CN110234865B

CN110234865B - High-pressure accumulator for a high-pressure fuel injection system

Info

Publication number: CN110234865B
Application number: CN201880007704.8A
Authority: CN
Inventors: P·阿利奥
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2017-01-19
Filing date: 2018-01-15
Publication date: 2022-05-24
Anticipated expiration: 2038-01-15
Also published as: KR20190103390A; JP6855582B2; JP2020505548A; WO2018134144A1; EP3571387B1; FR3061934B1; EP3571387A1; FR3061934A1; CN110234865A

Abstract

The invention relates to a high-pressure accumulator for a high-pressure injection system, comprising a cylinder (11) which delimits a high-pressure chamber (12,12a) and a connecting piece (13,13a) which is provided with an outlet channel (131,131a) into the chamber (12,12a) and is provided with a throttle in each case in order to attenuate pressure waves generated by an injector connected downstream. The connecting pieces (13,13a) each have a channel (131,131a) at the outlet, which has a chamber (1312,1312a) that receives an insert (2,2a) provided with a throttle (22,22 a). The insert (2,2a) is fixed in the chamber (1312,1312a) in a force-fitting manner by a self-tightening process of the high-pressure accumulator.

Description

High-pressure accumulator for a high-pressure fuel injection system

Technical Field

The invention relates to a high-pressure accumulator for a high-pressure injection system, comprising a cylindrical body delimiting a high-pressure chamber, and a connecting piece which is provided with an outlet channel for high-pressure fluid into the chamber and is provided with a throttle in order to attenuate pressure waves generated by injectors connected downstream.

Background

A high-pressure accumulator of such a high-pressure injection system is known, which is shown in fig. 7. The rail 100, also referred to as a "high-pressure accumulator", is formed by a cylindrical body 111 made of thick forged steel, which surrounds a high-pressure chamber 112. The body of the rail has outlet connections 113 for connecting high-pressure lines, which are each connected to one injector. The connection 113 is penetrated by a hole 114 leading into the chamber 112. There is a bored restriction 115 at the base of the bore at the connection to the chamber. The throttle 115 damps pressure waves which are generated in the high-pressure fluid of the rail as a result of the closing movement of the injectors associated with each connection. The restriction 115 created by the orifice is sometimes referred to as a "nozzle".

Although this solution is capable of attenuating pressure waves, it has a certain number of drawbacks, in particular it is less effective, since the orifice constituting the restriction cannot be made with established geometry.

This solution also does not comply with strict tolerances. Furthermore, this embodiment produces edges in the form of holes in the plane of the opening of the channel into the chamber, which produce a strong dispersion in the wave attenuation. In order to avoid this, it is necessary to electrochemically treat the edges of the aperture opening in order to round them and to remove possible burrs or parts protruding into the chamber, which is a difficult and therefore expensive process.

According to the prior art, there are also alternatives to nozzles in the shape of insertion nozzles drilled into the rail. Such nozzles are inserted in the conventional manner by controlling the geometrical clearance of the die (form-locking clamping) and using a press fit, wherein the insertion force is controlled. The inserted nozzle is used only for rails without or with little self-reinforcement, since self-reinforcement causes residual deformations which jeopardize the control of the form-locking clamping. In this case, an expensive additional post-treatment process for the insertion diameter is required after the self-strengthening. This known solution therefore has a number of drawbacks.

Disclosure of Invention

The object of the present invention is to develop a high-pressure accumulator for a high-pressure injection system, which can effectively damp pressure waves in the rail that are generated as a result of the closing of the injection valves of the injectors connected downstream, and at the same time can be produced simply and produces a weak dispersion of damping between the nozzles of the same rail or of different rails.

For this purpose, the invention relates to a high-pressure accumulator for a high-pressure injection system of an internal combustion engine, which high-pressure accumulator is formed by a cylindrical body which delimits a high-pressure chamber and a connecting piece. One or more of the connections are provided with one or more outlet passages for high pressure fluid to the chamber. A throttle is arranged in the outlet channel in order to attenuate pressure waves of the downstream connected injector. The connecting pieces each have a passage at the outlet, which passage has a chamber that receives an insert provided with a throttle. The insert is arranged in the chamber in a force-fitting manner by means of a self-reinforcing process (Autofreezing-Prozess) of the high-pressure accumulator.

The high-voltage accumulator according to the invention can be produced in a simple manner and also has a throttle with small tolerances. The fixed connection of the insert in the high-voltage accumulator is achieved in a simple manner and without the need for new or other components, since it is achieved by the self-reinforcing of the rail. Self-reinforcing of rails is a known manufacturing process in order to ensure fatigue properties of the rails. This does not extend the production cycle.

The throttle formed outside the rail can be produced simply by a drilling process and a finishing process outside the rail, without the risk of foreign bodies being introduced into the rail and without any burr problems being avoided in the rail, which, on the contrary, makes it possible to produce smooth edges or rounding.

The passage of the insert therefore has a rounding at the opening on the side of the high-pressure chamber.

According to another advantageous feature, the passage in the insert is a stepped hole constituted by a series of holes of progressively decreasing diameter, separated by conical functional portions. A stepped restriction is thus created which enables a better optimization of the insert in terms of the damping/system efficiency loss compromise.

A series of holes with decreasing diameter is only an example of a complex geometry that can be achieved by nozzles machined separately from the rail. The aim is to obtain an asymmetry of the pressure loss, i.e. less pressure loss in the direction favorable for injection and more pressure loss in the direction only favorable for damping.

According to another feature, the passage with throttling has a conical inlet forming a sealing seat for the self-reinforcing process.

According to another feature, the connection piece here also has a tapered entrance in order to create a seal for self-reinforcement.

According to a still more particular feature, the chamber is cylindrical and forms with the hole a shoulder that creates the sealing edge. The insert has an outer surface with a cylindrical portion of large diameter to enter the cylindrical chamber with clearance when assembled. Furthermore, the insert has a portion of small diameter, which protrudes freely in the bore of the connecting piece, wherein the two portions of the insert are connected by a tapered section, which is defined for abutment onto an edge of the connecting piece.

According to another feature, the connection piece has a tapered chamber which continues through an aperture having a cross section smaller than that of the small base of the tapered chamber. And, the insert with the throttling portion has a cone with a length smaller than the length of the tapered chamber and a cross section of its small base larger than the cross section of the small base of the chamber, wherein the taper of the chamber and the taper of the cone are the same.

Advantageously, in the case of a conical chamber, the surface of the conical chamber and/or the surface of the cone has a non-uniform, uneven and raised or recessed geometry for improving the adhesion capability of the two faces to be contacted by self-reinforcement and also for better sealing when self-reinforcing.

According to another feature, the portion of the insert that enters the hole has a cross section that is smaller than the cross section of the hole so as not to come into contact with the hole after the rail and the insert are self-reinforcing.

In this way, the connection surface between the insert and the connecting element is reduced by a single contact surface, which can be tensioned by self-reinforcement.

According to another feature, the length of the portion of the insert is smaller than the length of the hole, so that the opening of the throttling is clearly distant from the opening of the hole into the chamber. The outlet of the bore of the insert is therefore significantly higher than the inlet of the bore in the chamber and affects the pressure loss.

If the high-pressure accumulator has a plurality of connecting pieces, an insert piece with a throttle according to one of the embodiments described above is preferably arranged in the connecting piece leading to the downstream connected injector.

The object of the invention is also to produce a high-voltage accumulator as defined above, wherein the method is characterized in that:

-making a chamber in the outlet channel of each connection piece by milling,

manufacturing an insert through which the restriction extends, wherein the outer diameter of the insert matches the diameter of the chamber,

-installing an insert in each chamber,

-producing the tightness of the insert and of the inlet of the connection, and

the rail assembled in this way is subjected to a self-reinforcing pressure in order to treat the inner surface of the rail and to arrange the insert in the cavity of the connecting piece in a force-fitting manner.

As already explained above, the method of manufacturing the rail is particularly simple and at the same time offers the following advantages: a precise and effective throttle for damping pressure waves (pressure shocks) can be produced.

Drawings

The invention is explained in detail below on the basis of embodiments shown in the drawings, in which:

figure 1 is an axial cross-sectional view of a part of a high-pressure accumulator of a high-pressure injection system,

figure 2 is an axial cross-sectional view of an insert with a throttle for the high-pressure accumulator of figure 1,

figure 3a schematic half-section view of an embodiment of the high-voltage reservoir of figure 1,

figure 4 is an axial section of another embodiment of a high-pressure accumulator of an injection system according to the invention,

figure 5 is an axial section through an insert with a throttle for the high-pressure accumulator of figure 4,

figure 6 illustrates a half-sectional view of an insert with a throttle fitted into the connection piece of the high-pressure accumulator of figure 4,

fig. 7 shows a cross-sectional view of a known rail or high-voltage accumulator.

Detailed Description

According to fig. 1, the invention relates to a rail or a high-pressure accumulator 1 of a high-pressure injection system in an internal combustion engine. The usual part of the rail is shown in axial section. Other components of the jetting apparatus are not shown.

The high-pressure accumulator 1 is a thick-walled cylindrical body 11 made of forged steel, which encloses a high-pressure chamber 12 supplied with high-pressure fuel by a high-pressure pump in order to distribute the high-pressure fuel to injection valves (injectors) controlled by a central control unit of the engine.

The closing and opening movements of the injectors generate compression and decompression waves ("pressure shocks") which are transmitted from the high-pressure fluid into the lines connecting the injectors with the rail 1 and, therefore, into the rail.

The cylindrical body 11 has connections 13 for connection, which are connected to the high-pressure chamber 12 via channels 131 and to the injectors of the high-pressure line via the high-pressure line, respectively. The connector has threads 132 on the outside to screw the joint of the high-pressure line.

The example of figure 1 is limited to showing a conventional part of the rail, which has two connecting pieces 13, one of which is empty and the other of which has an insert 2 with a throttle. The rail 1, as with the supplied injectors, also has a plurality of connections 13 and high-pressure fuel outlets. All of these connectors 13 preferably have the same structure and the following description is limited to one of these connectors.

The connecting piece 13 on the right in fig. 1 shows its passage 131 without an insert having a throttle 2; the connection piece 13 on the left is provided with an insert with a throttle 2.

The insert with the throttle 2 is shown in fig. 2 in isolation in cross section.

According to fig. 1, the channel 131 is formed in the connection piece 13 in an orientation extending to the high-pressure chamber 12 by an inlet cone 1311, which is followed by a cylindrical chamber/bore 1312 having a larger diameter than the diameter of the bore 1314 located downstream, in order to form a sealing edge 1313. The channel 131 receives an insert with a restriction 2.

According to fig. 2, the insert with the throttle 2 has a cylindrical body 21 crossed by a stepped hole 22 constituted by a series of holes with gradually decreasing diameters 222,224,226, separated by conical connections 223, 225. The inlet of the insert 2 has a conical shape 221 forming a sealing seat and the opening to the last bore 226 in the chamber of the rail has a rounded edge or rounding 227.

The stepped bore 22 forms a throttle section determined for attenuating pressure waves (compression and decompression) which are introduced into the high-pressure fluid by the closing and opening movements of the injector.

The body 21 of the insert 2 with its outer surface 23 has a portion 231 with a large cross section which is joined to a portion 233 with a small cross section by a conical connection 232 which forms a bearing surface for co-action with an edge 1313 of the channel 131 of the connecting piece. The outer surface 23 of the portion 233 with a small cross-section ends at a rounded portion 234. The major diameter of the portion 231 of the insert 2 is slightly smaller than the diameter of the hole 1312 of the connecting element 13. The small diameter of the portion 233 is significantly smaller than the diameter of the hole 1314 of the connecting piece 13 downstream of the hole 1312, so that the insert 2 provided with a throttle can be mounted without difficulty in the channel 131 of the connecting piece 13 for assembly and the portion 233 with a small cross section does not come into contact with the wall of the channel 131 and in particular the hole 1314 of the connecting piece. The stepped bore 1312/1314 enables the diameter of the bore to be reduced in the plane where the stepped bore intersects the high pressure chamber 12, although it is not necessary for hydraulic function. The length of the portion 233 of the insert 2 is less than the length of the bore 1314 so that the opening of the restriction 226 is significantly further from the bore 1314 to the opening 1315 in the chamber 12.

The above description in terms of the length of the portion of the insert and the length of the bore of the connecting piece can also be applied to the second embodiment, which is described below.

As explained below, the jamming of the insert 2 or the force-locking arrangement of the insert is achieved by self-reinforcement.

According to the half section of fig. 3, the rail 1 is self-reinforcing when provided with inserts all having a restriction 2. For this purpose, a closure, not shown, is applied on each connecting piece 13 against the conical seat 221 of the insert 2. The support portion is formed in this manner. The tensioning force F applied along the axis xx during self-reinforcement produces the tightness of the insert 2 (zone a) and, by contact between the tapered surface 232 of the insert 2 and the edge 1313 of the connection piece 13, the tightness between the insert 2 and the channel 131 in zone B.

In this way the hole 131 and the face of the insert 2 exposed to the self-increasing high pressure of the fluid introduced into the rail are delimited.

The exposed faces are the face of the chamber 12 and the face of the channel 131 of the connection piece 13 (in the direction of outflow of the high-pressure fuel) in front of the insert 2, including the inner face of the insert 2 and the outer face of the insert in front of the contact between the tapered shoulder 232 and the edge 1313 separating the

holes

1312 and 1314 of the connection piece 13. In other words, the face is not exposed to the self-energizing high pressure fluid relative to insert 2 and bore 1312, but is instead subjected to forces generated by the high pressure. Thus, the very high self-reinforcing pressure plasticizes the inner layer of said exposed faces of the rail 1 and of the insert 2, which deforms so as to be pressed against the hole 1312 of the connecting element 13. After the very high self-reinforcing pressure is applied, the connecting piece 13 is tightened towards each insert 2, which is thereby contracted.

Fig. 4 shows a further embodiment of a rail 1a according to the invention, which is also limited to the conventional part of a rail with two connecting pieces 13a, one of which is empty and the other of which has an insert with a throttle 2 a. All such connectors 13a preferably have the same structure, so that the description of the connector is limited to one of the connectors.

The insert with the throttle 2a is shown in isolation in cross section in fig. 5.

According to fig. 4 and the orientation extended toward high-pressure chamber 12a, channel 131a in connection piece 13a is formed by an inlet cone 1311a, followed by a conical chamber 1312a whose small base has a larger diameter than the diameter of hole 1314a located downstream, so as to form a land 1313 a. The tapered chamber 1312a constitutes a "morse taper" or equivalent taper type of insertion chamber. The channel 131a receives, by insertion, an insert having a throttling 2a, which insert has a complementary shape.

According to fig. 5, the insert with the throttling 2a has a body 21a crossed by a stepped hole 22a constituted by a series of holes with gradually decreasing

diameters

222a,224a,226a, separated by

conical connections

223a,225 a. The inlet 221a of the insert 2a has a conical shape which forms a sealing seat, and the opening of the last bore 226a into the cavity 12a of the rail 1a has a rounded edge or radius 227 a. The stepped bore 22a forms a throttle portion that is determined for attenuating a pressure wave introduced into the high-pressure fluid.

The outer surface 23a of the insert 2a has a conical portion 231a with a large diameter, the small base of which is joined by a conical connection 232a to a cylindrical portion 233a with a small diameter. The outer surface 23a terminates at a radius 234 a. The tapered portion 231a has a taper identical to that of the tapered chamber 1312a of the connector 13 and has a cross-section that can be received by insertion in the tapered chamber 1312a so that the corresponding faces abut directly.

The cylindrical portion 233a has a cross-section significantly smaller than that of the hole 1314a of the connecting member 13 a.

According to the half section of fig. 6, when the rail 1a is equipped with inserts all having a throttle 2a, the rail 1a is subject to self-reinforcement as explained for the first embodiment shown in fig. 1-3.

To this end, on each connecting piece 13a closure, not shown, is applied against the conical seat 221a of the insert 2a, so as to create a seal with respect to the outside of the hole 22a and between the conical surfaces of the

portions

1312a and 231 a.

Here, a tensioning force F is applied to a ball, not shown, which is supported and forms the compression region C. The force is transmitted to the conical contact area between the conical portion 231a of the insert 2a and the conical surface of the cavity 1312a of the connector 13 a.

In this way, the bore 131a and the face of the insert 2a exposed to the self-increasing high pressure of the fluid introduced into the rail are delimited.

The exposed faces are the face of the chamber 12a and the face of the channel 131a of the connector 13a (in the direction in which the high-pressure fuel flows out) in front of the insert 2a, including the inner face of the insert 2a and the outer face of the insert in front of the contact between the tapered face 231a of the insert and the face of the tapered chamber 1312 a. The cross section of the small base of the conical portion 231a is greater than that of the conical chamber 1312a, which engages on a conical surface 1313a, which constitutes a shoulder, so that the insert 2a can be clamped in combination with self-reinforcement by insertion without abutting against the shoulder 1313a, which could interfere with or limit the insertion.

It can be determined that: the tapered face of

portion

1312a or 231a may have flutes that enhance sealability during self-reinforcement and increase residual axial force between the two portions/faces.

The face in contact with insert 2a and bore 1312a is not exposed to the self-energizing high pressure fluid, but is subjected to the forces generated. The very high self-reinforcing pressure plasticizes the inner layer of said exposed faces of the rail 1a and of the insert 2a, which deforms so as to be pressed against the hole 1312a of the connecting element 13 a. After the very high self-reinforcing pressure is applied, the connecting piece 13a is tightened towards each insert 2a, which is thereby contracted.

The forged steel of rails 1,1a has a minimum hardness in the order of 300HB, which depends on the hardness of the pipe head and the characteristics that can be conformed to the desired result of the self-reinforcement.

The material of the

insert

2,2a has a hardness of between 300 and 450HV in order to have sufficient plasticization during self-reinforcement and at the same time to maintain sufficient residual elasticity in order to have sufficient residual pressure between the

insert

2,2a and the rail 1.

The method according to the invention for manufacturing the rails 1,1a consists in:

placing the

insert

2,2a in the connecting

piece

13,13a with play without having to exert large forces,

clamping the assembly produced in this way so as to have a pressure difference between the inner and outer diameter of the

insert

2,2a, and

-generating plastic deformation of the

insert

2,2a and the rail 1,1 a.

The plastic deformation ensures a residual contact between the insert with the

throttle

2,2a and the rail 1,1 a.

The material properties of the insert part with the throttle are selected to ensure a sufficient residual force that holds the

insert part

2,2a in position during operation of the high-pressure accumulator 1,1a of the injection system.

List of reference numerals for the most important elements, without suffix "a" unless special case "

1 Rail

11 main body

12 high pressure chamber

13 connecting piece

131 channels

1311 inlet cone

1312 cylindrical chamber

1312a conical chamber

1313 sealing edge

1314 hole

132 external screw thread

2 insert with throttle

21 column body

21a taper

22 step hole

221 entrance cone

222 have holes of large diameter

223 taper connection part

224 have holes of medium diameter

225 taper joint

226 have a small diameter bore

227 rounded off portion

23 outer surface of

231 has a large diameter cylindrical portion

231a have a large diameter tapered portion

232 taper connecting part

233 cylindrical portion with a small diameter

234 rounded portion

Claims

1. A method for manufacturing a high-pressure accumulator for a high-pressure injection system, which high-pressure accumulator is formed by a cylindrical body (11) of a rail (1) delimiting a high-pressure chamber (12,12a) and by a connecting piece (13,13a) which is provided with an outlet channel (131,131a) opening into the high-pressure chamber (12,12a), wherein a throttle is arranged in at least one outlet channel (131,131a) in order to attenuate pressure waves generated by an injector connected downstream of the connecting piece (13,13a), characterized in that,

-producing a chamber (1312,1312a) in the outlet channel (131,131a) of each connection piece (13,13a) by milling,

-manufacturing an insert (2,2a) through which the restriction extends, wherein the outer diameter of the insert matches the diameter of the chamber (1312,1312a),

-installing an insert (2,2a) in each chamber, wherein the insert (2,2a) is placed with clearance in the connecting piece (13,13a) without having to exert large forces,

-producing the tightness of the insert (2,2a) and of the inlet of said connection (13,13a), and

-subjecting the high-pressure accumulator (1, 1a) assembled in this way to a self-reinforcing pressure in order to treat the inner surface of the high-pressure accumulator and to arrange the insert (2,2a) in a force-fitting manner in the cavity (1312,1312a) of the connection (13,13a), wherein the faces of the rail (1) and of the insert (2,2a) are plasticized in such a way that a very high self-reinforcing pressure is applied to the inner layer of the exposed faces of the rail (1) and of the insert (2,2a) and the inner layer is deformed in such a way that the insert (2,2a) is pressed against the cavity (1312,1312a) of the connection (13,13a), wherein the cavity (1312,1312a) is at least elastically deformed and enlarged, wherein, after the very high self-reinforcing pressure has been applied, the cavity (1312,1312a) of the connector (13,13a) is tightened towards the insert (2,2a), which is thereby contracted.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the passage of the insert (2,2a) has a rounding (227, 227 a) at the opening on the side of the high-pressure chamber (12,12 a).

3. The method of claim 2, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the passage in the insert (2,2a) is a stepped bore (22,22a) made up of a series of bores (222, 222a,224, 224a,226, 226 a) of progressively decreasing diameter separated by tapered features (223, 223a,225, 225 a).

4. The method according to claim 2 or 3,

it is characterized in that the preparation method is characterized in that,

the passage with the throttling has a conical inlet (221, 221 a) forming a sealing seat.

5. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the connecting piece (13,13a) has a conical inlet (1311, 1311 a).

6. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

-the chamber (1312) is cylindrical and forms a shoulder (1313) with a hole (1314) located downstream of the chamber (1312), said shoulder producing a sealing edge,

-the insert (2) has an outer surface (23) with a cylindrical portion of large diameter, so as to enter with clearance into the cylindrical chamber (1312) when fitted, and a portion (233) of small diameter, which protrudes freely in the hole (1314) of the connector (13),

-wherein the two parts (231, 233) of the insert (2) are connected by a tapered section (232) determined for abutting against an edge (1313) of the connecting piece (13).

7. The method as set forth in claim 1, wherein,

it is characterized in that the preparation method is characterized in that,

-the connector (13 a) has a tapered chamber (1312 a) which continues through an aperture (1314 a) having a cross section smaller than that of the small base of the tapered chamber (1312 a), and

-the insert with restriction has a cone (231 a) with a length smaller than the length of the conical chamber (1312 a) and a cross section of the small base of the cone being larger than the cross section of the small base of the conical chamber (1312 a),

-wherein the taper of the tapered chamber (1312 a) and the taper of the taper (231 a) are the same.

8. The method of claim 7, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the surface of the conical chamber (1312 a) and/or the surface of the cone (231 a) have an uneven, uneven and raised or recessed geometry in order to improve the tightness in combination with the cone when self-reinforcing, which enables the extrusion pressure to be ensured.

9. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

it is characterized in that the preparation method is characterized in that,

the portion (233, 233 a) of the insert (2,2a) entering into the hole (1314, 1314 a) located downstream of the chamber (1312,1312a) has a cross section smaller than that of the hole so as not to come into contact with the hole after the rail (1, 1a) and the insert (2,2a) are self-reinforced.

10. The method according to claim 6 or 9,

it is characterized in that the preparation method is characterized in that,

the length of the portion (233, 233 a) of the insert (2,2a) in the bore (1314, 1314 a) downstream of the chamber (1312,1312a) is smaller than the length of the bore (1314, 1314 a), so that the opening of the throttle of the insert (2,2a) is significantly further away from the opening of the bore (1314, 1314 a) into the high-pressure chamber (12,12 a).