CN1742152A - Fully variable mechanical valve drive mechanism for a piston-type internal combustion engine comprising adjustable valve play compensation - Google Patents

Abstract

The invention relates to a variably adjustable valve drive mechanism for at least one gas exchange valve (1) of a piston engine, especially a reciprocating internal combustion engine, said gas exchange valve (1) comprising a closing spring (2). The inventive valve drive mechanism is provided with a driving means (14) that acts upon a stroke-transmitting means (4) which is formed by several cooperating partial elements, affects the gas exchange valve (1) counter to the force of the closing spring (2), comprises an adjustable control element (12), and is effectively connected to a drag lever (5). The free end of said drag lever (5) rests on the shaft end (3) of the gas exchange valve (1) while the other end thereof is mounted on a play-compensating element (6) which forms a pivot bearing (6.1) and is disposed on the cylinder head. Said other end of the drag lever (5) is connected to a means (20) for adjusting the pivot bearing (9) relative to the stroke-transmitting means (4).

Description

Fully variable mechanical valve drive for piston internal combustion engines with adjustable valve lash compensation

technical field

The mechanical valve drive has a camshaft, wherein the stroke determined by the geometry of the cam is transmitted via a drawbar to the intake/exhaust valve to be actuated. By disposing an adjustable stroke transmission device between the cam and the drawbar, the mechanical valve drive mechanism can be designed to be fully variable.

Background technique

Fully variable mechanical valve drives for piston internal combustion engines are disclosed, for example, in DE 100 06 018A or WO 02/053881A. In this valve drive mechanism, a stroke transmission device formed by a plurality of cooperating sub-elements is arranged between the drive device in the form of a cam, for example a camshaft, and the intake/exhaust valve to be manipulated. The device enables the full stroke defined by the cam profile to be varied between zero stroke and full stroke by means of a correspondingly configured adjustable control element in accordance with operationally relevant regulations.

The stroke transfer device acts on a draw rod, which is supported with its free end on the rod of the intake/exhaust valve to be actuated and rests with its other end on a preferably movable shaft arranged on the cylinder head forming a swivel bearing. Hydraulically operated backlash compensation element.

Contents of the invention

The invention is based on the problem of improving such a valve drive with a plurality of subelements in such a way that unavoidable manufacturing tolerances which adversely affect the timing function can be compensated for.

According to the invention, this problem is solved using a variable adjustable valve drive having the features stated in claim 1 . By connecting the play compensating element to the adjusting device, it is possible to change the geometric assignment of the drawbar relative to the stroke transmission device by displacing the swivel bearing of the drawbar, so that excellent kinematics can be achieved.

In an advantageous embodiment of the invention it is provided that the device for adjustment via the eccentric sleeve connected to the cylinder head is formed as a receptacle for the play compensating element. In this solution, it is advantageously used that the play compensating element is usually inserted into a corresponding piston skirt inner edge bore in the cylinder head.

The adjustment for compensating production-related dimensional deviations can now be realized according to an embodiment of the invention in that the eccentric sleeve as a receiving device for the play compensating element has different eccentricities in order to correspond to the detected dimensional deviations. Insert an eccentric sleeve with a "fit" eccentricity.

In a further configuration of the invention it is provided that the eccentric sleeve is configured to be rotatable. In this case, an eccentric sleeve is provided with an eccentricity which corresponds to the maximum production-related dimensional deviation to be predicted. By twisting the eccentric sleeve in the cylinder head, a stepless adjustment of the axis of rotation of the pivoting element relative to the fixed axis of rotation of the guide element can be achieved.

In both cases, means are provided for fastening the eccentric sleeve on the cylinder head. This means can be formed, for example, by counter straps on an eccentric sleeve which engages in the cylinder head. It is also possible to provide an eccentric sleeve with an axial displacement groove, into which steel balls are pressed after adjustment, so that the eccentric sleeve is fixed in the event of deformation of the base material of the cylinder head.

Other features and arrangements of the invention are described in the following description and appended claims.

Description of drawings

Figure 1 is a mechanical valve drive mechanism;

Fig. 2 is a partial cross-sectional view of the configuration of the gap compensation element;

Figure 3 is a top view of the arrangement according to Figure 2; and

Figure 4 is a perspective view of the play compensating element and the eccentric sleeve.

Detailed ways

The invention is explained in more detail on the basis of schematic diagrams of exemplary embodiments.

The valve drive mechanism shown schematically in FIG. 1 is mainly composed of an intake/exhaust valve 1 held in a closed position by a valve spring 2 . To the free end 3 of the valve stem of the intake/exhaust valve 1 is assigned a stroke transmission device 4 formed by a plurality of cooperating partial elements adjustable in their position relative to each other, which stroke transmission device 4 acts on the drawbar 5.

According to the provisions of the present invention, all that act between the drive device 14 (the cam of the camshaft, that is to say the electric or hydraulic actuator) and the traction rod 5 acting directly on the intake/exhaust valve 1 are operatively connected to each other. All sub-components shall be regarded as "stroke transmission device". By adjusting the sub-elements to each other, their mechanical-geometric interaction can be changed, so that the actual stroke acting on the intake/exhaust valve 1 via the drawbar 5 is at "zero", with the stroke specified, for example, fixed by the cam. Variable adjustment between "Stroke" and "Full Stroke".

In the case of the exemplary embodiment shown here, mainly a guide element 11 with a control curve 12 and a pivot element 8 are provided as subelements of the stroke transmission device 4 .

The drawbar 5 is mounted on the cylinder head or the engine block via play compensating elements 6 for valve play compensation and rests with its free end 7 on the rod end 3 of the intake/exhaust valve 1 . The support of the drawbar 5 on the play compensation element 6 simultaneously forms the swivel bearing 6 . 1 for the drawbar 5 .

On the drawbar 5 , between the swivel bearing 6 . 1 and the backing plate on the rod end 3 of the inlet/exhaust valve 1 , a swivel element 8 is arranged so as to be reciprocating about a swivel axis 9 . The swivel element 8 has a guide roller 10 at its free end facing away from the swivel axis 9 .

Furthermore, a guide element 11 with a control curve 12 for the guide roller 10 is also assigned to the swivel element 8 . The guide element 11 is adjustable relative to the intake/exhaust valve 1 on the cylinder head or the engine block about a fixed axis of rotation in the direction of the double arrow 13, so that, as described in more detail below, for the guide The rolling of the roller 10 can define different rolling areas.

Furthermore, the swivel element 8 is provided with a pressure roller 8.1 between the guide roller 10 and the swivel axis 9, on which a drive means with a control profile 15 in the form of a cam 14 of a camshaft acts. The pivoting element 8 is pressed against the control contour 15 of the cam 14 by means of a return spring 16 , for example in the form of a coil spring or a bending spring as shown.

The advantage of this form of return spring is that the spring elements can be distributed in a space-saving manner in the very limited construction space in the area between the camshaft and the intake/exhaust valves, which enables almost constant return spring forces The lower accommodates the proportionally greater stroke of the swivel element 8 .

The intake/exhaust valves are shown in the closed position. When the cam is rotated in the direction of arrow 17 , the pivoting element 8 is pivoted about its axis of rotation 9 . Since the guide roller 10 rolls on the control contour 12, it is possible, with a corresponding positioning of the guide element 11, to follow the guide roller 10 only following the control contour 12, so that correspondingly the force between the cam 14 and the pressure roller 8.1 The role of the drawbar 5 supported on the slewing bearing 6.1 is also hinged downward toward the arrow 17 in the same direction, and in this case, the intake/exhaust valve 1 is opened against the force of the valve spring 2.

The control contour 12 of the guide element 11 now has a first contour region I, which is formed as a circular track, the center point of which is in the closed inlet/row with the axis of rotation of the guide element 11 and the axis of revolution of the swivel element 8. The valve case coincides. This achieves that, with the rotation of the cam 14 , although the pivoting element can pivot back and forth, no force action on the drawbar 5 and thus no opening stroke of the valve 1 takes place. Only when the guide element 11 is turned in the direction of the cam 14 does the guide roller 10 roll through the region II of the control profile, which has a smaller radius of curvature and therefore also has another track center point, so that Correspondingly, the draw bar 5 is pressed in the open position by the swivel element 8 . This region II of the control contour 12 is formed corresponding to the requirements for the stroke kinematics of the intake/exhaust valve 1 . Depending on the positioning of the guide element 11 , it is now possible to adjust from a zero stroke to a full stroke by operating any reduced stroke width.

By using the hydraulic play compensating element 6 constructed in a conventional manner, the play between the parts of the stroke transmission device 4 caused by temperature-related length changes and/or wear during operation is compensated, so that between the valve spring 2 and Under the combined action of the return spring 16, not only the pressure roller 8.1 but also the guide roller 10 rolls on its control contour without play.

The axis of rotation of the guide element 11 and the axis of rotation 9 of the pivot element 8 must ideally coincide in the case of a closed intake/exhaust valve. Since the axis of rotation of the guide element 11 is fixed on the cylinder head, the position of the axis of rotation 9 of the rotary element 8 will deviate from the ideal position due to manufacturing tolerances twisted together. As shown in FIG. The swivel bearing 6 . 1 thus serves as a means for adjusting the swivel axis 9 of the swivel element 8 relative to the swivel axis of the guide element 11 . In the case of the exemplary embodiment shown here, a bore 18 is provided in the cylinder head Z, into which a cylindrical sleeve with an eccentric bore 19 , the so-called eccentric sleeve 20 , is inserted. The play compensating element 6 is inserted into the eccentric bore 19 of the eccentric sleeve 20 .

FIG. 3 shows a plan view of the arrangement according to FIG. 2 and shows the eccentricity e of the axis 6.2 of the play compensating element 6 with respect to the axis 20.1 of the eccentric sleeve 20 . The drawbar 5 is arranged with its spherical crown recess 5.1 at the corresponding spherically formed end of the play compensating element 6 which forms the swivel bearing 6.1. FIG. 2 is on the same plane of illustration as that shown in FIG. 1 .

The play compensating element 6 and thus also the eccentric sleeve 20 is in this embodiment inclined at an angle to the displacement axis 1.1 of the intake/exhaust valve 1 in the swivel bearing 6.1 for reasons of advantageous force transmission. alignment. If now, as shown in FIG. 3 , the eccentric sleeve 20 is turned in the direction of the arrow 21 from the initial position shown in FIG. The defined bearing midpoint 6.3 (Fig. 2) is moved to the corresponding obliquely aligned circular orbit, so that the bearing midpoint 6.3 is directed to the illustration in Fig. 1, not only in the X direction of the coordinate system shown in Fig. 1 is transverse, It is also transverse in the Y direction, ie in the direction of the movement axis 1.1 of the intake/exhaust valve 1 . In order to adjust the axis of rotation 9 relative to the axis of rotation of the guide element 11 , it is only necessary here that both axes have practically the same transverse distance from the axis of movement 1 . 1 of the intake/exhaust valve 1 . The different height positions in the Y direction do not matter. It is also irrelevant that in the case of torsion the bearing center point 6.3 is also displaced in the Z direction (see FIG. 3 ). Thus only a parallel displacement of the stroke transmission device 4 overall relative to the intake/exhaust valve 1 and the cam 14 and the guide element 11 takes place.

FIG. 4 shows a perspective view of the eccentric sleeve 20 with the inserted play compensating element 6 . It can be seen from the figure that the eccentric sleeve 20 has a radial bore 21 which is assigned an oil distribution groove 22 on the outer surface.

It can be seen from the cross-sectional view in Fig. 2 that the pressure oil passage 23 in the cylinder head is cut through the inner edge hole 18 of the piston skirt, so that under the corresponding positioning of the hole 21 and the oil distribution groove 22, a gap with the oil distribution groove 22 is generated. The connection of the compensating element 6 , and thus via the movable part of the play compensating element, enables the stroke transmission device 4 to be held without play by a corresponding pressurization of the drawbar 5 . The play compensating element 6 and the eccentric sleeve 20 are respectively inserted gas-tight and liquid-tight here.

Instead of only the above-mentioned rotatable configuration of the eccentric sleeve, it is also possible to provide various assorted eccentric sleeves which, for example, have eccentricities of 0.02 mm, 0.04 mm and 0.06 mm according to the class. According to the determined dimensional deviation, the corresponding selected eccentric sleeve is inserted. This can be done, for example, in the form shown in FIG. 3 by inserting the eccentricity steps in the plane defined by the axis 6 . 2 of the play compensating element 6 and the movement axis 1 . The intermediate stage can be adjusted at an angle to the above-mentioned plane, for example by inserting the assorted eccentric sleeve.

Not only the twistable implementation, but also the fixed insertion implementation is fixed in the piston skirt inner edge hole 18 respectively, this is carried out by frictional connection, clamping action, corresponding strap or by the locking ball 24 pressed in, As shown in Figure 3.

Claims (8)

1. one kind supplies reciprocating-piston engine, particularly at least one on the internal-combustion reciprocating-pisto is provided with the variable adjustable valve actuating mechanism of import/exhaust door (1) usefulness of return spring (2), this valve actuating mechanism has drive unit (14), this drive unit (14) acts on the stroke transfer unit (4), the masterpiece that this stroke transfer unit (4) overcomes return spring (2) is used for import/exhaust door (1), and form by a plurality of coefficient subelements, this drive unit (14) has adjustable control element (12) and effectively is connected with draw-bar (5), this draw-bar (5) is supported on the rod end (3) of import/exhaust door (1) with its free end, and be placed in its other end and form being configured on the gap compensating element (6) on the cylinder head of floating bearing (6.1), this other end is connected with the device (20) that is used for respect to stroke transfer unit (4) adjustment floating bearing (9).

2. valve actuating mechanism according to claim 1 is characterized in that, gap compensating element (6) is configured in the piston skirt in the cylinder head in the marginal pore (18).

3. valve actuating mechanism according to claim 1 and 2 is characterized in that, is formed with to be used for the device adjusted by the eccentric adjusting sleeve (20) as the accommodation apparatus of gap compensating element (6) usefulness that is connected with cylinder head.

4. according to a described valve actuating mechanism in the claim 1 to 3, it is characterized in that the eccentric adjusting sleeve (20) with a regulation eccentricity (e) constitutes available eccentric adjusting sleeve with another regulation eccentricity (e) and replaces.

5. according to a described valve actuating mechanism in the claim 1 to 3, it is characterized in that eccentric adjusting sleeve (20) can dispose with reversing.

6. according to a described valve actuating mechanism in the claim 1 to 5, it is characterized in that, be provided with and be used for eccentric adjusting sleeve (20) is fixed on device (24) on the cylinder head.

7. according to a described valve actuating mechanism in the claim 1 to 6, it is characterized in that, the adjustment axis (6.2) of gap compensating element (6) in the plane of motion of draw-bar (5) with respect to mobile axis (1.1) tilted configuration of import/exhaust door (1).

8. according to a described valve actuating mechanism in the claim 1 to 7, it is characterized in that, eccentric adjusting sleeve (20) has radially attachment hole (21), this radially attachment hole (21) be used for making pressure oil to penetrate in the gap compensating element (6) from the pressure oil duct (23) of cylinder head.

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