GB2280063A - Relay for the switching of high currents - Google Patents

Abstract

A relay for the switching of high currents has a contact element (6) for opening or closing current flow between first and second connectors (3, 4). One end of the contact element (6) is conductively connected to the second connector (4). An actuating element (16, 19, 20) is connected to the contact element (6) and by means of a coil 12 is arranged to move the contact element (6) into one of two end positions. The contact element (6) is configured as a leaf spring and at least one section (9a, 9c) thereof protrudes substantially perpendicularly from the plane of the leaf spring (6). In this manner, the resilient properties of the leaf spring (6) are improved without necessitating a tapering in the cross section of the leaf spring (6). A pressured contact is, despite loss of material on the surfaces of the contact heads (5, 8) effected by means of an additional resilient spring element (11). <IMAGE>

Description

RELAY FOR THE SWITCHING OF HIGH CURRENT STRENGTHS The present invention relates to a relay for switching of high current strengths.

A relay know in the art has a contact element for closing or opening the circuit between a first and a second connection whose one end is conductively connected to the first connection and via whose other flexible end the circuit is, in a first end position of the contact element, closed or, in a second end position of the contact element, open, with at least one activation element connected to the contact element and with one magnetic field with changeable polarity which, by means of the at least one activation element, moves the contact element into one of its two end positions.

In such a known relay, solid pieces of conducting material with large cross sections are utilized to conduct large current strengths in the range of 100 A or more.

When such a solid element is utilized as the contact element in a relay, the contact element must furthermore exhibit good elastic properties which, however, can, if at all, be only poorly realized with solid pieces. For this reason the cross section of the solid element is machinedaway along a longitudinal section in such a fashion that, due to this cross-sectional tapering of the solid piece, the required elasticity is achieved in its bending direction. This machining-away can be effected on one or both sides of the solid element. The cross-sectional tapering effects the required elasticity, however, increases the conductive resistance to the current. In particular with current strengths in the vicinity of 100 A and above this leads to an undesired increased resistance of the relay and to an inappropriate if not dangerous heating of the tapered section of the solid element.

It is an object of the present invention to further improve a relay such that better elastic properties of the contact element are achieved without requiring a tapering in cross section.

According to a first aspect of the invention there is provided a relay for switching electrical current comprising an elongate contact element which is fixed at one end, and electrically actuable means arranged to cause movement of the other end of said contact element between open and closed positions thereof, wherein said contact element is an elongate member of resilient material and has at least one section thereof which protrudes substantially perpendicularly to the longitudinal extent of the contact element.

The outwardly protruding section of the contact element can exhibit any geometric structure, for example, an angular shape or polygon structure. It is preferred, however, if the protruding section is curved.

The invention also extends to a relay for the switching of high current strengths comprising a contact element for opening or closing current flow between a first and a second connector, one end of the contact element being conductively connected to the first connector, wherein, via the resilient other end of the contact element current flow is, in a first end position of the contact element, closed or, in a second end position of the contact element, interrupted, the relay further comprising at least one activation element coupled to the contact element and with a magnetic field, whose polarity can be changed, and arranged to move the contact element into one of its two end positions, and wherein the contact element is configured as a leaf spring with at least one section which protrudes substantially perpendicularly out of the plane of the leaf spring.

This measure has the advantage that the good elastic properties of a leaf spring are not associated with loss of cross section. In this fashion it is easy to switch currents in the region of 100 A or more via the contact element without causing excessive local heating. By means of the inventive longitudinal section of the leaf spring which protrudes out of the plane of the spring, the elasticity of the leaf spring is increased, since the protruding surface of this projecting section is either pushed together or pulled apart leading to an increase in the elasticity of a leaf spring deflected out of its rest position.

A particularly preferred embodiment has the contact element being configured as a plurality of leaf springs which are arrangeable on top cf each other. If the cross-sectional area of the contact element is to be increased, an appropriate number of thin individual leaf springs are arranged on top of each other as a result of which, on the one hand, the elasticity is improved compared to tat of a solid element and, on the other hand, any aesirable cross-sectional area can be realized through an appropriate stacking of thin leaf springs.

If at least the uppermost and the lowermost leaf springs of the contact element exhibit a curved section which extends outwardly perpendicular to the plane of the leaf spring, the elasticity of the contact element is further increased by these two-sided curved sections. In order to individually adjust the elasticity, in a further embodiment of the invention, the curved sections of at least the uppermost and lowermost leaf springs are displaced relative to each other.

By way of example, one of the two leaf springs can exhibit a longitudinal slot at its anchored end so that the leaf spring, along with its curved section, can be displaced in a longitudinal direction within the slot.

In a further particularly preferred embodiment, an elastic element is provided for in the housing whose one end is fixed to the housing and whose other end supports the pivoting motion of the contact element at least in one direction, preferentially in the direction of the position of the contact element closing the circuit. With the large currents mentioned, there is a loss of material over time on the contacts to be opened or to be closed due to heat development and the production of sparks, so-called electrode erosion. For this reason it is useful for the contacts to exhibit a certain electrode erosion reserve amount. The elastic element advantageously provides for a certain amount of pressure between both contacts even with gradual contact erosion in that it exercises an additional force on one of the two contacts.

In order for the pivoting motion of the contact element not to be restricted by the spring element, both elements are configured in such a fashion that the force exercised on the contact element by the spring element in the direction towards its closing position is smaller than the force caused by the bending of the contact element. Preferentially the spring element is likewise configured as a leaf spring so that, in addition to simplicity of production, a simple adjustment of the desired spring force is possible through alignment of its anchoring to the housing in its longitudinal direction.

Further advantages can be extracted from the description and the accompanying drawing. The above mentioned features and those to be described below in accordance with the invention can be utilized individually or collectively in arbitrary combination. The embodiments shown are not to be considered as exhaustive enumeration rather have exemplary character only.

The invention is represented in the drawing and will be more closely described in connection with the embodiments.

Figure 1 shows an inner view of the relay in accordance with the invention with the cover removed in the position in which the contact element closes the circuit between two connectors; Figure 2 shows a view corresponding to that of figure 1 with the contact element interrupting the circuit between two connectors; Figure 3a shows an enlarged view III of figure 1; Figure 3b shows a view corresponding to that of figure 3a in another embodiment of the enlargement; and Figure 4 shows a side view corresponding to figure 1 of the relay in accordance with the invention in the direction of the arrow IV of figure 1.

In the embodiment of the drawing, 1 indicates a housing which is essentially box-shaped and which can be closed by a removable cover 2.

In figures 1 and 2 two contact arms 3, 4 extend perpendicularly outward from the upper side wall. These two contact arms 3, 4 form two electrical connections between which a circuit can be closed or opened by means of the inventive relay. Both contact arms 3, 4 extend into the housing 1, whereby the legs 3', 4' of the contact arms 3, 4, angled at a right angle within the housing 1, face in the same direction (towards the right in figures 1 and 2) and whereby the angled leg 4' in the housing 1 of the second contact arm 4 is displaced relative to the angled leg 3' of the first contact arm 3 and projects further into the inside of the housing 1.

A contact head 5 is attached to the inner housing leg 3' of the first contact arm 3 in a fashion not shown. This attachment can, for example, be effected by welding or by riveting of the contact head 5 to the leg 3' of the first contact arm 3. The ends of three stacked leaf springs 6a, 6b, 6c are securely attached to the legs 4' of the second contact arm z within the housing, whereby the attachment is effected by means of a weldment or a rivet connection 7. A heavily alloyed copper alloy is preferred as a material for the leaf spring. The leaf springs 6a, 6b, 6c extend from the second contact arm 4 sufficiently far in the direction of the first contact arm 3 that the contact head 8 arranged on the other end of the leaf spring 6 which is essentially identical to the contact head 5 of the first contact arm 3, exhibits plane-parallel contact with the contact head 8.

The upper and lower leaf springs 6a, 6c exhibit, in a middle section along their length, a curved section 9a, 9c which extends perpendicular to the plane of the leaf spring 6. The leaf springs 6 lie in a horizontal plane in the relaxed state shown in figure 1.

An activation head 10, arranged on the side of the leaf spring 6 opposite to the contact head 8, has an outer surface facing away from the leaf springs 6 and is convex in shape. The entire thickness of the contact head 8 and the activation head can 10 corresponds to the displacement of the two mutually displaced legs 3', 4' of the contact arms 3, 4 which face into the housing 1.

An activation spring 11, configured as a leaf spring, is secured to the housing 1 on one side. In its middle section the activation spring 11 tangentially engages the activation head 10, whereby through a displacement of the position of the activation spring 11 and of the surface in contact with the activation spring 11, a certain biasing of the activation spring 11 is er efftB. This biasing urges the contact head 8 of the leaf spring 5 against the contact head 5 o the first contact arm 3.

A coil 12 is also arranged in the housing ", with two opposite yoke legs loa 14b extending from its coil body 13 between which a large air gap is provided. In the embodiment described, the coil 12 exhibits a double winding so that it is possible to change the polarity of the magnetic field of the coil 12 by means of three electrical contacts 15a, 1Sb, 15c which extend outward from the housing 1. Alternatively, a coil with a single winding can be utilized with which only two connections are necessary. In figure 1 the magnetic field of the coil 12 is directed in such a fashion that the south pole is at the upper yoke leg 14a and the north pole of the magnetic field at the lower yoke leg 14b.

A rocker 16 is arranged in a pivotable fashion between both yoke legs 14a, 14b. The rocker 16 exhibits, for example, a core element 17 with a rectangular or round cross section on the two ends of which two base plates 18a, 18b are attached.

The core element 17, as viewed in the direction of the yoke legs 14a, 14b, is smaller than the separation between the yoke legs 14a, 14b, whereas the base plates 18a, 18b are larger. In this fashion the rocker 16 is captured between both yoke legs 14a, 14b of the coil 12. The core element 17 is configured as a permanent magnet with a magnetization direction perpendicular to the magnetic field of the coil 12. In the embodiment, left is the north pole and right is the south pole of the permanent magnet 17. With the polarity of the magnetic field shown in figure 1, the yoke legs 14a, 14b attempt to effectively straighten the permanent magnet 17 so that it pivots in a clockwise direction until the pivoting motion is limited by the base plates 18a, 18b.

An activation arm 19 is rigidly connected to the rocker 16 which, relative to the rocker 16, extends axially away from the coil 12 in a direction towards the first contact arm 3. The far end of the activation arm 19 is hinged to a translating member 20 in a manner not explicitly shown.

The activation arm 19 can, for example, engage a recess in the translating member 20.

The translating member 20 is seated such that it is translatable in the direction of the double arrow 21, whereby its upper end exhibits a shoulder 22 which extends above the leaf spring 6. The extended shoulder 22 of the translating member 20 does not yet interact with the leaf spring 6 in the position shown in figure 1. The far end of the activation spring 11 seats, in a manner not explicitly shown, in a section between the leaf spring 6 and the activation arm 19 and, also in a manner not explicitly shown, an indicator 23 which is likewise displaceable in the direction of the double arrow 21, adjusts its position in correspondence with the translating member 20.

Figure 2 shows the changed positions of the individual moving components of the relay in accordance with the invention when the polarity of the magnetic field of the coil 12 is changed. The permanent magnet 17 of the rocker 16 has aligned itself in accordance with the changed polarity of the magnetic field of the coil 12 so that the rocker 16 has exercised a pivoting motion in a counterclockwise direction, whereby the pivoting motion is limited by the base plates 18a, 18b. Along with the rocker 16, the activation arm 19 is correspondingly pivoted in a counterclockwise direction as a result of which, the translating member 20 moves downwardly. With this downward motion the shoulder 22 of the translating member 20 engages the leaf spring 6 from above and then, in the course of further motion, deflects same downwardly away from its relaxed horizontal state. This deflection causes the two contact heads 5, 8 to separate and thereby causes an opening in the circuit between the two contact arms 3, 4. By means of the downward motion of the translating member 20, the far end of the activation spring 11 and of the indicator 23 are deflected downwardly. The activation spring 11 is, in this fashion, sprung more strongly, however its force is smaller than the force effected by the translating member 20 on the leaf spring 6 so that the activation spring 11 does not prevent a pivoting of the leaf spring 6.

The purpose of the activation spring 11 is to urge, under a certain amount of pressure, the activation head 11 against the contact head 5 of the first contact arm 3 when the polarity of the magnetic field of the first coil 12 in figure 2 is changed. In particular at high currents of more that 100 A, a wearing away of the contact surfaces of the contact heads 5, 8 takes place due to electrode erosion so that the thicknesses of both contact heads 5, 8 are reduced over time. Due in particular to the biasing of the activation spring 11 at a certain pressure, the activation spring 11 effects a secure contact between both contact heads 5, 8 even in the event of gradual electrode erosion.

By means of the convex outer surface of the activation head 10 an optimal force transfer from the spring element 11 is guaranteed.

Figure 3a shows both curved sections 9a, 9c of the leaf spring 6a, 6c when it is deflected downwardly out of its rest position 24. The two curved protruding surfaces 25a, 25b of the upper leaf spring 6a are thereby pulled apart, whereas the two curved protruding surfaces 26a, 26b of the lower leaf spring 6c are pushed together. This displacement of the curved protruding surfaces 25a, 25b, 2Ga, 26b by several hundredths of a millimeter effects an upward torque without thereby having the cross-section of the leaf springs 6a, 6c, in their curved sections 9a, 9c, being changed relative to the non-deflected position. The middle leaf spring 6b is configured as a conventional leaf spring.

Fig. 3b shows an embodiment in which the uppermost leaf spring 6a and the lowermost leaf spring 6c are displaced relative to each other, thus that the curved sections 9a, 9c are displaced relative to each other. The intermediate leaf spring 6b is a usual leaf spring without curved section.

As particularly evident from figures 1 and 2, a surface 27 is graded on the housing 1 in such a fashion that, for example, it can accept a microswitch fixed to the housing 1 at attachment locations 28a, 28b. In addition, support struts 29 are provided in order to increase the stability of the housing 1.

Figure 4 shows a side view of the housing 1, whereby in addition to the electrical connection of the contact arms 3, 4 and the coil 15a the position of the translating member 20, that is to say of the relay indicator 23, is viewable from the outside. The relay can also be activated manually by means of the indicator 23 if a user moves the indicator 23 and thereby the translating member 20 in the direction of the double arrow 21 from the outside. In this fashion the leaf springs 6 forming the contact element of the relay can be ...anually adjusted to both of their end positions in which the circuit flow between the two contact arms 3, 4 is closed or opened.

The invent ion concerns a relay for the switching of high currents with a contact element 6, for opening or closing current flow between a first and a second connector 3, a, whose one end is conductively connected to the first connector 4 and, via its resilient other end, the current can be closed in a first end position of the contact element 6 or be interrupted in a second end position of the contact element 6, with a least one activation element 16, 19, 20 connected to the contact element 6 and with a magnetic field, whose polarity can be changed, which by means of the at least one activation element 16, 19, 20 moves the contact element 6 into one of its two end positions, whereby the contact element 6 is configured as a leaf spring with at least one section 9 which protrudes out perpendicularly from the plane of the leaf spring 6. In this fashion, the resilient properties of the leaf spring 6 are improved without necessitating a tapering in the cross section of the leaf spring 6. A pressured contact is, despite loss of material on the surfaces of the contact heads 5, 8, effected by means of an additional resilient spring element 11.

Claims (11)

1. A relay for switching electrical current comprising an elongate contact element which is fixed at one end, and electrically actuable means arranged to cause movement of the other end of said contact element between open and closed positions thereof, wherein said contact element is an elongate member of resilient material and has at least one section thereof which protrudes substantially perpendicularly to the longitudinal extent of the contact element.

2. A relay for the switching of high current strengths comprising a contact element for opening or closing current flow between a first and a second connector, one end of the contact element being conductively connected to the first connector, wherein, via the resilient other end of the contact element current flow is, in a first end position of the contact element, closed or, in a second end position of the contact element, interrupted, the relay further comprising at least one activation element coupled to the contact element and with a magnetic field, whose polarity can be changed, and arranged to move the contact element into one of its two end positions, and wherein the contact element is configured as a leaf spring with at least one section which protrudes substantially perpendicularly out of the plane of the leaf spring.

3. A relay as claimed in Claim 1, wherein the at least one section protruding out of the plane of the leaf spring is curved.

4. A relay as claimed in Claim 2 or Claim 3, wherein the contact element is configured as a plurality of superimposed spring leaf springs.

5. A relay as claimed in Claim 4, wherein at least the uppermost and the lowermost leaf springs of the contact element exhibit a curved section which extends substantially perpendicularly to the plane of the leaf spring in an outward direction.

6. A relay as claimed in Claim 5, wherein the curved section of at least the uppermost and the lowermost leaf spring are arranged displaced with respect to each other.

7. A relay as claimed in any of the preceding claims, wherein a resilient element is provided for whose one end is fixed to the housing and whose other end supports the pivotal motion of the contact element in at least one direction.

8. A relay as claimed in Claim 7, wherein the resilient element supports the contact element in the direction closing the circuit.

9. A relay as claimed in Claim 7 or Claim 8, wherein the force exercised by the resilient element on the contact element in the direction towards its closed position is smaller than the force caused by the bending of the contact element.

10. A relay as claimed in any of Claims 7 to 9, wherein the resilient element is configured as a leaf spring.

11. A relay substantially as hereinbefore described with reference to the accompanying drawings.