Electronic control unit for a heating system

Abstract

Electronic control unit (10) for a heating device (100) of a vehicle seat, with - a printed circuit board (12) on which one or more heat sources (14a-14c) are arranged; - a printed circuit board temperature sensor (16) which is thermally coupled to at least one heat source (14a-14c) on the printed circuit board (12); and - at least one heating wire temperature sensor (18a, 18b) which is configured to be thermally coupled to a heating wire (102) of the heating device (100); characterized by a data processing device (22) which is configured to determine the temperature of the heating wire (102) on the basis of the temperature measurements (TS1, TS2, TS3) of the printed circuit board temperature sensor (16) and of the at least one heating wire temperature sensor (18a, 18b).

Description

[0001] The invention relates to an electronic control unit for a heating device of a vehicle seat, comprising a circuit board on which one or more heat sources are arranged, a circuit board temperature sensor which is thermally coupled to at least one heat source on the circuit board, and at least one heating wire temperature sensor which is configured to be thermally coupled to a heating wire of the heating device.

[0002] Furthermore, the invention relates to a heating device for a vehicle seat, comprising at least one heatable heating wire and an electronic control unit which is configured to control the heating of the heating wire and to monitor the temperature of the heating wire.

[0003] Furthermore, the invention relates to a vehicle seat with a seat cushion which provides a seating surface for the buttocks of a user, a backrest which provides a backrest surface for the back of the user, and a heating device which has one or more heating wires integrated into the seat cushion and / or the backrest and is configured to heat the seating surface and / or the backrest surface via the one or more heating wires.

[0004] Furthermore, the invention relates to a method for operating a heating device of a vehicle seat, comprising the steps of: detecting a temperature value by means of a printed circuit board temperature sensor of an electronic control unit of the heating device, wherein the printed circuit board temperature sensor is thermally coupled to at least one heat source on a printed circuit board of the electronic control unit, and detecting at least one temperature measurement value by means of at least one heating wire temperature sensor of the electronic control unit, which is thermally coupled to a heating wire of the heating device.

[0005] Modern vehicles typically feature seat heating, with heating wires controlled or regulated by an electronic control unit. During operation, the temperature of one or more sections of the heating wire is monitored to enable temperature-dependent control and / or regulation functions.

[0006] Temperature sensors, often designed as thermistors, are regularly used to measure the temperature. These thermistors can be, for example, NTC resistors (negative temperature coefficient resistors). The temperature sensors are typically located either directly on the heating element or within a heated area of ​​the vehicle seat.

[0007] The need for separate temperature sensors leads to an increased number of parts and thus to greater system complexity. This results in higher material costs, and the separate arrangement of the temperature sensors also leads to increased assembly effort. Overall, temperature measurement in heating devices that use one or more heating wires remains comparatively complex.

[0008] The object underlying the invention is therefore to simplify the detection of the temperature of a heating wire of a heating device of a vehicle seat without unduly impairing the detection accuracy.

[0009] The problem is solved by an electronic control unit of the type mentioned above, wherein the electronic control unit according to the invention has a data processing device which is configured to determine the temperature of the heating wire on the basis of the temperature measurements of the circuit board temperature sensor and the at least one heating wire temperature sensor.

[0010] The invention takes advantage of the fact that when using temperature sensors integrated into the electronic control unit, direct temperature measurement at the heating wire is not possible, as the corresponding temperature readings are distorted by one or more heat sources within the electronic control unit. The heating wire temperature sensor thus only determines the temperature of the heating wire approximately, since the integration of the heating wire temperature sensor into the electronic control unit distorts the temperature readings due to thermal influences. However, by taking into account the temperature readings from the circuit board temperature sensor, the measurement distortions caused by thermal influences can be compensated for, so that the temperature of the heating wire can be determined with sufficient accuracy.Integrating the circuit board temperature sensor and at least one heating wire temperature sensor into the electronic control unit significantly reduces system complexity. Furthermore, material costs and assembly effort are reduced.

[0011] Preferably, the data processing device for determining the temperature of the heating wire, based on the temperature readings from the printed circuit board temperature sensor and the at least one heating wire temperature sensor, incorporates one or more constants. These constants are preferably dependent on device and / or heating wire parameters and / or characterize the thermal conductivity of different areas of the electronic control unit. The one or more heat sources can be integrated circuits, in particular microcontrollers or heating element drivers. The one or more heat sources can include a low-side driver (LS circuit) and / or a high-side driver (HS circuit). The one or more heat sources can include one or more voltage regulators.

[0012] In a preferred embodiment of the electronic control unit according to the invention, the printed circuit board temperature sensor and / or the at least one hot-wire temperature sensor are each designed as a thermistor. The thermistor can be designed as an NTC resistor, i.e., as a positive temperature coefficient (PTC) thermistor. Alternatively or additionally, the printed circuit board temperature sensor and / or the at least one hot-wire temperature sensor are arranged on the printed circuit board. In particular, the printed circuit board temperature sensor and / or the at least one hot-wire temperature sensor are mounted on the printed circuit board. Alternatively or additionally, the printed circuit board temperature sensor and / or the at least one hot-wire temperature sensor are integrated or embedded in the printed circuit board or in an electronic component arranged on the printed circuit board. For example, the printed circuit board temperature sensor can be integrated into a microcontroller unit that is arranged on the printed circuit board.

[0013] In a further preferred embodiment of the electronic control unit according to the invention, the at least one heated-wire temperature sensor is thermally isolated from the one or more heat sources arranged on the circuit board and / or the circuit board temperature sensor. The thermal isolation of the at least one heated-wire temperature sensor is preferably achieved by a heat flow barrier on the circuit board. This thermal isolation of the heated-wire temperature sensor essentially prevents heat conduction through the circuit board body that would distort the temperature readings.

[0014] In another preferred embodiment of the electronic control unit according to the invention, the printed circuit board has at least one recess positioned between the at least one hot-wire temperature sensor and at least one heat source arranged on the printed circuit board or the printed circuit board temperature sensor itself. The at least one recess in the printed circuit board serves as a thermal barrier, thus essentially preventing heat conduction between the one or more heat sources or the printed circuit board temperature sensor and the at least one hot-wire temperature sensor. The recess can, for example, be L-shaped or arc-shaped and surround the hot-wire temperature sensor along a circumferential segment.

[0015] In another preferred embodiment, the electronic control unit according to the invention comprises a first heating wire temperature sensor and a second heating wire temperature sensor, each configured to be thermally coupled to a heating wire of the heating device, wherein the data processing unit is configured to determine a first heating wire temperature based on the temperature readings of the first heating wire temperature sensor and a second heating wire temperature based on the temperature readings of the second heating wire temperature sensor. In particular, the data processing unit is configured to disregard the temperature readings of the second heating wire temperature sensor when determining the first heating wire temperature.In particular, the data processing unit is configured to disregard the temperature readings of the first heating wire temperature sensor when determining the second heating wire temperature. Thus, the two heating wire temperatures are determined independently by the data processing unit. The temperature readings of the second heating wire temperature sensor do not correct or adjust the readings of the first heating wire temperature sensor. Furthermore, the temperature readings of the first heating wire temperature sensor do not correct or adjust the readings of the second heating wire temperature sensor. Due to the functional redundancy of the first and second heating wire temperature sensors, the criteria specified in ISO 26262 for Automotive Safety Integrity Levels (ASIL) A to D are met.For example, the data processing unit is configured to monitor and compare the temperature readings of the first and second heating wire temperature sensors. If the difference between these readings exceeds a predefined threshold, the data processing unit detects a defect or malfunction of one of the sensors. Provided that the two sensors do not fail simultaneously, effective and reliable functional monitoring can be implemented through this measurement comparison.

[0016] If the difference between the temperature readings of the first heating wire temperature sensor and the temperature readings of the second heating wire temperature sensor exceeds a predefined threshold, and the data processing unit detects a defect or malfunction of one heating wire temperature sensor, it is preferred that the higher temperature reading of the two heating wire temperature sensors be used as the basis for heating wire temperature control. This prevents the setting of an excessively high temperature at the heating wire, even in the event of a failure or malfunction of one heating wire temperature sensor. Ultimately, the set temperature on a heated backrest surface and / or the set temperature of a heated seat cushion will then be below the target temperature, while simultaneously preventing excessively high temperatures.

[0017] In an advantageous further development of the electronic control unit, the data processing unit is configured to determine a first heating wire temperature based on the temperature readings from the first heating wire temperature sensor and the circuit board temperature sensor, and a second heating wire temperature based on the temperature readings from the second heating wire temperature sensor and the circuit board temperature sensor. The first and second heating wire temperature sensors only provide approximate readings of the heating wire temperature. However, by taking into account the temperature readings from the circuit board temperature sensor, the measurement distortions caused by thermal influences can be factored out, resulting in the determination of two heating wire temperatures. In this way, redundant temperature measurement and thus also redundant temperature monitoring can be implemented.Heating systems can be classified as safety-relevant electrical or electronic systems in a vehicle. Such systems are regularly required to comply with one or more safety standards. To ensure the functional safety of such a system, these standards typically require redundant temperature monitoring to prevent risks and system failures in the event of a sensor failure or malfunction. In this case, such redundant monitoring of the heating wire temperature is achieved through the use of three different temperature sensors: two heating wire temperature sensors and one circuit board temperature sensor.

[0018] In a further development of the control unit according to the invention, the data processing unit is configured to perform a functional test of the temperature sensors during the start-up process of the control unit. As part of the functional test, the corrected temperature readings of the first heating wire temperature sensor, which already take into account the temperature readings of the printed circuit board temperature sensor, and the corrected temperature readings of the second heating wire temperature sensor, which also already take into account the temperature readings of the printed circuit board temperature sensor, are compared. The difference between the corrected temperature readings of the first and second heating wire temperature sensors after a start-up period following the start-up process must not fall outside a predefined tolerance range.A start-up time is factored in after the control unit starts up, as the correction of the temperature readings from the first and second heating wire temperature sensors via the temperature readings from the circuit board temperature sensor only provides reliable values ​​after a specific operating temperature range has been reached. If the difference between the corrected temperature readings of the first and second heating wire temperature sensors remains outside a tolerance range even after the start-up time has elapsed, a defect or malfunction is detected by the data processing unit.

[0019] Furthermore, a control device according to the invention is advantageous in which the first heated-wire temperature sensor, the second heated-wire temperature sensor, and the data processing unit are interconnected and connected to a voltage source in such a way that, in the event of a fault in the circuit, the data processing unit can detect the failure of both heated-wire temperature sensors. The fault can be a break in the circuit. Furthermore, the fault can also result not in a complete break in the respective circuit, but merely in a change in electrical resistance. The circuit can include lines for supplying power to the first heated-wire temperature sensor, the second heated-wire temperature sensor, and / or the data processing unit via the voltage source.Furthermore, the circuit can include lines for transmitting the measurement signal between the first hot-wire temperature sensor and the data processing device and / or between the second hot-wire temperature sensor and the data processing device.

[0020] The electronic control unit according to the invention is further advantageously developed in that the first heating wire temperature sensor and the second heating wire temperature sensor are each arranged in corner regions of the printed circuit board. Preferably, the corner regions in which the heating wire temperature sensors are arranged are thermally decoupled from the other regions of the printed circuit board by means of a recess in the printed circuit board. Thus, heat transfer from the one or more heat sources on the printed circuit board to the corner regions of the printed circuit board is essentially avoided.

[0021] In another preferred embodiment of the electronic control unit according to the invention, the data processing unit is configured to compare the first heating wire temperature and the second heating wire temperature to detect a malfunction, in particular a defect, of the first heating wire temperature sensor, the second heating wire temperature sensor, and / or the printed circuit board temperature sensor. If the difference between the first heating wire temperature and the second heating wire temperature exceeds a differential temperature limit, a malfunction, in particular a defect, of the first heating wire temperature sensor, the second heating wire temperature sensor, and / or the printed circuit board temperature sensor can be assumed. The differential temperature limit can be a static or a dynamic value.The differential temperature limit can, for example, depend on the temperature value detected by the circuit board temperature sensor. Alternatively, the differential temperature limit can be a parameterized value independent of the heating system and / or the vehicle seat, which is determined, for example, by a microcontroller in the electronic control unit during operation. This allows the electronic control unit to be used in different heating systems and / or vehicle seats without the need for a time-consuming and costly prior determination of a specific differential temperature limit for each individual heating system and / or vehicle seat. The electronic control unit is therefore extremely versatile and can be used in combination with various heating systems and / or vehicle seat designs.A malfunction or defect can result from an open circuit or a short circuit. Furthermore, a damaged heating wire mounting can cause a malfunction. Prolonged exposure to external temperatures can also lead to a malfunction. Additionally, damage to the heating wire itself can cause corresponding malfunctions.

[0022] In another embodiment of the electronic control unit according to the invention, the data processing unit is configured to compare the temporal changes of the first heating wire temperature and the temporal changes of the second heating wire temperature in order to detect a malfunction, in particular a defect, of the first heating wire temperature sensor, the second heating wire temperature sensor, and / or the printed circuit board temperature sensor. Furthermore, the data processing unit can be configured to perform maximum value monitoring of the first heating wire temperature and / or the second heating wire temperature in order to detect a malfunction, in particular a defect, of the first heating wire temperature sensor, the second heating wire temperature sensor, and / or the printed circuit board temperature sensor.If the first heating wire temperature and / or the second heating wire temperature exceed a maximum temperature occurring during the proper operation of the control unit, a malfunction, in particular a defect, of the first heating wire temperature sensor and / or the second heating wire temperature sensor can be assumed.

[0023] In a further preferred embodiment of the electronic control unit according to the invention, it is configured to control or regulate the heating of the heating wire as a function of a determined fictitious heating wire temperature and to determine the fictitious heating wire temperature taking into account the first heating wire temperature and the second heating wire temperature. In a safe operating mode of the heating device, the fictitious heating wire temperature can correspond to the higher of the first and second heating wire temperatures. In this way, it is prevented that areas of a vehicle seat are overheated by temperature control or regulation due to an incorrectly determined, too low heating wire temperature.If the higher of the redundantly determined heating wire temperatures is always provided in a corresponding temperature control system, unintentional intensification of the seat heating is avoided. In another operating mode, the fictitious heating wire temperature can be determined by averaging or weighting the first and second heating wire temperatures. Preferably, control of the heating wire's temperature can be implemented simultaneously with functional monitoring, so that a malfunction or defect of a temperature sensor can be detected even during the control or regulation of the heating wire's temperature.

[0024] In a further preferred embodiment of the electronic control unit according to the invention, it is configured to detect a change in distance to one or more heating wires, which are thermally coupled to a heating wire temperature sensor of the electronic control unit. If the electronic control unit comprises two heating wire temperature sensors, each thermally coupled to a heating wire segment, the electronic control unit can be configured to detect a symmetrical and / or an asymmetrical change in distance to the heating wire segments. In the case of a symmetrical change in distance, the thermal coupling of both heating wire temperature sensors to their respective heating wire segments is impaired or interrupted to the same extent.In the case of an asymmetrical change in distance, the thermal coupling of the heating wire temperature sensors to the respective heating wire segment is impaired to varying degrees, or the thermal coupling of only one heating wire temperature sensor to the respective heating wire segment is interrupted. By detecting such changes in distance, positional changes of the heating wire(s) or the electronic control unit can be identified. These changes in distance can be taken into account when evaluating the temperature sensor signals. If the measured values ​​of the heating wire temperature sensors change in a similar manner, this may indicate a decrease in the heating wire temperature or a symmetrical change in distance. In this case, a malfunction of the heating wire temperature sensors can be identified via the circuit board temperature sensor.If the measured values ​​of the heating wire temperature sensors change to varying degrees, this may indicate a malfunction of one of the heating wire temperature sensors or an asymmetrical change in distance. The problem underlying the invention is further solved by a heating device of the type mentioned above, wherein the electronic control unit of the heating device according to the invention is designed according to one of the embodiments described above.

[0025] Regarding the advantages and modifications of the heating device according to the invention, reference is first made to the advantages and modifications of the electronic control unit according to the invention.

[0026] The electronic control unit's at least one heating wire temperature sensor is preferably thermally coupled to the at least one heating wire. For example, the heating wire temperature sensor and the at least one heating wire are in contact with each other, thus implementing thermal coupling. Alternatively, the heating wire is positioned in close proximity to the at least one heating wire temperature sensor.

[0027] The problem underlying the invention is further solved by a heated vehicle seat of the type mentioned above, wherein the heating device of the heated vehicle seat according to the invention is designed according to one of the embodiments described above. With regard to the advantages and modifications of the heated vehicle seat according to the invention, reference is first made to the advantages and modifications of the heating device and the electronic control unit according to the invention.

[0028] In a preferred embodiment of the vehicle seat according to the invention, the data processing unit of the electronic control unit is configured to determine the current temperature of the backrest surface heated by the heating device and / or the current temperature of the seat cushion surface heated by the heating device, based on the temperature measurements of the circuit board temperature sensor and / or the at least one heating wire temperature sensor. For this purpose, the data processing unit uses at least one calculation algorithm based on past temperature measurements and current temperature measurements of the circuit board temperature sensor and / or the at least one heating wire temperature sensor, wherein the calculation algorithm preferably implements model predictive control or PID control.The calculation algorithm preferably takes into account a temperature profile determined by the circuit board temperature sensor and / or the at least one heating wire temperature sensor, for example, the temperature rise and / or fall over time. The temperatures measured by the circuit board temperature sensor and / or the at least one heating wire temperature sensor change proportionally to the actual heating wire temperature and the actual temperature of the heated backrest or seat surface. This proportionality can be used by the data processing unit to determine the current temperature of the heated backrest or seat surface. By integrating historical temperature measurements, the data processing unit can eliminate or at least significantly reduce the temperature influences of the control unit's heat sources.

[0029] The output power can therefore be written as follows: POUT=KP*P+KI*I+KD*D

[0030] Where P OUT The output power is K. P is a proportionality constant, K I is an integration constant and K D is a slope constant. The constants K P , K I and K D can be determined by testing or simulation. P is the temperature difference between the known temperature measurement and the temperature value to be calculated, for example, the temperature difference between the value measured by a heating wire temperature sensor and the temperature to be calculated for the heated backrest or seat surface. I is the integral of the aforementioned P-value over time, i.e., I=t0∫tP(t')dt' t0 is the start time of the heating season or another fixed time. t is the end time of the heating season or another fixed time. t' is the time-dimensioned integration variable. In this case, t0 is, for example, the time at which P OUT I is zero when P OUT The maximum output power is reached. D is the slope or steepness of the temperature change, i.e., the temperature increase or decrease.

[0031] By using appropriate control algorithms, the temperature measurement principle can be easily adapted to different heating systems or seat designs. Only the seat-specific constants K are required for this. P , K I and K Dto determine and store in the control unit. The constants can be determined through thermal tests or simulations. This eliminates the need for the complex development and implementation of seat-specific temperature determination.

[0032] The problem underlying the invention is further solved by a method of the type mentioned at the outset, wherein, within the framework of the method according to the invention, the temperature of the heating wire is determined by a data processing unit of the electronic control unit based on the temperature measurements of the printed circuit board temperature sensor and the at least one heating wire temperature sensor. Preferably, a heating device according to one of the embodiments described above is operated by means of the method according to the invention. Preferably, the method includes controlling and / or regulating the heating of the heating wire as a function of the determined temperature of the heating wire.

[0033] In a preferred embodiment of the method according to the invention, the acquisition of at least one temperature measurement value by means of at least one heating-wire temperature sensor of the electronic control unit is carried out by acquiring a first temperature measurement value and acquiring a second temperature measurement value. The first temperature measurement value is acquired by means of a first heating-wire temperature sensor of the electronic control unit, which is thermally coupled to the heating wire of the heating device. The second temperature measurement value is acquired by means of a second heating-wire temperature sensor of the electronic control unit, which is thermally coupled to the heating wire of the heating device.Determining the heating wire temperature based on the temperature readings from the circuit board temperature sensor and at least one heating wire temperature sensor is accomplished by determining a first heating wire temperature and a second heating wire temperature. The first heating wire temperature is determined based on the temperature readings from the first heating wire temperature sensor and the circuit board temperature sensor. The second heating wire temperature is determined based on the temperature readings from the second heating wire temperature sensor and the circuit board temperature sensor. This provides redundant temperature measurements at the heating wire, yielding two heating wire temperatures. The determined heating wire temperatures can be used for controlling or regulating the seat heating system.

[0034] In a further preferred embodiment of the method according to the invention, the first heating wire temperature and the second heating wire temperature are compared with each other in order to detect a functional impairment, in particular a defect, of the first heating wire temperature sensor, the second heating wire temperature sensor, and / or the printed circuit board temperature sensor. Alternatively or additionally, the change over time of the first heating wire temperature and the change over time of the second heating wire temperature are compared with each other in order to detect a functional impairment, in particular a defect, of the first heating wire temperature sensor, the second heating wire temperature sensor, and / or the printed circuit board temperature sensor based on this comparison. Furthermore, the method can include determining a fictitious heating wire temperature taking into account the first heating wire temperature and the second heating wire temperature.Alternatively or additionally, the process involves controlling and / or regulating the heating of the heating wire depending on the determined fictitious heating wire temperature.

[0035] Preferred embodiments of the invention are explained and described in more detail below with reference to the accompanying drawings. These show: Fig. 1 an embodiment of the electronic control unit according to the invention in a top view; Fig. 2 that in the Fig. 1 Electronic control unit shown in a rear view; Fig. 3. Determining heating wire temperatures in a schematic block diagram; Fig. 4 a heating device according to the invention in a schematic representation; Fig. 5 a schematic diagram of the circuitry of a control unit according to the invention; Fig. 6 possible line defects in the Fig. 5 shown circuit diagrams in a schematic representation; and Fig. 7 other possible line defects in the Fig. 5 shown circuit diagrams in a schematic representation.

[0036] The Fig. 1 and the Fig. Figure 2 shows the front and back of a circuit board 12 of an electronic control unit 10 for a heating device 100 of a vehicle seat.

[0037] Several heat sources 14a-14c are arranged on the circuit board 12. The heat sources 14a-14c are integrated circuits, with heat source 14a being a microcontroller. Heat source 14b is a low-side driver (LS circuit) and heat source 14c is a high-side driver (HS circuit).

[0038] Three temperature sensors 16, 18a, 18b, designed as NTC resistors, are arranged on the circuit board 12. The circuit board temperature sensor 16 is part of the microcontroller 14 and is therefore thermally coupled to the microcontroller 14a. Due to the arrangement of the microcontroller 14a on the circuit board 12, the circuit board temperature sensor 16 is also thermally coupled to the heat source 14c.

[0039] The heating wire temperature sensors 18a, 18b are arranged in corner regions 26a, 26b of the circuit board 12 and are configured to be thermally coupled to a heating wire 102 of the heating device 100. For this purpose, the heating wire temperature sensors 18a, 18b can be in contact with wire sections 104a, 104b of the heating wire 102. Alternatively, the heating wire temperature sensors 18a, 18b can also be arranged in the immediate vicinity of wire sections 104a, 104b of the heating wire.

[0040] Furthermore, the circuit board 12 has connection areas 20 for additional electronic components, in particular measuring devices. For example, an additional external temperature sensor can be connected to the circuit board electronics via connection area 20. The additional external temperature sensor can be positioned at a distance from the circuit board 12 and provide additional temperature readings.

[0041] The electronic control unit 10 has a data processing unit 22, wherein, in the illustrated embodiment, the heat source 14a, designed as a microcontroller, constitutes the data processing unit 22. Using the data processing unit 22, the temperature of the heating wire 102 can be redundantly determined based on the temperature measurements TS1, TS2, TS3 of the circuit board temperature sensor 16 and the heating wire temperature sensors 18a, 18b.

[0042] The heating wire temperature sensors 18a, 18b only determine the temperature of the heating wire 102 approximately, since the temperature readings TS1, TS2 of the heating wire temperature sensors 18a, 18b are distorted by external thermal influences due to the integration of the heating wire temperature sensors 18a, 18b into the control unit 10. However, by taking into account the temperature reading TS3 of the circuit board temperature sensor 16, the distortion of the measured value caused by the thermal influences can be compensated for.

[0043] To essentially prevent the thermal influences of the heat sources 14a-14c on the hot-wire temperature sensors 18a, 18b, the hot-wire temperature sensors 18a, 18b are thermally insulated from the multiple heat sources 14a-14c arranged on the circuit board 12. The thermal insulation of the hot-wire temperature sensors 18a, 18b is achieved via L-shaped recesses 24a, 24b in the circuit board 12. Recess 24a acts as a heat flow barrier for hot-wire temperature sensor 18a. Recess 24b acts as a heat flow barrier for hot-wire temperature sensor 18b.

[0044] The Fig. Figure 3 shows the redundant determination of the heating wire temperature TW1, TW2, which is carried out according to the following principle: Due to the thermal coupling of the heating wire temperature sensor 18a with a wire section 104a of the heating wire 102, heat QW1 is transferred from the wire section 104a towards the heating wire temperature sensor 18a. Additionally, heat Q3 is transferred from the area where the circuit board temperature sensor 16 is located to the heating wire temperature sensor 18a. The area where the circuit board temperature sensor 16 is located is also heated by heat QP1 emanating from heat source 14a and heat QP3 emanating from heat source 14c. Heat source 14a is heated by the input of energy P1. Heat source 14c is heated by the input of energy P3. Assuming that the temperature measurement TS1 of the heating wire temperature sensor 18a remains constant, the following relationship results: Q3−QW1=0. Since the heat transfer results from the product of the temperature difference between the heat exchange objects and various constants, the following relationship can be derived: TW1=Total constant1×TS1−Total constant2×TS3. Thus, the heating wire temperature TW1 can be determined based on the temperature measurements TS1, TS3 of the first heating wire temperature sensor 18a and the circuit board temperature sensor 16, provided that the total constants have been determined beforehand.

[0045] Due to the thermal coupling of the heating wire temperature sensor 18b with a wire section 104b of the heating wire 102, heat QW2 is transferred from the wire section 104b towards the heating wire temperature sensor 18b. Additionally, heat Q3' is transferred from the area where the circuit board temperature sensor 16 is located to the heating wire temperature sensor 18b. The area where the circuit board temperature sensor 16 is located is also heated by the heat QP2 emanating from the heat source 14b. The heat source 14b is heated by the supply of energy P2. Assuming that the temperature reading TS2 of the heating wire temperature sensor 18a remains constant, the following relationship results: Q3'−QW2=0.

[0046] Since the heat transfer results from the product of the temperature difference between the heat exchange objects and various constants, the following relationship can be derived: TW2=total constant3×TS2−total constant4×TS3.

[0047] Thus, the heating wire temperature TW2 can be determined based on the temperature measurements TS2, TS3 of the second heating wire temperature sensor 18b and the circuit board temperature sensor 16, provided that the total constants have been determined beforehand.

[0048] The redundant temperature measurement thus allows the determination of two heating wire temperatures TW1 and TW2. These heating wire temperatures TW1 and TW2 can be used to detect a malfunction, in particular a defect, of the first heating wire temperature sensor 18a, the second heating wire temperature sensor 18b, or the printed circuit board temperature sensor 16. For this purpose, the first heating wire temperature TW1 and the second heating wire temperature TW2 are compared. If the difference between the first heating wire temperature TW1 and the second heating wire temperature TW2 exceeds a differential temperature limit, a malfunction, in particular a defect, of a heating wire temperature sensor 18a, 18b, or the printed circuit board temperature sensor 16 can be assumed. The differential temperature limit can be a static or a dynamic value.If the differential temperature limit is a dynamic value, it may, for example, depend on the temperature value TS3 detected by the circuit board temperature sensor 16.

[0049] Alternatively or additionally, to detect a malfunction in the temperature sensing, the change over time of the first heating wire temperature TW1 and the change over time of the second heating wire temperature TW2 can be compared. Furthermore, maximum value monitoring of the first heating wire temperature TW1 and / or the second heating wire temperature TW2 can be performed to detect a malfunction. If the first heating wire temperature TW1 or the second heating wire temperature TW2 exceeds a maximum temperature occurring during the proper operation of the control unit 10, a malfunction of a heating wire temperature sensor 18a, 18b or the circuit board temperature sensor 16 can be assumed.

[0050] The electronic control unit 10 is preferably used to control or regulate the heating of the heating wire 102 as a function of a determined fictitious heating wire temperature TWF. The fictitious heating wire temperature TWF can be determined taking into account the first heating wire temperature TW1 and the second heating wire temperature TW2. For example, the fictitious heating wire temperature TWF can be determined by averaging or weighting the first heating wire temperature TW1 and the second heating wire temperature TW2.

[0051] The Fig. Figure 4 shows a heating device 100 with a heatable heating wire 102 and an electronic control unit 10. The electronic control unit 10 serves to control the heating of the heating wire 102 and to monitor the temperature of the heating wire 102.

[0052] The heating device 100 shown can, for example, be used in a heated vehicle seat, which comprises a seat cushion and a backrest. The seat cushion provides a seating surface for the user's buttocks. The backrest provides a support surface for the user's back. The heating wire 102 can be integrated into the seat cushion and / or the backrest and heats the seating surface and / or the backrest surface during operation of the heating device 100.

[0053] The Fig. Figure 4 further shows that the wire sections 104a, 104b of the heating wire 102, to which the heating wire temperature sensors 18a, 18b are thermally coupled, represent spaced-apart segments of the heating wire 102. In the illustrated embodiment, the heating wire 102 is fixed to the electronic control unit 10 in only two areas. In principle, the heating wire 102 can also be fixed to the control unit 10 in more than two areas. Different heating wires 102 can also be coupled to the electronic control unit 10.

[0054] The Fig. Figure 5 shows a circuit 28 of a control unit 10 with a first heated-wire temperature sensor 18a, a second heated-wire temperature sensor 18b, a data processing unit 22, and a voltage source 30. The electrical power supply to the first heated-wire temperature sensor 18a, the second heated-wire temperature sensor 18b, and the data processing unit 22 is provided via lines 36a and 36b. The measurement signal transmission between the first heated-wire temperature sensor 18a and the data processing unit 22 is provided via line 38a. The measurement signal transmission between the second heated-wire temperature sensor 18b and the data processing unit 22 is provided via line 38b.

[0055] The Fig. Figure 6 shows possible line defects 32a-32f in the circuit 28, where only one of the two heating wire temperature sensors 18a, 18b fails. With line defects 32a, 32e, 32f, only heating wire temperature sensor 18a fails. With line defects 32b, 32c, 32d, only heating wire temperature sensor 18b fails.

[0056] The Fig. Figure 7 shows possible line defects 34a-34f in the circuit 28, in which both heating wire temperature sensors 18a and 18b fail. However, in the case of these line defects 34a-34f, the data processing unit 22 can detect the failure of both heating wire temperature sensors 18a and 18b, so that, for example, the operation of the heating device 100 can be adjusted or interrupted accordingly. An undetected failure of both heating wire temperature sensors 18a and 18b can be effectively prevented via the circuit 28. Reference sign 10 Control unit 12 circuit boards 14a-14c Heat sources 16 PCB temperature sensors 18a, 18b Heating wire temperature sensors 20 connection areas 22 Data processing facility 24a, 24b Exemption 26a, 26b Corner areas 28 Wiring 30 Voltage source 32a-32f Line defects 34a-34f Line defects 36a, 36b lines 38a, 38b lines 100 Heating equipment 102 heating wire 104a, 104b wire sections P1, P2, P3 Energies TS1, TS2 Temperature readings from the heating wire temperature sensors TS3 temperature readings from the circuit board temperature sensor TW1, TW2 heating wire temperatures TWF fictitious heating wire temperature QW1, QW2 Heat Q3, Q3' Heat QP1, QP2, QP3 Heat

Claims

[1] Electronic control unit (10) for a heating device (100) of a vehicle seat, with - a printed circuit board (12) on which one or more heat sources (14a-14c) are arranged; - a printed circuit board temperature sensor (16) which is thermally coupled to at least one heat source (14a-14c) on the printed circuit board (12); and - at least one heating wire temperature sensor (18a, 18b) which is designed to be thermally coupled to a heating wire (102) of the heating device (100); characterized by a data processing device (22) which is configured to determine the temperature of the heating wire (102) on the basis of the temperature measurements (TS1, TS2, TS3) of the printed circuit board temperature sensor (16) and of the at least one heating wire temperature sensor (18a, 18b). [2] Electronic control unit (10) according to claim 1, characterized by, that the printed circuit board temperature sensor (16) and / or the at least one heating wire temperature sensor (18a, 18b) are each designed as a thermistor, arranged on the printed circuit board (12) and / or integrated or embedded in the printed circuit board (12) or an electronic component arranged on the printed circuit board (12). [3] Electronic control unit (10) according to claim 1 or 2, characterized by , that the at least one heating wire temperature sensor (18a, 18b) is thermally insulated from the one or more heat sources (14a-14c) arranged on the circuit board (12) and / or the circuit board temperature sensor (16). [4] Electronic control unit (10) according to any one of the preceding claims, characterized by, that the printed circuit board (12) has at least one recess (24a, 24b) which is positioned between the at least one heating wire temperature sensor (18a, 18b) and at least one heat source arranged on the printed circuit board (12) and / or the printed circuit board temperature sensor (16). [5] Electronic control unit (10) according to any one of the preceding claims, characterized by a first heating wire temperature sensor (18a) and a second heating wire temperature sensor (18b), each of which is configured to be thermally coupled to the heating wire (102) of the heating device (100), wherein the data processing device (22) is configured to determine a first heating wire temperature (TW1) based on the temperature measurements (TS1) of the first heating wire temperature sensor (18a) and a second heating wire temperature (TW2) based on the temperature measurements (TS2) of the second heating wire temperature sensor (18b). [6] Electronic control unit (10) according to claim 5, characterized by , that the data processing device (22) is configured to determine a first heating wire temperature (TW1) based on the temperature measurements (TS1, TS3) of the first heating wire temperature sensor (18a) and the circuit board temperature sensor (16) and a second heating wire temperature (TW2) based on the temperature measurements (TS2, TS3) of the second heating wire temperature sensor (18b) and the circuit board temperature sensor (16). [7] Electronic control unit (10) according to claim 5 or 6, characterized by a circuit (28) in which the first heating wire temperature sensor (18a), the second heating wire temperature sensor (18b) and the data processing device (22) are connected to each other and to a voltage source (30) in such a way that in the event of a line defect in the circuit (28) the data processing device (22) can detect the failure of both heating wire temperature sensors (18a, 18b). [8] Electronic control unit (10) according to one of claims 5 to 7, characterized by , that the first heating wire temperature sensor (18a) and the second heating wire temperature sensor (18b) are each arranged in corner areas (26a, 26b) of the circuit board (12). [9] Electronic control unit (10) according to any one of claims 5 to 8, characterized by , that the data processing device (22) is configured to compare the first heating wire temperature (TW1) and the second heating wire temperature (TW2) to detect a malfunction, in particular a defect, of the first heating wire temperature sensor (18a), the second heating wire temperature sensor (18b) and / or the printed circuit board temperature sensor (16). [10] Electronic control unit (10) according to any one of claims 5 to 9, characterized by, that the data processing device (22) is configured to compare the temporal change of the first heating wire temperature (TW1) and the temporal change of the second heating wire temperature (TW2) to detect a malfunction, in particular a defect, of the first heating wire temperature sensor (18a), the second heating wire temperature sensor (18b) and / or the printed circuit board temperature sensor (16). [11] Electronic control unit (10) according to any one of claims 5 to 10, characterized by , that the control unit (10) is configured to control or regulate the heating of the heating wire (102) depending on a determined fictitious heating wire temperature (TWF) and to determine the fictitious heating wire temperature (TWF) taking into account the first heating wire temperature (TW1) and the second heating wire temperature (TW2). [12] Heating device (100) for a vehicle seat, with - at least one heatable heating wire (102); and - an electronic control unit (10) which is designed to control the heating of the heating wire (102) and to monitor the temperature of the heating wire (102); characterized by , that the electronic control unit (10) is designed according to one of the preceding claims. [13] Heated vehicle seat, with - a seat cushion which provides a seating surface for the buttocks of a user; - a backrest that provides a support surface for the user's back; and - a heating device (100) which has one or more heating wires (102) integrated into the seat cushion and / or the backrest and is designed to heat the seat surface and / or the backrest surface via the one or more heating wires (102); characterized by , that the heating device (100) is designed according to claim 12. [14] Heated vehicle seat according to claim 13, characterized by , that the data processing unit (22) of the electronic control unit (10) is configured to determine the current temperature of the backrest surface heated by the heating unit (100) and / or the current temperature of the seat surface of the seat cushion heated by the heating unit (100) on the basis of the temperature measurements (TS1, TS2, TS3) of the circuit board temperature sensor (16) and / or of the at least one heating wire temperature sensor (18a, 18b). [15] Method for operating a heating device (100) of a vehicle seat, in particular a heating device (100) according to claim 12, comprising the steps: - Detecting a temperature value by means of a printed circuit board temperature sensor (16) of an electronic control unit (10) of the heating device (100), wherein the printed circuit board temperature sensor (16) is thermally coupled to at least one heat source (14a-14c) on a printed circuit board (12) of the electronic control unit (10); and - Recording at least one temperature measurement value by means of at least one heating wire temperature sensor (18a, 18b) of the electronic control unit (10), which is thermally coupled to a heating wire (102) of the heating device (100); characterized by the step: - Determining the temperature of the heating wire (102) based on the temperature measurements (TS1, TS2, TS3) of the printed circuit board temperature sensor (16) and of the at least one heating wire temperature sensor (18a, 18b) by a data processing unit (22) of the electronic control unit (10). [16] Method according to claim 15, characterized by, that the acquisition of at least one temperature measurement value by means of at least one heating wire temperature sensor (18a, 18b) of the electronic control unit (10) is carried out by the following steps: - Acquiring a first temperature measurement by means of a first heating wire temperature sensor (18a) of the electronic control unit (10), which is thermally coupled to the heating wire (102) of the heating device (100); and - Acquiring a second temperature measurement by means of a second heating wire temperature sensor (18b) of the electronic control unit (10), which is thermally coupled to the heating wire (102) of the heating device (100); wherein the determination of the temperature of the heating wire (102) based on the temperature measurements (TS1, TS2, TS3) of the printed circuit board temperature sensor (16) and of the at least one heating wire temperature sensor (18a, 18b) is carried out by the following steps: - Determining a first heating wire temperature (TW1) based on the temperature readings (TS1, TS3) of the first heating wire temperature sensor (18a) and the printed circuit board temperature sensor (16); and - Determining a second heating wire temperature (TW2) based on the temperature measurements (TS2, TS3) of the second heating wire temperature sensor (18b) and the circuit board temperature sensor (16). [17] Method according to claim 16, characterized by at least one of the following steps: - Comparing the first heating wire temperature (TW1) and the second heating wire temperature (TW2) to detect a malfunction, in particular a defect, of the first heating wire temperature sensor (18a), the second heating wire temperature sensor (18b) and / or the printed circuit board temperature sensor (16); - Comparing the time-dependent changes of the first heating wire temperature (TW1) and the time-dependent changes of the second heating wire temperature (TW2) to detect a malfunction, in particular a defect, of the first heating wire temperature sensor (18a), the second heating wire temperature sensor (18b) and / or the printed circuit board temperature sensor (16); - Determining a fictitious heating wire temperature (TWF) taking into account the first heating wire temperature (TW1) and the second heating wire temperature (TW2); - Controlling and / or regulating the heating of the heating wire (102) depending on a determined fictitious heating wire temperature (TWF).

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