KR101796911B1 - Switchover valve comprising a valve body and a valve needle at least temporarily acting on the valve body in an opening direction - Google Patents

Abstract

A valve needle (20) comprising a valve body (26) and a valve needle (20) at least temporarily acting on the valve body, the movement of the valve needle being restricted by a stopper in at least one direction, A stopper 34 is formed in the recessed recess 24 in the valve body 26 and the valve body 20 is pushed against the end portion 32 of the valve needle 20, Lt; / RTI >

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a valve body including a valve body and a valve needle operable at least temporarily in the valve body,

The present invention relates to a switching valve according to the preamble of claim 1.

For example, a switching valve used as a flow control valve upstream of a high pressure pump for an automotive internal combustion engine is known in the market. Such a changeover valve often includes a valve needle that can act on a generally plate valve body.

It is also known to restrict the stroke of the valve needle in the switching valve at least in the axial direction by a so-called needle collar. The needle collar is rigidly coupled to the valve needle or is fabricated integrally with the valve needle. By the needle collar, the mass transferred is large, which must be taken into account particularly during the rapid conversion process.

In addition, in the injection valve, the motion of the "armature-needle-combination" formed by the valve needle and the armature in one axial direction is limited by the armature stopper of the electromagnet at the extremity and by the stopper on the sealing sheet of the injection valve in the other axial direction Are known.

An object of the present invention is to restrict the movement of the valve needle of the switching valve at the first stopper without the action of the needle collar.

The above problem is solved by the switching valve according to claim 1. Preferred embodiments are set forth in the dependent claims. Important features of the present invention are set forth in the following description and drawings, wherein the features are singly and in any combination are important to the present invention, unless clearly indicated.

The present invention has the advantage that the motion of the valve needle of the switching valve can be limited at the first stopper without the action of the needle collar and that a relatively large axial force can be transmitted to the valve needle or stopper with sufficient durability. The diameter of the valve needle can be reduced and the diameter jump can be omitted. In addition, the moving mass of the switching valve is reduced, the switching speed is increased, the operating noise can be reduced, and the cost can be reduced.

The present invention exploits the fact that the end portion of the valve needle collides against the valve body upon actuation of the diverter valve, and the valve body can hit the housing portion ("stop") of the diverter valve, for example. Thus, a first prerequisite is provided in which the axial movement of the valve needle is limited without the cooperation of the needle collar. The present invention also assumes that relatively large dynamic forces can act on the valve needle and the valve body, especially in the case of a rapidly switched valve. In order to prevent deformation of the valve needle and / or deformation of the valve body which is undesirable for the operation of the diverter valve, the valve body has a concave recess in accordance with the present invention in which the end portion of the valve needle hits . As a result, the possible "embedding" of the end portion into the valve body, at least during the operation of the switching valve, can be at least reduced since a possible deformation of the valve needle or valve body is structurally expected ("wear retention"). The present invention prevents the valve stroke and / or the magnetic force (operation stroke, air gap) from changing in an improper manner, so that an insufficient function of the switch valve can be given.

Complementarily, the recess is implemented rotationally symmetrically about the longitudinal axis, and as the depth of the recess increases, the radius of the recess monotonously decreases. For this reason, the valve body embodied in accordance with the present invention can always cause an optimal stop regardless of the possible rotation about the longitudinal axis of the switching valve. In addition, the recess is formed in accordance with the invention so that the valve body can be self-centered at least over a plurality of operating cycles of the switching valve with respect to the axis of the valve needle. This results in a particularly accurate conversion of the switching valve, at no additional cost.

In particular, the recess has a substantially round ceiling shape. Therefore, there is given a recess shape which is particularly suitable for the present invention, which can be manufactured simply and inexpensively.

The durability of the switching valve is further improved if the shape of the recess at the first stopper and the shape of the end portion of the valve needle are at least partially substantially complementary. As a result, the contact surface between the valve needle and the valve body can be optimized and the axial pressure appearing at the stopper can be limited. Preferably, a shape is also realized in which a sufficiently large contact surface can always be formed even in the radially slightly displaced valve body position.

In the application of the switching valve, the switching valve is a flow control valve of the high-pressure fuel pump. Flow control valves for fuel pumps in automobiles require very precise conversions to accurately measure the required amount of fuel, respectively. The switching speed of the switching valve can be increased while maintaining sufficient durability by the mass of the reduced valve needle in accordance with the present invention.

According to the present invention, the movement of the valve needle of the switching valve is restricted in the first stopper without the action of the needle collar.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view of a fuel system of an internal combustion engine;
2 is a cross-sectional view of the flow control valve of the fuel system of FIG.
Fig. 3 is an enlarged view of part III of the flow control valve of Fig. 2; Fig.
Figure 4 is a view similar to Figure 3;
Fig. 5 is a force diagram at the first stopper of the flow control valve of Figs. 2 to 4. Fig.
Figure 6 is a schematic diagram illustrating the axial movement of the piston of the high pressure pump of the fuel system of Figure 1;

Members and sizes of the same function in all the drawings are denoted by the same reference numerals in different embodiments.

1 schematically shows a fuel system 1 of an internal combustion engine. A switching valve 10 which is operable by the pre-delivery pump 5, via the low-pressure line 7 and by the electromagnet 15, from the fuel tank 9, through the intake line 4, (Piston) high pressure pump 3 (which is not described here) through the valve 10. At the downstream side, the high-pressure pump 3 is connected to the high-pressure accumulator 13 (common rail) through the high-pressure line 11. Other members, such as the discharge valves of the high-pressure pump 3, are not shown in FIG. The switching valve 10 or the flow control valve 10 may be formed as a unit having the high-pressure pump 3. For example, the flow control valve 10 may be an inlet valve of the high-pressure pump 3.

In addition, the flow control valve 10 may include an actuator other than the electromagnet 15, such as a piezo actuator or a hydraulic actuator.

In operation of the fuel system 1, the pre-delivery pump 5 delivers the fuel from the fuel tank 9 into the low-pressure line 7. The flow control valve 10 determines the amount of fuel supplied to the delivery chamber of the high-pressure pump 3.

Fig. 2 shows the flow control valve 10 of Fig. 1 in a sectional view. The flow control valve 10 is implemented rotationally symmetrical with respect to the longitudinal axis 12. The flow control valve includes a number of different types of housing sections 14 in which the members of the flow control valve 10 are disposed. 2, an armature 16 is disposed, which includes an axial armature hole 18 and is axially engaged with the valve needle 20. The armature 16, Here, the armature 16 is firmly connected to the valve needle 20. An armature spring 22 is disposed between the armature 16 and the housing section 14 at the top of the armature 16 in the figure. The armature 16 is a part of the electromagnet 15 which is not shown fully in Fig. A ring-shaped armature gap 19 is formed between the armature 16 and a pole core 17 arranged at the upper part in the drawing.

The armature 16 and the valve needle 20 associated with the armature 16 are radially guided in the flow control valve 10 by two guide sections. The first guide section 28 is formed as an axial section of the circumferential surface of the armature 16. The second guide section 30 is formed as the circumferential surface of the valve needle 20 which is in contact with the housing section 14 in the lower part of Fig. An opening 31 is arranged on the right side of the guide section 30 in the figure. The low pressure line 7 is connected to the radial opening 33 in the left region of the flow control valve 10 in the figure.

The end portion 32 of the valve needle 20 is configured such that the first stopper 24 formed by the limiting surface of the recess 24 in the rounded ceiling recess 24 of the valve body 26, (34) as viewed in the drawing. The shape of the end portion 32 and the recess 24 is at least partially embodied in a generally complementary manner. This provides a sufficiently large contact surface between the end portion 32 and the recess 24 so that the compressive stress generated in the end portion 32 or the recess 24 is kept relatively small. The recesses 24 are implemented rotationally symmetrical with respect to the longitudinal axis 12.

The valve body 26 strikes the dormant portion 36 of the housing member 38 in the forcibly opened position shown. The valve spring 40 embodied as a compression spring is disposed between the bottom of the housing member 38 and the valve body 26 and acts on the valve body 26 upwardly in the direction of the sealing sheet 42 do. Here, a ring-shaped gap 44 is formed between the sealing sheet 42 and the valve body 26, and fuel can flow into the delivery chamber of the fuel pump during operation through the gap.

2, electric current is not supplied to the electromagnet 15, and the armature 16, the valve needle 20 and the valve body 26 are disposed at the lowest position in the drawing by the force of the armature spring 22 . The end portion 32 rests on the concave side of the recess 24. The flow control valve 10 is opened and the high pressure pump 3 disposed downstream of the flow control valve 10 is in the suction stage.

In the following countercurrent step, the high-pressure pump 3 is not delivered by the forced-open flow control valve 10 and no current is supplied to the electromagnet 15. The flow control valve 10 is kept open by the armature spring 22.

At the start of the subsequent delivery stage of the high-pressure pump 3, electric current is supplied to the electromagnet 15, and the armature 16 is attracted by the extreme center 17. The valve needle 20 is lifted from the valve body 26 and in particular at least the valve spring 40 is supported by the hydraulic fluid force in the flow control valve 10, Lt; / RTI > The ring-shaped gap 44 can disappear and the flow control valve 10 can be closed. Now, the fuel is delivered into the high pressure accumulator 13 ("rail").

After the end of the dispensing step, the current supply to the electromagnet 15 is cut off and then the armature spring 22 urges the armature 16 together with the valve needle 20 downward in the figure. The end portion 32 of the valve needle 20 hits the valve body 26. The valve body 26 is then lifted from the sealing sheet 42 and is urged against the dormant portion 36 - again supported by the fluid force. When the end portion 32 hits the recess 24 of the valve body 26, a relatively large force is generated. Here, the shape of the round ceiling recess 24, and the shape of the end portion 32 at least partially complementary thereto, maintains a relatively small local compressive stress applied during impact.

The rounded ceiling recess 24 also has the characteristic that the (axial) depth of the recess 24 with a decreasing radius monotonously increases. For this reason, the valve body 26 can be self-centered as described below with respect to the valve needle 20 or the longitudinal axis 12.

Fig. 4 shows a view similar to Fig. 3 of a slightly modified embodiment of the flow control valve 10. Fig. The members shown can be distinguished by reference numerals.

5 shows a force diagram when the end portion 32 of the valve needle 20 hits against the recess 24 of the valve body 26. Fig. The normal force 50 with the direction of the local plane normal at the stopper 34 is divided into an axial component 52 and a radial component 54. The radial component 54 is directed in a direction that allows centering between the valve needle 20 and the valve body 26. The farther away the valve needle 20 is from the center of the recess 24, the larger the radial component 54 is. Alternatively, if the axes of the valve needle 20 and the recess 24 are the same, the two elements are already centered maximally and the radial component 54 is zero (not shown).

The shape of the recesses 24 of FIGS. 2-5 may be implemented differently. In particular, the axial depth of the recess 24 may be less than that shown in FIG.

Fig. 6 shows a coordinate system showing the axial movement of the piston of the high-pressure pump 3 embodied as a piston pump. The abscissa represents time and the ordinate represents the stroke 60 of the piston (not shown in Fig. 6). Horizontal dashed line 62 represents the top dead center of the piston motion. The bottom dead center of the piston motion corresponds to a stroke 60 of zero.

Arrow 64 represents the time range of the suction step, arrow 66 represents the time range of the backflow step, and arrow 68 represents the time range of the delivery step of the high pressure pump 3. In total, the three displayed phases represent the period of the operating movement of the high-pressure pump 3.

The suction phase is defined between the top dead center and the subsequent bottom dead center. Subsequent reflux steps start at the bottom dead center and end at time t1, for example, before reaching the subsequent top dead center. Subsequent delivering steps begin at time point t1 and end at a subsequent top point. The time point t1 depends on the control of the electromagnet 15 of the flow control valve 10. [

3: High-pressure fuel pump 10: Switch valve
12: longitudinal axis 20: valve needle
24: recess 26: valve body
32: end portion 34: stopper

Claims (2)

And a valve needle (20) at least temporarily acting on the valve body, the movement of the valve needle being restricted by a stopper in at least one direction, ),
A first stopper (34) for the valve needle (20) is formed on the recessed recess (24) in the valve body (26)
The recess 24 is embodied in rotational symmetry with respect to the longitudinal axis 12 and the radius of the recess 24 monotonically decreases as the depth of the recess 24 increases,
The recess 24 has the shape of a round ceiling,
The shape of the recess 24 in the first stopper 34 and the shape of the end of the valve needle 20 can be adjusted by making a surface contact to maximize the contact area between the valve needle 20 and the valve body 26. [ The shape of the portion 32 is at least partially complementary,
An armature 16 is fixedly connected to the valve needle 20 and an armature spring 22 is disposed between the armature 16 and the housing section 14 of the switching valve 10, Is disposed apart from the armature (16)
When the electromagnet 15 is energized, the armature 16 is pulled by the extremity 17 so that the valve needle 20 is spaced from the valve body 26,
When the supply of current to the electromagnet 15 is interrupted, the armature spring 22 presses the armature 16 against the valve body 26 such that the end portion 32 of the valve needle 20 is in contact with the valve And bumps against the recess (24) of the body (26). The switching valve according to claim 1, wherein the switching valve is a flow control valve (10) of the high-pressure fuel pump (3).

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