DE102020208561A1 - Method for operating a heater for heating a device of a motor vehicle and heating device for heating a device for a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a heater for heating a device in a motor vehicle, the device having a cover which at least partially covers the heater, with the steps of specifying a temperature Treference,setpoint of the reference (13); and determining a temperature using at least one temperature sensor (15) which is arranged in or on the device. According to the invention, the heating (14) is regulated, with a setpoint temperature TSensor,Sollam temperature sensor (15) being used as the setpoint for the regulation, which is determined with the aid of a correction variable Δ from the specified temperature Treference,Solldes reference (13), where the correction variable Δ depends on the specified temperature Tref,setpoint of the reference (13) and a temperature T∞ of an area surrounding the reference (13) outside the device. The invention also relates to a heating device for heating a device in a motor vehicle.

Description

The invention relates to a method for operating a heater for heating a device of a motor vehicle according to the preamble of claim 1 and a heating device for heating a device of a motor vehicle according to the preamble of claim 9.

For example, steering wheel heaters for heating a steering wheel of a motor vehicle are known from the prior art. For example, describes the DE 10 2017 102 688 A1 a steering wheel heater, the heating wires of which extend along an actuation area of the steering wheel in the form of a steering wheel rim. The heating is regulated using a temperature sensor arranged in foam around the steering wheel rim. A difficulty with such a regulation is that the temperature at the temperature sensor deviates from the temperature of interest on an outside of an outer cover of the steering wheel, for example a leather cover.

The problem on which the invention is based is to generate a temperature that is as constant as possible in or on a cover of a device of the vehicle.

This problem is solved by providing the method with the features of claim 1 and the heating device with the features of claim 9. Further developments of the invention are specified in the dependent claims.

• - Vorgeben einer Temperatur T_{Bezug, Soll} des Bezugs; und
• - Ermitteln einer Temperatur mit Hilfe mindestens eines Temperatursensors, der in oder an der Vorrichtung angeordnet ist; und
• - Regeln der Heizung, wobei als Sollwert der Regelung eine Soll-Temperatur T_{Sensor, Soll} am Temperatursensor verwendet wird, die mit Hilfe einer Korrekturgröße Δ aus der vorgegebenen Temperatur T_{Bezug, Soll} des Bezugs bestimmt wird, wobei die Korrekturgröße Δ von der vorgegebenen Temperatur T_{Bezug, Soll} des Bezugs und einer Temperatur T_∞ einer Umgebung des Bezugs außerhalb der Vorrichtung abhängt.

Accordingly, a method for operating a heater for heating a device of a motor vehicle is provided, the device having a cover that at least partially covers the heater, with the steps:

• - specifying a temperature T _{reference, target} reference; and
• - Determining a temperature using at least one temperature sensor which is arranged in or on the device; and
• - Regulating the heating, with a setpoint temperature T _{sensor, setpoint} at the temperature sensor being used as the setpoint for the regulation, which is determined using a correction variable Δ from the specified temperature T _{reference, setpoint of} the reference, the correction variable Δ depending on the specified temperature T _{reference, target} reference and a temperature T _∞ an environment of the reference outside of the device depends.

With the help of the correction variable Δ it is taken into account that the temperature measured with the temperature sensor does not match the relevant temperature of the reference. In particular, the temperature sensor is located in an area of the vehicle that is spaced apart from the cover. In particular, the heater has at least one heating conductor and/or at least one heating mat.

It is conceivable that the heater is a heater for a steering device of the vehicle, with the heating conductor or the heating mat being accommodated, for example, in an actuation area of the steering device. For example, the steering device is designed in the manner of a steering wheel, with a steering wheel rim running around a hub forming the actuation area, via which a driver of the vehicle can specify a steering angle. The invention is not limited to a specific configuration of the steering device. It is conceivable, for example, that the steering device is not designed as a classic steering wheel, but merely has actuating handles or is designed in the manner of a joystick. The heater can also be a seat heater, the heating conductors or the heating mat of which are arranged underneath a seat cover, in particular a seat surface, of a vehicle seat.

According to the method according to the invention, both the specified temperature T _{reference, target value of} the reference and the ambient temperature T _∞ flow into the determination of the correction quantity Δ. In this way, the temperature at the temperature sensor can be corrected as precisely as possible with regard to the specified temperature of the cover, as a result of which the temperature of the cover can be kept within specified tolerances in particular. The specified temperature T _{reference, setpoint of} the reference is, for example, a temperature on an outside of the reference. In the case of a steering device, this is that side of the cover which a driver comes into contact with when the actuating area of the steering device is actuated. The ambient temperature relates in particular to a temperature of a medium adjacent to the outside of the cover, in particular air. For example, the temperature of this medium is determined within a definable distance (eg 10 cm, 20 cm, 50 cm or 100 cm) from the outside of the cover.

The setpoint temperature T _{sensor, setpoint} at the temperature sensor is determined, for example, according to the equation T _{sensor, setpoint} =T _{reference, setpoint} +Δ.

The correction quantity Δ in turn can be determined according to Δ=(T _{reference, target} −T _∞ )*P, where P is a constant to be determined by a calibration measurement. The derivation of this relationship is based in particular on the assumption that the main mechanism of heat transport from the temperature sensor to the reference is heat conduction and the dissipation of heat from the reference to the environment is primarily by convection.

For example, the following relationship can be assumed for the heat flow Q̇1 based on heat conduction from the temperature sensor to the reference (e.g. to an outside of the reference): $$\dot{Q}1=k\cdot A_W\cdot \frac{T_{SensO\mathrm{right}}-T_{Be\mathrm{e.g}\mathrm{and}G}}{\mathrm{i.e}}$$

Here, k denotes the (particularly averaged) thermal conductivity of the material between the temperature sensor and the leather surface, Aw the area through which the heat flow flows, d the distance between the temperature sensor and the cover (particularly between the temperature sensor and the outside of the cover), T _sensor die Temperature at the temperature sensor and T _reference the temperature of the reference, in particular the outside of the reference.

The convective heat flow from the reference to the environment can be described as follows: $$\dot{Q}2=H\cdot A_0\cdot \left(T_{Be\mathrm{e.g}\mathrm{and}G}-T_{\infty }\right)$$

where h is the heat transfer coefficient and A _{0 is} the outer surface of the cover.

Dabei ist $\frac{h\cdot A_0\cdot d}{k\cdot A_W}$

die Konstante P. Die Konstante P hängt somit von der Geometrie und den verwendeten Materialien der Vorrichtung ab, wobei P beispielsweise für gleiche Vorrichtungen (insbesondere Lenkräder oder Fahrzeugsitze) einer Serienproduktion zumindest näherungsweise identisch sein kann. Denkbar ist daher, dass die Konstante P mit einer Testmessung (insbesondere einmalig) bestimmt und dann für sämtliche Exemplare der Serie verwendet wird. Möglichst ist natürlich auch, dass die Konstante P individuell für jede Vorrichtung ermittelt wird.Assuming that the heat flows Q̇1 and Q2 are equal, we get: $$T_{SensO\mathrm{right}}-T_{Be\mathrm{e.g}\mathrm{and}G}=\frac{H\cdot {\mathrm{<figure-callout\; id="0"\; label="A"\; filenames="DE102020208561A1\_0006.png"\; state="\{\{state\}\}">A</figure-callout>}}_0\cdot \mathrm{i.e}}{k\cdot A_W}(\left(T_{Be\mathrm{e.g}\mathrm{and}G}-T_{\infty }\right)$$

there is $\frac{H\cdot A_0\cdot \mathrm{i.e}}{k\cdot A_W}$

the constant P. The constant P thus depends on the geometry and the materials used in the device, where P can be at least approximately identical for example for the same devices (in particular steering wheels or vehicle seats) of a series production. It is therefore conceivable that the constant P is determined with a test measurement (in particular once) and then used for all copies of the series. Of course, it is also possible for the constant P to be determined individually for each device.

According to a further initial example of the invention, the heating is regulated with the aid of continuous regulation (and not, for example, with two-point regulation). For example, the continuous regulation includes a P regulation or a PI regulation. With the help of a continuous control, for example, compared to an unsteady control, the temperature at the temperature sensor and thus the temperature of the reference can be produced with less oscillation. The use of such a continuous control can also contribute to maintaining a specified tolerance range for the temperature of the reference. In particular, a smaller part of the specified tolerance range is "used up" by the swinging of the temperature, so that there is greater scope for disturbance variables that affect the difference between the temperature at the temperature sensor and the temperature of the reference. The "disturbance variables" are, for example, manufacturing and/or assembly tolerances in relation to components of the device; for example steering wheel components, in particular with regard to structures of a steering wheel rim or another area of a steering device in which the heating and the temperature sensor are accommodated.

It is also conceivable that the heating is controlled with the aid of a cascaded controller, which has at least one master controller with the setpoint temperature T _{sensor, setpoint} at the temperature sensor as the setpoint and a slave controller which has a _setpoint dependent on the setpoint _{temperature T sensor, setpoint} -Heating power P _{set used} as set point includes. For example, the slave controller generates a PWM signal as an output variable. Of course, it is also conceivable that only one-stage control is used, which also outputs a PWM signal, for example. With the use of a cascaded regulation, however, a fluctuation in a voltage of the vehicle electrical system can be compensated for, for example. With cascaded control, the master controller first determines the required power, which is set by the slave controller by adapting the PWM signal. For example, the PWM signal generated by the slave controller is doubled when the available on-board voltage is halved. _{The power required to reach or maintain the setpoint temperature T sensor, setpoint} at the temperature sensor can thus be set, in particular even if the on-board voltage fluctuates.

• - einer unterhalb eines Bezugs der Vorrichtung anordenbaren Heizung zum Beheizen der Vorrichtung;
• - einer Einheit zum Erfassen einer vorgegebenen Temperatur T_{Bezug, Soll} des Bezugs und einer mit mindestens einem in oder an der Vorrichtung angeordneten Temperatursensor gemessenen Temperatur; und
• - einer Regelung zum Regeln der Heizung, wobei die Regelung ausgebildet ist, als Sollwert eine Temperatur T_{Sensor, Soll} am Temperatursensor zu verwenden, die mit Hilfe einer Korrekturgröße Δ aus der vorgegebenen Temperatur T_{Bezug, Soll} des Bezugs bestimmt ist, wobei die Korrekturgröße von der vorgegebenen Temperatur T_{Bezug, Soll} des Bezugs und einer Temperatur T_∞ einer Umgebung des Bezugs außerhalb der Vorrichtung abhängt.

The invention also relates to a heating device for heating a device of a motor vehicle, in particular for carrying out the method according to the invention

• - A heater which can be arranged below a cover of the device for heating the device;
• - A unit for detecting a predetermined temperature T _{reference, setpoint of} the reference and a temperature measured with at least one temperature sensor arranged in or on the device; and
• - A control for controlling the heating, wherein the control is designed as a setpoint to use a temperature T _{sensor, target} on the temperature sensor, which is determined using a correction variable Δ from the specified temperature T _{reference, target of} the reference, the correction _{variable of the specified temperature T reference, target of} the reference and a temperature T _{∞ of} an environment of the cover depends outside the device.

The exemplary embodiments explained above in relation to the method according to the invention can, of course, also be used analogously to develop the heating device according to the invention. For example, the heating of the heating device has at least one heating conductor or at least one heating mat. The control is implemented in particular by a programmable device, for example in the form of a vehicle ECU.

It is conceivable that the temperature sensor is arranged in or on the heating element or the heating mat (for example adjacent to the heating element or the heating mat). The temperature sensor can be implemented by an NTC sensor or another resistance sensor. However, the invention is of course not limited to a specific type of sensor.

The invention also relates to a device for a motor vehicle with a heating device according to the invention. It is conceivable that the device is a steering device and the temperature sensor of the heating device is arranged in a foam casing around a skeleton of the steering device or between a foam casing around the skeleton and the cover. As already mentioned above, however, the heating device according to the invention can also be used, for example, to heat a device in the form of a vehicle seat.

The cover of the device is made, for example, at least partially from leather or a plastic.

• 1 einen Schnitt durch einen Lenkradkranz eines Lenkrads;
• 2 eine Illustration eines Modells des Wärmetransports in dem Lenkrad aus 1;
• 3 ein Schaltbild einer Regelung einer erfindungsgemäßen Heizvorrichtung;
• 4 Temperaturmessungen an einem Lenkrad bei Verwendung einer erfindungsgemäßen Heizvorrichtung und Änderung der Umgebungstemperatur; und
• 5 Vergleich von Temperaturmessungen an einem Lenkrad bei Verwendung einer erfindungsgemäßen und einer herkömmlichen Heizvorrichtung.

The invention is explained in more detail below using exemplary embodiments with reference to the figures. Show it:

• 1 a section through a steering wheel rim of a steering wheel;
• 2 an illustration of a model of heat transport in the steering wheel 1 ;
• 3 a circuit diagram of a control of a heating device according to the invention;
• 4 Temperature measurements on a steering wheel when using a heating device according to the invention and changing the ambient temperature; and
• 5 Comparison of temperature measurements on a steering wheel when using a heating device according to the invention and a conventional one.

the inside 1 The steering wheel rim 1 shown in a section of a steering device in the form of a steering wheel of a motor vehicle runs around a central area of the steering wheel and has a steering wheel skeleton 11 surrounded by foam 12 . The steering wheel rim 1 forms an actuating device of the steering wheel, with a driver of the motor vehicle being able to adjust a steering angle by actuating the steering wheel rim 1 in a known manner. Above the encapsulation 12 , the steering wheel rim 1 has a cover 13 (for example in the form of a leather cover), which forms an outer surface 131 of the steering wheel rim 1 . There is also a heating device for heating the steering wheel.

The heating device comprises a steering wheel heater 14 which is arranged between the encapsulation 12 and the cover 13 and has one or more heating conductors and/or a heating mat 141 . The heating conductors or the heating mat 141 could also be located at least partially in the foam casing 12 . To determine and regulate the temperature in the steering wheel rim 1 is in the area of the heater 14, d. H. in particular between the foam casing 12 and the cover 13, at least one temperature sensor 15 of the heating device, which is designed, for example, in the manner of an NTC sensor. Of course, the use of other sensor types is also conceivable. The temperature sensor 15 is accommodated, for example, at least partially between the heating conductors or within the heating mat 141 . It is also conceivable that the temperature sensor 15 is located partially or completely between the heating conductors or the heating mat 141 and the cover 13 or partially or completely between the heating conductors or the heating mat 141 and the foam casing 12 . Of course, it is also possible for the temperature sensor 15 to be arranged at least partially in the foam casing 12 .

In particular, the heater 14 is intended to generate a predetermined temperature on the outside 131 of the cover 13 . This is done using (particularly constant) control, with a target temperature T _{sensor, target} at temperature sensor 15 being used as the target value of the control, as already explained above, which is calculated using a correction variable Δ from the specified temperature T _{reference, target} of the reference 13 is determined. The correction variable Δ depends on the specified temperature T _{reference, setpoint of} the reference 13 and a temperature T _{∞ of} the area surrounding the reference 13 outside of the steering wheel rim 1 . The control is therefore not subject to a fixed temperature offset between the temperature at Temperartursensor and the temperature of the reference specified, but it is based on both the ambient temperature T _∞ and the desired temperature T _{reference, setpoint of} the reference 13 (in particular a desired temperature of the reference 13 on its outside 131) dependent temperature offset. As a result, deviations in the temperature of the reference 13 from the specified temperature T _{reference, set point} , in particular when the ambient temperature changes, can be kept as small as possible; see, for example, the measurement curves of 4 and 5 .

It is possible that the correction variable Δ is determined according to the relationship Δ=(T _{reference, target} −T _∞ )*P, where P is a constant to be determined by a calibration measurement, as already explained above. On the one hand, this relationship is based on the assumption that the heat flow from the temperature sensor 15 to the surface 131 of the cover 13 is essentially due to the thermal conductivity of the path between the temperature sensor 15 and the surface 131, i.e. in particular due to the thermal conductivity of materials in the area of the heater 14 and the material of the reference 13 and heat transfer between the heater 14 and the reference 13 depends. On the other hand, it is assumed that the heat is dissipated from the surface 131 of the cover 13 essentially by convection. Both processes are shown schematically in 2 shown (heat conduction WL, convection K). The thermal conduction between the temperature sensor 15 and the surface 131 of the cover 13 is also in 1 indicated by arrows WL. The convection from the surface 131 of the reference 13 to the environment is denoted by arrows K.

To control the heating, for example the heating 14 1 , can a in 3 shown cascaded controller 140 can be used. The rule 140 includes a first, outer control loop 141 and a second, inner control loop 142. The outer control loop 141 can be viewed as a master controller, which receives _{the desired temperature at the temperature sensor T sensor, setpoint as an input variable.} The inner control loop 142 can be viewed as a slave controller that _{uses a setpoint heating power P setpoint} dependent on the setpoint _{temperature T sensor, setpoint of} the temperature sensor as setpoint and generates a PWM signal as the output signal. The PWM signal is converted by the heating into an output heating power P _heating (according to a first transfer function G ₁ (s)). The heating power P _heating in turn determines the temperature T _sensor at the temperature sensor (according to a second transfer function G ₂ (s)). The cascaded regulation 140 enables in particular a regulation of the sensor temperature that is at least essentially independent of a supply voltage (for example an on-board voltage provided by a vehicle), as already explained above.

In the embodiment of 3 the outer control circuit 141 is designed as a PI controller and the inner control circuit 142 as a P controller. Correspondingly, the outer control loop 141 has a P element having an amplifier 1411 and an I element 1412 . In addition, there is feedback 1413 and a switch 1414, which are used to avoid undesirable windup effects (eg a delay in regulation) that could occur with large values of the manipulated variable. The inner control loop 142 includes a limiter 1421 for limiting the amplitude of the PWM signal and an amplifier 1422 . However, the invention is not limited to a specific type of regulation. The use of a non-cascaded controller or an unsteady controller would also be conceivable.

4 shows the result of a test measurement on a steering wheel with a heating device (steering wheel heating) according to the invention, the time being plotted on the x-axis and temperature values on the y-axis. For the test measurement, the steering wheel was first cooled down to minus 20 °C in a climatic chamber. When the steering wheel heating was switched on, the climate chamber was switched off, which resulted in 4 by an increase in temperature T _{∞ of} the surroundings of an outer leather covering of the steering wheel rim of the steering wheel.

The regulation of the steering wheel heating, which is based on the in 3 cascade control shown, uses, as explained above, a target temperature T _{sensor, target determined on the temperature sensor based on a specified temperature T reference, target of} the reference, with the target temperature T _{sensor, target} according to the invention not only being dependent on the specified temperature T _{reference, target} of the reference, but also on the ambient temperature T _{∞ of} the reference. The target temperature T _{sensor, target} falls according to 4 with increasing ambient temperature T _∞ . The actual sensor temperature _sensor T rises until it settles to the target temperature T _{sensor target.} Following the _sensor temperature T sensor , the temperature T _{reference of} the reference also increases until it reaches the specified target temperature T _{reference , target} and keeps it within specified tolerance limits T ^- and T ^{+ .} The temperature of the T _reference of the reference was measured with a plurality of temperature sensors on the cover and independent of the steering wheel and the control-measuring device. T _reference in 4 is the mean value of the temperature determined with the sensors.

5 refers to a measurement, according to which the steering wheel with the in the steering wheel rim integrated steering wheel heating is placed in a cold chamber after the start of the measurement. Correspondingly, the ambient temperature T _∞ falls abruptly, whereupon the target temperature T _{sensor, desired} at the temperature sensor rises abruptly. The actual temperature T _sensor at the temperature sensor follows; such that the temperature T _{reference of} the reference settles at a temperature value within the specified tolerance limits T ^- and T ⁺ . In 5 In addition, the result of a comparison measurement that was carried out with a conventional control system and which, in particular, does not use a correction variable that is dependent on _{the ambient temperature T ∞ of the reference, is shown.} The temperature T _reference, conv of the reference then falls below the minimum value T ^{- of} the tolerance range T ^- , T ^{+ as} the ambient temperature drops and remains outside (below) this tolerance range.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017102688 A1 [0002]

Claims (15)

A method for operating a heater for heating a device of a motor vehicle, the device having a reference which at least partially covers the heater, with the steps: - specifying a temperature T _{reference, setpoint of} the reference (13); and - determining a temperature with the aid of at least one temperature sensor (15) which is arranged in or on the device, characterized by regulating the heating (14), a setpoint temperature T _{sensor, setpoint} at the temperature sensor (15) being used as the setpoint for the regulation is used, which is determined with the aid of a correction variable Δ from the specified temperature T _{reference, target of} the reference (13), the correction variable Δ being determined by the specified temperature T _{reference, target of} the reference (13) and a temperature T _{∞ of} an environment of the Reference (13) depends outside the device. procedure after claim 1 , characterized in that the specified temperature T _{reference, target of} the reference (13) is a temperature on an outer side (131) of the reference (13). procedure after claim 1 or 2 , characterized in that the target temperature T _{sensor, target} at the temperature sensor (15) according to T _{sensor, target} = T _{reference, target} + Δ is determined. Method according to one of the preceding claims, characterized in that the correction variable Δ is determined according to Δ=(T _{reference, target} −T _∞ )*P, where P is a constant to be determined by a calibration measurement. Method according to one of the preceding claims, characterized in that the heating (14) is regulated with the aid of a continuous regulation (140). procedure after claim 5 , characterized in that the continuous control (140) includes a P control. Method according to one of the preceding claims, characterized in that the heating (14) is regulated with the aid of a cascaded regulation which has at least one master controller (141) with the target temperature T _{sensor, target} at the temperature sensor (15) as the target value and a slave controller (142) that uses a dependent on the desired temperature T _{sensor setpoint} target heat output P _target as a target value comprises. procedure after claim 7 , characterized in that the slave controller (142) generates a PWM signal as the output variable. Heating device for heating a device of a motor vehicle, in particular for carrying out the method according to one of the preceding claims, with - a heater (14) which can be arranged below a cover (13) of the device for heating the device; and - a unit for detecting a predetermined temperature T _{reference, setpoint of} the reference (13) and a temperature measured with at least one temperature sensor (15) arranged in or on the device, characterized by a controller (140) for controlling the heating (14) , wherein the controller is designed to use a temperature T _{sensor, target} at the temperature sensor (15) as the target value, which is determined with the aid of a correction variable Δ from the specified temperature T _{reference, target of} the reference (13), the correction variable being dependent on the predetermined temperature T _{reference, target of} the reference (13) and a temperature T _∞ an environment of the reference (13) depends outside of the device. heating device after claim 9 , characterized in that the temperature sensor (15) is an NTC sensor. heating device after claim 9 or 10 , characterized in that the heater (14) has at least one heating conductor or at least one heating mat (141). heating device after claim 11 , characterized in that the temperature sensor (15) is arranged in or on the heating element or the heating mat (141). Heating device according to one of claims 9 until 12 , characterized in that the cover (13) is at least partially made of leather or a plastic. Device for a motor vehicle, in particular a steering device or a seat, with a heating device according to one of claims 9 until 13 . device after Claim 14 , characterized in that the device is a steering device and the temperature sensor (15) of the heating device is arranged in a foam casing (12) of a skeleton (11) of the steering device or between the foam casing (12) and the cover (13). .

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