JPH0435650Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid control valve that controls the flow rate of fluid, and more particularly to a control valve that uses a bellows to cancel pressure applied to a valve body. The fluid control valve of the present invention is effective when used as an air control valve for controlling the amount of auxiliary air supplied to an automobile engine.

It is generally known that in this type of control valve, a bellows is used for the purpose of canceling the pressure applied to the valve body (for example, see Utility Model Application No. 115073/1983). The shape of the resin bellows conventionally used has been the cut type shown in FIG. 1 or the radius cut type shown in FIG. 2. However, while the former type has a small spring constant and good controllability, it has the disadvantage that the effective diameter of the bellows changes greatly due to temperature changes or dust (fine dust) adhesion. Furthermore, the latter type has a high spring constant, and the spring characteristics of the bellows change greatly due to the influence of creep peculiar to the resin. Therefore, both bellows have the drawback of obstructing precise control of the valve body.

The inventors of the present invention noticed the above drawback for the first time and conducted various experiments and research to investigate the cause.

Next, the results of the analysis conducted by the present inventors will be explained. First, the bellows 2 shown in FIG. 1 has a temperature of -30
It varies from ℃ to +120℃. Therefore, bellows 2 becomes considerably soft at high temperatures. In such a state, if negative pressure from the outlet connected to the engine intake system is applied to the outer surface of the bellows 2, and atmospheric pressure is applied to the inner surface of the bellows, the bellows will be deformed as shown by the broken line in FIG. Due to this deformation, the apparent inner diameter a on the side surface of the bellows 2 is displaced outward from the inner diameter A indicated by the solid line, and as a result, the effective diameter (inner diameter+outer diameter/2) of the bellows 2 increases. Here, pressure cancellation by the bellows 2 is performed by balancing the pressure applied to the effective diameter of the bellows 2 and the pressure applied to the pressure receiving diameter of the valve 7, so that the effective diameter of the bellows 2 is initially If it becomes larger than the diameter of
It becomes impossible to completely cancel the pressure applied to the valve body.

As a result, the force in the direction (upward in the figure) that presses the one end surface 22 of the bellows 2 toward the valve body is larger than the force in the direction (downward in the figure) in which the spring valve body presses the one end surface 22 of the bellows 2 against the one end surface 22 of the bellows 2. As a result, the gap between the valve body and the seat of the housing becomes narrower and the amount of air supplied decreases, preventing the supply of an appropriate amount of air and causing engine malfunction.

Also, the soot that blows back from the engine intake diameter,
When dust, etc. passing through the air cleaner accumulates in the groove of the inner diameter A of the bellows 2, the effective diameter of the bellows 2 changes in the increasing direction and becomes larger than the pressure-receiving diameter of the valve body. will decrease.

On the other hand, with the radius cut type bellows 2 as shown in Fig. 2, it is thought that the above-mentioned change in effective pressure-receiving diameter does not occur, but since the spring constant is high, it is difficult to apply a certain force to the shaft, for example. Even if an attempt is made to continue to flow a predetermined amount of supplied air, if the creep of the resin progresses, the amount of supplied air will change by the amount that the load on the bellows changes. This obstructs the supply of an appropriate amount of air, resulting in engine malfunction.

This invention was devised in view of the analysis results independently found by the above inventors, and does not improve the spring characteristics, that is, maintains the same spring characteristics and creep characteristics as the notched bellows shown in Figure 1. in,
Changes in bellows characteristic diameter can be kept small,
As a result, the purpose is to enable precise control of the valve body over a long period of time.

In order to achieve the above object, the fluid control valve of the present invention has a plurality of flat ring parts on the side wall of the bellows for pressure cancelling, which are perpendicular to the moving direction of the bellows in a free state, and a connecting part that connects the ring parts. Among these connecting parts, at least the connecting part located on the high pressure side based on the pressure difference between the inside and outside of the bellows is formed into a cylindrical shape, so that adjacent ring parts are separated from each other to such an extent that they cannot come into contact with each other. A configuration is adopted in which the portion and the cylindrical connecting portion are substantially perpendicular to each other in the free state of the bellows.

Next, the operation of the fluid control valve of the present invention will be explained.
The pressure canceling bellows used in the control valve of this invention has a connecting part between the ring parts, so even if the ring part is deformed due to the pressure difference between the inside and outside when the bellows is hot, However, adjacent ring portions do not come into contact with each other. Similarly, even if dust adheres to the ring portions, the adjacent ring portions will not be connected by the dust.
Therefore, the effective diameter of the bellows does not change over time.

In addition, in the pressure canceling bellows used in the control valve of the present invention, the ring part and the connecting part are joined in a state where they are perpendicular to each other in the free state.
Alternatively, when the ring is displaced in the direction of contraction, stress due to the displacement will be concentrated at the joint between the ring portion and the connecting portion. This is synonymous with a decrease in the spring constant during expansion and contraction of the bellows as a whole. Therefore, the influence of the spring characteristics of the bellows on the operation of the fluid control valve is also reduced.

Therefore, in the fluid control valve of the present invention, the pressure canceling bellows can not only expand but also contract with a small spring constant, and can maintain a predetermined force on the valve body over a long period of time with almost no change in the effective diameter. This has the effect that it can be driven reliably.

Next, an explanation will be given based on an embodiment in which the control valve of the present invention is used as a solenoid valve for air control.

In Fig. 3, reference numeral 1 denotes a housing made of aluminum, and this housing 1 is formed with an inlet 11 for introducing auxiliary air from an air cleaner (not shown) and an outlet 12 for flowing the auxiliary air downstream of the throttle valve. . This housing 1 is then fixed to an automobile engine via the mounting hole 15 of the bracket 14. In addition, the flange portion 2 of the bellows 2
1 is sandwiched between a bellows plate 3 and an O-ring 4 and fixed to the housing 1 by a bush holder 5 while maintaining airtightness. Further, the tip end 22 of the bellows 2 is connected to the bellows holder 6 and the valve body 7.
In this state, the shaft 8 is engaged with the shaft 8. The valve body 7 is pressed against the holder 6 side by a spring 9, and thereby the bellows tip 22
And the valve body 7 is fixed.

Elastic bodies 71 and 72 are bonded to the inner surface of the valve body 7, and one elastic body 71 is attached to the valve body 7 and the bellows 2.
2, and the other elastic body 72 is provided to contact the seat portion 13 of the housing 1 when the valve body 7 is fully closed, and to seal against leakage of air flow. The shaft 8 is made of stainless steel, and a notch 81 is provided at its tip for guiding the fluid pressure on the inlet 11 side of the valve body 7 to the pressure chamber 23 inside the bellows 2 . The shaft 8 is slidably held by a Teflon bush 40 fixed to the bush holder 5.

Also, inside the housing 1 are a solenoid yoke 30, a magnetic plate 31, a coil 36,
and a bobbin 35 are housed therein, and they are connected to a mechanical plate 32 press-fitted into the housing 1.
The bushing holder 5 is pressed and fixed by the bushing holder 5. A fixed iron core 33 is press-fitted into the center of the magnetic plate 32, and a movable iron core 34 is press-fitted into the shaft 8 while facing the fixed iron core 33. The bobbin is provided to surround the fixed iron core 33, a coil 36 is wound around the bobbin 35, and this coil 36 is connected to the terminal 3.
It is connected to a lead wire 38 via 7.

Further, a bushing 39 is driven into the center of the fixed iron core 33, and this bushing 39 engages the bushing 4.
0 and supports the shaft 8. Shaft 8
A spring holder 41 is attached to the other end, and is pressed by a spring 42 via this holder 41. The two springs 9 and 42 disposed at both ends of the shaft 8 are held at their other ends by resist screws 43 and 44, respectively. The setting force of the spring 42 is larger than the setting force of the spring 9, and one of the agist screws 43 is used exclusively for adjusting the position of the valve body 7, and the other agist screw 44 is used exclusively for adjusting the position of the valve body 7.
is used to adjust the position of the stopper 45.

Next, the bellows 2 will be explained in detail.

The bellows 2 is made of tetrafluoroethylene resin, and its tip 22 has a cylindrical shape with a shaft through hole 24, and a flange 21 is formed on the opposite side. In addition, the peripheral wall of the bellows 2 has a plate thickness perpendicular to the bellows moving direction (X direction in Fig. 4) in a free state.
A large number of flat ring portions 25 of about 0.2 mm are formed. The outer end 25a of the ring part 25 is joined to the outer end 25a of the adjacent ring part 25, and the inner end 25b of the ring part 25 is joined to a thin cylindrical connecting part 26 having a plate thickness of about 0.2 mm. Note that the width h of the connecting portion 26 is approximately 0.4 mm.

This bellows 2 is manufactured through the following steps. First, a tip portion 22 as shown in FIG.
A closed cylindrical object having a flange portion 21 is cut from a tetrafluoroethylene resin rod. Thereafter, the side wall of the cylindrical object is scraped off from the outside to a width of 0.4 mm (indicated by the broken line A in Figure 5). Finally, the bellows 2 is formed by cutting the ring portion 25 from the inside of the cylindrical portion (indicated by the broken line B in FIG. 5).

Next, the operation of the control valve configured as described above will be explained.

In the above configuration, when a current is applied to the coil 36 via the lead wire 38, it is fixed from the fixed iron core 33 through the magnetic plate 32 and the yoke 10, and further from the magnetic plate 31 through the movable iron core 34. A magnetic field is generated that forms a loop back to the iron core 33. This magnetomotive field generates an attractive force between the movable iron core 34 and the fixed iron core 33. This suction force causes the movable iron core 34, the shaft 8, the bellows holder 6, and the one end surface 22 of the bellows 2 to
and the valve body 7 move to a position where they balance the forces of the springs 9 and 42, whereby the auxiliary air from the inlet 11 flows from the gap between the elastic body 72 of the valve body 7 and the seat portion 13 of the housing 1 to the outlet. It flows out to 12. When an even larger current is applied to the coil 36, the attractive force increases, the position in balance with the springs 9, 42 changes, and the opening area of the gap between the elastic body 72 of the valve body 7 and the seat portion 13 of the housing 1 also increases. Therefore, the amount of passing assist air also increases. For this purpose, the flow rate of the fluid also changes in proportion to the current.

By the way, the pressure at the inlet 11 is determined by the pressure guiding notch 8.
1 to the pressure chamber 23 inside the bellows 2, which acts in the direction of pressing one end surface 22 of the bellows 2 against the valve body 7, and the same pressure from the inlet 11 acts directly on the valve body 7, causing the valve body to close. Since it acts in the direction of pressing the body 7 against the one end surface 22 of the bellows 2, if the effective diameter of the bellows 2 and the pressure-receiving diameter of the valve body 7 are matched, the pressure at the inlet port 11 can be completely canceled. Similarly, the pressure applied to the outlet 12 side of the valve body 7 is completely canceled by the bellows 2. Therefore, the influence of the fluid on the opening/closing operation of the valve is canceled.

In particular, in the present invention, as is clear from the drawings, the ring portions 25 of the bellows 2 are formed so that all the ring portions 25 have a substantially uniform thickness. As a result, the pressure cancel function of the fluid can be achieved more reliably. That is, if the thickness of the ring portions 25 is not uniform, each ring portion 25 will
The amount of deformation between the bellows 2 is different, and as a result, the loads applied to both sides of the bellows 2 become unbalanced, making it impossible to cancel the pressure sufficiently. In contrast, in the bellows of the present invention, the ring portion 25 is formed to have a substantially uniform thickness as shown in the figure.
The influence of fluid pressure can be reliably canceled.

When this fluid control valve is used as a control valve for introducing atmospheric air into the intake system of an engine, the above-mentioned action causes the coil 36 to change depending on various engine conditions.
It is possible to control the amount of air supplied by controlling the current value applied to.

However, in this case, the outlet 12 is connected between the engine throttle valve and the combustion chamber, and the inlet 11 is connected between the engine throttle valve and the combustion chamber.
Since the bellows 2 is connected between the throttle valve and the air cleaner, the temperature of the bellows 2 may rise to about 120°C due to the engine intake air temperature, heat transfer from the engine, etc. However, in this example, even if the ring part 25 is deformed according to the pressure difference between the inside and outside of the ring part 25 (the state shown by the broken line in FIG. 4), the connecting part 26 connects the adjacent ring part 25.
This prevents the five concentric cores from coming into contact with each other.

In the above embodiment, a solenoid is used as the actuator for driving the shaft 8, but the same effect can be obtained by using another actuator (for example, a diaphragm type actuator).

In addition, for fluid control valves that are used in cases where the external pressure of the bellows 2 is higher than the internal pressure, or where dust is more likely to accumulate on the inside than on the outside, the inner groove should be made larger as shown in Figure 6. A similar effect can be obtained by using the bellows 2 which has a similar shape.

Further, the effect can be further enhanced by providing connecting portions 26 on both the inside and outside as shown in FIG.

[Brief explanation of the drawing]

1 and 2 are sectional views showing a part of the bellows of a conventional control valve, FIG. 3 is a sectional view showing an embodiment of the control valve of the present invention, and FIG. 4 is a sectional view of the bellows shown in FIG. 3. FIG. 5 is an explanatory diagram showing a manufacturing method of the bellows shown in FIG. 4, and FIGS. 6 and 7 are sectional views showing other examples of the bellows used in the control valve of the present invention. 2... Bellows, 7... Valve body, 8... Shaft, 25... Ring portion, 26... Connection portion.

Claims (1)

[Scope of utility model registration request] A valve body that opens and closes a fluid passage, a shaft coupled to the valve body, an actuator that drives the valve body via the shaft, and a valve body disposed on one side of the valve body so as to cover the shaft. a bellows forming a pressure chamber inside which introduces the pressure on the other side of the valve body, the bellows is made of a material with low rigidity, and a side wall of the bellows is provided with a direction in which the bellows moves in a free state. A plurality of plate-like ring parts that are substantially perpendicular to the bellows are formed, and a connecting part that connects the ring parts, and at least among these connecting parts, the connecting part located on the high pressure side based on the pressure difference between the inside and outside of the bellows has a cylindrical shape. to separate adjacent ring portions from each other to such an extent that they cannot come into contact with each other,
Furthermore, in the fluid control valve, the ring portion and the cylindrical connecting portion are substantially perpendicular to each other when the bellows is in a free state.