JP2001329916A - Egr valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress intrusion of water, foreign matters and the like into a breathing passage and to prevent the water, foreign matters and the like from reaching a pressure receiving body storing part even if they intrude into the breathing passage, without increasing the number of part items. SOLUTION: A valve case 13 is provided on an EGR pipe 12 to communicatingly connect an exhaust passage and an inlet passage by bypassing an engine, a valve body 14 to get communication with or interrupt the EGR pipe is stored in the EGR pipe so that it can be reciprocated. A pressure receiving body 16 is linked to the valve body, and a pressure receiving body storing part 13a is formed in the valve case. The pressure receiving body storing part is partitioned to a first chamber 13d and a second chamber 13e, the first chamber is in communication with an air supplying and exhausting means 24, and the second chamber is in communication with the atmosphere through a breathing passage 26. The hole diameter of the breathing passage at one of its both ends in communication with the atmosphere is formed small, and the breathing passage is formed into a maze shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EGR pipe for bypassing an engine, which is opened and closed according to the operating condition of the engine, and a part of the exhaust gas of the engine is returned to an intake system to reduce NOx.
The present invention relates to an EGR valve for reducing the emission of exhaust gas.

[0002]

2. Description of the Related Art Conventionally, as this type of EGR valve, as shown in FIGS. 6 and 7, a valve is mounted on a timing gear case 5 in which a timing gear (a gear for driving a camshaft, a fuel injection pump, etc.) is housed. A case 3 is mounted, a valve body 4 is reciprocally accommodated in the valve case 3, and a piston accommodating portion 3 a for slidably accommodating a piston 6 connected to the valve body 4 is formed in the valve case 3. Are known. In the EGR valve 1, a through hole 3 b communicating with the EGR pipe 2 is formed in the valve case 3.
A valve seat 3c that can shut off the GR pipe 2 is formed (FIG. 6).

The piston housing 3a is partitioned by a piston 6 into a first chamber 3d and a second chamber 3e. The first chamber 3d communicates with an air supply / discharge means 8 (FIG. 6), and the second chamber 3e is a breathing passage. 7 to the atmosphere (FIGS. 6 and 7). The air supply / discharge means 8 includes an air tank in which compressed air is stored, and a switching valve provided in an air pipe 8a that connects the air tank and the first chamber 3d (FIG. 6). Reference numeral 9 in FIG. 6 denotes a compression coil spring that biases the piston 6 in a direction in which the valve body 4 is seated on the valve seat 3c. Further, the breathing passage 7 is formed on a surface of the valve case 3 facing the timing gear case 5, a first recess 7a, a second recess 7b formed on the timing gear case 5 so as to face the first recess 7a, and a first recess. A through-hole 7c is formed in the bottom surface of 7a so as to communicate with the second chamber 3e (FIGS. 6 and 7).

In the EGR valve 1 configured as described above, when a part of the exhaust gas of the engine is recirculated to the intake pipe, the switching valve is switched so that the air tank communicates with the first chamber 3d, and the compression in the air tank is performed. Air flows into the first chamber 3d. As a result, the piston 6 moves in the direction indicated by the solid arrow in FIG. 6 against the elastic force of the compression coil spring 9, so that the valve body 4 separates from the valve seat 3c and the through hole 3b is opened,
A part of the exhaust gas flows into the intake pipe through the EGR pipe 2 and the through hole 3b due to the negative pressure in the intake pipe. At this time, although the air in the second chamber 3e is compressed by the piston 6,
The excess air in the second chamber 3e is discharged into the atmosphere through the breathing passage 7, so that the piston 6 moves smoothly in the direction indicated by the solid arrow.

On the other hand, when the switching valve is switched so that the first chamber 3d communicates with the atmosphere, the compressed air in the first chamber 3d is discharged into the atmosphere, and at the same time, the piston 6 is compressed by the compression coil spring 9
Move in the direction of the dashed arrow in FIG. 6 due to the elastic force of
The valve body 4 is seated on the valve seat 3c and the through hole 3b is closed. At this time, the inside of the second chamber 3e has a negative pressure, but the air in the atmosphere flows into the second chamber 3e through the breathing passage 7, so that the piston 6 moves smoothly in the direction shown by the dashed arrow. ing.

[0006]

However, the above conventional E
In the GR valve, as shown in FIGS. 6 and 7, the hole diameter of one end of the breathing passage 7 communicating with the atmosphere, that is, the first concave portion 7a
In addition, since the entrance and exit of the air formed by the second concave portion 7b are large, water and foreign substances may enter the breathing passage 7 in some cases. 6 and 7 in the conventional EGR valve.
Since the breathing passage 7 has a relatively simple shape instead of a maze, there is a risk that water, foreign matter, etc. may enter the piston housing 3a through the breathing passage 7 as shown in FIG. An object of the present invention is to prevent water or foreign matter from entering the respiratory passage without increasing the number of parts, and even if water or foreign matter enters the respiratory passage, water or foreign matter can be suppressed. An object of the present invention is to provide an EGR valve that can prevent the pressure receiving member from reaching the pressure receiver housing.

[0007]

The invention according to claim 1 is
As shown in FIGS. 1 and 4, the EG connects the exhaust passage 18 and the intake passage 19 by bypassing the engine 17.
A valve case 13 provided in the R pipe 12, a valve body 14 accommodated reciprocally in the valve case 13 for communicating or shutting off the EGR pipe 12, and a pressure receiving body 16 connected to the valve body 14; A pressure receiving body accommodating portion 13a formed in the case 13, a first chamber 13d partitioned by the pressure receiving body 16 of the pressure receiving body accommodating portion 13a and communicating with the air supply / discharge means 24, and a pressure receiving body of the pressure receiving body accommodating portion 13a. This is an improvement of the EGR valve provided with the second chamber 13e defined by the second chamber 16 and communicated with the atmosphere through the breathing passage 26. The characteristic configuration is that one end of the both ends of the breathing passage 26 communicating with the atmosphere is formed to have a small hole diameter, and the breathing passage 26 is formed in a maze shape. In the EGR valve according to the first aspect, the hole diameter of one end of the breathing passage 26 is formed small, so that water and foreign matters hardly enter the breathing passage 26. Further, since the breathing passage 26 is formed in a maze shape, even if water, foreign matter, or the like enters the breathing passage 26, it is possible to prevent water, foreign matter, or the like from reaching the pressure receiving body housing portion 13a.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to the drawings. As shown in FIGS.
The GR valve 11 includes a valve case 13 provided in an EGR pipe 12, a valve element 14 reciprocally housed in the valve case 13, and a piston 1 connected to the valve element 14.
6 and a piston accommodating portion 13 a formed in the valve case 13 and slidably accommodating the piston 16. EG
R pipe 12 bypasses engine 17 and exhaust pipe 18
And the intake pipe 19 are connected to each other (FIG. 4).
Reference numeral 3 denotes a timing gear case 21 in which a timing gear for driving a camshaft, a fuel injection pump, and the like is housed.
(FIG. 1). The valve case 13 has E
A through hole 13b communicating with the GR pipe 12 is formed, and a valve seat 13c is formed in the middle of the through hole 13b. Further, the valve element 14 is connected to the piston 16 via a shaft 22, and the shaft 22 is slidably held by a slide bearing 23.

On the other hand, the piston accommodating portion 13a
6, the first chamber 13d on the side opposite to the shaft 22 and the shaft 2
The first chamber 13d communicates with the air supply / discharge means 24, and the second chamber 13e communicates with the atmosphere via the breathing passage 26. The air supply / discharge means 24 includes an air tank 24a in which compressed air is stored, and a switching valve 24c provided in an air pipe 24b that connects the air tank 24a and the first chamber 13d (FIG. 4). The switching valve 24c is a three-port, two-position switching solenoid valve. The first port 24d is connected to the air tank 24a, the second port 24e is connected to the first chamber 13d, and the exhaust port 24f is open to the atmosphere. . When the switching valve 24c is turned on, the first port 24d and the second port 24e communicate with each other, and the air tank 2
4a and the first chamber 13d are connected to each other.
The port 24e communicates with the exhaust port 24f so that the first chamber 1
The compressed air in 3d is configured to be discharged into the atmosphere. A compression coil spring 2 for urging the piston 16 in a direction in which the valve element 14 is seated on the valve seat 13c is provided in the second chamber 13e.
7 are accommodated (FIG. 1).

The breathing passage 26 is formed in a meandering manner.
That is, they are formed in a maze (FIGS. 1 to 3). Specifically, the breathing passage 26 is formed on a surface of the valve case 13 facing the timing gear case 21 and is surrounded by a rib 13f, and a second recess adjacent to the first recess 26a via the rib 13f. 26b, a concave groove 26d formed in the lower wall 13g of the rib 13f, a notch 26e formed in an upper portion of the side wall 13h of the rib 13f, and a bottom surface of the second concave portion 26b communicating with the second chamber 13e. And 26 f formed through holes. The concave groove 26d becomes a square hole-shaped entrance / exit 26g when the valve case 13 is attached to the timing gear case 21. The entrance 26g constitutes one end of both ends of the breathing passage 26 which communicates with the atmosphere, and has a small hole diameter. When the valve case 13 is attached to the timing gear case 21, the cutout portion 26e becomes a small-diameter rectangular hole-shaped throttle portion 26h. Further, the rotation speed of the engine 17 is detected by a rotation sensor 28, and the load of the engine 17 is detected by a load sensor 29 (FIG. 4). Each detection output of the rotation sensor 28 and the load sensor 29 is connected to a control input of the controller 31, and a control output of the controller 31 is connected to the switching valve 24c.

The operation of the EGR valve thus configured will be described. The controller 31 switches the switching valve 24c according to the operating condition of the engine 17, that is, based on the detection outputs of the rotation sensor 28 and the load sensor 29. When returning the exhaust gas to the intake pipe 19, the controller 31 turns on the switching valve 24c to connect the first port 24d and the second port 24e, so that the compressed air in the air tank 24a flows into the first chamber 13d. This allows piston 1
1 moves in the direction shown by the solid arrow in FIG. 1 against the elastic force of the compression coil spring 27, so that the valve body 14 separates from the valve seat 13c, the through hole 13b is opened, and the negative pressure in the intake pipe 19 As a result, a part of the exhaust gas flows into the intake pipe 19 through the EGR pipe 12 and the through hole 13b. At this time, although the air in the second chamber 13 e is compressed by the piston 16,
Since the excess air in the chamber 13e is discharged into the atmosphere through the breathing passage 26, the piston 16 moves smoothly in the direction indicated by the solid arrow.

On the other hand, when the controller 31 turns off the switching valve 24c, the second port 24e communicates with the exhaust port 24f, so that the compressed air in the first chamber 13d is discharged into the atmosphere, and at the same time, the piston 16 is compressed by the compression coil spring. The elastic body 27 moves in the direction of the dashed arrow in FIG. 1, the valve element 14 sits on the valve seat 13c, and the through hole 13b is closed. At this time, although the inside of the second chamber 13e becomes a negative pressure, the air in the atmosphere flows into the second chamber 13e through the breathing passage 26, so that the piston 16 moves smoothly in the direction indicated by the dashed arrow.

Also, while the vehicle is running, rainwater and foreign substances (sand, soil, pebbles, etc.) on the road surface may be splashed up, and these rainwater and foreign substances may hit the valve case 13. However, since the hole diameter at one end of the respiratory passage 26, that is, the entrance / exit 26g, is formed small, the water, foreign matter, and the like cannot pass through the respiratory passage 2
6 difficult to invade. Even if the above-mentioned rainwater or foreign matter
Even if it enters, the respiratory passage 26 is formed in a relatively complicated maze, so that water, foreign matter, etc. can be prevented from reaching the piston accommodating portion 13a. As a result, it is possible to prevent rust from being generated in the piston 16 and the piston accommodating portion 13a, and to prevent foreign matter from being caught between the piston 16 and the piston accommodating portion 13a.

FIG. 5 shows a second embodiment of the present invention.
5, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, the pressure receiving body 56 is a diaphragm, and the air supply / discharge means 64 is the first chamber 53 of the diaphragm accommodating portion 53a.
d. a vacuum pump connected via air line 64a;
And a switching valve provided in the air line 64a. The valve body 54 housed in the valve case 53 is connected to a rubber or soft plastic diaphragm 56 via the shaft 22, and the diaphragm 56 is housed in the diaphragm housing 53a. The diaphragm accommodating portion 53a is partitioned by the diaphragm 56 into a first chamber 53d on the side opposite to the shaft 22 and a second chamber 53e on the side of the shaft 22. A compression coil spring 27 is housed in the first chamber 53d, and the spring 27 biases the diaphragm 56 in a direction in which the valve body 54 is seated on the valve seat 53c. Except for the above, the configuration is the same as that of the first embodiment.

In the EGR valve configured as described above,
When returning the exhaust gas to the intake pipe, the switching valve is turned on and the air in the first chamber 53d is discharged by the vacuum pump. As a result, the diaphragm 56 is deformed against the elastic force of the compression coil spring 27, and moves the shaft 22 together with the valve element 54 in the direction indicated by the solid line arrow.
3c, the through hole 53b is opened, and a part of the exhaust gas is reduced by the negative pressure in the intake pipe to the EGR pipe 12 and the through hole 53b.
Through the intake pipe. At this time, although the inside of the second chamber 53e becomes a negative pressure due to the deformation of the diaphragm 56, the air in the atmosphere flows into the second chamber 53e through the breathing passage 26, so that the shaft 22 smoothly moves in the direction indicated by the solid arrow. Moving.

On the other hand, when the recirculation of the exhaust gas to the intake pipe is stopped, the switching valve is turned off to communicate the inside of the first chamber 53d with the atmosphere. As a result, the atmosphere flows into the first chamber 53d, so that the diaphragm 56 is deformed by the elastic force of the compression coil spring 27, and the shaft 22 moves together with the valve element 54 in the direction indicated by the dashed arrow. Therefore, the valve element 54 is seated on the valve seat 53c, and the through hole 53b is closed. At this time, although the air in the second chamber 53e is compressed, the excess air in the second chamber 53e is discharged into the atmosphere through the breathing passage 26, so that the shaft 22 moves smoothly in the direction indicated by the dashed arrow. I do.
The operation of the EGR valve other than the above is the same as that of the first embodiment.
Since the operation is substantially the same as the operation of the GR valve, the description thereof will not be repeated. In the first embodiment, the piston is described as the pressure receiving body, but a diaphragm may be used. In the second embodiment, the diaphragm is used as the pressure receiving body, but a piston may be used.

[0017]

As described above, according to the present invention, the pressure receiving body housing section is divided into the first chamber and the second chamber by the pressure receiving body.
The first chamber communicates with the air supply / discharge means, the second chamber communicates with the atmosphere through the breathing passage, and the diameter of one end of the both ends of the breathing passage which communicates with the atmosphere is formed small, and the breathing passage is formed. Since it is formed in a maze, it is difficult for water or foreign matter to enter the breathing passage, and even if water or foreign matter enters the breathing passage, it is possible to prevent water or foreign matter from reaching the pressure receiving body housing section. As a result, without increasing the number of parts, it is possible to prevent rust from being generated in the pressure receiving body or the pressure receiving body housing portion, and to prevent foreign matter from being caught between the pressure receiving body and the pressure receiving body housing portion. Can be.

[Brief description of the drawings]

FIG. 1 is a view showing an EGR valve according to a first embodiment of the present invention;
Sectional view on the AA line of FIG.

FIG. 2 is a sectional view taken along line BB of FIG. 1;

FIG. 3 is a sectional view taken along line CC of FIG. 2;

FIG. 4 is a configuration diagram of an engine intake system and an exhaust system including the EGR valve.

FIG. 5 is a sectional view illustrating a second embodiment of the present invention and corresponding to FIG. 1;

FIG. 6 is a sectional view taken along line DD of FIG. 7 showing a conventional example.

FIG. 7 is a sectional view taken along line EE of FIG. 6;

[Explanation of symbols]

 11, 51 EGR valve 12 EGR pipe 13, 53 Valve case 13a Piston accommodating part (pressure receiving element accommodating part) 13d, 53d First chamber 13e, 53e Second chamber 14, 54 Valve element 16 Piston (pressure receiving element) 17 Engine 18 Exhaust Pipe (exhaust passage) 19 Intake pipe (intake passage) 24, 64 Air supply / discharge means 26 Respiratory passage 53a Diaphragm accommodating section (pressure receiving element accommodating section) 56 Diaphragm (pressure receiving element)

Claims (1)

[Claims] An exhaust passage (1) bypasses an engine (17).
8) and a valve case (13) provided in an EGR pipe (12) communicating and connecting the intake passage (19); and the valve case (13).
A valve body (14) that is reciprocally housed in the EGR pipe (12) and communicates or shuts off the EGR pipe (12); And a first chamber (13d) partitioned by the pressure receiving body (16) and communicating with the air supply / discharge means (24) in the pressure receiving body storage section (13a). An EGR valve having a second chamber (13e) defined by the pressure receiving body (16) in the pressure receiving body housing section (13a) and communicating with the atmosphere via a breathing path (26); An EGR valve, wherein a hole diameter of one end of both ends of (26) communicating with the atmosphere is formed small, and the breathing passage (26) is formed in a maze shape.