Abstract:
The invention relates to a simulation switch for incorporation into a flight simulator and to the simulation of an excess-current circuit breaker which can be manually actuated using an actuating element ( 10 ). The inventive simulation switch comprises a switching mechanism that is identical to the switching mechanism of the excess-current circuit breaker ( 9 ) for opening and closing a switching contact ( 2, 4 ), in addition to an electromagnetic release device ( 20 ) for releasing the closed switching contact ( 2, 4 ) by means of a control current (i).

Description:
BACKGROUND 
   The invention relates to a simulation switch for incorporation into a flight simulator and to the simulation of an excess-current circuit breaker which can be manually actuated using an actuating element. 
   Flight simulators are used to train pilots since dry runs on land are first needed so that the pilots can master the complexity of modern cockpits before they are allowed to practice in an actual airplane. In such a flight simulator, all of the operating and display elements found in an actual cockpit have to be available in an identical version, at least in the interface to the pilot, in order to convey the most realistic impression possible. 
   Thus, the simulation switches used in the flight simulator to simulate the circuit breakers of the type known, for example, from German Published Examined Application No. DE-AS 1 191 030 or German Utility Model Nos. DE-GM 8 904 064 and 89 04 065, all three of which are herewith incorporated by reference herein, have to be the same as those that are present to safeguard the power circuits in the actual airplane. In this context, the feel of the mechanical switching when the simulation switch is manually actuated must not differ from the feel of the switching during the manual actuation of a circuit breaker found in an actual airplane. For this reason, the same circuit breakers are installed in the flight simulator that are also used in the actual airplane. However, since the circuit breakers used in the flight simulator do not have to safeguard any actual power circuits, thermal circuit breakers are used whose rated current is as low as possible (typically 200 to 500 mA) so that this circuit breaker can be systematically released with the smallest possible currents and thus with the lowest possible dissipation power. Nevertheless, the necessary release currents are in the ampere range. This leads to relatively high energy values (˜i 2 t) to actuate the simulation switch, as a result of which the supply network of the flight simulator has to be dimensioned accordingly. Moreover, due to the thermal release, the release times are in the range of seconds. This has to be taken into account by correspondingly long actuation times in the software used for the flight simulator in order to simulate the actual release times for every possible operational case or malfunction state. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a simulation switch for incorporation into a flight simulator and to provide a simulation of an excess-current circuit breaker which can be manually actuated using an actuating element, whereby the above-mentioned drawbacks are largely avoided. 
   The present intention provides a simulation switch for a flight simulator for simulating an excess-current circuit breaker manually actuatable using an actuating element. The simulation switch includes a switching mechanism configured for opening and closing a switching contact, the switching mechanism being the same as a switching mechanism of the excess-current circuit breaker. Also included is an electromagnetic release device configured for releasing the switching contact using a control current when the switching contact is closed. 
   The simulation switch according to the invention comprises a switching mechanism that is the same as the switching mechanism of the excess-current circuit breaker for opening and closing a switching contact as well as comprising an electromagnetic release device for releasing the closed switching contact by means of a control current. Through this measure, on the one hand, the mechanical feel of the switching is not different from that of an excess-current circuit breaker used in an actual on-board network. Since the release of the simulation switch, that is to say, the opening of the switching contacts and the unlocking of the actuation element are effectuated by an electromagnetic release device, on the other hand, small control currents are sufficient to make the simulation switch respond. Moreover, through the use of an electromagnetic release device, the release time can be markedly reduced as compared to thermally released simulation switches. Thus, the control current needed for the release at a typical control voltage of 28 V lies in the order of magnitude of about 100 mA and the actuation time needed is less than 10 ms. Consequently, the actuation energy required drops by a factor of 500 to 1000 in comparison to the actuation energy required with the prior-art simulation switches involving thermal release. 
   In an advantageous embodiment, the electromagnetic release device is electrically connected in series to the switching segment formed by the switching contacts. Through this measure, the control current needed for actuating the electromagnetic release device switches off automatically when the switching contacts are opened, thus avoiding an overload of the release device. 
   In particular, the electromagnetic release device comprises a relay with a pull armature for unlocking a latching mechanism that is operative in the closed position of at least one of the switching contacts, whereby the coil of the relay is preferably connected in series to the switching segment. 
   In another preferred embodiment of the invention, a protective diode is connected in parallel or in series to the winding of the coil of the relay. In this manner, the harmful voltage effects on the control electronics when the coil inductivity is switched off are limited. 
   In another preferred embodiment of the invention, the simulation switch contains at least one electric housing-external connection contact that can be inserted with an internal contact part into the fully assembled housing, where it is affixed in the inserted state and is in electric contact with a housing-internal connection contact via the internal contact part. In this manner, different connection modalities, e.g. a plugged connection, soldered connection, screwed connection or wire-wrap connection, can be provided with just one single type of switch. The simulation switch can then be supplied without connection contacts. The various connection modalities can then subsequently be inserted into the fully assembled housing by the customers as a function of their specific requirements. Such final assembly by the customers is advantageous both in terms of production and storage. 
   Preferably, the electric contact between the housing-internal connection contact and the housing-external connection contact is independent of the mechanical fixation of the housing-external connection contact. As a result, a mechanical load on the housing-external connection contact does not have a detrimental effect on the electric contact. 
   In particular, the housing-internal connection contact consists of a contact spring mounted in the housing, whereby preferably the contact force acts perpendicular to the direction of insertion. This ensures that a load on the housing-external connection contact does not cause an impermissible reduction of the contact force. 
   Preferably, a latch connection is provided for the mechanical fixation of the housing-external connection contact. This makes it especially easy for the buyer to assemble it. 
   In another especially preferred embodiment of the invention, the simulation switch, in addition to the electromagnetic release device, has a thermal excess-current release device for releasing the closed switching contact with an excess current that flows through it. Due to this measure, the simulation switch can be used as a conventional excess-current circuit breaker and also as a simulation switch. Furthermore, a simulation switch that has been augmented by this functional feature offers the possibility of remote release with a control current, which allows the switch to be opened even before reaching the excess current that is normally needed for the release. Such a simulation switch can then advantageously also be used in actual airplanes in which an error condition is detected by means of additional error diagnostic means, even before the excess current is reached. For example, when a microprocessor-operated control means is used, switching off is possible even before the critical excess current is reached. Such a circuit breaker can be advantageous especially for use in systems that allow an error analysis and a recognition of an error condition even before critical states that places a burden on the system are reached. 
   For this purpose, the switching contacts are preferably associated with connection contacts that are electrically separated from the connection contacts of the electromagnetic release device. An excess-current circuit breaker configured in this manner then has four connection contacts and entails two release devices that are independent of each other and that can possibly respond to different errors. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a further elucidation of the invention, reference is made to the embodiments depicted in the drawings. The following are shown: 
     FIG.  1 —a simulation switch according to the invention in a schematic diagram that illustrates the essential functions, 
     FIG.  2 —a simulation switch in an overall perspective view, 
     FIG.  3 —a longitudinal section of the simulation switch according to  FIG. 2  with closed switching contacts, 
     FIG.  4 —the simulation switch according to  FIG. 3  in the released state, 
     FIG.  5 —an exploded view of the electromagnetic release device of the simulation switch, 
     FIGS.  6  and  7 —an alternative embodiment with pluggable connection contacts in the closed and opened states, respectively, 
     FIG.  8 —an exploded view of the release device of this alternative embodiment, 
     FIG.  9 —the latching of the pluggable connection contacts in the housing of the simulation switch, 
     FIG.  10 —a simulation switch having pluggable connection contacts, in which the protective diode is connected in series to the relay of the electromagnetic release device, 
     FIG.  11 —another embodiment of a simulation switch according to the invention with a laterally positioned electromagnetic release device, and 
     FIG.  12 —a simulation switch in which the switching contacts can be released with an excess current as well as using the electromagnetic release device. 
   

   DETAILED DESCRIPTION 
   According to  FIG. 1 , a simulation switch according to the invention comprises a first and a second stationary switching contact  2  and  3  respectively as well as a movable switching contact (contact bridge)  4 . The movable switching contact  4  is mounted in a housing  6 —only indicated symbolically in the drawing—so as to pivot around a pivoting axis  8  and so as to be mechanically coupled via a switching mechanism (switching lock)  9  to an actuation element  10 , which is a rocker switch in this embodiment. 
   The movable switching contact  4  in the embodiment is configured as a contact bridge that bridges the stationary switching contacts  2 ,  3 . The stationary switching contacts  2 ,  3  are electrically connected to housing-external connection contacts  200 ,  300 . Instead of using a contact bridge as the movable switching contact  4 , it is fundamentally also possible to movably mount one or both of the switching contacts that are directly contacted with the connection contacts  200 ,  300 . 
   The movable switching contact  4  is operatively connected to a latching mechanism  12 , shown in the schematic diagram, by way of example, as a pivoting bar  13  that holds the switching contacts  2 ,  3 ,  4  in the closed position against the action of a first spring  14 , depicted symbolically as a tension spring in the schematic diagram of the figure. For this purpose, under the action of a second spring  16 , for example, shown as a pressure spring, the bar  13  latches with the movable switching contact  4  when the latter is in contact with the stationary switching contacts  2 ,  3  and bridges the switching segment between these switching contacts  2 ,  3 . 
   The bar  13 , in turn, is operatively connected to an electromagnetic release device  20 , with which said bar can be swiveled, for example, against the action of the second spring  16 , so that the latching mechanism  12  of the movable switching contact  4  is unlocked and it opens or is released by the action of the spring force exerted by the tension spring  14 , at the same time releasing the actuation element  10  (position indicated by a broken line). 
   For this purpose, the electromagnetic release device  20  comprises a relay  22  whose pull armature  24  is non-positively connected to the bar  13 . When a control current i is applied to the coil  26  of the relay  22 , the pull armature  24  is attracted, the latching mechanism  12  between the movable switching contact  4  and the bar  13  is unlocked and the contact is opened. The coil  26  is electrically connected in series to the switching segment formed by the switching contacts  2 ,  3 ,  4 , so that the control circuit for the relay  22  is automatically interrupted when the contact is opened. A protective diode  28  is connected in parallel or in series (indicated by a broken line) to the coil  26 . This imparts polarity to the relay, i.e. it can only be operated in one current direction. 
   As shown in  FIG. 2 , in a simulation switch according to an embodiment of the invention, a pushbutton  101  is provided as the actuation element  10 . The pushbutton  101  is inserted into a guide sleeve  102  that is provided with an external thread and that concurrently serves to attach the simulation switch to a control panel. The face  103  of the pushbutton  101  is provided with circular depression  104  that serves as a writing surface for an adhesive label indicating a desired rated current strength that is to be simulated. 
   The housing  6  preferably consists of two housing halves  6   a  and  6   b  made of thermoplastic material. The housing-external connection contacts  200 ,  300 —one of which is connected to the coil and the other to one of the switching contacts and which are configured as wire-wrap connections in this embodiment—project from the housing  6 . 
     FIG. 3  shows the simulation switch in the closed state, i.e. the pushbutton  101  is pushed in and the movable switching contact  4  is pressed with its contact piece  140  against the stationary switching contacts  2 ,  3 , whereby in the figure, the contact piece  120  of the approximately U-shaped first stationary switching contact  2  is covered by the contact piece  130  of the second stationary switching contact  3 . 
   The switching mechanism  9  shown in the embodiment is identical to the switching mechanism of the excess-current circuit breaker disclosed in German Utility Model Nos. 89 04 065 and 89 04 064, where it is explained in depth in terms of its structure and mode of operation. 
   A latching lever  32  that holds the movable switching contact  4  in the closed position serves as the latch  12 . The latching lever  32  is associated with a releasing lever  34  which, when actuated, causes the latching lever  32  to pivot and the switching contacts  2 ,  3 ,  4  and thus the switching segment between the switching contacts to open. 
   In order to actuate the releasing lever  34 , unlike with the excess-current circuit breaker disclosed in the above-mentioned utility models, the pull armature  24  of the relay  22  is provided instead of a bimetal. For this purpose, the releasing lever  34  has a fork-shaped free end  34   a  that faces away from the latching lever  32  and that engages in a ring-shaped recess  38  on the essentially cylindrical pull armature  24 . The releasing lever  34  is held in place by means of lateral bearing journals  40  so as to pivot in the corresponding bearing lugs  42  of the housing  6 . 
   In the figure, it can also be seen that the winding of the coil  26  is connected via the protective diode  28  to the U-shaped first stationary switching contact  2  and is thus connected in series to the switching segment. In the switched-on state, the pull armature  24  is then under the influence of a pressure spring  46  in the starting position and leans against a housing-internal stop surface  47 . In this starting position, the releasing lever  34  does not engage the latching lever  32 . In this position, a small current in the milli-ampere range can flow between the connection contacts  200  and  300  which, although not sufficient for the release, allows the control electronics to ascertain the switching state (closed or open contact). 
   If an adequately large control current i flows through the winding of the coil  26 , then according to  FIG. 4 , the pull armature  24  is pulled against the action of the pressure spring  46  into the inside of the coil  26 , causing the releasing lever  34  to pivot around the pivoting axis that is defined by the bearing journals  40  perpendicular to the drawing plane. With its free end  34   b  associated with the latching lever  32 , the releasing lever  34  causes the latching lever  32  to pivot, unlocking the switching lock of the switching mechanism in the manner described in the utility models referenced above. As a result, the movable switching contact  4  moves away from the stationary switching contacts  2 ,  3  and the pushbutton  101  pops out. 
   The state shown in  FIG. 4  does not depict the final state but rather a state during the opening of the contacts. Once the switching contacts  2 ,  3 ,  4  are opened, the relay  22  becomes current-free and the pull armature  24  returns to its starting position so that the releasing lever  34  likewise pivots back to its starting position shown in  FIG. 3 . 
   The switching mechanism explained in depth in the utility models involves a release procedure, i.e. the connection made by the movable switching contact  4  between the stationary switching contacts  2 ,  3  is also interrupted when the pushbutton  101  is held pressed down. 
     FIG. 5  shows the functional parts of the electromagnetic release device  20  in an exploded view. The relay  22  comprises a coil holder  47  onto which a U-shaped magnet yoke  48  has been slipped. The releasing lever  34 , whose free end  34   a  is fork-shaped, consists of a punched curved part onto which the bearing journals  40  are shaped in one piece. The pressure spring  46  on which the pull armature  24  is mounted is inserted into a hollow-cylindrical guide borehole  50  in the lengthwise direction of the coil holder  47 . The figure also shows that the second stationary switching contact  3  and the associated housing-external connection contact  300  are made in one piece. Likewise depicted is the U-shaped design of the first stationary switching contact which is connected to the protective diode  28  and whose contact piece  120  in the assembled state is arranged in one plane with the contact piece  130  of the second stationary switching contact  3 . 
   The alternative embodiment according to  FIG. 6  has a stationary switching contact  3   a  whose free end  52  facing away from the contact piece  130   a  is mounted in a recess  56  inside the housing  6 . The switching contact  3   a  is clamped in the housing  6  between a support journal  54  of the inner wall of the recess  56 , said journal being shaped onto the housing  6 . For this purpose, its free end  52  is provided with an L-shaped angled support foot  58  that rests in the recess  56 . In the area of the recess  56 , the free end  52  of the stationary switching contact  3   a  has a projecting spring element  60 , in the example a spiral spring, which projects into the recess  56  and which, when the switching contact  2   a  is fixed inside the recess  56 , can be moved against the spring force. 
   An insertion channel  62  opens up into the recess  56  and a housing-external connection contact  300   a  with its internal contact part  302  is inserted into said channel, whereby the spring element  60  presses against said part, thereby establishing an electric contact between the housing-external connection contact  300   a  and the stationary switching contact  3   a . The contact force F between the spring element  60  and the internal contact part  302  of the connection contact  300   a  acts parallel to the drawing plane and perpendicular to the direction of insertion  64  or to the lengthwise direction of the insertion channel  62 . Consequently, a mechanical load on the external contact part  304  of the connection contact  300   a  in this insertion or introduction direction  64  has no effect on the contacting since the contact force F acts perpendicular to the direction of insertion. Since the internal contact part  302  lies against the inner wall due to the staggered arrangement of the insertion channel  62 , which is narrower across from the recess  56 , as well as due to the action of the spring element  60 , a perpendicular load of the connection contact  300   a  leads either to an increase of the contact force F or leaves it practically unaffected. 
   For purposes of mechanical fixation in the housing  6 , the connection contact  300   a  is provided with catch recesses that engage with catch lugs that are arranged correspondingly in the housing  6 . 
   In a similar manner, the protective diode  28  and the winding of the coil  26  are contacted on the identically designed housing-external connection contact  200   a  with a contact element  66  that is likewise mounted in a recess  56  having the same shape. Here, in the area of the recess  56 , the contact element  66  is identical to the free end  52  of the switching contact  2   a  and it is electrically contacted in the same manner with the internal contact part  202 . With its free end  67 , the contact element  66  is connected to a connection contact of the protective diode  28 . In this embodiment, the protective diode  28  is connected in parallel to the winding of the coil  26 . For this purpose, the connection ends of the coil winding are contacted to a connection tab of the contact element  66  or to another connection contact of the protective diode  28 . 
   The figure also shows that different embodiments A, B, C can be provided as housing-external connection contacts whose external contact parts  204 ,  304  are designed differently and that are subsequently inserted into the simulation switch that was delivered without connection contacts, that is to say, only by the user as a function of his/her requirements. 
     FIG. 7  shows the simulation switch according to  FIG. 6  in the released state, whereby in this embodiment, the movable switching contact  4   a  is pivoted away in an upwards movement. 
   The exploded view according to  FIG. 8  shows the second stationary switching contact  3   a  and the contact element  66 —which is connected via the protective diode  28  to the first stationary switching contact  2   a —as well as the spring element  60  that is shaped in one piece onto each of them. The contact element  66  is provided with a contact tongue  66   a  that is soldered to a connection contact of the protective diode  28 . Another connection tab  66   b  is provided for soldering to the connection contact of the coil winding. 
   The housing-external connection contacts  200   a ,  300   a  are provided on their narrow sides with catch recesses  68  that engage in corresponding projections (catch lugs) in the housing  6  and that secure the connection contacts  302   a ,  303   a  in interaction with stop shoulders  69  against axial shifting. The contact force F exerted by the spring element  60  acts perpendicular to the direction of insertion  64  and is uncoupled from the mechanical holding force. 
   According to  FIG. 9 , on the side walls of the insertion channel  62 , there are catch lugs  70  that are provided with a gliding bevel  72  in the direction of insertion  64 . The connection contact  200   a  ( 300   a ) is tapered in the direction of insertion  64  and likewise provided with a slanted segment  74  that slides on the gliding bevel  72  when the connection contact  200   a  ( 300   a ) is inserted into the insertion channel  62  and that pushes the side walls of the insertion channel  62  apart. In the end position of the connection contact  200   a ,  300   a , the catch lugs  70  snap into the recesses  68  so that it is no longer possible for the connection contact  200   a ,  300   a  to be pulled out or to fall out. In this position, the stop shoulder  69  rests on the edge of the insertion channel  62  so that the connection contact  200   a ,  300   a  is secured in both directions against axial shifting. 
   In the embodiment according to  FIG. 10 , in the case of a simulation switch having pluggable housing-external connection contacts  200   a ,  300   a , the protective diode  28  is connected in series to the coil winding. For this purpose, the contact tongue  66   a  ( FIG. 8 ) of the contact element  66  has been left out so that only its connection tabs are connected to the coil winding. 
   According to  FIG. 11 , the simulation switch is provided with an electromagnetic release device  20  as well as with a bimetal-controlled thermal excess-current release device  80  of the type disclosed, for example, in German Utility Model Nos. 89 04 065 and 89 04 064. The electromagnetic release device  20  and the thermal excess-current release device  80  are electrically uncoupled from each other. 
   For this purpose, the simulation switch is provided with two additional connection contacts  82  and  84  ( FIG. 12 ) to which the switching contacts  2 ,  3  are connected. The electromagnetic release device  20  is mechanically connected in series to the thermal excess-current release device  80 , whereby between the releasing lever  34  anchored on the pull armature  24  and the latching lever  32 , there is a second releasing lever  86  that is coupled to a bimetal  88  that serves as a thermal releasing element. In this embodiment, the simulation switch can be used as an actual excess-current circuit breaker with remote release, i.e. the release is effectuated either via an excess current I that flows through the connection contacts  80 ,  82  or via a control current i that flows to the coil  26 . 
   In order for the switching state of the simulation switch to be ascertained, the switch is provided with an additional signal contact  90  that is actuated by a signal contact lever  92  that is operatively connected to the switching mechanism  9 . 
   In the embodiment according to  FIG. 11 , the electromagnetic release device  20  is arranged next to the switching mechanism  9 . For this purpose, the electromagnetic release device  20  is coupled to an L-shaped releasing lever  340  that is pivotally mounted at the intersection of its legs in a bearing trough  342 . In the figure, this releasing lever  340  is shown in its two end positions. 
   Such an arrangement is especially advantageous when the available installation depth is limited and it is not possible to install a simulation switch in which the electromagnetic release device  20  is arranged below the switching mechanism  9 , as shown in  FIGS. 1 to 10  and  FIG. 12 . 
   The spatial arrangement of the electromagnetic release device  20  shown in the embodiment with reference to a simulation switch having an additional excess-current release device  80  can also fundamentally be used for a simulation switch without an excess-current release device  80 .