WO1997027396A1

WO1997027396A1 - Pressure valve

Info

Publication number: WO1997027396A1
Application number: PCT/DE1996/002116
Authority: WO
Inventors: Christian Taudt; Helmut Simon
Original assignee: Robert Bosch Gmbh
Priority date: 1996-01-27
Filing date: 1996-11-07
Publication date: 1997-07-31
Also published as: KR100300508B1; DE59608762D1; CN1179197A; BR9607806A; KR19980702720A; DE19602906A1; CN1075165C; EP0817914A1; JP2000500838A; EP0817914B1

Abstract

Proposed is a pressure valve for installation in a supply line between a high-pressure chamber and an injection point, the valve having a length of pressure pipe (3) with a cylindrical cavity (5) in which a valve member (15) is fitted so that it can move longitudinally. The valve member has a sealing surface (29) operating in cojunction with a fixed valve seat (27) to control the cross-sectional area of the flow passage, the valve member being lifted off the seat, against the action of a spring (23), by the pressure acting in the direction of flow (1) in the supply line. Fitted in the valve member (15) is a return-flow throttle channel which equalizes the pressure when the valve is closed. In order to ensure precise setting of the control of the maximum flow-passage area by the pressure valve, the opening stroke of the valve member takes place in two stages, the valve member being controlled abruptly to move to the maximum flow-passage area position after moving a given distance through its stroke.

Description

Pressure valve

State of the art

The invention is based on a pressure valve according to the preamble of claim 1. Such pressure valves known from DE 40 37 465 AI are used in delivery lines between a high-pressure chamber having a high-pressure chamber and an injection point, preferably between an injection pump and an injection valve of an internal combustion engine. The pressure valve should ensure that the medium to be pumped, e.g. Fuel, reaches the injection point, or when the injection ends, the pressure supply to the injection point is interrupted when the pressure drops below the necessary injection pressure. In order to post-injection at the injection point due to reflective pressure waves in the enclosed volume between the injection point and

To avoid pressure valve safely and to relieve pressure in this line section has the known pressure valve also has a backflow throttle, via which the high pressure in the line section between the injection point and pressure valve can relax during the breaks between the individual injection phases.

For this purpose, the known pressure valve has a valve member which is axially displaceable in a pressure or pipe socket and which is held by a valve spring with its valve sealing surface in contact with a stationary valve seat. The opening movement of the valve member takes place through the high fuel pressure built up in the high-pressure chamber, there in the pump work chamber of an injection pump, which lifts the valve member against the restoring force of the valve spring from the valve seat, so that a flow cross-section at the pressure valve is opened, via which the fuel reaches the injection valve. To relieve the pressure on the injection-side delivery line part during the injection breaks, a backflow throttle bore is also provided in the valve member, which is formed at least by a longitudinal bore.

However, the known pressure valve has the disadvantage that the timing of the opening of the maximum flow cross-section at the pressure valve cannot be set precisely and reproducibly due to the changing hydraulic conditions, so that the injection timing at the injection point cannot be determined precisely enough, which the Quality of the mixture preparation and combustion in the combustion chamber of an internal combustion engine to be supplied can significantly affect.

Advantages of the invention The pressure valve according to the invention with the characterizing features of claim 1 has the advantage that the opening movement of the valve member of the pressure valve and in particular the time when the maximum flow cross-section on the pressure valve is controlled by the hydraulic conditions, for example hydraulic sticking of the valve member, is not impaired, this hydraulic gluing can now be used deliberately. This allows a constant, reproducible

Set the opening pressure or injection pressure at the pressure valve precisely. This is advantageously achieved by a 2-stage opening stroke of the valve member of the pressure valve, which enables a jump function in the opening stroke of the valve member.

For this purpose, the flow area in the opening direction on the valve member is suddenly increased after passing through a defined forward stroke of the valve member, which triggers a very rapid residual stroke movement of the valve member, so that the maximum opening cross section is opened very quickly.

The 2-stage opening stroke movement of the valve member is controlled in a simple manner via

Control recesses in the valve member, which are advantageously formed by control bores, the axial ends of the outlet openings on the lateral surface of the valve member form control edges, which cooperate with corresponding stationary control recesses. These fixed control recesses are advantageous Arranged way in a control sleeve inserted in the pressure port, which is easy to manufacture and assemble.

The cross-section on the valve member which is additionally flowed in the opening direction is in a simple manner by a

Ring collar formed, which delimits a pressure chamber which can be connected to the control recesses of the control sleeve.

To represent the jump function according to the invention on the pressure valve by means of a hydraulically controlled 2-stage opening stroke movement, other control geometries are also possible as an alternative to the embodiment variant shown in the description. In addition to the preferred application in an injection line between an injection pump and an injection valve, the pressure valve according to the invention can also be used in other delivery lines between a high-pressure source and an outlet point.

Further advantages and advantageous embodiments of the subject matter of the invention can be found in the description, the drawing and the patent claims.

drawing

An embodiment of the pressure valve according to the invention is shown in the drawing and is explained in more detail in the following description.

1 shows a longitudinal section through the pressure valve according to the invention in its closed position. Description of the embodiment

FIG. 1 shows a longitudinal section through a pressure valve designed as a backflow throttle valve, which is inserted into a delivery line (not shown in detail) between a high-pressure chamber and an injection line, the direction of flow when the pressure valve is open from the high-pressure chamber to the injection point being identified by the arrow 1.

The pressure valve has a tubular pressure nozzle 3, the through hole of which widens to form a cylindrical recess 5, which at its larger end facing the high-pressure chamber is replaced by a cylindrical one

Connection piece with a through hole 9 is limited. A control sleeve 11 is inserted into the recess 5, the inner diameter of which is divided into two areas of different sizes by means of a ring shoulder 13. A piston-shaped valve member 15 is guided axially displaceably in the control sleeve 11 and has an annular collar 17 at its upper end facing the injection point. The smaller-diameter stem part of the valve member slides in the lower portion facing the connector 7 with the control sleeve 11 and the annular collar 17 with its circumferential surface in the larger inner diameter portion of the control sleeve 11, the annular shoulder 13 of the control sleeve 11 interacting with one on the annular collar 17 formed lower ring end face 19 limits the immersion depth of the valve member 15 in the control sleeve 11. An annular space formed between the lower annular end face 19 and the annular shoulder 13 forms a pressure space 22.

On an upper annular end face 21 formed on the annular collar 17, a valve spring 23 engages, which on the other hand is supported on a bore shoulder 25 in the pressure port 3 and which holds the valve member 15 with its lower annular end face 19 in contact against the stationary annular shoulder 13 of the control sleeve.

The larger diameter area of the control sleeve 11 forms a valve seat 27, with which a valve sealing surface 29 formed by the circumferential surface of the annular collar 17 on the valve member 15 for controlling a

Flow cross-section cooperates at the pressure valve.

For a pressure equalization in the line parts of the delivery line adjoining the pressure valve when the pressure valve is closed, a backflow throttle duct is provided in the valve member 15, which is designed as a throttle bore 31 which penetrates the valve member 15 axially.

The throttle bore 31 in the valve member 15 is cut by a control bore 33 forming a control recess in the valve member 15, which is designed as a transverse bore in the exemplary embodiment. The control bore 33, the edges of which in the axial direction toward the valve member 15 form control edges at the two outlet openings, acts to control the stroke movement of the valve member 15

Control recesses in the control sleeve 11 together. This control recesses in the control sleeve 11 is initially formed by a first annular groove 35 in the inner wall area of the control sleeve 11, which is smaller in diameter, which in the exemplary embodiment is cut through two longitudinal bores 37 which, starting from the lower end face 39 of the control sleeve 11, open into the ring shoulder 13 in the area of the pressure chamber 22 and at the bottom Are closed at the end by means of a ball 41.

At the lower end facing the connector 7, a further annular groove 43 is arranged in the inner wall of the control sleeve 11, which cooperates with a lower edge 45 of the valve member 15 formed on the lower end face 47 of the valve member 15. The annular grooves 35 and 43 are preferably arranged in the control sleeve 11 so that they are run over simultaneously by the control bore 33 and the edge 45 of the valve member 15 during the opening stroke movement of the valve member 15.

For a simplified assembly and to reduce the hydraulic influences, the transitions between the lower ring end face 19 to the valve sealing surface 29 and the lower end face 47 to the valve member have bevels.

The pressure valve according to the invention works in the following way.

Before the start of the high pressure supply to the pressure valve (injection break), the valve spring 23 holds the valve member 15 with the annular collar 17 in contact with the ring shoulder 13 of the

Control sleeve 11, in which position the valve member 15 rests with its valve sealing surface 29 on the valve seat 27 and closes the flow cross-section. In this state, pressure compensation between the line parts of the delivery line takes place only to a limited extent via the throttle bore 31 in the valve member 15.

With the start of high-pressure delivery, a high pressure builds up on the pressure valve via the connecting piece 7, which acts on the valve member 15 on its lower end face 47 in the opening direction against the restoring force of the valve spring 23. Part of this medium under high pressure (preferably fuel) passes through the throttle bore 31 into the part of the cylindrical recess 5 facing away from the connector 7 and acts there on the entire upper end face of the valve member 15 including the upper ring end face 21, so that the first Phase of the opening stroke movement of the valve member 15 is very delayed.

After covering a certain Vorhubweges s of the valve member 15, the control bore 33 and the edge 45 of the valve member 15 overlap with the annular grooves 35 and 43, so that the high pressure suddenly continues through the longitudinal bores 37 in the pressure chamber 22 and there also the lower one Ring end face 19 is applied to the valve member 15 in the opening direction. The

Control bore 33 and the edge 45 can be opened simultaneously or alternatively one after the other, as shown in the exemplary embodiment.

This sudden increase in cross section of the

Flow cross-section on the valve member 15 in the opening direction now causes a sudden increase in the opening force and further a very rapid passage of the remaining stroke of the valve member 15, so that the valve member 15 with the valve sealing surface 29 now quickly emerges from the overlap with the valve seat 27 and releases the maximum flow cross section from the pressure chamber 22 to the recess 5.

The subsequent closing of the pressure valve takes place in a known manner by the termination of the high pressure supply to the pressure valve, as a result of which the valve member 15 of the

Valve spring 23 is pushed back into contact with the fixed ring shoulder 13, so that the valve sealing surface 29 again overlaps the valve seat surface 27. Pressure equalization at the pressure valve only takes place via the throttle bore 31.

Claims

claims

1. Pressure valve for installation in a delivery line between a high-pressure chamber and an injection point, with a pressure port (3) having a cylindrical recess (5), in which a pressure valve member (15), which has a valve sealing surface (29), is arranged to be axially displaceable which cooperates with a stationary valve seat (27) to control a flow cross-section and from which it can be lifted against the force of a valve spring (23) by the delivery pressure in the flow direction (1), one in the valve member (15)

Return flow throttle duct is provided, via which a pressure equalization takes place when the pressure valve is in the closed position, characterized in that control recesses are provided on the valve member (15) which, after having traveled through a certain pre-stroke path of the valve member (15) in the opening direction, have an inflow cross section on the valve member (15) which is enlarged in cross section. Release in the opening direction.

2. Pressure valve according to claim 1, characterized in that the piston-shaped valve member (15) has an annular collar (17), the peripheral surface of which the valve sealing surface (29) The valve member (15) is guided in a control sleeve (11) which is inserted into the cylindrical recess (5) of the pressure port (3) and which forms part of the axial inner wall of the valve seat (27).

3. Pressure valve according to claim 2, characterized in that the valve member (15) has at least one control bore (33) which exits the Rückstrδmdrosselkanal (31) cutting on the lateral surface of the valve member (15) and after passing through a certain valve member stroke movement in

Overlap with a control channel in the control sleeve (11), which opens into a pressure chamber (22) delimited by the collar (17).

4. Pressure valve according to claim 3, characterized in that the control sleeve (11) has a stepped inner diameter, with a ring shoulder (13) at the cross-sectional transition a contact surface for the counter-flow direction (1) pointing with the pressure valve open lower ring end face (19) of the collar (17) on the valve member (15).

5. Pressure valve according to claim 4, characterized in that the control channel in the control sleeve (11) is formed by at least one longitudinal bore (37) which, starting from the lower, the flow direction (1) with the pressure valve open opposite end face (39) of the control sleeve (11) opens into the pressure chamber (22) at the ring shoulder (13) and is cut by at least one ring groove (35) on the inside diameter of the control sleeve (11), which in turn can be passed over by the control bore (33) in the valve member (15).

6. Pressure valve according to claim 5, characterized in that the longitudinal bore (37) is closed at its lower end facing the end face (39).

7. Pressure valve according to claim 6, characterized in that the longitudinal bore (37) is closed by means of an inserted ball (41).

8. Pressure valve according to claim 5, characterized in that at the lower end face (39) near the end there is a further annular groove (43) on the inside diameter of the control sleeve (11) which cuts the longitudinal bore (37) with a lower edge (45) cooperates on the valve member (15), an additional overflow cross-section to the pressure chamber (22) being opened when the lower edge (45) is immersed in the further annular groove (43).

9. Pressure valve according to claim 2, characterized in that the in the flow direction (1) pointing when the pressure valve is open, the upper annular end face (21) of the annular collar (17) on the valve member (15) is acted upon by the valve spring (23), which is on the other hand on a stationary stop (25) is supported in the pressure port (3).

10. Pressure valve according to claim 2, characterized in that a chamfer is provided at the transition between the lower end face (47) of the valve member (15) to the valve member and at the transition between the lower ring end face (19) to the collar (17).