JP3638297B2 - Safety valve for fuel injector - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a fuel injection device for an internal combustion engine in which high pressure fuel stored in a pressure accumulating chamber is injected from a plurality of injectors.
[0002]
[Prior art]
As a 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 device that supplies high pressure fuel stored in a pressure accumulating chamber to each injector is known. Yes.
As this type of common rail fuel injection device, one disclosed in Japanese Patent Application Laid-Open No. 4-72455 is provided with a pressure limiter that functions as a safety valve in the pressure accumulation fuel injection device. This pressure limiter opens when the pressure in the pressure accumulating chamber in the common rail becomes excessive, and releases the fuel pressure by letting the fuel escape from the pressure accumulating chamber.
[0003]
[Problems to be solved by the invention]
However, in an accumulator fuel injection device equipped with such a pressure limiter, the life may be ended without opening the pressure limiter even after the accumulator fuel injection device is mounted on the internal combustion engine. For example, if such a pressure limiter is not opened for a long period of time, rust is generated on the downstream side of the seat on which the valve element is seated. There is a risk that it will not be possible.
[0004]
The present invention has been made in order to solve such problems, and the fuel is constantly immersed in the downstream portion of the seat of the pressure limiter so that rust generation is suppressed, so that the valve can be opened without being used for a long period of time. An object of the present invention is to provide a highly reliable safety valve for a fuel injection device that can accurately open a valve when the operation is performed.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a safety valve for a fuel injection device according to the present invention is a safety valve for a diesel injection system provided in a fuel injection device having a pressure accumulating pipe for accumulating fuel supplied to a plurality of cylinders of an internal combustion engine.
A valve body having an internal passage for introducing high-pressure fuel in a pressure accumulating pipe and a seat portion formed in the middle of the internal passage;
A valve body that is accommodated in the valve body and opens or closes the internal passage by being seated or separated from the seat portion;
An elastic member for urging the valve body in the closing direction;
A fuel reservoir that is connected to the internal passage and stores the fuel so that the valve body and the elastic member are always immersed in the fuel;
The fuel reservoir portion is bent in a direction perpendicular to the axial direction of the valve body so that fuel is always stored in the valve body that houses the valve body and the elastic member. together we are, have a rising part formed to face upward,
One end is connected to the inner passage outlet side of the valve body so as to extend in the axial direction of the valve body, and the other end is connected to a right-angled bent portion of the rising portion,
Which is connected to the upper end of the rising section, always closed and straight portion to secure the state in which the fuel is filled in the connecting portion and the rising portion of the lower side in the height difference by at a position higher than the internal passage of the valve body It is characterized by that.
[0006]
[Action]
According to the pressure accumulation type fuel injection device of the present invention, since the movable part of the safety valve provided in the passage communicating with the pressure accumulation chamber of the pressure accumulation device is always immersed in the fuel, the pressure in the pressure accumulation chamber becomes a predetermined value or more. Sometimes, the movable part of the safety valve operates accurately, and the safety valve is operated to prevent excessive pressure in the pressure accumulating chamber from being generated.
In addition, the structure in which the seat from the valve body to the connecting part and the rising part is lower than the straight part connected to the upper end of the rising part is lower than the straight part. The fuel up to the part is always maintained . Therefore, since the operating part of the safety valve is always immersed by fuel, it is prevented that the safety valve does not operate due to rust.
[0007]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
1 to 3 show a first 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 “engine”) 1 is provided with injectors 2 corresponding to a plurality of cylinders, and fuel injection from the injectors 2 into each cylinder is performed by an injection control solenoid valve. 3 is controlled by on / off. The injector 2 is connected to the pressure accumulating chamber 4 of the high pressure accumulating vessel 20 common to each cylinder, and the fuel in the accumulating chamber 4 is transferred from the injector 2 to each cylinder of the engine 1 during the period when the injection control electromagnetic valve 3 is open. Be injected. Since a high predetermined pressure corresponding to the fuel injection pressure needs to be continuously stored in the pressure accumulating chamber 4, the high pressure supply pump 7 is connected via the supply pipe 5 and the discharge valve 16. The high-pressure supply pump 7 pressurizes the fuel sucked from the fuel tank 8 through a known low-pressure supply pump 9 to a high pressure, and controls and maintains the fuel in the pressure accumulating chamber 4 at a high pressure.
[0008]
The electronic control unit ECU 40 that controls this system receives, for example, information on the rotational speed and the load from the engine rotational speed sensor 12 and the load sensor 13, and is determined according to the engine operating state determined from these signals. The ECU 40 outputs a control signal to each electromagnetic valve 3 for injection control so that the optimal 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 7 so that the injection pressure becomes an optimum value according to the rotation speed, the load, and the like. A pressure sensor 14 that detects a common rail pressure is disposed at one end of the high pressure accumulator vessel 20 that communicates with the pressure accumulating chamber 4, and the signal of the pressure sensor 14 is an optimum value that is set in advance according to the rotational speed and load. Thus, the discharge amount of the high-pressure supply pump 7 is controlled.
[0009]
As shown in FIG. 1, a safety valve 15 is provided at the other end communicating with the pressure accumulating chamber 4 of the high pressure accumulating vessel 20. As shown in FIG. 3, the safety valve 15 has a conical seal 18 that is caulked and fixed to the through hole 17 of the valve body 16. An orifice 19 communicates with the bottom of the through hole 17 in the axial direction. A housing 22 is screwed to the flange portion 21 of the valve body 16. The end surface 22 a of the housing 22 is in contact with the bottom surface of the valve body 16 via the gasket 24. A valve body 26 slidable in the axial direction is accommodated in a large-diameter hole 25 formed in the housing 22, and a ball 28 is accommodated between one end face 26 a of the valve body 26 and the seat portion 29. . A compression coil spring 33 is accommodated in the small diameter hole 31 communicating with the large diameter hole 25 formed in the housing 22, and one end portion 33 a of the compression coil spring 33 urges the valve body 26, and the other end portion. 33b is in contact with an annular shim 34 for adjusting the valve opening pressure having a predetermined thickness. The central hole 34a of the annular shim 34 is connected to the pipe 40 on the downstream side of the fuel tank 8 via the through holes 35 and 36 as shown in FIG.
[0010]
Pipe 40, as shown in FIG. 1 comprises a steel pipe or a rubber hose or the like, a connecting portion 41 connected to the through hole 36 of the safety valve 15, a rising part 42 which is bent at a right angle from the connecting portion 41, further a straight portion 43 extending bent from the rising portion 42 so as to be parallel to the connecting portion 41, made of depending portion 44 which is formed so as to hang parallel to the rising portion 42 from the straight portion 43. As shown in FIG. 1, the rising portion 42 is in a state of being filled with fuel. This is because the straight portion 43 is positioned higher than the through hole 36 of the safety valve 15 to ensure that the connecting portion 41 and the rising portion 42 on the side where the fuel is low due to the height difference are always filled.
[0011]
When the fuel pressure in the pressure accumulating chamber 4 of the pressure accumulating container 20 is equal to or lower than the valve opening pressure of the ball 28, the safety valve 15 is seated on the seat portion 29.
In this state, when the fuel pressure in the pressure accumulating chamber 4 rises, the fuel introduced into the through hole 17 through the through hole 39 in the conical seal 18 resists the urging force of the compression coil spring 33 and pushes the ball 28. Open the valve. When the ball 28 and the valve body 26 move to the right in FIG. 3, the fuel flowing through the through hole 19 is introduced into the large diameter hole 25 around the valve body 26, and this high pressure fuel passes through the small diameter hole 23. Through the holes 35 and 36, the pressure is released to the low pressure side at once, and the inside of the pressure accumulating chamber 4 is instantaneously returned to a constant pressure.
[0012]
Next, (1) when the injection pump system is shipped, (2) when the injection pump system is mounted on the internal combustion engine, and (3) during maintenance inspection after the vehicle is shipped.
(1) At the time of shipment of the injection pump system, the injection pump system is shipped with the pressure accumulating vessel 20 and the safety valve 15 attached.
(2) When the injection pump system is mounted on an internal combustion engine, a pipe 40 is provided downstream of the safety valve 15, and the end of the pipe 14 is connected to the fuel tank 8 as shown in FIG. After the injection pump system is mounted on the internal combustion engine, the operating state of the internal combustion engine is tested. At this time, an excessive pressure is applied to the pressure accumulating chamber 4 by the pressurizing means 60 to check that the safety valve 15 operates properly. After confirming that the safety valve 15 operates properly, if the test of the operating state of the internal combustion engine is good, then a vehicle equipped with this internal combustion engine is shipped.
[0013]
(3) During maintenance and inspection after the vehicle is shipped, the operation of the pressure accumulating container 20 and the safety valve 15 is confirmed by removing the pipe 40. At this time, the pipe 40 is removed from the safety valve 15.
Next, a second embodiment of the present invention is shown in FIG.
The pipe 50 connected to the safety valve 15 according to the second embodiment includes an axial portion 51, a hanging portion 52 that hangs downward, a connecting portion 53 bent by approximately 90 ° from the hanging portion 52, and a lower end of the connecting portion 53. And a connecting portion 55 that is bent in the horizontal direction from the upper end of the rising portion 54. The top portion of the rising portion 54 is raised upward relative to the axial direction portion 51, and the inclination angle θ of the rising portion is larger than a predetermined value. This is because the safety valve 15 is always filled with fuel even when the vehicle is tilted because the angle θ is equal to or greater than a predetermined value. The pipe 50 is made of iron piping or a rubber hose.
[0014]
According to the second embodiment, the first embodiment has a rising portion 42 that rises upward from the axial direction portion 41, whereas a hanging portion 52 that hangs downward with respect to the axial direction portion 51 is formed and always at the bottom portion. Take a configuration to store fuel. In this configuration as well, the fuel in the safety valve 15 is always filled with fuel, so that the valve body 26, the spring 33, the ball 28, and the like are prevented from being fixed due to rust. Therefore, when the pressure in the pressure accumulating chamber 4 of the pressure accumulating container 20 becomes excessive pressure, the operation of the safety valve 15 works properly, thereby preventing the fuel from being excessively injected and sticking on the high pressure pump 7 side.
[0015]
【The invention's effect】
According to the pressure accumulation type fuel injection device of the present invention, since the safety valve provided in the passage communicating with the pressure accumulation chamber is always immersed in the fuel, the safety valve is surely opened when the pressure in the pressure accumulation chamber exceeds a predetermined value. In addition to preventing excessive injection from the fuel injection valve, it is possible to prevent sticking of the high-pressure pump and damage to the injector due to exceeding a predetermined pressure.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the main part of a first embodiment of the present invention.
FIG. 2 is a piping diagram showing a fuel injection system of the present invention.
FIG. 3 is a sectional view showing a safety valve according to a first embodiment of the present invention.
FIG. 4 is a schematic diagram showing the main part of a second embodiment of the present invention.
[Explanation of symbols]
4 Pressure accumulation chamber 15 Safety valve 16 Valve body 17 Through hole (internal passage)
19 Orifice (internal passage)
20 High pressure accumulator 22 Housing 25 Large diameter hole (internal passage)
26 Valve body 28 Ball 29 Seat part 31 Small diameter hole (internal passage)
33 Compression coil spring 35 Through hole (internal passage)
36 through hole (internal passage)
40 Pipe 41 Axial part (fuel reservoir)
42 Rising part (fuel reservoir)
50 Pipe 52 Hanging part (fuel reservoir)
53 Piping section (fuel reservoir)
54 Rising part (fuel reservoir)

Claims (2)

In a safety valve for a diesel injection system provided in a fuel injection device having a pressure accumulating pipe for accumulating fuel supplied to a plurality of cylinders of an internal combustion engine,
A valve body having an internal passage for introducing high-pressure fuel in a pressure accumulating pipe and a seat portion formed in the middle of the internal passage;
A valve body that is accommodated in the valve body and opens or closes the internal passage by being seated or separated from the seat portion;
An elastic member for urging the valve body in the closing direction;
A fuel reservoir that is connected to the internal passage and stores the fuel so that the valve body and the elastic member are always immersed in the fuel;
The fuel reservoir portion is bent in a direction perpendicular to the axial direction of the valve body so that fuel is always stored in the valve body that houses the valve body and the elastic member. And has a rising portion formed to face upward,
One end is connected to the inner passage outlet side of the valve body so as to extend in the axial direction of the valve body, and the other end is connected to a right-angled bent portion of the rising portion,
It is connected to the upper end of the rising part, and has a connecting part on the lower side with a difference in height and a straight part that ensures that the rising part is always filled with fuel by being at a position higher than the internal passage of the valve body. A fuel injection device safety valve. In a safety valve for a diesel injection system provided in a fuel injection device having a pressure accumulating pipe for accumulating fuel supplied to a plurality of cylinders of an internal combustion engine,
A valve body having an internal passage for introducing high-pressure fuel in a pressure accumulating pipe and a seat portion formed in the middle of the internal passage;
A valve body that is accommodated in the valve body and opens or closes the internal passage by being seated or separated from the seat portion;
An elastic member for urging the valve body in the closing direction;
A fuel reservoir that is connected to the internal passage and stores the fuel so that the valve body and the elastic member are always immersed in the fuel;
The fuel reservoir portion is bent in a direction perpendicular to the axial direction of the valve body so that fuel is always stored in the valve body that houses the valve body and the elastic member. And has a rising portion formed to face upward,
An axial portion connected to the inner passage outlet side of the valve body so as to extend in the axial direction, a hanging portion hanging downward, and a lower end of the hanging portion connected to the lower portion, bent by 90 ° from the axial direction of the hanging portion A connecting portion,
1. The safety valve for a fuel injection device according to claim 1, wherein the rising portion has a top portion that is connected at one end to the connecting portion and is raised above the axial direction portion .

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