US3544941A

US3544941A - Thermal relay

Info

Publication number: US3544941A
Application number: US779016A
Authority: US
Inventors: Otto Deissler
Original assignee: Starkstrom Schaltgeraetefabriken Sprindler Deissler and Co GmbH
Current assignee: Starkstrom Schaltgeraetefabriken Sprindler Deissler and Co GmbH
Priority date: 1967-11-27
Filing date: 1968-11-26
Publication date: 1970-12-01
Anticipated expiration: 1987-12-01
Also published as: DE6602774U; FR1599862A; GB1227618A; DE1614743B1

Description

Dec. 1, 1970 I I D S 3,544,941

THERMAL RELAY Filed Nov. 26. 1968 IN VE N 70/? orro [M /swa BY United States Patent U.S. Cl. 33738 12 Claims ABSTRACT OF THE DISCLOSURE A thermal relay with one or more operating coil phases. The actuating members associated with the coil phases are of bimetallic strips to compensate for dimensional variation due to thermal effects. Each operating phase has a movable sliding member cooperating with the actuating member. Electrical contracts are actuated through the sliding movable members in their path of motion. Each one of the sliding movable members is provided with a spring portion in the form of an arch terminating in a projection which is movable upon a sliding surface. This sliding surface lies upon a projection, in turn, of a retaining member in which the sliding movable members are slidable. A contact actuating link with a U-shaped portion is arranged relative to the sliding surface so that the U-shaped portion becomes contacted by the spring portion after sliding off the sliding surface.

BACKGROUND OF THE INVENTION The present invention resides in a thermal relay with one, two or more phases associated with actuating elements. These elements grip a slider Which actuates electrical operating contacts through motion along a predetermined path, depending upon the operating current.

Thermal relays of the preceding species are known in the art. These conventional relays, however, are exceptionally complex in design and construction, and are not reliable in operation.

Accordingly, it is an object of the present invention to avoid these disadvantageous features. This object of the present invention is achieved by providing that each movable member is constructed with a spring portion associated with a sliding surface along a path corresponding to the operating current. A movable element is arranged on the sliding surface so that the spring portion of each movable member strikes the electrical operating contact with this element after leaving the sliding surface.

An advantageous design of the present invention resides in the design of a spring portion of the movable member, so that this spring portion presses upon the movable element as a result of the force of the cool operating element during its return motion. This pressure exerted by the spring portion takes place until this spring portion reaches again its normal position upon the sliding surface, after sudden and sharp release from the movable element. Through this design, a considerable advantage is realized through the condition that the energy associated with the cooling bimetallic strip is used to return the operating elements of the relay to their normal or inoperative position. This design saves the use of springs or similar auxiliary means. Heretofore, relays have required such spring parts, and these had to be pre-stressed during the operation. Through this design of the relays, heretofore, the bimetallic strips were consequently subjected to considerable forces which caused them to become insensitive and operate with poor precision.

ice

In a simplified construction of the present invention, the movable members operate parallel to each other and are all movable within a slide. In this design, it is of advantage to provide the sliding surface in the form of a projection of the slide. A further embodiment and design of the relay of the present invention, the slide is provided with a recess into which the outer free end of a displaceable tongue expands for the purpose of regulating the setable region. In this manner, it is possible to achieve through simple construction, regulation of the setable region. Thus, the slide and thereby the sliding surface of the projection of the slide become shifted or moved, and the operation takes place earlier or later, as desired.

A simplified construction and a particularly advantageous design results when the movable element is in the formof a U-shaped head member which grasps with play, the portion containing the sliding surface. In conjunction with this, it is advantageous that the spring portion of each movable member has an arch terminating in a projection parallel to the sliding surface, and including a reinforcing or supporting member.

In some cases, it is advantageous to construct the thermal relay with provision for space compensation. This may be achieved in a very simple manner from the constructional viewpoint, by providing that the operating elements as well as the tongue are of bimetallic strips which serve to compensate for spatial or dimensional variations.

In order to overcome insulating problems, the present invention provides further that the movable members and/or their spring portions of the relay are made of insulating material. At the same time, the design can be such that the springs are of metallic substance covered with insulating material.

In the aforementioned embodiment of the present invention, the forces of the associated operational elements of bimetallic substance, are applied only in conjunction with the operation. Thus, these forces are not required to stress any springs or similar such elements during the operational process, As a result of this condition of the design of the present invention, more than a single contact may be actuated by the movable element. For example, it is possible to actuate an interrupter contact for the protective coil and aside from this, a circuit closure contact such as a signal contact. These contacts may be actuated at the same instant of time.

SUMMARY OF THE INVENTION A thermal relay with one or more operating coil phases. Each operating coil phase has an actuating member cooperating with a slidable or movable member. An electrical signal contact becomes actuated through the sliding or movable memberin the path of motion of the latter. Each sliding or movable member is provided with a spring portion terminating in a projection slidable upon a surface which projects from a slide. The slide with its sliding surface is positioned as a function of the current through the operating coil. A movable U-shaped member actuates the electrical contact when the spring portion slides off the sliding surface on the slide.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

3 BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plane view of the thermal relay, in accordance with the present invention, when in the normal inoperative state;

FIG. 2 is a sectional view taken along the line 11-11 in FIG. 1; and

FIG. 3 is a partial operational view of a portion of the relay in FIG. 1, when in the operated state.

DESCRIPTION OF THE PREFERRED EMBODIMENT In referring to the drawing, the diagrams are to be considered from the purely schematic viewpoint in determining the novel construction and features of the thermal relay, in accordance with the present invention. Thus, the individual relay parts are shown only in schematic form for the purpose of permitting a clearer understanding. It will be apparent that when producing a miniaturized design or a simplified design, the relevant steps may be taken with regard to the construction of the parts.

In the embodiment schematically shown, a base plate 1 is provided with a simple and fixed guide block 2. A slide 3 is held by the guide block and is movable to the left or right in relation to the fixed guide block. The slide 3 has three

longitudinal channels

30, 3b and 3c in which movable rods or

bars

4, 5 and 6 are lengthwise retained. Through

openings

7a, 8a and 9a, the individual movable rods or bars are contacted with actuating elements in the form of bimetallic strips 7, 8 and 9, respectively. These bimetallic strips are provided with

coils

10, 11 and 12 corresponding to the desired phases. A spring 13 lies at the right end of the slide 3 and abuts the plate 14.

At the left end of the slide 3 is a

projection

3d and 3e. The projection portion 3e has at its upper side a gliding or sliding surface 3f. Between the two projections lies a recess into which the foot 15c projects. This foot is part of a head portion to be described below. Each movable bar or

member

4, 5 or 6 is provided with a spring portion 4a in the form of an arch terminating in a projecting portion 4b Which is parallel to the gliding surface 3 The spring portion 4a, furthermore, is provided with a cross or incline supporting member 4c. The element 32 of the projection 3d of the slide has, for example, ane L-shape when viewed from the top. A U- shaped head member 15a with

feet

15b and 15c grasps the element 3e with play therebetween. The head portion 15a with

feet

15b and 15c are part of the movable member 15. The movable member 15 is vertically slidable within the guiding bears 16, and is pressed upward in the normal or inoperative state, by a spring 18. A connecting member 17, furthermore, connects the movable member 15 with a contact 19.

Connections

20 and 21 lead to the contact 19. Through the rod 22, one or more additional contacts may be actuated, in operation, as for example the contact 23 which may be used to advantage as a signal contact.

The region of the right end of the slide 3 is provided with a recessed portion 24. The outer free end of an adjustable tongue 25 reaches into the recessed portion 24. The tongue is secured to a rotatable setting arrangement 26 which may be moved or adjusted in either clockwise direction or counterclockwise direction. As a result of this possible displacement of the arrangement 26, the tongue 25 may be displaced either to the left or to the right within the limits designated by the broken lines in drawing. The tongue 25 serves the purpose of regulating the setting or adjustment region as to be described subsequently. When space compensation is desired, the tongue 25 as well as the operational members 7, 8 and 9 may be constructed of bimetallic strips.

All essential elements of the thermal relay, in accordance with the present invention, which are not directly operative with the contacts, are made of insulating material. This applies particularly to the slide 3, the movable rodes or bars 4, 5 and 6, and their

spring elements

4a, 4b and 4c. The aforementioned strip portions can also be constructed of spring metal with insulating covering.

In operation, when one phase of two phases as, for example, a

coils

10 and 12, has current exceeding that of the other phase, the bimetallic strips 7 and 8 become bent. This bending action is such that the upper ends of both strips are deflected to the left, and thereby move the

rods

4 and 5 to the left also. In this action, the projecting element 4b slides to the left on the entire gliding or sliding surface 3 on the portion 3e associated with the projection 3d of the slide. The projecting element 4b moves to the left, in this manner, until its edge reaches the left upper edge of the sliding surface 3 At this instant the arch 4a strikes downward with its projection 4b and reinforcing member 40, as a result of the spring force inherent in the arch member 4a. In striking downward, in this manner, the

U-shaped head portions

15a, 15b and of the movable member 5 are contacted and moved against the action of the spring 18. Through the motion of the membor 17 moving downward with the movable member 15, the contact 19 becomes sharply opened, while the contact 23 becomes simultaneously closed as a result of the downward movement of the rod 22. During this operation, the bimetallic strip 9 retains the slide 3 in its original position, against the action of the spring 13.

After the bimetallic strips 7 and 8 have become cool again, the

movable members

4 and 5 return or retrace their path, with their spring portion 4a as well as the projection 4b. In this motion, the projection 4b slides or glides on the left upper edge of the sliding surface 3 until the projection 4b is again on top of the sliding surface 3 The operational states of the relay may be determined from a comparison of FIGS. 1 and 3.

During the last-aforementioned process in which the projection 4b slides again on top of the sliding surface 3]", the reinforcing or supporting c-ross member 4c bears steadily on the upper surface of the foot 150, and thereby retains the movable member 15 in its lower or depressed position. This condition prevails even though the projection 4b has left contact with the foot 15b. As a result of the construction of the arch 4a with its inherent spring force, the cross member 40 is associated with a pressure or force amplification. At the instant, however, when the projection 4b reaches over the sliding surface 3 the projection slides upon the sliding surface to the right and towards its original position. During this motion to the right of the projection 4b, the cross member 4c becomes sharply removed from the foot 150, and thereby allows the contact 19 to close again. The closure of the contact 19 results from the motion of the member 15 in the upward direction through the action of the spring 18. At the same time, the contact 23 is re-opened in view of the upward motion of the rod 22.

The same process prevails when also other phases or all three phases receive an excess of current.

It has been found in practice that when the phases are loaded unsymmetrically, rapid disconnection must take place, and the relay as described above, in accordance with the present invention, provides for this purpose. In this manner the thermal relay of the present invention provides for a simple configuration in which a dependable and sensitive differential protection is effectively achieved. With symmetrical or uniform loading of the phases, an increased load can result from the connecting electrical apparatus. The relay, in accordance with the present invention, takes this condition also into account in the following manner. When the loading is uniform in the

coils

10, 11 and 12, the bimetallic strips 7, 8 and 9 are essentially bent uniformly also. As a result the slide 3 can be moved somewhat to the left, through the action of the spring '13, until the element 25 is reached. With the motion of the slide 3, however, the projection 3:1 is also moved together with its portion 3e and the sliding surface 3]. The

left lower edge 4d of the arch 4a thereby passes over the left upper edge 3g of the sliding surface 3 but first at a later instant of time or at a higher current load of the phases. Through this action, the procedure operation was carried out as described above.

Through the presence of the tongue 25, the thermal relay, in accordance with the present invention, may be regulated over a wide setable region to take into account various factors. The upper end of the tongue 25 extends into the recess 24 with a substantial amount of play between these two parts. If the tongue is rotated in the clockwise direction, the upper end of the tongue becomes displaced somewhat to the right. With a predetermined bending of the bimetallic strips, it will be understood that the right edge of the recess 24 will strike or come in contact with the upper end of the tongue 25. When the upper end of the tongue thus strikes or abuts against the inner wall of the recess 24, the slide 3 is held stationary, and accordingly the action described above occurs correspondingly in time. If, on the other hand, the tongue 25 is rotated or displaced in the counterclockwise direction, the upper end of the tongue is moved or displaced to the left. The slide is thereby first held stationary by the tongue after a larger sliding motion to the left. Thus, the

movable members

4, 5 and 6 can first incur a relative motion With respect to the slide, either individually or together, when a corresponding larger current prevails, as described above for the current loading. When, in addition, space compensation is desired for the thermal relay, the tongue 25 may be constructed of bimetallic strips. With this construction the bimetallatic strip is subjected to the same variation as the bimetallic strips 7, 8 and 9, which result from variations in the temperature of the space. By resorting to this type of construction, space temperature compensation is achieved.

The present invention is not limited to the embodiment described in the drawing. The present invention may also be extended and used in conjunction with the principles that have hereinbefore described, so that the present intion may be adapted to different factors and conditions, as well as the associated constructions.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions diifering from the types described above.

While the invention has been illustrated and described as embodied in thermal relays, it is not intended to be limited to the details shown, since various modifications and structural changes may be made Without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A thermal relay comprising, in combination, at least one operating coil means; actuating means in proximity of said operating coil means and operatively coupled with said coil means so that heat transmitted by said coil means impinges uponsaid actuating means; sliding means displaced by said actuating means; spring means secured to said sliding means; sliding surface means displaceable relative to said spring means, said spring means being movable on said sliding surface means; displacement means for displacing said sliding surface means; a movable member arranged relative to said sliding surface means and displaced by said spring means after sliding off said sliding surface means; and contact means actuated by said movable member when displaced by said spring means secured to said sliding means.

2. The thermal relay as defined in claim 1 wherein said sliding means comprises a plurality of slidable movable members arranged parallel to each other.

3. The thermal relay as defined in claim 2 including a slide retaining member for retaining said slidably movable members, said slidably movable members being slidable within said slide retaining member.

4. The thermal relay as defined in claim 1 wherein said movable member has a U-shaped portion lying opposite said spring means.

5. The thermal relay as defined in claim 1 wherein said spring means comprises an arch-shaped portion with a projecting portion parallel to said sliding surface means; and a supporting portion secured to said arch portion.

6. The thermal relay as defined in claim 1 wherein said sliding means and said spring means are of electrically insulating substance.

7. The thermal relay as defined in claim 1 wherein said spring means is of electrically insulating substance.

8. The thermal relay as defined in claim 1 including electrically insulating means on said spring means.

9. The thermal relay as defined in claim 1 wherein said contact means comprises a plurality of electrical contacts.

10. A thermal relay comprising, in combination, at least one operating coil means; actuating means in proximity of said operating coil means and operatively coupled with said coil means so that heat transmitted by said coil means impinges upon said actuating means; sliding means displaced by said actuating means; a slide retaining member for retaining said sliding means; spring means on said sliding means; sliding surface means displaceable relative to said spring means, said spring means being movable on said sliding surface means; a movable member arranged relative to said sliding surface means and displaced by said spring means after sliding off said sliding surface means; and contact means actuated by said movable member when displaced by said spring means on said sliding means, said sliding surface means comprising a projecting portion on said slide retaining member.

11. A thermal relay comprising, in combination, at least one operating coil means; actuating means in proximity of said operating coil means and operatively coupled with said coil means so that heat transmitted by said coil means impinges upon said actuating means; sliding means displaced by said actuating means; spring means on said sliding means; sliding surface means displaceable relative to said spring means, said spring means being movable on said sliding surface means; a movable member arranged relative to said sliding surface means and displaced by said spring means after sliding off said sliding surface means; contact means actuated by said movable member when displaced by said spring means secured to said sliding means, said sliding means comprising a plurality of slidable movable members arranged parallel to each other; a slide retaining member for retaining said slidably movable members, said slidably movable members being slidable within said slide retaining member; and a displaceable tongue member having a free end extending into a recess of said slide retaining member.

12. The thermal relay as defined in claim 11 wherein said actuating means and said tongue member comprise bimetallic strips for compensating against dimensional changes resulting from thermal effects.

References Cited UNITED STATES PATENTS 2,199,477 5/1940 Besag 337--47X FOREIGN PATENTS 994,436 6/ 1965 Great Birtain 337-49 625,121 1/1936 Germany 337335 OTHER REFERENCES German printed application DAS 1,128,535, April 1962, Carlsson et al., 337-3 8.

BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner U.S. Cl. X.R. 33749, 335