EP1260680B1 - Hydraulic valve drive for 2 valves simultaneously in a diesel engine - Google Patents

Abstract

Pressure chambers are provided in the control piston (8) for the identical valves (4,5) and are connected through control ducts (11,12) to pressure supply lines (6,7) which are opened and closed through magnetic valves (91,0). The control pistons hold the engine valves (4,5) in a preliminary stage in the closed position (S) and in a following stage with a preliminary stroke. In a further stage the engine valves are adjustable into a maximum opening position through the control piston.

Description

Hydraulic control device for the same valves of a diesel engine, each having a valve stem and are associated with the spring means for acting in the valve closing direction and hydraulically controllable controls for acting in Ventilöffnungs- and / or closing direction, and the controls are held in a bridge, which with a Cylinder head is connected and the controls each comprise a functionally connected to the engine valves hydraulic cylinder with a pressurizing control piston which is adjustable in response to piston positions of the engine via controllable solenoid valves in several stages.

In a known manner four-valve cylinder heads are operated by means of a valve bridge, which connects two intake and exhaust valves, via a rocker arm, which is connected by means of a rocker arm mounted on the rod with a camshaft. Furthermore, DE 197 16 042 C1 discloses a hydraulic control device for at least one lifting valve of an internal combustion engine, which comprises a valve stem movable by two spring means acting against each other, wherein the valve stem can be hydraulically actuated in the region of its end position. The hydraulic control device includes a hydraulically controllable spring means, which is assigned a hydraulically acting auxiliary control member.

From WO 93/01399 an internal combustion engine with a control unit for engine valves is known, which are adjustable via control pistons, which are acted upon by means of electrically controllable valves with a corresponding control pressure. The control pistons are arranged together in a bridge, which is mounted on a cylinder head of the engine. The controllability of the control piston, the engine valves can be opened and closed as allow the acceleration or deceleration against the valve springs.

The object of the invention is to provide a hydraulic control device for globe valves of an internal combustion engine and a receptacle for controls of the device, whereby on the one hand a simple hydraulic control of the intake and / or exhaust valves of an internal combustion engine in the opening and closing direction is ensured according to the piston position and on the other the controls can be easily held on the cylinder head.

This object is achieved by the features of claim 1. Further advantageous features include the subclaims.

The advantages achieved by the invention are that via hydraulic controls of the control device, the inlet and / or exhaust valves of an internal combustion engine can be controlled accordingly in an opening and closing movement and for this purpose the controls are arranged in a fixedly connected to the cylinder head bridge and thus the controls can act directly and directly on the valve stems of the valves. For this purpose, the control for the valves are held in at least one common bridge which is fixedly connected to a cylinder head of the engine and the controls each operatively connected to an engine valve hydraulic cylinder with a pressurizable Spool includes. This is driven in response to electrically controllable valves in several stages continuously, the engine valves open or close depending on the control piston.

The bridge is for receiving the controls preferably T-shaped and has a central stator with a transverse head land, the stand is firmly connected via at least one screw with the cylinder head of the engine and cylindrical head or corresponding receptacles for the hydraulic cylinder or are provided for the controls.

The effect of the controls on the engine valves is such that the control pistons of the controls designed as stepped pistons or cylinder pistons hold the engine valves in a preliminary stage in the open and closed positions when the piston is in TDC and in a further subsequent stage the intake valves over the Control piston can take a maximum opening or closing position. The pressure chambers in the control piston of the controls for the same effect valves, such as inlet valves or exhaust valves are connected to each other via pressure supply lines, wherein an opening and closing of the pressure lines by means of, for example, electrically controllable solenoid valves. By means of this hydraulic actuation of the engine valves by means of the control elements, opening or closing of the engine valves is achieved in accordance with the desired control of the internal combustion engine.

The control piston is acted upon in succession via two pressure lines with pressure, wherein the control piston of the hydraulic cylinder in the pressure chamber above the control piston has opening control channels, and in a first control process, the pressure chamber via the pressure line and the subsequent control channels in the control piston are baufschlagt with a control pressure and subsequently in a second control process, the pressure lines and the subsequent control channels are acted upon with a quasi overlapping control pressure to the other pressure chamber until a discharge hole in the hydraulic cylinder is released from the control piston. The pressure chamber above the control piston is acted upon in the first control process by the pressure from the one pressure line, wherein the other pressure line is opened pressure-free and released from the control piston two mouth openings of the pressure lines via the second pressure line pressurization of the control piston until release of the discharge opening.

In particular, when the engine piston has moved sufficiently far from top dead center, oil pressure is applied to the second pressure line, wherein the engine valves can continue to open and after the release of the discharge opening in the hydraulic cylinder, the maximum stroke of the engine valve is reached, since now the oil can flow freely ,

Since the spring force increases with increasing valve lift, the piston is expediently designed as a stepped piston. The effective areas of the stepped piston are calculated according to the spring force. The stepped piston preferably has an inner transverse control channel which is connected to an annular channel, wherein the transverse control channel opens into an axial further inner control channel in the control piston and this is an upper pressure chamber trimmed. The pressure supply lines to the control piston are arranged one above the other with their junctions in the pressure chamber and with respect to the precursor of the control piston, the one pressurized pressure supply line will open into the annular space, wherein the further pressure supply line opens into a lower pressure chamber of the control piston.

The stepped piston according to the invention is hydraulically controlled by a preliminary stage via a first and a subsequent second stage via the solenoid valves in the pressure supply lines, wherein the control piston is pressurized from the precursor to a first stage adjustable, open at both pressure lines in the annular channel and the control piston is controlled such that in response to the direction of the TDC position of the engine piston, the second pressure line is acted upon by a control pressure from the solenoid valve and the control piston in the further second stage to achieve a maximum setting stroke is movable. The annular space of the stepped piston is arranged in this second stage such that a discharge opening or bore is released.

An opening of the control piston can be made gentle by adapted bevels on the piston, as well as at the end of the opening process, a bevel on the piston finish the opening process gently. Furthermore, the control piston may have a circumferentially bevelled head area.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below.

Fig. 1

eine Ansicht teilweise im Schnitt auf eine ortsfeste Brücke am Zylinderkopf mit aufgenommenen Steuerelementen der Einrichtung, die über Druckversorgungsleitungen mit Magnetventilen verbunden sind,

Fig. 2

eine Darstellung eines Steuerelements mit einem Stufenkolben in drei Stellungen,

Fig. 3

ein Ablaufdiagramm der Öffnungs- und Schließbewegungen der Motorventile mit Bezug auf die Kolbenstellung und der Stellungen der Steuerelemente,

Fig. 4, 5 und 6

Darstellungen eines Steuerelements in einer Vorstufe , einer Stufe 1 bei OT-Stellung des Motorkolbens und einer Stufe II bei voll geöffnetem Motoreinlaßventil,

Fig. 7

eine Darstellung des Gesamthubes und eines Vorhubes eines Motorventils anhand der Stellung des Steuerkolbens im Hydraulikzylinder,

Fig. 8

eine Einzelheit eines mit zwei Schrägflächen aufweisenden Steuerkolbens,

Fig. 9

eine Darstellung des gesamten Steuerzylinders mit beiden Schrägflächen,

Fig. 10

eine Darstellung des Steuerzylinders mit einem oberen und unteren Anschlag und

Fig. 11

eine Darstellung einer Brücke am Zylinderkopf gem. Fig. 1 zur Aufnahme der Hydraulikzylinder.

Show it:

Fig. 1

a view partly in section of a fixed bridge on the cylinder head with recorded controls of the device, which are connected via pressure supply lines with solenoid valves,

Fig. 2

an illustration of a control with a stepped piston in three positions,

Fig. 3

a flow chart of the opening and closing movements of the engine valves with respect to the piston position and the positions of the controls,

4, 5 and 6

Representations of a control in a pre-stage, a stage 1 with TDC position of the engine piston and a stage II with fully opened engine intake valve,

Fig. 7

a representation of the total stroke and a Vorhubes an engine valve based on the position of the control piston in the hydraulic cylinder,

Fig. 8

a detail of a control valve with two inclined surfaces control piston,

Fig. 9

a representation of the entire control cylinder with two inclined surfaces,

Fig. 10

an illustration of the control cylinder with an upper and lower stop and

Fig. 11

a representation of a bridge on the cylinder head gem. Fig. 1 for receiving the hydraulic cylinder.

In Fig. 1 is a basic design and arrangement of controls 1, 2 with control piston 8; 8a for engine valves 4, 5 of an internal combustion engine in a bridge 3, in particular for two equal-acting inlet or outlet engine valves 4, 5 with pressure supply lines 6, 7 shown. These lines 6, 7 are connected, for example, with control channels 11, 12 and 11a, 12a in the bridge 16, which open into control channels 11b, 11c, 11d, for example in the control piston 8. The pressure lines 6, 7 are the input side connected to electrically controllable solenoid valves 9, 10 for pressure control.

A control piston 1, 2 is in each case operatively connected to a valve stem 4a, 5a of the valves 4, 5, the valves 1, 2 being held in the closed position via valve springs 13, 14. As shown in more detail in Figs. 1 and 11, the control pistons 1, 2 are held in the bridge 3, wherein this is designed approximately T-shaped and comprises a central post 15 and a transverse head bar 16 by on both sides of the stator 15th the control piston 1, 2 are held. The stand 15 itself is firmly connected to the cylinder head 17 via at least one screw 18. In the head bridge 16 of the bridge 3, the control channels 11, 12 and 11a, 12a are preferably recessed, which are connected to the pressure lines 6, 7 in the cylinder head 17. The controls 1, 2 are held in corresponding cylindrical receptacles 20 in the headpiece 16 of the bridge 3.

The controls 1, 2 gem. Fig. 1 are in several successive stages V, I and II axially adjustable by hydraulic pressure control, each control 1, 2 via its control piston 8, 8a an adjusting pressure on the valve stem 4a, 5a of the valve 4, 5 exerts, causing them in a .Opening or closing position can move according to the engine piston position, as shown in more detail with reference to the diagram Fig. 3. By pressurizing the control piston 8, 8a, for example, acc. Fig. 2 and Fig.4, and 6 a precursor V (valves 4 and 5 are closed), a subsequent stage II (engine piston 21 is in TDC position) and then a stage II (valves 4 and 5 are open) driven , In the diagram of Fig. 3 is shown with dashed lines L the curve of the intake valves 1, from opening to closing and in continuous corresponding lines L1, the curve of the exhaust valves from closing to opening. The associated curve L2 shows the engine piston movement at the individual positions of the control piston 8; 8a, wherein in the TDC position of the engine piston 21, the stage I the control piston 1, 2 is assigned. The Gesamtverstellhub is indicated by H and the forward stroke with HV.

1, the control 1, 2 are approximately above the control piston 8; 8a transverse control channels 11a, 12a, which are connected to vertically extending further control channels 11, 12, which open into the pressure lines 6, 7, which can be pressure-controlled by the solenoid valves or two / two-way valves 9, 10. The control channels 11a and 12a are with control channels 11b, c and d in the control piston 8; 8a connected.

An upper pressure chamber D in the hydraulic cylinder of the control elements 1, 2 is acted upon in a first control process by the hydraulic pressure from the first pressure line 6 via the control channels 11, 11a and then via the channels 11b and 11c, the second pressure line 7 initially remains open. The engine valves 4, 5 are opened until the control piston 8; 8a, the drainage holes 25; 26 releases. This measure should be such that the engine valves 4, 5 can not touch the piston 21 in TDC position. When the engine piston 21 has moved far enough away from the TDC position, also the pressure line 7 is acted upon by oil pressure, whereby the valves 4, 5 now open further and after exposing the drain holes 25; 26 of the maximum stroke H is reached and in this position now the oil can flow. The opening and closing of the pressure lines 6,7 via the valves 9, 10. The diameter of the control piston 8; 8a should be so dimensioned that the valves 4, 5 can be opened against the force of the valve springs 13, 14.

Since the spring force increases with increasing valve lift, the control piston can preferably also be designed as a stepped piston 8a, as shown in more detail in FIGS. 2, 4, and 6 is. The mode of operation whether a stepped piston or a differently designed control piston is used, is basically the same, as far as a sequence according to the diagram acc. Fig. 3 takes place.

On the stepped piston 8a gem. 4, 5 and 6 is in the upper pressure chamber D via the control channel 11a in the bridge 16, which is connected to the pressure line 6, given oil pressure, so that the control piston 8a moves from the pre-stage V in the subsequent stage I and Stable stable in this stage I until the engine piston 21 moves down again and the solenoid valve 9 pressure on the line 7 and thus on the control channel 12a.

Now opens the control piston 8a to the maximum stroke H (diagram Fig. 3). As a stroke limiter serves on the one hand, the spring force of the valve springs 13, 14 on which the oil pressure can be matched and on the other hand, the drain hole 26, which is now released from the upper edge of the control piston 8a, so that the oil can escape freely.

The engine valve 4.5 closes in reverse order by first the solenoid valve 9, the pressure line 7 switches to passage and the oil drains and in stage II, the other solenoid valve 10 switches the pressure line 6 to passage.

The opening of the control piston 8, 8a can be effected gently by a bevelled edge 27 (FIG. 8) on the piston head 28, wherein also at the end of the opening process the bevel 27 on the piston head can end the opening process accordingly. The closing takes place in the same way at the beginning gently over the inclined edge 27 and the closing operation of the engine valve is braked again by the beveled edge.

In order for the growing spring forces to meet the increasing stroke, the control piston 8a is advantageously used, as is shown in FIGS. 4, 5 and 6 and the like. is shown. Via the upper control channel 11a of the control piston 8a in Fig. 4, the control piston 8a is initially acted upon from above in 0Druckraum D and moves a maximum until the release of the lower control channel 12a of stage 1, which is still open at this time and leak oil freely leaves. In this phase, the control piston 8a and the valve remains 4.5 until the control channel 12a stage II is either closed or even 01 promotes into the cylinder of the control piston 8a. Since the spring force increases with increasing stroke, the control piston 8a in stage II should have about twice the area or the prevailing spring force must be adapted in diameter for a constant oil pressure.

In order to obtain additional control edges for slow opening and gentle closing and to reduce the oil flow, the control piston 8 can also gem. Fig. 2 are formed. The oil penetrates into the hydraulic cylinder through the control channel 11 via a ring channel 11d in a transverse bore 11b and then into an axial bore 11c and opens the control piston 8 to the stage 1. Upon reaching the stage 1, the control channel 11a is closed and the control channel 12a opens. The oil loss is thereby minimized.

Oil pressure is supplied to the hydraulic cylinder via the control line 12a. This oil flow is also completed when reaching the maximum stroke H, at the same time opens the drain hole 26, from which then the remaining oil can escape freely.

To limit the movement of the control piston 8; 8a are stroke limiter gem. Fig. 11 is provided, which may consist of inserted screws 30,31 or lugs.

Claims (10)

1. Hydraulic control system for same valves of a diesel engine, each of which has a valve shaft and cooperates with spring means for biasing in the valve closing direction and hydraulically controllable control elements for biasing in the valve opening and/or closing direction, and the control elements are retained in a bridge connected to a cylinder head and the control elements each have a hydraulic cylinder with a pressurising control piston actively connected to the engine valves which can be displaced in several stages by means of actuatable solenoid valves depending on piston positions of the engine, characterised in that pressure chambers (D, D1) connected to pressure supply lines (6, 7) via control passages (11, 12, 11a, 12a) are provided in the control piston (8, 8a) for the same valves (4, 5) and these lines (6, 7) are opened and closed by means of the solenoid valves (9, 10), and the control pistons (8, 8a) of the control elements (1, 2) hold the engine valves (4, 5) in the closed position (S) in a preliminary stage (V) and by means of a preliminary stroke (VH) in a subsequent stage (I) when the engine piston (21) is in TDC position, and in another stage (II), the engine valves (4, 5) can be moved by the control pistons (8, 8a) into a maximum open position.
2. System as claimed in claim 1, characterised in that the control passages (11, 12, 11a, 12a) open above the pressure chamber (D) of the control piston (8, 8a) and, in a first control procedure, the pressure chamber (D) can be pressurised via the pressure line (6) and the control passages (11, 11a; 11b, 11c) can be pressurised with a control pressure, after which, in a second control procedure, the pressure line (7) and the control passages (12, 12a; 11b, 11c) can be pressurised with a superimposing control pressure to the other bottom pressure chamber (D1) until an outlet bore (25; 26) in the hydraulic cylinder can be released by the control piston (8a; 8).
3. System as claimed in claim 1 or 2, characterised in that the pressure chamber (D) can be pressurised by the pressure on the pressure line (6) during the first control procedure, whilst the other pressure line (7) is pressure-free and open, and when both opening orifices of the pressure lines (6, 7) are released by the control piston (8a; 8), pressure is applied to the control piston (8a; 8) via the second pressure line (7) until the outlet orifices (26:25) are released.
4. System as claimed in one of claims 1 to 3, characterised in that the control piston is provided in the form of a stepped piston (8) and has an annular passage (11d) connected to the transversely extending control passage (11b), and the control passage (11b) is connected to the other axial control passage (11c) which faces a pressure chamber (D).
5. System as claimed in one of claims 1 to 4, characterised in that the pressure supply lines (6, 7) are disposed with their inlet openings to the pressure chamber (D) one above the other and - with respect to the preliminary stage (V) - one supply line supplied with pressure opens into the annular chamber (11d), whilst the other pressure supply line opens into the bottom pressure chamber (D1) of the control piston (8).
6. System as claimed in one of claims 1 to 5, characterised in that the control piston (8) supplied with pressure via the pressure line (6) is designed so as to be displaceable from the preliminary stage (V) into stage (I) in which both pressure lines (6, 7) open into the annular passage (11d), and the control piston (8) can be activated so that the pressure line (7) can be pressurised with a control pressure by the solenoid valve (9) depending on the position of the engine piston (21) in the TDC direction and the control piston (8) can be moved into stage II in order to effect a maximum displacement stroke.
7. System as claimed in one of claims 1 to 6, characterised in that the annular passage (11d) of the control piston (8) is disposed so that an outlet orifice (26) is released in stage (II).
8. System as claimed in one of claims 1 to 7, characterised in that in stage (II), the solenoid valve (9) of the pressure line (7) can be switched to open mode first of all, after which the other solenoid valve (10) of the pressure line (6) can be switched off, as a result of which oil flows out of the pressure chamber.
9. System as claimed in one of claims 1 to 8, characterised in that a stepped piston of the control piston (8; 8a) has an oblique head region (27) around the peripheral face.
10. System as claimed in one of claims 1 to 9, characterised in that the bridge (3) is of a T-shaped design and incorporates a central mount (15) with a transversely extending top web (16) and the mount (15) is connected to the cylinder head (17) by means of at least one screw means (18) and the control elements (1, 2) are retained in the top web (16) in recesses (20).

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