Abstract:
The invention relates to a control unit for an electric vehicle or hybrid vehicle. The control unit has a housing enclosing a cavity. The housing has a housing lid and a housing opening, wherein the housing lid is designed to close the housing opening. According to the invention, the control unit has an electrically insulating shock hazard protection cover, which has at least one projection region extending transversely with respect to a surface of the shock hazard protection cover. The housing lid has at least one receptacle for the projection region, wherein the cutout is designed to retain the projection region in a force-locking manner. The shock hazard protection cover has at least one latching hook designed to latch in a positively locking manner, or additionally in a force-locking manner, with the housing or a part of the control unit in the interior of the housing which is connected to the housing.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a control unit for an electric vehicle or hybrid vehicle. The control unit has a housing enclosing a cavity. The housing has a housing lid and a housing opening, wherein the housing lid is designed to close the housing opening. The hybrid vehicle has at least one electric machine and additionally an internal combustion engine. 
     With control units known from the prior art there is the problem that, when the housing lid of the housing is opened, live parts in the interior of the housing can be contacted, thus posing a danger to a person who opens the housing. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention the control unit of the type described in the introduction has an electrically insulating shock hazard protection cover, which has at least one projection region extending transversely with respect to a surface of the shock hazard protection cover. The housing lid has at least one receptacle, in particular a cutout or a clamp for the projection region, wherein the cutout is designed to securely hold the projection region with a frictional fit. 
     The shock hazard protection cover preferably has at least one latching hook, which is designed to latch, with a form fit or additionally with a frictional fit, with the housing or with part of the control unit that is located in the interior of the housing and that is connected to the housing. A force for releasing the latching of the shock hazard protection cover with the housing is preferably greater than a force for separating the shock hazard protection cover from the housing lid. 
     The housing lid together with the shock hazard protection cover thus can be connected advantageously to the housing part, and the projection region can be separated from the housing lid when the housing lid is opened, wherein the shock hazard protection cover can remain latched to the housing or the part of the control unit in the interior of the housing. More advantageously, the shock hazard protection cover thus can be connected to the housing lid in one manufacturing step. 
     During an assembly of the control unit, the housing lid can be assembled together with the shock hazard protection cover and is thus already connected to the housing lid in a predetermined position. When the control unit housing is to be opened, for example for maintenance or servicing purposes, the housing lid thus can be separated from the housing or swung open for this purpose. As the housing lid is separated or swings open, it can detach from the shock hazard protection cover, insofar as the shock hazard protection cover, by means of the frictional connection, is connected to the housing lid more weakly than to the housing or the part of the control unit in the interior of the housing by means of the interlocked connection. The shock hazard protection cover thus remains connected to the control unit and can hide live electrical components, which are concealed by the shock hazard protection cover, against accidental contact. 
     The control unit is preferably designed to control an electric machine for the movement of the electric vehicle or hybrid vehicle in motor operation and/or in generator operation and to be connected to the electric machine. To this end the control unit preferably has a connector for the electric machine. The control unit more preferably has an inverter, in particular a high-voltage inverter, for feeding current to the electric machine. The high-voltage inverter is designed to connect a voltage of more than 60 volts, preferably more than 400 volts, more preferably between 400 and 1500 volts, to an output connector for the electric machine. 
     The control unit is preferably designed to control a climate compressor and/or an electric heater and to supply these with operating voltage. To this end the control unit has an electrical connector for the climate compressor and/or the heater. 
     The shock hazard protection cover is preferably designed to cover at least one connector, in particular at least one of the connectors for the electric machine or the climate compressor or the heater. 
     In a preferred embodiment the shock hazard protection cover has a resilient seal formed integrally on the shock hazard protection cover. The seal is designed to seal at least an edge of the housing opening and the housing lid with respect to each other. The seal is preferably injection molded onto the shock hazard protection cover. The seal is preferably formed by an elastomer, more preferably by a silicone rubber. Due to the seal, moisture is advantageously prevented from infiltrating the housing. 
     The seal is preferably designed to protrude beyond an edge of the housing lid. In another embodiment the housing lid has, in the region of a housing lid edge, a cutout reaching as far as the seal. The seal can thus be seen advantageously from outside, and a presence of the shock hazard protection cover can be checked. 
     In a preferred embodiment the housing lid has at least one aperture, or a cutout for a screw. The housing preferably has a thread, in particular an inner thread for the screw, wherein the inner thread is arranged in such a way that the housing lid can be tightly screwed to the housing. 
     The housing lid thus can be separably connected to the housing, such that electrical components are accessible from outside for maintenance purposes. 
     The housing lid is preferably connected to the housing by means of a hinge, such that the housing lid can be swung open. The hinge can be formed for example as a latching hinge, which is designed such that the housing lid can be interlocked with the housing when connected for the first time to the housing and remains connected during an opening process following the connection to the housing via the hinge. 
     In a preferred embodiment the shock hazard protection cover has at least one aperture for passing through a probe tip of an electric voltmeter. The control device preferably comprises at least one electrical component, which is designed to convey high voltage. The electrical component is preferably arranged in the cavity enclosed by the housing. The shock hazard protection cover is preferably designed to cover the electrical component in such a way that the electrical component cannot be contacted through the housing opening. 
     The aperture for passing through the probe tip for example has a diameter between two and five millimeters. 
     By the aperture it is advantageously possible to test, once the housing lid has been opened, whether the electrical component is live. After the test the shock hazard protection cover can be removed by release of the latching, such that the electrical component is accessible through the housing opening for maintenance or servicing purposes. 
     In a preferred embodiment a retaining element is integrally formed on the shock hazard protection cover, which retaining element extends transversely with respect to the surface in a direction opposite the projection region. The retaining element is preferably shaped in the manner of a hollow cylinder portion or hollow-cylindrically. The retaining element is designed to engage around a head of a screw, in particular a hexagonal screw, and to securely hold the screw against loosening. A previously mentioned electrical component is preferably formed by means of the screw. 
     The screw is preferably part of an electrical connector for connection of the control unit, wherein the electrical connector is designed to be secured to a cable shoe of an electrical connector cable. To this end the electrical connector comprises the aforementioned screw, which can be securely held by the retaining element against loosening. 
     The previously mentioned cylinder wall for example may have incisions in the direction of a longitudinal extension of the hollow cylinder, such that cylinder wall segments thus formed, which are separated from one another by the incisions, can securely hold the screw head resiliently. 
     The shock hazard protection cover is preferably formed from, in particular, fiber-reinforced plastic. The plastic of the shock hazard protection cover preferably comprises polybutylene terephthalate. The aforementioned seal is preferably injection molded onto the shock hazard protection cover, and for example is formed from liquid silicone rubber. 
     The invention also relates to a method for making safe a control unit, in particular a control unit of the above-described type, comprising a housing enclosing a cavity, said method comprising the steps of: 
     frictionally connecting a shock hazard protection cover to an inner wall of a housing lid; 
     closing a housing opening of the housing with the housing lid, wherein the shock hazard protection cover latches with the housing or part of the control unit connected to the housing (said part preferably being received in the cavity), such that the shock hazard protection cover interlocks with the housing or part. 
     In the method a seal formed integrally on the shock hazard protection cover is preferably trapped between an opening edge of the housing opening and the housing lid as the housing opening is closed, such that the cavity is protected against infiltrating moisture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described hereinafter on the basis of figures and further exemplary embodiments. Further advantageous variants will emerge from the features described in the figures and in the dependent claims. 
         FIG. 1  schematically shows a control device in a sectional illustration, in which electrical connectors are accessible through a housing opening and are concealed by a shock hazard protection cover; 
         FIG. 2  shows the control unit shown in  FIG. 1 , in which the housing lid has been removed, wherein the shock hazard protection cover has separated from the housing lid and remains connected, in particular latched, to the control unit; 
         FIG. 3  shows in a plan view the shock hazard protection cover shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an exemplary embodiment for a control unit  1  for a motor vehicle. The control unit  1  has a housing  3  enclosing a cavity  4 . The housing  3  also has a housing lid  5 , which is designed to close a housing opening  6  of the housing  3 . 
     The cavity  4  enclosed by the housing  3  adjoins the opening  6  of the housing, such that electrical components arranged in the housing  3  can be reached from outside through the opening  6 . 
     The control unit  1  in this exemplary embodiment has, as electrical components, a power output stage  30 , which in this exemplary embodiment has two power semiconductors  28  and  29 , which in this exemplary embodiment are each formed as a power transistor, in particular field-effect transistor or IGBT (IGBT=insulated gate bipolar transistor). 
     The power output stage  30  has an electrical connector  27  connected to the power transistor  29 , and an electrical connector  26  connected to the power transistor  28 . The electrical connector  26  has a screw connector with a screw  24 , and the electrical connector  27  has a screw connector with a screw  25 . The screw connectors  26  and  27  are designed to securely clamp and electrically contact a cable shoe  31  with the screw  24 , and respectively a cable shoe  32  with the screw  25 . 
     The control unit  1  also has a shock hazard protection cover  7 . The shock hazard protection cover  7  is in this exemplary embodiment formed from plastic, in particular glass-fiber-reinforced polybutylene terephthalate, ABS plastic (ABS=acrylonitrile butadiene styrene), or an aliphatic polyamide, in particular a polyamide formed from hexamethylenediamine and adipic acid, in particular also known as PA66. 
     The shock hazard protection cover  7  has a sealing edge  9  as seal, which in this exemplary embodiment is formed integrally on the shock hazard protection cover  7 . The sealing edge  9  is formed in this exemplary embodiment by a silicone rubber, in particular LSR. The sealing edge  9  is designed to seal the housing lid  5 , in particular in the region of a lid edge of the housing lid  5 , against the housing  3  in the region of an opening edge of the opening  6 . 
     The seal  9  projects in the region of a lid edge of the housing lid beyond the lid edge, such that the presence of the shock hazard protection cover can be seen from outside. To this end the seal for example has a signal color, in particular one of the colors red, yellow or orange. 
     The control unit  1  in this exemplary embodiment for this purpose has a screw connection, by means of which the housing lid  5  can be connected to the housing  3 . A screw  23  and a screw  22  are illustrated, which are each designed to connect the housing lid  5  to the housing  3  and to press the housing lid  5  against the housing  3  in the region of the opening edge of the opening  6 . 
     The housing lid  5  has a receiving region  21  pointing in the direction of the cavity  4  and having a cutout. The receiving region  21  is designed to securely hold a projection region  20  with a frictional fit, wherein the projection region  20  is formed integrally on the shock hazard protection cover and extends toward the housing lid  5 , pointing away from a flat extension of the shock hazard protection cover  7 . 
     The shock hazard protection cover  7  in this exemplary embodiment also has two latching hooks  10  and  11 , which each extend in the direction of the cavity  4  and are each formed integrally on the shock hazard protection cover  7 . 
     The shock hazard protection cover  7  in this exemplary embodiment also has an actuation lever  13 , which is arranged on the shock hazard protection cover  7  in the region of the latching hook  11  and extends in the direction of the lid  5 , pointing away from the shock hazard protection cover  7 . The shock hazard protection cover  7  also has an actuation lever  12 , which extends in the direction of the lid  5  and is formed integrally on the shock hazard protection cover  7  in the region of the latching hook  10 . The shock hazard protection cover  7  in the region of each of the actuation levers  13  and  12  has a slit  33  and  34  respectively, such that the actuation levers  13  and  12  can be resiliently pivoted. The shock hazard protection cover  7  is designed to also pivot the latching hook  11  as the actuation lever  13  is pivoted and to also pivot the latching hook  10  as the actuation lever  12  is pivoted. The latching hooks  10  and  11  are each designed and arranged to engage behind the edge of the housing opening  6  in a form-fitting manner. Following an actuation of the actuation levers, the latching hooks  10  and  11  are each pivoted away from the opening edge, such that the shock hazard protection cover  7  can be removed from the housing  3 . In another embodiment the shock hazard protection cover does not have any actuation levers, and instead the latching hook is V-shaped or U-shaped in the region of an aperture in the shock hazard protection cover, wherein a V-limb or U-limb is formed integrally on the shock hazard protection cover, thus forming a resilient pivot joint. The latching hook has a projection region designed to engage behind the housing opening edge, which projection region is formed integrally on the U-limb or V-limb, pointing away therefrom. The latching hook can thus latch with the housing as the shock hazard protection cover is closed. In order to remove the shock hazard protection cover, the latching hook can be pivoted by leverage, by passing a lever tool, for example a screwdriver, through the aperture and into the V-shape or U-shape of the latching hook, such that the projection region can release the shock hazard protection cover. 
     The shock hazard protection cover  7  has a measurement opening  14 , which is arranged in the region of the screw  24 . The shock hazard protection cover  7  also has a measurement opening  15 , which is arranged in the region of the screw  25 . 
     The function of the control unit  1  will now be described hereinafter: 
     In order to assemble the control unit  1 , the electrical connectors  26  and  27  can be connected to a cable shoe  31  and  32  respectively by means of the screw  24  and  25  respectively. The cable shoes  31  and  32  can be guided for example through a housing opening (not illustrated in greater detail in  FIG. 1 ) of the housing  3  to the electrical connectors  26  and  27 . 
     The shock hazard protection cover  7  can be introduced with the projection region  20 , which in this exemplary embodiment is formed as a journal, with the housing lid  5  by inserting the journal  20  into the cutout of the receiving region  21  of the housing lid  5  and can thus be connected to the housing lid  5 . Once the housing lid  5  has been connected to the shock hazard protection cover  7 , the housing lid  5  together with the shock hazard protection cover  7  can be connected to the housing  3  and in so doing can close the housing opening  6 . 
     When connecting the housing lid  5  together with the shock hazard protection cover  7  to the housing  3 , the latching hooks  10  and  11  latch into the housing opening  6  and in so doing each engage behind the housing edge in the region of the housing opening  6 . 
     In this exemplary embodiment a retaining element  16  and a retaining element  17  are also arranged on the shock hazard protection cover  7 , which retaining elements are each formed as a hollow cylinder peripheral portion and are formed integrally on the shock hazard protection cover  7 . The retaining elements  16  and  17  are designed to securely hold the screw  24  and to secure this against loosening. The shock hazard protection cover  7  also has two retaining elements  18  and  19 , which are each formed as hollow cylinder peripheral portions and can jointly securely hold the screw  25 . The hollow cylinder peripheral portions  16  and  17 , similarly to the hollow cylinder peripheral portions  18  and  19 , are each guided toward the screws  24  and  25  respectively as the housing opening  6  is closed and, in an end position in which the latching hooks  10  and  11  each snap into place, surround the screw heads of the screws  24  and  25  respectively. 
     Following a closure of the housing opening  6  of the housing  3 , the housing lid  5  can be fixedly closed by means of the screws  23  and  22 . 
     Here, the peripheral sealing edge  9  seals the gap between the lid  5  and the housing  3  against infiltrating moisture. 
       FIG. 2  shows the control unit illustrated in  FIG. 1 , in which the screws  22  and  23  have each been loosened and removed. The housing lid  5  illustrated in  FIG. 1  has also been removed in the illustration of the control unit  2  shown in  FIG. 2 . The shock hazard protection cover  7  remains fixedly connected to the housing  3  by means of the latching hooks  10  and  11 , whereas the projection region  20  connected only frictionally to the housing lid  5 , in particular the receiving region  21 , can be separated from the receiving region  21  when the housing lid  5  is removed from the housing  3 . The shock hazard protection cover  7  thus remains advantageously connected to the housing  3 , such that the electrical connectors  26  and  27 , which for example are connected to a capacitor carrying high voltage, cannot be contacted from outside. 
     In a further test step, probe tips  35  and  37 , illustrated in  FIG. 2 , of a measuring instrument  38  can be introduced into the measurement opening  14  and into the measurement opening  15  respectively, and in so doing can contact the screw  24  and the screw  25  respectively. By means of the measuring instrument  38 , for example a voltmeter, it is thus possible to test whether the electrical connectors  26  and  27  are live. 
     When the electrical connectors  26  and  27  are each sufficiently de-energized, the shock hazard protection cover  7  can be removed by pivoting the actuation levers  12  and  13 . Upon pivoting the actuation levers  12  and  13 , the latching hooks  11  and  10  are also pivoted, such that the latching books  10  and  11  no longer engage in a form-fitting manner behind the housing edge in the pivoted state. The shock hazard protection cover  7  can then be removed. 
     Following a removal of the shock hazard protection cover  7 , the screws  24  and  25  for example can be loosened, and, following a loosening of the screws  24  and  25 , the cable shoes  31  and  32  can be separated from the electrical connectors  26  and  27 . 
     The housing  3  also has a housing base  2 , which has channels designed for fluid guidance. Of the channels, the channel  36  is referenced by way of example. The power output stage  30  is thermally conductively connected to the housing base  2 . Heat produced by the output power stage  30  can thus be absorbed at the housing base  2 , which for example is formed by a metal block, in particular aluminum block. The heat absorbed by the housing base  2  can be led away further, for example via a fluid flowing in the channels, in particular cooling water. 
       FIG. 3  shows in a plan view the shock hazard protection cover  7  already illustrated in  FIGS. 1 and 2 . The seal formed as a peripheral sealing edge  9  is illustrated, which seal is formed integrally on the shock hazard protection cover  7 . Retaining elements  16  and  17  are also illustrated, which each form segments of a hollow cylinder. The retaining elements  18  and  19  also jointly form segments of a hollow cylinder. 
     The retaining elements  16 ,  17 ,  18  and  19  are each formed integrally on the shock hazard protection cover  7 , in particular are injection molded on and extend in a manner pointing away from a flat extension of the shock hazard protection cover  7 . The shock hazard protection cover can be produced for example in an injection molding method. 
     The latching hooks  10  and  11  are also illustrated, wherein the shock hazard protection cover  7  has, in the region of the latching hooks  10  and  11 , slits  33  and  34  respectively, each extending longitudinally. The shock hazard protection cover  7  can thus deflect in the region of the slits  33  and  34  upon actuation of the actuation levers  13  and  12  illustrated in  FIG. 1 . The latching hooks  11  and  10  can thus be pivoted and can release the form-fitting engagement, formed by means of the latching hooks  10  and  11  and illustrated in  FIG. 1 , behind the opening edge of the housing opening  6 . 
     The measurement opening  14  is arranged in this exemplary embodiment in a middle of the hollow cylinder formed by means of the retaining elements  16  and  17 . The measurement opening  15  is arranged in this exemplary embodiment in a middle of the hollow cylinder formed by the retaining elements  18  and  19 . The screw arranged under the shock hazard protection cover can thus be touched, and a voltage conveyed by the screw can thus be measured.