JP2000002166A - Fuel injection device, adapter plate for use for this fuel injection device and manufacture of fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a necessary passage at a low cost by making a fuel injection device have a constitution that the device is formed so as to include a structure partitioning a duct in which one of upper and lower surfaces of an adapter plate arranged between a nozzle holder and a nozzle main body is limited. SOLUTION: A lower surface of an adapter plate 26 and an upper surface are abutted on an upper surface of a spacer part piece 24 and a lower end face of a valve housing 32, respectively. When a valve member 36 is lifted from a seat at the time of starting injection, fuel escapes to a low pressure exhaust container from a control chamber 28 through a recessed portion 72 of the lower surface of the adapter plate 26, a recessed portion 54 of the upper surface of the communicated adapter plate 26 and a bore hole 40, downward force acting on a valve needle 14 is reduced and fuel injection is performed. Fuel amount which can be flowed into a chamber 22 is limited at the recessed portion of the lower surface of the adapter plate 26 and a recessed portion partitioned by a wall and fuel pressure within the chamber 22 is made lower than a level before an injection is started during an injection period. When the injection is terminated, fuel flow pressurizes the bore hole 40, the recessed portion 54 and the recessed portion 72, pressure acting on the valve needle 14 exposed to fuel pressure within the recessed portion 72 is increased and injection is quickly terminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for use in supplying fuel under pressure to a cylinder of an internal combustion engine, an adapter plate used for the fuel injection device, and a method of manufacturing the fuel injection device. About.

[0002]

BACKGROUND OF THE INVENTION In fuel injectors of the type intended for use in common rail fuel systems, a number of restricted flow paths are directed to holes through which the valve tension can slide and the operation of the injector. In order to control, it must be provided to allow the supply of fuel to a control valve that controls the fuel pressure in the control chamber. It is known to provide such restricted channels by forming appropriate holes or perforations in the nozzle body, spacer piece and valve housing of the injector. However, providing such perforations or holes requires a high level of precision. As a result, appropriate perforations and holes must be machined into each component to form the required passages during manufacture, and the passages must be ground to the correct dimensions. Each component is then tested and, if necessary, polished again. It will be appreciated that such machining steps are time consuming and expensive.

[0003]

It is also desirable to provide a filter in the injector to prevent dirt particles from flowing to the control valve and impairing or damaging its operation. The provision of such a filter increases the number of components present in the injector, thus increasing the cost of the injector and increasing the complexity of the assembly process.

[0004] It is an object of the present invention to manufacture a fuel injection device relatively easily and at relatively low cost by using an adapter plate.

[0005]

According to the present invention, there is provided a nozzle body, a nozzle holder, and an adapter plate disposed between the nozzle holder and the nozzle body. A fuel injection device is provided, at least one of which is configured to include a structure defining a restricted flow path.

If the injector is used in a conventional rail type, the structure is such that an opening through which fuel can flow in a controlled amount toward the bore of the nozzle body, a restriction through which fuel can flow into the control chamber in a limited amount. The defined flow path and the flow path connecting the control chamber to the control valve are advantageously defined. The adapter plate advantageously further includes a structure defining a filter arranged to remove dirt particles from the fuel flow to the control chamber and control valve.

The use of such adapter plates is advantageous because the manufacture of the fuel injector can be achieved relatively easily and at relatively low cost. Structures manufactured using micromachining techniques are precisely positioned, thus allowing mass production of substantially identical components with high precision without requiring significant post-production processing.

[0008] The present invention further relates to a method of manufacturing an injection device, comprising micromachining at least one of the upper and lower surfaces of an adapter plate to produce a structure defining a restricted flow path in use. The process of micromachining the adapter plate can use, for example, photolithography, X-ray lithography, electroforming and laser micromachining techniques. The use of such a technique allows the manufacture of the structure of the adapter plate in a precisely controlled arrangement at a relatively low cost.

It is understood that the present invention is applicable to common rail fuel injector types other than those described above, as well as to other types of fuel injectors.

The invention will be described below, by way of example, with reference to the accompanying drawings, in which:

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The injection device partially shown in FIG.
Nozzle body 10 in which a blind hole 12 is formed, through which the nozzle can slide.
And the end of the valve needle 14 is adjacent to the blind end of the hole 12 to control the supply of fuel through the seat from the hole 12 to one or more outlet openings formed in the nozzle body 10. Engageable with the defined seat. The bore 12 is shaped to include an annular passage 16 of enlarged diameter.
Is connected via a supply passage 18 to a fuel source under high pressure, for example a common rail which is loaded with fuel at high pressure by a suitable pump. As shown in FIG.
Is shaped to include an area that engages the outer surface of the valve needle 14 to guide the valve needle for sliding movement. And is formed to include a groove 20 that allows flow to an annular chamber 22 defined between the diametrical portion. The valve needle 14 includes an angled thrust surface that is exposed to fuel pressure in the bore 12, and the application of high pressure fuel to the bore 12, which applies a force to the valve needle 14, pushes the valve needle 14 away from the seat. Act on.

The upper end of the nozzle body 10 has a through hole arranged in line with the hole 12 of the nozzle body 10 and a spacer piece 24 including a perforation forming a part of the supply passage 18. Is in contact with The upper end of the valve needle 14 extends into the through hole of the spacer piece 24.

The adapter plate 26 is in contact with the upper surface of the spacer piece 24. The adapter plate 26 closes the through hole of the spacer piece 24. The through hole of the spacer piece 24 and the upper part of the valve needle 14 are both in the control chamber. The fuel pressure in the control chamber that defines 28 and acts against the valve needle 14 exerts a force on the valve needle 14 and urges the valve needle 14 toward the seat. A helical compression spring 30 is located in the control chamber and applies an additional force to the valve needle 14 that pushes the valve needle 14 toward its seat.

The upper surface of the adapter plate 26 has a valve housing 32
Abuts against the lower end face of the supply passage.
The perforation and control valve member 36 forming the part includes a through hole 34 slidable therein. Control valve member 36
Is connected to the valve housing 3
2 includes an area of reduced diameter defining an annular chamber 38 communicating with the lower end surface of the second. The valve member 36 further includes an enlarged diameter region capable of engaging a seat defined around an end portion of the through hole 34, wherein engagement of the valve portion 36 with the seat includes:
It controls the communication between the perforations 40 and the chamber 42 in communication with the low-pressure discharge vessel via suitable perforations (not shown) and in use.

The valve member 36 is biased into engagement with a seat by a spring 44 disposed in a hole formed in a nozzle holder 46 abutting on the upper surface of the valve housing 32, and the nozzle holder 46 further houses an electromagnetic actuator. are doing. The actuator is such that, when energized, the armature 48 supported by the valve member 36 is pulled toward the actuator against the action of the spring 44 such that the armature 48 lifts the valve member 36 away from its seat. Are located in When the actuator is de-energized, the valve member 36 returns into engagement with the seat under the action of the spring 44.

The adapter plate 26 is made of a relatively thin plate,
The upper and lower surfaces are photolithographic, X-shaped to form a pattern of recesses on these upper and lower surfaces.
Machined using micromachining techniques such as line lithography, electroforming or laser micromachining. The recess formed in the upper surface of the adapter plate 26 is the adapter plate 2
6, and the recess formed in the lower surface also has an opening in the adapter plate when the upper surface recess and the lower surface recess are highly aligned. It extends approximately halfway through the adapter plate 26 so as to form the adapter plate 26 completely therethrough. Alternatively, if the passages are required to extend completely through the adapter plate 26, they can be machined from only one side of the plate, if necessary.

FIGS. 2 and 4 show patterns of recesses formed on the upper surface of the adapter plate 26. FIG. As shown in FIG. 2, a recess 50 is formed, and the recess 50
There is provided communication between the lower end of 4 and an additional through hole 52 connecting the lower surface of valve housing 32 and chamber 42.

The upper surface of the adapter plate 26 further defines a recess 54 extending from the central portion of the adapter plate 26 to a region in use located on the lower surface of the valve housing 32 adjacent the end of the bore 40 in use. It has the same structure.
The recess 54 communicates with the recess 56 via a channel 58 formed in the upper surface of the smaller dimension adapter plate 26, thus forming a restricted flow path between the recesses 54,56. The recess 56 further communicates via a channel 60 of small size with a recess 62 which is arranged to extend above a part of the control chamber 28. As shown in FIGS. 2 and 4, the structure defining the recess 62 includes a series of finger portions 64 extending across a portion of the width of the recess 62 and is applied by a spring 30 to the valve housing 32. It acts to transmit the required load.

Within the recess 56, the structure formed on the upper surface of the adapter plate 26 includes a relatively small diameter annular wall 66 that is aligned with the axis of a portion of the supply passage extending through the valve housing 32. To define. As best seen in FIG. 4, surrounding wall 66 is a plurality of closely spaced filters defining a filter that restricts the flow of dirt particles from supply passage 18 toward control chamber 28 and control valve. Is the wall 68 on which is placed.

FIG. 3 shows a structure formed below the adapter plate 26. As shown in FIG.
A small diameter recess 70 is formed in the lower portion of the adapter plate 26 in alignment with the recess defined by the
The recess and recess 70 communicate with each other to define a limited diameter portion of the supply passage 18.
The central portion of the adapter plate 26 further comprises a recess 72 communicating with a recess 54 formed in the upper surface of the adapter plate 26, thus providing a control chamber 28 communicating with a control valve and a perforation 4.
A flow path is provided between 0 and 0. A series of recesses 74 are also formed in the lower surface of the adapter plate 26, and the recesses 74 are formed in the upper surface of the adapter plate 26 to form a series of flow paths between the recess 62 and the control chamber 28. Communicates with the portion of the recess 62 formed.

As shown in FIGS. 2 and 3, the adapter plate 26 includes an area that engages a dowel pin 76 used to align the valve housing 32 and the spacer piece 24 in use. And the dowel pin 76 is attached to the adapter plate 26 against the rest of the injector.
Place it exactly. The overall shape of the adapter plate 26 can be selected such that the clamping force applied to the adapter plate by the cap nut forms a good seal around the various fuel flow paths and channels, thus reducing leakage.

Although not shown in the drawings, the nozzle body 10, spacer piece 24, adapter plate 26 and valve housing 32 are defined in use between a wide diameter area and a narrow diameter area of the nozzle body 10. It is secured to the nozzle holder 46 by a threaded cap nut that engages the shoulder provided and is in threaded engagement with a portion of the nozzle holder 46.

In use, high pressure fuel is supplied to supply passage 18 from a common rail that is filled with fuel at a suitably high pressure by a suitable fuel source, for example a suitable pump. It will be appreciated that when the control valve actuator is de-energized, the valve member 36 is biased into engagement with its seat by the spring 44 and the fuel pressure in the control chamber 28 is substantially equal to the fuel pressure in the supply line 18. Upper equal. Similarly, the fuel pressure acting on the angled thrust surface of the valve needle 14
8 is substantially equal to the fuel pressure in and is therefore relatively high. The difference in effective area exposed to the fuel under pressure and to the action of the spring 30 ensures that the valve needle 14 engages its seat, and thus no fuel is supplied through the outlet opening of the injector. .

To begin the injection, the actuator is energized and the valve member 36 is lifted from its seat, thus fuel is removed from the control chamber 28 into the recesses 72, 54 and the perforations 4.
Allows escape through 0 to chamber 40 communicating with the low pressure discharge vessel. Such fuel flow reduces the fuel pressure applied to the information end of the needle 14, thus reducing the downward force acting on the needle 14 pushing the needle 14 toward its seat. The decrease in fuel pressure in the control chamber 28 is controlled by the valve needle 14.
Has reached a point where it can rise away from its seat, thus allowing fuel injection. Movement of the valve needle 14 and injection of fuel through the outlet opening reduces fuel pressure in the chamber 22. Recess 77
And the limitations defined by the recesses defined by walls 66 limit the amount of fuel that can flow into chamber 22, so it is understood that throughout the injection, the fuel pressure in chamber 22 will Before starting, it drops to a level lower than the level present in the chamber 22.

Throughout the injection, fuel can flow in a limited amount through the channel 58 so that a small amount of fuel escapes from the supply line 18 to the low pressure discharge vessel. The dimensions of the channel 58 are chosen to ensure that the amount of fuel wasted in this manner is relatively small. A small amount of fuel also flows through channel 60 into recess 62 and control chamber 28. If the movement of the valve needle 14 is sufficient to cause its end face to engage the lower surface of the adapter plate 26, then the flow of fuel from the chamber 28 to the low pressure discharge vessel will cause the recess 72 to It is blocked because it is closed by the upper surface. The flow of fuel to the control chamber 28 therefore increases the fuel pressure present in the control chamber 28. However, because the area of the valve needle 14 exposed to fuel pressure in the control chamber 28 at this time is relatively small, the additional downward force applied to the valve needle 14 is not sufficient to cause movement of the valve needle 14. It is.

To end the injection, the actuator is deenergized and the valve member 36 returns to engagement with the seat by the action of the spring 44. Such movement of valve member 36 terminates the flow of fuel to the discharge vessel, and the continuous flow of fuel through channel 58 pressurizes perforations 40, recesses 54 and recesses 72. The pressure acting on the portion of the valve needle 14 that is exposed to the fuel pressure in the recess 72 therefore increases, increasing the magnitude of the downward force applied to the valve needle 14 and causing the valve needle 14 to A point which can move towards and in engagement with this seat is achieved.

After the end of the injection, the fuel cannot escape from the chamber 22, so that the pressure in the part of the supply passage 18 downstream of the restriction defined by the recess 70 and the recess defined by the wall 66 Increases substantially upstream of the limit. The injector then prepares for the start of the next injection cycle.

It will be appreciated that the presence of a restriction in the supply passage 18 along with an arrangement that allows for different portions of the upper surface of the valve needle 14 to be exposed to different pressures throughout the injection will result in a rapid injection. The end is tolerated.

The provision of the adapter plate 26 makes it possible to provide predetermined passages to allow operation of the injector in a manner which is relatively simple and relatively inexpensive to manufacture. As mentioned above, the adapter plate 26 uses appropriate micromachining techniques that are low cost and allow the precise placement of the structures required to allow communication between the various parts of the injector. Machined.

FIGS. 5 and 6 show a modification of the arrangement shown in FIGS. In the arrangements of FIGS. 5 and 6, the perforations formed in the valve housing 32 and the spacer piece 24 which together form part of the supply passage 18 are:
The ends provided opposite each other are angled and oriented so that they are not aligned. Passage 7
8 is formed in the adapter plate 26, and the passage 78 communicates with a recess 80 formed on the upper surface of the adapter plate 26 to form a flow path completely penetrating the adapter plate 26. It is shaped to allow communication between the perforations forming the supply passages 18 upstream and downstream of the adapter plate 26. Such an arrangement allows the shape of the supply passage 18 to be shaped to achieve multiple flow characteristics of the supply of fuel to the chamber 22. Except as described above, the embodiment shown in FIGS. 5 and 6 is substantially the same as the embodiment described in connection with FIGS.

In both arrangements described above, the adapter plate 2
The recesses and channels defining the upper and lower surfaces of 6 can be shaped to optimize the flow characteristics through the respective channels and recesses. For example, the structure defining the recess 54 is shaped to allow fuel to flow relatively slowly through the recess 54 when opening the control valve, thus providing relatively accurate control of the momentum of the valve needle 14. And allows fuel to flow in the reverse direction at a relatively high rate, thus allowing precise control of the timing of the end of injection. Other structural shapes can be selected as well.

The walls 66, which together define the filter, are shaped such that the fuel flow channels defined therebetween provide a venturi-type portion such that the flow resistance formed by the filter is minimized. To be oriented.

[0033]

As described above, the present invention provides a nozzle body,
A nozzle holder, and an adapter plate disposed between the nozzle holder and the nozzle body, wherein at least one of an upper surface and a lower surface of the adapter plate is formed to include a structure defining a restricted flow path. With this configuration, it is possible to provide a fuel injection device that can be manufactured relatively easily and at relatively low cost by using an adapter plate.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of a fuel injection device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along lines 3-3 in FIG. 1;

FIG. 4 is an enlarged view of a part of FIG. 2;

FIG. 5 is a similar view of FIG. 2 showing an alternative embodiment.

FIG. 6 is a sectional view taken along lines 6-6 in FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 nozzle body 14 valve needle 26 adapter plate 46 nozzle holder 50 recess 54 recess 56 recess 62 recess 68 filter 70 recess 72 recess 74 recess

Claims (9)

[Claims] A nozzle body (10), a nozzle holder (4)
6) and an adapter plate (26) disposed between the nozzle holder (46) and the nozzle body (10), and at least one of the upper surface and the lower surface of the adapter plate (26) is restricted. A fuel injection device shaped to include a structure defining a flow path. 2. The structure according to claim 1, wherein said structure is a recess (50, 54, 56, 6).
2. The fuel injection device according to claim 1, wherein (2, 70, 72, 74) is defined. 3. The size of said structure is such that said adapter plate (2
6) to define a passage extending through the adapter plate (26) when the recess formed in the upper surface of 6) is aligned with the recess formed in the lower surface. 3. The fuel injection device according to claim 2, wherein the fuel injection devices are open to each other. 4. The adapter plate has an opening through which fuel can flow in a controlled amount toward a hole in the nozzle body (10), a restriction allowing fuel to flow into the control chamber in a limited amount. A flow path, and a flow path connecting the control chamber to a control valve is defined.
4. The fuel injection device according to claim 3. 5. The method according to claim 1, wherein the adapter plate structure defines a filter arranged to remove dirt particles from the fuel stream. Fuel injection device. 6. An adapter plate suitable for use in a fuel injection device of the type according to claim 1. Description: 7. Injection apparatus comprising, in use, micromachining at least one of the upper and lower surfaces of an adapter plate (26) to produce a structure defining a restricted flow path. Manufacturing method. 8. The adapter when the structure defines a recess and the dimensions of the structure are aligned with the recesses on the upper surface of the adapter plate (26). 8. The method according to claim 7, wherein a passage is defined through the plate (26). 9. The micromachining technology includes photolithography, X-ray lithography, electroforming and laser micromachining technology.
3. The method for manufacturing an injection device according to claim 1.