JP2000258385A - Heat control device of air/fuel ratio sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the heat control device of an air/fuel ratio sensor for reducing a period where a combustion state becomes unstable due to the use of a heavy fuel. SOLUTION: When the cancellation of a door lock is detected (step 100), the start of preheating is permitted (step 104) and it is judged whether fuel used for an internal engine is a heavy fuel or not (step 106). When fuel used for the internal engine is a nonheavy fuel, a target temperature Tc is set to T2 (step 110). When the fuel used for the internal engine is a heavy fuel, the target temperature Tc is set to T1 that is higher than T2 (step 108). Then, the amount of conduction to the heater is controlled so that the sensor temperature T can reach the target temperature T1. As this result, when the heavy fuel is in used, the sensor temperature T reaches an activation temperature faster and the air/fuel ratio feedback control is started readily.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heater control device for an air-fuel ratio sensor, and more particularly to a heater control device for an air-fuel ratio sensor having a function of preheating the air-fuel ratio sensor before starting the internal combustion engine.

[0002]

2. Description of the Related Art In an internal combustion engine, air-fuel ratio feedback control for controlling the air-fuel ratio toward a stoichiometric air-fuel ratio is performed by correcting the fuel injection amount based on the air-fuel ratio of an exhaust passage. By performing the air-fuel ratio feedback control, it is possible to obtain an effect that the purification performance of the exhaust gas by the catalytic converter is maintained at a high level, and the deterioration of the fuel efficiency is prevented. In order to realize such air-fuel ratio feedback control, an air-fuel ratio sensor for detecting the air-fuel ratio is provided in the exhaust passage. Generally, the air-fuel ratio sensor has a characteristic of outputting a signal corresponding to the oxygen concentration in an activated state heated to an activation temperature of several hundred degrees or more. For this reason, the air-fuel ratio sensor has a built-in heater for heating to the activation temperature. After energization of the heater of the air-fuel ratio sensor is started, a certain period of time is required until the sensor temperature reaches the activation temperature, that is, until the air-fuel ratio feedback control based on the output signal of the air-fuel ratio sensor becomes possible. Needed. Therefore,
Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 5-202785, preheating for starting energization of a heater is performed before the start of the internal combustion engine so that the air-fuel ratio feedback control can be started immediately after the start of the internal combustion engine. An air-fuel ratio control device is known. In this air-fuel ratio control device, when the opening of the vehicle door is detected, the start of the internal combustion engine is predicted, and the preheating of the heater of the air-fuel ratio sensor is started.

[0003]

Incidentally, the properties of the fuel of the internal combustion engine may be changed depending on the season. That is, light fuel that evaporates easily in winter when the temperature is low is used, and heavy fuel that hardly evaporates is used in the summer when the temperature is high. When heavy fuel is used as the fuel for the internal combustion engine, the fuel injected from the fuel injection valve does not vaporize sufficiently compared to when light fuel is used, and the amount of fuel supplied to the combustion chamber is reduced. Decrease. Therefore, the air-fuel ratio becomes lean, and the combustion state becomes unstable.

[0004] In the above-mentioned conventional example, the start of the internal combustion engine is predicted when the opening of the vehicle door is detected irrespective of the property of the fuel of the internal combustion engine, and the preheating of the heater of the air-fuel ratio sensor is started. For this reason, if heavy fuel is used in the conventional example, the air-fuel ratio becomes lean until the air-fuel ratio feedback control becomes possible, and the combustion state becomes unstable. In this case, drivability is reduced, emission of exhaust gas is increased, and fuel efficiency is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a heater control device for an air-fuel ratio sensor that shortens the period in which the combustion state becomes unstable due to the use of heavy fuel. I do.

[0006]

The above object is achieved by the present invention.
As described in the paragraph, in the heater control device of the air-fuel ratio sensor having a pre-heating means for energizing the heater provided in the air-fuel ratio sensor provided in the internal combustion engine before starting the engine, whether the fuel is heavy fuel A fuel discriminating means for discriminating whether or not the fuel is heavy fuel, and a power control means for increasing a power supplied to the heater by the preheating means as compared with a case where the fuel is not heavy fuel. This is achieved by the heater control device of the air-fuel ratio sensor.

According to the first aspect of the present invention, the preheating means starts energizing the heater before starting the engine,
Prior to starting the engine, the air-fuel ratio sensor is heated to a temperature corresponding to the amount of electricity supplied to the heater. When the temperature of the air-fuel ratio sensor becomes equal to or higher than the activation temperature, the air-fuel ratio feedback control based on the output signal of the air-fuel ratio sensor becomes possible. According to the present invention, when the fuel used in the internal combustion engine is a heavy fuel, the amount of electricity supplied to the heater is increased as compared with the case where the fuel is a non-heavy fuel. As a result, when heavy fuel is used, the temperature of the air-fuel ratio sensor rises more quickly. Therefore, the air-fuel ratio sensor reaches the activation temperature earlier, and the air-fuel ratio feedback control based on the output signal of the air-fuel ratio sensor is started earlier. Therefore,
According to the present invention, the period during which the combustion state becomes unstable due to the use of heavy fuel is shortened.

[0008]

FIG. 1 is a system configuration diagram of an internal combustion engine to which a heater control device for an air-fuel ratio sensor according to an embodiment of the present invention is applied. The internal combustion engine of the present embodiment is controlled by an electronic control unit (hereinafter, referred to as ECU) 10. As shown in FIG. 1, the internal combustion engine includes a cylinder block 1
2 is provided. Inside the cylinder block 12, a cylinder 14 and a water jacket 16 are formed. The water jacket 16 is provided with a water temperature sensor 18. The water temperature sensor 18 outputs a signal corresponding to the temperature of the cooling water flowing inside the water jacket 16 (hereinafter, referred to as water temperature THW) to the ECU 10. E
The CU 10 determines the water temperature T based on the output signal of the water temperature sensor 18.
HW is detected.

A piston 20 is provided inside the cylinder 14. The piston 20 can slide inside the cylinder 14 in the vertical direction in FIG. A cylinder head 22 is fixed to an upper portion of the cylinder block 12. An intake port 24 and an exhaust port 26 are formed in the cylinder head 22. The bottom surface of the cylinder head 22, the top surface of the piston 20, and the side wall of the cylinder 14 define a combustion chamber 28. The above-described intake port 24 and exhaust port 26 both open to the combustion chamber 28. The combustion chamber 28 has a spark plug 30
The tip of is exposed. The ignition plug 30 ignites fuel in the combustion chamber 28 by receiving an ignition signal from the ECU 10.

The internal combustion engine also has an intake valve 34 and an exhaust valve 36. Intake port 24 and exhaust port 26
A valve seat for the intake valve 34 and the exhaust valve 36 is formed at the opening to the combustion chamber 28, respectively. Intake valve 3
4 and the exhaust valve 36 are separated from and seated on each valve seat,
The intake port 24 and the exhaust port 26 are opened and closed, respectively.

The intake port 24 has an intake manifold 3
8 are in communication. A fuel injection valve 40 is provided in the intake manifold 38. The fuel injection valve 40 is ECU1
Fuel is injected into the intake manifold 38 according to a command signal given from zero. A surge tank 42 communicates with the upstream side of the intake manifold 38. An intake pipe 44 communicates further upstream of the surge tank 42. The intake pipe 44 is provided with a throttle valve 46. In the vicinity of the throttle valve 46, a throttle opening sensor 48 is provided.

An air flow meter 50 communicates upstream of the intake pipe 44. The air flow meter 50 outputs a signal corresponding to the flow rate of the air passing therethrough to the ECU 10. The ECU 10 detects the intake air amount GA of the internal combustion engine based on the output signal of the air flow meter 50. An air cleaner 51 communicates further upstream of the air flow meter 50. The outside air filtered by the air cleaner 51 flows into the intake pipe 44.

On the other hand, an exhaust passage 52 communicates with the exhaust port 26 of the internal combustion engine. A catalytic converter 54 is provided in the exhaust passage 52. Catalytic converter 54
Purifies the exhaust gas by reacting hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) contained in the exhaust gas. Air-fuel ratio sensors 56 and 58 are provided on the upstream and downstream sides of the catalytic converter 54, respectively.
Are arranged. In the present embodiment, the air-fuel ratio sensor 56,
Although the configuration of 58 is the same, it may be different.

The internal combustion engine also has a rotation speed sensor 60. The rotation speed sensor 60 outputs a pulse signal to the ECU 10 every time the internal combustion engine rotates by a predetermined crank angle. The ECU 10 detects the engine speed NE of the internal combustion engine based on the output signal of the engine speed sensor 60. EC
The door lock sensor 62 is connected to U10.
The door lock sensor 62 outputs a signal according to the locked state of the vehicle door. The ECU 10 controls the door lock sensor 6
The locked state of the vehicle door is detected based on the output signal of (2).

FIG. 2 shows an internal configuration of the air-fuel ratio sensors 56 and 58 together with a connection circuit with the ECU 10. As shown in FIG. 2, the air-fuel ratio sensors 56 and 58 have a sensor element 66 therein made of a material such as zirconia.
And a heater 68 for heating the sensor element 66. One terminal of the sensor element 66 is a constant voltage source 70
The other terminal is connected to the ECU 10 and grounded via a resistor 72. In this state, the current flowing through the sensor element 66 (hereinafter, referred to as sensor current I) is such that the temperature of the sensor element 66 (hereinafter, referred to as sensor temperature T) is a predetermined activation temperature Te (for example, 65).
When the temperature is between 0 ° C. and 700 ° C. or more, the pressure varies according to the oxygen concentration in the exhaust passage 52 shown in FIG. A voltage corresponding to the sensor current I is input to the ECU 10, and the oxygen concentration in the exhaust gas, that is, the air-fuel ratio is detected based on the input voltage.

On the other hand, the heater 68 is connected to the ECU 10 via a power supply control circuit 74. Energization control circuit 74
Performs duty control of a current supplied to the heater 68 using the vehicle-mounted battery 75 as a power supply in accordance with a control signal supplied from the ECU 10. A heater voltage detection circuit 76 and a heater current detection circuit 78 are connected to the heater 68. The heater voltage detection circuit 76 outputs a signal corresponding to the voltage applied to the heater 68 to the ECU 10. The heater current detection circuit 78 outputs a signal corresponding to the current flowing through the heater 68 to the ECU 10.
The ECU 10 detects a resistance value of the heater 68 (hereinafter, referred to as a heater resistance R) based on these signals.

The ECU 10 calculates a target temperature T as described later.
c is set, and the amount of electricity supplied to the heater 68 is controlled so that the sensor temperature T becomes the target temperature Tc. Note that the heater resistance R
Changes according to the temperature of the heater 68. So, ECU
Reference numeral 10 determines the temperature of the heater 68 based on the heater resistance R, and uses this heater temperature as the sensor temperature T. As described above, when the sensor temperature T is maintained at or above the activation temperature Te, the sensor current I changes according to the air-fuel ratio. Therefore, the ECU 10 can detect the air-fuel ratio based on the sensor current I by controlling the amount of current supplied to the heater 68 as described above. Then, the ECU 10 executes air-fuel ratio feedback control for performing feedback control of the fuel injection amount based on the detected air-fuel ratio.

In the air-fuel ratio feedback control, when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, the fuel injection amount is reduced, and when the air-fuel ratio is leaner, the fuel injection amount is increased. The fuel ratio is maintained within a predetermined range near the stoichiometric air-fuel ratio. When the air-fuel ratio is near the stoichiometric air-fuel ratio, the above-described catalytic converter 60 exhibits high purification performance for exhaust gas. Therefore, by executing the air-fuel ratio feedback control, the HC and C in the exhaust gas are controlled.
O and NOx can be effectively removed by the catalytic converter 54. Further, according to the air-fuel ratio feedback control, the air-fuel ratio does not become excessively rich or lean, so that it is possible to prevent both deterioration of the fuel efficiency and instability of the combustion state.

During a cold start of the internal combustion engine, the sensor temperature T
Has almost dropped to the outside air temperature, so that it takes some time for the sensor temperature T to be heated to the activation temperature Te. In the present embodiment, in order to enable the execution of the air-fuel ratio feedback control immediately after the start of the internal combustion engine, when the engine start is predicted (for example, when the unlocking of the vehicle door is detected), the target temperature Tc is set, and energization of the heaters 68 of the air-fuel ratio sensors 56 and 58 is started before the engine is started so that the sensor temperature T becomes the target temperature Tc. Hereinafter, the heater 68 performed before the engine is started.
The energization to is referred to as preheating.

Incidentally, the properties of the fuel of the internal combustion engine may be changed according to the season. That is, light fuel that evaporates easily in winter when the temperature is low is used, and heavy fuel that hardly evaporates is used in the summer when the temperature is high. When heavy fuel is used as the fuel for the internal combustion engine, the fuel injected from the fuel injection valve 40 does not vaporize sufficiently compared to when a non-heavy fuel such as light fuel is used during a cold period. ,
The amount of fuel supplied to the combustion chamber 28 decreases. Therefore, the air-fuel ratio becomes lean, and the combustion state becomes unstable. In this case, drivability is reduced, emission of exhaust gas is increased, and fuel efficiency is deteriorated.

Therefore, the present embodiment sets the target temperature Tc higher when heavy fuel is used as the fuel for the internal combustion engine than when non-heavy fuel is used,
The sensor temperature T is set to be higher than the activation temperature Te earlier. As a result, the air-fuel ratio feedback control can be performed early, and the period during which the fuel state becomes unstable is shortened.

Hereinafter, a routine executed by the ECU 10 at the time of preheating will be described in detail. FIG. 3 is a flowchart illustrating a routine executed by ECU 10 to determine target temperature Tc in preheating. FIG.
Is a periodic interruption routine started at a predetermined time interval, for example. When the routine shown in FIG. 3 is started, first, the process of step 100 is executed.

In step 100, the door lock sensor 6
Based on the output signal of No. 2, it is determined whether or not the door lock of the vehicle is being unlocked and whether or not there is a history of unlocking the door within a predetermined time. As a result, when the door lock is in the closed state and there is no history of the door lock being released within the predetermined time, in the following step 102, the preheat permission flag F1 is set to “0”,
Preheat start is prohibited. In this case, the pre-heat is not performed, and the current routine ends. On the other hand, if it is determined in step 100 that the door lock is being unlocked, or if there is a history that the door lock has been unlocked within a predetermined time, in step 104, the preheat permission flag F1 is set to “1”, and Start is allowed. Then, the process of step 106 is executed. The preheat permission flag F1 is "0".
Is assumed to have been initialized to

In step 106, it is determined whether or not the fuel used for the internal combustion engine is heavy fuel. This determination is performed based on the set value of the fuel determination flag F2. The fuel determination flag F2 is set, for example, at the time of the previous start of the internal combustion engine according to a routine shown in FIG. If the fuel discrimination flag F2 is set to "1" in step 106, it is determined that heavy fuel is being used for the internal combustion engine, and then the process of step 108 is executed. On the other hand, when the fuel determination flag F2 is set to “0” in step 106, it is determined that non-heavy fuel is used for the internal combustion engine.
Step 110 is executed.

In step 108, the target temperature Tc is set to T1.
Is set to Then, the current routine ends.
In step 110, the target temperature Tc is set to T2 (<T1). Then, the current routine ends. FIG. 4 is a flowchart of a routine executed by the ECU 10 to set the fuel determination flag F2 when the internal combustion engine is started. The routine shown in FIG. 4 is a periodic interruption routine started at predetermined time intervals.

When the routine shown in FIG. 4 is started, first, the processing of step 200 is executed. Step 20
At 0, it is determined whether the elapsed time T after the start of the internal combustion engine is less than a predetermined value d. If T <d is satisfied in step 200, the process of step 202 is executed next. On the other hand, in step 200, T <d
Is not satisfied, the process of step 204 is executed next.

In step 202, it is determined whether or not the water temperature THW is lower than a predetermined value e. If THW <e is satisfied in step 202, it is determined that the internal combustion engine has not yet been warmed up.
Is performed. On the other hand, in step 202,
If THW <e is not satisfied, then the process of step 204 is executed.

In step 206, it is determined whether or not the engine speed NE is less than a predetermined value f. As a result, NE
When <f is satisfied, it is determined that the combustion of the internal combustion engine is unstable and heavy fuel is used in the internal combustion engine. Then, the process of step 208 is executed. On the other hand, if NE <f is not satisfied in step 206, it is determined that the combustion state is stable, and that the non-heavy fuel is used in the internal combustion engine.
4 is executed.

In step 204, the fuel discriminating flag F2
Is set to “0”. Then, the current routine ends. In step 208, the fuel discrimination flag F2 is set to "1". Then, the current routine ends. As described above, according to the routine shown in FIG. 4, when the elapsed time T after the start of the internal combustion engine is less than d and the water temperature THW is less than e, the engine speed NE is less than the predetermined value f. It is determined that heavy fuel is being used.

When the routine shown in FIG. 3 is completed, the routine shown in FIG. 5 is subsequently started. FIG. 5 shows the case where the sensor temperature T is set to the target temperature Tc determined by the routine shown in FIG.
9 is a flowchart of a routine that is executed by the ECU 10 at the time of preheating to be performed. When the routine shown in FIG. 5 is started, first, the process of step 300 is executed.

In step 300, it is determined whether or not execution of preheating is permitted. This determination is made based on the state of the preheat permission flag F1. In step 300, when the preheat permission flag F1 is set to "0", it is determined that the execution of the preheat is not permitted, and then the process of step 302 is performed. On the other hand, when the preheat permission flag F1 is set to “1”, it is determined that the execution of the preheat is permitted, and then the process of step 304 is performed.

In step 302, the air-fuel ratio sensor 56
Duty ratio H in energization control to heater 68 at 58
When Tduty is set to “0”, energization of the heater 68 is stopped. When the processing of step 302 is completed,
This routine is ended. In step 304, the current sensor temperature T is detected based on the heater resistance R.
Then, next, the process of step 306 is executed.

In step 306, the sensor temperature T is set as shown in FIG.
It is determined whether the temperature exceeds the target temperature Tc determined in the routine. As a result, if T> Tc is satisfied, then the process of step 308 is executed. on the other hand,
If T> Tc is not satisfied in step 306, then the process of step 310 is executed. Step 30
In step 8, the duty ratio HTduty is reduced by a predetermined value α, so that the amount of power to the heater 68 is reduced. Then, the current routine ends.

In step 310, the duty ratio HTdu
By increasing ty by the predetermined value α, the amount of electricity to the heater 68 is increased. Then, the current routine ends. In steps 308 and 310, the heater 68
By appropriately increasing or decreasing the amount of power to the sensor, the sensor temperature T
Converges to the target temperature Tc. FIG. 6 is a graph showing a change in the sensor temperature T of the air-fuel ratio sensors 56 and 58 provided in the present embodiment.

As described above, in this embodiment, when the heavy fuel is used in the internal combustion engine, the target temperature T1 is set higher than when the non-heavy fuel is used, and the heater is used. 68 is provided with a larger amount of current. As a result, the sensor temperature T rises faster when using heavy fuel than when using non-heavy fuel. Specifically, as shown in FIG. 6, during the preheating period until the engine starts at time t0, the sensor temperature T when using non-heavy fuel increases to T2. When the non-heavy fuel is used, the sensor temperature T reaches the activation temperature Te at time t2 after the engine is started, and the air-fuel ratio feedback control is started. On the other hand, the sensor temperature T when using heavy fuel rises to T1, which is higher than T2 during the preheating period. After the engine is started, the sensor temperature T reaches the activation temperature Te at a time t1 earlier than when non-heavy fuel is used, and the air-fuel ratio feedback control is started.

As described above, when the heavy fuel is used, the higher target temperature Tc is set, and the start of the air-fuel ratio feedback control is advanced, so that the period in which the combustion state generated by using the heavy fuel is unstable is increased. It is shortened. Therefore, improvement in drivability when heavy fuel is used in the internal combustion engine, reduction of emissions in exhaust gas, and
Improvements in fuel efficiency and the like are realized.

Further, according to this embodiment, when the possibility that the combustion state becomes unstable is small, that is, when a non-heavy fuel is used in the internal combustion engine, the target temperature T2 lower than T1 is set. It is set and the heater 6 is higher than when heavy fuel is used.
8 is reduced. As described above, in the present embodiment, it is prevented that an unnecessarily large electric power is supplied to the heater 68. Therefore, the heater 68
In addition, the capacity of the battery 75 that supplies power to the battery 75 can be reduced, the life of the battery 75 can be extended, and fuel efficiency can be improved by saving power.

In this embodiment, the preheating is started when the unlocking of the door of the vehicle is detected. However, the present invention is not limited to this, and other operations (for example, opening the door of the vehicle, inserting an ignition key, etc.). ) May be configured to start the preheating by the detection of ()). The determination as to whether or not the fuel is heavy fuel is not limited to the engine speed NE detected by the speed sensor 60, but may be performed based on the specific gravity of the fuel, the pressure of the vapor gas, or the like.

In the above embodiment, the temperature of the heater 68 is obtained based on the heater resistance R, and this temperature is used as the sensor temperature T. However, the method of obtaining the sensor temperature T is not limited to this. . For example, the sensor element 66 has a characteristic that the impedance decreases as the sensor temperature T increases. For this reason, the sensor element 6
Alternatively, the sensor temperature T may be determined by applying an AC voltage having a predetermined frequency to the sensor 6 and measuring the impedance of the sensor element 66 from the relationship between the applied voltage and the current. Further, while the internal combustion engine is stopped, the oxygen concentration in the exhaust passage 52 is kept constant (a value equal to the oxygen concentration at atmospheric pressure). On the other hand, the sensor current I in a situation where the oxygen concentration is kept constant increases as the sensor temperature T increases until the sensor temperature T reaches the activation temperature. Therefore,
The sensor temperature T can be determined based on the sensor current I before the engine is started.

In the above embodiment, the sensor current I continuously changes according to the air-fuel ratio.
However, the present invention is not limited to this, and instead of one or both of the air-fuel ratio sensors 56 and 58, a two-stage signal of rich / lean is output according to the air-fuel ratio. An O ₂ sensor may be used. Further, in the above embodiment, the duty amount of the power supply to the heater 68 is controlled. However, the present invention is not limited to this, and the power supply may be controlled by changing the current value linearly.

In the above embodiment, the ECU 10 executes the routine of FIG. 5 and the "preheat means" described in the claims executes the routine shown in FIG. Fuel determination means "
However, by executing the processing of steps 108 and 110 of the routine shown in FIG. 3, the "power supply amount control means" described in the claims is realized.

[0042]

As described above, according to the first aspect of the present invention,
When the fuel used in the internal combustion engine is heavy fuel, the target temperature is set high, and the amount of power to the heater is increased as compared to when the fuel is non-heavy fuel. As a result, when heavy fuel is used, the temperature of the air-fuel ratio sensor rises more quickly. Then, the air-fuel ratio sensor reaches the activation temperature earlier, and the air-fuel ratio feedback control based on the output signal of the air-fuel ratio sensor is started earlier. Therefore, according to the present invention, the period during which the combustion state becomes unstable due to the use of heavy fuel is shortened, so that the drivability is improved, the emission in the exhaust gas is reduced, and the fuel efficiency is improved. can do.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an internal combustion engine to which a heater control device for an air-fuel ratio sensor according to the present invention is applied.

FIG. 2 is a diagram showing an internal configuration of an air-fuel ratio sensor included in the system of the present embodiment, together with a connection circuit with an ECU.

FIG. 3 EC for determining a target temperature in preheating
9 is a flowchart for explaining a routine executed by U.

FIG. 4 is a flowchart of a routine executed by an ECU to set a fuel determination flag when the internal combustion engine is started.

FIG. 5 is a flowchart of a routine executed by an ECU at the time of preheating.

FIG. 6 is a graph showing a change in sensor temperature of an air-fuel ratio sensor provided in the present embodiment.

[Explanation of symbols]

 Reference Signs List 10 ECU 54 Catalytic converter 56, 58 Air-fuel ratio sensor 62 Door lock sensor 66 Sensor element 68 Heater 75 In-vehicle battery

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naohide Izumaya 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 2G004 BJ01 BL08 BL20 BM09 3G301 JA02 JA21 KA01 LC10 NA08 NB11 ND13 ND41 NE23 PA01Z PB02Z PD05A PD05Z PD13A PD13Z PE01Z PE08Z PF00Z

Claims (1)

[Claims] 1. A heater control device for an air-fuel ratio sensor having a preheating means for energizing a heater provided in an air-fuel ratio sensor provided in an internal combustion engine before starting the engine, wherein the fuel is heavy fuel. A fuel discriminating unit for discriminating whether or not the fuel is heavy fuel, and a power control unit for increasing a power supplied to the heater by the preheating means as compared with a case where the fuel is not heavy fuel. A heater control device for an air-fuel ratio sensor.