Patent Publication Number: US-2023148105-A1

Title: High-voltage Relay with Improved Mechanical Shock Tolerance for a Drive or Charging Circuit of an Electric Vehicle with a Rocker as Armature

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date under 35 U.S.C. § 119(a)-(d) of German Patent Application No. 102021129009.0, filed on Nov. 8, 2021. 
     FIELD OF THE INVENTION 
     The invention relates to a high-voltage relay for a drive and/or charging circuit of an electric vehicle. 
     BACKGROUND 
     High electrical voltages are typically used in electric vehicles for the drive and charging components. High amperages can also arise during the charging process and during operation of a battery-electric vehicle. Charging stations with voltages of 400 V and 800 V are already widespread. Higher voltages are conceivable in the future. Currents of more than 15 kA can arise briefly during operation. As a result, the drive and charging components of electric vehicles must be able to carry these currents for a short period of time without the contacts opening with high power consumption due to the repulsion effect of the high currents. 
     Furthermore, the unintentional opening or closing of a circuit due to the high voltages and currents must be reliably prevented. This applies in particular for strong vibrations or shocks, such as can occur while driving an electric vehicle or in the event of an accident. 
     SUMMARY 
     A high-voltage relay includes a magnetic drive assembly having a first yoke and a second yoke spaced apart from one another, and an armature driven by the magnetic drive assembly. The armature is a rocker having a first arm and a second arm extending away from the first yoke. The armature can be tilted between an open position and a switching position and is mounted on the first yoke. The first arm has a switching contact assembly. A magnetic circuit including the first yoke and the second yoke is closed in the switching position by the second arm. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be understood by reference to the following description taken in conjunction with the accompanying figures, in which reference numerals identify features of the invention. 
         FIG.  1    is a schematic representation of a high-voltage relay according to an embodiment in a switching position; 
         FIG.  2    is a schematic representation of the high-voltage relay of  FIG.  1    in an open position; 
         FIG.  3    is a top view of a high-voltage relay according to an embodiment; 
         FIG.  4    is a perspective view of the high-voltage relay of  FIG.  3   ; 
         FIG.  5    is a perspective view of a switching contact assembly of the high-voltage relay of  FIG.  3   ; 
         FIG.  6    is a sectional side view of the switching contact assembly of  FIG.  5   ; 
         FIG.  7    is a perspective view of an armature of the high-voltage relay of  FIG.  3   ; and 
         FIG.  8    is a perspective view of a housing lower part of the high-voltage relay of  FIG.  3   . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     The invention shall be explained hereafter in more detail by way of example using an advantageous embodiment with reference to the drawings. The combination of features shown by way of example in the embodiment can be supplemented by further features in accordance with the properties of the high-voltage relay according to the invention that are necessary for a specific application. Individual features can also be omitted in the embodiment described where the effect of this feature is irrelevant in a specific case of application. The same reference numerals in the drawings are used for elements having the same function and/or the same structure. 
     The basic structure and the function of a high-voltage relay  1  according to the invention shall first be discussed hereafter with reference to  FIGS.  1  and  2   . The high-voltage relay  1  has a magnetic drive assembly  3 . Magnetic drive assembly  3  comprises a core  9  and two yokes, namely a first yoke  5  and a second yoke  7 . 
     The magnetic drive assembly can comprise a coil body  11  with at least one coil turn  13  which extends between two yokes  5  and  7  and around core  9 . Coil body  11  is used to generate a magnetic field in core  9 . Since coil bodies are known, coil body  11  shall not be discussed further at this point. 
     The two yokes  5  and  7  and core  9  may be produced from a metallic material, in particular a ferromagnetic material. 
     As shown in  FIGS.  1  and  2   , the two yokes  5  and  7  are joined together by core  9  and spaced apart by it. Each of two yokes  5  and  7  extends to be substantially transverse to a longitudinal axis  15  of core  9 . 
     Magnetic drive assembly  3  drives an armature  17  of high-voltage relay  1 . Armature  17  is configured as a rocker  19  in the embodiment of  FIGS.  1  and  2    and comprises two arms extending away from one another, namely a first arm  21  and a second arm  23 . 
     Armature  17  configured as a rocker  19  is mounted to be tiltable on first yoke  5 . Armature  17  can be tilted to and fro between a switching position  25 , shown in  FIG.  1   , and an open position  27 , shown in  FIG.  2   . A load circuit can be closed by high-voltage relay  1  in switching position  25  and open in open position  27 . This shall be discussed in detail further below. 
     The rocker  19  can be configured to be V-shaped. Imaginary extensions of both arms  21 ,  23  can there enclose acute angles with a longitudinal axis of the core  9 . The second arm  23 , which closes the magnetic circuit  29  in the switching position  25 , is in the switching position  25  disposed parallel to the longitudinal axis  15  of the core  9  on the two yokes  5 ,  7 . 
     In switching position  25 , shown in  FIG.  1   , a magnetic circuit  29  can be closed by the second arm  23 . Magnetic circuit  29  is indicated by dashed lines in  FIG.  1   . Magnetic circuit  29  can extend through second arm  23 , two yokes  5  and  7 , and core  9 . When magnetic circuit  29  is closed, second arm  23  bears firmly against both yokes  5  and  7 . Switching position  25  can be reached by applying a coil current in coil body  11 . A magnetic field generated in core  9  then also extends through two yokes  5  and  7  and draws second arm  23  towards yokes  5  and  7 . In switching position  25 , second arm  23  can be arranged parallel to longitudinal axis  15  of core  9 . Second arm  23 , in the shown embodiment, has no switching contacts. 
     First arm  21  projects over magnetic drive unit  3 . First arm  21  projects over coil body  11  of magnetic drive assembly  3 . First arm  21  there projects beyond the second yoke  7  over first yoke  5 . In open position  27 , first arm  21  can extend substantially parallel to longitudinal axis  15  of core  9 . 
     In the shown embodiment, armature  17  is configured to roll about first yoke  5  at least during a motion from open position  27  to switching position  25 . An even and smooth transition from the open position  27  to the switched position  25  can be achieved by the rolling motion. In addition, an external support or carrying structure to support the armature  17  against the strong magnetic field of the core  9  may be unnecessary. Instead, the armature  17  supports itself on the first yoke  5  as it rolls. As an alternative to this, armature  17  can also be mounted on a suspension, in particular a hinge or a correspondingly configured return spring, to be able to perform the tilt motion. 
     First yoke  5  can be provided with a bearing  31  for armature  17  at which the cross section of first yoke  5  is enlarged. A sufficiently large contact surface for armature  17  can then be present. 
     In open position  27  shown in  FIG.  2   , there is an air gap  33  present between armature  17  and first yoke  5 . Instead of an air gap  33 , there can also be a layer of lubricant present between armature  17  and first yoke  5 . Due to the fact that armature  17  does not bear directly against first yoke  5  in open position  27 , magnetic remanence in armature  17  can be prevented. 
     In order to facilitate the armature  17  rolling along first yoke  5 , the armature  17  can be provided with a rounded shape, in particular with a semicircular profile, on its side facing first yoke  5 , in particular in the region of a tilt axis  35  of armature  17 . Alternatively, first yoke  5  can be provided with a corresponding profile which facilitates the motion of armature  17  on first yoke  5 . 
     In order to move armature  17  from switching position  25  to open position  27  in an automated manner when the coil current in coil body  11  is switched off, armature  17  can be connected to a spring element  37  which generates a spring force in the direction of open position  27 . In order to be able to move armature  17  safely to switching position  25  when the coil current is switched on, the spring force of spring element  37  is sufficiently small that it does not block armature  17 . 
     First arm  21  is provided with a switching contact assembly  39 , as shown in  FIGS.  1  and  2   . Switching contact assembly  39  is used to close a load circuit  41 , at least a section of a load circuit  41  disposed in high-voltage relay  1 . Such a section is indicated in  FIG.  1   . Load circuit  41  can be in particular a drive and/or charging circuit  41  of an electric vehicle. The second arm  23  is free of a switching contact assembly. 
     High-voltage relay  1  can comprise two load terminals  43  and  45 . Electrical lines of load circuit  41  to be closed can be connected to load terminals  43  and  45 . However, they are not part of high-voltage relay  1 . Load terminal  45  with a switching contact  47  connected thereto is shown merely by way of example. A second switching contact  49  is part of switching contact assembly  39  of high-voltage relay  1 . 
     Switching contact  49  of switching contact assembly  39  is permanently connected in an electrically conductive manner to load terminal  43 . The permanent electrically conductive connection between load terminal  43  and switching contact  49  may be established by way of a flexible electrical conductor  51 , as shown in  FIGS.  1  and  2   . Flexible electrical conductor  51  can be, for example, a stranded wire, a braided cable, or a bundle of thin copper sheets. Alternatively, the flexible electrical conductor  51  can be formed by a resiliently deflectable conductor. 
     Two switching contacts  47  and  49  bear against one another in switching position  25  shown in  FIG.  1   , so that an electrically conductive connection is established between two load terminals  43  and  45  via electrical conductor  51  and two switching contacts  47  and  49 . 
     However, the switching contacts  47  and  49  are separated from one another in open position  27  shown in  FIG.  2    so that current flow no longer takes place. Switching contact assembly  39  comprises an insulating element  53  by which switching contact  49  of switching contact assembly  39  is electrically insulated from the remainder of armature  17 , in particular from second arm  23 . In addition, switching contact assembly  39  can comprise at least one contact spring with which the contact pressure of switching contact  49  against switching contact  47  in switching position  25  is ensured. 
     In order to prevent high-voltage relay  1  from unintentionally closing load circuit  41 , or to prevent an unwanted motion of armature  17  from open position  27  to switching position  25 , the moments of inertia of both arms  21  and  23  may be substantially equal. The term “equal” is presently to mean that a deviation in the moments of inertia is at most 10%. 
     A center of gravity of the rocker  19 , when viewed along the longitudinal axis  15  of the core  9 , is at the height of the tilt axis  35 . When viewed along a longitudinal axis  15  of the core  9 , the tilt axis  35  is at the height of the first yoke  5 .h 
     Since first arm  21  is provided with switching contact assembly  39 , material can be removed from arm  21  elsewhere on arm  21  in order to adapt the moment of inertia of first arm  21  to that of second arm  23 . As an alternative to this, second arm  23  can be loaded with additional mass in order to adapt the moment of inertia of second arm  23  to that of first arm  21 . The same moments of inertia of arms  21  and  23  can lead to vibrations or shocks accelerating both arms  21  and  23  equally, so that there is no unwanted switching from one position to the other. 
     As shown in  FIGS.  1  and  2   , high-voltage relay  1  can comprise one or more locking devices  55  configured to prevent armature  17  from moving away from first yoke  5  beyond a predetermined amount. The predetermined amount can be such that armature  17  can move sufficiently far away from first yoke  5  to form air gap  33 . Locking device  55 , which is only indicated as a small box in  FIGS.  1  and  2   , can prevent entire armature  17  from being accelerated away from magnetic drive assembly  3  in the event of a strong mechanical shock or vibration. In the simplest case, locking device  55  consists of at least one barrier  57  which is arranged above armature  17  and prevents a motion away from magnetic drive assembly  3 . 
     An embodiment of a high-voltage relay  1  according to the invention shall be described hereafter with reference to  FIGS.  3  to  8   . The basic structure of high-voltage relay  1  corresponds to high-voltage relay  1  described with reference to  FIGS.  1  and  2   . For the sake of brevity, only deviations from high-voltage relay  1  previously described or details that have not yet been mentioned shall be described below. 
     High-voltage relay  1  comprises a spring element  37  which is attached to first yoke  5  and to an upper side of second arm  23 . Spring element  37  comprises two arms  59 , shown in  FIG.  4   , which are spaced apart from one another along tilt axis  35  of armature  17  and which are each attached to first yoke  5 . 
     A total width along tilt axis  35  of spring element  37  corresponds substantially to the width of armature  17  in the same direction. In order to reach the upper side of armature  17 , the armature  17  is therefore provided with two recesses  61  which are disposed opposite one another along tilt axis  35  and extend from the outside into the material of armature  17 , as shown in  FIG.  7   . Arms  59  of spring element  37  can extend through these recesses  61  between the upper side of armature  17  and first yoke  5 . 
     First arm  21  is provided with an embodiment of a switching contact assembly  39 . It shall be discussed hereafter with reference to  FIGS.  3  to  6   . Switching contact assembly  39  comprises insulating element  53  which is produced from plastic material. Insulating element  53  is configured to be attachable to first arm  21 . It comprises a base plate  63  which runs parallel to first arm  21  in the assembled state. 
     A web  67  extends on an underside  65  of base plate  63  that faces first arm  21  in the assembled state, as shown in  FIG.  5   . In the assembled state, web  67  may run parallel to a longitudinal extension of first arm  21 . Web  67  can be received in a clamping receptacle  69  in first arm  21  that is configured to be complementary to the former. Clamping receptacle  69 , shown in  FIG.  7   , extends from an end of first arm  21  disposed opposite second arm  23  in the direction toward second arm  23  into the material of armature  17 . Web  67  can be pushed into clamping receptacle  69 . Due to a retaining structure  71  on inner wall  73  in armature  17  defining clamping receptacle  69 , web  67  can be held on first arm  21  in a frictionally-engaged and/or positive-fit manner. 
     A locking plate  75 , which runs parallel to base plate  63 , extends at one end of web  67  disposed opposite base plate  63 , as shown in  FIGS.  5  and  6   . Locking plate  75  can bear against an underside of first arm  21  so that switching contact assembly  39  is held in a positive-fit manner on first arm  21  also in a direction extending transverse to tilt axis  35  and transverse to the longitudinal extension of first arm  21 . 
     A spring retention structure  77  is arranged on a side of switching contact assembly  39  which in the mounted state on armature  17  is closer to tilt axis  35 . Spring retention structure  77  may be formed monolithically with base plate  63 . 
     Two contact springs  79  are held in spring retention structure  77 . Each contact spring  79  carries a switching contact  49 , as shown in  FIG.  5   . Contact springs  79  have an overall flat shape and extend parallel to base plate  63 , at least in open position  27 . Contact springs  79  are spaced from base plate  63 . 
     Contact springs  79  are received in spring retention structure  77 . A holding part  81  shown in  FIG.  6   , for example, a respective holding part  81  for each contact spring  79 , extends through a passage opening  83  in contact spring  79  into a receptacle  85  in spring retention structure  77 . Holding part  81  can be clamped in receptacle  85 . As a result, contact springs  79  are held reliably at the remainder of switching contact assembly  39 . 
     Each contact spring  79  may be formed from several parts. According to an embodiment, each spring retention structure  77  comprises an upper spring plate  87  and a lower spring plate  89 . Both spring plates  87  and  89  are formed from spring steel. Upper spring plates  87  and lower spring plates  89  of two contact springs  79  can alternatively each be formed monolithically. This means that an upper spring steel sheet, in particular a U-shaped spring steel sheet, forms the two upper spring plates  87 . Correspondingly, a lower spring steel sheet, in particular a U-shaped spring steel sheet, can form the two lower spring plates  89 . A single holding part  81  can then be sufficient for attaching the two spring steel sheets to spring retention structure  77 . 
     Since contact springs  79  are intended to be movable along a contacting direction  91  in a resilient manner, two spring plates  87  and  89  may be firmly connected to one another not along their entire length. Instead, they are held to be displaceable relative to one another at least at their end  93  disposed opposite spring retention structure  77 . Contacting direction  91  extends to be perpendicular to the plate planes spanned by spring plates  87  and  89 . 
     Upper spring plate  87  is provided with a contact plate  95  on its upper side, as shown in  FIG.  6   , so that upper spring plate  87  is arranged between contact plate  95  and lower spring plate  89 . Contact plate  95  can be firmly connected to upper spring plate  87 . However, this is not mandatory. Contact plate  95  may be made of a material that is selected with regard to good electrical conductivity, for example, an alloy containing copper or an alloy containing aluminum. 
     Each of two contact plates  95  is connected in an electrically conductive manner to one of two flexible electrical conductors  51 . For example, each conductor  51  can be welded, soldered, or riveted to associated contact plate  95 . 
     Each switching contact  49  of a contact spring  79  is connected in an electrically conductive manner to contact plate  95  of that contact spring  79 . In other words, each contact plate  95  establishes the electrical connection between an electrical conductor  51  and a switching contact  49 . 
     A switching contact  49  extends through contact plate  95  and two spring plates  87  and  89  of its contact spring  79 . For switching contact  49  not to prevent spring plates  87  and  89  from moving relative to one another, lower spring plate  89  is provided with a receptacle  97  for switching contact  49 , the clear width of which is greater than the diameter of switching contact  49  in the region of lower spring plate  89 . This allows switching contact  49  to be movable relative to lower spring plate  89 . In contrast, switching contact  49  may be connected in a positive-fit manner to upper spring plate  87 . 
     In switching position  25 , switching contact assembly  39  is moved so far from second arm  21  in the direction of switching contacts  47  that switching contacts  49  of switching contact assembly  39  already bear against switching contacts  47  of load terminal  45  before final switching position  25  has been reached. In final switching position  25 , first arm  21  with switching contact assembly  39  is moved so far in the direction of switching contacts  47  that contact springs  79  are deflected downwardly, i.e. in the direction towards base plate  63 . As a result, a uniformly high contact pressure of switching contacts  49  upon switching contacts  47  can be ensured. The strong contact pressure also makes it possible to prevent very high currents from leading to electromagnetic repulsion of switching contacts  49  from switching contacts  47 . 
     Both switching contacts  47  are there connected to a common load terminal  45 , each with a dedicated flexible conductor  51 . Due to the division into two switching contacts  47 , the amperage per contact can be halved. Halving the amperage per contact has the advantage that the electromagnetic repulsion of the switching contacts  47  from their mating contacts at high currents is reduced. This in turn means that less magnetic attraction of the magnetic drive assembly  3  is required to hold the armature  17  in the switching position  25 . This in turn can lead to a lower demand for coil current in the coil body  11 . 
     The armature  17  is provided with two projections  99 , shown in  FIG.  7   , that are disposed oppositely along tilt axis  35  and that are part of locking device  55 . A housing  101  of high-voltage relay  1  is provided with a receptacle  103  for each of projections  99 . Only a housing underside  105  of housing  101  with a receptacle  103  for a projection  99  is shown in  FIG.  8   . Receptacle  103  is defined by a barrier  57  which is part of locking device  55 . The barrier  57  prevents second arm  23  from moving away from magnetic drive unit  3  and is likewise part of locking device  55 . In this case, second arm  23  can be regarded as a projection of armature  17  which is prevented by barrier  57  from any unwanted motion. 
     The high-voltage relay  1  for a drive and/or charging circuit of an electric vehicle enables safe operation of an electric vehicle even at high electrical voltages and high amperages and prevents unintentional opening or closing due to the effect of high acceleration (a &gt; 50 g) of the circuit connected to the high-voltage relay  1 . Due to the configuration as a rocker  19 , both arms  21 ,  23  can be accelerated equally in the event of an external disturbance, for example an impact. The forces on both arms  21 ,  23  can then cancel each other out. This can prevent unintentional switching to the switching position  25  or to the open position  27 . The relay  1  is therefore impact resistant. 
     Due to the fact that both arms  21 ,  23  perform different tasks, safety can also be increased because the second arm  23  can be associated only with closing the magnetic circuit, while the first arm  21  is responsible for switching the switching contacts  47 ,  49  of the high-voltage relay  1 . Due to the configuration as a rocker  19 , a spatial separation can be effected. Since the rocker  19  is mounted at, in particular, on the first one of the two yokes  5 ,  7 , it can be drawn with its tilt axis  35  toward the first yoke  5  and supported thereon when the magnetic circuit is closed. At the same time, the second arm  23  closes the magnetic circuit by bearing against the second yoke  7 . High mechanical stability of the high-voltage relay  1  is achieved by this arrangement. The high-voltage relay  1  according to the invention can be used for the typical charging voltages of &lt;1000 V and beyond. In addition, it can carry currents of up to 15 kA for a short period of time, wherein the short period of time denotes a period of less than 2 ms. 
     The high-voltage relay  1  can be configured in particular to hold the respective switching position without switching over unintentionally, even in the event of impacts of up to 90 g. “g” stands for the gravitational acceleration of 9.81 m/s 2 . The impact resistance can be obtained in particular by the armature  17  being configured as a rocker  19 .