JP7403357B2 - Heater system, heater control device and heater control program - Google Patents

Description

The present invention relates to a heater system, a heater control device, and a heater control program, and more particularly, to a heater system, a heater control device, and a heater control program that control the temperature of a heated object heated by a heater based on the temperature detected by a temperature detection element. .

Systems using heaters have been proposed in various fields. One such heater system is a steering heater system in which a heater is incorporated into the steering wheel of an automobile. A heater system uses a temperature detection element that detects the temperature of a heated object in order to appropriately control the temperature of the heated object. In the heater system, the temperature of the heater is controlled based on the temperature information obtained from this temperature detection element. Examples of such heater systems are disclosed in Patent Documents 1 and 2.

The steering wheel described in Patent Document 1 includes a ring portion to be gripped during steering, a boss portion disposed approximately at the center of the ring portion, and a plurality of spoke portions connecting the ring portion and the boss portion. a core bar arranged so as to interconnect the ring part, the boss part, and the spoke part; the ring part of the core bar; and the spoke part near the ring part. a steering wheel body including a coating layer that covers a portion of the ring portion; and a heater unit that raises the temperature of at least a portion of the ring portion, the heater unit being a flexible sheet body. and a linear heater supported by the substrate, a heater main body whose outer surface side is covered with the cover layer of the coating layer, and the linear heater , a steering wheel configured to include a lead wire for power supply extending from the boss portion side, and a connection portion for connecting the ends of the core metal near the boundary portion between the ring portion and the spoke portion; Alternatively, a configuration for a steering wheel in which a storage recess is formed in the covering layer and is recessed from the periphery to accommodate the connection part, and the storage recess has an outer surface side disposed near the cover layer or the spoke part. It is covered by a front side material placed on the front side of the steering wheel made of parts.

The fixing device described in Patent Document 2 includes a fixing member and a pressure member that have an elastic layer and a release layer on a core bar, sandwich and convey a recording member, and heat at least one of the fixing member or the pressure member. a heating means; a temperature detecting means in contact with at least one of the fixing member or the pressure member; The fixing device includes a temperature control means for controlling the temperature to a predetermined target temperature, and fixes the unfixed image on the recording material to the recording material by applying heat and pressure. The target temperature is changed at or after the temperature detection means detects the lowest point temperature.

Japanese Patent Application Publication No. 2015-131537 Japanese Patent Application Publication No. 2003-302864

As described in Patent Document 1, in a steering wheel, many members are assembled in a limited area, so measures are taken such as providing a storage recess in the heater system to accommodate thick connection parts and the like. In such a steering wheel, it is difficult to provide a temperature detecting element such as a thermistor of the heater system on the ring portion of the steering wheel that is to be heated due to the discomfort of gripping the steering wheel and design problems. Therefore, it is difficult to incorporate a heater system into the steering wheel and directly measure the temperature of the ring portion to be heated using a temperature detection element. Therefore, in the steering wheel, it is conceivable to provide the temperature detection element in a portion other than the ring portion.

When the temperature detection element is provided at a position away from the heating target in this way, a temperature difference occurs between the actual temperature of the heating target and the detected temperature obtained from the temperature detection element. Therefore, temperature control of the heater is required that takes this temperature difference into consideration, but the technology described in Patent Document 1 directly detects the temperature of the heated object, and the temperature detection element is separated from the member to be heated. It cannot be applied to temperature control in a location.

For this reason, there is a problem in that even if Patent Documents 1 and 2 are used, it is not possible to perform highly accurate temperature control in a heater system applied to a steering wheel.

One aspect of the heater system according to the present invention includes a heater, a temperature detection element attached to a member to be heated to which the heater is attached, at a position different from a member directly heated by the heater, and a a heater control unit that controls power applied to the heater so that the detected temperature value approaches the temperature set value, and the heater control unit has a target temperature setting that indicates the temperature of the heated object. An initial target temperature set value indicating a temperature higher than the initial target temperature set value is set as the temperature set value, and power is supplied to the heater until the detected temperature value reaches the initial target temperature set value, and the detected temperature value is set as the initial target temperature set value. Power is supplied to the heater while decreasing the temperature set value so that the temperature detected as the detected temperature value decreases over time after reaching the target temperature set value, and the temperature set value is set to the target temperature set value. After the target temperature set value is matched, power is supplied to the heater according to the target temperature set value.

One aspect of the heater control device according to the present invention is a heater drive circuit that supplies power to the heater, and a temperature detection element that detects the target temperature of the heater and the temperature of a heated object that is overheated by the heater. A heater control device that outputs a control signal such that a temperature difference between the temperature value and a temperature correction amount register for storing a correction amount; a subtraction period register for storing a subtraction period setting value indicating the length of time for applying the corrected temperature setting value as the target temperature in place of the target temperature setting value; a temperature set value generation processing unit that outputs the target temperature based on the set values stored in the temperature register, the temperature correction amount register, and the subtraction period register; and a drive signal generation section that outputs a PWM signal whose duty ratio changes accordingly to the heater drive section. The initial target temperature set value is output as the target temperature until the detected temperature value reaches the initial target temperature set value, and after the detected temperature value reaches the initial target temperature set value, the initial target temperature set value is output as the target temperature. is gradually subtracted to the target temperature set value over a period corresponding to the subtraction period set value, and the value is output as the target temperature.

One aspect of the heater control program according to the present invention includes detection obtained by a temperature detection element that detects a target temperature of the heater and a temperature of a heated object to be overheated by the heater, in a heater drive circuit that supplies electric power to the heater. A heater control program executed in a semiconductor device that outputs a control signal such that a temperature difference between the temperature value and a temperature register, a temperature correction amount register that stores a temperature correction amount for the target temperature set value, and a subtraction period setting that indicates the length of time for applying the corrected temperature set value as the target temperature in place of the target temperature set value. and a subtraction period register for storing a value, and the heater control program is configured to maintain the initial target temperature set value until the detected temperature value reaches an initial target temperature set value obtained by adding the temperature correction amount to the target temperature set value. The target temperature set value is output as the target temperature, and after the detected temperature value reaches the initial target temperature set value, the initial target temperature set value is changed to the target temperature over a period corresponding to the subtraction period set value. A value gradually subtracted to the temperature set value is output as the target temperature, and a PWM signal whose duty ratio changes depending on the magnitude of the difference between the detected temperature value and the target temperature is output to the heater drive section.

According to the heater system, heater control device, and heater control program according to the present invention, it is possible to perform temperature control using a heater with high accuracy even if the temperature detection device is provided at a position away from the object to be heated.

1 is a block diagram of a heater system according to a first embodiment; FIG. FIG. 3 is a diagram illustrating the arrangement of the thermistors and the positional relationship with a ring portion in the heater system according to the first embodiment. 7 is a graph illustrating a difference in temperature control results depending on whether or not target temperature correction processing is performed in the heater system according to the first embodiment. FIG. 2 is a block diagram of a heater control section of the heater system according to the first embodiment. FIG. 3 is a diagram illustrating temperature parameters used in the heater control section of the heater system according to the first embodiment. It is a graph explaining the difference in temperature control results due to the difference in temperature before the start of temperature increase of the steering wheel. FIG. 2 is a block diagram of a heater control section of a heater system according to a second embodiment. 7 is a flowchart illustrating the operation of the heater system according to the second embodiment. FIG. 7 is a diagram illustrating a parameter correction method in the heater system according to the second embodiment. 7 is a graph illustrating a difference in temperature control results due to a difference in temperature before the start of temperature increase in the heater system according to the second embodiment.

Embodiment 1
For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In addition, each element described in the drawing as a functional block that performs various processes can be configured with a CPU (Central Processing Unit), memory, and other circuits in terms of hardware, and can be configured with a memory and other circuits in terms of software. This is accomplished by a program loaded into the computer. Therefore, those skilled in the art will understand that these functional blocks can be implemented in various ways using only hardware, only software, or a combination thereof, and are not limited to either. Note that in each drawing, the same elements are designated by the same reference numerals, and redundant explanations will be omitted as necessary.

Additionally, the programs described above can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer-readable media includes various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tape, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, and CDs. - R/W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). The program may also be provided to the computer on various types of transitory computer readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can provide the program to the computer via wired communication channels, such as electrical wires and fiber optics, or wireless communication channels.

In the following embodiments, a heater system applied to an automobile steering wheel will be described, but control in the heater system can also be used in other applications. FIG. 1 shows a block diagram of a heater system 1 according to the first embodiment. As shown in FIG. 1, the heater system 1 according to the first embodiment includes a battery 10, a switch SW, a control unit 20, a heater 31, and a temperature detection element (for example, a thermistor 32).

Battery 10 is a power source that supplies power to heater system 1 . The battery 10 is, for example, a battery mounted on a car. The switch SW switches whether or not to supply power to the control unit 20. For example, the switch SW is turned on and off in conjunction with an ignition switch.

The control unit 20 controls the power supplied to the heater 31 based on the detected temperature value detected by the thermistor 32. Here, in the heater system 1 according to the first embodiment, the heater 31 is provided at the lower part of the skin covering the ring part of the steering wheel for an automobile. Further, the thermistor 32 is provided at a spoke portion that connects the steering portion to the steering column. Therefore, the relationship between the installation positions of the heater 31 and thermistor 32 will be explained with reference to FIG. 2.

FIG. 2 is a diagram illustrating the arrangement of the thermistors and the positional relationship with the ring portion in the heater system according to the first embodiment. As shown in FIG. 2, the automobile steering wheel includes a ring portion 41, a boss portion 42, and spoke portions 43. The ring portion 41 is an annular member held by the user during driving, and its surface is covered with a covering member such as synthetic leather. The heater 31 used in the heater system 1 is provided between this covering member and a core bar serving as the core material of the ring portion. The boss portion 42 is a member for connecting the ring portion 41 to the steering column. The spoke portions 43 are members for connecting the ring portion 41 and the boss portion 42. The boss portion 42 and the spoke portions 43 have a metal core formed integrally with the metal core of the ring portion 41 . In the heater system 1, the thermistor 32 is attached to the core metal of the spoke portion 43. Further, the control unit 20 is also attached to a core metal of the spoke portions 43 or a cover member made of resin or the like that covers the core metal of the spoke portions 43 .

Note that a part of a heater wire connected to the heater 31 is provided around the thermistor 32, and the core metal around the thermistor 32 is heated by this heater wire. Furthermore, since the length of the heater wire around the thermistor is shorter than that of the heater wire constituting the heater 31, the amount of heat generated per unit area is the same as that of the heater 31, but the total amount of heat generated is smaller. Temperature rise will be slower.

The control unit 20 includes a diode D, a step-down converter 21, a pull-up resistor Rpu, a heater control device (for example, a heater control section 22), and a heater drive circuit 23. Step-down converter 21 is supplied with power from battery 10 via diode D. Diode D is a backflow prevention element. Step-down converter 21 steps down battery voltage Vbat supplied from battery 10 to generate internal power supply voltage PWRi.

One end of the pull-up resistor Rpu is connected to the output terminal of the step-down converter 21, and the other end is connected to the ground wiring via the thermistor 32. Further, a wiring branching from the wiring connecting the pull-up resistor Rpu and the thermistor 32 is connected to the heater control section 22 . Through this branch wiring, a voltage corresponding to the temperature detected by the thermistor 32 is input to the heater control section 22 .

The heater control section 22 operates based on the internal power supply voltage PWRi. The heater control section 22 is, for example, a microcontroller unit (MCU) that includes a calculation section capable of executing a program, a timer, an AD converter, a PWM signal generation circuit, and the like. The heater control unit 22 controls the power supplied to the heater so that the detected temperature value obtained from the thermistor 32 approaches the temperature set value. At this time, the heater control unit 22 generates a PWM signal for driving the heater drive circuit 23 using the feedback signal FB generated in the heater drive circuit 23 in addition to the temperature detection value obtained from the thermistor 32 . The details of the function of this heater control section 22 will be described later.

The heater drive circuit 23 controls the power supplied to the heater 31 based on the PWM signal output by the heater control section 22. The heater drive circuit 23 includes a switching transistor 24 and a resistor Rfb. In the switching transistor 24, the PWM signal is input to the gate, the source is connected to the ground wiring via the resistor Rfb, and the battery voltage Vbat supplied from the battery 10 is applied to the drain. The switching transistor 24 outputs a feedback signal FB from its source to the heater control unit 22 and supplies power to the heater 31 . Note that although the resistor Rfb and the feedback signal FB are clearly shown in FIG. 1, a configuration that does not use these configurations is also possible.

Here, control of the heater by the heater system 1 according to the first embodiment will be briefly described. Therefore, FIG. 3 shows a graph illustrating the difference in temperature control results depending on the presence or absence of target temperature correction processing in the heater system according to the first embodiment.

In the heater system 1 according to the first embodiment, the heater 31 is controlled so that the detected temperature value detected by the thermistor 32 approaches the target temperature, but the heated object heated by the heater 31 and the part where the thermistor 32 is installed are separated from each other. Therefore, if the heater is controlled while keeping the target temperature constant, the skin temperature of the ring portion 41, which is the object to be heated, will deviate from the target temperature. The upper diagram of FIG. 3 shows the temperature control results when the target temperature is kept constant without performing the target temperature correction process. As shown in the upper diagram of FIG. 3, in this case, the temperature of the thermistor 32 rises later than the skin temperature of the ring part 41, so the skin temperature of the ring part 41 is higher than the target temperature, and the deviation increases over time. becomes larger.

On the other hand, the lower diagram of FIG. 3 shows the result of temperature control when the target temperature correction process is performed in the heater system 1 according to the first embodiment. As shown in the lower diagram of FIG. 3, in the heater system 1 according to the first embodiment, the initial target temperature at the beginning of heating is set higher than the original target temperature, and after the temperature value detected by the thermistor 32 reaches the initial target temperature, Target temperature correction processing is performed to gradually lower the target temperature. As a result, in the heater system 1 according to the first embodiment, the temperature value detected by the thermistor 32 is quickly brought closer to the actual target temperature value, and the temperature control accuracy by the heater 31 is improved. This temperature correction process will be explained below.

In the heater system 1 according to the first embodiment, the heater control unit 22 performs target temperature correction processing. Therefore, the heater control section 22 will be explained in detail below. The heater control unit 22 sets, as the temperature setting value, an initial target temperature setting value indicating a temperature higher than a target temperature setting value indicating the temperature in a heated state of the heated object (for example, the core metal of the ring part 41), Power is supplied to the heater 31 until the detected temperature value reaches the initial target temperature setting value. Then, after the detected temperature value reaches the initial target temperature set value, the heater control unit 22 supplies power to the heater 31 while decreasing the temperature set value so that the temperature detected as the detected temperature value decreases over time. After the temperature set value matches the target temperature set value, power is supplied to the heater 31 according to the target temperature set value.

The configuration of the heater control section 22 that performs the above operation will be explained. Therefore, FIG. 4 shows a block diagram of the heater control section 22 of the heater system according to the first embodiment. Although FIG. 4 describes an example in which the heater control unit 22 is configured by hardware, the functions can also be realized by software. Furthermore, in the example shown in FIG. 4, a heater drive circuit 23, a heater 31, and a thermistor 32 are shown in order to explain the functions of the heater control section 22 according to the first embodiment.

As shown in FIG. 4, the heater control section 22 includes a temperature set value generation processing section 51, a temperature detection processing section 52, and a drive signal generation section 53. The temperature set value generation processing unit 51 generates a temperature set value Tset based on the information stored in the register, and outputs it to the drive signal generation unit 53. The temperature detection processing section 52 converts a voltage value obtained from a change in the resistance value of the thermistor 32 into a digital value and outputs a detected temperature value Tdet. The drive signal generation unit 53 outputs a PWM signal whose duty ratio changes based on the difference between the temperature set value Tset and the detected temperature value Tdet to the heater drive circuit 23 that controls the power supplied to the heater 31.

The temperature set value generation processing section 51 includes a target temperature register 61, a temperature correction amount register 62, an addition processing section 63, a subtraction period register 64, a timer 65, a slope register 66, and a subtraction processing section 67.

The target temperature register 61 stores a target temperature set value Ttgt. The target temperature setting value Ttgt is a temperature desired to be set as the skin temperature of the ring portion 41. In the heater system 1 according to the first embodiment, the initial target temperature set value Tini, which is the target value of the temperature set value Tset detected from the thermistor, is set to a higher temperature than the target temperature set value Ttgt at the start of heating. In the example shown in FIG. 4, the difference between the initial target temperature setting value Tini and the target temperature setting value Ttgt is stored in the temperature correction amount register 62 as the temperature correction amount Tcor. The addition processing unit 63 adds the target temperature set value Ttgt and the temperature correction amount Tcor to generate an initial target temperature set value Tini. The subtraction period register 64 stores a subtraction period setting value Tst that specifies the time during which the temperature setting value Tset is decreased from the initial target temperature setting value Tini toward the target temperature setting value Ttgt. The timer 65 starts measuring time in response to the detected temperature value Tdet reaching the initial target temperature setting value Tini. The timer 65 measures time by counting down with the subtraction period setting value Tst as the maximum value. The slope register 66 stores a slope ΔT indicating the slope when the initial target temperature setting value Tini is decreased. The subtraction processing unit 67 generates a temperature set value Tset by subtracting the initial target temperature set value Tini in accordance with the slope set value during the period in which the output value of the timer 65 indicates the time period.

Here, the slope ΔT is a value expressed by equation (1).
ΔT=Tcor/Tst... (1)
Furthermore, the temperature set value Tset can be expressed by equation (2), where t is the time that the timer 65 outputs. Note that t is a value that decreases to 0, with Tst being the maximum value.
Tset=Tini-ΔT*(Tst-t)... (2)

Note that in FIG. 4, a register for storing the initial target temperature setting value Tini may be provided, and the target temperature register 61, temperature correction amount register 62, and addition processing section 63 may be omitted. Further, the slope ΔT stored in the slope register 66 may be calculated within the heater control unit 22 using the temperature correction amount Tcor and the subtraction period setting value Tst, and stored in the slope register 66.

The setting values stored in each register will be explained with reference to FIG. 5. FIG. 5 is a diagram illustrating temperature parameters used in the heater control section 22 of the heater system 1 according to the first embodiment. As shown in FIG. 5, the target temperature set value Ttgt is the final target temperature of the skin temperature of the ring portion 41. The initial target temperature set value Tini is a value obtained by adding the temperature correction amount Tcor to the target temperature set value Ttgt. The subtraction period set value Tst is a period that starts when the detected temperature value Tdet reaches the initial target temperature set value Tini, and is started when the detected temperature value Tdet from the thermistor 32 reaches the initial target temperature set value Tini. This specifies the length of the period from when the target temperature setting value Ttgt is returned to the target temperature setting value Ttgt. Further, the slope ΔT is determined by the above equation (1).

The drive signal generation section 53 includes a comparator 71, an output adjustment processing section 72, and a PWM generation processing section 73. The comparator 71 compares the temperature set value Tset and the detected temperature value Tdet and outputs a difference value between the two values. The output adjustment processing section 72 prevents the output value of the comparator 71 from becoming smaller than zero, and converts the difference value into a target voltage of the feedback voltage indicated by the feedback signal FB. The PWM generation processing section 73 generates a PWM signal whose duty ratio changes according to the differential voltage between the output value of the output adjustment processing section 72 and the feedback voltage.

From the above description, the heater system 1 according to the first embodiment sets the initial target temperature set value Tini, which is the target value of the detected temperature value Tdet obtained from the thermistor 32 at the time of starting heating, to be lower than the final target temperature set value Ttgt. Set it high. In the heater system 1 according to the first embodiment, after the detected temperature value Tdet reaches the initial target temperature set value Tini, the temperature set value Tset is reduced to the target temperature set value by taking the time indicated by the subtraction period set value Tst. Gradually lower to Ttgt. As a result, in the heater system 1 according to the first embodiment, even if the thermistor 32 is placed at a position away from the ring part 41 that is the target of heating control, it is possible to improve the accuracy of temperature control of the ring part 41. Can be done. The temperature correction process of the heater system 1 quickly increases the temperature of the core metal of the spoke parts 43 around the thermistor 32, so that the temperature of the core metal of the ring part 41 and the temperature of the core metal of the spoke parts 43 can be adjusted. This is because the difference in can be reduced.

Furthermore, in the heater system 1 according to the first embodiment, by performing the temperature correction process, the temperature of the ring portion 41 can be stabilized at the target temperature at an early stage.

Embodiment 2
In the second embodiment, a modification of the heater system 1 according to the first embodiment will be described. In a heater system, if control is performed using the same target temperature set value Ttgt regardless of the temperature of the heating object before heating, there is a problem that the final temperature of the heating object will vary widely. Therefore, FIG. 6 shows a graph illustrating the difference in temperature control results due to the difference in temperature before the start of temperature rise of the steering wheel.

As shown in Figure 6, in control using the same target temperature set value Ttgt, if the temperature of the atmosphere around the steering wheel before heating varies by about -20°C to +20°C, the final temperature control The results vary by about ±2.5°C. Therefore, in the heater control unit 22a according to the second embodiment, the value of the control parameter is corrected based on the detected temperature value Tdet before heating, and the heater is controlled based on the corrected control parameter. Therefore, FIG. 7 shows a block diagram of the heater control section 22a according to the second embodiment.

As shown in FIG. 7, the heater control section 22a according to the second embodiment is the heater control section 22 in which a parameter correction section 81 is added. The parameter correction unit 81 calculates a correction value for the control parameter based on the value of the detected temperature value Tdet detected at the start of operation, and provides the corrected control parameter to the temperature set value generation processing unit 51 and the drive signal generation unit 53. . Specifically, the parameter correction unit 81 sets a first control parameter group corresponding to a predetermined first temperature on the low temperature side and a second control parameter group corresponding to a predetermined second temperature on the high temperature side. A control parameter group is held, and a correction value of the control parameter is calculated based on the ratio of the temperature difference between the first temperature and the second temperature and the first detected temperature value Tdet.

Here, the control parameter group includes a target temperature set value Ttgt, parameters for PID control of the PWM generation processing unit 73 (for example, control gain, time, etc.), parameters for temperature compensation control (for example, subtraction period set value Tst, temperature correction amount Tcor, etc.).

Next, the operation of the heater system according to the second embodiment including this heater control section 22a will be explained. FIG. 8 shows a flowchart explaining the operation of the heater system according to the second embodiment. As shown in FIG. 8, when the heater system according to the second embodiment starts operating, it first performs an initialization process to initialize the hardware and software (step S1).

Subsequently, the heater control unit 22a determines whether the current processing cycle is the first heater control routine (step S2). If it is determined in step S2 that this is the first heater control routine (YES branch of step S2), the parameter correction unit 81 acquires the thermistor temperature (for example, detected temperature value Tdet) from the thermistor 32 (step S3 ). Then, the parameter correction unit 81 determines whether or not the obtained detected temperature value Tdet is lower than the first temperature (for example, −20° C.) (step S4). In this step S4, if it is determined that the detected temperature value Tdet is lower than the first temperature, a control parameter group corresponding to the first temperature is set as a control parameter group by the temperature set value generation processing unit 51 and the drive signal generation unit. 53 (step S5).

On the other hand, if it is determined in step S4 that the detected temperature value Tdet is higher than or equal to the first temperature, it is determined whether the detected temperature value Tdet is higher than the second temperature (for example, +20° C.) (step S6 ). In this step S6, if it is determined that the detected temperature value Tdet is equal to or higher than the second temperature, a control parameter group corresponding to the second temperature is set as a control parameter group by the temperature setting value generation processing unit 51 and the drive signal generation unit. 53 (step S7). On the other hand, if it is determined in step S6 that the detected temperature value Tdet is lower than the second temperature, the control parameter group calculated by linear interpolation is set as the control parameter group by the temperature set value generation processing unit 51 and the drive signal generation unit 53. (step S8). Note that details of the control parameter group calculated by linear interpolation in step S8 will be described later.

When the setting of the control parameter group in steps S5, S7, and S8 is completed, the heater control section 22a performs main processing of heater control using the temperature set value generation processing section 51, the temperature detection processing section 52, and the drive signal generation section 53. (Step S9). Then, in response to the completion of the main processing, communication processing is performed to transmit the control state to the host system (step S10), and the determination processing of step S2 is performed again. In the determination process of step S2, if it is determined that this is not the first heater control routine (NO branch of step S2), the heater control unit 22a does not perform the setting process of the control parameter group in steps S3 to S8. The main process of step S9 is executed.

Here, correction of the control parameter group by linear interpolation in step S8 will be explained. Therefore, FIG. 9 shows a diagram illustrating a parameter correction method in the heater system according to the second embodiment. In the example shown in FIG. 9, Tmin corresponds to the first temperature, Tmax corresponds to the second temperature, Pmin corresponds to the first control parameter group, and Pmax corresponds to the second control parameter group. . Then, the parameter correction unit 81 calculates corrected control parameters by linear interpolation processing for each of the parameters included in the control parameter group.

The parameter correction unit 81 uses the first control parameter group when the first detected temperature value Tdet is smaller than the first temperature Tmin, and uses the second control parameter group when it is smaller than the second temperature Tmax. Use a group of control parameters. Further, when the first detected temperature value Tdet is a temperature temp between the first temperature Tmin and the second temperature Tmax, the parameter correction unit 81 adjusts the first temperature Tmin and the second temperature Tdet. A correction value for the control parameter is calculated based on the ratio between the temperature difference from Tmax and the temperature temp which is the first detected temperature value. This corrected control parameter Ptemp is calculated based on equation (3).
Ptemp=(temp-Tmin)×(Pmax+Pmin)/(Tmax-Tmin)+Pmin... (3)

The temperature control result when using the corrected control parameters calculated using the parameter correction unit 81 in this way will be described. FIG. 10 shows a graph illustrating the temperature control results depending on the difference in temperature before the start of temperature increase in the heater system according to the second embodiment. As shown in Figure 10, by correcting the control parameters, even if there is a temperature difference of about ±20°C in the heating target before heating starts, the final temperature variation can be suppressed to about ±1.0°C. Can be done.

From the above description, by using the heater system according to the second embodiment, even if there is variation in the temperature of the object to be heated before starting heating, the final temperature variation can be suppressed.

Embodiment 3
In the second embodiment, for example, it is assumed that the target temperature set value Ttgt corresponding to the second temperature Tmax is lower than the initial target temperature set value Tini, but the target temperature set value Ttgt is lower than the initial target temperature set value Tini. The temperature may be higher than that.

In this way, when the target temperature set value Ttgt is higher than the initial target temperature set value Tini, the subtraction period set value Tst in Embodiments 1 and 2 is set as the temperature set value calculation period, and the initial target temperature is set during this temperature set value calculation period. Addition processing is performed to increase the temperature set value starting from the temperature set value Tini so that it approaches the target temperature set value Ttgt. That is, when the target temperature set value Ttgt is higher than the initial target temperature set value Tini, the subtraction processing section 67 needs to be used as an addition processing section. Furthermore, by making the subtraction processing section 67 an arithmetic section that can perform addition and subtraction, the first and second embodiments can be used regardless of the magnitude relationship between the target temperature set value Ttgt and the initial target temperature set value Tini. Similar control can be achieved.

From the above description, in the third embodiment, the process when the target temperature setting value Ttgt is higher than the initial target temperature setting value Tini has been described. That is, even in such a case, by using the subtraction processing section 67 as an arithmetic section capable of addition processing, it is possible to realize the same processing as the control described in the first and second embodiments.

Note that the present invention is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit. The present invention can be used in a heating device in which a member to be heated and a temperature detection element are located at separate locations, and its application is not limited to the above-mentioned steering wheel. For example, in addition to vehicle heating devices such as car seats, armrests, and interior panels, it can be used in a variety of applications, such as home heating equipment, industrial heating equipment, various snow removal and ice removal equipment, anti-fog equipment, heating cooking equipment, etc. Can be done.

1 Heater system 10 Battery 20 Control unit 21 Step-down converter 22 Heater control section 23 Heater drive circuit 24 Switching transistor 31 Heater 32 Thermistor 41 Ring section 42 Boss section 43 Spoke section 51 Temperature set value generation processing section 52 Temperature detection processing section 53 Drive signal Generation section 61 Target temperature register 62 Temperature correction amount register 63 Addition processing section 64 Subtraction period register 65 Timer 66 Slope register 67 Subtraction processing section 71 Comparator 72 Output adjustment processing section 73 PWM generation processing section 81 Parameter correction section Rfb Resistor Rpu Pull-up Resistance FB Feedback signal Sup_PWR Heater power Tdet Detected temperature value Tset Temperature set value Ttgt Target temperature set value Tcor Temperature correction amount Tini Initial target temperature set value ΔT Slope Tst Subtraction period set value

Claims (9)

heater and
a temperature detection element attached to a member to be heated to which the heater is attached, at a position different from the member directly heated by the heater;
a heater control unit that controls power given to the heater so that the detected temperature value obtained from the temperature detection element approaches the temperature set value,
The heater control section includes:
setting an initial target temperature setting value indicating a temperature higher than a target temperature setting value indicating a temperature in a heated state of the heated object as the temperature setting value;
supplying power to the heater until the detected temperature value reaches the initial target temperature set value;
Supplying power to the heater while decreasing the temperature set value so that the temperature detected as the detected temperature value decreases with time after the detected temperature value reaches the initial target temperature set value,
A heater system that supplies power to the heater according to the target temperature setpoint after the temperature setpoint matches the target temperature setpoint. The heater control section includes:
a temperature set value generation processing unit that outputs the temperature set value;
a PWM generation processing unit that outputs a PWM signal whose duty ratio changes based on the difference between the temperature setting value and the detected temperature value to a heater drive circuit that controls power supplied to the heater;
The heater system according to claim 1, comprising: The temperature set value generation processing section includes:
a target temperature register that stores the target temperature set value;
a temperature correction amount register that stores a temperature correction amount that is a difference between the target temperature setting value and the initial target temperature setting value;
an addition processing unit that adds the temperature correction amount to the target temperature set value to generate the initial target temperature set value;
a timer that starts measuring time in response to the detected temperature value reaching the initial target temperature set value;
a subtraction period register that stores a subtraction period setting value that specifies a time period measured by the timer;
a slope register that stores a slope setting value indicating a slope of subtraction of the temperature setting value during the timing period;
a subtraction processing unit that generates the temperature set value by subtracting the initial target temperature set value according to the slope set value during a period in which the output value of the timer indicates the time period;
The heater system according to claim 2, comprising: The heater control section includes:
4. The method according to claim 1, further comprising a parameter correction section that corrects various control parameters within preset ranges based on the first detected temperature value measured at the first time after the start of operation among the detected temperature values. Heating system as described. The parameter correction unit includes a first control parameter group corresponding to a predetermined first temperature on the low temperature side, and a second control parameter group corresponding to a predetermined second temperature on the high temperature side; 5. The heater system according to claim 4, wherein the correction value of the control parameter is calculated based on a ratio between a temperature difference between the first temperature and the second temperature and the first detected temperature value. The heater is wound around a ring part of an automobile steering wheel,
The heater system according to claim 1, wherein the temperature detection element is attached to a boss portion that connects the ring portion to a steering column, or a spoke portion that connects the boss portion and the ring portion. A heater drive circuit that supplies power to the heater is configured such that the temperature difference between the target temperature of the heater and the detected temperature value obtained by the temperature detection element that detects the temperature of the heated object heated by the heater becomes zero. A heater control device that outputs a control signal,
a target temperature register that stores a target temperature set value corresponding to the target temperature;
a temperature correction amount register that stores a temperature correction amount for the target temperature set value;
a subtraction period register that stores a subtraction period setting value indicating a length of time for applying the corrected temperature setting value as the target temperature in place of the target temperature setting value;
a temperature set value generation processing unit that outputs the target temperature based on the set values stored in the target temperature register, the temperature correction amount register, and the subtraction period register;
a drive signal generation section that outputs a PWM signal whose duty ratio changes according to the magnitude of the difference between the detected temperature value and the target temperature to the heater drive section; the temperature set value generation processing section;
outputting the initial target temperature set value as the target temperature until the detected temperature value reaches an initial target temperature set value obtained by adding the temperature correction amount to the target temperature set value;
After the detected temperature value reaches the initial target temperature set value, a value obtained by gradually subtracting the initial target temperature set value over a period corresponding to the subtraction period set value to the target temperature set value is set to the target temperature set value. Heater control device that outputs temperature. A heater drive circuit that supplies power to the heater is configured such that the temperature difference between the target temperature of the heater and the detected temperature value obtained by the temperature detection element that detects the temperature of the heated object heated by the heater becomes zero. A heater control program executed in a semiconductor device that outputs a control signal,
The semiconductor device includes:
a target temperature register that stores a target temperature set value corresponding to the target temperature;
a temperature correction amount register that stores a temperature correction amount for the target temperature set value;
a subtraction period register that stores a subtraction period setting value indicating the length of time for applying the corrected temperature setting value as the target temperature in place of the target temperature setting value;
The heater control program includes:
outputting the initial target temperature set value as the target temperature until the detected temperature value reaches an initial target temperature set value obtained by adding the temperature correction amount to the target temperature set value;
After the detected temperature value reaches the initial target temperature set value, a value obtained by gradually subtracting the initial target temperature set value over a period corresponding to the subtraction period set value to the target temperature set value is set to the target temperature set value. Output as temperature,
A heater control program that outputs a PWM signal whose duty ratio changes according to the magnitude of the difference between the detected temperature value and the target temperature to the heater drive unit. heater and
a temperature detection element attached to a member to be heated to which the heater is attached, at a position different from the member directly heated by the heater;
a heater control unit that controls power given to the heater so that the detected temperature value obtained from the temperature detection element approaches the temperature set value,
The heater control section includes:
setting an initial target temperature setting value indicating a temperature higher than a target temperature setting value indicating a temperature in a heated state of the heated object as the temperature setting value;
supplying power to the heater until the detected temperature value reaches the initial target temperature set value;
After the detected temperature value reaches the initial target temperature set value, power is supplied to the heater while changing the temperature set value so that the temperature detected as the detected temperature value approaches the target temperature set value. death,
A heater system that supplies power to the heater according to the target temperature setpoint after the temperature setpoint matches the target temperature setpoint.

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