EP1218630A2

EP1218630A2 - Injection valve, in particular for a common rail injection system

Info

Publication number: EP1218630A2
Application number: EP00975823A
Authority: EP
Inventors: Hermann Golle
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-05
Filing date: 2000-10-04
Publication date: 2002-07-03
Also published as: WO2001025608A3; WO2001025608A2; AU1381101A; CN1377444A; CZ20021171A3; DE19947772A1

Abstract

The invention relates to an injection valve (1), in particular for common rail injection systems, which comprises a control cylinder (7) directly connected to a nozzle needle, which can be moved in the longitudinal direction inside a control cylinder (12) and with which a control space (6) is enclosed. Said control space is connected via an inlet throttle (18) to a fuel high pressure source and is connected to a low pressure space via an outlet throttle (11), whereby the outlet throttle (11) is connected to an outlet control valve (10). Said outlet control valve is connected to a positioning member which, in turn, is connected to a control unit that can be opened and closed. The aim of the invention is, by involving a simple construction with regard to manufacturing techniques, to improve the hydraulic control system in order to be able to execute precise and rapid control processes, in particular, in future injection processes (multijet system) that are even more subdivided. To this end, an inlet control valve (13) is provided, with which the inlet throttle (18) can be opened and closed counter to the outlet control valve (10).

Description

Injection valve, in particular for combination rail

injection

The invention relates to an injection valve, in particular for common rail injection systems, with a control piston which is connected directly to the nozzle needle, which is arranged to be longitudinally movable in a control cylinder and includes a control chamber with the latter, which has an inlet throttle with a high-pressure fuel source and an outlet throttle is connected to a space of lower pressure, the outlet throttle being openable and closable with an outlet control valve which is connected to an actuator connected to a control unit.

Valves of the type mentioned initially work with a fuel pressure of 1300 bar or higher (in the case of the diesel process). The injection quantity is measured by a hydraulic control depending on the engine parameters. The system is controlled by fast electromagnets or piezoceramic actuators.

The technical status and the disadvantages of the current hydraulic control are described with reference to the drawing according to FIG. 6, which shows a longitudinal section through a conventional injection valve of a common rail system.

The fuel at high pressure is supplied to the injection valve body 1 through the inlet connection 2. This fuel pressure is applied to the injection nozzle 4 on the one hand via the supply duct 3 and to the control chamber 6 on the other hand via the inlet throttle 5. The control piston 7 is in direct contact with the nozzle needle 8 in the injection nozzle 4.

As a result of the larger area ratio of the control piston 7 to the pressure shoulder of the nozzle needle 8, the injection nozzle 4 remains closed and no injection takes place. In order to initiate the injection, the control valve 10 is opened by the electrical system (magnetic or piezoceramic), represented here by the bolt 9, and thus the control chamber 6 is relieved via the outlet throttle 11. Thus, the high fuel pressure acting on the pressure shoulder of the nozzle needle 8 can raise the same, whereby the injection is initiated. This takes place until the electrical system or a spring force closes the control valve 10 and the fuel flowing in via the inlet throttle 5 increases the pressure in the control chamber 6 again, thereby closing the nozzle needle 8. So the closing of the nozzle needle 8 and thus the termination of the injection process is hydraulically supported.

It is disadvantageous here that after opening the outlet throttle 11, that is to say during the injection process, the inlet throttle 5 remains open in its full size, so that when the control chamber 6 is relieved of stress, fuel which is highly charged flows into this control chamber 6. This prevents the system from reacting quickly and leads to considerable energy loss. This inexact working principle alone results in hydraulic control losses of up to 15% of the total power loss.

Designs of injection valves have already been proposed with which the disadvantages mentioned are to be eliminated.

Such designs as. B. DE 197 16 220, have transverse double-seat valves and, in addition to high manufacturing costs, also have complicated control systems.

In other cases, such as B. DE 44 17 950, the control valve is arranged outside the actual injection valve and the nozzle needle consists of one piece with other components, so it is not suitable for fast injections. Other known designs also have complicated control systems.

Injectors for com on-rail systems are required in large quantities. They must therefore be technologically clear and simple.

It is an object of the invention to improve the hydraulic control system with a construction that is simple in terms of production technology, in order to be able to carry out precise and fast control processes, particularly in the case of the injection processes (multijet system), which will be even more divided in the future.

According to the invention, this object is achieved in that an inlet control valve is provided with which the inlet throttle closes and is opposite to the outlet control valve.

Particularly advantageous embodiments of the invention have the features of subclaims 2 to 9.

The invention is illustrated below using three exemplary embodiments. The drawings show:

1 shows a longitudinal section through the injection valve, the control preferably being carried out by an electromagnet,

2 shows the upper section from FIG. 1 when no injection takes place,

3 shows the same section when an injection takes place,

4 shows the same section when the injector is controlled by a piezoceramic actuator,

5 the upper section analogously to FIGS. 2 and 3 changed position of the inlet control valve and

Fig. 6 shows a longitudinal section through a conventional injection valve.

In the first exemplary embodiment, FIG. 1 shows the injection valve body 1, in which a cylinder 12 is inserted. A control piston 7 and the exhaust throttle 11 with the exhaust control valve 10 are arranged in this cylinder 12. The control piston 7 is connected directly to the nozzle needle 8 in the injection nozzle 4.

According to the invention, a control valve is also arranged in the inlet throttle, the inlet control valve 13. A specially designed adjusting pin 14, which acts as an actuator, actuates both valves at the same time. The outlet control valve 10 is controlled directly, while the inlet control valve 13 is actuated by means of a pressure pin 15 from a control edge 16 located on the adjusting pin 14. One and the same adjusting pin 14 thus controls both control valves in the simplest way.

2 to 4, the upper section of the injection valve is shown enlarged. The high-tension fuel is fed through the inlet connection 2 via the feed channel 3 on the one hand to the injection nozzle 4 and on the other hand to the valve chamber 17 of the

Inlet control valve 13 supplied. In the illustration

2, no injection is to take place. Accordingly, the adjusting pin 14, loaded by a spring force, holds the

Exhaust control valve 10 is closed, while the control edge 16 holds the intake control valve 13 open via the pressure pin 15. The high hydraulic pressure is thus above the channel

18 in the control chamber 6 and the control piston 7 keeps the injection nozzle 4 closed.

If, as in Fig. 3, an electromagnet has lifted the setting pin 1 4, this opens Exhaust control valve 10 and the control chamber 6 including the channel 18 are relieved. At the same time, the control edge 16 releases the pressure pin 15 and, due to the drop in pressure in the control chamber 6, the inlet control valve 13 closes abruptly, supported by a first pressure spring 19. Thus, no high-tension fuel can flow into the control chamber 6, so that the load is relieved very quickly. The hydraulic control of the system therefore works more precisely, the hydraulic loss control amount is significantly reduced. The fuel flowing out of the control chamber 6 passes through the (or more) drain hole 20 into a low-pressure space, in which the leakage fuel from the injection nozzle 4 and the pairing of control piston 7 / cylinder 12 also flows back via the return channel 21.

To complete the injection, the adjusting pin 14 is moved into its lower position. It closes the outlet control valve 10 and, via its control edge 16 and the pressure pin 15, the inlet control valve 13 is opened at the same time. The high hydraulic pressure suddenly loads the control piston 7 again via the channel 18 and the injection nozzle 4 is closed very quickly, as is necessary for the completion of the injection.

4 shows the second exemplary embodiment with a piezoceramic actuator as the control unit. The outlet control valve 10 is designed as an inward opening valve which is opened against a second compression spring 22 by a tappet 23. The piezoceramic actuator 24 is arranged in a relaxed manner towards the center of the injection valve body 1. A two-armed lever, preferably designed as an angle lever 25, is connected between the actuator tappet 26, which serves as an actuator, and the control valves 10 and 13 such that both valves are actuated alternately in the previously described sense. In the “no injection” state, the outlet control valve 10 is closed and the inlet control valve 13 is open; the high hydraulic working pressure is present in the control chamber 6 via the channel 18. in the In the “injection” state, the actuator tappet 26 has actuated the angle lever 25 in such a way that the exhaust control valve 10 is opened and the intake control valve 13 is closed, as a result of the actuator being desaxed. At the end of the injection, the actuator tappet 26 releases the angle lever 25, the valve 10 is closed and the valve 13 is opened. A spring of any type, not shown in FIG. 4, can assist the return of the angle lever 25.

The control valves 10 and 13 can be designed differently from the representations in FIGS. 1 to 4. Thus, the inlet control valve 13 and the pressure pin 15 can also be summarized, for. B. be designed as a guided cone seat valve. The outlet control valve 10 and the tappet 23 can also be designed as a single component.

5, the position of the inlet control valve 13 is changed so that the head of the injection valve can be kept narrower. This is advantageous for particularly small installation conditions. The pressure pin 15, including the inlet control valve 13, is arranged parallel to the adjusting pin 14 and the high-tension fuel is guided here through the angled end of the supply channel 3 to the valve chamber 17. The channel 18 consists of two bores running at an acute angle to one another. The method of operation corresponds to the sequence described in FIGS. 2 and 3. A spring force holds the outlet control valve 10 closed over the adjusting pin 14. At the same time, the pressure pin 15 is pressed into its lower stop position via a bridge 27 and keeps the inlet control valve 13 open. Thus, the high hydraulic pressure from the supply duct 3 is present in the control chamber 6 via the open inlet control valve 13 and the duct 18 and keeps the nozzle needle closed. If the adjusting pin 14 is raised by the e-magnet, the outlet valve 10 opens and the inlet control valve 13 closes. High-tension fuel cannot flow into the control room 6; This is relieved very quickly. An injection takes place until the adjusting pin 14 Exhaust valve 10 closes and at the same time opens the inlet control valve 13 via the pressure pin 15. Suddenly high-tension fuel can then flow into the control chamber 6 and quickly end the injection.

The bridge 27 can be equipped with certain resilient properties. The stop 28 of the pressure pin 15 also represents a seal of the pressure pin when the inlet control valve 13 is open.

Injector, especially for common rail

injection

LIST OF REFERENCE NUMBERS

Injection valve body Inlet connection Inlet duct Injector nozzle Inlet throttle Control chamber Control piston Nozzle needle Bolt Exhaust control valve Outlet throttle Cylinder Inlet control valve Adjusting pin Push pin Control edge Valve chamber Channel 1

Claims

Injection valve, especially for common rail injection systems

1. In pr it z vent i 1, especially for common rail injection systems, with a directly with the nozzle needle in

Connected spool in one

Control cylinder is arranged to be longitudinally movable and includes with this a control space, which has a

Inlet throttle is connected to a high-pressure fuel source and via an outlet throttle to a space of lower pressure, the outlet throttle being connected to a

Exhaust control valve, which is connected to an actuator connected to a control unit, can be opened and closed so that an intake control valve (13) is provided, with which the intake throttle (5) is connected to the

Exhaust control valve (10) is opposite closing and evident.

2. Injection valve according to claim 1, so that the actuator (14; 26) is at the same time in a controlling operative connection with the inlet control valve (13).

3. Injection valve according to claim 1, so that a second actuator (15) is connected to the inlet control valve (13) in a controlling manner.

4. Injector according to one of claims 1 to 3, d a d u r c h g e k e n n z e i c h n e t that the

Inlet control valve (13) through the actuator (14; 26) via a control edge (16) located on the actuator (14) or a bridge (27) can be actuated directly or via a two-armed angle lever (25) connected downstream of the actuator (26).

5. Injection valve according to one of claims 1 to 4, characterized in that the actuator is designed as a first piston (14) in a first actuating cylinder, in the cylinder space on the one hand a drain hole (20) protrudes and on the other hand has a connection to a second control cylinder, which can be opened or closed by the actuator, and that a second control piston (15) is arranged in the second control cylinder and is connected in a controlling manner to the inlet control valve (13).

6. Injection valve according to one of the claims Ibis 5, d a d u r c h g e k e n n z e i c h n e t that the inlet control valve (13) in the path from the supply channel (3) extended into the cylinder (12) and the channel (18) leading to the control chamber (6) is switched on.

7. Injection valve according to one of claims 1 to 6, that a piezoceramic actuator (24) is used as the control unit.

8. Injector according to one of claims 3, 6 or 7, that the second actuator (15) is connected to a second control unit which is designed as a second piezoceramic actuator.

9. Injection valve according to claim 7, so that the axis of the actuator (24) is arranged in a desaxed manner towards the system center of the injection valve body (1).