JP2000227050A - Exhaust gas recirculating valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress vibration displacement of a valve member, and ensure a prescribed fine valve opening by engaging a stopper device with a valve shaft, and inhibiting the displacement, when the valve member is displaced from a set opening position by reducing a valve opening and increasing a pressure difference between the upstream and downstream sides of the valve member. SOLUTION: When control negative pressure is supplied to a negative pressure chamber 60 of a valve actuator 38 bypassing a leading-in pipe 64 from a control negative pressure source 66 according to an operating condition of an engine, a valve shaft 26 and a valve member 28 fall down against a spring 62 by a first diaphragm 46 to form a valve passage having a small area. In this time, control negative pressure is supplied from the negative pressure source 66 to a control chamber 114, and a spool valve 94 is displaced on a raising position. Negative pressure induced to a negative pressure chamber 88 of a stopper device 70, and a stopper member 68 falls down and so as to abut on an upper end surface of a valve shaft 26. Even if large pressure difference exceeding a setting value between the upstream and downstream sides of the valve member 28 is generated, raising of the valve member 28 is obstructed by the pressure difference, and its opening can be held constantly.

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 valve device.

[0002]

BACKGROUND ART engine, in particular an engine for a vehicle, in order to reduce the NO _x is detrimental components in the exhaust gas, a valve device in the exhaust gas recirculation passage for recirculating a part of exhaust gas to the intake side is provided A device for controlling the flow rate of the recirculated exhaust gas in accordance with the operating state of the engine is known. Conventionally, an exhaust gas recirculation valve device provided with a valve actuator having a negative pressure responsive diaphragm shown in FIG. 3 is disclosed. Have been.

[0003] In FIG. 3, reference numeral 01 denotes a multi-cylinder diesel engine (a four-cylinder engine is illustrated in the figure) for a vehicle. The engine 01 has an exhaust passage 03 including an exhaust manifold 02 and an intake manifold 03. An intake passage 05 including a manifold 04 is provided. Further, an exhaust gas recirculation passage (hereinafter, sometimes referred to as an EGR passage) 06 is provided in which one upstream end communicates with a proper position of the exhaust passage 03 and the other downstream end communicates with a proper position of the intake passage 05. The EGR passage 06 is generally denoted by reference numeral 0.
Exhaust gas recirculation valve (hereinafter referred to as EGR in some cases)
(Referred to as a valve).

The EGR valve 07 has a valve housing 09 having an exhaust gas passage 08 through which recirculated exhaust gas (hereinafter, sometimes referred to as EGR gas) flows. Gas outlet 011
A valve seat 012 is provided at an intermediate portion between the two. Further, a pair of sliding guide members 013 and 01 are provided on the valve housing 09.
4, the valve shaft 015 is slidably supported, and the valve shaft 0
A valve member 016 for controlling the valve opening area in cooperation with the valve seat 012 is mounted at the lower end of the valve seat 15. Note that FIG.
In the figure, the valve member 016 is shown in a fully closed state in which it is seated on the valve seat 012.

At the upper end of the valve shaft 015 protruding outside the valve housing 09, a negative pressure responsive valve actuator indicated generally by reference numeral 017 is disposed. The valve actuator 017 is mounted on the valve housing 09. It is mounted on a U-shaped support member 018 mounted on a bolt or the like.

The valve actuator 017 has a lower casing 019 and an upper casing 020 which are usually formed by pressing a thin steel plate, and a large-diameter outer peripheral edge of which is sandwiched between outer peripheral flanges of the lower and upper casings. First diaphragm or valve opening / closing control diaphragm 021
And a lower casing 019 through which the valve shaft 015 is inserted.
And a small-diameter second diaphragm 022 having an outer peripheral edge fixed to the opening.

The first diaphragm 021 and the second diaphragm 022 are each made of rubber, and the second diaphragm 022 has its inner peripheral edge at holders 023 and 0.
24, and is fixed to the valve shaft 015, and the first diaphragm 021 has an inner peripheral edge portion at the upper and lower pressing plates 02.
5 and 026, it is fixed to the valve shaft 015 by being sandwiched between a nut 027 screwed to the upper end of the valve shaft 015 and a holder 024.

[0008] The pressing plate 026 and the lower casing 019 arranged along the lower surface of the first diaphragm 021.
Return spring 028 is contracted between the bottom wall of the
The first diaphragm 021 is always elastically urged upward by the return spring 028, that is, in the direction in which the valve member 016 closes. Further, the negative pressure chamber 029 is limited by the first and second diaphragms 021 and 022 and the lower casing 019, and a negative pressure is supplied to the negative pressure chamber 029 in accordance with the operation negative pressure of the engine 01. The introduction pipe 030 is connected. On the other hand, the upper casing 020 covering the upper part of the first diaphragm 021 is provided with an atmosphere opening port 031. Therefore, the atmospheric pressure always acts on the upper side surface of the first diaphragm 021.

In the above-described apparatus, when a control negative pressure according to the operating state of the engine is supplied from the load introducing pipe 030 to the negative pressure chamber 029, the negative pressure acts on the upper surface of the first diaphragm 021 and acts on the lower surface. The first diaphragm 021 causes the return spring 02
8 to be deflected downward in the figure, and the return spring 0
The valve shaft 015 moves down to a position where the upward spring force of the valve spring 28 and the downward acting force based on the negative pressure acting on the first diaphragm 021 substantially equilibrate, and the valve member 016 moves to the valve seat 0.
12, the EGR passage 06 is opened.

Therefore, a part of the exhaust gas from the exhaust passage 03 of the engine 01 passes through the exhaust gas passage 08 in the valve housing 09, is returned to the intake passage 05 of the engine 01, is mixed with the intake air, and flows into each cylinder. Supplied to achieve a well-known NO _x reduction effect. The flow rate of the EGR gas is determined by the opening degree of the EGR valve 07, that is, the valve opening area defined by the valve member 016 and the valve seat 012, and the exhaust gas pressure in the exhaust passage 03 and the intake pressure in the intake passage 05. Substantially depends on the pressure difference.

In the conventional EGR valve 07, the negative pressure chamber 02
When the control negative pressure supplied to 9 is a small valve opening degree,
A large pressure difference occurs between the upstream side and the downstream side of the valve member 016. When a large differential pressure acts on the valve member 016, the valve shaft 015 is pushed up first to reduce the valve opening, and then when the valve member 016 rises to some extent, the first diaphragm 021
Since the pushing force based on the negative pressure acting on the valve member exceeds the pushing force based on the differential pressure acting on the valve member 016, the phenomenon that the valve shaft 015 is pushed down again and the valve opening degree increases repeatedly occurs. As a result, the valve opening may change oscillatingly to cause hunting.

As described above, due to the vibrating change of the valve opening, the predetermined valve opening to be set by the control negative pressure introduced into the negative pressure chamber 029 cannot be ensured.
Since the flow rate of the EGR gas flowing through the GR passage 06 changes, there is a concern that the intended NO _x and reduction effects cannot be obtained.
In addition, the first diaphragm 021 and the second diaphragm 0
22 is damaged early due to repeated and frequent operation.
There is a possibility that the durability and reliability of the GR valve 07 may be impaired.

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional EGR valve provided with a valve actuator having a negative pressure responsive diaphragm, and has a small valve opening and an upstream and downstream side of a valve member. Even when a large differential pressure is generated, there is no inconvenience that the valve opening changes oscillatingly, and a constant valve opening corresponding to the control negative pressure can be maintained. Therefore, the desired EGR gas flow rate It is a primary object of the present invention to provide an EGR valve of this type which is capable of stably securing the EGR valve, effectively preventing early breakage of the diaphragm, and having excellent durability and reliability.

[0014]

In order to achieve the above object, the present invention provides a valve housing having an exhaust gas passage therein, and the exhaust gas between an exhaust gas inlet and an exhaust gas outlet in the valve housing. A valve seat provided in the gas passage;
A valve shaft slidably disposed in the valve housing, a valve member mounted on the valve shaft to control a valve opening in cooperation with the valve seat, and controlled in accordance with an operating state of the engine. A valve opening control diaphragm that drives the valve shaft in response to a negative pressure to control the opening of the valve member with respect to the valve seat, and a differential pressure between exhaust gas pressures on the upstream and downstream sides of the valve member. An exhaust gas recirculation valve, comprising: a stopper device that engages with the valve shaft when the valve member is about to be displaced from a set opening position and prohibits displacement of the valve shaft. A device is proposed.

According to the configuration of the present invention, the valve opening is small, the differential pressure of the exhaust gas pressure between the upstream side and the downstream side of the valve member is large, and the valve member is displaced from the set opening position. In this state, the stopper device engages with the valve shaft to prohibit the displacement of the valve shaft based on the differential pressure, so that the vibrational displacement of the valve member is reliably suppressed, and the stopper is adapted to the operating condition of the engine. A predetermined minute valve opening corresponding to the control negative pressure is ensured, and early breakage of the valve opening control diaphragm is prevented.

[0016] In the present invention, the stopper device includes:
A stopper member that abuts on the valve shaft and prohibits displacement in the valve opening direction, and a stopper that is operatively connected to the stopper member and that displaces the stopper member to a position in contact with the valve shaft in response to a negative pressure It is preferable to include a control diaphragm and a control valve that controls supply of a negative pressure to the stopper control diaphragm in response to a control negative pressure supplied to the valve opening control diaphragm. Further, it is desirable that the valve member is disposed in the exhaust gas passage at an upstream side of the valve seat.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS. In the figure, reference numeral 10 generally indicates an EGR valve, and the EGR valve 10 is an EGR passage 12 substantially similar to the EGR passage 06 in FIG.
(Only a part thereof is shown by a dashed line in FIG. 1), and a valve housing 16 having an exhaust gas passage 14 provided therein is provided.

The exhaust gas inlet 18 of the exhaust gas passage 14
A valve seat 22 is provided at an intermediate portion between the valve housing 16 and the exhaust gas outlet 20, and a valve shaft 26 is slidably inserted into a sliding guide member 24 mounted on the valve housing 16. Valve shaft 26
A disk-shaped valve member 28 for controlling the valve opening area in cooperation with the valve seat 22 is mounted at the lower end of the upper and lower members via upper and lower support members 30 and 32.

A U-shaped or cup-shaped support member 34 is fixed on the valve housing 16 by bolts or screws 36. The support member 34 supports a valve actuator indicated generally by reference numeral 38. I have. The valve actuator 38 is operatively connected to an upper end of the valve shaft 26 protruding from the valve housing 16 as will be described later in detail.

The valve actuator 38 is connected to the valve shaft 2.
A lower casing 42 having a cup-like shape having a central opening 40 through which the inner casing 6 is inserted coaxially, and an upper casing 44 in the form of a shallow dish, which is mounted with its outer peripheral flange overlapped with the upper end flange of the lower casing 42. A first rubber diaphragm or valve opening control diaphragm 46 whose outer peripheral edge is sandwiched by outer peripheral flanges of the lower casing 42 and the upper casing 44, and a lower end portion of the central opening 40. A second diaphragm 48 fixed to the periphery.

The second diaphragm 48 has its central portion sandwiched between upper and lower holders 50 and 52.
The first diaphragm 46, which has a remarkably large pressure receiving area as compared with the diaphragm 48, has its central portion fixed to the upper end portion of the valve shaft 26 by the holder 50 and the tightening nut 58 via upper and lower pressing plates 54 and 56. Have been. The negative pressure chamber 60 is limited by the first diaphragm 46, the lower casing 42, and the second diaphragm 48. In addition, on the upper surface of the first diaphragm 46,
Atmospheric pressure is constantly applied through a vent hole 44 'provided in the upper casing 44.

A return spring 62 contracted between the holding plate 56 and the bottom wall of the lower casing 42 is accommodated in the negative pressure chamber 60. One end is connected. The other end of the negative pressure introducing pipe 64 is connected to a control negative pressure source 66 that generates a control negative pressure according to the operation state of the engine.

On the upper casing 44, the valve shaft 2
A stopper device 70 having a plunger-like stopper member 68 arranged coaxially with respect to 6 is provided. The stopper device 70 includes a lower housing 74 abutted on the upper surface of the upper casing 44 by bolts or screws 72.
And an upper housing 76, and a rubber-made third diaphragm or stopper control diaphragm 78 whose outer peripheral edge is sandwiched between flange portions of the lower and upper housings 74 and 76, the third diaphragm 7.
The stopper member 68 is fixed to the central portion of 8 via a holding plate 80 and a holding ring 82. The retaining ring 82 can be fixed to the stopper member 68 by press-fitting.
It is also possible to use a nut which is screwed into a threaded portion engraved on the nut. Atmospheric pressure is constantly applied to the upper surface of the third diaphragm 78 via a vent hole 76 'provided in the lid of the upper housing 76.

A through hole 84 is provided on the bottom wall of the lower casing 74 to allow free displacement of the stopper member 68 in the axial direction of the valve shaft.
The outer peripheral edge of a rubber-made fourth diaphragm 86 having a diameter sufficiently smaller than that of the diaphragm 78 is air-tightly fixed by bonding, fixing with a holding plate, or other appropriate fixing means, and the central portion of the fourth diaphragm 86 is bonded and tightened with a band And airtightly connected to the stopper member 68 by other appropriate fixing means.

The negative pressure chamber 8 is formed by the lower casing 74, the third diaphragm 78 and the fourth diaphragm 86.
A return spring 9 is provided in the negative pressure chamber 88 to constantly urge the third diaphragm 78 upward.
0 is stored. Further, one end of a negative pressure introducing pipe 92 is connected to the negative pressure chamber 88, and the other end of the negative pressure introducing pipe 92 is
Valve casing 9 of control valve 96 with built-in spool valve 94
8 is connected to a first port 100 provided in the first port 8.

The valve casing 98 is always provided with a second port 104 connected to a negative pressure source 102 such as a vacuum pump driven by an engine. Regardless of how it is arranged, it is arranged so as to communicate with the annular groove 110 on the outer periphery of the small diameter portion between the two lands 106 and 108. Also,
A return spring 112 is disposed between the land 106 and the opposite end wall of the valve casing 98 to constantly bias the spool valve 94 elastically toward the rest position shown in FIG.
The control chamber 114 containing the return spring 112 is provided with a third port 116 communicating with the control negative pressure source 66. Further, a fourth port 118 is provided in the valve casing 98 on the land 108 side, and the fourth port 118 communicates with the atmosphere.

FIG. 1 shows the control negative pressure source 66 supplied to the negative pressure chamber 60 of the valve actuator 38 in the EGR valve 10 when the engine is stopped or the engine is not operating in the EGR mode. The control negative pressure is the atmospheric pressure, or the negative pressure introduced into the negative pressure chamber 60 from the control negative pressure source 66 is sufficiently small, and the force based on the negative pressure acting on the first diaphragm or the valve opening control diaphragm 46. Return spring 62 is not overcome, and
The valve member 28 is in contact with the valve seat 22 by the urging force of the return spring 62 via the valve shaft 26, and the valve opening is zero, that is, fully closed.

On the other hand, since the control negative pressure of the control negative pressure source 66 supplied to the third port 116 of the control valve 96 is substantially atmospheric pressure or the supplied negative pressure is sufficiently small, the return spring 112 As a result, the spool valve 94 is held at the rest position shown in the drawing, the communication between the first port 100 and the second port 104 is cut off by the land 106 of the spool valve 94, and the first port 100 and the third port 106
And the negative pressure chamber 88 of the stopper device 70
, An atmospheric pressure or a sufficiently small negative pressure is introduced from a negative pressure source 66 through a negative pressure introducing pipe 92. Therefore, the third diaphragm or the stopper control diaphragm 78 is held at the rest position shown in the drawing by the return spring 90, and the lower end surface of the stopper member 68 does not abut or engage with the upper end surface of the valve shaft 26.

Next, FIG. 2 shows that a relatively small preset control negative pressure is applied to the negative pressure chamber 60 of the valve actuator 38 from the control negative pressure source 66 via the negative pressure introducing pipe 64 in accordance with the operation state of the engine. The return spring 62 is slightly compressed by the downward force generated in the first diaphragm 46 on which the control negative pressure is supplied, and the valve shaft 26 and the valve member 28 are lowered, and the valve member 28 and the valve seat 28 are lowered. 22 shows a state in which a valve passage having a small area is formed between the valve passage 22 and the valve opening 22. At this time, a small amount of exhaust gas corresponding to the minute opening of the valve member 28 flows from the engine exhaust passage through the EGR passage 12 and the EGR valve 10 to the engine intake passage.

Since the opening degree of the valve member 28 is small, a large exhaust gas pressure difference exceeding a set value is generated between the upstream side and the downstream side, and the valve opening degree is applied to the valve member 28 based on the pressure difference. A push-up force in the direction of decreasing acts to raise the valve shaft 26. As described with respect to the conventional EGR valve, when the stopper device 70 is not provided, the valve shaft 26 and the valve member 28 are vertically displaced and vibrated, so that the valve opening degree is very small according to the control negative pressure. There was a problem that the opening could not be maintained at the set opening, and it was difficult to use the opening at a very small opening. However, the EGR shown in FIGS.
In the valve 10, as will be described in detail below, the oscillating change in the valve opening degree at a minute opening degree of the valve member 28 is reliably prevented, and EGR with a small flow rate is easily realized.

That is, the set control negative pressure is also supplied to the control chamber 114 from the third port 116 of the control valve 96 and acts on the land 106 of the spool valve 94.
Due to the pressure difference from the atmospheric pressure acting on the land 108 introduced from the port 118, the return spring 112 having a relatively small spring constant is overcome, and the spool valve 94
Moves to the operating position or the ascending position shown in the figure.

By the displacement of the spool valve 94 to the operating position, the first port 100 and the second port 104 communicate with each other through the annular groove 110 between the lands 106 and 108,
A large negative pressure from the negative pressure source 102 is introduced into the negative pressure chamber 88 of the stopper device 70 via the negative pressure introducing pipe 92. As a result, the third diaphragm or the stopper control diaphragm 7
8 compresses the return spring 90 and descends.
The stopper member 68 fixed to the diaphragm 78 descends to the position shown in the drawing and contacts the upper end surface of the valve shaft 26, and the valve member 28
The upward displacement of the valve shaft 26 is suppressed in opposition to the pushing force based on the differential pressure of the exhaust gas pressure acting on the valve member 38, and the opening of the valve member 28 is controlled by the control valve supplied to the negative pressure chamber 60 of the valve actuator 38. The opening is maintained at a constant value corresponding to the pressure.

Therefore, when the opening degree of the valve member 28 is small, the disadvantage of the conventional EGR valve in which the valve member 28 is displaced vibrating and the EGR gas amount fluctuates is solved, and the required EGR gas flow rate is reduced. In addition to this, it is possible to effectively prevent early breakage based on the vibrational displacement of the first diaphragm or the valve opening control diaphragm 46, and to ensure the durability and reliability of the valve actuator 38 and thus the EGR valve 10. There are benefits to gain.

Note that, according to the operating state of the engine, FIG.
In the case where a larger amount of EGR gas is generated than in the state described above, the control negative pressure supplied from the control negative pressure source 66 to the negative pressure chamber 60 of the valve actuator 38 becomes correspondingly large, and the first diaphragm 46 responds to the control negative pressure. The valve shaft 26 and the valve member 28 are displaced further downward, and the valve opening is increased. When the valve opening increases, the differential pressure of the exhaust gas pressure between the upstream side and the downstream side of the valve member 28 becomes extremely small, and the pushing force based on the differential pressure acting on the valve member 28 can be practically neglected. About to be small. At this time, the negative pressure of the negative pressure source 102 does not change in the negative pressure chamber 88 of the stopper device 70, and the stopper member 68 is lowered to the operating position. This does not adversely affect the increase in the opening degree and the maintenance of the set opening degree.

As the stopper device 70, similarly to the valve actuator 38, a third diaphragm or stopper control diaphragm 78 and a small-diameter fourth diaphragm for maintaining airtightness.
A negative pressure responsive actuator having a negative pressure chamber 88 limited by a diaphragm 86 and a lower housing 74, and a control preferably including a spool valve 94 for controlling the supply and discharge of negative pressure to the negative pressure chamber 88. By employing the valve 96, it is possible to provide an inexpensive device that is simple in structure, small in size and light in weight. In addition, with the configuration in which the valve member 28 is disposed on the upstream side of the valve seat 22, if the first diaphragm 46 is broken, the return spring 62 closes the valve member 28, so that EGR is performed. However, there is no problem that the driving performance such as the output of the engine deteriorates remarkably, and there is a safety advantage.

The present invention is not limited to the above embodiment, and various changes and modifications can be made to the above embodiment within the scope of the claims. For example,
Control valve 96 having spool valve 94 responsive to control vacuum
Instead, a rotary valve or an electromagnetic valve that operates by detecting a minute opening degree of the valve member 28 or the like can be appropriately adopted. Further, the valve member 28 is not limited to the configuration in which the valve member 28 is disposed on the upstream side of the valve seat 22. When the valve member 28 is disposed on the downstream side of the valve seat 22 and the opening degree of the valve member 28 is small, The present invention can also be applied to a case where a large differential pressure is generated between the valve member 28 and the downstream side, and the opening degree of the valve member 28 changes in an oscillatory manner.

[0037]

As described above, the exhaust gas recirculation valve device according to the present invention includes a valve housing having an exhaust gas passage therein, and an exhaust gas inlet and an exhaust gas outlet within the valve housing. A valve seat provided in the exhaust gas passage of
A valve shaft slidably disposed in the valve housing, a valve member mounted on the valve shaft to control a valve opening in cooperation with the valve seat, and controlled in accordance with an operating state of the engine. A valve opening control diaphragm that drives the valve shaft in response to a negative pressure to control the opening of the valve member with respect to the valve seat, and a differential pressure between exhaust gas pressures on the upstream and downstream sides of the valve member. A conventional valve device comprising a stopper device that engages with the valve shaft when the valve member is about to be displaced from the set opening position and prohibits displacement of the valve shaft. Thus, there is an advantage that it is possible to stably perform the minute opening position control of the valve member, which has been difficult to use, and to provide an EGR valve device excellent in durability and reliability.

In the present invention, the stopper device contacts the valve shaft and inhibits its displacement in the valve closing direction, and the stopper device is operatively connected to the stopper member and responds to a negative pressure to respond to the negative pressure. A stopper control diaphragm for displacing a member to a position where it abuts on a valve shaft, a control valve for controlling supply of a negative pressure to the stopper control diaphragm in response to a control negative pressure supplied to the valve opening control diaphragm; Is advantageous in that it is possible to provide an inexpensive configuration with a simple structure, small size and light weight.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a state in which an EGR valve is fully closed in a preferred embodiment of the present invention.

FIG. 2 is a sectional view showing a state of the EGR valve shown in FIG. 1 at a minute opening degree.

FIG. 3 is a schematic configuration diagram showing a conventional negative pressure responsive valve actuator.

[Explanation of symbols]

10: EGR valve, 12: EGR passage, 14: exhaust gas passage, 16: valve housing, 18: exhaust gas inlet, 20 ...
Exhaust gas outlet, 22 ... valve seat, 26 ... valve shaft, 28 ... valve member, 38 ... valve actuator, 46 ... first diaphragm or diaphragm for controlling valve opening, 48 ... second diaphragm, 60 ... negative pressure chamber, 62 … Return spring, 64…
Negative pressure introducing pipe, 66 ... Control negative pressure source, 68 ... Stopper member,
70: stopper device, 78: third diaphragm or stopper control diaphragm, 86: fourth diaphragm, 88
... negative pressure chamber, 90 ... return spring, 92 ... negative pressure introduction pipe, 94 ... spool valve, 96 ... control valve, 102 ... negative pressure source.

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Claims (3)

[Claims] A valve housing having an exhaust gas passage therein; a valve seat provided in the exhaust gas passage between an exhaust gas inlet and an exhaust gas outlet within the valve housing;
A valve shaft slidably disposed in the valve housing, a valve member mounted on the valve shaft to control a valve opening in cooperation with the valve seat, and controlled in accordance with an operating state of the engine. A valve opening control diaphragm that drives the valve shaft in response to a negative pressure to control the opening of the valve member with respect to the valve seat, and a differential pressure between the exhaust gas pressures on the upstream and downstream sides of the valve member. An exhaust gas recirculation valve, comprising: a stopper device that engages with the valve shaft when the valve member is about to be displaced from a set opening position and prohibits displacement of the valve shaft. apparatus. 2. The stopper device according to claim 1, wherein said stopper device is in contact with said valve shaft to inhibit displacement thereof in a valve closing direction, and said stopper device is operatively connected to said stopper member to move said stopper member in response to a negative pressure. A stopper control diaphragm for displacing to a position in contact with the valve shaft; and a control valve for controlling supply of a negative pressure to the stopper control diaphragm in response to a control negative pressure supplied to the valve opening control diaphragm. The exhaust gas recirculation valve device according to claim 1, wherein: 3. The exhaust gas recirculation valve device according to claim 1, wherein the valve member is disposed upstream of the valve seat in the exhaust gas passage.