WO2021078447A1

WO2021078447A1 - Internally pressurized component, in particular for fuel injection in an internal combustion engine

Info

Publication number: WO2021078447A1
Application number: PCT/EP2020/076138
Authority: WO
Inventors: Giovanni Ferraro; Dietmar Uhlmann; Aitor Echaniz
Original assignee: Robert Bosch Gmbh
Priority date: 2019-10-21
Filing date: 2020-09-18
Publication date: 2021-04-29
Also published as: DE102019216166A1

Abstract

The invention relates to an internally pressurized component, comprising a vertical inflow channel (1) and at least one horizontal connection channel (2, 3) branching off transversely from the inflow channel, which channels jointly form an intersection region (4) having an elliptical cross-section. The connection channel (2; 3) runs at an acute angle (α) to a connection-channel-proximal axis of symmetry (S) of the cross-section of the inflow channel (1). The cross-section of the inflow channel (1) and the cross-section of the connection channel (2; 3) are elliptical in the intersection region (4). The major axis (x_A) of the cross-section of the connection channel (3) runs, in the intersection region (4), at an angle (α) to the major axis (x_Z) of the cross-section of the inflow channel (1).

Description

description

Title:

Internal pressure-loaded component, especially for fuel injection in an internal combustion engine

The present invention relates to an internal pressure-loaded component, in particular for fuel injection in an internal combustion engine, with a vertical inflow channel and at least one horizontal connection channel branching off transversely therefrom, which together form an intersection area with an elliptical cross-section, the connection channel at an acute angle a with respect to an axis of symmetry close to the connection channel the cross section of the inflow channel runs.

The field of application of the present invention extends primarily to fuel injection systems of motor vehicles, in particular to so-called common rail systems. The fuel-carrying components of such fuel injection systems are under a very high internal pressure of usually up to 1600 bar. In addition, the internal pressure is also subject to strong periodic fluctuations, so that the component of interest here is subject to correspondingly high strength requirements.

State of the art

EP 1 435 454 A1 discloses a generic component subject to internal pressure. This has a vertical inflow channel for connection to a high-pressure fuel reservoir and a horizontal connection channel branching off transversely therefrom for connecting an injector or the like. The horizontal connection channel opens into the inflow channel at an acute angle formed with respect to a connection channel-side symmetry axis S and the axis of the connection channel, so that in the Intersection area results in an elliptical cross section. The cross section of the inflow channel is elongated in the intersection area and the confluence of the connecting channel takes place on a straight side section of the inflow channel, which is elongated in cross section. According to other disclosed cross-sectional shapes, the inflow channel can also have a rectangular or circular cross-section. By designing the intersection area as an ellipse, which results here from the acute-angled oblique feed of the connection channel, which is circular in cross-section, the stresses in these local areas can be reduced, which means that the permissible internal pressure itself can also be increased.

According to the generally known prior art, similar internal pressure-loaded components of fuel injection systems are used in which two horizontal connection channels open into a vertical inflow channel, without a bore offset or an inclined position of the connection channel. In addition to the connections for the inflow channel and the two connection channels, such a component usually has a further pressure sensor connection assigned to the inflow channel. On the input side, however, the inflow channel is connected to a high-pressure pump and the connection channels form injector connections.

Under internal pressure, the highest component stress also occurs here in the intersection area of the channels. The geometries of the continuously circular cross-sectional channels are due to manufacturing technology, since they are produced by conventional machining. The construction is also optimized for a minimum use of material with sufficient strength.

It is the object of the present invention to further improve an internal pressure-loaded component of the generic type in such a way that the duct routing can be changed by overcoming the previously existing manufacturing restrictions in such a way that local stress maxima in the intersection area are further reduced in order to further reduce the use of material. Disclosure of the invention

The object is achieved on the basis of an internal pressure-loaded component according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims reproduce advantageous developments of the invention.

The invention includes the technical teaching that the cross section of the inflow channel and the cross section of the at least one connection channel of an internal pressure-loaded component in the intersection area are elliptical, the main axis X _{A of} the cross section of the connection channel in the intersection area at the angle a to the main axis xz of the cross section of the Inflow channel runs.

The channel geometry according to the invention can be realized through the use of new manufacturing technologies - in particular metal powder 3D printing - whereby the constructional restrictions of the previously customary machining or shape-related manufacturing methods can be overcome. The channel design according to the invention causes a reduction in the component stress level of approx. 50% compared to the channel design according to the prior art described at the beginning, so that dimensions can be made with correspondingly smaller wall thicknesses, which contributes to further material savings.

The edges formed in the intersection area should preferably also be rounded, with the edges being rounded with a radius R in the range from 1 to 1.5 mm, preferably 1.2 mm, for the purpose of the invention. In this respect, the stress reduction according to the invention is further improved by the sum of the measures of a confluence of two elliptical channel cross-sections with an oblique drilling at the acute angle α and an additional local rounding of the edges occurring in the intersection area. According to a further measure improving the invention, it is proposed that the cross-sectional shape of the inflow channel and / or of the connection channel change from circle to ellipse in the direction of the intersection area. This means that there is the elliptical cross section according to the invention in the intersection area, whereas the external connections on the component have a conventional circular cross section to accommodate a screw connection or the like. As a result, the conventional connection configuration of the component can continue to be used despite the channel design that has been changed according to the invention.

According to a preferred embodiment, it is provided that the cross section of the connection _{channel widens conically in the direction of the intersection area with respect to the main axis X A} , and that the cross section of the connection channel tapers conically in the direction of the intersection area with respect to the transverse axis Y _A. The longer semiaxis of the ellipse is understood as the main axis, whereas the shorter semiaxis of the ellipse is referred to here as the transverse axis. With regard to the connection channel, this results in a channel geometry which, starting from the connection-side circular cross section, is compressed with respect to the transverse axis and is enlarged with respect to the main axis. The resulting increasing flattening of the connection channel in the direction of the intersection area leads to a significant increase in strength in the intersection area.

According to the preferred embodiment, it is proposed with regard to the channel design of the inflow channel that its cross section in the direction of the intersection area remains the same with respect to the main axis, whereas the cross section of the inflow channel tapers conically in the direction of the intersection area with respect to the transverse axis. In other words, in the vertical inflow channel, the longer semiaxis of the ellipse remains unchanged in the course direction, whereas the shorter semiaxis of the ellipse, ie the transverse axis, is compressed and thus flattened. This geometric measure also makes a contribution to increasing the strength of the intersection area of the component. With regard to the channel geometry, it is also proposed that the length LE of the section of the conically widening or tapering elliptical cross section of the connection channel and / or the inflow channel is 1.5 to 2 times the circular cross section of the connection channel or the inflow channel. This longitudinal course also makes a contribution to increasing the strength of the component in the intersection area while at the same time reducing the amount of material used, since the required channel length significantly influences the amount of material to be used for the component.

It is further proposed that the conical course of the connection channel merges tangentially into the elliptical cross section of the inflow channel at a meeting point T in the mouth area. This creates an edge-free transition, at least in some areas, which does not offer any point of attack for component stresses. In this context, it is further proposed that outside the tangential transition at the meeting point T, the opening area of the connection channel and inflow channel is provided with the aforementioned rounding. In particular, a radius of 1.2 mm has proven to be advantageous for the dimensional ratios and pressure ratios of the field of application according to the invention, that is to say it significantly minimizes component stress.

In this context, the acute angle a at which the smaller cross section of the connection channel enters the larger cross section of the inflow channel should be in the range between 3 to 6 °, preferably 4.4 °. The latter value has proven to be particularly advantageous for the application subject of the invention, that is to say it significantly minimizes component stress.

According to the preferred embodiment of the invention, it is further proposed that exactly two horizontal connection channels are connected to the vertical inflow channel, whereby the two connection channels should open opposite one another and at the same height into the inflow channel in order to achieve a stress-optimized and material-saving overall shape. Further measures improving the invention are specified in the dependent claims or are shown in more detail below together with the description of a preferred exemplary embodiment of the invention with reference to the figures. It shows:

1 shows a partially transparent perspective view of a component subjected to internal pressure for the connection of injectors of a common rail injection system,

FIG. 2 is a plan view of the component according to FIG. 1,

3 shows a side view of the component according to FIG. 1,

FIG. 4 shows a detailed representation around the intersection area of the component in the side view according to FIG. 3,

FIG. 5 shows a cross section of the component according to FIG. 1 at the level of the connection channels, and FIG

6 shows a longitudinal section of the component according to FIG. 1 through the inflow channel.

According to FIG. 1, an internal pressure-loaded component produced by metal powder 3D printing for connecting two injectors of a common rail system of a fuel injection system (not shown here) comprises a vertical inflow channel 1 connected to a high-pressure pump (also not shown here) from from which two horizontal connection channels 2 and 3 branch off at the same height in the opposite direction. The connection channels 2 and 3 together with the inflow channel 1 each form an intersection area 4 with an elliptical cross section.

The following describes the geometric relationships with respect to the connection channel 2 or the connection channel 3, which, however, apply analogously to the respective other connection channel 3 or 2. As can be seen from FIG. 2, the connection channel 2 also does not run straight, but rather at an acute angle a with respect to an axis of symmetry S of the cross section of the inflow channel 1 that is close to the connection channel.

As becomes clear in further connection with FIG. 3, the cross section of the inflow channel 1 and the cross section of the connection channel 2 in the intersection area 4 are elliptical. The cross-sectional shape of the inflow channel 1 and the connection channel 2 changes in the direction of the intersection area 4 from a circle to an ellipse.

With regard to the detailed view according to FIG. 4 and the associated symbols, the cross section of the connection channel 2 tapers conically _{in the direction of the intersection area 4 with respect to the transverse axis y A.} This causes an increasing compression of the channel cross-section from the circular shape on the connection side to a flattened elliptical shape on the mouth side, which takes place in sections over the length sections Li and L2.

The cross section of the inflow channel 1 also tapers conically in the direction of the intersection area 4 with respect to the transverse axis yz. The total length LE of the section of the conically tapering elliptical cross section of the inflow channel 1 is 1.5 to 2.0 times the circular cross section of the inflow channel 1. The same applies analogously to the connection channel 2. Furthermore, the mouth area of the connection channel 2 and 3 on the inflow channel 1 provided with a rounding, the radius R of which is 1.2 mm.

From the cross section according to FIG. 5 it can be seen that the cross section of the connection channel 3 widens conically _{in the direction of the intersection area 4 with respect to the main axis X A.} Of course, the same applies analogously with regard to the opposite connection channel 2. In contrast, the cross section of the inflow channel 1 in the direction of the intersection area 4 remains the same with respect to the main axis xz. Furthermore, the axis of symmetry S of the cross section of the inflow channel 1, which is close to the connection channel, forms an acute angle a with the longitudinal axis of the connection channel 3, which of course also applies analogously to the opposite connection channel 2. The same acute angle a is also found due to the geometric alternating angle relationships between the main axis X _{A of} the cross section of the connection channel 3 in the intersection area 4 and the main axis xz of the cross section of the inflow channel 1 again.

With regard to the length configuration of the connection channel 3, it runs circularly in the section Lo and begins _{to become elliptical in the sections Li to L 3} , up to a compressed ellipse, as described above. The conical shape of the connecting channel 3 merges tangentially into the elliptical cross section of the inflow channel 1 at a meeting point T in the area of the mouth of the inflow channel 1.

According to FIG. 6, the total length of the inflow channel 1 comprises a length section Lo with a circular cross section, which is followed by a length section Li with an increasingly elliptical cross section in the direction of the mouth.

The invention is not restricted to the preferred exemplary embodiment described above. Rather, treatises thereof are also conceivable, which are also covered by the scope of protection of the following claims. It is also possible, for example, for only a single connection channel to branch off from an inflow channel on an internal pressure-loaded component of the type of interest here in order to forward or distribute a medium under high pressure to a consumer.

Claims

Expectations

1. Internal pressure-loaded component with a vertical inflow channel (1) and at least one horizontal connection channel (2, 3) branching off transversely therefrom, which together form an intersection area (4) with an elliptical cross-section, the connection channel (2; 3) at an acute angle ( a) runs opposite an axis of symmetry (S) of the cross section of the inflow channel (1) close to the connection channel, characterized in that the cross section of the inflow channel (1) and the cross section of the connection channel (2; 3) in the intersection area (4) are elliptical, the Main axis (XA) of the cross section of the connection channel (3) in the intersection area (4) runs at the angle (a) to the main axis (xz) of the cross section of the inflow channel (1).

2. Component according to claim 1, characterized in that the cross-sectional shape of the inflow channel (1) and / or of the connection channel (2; 3) changes from circle to ellipse in the direction of the intersection area (4).

3. Component according to claim 1, characterized in that the cross section of the connection channel (2; 3) widens conically in the direction of the intersection area (4) with respect to the main axis (XA), and that the cross section of the connection channel (2; 3) in the direction Intersection area (4) tapers conically with respect to the transverse axis (Y _A).

4. Component according to claim 1, characterized in that the cross section of the inflow channel (1) in the direction of the intersection area (4) with respect to the main axis (xz) remains the same, and that the cross section of the inflow channel (1) in the direction of the intersection area (4) with respect to the transverse axis (y _z ) tapers conically. 5. Component according to claim 3 and 4, characterized in that the length (LE) of the section of the conically widening or tapering elliptical cross section of the connection channel (2; 3) and / or of the inflow channel (1) the 1,

5 to 2 times the circular cross-section of the connection channel (2; 3) or the inflow channel (1).

6. Component according to claim 3 and 4, characterized in that the conical course of the connection channel (2; 3) merges tangentially into the elliptical cross section of the inflow channel (1) at a meeting point (T) in the mouth area.

7. Component according to claim 7, characterized in that the mouth area of the connection channel (2;

3) and inflow channel (1) outside the tangential transition at the meeting point (T) is provided with a rounding, the radius (R) of which is in the range from 1 to 1.5 millimeters.

8. Component according to claim 1, characterized in that the acute angle (a) at which the smaller cross section of the connection channel (2; 3) enters the larger cross section of the inflow channel (1) is in the range between 3 to 6 °.

9. Component according to claim 1, characterized in that two oppositely arranged connection channels (2, 3) open into the inflow channel (1) at the same height.

10. Component according to claim 1, characterized in that the length of the main axes (XA, x _z ) and the transverse axes (U _A, U _Z ) of the connection channel (2; 3) or the inflow channel (1) in the elliptical intersection area (4) each corresponds to half the diameter of the ellipses.