JPS6179093A - Pressure buffer device for absorbing pressure change in fuelsupply piping - 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 Field of the Invention The present invention relates to a pressure damping device for absorbing pressure fluctuations in a fuel supply pipe leading to a fuel injection device of a vehicle engine.

BACKGROUND OF THE INVENTION In a pressure buffer device used for such a purpose, a diaphragm is attached to the interior of a buffer housing formed by connecting a first housing member and a second housing member to absorb fuel. Conventionally, a type is known in which the diaphragm is divided into a first chamber that communicates with the supply pipe and a second chamber that accommodates a spring, and the diaphragm is pressed by the spring against a stopper provided in the first chamber. .

Problems to be Solved by the Invention With this plate pressure damping device, a problem occurs when the engine is stopped. In other words, when the engine is stopped, the fuel supply pump is of course stopped at the same time, but since the fuel supply pressure is maintained by the compressed spring in the shock absorber, the inward displacement of the diaphragm at that time exceeds a certain value. In some cases, fuel is injected into the engine combustion chamber and engine operation continues. In order to prevent this, conventionally, the spring biasing force is adjusted when manufacturing the shock absorber so that the amount of inward displacement of the diaphragm at a predetermined fuel pressure does not exceed a certain value.

However, despite the precise adjustment of the spring biasing force during the construction of the shock absorber, the amount of inward displacement of the diaphragm (at a given fuel pressure) actually varies considerably during operation, resulting in After the supply pump stops, a sufficient amount of pressurized fuel remains in the buffer, so
It was found that the engine continued to operate. This phenomenon is caused by the following reasons.

Normally, the spring biasing force is adjusted by inwardly deforming a part of the second housing member that defines the second chamber that accommodates the sub and ring while a fluid at a predetermined pressure is introduced into the first chamber of the buffer housing. This is done by moving the diaphragm inwardly, for example by about Q, 2 gff. Since the damping device is located in the fuel tank together with the fuel supply pump, the second chamber of the damping housing must be sealed.

Otherwise, fuel will enter the second chamber, causing corrosion problems, as well as uncontrollable pressure fluctuation absorption and undesirable noise caused by the vibration of the diaphragm. Since the chamber is sealed, when a portion of the second housing member is deformed inward as described above, the air pressure within the second chamber increases and therefore the force acting on the side of the diaphragm on the second chamber side increases. is determined by the sum of spring biasing force and air pressure. On the other hand, between the two housing members that constitute the buffer housing.

The outer edge of the diaphragm is clamped and fixed at the joint, but although this joint is liquid-tight, it is known that it is not completely airtight, and air leaks from the second chamber over time. As a result, the air pressure decreases, and therefore the reaction force (relative to fuel pressure) acting on the diaphragm also decreases. As a result, the amount of displacement of the diaphragm at a given fuel pressure increases, so even after the engine and fuel supply pump are stopped, more fuel than the allowable amount is supplied to the fuel injection device under pressure, causing the engine The operation will continue thereafter.

An object of the present invention is to provide a pressure buffer device that can solve the above conventional problems by keeping the initial reaction force applied to the diaphragm (reaction force when the diaphragm is not displaced) substantially constant over a long period of time. It's about doing.

Means for Solving the Problems In order to solve the above conventional problems, according to the present invention,
The buffer housing is provided with an orifice communicating with the second chamber.

Effect In the above configuration, even if the spring support point is displaced (the second housing member is deformed) in order to adjust the spring biasing force, the air pressure in the second chamber is maintained at atmospheric pressure via the orifice, so it will not decrease later. Even if the orifice is sealed and closed with a plug after adjusting the spring biasing force, if the change in air pressure in the second chamber due to temperature change is ignored, the initial reaction force applied to the diaphragm will be equal to the adjusted spring biasing force. It will be determined only by Furthermore, the influence of temperature changes can be completely eliminated by opening the orifice to the atmosphere outside the fuel tank through a venting conduit instead of sealing it.

Embodiments Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

The pressure damping device shown in FIG. 1 comprises a first housing member (1) and a second housing member (2) which are individually rotationally symmetrical and are interconnected by a beading extending between the two sides. It is equipped with a buffer housing consisting of. A diaphragm (4) is located between both housing members (f) (2).
The outer periphery of the diaphragm (4) is hermetically fixed to both housing members (1) and (2) by the connecting portion (3). The diaphragm (4) defines an interior of the buffer housing with a first chamber (5) defined by the diaphragm (4) and the first housing member (1), and a first chamber (5) defined by the diaphragm (4) and the second housing member (2). It is divided into a second chamber (6). The first housing part (1) is provided with a fuel inlet pipe (7), which communicates with a schematically illustrated fuel supply line (8). In addition, this distribution! ! Via F (8), fuel is supplied to a fuel injection device (not shown) of the vehicle engine by an intermittently operated fuel supply pump (9).

The pressure in the fuel supply line (8) is therefore introduced into the first chamber (5) via the inlet g (7) and acts on the negative side of the diaphragm (4). The upper end αO of the introduction pipe (7) forms a stopper portion of the diaphragm (4).A compression coil spring (B) acts on the other side of the diaphragm (4), and this spring (B) acts on the other side of the diaphragm (4). A receiver located in the second chamber (6) and attached to the diaphragm (4) at one end thereof abuts the plate @ and at the other end abuts the end wall of the second housing member (2).

The pressure buffering device having the above configuration is configured such that the fuel supply pipe (8) is caused by the intermittent pump operation of the fuel supply pump (9).
) (which can lead to considerable noise). When the engine and fuel pump (9) are stopped, fuel may be pushed out from within the shock absorber to the fuel injection device via the introduction pipe (7) and piping (8), and at this time, it is pushed out under pressure. When the amount of fuel exceeds a certain value, engine operation will continue for a while. In order to avoid this, attempts have been made to ensure a sufficient pressure fluctuation absorption effect even if the maximum displacement of the diaphragm (4) is small, and to maintain the fuel pushed out under pressure below a certain critical amount. . Therefore, when manufacturing the shock absorber, when a predetermined pressure of, for example, 6 bar is applied to the diaphragm (4), the maximum displacement of the diaphragm under this pressure is, for example, Q, 4j! It is common to adjust the biasing force of the spring (B) so that it becomes II. The spring biasing force can be adjusted, for example, by using the second housing member (2
) by deforming the end wall (to) downward (inward), or by pressing upward (inward) the introduction pipe (7) whose upper end αO functions as a stopper part, and by pressing the support point of the spring (j13). This can be done by displacing the

As mentioned above, in this type of conventional pressure buffer device, the second chamber (6) is kept in a sealed state because the device is placed inside the fuel tank. Therefore, when adjusting the spring urging force as described above, the air pressure increases at the same time as the volume of the second chamber (6) decreases. As a result, the initial reaction force that attempts to suppress the displacement of the diaphragm (4) is
It is determined by the sum of the urging force of the spring αp and the compressed air pressure in the second chamber (6).

However, because the joint (3) that clamps and fixes the outer edge of the tire flam (4) is normally liquid-tight, but not necessarily air-tight, the excess pressure in the second chamber (6) gradually dissipates. As a result, the initial reaction force applied to the tire slam (4) is reduced, and the diaphragm (4) under constant fuel pressure is reduced.
4) The amount of displacement increases. As a result, after the engine and fuel supply pump are stopped, the amount of fuel pushed out from the shock absorber becomes unacceptably large, resulting in continued operation of the engine.

In order to solve this problem, in the first embodiment of the present invention shown in FIG. 1, an orifice σ blue is provided in the second housing member (2), and the This is to prevent the air pressure in the chamber (6) from rising too high. Therefore, the initial reaction force applied to the diaphragm (4) is determined only by the biasing force of the spring αυ. After adjusting the spring biasing force, orifice 04
can be hermetically sealed with a stopper α9 fitted by soldering, for example. Since no excess pressure is generated in the second chamber (6), there is no loss of pressure, and it is possible to prevent the initial reaction force of the diaphragm (4), that is, the amount of displacement of the diaphragm (4) under a predetermined pressure from fluctuating. be.

In order to make the characteristics of all pressure buffer devices manufactured in series as constant as possible, it is necessary to eliminate the influence of atmospheric pressure fluctuations at the manufacturing site, but this is done by sealing and closing the orifice a→. 2nd room (6) prior to
This can be achieved by adjusting the internal pressure to a predetermined value.In the second embodiment shown in Q42H, instead of sealing and closing orifice α~ after adjusting the spring urging force, the It differs from that of FIG. 1 only in that it is open to the atmosphere outside the fuel tank (not shown) via a conduit Q5.

Although this configuration is slightly more expensive than the one in Figure 1,
There is an additional advantage that the pressure in the second chamber (6) is unaffected by changes in temperature.

Effects of the Invention As described above, in the pressure buffer device of the present invention, since the buffer housing is provided with an orifice that communicates with the second chamber, the increase in air pressure in the second chamber, that is, the air leakage caused by this over time, is prevented. Since the spring biasing force can be adjusted without any change, the initial reaction force of the diaphragm can be kept almost constant over a long period of time, which has the effect of preventing the engine from continuing to operate after the engine has stopped.

[Brief explanation of the drawing]

FIG. 1 shows lυ of a pressure buffer device according to a first practical example of the present invention.
[A top view and FIG. 2 are cross-sectional views of a pressure buffer device according to a second embodiment of the present invention. (1)...first housing member, (2)...second housing member, (3)...coupling portion, +4. )...Diaphragm, (5)...First chamber, (6)...m12
Chamber, (7)... Hijin pipe, (8)... Fuel supply pipe,
(9) Fuel supply pump, QO stopper part,
(B)...spring, αJ...end wall, α-
... Orifice, (to) ... Plug body, αG ... Conduit

Claims (1)

[Scope of Claims] 1. A pressure buffer device for absorbing pressure fluctuations in a fuel supply pipe disposed in a fuel tank and connected to a fuel injection device of a vehicle engine, comprising a buffer housing and the buffer. a diaphragm provided in the housing and dividing the interior into a first chamber and a second chamber communicating with the fuel supply pipe;
A spring provided in the second chamber between the end wall of the second chamber and the diaphragm, a stopper portion provided in the buffer housing so that the diaphragm is pressed by the spring, and a stopper portion that communicates with the second chamber. A pressure buffer device comprising: an orifice formed in a buffer housing. 2. Claim 1, wherein the orifice is hermetically closed by a plug after adjusting the biasing force of the spring.
Pressure buffer device as described in Section. 3. Claim 1, characterized in that the orifice is open to the atmosphere outside the fuel tank via a conduit.
Pressure buffer device as described in Section.