JPH09196201A - Exhaust gas circulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the floating of a valve body during the application of a high exhaust pressure while preventing a reduction in the durability of a diaphragm and a reduction in the circulation amount of exhaust gas. SOLUTION: The floating of a valve body 5 is prevented by applying a high pressure such as an exhaust pressure to one surface of a valve closing diaphragm 15 for pressing the valve body 5 of an exhaust gas circulation valve 200 during the application of a high exhaust pressure. Thus, the floating of the valve body is prevented without a reduction in the durability of a diaphragm 7 or a reduction in the circulation amount of exhaust gas during the application of a high exhaust pressure. According to another embodiment, the same effect is obtained by electromagnetically pressing the first diaphragm using an electromagnet.

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 device that controls the amount of exhaust gas recirculation from the exhaust side to the intake side of an engine by using an exhaust gas recirculation valve that operates under control pressure.

[0002]

2. Description of the Related Art In an exhaust gas recirculation system, in which a part of exhaust gas is recirculated to the intake path side to suppress the combustion temperature, in order to suppress the amount of NOx produced, the exhaust gas recirculation device is usually used for controlling the exhaust gas recirculation amount. A control valve is provided in the return path. This exhaust gas recirculation valve is closed due to reasons such as output improvement and prevention of excessive recirculation at high exhaust pressure such as during supercharging or exhaust brake operation, but due to high exhaust pressure the valve body opens in the valve opening direction. There is a problem that it is biased and lifts up from the valve seat, causing exhaust gas to recirculate. To solve this problem, the following two techniques have been proposed.

In Japanese Utility Model Laid-Open No. 5-1845, the exhaust gas recirculation amount is controlled by the valve lift amount of an electromagnetic control valve provided in an exhaust recirculation route that recirculates the exhaust gas from the exhaust route of the internal combustion engine to the intake route. In the exhaust gas recirculation valve, a diaphragm is connected to the valve shaft, a negative pressure for control (control negative pressure) is applied to the negative pressure chamber on one side of this diaphragm, and atmospheric pressure is applied to the atmospheric pressure chamber on the other side. In order to compensate for these pressure differences, the diaphragm is biased in the valve closing direction by a spring, and the exhaust pressure is applied to the other side of this diaphragm through a check valve or solenoid valve, so that the exhaust pressure during supercharging is increased. It has been proposed to prevent the valve body from floating due to this high exhaust pressure by urging the valve body in the valve closing direction through the diaphragm at the time of increase and to prevent undesired recirculation of exhaust gas.

Japanese Unexamined Patent Publication (Kokai) No. 5-321769 discloses a structure in which the exhaust pressure acting on the valve body of the exhaust gas recirculation valve urges the valve body in the valve closing direction, so that the valve body is operated at high exhaust pressure. We have proposed an exhaust gas recirculation valve that prevents lifting.

[0005]

However, in the valve body lifting prevention system according to the former publication, the exhaust pressure is introduced into the negative pressure chamber to prevent the valve body from lifting at a high exhaust pressure, so that the negative pressure chamber is large. Negative pressure is generated when the EGR is turned on (valve open) and positive pressure is generated when the EGR is turned off (high exhaust pressure) with respect to the atmospheric pressure chamber. Therefore, the curved peripheral edge portion of the diaphragm is reversed at every pressure reversal, and its durability is remarkably increased. There was a problem of deterioration.

On the other hand, in the valve lift prevention system according to the latter publication, the effective cross-sectional area of the valve hole is reduced and the fluid resistance is increased by the valve shaft that penetrates the valve hole when the EGR is turned on (the valve is opened). There is a problem that the amount of gas recirculation decreases, and further, exhaust gas is deflected toward the center of the shaft, that is, toward the valve shaft through the gap between the valve body and the valve seat, so that solid matter in the exhaust gas accumulates on the valve shaft. However, there is a problem that the reduction of the exhaust gas recirculation amount due to the increase of the fluid resistance is promoted.

The present invention has been made in view of the above problems, and it is possible to prevent the valve body from rising at a high exhaust pressure while suppressing the durability of the diaphragm and the decrease of the exhaust gas recirculation amount due to the deposits. It is an object of the present invention to provide an exhaust gas recirculation device that can be used.

[0008]

According to the apparatus of claim 1, a valve closing diaphragm for urging the valve body of the exhaust gas recirculation valve is provided, and one surface of the valve closing diaphragm is exhausted at a high exhaust pressure. Apply high pressure such as atmospheric pressure to prevent the valve body from rising. With this configuration, it is possible to prevent the valve body from being lifted up at a high exhaust pressure without inducing the durability of the diaphragm or the exhaust gas recirculation amount. Also, E
The differential pressure applied to the GR amount control diaphragm and the valve closing diaphragm is not reversed, and the curved peripheral edge portions of these diaphragms are not reversed.

According to the second aspect of the present invention, since the valve closing diaphragm is elastically coupled to the diaphragm through the elastic biasing means, the structure is simplified. According to the apparatus of claim 3, the diaphragm for urging the valve body of the exhaust gas recirculation valve is provided with the first magnetic member such as a magnet or a soft magnetic body,
An electromagnet is arranged close to the first magnetic member, and when the exhaust pressure is high, the electromagnet is energized to electromagnetically bias (suck or repel) the first magnetic member in the valve closing direction to lift the valve body. Prevent. With this configuration, it is possible to prevent the valve body from being lifted up at a high exhaust pressure without inducing the durability of the diaphragm or the exhaust gas recirculation amount. Further, the differential pressure applied to the diaphragm for controlling the EGR amount is not reversed, and the curved peripheral edge portions of these diaphragms are not reversed.

Alternatively, a second magnetic member that is magnetically attracted to the first magnetic member is provided in the vicinity of the first magnetic member. With this configuration, in the valve closed state, the magnetic attraction force between the magnetic members becomes large, and it is possible to prevent the valve body from rising when the exhaust pressure is high.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the following examples.

[0012]

【Example】

(Embodiment 1) An exhaust gas recirculation device of Embodiment 1 will be described with reference to FIGS. 1 and 2. This exhaust gas recirculation device has an exhaust gas recirculation valve 200 provided in an exhaust gas recirculation path 103 that recirculates exhaust gas from an exhaust path 101 of an internal combustion engine 100 to an intake path 102.

The exhaust gas recirculation valve 200 has a casing 201 having a diaphragm chamber, and a housing 1 fixed to a lower portion of the casing 201 and having a valve chamber therein. The casing 201 includes a first case 8, a second case 9, and a cover 14 in order from the bottom to the top. The casing 201 and the housing 1 form a valve housing according to the present invention.

The valve seat 5 fitted into the housing 1 facing the valve chamber is in contact with the valve body 5 when the valve is closed as shown in FIG.
The valve body 5 is fixed to the lower end of the shaft (valve shaft) 4. The shaft (valve axis) 4 is extended upward along the axis, and the upper end of the shaft 4 is fixed to the central portion of the first diaphragm (diaphragm) 7 in the diaphragm chamber. 3 is a bearing that holds the shaft 4 slidably, and 18 is a bearing holder for fixing the bearing 3.
The bearing holder 18 is sandwiched between the housing 1 and the first case 8.

The peripheral portion of the first diaphragm 7 has first and second peripheral portions.
It is fixed to the cases 8 and 9 when they are crimped,
An atmospheric pressure chamber 10 is defined below the first diaphragm 7 and a negative pressure chamber 11 is defined above the atmospheric pressure chamber 10. Similarly, when caulking the second case 9 and the cover 14, the peripheral edge of the second diaphragm (valve closing diaphragm) 15 is fixed to them, and the negative pressure chamber 11 is provided below the second diaphragm 15 and the upper side thereof. The pressurizing chamber 13 is partitioned and formed. Plates 71 and 72 are individually fixed to both surfaces of the first diaphragm 7, and a spring holder 73 and a plate 74 are fixed to both surfaces of the second diaphragm 15.

The first diaphragm 7 and the second diaphragm 15 are elastically coupled via a spring (elastic biasing means) 12, and one end of the plate 74 is biased by the spring 12 and abuts against the cover 14 in FIG. ing. That is, the plate 74 has a function as a stopper that restricts the displacement of the second diaphragm 15 in the valve opening direction (upward) beyond the allowable level. Reference numerals 19 and 20 denote cylindrical bodies for protecting the sliding portion from solid matter in exhaust gas.

Atmospheric pressure is introduced into the atmospheric pressure chamber 10 of the exhaust gas recirculation valve 200, and negative pressure is introduced into the negative pressure chamber 11 from the vacuum pump V / P through the pipe 104 and the electromagnetic control two-way valve 301. At the same time, atmospheric pressure is introduced through the orifice 303. The intake pressure (supercharging pressure) is introduced into the pressurizing chamber 13 through the pipe 105 and the electromagnetically controlled two-way valve 302, and the atmospheric pressure is introduced through the orifice 304. The spring 12 has both diaphragms 7,
15 is elastically coupled, and when the negative pressure in the negative pressure chamber 11 is at or near atmospheric pressure, the valve body 5 is pressed against the valve seat 6 to close the valve. The orifices 303 and 304 may be small holes that are opened in the second case 9 or the cover 14, and the negative pressure chamber 11 and the pressure chamber 13 and the electromagnetically controlled two-way valve 301,
It may be formed by opening a pipe connecting to 302. 3
A controller 00 controls the electromagnetically controlled two-way valves 301 and 302.

The operation of this exhaust gas recirculation device will be described below. First, the case where the exhaust pressure is not high and the exhaust gas is recirculated (when EGR is on) will be described. In this case, the opening degree of the electromagnetically controlled two-way valve 301 is controlled in a state where the electromagnetically controlled two-way valve 302 is closed and the pressurizing chamber 13 is set to the atmospheric pressure, and the control negative pressure of the negative pressure chamber 11 is set to a desired value. Set. Thereby, the second
The valve body 5 is lifted up in the valve opening direction by being urged by the differential pressure applied to the first diaphragm 7 having an effective pressure receiving area larger than that of the diaphragm 15, and the exhaust gas of a desired flow rate is exhausted through the exhaust path 10.
It is recirculated from 1 to the intake path 102.

Next, the case where the exhaust pressure increases (for example, when the supercharging pressure is applied to the intake passage 102 by the operation of the turbocharger, when the EGR is off) will be described. When the controller 300 detects that the intake pressure (supercharging pressure) exceeds a predetermined level based on an input signal from an engine control unit (ECU, not shown), the controller 300 closes the electromagnetic control two-way valve 301 to close the negative pressure chamber 11. The differential pressure acting on the first diaphragm 7 as atmospheric pressure is set to 0, and the electromagnetically controlled two-way valve 302 is further opened to apply a supercharging pressure to the pressurizing chamber 13, whereby the second diaphragm 1
The valve 5 is biased downward to surely prevent the valve body 5 from rising.

As a modification of this embodiment, the exhaust pressure is introduced into the pressurizing chamber 13 through the electromagnetically controlled two-way valve 302 and the air filter when the exhaust pressure is high to urge the second diaphragm 15 in the valve closing direction. Similar functions can be realized. The effects of this embodiment will be described below. First, since the pressurizing chamber 13 and the second diaphragm 15 are added adjacent to the negative pressure chamber 11, it is not necessary to introduce a positive pressure into the negative pressure chamber 11 as in the conventional case, and inversion of the first diaphragm 7 is avoided. While
It is possible to prevent the valve body 5 from rising.

The upper plate 7 of the second diaphragm 15
4 is bent upward to act as a stopper for supporting the spring 12 when the second diaphragm 15 is not operated, so that the number of parts can be reduced and the second diaphragm 15 can be prevented from being excessively curved in the valve opening direction. . (Embodiment 2) This embodiment shown in FIG.
(See reference), the pipe 1 exiting from the electromagnetically controlled two-way valve 302.
No. 05 is connected to the exhaust path 101 through the air filter 305, and the second diaphragm 15 is operated by using the exhaust pressure instead of the supercharging pressure. The operation itself is the same as that of the first embodiment. is there. However, when the exhaust pressure is not so high (when EGR is on), the urging force of the first diaphragm 7 is superior to that of the second diaphragm 15, so the second diaphragm 15 is maintained at the uppermost position. When the valve is closed, the electromagnetically controlled two-way valve 301
Is closed, and the first diaphragm 7 has a large effective pressure receiving area.
This is the same as the case of the first embodiment in that the biasing force in the valve opening direction is prevented from acting on the valve body 5 due to the differential pressure applied to the valve body 5.

In this embodiment, unlike the first embodiment, it is not necessary to introduce atmospheric pressure into the pressurizing chamber 13 through the orifice 304, but it is also possible if the increase in pollution of the air filter 305 is allowed. . (Embodiment 3) Another embodiment will be described with reference to FIG. However, components having the same functions as those of the first embodiment (see FIG. 1) are designated by the same reference numerals for easy understanding.

Exhaust gas recirculation valve 400 used in this embodiment
Is that the second diaphragm 15 and the second case 9 are omitted from the exhaust gas recirculation valve 200 (see FIG. 1) of the first embodiment, and the first diaphragm 7 is fixed when the cover 14 and the case 8 are caulked. Are different. The difference is that the plate 71 fixed to the lower surface of the first diaphragm 7 is made of soft iron, and the ring-shaped electromagnet 500 is fixed on the base 81 fixed to the case 8. This electromagnet 500
Is a yoke 501 having a ring-shaped slot on the upper surface.
And a coil 503 housed in this slot, and the upper end surface (magnetic pole surface) of the yoke 501 is close to and faces the plate 71.

The operation of this device will be described below. First,
A case where the exhaust pressure is not high and exhaust gas recirculation is performed (when EGR is on) will be described. In this case, the opening degree of the electromagnetically controlled two-way valve 301 is controlled to set the control negative pressure of the negative pressure chamber 11 to a desired value. As a result, the exhaust gas recirculation amount can be controlled as in the case of the first embodiment.

When the exhaust pressure increases (for example, when the turbocharger is actuated to apply the boost pressure to the intake passage 102), the controller 300 receives an input signal from the engine control unit (ECU, not shown). When it is detected that the intake pressure or the exhaust pressure exceeds a predetermined level, the electromagnetically controlled two-way valve 301 is closed to bring the negative pressure chamber 11 to the atmospheric pressure, and the electromagnet 500 is energized to suck the plate 71 downward. Thus, the diaphragm 7 is strongly urged downward, and the valve body 5 is reliably prevented from rising.

A modification of the electromagnet will be described with reference to FIG. In the electromagnet 500 of this embodiment, the peripheral portion is the case 8 and the cover 1.
4 is composed of a disc 501 made of a soft iron thin plate which is crimped together when crimping the disc 4, and a ring-shaped slot 502 that opens upward is formed in the radial center portion of the disc 501 by press molding. The coil 503 is housed in the slot 502. The disk 501 faces the plate 71 in close proximity to each other, and when the coil 503 is energized, both are attracted to each other and the valve body 5 is prevented from rising.

With such a structure, the electromagnet 500 can be realized with a simple structure. It should be understood that the slots 502 can be configured in multiples instead of single or can be formed in various shapes. Further, the valve opening degree can be controlled by controlling the amount of energizing current. Further, the valve structure of this embodiment can be applied to various applications as a small-sized composite valve capable of adjusting the valve opening degree by the diaphragm and adjusting the valve opening degree by the duty control of the energizing current amount.

In particular, according to the valve structure of the present embodiment, the exhaust gas recirculation valve is reliably closed when the exhaust pressure is high, so that the exhaust gas recirculation is prevented and the effect of the exhaust brake is exerted, for example, during the operation of the exhaust brake. Does not diminish, and undesired exhaust gas recirculation does not occur at the time of high supercharging, resulting in no output reduction, and the valve shaft does not penetrate the valve hole, so solid matter such as carbon around the valve hole An excellent effect such as no accumulation can be achieved.

The EGR off condition in each of the above embodiments is judged by the result of comparison between the preset value set in the controller 300 and the input value to the controller 300. Since there is no,
Not detailed. (Embodiment 4) Another embodiment will be described with reference to FIG. However, components having the same functions as those of the third embodiment (see FIG. 4) are designated by the same reference numerals for easy understanding.

Exhaust gas recirculation valve 600 used in this embodiment
In the exhaust gas recirculation valve 400 (see FIG. 4) of Example 3, the base 81 and the electromagnet 500 are omitted, and a ring-shaped permanent magnet (second magnetic member) 601 is fixed to the bottom surface of the case 8.
A ring-shaped magnetic member (first magnetic member) 602 is fixed to the pressing plate 71 immediately above the permanent magnet 601. The top surface of the permanent magnet 601 is a magnetic pole surface. The permanent magnet 601 and the magnetic member 602 constitute the valve closing means at high exhaust pressure according to the present invention.

The operation of this device will be described below. The gap between the permanent magnet 601 and the magnetic member 602 is large when the valve is open and is minimum when the valve is closed. As is well known, in the gap length in the magnetic circuit and the magnetic attraction force between them, the magnetic attraction force tends to rapidly increase as the gap length is reduced.

Therefore, the exhaust gas recirculation valve 6 of this embodiment
In 00, even if the exhaust pressure acting on the valve body 5 is slightly increased by the action of the magnetic attraction force when the valve is closed, the valve body 5 is prevented from rising and the exhaust gas recirculation can be prevented. In this embodiment, a ring-shaped magnetic member (first magnetic member) 6
If 02 is omitted and the pressing plate 71 made of a soft iron plate is disposed close to the permanent magnet 601, the pressing plate 71 can function as the first magnetic member. In addition, the magnetic member 60
2 or the pressing plate 71 may be a permanent magnet, and the permanent magnet 601 may be made of a soft magnetic material. Further, both the magnetic member 602 and the permanent magnet 601 may be permanent magnets.
However, in this case, it is preferable that both are magnetized so as to attract each other.

[Brief description of drawings]

FIG. 1 is a sectional view of an exhaust gas recirculation valve 200 used in an exhaust gas recirculation device of Examples 1 and 2.

FIG. 2 is a first embodiment using the exhaust gas recirculation valve 200 of FIG.
2 is a block diagram of the exhaust gas recirculation device of FIG.

3 is a second embodiment using the exhaust gas recirculation valve 200 of FIG.
2 is a block diagram of the exhaust gas recirculation device of FIG.

FIG. 4 is a cross-sectional view of an exhaust gas recirculation valve 400 used in an exhaust gas recirculation device according to a third embodiment.

FIG. 5 is a sectional view showing a modification of the electromagnet of the exhaust gas recirculation valve 400 of the third embodiment.

FIG. 6 is a sectional view of an exhaust gas recirculation valve 600 used in an exhaust gas recirculation device according to a third embodiment.

[Explanation of symbols]

Reference numeral 101 is an exhaust path, 102 is an intake path, 103 is an exhaust gas recirculation path, 1 is a valve housing, 11 is a negative pressure chamber (first pressure chamber), 10 is an atmospheric pressure chamber (second pressure chamber), and 7 is a first diaphragm. (Diaphragm), 5 is a valve element, 12 is a spring (elastic urging means), 15 is a second diaphragm (valve closing diaphragm, valve closing means at high exhaust pressure), 13 is a pressurizing chamber (third pressure chamber), 71 is a holder (magnetic member), 500 is an electromagnet, and 300 is a controller (energization control circuit).

Claims (3)

[Claims] 1. A valve housing provided in an exhaust gas recirculation path for recirculating exhaust gas from an exhaust path of an internal combustion engine to an intake path, and a diaphragm chamber in the valve housing are partitioned into a first pressure chamber and a second pressure chamber. A diaphragm, a valve body that is biased by the diaphragm to control the amount of recirculation of the exhaust gas, an elastic biasing means that biases the valve body in a valve closing direction, and acts on the valve body at high exhaust pressure. In an exhaust gas recirculation device comprising: a high exhaust pressure closing means for holding the valve element in a valve closed position, overcoming the valve opening pressure due to exhaust pressure, wherein the high exhaust pressure closing means is provided in the diaphragm chamber. A valve-closing diaphragm that is disposed to partition the third pressure chamber from the first pressure chamber and that is biased by the pressure introduced into the third pressure chamber at the time of high exhaust pressure to hold the valve body in the valve-closed position. Special to prepare Exhaust gas recirculation device to collect. 2. The exhaust gas recirculation system according to claim 1, wherein the valve-closing diaphragm biases the diaphragm through a coil spring which constitutes the elastic biasing means. 3. A valve housing provided in an exhaust gas recirculation path for recirculating exhaust gas from an exhaust path of an internal combustion engine to an intake path, and a diaphragm chamber in the valve housing are partitioned into a first pressure chamber and a second pressure chamber. A diaphragm, a valve body that is biased by the diaphragm to control the amount of recirculation of the exhaust gas, an elastic biasing means that biases the valve body in a valve closing direction, and acts on the valve body at high exhaust pressure. An exhaust gas recirculation device comprising: a high exhaust pressure valve closing means for holding the valve element in a valve closed position overcoming a valve opening pressure due to exhaust pressure; wherein the high exhaust pressure valve closing means is attached to the diaphragm. First magnetic member and an electromagnet fixed to the valve housing at a position close to the magnetic member and energized at high exhaust pressure to hold the valve element in the valve closed position or the first magnetic member. An exhaust gas recirculation device, comprising: a second magnetic member that magnetically attracts the member.