JP2002537516A - Metering unit for metering liquids or gases - Google Patents

Abstract

(57) [Summary] The present invention is a metering unit for metering a liquid or gas, comprising a nozzle body (4) and an open position in a guide hole (5) of the nozzle body (4). A nozzle needle (6) movably guided between a closed position and at least one metering opening (9) which opens into the guide hole (5) by the nozzle needle (6). The nozzle needle (6) rests on the seal seat (8) of the nozzle body (4) in the closed position. In the present invention, the nozzle unit (2) is provided, and the nozzle needle (6) of the nozzle unit (29) is opened inward and has a dead stroke (hT). Features. This nozzle unit (2) is preferably designed as an injector for the common rail injection system of an internal combustion engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a nozzle unit for metering a liquid or gas, comprising a nozzle body and a nozzle needle movably guided between an open and closed position in a guide hole of the nozzle body. Wherein the nozzle needle controls at least one metering opening, the nozzle needle being located in a sealing seat of a nozzle body in a closed state.

Further, the present invention relates to a metering valve for metering a liquid or a gas, which is provided with a nozzle unit and an actuator unit for operating the nozzle unit.

[0003] Nozzle units and metering valves of this type are known from different embodiments of the prior art. These known metering valves are designed, for example, as injection valves for fuel injection systems of internal combustion engines. Such a metering valve has a nozzle unit for metering fuel and an actuator unit for operating the nozzle unit. The nozzle unit has a nozzle body, and a guide hole is provided in the nozzle body along a longitudinal axis. A nozzle needle is movably guided in the guide hole between an open position and a closed position. At the lower end of the nozzle unit, a seal seat is formed on the nozzle body. Outside the seal seat, a plurality of metering openings are provided in the nozzle body. These metering openings extend radially outward from the guide holes. In the closed position of the nozzle unit, the nozzle needle rests on the seal seat and prevents fuel from flowing out of the nozzle unit via the metering opening. The actuation of the actuator unit creates a high pressure inside the nozzle unit, which causes a movement of the nozzle needle in the direction towards the open position.

In the course of the opening stroke, the nozzle needle is lifted outward from the seal seat and fuel can flow out of the nozzle unit via the metering opening.
In the course of the opening stroke, the flow rate of the fuel flowing out is reduced by the cross section open between the nozzle needle and the seal seat. If the nozzle unit is opened relatively large, the cross section between the nozzle needle and the seal seat is larger than the cross section between the metering openings. The flow rate is then reduced by the cross section of the metering opening.
That is, the above-described nozzle unit has a so-called seat valve.

[0005] Known nozzle units are open outward. The nozzle unit opened outward is also called an A nozzle (A-Duese), or a metering valve having a nozzle unit opened outward, or an A valve. The problem with this A nozzle or A valve is the outward opening direction of the nozzle needle.

[0006] Heretofore, Vario nozzles have been known from the prior art, which nozzles do not have a seat valve. In this known Vario nozzle, the nozzle needle is likewise mounted on a sealing seat in the closed position of the nozzle unit, sealing one or more metering openings. During the course of the opening stroke, the nozzle needle is pulled outward from the seal seat. These metering openings are only opened when the nozzle needle has overcome the dead stroke. If this dead stroke has been overcome, the cross section is first opened between the nozzle needle and the seal seat, and this cross section is larger than the cross section of the metering opening. In another course of the opening stroke, after the dead stroke has been overcome, the metering opening is opened and fuel can flow out of the nozzle unit via the metering opening. The flow rate of the fuel flowing out through this open nozzle unit is restricted by the cross section of the metering opening. That is, the Vario nozzle does not have a seat valve.

[0007] Vario nozzles known from the prior art are formed as A nozzles. These metering openings are provided in the nozzle needle and extend radially outward. Inside the dead stroke, the outer opening of the metering opening is located inside the guide hole and is closed by the inner wall of the nozzle body. At the open position of the nozzle unit, outside the dead stroke, the nozzle needle is carried out of the guide hole such that the metering opening comes out of the nozzle body and the opening is opened, and as a result, the fuel is transferred through the metering opening. It can be discharged from the nozzle unit. Due to the movable metering openings, the known vario nozzles cannot guarantee the same direction and shape of the fuel flow exiting the metering openings over the entire opening stroke. Since noise-generating conditions, exhaust-gas conditions and the consumption of the internal combustion engine are also influenced by the direction and shape of the fuel flow, the known vario nozzles produce undesirable noise generation, exhaust-gas generation rates and / or consumption rates of the internal combustion engine. obtain.

[0008] Finally, the known Vario nozzle has the following disadvantages. That is, after the actuation of the actuator unit, a high pressure is applied to the guide gap between the nozzle body and the nozzle needle in the region of the guide hole inside the dead stroke in order to operate the nozzle unit. This high pressure is applied in the region of the guide gap, in particular towards the outside, where the nozzle unit is located inside the dead stroke and the small amount of fuel from the guide gap, despite not wanting the fuel to flow out of the nozzle unit Extrusion can be produced. The amount of fuel flowing out of the guide gap can reach the combustion chamber of the internal combustion engine and cause noise and / or exhaust gas generation and / or deterioration of fuel consumption.

[0009] The object of the invention is therefore to improve a nozzle unit of the type described at the outset, such that the nozzle unit on the one hand does not have a seat valve, but on the other hand does not have the disadvantages mentioned above. To provide.

In order to solve this problem, according to the invention, starting from a nozzle unit of the type described at the outset, the nozzle needle is open inward and has a dead stroke. .

In the nozzle unit according to the present invention, the nozzle needle is mounted on the valve seat at the closed position of the nozzle unit, and is sealed by one or more metering openings. This or these metering openings preferably extend radially outwardly from the guide holes in the nozzle body to the outer peripheral surface of the nozzle body. Inside the dead stroke, the nozzle needle is located over the inner opening of the metering opening. The inner opening of the metering opening is closed by the outer wall of the nozzle needle. During the course of the opening stroke, the nozzle needle is raised inward by the seal seat. The metering opening is only opened when the nozzle needle has overcome the dead stroke. As soon as this is the case, the cross section has previously been opened between the nozzle needle and the seal seat, which cross section is larger than the cross section of the metering opening. The flow rate of the medium flowing out of the opened nozzle unit is restricted by the cross section of the metering opening. The nozzle unit according to the invention is formed as a so-called vario nozzle without a seat valve.

The nozzle unit according to the invention is therefore open inward. As a result, there is no space problem at the end face of the nozzle unit due to the nozzle needle projecting outward from the nozzle body during the course of the opening stroke. In addition, the metering openings formed in the nozzle body are regularly arranged and do not move with the nozzle needle during the opening stroke. In this way, the same direction and shape of the medium flow to be metered out of the metering opening can be guaranteed over the entire opening stroke. The direction and shape of this flow can be precisely defined and defined according to external requirements, for example, the desired noise-generating conditions and / or exhaust-gas conditions and / or the consumption conditions of the internal combustion engine.

The nozzle unit according to the invention advantageously combines, for the first time, the advantages of a Vario nozzle with the advantages of an inwardly opened I-nozzle.

According to an advantageous embodiment of the invention, the provided nozzle unit is designed as a fuel injection nozzle for a fuel injection system of an internal combustion engine. The nozzle unit is preferably designed as an injector for the common rail fuel injection system of the internal combustion engine. The advantages of the nozzle unit according to the invention, especially in the common rail fuel injection system, arise in particular with regard to support.

According to an advantageous embodiment of the invention, an inflow line is formed in the nozzle body,
The inflow line opens into an annular chamber, which is formed on the inner peripheral surface of the guide hole, wherein the annular chamber, at least in the closed position of the nozzle unit, has a lateral hole formed in the nozzle needle. It is connected. A longitudinal hole formed in the nozzle needle branches off from the lateral hole. This longitudinal hole opens into the pressure chamber at the tip of the nozzle needle. In order to meter a defined amount of liquid or gas using the nozzle according to the invention, within the nozzle unit, exactly inside the inlet line, the annular chamber, the transverse holes, the longitudinal holes and the pressure chambers. High pressure is configured. The high pressure formed in the pressure chamber acts on the surface of the tip of the nozzle needle inside the seal seat,
This causes the nozzle needle to move in the direction toward the open position. After overcoming the dead stroke, a predetermined amount of liquid or gas can flow out of the nozzle unit via the metering opening.

In an advantageous manner, the pressure chamber is upwardly in the closed position of the nozzle unit by the nozzle needle and downwardly by the nozzle body and in the area of the guide hole, the inner wall of the nozzle body, the guide hole and the nozzle needle. And the guide seat between them. In the open position of the nozzle unit, the pressure chamber opens into at least one metering opening outside the dead stroke. In this position, a defined amount of the medium to be metered can flow out of the nozzle unit via the metering opening.

The annular chamber is limited outside the dead stroke in the open position of the nozzle unit, preferably by the outer wall of the nozzle needle. The connection between the annular chamber and the transverse bore in the open position is therefore interrupted outside the dead stroke. In this position, the medium to be metered cannot also flow out of the inlet into the pressure chamber. In this manner, the volume of the medium to be metered which will flow out of the nozzle unit outside the dead stroke in the open position can be limited by the volume of the transverse holes, longitudinal holes and pressure chambers.

According to an advantageous refinement of the invention, an annular leakage chamber is formed on the inner peripheral surface of the guide hole between the annular chamber and the pressure chamber, from which the leakage line branches. I have. High pressure is applied inside the dead stroke only in the region of the guide gap between the annular chamber and the leak chamber. Significantly lower leakage pressures occur in the remaining area of the guide gap, especially at the ends of the guide gap. With this improvement, it is possible to prevent a small amount of the medium to be metered from being pushed out of the guide gap inside the dead stroke at the end of the nozzle unit.

A plurality of first metering openings are formed in the nozzle body, and a plurality of second metering openings are formed above the first metering openings, wherein the first metering openings are the first metering openings. It has a cross section smaller than the double metering aperture. The metering opening preferably has a circular cross section.
In the course of the opening stroke, the first and second metering openings are sequentially opened, so that the medium to be metered first flows out of the first metering opening and then through the first and second metering openings. Can be. When the nozzle unit is used as an injection nozzle for a fuel injection system of an internal combustion engine, the fuel amount flowing out of the first metering opening is used for pre-injection, and the fuel flowing out of the second metering opening is slightly delayed. The quantity can be used for the main injection.

The greater variability for metering the medium to be metered is that the nozzle body is provided with a plurality of metering openings having a longitudinal cross section, the longitudinal axis of the cross section being the longitudinal axis of the nozzle unit. This can be achieved by extending parallel to the direction axis. The effective cross-sectional dimension of the metering opening is defined by the opening stroke of the nozzle needle outside the dead stroke at the opening position of the nozzle unit.

Another object of the present invention is to improve a metering valve for metering a liquid or gas of the type provided with a nozzle unit and an actuator unit for operating the nozzle unit, It is an object of the present invention to provide a metering valve having a unit, the nozzle unit having, on the one hand, no seat valve and, on the other hand, not having the disadvantages mentioned above.

In order to solve this problem, the present invention starts from a metering valve for metering a liquid or gas of a type in which a nozzle unit and an actuator unit for operating the nozzle unit are provided. The nozzle unit is formed as a nozzle unit having the configuration according to any one of claims 1 to 11.

Advantageously, the inflow line opens into the valve control chamber via the inflow restriction and the outflow line branches off from the valve control chamber via the outflow restriction and the control valve. In the closed position of the nozzle unit, the control valve is open. Via the inflow line, the medium to be metered is pumped by a pump device to the nozzle unit. When the control valve is open, the medium fed under pressure can flow from the inflow line to the outflow line via the inflow restriction, the valve control chamber, and the outflow restriction. The nozzle unit of the metering valve according to the invention is operated by actuation of an actuator unit. The actuation of the actuator unit closes the control valve in the outlet line. The medium to be metered further flows into the nozzle unit via the inflow line. When the control valve is closed in the closed position of the nozzle unit, the medium to be metered cannot flow out of the nozzle unit, so that the valve control chamber, the inlet, the annular chamber, the transverse holes, the longitudinal holes, and the pressure chambers Now the pressure is configured.

Depending on the pressure configuration, different forces act on the nozzle needle. On the one hand, the nozzle needle is pressed into the closed position by the spring force of the nozzle spring. On the other hand, the rear end of the nozzle needle opens into the valve control chamber. The pressure constituted by the valve control chamber acts on the end face of the nozzle needle which has entered the valve control chamber and generates a control force. This control force pushes the nozzle needle into the closed position. The pressure finally formed in the pressure chamber acts on the surface of the tip of the nozzle needle to generate an operating force. This operating force pushes the nozzle needle to the open position.

As soon as the operating force exceeds the combined force of the spring force and the control force based on the pressure increase, the nozzle needle is moved toward the open position. The metering opening is open outside the dead stroke and the medium to be metered can be discharged from the nozzle unit via the metering opening or the actuator unit is actuated again, the control valve is opened and the metering The pressure can be reduced if the desired medium can be flowed through the outlet throttle into the outlet line.

Next, advantageous embodiments of the present invention will be described in detail with reference to examples shown in the drawings.

In FIG. 1, the entire metering valve according to the invention according to the preferred embodiment is designated by the reference numeral 1. This metering valve 1 serves for metering a liquid or gas. The metering valve 1 has a nozzle unit 2 and an actuator unit 3 for operating the nozzle unit 2. The actuator unit 3 is formed, for example, as an electromagnet or piezoelectric actuator. The metering valve 1 is formed as an injector for a common rail fuel injection system of an internal combustion engine. The metering valve 1 is fixed to the internal combustion engine using a tightening nut 10 so that the tip of the nozzle unit 2 protrudes into the combustion chamber of the internal combustion engine.

The nozzle unit 2 has a nozzle body 4 and a nozzle needle 6 movably guided in a guide hole 5 of the nozzle body 4 between an open position and a closed position. At the tip of the nozzle unit 2, two metering openings 9 open in the guide holes 5. The nozzle needle 6 controls these two metering openings 9. In the closed position, the nozzle needle 6 is in contact with the seal seat 8 of the nozzle body 4 to prevent fuel from flowing out of the nozzle unit 2 through the metering opening 9. In FIG. 1, this nozzle unit 2
Is shown in the closed position. In the open position, the nozzle needle 6 is pulled up from the seal seat 8, and after the dead stroke (hr) is overcome, fuel can flow out from the metering opening 9.

An inflow pipe 11 is formed in the nozzle body 4, and the inflow pipe 11 is formed in the annular chamber 1.
It is open to 2. This annular chamber 12 is formed on the inner peripheral surface of the guide hole 5. The annular chamber 12 is configured to be connected to a lateral hole 13 formed in the nozzle needle 6 when the nozzle needle 6 is in the closed position. From this lateral hole 13,
Similarly, a longitudinal hole 14 formed in the nozzle needle 6 is branched, and the longitudinal hole 14 opens to the pressure chamber 15 at the tip of the nozzle needle 6. Furthermore, the inflow line 11 opens into the valve control chamber 17 via the inflow restriction 16. An outflow line 20 branches off from the valve control chamber 17 via an outflow restrictor 18 and a control valve 19.

In the closed position of the nozzle unit 2, the control valve 19 is open, so that the fuel pumped into the inlet line 11 by the pump device (not shown) is supplied to the inlet throttle 16.
To the valve control chamber 17, and from this valve control chamber 17 to the outlet line 20 via the outlet throttle 18.

The actuator unit 3 is operated to operate the nozzle unit 2, whereby the control valve 19 is closed. The fuel pumped by the pump device can no longer flow out at that time, so that a pressure builds up in the valve control chamber 17, the inlet line 11, the annular chamber 12, the transverse bore 13, the longitudinal bore 14 and the pressure chamber 15. You. Various forces act on the nozzle needle 6 of the nozzle unit 2.

On the other hand, the nozzle needle 6 is pressed to the closed position by the spring force of the nozzle spring 21. Due to the pressure formed in the valve control chamber 17 acting on the face 6a at the rear end of the nozzle needle 6, a further control force acts on the nozzle needle 6 and pushes it to the closed position. Finally, the pressure formed in the pressure chamber 15 acts on the surface 6b of the tip of the nozzle needle 6 to generate an operating force,
This operating force pushes the nozzle needle 6 to the open position.

The configured pressure causes the nozzle needle 6 to move toward the open position as long as the operating force exceeds the combined force of the spring force and the control force. The movement of the nozzle needle 6 in the direction of the open position ends when the configured pressure decreases to such an extent that the operating force is smaller than the combined force of the spring force and the control force.

When the nozzle needle 6 is moved toward the open position, the nozzle needle 6 is pulled up from the seal seat 8. As long as the dead stroke (hr) has not been overcome, fuel does not flow from the nozzle unit 2 through the metering opening 9 into the combustion chamber of the internal combustion engine. At the open position of the nozzle unit 2 within the dead stroke (hT), the pressure formed in the nozzle unit 2 is no longer generated in the seal seat 8, and the guide seat 22 between the outer peripheral surface of the nozzle needle 6 and the guide hole 5 is not provided. Has occurred.

As soon as the dead stroke (hT) is overcome, the metering opening 9 is opened, through which fuel can flow out of the nozzle unit 2. After overcoming the dead stroke (hT), a cross section is first opened between the seal seat 8 and the nozzle needle 6, which cross section is larger than the cross section of the metering opening 9. Therefore, the flow rate of the fuel flowing out of the opened nozzle unit is reduced by the cross section of the metering opening 9. In other words, the nozzle unit 2 of the metering valve 1 according to the present invention is formed as a Vario-duese without a seat valve.

Therefore, the nozzle unit 2 can take three different positions. In the closed position, the pressure chamber 15 is restricted upward by the surface 6 a of the tip of the nozzle needle 6, downward by the nozzle body 4, and laterally by the seal seat 8. In the open position of the nozzle unit 2, the pressure chamber 15 moves upward from the tip of the nozzle needle 6 and downward from the nozzle body 4 within the dead stroke (hT), and the pressure chamber 15 moves between the nozzle needle 6 and the guide hole 5. Guide seat 2 between
2 and the guide holes 5 limit the sides. At the open position of the nozzle unit 2, the pressure chamber 15 opens to the metering opening 9 outside the dead stroke (hT).

An annular leakage chamber 23 is formed on the inner peripheral surface of the guide hole 5 between the annular chamber 12 and the distal end 6 b of the pressure chamber 15. A leak pipe 24 branches off from the leak chamber 23 and opens to the outflow pipe 20. Based on the leak chamber 23, the annular chamber 12 and the leak chamber 23
The pressure generated in the nozzle unit 2 is generated only in the area of the guide gap. In the other region of the guide gap between the annular chamber 23 and the pressure chamber 15, only a very small leakage pressure occurs.

The nozzle body 4 of the metering unit 2 shown in FIGS. 1 and 2 has two circular metering openings 9 formed therein. In the open position, a plurality of metering openings 9a, 9b having different cross sections are arranged in an overlapping manner so that the flow rate of fuel flowing out of the nozzle unit 2 outside the dead stroke (hT) can be variably adjusted. It is also possible (see FIG. 3). Further, instead of the metering opening 9 having a circular cross section shown in FIG. 1 or FIG. 2, it is also possible to arrange a metering opening 9c having a vertically long cross section in the nozzle body 4 (see FIG. 4). . Depending on the opening stroke of the nozzle unit 2, a different flow rate of fuel can flow out of the nozzle unit 2 through the metering opening 9 c.

[Brief description of the drawings]

FIG. 1 is a metering valve according to the invention showing an advantageous embodiment;

FIG. 2 is a tip of a nozzle unit of the present invention showing an advantageous embodiment;

FIG. 3 is a front end of a nozzle unit of the present invention having a plurality of metering openings arranged in an overlapping manner.

FIG. 4 is a front end of a nozzle unit of the present invention having a vertically long metering opening.

[Explanation of symbols]

1 metering valve, 2 nozzle unit, 3 actuator unit, 4
Nozzle body, 5 Guide hole, 6 Nozzle unit, 6a and b surfaces, 8 Seal seat, 9 Metering opening, 10 Tightening nut, 11 Inflow line, 12 Annular chamber, 13 Lateral hole, 14 Longitudinal hole, 15 Pressure Chamber, 16 inlet throttle, 17 valve control chamber, 18 outlet throttle, 19 control valve, 20 outlet line, 21 nozzle spring, 22 guide seat, 23 leak chamber, 24 leak line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02M 47/00 F02M 47/00 P 47/02 47/02 61/10 61/10 Q

Claims (13)

[Claims] 1. A metering unit for metering a liquid or a gas, comprising a nozzle body (4) and a guide hole (5) of the nozzle body (4) between an open position and a closed position. And a nozzle needle (6) movably guided by the nozzle needle (6) so that at least one metering opening (9) opening in the guide hole (5) is controlled by the nozzle needle (6). And the nozzle needle (6
) Is in a closed position, the nozzle needle (6) is placed in the seal seat (8) of the nozzle body (4), the nozzle needle (6) is opened inward and has a dead stroke (hT). A metering unit for metering a liquid or gas. 2. The metering unit according to claim 1, wherein the nozzle unit is designed as a fuel injection nozzle for a fuel injection system of an internal combustion engine. 3. The metering unit according to claim 2, wherein the nozzle unit is formed as an injector for a common rail injection system of the internal combustion engine. 4. An inflow pipe (11) is formed in the nozzle body (4), and the inflow pipe (11) is formed in an annular chamber (12) formed on the inner peripheral surface of the guide hole (5). ), The annular chamber (12) being connected to a lateral hole (13) formed in the nozzle needle (6) at least in the closed position of the nozzle unit (2). A longitudinal hole (14) formed in the nozzle needle (6) branches off from the lateral hole (13), and the longitudinal hole (14) is connected to the nozzle needle (6).
4. The metering unit according to claim 1, wherein the metering unit opens into the pressure chamber at the end of the metering unit. 5. A pressure chamber (15) in a closed position of the nozzle unit (2) upwards by a nozzle needle (6) and downwards by a nozzle body (4) and a sealing seat (8). 5. Laterally restricted by
Metering unit as described. 6. The pressure chamber (15) is directed upwards by a nozzle needle (6) inside a dead stroke (hT) and downwards by a nozzle body (4) in the open position of the nozzle unit (2). And is laterally limited by the inner wall of the nozzle body (4) in the region of the guide hole (5) and the guide seat (22) between the guide hole (5) and the nozzle needle (6). A metering unit according to claim 4. 7. The pressure chamber (15) opens into the at least one metering opening (9) of the nozzle needle (6) outside the dead stroke (hT) in the open position of the nozzle unit (2). A metering unit according to any one of claims 4 to 6. 8. The control as claimed in claim 4, wherein the annular chamber (12) is limited by an outer wall outside the dead stroke (hT) in the open position of the nozzle unit (2). Quantity unit. 9. An annular leakage chamber (23) is formed on the inner peripheral surface of the guide hole (5) between the annular chamber (12) and the pressure chamber (15). 9. The metering unit according to claim 1, wherein the leak line (24) is branched. 10. A plurality of first metering openings (9a) are formed in the nozzle body (4), and a plurality of second metering openings (9b) are provided above the first metering openings (9a). 10. The dosing unit according to claim 1, wherein the dosing unit is formed and the first dosing opening (9a) has a smaller cross-section than the second dosing opening (9b). . 11. A plurality of metering openings (4) having a longitudinal cross section in a nozzle body (4).
9. The metering unit according to claim 1, wherein the longitudinal axis of the cross section extends parallel to the longitudinal axis of the nozzle unit. 9. 12. A metering valve (1) for metering a liquid or gas, comprising:
In a type in which a nozzle unit (2) and an actuator unit (3) for operating the nozzle unit (2) are provided, the nozzle unit (2) is any one of claims 1 to 11. A metering valve for metering a liquid or gas, characterized in that the metering valve is formed as a nozzle unit (2) having the configuration described in (1). 13. The valve control chamber (11) has an inlet line (11) connected via an inlet throttle (16).
17), the outflow restrictor (18) and the control valve (1) from the valve control chamber (17).
13. The metering valve according to claim 12, wherein the outlet line branches off via 9).