JP2000199577A - Check device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dust in the atmosphere from entering a negative pressure part and adhering thereto when the negative pressure valve of a check valve is opened as a result of the internal part of a fuel tank being brought into a negative pressure. SOLUTION: When a negative pressure in a fuel tank is increases to a valve higher than a constant value, a negative pressure valve 18 is moved as shown in a drawing against a spring 19 and opened. The atmosphere enters, as shown in a drawing, a first atmosphere introduction chamber 22 through an atmosphere introduction port 20 for dispersion. The atmosphere is throttled by a communication hole 21 and enters a second atmosphere introduction chamber 22 for dispersion. The atmosphere flows through the periphery of the opened negative pressure valve 18 and flows to the right in a Fig. to control an internal pressure in a fuel tank. When dust entering togetherwith the atmosphere enters the two atmosphere introduction chambers 22 and 23, it is dispersed and hardly adhered to the negative pressure valve part. Reliability on the check valve is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement of a check valve connected to a fuel tank.

[0002]

2. Description of the Related Art Conventionally, a check valve is connected to a fuel tank in order to prevent the tank from cracking when the internal pressure of the fuel tank rises and to protect the tank.

This check valve opens a positive pressure valve at a specified value when the tank fuel pressure rises and the tank internal pressure becomes a positive pressure, and opens a negative pressure valve at a specified value when the tank fuel pressure decreases and the tank internal pressure becomes a negative pressure. Opens to control the tank internal pressure, prevent the tank from cracking and protect the fuel tank.

FIG. 4 shows the structure of this type of check valve. A cover 2 having a connection pipe 2a connected to a canister (not shown) on the atmosphere side is welded to an end surface of a case 1 having a connection pipe 1a connected to a fuel tank (not shown). Reference numeral 3 indicates this welded portion.

[0005] A positive pressure valve 4 has a tubular member 5 fitted and welded to the inner surface thereof. Reference numeral 6 indicates this welded portion.
The positive pressure valve 4 is biased rightward in the figure by a positive pressure spring 7,
It is in contact with the positive pressure sealing surface 1b formed in the case 1.

Reference numeral 8 denotes a negative pressure valve inserted inside the member 5, which is urged leftward in the figure by a negative pressure spring 9 and abuts against a negative pressure sealing surface 5 a formed on the member 5. Reference numeral 10 denotes an air inlet.

[0007] The position of the seal of the negative pressure valve 8 and the position of the atmosphere inlet 10 are coaxial and opposed to each other. Also, the negative pressure valve 8
The diameter φd of the spherical portion and the gap L are configured to have substantially the same size (φd ≒ L). The gap L is the distance between the end face of the cover 2 at the atmosphere inlet 10 and the left end of the sealing surface 5a constituting the negative pressure valve 8, in fact, the negative pressure valve portion.

[0008]

In the above prior art,
Since the seal position of the negative pressure valve 8 and the position of the air inlet 10 are coaxial and have a structure of φd ≒ L, the gap L between the end face of the cover 2 of the air inlet 10 and the negative pressure valve 8 becomes small, and Space volume is small.

Therefore, when the internal pressure of the fuel tank becomes a negative pressure and air containing dust is introduced, the dust coming from the air inlet 10 directly enters the opposed / coaxially arranged negative pressure valve portion and adheres thereto. However, there is a problem that a defective seal is likely to occur.

Accordingly, an object of the present invention is to provide a check valve which can solve such a problem.

[0011]

According to a first aspect of the present invention, there is provided a coaxial two-way check valve, wherein a first and a second valve are disposed between an atmosphere inlet position and a negative pressure valve portion seal position. 2
A check valve is characterized in that the air introduction chambers are arranged in order, and a communication hole communicating between the air introduction chambers is provided between the two air introduction chambers.

Even if dust enters from the air inlet with the atmosphere when the negative pressure valve is opened, the dust is diffused in the first and second air introduction chambers, so that the amount of dust entering the negative pressure valve portion is reduced. According to a second aspect of the present invention, in the check valve of the first aspect, an interval between the position of the air inlet and the position of the negative pressure valve seal is set to be at least twice the ball diameter of the negative pressure valve. .

According to the present invention, since the distance between the position of the air inlet and the position of the negative pressure valve seal can be made relatively large, the volumes of the first and second air inlet chambers become large, and the amount of dust reduced by diffusion. Not only is increased, but also the chance of dust directly entering the negative pressure valve section is reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to FIGS.

The check valve 100 constitutes a coaxial two-way check valve as in the prior art, and is disposed and connected between the fuel tank 101 and the atmosphere so that the internal pressure of the fuel tank exceeds a specified value. Prevent pressure and control the tank internal pressure to protect the fuel tank.

When the difference between the internal pressure of the fuel tank 101 and the atmospheric pressure is small, both the positive pressure valve 14 and the negative pressure valve 18 of the check valve 100 are closed, as shown in FIGS.
When the negative pressure in the fuel tank 101 increases beyond a specified value, the negative pressure valve opens as shown in FIG.

The case 11 has its connection pipe 11a communicated with the atmosphere through a canister (not shown) or directly to the atmosphere. The cover 12 is welded to the end face of the case 11 at a welding portion 13, and the integrally formed connection pipe 12 a is connected to the fuel tank 101 via a pipe 102.

The positive pressure valve 14 is urged rightward in the figure by a positive pressure spring 17 and abuts against the seal surface 12b of the cover 12 to be closed. The ball-shaped negative pressure valve 18 made of metal or resin is urged leftward by a negative pressure spring 19 to
(FIG. 1 and FIG. 3). It should be noted that the ball-shaped negative pressure valve 18 and the sealing surface 14a for negative pressure constitute a negative pressure valve portion.

The distance L between the air inlet 20 at the right end of the connecting pipe 11a and the negative pressure sealing surface 14a, which is the sealing position of the negative pressure valve section, is set to be at least twice the diameter φd of the ball-shaped negative pressure valve 18. It is convenient to use 2 to 4 times. And
A communication hole 21 having a small diameter is formed in the partition wall 14b of the positive pressure valve 14.

A first space is provided between the air inlet 20 and the partition 14b.
An air introduction chamber 22 is formed between the partition wall 14b and the negative pressure valve 18, and a second air introduction chamber 23 is formed.
The space 23 communicates with the communication hole 21.

When the negative pressure in the fuel tank 101 exceeds a specified value, the negative pressure valve 18
Move to the right and open. Then, the air inlet 20
The air introduced as indicated by arrow A diffuses into the first introduction chamber 22, is narrowed by the communication hole 21, and then diffuses into the second air introduction chamber 23. Then, the fuel is passed through the open negative pressure valve 18 and introduced into the fuel tank 101 to protect the tank by controlling the internal pressure of the fuel tank so as not to become a large negative pressure.

[0022]

Since the check valve of the present invention is constructed as described above, dust entering with the atmosphere when the negative pressure valve is opened is reduced from adhering to the negative pressure valve, and the reliability of the check valve is improved. can do.

According to the second aspect, the effect is further enhanced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2 is a view for explaining a mode when the negative pressure valve is opened in the embodiment of FIG. 1;

FIG. 3 is a system diagram in which the check valve of FIG. 1 is connected to a fuel tank.

FIG. 4 is a longitudinal sectional view of a conventional check valve.

[Explanation of symbols]

Reference Signs List 11 Case 12 Cover 14 Positive pressure valve 14a Negative pressure sealing surface 14b Partition wall 18 Ball-shaped negative pressure valve 19 Negative pressure spring 20 Atmospheric introduction port 21 Communication hole 22, 23 Atmospheric introduction chamber 100 Check valve 101 Fuel tank φd Ball diameter of negative pressure valve L Interval between the air inlet end face position and the negative pressure valve seal position

Claims (2)

[Claims] In a coaxial two-way check valve, first and second air introduction chambers are sequentially disposed between an air introduction port position and a negative pressure valve section sealing position, and two air introduction chambers are provided between the two air introduction chambers. A check valve characterized by having a communication hole communicating with the air introduction chamber. 2. The check valve according to claim 1, wherein the distance between the position of the air inlet and the position of the negative pressure valve portion seal is set to be at least twice the diameter of the negative pressure valve ball.