JPH0833114B2 - Bakiyu limiter - Google Patents

Description

Detailed Description of the Invention a. OBJECT OF THE INVENTION A-1. Field of Industrial Application The present invention relates to a vacuum limiter.

2. Prior art Conventionally, during deceleration during high-speed running of an automobile,
When the engine vacuum pressure rises extremely, there is a problem that the consumption of engine oil increases via an engine valve stem (not shown) and CO, HC, etc. in the exhaust gas increase. In order to reduce such a problem, it is preferable to reduce the vacuum pressure in the intake manifold during the 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, for example, the sixth type is used as such a vacuum limiter.
As shown in the figure, when the pressure difference between the high pressure side fluid passageway (30) and the low pressure side fluid passageway (31) exceeds a predetermined value, the valve body (33) that closed the passageway by the elastic force of the spring (32). ) Is opened against the elastic force of the spring (32) so that air flows to the low pressure side fluid passage (31), as shown in FIG. 1 of Japanese Utility Model Publication No. 55-59870. It is disclosed. This device has the drawbacks that the pressure receiving area for sensing the pressure difference between the low pressure side and the high pressure side is small, and the operating characteristics vary widely. To solve this drawback,
As shown in FIG. 7, a blocking plate (35) having an opening (34) is interposed between the high pressure side fluid passageway (30) and the low pressure side fluid passageway (31), and a valve is provided on the low pressure side fluid passageway (31) side. A diaphragm (37) having a seat portion (36) is provided, and this is always provided with a spring (3
8) is urged in the closing direction by the high pressure side fluid passage (30)
And the high pressure side pressure sensing chamber (39) are connected by a communication path (40),
When the differential pressure between the low-pressure side fluid passage (30) and the high-pressure side fluid passage (31) is small, it is in the state shown in the figure, and when the differential pressure becomes large, the valve seat (36) opens against the spring (38). It operates and supplies the atmosphere to the low pressure side fluid passage (31) through the opening (34) and the orifice (37) to increase the pressure receiving area for sensing the differential pressure. It is disclosed in FIGS. 3 and 4 in the publication.

A-3. Problems to be Solved by the Invention By the way, as described above, at the time of deceleration during high-speed running of the automobile, it is necessary to open the vacuum limiter to replenish a large amount of air into the intake manifold. When the engine is idling, it is preferable to close the vacuum limiter and not supply air to prevent leaning of the air-fuel mixture, and to maintain stability and reproducibility of idling.

However, when each of the conventional valves is used as a vacuum limiter, the pressure receiving surface of the valve body where high pressure acts is different from the pressure receiving surface in the closed state of the valve body and the valve body opens to operate. The rate of change with the pressure receiving surface 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 becomes insensitive when the valve body starts to open from the closed state, and the air flow rate change becomes insensitive when the valve body starts to open. Therefore, when decelerating in the above-mentioned valve closed state, a large flow rate of air is not replenished early in the initial stage of deceleration, and
There is a problem that the reduction of CO, HC, etc. is not satisfied. Further, as described above, in the case where the diaphragm is used, there are problems of durability of the diaphragm and a problem that the mounting structure is complicated and the cost is high.

Therefore, the present invention, the pressure receiving surface on which the pressure on the high pressure side acts,
The problem is solved by making the valve smaller when the valve is closed and making a large change in the initial valve opening, increasing the opening amount by increasing the opening amount by making the valve opening differential more sensitive in the initial valve opening. The purpose is to do.

B. Structure of the invention b-1. Means for solving the problem In order to solve the above-mentioned problems, the present invention provides a negative pressure chamber in the body, and one end of the negative pressure chamber communicates with the atmosphere. And a negative pressure side passage communicating with the intake manifold at the other end, and in the negative pressure chamber, a valve can be opened and closed facing the seat surface formed in the atmosphere side passage and always in the closing direction. The valve is biased by a spring, and the valve has an inner protrusion located on a surface facing the seat surface formed in the atmosphere-side passage and opening and closing the seat surface, and a gap between the inner projection and the outer periphery of the inner projection. And a negative pressure chamber communicated with the space formed by the inner protrusion and the outer protrusion in a small flow area in a valve closed state in which the inner protrusion contacts the seat surface. It is characterized in that a communication means for allowing the communication is provided.

-2. Action The valve is closed as shown in Fig. 1 when the engine is idling, where the differential pressure between the pressure in the atmosphere side passageway (8a) and the negative pressure in the negative pressure chamber (14) is small.

At this time, the atmospheric pressure acts only on the surface (22) formed inward of the inner protrusion (19). When the negative pressure in the negative pressure chamber (14) increases and the differential pressure with the pressure in the atmosphere side passageway (8a) increases during deceleration during high-speed running of the vehicle,
The valve (18) is opened against the spring (16).
By this opening operation, the atmospheric pressure also acts on the surface (23) formed between the inner projection (19) and the outer projection (20) than the gap between the inner projection (19) and the seat surface (13). However, the pressure receiving area changes significantly. In addition, the pressure acting on the pressure receiving area that has significantly changed in the initial stage of valve opening is suppressed from flowing into the negative pressure chamber (14) due to the presence of the outer protrusion (20). Further, by having the communication means such as the gap (21), the negative pressure is sealed in the space (23a) formed by the inner protrusion (19) and the outer protrusion (20) when the valve is closed. There is no.

B-3. Embodiment Next, a first embodiment of the present invention shown in FIGS. 1 and 2 will be described.

(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. It flows in from the air cleaner (1), flows through the respective parts, and is sucked into the engine (6). Reference numeral (7) is a vacuum limiter, in which the main body case (8) and the negative pressure side case (9) are screwed together, and the screwed portion is caulked and connected. (1
0) 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 negative pressure side. The outer end of the negative pressure side passage (9a) in the case (9) communicates with the intake manifold (5) downstream of the throttle valve (4) by the 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 expands inward is formed. In the negative pressure chamber (14) formed in the main body case (8), the valve holding member (15) is slidably accommodated along the axial direction of the atmosphere side passageway (8a). A spring (16) is compressed between the inner surface of the negative pressure side case (9) and the inner surface of the negative pressure side case (9), and the valve holding member (15) is constantly connected to the atmosphere side passageway (8a) by the spring (16).
Urged to the side. A gap (17) is formed between the outer peripheral surface of the valve holding member (15) and the inner peripheral surface of the 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 passageway (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 provided on a circumference centered on the axis of the atmosphere-side passage (8a). ) Are formed integrally with each other, and are formed between the first pressure receiving surface (22) formed inside the inner protrusion (19), the inner protrusion (19), and the outer protrusion (20). Two pressure receiving surfaces (23) are formed respectively.
The inner protrusion (19) is formed in a pointed shape having a triangular cross section, and the pointed portion (19a) is fitted into and abuts the tape-shaped sheet surface (13). The diameter of (19a) is set. Further, the outer protrusion (20) is also formed in a pointed shape, and in the valve closed state in which the inner protrusion (19) is in contact with the seat surface (13), the outer protrusion (20) is It is set so that a slight gap (21) is formed between the tip end of 20) and the inner surface (8b) of the body case (8). It should be noted that 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 negative side surface of the valve holding member (15). When the vacuum pressure (generally about 500 to 550 mmHg) in the intake manifold (5) generated when the engine is idling acts in the negative pressure chamber (14), the area of the pressure receiving surface (15a) is The pressing force of the spring (16) is greater than the pressure difference between the negative pressure and the atmospheric pressure on the atmosphere side passageway (8a) side, and the closed state of the valve (18) is maintained. , High vacuum pressure in the intake manifold (5) (generally about 580-670mmH
g) acts in the negative pressure chamber (14) and the differential pressure between the negative pressure and the atmospheric pressure on the atmosphere side passageway (8a) becomes larger than the pressing force of the spring (16), the valve (18) is set to open.

 Next, the operation will be described.

When the engine is driven, 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). To be done.
At this time, the atmospheric pressure in the intake pipe (3) acts in 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) is , Through the negative pressure passage (12) into the negative pressure chamber (14) in the vacuum limiter (7). And when the engine is idling,
Since the vacuum pressure in the intake manifold (5) is low (about 500 to 550 mmHg), the pressure difference between the atmosphere side passageway (8a) and the negative pressure chamber (14) is small. Therefore, valves (18)
Is pressed 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 closed operation state. Therefore, the air in the intake pipe (3) is prevented from detouring into the intake manifold (5) through the vacuum limiter (7). If the vehicle decelerates during high-speed running, the vacuum pressure in the intake manifold (5) becomes high (about 580 to 670 mmHg), so the atmosphere side passage (8a) and the negative pressure chamber (14) The pressure difference between
The negative pressure overcomes the pressing force of the spring (16),
The valve (18) is moved in the opening direction against the spring (16). At this time, when the inner protrusion (19) of the valve (18) is slightly separated from the seat surface (13), the atmospheric pressure in the atmosphere side passageway (8a) is immediately released from the gap and the outer protrusion () of the valve (18). It also acts on the second pressure receiving surface (23) surrounded by 20). Therefore, at the same time when 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 is rapidly increased from the state in which the valve (18) is slightly opened, and the air flow area formed between the valve (18) and the inner surface of the main body case (8) is rapidly increased. .
Therefore, the intake manifold (5) is passed through the vacuum limiter (7) from the intake pipe (3).
The flow rate of air flowing into the inside of the intake manifold rapidly increases, and the vacuum pressure in the intake manifold (5) decreases sharply.

In addition, the inner protrusion (19) of the valve (18) is formed in a line-pointed shape in order to improve the sealing property thereof, and when the flat seal structure is adopted, the valve (18) is pulsated by negative pressure.
This is because there is a problem in that the sound resonates to generate sound, and this problem is solved. Further, the outer projection (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. It is a thing. When the valve (18) is closed,
When the outer protrusion (20) is brought into close contact with the inner surface of the case (8),
When the negative pressure in the negative pressure chamber (14) changes after the valve (18) is closed, the negative pressure previously remains in the chamber of the second pressure receiving surface (23), and the proper valve operation is not performed. Because there will be problems
Always the space (23a) of the second pressure receiving surface (23) and the negative pressure chamber (14)
The above problem is solved by communicating with the above. When the gap (21) is enlarged, the atmospheric pressure acting on the second pressure receiving surface (23) easily escapes from the gap (21) to the negative pressure chamber (14). Set to a small amount. As a method for solving the above problems, as shown in FIGS. 3 and 4, the tip of the outer protrusion (19) is brought into contact with the inner surface of the main body case (8), and as shown in FIG. Forming a communication hole (21a) penetrating inward and outward in the outer protrusion (20),
Alternatively, as shown in FIG. 4, a communication groove (21b) penetrating inward and outward may be formed in the tip surface of the outer protrusion (20). Further, a communication hole that penetrates the valve (18) and the valve holding member (15) and communicates with the negative pressure chamber (14) from the bottom surface portion of the second pressure receiving surface (23) is formed with a small flow area. You may. According to the embodiment shown in FIG. 3, the chamber of the first pressure receiving surface (22) and the negative pressure chamber (1
4) It is easy and reliable to form a communication volume with. That is, in the embodiment shown in FIG. 1 and FIG. 2, when the contact position between the inner protrusion (19) and the seat surface (13) changes, the opening amount of the gap (21) also changes. Therefore, accuracy of the contact position at the time of assembling is required, but in the embodiment of FIG. 3, the flow rate of the communication hole (21a) does not change even if the contact position changes, so that the assembling is not possible. It will be easier.

FIG. 5 shows still another embodiment of the present invention, in which the inner protrusion (19) of the valve (18) in the embodiment shown in FIGS. 1 and 2 is replaced by an arc-shaped protrusion (19b). ) And the seat surface (13a) is formed into a square shape, the same operation and effect as in the embodiment shown in FIGS. 1 and 2 can be obtained in this embodiment. In this case, the protrusion (19b)
Surface (19c) is the first pressure receiving surface.

C. As described above, according to the present invention, the pressure receiving surface on which the pressure on the high pressure side acts is made small at the time of closing the valve and changed greatly at the early stage of opening the valve to make the opening operation sensitive at the early stage of opening the valve. It is possible to increase the opening amount and increase the supply air amount.
Therefore, when idling with a small differential pressure, the valve is 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. Moreover, the durability can be improved and the structure can be simplified and the cost can be reduced as compared with the one using the diaphragm.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention, FIG. 2 is a side sectional view of the same valve, and FIGS. 3 and 4 are main part sides showing another two embodiments of the valve. Sectional views, FIG. 5 is a side sectional view showing still another embodiment, and FIGS. 6 and 7 are conventional structure 2
It is each sectional side view which shows an example. (8a) …… Atmosphere side passage (9a) …… Negative pressure side passage (13) …… Seat surface (14) …… Negative pressure chamber (16) …… Spring (18) …… Valve (19) …… Inward protrusion Part (20) …… Outside protrusion (21) …… Gap that is a communication part (23a) …… Space

Claims (1)

[Claims] 1. A negative pressure chamber is provided in the body, and an atmosphere side passage communicating with the atmosphere is communicated with one end of the negative pressure chamber, and a negative pressure side passage communicating with an intake manifold is communicated with the other end of the negative pressure chamber. Is provided with a valve that can be opened and closed facing the seat surface formed in the atmosphere-side passage and is normally biased by a spring in the closing direction. In a valve closed state in which an inner protrusion that opens and closes the seat surface is provided on opposite surfaces, and an outer protrusion that is spaced apart from the inner protrusion is provided, and the inner protrusion contacts the seat surface. A vacuum limiter characterized by comprising a communication means for communicating the space formed by the inner protrusion and the outer protrusion and the negative pressure chamber with a small flow area.