WO2010009925A1

WO2010009925A1 - Armature pin for solenoid valve

Info

Publication number: WO2010009925A1
Application number: PCT/EP2009/056403
Authority: WO
Inventors: Norbert Schoefbaenker; Karl Kaeferboeck; Michael Petschnik; Dieter Deutsch
Original assignee: Robert Bosch Gmbh
Priority date: 2008-07-22
Filing date: 2009-05-27
Publication date: 2010-01-28
Also published as: DE102008040589A1

Abstract

The invention relates to a solenoid valve (12), especially for controlling an injection valve of a fuel injector, comprising an electromagnet (16), an armature assembly (24), and a closing element (44), which moves with said armature assembly (24) and which is acted upon in the closing direction by a closing spring (27) and interacts with a valve seat (46). The armature assembly (24) has an at least multipart design and comprises a first armature part (26), which can be moved relative to a second armature part (28) against the action of an armature spring (38) in the closed position of the closing element (44), wherein a hydraulic damping device is associated with the armature assembly (24). The damping device is provided in the area of a contact point (30) between the electromagnet (16) of the armature assembly (24) and an armature part (26, 28).

Description

description

title

Anchor bolt for solenoid valve

State of the art

DE 196 50 865 Al describes a solenoid valve for controlling the fuel pressure in a control chamber of an injection valve, such as a common rail injection system. About the fuel pressure in the control chamber, a stroke movement of a valve piston is controlled by an injection opening of the injection valve is opened or closed. The solenoid valve comprises an electromagnet, a movable armature and a valve member moved with the armature and acted upon by a valve closing spring in the closing direction, which cooperates with the valve set of the solenoid valve and thus controls the fuel drain from the control chamber.

It is known a common rail injector with a two-piece anchor, which is attracted by a magnet. The armature exerts the closing force on a valve ball in the currentless case. When the electromagnet is energized, the armature moves upwards around the armature stroke, the closing force on the valve ball becomes zero and an outflow valve opens. An armature guide, which is screwed tightly in the injector body of the fuel injector, takes the armature bolt in the axial direction movable. On the anchor bolt, the anchor plate is guided, which in turn is attracted by the electromagnet.

The anchor plate has a defined overstroke on the Ankerfύhrung, which takes the kinetic energy of the movement of the armature after switching off the electromagnet from the system. When the valve ball hits its seat, the anchor bolt is stopped in its movement. The anchor plate can still fly by one overstroke (ballistic operating phase) before it hits the overstroke stop. Thus, only a portion of the kinetic energy from the movement of the anchor bolt in the valve seat must be reduced. Part of the kinetic energy of the anchor plate is dissipated in the injector body. Injection quantity deviations in the ballistic operating phase may be different from fuel injector to fuel injector and originate from the region of the solenoid valve. Fuel injectors, the solenoid valve are provided with a two-piece anchor can have a different bounce behavior on a guide sleeve. A "start-up bounce", which occurs especially at high pressures, may be different in severity and have an impact on the injection quantity in the ballistic phase of the fuel injector. In currently used anchor bolts of solenoid valves, only angular geometries of> 90 ° are made for manufacturing reasons at the top of the anchor bolt in the shoulder. The shoulder surface of the anchor bolt represents the contact surface of the anchor plate, which is arranged relatively movable to the anchor bolt, with respect to the end face of the anchor bolt.

Disclosure of the invention

According to the invention, a solenoid valve is provided, in particular for controlling an injection valve of a fuel injector, with an electromagnet, an armature assembly and a moving with the armature assembly, acted upon by a closing spring in the closing direction closing element, which cooperates with a valve seat, wherein the armature assembly is formed at least in several parts and a comprises first anchor member which is displaceable relative to a second anchor member against the action of an armature spring in the closed position of the closing element, wherein the armature assembly is associated with a hydraulic damping device.

At the solenoid valve high demands of the switching accuracy are to be made. In particular, bouncing of the valve member and the effects of vibration are disadvantageously noticeable. A bounce arises in particular when a relatively large mass is accelerated and then abruptly braked suddenly and when anchor bolts strike with anchor plate and valve member as a mass on the valve seat. However, since a substantial part of the armature mass and that the armature plate is slidably mounted on the anchor bolt, the armature plate can continue to move against the force of the armature spring after placing the closing element on the valve seat, so that on the one hand, the actual braked mass and the elastic deformation of the valve seat Energy storage, which leads to the adverse rebounding of the valve member, is now less. The trailing armature plate also generates an increasing force by compressing the armature spring, which additionally holds the valve member stably on its seat and counteracts the bouncing. However, this hunting can disadvantageously create significant swinging of the armature plate against the armature spring, so that the position of the armature plate is undefined in an immediately thereafter required operation of the valve member and switching of the solenoid valve is not sufficiently fast and with reproducible constant switching time. Due to the additional volume in the damping chamber of the armature assembly, the anchor bolt is hydraulically damped. In addition, by the decoupling of the anchor bolt from the anchor plate over the life of the injector, the solenoid valve in the small amount range is much less sensitive to changes in Magnetventilhubänderungen.

It is advantageous if the first anchor part is embodied as an anchor bolt, which is slidably guided in the second anchor part designed as an anchor plate, wherein the damping device comprises at least one damping chamber, in particular in the region of the flat side of the anchor plate or a shoulder surface of the anchor bolt a stop surface is provided between the first anchor part and the second anchor part.

An additional possibility is, according to a development of the invention, that at least one damping chamber is embedded in the region of the end face of the anchor plate. As a result, the damping chamber can be accommodated inexpensively in the armature assembly in a simple manner.

Further, it is advantageous that the damping chamber is received in the guide sleeve in the region of the opposite contact surfaces of the anchor bolt and the anchor plate and / or a guide sleeve and / or the electromagnet and the anchor plate and a further damping chamber in which the anchor bolt is slidably received.

It is advantageous for this purpose that the one damping chamber is formed as a recess which is embedded in the anchor plate and whose radial outer boundary has a diameter which is greater than an outer diameter of a part of the anchor bolt, which bears against a surface of the recess.

According to a preferred embodiment of the solution according to the invention, it is finally provided that the damping chamber consists of a first damping subspace provided in the armature plate and a second damping subspace provided in the electromagnet and / or the guide sleeve, the damping subspaces facing one another and then in flow communication when the anchor bolt is moved away from the surface of the recess. - A -

Of particular importance for the present invention that the anchor bolt consists of at least two coaxially connected anchor bolt sections with different sized outer diameters, between the two anchor bolt sections, the shoulder surface is provided, which rests with its corner edge region on the surface of the recess of the damping chamber.

In connection with the design and arrangement according to the invention, it is advantageous that the corner edge region is formed by the transition from a lateral surface to the Schulterfiäche of the anchor bolt, in particular to its central anchor bolt portion and linearly rests on the surface of the recess of the damping chamber. Due to the line contact between the anchor bolt and the anchor plate this can solve better when hitting the anchor plate to the guide sleeve and continue to swing against the solenoid spring force. As a result of this larger armature stroke, the injection quantity in the fuel injector according to the invention is also increased in the pre-injection quantity range for a short activation time. Due to the decoupling of the anchor bolt and the anchor plate of the anchor bolt hits again on the anchor plate, if this has swung out after hitting the guide sleeve. Before re-encountering the anchor bolt on the anchor plate of this is hydraulically damped by the additional volume in the damping chamber, as accumulates additional volume in the area of the conical surface. Due to the decoupling of the anchor bolt from the anchor plate, the valve also becomes much less susceptible to changes in the solenoid valve stroke over the runtime of the injector in the small-volume range.

It is furthermore advantageous that the guide sleeve receiving the anchor bolt has the end face pointing in the direction of the second armature part, which bears constantly against the abutment surface of the armature plate and the radial outer boundary of the damping subspace in the guide sleeve outside the radial outer boundary of the armature plate provided damping subspace is located.

Moreover, it is advantageous that adjoins the stop surface of the anchor plate, which extends radially and is flat, a slider with a centrally disposed guide bore, in which the anchor bolt is slidably received.

With reference to the drawings, the invention will be described in more detail below.

It shows: Figure 1 is a partial section through an electrically controlled solenoid valve;

Figure 2 is a sectional view of an anchor bolt with anchor plate;

Figure 3 is a partial sectional view of Figure 2, as engraved encircling a right part of an anchor bolt with anchor plate in an enlarged view with the damping chamber according to the invention in the corner edge region of the anchor bolt.

Figure 4 shows the course of the valve lift of solenoid valves with an anchor bolt and a relative to the anchor bolt relatively adjustable armature plate and a damping chamber in the corner edge region of the anchor bolt;

5 shows the course of the injection quantity of solenoid valves with an anchor bolt and a damping chamber:

Figure 6 shows the course of the injection quantity of solenoid valves with an anchor bolt and a damping chamber, in particular caused by the anchor plate according to the invention improvement in the injection quantity at smaller driving times.

embodiments

The illustration according to FIG. 1 shows an electrically controlled solenoid valve 12 for a fuel injector 10, which is shown only partially, and which is described in the introduction

State of the art is known. Such a solenoid valve 12 is for use in a

Fuel injection system determined, which is equipped with a high-pressure fuel storage, which is supplied by a high-pressure pump continuously high-pressure fuel and through which this fuel is supplied under injection pressure via individual electrically controlled Mag- netventile the internal combustion engine.

An injector body 14 is actuated by means of the solenoid valve 12. The solenoid valve 12 is received in the upper region of the injector body 14 of the Kraftstoffϊnjektors not shown in the drawing 10. The fuel injector 10 is embodied substantially symmetrically with respect to an axis 18. The magnetic valve 12 according to FIG. 1 comprises a magnet group with a magnetic core 16 and a magnet coil 20 embedded therein. The magnet core 16 encloses a guide sleeve 22, at the lower end side of which a stop surface 32 is embodied. The magnetic core 16, in this embedded magnetic coil 20 and the guide sleeve 22 are also arranged symmetrically to the valve axis 18. The solenoid valve 12 also includes an armature assembly 24, which - as shown in Figure 1 - is acted upon by a closing spring 27 in the closing direction of the solenoid valve 12. The armature assembly 24 is also symmetrical to the valve axis 18 and a plurality of parts, in particular in two parts, and comprises a first anchor part, which is designed here as an anchor bolt 26 and a second anchor member which is slidably mounted here as anchor plate 28 on the anchor bolt 26. The magnetic core 16 with embedded magnetic coil 20 facing planar side of the armature plate 28 is designated by the reference numeral 30. The anchor bolt 26 of the armature assembly 24 is slidably guided in a guide bore 29 above a valve seat 46 of the solenoid valve 12. The stop surface 30 of the anchor plate 28 extends radially and is flat. Following the plane stop surface 30, the anchor plate 28 has a cylindrically shaped slider 31 with a centrally arranged guide bore 33, in which the anchor bolt 26 is likewise slidably received.

From the representation of Figure 1 shows that the anchor plate 28 which is slidably guided on the anchor bolt 26 of the armature assembly 24, is acted upon by an armature spring 38, which is supported on the inside of a valve clamping nut 36, which also forms an anchor bolt guide.

From the illustration according to FIG. 1, it is also apparent that the magnetic valve 12 comprises a ball-shaped closing element 44, which closes the valve opening in a valve seat 46, which lies in the valve axis 18, and in that the valve seat 46 is designed as a conical seat and in the in FIG Figure 1 shown state by the here spherically shaped closing element 44, formed as a nip, is included. A bore 45 below the valve seat 46 is filled with a reduced amount of fuel which is released by the closure member 44.

Figures 2 and 3 show that the anchor bolt 26 at least two coaxially connected anchor bolt portions 40, 42 with different sized outer diameters, wherein between the two anchor bolt portions 40, 42 a Schulterfiäche 48 is provided and formed so that it with its Eckkantenbereich 50th is linearly seated on a surface 52 of a damping device. The corner edge region 50 is defined by the Transition from a lateral surface 54 of the one anchor bolt portion 40 to the shoulder surface 48 of the anchor bolt 26, in particular the central anchor bolt portion 40 is formed, to which the anchor bolt portion 42 coaxially connects.

In Fig. 3, the damping device is illustrated and shown in larger scale. This includes the damping chamber, in particular a provided in the first anchor member 26 damping subspace 56 and a second provided in the guide sleeve 22 damping subspace 58, which are opposite, adjacent to each other and in flow communication, if the shoulder surface 48 with its corner edge 50 not on the surface 52 of the damping subspace 56 is seated.

The damping chamber, in particular the damping subspace 56, is embedded at least in the plane side 30 of the anchor plate 28. With the additional volume accommodated in the damping chamber or in the damping sub-spaces 56 and 58, this is available as a damping means. The additional volume accumulates during the injection process in the damping chamber or in the damping subspaces 56 and 58 before the closing element 44 is seated on the valve seat 46.

The damping chamber, in particular the damping subspace 56, is formed as a frusto-conical recess with the surface 52, which is embedded in the first anchor member 26 and whose radial outer boundary has a diameter D which is greater than the outer diameter d of the one anchor bolt portion 40 of Anchor bolt 26 which rests with its corner edge 50 with a radius R of FIG. 3 at the transition from lateral surface 54 to the shoulder surface 48 linearly on the surface 52 of the recess. The outer diameter D of the radial boundary of the conical surface 52 is selected so that the active abutment surface 32 on the guide sleeve 22 in the magnet 16 is not reduced. In the known injectors, the anchor bolt with its shoulder surface is full on the anchor plate. The diameter D of the radial boundary of the conically extending surface 52 is further made so large that the anchor bolt 26 with the diameter d always rests on the conical surface within the radial outer boundary. A cone angle α of the conical recess is in the range between 140 ° and 175 °.

The anchor plate 28 also has, subsequent to the tapered conical surface 52 of the damping device on a chamfer 53, which by machining the edge on the guide bore 29 in the anchor plate 28 z. B. is formed by turning, milling or planing and the an angle β which is between 25 ° and 35 °. Thus, the anchor bolt 26 can be easily inserted into the bore 29.

The closing element 44 is coupled to the two-part armature, in the form of the anchor bolt 26 and the armature plate 28, which is adjustable relative to the armature bolt 26 and which cooperates with the electromagnet 16 of the solenoid valve 12.

As a result, the anchor plate 28 is brought with its flat side 30 against the lower in the direction of the flat side 30 facing stop surface 32 of the guide sleeve 22 in the magnet 16 for Ange- ge.

The anchor bolt 26, the anchor plate 28 and connected to the anchor bolt 26 closing member 44 are constantly acted upon by the closing spring 27 fixed to the housing fixed in the closing direction, so that the closing element 44 is normally in the closed position on the valve seat 46. Upon energization of the electromagnet 16, the armature plate 28 is attracted by the electromagnet while the bore 45 is opened below the valve seat 46 to a relief space, not shown here.

The illustration according to FIG. 4 shows magnetic valve lift characteristics plotted over the actuation duration of a solenoid valve according to the prior art and of the solenoid valve 12 with the armature assembly 24 proposed according to the invention. As shown, lift characteristics 62, 64 of solenoid valves are contrasted with one another.

The curve designated by the reference numeral 62 in FIG. 4 refers to a valve according to the prior art and the curve designated 64 indicates the course of the solenoid valve 12 according to the invention with the damping chambers 56 and 58 provided in the armature assembly 24 are formed without reducing the active stop surface 30 on the guide sleeve 22. If the solenoid valve 12 is energized, the anchor bolt 26 is lifted with the closing element 44 from the valve seat 46 and then brought to the stop.

With the additionally formed volume in the damping chambers 56, 58, the desired damping of the anchor bolt 26 is achieved shortly before striking the anchor plate 28.

In a Einschaltpreller, as shown in Figure 4 by the reference numeral 68, there is a considerable spread with respect to the amplitudes of the attacks of the anchor plate 28th In contrast, with the proposed solution according to the invention when using the armature assembly 24 according to Figure 3, in particular with the measures provided for in the armature plate 28 and the anchor bolt 26 damping chambers 56, 58, to achieve a significantly reduced spread.

Due to the line contact between the anchor bolt 26 and anchor plate 28 of the impulse when hitting the anchor plate 28 is transmitted to the guide sleeve 22 directly to the anchor bolt 26 so that it resonates longer and thereby in the pre-injection range at smaller driving times a much larger injection quantity is achieved, as from the Graph of FIG. 6 shows. This shows a distance 60 between two curves 76 (prior art) and 78 (improvement over the prior art) in an amount between 0 and 5 mnvVHub. This is further indicated by the curve portion 68, 72 in Fig. 4, which also illustrates the very large difference 66 between the two maximum excursions of the curves 62 and 64. Furthermore, this is also illustrated by the concave curve section 69 in FIG. 4 between the times of approximately 250 μs and 700 μs.

FIG. 5 shows the injection quantity mnvVHub and the characteristic gradient over the time axis μs. As can be seen from the illustration, the characteristic slope is compared by the curves 74 and 76 and by the curves 78, 80 of solenoid valves to each other. Reference numerals 76 and 80 - dashed curve - each shows an average, which is stored in the engine control unit. The curve denoted by 76 refers to the course of a solenoid valve according to the prior art and the curve designated by reference numeral 80 refers to the characteristic curve of the solenoid valve 12 according to the invention.

The characteristic slope, derived from the upper curve, shows an improved characteristic curve, especially in the small volume range up to approx. 360 μs, ie also that the characteristic gradient is significantly reduced up to injection quantities of approx. 20 mm ³ / stroke. It is essential here that no excessive parallel deviation of the actual curve shape from the mean value characteristic stored in the control unit occurs. The improved curve is indicated by the reference numeral 80.

Claims

claims

1. Solenoid valve (12), in particular for controlling an injection valve of a fuel injector, with an electromagnet (16), an armature assembly (24) and with the armature assembly (24) moved by a closing spring (27) acted upon in the closing direction closing element ( 44), which cooperates with a valve seat (46), wherein the armature assembly (24) is formed at least in several parts and a first anchor part (26) summarizes the relative to a second anchor member (28) against the action of an armature spring (38). in the closed position of the closing element (44) is displaceable, wherein the armature assembly

(24) is associated with a hydraulic damping device, characterized in that the damping device in the region of a contact point (30) between the electromagnet (16) of the armature assembly (24) and an anchor member (26, 28) is provided.

2. Solenoid valve according to claim 1, characterized in that the first anchor part (26) is designed as an anchor bolt which is slidably guided in the armature plate formed as the second anchor member (28), wherein the damping device comprises at least one damping chamber (56, 58), in the region of the flat side (30) of the anchor plate or a shoulder surface (48) of the anchor bolt (26), in particular a stop surface (32), see between the first anchor member (26) and the second anchor member (28) is provided.

3. Solenoid valve according to claim 1 or 2, characterized in that at least one damping chamber (56, 58) in the region of the end face (30) of the anchor plate (28) is embedded.

4. Solenoid valve according to one of the preceding claims, characterized in that the damping chamber (56) in the region of the opposite contact surfaces (30) of the anchor bolt (26) and the anchor plate (28) and / or a guide sleeve (22) and / or Electromagnet (16) and the armature plate (28) and a further damping chamber (58) in the guide sleeve (22) is received, in which the anchor bolt (26) is slidably received.

5. Solenoid valve according to one of the preceding claims, characterized in that the one damping chamber (56) is formed as a recess which is embedded in the armature plate (28) and whose radial outer boundary has a diameter (D) which is greater than a Outer diameter (d) of a part (40) of the anchor bolt (26), which bears against a surface (52) of the recess.

6. Solenoid valve according to one of the preceding claims, characterized in that the damping chamber from a first in the anchor plate (28) provided damping subspace (56) and a second in the electromagnet (16) and / or the Führungshül- se (22) provided damping subspace (58), wherein the damping subspaces

(56, 58) are opposed and then in flow communication when the anchor bolt (26) is moved away from the surface (52) of the recess.

7. Solenoid valve according to one of the preceding claims, characterized in that the anchor bolt (26) consists of at least two coaxially interconnected anchor bolt portions (40, 42) with different sized outer diameters, wherein between the two anchor bolt portions, the shoulder surface (48) is provided with its corner edge region (50) on the surface (52) of the recess of the damping chamber (56) is seated.

8. Solenoid valve according to one of the preceding claims, characterized in that the corner edge region (50) by the transition from a lateral surface (54) to the shoulder surface (48) of the anchor bolt (26), in particular to its central anchor bolt portion (40) is formed and is linearly seated on the surface (52) of the depression of the damping chamber (56).

9. Solenoid valve according to one of the preceding claims, characterized in that the armature pin (26) receiving the guide sleeve (22) in the direction of the second armature part (28) facing end face which constantly against the abutment surface (30) of the armature plate (28). is applied and the radial outer boundary of the damping subspace

(58) in the guide sleeve (22) outside the radial outer boundary of the anchor plate (28) provided in the damping subspace (56).

10. Solenoid valve according to one of the preceding claims, characterized in that the stop surface (30) of the armature plate (28), which extends radially and is flat, a slider (31) with a centrally arranged guide bore (29) connects, in the anchor bolt (26) is slidably received.