EP2027387B1 - Damping device for an oscillating component - Google Patents

Abstract

The invention relates to a damping device (7, 7a) for an oscillating component, in particular a valve (1), which is preferably an injection valve (2), of an internal combustion engine, said component being able to be hydraulically actuated by means of an actuation piston (3), wherein the actuation piston (3), preferably loaded with a restoring force (F), borders a pressure chamber (5) which can be charged with pressure by means of a pressure line (6) which carries a working medium, wherein the damping device (7, 7a) is arranged in the pressure line (6). In order to extend the service life while maintaining high opening and closing speeds, it is proposed that the damping device (7, 7a) has a damping piston (9, 9a) which can be longitudinally displaced in a cylinder (8, 8a) between two end positions, wherein at least one damping channel (11, 11a) is arranged in the damping piston (9, 9a), extending essentially in the longitudinal direction of the damping piston (9, 9a), which propvides a fluid connection between two opposing face sides (12, 13) of the damping piston (9, 9a) and wherein a one-way-restrictor (14, 14a) is arranged in the damping channel (11, 11a), the choke effect of which depends on the direction of flow.

Description

The damping device for an oscillating component, in particular a preferably designed as an injection valve valve of an internal combustion engine, which component is hydraulically actuated via an actuating piston, wherein the preferably loaded by a restoring force actuating piston adjacent to a pressure chamber, which is acted upon via a pressure medium leading to a working pressure line , wherein the damping device is arranged in the pressure line, wherein the damping device comprises a damping piston in a cylinder between two end positions longitudinally displaceable, wherein in the damping piston at least one substantially extending in the longitudinal direction of the damping piston damping channel is arranged, which two mutually remote end faces of the damping piston with each other strömungsverbindet, and wherein in the damping channel, a throttle check valve is arranged, the throttling effect of the flow direction depends.

From the EP 1 335 125 B1 For example, there is known a damping device for effecting damping of the opening movement of a needle valve, which is pushed down by supplying fuel under pressure into a pressure control chamber and lifted by discharging the fuel from the pressure control chamber. In this case, a damping element is slidably supported on the needle valve. A damping chamber is formed between the damping element and the needle valve and is filled with fuel. Through a branch passage, fuel can be taken from the interior of the damping chamber and discharged outside the chamber. By the damping device, a constant damping of Ventilnadelhubes can be achieved.

The GB 2 138 884 A describes an injection valve for an internal combustion engine with an actuating piston having a damping device, wherein the valve body of the injection valve is hydraulically actuated. The valve body is mounted axially displaceable and can be opened against the restoring force of two springs. The fuel flow from the housing into the chamber of the first spring chamber is throttled by stroke-dependent adjustable openings in order to dampen the valve opening. Measures for damping the closing movement are not provided.

The disadvantage is that in damping devices with a continuous damping characteristic, the closing or opening time of the valve needle is delayed so that shallower opening and / or closing edges of the Nadelhubkurve arise. Out For reasons of combustion optimization, steep opening and closing edges are desirable. High closing speeds, however, lead to high contact speeds of the valve needle on the valve seat, which adversely affects the life of the valve. In addition, it comes to disturbing sound effects.

The object of the invention is to avoid these disadvantages and to reduce the placement speed of an oscillating component on a seat, in particular a valve on the valve seat, without significantly delaying the closing duration of the valve.

According to the invention this is achieved in that the damping device is designed as a closing damper, wherein the throttle resistance of the throttle check valve in the flow direction of the working medium at opening of the component is lower than in the reverse direction and that the damper is preceded by an opening damper, which preferably is identical to the closing damper trained opening damper compared to the closing damper with respect to the flow is oriented oppositely oriented.

It is preferably provided that a spring acts on the damping piston in the opening direction of the throttle check valve, which presses the damping piston into a first end position corresponding to the rest position.

The initial position of the damping device is defined by acting on the damping piston in the opening direction of the throttle check valve, a spring which presses the damping piston in a first end position corresponding to the rest position. During the opening stroke of the valve, the pressure line is pressurized again, wherein the check valve is opened within the throttle piston. The actuating medium can thus be supplied very quickly to the actuating piston both through the bypass line, as well as through the open check valve, whereby the valve is opened according to the selected characteristic. The amount of pressure of the actuating medium is an essential parameter for the opening characteristic of the valve.

The closing of the valve is initiated by lowering the pressure in the pressure line. In this case, the damping piston is displaced by its predefined stroke counter to the force of a counteracting spring up to a stop from an end position corresponding to the rest position into a second end position. In this case, the hydraulic medium is pushed back by the spring-loaded actuating piston. As a result, a high closing speed of the valve can be achieved in a first closing area. As soon as the damping piston abuts against the stop, the sudden pressure relief stopped on the actuating piston, since the working fluid can flow only through the bypass valve bypassing the non-return valve whose throttle cross-section defines the Aufsetzgeschwindigkeit the valve. The second closing range therefore results from the greatly throttled outflow of the actuating medium through the bypass channel within the throttle piston. After placing the valve on the valve seat and pressure relief compensation between the two end faces of the throttle piston is brought by the spring back to its original position.

It has been shown that the closing damper also has an advantageous effect on the post-swinging of the valve after the opening process. A further improvement of the Nachschwingverhaltens after opening the valve can be achieved if the damper is preceded by an opening damper, wherein the preferably constructed identical with the closing damper opening damper in comparison to the closing damper with respect to the flow is arranged oppositely oriented. In this case, the damping piston of the opening damper is held by a spring counter to the opening flow direction of the working medium in an initial position. The check valve of the opening damper closes in the opening flow direction of the working medium and opens in the closing direction of the working medium. If the pressure in the pressure line increases, the damping piston of the opening damper is displaced against the force of the spring in its second end position, which is defined by a stop. By the deflection of the piston, the pressure downstream of the opening damper is transmitted freely, whereby the check valve of the closing damper is opened. During this phase, the opening pressure is transferred virtually unthrottled to the actuating piston of the nozzle needle, so that the valve needle is opened very quickly in the first opening phase. Once the damping piston of the opening damper rests against its stop, the sudden increase in pressure in the pressure line downstream of the opening damper is stopped or greatly reduced, since the actuating medium can only flow through the bypass channel of the opening damper. Due to the throttle resistance of the bypass channel, the opening characteristic is determined in the second opening phase of the valve needle. There is thus a slowing of the opening movement of the valve at the end of the opening phase, so that over- and Nachschwingerscheinungen be largely prevented.

Fig. 1

eine Ausführungsvariante einer erfindungsgemäßen Dämpfungsein- richtung in einem Längsschnitt;

Fig. 2

bis Fig. 7 eine erfindungsgemäße Dämpfungseinrichtung für einen oszillierenden Bauteil in verschiedenen Stellungen;

Fig. 8

eine weitere konstruktive Ausführungsvariante der Dämpfungsein- richtung in einem Längsschnitt und

Fig. 9

eine Ventilhubkurve.

The invention will be explained in more detail below with reference to FIGS. They show schematically:

Fig. 1

a variant of a damping device according to the invention in a longitudinal section;

Fig. 2

to Fig. 7 a damping device according to the invention for an oscillating component in different positions;

Fig. 8

a further constructive variant of the damping device in a longitudinal section and

Fig. 9

a valve lift curve.

The damping device 7 is suitable for oscillating components, in particular for valves 1, for example for an outwardly opening injection valve 2 of an internal combustion engine. Fig. 1 shows an injection valve 2 with a damping device 7 for an internal combustion engine. The valve 1 of the injection valve 2 is opened by a longitudinally displaceable actuating piston 3 by means of a hydraulic working medium and closed by a closure force F on the actuating piston 3 performing closing spring 4. The axially longitudinally displaceable actuating piston 3 is adjacent to a pressure chamber 5, in which opens a pressure line 6 for the working fluid.

In the in the Fig. 2 to Fig. 7 shown positions of the cooperating with an oscillating component actuating piston 3 is arranged in the pressure line 6 designed as a closing damper 25 damping device 7. The damping device 7 has a longitudinally displaceable in a cylinder 8 damping piston 9, which is held by a spring 10 in a rest position corresponding first end position, as in Fig. 1 is apparent. Within the damping piston 9, a damping channel 11 is arranged, which fluidly connects the two end faces 12, 13 of the damping piston 9, wherein the end faces 12, 13 border on spaces in which the pressure line 6 opens. In the damping channel 11, a throttle check valve 14 is arranged, which is formed in the embodiment by a by-passable via a bypass passage 15 check valve 16. The check valve 16 is pressed by a valve spring 17 against the effective direction of the spring 10 against a valve seat 18, wherein in the closed state of the check valve 16, the flow around the bypass channel 15 is possible. The bypass channel 15 has a defined throttle resistance, which is denoted by the reference numeral 19 in FIG Fig. 2 to Fig. 8 is indicated. With reference numeral 20, the throttle resistance of the damping channel 11 is designated.

Upstream of the damping device 7, a control valve 21 is arranged in the pressure line 6. The damping piston 9 has a diameter d ₁ and can be moved within the cylinder 8 by the stroke h ₁ . The reference numerals d ₂ and h ₂ , the diameter, or the stroke of the actuating piston 3 are designated.

When designed as a closing damper 25 damping device 7, the check valve 16 opens in the flow when opening the valve needle 1 from the working fluid direction.

In Fig. 9 a lift curve of the valve 1 is shown, wherein the stroke h is plotted against the time t. With the arrows II, III, IV, V, VI and VII are different opening phases of the valve 1 according to the FIGS. 2 to 7 shown.

Fig. 2 shows the valve 1 at rest according to the arrow II in Fig. 9 , The actuating piston 3 is loaded by a force F in the closing direction of the valve 1, for example by the closing fields 4. The damping piston 9 is in its first end position defined by the spring 10, which corresponds to its rest position, the check valve 16 is closed.

Fig. 3 shows the opening phase of the valve 1 according to the arrow III in Fig. 9 , By increasing the pressure p _B in the pressure line 6 to the pressure p _medium , the check valve 16 is opened, whereby a maximum flow cross section through the damping channel 11 in the damping piston 9 is released for the actuating _medium (p _B > p _A ). Due to the resulting increase in pressure in the pressure chamber 5, the actuating piston 3 according to the arrow P in Fig. 3 moved down, the valve 1 thus opened. With valve fully open 1 - arrow IV in Fig. 9 - There is a pressure equalization p _A = p _B on both end faces 12, 13 of the damping piston 9, which is why the check valve 16 is closed by the valve spring 17 ( Fig. 4 ). In this phase, the pressure p _{medium is held} in the pressure line 6. The closing operation of the valve 1 according to arrow V in Fig. 9 is introduced by pressure reduction in the pressure line 6 via the control valve 21, as in Fig. 5 is shown, so that p _B <p _A. In a first closing phase 22 of the damping piston 9 is moved according to the arrow P ₁ against the force of the spring 10 due to the pressure difference p _A -p _B on both sides of the damping piston 9 upwards until the damping piston 9 rests against a stop 24. The hydraulic medium is thereby pushed back by the prestressed actuating piston 3 in the pressure line 6, wherein the actuating piston 3 moves with the medium. The movement of the medium is designated P ₂ . The stroke h _{2 of} the damping piston 9 must be such that the damping piston 9 rests against the stop 24 before the valve 1 strikes its valve seat. After resting the damping piston 9 on the stop 24, the pressure p _A increases rapidly in the working space 5. The pressure p _A can be reduced only slowly corresponding to the throttle resistance 19 of the bypass channel 11, which is why a significant slowing down of the closing movement of the valve 1 occurs. This second closing area is in Fig. 9 denoted by 23. The corresponding phase of the damping device 7 is in Fig. 6 shown. By suitable tuning of the throttle resistors 19, 20 is too hard Opening the valve 1 prevents the valve seat, but still allows a total of fast closing within a short period of time.

After reducing the pressure difference p _A -p _B on both sides of the damping piston 9 of the damping piston 9 is moved back by the spring 10 in its rest position, as in Fig. 7 is shown.

By the closing damper 25 and valve swing movements are reduced after opening the valve 1. A further reduction of the ringing of the valve 1 can be achieved if the shock absorber 25 is preceded by an opening damper 26 in the pressure line 6, as in FIG Fig. 8 is shown. The opening damper 26 is of identical design to the closing damper 25, but arranged inversely oriented in the pressure line 6, wherein the check valve 16a of the throttle check valve 14a now opens against the direction which flows through the working fluid when opening the valve 1. The spring 10a of the opening damper 26 acts on the damping piston 9a of the opening damper 26 in a direction opposite to the spring 10 so that it is pressed counter to the opening flow direction of the working medium in a rest position corresponding to its first end position. The direction of the rest position is in Fig. 8 indicated by the arrows 27, 28.

The effect of the opening damper 26 is analogous to the Fig. 2 to Fig. 7 , but in the opposite direction. If pressure is applied to the pressure line 6, the damping piston 9a of the opening damper 26 is moved out of the rest position against the force of the spring 10a until the damping piston 9a bears against the stop 24a. During this phase, the opening pressure prevails in the pressure line 6 downstream of the opening damper 26 unhindered, the check valve 16 of the damper 25 is opened and opened as a result of the valve 1 by the increasing pressure in the pressure chamber 5 very quickly. As soon as the damping piston 9a of the opening damper 26 bears against the stop 24a, the opening movement of the valve 1 is substantially slowed down, since the further pressure build-up is determined by the throttle resistance 19a of the bypass channel 15a of the opening damper 26. As a result, overshoot of the valve 1 is prevented. At full valve lift of the valve 1 there is a pressure equalization on both sides of the damping piston 9a, so that the damping piston 9a is moved back by the spring 10a back to its rest position according to the arrow 28. The closing phase follows, as already on the basis of Fig. 2 to Fig. 7 explained.

Claims (4)

1. A damping device (7, 7a) for an oscillating component, especially a valve (1) of an internal combustion engine which is preferably arranged as an injection valve (2), which component can be actuated hydraulically via an actuating piston (3), with the actuating piston (3) which is loaded by a restoring force (F) being adjacent to a pressure chamber (5) which can be supplied with pressure via a pressure line (6) guiding a working medium, with the damping device (7, 7a) being arranged in the pressure line (6), with the damping device (7, 7a) having a damping piston (9, 9a) which is displaceable in a longitudinal manner in a cylinder (8, 8a) between two end positions, with at least one damping conduit (11, 11a) which extends substantially in the longitudinal direction of the damping piston (9, 9a) being arranged in the damping piston (9, 9a), which damping conduit connects in respect of flow two mutually averted face sides (12, 13) of the damping piston (9, 9a), and with a throttle check valve (14, 14a) being arranged in the damping conduit (11, 11a), the throttle action of which depends on the direction of flow, characterised in that the damping device (7, 7a) is arranged as a closing damper (25), with the throttle resistance of the throttle check valve (14) being lower in the direction of flow of the working medium upon opening of the component than in the opposite direction, and an opening damper (26) is provided upstream of the closing damper (25), with the opening damper (26), which is preferably arranged in a structurally identical manner with the closing damper (25), being arranged to be oriented in an opposite manner with respect to the through-flow in comparison with the closing damper (25).
2. A damping device (7, 7a) according to claim 1, characterised in that the throttle check valve (14, 14a) has a check valve (16, 16a) that can be circumvented via a bypass conduit (15, 15a).
3. A damping device (7, 7a) according to claim 1 or 2, characterised in that a spring (10, 10a) acts upon the damping piston (9, 9a) in the opening direction of the throttle check valve (14, 14a), which spring presses the damping piston (9, 9a) to a first end position corresponding to the idle position.
4. A damping device (7, 7a) according to one of the claims 1 to 3, characterised in that the stroke of the component which effectively causes the stroke of the damping piston (9, 9a) by volumetric displacement is smaller than the maximum stroke of the component.

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