Device for scanning a switching device, vehicle and method for scanning a switching device

Abstract

A device (110) for scanning a switching device (115) having a first (155) and a second terminal (160), the first terminal (155) being connected to a predetermined electrical potential, the device (110) comprising: a terminal (125) for connection to the second terminal (160) of the switching device (115); a first current source (130); a second current source (135); a control device (145) for connecting the first or the second current source (135) to the terminal (125); and an evaluation device (140) for determining a position of the switching device (115) as a function of a voltage applied to the terminal (125) while the first current source (130) is connected to the terminal (125);wherein the evaluation device (140) is configured to determine a defect if a circuit connected to the terminal (125) is outside a predetermined voltage range while the second current source (135) is connected to the terminal (125);

Description

[0001] The present invention relates to scanning and checking a switching device, in particular on board a vehicle.

[0002] A vehicle includes an electrical load that can be controlled depending on the positions of one or more switching devices. For example, an electrical adjustment of a seat can be controlled depending on the position of a first switching device, which can be manually operated by a user, and the position of a second switching device, which is operated in a final position of the seat. The seat is only adjusted if the user requests an adjustment that does not extend beyond the final position.

[0003] DE 10 2008 044 115 A1 discloses a switching element, a bus switching system, a control unit and a method for detecting switch positions of a plurality of switching elements.

[0004] DE 10 2006 033 705 B3 describes a circuit arrangement and a method for checking a switch position, as well as a use of the circuit arrangement. DE 103 47 979 A1 discloses a diagnosable switch arrangement.

[0005] A switching device comprises two terminals, one of which is connected to a predetermined potential, such as ground. The other terminal is connected to a current source, such as a pull-up resistor. If the voltage applied to the switching device is high, the switching device can be determined to be open; if the voltage is low, the switching device can be determined to be closed. However, if an electrical connection in the switching device breaks, becomes high-resistance, or an undesirable electrical connection exists between one of its terminals and a potential on board the vehicle, the position of the switching device can be incorrectly determined.

[0006] It was proposed to use a diagnostic-capable switching device with integrated resistors that would externally display different resistance values, both greater than zero and less than infinity, depending on the switch position. To reliably determine the switch position, a wetting voltage must be applied to the switch, which would potentially break down any impurity layer resistance at its contacts.

[0007] One object of the invention is to provide an improved technique for testing various switching devices for switch positions and defects. The invention achieves this object by means of the subject matter of the independent claims. Subclaims specify preferred embodiments.

[0008] According to a first aspect of the present invention, a device for sensing a switching device having a first and a second terminal, the first terminal being connected to a predetermined electrical potential, comprises a terminal for connection to the second terminal of the switching device; a first current source; a second current source; a control device for connecting the first or the second current source to the terminal; and an evaluation device for determining a position of the switching device as a function of a voltage applied to the terminal while the first current source is connected to the terminal; the frit voltage is also provided by the first current source; the evaluation device is configured to determine a defect if a circuit applied to the terminal lies outside a predetermined voltage range while the second current source is connected to the terminal.

[0009] The device can be operated with different voltages. In particular, it can be used on board a vehicle whose electrical system can have one of several possible voltages, for example 12 V, 24 V, or 48 V. A power source can essentially comprise a resistor to a predetermined electrical potential. The electrical potential can be provided by a voltage regulator and is usually below the operating or on-board voltage. Activating and deactivating, or switching on and off, a power source can be done by means of a semiconductor, for example a transistor, or by means of an electromechanical switch. The device can be constructed simply and without external active components.Advantageously, both power sources can be switched off or disconnected from the terminal to deactivate the switching device, for example in the event of detection of a low-resistance short circuit.

[0010] If both power sources are disconnected from the terminal, high-resistance short circuits at the terminal can also be diagnosed.

[0011] The current sources are preferably configured to provide different currents. To this end, the current sources can operate with different predetermined electrical potentials. Under otherwise identical conditions, different voltages are thus established at the switching device, depending on which current source is connected to it.

[0012] Advantageously, the device according to the invention can be used both for simple switching devices comprising only one switch and for diagnostic-capable switching devices which additionally have two resistors, of which only one (switch open) or both are passed through by current (switch closed), depending on the switch position.

[0013] In this context, the parallel resistor enables open-load diagnostics, i.e. detection of an interrupted or insufficient electrical connection between the switching device and the terminal.

[0014] The series resistor serves to protect the switch (current limiting) in the event of a short circuit in the switching device.

[0015] The device according to the invention does not require any additional active components. A switching device and its electrical connection do not need to be modified in order to replace a simple switching device with a diagnostic-capable switching device.

[0016] The device can detect various defects. For example, it can be determined that a connection between the switch and the terminal or the predetermined potential is interrupted. Furthermore, it can be determined that an electrical connection exists between the terminal and a predetermined potential. The potential can, in particular, be a used operating or on-board voltage or zero.

[0017] The switching device may comprise a switch with two terminals connected in pairs to the terminals of the switching device. Such a switching device is also called a simple switching device.

[0018] A switch mentioned herein relates to any type of mechanically operated component that has two electrically conductive contacts that are mechanically connected to one another in a first switch position and mechanically separated from one another by an isolating gap in a second switch position. The contacts are connected in pairs to terminals of the switch, so that the terminals are electrically connected to one another or electrically separated from one another depending on the switch position. A switch can also be designed as a push-button or interrupter. In the present case, a single-pole normally open contact or a single-pole normally open contact is assumed. A switch can be bistable, for example in the form of a toggle switch, a rocker switch, a step switch, a latching switch, a multiple switch, or a selector switch.The switch can also be monostable and return to a rest position after removal of an actuation, for example in the form of a push button or a key.

[0019] The switching device can comprise a switch and two resistors, one of which is located between a terminal of the switching device and a terminal of the switch, and the other between the terminals of the switch or between the terminals of the switching device. Such a switching device is also called a diagnosable switching device. Due to the resistors, the resistance effective between the terminals of the switching device can be less than infinity when the switch is open and greater than zero when the switch is closed. Both effective resistance values ​​can be predetermined by dimensioning the resistors. Depending on the switch position, one of two predetermined voltages can be set at a current source, with both voltages differing from zero and from an operating voltage of the current source.If the voltage applied to the power source deviates from one of the predetermined voltages by more than a predetermined amount, a defect may be present.

[0020] If the switch position is known, a defect can be identified if the voltage applied to the switching device lies outside a voltage range defined by the predetermined voltage and the predetermined value. If the switch position is unknown, a defect can be identified if the voltage lies outside two voltage windows, each of which is defined with respect to a switch position.

[0021] The switch position determination can be periodically interrupted by the detection of a defect. For example, approximately 99% of the time, the switch position can be determined using the current from the first power source, and approximately 1% of the time, a defect can be determined using the current from the second power source. A defect check can be performed, for example, every approximately 1 second or every approximately 10 seconds. Other intervals are also possible. Both power sources can also be disconnected from the terminal to detect defects.

[0022] A first current provided by the first current source is preferably sufficiently large to clean the switch contacts of the switch. The second current provided by the second current source is preferably smaller than the first current, so that a switch of the switching device is predominantly operated with a sufficient voltage to reliably make contact and clean itself ("fritting").

[0023] A first current provided by the first current source can be predetermined depending on the internal structure of the switching device. For determining the first current, a distinction can be made, in particular, between a simple switching device and a diagnosable switching device. Optionally, variants of diagnosable switching devices can be provided for connection to the terminal. These variants differ in the dimensioning of the resistors they comprise. The larger the resistor connected in series with the switch, the larger the first current can be selected to achieve a predetermined frit voltage.

[0024] The device is preferably configured to control a load depending on a specific switch position or depending on a specific defect. The load can comprise, for example, a resistive, capacitive, or inductive load, or a combination thereof. If no defect is present, the load can be controlled depending on the specific switch position. If a defect has been diagnosed, the load can be controlled to safe operation, which typically involves shutting down the load.

[0025] The switching device and the load can be mounted on board a vehicle. The device is preferably also designed for use on board a vehicle, in particular on board a motor vehicle. The motor vehicle can comprise an electrical system with a predetermined on-board voltage, from which one or both power sources can be operated and with respect to which the predetermined potential for the switching device can be determined. Optionally, two different predetermined voltages are generated based on the on-board voltage and can each be fed to the terminal via a resistor. The load can also be powered from the on-board electrical system.

[0026] According to a further aspect of the present invention, a vehicle comprises a device described herein and a switching device mentioned herein. Additionally, a consumer mentioned herein may be provided on board the vehicle.

[0027] According to yet another aspect of the present invention, a method for scanning a switching device having a first and a second terminal, the first terminal being connected to a predetermined electrical potential, comprises the steps of connecting the second terminal of the switching device to a first current source; determining a position of the switching device as a function of a voltage that occurs at the first current source; connecting the second terminal of the switching device to a second current source; and determining a defect as a function of a voltage that occurs at the second current source.

[0028] The method can be carried out partially or completely by means of a device described herein and, in particular, controlled by means of a control device included in the device. For this purpose, the control device can comprise a programmable microcomputer or microcontroller, and the method can be in the form of a computer program product with program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the device, or vice versa.

[0029] The invention will now be described in more detail with reference to the accompanying figures, in which: Fig. 1 a system; Fig. 2 voltages at a terminal of a device; and Fig. 3 shows a flow diagram of a procedure.

[0030] Fig. 1 shows a system 100, which is preferably mounted on board a vehicle 105. The vehicle 105 preferably comprises a motor vehicle, in particular a motorcycle, a passenger car, a truck, or a bus. The system 100 comprises a device 110, a switching device 115, and optionally a consumer 120 (not shown). Differently constructed switching devices 115 can be used, of which Fig. 1, three are shown as examples, designated S1, S2, and S3. A terminal 125 is provided for connecting the device 110 to a switching device 115. The terminal 125 can be designed as an electrical contact point, in particular as a soldered or plug-in connection. The switching devices 115 are shown connected to the terminal 125 with dashed lines to indicate the alternative nature of the connections.

[0031] The device 110 comprises a first current source 130 configured to provide a first current I1, a second current source 135 configured to provide a second current I2, and an evaluation device 140 configured to evaluate a voltage present at the terminal 125. The currents I1 and I2 of the current sources 130, 135 are different; for example, it is assumed here that I1 is greater than I2. A current source 130, 135 can be formed by a resistor connected to a predetermined voltage. The current sources 130, 135 can be operated at different predetermined voltages, which can be generated from the on-board voltage. Similarly, a voltage source whose current is limited to a predetermined level can also be used.

[0032] In addition, a control device 145 is preferably provided to control the current sources 125, 130 and the evaluation device 140. The evaluation device 140 is configured to sample a voltage applied to the terminal 125 and compare it with one or more different threshold values. For this purpose, the analog voltage can be converted into a digital value. Based on a comparison, a switch position of the switching device 115 connected to the terminal 125 or a defect in the area of ​​the switching device 115 can be determined. A determination result of the evaluation device 140 can be provided internally or externally via an interface 150. In one embodiment, the load 120 is connected to the interface 140 for control purposes. In another embodiment, another device can further process the result of the interface 150.

[0033] The device 110 can also comprise a plurality of terminals 125, each configured for connection to a switching device 115. The device 110 can be configured to apply an individually suitable first or second current to each switching device 115 while determining a voltage applied to the terminal 125. Current sources 130, 135 or the evaluation device 140 can be used sequentially to treat a plurality of switching devices 115. Additional current sources 130, 135 can be provided to provide additional currents.

[0034] Switching device S1 is referred to as simple, and switching devices S2 and S3 are referred to as diagnostic-capable. All switching devices 115 each comprise a first terminal 155 and a second terminal 160. The first terminal 155 can be connected to a predetermined potential, in particular ground, and the second terminal 160 is configured for connection to terminal 125. Furthermore, each switching device 115 comprises a switch 165 that converts a mechanical actuation into an electrical property.

[0035] In the simple switching device S1, terminals of switch 165 are connected in pairs to terminals 155 and 160. No further components are provided.

[0036] The diagnostic-capable switching devices S2 each also incorporate a first resistor 170 and a second resistor 175. In the switching device S2, the first resistor 170 is connected in parallel to contacts of switch 165. One terminal of switch 165 is connected to the first terminal 155, and the other terminal is connected to the second terminal 160 via the second resistor 175. If switch 165 is open, the sum of the resistors 170 and 175 acts at terminals 155 and 160; if switch 165 is closed, only the second resistor 175 acts.

[0037] In switching device S3, the first resistor 170 is connected in parallel to terminals 155, 160. One terminal of switch 165 is connected to the first terminal 155, and the other terminal is connected to the second terminal 160 via the second resistor 175. If switch 165 is open, only the first resistor 170 acts at terminals 155, 160; if switch 165 is closed, a parallel circuit consisting of the first resistor 170 and the second resistor 175 acts.

[0038] It is proposed to determine a switch position of a switch 165 of a switching device 115 by causing a first current to flow through the switching device 115 using the first current source 130. The position-dependent effective resistance of the switching device 115 causes a voltage to be established at the terminal 125, which indicates the switch position. The evaluation device 140 can compare the voltage with one or more threshold values ​​and determine the switch position therefrom.

[0039] The first current is dimensioned such that the switch 165 of the switching device 115 operates correctly and ideally cleans itself due to a flowing fritting current. The first current can be determined depending on the switching device 115 used.

[0040] It is further proposed to determine a defect in the region of a switching device 115 in a similar manner, but using a second current different from the first current by means of the second current source 135. Since the currents differ from one another, the voltages determined at terminal 125 must also differ from one another if no defect exists and the switch position of the switching device 115 has not been changed between the determinations.

[0041] Fig. 2 shows exemplary voltages at terminal 125 of device 110. In a left-hand area, voltages are shown when the first current source 130 is active, and in a right-hand area, voltages are shown when the second current source 135 is active.

[0042] A first voltage 205 denotes a predetermined potential, which can correspond to an operating voltage of an on-board electrical system or a potential derived therefrom. For the first power source 130, the first voltage 205 can be approximately 12 V or approximately 24 V, for example, while for the second power source 135, the first voltage 205 can be approximately 10 V or approximately 22 V. A second voltage 210 denotes a low potential of the on-board electrical system, which is typically connected to a ground of the vehicle 105.

[0043] If a simple switching device 115 is used, the voltage at terminal 125 can correspond to either the first voltage 205 or the second voltage 210, depending on the switch position. When comparing the voltage applied to terminal 125 with a predetermined voltage, a predetermined tolerance can be included.

[0044] A third voltage 215 and a fourth voltage 220 can correspond to different switch positions of a diagnosable switching device 115. A voltage divider is formed by respective effective resistors 170, 175 in the switching device 115 and a resistor comprised by the current source 130, 135, so that a voltage is established at terminal 125 that has a predetermined ratio to the voltage at which the current source 130, 135 is operated. The current sources 130 and 135 use different voltages, so that the voltages 215 and 220 are also different. If the ratios are the same for both current sources 130, 135, it can be assumed that there is no defect. This also applies to a simple switching device 115.If the same voltage is detected at terminal 125 when activating different current sources 130, 135, a defect can be identified, which may be caused by a short circuit between terminal 125 and a fixed potential. Such a voltage is shown in . Fig. 2 is symbolized by a dashed line. A defect can also be determined if the determined voltage differs sufficiently from one of the predetermined voltages, even for just one of the current sources.

[0045] Fig. 3 shows a flowchart of a method 300 that can be applied to a device 110 and executed in particular by means of the control device 145.

[0046] In a step 305, the first current source 130 can be activated and the second current source 135 can be deactivated. Subsequently, in a step 310, the voltage occurring at terminal 125 can be determined. The voltage can be compared with a predetermined threshold value in a step 315. The threshold value can be predetermined depending on the first current used and a design of the switching device 115. Different threshold values ​​can be predetermined for a simple switching device 115 and for a diagnosable switching device 115. Different threshold values ​​can also be provided for switching devices 115 with different internal designs or with differently dimensioned built-in resistors 170, 175. Preferably, in step 315, only a determination is made as to whether the voltage present at terminal 125 is above or below the determined threshold value.From this, a first or second switch position of the switching device 115 can be deduced in a step 320. Optionally, the load 120 can be controlled depending on the determined switch position.

[0047] Steps 305 to 320 can be executed multiple times before branching to a step 325, in which the first current source 130 is deactivated and the second current source 135 is activated. Subsequently, in a step 330, the voltage established at terminal 125 can be determined. In a step 335, threshold values ​​for a switching device 115 used can be determined, and in a step 335, the determined voltage can be compared with a specific threshold value.

[0048] If a previously determined switch position of the switching device 115 is taken into account, an expected voltage can be determined from which the voltage at the terminal should not deviate by more than a predetermined amount if no defect is present. In one embodiment, a lower and an upper threshold value can be determined based on the predetermined amount, between which the voltage at the terminal 125 lies if no defect is present. If the switch position is unknown, two voltage windows can be determined, whereby no defect is present if the voltage lies within one of the voltage windows. The determination of whether a defect is present can be made in a step 340. If a defect has been determined, the possible defect can also be determined based on a deviation of the determined voltage from the expected voltage or the voltage window.

[0049] A message about the identified defect can be provided at interface 150. Optionally, load 120 can be placed in a safe state. Furthermore, both power sources 130, 135 can be shut down to deactivate switching device 115. Defects in the switching device can also be detected when both power sources are shut down. The voltage at the terminal resulting from the defect overlaps with valid states of the switching device when power source 130 or 135 is connected. If further scanning of switching device 115 is required, method 300 can return to step 305 or 325 and run through again. Reference symbol 100 systems 105 vehicles 110 Device 115 Switching device 120 consumers 125 Terminal 130 first current source (first current I1) 135 second current source (second current I2) 140 Evaluation device 145 Control device 150 interface 155 first connection 160 second connection 165 switches 170 first resistance 175 second resistance 205 first voltage (operating voltage) 210 second voltage (diagnostic voltage) 215 third voltage 220 fourth voltage 300 procedures 305 provide first electricity 310 Determine voltage at the terminal 315 Apply thresholds for assigned switching device 320 Determine switch position 325 provide second power 330 Determine voltage at the terminal 335 Apply thresholds for assigned switching device 340 Determine defect

Claims

[1] Device (110) for sensing a switching device (115) having a first (155) and a second terminal (160), the first terminal (155) being connected to a predetermined electrical potential, the device (110) comprising: a terminal (125) for connection to the second terminal (160) of the switching device (115); a first current source (130); a second current source (135); a control device (145) for connecting the first or the second current source (135) to the terminal (125); and an evaluation device (140) for determining a position of the switching device (115) as a function of a voltage applied to the terminal (125) while the first current source (130) is connected to the terminal (125);wherein the evaluation device (140) is configured to determine a defect if a circuit connected to the terminal (125) is outside a predetermined voltage range while the second current source (135) is connected to the terminal (125); [2] The device (110) of claim 1, wherein the switching device (115) comprises a switch (165) having two terminals connected in pairs to the terminals (155, 160) of the switching device (115). [3] Device (110) according to claim 2, wherein the switching device (115) comprises a switch (165) and two resistors, one of which is located between a terminal (155, 160) of the switching device (115) and a terminal of the switch (165) and the other between the terminals of the switch (165) or between the terminals (155, 160) of the switching device (115). [4] Device (110) according to one of the preceding claims, wherein the voltage range is determined as a function of an effective electrical resistance by the switching device (115). [5] Device (110) according to claim 4, wherein the effective resistance is determined as a function of a specific switch position (165). [6] Device (110) according to one of the preceding claims, wherein the determination of the switch position (165) is periodically interrupted by the determination of the defect. [7] Device (110) according to one of the preceding claims, wherein a first current provided by the first current source (130) is sufficiently large to clean switching contacts of the switch (165). [8] Device (110) according to one of the preceding claims, wherein a first current provided by the first current source (130) is determined depending on an internal structure of the switching device (115). [9] Device (110) according to one of the preceding claims, wherein the device (110) is configured to control a consumer depending on the determined switch position (165) or depending on a determined defect. [10] Device (110) according to claim 9, wherein the switching device (115) and the consumer (120) are mounted on board a vehicle (105). [11] Vehicle (105) comprising a device (110) according to one of claims 9 or 10 and the switching device (115) and the consumer (120). [12] Method (300) for scanning a switching device (115) having a first (155) and a second terminal (160), wherein the first terminal (155) is connected to a predetermined electrical potential, the method comprising the following steps: connecting (305) the second terminal (160) of the switching device (115) to a first current source (130); determining (320) a position of the switching device (115) as a function of a voltage that is established at the first current source (130); connecting (325) the second terminal (160) of the switching device (115) to a second current source (135); and determining (340) a defect as a function of a voltage that is established at the second current source (135).

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