JPS6339498Y2 - - Google Patents

Description

[Detailed description of the invention] This invention supplies secondary air to the air control valve, especially the intake system or exhaust system of the engine, to control the air-fuel ratio of the air-fuel mixture to the engine or to control the air-fuel ratio in the exhaust gas from the engine. This invention relates to improvements in air control valves used to control the combustion of residual fuel in exhaust gas by controlling the amount of residual oxygen.

Conventionally, this type of air control valve includes an air intake port, an air discharge port, a valve seat provided between the air intake port and the air discharge port, and a valve that is connected to and separated from the valve seat and measures the circulating air. The valve body has a solenoid that controls the position of the valve body, and _the amount of electricity supplied to the solenoid is controlled by a command signal from a control unit based on a signal from a sensor that detects the state of engine exhaust gas, such as an O 2 sensor. However, some devices use this to control the amount of air flowing.

In the air control valve as described above, if the pressure applied to the air intake port and the air discharge port is large, for example, the pressure difference between atmospheric pressure and engine intake negative pressure is large, the valve body is subjected to force due to this pressure difference. It becomes extremely difficult to set the flow rate characteristics of the valve relative to the solenoid current value, and especially when used for engine air-fuel ratio control, there is a delay in the response of the valve body to the energization of the solenoid. There is a problem that the fuel ratio cannot be controlled.

In order to solve this problem, in the air control valve as described above, a bellows that forms a sealed space at the rear of the valve body, and a vent hole that communicates the sealed space in the bellows with the space on the front side of the valve body are provided. The load caused by the pressure difference between the back and front of the valve body is removed, and the opening between the valve body and the valve seat, that is, the amount of air flowing, is controlled by the solenoid current value and the return spring of the valve body. It is conceivable to make it possible to control the temperature accurately.

The bellows in the air control valve mentioned above is designed to minimize the influence on the flow rate characteristics determined by the solenoid and return spring by making the spring constant in the axial direction of the bellows as small as possible. It must not be deformed by the differential pressure between the suction port and the air discharge port, it must be able to withstand sudden pressure changes due to backfire, etc., it must be able to follow the rapid movement of the valve body, and it must have long-term durability and reliability, and it must be able to withstand high temperatures. The creep that occurs after a certain period of time under strain in an atmosphere of characteristics are required.

First, due to requirements such as heat resistance and oil resistance, it is conceivable to use a fluororesin such as Teflon (trademark) as the material for the bellows.

Regarding the shape of the bellows, for example, in order to prevent it from deforming due to the differential pressure between the air intake port and the air discharge port or the pressure of the backfire, it is sufficient to increase the wall thickness and decrease the number of folds. However, this method has the disadvantage that the spring constant of the bellows becomes large, which has an excessive effect on the flow rate characteristics of the valve.Also, the change in the spring constant of the bellows due to creep increases, which has a large effect on the flow characteristics. There is. Furthermore, if the number of folds in the bellows is small, the local bending stress becomes large, causing the bellows to break.On the other hand, if the number of folds in the bellows is increased, the shape of the bellows is maintained in the axial center of the bellows. There are disadvantages in that it is difficult to do so, and deformation is likely to occur due to large pressures such as those caused by backfires.

This invention was made to solve the above-mentioned problems, and it has a small spring constant, so it does not deform due to the pressure difference between the air intake port and the air discharge port, or large pressure such as a backfire. It has a bellows that can follow the fast movement of the valve body, has long-term durability and reliability, has minimal creep, is less likely to get caught in foreign objects such as carbon, and has excellent oil and heat resistance. The purpose is to provide air control valves.

This invention consists of an air suction port, an air discharge port, a valve seat provided between the air suction port and the air discharge port, a valve body that comes into contact with and separates from this valve seat to measure the circulating air, and An air control valve having a solenoid that controls the position of the valve body includes a bellows that forms a sealed space at the rear of the valve body, and a passage formed in the valve body that communicates the sealed space with a space on the front side of the valve body. The bellows is made of fluororesin, and has an effective diameter of 20 mm or less, a free mounting length of 20 mm or less, and an effective stroke of 5 mm or less, and the number of folds is 5 to 15.
The above object is achieved by setting the thickness of the pleats to 0.1 to 0.25 mm.

Embodiments of the present invention will be described below with reference to the drawings.

This embodiment includes an air suction port 1, an air discharge port 2, a valve seat 3 provided at a position between these air suction port 1 and air discharge port 2, and a valve seat 3 that is in contact with and separate from this valve seat 3 and that allows air to flow through the valve seat 3. In an air control valve V having a valve body 4 for metering and a solenoid 5 for controlling the position of the valve body 4, the air control valve V is attached to the opposite side of the valve body 4 to the valve seat 3, The bellows 7 is provided with a bellows 7 forming a sealed space at the back, and a vent hole 9 formed in the valve body 4 and communicating the sealed space 6 with the space 8 on the front side of the valve body.
is made of fluorine resin, and its effective diameter is
20mm or less, the free installation length is 20mm or less, the effective stroke is 5mm or less, the number of pleats is 5 to 15, and the thickness of the pleats is 0.1 to 0.25mm.

The valve seat 3 is press-fitted into the housing 10, and a valve lip 11 made of an elastic material such as rubber is baked into the inner corner of the valve seat 3 facing the valve body 4 (see Fig. 2). reference).

The valve body 4 is integrally formed of the same material as the bellows 7, and is connected to the flange 12A by a bellows holder 13 that is press-fitted into the tip of a shaft 12 that passes through the center of the bellows 7 in the axial direction. is fixed between.

The shaft 12 extends into the stator core 15 through the rear end opening 14 of the bellows 7, and contacts the outer periphery of a moving core 16 press-fitted into the shaft 12 at a position adjacent to the rear side of the bellows rear end opening 14. The stator core 15 is supported by a bearing bush 17 and a bearing bush 18 disposed inside near the rear end of the stator core 15 so as to be movable in the axial direction within a certain range.

A rear end portion of the stator core 15 is provided with a yoke 20 that encloses and supports the bobbin 19 of the solenoid 5.
It is provided with a screw hole 22 that protrudes rearward from the rear end, is coaxial with the shaft hole 21 in which the shaft 12 is disposed, and opens at the rear end. An adjusting screw 2 is inserted into this screw hole 22 from the rear end.
3 are screwed together, and the tip projection 24 of the adjusting screw 23 and the shaft 12
The set length of a return spring 26 interposed between the rear end projection 25 and the return spring 26 is adjusted, thereby adjusting the urging force in the direction in which the tip of the shaft 12 protrudes. A sealing material is applied to the outer periphery of the adjusting screw 23 to prevent it from loosening and to maintain airtightness.

A bearing bush 17 that contacts the outer periphery of the moving core 16 is supported on the inner periphery of a magnetic plate 27. This magnetic plate 27 is attached to the yoke 20 at the flange 27B on the end surface of the housing 10 on the solenoid 5 side.
It is tightened and fixed together with the flange 20A by bolts 28. Reference numeral 27A indicates a communication hole formed in the magnetic plate 27 and communicating the front and rear spaces thereof.

In other words, the yoke 20 includes the bobbin 1
9 and the magnetic plate 27 with the bolt 28.
It is tightened and fixed in the direction of pressing against the end surface of the housing 10. Reference numeral 29 in the figure indicates an O-ring disposed between the rear end of the bobbin 19 and the yoke 20, and 30 indicates an O-ring disposed at the contact portion between the outer periphery of the tip of the bobbin 19, the inner circumferential surface of the yoke 20, and the magnetic plate 27. , 31 is yoke 2
0 flange 20A and magnetic plate 27
O-rings are shown arranged on the contact surfaces of the stator core 15, thereby preventing water from leaking into the stator core 15 portion.

The front end 27C of the magnetic plate 27 protrudes into the bellows arrangement space 32 in the housing 10, and the bellows 7 is inserted between the magnetic plate 27 and a stepped portion 32A formed in the bellows arrangement space 32 via a packing 33. The thick rear end portion 7A is sandwiched therebetween. Therefore, the bellows 7 isolates the sealed space 6 inside the bellows 7 from the bellows arrangement space 32 (air discharge port 2).

Reference numeral 34 in the figure indicates a ring-shaped rubber cover attached to the outer periphery of the rear end of the yoke 20, and the space between the inner periphery of the rubber cover 34, the rear end of the stator core 15, and the outer periphery of the rear end of the yoke 20 is filled. The terminal 36 and a portion of the lead wire 37 are molded in an insulating state by a filler 35 such as a thermosetting epoxy resin.

The O-rings 29 and 30 have a waterproof function, and when filling with the filler 35, the filler in a fluid state passes through the filler injection port 20B before hardening and flows into the yoke 2.
It has a function of preventing the liquid from entering the stator core 15 and flowing out to the stator core 15 side. Further, in the figure, reference numeral 38 indicates a varnish tube, 39 an air control valve mounting bracket, 40 a bolt, and 41 a spring washer.

As shown in FIG. 2, the shape of the bellows 7 is such that the number of folds 7B is nine, and
The thickness t of the pleats 7B is 0.1 to 0.25 mm. As shown in Fig. 3, the number of folds 7B in the bellows is determined by the experimentally determined relationship between the number n of folds in the bellows and the amount of creep, and the amount of creep is small and the deformation pressure resistance of the bellows is suitable for practical use. It is determined from the range that is the target. Also, the thickness t
As shown in FIG. 4, this is based on the relationship between the thickness t of the pleat 7B portion and the amount of creep, and the results obtained based on the range in which the amount of creep is small and the durability and pressure resistance are practical.

Here, other conditions for the bellows 7 are that the free length is 20 mm or less, especially 10 to 20 mm, due to installation constraints, and the effective diameter of the bellows 7, that is, the portion of the valve seat 3 that contacts the tip of the valve lip 11. The diameter D is the differential pressure ΔP between the air intake and air discharge ports = 300 mmHg or less, the maximum air flow rate 1000/min
The condition is that D≦20mm, and the effective stroke is 5
mm or less.

In the above air control valve, when a current is applied to the solenoid 5 via the lead wire 37, the magnetic field generated by this is applied to the stator core 15, yoke 20, magnetic plate 2
7 and the moving core 16 to form a loop to the stator core 15, and suction force is generated between the stator core 15 and the moving core 16.

Therefore, the shaft 12 and bellows 7 together with the moving core 16 are connected to the return spring 26.
It resists and is attracted depending on the strength of the magnetic field. Therefore, the valve body 4, which is the tip of the bellows 7, and the valve lip 11 of the valve seat 3 are separated, allowing air to flow from the air intake port 1 to the air discharge port 2.
In this case, the sealed space 6 in the bellows 7 is communicated with the space 8 on the front side of the valve body 4 through the vent hole 9 formed in the valve body 4, so the pressure between the two is the same, and therefore the suction No load is applied to the valve body 4 in the axial direction due to the pressure difference between the side and the discharge side, and the opening degree of the valve body 4 and the valve seat 3, that is, the amount of air flowing through it, is determined by the current value to the solenoid 5 and the compression coil spring. It will be determined only by the relationship with 26. The air flow rate can thus be made proportional to the current to the solenoid 5.

In addition, the bellows 7 for pressure compensation does not deform due to the pressure difference between the suction side and the discharge side or large pressure changes due to backfire, etc., has a small spring constant, and has a minimum amount of creep. It can follow the fast movement of the valve body 4,
In addition, it has long-term durability and reliability, does not break due to repeated operation, does not allow foreign substances such as carbon to adhere between the folds, and has excellent heat resistance and oil resistance, so the amount of air flowing Solenoid 5
can be made exactly proportional to the current applied to the

Since the present invention is configured as described above, it has an excellent effect in that the amount of air flowing through the air can be made proportional to the current value applied to the solenoid.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the air control valve according to the present invention, Fig. 2 is an enlarged sectional view showing the bellows and valve seat in the same embodiment, and Figs. 3 and 4 show creep of the bellows. FIG. 3 is a diagram showing the relationship between the amount and the number of folds of the bellows, and the relationship between the bellows thickness. V... Air control valve, 1... Air intake port, 2... Air discharge port, 3... Valve seat, 4... Valve body, 5... Solenoid, 6...
Closed space, 7...Bellows, 7A...Folds, 8...
...Space on the front side of the valve body, 9...Vent hole, 26...Return spring.

Claims (1)

[Scope of utility model registration request] An air intake port, an air discharge port, a valve seat provided between the air intake port and the air discharge port, a valve body that is in contact with and separate from the valve seat and measures the circulating air, and In an air control valve having a solenoid for position control, a bellows forming a sealed space at the rear of the valve body, and a bellows formed on the valve body,
A ventilation hole communicating the sealed space with the space on the front side of the valve body is provided, and the bellows is made of fluororesin, and has an effective diameter of 20 mm or less, a free installation length of 20 mm or less, and an effective stroke of 5 mm or less. year,
And, the number of folds is 5 to 15, and the thickness of the folds is
An air control valve characterized by a diameter of 0.1 to 0.25mm.