JPH11210593A - Fuel injection device using coaxial flat seat poppet valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device compact and easy to manufacture and assemble. SOLUTION: A fuel injection device 20 has first and second flat seat poppet valves 80, 88 on its center axis, and the respective valves 80, 88 controls fluid pressure acting upon a first end side path 222 and a second end side path 224 of a shutoff valve 84, so as to control fuel injection to an attached engine cylinder. The number of part items and manufacturing mandays are therefore reduced, and space for accommodating a solenoid with a larger diameter can be secured so as to obtain larger solenoid force. In addition, larger space for accommodating other parts such as a connecting instrument for external wiring can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection device, and more particularly to a fuel injection device using two coaxially arranged smooth seat poppet valves.

[0002]

2. Description of the Related Art In a fuel injection engine, a fuel injection device is used, and fuel that is quantitatively adjusted by the fuel injection device is supplied to each engine cylinder for each engine cycle. Conventional fuel injection devices are of the mechanical or hydraulic type. Recently, electronically controlled fuel injection devices have been developed. In a mechanically driven electronically controlled unit injector, fuel is delivered to the injector by a transfer pump. The injection device uses a cam-driven rocker to pressurize the pumped fuel to a high pressure.
It has a plunger operated by an arm. An electric drive mechanism provided outside or inside the injector main body operates to supply fuel to an attached engine cylinder.

[0003] In the structure of a conventional fuel injection device, a high-pressure fuel path is provided outside a central space accommodating a solenoid for driving a valve mechanism. These fuel paths are formed as intersecting drill holes passing close to the outer surface of the injector. After drilling, part of the hole must be closed with a plug. Since these holes and plugs are subjected to extremely high pressure, careful design is required, which complicates and raises the cost.

Further, since the high-pressure path is located outside the solenoid, the solenoid force that can naturally limit the size of the solenoid is limited.

Further, in a conventional type fuel injection device,
Due to the use of the direct-acting check valve, proper operation requires precise position adjustment to align the axes of the upper and lower valve seats. This results in tighter manufacturing and assembly tolerances, further increasing costs.

[0006]

SUMMARY OF THE INVENTION The fuel injector of the present invention has a high pressure fuel path substantially coincident with its central axis.

More specifically, in one embodiment of the present invention, the fuel injection device is provided with an injection device case having a central axis, a plunger hole, and an opening which is in communication with the plunger hole and substantially coincides with the central axis. A plunger path is provided. The central tubular body has a first end and a second end,
A central path is formed between the first end and the second end.
A first valve provided in the valve space surrounds the first end of the central tubular body, and has a position between an open position where the central path communicates with the plunger path and a closed position where the central path communicates with the valve space. Moving. The second end of the central tubular body has an end forming a second valve, the first position of the first end side path and the second end side path of the closing valve communicating with each other, and the first end side path is It moves between the second position blocked from the second end side path. An actuator is provided to move the first and second valves.

Preferably, the first and second valves are flat seat poppet valves. Further, when the second valve comes to the second position, it is desirable that the second end side path of the closing valve communicates with the drain path.

Further, as a preferred mode, it is desirable that the actuator is a solenoid or other electric actuator having first and second cores connected to the first and second valves, respectively.

Preferably, the first valve is biased by the first valve spring in the direction of the open position, and the second valve is biased by the second valve spring in the direction of the first position. The first valve spring generates a first spring force, and the second valve spring generates a second spring force larger than the first spring force.

In another aspect of the present invention, a fuel injection device includes:
An injector case having a central axis and a central path substantially aligned with the central axis and directing fuel from the first end to the second end. A first flat seat poppet valve surrounds the first end of the central path. A second flat seat poppet valve is formed in a portion surrounding the second end of the central path. An actuator is provided for moving the first valve and the second flat seat poppet valve.

In yet another aspect of the invention, a fuel injector has an injector case having a central axis and a plunger path substantially coincident with the central axis. The central tubular body has a central fuel path substantially aligned with the central axis and directing fuel from the first end to the second end. A first flat sheet provided in the valve space and surrounding a first end of the central tubular body;
When the poppet valve moves between the open and closed positions and comes to the open position, the valve space communicates with the plunger path and the center path. When the first flat seat poppet valve is in the closed position, the central path communicates with the plunger path and is isolated from the valve space. A first valve spring biases the first flat seat poppet valve toward the open position. In addition, the first of the closing valve
An end path and a second end path are respectively connected to the first end and the second end of the closure valve assembly. A second end of the central tubular body includes a second end that moves between a first position and a second position.
A portion forming a flat seat poppet valve is included, and when the second flat seat poppet valve is at the first position, the central path is the first end path and the second end path of the closing valve. Communicate. When the second flat seat poppet valve is at the second position, the center path communicates with the first end path, and the second end path communicates with the drain path and is isolated from the center path.
A second valve spring generates a second spring force that urges the second flat seat poppet valve in the direction of the first position, the second spring force being the first spring force.
This value is larger than the spring force. A solenoid is provided having a solenoid coil and a first iron core and a second iron core respectively connected to the first and second flat seat poppet valves, wherein the solenoid coil is provided with a first and a second current waveform portion to provide a first Move the first and second flat sheet poppet valves in sequence.

According to the present invention, the problem of adjusting the position of the seat surface is eliminated because no cross holes or plugs receiving high pressure are required. The number of parts and the number of manufacturing steps are reduced, a space for accommodating a larger-diameter solenoid is secured, and a larger solenoid force is obtained. In addition, more space is provided for accommodating other components, such as external wiring connections.

[0014]

FIG. 1 shows a direct injection diesel engine.
1 shows a part of a fuel system 10 applied to a cycle reciprocating engine. However, the invention is also applicable to other types of engines having at least one fuel chamber or cylinder, such as a rotary engine or an improved cycle engine. The engine has at least one cylinder head, each head having one or a plurality of separate mounting holes for mounting the injection device 20 of the present invention.

The fuel system 10 further includes an injection device 20
A fuel supply device 22 for supplying fuel to the fuel injection device, a fuel pressurizing device 24 for pressurizing the fuel with the injection device 20, and a control device 26 for electronically controlling each injection device 20 are provided.

The fuel supply device 22 includes a fuel tank 28, a fuel supply path 30 that connects the fuel tank and the injection device 20,
A relatively low head fuel transfer pump 32, one or more fuel filters 34, and the injector 20 and fuel tank 28;
Is desirably provided with a fuel drain path 36 communicating with the fuel cell. If desired, a fuel system in communication with the fuel injector 20 and one or both of the paths 30 and 36 may be provided at the top of the engine.

The fuel pressurizing device 24 may be mechanically operated or hydraulically operated. In the present embodiment, the tappet / plunger assembly 50 attached to the injection device 20 includes:
It is mechanically indirectly or directly driven by a cam surface 52 of an engine driven cam shaft 54. The cam surface 52 drives the rocker arm assembly 64 which swings, thereby causing the plunger assembly 64 to reciprocate. A push rod (not shown) may be interposed between the cam surface 52 and the rocker arm assembly 64.

The electronic control unit 26 includes (1) fuel injection timing, (2) the total fuel injection amount during the injection cycle,
(3) fuel injection pressure, (4) number of independent injection periods during the injection cycle, (5) time interval between injection periods, and (6).
Preferably, an electronic control module (ECM) 66 for controlling the amount of fuel injected during each injection period during each injection cycle is provided.

Each of the injectors 20 converts the fuel to a high pressure (for example,
A device that pressurizes at 207 MPa (30,000 p.si) and injects pressurized fuel into an attached cylinder
It is desirable that the unit type injection device is built in one housing. In the present embodiment, the unit type injection device 20
However, the separated fuel injection device may be a modular injection device incorporating a fuel pressurizing device.

Next, as shown in FIGS. 2 and 3, the injection device 20 includes a case 74, a nozzle portion 76, an electric actuator 78, a relief valve 80, a relief valve spring 81, and a plunger disposed in a plunger hole 83. 82, shut-off valve 84,
A closing valve spring 86 surrounding a closing valve piston 87 which forms a closing valve assembly together with the closing valve 84, a direct-acting check (DOC)
A valve 88 and a DOC spring 90 are provided. The relief valve spring 81 generates a first spring force when compressed, and the DOC spring 9
It is desirable that 0 generates a second spring force larger than the first spring force during compression.

As shown in particular in FIG. 3, the electric actuator 78 includes a solenoid 100 for controlling the valves 80 and 88.
It is desirable to configure with. Actuator 7 if necessary
8 can be composed of other types of devices. The solenoid 100 includes a stator 102 having a space 104 for housing a solenoid coil. Further solenoid 10
0 has an iron core assembly including a first iron core 108 and a second iron core 110, and each iron core is disposed on both sides of an annular center spacer member 112 made of a non-magnetic (high reactance) material. Have been. Spacer member 112
May be separated from other members, and the core 10
8, 110, or may be fixed to the coil bobbin 116 held by the stator 102. The first core 108 and the second core 110 surround the axially movable central tubular body 120, like the first valve 80 and the central spacer member 112.

The solenoid stator 102 includes first and second solenoids.
The outer portions 126, 128 and the central portion 130 form a C-shaped cross section. Surface 132 of outer portion 128 and iron core 10
8 form a first air gap, and a second air gap is formed between the opposing surface 138 of the outer portion 126 and the surface 140 of the core 110. A washer 142 in contact with the first iron core 108 is in contact with the relief valve 80. Route 1
44 communicates with a valve space 146 containing the relief valve 80;
Further, it communicates with the space 148. The valve space 146 communicates with a fuel supply path (not shown). Drain route 15
0 communicates with the drain through another path (not shown).

Washer 160 in contact with second iron core 110
Abuts a retaining ring 162 mounted in a groove in the central tubular body 120. The washer 164 in contact with the holding ring 162 is urged by the DOC spring 90.
The central tubular member 120 has an end 17 that constitutes the DOC valve 88.
It has 0. The end 170 has a conical sealing surface 1 that matches the conical seating surface 174 formed on the valve body member 154.
72 are formed. (The outer diameter of the end portion 170 of the central tubular member 120 having a center hole is slightly larger than the outer diameter of the portion above the seat 174.) The end portion 170 has a flat seat surface 181 of another valve box member 182. Has a conical lower poppet surface 178 defining an outer peripheral knife edge 180 opposite the upper surface. The poppet face 178 and the flat seat face 181 constitute a second valve.

FIG. 4 shows the current waveform portions 192, 194 supplied by the drive circuit 196 to the solenoid coil 106 during the injection period during which fuel injection occurs. Time t
= T ₀ and t = t ₅ , the first current waveform portion 192 is supplied, and the second current waveform portion 194 is supplied after t = t ₅ . Between times t = t ₀ and t = t _2, a first draw current is supplied to the solenoid coil 106 and a slightly lower level of the first holding current is applied at subsequent times t = t ₂ and t = t ₅ . Supplied in between. A second draw current, typically higher than the first draw current, is supplied between times t = t ₅ and t = t ₈ ,
The second holding currents higher than the holding current are time t = t ₈ and t = t ₉
Supplied during.

More specifically, before the start of the injection period, since the solenoid coil is not excited, the relief valve spring 8
By 1 (generating a first spring force), the knife edge 197 on the outer periphery of the conical sealing surface 198 of the poppet is separated from the flat seating surface 200 and the relief valve 80 is open. At this time, the central tubular body 120 is pushed up by the DOC valve spring 90 (which generates a second spring force larger than the first spring force), and the knife edge 180 on the outer periphery of the seal surface 178 is separated from the flat seat surface 181. , A conical seal surface 172 is in contact with the conical seat surface 174. In this state, fuel flows from the inlet passage (not shown) to the valve space 14.
6, the plunger path 208 (FIG. 2), the paths 210 and 212 in the plunger 82, and the plunger 8
It flows out to the drain path through the annular groove 214 surrounding the 2.
At the same time, fuel is exhausted through the passage 144, the recess 148 and the space around the central tubular body 120. Thereafter, when the cam surface pushes down the plunger 82 of the injection device 20 and the passages 210 and 212 in the plunger 82 are cut off from the annular groove 214, the fuel is pressurized. At this time, the drive circuit 196 supplies the first current waveform portion 192 to the solenoid coil 106. The level of the drawn current and the holding current in the current waveform portion 192 and the strength of the spring force of the valve springs 81 and 90 are such that the force generated in the first iron core 108 exceeds the first spring force generated by the spring 81. 2 iron core 110
Is selected so as not to exceed the second spring force generated by the spring 90. Therefore, the first iron core 10
8 pushes up the washer 142 to close the relief valve 80. At this time, the outer knife edge 197 comes into contact with the flat sheet surface 200, and the plunger path 208 and the valve space 1
Block between 46. At the same time, since the spring force of the valve spring 90 is greater than the force generated in the second iron core 110, the above-described condition is maintained while the DOC valve 88 is open. Therefore, the fuel pressurized by the lowering of the plunger 82 passes through the central path 220 of the central tubular body 120,
The fuel pressure sent to the first end path 222 and the second end path 224 of the closing valve communicating with the lower end and the upper end of the closing valve assembly, respectively, and acting on the upper and lower ends of the closing valve assembly is substantially increased. Balanced. At this time, the closing valve remains closed by the spring 86.

Thereafter, the drive circuit 196 supplies a second current waveform portion 194 to the solenoid coil 106. When the force generated in the second core 110 increases due to the increase in the current level and exceeds the second spring force, the second core 110 descends. This downward movement is transmitted to the valve 88 via the drive washer 160 and the retaining ring 162, which lowers the outer knife edge 180 against the flat sheet surface 181. The conical sealing surface 172 is
Move away from 4. This movement isolates the second end path 224 of the shutoff valve from the pressurized fuel in the center path 220 and the second end path 224 of the shutoff valve connects the drain path 150
(The connection path from the path 150 to the drain is not shown). When the pressure balance acting on the upper and lower ends of the closing valve assembly is lost in this way, the closing valve rises and fuel is injected into the cylinder.

When terminating the injection, the current supplied to the solenoid coil 106 is reduced to the level of the first current waveform portion 192 shown in FIG. If necessary, reduce the current supplied to solenoid coil 106 to zero or first
It may be reduced to any level below the holding level.
In any case, first, the DOC valve 88 rises, and the first end side path 224 and the second end side path 222 of the closing valve communicate again. When the pressures at the upper and lower ends of the closing valve are thus balanced, the closing valve 84 is closed by the closing valve spring 86. At this time, the current value is reduced to zero or lower than the first holding level (if not reduced). When the DOC valve 88 is pushed up by the DOC valve spring 90, the relief valve 80 opens the relief valve 80, regardless of whether the supply current drops rapidly to the first holding level or below.

If necessary, three or more current waveform portions are supplied to the solenoid coil to move one or more cores to an arbitrary number of positions (not limited to two positions),
One or more valves or other moving members can be driven.

In addition, by providing appropriate current waveform portions to the solenoid coil 106, multiple independent injections can be performed during an injection cycle. For example,
The first and second current waveform portions can be supplied to perform a first preliminary injection. Immediately thereafter, the second main injection can be performed by reducing the current value to the first holding level and increasing the current value again to the second pull-in level and the second holding level. When performing the preliminary and main injection, first, the current waveform portions 192 and 194 are applied to the solenoid coil 106.
And then perform pre-injection, then the solenoid coil 1
At 06, the main injection can be performed by repeatedly supplying the current waveform portions 192 and 194. The duration of the pre-injection and the main injection (ie, the injection amount during each injection period) is determined by the current waveform portion
It depends on the duration of the second holding portion 94. Of course, the current waveform shown in FIG. 4 can be changed as needed to obtain appropriate injection response characteristics and other desirable characteristics.

As is apparent from the above description, the central passage 220 substantially coincides with the central axis of the injector 20, and the first end and the second end thereof are the plunger passage 208 and the shut-off valve, respectively. Of the first end side path 222 of FIG. Since the fuel flows through the center of the injector, there is no need for cross holes or plugs where high pressure acts. Furthermore, since the relief valve 80 and the DOC valve 88 are flat seat poppet valves arranged coaxially, there is no need to adjust the position for aligning the axis of the seal surface with the axis of the seat surface. Furthermore,
The larger diameter of the solenoid coil 100 allows more force to be generated on the iron core, thereby improving the functionality of the injector. Since the fuel path does not pass outside the solenoid, a space for accommodating other components such as a wiring connection device for connecting the solenoid and the drive circuit 196 is increased.

The valve used in the fuel injection device of the present invention has a flat seat surface, and the flat seat surface requires a larger sealing pressure than a valve having a conical seat surface, and has a conical seat surface. The larger mass of the valve compared to the valve results in a slightly slower response than the conventional DOC valve 88, but these disadvantages are fully compensated by the above advantages.

From the above description, it is considered that various improvements and modifications of the present invention are easy for those skilled in the art. Therefore,
The above description should be interpreted to disclose the best embodiments of the present invention to those skilled in the art. Changes may be made in details of structure and / or operation without departing from the spirit of the invention, but all such modifications that fall within the scope of the appended claims are assured of exclusive implementation. ing.

[Brief description of the drawings]

FIG. 1 is a side view of a fuel injection device according to the present invention, showing a block diagram of a camshaft and a rocker arm, as well as a transfer pump and an electronic control module of the fuel injection device.

FIG. 2 is a partial cross-sectional view of the fuel injection device of FIG.

3 is an enlarged partial cross-sectional view of the fuel injection device of FIG. 2, showing the high pressure relief valve and the DOC valve in detail.

FIG. 4 is a waveform diagram of a current waveform supplied to the solenoid coil shown in FIGS. 2 and 3;

[Explanation of symbols]

 Reference Signs List 20 fuel injection device 78 actuator 80 first flat seat poppet valve 84 closing valve 88 second flat seat poppet valve 178 first end side path 224 ... Second end side route

Continuation of the front page (71) Applicant 598141143 Lucas Industries Public Limited Company UK B 90 4L A.E. Coldren United States 61739-9550 Illinois Fairbury Lakeview Drive 40 (72) Inventor Marvin P. Schneider United States 61611-1480 Illinois East Peoria High Oak Drive 305 (72) Inventor Glen F. Falk United States 61615 Illinois Peoria Talisman Terrace 6230 (72) Inventor James Jay. Stracher United States 61764-1506 Illinois Pontiac Apache Drive 1302

Claims (16)

[Claims] 1. A case of an injection device having a central axis, a plunger hole, a plunger passage communicating with the plunger hole and having an opening at a position substantially coincident with the central axis, a first end communicating with the opening. A central tubular body having a second end, and a central path between the first end and the second end, provided in the valve space, surrounding the first end of the central tubular body,
An open position where the center path communicates with the plunger path;
A first valve movable between a closed position in which the center path communicates with the valve space, a first end path and a second end path of the stop valve, and a second end of the center tubular body, A first position where the first end side path and the second end side path communicate with each other;
A fuel injection device comprising: a second valve movable between an end-side path and a second position where the second end-side path is isolated; and an actuator that moves the first valve and the second valve. 2. The fuel injection device according to claim 1, wherein said first and second valves are flat seat poppet valves. 3. The fuel injection device according to claim 1, wherein the second end side path communicates with the drain path when the second valve comes to the second position. 4. The fuel injection device according to claim 1, wherein said actuator comprises a solenoid. 5. The fuel injection device according to claim 1, wherein the solenoid has a first iron core and a second iron core connected to the first valve and the second valve, respectively. 6. The first valve is urged in a direction of an open position by a first valve spring, and the second valve is urged by a second valve spring to a first position.
The fuel injection device according to claim 1, wherein the fuel injection device is biased in a position direction. 7. The first valve spring generates a first spring force,
2. The fuel injection device according to claim 1, wherein the second valve spring generates a second spring force larger than the first spring force. 8. An injector case having a central axis, a central path for guiding fuel from the first end to the second end, substantially coincident with the central axis, and a first end of the central path. A fuel injector comprising: a surrounding first flat seat poppet valve; a second flat seat poppet valve surrounding a second end of the center path; and an actuator for moving the first and second poppet valves. 9. The fuel injection device according to claim 8, wherein said first and second flat seat poppet valves are movable between two positions. 10. The first flat seat poppet valve according to claim 1,
The fuel injection device according to claim 9, wherein the fuel injection device moves between an open position provided in the valve space and communicating the center path with the valve space and a closed position communicating the center path with the plunger path. 11. The valve according to claim 11, wherein the second flat seat poppet valve comprises:
A first position where the center path communicates with the first end path and the second end path of the closing valve; and a second end path that is separated from the first end path and the second end path as a drain path. The fuel injection device according to claim 10, wherein the fuel injection device moves between the first position and the second position. 12. The fuel injection device according to claim 8, wherein said actuator is a solenoid. 13. The method according to claim 13, wherein each of the solenoids comprises the first
The fuel injection device according to claim 12, further comprising a first core and a second core connected to the valve and the second valve. 14. The first flat seat poppet valve is urged in a direction of an open position by a first valve spring, and the second flat seat poppet valve is
14. The fuel injector according to claim 13, wherein the flat seat poppet valve is biased in the direction of the first position by a second valve spring. 15. The fuel injection device according to claim 14, wherein the first valve spring generates a first spring force, and the second valve spring generates a second spring force larger than the first spring force. 16. An injector case having a central axis, a plunger path substantially coincident with the central axis, substantially coincident with the central axis for directing fuel from a first end to a second end. A central tubular body having a central path, disposed in the valve space, surrounding the first end of the central tubular body,
When the valve space moves between the open position and the closed position and comes to the open position, the valve space communicates with the plunger path and the center path, and when the valve space comes to the closed position, the center path communicates with the plunger path. A first flat seat poppet valve isolated from a space, a first valve spring for biasing the first flat seat poppet valve in a direction of an open position, a closing valve assembly, first and second of the closing valve assembly A first end-side path and a second end-side path of a closing valve connected to the two ends, a drain path, surrounding the second end of the central tubular body, and moving between a first position and a second position; When reaching the first position, the center path communicates with the first end side path and the second end side path, and when reaching the second position, the center path communicates with the first end side path; A second flat sheet in which the second end-side path communicates with the drain path and is isolated from the central path; A second valve spring for urging the second flat seat poppet valve in the direction of the first position to generate a second spring force greater than the first spring force, and a solenoid coil; A first connected to the first and second flat sheet poppet valves;
A fuel injection having a core and a second core, wherein a solenoid coil is energized by the first and second current waveform portions, thereby moving the first and second flat seat poppet valves. apparatus.