JP2003314262A - Opening/closing valve for secondary air supply passage and failure diagnosis device for secondary air supply system using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an opening/closing valve for a secondary air supply passage with a constitution capable of accurate detection regarding a small open failure, and a failure diagnosis device for a secondary air supply system using the same. <P>SOLUTION: The secondary air supply system supplies secondary air via the secondary air supply passage continuous to the upstream side from an exhaust gas purifying device to be arranged in an exhaust route of an internal combustion engine. The opening/closing valve 13 switches an opening/closing condition of the secondary air supply passage on the upstream side from a check valve 134 to be arranged in the secondary air supply passage, and is provided with a conducting passage 137 to conduct pressure in an air chamber 130b on the upstream side of a valve body 133 to a pressure sensor 15. The conducting passage 137 is provided on the side opposing to an entrance port 136 on the side face of the air chamber 130b. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-off valve used in a secondary air supply system for supplying secondary air to the upstream side of an exhaust purification device arranged in an exhaust system of an internal combustion engine, and a secondary valve using the same. The present invention relates to a failure diagnosis device for an air supply system.

[0002]

2. Description of the Related Art As an exhaust gas purifying apparatus for an internal combustion engine, a three-way catalyst is arranged in an exhaust system so that CO, HC and NOx contained in exhaust gas can be obtained.
A device for reducing components to purify is known. Further, by feeding air from the air pump to the secondary air supply passage having an opening / closing valve connected to the exhaust pipe, the secondary air is supplied into the exhaust pipe to increase the oxygen concentration, and HC in the exhaust gas, There is known a technique of promoting purification of exhaust gas by oxidizing CO.

In such a secondary air supply system, if an abnormality occurs in a component such as an air pump or an on-off valve, exhaust gas purification efficiency is lowered and emission is deteriorated. Therefore, the abnormality is judged early. There is a need. Therefore, as a technique for detecting this type of abnormality, the techniques disclosed in Japanese Patent Application Laid-Open Nos. 9-21312 and 9-125945 are known.

In the former, a pressure sensor is arranged between the air pump and the opening / closing valve in the secondary air supply passage to detect an abnormality in the secondary air supply device based on the detected pressure value. In the latter, a pressure sensor is arranged in the secondary air supply passage, and an abnormality of the secondary air supply device is detected based on the difference between the maximum value and the minimum value of the detected pressure pulsation.

[0005]

When the pressure sensor is arranged between the air pump and the opening / closing valve as described above, a large open failure such as the opening / closing valve not being closed even when the opening / closing valve is fully opened is easy to detect. In the case of a small opening failure such that a relatively small foreign object is caught in the valve body of the on-off valve, it is difficult to detect. This is because the pressure difference from the normal state (closed) is small in the small opening failure. If the threshold value is decreased to determine such a small opening failure, the opening / closing valve may be changed depending on the change in the discharge pressure of the air pump. This is because there is a risk that the on-off valve may be erroneously determined to be abnormal even though the above is normal.

Therefore, the present invention aims to provide a secondary air supply passage opening / closing valve having a configuration capable of accurately detecting such a small open failure and a failure diagnosing device for a secondary air supply system using the same. And

[0007]

In order to solve the above-mentioned problems, a secondary air supply passage opening / closing valve according to the present invention is a secondary air supply connected upstream from an exhaust gas purification device arranged in an exhaust path of an internal combustion engine. In the secondary air supply system for supplying the secondary air through the passage, the secondary air supply passage that switches the open / closed state of the secondary air supply passage on the upstream side of the check valve arranged in the secondary air supply passage. In the on-off valve, the on-off valve body is provided with a communication path that opens into the upstream chamber of the valve body and communicates with the pressure sensor, separately from the inlet port.

A failure diagnosis apparatus for a secondary air supply system according to the present invention comprises a secondary air supply passage opening / closing valve according to the present invention,
A failure diagnosing device for a secondary air supply system, comprising a pressure sensor connected to the communication path, an air pump arranged upstream of the opening / closing valve, and a check valve arranged downstream of the opening / closing valve. An abnormality detection unit for detecting an abnormality of the on-off valve based on the pressure pulsation detected when the air pump is stopped is provided.

In the case of a small opening abnormality in which a small foreign matter is caught in the valve body of the on-off valve, the pressure inside the upstream chamber near the valve body is
Due to the conduction between the upstream side and the downstream side, it is affected by the exhaust pulsation on the downstream side, but this pulsation is attenuated as it moves away from the valve body, so it was difficult to detect it outside the on-off valve. Since the on-off valve according to the present invention is capable of detecting this pressure pulsation by providing a communication path from the upstream chamber to the pressure sensor separately from the inlet port, the small opening which has been difficult to detect in the past. Even in the case of abnormality, it can be accurately detected. Further, it is possible to judge the abnormal level of valve opening depending on the magnitude of pulsation.

It is preferable that the communication passage is opened in the upstream chamber at a position substantially opposite to the inlet port across the valve body. By opening the communication path at a position away from the flow path from the inlet port of the opening / closing valve to the valve body, pressure detection independent of the flow in the upstream chamber is possible, and accurate determination is possible.

It is preferable that the conduction path extends upward from the horizontal direction from the opening / closing valve body in the mounted state of the opening / closing valve. With this configuration, it is possible to suppress the infiltration of the condensed water into the conduction path and to easily discharge the condensed water when it intrudes, so that it is possible to suppress the freezing of the condensed water in the conduction path when the engine is stopped during cold weather. Therefore, it is possible to effectively prevent erroneous determination.

[0012] It is preferable that the leading end of this conduction path is arranged so as to project toward the vicinity of the valve body. As a result, smaller pulsations can be detected, and the abnormal level that can be determined can be expanded.

When the check valve is further integrated, the system can be easily assembled and the individual difference in pressure pulsation is reduced, so that the detection accuracy can be improved.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same constituent elements in each drawing as much as possible in the drawings, and redundant description will be omitted.

FIG. 1 is a schematic configuration diagram of a secondary air supply system including a secondary air supply passage opening / closing valve according to the present invention. FIG. 2 is a first secondary air supply passage opening / closing valve according to the present invention. It is sectional drawing which shows the embodiment.

The secondary air supply device (hereinafter referred to as AI supply device) 1 is attached to a multi-cylinder gasoline engine (hereinafter simply referred to as engine) 2 which is an internal combustion engine. Here, an intake pipe 20 and an exhaust pipe 21 are connected to the engine 2, and a throttle 24 is arranged on the intake pipe 20 and connected to an intake filter 25. On the other hand, an exhaust gas purification device 22 including a three-way catalyst is arranged downstream of the exhaust pipe 21.

The AI supply device 1 includes a secondary air (AI) supply passage that connects the position of the intake pipe 20 between the intake filter 25 and the throttle 24 and the exhaust pipe 21 between the engine 2 and the exhaust purification device 22. 11 is provided with an electric motor driven air pump (AP) 12 on the AI supply passage 11.
Is arranged, and a secondary air supply passage opening / closing valve (hereinafter, referred to as an opening / closing valve at the end) 13 according to the present invention is arranged downstream thereof. A pressure sensor 15 is connected to the on-off valve 13. The opening / closing valve 13 includes a throttle 24 of the intake pipe 20.
A pipe 16 extending from the downstream is connected, and this pipe 1
6 is further provided with an electromagnetic three-way valve 17 (for convenience of explanation, the pipe 16 is divided into two parts by the three-way valve 17 portion, the intake pipe 20 side is indicated by reference numeral 16a, and the on-off valve 13 side is indicated by reference numeral 16b). . The three-way valve 17 is connected to the outside air via a passage 18 and an air filter 19.

Here, the on-off valve 13 is an integrated check valve, and the inside of the main body 130 is divided into four air chambers 130a to 130d, as shown in FIG. The diaphragm 13 is provided between the air chambers 130a and 130b.
1, the valve body 133 is arranged in the connection hole portion of the air chamber 130b with the air chamber 130c, and the reed valve body 134 serving as a check valve is arranged in the connection hole portion of the air chamber 130d with the air chamber 130c. The valve body 133 is directly connected to the diaphragm 131 by a rod 133a. The reed valve body 134 includes a leaf spring portion 134a and a valve body 134b, and the leaf spring portion 134a presses the valve body 134b against the valve seat portion of the body 130 with a predetermined force.

The air chamber 130a is connected to the pipe 16b through a connection port 135, and inside thereof, a spring 132 for pressing the diaphragm 131 toward the air chamber 130b is arranged. An inlet port 136 is provided on the side surface of the air chamber 130b and is connected to the AI supply passage 11 connected to the AP 12. Then, a conduction path 137 is provided on the side surface facing this, and the pressure sensor 15 is attached via a tube 138. Tube 138
Is installed so as to bend upward from the horizontal when mounted on a vehicle. An outlet port 139 is provided at the lower end of the air chamber 130d and is connected to the AI supply passage 11 connected to the exhaust pipe 21.

The control device 10 for controlling the operation of the AI supply device 1 is electrically connected to the engine ECU 23 for controlling the engine so as to exchange information with each other, and receives the output signal of the pressure sensor 15. With
The motor drive of the AP 12 and the opening / closing of the three-way valve 17 are controlled.
This control device also serves as the abnormality detection unit of the failure diagnosis device for the secondary air supply system according to the present invention. The controller 1
0 may form a part of the engine ECU 23.

This AI supply device 1 has a high fuel concentration mainly during cold start, a small air-fuel ratio (A / F), and the exhaust purification device 22 does not have a sufficiently high temperature and thus its function is improved. In a state where the control device 10 is not sufficiently exerted, the control device 10 drives the air pump 12, and the three-way valve 17 connects the pipe 16a and the pipe 16b to guide the negative pressure in the intake pipe 20 to the air chamber 130a of the on-off valve 13. . On-off valve 1
3, the pressure on the air chamber 130b side is
The pressure becomes higher than the pressure on the side a, and the diaphragm 131 moves to the side of the air chamber 130a.
33 moves upward in FIG. 2 and moves into the air chambers 130b and 13b.
Connect with 0c. Further, since the exhaust pipe 21 side also has a negative pressure, the pressure on the air chamber 130c side becomes higher than the pressure on the air chamber 130d side, so that the reed valve element 134 is moved to the air chamber 13 side.
The air chambers 130c and 130d are communicated with each other by being pushed out toward the 0d side. As a result, part of the air that has passed through the intake filter 25 (secondary air) is guided into the exhaust pipe 21 through the AI supply passage 11. As a result, the oxygen concentration in the exhaust gas is increased, the A / F thereof is increased, secondary combustion of HC and CO in the exhaust gas in the exhaust pipe 21 is promoted to purify the exhaust gas, and the exhaust gas temperature is increased. Thus, the temperature rise of the exhaust gas purification device (three-way catalyst) 22 is promoted to suppress the deterioration of emission.

When the AI supply is stopped, the control unit 10
P12 is stopped and the on-off valve 13 is closed. Specifically, by controlling the three-way valve 17 so that the passage 18 and the pipe 16b communicate with each other, outside air is introduced into the air chamber 130a of the on-off valve 13 through the air filter 19, the passage 18, and the pipe 16b, and the air The pressure in the chamber 130a is set to atmospheric pressure, and the spring 132 presses the valve body 133 against the valve seat of the main body 130 to cut off the communication between the air chambers 130b and 130c.

The AI supply device 1 has a function of detecting abnormalities of the constituent parts, that is, the AP 12, the opening / closing valve 13 and the like by using the pressure behavior detected by the pressure sensor 15.
Specifically, first, when the AI system is stopped, that is, AP12
The pressure sensor 15 with the on-off valve 13 closed.
The pulsation amount of the pressure value P is detected by. FIG. 3 is a graph showing this pulsation. Hereinafter, it is assumed that the AP 12 is operating as controlled.

The valve body 133 of the on-off valve 13 has an air chamber 130b.
If the communication between the and 130c is completely cut off, the pressure detected by the pressure sensor 15 should be almost atmospheric pressure. On the other hand, as shown in FIG. 2, when the foreign material 14 exists between the valve body 133 and the valve seat, so-called biting occurs, the air chamber 130b and the air chamber 130c communicate with each other. The pulsation in the exhaust pipe 21 is transmitted. If the reed valve body 134 is functioning normally, the exhaust pipe 21
On the side, that is, when the pressure in the air chamber 130d is higher than that in the air chamber 130c, the communication between the air chambers 130c and 130d is cut off, so that the pressure sensor 15 is detected depending on the size of the foreign matter 14.
The pressure value P detected in 1 pulsates as shown in FIG.

Further, when the reed valve body 134 fails and an open failure occurs in which the air chambers 130c and 130d are always in communication with each other, the pulsation in the exhaust pipe 21 is transmitted to the air chamber 130b. Pressure value P detected at 15
Pulsates as shown in FIG. In this way, the abnormality of the valve body 133 and the reed valve body 134 can be determined from the pulsating state of the pressure value P. In particular, it is possible to accurately determine the clogging of a small foreign matter, which has been difficult to discriminate in the past, and also to estimate the degree of abnormal opening, that is, the size of the foreign matter depending on the magnitude of the pulsation.

The pulsation in the exhaust pipe 21 is attenuated as it moves away from the exhaust pipe 21. Since the on-off valve 13 according to the present invention measures the pressure with the pressure sensor 15 by directly drawing out the conduit 137 from the air chamber 130b portion, when detecting the pressure in the pipe 11 on the upstream side of the on-off valve 13. Compared to,
The pressure can be measured while the pulsation width is large, and the pulsation can be detected with high accuracy. In particular, accurate detection is possible by taking out the pressure from the side facing the inlet port 136 across the valve body 133. Further, when the vehicle is mounted on a vehicle, the conduit 137 leading to the pressure sensor 15 and the tube 138 are arranged so as to face upward from the horizontal direction, so that condensed water enters the conduit 137 and the tube 138 from the exhaust pipe 21 side. Even if it facilitates its discharge,
Accurate measurement can be performed by preventing freezing when the engine 2 is stopped.

4 to 6 are configuration diagrams showing the second to fourth embodiments of the on-off valve 13 according to the present invention, respectively. Each of the embodiments has the same basic configuration as that of the first embodiment shown in FIG.
Only the configuration of 8 is different.

In the second embodiment shown in FIG. 4, the conducting path 137 itself is formed so as to extend obliquely upward instead of horizontally when mounted on a vehicle, and the tube 138.
By providing the taper portion 137a at the connecting portion to, the invasion of the condensed water into the conduction path 137 is suppressed, and even if it intrudes, the condensate can be easily discharged.

In the third embodiment shown in FIG. 5, the conducting path 137 is formed in an L shape and is connected to the tube 138 at an upwardly extending portion. Also in this embodiment, similarly to the second embodiment, the tapered portion 137a is provided at the connecting portion to the tube 138. This makes it difficult for condensed water to collect in the joint between the conducting path 137 and the tube 138, and facilitates discharge of the condensed water if it should enter.

In the fourth embodiment shown in FIG. 6, the second
The conducting path 137 in the above embodiment is extended into the air chamber 130b, and its tip 137b is arranged in the vicinity of the valve body 133. With such an arrangement, the pressure pulsation in the vicinity of the valve body 133 can be grasped, so that it becomes possible to detect even the minute foreign matter being caught.

As shown in FIG. 7, the on-off valve 13
The upstream valve may be a solenoid valve instead of the diaphragm type. In this case, when the valve body 133 is arranged in the air chamber 130b portion and opened when moving upward in the figure, when the valve body 133 is arranged in the air chamber 130c portion and moving downward. It may be configured to open to.
Further, the check valve may be provided separately from the on-off valve 13 instead of being integrated.

[0032]

As described above, according to the present invention, 2
Since it is possible to more accurately measure the pressure in the air chamber upstream of the valve body of the opening / closing valve that is the opening / closing means in the next air supply system,
On the basis of the pressure pulsation of this portion when the air pump is stopped and the opening / closing valve is controlled, it is possible to accurately detect an abnormality that is difficult to distinguish in the past, such as clogging of the valve body with foreign matter.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a secondary air supply system including a secondary air supply passage opening / closing valve according to the present invention.

FIG. 2 is a sectional view showing a first embodiment of a secondary air supply passage opening / closing valve according to the present invention.

FIG. 3 is a graph showing pressure pulsation used in abnormality detection.

FIG. 4 is a cross-sectional view showing a second embodiment of a secondary air supply passage opening / closing valve according to the present invention.

FIG. 5 is a sectional view showing a third embodiment of a secondary air supply passage opening / closing valve according to the present invention.

FIG. 6 is a sectional view showing a fourth embodiment of a secondary air supply passage opening / closing valve according to the present invention.

FIG. 7 is a sectional view showing a fifth embodiment of a secondary air supply passage opening / closing valve according to the present invention.

[Explanation of symbols]

1 ... Secondary air supply device, 2 ... Engine, 10 ... Control device, 11 ... Secondary air supply passageway, 12 ... Air pump, 13
... Secondary air supply passage open / close valve, 14 ... Foreign matter, 15 ... Pressure sensor, 16 ... Piping, 17 ... Three-way valve, 18 ... Passage, 19 ...
Air filter, 20 ... Intake pipe, 21 ... Exhaust pipe, 22 ... Exhaust gas purification device, 23 ... Engine ECU, 24 ... Throttle, 25 ... Intake filter, 130 ... Main body, 130a-1.
30d ... Air chamber, 131 ... Diaphragm, 132 ... Spring, 133 ... Valve body, 134 ... Reed valve body, 135 ...
Connection port, 136 ... Inlet port, 137 ... Conducting path, 1
38 ... Tube, 139 ... Exit port.

Continued front page    F-term (reference) 3G091 AA17 AA28 AB03 BA14 BA15                       BA19 BA29 BA31 CA13 CA22                       CB02 DA01 DA02 DB10 EA00                       FB10 FB11 FB12 GA06

Claims (6)

[Claims] 1. A secondary air supply passage connected upstream from an exhaust gas purification device arranged in an exhaust path of an internal combustion engine.
A secondary air supply passage opening / closing valve for switching the opening / closing state of the secondary air supply passage upstream of a check valve arranged in the secondary air supply passage in a secondary air supply system for supplying secondary air. The on-off valve main body is a secondary air supply passage on-off valve that has a communication path that opens into the upstream chamber of the valve body and communicates with the pressure sensor separately from the inlet port. 2. The secondary air supply passage opening / closing valve according to claim 1, wherein the communication passage opens in the upstream chamber at a position substantially opposite to the inlet port across the valve body. 3. The secondary air supply passage opening / closing valve according to claim 1, wherein the conduction path extends upward from the opening / closing valve main body in a mounted state of the opening / closing valve. 4. The secondary air supply passage opening / closing valve according to claim 2, wherein the leading end of the communication passage is arranged so as to project toward the vicinity of the valve body. 5. The secondary air supply passage opening / closing valve according to claim 1, wherein the check valve is further integrated. 6. The secondary air supply passage opening / closing valve according to claim 1, a pressure sensor connected to the communication passage, an air pump arranged upstream of the opening / closing valve, and the opening / closing. A failure diagnosing device for a secondary air supply system comprising a check valve arranged downstream of a valve, wherein the device is based on a pressure pulsation detected by the pressure sensor when the air pump is stopped and the on-off valve is closed. Equipped with an abnormality detection unit that detects an abnormality in the on-off valve 2
Failure diagnosis device for secondary air supply system.