JPH1122562A - Exhaust gas recirculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly guide the EGR gas as the intake air of an intake system, prevent the temperature rise of a diaphragm, and extend the life of the diaphragm with no increase or a small increase of the number of part items. SOLUTION: An EGR passage 14 connected to the exhaust system of an engine at an inlet 14a and connected to the intake system of the engine at an outlet 14b is formed on a case 13, and a through hole 14d adjusted with the opening by a valve element 16 is formed on the EGR passage 14. A diaphragm storage chamber 18 stretched with a diaphragm 17 deformed in response to the operation state of the engine is formed on the case 13, and the valve element 16 and the diaphragm 17 are connected by a stem 19. A guide wall 13b guiding the EGR gas flowing into the EGR passage 14 to the intake system is provided between a partition wall 13 a partitioning the EGR passage 14 and the diaphragm storage chamber 18 and the through hole 14d in the EGR passage 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas recirculation system for recirculating exhaust gas from an exhaust system of an engine to an intake system.

[0002]

2. Description of the Related Art Conventionally, as a device of this type, an EGR passage for communicating an intake system and an exhaust system of an engine is provided in a housing, and a diaphragm case is integrally provided in the housing. An exhaust gas recirculation device provided with a diaphragm for defining a chamber has been disclosed (JP-A-3-267563). In this device, a valve connected to a diaphragm via a rod is moved toward and away from a valve seat of the housing and the
An annular groove is formed along the circumferential direction on the upstream side of the valve seat portion of the valve seat to open and close the R passage. In the exhaust gas recirculation device configured as described above, the recirculation amount of the EGR gas can be accurately controlled for a long period of time, and when a large amount of deposit is deposited, most of the deposit is deposited in the annular groove. Therefore, the deposit can be easily removed simply by replacing the valve seat.

[0003]

However, in the above-mentioned conventional exhaust gas recirculation device, the high temperature EGR gas directly contacts the upper wall of the housing in which the diaphragm case is mounted and the rod is inserted. As a result, the temperature of the diaphragm becomes high via the diaphragm case. Since this diaphragm is made of an elastic material having relatively low heat resistance such as rubber, there is a possibility that the diaphragm may be deteriorated by this heat. In order to solve this problem, a water-cooling structure has been adopted in which a water-cooled pipe through which cooling water passes is provided on the outer peripheral surface of the diaphragm case or the housing upper part to cool the diaphragm case or the like with water. However, in this water-cooled structure, the shape of the water-cooled pipe is complicated, and there is a problem that the man-hours for manufacturing and assembling the pipe are greatly increased.

SUMMARY OF THE INVENTION An object of the present invention is to enable the EGR gas to be smoothly introduced into the intake air of the intake system without increasing the number of parts or by slightly increasing the number of parts, and to prevent the temperature of the diaphragm from rising so that the life of the diaphragm can be reduced. It is an object of the present invention to provide an exhaust gas recirculation device which can extend the exhaust gas.

[0005]

The invention according to claim 1 is
As shown in FIG. 1 and FIG.
13 having an EGR passage 14 connected to an exhaust system of the engine and having an outlet 14b connected to an intake system of the engine 12.
A through hole 14 d formed in the EGR passage 14, the opening of which is adjusted by the valve body 16, and a diaphragm housing chamber 18 formed in the case 13 and having a diaphragm 17 stretched and deformed in accordance with the operation state of the engine 12. A stem 1 having one end connected to the valve body 16 and the other end connected to the diaphragm 17.
9 is an improvement of the exhaust gas recirculation system provided with the above. The characteristic configuration is such that a guide wall which guides the EGR gas flowing into the EGR passage 14 to the intake system is provided between the partition wall 13a which defines the EGR passage 14 and the diaphragm accommodating chamber 18 of the EGR passage 14 and the through hole 14d. 13b is provided.

In the exhaust gas recirculation system according to the first aspect, the diaphragm 17 is deformed in accordance with the operating condition of the engine 12, so that the valve 1
6 lifts and the through hole 14d opens, so that EGR
High-temperature EGR gas flows into the passage 14. This EGR
After the gas passes through the through hole 14d, the gas comes into contact with the guide wall 13b and its flow direction is changed to a direction toward the intake system.
Smoothly flows into the intake system. In addition, the high temperature E
Since the GR gas is blocked by the guide wall 13b and does not directly contact the partition wall 13a, the temperature rise of the partition wall 13a is suppressed, and therefore the temperature of the diaphragm 17 hardly rises.

As shown in FIG. 5, the EGR passage 14 has an inlet 14a connected to the exhaust system of the engine and an outlet 14b connected to the intake system of the engine.
A case 73 having a through hole formed in the EGR passage 14, the opening of which is adjusted by the valve body 16;
The exhaust gas recirculation system includes a diaphragm housing chamber 18 in which a diaphragm 17 is formed and which is deformed in accordance with the operating condition of the engine, and a stem 19 having one end connected to the valve body 16 and the other end connected to the diaphragm 17. It is an improvement of the circulation device. Its characteristic configuration is that a partition wall 73a that partitions the EGR passage 14 and the diaphragm accommodating chamber 18 and a through hole 14d are provided.
EG that has flowed into the EGR passage 14
The guide plate 74 for guiding the R gas to the intake system is located at the position where the guide plate 74 is fitted. In the exhaust gas recirculation device according to the second aspect, the high-temperature E that flows into the EGR passage 14 from the exhaust system is used.
After passing through the through hole 14d, the GR gas comes into contact with the guide plate 74 and its flow direction is changed to the direction toward the intake system, so that the GR gas flows into the intake system smoothly. Further, since the high-temperature EGR gas is blocked by the guide plate 74 and does not directly contact the partition wall 73a, a rise in the temperature of the partition wall 73a is suppressed, and the temperature of the diaphragm 17 hardly rises.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIGS. 1 to 3, the exhaust gas recirculation device 11 includes a case 13 having an EGR passage 14 having an inlet 14 a connected to an exhaust system of the engine 12 and an outlet 14 b connected to an intake system of the engine 12, Through-hole 1 formed in passage 14 and whose opening is adjusted by valve body 16
4d, a diaphragm accommodating chamber 18 in which a diaphragm 17 formed of an elastic body such as rubber and formed in the case 13 and deformed according to the operating condition of the engine 12 is stretched, and one end is connected to the valve body 16 and the other end is a diaphragm. 17 is connected to the stem 19. The case 13 is formed of an aluminum alloy, and the EGR passage 14 is formed in the case 13 in a substantially inverted L-shape (FIG. 1). Inlet 14a of EGR passage 14
Is connected to an EGR line 22 branched from the exhaust pipe 21,
The outlet 14b of the EGR passage 14 merges with the intake passage 23 formed in the case 13 (FIGS. 1 to 3).

As shown in detail in FIG. 2, a plate 24 is mounted on one end surface of the case 13 so as to close the side surface of the EGR passage 14 and to form an opening 24a facing the inlet 23a of the intake passage 23. An intake pipe 26 is attached to the plate 24 so as to communicate with the intake passage 23 through the opening 24a. An intake manifold 27 is attached to the other end surface of the case 13 so as to communicate with the outlet 23b of the intake passage 23. That is, case 13
Is interposed between the intake pipe 26 and the intake manifold 27,
The intake pipe 26 and the intake manifold 27 communicate with each other through the opening 24a and the intake passage 23 (FIGS. 2 and 3). The EGR passage 14 is connected to the EGR passage 14 from an inlet 14a of the passage 14 through E.
The cylindrical member 14c is inserted into the GR passage 14, and the through hole 14d is formed at the tip of the cylindrical member 14c (FIGS. 1 and 2). A valve seat (not shown) on which the valve body 16 is seated is inserted into the periphery of the through hole 14d.

The diaphragm accommodating chamber 18 is formed by mounting a cap 18a via a diaphragm 17 on the side of the case 13 opposite to the entrance 14a of the EGR passage 14 (FIG. 1). This diaphragm accommodation room 18 and E
The GR passage 14 is separated from the GR passage 14 by a partition wall 13a.
b and an atmospheric pressure chamber 18c. This negative pressure chamber 18b
Accommodates a compression coil spring 18d for urging the diaphragm 17 toward the atmospheric pressure chamber 18c (FIG. 1), and a negative pressure chamber 18b.
Is connected to a vacuum pump 29 via a suction pipe 28 (FIG. 3). The suction pipe 28 is provided with a flow control valve 31. The center of the stem 19 is held slidably in the axial direction and non-rotatably by a slide bearing 32 at its center (FIG. 1). Reference numerals 33 and 34 in FIG. 1 denote a seal member and a seal rubber for keeping the negative pressure chamber 18b airtight. The operating condition of the engine 12 is detected by a load sensor or a rotation sensor (not shown), and the amount of deformation of the diaphragm 17, that is, the amount of lift of the valve body 16 is detected by a position sensor (not shown). The detection outputs of these sensors are connected to a control input of a controller (not shown), and the control output of the controller is connected to a flow control valve 31.

The feature of this embodiment is that the partition wall 1
A guide wall 13b for guiding the EGR gas flowing into the EGR passage 14 to the intake system is provided between the opening 3d and the through hole 14d (FIGS. 1 and 2). The portion of the guide wall 13b farthest from the intake passage 23 is farthest from the partition wall 13a, and the partition wall 13b approaches the intake passage 23 as it approaches.
The part that is inclined so as to approach “a” and is closest to the intake passage 23 is connected to the partition wall 13a (FIG. 1). Partition wall 13
a and a guide wall 13b, a gas reservoir cavity 13c is formed so as to surround a substantially central outer peripheral surface of the stem 19, and the cavity 13c is formed with cooling notches 13d (on both sides of the guide wall 13b). 2) and the EGR passage 14 through the cooling hole 13e (FIGS. 1 and 2). In addition, a through hole 13f into which the stem 19 can be loosely inserted is formed substantially at the center of the guide wall 13b (FIG. 1).

The operation of the exhaust gas recirculation device configured as described above will be described. A controller (not shown) controls the flow control valve 31 based on detection outputs from a load sensor (not shown), a rotation sensor (not shown), and the like of the engine 12 to bring the control valve 31 to a predetermined opening. I do. Since the air in the negative pressure chamber 18b is sucked by the vacuum pump 29 to have a predetermined negative pressure, the diaphragm 17 is deformed toward the negative pressure chamber 18b against the elastic force of the compression coil spring 18d. As a result, the valve body 16 is lifted by a predetermined amount via the stem 19, and the through hole 14d is opened at a predetermined opening degree.
Hot EGR gas flows into the EGR passage 14 via the pipe line 22 as shown by the dashed arrow in FIG. After the EGR gas passes through the through hole 14d, the EGR gas comes into contact with the guide wall 13b and its flow direction is changed to the direction toward the intake passage 23, so that the intake passage 2 smoothly flows as shown by the dashed arrow in FIG.
3 flows into the intake air. Further, the high-temperature EGR gas is blocked by the guide wall 13b and does not directly contact the partition wall 13a, and since the gas reservoir cavity 13c functions as a heat insulating layer, the temperature of the partition wall 13a hardly rises. As a result, the temperature rise of the diaphragm 17 can be prevented, so that the life of the diaphragm 17 can be extended. A cooling notch 13d (FIG. 2) and a cooling hole 13e (FIGS. 1 and 2) communicating the gas reservoir cavity 13c and the EGR passage 14 are formed in the guide wall 13b. And the holes 13e are formed on both sides of the guide wall 13b into which the EGR gas does not easily flow.
R gas hardly flows into the gas reservoir cavity 13c.

On the other hand, when the controller closes the flow control valve 31 based on the output of a load sensor or a rotation sensor, the through hole 14d is closed by the valve body 16 and the EGR is closed.
The flow of the EGR gas into the passage 14 stops. At this time, due to the negative pressure of the intake air passing through the intake passage 23, the EGR gas whose temperature has increased somewhat in the gas reservoir cavity 13c is sucked through the cooling notch 13d and the cooling hole 13e. Can be cooled.

In this embodiment, the intake passage is formed in the case, and the case is interposed between the intake pipe and the intake manifold. However, the intake passage is not formed in the case, and the outlet of the EGR passage is connected through a pipe. May be connected to the intake pipe. In this embodiment, cooling notches and cooling holes are formed on both sides of the guide wall. However, if the temperature of the gas in the gas reservoir cavity hardly rises, these notches and holes are guided. It does not have to be formed on the wall.

FIG. 4 shows a second embodiment of the present invention.
4, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, a throttle portion 53h is formed on an upper wall 53g of the case 53 opposite to the intake passage 23, and the upper wall 5g is formed.
Part of 3g also serves as the guide wall 53b. This aperture 53
h is formed between the partition wall 13a and the through hole 14d, and is the same as that of the first embodiment except for the above, except that the gas reservoir cavity 53c becomes smaller. In the exhaust gas recirculation device configured as described above, since a part of the outer surface of the guide wall 53b is exposed outside the case 53, the high-temperature guide wall 53b contacted with the high-temperature EGR gas is cooled by the cold outside air, The heat conduction to the diaphragm 17 is reduced. The other operations are substantially the same as those of the first embodiment, and the description thereof will not be repeated. Note that a plurality of fins may be formed integrally with the case at the narrowed portion.
As a result, the heat radiation area of the guide wall increases, the guide wall can be cooled more efficiently, and the heat conduction to the diaphragm can be further reduced.

FIG. 5 shows a third embodiment of the present invention.
5, the same reference numerals as those in FIG. 1 indicate the same parts. In this embodiment, a guide plate 74 that guides the EGR gas flowing into the EGR passage 14 to the intake system is provided on the stem 19 between the partition wall 73a defining the EGR passage 14 and the diaphragm accommodating chamber 18 and the through hole 14d. It is fitted. Guide plate 74
Is preferably formed of a steel plate, particularly a stainless steel plate, and is welded to the outer peripheral surface of the boss 75 while being inclined in a predetermined direction. The inclination direction of the guide plate 74 is the same as the inclination direction of the guide wall of the first embodiment. Further, an insertion hole (not shown) is formed in the boss 75, and a female screw (not shown) is formed at a predetermined position of the stem 19. This boss 7
5 is inserted into the stem 19, and a screw (not shown) is screwed into a female screw through an insertion hole to thereby guide the guide plate 74.
Is configured to be fixed at a predetermined position of the stem 19. In the exhaust gas recirculation device configured as described above, since the guide plate 74 operates in substantially the same manner as the guide wall of the first embodiment, repeated description is omitted. In this embodiment, the guide plate is welded to the outer peripheral surface of the boss. However, the guide plate and the boss may be integrally formed by casting an aluminum alloy or the like.

[0017]

As described above, according to the present invention, the EGR passage formed in the case is provided between the partition wall which partitions the EGR passage and the diaphragm accommodating chamber and the through hole.
Since the guide wall for guiding the EGR gas flowing into the R passage to the intake system is provided, the high-temperature EGR gas flowing from the exhaust system into the EGR passage passes through the through hole, and then contacts the guide wall to change its flow direction. It is changed to the direction toward the intake system, and flows smoothly into the intake system. In addition, since the high-temperature EGR gas is blocked by the guide wall and does not directly contact the partition wall, a rise in the temperature of the partition wall is suppressed. As a result, the temperature rise of the diaphragm can be prevented, so that the life of the diaphragm can be extended.

A guide plate for guiding the EGR gas flowing into the EGR passage to the intake system may be fitted to a stem formed between the EGR passage formed in the case and the partition wall defining the diaphragm accommodating chamber and the through hole. After the hot EGR gas flowing from the exhaust system into the EGR passage passes through the through hole, the hot EGR gas comes into contact with the guide plate and its flow direction is changed to the direction toward the intake system, so that it flows into the intake system smoothly. I do. Further, since the high-temperature EGR gas is blocked by the guide plate and does not directly contact the partition wall, a rise in the temperature of the partition wall is suppressed, and the same effect as above can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing an exhaust gas recirculation device according to a first embodiment of the present invention.

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

FIG. 3 is a front view of an engine including the exhaust gas recirculation device.

FIG. 4 is a sectional view showing a second embodiment of the present invention and corresponding to FIG. 1;

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

[Explanation of symbols]

 11, 51, 71 Exhaust gas recirculation device 12 Engine 13, 53, 73 Case 13a, 73a Partition wall 13b, 53b Guide wall 14 EGR passage 14a EGR passage entrance 14b EGR passage exit 14d Through hole 16 Valve body 17 Diaphragm 18 Diaphragm Storage room 19 Stem 74 Guide plate

Claims (2)

[Claims] A case (13, 53) having an EGR passage (14) having an inlet (14a) connected to an exhaust system of the engine (12) and an outlet (14b) connected to an intake system of the engine (12). ), A through hole (14d) formed in the EGR passage (14), the opening of which is adjusted by the valve element (16), and an operation state of the engine (12) formed in the case (13, 53). Diaphragm deformed according to
Exhaust gas recirculation including a diaphragm accommodating chamber (18) in which (17) is stretched, and a stem (19) having one end connected to the valve body (16) and the other end connected to the diaphragm (17). In the device, the EGR passage (14) is provided between a partition wall (13a) that partitions the EGR passage (14) and the diaphragm accommodating chamber (18) of the EGR passage (14) and the through hole (14d). E that flows into
An exhaust gas recirculation device comprising a guide wall (13b, 53b) for guiding GR gas to the intake system. 2. A case (73) having an EGR passage (14) having an inlet (14a) connected to an exhaust system of an engine and an outlet (14b) connected to an intake system of the engine;
The through hole (1) formed in (14) and the opening is adjusted by the valve body (16)
4d), a diaphragm accommodating chamber (18) in which a diaphragm (17) formed in the case (73) and deformed according to the operating condition of the engine is stretched, and one end is connected to the valve body (16). Stem (19) whose other end is connected to the diaphragm (17)
In the exhaust gas recirculation device provided with, in the stem (19) between the partition wall (73a) that partitions the EGR passage (14) and the diaphragm accommodating chamber (18) and the through hole (14d), An exhaust gas recirculation device, wherein a guide plate (74) for guiding EGR gas flowing into the EGR passage (14) to the intake system is fitted.