192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
1998-07-06
2001-01-09
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C029S446000
Reexamination Certificate
active
06170626
ABSTRACT:
FIELD OF THE INVENTION
A clamping roller overrunning clutch, each of whose clamping rollers is urged against clamping tracks by at least one spring element. The clamping rollers of such overrunning clutches are normally urged by spring elements into wedge-shaped gaps formed by the clamping tracks, one of which clamping tracks has a ramp-shaped contour and this spring-loading creates the constant locking readiness of the clamping roller overrunning clutch.
BACKGROUND OF THE INVENTION
In a clamping roller overrunning clutch known, for example, from GB-B 1,125,636, the spring means is a leaf spring bent in the form of an arc whose ends spring load the rollers. In the axial direction, the leaf spring is supported centrally on a crossbar and this means that this leaf spring is subjected to the maximum bending load in its central support contact. It has been observed in such spring arrangements that a strong setting of the spring elements takes place during operation which means that the spring force or the residual spring travel available until the block state of the spring is reached is no longer adequate for assuring a satisfactory spring loading of the clamping rollers. In such cases, a malfunctioning of the overrunning clutch can occur which is undesirable under all circumstances.
Residual spring travel designates the travel of the spring which remains after the setting of the spring from an unloaded starting position until the reaching of the block state. Due to the high dynamic bending load (the lever arm of the force between the point of force application and the point of support in the support contact is approximately half the leaf spring length), breaking of such spring elements has also been observed.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a clamping roller overrunning clutch in which a reliable spring loading of the clamping rollers into the clamping gaps is assured.
This and other objects and advantages of the invention will become obvious from the following detailed description.
SUMMARY OF THE INVENTION
The clamping roller overrunning clutch of the invention each of whose clamping rollers (
4
) is urged against clamping tracks (
5
) by at least one arc-shaped spring element, whose arc ends (
11
) are suspended against the clamping rollers (
4
), is characterized in that a support surface (
10
) for the arc-shaped spring element extending between the arc ends (
11
) is made so that a support contact (A, A′, A″) between the support surface (
10
) and the arc-shaped spring element (
6
) migrates towards the arc ends (
11
) of the arc-shaped spring element (
6
) with increasing load. Firstly, the dynamic bending loading of the spring elements of the clamping roller overrunning clutch of the invention is lower than in the case of the aforementioned known spring elements which is due to the fact that the lever arm between the point of application of the force and the point of support of the spring element in the support contact on the support surface shortens as the load increases because, as a result of loading, the spring element comes to lie against the support surface. This necessarily results in a lowering of the bending moment and thus also of the bending load.
Advantageously, the arc-shaped leaf spring and the support surface are designed so that the elastic limit of the arc-shaped leaf spring is exceeded during the first load cycles to which the overrunning clutch is subjected so that a larger material cross-section sets than in known arrangements. Thus, in the ideal case, the entire cross-section of the spring is loaded up to the yield point in the region of maximum deflection and a setting of the spring during operation of the overrunning clutch is only minimal. In this way, it is assured that the residual spring travel available is larger than in conventional devices.
With a view to the spring setting process, the invention proposes a flat support surface which extends tangentially of the axial center of the unloaded arc-shaped spring element. It is, of course, also possible to use curved support surfaces. The only important thing is that the arc-shaped spring element comes to bear against the support surface with increasing load in the manner described above. Arc-shaped spring elements with a constant curvature are particularly easy to manufacture. It is understood that the advantages of the invention can also be assured with arc-shaped spring elements having a non-uniform curvature.
Clamping roller overrunning clutches having a cage for receiving the clamping rollers can be used particularly favorably for fixing the arc-shaped elements of the invention. Normally, the clamping rollers are arranged in pockets of the cage which are circumferentially defined by crossbars of the cage. The arc-shaped spring elements of the invention are fixed on the crossbars, for example by clipping them onto the crossbars, or by forming them integrally on the crossbars. A surface of the crossbar defining the pocket can be simultaneously used as a support surface for the arc-shaped spring element.
The clamping roller overrunning clutch of the invention can be made by the following steps. In a first step, the curved spring elements are inserted into the overrunning clutch. The clamping rollers and the spring elements are then pressed against one another, preferably during the first load cycles in operation leading to the desired setting of the springs. However, it is also possible to perform this pressing step using suitable equipment before taking the clamping roller overrunning clutch into operation. The loading of the spring elements in this pressing step is performed above the yield point but below the breaking point of the spring material. This loading results in a setting of the spring elements.
While in prior art clamping roller overrunning clutches a setting of the spring elements is rather unintended and occurs during operation with the initially described disadvantages, the method of the invention guarantees a perfect operation of the clamping roller overrunning clutch because the setting of the spring elements is effected in a controlled manner during the first load cycles and, after this intended setting, a minimum spring loading of the clamping rollers by the spring elements is assured. Prior to insertion into the clamping roller overrunning clutch, the spring elements are configured with a curvature and an arc length which are chosen so that, on insertion into the clamping roller overrunning clutch, the spring loading of the clamping rollers by the spring elements is at first higher. After completion of the intended setting process, the spring load reduces but is still adapted to the operating conditions.
The method of the invention is not limited to the examples of embodiment described herein. The determining factor is only that the shape and size of the spring elements should permit the use of the described method which assures that an unintended setting of the springs during the operating life is replaced by an intended setting which is substantially completed at the beginning of initial operation of the overrunning clutch.
REFERENCES:
patent: 1798526 (1931-03-01), Fitzgerald
patent: 2835364 (1958-05-01), Picard et al.
patent: 3192551 (1965-07-01), Appel
patent: 3404760 (1968-10-01), Benson et al.
patent: 3500977 (1970-03-01), Gehrke
patent: 4549638 (1985-10-01), Johnston
patent: 4711330 (1987-12-01), Lederman
patent: 4834227 (1989-05-01), Lederman
patent: 5007514 (1991-04-01), Hattori et al.
patent: 1286843 (1969-01-01), None
patent: 9090147 (1991-10-01), None
patent: 4216055 (1993-11-01), None
Hideo Mibe, “One Way Clutch and its Manufacture” Patent Abstracts of Japan, JP 4-191536, M-1330, Oct. 26, 1992, vol. 16, No. 519.
Bierman, Muserlian and Lucas
Ina Walzlager Schaeffler OHG
Lorence Richard M.
LandOfFree
Clamping roller overrunning clutch and method of making same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Clamping roller overrunning clutch and method of making same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clamping roller overrunning clutch and method of making same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2451622