US2285665A - Control apparatus - Google Patents

Description

June 9,1942. R. c. JONES 5 CONTROL APPARATUS Filed March 16, 1940 INVENTOR Rm?! 0 Jones;

Patented June 9, 1942 CONTROL APPARATUS Ruel C. Jones, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 16, 1940, Serial No. 324,418

5 Claims.

My invention relates, generally, to control apparatus and, more particularly, to switches of the type which are commonly referred to as reversing switches an example of which is described in Patent No. 1,872,342, issued August 16, 1932, to L. G. Riley.

It is the usual practice to provide such switches with secondary or auxiliary contact members in addition to the main contact members. The auxiliary contact members are utilized for interlockswitch, which is designed to interrupt the power circuit, that the line switch will always be opened before the main contact members of the reversing switch are opened and the line switch will not be closed until after the main contact members are well closed. Therefore, it is essential that the auxiliary contact members be positive in operation and be operated at the correct time with reference to the position of the main contact members on the switch.

Accordingly, an object of my invention, generally stated, is to provide auxiliary Contact members which may be readily applied to a switch having main contact members.

A more specific object of my invention is to provide auxiliary contact members for a switch of the type described in Patent No. 1,872,342.

Another object of my invention is to provide auxiliary contact members which are actuated directly by the operating mechanism of a switch.

A further object of my invention is to provide auxiliary contact members for a switch which are actuated at definite times during the operating cycle of the switch.

Other objects of my invention will be explained fully hereinafter or will be apparent to those skilled in the art.

In accordance with my invention, the auxiliary contact members on a switch are actuated by the same eccentric which actuates the operating mechanism for the main contact members. The auxiliary contact members are so disposed that they are not closed by the eccentric until it nears the end of its travel, thereby insuring that the main contact members are closed prior to the closing of the auxiliary contact members. Likewise, the auxiliary contact members are opened prior to the opening of the main contacts.

For a fuller understanding of the nature and objects of my invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawing, in which:

Figure l is a view, in front elevation, of a switch constructed in accordance with my invention;

Fig. 2 is a view, in plan, of the switch shown in Fig. l; and

Fig. 3 is a detail view of a portion of the switch shown in Fig. 1.

Referring to the drawing, a switch II), which is illustrated therein, is of the same type as the one described in the aforementioned Patent No. 1,872,342. The switch l0 may be utilized for reversing the direction of the flow of current through motors or other electrical apparatus by transferring the motor conductors from one electrical circuit to another.

Since the switch I0 is fully described in the aforementioned patent, it will not be described in detail in the present application. Briefly, the switch it comprises three stationary contact members l2, l3 and M which are mounted upon a panel The fixed contact members are disposed to be engaged by two movable contact members I5 and I6.

With a view to providing a simple and positive means for actuating the movable contact members l5 and I6 into and out of engagement with the stationary contact members, an air engine 2| is also mounted on the panel I. The air engine 2| is of well known construction and comprises pistons 23 and 24 which are disposed in cylinders 25 and 26, respectively. Admission and exhaustion of air to and from the cylinders 23 and 24 may be controlled by magnet valves (not shown) also of a Well known type. The pistons 23 and 24 actuate a rack 21 which rotates a pinion 28.

In order that the contact members l5 and I6 may be actuated by the air engine 2|, work arms 3| and 32 are connected to the contact members Hi and I6, respectively. Each of the work arms comprises a pair of spaced bars which are pivotally mounted at their upper ends upon the frame of the air engine 2| and are pivotally connected at their lower ends to the movable contact members, The work arms 3| and 32 are actuated simultaneously by a cross-head 33 which, in turn, is actuated by the pistons of the air engine 2|. In the present embodiment, the cross-head 33 is actuated by means of pivotally mounted lever arms 34 which are actuated by eccentric pins 35 on the pinion 28. A bearing block 36 is mounted on each eccentric pin 35 and is disposed between the forked arms of each one of the lever arms 34, thereby actuating the lever arms as the eccentric pin 35 is rotated back and forth by the rack 21.

In order to apply pressure to the contact members l5 and I6 to maintain sufficient pressure between the contact members of the switch to enable them to conduct currents of a high value, springs 31 and 33 are interposed between the cross-head 33 and the work arms-3| and 32, respectively. The springs 31 and 38 are so disposed that the cross-head 33 applies pressure to the movable contact members I5 and I6 when they are actuated to their opposite positions from that shown as well as in the positions shown. Maximum pressure is applied to the contact members when the eccentric pins 35 are in either one of their extreme positions of travel.

It will be seen that the contact members are retained in a closed position by the eccentric pins 35 and the levers 34 when the eccentric pins are moved past center. Therefore, it is not necessary to maintain air pressure in the cylinders in order to maintain the switch in either of its closed positions.

As explained hereinbefore, it is customary to provide switches of the type herein described with secondary or auxiliary contact members which are used for interlocking purposes in the control system of which the switch forms a part. In prior constructions, the interlock was of the type in which sliding auxiliary contact members were operated by movement of the lever 34 through a link connected to the lever 34. Considerable difliculty has been experienced in properly adjusting interlocks of the sliding type because of the fact that there is very little movement of the lever 34, while the springs are being deflected after the main contact members touch. Since the purpose of the interlock is to prevent the line switch, which is connected in the power circuit with the main contact members of the reversing switch, from closing until the reverser is operated and essentially the maximum pressure is applied to the contact members, it is desirable that the interlock not be closed until the eccentric pin has reached approximately its maximum position of travel, at which position maximum pressure is applied, as explained hereinbefore.

In accordance with my invention, the movei ment of the bearing block 36 in the forked operating lever 34 is utilized to actuate the auxiliary or interlocking contact members. As shown by the curve 39 in Fig. 3 in which the bearing block movement is plotted against rotation of the operating pinion 28, there is very little movement when the eccentric pin is at the center of the piston travel. However, as the eccentric pin moves toward the end of its travel, the vertical movement increases in rate until it attains a maximum as the eccentric pin reaches the extreme lateral position and is just about to go over center. Since there is still a slightly additional movement to securely lock the lever and contact mechanism in place, this movement is utilized to operate a simple interlock.

As shown in the drawing, each interlock comprises a piece of tempered clock spring steel 4| one end of which is connected to a terminal 42 and secured to a terminal block 43 by means of a screw 44, and the other end of which is bent back on itself to form a bend of a large radius. The terminal block 43 is secured to the panel H by a screw 45. The spring 4| carries a movable contact member 46 which is disposed to engage a stationary contact member 41 connected to a terminal 48 and mounted on the channel H by a screw 49. The stationary contact member 41 may be adjusted in position by means of a screw 5|.

A fiber plug 52 is disposed in the end of the bearing block 36 to engage the bent end of the spring 4| to deflect the spring and close the contact members 46 and 41, thereby completing a circuit through these contact members. In this manner, mechanical jarring of the auxiliary contact members is prevented by the resiliency of the spring 4| and also, allowance is made for slight variations in travel of the fiber block 52.

Referring again to Fig. 3, which illustrates the position of the eccentric pin 35 and the fiber block 52 when the main contacts of the reversing switch first touch as the eccentric pin is being operated toward the position shown in Fig. 1, it will be seen that the tip of the plug 52 is at the point 53 on the curve 39. Furthermore, it will be seen that the spring 4| is not engaged by the plug 52 until it has almost reached its extreme position at the point 54 on the curve 39 as illustrated by the dot and dash lines. Thus, the contact members 46 and 4! are not closed until the eccentric pin is substantially at the end of its travel and maximum pressure has been applied to the main contact members of the switch, as explained hereinbefore.

As shown in the drawing, an additional pair of auxiliary contact members, similar to those described, is provided on the right hand side of the switch ID. This pair of contact members is operated in the same manner when the eccentric pin 35 is at its other extreme position of travel and the main contact members 5 and I6 are thrown to their opposite positions.

From the foregoing description, it will be seen that I have provided auxiliary or interlockin contact members for a switch which are positive in operation and are not closed until after the main contact members of the switch are closed and substantially full pressure is applied to the main contact members. Likewise the auxiliary contact members are definitely opened before pressure on the main contact members is reduced and the main contact members are opened. Therefore, the interlock herein described may be safely utilized to control the operation of a protective switch which is connected in a power circuit with a reversing switch of the type herein described. It is obvious that the interlock disclosed in the present application may be utilized with switches of other types and for other purposes than that herein described.

I do not desire to be restricted to the particular form or arrangement of parts herein shown and described since it is evident that they may be changed and modified without departing from the spirit and scope of my invention as defined in the appended claims.

I claim as my invention:

1. In a switch, in combination, a pair of main contact members, resilient means for pressing said contact members into engagement, a rotatable eccentric pin for compressing said resilient means, a pair of auxiliary contact members, and means rotating with said eccentric pin for actuating said auxiliary contact members into engagement by rotative movement of said eccentric pin only after said resilient means is compressed.

2. In a switch, in combination, a pair of main contact members, resilient means for pressing said contact members into engagement, means for compressing said resilient means, a rotatable eccentric pin for actuating said compressing means, a pair of auxiliary contact members, and means rotating with said eccentric pin for actuating said auxiliary contact; members into engagement by rotative movement of said eccentric pin only after said resilient means is compressed.

3. In a switch, in combination, a pair of main contact members, resilient means for pressing said contact members into engagement, a crosshead for compressing said resilient means, a rotatable eccentric pin for actuating said crosshead, a pair of auxiliary contact members, and means carried by said eccentric pin for actuating said auxiliary contact members into engagement by rotative movement of said eccentric pin when said resilient means is substantially fully compressed.

4. In a switch, in combination, a pair of main contact members, an eccentric pin rotatable to a plurality of positions for actuating said contact members into and out of engagement, a pair of auxiliary contact members, and means rotating with said eccentric pin for actuating said auxiliary contact members into engagement by rotative movement of said eccentric pin at each of its extreme positions of travel, each pair of auxiliary contact members being closed only when said eccentric pin has reached substantially the end of its travel in a predetermined direction.

5. In a switch, in combination, a main stationary contact member, a main movable contact member disposed to engage the stationary contact member, a lever mechanism for actuating said movable contact member into and out of engagement with said stationary contact member, an eccentric pin for actuating the lever mechanism, an auxiliary stationary contact member, a resiliently mounted auxiliary movable contact member disposed to engage the auxiliar stationary contact member, and means carried by said eccentric pin for biasing said auxiliary movable contact member into engagement with the auxiliary stationary contact member after said lever mechanism has been operated to actuate the main movable contact member.

RUEL C. JONES.

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