JPH01242896A - Pulsation absorbing device - Google Patents

Abstract

PURPOSE:To prevent the change in a pulsation damping factor by making up a case of a damper chamber and a pressure chamber, and providing a pressure introducing port, an armature, and a coil spring, and by introducing the negative pressure in a pressure accumulator to the pressure introducing port. CONSTITUTION:A case 13 is made up of a damper chamber 11, and a pressure chamber 12. On the damper chamber 11 side, a fuel introducing port 14 and a fuel discharge port 15 are provided, and on the pressure chamber 12 side, a pressure introducing port 19 is provided. A diaphragm 21 is stretched so as to partition the inside of the case 13 into two chambers, and an armature 22 is arranged to the diaphragm 21 so as to be inserted in the damper chamber 11, while a coil spring 23 for energizing the armature 22 toward the damper chamber 11 side is provided. Further, it is so constituted that the negative pressure in a pressure regulator is introduced to the pressure introducing port 19. As a result, even if the fuel pressure in the pressure regulator fluctuates, the change in a pulsation damping factor can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pulsation absorbing device for absorbing pulsation of a pump, and particularly relates to a technique for preventing a decrease in damping rate. Concerning what is effective for use in fuel pumps.

[Conventional technology]

In an engine fuel supply system, it is desirable to supply fuel at as constant a pressure as possible. Therefore, a pulsation absorbing device is connected to the discharge side of the fuel pump that pumps fuel to absorb the pulsations in the discharge pressure (
For example, Utility Model Application No. 55-20687, Utility Model Application No. 57-44
See No. 973 and Utility Model Application Publication No. 18260/1983. ).

Conventionally, in this type of device, the fuel inlet is connected to the fuel pump side via the fuel passage, and the fuel outlet is connected to the fuel injection valve side via the fuel passage, and the system responds to pressure changes in the damper chamber. The pulsation of the fuel pump is absorbed by changing the volume of the damper chamber by moving the diaphragm back and forth.

[Problem to be Solved by the Invention] By the way, in the negative pressure chamber of the pressure regulator for maintaining the pressure of the fuel supply system in which the fuel pump is installed at a constant pressure, there is an intic negative pressure ~ during idling as fuel pressure. 0.6kg/a! .

Turbo boost pressure +0.8kg/cJ etc. will be applied. When the set pressure is 2.55 kg/cd, this pressure is 1.9 kg/c~3.3 kg/ctK with respect to atmospheric pressure. This pressure change is transmitted to the damper chamber of the pulsation absorber as a change in fuel pressure.

In conventional pulsation absorbers, the pressure chamber is open to the atmosphere, so the pressure difference between the atmospheric pressure and the pressure in the negative pressure chamber of the pressure regulator is directly transmitted to the damper chamber of the pulsation absorber as fluctuations in fuel pressure. transmitted, resulting in
In the pulsation absorbing device, the diaphragm that essentially performs the damping action is greatly bent in one direction, which causes the problem that the diaphragm loses its slack and the pulsation attenuation rate decreases.

An object of the present invention is to provide a pulsation absorbing device that can prevent a decrease in the pulsation attenuation rate.

[Means to solve the problem]

The pulsation absorbing device according to the present invention includes a case that constitutes a damper chamber and a pressure chamber, a fuel inlet and a fuel outlet that are opened on the damper chamber side of the case, and a fuel outlet that is opened on the pressure chamber side of the case. A diaphragm is stretched between the pressure inlet, the damper chamber and the pressure chamber so as to divide the inside of the case into two chambers, an armature is supported by the diaphragm and inserted into the damper chamber, and a The fuel inlet is connected to the fuel pump via the fuel passage, and the fuel outlet is connected to the fuel pump via the fuel passage. A pulsation absorbing device connected to the injection valve side and configured to absorb pulsations of the fuel pump by changing the volume of the damper chamber by advancing and retreating a diaphragm that responds to pressure changes in the damper chamber, The present invention is characterized in that negative pressure in a negative pressure chamber of a pressure regulator that keeps the pressure in the fuel passage constant is introduced into the pressure introduction port.

[Effect]

According to the above-described means, fuel is fed into the damper chamber as the fuel pump operates. At this time, when the pressure in the damper chamber decreases due to the pulsation, the diaphragm is lowered by the biasing force of the coil spring, operating in a direction to reduce the volume of the damper chamber. This reduction in volume acts to suppress the pressure in the damper chamber from decreasing due to pulsation.

On the other hand, when the decreasing tendency of the pressure in the damper chamber changes to an increasing tendency as the pulsation progresses, the diaphragm is lifted as the pressure increases, and the volume of the damper chamber increases. This increase in volume acts to suppress the pressure in the damper chamber from increasing. Therefore, pressure fluctuations in the damper chamber can be suppressed due to changes in the volume of the damper chamber due to the movement of the diaphragm. That is, pressure fluctuations in the damper chamber are absorbed by the movement of the diaphragm, and pulsations in the fuel pump connected to the damper chamber via the fuel passage are smoothed out.

Furthermore, even if the pressure in the negative pressure chamber of the pressure regulator changes, the pressure chamber of the pulsation absorber is also supplied with negative pressure from the negative pressure source that communicates with the negative pressure chamber of the pressure regulator. If the fuel pressure fluctuates greatly due to operation, the pressure inside the pressure chamber of the pulsation absorber will also change to follow this fluctuation.
This prevents the pulsation damping rate from decreasing due to changes in fuel pressure.

C Embodiment] FIG. 1 is a longitudinal sectional view showing a pulsation absorbing device which is an embodiment of the present invention, FIGS. 2 and 3 are longitudinal sectional views for explaining its operation, and FIG. FIG. 1 is a fuel pressure characteristic diagram of the pulsation absorbing device, and FIG. 5 is a fuel pressure characteristic diagram of the pressure regulator.

In this embodiment, a fuel damper 10 as a pulsation absorbing device according to the present invention includes a case 13 having a damper chamber 11 and a pressure chamber 12, and a fuel inlet port is provided on the side wall of the case 13 on the damper chamber 11 side. 14 and fuel outlet 15
They are arranged so that they are facing each other. An inlet pipe 16 constituting a fuel passage is connected to the fuel inlet 14, and this pipe 16 is connected to the fuel pump side. An outlet pipe 17 constituting a fuel passage is connected to the fuel discharge port 15, and this pipe 17 is connected to the fuel injection valve side. The pipe 16 allows fuel from the fuel pump to flow into the damper chamber 11.
The fuel in the damper chamber 11 is supplied to the fuel injection valve via a pipe 17.

A mounting bracket 18 is provided on the bottom wall of the case 13 to securely attach the fuel damper 10 to a machine frame or the like (not shown).
is installed. On the other hand, a pressure introduction port 19 is provided in the ceiling wall of the pressure chamber 12 of the case 13, and a pipe 20 as a pressure introduction pipe is connected to this pressure introduction port 19. This pipe 20 is connected to an inner manifold (not shown) of the engine intake system, and intake pressure is introduced into the pressure chamber 12 through this pipe 20.

The case 13 has a pressure chamber 12 and a damper chamber 1 inside the case 13.
A diaphragm 21 for dividing the case 13 into two is movably stretched, and the periphery of the diaphragm 21 is fixed to the inner wall surface of the case 13.

An armature 22 is floatingly supported by the diaphragm 2I, and the armature 22 is urged toward the damper chamber 11 by a coil spring 23 inserted into the pressure chamber 12. That is, the upper end of the coil spring 23 is brought into contact with the ceiling surface of the pressure chamber 12, and the lower end is brought into contact with the armature 22 via the spring seat 24, so as to urge the armature 22 toward the damper chamber 11 side. There is. The spring seat 24 is brought into contact with the upper surface of the diaphragm 21 and can move together with the diaphragm 21 and the armature 22 while holding the diaphragm 21 therebetween.

Next, the effect will be explained.

First, when the fuel pump is operated, fuel is pumped through the inlet pipe 16, damper chamber 11, and outlet pipe 17 to the fuel injection valve. As the fuel pump operates, a pulsation phenomenon, which is a periodic pressure fluctuation, occurs on the discharge side of the fuel pump. This pulsation phenomenon is also propagated to the damper chamber 11 filled with fuel.

Now, if the pressure inside the damper I (corresponding to the discharge pressure of the fuel pump) decreases due to the pulsation phenomenon, the balance between the coil spring 23 and the force exerted by the fuel pressure inside the damper chamber 11 will be lost. , the diaphragm 21 is displaced downward, as shown in FIG. That is, the diaphragm 21 is lowered by the biasing force of the coil spring 23, thereby decreasing the volume inside the damper chamber 11. This decrease in volume is caused by the pressure in the damper chamber 11 decreasing due to pulsations. acts to suppress

When the decreasing tendency of the pressure in the damper chamber 11 changes to an increasing tendency as the pulsation progresses, the force acting against the coil spring 23 increases as the pressure increases, so that the state shown in FIG. 2 changes from the state shown in FIG. 1. The diaphragm 2I is lifted to this state, and the volume of the damper chamber 11 is increased. This increase in volume acts to suppress the pressure in the damper chamber 11 from increasing.

Furthermore, when the pressure in the damper chamber 11 increases due to pulsation, the balance between the biasing force of the coil spring 23 and the pushing force due to the fuel pressure in the damper chamber 11 is lost.
As shown in the figure, the diaphragm 11 rises against the urging force of the coil spring 23, thereby increasing the volume of the damper chamber 1. This increase in volume acts to suppress the pressure in the damper chamber 11 from increasing due to pulsations.

As the pulsation progresses, the pressure in the damper chamber 11 changes from an increasing tendency to a decreasing tendency, and as the pressure decreases, the restoring force of the coil spring 23 pushes the diaphragm 21 downward from the state shown in FIG. 3 to the state shown in FIG. Therefore, the volume of the damper chamber 11 will be reduced. This reduction in volume acts to prevent the pressure in the damper chamber 11 from decreasing.

In this way, the damper chamber 1 is moved by moving the diaphragm 21 back and forth.
1 acts in the direction of suppressing the pressure fluctuations in the damper chamber 11. Therefore, the pressure fluctuations in the damper chamber 11 are absorbed by the movement of the diaphragm 21, and the outlet in the outlet pipe 17 of the damper chamber 11 is absorbed. The side pressure and the pulsations in the supply pressure to the engine connected thereto are smoothed out.

Here, when the operating state of the engine is idling or turbocharging, the fuel pressure of the pressure regulator will be lower than the normal operating state, as shown in Figure 5. The fuel pressure also changes significantly. This pressure fluctuation is then propagated to the fuel in the damper chamber 11 via the outlet vibe 17.

However, since the pressure chamber 12 in this embodiment is connected to the intake manifold via the pipe 20,
An intic negative pressure is introduced into the pressure chamber 12, and as shown in FIG. 4, the pressure within the pressure chamber 12 changes in accordance with changes in the fuel pressure of the pressure regulator. That is, since a change in the fuel pressure of the pressure regulator directly appears as a change in the pressure in the pressure chamber 12, the pressure in the pressure chamber 12 changes in accordance with the fluctuation in the fuel pressure in the damper chamber 11. As a result, the diaphragm 21 is always maintained in a horizontal state, and it is possible to suppress a decrease in the pulsation damping rate due to fluctuations in fuel pressure.

Note that the present invention is not limited to the above embodiments,
It goes without saying that various changes can be made without departing from the gist of the invention.

For example, the pressure chamber is not limited to being connected to the intake manifold, but may also be connected to the negative pressure chamber of the pressure regulator or a pipe line in the middle.In short, the negative pressure used to control the pressure regulator absorbs pulsation. What is necessary is just to configure it so that it is substantially supplied to the pressure chamber of the device.

〔Effect of the invention〕

As explained above, according to the present invention, since the negative pressure of the pressure regulator is introduced into the pressure chamber, it is possible to prevent the pulsation damping rate from changing even if the fuel pressure of the pressure regulator fluctuates. can.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a pulsation absorbing device which is an embodiment of the present invention, FIGS. 2 and 3 are vertical cross-sectional views for explaining its operation, and FIG. FIG. 5 is a fuel pressure characteristic diagram of a pressure regulator. 10... Fuel damper, ll... Damper chamber, 1
2... Pressure chamber, 13... Case, 14... Fuel inlet, 15... Fuel outlet, 16... Inlet pipe, 17... Outlet vibe, 19... Pressure inlet , 20... Intake manifold connection pipe (negative pressure introduction path), 21... Diaphragm, 22...
・Armature, 23...Coil spring, 24・
・Spring seat.

Claims (1)

[Claims] 1. A case that constitutes a damper chamber and a pressure chamber, a fuel inlet and a fuel outlet opened on the damper chamber side of the case, a pressure inlet opened on the pressure chamber side of the case, and a damper chamber. A diaphragm is stretched between the housing and the pressure chamber to divide the case into two chambers, an armature is supported by the diaphragm and inserted into the damper chamber, and a spring seat is placed inside the pressure chamber. The fuel inlet port is connected to the fuel pump side via the fuel passage, and the fuel discharge port is connected to the fuel injection valve side via the fuel passage. The pulsation absorbing device is configured to absorb pulsation of the fuel pump by changing the volume of the damper chamber by advancing and retracting a diaphragm that is sensitive to pressure changes in the damper chamber, and the pressure in the fuel passage is adjusted. A pulsation absorbing device characterized in that the negative pressure in a negative pressure chamber of a pressure regulator is introduced into the pressure introduction port.