WO2008113628A1

WO2008113628A1 - Pressure-compensated control valve

Info

Publication number: WO2008113628A1
Application number: PCT/EP2008/050935
Authority: WO
Inventors: Holger Rapp; Wolfgang Stoecklein; Christoph Radsak; Nadja Eisenmenger
Original assignee: Robert Bosch Gmbh
Priority date: 2007-03-20
Filing date: 2008-01-28
Publication date: 2008-09-25
Also published as: DE102007013245A1

Abstract

The invention relates to a control valve (10) for a fuel injector, having a valve element (16) that is guided on a valve guide (22). The valve element (16) opens or closes a seat (18). A radial recess (48) is configured in the valve element (16), the system pressure p sys being applied to said recess. In this manner the seat region is deformed such that the surface pressure in the valve seat is concentrated on the inside edge thereof, thus ensuring leak tightness despite of any wear that may occur.

Description

description

title

Pressure compensated switching valve

State of the art

In pressure compensated switching valves, the pressurized medium is usually enclosed in a closed pressure chamber in an annular pressure chamber. This chamber is bounded on one side by a guide and on the other side by a sealing seat, wherein guide and sealing seat have exactly the same diameter d. As a result, there is no force acting in the opening or closing direction on the valve element, which may be of a needle-shaped or sleeve-shaped design.

With progressive operation of the switching valve, there is an alignment between the sealing surface of the valve piece and the needle-shaped or sleeve-shaped valve element. Since the adjustment takes place, starting from the original diameter d, only to one side, a change in the effective seat diameter and thus the generation of an opening force acting on the valve element the result. The pressure balance of the switching valve is disturbed and its dynamic behavior changes up to static leakage.

With pressure-balanced switching valves, usually only a small mechanical force is available to keep the valve tight. As wear increases, the components on the valve seat become more and more similar, and a contact width between the components increases. As long as the sealing diameter at the valve seat still corresponds to the guide diameter, the valve function is maintained. However, if the sealing diameter is removed away from the guide diameter, an additional pressure stage is created on the valve which generates a force acting in the opening direction. This can lead to the valve unintentionally opening as the wear increases (seat alignment). In particular, in the case of switching valves for high-pressure applications, the deformation of the components in the closed state by the pressure load, ie the system pressure prevailing in the component, plays a major role. This deformation can massively increase the effect of the seat match and thus lead to premature failure of the valve by statically cal leak. From Figure 1, the mechanism shows that leads to progressive wear and deformation due to a pressure effect to leakage of the switching valve.

From DE 100 08 554 Al a fuel injection valve for internal combustion engines is known which has an increased density. The fuel injection valve comprises at least two valve body parts, which abut each other on a contact surface and are clamped by a clamping device against each other perpendicular to the contact surface. In both valve body parts, an inlet for fuel is formed, which passes through the contact surfaces and in which a high fuel pressure prevails. In the inlet channel, at least one radial extension is formed near the contact surface of the relevant valve body part, so that this radial expansion experiences an expansion in the axial direction of the inlet channel due to the fuel pressure in the inlet channel. As a result, the region of the contact surface surrounding the passage of the inlet channel is pressed against the contact surface of the adjoining valve body part, so that the contact pressure of the contact surfaces increases. Thus, the passage of the inlet channel is better sealed due to the higher sealing effect, or it can be reduced according to the force of the clamping device without affecting the pressure required for the seal.

Disclosure of the invention

According to the invention, a pressure compensated switching valve is proposed in which a compensation or reduction of the prevailing due to the effect of the system pressure deformation is achieved. Due to the compensation or reduction of the deformation of the switching valve by the pressure prevailing in this high pressure, the sealing diameter of the inventively proposed switching valve is always despite adjusting wear on the guide diameter. As a result, static leakage can be avoided and a safe valve function can be ensured despite adjusting mechanical wear and associated seat alignment.

The inventively proposed geometry of the valve element, in particular in the region of its valve seat, refers to a seat contour, which deforms the seating area so that the surface pressure in the valve seat concentrates on the inner edge of the pressure increase, ie, loading the valve element with the system pressure. This compensates for the unwinding of the seat diameter to the outside. This in turn has the effect that no additional pressure stage is formed in the region of the valve seat, in particular on the valve element, on which an opening in the direction of opening of the valve element is formed. Mentes acting force would set, so that the inventively proposed switching valve remains permanently sealed.

The inventively proposed solution of the switching valve in particular in the region of the valve element in the valve seat is characterized in that on the high pressure side, ie the pressurized with system pressure side of the valve element, a radial extension, such as a compensation groove, preferably in a radius R _N in Guide portion of the valve element is attached to a valve guide. This radial extension, which is preferably made as a compensation groove in a radius R _N , is located in the vicinity of the valve seat at a distance A _N. The radial expansion deforms upon application of system pressure such that the valve seat line of the guide tilts.

By acting on the inside of the radial expansion formed in the valve element, preferably in the form of a compensation groove, the seat angle of the valve element is changed in the case of an applied system pressure p _{sys in} such a way that the valve element tilts to the inside edge. Thus, the sealing diameter moves along the inside of the sleeve-shaped valve element and seals on its guide diameter.

The shape of the radial enlargement, which is preferably made as a compensation groove, ensures that the maximum of the surface pressure in the radial extension in the valve element lies precisely at the point at which the seat edge is formed at a distance A _N. By applying the seat edge with maximum surface pressure and the hiking of the seat edge along the inner diameter, ie the guide diameter of the valve guide surrounding the valve element, it is achieved that the sealing diameter coincides with the guide diameter of the sleeve-shaped valve element on the valve guide. The known from the solutions according to the prior art Sitzangleich or rolling due to infiltration of the valve seat with fuel under high pressure can be effectively excluded by the measures taken. The measure taken, ie the attachment of a radial extension on the inside of the valve element, can, following the idea of the kinematic reversal, also be carried out on the valve guide.

Brief description of the drawings

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

It shows: FIG. 1 shows a pressure compensated switching valve,

FIG. 2 shows a seating area when subjected to system pressure when new,

FIG. 3 shows the seating area according to FIG. 2 in the worn state;

Figure 4 shows a valve element of the pressure balanced trained switching valve with radial expansion in the unpressurized state and

Figure 5 shows the valve element shown in Figure 4 in a pressureless state in the pressurized state.

embodiments

Figure 1 shows schematically a switching valve 10 which is symmetrical to the symmetry axis 12 is formed. The switching valve 10 is an outwardly opening switching valve 10, ie, a sleeve-shaped valve element 16 is accommodated on a valve guide 22. Between the inside of the sleeve-shaped outer valve element 16 and the valve guide 22, a high-pressure chamber 14 is formed, which is acted upon by a high pressure source, not shown in FIG. 1, with fuel under system pressure p _sys . The valve element 16, which is guided in a guide length 20 on the valve guide 22, closes or opens a seat 18, which is arranged at the bottom of the valve body 22 in the illustration according to FIG. The measures described below according to the invention can be carried out on any pressure balanced switching valve 10, the representation of the outwardly opening switching valve 10 according to claim 1 is purely exemplary to understand. Both the sleeve-shaped valve element 16 and the valve guide 22 are formed symmetrically to the symmetry axis 12. The switching valve 10 shown in FIG. 1 is one in which the valve seat 18 is located below the valve element 16 arranged on the outside. The valve element 16 is slidably guided in the guide length 20 on the valve guide 22. The guide diameter, ie, the inner diameter of the valve element 16 and the outer diameter of the valve guide 20 is denoted by reference numeral 64.

Figure 2 shows the representation of the seating area at a switching valve when new.

From the reproduced with severely exaggerated deformations Figure 2 shows that the high-pressure chamber 14 on pressurization with the system pressure p _sys on the one hand by a bottom surface 42 of the high-pressure chamber 14 and on the other hand by an inner side 40 of the valve element 16 is limited. The inner side 40 of the externally arranged valve element 16 has a seat edge 24, which forms the seat 18 with a complementarily formed edge, which is formed on the valve guide 22. From the illustration according to FIG. 2, it can be seen that, starting with the seat edge 24, the seat angle has been set to a seat adjustment 26. Within this identified by reference numeral 26 area, ie the seat alignment, are the contacting surfaces of the valve element 16 and valve guide 22 and its bottom 42 to each other. The arrows indicate the system pressure p _sys acting on the inside 40 or bottom 42 of the valve guide 22.

FIG. 3 shows the seating area of the switching valve according to the representation in FIG. 2 in the worn state after a relatively long operating time.

It can be seen from the illustration according to FIG. 3 that starting from the seat alignment 26 shown in FIG. the contacting sides of the valve element 16 and the valve guide 22 in the region of the seat 18, the seat edge 24 is exposed to a pressure infiltration 30. Thus, the seat diameter moves in the radial direction to the outside, forming a rolling surface 32. Seen in the radial direction on the outside, behind the rolling surface 32 is the point at which there is a maximum pressure 34. This seat line has moved further in the radial direction outward compared to the original seat edge 24. Due to the pressure infiltration 30 of the seat edge 24 on the underside of the sleeve-shaped outer valve element 16, an additional pressure stage is formed, which provides a force acting in the opening direction on the sleeve-shaped valve element 16 force which promotes unintentional opening of the valve element 16, whereby this switching valve after a long time Operating time due to the described effects and the occurred mechanical wear no longer reliably seals.

The illustration according to FIG 4 is an embodiment of the inventively proposed, pressure compensated trained switching valve, wherein in particular the externally arranged valve element is shown in the pressureless state.

As is apparent from FIG. 4, the sleeve-shaped, outer valve element 16, which-as shown in FIG. 1 -is guided on the lateral surface of the inner valve guide 22 along the guide length 20, has an inner side 40. In the sleeve-shaped valve element 16, the inner side 40 is formed in a guide diameter 64, which essentially corresponds to the outer diameter of the lateral surface of the valve guide 22. corresponds. On the inner side 40 of the valve element 16 is a radial extension 48. The radial extension 48 is procured in the representation of Figure 4 as Kompensationsnut and in the radius R _N , compare reference numeral 50, is formed. Taking into account the strength properties and taking into account the system pressure p _{sys present} in the radial extension 48, the groove can also be manufactured differently from the ideal shape as an annular groove in an angular diameter, for example as a rectangular groove, taking into account the resulting notch effect. The decisive factor is that a concentration of the self-adjusting surface pressure on the inside 40 of the valve element 16 is achieved by the geometry of the radial extension 48, which is formed in particular as a compensation groove with a rounded groove bottom. As shown in the illustration of Figure 4, located below the lower edge of the radial extension 48 at a distance A _N , reference numeral 46, the seat edge 24. From the seat edge 24 of the seat edge region 26 indicated in Figure 2 by reference numeral 26, within there is a contact between the underside of the valve element 16, formed in the seat angle, and the corresponding side of the valve guide 22 to form the seat 18.

As is further apparent from the illustration according to FIG. 4, the sleeve-shaped, external valve element can be moved in the direction of the double arrow 44. In a vertical upward movement, the sleeve-shaped, external valve element 16 opens the seat 18; in a method down the outer valve element 16 closes with its seat edge 24, the seat 18 between the valve guide 22 and the sleeve-shaped, outer valve element 16th

While in the representation according to FIG. 4 the sleeve-shaped, outer valve element 16 is shown in the depressurized state, this deforms when the system pressure p _sys is applied from the high-pressure space 14 between the valve element 16 and the valve guide 22 when the seat 18 is closed, as shown in FIG Figure 5 shown in more detail.

From the illustration according to FIG. 5, it can be seen that in the unpressurised state-indicated by the dashed lines, cf. reference numeral 52 -the radial extension 48 has its original undeformed appearance-as shown in FIG.

Since the radial extension 48 within the high-pressure chamber 14 between the valve guide 22 and the inner side 40 of the sleeve-shaped, outer valve element 16 system pressure p _{sys is} applied, deforms the radial extension 48, preferably formed as an annular Kompensationsnut, as shown in Figure 5. Im in shown by solid lines pressurized state 54 undergoes the radial extension 48 a widening 60, ie due to the pending on the boundary surface of the radial extension 48 system pressure wander the boundary edges of the radial extension 48 on the inside 40 of the sleeve-shaped, outer valve element 16 away from each other, the radial Extension 48 expands. Due to this circumstance, the lower boundary edge of the radial extension 48 moves downward in the vertical direction. As a result, the distance 46 A _N from this remote seat edge 24 moves on the inside 40 further down, that is, the seat edge 24 tilted by an indicated in Figure 5 tilting angle α. The tilting of the valve element 16 itself is indicated by reference numeral 56. With the tilting of the seat edge 54 to the inner side 40 of the sleeve-shaped, outer valve element 16, the seat angle also undergoes a change. Due to the widening 60 of the radial extension 48, the seat angle at applied system pressure p _sys , as shown in Figure 5, changed so that the sleeve-shaped, outer valve element 16 tilts on the inside and thus on the guide diameter 64, ie the inner diameter of the sleeve-shaped trained, outer valve element 16 seals.

Due to the geometry of the valve seat region of the sleeve-shaped, outer valve element 16 shown in FIGS. 4 and 5, such a deformation is achieved that the surface pressure on the inner side 40 of the valve element 16 concentrates on the inner edge of the seat 18. As a result, a rolling of the seat diameter shown in FIG. 3 in the radial direction outwards is compensated, ie the formation of the rolling surface 32 shown in FIG. 3 is omitted, as is a pressure infiltration 30 of the seat from the inside thereof, ie the area acted upon by the system pressure p _sys ,

Due to the fact that in a widening 60 of the radial extension 48, which is preferably made as Kompensationsnut, a concentration of the surface pressure on the inner side 40 of the valve element 16, 16 maximum axial force is generated on the inside of the valve element.

As shown in Figure 5, a valve seat line 62 tilts the guide.

As can be seen from FIG. 5, the inner conical surface on the lower end side of the sleeve-shaped valve element 16 is tilted relative to the non-pressurized state 52 in the pressurized state 54 by the tilting angle α. In the pressurized state 54, the tilt angle α, which the valve seat line 62 forms with the axis of symmetry 12, increases. Due to this, in the worn state, the valve touches element 16 the seat 18 on the valve guide 22 on the seat edge 24; ie at the inner edge. Due to the tilting, the seat angle also changes when the system pressure p _{sys is applied} , so that the maximum sealing force is generated on the inside 40 of the sleeve-shaped valve element 16 received on the outside of the valve guide 22. In a preferred embodiment of the illustrated in Figures 4 and 5, can be acted upon by the system pressure radial extension 48 above the seat 18, a targeted deformation in the valve element 16 is introduced. In the illustration according to FIGS. 4 and 5, the valve element 16 is designed as an external, sleeve-shaped valve element 16. However, other geometries of the pressure compensated switching valve are conceivable in which the seat 18 is located at the top or it is an inwardly opening valve or the like. The radial extension 48 has a distance 46 from the seat edge 24 corresponding, for example, to the radius R _N , compare reference numeral 50 in FIGS. 4 and 5. Typical values for the distance A _N 46 are between 0.2 and 2 × R _N. While in the illustrations according to Figures 4 and 5, the radial extension 48 is attached to the inner side 40 of the sleeve-shaped, outer valve element 16, this may be formed instead of the valve element 16 on the valve guide 22 and the valve member. While the measures proposed according to the invention in the region of the seat 18 are described above with reference to FIGS. 1 to 5 in the description by way of example with reference to a switching valve 10 with an outflow to the outside and an outboard valve element 16, the measures taken can also apply to any other pressure compensated switching valve be transferred in a different geometry.

Claims

claims

A control valve (10) for a fuel injector having a valve element (16) guided in a valve guide (22), and wherein the valve element (16) opens or closes a seat (18), characterized in that a radial extension ( 48) formed in the valve element (16) and is acted upon by the system pressure p _sys .

Second switching valve (10) according to claim 1, characterized in that the valve element (16) at the radial extension (48) from the high-pressure chamber (14) from system pressure p _{sys is} acted upon.

Third switching valve (10) according to claim 1, characterized in that the radial extension (48) is designed as a compensation groove in a radius R _N (50).

4. switching valve (10) according to claim 1, characterized in that the radial extension (48) in the valve element (16) at a distance A _N (46) from a seat edge (24) is arranged away.

5. switching valve (10) according to claim 1, characterized in that in the pressurized state (54) of the valve element (16) the surface pressure on the seat (18) on the seat edge (24) is concentrated.

6. switching valve (10) according to claim 4, characterized in that in the pressurized state (54) to the seat edge (24) adjoining seat surface with valve seat line (62) of the valve element (16) tilts.

7. switching valve (10) according to claim 4, characterized in that the distance A _N (46) of the radial extension (48) of the seat edge (24) 0.2 to 2 times a depth (50) of a radial extension (48).

8. switching valve (10) according to one or more of the preceding claims, characterized in that in the pressurized state (54) of the valve element (16) by a tilt angle α tilted seat edge (24) on a guide diameter (64) seals.

9. switching valve (10) according to one or more of the preceding claims, characterized in that at system pressure p _sys acted upon radial extension (48) the seat is tilted with the valve seat line (62) of the valve element (16) towards the inside (40).

10. switching valve (10) according to one or more of the preceding claims, characterized in that the contour of the seat (18) upon application of system pressure p _sys is deformed so that the surface pressure at the seat edge (24) is maximized.