WO2011117029A1

WO2011117029A1 - Common-rail injector having a pressure-balanced control valve and additional reservoir volume

Info

Publication number: WO2011117029A1
Application number: PCT/EP2011/052321
Authority: WO
Inventors: Stephan Amelang; Helene Kasjanow; Klemens Steinberg; Roman Etlender
Original assignee: Robert Bosch Gmbh
Priority date: 2010-03-24
Filing date: 2011-02-17
Publication date: 2011-09-29
Also published as: EP2550446A1; DE102010003202A1; CN102822496B; CN102822496A

Abstract

The invention relates to an injector, in particular a fuel injector for an internal combustion engine, comprising an actuator module 8 controlling a valve 15 for setting a through-flow of a fluid medium, wherein the valve 15 connects a control chamber 4 for control of a control piston to a low-pressure region. The invention provides an injector which is improved with regard to the functional requirements for being capable of multiple injections. This is achieved in that the control chamber 4 is interconnected with a reservoir volume. The reservoir volume is a reservoir space 16, which is arranged in a valve body 7 of the injector.

Description

description

Title:

Common rail injector with pressure-compensated switching valve and additional storage volume

The invention relates to an injector, in particular fuel injector for an internal combustion engine, comprising an actuator module dominantly a valve for adjusting a flow of a fluid medium, wherein the valve a

Control chamber for controlling a control piston with a low pressure area connects.

State of the art

Such an injector is known from DE 10 2007 044 356 A1. This injector for injecting fuel into a combustion chamber of an internal combustion engine has an adjustable between a closed position and the fuel flow releasing open position needle body which is actuated by means of a sleeve-shaped valve member having valve, and wherein the valve element cooperates with a arranged on a valve member valve seat. This injector has a pressure pin enclosed by the valve element and separate from the component, and the valve seat is designed as an outer cone. Finally, a space is arranged in a valve body of the injector, which is connected via a channel to the low-pressure region of the injector.

Disclosure of the invention The object of the invention is to provide an injector which is improved in terms of the functional requirements for multiple injection capability. This object is achieved in that the control room is connected to a storage volume. This embodiment is based on the following finding. At rest, the closing force is greater than the opening force generated by the fuel inventively embodied injectors. The closing force is varied by pressure variation in the control chamber, with high pressure prevailing in the control room when at rest. The control chamber is connected via an inlet channel with activated inlet throttle with the high-pressure region of the fuel system, while the control chamber is connected via a flow channel with activated outlet throttle controlled via the valve with the low pressure region of the fuel system. By actuating the actuator module and thus opening the valve, the pressure in the control chamber is lowered and the pressure in the control chamber is lowered

Control piston, which is designed in particular as a needle body moves from a valve seat in a valve body tip of the injector. When the valve is closed, the drainage channel is closed, and the needle body is moved back onto the valve seat by fuel flowing in via the inlet channel. The injection is complete. It has now been observed that during the opening and closing operations of the injection channels and due to the pressure differences in the control chamber, pressure waves are triggered which directly influence the injection quantity accuracy and the multiple injection capability. With very short intervals between two injections, very large volume waves are produced in the previous injectors. By mounting a storage volume as a so-called "minirail" on the injector, whereby the storage volume is under high fuel pressure, these pressure oscillations are dampened, with the result that the quantity waves between two injections are significantly reduced and the injection accuracy is increased. However, it has proved to be advantageous if, as provided in a further development of the invention, the storage volume is a storage space interconnected with the control space, which in turn in a further embodiment at least largely in a valve body of the In this case, all properties associated with a particular injector can be taken into account with regard to the design and the size of the storage volume. It is again provided in a further embodiment, that the storage space then extends to the control chamber along the valve body surrounding the needle body. Thus, the memory space can be integrated without costly change of an injector in this.

In a further development of the invention, the storage volume is greater than 1500 mm ³ , in particular greater than 2000 mm ³ . In this case, the precise design depends on the size and design of the respective injector, wherein the tuning takes place in such a way that the quantity wave amplitudes experience maximum damping.

In a further embodiment of the invention, the injector has a partial length L1 extending in the valve body from the control chamber to a paragraph comprising a first substantial portion of the storage volume and a partial length L2 extending from the paragraph to a valve seat, wherein the ratio L1 to L2 is in the range of 1 to 1 to 1 to 3. This aspect ratio is in turn dependent on the design and the size of the respective injector and is to be chosen so that the shaft travel times are set specifically and tuned to the natural frequency of the needle body. Again, in a further embodiment, the partial length L2 between 55 mm and 120 mm depending on the configuration and in particular the length of the respective injector. In contrast to the configuration at the part length L1, the storage volume extends with its second portion over the entire part length L2 and indeed with a diameter D2 via a subsequent needle body spring chamber up to a valve seat.

In a further embodiment of the invention, the hydraulic flow area unthrottled from the shoulder to the sealing end portion, which in turn is achieved in a further embodiment in that the hydraulic flow area is greater than 2 mm ² , in particular greater than 4 mm ² .

Further advantageous embodiments of the invention are described in the drawings, in which an embodiment of the invention is described in detail.

Brief description of the drawings Show it:

1 shows a longitudinal section through the injector according to the invention,

Figure 2 shows a longitudinal section through a valve body of the injector with essential Maßdefinitionen and

Figure 3 in diagram form representable by the inventive design of the injector length amplitude fluctuations and pressure oscillations compared to a conventional injector.

Embodiment of the invention

FIG. 1 shows a fuel! Njektor, which is used in particular in common-rail injection systems for self-igniting internal combustion engines. In such a common rail injection system is controlled by a high pressure pump fuel up to a pressure of about 3000 bar via a metering device to a high-pressure accumulator (rail) and stored in the high-pressure accumulator. The fuel injector according to the invention is connected to the high-pressure accumulator via a high-pressure line, which is screwed to the connecting piece 1 of the fuel injector. In the connecting piece 1, a filter 2 is used, which is intended to keep possible impurities in the fuel from the fuel injector.

The supplied via the connecting piece 1 fuel is supplied via an inlet channel 3 with throttle inserted a control chamber 4, which is arranged end of a needle body 5 in a needle body guide 6. The needle body guide 6 is in turn arranged and fixed in a valve body 7, wherein the connecting piece 1 is screwed into the valve body 7. Furthermore, adjacent to the needle body guide 6 and the valve body 7, an actuator module 8 is arranged, whose function will be described below.

Opposite to the control chamber 4, a valve body tip 9 is attached to the valve body 7 by means of a union nut 10. The needle body 5 extends with a needle body tip 1 1 into the end region of the Valve body tip 9 and forms a valve seat 19, from which in the needle body tip 1 1 injection channels 12, through which in the open state of the needle body 5 fuel is injected into the combustion chambers of the internal combustion engine, are shut off by the below-described fuel supply.

For fuel supply to the injection ports 12 upstream valve seat 19, which is formed by the needle body tip 1 1 and the valve body tip 9, a storage space 16 in the valve body tip 9 surrounding the needle body 5 is connected. The needle body 5 is further pressed by a arranged in the needle body spring chamber 18 needle body spring 13 in the direction of the valve seat 19 and thus supports the of the in the control chamber 4 prevailing fuel pressure exerted pressure force on the needle body. 5

To bring the needle body 5 and the needle body tip 1 1 in the open position for injection of fuel through the injection channels 12, the fuel pressure in the control chamber 4 is reduced until the upcoming fuel pressure the needle body 5 against the force of the needle body spring 13 in the direction to the control room 4 presses.

In order to control the fuel pressure in the control chamber 4 in a targeted manner, the control chamber 4 is connected via a drain channel 14 with an activated throttle to a valve 15 actuated by the actuator module 8, the valve 15 being connected to a low-pressure region of the fuel system on the actuator module side. If the valve 15 is moved by the actuator module 8 in its open position, fuel flows from the control chamber 4 via the drain passage 14 through the valve 15 in the low pressure region of the fuel system and the pressure in the control chamber 4 is consequently reduced. In this case, the throttle in the inlet channel 3 and the outlet channel 14 are tuned so that more fuel can flow through the drain channel 14 as nachströmt through the inlet channel 3 into the control chamber 4.

During the opening and closing operations of the valve 15 and the injection channels 12 through the needle body pressure waves are triggered, the injection quantity accuracy and directly affect the multiple injection capability. These pressure waves propagate in the storage space 16 up to the valve seat 19 and the adjacent injection channels 12.

In order to reduce these pressure waves at least, the control chamber 4 is connected to the storage space 16, which is arranged in the valve body 7 and the needle body 5 surrounding. The storage space 16 extends with a large diameter and consequently large volume from the control chamber 4 to a first shoulder 17 in the valve body 7 and further with a smaller diameter via the needle body spring chamber 18 to the valve seat 19th

In FIG. 2, important dimensional definitions are shown on the valve body 7 shown without actuator module 8 and needle body 5 and the valve body tip 9 for the subject matter of the invention. The storage space 16 extends with a length L1 from the control chamber 4 to the paragraph 17 with a relatively large diameter D1 and correspondingly large volume. From the shoulder 17, the effective storage space 16 extends over a region having a reduced diameter D2 in the needle body spring chamber 18 to the valve seat 19 (see Figure 1). By contrast, the length L2 is determined by the shoulder 17 and the valve seat 19 in the valve body tip 9. By selecting the ratio L1 / L2, the shaft travel times can be set specifically and tuned to the natural frequency of the needle body tip 11. The diameter D2 is to be dimensioned so that an effective hydraulic flow area is given so that no throttling occurs between the needle body 5 and the valve body 7.

FIG. 3 shows a schematic diagram with the injection quantity Q over the time t. The achieved and adjusted by the inventive design pressure swing curve is represented by a continuous graph, while the conventional pressure swing curve is represented by the graph shown in dashed lines. It can be seen that the vibration amplitudes are significantly reduced by the embodiment according to the invention.

Claims

claims

1 . Injector, in particular fuel injector for an internal combustion engine, comprising an actuator module (8) dominating a valve (15) for adjusting a flow of a fluid medium, wherein the valve (15) connects a control chamber (4) for controlling a control piston with a low pressure region, characterized in that the control chamber (4) is connected to a storage volume.

2. Injector according to claim 1,

characterized in that the storage volume is a storage space (16).

3. Injector according to claim 2,

characterized in that the storage space (16) is arranged in a valve body (7) of the injector.

4. Injector according to claim 2 or 3,

characterized in that the storage space (16) subsequently to the control chamber (4) along the valve body (7) surrounding the designed as a needle body (5) control piston extends.

5. Injector according to one of the preceding claims,

characterized in that the storage volume is greater than 1500 mm ³ , in particular greater than 2000 mm ³ .

6. Injector according to one of claims 3 to 5,

characterized in that the injector has a partial length L1 extending in the valve body (7) from the control chamber (4) to a shoulder (17) comprising a first portion of the storage space (16) and a partial length L2 extending from the shoulder (17) ) to a valve seat (19), wherein the ratio L1 to L2 is in the range of 1 to 1 to 1 to 3.

7. Injector according to claim 6,

characterized in that the partial length L2 is between 55 mm and 120 mm.

8. Injector according to one of the preceding claims,

characterized in that the hydraulic flow area D2 is unthrottled from the shoulder (17) to the valve seat (19).

9. Injector according to claim 8,

characterized in that the hydraulic flow area D2 is greater than 2 mm ² , in particular greater than 4 mm ² .