DE102004018359B4 - Hydraulic actuator of particular gas exchange valves of an internal combustion engine - Google Patents

Abstract

Hydraulic actuator of, in particular, gas exchange valves of an internal combustion engine, in which - an actuator, in particular the plunger of the gas exchange valve, can be displaced between a first and second end position as a function of a variable, chambered hydraulic fluid volume, - the chamber volume changes proportionally to the hydraulic fluid volume change, - to that of the hydraulic fluid acted upon chamber a force independent of the hydraulic fluid acts in the direction of a chamber volume reduction, - the change in the chambered hydraulic fluid volume is carried out by an accumulation volume control of a hydraulic fluid volume flow flowing through the chamber, - the hydraulic volume flow leaving the chamber can be changed by a flow valve, characterized in that the flow valve as a electrical switching valve (1) is designed which enables at least three switching positions, namely a first (C) for a high, a second (B) for a medium, predeterminable volume flow and a third (A) for a volume flow interruption.

Description

The invention relates to a hydraulic actuator of particular gas exchange valves of an internal combustion engine according to the preamble of patent claim 1.

Such a hydraulic actuator is off WO 02/077421 A2 known.

From the EP 1 087 109 A2 is another valve train for a valve of an internal combustion engine known. In this case, a closing spring is provided, which acts on the valve in the closing direction and a throttle, via which a portion of the pressurized fluid during the closing movement flows out of a cylinder chamber

From the CH 407 648 is another valve train for a valve of an internal combustion engine known.

When using this known actuator for actuating the gas exchange valves of an internal combustion engine, the hydraulic fluid flowing out of the volume-variable hydraulic chamber flows through a control valve. With this control valve, it is possible to change the speed of the outflowing hydraulic volume flow. This in turn makes it possible to reduce the hydraulic chamber volume in a first phase very quickly and in a second, final phase much slower. With reference to the actuation of a gas exchange valve by such an actuator, this means that closing of a gas exchange valve in a first phase can be done with a high closing speed and in a second final phase of a significantly lower closing speed. In this way, the valve on the one hand on the one hand close quickly and on the other hand can be avoided by a low closing speed to complete the closing a hard impact of the valve disk on the valve seat ring. Instead of an undesirable hard impact, a virtually impact-free application of the valve disk to its valve seat can be achieved.

The previously proposed for the hydraulic outflow control valves require a relatively high effort in terms of design and usable functional elements. In addition, they are susceptible to faults and therefore do not guarantee a completely reliable permanent use.

The invention is concerned with the problem of providing a simpler constructed and absolutely reliable functioning regulating valve for discharged from the hydraulic fluid chamber hydraulic fluid.

This problem is solved primarily by the execution of a generic actuator according to the characterizing features of claim 1.

Advantageous and advantageous embodiments, which will be discussed in more detail below, are the subject of the dependent claims.

The invention is based on its use for actuating gas exchange valves of an internal combustion engine on the general idea to achieve a movement delay of the gas exchange valve in the final phase of closing by a switching valve, which is preferably operated electrically and with the three switching states are possible. These three switching states are a flow barrier, a flow restriction and a predetermined maximum possible flow. The state of the flow barrier is given when opening the gas exchange valve. At the beginning of closing the gas exchange valve, the desired maximum flow is switched. At the end of the closing of the gas exchange valve, that is, when a predetermined closing distance and thus entry into the final closing phase, the throttled switching state is activated. This "braking function" construction can be achieved in various ways. Further details on the function of the invention and on various structural embodiments are set forth below with reference to drawn functional diagrams and constructive examples.

In the drawing show

1 a functional representation of a switching valve according to the invention when used in a hydraulic actuator for a gas exchange valve of an internal combustion engine,

2 A first embodiment of an electrical switching valve with a throttled flow-through capability in the de-energized state,

3 a second embodiment in the manner of the example in 2 , but with a complete flow lock in the de-energized state,

4a the switching valve after 2 in a flow-locked state,

4b the switching valve after 2 in a state switched on unhindered flow,

5 a third embodiment of a switching valve with a built-in pressure relief valve for switching between a throttled and unthrottled flowability of the switching valve,

6 a fourth embodiment of a switching valve with an exclusively dependent on the position of an electric motor-driven closure element operating state between unhindered and throttled flowability,

7a A fifth embodiment of a switching valve with a pressure-compensated electromotively displaceable closure element,

7b the execution of a switching valve after 7a with a sliding seat sealing function that can be realized by the closure element,

8th A sixth embodiment of the switching valve with a pressure compensation during the actuation of the closure element,

9 . 10 Modifications of the switching valve design according to 8th ,

Fig. 1

With an inventive electrical switching valve 1 becomes the hydraulic drain from a hydraulic fluid chamber 2 regulated. The hydraulic fluid chamber 2 is variable in volume and part of an actuator for a gas exchange valve 3 an internal combustion engine, not shown in detail. Shown by the gas exchange valve 3 are the valve lifters 4 with a valve plate 5 one end and one displacer 6 as a movable wall of the hydraulic fluid chamber 2 other end. The valve plate 5 closes against a motor-side valve seat 7 , The valve lifter 4 is via a compression spring 8th in the closed position of the gas exchange valve 3 loaded. The hydraulic fluid chamber 2 has an access 9 and a finish 10 for hydraulic fluid to be supplied and dis- charged.

The fundamental function of in 1 shown actuator is the following.

By an example in WO 02/077421 A2 Volume flow variable conveying pump described in more detail is hydraulic fluid through the access 9 into the hydraulic fluid chamber 2 introduced at high pressure, causing the displacer 6 for opening the gas exchange valve 3 to increase the hydraulic fluid chamber 2 is displaced. During this filling phase, the switching valve locks 1 an outflow of hydraulic fluid through the outlet 10 from the hydraulic fluid chamber 2 , The switching valve 1 is in this phase deviating from the graphic representation in the switching position A.

After fully open gas exchange valve 3 that is at maximum through the displacer 6 adjusted volume of the hydraulic fluid chamber 2 becomes the switching valve 1 switched to its switching position C, in the maximum possible outflow of hydraulic fluid from the hydraulic fluid chamber 2 on the departure 10 and through the switching valve 1 can follow through.

Before the gas exchange valve 3 closes, that is before the valve plate 5 the associated valve seat 7 contacted, the switching valve 1 switched to its third switching position B. This switching position B causes a throttled outflow of hydraulic fluid from the hydraulic fluid chamber 2 , which in turn causes a delayed closing movement of the valve disk 5 in the direction of the associated valve seat ring 7 results. This delayed closing movement shortly before the final closing of the gas exchange valve ensures the avoidance of a hard impact of the valve disk 5 on the valve seat 7 ,

The aforementioned operations, namely "open valve" (I), "close valve without brake function in a first closing phase" (II) and "close valve in a closing phase with brake function" (III) is shown in a diagram on the right in FIG 1 shown. Plotted there are on the abscissa the closing time t and on the ordinate the closing y.

The application of the hydraulic fluid chamber takes place in an oscillating manner in the rhythm of the plunger movement taking place in the gas piston valve.

Fig. 2

In 2 is the in 1 only in the form of a switching symbol reproduced switching valve 1 shown in a first structural embodiment.

In a valve housing 11 is in a flow room 12 that comes from the hydraulic fluid chamber 2 flowing through hydraulic fluid, a closure element 13 stored displaceably between an open and closed position. In the flow room 12 introduces an inflow opening for incoming hydraulic fluid 14 , The outflow of hydraulic fluid from the flow space 12 takes place through a drain opening 15 , A compression spring 16 loads the closure element 12 Closing effective, with the compression spring 16 on the valve body 11 supported as an abutment.

For cooperation with the closure element 13 is in the switching valve 1 an electric actuator 17 intended. In detail this actuator exists 17 from an electrically energized magnetic coil 18 and a magnet armature 19 , From the magnet armature 19 leads an actuating pin 20 in the direction of the closure element 13 , Although at the in 2 shown operating state of the switching valve 1 no contact between the actuating pin 20 and the closure element 13 is given, there is in such a contact in other operating conditions. Corresponding operating states will be explained below. The magnet armature 19 is by a magnet armature compression spring 21 loaded. This load is such that the armature 19 is pressed in one direction and thus in a position in which at a closed position of the closure element 13 no contact between the actuating pin 20 and the closure element 13 given is. This position takes the armature 19 in a de-energized solenoid 18 one. In this position is in a closed position of the closure element 13 a throttled flow through the switching valve 1 possible. This operating state corresponds to the switching position B of the switching valve 1 as specified in 1 , This throttled flow is achieved through a throttle channel 22 in the closure element 13 , In a state in which the actuating pin 20 the closure element 13 not contacted and thus the throttle channel 22 not closing, can through the feed opening 14 in the flow space 12 inflowing hydraulic fluid through the throttle channel 22 through the closure element 13 penetrate. In the drain hole 15 can the out of the throttle channel 22 escaping hydraulic fluid through an annular gap 23 drain, which is between the closure element 13 and the associated boundary wall of the flow space 12 is provided. Of course, it does not have a ring channel 23 Rather, each type of channel is sufficient, with the closure element closed 13 is flow-locked.

The operating state of the switching valve after 2 corresponds to that after the switch position B in 1 and is the valve closing phase III according to the in 1 associated diagram.

The switching valve 1 can its switching signals from a the plunger movement in the gas exchange valve 3 detecting displacement sensor (not shown).

Fig. 4a

In this figure, the switching state A ( 1 ) of the switching valve 1 shown.

In this state, the switching valve causes 1 a complete flow barrier. This condition prevails when the valve is opened (I) according to the diagram in 1 , This flow blocking condition is achieved by energizing the solenoid coil 18 achieved, causing the armature 19 the associated actuating pin 20 such against the closure element 13 expresses that the throttle channel 22 is closed. From the electric actuator 17 goes over its operating pin 20 such a closing force on the closure element 13 that an absolutely safe flow barrier is guaranteed with reference to the highest possible operating pressure of the hydraulic fluid. The operation of the electric actuator in this state is by a solenoid energized 18 given.

Fig. 4b

In this figure, the operating state C of the switching valve 1 shown in the hydraulic fluid can flow completely unhindered. This operating state prevails during the phase "Close valve without brake function" (II) according to the diagram in 1 ,

The required opening position of the closure element 13 is achieved when the solenoid is de-energized 18 by a pressure of the hydraulic fluid acting on the closure element 13 one opposite to this burdening compression spring 8th exercise greater power.

In the 2 . 4a . 4b in each case a diagram is shown to the right of the switching valve, in which the pressure of the hydraulic fluid in P and on the ordinate of the hydraulic volume flow Q are plotted on the abscissa. The upper curve is designated i = 0 and stands for the de-energized state of the magnetic coil 18 , A maximum current supply with i = max. corresponding to Q = 0 is congruent as a curve with the abscissa. At a pressure of the hydraulic fluid above the value P _{B / C} , an unhindered flow of hydraulic fluid can take place, which increases to a maximum value at maximum hydraulic fluid pressure. This area corresponds to the valve closing phase II in the diagram of FIG 1 , Below one on the switching valve 1 pending hydraulic fluid pressure P _{B / C,} the hydraulic fluid flows through the switching valve 1 throttled to achieve the operating phase III "close valve with brake function" in the diagram of 1 ,

With complete flow restriction, the operating state "open valve" (I) is as shown in diagram 1 in front.

Fig. 3

3 shows an embodiment of a switching valve 1 in the way of those in 2 , however with the difference that the magnet armature 19 its closure position with respect to the closure element 13 contrary to the execution 2 with de-energized magnetic coil 18 occupies.

Fig. 5

In this embodiment of the switching valve 1 is in the flow space 12 a closure element 13 ' provided, that of the magnet armature 19 opposite end of the actuating pin 20 forms. This closure element 13 ' can through the electric actuator 17 be moved between closed and open position. The drain opening 15 is an opening throttle channel 24 upstream upstream, that is, this opening throttle channel 24 lies between the flow space 12 and the outside of the switching valve 1 leading drain opening 15 , To this opening throttle channel 24 is a bypass 25 provided in which there is a pressure relief valve 26 located. Specifically, this pressure relief valve 26 designed as a spring-loaded ball with an associated valve seat, so that the pressure relief valve 26 In principle, a check valve of the type is.

This switching valve 1 works as follows.

Shown in the drawing is a switching state B as indicated in FIG 1 , The corresponding symbol is in 5 next to the representation of the switching valve 1 again informative indicated.

In the illustrated opening position of the closure element 13 ' is the magnetic coil 18 energized. The open position takes the closing element 13 ' by the spring load. At a pressure of hydraulic fluid below P _{B / C} according to the diagram, for example in 1 That is, in a valve closing state III according to diagram 1 the hydraulic fluid leaves the switching valve 1 over the opening throttle channel 24 through the downstream drainage hole 15 and only via the opening throttle channel 24 ,

If the hydraulic pressure increases above a value P _{B / C} (see diagram in eg 1 ) opens the pressure relief valve 26 in the bypass 25 to the opening throttle channel 24 , In this operating state is a maximum flow through the switching valve 1 given.

For a flow barrier in which the closure element 13 ' the inflow opening 14 completely closes, is the magnetic coil 18 to energize, thereby the armature 19 to operate accordingly.

Fig. 6

This embodiment constitutes a modification of the embodiment 5 The modification consists essentially in that no bypass 25 in the case of the execution 5 provided kind exists.

In the flow room 12 is one over the electric actuator 17 adjustable closure element 13 '' provided, on the one hand via the inflow opening 14 on the other hand, in its opening position opposite to the closing position, it can completely obstruct a main supply channel 27 from the flow space 12 to the drainage hole 15 blocked. In the latter state of the closure element 13 ' can be an outflow through the inflow opening 14 in the flow space 11 inflowing hydraulic fluid into the drain opening 15 exclusively via a throttle channel 28 respectively. This switching state corresponds to the valve closing phase with brake function (III) according to the diagram in 1 , The other two switching states are readily apparent from the graphic representation, so that they need not be further explained here. It should be noted with respect to this embodiment, only that here the throttle switching position at de-energized solenoid coil 18 given is. This means that for a flow barrier through the closure element 13 '' the magnetic coil 18 must be energized.

Fig. 7a and Fig. 7b

With regard to their basic construction, the statements in these two representations correspond to those in 6 ,

In the execution after 7a In principle, there is only one difference in that the closure element 13 '' can be adjusted by hydraulic pressure compensation by the electric actuator. To achieve this pressure equalization is on the actuating pin 20 of the electric actuator 17 a pressure compensation piston 29 provided and indeed within a guide channel 30 , On one side of the pressure balance piston 29 Hydraulic fluid is at the pressure within the flow space 12 on and on the other side through an additional channel 31 applied hydraulic back pressure, by the inflow 14 supplied hydraulic fluid can be generated. Flow control at the switching valve after 7a is with energized solenoid 18 given.

The execution after 7b differs from the one after 7a only in that the closure element 13 '' in its opposite closed positions each seals via sliding seats.

Fig. 8; FIGS. 9 and 10

These switching valve versions are based on the type according to the examples according to the 7a . 7b ,

In the execution after 8th is the closure element 13 '' again pressure balanced displaceable by the electric actuator 17 , The same construction and functional parts are each occupied by the reference numerals of the preceding embodiments. For a pressure equalization on the closure element 13 ' ensures the closure element by the actuating pin 20 and a pressure compensating piston 29 through penetrating connection channel 32 ,

This pressure compensating connection channel 32 also have the closure elements 13 '' the embodiments of the 9 and 10 on.

The difference in execution 9 towards those after 8th is that the closure element 13 ' on one of its two investment pages with an area 33 is designed for a sliding seat seal.

In the execution after 10 is the closure element 13 '' on both sides with areas 33 and 34 designed for each opposite sliding seat seals.

In the versions after the 8th to 10 is the pressure equalization on the closure element 13 '' achieved in a particularly simple manner. As a throttle channel there is a parallel to the inlet opening 14 extending throttle channel 35 ,

All features shown in the description and in the following claims may be essential to the invention both individually and in any desired form.

Claims (6)

Hydraulic actuator of particular gas exchange valves of an internal combustion engine, in which - an actuator, in particular the plunger of the gas exchange valve in response to a variable, chambered hydraulic fluid volume between a first and second end position is displaceable, - the chamber volume changes proportionally to the hydraulic fluid volume change, - to that of the hydraulic fluid acted chamber acting independent of the hydraulic fluid force in the direction of a chamber volume reduction, - the change of the chambered hydraulic fluid volume by a backlog volume control of a hydraulic fluid flowing through the chamber, - the chamber leaving hydraulic volume flow is variable by a flow valve, characterized in that the flow valve as a electric switching valve ( 1 ) is formed, which allows at least three switching positions, namely a first (C) for a high, a second (B) for a medium, predetermined volume flow and a third (A) for a flow interruption. Hydraulic actuator according to claim 1, characterized in that the electrical switching valve ( 1 ) is designed as a solenoid valve. Hydraulic actuator according to claim 1 or 2, characterized in that at least one of the switching positions is activated by a detected chamber volume change or as a changed detected chamber volumes. Hydraulic actuator according to claim 1, characterized in that the detecting device is a displacement sensor. Hydraulic actuator according to one of the preceding claims, characterized in that at least one of the switching positions (A, B) is activated as a function of the pressure of the chambered hydraulic fluid. Hydraulic actuator according to claim 5, characterized in that the pressure detection including a thereby triggered switching of the switching valve ( 1 ) by a hydraulic, integrated in the switching valve pressure compensator.

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