JPS6123651Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel pressure control device for controlling the pressure of injected fuel in an electronically controlled fuel injection device for an internal combustion engine.

A conventional fuel pressure control device of this type is shown in FIG. That is, about 5 kg/cm ² of fuel is pressurized from the fuel pump through the passage 17,
The A chamber of the fuel pressure control device 10 is press-fitted through the passage 14 . Further, the device 10 includes a diaphragm 1
The diaphragm 1
8 is now operational. When the fuel pump pressure is high, the fuel pressure in the A chamber overcomes the spring 13, the valve 12 is separated by the seat 11, and the fuel is returned to the tank through the passage 15. Further, when the fuel pressure is low, the valve 12 closes and the return amount decreases. By returning the fuel to the tank in this manner, the fuel pressure in the A chamber is controlled to a constant target value.

In this fuel pressure control device 10, when setting and adjusting the target value, the rear panel 16a of the cover 16 is bent and adjusted using a press or some kind of device. Since it is as large as 2 kg/mm, if the rear wall 16a is slightly bent, the pressure in the A chamber changes greatly, making it difficult to make fine adjustments and causing problems such as poor accuracy.

The purpose of the present invention is to solve the above-mentioned problems, namely, a part of the fuel supplied to the fuel injection device is returned to the tank side through a return passage via an on-off valve, and the on-off valve is In a device that is provided with a spring that is opened by fuel pressure and biased to close against the fuel pressure, one end of the spring engages with the valve 12 integrated with the diaphragm, and the other end is engaged with the valve 16 that is integral with the diaphragm.
One end of the outer spring is engaged with the valve 12 in the same manner as described above, and the other end is engaged with the spring guide 20.
and an inner spring engaged with the inner spring, and the spring constants of the outer spring and the inner spring are in the relationship of outer spring>inner spring, and the spring guide 20 engaged with the inner spring 21 is connected to the cover 16. It is characterized in that it is held by an adjuster screw 19 screwed in, and is provided with a device that applies an initial load to only the inner spring 21 of the inner and outer springs.

Next, an embodiment of the present invention shown in FIG. 2 will be described. Fuel, passage 17 from a fuel pump (not shown)
It passes through the fuel injection device 2 and enters the fuel chamber A of the fuel pressure control device 10 from the passage 14. The fuel injection device 2 injects fuel to achieve the optimum air-fuel ratio for each operating state of the internal combustion engine in response to signals from a computer. The fuel chamber A is equipped with a valve 12 on a diaphragm 18, and the valve 12 seals the seat 11 or separates from the seat 11 by operating the diaphragm 18. Then, due to the separating action of the valve 12, the fuel is transferred to the passage 1.
5, it is now returned to the tank. A large spring 13 is installed in the negative pressure chamber B of the fuel pressure control device 10 between the rear wall of the cover 16 and the diaphragm 18, and biases the diaphragm 18 in a direction that closes the seat 11. There is. Reference numeral 21 denotes a small spring, and the small spring 21 is installed on the adjuster screw 19 via a spring guide 20, and is connected to the large spring 13.
Similarly, the diaphragm 18 is urged in a direction to close the seat 11. The spring load of the small spring 21 is adjusted by an adjuster screw 19. Therefore, the diaphragm 18 is
The force pushing it to the side is the resultant force of the loads of the large and small springs 13 and 21. Although the two springs described above have one having a large spring constant and the other having a small spring constant, they may have the same spring constant. Negative pressure chamber B communicates with the manifold.

As described above, when the fuel pressure from the pump is high, the pressure in the fuel chamber A is increased by the springs 13 and 2.
1, the valve 12 is separated from the seat 11, the fuel is returned to the tank through the passage 15, and the fuel pressure is controlled to be constant. Fuel chamber A
The adjustment of the internal pressure is performed by applying an initial load to the inner spring 21, which has a smaller spring constant than the outer spring 13, by rotating the adjusting screw 19.

As described above, in the present invention, since fuel pressure control is performed using a plurality of springs, the spring constant of each spring is lower than that of the conventional system which uses one spring with a large spring constant. In addition to being able to set the spring to a small value, we also used springs with different spring constants, and because we adjusted the inner spring with the smaller spring constant, it was not easy to make fine adjustments; It has the advantage that the fuel pressure can be adjusted easily and accurately even when using the . In particular, in this invention, a device is provided that applies an initial load only to the inner spring, so the structure of the device is simple. That is, the adjuster screw 19 is formed by forming a protruding cylindrical body in the center of the rear wall of the cover, and carving a female screw into the cylindrical body.
It's easy to screw in.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional fuel pressure control device, and FIG. 2 is a sectional view showing an embodiment of the present invention. 10...Fuel pressure control device, 11...Seat,
12... Valve, 13, 21... Spring, 1
8...Diaphragm, 19...Adjustment screw.

Claims (1)

[Claims for Utility Model Registration] A portion of the fuel supplied to the fuel injection device is returned to the tank via a return passage via an on-off valve, and the on-off valve is opened by fuel pressure, and the fuel In the case where a spring is provided that urges the valve to close against pressure, the spring is connected to a valve 1 whose one end is integral with a diaphragm.
2 and the other end of which is engaged with the cover 16; and an inner spring whose one end is engaged with the valve 12 in the same manner as described above and whose other end is engaged with the spring guide 20. The spring constants of the outer spring and the inner spring are set in the relationship of outer spring>inner spring, and the spring guide 20 with which the inner spring 21 engages is held by the adjuster screw 19 screwed into the cover 16. A fuel pressure control device for a fuel injection device, characterized in that a device is provided to apply an initial load to only the inner spring 21 of the outer springs.