JP4367234B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine. In particular, the present invention relates to an apparatus including a port injection valve that injects fuel into an intake port and an in-cylinder injection valve that injects fuel into a combustion chamber.

  A port injection valve that injects fuel into the intake port and an in-cylinder injection valve that injects fuel into the combustion chamber. The fuel is injected from the port injection valve and the in-cylinder injection valve at an injection ratio determined according to operating conditions. Has been developed, that is, a double injection type internal combustion engine. For example, there exists a thing of patent document 1.

When an internal combustion engine is used for a vehicle, an air-fuel ratio sensor is often provided in the exhaust pipe, and the air-fuel ratio is often feedback controlled based on the output of the air-fuel ratio sensor. The output of the air-fuel ratio sensor was found to change depending on the hydrogen concentration in the exhaust gas.
Therefore, in Patent Document 2, a pressure sensor capable of detecting the pressure in the combustion chamber is provided, the hydrogen concentration is estimated based on the change in the pressure in the combustion chamber detected by the pressure sensor, and the output of the air-fuel ratio sensor is output according to the estimated hydrogen concentration. The correction is disclosed.

  Further, Patent Document 3 discloses that a hydrogen sensor for detecting the hydrogen concentration in the exhaust gas is provided to obtain the air-fuel ratio based on the concentration of the hydrogen sensor detected by the hydrogen sensor.

  On the other hand, FIG. 14 is a diagram showing the hydrogen concentration in the case of port injection and the hydrogen concentration in the case of in-cylinder injection in a double injection internal combustion engine having a port injection valve and an in-cylinder injection valve as in Patent Document 1. . As is clear from the figure, when the injection ratio is different, the hydrogen concentration is different, and the output of the air-fuel ratio sensor is shifted accordingly.

  However, Patent Documents 2 and 3 do not mention the case of a double injection type internal combustion engine having such a port injection valve and a cylinder injection valve, and a double injection type internal combustion engine having a port injection valve and a cylinder injection valve. There is nothing in the engine that makes it possible to use the air-fuel ratio sensor with high reliability.

JP 2000-364409 A JP-A-9-268934 JP 2000-8920 A

  An object of the present invention is to make it possible to use an air-fuel ratio sensor with high reliability in an internal combustion engine having a port injection valve and a cylinder injection valve.

According to the first aspect of the present invention, a port injection valve for injecting fuel into the intake port and a cylinder injection valve for injecting fuel into the combustion chamber are provided, and operating conditions are determined from the port injection valve and the cylinder injection valve. An internal combustion engine that injects fuel at a ratio determined in accordance with it, detecting an air-fuel ratio of exhaust gas with an air-fuel ratio sensor and controlling the air-fuel ratio based on the output of the air-fuel ratio sensor,
An injection amount ratio calculating means for calculating an injection amount ratio that is a ratio of the port injection amount and the in-cylinder injection amount;
Air-fuel ratio sensor output correcting means for correcting the output of the air-fuel ratio sensor based on the injection amount ratio calculated by the injection amount ratio calculating means , wherein the cylinder for the total injection amount that is the sum of the in-cylinder injection amount and the port injection amount Air-fuel ratio sensor output correction means for correcting the air-fuel ratio detected by the air-fuel ratio sensor in a direction of increasing as the injection ratio of the internal injection amount increases ,
An internal combustion engine is provided that controls the air-fuel ratio based on the output of the air-fuel ratio sensor corrected by the air-fuel ratio sensor output correcting means.
The internal combustion engine configured as described above includes a port injection valve that injects fuel into the intake port and an in-cylinder injection valve that injects fuel into the combustion chamber. And the in-cylinder injection amount ratio, and the air-fuel ratio sensor output correction means corrects the output of the air-fuel ratio sensor based on the injection amount ratio calculated by the injection amount ratio calculation means. The air / fuel ratio is controlled based on the output of the air / fuel ratio sensor corrected by the correcting means.

  According to the invention of claim 2, in the invention of claim 1, the air-fuel ratio sensor output correcting means estimates the hydrogen concentration in the exhaust gas based on the injection amount ratio, and the air-fuel ratio sensor based on the estimated hydrogen concentration. The output is corrected.

According to the invention of claim 3, in the invention of claim 1, the air-fuel ratio sensor output correcting means further includes a water temperature correcting means for correcting the output of the air-fuel ratio sensor in accordance with the cooling water temperature. .

According to the invention of claim 4, in the invention of claim 1, the internal combustion engine includes an intake valve timing adjustment mechanism for adjusting the valve opening period of the intake valve and an exhaust valve timing adjustment mechanism for adjusting the valve opening period of the exhaust valve. Have one or both,
The air-fuel ratio sensor output correction means further includes intake / exhaust valve timing correction means for correcting the output of the air-fuel ratio sensor in accordance with the relationship between the valve opening period of the intake valve and the valve opening period of the exhaust valve.

According to the first aspect of the present invention, the fuel injection device includes the port injection valve that injects fuel into the intake port and the in-cylinder injection valve that injects fuel into the combustion chamber. An injection amount ratio that is a ratio of the in-cylinder injection amount is calculated, and the air-fuel ratio sensor output correction means corrects the output of the air-fuel ratio sensor based on the injection amount ratio calculated by the injection amount ratio calculation means, and the air-fuel ratio sensor output correction The air-fuel ratio is controlled based on the output of the air-fuel ratio sensor corrected by the means, and the air-fuel ratio sensor can be used with high reliability.
According to the invention of claim 3 , the output of the air-fuel ratio sensor is also corrected by the water temperature, and the reliability is further high.
According to the invention of claim 4 , the output of the air-fuel ratio sensor is corrected according to the relationship between the valve opening period of the intake valve and the valve opening period of the exhaust valve, and the reliability is high.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram for explaining the hardware configuration of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a hardware configuration common to the embodiments of the present invention.
Reference numeral 1 denotes a spark ignition internal combustion engine. The internal combustion engine 1 includes a cylinder head 1a and a cylinder block 1b. The cylinder head 1 a includes an intake port 5, an exhaust port 6, an intake valve 7, an exhaust valve 8, and an ignition plug 40, and a high voltage current is supplied to the ignition plug 40 from an ignition coil 41.

  The piston 2 connected to the crankshaft 3 reciprocates in the cylinder block 1b, and a combustion chamber 1c is formed between the piston 2 and the cylinder head 1a. A crank angle sensor 52 is attached to the cylinder block 1b, and the engine speed is calculated based on a signal from the crank angle sensor 52. A water temperature sensor 53 for detecting the cooling water temperature is attached to the cylinder block 1b.

  An intake valve timing adjustment device 70 that adjusts the phase of the valve opening period of the intake valve 7 in accordance with operating conditions is attached to the intake cam 7c. Similarly, an exhaust valve timing adjusting device 80 that adjusts the phase of the valve opening period of the exhaust valve 8 in accordance with operating conditions is attached to the exhaust cam 8c.

FIG. 2 is a diagram for explaining the structure of the intake valve timing adjustment device 70 and the exhaust valve timing adjustment device 80.
The intake valve timing adjusting device 70 has a housing part 71 and a vane part 72. The housing part 71 is fixed to a gear 75 driven by the crankshaft 3 (see FIG. 1) via a chain (not shown). The vane portion 72 is fixed to the intake camshaft 7c.

  Three hydraulic chambers 73 are formed inside the housing portion 71, and three vanes 74 of the vane portion 72 are arranged in each hydraulic chamber 73. The angular width of the hydraulic chamber 73 is larger than the angular width of the vane 74, and the hydraulic chamber 73 is separated into an advance side hydraulic chamber 73a and a retard side hydraulic chamber 73r with the vane 74 interposed therebetween.

  When the engine is stopped, the advance-side hydraulic chamber 73a is minimized and the retard-side hydraulic chamber 73r is maximized by an urging mechanism (not shown), and is set to the most retarded phase. During operation, the hydraulic pressure acting on the advance side hydraulic chamber 73a and the retard side hydraulic chamber 73r is adjusted via an oil control valve (not shown) so that an optimum phase is obtained for the operating conditions. Therefore, although not shown, a cam position sensor for detecting the cam position is attached.

  Similarly, the exhaust valve timing adjusting device 80 has a housing part 81 and a vane part 82. The housing part 81 is fixed to a gear 85 driven by the crankshaft 3 (see FIG. 1) via a chain (not shown). The vane portion 82 is fixed to the exhaust camshaft 8c.

  Four hydraulic chambers 83 are formed inside the housing portion 81, and four vanes 84 of the vane portion 82 are arranged in each hydraulic chamber 83. The angular width of the hydraulic chamber 83 is larger than the angular width of the vane 84, and the hydraulic chamber 83 is separated into an advance side hydraulic chamber 83a and a retard side hydraulic chamber 83r with the vane 84 interposed therebetween.

  When the engine is stopped, the advance side hydraulic chamber 83a is maximized and the retard angle side hydraulic chamber 83r is minimized by an urging mechanism (not shown). During operation, the hydraulic pressure acting on the advance side hydraulic chamber 83a and the retard side hydraulic chamber 83r is adjusted via an oil control valve (not shown) so that an optimum phase is obtained for the operating conditions. Therefore, although not shown, a cam position sensor for detecting the cam position is attached.

  In FIG. 1, a port injection valve 31 for injecting fuel into the intake port 5 and an in-cylinder injection valve 32 for injecting fuel into the combustion chamber 1c are attached to the cylinder head 1a. Fuel is fed from the fuel tank 30 to the port injection valve 31 and the in-cylinder injection valve 32 by a fuel pump (not shown) through a fuel pipe (not shown).

  An intake pipe 10 is connected to the intake port 5, and an air cleaner 11 is attached to the upstream end of the intake pipe 10. An air flow meter 51 for detecting the intake air amount is disposed immediately downstream of the air cleaner 11. A throttle valve 12 is disposed downstream of the air flow meter 51. The throttle valve 12 is driven by a throttle motor 13. On the other hand, an accelerator pedal sensor 50 for detecting the depression amount of the accelerator pedal 14 is attached to the accelerator pedal 14, and the throttle valve 12 is operated by the throttle motor 13 in accordance with the depression amount of the accelerator pedal 14 detected by the accelerator pedal sensor 50. The degree of opening is changed.

  An exhaust pipe 20 is connected to the exhaust port 6, and a three-way catalyst 21 is disposed in the exhaust pipe 20. A first air-fuel ratio sensor 22 is disposed near the upstream side of the three-way catalyst 21, and a second air-fuel ratio sensor 23 is disposed near the downstream side of the three-way catalyst 21. The exhaust gas generated in the combustion chamber 1a is led to the exhaust pipe 20 through the exhaust port 6 whose flow path is opened and closed by the exhaust valve 8, is purified by the three-way catalyst 21, and is discharged. The fuel injection amounts injected from the port injection valve 31 and the in-cylinder injection valve 32 are feedback-controlled so that a predetermined air-fuel ratio is obtained based on the outputs of the first air-fuel ratio sensor 22 and the second air-fuel ratio sensor 23.

  Reference numeral 24 indicates a hydrogen concentration sensor, and this hydrogen concentration sensor 24 is provided and used only in the third embodiment. The hydrogen concentration sensor 24 will not be described in detail. For example, as described in Patent Document 3, the hydrogen concentration sensor 24 includes a catalyst layer that selectively reacts with hydrogen and a catalyst layer that does not react with hydrogen, and a temperature difference between these two layers. From this, the hydrogen concentration is detected.

  An electronic control unit (hereinafter referred to as ECU) 100 is formed by connecting an input port 101, an output port 102, a CPU 103, a ROM 104, a RAM 105, and the like with a common bus. A signal detected by each sensor is input to the ECU 100, and a control signal for performing control related to the present invention is sent to each actuator.

Hereinafter, in each embodiment of the present invention having the basic hardware configuration as described above, control for correcting the outputs of the air-fuel ratio sensors (the first air-fuel ratio sensor 22 and the second air-fuel ratio sensor 23). Will be described.
First, the control of the first embodiment will be described. In the first embodiment, the injection ratio between the port injection amount and the in-cylinder injection amount (numerically expressed as [in-cylinder injection amount] / [port injection amount + in-cylinder injection amount]) is obtained. Estimate the hydrogen concentration in the ratio, correct the estimated hydrogen concentration based on the cooling water temperature and the timing of the intake valve and exhaust valve (substantially the overlap amount), and the air-fuel ratio with respect to the corrected hydrogen concentration The correction value of the sensor is obtained.

FIG. 3 is a flowchart for performing the control of the first embodiment as described above.
In step S101, parameters (air-fuel ratio AF, port injection time TAUP, in-cylinder injection time TAUD, cooling water temperature THW, advance amount AINA from the most retarded position of intake valve timing adjustment device 70, exhaust valve timing adjustment device 80 The retard amount AEXR from the most advanced position is read.

  In step S102, an injection ratio RPD is calculated. This is expressed as a ratio of the valve opening time TAUD of the cylinder injection valve 32 to the sum of the valve opening time TAUD of the cylinder injection valve 32 and the valve opening time TAUP of the port injection valve 31. That is, RPD = TAUD / (TAUD + TAUP).

In step S103, the hydrogen concentration H in the exhaust gas when operating at the injection ratio RPD stopped in step S102 is estimated from the map of FIG.
In step S104, a water temperature correction coefficient KHW for correcting the hydrogen concentration H stopped in step S103 according to the cooling water temperature is calculated from the map of FIG. 7 using the water temperature THW read in step S101.
In step S105, the intake valve timing adjustment device that has read in step S101 the intake / exhaust valve timing correction coefficient KHV for correcting the hydrogen concentration H stopped in step S103 in accordance with the opening timing of the intake valve 7 and the exhaust valve 8. It is calculated from the map of FIG. 8 using the advance amount AINA from the most retarded position of 70 and the retard amount AEXR from the most advanced position of the exhaust valve timing adjusting device 80.

In step S106, the hydrogen concentration H stopped in step S103 is multiplied by the water temperature correction coefficient KHW calculated in step S104 and the intake / exhaust valve timing correction coefficient KHV calculated in step S105 to calculate a corrected hydrogen concentration Hc.
In step S107, the air-fuel ratio correction amount CAF at the corrected hydrogen concentration Hc stopped in step S106 is calculated from the map of FIG.
In step S108, the corrected air-fuel ratio AFc is calculated by adding the air-fuel ratio correction amount CAF calculated in step S108 to the air-fuel ratio AF read in step S101.
The first embodiment operates as described above to correct the outputs of the first air-fuel ratio sensor 22 and the second air-fuel ratio sensor 23.

Next, a second embodiment will be described.
In the first embodiment, the hydrogen concentration H at the detected injection ratio RPD is estimated, and this hydrogen concentration H is corrected by correcting the hydrogen temperature H with the water temperature correction coefficient KHW and the intake / exhaust valve timing correction coefficient KHV. The air-fuel ratio correction coefficient CAF for the hydrogen concentration Hc is calculated, and the air-fuel ratio correction coefficient CAF is added to the air-fuel ratio AF detected by the air-fuel ratio sensor to correct the air-fuel ratio AF detected by the air-fuel ratio sensor.
In contrast, in the second embodiment, without estimating the hydrogen concentration H, the injection ratio correction coefficient KARPD, the water temperature correction coefficient KAW, and the intake / exhaust valve timing correction coefficient KAV for the air-fuel ratio AF detected by the air-fuel ratio sensor. And multiplying them to correct the air-fuel ratio AF detected by the air-fuel ratio sensor.

FIG. 4 shows a flowchart of control in the second embodiment.
Step S201 and step S202 are the same as step S101 and step S102 in the flowchart of the first embodiment.
In step S203, an injection ratio correction coefficient KARPD corresponding to the injection ratio RPD for the air-fuel ratio AF is calculated from the map of FIG. In step S204, the water temperature correction coefficient KAW for the air-fuel ratio AF is calculated from the map of FIG. 11 using the water temperature THW read in step S201. In step S205, the advance amount AINA from the most retarded position of the intake valve timing adjusting device 70 read in step S201 and the retard amount AEXR from the most advanced position of the exhaust valve timing adjusting device 80 are used as shown in FIG. An intake / exhaust valve timing correction coefficient KAV for the air-fuel ratio AF is calculated from the map.

In step S206, the injection ratio correction coefficient KARPD calculated in step S203, the water temperature correction coefficient KAW calculated in step S203, and the valve overlap correction coefficient KOL calculated in step S203 are added to the air-fuel ratio AF detected by the air-fuel ratio sensor. Multiplication is performed to correct the air-fuel ratio AF detected by the air-fuel ratio sensor.
The second embodiment operates as described above, and compared with the first embodiment, the calculation load is reduced by directly correcting the air-fuel ratio AF detected by the air-fuel ratio sensor.

Next, a third embodiment will be described.
This third embodiment is provided with a hydrogen concentration sensor 24, and for the hydrogen concentration H detected by the hydrogen concentration sensor 24, the air-fuel ratio is calculated from the map of FIG. 9 in the same manner as in step S107 of the flowchart of the first embodiment. The correction amount CAF is calculated, and this air-fuel ratio correction amount CAF is added to the AF detected by the air-fuel ratio sensor to calculate the correction air-fuel ratio AFc.

However, it has a feature that a failure diagnosis of the hydrogen concentration sensor 24 is executed.
In this failure diagnosis, the rotational speed and load (for example, intake air amount) are detected, and the difference between the hydrogen concentration when the port injection is 100% and the hydrogen concentration when the cylinder injection is 100% is stored in advance. Get from the map that is. On the other hand, assuming that port injection is actually 100% and in-cylinder injection is 100%, the hydrogen concentration in each case is detected and the difference between these two hydrogen concentrations is determined.
If the difference between the hydrogen concentration determined from the map and the actual hydrogen concentration difference exceeds a predetermined value, it is assumed that the hydrogen concentration sensor has failed.

FIG. 5 is a flowchart of the control of the third embodiment based on the above.
In step S301, each detected parameter (revolution speed NE, intake air amount GA, hydrogen concentration HA) is read. In step S302, the theoretical value DHM of the difference in hydrogen concentration between the case of 100% port injection and the case of 100% in-cylinder injection is calculated from the map shown in FIG. This theoretical value is determined using a standard engine at the time of development and stored in the ECU 100.
In step S303, the operation of 100% port injection is executed, and the hydrogen concentration HApf at that time is detected and read. In step S304, the operation of in-cylinder injection 100% is executed, and the hydrogen concentration HAdf at that time is detected and read.

In step S305, the actual value DHA of the difference in hydrogen concentration in the case of port injection 100% and in-cylinder injection 100% is obtained from the difference between the value stopped in step S303 and the value stopped in step S304. That is, DHA = HAdf−HApf is obtained.
In step S306, it is determined whether or not the difference between the DHM stopped in step S302 and the DHA stopped in step S305 is equal to or less than a predetermined value.

If an affirmative determination is made in step S306, the process proceeds to step S307, and the air-fuel ratio correction corresponding to the hydrogen concentration HA determined in step S301 from the same map of FIG. 9 used in step S107 of the flowchart of the first embodiment. The amount CAF is obtained and added to the air-fuel ratio AF read in step S301 in step S308, and the corrected air-fuel ratio AFc is obtained to end.
On the other hand, if a negative determination is made in step S306, it is determined in step S309 that the hydrogen concentration sensor 24 is abnormal, and the process ends.

The third embodiment is configured and operated as described above, and can diagnose the abnormality of the hydrogen concentration sensor 24 by taking advantage of the feature that the port injection valve and the in-cylinder injection valve are provided.
In the above flowchart, when there is an abnormality, the determination of the abnormality ends. However, various measures can be performed thereafter. For example, the correction by the hydrogen concentration sensor 24 may be stopped and the driver may be informed that there is an abnormality in the hydrogen concentration sensor 24.

  The present invention includes a port injection valve that injects fuel into an intake port and an in-cylinder injection valve that injects fuel into a combustion chamber. The port injection valve and the in-cylinder injection valve are determined according to operating conditions. The present invention can be applied to an internal combustion engine that injects fuel at a ratio, in which the air-fuel ratio of exhaust gas is detected by an air-fuel ratio sensor and the air-fuel ratio is controlled based on the output of the air-fuel ratio sensor.

It is a figure which shows the hardware constitutions of embodiment of this invention. It is a figure which shows the structure of an intake valve timing adjustment apparatus and an exhaust valve timing adjustment apparatus. It is a flowchart of control of a 1st embodiment. It is a flowchart of control of a 2nd embodiment. It is a flowchart of control of a 3rd embodiment. It is a figure which shows the relationship between an injection ratio and hydrogen concentration. It is a figure which shows a water temperature correction coefficient (vs. hydrogen concentration). It is a figure which shows an intake / exhaust valve timing correction coefficient (vs. hydrogen concentration). It is a figure which shows the relationship between hydrogen concentration and an air fuel ratio correction value. It is a figure which shows an injection ratio correction coefficient (to air-fuel ratio). It is a figure which shows a water temperature correction coefficient (an air fuel ratio). It is a figure which shows an intake / exhaust valve timing correction coefficient (to air-fuel ratio). It is a figure which shows the hydrogen concentration difference in the case of 100% of port injection, and the case of in-cylinder injection 100. FIG. It is a figure which shows the difference of the hydrogen concentration in the case of port injection and in-cylinder injection.

Explanation of symbols

5 ... Intake port 6 ... Exhaust port 7 ... Intake valve 8 ... Exhaust valve 22 ... First air-fuel ratio sensor 23 ... Second air-fuel ratio sensor 24 ... Hydrogen concentration sensor (third embodiment)
31 ... Port injection valve 32 ... In-cylinder injection valve 33 ... Fuel pipe 40 ... Spark plug 51 ... Crank angle sensor 52 ... Air flow meter 53 ... Water temperature sensor 70 ... Intake valve timing adjustment device 80 ... Exhaust valve timing adjustment device 100 ... ECU ( Electronic control unit)

Claims (4)

A port injection valve that injects fuel into the intake port and an in-cylinder injection valve that injects fuel into the combustion chamber. The fuel is injected from the port injection valve and the in-cylinder injection valve at a ratio determined according to operating conditions. An internal combustion engine that injects, detects an air-fuel ratio of exhaust gas with an air-fuel ratio sensor, and controls the air-fuel ratio based on the output of the air-fuel ratio sensor.
An injection amount ratio calculating means for calculating an injection amount ratio that is a ratio of the port injection amount and the in-cylinder injection amount;
Air-fuel ratio sensor output correcting means for correcting the output of the air-fuel ratio sensor based on the injection amount ratio calculated by the injection amount ratio calculating means , wherein the cylinder for the total injection amount that is the sum of the in-cylinder injection amount and the port injection amount Air-fuel ratio sensor output correction means for correcting the air-fuel ratio detected by the air-fuel ratio sensor in a direction of increasing as the injection ratio of the internal injection amount increases ,
An internal combustion engine for controlling an air-fuel ratio based on an output of an air-fuel ratio sensor corrected by an air-fuel ratio sensor output correcting means.   The air-fuel ratio sensor output correction means estimates the hydrogen concentration in the exhaust gas based on the injection amount ratio, and corrects the output of the air-fuel ratio sensor based on the estimated hydrogen concentration. Internal combustion engine. The internal combustion engine according to claim 1, wherein the air-fuel ratio sensor output correcting means further includes water temperature correcting means for correcting the output of the air-fuel ratio sensor in accordance with the cooling water temperature. The internal combustion engine includes one or both of an intake valve timing adjustment mechanism that adjusts the valve opening period of the intake valve and an exhaust valve timing adjustment mechanism that adjusts the valve opening period of the exhaust valve,
The air-fuel ratio sensor output correction means further includes intake / exhaust valve timing correction means for correcting the output of the air-fuel ratio sensor in accordance with the relationship between the valve opening period of the intake valve and the valve opening period of the exhaust valve. The internal combustion engine according to claim 1.

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