US20090211549A1

US20090211549A1 - Cam phase adjuster with a plurality of springs

Info

Publication number: US20090211549A1
Application number: US12/389,854
Authority: US
Inventors: Jesse Myers; Gregory Muller; Roger MYER
Original assignee: Schaeffler KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2008-02-21
Filing date: 2009-02-20
Publication date: 2009-08-27

Abstract

The camshaft adjuster is a plurality of return springs which are in parallel to one another in a spring.

Description

FIELD OF THE INVENTION

This Invention relates to cam phase adjusters used for adjusting the angular relative position of the camshaft in relation to the crankshaft and, more particularly, to vane-type camshaft phasers having a stator and a rotor.

BACKGROUND OF THE INVENTION

Vane-type phasers are conventional devices used especially in motor vehicles in order to adjust the angular position of a camshaft in relation to the crankshaft of the internal combustion engine. The device uses a stator and a rotor to adjust the angular position of the camshaft in relation to the crankshaft. The stator rotates on the camshaft and is rotated by a belt or chain from the crankshaft. The rotor is fixed to the camshaft. The stator has a plurality of pressure chambers, each of which are divided by the vanes of the rotor. By applying a pressure medium, typically oil, into the pressure chamber on either side of the rotor vane, the angular relationship between the stator and the rotor is changed and, hence, the relative angular position between the crankshaft and the camshaft is adjusted.
Typically, a return spring, such as a flat spiral spring, is used to return the rotor to an initial rest position when the engine is turned off. One of the problems is that when the overall camshaft drag torque is high, a single return spring is not adequate or is too slow. In certain cases, hydraulic pressure is used to assist the return spring, however, hydraulic pressure can detract from the efficiency of the engine.

OBJECT OF THE INVENTION

It is the object of the present Invention to provide a spring design which provides an adequate level of return spring compensation for a phaser so as to have consistently balanced shifting speeds in the advanced and retard timing directions. It is also the object of the present Invention to provide a reliable unlocking of the locking mechanism of the phaser in locked position. It is furthermore, the object of the present Invention to accomplish high return spring torques in a set area of space.
These and other objects of the present Invention will be more readily understood by reference to the following description of the Invention.

SUMMARY OF THE INVENTION

The present Invention obtains these objects by an improved spring design in which a plurality of return springs is used. Furthermore, robustness and durability of the phaser is also improved by employing a plurality of return springs in the phaser. The overall working stress on each of the individual return springs can be lowered because of the plurality of return springs and therefore increase the factor of safety for the return springs as a whole.
More specifically, a plurality of return springs is assembled in parallel in the camshaft phaser. The plurality of parallel return springs provide a high return spring compensation when the overall camshaft drag torque is at levels which are too high to be compensated for by a single spring. The total summation of torque from the plurality of return springs is suitably higher than the overall camshaft drag torque.
Broadly, the present Invention can be defined as a camshaft phaser adjuster comprising:
a stator and a rotor adjustable to the stator in a circumferential direction by a pressure medium;
at least one spring chamber proximately located adjacent to the stator and the rotor; and
a plurality of return springs proximately arranged in the spring chamber, each of the springs having a rotor connecting end for connecting to the rotor and a stator connecting end for connecting to the stator, the return springs configured to rotate the rotor relative to the stator into an initial position absent pressure from the pressure medium.
In the preferred embodiment, the spring chamber is axially adjacent to the stator and rotor and the plurality of return springs are arranged axially adjacent to one another in the spring camber. Multiple spring cambers and other spring arrangements such as co-axial return springs will occur to those skilled in the art and are within the scope of the present invention.
Preferably, the number of return springs is two or more; and, more preferably, the number of return springs is two to four.
Suitably, the return springs are flat spiral springs. Each of the springs preferably has equal strength, however, equal strength springs are not required. There could be a scenario where different strengths are used. IE. 3 Nm+5 Nm=8 Nm or 4 Nm×2=8 Nm.
One of the unique aspects of the present Invention is the fact that each of the return springs is identical in both strength and size. This leads to a balance of the torque and a cost savings and simplicity because of only one type of spring component part is used for several different outputs for different assemblies.
In order to allow for the use of a plurality of return springs, the support(s) for the springs are increased in length and the spring chamber, which is defined by the spring outer housing, is increased or deepened to accommodate the side-by-side axial arrangement of the return springs.
When the phaser of the present Invention is assembled, all return springs are wound simultaneously in the same manner as a single return spring is wound. The multiple return springs supply adequate torque to counteract the high camshaft drag torque of the engine. This yields balanced shifting speeds and excellent phaser unlocking behavior. Balanced shifting velocities and excellent unlocking behavior is just one of the unique advantages of the present Invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present Invention may be more readily understood by reference to one or more of the following drawings which are herein presented for purposes of illustration only.

FIG. 1 illustrates a cross section of the camshaft phase adjuster of the present Invention;

FIG. 2 illustrates an exploded view of the adjuster;

FIG. 3 illustrates a cutaway view of the adjuster;

FIG. 4 illustrates an axial view of the adjuster;

FIG. 5 illustrates a cross section of an alternate embodiment of the camshaft phase adjuster of the present Invention; and

FIG. 6 illustrates an exploded view of a further alternate embodiment of the camshaft phase adjuster of the present Invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate a phase adjuster 10 with stator 12 fixedly mounted inside sprocket 14, with locking cover 16 and sealing cover 17 sealing stator pressure chambers 20. Lugs 18 of stator 12 divides stator 12 into pressure chambers 20 in a conventional manner. Stator 12 is fixed to drive wheel 14 and drive wheel 14 is driven by the crankshaft of the engine.
Rotor 22 is fixed to camshaft 23 as shown in FIGS. 3 and 4. Rotor 22 has vanes 24 which reside in pressure chamber 20. Pressure chamber 20 is divided by vanes 24 into one half 26 and another half 28. Pressure medium is pumped into one of the half chambers 26 or 28 in order to rotate the rotor with respect to the stator. Such operation is conventional.
Spring chamber 30 is defined by trigger wheel 31 which acts as an outer housing and locking cover 16. Drive screws 11 fixes housing 31 to rotor 22.
Arranged adjacent to one another in spring chamber 30 are spiral springs 34 and 36. Each spiral springs 34 and 36 has a rotor connecting end 38 and 40, respectively, and a stator connecting end 42 and 44, respectively. Each of the spring ends is, in turn, connected to a respective rotor stop 46, 48 and a stator stop 50, 52.
An alternate embodiment is illustrated in FIG. 5 wherein the phase adjuster 54 is comprised of spring chamber 56. Arranged concentric to one another in spring chamber 56 are inner spring 58 and outer spring 60. Preferably, inner spring 58 and outer spring 60 are flat spiral springs; although the invention does not preclude inner spring 58 and outer spring 60 made of different springs such as coil springs.
A further alternate embodiment is illustrated in FIG. 6 wherein the phase adjuster 62 is comprised of left spring chamber 64 and right spring chamber 66. Arranged in spring chamber 64 is left spring 68 and arranged in spring chamber 66 is right spring 70. Preferably, left spring 68 and right spring 70 are flat spiral springs; although the invention does not preclude left spring 68 and right spring 70 made of different springs such as coil springs.

REFERENCE CHARACTERS

10. Phase adjuster
11. Drive screws
12. Stator
14. Sprocket
16. Locking cover
17. Sealing cover
18. Lugs of stator
20. Pressure chambers
22. Rotor
23. Camshaft
24. Vanes of rotor
26. One half pressure chamber 20
28. Other half pressure chamber 20
30. Spring chamber
31. Trigger wheel
32. Spring support bolt
34. Spiral spring
36. Spiral spring
38. Rotor connecting end
40. Rotor connecting end
42. Stator connecting end
44. Stator connecting end
46. Rotor stop
48. Rotor stop
50. Stator stop
52. Stator stop
54. Phase adjuster
56. Spring chamber
58. Inner spring
60. Outer spring
62. Phase adjuster
64. Left spring chamber
66. Right spring chamber
68. Left spring
70. Right spring

Claims

1. A camshaft phase adjuster comprising:

a stator and a rotor adjustable to the stator in a circumferential direction by a pressure medium;

at least one spring chamber proximately located adjacent to the stator and the rotor; and

a plurality of return springs proximately arranged in the spring chamber, each of the springs having a rotor connecting end for connecting to the rotor and a stator connecting end for connecting to the stator, the return springs configured to rotate the rotor relative to the stator into an initial position absent pressure from the pressure medium.

2. The adjuster of claim 1, wherein

the spring chamber is axially adjacent to the stator and the rotor.

3. The adjuster of claim 1, wherein

the plurality of return springs are arranged axially adjacent to one another in the spring chamber.

4. The adjuster of claim 1, wherein

the plurality of return springs is 2 or more.

5. The adjuster of claim 1, wherein

the return springs are flat, spiral springs.

6. The adjuster of claim 1, wherein

each of the return springs has an equal strength.

7. The adjuster of claim 2, wherein

the plurality of return springs is 2 to 4.

8. The adjuster of claim 1, wherein the return springs are not of equal strength.