KR101029214B1 - Fuel injector - Google Patents

Abstract

At one of its ends, an injector needle (IN) (6) has a seating area in a nozzle/jet unit (7) and, at its other end, supports a bush (1) that sits on the IN's periphery and slides in relation to the IN. With springy support on the IN, the bush defines a control chamber (10) against a fuel injector's component linking on-axis to the nozzle/jet unit.

Description

Fuel Injector {FUEL INJECTOR}

The invention relates to a fuel injector for injecting fuel stored at high pressure in a fuel reservoir into the combustion chamber of an internal combustion engine according to the preamble of claim 1.

BACKGROUND OF THE INVENTION A fuel injector (common rail injection system) for injecting fuel stored at high pressure in a fuel reservoir into a combustion chamber of an internal combustion engine is known. Such fuel injectors typically have two hydraulic fluid channels. The main channel extends from the injector inlet to the spray nozzle, the second channel branching at the appropriate point of the main channel to the servovalve, which switches the control pressure of the control chamber in connection with the opening and closing of the nozzle needle. .

The fuel always contains particles of a given size or less. Thus, many known injectors are provided on the inlet side with a filter or other component that filters out particles that exceed the size harmful to the injector.

The control valve provided for the control of the injector should convert the supplied electrical control signal into a change in control pressure as soon as possible, the faster the valve's response behavior.

 Acceleration of the switching speed is achieved in particular by the stroke reduction of the valve control member. This, of course, means that particles larger than the stroke cannot penetrate the valve gap and become stuck in the valve gap, thus impeding the function of the valve.

If the inlet filter described above is further refined in relation to the allowable particle size, the flow resistance gradually increases and at the same time the adverse effect on the hydraulic properties of the injector increases correspondingly.

A fuel injector for injecting fuel stored at high pressure in a fuel reservoir into a combustion chamber of an internal combustion engine, known from WO 01/11222 A1, is provided by an injector housing, a nozzle needle arranged to move longitudinally within the housing and the nozzle needle. And an injection nozzle that is selectively opened, through which the fuel can be injected into the combustion chamber of the internal combustion engine. The control chamber, which receives fuel pressure and interacts with the nozzle needle with respect to the selective opening and closing of the injection nozzle, is defined by a bushing surrounding the nozzle needle, the fuel supplied circulates through the bushing, and by the bushing the control chamber The inflow channel to the furnace is opened. Filters arranged at the inlet to the control chamber of the fuel injector are already known from EP 0 957 262 A2 and DE 100 37 388 A1.

The object of the present invention is to improve a fuel injector of the type described above. In particular, it is necessary to provide a fuel injector that is generally insensitive to foreign particles contained in the feed fuel.

The problem is solved through a fuel injector having the features of claim 1.

Embodiments and preferred refinements of the fuel injector according to the invention are set out in the dependent claims.

Through the present invention, a fuel injector for an internal combustion engine is provided that includes an axial bore through which fuel flows through a nozzle body. The bore receives a nozzle needle movably guided axially within the nozzle body, the nozzle needle having a seating surface on the nozzle body at one end and disposed around the nozzle needle at the other end of the nozzle needle. Support the bushing to move relative to. The bushing is connected to a fuel circulation chamber on the outer side of the bushing through an inlet channel in the bushing, with the bush needle elastically supported at a position opposite the axial component of the fuel injector connected to the nozzle body. It forms a chamber and includes an outlet channel controlled by a control valve. According to the invention the bushing is provided with a filter for filtration of fuel flowing through the inlet channel into the control chamber.

One of the main advantages of the present invention is that the control circuit is reliably protected against very small particles, while the flow to the input injection is much less sensitive to relatively large particles in the main channel. Is maintained.

According to one preferred embodiment of the invention, a filter is provided around the bushing.

Preferably the filter is annularly designed to surround the bushing.

According to one preferred embodiment of the invention the filter is designed in the form of a cylindrical face.

Preferably the bushing is designed to have two sections with different perimeters, and the filter is arranged at an inwardly entered diameter of the bushing, which is smaller in perimeter.

The bushing preferably has a shape in which the diameter enters more in comparison with the section opposite the control chamber from the region of the control chamber side section to the edge, the diameter difference forming a radial end for installing the filter on the end side.

Preferably, the inwardly entered diameter forms a recess in the form of an annular groove with two radial ends which receive the filter.

According to one preferred embodiment of the present invention, a recess is formed in the bushing to receive fuel flow further through the filter inside the filter.

Preferably the recess is designed in the form of an annular groove.

The inlet channel into the control chamber preferably includes an inlet throttle to limit the inlet volume.

According to one preferred embodiment of the invention, the inlet channel to the control chamber comprises a preliminary chamber for collecting the inlet flow.

According to one preferred embodiment of the invention, an inlet channel into the control chamber is formed inside the bushing.

According to another preferred embodiment of the invention, an inlet channel to the control chamber is formed in the shaft of the nozzle needle.

The filter may be formed of a wire mesh.

The filter may be formed of a woven laminate.

The filter may be formed of a sintered material.

The filter may be formed as a disk filter.

The filter may be formed as a filter with holes, in particular round, oval or polygonal holes.

Preferably the filter is fixed to the bushing by welding.

According to one preferred embodiment of the invention, the filter is self-cleaning by placing it in the fuel flow to be injected.

Hereinafter, with reference to the drawings will be described an embodiment of a fuel injector according to the present invention.

1 is a partial cross-sectional view of a fuel injector according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A of FIG. 1.

3 is a modification of the detailed view of FIG. 2.

* Drawing code list *

1: bushing

2: inlet throttle

3: filter

4: exhaust throttle

5: spring

6: nozzle needle

7: injector housing, nozzle body

8: high pressure channel, axial bore

9: spare chamber

10: control chamber

11: inward diameter

12: home

13: spray nozzle

14: nozzle spare chamber

1 shows a portion of a fuel injector provided for injecting fuel stored at high pressure in a fuel reservoir (common rail) not shown. The fuel injector comprises an injector housing with a nozzle body 7, only a portion of which is shown, in which the nozzle needle 6 is arranged to move in the longitudinal direction. The nozzle needle interacts with the seating surface on the nozzle body 7, provided at one end thereof, to selectively open the injection nozzle 13 for injecting fuel. Fuel stored at high pressure in the fuel reservoir is nozzle preliminary chamber annularly surrounding the peak periphery of the nozzle needle 6 via a high-pressure channel 8 formed in the form of an axially extending bore in the nozzle body 7. 14). The nozzle needle 6 is guided to move longitudinally in the axial bore 8.

At the other end of the nozzle needle 6, a bushing 1 which is arranged around the nozzle needle and moves relative to the nozzle needle 6 is supported. The bushing 1 is elastically supported by the nozzle needle 6 and through the inlet channels 2, 9 in the bushing 1 with respect to the fuel injector component axially connected to the nozzle body 7. Limit the control chamber 10 in connection with the fuel circulation chamber on the outer side of 1).

The control chamber 10 is pressurized by the fuel supplied at high pressure, and the pressure can be selectively reduced in relation to the opening of the injection nozzle 13 to the discharge throttle 4 by a control valve not shown in the drawing. .

As can be seen in the enlarged detail of two variants, shown in FIG. 1 and in particular in FIGS. 2 and 3, the control chamber 10 surrounds the nozzle needle 6 and the bushing 1 abuts the nozzle needle. Perimeter is limited, and the bushing is perfused by the fuel supplied through the high pressure bore (8). The bushing 1 opens the inlet channels 2, 9 including the inlet throttle 2, leading to the control chamber 10.

The bushing 1 is provided with a filter 3 for filtering the fuel supplied to the control chamber 10, the filter being annularly designed to enclose the circumference of the bushing 1 and in the form of a cylindrical face. The outer perimeter of the bushing 1 has entered inwardly to receive the filter 3. According to FIG. 2, the inwardly entered diameter 11 forms an annular groove, in which the filter 3 lies between the two radial ends of the groove. According to FIG. 3, a diameter 11 entered inwardly in a part of the bushing extends to the upper end of the bushing 1, whereby the filter has a radius of the lower part formed by the diameter entered inwards, above the bushing 1. The advantage of the assembly side is obtained, which can be slid to the stop located at the directional end. The filter 3 (preferably wire mesh) can be shaped as a fabric cylinder separately from the bushing 1. Bushing 1 is spot-welded with the fabric cylinder.

The bushing 1 is also provided with a recess designed in the form of an annular groove 12 which receives the fuel flow through the filter 3 in the region of the inside of the filter 3 and inwardly in diameter 11. do.

The inlet channel leading to the control chamber 10 comprises an inlet throttle 2 for limiting the inlet flow, already described above, and preliminary to collect the inlet flow at the transition from the groove 12 to the inlet throttle 2. Has a chamber 9. According to FIG. 3 the inlet throttle 2 leading into the control chamber is oriented such that its inlet cannot be placed directly under the outlet throttle 4. Correspondingly, the perimeter of the upper end of the nozzle needle 6 enters slightly inward.

In the illustrated embodiments, inlet channels 2, 9 leading to the control chamber 10 are formed in the bushing 1. Alternatively, an inlet channel into the control chamber 10 may be formed in the shaft of the nozzle needle 6. In this case, the bushing 1 should have a suitable recess to allow access to the inlet channel.

The filter 3 may be formed from a cylindrical wire mesh made of wires extending in the circumferential and longitudinal directions. Preferably the wires are thicker extending longitudinally, ie coaxially to the bushing, to ensure sufficient strength. To prevent the wires from moving, the wire mesh must be sintered. As an alternative, the filter 3 may be formed of a fabric composite or a sintered material. According to a further alternative embodiment the filter 3 may be formed as a disk filter or a hole, in particular a filter with circular, elliptical or polygonal holes.

The filter 3 is self cleaning. The particles settled there by the fuel flowing out of the filter 3 in the high pressure bore 6 are wiped out together and injected together with the fuel through the injection nozzle 13 into the combustion chamber of the internal combustion engine, Even in internal combustion engines). Thus, maintenance of the filter 3 is not necessary.

Claims (21)

A fuel injector for an internal combustion engine comprising an axial bore 8 through which fuel to be injected in the nozzle body 7 flows. The bore accommodates a nozzle needle 6 which is guided axially within the nozzle body 7, the nozzle needle 6 having a seating surface on the nozzle body at one end and at the other end. It is arranged around the nozzle needle 6 to support a bushing 1 which is movable relative to the nozzle needle 6, the bushing opposing an axial component of the fuel injector connected to the nozzle body 7. Control chamber 10 connected to the fuel circulation chamber outside of the bushing 1 via inlet channels 2, 9 in the bushing 1, with the nozzle needle 6 being resiliently supported. In the fuel injector for an internal combustion engine, the control chamber includes an exhaust channel (4) controlled by a control valve, Characterized in that the bushing (1) is provided with a filter (3) for filtration of fuel flowing through the inlet channels (2, 9) to the control chamber (10), Fuel injectors for internal combustion engines. The method of claim 1, Characterized in that the filter (3) is provided around the bushing (1), Fuel injectors for internal combustion engines. 3. The method of claim 2, It is characterized in that the filter 3 is designed in an annular fashion so as to surround the bushing 1, Fuel injectors for internal combustion engines. The method of claim 3, wherein The filter 3 is characterized in that designed in the form of a cylindrical outer surface, Fuel injectors for internal combustion engines. The method of claim 1, The bushing 1 comprises two sections with different perimeters, the filter 3 being arranged at an inwardly entered diameter 11 of the bushing 1, which is smaller in perimeter, Fuel injectors for internal combustion engines. The method of claim 5, The bushing 1 has a shape in which the diameter enters inward more than the section opposite the control chamber from the region of the control chamber side section to the edge, and this diameter difference is provided with a radial end for installing the filter 3 at the end side. Characterized in that, Fuel injectors for internal combustion engines. The method of claim 5, It is characterized in that the inwardly entered diameter 11 forms a recess in the form of an annular groove with two radial ends which receive the filter 3, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, A recess 12 is formed in the region of the diameter 11 which enters into and inside the filter 3 in the bushing 1 to receive the fuel flow passing through the filter 3. Fuel injectors for internal combustion engines. The method of claim 8, Characterized in that the recess 12 is designed in the form of an annular groove, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Characterized in that the inlet channels (2, 9) leading to the control chamber 10 includes an inlet throttle (2) limiting the inlet amount, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Inlet channel (2, 9) to the control chamber 10, characterized in that it comprises a preliminary chamber (9) for collecting the inlet flow, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Characterized in that the inlet channels (2, 9) leading to the control chamber 10 is formed inside the bushing (1), Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, It is characterized in that inlet channels (2, 9) leading to the control chamber (10) are formed in the shaft of the nozzle needle (6), Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, The filter 3 is characterized in that it is formed of a wire cloth, Fuel injectors for internal combustion engines. 15. The method of claim 14, Characterized in that the wire mesh is sintered, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Characterized in that the filter 3 is formed of a woven laminate, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Characterized in that the filter 3 is formed of a sintered material, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Characterized in that the filter 3 is formed of a disk filter, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, Characterized in that the filter 3 is formed of a filter having circular, elliptical or polygonal holes, Fuel injectors for internal combustion engines. 15. The method of claim 14, Characterized in that the filter 3 is fixed to the bushing 1 by welding, Fuel injectors for internal combustion engines. The method according to any one of claims 1 to 7, The filter 3 is characterized in that it is self-cleaning by placing it in the fuel flow to be injected, Fuel injectors for internal combustion engines.

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