EP0110758A1 - Thermal relay - Google Patents

Abstract

1. A thermal relay comprising : a first case (2") in which are disposed current monitoring bi-metal strips (3 to 5) adapted to communicate their movements to a link (9) and a second removable case (2') associated with the first one so that the link may communicate to a normally closed safety switch (45), placed inside, a work position in which the switch is open, characterized in that this switch (45), a movement transmission device (77) and a thermal compensation device (19) are disposed in said second case (2') having a small width ("q") measured in the direction of movement of the link (9) and having on several faces (80, 61, 64, 110) access windows (85, 84, 83, 109, 116) which are closed by dividing walls (72, 63, 86, 76) belonging to the first case (2").

Description

The invention relates to a thermal relay comprising a first housing in which are arranged current monitoring bimetals capable of communicating their movements to a strip and a second removable housing associated with the first so that the strip can communicate with a switch normally closed safety switch and placed inside a working position for which this switch is open. These relays are widely used in electrical engineering to protect motors in combination with contactors placed between them and the electrical supply network.

When these thermal relays consist of two detachable sub-assemblies, namely a first housing containing bimetallic strips and a second housing containing a safety switch, it is very easy to assemble the same switch housings with different bimetallic housings according to the power of the motor for which the relay is intended.

Such an assembly is moreover all the easier as the power of the motors is greater, because the dimensions of the housings at the same time become larger and therefore facilitate the respective arrangements of the various mechanical elements which are placed between the strip transmitting the deformations of bimetallic strips and the safety switch.

Difficulties appear on the other hand when it is desired to give these thermal relays a smaller footprint to adapt their dimensions to those of the modern contactors with which they must associate, and whose volume is today close to a hundred cubic centimeters for motor powers on the order of two to three kilowatts.

These difficulties are essentially constituted by the low accessibility which one encounters when the housings are of "small dimensions, by the relative importance which take the usual manufacturing tolerances when the dimensions of associated parts become smaller, and by the possibilities of 'heat exchanges between the current monitoring bimetallic strips and a temperature compensation bimetallic strip.

If this latter difficulty is largely avoided by the use of a monitoring bimetal box which is separate from the switch box where the compensation bimetal is housed, improving the overall dimensions and that of accessibility. requires taking measures that are compatible with proper operation, protection against external agents and good electrical insulation.

The invention therefore proposes to provide a thermal relay in which two detachable housings are used, and where measures will be taken so that the overall dimensions are reduced to an order of magnitude close to or less than that of the associated contactor, while maintaining accessibility compatible with series mounting, excellent cooperation between the moving parts of the device, electrical insulation corresponding to that of the contactor and effective protection against the environment.

There are already known, for example from American patent 3315054, thermal relays whose general constitution responds to that mentioned above, but where the arrangement of the moving parts does not lend itself to a significant reduction in dimensions, while the presence of only one window for the introduction of these parts makes it difficult to mount them inside the switch housing. In addition, it can be noted that all of the adjustment members of the thermal relay are not presented on the same upper face, which indirectly increases the overall dimensions insofar as a space, necessary for their access, must be left empty between the relay. and any neighboring devices.

According to the invention, the targeted result is achieved thanks to the fact that this switch, the movement transmission device, the thermal compensation device are arranged in a second housing having a small width measured in the direction of movement of the strip and having on several faces of the access windows which are closed off by partitions belonging to the first housing.

• la figure la représente un relais thermique dans lequel les différentes fonctions de l'appareil ainsi que leur mode de coopération ont été indiqués de façon schématique ;
• la figure lb illustre un mode de réalisation du relais thermique selon la figure la, dans lequel les diverses pièces ont été représentées de façon simplifiée dans un seul et même plan pour rendre plus clair le fonctionnement ;
• la figure 2a représente, en coupe par un plan médian PP', le boîtier amovible contenant l'interrupteur, les pièces mobiles ayant été enlevées pour mieux montrer la disposition respective de certains volumes ;
• la figure 2b montre une vue extérieure du boîtier d'interrupteur observé depuis l'avant de la figure 2a ;
• la figure 2c montre une vue extérieure du boîtier d'interrupteur observé depuis l'arrière de la figure 2a ; .
• la figure 3 illustre une vue en coupe du boîtier d'interrupteur qui est analogue à celle de la figure 2a, mais dans laquelle les pièces mobiles ont été représentées ;
• la figure 4 montre une vue de côté du boîtier de la figuré 3 coupé par le plan SS' ;
• la figure 5 montre une vue de côté du boîtier de la figure 3 coupé par le plan brisé QQ' ;
• la figure 6 représente une vue en perspective simplifiée des deux boîtiers du relais thermique une fois assemblés
• la figure 7 montre un schéma de branchement du relais thermique avec un moteur et un contacteur ;
• la figure 8a illustre une vue de côté du boîtier du relais thermique dans lequel sont disposées les bilames de surveillance de courant ; et,
• la figure 8b illustre une vue de dessus du même boîtier de relais thermique que celui de la figure 8a.

The invention and the accompanying measures will be better understood on reading the description below and on examining the twelve appended figures, among which:

• FIG. 1a represents a thermal relay in which the various functions of the apparatus as well as their mode of cooperation have been indicated diagrammatically;
• FIG. 1B illustrates an embodiment of the thermal relay according to FIG. 1a, in which the various parts have been represented in a simplified manner in a single and same plane to make operation clearer;
• Figure 2a shows, in section through a median plane PP ', the removable housing containing the switch, the moving parts having been removed to better show the respective arrangement of certain volumes;
• Figure 2b shows an exterior view of the switch housing seen from the front of Figure 2a;
• Figure 2c shows an exterior view of the switch housing seen from the rear of Figure 2a; .
• Figure 3 illustrates a sectional view of the switch housing which is similar to that of Figure 2a, but in which the moving parts have been shown;
• Figure 4 shows a side view of the housing of Figure 3 cut by the plane SS ';
• Figure 5 shows a side view of the housing of Figure 3 cut by the broken plane QQ ';
• Figure 6 shows a simplified perspective view of the two thermal relay boxes once assembled
• FIG. 7 shows a diagram of the connection of the thermal relay with a motor and a contactor;
• FIG. 8a illustrates a side view of the thermal relay box in which the current monitoring bimetals are arranged; and,
• Figure 8b illustrates a top view of the same thermal relay box as that of Figure 8a.

A thermal relay 1 according to the invention performs a protection function of a motor M in the context of a circuit visible in FIG. 7 and using a contactor 90 having an electromagnet coil 93 which controls the closing and opening of power switches 96, 97, 98 to establish a connection with the RST network. An auxiliary contact 95 is also actuated by this electromagnet. The thermal relay has input power terminals 100, 101, 102 connected to corresponding terminals the contactor and output power terminals 103, 104, 105, connected to the motor, and between which are arranged heaters 3 ', 4', 5 'which produce the deformation of bimetallic strips 3, 4, 5 placed in their vicinity; these heaters can also be part of bimetallic strips. A safety switch 57, normally closed, is opened by the movement of the bimetallic strips when they reach a determined temperature, this temperature being reached at the end of a time interval which is a function of their previous temperature, of the ambient temperature and the intensity of the current flowing in the heaters.

In the circuit, shown in operation, the coil of the electromagnet 93 is connected in series with the safety switch 57 and with a commissioning switch 94 between the + and - poles of a source and at l using terminals 92, 91, 70, 71. The auxiliary contact 95 which is connected in parallel to the switch 94 excites the electromagnet when the switch 94 ceases to be actuated.

When, as a result of abnormal conditions such as an overloaded motor, the bimetallic strips reach a too high temperature, the switch 57 opens and the electromagnet, for lack of excitation, opens the power switches 96, 97 , 98 to interrupt the motor supply.

The operation of the thermal relay 1, as well as the choice of certain operating modes, the adjustment of the nominal current of the motor, and the adjustment of the relay in the factory are obtained using the parts visible in FIG. 1b, where we note that this relay, which is externally in the form of an envelope 2 uses two boxes 2 'and 2 "which are associated.

The box 2 "contains the bimetallic strips 3, 4, 5, their heaters, their corresponding terminals 100, 101, 102, 103, 104, 105 and a motion transmission strip 9 which receives the deformations of these bimetallic strips. On pushers 6 , 7, 8.

The 'box 2' contains the safety switch 57, the corresponding terminals 70, 71, as well as a set of members which will be described below.

One end 10 of the strip which enters the housing 2 'through an opening 12 after passing through 11 of the housing 2 ", is placed opposite an end 13 belonging to a lever 14 articulated at point 15 on the end 17' of a lever 17, one opposite end 17 "of which is pivoted on point 18 of the housing 2 '.

These two levers 14 and 17 constitute a movement transmission mechanism 77 which transmits the movement of the strip to a device with neutral passage 30.

However, the transmission of this movement requires that a point 24 of the lever 14 meet a fulcrum 23 belonging to a device for compensating the ambient temperature 19. The fulcrum 23 is represented by the end of a bimetallic strip 22 which is fixed on a frame 20 pivoting around a pivot 21.

A spring 25, placed between the frame 20 on which it is preferably fixed, and a point 26 of the housing 2 ', communicates to this frame a clockwise torque which applies a fixed end 27' of the bimetallic strip 22 against a cam 28 belonging to an intensity adjustment device 65 further comprising an adjustment member 29 linked to the cam and moves. erecting next to a scale of intensities 62.

The neutral passage device 30 comprises a rocking lever 31 which can oscillate around a pivot 32 between a stable rest position R, where a first bearing 59 placed in a region 33 is supported on a stop 58 of the housing 2 ', and one of two working positions T1 or T ₂ , the production and properties of which will be specified below.

A spring 34, which is stretched between a first attachment point 34 'of the lever 31 and a second attachment point 34 "placed on one end 16 of the lever 14 provides the neutral effect when the axis 34', 34 "of the spring passes through the axis of the pivot 32.

A second bearing 35 of the region 33 can come to bear under the effect of the spring 34 and for each of the positions T ₁

or T ₂ against a stop represented by the end 37 of a device for choosing an operating mode 36. This device is for example constituted by a cylindrical rod 38 which can slide and rotate in an opening 39 of the housing 2 'so placing a stud 43 of the housing 2 'in one of the ends of a groove 42 circulating axially and tangentially to the surface of the part 38. The latter is further subjected to the action of a return spring 41, which gives the end 37 a position M while a position A can be given to it by a push and a rotation exerted by the user on a head 40 of this part 38.

The lever 31 also has a hammer 44 which for each of the positions T ₁ or T ₂ will separate the movable and fixed contacts 48 respectively 49 of the safety switch 57. For this purpose, the hammer 44 is placed opposite a end 46 'of a lever 46, which carries the movable contact 48 and of which another end 46 "is pivoted at a point 47 of the housing 2'. As will be justified later, the lever 46 and the contacts 48, 49 constitute a variable resistive torque switch marked with 45. The lever 46 is in fact integral with a first end 50 "of a tension spring 50 having a second end 50 'fixed on a movable portion 51 of a device for adjusting position 78. When (in an operating mode for which the end 37 has received a position A) the movements of the bimetallic strips 3, 4, 5 are communicated to the strip 9, the transmission device 77 is pushed to the left and meets the end 23 of the bimetallic strip 22 after av have completed a race D; the tilting of the lever 14 around the point 24 produces an alignment of the points 34 ′, 32 and 34 ″ which immediately causes a sudden tilting of the lever 31 clockwise, which causes the opening of the switch 57 due percussion of the lever 46 by the hammer 44.

The adjustment device comprises an elastically deformable U-shaped part 53 having a fixed branch 55 secured to the 2 "housing and a movable branch 52 which carries the portion

mobile 51, the position of the latter being adjustable using an adjustment screw 54 which is screwed into the branch 52 and which is supported on the branch 55. Any movement of the mobile portion 51 modifies the torque exerted by the spring 50 on the lever 46.

The purpose of this adjustment device is to make that, when the stop 37 is in position A and the lever 31 in position T _{2 '} (which corresponds to an automatic operation of the closing of the switch), the torque exerted by the spring 50 on the lever 46 is slightly greater than the torque in the opposite direction exerted on the hammer 44 by the spring 34 to give the opening of the switch an unstable character; in this case as soon as the bimetallic strips cool, the lever 31 automatically returns to its rest position R for which the switch 57 is open.

When the bimetallic strips heat up sufficiently and the position M has been given, previously, at the end 37, a clockwise tilting of the lever 31, which is caused by the transmission device 77, ends when the span 35 meets this end 37.

The lever 31 which is then in position T ₁ opens the switch 57 and keeps this position stably due to the fact that the torque communicated by the spring 34 is now greater than the torque communicated by the spring 50. This modification of the values of the torque is due to a change in the inclination of the two springs.

A reset or reset of the thermal relay must then be carried out, after sufficient cooling of the bimetallic strips, to close the switch 57 manually. This resetting which can be carried out by a separate manual reset member, can also be carried out by an axial thrust, exerted to the left of FIG. 1b, on the button 40.

The thermal relay may also include a member 73, for effecting action on the lever 46, the voluntary opening of the switch 57 when a direction displacement B is communicated to it by the user.

The various actions and interactions of the organs which have just been described are found in the functional principle diagram of FIG. 1a where the same parts and devices are provided with the same references.

The physical embodiment of the thermal relay 1 uses a first housing 2 "where we find, in Figure 8a, the presence of neighboring cells 3a, 4a, 5a in each of which is placed a bimetallic strip 3, respectively 4, respectively 5, cooperating with the strip 9, movable in the plane RR '. Between two parallel walls 74, 76, placed laterally with respect to the cells, a bottom 72 and an external partition 86 is placed a housing 87 of small width "q" (about 11 mm) having a median plane PP 'parallel to the walls and perpendicular to RR'. The wall 76 is elastically deformable in the width direction "q".

As best seen in the top view of FIG. 8b, an external face 88 of the housing 2 "giving access to the cells is closed by a cover 89 which also closes a lateral entry 99 of the housing 87.

This insulating cover is crossed by the connection terminals 100, 101, 102, which are guided by guns 110a, 102a, 103a, and are placed opposite other connection terminals 103, 104, 105.

Two openings 106, respectively 107 are placed in the external partition 86 and situated substantially in the plane PP 'for a purpose defined later, see FIG. 8a.

The housing 87 is intended to receive, between two opposite parallel faces 63 and 108 of the partitions 74, 76, the second housing 2 'whose functions have been specified above.

Referring to Figure 2a, we see that the interior of the housing 2 ', which is here shown in section by the plane PP', is divided by an internal partition 75 into two separate volumes 66 respectively 67 which each communicate with a upper volume 68, these first two volumes being placed in a region L close to the plane RR 'in which the slide 9 moves.

The volume 66 communicates with the outside on the one hand, through a lower opening 85 of the bottom 80 of the housing 2 'and on the other part, by a side window 83 opening on the side of a bearing face 61, see also FIGS. 4 and 8b, called to cooperate with the face 63 of the wall 74.

The volume 67 communicates with the outside on the one hand, by a side window 109 opening on the side of the side face 110 and, on the other hand, with a window 84 which opens on the face 61 of the housing 2 'and which occupies the entire width of the volume 68 opposite which it is placed, see FIGS. 2a, 4 and 5. In addition, a window 116 opening onto the face 64 and opposite the window 83 authorizes the movements of the pivoting frame 20.

These windows and openings provide access to volumes 66, 67, 68 to allow the mounting of the parts described in Figure 1b.

The volume 66 mainly receives the organs of the transmission device 77 and of the thermal compensation device 19; the volume 67 receives mainly the organs of the switch device 45 and part of its adjustment device 78; finally, the volume 68 receives mainly the organs of the device passing through neutral 30 and those of the intensity adjustment device 65.

Referring to FIG. 2a and incidentally to FIGS. 3, 4 and 5, it can be seen that the axes of rotation or of pivoting of all the pivots or articulations of the levers used are substantially placed in the plane PP '; we recognize in XX 'the axis of the pivot 18, in YY' of the articulation 15, in TT 'the axis of the pivot 21, in VV' the axis of the pivot 47, and in ZZ 'the axis of the pivot 32.

The pivots 18, 32 and 47 are advantageously constituted by U-shaped notches 18a, 18b; 32a, 32b; 47a, 47b, which receive knives from the corresponding moving parts, see in particular FIG. 3, while the frame 20 is pivoted by means of its cheeks 20 'on pins 21a, 21b. This knife swivel mode provides very low friction and facilitates assembly, while the greater friction which appears on the pins 2la, 21b of axis TT 'are easily overcome by the torque exerted on the cam 28 at the time of adjustment. intensity manual. The axis YY 'of the joint 15 is also parallel to the other axes.

The part of the adjustment device 78. Of the switch 45, which is not placed in the volume 67, passes through the window 109 and protrudes outside the housing 2 ′ as well as a first conductive part 70a which is fixed on this housing and which carries the terminal 70 to connect the latter to the fixed contact 49 and that a second conductive part 7la which is integral with the _U- shaped part 53 and on which the contact lever 46 rests mobile 48 to connect it to terminal 71.

The part of the adjuster protruding from the housing 2 'is one end of the U-shaped part (53) on which the screw (54) is engaged, so that when the removable housing (2') is not yet associated with the housing (2 "), it is extremely easy to carry out the factory adjustment of the torque mentioned above.

The conductors 70a and 71a, which run parallel to the bottom 80 will pass through the openings 106 respectively 107 of the partition 86 at the time of the association of the two housings.

The intensity adjustment members 29, for choosing the operating mode M or A 40 and for voluntary opening 73 of the switch move along or around parallel axes II ', respectively JJ' respectively KK 'while crossing an upper wall l13 of the housing 2 'which is opposite the bottom 80 and carries an upper adjustment face 79 on which is for example disposed the intensity scale 62. These axes I, J, K are substantially placed in the plane PP '. When the box 2 'is engaged in direction F in the housing 87 of the box 2 ", a clearance 114 from the face 61 circulating parallel to the bottom 80 allows the end 10 of the strip 9, which is projecting, to present itself opposite the window 83 which therefore here also constitutes the opening 12 in FIG. 1b, see also FIGS. 3, 5 and 8b;

To make the association of the two boxes, the conductors 70a and .7la are previously deprived of the screws of their terminal 70 respectively 71.

The application of the bearing face 61 of the housing 2 'against the face 63 of the housing 2 "is obtained thanks to the elasticity of the wall 76 whose face 108 is applied to the face 64 of the housing 2', see arrow C in Figure 8a.

The cover 89, which is also put in place in the direction F, makes it possible to hold the box 2 ′ in place by pressing on the face 112 thereof (see FIG. 8b) by closing the housing 87 and closing the cells. 3a, 4a, 5a.

The reduction in the dimensions of the housing 2 ′ is mainly due to the respective arrangement of the parts in the different volumes and to a reduction in its walls by numerous windows and openings which also facilitate assembly.

The electrical isolation of the terminals 70, 71 which is established or completed during the association of the two housings by one or more partitions 86 of the bimetallic strip housing 2 "is also accompanied by environmental protection which is carried out. by other elements of this housing 2 "such as the walls 86, 76 and 74, the bottom 115 of the housing 87 and the cover 89 which close off all of the openings.

Claims (8)

1. Thermal relay comprising: A first housing in which are arranged current monitoring bimetals capable of communicating their movements to a strip and a second removable housing associated with the first so that the strip can communicate with a normally closed safety switch placed inside , a working position for which this switch is open, characterized in that this switch (45), a movement transmission device (77), and a thermal compensation device (19) are arranged in a second housing (2 ') having a narrow width "q" measured in the direction movement of the strip (9), and having on several faces (80, 61, 64, 110) access windows (85, 84, 83, 109, 116) which are closed by partitions (72, 63, 86, 76) belonging to the first housing (2 "). 2. Thermal relay according to claim 1, characterized in that the second housing (2 ') is applied against a face (63) of the first housing (2 ") and in direction C of the strip (9) by an elastic partition ( 76) of this first housing. 3. Thermal relay according to one of claims 1 or 2,
characterized in that the small width "q" is obtained by a parallel arrangement of the pivot axes (YY ', XX', TT ', ZZ', VV ') of levers (14, 17), (20, (30) and (46) which belong respectively to the transmission device (77), to the thermal compensation device (19), to a device with neutral shift (30) and to the switch (45), all these axes being substantially placed in a median plane PP 'of the second housing (2') which is prrpendicular to the direction of movement of the strip (9), and the pivots of axes XX ', _ZZ ' and VV 'implementing knives and notches . 4. Thermal relay according to one of claims 1 to 3,
characterized in that a first region (L) of the second housing (2 ') adjacent to the plane of movement RR' of the strip (9) comprises two neighboring volumes (66) and (67) in which the device is respectively disposed transmission (77) and the thermal compensation device (19) on the one hand, and the safety switch (45) on the other hand, the neutral passage device (30) being arranged in a third volume (68 ) which communicates with the other two and which is further from said travel plan. 5. Thermal relay according to claim 4, characterized in that an adjustment face (79) which limits the third volume (68) and which is opposite to said movement plane RR 'has three adjustment members (29, 40, 73 ) whose axes of movement (I, J, K) are substantially placed in the median plane PP 'and parallel to each other to adjust the trigger intensity respectively to choose one of two operating modes (A, M) of the resetting of the switch, respectively to carry out voluntary actuation of the safety switch (45). 6. Thermal relay according to one of claims 1 to 5,
characterized in that the safety switch (45, 57) is connected to two connection terminals (70, 71) which are substantially placed in the median plane PP 'on a connection face (110) perpendicular to this median plane and to the movement plane RR 'of the strip (9). 7. Thermal relay according to claim 6, characterized in that an adjustment screw (54) of the safety switch (45) is accessible on said outer face (110). 8. Thermal relay according to one of claims 1 to 7,
characterized in that the cells (3a, 4a, 5a) of the first housing (2 "), in which the bimetals (3, 4, 5) which actuate the slide (9) are arranged, are closed by a removable cover (89 ) which also forms an inlet (99) of a housing (87), of this first housing, capable of receiving the second housing (2 '). This housing being in particular limited by the elastic partition (76).

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