Abstract:
An electromagnetic relay including at least one contact-set support in which a plurality of contact springs are fixed at the base end and, in pairs, form normally open and/or normally closed contacts, wherein at least one actuator acts on each active contact spring, the actuator being movably driven in the longitudinal direction thereof by a magnet system and having actuating surfaces for acting on the respective contact spring to be actuated, the actuating surfaces assigned to each of the active contact springs forming an angle with the direction of actuation of the actuator.

Description:
FIELD 
       [0001]    The invention relates to a relay having a modified force-displacement characteristic having at least one contact-set support in which a plurality of contact springs are fixed at the base end and, in pairs, form normally open and/or normally closed contacts, wherein at least one actuator acts on the respective active contact springs. 
       BACKGROUND 
       [0002]    One relay has become known, for example, with the subject matter of EP 1 121 700 B2. This relay discloses a matching of the force-displacement characteristic to the drive characteristic in such a way that the actuator operates in two different actuation planes. That is to say, the actuator for the normally dosed contacts is in a different horizontal plane than, by comparison, the actuator for the normally open contacts. On movement of the actuator, the normally dosed contact opens first, before the normally open contact is dosed via an offset movement. This means that the force required by the actuation of the normally open contacts must be applied by the drive with delayed movement. This has the effect that the force-displacement characteristic of the contact set is modified. This provides the advantage that the drive characteristic and the contact-set characteristic are being matched to one another. 
         [0003]    From the cited printed publication it follows that, in the normal state, the actuator is located, for example, at a certain point s 1  (or to the right thereof) according to  FIG. 7  of said printed publication, the point s 1  being dependent on the degree of contact erosion. On attraction of the armature, the actuator moves to the left, with the force m of the magnet system initially increasing only slowly. However, in this region, up to a point s 2 , the actuating force required to overcome the normally-closed contact force (at the active normally-closed contact spring or at the anchor spring adapted thereto) is still relatively low as well, because of the large mechanical advantage. 
         [0004]    From a point s 2  to s 3 , a greater increasing restoring force is created by the added action of the active normally-open contact springs, which restoring force is overcome by a magnetic force m of the drive system that likewise increases more strongly in this region. From a point s 3  to the mutual abutment of the contacts, both the restoring force f and the magnetic force increase substantially. This is the region of the overtravel, which continues to a point s 4 . The figures mentioned refer to FIG. 7 of EP 1 121 700 B2 and to  FIG. 8  of the present invention, in which  FIG. 7  of the cited printed publication has been plotted as prior art. 
         [0005]    It is therefore the object of said printed publication to match the force-displacement characteristic or—as it is better termed in the description below, the contact-set characteristic, —to the discontinuous operating stroke (drive characteristic) of the magnet system. 
         [0006]    In particular, the contact-set characteristic should not intersect with the drive characteristic of the magnet system, as this would result in unstable actuator travel, and speedy, smooth and continuous actuation of the contact set would no longer be ensured. 
         [0007]    The printed publication cited solves this problem of the modification or modeling of the contact-set characteristic against a constant, consistent drive characteristic in such a way that the actuator acts on the contact set in two different planes. 
         [0008]    In said printed publication, the points of contact engagement by the actuator on the associated contacts are dedicated and remain at a fixed, unchangeable distance from each other during the actuator travel. The mechanical advantage therefore is fixed. This means the distance between the point of fixation of each spring and the plane of actuation of this spring. A change-over from one plane of the points of application of force to another during the actuation does not take place. The height difference between the two actuation planes that are specified in the cited printed publication EP 1 121 700 B2, does not change. 
         [0009]    It is characterizing for EP1 121 700 B2 that only a single actuation plane of the actuator is associated with each, the actuation of the normally closed contacts and the actuation of the normally open contacts, and therefore one contact type (normally closed or normally open) is assigned to each actuation plane. One distance, the distance between actuation plane  1  and the point of fixation of the spring, is associated with the normally open contact and the other distance, between actuation plane  2  and the point of fixation of the spring is associated with the normally closed contact. 
       SUMMARY 
       [0010]    The problem addressed by the present invention is therefore that of improving a relay having a modified force-displacement characteristic of the kind mentioned at the beginning, in such a way that an improved and also variable matching of the contact-set characteristic to a drive characteristic of a drive system of a relay is possible. 
         [0011]    To solve this problem, the invention provides a method for operating an electromagnetic relay comprising at least one contact-set support in which a plurality of contact springs are fixed at the base end and, in pairs, form normally open and/or normally closed contacts, wherein at least one actuator acts on the respective active contact springs, the actuator being movably driven in the longitudinal direction thereof by a magnet system and having actuating surfaces for acting on the respective contact spring to be actuated, wherein during the stroke of the actuator a change-over from one actuation plane to another actuation plane takes place on the active contact springs. 
         [0012]    It is an essential feature of the invention that during the stroke of the actuator, the actuation of the active contact springs transitions from a first actuation plane to a second actuation plane. Owing to the design of the surface between the two actuation planes of the actuator, a discontinuous (abrupt) transition from plane  1  to plane  2  can be rendered continuous. 
         [0013]    The present technical teaching additionally provides the advantage that a continuous transition from one actuation plane to the other actuation plane can be achieved due to the fact that the invention provides that each of the cams of the actuator that are associated with the active springs each has an actuating surface that not only forms, in the direction of actuation of the actuator, an angle relative to the direction of travel of the actuator, but is additionally provided with a curvature. 
         [0014]    This achieves that the actuator bears with an actuating surface bearing obliquely relative to the point of engagement on the spring to be actuated against the contact spring to be actuated, such that as the actuator travel of the actuator continues, the spring to be actuated is first engaged and actuated at the upper end thereof (plane  1 )—a great distance from the point of fixation thereof—and that during this actuator travel, the point of application of force, owing to the actuating surface being designed to be inclined, moves in a downward direction, toward the point of fixation of the spring (plane  2 ). 
         [0015]    As the deflection of the actuated spring increases, the actuator now acts with the inclined cam thereof further down on the spring to be actuated. Thus, the point of force application is shifted during the movement of the actuator and action on the active spring to be actuated, from an upper point (plane  1 ) to a lower point (plane  2 ), said shifting of the point of force application preferably being continuous. 
         [0016]    Depending on the design of the surfaces of the cams between the two operating planes, the transition from plane  1  to plane  2  can occur abruptly (discontinuous) or be rendered continuous. 
         [0017]    With a curved surface on the respective cam, there is no abrupt change-over from an upper to a lower point of application of force on the active spring, hut rather the points of application of force move nearly continuous along the contact spring during the movement of the actuator, from an upper point of application of force (plane  1 ) toward a lower point of application of force (plane  2 ). 
         [0018]    The term “nearly continuous” means that the longitudinal movement of the actuating surface on the actuator occurs (as) interruption-free (as possible) along the length of the contact spring. In the prior art, such a transition from one actuation plane to the other along the length of the contact spring does not exist. The prior art does not change actuation planes. 
         [0019]    This creates the advantage over EP1 121 700 B2, that no choppy contact-set characteristic is generated, but instead a continuous contact-set characteristic is attained, which may be formed in a first embodiment of continuous, relatively straight curve branches, and in a second embodiment of curve branches that are nearly curved, so as to permit an even better rounded shape of the contact-set characteristic. 
         [0020]    All of the above definitions apply to the embodiment shown in  FIG. 8 , in which the drive characteristic and a contact-set characteristic according to the prior art are compared to a contact-set curve according to the invention. 
         [0021]    In a preferred embodiment of the invention, it is provided that the cams of the actuator that form the actuating surfaces are at an angle to the vertical, with the proviso that it is assumed that the actuator operates in a horizontal direction. 
         [0022]    The size of the angle of the actuating surface to the vertical determines the travel point of transition from the upper point of application of force to the lower point of application of force. 
         [0023]    In a first embodiment of the invention it is provided that this actuating surface that is inclined at an angle is designed to be straight in itself. 
         [0024]    in another embodiment of the invention it is provided that this actuating surface is designed to be convex. This means that the contact-set characteristic effected thereby is formed not of continuous straight curve branches—as in the case of a straight actuating surface—but that such a contact-set characteristic additionally has rounded curve branches. 
         [0025]    Owing to the attainment of rounded contact-set characteristic curve branches, an even more continuous transition from one state of the contact springs to the other state is achieved, without the risk that unstable switching states could occur in the intermediate path between these two contact states. 
         [0026]    The subject matter of the present invention derives not only from the subject matter of the individual claims but also from the individual claims taken in combination with each other. 
         [0027]    All of the details and features disclosed in the documents, including in the Abstract, and in particular the physical embodiment illustrated in the drawings, are claimed as essential to the invention in so far as they are novel, whether separately or in combination, with respect to the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention will now be described in detail with reference to drawings illustrating a number of ways of carrying out the invention. Further features essential to the invention and advantages of the invention will be apparent from the drawings and from their description. 
           [0029]    In the drawings, 
           [0030]      FIG. 1  shows a schematized section through a relay according to the invention in the normal state; 
           [0031]      FIG. 2  shows the relay of  FIG. 1  in the normal state, with further details shown; 
           [0032]      FIG. 3  shows the relay according to  FIGS. 1 and 2  in an intermediate state; 
           [0033]      FIG. 4  shows the relay according to  FIGS. 1 to 3  in the energized state; 
           [0034]      FIG. 5  shows the relay according to  FIG. 1  in the normal state, without the contact springs; 
           [0035]      FIG. 6  shows an enlarged view of an actuating surface on the actuator in two different embodiments; 
           [0036]      FIG. 7  shows a third embodiment of the design of the actuating surface on an actuator; and 
           [0037]      FIG. 8  shows the force-displacement characteristic of a drive system according to the prior art in a comparison with a contact-set characteristic according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]      FIGS. 1 to 4  generally show an electromagnetically actuated relay, in which the individual contacts may be provided in pairs or as single contacts. According to  FIG. 2 , for example, a normally open contact  22 , a further normally open contact  23  and one normally closed contact  24  are present, all of which are jointly actuated by one actuator  7 . The actuator  7  is moved in the direction of arrow  5  in the operating state thereof and retracted into the normal state thereof in the direction of arrow  6  by a spring  3  engaging the rearward end thereof. 
         [0039]    The actuator  7  is driven by an armature  2  that is pivot-mounted in a pivot bearing  4  in the region of a contact set support  1 . The armature  2  is driven by a drive coil  21  in the direction of arrow  5 . 
         [0040]    In the embodiment shown, the actuator  7  is made up of a flat insulating material and forms cams  8 ,  10 ,  12 ,  14  disposed one behind the other, with a slot  9 ,  11 ,  13  arranged therebetween in each case. 
         [0041]    In the slot  9  in front of the cam  8 , the active contact spring  15  is arranged, which bears under the natural tension thereof against the associated passive contact spring  18  and forms in the normal state the normally closed contact  24 . 
         [0042]    Conversely, the active contact spring  16  forms a normally open contact  23  together with the passive contact spring  19 , the movement of the active contact spring  16  being is effected by the cam  12  and by an actuating surface  26  to be described later. 
         [0043]    Lastly, the normally open contact  22  is formed by the active contact spring  17  which, in the normal state shown, is arranged at a distance from the passive contact spring  20 .  FIG. 3  shows an intermediate state of the movement of the actuator  7  in the direction of arrow  5 , while  FIG. 4  shows the fully dosed energized state of the relay. 
         [0044]    From the comparison of  FIG. 3  with  FIGS. 1 and 2 , it is apparent that, due to the actuating surface  26  on the cams  8 ,  10 ,  12 ,  14  being designed to be inclined, first an upper point of force application  25  of the actuator is defined that acts on the upper free end of the respective active contact spring  15 ,  16 ,  17 . 
         [0045]    As the movement of the actuator  7  continues in the direction of arrow  5 , the energized state of  FIG. 4  is reached and it is apparent that the point of force application  25  has shifted downward into the point of force application  27 . 
         [0046]    According to the invention it is thus shown that owing to an actuating surface  26  of the actuator that is oriented obliquely to the vertical  35 , and which, together with the vertical  35  forms an angle  36  (see  FIG. 6 ), a shifting of the point of force application  25  to the point of force application  27  located vertically below the former, is effected along the contact spring. 
         [0047]    On actuation of the contact spring in the upper point of force application  25 , a relatively small actuating force of the drive system is required while, on actuation of the respective contact spring  15 - 17 , the points of force application  27  moving toward the point of fixation require a higher actuating force of the drive system. 
         [0048]      FIG. 5  accordingly shows an actuator according to the invention having actuating surfaces  26  inclined obliquely to the vertical. Moreover, it is not essential to the solution that the actuating surfaces  26  on the cams  8 ,  10 ,  12  that actuate the active contact springs  15 - 17  are designed to be identically inclined. They can have differing inclines or shapes. 
         [0049]    In the embodiment of  FIG. 6 , it is shown that instead of an actuating surface  26  that is designed to be straight and inclined at an angle  36  to the vertical  35 , a cambered actuating surface  26 ′ can be used that is designed to be convex, for example. 
         [0050]    Through the use of such a convex actuating surface  26 ′, rounded curve branches are achieved in the force-displacement diagram according to  FIG. 8 , as will be explained below. 
         [0051]      FIG. 7  shows that, instead of an actuating surface  26 ′ that is designed to be convex, it is possible to use an actuating surface  26 ″ that is designed to be concave, which means that the surfaces  26 ″ do not come into engagement with the respective spring, but that merely, on movement of the actuator  7  in the direction of arrow  5 , the engagement at the upper point of force application  25  immediately jumps to the action onto the lower point of force application  27 , without there being a transition in this case. 
         [0052]      FIG. 8  shows the advantages of the invention over the prior art. 
         [0053]    A force-displacement diagram is plotted, the plotted number values being intended merely as examples. They are in no way limiting to the present invention. 
         [0054]    It is essential that, in a relay having a coil drive system, an approximately curved drive characteristic  28  is achieved at all times, which is designated by the letter f and is part of the prior art. 
         [0055]    Furthermore,  FIG. 8  shows that it is part of the prior art that discontinuous curve branches  31 ,  29 ,  37  form a contact-set characteristic according to the prior art. However, it is a disadvantage in the case of such a contact-set characteristic having discontinuous straight curve branches, that an abrupt transition during actuation of the individual active contact springs  15 - 17  must be accepted, which is undesirable. 
         [0056]    This is where the invention sets in which, by virtue of the specifically designed actuating surface  26  on the cams  8 ,  10 ,  12  of the actuator  7  instead proposes continuous curve branches. 
         [0057]    On initial actuation of the actuator  7 , the curve branch  31  is generated that is part of the prior art. This is where the actuation of the active contact spring  15 - 17  at the upper point of force application  25  at the point s 4  begins. As a result, a straight or slightly inclined curve branch  32  is attained, which is referred to as a whole as contact-set characteristic  30  according to the invention. 
         [0058]    It is characteristic that between the points of s 5  and s 6  a straight, or—in the case of a convex actuating surface—a curved curve branch  32  is attained that has a substantially greater distance from the existing drive characteristic  28  and thereby ensures stable state switching of the contact springs. 
         [0059]    In point s 6  the upper point of force application  27  takes effect, and then, as the movement progresses along the contact-set characteristic  30 , branches in point s 6  into the steeper curve branch  33 . 
         [0060]    From the comparison of the contact-set characteristic  29  that is part of the prior art, with the contact-set characteristic  30  that is part of the invention, it is apparent that a simple modulation or influencing of the contact-set characteristic can be achieved with much less effort, namely simply by modifying the actuating surfaces on the cams  8 ,  10 ,  12  of the actuator  7 . This was not previously possible with the prior art. 
       DRAWING LEGEND 
       [0000]    
       
           1  contact-set support 
           2  armature 
           3  spring 
           4  pivot joint 
           5  direction of arrow 
           6  direction of arrow 
           7  actuator 
           8  cam 
           9  slot 
           10  cam 
           11  slot 
           12  cam 
           13  slot 
           14  cam 
           15  active contact spring 
           16  active contact spring 
           17  active contact spring 
           18  passive contact spring 
           19  passive contact spring 
           20  passive contact spring 
           21  drive coil 
           22  normally open contact 
           23  normally open contact 
           24  normally closed contact 
           25  point of force application (upper) 
           26  actuating surface cam  10 ,  12 ,  14 ) 
           27  point of force application (lower) 
           28  drive characteristic 
           29  contact-set characteristic (prior art) 
           30  contact-set characteristic (invention) 
           31  curve branch (of  30 ) 
           32  curve branch 
           33  curve branch 
           34  direction of arrow 
           35  vertical 
           36  angle 
           37  curve branch