Device for switching an electrical consumer circuit operated with high voltage from a voltage source

Description

[0001] The invention relates to a device for switching an electrical consumer circuit operated with high voltage from a voltage source according to the preamble of claim 1.

[0002] Pollutant emissions from combustion engines have been taken increasingly seriously in recent years. To reduce these emissions, the use of electric motors in the mobile sector is being strongly promoted. It is assumed that the demand for electricity can increasingly be met by renewable energies.

[0003] Replacing combustion engines with electric motors usually requires large currents and high voltages. Therefore, a large number of electrical storage cells, currently mostly lithium-ion batteries, are connected in series.

[0004] The individual cells typically operate at a voltage of approximately 3.6 V. Electric motors, especially those used in motor vehicles, require a voltage of more than 300 V, so more than 100 such cells must be interconnected accordingly. Certain vehicles today even operate at voltages of approximately 700 V.

[0005] Since the capacity of energy storage devices that can be carried in an electrically powered vehicle is relatively low, it is important to ensure that no discharge occurs via the load circuit during downtime. To achieve this, the load circuit must be completely disconnected from the energy storage device.

[0006] This isn't normally a problem, as switching occurs when the vehicle is stationary and there is no load. Typically, a contactor is used for this, which holds the contacts in the closed position using magnetic force. Depending on the position in which the contactor is installed, vehicles are always subject to situations while driving in which strong acceleration (for example, when driving over potholes) acts on the contactor. This can cause the contacts to open while a load is present. This then leads to arcing and the consequent burning of the contacts. Such switches therefore do not have a long service life and must be replaced frequently.

[0007] Circuit breakers for the low-voltage range are known from DE 10 2006 029788 A1 and DE 10 2006 015502 A1. These circuit breakers have a contact pin and at least two contact sockets. The contact pin is movable along its longitudinal axis. In this way, electrical contact can be created between the first contact socket and at least two contact sockets by moving the contact pin.

[0008] The invention is based on the object of designing a device for switching an electrical load circuit operated with high voltage from a voltage source in such a way that both a connection and a disconnection between the load circuit and the voltage source can be achieved in a simple and safe manner. Furthermore, the unintentional opening of the switching device is to be prevented, thus significantly extending its service life.

[0009] The object is achieved according to the invention by a device for switching an electrical consumer circuit operated with high voltage from a voltage source, having the features of claim 1. By virtue of the fact that a contact bolt is connected to the push rod of a linear drive and the contact bolt can be brought into at least two positions in a switch housing, the switch housing having at least two contact rings on its inner wall, one of which is connected to a voltage source and the other to the consumer circuit, a switching device is created which can be switched back and forth between at least two states, wherein the two states cannot be inadvertently changed, even under extreme conditions during travel, regardless of the installation position in the means of transport. Since all intended switching operations take place without a load, the formation of an arc is reliably prevented.

[0010] High voltage here means a voltage of several hundred volts. The linear actuator is powered by a standard low-voltage on-board battery (usually 12 V).

[0011] The invention is applicable to all electrically powered means of transport. Means of transport are defined here as all devices for transporting people and / or goods on land, water, and in the air. "Electrically powered" refers to all means of transport that are at least partially electrically powered. This also includes so-called hybrid vehicles, which are powered partly by an electric motor and partly by an internal combustion engine.

[0012] A linear actuator is any actuator that generates a linear movement. This includes all rotating actuators that actuate a threaded push rod, as well as piezo actuators or solenoids that directly generate a linear movement. The only requirement is that the actuators operate with high forces and are also equipped with a high holding force.

[0013] Further details and advantages of the invention emerge from the subclaims.

[0014] Preferably, the contact bolt is only connected to the load circuit in the open position and to the load circuit and the voltage source in the closed position. This enables precisely defined switching states that can be achieved over a relatively short displacement path. Only the conductive connection between the load circuit and the voltage source needs to be interrupted or made. A powerful and reliable drive is required to move the contact bolt in the switch housing. The linear drive is therefore designed as a stepper motor and the rotor has a threaded nut for moving the push rod, which is designed as a threaded rod. The push rod is secured against rotation and the threaded nut is secured against rotation relative to the rotor. A stepper motor is now an inexpensive component that can be controlled very precisely.Usually, only initialization in one switching position is necessary, so position sensors for the other switching positions can largely be dispensed with. The thread transmission allows the push rod to be moved with great force by a relatively small motor. The holding force is also enormous. A stepper motor is also secure against simple tampering, as a specific phase sequence is required for control.

[0015] For safety reasons, the switching device is designed to disconnect the load circuit from the voltage source if the low operating voltage for the linear drive fails, making orderly shutdown of the load circuit impossible. For this purpose, the threaded nut is mounted concentrically to the rotation axis, and the push rod is preloaded toward the contact bolt's open position when the contact bolt is in the closed position. The threaded nut is held in an operating position by a locking element.

[0016] The locking element must be designed in such a way that, in the event of a failure of the voltage required for the orderly operation of the switching device, it moves into a position that allows the threaded nut to be moved into an inoperative position. The locking element is therefore advantageously designed as a solenoid, which is in the locked position when voltage is applied and moves to the released position when the applied voltage is switched off. If the operating voltage for the orderly switching off of the switching device fails, the solenoid also drops out and releases the threaded nut, which then moves together with the preloaded push rod and brings the contact bolt in the switch housing into the open position. To avoid an arc, a strong preload force must be generated, which accelerates the push rod greatly and moves the contact bolt quickly.

[0017] The load circuit should be disconnected from the voltage source not only in the event of a power failure for the switching device, but also if the vehicle is involved in an accident. This is the only way to prevent the high voltages supplied to the load circuit from being transferred to components that come into contact with people or possibly with fuel or other highly flammable substances. It is therefore particularly advantageous to have a gas generator connected to the switch housing, which is linked to an impact sensor via a control system. The gas pressure generated by the gas generator develops a high force, allowing the contact pin to move quickly into the open position. This high speed helps to prevent an arc.But the fact that the gas flows around at least one contact pin when the connection is broken also prevents the formation of an arc (spark quenching).

[0018] To enable the contact pin to move from the closed position to the open position using the gas pressure generated by the gas generator, it would be possible to provide the push rod and the threaded nut with a relatively steep thread. Since this would require the rotor to rotate, the system exhibits a certain inertia, and the shutdown process would take a longer period of time. Therefore, an advantageous design incorporates a predetermined breaking point. In this way, the contact pin can move very quickly into the open position in the event of an accident without rotating the rotor.

[0019] The predetermined breaking point can, for example, be provided directly in the push rod. For this purpose, two concentric push rod sections could be connected by compression. As soon as a large force acts on the contact pin, the two push rod sections slide into each other. However, it is particularly advantageous if the contact pin is designed as a hollow cylinder closed on one side, and the predetermined breaking point has a star-shaped connection between the push rod and the open side of the hollow cylinder. With this design, there are no mixed states; it is clearly visible whether the predetermined breaking point is intact or broken.

[0020] Advantageously, a third contact ring is provided on the inner wall of the switch housing, which is connected to earth or ground. This makes it possible to connect the load circuit to ground when the switching device is in the open position. For this case, a resistor is preferably provided between the third contact ring and ground, allowing a slow discharge of the charge after switching off.

[0021] Preferably, however, the third contact ring is only intended for use in the event of an accident, so that in the normal open position of the switching device there is no conductive connection between the contact bolt and the third contact ring. In order not to endanger people after an accident, the charge from the consumer circuit should be discharged as quickly as possible after such an event. In this design, no resistance may be provided between the third contact ring and ground. When the gas generator is ignited, the contact bolt is moved into an emergency position in which it connects the consumer circuit to earth or ground. In this emergency position, the contact bolt connects the contact ring, which is connected to the consumer circuit, with the third contact ring. It is of no importance if welding should occur due to a high current, since the switching device must be replaced after an accident anyway.

[0022] The switching device according to the invention can also be provided at both terminals of the consumer circuit, so that after an accident the consumer circuit is connected to earth with both its positive pole and its negative pole.

[0023] Further details and advantages of the invention will become apparent from the description of an embodiment, which is explained in detail with reference to the drawing.

[0024] It shows: Fig. 1 a schematic sectional view of an embodiment according to the invention with the switch in the open position, Fig. 2 the embodiment from Fig. 1 with the switch in the closed position, Fig. 3, which in the Figures 1 and 2 shown embodiment after an emergency shutdown and Fig. 4 the embodiment after activation of the gas generator, for example after an accident.

[0025] The Fig. 1The embodiment shown has a main switch 1 which is switched via a linear drive 2. The linear drive 2 has a stator 14 mounted stationary in the drive housing 13 and a rotor 15 rotatably mounted within the stator 14. Concentric with the axis of rotation of the rotor 15, a threaded nut 16 is provided, which is connected to the rotor 15 in a rotationally fixed manner, but is mounted displaceably along the axis of rotation of the rotor 15.

[0026] Also concentric with the axis of rotation of the rotor 15 is a push rod 11, which is mounted in such a way that it can be moved along the axis of rotation, but does not participate in the rotation of the rotor 15 and the threaded nut 16 connected to it in a rotationally fixed manner. The push rod 11 is provided with an external thread in the area of ​​the threaded nut 16, which is in operative contact with the internal thread of the threaded nut 16. At its end opposite the main switch 1, the push rod 11 is provided with a push rod flange 20. This projects into a spring housing 3, which is fixedly mounted to the drive housing 13. Between the push rod flange 20 and the inner wall of the spring housing 3 facing the drive housing 13 is the spring 21, which slightly preloads the push rod flange 20 against the inner wall of the spring housing 3 opposite the drive housing.

[0027] Connected to the threaded nut 16 is the round nut flange 17, which is located in a corresponding recess in the drive housing 13. A solenoid 18 is attached to the drive housing 13 next to the recess for the nut flange 17. This solenoid 18 is provided with a locking lever 19, which, when the solenoid 18 is energized, locks the nut flange 17 and thus prevents the threaded nut 16 from shifting in the direction of the rotational axis of the rotor 15.

[0028] The main switch 1 has a permanently mounted switch housing 4 and a contact pin 6 slidably mounted within the switch housing 4. The contact pin 6 is designed as a hollow cylinder, which is closed at its end face facing away from the push rod 11. At its open side, it is connected to the push rod 11 via a predetermined breaking point 12.

[0029] The predetermined breaking point 12 is not explicitly shown in the drawing, but a possible embodiment will be explained below. The predetermined breaking point 12 is preferably designed as a separate component. It has an inner ring that is connected to the push rod 11. It also has an outer ring that is connected to the open edge of the hollow cylinder of the contact pin 6. The inner and outer rings are connected to each other via three beams. The beams are designed such that they tear off when a predetermined force acts between the inner and outer rings. The beams therefore form the actual predetermined breaking point.

[0030] The switch housing 4 has three annular recesses in its inner wall into which the contact rings 5 ​​are inserted. The left contact ring is in contact with a terminal 7 to the voltage source, the middle contact ring with a terminal 8 to the load circuit, and the right contact ring with a terminal 9 to ground. The contact pin 6 is designed to electrically connect two contact rings to each other.

[0031] A gas generator 10 is attached to the side of the switch housing 4 opposite the drive 2. This gas generator 10 is connected to the interior of the switch housing 4 via openings not shown here. Preferably, gas outlet openings are also provided between the left and middle contact rings, close to the middle contact ring, but these are also not shown here.

[0032] In the following, the different positions of the device according to the invention in the Figures 1 to 4The function will be described in detail using the example of an electric vehicle. It is assumed that the electric vehicle has a 12 V on-board battery and a voltage source with an output voltage of approximately 400 V. The voltage source supplies the consumer circuit, in this case one or more electric motors.

[0033] In Fig. 1The switching device is shown in the open position. In this position, the contact bolt 6 only contacts connection 8 to the consumer circuit. Therefore, no voltage is applied to the consumer circuit. The ignition key is already in the ignition lock, so that the solenoid 18 is powered by the 12 V on-board battery. The locking lever 19 is therefore in the locked position, in which the threaded nut 16 is prevented from moving along the axis of rotation of the rotor 15 by the nut flange 17. After turning the ignition key, the linear drive 2 is also powered by the 12 V on-board battery. By rotating the rotor 15 together with the threaded nut 16 in the opening direction, the push rod 11 is moved to the left.

[0034] The position after completion of this movement is in Fig. 2shown. The main switch 1 is in the closed position. The contact pin 6, connected to the push rod 11 via the predetermined breaking point 12, has reached the very left side of the switch housing 4. It establishes an electrically conductive connection between terminal 7 to the voltage source and terminal 8 to the load circuit.

[0035] The push rod flange 20 has also participated in the movement of the push rod 11 and is located to the left of its initial position. The spring 21 has been tensioned. The push rod 11 with the contact bolt 6 and the threaded nut 16 are now preloaded in the opening direction of the main switch 1. However, the locking lever 19 and the nut flange 17 prevent a corresponding opening movement of the push rod 11, contact bolt 6, and threaded nut 16.

[0036] When the electric vehicle is parked, the linear motor 2 is energized when the ignition key is turned back so that the rotor 15 rotates in the opening direction. The push rod 11 and the contact pin 6 are then returned to the positions shown in Fig. 1 shown position. The main switch 1 is back in its open position.

[0037] When the ignition key is removed from the ignition lock, the connection between the solenoid 18 and the 12 V on-board battery is interrupted, so that the locking lever 19 is moved into a position that is not Fig. 1 shown release position. However, this has no influence on the position of threaded nut 16 and push rod 11, since the push rod flange 20 already rests against the inner wall of the spring housing 3 and cannot be moved further to the left.

[0038] If the 12 V on-board battery is discharged during operation of the electric vehicle (see Fig. 2) fail for any reason, it would no longer be possible to separate the voltage source from the consumer circuit, since the linear actuator 2 can no longer be powered. The spring 21 and the solenoid 18 are provided for this situation. Based on the Fig. 2 In the operating position shown, if the 12 V on-board voltage fails, the solenoid 18 drops out and the locking lever 19 moves into its release position.

[0039] As a result, the force of the spring 21 now acts on the push rod 11 via the push rod flange 20 and moves it, together with the threaded nut 16 and the contact bolt 6, to the right until the push rod flange 20 again rests against the inner wall of the spring housing 3. The main switch 1 is now located as in Fig. 1 in the open position. The connection between the voltage source and the consumer circuit is therefore interrupted. The position after a failure of the 12 V on-board voltage is in Fig. 3 shown.

[0040] As soon as a repair is carried out, the electric vehicle can be put back into operation. When the ignition key is inserted into the ignition lock, the locking lever 19 cannot be moved into its locked position because it is prevented from doing so by the nut flange 17. The control system (not shown here) therefore energizes the linear drive 2 in the opening direction. Since the push rod 11 cannot be moved any further to the right, the threaded nut 16 is pressed back to the left into the rotor 15. After the threaded nut 16 has reached its normal position (as shown in the Figures 1, 2 and 4 ) the locking lever 19 can now move back into its locking position and the electric vehicle is ready to start again (see Fig. 1 ).

[0041] If the electric vehicle is involved in an accident, the consumer circuit should be disconnected from the voltage source very quickly. Again, starting from the operating position in Fig. 2is ignited by an impact sensor and the control of the gas generator 10. The resulting gas flows into the switch housing 4 and builds up a high pressure there. This breaks the predetermined breaking point 12 and the contact pin 6 is pushed to the right until it rests against the side wall of the switch housing 4 facing the linear drive 2. This position is in Fig. 4 shown. To prevent the internal pressure from causing the switch housing 4 to explode, gas outlet openings (not shown here) are provided next to the central contact ring.

[0042] The contact bolt 6 represents Fig. 4a connection between terminal 8 to the consumer circuit and terminal 9 to ground. In this way, in the event of an accident, not only can the consumer circuit be disconnected from the voltage source, but it can also be discharged. Ideally, a switching device according to the invention is provided between the positive terminal of the voltage source and the consumer circuit, and between the negative terminal of the voltage source and the consumer circuit. In this case, in the event of an accident, both the negative terminal and the positive terminal of the consumer circuit are connected to ground.

[0043] To restart the system, the switching device must be replaced after the gas generator 10 has been triggered.

[0044] However, the application of the invention is not limited to means of transportation; it can also be used in stationary systems. For example, it may be useful to isolate a photovoltaic system from the consumer circuit with inverter and / or power storage using one or two of the switching devices according to the invention. List of reference symbols:

[0045] 1 Main switch 2 Linear drive 3 Spring housing 4 Switch housing 5 Contact rings 6 Contact bolt 7 Connection to voltage source 8 Connection to consumer circuit 9 Connection to ground 10 Gas generator 11 Push rod 12 Predetermined breaking point 13 Drive housing 14 Stator 15 Rotor 16 Hexagon nut 17 Round nut flange 18 Solenoid 19 Locking lever 20 Push rod flange 21 Spring

Claims

1. Device for the switching of an electrical consumer load circuit, operated at high voltage from a voltage source, in an electrically-driven means of locomotion, by a drive operated at low voltage, wherein a contact bolt (6) is connected to the push rod (11) of a linear drive (2), and the contact bolt (6) can be brought into at least two positions in a switching housing (4), wherein the switching housing (4) has at least two contact rings (5) on its inner wall, of which one is connected to the voltage source (7), and the other is connected to the consumer load circuit (8), wherein the linear drive (2) is designed as a stepper motor, characterised in that the rotor (15) has a threaded nut (16) for the movement of the push rod (11), designed in the form of a threaded rod, wherein the push rod (11) is secured against rotation, and the threaded nut (16) is secured against rotation, relative to the rotor (15).

2. Device in accordance with Claim 1, characterised in that in the open position, the contact bolt (6) is only connected to the consumer load circuit (8), and in the closed position, is connected to the consumer load circuit (8) and the voltage source (7).

3. Device in accordance with Claim 2, characterised in that the threaded nut (16) is mounted such that it can be displaced concentrically with respect to the axis of rotation, and, in the closed position of the contact bolt (6), the push rod (11) is pre-loaded in the direction of the open position of the contact bolt (6), wherein the threaded nut (16) is held in an operating position by a blocking element (18).

4. Device in accordance with Claim 3, characterised in that the blocking element is designed in the form of a solenoid (18), which, when voltage is applied, is located in the blocking position, and, when the applied voltage is switched off, moves into the release position.

5. Device in accordance with one of the Claims 1 to 4, characterised in that a gas generator (10) is connected to the switching housing (4), which is connected to an impact sensor via a control unit.

6. Device in accordance with one of the Claims 1 to 5, characterised in that the contact bolt (6) has a predetermined breaking point (12) with respect to the push rod (11).

7. Device in accordance with Claim 6, characterised in that the contact bolt (6) is designed in the form of a hollow cylinder, closed on one side, and the predetermined breaking point (12) has a star-shaped connection between the push rod (11) and the open side of the hollow cylinder.

8. Device in accordance with one of the Claims 1 to 7, characterised in that a third contact ring (5) is provided on the inner wall of the switching housing (4), which is connected to earth or ground (9).

9. Device in accordance with one of the Claims 6 to 8, characterised in that the contact bolt (6) is moved into an emergency position when the gas generator (10) is ignited, in which position it connects the consumer load circuit (8) to earth or ground (9).