 2 Palented June 5, 1945 v SPEED RESPONSIVE SWITCH Richard Von Reppcrt, Rochester, N. Y., assignor to International Business 'Machines Corporalion, New

York

York, N. Y., a corporation of New Application January 1, 1943, Serial No. 471,039 2 Claims. (01. zoo-so) This invention relates to typewriting machines.

The main object of the present invention is to provide an improved speed governing device for motive power means of a machine requiring a constant source of speed power.

Another object of the present invention is to provide an improved speed regulating means for the driving motor of a power operated typewriting machine or other oflice appliance.

An object is to provid an improved contact controlling device for the speed governing means of propulsion motors such as are commonly used to operate typewriters and other off ce appliances.

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. l is a plan view partly in section.

Fig. 2 is an elevation partly in section.

Fig. 3 is a vertical section on the line 3-3 in Fig. 4 is a vertical section on the line 4-4 in Fig. 2.

Fig. 5 is a vertical section on the line 55 in his. 2.

Figs. 1 and 2 the reference numeral desighates the stator frame of an electrical propulsion motor, of the type commonly used in driving ofllce machines and appliances such as power operated typewriters.

,stantially changing the main features of construction which distinguish the present invention from the prior art.

- The frame I0 is formed with flat sides 10a and a flange Nb which is concentric with the shaft l l of the motor. Pressed on this flange isashield Fig. 6 is a vertical section on the line 8--t in A motor of this type is provided on the well known Electromatic typewriter and or guard lllc which is concentric with the shaft ii and may be made of insulating material. Se-

to the ends of the blocks [2. The opposite. endsof the blocks 12 are secured to the sides of the The frame It by means of screws it (Fig. 2).

frame; comprising blocks l2 and plate 1:, supports the control contacts, the speed regulating lever,

and mechanism associated with said lever for controlling the contacts as will be made clear hereinafter.

The'speed controlling mechanism is divided into two main groups or parts, one of which comprises a "centrifugal force operated mechanism mounted on the main shaft ll, while the other comprises the controlling contacts and a speed regi ilating lever carried by the frame including the blocks 12. The first group of parts consists of a disk 15 (Figs. 2 and 3) mounted on the shaft H by means of a hub 15a. Mounted on the outer face of the disk 15 is a U-shaped bracket 18 pivotally supporting a lever ll. One arm of the lever ll extends parallel with shaft H and is connected by a short link I8 to a weight member i9 in the form of a flat thin block or strip secured to a spring 20, which is clamped to a bracket 21 secured to the outer face of the disk T5. In order to counterbalance the weight of the parts so far described the disk i5 is provided with counterbalance elements 22 riveted to the outer face of said disk. These elements may be bored, milled, or filed as required to balance dynamically the assembly including the disk 15.

The other arm of the lever ll extends substan tially at rightangles to the shaft it into a transverse slot formed in a narrow extension 151: of the hub lbs and abuts the left hand end (Fig. 2) or rear end (Fig. 3) 'of.a pin 23 sliding in a bore in extension i5?) concentric, withsliaft H. The pin 23 is provided with a head 23c which limits left hand movement (Fig. 2) of the pin 23. When the motor shaft H rotates, the weight: member 19 tends to move' radiallyoutwardly of the shaft ii an extent commensurate with the speed of the shaft according to well known principles. In order-to prevent the weight member is from moving too far when the motor is operated near its limit of speed, as determined by the control mechanism, there is provided a stop pin 15c (Figs. 2 and 3). The assembly including the disk is and parts carried thereby rotates within the guard ills of the motor frame 10 as most clearly shown in Fig. 2. The outward movement of the weight member 19 in response to the centrifugal force created by the rotation of the disk l5 by shaft H is communicated to the pin 23 by the link 18 and lever Hjwhereby the pin tends to move to the right with reference to Fig. 2 as the speed increases. This movement of the pin is communicated to a contact memberll secured to a contact strip 25, the latter being provided with an offset bent-over lug 224: (Fig. 4) on which the contact-member 24 is mounted. The latter comprises a thin, narrow resilient strip of conducting material provided with a contact element 24a engaging a similar contact element on an definite position and is prevented from chatterstrip 25.

When the motor is at rest the contacts 24a are closed and shunt a speed controlling resistance which is placed in a suitable part of the motor circuit, in accordance with well known principles of motor control, according to the type of motor. As the speed increases, a point will be reached where the axial movement of the pin 22 in the extension l5b will be sumcient to move the head 224 into engagement with contact member 24 and separate the contacts 24a thereby opening the shunt for the resistance and reduce the speed of the motor.

Alternatively, if necessary, the lugs 25a, 26a carrying the contacts 2.4a. may be reversed so that the movement of the pin 22 closes the contacts 24a instead of opening them. In order to accomplish this it will be merely necessary to change the extent of ofiset of the lugs 25a, 22a to enable the contact member 24 to be placed in front, that is, to the left (Fig. 2) of member 26a (Fig. 4).

It will be seen from the foregoing that the head of the pin 22a will take a definite position for each definite speed necessary to produce a movement of the member i8.

Motors of this type usually operate at speeds which may range from about 2800 R. P.' M. to 3800 R. P. M., which requires that the spring 20 be made relatively stiif and the weight I! light in weight in order to avoid excessive spring tension which would result if heavy weights and springs were used. By using a relatively stiff spring 20 and a small weight I! it is possible for the governing mechanism to respond very quickly to small variations of speed. Thismakes it necessary that the natural period of vibration'of the elements I! and 20 on bracket 2| shall be well above the period of vibration at the highest speed, it being understood, of course, that when the motor is running at its highest speed it will tend to fluctuate above and below the desired speed which will, of course, cause the parts I! and 20 to vibrate on the bracket 2|. 7

Since the head of the pin 22 takes a definite position'for each speed and with a slight increase in speed'wlll move further" to the right (Fig. 2) to open the contacts 24a it is possible; by adjusting the member 24 along the axis of the shaft ll in relation to the head of the pin 22a, to adjust the speed of the motor as desired. For this purpose the contact strips 25, 28 are secured to the face of a member 21 which confronts the disk II. The member 21 conveniently may be made of a plate of insulating material and is guided for horizontal movement along the axis of pin 22 by means of pins l2a on each side of a downward extension 21a of the plate 21.

fined between a loose washer 29 and a washer 22 riveted to the end of the reduced portion 224. A cupped spring washer 2i interposed between .washer 22 and the shoulder in screw 22 presses plate 21 against washer 24 but enables the screw 22 to be turned to adjust plate 21 axially of shaft ll. Th'us plate 21 always is maintained am a the sheet as the plate rotates.

and plate 21 will move to the right with refer-' ing or vibrating on screw 22.

The screw 22 is threaded into a cam plate 24 provided with three cams 24a (Figs. 5 and 6) which are embossed in the plate to form three cam grooves 24b, the grooves beingarranged concentrically of the stud 22, but so shaped that the counterclockwise ends (Fig. 5) of the grooves are axially nearer the left hand end (Fig. 6) of the stud 28 than the clockwise ends. The plate 24 is pressed against three round-nosed studs 22 radially equidistant from the screw 22 and carried by the plate I 2. The studs 2| are shown in Fig. 5 as projecting into the clockwise ends of the grooves24b and, as viewed in Fig. 5, the grooves lead counterclockwise and forwardly of the plane of the sheet, or axially of the stud 22, whereby, it the plate 24 is rotated clockwise in Fig. 5, the plate 21 will also move rearwardly oi the plane of Thus the stud 22 once to Figs. 2 and 6, and tend to move the contact element 24 away from the head 22a of the pin 22.

plate 34 clockwise the full extent limited by the lengths of the cam grooves 24!), the pin 22 will have to move virtually to its other limit of travel before actuating the member 24 'sufiiciently to open the contacts 24a. This, of course, will occur at maximum speed and the maximum centrifugal force exerted on the weight IS.

The plate 24 is rotated by means of a manual setting member or lever consisting of plate 22 (Figs. 1, 2, 4, and 5) provided with three arcuate slots 22:: through which extend screw studs 2 threaded into three radially equispaced holes in the plate I 2. The latter has a suitable hole large enough loosely to receive a hub 24c (Figs. 2, 5, and 6) fixed to the plate 24 into which hub is threaded the screw 22. The outer or right hand end (Fig. 2) of the stud 22 is slotted and provided with a lock nut 22- which may be screwed up against the hub 240 to lock the stud as against rotation relative to plate 24. Interposed between the disk 22 and the plate II are friction washers 29 which may take the form of simple washers of resilient material such as spring steel or phosphor bronze bent along the diameter and have sumcient friction to hold the plate in any adjusted position.

For the purpose of rotating the plate 24 manually it is provided with an extension 22b (Figs. 1, 2, 4, and 5) having a pointer portion 220 bent at an angle to extension 22b. When the motor is properly installed in the machine the pointer portion 220 may cooperate with a suitable scale on the outer frame of the machine and the portion 22b extends through a suitable slot to enable theplate 22 to be moved through an angle approximately limited by the lentths ,of the slots 22a. For the purpose of holding the plate 24 in contact with the pins 22 there are secured to the'plate 22, intermediate the ends of the slots 22a, three leaf sprinzs 42 (Figs. 2 and 5) which press on the plate 24-near screw 22 and thus tend-to press the plate to the right in Figs. 2

and 6 against the studs 22 which are rounded in the edges of plate 34.

' to the motor circuits.

verse section. The plate. is keyed to the plate 36 by means of lugs 36d which are bent at right angles to the plate 36 and extendinto slots 34d Owing to the fact that the plate 21 is frictionally mounted on the end of the screw 28, the position of the contact member 2| may be initially adjusted relative to the head 23a of stud 23 by loosening the lock nut 38 and rotating the screw 28 by means of a screwdriver. This causes the plate 21 to move to right or left (Fig. 2) as the case may be relative to the plate 34. Thus if the lower limit of speed should be determined as 2800 R. P. M.,-the stud 28 may be turned until the contacts 24a barely open with the manual setting member 36b in the position of Fig. 5. Obviously it would be useless to adjust the contact member 24 to the point where the contacts 24a open at somelower speed as they would make it impossible to obtain the maximum speed allowed by the range of movement of plate 38.

In order to avoid the use of soldered connectionswhich might be broken from vibration, the e contact strips 25, 26 are provided with lugs b, 28b (Figs. 1 and 4) which extend into slots I 2a (see Fig. 2 also) formed in the plates 12 and extending parallel with the axis of rotation of the motor. The ends or these lugs bear against contact strips 4| secured in the slots l2a and having at their ends resilient portions a to maintain good contact with the lugs 25b, 26b and also with members. 42 such as buttons insulatably mounted on the motor frame In and connected This method of making connections between the governor controlled contacts 24a and the motor circuits makes it possible to disassemble the mechanism without unsoldering any connections and also provides a more rugged connection which is noteasily disturbed.

One or the practical advantages or the governor described herein is that all of the electrical connections and speed regulating parts are wholly enternal of the centrifugal force responsive elements of the system. In prior art the contacts are mounted on the disk I! requiring that electrical connections be made by means of a.

commutator device. These commutator devices not only increase the cost of the device .but create a great deal or trouble in service owing to deterioration of the brushes and commutator seg-:-

ments.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification 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. I

What is claimed is:

1. A speed responsive switch for use with retary mechanism having a switch actuating mem-- ber centrifugally displaced along an axis of rotation, comprising a support screw disposed axially of said member, manual adjusting means mountin said screw in said frame including a manual member movable to select a speed, a support plate mounted on the end of said screw conmanual adjusting means is operated to select a speed.

2. A- speed responsive switch for use with rotary mechanism having a switch actuating member centr'ifugally' displaced along an axis of rotation, comprising a support plate disposed transversely of and confronting one end of the actuating member, a second support platemounted between said member and the first plate, contact means mounted on said second plate and including a contact element actuable by said member with changes in the motor speed;

and means for mounting said second plate on the 'said first plate for movement axially or said member, including a manually adjusting member and an adJusting screw bodily movable axially oi the actuating member by said adjusting member, said second plate being mounted on the end of said adjusting screw.

l RICHARD VON'REPPERT.

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