JPH0432225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel pressure control device for a fuel injection device mainly employed in a vehicle engine.

(Prior Art) Fuel pressure control means in this type of fuel injection device include a pressure regulator that always maintains a constant difference between the fuel pressure applied to the injector and the intake negative pressure of the intake manifold, and a A pulsation damper is also used to absorb slight fluctuations in fuel pressure caused by fuel injection. These pressure regulators and pulsation dampers are each constructed individually and are installed at different locations relative to the fuel supply path (fuel supply pipe) to the injector (for example, Published on May 12, 2016 / Edited by Toyota Motor Corporation Service Department / See section 17. Delivery pipe, pulsation damper, pressure regulator” on page 3-76 of the Toyota Sprinter/Sprinter Trueno new model manual. ).

(Problems to be Solved by the Invention) In the above configuration, it is necessary to secure mounting space for each of the pressure regulator and the pulsation damper, and the assembly work becomes complicated. There is a risk that the responsiveness of the fuel pressure between the shear regulator and the pulsation damper may be reduced, and the fuel may be affected by the heat of the engine in the pipe that communicates them with each other.

(Means for Solving the Problems) In order to solve the above problems, the present invention is configured as follows.

That is, the fuel pressure control device of the present invention is a fuel injection device for an engine that supplies fuel in a fuel tank to an injector through a fuel supply pipe by operation of a pump. The diaphragm, the pressure regulator, and the pulsation damper are mutually integrated.

The fuel pressure chamber has a supply port that communicates with a fuel supply pipe downstream of the injector, and a return port that communicates with a fuel return pipe that communicates with the fuel tank.

The pressure regulator also includes a negative pressure chamber that is adjacent to the fuel pressure chamber via one of the two diaphragms and to which the intake pressure of the intake manifold acts, and a negative pressure chamber that is adjacent to the fuel pressure chamber through one of the two diaphragms. and a valve that controls opening and closing of the return port in conjunction with the operation of a diaphragm in response to a relative change with the intake pressure of the chamber.

Furthermore, the pulsation damper has an atmospheric chamber adjacent to the fuel pressure chamber via the other diaphragm, and is configured to absorb minute fluctuations in the fuel pressure within the fuel pressure chamber by operating this diaphragm.

According to this configuration, the pressure regulator and the pulsation damper are configured via diaphragms arranged on opposing surfaces within one fuel pressure chamber, so that the pump acting on the fuel pressure chamber Fine fluctuations in fuel pressure, such as fluctuations in discharge pressure and pressure fluctuations due to fuel injection from the injector, are absorbed by the pulsation damper, and the diaphragm of the pressure regulator is less susceptible to slight fluctuations in fuel pressure. Therefore, the diaphragm of the pressure regulator is actuated only by a large change in fuel pressure, and the return port is opened and closed by the valve linked thereto. Therefore, the fuel pressure adjustment function by the pressure regulator is stabilized.

(Example) Hereinafter, the structure of the present invention will be specifically explained according to an example shown in the drawings.

The second diagram shows the outline of the engine fuel injection system.
In the figure, from fuel tank A to each injector F
A filter B, a pump C, and a check valve D are installed in the route of the fuel supply pipe I leading to the fuel tank A.
are placed respectively. Further, in the route of the fuel supply pipe I, the injector F
A fuel control device consisting of a pressure regulator H and a pulsation damper E is incorporated on the downstream side.

FIG. 1 shows the fuel control device in cross-section. In FIG. 1, a body 1 made of die-casting or the like is located approximately in the middle in the vertical direction of the drawing.
are provided, and an upper cover 2 and a lower cover 15 are attached to the upper and lower surfaces of the body 1, respectively. A supply port 7 connected to the fuel supply pipe I described above is formed in the body 1, and a cylindrical return port 8 is also formed in the center of the interior of the body 1. This return port 8 has a connecting pipe 8a which is extended to the left in FIG.
A is connected to the aforementioned fuel tank A through a return pipe J shown in FIG. In addition, a plurality of holes 30 are formed in the reinforcing part 10 that connects the outer peripheral part of the return port 8 and the inner peripheral part of the body 1 inside the body 1 to allow fuel to flow upward and downward. It's open.

As can be seen from the above configuration, the interior of the body 1 includes the fuel tank A to each injector F.
It is configured as a fuel pressure chamber 6 which is subjected to the pressure action of the fuel supplied to the engine. Diaphragms 3 and 16 are disposed above and below this fuel pressure chamber 6, respectively, and the outer circumferential portions of both diaphragms 3 and 16 are sandwiched between the body 1 and each cover 2 and 15 at the joint portion thereof. It is fixed in a fixed position. A valve holder 4 and a shell 5 are attached to the center of the diaphragm 3 located above the fuel pressure chamber 6 so as to be integral with the diaphragm 3. At the center of the lower surface of the valve holder 4, that is, the surface facing the fuel pressure chamber 6, there is a valve 14 formed of an elastic material such as rubber or synthetic resin.
is fixed. As the diaphragm 3 moves, the valve 14 comes into contact with or moves away from the valve seat 9, which is the upper end surface of the return port 8, thereby opening and closing the return port 8.

Now, the internal space of the upper cover 2 adjacent to the fuel pressure chamber 6 via the diaphragm 3 is configured as a negative pressure chamber 11. This negative pressure chamber 11
is communicated with the intake manifold of the engine (not shown) through a negative pressure connection pipe 12 integrally formed with the top cover 2 and pipe G in FIG. is starting to come into play. Further, a compression spring 13 is installed between the shell 5 of the diaphragm 3 and the inner surface of the top cover 2 inside the negative pressure chamber 11, and the elasticity of this spring 13 causes the diaphragm 3 to 14 against the bubble sheet 9 (downward in FIG. 1).

In this way, the fuel pressure chamber 6, the negative pressure chamber 11, the diaphragm 3, and the valve 14 which controls the opening and closing of the return port 8 in conjunction with the operation of the diaphragm 3.
The pressure regulator H is composed of the following structural members. In addition, the above-mentioned valve seat 9 in this pressure regulator H
An auxiliary sheet 10a is formed on the outer peripheral portion of the auxiliary sheet 10a using a part of the auxiliary portion 10. This auxiliary seat 10a corresponds to the lower surface of the valve seat 9 on which the valve 14 is mounted so as to be able to come into contact with the lower surface of the valve seat 9. However, the above-mentioned valve 14 is set to slightly protrude from the lower surface of the valve holder 4, and in normal cases, the valve 14 first contacts the valve seat 9, and then the valve holder 4 contacts the auxiliary seat 10a. We will come into contact.

A diaphragm 1 located at the bottom of the fuel pressure chamber 6
A center core 17 and a shell 18 are both attached to the center of the diaphragm 6 so as to be integrated with the diaphragm 16. The tip of a pressure adjuster 19 slidably penetrated from the outside of the lower cover 15 is coupled to the center of the center core 17 with a screw. The inner space of the lower cover 15 adjacent to the fuel pressure chamber 6 via this diaphragm 16 is
It is configured as an atmospheric chamber 21 that communicates with the outside (atmosphere) by a plurality of ventilation holes 22 formed in the interior. A compression spring 20 is disposed within the atmospheric chamber 21 between the shell 18 and the inner peripheral surface of the lower cover 15, and the elasticity of this spring 20 causes the diaphragm 16 to always move upward as shown in FIG. is biased in the direction. The combination of the fuel pressure chamber 6, the atmospheric chamber 21, and the diaphragm 16 constitutes a pulsation damper E.

In the above configuration, if the difference between the fuel pressure acting on each injector F from the fuel supply pipe I and the intake negative pressure of the intake manifold becomes larger than a predetermined pressure (for example, if it becomes 2.55 Kg/cm ² or more) , the diaphragm 3 of the pressure regulator H moves upward in FIG. 1 against its spring 13. As a result, the valve 14 rises from the valve seat 9 and the fuel pressure chamber 6
The fuel return port 8 of is opened. As a result, excess fuel is removed from the return port J shown in Figure 2.
The fuel is returned to fuel tank A through the fuel tank A. As a result, when the difference between the fuel pressure in the fuel pressure chamber 6 and the intake negative pressure acting on the negative pressure chamber 11 becomes constant, the diaphragm 3
is pushed down by the action of the spring 13. Along with this, the valve 14 is pressed against the valve seat 9, which closes the return port 8, and the pressure regulator H keeps the difference between the fuel pressure and the negative intake pressure of the intake manifold constant. This function will be fulfilled.

In this way, the fuel pressure is always kept constant by the function of the pressure regulator H, but slight fluctuations (pulsations) occur in the fuel pressure due to the fuel injection from each injector F. . This slight fluctuation in fuel pressure acts on the diaphragm 16 of the pulsation damper E within the fuel pressure chamber 6, causing the diaphragm 16 to move in the vertical direction in FIG. For example, when the fuel pressure slightly decreases, the diaphragm 16 is moved upward in FIG.
The pressure shifts downward in FIG. 1 against this, thereby absorbing slight fluctuations in fuel pressure. This is the function of the pulsation damper E, which can suppress noise caused by minute fluctuations in fuel pressure.

Now, in this way, both the pressure regulator H and the pulsation damper E mentioned above function to always maintain the fuel pressure at an appropriate value.
It is desirable to set this fuel pressure to improve mutual responsiveness. In this embodiment, the above-mentioned fuel pressure chamber 6 serves as both the pressure regulator H and the pulsation damper E, so that the responsiveness of the fuel pressure between them is excellent. Also,
Unlike the one in which the pressure regulator H and the pulsation damper E are installed separately,
There is no need for a fuel pipe or the like to communicate these components with each other, which is advantageous in terms of the thermal influence of the engine on the fuel. Furthermore, by integrating the pressure regulator H and the pulsation damper E, the number of man-hours required for assembling them is reduced, and the fuel pipe piping and connectors that connect them to each other can be cut in half compared to conventional methods. It's over.

(Effects of the Invention) In this way, the present invention uses one fuel pressure chamber as both a pressure regulator and a pulsation damper, so that minute fluctuations in fuel pressure acting on this fuel pressure chamber can be handled by the pulsation damper. The pressure regulator opens and closes the return port accurately based only on large fluctuations in fuel pressure in the fuel pressure chamber, thereby stabilizing the fuel pressure adjustment function.

Further, according to the present invention, compared to the case where the pressure regulator and the pulsation damper are provided separately, it is easier to secure the assembly space, reduce manufacturing costs, and reduce the pressure regulator and the pulsation damper. The responsiveness of the fuel pressure between the generator and the pulsation damper is also improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a fuel pressure control device in an engine fuel injection device, and FIG. 2 is an explanatory diagram schematically showing the engine fuel injection device. 3, 16...Diaphragm, 6...Fuel pressure chamber, 7
...Supply port, 8...Return port, 14...
...Valve, E...Pulsation damper, F...
Injector, H...pressure regulator,
I...Fuel supply pipe, J...Return pipe.

Claims (1)

[Scope of Claims] 1. A fuel injection device for an engine that supplies fuel in a fuel tank to an injector through a fuel supply pipe by operation of a pump, comprising: a fuel pressure chamber; A diaphragm, a pressure regulator, and a pulsation damper are mutually integrated, and the fuel pressure chamber has a supply port connected to a fuel supply pipe downstream of the injector, and a fuel port connected to the fuel tank. a return port communicating with a return pipe, the pressure regulator is adjacent to the fuel pressure chamber via one of the two diaphragms, and is subjected to the intake pressure of the intake manifold. The pulsation damper has a negative pressure chamber and a valve that controls opening and closing of the return port in conjunction with the operation of a diaphragm in response to a relative change between the fuel pressure in the fuel pressure chamber and the intake pressure in the negative pressure chamber. an atmospheric chamber adjacent to the fuel pressure chamber via the other diaphragm;
A fuel pressure control device for an engine fuel injection device, characterized in that the diaphragm is operated to absorb slight fluctuations in fuel pressure within the fuel pressure chamber.