JPH11107885A - Flow rate control device and accumulator type fuel injection device using the flow rate control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate an assembly work for a flow rate control device, to perform reutilization of parts into which the flow rate control device is assembled after assembly, and to reduce a product cost. SOLUTION: Since no mechanical damage is exerted on housings 31 and 41 during release of screw-coupling of first and second housings 31 and 41, the reuse of parts, such as a compression coil spring 22, a supporter 23, a ball 24, and a piston 25, contained in the two housings 31 and 41 is practicable. Before coupling, the compression spring 22, the support 25, and the ball 24 are used in the first housing 31, and the piston 25 is previously assembled to a second housing 41. Thereafter, by screw-coupling together the two housings 31 and 41, assembly is easily completed. A flow limiter to satisfy performance within a desired specification is easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for controlling an excessive flow rate, for example, a fuel injection for an internal combustion engine in which high pressure fuel stored in a pressure accumulator is injected from a plurality of injectors at a predetermined timing. Applicable to the device.

[0002]

2. Description of the Related Art As means for supplying high-pressure fuel to a plurality of injectors provided corresponding to a plurality of cylinders of a multi-cylinder internal combustion engine, a so-called common rail type fuel injection for supplying high-pressure fuel stored in a pressure storage chamber to each injector. Devices are known. Such a pressure storage vessel as a common rail has an inlet side connected to a high-pressure supply pump via a high-pressure pipe, and an outlet side connected to a plurality of injectors via a plurality of pipes.

The fuel pumped from the fuel tank by the low-pressure supply pump is pressurized by the high-pressure supply pump, and the high-pressure fuel sent from the high-pressure supply pump is stored in a pressure storage container common to the cylinders. After that, fuel is supplied to the injector of the corresponding cylinder. At the outlet of the accumulator, a flow control device (hereinafter, “flow limiter”) for preventing an excessive amount of fuel from being supplied to the injector.
Is attached.

In this flow limiter, as shown in FIG. 3, for example, a screw portion 16 of a housing 21 is screwed to a fuel outlet of a pressure accumulator. The flow limiter 2 is assembled as follows as a single flow limiter before being screwed to the pressure accumulator. First, a compression coil spring 22 and a supporter 2 are provided inside a housing 21 having a basic cylindrical shape.
3. The ball 24 and the piston 25 are sequentially inserted, and the stopper 26 is finally press-fitted from the fuel inlet 51 side.

[0005]

According to this conventional flow limiter, the compression coil spring 2 as each of the above-mentioned components is mounted on a cylindrical housing 21 as an assembling step.
2. After assembling the supporter 23, the ball 24, and the piston 25 in order, a step of press-fitting the stopper 26 is required. Therefore, at least each of the above-mentioned components is inserted in the axial direction of the housing 21 in a vertical line. Since the mounting is performed, the mounting operation tends to be complicated.

Further, in the inspection process after the assembly, if the performance of the flow limiter 2 is determined to be out of the standard, removing the stopper 26 which is press-fitted and fixed to the housing 21 causes mechanical damage to a part of the housing 21. Not easy unless added. Therefore, the flow limiter 2 determined to be out of specification
If it is discarded, the components such as the compression coil spring 22, the supporter 23, and the ball 24 housed inside the housing 21 are not used even though they are compliant with the standard, so that the flow limiter as a product is not used. However, there is a problem that the cost increases. This raises the problem of cost increase when the defective product occurrence rate is high in the inspection process after the assembly of the flow limiter.

An object of the present invention is to facilitate assembly work,
An object of the present invention is to provide a flow limiter that enables reuse of parts disassembled and disassembled after assembling to reduce product cost.

[0008]

According to the flow control device of the present invention, a part or the whole of the flow control means is accommodated in the first housing, and the flow control means is controlled in the second housing. Because the structure to accommodate the rest of the means,
The housing can be easily assembled and disassembled. Further, since the housings are not mechanically damaged when the screw connection between the first housing and the second housing is released, the first housing and the second housing can be reused. For this reason, in the inspection after assembly, the first and second
By removing and attaching the screws, replacing part or all of the flow control means with another part, and reconnecting, it is possible to reuse parts that do not need to be replaced by replacing only part of the parts And the cost of the product can be reduced.

According to the flow control device of the second aspect of the present invention, by releasing the connection between the first housing and the second housing, the urging means, the supporter, the ball and the urging means accommodated in the two housings are released. Parts such as pistons can be reused. Since the first housing and the second housing are in a screw connection relationship, before the connection, a biasing means, a supporter and a ball are used in one housing, and a piston is pre-assembled in the other housing. Assembling is easily completed by screwing one housing and the other housing together.

At the time of disassembly, by releasing the screw connection between the first housing and the second housing, each part housed therein can be easily taken out. After removal, one or more of the urging means, the supporter, the ball, and the piston are replaced to easily assemble the flow limiter that satisfies the desired performance. By releasing the screw connection between the first housing and the second housing during the inspection, the first housing and the second housing can be reused to manufacture a flow limiter satisfying the performance within a desired standard. Easy.

According to the pressure accumulating fuel injection device according to the third aspect of the present invention, the supply pipe is provided at the outlet of the pressure accumulating vessel which supplies high pressure fuel to the plurality of injectors corresponding to each cylinder of the internal combustion engine via the supply pipe. Since the flow control device according to claim 1 or 2 is provided on the inlet side of the fuel injection system, a fuel injection system that can be downsized can be provided.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment showing an embodiment of the present invention will be described with reference to the drawings. (First Embodiment) FIGS. 1 and 2 show an embodiment in which the present invention is applied to a fuel injection device for a diesel engine.

In FIG. 2, a diesel engine (hereinafter, referred to as a diesel engine)
Injectors 5 are individually provided for the plurality of cylinders in the “engine” 4, and the injection of fuel from the injectors 5 into each cylinder is controlled by turning on and off an injection control solenoid valve 6. The injector 5 is connected to the pressure accumulating chamber 2 of the pressure accumulating vessel 1 common to the cylinders.
While the valve is open, the fuel in the accumulator 2 is
The fuel is then injected into each cylinder of the engine 4. Since it is necessary to continuously accumulate a high predetermined pressure corresponding to the fuel injection pressure in the accumulator 2, a high-pressure supply pump 9 is connected via a supply pipe 7 and a discharge valve 8. The high-pressure supply pump 9 pressurizes the fuel sucked from the fuel tank 10 via the known low-pressure supply pump 11 to a high pressure, and controls and maintains the fuel in the accumulator 2 at a high pressure.

The electronic control unit ECU 40 for controlling this system receives information on the number of revolutions and the load from, for example, the engine speed sensor 18 and the load sensor 19, and responds to the engine operating state determined from these signals. The ECU 40 outputs a control signal to each of the injection control solenoid valves 6 so that the determined optimum injection timing and injection amount (injection period) are obtained. At the same time, the ECU 40 outputs a control signal to the high-pressure supply pump 9 so that the injection pressure becomes an optimum value according to the rotation speed and the load.

Then, as shown in FIG.
Has a pressure accumulation chamber 2 as a fuel pressure accumulation passage formed therein in a straight line along the longitudinal direction. A fuel outlet 13 is formed in a direction perpendicular to the axis of the pressure accumulating chamber 2,
The flow limiter 12 is mounted between the fuel outlet 13 and the supply pipe 27. As shown in FIG. 1, the flow limiter 12 includes a first housing 31 and a second housing 41 whose housings can be divided.

The first housing 31 has a supply pipe 7 on its outer peripheral wall.
Are formed, and a male screw part 33 to be connected to the female screw part 48 of the second housing 41 is formed. First
Inside the housing 31, a fuel outlet 34, a spring hole 35 having a diameter larger than the fuel outlet, a guide hole 36 for accommodating the supporter 23, and a valve seat portion 5 capable of seating the ball 24 are provided.
5. A seal groove 38 for fitting the ball chamber 37 for accommodating the ball 24 and the seal ring 53 is formed. The inner diameters of the guide hole 36, the valve seat portion 55, the ball chamber 37 and the seal groove 38 increase in this order. Therefore, the inside of the first housing 31 can be easily processed. One end of the compression coil spring 22 contacts the shoulder 39 of the first housing 31, and the other end contacts the supporter 23.

The supporter 23 has a cylindrical basic shape, has a fuel passage 28 in the inner axial direction, and has an outer peripheral wall slidable in the axial direction on the inner wall of the guide hole 36 of the first housing 31. A contact surface 56 that supports the ball 24 at a plurality of points and a communication path 57 that constantly connects the ball chamber 37 and the fuel path 28 are formed at the end of the supporter 23 on the side of the accumulator. The ball 24 is housed in a ball chamber 37. This ball 24
Is normally in contact with the end face 58 of the piston 25 and also in contact with the contact face 56 of the supporter 23.

The basic shape of the piston 25 is a cylinder with a bottom.
An orifice hole 60 that constantly communicates the internal space 59 with the ball chamber 37 is formed eccentrically at the bottom. The piston 25 can slide back and forth in the axial direction on the inner wall of the sliding hole 47 of the second housing 41. One end of the piston 25 normally contacts the shoulder 49 of the second housing 41. Since the movement of the piston 25 in one direction is restricted by the shoulder 49, a component corresponding to a conventional stopper is not required.

The seal ring 53 is connected to the first housing 31.
To hold the ball chamber 37 in a liquid-tight manner. The second housing 41 has a screw portion 42 that is screw-connected to the pressure accumulator 1 and a female fitting portion 43 that can be screw-connected to the male screw portion 33 of the first housing 31. On the inner wall of the female fitting part 43, a female screw part 48 connectable to the male screw part 33 is formed. Inside the second housing 41, a fuel inlet hole 44, through holes 45 and 46 extending in the axial direction, a sliding hole 47 capable of reciprocating the piston 25, and a female female screw portion 48 are provided.
Are formed such that the inner diameter increases stepwise in this order. Therefore, since the second housing 41 has a shape in which the inner diameter increases stepwise in one direction in the axial direction, a hole can be easily formed at the time of manufacturing.

Next, a procedure for assembling the flow limiter 12 will be described. The compression coil spring 22, the supporter 23, the ball 24, and the seal ring 53 are housed inside the first housing 31, and these are used as a first component group. The piston 25 is housed in the sliding hole 47 of the second housing 41, and these are used as a second component group.

A seal ring 53 is fitted into the seal groove 38 of the first housing 31 in the first component group,
The female screw part 48 of the second housing 41 in the second component group assembled above is screwed to the male screw part 33 of the first housing 31. According to this assembling process, the first component group including the first housing 31 and the second component group including the second housing 41 are separately assembled and separately assembled, and then the two component groups are assembled. Attachment work can be performed easily.

At the time of inspection, when the inspection is performed after assembly, the screw connection between the male screw portion 33 of the first housing 31 and the female screw portion 48 of the second housing 42 is released. Then, each component of the compression coil spring 22, the supporter 33, the ball 24, and the piston 25 is easily taken out. In the inspection, when the performance of the flow limiter is determined to be out of specification, the part that causes the determination of out of specification is replaced with a new part, and reassembled in accordance with the above assembly process. For example,
When it is determined that the piston 25 is defective, only the piston needs to be replaced with a new piston, so that the compression coil spring 22, the supporter 23, and the ball 24 can be reused. Therefore, cost can be reduced by effective use of parts.

Next, the operation will be described. During normal operation,
As shown in FIG. 1, the piston 25 contacts the shoulder 49,
The ball 24 contacts the end face 58. At this time, ball 2
4 is located at the position of the maximum lift amount from the seat portion 55. The lift amount of the ball 24 changes according to the pressure difference between the internal space 59 of the piston 25 and the ball chamber 37. Normal time,
The ball 24 is separated from the seat portion 55. For example,
When a large amount of fuel flows from the accumulator 1 to the injector 5 via the flow limiter 12 due to damage to the injector 5, that is, when the fuel consumption becomes excessive, the ball 24 resists the urging force of the compression coil spring 22. The ball 24 and the supporter 23 are pushed down, and the ball 24 is eventually seated on the seat portion 55. Then, the fuel flow is cut off.
The maximum value of the fuel flow rate is basically determined by the piston length of the piston 25 and the orifice diameter of the orifice hole 60.

According to this embodiment, the axial length of the flow limiter 12 can be reduced as compared with the conventional one.
That is, since the piston 25 is described by the shoulder 49,
Since a stopper for stopping the piston 25 is not required, the axial length can be reduced. Further, since the first housing 31 and the second housing 41 are divided, the depth of drilling the inner wall of each housing stepwise in the depth direction from the opening can be shortened. The total axial length can be considerably reduced. That is, the size of the flow limiter can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a flow limiter according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an accumulator type fuel injection system to which the flow limiter shown in FIG. 1 is applied.

FIG. 3 is a sectional view showing a conventional flow limiter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Accumulator 4 Diesel engine 5 Injector 6 Solenoid valve for fuel injection 7 Supply piping 9 High pressure supply pump 12 Flow limiter (Flow control device) 22 Compression coil spring (Biasing means) 23 Supporter 24 Ball 25 Piston 31 First housing 33 Male screw part 34 fuel outlet 35 spring hole 36 guide hole 37 ball chamber 38 seal groove 41 second housing 43 male fitting part 44 fuel inlet hole 45, 46 through hole 47 sliding hole 48 female screw part 51 fuel outlet 53 seal ring 55 seat part

Claims (3)

[Claims] 1. A cylinder having a first housing having a valve seat portion on an inner wall and a first thread portion on an outer wall, and a second thread portion capable of being screw-coupled to the first thread portion. A second housing, and a flow regulating means which is housed in the first housing and the second housing and has a valve member which can be seated on the valve seat portion when the flow rate becomes excessive. Flow control device. 2. The flow rate regulating means is housed in the first housing and is capable of seating on the valve seat portion. A supporter is slidably housed in the first housing and supports the ball. An energizing means housed in the first housing and energizing the ball in a direction away from the valve seat portion; and an orifice hole capable of abutting the ball,
A piston that lifts the ball in a direction to seat the valve seat against the urging means when a differential pressure generated between an inlet and an outlet of the orifice hole increases. 2. The flow control device according to 1. 3. A pressure accumulating fuel injection device comprising: a pressure accumulator for accumulating high-pressure fuel; a plurality of injectors corresponding to each cylinder of the internal combustion engine; and a supply pipe connecting the pressure accumulator and the injector. 3. An accumulator type fuel injection device comprising the flow rate control device according to claim 1 or 2 provided at an outlet of the accumulator and at an inlet side of the supply pipe.