DE102014211287A1 - Fluid injection device for an internal combustion engine - Google Patents

Abstract

Fluid injection device (1) for an internal combustion engine, wherein the fluid injection device (1) comprises a valve body (2), wherein within the valve body (2) at least one valve needle (3) and at least one control chamber (4) are arranged, wherein the Control chamber (4) via a supply throttle (5), a fluid can be supplied and via a first outlet throttle (6) from the control chamber (4) can be discharged, via a pressure change of the fluid within the control chamber (4), the position of the valve needle (3 ), wherein the pressure change via the inlet throttle (5) and / or the first outlet throttle (6) can be controlled, wherein the fluid injection device (1) comprises at least a second outlet throttle (7), so in addition via the second outlet throttle (7) the fluid can be removed from the control chamber (4).

Description

Field of the invention

The present invention describes a fluid injection device for an internal combustion engine.

State of the art

Through injection devices of any kind, heat engines are supplied with the required fuel for internal combustion. The fuel is brought from a pump to system pressure and fed to the injector. The injector generally includes a nozzle body and a nozzle needle, wherein the control of the nozzle needle movement (opening or closing) via the pressure drop triggered by a pressure valve and / or pressure increase within a control chamber through which the fuel is passed, takes place. The pressure drop and / or pressure rise in a control chamber is usually regulated via two throttles, the fuel outlet throttle and the fuel inlet throttle, with different cross sections. The ratio of the defined by the cross sections of the two throttles fuel flow, sequence to inlet (A / Z), is a specific factor for the opening speed of the nozzle needle. The inlet regulates the closing speed of the nozzle needle. Due to ever-increasing system pressures (up to 3000 bar), the inlet throttle and outlet throttle are selected such that the injector functions from the minimum pressure (250 bar) up to the maximum pressure. In particular, the slow opening of the nozzle needle at low system pressures and the effects of rapid opening of the nozzle needle at high system pressures is a problem.

At high system pressures also results in the sealing seat of the pressure valve, the problem that during the expansion of the fuel from the maximum system pressure to ambient pressure special measures on the sealing seat of the pressure valve for cavitation erosion prevention are necessary.

The DE 102 46 974 A1 describes a fuel injection device comprising a housing and two coaxially arranged valve needles each associated with a control chamber, wherein the control chambers are arranged coaxially and at the same height. In the fuel injection device described, the pressure in the control chambers via one inlet throttle and one outlet throttle is regulated. By assigning one control chamber each to a valve needle, a precise switching over the existing fuel pressure within the control chamber is made possible. Due to the coaxial arrangement of the control rooms in the same height and a compact design can be displayed.

The fuel-to-fuel flow ratio (A / Z ratio) is determined by throttle cross-section selection and can not be arbitrarily adjusted during operation (increase or decrease in fuel flow through the drain throttle).

Summary of the invention

It is an object of the invention to provide an improved variant of a fluid injection device of the type mentioned, wherein a controllable injection at high system pressure and a sufficiently large injection amount at low system pressure is made possible.

The object is achieved by a fluid injection device for an internal combustion engine, wherein the fluid injection device comprises a valve body, wherein within the valve body at least one valve needle and at least one control chamber are arranged, wherein the control chamber via a supply throttle, a fluid can be supplied and a first outlet throttle can be removed from the control chamber, wherein the position of the valve needle can be controlled via a pressure change of the fluid within the control chamber, wherein the pressure change via the inlet throttle and / or the first outlet throttle can be controlled, wherein the fluid injection device at least a second Outflow throttle includes, so that additionally via the second outlet throttle, the fluid can be removed from the control room.

The fluid injection device according to the invention thus comprises a control chamber via which the position of the valve needle (lifting movement, opening or closing) is controlled. At the control room a second outlet throttle is provided, through which the outlet throttle cross-section is increased. By increasing the throttle cross-section of the outlet throttle, a large pressure drop is generated in the control chamber and thus the valve needle is opened faster and more reliably at low system pressures.

Further developments of the invention are specified in the dependent claims, the description and the accompanying drawings.

The first outlet throttle and / or the second outlet throttle are preferably switchable, that is openable and closable. In particular, the second outlet throttle is switchable independently of the first outlet throttle.

Due to the possibility of controlled opening and / or closing of the first and / or the second drain throttle, the drain to inlet ratio during operation of the internal combustion engine can be controlled.

The throttle cross sections are preferably to be selected such that the throttle cross section of the second outlet throttle is at least equal to, preferably larger, than the throttle cross section of the first outlet throttle.

The second outlet throttle from the control chamber is preferably arranged parallel to the first outlet throttle. In a parallel arrangement of the first and second outlet throttle is released by control either the throttle cross section of the first outlet throttle, the throttle cross section of the second outlet throttle or the throttle cross section of both outlet throttles.

According to the invention, only the first outlet throttle is used at high system pressures, d. H. kept the second outlet throttle closed, thereby preventing too rapid opening of the valve needle.

By contrast, at low system pressures, the first outlet throttle and the second outlet throttle are used, or with a sufficiently large throttle cross section of the second outlet throttle, the second outlet throttle. As a result, the outlet throttle cross-section is increased and a sufficiently fast opening at low system pressures achieved.

The control of the valve needle movement (opening or closing) takes place via the pressure drop triggered by a pressure valve and / or pressure rise within a control chamber through which fluid is passed. The pressure valve is formed by a valve ball on a valve ball seat (ball-cone seat valve).

The pressure valve can also be designed as a flat seat valve (180 ° seat angle) and / or as a conical seat valve.

By a serial arrangement of the parallel arranged first and second outlet throttle with a third outlet throttle, which is connected upstream of the pressure valve, a multi-stage pressure reduction within the fluid injection device is achieved when opening the pressure valve (the valve ball is lifted from the valve ball seat). As a result, the Kavitationseriosions inclination is significantly reduced and thus increases the life of the fluid injection device.

If the first outlet throttle and the second outlet throttle are formed in a switching valve, then the switching valve is biased by a return spring at low system pressures against a first sealing edge - both the first outlet throttle, as well as the second outlet throttle can be traversed by fluid.

At high system pressures, the switching valve seals against a second sealing edge, wherein the second outlet throttle is closed and only the first outlet throttle is traversed by fluid.

Brief description of the drawings

The invention will now be described by way of example with reference to the drawings.

1 Sectional view of a fluid injection device according to the invention with a pressure valve in two switching positions

2 Sectional view of a fluid injection device according to the invention with two pressure valves

3 Diagram "Injection quantity vs. Electrical drive time "

Detailed description of the invention

1 shows a simplified sectional view of the fluid injection device according to the invention 1 with a pressure valve comprising a valve ball 12 on a valve ball seat 14 , And a pressure relief valve upstream third outlet throttle 10 , Excess fluid in the fluid injection device relaxes via the pressure valve 1 from a system pressure PS to an ambient pressure PU. The first outlet throttle 6 and the second outlet throttle 7 are parallel to each other in a switching valve 9 arranged. The third outlet throttle 10 is serial to the first outlet throttle 6 and / or second outlet throttle 7 arranged.

In 1 To the left of the center line ML of the fluid injection device, the switching position is shown at low system pressure P1. In this position, the control room 4 and drain control room 13 over the first outlet throttle 6 and the second outlet throttle 7 connected with each other. Outside the valve ball 12 prevails an ambient pressure PU and upstream of the inlet throttle 5 to the valve ball 12 a system pressure PS. Will the valve ball 12 from the valve ball seat 14 moved, so created over the entire chain of flow-through chokes - third outlet throttle 10 , second outlet throttle 7 , first outlet throttle 6 and inlet throttle 5 A two-stage pressure drop across the drain control room 13 and the control room 4 , The level of pressure drop defines a speed of movement of the valve needle 3 ,

Depending on the set spring force of the return spring 8th , Cross sections of the inlet throttle 5 , of the first outlet throttle 6 , the second outlet throttle 7 and the third outlet throttle 10 creates a balance of power, which is the switching valve 9 holds up to a defined system pressure PS in the position shown to the left of the center line ML.

In 1 to the right of the centerline ML of the fluid injector 1 is the switching position at high system pressure P2 shown. As the system pressure PS increases, so do the pressures in the control room 4 and in the flow control room 13 , From a defined system pressure PS becomes the switching valve due to the changing balance of forces 9 after opening the valve ball 12 pushed up (position to the right of the center line). From this point on, the second outlet throttle is 7 without fluid flow, as the switching valve 9 at a second sealing edge 15 seated and the flow of fluid through the second outlet throttle 7 blocked. This in turn results in changed pressures within the control room 4 and the sequence control room 13 and subsequently a changed movement speed of the valve needle 3 ,

2 shows a simplified sectional view of the fluid injection device according to the invention 1 with parallel arrangement of the first outlet throttle 6 and the second outlet throttle 7 and two pressure valves, each having a valve ball 12 and a valve ball seat 14 include. The control room pressure in the control room 4 and thus the speed of movement of the valve needle 3 This is again about influencing the ratio of the first outlet throttle 6 and second outlet throttle 7 controlled to inlet throttle. Depending on the system pressure PS, the first outlet throttle 6 , the second outlet throttle 7 or first outlet throttle 6 and second outlet throttle 7 to be flowed through at the same time.

3 shows the influence of a changed sequence to inlet ratio at low system pressures P1 and P2 high system pressures on the injection quantity Y as a function of the electrical control period X. The continuous line describes a small drain to inlet ratio - that is, the drain throttle has a small cross section on. The dashed line shows the behavior at a high drain to inlet ratio - that is, an enlarged cross section of the drain throttle. Particularly striking is the difference in the injection quantity Y at low system pressures P1.

LIST OF REFERENCE NUMBERS

1

Fluid injection apparatus

2

valve body

3

valve needle

4

control room

5

inlet throttle

6

First outlet throttle (high system pressure)

7

Second outlet throttle (low system pressure)

8th

Return spring

9

switching valve

10

Third outlet throttle

11

First sealing edge

12

valve ball

13

Flow-control chamber

14

Valve ball seat

15

Second sealing edge

ML

center line

PU

ambient pressure

PS

system pressure

P1

low system pressure

P2

high system pressure

Y

Injection quantity

X

Electric control period

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10246974 A1 [0004]

Claims (11)

Fluid injection device ( 1 ) for an internal combustion engine, wherein the fluid injection device ( 1 ) a valve body ( 2 ), wherein within the valve body ( 2 ) at least one valve needle ( 3 ) and at least one control room ( 4 ) are arranged, wherein the control room ( 4 ) via an inlet throttle ( 5 ) a fluid can be supplied and via a first outlet throttle ( 6 ) from the control room ( 4 ) can be removed, wherein a pressure change of the fluid within the control room ( 4 ) the position of the valve needle ( 3 ), whereby the pressure change via the inlet throttle ( 5 ) and / or the first outlet throttle ( 6 ), characterized in that the fluid injection device ( 1 ) at least one second outlet throttle ( 7 ), so that in addition via the second outlet throttle ( 7 ) the fluid from the control room ( 4 ) can be dissipated. Fluid injection device ( 1 ) for an internal combustion engine according to claim 1, characterized in that the first outlet throttle ( 6 ) and / or the second outlet throttle ( 7 ) are switchable. Fluid injection device ( 1 ) for an internal combustion engine according to claim 1 or 2, characterized in that the first outlet throttle ( 6 ) and / or the second outlet throttle ( 7 ) are independently switchable. Fluid injection device ( 1 ) for an internal combustion engine according to one of claims 1 to 3, characterized in that the second outlet throttle ( 7 ) parallel to the first outlet throttle ( 6 ) is arranged. Fluid injection device ( 1 ) for an internal combustion engine according to one of the preceding claims, characterized in that the throttle cross section of the second outlet throttle ( 7 ) is at least the same size, preferably larger than the throttle cross section of the first outlet throttle ( 6 ). Fluid injection device ( 1 ) for an internal combustion engine according to any one of the preceding claims, characterized in that the fluid injection device ( 1 ) is designed so that at low system pressure (PS) in the control room ( 4 ) the first outlet throttle ( 6 ) and the second outlet throttle ( 7 ) are open and at high system pressure (PS) in the control room ( 4 ) the first outlet throttle ( 6 ) is open and the second outlet throttle ( 7 ) closed is. Fluid injection device ( 1 ) for an internal combustion engine according to one of the preceding claims, characterized in that the first outlet throttle ( 6 ) and the second outlet throttle ( 7 ) serially to a third outlet throttle ( 10 ) are arranged. Fluid injection device ( 1 ) for an internal combustion engine according to any one of the preceding claims, characterized in that in the fluid injection device ( 1 ) at least one pressure valve ( 16 ), wherein the pressure valve is a valve ball ( 12 ) and a valve ball seat ( 14 ). Fluid injection device ( 1 ) for an internal combustion engine according to one of the preceding claims, characterized in that the first outlet throttle ( 6 ) and the second outlet throttle ( 7 ) in a switching valve ( 9 ) are formed. Fluid injection device ( 1 ) for an internal combustion engine according to claim 9, characterized in that the switching valve ( 9 ) via a return spring ( 8th ) at low system pressure (PS) against a first sealing edge ( 11 ) is biased. Fluid injection device ( 1 ) for an internal combustion engine according to claim 9 or 10, characterized in that the switching valve ( 9 ) at high system pressure (PS) against a second sealing edge ( 15 ) seals, so that the second outlet throttle is closed at high system pressure.

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