JPS63117251A - Temperature controller - Google Patents

Abstract

PURPOSE:To determine a voltage to be applied to a heating element accurately, by detecting a voltage at a connection point between the heating element and a driving means to be outputted as power source voltage during the non-driving of the driving means and as loss voltage during the driving thereof. CONSTITUTION:A heating element M1, a driving means M2 and a current detection means M3 are connected in series to a power source. A voltage detection means M4 detects a voltage at a connection point between the element M1 and the means M2 and outputs it as power source voltage during the non-driving of the means M2 and as loss voltage during the driving thereof. A control means M5 performs a feedback control of the driving and the non-driving of the means M2 so that power consumption of the element M1 determined by a voltage outputted from the means M4 and a current detected with the means M3 reaches a target power predetermined. Moreover, a power source voltage measuring means M6 and a loss voltage measuring means M7 output a command to the means M2 to make the means M2 non-driven or driven temporarily when the means M2 is driven or non-driven continuously for more than a specified time.

Description

DETAILED DESCRIPTION OF THE INVENTION Purpose of the Invention [Industrial Application Field] The present invention provides a method for activating an oxygen sensor or an air-fuel ratio sensor (oxygen concentration sensor) disposed in the exhaust system of an internal combustion engine, for example. The present invention relates to a temperature control device effective for controlling the heat generation state of a heater to a predetermined state.

[Prior Art] Conventionally, there has been a technology that uses a heater to heat an oxygen sensor or an air-fuel ratio sensor installed in the exhaust system of a vehicle internal combustion engine, for example, to control the air-fuel ratio. Are known. Here, for example, in the case of an oxygen sensor, it is necessary to maintain the temperature at 400 ['C] or higher, and in the case of an air-fuel ratio sensor, it is necessary to maintain the temperature at 600 ['C] or higher. For this purpose, the duty ratio of the heater drive signal is feedback-controlled so that the power consumption of the heater is set to a target power determined according to the operating state of the internal combustion engine at that time, and the heating state of the heater is maintained at a predetermined state. Something is being considered. As such technology, for example, "temperature control device"
(Japanese Unexamined Patent Publication No. 61-68550) etc. have been proposed.

That is, it includes a heating element, a drive switch means, a current detection means, and an extraction means for extracting a voltage at a connection point between the heat generating element and the drive switch means, which are connected in series to a power source, and when the drive switch means is turned on, the element is Operating voltage (voltage applied to drive switch means and current detection means)
On the other hand, when it is off, the power supply voltage is obtained, and the heating state of the heating element is detected from the voltage applied to the heating element obtained from the difference between the two voltages and the heater current by the current detection means, and the heating state is determined to be a predetermined state. This is a technique to adjust the on/off duty of the drive switch means so that In such conventional technology, the detection of the element operating voltage (the voltage applied to the drive switch means and the current detection means [@loss voltage]) and the power supply voltage takes a sufficiently short time compared to the heater on/off control period. This was done at regular intervals due to the execution of interval timer processing.

[Problems to be Solved by the Invention] Now, as shown in FIG. 6, the duty ratio of the heating element drive signal is between 30% (indicated by a solid line) and 70%.
% (indicated by a broken line), the voltage at the connection point between the heating element and the driving means is set to
)・Non-drive (OFF>Duty ratio control cycle (time T)
If detected at a shorter time interval (time t), the drive (O
It is possible to obtain both the loss voltage at the time of N) and the power supply voltage at the time of non-drive (OFF>).However, as shown in FIG. 6, when the duty ratio of the heating element drive signal is 90
In the case of an extremely large value such as [%], even if the voltage at the connection point is detected at every - constant time interval (time t), only the loss voltage when the heating element is driven (ON) can be detected. On the other hand, as shown in Fig. 6, when the duty ratio of the heating element drive signal is extremely small such as 10%, even if the voltage at the connection point is detected at fixed time intervals (time t), ,
Only the power supply voltage when the heating element is not driven (OFF) can be detected. In this manner, when the duty ratio of the heat generating element drive signal continues to be extremely high or extremely low, only either the loss voltage or the power supply voltage can be measured by detection at regular time intervals. Therefore, there is a problem in that the voltage applied to the heating element cannot always be accurately calculated.

Further, the relationship between the operating state of the internal combustion engine and the target power of the heating element is defined, for example, as shown in the map shown in FIG. That is, in region X of a low-load operating state (such as during idling), the exhaust gas is at a low temperature, so heating by the heating element is necessary, and the duty ratio of the heating element drive signal is approximately 100%. On the other hand, in region Y of high-load operation, the exhaust gas is at a high temperature, so there is no need for heating by the heating element, and the duty ratio of the heating element drive signal is approximately O [%]
becomes. However, as mentioned above, when the duty ratio is extremely large or extremely small, the voltage applied to the heating element cannot be detected accurately, so the consumption of the heating element decreases. There was also the problem that feedback control using electric power as a target electric power could not be accurately executed. These problems were particularly noticeable in low-load operating conditions that required extensive heating.

The present invention detects the voltage applied to the heating element and controls the power consumption of the heating element to the target power even when the duty ratio of the heating element drive signal is continuously extremely large or continuously extremely small. The purpose of the present invention is to provide a temperature control device that can be operated accurately at all times.

Structure of the Invention [Means for Solving the Problems] The present invention, which has been made to solve the above problems, as illustrated in FIG. M2 and current detection means M3, detect the voltage at the connection point of the heating element M1 and the driving means M2, and use it as a power supply voltage when the driving means M2 is not driven, and as a loss voltage when driving the driving means M2. The power consumption of the heating element M1, which is determined from the power supply voltage and loss voltage outputted by the voltage detection means M4 and the current detected by the current detection means M3, meets a predetermined target. A temperature control device comprising: a control means M5 that determines a drive signal for feedback controlling driving/non-driving of the drive means M2 so as to generate electric power; When in the driving state, it outputs a command to the driving means M2' to temporarily put the driving means M2 into a non-driving state, and
power supply voltage measuring means M for outputting a command to detect the voltage at the connection point in the non-driving state to the voltage detecting means M4;
6, when the driving means M2 is in the non-driving state continuously for a predetermined period of time or more, a command to temporarily put the driving means M2 into the driving state is output to the driving means M2, and when the driving means M2 is in the non-driving state, The gist of the present invention is a temperature control device that performs a reduction correction, comprising: loss voltage measuring means M7 that outputs a command for detecting the voltage at the connection point to the voltage detecting means M4.

The heating element M1 is, for example, a heater that generates heat in response to power supply from a power source for the purpose of activating an oxygen sensor or an air-fuel ratio sensor.

The driving means M2 can be constituted by a circuit element that switches the heating element M1 into a driving state or a non-driving state according to an external command, for example.

For example, it may be a transistor, or it may be another switching element.

The current detection means M3 detects the current flowing through the heating element M1. For example, it can be realized by a current detection resistor or the like.

The voltage detection means M4 detects the voltage at the connection point between the heating element M1 and the drive means M2, and outputs it as a power supply voltage when the drive means M2 is not driven, and as a loss voltage when the drive means M2 is driven. Here, the loss voltage is a voltage applied to the drive means M2 and the current detection means M3. For example, the voltage at the connection point is detected every predetermined period, and the driving means M
It can be configured to output as a power supply voltage or a loss voltage depending on the driving/non-driving state of No. 2.

The control means M5 determines a drive signal for controlling the drive means M2 so that the power consumption of the heating element M1, which is determined from the power supply voltage, loss voltage, and current, becomes a predetermined target power. For example, the maximum power consumption of the heating element M1 is calculated by multiplying the voltage difference between the power supply voltage and the loss voltage by the current, and the heating element M1 is driven according to the ratio between the target power determined based on the operating state of the internal combustion engine and the maximum power consumption. It can be configured to determine the duty ratio of the signal.

Further, for example, when the driving means M2 is temporarily brought into a non-driving state by the power supply voltage measuring means M6, which will be described later, the driving signal is increased by a time corresponding to the duration of the non-driving state, and on the other hand, the driving signal is increased by a period corresponding to the duration of the non-driving state. When the driving means M2 is temporarily brought into a driving state by the voltage measuring means M7, the driving signal may be corrected by decreasing the driving signal for a time corresponding to the duration of the driving state.

The power supply voltage measuring means M6 means that when the driving means M2 is continuously in a driving state for a predetermined period of time or more, the driving means M2 is temporarily put into a non-driving state and the heating element M1 and the driving means M2 are set in a non-driving state.
It outputs a command to detect the voltage at the connection point. For example, when the duty ratio of the drive signal is extremely large, the drive means M2 can be shut off and the power supply voltage can be detected.

The loss voltage measuring means M7 means that when the driving means M2 is continuously in a non-driving state for a predetermined period of time or more, the driving means M2 is temporarily driven and the voltage at the connection point between the heating element M1 and the driving means M2 is measured. It outputs a command to detect.

For example, when the duty ratio of the drive signal is extremely small, the drive means M2 can be made conductive to detect the loss voltage.

The voltage detection means M4, control means M5, power supply voltage measurement means M6, and loss voltage measurement means M7 can be realized, for example, by independent discrete logic circuits. For example, ROM, RAM, etc. including the well-known CPLI
It may also be configured as a logical operation circuit together with other peripheral circuit elements and implement the above-mentioned means according to a predetermined processing procedure.

[Function] As illustrated in FIG. 1, the temperature control device of the present invention detects the voltage at the connection point between the heating element M1 and the drive means M2, and adjusts the power supply voltage and loss voltage output by the voltage detection means M4. , the control means M5 determines a drive signal for feedback controlling the drive means M2 so that the power consumption of the heating element M1 determined from the current detected by the current detection means M3 becomes a predetermined target power. When the means M2 is continuously in the driving state for a predetermined period of time or more, the power supply voltage measuring means M6 outputs a command to the driving means M2 to temporarily put the driving means M2 into the non-driving state, and at the same time outputs a command to the driving means M2 to temporarily put the driving means M2 into the non-driving state. (A command to detect the voltage at the connection point is outputted to the voltage detection means M4, and when the drive means M2 is continuously in a non-driving state for a predetermined period of time or more, the loss voltage measurement means M71fi It outputs to the driving means M2 a command to temporarily bring the driving means M2 into a driving state, and also outputs to the voltage detecting means M4 a command to detect the voltage at the connection point in the driving state. .

In other words, when the driving means M2 is continuously in the driving state for a predetermined period of time or more, the loss voltage is detected and the power supply voltage is also detected by forcing the driving means to shift to a temporary non-driving state. When the driving means M2 is continuously in the non-driving state for a predetermined period of time or more, the power supply voltage is detected and the driving means is forcibly shifted to a temporary driving state, and the loss voltage is also detected.

Therefore, the temperature control device of the present invention can detect the power supply voltage and the loss voltage by the power supply voltage measuring means M6 and the loss voltage measuring means M7 even when any drive signal is applied to the driving means M2, and the power supply voltage and the loss voltage can be detected by the power supply voltage measuring means M6 and the loss voltage measuring means M7. Based on the detected current and the above-mentioned pressures, the power consumption of the heating element M1 is always accurately controlled to the target power. The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings. FIG. 2 shows a system configuration of a temperature control device according to a first embodiment of the present invention.

As shown in FIG. 2, the temperature control device 1 includes a heater 4 and an injector 5 that are operated by receiving power from a vehicle-mounted battery 2 via an ignition switch 3, and an electronic control device that controls the heater 4 and the injector 5. (hereinafter simply referred to as ECU). Above heater 4
is a platinum heater that is built into an oxygen sensor that is disposed in the exhaust system of an engine (not shown) and detects the concentration of residual oxygen in the exhaust gas, and that heats the oxygen sensor for the purpose of activating the oxygen sensor.

A heater drive transistor 7 and a current detection resistor 8 provided in the ECU 6 are connected to the heater 4 in series. The heater driving transistor 7 controls driving/non-driving of the heater 4 , and the current detection resistor 8 detects the current flowing through the heater 4 .

Furthermore, an injector driving transistor 9 provided in the ECtJ 6 is connected in series to the injector 5 .

The ECU 6 is configured as a logical operation circuit mainly including a CPLJ 6a, a ROM 6b, and a RAM 6C, and is connected to an input/output capotro e and an output capotro f via a common bus 6d to input and output signals. The voltage at the connection point 10 between the heater 4 and the heater drive transistor 7 and the connection point 11 between the heater drive transistor 7 and the current detection resistor 8
The voltage is input to the CPU 6a from the input/output capotro e via the multi-flex sensor 6g and the A/D converter 6h.

Further, the CPU 6a outputs a control signal to the heater driving transistor 7 and the injector driving transistor 9 via the output port f, thereby controlling the driving of the heater 4 and the injector 5.

Here, when the heater driving transistor 7 is in a non-driving state (OFF), the voltage at the connection point 1o between the heater 4 and the heater driving transistor 7 becomes the power supply voltage VH02, which is equal to the voltage of the battery 2. . On the other hand, when the heater drive transistor 7 is in the drive state (ON>), the voltage at the connection point 10 between the heater 4 and the heater drive transistor 7 is applied to the heater drive transistor 7 and the current detection resistor 8. The loss voltage VHCI becomes the loss voltage VHCI.In addition, at this time, the heater driving transistor 7
The voltage at the connection point 11 between the current detection resistor 8 and the current detection resistor 8 becomes the voltage VIH across the current detection resistor 8. Therefore, the voltage VH applied to the heater 4 can be determined from the difference between the power supply voltage VHC2 and the loss voltage VHC1, and on the other hand, the current IH flowing through the heater 4 can be determined by dividing the voltage VIH between both ends by the resistance value R1 of the current detection resistor 8. . Voltage VH applied to this heater 4
The power consumption of the heater 4 can be calculated from the current IH flowing through the heater 4.

Next, the temperature control process executed by the ECU 6 will be explained based on the flowchart shown in FIG. 3.

This temperature control process is started with the activation of the ECU 6,
It is executed repeatedly every 120 [m5ec]. First, in step 100, the heater driving transistor 7 is in the driving state (ON), and if it is determined that the front chamber is determined, the process proceeds to step 105, and if the determination is negative, the process proceeds to step 140. In step 105, which is executed when it is determined that the heater drive transistor 7 is in the drive state (ON), 1 is added to the value of the drive counter C1, and the non-drive counter C2 is reset to the value O. It is done. In the following step 110, it is determined whether the value of the drive counter C1 is 10 or more, and if it is determined that the front chamber is determined, the process proceeds to step 125, and if the determination is negative, the process proceeds to step 115.

In step 115, which is executed when the heater drive transistor 7 is in the drive state (ON) and sufficient time has not yet passed, the voltage VI across the current detection resistor 8 is
A process of A/D converting and inputting H is performed. In the following step 120, a process is performed in which the loss voltage ■HCI is A/D converted and inputted, and then the process proceeds to step 180. On the other hand, the heater driving transistor 7 is in the driving state (ON).
), which is executed when a sufficient amount of time has elapsed, in step 125, a process of resetting the drive counter C1 to the value 0 is performed. In the following step 130, the heater driving transistor 7 is temporarily brought into a non-driving state (OFF).Next, the process proceeds to step 135, where the heater driving transistor 7 is brought into a non-driving state (OFF) through the process in step 130. OFF), the power supply voltage VH
After A/D converting and inputting 02, the process proceeds to step 180.

On the other hand, in step 140, which is executed when it is determined in step 100 that the heater drive transistor 7 is not in the drive state (ON>), the drive counter C
A process is performed in which 1 is reset to the value O and 1 is added to the value of the non-drive counter C2. Next step 14
In step 5, it is determined whether the value of the non-drive counter C2 is 10 or more, and if the judgment is made that the front room is determined, the process proceeds to step 155, and if the judgment is negative, the process proceeds to step 150. In step 150, which is executed when the heater drive transistor 7 is in a non-drive state (OFF>) and sufficient time has not elapsed, a process is performed in which the power supply voltage VHC2 is A/D converted and inputted. After that, the process proceeds to step 180. Meanwhile, the heater drive transistor 7 is in the non-drive state (O
FF> and a sufficient time has elapsed, in step 155, a process of resetting the non-drive counter C2 to the value O is performed. In the following step 160, the heater drive transistor 7 is temporarily driven (ON).
Processing is performed. Next, the process proceeds to step 165, and while the heater drive transistor 7 is in the drive state (ON) due to the processing in step 160, the current detection resistor 8
A process of A/D converting and inputting the voltage VIH across 0 is performed. In the following step 170, the process of A/D converting and inputting the loss voltage VH01 is performed, and then the process proceeds to step 180. The voltage VH applied to the heater 4 is obtained by subtracting the loss voltage VHCI input in step 170.
Processing to calculate is performed. In the subsequent step 185, the current IH flowing through the heater 4 is calculated by dividing the voltage VIH inputted in step 115 or step 165 by the resistance value R1 of the current detection resistor 8. Next, proceed to step 190, and proceed to step 180 described above.
A process of calculating the maximum power consumption WIO○ of the heater 4 when the duty ratio is 100 [%] by multiplying the voltage VH applied to the heater 4 calculated in step 185 by the current IH flowing through the heater 4 calculated in step 185 above. will be carried out. In the following step 193, the fourth
Target power WM of heater 4 according to the map shown in
8 calculation processing is performed. That is, as shown in FIG. 4, in a low load state where the intake pipe pressure PM and engine speed Ne of the engine are low, the target power WM of the heater 4 is 30 [W].
It has a large value like l. On the other hand, the intake pipe pressure P
In a high load state where M and rotational speed Ne are high, the target power WM of the heater 4 is a small value such as O[-Wl. The ECU 6 stores a map as shown in Fig. 4 in advance in the ROM.
6b, and the target power WM of the heater 4 is calculated based on the map. Next, step 19
Proceed to step 6 and calculate the target power WM calculated in step 193 above.
is the maximum power consumption W100 calculated in step 190 above.
After performing processing to calculate the duty ratio DB of the drive signal output to the heater drive transistor 7 by dividing by
-Japan Temperature Control'It! Finish the process. Thereafter, this temperature control process is repeatedly executed every 120 [m5ec].

In the first embodiment, the heater 4 corresponds to the heating element M1, the heater drive transistor 7 corresponds to the drive means M2, and the current detection resistor 8 corresponds to the current detection means M3. Also, among the processes executed by the ECU 6 and the ECtJ6, (
Steps 120 and 150) serve as voltage detection means M4,
(Steps 180, 185, 190, 193, 196>
is the control means M5 (steps 100, 105, 1
10.125, 130, 135> is the power supply voltage measuring means M
6 (steps 100, 140, 145°155.
160, 170) each function as loss voltage measuring means M7.

As explained above, in the first embodiment, the duty ratio of the drive signal output to the heater drive transistor 7 is 10.
If a state close to 0 [%] continues for more than a specified time,
The heater drive transistor 7 is temporarily put in a non-drive state and the power supply voltage VHC2 is detected. On the other hand, if the duty ratio of the drive signal remains close to O [%] for a predetermined time or longer, the heater drive transistor 7 is turned off. is temporarily in a driving state to detect the loss voltage VHC1 and the voltage VH between both ends. Therefore, even when the duty ratio of the drive signal is extremely large or extremely small, the power supply voltage VHC2, loss voltage V) (CI, and both-end voltage VIH) can always be reliably detected.

Further, since the voltage applied to the heater 4 and the current flowing through the heater 4 can be calculated at all times, it is possible to accurately control the power consumption of the heater 4 to the target power WM.

In general, it is possible to perform stable temperature control of the heater 4 while minimizing the influence of changes in the resistance value of the heater 4 due to changes in the voltage of the battery 2 and temperature rises during engine operation.

In addition, when the duty ratio of the drive signal is close to 100 [%], such as when the engine is operating at low load, or when the duty ratio of the drive signal is O, such as when the engine is operating at high load.
Even if it is close to [%], the power consumption of the heater 4 can be maintained at the target power WM.

Therefore, such as during cold start or idling,
Effective control can be realized when the oxygen sensor needs to be activated by multiple heating of the heater 4.

This is particularly effective when applied to a heater for an air-fuel ratio sensor (oxygen concentration sensor) whose activation temperature is 600 ['C] or higher.

Next, a second embodiment of the present invention will be described in detail based on the drawings. The difference between this second embodiment and the previously described first embodiment is that in the second embodiment, the drive/non-drive state of the heater drive transistor is temporarily changed in order to measure the power supply voltage or loss voltage. The aim is to compensate for fluctuations in heater power consumption caused by It should be noted that since the structure of the system is the same as that of the first embodiment described above, similar parts will be denoted by the same reference numerals and explanations will be omitted.

Next, temperature control processing, which is a feature of the second embodiment, will be explained based on the flowchart shown in FIG.

This temperature control process is started with the activation of the ECU 6,
It is executed repeatedly every 120 [m5ec].

First, when the heater driving transistor 7 is in the driving state and the value of the driving counter C1 that continues counting is less than 10, the voltage across both ends V I H and the loss voltage VHC1 are A/D converted and input ( Steps 200, 205, 2
10, 215, 220).

On the other hand, when the value of the drive counter C1 is 10 or more, the drive counter C1 is reset, the previously calculated loss duty ratio DLO3S is read, and the heater drive transistor 7 is temporarily turned off to the power supply voltage. V
H02 is A/D converted and input (step 200, 2
05,210.225.230,235,240>. Next, step 250 calculates the voltage VH applied to the heater 4 from the difference between the power supply voltage VHC2 and the loss voltage VHCI.
), calculate the current IH flowing through the heater 4 by dividing the voltage VIH between both ends by the resistance value R1 of the current detection resistor 8.Step 2
55) Calculate the maximum power consumption W100 of the heater 4 (Step 260); Calculate the collected power WM of the heater 4 according to the same map as in the first embodiment described above (Step 265); The duty ratio DB of the drive signal is calculated (step 270).The output duty ratio Do is calculated by roughly adding the duty ratio DB and the loss duty ratio DLO3S (step 2
75>, when the output duty ratio Do exceeds 100 [%], the output duty ratio.

The loss duty ratio DLO8S is calculated from the difference between
is calculated, and the output duty ratio is set to 100 [%] (steps 280, 285, 290>).

After that, -Japan temperature control processing is ended. On the other hand, when the output duty ratio Do is 100 [%] or less, the loss duty ratio DLO3S80 [%] is set (steps 280, 295). After that, -Japan temperature control processing is ended.

On the other hand, when the heater driving transistor 7 is in a non-driving state and the value of the non-driving counter C2 that continues counting is less than 10, the power supply voltage VHC2 is A/D converted and inputted (steps 200 and 305). .310,315). On the other hand, when the value of the non-driving counter C2 is 10 or more, the non-driving counter C2 is reset, the previously calculated overduty ratio DOVER is read, and the heater driving transistor 7 is temporarily driven (ON) to reduce the loss. Voltage VH
CI and both-end voltage VIH are A/D converted and input (
Steps 200, 305, 310° 325, 330.3
35.340.345>. Next, step 350) calculates the voltage VH8 applied to the heater 4, step 355) calculates the current IH flowing through the heater 4, step 360) calculates the maximum power consumption wioo of the heater 4, and the first embodiment described above. The target power WM of the heater 4 is calculated according to a map similar to the above (step 365), and the duty ratio DB of the drive signal of the heater drive transistor 7 is calculated (step 370). Roughly, the over duty ratio DOVER is subtracted from the duty ratio DB to calculate the output duty ratio D○ (step 375). When the output duty ratio Do is less than O [%], the output duty ratio.

is set as the overduty ratio DOVER, and the output duty ratio is set as DO@O [%] (step 380, '38
5,390). Thereafter, the temperature control process ends.

On the other hand, when the output duty ratio D○ is O[31 or more,
Overduty comparison.

Set VER to O [%] Steps 380, 395
), then the water temperature control process ends.

Thereafter, this temperature control process is repeatedly executed every 120 [m5ec].

In the second embodiment, the heater 4 corresponds to the heating element M1, the heater drive transistor 7 corresponds to the drive means M2, and the current detection resistor 8 corresponds to the current detection means M3. Also, among the ECU 6 and the processing executed by the ECU 6, (
Steps 220 and 315) serve as voltage detection means M4,
(Steps 250, 255, 260, 265, 270,
275°280.285,290,295,350,3
55.360,365,370,375,380°38
5.390,395> is the control means M5, (step 200,205.21'0,225,235.240
> as the power supply voltage measuring means M6, step 200,
305, 310, 325, 335, and 340> each function as loss voltage measuring means M7.

As explained above, according to the second embodiment, in addition to the effects of the first embodiment described above, the following effects are achieved.

In other words, the power consumption of heater 4 is set as the target because it compensates for excess or deficiency in power consumption when heater 4' is temporarily driven or not driven for measurement of power supply voltage H02 or 11 lost voltage Vl- (C1). Feedback control of the electric power WM can be executed quickly and more accurately. This is particularly effective when applied to a heater for an air-fuel ratio sensor.

Although several embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and can be implemented in various ways without departing from the gist of the present invention. Of course.

Effects of the Invention As detailed above, according to the temperature control device of the present invention, even when the duty ratio of the heating element drive signal is continuously extremely large or extremely small, both the loss voltage and the power supply voltage are always maintained. can be detected, so the excellent effect is that the voltage applied to the heating element can be accurately determined.

In addition, with the above effect, even when the duty ratio of the heating element drive signal is extremely large or extremely small, such as when the internal combustion engine is in a low-load operating state or a high-load operating state, the power consumption of the heating element can be adjusted to the target power. It is possible to accurately perform feedback control. This is particularly effective when a large amount of heating by the heating element is required, such as during cold start or idling.

Note that, for example, the control means may increase the drive signal in response to a command to temporarily put the drive means output from the power supply voltage measurement means into a non-drive state; If the drive signal is configured to be corrected to decrease in response to a command to set the heating element to the drive state, it is possible to improve the responsiveness and followability of feedback control that uses the power consumption of the heating element as the target power, and to improve the control accuracy. It can be further improved. This is particularly effective when applied to temperature control of an air-fuel ratio sensor that requires high temperature control accuracy.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram illustrating the content of the present invention, Fig. 2 is a system configuration diagram of the first embodiment of the invention, Fig. 3 is a flowchart showing its control, and Fig. 4 is a map thereof. 5 is a flow chart showing the control of the second embodiment of the present invention, FIG. 6 is a timing chart showing the relationship between duty ratio and voltage detection time interval, and FIG. 7 is a graph showing the operating state of the internal combustion engine and the heating element. 3 is a graph showing a map that defines the relationship between power consumption and target power. Ml... Heating element M2... Drive means M3... Current detection means M4... Voltage detection means M5... Control means M6... Power supply voltage measuring means Ml... Loss voltage measuring means 1. ... Temperature control device 4 ... Heater 6 ... Electronic control device (ECtJ) 6a ... CPU 7 ... Heater driving transistor 8 ... Current detection resistor

Claims (1)

[Scope of Claims] 1. A heating element, a driving means, and a current detecting means connected in series to a power source, and detecting a voltage at a connection point between the heating element and the driving means, and determining whether the driving means is not driven. Sometimes as a power supply voltage,
On the other hand, when the driving means is driven, the power consumption of the heating element is determined from the voltage detecting means that outputs each as a loss voltage, the power supply voltage and loss voltage outputted by the voltage detecting means, and the current detected by the current detecting means. , a control means for determining a drive signal for feedback controlling driving/non-driving of the driving means so as to achieve a predetermined target power, further comprising: a temperature control device in which the driving means continues for a predetermined period of time or more; and outputs a command to temporarily put the driving means in a non-driving state to the driving means, and also outputs a command to the voltage detecting means to detect the voltage at the connection point in the non-driving state. When the power supply voltage measuring means to output and the driving means are continuously in a non-driving state for a predetermined period of time or more, a command to temporarily put the driving means into a driving state is outputted to the driving means, and the driving means A temperature control device comprising: loss voltage measuring means for outputting a command for detecting the voltage at the connection point to the voltage detecting means. 2 The control means increases the drive signal in response to a command output from the power supply voltage measurement means to temporarily put the drive means into a non-drive state, while increasing the drive signal output from the loss voltage measurement means. 2. The temperature control device according to claim 1, wherein the drive signal is corrected to decrease in response to a command to temporarily put the means into a drive state.