JP2008232503A - Temperature control device for steering wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature control device for a steering wheel capable of detecting failure of a Peltier element with high accuracy while suppressing increase of number of components. <P>SOLUTION: Temperature difference DTcs of a cooling target temperature value Tct and an initial temperature value Tcs is calculated. A temperature change threshold value is calculated on the basis of the relationship of the temperature difference DTcs and monotone nondecreasing, and a duration time threshold value is calculated on the basis of the relationship of the temperature difference DTcs and monotone nonincreasing. A temperature change ΔTc per a unit time is detected on the basis of the detected temperature, the duration time Δτdcl in a state that the temperature change ΔTc per unit time is smaller than the temperature change threshold value, is detected when a duty ratio is more than a prescribed value, and the failure of the Peltier element is judged when the duration time Δτdcl is more than the duration time threshold value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a temperature control device for a steering wheel.

Conventionally, as a temperature control device for a steering wheel, for example, a device described in Patent Document 1 is known. This device incorporates a Peltier element as a thermoelectric conversion element that generates and absorbs heat into the steering wheel, and detects the current temperature (actual temperature) of the steering wheel by a temperature sensor (thermistor) to obtain a predetermined temperature. As described above, the polarity of the voltage applied to the Peltier element is switched to select heating and cooling, and the temperature of the steering wheel is adjusted by on / off (intermittent) control of the applied voltage.
JP-A-60-88679

  By the way, in such a configuration in which the temperature of the steering wheel is adjusted by controlling the voltage applied to the Peltier element, it has been studied to detect a failure of the Peltier element. For example, a voltage drop generated by a resistance for detecting an energization current of the Peltier element is monitored by a comparator, and the Peltier element is determined according to the match / mismatch between the state of the voltage output by the comparator and the state of the voltage applied to the Peltier element. It has been proposed to judge normality / failure. This is because the Peltier element is electrically a resistor, and the waveform of the current flowing through the Peltier element, that is, the waveform of the voltage output from the comparator is normally matched (synchronized) with the waveform of the applied voltage. Is. However, in this case, the number of parts is increased by the amount of the circuit (comparator or the like) related to the failure detection, and thus the cost is inevitably increased. In addition, it is necessary to secure a space on the board for mounting a circuit related to failure detection, which increases the cost of the board.

  An object of the present invention is to provide a temperature control device for a steering wheel that can accurately detect a failure of a Peltier element while suppressing an increase in the number of parts.

  In order to solve the above problems, the invention according to claim 1 includes a Peltier element provided in a steering wheel, and a temperature detecting means for detecting the temperature of the steering wheel, and the temperature adjusting action by the Peltier element. In the steering wheel temperature control device for controlling the temperature of the steering wheel to the target temperature by setting the duty ratio of the voltage applied to the Peltier element in a relationship between the strength of the motor and the monotonic non-decreasing, at the start of the target temperature and temperature adjustment A calculating means for calculating a temperature difference between the temperatures detected by the temperature detecting means; a first calculating means for calculating a temperature change threshold value in a relationship of non-decreasing monotonously with the calculated temperature difference; and the calculated temperature difference. And a second calculating means for calculating a duration threshold value in a monotonically non-increasing relationship, and based on the temperature detected by the temperature detecting means. A change detection unit for detecting a temperature change per unit time, and when the duty ratio is larger than a predetermined value, the temperature change per unit time detected by the change detection unit is the temperature change A duration detecting unit for detecting a duration when the state is smaller than a threshold; and a failure of the Peltier element is determined when the duration detected by the duration detecting unit is greater than the duration threshold. The gist of the invention is that it comprises a judging means.

  In general, when the temperature adjustment action by the Peltier element is started to control the temperature of the steering wheel to the target temperature, the temperature of the steering wheel, that is, the temperature detected by the temperature detecting means, gradually increases with time. The target temperature is approached. At this time, even if the Peltier element is normal, the temperature change per unit time increases as the temperature detected by the temperature detecting means at the start of the target temperature and temperature adjustment, that is, the temperature difference between the initial temperatures increases. Show the trend. Further, the smaller the temperature difference between the initial temperature and the target temperature, the longer the duration when the temperature change per unit time is smaller. On the other hand, if the Peltier element is faulty (abnormal), the temperature of the steering wheel, i.e., the temperature detected by the temperature detecting means, is almost in the vicinity of the initial temperature even if the temperature adjusting action by the Peltier element is started. To do.

  According to this configuration, the temperature change threshold and the duration threshold are calculated by reflecting the temperature change per unit time and the tendency of the duration. The failure (abnormality) of the Peltier element can be accurately determined based on the threshold determination for the temperature change per unit time by the temperature change threshold and the threshold determination for the duration by the duration threshold. . Further, since the failure of the Peltier element can be detected (determined) basically by only the arithmetic processing by the temperature control device, for example, a circuit (such as a comparator) relating to the failure detection can be omitted.

  According to the first aspect of the present invention, it is possible to provide a temperature control device for a steering wheel that can accurately determine a failure of a Peltier element without using a circuit relating to failure detection.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a steering wheel according to the present embodiment. As shown in the figure, the steering wheel includes a mounting portion 11 attached to a steering shaft of a vehicle, a plurality (four) of spoke portions 12 extending radially from the mounting portion 11, and the spoke portions. And an annular ring portion 13 for connecting the 12 tip portions.

  The ring portion 13 includes an annular rim portion 21 as a heat storage body made of, for example, aluminum. As shown in an enlarged view in FIG. 1, the rim portion 21 includes a plurality (12 pieces) of Peltier to match the left and right grip portions formed on the ring portion 13 between the spoke portions 12 that are vertically adjacent to each other. An element 22 is provided. Six of these twelve Peltier elements 22 are arranged in the left and right grip portions of the ring portion 13. The six Peltier elements 22 arranged in each grip portion are electrically connected in series to form a Peltier element assembly 23. Each Peltier element assembly 23 is thermally conductively connected to the rim portion 21 at a corresponding grip portion. The six Peltier elements 22 constituting each Peltier element assembly 23 are arranged in three on the outer peripheral side and the inner peripheral side of the ring portion 13.

  In each Peltier element assembly 23, a heat transfer plate 24 made of, for example, copper is attached to the three Peltier elements 22 arranged on the outer peripheral side and the inner peripheral side of the ring portion 13. Each heat transfer plate 24 is connected to the corresponding three Peltier elements 22 in a heat conductive manner.

  The rim portion 21 is covered with a skin 25 made of, for example, real leather or synthetic leather, together with the Peltier element assembly 23 (Peltier element 22) and the heat transfer plate 24.

  As shown in FIG. 1, the Peltier element assembly 23 of each grip portion is electrically connected to a control unit 31 having a microcomputer, and responds according to the energization output from the control unit 31. Heat or cool the surface of the grip part. Specifically, for example, when energized and output to cool the surface of the grip portion, the Peltier element assembly 23 absorbs heat from the heat transfer plate 24 and uses the heat capacity of the rim portion 21 to rim portion 21. Stores and dissipates heat. Thereby, the heat | fever of the outer skin 25 moves to the rim | limb part 21, and the surface of a grip part is cooled.

  Each grip portion is provided with a thermistor 32 as temperature detecting means for detecting the temperature. The control unit 31 detects the temperature of the corresponding grip portion by the temperature signal input from each thermistor 32, and controls the energization output to the Peltier element assembly 23 according to the detected temperature. That is, the control unit 31 individually adjusts the temperature of the left and right grip portions. In the ring portion 13, it goes without saying that each grip portion forms a temperature adjustment region by the Peltier element assembly 23 or the like.

Next, the electrical configuration of the control unit 31 will be described with reference to the circuit diagram of FIG.
As shown in the figure, the control unit 31 includes a microcomputer 33 that stores various control programs and executes the control programs. The microcomputer 33 is electrically connected to a plus terminal of a battery 35 having a predetermined voltage VB (for example, 12V) through a constant voltage power supply circuit 34, and is grounded to the ground GND. The constant voltage power circuit 34 supplies the microcomputer 33 with a predetermined voltage Vcc (for example, 5V) as a power source.

  The microcomputer 33 is electrically connected to the Peltier element assembly 23 and the thermistor 32 disposed in the left and right grips, respectively. In addition, since the electrical connection structure with the microcomputer 33 is the same in the left and right grip portions, hereinafter, the electrical connection structure with the Peltier element assembly 23 and the thermistor 32 disposed in the left grip portion will be described. This will be described as a representative, and the right grip portion will be denoted by the same reference numerals and detailed description thereof will be omitted.

  The microcomputer 33 is connected to the bases of NPN transistors Tr1 and Tr2 via resistors Rb1 and Rb2, respectively. The collectors of these transistors Tr1 and Tr2 are connected to one of the coils L1 and L2 constituting the relay 36. Each point is connected. The emitters of the transistors Tr1 and Tr2 are grounded to the ground GND.

  The relay 36 includes a pair of contacts a1 and a2 that are electrically connected to the positive terminal of the battery 35, and the contacts a1 and a2 are connected to the other connection point of the coils L1 and L2, respectively. Yes. The relay 36 includes a pair of contacts b1 and b2, and the contacts b1 and b2 are connected to the drain of the N-type power FET 37. The gate of the power FET 37 is connected to the microcomputer 33, and the source thereof is grounded to the ground GND.

  Further, the relay 36 includes a pair of movers c1 and c2 for switching the contacts between the contacts a1 and b1 and between the contacts a2 and b2. These movers c1 and c2 are connected to both connection points P1 and P2 of the Peltier element assembly 23, respectively. One mover c1 is normally connected to the contact b1, and when the transistor Tr1 is turned on by the microcomputer 33 and the coil L1 is energized, the mover c1 is driven by the coil L1. The contact a1 (predetermined voltage VB) is connected. Similarly, the other mover c2 is normally connected to the contact b2, and when the transistor Tr2 is turned on by the microcomputer 33 and the coil L2 is energized, the mover c2 is connected to the coil L2. It is driven and connected to the contact a2 (predetermined voltage VB).

  Therefore, for example, when one of the movable elements c1 is connected to the contact point a1 by driving the coil L1, when the power FET 37 is turned on by the microcomputer 33, the contact point b2 is grounded to the ground GND via the power FET 37. In the Peltier element assembly 23, a current flows from one connection point P1 connected to the mover c1 to the other connection point P2 connected to the mover c2. In the present embodiment, the surface of the grip portion is set to be cooled when a current flows through the Peltier element assembly 23 in the above-described direction.

  Further, when the power FET 37 is turned on by the microcomputer 33 when the other movable element c2 is connected to the contact a2 by driving the coil L2, the contact b1 is grounded to the ground GND via the power FET 37. In the Peltier element assembly 23, a current flows from the other connection point P2 connected to the mover c2 to one connection point P1 connected to the mover c1. In the present embodiment, the surface of the grip portion is set to be heated when a current flows through the Peltier element assembly 23 in the above-described direction.

  The microcomputer 33 outputs a pulse signal having a fixed period to the gate of the power FET 37, and changes the on-time ratio of the pulse signal in the fixed period, that is, the duty ratio of the voltage applied to the Peltier element assembly 23. Thus, the strength of the cooling or heating action by the Peltier element assembly 23 is controlled.

  The thermistor 32 has one connection point connected to a predetermined voltage Vcc via a resistor Ru, and the other connection point connected to the ground GND. A connection point C between the thermistor 32 and the resistor Ru is connected to the microcomputer 33. The microcomputer 33 inputs the voltage division of the predetermined voltage Vcc (voltage at the connection point C) by the resistor Ru and the thermistor 32 as a temperature signal, and detects the temperature (detected temperature T) of the grip portion where the thermistor 32 is provided. .

  Further, a battery voltage detection unit 38 is connected to the microcomputer 33. The battery voltage detection unit 38 includes resistors Rc and Rd connected in series, and is connected to the microcomputer 33 at a connection point C1 between the resistors Rc and Rd. The remaining connection point of the resistor Rc is connected to the predetermined voltage VB (the positive terminal of the battery 35), and the remaining connection point of the resistor Rd is grounded to the ground GND. The microcomputer 33 receives the divided voltage (voltage at the connection point C1) of the predetermined voltage VB by the resistors Rc and Rd as a battery voltage signal, and detects the voltage of the battery 35 (+ B power supply voltage).

  Next, the relationship between the polarity of the applied voltage to the Peltier element assembly 23 and the action thereof will be described collectively based on the list shown in FIG. As shown in the figure, when the connection point P1 of the Peltier element assembly 23 is connected to the predetermined voltage VB on the positive side and the connection point P2 is connected to the ground GND on the negative side in the above-described manner, The action of the assembly 23 is cooling. On the other hand, when the connection point P1 of the Peltier element assembly 23 is connected to the ground GND on the negative side and the connection point P2 is connected to the predetermined voltage VB on the positive side, the action of the Peltier element assembly 23 is heated. As described above, the cooling or heating action by the Peltier element assembly 23 is switched depending on the polarity of the applied voltage. Needless to say, the polarity of the applied voltage is switched by selectively driving the relay 36 (coils L1 and L2) by the transistors Tr1 and Tr2.

  Next, the manner in which the voltage is applied to the Peltier element assembly 23 will be generally described. FIG. 4 is a time chart showing the applied voltage in each of cooling and heating, and FIG. 5 shows the duty ratio of the applied voltage in each of cooling and heating and the strength of the cooling and heating action by the Peltier element assembly 23. It is explanatory drawing which shows the relationship. In FIG. 4, the polarity of the applied voltage during cooling is represented on the plus side.

  As shown in FIG. 4, for example, the voltage applied between the two connection points P1 and P2 of the Peltier element assembly 23 at the time of cooling is an on / off waveform having a predetermined period tc. The predetermined voltage VB is applied during the energization time τc. This is for supplying a voltage of about 2V (= 12 / 6V) with excellent heat absorption efficiency to each Peltier element 22 to suppress the loss. The percentage (= τc / tc × 100) [%] of the value obtained by dividing the energization time τc by the period tc is the duty ratio Dc of the voltage applied to the Peltier element assembly 23 during cooling. The microcomputer 33 controls the strength of the cooling action by the Peltier element assembly 23 by changing the duty ratio Dc.

  On the other hand, the voltage applied between the connection points P1 and P2 of the Peltier element assembly 23 during heating has an on / off waveform having a predetermined period th, and has a reverse polarity during the energization time τh in each period th. A predetermined voltage −VB is applied. Note that the percentage (= τh / th × 100) [%] of the value obtained by dividing the energization time τh by the period th is the duty ratio Dh of the voltage applied to the Peltier element assembly 23 during heating. The microcomputer 33 controls the intensity of the heating action by the Peltier element assembly 23 by changing the duty ratio Dh.

  As shown in FIG. 5, for example, the strength of the cooling action by the Peltier element assembly 23 is such that the duty ratio Dc of the applied voltage at the time of cooling is increased or decreased between 0 to 100%. It is continuously controlled so that there is no at 0% and maximum at 100%. That is, the duty ratio Dc is set according to the relationship between the strength of the temperature adjusting action (cooling action) by the Peltier element assembly 23 and monotonous non-decreasing. Similarly, the intensity of the heating action by the Peltier element assembly 23 becomes zero or less at 0% of the duty ratio Dh by increasing or decreasing the duty ratio Dh of the applied voltage during heating between 0 and 100%. It is continuously controlled so as to be maximum at 100%. That is, the duty ratio Dh is set according to the relationship between the strength of the temperature adjusting action (heating action) by the Peltier element assembly 23 and monotonous non-decreasing.

  The energization control of the Peltier element assembly 23 based on the duty ratios Dc and Dh is performed when the + B power supply voltage detected by the battery voltage detector 38 is within a predetermined operating voltage range (for example, 10 to 16 V). It is executed and stopped outside the predetermined operating voltage range.

  Next, how the duty ratios Dc and Dh are set in this embodiment will be described. Both the duty ratios Dc and Dh are basically set so as to change in a proportional relationship with a change in the temperature of the steering wheel in each corresponding predetermined temperature range of the steering wheel (grip part). The duty ratios Dc and Dh are controlled by executing a control program by the microcomputer 33.

  First, the setting aspect of the duty ratio Dc during the cooling operation will be described. FIG. 6 is a map showing the relationship between the detected temperature T (steering wheel temperature) during the cooling operation and the duty ratio Dc. As shown in the figure, when the detected temperature T is in a range from a predetermined temperature value Tc0 (for example, 43.3 ° C) to a predetermined temperature value Tcc (for example, 60 ° C), the duty ratio Dc is 0%. From 100 to 100% (proportional control). When the detected temperature T is lower than the predetermined temperature value Tc0 (T <Tc0), the duty ratio Dc is set to 0%, and when the detected temperature T is higher than the predetermined temperature value Tcc ( For T> Tcc), the duty ratio Dc is set to 100%. A predetermined duty ratio Dct (for example, 40%) for holding the cooling target temperature value Tct is set at a cooling target temperature value Tct (for example, 50 ° C.) that is a target temperature during the cooling operation. .

Next, transition of the detected temperature T (steering wheel temperature) and the duty ratio Dc in the present embodiment will be described.
7A and 7B, the detected temperature T at the start of cooling of the steering wheel (actually the average temperature of the detected temperature T by the left and right thermistors 32, hereinafter referred to as the initial temperature value Tcs) is increased (for example, It is a time chart which shows transition of detected temperature T and duty ratio Dc at the time of 85 degreeC). FIGS. 8A and 8B are time charts showing changes in the detected temperature T and the duty ratio Dc when the initial temperature value Tcs is low (for example, 70 ° C.). As shown in the figure, when cooling is started at time τcs1, τcs2, the duty ratio Dc is set to 100% until time τcc1, τcc2 when the detected temperature T reaches the temperature value Tcc. A strong cooling action is performed by the Peltier element assembly 23 with a duty ratio Dc of 100%.

  After the detected temperature T reaches the temperature value Tcc, the duty ratio Dc is gradually decreased until the detected temperature T reaches the cooling target temperature value Tct until the time τct1, τct2, and the Peltier element assembly 23 responds to the duty ratio Dc. Cooling action is performed. 7 and 8 also show the time Δτcst1 (= τct1−τcs) and Δτcst2 (= τct2−τcs2) from the start of cooling until reaching the cooling target temperature value Tct.

  As is apparent from FIGS. 7 and 8, as the temperature difference between the cooling target temperature value Tct and the initial temperature value Tcs is larger, the temperature change per unit time (temperature decrease) immediately after the start of cooling tends to increase. It is confirmed to show. Further, it is confirmed that the smaller the temperature difference between the cooling target temperature value Tct and the initial temperature value Tcs, the longer the duration when the temperature change per unit time is smaller.

  Next, the setting aspect of the duty ratio Dh during the heating operation will be described. The duty ratio Dh is set by the same process as the duty ratio Dc, except that the predetermined temperature range and the target temperature change direction are different corresponding to the heating action.

  FIG. 9 is a map showing the relationship between the detected temperature T (steering wheel temperature) during the heating operation and the duty ratio Dh. As shown in the figure, when the detected temperature T is in a range from a predetermined temperature value Th0 (for example, 34.3 ° C.) to a predetermined temperature value Thc (for example, 20 ° C.), the duty ratio Dh is 0%. From 100 to 100% (proportional control). When the detected temperature T is higher than the predetermined temperature value Th0 (T> Th0), the duty ratio Dh is set to 0%, and when the detected temperature T is lower than the predetermined temperature value Thc ( For T <Thc), the duty ratio Dh is set to 100%. Note that a predetermined duty ratio Dht (for example, 30%) for holding the heating target temperature value Tht is set at a heating target temperature value Tht (for example, 30 ° C.), which is a target temperature during the heating operation. .

Next, transition of the detected temperature T (steering wheel temperature) and the duty ratio Dh in the present embodiment will be described.
10A and 10B, the detected temperature T at the start of heating of the steering wheel (actually, the average temperature of the detected temperature T by the left and right thermistors 32, hereinafter referred to as the initial temperature value Ths) is low (for example, It is a time chart which shows transition of detection temperature T and duty ratio Dh at the time of -10 degreeC. FIGS. 11A and 11B are time charts showing transitions of the detected temperature T and the duty ratio Dh when the initial temperature value Ths is high (for example, 10 ° C.). As shown in the figure, when heating is started at time τhs1, τhs2, the duty ratio Dh is set to 100% until time τhc1, τhc2 when the detected temperature T reaches the temperature value Thc. Then, a strong heating action is performed by the Peltier element assembly 23 with a duty ratio Dh of 100%.

  After the detected temperature T reaches the temperature value Thc, the duty ratio Dh is gradually decreased until the time τht1 and τht2 when the detected temperature T reaches the heating target temperature value Tht, and the Peltier element assembly 23 responds to the duty ratio Dh. A heating action is performed. Accordingly, in FIGS. 10 and 11, times Δτhst1 (= τht1−τhs) and Δτhst2 (= τht2−τhs2) from the start of heating to reaching the heating target temperature value Tht are also shown.

  As is clear from FIGS. 10 and 11, the larger the temperature difference between the heating target temperature value Tht and the initial temperature value Ths, the greater the temperature change per unit time (temperature rise) immediately after the start of heating. It is confirmed that it shows a tendency. Further, it is confirmed that the smaller the temperature difference between the heating target temperature value Tht and the initial temperature value Ths, the longer the duration when the temperature change per unit time is smaller.

  Here, a failure detection mode of the Peltier element assembly 23 (Peltier element 22) in the present embodiment will be described. In addition, as a cause of a failure here, the disconnection of the Peltier device assembly 23 (or each Peltier device 22 which comprises this) and the disconnection of the connection wiring system are mentioned, for example. Failure detection of the Peltier element assembly 23 is performed by executing a control program by the microcomputer 33.

  First, various factors that can be used for detecting a failure of the Peltier element assembly 23 (Peltier element 22) will be described in view of the above-described transition of the detected temperature T during temperature adjustment (cooling / heating) of the steering wheel.

FIG. 12 is an explanatory diagram showing various factors for determining the failure of the Peltier element assembly 23 and the basis for selecting the factors.
As shown in the figure, the factor (1) is that the duty ratios Dc and Dh of the applied voltage are not less than predetermined values (for example, 95%) Dcth and Dhth. This is because a sufficiently large cooling / heating action by the Peltier element assembly 23 is preferable for failure detection because a clear change occurs in the transition of the detected temperature T. It should be noted that the + B power supply voltage detected by the battery voltage detector 38 is within a predetermined operating voltage range (for example, 10 to 16 V), in other words, the influence of the voltage fluctuation of the battery 35 is suppressed. This is a prerequisite.

  The factor (2) is that the temperature difference DTc or DTh between the detected temperature T (actual temperature) and the cooling target temperature value Tct or the heating target temperature value Tht is larger than the temperature difference threshold value DTcth or DThth related to the magnitude comparison. . This is because especially when the temperature difference DTc or DTh is large, such as immediately after the start of temperature control, the duty ratios Dc and Dh become large and satisfy the factor (1). That is, if the Peltier device assembly 23 normally performs a sufficiently strong cooling / heating action corresponding to this state, a clear change occurs in the transition of the detected temperature T, which is preferable for failure detection.

  Further, the factor (3) is that the temperature change ΔTc or ΔTh per unit time (for example, 1 second) of the detected temperature T (actual temperature) is smaller than the temperature change threshold ΔTcth or ΔThth related to the magnitude comparison. This suggests that when no temperature change (temperature decrease or temperature increase) due to the cooling / heating action of the Peltier element assembly 23 has occurred, the Peltier element assembly 23 is not operating, that is, has failed. It is.

  Furthermore, the factor (4) is that the time (duration) Δτdc or Δτdh in which the state satisfying all the factors (1) to (3) continues continuously is greater than or equal to the duration threshold value Δτdcth or Δτdhth related to the magnitude comparison. There is. This is a method for determining that the Peltier element assembly 23 is not operating, that is, has failed, by continuously satisfying all the factors (1) to (3) for a sufficiently long time. This is because the detection accuracy can be improved.

  Next, the various factors (1) to (4) described above, that is, the factors relating to the output state of the energization control of the Peltier element assembly 23 (Peltier element 22), the state of the detected temperature T, and the change state thereof are described as follows. A mode used for failure detection will be described by reflecting it in the characteristics of the transition.

  FIGS. 13A, 13B and 13C show the temperature difference DTcs between the cooling target temperature value Tct and the initial temperature value Tcs during the cooling of the steering wheel, the temperature difference threshold value DTcth, the temperature change threshold value ΔTcth, and the duration threshold value Δτdcth. It is a map which shows the relationship with each. 14A, 14B, and 14C show the temperature difference DThs between the heating target temperature value Tht and the initial temperature value Ths, the temperature difference threshold value DThth, the temperature change threshold value ΔThth, and the duration time when the steering wheel is heated. It is a map which shows the relationship with threshold value (DELTA) (tau) dhth, respectively.

  As shown in FIGS. 13A and 14A, the temperature difference thresholds DTcth and DThth change in a monotonous non-decreasing relationship with respect to the temperature differences DTcs and DThs. This is because, as the temperature differences DTcs and DThs from the initial temperature values Tcs and Ths are larger, the temperature differences DTc and DTh from the detected temperature T tend to become larger immediately after the start of the temperature adjustment, and therefore correspond to this. This is because increasing the temperature difference thresholds DTcth and DThth results in more accurate failure detection.

  Further, as shown in FIGS. 13B and 14B, the temperature change thresholds ΔTcth and ΔThth change in a monotonically non-decreasing relationship with respect to the temperature differences DTcs and DThs. This is because, as the temperature difference DTcs, DThs from the initial temperature values Tcs, Ths increases, the temperature change ΔTc, ΔTh tends to increase especially immediately after the start of temperature adjustment. This is because increasing the threshold values ΔTcth and ΔThth results in more accurate failure detection.

  Further, as shown in FIGS. 13C and 14C, the duration threshold values Δτdcth and Δτdhth change in a monotonically non-increasing relationship with respect to the temperature differences DTcs and DThs. This is because the smaller the temperature differences DTcs and DThs from the initial temperature values Tcs and Ths, the smaller the temperature changes ΔTc and ΔTh tend to continue for a longer time, and accordingly the duration threshold values Δτdcth, This is because increasing Δτdhth results in more accurate failure detection. In other words, if the temperature difference DTcs, DThs is large, a large temperature change ΔTc, ΔTh can be obtained in a short time immediately after the start of temperature adjustment, so that the state where the temperature change ΔTc, ΔTh is small is continued for a short time. Even so, a failure can be detected.

Next, the transition of the detected temperature T at the time of failure of the Peltier element assembly 23 and the failure detection mode will be described.
FIG. 15 is a graph showing the transition of the detected temperature T when the initial temperature value Tcs during cooling is high and the temperature difference DTcs is large, as in FIG. A normal time is indicated by a broken line, and a time when the Peltier element assembly 23 is broken is indicated by a solid line. Here, when cooling is started at time τcs1, the temperature change ΔTc appears large if it is normal, whereas the temperature change ΔTc appears small during a failure. Further, at the time of failure, a temperature difference DTc with the detected temperature T at the time of determination appears greatly. Therefore, when the temperature difference DTcs is large, even if the duration Δτdc1 is short, the temperature change ΔTc shows a significant difference between the normal time and the failure time, and it is confirmed that mutual discrimination is possible. . Note that the slight temperature change occurs even at the time of failure because it is affected by a decrease in the cabin temperature due to cooling or window opening.

  On the other hand, FIG. 16 is a graph showing the transition of the detected temperature T when the initial temperature value Tcs during cooling is lower and the temperature difference DTcs is small as in FIG. A time when the control is normal is indicated by a broken line, and a time when the Peltier element assembly 23 is broken is indicated by a solid line. Here, when cooling is started at time τcs2, the temperature change ΔTc appears to some extent although it is small if normal, whereas the temperature change ΔTc appears to be minimal at the time of failure. Further, at the time of failure, the temperature difference DTc from the detected temperature T at the time of determination appears small. Therefore, when the temperature difference DTcs is small, by making the duration Δτdc2 longer, the difference in temperature change ΔTc between the normal time and the failure time can be made obvious and mutual discrimination is possible. That is confirmed.

  FIG. 17 is a graph showing the transition of the detected temperature T when the initial temperature value Ths during heating is low and the temperature difference DThs is large as in FIG. A time when the control is normal is indicated by a broken line, and a time when the Peltier element assembly 23 is broken is indicated by a solid line. Here, when heating is started at time τhs1, if it is normal, the temperature change ΔTh appears large, whereas at the time of failure, the temperature change ΔTh appears small. Further, at the time of failure, a large temperature difference DTh from the detected temperature T at the time of determination appears. Therefore, when the temperature difference DThs is large, even if the duration time Δτdh1 is short, the temperature change ΔTh shows a significant difference between the normal time and the failure time, and it is confirmed that mutual discrimination is possible. . Note that the slight temperature change occurs even at the time of failure because it is affected by an increase in the cabin temperature due to heating.

  On the other hand, FIG. 18 is a graph showing the transition of the detected temperature T when the initial temperature value Ths during heating is high and the temperature difference DThs is small, as in FIG. A time when the control is normal is indicated by a broken line, and a time when the Peltier element assembly 23 is broken is indicated by a solid line. Here, when heating is started at time τhs2, the temperature change ΔTh appears to some extent although it is small if normal, whereas the temperature change ΔTh appears to be minimal at the time of failure. Further, at the time of failure, the temperature difference DTh from the detected temperature T at the time of determination appears small. Therefore, when the temperature difference DThs is small, by making the duration Δτdh2 longer, the difference in temperature change ΔTh between the normal time and the failure time can be made obvious, and mutual discrimination is possible. That is confirmed.

  As described above, when the temperature differences DTcs and DThs are large, the temperature difference threshold values DTcth and DThth and the temperature change threshold values ΔTcth and ΔThth are set large, and the duration threshold values Δτdcth and Δτdhth are set small, and conversely, the temperature difference DTcs. , DThs is small, the temperature difference threshold values DTcth, DThth and the temperature change threshold values ΔTcth, ΔThth are set small, and the continuous time threshold values Δτdcth, Δτdhth are set large, so that the failure detection can be performed regardless of the cooling / heating time. Increases accuracy.

Next, a control mode and a failure determination mode of the detected temperature T by the microcomputer 33, that is, the temperature of the steering wheel will be described generally.
FIG. 19 is a flowchart showing the main routine. As shown in the figure, when this control is activated, various initialization processes are performed (step S1), and the current detected temperature T is read as initial temperature values Tcs and Ths (step S2). Then, temperature differences DTcs, DThs between the initial temperature values Tcs, Ths and the target temperature values Tct, Tht at the time of cooling / heating are calculated (step S3: calculation means).

  Next, based on the temperature differences DTcs and DThs, according to the maps of FIG. 13A and FIG. 14A, the temperature difference regarding the temperature difference DTc and DTh between the detected temperature T and the target temperature values Tct and Tht during cooling and heating. Threshold values DTcth and DThth are calculated (step S4). Further, based on the temperature differences DTcs and DThs, temperature change thresholds ΔTcth and ΔThth relating to the temperature changes ΔTc and ΔTh of the detected temperature T are calculated according to the maps of FIGS. 13B and 14B (step S5: First calculation means). Further, based on the temperature differences DTcs and DThs, duration threshold values Δτdcth and Δτdhth relating to the durations Δτdc and Δτdh are calculated according to the maps of FIGS. 13C and 14C (step S6: second calculation means).

  Subsequently, various processes of the main routine are performed (step S7), and the presence / absence of failure information of the Peltier element 22 (Peltier element assembly 23) / wiring system stored in the inside (memory) is determined (step S8). If it is determined that there is no failure information, an energization control process for the Peltier element 22 is performed (step S9), a failure determination process is performed (step S10), and the process returns to step S7 and the same process is repeated. If it is determined in step S8 that there is failure information, the process returns to step S7 and only the various processes of the main routine are repeated.

  FIG. 20 is a flowchart showing an energization control processing mode of the Peltier element 22 in step S9. As described above, the temperature control of the left and right grip portions is performed separately, but basically the same processing is performed by paraphrasing the left side to the right side. Therefore, in the following, temperature control of the left grip portion will be described as a representative, and detailed description of the right grip portion will be omitted.

  As shown in the figure, when the process proceeds, the direction of temperature adjustment (cooling or heating) is determined based on the magnitude relationship between the initial temperature values Tcs and Ths and a predetermined temperature (for example, 50 ° C.) ( Step S11).

  If it is determined that the cooling is performed in step S11, the left relay 36 is set in a cooling energization state (step S12). Specifically, one of the coils L1 of the relay 36 is driven by the transistor Tr1, and the polarity of the applied voltage is switched so that a cooling action is performed by the Peltier element assembly 23. And the process for controlling the temperature of the left grip part to the cooling target temperature value Tct is performed (step S13).

  That is, the current + B power supply voltage is read (step S14), and it is determined whether the + B power supply voltage is within the predetermined operating voltage range (step S15). When it is determined that the + B power supply voltage is within the predetermined operating voltage range, that is, the influence of the voltage fluctuation of the battery 35 is suppressed, the detected temperature T of the left grip portion is detected (step S16). ). Based on the detected temperature T, the duty ratio Dc for the Peltier element assembly 23 of the left grip portion is calculated according to the map of FIG. 6 (step S17).

  Next, a pulse having the calculated duty ratio Dc is output to the left power FET 37 (step S18). Thereby, the Peltier element assembly 23 of the left grip part performs a cooling action with a strength according to the set duty ratio Dc.

  If it is determined in step S15 that the + B power supply voltage is not within the predetermined operating voltage range, that is, the influence of the voltage fluctuation of the battery 35 is large, the duty ratio Dc is set to 0% and the left-side power FET 37 Is stopped (step S18).

  On the other hand, if it is determined in step S11 that the heating is performed, the left-side relay 36 is set in a heating energization state (step S22). Specifically, the other coil L2 of the relay 36 is driven by the transistor Tr2, and the polarity of the applied voltage is switched so that the Peltier element assembly 23 performs a heating action. And the process for controlling the temperature of the left grip part to the said heating target temperature value Tht is performed (step S23).

  That is, the current + B power supply voltage is read (step S24), and it is determined whether the + B power supply voltage is within the predetermined operating voltage range (step S25). When it is determined that the + B power supply voltage is within the predetermined operating voltage range, that is, the influence of the voltage fluctuation of the battery 35 is suppressed, the detected temperature T of the left grip portion is detected (step S26). ). Based on the detected temperature T, the duty ratio Dh of the left grip portion with respect to the Peltier element assembly 23 is calculated according to the map of FIG. 9 (step S27).

  Next, a pulse having the calculated duty ratio Dh is output to the left power FET 37 (step S28). Thereby, the Peltier element assembly 23 of the left grip part performs a heating action with a strength according to the set duty ratio Dh.

  If it is determined in step S15 that the + B power supply voltage is not within the predetermined operating voltage range, that is, the influence of the voltage fluctuation of the battery 35 is large, the duty ratio Dc is set to 0% and the left-side power FET 37 Is stopped (step S18).

Then, when any one of steps S18, S19, steps S28, and S29 is performed, the process returns to the main routine and proceeds to the failure determination process of step S10.
FIG. 21 is a flowchart showing a failure determination processing mode of the Peltier element 22 in step S10. In the following, temperature control of the left grip portion will be described as a representative, and detailed description of the right grip portion will be omitted.

  As shown in the figure, when the process proceeds, the duty ratios Dc and Dh set in any one of steps S18, S19, S28, and S29 are read (step S31), and the duty ratios Dc and Dh are predetermined. It is determined whether the value is greater than or equal to the values Dcth and Dhth (step S32). When the duty ratios Dc and Dh are determined to be equal to or greater than the predetermined values Dcth and Dhth, the detected temperature T detected in steps S16 and S26 is read (step S33), and the detected temperature T and the temperature adjustment at that time ( Temperature differences DTc, DTh from target temperature values Tct, Tht corresponding to (cooling or heating) are calculated (step S34).

  Then, it is determined whether the temperature differences DTc, DTh from the detected temperature T are larger than the temperature difference threshold values DTcth, DThth calculated in step S4 (step S35), and are determined to be larger than the temperature difference threshold values DTcth, DThth. Then, temperature changes ΔTc and ΔTh per unit time of the detected temperature T are calculated (step S36: change detection means).

  Next, it is determined whether the temperature changes ΔTc and ΔTh per unit time are smaller than the temperature change thresholds ΔTcth and ΔThth calculated in step S5 (step S37), and are smaller than the temperature change thresholds ΔTcth and ΔThth. If it is determined, it is further determined whether the durations Δτdc and Δτdh for determining the failure are being counted (step S38).

  Here, if it is determined that the durations Δτdc and Δτdh are not being counted, the counting of the durations Δτdc and Δτdh is started (step S39). If it is determined that the durations are being counted, the current durations Δτdc and Δτdh are started. Is larger than (exceeded) the duration threshold values Δτdcth and Δτdhth calculated in step S6 (step S40: determination means).

  If it is determined that the current durations Δτdc and Δτdh are not greater than the duration threshold values Δτdcth and Δτdhth, the counting of the durations Δτdc and Δτdh is continued (step S41: duration detection means). On the other hand, if it is determined that the threshold values are larger than the duration threshold values Δτdcth and Δτdhth, the failure information of the left Peltier element 22 (Peltier element assembly 23) / wiring system is stored inside (memory) (step S42). Then, the output relay 36 to the left Peltier element 22 is completely stopped (step S43).

  Further, it is determined in step S32 that the duty ratios Dc, Dh are less than the predetermined values Dcth, Dhth, or in step S35, it is determined that the temperature differences DTc, DTh from the detected temperature T are not greater than the temperature difference thresholds DTcth, DThth, Alternatively, if it is determined in step S37 that the temperature changes ΔTc and ΔTh per unit time are not smaller than the temperature change thresholds ΔTcth and ΔThth, the counts of the durations Δτdc and Δτdh are reset (step S44).

  That is, the duty ratios Dc, Dh are equal to or greater than the predetermined values Dcth, Dhth, the temperature differences DTc, DTh with the detected temperature T are larger than the temperature difference thresholds DTcth, DThth, and the temperature change ΔTc per unit time , ΔTh are smaller than the temperature change thresholds ΔTcth, ΔThth, they are continuously counted as the durations Δτdc, Δτdh, and used for the determination (failure determination) in step S40.

Then, when any one of steps S39, S41, S43, and S44 is performed, the process returns to the main routine.
As described above in detail, according to the present embodiment, the following effects can be obtained.

  (1) In the present embodiment, the duty ratios Dc, Dh are equal to or greater than the predetermined values Dcth, Dhth, the temperature differences DTc, DTh from the detected temperature T are greater than the temperature difference thresholds DTcth, DThth, and unit time The Peltier element 22 (Peltier element assembly 23) is determined by threshold values of the durations Δτdc and Δτdh when the perceived temperature changes ΔTc and ΔTh are smaller than the temperature change thresholds ΔTcth and ΔThth based on the duration thresholds Δτdcth and Δτdhth. Can be accurately determined. Further, since the failure of the Peltier element 22 can be detected (determined) basically by only the arithmetic processing by the microcomputer 33 (control unit 31), for example, a circuit (comparator, etc.) relating to the failure detection can be omitted, thereby reducing the cost. can do.

Further, it is not necessary to secure a space (area) on the substrate for mounting a circuit related to failure detection, and the cost of the substrate can be reduced.
In addition, you may change the said embodiment as follows.

In the embodiment described above, the factor (2) relating to the failure detection of the Peltier element 22 (Peltier element assembly 23), that is, the determination in step S35 of FIG. 21 may be omitted.
-In the said embodiment, the number of the Peltier elements 22 is an example, for example, may be only one. However, a highly efficient applied voltage (about 2 V) is preferably set for each Peltier element 22.

Sectional drawing which shows one Embodiment of this invention. The circuit diagram which shows the same embodiment. The list figure which shows the relationship between the polarity of the applied voltage with respect to a Peltier device assembly, and its effect | action. The time chart which shows the applied voltage with respect to a Peltier device assembly. Explanatory drawing which shows the relationship between the duty ratio of an applied voltage, and the intensity | strength of the cooling and heating effect | action by a Peltier device assembly. The map which shows the relationship between the detected temperature at the time of a cooling action, and a duty ratio. (A) (b) is a time chart which shows transition of the detected temperature and duty ratio at the time of a cooling action when initial temperature is high. (A) (b) is a time chart which shows transition of the detected temperature and duty ratio at the time of cooling action when initial temperature is low. The map which shows the relationship between the detected temperature at the time of a heating effect | action, and a duty ratio. (A) (b) is a time chart which shows transition of the detected temperature and duty ratio at the time of a heating action when initial temperature is low. (A) (b) is a time chart which shows transition of the detected temperature and duty ratio at the time of a heating action when initial temperature is high. Explanatory drawing which shows the basis for selecting the various factors for determining a failure and the factors. (A) (b) (c) is a map which shows the relationship between the temperature difference with the initial temperature at the time of a cooling effect | action, a temperature difference threshold value with detection temperature, a temperature change threshold value, and a duration threshold value. (A) (b) (c) is a map which shows the relationship between the temperature difference with the initial temperature at the time of a heating effect | action, a temperature difference threshold value with detection temperature, a temperature change threshold value, and a duration threshold value. The time chart which shows the failure detection aspect at the time of the cooling action when initial temperature is high. The time chart which shows the failure detection aspect at the time of the cooling action when initial temperature is low. The time chart which shows the failure detection mode at the time of a heating action when initial temperature is low. The time chart which shows the failure detection aspect at the time of a heating action when initial temperature is high. The flowchart which shows the failure detection aspect of the embodiment. The flowchart which shows the failure detection aspect of the embodiment. The flowchart which shows the failure detection aspect of the embodiment.

Explanation of symbols

  22 ... Peltier element, 23 ... Peltier element assembly, 32 ... Thermistor (temperature detection means), 31 ... Control unit, 33 ... Microcomputer (calculation means, first calculation means, second calculation means, change detection means, duration detection) Means, judgment means).

Claims (1)

A Peltier element provided on the steering wheel; and a temperature detecting means for detecting the temperature of the steering wheel. In the steering wheel temperature control device for controlling the temperature of the steering wheel to a target temperature,
A calculation means for calculating a temperature difference between the target temperature and the temperature detected by the temperature detection means at the start of temperature adjustment;
First calculation means for calculating a temperature change threshold value in a relationship between the calculated temperature difference and monotonous non-decreasing;
A second calculating means for calculating a duration threshold value in a relationship between the calculated temperature difference and monotonous non-increasing;
Based on the temperature detected by the temperature detection means, a change detection means for detecting a temperature change per unit time;
When the duty ratio is larger than a predetermined value, a duration detection unit that detects a duration when the temperature change per unit time detected by the change detection unit is smaller than the temperature change threshold. When,
A temperature control apparatus for a steering wheel, comprising: determination means for determining a failure of the Peltier element when the duration detected by the duration detection means is greater than the duration threshold.

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