US3030480A - Holding means for instruments - Google Patents

Description

United States My invention relates to holding means for electrical instruments, and particularly to holding means for instruments, such as relays of the type having movable parts for effectively locking the movable parts against movement during shipment or handling of the relay to prevent damage which might otherwise result from such handling or shipment.

More particularly, my present invention relates to holding means for locking against movement the thermal element of a thermal relay, employing for the control of signaling devices used in connection with railway signaling systems, a bimetallic strip heated by a heater element for actuating contacts at the expiration of a predetermined time interval after the application of power to the relay.

One well-known form of thermal relay employs a first bimetallic strip supported through the medium of an oppositely disposed bimetallic strip with the first strip carrying a heating element and the first strip being so disposed relative to an adjacent contact strip that the heat generated by the heating element causes the first strip to deflect in a direction toward the contact strip, the period of time preceding the engagement of the first strip with the contact strip being predetermined generally in accordance with the initial position of the first strip relative to the contact strip.

Thermal relays of the type described are frequently employed in railway signaling circuits to provide a predetermined time interval between the functioning of related circuits of the system. It will be apparent that when thermal relays are so used it is essential that there be little variation between the predetermined time interval selected during manufacture and assembly of the relay and the actual time interval of the relay during operation following the shipment and installation thereof. Unless some means are provided to prevent the thermal element of the relay from experiencing excessive oscillatory movement during such handling of the relay, damage may result to the thermal element to cause, for example, an undesirable variation from the predetermined time interval, which damage would otherwise be prevented if the thermal element were held relatively fixed when the relay is not in use.

One object, therefore, of my invention is to provide improved holding means which, when used in connection with a thermal relay, effectively locks the thermal element thereof from harmful movement without bending or stressing the thermal element to avoid disturbing the time calibration of the relay.

Another object of my invention is the provision, in a thermal relay, of a mounting device, in which device the rotary motion of a driving screw is translated into linear motion of a pin for preventing excessive oscillatory movement of a sensitive element which is to be protected.

Still another object of my invention is to provide novel holding means which is effective for preventing the delicate and movable parts of a relay from undergoing harmful and injurious movement.

Yet another object of my invention is to provide improved holding means for protecting during shipment or handling the delicate parts of an instrument, which means is relatively inexpensive to manufacture and assemble.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

atent ice In accordance with my invention, and to attain the aforementioned objects, I provide holding means for cooperating with a thin strip member carried by the bimetallic element of a thermal relay, said holding means including a housing secured to the base of a cover member of the relay, a pin disposed in the housing and vertically movable between extended and retracted positions and provided with bifurcated portions at its one end nearest to the thermal element, biasing means for biasing the pin toward its retracted position, and a driving screw adjustably mounted in the housing and accessible from the exterior of the relay for driving the pin toward its extended position in which the bifurcated portions of the pin extend on either side of the strip member to prevent excessive lateral movement of the bimetallic element.

I shall described one form of relay having applied thereto one form of holding means embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings:

FIG. 1 is a side elevational view partially in section showing one form of holding means embodying my invention applied to a thermal relay.

FIG. 2 is a front elevational view of the relay shown in FIG. 1 with certain of the parts removed, the holding each of the several views.

Referring to the drawings, the relay 10 comprises an L-shaped frame member 12 of suitable non-magnetic material, such as aluminum. The frame member 12 consists of a vertical portion 12a and a horizontal forwardly extending portion 12b. A contact block 13 is secured to portion 12a of frame member 12 as by screws 13a, and a transparent cover member 14 is in turn secured to contact block 13 and portion 12b of frame member 12 by means of suitable screws 16. A-top plate 18 of suitable insulating material, such as Bakelite, is secured to the portion 1212 at the underside thereof by screws 20. The top plate 18 supports in verticaldepending relation three downwardly extending contacts which include a fixed front contact 22, a thermal element TE, and a fixed back contact 24.

The construction and arrangement of front contact 22, back contact 24 and the thermal element TE are described and claimed in Letters Patent of the United States No. 2,371,018, granted to Harry E. Ashworth and Selden B. .Aylsworth on March 6, 1945, for Thermal Relay. Inasmuch as these parts by themselves form no part of my invention, it is deemed unnecessary to describe them herein in detail, and only so much of the structure of these parts will be described as is necessary for a full understanding of the holding means embodying my invention.

As will be obvious from an inspection of the drawings, the front contact 22 and back contact 24 are each provided with suitable means for adjusting their positions relative to thermal element T-E to enable the desired time calibration to be obtained. The thermal element TE comprises a main bimetallic strip 26 secured at its upper end to an oppositely disposed auxiliary bimetallic strip 28. Auxiliary strip 28 in turn is rigidly fastened to a rigid strip 30 secured by means, not shown, to top plate 18. The main strip 26 is provided at its lower end with an insulating block 31 carrying a low resistance contact member 32 for cooperation with back contact 24, a low resistance contact member 34 for cooperation with front contact 22, a .thin rectangular metallic strip 35, the ends of which extend outwardly from block 31 at its opposite sides for a purpose which will be made clear as the specification proceeds. Front contact 22, back con-tact 24, and contact members 32 and 34 are provided with flexible connectors 36, 38, 40 and 42, respectively. The flexible connectors 36, 38, 40 and 4-2, and two addition-a1 flexible connectors 44 and 4-6 to be hereinafter described, are intended to be connected at their free ends to suitable contact strips 47 provided in contact block 13.

The main strip 26 carries a heating element 52 insulated from strip 26 by suitable insulating means such as, for example, a layer of asbestos not shown. The heating element 52 is provided with a pair of electrical terminals not shown which are intended to be connected to flexible connectors 44 and 46 by means of rivets 54 and 54a (FIG. 2) mounted in the insulating block 31 adjacent the opposite sides thereof.

When the parts are at ambient temperature, the contact member 32 engages back contact 24 to close the contact 3224, and contact member 34 is spaced from front contact 22 so that contact 3422 is open. When heating element 52 is energized, the heat is transferred to strip 26 by radiation, and this heat causes the strip 26 to defiect in a direction toward front contact 22 to open contact 3 2-24 and to close contact 34-22. These positions of the contacts when heating element 52 becomes energized are fully illustrated in the previously mentioned reference patent. The opening of contact 32-24 will occur at the expiration of a 'very short time interval after heating element 52 becomes energized, but contact 34 22 will not become closed until the expiration of a relatively long time interval after heating element 52 become-s energized.

In accordance with my present invention, 1 protect thermal element TE from becoming damaged due to excessive vibration during shipment or handling of relay by providing a locking pin 56 having bifurcated portions 562: and 56b. The bifurcated portions 56a and 56b of pin 56 are provided adjacent their tipped ends with inner chamfers 56c and 56d, respectively, and pin 56 is so disposed relative to the strip 35 that during periods when relay 10 is not in operation pin 56 may be operated to an extended position in which the bifurcated portions 56a and 56!) thereof are disposed closely adjacent both sides of the strip 35 substantially as shown in FIG. 3, and in a manner now to be described.

Referring now to FIG. 3, the pin 56 is mounted in a tubular housing or casing 58, which housing 58 is provided with a vertical hole 58a for receiving pin 56. A lower portion 58b of housing 58 of slightly reduced diameter extends outwardly of relay 10 through a hole 60 provided in the base of cover member 14, the lower portion 5812 being formed with an annular split pin 58c rolled back to engage the underside of cover member 14 in a manner to firmly afiix the housing 58 to relay 10. The housing 58 is provided with an internal screwthreaded hole 58d which extends vertically from the exterior of relay 10 to the base of the other hole 58a in the housing. A driving screw 62 concentric to pin 56 extends upwardly through the screw-threaded hole 58d and abuts at its upper end against an annular shoulder 64 integral to pin 56. By rotating screw 62 in the proper direction, pin 56 may be operated to an extended position in which it is shown in FIG. 3 for at times preventing lateral movement of thermal element TE and a retracted position to become disengaged from the strip 35, or at other times permitting normal operation of the relay. To limit the movement of pin 56 toward its extended position, the housing 58 is provided adjacent its upper end with aligned transverse holes 66 (FIG. 4), which holes are adapted to receive the spread-apart ends of a pin 68 located with respect to pin 56 such that it is always disposed between the bifurcated portions 56a and 56b. It will be noted that pin 56 is guided by the pin 68 as pin 56 moves toward its extended position. The pin 68 further functions to prevent pin 56 from rotating in the hole 58a, thus preventing pin 56 from becoming misaligned relative to strip 35. Located within the annular space of the hole 58a and mounted between pin 68 and the shoulder 64 of pin 56 is a coil spring 70 for returning pin 56 from its extended position. To move pin 56 to its extended position, the screw 62 is screwed into housing 58 by means of a screw driver (not shown) or other similar conventional tool inserted into a saw kerf 72 provided in screw 62. As the rotation of screw 62 is continued, the rotational movement of screw 62 is translated into linear movement of pin 56, causing pin 56 to be carried upwardly until the bifurcated portions 56a and 56b thereof extend sufiiciently beyond the lower end of strip 35.. The bifurcated port- ions 56a and 56b in the extended position of pin 56, thus, in a sense, engage strip 35 to consequently permit only an insignificant degree of lateral movement of thermal element TE. When it becomes desirable to place the relay in service, the direction of rotation of screw 62 is reversed and pin 56, under the influence of spring 70, is backed off to a position in Which bifurcations 56a and 561; no longer interfere with the movement of strip 35. It will be understood that screw 62 may be retained in housing 58 to prevent the entry of foreign substances into the housing.

By properly selecting the characteristics of spring 70 a considerable pressure may be applied to screw 62 at the point of its engagement with shoulder 64 of pin 56 at times when pin 56 is out of engagement with strip 35. Maintaining the spring pressure on the driving screw will have the effect of preventing externally caused vibration from gradually loosening screw 62 and causing the screw to eventually escape from the housing. This obviously has the advantage that the screw always remains in position in the relay and is available for use at any time.

One advantage of holding means embodying my invention is that it provides a simple and effective way for protecting the sensitive thermal elements of a thermal relay during shipment without aifecting the calibration of the relay.

It is to be understood, of course, that my invention is not limited for use only in connection with thermal relays, but is applicable in its broader aspects for use with various other types of relays and electrical instruments in which it is desired to protect the sensitive parts thereof during shipment.

Although I have herein shown and described a specific construction of holding means as evidenced by the accompanying illustrations, I do not desire to limit myself to the particular relation of their parts or other details of construction or arrangement, as various changes may be made within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, an electrical instrument having an operating element movable between a normal position and an operated position, a support member fixed with respect to said element and provided at its one end with a screw-threaded hole aligned with said element when said element is in its normal position, a screw screwed into said screw-threaded hole, a locking pin slidably mounted in said member and biased to a retracted position in engagement with said screw and movable by said screw from its retracted position to a projected position adjacent to said element when said element is in its normal position, and means on the free end of said locking pin for engaging said element to prevent its movement when said locking pin is in its projected position and said element is in its normal position.

2. In combination, a relay having an operating element movable between a normal position and an operated position, a support member in said relay fixed with respect to said element and provided at its one end with a first hole and provided at its other end with a second screw-threaded hole concentric with said first hole and in communication therewith, said first and second holes being in alignment with said operating element when said operating element is in its normal position, a screw screwed into said screw-threaded hole, and a locking pin slidably mounted in said first hole and biased to a retracted position in engagement with said screw and movable by said screw from its retracted position to a projected position in which the free end thereof engages said operating element when said element is in its normal position to prevent movement thereof.

3. In combination, a relay having an operating element movable between a normal position and an operated position, a support member fixed with respect to said operating element and provided at its one end nearest to said operating element with a first hole and provided at its other end with a second hole concentric with said first hole, a locking pin slidably mounted in said first hole and movable from a retracted position spaced from said operating element to a projected position, a driving member adjustably mounted in said second hole and movable toward and away from said operating element, spring means caged in said first hole for biasing said locking pin into engagement with said driving member, whereby when said driving member is moved away from said operating element said locking pin is urged by said spring means to its retracted position, and means on the free end of said locking pin for engaging said operating element to prevent its movement when said locking pin is in its projected position and said operating element is in its normal position.

4. In combination, a relay having a cover and having a part movable between a normal position and an operated position, said cover having an opening therethrough in alignment with said part when said part is in its normal position, a support member mounted at one end in said opening, said support member provided at said one end with a screw-threaded hole aligned with said part when said part is in its normal position, a screw screwed into said screw-threaded hole, a locking pin at the other end of said support member slidably mounted in said support member and biased to a retracted position in engagement with said screw and movable by said screw from its retracted position to a projected position, and a bifurcation on the free end of said locking pin arranged relative to said part such that the branches of said bifurcation extend alongside the opposite sides of said part to prevent its movement when said part is in its normal position and said locking pin is in its projected position.

5. In a relay comprising a part movable between normal and operated positions and including a cover for said part, said cover having an opening therethrough in alignment with said part when said part is in its normal position, and means for holding immovable within predetermined limits said part for shipping purposes, said holding means comprising, in combination; a support member mounted at one end in said opening and provided at said one end with a first hole extending to a point outside said cover and provided at its other end with a second hole concentric with said first hole, the diameter of said first hole being less than the diameter of said second hole, a driving member slidably mounted in said first hole and movable forwardly into said second hole, a locking pin slidably mounted in said second hole and biased to a retracted position in engagement at its one end with said driving member and movable from its retracted position by said driving member to a projected position in which the other end thereof engages said part when said part is in its normal position to prevent its movement, and means secured to said support member for preventing said locking pin from being ejected from said support member by said driving member during its forward movement.

6. In combination, an instrument having a part laterally movable between a normal position and an operated position, a cover for said part having an opening therethrough in alignment with said part when said part is in its normal position, an elongated housing in said instrument mounted at one end in said opening, said one end of said housing being provided with a first hole accessible for entry from outside of said cover, the other end of said housing being provided with a second hole concentric with said first hole and said second hole communicating with said first hole, a locking pin slidably mounted in said second hole, a driving member slidably mounted in said first hole and movable toward and away from said locking pin, spring means caged in said second hole and bearing on said locking pin for biasing said locking pin to a retracted position in engagement with said driving member, said driving member effective when moved toward said locking pin for carrying said locking pin from its retracted position to a projected position, and means on the free end of said looking pin for engaging said part to prevent its lateral movement when said locking pin is in its projected position and said part is in its normal position.

7. In a relay having a part movable between normal and operated positions in which movement of said part when it is in its normal position is at times desired to be prevented, the combination comprising a support member fixed with respect to said part and provided at its one end with a screw-threaded hole accessible for entry from the exterior of said relay and provided at its other end with a second hole concentric with said screw-threaded hole and communicating therewith, a first pin secured to said support member and diametrically disposed across the mouth of said second hole, a second locking pin slidably mounted in said second hole and provided with a projecting shoulder and provided at its one end nearest to said part with a bifurcation the branches of which project alongside the opposite sides of said first pin thereby preventing said locking pin from rotating relative to said part, a screw threaded in said screw-threaded hole, and spring means in said second hole interposed between said first pin and said shoulder for yieldably biasing said locking pin to a retracted position in which it bears on said screw, whereby when said part is in its normal position and said screw is adjusted a predetermined amount said locking pin is moved thereby from its retracted position to a projected position in which said branches extend on the opposite sides of said part to prevent its movement.

References Cited in the file of this patent UNITED STATES PATENTS 901,013 Knott Oct. 13, 1908 2,125,399 Sayre Aug. 2, 1938 2,351,097 Boeringer June 13, 1944 2,371,018 Ashworth et al. Mar. 6, 1945 2,390,479 Watson et al. Dec. 4, 1945 2,872,548 Christensen Feb. 3, 1959 2,965,747 Secofsky Dec. 20, 19Q

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