JPH0648142Y2 - Vacuum limiter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a vacuum limiter.

[Prior art]

Conventionally, when the engine vacuum pressure rises extremely during deceleration during high-speed running of an automobile, there is a problem that engine oil consumption increases through the engine valve stem and CO, HC, etc. in exhaust gas increase. . In order to reduce such a problem, it is preferable to reduce the vacuum pressure in the intake manifold during deceleration. Therefore, conventionally, when the vacuum pressure becomes high during deceleration, a vacuum limiter is used to detect the vacuum pressure and supply the atmosphere into the intake manifold to control the vacuum pressure so that it is not too high. There is. Conventionally, when the differential pressure between the high pressure side atmosphere side fluid passage 30 and the low pressure side intake manifold side fluid passage 31 becomes equal to or more than a predetermined value as shown in FIG. The valve body 33, which closed the passage by the elastic force of the spring 32, is opened against the elastic force of the spring 32, and the air passes through the low pressure side fluid passage 31.
What is configured to flow to
It is disclosed as FIG. 1 in the publication. This device has a drawback that the pressure receiving area for sensing the pressure difference between the low-pressure side pressure and the high-pressure side pressure is small, and the operability varies greatly. In order to solve this drawback, as shown in FIG. 5, a blocking plate 35 having an opening 34 is interposed between the high pressure side fluid passage 30 and the low pressure side fluid passage 31, and a valve seat is provided on the low pressure side fluid passage 31 side. A diaphragm 37 having a portion 36 is provided, which is constantly urged in the closing direction by a spring 38, and a high pressure side fluid passage
When the pressure difference between the low pressure side fluid passage 31 and the high pressure side fluid passage 30 is small, it is in the state shown in the drawing, and the valve seat portion 36 is opened against the spring 38, and the atmosphere is supplied to the low pressure side fluid passage 31 through the opening 34 and the orifice 31a to increase the pressure receiving area for sensing the differential pressure. It is disclosed in FIGS. 3 and 4 in the 55-59870 publication.

[Problems to be solved by the device]

By the way, as described above, at the time of deceleration during high-speed running of the vehicle, it is necessary to open the vacuum limiter to replenish a large amount of air into the intake manifold. It is preferable not to replenish the mixture in order to prevent the air-fuel mixture from leaning and to maintain the idling stability and reproducibility.

However, when each of the conventional valves is used as a vacuum limiter, the pressure receiving surface of the valve body portion on which the high pressure atmosphere acts is different from the pressure receiving surface in the closed state of the valve body, and the differential pressure changes to open the valve body. The rate of change with the pressure receiving surface when activated is extremely small and can be considered to be constant at all times. Further, when the valve body is opened, the air in the high pressure side fluid passage easily flows into the low pressure side fluid passage, the pressure on the low pressure side rises, and the pressure difference decreases. Therefore, the opening degree of the valve body and the change in the air flow rate when opening the valve body from the closed state become insensitive, and when decelerating in the valve closed state, a large flow rate of air is not replenished early in the initial stage of deceleration. There is a problem that the reduction of CO, HC, etc. at the time of deceleration, which is the purpose of the term, is not satisfied.

Therefore, the present invention determines the pressure receiving area on which the high pressure side acts,
The problem is solved by making it small at the time of closing the valve and changing it largely at the initial stage of opening the valve so that the opening operation is made sensitive at the early stage of opening and the opening amount is increased, and the supply air amount is increased. At the same time, it is particularly intended to ensure that such a sensitive valve opening operation can be performed.

[Means for Solving the Problems]

In order to solve the above problems, the present invention provides a negative pressure chamber 14 in the case 8, one end of the negative pressure chamber 14 is connected to an atmosphere side passage 8a communicating with the atmosphere, and the other end is connected to an intake manifold. A seat surface 13 is formed in a communicating portion of the atmosphere side passage 8a with the negative pressure chamber 14, and a valve 18 is provided in the negative pressure chamber 14 on the side of the seat surface 13 side. A holding member 15 is provided, and the holding member 15 is provided so as to face the seat surface 13 so as to be able to move forward and backward, and is biased toward the seat surface 13; and the valve 18 has an inner protrusion that opens and closes the seat surface 13. Part 19
And a first pressure receiving surface 22 surrounded by the inner protrusion 19, and an inner protrusion
The second pressure receiving surface 23 formed on the outer peripheral portion of the 19 and the second pressure receiving surface 23
An outer peripheral protrusion 20 is formed so as to surround the outer periphery of the inner surface of the seat surface.
It is set so that a slight flow path gap 21 is formed with the inner surface 8b of the main body case in the state of being in contact with 13, and
A third pressure receiving surface 24 is formed on the outer circumference of 20, and a flow gap 17 is formed between the outer circumference of the holding member 15 and the inner surface of the case, and the flow cross-sectional area of the flow gap 17 is defined by the air passage 8a. The feature is that it is set to be almost equal to the distribution cross-sectional area.

[Action]

During idling of the engine in which the pressure difference between the pressure in the atmosphere side passage 8a and the pressure in the negative pressure chamber 14 is small, the valve is in the closed state as shown in FIG.

At this time, the atmospheric pressure is the first pressure formed inside the inner protrusion 19.
Only the pressure receiving surface 22 is operating. When the negative pressure in the negative pressure chamber 14 increases and the pressure difference with the pressure in the atmosphere side passage 8a increases during deceleration during high-speed traveling of the vehicle, the valve 18 opens against the spring 16. At the initial stage of opening the valve, the atmospheric pressure is applied from the gap between the inner protrusion 19 and the seat surface 13 to the inner protrusion 19.
It also acts on the second pressure receiving surface 23 formed between the outer protrusion 20 and the outer protruding portion 20, and the pressure receiving area changes significantly from S ₁ to S ₂ as shown in FIG.

Further, in the middle period of valve opening, the atmospheric pressure also acts on the third pressure receiving surface 24 formed between the outer protruding portion 20 and the outer periphery of the valve holding member 15, and the pressure receiving area further changes from S ₂ to S ₃ . It changes significantly.

Further, in the initial stage of valve opening, the pressure acting on the pressure receiving area S ₂ is suppressed from flowing into the negative pressure chamber 14 due to the presence of the outer protrusion 20, and the pressure acting on the pressure receiving area S ₃ in the middle period of valve opening. Is
The small gap 17 between the valve holding member 15 and the inner surface of the case suppresses the inflow into the negative pressure chamber 14.

Further, since the flow path gap 21 is provided, the negative pressure is not sealed between the inner and outer protrusions 19 and 20.

Furthermore, since the flow cross-sectional area of the flow gap 17 and the flow cross-sectional area of the atmosphere passage 8a are made substantially equal, a large amount of atmospheric pressure flows into the negative pressure chamber 14 through the flow gap 17 in the early and middle stages of valve opening. Suppressing, and when fully opened, the negative pressure chamber 14
The necessary distribution to

〔Example〕

Next, an embodiment of the present invention shown in FIGS. 1 to 3 will be described.

Reference numeral 1 is an air cleaner, 2 is an air flow meter, 3 is an intake pipe, 4 is a throttle valve, 5 is an intake manifold, and 6 is an engine. When the engine is started, air flows in from the air cleaner 1 and flows through the respective parts. Is sucked into the engine 6. 7 is a vacuum limiter, in which the main body case 8 and the negative pressure side case 9 are screwed together,
The threaded portion is caulked and connected. 10 indicates an O-ring. The outer end of the atmosphere side passage 8a in the main body case 8 communicates with the intake pipe 3 in the upstream portion of the throttle valve 4 by an air passage 11, and the outer end of the negative pressure side passage 9a in the negative pressure side case 9. Is communicated with the intake manifold 5 at the downstream portion of the throttle valve 4 by a negative pressure passage 12.
At the inner end of the atmosphere side passage 8a in the main body case 8, a seat surface 13 which is a tapered surface that widens inward is formed. In the negative pressure chamber 14 formed in the main body case 8,
A valve holding member 15 is slidably accommodated along the axial direction of the atmosphere side passage 8a, and a spring 16 is interposed between the valve holding member 15 and the inner surface of the negative pressure chamber case 9 so as to be constantly spring 16. This urges the valve holding member 15 toward the atmosphere-side passage 8a. A gap 17 is formed between the outer peripheral surface of the valve holding member 15 and the inner peripheral surface of the main body case 8. Reference numeral 18 denotes a valve, which is fixed to the surface of the valve holding member 15 on the atmosphere side passage 8a side. On the surface of the valve 18 on the side of the seat surface 13, an inner projection 19 and an outer projection 20 are integrally formed so as to integrally project on a circumference around the axis of the atmosphere-side passage 8a. A first pressure receiving surface 22 formed inside the inner projecting portion 19 and a second pressure receiving surface 23 formed between the inner projecting portion 19 and the outer projecting portion 20 are respectively formed. The inner protrusion
19 is formed in a pointed shape having a triangular cross section, and the diameter of the pointed portion 19a is set so that the pointed portion 19a fits and abuts the tapered seat surface 13. Also,
The outer protrusion 20 is also formed in a pointed shape, and the degree of protrusion is such that the tip of the outer protrusion 20 is the inner surface of the main body case 8 when the inner protrusion 19 is in contact with the seat surface 13 in a valve closed state. 8b has a slight flow path clearance 21 and is set so as to form a space 23a between the inner projection 19 and the outer circumference.

Further, the outer diameter of the outer protrusion 20 is formed to be smaller than the outer diameter of the valve holding member 15, and the third pressure receiving surface 24 is formed on the valve holding member 15 in the outer portion of the outer protrusion 20 and the outer side A space 24a is formed outside the protrusion 20. A gap 17 formed between the outer circumference of the valve holding member 15 and the inner circumference of the case 8 is formed by forming a plurality of axially extending projections 8c on the circumferential surface of the case 8 in the circumferential direction. A groove space 8d is formed between them so as to form an annular gap as shown in FIG. 3, and the annular area A ₂ and the flow area of the atmosphere passage 8a are formed.
Relation between A ₁ is set to A ₁ ≒ A _2.

The pressing load of the spring 16, the area of the first pressure receiving surface 22 surrounded by the inner protrusion 19 of the valve 18, and the area of the negative pressure receiving surface 15a which is the inner side surface of the valve holding member 15 are When the vacuum pressure (generally 500 to 550 mmHg) in the intake manifold 5 generated during idling acts in the negative pressure chamber 14, the negative pressure and the atmosphere side passage 8a
The pressing force of the spring 16 is greater than the pressure difference from the atmospheric pressure of, the closed state of the valve 18 is maintained, and at the time of deceleration during high-speed traveling of the vehicle, the high vacuum pressure (generally, in the intake manifold 5) 580 ~ 670 mmHg) acts in the negative pressure chamber 14, and when the differential pressure between the negative pressure and the atmospheric pressure on the atmosphere side passage 8a side is larger than the pressing force of the spring 16, the valve 18 opens. Is set.

When the engine is started, air flows through the air cleaner 1, the air flow meter 2, the intake pipe 3, the throttle valve 4, and the intake manifold 5 and is sucked into the engine 6. At this time, the atmospheric pressure in the intake pipe 3 acts on the atmosphere side passage 8a of the vacuum limiter 7 through the air passage 11, and the negative pressure generated in the intake manifold 5 passes through the negative pressure passage 12 inside the vacuum limiter 7. It acts in the negative pressure chamber 14 of. When the engine is idling, the vacuum pressure in the intake manifold 5 is low (500-550mmHg)
Therefore, the differential pressure between the pressure in the atmosphere side passage 8a and the pressure in the negative pressure chamber 14 is small. Therefore, the valve 18 is pushed in the closing direction by the pressing load of the spring 16, and the inner protrusion 19 of the valve 18 contacts the seat surface 13 to maintain the closing operation state. At this time, the outer protruding portion 20 has a minimum required clearance (minimum clearance established due to component tolerance) with the inner surface 8b.

The closing operation of the valve 18 prevents the air in the intake pipe 3 from bypassing into the intake manifold 5 through the vacuum limiter 7. Also,
If the vehicle decelerates while traveling at high speed, the vacuum pressure in the intake manifold 5 will be high (590 to 670 mm).
Hg), the differential pressure between the atmosphere side passage 8a and the negative pressure chamber 14 increases, and the negative pressure overcomes the pressing force of the spring 16 and moves the valve 18 against the spring 16 in the opening direction. Let At this time, the inner protrusion 19 of the valve 18 is
When separated slightly, the atmospheric pressure in the atmosphere-side passage 8a immediately acts on the second pressure receiving surface 23 of the valve 18 surrounded by the outer protrusion 20 from the gap. Therefore, at the same time that the valve 18 starts to open, the pressure receiving area of atmospheric pressure increases rapidly, the pressing force due to atmospheric pressure increases rapidly, and the differential pressure changes significantly.

Therefore, the amount of movement of the valve 18 in the opening direction rapidly increases from the state in which the valve 18 is slightly opened, and the air circulation area formed between the valve 18 and the inner surface of the main body case 8 increases rapidly.

Further, the atmospheric pressure also acts on the third pressure receiving surface 24 of the valve 18 surrounded by the valve holding member 15, and the pressure receiving area of the atmospheric pressure increases more and more, and the pressing force due to the atmospheric pressure increases more and more.
The air circulation area formed by 18 and the inner surface of the main body case 8 increases more and more.

Therefore, the flow rate of the air flowing from the intake pipe 3 into the intake manifold 5 through the vacuum limiter 7 increases, and the vacuum pressure in the intake manifold 5 is rapidly reduced.

In addition, the inner protrusion 19 of the valve 18 is formed in a pointed shape because the sealing property thereof is improved, and when the flat seal structure is adopted, the valve 18 resonates due to pulsation of negative pressure to generate a sound. This is to solve this problem.

Further, the outer protruding portion 20 is provided so that the atmospheric pressure acting on the first pressure receiving surface 22 as described above does not escape to the negative pressure chamber 14 as much as possible at the initial stage of valve opening. Also the flow path clearance
21 is formed because when the valve 18 is closed and the outer protrusion 20 is brought into close contact with the inner surface 8b of the case 8 and the gap 23a is completely sealed, the negative pressure inside the negative pressure chamber 14 after the valve 18 is closed. This is to prevent the above negative pressure from remaining in the space 23a when the pressure changes and the valve may not operate properly.

The reason why the relationship between the area A ₁ of the atmosphere-side passage 8a and the annular area A ₂ of the gap 17 is A ₁ ≈A ₂ is as follows. That is, the annular area A ₂ is as small as possible, and the atmospheric pressure acting on the second pressure receiving surface 23 in the early stage of valve opening and on the third pressure receiving surface 24 in the middle stage of valve opening escapes into the negative pressure chamber 14 as much as possible. However, if the annular area A ₂ is smaller than the area A ₁ of the atmosphere side passage 8a, the required flow rate cannot be secured when the valve 18 is fully opened. Therefore, by setting the relationship of A ₁ ≈A ₂ as described above, it is possible to improve the valve opening operability and solve the above problem.

[Effect of device]

As described above, according to the present invention, the pressure-receiving surface on which the pressure on the high-pressure side and the atmosphere-side acts is made small at the time of valve closing, increased rapidly at the initial stage of valve opening as compared with the time of valve closing, and further opened at the middle stage of valve opening. Since the valve opening amount can be increased more rapidly than in the initial stage, the valve opening operation can be made sensitive to increase the opening amount and the supply air amount. Therefore, when idling, the valve can be closed to shut off the supply of air, prevent the air-fuel mixture from leaning, and maintain idling stability and reproducibility. In addition, during deceleration, the valve opening amount is significantly changed in response to a slight negative pressure change at the beginning of opening of the valve element to increase the air supply amount, and CO, HC, etc. are reduced during deceleration. The purpose can be achieved satisfactorily.

Further, since the circulation gap 21 is provided between the outer protrusion 20 and the case inner surface 8b, the negative pressure during the previous operation is not sealed between the inner and outer protrusions 19 and 20, and the valve opening operation can be reliably performed. .

Furthermore, since the flow cross-sectional area of the flow gap 17 and the flow cross-sectional area of the atmosphere passage 8a are made substantially equal, in the early and middle stages of valve opening,
It is possible to prevent atmospheric pressure from escaping from the circulation gap 17 to the negative pressure chamber 14, and to secure a necessary flow rate from the atmosphere passage 8a to the negative pressure chamber 14 when fully opened.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention, FIG. 2 is a side sectional view of an essential part, FIG. 3 is a sectional view taken along the line BB of FIG. 1, and FIGS. It is each sectional drawing which shows two examples of a structure. 8 ... Case, 8a ... Atmosphere side passage, 9a ... Negative pressure side passage,
13 …… Seat surface, 14 …… Negative pressure chamber, 16 …… Spring, 17
…… Flow gap, 18 …… Valve, 19 …… Inner protrusion, 20 ……
Outer protrusion, 21 …… Flow gap, 22 …… First pressure receiving surface, 23 ……
2nd pressure receiving surface, 24 ... 3rd pressure receiving surface

Claims (1)

[Scope of utility model registration request] 1. A negative pressure chamber 14 is provided in the case 8, and the negative pressure chamber 14 is provided.
An air passage 8a communicating with the atmosphere at one end thereof, and a negative pressure passage 9a communicating with the intake manifold at the other end thereof, and the seat surface 13 is provided at the communicating portion of the atmosphere passage 8a with the negative pressure chamber 14. And a holding member 15 having a valve 18 on the seat surface 13 side is provided in the negative pressure chamber 14, and the holding member 15 is provided so as to be able to advance and retreat facing the seat surface 13.
It is biased in 13 directions, and the valve 18 is
Of the inner protrusion 19 that opens and closes 13, the first pressure receiving surface 22 surrounded by the inner protrusion 19, the second pressure receiving surface 23 formed on the outer peripheral portion of the inner protrusion 19, and the second pressure receiving surface 23. An outer peripheral projection 20 is formed so as to surround the outer periphery, and the projection amount of the outer projection 20 is slightly different from the inner surface 8b of the main body case with the inner projection 19 in contact with the seat surface 13. The flow path gap 21 is set to be formed, a third pressure receiving surface 24 is formed on the outer periphery of the outer protrusion 20, and a flow gap 17 is formed between the outer periphery of the holding member 15 and the inner surface of the case. And a flow cross-sectional area of the flow gap 17 is set to be substantially equal to the flow cross-sectional area of the atmosphere passage 8a.