JPH07109947A - Diagnostic device for internal combustion engine and secondary air feeding nevice - Google Patents

Abstract

PURPOSE:To diagnose two kinds of devices by a single flow rate detecting means by installing a commonly used part in the secondary air passage and an EGR passage and installing a flow rate detecting means in the commonly used part, as for an internal combustion engine equipped with the secondary air supply device and an EGR supply device. CONSTITUTION:An internal combustion engine 10 controls the fuel injection quantity of a fuel injector 18 on the basis of each detection signal of the first flow rate detecting means 11 and a revolution speed detecting means 17 and corrects the fuel injection quantity on the basis of the detection signal of an oxygen concentration detecting means 12. In this cass, a secondary air passage 111 and an EGR passage 112 are used in common through a selector valve 14, and the second flow rate detecting means 15 is arranged in the common passage. The secondary air supply quantity and the EGR supply quantity are detected by the second flow rate detecting means 15, and the secondary air feeding device and the EGR supply device are controlled by the internal combustion engine controller 10 on the basis of these detection signals. Accordingly, the secondary air feeding device and the EGR supply device are diagnosed by the single flow rate detecting means 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention combines a secondary air amount detecting means and an EGR amount detecting means in a diagnostic device for a secondary air supply device of an internal combustion engine and a diagnostic device for an EGR amount supply device into one flow rate detecting device. Regarding things.

[0002]

2. Description of the Related Art In a technique for attaching a three-way catalyst to an exhaust system of an internal combustion engine to purify hydrocarbons HC, carbon monoxide CO, and nitrogen oxide compound NOx contained in the exhaust gas, the three-way catalyst can be efficiently purified. In order to control the actual air-fuel ratio centering on the theoretical air-fuel ratio, it is a known technique to install air-fuel ratio detection means in the exhaust system upstream of the three-way catalyst and feed back the oxygen concentration in the exhaust gas to the internal combustion engine. . In addition, when the internal temperature of the three-way catalyst is low, the purifying ability also decreases, so the secondary heat is bypassed from the intake system to the exhaust system, and the reaction heat generated by oxidizing HC and CO in the exhaust gas is generated. A secondary air supply device that raises the temperature of the three-way catalyst is also known in the art. In addition, if the exhaust gas containing CO ₂ gas, which has a larger heat capacity than N ₂ in the air, is mixed in the air-fuel mixture, the combustion temperature will be higher than that in the case where the exhaust gas is not mixed even if the same calorific value is burned. Generation of falling NOx can be suppressed. Therefore, exhaust gas recirculation (EGR: Exha
ust gas recirculation) is a known technique for reducing NOx.

[0003]

[Problems to be Solved by the Invention] Air Resour in California, USA
Law Proposed by ces Board On-Board DiagnosticSy
According to stem Phase II, it is obligatory to monitor the supply amount of the secondary air supply device and EGR supply device.
An object of the present invention is to realize a corresponding secondary air supply device and EGR supply device diagnostic device at low cost.

[0004]

According to the present invention, a shared portion is provided in the secondary air passage and the EGR passage, and a flow rate detecting means is provided in the shared portion. A means for providing a switching valve at the branch point between the secondary air passage and the EGR passage, or a means for providing a one-way valve after the air pump in the secondary air passage is provided.

[0005]

In the means using the switching valve, the secondary air passage and the EGR passage are switched to the passage in which the flow rate detecting means is installed, so that the signal of the flow rate detecting means is detected in each supply region, and each of them is detected. Make a diagnosis.

Further, in the means in which the one-way valve is provided after the air pump for the secondary air, the flow rate direction of the secondary air and the EGR
Since the flow directions of the amounts are opposite, the flow amount detected at each supply corresponds to the secondary air amount or the EGR amount.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block diagram of the present invention. An internal combustion engine, an intake system, an exhaust system, and an ignition device 19,
The fuel injection device 18 and the rotation speed detection means 17 are attached. An air cleaner and a first flow rate detecting means 11 are attached to the intake system, and an oxygen concentration detector 12 and a three-way catalyst 110 having a catalyst temperature detector are attached to the exhaust system. The internal combustion engine control device 10 uses the flow rate detecting means 1
Output signal Qa of 1 and output signal N of the rotation speed detecting means 17
e is taken in, the fuel injection amount Ti is calculated, and the injection amount of the fuel injection device is controlled. Further, the internal combustion engine control device 10 is
The air-fuel ratio feedback that corrects the fuel injection amount Ti so that the air-fuel ratio in the internal combustion engine becomes the stoichiometric air-fuel ratio from the signal of the oxygen concentration detection means 12 that detects the oxygen concentration in the exhaust gas. Take control.

The three-way catalyst 110 contains HC in exhaust gas,
Although it has an effect of purifying CO, it has a characteristic that its purifying ability becomes low at low temperatures. In this case, the secondary air supply device bypasses the internal combustion engine from the intake system to supply secondary air to the exhaust system to accelerate the oxidation reaction of HC and CO and accelerate the rise of the catalyst temperature. Further, for example, in a predetermined open loop state in which air-fuel ratio feedback control is not performed, such as during acceleration, the fuel injection amount may be increased to obtain a rich state in order to obtain high output. In this case, the HC in the exhaust gas,
Since the amount of CO is particularly large, the secondary air is supplied to purify the exhaust gas in the exhaust system to assist the purifying action of the three-way catalyst.

A second flow rate detecting means 15 and an air pump 13 are attached to the secondary air passage 111. The secondary air supply amount O ₂ can be directly detected by the flow rate detecting means 15, and the internal combustion engine control device outputs a signal for operating the secondary air supply device. However, when the detected secondary air amount O ₂ is smaller than a predetermined value despite the output of the signal for operating the secondary air supply device from the internal combustion engine control device, or the internal combustion engine control When the amount of secondary air to be controlled by the device is not supplied, it is determined that an abnormality has occurred in the secondary air supply device, and a signal is sent to a warning light or the like to prompt the driver for inspection and repair.

A second flow rate detecting means 15 is attached to the EGR passage 112. The EGR supply amount Q ₃ can be directly detected by the flow rate detecting means 15, and the internal combustion engine control device
Outputs a signal to activate the EGR feeder. However, when the detected EGR amount Q ₃ is smaller than a predetermined value, or the internal combustion engine control device controls, although the internal combustion engine control device outputs a signal for operating the EGR supply device. If the EGR amount is not supplied,
It is determined that an abnormality has occurred in the EGR supply device, and a signal is sent to a warning light or the like to prompt the driver to inspect or repair.

The above is the secondary air diagnosis and the EGR diagnosis, but it is a feature of the present invention that the flow rate detecting means for the secondary air diagnosis and the flow rate detecting means for the EGR diagnosis are both used here. That is, the flow rates O ₂ and Q ₃ are detected by the same flow rate detecting means.
Therefore, the secondary air passage 111 and the EGR passage 112 are shared via the switching valve 14, and the flow rate detecting means 15 is installed in the shared passage. The switching valve 14 is controlled by a signal from the internal combustion engine controller, and operates when each diagnostic condition is satisfied. Therefore, the secondary air diagnosis and the EGR diagnosis cannot be performed at the same time, but the cost is reduced.

A flow chart for realizing the above processing is shown in FIG. First, in step 20, it is determined from the internal state of the internal combustion engine control device whether or not it is in the secondary air supply region. If it is the secondary air supply region, the switching valve 14 is switched to the secondary air passage 111 in step 21. Then, from step 22, the internal combustion engine control device 1 is _{operated so} that the amount of secondary air O _2OUT to be supplied _{becomes equal} to the stoichiometric air-fuel ratio after the secondary air.
Calculate with 0. In step 23, the secondary air amount O _2OUT
The air pump 13 is operated so that Step two
In step 4, the signal O _{2in of} the second flow rate detecting means 15 is compared with the secondary air amount O _2OUT calculated in step 22, and if the difference is within a predetermined value ΔO ₂ , it is diagnosed as normal. Then, the process ends. If the difference exceeds the predetermined value ΔO ₂ in the comparison in step 24, the secondary air supply device is diagnosed as abnormal in step 25, and a signal is sent to a warning light or the like, or the comparison result in step 24 is displayed. This is recorded in the internal combustion engine controller 10.

Next, when it is determined in step 26 that the EGR supply region is set, in step 27, the switching valve 1
At 4 the EGR passage 112 is switched. Then, in step 28, the EGR amount Q _3out to be supplied is calculated. Then, in step 29, a signal is sent from the internal combustion engine control device 10 to the EGR valve 16 so that the EGR amount becomes Q _3out . In step 210, the signal Q _{3in of} the second flow rate detecting means 15
And the EGR amount Q _3out calculated in step 27 are compared,
If the difference is within a predetermined value ΔQ ₃ , it is diagnosed as normal and the process is terminated. If the difference exceeds the predetermined value ΔQ ₃ in the comparison in step 210, the EGR supply device is diagnosed as abnormal in step 211,
A signal is sent to a warning light or the like, and the comparison result in step 210 is recorded in the internal combustion engine controller 10.

In the above flow chart, the internal combustion engine controller 10 sends a signal to the switching valve 14 to make a diagnosis during each supply region, but the flow direction of the secondary air and the flow direction of the EGR are opposite. Because there is
By providing a valve that allows the secondary air to flow only in one direction after the air pump 13, the secondary air and EGR can be diagnosed by one flow rate detecting means without a switching valve. The block diagram is shown in FIG. The difference from FIG. 1 is that there is no switching valve and that a valve 31 that allows only one-way flow is attached after the air pump 13 for secondary air.

FIG. 4 shows a flow chart for realizing the processing of FIG. First, in step 40, it is determined from the internal state of the internal combustion engine control device whether or not it is in the secondary air supply region. If it is in the secondary air supply region, in step 41, the amount of secondary air to be supplied O _2OUT is calculated by the internal combustion engine controller so that the air-fuel ratio after the secondary air becomes the stoichiometric air-fuel ratio. At step 42, the air pump 1 is _{adjusted so} that the secondary air amount becomes O _2OUT.
Activate 3. In step 43, the signal O _{2in of} the second flow rate detecting means 15 is compared with the secondary air amount O _2OUT calculated in step 41, and the difference is a predetermined value ΔO.
If it is within ₂ , it is diagnosed as normal and the process ends. In the comparison in step 43, the difference is a predetermined value ΔO
If it exceeds ₂ was diagnosed as abnormal at step 44 the secondary air supply system, or send a signal to a warning lamp or the like Step 43
The result of the comparison is recorded in the internal combustion engine controller 10.

Next, if it is determined in step 45 that the EGR supply region is set, in step 46, the EGR amount Q to be supplied
Calculate _3out . Then, in step 47, the EGR amount Q
_A signal is sent from the internal combustion engine controller to the EGR valve 16 so that the _output becomes 3 out. In step 48, the signal Q _{3in of} the second flow rate detecting means and the EGR amount Q _3out calculated in step 27
Are compared, and if the difference is within a predetermined value ΔQ ₃ , it is diagnosed as normal and the process is terminated. Step 48
If the difference exceeds a predetermined value ΔQ ₃ in the comparison of the above, the EGR supply device is diagnosed as abnormal in step 49, a signal is sent to a warning light or the like, or the comparison result in step 48 is controlled by the internal combustion engine. Record in device 10.

[0017]

As described above, the secondary air supply device for the vehicle and the E
The GR supply device can be diagnosed by one flow rate detecting means, and an inexpensive diagnostic device can be configured.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a flowchart of the present invention.

FIG. 3 is another configuration diagram of the present invention.

FIG. 4 is another flowchart of the present invention.

[Explanation of symbols]

10 ... Internal-combustion engine control device, 11 ... First flow rate detecting means,
12 ... Oxygen concentration detecting means, 13 ... Air pump, 14 ...
Switching valve, 15 ... Second flow rate detecting means, 16 ... E
GR valve, 17 ... Rotation speed detecting means, 18 ... Fuel injection device, 19 ... Ignition device, 20, 40 ... Determination of secondary air supply region, 21 ... Switching valve operation, 22, 41 ... Secondary air amount calculation, 23 , 42 ... Air pump operation, 24, 43
... secondary air amount determination, 25, 44 ... secondary air supply device abnormality processing, 26, 45 ... EGR supply region determination, 27 ... switching valve operation, 28, 46 ... EGR amount calculation, 29,
47 ... EGR valve actuation, 31 ... One-way valve, 48, 21
0 ... EGR amount determination, 49, 211 ... EGR supply device abnormality processing, 110 ... Three-way catalyst, 111 ... Secondary air passage, 1
12 ... EGR passage.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 25/07 550 R 580 Z FG 01M 15/00 Z

Claims (6)

[Claims] 1. A secondary air supply device attached to an exhaust system of an internal combustion engine and an EGR device for recirculating exhaust gas of an internal combustion engine to an intake system, wherein a shared portion is provided in the secondary air passage and the EGR passage. Internal combustion engine. 2. The internal combustion engine according to claim 1, wherein a flow rate detecting means is provided in the common portion. 3. A secondary air supply device attached to an exhaust system of an internal combustion engine according to claim 1, wherein an internal combustion engine control device for calculating a target value of the secondary air supply amount and the secondary air supply amount A secondary air supply device that has a measuring unit and determines that the secondary air supply device has an abnormality when a difference between the target supply amount and a supply amount measurement value by the measuring unit is larger than a predetermined value. Diagnostic device for air supply device. 4. An EGR device that recirculates exhaust gas of an internal combustion engine to an intake system according to claim 1 or 2, and an internal combustion engine device that calculates a target value of an EGR amount or an EGR rate and an EGR amount or EGR rate measuring means. And the target EGR amount or E
A diagnostic device for an EGR device, characterized in that when the difference between the GR ratio and the EGR amount or EGR ratio measured value by the measuring means is larger than a predetermined value, it is determined that the EGR device is abnormal. 5. A secondary air passage and an EG according to claim 3 or 4.
A secondary air and EGR diagnostic device, characterized in that the R air passage is switched to a shared portion by a switching valve so that the secondary air amount and the EGR amount are detected by a flow rate detection means attached to the shared portion. 6. A one-way valve is provided after the air pump in the secondary air passage because the direction of the fluid flowing through the secondary air passage and the direction of the fluid flowing through the EGR passage are opposite to each other. A secondary air and EGR diagnostic device, which is capable of detecting the amount of secondary air and the amount of EGR with a flow rate detection means attached to a common portion without providing a switching valve.