JPH0979416A - Multiple stage open stroke valve device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain two kinds of small valve lift maintaining sufficient maximum valve lift by supplying operating medium to both of the first and the second charge/discharge ports to displace the first, the second and the third piston to open a valve member to the extent of total open stroke of the first, the second and the third open stroke. SOLUTION: Allowable displacement of the first piston 26 to the direction of a valve member 16 is L2 , allowable displacement of the second piston 30 from the first piston 26 of the direction of the valve member 16 is L3 , and allowable displacement of the third piston 48 from the second piston 30 of the direction of the valve member 16 is L1 . The setting stroke L2 of the first piston 26 can be freely set by changing the thickness of a shim 7 inserted between an upper housing 12a and a lower housing 12b, for instance. The setting stroke L3 and L2 of the second piston 30 and the third piston 48 can be changed with the thickness of the first and the second stopper ring 38 and 54, etc., without changing the fundamental dimension of each piston 26, 30 and 48.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device capable of controlling the valve opening in multiple stages, and more particularly to a multi-stage opening valve device suitable for use in an EGR control valve of a vehicle diesel engine. .

[0002]

As is well known in the art, in order to reduce NO _x in the exhaust gas of a vehicle engine, the flow rate of a part of the exhaust gas of the engine is controlled according to the operating state of the engine. The so-called EG that recirculates to the intake system of the engine
For the R control valve, a diaphragm type fluid pressure response device is widely adopted as an actuator for controlling the valve opening. However, in the EGR control valve equipped with the diaphragm actuator, the valve opening is controlled by controlling the fluid pressure (usually compressed air pressure or negative pressure) acting on the diaphragm, so that the fluid pressure is adjusted. Since a pressure device and feedback control are required, the structure is complicated, and the valve opening easily changes due to slight disturbance, so there is a problem that it is difficult to perform reliable valve opening control for a long period of time.

By solving the above problems of the EGR control valve having the diaphragm type actuator, it is possible to perform easy and accurate valve opening control without requiring precise adjustment of working fluid pressure and complicated feedback control. A possible multistage opening EGR control valve has already been disclosed in Japanese Utility Model Laid-Open No. 5-47401.

FIG. 11 shows a schematic structure of the previously proposed valve device.
Reference numeral 01 in the figure generally indicates an EGR control valve device for an engine for a vehicle, which valve device extracts an exhaust gas of the engine and recirculates it to an intake system. A housing 02 installed inside (not shown)
It is equipped with Inside the housing 02, an exhaust gas passage 03, a valve member 04 formed of a poppet valve interposed in the exhaust gas passage 03 for controlling the exhaust gas flow rate, and a valve stem 04 ′ of the valve member 04 are operatively operated. And an actuator 05 that is connected to the valve and controls the valve opening degree or lift.

The actuator 05 has a housing 0.
2, a cylinder 06 formed substantially coaxially with the valve stem 04 ', a first piston 07 slidably fitted in the cylinder 06, and a slide in the first piston 07. The second piston 08 is freely fitted and fixed to the end of the valve stem 04 '. The first piston 07 is composed of a hollow cylindrical tubular member 07a fitted in the cylinder 06, and a piston member 07b fixed to the opening end of the tubular member 07a remote from the valve member 04 by a snap ring 09. Therefore, the valve member 04 of the tubular member 07a
A projecting edge or a stopper 010 that projects inward in the radial direction is provided at the open end on the side. The second piston 08 is slidably accommodated in the hollow hole of the cylindrical member 07a.

At the end of the housing 02 remote from the valve member 04, a working medium source is provided via an electromagnetic three-way valve (not shown).
For example, a first supply / discharge port 011 connected to a compressed air source is provided, and the port 011 is always in communication with the first working chamber 012 that is limited by the first piston 07 in the cylinder 06. In addition, the side wall of the housing 02 has a second
A supply / discharge port 013 is provided, and the port 013 is provided in the cylinder 06 with the first piston 07 and the second piston 0.
8 is always in communication with the second working chamber 014 defined by 8 and 8. Further, the second piston 08 and the cylinder 0
A valve spring 015 for constantly urging the valve member 04 in the closing direction is provided between the end wall of the valve member 6 and the end wall on the valve member 04 side.

FIG. 11 shows the first and second supply / discharge ports 0.
No compressed air is supplied to both 11 and 013, and both ports are in communication with the atmosphere. At this time, the valve member 04 is fully closed, and there is a gap l ₁ that limits the first valve lift in the valve axis 04 ′ direction between the stopper 010 of the first piston 07 and the shoulder 016 of the cylinder 06. And the second piston 08 has the above-mentioned valve spring 015.
Is pushed by the first piston 07 and abuts on a push rod 017 provided integrally with the first piston 07.
Between the piston 08 and the stopper 010, the valve shaft 04 '
A gap l ₂ is provided which limits the second valve lift in the direction.

Next, when compressed air is supplied from the first supply / discharge port 011 to the first working chamber 012, the first piston 07
However, the valve spring 015 is compressed via the second piston 08 and the end surface of the stopper 10 on the valve member 04 side is displaced until it comes into contact with the shoulder portion 016 of the cylinder, and the valve member 04 is moved to the first lift or opening l. open by _one, in the exhaust gas passage 03, the exhaust gas flow rate commensurate with the first lift l ₁ of the valve member 04 flows, is supplied to the intake system of the engine. When compressed air is supplied from the second supply / discharge port 013 to the second working chamber 014 (note that the first supply / discharge port 011 remains open to the atmosphere), the second piston 08 independently operates the valve spring 01.
5 is compressed and displaced until it comes into contact with the stopper 010, the valve member 04 opens by the second lift or the opening l ₂ , and the exhaust gas passage 03 has a flow rate corresponding to the second lift l ₂ of the valve member 04. Exhaust gas flows and is supplied to the intake system of the engine.

Further, when compressed air is supplied to both the first and second supply / discharge ports 011 and 013, the first piston 07 and the second piston 08 cause the first lift l ₁ and the second lift l _{2 to} move. since respectively displaced by the valve shaft 04 'direction, the lift or opening _{l 3} of the valve member 04 _(l 1 ₊ l 2)
Becomes

Therefore, if the minimum required valve lift or opening of the valve member 04 is 1 mm and the maximum valve lift is 10 mm in accordance with the operating state of the engine (in the illustrated case, l ₂ = 1 mm). , L ₃ = 10 mm) and the intermediate lift l ₁ = 9 mm. That is, in this proposed valve device, the minimum lift l ₂ = 1 mm and the maximum lift l ₃ = 10
Three types of lift with an intermediate lift l ₂ = 9 mm close to mm are obtained, in other words one type of small lift and two types of large lift. Therefore, when a minimum valve lift or opening, for example, 1 mm and a second valve lift or opening 2 mm, which is slightly larger than that, is required from the operating conditions on the engine side, the maximum lift is required in this proposed valve device. l ₃
= L ₁ + l ₂ is only 3 mm, and a sufficient maximum lift or opening cannot be obtained structurally. As a result, in order to achieve effective reduction of engine performance, particularly NO _{x in} exhaust gas, it is not possible to broadly select three types of valve lift or opening of the EGR control valve device. Therefore, there is a problem that the required engine performance cannot be obtained.

[0011]

DISCLOSURE OF THE INVENTION The present invention solves the drawbacks of the previously proposed multi-stage opening valve device and allows a wide selection of three-stage valve lift or opening. The main object of the present invention is to provide a valve device that can easily obtain two kinds of small valve lifts or opening amounts while securing the valve lifts. The present invention is a vehicle engine, particularly when applied to the EGR control valve unit in a diesel engine such as a truck, the output, while ensuring the engine performance such as fuel consumption, reduce NO _x in the exhaust gas effectively It is another object to provide a multi-stage opening valve device that can be used.

[0012]

SUMMARY OF THE INVENTION The present invention was devised to achieve the above object, and is provided in a fluid passage,
A valve member for controlling the fluid flow rate by setting the opening degree in multiple stages, a first piston slidably fitted in a first cylinder provided in the housing, and a first piston A second cylinder formed substantially coaxially with the second cylinder, and a second piston slidably fitted in the second cylinder,
A third cylinder formed substantially coaxially in the second piston, a third piston slidably fitted in the third cylinder and operatively connected to the valve member, and a valve member Only the third piston is provided by supplying the working medium to the elastic device that is connected and normally biases the valve member in the closing direction, and the third working chamber that is provided in the housing and that is formed in the second cylinder. In the valve opening direction to open the valve member by the first opening L ₁ and a first working chamber provided in the housing and formed in the first cylinder. By supplying the medium, the first
A second supply / discharge port for displacing the piston in the valve opening direction to open the valve member by the second opening L ₂ via the second piston and the third piston, the first supply / discharge port and the second supply / discharge port. By supplying the working medium to both the ports, the working medium is supplied to the first to third working chambers, and the first piston, the second piston, and the third piston are displaced in the valve opening direction. A multistage structure in which the valve member is opened by a total opening amount L ₁ + L ₂ + L _{3 obtained} by adding the third opening amount L ₃ of the second piston to the 2 opening amounts L ₁ and L ₂ . An opening valve device is proposed.

In the present invention, a first passage for communicating the first supply / discharge port with the third working chamber in the second piston in the housing, and the first supply / discharge port and the first passage.
A second passage communicating with a second working chamber in the piston is provided, and the second passage is closed by the first piston when the working medium is supplied only to the first supply / discharge port. However, when the working medium is supplied to the second supply / discharge port, it is preferable that the second piston is configured to be opened by the displacement of the first piston. Further, a fourth working chamber facing the pressure receiving surface opposite to the pressure receiving surface facing the third working chamber of the third piston is provided in the housing, and the working medium is supplied to and discharged from the fourth working chamber. It is preferable to provide a third supply / discharge port.

Further, in the present invention, the fluid passage is an EGR passage for supplying a part of exhaust gas of the engine to an intake system of the engine, and the valve member supplies a flow rate of the exhaust gas to the intake system. It is preferable that the working medium supplied to the first and second supply / discharge ports is compressed air, and the first and second supply / discharge ports have the first and second supply / discharge ports. Each is preferably connected to a compressed air source via two electromagnetic three-way valves. Similarly, the working medium supplied to the third supply / discharge port is compressed air, and the third supply / discharge port is preferably connected to the compressed air source via the third electromagnetic three-way valve.

When the present invention is applied to the EGR control valve as described above, the engine operates in the first operating range where the engine speed is equal to or lower than the preset middle speed and the load is equal to or lower than the preset load. During operation, the working medium is supplied to the first and second supply / discharge ports, the first to third pistons are all displaced in the valve opening direction, and the valve member adds the first to third opening degrees. is opened by L _{1 +} L 2 ₊ L ₃ that, also when the engine is operated in the second operating region below the load in the above set medium speed rotational speed, and set in advance, the second
The working medium is supplied only to the supply / discharge port, the first piston is displaced in the valve opening direction, the valve member is opened by the second opening L ₂ via the second and third pistons, and the engine is When operating in a third operating region having a higher load than the first and second operating regions and a preset rotational speed lower than or equal to a high speed rotational speed, the working medium is supplied to the first supply / discharge port, It is preferable that only the third piston is displaced in the valve opening direction so that the valve member is opened by the first opening degree L ₁ , and the engine is configured such that the engine has the first to third openings.
When operating in an operating region other than the operating region, when the engine is rapidly accelerated, and when the cooling water temperature of the engine is equal to or lower than the set temperature, the working medium is not supplied to any of the first and second supply / discharge ports. Not supplied, the valve member is configured to be held in the closed position by the elastic device, and the working medium is supplied to the third supply / discharge port when the valve member is closed from the open state. The third piston is preferably configured to be biased in the valve member closing direction.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments in which the present invention is applied to an EGR control valve of a vehicle diesel engine will be specifically described below with reference to the accompanying drawings. First, in the first embodiment shown in FIGS. 1 to 8, reference numeral 10 generally indicates an EGR control valve, and the EGR control valve 10 extracts a part of the exhaust gas of the engine and intakes it. The housing 12 is provided in an EGR passage (reference numeral 86 in FIG. 5) that returns to the system. Inside the housing 12,
A valve member 16 including an exhaust gas passage 14 and a poppet valve that is interposed in the exhaust gas passage 14 and controls the flow rate of the exhaust gas.
And an actuator 20 operatively connected to the valve stem 18 of the valve member 16 to control the valve opening degree or lift.

The housing 12 is composed of an upper housing 12a and a lower housing 12b which are divided along a plane substantially orthogonal to the valve stem 18 of the valve member 16, and the upper and lower housings 12a and 12b are provided with a plurality of bolts 22 ( (Only one is shown in FIG. 1). In the upper housing 12a, a first cylinder 24 is provided which is opened substantially toward the valve member 16 side, substantially coaxially with the valve stem 18, and a large-diameter first piston 26 is provided in the first cylinder 24. It is fitted so as to be slidable in the valve axis direction. Inside the first piston 26, a second cylinder 28 opened toward the valve member 16 side.
Are formed substantially coaxially. A second piston 30 is slidably fitted in the second cylinder 28.

The first piston 2 is placed in the first cylinder 24.
The first working chamber 32 is limited by 6 and the first working chamber 3
A second return spring 34, which constantly elastically presses the first piston 26 toward the valve member 16 side, is contracted in the position 2. In addition, a second working medium, for example, compressed air is supplied to the upper working wall of the upper housing 12a, or compressed air in the first working chamber 32 is discharged to the outside air.
A supply / discharge port 36 is provided. A first stopper ring 38 is screwed into the opening end of the first piston 26 on the valve member 16 side, and the stopper ring 38 and an annular contact surface 40 formed on the upper end surface of the lower housing 12b. In cooperation with each other, the displacement amount L _{2 of} the first piston 26 toward the valve member 16 side is limited.

The second piston 3 is placed in the second cylinder 28.
The second working chamber 42 is limited by 0, and the second working chamber 4 is
A second return spring 44, which constantly elastically presses the second piston 30 toward the valve member 16 side, is contracted in the position 2. In addition, a third piston 30 is opened inside the second piston 30 substantially coaxially with the valve stem 18 and toward the valve member 16 side.
A cylinder 46 is formed, and in the third cylinder 46,
The third piston 48 is fitted so as to be slidable in the axial direction of the valve stem.

The third piston 4 is placed in the third cylinder 46.
The third working chamber 50 is limited by 8 and the third working chamber 5 is
At 0, a third return spring 52 that elastically presses the third piston 48 toward the valve member 16 side is contracted, and the lower end surface of the third piston 48 is fixed by the spring 52 to the upper end surface of the valve stem 18. Is always pressed against. Further, a second stopper ring 54 is screwed into the opening end of the second piston 30 on the valve member 16 side, and the third piston 48 of the third piston 48 is at the fully closed position of the valve member 16 shown in FIG. A gap L ₁ is set between the lower end surface and the second stopper ring 54, and this gap L ₁ is an allowable displacement amount or stroke of the third piston 48 with respect to the third cylinder 46. On the other hand, the valve member 16 of the second piston 30
Between the lower end surface of the second stopper ring 54 screwed into the open end of the first piston 26 and the upper end surface of the first stopper ring 38 screwed into the open end of the first piston 26 on the valve member 16 side,
In the fully closed state of the valve member 16 shown in FIG. 1, the gap L ₃ is set. The gap L ₃ is an allowable displacement amount or stroke of the second piston 30 with respect to the second cylinder 28.

Compressed air as a working medium is supplied to and discharged from the third working chamber 50 through a first passage 56 and a second working chamber through a second passage 58 on the side wall of the upper housing 12a. A first supply / discharge port 60 for supplying / discharging to / from 42 is provided. The first passage 50 includes the first piston 26.
Of the third working chamber 50 at all times through an annular groove 64 recessed in the peripheral wall and a communication hole 66 penetrating the peripheral wall.
The second passage 58 is closed by the shoulder portion 26 ′ of the first piston 26 when the valve member 16 is in the fully closed position shown in FIG. 1, so that the first piston 26 moves toward the valve member 16 side. It is formed so as to communicate with the second working chamber 42 by being displaced.

A spring retainer 70 is attached to an upper portion of the valve stem 18 of the valve member 16 through a normal valve cotter 68, and a valve guide 72 or a valve guide 72 for slidably inserting the spring retainer 70 and the valve stem 18 is provided. A valve spring 74 is contracted between the valve retainer and the spring retainer fitted on the valve guide 72.
The valve member 16 is urged by the fully closed position shown in FIG.

FIG. 1 shows a state in which compressed air as a working medium is not supplied to either the first supply / discharge port 60 or the second supply / discharge port 36, and all the components are in the rest position. At this time, the valve member 16 is fully closed by the valve spring 74 having a large spring constant, the third piston 48 is pressed against the top surface of the valve stem 18 by the third return spring 52, and the second piston 30 is also closed. The upper end surface is in contact with the upper end surface of the second cylinder 28 in the first piston 26. Further, the first piston 26 is
It is pushed by the return spring 44 and its shoulder 2
6'abuts on the step portion 12a 'of the upper housing 12a.

In the fully closed position of the valve member 16, that is, in the rest position of the actuator 20, as already described,
The allowable displacement amount or setting stroke of the first piston 26 in the valve member 16 direction is L ₂ , and the allowable displacement amount or setting stroke of the second piston 30 with respect to the first piston 26 in the valve member 16 direction is L ₃ , or the second stroke. The allowable displacement amount or set stroke of the third piston 48 in the valve member 16 direction with respect to the piston 30 is L ₁ . The first piston 26
The setting stroke L ₂ of the valve stem 1 of the first stopper ring 38 changes the thickness of the shim 76 interposed between the upper housing 12a and the lower housing 12b.
It can be appropriately set by changing the thickness in the eight-axis direction, and similarly, the setting strokes L ₃ and L _{2 of} the second piston 30 and the third piston 48 are also the housing which is a main member of the actuator 20 and each. Pistons 26,3
By changing the thickness or dimension of the first and second stopper rings 38 and 54 in the axial direction of the valve stem, and the screwing position without changing the basic dimensions of 0 and 48,
It can be changed appropriately.

In the EGR control valve 10 having the above structure, as an example, the allowable displacement amount or the set stroke L ₂ of the first to third pistons 26, 30 and 48 is 4 mm, L.
The operation mode of the actuator 20 will be described for the case where _{3 is set} to 5 mm and L ₁ is set to 1 mm. (Note that, in the operation explanatory views of FIGS. 2 to 4, the first to third return springs 34, 44, and 52 are not shown in order to avoid excessive congestion in the drawings.)

First, FIG. 2 shows a state in which the second supply / discharge port 36 is opened to the atmosphere and compressed air as a working medium is supplied to the first supply / discharge port 60. The compressed air supplied to the first supply / discharge port 60 enters the third working chamber 50 via the first passage 56, the annular groove 64, and the communication hole 66, and causes the third piston 48 to resist the valve spring 74 and to the second. Stopper ring 5
The valve member 16 is displaced to a position where it abuts the valve member 4. The displacement L ₁ = 1 mm of the third piston 48 becomes the first opening of the valve member 16, and the valve opening becomes 1 mm. As a result, the pressure difference between the upstream side and the downstream side of the valve member 16 and the valve opening degree L ₁ = 1.
An amount of exhaust gas corresponding to mm is supplied from the exhaust gas passage 14 to the intake system of the engine.

Next, FIG. 3 shows a case where the first supply / discharge port is open to the atmosphere and compressed air is supplied to the second supply / discharge port 36. When the compressed air flows into the first working chamber 32 in the first cylinder 24, the first stopper ring 38 screwed to the lower end of the first piston 26 contacts the annular contact surface 40 of the lower housing 12b. It is displaced until it comes into contact, and the displacement amount L ₂ is 4 mm. Due to the above displacement of the first piston 26, the second piston 30 and the third piston 48 are interlocked and displaced together, and the valve member 16 causes the second opening L ₂ via the valve stem 18 that abuts against the third piston 48. = 4 mm
The exhaust gas is opened only by an amount corresponding to the pressure difference between the upstream side and the downstream side of the valve member 16 and the opening L ₂ = 4 mm.
4 is supplied to the intake system of the engine. At this time, the second passage 58 is opened by the displacement of the first piston 26, but since the first supply / discharge port 60 communicates with the atmosphere,
The second working chamber 42 only communicates with the atmosphere, and does not affect the displacement of the first to third pistons 26, 30 and 48.

Further, FIG. 4 shows a case where compressed air is supplied to both the first supply / discharge port 60 and the second supply / discharge port 36. When the compressed air flows into the first working chamber 32 from the second supply / discharge port 36, the first piston 26 is
Just as described with reference to FIG. 3 above, the set displacement amount L ₂ = 4
The valve member 16 is displaced by mm. Since the second passage 58 is opened by the downward displacement of the first piston 26, the compressed air supplied to the first supply / discharge port 60 flows into the second working chamber 42 from the second passage 58 and the first passage 56. Also flows into the third working chamber 50 through the annular groove 64 and the communication hole 66. Due to the pressure of the compressed air flowing into the second working chamber 42, the second piston 30 is displaced until the second stopper ring 54 screwed at the lower end thereof comes into contact with the first stopper ring 38, and this displacement amount L ₃ = It is 5 mm. On the other hand, as the compressed air flows into the third working chamber 50, the third piston 48 moves to the second stopper ring 5 as described with reference to FIG.
It is displaced until it comes into contact with _No. 4, and the displacement amount is L ₁ = 1 mm. As a result of the above, the valve member 16 passes through the valve stem 18 that is in contact with the third piston 48, and the total opening degree L ₁ + L
₂ + L ₃ = 10 mm to open the valve member 16
Of the exhaust gas in an amount corresponding to the pressure difference between the upstream side and the downstream side of the exhaust gas and the total amount or the third opening degree (10 mm).
Is supplied to the intake system of the engine.

As described above, in the EGR control valve shown in FIG. 1, first, the compressed air is supplied to the first supply / discharge port 60 and the second supply / discharge port 36 is opened to the atmosphere, so that the valve member is opened. 16 is the lift or opening L ₁ of the first stage, that is, 1 mm is opened in this example, and then compressed air is supplied to the second supply / discharge port 36 and the first supply / discharge port 60 is opened to the atmosphere. By opening the valve member 16 at the second stage lift or opening L ₂ , ie, 4 mm in this example, and further supplying compressed air to both the first supply / discharge port 60 and the second supply / discharge port 36, The valve member 16 opens the third opening L ₁ + L ₂ + L ₃ , which is 10 mm in this example.

As a result, the minimum lift or opening L ₁ and the intermediate lift or opening L ₂ and the sufficiently large third lift or opening L ₁ + L ₂ + L ₃ can be easily obtained. Further, as described above, by appropriately selecting the thickness or the screwing position of the shim 76, the first and second stopper rings 38 and 54, it is possible to widely set three kinds of valve lifts or opening degrees. Therefore, the valve opening can be set with a wide degree of freedom.

FIG. 5 is a schematic configuration diagram showing the overall configuration of a vehicle engine including the EGR control valve 10. In the figure, reference numeral 78 conceptually shows a 6-cylinder diesel engine for vehicles such as trucks, 80 is an intake pipe including an intake manifold of the engine 78, 82 is an air cleaner provided at the air intake of the intake pipe, and 84 is the above An exhaust pipe including an exhaust manifold of the engine, 86 is an EGR passage for extracting a part of the exhaust gas flowing in the exhaust pipe 84 and returning it to the intake pipe 80, in which the EGR control valve 10 is interposed. It is equipped.

The first supply / discharge port 60 of the EGR control valve 10
Is connected to the compressed air source 90 via the first electromagnetic three-way valve 88, and the second supply / discharge port 36 is connected to the compressed air source 90 via the second electromagnetic three-way valve 92. The first and second
The electromagnetic three-way valves 88 and 92 receive a drive signal by receiving an accelerator opening signal Ac indicating the accelerator pedal depression amount of the vehicle, a rotation speed signal Ne indicating the engine speed, and a cooling water temperature signal Tw indicating the cooling water temperature of the engine. Is controlled by a control unit or control device 94 that causes

The control unit or control device 9
An example of the control map stored in No. 4 is shown in FIG. In this map, the vertical axis represents the torque Tq, and the horizontal axis represents the engine speed Ne.
It shows the set lift or the opening degree of the valve member 16 in various operating states after w is 60 ° C. or higher, that is, after completion of warm-up. The valve opening types are categorized on the right side of the drawing for easy understanding, and the engine 7
When 8 is operating in the first operating region X where the engine speed is higher than the idle speed No but lower than the preset middle speed N ₁ and in the middle speed range, and the load is equal to or lower than the medium load, The control unit 94 controls the first and second electromagnetic three-way valves 88.
And 92 are urged to supply the compressed air from the compressed air source 90 to the first and second supply / discharge ports 60 and 36, and the valve member 16 has the above-described third opening degree (L ₁ + L ₂ + L ₃ ). And the exhaust gas from the exhaust pipe 84 is returned to the intake pipe 80 through the EGR passage 86 and the valve member 16 having the maximum opening.

In this engine operating region X, the exhaust pipe 84
The amount of exhaust gas flowing through is relatively low and the pressure is low,
On the other hand, since the negative pressure of the intake pipe 80 is small, it is essentially difficult to recirculate the exhaust gas to the intake pipe 80, and as described above, the valve member 16 is opened to the maximum opening (L ₁ + L ₂₎ of the third stage. +
Opening to L ₃ ) has the advantage of ensuring the required exhaust gas recirculation amount. As a result, required engine performance such as output and fuel consumption is secured while effectively reducing NO _x in the exhaust gas.

Next, when the engine 78 is operating in the second operating region Y in which the engine speed is equal to or higher than the set intermediate speed rotation speed N ₁ and is equal to or lower than the maximum rotation speed N _{3 and is} equal to or lower than a preset middle load. The control unit 94 urges only the second electromagnetic three-way valve 92 to supply compressed air from the compressed air source 90 to the second supply / discharge port 36, and the first supply / discharge port 60 communicates with the atmosphere. It Therefore, as described above, the valve member 16 has the intermediate second lift or opening L ₂ . In the engine operating region Y, the engine speed Ne is sufficiently high, the negative pressure of the intake pipe 80 is large, and the exhaust gas pressure of the exhaust pipe 84 is relatively high. Therefore, the valve member 16 with the _second opening L ₂ is set. An appropriate amount of exhaust gas is recirculated to the intake system of the engine 78 through the.

Further, when the engine 78 is operating in the third operating region Z having a higher load than the first and second operating regions X and Y and having a preset high-speed rotational speed N ₄ rotational speed, The first electromagnetic three-way valve 8 by the unit 94
8 is urged to supply compressed air from the compressed air source 90 only to the first supply / discharge port 60, and the valve member 16 has the minimum lift or opening L ₁ as described above. In this operating range Z, in the rotational speed range of medium speed or higher, the exhaust gas pressure in the exhaust pipe 84 is relatively high, and the negative pressure in the intake pipe 80 is sufficiently high, so the opening degree of the valve member 16 is small. The exhaust gas is sufficiently recirculated, and in the low rotational speed region of this region Z, the intake air amount is relatively small, but the fuel supply amount is relatively large. Therefore, if excessive exhaust gas recirculation is performed, smoke will be generated. Since it deteriorates, it is appropriate to set the opening degree of the valve member 16 to the minimum opening degree L _{1 in} order to prevent this.

Further, the first to third operating regions X,
In the operating regions other than Y and Z, that is, in the white region in FIG. 6, exhaust gas recirculation is not necessary from the viewpoint of engine performance such as output, fuel consumption, and the need to reduce NO _x in the exhaust gas. The control unit 94 deactivates both the first and second electromagnetic three-way valves 88 and 92, and the first and second supply / discharge ports 60 and 36 of the EGR control valve 10 are both open to the atmosphere, and thus shown in FIG. As described above, the valve member 16 is fully closed. It should be noted that a plurality of inclined vertical lines or polygonal lines indicated by adding% in FIG. 6 indicate the accelerator opening Ac, respectively.

The control unit or control device 9
The four operating modes are shown in the chart of FIG. When the program starts, in step S ₁ , the coolant temperature Tw indicating the operating state of the engine 78 and the accelerator opening A
c and the engine speed Ne are read respectively. In step _{S 2,} the engine coolant temperature Tw is the set water temperature To
It is determined whether the temperature is higher than (for example, 60 ° C.). If NO, since warming up of the engine 78 has not ended, it is inappropriate to perform exhaust gas recirculation (because cold start becomes difficult or smoke becomes worse).
EGR is not performed as shown in step S ₄ .

[0039] In step _{S 2,} it is determined that YES (warm-up completion), at step _{S 5,} the increase rate ΔAc accelerator opening Ac is checked whether settings increase ΔAco smaller. If the accelerator opening increase rate ΔAc is set increase rate is smaller than YES, that is in a normal running state rapid acceleration is not performed, the program proceeds to S _6, the valve member by the two-dimensional map shown in FIG. 6 16
Required lift or opening L ₁ , L ₂ or (L ₁ + L ₂
+ L ₃ ) or fully closed, and in step S ₇ , the electromagnetic three-way valves 88 and 92 are commanded to be energized or deenergized, and the opening degree of the valve member 16 is controlled as described above. . Further, in step S _5, the case of NO, that is if the rapid acceleration, tend to smoke increases, stop refluxing the exhaust gas to prevent deterioration of smoke. Incidentally, the accelerator opening degree A at step _{S 5}
Instead of checking the rate of change of c, the difference between the real-time accelerator opening and the accelerator opening before the set minute time and its increase / decrease are checked, and the set accelerator opening difference (increasing side)
You may make it compared with.

Next, in the second embodiment of the present invention shown in FIG. 9, a fourth working chamber 96 for accommodating the upper portion of the valve stem 18 is provided by the upper housing 12a and the lower housing 12b. A normal valve guide seal 98 is provided on top of the valve guide 72 to seal the working chamber 96.
Is attached. Also, on the side wall of the lower housing 12b,
Third supply / discharge port 100 communicating with the fourth working chamber 96
And the supply / discharge port 100 is provided with a third electromagnetic three-way valve 10 as shown in the schematic configuration diagram of FIG.
It is connected via 2 to a working medium source, in this case a compressed air source 90. As is apparent from FIGS. 9 and 10, the configuration other than the above is substantially the same as that of the first embodiment.

In the flowchart of FIG. 8 for explaining the operation mode of the control unit or the control device 94 in relation to the first embodiment, the valve member 1 of the EGR control valve 10 is shown.
When 6 is traveling at any one of the first to third stage lifts or the openings L ₁ , L ₂ or (L ₁ + L ₂ + L ₃ ), the accelerator pedal is suddenly depressed, and step S _Four
, The accelerator opening increase rate ΔAc is equal to the set increase rate ΔAc.
In the case of NO equal to or higher than Aco, that is, in the case of rapid acceleration, step S ₈ indicated by the alternate long and short dash line in the chart.
As described above, the third electromagnetic three-way valve 102 is energized based on the drive signal of the control unit 94, and the compressed air source 9
Compressed air is supplied from 0 to the fourth working chamber 96. As a result, it is both de-energized the EGR stop i.e. the first and second three-way solenoid valves 88 and 92 in step S _5, when they are fully closed as the valve member 16 is shown by a valve spring 74 in FIG. 9 The compressed air pressure in the fourth working chamber 96 positively urges the third piston 48 upward in the drawing, that is, in the direction of closing the valve member 16. As a result, in the diagram of FIG.
In the first embodiment described above, as indicated by the dotted line α ₁ in the figure, the valve member 16 has the opening degrees L ₁ , L ₂ or (L ₁
+ L ₂ + L ₃ ), it is fully closed with a relatively large time delay (EGR stop state) at the time of sudden acceleration, so the smoke concentration as shown by the dotted line in the figure. While β ₁ temporarily deteriorates considerably, in the second embodiment, as shown by solid lines α ₂ and β ₂ in the figure, the time required to fully close the valve member 16 is shown. Is shortened, and the deterioration of the smoke concentration is greatly reduced. As shown in the figure, the urging time of the third electromagnetic three-way valve 102 is preferably a time until the valve member 16 is fully closed or a time slightly longer than that.

In the first and second embodiments described above, a poppet valve is illustrated as the valve member 16, but a butterfly valve widely used in exhaust brake devices such as trucks can be used. . In the case of a butterfly valve, a drive link or arm is provided on the valve shaft so as to project, and the drive link or arm is rotated via a piston rod fixed to the third piston 48 or a transmission link connected to the piston. Then, the valve opening, that is, the rotating portion of the valve shaft may be controlled. Further, it is obvious that the present invention is not limited to the illustrated EGR control valve, but can be widely applied to various valve devices that require three stages of valve lift or opening.

[0043]

As described above, the multi-stage opening valve device according to the present invention includes a valve member which is interposed in the fluid passage and which controls the flow rate of the fluid by setting the opening in multiple stages. A first piston provided in a housing and slidably fitted in a first cylinder, a second cylinder formed substantially coaxially in the first piston, and freely slidable in the second cylinder A second piston, a third cylinder formed substantially coaxially in the second piston, and a third cylinder slidably fitted in the third cylinder and operatively connected to the valve member. The third
A piston, an elastic device connected to the valve member for constantly urging the valve member in the closing direction, and provided on the housing,
By supplying hydraulic medium to the third working chamber formed within said second cylinder, first only the third piston is displaced in the opening direction to open the valve member by the first opening L ₁ 1 Supply and discharge ports and a first working chamber provided in the housing and formed in the first cylinder to displace the first piston in the valve opening direction, and the second piston and By supplying the working medium to both the first supply / discharge port and the second supply / discharge port, the second supply / discharge port opening the valve member by the second opening L ₂ via the third piston To the third working chamber, the working medium is supplied to the first piston, the second piston, and the third piston.
The piston is displaced in the valve opening direction, and the first and second openings L
₁ and L ₂ and the third opening L ₃ of the second piston is added, the valve member is configured to be opened by a total opening L ₁ + L ₂ + L ₃ ; There is an advantage that the intermediate valve lift or opening can be widely selected, and the set valve lift or opening can be accurately and easily achieved. Particularly, the multistage opening suitable for the EGR control valve for vehicles is provided. A degree valve device can be provided, which is industrially beneficial.

In the housing, there is a first passage communicating the first supply / discharge port with the third working chamber in the second piston, and the first supply / discharge port and the first passage in the first piston. A second passage communicating with the two working chambers is provided, and the second passage is closed by the first piston when the working medium is supplied only to the first supply / discharge port. When the working medium is supplied to the second supply / discharge port, the structure is such that it is opened by the displacement of the first piston, so that the structure of the valve member actuating actuator can be made small and compact. There are advantages. Further, a fourth working chamber facing the pressure receiving surface opposite to the pressure receiving surface facing the third working chamber of the third piston is provided in the housing, and the working medium is supplied to and discharged from the fourth working chamber. By providing the third supply / discharge port, the valve closing speed can be positively increased, and when it is applied to, for example, an EGR control valve, there is an effect that the generation of smoke during sudden acceleration can be reduced. In addition, the multi-stage opening valve device is particularly suitable for being applied to an EGR control valve in an engine of a vehicle or the like, and in this case, the engine has a rotational speed equal to or lower than a preset medium speed rotational speed, and When operating in the preset first operation region of medium or lower load, the working medium is supplied to the first and second supply / discharge ports, and the first to third pistons are all displaced in the valve opening direction. The valve member is opened by L ₁ + L ₂ + L ₃ which is the sum of the first to third opening degrees,
Further, when the engine is operating at the above-mentioned set medium speed rotation speed and in the second operating region of a preset medium or lower load, the working medium is supplied only to the second supply / discharge port,
The first piston is displaced in the valve opening direction, the valve member is opened by the second opening L ₂ via the second and third pistons, and the engine has a higher load than the first and second operating regions. When operating in the third operating region of the rotational speed lower than the preset high speed rotational speed, the working medium is supplied to the first supply / discharge port, and only the third piston is displaced in the valve opening direction. The valve member is configured to be opened by the first opening L ₁ , and when the engine is operating in an operating region other than the first to third operating regions, and during rapid acceleration of the engine. When the engine cooling water temperature is equal to or lower than the set temperature, the working medium is not supplied to any of the first and second supply / discharge ports, and the valve member is held in the closed position by the elastic device. By configuring
Appropriately EG according to all operating conditions of the vehicle engine
The opening of the R control valve is controlled, and the exhaust gas performance, especially NO _x
And, there is an advantage that the smoke performance can be effectively improved. Further, compressed air is used as a valve opening control actuator working medium of the multi-stage opening valve device, and its supply / discharge is performed by an electromagnetic three-way valve, so that a vehicle such as a truck,
The compressed air source, which is widely installed as a supply source of the brake operating medium, is used as it is, and it is not necessary to provide additional equipment. Therefore, there is an advantage that manufacturing and running costs are reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an EGR control valve showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of the valve device shown in FIG. 1 when the valve opening degree is minimum.

FIG. 3 is a cross-sectional view of a main part of the valve device shown in FIG. 1 when the valve opening degree is an intermediate opening degree.

FIG. 4 is a cross-sectional view of the main parts of the valve device shown in FIG. 1 when the valve opening is maximum.

5 is a schematic configuration diagram of an entire engine including the EGR control valve shown in FIG.

6 is a diagram showing an example of a control map stored in a control unit 94 in FIG.

7 is a diagram showing an operating mode of the EGR control valve shown in FIGS. 1 and 9. FIG.

FIG. 8 is a flowchart showing the operation of the control unit 94 in FIGS. 5 and 10.

FIG. 9 is a cross-sectional view of an EGR control valve showing a second embodiment of the present invention.

10 is a schematic configuration diagram of an entire engine including the EGR control valve shown in FIG.

FIG. 11 is a cross-sectional view of a conventionally known homogeneous EGR control valve.

[Explanation of symbols]

10 ... EGR control valve, 12 ... Housing, 14 ... Exhaust gas passage, 16 ... Valve member, 18 ... Valve stem, 20 ... Actuator, 24 ... First cylinder, 26 ... First piston,
28 ... 2nd cylinder, 30 ... 2nd piston, 32 ... 1st
Working chamber, 36 ... Second supply / discharge port, 38 ... First stopper ring, 42 ... Second working chamber, 46 ... Third cylinder, 48 ...
3rd piston, 50 ... 3rd working chamber, 54 ... 2nd stopper ring, 56 ... 1st passage, 58 ... 2nd passage, 60 ... 2nd
Supply / exhaust port, 74 ... Valve spring, 78 ... Diesel engine, 80 ... Intake pipe, 84 ... Exhaust pipe, 86 ... EGR passage, 88 ... First electromagnetic three-way valve, 90 ... Compressed air source (working medium source), 92 ... Second electromagnetic three-way valve, 94 ... Control unit, 96 ... Fourth working chamber, 100 ... Third supply / discharge port.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazutoshi Mori 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation

Claims (9)

[Claims] 1. A valve member, which is interposed in a fluid passage and controls the flow rate of the fluid by setting its opening in multiple stages,
A first piston slidably fitted in a first cylinder provided in the housing, a second cylinder formed substantially coaxially in the first piston, and sliding in the second cylinder A freely mounted second piston, a third cylinder formed substantially coaxially within the second piston, and a slidably mounted inside the third cylinder and operatively connected to the valve member. A third piston, an elastic device that is connected to the valve member and normally urges the valve member in a closing direction, and a working medium that is provided in the housing and is provided in a third working chamber formed in the second cylinder. Is provided to displace only the third piston in the valve opening direction to open the valve member by the first opening L ₁ , and the first cylinder provided in the housing. Supplying a working medium to a first working chamber formed therein. And a second supply / discharge port for displacing the first piston in the valve opening direction to open the valve member by the second opening L ₂ via the second piston and the third piston, and the first supply / discharge. By supplying the working medium to both the port and the second supply / discharge port, the working medium is supplied to the first to third working chambers and the first piston, the second piston and the third piston are displaced in the valve opening direction. And the valve member is opened by a total opening amount L ₁ + L ₂ + L _{3 obtained} by adding the third opening amount L ₃ of the second piston to the _first and second opening amounts L ₁ and L ₂ . A multi-stage opening valve device characterized in that 2. A first communication port for communicating between the first supply / discharge port and the third working chamber in the second piston in the housing.
A passage and a second passage communicating the first supply / discharge port with the second working chamber in the first piston are provided, and the second passage supplies the working medium only to the first supply / discharge port. When it is being closed, it is blocked by the first viston,
2. The multi-stage opening valve device according to claim 1, wherein when the working medium is supplied to the second supply / discharge port, it is configured to be opened by the displacement of the first piston. 3. A fourth working chamber facing the pressure receiving surface opposite to the pressure receiving surface facing the third working chamber of the third piston is provided in the housing, and a working medium is placed in the fourth working chamber. The multi-stage opening valve device according to claim 1, further comprising a third supply / discharge port for supplying / discharging. 4. The EGR passage for supplying a part of the exhaust gas of the engine to an intake system of the engine, and the valve member for controlling the flow rate of the exhaust gas supplied to the intake system by the valve member. It is a control valve, It is characterized by the above-mentioned.
Alternatively, the multistage opening valve device according to claim 3. 5. The working medium supplied to the first and second supply / discharge ports is compressed air, and the first and second supply / discharge ports are compressed via the first and second electromagnetic three-way valves, respectively. The multistage opening valve device according to claim 1 or 4, wherein the multistage opening valve device is connected to an air source. 6. The working medium supplied to the third supply / discharge port is compressed air, and the third supply / discharge port is connected to a compressed air source via a third electromagnetic three-way valve. The multistage opening valve device according to claim 3. 7. The first and second feed rates are set when the engine is operating at a rotational speed equal to or lower than a preset medium speed rotational speed and in a first operating range of a preset medium or lower load. The working medium is supplied to the discharge port, the first to third pistons are all displaced in the valve opening direction, and the valve members move to the first to third positions.
When the engine is operated by L ₁ + L ₂ + L ₃ with the opening added, and the engine is operating in the second operating range of the set medium speed and the preset medium or lower load, the second The working medium is supplied only to the supply / discharge port, the first piston is displaced in the valve opening direction, the valve member is opened by the second opening L ₂ via the second and third pistons, and the engine is When operating in a third operating region having a higher load than the first and second operating regions and a preset rotational speed lower than or equal to a high speed rotational speed, the working medium is supplied to the first supply / discharge port, 5. The multistage opening valve device according to claim 4, wherein only the third piston is displaced in the valve opening direction and the valve member is opened by the first opening L ₁ . 8. When the engine is operating in an operating region other than the first to third operating regions, during rapid acceleration of the engine, and when the cooling water temperature of the engine is below a preset temperature, The multistage opening according to claim 7, wherein the working medium is not supplied to either the first or second supply / discharge port, and the valve member is held in the closed position by the elastic device. Valve device. 9. When the valve member is closed from the open state, the working medium is supplied to the third supply / discharge port, and the third piston is biased in the valve member closing direction. The multistage opening valve device according to claim 7 or 8, characterized in that.