CN114761681A

CN114761681A - Fuel injection valve for an internal combustion engine having a slide valve

Info

Publication number: CN114761681A
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: 2022-07-15
Anticipated expiration: 2040-12-01
Also published as: CN114761681B; WO2021110663A1; JP2023504727A; EP4069963A1

Abstract

A fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine has a spool body (42) guided in a sliding fit (40). A pocket-shaped recess (70) is formed in the spool body, which recess is aligned with the longitudinal axis (38) and extends from a first end (44) facing the control chamber (32). From the bottom (72) of the recess, both the throttle inlet (66) and the throttle channel (48) are guided to the second end face (46). The throttle channel (48) can be connected to the high-pressure chamber (20) via a throttle inlet (64) which is also formed on the slide valve body (42). If the slide valve body (42) is in contact with the control body (50), the throttle inlet (66) is closed and the throttle channel (48) and the control channel (58) are connected to one another. However, if the slide valve body (42) is lifted from the control body (50) at the end of the injection process, a gap (68) is formed which releases the throttle inlet (66), as a result of which fuel can flow from the high-pressure chamber (20) into the control chamber (32) via the throttle inlet (66) and the throttle channel (48) in a complementary manner.

Description

Fuel injection valve for an internal combustion engine having a slide valve

Technical Field

The present invention relates to a fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine according to the preamble of claim 1.

Background

A fuel injection valve of this type is known from document EP 1273791 a 2. The fuel injection valve shown in fig. 6 of this document has a spool body which is guided in a hollow cylindrical sleeve with a tight sliding fit and which has a first end side facing the control chamber and a second end side opposite the first end side. The throttle inlet extends from the second end side to the first end side, wherein the throttle inlet is spaced apart from the second end side and further apart from the first end side, the throttle inlet having a throttle constriction. Furthermore, the throttle channel, which has a further throttle constriction at a correspondingly identical distance from the throttle inlet, extends from the first end side to the second end side. A throttle inlet extending in the radial direction is formed on the slide valve body, said throttle inlet opening into the throttle channel. The front side of the control body, which faces the slide valve body, forms a slide valve seat which interacts with the second end side of the slide valve body. The control body has a control channel which starts from the front side and is continuously in flow connection with the throttle channel and can be connected to the low-pressure chamber by means of a pilot valve and can be disconnected from the low-pressure chamber. The throttle channel and the control channel are continuously in flow connection with the high-pressure chamber via the throttle inlet. When the slide valve body is lifted off the slide valve seat, a gap is formed, via which the throttle channel and the control channel are additionally fluidically connected, and the throttle inlet is fluidically connected to the high-pressure chamber.

The eccentrically formed adhesion surface between the second end of the slide valve body and the front of the control body causes a delay in the response of the fuel injection valve in order to terminate the injection. Furthermore, the production is complicated, since the slide valve body must be designed precisely and, in particular, the throttle inlet, the throttle channel and the throttle slot of the throttle inlet must be produced with very small tolerances.

Disclosure of Invention

The object of the present invention is therefore to further develop a fuel injection valve of the same type such that the delay in response is minimized while the production is simple.

This object is achieved in a fuel injection valve of the generic type by the features of the characterizing portion of claim 1.

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 an injection 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 being acted upon by a force of a locking spring against the direction of the injection valve seat and being intended for interacting with the injection valve seat. In the rest state, the injection valve part bears against the injection valve seat and thus prevents fuel from being injected from the high-pressure chamber into the combustion chamber of the internal combustion engine in a known manner. To trigger an 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 member then again bears against the injection valve seat.

A double-acting control piston, 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, is formed on the injection valve part.

Preferably, the control chamber is delimited circumferentially by a preferably hollow-cylindrical sleeve, on which the control piston is guided with a tight sliding fit and on which the blocking spring is supported, which is supported on the other side on the injection valve part and which loads its spring force towards the injection valve seat.

Instead of being formed on the sleeve, on the housing itself or on a differently formed component arranged in the housing, the control piston can be guided in a sliding manner, wherein the housing or the component delimits the control chamber on the circumferential side.

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

Preferably, the slide valve body has an outer wall which is at least approximately rotationally symmetrical with respect to the longitudinal axis.

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

Furthermore, a control body is fixedly arranged in the housing relative to the housing, said control body forming 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.

Preferably, the sleeve is held against the control body by means of a force acting thereon by means of a locking spring.

Furthermore, the spool valve body has a throttle channel arranged between a first end side and a second end side.

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

The preferably present 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, at least at the end of the injection process, preferably continuously, to the high-pressure chamber via a throttle inlet formed on the slide valve body.

The slide valve body also has a throttle inlet opening out of the second end side 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 with the high-pressure chamber. The gap is closed when the slide valve body is in contact with the control body.

In order to connect this 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.

The throttle channel, which extends from the recess, preferably from its bottom, which is preferably flat and extends perpendicular to the longitudinal axis, exits toward the second end side, and the throttle inlet from the second end side opens into the recess, preferably in the region of the bottom of the recess.

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

The recess enables both the throttling channel and the throttling inlet to be formed shorter than is known from the prior art, which simplifies their manufacture.

Furthermore, the embodiment of the slide valve body according to the invention makes it possible to form the throttle channel and the throttle inlet closely next to each other and in the vicinity of the longitudinal axis. This makes it possible to avoid adhesive surfaces between the control body and the slide valve body with a significant eccentricity with respect to the longitudinal axis; the adhesive surface has a smaller eccentricity compared to 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 behavior 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 equalizes the operating behavior of fuel injection valves of the same design.

Preferably, the throttle channel has a preferably pocket-shaped deepening formed on the slide valve body and open to the second end, into which deepening both the throttle section of the throttle channel, which exhibits the throttling effect, and (if present) the throttle inlet open. Preferably, the throttle section extends linearly from the recess to the deepening.

This deepening makes it possible to ensure that the throttle channel and, if appropriate, its throttle section are arranged close to one another in the longitudinal axis and nevertheless ensure a continuous connection between the control channel and the throttle channel. Furthermore, the deepening makes it possible to form a throttle inlet, which is optionally present and preferably extends in the radial direction with respect to the longitudinal axis, with a short length, which also supports simple production of the spool valve body.

Due to the reduced length of the recess and, if appropriate, the deepening of the throttle channel compared to the prior art or the throttle section thereof, it is possible to design the throttle channel or the throttle section over its entire length with a constant cross-sectional area or with a conical design. In the case of a conical design, the tapering extends toward the first end side and thus from the control chamber to the second end side.

Furthermore, it is possible to round the inlet edge from the control chamber into the throttle channel or its throttle section in order to improve flow stability and flow homogeneity.

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

If a throttle inlet is present and opens into the deepened portion, the throttle inlet is preferably designed over its entire length with a constant cross-sectional area or is designed to be conical. In a conical embodiment, the tapering extends towards the recess. Furthermore, it is possible to round the inlet edge of the throttle opening facing the high-pressure chamber in order to improve the flow stability and the flow uniformity. The short length of the throttle inlet enables advantageous manufacture.

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 run parallel to a radial line with respect to the longitudinal axis and the short sides run perpendicular to the warp line.

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

Preferably, the throttle channel, if appropriate its throttle section, and the throttle inlet extend linearly and parallel to the longitudinal direction, which makes it possible to produce the throttle channel and the throttle inlet in only one machine clamping.

Furthermore, the distance between the deepening and the throttle inlet can be made smaller, since the partition 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 or adjacent to the longitudinal axis. This results in a configuration of the adhesive surface which is only low in eccentricity and at least approximately rotationally symmetrical with respect to the longitudinal axis.

Preferably, the throttle channel and the deepening are diametrically arranged about the throttle inlet. This enables a space-saving construction solution.

Preferably, the second end side has an annular, closed-off nozzle sealing projection surrounding the nozzle on the side of the throttle inlet and a closed-off ring sealing projection extending along the radially outer wall of the slide valve body. The orifice sealing projection and the ring sealing projection are intended to cooperate sealingly with a slide valve seat of the control body if said slide valve body abuts against the control body.

The orifice seal protrusion and the ring seal protrusion have a low height measured in the longitudinal direction.

Preferably, the bore sealing projection defines a ring-disk-shaped end-side deepening radially on the inside and the ring sealing projection defines a ring-disk-shaped end-side deepening radially on the outside, into which the throttle channel opens and from which the deepening emerges, if appropriate.

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

Preferably, the front side of the control body, which forms 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 provided 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 spool valve body against the control body in the case of a balanced pressure.

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

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 behavior, in particular during the triggering of an injection.

Preferably, the depth of the recess, measured in the direction of the longitudinal axis from the first end side (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 spool 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 the throttle inlet, and, on the other hand, a maximum portion of the spring element to be accommodated.

Preferably, the smallest 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.

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

Preferably, the slide valve body is provided with a circumferential outer taper radially on the outside in the end region adjacent to the second end side, which outer taper is acted on by the fuel under high pressure. This creates a pressure-active annulus, which leads to a pressure that is directed away from the control body and toward the control chamber.

This supports or, in the event of a throttle inlet failure, causes the slide valve body to lift off from 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 due to the additional flow of fuel when the control channel is closed at the end of the injection process. This results in a rapid lifting of the slide valve body from the control body and a very rapid end of the injection process.

If no throttle inlet is 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 side, together with the above-mentioned pressure, is greater than the force acting on the slide valve body by the fuel in the control chamber and the optionally present spring element. As soon as the slide valve body is lifted off the control body, the fuel flows back into the control chamber via the gap and the throttle inlet and the throttle channel formed in this way, which leads to a rapid pressure increase in the control chamber and the movement of the injection valve part in conjunction 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 an injection process, a pressure drop occurs more rapidly in the control chamber, which leads to a rapid lifting of the injection valve member from the injection valve seat.

Drawings

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

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

fig. 2 likewise shows a detail of the fuel injection valve, which detail is marked there with a rectangle II, in a longitudinal section and enlarged in relation to fig. 1;

fig. 3 likewise shows a detail of the fuel injection valve, which is marked there with a rectangle III, in longitudinal section and enlarged in relation to fig. 2;

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

fig. 5 shows a 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 at an angle; and

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

Detailed Description

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

A fuel injection valve 10 for the intermittent injection of fuel into a 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.

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

An injection valve part 22, which is designed in the form of a needle and is arranged and guided in a longitudinally movable manner in the housing 14, interacts with the injection valve seat 18. A locking spring 24 is supported on the injection valve part 22 and loads it with a spring force against 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 surface 28 of the control piston facing the injection valve seat 18 delimits the high-pressure chamber 20 and is therefore charged with fuel at high pressure. The control piston 26 delimits with its end face 30 facing away from the injection valve seat 18 a control chamber 32.

The control piston 26 is guided in a sliding manner with a tight fit 34 in a hollow-cylindrical control sleeve 36 which is designed to be 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 delimits the control chamber 32 on the peripheral side and the blocking spring 24 is supported on its end facing the injection valve seat.

A cylindrical spool valve body 42 is guided movably in the direction of the longitudinal axis 38 in a tight sliding fit 40 defining the longitudinal axis 38 in the control sleeve 36.

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

A control body 50 is located in the housing 14 in a fixed arrangement with the housing, said control body forming with its front side 52 facing the slide valve body 42 and configured flat in the example shown a slide valve seat 54 which interacts with the second end side 46 of the slide valve body 42.

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

A control channel 58 extends from the front side 52 through the control body 50, said control channel being connectable to and disconnectable from a low-pressure chamber 62 on the side of the control body 58 facing away from the front side 52 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, the fuel flowing into the low-pressure chamber 62 is returned to the fuel tank via a fuel return line.

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

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

Furthermore, the spool valve body 42 has a throttle inlet 66 which opens out from the second end side 46 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 duct 56, and the throttle duct 48 and the control duct 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 from the first end side 44 and is rotationally symmetrical about the longitudinal axis 38, is formed on the spool body 42. From a bottom 72 of the recess 70, which extends perpendicularly to the longitudinal axis 38, the throttle channel 48 extends towards the second end side 46. Furthermore, the throttle inlet 66 opens into the recess 70 in the region of the bottom 72 and thus into the control chamber 32.

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

The throttle section 74 of the throttle channel 48 and the throttle inlet 66 continuously have a cylindrical shape in the illustrated embodiment and extend parallel to the longitudinal axis 38. The throttle inlet 66 is adjacent the longitudinal axis 38, and the throttle section 74 extends diametrically opposite and spaced a radial distance from the longitudinal axis 38.

It is also possible for the throttle section 74 to be tapered, preferably over its entire length, from the recess 70 and/or for the edges between the base 72 and the throttle section 74 to be rounded.

The throttle section 74 opens into a pocket-shaped deepened portion 76, which belongs to the throttle channel 48 and is removed from the second end side 46 at 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 deepened portion 76.

At the radially outer inlet openings of the throttle inlet 64 and diametrically opposite the latter, in each case one chamfer 78 running in the tangential direction is removed from the 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 the throttle inlet 64.

The pocket-shaped deepening 76, which is open over the entire surface toward the second end side 46, is formed as a square with rounded edges. The long side 80 extends parallel to the radial line, to which the throttle inlet 64 is formed. The short side 82 extends perpendicularly thereto. Radially inward and thus the throttle passage 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 in a semicircular manner in plan view.

The second end side 46 has a closed-off, annular nozzle sealing bead 86 which is surrounded by a nozzle 84 surrounding the side of the throttle inlet 66. Along a radially outer lateral surface 88 of the slide valve body 42, the second end side 46 has a ring-shaped sealing bead 90 which is closed on itself. The ring sealing surfaces on the axial free ends of the nozzle sealing projection 86 and the ring sealing projection 90 lie in a common plane which extends perpendicularly 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 ring-disk-shaped end-side deepening 92 is radially inwardly delimited by the spout sealing bead 86 and radially outwardly delimited by the ring sealing bead 90. The pocket-shaped deepened portion 76 is open over the entire surface toward the end-side deepened portion 92.

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

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

For the sake of completeness, it is mentioned that in the end region adjoining the second end side 46, the side surface 88 is configured conically tapering, in the illustrated embodiment, close to the end of this side of the slide valve body 42, up to the point in the chamfer 78, with an outer taper 148. This ensures that fuel under high pressure is always present in this region around the spool valve body 42 and therefore symmetrical hydraulic forces act on the spool valve body 42.

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

Due to the outer taper 148 there is a pressure-acting annulus with an outer diameter D1 and an inner diameter D2 (see fig. 4) which is loaded with fuel at high pressure. If the slide valve body bears against the control body 50, the pressure generated by the fuel at high pressure acts on the slide valve body 42 away from the control body 50 and toward the control chamber 32. Diameter D1 corresponds to the diameter of the close sliding fit 40, while diameter D2 corresponds to the outer diameter of the ring seal protrusion 90 and thus the spool 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 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 in 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 approximately one third of the distance a between the first end side 44 and the second end side 46. This ensures that the end region of the spring element 98 is held firmly between the conical taper 100 and the shoulder 96, but the spring element does not come to bear against the spool valve body 42 between the first end side 44 and the conical taper 100.

In the illustrated embodiment, the minimum cross-section of the recess 70 in the cylindrical section between the shoulder 96 and the bottom 72 of the recess 70 is about 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 even greater even with the insertion of the spring element 98. Thus, the recess 70 does not have a throttling effect on the fuel flowing through the throttle inlet 66 and the throttle passage 48.

The form of the first end side 44 can be seen particularly well in fig. 4 and 7. Six trapezoidal stop projections 104, which project in the axial direction and are distributed uniformly in the circumferential direction and are separated from one another by end-side deepening 102, are formed on the otherwise flat first end side 44. The stop projection 104 is intended to interact with a stop shoulder 106 (see fig. 3) formed on the control sleeve 36 on its inner side. If, due to pressure conditions, the slide valve body is intended to be moved away from the stop shoulder 106 in the direction of the control body 50, the slide valve body 42 is formed on the first end side 44 in such a way that a minimum adhesion force 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 centrally a projecting stub shaft 108, which is surrounded by the end region of this side of the spring element 98. 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 blocking spring 24, however, it is ensured that the slide valve body bears against the control body 50 on both sides of the slide valve body 42 in the case of a hydraulic pressure compensation.

Thereby, the spool valve body 42 can be reciprocated between the stop shoulder 106 and the control body 50 by a stroke marked H2 in fig. 3. Fig. 3 shows that the spool valve body 42 bears against the stop shoulder 106 and is therefore lifted by a maximum stroke H2 from the control body 50.

In fig. 3, the maximum stroke of the injection valve member 22 is denoted by H1. In the position shown in fig. 3, the injection valve part 22 rests against the injection valve seat 18. However, this maximum stroke H1 is only possible when the spool valve body 42 bears against the control body 50.

The stop projection 104 likewise ensures minimal adhesion between the slide valve body 42 and the injection valve member 22 if the control piston 26 of the injection valve member 22 abuts against the slide valve body 42 during the injection process.

The close-fitting portion 34 for the control piston 26 has a tolerance of 2 μm to 10 μm, and the slide-fitting portion 40 for the slide valve body 42 likewise has a tolerance of 2 μm to 10 μm. The stroke H2 of the slide valve body 42 is about 0.04mm to about 0.10mm, while the stroke H1 of the injection valve member 22 is about 0.30mm to about 0.50mm, which is related to the size of the combustion chamber 12 of the internal combustion engine.

Also in relation to 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 point of the control passage is about 0.20mm to about 0.45 mm.

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 which a high-pressure inlet 16 is formed on the end face. A pocket-like bore extends from the high-pressure inlet 16 to the end region of the storage body 110 facing away from the high-pressure inlet, said bore forming a separate storage chamber 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 hole. The holder 114 can also be designed as a valve holder with a check valve, as is known from document WO 2014/131497 a 1.

The pocket-like bore, which forms the separate storage chamber 112 from the bottom, extends as far as the end face of this side of the storage body 110, the section of the fuel channel 118 extending outwards in the radial direction at an angle 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 side of the storage body 110 to an electrical control connection 122. In the bore 120, an electrical control line 126 for actuating the pilot valve 60 extends from the control connection 122 as far as the connection plug 124.

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

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

Pilot valve 60 has a tappet 132 (fig. 2 and 3) that is actuated by actuator 128 to connect or disconnect control passage 58 from low pressure chamber 62. For the sake of completeness, it is mentioned that the rotational position of the central body 130 relative to the storage body 110 is defined by means of positioning pins.

The nozzle body 134, on which the injection valve seat 18 is formed, rests in a sealing manner on the end face of the central body 130 facing away from the storage body 110.

The union nut 136 is supported on an outer shoulder of the nozzle body 134, receives the intermediate body 130 itself and is screwed with its inner thread onto the outer thread of the storage body 110, so that the nozzle body 134 bears tightly against the intermediate body 130 and said intermediate body bears tightly against the storage body 110.

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

The control body 50, which bears tightly against the central body 130 at its end face, is located in the end region of the control recess 138 facing the central 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 central body 130 on the other side.

A further detent pin 142 engages on one side into the nozzle body 134 and on the other side into the intermediate body 130 in order to fix the rotational position thereof on the opposite side.

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 in shape. On the guide section, the injection valve parts 122 located in the control recess 138 are guided freely movably 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 conical injection valve seat 18, a nozzle channel 146 is formed in the nozzle body 134 in a known manner and method, through which fuel is injected into the combustion chamber 12 during the injection process.

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

As described above again, both the double-acting control piston 26 and the slide valve body 42, which is guided with a tight sliding fit 40 on the control sleeve 36 between the control piston and the control body 50, are arranged in the control sleeve 36.

The fuel injection valve 10 functions as follows:

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

To trigger the injection process, actuator 128 is activated, as a result of which pilot valve 60 connects control channel 58 to low-pressure chamber 62 by lifting tappet 132 from control body 50. Since the narrowest hydraulic cross-sectional area of control channel 58 is greater than the flow cross-sectional area of throttle inlet 64, fuel flows from control chamber 32 through throttle channel 48 to low-pressure chamber 62, which results in a rapid pressure drop in control chamber 32 and 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 at high pressure is injected into combustion chamber 12 through nozzle channel 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 thereby closes control channel 58. Since no more fuel can now flow out into the low-pressure space 62, however, the fuel can be replenished via the throttle inlet 64, the pressure of the fuel in the control channel 58 increases, faster in the deepened portion 76 and thus in the end-side deepened portion 92 than in the control chamber 32, in which the fuel can be replenished less quickly via the throttle section 74 of the throttle channel 48. The increased pressure of the fuel on the second end side 46 relative to the deeper pressure on the first end side 44 in conjunction with the pressure acting on the annulus results in: spool valve body 42 is quickly lifted from control body 50 and thereby forms gap 68 therebetween. This leads via the throttle inlet 66 to a more rapid pressure increase in the control chamber 32, which leads to the injection valve member 22, which is supported by the force of the blocking spring 24, moving against the direction of the injection valve seat 18 and resting against said seat, which leads to the end of the injection process.

As long as the pressures on the first end side 44 and the second end side 46 of the spool valve body 42 are approximately balanced, the spool valve body 42 moves again, again in contact with 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 constructed the same as described and shown in the drawings if the throttle inlet 64 is not present.

The functional manner in the introduction of an injection event is the same as described above, with the exception that no fuel can be replenished from high-pressure chamber 20 and therefore the pressure reduction in control chamber 32 takes place somewhat more quickly.

If the control channel 58 is closed at the end of the injection process, the spool valve body 42 is lifted from the control body 50, as long as the force of the fuel acting on the second end side 46, together with the pressure acting on the annular surface mentioned above, is greater than the force acting on the spool valve body 42 from the fuel in the control chamber 32 and the optionally present spring element 98. As soon as the slide valve body 42 is lifted from the control body 50, a supplementary flow of fuel from the high-pressure chamber into the control chamber 32 takes place via the gap 68 and the throttle inlet 66 formed in this way and the throttle duct 48, which leads to a rapid pressure increase in the control chamber 32 and a movement of the injection valve part 22 toward the injection valve seat 18 associated therewith.

Claims

1. A fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine, said fuel injection valve comprising: a housing (14) having a high-pressure inlet (16) for fuel at high pressure and an injection valve seat (18); a high pressure chamber (20) disposed in the housing (14) extending from a high pressure inlet (16) to an injection valve seat (18); an injection valve part (22) for interacting with the injection valve seat (18), which is arranged in the housing (14) so as to be longitudinally movable and spring-loaded against the direction of the injection valve seat (18); a double-acting control piston (26) formed on the injection valve part (22), said control piston defining a high-pressure chamber (20) on one side and a control chamber (32) on the other side; a spool body (42) guided in a sliding fit (40) defining a longitudinal axis (38), said spool 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) provided between the end sides (44, 46); a control body (50) which, with its front side (52) facing the slide valve body (42), forms a slide valve seat (54) which interacts with the second end face (46) of the slide valve body (42) and has a control channel (58) which, starting from the front side (52), is in flow connection with a throttle channel (48) and can be connected to a low-pressure chamber (62) by means of a pilot valve (60) and can be disconnected from the low-pressure chamber, wherein the throttle channel (48) and the control channel (58) are in flow connection with 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 the slide valve body (42) has a throttle inlet (66) which, starting from the second end face (46), opens into the control chamber (32) and which is closed when the slide valve body (42) rests against 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), the valve is characterized in that a pocket-shaped recess (70) which extends from the first end face (44) and at least approximately in the direction of the longitudinal axis (38) is formed on the spool body (42), the throttle channel (48) extends from the recess (70) and toward the second end face (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 channel (48) has a preferably pocket-shaped deepening (76) which is formed on the slide valve body (42) and which is open toward the second end face (46), into which deepening the throttle section (74) of the throttle channel (48) opens.

3. The fuel injection valve as claimed in claim 1 or 2, characterized in that the throttle inlet (66) extends at least approximately parallel to the longitudinal axis (38) and at least approximately adjoins the longitudinal axis (38).

4. The fuel injection valve as claimed in one of claims 1 to 3, characterized in that the second end face (46) has an annular nozzle sealing projection (86) which preferably directly surrounds the nozzle opening (84) of the side of the throttle inlet (66) and a ring sealing projection (90) which extends along a radially outer lateral surface (88) of the slide valve body (42), wherein the nozzle sealing projection (86) and the ring sealing projection (90) are intended for interacting with the slide valve seat (54), and the nozzle sealing projection (86) and the ring sealing projection (90) delimit a ring-shaped end-face deepening (92) radially on the inside, into which the throttle channel (48) opens and which opens out preferably over the entire surface of the control body (50).

5. The fuel injection valve as claimed in claims 2 and 4, characterized in that the deepening (76) is preferably open over the entire surface toward the end-side deepening (92).

6. Fuel injection valve according to one of claims 1 to 5, characterized in that a spring element (98) is provided in the recess (70), which spring element is supported on the one hand on the slide valve body (42) in the recess (70) and on the other hand on the injection valve part (22).

7. The fuel injection valve as claimed in one of claims 1 to 6, characterized in that a 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, preferably at least approximately three quarters, of a spacing (A) between the first and second end sides (44, 46).

8. The fuel injection valve as claimed in one of claims 1 to 7, characterized in that the smallest cross-sectional area of the recess (70) is at least five times the sum of the smallest cross-sectional areas of the throttle inlet (66) and the throttle channel (56).

9. The fuel injection valve as claimed in one of claims 1 to 8, characterized in that the throttle channel (48) and the control channel (58) are preferably continuously in flow connection with the high-pressure chamber (20) via a throttle inlet (64) formed on the spool body (42).

10. The fuel injection valve as claimed in claims 2 and 9, characterized in that the throttle inlet (64) opens into the deepening (76).

11. The fuel injection valve according to one of claims 1 to 10, characterized in that the slide valve body (42) has a circumferential outer taper (148) in an end section facing the second end face (46) radially on the outside, which is loaded with fuel at high pressure.