WO2018059809A1 - Retaining body for a fuel injector, fuel injector having a retaining body and method for producing a retaining body - Google Patents

Abstract

The invention relates to an elongated retaining body (1) for a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, wherein a recess (2) extending in the longitudinal direction and for receiving an actuator module (12) and/or a coupler module, as well as a high-pressure channel (3) extending in the longitudinal direction are formed in the retaining body (1) and arranged next to one another. According to the invention, at least one additional channel extending in the longitudinal direction and for forming a storage volume (4, 5) is formed in the retaining body (1), which is connected to the high-pressure channel (3). The invention also relates to a fuel injector having a retaining body (1) of this type and a method for producing the retaining body (1) according to the invention.

Description

 description

title

 Holding body for a fuel injector, fuel injector with holding body and method for producing a holding body

The invention relates to a holding body for a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine with the features of the preamble of claim 1. Furthermore, the invention relates to a fuel injector with such a holding body and a method for producing the holding body.

State of the art

A fuel injector of the type mentioned above is exemplified in the published patent application DE 10 2006 051 583 Al. This has a preferably needle-shaped injection valve member which can be actuated via an actuator. During actuation, in particular during the execution of rapid successive multiple injections, pressure oscillations may occur in the fuel injector which may adversely affect the closing operation of the fuel injection valve. This can lead to undesirable effects in the combustion process and / or increased wear on the mechanical components of the fuel injector. For damping of pressure oscillations, therefore, a storage volume is proposed which is formed in addition to an actuator space for receiving the actuator and a nozzle chamber for receiving the injection valve member in a separate storage element. The storage segment is preferably arranged between a nozzle body and a throttle plate and clamped axially with the latter via a nozzle tension nut. The size of the additional storage volume can be varied over the length of the storage segment without changing the injector diameter. The connection to the nozzle chamber, which is often the place of origin of the pressure oscillations, takes place via a damper throttle point. Based on the above-mentioned prior art, the present invention seeks to provide an additional storage volume for damping pressure oscillations in a fuel injector while maintaining a compact design. Furthermore, the measures to create the additional storage volume should be simple and inexpensive to implement.

To achieve the object, a holding body for a fuel injector with the features of claim 1, a fuel injector with the features of claim 9 and a method for producing a holding body with the features of claim 10 are proposed. Advantageous developments of the invention can be found in the respective subclaims.

Disclosure of the invention

Proposed is a holding body for a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, which has an elongated shape and in which a longitudinally extending recess for receiving an actuator module and / or a coupler module and a longitudinally extending high-pressure channel are formed, which are arranged side by side. According to the invention, at least one additional channel extending in the longitudinal direction is formed in the holding body to form a storage volume which is connected to the high-pressure channel.

The storage volume forms an additional volume which, due to the connection to the high-pressure channel, is suitable for damping pressure pulsations in the fuel injector. The pressure pulsations may be due to injection processes and / or by the delivery characteristics of an upstream high-pressure fuel pump. Further, the additional storage volume reduces the risk of a pressure drop at the beginning of an injection, since a fast dosing of fuel is ensured. The resulting high injection pressure improves the atomization of the fuel during injection and, as a result, the combustion of fuel in the combustion chamber. Due to the adjacent arrangement of recess and high-pressure channel, the holding body has different strong wall cross sections. This is especially true when the recess is arranged off-center to simplify the lateral arrangement of the high-pressure channel. Between the recess and the high-pressure channel then gland-like wall cross sections with comparatively large wall thickness, in the area which preferably the additional storage volume is formed. In this way, the outer dimensions of the holding body remain unchanged. At the same time a weight reduction is achieved.

Ideally, the holding body has been produced in an additive manufacturing process, in particular in a 3D printing process. This allows the realization of arbitrarily shaped cavities in the holding body, so that the available space can be used optimally. Furthermore, can be dispensed with a multi-part design of the holding body to form the storage volume. This eliminates the step of joining, so that the production is significantly simplified. Sealing measures are also not required.

The 3D printing also requires minimal use of materials, so that further costs can be saved here. The material can also be specifically selected depending on the required nominal pressure.

Preferably, the storage volume is connected via at least one throttle point to the high pressure passage. If pressure oscillations occur in the high-pressure channel, they pass through the throttle point into the storage volume, kinetic energy being converted into heat in the region of the throttle point, so that the desired damping effect occurs. Advantageously, the storage volume is repeatedly connected to the high-pressure channel. The multiple connection allows, if necessary, a fast venting and / or emptying of the storage volume.

Furthermore, the channel forming the storage volume preferably has a cross-sectional shape deviating from the circular shape. By way of example, the channel can have a small-shaped cross-sectional shape in order to optimally utilize the space existing between the recess and the high-pressure channel. Preferably, the cross-sectional shape describes an arc which extends over a partial peripheral region of the extends. Furthermore, the channel may have an elliptical cross-sectional shape, so that a plurality of such channels can be arranged next to each other while optimally utilizing the available space.

According to a preferred embodiment of the invention, the storage volume is formed from a channel which extends substantially meander-shaped and has a plurality of adjacent sections, wherein preferably two adjacent sections are connected via an arc. In this way, the cross section of the holding body is hardly weakened by the additional storage volume, so that it has a high compressive strength. Preferably, the channel has three adjacent sections, of which two sections defining the one beginning and one end of the channel are each connected to the high-pressure channel. In this way, the channel can be flushed over its entire length. The adjacent channel sections preferably have an elliptical cross-sectional shape, so that a sufficient distance between the sections can be maintained for the voltage-optimized design of the holding body.

In a development of the invention, it is proposed that the arc forms an omega-shaped loop. This has the advantage over a U-shaped arc that additional storage volume is generated. Further preferably, the omega-shaped loop - viewed in cross section of the holding body - additionally bent in the circumferential direction, so that it nestles around the recess of the holding body.

Advantageously, at least two storage volumes are formed in the holding body, which are arranged symmetrically in cross-section of the holding body with respect to the recess and / or the high-pressure channel. The symmetrical arrangement of the storage volumes leads to a uniform as possible pressure load of the high pressure body. In addition, the storage volume can be maximized in this way.

In addition, it is proposed that the high-pressure channel has at least one spherical intersection region widening the cross-section for connecting a storage volume. The connection is preferably via a throttle point, which can be realized by a channel section with a reduced diameter, the opens in the spherical intersection region in the high-pressure channel. In this way, transitions can be rounded and thus flow-optimized.

Advantageously, a return channel is formed in the holding body, which is used for returning a leakage and / or Absteuermenge. Preferably, the return channel is connected to the recess for receiving the actuator and / or coupler module, so that the return channel does not have to be performed over the entire length of the high pressure body. For example, an annular space remaining between the actuator and / or coupler module and the holding body can be used within the recess as a return channel. Since the return channel preferably also extends in the longitudinal direction, the connection of the return channel to the recess is preferably realized via a connecting channel, which may extend, for example, transversely to the return channel.

Since the holding body described above is preferably used in a fuel injector, a fuel injector is proposed with a holding body according to the invention further. In this case, an actuator module and / or a coupler module is or are received in the recess of the holding body.

Furthermore, a method for producing the holding body according to the invention is proposed. The production of the holding body is thus carried out in an additive manufacturing process, preferably in a 3D printing process. The 3D printing process allows the realization of arbitrarily shaped cavities in the holding body, without forming this in several parts and then having to add. Furthermore, no costly sealing measures.

Furthermore, it is proposed that internal surfaces are subsequently smoothed. When smoothing, burrs and / or any loose particles can be removed. Alternatively or additionally, it is proposed that internal edges are subsequently rounded. The rounding of the edges results in a flow optimization within the connected cavities. The smoothing and / or rounding can be effected, for example, by means of pressure fluid lapping. Preferred embodiments of the invention are explained below with reference to the accompanying drawings. These show:

1 is a schematic side view of a holding body according to the invention according to a first preferred embodiment of the invention,

2 shows a schematic cross section of the holding body of Fig.l,

3 is a perspective view of the cavities formed in the holding body of FIG. 1, FIG.

4 is an enlarged detail of FIG. 3 in the form of a side view,

5 shows a schematic longitudinal section through the area of the holding body shown in FIG. 4,

6 shows a further spatial representation of the cavities formed in the holding body of FIG. 1, FIG. 7 shows a bottom view of the holding body of FIG. 1,

8 shows a schematic sectional view of a holding body according to the invention according to a second preferred embodiment of the invention, FIG. 9 shows an enlarged detail of FIG. 8, FIG.

10 is a further enlarged detail of FIG. 8,

11 shows a schematic representation of the high-pressure channel with connected storage volumes according to a third preferred embodiment of the invention,

FIG. 12 shows a schematic cross section through a holding body, which has the high-pressure channel and the storage volumes according to FIG. 11, FIG. 13 is a schematic cross section through a holding body according to the second or third preferred embodiment and

14 shows a schematic side view of an additional storage volume of a holding body according to the second or the third preferred embodiment.

Detailed description of the drawings

1 shows a holding body 1 for a fuel injector according to a first preferred embodiment of the invention. In the illustration, the holding body 1 is held "translucent" in order to allow internal cavities to be discerned.The representation of the cavities is limited to the respective boundary surfaces.

The holding body 1 of Fig. 1 has an elongated shape. The cavities formed in the holding body 1 likewise have a longitudinal extent. 2, the cavities comprise a recess 2 for accommodating an actuator and / or coupler module, a high-pressure channel 3 and two storage volumes 4, 5, which are arranged on both sides of the high-pressure channel 3 and extend around the Insert recess 2. The remaining between the cavities wall sections of the holding body 1 thus have approximately the same wall thickness, so that the strength of the holding body 1 is not substantially impaired. At the same time an additional storage volume 4, 5 is created, which serves to dampen pressure pulsations.

In addition, the holding body 1 of FIG. 1 has a return passage 10, which serves to return a leakage and / or Absteuermenge and is connected via a connecting channel 11 to the recess 2. The connection of the return channel 10 via the connecting channel 11 to the recess 2 is shown enlarged in Figures 3 and 4.

As can be seen in particular from FIG. 3, the connection of the return channel 10 to the recess 2 takes place above the storage volumes 4, 5. As a result, the space available for forming the storage volumes 4, 5 is not restricted. Furthermore, both storage volumes 4, 5 can be symmetrical with respect to maximum volume are arranged on the recess 2 and the high pressure passage 3. If, in addition, storage volume is to be generated, a storage volume 4, as shown by way of example in FIG. 1, can be extended so that it ends above the connection of the return channel 10.

The connection of the return channel 10 to the recess 2 has the advantage that the recess 2 can be used to return the leakage and / or Absteuermenge. For example, as shown in FIG. 5, an actuator module 12 can be inserted into the recess 2 in such a way that an annular space 14 remains between the actuator module 12 and the holding body 1, which is connected to the return channel 10 via the connecting channel 11. The return of the leakage and / or Absteuermenge via the annular space 14 has the advantage that a flushing of the actuator module 12 and thus improved heat dissipation is achieved. In this case, the actuator module 12 can be supported on a sloping shoulder 15 of the holding body 1 such that the annular space 14 is sealed off from a cable feedthrough 16. If required, an additional O-ring seal can be provided.

The return channel 10 facing away from the end of the holding body 1 is shown in Figs. 6 and 7. The recess 2 and the high-pressure channel 3 are led to an end face 17 of the holding body 1, while the storage volumes 4, 5 end before. The storage volumes 4, 5 thus form cavities enclosed on all sides, which are only connected via throttle points 6, 7 to the high-pressure passage 3 (see FIG. 6). For the production of such cavities, in particular, an SD printing method is suitable, so that preferably the holding body 1 has been produced in a 3D printing process.

As can be seen in particular from FIG. 7, two pin receptacles 13, which in conjunction with pins to be inserted therein (not shown), form an anti-twist device on the end face 17 of the holding body 1. Further, two semi-circular recesses 18 are formed in the end face 17, which cause an increase in the surface pressure, when the holding body 1 is clamped axially with at least one further body member. FIG. 8 shows a further preferred embodiment of a holding body 1 according to the invention. Here, an additional storage volume 4 is provided by a meandering formed channel, which is connected at its two ends in each case via a throttle point 6, 7 to the high pressure passage 3. In the area of the throttle points 6, 7, the high-pressure channel 3 has spherical intersection regions 8, 9, which allow a rounding of the transitions (see also FIGS. 9 and 10).

From the upper orifice 6, which is formed by an arcuate channel section of reduced diameter, a first section 4.1 of the channel extends down to an omega-shaped arc 4.4. From there, a second section 4.2 again leads upwards to another omega-shaped arch 4.5. From here, a third section 4.3 again leads downwards and then runs obliquely to the lower throttle point 7, which in turn is formed by a channel section with a reduced diameter. Since the omega-shaped arches 4.4, 4.5 also have a curved course in plan view, this storage volume 4 nestles around the recess 2 and the available space is used optimally.

In addition to the storage volume 4, a further storage volume 5 may be provided, which is designed in mirror image and is composed of the channel sections 5.1, 5.2 and 5.3 and the omega-shaped sheets 5.4, 5.5. The arrangement of the storage volumes 4, 5 again takes place symmetrically with respect to the recess 2 and the high-pressure channel 3. This embodiment is shown in FIG. 11, wherein the representation for the sake of simplicity on the boundary surfaces of the two storage volumes 4, 5 and the High pressure channel 3 limited. The symmetrical arrangement of the two storage volumes 4, 5 with respect to the recess 2 and the high-pressure channel 3 is shown in particular in FIG. 12. It also shows the arcuate course of the two upper omega-shaped arches 4.4 and 5.4.

Since the space for forming the adjacent channel sections of the storage volumes 4, 5 is limited, it is proposed that the sections 4.1, 4.2, 4.3 and 5.1, 5.2, 5.3 - if present - have an elliptical cross-sectional shape. On In this way, larger distances between the sections 4.1, 4.2, 4.3 and possibly 5.1, 5.2, 5.3 can be achieved, whereby the compressive strength of the holding body 1 increases.

In order to make optimal use of the available space, it is further proposed that the adjacent sections 4.1, 4.2, 4.3 and possibly 5.1, 5.2, 5.3 are different

Lengths Ii,, possess (see Fig. 14). Via the omega shape of the sheets 4.4, 4.5 and possibly 5.4, 5.5, the storage volume 4, 5 can be further maximized.

Claims

claims 1. holding body (1) for a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine, wherein the holding body (1) is elongated and in the holding body (1) has a longitudinally extending recess (2) for receiving an actuator module (12) and / or a coupler module and a longitudinally extending high pressure channel (3) are formed, which are arranged side by side, characterized in that in the holding body (1) at least one additional longitudinally extending channel for forming a storage volume (4, 5) is formed, wherein the storage volume (4, 5) is connected to the high-pressure channel (3). 2. holding body (1) according to claim 1, characterized in that the storage volume (4, 5) via at least one throttle point (6, 7) is connected to the high pressure passage (3). 3. holding body (1) according to claim 1 or 2, characterized in that the channel forming the storage volume (4, 5) has a cross-sectional shape deviating from the circular shape, the cross-sectional shape preferably describing an arc extending over a partial circumferential area of the recess (2). 4. holding body (1) according to one of the preceding claims, characterized in that the storage volume (4, 5) is formed of a channel which extends substantially meandering and a plurality, preferably three, juxtaposed sections (4.1, 4.2, 4.3, 5.1, 5.2, 5.3), preferably two in each case adjacent sections (4.1, 4.2, 4.3, 5.1, 5.2, 5.3) are connected by an arc (4.4, 4.5, 5.4, 5.5). 5. holding body (1) according to claim 4, characterized in that the arc (4.4, 4.5, 5.4, 5.5) forms an omega-shaped loop, which is preferably additionally bent in the circumferential direction in the cross section of the holding body (1). 6. holding body (1) according to one of the preceding claims, characterized in that at least two storage volumes (4, 5) in the holding body (1) are formed, which are arranged in the cross section of the holding body (1) symmetrically with respect to the recess (2) and / or the high-pressure channel (3). 7. holding body (1) according to one of the preceding claims, characterized in that the high-pressure channel (3) has at least one spherical intersection region (8, 9) widening the cross-section for connecting a storage volume (4, 5). 8. holding body (1) according to one of the preceding claims, characterized in that in the holding body (1) a return channel (10) is formed, which is preferably connected to the recess (2), wherein further preferably the connection via a connecting channel (11) is realized. 9. Fuel injector with a holding body according to one of the preceding claims, wherein in the recess (2) an actuator module (12) and / or a coupler module is received or are. 10. A method for producing a holding body (1) for a fuel! Ajector according to one of claims 1 to 8, characterized in that the holding body (1) is produced in an additive manufacturing process, preferably in a 3D printing process. 11. The method according to claim 10, characterized in that internal surfaces are subsequently smoothed and / or inner edges are subsequently rounded, wherein preferably the smoothing and / or rounding is effected by means of Druckfließläppen.