JPH07293295A - Exhaust temperature controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an O2 sensor from being exposed to the high temperature exhaust, by installing a means for carrying out the control so that the fuel injection quantity of a fuel injection valve is increased from the fundamental injection quantity according to the difference between the temperature of a detection part and the set temperature, when the temperature of the detection part detected by the temperature sensor becomes over a set temperature. CONSTITUTION:As for an internal combustion engine 2, a fuel injection valve 12 is installed on an intake manifold 4 in close to an intake passage 6, and an O2 sensor 14 is installed on an exhaust manifold 8 in close to an exhaust passage 10, and a spark plug 16 for the ignition combustion of the mixed gas is installed. When the temperature of a detection part for the detection by the temperature sensor 28 becomes over a set temperature, the increased injection quantity corresponding to the difference between the temperature of the detection part and the set temperature is obtained from a table by a control means 26, and the fuel in the fuel injection quantity which is obtained by adding the increased injection quantity to the fundamental injection quantity is jetted, and control is performed so that the exhaust temperature is lowered. Accordingly, the high temperature of the exhaust can be lowered to the temperature for the pertinent function of the O2 sensor 14, and the exposure to the high temperature exhaust is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas temperature control device for an internal combustion engine, and more particularly, it can prevent deterioration of an O ₂ sensor due to high temperature exhaust gas, and also an exhaust manifold and an O ₂ sensor to which the O ₂ sensor is attached. The present invention relates to an exhaust gas temperature control device for an internal combustion engine, which can also prevent deterioration of a catalyst disposed downstream of the engine.

[0002]

2. Description of the Related Art An internal combustion engine mounted on a vehicle or the like is shown in FIG.
There is one provided with a fuel injection control device as shown in FIG. Figure 9
In the figure, 302 is an internal combustion engine mounted on a vehicle or the like, and 30
Reference numeral 4 is an intake manifold, 306 is an intake passage, 308 is an exhaust manifold, and 310 is an exhaust passage. This internal combustion engine 3
02 is the intake manifold 30 by facing the intake passage 306.
4, a fuel injection valve 312 is attached, an O ₂ sensor 314 is attached to the exhaust manifold 308 facing the exhaust passage 310, and an ignition plug 316 is attached.

As shown in FIG. 10, the O ₂ sensor 314 is provided with a detector 324 having an atmosphere-side electrode 320 and an exhaust-side electrode 322 attached to the inside and outside of a solid electrolyte 318 having a cylindrical shape with a cover, respectively. The exhaust passage 31
It is facing 0. The O ₂ sensor 314 includes a detection unit 324.
An electromotive force is generated according to the ratio of the oxygen concentration of the atmosphere contacting the inside and the exhaust gas contacting the outside.

The fuel injection valve 312 and the O ₂ sensor 31
4 is connected to the control means 326 which comprises a fuel injection control device. The control means 326 uses the electromotive force corresponding to the ratio of the oxygen concentration in the exhaust gas detected by the O ₂ sensor 314 to determine that the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 302 is the target air-fuel ratio, for example, the theoretical air-fuel ratio. The fuel injection amount of the fuel injection valve 212 is controlled by feedback so as to be within the range.

As a result, the catalyst (not shown) provided in the exhaust passage 310 on the downstream side of the O ₂ sensor 314 is
The exhaust gas purification function can be effectively operated.

An example of such an O ₂ sensor is Jpn.
There are those disclosed in Japanese Patent Publication No. 2-14349 and Japanese Patent Publication No. 61-25308.

The one disclosed in Japanese Utility Model Publication No. 62-14349 is provided with a means for detecting the temperature of the detecting portion of the O ₂ sensor, and supplies secondary air for cooling to the detecting portion when the temperature of the detecting portion is high. Means are provided.

The one disclosed in Japanese Examined Patent Publication No. 61-25308 has an O ₂ sensor provided with a heater for heating,
The circuit is provided with a circuit for determining the exhaust temperature based on the operating state signal correlated with the exhaust temperature and changing the current value of the heating heater in accordance with the determination result.

[0009]

By the way, as described above, the O ₂ sensor performs feedback control of the fuel injection amount of the fuel injection valve to the basic injection amount so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio. The oxygen concentration in exhaust gas is detected.
Therefore, the O ₂ sensor is in a used state in a region where the air-fuel ratio is feedback-controlled to the target air-fuel ratio, and is not used in a region other than the region where the air-fuel ratio is controlled.

However, the area other than the control of the air-fuel ratio,
For example, the temperature of exhaust gas becomes high in a high load and high rotation speed region. Therefore, the O ₂ sensor is exposed to the exhaust gas at a temperature higher than the temperature at which it can function properly, and there is a disadvantage that deterioration is accelerated. Also, the high temperature exhaust gas is O ₂
The exhaust manifold to which the sensor is attached and the catalyst arranged on the downstream side of the O ₂ sensor also flow to the exhaust manifold and the catalyst, which causes the deterioration of the exhaust manifold and the catalyst.

[0011]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention firstly provides a fuel injection valve for injecting fuel into an intake passage of an internal combustion engine, and exhausts the exhaust gas into an exhaust passage of the internal combustion engine. An O ₂ sensor for detecting the oxygen concentration in the
A temperature sensor for detecting the temperature of the detection portion of the O ₂ sensor facing the exhaust passage is provided. When the detection portion temperature detected by the temperature sensor is lower than a set temperature, the air-fuel mixture is detected based on the oxygen concentration detected by the O ₂ sensor. While controlling the fuel injection amount of the fuel injection valve to the basic injection amount so that the air-fuel ratio of becomes the target air-fuel ratio, if the detection unit temperature detected by the temperature sensor becomes equal to or higher than the set temperature, the detection unit temperature and The control means for controlling the fuel injection amount of the fuel injection valve to increase from the basic injection amount according to the difference from the set temperature is provided.

Secondly, the present invention provides a fuel injection valve for injecting fuel into an intake passage of an internal combustion engine, and an ignition plug for igniting and burning an air-fuel mixture supplied to the internal combustion engine. the spark advance value sensor for detecting the spark advance determinants in providing, the O ₂ sensor for detecting the oxygen concentration in the exhaust gas in an exhaust passage of the internal combustion engine is provided, facing the exhaust passage of the O ₂ sensor detection A temperature sensor for detecting the temperature of the part is provided, and when the detection part temperature detected by the temperature sensor is lower than the set temperature, the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio based on the oxygen concentration detected by the O ₂ sensor. While controlling the fuel injection amount of the fuel injection valve to the basic injection amount and controlling the ignition timing of the spark plug to the basic ignition advance value based on the ignition advance value determinant detected by the ignition advance value sensor. ,Previous When the detection part temperature detected by the exhaust gas temperature sensor becomes equal to or higher than the set temperature, control is performed to increase the fuel injection amount of the fuel injection valve from the basic injection amount according to the difference between the detection part temperature and the set temperature, and The control means is provided to control the ignition timing of the spark plug to be advanced from the basic ignition advance value according to the difference between the detection unit temperature and the set temperature.

[0013]

According to the first aspect of the present invention, the exhaust gas temperature control device causes the control means to perform mixing based on the oxygen concentration detected by the O ₂ sensor when the detection part temperature detected by the temperature sensor is less than the set temperature. The fuel injection amount of the fuel injection valve is controlled to the basic injection amount so that the air-fuel ratio of the air becomes the target air-fuel ratio, and if the temperature detected by the temperature sensor exceeds the set temperature, the detected temperature and set temperature By controlling the fuel injection amount of the fuel injection valve to increase from the basic injection amount in accordance with the difference between, the fuel injection amount increased from the basic injection amount according to the difference between the detection unit temperature and the set temperature, The temperature of the exhaust gas can be lowered, the temperature of the exhaust gas can be maintained below the set temperature, and the O ₂ sensor can be prevented from being exposed to the high temperature exhaust gas.

According to the second aspect of the present invention, in the exhaust gas temperature control device, the oxygen concentration detected by the O ₂ sensor is controlled by the control means when the temperature of the detection portion detected by the temperature sensor is lower than the set temperature. Based on this, the fuel injection amount of the fuel injection valve is controlled to the basic injection amount so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio, and the ignition timing of the spark plug is adjusted based on the ignition advance value deciding factor detected by the ignition advance value sensor. The basic ignition advance value is controlled, and if the temperature detected by the exhaust temperature sensor exceeds the set temperature, the fuel injection amount of the fuel injection valve is changed according to the difference between the temperature detected and the set temperature. By controlling to increase from the basic injection amount and controlling to advance the ignition timing of the spark plug from the basic ignition advance value according to the difference between the detection part temperature and the set temperature, the detection part temperature and the set temperature To the difference Then, by the fuel injection amount increased from the basic injection amount and the ignition timing advanced from the basic ignition advance value, the temperature of the exhaust gas can be quickly reduced, and the temperature of the exhaust gas can be maintained below the set temperature, It is possible to reliably prevent the O ₂ sensor from being exposed to high temperature exhaust gas.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

1 to 4 show an embodiment of the first structure of the present invention. In FIG. 3, 2 is an internal combustion engine mounted in a vehicle or the like (not shown), 4 is an intake manifold, and 6
Is an intake passage, 8 is an exhaust manifold, and 10 is an exhaust passage. In this internal combustion engine 2, a fuel injection valve 12 is attached to an intake manifold 4 to face an intake passage 6, an O ₂ sensor 14 is attached to an exhaust manifold 8 to face an exhaust passage 10, and an ignition plug for igniting and burning an air-fuel mixture 16 is attached.

The O ₂ sensor 14 is, as shown in FIG.
A detection unit 24 in which an atmosphere-side electrode 20 and an exhaust-side electrode 22 are attached to the inside and the outside of the cylindrical solid electrolyte 18 having a lid, respectively.
Is provided, and the detection unit 24 is attached to the exhaust manifold 8 so as to face the exhaust passage 10. The O ₂ sensor 14 generates an electromotive force according to the ratio of the oxygen concentrations of the atmosphere contacting the inside of the detection unit 24 and the exhaust gas contacting the outside.

The fuel injection valve 12 and the O ₂ sensor 14
Is connected to a control means 26 which constitutes an exhaust temperature control device. The control means 26 uses the electromotive force corresponding to the ratio of the oxygen concentration in the exhaust gas detected by the O ₂ sensor 14 to determine that the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 2 is the target air-fuel ratio, for example, the theoretical air-fuel ratio. The fuel injection amount INJ of the fuel injection valve 12 is controlled to the basic injection amount INJ ₀ by feedback so that it becomes the range.

As a result, the catalyst (not shown) provided in the exhaust passage 10 on the downstream side of the O ₂ sensor 14 can effectively operate the exhaust gas purification function.

The O ₂ sensor 14 includes a temperature sensor 28.
Is provided. The temperature sensor 28 is provided in the detection unit 24 facing the exhaust passage 10 on the tip side of the O ₂ sensor 14, and detects the temperature T ₁ of the detection unit 24. This temperature sensor 28
Is connected to the control means 26.

When the temperature T ₁ of the detection section 24 detected by the temperature sensor 28 is lower than the set temperature T, the control means 26 outputs O ₂
The fuel injection amount I of the fuel injection valve 12 is adjusted so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio based on the oxygen concentration detected by the sensor 14.
NJ is controlled to the basic injection amount INJ _0, and the temperature T ₁ of the detector 24 detected by the temperature sensor 28 is set to the set temperature T.
When the temperature exceeds the above, the temperature T ₁ of the detection unit 24 and the set temperature T
The fuel injection amount INJ of the fuel injection valve 12 is controlled to increase from the basic injection amount INJ ₀ according to the difference between

The fuel injection amount INJ is set to the basic injection amount INJ.
_The rate of increase from ₀ is set according to the difference between the temperature T ₁ of the detection unit 24 that has become equal to or higher than the set temperature T and the set temperature T. In this embodiment, the rate of increase is shown in FIG.
As shown in FIG. 5, the value (T ₁ −T = t) of the temperature T ₁ of the detection unit 24 exceeding the set temperature T is large or small (A <... <G).
The table of the increased injection amount α of the value (a <... <g) corresponding to the above is set.

[0023] The control means 26, when the temperature T ₁ of the detector 24 for detecting the temperature sensor 28 is equal to or greater than the set temperature T, the temperature T ₁ of the detection unit 24 from the table shown in FIG. 2
Is calculated according to the difference between the set temperature T and the set temperature T, and a fuel injection amount INJ obtained by adding the increased injection amount α to the basic injection amount INJ ₀ is injected to control the exhaust temperature.

Next, the operation will be described.

As shown in FIG. 1, when the control is started (step 100), the control means 26 sets N = 0 (step 102) and sets the fuel injection amount INJ to INJ = INJ ₀ +
It is calculated by N × α (step 104). The fuel injection amount INJ is N = 0 at this point (step 102)
As a result, the basic injection amount INJ ₀ is achieved without being increased.

Next, it is judged whether or not the temperature T ₁ of the detecting portion 24 of the O ₂ sensor 14 is equal to or higher than the set temperature T (T≤T ₁ ) (step 106). In step 106, if the temperature T ₁ of the detection unit 24 is lower than the set temperature T (step 106: NO), N is set to “0” (N = N) (step 108) and the process returns to step 104.

In step 104, the fuel injection amount I
NJ is calculated by INJ = INJ ₀ + N × α. Since the fuel injection amount INJ is set to N = 0 (step 108), the basic injection amount INJ ₀ is not increased.
Becomes

As a result, when the temperature T ₁ of the detection section 24 detected by the temperature sensor 28 is lower than the set temperature T degrees, the air-fuel ratio of the air-fuel mixture becomes equal to the target air-fuel ratio based on the oxygen concentration detected by the O ₂ sensor 14. Fuel injection amount IN of the fuel injection valve 12
J is controlled to the basic injection amount INJ ₀ , and the fuel is injected from the fuel injection valve 12.

On the other hand, in step 106, O ₂
When the temperature T ₁ of the detection unit 24 of the sensor 14 is equal to or higher than the set temperature T (step 106: YES), 1 is added to the current N = 0 to obtain a new N (N = N + 1) (step 1
10) and returns to step 104.

In step 104, the fuel injection amount I
NJ is calculated by INJ = INJ ₀ + N × α. The fuel injection amount INJ is N = 1 (step 1
10), the basic injection amount INJ _{0 is set} to 1
The amount is increased by the increased injection amount α of × α.

As described above, when the temperature T ₁ of the detection unit 24 detected by the temperature sensor 28 is equal to or higher than the set temperature T, the fuel injection valve 12 is determined according to the difference between the temperature T ₁ of the detection unit 24 and the set temperature T. The fuel injection amount INJ of the basic injection amount INJ ₀ to N ×
The increase injection amount α of α is controlled to increase, and the fuel is injected from the fuel injection valve 12 to lower the temperature of the exhaust gas.

If the temperature of the exhaust gas decreases due to the injection of the fuel injection amount INJ increased from the basic injection amount INJ ₀ and the temperature T ₁ of the detection unit 24 decreases below the set temperature T, the determination at step 106 is NO. Therefore, N is set to “0” (N = N) (step 108) and the process returns to step 104.

In step 104, the fuel injection amount I
NJ is calculated by INJ = INJ ₀ + N × α. Since the fuel injection amount INJ is N = 0 (step 108) at this time, it is not increased,
It becomes the basic injection amount INJ ₀ .

As described above, in the exhaust gas temperature control device, the temperature T ₁ of the detector 24 detected by the temperature sensor 28 is set to the set temperature T _1.
In the above case, the fuel injection amount INJ of the fuel injection valve 12 is increased by the increase injection amount α of N × α from the basic injection amount INJ ₀ according to the difference between the temperature T ₁ of the detection unit 24 and the set temperature T. Control repeatedly.

As a result, the exhaust gas temperature control device controls the temperature of the exhaust gas by injecting the fuel injection amount INJ increased from the basic injection amount INJ ₀ according to the difference between the temperature T ₁ of the detection unit 24 and the set temperature T. The temperature of the exhaust gas can be lowered, the temperature of the exhaust gas can be maintained below the set temperature T, and the O ₂ sensor 14 can be prevented from being exposed to the high temperature exhaust gas.

Therefore, the exhaust gas temperature control device for the internal combustion engine 2 can prevent the deterioration of the O ₂ sensor 14 due to the high temperature exhaust gas, and the exhaust manifold 8 and the O ₂ sensor 14 to which the O ₂ sensor 14 is attached can be prevented. It is also possible to prevent deterioration of a catalyst (not shown) arranged in the exhaust passage 10 on the downstream side of.

The fuel injection amount INJ is the basic injection amount IN.
The rate of increase from J ₀ is as shown in FIG.
The value of the temperature T _{1 of} 4 exceeds the set temperature T (T ₁
By setting the table of the increased injection amount α according to −T = t), the increased injection amount α can be increased in accordance with the value t of the excess, and the value t of the exhaust gas temperature over.
It can be lowered promptly according to.

Further, each time the temperature T ₁ of the detection section 24 of the O ₂ sensor 14 becomes equal to or higher than the set temperature T, 1 is added to the present N to obtain a new N (N = N + 1), so that the set temperature is set. The increased injection amount α can be increased according to the number N of times T has been exceeded, and can be rapidly reduced according to the number N of times the temperature of exhaust gas has been exceeded.

5 to 8 show an embodiment of the second structure of the present invention. In FIG. 7, 2 is an internal combustion engine mounted in a vehicle or the like (not shown), 4 is an intake manifold, and 6 is an intake manifold.
Is an intake passage, 8 is an exhaust manifold, and 10 is an exhaust passage. In this internal combustion engine 2, a fuel injection valve 12 is attached to an intake manifold 4 to face an intake passage 6, an O ₂ sensor 14 is attached to an exhaust manifold 8 to face an exhaust passage 10, and an ignition plug for igniting and burning an air-fuel mixture 16 is attached, and an ignition advance value sensor 30 for detecting an ignition advance value determining factor such as an engine speed or a load for determining the ignition advance value is provided.

The O ₂ sensor 14 is, as shown in FIG.
A detection unit 24 in which an atmosphere-side electrode 20 and an exhaust-side electrode 22 are attached to the inside and the outside of the cylindrical solid electrolyte 18 having a lid, respectively.
Is provided, and the detection unit 24 is attached to the exhaust manifold 8 so as to face the exhaust passage 10. The O ₂ sensor 14 generates an electromotive force according to the ratio of the oxygen concentrations of the atmosphere contacting the inside of the detection unit 24 and the exhaust gas contacting the outside.

The fuel injection valve 12, the O ₂ sensor 14, the spark plug 16, and the ignition advance value sensor 30 are connected to a control means 26 which constitutes an exhaust temperature control device.

The control means 26 determines that the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 2 is the target air-fuel ratio based on the electromotive force corresponding to the ratio of the oxygen concentration in the exhaust gas detected by the O ₂ sensor 14, for example. The fuel injection amount INJ of the fuel injection valve 12 is controlled by feedback to the basic injection amount INJ ₀ so that the stoichiometric air-fuel ratio range is reached. As a result, the catalyst (not shown) provided in the exhaust passage 10 on the downstream side of the O ₂ sensor 14 is
The exhaust gas purification function can be effectively operated.

The control means 26 controls the ignition timing IGT of the spark plug 16 to the basic ignition advance value IGT ₀ based on the ignition advance value determinant detected by the ignition advance value sensor 30. As a result, the spark plug 16 is fired at an appropriate time, and the air-fuel mixture can be appropriately ignited and burned.

The O ₂ sensor 14 includes a temperature sensor 28.
Is provided. The temperature sensor 28 is provided in the detection unit 24 facing the exhaust passage 10 on the tip side of the O ₂ sensor 14, and detects the temperature T ₁ of the detection unit 24. This temperature sensor 28
Is connected to the control means 26.

When the temperature T ₁ of the detecting section 24 detected by the temperature sensor 28 is lower than the set temperature T, the control means 26 outputs O.
₂ Based on the oxygen concentration detected by the sensor 14, the fuel injection amount INJ of the fuel injection valve 12 is controlled to the basic injection amount INJ ₀ so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio, and the ignition advance value sensor 30 detects it. The ignition timing IGT of the spark plug 16 is controlled to become the basic ignition advance value IGT ₀ based on the ignition advance value determinant, and the temperature T ₁ of the detection unit 24 detected by the temperature sensor 28 becomes equal to or higher than the set temperature T. In the case of, the fuel injection amount INJ of the fuel injection valve 12 is set to the basic injection amount INJ according to the difference between the temperature T ₁ of the detection unit 24 and the set temperature T.
The temperature T _{1 of the} detector 24 is controlled so as to increase from _0.
The ignition timing IGT of the spark plug 16 is controlled to be advanced from the basic ignition advance value IGT ₀ according to the difference between the set temperature T and the set temperature T.

The fuel injection amount INJ is set to the basic injection amount INJ.
_The rate of increasing the ignition timing IGT from ₀ and the rate of advancing the ignition timing IGT from the basic ignition advance value IGT ₀ depend on the difference between the temperature T ₁ of the detection unit 24 that is equal to or higher than the set temperature T and the set temperature T. Set. As shown in FIG. 6, the ratio in this embodiment depends on the magnitude (A <... << G) of the value (T ₁ −T = t) of the temperature T ₁ of the detection unit 24 exceeding the set temperature T. Tables of the increased injection amount α and the increased advance value β of the different values (a <... <g, h <... <n) are set.

[0047] The control means 26, when the temperature T ₁ of the detector 24 for detecting the temperature sensor 28 is equal to or greater than the set temperature T, the temperature T ₁ of the detection unit 24 from the table shown in FIG. 6
Of the fuel injection amount INJ obtained by adding the increased injection amount α to the basic injection amount INJ ₀ and determining the increased injection amount α and the increased advance value β according to the difference between the increased advance angle value and the increased injection amount α. Ignition timing IGT obtained by adding β to the basic ignition advance value IGT ₀
Control to lower the exhaust temperature.

Next, the operation will be described.

As shown in FIG. 5, when the control is started (step 200), the control means 26 sets N = 0 (step 202) and sets the fuel injection amount INJ to INJ = INJ ₀ +.
Calculated by N × α (step 204), ignition timing IG
T is calculated by IGT = IGT ₀ + N × β (step 206).

The fuel injection amount INJ is N = 0 (step 2
02), the basic injection amount INJ ₀ is not increased. Further, the ignition timing IGT is N
By setting = 0 (step 202), the basic ignition advance value IGT ₀ is obtained without advance.

Next, it is judged whether or not the temperature T ₁ of the detecting portion 24 of the O ₂ sensor 14 is equal to or higher than the set temperature T (T≤T ₁ ) (step 208). In step 208, if the temperature T ₁ of the detection unit 24 is lower than the set temperature T (step 208: NO), N is set to “0” (N = N) (step 210) and the process returns to step 204.

In step 204, the fuel injection amount I
NJ is calculated by INJ = INJ ₀ + N × α. Since the fuel injection amount INJ is set to N = 0 (step 210), the basic injection amount INJ ₀ is not increased.
Becomes

In step 206, the ignition timing IG
T is calculated by IGT = IGT ₀ + N × β. Since the ignition timing IGT is set to N = 0 (step 210), the basic ignition advance value IGT ₀ is not advanced.
become.

As a result, when the temperature T ₁ of the detector 24 detected by the temperature sensor 28 is less than the set temperature T degrees, the air-fuel ratio of the air-fuel mixture becomes equal to the target air-fuel ratio based on the oxygen concentration detected by the O ₂ sensor 14. Fuel injection amount IN of the fuel injection valve 12
J is controlled to the basic injection amount INJ ₀ , and the ignition timing IGT of the spark plug 16 is controlled to the basic ignition advance value IGT ₀ based on the ignition advance value determinant detected by the ignition advance value sensor 30.

On the other hand, in step 208, O ₂
When the temperature T ₁ of the detection unit 24 of the sensor 14 is equal to or higher than the set temperature T (step 208: YES), 1 is added to the current N = 0 to obtain a new N (N = N + 1) (step 2
12) and returns to step 204.

In step 204, the fuel injection amount I
NJ is calculated by INJ = INJ ₀ + N × α. The fuel injection amount INJ is N = 1 at this point (step 2
12), the basic injection amount INJ _{0 is set} to 1
The amount is increased by the increased injection amount α of × α.

In step 206, the ignition timing IG
T is calculated by IGT = IGT ₀ + N × β. The ignition timing IGT is N = 1 (step 21
By setting 2), the basic ignition advance value IGT ₀ is advanced by the increased advance value β of 1 × β.

As described above, when the temperature T ₁ of the detection unit 24 detected by the temperature sensor 28 is lower than the set temperature T, the fuel injection valve 12 is determined according to the difference between the temperature T ₁ of the detection unit 24 and the set temperature T. The fuel injection amount INJ of the basic injection amount INJ ₀ to N ×
The fuel is injected from the fuel injection valve 12 while being controlled to increase by the increased injection amount α of α, and the ignition timing I of the spark plug 16 is increased.
The GT is controlled so as to advance from the basic ignition advance value IGT _{0 by} the increased advance value β of N × β to cause the spark plug 16 to ignite, thereby lowering the temperature of the exhaust gas.

Due to the injection of the fuel injection amount INJ increased from the basic injection amount INJ ₀ and the ignition timing IGT advanced from the basic ignition advance value IGT ₀ , the temperature of the exhaust gas is lowered, and the temperature of the detector 24 is lowered. When T ₁ drops below the set temperature T, the determination in step 208 becomes NO, so N is set to “0” (N = N) (step 21
0), and returns to step 204.

In step 204, the fuel injection amount I
NJ is calculated by INJ = INJ ₀ + N × α. Since the fuel injection amount INJ is N = 0 (step 210) at this point, it is not increased,
It becomes the basic injection amount INJ ₀ .

In step 206, the ignition timing IG
T is calculated by IGT = IGT ₀ + N × β. The ignition timing IGT is N = 0 at this point (step 21
By setting 0), the basic ignition advance value IGT ₀ is obtained without advancement.

As described above, in the exhaust gas temperature control device, the temperature T ₁ of the detection section 24 detected by the temperature sensor 28 is set to the set temperature T _1.
In the above case, the fuel injection amount INJ of the fuel injection valve 12 is increased by the increase injection amount α of N × α from the basic injection amount INJ ₀ according to the difference between the temperature T ₁ of the detection unit 24 and the set temperature T. The ignition timing IGT of the ignition plug 16 is controlled repeatedly and according to the difference between the temperature T ₁ of the detector 24 and the set temperature T.
Is repeatedly controlled to advance the basic ignition advance value IGT _{0 by} the increased advance value β of N × β.

As a result, the exhaust temperature control device causes the injection amount and the basic ignition advance value of the fuel injection amount INJ increased from the basic injection amount INJ ₀ according to the difference between the temperature T ₁ of the detector 24 and the set temperature T. The temperature of the exhaust gas can be rapidly lowered by the ignition timing IGT that is advanced from IGT ₀ , the temperature of the exhaust gas can be maintained below the set temperature T, and the O ₂ sensor 14 is exposed to high temperature exhaust gas. Can be reliably prevented.

Therefore, the exhaust gas temperature control device for the internal combustion engine 2 can more accurately prevent the deterioration of the O ₂ sensor 14 due to the high temperature exhaust gas, and the exhaust manifold 8 and the O ₂ sensor 14 to which the O ₂ sensor 14 is attached. ₍₂ ) It is possible to more appropriately prevent deterioration of a catalyst (not shown) arranged in the exhaust passage 10 on the downstream side of the sensor 14.

The fuel injection amount INJ is equal to the basic injection amount IN
Proportion to advance the rate and the ignition timing IGT from the basic ignition advance value IGT ₀ increase from J _0, as shown in FIG. 6, the temperature T ₁ of the detector 24 has exceeded the set temperature T of the frequency values ( By setting the table of the increased injection amount α and the increased advance value β according to T ₁ −T = t), the increased injection amount α and the increased advance value β are changed according to the value t of the excess. The temperature of the exhaust gas can be increased, and the exhaust gas temperature can be rapidly decreased in accordance with the value t.

Further, each time the temperature T ₁ of the detecting portion 24 of the O ₂ sensor 14 becomes equal to or higher than the set temperature T, 1 is added to the present N to obtain a new N (N = N + 1). It is possible to increase the increased injection amount α and the increased advance value β in accordance with the number N of times that the exhaust gas has exceeded, and it is possible to quickly decrease the exhaust gas temperature according to the number of times N that the exhaust gas temperature has been exceeded.

[0067]

As described above, the exhaust gas temperature control device of the first configuration of the present invention responds to the difference between the detection part temperature and the set temperature when the detection part temperature of the O ₂ sensor exceeds the set temperature. By controlling the fuel injection amount of the fuel injection valve to increase from the basic injection amount, the high temperature exhaust gas O _{2 is} increased by the fuel injection amount increased from the basic injection amount according to the difference between the detection unit temperature and the set temperature. The temperature can be lowered to a temperature at which the sensor can function properly, and the O ₂ sensor can be prevented from being exposed to hot exhaust gas.

Therefore, this exhaust gas temperature control device for an internal combustion engine can prevent the O ₂ sensor from deteriorating due to high temperature exhaust gas, and can be installed on the exhaust manifold to which the O ₂ sensor is attached or on the downstream side of the O ₂ sensor. It can also prevent deterioration of the catalyst provided.

Further, in the exhaust gas temperature control device of the second configuration of the present invention, when the temperature of the detecting portion of the O ₂ sensor becomes equal to or higher than the set temperature, the fuel injection valve is operated according to the difference between the temperature of the detecting portion and the set temperature. The fuel injection amount of the control unit is controlled to increase from the basic injection amount, and the ignition timing of the spark plug is controlled to advance from the basic ignition advance value according to the difference between the detection unit temperature and the set temperature. Depending on the difference between the temperature and the set temperature, the fuel injection amount increased from the basic injection amount and the ignition timing advanced from the basic ignition advance value can quickly bring the high temperature exhaust gas to a temperature at which the O ₂ sensor can properly function. It is possible to reliably prevent the O ₂ sensor from being exposed to hot exhaust gas.

Therefore, this exhaust gas temperature control device for an internal combustion engine can more accurately prevent the deterioration of the O ₂ sensor due to the high temperature exhaust gas, and the exhaust manifold to which the O ₂ sensor is attached and the downstream of the O ₂ sensor. It is possible to more appropriately prevent deterioration of the catalyst disposed on the side.

[Brief description of drawings]

FIG. 1 is a control flowchart showing an embodiment of an exhaust gas temperature control device for an internal combustion engine according to the first configuration of the present invention.

FIG. 2 is a diagram showing a relationship between an increased injection amount and a difference between a detection unit temperature and a set temperature.

FIG. 3 is a schematic configuration diagram of an exhaust temperature control device.

FIG. 4 is a sectional view of an O ₂ sensor provided with a temperature sensor.

FIG. 5 is a control flowchart showing an embodiment of an exhaust gas temperature control device for an internal combustion engine according to the second configuration of the present invention.

FIG. 6 is a diagram showing the relationship between the increased injection amount and the increased advance value with respect to the difference between the detection unit temperature and the set temperature.

FIG. 7 is a schematic configuration diagram of an exhaust temperature control device.

FIG. 8 is a sectional view of an O ₂ sensor provided with a temperature sensor.

FIG. 9 is a schematic configuration diagram of a fuel injection control device showing a conventional example.

FIG. 10 is a sectional view of an O ₂ sensor.

[Explanation of symbols]

2 Internal Combustion Engine 6 Intake Passage 10 Exhaust Passage 12 Fuel Injection Valve 14 O ₂ Sensor 16 Spark Plug 24 Detector 26 Control Means 28 Temperature Sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 43/00 B F02P 5/15 G01N 27/26 361 C 27/409

Claims (2)

[Claims] 1. A fuel injection valve for injecting fuel is provided in an intake passage of the internal combustion engine, provided the O ₂ sensor for detecting the oxygen concentration in the exhaust gas in an exhaust passage of the internal combustion engine, the exhaust passage of the O ₂ sensor a temperature sensor for detecting a detection part temperature facing provided, and the air-fuel ratio the target air-fuel ratio of the mixture if the detection unit temperature is lower than the set temperature on the basis of the oxygen concentration detecting the O ₂ sensor for detecting the temperature sensor The fuel injection amount of the fuel injection valve is controlled to be a basic injection amount so that when the detection part temperature detected by the temperature sensor is equal to or higher than a set temperature, it is determined according to a difference between the detection part temperature and the set temperature. An exhaust gas temperature control device for an internal combustion engine, comprising: a control means for controlling the fuel injection amount of the fuel injection valve to increase from a basic injection amount. 2. A fuel injection valve for injecting fuel to an intake passage of an internal combustion engine, an ignition plug for igniting and burning an air-fuel mixture supplied to the internal combustion engine, and an ignition advance value deciding factor for the internal combustion engine. An ignition advance sensor for detecting O ₂ is provided in the exhaust passage of the internal combustion engine to detect the oxygen concentration in the exhaust gas.
The sensor is provided, the O ₂ a temperature sensor for detecting a detection part temperature the faces in an exhaust passage of the sensor is provided, the O ₂ when detection part temperature detected by the temperature sensor is lower than the set temperature
Based on the oxygen concentration detected by the sensor, the fuel injection amount of the fuel injection valve is controlled to the basic injection amount so that the air-fuel ratio of the air-fuel mixture becomes the target air-fuel ratio, and the ignition advance value detected by the ignition advance value sensor is determined. Based on a factor, the ignition timing of the spark plug is controlled to be a basic ignition advance value, and when the detection temperature detected by the exhaust gas temperature sensor exceeds a set temperature, the detection temperature and the set temperature are The fuel injection amount of the fuel injection valve is controlled to increase from the basic injection amount according to the difference, and the ignition timing of the spark plug is advanced from the basic ignition advance value according to the difference between the detection unit temperature and the set temperature. An exhaust gas temperature control device for an internal combustion engine, which is provided in a control means for controlling to turn the exhaust gas.