JPS58126625A - Negative pressure switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects negative pressure above a certain level.1. The present invention relates to a negative pressure switch that opens and closes the switch when the negative pressure pulsates, and particularly relates to a negative pressure switch suitable for controlling an internal combustion engine or the like in which the negative pressure has large pulsations.

For example, in internal combustion engines for automobiles, various exhaust gas purification devices are controlled according to the negative pressure in the intake pipe in order to reduce harmful components in the exhaust gas. Conventionally, there has been a negative pressure switch used in such a control device as shown in FIG. That is, the negative pressure switch has a switch part A', a valve part B', and an atmospheric pressure correction mechanism C.
′ is provided. The switch part A' is a switch 1',
The switch 1' is comprised of a switch actuator 2' that opens and closes the switch 1', and the actuator 2' is attached to a diaphragm 4' whose periphery is fixed to a casing 3'. The valve part B' consists of a valve body 5' and a valve seat 6'.
The chamber above ' is divided by a diaphragm 4' into a switch chamber θ' and an output negative pressure chamber P', and the output negative pressure chamber P' is communicated with the atmosphere via an orifice 7'. . A compression spring 8' is provided between the valve seat 6' and the switch actuator 2', and the actuator 2' is always connected to the switch 1.
It is designed to press in the direction of .

The chamber below the valve sB' is divided around the periphery into an input negative pressure chamber Q' and an atmospheric pressure chamber R' by a diaphragm 9' fixed to the casing 3'. 10
It is connected to the intake pipe of the internal combustion engine through '. A bellows 11' whose interior is maintained at a constant negative pressure is provided within the atmospheric pressure chamber R'. This bellows 11
Atmospheric pressure is introduced around the bellows 1 through the communication hole 13' of the cover 12', and due to changes in atmospheric pressure, the bellows 1
1' is designed to expand and contract. That is, this bellows 11' constitutes an atmospheric pressure correction mechanism C'. The valve body 5' is connected to the diaphragm 9' and the upper surface of the bellows 11', and is normally seated on the valve seat 6' by the tension of the bellows 11'. An adjusting screw 14' is attached to the lower surface of the bellows 11', and an adjusting nut 15'
The cover 12' is supported by the cover 12'.

To explain the operation of such a negative pressure switch, normally the valve body 5' is seated on the valve seat 6', and the space between the output negative pressure chamber P' and the input negative pressure chamber Q' is closed. The output negative pressure chamber P' is maintained at atmospheric pressure through the orifice 7', and the switch actuator 2' is pressed against the switch 1' by the compression spring 8'.
For example, switch 1' is open.

When the internal combustion engine is driven and the intake pipe becomes negative pressure,
The negative pressure is transmitted to the input negative pressure chamber Q' through port 10'. When the negative pressure is below a certain value, the downward pulling force of the bellows 11' is greater than the upward suction force of the diaphragm 9', and the switch 1' is maintained in the same state. However, when the negative pressure in the intake pipe becomes extremely large, such as during engine braking, the negative pressure in the input negative pressure chamber Q' also increases, and the diaphragm 9' is sucked upward, causing the valve body 5' to It moves upward against the tensile force of the bellows 11'. Therefore, the input negative pressure chamber q' and the output negative pressure chamber P' communicate with each other, and the inside of the output negative pressure chamber R', which is provided with the orifice 7' between it and the atmosphere, becomes a negative pressure. The diaphragm 4' is thereby drawn downwards and the switch actuator 2' moves away from the switch 1' against the compression spring 8', so that the switch 1' is closed.

When the negative pressure in the intake pipe decreases, the negative pressure in the input negative pressure chamber Q' also decreases, and the valve element 5' is seated on the valve seat 6' due to the tensile force of the bellows 11'. As a result, the output negative pressure chamber P' is isolated from the input negative pressure chamber Q', and the orifice T' is passed through the 1.
The pressure increases due to the atmospheric air introduced. Therefore, the switch actuator 2' is pressed by the spring 8' into contact with the switch 1'. In this way switch 1'
The opening and closing operations are performed.

This type of negative pressure switch has good response (and stable control performance), so it is often used in internal combustion engine control devices. However, such a negative pressure switch is It also responds very well to internal combustion engines, so it can be used in applications where there is a lot of negative pressure pulsation, such as internal combustion engines for automobiles.

In this case, the valve body moves violently, causing problems such as vibration noise caused by collision between the valve body and the valve seat, and a decrease in durability. In order to solve this problem, it would be possible to change the pressure-receiving area of the diaphragm and the operating characteristics of the bellows, but this would change the characteristics of the atmospheric pressure correction mechanism, so the predetermined atmospheric pressure correction coefficient It becomes difficult to have It is also possible to reduce the movement stroke of the valve body, but in reality, the value is 03 to 0.
If it has to be a very small value of about 5u, it will be difficult to process the
Very difficult.

In view of the above-mentioned problems, the present invention aims to reduce the generation of vibration noise without affecting the atmospheric pressure correction mechanism.
However, it is an object of the present invention to obtain a negative pressure switch without deteriorating its durability. A further object of the present invention is to obtain a negative pressure switch that can substantially reduce the movement stroke of a valve body through simple processing.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
FIG. 2 shows the first embodiment, in which, like the conventional one, the input negative pressure chamber Q is communicated through port 10 with a negative pressure detection part such as an intake pipe (not shown) of the internal combustion engine. It looks like this. A communication passage 16 is provided between the input negative pressure chamber Q and the output negative pressure chamber P, and this communication passage 16 is opened when the valve body 5 separates from the valve seat 6, and the valve body 5 It can be closed by sitting on the seat 6.

The output negative pressure chamber P also communicates with the atmosphere via an orifice 7.

The valve body 5 is connected to a diaphragm 9 that defines an input negative pressure chamber Q and an upper surface of a bellows 11.

The interior of the bellows 11 is maintained at a predetermined negative pressure, and the atmosphere is introduced around it through the communication hole 13 of the cover 12, so the valve body 5 normally closes the communication path 16.
The biasing force in the closing direction changes depending on the atmospheric pressure. That is, the bellows 11 constitutes an atmospheric pressure correction mechanism C.

Further, the bellows 11 is fixed to the cover 12 by tightening an adjusting screw 14 attached to the lower surface with an adjusting nut 15, and the initial contact force of the valve body 5 against the valve seat 6 is adjusted. It has become.

The upper surface of the output negative pressure chamber P is partitioned by a diaphragm 4 whose periphery is fixed to the casing 3, and the switch actuator 2 is attached to the center of the diaphragm 4. The actuator 2 opens or closes the switch 1 by contacting and separating from the switch 1 attached to the upper part of the casing 3.

The above configuration is exactly the same as the conventional one shown in FIG. 1, but in the present invention, the arrangement of the elastic body such as a spring that presses the actuator 2 toward the switch 1 is devised. In the embodiment shown in FIG. 2, a compression spring 17, which is a compression elastic body, is provided between the actuator 2 and the valve body 5. This spring 17
This pushes the actuator 2 toward the side where it comes into contact with the switch 1, and also pushes the valve body 5 to suppress its movement.

With the above configuration, until the negative pressure in the input negative pressure chamber Q reaches a constant value, the valve body 5 is not displaced and the switch 1 is maintained as it is, as in the conventional case. When the negative pressure in the input negative pressure chamber Q exceeds a certain value, the valve body 5 rises, the communication passage 16 opens, and the pressure in the output negative pressure chamber P also becomes negative. the result,
The diaphragm 4 is sucked downward, and the actuator 2 descends. At this time, the spring 17 is greatly compressed by both the upward displacement of the valve body 5 and the downward displacement of the actuator 2. That is, a large force is generated that opposes the upward displacement of the valve body 5. The larger the negative pressure in the input negative pressure chamber Q, the greater the upward force applied to the valve body 5 by the diaphragm 9. At that time, the negative pressure in the output negative pressure chamber P also increases, causing the diaphragm 4 to , the downward force applied to the valve body 5 via the spring 17 is large (as a result, the upward displacement of the valve body 5 is suppressed to about the required minimum opening area of the valve portion B. , the thickness of the deterrent force increases exponentially with the amount of displacement of the valve body 5, that is, it hardly affects the atmospheric pressure correction mechanism C (and does not require particularly precise machining). Without this, the movement stroke of the valve body 5 can be kept small.If the movement stroke of the valve body 5 is small, even if the valve body 5 vibrates due to negative pressure pulsation, its amplitude is small, so that the movement stroke of the valve body 5 can be kept small. The vibration noise caused by the impact with the valve seat 6 is reduced, and a decrease in durability due to this can be prevented.

FIG. 3 shows another embodiment, in which not only a compression spring 18, which is a compression elastic body, is provided between the valve body 5 and the actuator 2, as in the case of FIG. , a compression spring 1 between the valve seat 6 and the actuator 2 similar to the conventional one shown in FIG.
A compression elastic body such as No. 9 is also provided. In this example as well, the same effects as in the embodiment shown in FIG. The spring 18 may have only the role of suppressing the movement stroke when the valve body 5 is displaced. That is, the set load of the spring 18 can be made almost zero,
The function of the atmospheric pressure correction mechanism C can be prevented from being affected.

As described above, according to the present invention, an elastic body such as a spring that presses the valve body in the closing direction is provided between the actuator that opens and closes the switch and the valve body that opens and closes between the input and output negative pressure chambers. Because of this, when the valve body is displaced in the opening direction and the actuator operates,
The elastic body is compressed from both sides, and displacement of the valve body is suppressed with a large force. Therefore, the movement stroke of the valve body can be kept small, reducing vibration noise and improving durability. Moreover, it has almost no effect on the atmospheric pressure correction function and requires almost no precise processing technology. Therefore, it is possible to obtain a negative pressure switch that is suitable for applications where negative pressure pulsates rapidly, such as internal combustion engines of automobiles.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view showing a conventional negative pressure switch, FIG. 2 is a vertical cross-sectional view showing an embodiment of the negative pressure switch of the present invention, and FIG.
The figure is a vertical cross-sectional view of a main part showing another embodiment of the present invention. 1...Switch, 2...Switch actuator, 4...
Diaphragm, 5...valve body, 6...valve seat, T...
Orifice, 9...Diaphragm, 11...Bellows, 16...Communication path, 17, 18.19...Compression spring, C...Atmospheric pressure correction mechanism, P...Output negative pressure chamber, Q
...Input negative pressure chamber.

Claims (1)

[Claims] An input negative pressure chamber (Q) into which the negative pressure of the detection section is introduced; an output negative pressure chamber CP) communicated with this input negative pressure chamber (Q) via a communication passage (16); and an input negative pressure chamber. a valve body (5) that is operated by the negative pressure in (Q) and opens and closes a communication passage (16) between the input negative pressure chamber (Q) and the output negative pressure chamber (P);
16); an atmospheric pressure correction mechanism (C) that constantly biases the valve body (5) in the closing direction and changes the biasing force according to changes in atmospheric pressure; negative pressure in the output negative pressure chamber (Q); and by leaving the switch (1), the switch (1) is activated.
); an actuator (2) that opens or closes the actuator (2);
) and the valve body (5), and presses the actuator (2) toward the side where it contacts the switch (1), and moves the valve body (5) in the direction of closing the communication passage (16). A negative pressure switch consisting of an elastic body such as a pressing spring (17);