EP1600627A1 - Control valve - Google Patents

Abstract

The control valve (1) has a pressure chamber (12) with a high pressure port (15) and a low pressure port (16). The mouth (17) of the LP port is located in the casing wall (13) which forms a stop for the shut-off head (4) of a control piston (2). The diameter (6) of the shut-off head is greater than the guide diameter (7) of the control piston, and the step diameter which corresponds to the offset from the shut-off diameter to the guide diameter lies in the pressure chamber.

Description

It is known for controlling injection injectors for Internal combustion engines to use a control valve that the Actuating movements of the valve closing member controls. One such control valve has a liftable, Control piston, for example, solenoid or piezobetätigt can be. The control piston lies with a front side in the Area of a closing head in a pressure chamber, on the one throttled, from a control chamber of the valve closure member outgoing high-pressure side inlet opens, and of the a throttled and controlled by the control piston Expired. The control chamber of the valve closure member is in throttled connection with a high-pressure line. The Actuating movements of the control piston cause pressure changes in the adjacent to the valve closure member control chamber and corresponding forces on the back of the Valve closing member. Is the drain of the pressure chamber open, the pressure in the pressure chamber is reduced while at the same time the back of the valve closure member acting pressure decreases, resulting in the opening of the valve closure member. If the drain is through the closing head of the control piston closed again, the pressure in the pressure chamber and increases at the same time in the on the back of the valve closure member lying control room, causing the closing of the Valve closure member leads.

Such a control valve is for example in the US 5,934,643. The control piston is at one of Housing wall opposite closing head with a Sealing edge formed, which, at the stop on the housing wall located, a pressure chamber against the mouth of a Low pressure connection seals. The on the perimeter of Control piston located pressure chamber communicates with the High pressure connection in conjunction with that on the Rear side of the valve closing member of the injector lying Control room leads, in turn, over a throttled Supply with a fuel-carrying high-pressure channel in Connection stands. The on the front side of the closing head lying sealing edge has a flat in one embodiment annular abutment surface resting on the flat housing wall supported. In another embodiment, the sealing edge formed with a cutting edge. In this latter However, the low-pressure connection will be replaced by a Inner bore of the control piston formed. The outer diameter of the sealing edge bearing locking head corresponds obviously the guide diameter of the control piston. at Such designs will result in time Reduction of the closing force with the consequence of a reduced sealing effect, because of the wear the sealing edge of the sealing diameter becomes smaller, something a complete failure due to no longer closing can cause sufficient forces. The reduction of Closing force is due to the fact that an additional Surface is pressurized with fuel pressure, thereby countering the closing direction acting forces arise through the Control valve spring can not be compensated.

The invention is based on the object, by increasing the Closing force a reliable seal even with longer Operating time and wear of the sealing edge to ensure.

This problem is solved by the in listed features achieved in that the Closing head diameter greater than the guide diameter of the Control piston is executed, and the diameter step, the the return from the closing head diameter on the Guide diameter corresponds, is arranged in the pressure chamber. As a result, the applied pressure in the pressure chamber acts on the Diameter stage, creating a force in the closing direction generated in addition to the closing force of a control valve spring becomes. Condition is that the sealing diameter greater than the guide diameter is what happens at one Closing head diameter according to the invention can be realized.

Advantageous embodiments of the invention are in the Subclaims specified.

The embodiment of the sealing edge according to claim 2 with semicircular cross section is particularly favorable in Regarding the flow behavior and the avoidance of Cavitation. At the same time, this education promises a high Resistance to wear or plastic deformation, because due to a large amount of material in the area immediately before and behind the sealing line a high mechanical strength exists.

According to the subclaims 3 to 7, the sealing edge has a sharp-edged abutment edge, a cutting edge made up of two is formed against each other inclined chamfers. The chamfers can while straight sections or convex sections be educated. Convex sections favor in and out Outflow behavior and help to prevent cavitation. More favorable flow coefficients that are achieved thereby also provide the ability to get the required stroke out.

According to claim 8, the between the tangents to the Bevels included in the cutting angle 90 ° or more but less than 180 °, preferably 140 ° to 179 °. Thereby a sharply defined investment cut is made.

On the other hand, it is in front of and behind the cutting edge Material accumulation at these relatively large angles is great enough to have high impact forces without strong plastic Deformations of the front and behind the cutting edge To be able to record material.

According to claims 9 and 10 are those of the tangents at the chamfers in the cutting edge and from the stop forming housing wall included angle between 0.5 ° and 20 °. Due to the relatively flat course of both bevels In turn, there is the advantage of low wear or less permanent deformation of the sealing Diameter performing cutting edge. Because the front and back the cutting large material accumulation causes a high strength. This will cause a shift of the sealing Reduced diameter, so that the change of the Closing forces during operation is also minimized.

The chamfers may have the same angle according to claim 11. Due to the symmetrical flattening of the cutting edge during operation a displacement of the sealing diameter inside or outside possible. To always have sufficient closing force is sufficient in this case Provide diameter stage.

By using against the sealing diameter outside chamfers a defined gap is formed, in the fuel pressure is applied. By varying the width the chamfer or the sealing diameter can at the Diameter stage according to claim 1 acting in the closing direction Force can be compensated more or less as needed. In order to There is an easy way to do that by the Control valve spring applied required closing force adapt by appropriate dimensioning of the chamfer.

The use of an outside bevel also has the Advantage that there is the possibility of the impact of expected wear on the sealing diameter a favorable choice of bevel angle combination so too affect that in operation by wear a Enlargement of the sealing diameter yields what is synonymous with an increase in the closing forces. This Result is achieved when the outside bevel after Claim 12 very flat and the inside chamfer something steeper (α <β). At a flattening of the cutting edge namely by plastic deformation namely the first outer chamfer sections with less light Distance to the contact surface in contact with the contact surface of the the sealing seat forming housing wall.

Conversely, a shift of the sealing can be Diameter inside to achieve if according to claim 13 the inside chamfer runs flatter than the outside Chamfer (α> β).

Apart from the chamfer angle, the shape of the chamfer can influence the Take the direction of displacement of the sealing diameter. According to claim 14, therefore, the angles of the chamfers and / or their shape chosen so that due to the im Operation expected wear an increase in the sealing diameter results. This will become one Reduction of closing forces counteracted during operation.

The sealing edge is according to claim 15 preferably on a Diameter corresponding to the guide diameter or is larger. The choice of the appropriate diameter is through through the control valve spring and the pressure forces achievable closing forces. With the choice of Sealing edge diameter also become the chamfer widths and thus the pressure forces acting on the control piston established.

According to claim 16, the sealing edge can also on a Diameter are smaller than the guide diameter is.

An embodiment of the invention is in the drawing and will be described in more detail below.

Fig. 1

eine Querschnittsansicht eines Injektors mit einem Steuerventil zur Steuerung des Ventilschließglieds;

Fig. 2

die Ausführung eines Steuerventils mit einem Steuerkolben nach dem Stand der Technik gemäß Figur 2a, wobei Figur 2b ein Detail der Figur 2a darstellt;

Fig. 3

eine schematische Darstellung eines Steuerventils nach der Erfindung;

Fig. 4

stellt, bestehend aus den Teilfiguren 4a bis 4d, verschiedene Ausführungsformen des erfindungsgemäßen Ventilschließkopfs des Steuerventils dar.

Show it:

Fig. 1

a cross-sectional view of an injector with a control valve for controlling the valve closing member;

Fig. 2

the embodiment of a control valve with a control piston according to the prior art according to Figure 2a, wherein Figure 2b shows a detail of Figure 2a;

Fig. 3

a schematic representation of a control valve according to the invention;

Fig. 4

represents, consisting of the subfigures 4a to 4d, various embodiments of the valve closing head of the control valve according to the invention.

In the injector shown in longitudinal section in Figure 1 serves a control valve 1, which with a control piston. 2 is designed to control the opening and Closing movements of the valve closure member 20. The control room 19 is via a throttle with a high-pressure channel in Compound containing pressurized fuel.

By the control valve 1, the control chamber 19 be relieved of pressure to a lifting movement of the Valve closure member 20 trigger, thereby characterized by his Valve seat 23 lifts. The pressure relief of the control room 19th is controlled by the control piston 2 of the control valve 1. The control piston 2 is provided with an actuator, for example an armature of a solenoid valve, not shown connected. By energizing the solenoid valve lifts the Control piston 2 against the force of the control valve spring 24 of from his seat and thereby gives a low pressure port 16 free. With the release of the low pressure port 16 falls the pressure in a pressure chamber 12, the over a High pressure port 15 communicates with the control room. After the energizing end, the control valve spring 24 pushes the Control piston 2 again sealingly against the valve plate 14, the a housing wall 13 of the pressure chamber 12 represents. The pressure in the Pressure chamber 12 and control chamber 19 increases and thus the am Valve closure member 20 acting in the closing direction force.

In the figure 2, which consists of the figures 2a and 2b, is the control piston 2 of the control valve 1 in the region of Sealing seat shown. The control piston 2 is in a Bore 3 guided longitudinally movable. The hole 3 is located in the control valve housing 11. The control piston 2 is located with a Part of the end face 10 on the valve plate 14 and sealingly covers the low pressure port 16. In the shown position prevents the control piston 2 the Transfer from a high pressure port 16 in the Pressure chamber 12 guided fuel to the low pressure port.

FIG. 2b shows the detail circled in FIG. 2a. To a certain operating time is formed by plastic Deformation as a result of the impact pulse or by Other wear, such as cavitation erosion, a Gap, leaving the actual sealing zone 5 inside emigrated. As is the case with the sealing diameter displaced inside, created by acting in the gap Fuel pressure against the control valve spring 24th directed pressure force, which lift the control piston 2 want. As a result, the sealing force is lower, the Fit seat leakage increases with inadmissible change of Control times and in extreme cases, the control piston 2 even completely raised, which leads to the failure of the control valve 1.

Figure 3 shows a control valve 1, which with a Control piston 2 according to the invention is designed, whose Closing head 4 formed with a closing head diameter 6 is greater than the guide diameter 7, on the the control piston 2 is guided in the bore 3. The 27th diameter stepping back from the Closing head diameter 6 on the guide diameter 7 corresponds, is in the pressure chamber 12. By the at the Diameter step 27 attacking pressure forces is the Sealing strength increased. The condition is that the sealing edge 5 on a larger diameter than the Guide diameter 7. When selecting the sealing edge diameter 5 of course, make sure that the magnets of the Solenoid applied tightening forces from the Control valve spring 24 and at the diameter stage 27th can exceed acting compressive forces. The poetic Diameter is from the housing wall 13 of the valve plate 14th and an end face 10 superior cutting edge of the Locking head 4 formed by two against each other inclined chamfers 8 and 9 is shown. The outside Chamfer 8 is the pressure prevailing in the pressure chamber 12 Exposed to fuel pressure, so here in the opening direction acting compressive forces act on the at the diameter stage 27 opposing pressure forces are opposite. By the Bevel width of the outer chamfer can thus be variable, without to change the control valve spring 24, different Realize sealing forces.

Furthermore, by different Bevel angle combinations and bevel shapes are determined, whether the sealing diameter in operation by plastic Deformation or other signs of wear of the Sealing edge enlarged or reduced. The sealing edge 5 or the sealing edge is divided by two formed inclined chamfers, an outer chamfer 8 and an internal chamfer 9. The tangents 25 and 26 to the Bevel 9 and 10 in the cutting edge form with the housing wall 12th an angle α and an angle β. The thus formed Angles are preferably in the range between 0.5 ° and 20 °. In principle, however, any other angles are conceivable. The angle between the tangents is preferably given to 179 to 140 degrees, so a relatively obtuse angle. This relatively obtuse angle has the advantage that on the one hand a sharply defined cutting edge is formed with a sealing line, which defines the sealing diameter. The front and back the cutting material lying but is also large enough that a high strength is achieved, so that the Flattening of the cutting edge during operation by plastic Deformation is minimized.

The angles α and β can be chosen to be the same size. By However, different choice of angles can be one Defined displacement direction of the sealing diameter become. It is assumed that the sealing Diameter shifts toward the shallower bevel, since the clear distance between chamfer and housing wall stop there is lower and at a plastic flattening of First cut the flatter bevel sections into place reach. So if an enlargement of the sealing Diameter is to be achieved in operation, the angle α at the outer bevel smaller than the angle β at the inner Bevel to choose. This increases over time the sealing force, as acting on the diameter stage 27 Compressive force is compensated to a lesser extent. Vice versa On the other hand, there will be a reduction of the sealing Diameter, if the inner bevel with a smaller angle β is formed as the angle α of outer bevel is.

The shift of the sealing diameter can also still depend on other factors. It is conceivable that the Displacement of the sealing diameter due to others Factors influencing the direction described above runs. Crucial is obviously how big the Support of the chamfer by the preceding and behind it Material material is. The shape of the chamfer can also be one Role-play.

The chamfers can not only with straight sections, but also be formed with a radius, as the figures 4a, 4b and 4d show. In the embodiment of Figure 4a is the outer chamfer convexly curved and the inner chamfer has a straight section. In training after FIG. 4b is the outer chamfer with a straight line Section and the inner chamfer 9 with a convex Section formed. In the embodiment of Figure 4c the chamfers are formed by two straight sections. at the formation of Figure 4d, the sealing edge 5 semicircular in cross section.

LIST OF REFERENCE NUMBERS

1

control valve

2

spool

3

drilling

4

closing head

5

sealing edge

6

Closing head diameter

7

Guide diameter

8th

Bevel, outside

9

Bevel, inside

10

face

11

Control valve housing

12

pressure chamber

13

housing wall

14

valve plate

15

High pressure port

16

Low pressure port

17

muzzle

18

High pressure passage

19

control room

20

Valve closure member

21 22

valve spring

23

valve seat

24

Control valve spring

25

Tangent, inside

26

Tangent, outside

27

Diameter step

Claims (16)

Control valve (1), with a pressure chamber (12) having a high pressure port (15) and a low pressure port (16), the mouth (17) of the low pressure port (16) in a the pressure chamber (12) limiting, the closing head (4 ) of an axially displaceable in a bore (3) out, by a control valve spring (24) in the closing direction loaded control piston (2) opposite housing wall (13) is arranged, which forms a stop for the closing head (4), wherein the closing head (4) an end face (10) with a sealing edge (5), with which the closing head (4) rests against the housing wall (13) and sealingly covers the mouth region (17) of the low-pressure connection (16) to form a sealing boundary, and wherein the closing head ( 4) can be displaced into a position raised from the housing wall (13) while the sealing boundary is removed,
characterized in that the closing head diameter (6) is greater than the guide diameter (7) of the control piston (2), and that the diameter step (27) corresponding to the return from the closing head diameter (6) to the guide diameter (7), in the pressure chamber ( 12) is located. Control valve according to claim 1,
characterized in that the sealing edge (5) is semicircular in cross section. Control valve according to claim 1,
characterized in that the end face (10) of the closing head (4) with two mutually inclined bevels (8, 9) is formed, which form a relative to the end face (10) projecting cutting edge. Control valve according to claim 3,
characterized in that the chamfers (8, 9) are formed of straight sections. Control valve according to claim 3,
characterized in that the chamfers (8, 9) are formed of a straight, radially inner and a convex, radially outer portion. Control valve according to claim 3,
characterized in that the chamfers (8, 9) of a straight, radially outer and a convex, radially inner portion are formed. Control valve according to claim 3,
characterized in that the chamfers (8, 9) are formed of two convex portions. Control valve according to one of claims 3 to 7,
characterized in that the angle included between tangents (25, 26) to the chamfers (8, 9) in the cutting edge is 90 degrees or more but less than 180 degrees, preferably between 140 and 179 degrees. Control valve according to one of claims 3 to 8,
characterized in that the angle α enclosed by a tangent (26) to the outer chamfer (8) in the cutting edge and by the housing wall (12) forming the stop is between 0.5 degrees and 20 degrees. Control valve according to one of claims 3 to 9,
characterized in that the angle β enclosed by a tangent (25) to the inner chamfer (9) in the cutting edge and by the housing wall (12) forming the stop is between 0.5 degrees and 20 degrees. Control valve according to claim 10,
characterized in that the angles α (27) and β (28) are approximately equal. Control valve according to claim 10,
characterized in that the angle α (27) is smaller than the angle β (28). Control valve according to claim 10,
characterized in that the angle α (27) is greater than the angle β (28). Control valve according to one of claims 3 to 12,
characterized in that the angles α and β and / or the shape of the chamfers are selected such that there is an increase in the sealing diameter due to the wear. Control valve according to one of claims 1 to 14,
characterized in that the sealing edge (5) lies on a diameter which corresponds to the guide diameter (7) or is larger. Control valve according to one of claims 1 to 14,
characterized in that the sealing edge (5) is located on a diameter which is smaller than the guide diameter (7).

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