WO2016188577A1 - Common rail injector - Google Patents

Abstract

The invention relates to a common rail injector (10) comprising an injector housing (11) in which a nozzle needle (25) - arranged such that it can move in strokes - is arranged in a high-pressure chamber (18) for releasing or blocking at least one injection opening (15) formed in the injector housing (11), wherein an end region of the nozzle needle (25) facing away from the at least one injection opening (15) dips into an element (36) to form a control space (38), and wherein the nozzle needle (25) cooperates with a device (50) for limiting the maximum opening stroke of the nozzle needle (25), which device preferably has a first preferably sleeve-like element (33), which is arranged axially fixed on the nozzle needle (25) and is applied with force by a reset spring (34) in the closing direction of the nozzle needle (25), and which device has a second, preferably likewise sleeve-like element (35; 35a) which radially surrounds the nozzle needle (25) and is arranged axially fixed in the injector housing (11) on the side facing away from the first element (33).

Description

 Description title

 Common rail injector prior art

The invention relates to a common rail injector according to the preamble of claim 1.

Such a common rail injector is known from DE 199 36 668 A1 (FIG. 7) of the Applicant. In the known common rail injector is the

High-pressure chamber substantially within a nozzle body of the

Injector designed. In addition, a control chamber sleeve is arranged in the area of the nozzle body, in which area the end region of a nozzle needle which is opposite an injection opening is immersed. The nozzle needle is by means of a closing or return spring in its closing direction

with force. For this purpose, the closing spring is supported, on the one hand, against a support ring which bears against a radially encircling collar of the control chamber sleeve and, on the other hand, against a sleeve-shaped element which radially surrounds the nozzle needle. The sleeve-shaped element is located at the axial intermediate position of a support ring at a diameter stage of the nozzle needle. To limit the maximum stroke of the nozzle needle during its opening movement, an axial gap is formed between the mutually facing end faces of the control chamber sleeve and of the element, the size of which depends on the maximum stroke. When reaching the maximum stroke, the nozzle needle radially surrounding element with its end face on the end face of the

Control chamber sleeve on.

In addition, known from the prior art common rail injectors with nozzle needles, which in contrast to the disclosed in DE 199 36 668 A1 nozzle needle axially over several portions of the

Injector housing extend. An Axialhubanschlag by separate or specially designed components as in the aforementioned prior art is not provided in such common rail injectors. Rather, the maximum stroke in such a common-rail injector limited by the fact that the injection opening facing away from the end face of the nozzle needle axially abuts a the control chamber on the side facing away from the nozzle needle side surface of the control chamber.

Disclosure of the invention

Based on the illustrated prior art, the present invention seeks to provide a common rail injector according to the preamble of

Claim 1 such that the setting of the maximum achievable opening stroke of the nozzle needle is made possible even in relatively long nozzle needles, at the same time an advantageous assembly of the nozzle needle and the directly cooperating with the nozzle components of the

Hubbegrenzungseinrichtung should be possible. Furthermore, a local

Separation of a control chamber and the setting of the maximum achievable opening stroke of the nozzle needle can be achieved in order to form the respective components optimally. This object is achieved with a common rail injector with the

Characteristics of claim 1 achieved in that the nozzle needle, a second element of the means for adjusting the maximum stroke of the nozzle needle, which comprises the nozzle needle radially and on the first element

axially facing away from the injector housing, axially completely penetrated and the dipping into the control chamber end of the

Nozzle needle is arranged axially spaced from the second element. In other words, this means that the device for limiting the maximum opening stroke of the nozzle needle from the control chamber or the control chamber forming the second element is arranged separately or

is trained. This makes it relatively long, especially when used

Nozzle needles possible, the control room on the at least one

Injection opening in the injector housing facing away from the nozzle needle, and to arrange the means for limiting the maximum opening stroke of the nozzle needle relatively close to the at least one injection opening in the injector. Such a functional separation of the modules allows in particular, an advantageous assembly of the components of the common rail injector.

Advantageous developments of the common rail injector according to the invention are listed in the subclaims.

In an advantageous constructive implementation of the general concept of the invention, it is provided that the device for adjusting the maximum stroke of the nozzle needle is arranged in the region of a nozzle body to which at least one further housing element adjoins on the side facing away from the at least one injection opening in the axial direction, and the control chamber is arranged in the region of the further housing element.

To form an axial stop for the second element of the device for limiting the maximum opening stroke of the nozzle needle, it is preferably provided that the further housing element with an end face facing the nozzle body forms an axial stop surface for the second element of the device. Such a design has the advantage that a stop for the second element can be formed without additional components, since this is formed by the second element facing end face or end face of the other housing element.

In a constructive development or refinement of this inventive idea, it can be provided that the high-pressure space in the nozzle body and in the further housing element is formed on mutually facing sides of a respective bore portion, wherein the hole formed in the further housing element bore portion for forming the stop surface for the second element has a smaller diameter has as the bore formed in the nozzle body portion, and that the second element has at least one passage for fuel between the two bore portions. This passage is therefore of particular importance, since it ensures that an inflow of fuel into the region of the at least one injection opening is made possible even when the nozzle needle is maximally open, in which the second element bears against the end face of the further housing element. On the one hand to achieve the highest possible flow cross section in the direction of the at least one injection opening through the second element, and at the same time to construct the second element structurally particularly simple and rigid, it is provided that the at least one passage in the second element than over a partial area the axial extent of the second

Elements extending longitudinal slot is formed by the

Nozzle body facing away from the end face of the second element.

To limit the wear between the two elements of the

Device for limiting the maximum opening stroke and for setting the maximum opening stroke, it is provided that the mutually facing end faces of the two elements at maximum stroke of the nozzle needle in

Are contact, and that the maximum opening stroke of the nozzle needle is defined by the size of an axial gap formed between the end faces of the two elements.

As explained in the section prior art, serves a reset or

Closing spring for applying force to the nozzle needle in its closed position, on the one hand during operation of the common rail injector in an interruption of the control, the nozzle needle to move it to its closed position, and on the other hand to avoid undesirable injection of fuel into the combustion chamber of an internal combustion engine. For this purpose, a precise vote of the spring stiffness or the characteristic of the closing spring is required. In a further embodiment of the invention, it may be provided that the maximum opening stroke of the nozzle needle by the in the

 Control chamber dipping end portion of the nozzle needle is limited, and that at maximum opening stroke of the nozzle needle, the two elements are arranged spaced apart to form an axial gap formed between the two elements. The two elements thus serve to adjust or exact positioning of the closing spring in relation to

 Nozzle needle, and not the limitation of the maximum opening stroke of the nozzle needle.

In a further constructive design of the fuel! It can be provided that the nozzle needle has a radially encircling seat for the first element, against which the first element bears axially, that the second element under axial intermediate position of the return spring adjoins the first element that the movement of the second element is limited by a nozzle module, wherein the nozzle needle is part of the nozzle module, and that the nozzle module forms a pre-assembled into the injector housing, preassembled module.

Finally, a further structurally preferred embodiment provides that the high-pressure chamber is hydraulically connected to an inlet channel for fuel under high pressure, and that the inlet channel opens radially into the high-pressure chamber in an axial region lying between the at least one injection opening and the control chamber. In particular, it may be provided that the mouth region of the inlet channel in the

High pressure room in the middle between the at least one

Injection opening and the control chamber opens. Such an arrangement of the inlet channel to the high-pressure chamber allows an optimized supply of both the control chamber and the region from which fuel flows through the at least one injection port into the combustion chamber of the internal combustion engine.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing.

This shows in:

1 shows a longitudinal section through a common rail injector according to the invention,

2 shows a partial region of the common rail injector according to FIG. 1 in FIG

 Area of a device for limiting the maximum opening stroke of its nozzle needle,

3 shows a setting ring in perspective view,

4 is a perspective view of a stop sleeve, Fig. 5 is provided with the adjusting ring and the stop sleeve

 Nozzle needle in side view,

6 shows a comparison with FIG. 2 modified common rail injector,

 also in longitudinal section,

7 shows a comparison with FIGS. 1 to 4 modified common rail injector, in longitudinal section,

Fig. 8 is a used in the common rail injector according to FIG. 7

 Adjustment ring in perspective view and

Fig. 9 is a used in the common rail injector according to FIG. 7

 Stop ring, also in perspective view.

The same elements or elements with the same function are provided in the figures with the same reference numerals.

The common rail injector 10 shown in FIG. 1 is used for injecting fuel into the combustion chamber, not shown, of an internal combustion engine, in particular a self-igniting internal combustion engine. The injector 10 has an injector housing 11 consisting of several parts. In the illustrated embodiment, the injector housing 1 1 essentially comprises two parts, a nozzle body 12 and a connected to the nozzle body 12 in the axial direction housing member 13, which in practice usually consists of several, also interconnected and in the axial direction

subsequent parts. The pressure-tight connection between the nozzle body 12 and the housing 13 in a conventional manner by means of a nozzle lock nut 14. On the combustion chamber of the

Internal combustion engine side facing the nozzle body 12 at least one injection port 15 for injecting fuel. Within the injector housing 11, a high-pressure chamber 18 is formed, which is also formed by a plurality of well portions formed in the nozzle body 12 with different diameters and a plurality of bore portions formed in the housing member 13, also with different

Diameters, is formed. The high-pressure chamber 18 can be supplied via an inlet channel 19 with fuel under system pressure. The inlet channel 19 opens in the illustrated embodiment, approximately in a central region of the high pressure chamber 18 (based on the axial extent of the injector 10), wherein it radially, ie

perpendicular to a longitudinal axis 21 of the injector 10, in the high-pressure chamber 18 opens. On the inlet channel 19 opposite side of the

Injector 11, a drain passage 22 is formed, which serves for discharging located in a low-pressure region 42 of the injector 10 fuel.

Within the injector housing 1 1, a nozzle needle 25 in the direction of the double arrow 26 is arranged in a liftable manner in the longitudinal axis 21. In the lowered position of the nozzle needle 25 shown in FIG. 1, the at least one formed in the injector 1 1 and the nozzle body 12 is formed

Injection opening 15 at least indirectly closed to an injection of

To avoid fuel in the combustion chamber of the internal combustion engine. For this purpose, between the at least one injection opening 15 facing

End portion 27 of the nozzle needle 25 and the inside of the nozzle body 12 is formed a sealing seat. In the lifted position of the nozzle needle 25 of the sealing seat is in contrast a manner known per se

Outflow of fuel from the high pressure chamber 18 through the at least one injection port 15 into the combustion chamber of the internal combustion engine allows.

The nozzle needle 25 is part of a nozzle module 30 shown in FIG. 5. The nozzle module 30 comprises in the axial direction next to the

Nozzle needle 25 is still a pin-shaped center piece 31 and a likewise pin-shaped valve piston 32. The nozzle needle 25, the middle piece 31 and

Valve piston 32 are welded together in the transverse direction, in particular by laser welds. In the area of the nozzle needle 25, the nozzle module 30 moreover has a stop sleeve 33 forming a first element of a device 50 for limiting the maximum opening stroke of the nozzle needle 25, a return spring 34 designed as a compression spring and an adjusting ring 35. The adjusting ring 35 forms a second element of the device 50 for limiting the maximum opening stroke of the nozzle needle 25 and is completely penetrated or penetrated by the nozzle needle 25 in the axial direction.

The stop sleeve 33, the return spring 34 and the adjusting ring 35 are at the nozzle needle 25 mounted before the nozzle needle 25 is welded to the center piece 31. Due to the different diameters of the nozzle needle 25 and the central piece 31, the stop sleeve 33, the return spring 34 and the adjusting ring 35 after welding the nozzle needle 25 with the central piece 31 axially captive with said components or the

Nozzle module 30 is connected, wherein the nozzle module 30 represents a preassembled unit for the injector 10.

Within the injector housing 11 is on the at least one

Injection opening 15 facing away from the nozzle module 30 a

Control chamber sleeve 36 is arranged. The control chamber sleeve 36 has, on the side facing the valve piston 32, a blind bore 37, into which the valve piston 32 of the nozzle module 30 with its end region 44 dips.

In particular, the end portion 44 is axially spaced from the device 50 and the adjusting ring 35, respectively. The valve piston 32 limited within the

Blind hole 37 a control chamber 38 which has an inlet bore 39 to the high-pressure chamber 18 hydraulically connected. The control chamber 38 is hydraulically relieved via a formed in the control chamber sleeve 36 through hole 41 in the low pressure region 42 of the injector 10, which in turn is connected to the drain passage 22.

The through-hole 41 is on the side facing away from the valve piston 32 by means of a spherical valve member 43 in the exemplary embodiment

closable. The actuation of the valve member 43 is done by way of example, and not limitation, via a Magnetaktuator 45 in a conventional manner and

Way, such that when energizing the Magnetaktuators 45 the

Valve member 43 lifts off from the through hole 41, to allow an outflow of fuel from the control chamber 38 in the low pressure region 42 of the injector 10. The fuel flowing out of the control chamber 38 also causes, in a known manner, an actuation of the nozzle module 30 or the nozzle needle 25 such that the nozzle needle 25 lifts off its sealing seat to release the at least one injection opening 15.

In Fig. 2 it is shown that the stop sleeve 33, the return spring 34 and the adjusting ring 35 within a bore portion 46 of

Nozzle body 12 are arranged. At the nozzle body 12 closes in axial direction of the housing member 13, wherein a in the end face 47 of the housing member 13 opening bore portion 48 has a smaller diameter than the bore portion 46 in the region of the adjusting ring 35 and the bore portion 46. Thus, the end face 47 forms for the facing end face of the adjusting ring 35 an axial stop.

As can be seen in particular with reference to FIG. 3, the adjusting ring 35 has, by way of example, three longitudinal slots 49, which are arranged at equal angular intervals relative to one another and which each have a passage for fuel out of the

Forming bore portion 48 in the bore portion 46. The im

 Embodiment respectively in side view rectangular longitudinal slots 49 extend over a portion of the length L of the adjusting ring 35, and go from the housing member 13 facing the end face of the adjusting ring 35. The nozzle needle 25 radially surrounding stop sleeve 33 has on the

Adjusting ring 35 facing away from a radially encircling collar 51 which abuts axially on a seat or a shoulder 52 of the nozzle needle 25. The return spring 34 is supported between the collar 51 and the return spring 34 facing end face of the adjusting ring 35 from. The return spring 34 acts on the nozzle needle 25 or the nozzle module 33 with a spring force such that the nozzle needle 25 in the direction of at least one

Injection opening 15 and is pressed in the direction of the sealing seat. In particular, the return spring 34 ensures that when the solenoid actuator 45 is de-energized, the nozzle needle 25 always forms the sealing seat in order to prevent fuel from being spiked into the combustion chamber of the internal combustion engine.

Between the collar 51 facing away from end face 53 of the stop sleeve 33 and the end face 53 facing end face 54 of the adjusting ring 35, an axial gap 55 is formed. The size of the axial gap 55 is adjusted by a variation of the length I of the stop sleeve 33. In particular, the maximum stroke of the nozzle needle 25 or of the nozzle module 30 in the opening direction is limited by the size of the axial gap 55. The end face 54 of the adjusting ring 35 thus forms a stop for the stop sleeve 33 in the opening direction of

Nozzle needle 25 off. When the magnet actuator 45 is energized and the associated pressure relief of the control chamber 38, the nozzle needle 25 moves counter to the spring force of the return spring 34 in the opening direction until the stop sleeve 33 axially abuts the adjusting ring 35, ie the axial gap 55 is zero. In this position, the reason of the blind hole 37 of the

Control chamber 38 facing end face of the valve piston 32 is still spaced from the bottom of the blind hole 37.

Alternatively, it may be provided according to the representation of FIG. 6 that the length I of the stop sleeve 33 is selected so small that the maximum opening stroke of the nozzle needle 25 and the nozzle module 30 by a concern of the valve piston 32 at the bottom of the blind bore 37 of the

Control room 38 takes place. In this case, even at a maximum

Opening stroke of the nozzle needle 35, as shown in FIG. 6, the stop sleeve 33 is still axially spaced from the adjusting ring 35, i. that an axial gap 55 greater than zero is always formed. In this configuration, in particular the installation space of the return spring 34 is defined or limited by the dimensioning of the adjusting ring 35 and the stop sleeve 33 so as to provide the required return characteristic or restoring force of

Set or define return spring 34.

FIGS. 7 to 9 show a fragmentary illustration of an injector 10a modified with respect to FIGS. 1 to 3. The injector 10a has, in addition to the stop sleeve 33, a sleeve-shaped adjusting ring 35a with a constant

Diameter with several, formed on its wall in the radial direction

Through hole 57 for the fuel. The adjusting ring 35a cooperates with a stop ring 58, which has a centering section 59 projecting into the adjusting ring 35a. In addition, the adjusting ring 35a has flat, closed end faces. The adjustment of the maximum axial gap 55 can be done by varying the height of the adjusting ring 35 a, wherein the

Setting ring 35a can be subsequently connected to the nozzle module 30.

The injector 10, 10a described so far can be modified or modified in many ways, without deviating from the inventive idea.

Claims

 claims 1. Common rail injector (10, 10a), with an injector housing (11) in which in a high-pressure chamber (18) for releasing or blocking at least one injection opening (15) formed in the injector housing (11), a nozzle needle arranged in a liftable manner (US Pat. 25), wherein one of the at least one injection opening (15) facing away from end portion of the nozzle needle (25) in an element (36) for forming a control chamber (38) is immersed, and wherein the nozzle needle (25) with a device (50) for Limitation of the maximum opening stroke of the nozzle needle (25)  cooperates, wherein the means (50) on the nozzle needle (25) - preferably axially stationary - arranged first, preferably sleeve-shaped element (33) which is subjected to force by means of a return spring (34) in the closing direction of the nozzle needle (25), and a second, preferably likewise sleeve-shaped element (35; 35a), which radially surrounds the nozzle needle (25) and is arranged axially stationary in the injector housing (11) on the side facing away from the first element (33), characterized in that the nozzle needle (25) the second element (35; 35a) is completely penetrated axially and the end region (44) of the nozzle needle (25) immersed in the control chamber (38) is arranged axially spaced from the second element (35; 35a). 2. Common rail injector according to claim 1,  characterized,  in that the device (50) is arranged in the region of a nozzle body (12), at least one further in the axial direction on the side facing away from the at least one injection opening (15) Housing element (13) connects, and that the control chamber (38) in the region of the further housing element (13) is arranged. Common rail injector according to claim 2, characterized, in that the further housing element (13) forms an axial stop surface for the second element (35; 35a) of the device (50) with an end face (47) facing the nozzle body (12). Common rail injector according to claim 3, characterized, in that the high-pressure chamber (18) is formed in the nozzle body (12) and in the further housing element (13) on mutually facing sides of in each case one bore section (46, 48) Housing member (13) formed bore portion (48) for forming the abutment surface for the second element (35; 35a) has a smaller diameter than that in the nozzle body (12) formed Bore portion (46), and that the second element (35; 35a) has at least one passage for fuel between the two bore portions (46, 48). Common rail injector according to claim 4, characterized, in that the at least one passage is formed as a longitudinal slot (49) extending over a partial region of the axial extension (L) of the second element (35) and extending from the end face of the second element (35) facing away from the nozzle body (12). Common rail injector according to claim 4, characterized, the at least one passage is formed as a through-bore (57). Common rail injector according to one of claims 1 to 6, characterized, in that, in order to limit the opening stroke of the nozzle needle (25), the mutually facing end faces (53, 54) of the two elements (33, 35) are in abutting contact with the maximum stroke of the nozzle needle (25), and in that maximum opening stroke of the nozzle needle (25) by the size of one between the end faces (53, 54) of the two elements (33, 35)  formed axial gap (55) is defined. Common rail injector according to one of claims 1 to 6,  characterized,  in that, for limiting the opening stroke of the nozzle needle (25), the mutually facing end faces (53, 54) of the two elements (33, 35a) are in abutting contact with maximum stroke of the nozzle needle (25) with the interposition of a stop ring (58), and in that the maximum opening stroke the nozzle needle (25) is defined by the size of an axial gap (55) formed between the one element (33) and the stop ring (58). Common rail injector according to claim 1,  characterized,  in that the maximum opening stroke of the nozzle needle (25) is limited by the end region (44) of the nozzle needle (25) that dips into the control chamber (38), and that with maximum opening stroke of the nozzle needle (25) the two elements (33, 35) are formed one between the two  Elements (33, 35) formed axial gap (55) are arranged spaced from each other. 0. Common rail injector according to one of claims 1 to 8,  characterized,  in that the adjustment of the maximum opening stroke of the nozzle needle (25) takes place via a variation of the length (I) of the first element (33) or of the second element (35a). 1. Common rail injector according to one of claims 1 to 7 or 9,  characterized,  in that the nozzle needle (25) has a radially encircling seat (52) for the first element (33), against which the first element (33) bears axially, that the second element (35) under axial intermediate position of the return spring (34) the first element (33) adjoins that the movement of the second element (35) is limited by a nozzle module (30), wherein the Nozzle needle (25) is part of the nozzle module (30), and that the Nozzle module (30) forms an insertable into the injector (1 1), preassembled module. 12. common rail injector according to one of claims 1 to 1 1,  characterized,  in that the high-pressure chamber (18) is hydraulically connected to an inlet channel (19) for high-pressure fuel, and in that the inlet channel (19) extends radially in an axial region lying between the at least one injection opening (15) and the control chamber (38) the high-pressure chamber (18) opens.