JPS63259150A - Exhaust gas recirculation equipment for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent an exhaust gas recirculation from being continued under a disordered control characteristic by forcing an exhaust gas recirculation control valve to open to stop the exhaust gas recirculation control when a failure in an exhaust gas recirculation equipment is discovered diagnostically. CONSTITUTION:In an exhaust-gas recirculation control valve 20, an inlet port 21 is connected by means of a conduit tube 12 to an exhaust gas intake port, and then, an outlet port 22 is connected by means of a conduit tube 13 to an exhaust gas injection port 11 respectively. In addition, a diaphragm chamber 27 is connected through a vacuum control valve 30 for controlling the back pressure, an electromagnetic change-over valve 32 and the like to an intake-pipe vacuum takeoff port 34. In this case, each of the detection signals from various sensors 56, 57, 59 for detecting the operating condition of an internal combustion engine 1 is inputted to a microcomputer 50 respectively. And further, the microcomputer 50 is used to diagnose a failure in an exhaust gas recirculation equipment. Consequently, when a failure is discovered diagnostically, the electromagnetic change-over valve 32 is electrified, and a port (a) is connected to a port (c) so that the atmospheric pressure is introduced into the diaphragm chamber 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an exhaust gas recirculation device for an internal combustion engine used in vehicles such as automobiles, and in particular to diagnosis of whether the exhaust gas recirculation device is operating normally. The present invention relates to an exhaust gas recirculation system equipped with a failure diagnosis device that performs.

2. Description of the Related Art Exhaust gas recirculation devices incorporated in internal combustion engines used in vehicles such as automobiles generally include an exhaust gas recirculation control valve for controlling the flow rate of exhaust gas recirculation, a negative pressure control valve for controlling back pressure,
It contains temperature-sensitive valves, etc., and if a failure occurs in these components, exhaust gas recirculation will no longer occur and the N in the exhaust gas will be reduced.
There is a possibility that the internal combustion engine will be operated in a state where Ox is not reduced. Even if exhaust gas recirculation is no longer performed due to a malfunction, the internal combustion engine will continue to operate without any problems, so there is a risk that the driver will continue to operate the engine for a long period of time without realizing this, resulting in air pollution. arise. Furthermore, if exhaust gas recirculation is not performed within a predetermined operating range, knocking may occur, and fuel efficiency may deteriorate due to pump loss due to the intake air of the internal combustion engine itself.

In view of the above-mentioned problems, a failure alarm system has already been proposed that is configured to notify the user of this and provide an incentive for repairs when exhaust gas recirculation is not performed due to a failure of the exhaust gas recirculation system. This is shown, for example, in Utility Model Publication No. 52-9471 and Utility Model Application Publication No. 1987-67220, and also in Utility Model Application No. 163288-1980, filed by the same applicant as the present applicant. It is also proposed.

Problems to be Solved by the Invention Conventionally, even if the exhaust gas recirculation system has been diagnosed for failure, the driver is only notified of this by means of an indicator lamp, etc.; Because no special operation stop command is given to the circulation system, there is a possibility that exhaust gas recirculation will be performed with abnormal control characteristics, and if the cause of the failure is a stick in the exhaust gas recirculation control valve, the continued operation may not be possible. As a result, the lock position of the exhaust gas recirculation control valve shifts to the valve open side, which may further worsen the failure condition.

It is an object of the present invention to provide an improved exhaust gas recirculation device that solves the above-mentioned problems.

Means for Solving the Problems According to the present invention, the above objects include exhaust gas recirculation passage means for guiding exhaust gas to an intake passage, and controlling the flow rate of exhaust gas flowing through said exhaust gas recirculation passage means. an exhaust gas recirculation control valve for diagnosing whether or not the exhaust gas recirculation control valve is operating normally; and a failure diagnosis means for diagnosing whether or not the exhaust gas recirculation control valve is operating normally; This is achieved by an exhaust gas recirculation device having a forced stop means for forcibly stopping the engine, and a control means for operating the forced stop means when a failure is determined by the failure diagnosis means.

Effects and Effects of the Invention According to the above-described configuration, when diagnosing a failure of the exhaust gas recirculation device, the forced stop means is activated to open the exhaust gas recirculation control valve, thereby stopping the exhaust gas recirculation. It is avoided that the control is stopped and exhaust gas recirculation continues with abnormal control characteristics, and that the fault condition is also prevented from worsening.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail by way of embodiments with reference to the accompanying drawings.

FIG. 1 shows one embodiment of an exhaust gas recirculation device according to the invention. In the figure, 1 indicates an internal combustion engine, which includes an air cleaner 2, an air flow meter 3,
, air is drawn into the combustion chamber 7 through an intake pipe 5 having a throttle valve 4, and an intake manifold 6, and fuel is injected and supplied from a fuel injector 8, and burned gas,
That is, exhaust gas is discharged to the exhaust manifold 9.

The exhaust manifold 9 is provided with an exhaust gas intake port 10 for exhaust gas recirculation, and the intake manifold 6 is provided with an exhaust gas injection port 11. are connected to each other in communication by a conduit 12 for exhaust gas recirculation, an exhaust gas recirculation control valve 20 and a conduit 13.

The exhaust gas recirculation control valve 20 has an inlet port 21 and an outlet port 22, the inlet port 21 being connected in communication with the exhaust gas intake boat 10 by a conduit 12, and the outlet port 22 being connected in communication with the exhaust gas intake boat 10 by a conduit 13. It is communicatively connected to port 11.

The exhaust gas recirculation control valve 20 includes a valve boat 23 and a valve element 24.
The valve port 23 is opened and closed by a valve element 24 and the degree of opening thereof is controlled to control the exhaust gas recirculation flow rate. The valve element 24 is connected to a diaphragm 26 of a diaphragm device 25, and is pushed down by the spring force of a compression coil spring 28 to push the valve boat 23 when a negative pressure greater than a predetermined value, for example, −70 mmHg, is not introduced into the diaphragm chamber 27. When the diaphragm chamber 27 is closed and a negative pressure larger than a predetermined value is introduced into the diaphragm chamber 27, the valve boat 23 rises against the spring force of the compression coil spring 28 in response to the negative pressure and opens the valve boat 23.

The diaphragm chamber 27 of the exhaust gas recirculation control valve 20 is connected to a conduit 29, a negative pressure control valve 30 for controlling back pressure. It is connected to an intake pipe negative pressure outlet port 34 provided in the intake pipe 5 via a conduit 31, an electromagnetic switching valve 32, and a conduit 33. As shown, the intake pipe negative pressure outlet port 34 is located upstream of the throttle valve 4 when the throttle valve 4 is in the fully closed position, and is located upstream of the throttle valve 4 when the throttle valve 4 is opened beyond a relatively small predetermined opening. It is provided to be located on the downstream side.

The negative pressure control valve 30 has a valve element 36 that opens and closes the valve port 35 and a diaphragm 37 supporting the valve element. A chamber 38 and a diaphragm chamber 39 are defined on the lower side, and the diaphragm closes the valve by the action of a compression coil spring 40 when pressure (positive pressure) higher than a predetermined value is not introduced into the diaphragm chamber 39. Element 3
6 is separated from the valve boat 35 to open the valve boat, and when a pressure higher than a predetermined value is introduced into the diaphragm chamber 39, it moves upward in the figure against the action of the compression coil spring 40. Displacing the valve element 36 to the valve port 35
The valve port is located in a position where the valve port is closed by contacting the valve port.

The diaphragm chamber 39 of the negative pressure control valve 30 is connected by a conduit 41 to a pressure chamber 4 between the valve port 23 of the exhaust gas recirculation control valve 20 and an orifice 42 provided downstream therefrom.
3, and the exhaust gas pressure in the pressure chamber is introduced.

The structure consisting of the negative pressure control valve 30 and the orifice 42 as described above is a well-known back pressure control mechanism, and in the exhaust gas recirculation operating range where intake pipe negative pressure is applied to the exhaust gas recirculation control valve 2o. , adjust the negative pressure supplied to the diaphragm chamber 27 of the exhaust gas recirculation control valve 20 so as to keep the exhaust gas pressure in the pressure chamber 43 substantially constant; in other words, adjust the opening degree of the valve port 23; As a result, the ratio of the exhaust gas recirculation flow rate to the intake air flow rate, that is, the EGR rate, is kept almost constant at all times.

When the electromagnetic switching valve 45 is de-energized, the port a is connected to the port b and the diaphragm chamber 2 of the exhaust gas recirculation control valve 2o is connected.
7 is set in a state in which negative pressure can be introduced into the intake pipe, that is, in a state in which exhaust gas recirculation can be performed, and when energized, port a is connected to port C so that only atmospheric pressure is introduced into the diaphragm chamber 27, Exhaust gas recirculation is forced to stop.

According to the configuration described above, the electromagnetic switching valve 32 is not energized, and the exhaust gas recirculation control valve 20 has a negative pressure larger than a predetermined value, for example, negative pressure larger than -70 mmHg, acting on the two conduits. When the valve is open, the exhaust gas is recirculated at a flow rate corresponding to the valve amount.

In the figure, 50 indicates a microcomputer that performs fuel injection amount control and diagnosis of the exhaust gas recirculation system. The microcomputer 50 has a general structure and includes a central processing unit (CPU) 51, a memory 52, an input port 53, and an output port 54. The number sensor 56 receives information regarding the rotational speed of the internal combustion engine 1, the water temperature sensor 57 receives information regarding the temperature of the cooling water of the internal combustion engine 1, and the air flow meter 3 receives information regarding the intake air flow rate. Information regarding the temperature of the conduit 10 is provided by a temperature sensor 59 installed in each of the pipes 10 and 20. Based on this information, a diagnosis is made to determine whether the exhaust gas recirculation system is operating normally. When it is determined that the valve is not operating, the indicator lamp 58 is turned on and the solenoid switching valve 32 is turned on.
It is designed to energize.

Next, the operation of the exhaust gas recirculation device according to the present invention will be explained with reference to the flowchart shown in FIG.

The control routine shown in FIG. 2 is executed as an interrupt routine at predetermined time intervals, and in the first step 10,
A determination is made as to whether exhaust gas recirculation diagnosis conditions are met. It is determined whether the exhaust gas recirculation diagnosis condition is satisfied or not based on the intake air flow rate detected by the air flow meter 3, the rotation speed of the internal combustion engine 1 detected by the rotation speed sensor 56, and the water temperature sensor 587.
The step 20 is performed in accordance with the cooling water temperature of the internal combustion engine 1 detected by the step 20, and when the exhaust gas recirculation diagnosis condition is satisfied, the process proceeds to step 20.

In step 20, it is determined whether the exhaust gas recirculation passage temperature detected by the temperature sensor 59 is equal to or higher than a predetermined value, and exhaust gas recirculation diagnosis is executed. When the exhaust gas recirculation passage temperature is not above a predetermined value, it is determined that the exhaust gas recirculation system is malfunctioning, whereas when the exhaust gas recirculation passage temperature is above the predetermined value, the exhaust gas recirculation system is determined to be normal. It is determined that there is.

Note that this exhaust gas recirculation diagnosis may be performed in various ways other than depending on whether the exhaust gas recirculation passage temperature is equal to or higher than a predetermined value.

After step 20, proceed to step 30;
In this step, it is determined whether or not the exhaust gas recirculation device is determined to be malfunctioning. When a failure is determined, the process proceeds to step 50; otherwise, the process proceeds to step 40.

In step 40, the indicator lamp 58 is turned off and the electromagnetic switching valve 32 is turned off. At this time, the boat a of the electromagnetic switching valve 32 is the boat b.
By being connected to the diaphragm chamber 27 of the exhaust gas recirculation control valve 20, intake pipe negative pressure is introduced into the diaphragm chamber 27 of the exhaust gas recirculation control valve 20, and exhaust gas recirculation can be performed.

At step 50, indicator lamp 58 is illuminated and exhaust gas recirculation control valve 32 is energized to notify the driver that exhaust gas recirculation has failed. At this time, boat a of the electromagnetic switching valve 32 is connected to boat C, and negative pressure is no longer introduced into the diaphragm chamber 27 of the exhaust gas recirculation control valve 20, but atmospheric pressure is introduced, and the exhaust gas is recirculated. Circulation is forced to stop.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the exhaust gas recirculation device according to the present invention, and FIG. 2 is a flowchart showing the operation of the exhaust gas recirculation device according to the present invention. 1... Internal combustion engine, 2... Air cleaner, 3... Air flow meter, 4... Throttle valve, 5...
intake pipe. 6...Intake manifold, 7...Combustion chamber, 8...
Fuel injector, 9...Exhaust manifold, 10.
...Exhaust gas intake boat, 11...Exhaust gas injection boat, 12.13...Conduit, 20...Exhaust gas recirculation control valve. 21...Entrance boat, 22...Exit boat, 23.
... Valve boat, 24... Valve element, 25... Diaphragm device. 26...Diaphragm, 27...Diaphragm chamber,
28... Compression coil spring, 29... Conduit, 30...
・Negative pressure control valve, 31... Conduit, 32... Solenoid switching valve, 33... Conduit, 34... Intake pipe negative pressure take-out boat,
35... Valve boat, 36... Valve element, 37... Diaphragm, 38... Atmospheric release chamber, 39... Diaphragm chamber, 40... Compression coil spring, 41... Conduit, 42 ... Orifice, 43... Pressure chamber, 50...
- Microcomputer, 51...Central processing unit, 52...Memory, 53...Input board, 54...
・Output port, 55...Distributor, 56・
...Rotation speed sensor, 57...Water temperature sensor. 58...Indicator lamp, 59...Temperature sensor patent applicant: Toyota Motor Corporation representative
Patent Attorney Masatake Akashi Figure 2 (self-motivated) Procedural Amendment 1, Indication of Case 1985 Patent Application No. 093947 2
, Title of the invention: Exhaust gas recirculation device for internal combustion engines 3, Relationship with the case of the person making the amendment Patent applicant address: 1, Toyotacho, Toyotafu, Aichi Prefecture Name (3)
20)) Yota Jidosha Co., Ltd. 4, Agent address: 6-19-19 Shinkawa, Chuo-ku, Tokyo 104, Kumo 104, Number of inventions increased by amendment: 07, Subject of amendment: Drawing (self-initiated) Procedural amendment band 1982 July 20, 2015 1, Incident Indication 1988 Patent Application No. 093947 2
, Title of the invention: Exhaust gas recirculation device for internal combustion engines 3, Relationship with the case of the person making the amendment Patent applicant address: 1, Toyotacho, Toyotafu, Aichi Prefecture Name (3)
20')) - Yota Jidosha Co., Ltd. 4, Agent residence ato 4 1-5-19-6 Shinkawa, Chuo-ku, Tokyo, Number of inventions increased by amendment 07, Subject of amendment Specification

Claims (1)

[Claims] exhaust gas recirculation passage means for guiding exhaust gas to the intake passage;
an exhaust gas recirculation control valve for controlling the flow rate of exhaust gas flowing through the exhaust gas recirculation passage means; a failure diagnosis means for diagnosing whether the exhaust gas recirculation control valve is operating normally; A forced stop means for forcibly stopping exhaust gas recirculation by prohibiting operation of a gas recirculation control valve, and a control means for operating the forced stop means when a failure is determined by the failure diagnosis means. Exhaust gas recirculation device.