CN111720248A

CN111720248A - Fuel injector

Info

Publication number: CN111720248A
Application number: CN202010194470.1A
Authority: CN
Inventors: B·陶贝-达明; C·克莱因; M·赫雷拉; M·温格尔; M·克劳泽; O·蒂克尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-03-19
Filing date: 2020-03-19
Publication date: 2020-09-29
Also published as: DE102019203658A1

Abstract

The invention relates to a fuel injector (10) having an injector housing (12) in which a nozzle needle (16) is arranged, which can be moved back and forth along a longitudinal axis (18) for closing and opening an injection opening (20), wherein the movement of the nozzle needle (16) is controlled by a hydraulic pressure prevailing in a control chamber (40), wherein the control chamber (40) is hydraulically connected to a high-pressure chamber (15) via an inlet opening (52), wherein the high-pressure chamber (15) is supplied with fuel under pressure via an inlet channel (34; 34 b). According to the invention, a distance formed in the direction of the longitudinal axis (18) is provided between a first inflow opening (56) of the supply channel (34) into the high-pressure chamber (15) and a second inflow opening (58) of the supply opening (52) on the side facing away from the control chamber (40), wherein the first inflow opening (56) has a smaller distance in the direction of the longitudinal axis (18) than the second inflow opening (58) relative to the injection opening.

Description

Fuel injector

Technical Field

The present invention relates to a fuel injector, which is used in particular as a component of a common rail system for injecting fuel into a combustion chamber of a self-igniting internal combustion engine.

Background

A fuel injector is known from EP 2347115B 1 of the applicant. In the known fuel injector, a valve part is arranged in the injector housing, which valve part has a bore on the side facing the at least one injection opening, into which bore an axial end region of the nozzle needle is countersunk. The bore delimits, together with the nozzle needle, a control chamber which can be relieved via an outflow channel with an integrated outflow throttle into a low-pressure region of the fuel injector. The fuel flows into the control chamber via an inflow opening which is formed in the valve part in a wall which radially surrounds the longitudinal axis of the valve part or of the nozzle needle. The inflow opening is hydraulically connected to the high-pressure chamber. The high-pressure chamber is in turn hydraulically coupled via an inflow channel with a fuel supply (in particular a rail) which is under high pressure. The inflow openings of the inflow channels into the high-pressure chamber and the inflow openings of the inlet openings on the side facing away from the control chamber into the control chamber are located at the same height with respect to the longitudinal axis, but, for example, on opposite sides, i.e., are offset by 180 ° from one another, wherein the angular positions of the inflow channels and the inflow openings and the inlet openings are random.

Disclosure of Invention

The fuel injector of the present invention has the following advantages: it is particularly firmly constructed with respect to the particles flowing into the control chamber via the inlet channel. In particular, the fuel injector of the present disclosure may minimize the amount of such particles that may flow into the control chamber. The invention is based on the idea that the flow path for the fuel flowing into the high-pressure chamber via the inlet channel in the direction of the inlet opening is geometrically arranged or configured in such a way that, when the fuel flows from the first inlet opening in the region of the inlet channel in the direction of the second injection opening in the region of the inlet opening, the particles possibly entrained by the fuel do not reach the region of the second inlet opening or the inlet opening as far as possible. For this purpose, the invention shows two different solutions, which can be applied individually or in combination with one another.

In a first basic configuration of the fuel injector according to the teaching of the first solution according to the invention, it is provided that a distance configured in the direction of the longitudinal axis is provided between a first inflow opening of the inlet channel into the high-pressure chamber and a second inflow opening of the inlet bore on the side facing away from the control chamber, wherein the first inflow opening has a smaller distance in the direction of the longitudinal axis than the second inflow opening with respect to the at least one injection opening.

In other words, the first configuration therefore provides that the supply channel opens into the control chamber in the region of the injector housing or of the high-pressure chamber below the inflow opening of the supply opening. This has the effect that, when the fuel flows from the supply channel in the direction of the supply opening, particles which may be present move in the direction of the injection opening and therefore cannot reach the region of the second inflow opening of the supply opening, due to gravity or due to the arrangement of the fuel injector in the combustion chamber of the internal combustion engine.

For this purpose, it is particularly advantageous if the cross sections of the two inflow openings do not coincide, as seen in the longitudinal direction, i.e. are arranged without overlapping one another. The greater the axial distance between the two inflow openings or between the two cross sections, the higher the probability that "particles entrained by the fuel do not reach the control chamber".

In a further embodiment of the consideration, it can be provided that the central axes of the two inflow openings are each arranged perpendicularly to the longitudinal axis and intersect it, and that the second inflow opening of the inlet bore is arranged at least approximately on the side opposite the first inflow opening of the inlet channel with respect to the longitudinal axis. This design makes it possible, on the one hand, to achieve a relatively simple production method for the inflow channel and the inflow opening, and, on the other hand, to maximize the path length of the fuel flowing through the inlet channel in the direction of the inlet opening by arranging the second inlet opening of the inlet opening, preferably offset by 180 ° with respect to the first inlet opening of the inlet channel.

In a basic configuration of the invention according to the teaching of the second solution of the invention, which is provided differently from the above-described proposal or additionally thereto, it is provided that the first inflow opening of the inlet channel into the high-pressure chamber opens into the high-pressure chamber perpendicularly to the longitudinal axis and in the tangential direction, and that the second inflow opening of the inlet bore, viewed in the circumferential direction around the longitudinal axis, is arranged on the side facing away from the control chamber in the vicinity of the first inflow opening of the inlet channel, in particular at an angle of between 45 ° and 5 ° with respect to the position of the first inflow opening, so that a flow path is formed between two inflow openings in the high-pressure chamber in the circumferential direction around the longitudinal axis, which flow path encloses an angle of between 315 ° and 355 °.

This design of the fuel injector results in the fuel flowing into the high-pressure chamber via the supply channel flowing in the tangential direction in the direction of the inflow opening into an annular gap between a component (valve element) radially surrounding the control chamber and the injector housing. In this case, the defined or according to the invention provided position of the second inflow opening of the inlet opening maximizes the flow length or flow path of the fuel in the direction of the control chamber, so that the probability of particles, which are brought into the high-pressure chamber via the inlet channel, reaching the area of the inflow opening and thus the control chamber is also minimized here, in particular due to the effect of gravity.

In a further development of the last proposed solution, it is provided that the central axis of the inlet opening is arranged at an angle of inclination of less than 90 ° with respect to a tangent to the wall of the valve element in the region of the second inflow opening of the inlet opening on the side facing away from the inlet channel, so that the central axis of the inlet opening does not intersect the longitudinal axis. In this case, it is necessary for the fuel to perform a direction reversal or deflection in order to achieve a flow of fuel from the high-pressure chamber into the control chamber, in which case the particles, due to their mass, tend to contribute less to the flow reversal or deflection and therefore flow past the region of the second inflow opening.

In a further development of the last proposed solution, it is advantageous if the angle of inclination is less than 70 °.

In view of the geometry of the injector housing or the strength of the nozzle rod, it is provided in an advantageous embodiment that the inlet opening is formed in the region of a wall of the valve part which radially surrounds the longitudinal axis, and that the inflow duct is arranged in the region of the valve part, viewed in the direction of the longitudinal axis.

In an alternative arrangement of the inlet channel (which additionally minimizes the circumstances in terms of flow technology in the direction of minimizing particles rushing into the control chamber), the inlet opening is formed in the region of a wall of the valve part radially surrounding the longitudinal axis, and the inlet channel is arranged below the valve part on the side facing the at least one inlet opening, viewed in the direction of the longitudinal axis.

Further advantages, features and details of the invention emerge from the following description of a preferred embodiment and from the drawings.

Drawings

Figure 1 shows a portion of a fuel injector in a longitudinal cross-sectional view,

figure 2 shows in an enlarged view in longitudinal section a part region of the fuel injector according to figure 1,

fig. 3 shows a cross section in the region of the control chamber in a modified embodiment of the fuel injector.

In the figures, identical elements or elements having identical functions are provided with the same reference numerals.

Detailed Description

Fig. 1 shows a fuel injector 10 in part for injecting fuel into a combustion chamber, not shown, of a self-igniting internal combustion engine. The fuel injector 10 has an injector housing 12, which forms a high-pressure chamber in the region of a slot 14 of the injector housing 12 for storing fuel at high pressure or system pressure. Furthermore, a valve element in the form of a nozzle needle 16 is arranged to be reciprocatable along a longitudinal axis 18 within the slot 14 of the injector housing 12.

The nozzle needle 16 serves to open or close at least one injection opening 20 formed on the side of the valve housing 12 facing the combustion chamber of the internal combustion engine. In the position of the nozzle needle 16 shown in fig. 1, the nozzle needle 16 is arranged in its lowered position in which the at least one injection opening 20 is at least indirectly closed by the formation of a sealing seat 22 between the nozzle needle 16 and the at least one injection opening 20.

An axial end region 24 of the nozzle needle 16 facing away from the at least one injection opening 20 dips into a bore 26 of a valve part 28, wherein a wall 30 of the valve part 28 radially surrounding the longitudinal axis 18 guides the end region 24 radially and sealingly surrounds it. Furthermore, a radial gap 32 is formed between the circumferential surface of the wall 30 of the valve element 28 and the groove opening 14, which radial gap enables the fuel to flow in from the region of the supply channel 34 in the direction of the high-pressure chamber 15. In general, the supply channel 34 opens out on the outside of the injector housing 12 in the region of a fuel rail (not shown), which can be connected to a fuel accumulator (rail) at high pressure.

The valve member 28 rests with the underside of the increased-diameter section 35 on a sealing surface 36 of the slot 14 arranged radially about the longitudinal axis 18 and is clamped axially against the sealing surface 36 by means of a clamping tool not shown. The supply channel 34, which opens laterally, for example perpendicularly to the longitudinal axis 18, into the high-pressure chamber 15, may also open into the high-pressure chamber 15 at an oblique angle to the longitudinal axis 18, or may have an annular groove (not shown in both embodiments) running radially around the longitudinal axis 18.

The bore 26 in the valve part 28 delimits, in a known manner, a control chamber 40 together with the wall 30 and the axial end region 24 of the nozzle needle 16. Control chamber 40 may be relieved via an outflow channel 42 having an integrated outflow throttle 44 into a low-pressure region 46 of injector housing 12, wherein outflow channel 42 is arranged coaxially with longitudinal axis 18. The valve member 28 has a sealing surface 50 on the side of the outflow channel 42 facing away from the control chamber 40, which sealing surface 50 is designed to form a sealing seat with a closing element (for example, as a component of a solenoid armature) not shown in fig. 1. In the case of the formation of the sealing seat, the discharge of fuel from the control chamber 40 into the low-pressure region 46 is prevented, whereas in the case of the discharge channel 42 being released, the discharge of fuel from the control chamber 40 into the low-pressure region 46 (as is known per se from the prior art) is carried out in order to lift the nozzle needle 16 from the sealing seat 22.

In order to fill control chamber 40 with fuel at high pressure or system pressure, valve element 28 has an inflow opening 52 in the region of wall 30. The inflow opening 52 extends in the illustrated embodiment perpendicularly to the longitudinal axis 18 and has a cross-sectional narrowing for forming an inlet throttle 54.

In the exemplary embodiment shown in fig. 1 and 2, the first inflow opening 56 of the supply duct 34 opens into the high-pressure chamber 15 with respect to the longitudinal axis 18, for example, on the side opposite the second inflow opening 58 of the supply bore 52 (i.e., offset by 180 °). Furthermore, the cross section A of the first inflow opening 56₁Larger than the cross section A of the second inflow opening 58₂。

It is also important that the first inflow opening 56 opens into the high-pressure chamber 15 below the second inflow opening 58, i.e. on the side facing the at least one injection opening 20, as viewed in the direction of the longitudinal axis 18. In particular, it is provided with reference to fig. 2 that the distance a extending between the two

center axes

61, 62 of the two

inflow openings

56, 58 or between the input channel 34 and the two

center axes

61, 62 of the input bore 52 in the direction of the longitudinal axis 18 is at least equal to the two radii r of the two

inflow openings

56, 58₁And r₂As large as the sum. This ensures that the two

inflow openings

56, 58 do not intersect, viewed in the direction of the longitudinal axis 18. However, the distance a is preferably greater, so that between the two

inflow openings

56, 58 or in the two cross sections a₁And A₂Forming an additional distance or distance therebetween. In any case, the first inflow opening 56 is thus at a smaller distance from the at least one spray opening 20 than the second inflow opening 58, as viewed in the direction of the longitudinal axis 18.

Fig. 3 shows a further embodiment of the arrangement or configuration of the feed channel 34a and the feed opening 52 a. In particular, it can be seen that the inlet channel 34a opens into the high-pressure chamber 15 tangentially with respect to the radial gap 32 or the injector housing 12. It can also be seen that the central axis 62a of the inflow opening 52a is arranged in the vicinity of the first inflow opening 56a, viewed in the circumferential direction about the longitudinal axis 18. The exemplarily depicted flow path 64 of the fuel flowing from the inlet channel 34a into the high-pressure chamber 15 is directed counterclockwise in the circumferential direction in the direction of the inflow opening 52 a. In particular, it can be seen that the two

central axes

61a, 62a have an angle β of between 5 ° and 25 ° relative to one another, so that the length of the flow path 64 for the fuel between the two

inflow openings

56a, 58a corresponds in the counterclockwise direction to an angle of between 335 ° and 355 °. The central axis 62a of the inflow opening 52a has an angle γ of at most 70 ° with respect to the tangent 65 in the region of the inflow opening 58a, so that the fuel flowing into the inlet opening 52a must undergo a strong change in direction.

Finally, it is also alternatively conceivable, corresponding to the illustration in fig. 1, for the supply channel 34b to open into the high-pressure chamber 15 below the region of the valve element 28 with respect to the longitudinal axis 18. Here, it can also be seen that the supply channel 34b can be arranged at an angle a relative to the longitudinal axis 18 or open into the high-pressure chamber 15. The input channel 34 is omitted from the configuration of the input channel 34 b.

The fuel injector 10 described thus far may be modified or adapted in various ways without departing from the inventive concept. In particular, it is conceivable to combine the features of the embodiment according to fig. 1 and 2, i.e. the distance a extending in the longitudinal direction between the first inflow opening 56 of the inlet channel 34 into the high-pressure chamber 15 and the second inflow opening 58 of the inlet bore 52, with the features of the embodiment according to fig. 3, i.e. the fuel flow path extending in the circumferential direction around the valve member 28.

Claims

1. A fuel injector (10) having an injector housing (12) in which a nozzle needle (16) is arranged, which is movable to and fro along a longitudinal axis (18) for closing and opening at least one injection opening (20), wherein the movement of the nozzle needle (16) can be controlled by a hydraulic pressure prevailing in a control chamber (40), wherein the control chamber (40) is hydraulically connected to a high-pressure chamber (15) via an input bore (52), wherein the high-pressure chamber (15) can be supplied with fuel under pressure via an input channel (34; 34b),

characterized in that a distance (a) configured in the direction of the longitudinal axis (18) is provided between a first inflow opening (56) of the inlet channel (34) into the high-pressure chamber (15) and a second inflow opening (58) of the inlet bore (52) on the side facing away from the control chamber (40), wherein the first inflow opening (56) has a smaller distance in the direction of the longitudinal axis (18) than the second inflow opening (58) with respect to at least one injection opening.

2. A fuel injector according to claim 1, characterized in that the two inflow openings (56, 58) have a cross-section (A) viewed in the direction of the longitudinal axis (18)₁，A₂) Are not coincident.

3. The fuel injector as claimed in claim 1 or 2, characterized in that the central axes (61, 62) of the two inflow openings (56, 58) are each arranged perpendicularly to the longitudinal axis (18) and intersect the longitudinal axis (18), and the second inflow opening (58) of the inlet bore (52) is arranged at least approximately on the side opposite the first inflow opening (56) of the inlet channel (34) with respect to the longitudinal axis (18).

4. A fuel injector (10) having an injector housing (12) in which a nozzle needle (16) is arranged, which is movable to and fro along a longitudinal axis (18) for closing and opening at least one injection opening (20), wherein the movement of the nozzle needle (16) can be controlled by a hydraulic pressure prevailing in a control chamber (40), wherein the control chamber (40) is hydraulically connected to a high-pressure chamber (15) via an input bore (52a), wherein the high-pressure chamber (15) can be supplied with fuel under pressure via an input channel (34a),

characterized in that a first inflow opening (56a) of the inlet channel (34a) into the high-pressure chamber (15) opens into the high-pressure chamber (15) perpendicularly to the longitudinal axis (18) and tangentially, and in that a second inflow opening (58a) of the inlet bore (52a) is arranged next to the first inflow opening (56a) of the inlet channel (34a) on the side facing away from the control chamber (40) viewed in the circumferential direction around the longitudinal axis (18), wherein a flow path (64) is formed between the two inflow openings (56a, 58a) in the high-pressure chamber (15) in the circumferential direction around the longitudinal axis (18), which flow path encloses an angle () of between 315 ° and 355 °.

5. A fuel injector according to claim 4, characterized in that the centre axis (62a) of the input bore (52a) is arranged on the side facing away from the input channel (34a) with an angle of inclination (γ) of less than 90 ° with respect to a tangent (65) on the wall (30) of the valve element (28) in the region of the second inflow opening (58a) of the input bore (52a) such that the centre axis (62a) of the input bore (52a) does not intersect the longitudinal axis (18).

6. A fuel injector according to claim 5, characterized in that the angle of inclination (γ) is at most 70 °.

7. A fuel injector according to one of claims 1 to 6, characterized in that the inlet opening (52; 52a) is formed in the region of a wall (30) of the valve element (28) which radially surrounds the longitudinal axis (18), and the inflow channel (34; 34a) is arranged in the region of the valve element (28) as viewed in the direction of the longitudinal axis (18).

8. Fuel injector according to one of the preceding claims 1 to 6, characterized in that the inlet opening (52; 52a) is formed in the region of a wall (30) of the valve element (28) which radially surrounds the longitudinal axis (18), and in that the inflow channel (34b) is arranged below the valve element (30) on the side facing the at least one injection opening (20) as viewed in the direction of the longitudinal axis (18).

9. Fuel injector according to one of claims 1 to 8, characterized in that the first inflow opening (56; 5)6a) Cross section of (A)₁) Is larger than the second inflow opening (58; 58a) cross section of (A)₂)。

10. The fuel injector as claimed in one of claims 1 to 9, characterized in that the inlet opening (52; 52a) has an inlet throttle (54).