WO2009153086A1 - Fuel injection valve - Google Patents

Abstract

The invention relates to a fuel injection valve (1) which is especially used as an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines. The fuel injection valve comprises a multi-part valve housing (2) that consists of a housing part (5) at the top end, a nozzle body (3) and a retaining body (4) connecting the housing part (5) at the top end to the nozzle body (3). A control valve (6) is arranged in the housing part (5) at the top end while a plunger (13) is arranged in the nozzle body (3). A control chamber bore (20) is configured in the retaining body (4) and interacts with a face (25) of the plunger (13) to define a control chamber (26). The retaining body (4 is relatively long, thereby resulting in a correspondingly large volume of the control chamber bore (20). A filler piece (30) is arranged in the control chamber (26) so that the volume of the control chamber (26) is considerably reduced, thereby allowing a relatively direct control of the plunger (13) via the control valve (6).

Description

description

title

Fuel injector

State of the art

The invention relates to a fuel injection valve with a switching valve arranged on the head side. Specifically, the invention relates to the field of injectors for fuel injection systems of air compressing, self-igniting internal combustion engines.

From DE 199 56 522 Al an injector for injecting a fluid under high pressure by means of a nozzle is known. The known injector body comprises a high-pressure inlet line and a non-pressurized outlet. Furthermore, the injector body contains a solenoid valve, which serves to control the nozzle. In the injector, an axially extending sleeve is movably received, whose one end face is actuated by means of a valve and the other end face defines a control chamber into which a branch of a high-pressure inlet opens.

The known from DE 199 56 522 Al injector has the disadvantage that the design is relatively expensive. Specifically, in a diameter range extending in the injector from an outlet throttle in the upper region to a conical seat stop in the region of the nozzle, the Sleeve in the injector a clearance of more than 0.01 mm, wherein the diameter of the bore in the axially extending sleeve is in the range of 1.5 mm. And in the diameter range extending from the conical seat stop to the sleeve end face, the sleeve is mounted approximately free of play, specifically with a clearance of less than 0.01 mm, which places very high demands on the concentricity and machining quality of the sleeve component.

Disclosure of the invention

The fuel injection valve according to the invention with the features of claim 1 has the advantage that the manufacturability, in particular with respect to a control chamber bore, is improved, wherein a head-side arrangement of the switching valve in the fuel injection valve is possible.

The measures listed in the dependent claims advantageous developments of the fuel injection valve specified in claim 1 are possible.

It is advantageous that the filler is designed at least partially rod-shaped and that the filler at least partially through the

Control chamber bore of the holding body extends. In this case, the filler in the control chamber bore sections have a three- or polygonal cross-section, so that one or more retaining edges are formed. With the retaining edge, the filler can form an interference fit with the control chamber bore in order to achieve a reliable attachment of the filler in the control chamber bore. As a result, the filler is fixed in the axial direction. On the other hand, it may also be advantageous that the filler in the control chamber bore is axially displaceable. This has the advantage that pressure changes, which are generated by the switching valve for driving the nozzle needle, also or even substantially affect a displacement of the filler in the control chamber bore. Thereby, a throttle effect that occurs when the pressure change propagates through the gap between the filler and the control space bore can be reduced.

In this case, a dimensioning is particularly advantageous in which the diameter of the control chamber bore has a similar or the same size as the diameter of that part of the nozzle needle, which dips into the control chamber, wherein also the filler is arranged axially displaceable in the control chamber bore and not at rest an upper stop. In this case arises when opening and closing the nozzle needle only a small or no flow in the narrow gap between the filler and the inner wall of the control chamber bore, but the filler moves analogously to the nozzle needle up and down, so that little or no Fuel from the nozzle side of the filler located portion of the control chamber in the control valve side part or vice versa must be spent. Thus throttling effects in the narrow gap between the inner wall of the control chamber bore and the filler are also eliminated, and the pressure in the control chamber can largely be regarded as uniform.

In this embodiment, the filler can be inserted only in the control chamber bore, so that it remains axially displaceable therein. It is advantageous that a spring element is provided, that the filler has a shoulder, that the filler abuts at its shoulder on a nozzle body side stage of the control chamber bore and that the spring element presses the filler against the nozzle body side stage. As a result, the filler can be acted upon by the bias of the spring element in order to achieve an axial fixation of the filler. In this case, the spring element can be supported on the end face of the nozzle needle, whereby in addition a loading of the nozzle needle is possible, which optionally exerts a restoring force on the nozzle needle.

It is also advantageous that a nozzle spring is provided, which is supported on the one hand at a stage of the control chamber bore and on the other hand on a shoulder of the filler, and that the nozzle spring presses the filler against the end face of the nozzle needle. As a result, a plant of the filler can be achieved on the nozzle needle. As a result, an advantageous power transmission from the axially movable filler to the nozzle needle is possible. In addition, the nozzle spring can exert a restoring force on the nozzle needle for closing the fuel injection valve.

It is advantageous that a control room tube is provided, which is at least partially disposed in the control chamber bore, that the control room tube divides the control chamber bore into a control chamber surrounding the high-pressure part and a provided within the control room tube control chamber part, which forms the control chamber, and that the filler in the Control chamber part of the control chamber bore is arranged. In this case, the nozzle needle may be guided in the control room tube. It is also advantageous that the control room tube of a nozzle spring is acted upon, which is supported on the one hand on the control room tube and on the other hand on the nozzle needle.

Brief description of the drawings

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

Fig. 1 is a fuel injection valve in a schematic sectional view according to a first embodiment of the invention.

FIG. 2 shows the detail of a fuel injection valve designated II in FIG. 1 in accordance with a second exemplary embodiment of the invention; FIG.

FIG. 3 shows the detail of a fuel injection valve designated by III in FIG. 1 in accordance with a third exemplary embodiment of the invention;

Fig. 4 is an excerpt section through the fuel injection valve shown in Fig. 3 along the section line designated IV and

Fig. 5 is a fuel injection valve in a schematic sectional view according to a fourth embodiment of the invention.

Embodiments of the invention Fig. 1 shows a fuel injection valve 1 in a schematic sectional view according to a first embodiment of the invention. The

Fuel injection valve 1 can serve in particular as an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines. A preferred use of the fuel injection valve 1 is for a fuel injection system with a common rail, the diesel fuel under high pressure leads to a plurality of fuel injection valves 1. However, the fuel injection valve 1 according to the invention is also suitable for other applications.

The fuel injection valve 1 has a multi-part valve housing 2, which in this embodiment comprises a nozzle body 3, a holding body 4 and a head-side housing part 5. In this case, the nozzle body 3, the holding body 4 and the head-side housing part 5 are connected to each other in a suitable manner. The holding body 4 is at least partially disposed in the mounted state within a bore of an internal combustion engine. The head-side housing part 5 is arranged outside the bore, so that it can be made relatively large. This results in favorable installation conditions for components of the fuel injection valve 1, which are provided in the head-side housing part 5. In the head-side housing part 5, in particular, a switching valve 6 is arranged, which may have a magnetic actuator, a piezoelectric actuator or another actuator.

The valve housing 2 of the fuel injection valve 1 has a fuel inlet 7, which is connected for example to a common rail. From the fuel inlet 7 branches a fuel channel 8 from which is guided by the holding body 4 and opens into a further fuel channel 9 in the nozzle body 3. In the nozzle body 3, a fuel space 10 is formed, which is filled via the fuel channels 8, 9 in operation with fuel under high pressure. The nozzle body 3 has a valve seat surface 11 which cooperates with a valve closing body 12 of a nozzle needle 13 arranged in the nozzle needle 13 to a sealing seat. When opening the nozzle needle 13 along an axis 14 of the sealing seat is released, so that fuel from the fuel chamber 10 via at least one nozzle opening 15 is hosed. The actuation of the nozzle needle 13 is described below in further detail.

The holding body 4 has a control space bore 20 which extends along the axis 14 substantially over the entire length of the holding body 4. In this case, an inlet throttle 21 is provided at the head end of the control chamber bore 20, via the fuel from the fuel inlet 7 into the control chamber bore 20 can be guided. In addition, an outlet throttle 22 is provided. The outlet throttle 22 can be connected via the arranged in the head-side housing part 5 switching valve 6 with a fuel return 23, which leads to a tank 24. The connection is controllable via the switching valve 6.

The nozzle needle 13 has an end face 25 which defines a control chamber 26 together with the control chamber bore 20. In this case, an inflow from the inlet throttle 21 and an outflow of fuel via the outlet throttle 22 is given in a head-side part 27 of the control chamber 26. In the control chamber 26, a filler 30 is arranged, which is almost extends over the entire length of the control chamber bore 20. Between the control chamber bore 20 and the filler 30, an annular gap-shaped part 28 of the control chamber 26 is formed. Furthermore, the control chamber 26 has a nozzle-side part 29. Through the filler 30, the fuel-filled volume of the control chamber bore 20 is significantly reduced. The filler 30 is formed of a solid, preferably a steel. Since the compression modulus of steel is significantly greater than the compression modulus of diesel fuel or the like, the filler 30 does not contribute to the elasticity of the control space 26 practically. As a result, even with a relatively large spatial distance between the arranged in the head-side housing part 5 switching valve 6 and arranged in the nozzle body 3 nozzle needle 13 a rigid connection of the nozzle needle 13 to the switching valve 6 without direct mechanical power transmission can be achieved.

By opening the outlet throttle 22, the pressure drops in the head-side part 27 of the control chamber 26, this pressure drop due to the reduced volume of the control chamber 26 leads relatively directly to a pressure drop in the nozzle-side part 29 of the control chamber 26. Due to the pressure drop in the area of the end face 25, the closing force of the nozzle needle 13 acting in the direction of the sealing seat is considerably reduced, so that the nozzle needle 13 lifts out of its seat and fuel is sprayed off via the nozzle opening 15.

After closing the outlet throttle 22 by means of the switching valve 6, the pressure builds up in the head-side part 27 and thus also in the nozzle-side part 29 of the control chamber 26 again. As a result, acts on the end face 25 of the Nozzle needle 13 a closing force, which is supported by the force of a nozzle-side part 29 of the control chamber 26 arranged nozzle spring 35. In this case, the nozzle spring 35 also ensures an axial fixation of the filler piece 30. For this purpose, the filler piece 30 has a shoulder 36 which rests against a nozzle-body-side step 37 of the control chamber bore 20. The nozzle spring 35 presses the shoulder 36 against the nozzle body-side stage 37. In order to ensure the flow from the annular gap-shaped part 28 of the control chamber 26 into the nozzle-side part 29 of the control chamber 26, at least one passage opening in the form of a recess or the like is provided on the step 37 ,

Fig. 2 shows the designated in Fig. 1 with II section of a fuel injection valve according to a second embodiment of the invention. In this embodiment, the filler 30 has a head portion 39, on which a shoulder 36 is provided. In this case, a nozzle spring 35 is located on the one hand on the nozzle body side step 37 of the control chamber bore 20 and on the other hand on the shoulder 36 of the head portion 39 of the filler 30 at. As a result, the filler 30 is pressed with its head part 39 against the end face 25 of the nozzle needle 13. The filler 30 is arranged axially displaceable, so that it follows the movement of the nozzle needle 13. The nozzle spring 35 acts on the nozzle needle 13 in the direction of the valve seat surface 11.

In the embodiment shown in FIG. 2, the filler 30 may be positioned at a lower stop, which is given in this embodiment by the end face 25 of the nozzle needle 13.

Fig. 3 shows the designated in Fig. 1 with III section a fuel injection valve 1 according to a third embodiment of the invention. In this embodiment, the filling piece 30 has at least one section 40, in which at least one edge 41 is formed on the filling piece 30. With the edge 41, the filler 30 is pressed against the control chamber bore 20, so that a fixation of the filler 30 in the axial direction, that is along the axis 14, is given.

FIG. 4 shows the section of the fuel injection valve 1 of the third, designated IV in FIG. 3

Embodiment. The filling piece 30 has a triangular cross-section in the section 40, so that the edges 41, 42, 43 are formed. In the region of the edges 41, 42, 43 while a press fit between the filler 30 and the control chamber bore is formed. The section 40 can be configured, for example, by grinding on the filler 30.

Fig. 5 shows a fuel injection valve 1 in a schematic sectional view according to a fourth embodiment of the invention. In this

Embodiment, a control room tube 50 is provided. The control room tube 50 is arranged in the holding body 4 of the valve housing 2. In this case, the control chamber tube 50 is inserted into the control chamber bore 20, wherein the control chamber 50, the control chamber bore 50 in a surrounding the control chamber 50 high-pressure part 51, which is designed ringpaltförmig, and a provided within the control chamber tube 50 control chamber part divides, which forms the control chamber 26. Further, within the control space tube 50, that is, in the control chamber 26, the filler 30 is arranged. The filler 30 is substantially rod-shaped and cylindrical designed. Between the filler 30 and the control chamber tube 50 an annular gap-shaped part 28 of the control chamber 26 is formed. Thus, the remaining for the fuel volume of the control chamber portion of the control chamber bore 20 is significantly reduced in the interior of the control chamber tube 50, so that even with a relatively long control chamber tube 50, a relatively small volume of the control chamber 26 results.

The inlet throttle 21, via which high-pressure fuel can flow into the head-side part 27 of the control chamber 26, is configured in the control chamber tube 50 in the region of the head-side part 27 in this exemplary embodiment. This can be done for example by a hole in the control room tube 50.

In this embodiment, the nozzle needle 13 has a pressure pin 52, with which the nozzle needle 13 is axially guided in the control chamber tube 50. In this case, the pressure pin 52 is designed in one piece with the nozzle needle 13. Furthermore, the nozzle spring 35 is placed on the pressure pin 52. In this case, the nozzle spring 35 is supported, on the one hand, on the control space pipe 50 and, on the other hand, on the nozzle needle 13. The pressure of the fuel in the control chamber 26 acts in the region of the nozzle-side part 29 of the control chamber 26 on the end face 25 of the nozzle needle 13, which is formed in this embodiment by the end face 25 of the pressure pin 52.

The invention is not limited to the described embodiments.

Claims

claims 1. Fuel injection valve (1), in particular injector for fuel injection systems of air-compressing, self-igniting internal combustion engines, with a switching valve (6) which is arranged in a head-side housing part (5), a nozzle body (3) via a holding body (4) with the Head housing part (5) is connected, and one in the nozzle body (3) arranged nozzle needle (13), characterized in that the holding body (4) has a control chamber bore (20) that the control chamber bore (20) and an end face (25) the nozzle needle (13) limit a control chamber (26) and that in the control chamber (26) a filler (30) is arranged. 2. Fuel injection valve according to claim 1, characterized in that the filler (30) is designed at least partially rod-shaped and that the filler (30) extends at least partially through the control chamber bore (20) of the holding body (4). 3. Fuel injection valve according to claim 1 or 2, characterized in that filler (30) in the control chamber bore (20) is axially displaceable. 4. Fuel injection valve according to claim 1 or 2, characterized in that a spring element (35) is provided, that the filler (30) has a shoulder (36), that the filler (30) rests on its shoulder (36) on a nozzle body side step (37) of the control chamber bore (20) and that the spring element (35) presses the filler (30) against the nozzle body side step (37). 5. Fuel injection valve according to claim 4, characterized in that the spring element (35) on the end face (25) of the nozzle needle (13) is supported. 6. Fuel injection valve according to claim 1 or 2, characterized in that a nozzle spring (35) is provided which is supported on the one hand at a stage (37) of the control chamber bore (20) and on the other hand on a shoulder (36) of the filler (30), and that the nozzle spring (35) presses the filler (30) against the end face (25) of the nozzle needle (13). 7. Fuel injection valve according to one of claims 1 to 3, characterized in that a control chamber tube (50) is provided, which is at least partially disposed in the control chamber bore (20), that the control chamber tube (50) the control chamber bore (20) into a control room tube (50) surrounding the high-pressure part (51) and within the control chamber tube (50) provided control chamber part which forms the control chamber (26), and that the filler (30) in the control chamber part of the control chamber bore (20) is arranged. 8. Fuel injection valve according to claim 7, characterized in that the control chamber tube (50) by a nozzle spring (35) is acted upon, on the one hand to the control chamber tube (50) and on the other hand to the nozzle needle (13) is supported. 9. Fuel injection valve according to claim 7, characterized in that the nozzle needle (12) is formed in its upper region with a guide diameter and that it is guided at this upper region in the control space pipe (50). 10. Fuel injection valve according to claim 1, characterized in that on the filler (30) at least in sections at least one retaining edge (41, 42, 43) is formed, wherein between the retaining edge (41, 42, 43) and the control chamber bore (20) Press fit is formed. 11. Fuel injection valve according to claim 10, characterized in that the filler (30) at least partially has a triangular cross-section.