EP1605141B1 - Vane type camshaft phaser - Google Patents

Description

Field of the invention

The invention relates to a vane-type camshaft adjuster with a stator, a rotor connectable to a camshaft having a plurality of radially projecting vanes inserted in vane grooves, wherein a vane groove has groove side surfaces, a groove bottom and the groove side surfaces undercut, rounded transition regions between the groove side surfaces and the groove bottom ,

Background of the invention

Camshaft adjusters are used to change the timing for opening or closing the valves. The fixed angular relationship between the camshaft and the crankshaft driving it is thereby canceled and the timing can be optimally adjusted depending on the speed and other parameters. Camshaft adjusters allow a relative rotation of the camshaft to the crankshaft.

Known vane-type camshaft adjusters include a rotor having a plurality of radially projecting vanes which are urged radially outwardly against a stator housing by the force of a spring. On the stator a plurality of radially inwardly projecting stops are formed, which limit the adjustment movement of the rotor in both directions of rotation when the wings run against the stops. The wings abut with their end edges on the stator, so that between each one wing side and the adjacent side of a stop of the stator, a chamber is formed, in which a fluid, usually the engine oil, is conveyed via a valve associated with the camshaft adjuster. The stator serves on the one hand for separating and sealing the fluid chambers, on the other hand for fixing the adjustment angle between the camshaft and the crankshaft.

The torque introduced into the rotor is supported on the stator via the grooves in the grooves and hydraulically on the oil cushion in the stator chambers. The force acting thereon on the wings in turn causes reaction forces in the groove of the rotor. A force acts on the groove edge on the rotor outer diameter, the associated reaction force acts on the opposite groove side in the groove bottom. These forces cause a combined tensile and bending stress in the two transitions of the groove side surface to the groove bottom. In the corner region at the transition of the groove side surface to the bottom of the groove a dynamically occurring stress concentration is generated by the notch effect. For this reason, the transition region in conventional vane-type camshaft adjusters is rounded, so that it undercuts the groove side surface. However, significant stresses still occur in the corner area, which can be critical at the usual operating loads for the materials used.

The JP 11 159 309 discloses a vane phaser with vanes inserted in each groove of the rotor, the range of angular displacement between the rotor and the stator being defined by the contact between the vanes of the stator and the rotor.

The EP 1 229 216 A1 discloses a vane actuator with a stator and a rotor, wherein a locking pin is provided which communicates via a hydraulic fluid channel with one of the pressure chambers, wherein in the locked position of the locking pin of this hydraulic fluid channel is interrupted. The US 2004/0074458 A1 discloses a vane-type adjuster according to the preamble of independent claim 1.

Summary of the invention

The invention is therefore based on the object to provide a vane-camshaft adjuster, occur in the lower voltages.

To solve this problem is provided according to the invention in a vane-type camshaft adjuster of the type mentioned that the rounded transition areas are at least partially formed as the groove bottom undercut circular arc sections.

In the vane-type camshaft adjuster according to the invention, the groove bottom is not flat, but rather the corner regions are designed as arcuate sections that undercut the groove base. Only the central region of the groove bottom is flat, since there is a spring supported. The solution according to the invention has the advantage that only minor manufacturing changes are required. Due to the optimized cross-section of the vane groove, the stress can be reduced, in particular in the transition region, so that higher-grade materials can be dispensed with, which results in cost savings.

In the vane-type camshaft adjuster according to the invention, the distance of the lower end of the groove side surface from the groove bottom to the groove width may be in a ratio of 0.4 to 0.55, in particular approximately 0.48. With these parameters, the stress concentration in the transition region can already be considerably reduced. The groove width is sufficiently dimensioned so that the wings inserted into the wing groove can withstand the occurring forces.

In the vane-type camshaft adjuster according to the present invention, it is particularly preferable that the radius of the circular arc portions is 0.5 times to 0.6 times the distance of the lower end of the groove side surface from the groove bottom. In particular, the radius may be 0.56 times the distance.

It can also be provided that the horizontal distance of the center point of a circular arc portion from the symmetry line of the groove is 0.3 times to 0.4 times the groove width. The value of 0.35 is particularly preferred.

In the vane-type phaser of the present invention, the vertical distance of the center of the circular arc portion from the groove bottom may be 0.90 times to 0.99 times the radius of the circular arc portion. Particularly preferred is the value 0.95. The specified geometric values and parameters are not rigid limits, they can be varied as long as this results in the desired voltage reduction.

In the vane-type camshaft adjuster according to the invention, a further optimization of the occurring stresses can be achieved if a groove side surface has a relief notch. In this embodiment of the invention, the geometric optimization is not limited to the rounded transition region, since the groove side surface also has an optimized shape. Due to the relief notch, the force flow is smoothly deflected from the upper edge of the groove in the direction of the rotor center in a wide arc, so that no high concentration of stress occurs in the groove bottom. The occurring forces and stresses are distributed more evenly by the relief notch, so that the material stress is reduced.

It is particularly preferred that the relief notch is spaced from the groove base end of the groove side surface. The wing is thus at the upper, outer end of the groove, further, the wing is located between the relief notch and the rounded portion near the groove bottom at the groove side surfaces so as to be guided in the groove.

A particularly effective voltage reduction can be achieved if the relief notch of the vane-type camshaft adjuster according to the invention is at least partially formed as a circular arc section. When using a circular arc section is omitted on corners that could lead to an increase in voltage.

In a further embodiment of the invention, it may be provided that the nutgrundseitige end of the relief notch is approximately perpendicular and the opposite end of the relief notch tangent to the groove side surface. With a rotor constructed in this way, a considerable reduction of the stresses can once again be achieved.

It can also be provided that the radius of the circular arc section in the region of the groove bottom is selected such that it opens tangentially into the circular arc section of the relief notch. Accordingly, an envelope can be placed by the boundary of both arc sections, which has a certain radius.

Optimum stress ratios can be achieved if the radius of the circular arc section in the area of the relief notch is 0.75 times to 0.85 times the groove height. Particularly preferred is a value of 0.81.

In the vane-type camshaft adjuster according to the invention, the radius of the arcuate section in the area of the groove base may be approximately 0.20 times to 0.28 times the radius of the circular arc section in the region of the relief groove. Particularly preferred is a value of 0.24.

Brief description of the drawings

Fig. 1

shows a conventional vane-cam phaser with a stator and a rotor with inserted wings;

Fig. 2

shows an enlarged section of Fig. 1 in the area of a wing groove;

Fig. 3

shows the vane groove of a camshaft adjuster according to a first embodiment of the invention; and

Fig. 4

the vane groove of a camshaft adjuster according to a second embodiment of the invention.

Detailed description of the drawings

Fig. 1 1 shows a conventional vane-type phaser 1 comprising a stator 2 and a rotor 3 with a plurality of vanes 5 inserted in vane grooves 4.

The stator 2 is part of a chain or belt drive, whereby the rotation of the crankshaft is transmitted via a chain or a belt via the stator 2 and the rotor 3 to a camshaft. The stator 2 has projections 6, which serve as stops for the wings 5. In Fig. 1 is the wing 5 in an end position. In the rotor 3 are on the left and the right side of each wing groove 4 holes through which a fluid in a chamber adjacent to the wings 5 can flow in or out. By the incoming or outflowing fluid, a relative rotation between the rotor 3 and the stator 2 and thus between the crankshaft and the camshaft of an internal combustion engine is achieved.

On the wing 5 engages the arrow 7 shown as an arrow, which counteracts the acting on the shaft of the rotor 3 torque 8.

Fig. 2 shows an enlarged section of Fig. 1 in the area of the wing groove 4.

The force acting on the wing 5 causes a reaction force 9 at the outer end of the groove side surface 10. At the same time, a further reaction force 11 is produced on the opposite groove side surface 12. The forces 9, 11 cause a combined tensile and bending stress in the region of the transitions of the groove side surfaces 10, 12 towards the groove bottom 13. Although the transition between the groove base 13 and the groove side surfaces 10, 12 is formed as an undercut in the Nutseitenfläche, enter the Corner areas, especially in the Fig. 2 left corner shown very high stresses in the material.

Fig. 3 shows the vane groove of a camshaft adjuster according to the first embodiment of the invention.

The contour of the conventional vane groove according to Fig. 2 is in Fig. 3 dashed lines shown for comparison.

At the in Fig. 3 Wing groove 14 shown, the rounded transition regions between the groove side surfaces 15, 16 and the groove bottom 17 as a circular arc sections 18, 19 are formed, which undercut the groove bottom 17 at least partially. Calculations have shown that by the in Fig. 3 shown optimized geometry, a reduction of the maximum principal stress by 13% can be achieved.

In the illustrated embodiment, the distance of the lower end of the groove side surface 15, 16 from the groove bottom 17 and the width of the wing groove 14 in a ratio of about 0.48 to each other. The radius of the circular arc sections 18, 19 is 0.56 times the distance of the lower end of the groove side surfaces 15, 16 from the groove bottom 17. The horizontal distance of the center of the circular arc section 18, 19 from the symmetry line of the wing groove 14 is the 0.35- times the width of the wing groove 14. The vertical distance the center point of the circular arc sections 18, 19 to the groove bottom 17 is 0.95 times the radius of the circular arc sections 18, 19th

Fig. 4 shows the vane groove of a camshaft adjuster according to a second embodiment of the invention.

Unlike the one in Fig. 3 In the embodiment shown, the wing groove has relief notches 28, 29 in the region of the groove side surfaces 26, 27. The relief notches 28, 29 are spaced from the nutgrundseitigen end 30, 31 of the groove side surfaces 26, 27, so that a wing in this area on the Nutseitenflächen 26, 27 abuts and is guided.

The relief notches 28, 29 are at least partially formed as a circular arc portion having a radius 32. The nutgrundseitige end of the relief groove 28, 29, the Fig. 4 lower end, approximately perpendicular to the groove side surface 26, 27. The opposite end, the in Fig. 4 upper end of the relief notch 28, 29 extends tangentially to the groove side surface 26, 27. Since the radius 32 of the relief notches 28, 29 at least partially coincides with the radius of the circular arc sections 33, 34 in the region of the groove bottom 35, the power flow from the upper edge of the groove in deflected in a wide arc, leaving in the corner areas, especially near the in Fig. 4 left arc section shown 33 the formation of stress concentrations is avoided.

The radius 36 of the circular arc section 33, 34 in the region of the groove bottom 35 is selected such that the circular arc section 33, 34 opens tangentially into the circular arc section of the relief notch 28, 29.

The radius 32 of the circular arc section in the region of the relief notch 28, 29 in the illustrated embodiment is 0.81 times the groove height 37. The radius 36 of the circular arc section 33, 34 in the region of the groove bottom 35 is 0.24 times the radius 32 of the circular arc section in the region of the relief notch 28, 29.

Calculations have shown that by the optimized geometry according to the second embodiment, a voltage reduction of 30% is achieved. <B> numerals </ b> 1 Vane-type camshaft adjuster 26 groove side 27 groove side 2 stator 28 relief notches 3 rotor 29 relief notches 4 vane 30 End of groove side surface 5 wing 31 End of groove side surface 6 head Start 32 radius 7 force 33 Arc section 8th torque 34 Arc section 9 reaction force 35 groove base 10 groove side 36 radius 11 reaction force 37 groove height 12 groove side 13 groove base 14 vane 15 groove side 16 groove side 17 groove base 18 Arc section 19 Arc section 20 groove width 21 horizontal distance 22 vertical distance 23 vertical distance 24 radius 25 vane

Claims (12)

1. Vane-type camshaft adjuster (1) having a stator (2) and a rotor (3), which latter can be connected to a camshaft and comprises a plurality of radially protruding blades (5) inserted in blade grooves (4, 14, 25), a blade groove (4, 14, 25) having groove side faces (10, 12, 15, 16, 26, 27), a groove bottom (13, 17, 37) and rounded transition regions between the groove side faces (10, 12, 15, 16, 26, 27) and the groove bottom (13, 17, 37), which transition regions undercut the groove side faces (10, 12, 15, 16, 26, 27), wherein the middle region of the groove bottom (13, 17, 37) is flatly configured and a spring rests there, characterized in that the rounded transition regions are configured, at least in part, as circular arc segments (18, 19, 33, 34) which undercut the groove bottom (13, 17, 35).
2. Vane-type camshaft adjuster (1) according to Claim 1, characterized in that the ratio of the distance (23) of the lower end of the groove side face (15, 16) from the groove bottom (17) relative to the groove width (20) is 0.4 to 0.55, more particularly approximately 0.48.
3. Vane-type camshaft adjuster (1) according to Claim 1 or 2, characterized in that the radius (24) of the circular arc segments (18, 19) amounts to 0.5 times to 0.6 times, more particularly 0.56 times, the distance (23) of the lower end of the groove side face (15, 16) from the groove bottom (17).
4. Vane-type camshaft adjuster (1) according to one of the preceding claims, characterized in that the horizontal distance (21) of the midpoint of the circular arc segment (18, 19) from the line of symmetry of the groove (14) amounts to 0.3 times to 0.4 times, more particularly 0.35 times, the groove width (20).
5. Vane-type camshaft adjuster (1) according to one of the preceding claims, characterized in that the vertical distance (22) of the midpoint of the circular arc segment (18, 19) to the groove bottom (17) amounts to 0.90 times to 0.99 times, more particularly 0.95 times, the radius (24) of the circular arc segment (18, 19).
6. Vane-type camshaft adjuster (1) according to one of the preceding claims, characterized in that a groove side face (26, 27) has a relief notch (28, 29).
7. Vane-type camshaft adjuster (1) according to Claim 6, characterized in that the relief notch (28, 29) is distanced from the groove-bottom-side end (30, 31) of the groove side face (26, 27).
8. Vane-type camshaft adjuster (1) according to Claim 6 or 7, characterized in that the relief notch (28, 29) is configured, at least in part, as a circular arc segment.
9. Vane-type camshaft adjuster (1) according to Claim 8, characterized in that the groove-bottom-side end of the relief notch (28, 29) runs approximately perpendicularly and the opposite end of the relief notch (28, 29) runs tangentially to the groove side face (26, 27).
10. Vane-type camshaft adjuster (1) according to Claim 8 or 9, characterized in that the radius (36) of the circular arc segment (33, 34) in the region of the groove bottom (35) is chosen such that it leads tangentially into the circular arc segment of the relief notch (28, 29).
11. Vane-type camshaft adjuster (1) according to one of Claims 8 to 10, characterized in that the radius (32) of the circular arc segment in the region of the relief notch (28, 29) amounts to 0.75 times to 0.85 times, more particularly 0.81 times, the groove height (37).
12. Vane-type camshaft adjuster (1) according to one of Claims 8 to 11, characterized in that the radius (36) of the circular arc segment (33, 34) in the region of the groove bottom (35) amounts to about 0.20 times to 0.28 times, more particularly 0.24 times, the radius (32) of the circular arc segment in the region of the relief notch (28, 29).

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