KR20140147100A - Injector of a modular common-rail fuel injection system with throughflow limiter - Google Patents

Abstract

In an injector 1 of a modular common rail fuel injection system with a high pressure accumulator 6 integrated in the injector body, the injector 1 is axially movably guided and includes a nozzle needle A high pressure line 8 connecting the high pressure accumulator 6 with the nozzle chamber 19 and a component forming the high pressure accumulator 6 and in particular the accumulator pipe 25, And a holding body 5 screwed on the front surface of the high pressure accumulator 6. The high pressure line 8 extends through the holding body 5 and is located behind the high pressure accumulator 6 in the fluidized bed, ) For limiting the amount of fuel to be delivered to the injection nozzle (2). The perfusion limiter 26 is formed as a separate part which is disposed between the holding body 5 and the accumulator pipe 25 and is fixed by screwing between the holding body 5 and the accumulator pipe 25.

Description

TECHNICAL FIELD [0001] The present invention relates to an injector of a modular common rail fuel injection system having a flow restrictor,

The present invention relates to a sprayer of a modular common rail fuel injection system with a high pressure accumulator integrated in an injector body, the sprayer comprising an injection nozzle movably guided in an axial direction and having a nozzle needle surrounded by a nozzle chamber, A high pressure line connecting the accumulator to the nozzle chamber and a component forming a high pressure accumulator, in particular a holding body threadedly engaged with the accumulator pipe, the high pressure line extending through the holding body, At the rear of the high pressure accumulator, a perfusion limiter for limiting the amount of fuel delivered from the high pressure accumulator to the injection nozzle is disposed.

Such an injector is disclosed in DE 10210282 Al.

Modular common rail systems are characterized in that a portion of the accumulator volume present in the system is present in the injector itself. Modular common rail systems are used in large engines where individual injectors are mounted at large distances from one another in some cases. The sole use of rails common to all the injectors is undesirable in the engine because the injection pressure drops significantly during the injection due to the long lines and therefore the injection rate is also significantly reduced for longer injection durations. Accordingly, in such an engine, a high-pressure accumulator is disposed inside each injector. This configuration is referred to as a modular configuration since each individual injector can be used as a proprietary module including a unique high pressure accumulator. In this case, the high pressure accumulator is a pressure vessel with a supply line or discharge line, rather than a normal line. Since the diameter of the pressure-resistant vessel is much larger than that of the high-pressure line, a specific injection amount can be released from the high-pressure accumulator without causing an immediate pressure drop.

In the case of a common-rail system, leakage may occur within the line system or by a faulty injection valve in an undesirable situation. Injection valves with nozzle needles that cause continuous injection into the combustion chamber cause a lot of damage. Such damage can cause a fire in the vehicle or the destruction of the engine. In order to avoid such a risk, a perfusion limiter having a closing function is known, and the perfusion limiter separates the injection pump side high pressure from the injection valve by closing the supply part for the associated injector when the maximum withdrawal amount from the high pressure accumulator is exceeded do.

In the case of an injector incorporating a high pressure accumulator, the flow restrictors are usually located in front of the accumulator volume when viewed in the flow direction. In a so-called top-feed injector (in which the supply of fuel is made through the high-pressure connection of the injector on the upper side of the high-pressure accumulator), the perfusion restrictor is usually mounted on the upper end of the injector. In a so-called side-feed injector (the fuel supply is made through a lance in side contact with the injector), the perfusion limiter is usually placed in front of the pipe connection in the T-part. Further, there is also provided a configuration in which the restriction member is disposed behind the accumulator volume in terms of the flow surface. Here, the perfusion limiter housing is pushed into the injector holding body or is mounted in the holding body by a retaining ring.

The perfusion limiter disposed in front of the accumulator volume in the flow plane is set much more incorrectly. The reason is due to the damping effect of dead time and accumulator volume and the influence of different fuel parameters such as temperature and viscosity or fuel type (diesel or heavy oil). Another disadvantage of the perfusion restrictor placed in front of the accumulator volume in terms of the flow surface is that a much greater amount can be injected due to the expansion volume of the high pressure accumulator during closure of the perfusion restrictor. These characteristics are particularly categorized as critical in the highly conservative business of large marine engines. Also, the installation of the perfusion limiter at the upper end of the top-feed injector lowers the oscillatory load capacity of the injector by increasing the mass. In the case of a side-feed injector, complex T-components are required. Two different solutions are needed for the two injector concepts, which increases component variability.

Perfusion restrictors mounted in the rear of the accumulator volume in terms of the flow surface either require pressure fitting in the holding body in a press fit configuration or require complex bore crossings when mounted by the retaining ring. The two configurations are highly undesirable in terms of durability at extreme compressive loads given in the common rail system. In a system with a system pressure of 2200 bar, a compressive load of up to 2500 bar is observed.

The object of the present invention is to increase durability and not require recesses or additional critical bore intersections especially for pressure fitting and retaining rings in the holding body. In addition, one and the same configuration concept must be used for the top-feed injector and the side feed injector. A configuration with a functionally optimal perfusion limiter should be formed without adversely affecting the high-pressure load capacity of the holding body or high-pressure accumulator as a whole, at the same component cost as the prior art.

In order to solve the above problems, the present invention proposes that in the above-described injector, the restriction member is formed as a separate component which is disposed between the holding body and the accumulator pipe and fixed by screwing the holding body and the accumulator pipe do. By placing the perfusion restrictor between the holding body and the accumulator pipe, the advantage of the perfusion restrictor mounted behind the accumulator volume in terms of the flow surface is utilized. There is no need to press or fix by the retaining ring and there is provided a simple structure with high durability, because the restriction member is disposed between the holding body and the accumulator pipe and fixed by screwing the holding body and the accumulator pipe. The perfusion restrictor part is supported only by the axial force generated when the holding body and the accumulator pipe are threaded, and is fixed without further fixing means between the two parts.

Thus, in order to prevent rotational moment acting on the perfusion flow restrictor component from causing twisting of the perfusion flow restrictor component when the holding body and accumulator pipe are threaded, in a preferred refinement of the present invention, And is prevented from being twisted by the direction fixing pin.

On the one hand, in order to form a reliable support of the perfusion flow restrictor part and, on the other hand, a high-pressure seal type connection, preferably the flow restrictor part comprises a shoulder with a conical first sealing surface, Interacts with the conical sealing surface formed in the heel of the accumulator pipe.

The further high-pressure sealing engagement preferably includes a second sealing surface on the front side facing the holding body and the second sealing surface interacts with a conical sealing surface formed on the front surface of the holding body, . In this case, the arrangement of the anti-twist means in the form of safety pins can be omitted.

When a conical sealing surface is provided between the perfusion restrictor component and the holding body, the direct connection of the perfusion restrictor and the high pressure bore of the holding body in the top-feed injector is not made, but the conical second sealing surface of the perfusion restrictor component is held A design can be given that limits the hollow chamber formed between the body and the perfusion restrictor component. The connection is made through the hollow chamber, in which an additional high-pressure line, connected in parallel to the high-pressure line, extends through the holding body and the further high-pressure line is connected to the nozzle chamber on the one hand and to the high-pressure accumulator It is particularly preferable when it is connected. In this case, the high pressure line and the additional high pressure line lead into the hollow chamber, so that the two lines are fed with fuel flowing through the flow restrictor.

In this case, it is particularly preferable that the additional high-pressure line is formed as a resonator line connected to the high-pressure accumulator through the resonator choke.

The flow connection of the perfusion limiter and the two high pressure lines may alternatively be achieved by connecting the high pressure line and the additional high pressure line to the perfusion limiter through the bore intersection formed in the perfusion restrictor component. This embodiment is particularly preferred for a side-feed injector in which the fuel quantity at the time of closing the perfusion restrictor should not flow directly from the side fuel supply to the injection nozzle (bypass of the perfusion restrictor).

In the case of a side-feed injector, the connection of the fuel supply and the high-pressure accumulator is such that the injector comprises a fuel supply side connection, the connection is connected to the supply bore, the first section of the supply bore is formed in the holding body, The section is configured to axially penetrate the perfusion restrictor portion. The bypass of the perfusion restrictor is preferably prevented because the perfusion restrictor component includes a second flat sealing surface toward the holding body and the sealing surface interacts with the flat front of the holding body.

The formation of a perfusion limiter as a separate component enhances the flexibility of its structural design. In this regard, it is preferred that the perfusion flow restrictor component comprises a housing with a housing inlet on the side of the high pressure accumulator and a housing outlet on the housing body side, and a housing, which is longitudinally movable between a starting position and an end position in the chamber of the housing, The closure member hydraulically connecting the housing inlet and the housing outlet to each other via at least one channel including chocks and a flow connection between the housing inlet and the housing outlet, . In particular, the retaining ring fixed within the perfusion restrictor part can define the starting position of the closure member.

The present invention also relates to a perfusion restrictor component for use in an injector according to the invention, wherein said perfusion restrictor component comprises a perfusion restrictor, said perfusion restrictor comprising a high pressure accumulator side inlet, a holding body side outlet, And a closing member which is longitudinally movable between a starting position and an ending position in the chamber and which is subjected to a spring pre-stress in opposition to the flow direction, said closing member comprising at least one channel comprising choke, Hydraulically, and controls the flow connection between the inlet and outlet. The perfusion flow restrictor component includes a first, inlet-side axial section and a second, outlet-side axial section, the second section having a larger diameter than the first section, Wherein the section comprises a conical first sealing surface on the shoulder and a second sealing surface on the front facing each other, the second sealing surfaces being each capable of being pressed against the corresponding surface. The arrangement of the sealing surface in the second section with a larger diameter ensures that the part is disposed between the holding body and the accumulator pipe and can be fixed by screwing of the holding body and the accumulator pipe. The first section, in this case, protrudes into the chamber of the high pressure accumulator and is actuated by fuel pressure.

In a preferred refinement, the inner diameter of the first sealing surface lies radially spaced from the periphery of the first section. This results in a ring gap between the first axial section and the inner surface of the high-pressure accumulator upon assembly of the restrictor component, so that the fuel pressure acts not only inside, but also externally, As a result, a pressure compensation region is formed.

According to the present invention, an injector with enhanced durability is provided.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in detail below with reference to the embodiments shown in the drawings.
1 is a cross-sectional view showing a schematic configuration of an injector of a modular common rail fuel injection system according to the prior art;
Figure 2 is an enlarged view of the injector in section II of Figure 1 in a first embodiment;
3 is an enlarged view of the injector of the second embodiment.
4 is an enlarged view of the injector of the third embodiment;
5 is an enlarged view of the injector of the fourth embodiment.

1 shows an injector 1 comprising an injection nozzle 2, a choke plate 3, a valve plate 4, a holding body 5 and a high-pressure accumulator 6. In this case, the nozzle fixing nut 7 screwed to the holding body 5 binds the injection nozzle 2, the choke plate 3, and the valve plate 4. The solenoid valve 13 is closed in the idle state so that the high pressure fuel is discharged from the high pressure accumulator 6 through the high pressure line 8, the lateral connection 9 and the supply choke 10 to the control chamber of the injection nozzle 2 11, and the discharge from the control chamber 11 is blocked by the discharge choke 12 in the valve seat of the solenoid valve 13. The system pressure applied to the control chamber 11 pushes the nozzle needle 15 into the nozzle needle seat 16 together with the force of the nozzle spring 14 so that the injection holes 17 are closed. When the electromagnet of the solenoid valve 13 is actuated, the flow through the solenoid valve seat is released and the fuel returns from the control chamber 11 through the discharge choke 12, the solenoid valve armature chamber and the low pressure bore 18, Fuel tank. The equilibrium pressure defined by the flow cross section of the feed choke 10 and the discharge choke 12 is set in the control chamber 11. [ The equilibrium pressure is so small that the system pressure exerted in the nozzle chamber 19 can open the nozzle needle 15 which is guided movably in the nozzle body in the longitudinal direction so that the injection holes 17 are opened and the injection .

When the solenoid valve 13 is closed, the discharge path of the fuel through the discharge choke 12 is shut off. Fuel pressure is again generated in the control chamber 1 through the supply choke 10, which generates an additional closing force. This additional closing force reduces the hydraulic pressure to the pressure shoulder of the nozzle needle 15 and exceeds the force of the nozzle spring 14. [ The nozzle needle 15 closes the path with respect to the injection holes 17, thereby ending the injection process.

The resonator line 20 having the high-pressure accumulator side resonator choke 21 can be disposed parallel to the high-pressure bore 8, and the generated pressure peak can be quickly lowered by the resonator choke.

The supply of high-pressure fuel into the injector 1 by means of a high-pressure pump not shown in detail can be effected via a high-pressure connection 22 arranged on the top surface of the injector 1 (top-feed injector). Alternatively, the fuel supply can be effected through the injector 1, in particular via the high pressure connection 23 arranged laterally to the holding body 5 and the supply bore 24 extending to the high pressure accumulator 6 - feed injector).

2 to 5 show an enlarged view of a portion X of Fig. 1 with a perfusion restrictor disposed between the accumulator pipe 25, the high-pressure accumulator 6 and the holding body 5. Fig. 2 to 5 is that the perfusion limiter is formed in a separate perfusion restrictor part 26. [ The perfusion restrictor component 26 includes a first axial section 27 and a second axial section 28 and the second axial section 28 includes a larger axial diameter than the first axial section 27, Respectively. In the second axial section 28 the perfusion restrictor component 26 comprises a shoulder with a conical first sealing surface 29 which is in contact with the heel of the accumulator pipe 25 30 corresponding to the conical sealing surfaces. The heel 30 of the accumulator 25 is connected to the thin wall section 32 of the accumulator pipe 25 with a female screw 33 through a ring groove shaped recess 31. The perfusion limiter component 26 is inserted between the holding body 5 and the accumulator pipe 25 and is fixed by screwing these two parts together. In this case, the perfusion restrictor component 26 is protected from twisting by the pin 34. The sealing to the holding body 5 is made through a flat sealing point formed in the flat sealing surface formed on the front face of the holding body 5 in the embodiment according to FIGS. 2, 3 and 5, And interacts with the flat front of the holding body 5.

The perfusion restrictor component 26 includes an inlet 36 and an outlet 37. A piston 39 is movably guided in the axial direction in the chamber 38 and the piston 39 is urged against the retaining ring 41 by a compression spring 40. The piston 39 includes a blind hole 42 which is connected to the inlet 37 on the one hand and to the outlet 37 on the other hand through the choke bore 43. [ During operation, the injection volume is withdrawn from the chamber 38. As a result, the piston 39 is moved in the direction toward the lower sealing sheet 44 against the force of the spring, but does not reach the sealing sheet 44. During the non-injection time, the compression spring 40 presses the piston 39 back to its starting position. In this case, the chamber 38 is refilled via the choke 43. When the injection amount exceeds the prescribed maximum value, the piston 39 reaches the sealing sheet 44 and is moved to such an extent that the injection is terminated. The choke 43 causes a pressure loss between the fuel present in the blind hole 42 and the chamber 38. Upon exceeding the prescribed choke flow, the piston 39 is moved in the direction of the bottom sealing sheet 44 against the force of the spring, thereby terminating the injection.

In the embodiment according to FIG. 2, a single high-pressure line 8 is provided and the high-pressure line 8 extends through the holding body 5. The fuel passing through the restrictor (26) passes directly into the high pressure line (8) through the bore section (48).

3, an additional high voltage line 20 is arranged in parallel with the high voltage line 8 in the holding body 5, the further high voltage line 20 is formed as a resonator line, And is connected to the fuel supply unit through the choke 21. [ The two high-pressure lines 8 and 20 are supplied with fuel through a bore intersection 45 formed in the perfusion restrictor component 26.

In the embodiment according to Fig. 4, in the case of a top-feed injector, the sealing of the perfusion restrictor component 26 with respect to the holding body 5 can be effected by the conical seal 46. In this case, the anti-twist pin 34 is omitted. The conical sealing surface defining the conical seal 46 limits the hollow chamber 47 through which the outlet 37 on the one hand and the high pressure lines 8 and 20 on the other hand.

5 is a side-feed injector in which the fuel is guided into the high-pressure accumulator 6 through the supply bore 24 of the holding body 5 and the flow restrictor component 26. In this case, the supply bore 24 leads into the high pressure accumulator 6 via the accumulator choke 49.

1 injector
5 Holding body
6 High Pressure Accumulator
19 nozzle chamber
20 High-pressure line
21 resonator choke
23 connection
24 supply bore
25 Accumulator pipe
26 perfusion limiter
29, 35, 46 sealing faces
36 inlet
37 outlet
38 chamber
39 closing member
43 chokes
45 Bohr junction
47 hollow chamber

Claims (19)

An injector of a modular common rail fuel injection system having a high pressure accumulator integrated in an injector body, the injector comprising an injection nozzle movably guided axially and having a nozzle needle surrounded by a nozzle chamber, a high pressure accumulator, A high pressure line connecting to the chamber, and a component forming a high pressure accumulator, in particular a holding body threadedly engaged with the accumulator pipe, wherein the high pressure line extends through the holding body, and the high pressure accumulator And a perfusion limiter for limiting the amount of fuel delivered from the high pressure accumulator to the injection nozzle is disposed in the rear of the injector,
The perfusion limiter 26 is a separate component disposed between the holding body 5 and the accumulator pipe 25 and fixed by the screwing of the holding body 5 and the accumulator pipe 25 . ≪ / RTI > 2. An injector according to claim 1, characterized in that the holding body (5) and the restrictor element (26) are twisted by an axial pin (34). 3. The accumulator pipe (25) of claim 1 or 2, wherein the restrictor component (26) comprises a shoulder with a first conical sealing surface (29) And interacts with a conical sealing surface formed on the heel (30). 4. The device according to claim 1, 2 or 3, characterized in that the perfusion restrictor part (26) comprises a conical second sealing surface on the front face towards the holding body (5), the second sealing surface And interacts with a conical sealing surface formed on the front surface of the holding body (5). 5. A device according to claim 4, characterized in that said conical second sealing surface of said perfusion flow restrictor part (26) limits the hollow chamber (47) formed between said holding body (5) and said perfusion restrictor part Features a sprayer. 6. Device according to any one of claims 1 to 5, characterized in that an additional high-pressure line (20) connected in parallel with the high-pressure line (8) extends through the holding body (5) (20) is connected on the one hand to said nozzle chamber (19) and on the other hand to said high pressure accumulator (6). 7. An injector according to claim 6, characterized in that the further high-pressure line (20) is formed as a resonator line connected to the high-pressure accumulator (6) via a resonator choke (21). 8. An injector according to claim 6 or 7, characterized in that said high pressure line (8) and said further high pressure line (20) lead into said hollow chamber (47). 8. A device according to claim 6 or 7, characterized in that the high pressure line (8) and the further high pressure line (20) are connected to the perfusion restrictor via a bore intersection (45) formed in the perfusion restrictor part Features a sprayer. 10. A fuel injector according to any one of claims 1 to 9, wherein the injector (1) comprises a fuel supply side connection (23), the connection being connected to a supply bore (24) Section is formed in said holding body (5), said second section of said supply bore axially penetrating said perfusion restrictor part (26). 11. A device according to any one of the preceding claims, wherein the perfusion restrictor component (26) comprises a second sealing surface (35) flat on the front towards the holding body (5), the second sealing surface (35) interacts with the flat front of the holding body (5). 12. A device according to any one of the claims 1 to 11, characterized in that the restrictor element (26) comprises a housing with a housing inlet (36) on the high-pressure accumulator side and a housing outlet (37) on the housing body side, And a closing member (39) movable in the longitudinal direction between the starting and ending positions in the chamber (38) of the chamber (38) and subjected to spring pretensioning opposite to the flow direction, the closure member comprising at least one The housing inlet portion 36 is hydraulically connected to the housing outlet portion 37 through a channel of the housing inlet portion 36 and the housing outlet portion 37 to control the flow connection between the housing inlet portion 36 and the housing outlet portion 37 . 13. An injector according to claim 12, characterized in that the retaining ring (41) fixed in the restriction member (26) defines a starting position of the closing member (39). A perfusion restrictor component (26) for use in an injector (1) according to any one of claims 1 to 13, wherein the perfusion restrictor component comprises a perfusion restrictor, the perfusion restrictor comprising a high pressure accumulator inlet (36), a holding body side discharge (37), and a closing member (39) movable longitudinally between the starting position and the ending position in the chamber (38) and subjected to spring pre- The closure member hydraulically connects the inlet 36 and the outlet 37 to each other via at least one channel including the choke 43 and the inlet 36 and the outlet 37, For controlling the flow connection between the flow restrictor component
The flow restrictor component (26) includes a first, inlet-side axial section (27) and a second, outlet-side axial section (28) 1 section 27 and the second section 28 includes a second sealing surface 35, 46 on the front facing conical first sealing surface 29 and a second sealing surface 29 on the shoulder, And the sealing surfaces are each capable of being pressed against the corresponding surface. 15. A perfusion limiter component according to claim 14, wherein said second sealing surface (46) is conically shaped. 16. A perfusion flow restrictor according to claim 14 or 15, characterized in that the inner diameter of the first sealing surface (29) lies radially spaced from the outer diameter of the first section (27). 17. A perfusion limiter according to any one of claims 14 to 16, characterized in that the retaining ring (41) fixed in the perfusion restrictor part (6) defines a starting position of the closure member (39) Part. 18. A perfusion restrictor component according to any one of claims 14 to 17, wherein said outlet (37) leads into a bore intersection (45) formed in said perfusion restrictor part (26). 19. A perfusion flow restrictor part according to any one of claims 14 to 18, characterized in that the second section is penetrated by the supply bore (24).

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