JPH06249094A - Pressure controlling valve - Google Patents

Abstract

PURPOSE:To provide a pressure controlling valve suited for control in a wide working region. CONSTITUTION:A plunger 10 of a proportional solenoid is disposed downstream of a seat part 3a of a valve seat in a pressure controlling valve. The plunger 10 is coupled with a core 15 through a rod 11. The core 15 is attracted by electrifying a coil 16 to displace the plunger 10 interlocked with the core 15 for throttling the fuel return side path. Thus, the reduction of fuel pressure in a low flow region can be corrected by the proportional solenoid. Further, since a diaphragm 4 can be miniaturized, an effect of improving a pressure resisting property is fulfilled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control valve for controlling a fuel pressure of an internal combustion engine, a mechanism for variably controlling a fuel passage area, and a control method therefor.

[0002]

2. Description of the Related Art A conventional pressure control valve has a function of performing excitation by a solenoid as a means for increasing fuel pressure at restart. As an example thereof, a pressure control valve such as that disclosed in Japanese Patent Publication No. 61-14334 (not shown) has been proposed. By the way, the above-described pressure control valve only opens and closes the fuel passage by driving the solenoid for a short period of time at the initial stage of valve opening, and pressure control after opening the valve is not considered. In the past, due to the characteristics of the pressure control valve, the controllability of the valve was poor in the low flow rate range, and there was the problem that the pressure dropped. Therefore,
In order to improve the controllability, a pressure control valve provided with a proportional solenoid that changes the stroke amount of the plunger by the applied current is proposed.

[0003]

The above-mentioned prior art only opens and closes the fuel passage only for a short time at the initial stage of valve opening, and cannot cope with pressure control in a low flow rate range.

In order to solve the above problems, an object of the present invention is to provide a pressure control valve equipped with a proportional solenoid that changes the stroke amount of a plunger by an applied current so that the fuel return passage area can be variably controlled. Especially.

[0005]

To achieve the above object, the back pressure of the fuel return passage is increased by displacing a plunger provided in the wake of the seat portion. Further, by making the plunger shape tapered, when the passage area is narrowed, the passage area changes gently, so that stable fuel pressure control can be performed.

[0006]

As described above, by transmitting the pressure to the fuel chamber through the seat portion serving as the throttle of the fuel return side passage, even if the pressure fluctuation occurs due to the movement of the plunger, it is alleviated and the pressure in the fuel chamber is affected. Never give. Further, since the stroke amount of the plunger can be made large, the control of the proportional solenoid becomes easy.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a cross-sectional view of an embodiment of a pressure control valve according to the present invention, in which reference numeral 3 is a body having an inlet passage 1 and an outlet passage 2, and a negative pressure passage 5 via a diaphragm 4. The outer peripheral portion of the casing 6 having the is wound and crimped.

The spring 7 presses the valve 9 against the seat portion 3a of the body through the plate 8 and the diaphragm 4. Immediately after the seat portion, a plunger 10 having a tapered tip shape is arranged, and is connected to a proportional solenoid via a rod 11 connected to the plunger. The casing 12 of the proportional solenoid and the outer contact surface of the body are kept airtight by an O-ring 13. A seal ring 14 is provided on the inner contact surface so that the plunger can slide and keep airtight.

The rod 11 is connected to the core 15,
A bush 17 for attracting the core when energized is arranged inside the coil 16. The spring 18 is arranged between the solenoid casing 12 and the core 15, and presses the core against the adjusting screw 19.

Next, the structure of the valve portion will be described with reference to FIG.

The rubber diaphragm 4 has a three-layer structure in which a base cloth and both sides thereof are sandwiched by rubber, and convex portions 4a and 4b are provided on both sides of a radial intermediate portion on the circumference of the diaphragm. A groove is provided on the circumference of the contact surface between the sandwiching valve 8 and the plate 9 at a position where it engages with the protrusions 4a and 4b, and the groove engages with the protrusions 4a and 4b of the diaphragm. This prevents the radial deviation from occurring. The seat surface of the valve is ground so as to maintain oil tightness when seated on the seat portion 3a of the body. The valve spring 20 presses the valve so as to follow the diaphragm when the valve is opened. With this structure,
Conventionally, a hole is provided in the central portion of the diaphragm 4 and a member is inserted into the hole to prevent the radial deviation. On the other hand, the valve, the diaphragm and the plate constitute the center disk portion. The number of parts is reduced and the assembly becomes easier.

Next, the operation of this embodiment will be described.

Fuel pumped by the fuel pump 21 shown in FIG. 3 flows in through the inlet passage 1. Next, when the fuel chamber 1a is filled with fuel and the fuel pressure rises, the center disk portion is displaced toward the air chamber 6a side so that the product of the fuel pressure and the diaphragm pressure receiving area balances with the spring load. As a result, the seat portion is opened, and the fuel is returned to the fuel tank 22 through the outlet side passage 2 so that the fuel pressure is controlled to a predetermined value.

Here, in the conventional pressure control valve, as shown by the broken line in FIG. 4, the controllability of the valve deteriorates in the low flow rate region, and a pressure drop occurs.

The pressure control valve of the present invention corrects this pressure drop in the low flow rate region. Therefore, when the pressure falls below a certain set pressure, the proportional solenoid is driven to displace the plunger, thereby narrowing the outlet side passage and reducing the fuel chamber. Operates for higher pressure.

A pressure sensor 23 is arranged on the inlet passage side of the pressure control valve to measure the fuel pressure. The fuel pressure data measured by the pressure sensor is input to the control unit 24. Here, when the fuel pressure becomes equal to or lower than a predetermined pressure (for example, 5% lower than the adjusted pressure), a drive current signal is output from the control unit to the proportional solenoid portion of the pressure control valve to displace the plunger. In this way, feedback control is performed to reduce the drop in fuel pressure in the low flow rate range.

[0018]

Since the present invention is constructed as described above, it has the following effects. In the past, there was a drop in pressure in the low flow rate region, which could affect the atomization of fuel in the fuel injection valve. In the present invention,
By driving the proportional solenoid and narrowing the passage on the outlet side,
This pressure drop can be corrected. As a result, the pressure is maintained even in the low flow rate region, so that atomization of the fuel injected from the fuel injection valve is promoted, and there is an advantage that the emission is improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a pressure control valve according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a center disk unit.

FIG. 3 is a fuel system diagram of an internal combustion engine using the pressure control valve of the present invention.

FIG. 4 is a characteristic diagram of the pressure control valve of the present invention.

[Explanation of symbols]

4 ... diaphragm, 8 ... plate, 9 ... valve, 10 ...
Plunger, 14 ... Seal ring.

Claims (3)

[Claims] 1. A fuel chamber and an air chamber are formed by partitioning a body having an inlet passage and an outlet passage and a casing having an air passage by a diaphragm, and a central portion of the diaphragm responds to pressure fluctuations in the fuel chamber. In the pressure control valve for opening and closing the seat portion by the displacement of the valve element arranged in the above, a pressure control valve is provided in which a fuel return side passage area is variable by disposing a plunger in the downstream of the seat portion. 2. The pressure control valve according to claim 1, wherein the plunger is driven by a proportional solenoid. 3. A diaphragm according to claim 1, wherein a convex portion is provided in a circumferential direction on both surfaces of a radial intermediate portion of the diaphragm, and the diaphragm is engaged with the convex portion by a center disk having two groove portions. The pressure control valve is characterized in that the diaphragm is supported so as to be overlapped with each other.