JPH04255558A - Fluid controlling valve device - Google Patents

Abstract

PURPOSE:To prevent air from its waste consumption and a high pressure chamber from being reduced so as to stably actuate a valve unit by impeding air(operating fluid) in the high pressure chamber(operating pressure chamber) from flowing into a low pressure chamber(atmosphere opening chamber). CONSTITUTION:When a valve unit 26 is opened by pressing down a piston 20, a lower end of the piston 20 is brought into close contact with a seal member 32 to hold air-tightness inside/outside a low pressure chamber 22b, so that compressed air, supplied into a high pressure chamber 22a, is prevented from being released to the atmosphere by passing through a clearance between a cylinder 16 and the piston 20 to flow into the low pressure chamber 22b.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid control valve device such as an exhaust gas recirculation valve installed in an exhaust system of an internal combustion engine.

0002

[Prior Art] This type of exhaust gas recirculation device recirculates a part of the exhaust gas to the intake system to lower the combustion temperature in the cylinder, and reduces the combustion temperature in the cylinder to reduce the combustion temperature in the cylinder. There is an EGR valve (see, for example, Japanese Utility Model Application Publication No. 2-43451) that is designed to reduce the amount of nitrogen oxides emitted.

Some of these EGR valves employ a piston type actuator for driving a valve body for opening and closing a recirculation port. In general, a piston type actuator has a high pressure chamber (operating pressure chamber) at the head side of the piston that slides inside the cylinder, and a low pressure chamber (atmosphere open chamber) at the bottom side, and compressed air is supplied to the high pressure chamber. This operates the piston and opens and closes the valve body linked to the piston.

[0004] In this piston type actuator, compressed air supplied to the high pressure chamber flows into the low pressure chamber side through a small gap between the sliding part between the cylinder and the piston, and communicates with the outside air that opens into the low pressure chamber. There is a problem with the air being discharged to the outside through the air holes. In particular, EGR valves for large diesel engines have high back pressure on the exhaust side, so it is necessary to send enough high-pressure air into the high-pressure chamber to overcome the back pressure and open the valve element. The amount of leakage to the room side also increases.

[0005] When this happens, the pressure in the high-pressure chamber is reduced and the lift amount when the valve opens changes, causing an error in the amount of exhaust gas recirculation and causing more air from the compressed air source to be consumed than necessary. , mechanical losses are also large, such as the need to operate the compressor frequently.

[0006] In order to solve this problem, it may be possible to insert a sealing member such as an O-ring in the sliding part between the cylinder and the piston, but this would reduce the sliding friction between the cylinder and the piston. The increased resistance not only deteriorates the responsiveness when opening and closing the valve, but also causes new problems such as the sealing performance being impaired due to wear of the sealing member and the sealing member having to be replaced at an early stage.

[0007]

[Problems to be Solved by the Invention] The present invention has been made to solve the above problems, and its purpose is to prevent the air in the high pressure chamber from flowing into the low pressure chamber. Another object of the present invention is to provide a fluid control valve device which prevents wasteful consumption of compressed air and depressurization of a high pressure chamber and stably operates a valve body.

[0008]

[Means for Solving the Problems] The above object is to provide fluid flow between the piston and the air-opening chamber, which are partitioned by a piston slidably provided in a cylinder chamber, by a pressure difference between a working pressure chamber and an atmospheric release chamber. In a fluid control valve device equipped with a piston-type actuator that moves a valve body for opening and closing a port, either one of the piston end on the atmosphere open chamber side and the opposing part in the cylinder chamber opposite thereto. when the valve body is open,
This can be achieved by providing a seal member that blocks the flow of working fluid between the working pressure chamber side and the atmosphere open chamber side.

[0009]

[Operation] When the piston moves in the direction of opening the valve body,
The sealing member completely maintains airtightness between the outside of the piston and the atmosphere-opening chamber inside, so the fluid (compressed air) supplied into the working pressure chamber passes through the gap between the cylinder and the piston and is released to the atmosphere. This prevents it from entering the room and being released into the atmosphere.

[0010]Therefore, there is no possibility that the fluid will be wasted or the pressure in the working pressure chamber will be reduced.

[0011]

Embodiments Hereinafter, embodiments in which the present invention is applied to an EGR valve will be described based on the drawings. FIG. 1 shows a first embodiment of an EGR valve (1) used in a large diesel engine, and is used by being attached to an engine as shown in FIG. 6, for example.

That is, the exhaust manifolds (2) (2) installed on both sides of the multi-cylinder diesel engine (E), which is generally V-shaped when viewed from the front, are equipped with exhaust pipes (3) at the rear ends thereof.
(3) are connected to each other, and on the inner surface of the proximal end of both exhaust pipes (3), there is a flange part (4a) (see Fig. 1) that is perpendicular to the exhaust pipe (3) and opens upward in the middle part. A bypass pipe (4) is connected thereto.

[0013] The EGR valve (1) has the above-mentioned flange portion (
4a) is mounted vertically on top and its port outlet end is connected via an inlet pipe (5) to a communication pipe (7) which brings both intake pipes (6) (6) into communication with each other.

Next, the details of the EGR valve (1) are shown in FIG.
Explain with reference to. (8) is a cast body that has an elbow-shaped recirculation port (9) with the exhaust gas inlet side opening downward and the outlet side opening laterally (forward in Figure 6). The end has flanges (10) (1
0) is integrally formed. (11) is the body (
8) is a heat dissipation fin formed around.

At the upper end of the body (8), there is a relatively large circular mounting seat (12) that extends horizontally laterally from the body (8) and acts as a heat shield and a heat sink. The mounting seat (12) is integrally molded with a required distance from the middle part of the body (8), and the mounting seat (12) has a plurality of thin plate-like ribs (13) extending downward from the lower surface thereof toward the middle part of the body (8). reinforced by.

A plurality of projections (14) with smooth upper surfaces are integrally molded on the upper surface of the mounting seat (12), and a through hole (15a) of a required size is provided at the center of each projection (14). , a spring receiver (15) having approximately the same diameter as the mounting seat (12), and a capped cylindrical cylinder (16) of the actuator (A) on the upper surface of the spring receiver (15). Insert the bolt (1
7) is integrally fixed by screwing it in.

As a result, a slight gap (18) communicating with the outside air is formed between the upper surface of the mounting seat (12) and the lower surface of the spring receiver (15). (19) is a packing with low thermal conductivity that is interposed between the spring receiver (15) and the cylinder (16).

Inside the cylinder (16) is a cylindrical piston (20) whose top surface is closed and which is in close contact with a thick walled part (16a) formed at the middle part of the inner circumferential surface of the cylinder (16), and is slidable up and down. It is inserted as a. A pipe (21) for supplying air from a compressed air source (not shown) such as a compressor into the cylinder (16) is connected to the upper surface of the cylinder (16).

[0019] The lower surface of the cylinder (16) and the piston (20
) is a high pressure chamber (operating pressure chamber) (22a).
Furthermore, the empty chamber surrounded by the piston (20) is a low pressure chamber (atmosphere open chamber) (22b). (23) is a compression coil spring compressed within the high pressure chamber (22a) and constantly presses the piston (20) downward.

A valve guide (24) is press-fitted into the center of the body (8), and its upper end is connected to the spring receiver (1).
The piston (2) passes through the central through hole (15a) of the piston (2).
It is located at the bottom of 0).

[0021] The through hole (15a) and the valve guide (24
) and the outer circumferential surface of the air hole (
25). A shaft (26a) of a mushroom-shaped valve body (26) is slidably inserted into the valve guide (24), and a retainer (27) is fitted to the shaft end located within the piston (20). ) has an annular groove (2
A pair of cotters (28) (28) fitted on the outside of the cotters (28) (6b) are fitted inside, thereby fixing them.

[0022] The lower surface of the retainer (27) and the spring receiver (15)
) A return spring (compression coil spring) (29) is compressed between the upper surface of the spring and the upper surface of the spring. This allows the valve body (
26) is always biased upward, and under normal conditions, the reflux port (9) is in close contact with the valve seat (30) fitted to the lower end opening of the reflux port (9) by the umbrella portion (26c). Closed.

An annular groove (31) is formed on the upper surface of the spring receiver (15) facing the lower end surface of the piston (20), and this groove (31) is fitted with a seal made of elastic rubber or the like. The member (32) is fitted with its upper surface slightly protruding from the upper surface of the spring receiver (15).

When the piston (20) descends to the lower limit position, its lower end surface touches the seal member (3), as shown by the imaginary line.
2), the low pressure chamber (22b
) and a gap (33) formed around the lower part of the piston (20).

Normally, the inner bottom surface of the piston (20) comes into contact with the shaft end surface of the valve body (26) due to the biasing force of the compression coil spring (23) contracted within the high pressure chamber (22a). When the valve body (26) is closed, the piston (2
between the lower end of the valve body (26) and the sealing member (32).
) A required gap corresponding to the lift amount is formed.

Next, the operation of the above embodiment will be explained. When the engine (E) is in a medium-low speed and low load operating range and compressed air is forced into the high pressure chamber (22a) by the operation of a control device (not shown), the piston (20) and the valve body (26)
are pushed down together against the return spring (29), and the lower end of the piston (20) is pushed down against the seal member (3).
It stops when it comes into contact with 2).

As a result, the valve body (26) is opened, and the exhaust gas flowing into the bypass pipe (4) is directed to the recirculation port (9).
It passes through the introduction pipe (5) and is fed into each cylinder (not shown) of the engine from the communication pipe (7). the result,
The combustion state becomes slow, the combustion temperature is kept low, and the N
Ox emissions are reduced.

When the engine (E) enters a high-speed, high-load operating range, the control device operates again to stop the supply of compressed air, thereby reducing the valve body (26) and piston (20).
is returned by the return spring (29), and the reflux port (9) is automatically closed.

When the valve body (26) is open, the pressure inside the high pressure chamber (22a) becomes quite high due to the compressed air sent from the compressed air source.
The air inside flows into the low pressure chamber (22b) through a small gap between the sliding contact between the cylinder (16) and the piston (20), and attempts to flow out through the air hole (25).

However, the EGR valve of this first embodiment (
In 1), when the piston (20) is pushed down to the lower limit position and the valve body (26) is opened, the lower end of the piston (20) comes into close contact with the sealing member (32) and the low pressure chamber (22b ), air leakage from the gap between the cylinder (16) and the piston (20) will not flow into the low pressure chamber (22b).

[0031] As a result, problems such as excessive consumption of compressed air, depressurization of the high pressure chamber (22a), and change in the lift amount (opening degree) of the valve body (26) are eliminated. FIG. 2 shows a second embodiment of the present invention. In this embodiment, contrary to the first embodiment, a seal member (34) made of rubber or the like is provided around the entire lower end surface on the piston (20) side. is fixed.

FIG. 3 shows a third embodiment of the present invention, which is surrounded by a step (16b) formed on the inner peripheral surface of the lower part of the cylinder (16) and a spring receiver (15). A ring-shaped sealing member (36) is fitted into the recess (35), and the lower outer peripheral surface of the piston (20) is made into an upwardly tapered surface (20a), so that when the piston (20) descends, the ring-shaped seal member (36) The tapered surface (20a) is the sealing member (36)
It is arranged to be in close contact with the inner circumferential surface of.

FIG. 4 shows a fourth embodiment of the present invention, in which the piston (
A ring-shaped sealing member (38) is fitted inside the annular stepped groove (37) formed in the portion facing the lower end of the piston (20), and the lower inner circumferential surface of the piston (20) is tilted upward. When the piston (20) descends, the tapered surface (20b) becomes the sealing member (38).
It is arranged to be in close contact with the inner circumferential surface of.

FIG. 5 shows a fifth embodiment of the present invention, in which the piston (20) on the upper surface of the spring receiver (15)
A metal washer (40) with a smooth tapered surface at an angle of approximately 30° to 45° upward is fitted into a groove (39) formed in a portion facing the lower end of the piston (
The lower outer peripheral surface of the piston (20) is a smooth tapered surface (20c) with the same inclination angle as the tapered surface of the washer (40).
20), the tapered surfaces thereof are brought into close contact with each other when descending.

[0035] Also in the second to fifth embodiments,
In either case, when the piston (20) is lowered, airtightness inside and outside the piston (20) is maintained, so that the same effects as in the first embodiment described above can be achieved.

Furthermore, in the EGR valve (1) as described above, when the high-temperature exhaust gas passes through the recirculation port (9), a portion of it passes through the valve guide (24) and the valve body (26).
The exhaust gas that has flowed into the low pressure chamber (22b) through the gap in the shaft portion (26a) of
) or deteriorate the cylinder (16) and piston (20).
) is expected to have an adverse effect on the sliding parts.

However, E in the first to fifth embodiments above
In both GR valves, the airtightness of the inside and outside of the low pressure chamber (22b) is maintained, so there is no risk of the above-mentioned problem occurring. In addition to the EGR valve, the present invention also provides a waste gate valve for a turbocharger, an exhaust brake valve,
It can also be applied to exhaust switching valves, air bypass valves, supercharging pressure control valves, etc. that use air as the working fluid in the actuator section.

Further, the valve body is not limited to the above-mentioned poppet valve, but may also be applied to a butterfly valve, a shutter valve, or the like.

[0039]

According to the present invention, the compressed air (working fluid) supplied to the high pressure chamber (working pressure chamber) is completely prevented from flowing into the low pressure chamber (atmosphere open chamber). This prevents compressed air from being wasted and the high pressure chamber from being depressurized, thus ensuring stable operation of the valve body and providing highly reliable E.
A GR valve can be provided.

[Brief explanation of the drawing]

FIG. 1 is a central longitudinal sectional front view showing an example in which a first embodiment of the present invention is applied to an EGR valve.

FIG. 2 is an enlarged longitudinal cross-sectional view of a main part similarly showing a second embodiment.

FIG. 3 is an enlarged longitudinal cross-sectional view of the main parts showing the third embodiment.

FIG. 4 is an enlarged vertical cross-sectional view of a main part showing a fourth embodiment.

FIG. 5 is an enlarged vertical cross-sectional view of the main part showing the fifth embodiment.

FIG. 6 is a plan view schematically showing an example in which an EGR valve according to an embodiment of the present invention is installed in a large diesel engine.

[Explanation of symbols]

(1) EGR valve
(2) Exhaust manifold (3) Exhaust pipe
(4) Bypass pipe (4a) flange
(5) Introduction pipe (6)
intake pipe
(7) Communication pipe (8) Body
(9) Reflux port (10) Flange (1
1) Radiation fin (12) mounting seat
(12a) Boss part (13) Rib
(14) Protrusion (15) Spring receiver
(15a) Through hole (16) Cylinder (16
a) Thick wall part (18) gap
(19) Packing (20) Piston (2
0a) (20b) (20c) Tapered surface (21) Pipe
(22a) High pressure chamber (operating pressure chamber) (22b) Low pressure chamber (atmosphere open chamber)
(23) Compression coil spring (24) Valve guide
(25) Air hole (26) Valve body
(26a) Shaft (26
b) Annular groove
(26c) Umbrella (27) Retainer
(27a) Tapered hole (28
) cotta
(29) Return spring (30) Valve seat
(31) Concave groove (32) Seal member
(33) Gap (34) Seal member (35) Recess (36) Seal member
(37) Stepped groove (38) Seal member
(39) Concave groove (40)
washer
(A) Actuator

Claims (4)

[Claims] Claim 1: A valve body that opens and closes a fluid circulation port linked to the piston and the piston by a pressure difference between an operating pressure chamber and an atmospheric release chamber defined by a piston slidably provided in a cylinder chamber. In the fluid control valve device including a piston-type actuator configured to move the valve body, the valve body is opened at either one of the piston end portion on the side of the atmosphere-opening chamber and the opposing portion in the cylinder chamber facing the piston end portion. 1. A valve device for fluid control, characterized in that a sealing member is provided that blocks the flow of working fluid between a working pressure chamber side and an atmosphere open chamber side when the working pressure chamber side and the atmosphere open chamber side are in operation. 2. The fluid control valve device according to claim 1, wherein the sealing member is provided on the cylinder side outside the piston so as to be in sliding contact with the outer peripheral surface of the piston. 3. The fluid control valve device according to claim 1, wherein the seal member is provided on the inner cylinder side of the piston so as to be in sliding contact with the inner circumferential surface of the piston. 4. The fluid control valve device according to claim 1, wherein the seal member is a washer provided on the cylinder side so as to be in close contact with the end surface of the piston.