Voltage encoding of switching states of a control device with redundancy

Abstract

The invention relates to a method for voltage encoding of switching states of a switching unit (12) of a control device (74), wherein the switching unit (12) has at least three switching elements (14), wherein the control device (74) has a number of output terminals (28, 30) reduced by one according to the number of switching elements (14), wherein the control device (74) individually assigns exactly one combination of voltage levels at the output terminals (28, 30) to each switched-on switching state of each switching element (14).According to the invention, the second switching element connections (18) are electrically coupled to each output connection (28, 30) by means of a resistor network (32), wherein the control device (74) has at least one redundancy switching element (60) which is mechanically coupled to one of the at least three switching elements (14) and is electrically coupled to a redundancy output connection (62) of the control device (74).

Description

[0001] The invention relates to a control device, a vehicle control system, a motor vehicle and a method according to the preambles of the independent claims.

[0002] Control devices, vehicle control systems, motor vehicles, and processes are used, for example, in motor vehicles to implement a wide variety of functionalities during the intended operation of the vehicle. For instance, it is common to install a turn signal indicator by means of a lever on the steering column, particularly near the steering wheel (also called a stick switch), which allows the driver to indicate an intended change of direction by manually operating it. The vehicle has corresponding lights, usually designed as turn signals, which can be activated by operating the lever on the steering column. Another corresponding lever on the steering column can also be used to control, for example, the operation of a windshield wiper system.

[0003] It is now common practice for the gear levers that actuate the corresponding switching elements to no longer directly control a specific drive unit or – in the case of the turn signal – a specific indicator light. Instead, it is now standard practice for the gear positions, which represent the respective switching states of the switching elements, to be electronically monitored. Depending on the electronically monitored switching state, the desired functionality is then activated by the vehicle's control system.

[0004] Control devices of this type are used, for example, in motor vehicles to control various vehicle functions. It is common practice, for instance, to integrate a control unit comprising several individual switches into a so-called steering column module for a motor vehicle. These individual switches are used, for example, to control a windshield wiper and washer system, a turn signal indicator, a high beam switch, a lighting system of the motor vehicle, and / or the like.

[0005] Electronic querying is generally performed by means of a control unit which, in addition to the switching elements, has one or more electronic components and is connected to a program-controlled computer unit of the vehicle control system. The control unit can implement voltage coding, which enables the computer unit to query the respective switching position of the switching elements based on a detected voltage and, accordingly, to control the desired functionality. For example, DE 10 2010 026 919 A1 discloses a method for detecting the switching position of a control unit of this generic type.

[0006] Even though this method has proven successful, there is still room for improvement. The circuit arrangement of DE 10 2010 026 919 A1 proves to be disadvantageous, among other reasons, because it requires the use of specific switching elements that can assume multiple switching positions. Furthermore, it is necessary to couple the switching elements not only with individual measuring resistors but also with individual switching resistors, meaning that all switching elements must be connected in a complex two-pole manner.

[0007] Furthermore, the circuit arrangement of DE 10 2010 026 919 A1 has the disadvantage that each switching element must be coupled to a corresponding input terminal of the computer unit. This allows the switching elements to operate independently of each other, so that the computer unit can evaluate any switching state. However, errors can occur during normal operation, for example, due to contamination of a contact or similar, causing the computer unit to incorrectly detect a switching position that the driver did not activate. With the circuit arrangement of DE 10 2010 026 919 A1, such errors can only be detected to a very limited extent. Furthermore, DE 10 2017 113 905 A1 discloses a circuit arrangement for evaluating at least two switching states of an actuating element, a method for operating a circuit arrangement, and a circuit arrangement itself.DE 10 2010 048 750 A1 further discloses a circuit arrangement for evaluating switching states. In addition, DE 10 2009 056 283 A1 discloses a switch and a circuit arrangement for evaluating at least two switching states. Finally, DE 10 2006 038 375 A1 discloses a circuit arrangement.

[0008] However, there are also safety-critical situations where only one state is permitted. In the automotive industry, these situations are considered within the context of so-called functional safety (FuSi) and are designated with an ASIL (Automotive Safety Integrity Level according to the ISO 26262:2011 standard "Road vehicles - Functional safety"). The safety requirement that only one valid state may be transmitted is implemented by the control unit. If multiple states are detected simultaneously, this can be recognized as a fault. The occurrence of a fault leads to a loss of function. This is highly detrimental to the intended use and – under certain circumstances – even dangerous.

[0009] The invention is based on the objective of improving the safety of a control device, a vehicle control system, a motor vehicle and a method of the generic type.

[0010] The invention proposes a control device, a vehicle control system, a motor vehicle and a method according to the independent claims as a solution.

[0011] With regard to a control device of the generic type, the invention particularly proposes that this device has an electrically coupling resistor network to each second switching element connection and each output connection in order to individually assign exactly one combination of voltage levels at the output connections to the respective switched-on switching state of a respective switching element, wherein the control device has at least one redundant switching element which is mechanically coupled to one of the at least three switching elements and has a first switching element connection for electrical connection to the electrical reference potential and a second switching element connection, wherein the second switching element connection of the redundant switching element is electrically coupled to a redundant output connection of the control device individually assigned to the redundant switching element for connection to the processing unit.

[0012] With regard to a generic vehicle control system, the invention proposes that the control device be designed according to the invention.

[0013] With regard to a motor vehicle of the type described, the invention specifically proposes that the vehicle control system be designed according to the invention.

[0014] With regard to a generic method, the invention particularly proposes that the second switching element terminals are electrically coupled to each output terminal by means of a resistor network in order to individually assign exactly one combination of voltage levels at the output terminals to the respective switched-on switching state of a respective switching element, wherein the control device has at least one redundant switching element which is mechanically coupled to one of the at least three switching elements and has a first switching element terminal for electrical connection to the electrical reference potential and a second switching element terminal, wherein the second switching element terminal of the redundant switching element is electrically coupled to a redundant output terminal of the control device individually assigned to the redundant switching element for connection to the processing unit.

[0015] The invention is based, among other things, on the idea that, in order to detect and rectify a fault—which may be caused, for example, by contamination of a contact in one of the switching elements, a broken contact spring, or the like—the intended function can be maintained despite the fault. Thanks to the redundant switching element and the correspondingly adapted control unit, it is possible not only to detect a fault but also to maintain functionality despite the fault. This means, for example, that when the shift lever on the steering column is manually operated to activate a turn signal function, the current operating state of the control unit and the switching state of the respective switching element can be verified by additionally evaluating a signal at the redundant output terminal.If an error occurs regarding the neutral position of the gearshift lever, so that two switching elements appear to be actuated, the actual actuation can still be determined by the user and thus the flashing function can be activated.

[0016] This can resolve any availability problem of the blinking function caused by the error, and the function can continue to be provided.

[0017] The switching elements can be combined in a switching unit as a single component, which is preferably part of the control device. The switching elements can be designed as electromechanical switching units, rotary switches, slide switches, in particular gear selectors, and / or the like. The invention thus makes it possible to cover safety-critical situations in which only one specific switching state is permitted.

[0018] The switching unit can be a compact, individually handled component, preferably comprising all switching elements. The switching elements have first switching element connections that can be electrically coupled to the electrical reference potential. For this purpose, the first switching element connections can be electrically interconnected, so that the switching unit only needs to provide a single external connection for linking to the reference potential. This significantly reduces the effort required for wiring and assembly, particularly compared to DE 10 2010 026 919 A1.Furthermore, this design allows for easy cascading if required, meaning that instead of just three switching elements and two output connections in the circuit arrangement, the number of switching elements and thus the number of input connections can be increased as needed, with the number of output connections also increasing simultaneously. The number of input connections is therefore typically one greater than the number of output connections.

[0019] The processing unit is preferably designed to match the number of output connections. For its intended function, the processing unit may include an electronic hardware circuit. Alternatively or additionally, the processing unit may also include a program-controlled computer unit that electrically connects to the corresponding output connections of the circuit arrangement. The processing unit may, for example, provide an analog-to-digital conversion for each output connection of the circuit arrangement. Analog-to-digital conversion can be provided for each output connection of the circuit arrangement. However, it may also be provided that the processing unit queries and processes the voltage levels provided by the output connections of the circuit arrangement using a multiplexing method. The processing unit may be provided, at least in part, by the vehicle control unit.

[0020] Because exactly one of the switching elements is always in an on state and all other switching elements are in an off state, the resistor network results in a unique combination of voltage levels at the output terminals for each switching state of the switching unit. This enables the processing unit to reliably determine the respective switching state of the control device, in particular the switching unit. At the same time, the invention allows the processing unit to reliably detect faulty states, for example, due to a contact fault in one of the switching elements. Such faults typically result in deviations in the voltage levels, enabling the processing unit not only to detect that a fault exists but also to isolate and correct it.The processing unit can then preferably be configured to send a corresponding error message to the higher-level vehicle control system, in particular the motor vehicle.

[0021] The switching elements of the switching unit can be designed as individual switching elements. However, it is also possible for the switching elements to be designed together as a single unit, for example, by using a multi-finger wiper as a contact medium, which establishes corresponding electrical contacts on the buttons of a circuit carrier depending on the wiper's position.

[0022] The at least one redundant switching element is preferably also designed as an electromechanical switching element. It can be designed in the same way as the other switching elements. For example, the redundant switching element can be mechanically coupled to at least the switching element for which redundancy is to be achieved. In principle, it is also possible to mechanically couple the redundant switching element to more than one switching element for which redundancy is to be achieved. The redundant output connection is assigned to the redundant switching element. If several redundant switching elements are provided, preferably each of the redundant switching elements has its own individual redundancy output connection. The at least one redundant switching element can, for example, be part of the switching unit.

[0023] It is further proposed that a first switching element be assigned to a home position, whereas the other switching elements are assigned to distinct operating positions, with the second switching element terminal of the first switching element being electrically coupled to the resistor network via an electrically actuated enabling switching element. The home position can, in particular, be a neutral position, a rest position without manual actuation, or the like, in which no function is activated. In the home position, the first switching element is in the on state, and all other switching elements are in the off state. The second switching element terminal of this switching element is electrically coupled to the resistor network via the electrically actuated enabling switching element.This makes it possible to couple this switching element to the resistor network depending on the switching state of the enabling switching element. Thus, it can be achieved that the first switching element is electrically isolated from the resistor network when the enabling switching element is off. When the enabling switching element is on, however, the first switching element is electrically connected to the resistor network. By evaluating a signal from the enabling switching element, a fault can be rectified, restoring the desired functionality.

[0024] The enabling switching element can be an electrically actuated electromechanical switching element such as a relay, contactor, or the like. However, the enabling switching element can also be an electronic switching element such as a transistor operating in switching mode, or the like. The switching operation of a transistor means that, in the on-state, a very low electrical resistance is provided between the terminals forming the switching path, allowing a high current flow at a very low residual voltage. In the off-state, the switching path of the transistor has a high resistance, meaning it provides a high electrical resistance, so that even at a high voltage applied to the switching path, there is essentially no current flow or only a very small, and in particular negligible, current flow. This differs from linear operation.

[0025] Furthermore, it is proposed that the resistor network has at least one supply terminal for connection to an electrical supply potential, wherein the resistor network has a series connection of at least two electrical resistors for each output terminal, wherein each series connection has a first and a second series connection, wherein the first series connection of each of the series connections is electrically coupled to exactly one of the respective output terminals, wherein the second series connections of at least two respective series connections are electrically coupled to each other via at least one coupling resistor, wherein a respective center connection of each of the series connections is electrically coupled to exactly one of the respective input terminals.and wherein exactly one of the input terminals is electrically coupled to at least one of the second series-connected terminals. Due to the special design of the resistor network with exactly one series connection for each output terminal consisting of at least two measuring resistors in conjunction with the coupling resistor, it is thus possible to ensure that a combination of voltage levels is present at the output terminals of the circuit arrangement, depending on the switching element or switching state of the switching unit that is currently switched on. The processing unit can therefore determine the switching state of the switching unit by evaluating the voltage levels at all output terminals.

[0026] The resistors in the resistor network can, in principle, all have the same resistance value. However, depending on requirements and design, it may also be intended that at least some of the resistors in the resistor network have different resistance values. This can be advantageous, for example, if the supply potential is very high or very low relative to the reference potential. Furthermore, the invention is not limited to the supply potential being applied at the supply terminal and the reference potential at the switching unit. In principle, this can of course also be reversed without affecting the function of the invention.

[0027] The invention utilizes the further concept that, for evaluating the voltage coding—that is, the voltage levels assigned to each switching state of the switching unit—not only a single input of a processing unit, such as the computer unit, is used, but that multiple connections of the processing unit can be used to access additional data or information, in particular additional redundancy. Thus, according to this embodiment of the invention, for example, with three switching elements of the control unit, the processing unit has at least two inputs that can be connected to the corresponding outputs of the control unit. The control unit provides, by means of the resistor network, a corresponding individual coding via voltage levels at the output connections of the control unit for each switching state of the switching elements.This allows each combination of voltage levels at the output terminals of the circuit arrangement to be individually assigned to a specific switching state of the switching unit. The state of the switching elements is determined by one of the switching elements being in the "on" state, while all other switching elements of the switching unit are in the "off" state. The switching elements of the control device are thus coupled to each other, so that only one of the switching elements can be in the "on" state at any given time. Such a control device is used, for example, to control turn signals in a motor vehicle, which are arranged on the steering column of the vehicle by means of a lever. However, this design is not limited to applications in motor vehicles.The control device can be implemented, for example, as a rotary switch or a linearly actuated control device. The switching elements can be electromechanical and actuated together by means of the switch lever. However, it is also possible for them to be electronic, such as transistors operating in switching mode.

[0028] According to a further development approach, it is proposed that each of the second series connection terminals be electrically coupled to the second switching element terminal of the redundant switching element via a respective diode. Thus, each input terminal is not directly coupled to the coupling resistor; instead, both terminals of the coupling resistor can be electrically connected to the corresponding input terminal via the diodes. Switching the switching element connected to this input terminal into the on state allows the coupling resistor to be deactivated.

[0029] Furthermore, it is proposed that the second switching element terminal of the first switching element be connected to the terminals of the coupling resistor via two diodes. This allows for a simple deactivation of the coupling resistor.

[0030] Furthermore, it is proposed that the resistor network includes a further series connection of at least two electrical resistors, which is connected between the second switching element terminal of the redundancy switching element and the supply terminal, wherein a center terminal of this series connection is electrically coupled to the redundancy output terminal. This allows for independent functionality with respect to the redundancy switching element.

[0031] According to a further embodiment, it is proposed that the redundancy switching element comprises at least one electromechanical or one electronic switching element. The redundancy switching element can be implemented as a cost-effective element.

[0032] The invention also includes the vehicle control system for the motor vehicle. The vehicle control system can include a data processing device or a processor circuit configured to carry out an embodiment of the method according to the invention. For this purpose, the processor circuit can include at least one microprocessor and / or at least one microcontroller and / or at least one FPGA (Field Programmable Gate Array) and / or at least one DSP (Digital Signal Processor). In particular, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an NPU (Neural Processing Unit) can be used as the microprocessor. Furthermore, the processor circuit can include program code configured to carry out the embodiment of the method according to the invention when executed by the processor circuit.The program code can be stored in a data memory of the processor device. The processor device can be based, for example, on at least one circuit board and / or on at least one SoC (System on Chip).

[0033] The invention also includes further developments of the method according to the invention, which have features already described in connection with the further developments of the control device according to the invention. For this reason, the corresponding further developments of the method according to the invention are not described again here.

[0034] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus or motorcycle. Instead of a motor vehicle, the invention can also be used in an aircraft, a watercraft, or another technical system.

[0035] The invention also includes combinations of the features of the described embodiments. The invention therefore also includes realizations that each exhibit a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

[0036] The following are exemplary embodiments of the invention described. This is illustrated by: Fig. 1 in a schematic side view a motor vehicle with a switching unit to which the switching arrangement is connected; Fig. 2 in a schematic circuit diagram representation a first embodiment for a circuit arrangement for the motor vehicle according to Fig. 1; Fig. 3 in a schematic circuit diagram representation a second embodiment for a circuit arrangement for the motor vehicle according to Fig. 1; Fig.4 in a schematic circuit diagram representation a third embodiment for a circuit arrangement for the motor vehicle according to Fig. 1; and Fig. 5 in a schematic circuit diagram, a fourth embodiment based on Fig. 4, in which a redundancy switching element and an enabling switching element are provided.

[0037] The exemplary embodiments described below are preferred embodiments of the invention. In these exemplary embodiments, the described components each represent individual features of the invention, which can be considered independently of one another and each further develops the invention independently. Therefore, the disclosure is intended to include combinations of features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0038] In the figures, identical reference symbols denote functionally equivalent elements.

[0039] Fig.Figure 1 shows a schematic side view of a motor vehicle 50. The motor vehicle 50 has a vehicle control unit 52 with a control device 74, which includes a switching unit 12 of the control device 74 for actuating a turn signal indicator of the motor vehicle 50 (not shown). The switching unit 12 is arranged in a steering column of the motor vehicle 50 (not shown) and can be manually actuated by the driver of the motor vehicle 50 by means of a lever that pivots about a steering axis to produce a flashing function as a turn signal indicator. The switching unit 12 is connected to a circuit arrangement 10 of the control device 74, which serves to voltage-code the switching states of the switching unit 12.The circuit arrangement 10 is in turn connected to a processing unit 54 of the control device 74, which determines the respective switching state of the switching unit 12 from detected voltage values ​​and provides the determined switching states for further use by the

[0040] Fig.Figure 2 shows a schematic circuit diagram of a first embodiment of a control device 74 with a switching unit 12 and a circuit arrangement 86 for voltage encoding of switching states of the switching unit 12, which in the present embodiment has exactly 3 switching elements 14. The switching elements 14 are configured to each assume an on and an off switching state. The switching unit 12 is configured such that at any given time only exactly one of the switching elements 14 assumes the on switching state and the other switching elements 14 assume the off switching state. The control device 74 is part of a direction indicator of the motor vehicle 50, which is arranged in a steering column of the motor vehicle 50 (not shown).

[0041] In the present embodiment, the circuit arrangement comprises a series connection of six electrical resistors R21 to R26, connected between a supply potential 36 and a reference potential 20. All switching elements 14 are connected to a central terminal 62 located between electrical resistors R24 and R25 via one of their terminals.

[0042] Resistors R21 and R22 provide a central terminal 90 to which another terminal of one of the switching elements 14 is connected. Resistors R22 and R23 provide a further central terminal 66 to which another terminal of a second switching element 14 is connected. Resistors R23 and R24 provide a further central terminal 68 to which another terminal of the third switching element 14 is connected. Resistors R25 and R26 provide a central terminal 70, which is connected via another resistor R27 to an output terminal 28 of the circuit arrangement 86. The output terminal 28 is connected to the processing unit 54. The output terminal 28 is also electrically coupled to the reference potential 20 via a capacitor C1.

[0043] As from Fig.As can be seen in Figure 2, the circuit arrangement 86 provides an electrical voltage at the output terminal 28, depending on which switching element 14 is switched on, due to a voltage divider function. The voltage value of this voltage can be individually assigned to the respective switching element 14. This achieves voltage coding, so that the switching unit 12 only needs to be coupled to the processing unit 54 via a single communication line.

[0044] In the present embodiment, the switching unit 12 and the switching elements 14 are electromechanical switching elements that can be manually operated by the driver of the motor vehicle 50 using the aforementioned operating lever. In this embodiment, it is provided that this is a flasher switch, with one of the switching elements being assigned to a left-hand flasher, one to a right-hand flasher, and one to the deactivated flasher function, i.e., a rest position.

[0045] The processing unit 54 can include a program-controlled computing unit, for example, a microcontroller, an ASIC, or the like, to evaluate the voltage signal provided at output terminal 28. For this purpose, the processing unit 54 can include one or more analog-to-digital converters.

[0046] Fig.Figure 3 shows a schematic circuit diagram illustrating a second embodiment for a control device 74 with a circuit arrangement 80 for voltage encoding of switching states of the switching unit 12, as already shown in Figure 3. Fig. 2 was explained, whereby in Fig. Figure 3 shows only two of the switching elements 14. A circuit corresponding to the two shown switching elements 14 can be provided for the third switching element 14. Accordingly, the processing unit 54 has three input connections, of which in the Fig. Only two are shown.

[0047] The control unit 74 according to Fig. 3 differs from the control device according to Fig.2. This is achieved by providing a separate input connection on the processing unit 54 for each of the switching elements 14. The switching elements 14, together with electrical resistors, form series circuits, as explained below. Each switching element 14, together with resistors R31 and R33, forms a series circuit connected between the supply potential 36 and the reference potential 20. A resistor R32 is connected to a center terminal 82, provided by the electrical resistors R31 and R33, and is electrically connected to the corresponding input terminal of the processing unit 54. The input of the processing unit 54 is further coupled to the electrical reference potential 20 via a capacitor C1.

[0048] Accordingly, the next of the switching elements 14, together with the electrical resistors R34 and R35, forms another series circuit connected between the electrical reference potential 20 and the supply potential 36. The electrical resistors R34 and R35 provide a center terminal 84 to which a resistor R36 is connected, which is further electrically connected to another input of the processing unit 54. This input is also coupled to the reference potential 20 via an electrical capacitor C2. Thus, a separate line is required for each switching element.

[0049] The switching elements 14 can be actuated independently of one another and can therefore be actuated both individually and together, so that any of these states is possible when evaluated by the processing unit 54. However, there may also be safety-critical situations in which only exactly one state may be assumed. These situations are particularly relevant in the automotive sector in the context of functional safety (FuSi) requirements. They can therefore be classified according to standard 26262 (Automotive Safety Integrity Level; ASIL).

[0050] The invention relates to the fact that each switching position of the switching unit 12 can be represented by a corresponding voltage value, which can be fed to the processing unit 54 for evaluation via an input terminal. In principle, such switching units can be used to control a wide variety of functions, particularly in motor vehicles. The switching elements 14 can, for example, also be used to control a windshield wiper and washer system, a high-beam switching system of the motor vehicle 50, or the like. As a turn signal, also called a turn signal, three states can be provided for the switching unit 12, namely a neutral state in which no flashing is activated, a "left flashing" state, and a "right flashing" state. These states are mutually exclusive, so that only one of these states is activated at any given time by means of the respective switching element 14.The neutral position is usually located between the other two states. The switching unit 12 can be configured to be actuated rotaryally or translationally.

[0051] Fig. Figure 4 shows a schematic circuit diagram of a third embodiment for a control device 74 with a circuit arrangement 10 for the motor vehicle 50 according to Fig. 1. This circuit arrangement 10 is also connected to the switching unit 12 on one side and to the processing unit 54 on the other. The control device 74 also serves to encode the switching states of the switching unit 12. The switching unit 12 is also configured here such that only one of the switching elements 14 is ever in the switched-on state, and the other switching elements 14 are each in the switched-off state.

[0052] The circuit arrangement 10 has an input terminal 22, 24, 26 for each of the switching elements 14 for electrical coupling with a respective second switching element terminal 18 of the respective switching element 14. The switching elements 14 also have respective first switching element terminals 16, which are configured for electrical connection to the electrical reference potential 20. In the present embodiment, the first switching element terminals 16 are connected together to the reference potential 20.

[0053] The circuit arrangement 10 has a reduced number of output terminals 28, 30 for connection to the processing unit 54, corresponding to the number of input terminals 22, 24, 26. In this case, two output terminals 28, 30 are provided. The control device 74 is further configured to individually assign exactly one combination of voltage levels at the output terminals 28, 30 to each activated switching state of a respective switching element 14 of the switching unit 12.

[0054] For this purpose, the circuit arrangement 10 includes a resistor network 32. The resistor network 32 couples each input terminal 22, 24, 26 to each output terminal 28, 30, the resistor network 32 having a supply terminal 34 for connecting to the supply potential 36. The resistor network 32 has, for each output terminal 28, 30, a series connection of two measuring resistors R4, R5 on one side and R8, R9 on the other.

[0055] Each of the series circuits has a first and a second series connection 38, 40, 42, 44. The first series connection 38, 42 of each series circuit is electrically coupled to exactly one of the respective output connections 28, 30. The second series connections 40, 44 are electrically coupled to each other via two coupling resistors R3, R7 connected in series. A center connection 46, 48 of each series circuit is electrically coupled to exactly one of the respective input connections 22, 26. The input connection 24, however, is electrically coupled to the second series connections 40, 44.

[0056] For this purpose, the resistor network 32 comprises two diodes D1 and D2. The anodes of diodes D1 and D2 are connected to the respective second series terminals 40 and 44. The cathodes of diodes D1 and D2 are electrically connected to the input terminal 24.

[0057] The first series connection terminals 38, 42 are furthermore electrically connected to the respective output terminals 28, 30 via respective output resistors R6, R10.

[0058] Furthermore, the supply connection 34 is electrically coupled via respective supply resistors R1, R2 to the respective first series connection 42, 38 or the respective output resistor R6, R10.

[0059] This control unit 74 not only reliably encodes the switching states of the switching unit 12 with respect to voltage, but also allows the processing unit 54 to detect faults or erroneous states. For example, in the event of an unintentional contact short circuit, e.g., due to foreign objects or the like, and an actuation direction towards the neutral position, an evaluation can be carried out via a circuit section comprising resistors R7 to R10 and diodes D1 and D2. Due to the fault, a different voltage encoding may occur at the output terminals 28, 30 than the predefined, individually assigned value.This proves particularly advantageous if the switching unit 12 is implemented by means of, for example, a multi-finger slider as a contact medium, wherein the multi-finger slider is attached to an operating lever and is moved along with the movement of the operating element in order to realize the different switching states of the switching unit 12 in this way.

[0060] The advantages of the circuit arrangement 10 according to the invention are shown in the following comparison. Fig. 4 compared to the circuit arrangement 86 according to Fig. 2 is evident.

[0061] Table 1 below shows different switching states of the switching unit 12, i.e., different states of the switching elements 14, with reference to a supply voltage of 5 V, which is applied between the supply potential 36 and the reference potential 20. Table 1 Switch S1 (left) Switch S2 (center) Switch S3 (right) Exit result open open open 5,00 V Mistake! open open closed 1,19 V No error (correct switch position) open closed open 2,22 V No error (correct switch position) open closed closed 0,92 V Mistake! closed open open 0,71 V No error (correct switch position) closed open closed 0,49 V Mistake! closed closed open 0,61 V Mistake! closed closed closed 0,44 V Mistake!

[0062] As can be seen from Table 1, the voltage values ​​at the output are sometimes very close together, making it difficult to reliably detect faulty or permissible states. For example, a permissible state occurs at 0.71 V, whereas a faulty state occurs at both 0.92 V and 0.61 V. This problem can be solved with circuit arrangement 10 according to... Fig. 4 can be avoided, as can be seen from Table 2 below.

[0063] Table 2 below shows that, in particular, switching states of the switching unit 12, in which more than one switching element 14 is in the switched-on state, can be better detected by the processing unit 54. Table 2 Switch S1 (left) Switch S2 (center) Switch S3 (right) Exit 1 Exit 2 result open open open 5,00 V 5,00 V Mistake! open open closed 2,50 V 4,08 V No error (correct switch position) open closed open 3,48 V 3,48 V No error (correct switch position) open closed closed 2,50 V 3,48 V Mistake! closed open open 4,08 V 2,50 V No error (correct switch position) closed open closed 2,50 V 2,50 V Mistake! closed closed open 3,48 V 2,50 V Mistake! closed closed closed 2,50 V 2,50 V Mistake!

[0064] As can be seen from Table 2, the faulty states are clearly distinguishable from the permissible states by the voltage coding.

[0065] Here too, the supply voltage is 5 V. Table 2 shows that two simultaneously switched-on switching elements 14 can be detected as errors by the processing unit 54. Therefore, the circuit arrangement 10 is suitable according to Fig. 4 especially for increased safety requirements, such as those levied in the field of automotive engineering.

[0066] Overall, the invention thus enables improved monitoring for faulty or disturbed conditions.

[0067] Fig. Figure 5 shows a schematic circuit diagram of a fourth embodiment of a control device 74 based on the embodiment according to Fig.4, in which a redundancy switching element 60 and an enabling switching element 72 are additionally provided. In the following, only the additions compared to the configuration according to are described. Fig. 4 explained.

[0068] The switching unit 10 additionally includes the redundant switching element 60. For this purpose, the circuit arrangement 10 has an input terminal 64 to which the second switching element terminal 18 of the redundant switching element 60 is connected. The input terminal 64 is connected to the supply potential 36 via a series connection of two electrical resistors 94, 92. A center terminal of this series connection is connected via an output resistor 88 to an output terminal 92 of the circuit arrangement 10, which is connected to the processing unit 54.

[0069] Furthermore, the enabling switching element 72 is connected between the input terminal 24 and the cathodes of diodes D1 and D2. In this case, the enabling switching element 72 is a relay, which is controlled by the processing unit 54 to assume a respective switching state.

[0070] As in the previous configuration according to Fig. As explained in section 4, such a system error can be detected, and a substitute response can be triggered in case of a fault. However, this leads to an availability problem; for example, the "blinking" function must not blink in case of a fault. In the design according to Fig.5. This problem can be solved with minimal effort and the function can continue to be provided. For this purpose, an additional contact, namely the redundancy switching element 60, is provided for the switching elements S1 and S2, and a suitable switching element, namely the enabling switching element 72, is also introduced into the electrical path of the switching element S3.

[0071] This implies that when state A or B is assumed, an additional, specifically self-contained, redundancy switching element is integrated and evaluated. Only if this redundancy switching element 60 is also activated is the corresponding state considered assumed and "true".

[0072] In the event that, for example, switching element S3 (neutral) and switching element S1 (state A) are closed, a fault condition would occur – as described above – and the backup reaction would be triggered. The redundant switching element S4 60 ensures that S1 has actually been actuated.

[0073] Nevertheless, switching element S3 remains actuated and the fault condition persists. By evaluating switching element S4, processing unit 54 can now use the enabling switching element 72, which is inserted into the electrical path from switching element S1, to deactivate this path and interrupt the electrical circuit of switching element S3. This eliminates the fault condition and allows the desired functionality to be implemented, resulting in increased availability.

[0074] The exemplary embodiments serve solely to illustrate the invention and are not intended to limit it.

Claims

[1] Control device (74) for a motor vehicle (50), comprising at least three switching elements (14), wherein each of the at least three switching elements (14) can be assigned a respective individual operating state of a motor vehicle function, wherein the switching elements (14) are configured to each assume an on and an off switching state, wherein the control device (74) is configured such that at any given time only exactly one of the at least three switching elements (14) assumes the on switching state and the other switching elements (14) each assume the off switching state, wherein the at least three switching elements (14) each have first switching element connections (16) for electrical connection to an electrical reference potential (20) and each have second switching element connections (18), wherein the control device (74) has a reduced number of output connections (28) corresponding to the number of switching elements (14), reduced by one.30) for connection to a processing unit (54), wherein the control device (74) is configured to electrically couple each of the second switching element terminals (18) with each of the output terminals (28, 30) and to individually assign exactly one combination of voltage levels at the output terminals (28, 30) to each switched-on switching state of a respective switching element (14), wherein the control device (74) has a resistor network (32) that electrically couples each second switching element terminal (18) with each output terminal (28, 30) in order to individually assign exactly one combination of voltage levels at the output terminals (28, 30) to each switched-on switching state of a respective switching element (14), wherein the control device (74) has at least one redundant switching element,which is mechanically coupled to one of the at least three switching elements (14) and has a first switching element connection (16) for electrical connection to the electrical reference potential (20) and a second switching element connection (18), wherein the second switching element connection (18) of the redundancy switching element (60) is electrically coupled to a redundancy output connection (62) of the control unit (74) individually assigned to the redundancy switching element (60) for connection to the processing unit (54). [2] Control device according to claim 1, characterized by, that a first of the switching elements (14) is assigned to an initial position, whereas the further switching elements (14) are assigned to respective different actuation positions, wherein the second switching element connection (18) of the first of the switching elements (14) is electrically coupled to the resistor network (32) via an electrically actuated enabling switching element (72). [3] Control device according to any one of the preceding claims, characterized by, that the resistor network (32) has at least one supply terminal (34) for connecting to an electrical supply potential (36), wherein the resistor network (32) has for each output terminal (28, 30) a respective series connection of at least two electrical resistors (R4, R5, R8, R9), wherein each series connection has a first and a second series connection terminal (38, 40, 42, 44), wherein the first series connection terminal (38, 42) of each of the series connections is electrically coupled to exactly one of the respective output terminals (28, 30), wherein the second series connections of (40, 44) of at least two respective series connections are electrically coupled to each other via at least one coupling resistor (R3, R7), wherein a respective center terminal (46, 48) of each of the series connections is electrically coupled to exactly one of the respective input terminals (22, 26),and wherein exactly one of the input terminals (24) is electrically coupled to at least one of the second series-connected terminals (40, 44). [4] Control device according to claim 3, characterized by , that each of the second series connection terminals (40, 44) is electrically coupled to the second switching element terminal (18) of the first switching element (14) via a respective diode (D1, D2). [5] Control device according to one of claims 3 or 4, characterized by , that the second switching element terminal (18) of the first of the switching elements (14) is connected via two diodes (D1, D2) to terminals of the coupling resistor (R3, R7). [6] Control device according to any one of the preceding claims, characterized by, that the resistor network (32) has a further series connection of at least two electrical resistors (92, 94) which is connected between the second switching element terminal (18) of the redundancy switching element (60) and the supply terminal (34), wherein a center terminal of this series connection is electrically coupled to the redundancy output terminal (62). [7] Control device according to any one of the preceding claims, characterized by , that the redundancy switching element (60) comprises at least one electromechanical or electronic switching element. [8] Vehicle control unit (52) for a motor vehicle (50), comprising a control unit (74) and a processing unit (54) connected to the control unit (74), characterized by that the control device (74) is designed according to one of the preceding claims. [9] Motor vehicle (50) with a vehicle control system (52), characterized by, that the vehicle control (52) is configured according to claim 8. [10] Method for voltage encoding of switching states of at least three switching elements (14) of a control device (74), wherein the at least three switching elements (14) each have first switching element terminals (16) for electrical connection to an electrical reference potential (20) and each have second switching element terminals (18), wherein the switching elements (14) are configured to each assume an on and an off switching state, wherein the control device (74) is configured such that at any given time only exactly one of the switching elements (14) assumes the on switching state and the other switching elements (14) each assume the off switching state,wherein the control device (74) for voltage encoding the switching states individually assigns to a switched-on switching state of a respective switching element (14) provided at the respective second switching element terminal (18) exactly one combination of voltage levels at output terminals (28, 30) of the control device (74) connected to a processing unit (54), wherein the control device (74) has a reduced number of output terminals (28, 30) for connection to a processing unit (54) corresponding to the number of switching elements (14), wherein the second switching element terminals (18) are electrically coupled to each output terminal (28, 30) by means of a resistor network (32) in order to individually assign to the respective switched-on switching state of a respective switching element (14) exactly one combination of voltage levels at the output terminals (28, 30),wherein the control device (74) has at least one redundancy switching element (60) which is mechanically coupled to one of the at least three switching elements (14) and has a first switching element connection (16) for electrical connection to the electrical reference potential (20) and a second switching element connection (18), wherein the second switching element connection (18) of the redundancy switching element (60) is electrically coupled to a redundancy output connection (62) of the control device (74) individually assigned to the redundancy switching element (60) for connection to the processing unit (54).

Images