EP2100026A1

EP2100026A1 - Fuel injector having a solenoid valve with a spherical seat

Info

Publication number: EP2100026A1
Application number: EP07821236A
Authority: EP
Inventors: Nadja Eisenmenger; Hans-Christoph Magel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-12-04
Filing date: 2007-10-12
Publication date: 2009-09-16
Anticipated expiration: 2027-10-12
Also published as: DE502007006059D1; CN101548092B; EP2100026B1; WO2008068093A1; DE102006057025A1; ATE492719T1; CN101548092A

Abstract

The fuel injector (10) has an injecting valve element (42) operated via pressure discharge of a control chamber (36), which is subjected with a system pressure. The pressure discharge of the control chamber is made by a pressure-compensating magnetic valve (22), whose valve element (62) opens or locks a valve seat (80). The valve element or a piece of valve exhibits a spherical surface (86). The valve element is guided at a pressure pin, and a pressure-compensating area (78) is limited with the valve element.

Description

description

title

FUEL INJECTOR WITH SOLENOID VALVE WITH BALL SEAT

State of the art

An injector for injecting fuel into a combustion chamber of an internal combustion engine, in which an injection valve member is actuated via a solenoid-operated control valve, is known from EP-A 1 612 403. With the aid of the control valve, a drain throttle from a control room can be closed or released in the fuel return. The control chamber is bounded on one side by a control piston with which an injection valve member is actuated, which releases at least one injection opening into the combustion chamber of the internal combustion engine or closes it. The outlet throttle is received in a body, which is provided on the side facing away from the control chamber with a tapered valve seat. In this valve seat, a closing element is adjustable, which is connected to the armature of the solenoid valve. For this purpose, an edge is formed on the closing element, which is provided against the conically shaped seat. The closing element moves on an axial rod, which is integrally connected to the body in which the drainage throttle is formed. In order for the valve to close in a liquid-tight manner, it is necessary to produce high-precision surfaces and to provide a highly accurate fit of the closure member on the axial rod, to prevent the closure member from tumbling and canting thereby not fully closing the seat.

At z. B. on high-pressure accumulator injection systems (common rail) used fuel injectors z. B. stroke-controlled injectors are used, which are operated by means of a solenoid valve to control the pressure in a control room. The preferably needle-shaped injection valve member is z. B. controlled by a servo control room. The solenoid valve is usually not pressure balanced and therefore requires high spring forces, high magnetic switching forces and due to the size of spring and magnet large space. A disadvantage of such solenoid valves is the fact that there are severe restrictions on the sequence of multiple injections. conditions so that very short successive injection intervals can not be realized.

Pressure compensated solenoid valves typically require much smaller spring forces, hence smaller magnetic forces to effect opening, as well as smaller valve lifts, thus allowing faster shift times. By means of this type of solenoid valves, a multiple injection capability can be improved. However, these pressure-balanced designed valves require a high-pressure-tight guide and a linearly extending sealing edge, which correspond to the guide diameter of the valve member, which allows the pressure balance of the solenoid valve only.

Critical in the pressure balanced solenoid valves, however, is the circumstance that a wear on a sealing edge sets in the course of their operating time, since the mechanical load of a linearly extending seat edge when closing the preferably needle-shaped injection valve member is very large. Furthermore, the wear is supported by the fact that impurities come to a greater extent directly to the seat edge. This leads over the operating time of the solenoid valve to wear, which affects the function of such a trained solenoid valve not insignificant.

Disclosure of the invention

In the solution according to the invention, a pressure-balanced solenoid valve is proposed, wherein the preferably needle-shaped valve member has a seat with respect to adjusting mechanical wear due to removal of material or deformation of a solid ball seat. As a valve seat of the present invention proposed solenoid valve with ball seat is formed on the valve sealing point, ie the seat of the valve member, a ball seat. The ball seat can be z. B. represent by a hemispherical configuration of the seat of the valve member facing the end of the valve member. The Z. B. hemispherical end of the valve member may be funnel-shaped, such. B. as a conical seat, trained seat in a valve piece. In addition, it is also possible, instead of the conical surface in the valve piece to form this conical surface at the end of the valve member and form the valve piece formed, cooperating with the valve member hemispherical. Both designs of a ball seat are possible. Preferably, the needle-shaped valve member is guided with an inner pressure pin loosely mounted in an actuator housing, whereby a pressure equalization can be achieved.

If the solenoid valve is provided with a ball seat, so z. B. a compensation of parallelism errors between the preferably needle-shaped valve member and a seat body, d. H. z. B. the valve piece, follow, so that thereby favorable multi-part valve design variants can be realized.

A further improvement is achieved by the connection of the ball seat proposed according to the invention with a small compression stage which is effective in the closing direction. By acting in the closing direction pressure stage, a hydraulic force acting on the valve member closing force is generated, whereby a bouncing is reduced in the valve closing, which in turn has beneficial effects on the self-adjusting wear, as occur during bouncing mechanical peak loads. The damping behavior when closing the solenoid valve is improved by the effective pressure in the closing direction, since in the closed state of the seat of the preferably needle-shaped valve member a hydraulic closing force builds up, which prevents reopening of the preferably needle-shaped valve member. On the one hand, this permits optimized valve tuning and, on the other hand, improves the multiple injection capability of the fuel injector, which is actuated by the solenoid valve having a ball seat proposed by the invention.

In addition, a damping chamber can be provided in the high-pressure region of the fuel injector, which on the one hand can advantageously optimize the speed at which the preferably needle-shaped valve member moves and, on the other hand, the bouncing properties and bouncing stresses caused by it with regard to the mechanical components. If the preferably needle-shaped injection valve member and an armature attracted by the solenoid of the solenoid valve are formed in one piece, a small moving mass can be achieved, and with optimized damping behavior, short distances of individual injection events can be realized, which favorably influences the multiple injection capability.

The inventively proposed pressure balanced solenoid valve with ball seat can be used to control injection systems, in particular advantageously as a control valve for a servo-controlled Kraftstoffinjektor which is actuated by means of a solenoid valve. In a particularly advantageous manner, the ball seat can be formed directly in the valve piece, in which a control chamber, in particular a servo control chamber, is located, and which closes a pressure chamber within the injector body of the fuel injector. This allows a simple and inexpensive construction of a fuel injector suitable in particular for high-pressure accumulator injection systems (common rail).

Short description of the drawing

With reference to the drawing, the invention will be described below in more detail. The sole FIGURE shows a section through the inventively proposed fuel injector, which is actuated by means of a solenoid valve which comprises a ball seat.

embodiments

From the drawing shows that a fuel injector 10 is acted upon via a pressure accumulator 12, in which a system pressure p _sys , with high-pressure fuel. The system pressure p _sys in pressure accumulator 12 is replaced by a not shown in the drawing high-pressure pumping unit, such. As a high-pressure pump, generated and passes from the pressure accumulator 12 via a high-pressure line 14 to the fuel injector 10. The high-pressure line 14 opens within an injector 16 and acts on a reference numeral 34 designated pressure chamber with system pressure p _sys stationary system pressure.

In addition to the injector housing 16, the fuel injector 10 further comprises a nozzle body 18, which is only indicated here, and an actuator housing 20, in which an actuator designed as a solenoid valve 22 is accommodated. The actuator housing 20 is closed by a housing cover 24. In the drawing, the housing cover 24 is provided with an external thread and can be screwed into a correspondingly formed internal thread of the actuator housing 20. Within the actuator housing 20, a magnetic core 26, a magnetic coil 28 enclosed by this, a magnetic core 26 supporting support sleeve 30 is received and part of a valve piece 32. The partially housed in the actuator housing 20 valve piece 32 limits the aforementioned pressure chamber 34, in which the from Pressure accumulator 12 outgoing high pressure line 14 opens.

In the valve piece 32, a control chamber 36 is formed, which is filled via an inlet throttle 38 from under system pressure p _sys pressure chamber 34 with fuel. The control chamber 36, which in the drawing is designed as a servo control chamber, is pressurized via an outlet throttle 40. ckentlastbar. The outlet throttle 40 is also formed in the valve piece 32 and opens into a valve space identified by reference numeral 84.

The system pressure p _sys applied via the inlet throttle 38 in the control chamber 36 acts on an end face 44 of a preferably needle-shaped injection valve member 42. The injection valve member 42 comprises a support disk 46 against which a closing spring 48 is supported. The support disk 46 opposite end of the closing spring 48 is supported on the valve piece 32 from.

From the pressurized space 34 acted upon by system pressure p _sys , an annular space 52 extends through the injector housing 16. Via the annular space 52, fuel under system pressure p _sys flows to a nozzle space designated by reference numeral 50, which is formed inside the nozzle body 18. From the annulus 52 passes under system pressure p _sys standing fuel via at least one throttle point 56, the z. B. may be formed as at least one bevel on the circumference of the preferably needle-shaped injection valve member 42, in the nozzle chamber 50th

The injection valve member 42 comprises a pressure stage 54 in the region in which it is enclosed in the nozzle body 18 by the nozzle chamber 50.

From the nozzle chamber 50, the fuel under system pressure p _sys flows through an annular gap to a seat 58 of the preferably needle-shaped injection valve member 42. In the illustration according to the drawing, injection openings 60 at the combustion-chamber-side end of the fuel injector 10 are closed by the injection needle member 42, which is placed in its seat 58 and is preferably needle-shaped.

At least one, preferably designed as a bevel throttle body 56 is at the periphery of the preferably needle-shaped injection valve member 42. About this at least one throttle point 56 of the system pressure p _sys standing annular space 52 and the nozzle chamber 50 are hydraulically connected to each other.

The solenoid valve 22 accommodated in the actuator housing 20 comprises a valve spring 70, which encloses a pressure pin 66. The valve spring 70 is supported on the underside of the housing cover 24. Preferably, the pressure pin 66 is loosely received in the actuator housing 20. The valve spring 70 acts on an upper end side of a valve member designed as a valve member 62. At this an anchor plate 64 is formed, which is disposed opposite to the solenoid coil 28 of the solenoid valve 22. The pressure pin 66 is formed in a diameter that represents a guide diameter 68 for the valve member 62. A lower end face of the pressure pin 66 bounded with the preferably needle-shaped valve member 62 a pressure compensation chamber 78. The pressure relief chamber 66 and the valve member 62 limited pressure compensation chamber 78 communicates via a flow connection 74 with a valve chamber 84 in connection. According to the embodiment of the present invention proposed fuel injector 10 shown in the drawing, the valve space 84 is bounded by a conical surface 82 in the valve piece 32 on the one hand and on the other hand by a spherical surface 86 at the lower end of the valve member 62. In the embodiment shown in the drawing, the spherical surface 86, which represents the ball seat, on the valve member 62 is executed. By the ball seat performing, spherical surface 86 on the valve piece 32 facing the end of the preferably needle-shaped valve member 62 can be achieved in an advantageous manner a compensation of parallelism errors between the valve member 62 and the seat body performing valve piece 32. In addition, can be realized by the inventively proposed arrangement favorable, multi-part valve bodies.

Reversing the ball seat shown in the drawing formed by the ball member 86 formed on the ball surface 86 and provided in the valve piece 32 conical surface 82, the conical surface 82 can also be formed on the valve member 62 and the spherical surface 86 on the valve piece 32 executed. Further, it is possible to realize both the valve member 62 and the valve piece 32 each spherical geometries.

Due to the fact that the guide diameter 68 substantially corresponds to the diameter of the ball seat formed by the spherical surface 86, the pressure balance of the solenoid valve 22 acts. With the valve design proposed according to the invention, a ball seat realized by the formation of a spherical surface 86 cooperates realized with a tapered surface 82, since the pressure pin 66 can be mounted independently of the valve seat 80 from the opposite side of the seating area. By reference numeral 74, a flow connection is identified, which connects the pressure equalization or damping chamber 78 with the valve space 84.

An embodiment of the fuel injector shown in the drawing is given by the fact that at the pressure pin 66, on which the preferred needle-shaped valve member 62 is guided, an effective pressure in the closing direction is generated. The effective in the closing direction of the preferably needle-shaped valve member 62 pressure stage can be achieved by increasing the guide diameter 68 of the loosely received in the actuator housing 20 pressure pin 66 with respect to the diameter of the given by the spherical surface 86 ball seat. By acting in the closing direction pressure stage, a hydraulic valve closing force is generated, whereby a bouncing of the Solenoid valve when closing the valve member 62 is reduced. The damping behavior when closing the valve member 62 can be improved by the pressure direction acting in the closing direction, given by the enlargement of the guide diameter 68 with respect to the diameter of the ball seat given by the spherical surface 86, since in the closed state of the ball seat a hydraulic Closing force builds up, which prevents reopening of the preferably needle-shaped valve member 62. This in turn allows for optimized valve tuning and an improvement in the multiple injection capability of the fuel injector 10 proposed according to the invention.

By the pressure equalization or damping chamber 78 communicating with the valve space 84 via the flow connection 74, the speed at which the valve member 62 opens can be optimized and the bouncing characteristics improved. If the preferably needle-shaped injection valve member 62 and the armature plate 64 are designed as a component, then a small mass to be moved, which leads to an optimized damping behavior by a damper throttle 76, which is arranged in the flow connection 74, resulting in very short distances be made possible with individual fuel injections in quick succession via the injection openings 30.

Advantageously, the ball seat realized by the spherical surface 86 is formed directly on the valve piece 32, which limits the control space 36 serving as a servo control room and separates from the pressure space 34 in the injector housing 16 under system pressure p _sys . The valve piece 32 is placed against the injector body 16 in a sealing manner via the support sleeve 30, the magnet core 26 resting thereon and the housing cover 24 with which the actuator housing 20 is closed.

The opening movement of the preferably needle-shaped valve member 62, which takes place when the solenoid valve 22 is energized, effects a pressure relief of the control chamber 36. The control quantity flowing out of the control chamber 36 when the ball seat is opened by the spherical surface 86 flows into the valve body Actuator 20 and is derived via a low-pressure side return 72 in the low pressure region of the fuel injection system. In the pressure relief of serving preferably as a servo control chamber control chamber 36 of the fuel injector 10 according to the embodiment shown in the drawing, retraction of the end face 44 of the needle-shaped injection valve member 42 into the control chamber 36. This flows through the open seat 58 of the injection valve member 42 via the at least a formed at the combustion chamber end of the fuel injector 10 opening 60 under system pressure p _sys standing fuel into the combustion chamber of the internal combustion engine.

The opening behavior of the preferably needle-shaped injection valve member 42 can be optimized by means of the throttle point 56, which is formed on its circumference and has at least one throttle point 56 which is preferably formed as a bevel. The at least one throttle point 56 formed on the circumference of the preferably needle-shaped injection valve member 42 provides a hydraulic connection with the annular space 52 under system pressure p _sys in the injector body 16 with the nozzle chamber 50 formed in the nozzle body 18 of the fuel injector 10.

Preferably, the pressure balanced solenoid valve 22 is used in injection systems for injecting fuel, in particular advantageously as a control valve for a servo-controlled Kraftstoffinjektor with a solenoid valve 22 which is used in high-pressure storage injection systems (common rail).

Claims

claims

A fuel injector (10) for injecting fuel into the combustion chamber of an internal combustion engine, wherein an injection valve member (42) is actuated via a pressure relief of a control chamber (36), which is acted upon by a system pressure p _sys , and the pressure relief of the control chamber (36) via a pressure-balanced solenoid valve (22) whose valve member (62) opens or closes a valve seat (80), characterized in that the valve member (62) or a valve member (32) has a spherical surface (86).

2. Fuel injector (10) according to claim 1, characterized in that a spherical surface (86) on the valve member (62) is executed, which with a conical surface (82) in a valve piece (32) forms a valve seat (80).

3. fuel injector (10) according to claim 1, characterized in that the spherical surface (86) in the valve piece (32) is executed, which with a conical surface (82) having valve member (62) forms the valve seat (80).

4. fuel injector (10) according to claim 1, characterized in that the valve member (62) is guided on a pressure pin (66) and limited with this a pressure compensation chamber (78).

5. Fuel injector (10) according to claim 4, characterized in that the valve member (62) has a flow connection (74) between the pressure equalization chamber or

Damper chamber (78) and the valve seat (80).

6. Fuel injector (10) according to claim 5, characterized in that in the flow connection (74) a throttle point (76) is executed.

7. fuel injector (10) according to claim 1, characterized in that the valve member (62) is guided on a pressure pin (66) whose guide diameter (68) corresponds to an inner diameter of the valve member (62).

8. fuel injector (10) according to claim 1, characterized in that the valve member (62) is guided on a pressure pin (66) whose guide diameter (68) is dimensioned larger than the diameter of the valve seat (80), so that in the closing direction the valve member (62) effective pressure level arises.

9. Kraftstoffϊnjektor (10) according to claim 1, characterized in that the valve seat (80) on a valve piece (32) is designed, which limits the control chamber (36) and a pressure chamber (34) in the injector body (16) against a low pressure ver - closes.