JPH07208259A - Vehicle-mounted load control device - Google Patents

Abstract

PURPOSE:To dispense with a resistor for detecting the current, and reduce the cost by providing a battery voltage detecting means to detect the voltage of a vehicle-mounted battery, and detecting the abnormality of the vehicle- mounted load based on the fluctuation range of the battery voltage before and after the switching of charging/non-charging to the vehicle-mounted load. CONSTITUTION:A switch load control means 40 of a microcomputer 22 controls a heater 19 for heating the catalyst as the vehicle-mounted load in the catalyst for purifying the exhaust emission, and a starter control means 41 controls a starter switch 28 to switch the charging/non-charging of a starter motor 27. A voltage detecting means 42 to detect and store the voltage of a battery 26 is provided. The fluctuation range of the battery voltage before and after the switching to the charging and non-charging to the heater 19 for heating the catalyst by switching a relay 17 and the starter switch 28 and the starter motor 27 is measured by a measuring means 43. The abnormality of the vehicle- mounted load is judged by an abnormality judging means 44 according to the voltage fluctuation range by this measuring means 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle engine exhaust gas purification device, and more particularly, the present invention relates to an on-vehicle load control device for detecting abnormality such as disconnection of a heating heater provided on a catalyst.

[0002]

2. Description of the Related Art In recent years, strict exhaust gas regulations have been demanded by vehicles, and early heating of the catalyst has brought about great effects. As a technique in such a field, Japanese Patent Laid-Open No. 4-18
The technique disclosed in Japanese Patent No. 3920 has been developed.
This document describes a technique in which a heating heater is provided on a three-way catalyst to activate the catalyst early in order to improve the purification efficiency at the time of cold starting in an exhaust purification system of an engine. In order to achieve early heating of the catalyst, a catalyst heating heater having a larger current capacity than ever is required. By the way, if the catalyst heater is operating normally,
The exhaust gas purification rate can be improved at the time of starting or immediately after starting. However, when an abnormality such as an open or a short occurs in the heater for heating the catalyst, the purifying action cannot be expected properly until the catalyst is activated by exhaust heat. Therefore, it is desired to detect an abnormality of the heater for heating the catalyst and surely replace the defective one in the repair shop. Along with this, a large current detection circuit has been indispensable for detecting abnormality of the catalyst heating heater. The large current detection circuit will be described in detail below.

FIG. 11 is a diagram showing a conventional heater current detection circuit for heating a catalyst. As shown in the figure, the battery voltage 101, the driving transistor 103, the heater 10
2 are connected. A resistor 106 for converting a current into a voltage is inserted in the current path of the heater 102. The voltage proportional to the current generated in the resistor 106 is amplified by the inverting amplifier including the operational amplifier 105, the feedback resistor 108, the DC voltage power source 104, and the voltage dividing resistors 109 and 110.
The amplified signal is converted to an A / D converter (Analog to Digital Converte
r) Captured by 111 and converted into a digital signal.

[0004]

By the way, in the above large current detection circuit, the electric power generated in the resistor 106 is the voltage V
And the current I. Here, the voltage V needs to be, for example, about 500 mV in order to guarantee the detection accuracy. If the current I is 5 A, the heat generation amount of the resistance is about 2.5 w, but if it is 30 A, the heat generation amount is 15 w, and a low resistance and large resistance of 500 mV / 30 A = 0.16 Ω is obtained. Will be needed. Therefore, there is a problem in that the electronic control unit is extremely disadvantageous in terms of mounting on a printed circuit board and the cost of the electronic control unit. Further, it is conceivable to simply provide a temperature sensor in the catalyst instead of detecting the electric current, but the cost will of course increase.

Therefore, in view of the above problems and problems, the present invention can detect an abnormality of an on-vehicle load such as a heater for heating a catalyst, reliably detect a large current, and can be achieved at an inexpensive cost. The purpose is to provide.

[0006]

In order to solve the above problems, the present invention provides a vehicle-mounted load control device having the following configuration. An in-vehicle battery, an in-vehicle load that is connected to the in-vehicle battery and operates by receiving electric power from the in-vehicle battery, a switch that switches between on-vehicle load and on-vehicle battery energization / de-energization, and a switch control circuit that controls the switch The in-vehicle load control device is provided with a battery voltage detecting means for detecting the voltage of the in-vehicle battery.

A measuring means is provided for measuring a fluctuation range of the battery voltage before and after switching between energization and de-energization of the load by switching the switch based on the battery voltage detected by the detecting means. Further, an abnormality determining means for determining an abnormality of the vehicle-mounted load based on the voltage fluctuation range by the measuring means is provided.

[0008]

According to the on-vehicle load control device of the present invention, by providing the battery voltage detecting means for detecting the voltage of the on-vehicle battery, the on-vehicle battery of the on-vehicle battery can be realized without using the current detecting resistor as in the conventional case. By detecting the voltage, an abnormality is detected when no current flows to the heater for heating the catalyst.
For this reason, the current detection circuit is not required, and the cost can be reduced. The battery voltage detected by the detection means is used to measure the fluctuation range of the battery voltage before and after switching between energization and de-energization of the load by switching the switch, and the abnormality of the vehicle-mounted load is determined from the voltage fluctuation range. The abnormality of the heater for heating the catalyst is detected, and the heater having the abnormality can be reliably replaced at the repair shop.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an overall configuration according to an embodiment of the present invention. As shown in the figure, an air flow meter 1, a throttle opening sensor 2, an idle switch 3, a fuel injection injector 15 and the like are attached to an intake system of a vehicle. The exhaust system is provided with an oxygen sensor 7, a catalyst 18 for purifying exhaust gas, a heater 19 for heating the catalyst as a vehicle-mounted load, a relay 17 as a switch for controlling the heater, etc. therein.

The control unit 20 includes inputs S1, S2, S3 from an air flow meter 1, a throttle opening sensor 2, an idle switch 3, engine speed (Ne, G) sensors 4, 5, a water temperature sensor 6, and an oxygen sensor 7. S
Based on 4, S5, S6, and S7, energization S15 to the injector 15, energization S16 to the igniter 16, and energization S17 to the relay 17 are controlled. The catalyst 18 is capable of redox treatment in a stoichiometric atmosphere, and the control unit 20 adjusts the fuel injection amount and the like based on the signal from the oxygen sensor 7 and the like so that this state is always maintained.

FIG. 2 is a diagram showing the internal structure of the control unit 20 shown in FIG. As shown in the figure, in the control unit 20, the inputs of the signals S1 to S7 are processed by the input circuit 21 and transferred to the microcomputer 22. The microcomputer 22 processes the input signal in accordance with the program, and always outputs the optimum injection amount and ignition timing through the output circuit 23 to the energization S15, 16, 1 described above.
7 is output. A power supply 24 is connected to the input circuit 21, the microcomputer 22, and the output circuit 23.
The battery voltage of the battery 26 is supplied to the power supply 24 via the ignition key 25.

FIG. 3 is a diagram showing functional blocks controlled by the microcomputer 22 shown in FIG. As shown in the figure, the switch load control means 40 as a switch control circuit of the microcomputer 22 controls a load such as the catalyst heating heater 19. Starter control means 4
Reference numeral 1 controls a starter switch 28 that switches between energization / de-energization of the starter motor 27. That is, when the driver turns on a starter driving switch (not shown), the microcomputer 22 detects this and outputs a signal to the starter switch 28 to drive the starter motor 27. The voltage detection means 42 detects and stores the voltage of the battery 26. The measuring means 43 uses the battery voltage detected by the detecting means 42 to detect the relay 17 and the starter switch 2.
The fluctuation range of the battery voltage before and after switching between energization and non-energization of the catalyst heating heater 19 and the starter motor 27 by switching 8 is measured. Abnormality judgment means 4
Reference numeral 4 determines an abnormality of the vehicle-mounted load based on the voltage fluctuation range by the measuring means 43. First, the operation of the load 19 which is a catalyst heating heater by the load control means 40 will be described.

FIG. 4 is a flow chart showing an example of the operation of the catalyst heating heater 19 of FIG. This routine is executed, for example, every 64 ms. As shown in the figure, in step P1, it is determined whether the ignition (IG) key 25 is within 5 seconds after being turned on. If the above determination is "YES" in Step P2, it is determined whether the water temperature is 60 ° or less.

In step P3, the above judgment is "YE
If “S”, it is determined whether the battery voltage is 11V or higher. If the above determination is "YES" in Step P4, it is determined whether or not 30 seconds or more have passed since the previous energization. If the above determination is "YES" in Step P5, the catalyst heating heater 19 is energized.

At step P6, if any of the above judgments is "NO", the catalyst heating heater 19
It is not energized by the relay 17. The time from the previous energization is stored in step P4 because the control unit 20 is reset when the ignition key 25 is repeatedly turned on and off. That is, this is to prevent the catalyst heater 19 from being heated by being energized each time the ignition key 25 is turned on. Next, load 19 which is a heater for heating the catalyst
A circuit for operating the will be described.

FIG. 5 is a diagram showing a circuit for storing the time since the previous energization. The catalyst heating heater 19 shown in this figure is not provided with a resistance for current detection as shown in the conventional circuit of FIG. That is, the present invention detects the voltage of the on-vehicle battery as will be described later without using a current detecting resistor, and detects an abnormality when no current flows to the catalyst heating heater 19. Therefore, unlike the conventional case, the current detection circuit is unnecessary, and the cost can be reduced. However, a circuit for storing the time from the previous energization is provided as follows. As shown in the figure, the energizing signal from the microcomputer 22 drives the transistor 35 for the pre-driver. By this driving, the transistor 38 is turned on, so that the heater 19 for heating the catalyst is energized. Resistance 3 at the same time as the energizing signal
Capacitor 34 is charged via 3. here,
Specifically, the resistance value of the resistor 33 is 1 kΩ and the capacitor 34 is
If the capacitance of the capacitor is 33 μF and the resistance value of the resistor 32 is 910 kΩ, the capacitor 34 will be discharged 30 seconds after the end of energization
Voltage drops to about 1.6V. The charge of the capacitor 34 is maintained regardless of the presence or absence of the power supply of the control unit 20, and after the ignition key 25 is turned on, if the voltage of the capacitor 34 is 1.6 V or more, a sufficient time has passed from the previous energization. It is judged that the time has not passed and the power is not supplied. This information is the A / D of the input circuit 21.
It is given to the load control device 40 via a converter 30 (Analog to Digital Converter).

By the above control, the catalyst is heated by the catalyst heating heater 19 before the engine is started, and the exhaust gas purification function is exhibited immediately after the engine is started. Although it is possible that the starter switch is turned on while the catalyst heating heater 19 is energized, deterioration of exhaust gas, battery overcurrent, and the like may occur.
Until the heating of 9 is completed, the starter control means 41 prohibits energization of the starter. Next, the battery voltage detecting means 42 and the measuring means 43 will be described.

FIG. 6 is a flow chart showing a battery voltage detection routine, and FIG. 7 is a timing chart showing changes in the battery voltage due to the operation of the ignition key and the starter. The routine shown in FIG. 6 is, for example, 6
It is performed every 4 ms. In Step P10, it is determined whether the catalyst heating heater 19 is energized. Figure 7
As shown in (a) and (b), the ignition key 25
When the heater is turned ON, the heater 19 for heating the catalyst is turned on at the same time.
Energization in the N state is in progress.

In step P11, the above judgment is "Y
If it is energized at "ES", the battery voltage changes as shown in FIG. 7D, and the battery voltage VHON at the time of change is stored in the memory of the voltage detecting means 42. Finally, the battery voltage immediately before the catalyst heating heater 19 is turned off is stored. In step P12, if the catalyst heating heater 19 is not energized, it is checked whether it is the first time after the catalyst heating heater 19 is turned off. If it is the second time or more, subsequent steps P13, 14
Skip.

In step P13, the above step P
If it is the first time in 12, then the battery voltage VHOFF at that time
(See FIG. 6D) is stored in the memory of the voltage detecting means 42. In Step P14, the measuring means 43 calculates ΔVH = VHOFF−VHON (FIG. 7 (d)).
reference). That is, ΔVH is 0 when the catalyst heating heater 19 is
It is a value indicating the difference in battery voltage when the power supply is turned off after the power supply becomes N. When the catalyst heating heater 19 is cold, a rush current flows according to the temperature. Therefore, by measuring the voltage difference immediately before and after the catalyst heating heater 19 is turned off, accurate measurement can be performed. It is also important for accurate measurement to prevent other loads from being turned ON and OFF at the same time when measuring VHON and VHOFF.

In step P15, as shown in FIG. 7C, it is determined whether the starter is in the ON operation. As described above, the starter controller 41 controls the starter switch 28 from the ON state to the OF state.
Only after the F state is reached, the ON operation is prohibited and the energization of the starter motor is prohibited. Step P16
In, if the above determination is "YES", it is determined whether the following inequality holds for the engine speed Ne. The engine speed Ne becomes as shown in FIG. 7 (d) when the starter is turned on.

400 rpm ≦ Ne ≦ 500 rpm In step P17, if the above inequality is satisfied, the battery voltage VSON is stored in the memory. Figure 7
As shown in (d), the engine speed Ne is 500 rp.
The battery voltage at m will be stored. If the inequality is not satisfied in step P16, the process of this step is skipped.

At step P18, the starter is turned on.
It is judged whether it is the first time after the FF operation. If it is the second time or more, the subsequent steps P19 and 20 are skipped. If the above determination is "YES" in Step P19, the battery voltage VSOFF (see FIG. 7D) is stored in the memory. In Step P20, the measuring means 43 causes Δ
The calculation of VS = VSOFF-VSON is performed (see FIG. 7D). From this calculation, it is possible to turn the starter ON
The difference in battery voltage during FF operation is obtained. However, in order to equalize the load conditions of the starter as much as possible, step P
Compare engine speed at 16, 400-500 rp
The battery voltage is taken in only when it is between m. Next, the abnormality determining means 44 will be described. FIGS. 8, 9 and 10 are flowcharts showing the first, second and third examples of the abnormality determination routine of the heater 19 for heating the catalyst.

As shown in FIG. 8, in step P30, it is first determined whether or not the loading of .DELTA.VH and .DELTA.VS has been completed. Furthermore, it is determined that the abnormality / normality determination has not been performed even once after the ignition key 25 is turned on. If this determination is "NO", the following step processing is not performed. In Step P31, the above determination is “YE
If “S”, then it is determined whether the following inequality holds. That is, it is determined whether .DELTA.VS is within the normal range.

1V≤ΔVS≤8V If not within this normal range, the following step processing is not performed. If ΔVS is less than 1V, it is considered that there is an abnormality such as a disconnection in the current path of the starter. When the voltage exceeds 8 V, it is considered that the battery capacity has decreased. Therefore, the abnormality determination is not performed.

In step P32, it is determined whether the following inequalities hold. ΔVH ≤0.5V In step P33, if the above determination is "YES",
It is considered that the catalyst heating heater 19 is abnormal on the disconnection side. If the determination in step P32 is "NO" in step P34, it is determined whether the following inequalities hold.

ΔVH ≧ 6V In step P35, if the above judgment is “NO”,
A normal determination is made within 0.5V ≦ ΔVH ≦ 6V. If the above determination is "YES" in Step P36, it is determined that the catalyst heating heater 19 is abnormal. In other words, it is considered to be an abnormality on the overcurrent (short) side.

Next, in FIG. 9, in step P40, it is first determined whether or not the loading of .DELTA.VH and .DELTA.VS has been completed. Furthermore, it is determined that the abnormality / normality determination has not been performed even once after the ignition key 25 is turned on. If this determination is "NO", the following step processing is not performed. In Step P41, the above determination is “YE.
If “S”, then it is determined whether the following inequality holds. That is, it is determined whether .DELTA.VS is within the normal range.

1V≤ΔVS≤8V If not within this normal range, the following step processing is not performed. If ΔVS is less than 1V, it is considered that there is an abnormality such as a disconnection in the current path of the starter. Further, when the voltage exceeds 8 V, it is considered that the capacity of the battery has decreased. Therefore, the abnormality determination is not performed.

In step P42, it is determined whether the following inequalities hold. (ΔVH / ΔVS) × 100 ≦ 1% In step P43, if the above determination is “YES”,
It is considered that the catalyst heating heater 19 is abnormal on the disconnection side. If the determination in step P42 is "NO" in step P44, it is determined whether the following inequalities hold.

(ΔVH / ΔVS) × 100 ≧ 100% In step P45, if the above determination is “NO”, the catalyst heating heater 19 is determined to be normal. Step P4
If the above determination is "YES" in 6, the catalyst heating heater 19 is determined to be abnormal. In other words, it is regarded as an abnormality on the overcurrent (short circuit) side.

In FIG. 10, steps P42 and P44 are different from FIG. In FIG. 8, ΔV
The determination was performed using the absolute value of H, but in FIG.
The determination is made by taking the ratio with ΔHS. As a result, the battery capacity can be corrected, and the accuracy of determination can be increased. Next, in FIG. 10, in step P50, it is first determined whether or not the loading of .DELTA.VH and .DELTA.VS is completed. Furthermore, it is determined that the abnormality / normality determination has not been performed even once after the ignition key 25 is turned on. If this determination is "NO", the following step processing is not performed.

In step P51, the above judgment is "Y.
If "ES", it is determined whether the following inequality is satisfied. That is, it is determined whether .DELTA.VS is within the normal range. 1V≤ΔVS≤8V If not within this normal range, the following step processing is not performed. If ΔVS is less than 1V, it is considered that there is an abnormality such as a disconnection in the current path of the starter. When the voltage exceeds 8 V, it is considered that the battery capacity has decreased. Therefore, the abnormality determination is not performed.

In step P52, it is determined whether the following inequalities hold. a = (current ΔVH / previous ΔVH) / (current ΔVS
/ Previous ΔVS) ≦ 0.7 In step P53, if the above determination is “YES”,
It is considered that the catalyst heating heater 19 is abnormal on the disconnection side.

In Step P54, Step P42
If the determination is “NO”, it is determined whether the following inequalities hold. a ≧ 1.5 In step P55, if the above determination is “NO”, the catalyst heating heater 19 is determined to be normal.

In step P56, the above judgment is "Y.
If "ES", the catalyst heating heater 19 is determined to be abnormal. In other words, it is regarded as an abnormality on the overcurrent (short circuit) side. Note that steps P52 and P55 in FIG. 10 are different from those in FIGS. ΔVS and ΔV at the last start
The value of H is stored, and ΔVS, ΔVH at the time of this start
The ratio is calculated as described above from the value of. This is to prevent an erroneous determination caused by making a determination with only one measurement value by taking a ratio with the previous time.

If a battery dedicated to driving the heater 19 for heating the catalyst can be provided, it is possible to make a more accurate determination because it is not affected by other loads. In that case, the import in FIG. 6 and step P30 in FIG.
It is not necessary to perform the determination in the determination end step P31 of .DELTA.VS in the above. By doing this,
It is possible to further prevent erroneous determination due to disturbance. Also,
The methods of FIGS. 7, 8 and 9 may be used in an appropriate combination.

Although the embodiment has been described above with respect to the abnormality detection of the catalyst heating heater 19, a large current load, for example, a steering wheel heating heater, a seat (seat) heater, an air conditioning heater, an oxygen sensor heater, an electric steering, Of course, it can be applied to an electric winch.

[0039]

As described above, according to the present invention, the battery voltage detecting means for detecting the voltage of the on-vehicle battery is provided, and based on the fluctuation range of the battery voltage before and after switching the on / off of the on-vehicle load. Since the abnormality of the vehicle-mounted load is detected, the resistor for current detection is not required, and there is an excellent effect on the cost of mounting the electronic control unit.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of a control unit 20 of FIG.

FIG. 3 is a diagram showing functional blocks that a microcomputer 22 of FIG. 22 controls.

4 is a flowchart showing an example of the operation of the catalyst heating heater 19 of FIG.

FIG. 5 is a diagram showing a circuit for storing a time since the last energization.

FIG. 6 is a flowchart showing a battery detection routine.

FIG. 7 is a timing chart showing changes in battery voltage due to operations of an ignition key and a starter.

FIG. 8 is a diagram showing a first example of an abnormality determination routine for the catalyst heating heater 19;

FIG. 9 is a diagram showing a second example of an abnormality determination routine for the catalyst heating heater 19.

FIG. 10 is a diagram showing a third example of an abnormality determination routine for the catalyst heating heater 19.

FIG. 11 is a diagram showing a conventional catalyst heater current detection circuit.

[Explanation of symbols]

 17 ... Relay 19 ... In-vehicle load (heater for heating catalyst) 22 ... Microcomputer 26 ... In-vehicle battery 28 ... Starter switch 40 ... Switch control unit 41 ... Starter control means 42 ... Voltage detection means 43 ... Measurement means 44 ... Abnormality determination means

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 16, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

In step P15, as shown in FIG. 7C, it is determined whether the starter is in the ON operation. As described above, the starter controller 41 controls the starter switch 28 from the ON state to the OF state.
Only after the F state is reached, the ON operation is prohibited and the energization of the starter motor is prohibited. Step P16
In, if the above determination is "YES", it is determined whether the following inequality holds for the engine speed Ne. The engine speed Ne becomes as shown in FIG. 7 ( e ) when the starter is turned on.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

400 rpm ≦ Ne ≦ 500 rpm In step P17, if the above inequality is satisfied, the battery voltage VSON is stored in the memory. Figure 7
As shown in (d) and (e) , the engine speed Ne is 5
The battery voltage at 00 rpm will be stored. If the inequality is not satisfied in step P16, the process of this step is skipped.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

[0032] In FIG. 9, differs from the FIG. 8 is a step P42 and 44. In FIG. 8, ΔVH
Although the determination was made using the absolute value of, in FIG.
The determination is made by taking the ratio with HS. As a result, the battery capacity can be corrected, and the accuracy of determination can be increased.
Next, in FIG. 10, in step P50, first,
It is determined whether the loading of ΔVH and ΔVS is completed. Furthermore, it is determined that the abnormality / normality determination has not been performed even once after the ignition key 25 is turned on. If this determination is "NO", the following step processing is not performed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

In step P56, the above judgment is "Y.
If "ES", the catalyst heating heater 19 is determined to be abnormal. In other words, it is regarded as an abnormality on the overcurrent (short circuit) side. In FIG. 10, steps P52 and 54 is different from FIG. 8 and 9. ΔVS and ΔV at the last start
The value of H is stored, and ΔVS, ΔVH at the time of this start
The ratio is calculated as described above from the value of. This is to prevent an erroneous determination caused by making a determination with only one measurement value by taking a ratio with the previous time.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

If a battery dedicated to driving the heater 19 for heating the catalyst can be provided, it is possible to make a more accurate determination because it is not affected by other loads. In that case, the import in FIG. 6 and step P30 in FIG.
It is not necessary to perform the determination in the determination end step P31 of .DELTA.VS in the above. By doing this,
It is possible to further prevent erroneous determination due to disturbance. Also,
The methods of FIGS. 8 , 9 , and 10 may be used in an appropriate combination.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing an internal configuration of a control unit 20 of FIG.

3 is a diagram showing functional blocks that a microcomputer 22 of FIG. 2 controls.

4 is a flowchart showing an example of the operation of the catalyst heating heater 19 of FIG.

FIG. 5 is a diagram showing a circuit for storing a time since the last energization.

FIG. 6 is a flowchart showing a battery detection routine.

FIG. 7 is a timing chart showing changes in battery voltage due to operations of an ignition key and a starter.

FIG. 8 is a diagram showing a first example of an abnormality determination routine for the catalyst heating heater 19;

FIG. 9 is a diagram showing a second example of an abnormality determination routine for the catalyst heating heater 19.

FIG. 10 is a diagram showing a third example of an abnormality determination routine for the catalyst heating heater 19.

FIG. 11 is a diagram showing a conventional catalyst heater current detection circuit.

[Explanation of Codes] 17 ... Relay 19 ... In-vehicle load (heater for heating catalyst) 22 ... Microcomputer 26 ... in-vehicle battery 28 ... starter switch 40 ... switch control section 41 ... starter control means 42 ... voltage detection means 43 ... measuring means 44 ... Abnormality judgment means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01M 15/00 Z

Claims (9)

[Claims] 1. An in-vehicle battery, an in-vehicle load that is connected to the in-vehicle battery and operates by receiving power supply from the in-vehicle battery, a switch that switches between energization / de-energization of the in-vehicle load and the in-vehicle battery, and controls the switch. In a vehicle-mounted load control device having a switch control circuit for operating the vehicle, a battery voltage detection unit that detects the voltage of the vehicle-mounted battery; An in-vehicle load control device comprising: a measuring unit that measures a fluctuation range of the battery voltage before and after switching the energization; and an abnormality judging unit that judges an abnormality of the in-vehicle load based on the voltage fluctuation range by the measuring unit. . 2. The in-vehicle load control device according to claim 1, wherein the in-vehicle load is a heater. 3. The vehicle-mounted load control device according to claim 1, wherein the vehicle-mounted load is a motor. 4. The in-vehicle load control device according to claim 2, wherein the heater is a catalyst heating heater. 5. The switch is an ignition key, and the switch control circuit prohibits energization by a starter when the vehicle-mounted load is energized by the ignition key. The in-vehicle load control device described in 1. 6. The measuring means measures a fluctuation range of a battery voltage before and after switching between energization / de-energization of a catalyst heating heater which is the vehicle-mounted load, and energization / de-energization of a starter motor after the switching. The fluctuation range of the battery voltage before and after switching is switched, and the abnormality determination means switches the fluctuation range of the battery voltage before and after switching between energization / de-energization of the catalyst heating heater and energization / de-energization of the starter motor. The vehicle-mounted load control device according to claim 1, wherein an abnormality of the heater for heating the catalyst is determined based on a fluctuation range of front and rear battery voltages. 7. The abnormality determining means includes a fluctuation range of a battery voltage before and after switching energization / de-energization to the catalyst heating heater and a fluctuation range of a battery voltage before and after switching energization / de-energization to the starter motor. Characterizing that the abnormality of the heater for heating the catalyst is determined based on the ratio of
The in-vehicle load control device according to claim 6. 8. The abnormality determining means switches the current width and the previous time of the fluctuation range of the battery voltage before and after switching between energization / de-energization of the catalyst heating heater and energization / de-energization of the starter motor. 7. The vehicle-mounted system according to claim 6, wherein the ratio of the fluctuation range of the battery voltage before and after the current time and the previous time is taken, and the abnormality of the heater for heating the catalyst is determined based on the ratio between the former and the latter. Load control device. 9. The vehicle-mounted load control device according to claim 2, wherein a dedicated battery is provided for the heater.