WO1997039224A1

WO1997039224A1 - Device for changing opening and closing times of gas exchange valves in an internal combustion engine

Info

Publication number: WO1997039224A1
Application number: PCT/EP1996/005147
Authority: WO
Inventors: Andreas Strauss; Jochen Auchter; Rainer Ottersbach; Mike Kohrs
Original assignee: INA Wälzlager Schaeffler oHG
Priority date: 1996-04-12
Filing date: 1996-11-22
Publication date: 1997-10-23
Also published as: DE19681401D2; DE19614558A1

Abstract

A device (1) for changing the opening and closing times of gas exchange valves in an internal combustion engine has coupling means (15) which create an interlocking link between their driving unit (3) and the output unit (9) when their regulating piston (6) is in a limit position, and clearance regulating means (17) which by turning allow the coupling position of the coupling means (15) to be precisely placed with respect to the limit position of the regulating piston (6) during final assembly of the device (1).

Description

Name of the invention

Device for changing the opening and closing times of gas exchange valves of an internal combustion engine

description

Field of the Invention

The invention relates to a device for changing the opening and closing times of gas exchange valves of an internal combustion engine according to the precharacterizing features of claim 1.

Background of the Invention

Such a device is previously known from DE-PS 29 09 803. After starting the internal combustion engine, the problem arises in such a device that the respective adjusting piston rushes to a maximum adjusting position at high speed and strikes there several times with considerable noise emission. This is due to the fact that after the internal combustion engine has been taken out of operation, the hydraulic medium in the device gradually escapes from it and the adjusting piston is therefore no longer sufficiently hydraulically clamped, with a certain residual volume of hydraulic medium generally remaining. Caused by the rotational nonuniformity of the camshaft, after the internal combustion engine has been re-fired, the adjusting piston, since it is no longer hydraulically clamped, is moved into an end position under the considerable noise development mentioned. This state is in the period between the firing of the internal combustion engine 7/39224 2 PC17EP96 / 05147

and filling the pressure chambers, d. H. a few seconds after the engine starts.

Object of the invention

The invention is therefore based on the object of presenting a device of the abovementioned type in which the disadvantages indicated have been eliminated and in particular by simple means, ie. H. with little design effort the displayed start rattling and a swinging of the adjustment angle between the camshaft and crankshaft is avoided while at the same time creating an inexpensive possibility of adjusting the play of its components which are in rotary engagement with one another.

Summary of the invention

According to the invention, this problem is solved according to the features of the characterizing part of claim 1, expedient developments of the invention being the subject of subclaims 2 to 17.

Due to the means according to the invention shown in claim 1, on the one hand, the rattling noises occurring in the prior art due to high-frequency striking of the adjusting piston at its one end position can no longer be expected. The adjusting piston is preferably held in one of its maximum possible stop positions ("late" or "early" opening of the gas exchange valves concerned). Due to the play adjusting means applied at the same time as the other, it is extremely successful to set the coupling position of the coupling means with respect to the desired stop position of the adjusting piston. Without this play setting option, in order to create a small torsional play of the device parts in the locked state, the toothed sections which are in engagement with one another and the coupling means would have to be manufactured extremely precisely in order to eliminate any overlapping tolerances. This possibility of adjusting the rotational position of the coupling means in relation to the stop position of the adjusting piston Before the internal combustion engine is started up for the first time, it is possible to compensate for any existing component tolerances and precisely define the coupling position of the adjusting piston.

In an expedient development of the invention, the coupling means is designed as a hydraulically displaceable slide which can optionally be coupled to the exhaust or drive unit when the pressure on hydraulic means decreases. The play setting means are to be connected to the slide in a rotationally fixed manner via an axial guide. These are for example after the game setting u. a. connected to the coupling means via a welded connection or caulking and can be produced as a sheet metal ring enclosing the coupling means. A play setting between the coupling means and the output or drive element can also take place via communicating screw means, wedges and other machine elements, it is only important at this point that the components just mentioned are rotationally fixed to one another during operation of the device.

A coupling of the coupling means is preferably provided with the output unit. Immediately before the internal combustion engine is taken out of operation, the pressure chamber of the device is filled with hydraulic medium which faces away from the desired starting position of the adjusting piston, so that the adjusting piston is displaced into its desired starting position via the hydraulic medium. Since, according to a first proposal, the pressure chamber of the coupling means is identical to that of the adjusting piston, in this state there is not sufficient hydraulic medium pressure in front of the coupling means and the coupling means also moves (optionally), via its force, into its coupling position via the force of a spring means, which was previously adjustable by rotating the play setting means with respect to the drive unit.

In an expedient development of the invention, the slide is designed, for example, as a concentric ring enclosing the output unit, so that it has a sufficiently large piston area for its hydraulic displacement has movement. At this point, however, it is also conceivable for at least one "satellite-like" axially parallel slide in one of the pressure chambers. It is also provided that the slide is moved into its coupling or decoupling position, for example via valve devices, by means of completely separate actuating means.

In order to prevent an undesired escape of hydraulic fluid from the pressure chamber in front of the slide or its separate pressure chamber according to a further subclaim, the slide is provided radially on the inside and outside with corresponding sealing means, such as sealing rings, which are positioned in complementary cutouts can.

It is advantageous if the slide is displaced into its decoupling position via the hydraulic medium pressure, which is present anyway in one of the pressure chambers. According to one embodiment of the invention, the pressure chamber of the slide should be identical to the pressure chamber which faces the device on the adjusting piston side and, according to a further development of the invention, the slide should be hydraulically coupled to the pressure chamber facing away from the device via a path. The latter measure proves to be particularly useful if the adjusting piston is said to have assumed a starting position that is remote from the device, i. H. axially facing outwards and at the same time is to be held in this position by the coupling means. For example, such a configuration is necessary if the abovementioned stop position identifies the early position of the adjusting piston (for adjusting devices on the outlet side) and, for reasons of installation space, a compression spring acting on the adjusting piston in the opposite direction to the rotational nonuniformities of the camshaft (acting in the "early" direction) on the device side Pressure chamber must be installed.

Generally speaking, the stop position of the adjusting piston in the device is thus dependent on the application of the respective device (intake or exhaust camshaft or common assignment) and the arrangement of the serrated sections of the adjusting piston and the input and output unit are mutually dependent.

At the same time, as already mentioned, the adjusting piston is additionally to be sprung in an adjusting direction by the force of a compression spring or a similar spring means, this adjusting direction is, for example, that which is directed against the drag torque of the camshaft acting in the "late" direction . However, it can also run in the direction of the drag moments of the camshaft.

The specified separate path to a pressure chamber in front of the coupling means is, according to a concretization of the invention, arranged radially outside of an annular part radially enclosing the adjusting piston and is designed, for example, as an annular space. However, it is also conceivable to design this path as a channel extending within the drive unit.

The clearance adjustment means designed as a ring can be provided on the end face with radially inward-facing approaches, through which approaches the coupling means are simultaneously given stops for its displacement movement. In a further development of the invention, the ring can also be designed such that it limits the device radially outward, as a quasi housing part, in the axial extension of the drive unit. The slide should run as far as possible completely in a hole in the ring. Alternatively, it is envisaged to install the ring with a large part of its outer surface in a corresponding bore of the drive unit and to weld it there on the end face after the play has been set.

A solution is also conceivable and envisaged in which a plurality of coupling stages are realized via the coupling means via the adjusting range of the adjusting piston, so that a mechanical holding of the adjusting piston is produced via these coupling stages. Any servo means, but preferably hydraulic means, is intended as a means for adjusting the adjusting piston and the coupling means. In addition, two basic coupling mechanisms are provided. On The first, preferred mechanism provides for the adjusting piston to be hydraulically displaced into its starting position (stop position) immediately before the internal combustion engine is switched off, and for there to be an immediate locking via the coupling means. According to an alternative proposal, it may be also conceivable for the coupling combustion engine to produce only after Wiederbefeuern the focal _¬ by the adjusting erreich¬ in his first ten late position which he already due to the lack Hydraulikmittel¬ filling-an award by the Drehungieichförmigkeit the camshaft ¬ want to couple and hold there until the device is again sufficiently filled with hydraulic fluid.

Brief description of the drawing

The invention is expediently shown in the drawing. Show it:

1 shows a longitudinal section through a device according to the invention with decoupled coupling means;

Figure 2 shows a device according to Figure 1 in mirror-image half section, but with a coupled coupling means and adjusting piston in a preferred coupling position;

Figure 3 is a partial view of a device similar to Figure 1 with a special design of the game adjusting means and

Figure 4 shows a device similar to that shown in Figure 1.

Detailed description of the drawing

FIG. 1 shows a device 1 for changing the opening and closing times of gas exchange valves of an internal combustion engine, the structure and mode of operation of which are known in principle to those skilled in the art. The device 1 exists from a drive wheel 2, which is fastened here on a hollow cylindrical drive unit 3. The drive unit 3 has a radially outward toothing (helical toothing) 4 which interacts with an internal toothed section 5 of a hydraulically displaceable adjusting piston 6. The adjusting piston 6 in turn has an external, helically toothed section 7 which engages with a toothing 8 of an output unit 9. The output unit 9 is in turn non-rotatably connected to a camshaft, not shown.

The adjusting piston 6 delimits with its two end faces 10, 1 1 pressure chambers 12, 13 for hydraulic means. A feed line from the hydraulic means into the pressure chamber 12, for example via a path 14, causes the adjusting piston 6 to be displaced into the stop position shown in FIG. 1. This hydraulic displacement of the adjusting piston 6 in the axial direction leads via the toothing or sections 4, 5, 7, 8 to a relative rotation of the drive wheel 2 to the camshaft, not shown.

It can also be seen from FIG. 1 that an annular coupling means (slide) 15 adjoins the pressure chamber 12. This coupling means 15 is connected radially on the outside via an axial guide 16 to a play adjusting means 17 to be explained later. The play setting means 1 7 in turn experiences a torsion-proof connection with the drive means 3 (here also formed as a housing), for example via a weld 18.

In order to prevent an undesired escape of hydraulic medium from the pressure chamber 12, which is adjacent to the coupling means 15, this coupling means 15 has sealing means 19 which are designed radially on the inside and outside as sealing rings and which are arranged in a sealing manner with respect to the opposite parts 9, 17. At the same time, the coupling means 15 in the device direction, ie here in the direction of the pressure chamber 12, is spring-loaded via the force of a spring means 20, which surrounds the output unit 9 in a ring, such as a helical spring. Furthermore, the slide has an extension 21 axially on the inside, which in a recess 22 of a radial projection 23 of the output unit 9 is opposite to one another in a rotational position from the drive unit 3 to the output unit 9.

If the internal combustion engine is now switched off and the adjusting piston 6 is at this moment, for example in the stop position shown in FIG. 1, the pressure chamber 13 is filled with hydraulic medium and the pressure chamber 12 is relieved of this. As a result, the adjusting piston 6 is moved from the stop position shown in FIG. 1 to the stop position shown in FIG. Since the coupling means 15 is now also relieved of the pressure of hydraulic means from the pressure chamber 12, its spring 20 displaces it axially along the axial guide 16 in the direction of the adjusting piston 6. Extension 21 of the coupling means 15 now slides into the aligned recess 22 of the output unit 9. Through this coupling process, drive unit 3 and output unit 9 are positively connected to one another until a sufficiently high pressure of hydraulic medium has in turn developed in the pressure chamber 12. However, due to the fact that the device 1 is idling on hydraulic means after it has been deactivated, this is only delayed after the internal combustion engine has been fired again. This coupling prevents the high-frequency striking of the adjusting piston 6, which is disadvantageously known from the prior art, to its late stop position (for example the position shown in FIG. 2), caused by the alternating torques of the camshaft acting in the "late" direction. The stop position of the adjusting piston 6 shown in FIG. 2 is thus also its preferred starting position ("late" opening and closing of the intake valves when the device 1 is applied to an intake camshaft). If the achieved coupling position of the adjusting piston 6 is now to be exited, for example when the internal combustion engine is operated under partial or full load, the pressure chamber 12 is filled with hydraulic medium. The adjusting piston 6 executes an axial movement in the direction remote from the device and at the same time the pressure of hydraulic means also shifts the coupling means 15 axially outwards. The previously described anti-rotation device is thus canceled. About the game setting means 1 7:

As can be seen from FIG. 1 and also from the other figures, the play setting means 17 is connected to the coupling means 15 via an axial guide 16. After the aforementioned components of the device 1 have been assembled, the adjusting piston 6 is brought into the stop position shown in FIGS. 2 and 4 by rotating the drive wheel 2 to the camshaft (not shown). This stop position represents the desired coupling position. In this case, a first stop is created in one direction of rotation, for example by abutment of the adjusting piston 6 (see FIG. 2) against a radially inwardly facing extension 24 of the play adjusting means 17 and a further stop in the further direction of rotation a surface of the recess 22 on which the projection 21 rests. This location assignment can, however, only be manufactured in such a way that the position is precisely aligned such that in the stop position just described, shoulder 21 aligns with recess 22. It is therefore proposed according to the invention that a fine adjustment of a position assignment of the coupling position is created via the play setting means 17. Overlapping gear errors also influence each other. the exact position assignment from attachment 21 to recess 22. By turning the play adjusting means 1 7 directly before its rotationally fixed attachment to the drive means 3, the disadvantageous tolerances that have occurred up to that point are thus compensated for. After the game has been set, it is provided to connect the game setting means 17 to the drive unit 3, for example via the weld 18.

Figures 1 and 2 also disclose that the path 14 opens into the piston 15 limited by the slide 15 and adjusting piston 6 pressure chamber 12, d. H. a filling of hydraulic means causes a movement of the adjusting piston 6 and coupling means 15 at the same time axially away from one another.

In the embodiment shown in FIGS. 1 to 3, the projection 24 of the play setting means 17 also serves as a travel limitation for the coupling means 15. At the same time, FIGS. 1 and 2 show that another Approach 25 at the further end of the play setting means 1 7 the axial movement of this can be limited in the additional direction.

Figure 3 shows an alternative embodiment and arrangement of the game setting means 17 according to the aforementioned figures. In this case, the play setting means 1 7 has a diameter reduction 26 on the device side, by means of which it is fastened in a rotationally fixed manner to an inner casing 27 of the drive unit 3 after the play has been set. At the same time, it can be seen from FIGS. 3 and 4 that the adjusting piston 6 is sprung in a direction of displacement by the force of a compression spring 28. This compression spring 28 is intended to displace the adjusting piston 6 against the alternating moments of the camshaft acting in the "late" direction. Thus, the adjusting piston 6 is shown in Figures 3 and 4, for example, in its "early" stop position. This stop position can be the desired starting position, for example, when a device 1 is applied to an exhaust camshaft, since only a slight valve overlap and thus low residual gas components in the cylinder can be expected by shifting the opening times of the exhaust valves in the direction of early opening and closing .

As the person skilled in the art can also see from FIG. 4, a ring part 29 is applied radially between the inner jacket 27 of the drive unit 3 and the adjusting piston 6. The adjusting piston 6 runs sealingly within the ring part 29. Between the ring part 29 and the inner jacket 27, a path 30 designed as an annular space is arranged to a separate pressure chamber 31 for hydraulic medium. This separate pressure chamber 31 is connected via path 30 to the pressure chamber 11 and lies directly in front of the coupling means 15. For the stop and coupling position of the adjusting piston 6 shown and desired in FIG. 4, the pressure chamber 11 becomes hydraulic means relieved, the pressure chamber 12 being loaded so that the coupling means 15 can be moved into the coupling position shown. In turn, drive unit 3 and output unit 9 are positively coupled to one another after the internal combustion engine has been shut down. Only after it is possible in the pressure chamber 1 1 after the refiring To build up an adequate pressure of hydraulic medium in the internal combustion engine, the coupling just described can be released. This embodiment is particularly advantageous when it is desirable to hold the adjusting piston 6 in its external stop position shown in FIG. 4 for the early position and there is insufficient space in the pressure chamber 11 for an arrangement of this compression spring 28 (with a reversal of the toothing and the stop position of the adjusting piston 6).

It can also be seen from FIGS. 3 and 4 that the play setting means 1 7, in the axial extension of the drive unit 2, performs its housing function at least with partial sections and thus limits the device 1 radially outward in the area of the coupling means 1 5.

LIST OF REFERENCE NUMBERS

1 device 17 game setting means

2 drive wheel 18 weld

3 Drive unit 19 sealant

4 teeth 20 spring

5 Section 21 Approach

6 adjusting pistons 22 recess

7 Section 23 Radial Approach

8 teeth 24 approach

9 output unit 25 approach

10 end face 26 diameter reduction

1 1 face 27 inner jacket

12 Pressure chamber 28 compression spring, spring means

13 pressure chamber 29 ring part

14 path 30 path

15 coupling means, slide 31 pressure chamber

16 axial guidance

Claims

claims

1. Device (1) for changing the opening and closing times of gas exchange valves of an internal combustion engine, which are arranged within a control drive of at least one inlet or exhaust camshaft mounted in a cylinder head, preferably on a drive wheel (2) which is in drive connection with the camshaft The device (1) has an adjusting piston (6) which is axially displaceable by hydraulic means and which is provided with two, preferably counter-rotating, helically toothed sections (5, 7), of which the first section (5) has one Complementary toothing (4) of a drive unit (3) non-rotatably connected to the drive wheel (2) and the second section (7) communicates with complementary toothing (8) of an output unit (9) non-rotatably connected to the camshaft and which adjusting piston (6) is connected at least one of its end faces (10, 1 1) delimits a pressure chamber (12, 13) for the hydraulic medium, characterized in that ¬ draws

that at least one coupling means (15) is provided in the device (1), by means of which the input and output unit (3, 9) can be connected to one another in a rotationally fixed manner in one or more rotational position (s), the coupling means ( 15) or a device part (17), which communicates with this device in a rotationally fixed manner, via which a defined position assignment of a coupling position of the coupling means (15) with respect to the rotational position of the input and output unit (3, 9) is related can be produced.

2. Device according to claim 1, characterized in that a coupling via the coupling means (15) in a rotational position of the input and output unit (3, 9) to each other is made, in which the adjusting piston (6) one of its maximum stop positions in the device (1) has taken. 3. Device according to claim 1, characterized in

that a slide which is hydraulically displaceable axially in the direction remote from the device is positioned as a coupling means (15) in one of the pressure chambers (12 or 13) which can be acted upon by hydraulic means or in an adjoining area,

- That the exhaust or drive unit (9 o. 3) or the slide (15) has at least one in the direction of the other component (15, 9 o. 3) extending recess (22) which forms a complementary approach ( 23) on the other component (1 5, 9 o.

3) aligned in a rotational position of the units (3, 9),

- That the slide (15) is axially displaceable in this rotational position in the direction of the device (1) with decreasing pressure of hydraulic means, that approach and recess (21, 22) are positively coupled with each other and

- That the slide (15) radially outside (when coupled to the drive unit (3)) or radially inside (when coupled to the output unit (9)) via a

Axial guide (16) is connected to the play setting means (1 7).

4. The device according to claim 3, characterized in that the Spielein¬ adjusting means (1 7) as the coupling means (1 5) is formed radially on the outside at least at partial sections surrounding ring, which for the operation of the device (1) after Clearance adjustment, can be connected in a rotationally fixed manner to the drive unit (3).

5. The device according to claim 4, characterized in that the connection of the play adjusting means (1 7) with the drive unit (3) via a weld

(18) or caulking is produced.

6. The device according to claim 3, characterized in that the slide (15) as a radially inside the drive unit (3) and the play setting means (1 7) extending concentric ring is made, which encloses the output unit and preferably in the coupling direction via a spring means (20th ) how at least one compression spring can be moved.

7. The device according to claim 6, characterized in that the slide (15) radially outside and inside via sealing means (19) such as sealing rings against its adjacent component (1 7, 9) is applied.

8. The device according to claim 3, characterized in that in the Vor¬ direction (1) a common path (14 or 30) for the hydraulic displacement of the slide (15) in the direction remote from the device (decoupling position) and for displacement of the adjusting piston (6 ) is created.

9. The device according to claim 8, characterized in that the path (14) in the axially delimited by the slide (1 5) and adjusting piston (6) pressure chamber (12) opens (Figures 1, 2).

10. The device according to claim 8, characterized in that the path (30) simultaneously in the pressure chamber (15) facing away from the slide (1 1) in front of the adjusting piston (6) and in a separate pressure chamber (31) in front of the slide (1 5 ) leads (Figure 4).

1 1. Apparatus according to claim 10, characterized in that the pressure chambers (1 1, 12) are delimited radially on the outside by a separate ring part (29) on which the adjusting piston (6) runs, between the ring part (29) and the drive unit (3) the path (30), starting from the pressure chamber (1 3), is arranged to the pressure chamber (31).

12. The apparatus according to claim 1 1, characterized in that the path (30) immediately before the pressure chamber (31) is made as an annular space.

13. The apparatus according to claim 4, characterized in that an axial path limitation of the slide (15) in at least one of its directions of movement via an at least indirectly connected to the ring (1 7) or extending in one piece therefrom, pointing radially inward Approach (24, 25) is created.

14. The apparatus according to claim 1, characterized in that the Verstell¬ piston (6) in a displacement direction via the force of a separate Feder¬ means (28) such as a compression spring (Figures 3, 4).

15. The apparatus according to claim 3, characterized in that the Verstell¬ area of the slide (15) extends at least largely axially outside the Ver¬ storage area of the adjusting piston (6), wherein the Spiel¬ setting means (1 7) the device (1) bounded radially outwards at least in the area of the slide (15) (FIGS. 3, 4).

16. The apparatus according to claim 3 or 1 5, characterized in that the play adjusting means (17) via a diameter reduction (26) on an inner jacket (27) of the drive unit (3) (Figures 3, 4).

1 7. Apparatus according to claim 16, characterized in that the diameter reduction (26) is simultaneously made as a shoulder (24) for limiting the displacement of the adjusting piston (6) in its one direction of displacement (coupling direction) (Figures 3, 4).