JPH0735125Y2 - Bellows type actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field) The present invention relates to, for example, a bellows used as an actuator for various control devices such as a valve for an exhaust gas recirculation device of an automobile (hereinafter referred to as an EGR valve) and a pressure regulator. Type actuator, and more particularly to an actuator using a resin bellows.

(Prior Art) A conventional EGR valve has a structure as shown in FIG. 5, for example. That is, the valve 100 is controlled to be opened and closed by using the negative pressure of the engine, and the rubber diaphragm 107 is used as an actuator for operating the valve 100.

In this actuator 101, the inside of the hollow of the actuator body 101, which is formed by the upper cup 105 and the lower cup 106 that are airtightly assembled into a hollow interior, is the diaphragm 1
It is divided into two chambers by 07, and a negative pressure is introduced into one chamber through the negative pressure introducing pipe 105a. The differential pressure between the two chambers causes the diaphragm 107 to reciprocate and actuate the valve element 108 attached to the diaphragm 107 to open and close the passage between the exhaust pipe port 103 and the intake pipe port 102 to suck the exhaust gas. It is designed to be returned to the system.

In this way, a part of the exhaust gas is returned to the intake system as an inactive component and added to the mixture to lower the combustion temperature to reduce the generation of ON component.

(Problems to be solved by the invention) However, in the above-described conventional technology, the operation of the rubber diaphragm 107 causes deterioration of the rubber diaphragm 107 due to heat, gasoline, exhaust gas (chlorine, bromine, etc.), There is a risk that airtightness or malfunction will occur and the recirculation of exhaust gas cannot be adjusted accurately.

Therefore, considering the heat resistance of the rubber diaphragm 107, a cooling device such as an EGR cooler is always required, which is disadvantageous in terms of space and cost.

Therefore, it is conceivable to use a bellows type actuator using a resin bellows having excellent heat resistance and gasoline resistance in the pressure sensitive portion instead of the rubber diaphragm 107.

As a fixing structure of such a resin bellows, for example, a solid flange 201 provided at one end of the bellows 200 is generally caulked and fixed as shown in FIG. However, the resin bellows 200 softens at a high temperature, and the fixed portion B of the bellows 200 tilts radially inward due to repeated operation due to negative pressure, and the upper plate 2
It interferes with 02. As a result, the operation hysteresis is increased, and further, the operation may be defective.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to use a resin bellows excellent in heat resistance to eliminate malfunction of the resin bellows at high temperature. It is to provide a bellows type actuator that can be used.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the hollow interior of an actuator body having a hollow interior is divided into two chambers by a resin bellows, and one end of the bellows is an actuator. A bellows type actuator, which is fixed to a main body and holds the other end in a free state and expands and contracts a bellows by a differential pressure between two chambers, is engaged with an inner circumference of a fixed end portion of the bellows, It is characterized in that an annular inner diameter support portion for regulating the inner diameter of the portion is provided.

(Function) Even if the bellows softens under high temperature conditions,
Since the inner circumference of the fixed end is supported by the inner diameter support portion and the inner diameter of the fixed end is regulated, the dimensional change of the inner diameter and the inward falling can be prevented.

(Example) Below, this invention is demonstrated based on the Example shown in figure. First
1 and 2 show an EGR valve to which a bellows type actuator according to an embodiment of the present invention is applied.

In the figure, reference numeral 1 denotes the entire EGR valve, which is composed of a schematic valve body 16 and an actuator A for opening and closing the valve body 16.

The actuator A is an actuator body 5 having a hollow inside.
The hollow interior of the two chambers is made into two chambers 61, 62 by a resin bellows 11.
It is configured to be divided into. That is, the actuator main body 5 is an inner hollow box-shaped configured by air-tightly joining the upper cup 2 to the opening edge of the bottomed cylindrical lower cup 4, and a negative pressure is externally applied to the central portion of the upper cup 2. It has a negative pressure introducing hole 3 introduced from.

On the other hand, a fixing flange 14 that projects outward in the radial direction is provided at one end of the resin bellows 11 that is housed inside the hollow of the actuator body 5, and this fixing flange 14
However, they are fixed by caulking at the joint edge portion 3a of the upper cup 2 and the lower cup 4.

The upper cup 2 is provided with an annular stepped portion 13 as an inner diameter support portion that engages the entire inner circumference of the fixed end portion of the bellows 11 and regulates the inner diameter of the fixed end portion.

In this example, the upper surface of the fixed flange 14 is in close contact with the inner surface of the upper cup 2, and the upper surface of the fixed flange 14 is provided with an annular groove 12 corresponding to the step portion 13. As a result, the inner diameter of the fixed end portion of the bellows 11 is regulated, and the bellows 11 is prevented from falling inward in the radial direction.

In addition, in this embodiment, the bellows 11 is formed into a cylindrical shape in consideration of its formability, and the opening on the free end side is airtightly closed by the lower plate 8.
That is, the flange 15 also extends to the open end of the bellows 11, and the flange 15 has an edge 8a of the lower plate 8.
Is fixed by crimping.

Further, the lower plate 8 is provided with a step portion 8b as an inner diameter support portion which engages with the inner circumference of the free end portion of the bellows 11 over the entire circumference thereof and regulates the inner diameter of the free end portion.

An upper plate 7 is superposed on the upper surface side of the lower plate 8, and one end of a valve body 10 inserted into the valve body 16 is connected and fixed to both plates 7 and 8. Upper plate 8
Functions as a spring retainer, and a spring 9 is interposed between the upper plate 8 and the upper cup 2 for urging the bellows 11 in a direction to extend the bellows 11.

A cylindrical guide portion 71 extending along the inner circumference of the bellows 11 is provided at the outer diameter end of the upper plate 7. The length of the guide portion 71 is set so that the distance between the tip of the guide portion 71 and the upper cup 2 is approximately the expansion / contraction stroke of the bellows 11.

On the other hand, the lower cup 4 is fixed to the valve body 16 by screws 18, 18. The valve body 16 is provided with an exhaust gas inlet 17 and an outlet 18a. The inflow port 17 and the outflow port 18a are partitioned by a valve seat 19, and the valve body 10 opens and closes a valve hole 20 provided in the valve seat 19.

As the resin material for the resin bellows 11, a material having excellent heat resistance, gasoline resistance, oil resistance, exhaust gas (including chlorine, bromine, etc.) resistance is selected according to usage conditions. In particular
A fluorine resin such as PTFE (tetrafluoroethylene resin) is suitable.

The EGR valve 1 configured as described above operates as follows.

First, when a negative pressure is introduced into the chamber 61 from the negative pressure inlet 3 and the pressure becomes relatively lower than that in the other chamber 62, the resin bellows
11 contracts against the spring force of the spring 9, and the lower plate 8 and the upper plate 7 rise. As a result, the valve body 10 also rises, and the valve body 10 in the valve body 16 separates from the valve seat 19 and opens the valve hole 20. As a result, exhaust gas is supplied from the inflow port 17 toward the outflow port 18a (see FIG. 1).

Next, when the degree of the negative pressure introduced from the negative pressure introduction hole 3 becomes low, the resin bellows 11 is extended by the urging force of the spring 9. Along with that, the lower plate 8 and the upper plate 7 descend, and the valve element 10 also moves downward to close the valve hole 20 provided in the valve seat 19. Therefore, the inlet 17 and the outlet
18a is cut off, and exhaust gas does not flow from the inflow port 17 to the outflow port 18a (see FIG. 2).

On the other hand, since the fixed end portion of the resin bellows 11 is fixed in the radial direction by the step portion 13 provided in the upper cup 2, the fixed end portion of the resin bellows 11 is firmly fixed at a high temperature. .

Further, although the resin bellows 11 has a large dimensional change due to heat, the inner and outer diameters thereof are regulated, so that the sealability of the chamber 61 at high temperature is improved.

In addition, since the inner diameter of the free end portion of the resin bellows 11 is also regulated by the step portion 8b of the lower plate 8, it is possible to prevent the free end portion from inclining at a high temperature.

3 and 4, another embodiment of the present invention is shown. In this embodiment, the same components as those in the above embodiment will be designated by the same reference numerals and will be described.
In this embodiment, the inner diameter support portion provided on the inner circumference of the fixed end portion of the bellows 11 is constituted by a metal support ring 23 which is separate from the upper cup 2.

Even with such a configuration, the support ring 23 can prevent the fixed end portion of the bellows 11 from falling inward, and the expansion and contraction operation of the bellows 11 can be smoothly performed.

Further, in this embodiment, the guide portion 71 of the upper plate 7 is
The length of is shortened. By thus shortening the length of the guide portion 71 as much as possible, the interference between the upper plate 7 and the bellows 11 due to the negative pressure operation is minimized.

The rest of the configuration and operation are the same as those of the above-mentioned embodiment, so the description thereof is omitted.

In the above embodiment, an example in which the bellows type actuator is applied to the EGR valve has been shown, but it is not limited to the EGR valve, heat resistance, gasoline resistance, etc. are required, and operability in a high temperature atmosphere is a problem. It can be widely used as a pressure regulator and an actuator for various control devices.

(Effects of the Invention) The present invention has the above-described configuration and operation, and since the inner circumference of the fixed end of the resin bellows is supported by the inner diameter support portion and the inner diameter of the fixed end is regulated, It is possible to prevent the resin from softening and falling inward. Therefore, when the bellows expands and contracts,
It is possible to prevent interference between the bellows and surrounding components, reduce hysteresis of operation, and improve durability of the bellows itself.

Further, since the inner diameter support portion forcibly regulates the dimensional change of the bellows diameter at high temperature, the airtightness inside the actuator body can be improved accordingly.

[Brief description of drawings]

1 and 2 are longitudinal sectional views of an EGR valve using a bellows type actuator according to an embodiment of the present invention in open and closed states, and FIGS. 3 and 4 are other embodiments of the present invention. FIG. 5 is a vertical cross-sectional view showing a valve-opened and valve-closed state of a bellows type actuator according to an example, and FIG. 5 shows a conventional diaphragm.
FIG. 6 is a schematic vertical cross-sectional view of the EGR valve, and FIG. 6 is a vertical cross-sectional view of essential parts showing an operating state when a bellows is used for the actuator. Explanation of code 1 …… EGR valve 2 …… Upper cup 3 …… Negative pressure introduction hole 3a …… Joint edge 4 …… Lower cup 5 …… Actuator body 61,62 …… Room, 7 …… Upper plate 8 ...... Lower plate, 9 ...... Spring 10 ...... Valve body, 11 ...... Resin bellows 12 ...... Concave groove 13 ...... Step section (inner diameter support section) 14 ...... Fixed flange J, 15 ...... Flange 16 ...... Valve Main unit, 18 …… screw 23 …… Support ring (inner diameter support part) A …… Actuator

Claims (1)

[Scope of utility model registration request] 1. A hollow interior of a hollow actuator body is divided into two chambers by a resin bellows, one end of the bellows is fixed to the actuator body, and the other end is held in a free state, so that the difference between the two chambers is reduced. In a bellows type actuator that expands and contracts a bellows by pressure, an annular inner diameter support portion that engages with an inner circumference of a fixed end portion of the bellows and restricts an inner diameter of the fixed end portion of the bellows is provided. Bellows type actuator.