EP3156640A1

EP3156640A1 - Nozzle body for a fluid injector and fluid injector

Info

Publication number: EP3156640A1
Application number: EP15189685.9A
Authority: EP
Inventors: Antonio Agresta; Luca Gestri; Sara Vongher
Original assignee: Continental Automotive GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2015-10-14
Filing date: 2015-10-14
Publication date: 2017-04-19
Anticipated expiration: 2035-10-14
Also published as: EP3156640B1

Abstract

A nozzle body (1) for a fluid injector (30) comprises a nozzle wall (3), an opening (5), a longitudinal axis (L) and a fluid inlet end (21) as well as a fluid outlet end (22). The nozzle body (1) further comprises a needle seat (7) and a flow hole (17) which penetrates the nozzle wall (3) in the region of the fluid outlet end (22) from the opening (5) to outside of the nozzle body (1). A sac volume portion (9) of the nozzle wall (3) is formed between the needle seat (7) and the flow hole (17) with respect to the longitudinal axis (L) and limits a cavity (10) to generate a stagnating flow area for a streaming fluid.

Description

The invention relates to a nozzle body for a fluid injector and a fluid injector.
Injectors are in widespread use, in particular for internal combustion engines where they may be arranged in order to dose a fluid into an intake manifold of the internal combustion engine or directly into a combustion chamber of a cylinder of the internal combustion engine.
In order to enable a beneficial combustion process it is necessary to provide good spray quality and fluid penetration of a fluid into the combustion chamber, amongst others. During an operation of a fluid injector, flow separation of the fluid may occur due to geometry conditions inside the fluid injector. Such a flow separation can lead to changes of streaming characteristics and may result in flow oscillations which negatively affects the spray stability and quality.
One object of the invention is to create a nozzle body for a fluid injector and a corresponding fluid injector which facilitate a reliable dosing of fluid with enhanced spray stability.
The object is achieved by the features of the independent claims. Advantageous embodiments of the invention are given in the subclaims.
According to a first aspect of the invention, a nozzle body for a fluid injector comprises a nozzle wall which limits the penetrating opening of the nozzle body along a longitudinal axis from a fluid inlet and to a fluid outlet end of the nozzle body. The nozzle body further comprises a needle seat formed as a portion of the nozzle wall to interact with a needle to prevent a fluid flow through a flow hole in a closed position and otherwise to enable it. The flow hole penetrates the nozzle wall in the region of the fluid outlet end from the opening to outside of the nozzle body. The nozzle body further comprises a sac volume portion of the nozzle wall formed in the region of the fluid outlet end such as to limit a sac volume. The sac volume portion limits a cavity between the needle seat and the flow hole with respect to the longitudinal axis to generate a stagnating flow area for a streaming fluid.
Such a configuration of a nozzle body for a fluid injector enables beneficial streaming conditions for a streaming fluid and contributes to enhanced spray quality of the fluid and a profitable combustion process. Due to the cavity which is realized as an additional volume in the region of the sac volume, the spray quality of fluid out of the nozzle body is advantageously affected. This implies an improvement of spray stability due to stabilization of upstream flow conditions and a reduction of shot-to-shot deviations due to reduction of flow fluctuations or oscillations inside the needle seat area and the flow hole. The cavity realizes a stagnating flow area which represents a chamber, in which a part of the streaming fluid is temporarily stagnating and therefore affecting the streaming characteristics inside the nozzle body.
The nozzle body comprising the cavity counteracts a flow separation of the fluid which may occur due to edges of an inner geometry of the nozzle body where the fluid cannot further follow the nozzle wall. Such a flow separation leads to changes of the flow regime from potential to turbulent and may influence the streaming and spray behavior of the fluid negatively. But the additional cavity contributes to stabilized flow separation and flow conditions through the effect of a stagnating flow chamber positioned inside the separation area between the needle seat and the flow hole inlet. The described nozzle body further enables an increment of spray controllability through the changes of common nozzle design in accordance with customer requirements.
According to one embodiment of the nozzle body the sac volume portion comprises a section shaped to limit a ring-shaped notch forming the cavity.
The cavity may be formed as a half ring adjacent to the needle seat and rotationally symmetric surrounding the longitudinal axis. Regarding a cross section along the longitudinal axis the notch comprises a circular shape. Such a geometry of the cavity represents one possibility to generate a stagnating flow area which enables stabilized streaming characteristics and beneficially affects the spray quality of the escaping fluid.
Generally, the dimension of the cavity has to be big enough to generate the stagnating flow area to dissipate energy of the turbulent streaming fluid and to contribute to stabilized streaming conditions. The positioning of the cavity also affects the streaming conditions and can be optimized based on requirements for spray targeting and penetration out of the nozzle body into a combustion chamber, for example. Amongst others, the geometry of the cavity and its relative position with respect to the needle seat and the one or more flow holes have to be adapted to the respective position and geometry of the needle seat and the flow hole as well as the flow hole drilling configuration.
According to a further embodiment of the nozzle body, the sac volume portion comprises a protrusion in the region of the cavity. Such a protrusion can be realized as a protruding edge and may advantageously influence the streaming conditions inside the nozzle body in the area of the sac volume and the fluid outlet end.
According to a further embodiment with respect a cross section along the longitudinal axis the notch comprises a linear shape adjacent to a circular shape. Such a geometry of the sac volume portion and the shape of the cavity gives one possibility to realize the protrusion as mentioned above.
According to a further embodiment with respect to a direction from the fluid inlet end to the fluid outlet end and with respect to a cross section along the longitudinal axis the notch comprises a circular shape with a predetermined radius radially extending from the longitudinal axis.
According to a further embodiment of the nozzle body with respect to a direction from the fluid inlet end to the fluid outlet end and with respect to a cross section along the longitudinal axis the notch comprises a circular shape having a predetermined radius radially extending from the longitudinal axis and a linear shape having a predetermined length extending parallel to the longitudinal axis.
According to a further embodiment of the nozzle body with respect to a direction from the fluid inlet end to the fluid outlet end and with respect to a cross section along the longitudinal axis the notch comprises a linear shape having a predetermined height extending parallel to the longitudinal axis, a linear shape having a predetermined length extending perpendicular to the longitudinal axis, a circular shape having a predetermined radius radially extending from the longitudinal axis and a linear shape having a predetermined length extending parallel to the longitudinal axis.
Such configurations of the nozzle body enables specific re-alizations of the cavity geometry formed by the sac volume portion as a portion of the nozzle wall. Such geometries advantageously affect the streaming conditions of a streaming fluid and counteract the effect of flow separation which adversely affects the spray quality.
According to a second aspect of the invention a fluid injector comprises a nozzle body in accordance with one of the embodiments described above and a needle which is arranged axially movable in the opening of the nozzle body with respect to the longitudinal axis to prevent a fluid flow through the fluid hole in a closed position and otherwise to enable it.
Such a fluid injector enables enhanced performance especially concerning improved streaming conditions of a streaming fluid with beneficial spray stability and controllability as well as penetration characteristics into a combustion chamber, for instances. Because the fluid injector comprises one embodiment of the nozzle body all characteristics and features corresponding of the nozzle body as described above also relates to the fluid injector and vice versa.
Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings and reference numbers. Identical reference numbers designate elements or components with identical functions. The figures show:

Figures 1A-1C: an exemplary embodiment of a nozzle body for a fluid injector;
Figures 2A-2C: a further exemplary embodiment of the nozzle body for a fluid injector;
Figure 3: exemplary embodiments of a cavity formed by a sac volume portion of the nozzle body;
Figures 4A-4B: streaming conditions for different sac volume portions;
Figures 5A-5B: further illustration of streaming conditions for different sac volume portions.

Figures 1A to 1C illustrate a respective cross section of an exemplary embodiment of a nozzle body 1 for a fluid injector 30 in different views. Figure 1A shows an overview of the nozzle body 1 whereas Figures 1B and 1C illustrate details of the nozzle body 1 in respective enlarged views.
The nozzle body 1 comprises a nozzle wall 3 (just illustrated as a line) which limits a penetrating opening 5 of the nozzle body 1. The nozzle wall 3 comprises a needle seat 7 and a sac volume portion 9 adjacent to the needle seat 7 with respect to a longitudinal axis L. With respect to the illustrated cross section along the longitudinal axis L the sac volume portion 9 can be named as sac volume contour 9 as well. The needle seat 7 and the sac volume contour 9 are arranged at a fluid outlet end 22 of the nozzle body 1 whereas a fluid inlet end 21 is located at an opposite side of the nozzle body 1 with respect to the longitudinal axis L. The nozzle body 1 is configured rotationally symmetric with respect to the longitudinal axis L, for example.
Further, a needle 32 is arranged axially movable in the opening 5 of the nozzle body 1 to interact with the needle seat 7 to prevent a fluid flow through a flow hole 17 in a closed position and otherwise to enable it. The flow hole 17 penetrates the nozzle wall 3 in the region of the fluid outlet end 22 from the opening 5 to outside of the nozzle body 1 for dosing fluid into a combustion chamber, for example. The nozzle body 1 may comprise one or more further flow holes 17 for dosing a given amount of fluid. Regarding the illustrated embodiments flow hole 17 as shown substantially represents a channel through the nozzle wall 3.
Regarding the enlarged views of the fluid outlet end 22 and the nozzle tip it is apparent that the sac volume contour 9 is directly adjacent to the needle seat 7 and comprises a circular-shaped notch 15 with respect to a cross section along the longitudinal axis L. Therefore, the notch 15 comprises a circular shape 12 (Figure 1B and 1C) . The sac volume contour 9 or the notch 15 limits a cavity 10 between the needle seat 7 and the flow hole 17 with respect to the longitudinal axis L to generate a stagnating flow area for a streaming fluid. With respect to the nozzle body 1 as a whole the notch 15 is ring-shaped and rotationally symmetric surrounding the longitudinal axis L forming a cavity 10.
Due to the cavity 10 the nozzle body 1 and the corresponding fluid injector 30 enable beneficial streaming conditions for a streaming fluid and contribute to enhanced spray quality of the fluid with respect to a profitable combustion process. The cavity 10 realizes an additional volume in the region of the sac volume 11 and selectively increases the sac volume 11 such that the spray quality of fluid out of the nozzle body 1 is advantageously affected. This implies an improvement of spray stability due to stabilization of upstream flow conditions and a reduction of shot-to-shot deviations due to reduction of flow fluctuations and flow oscillations inside the area of needle seat 9 and the flow hole 17.
The cavity 10 of the nozzle body 1 counteracts a flow separation of the fluid which may occur due to edges of the inner geometry of the nozzle body 1 where the fluid cannot further follow the nozzle wall 3. Such a flow separation leads to changes of the flow regime and may influence the streaming and spray behavior of the fluid negatively. But the additional cavity 10 counteract the adverse effects of the flow separation and contributes to stabilized flow conditions through the effect of a stagnating flow chamber positioned inside the separation area between the needle seat 7 and the inlet of the flow hole 17. The illustrated nozzle body 1 further enables an increment of spray controllability.
The cavity 10 forms a ring shape between the needle seat 7 and the flow hole 17 surrounding the longitudinal axis L. Such a geometry of the cavity 10 represents one possibility to generate a stagnating flow area which enables stabilized streaming characteristics and beneficially affects the spray quality of the escaping fluid.
Figures 2A to 2C illustrate a further exemplary embodiment of the nozzle body 1 and the fluid injector 30 in respective cross sections. Figure 2A shows an overview of the nozzle body 1 whereas Figures 2B and 2C illustrate details of the nozzle body 1 in respective enlarged views.
In comparison to the described embodiment of Figures 1A to 1C the sac volume contour 9 of this embodiment comprises a protrusion 14 to realize a beneficial stagnating flow area for the streaming fluid and to enhance spray controllability of the escaping fluid. The cavity 10 is formed by one portion of the nozzle wall 3 and in particular by one portion of the sac volume contour 9 and comprises a circular shape 12 and a linear shape 13 which realizes the protrusion 14 facing the flow hole 17 with respect to a substantial streaming direction.
Figure 3 illustrates three possible geometries of the cavity 10 wherein the cavity 10 comprises a circular shape 12 and additionally one or more linear shapes 13. Two exemplary embodiments are already discussed with respect to the Figures 1A to 1C and 2A to 2C. Therein the sac volume contour 9 comprises a predetermined radius R of the circular shape 12. Regarding the exemplary embodiment of Figure 2A to 2C the sac volume contour 9 further comprises a linear shape 13 with a given length L2 facing the flow hole 17 and realizing the protrusion 14.
A third possibility to realize a stagnating flow area inside the nozzle body 1 and the sac volume 11 by the cavity 10 is formed with a first linear shape 13 with a given height H2 substantially parallel to the longitudinal axis L and a second linear shape 13 with a predetermined length L1 substantially perpendicular to the first linear shape 13 and the longitudinal axis L. The sac volume 9 further comprises a circular shape 12 with a given radius R directly adjacent to the second linear shape 13 and radially extending with respect to the longitudinal axis L. The sac volume 9 further comprises a third linear shape 13 with a predetermined length L2 substantially parallel to the longitudinal axis L which forms the protrusion 14 analogously to the embodiment of Figure 2A to 2C.
Advantageously, the position and geometry of the cavity 10 can be attuned to the position and geometry of the needle seat 7 and/or the flow hole 17, for example regarding a distance D of the cavity 10 to the inlet of the flow hole 17, for optimized spray quality and penetration characteristics in accordance with customer requirements.
Generally, the dimension or volume of the cavity 10 has to be big enough to generate the stagnating flow area to dissipate energy of the streaming fluid and to contribute to stabilized streaming conditions. The positioning of the cavity 10 also affects the streaming conditions and can be optimized based on requirements for spray targeting and penetration out of the nozzle body 1 into a combustion chamber, for example. Amongst others, the geometry of the cavity 10 and its relative position with respect to the needle seat 7 and the one or more flow holes 17 have to be adapted to the respective position and geometry of the needle seat 7 and the flow hole 17 as well as drilling configurations of the flow hole 17.
Figures 4A and 4B illustrate streaming characteristics of a streaming fluid inside a nozzle body in the region of the sac volume 11 for different sac volume contours wherein dark areas visualize regions of high or low mean flow velocity of a streaming fluid. Figure 4A shows streaming characteristics for a common nozzle body with a sac volume contour comprising a linear sac volume step which forms no cavity 10.
In contrast Figure 4B illustrates streaming characteristics for one embodiment of the described nozzle body 1 in accordance with Figure 2A to 2C and Figure 3. The corresponding sac volume contour 9 comprises a circular shape 12 and a linear shape 13 which realizes the cavity 10 with the protrusion 14. From this comparison it becomes obvious, that energy of the streaming fluid is transferred into the cavity 10 which beneficially affects the streaming conditions of the fluid in the region of the sac volume 11 and the flow hole 17. The cavity 10 represents a low velocity recirculation flow area which enables improved spray quality and reduced flow oscillations, in particular inside the flow hole 17.
Figures 5A and 5B show in a perspective view a further illustration of streaming conditions inside the region of the sac volume 11 by picturing flow lines for a common nozzle body (Figure 5A) and the nozzle body 1 as described above (Figure 5B). In analogy to the Figures 4A and 4B it is apparent from this comparison that the cavity 10 influences the streaming behavior of the streaming fluid and hence affects the spray quality and the penetration of the fluid spray.

Reference signs

1: nozzle body
3: nozzle wall
5: penetrating opening
7: needle seat
9: sac volume contour
10: cavity
11: sac volume
12: spherical shape of the sac volume contour
13: linear shape of the sac volume contour
14: protrusion
15: notch
17: flow hole
21: fluid inlet end
22: fluid outlet end
30: fluid injector
32: needle

D: distance of the cavity to the flow hole inlet
H1: height of a linear sac volume step
H2: height of a linear shape of the sac volume contour
L: longitudinal axis of the nozzle body
L1: length of a linear shape of the sac volume contour
L2: length of a further linear shape of the sac volume contour
R: radius of various spherical shapes of the sac volume contour

Claims

Nozzle body (1) for a fluid injector, comprising
- a nozzle wall (3) limiting a penetrating opening (5) of the nozzle body (1) along a longitudinal axis (L) from a fluid inlet end (21) to a fluid outlet end (22) of the nozzle body (1),

- a needle seat (7) formed as a portion of the nozzle wall (3) to interact with a needle (32) to prevent a fluid flow through a flow hole (17) in a closed position and otherwise to enable it, wherein the flow hole (17) penetrates the nozzle wall (3) in the region of the fluid outlet end (22) from the opening (5) to outside of the nozzle body (1), and

- a sac volume portion (9) of the nozzle wall (3) formed in the region of the fluid outlet end (22) such as to limit a sac volume (11), wherein the sac volume portion (9) limits a cavity (10) between the needle seat (7) and the flow hole (17) with respect to the longitudinal axis (L) to generate a stagnating flow area for a streaming fluid.
Nozzle body (1) in accordance with claim 1, wherein the sac volume portion (9) comprises a protrusion (14) in the region of the cavity (10).
Nozzle body (1) in accordance with claim 1 or 2, wherein the sac volume portion (9) comprises a section shaped to limit a ring shaped notch (15) forming the cavity (10).
Nozzle body (1) in accordance with claim 3, wherein with respect to a cross section along the longitudinal axis (L) the notch (15) comprises a linear shape (13) adjacent to a circular shape (12).
Nozzle body (1) in accordance with claims 2 or 3, wherein with respect to a direction from the fluid inlet end (21) to the fluid outlet end (22) and with respect to a cross section along the longitudinal axis (L) the notch (15) comprises
- a circular shape (12) having a predetermined radius (R) radially extending from the longitudinal axis (L).
Nozzle body (1) in accordance with one of the claims 1 to 4, wherein
with respect to a direction from the fluid inlet end (21) to the fluid outlet end (22) and with respect to a cross section along the longitudinal axis (L) the notch (15) comprises
- a circular shape (12) having a predetermined radius (R) radially extending from the longitudinal axis (L), and

- a linear shape (13) having a predetermined length (L2) extending parallel to the longitudinal axis (L).
Nozzle body (1) in accordance with one of the claims 1 to 4, wherein
with respect to a direction from the fluid inlet end (21) to the fluid outlet end (22) and with respect to a cross section along the longitudinal axis (L) the notch (15) comprises
- a linear shape (13) having a predetermined height (H2) extending parallel to the longitudinal axis (L).

- a linear shape (13) having a predetermined length (L1) extending perpendicular to the longitudinal axis (L),

- a circular shape (12) having a predetermined radius (R) radially extending from the longitudinal axis (L), and

- a linear shape (13) having a predetermined length (L2) extending parallel to the longitudinal axis (L).
Fluid injector (30), comprising
- a nozzle body (1) in accordance with one of the claims 1 to 7, and

- a needle (32) which is arranged axially movable in the opening (5) of the nozzle body (1) with respect to the longitudinal axis (L) to prevent a fluid flow through the flow hole (17) in a closed position and otherwise to enable it.