EP3583310A1

EP3583310A1 - Fuel injector

Info

Publication number: EP3583310A1
Application number: EP18700107.8A
Authority: EP
Inventors: Armin HOFSTAEDTER; Franz Guggenbichler; Markus SCHWARZENBERGER; Sven Pasedach
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-02-20
Filing date: 2018-01-08
Publication date: 2019-12-25
Anticipated expiration: 2038-01-08
Also published as: CN110325728B; JP6802931B2; KR20190116443A; WO2018149555A1; EP3583310B1; DE102017202686A1; CN110325728A; JP2020507033A; KR102399897B1

Abstract

The invention relates to a fuel injector (1) for injecting fuel into the combustion chamber of an internal combustion engine, said fuel injector (1) comprising a nozzle body (5). A pressure chamber (8) is formed in the nozzle body (5), which is supplied with pressurized fuel via a feed bore (13). A longitudinally movable nozzle needle (7), which opens or closes at least one injection opening (9), is arranged in the pressure chamber (8). A cooling group (100) is arranged so as to at least partially surround the nozzle body (5). The cooling group (100) comprises a cooling ring (101) which delimits a plurality, preferably more than 20, flow channels (200) that can be flown through for cooling the nozzle body (5).

Description

description

fuel injector

State of the art

The invention relates to a fuel injector according to the preamble of

Claim 1.

A fuel injector for injecting fuel into the combustion chamber of an internal combustion engine is known from EP1781931 Bl. The known

Fuel injector includes an injector body and a nozzle body. The injector body and the nozzle body are clamped together by a nozzle lock nut. In the nozzle body, a pressure chamber is formed, which is supplied via an inlet bore with pressurized fuel. An at least one injection opening releasing or closing longitudinally movable nozzle needle is arranged to be longitudinally movable in the pressure chamber.

Furthermore, the known fuel injector in the nozzle body formed on cooling channels or flow channels. These cooling channels are used to cool the nozzle body and nozzle needle, especially in the combustion chamber facing areas.

The formation of the cooling channels in the nozzle body leads to a reduction in the strength of the nozzle body and thus its life. Furthermore, it is not possible to convert existing fuel injectors without active cooling simply on versions with cooling channels.

Furthermore, there are, especially when using several

Fuel injectors for a combustion chamber, operating points in which only a comparatively small amount of fuel is injected and consequently only a small internal cooling by the injected fuel quantity. This also applies, for example, to so-called dual-fuel engines, in which only a small amount of fuel, such as diesel, is injected to initiate an initial ignition of the main fuel gas.

Disclosure of the invention

In contrast, the cooling channels or flow channels of the fuel injector according to the invention for injecting fuel into the combustion chamber of an internal combustion engine do not reduce the strength of the nozzle body. In addition, active cooling can be easily retrofitted in conventional fuel injectors. Furthermore, the cooling of the nozzle body is carried out very effectively, since the effective cooling surface is comparatively large. It can also be used a quantity of cooling, regardless of the amount of fuel injected.

For this purpose, the fuel injector on a nozzle body. In the nozzle body, a pressure chamber is formed, which is supplied via an inlet bore with pressurized fuel. An at least one injection opening releasing or closing longitudinally movable nozzle needle is arranged in the pressure chamber. A cooling group is arranged at least partially surrounding the nozzle body. The cooling group comprises a cooling ring which has a multiplicity, preferably more than 20, of flow through

Flow channels for cooling the nozzle body limited.

Due to the large number of flow channels, the effective total cooling area of the cooling group is comparatively large, so that a very effective cooling group is created. The cooling group comprises the nozzle body in the radial direction at its end close to the combustion chamber. A weakening of the nozzle body by cooling channels in the nozzle body is thus no longer necessary.

Furthermore, it is possible to retrofit conventional fuel injectors without active cooling with a corresponding cooling group, so that an active cooling is retrofitted. The further design of the fuel injector does not have to be changed significantly. In advantageous developments, a longitudinal channel and a distributor groove are formed in the cooling group. The distributor groove runs close to the combustion chamber over almost the entire circumference of the cooling group. The longitudinal channel serves to supply the distributor groove with coolant. The coolant can be both Kraftoff, as well as an engine oil of the internal combustion engine, as well as a coolant of the

Internal combustion engine as well as a separate coolant of the fuel injector. When entering the cooling group, the coolant is directed through the longitudinal channel into the distributor groove and thus into the top of the cooling group. There is the most effective area of the cooling group, since it is the hottest area of the nozzle body.

In advantageous embodiments, the distributor groove is bounded in the circumferential direction by a longitudinal web arranged on the cooling group. The longitudinal web can be formed on the cooling ring. This is an adverse congestion or

Dead volume in the coolant flow avoided. This is preferably distributed

Coolant coming from the longitudinal channel in both directions of the distributor evenly, for example, in both circumferential directions over about 170 °.

In advantageous developments branch the flow channels of the

Distributor groove and run in a distance from the combustion chamber

Direction. Preferably, the individual flow channels are arranged parallel to each other. Advantageously, the flow channels are also arranged parallel to the longitudinal channel but have the opposite

Flow direction. As a result, the entire flow geometry is formed so that the pressure losses are minimized and all flow channels are flowed through in the same direction and almost the same amounts of coolant. At the same time, the large effective cooling surface of the cooling group already acts close to the combustion chamber in the hottest area of the nozzle body. In advantageous embodiments, a collector groove is formed in the cooling group, into which the flow channels open. As a result, the flow channels are reunited, so that it is possible for the coolant through only one

Outlet duct out of the cooling group. Preferably, the

Sammlernut thereby at the distributor groove opposite end of the

Cooling ring arranged. In advantageous embodiments, the nozzle body is braced by means of a nozzle retaining nut on the fuel injector. In the

Nozzle retaining nut supply channels for the supply and removal of the coolant are formed in and out of the cooling group. A first supply channel is hydraulically connected to the longitudinal channel, and a second supply channel is hydraulically connected to the collector groove. Thus is also the

Coolant supply separated from the nozzle body, so that it is not weakened in its strength. At the same time, the nozzle retaining nut combines several functions, namely for cooling and clamping. The

Nozzle clamping nut clamps the nozzle body with other components of the fuel injector, for example, with an injector body, optionally with the interposition of other components.

In advantageous embodiments, the flow channels extend parallel in an axial direction of the cooling group. As a result, all flow channels are flowed through in the same direction and almost the same amounts of coolant. Pressure losses in the flow channels are thus minimized.

In another advantageous embodiment, the flow channels meander, so in turns. Although the pressure loss through the flow channels thereby increases, but the higher flow rate increases the heat transfer into the flow channels.

In advantageous developments, the cooling group comprises a heat sink on which an inner transfer surface is formed. The transfer surface cooperates with an outer surface of the nozzle body. Ideally, the transfer surface contacts the nozzle body over a large area to ensure good heat conduction.

Advantageously, the longitudinal channel is formed between the cooling ring and the heat sink. As a result, the longitudinal channel can be easily manufactured, wherein the wall thicknesses of the cooling ring and heat sink can be minimized.

In advantageous embodiments, the cooling group comprises a cooling sleeve, which closes the cooling group to the environment media-tight. The cooling sleeve is included preferably arranged radially surrounding the cooling ring and ideally also has an end face to the combustion chamber.

Advantageously, the flow channels are formed between the cooling ring and the cooling sleeve. As a result, almost any geometry of the flow channels can be made. Furthermore, the wall thicknesses of the cooling ring and the cooling sleeve can be minimized.

In advantageous embodiments, the cooling group is made in one piece. The

Cooling group can be manufactured by means of rapid prototyping or 3D printing. This design minimizes the number of parts and has a very good seal of the flow channels.

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

These show in:

1 shows a longitudinal section through a fuel injector according to the prior art,

Fig. 2 shows schematically a section of an inventive

Fuel injector, with only the essential areas are shown,

3 shows a section through a cooling group according to the invention, wherein only the essential areas are shown,

Fig. 4 shows an embodiment of a cooling ring according to the invention in one

perspective view, with only the essential areas are shown.

The same elements or elements with the same function are provided in the figures with the same reference numerals. In Fig.l a fuel injector 1 for injecting fuel into the combustion chamber of an internal combustion engine is shown in longitudinal section, as is known from the prior art. The known fuel injector 1 comprises an injector body 2, a

Valve body 3, an intermediate plate 4 and a nozzle body 5. All these components are held together by a nozzle lock nut 6. The nozzle body 5 in this case contains a nozzle needle 7, which in an im

Nozzle body 5 formed pressure chamber 8 is arranged longitudinally displaceable. During an opening movement of the nozzle needle 7 fuel over several in

Nozzle body 5 formed injection openings 9 injected into the combustion chamber of the internal combustion engine.

At the nozzle needle 7, a collar is visible, on which a compression spring 10 is supported. The other end of the compression spring 10 is supported on a control sleeve 11, which in turn rests against the underside of the intermediate plate 4. The control sleeve 11 defines with the upper, the injection openings 9 opposite end face of the nozzle needle 7 and the underside of the intermediate plate 4 a control chamber 12. The pressure prevailing in the control chamber 12 pressure is decisive for the control of the longitudinal movement of the nozzle needle 7.

In the fuel injector 1, an inlet bore 13 is formed. About the

Zulaufbohrung 13, the fuel pressure on the one hand in the pressure chamber 8 is effective, where he exerts a force in the opening direction of the nozzle needle 7 via a pressure shoulder of the nozzle needle 7. On the other hand, this fuel pressure acts via a formed in the control sleeve 11 inlet throttle 15 in the control chamber 12 and holds, supported by the force of the compression spring 10, the nozzle needle 7 in their

Closed position. When an electromagnet 16 is subsequently driven, a magnet armature becomes

17 and a valve needle 18 connected to the magnet armature 17 are lifted off by a valve seat 19 formed on the valve body 3. The fuel from the control chamber 12 can flow in this way through an opening formed in the intermediate plate 4 outlet throttle 20 via the valve seat 19 into a drain passage 21. The lowering of the hydraulic force on the upper end face of the nozzle needle 7, which is brought about in this way, leads to an opening of the nozzle needle 7. The fuel from the pressure chamber 8 thus passes through the injection openings 9 into the combustion chamber.

As soon as the electromagnet 16 is switched off, the magnet armature 17 is pressed in the direction of the valve seat 19 by the force of a further compression spring 22, so that the valve needle 18 is pressed against the valve seat 19. In this way, the drainage path of the fuel via the outlet throttle 20 and the valve seat 19 is blocked. About the inlet throttle 15 is in the control room 12 again

Fuel pressure built up, whereby the hydraulic closing force is increased. As a result, the nozzle needle 7 is moved in the direction of the injection openings 9 and closes them. The injection process is then completed.

In order to cool the components in the region of the combustion chamber, cooling passages 30 are in valve body 3, intermediate plate 4 and nozzle body 5 of the known

Fuel injector 1 is formed. Thus, especially the tip of the nozzle needle 7 and the nozzle body 5 can be cooled. In the sectional view of Fig.l the cooling channels 30 are partially in the inlet bore 13. However, this is only due to the sectional view, in the embodiments, the cooling channels 30 are separated from the inlet bore 13.

However, the cooling channels 30 of the known fuel injector 1 reduce the strength of the nozzle body 5, so that according to the invention, the cooling channels 30 are formed outside of the nozzle body 5. Furthermore, these cooling channels 30 have a comparatively small total cooling surface.

2 shows in section a fuel injector 1 according to the invention in the region of the nozzle body 5, wherein only the essential areas are shown. A cooling group 100 is adjacent to the nozzle retaining nut 6 in the direction of

Brennraums arranged. The cooling group 100 surrounds the nozzle body 5 at least partially. The longitudinally movably arranged in the nozzle body 5

Nozzle needle 7 is not visible in the illustration of FIG. Furthermore, the injector 2, the valve body 3 and the intermediate plate 4 are shown only schematically as a black box. In the nozzle retaining nut 6, two supply channels 30 are formed, which

Supply or removal of the coolant in the cooling group 100 or from the Cooling group 100 are used: a first supply channel 30a is the supply and a second supply channel 30b is the discharge. The coolant may be both a special coolant and the fuel of the internal combustion engine and an engine oil for the internal combustion engine.

The cooling group 100 comprises a cooling body 102, a cooling ring 101 and a cooling sleeve 103. The cooling body 102 connects axially to the nozzle retaining nut 6 and is thus hydraulically connected to the two supply channels 30. At its inner diameter, the heat sink 102 is in contact with the nozzle body 5 in order to obtain a good heat conduction. The cooling ring 101 surrounds the combustion chamber near part of the heat sink 102 and has a plurality of cooling channels or flow channels. The cooling sleeve 103 seals the

Cooling group 100 and the cooling ring 101 from the environment, so that no

Coolant leakage can escape. As a result, the cooling sleeve 103 is the cooling ring

101 arranged radially surrounding.

The cooling group 100 is by means of various fixing elements 104, 105 to the

Nozzle clamping nut 6 and / or connected to the nozzle body 5. Various variants and connection techniques are possible.

3 shows a section through an embodiment of the cooling group 100 according to the invention. The cooling body 102 has a flange region 102a which axially adjoins the nozzle retaining nut 6. The heat sink 102 further has a central line region 102b and a cooling region 102c, which is the region of the heat sink closest to the combustion chamber

102 is. The flange portion 102a has the comparatively largest

Diameter and the cooling area 102c the comparatively smallest

Diameter of the heat sink 102. On the inside of the heat sink 102, a transfer surface 102d is formed, which cooperates with the nozzle body 5 and is designed for heat conduction, especially in the radial direction from the nozzle body 5 to the cooling ring 101. The transfer surface 102d can, as shown in FIG. 3, only extend over a circumference close to the combustion chamber

Cooling group 100 run, as well as over the entire length of the cooling group 100th The cooling ring 101 connects in the axial direction to the line region 102b and surrounds the cooling region 102c in the radial direction. An inlet channel 31 is formed in the cooling body 102 and opens into a longitudinal channel 111 delimited by the cooling ring 101, wherein the longitudinal channel 111 is preferably delimited by the cooling ring 101 and the cooling region 102c. The inlet channel 31 penetrates the flange area 102a and the line area 102b. The longitudinal channel 111 opens into a distributor groove 112 formed between the cooling ring 101 and the cooling sleeve 103. The distributor groove 112 represents the region of the cooling channels which is closest to the combustion chamber. The distributor groove 112 distributes the coolant over almost the entire circumference of the cooling group 100.

The detailed flow guidance of the coolant through the cooling ring 101 will be described in more detail later in FIG. After flowing through the cooling ring 101, the coolant passes into a collector groove 113 formed between the line region 102b and the cooling ring 101. From the collector groove 113, an outlet channel 32 which is pronounced in the heat sink 102 branches off, from which the coolant from the cooling group 100 returns back into the

Nozzle locknut 6 is guided.

On the cooling ring 101, a separating web 116 is formed in the longitudinal direction, which delimits the distributor groove 112 in the circumferential direction. The separating web 116 is preferably arranged diametrically opposite the longitudinal channel 111. By this arrangement, the distribution groove 112 branches from the

Longitudinal channel 111 from in both circumferential directions to about 170 ° each.

4 shows a preferred embodiment of the cooling ring 101 according to the invention in a perspective view, viewed from the region of the combustion chamber. The cooling ring 101 has an inner wall 110, which is pressed onto the cooling region 102c of the heat sink 102. In this case, the inner wall 110 is interrupted only by the longitudinal channel 111, so that it is delimited by the cooling region 102c and the cooling ring 101.

The cooling ring 101 has a plurality of longitudinal webs 115 in the axial direction and a plurality of cooling channels or flow channels 200 between them. The flow channels 200 extend in the axial direction from the distributor groove 112 at the combustion chamber end of the cooling ring 101 to the collector groove 113 at the line region 102b subsequent end of the cooling ring 101. A

Flow channel 200 is consequently limited in the radial direction by the inner wall 110 and the cooling sleeve 103, and in the circumferential direction by two longitudinal webs 115 and by a longitudinal web 115 and the separating web 116.

The flow path of the coolant through the cooling group 100 is as follows:

The coolant flows, for example coming from the supply channel 30 of the nozzle lock nut 6, in the input channel 31 and from there via the longitudinal channel 111 in the distribution groove 112, which is arranged adjacent to the combustion chamber at the tip of the fuel injector 1. The distributor groove 112 branches from the longitudinal channel 111 into a first distributor groove 112a and a second distributor groove 112b, which are both in relation to one another

lead away from the longitudinal channel 111 opposite circumferential direction. The longitudinal web 116 prevents diametrically opposite the longitudinal channel 111 a re-merging of the two distribution grooves 112a, 112b. Instead, lead from the two Verteilernuten 112a, 112b a variety of

Flow channels 200 upwards, ie in the axial direction away from the combustion chamber. The plurality of flow channels 200 reunite in the collector groove 113, which can extend over the entire circumference of the cooling group 100. From the collector groove 113, the outlet channel 32 leads off, which again leads the coolant out of the cooling group 100, for example, back into the nozzle retaining nut 6.

The present construction of the fuel injector 1 thus uses a cooling group 100 with a cooling ring 101 for cooling the nozzle body 5, which has a very large effective cooling surface and thus significantly improves the heat flow from the nozzle body 5 into the coolant. The cooling group 100 consists of a heat sink 102, which with its transfer surface 102d on

Outer circumference of the nozzle body 5 is applied, a cooling ring 101, which has a large cooling surface for the. Through the plurality of flow channels 200

Heat exchange provides, and from a cooling sleeve 103, which takes over the media-tight seal to the outside. In the solution shown in Figure 4, the flow channels 200 of the cooling ring 101 are flowed through in parallel, but depending on the design, a sequential flow is possible, for example, by the flow channels 200 are strung together winding shape. The flow channels 200 may, for example, also have a meandering shape for this purpose.

To simplify the construction of the fuel injector, the number of parts of the cooling group 100 can be reduced in further developments of the invention by integrating the geometry of the cooling ring 101 into cooling sleeve 103 or heat sink 102. Depending on the required cooling effect, the complexity of the

Flow channels 200 are adjusted. Even a one-piece cooling group 100 is possible when using the 3D printing process as a manufacturing process for the cooling group 100. The flow can also be done in parallel or sequential in these variants. The design of the flow channel geometry is thus almost arbitrary.

The cooling group 100 with the flow channels 200 formed therein is also suitable as a retrofit kit for existing fuel injectors 1 without active cooling.

Claims

claims

1. Fuel injector (1) for injecting fuel into the combustion chamber of an internal combustion engine, wherein the fuel injector (1) comprises a nozzle body (5), wherein in the nozzle body (5) a pressure chamber (8) is formed, which via an inlet bore (13 ) is supplied with pressurized fuel, wherein a at least one injection opening (9) releasing or closing longitudinally movable nozzle needle (7) in the pressure chamber (8) is arranged, wherein a cooling group (100) the nozzle body (5) is arranged at least partially surrounding .

characterized,

the cooling group (100) comprises a cooling ring (101) which delimits a multiplicity, preferably more than 20, flow-through flow channels (200) through which the nozzle body (5) can be cooled.

2. Fuel injector (1) according to claim 1,

characterized,

a longitudinal channel (111) and a distributor groove (112) are formed in the cooling group (100), the distributor groove (112) running close to the combustion chamber over almost the entire circumference of the cooling group (110) and the longitudinal channel (111) supplying the distributor groove ( 112) with coolant.

3. Fuel injector (1) according to claim 2,

characterized,

that the distributor groove (112) in the circumferential direction by a at the

Cooling group (100) arranged longitudinal ridge (116) is limited.

4. Fuel injector (1) according to claim 2 or 3,

characterized,

the flow channels (200) branch off from the distributor groove (112) and extend in a direction away from the combustion chamber.

5. Fuel injector (1) according to claim 3,

characterized, in that a collector groove (113), into which the flow channels (200) open, is formed in the cooling group (100).

6. Fuel injector (1) according to claim 5,

characterized,

in that the nozzle body (5) is clamped to the fuel injector (1) by means of a nozzle clamping nut (6) and supply channels (30) for supplying and discharging the coolant into and out of the cooling group (100) are formed in the nozzle retaining nut (6) wherein a first supply channel (30a) is hydraulically connected to the longitudinal channel (111), and wherein a second supply channel (30b) is hydraulically connected to the collector groove (113).

7. Fuel injector (1) according to one of claims 1 to 6,

characterized,

the flow channels (200) extend parallel in an axial direction of the cooling group (100).

8. Fuel injector (1) according to one of claims 1 to 6,

characterized,

the flow channels (200) meander.

9. Fuel injector (1) according to one of claims 1 to 8,

characterized,

in that the cooling group (100) comprises a cooling body (102) on which an inner transfer surface (102d) is formed, which cooperates with an outer surface of the nozzle body (5).

10. Fuel injector (1) according to claim 9,

characterized,

that the longitudinal channel (111) between the cooling ring (101) and the

Heat sink (102) is formed.

11. Fuel injector (1) according to one of claims 1 to 10,

characterized, the cooling group (100) comprises a cooling sleeve (103) which seals the cooling group (100) to the environment in a media-tight manner.

12. Fuel injector (1) according to claim 11,

characterized,

the flow channels (200) are formed between the cooling ring (101) and the cooling sleeve (103).

13. Fuel injector (1) according to one of claims 1 to 12,

characterized,

the cooling group (100) is formed in one piece by means of a 3D printing method.