FR2536905A1 - 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

THERMAL RELAY.

  The invention relates to a thermal relay comprising a first box in which bimetallic strips are arranged.

  current monitoring able to communicate their displacements

  one ruler and a second removable housing associated with the first so that the ruler can communicate to a normally closed safety switch

  inside a working position for which this inter-

breaker is open.

  These relays are widely used in electro-technical to ensure the protection of motors in combination with contactors placed between them and the power supply network.

  When these thermal relays are made up of two sub-

  detachable assemblies, namely a first housing containing bimetals and a second housing containing a safety switch, it is very easy to assemble the same switch boxes with different bimetallic boxes according to the

  power of the motor-to which the relay is intended.

  Such an assembly is, moreover, all the easier as the

  engine power is more important because the dimensions of

  boxes become at the same time more important

  and thus facilitate the respective provisions of the

  mechanical elements that are placed between the ruler transmitting the bimetallic deformations and the switch

of security.

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  -2- Difficulties appear on the other hand when one wishes to give to these thermal relays a more

  reduced to fit their dimensions to those of

  modern engines with which they must associate, and whose volume is now close to one hundred cubic centimeters for engine powers of the order of two to three kilowatts. These difficulties are essentially constituted by the low accessibility encountered when the housings are small, the relative importance of the usual manufacturing tolerances when the dimensions of associated parts become smaller, and by the possibilities of thermal exchanges between the current monitoring bimetals and a bimetallic strip

temperature compensation.

  If the latter difficulty is largely discarded by the use of a bimetallic monitor box which is separate from the switch housing o, is housed the bimetallic compensating, the improvement of encumbrance and that of accessibility requires measures that are compatible with proper functioning, protection

  against external agents and good electrical isolation.

  The invention therefore proposes to provide a thermal relay

  in which two separate housings are used.

  and measures will be taken to ensure that the

  be reduced to an order of magnitude close to or less than

  than the associated contactor, while maintaining a

  accessibility compatible with a series connection, an ex-

  this cooperation between the moving parts of the device, an electrical isolation corresponding to that of the contactor

  and effective protection against the environment.

  We already know, for example by the US patent 3315054, thermal relays whose general constitution

  responds to the one mentioned above, but where

  the position of the moving parts does not lend itself to a significant reduction in dimensions, whereas the presence of a single window for the introduction of these parts makes it difficult to mount them inside the switch housing. not all the control elements of the thermal relay are presented on one and the same upper face, which indirectly increases the space requirement in that a space, necessary for their access, must be left empty between the relay and any neighboring devices . According to the invention the desired result is achieved thanks to the fact

  that this switch, the device for transmitting

  the heat compensation device are available.

  in a second housing having a small measured width

  in the direction of movement of the slider and

  sensing on several sides of the access windows that are

  closed by partitions belonging to the first casing.

  The invention and related measures will be better understood.

  taken from the description below and from

  the examination of the twelve appended figures among which: Figure la represents a thermal relay in which the various functions of the apparatus and their mode of cooperation have been indicated schematically; 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 FIG.

  only one and the same plan to make the func-

tioning;

  FIG. 2 a represents, in section, a median plane.

  PP ', the removable housing containing the switch,

  moving parts have been removed for better

  the respective disposition of certain volumes; Figure 2b shows an external view of the switch housing seen from the front of Figure 2a; Figure 2c shows an exterior view of the switch housing viewed from the rear of Figure 2a; FIG. 3 illustrates a sectional view of the switch housing which is similar to that of FIG.

  2a, but in which the moving parts were-

  represented; 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 ';

  FIG. 6 represents a simplified perspective view

  the two heat relay boxes once assembled; Figure 7 shows a circuit diagram of the thermal relay with a motor and a contactor; Figure 8a illustrates a side view of the housing of the

  thermal relay-in which the bila-

  my current monitoring; and, Figure 8b illustrates a top view of the same

  thermal relay box as shown in Figure 8 a.

  A thermal relay 1 according to the invention performs a

  protection function of an M motor in a cir-

  baked visible in Figure 7 and using a contactor 90

  having an electromagnet coil 93 which controls the closing

  opening and opening of power switches 96, 97, 98 to establish a connection with the RST network A contact

  auxiliary 95 is also actuated by this electromagnet.

  The thermal relay has input power terminals 100, 101, 102 connected to corresponding terminals of the contactor and output power terminals 103, 104, connected to the motor, and between which are arranged heaters 3 ', 41, 5' which produce the deformation of bimetals 3, 4, 5 placed in their vicinity; these heaters can also be part of the bimetallic strip A safety switch 57, normally closed, is opened by the movement of the bimetals when they reach a predetermined temperature, this temperature being reached at the end of a time interval which is a function of their previous temperature, the ambient temperature and the intensity of the current flowing in the heaters: In the circuit, represented in operation, the coil of

  the electromagnet 93 is connected in series with the interrup-

  safety device 57 and with a switch for

  vice 94 between the poles + and a source and with the terminals 92, 91, 70, 71 The auxiliary contact 95 which is

  connected in parallel on the switch 94 ensures the excita-

  electromagnet when the switch 94 ceases

to be operated.

  When, as a result of abnormal conditions such as an overloaded motor, bilâmes reach a temperature too high, the switch 57 opens and the electromagnet, for lack of excitation, opens the power switches 96,

  97, 98 to interrupt the power supply of the motor.

  The operation of the thermal relay 1, as well as the choice

  certain modes of operation, the setting of the

  nominal capacity of the motor, and the adjustment of the relay at the factory are obtained using the parts shown in Figure lb, where it is noted that this relay, which is externally in the form of a casing 2 uses two casings 2 'and 2 "which are associated

  The 2 "box contains bimetallic strips 3, 4, 5, their heaters

  rettes, their corresponding terminals 100, 1101, 102, 103, 104, 105 and a motion transmission strip 9 which receives the deformations of these bimetals on pushers 6, 7, 8. The housing 2 'contains the safety switch 57, the -6-

  corresponding terminals 70, 71 and a set of or-

  which will be described below.

  An end 10 of the strip which enters the housing 2 'through an opening 12 after passing through an opening 11 of the housing 2 ", is placed opposite one end 13

  belonging to a lever 14 articulated at point 15 on the end.

  17 'of a lever 17 whose opposite end 17 "is

  rotated on the point 18 of the casing 2 '.

  These two levers 14 and 17 constitute a motion transmission mechanism 77 which transmits the movement of the

  ruler to a dead center device 30.

  The transmission of this movement requires, however, that

  point 24 of lever 14 meets a fulcrum-23 belonging to

  to a temperature compensation device

  19 The fulcrum 23 is represented by the

  mité of a bimetal 22 which is fixed on a pivoting frame 20

around a pivot 21.

  A spring 25, placed between the frame 20 on which it is preferably fixed, and a point 26 of the casing 2 ', communicates to

  this frame a couple of clockwise that applies one end

  fixed mate 27 of bimetal 22 against a cam 28 belonging to

  to an intensity adjusting device 65 comprising'par

  Moreover, an adjusting member 29 connected to the cam and moving

  with regard to a scale of intensities 62.

  The dead center passage device 30 comprises a rocking lever 31 which can oscillate about 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 work positions T 1 or T 2

  whose obtaining and properties will be specified below.

below.

  A spring 34, which is stretched between a first point of attachment

  chage 34 'of the lever 31 and a second attachment point 34 "placed on one end 16 of the lever 14 provides the neutral point effect when the axis 34', 34" of the spring passes through the axis

pivot 32.

  A second bearing 35 of the region 33 can bear under the effect of the spring 34 and for each of the positions Ti - 7

: 7

  or T against a stop represented by the end 37 of a

  operating mode selection device 36 This arrangement

  sitif is for example constituted by a cylindrical rod 38 which can slide and rotate in an opening 39 of the casing 2 'so as to place a stud 43 of the box 2' in one of the ends of a groove 42 flowing axially

  and tangentially to the surface of the piece 38

  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 by pushing and rotating

  tion exerted by the user on a head 40 of this

room 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 and 49 respectively 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 another end 46' 'is pivoted at a point 47 of the housing 2' As will be justified later,

  lever 46 and contacts 48, 49 constitute a

  The lever 46 is in fact secured to a first end 50 "of a tension spring 50 having a second end 50 'attached to a movable portion 51 of a position adjusting device 78 When (in -an operating mode for

  which the end 37 has received a position A).

  bimetals 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 bimetal strip 22 after having made a stroke D; the tilting of the lever 14 around the point 24 produces an alignment of the points 34 ', 32 and 34 "which causes immediately after, a sudden tilting of the lever 31 in the clockwise direction, which causes the opening of the switch 57 because of the percussion

lever 46 by the hammer 44.

  The adjusting device comprises a U-shaped part, 53 elastics

  deformable having a fixed branch 55 secured to the housing 2 'and a movable arm 52 which carries the portion

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  -8- mobile 51, the position of the latter can be adjusted using a set screw 54 which is screwed into

  branch 52 and which relies on branch 55

  of the movable portion 51 changes 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 reclosing 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 res-

  spell 34 to give the opening of the switch an unstable character; in this case as soon as the bimetallic bends, the lever 31 automatically returns to its rest position R for which the switch 57 is open. When the bimetallic bursts warm 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 range 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 This change in the values of the couples is due to a

  change of the inclination of the two springs.

  A reset or reclosing of the thermal relay must then be performed, after sufficient cooling of the

  bimetals, to-close the switch 57 manually.

  This reclosing, which can be operated by a separate manual resetting device, can also be effected by an axial thrust, exerted to the left of FIG.

on the 40 button.

  The thermal relay may further comprise an element 73, for

  by lever action 46, the voluntary opening

  switch 57 when a movement of direction B

  communicated to him by the user.

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  The various actions and interactions of the organs that have just been described are found in the functional block diagram of FIG.

  devices are provided with the same references.

  The material realization 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 slider 9, movable in the plane RRI Between two parallel walls 74, 76, placed laterally relative to the cells, a bottom 72 and an outer wall 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 elastic-

  deformable in the direction of the width "q".

  As can be seen better in the top view of FIG. 8b, an outer face 88 of the casing 2 "giving access to the cells is closed by a cover 89 which also closes a

  lateral entrance 99 of housing 87.

  This insulating cover is crossed by the connection terminals.

  100, 101, 102, which are guided by candles 1a, 102a, 103a, and are placed opposite other terminals of

connection 103, 104, 105.

  Two openings 106 and 107 are placed in the outer wall 86 and located substantially in the plane

  PP 'for a purpose defined later, see Figure 8a.

  The housing 87 is intended to receive between two opposite faces.

  Parallel branches 63 and 108 of the partitions 74, 76, the second

  2 'housing whose functions have been specified above.

  With reference to FIG. 2a, it can be seen that inside the housing 2 ', which is here shown in section through the plane PP', is divided by an internal partition 75 into two separate volumes 66 and 67, respectively, which communicate with each other. an upper volume 68, these first two volumes being placed in a region L adjacent to the plane RR 'in which moves

the ruler 9.

  The volume 66 communicates with the outside on the one hand, by a lower opening 85 of the bottom 80 of the housing 2 'and other

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  - Part, through a side window 83 opening on the side of a bearing face 61, see also Figures 4 and Sb, called to cooperate with the face 63 of the wall 74 "The volume 67 communicates with the outside of on the one hand, by a side window 109 opening on the side of the side face and, on the other hand, with a window 84 which opens on the face 61 of the housing 21 and which occupies the entire width of the volume 68 opposite which it is placed , see Figures 2a, 4 and 5 Furthermore, a window 116 opening on the

  face 64 and opposite the window 83 allows the movements

pivoting frame arrangements 20.

  These windows and openings give access to the volumes 66, 67, 68 to allow the assembly of the parts described in FIG. The volume 66 receives mainly the organs of the device

  transmission 77 and the thermal compensation device

  that 19; the volume 67 receives mainly the organs of the switch device 45 and a part of its adjustment device -78; finally the volume 68 mainly receives the organs of the dead-center device 30 and those of the

  intensity adjusting device 65.

  Referring to Figure 2a and incidentally to the figures

  3, -4 and 5, we find that the axes of rotation or pivots

  all the pivots or articulations of the levers used are substantially placed in the plane PP '; at XX 'the axis of the pivot 18, YY' of the articulation is recognized, 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 cuts 18 a, 18 b; 32a, 32b; 47a, 47b,

  who receive knives from the corresponding moving parts

  3, while the frame is pivoted by means of its flanges 20 'on pins 21a, 21b. This method of pivoting with a knife provides a very low value.

  friction and facilitates assembly, while the friction

  more important elements appearing on the nipples 21a, 21b of axis TT 'are easily overcome by the torque exerted on

  the cam 28 at the time of manual adjustment of intensity.

  The axis YY 'of the articulation 15 is also parallel to the

other axes.

  The portion 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 casing 2 'as well as a first conductive part 70 which is fixed on this case and which carries the terminal 70 to connect

  the latter at the fixed contact 49 and that a second conductive part

  71 which is secured to the U-shaped part 53 and on which the lever 46 of the movable contact 48 rests for

connect it to terminal 71.

  The part of the adjustment device protruding out of the

  housing 2 'is an end of the U-shaped piece (53) on the

  which is engaged the screw (54), so that when the removable housing (2 ') is not yet associated with the housing (2 "), it is extremely easy to perform in the factory the

  torque adjustment 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 combination of the two boxes

  third. The intensity adjustment members 29, the choice of the operating mode M or A 40 and the voluntary opening 73 of

  the switch move along or around parallel axes

  II, respectively JJ 'and KK' respectively,

  an upper wall 113 of the housing 2 'which is opposite the bottom 80 and has an upper adjustment face 79 on

  which is for example arranged the intensity scale 62.

  These axes I, J, K are substantially placed in the plane PP '.

  When the housing 2 'is engaged in the direction F in the housing 87 of the housing 2 ", a clearance 114 of the flowing face 61

  parallel to the bottom 80 allows the end 10 of the re-

  9, which is projecting, to be in front of the window 83 which thus constitutes here also the opening 12 of Figure lb, see also Figures 3, 5 and 8 b;

  In order to combine the two housings, the conductors

  70a and 71a are previously without the screws of their

terminal 70 respectively 71.

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  12 - The application of the bearing face 61 of the housing 2 v against the face 63 of the housing 2 "1 is obtained thanks to the elasticity of the wall 76 whose face 108 -sapplique on the face 64 of the

  housing 2 ', see arrow C in Figure 8a.

  The cover 89, which is also placed in the direction F, makes it possible to hold the housing 2 'in place by pressing on the face 112 thereof (see FIG. 8b) by closing the

  housing 87 and closing the cells 3 to D 4 a, 5 a.

  -The reduction of the dimensions of the housing 2 'is mainly

  due to the respective disposition of the coins in the different

  volumes and a lightening of its walls by numerous windows and openings which also facilitate

mounting.

  The electrical insulation of the terminals 70, 71 which is established or completed when the two housings are associated with one or more partitions 86 of the bimetallic housing 2 "is also accompanied by a protection against the environment which is carried out by means of 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 the openings.

13 -

Claims (7)

Patent claims   A thermal relay comprising: a first housing in which current monitoring bimetals are arranged able to communicate their movements to a strip and a second removable box associated with the first such that the strip can communicate to a normally closed safety switch and placed inside a working position for which this switch is open, characterized in that this switch (45), a motion transmission device (77), and a thermal compensation device (19) are arranged in a second housing (2 ') having a small width "q" measured in the direction of movement of the slide (9), and having on several faces (80, 61, 64, 110) access windows (85, 84, 83 , 109, 116) which are closed off by partitions   (72, 63, 86, 76) belonging to the first casing (2 ").   2 thermal relay according to claim 1, characterized in that the second housing (21) is applied against a face (63) of the first casing (2 "') and in the direction C of the strip (9) by an elastic partition (76). ) of this first case.   3 thermal relay according to one of claims 1 or   2, characterized in that the small width "q'l is obtained by a parallel arrangement of the pivot axes (YY ', XX', TT ', ZZ', W ') of levers (14, 17), (20, (30) and (46) which respectively belong to the transmission device (77), to the thermal compensation device (19), to a neutral passage device (30) and to the switch (45), all these axes. being substantially placed in a median plane PP 'of the second casing (2') which is perpendicular to the direction of movement of the slide (9), and the axis pivots XX ', ZZ' and VVW 'using knives and nicks. 14 -   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 displacement RRI of the rail R (9) comprises two neighboring volumes (66) and (67) in which the transmission device (77) and the thermal compensation device (19) on the one hand, and the safety switch (45) on the other hand, the dead-shift device (30) being disposed in a third volume (68) which communicates with the other two and which is further away from said plane of displacement. Thermal relay according to Claim 4, characterized in that an adjusting face (79) which limits the third volume (68) and which is opposite to said displacement plane RRI 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 triggering intensity respectively for   choose one of two modes of operation (A, M) of the re-   latching of the switch, respectively to   kill a voluntary actuation of the safety switch (45).   Thermal relay according to one of claims 1 to   , 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   plane of movement RR 'of the slide (9).   Thermal relay according to Claim 6,   characterized in that a set screw (54) of the interrup-   safety device (45) is accessible on said external face. (110). -   8 thermal relay according to one of claims l to   7, characterized in that cells (3a, 4a, 5a) of the first housing (2 "), in which the bimetals (3, 4, 5) which actuate the slide (9), are closed by a removable cover (89) which also forms an inlet (99) of a housing (87) of this first housing, adapted to receive the second housing (2 ') This housing being particularly limited by the elastic partition (76).