WO2009130063A1

WO2009130063A1 - Injector

Info

Publication number: WO2009130063A1
Application number: PCT/EP2009/051233
Authority: WO
Inventors: Matthias Burger; Nadja Eisenmenger; Hans-Christoph Magel
Original assignee: Robert Bosch Gmbh
Priority date: 2008-04-21
Filing date: 2009-02-04
Publication date: 2009-10-29
Also published as: DE102008001281A1

Abstract

The invention relates to a transitional space (19) disposed between the output side of a control valve (13) and a discharge space (5), communicating with the discharge space only via an attenuating path (20).

Description

Technical area

The invention relates to an injector for injecting fuel into a combustion chamber of an internal combustion engine according to the preamble of claim 1.

Such injectors are used as standard in so-called common-rail systems.

Although such systems, including the associated injectors, have proven useful, improvements remain desirable. For on the one hand occur when closing the valve member of the control valve due to the fast switching movements bounce, on the other hand, unwanted vibrations can be generated when opening this valve member on the low pressure side of the injector.

Disclosure of the invention

It is therefore an object of the invention to provide an injector with particularly good switching behavior.

This object is achieved in an injector of the type specified by the characterizing features of claim 1.

The invention is based on the general idea to dampen the closing movement of the valve member of the control valve. The fact is exploited that the Valve member of the control valve within a formed by the transition space and the input side of the control valve total space in the manner of a displacer, the closing stroke of the valve body of the control valve against the caused by the throttle points of the transition space back pressure in the aforementioned total space and accordingly delayed, ie attenuated, is ,

According to an advantageous embodiment of the invention can be provided that the control valve in a basically known manner has an annular valve seat and a cooperating sleeve-shaped valve body, wherein the transition space is arranged concentrically to the valve body.

In this case, the valve seat of the control valve can be arranged on a valve seat body which is arranged in the injector body as a partition wall between the inflow space and the outflow space. According to a particularly preferred embodiment of the invention, the transitional space may have an opening into the outflow pressure relief valve, wherein the closing body may be formed as displaceable on the sleeve-shaped valve body of the control valve sleeve.

Moreover, reference is made to the claims and the following explanation of the drawing with regard to preferred features of the invention, are explained in detail with reference to the particularly preferred embodiments of the invention.

Protection is claimed not only for expressly shown combinations of features but also for any combinations of the illustrated or specified individual features.

Explanation of the drawing

In the drawing shows

1 is a schematic sectional view of a first embodiment of the invention,

Fig. 2 is a corresponding representation of a modified embodiment and

Fig. 3 is a sectional view of another embodiment of the invention. The fuel injector of Fig. 1 has in a basically known manner a multi-part injector body 1, the interior of which is firmly clamped by a substantially disc-shaped valve seat body 2, which is clamped on a step in the interior of the injector body 1 by means of an externally threaded ring 3 screwed into a corresponding internal thread of the injector body 1 is subdivided into an inlet space 4 and a discharge space 5 for fuel. The feed chamber 4 is permanently connected to a high-pressure source for fuel, in particular a common rail, and is accordingly under high pressure. The drain chamber 5 is constantly connected to a relatively pressureless return line 6 for fuel, so that the drain chamber 5 is virtually depressurized. The interior of the inlet chamber 4 communicates with the interior of a nozzle body 7, which in a combustion chamber of an internal combustion engine opening nozzles 8, which are controlled by a nozzle needle 9. The nozzle needle 9 has a plunger-like end remote from the nozzle, which works as a displacer in a control chamber 10 which is accommodated in a cylinder arranged on the valve seat body 2 in the inlet chamber 4. Moreover, the nozzle needle 9 is acted upon by a coaxial with the needle axis arranged helical compression spring 11 in the nozzle 8 closing direction.

The control chamber 10 is connected via a first throttle Dl to the inlet chamber 4 and via a second throttle D2 with a valve chamber 12 of a control valve 13. This control valve 13 has a sleeve-shaped valve body 15 slidably guided on a stationary plunger rod 14 which is controlled by means of a ring-shaped electromagnet 16 arranged concentrically with the plunger rod 14 and by means of a closing spring 17 arranged concentrically with the plunger rod 14, which in the example shown is designed as a helical compression spring is tensioned on the associated seat 18 resting on the valve seat body 2 closed position.

On the side facing the drain chamber 5 side of the valve seat body 2, a sleeve-shaped valve body 15 concentric cylinder-like housing is arranged, which encloses an annular transition space 19 which communicates with the drain chamber 5 via arranged in the aforementioned housing throttle bores 20.

The injector shown in Fig. 1 operates as follows: - A -

When the nozzle needle 9 occupy the closed position shown in FIG. 1 or should remain in this closed position, the control valve 13 is kept closed or closed. This is the same pressure in the control chamber 10 as in the inlet chamber 4, and the helical compression spring 11 thus provides the nozzle needle 9 in the closed position. The closed position of the control valve 13 is adjusted or held by the fact that the electromagnet 16 is switched or held electrically de-energized.

If now at the beginning of an injection phase, the nozzle needle 9 is to be placed in their nozzles 8 releasing open position, the solenoid 16 is electrically energized, so that the sleeve-shaped valve body 15 arranged armature assembly 21 magnetically attracted by the solenoid 16 and accordingly the valve body 15 from the seat 18th is lifted. Thus, the control chamber 10 receives via the throttle D2, the valve chamber 12, the transitional space 19 and the throttle bores 20 connection with the relatively pressureless drain space 5, i. the pressure in the control chamber 10 assumes vanishing values, so that the high pressure in the inlet chamber 4 and in the nozzle body 7 sets the nozzle needle 9 against the closing force of the helical compression spring 11 in the open position. At the same time fuel is injected through the nozzles 8 in the (not shown) combustion chamber of the internal combustion engine.

Within the overall space formed by the transitional space 19 and the valve space 12, the sleeve-shaped valve body 15 functions as a displacer, wherein the volume of the total space 12, 19 is increased during the opening stroke of the valve body 15. The associated pressure reduction in the total space 12,19 leads to a more or less large approximation of the pressure to the vanishing pressure of the drainage chamber 5, i. There is a controlled pressure reduction, so that the excitation of unwanted pressure oscillations is largely avoided.

When the solenoid 16 is de-energized to close the control valve 13, the sleeve-shaped valve body 15 must displace fuel from the total space 12,19 through the throttle bores 20 in the drain chamber 5 at its closing stroke. According to the throttle resistance of the throttle bores 20, the valve body 15 must work against a more or less large hydraulic back pressure during its closing stroke, so that the closing stroke of the valve body 15 is damped. A further damping of the closing stroke occurs in its final phase, because with increasing approach of the valve body 15 to its seat 18 is formed between the facing Areas of valve body 15 and seat 18 is a narrowing nip 22, from the hydraulic medium, ie fuel must be displaced, the displacement is delayed because the fuel can only relatively slowly escape from the nip due to its viscosity. As a result, a delayed approach of the valve body 15 is achieved to its closed position. This is equivalent to saying that the pressure in the control chamber 10 comparatively slowly reaches the value necessary for closing the nozzle needle 9. As a result, 9 unwanted pressure oscillations in the hydraulic medium of the inlet chamber 4 and the drain chamber 5 are largely avoided or attenuated in this way, even during the closing process of the nozzle needle. Furthermore, it is advantageous that a rapid outflow of fuel from the transitional space 19 into the discharge space 5 is avoided by the throttle action of the throttle bores 20. This has the advantage that at the end of the closing movement of the valve body 15 or at the beginning of its opening movement, ie when only a very narrow annular gap is opened between valve seat 18 and valve body 15, only comparatively low flow velocities can occur within this annular gap and thus An undesirable cavitation of the fuel is avoided.

The embodiment of Fig. 2 differs from the embodiment of Fig. 1 essentially in that the transitional space 19 is connected to the drain chamber 5 on the one hand via the throttle 20 and on the other hand via a pressure relief valve 23.

In this way, the achievable in the transition space 19 maximum pressure is limited. In the example shown, the pressure relief valve 23 has a valve body serving as a closing ball, which is stretched by a leaf spring-like closing spring which is fixed to the valve seat body 2 in the closed position.

Otherwise, the above statements regarding FIG. 1 apply to the embodiment of FIG. 2.

The embodiment of Fig. 3 differs from the embodiments of Figs. 1 and 2 essentially in that the housing of the transitional space 19 forms the closing body of a pressure control valve. As shown in FIG. 3, a further sleeve-shaped valve element 24 is slidably disposed on the outer circumference of the sleeve-shaped valve body 15 of the control valve 13, which is arranged by a closing spring 25 designed as a helical compression spring coaxial with the valve body 15 and between the mutually facing sides of the valve element 24th and the Anchor assembly 21 is clamped, is urged into the closed position, wherein the valve element 24 cooperates with a formed on the valve seat body 2 annular valve seat 26. In this embodiment, therefore, a controllable back pressure arises when opening the valve body 15 of the control valve 13 in the transitional space 19.

Furthermore, FIG. 3 shows by way of example that the stationary plunger rod 14, which shuts off the valve space 12 within the sleeve-shaped valve body 15, can be formed separately from a bottom 27 closing the injector body 1 at the upper end in FIG. 3. In the example shown, an annular disk is formed at the upper end of the plunger rod 14, which forms the stationary abutment of the closing spring 17 of the valve member 15 and is thus stretched by the closing spring 17 against the bottom 27 and thus the plunger rod 14 perpendicular to the bottom 27 aligns.

Furthermore, the bottom 27 by screw adjustment in the injector body 1 in Fig. 3 displaced in the downward direction, such that the solenoid assembly 16 against a provided with radial openings cylinder ring 28 is axially pushed, in which case the cylinder ring 28, the disk-shaped valve seat body 2 against a facing ring stage in Interior of the injector body 1 spans. The bottom 27 thus serves, on the one hand, to close the drainage space 5 and, on the other hand, to fix the electromagnet arrangement 16 as well as the cylinder ring 28 and the valve seat body 2 in the injector body 1.

Claims

claims

1. injector for injecting fuel into a combustion chamber of an internal combustion engine, with a at least one injector (8) controlling, substantially needle-shaped valve member (9) which is arranged longitudinally displaceable with a working as a displacer end in a control chamber (10) which over an input-side throttle arrangement (D1) with an inlet chamber (4) for fuel supplied at high pressure and via an output-side throttle arrangement (D2) communicates with the input side of a control valve (13) which is connected on the output side to a discharge chamber (5) for relatively pressureless fuel, characterized in that a transitional space (19) hydraulically between the output side of the control valve (13) and the outflow space (5) is connected and connected to the outflow space (5) only via a throttle effective path, and that when the control valve (13) whose valve body (15) within one of the input side (12) of the Steue rventils (13) and the transition space (19) formed space displacer works.

2. An injector according to claim 1, characterized in that the control valve (13) has an annular valve seat and a cooperating sleeve-shaped valve body (15), and that the transition space (19) concentric with the sleeve-shaped valve body (15) is arranged.

3. Injector according to claim 2, characterized in that the valve seat of the control valve (13) is arranged on a valve seat body (2) which is arranged in the injector body (1) as a partition wall between the inlet space (4) and the discharge space (5).

4. Injector according to claim 2 or 3, characterized in that the sleeve-shaped valve body (15) of the control valve (13) on a stationary plunger rod (14) is displaceably guided, the interior of the sleeve-shaped valve body (15) at a predetermined axial distance from the associated Valve seat (18) closes.

5. An injector according to claim 4, characterized in that the plunger rod (14) on a bottom (27) of the injector body (1) coaxially to an annular solenoid assembly (16) is arranged, with one on the valve body (15) of the control valve (13 ) arranged armature assembly (21) magnetically cooperates.

6. An injector according to claim 5, characterized in that the valve body (15) of the control valve (13) by a closing spring (17) is acted upon, the stationary abutment is formed as an end-side disc of the plunger rod (14) and of the closing spring (17). is tensioned against a bottom (27) of the injector body (1).

7. An injector according to one of claims 1 to 6, characterized in that at the transition space (19) in the outflow space (5) opens out pressure relief valve (23) is arranged.

8. Injector according to one of claims 1 to 7, characterized in that the transition space communicates via a pressure regulating valve with the discharge space (5).

9. An injector according to claim 8, characterized in that the valve body (24) of the pressure regulating valve is formed as on the valve body (15) of the control valve displaceable sleeve body.