CN114761681B

CN114761681B - Fuel injection valve with slide valve for internal combustion engine

Info

Publication number: CN114761681B
Application number: CN202080083944.3A
Authority: CN
Inventors: M·甘瑟
Original assignee: Ganser Hydromag AG
Current assignee: Ganser Hydromag AG
Priority date: 2019-12-03
Filing date: 2020-12-01
Publication date: 2024-01-16
Anticipated expiration: 2040-12-01
Also published as: WO2021110663A1; CN114761681A; JP2023504727A; EP4069963A1

Abstract

A fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine has a spool valve body guided in a sliding fit portion. The slide valve body is formed with a pocket-shaped recess centered on the longitudinal axis, starting from a first end face facing the control chamber. From the bottom of the recess not only the throttle inlet but also the throttle channel leads to the second end side. The throttle duct can be connected to the high-pressure chamber via a throttle inlet likewise formed in the slide valve. If the slide valve body is in contact with the control body, the throttle inlet is closed and the throttle duct and the control duct are connected to one another. However, if the slide valve body is lifted from the control body at the end of the injection process, a gap is formed which releases the throttle inlet, so that fuel can flow from the high-pressure chamber into the control chamber via the throttle inlet and the throttle channel.

Description

Fuel injection valve with slide valve for internal combustion engine

Technical Field

The present invention relates to a fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine.

Background

A fuel injection valve of this type is known from document EP 1 273 791 A2. The fuel injection valve shown in fig. 6 of this document has a slide valve body guided in a hollow-cylindrical sleeve with a tight sliding fit, said slide valve body having a first end face facing the control chamber and a second end face opposite the first end face. The throttle inlet extends from the second end side to the first end side, wherein the throttle inlet has a throttle constriction at a distance from the second end side and at a further distance from the first end side. Furthermore, a throttle duct extends from the first end face to the second end face, which throttle duct has a further throttle constriction at a corresponding same distance from the throttle inlet. A throttle inlet extending in the radial direction is formed on the slide valve body, and opens into the throttle channel. The control body, which is arranged in a fixed manner, forms with its front side facing the slide valve body a slide valve seat which cooperates with the second end side of the slide valve body. The control body has a control channel which starts from the front side, is continuously connected with the throttling channel in a flow manner, can be connected with the low-pressure cavity by means of a pilot valve and can be disconnected with the low-pressure cavity. The throttle duct and the control duct are continuously connected in flow communication with the high-pressure chamber via a throttle inlet. When the slide valve body is lifted from the slide valve seat, a gap is formed, via which the throttle duct and the control duct are additionally connected in flow connection, and the throttle inlet is connected in flow connection with the high-pressure chamber.

The eccentrically formed adhesive surface between the second end side of the slide valve body and the front side of the control body leads to a delay in the response of the fuel injection valve in order to end the injection process. Furthermore, the production is complicated because the slide valve body must be constructed accurately and, in particular, the throttle inlet, the throttle duct and the throttle constriction of the throttle inlet must be produced with very small tolerances.

Disclosure of Invention

The object of the invention is therefore to further develop a fuel injection valve of the same type in such a way that the delay in response is minimized while at the same time being simple to produce.

This object is achieved by a fuel injection valve according to the invention for intermittent injection of fuel into a combustion chamber of an internal combustion engine.

The fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine includes: a housing having a high pressure inlet for fuel at very high pressure (up to 2000bar or more); and a jet valve seat.

In the interior of the housing, a high pressure chamber extends from the high pressure inlet to the injection valve seat.

An injection valve part is arranged in the housing so as to be movable in the longitudinal direction, said injection valve part applying the force of a closing spring against the direction of the injection valve seat and being designed to interact with the injection valve seat. In the rest state, the injection valve part rests against an injection valve seat and thus prevents the injection of fuel from the high-pressure chamber into the combustion chamber of the internal combustion engine in a known manner. To trigger the injection process, the injection valve part is lifted from the injection valve seat against the force of the locking spring. To end the injection process, the injection valve part then again rests against the injection valve seat.

A double-acting control piston is formed on the injection valve part, which defines a high-pressure chamber with its side facing the injection valve seat and a control chamber with its side facing away from the injection valve seat.

Preferably, the control chamber is delimited on the circumferential side by a sleeve, preferably of hollow cylindrical shape, on which the control piston is guided with a tight sliding fit and on which the locking spring is supported, which is supported on the other side on the injection valve part and which is loaded with its spring force toward the injection valve seat.

The control piston can be guided in a sliding manner instead of on a component formed on the sleeve, on the housing itself or in a different manner, which component is arranged in the housing, wherein the housing or the component delimits the control chamber on the circumferential side.

The slide valve can be guided freely movable in the direction of the longitudinal axis with a preferably tight sliding fit defining the longitudinal axis. The spool valve body has a first end side facing the control chamber, defining the control chamber, and a second end side facing away from the first end side and thus from the control chamber in the longitudinal direction.

Preferably, the spool valve body has an outer wall that is at least approximately rotationally symmetrical about the longitudinal axis.

If necessary, the sliding fit is likewise formed on the sleeve or on the housing or the component.

In addition, a control body is fixedly arranged in the housing with respect to the housing, with which the control body forms a slide valve seat which cooperates with the second end side of the slide valve body towards the front side of the slide valve body.

Preferably, the sleeve is held against the control body by the force of the locking spring acting on it.

In addition, the spool valve body has a throttle passage disposed between the first end side and the second end side.

The control body has a control channel which starts from the front side of the control body, is continuously connected with the throttle channel in a flow manner, can be connected with the low-pressure cavity by means of a pilot valve at the other end and can be disconnected with the low-pressure cavity.

The preferably existing constriction of the control channel is located in the end region of the control channel facing the low-pressure chamber.

The control channel and the throttle channel can be connected to the high-pressure chamber via a throttle inlet formed in the slide valve body, at least at the end of the injection process, preferably continuously.

The slide valve body also has a throttle inlet opening out of the second end face into the control chamber, which is closed by the control body when the slide valve body is in contact with the control body.

If the slide valve body is lifted from the control body, a gap is formed between them, via which gap the throttle channel, the control channel and the throttle inlet are connected to the high-pressure chamber. The gap is closed when the slide valve body is in contact with the control body.

In order to connect the gap to the high-pressure chamber, the sleeve optionally has a channel in its end region facing the control body, which channel is connected to the high-pressure chamber.

According to the invention, a pocket-shaped recess, which is centered on the longitudinal axis and is preferably rotationally symmetrical, is integrally formed on the slide valve body, starting from its first end face.

From the recess, preferably from its bottom, which is preferably planar and extends perpendicularly to the longitudinal axis, the throttle channel extending toward the second end face leaves, and the throttle inlet from the second end face preferably opens into the recess in the region of the bottom of the recess.

Since the recess starts from the first end side of the spool valve body, the volume of the recess is part of the control chamber.

The recess enables not only the throttle channel but also the throttle inlet to be formed shorter than known from the prior art, which simplifies their manufacture.

Furthermore, the embodiment of the slide valve body according to the invention enables the throttle duct and the throttle inlet to be formed closely next to one another and in the vicinity of the longitudinal axis. An adhesive surface between the control body and the slide valve body with a pronounced eccentricity about the longitudinal axis can thereby be avoided; the adhesion surface has a smaller eccentricity than the prior art. By these measures, the response characteristics of the fuel injection valve are improved over the prior art. On the one hand, the delay in the response is lower, which means that a more rapid response characteristic is present at the end of the injection process, and on the other hand, the stability of the movement of the slide valve body is also improved due to the symmetrical pressure distribution, which is significant in particular in the case of multiple injections and which balances the operating characteristics of the same-designed fuel injection valve.

Preferably, the throttle duct has a preferably pocket-shaped recess formed in the slide valve body, which recess opens toward the second end face, into which recess not only the throttle section of the throttle duct, which exhibits a throttle effect, but also the throttle inlet, if present, opens. Preferably, the throttle section extends straight from the recess to the deepening.

The deepening makes it possible to ensure that the throttle duct and, if appropriate, its throttle section is arranged close to the longitudinal axis and nevertheless ensures a continuous connection between the control duct and the throttle duct. The deepening also enables the formation of a throttle inlet which is optionally present, preferably extends in the radial direction with respect to the longitudinal axis, and has a short length, which likewise enables simple production of the slide valve body.

Due to the reduced length of the recess and optionally the deepening of the throttle duct relative to the prior art or the throttle section thereof, the throttle duct or the throttle section can be designed to have a constant cross-sectional area or to be conical over its entire length. In a conical embodiment, the taper extends toward the first end side and thus from the control chamber toward the second end side.

It is furthermore possible to round the inlet edge from the control chamber into the throttle duct or into the throttle section thereof in order to improve the flow stability and the flow homogeneity.

Since the throttle inlet has a larger cross-sectional area than the throttle channel or its throttle section, the throttle inlet can be designed with a constant cross-sectional area over its entire length.

If a throttle inlet is present and opens into the deepening, the throttle inlet is preferably designed with a constant cross-sectional area or is designed conically over its entire length. In a conical embodiment, the taper extends toward the recess. It is furthermore possible to round the inlet edge of the throttle inlet towards the high-pressure chamber in order to improve the flow stability and the flow homogeneity. The short length of the throttle inlet enables advantageous manufacturing.

In a plan view of the second front side, the deepened portion preferably has the shape of a rectangle with rounded corners, wherein the long sides preferably extend parallel to a radial line with respect to the longitudinal axis and the short sides perpendicular to the warp line.

The throttle section preferably opens into the deepening adjacent to its radially inner end. Furthermore, this embodiment enables a particularly short length of the throttle inlet.

Preferably, the throttle duct, if appropriate the throttle section thereof and the throttle inlet extend straight and parallel to the longitudinal direction, which enables the throttle duct and the throttle inlet to be produced with only one machine clamping.

Furthermore, the distance between the deepening and the throttle inlet can be designed smaller, since the separating wall between them has only a short length measured in the direction of the longitudinal axis.

Preferably, the throttle inlet extends with its wall at least approximately along the longitudinal axis or adjacent to the longitudinal axis. As a result, the adhesive surface has only a low eccentricity and is at least approximately rotationally symmetrical about the longitudinal axis.

Preferably, the throttle passage and the deepening are arranged diametrically with respect to the throttle inlet. This enables a space-saving design.

Preferably, the second end face has an annular, closed-on-itself orifice sealing bead surrounding the orifice on the side of the throttle inlet and a closed-on-itself ring sealing bead extending along the radially outer wall of the slide valve body. The orifice sealing projection and the ring sealing projection are defined for sealing engagement with a slide valve seat of the control body if the slide valve body is in contact with the control body.

The orifice sealing projection and the ring sealing projection have a low height measured in the longitudinal direction.

Preferably, the orifice sealing bead defines a ring-disk-shaped end-side depression radially on the inside and radially on the outside, into which the throttle channel opens and, if appropriate, from which the throttle channel begins.

By means of this embodiment, the sealing surface between the slide valve body and the control body can be kept low, which results in a further reduction of the adhesion.

Preferably, the front side of the control body forming the slide valve seat is formed flat. This enables a simple production of the control body and ensures a clean sealing of the slide valve seat.

Preferably, a spring element is arranged in the recess, which spring element is supported on the slide valve body in the recess on one side and on the injection valve part on the other side.

The spring element has the task of holding the slide valve body against the control body under balanced pressure.

Preferably, the recess has a shoulder on which the spring element is supported with its end on this side. Thereby, a collision between the spring element and the orifice on the side of the throttle channel and the throttle inlet, which negatively influences the flow, is avoided.

Furthermore, the spring element can be designed smaller than in the prior art, which enables a reduction in the volume of the control chamber and thus a rapid response, in particular during a triggering injection.

Preferably, the depth of the recess measured from the first end side in the direction of the longitudinal axis (which means from the first end side up to the bottom of the recess) is at least half the distance between the first end side and the second end side of the slide valve body. Preferably, the depth is at least approximately three-quarters of the pitch.

This enables, on the one hand, a very short length of the throttle channel and of the throttle inlet, and, on the other hand, a maximum portion accommodating the spring element.

Preferably, the minimum cross-section of the recess is at least five times the sum of the flow cross-sections of the throttle inlet and the throttle channel. The recess thus does not form a throttle constriction for the fuel with respect to the throttle inlet and the throttle channel.

The throttle duct and the control duct are preferably connected to the high-pressure chamber via a throttle inlet formed in the slide valve body, preferably continuously, however at least at the end of the injection process. This supports a very rapid end of the injection process in which fuel can be replenished through the throttle inlet when the control channel is closed.

Preferably, the slide valve body is provided radially outwardly in an end region adjoining the second end side with a circumferential outer taper, which is acted upon by fuel under high pressure. A pressure-acting annulus is thereby created, which results in a pressure directed away from the control body and towards the control chamber.

This supports or in the event of a throttle inlet failure causes the slide valve body to lift off the control body at the end of the injection process.

If a throttle inlet is present, the pressure acting on the second end side increases very rapidly at the end of the injection process when the control channel is closed off, due to the additional flow of fuel. This results in a rapid lifting of the slide valve body from the control body and in a very rapid end of the injection process.

If the throttle inlet is not present and the control channel is closed at the end of the injection process, the slide valve body is lifted from the control body as long as the force of the fuel acting on the second end face, together with the pressure mentioned above, is greater than the force acting on the slide valve body by the fuel in the control chamber and the spring element which is present if necessary. As soon as the slide valve body is lifted from the control body, fuel flows back into the control chamber via the gap and the throttle inlet opening and the throttle channel formed in this way, which results in a rapid pressure rise in the control chamber and a movement of the injection valve part in connection therewith toward the injection valve seat.

The advantage of this variant is that no fuel can flow from the high-pressure chamber into the control channel during the injection process, which means a lower fuel consumption for controlling the injection valve. Furthermore, when the control channel is opened to trigger the injection process, a pressure drop takes place more rapidly in the control chamber, which results in a rapid lifting of the injection valve part from the injection valve seat.

Drawings

The invention is described in more detail by means of embodiments shown in the drawings. Purely schematically shown:

fig. 1 shows a longitudinal section through a fuel injection valve for intermittent injection of fuel into a combustion chamber of an internal combustion engine;

fig. 2 is likewise a longitudinal section and shows a part of the fuel injection valve, which is marked with a rectangle II, in an enlarged manner with respect to fig. 1;

fig. 3 likewise shows a longitudinal section and a section of the fuel injection valve marked there with a rectangle III in an enlarged manner with respect to fig. 2;

fig. 4 shows a longitudinal section through a slide valve body of the fuel injection valve according to fig. 1 to 3;

fig. 5 shows the slide valve body according to fig. 4 in a top view;

fig. 6 shows the slide valve body according to fig. 4 and 5 in a perspective view from above in an inclined manner; and

fig. 7 shows the slide valve body according to fig. 4 to 6 in a perspective view from below in an oblique manner.

Detailed Description

In all figures, the same reference numerals are always used for parts corresponding to each other.

The fuel injection valve 10 for intermittent injection of fuel into the combustion chamber 12 of an internal combustion engine, which is shown in longitudinal section in fig. 1 to 3, has a housing 14, on which a high-pressure inlet 16 is formed on one side and an injection valve seat 18 is formed on the other side. In the interior of the housing 14, a high pressure chamber 20 extends from the high pressure inlet 16 to the injection valve seat 18.

The fuel at very high pressure is supplied to the high pressure chamber 20 through the high pressure inlet 16 in a known manner.

The injection valve member 22, which is embodied as a needle, cooperates with the injection valve seat 18 and is arranged and guided in the housing 14 in a longitudinally movable manner. The closing spring 24 is supported on the injection valve part 22 and exerts a spring force on said injection valve part counter to the direction of the injection valve seat 18.

In the end region of the injection valve part 22 facing away from the injection valve seat, a double-acting control piston 26 is formed on the injection valve seat. The piston face 28 of the control piston facing the injection valve seat 18 defines the high-pressure chamber 20 and is thus acted upon by fuel under high pressure. The control piston 26 defines a control chamber 32 with its end face 30 facing away from the injection valve seat 18.

The control piston 26 is guided with a tight fit 34 in a hollow-cylindrical control sleeve 36, which is rotationally symmetrical about a longitudinal axis 38. Which in the embodiment shown coincides with the longitudinal axis of the housing 14 and the longitudinal axis of the injection valve member 22.

The control sleeve 36 defines the control chamber 32 at Zhou Cexian and the locking spring 24 is supported on the end of the control sleeve facing the injection valve seat.

A cylindrical slide valve body 42 is guided in the control sleeve 36 in a manner such that a tight sliding fit 40, which defines the longitudinal axis 38, is movable in the direction of the longitudinal axis 38.

The slide valve body 42 has a first end 44 facing the control chamber 32 and thus the control piston 26 and a second end 46 opposite the first end and thus facing away from the control piston 26. A throttle passage 48 is provided between the first end side 44 and the second end side 46.

The control body 50 is fixedly arranged with the housing in the housing 14, with its front side 52 facing the slide valve body 42 and in the example shown being embodied flat, forming a slide valve seat 54 which cooperates with the second end side 46 of the slide valve body 42.

The control sleeve 36 rests with its end on the front side 52 of the control body 50, where the locking spring 24 holds the control sleeve against it. In the end region of this side, the control sleeve 36 has at least one channel 56 which is connected to the high-pressure chamber 20.

Extending from the front side 52 through the control body 50 is a control channel 58, which on the side of the control body 58 facing away from the front side 52 can be connected to and disconnected from a low-pressure chamber 62 by means of a pilot valve 60. The narrowest point of the control channel 58 is in the end section of the control channel 58 facing the low-pressure chamber.

In a known manner, fuel flowing into low pressure chamber 62 is directed back to the fuel tank via a fuel return line.

The throttle passage 48 and the control passage 58 are continuously in flow connection with each other.

Furthermore, throttle duct 48 and control duct 58 are continuously connected in flow communication with high-pressure chamber 20 via a throttle inlet 64 formed in slide valve body 42; i.e. in the embodiment shown via the channel 56 of the control sleeve 36.

Furthermore, the slide valve body 42 has a throttle inlet 66 which opens out from the second end face 46 and opens into the control chamber 32. The throttle inlet is closed when the slide valve body 42 is in contact with the control body 50.

If the slide valve body 42 is moved away from the control body 50, a gap 68 is formed between the slide valve body and the control body, which gap is likewise connected to the high-pressure chamber 20 via the channel 56, and the throttle channel 48 and the control channel 58 are additionally connected via the gap and the throttle inlet 66 is connected to the high-pressure chamber 20.

A pocket-shaped recess 70, which is formed rotationally symmetrically with respect to the longitudinal axis 38, starting from the first end 44 is formed in the slide valve body 42. From a bottom 72 of the recess 70, which extends perpendicular to the longitudinal axis 38, the throttle channel 48 extends towards the second end side 46. In addition, the throttle inlet 66 opens into the recess 70 and thus into the control chamber 32 in the region of the base 72.

With additional reference to fig. 4-7, these figures show the spool valve body 42 in different views, which will now be described in more detail.

The throttle section 74 and the throttle inlet 66 of the throttle passage 48 in the embodiment shown are continuously cylindrical in shape and extend parallel to the longitudinal axis 38. The throttle inlet 66 is adjacent to the longitudinal axis 38, while the throttle section 74 extends diametrically opposite, spaced apart from the longitudinal axis 38 by a radial distance.

It is also possible for the throttle section 74 to be formed from the recess 70, preferably conically tapering over the entire length, and/or to round the edges between the base 72 and the throttle section 74.

The throttle section 74 opens into a pocket-shaped recess 76 which belongs to the throttle duct 48 and is removed from the second end side 46 on the slide valve body 42.

The throttle inlet 64, which extends in the radial direction with respect to the longitudinal axis 38, also opens into the pocket-shaped deepening 76.

At the radially outer inlet opening of throttle inlet 64 and diametrically opposite it, a respective tangential chamfer 78 is removed from slide valve body 42, in order to ensure a low-loss inflow of fuel and a symmetrical pressure situation and to enable better machining of throttle inlet 64.

The pocket-shaped deepening 76, which is open over the entire surface toward the second end 46, is formed as a square with rounded edges. The long side 80 extends parallel to a radial line, with the throttle inlet 64 being configured to be centered on the radial line. The short side 82 extends perpendicularly thereto. The radial interior and thus the throttle channel 48 is separated from the throttle inlet 66 by a thin wall over the entire axial length.

Alternatively, it is also possible for the second side to be shaped as a semicircle in plan view.

The second end side 46 has a self-closing, annular orifice sealing bead 86 which surrounds the orifice 84 surrounding the side of the throttle inlet 66. Along a radially outer side surface 88 of the slide valve body 42, the second end side 46 has a ring seal bead 90 which is closed on itself. The ring sealing surfaces on the axially free ends of the orifice sealing projection 86 and the ring sealing projection 90 lie in a common plane which extends perpendicular to the longitudinal axis 38. The orifice sealing projection 86 and the ring sealing projection 90 cooperate with the slide valve seat 54 formed by the front side 52 of the control body 50.

The annular disk-shaped end-side deepening 92 is delimited radially on the inside by the orifice sealing projection 86 and radially on the outside by the annular sealing projection 90. The pocket-shaped deepened portion 76 is opened toward the end-side deepened portion 92 over the entire surface.

The depth of the end-side deepening portion 92 and thus the heights of the orifice sealing projection 86 and the ring sealing projection 90 are small; for example between 0.05mm and 0.20 mm.

As can be seen in particular from fig. 3, 4 to 7, in the illustrated embodiment of the slide valve body 42 in the region of the second end face 46 a continuous connection between the control channel 58 and the throttle channel 48 is ensured, irrespective of the rotational position of the slide valve body 42 relative to the control body 50. Furthermore, the annular sealing surface formed by the orifice sealing bead 86 and the annular sealing bead 90 has a small radial width, which results in a low adhesion between the slide valve body 42 and the control body 50 on the one hand and a good sealing effect against the high-pressure chamber 20 when the slide valve body 42 is in contact with the control body 50 on the other hand.

For the sake of completeness, it is mentioned that in the end region adjoining the second end side 46, the side surface 88, which is close to the end of the side of the slide valve body 42, reaches into the chamfer 78, is formed conically tapering with an external taper 148 in the exemplary embodiment shown. This ensures that in this region there is always fuel under high pressure around the spool valve body 42 and thus symmetrical hydraulic forces act on the spool valve body 42.

This effect is supplemented by the ring recess 94 which is present radially inside on the control sleeve 36 in the end region of this side, see fig. 3, which is connected to the high-pressure chamber 20 via the channel 56.

Because of the pressure-acting annulus of the outer taper 148 having an outer diameter D1 and an inner diameter D2 (see fig. 4), the annulus is loaded with fuel at high pressure. If the spool valve body is in contact with the control body 50, the pressure generated by the fuel under high pressure thereby acts on the spool valve body 42 away from the control body 50 and toward the control chamber 32. Diameter D1 corresponds to the diameter of the tight slip fit 40, while diameter D2 corresponds to the outer diameter of the ring seal boss 90 and thus the slide valve seat 54.

The recess 70 of the slide valve body 42, which has a circular cross section over its entire length, extends in the direction of the longitudinal axis 38 and extends over a length L of three-quarters of the distance a between the first end side 44 and the second end side 46, measured from the first end side 44. Between the first end side 44 and the second end side 46, for example centrally, the recess 70 has a shoulder 96, which narrows the cross section and on which a spring element 98 is supported as shown in fig. 1 to 3.

The recess has a conical taper 100, measured from the first end side 44, at about one third of the distance a between the first end side 44 and the second end side 46. This ensures that the spring element 98 is held firmly with its end region on this side between the conical taper 100 and the shoulder 96, but does not rest on the slide valve body 42 between the first end side 44 and the conical taper 100.

In the illustrated embodiment, the smallest cross-section of the recess 70 in the cylindrical section between the shoulder 96 and the bottom 72 of the recess 70 is approximately eight times greater than the sum of the cross-sections of the throttle inlet 66 and the throttle passage 48. In the region from the first end side 44 up to the shoulder 96, this ratio is greater even with the insertion of the spring element 98. Thus, the recess 70 does not have a throttling effect on fuel flowing through the throttle inlet 66 and the throttle passage 48.

The embodiment of the first end 44 can be seen particularly well from fig. 4 and 7. On the first flat end 44, six trapezoidal stop projections 104 are formed, which are distributed uniformly in the circumferential direction and protrude in the axial direction and are separated from one another by end deepening 102. The stop projection 104 is defined for cooperation with a stop shoulder 106 (see fig. 3) formed on the control sleeve 36 on the inner side thereof. If the slide valve body is to be moved away from the stop shoulder 106 in the direction of the control body 50 due to a pressure situation, the slide valve body 42 is formed on the first end 44 in such a way that a minimum adhesion between the stop shoulder 106 and the slide valve body 42 is ensured.

As shown in fig. 2 and 3, the end face 30 of the injection valve part 80 facing the slide valve body 42 has a protruding stub shaft 108 centrally, which is surrounded by the end region of the spring element 98 on this side. Thereby, the spring element 98 is also held centrally on this side.

The spring force generated by the spring element 98 is small relative to the spring force of the locking spring 24, however, it is ensured that the slide valve body 42 rests against the control body 50 on both sides thereof under hydraulic pressure equalization.

The slide valve body 42 can thereby reciprocate between the stop shoulder 106 and the control body 50 through a stroke marked H2 in fig. 3. Fig. 3 shows that slide valve body 42 rests against stop shoulder 106 and thus lifts maximum travel H2 from control body 50.

In fig. 3, H1 represents the maximum stroke of injection valve member 22. In the position shown in fig. 3, injection valve part 22 rests against injection valve seat 18. However, this maximum travel H1 is only possible if the slide valve body 42 is in contact with the control body 50.

If control piston 26 of injection valve member 22 is resting against valve body 42 during injection, stop tab 104 likewise ensures minimal adhesion between valve body 42 and injection valve member 22.

The close fit 34 for the control piston 26 has a tolerance of 2 μm to 10 μm and the slip fit 40 for the slip valve body 42 also has a tolerance of 2 μm to 10 μm. The travel H2 of spool body 42 is about 0.04mm to about 0.10mm and the travel H1 of injection valve member 22 is about 0.30mm to about 0.50mm, which is related to the size of combustion chamber 12 of the internal combustion engine.

Also depending on the size of the combustion chamber 12 of the internal combustion engine, the diameter of the throttle inlet 66 is, for example, about 0.30mm to about 0.80mm, the diameter of the throttle section 74 is about 0.10mm to about 0.25mm, the diameter of the throttle inlet 64 is about 0.10mm to about 0.25mm, and the diameter of the narrowest portion of the control passage is about 0.20mm to about 0.45mm.

The remaining components of the fuel injection valve 10 shown in fig. 1 to 3 are described below.

The housing 14 has a substantially cylindrical storage body 110, on the end face of which a high-pressure inlet 16 is formed. A pocket-like opening extends from the high-pressure inlet 16 to an end region of the storage body 110 facing away from the high-pressure inlet, said opening forming a separate storage space 112.

From the high-pressure inlet 16, a truncated cone-shaped holder 114 with a cup-shaped filter 116 for the fuel is inserted into the pocket-shaped bore. The holder 114 can also be designed as a valve holder with a non-return valve, as is known from WO 2014/131497 A1.

The pocket-like openings forming the separate storage chambers 112 from the bottom extend as far as the end face of the storage body 110 on this side, the sections of the fuel channel 118 extending obliquely outward in the radial direction with respect to the longitudinal axis 38.

With respect to this section of the fuel channel 118, diametrically opposite with respect to the longitudinal axis 38, a bore 120 extends in the storage body from the end face of this side of the storage body 110 to an electrical control connection 122. In the bore 120, an electrical control wire 126 for operating the pilot valve 60 extends from the control link 122 to a link plug 124.

The generally known electromagnetic actuator 128 is arranged in an intermediate body 130 of the housing 14, which is sealingly attached to the storage body 110 on the side facing away from the high-pressure inlet 16. The coil of the actuator 128 is electrically connected to the connection terminal plug 124.

A second section of the fuel flow passage 118 extends through the intermediate body 130 alongside the actuator 128 parallel to the longitudinal axis 38.

The pilot valve 60 has a tappet 132 (fig. 2 and 3) that is manipulated by the actuator 128 to connect or disconnect the control passage 58 from the low pressure chamber 62. For completeness, it is mentioned that the rotational position of the intermediate body 130 relative to the storage body 110 is specified by means of a positioning pin.

The nozzle body 134, on which the injection valve seat 18 is formed, rests sealingly against the end face of the intermediate body 130 facing away from the storage body 110.

The lock nut 136 is supported on the outer shoulder of the nozzle body 134, itself accommodates the intermediate body 130 and is screwed with its internal thread onto the external thread of the storage body 110, so that the nozzle body 134 is tightly held against the intermediate body 130 and said intermediate body is tightly held against the storage body 110.

In the nozzle body 134, the third section of the fuel flow channel 118 extends obliquely from the second section in the intermediate body 130 in the radial direction toward the inside into a control recess 138, which is formed rotationally symmetrically with respect to the longitudinal axis 38 and extends from the end face of the nozzle body 134 facing the intermediate body 130 up to the injection valve seat 18.

The control body 50, which rests closely on the end face on the intermediate body 130, is located in the end region of the control recess 138 facing the intermediate body 130, the rotational position of which is determined by means of a positioning pin 140, which is inserted into the control body 50 on one side and engages into the intermediate body 130 on the other side.

Another dowel pin 142 is inserted into the nozzle body 134 on one side and into the intermediate body 130 on the other side to fix its opposite rotational position.

The control recess 138, the fuel flow passage 118 and the separate storage chamber 112 form the high-pressure chamber 20.

In the guide section of the nozzle body 134 facing the injection valve seat 18, the control recess 138 is cylindrical. On the guide section, the injection valve members 122 located in the control recesses 138 are guided in a freely movable manner in the direction of the longitudinal axis 38 with guide projections 144 extending in the direction of the longitudinal axis 38 at a distance from one another in the circumferential direction. Between the guide projections 144, the fuel can reach the injection valve seat 18 virtually unimpeded.

Downstream of the injection valve seat 18, which is embodied in the form of a cone, a nozzle channel 146 is embodied in a known manner on the nozzle body 134, through which fuel is injected into the combustion chamber 12 during injection.

In the middle section of the control recess 138, the control sleeve 136 is held against the control body 50 by the locking spring 24, wherein the locking spring 24 is supported on the other side on the injection valve part 22.

As also described above, not only the double acting control piston 26 but also a slide valve body 42 guided with a tight sliding fit 40 on the control sleeve 36 between the control piston and the control body 50 is arranged in the control sleeve 36.

The fuel injection valve 10 functions as follows:

in a stationary state, the pilot valve 60 disconnects the control passage 58 from the low pressure chamber 62. The slide valve body 42 rests with its second end face 46 tightly against the front face 52 of the control body 50. The fuel under high pressure is located in the control chamber 32, in the control channel 58, in the throttle inlet 66, in the throttle channel 48 and in the end-side deepening 92, wherein the injection valve part 22 rests on the injection valve seat 18.

To trigger the injection event, actuator 128 is activated, whereby pilot valve 60 connects control passage 58 with low-pressure chamber 62 by lifting tappet 132 from control body 50. Because the narrowest hydraulic cross-sectional area of control passage 58 is greater than the flow cross-sectional area of throttle inlet 64, fuel flows from control chamber 32 to low-pressure chamber 62 through throttle passage 48, which results in a rapid pressure drop in control chamber 32 and an associated lifting of injection valve member 22 from injection valve seat 18. As soon as injection valve member 22 is lifted from injection valve seat 18, fuel under high pressure is injected into combustion chamber 12 through nozzle passage 146.

At the end of the injection process, actuator 128 is deactivated, so that tappet 132 of pilot valve 60 again rests on control body 50 and thus closes control channel 58. Since no more fuel can now flow out into low-pressure chamber 62, however, the fuel flows back through throttle inlet 64, the pressure of the fuel increases in control channel 58, in deepening 76 and thus in end-side deepening 92, faster than in control chamber 32, in which the fuel can flow back through throttle section 74 of throttle channel 48 less quickly. The increased pressure of the fuel on the second end side 46 relative to the deeper pressure on the first end side 44, along with the pressure acting on the annulus, results in: the spool body 42 is quickly lifted from the control body 50 and thereby forms a gap 68 therebetween. This results in a more rapid pressure increase in the control chamber 32 via the throttle inlet 66, which results in the injection valve part 22, which is supported by the force of the locking spring 24, being moved against the direction of the injection valve seat 18 and resting against said injection valve seat, which results in the end of the injection process.

As soon as the pressure forces on the first end 44 and the second end 46 of the slide valve body 42 are approximately equalized, the slide valve body 42 moves again, again against the control body 50 under the action of the spring element 98.

The fuel injection valve and in particular the slide valve body 42 are otherwise identical to those described and shown in the figures, if the throttle inlet 64 is not present.

The function at the introduction of the injection process is the same as described above, with the exception that no fuel can flow back from the high-pressure chamber 20 and thus the pressure reduction in the control chamber 32 takes place slightly more rapidly.

If the control channel 58 is closed at the end of the injection process, the slide valve body 42 is lifted from the control body 50, as long as the force of the fuel acting on the second end face 46, together with the pressure acting on the annular surface, which is mentioned again above, is greater than the force exerted by the fuel on the slide valve body 42 in the control chamber 32 and, if appropriate, in the spring element 98. As soon as the slide valve body 42 is lifted from the control body 50, fuel flows from the high-pressure chamber via the gap 68 and the throttle inlet 66 thus formed and the throttle duct 48 into the control chamber 32, which results in a rapid pressure increase in the control chamber 32 and an associated movement of the injection valve part 22 to the injection valve seat 18.

Claims

1. A fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine, the fuel injection valve comprising: a housing (14) having a high pressure inlet (16) for fuel under high pressure and an injection valve seat (18); a high pressure chamber (20) provided in the housing (14) and extending from the high pressure inlet (16) to the injection valve seat (18); an injection valve part (22) for interaction with the injection valve seat (18), which is arranged in the housing (14) in a longitudinally movable manner and is spring-loaded against the direction of the injection valve seat (18); a double-acting control piston (26) formed on the injection valve part (22), which defines a high-pressure chamber (20) on one side and a control chamber (32) on the other side; a slide valve body (42) guided in a sliding fit (40) defining a longitudinal axis (38), said slide valve body having a first end side (44) facing the control chamber (32), a second end side (46) opposite the first end side, and a throttle channel (48) arranged between the first end side (44) and the second end side (46); a control body (50) which forms, with its front side (52) facing the slide valve body (42), a slide valve seat (54) which cooperates with a second end side (46) of the slide valve body (42) and which has a throttle inlet (66) which issues from the front side (52) and opens into the control chamber (32) and which is connected to the low-pressure chamber (62) by means of a pilot valve (60) and which can be disconnected from the low-pressure chamber, wherein the throttle channel (48) and the control channel (58) are connected in a flow manner to the high-pressure chamber (20) via a gap (68) which is formed when the slide valve body (42) is lifted from the slide valve seat (54), and wherein the slide valve body (42) has a throttle inlet (66) which issues from the second end side (46) and opens into the control chamber (32) and which is closed when the slide valve body (42) is lifted from the control body (50) and is connected to the high-pressure chamber (20) when the slide valve body (42) is lifted from the control body (50), characterized in that the slide valve body (42) has a longitudinal recess (70) extending from the first end (46) and at least approximately from the second end (46), and the throttle inlet (66) opens into the recess (70).

2. The fuel injection valve according to claim 1, characterized in that the throttle duct (48) has a deepening (76) formed on the slide valve body (42) that opens out toward the second end face (46), into which deepening a throttle section (74) of the throttle duct (48) opens.

3. A fuel injection valve according to claim 2, wherein the deepened portion (76) is pocket-shaped.

4. A fuel injection valve according to one of claims 1 to 3, characterized in that the throttle inlet (66) extends at least approximately parallel to the longitudinal axis (38) and at least approximately adjacent to the longitudinal axis (38).

5. A fuel injection valve according to one of claims 1 to 3, characterized in that the second end face (46) has an annular orifice sealing bead (86) and a ring sealing bead (90) extending along a radially outer side surface (88) of the slide valve body (42), wherein the orifice sealing bead (86) and the ring sealing bead (90) are defined for cooperation with the slide valve seat (54), and the orifice sealing bead (86) defines a ring-disk-shaped end-face depression (92) radially inwardly and radially outwardly of the ring sealing bead (90), into which the throttle channel (48) opens and which opens out into the control body (50).

6. A fuel injection valve according to claim 5, wherein the orifice sealing protrusion (86) directly surrounds the orifice (84) on the side of the throttle inlet (66).

7. The fuel injection valve according to claim 5, wherein the end-side deepened portion (92) is open toward the entire surface of the control body (50).

8. The fuel injection valve according to claim 2, wherein the deepened portion (76) is open toward the end-side deepened portion (92).

9. The fuel injection valve according to claim 8, wherein the deepened portion (76) is opened toward the end-side deepened portion (92) over the entire surface.

10. A fuel injection valve according to one of claims 1 to 3, characterized in that a spring element (98) is arranged in the recess (70), which spring element is supported on the slide valve body (42) in the recess (70) on one side and on the injection valve part (22) on the other side.

11. A fuel injection valve according to one of claims 1 to 3, characterized in that the length (L) of the recess (70) measured from the first end side (44) in the direction of the longitudinal axis (38) is at least half the distance (a) between the first end side (44) and the second end side (46).

12. The fuel injection valve according to claim 11, characterized in that the length (L) of the recess (70) measured from the first end side (44) in the direction of the longitudinal axis (38) is at least approximately three-quarters of the distance (a) between the first end side (44) and the second end side (46).

13. A fuel injection valve according to any one of claims 1 to 3, wherein the minimum cross-sectional area of the recess (70) is at least five times the sum of the minimum cross-sectional areas of the throttle inlet (66) and the throttle passage (48).

14. A fuel injection valve according to one of claims 1 to 3, characterized in that the throttle channel (48) and the control channel (58) are connected in flow communication with the high-pressure chamber (20) via a throttle inlet (64) formed in the slide valve body (42).

15. The fuel injection valve according to claim 14, characterized in that the throttle duct (48) and the control duct (58) are continuously connected in flow communication with the high-pressure chamber (20) via a throttle inlet (64) formed in the slide valve body (42).

16. A fuel injection valve according to claim 14, wherein the throttle inlet (64) opens into the deepening (76).

17. A fuel injection valve according to one of claims 1 to 3, characterized in that the slide valve body (42) has a circumferential outer taper (148) radially outside in an end section facing the second end side (46), which outer taper is acted upon by fuel under high pressure.