192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2002-11-18
2004-03-16
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S064000, C192S071000, C280S237000
Reexamination Certificate
active
06705443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a freewheel clutch which is shiftable in two rotational directions. The invention also relates to a method of transmitting power using a freewheel clutch which is shiftable in two rotational directions.
2. Background of the Invention
Freewheel clutches or freewheels are known in bicycle engineering. Austrian application AT-194253, for instance, discloses a freewheel and gear hub having a back-pedal brake for bicycles wherein ratchets operate without any noise. These ratchets are controlled by a friction sleeve which frictionally slides in the sleeve or in an annular member which is fixedly connected to the hub sleeve. The friction sleeve includes recesses for the ratchets, noses for limiting the rotation, and frictional slide springs which rest on the annular member.
Furthermore, U.S. Pat. No. 2,181,665 shows a simple construction of a freewheel acting in one direction. In this design, a spring-biased ratchet engages in recesses which are provided for the ratchet upon rotation of the hub in one direction. However, it does not engage in the recesses upon rotation in the other rotational direction.
Furthermore, German application DE-3326420 shows a freewheel clutch which utilizes a driving clutch, half of which includes two axially offset eccentrics. However, the freewheel clutch is intended only for transmitting a rotational movement from a drive element to a driven element in one direction of rotation. Moreover, an independent free rotational movement of the driven element is ensured in the same direction of rotation when the speed thereof exceeds that of the drive element.
Despite the great number of solutions offered in the field of bicycles or similar devices, there continues to exist a need for a freewheel clutch which can be utilized, in particular, in pedal vehicles for children such as tricycles or Kettcars® which allow pedaling in both the forward direction and the rearward direction from an initial inoperative position. Such a design should easily permit both a forward movement and a rearward movement, respectively, of the vehicle. Furthermore, there is also a need for a freewheeling design which acts in both directions and prevents the pedals from rotating, for instance, during travel on a sloping terrain or while the vehicle is being pushed. Moreover, since a pedal drive acts in both directions, the freewheel must also be operative in both directions for reasons of safety. Accordingly, such a design may make these devices safer by preventing a user from injuring their legs or feet on the pedals.
SUMMARY OF THE INVENTION
The present invention provides for a freewheel clutch of simple construction and relatively low manufacturing costs which is shiftable in both rotational directions and includes a freewheel condition which acts in both rotational directions.
According to the invention, there is provided a freewheel clutch which is shiftable in both rotational directions, e.g., forwards or backwards, clockwise or counterclockwise, etc., and which includes a double-acting freewheel. The clutch includes a driver or catch which is fixedly and/or securely connected to a drive shaft and further includes an engagement mechanism which is arranged between the drive shaft and a driven shaft.
Additionally, the freewheel clutch utilizes a holding element which engages the engagement mechanism and which is frictionally engaged with or frictionally coupled to a fixed member which may be a vehicle frame. A spring element is utilized in the clutch such that in the inoperative state of the drive shaft, the engagement mechanism is maintained out of engagement with the driven shaft. However, in the driven state of the drive shaft, the engagement mechanism is placed into engagement with the driven shaft via the catch.
Prior to engagement of the engagement mechanism with the driven shaft, the engagement mechanism is engaged by the holding element in a non-rotating or stationary state, while the drive shaft and the catch are rotating due to pedaling. A frictional force, which is maintained between the holding element and the fixed member, is designed to be greater than a resilient force which is exerted by the spring element. This design permits the engagement of the engagement mechanism with the driven shaft when the drive shaft is rotated a predetermined amount. Furthermore, the clutch utilizes an engagement force created between the engagement mechanism and the driven shaft, which is greater than the frictional force between the holding element and the fixed member. Accordingly, as a result of this design, a power transmission from the drive shaft to the driven shaft via the catch and the engagement mechanism is thereby made possible.
Thus, according to the invention, it is possible to drive the drive shaft forwardly or rearwardly (i.e., clockwise or counterclockwise) by pedaling a pedal vehicle. Moreover, this design easily achieves a forwardly directed movement or a rearwardly directed movement of the vehicle, depending on the respective drive direction of the drive shaft and/or pedals. Thus, the freewheel clutch according to the invention can be shifted into both rotational directions based upon movement of the pedals in the corresponding directions.
Furthermore, the invention provides a double-acting freewheel which makes it possible to move the pedal vehicle forwardly or rearwardly without pedaling. Accordingly, this design allows the pedals to remain stationary (e.g., not caused to be rotated) when the vehicle is pushed in either direction. Thus, when the vehicle is pushed in a forward direction, this movement will not cause forward corresponding movement of the pedals in the forward direction and vise versa. It is thus in particular possible to push pedal vehicles with children thereon forwardly or rearwardly without producing any rotation of the pedals. As a result, the risk of injury to the child's feet or legs is thereby reduced.
Preferably, the engagement mechanism which is located between the drive shaft and the driven shaft is designed such that it permits a positive lock or positive engagement between a driving part and a driven part. This positive engagement design ensures a reliable connection between the driving and the driven part. However, the invention also contemplates the use of frictional engagement by the engagement mechanism between the driving part and the driven part. Such a design allows for an even simpler construction of the freewheel clutch. Of course, in each of these embodiments, the frictional force between the engagement mechanism and the driven shaft must be greater than the frictional force between the holding element and the fixed member.
Preferably, the driven shaft is designed as an internally splined hollow shaft. This allows for a compact freewheel clutch which saves space, in particular, in the axial direction.
In order to provide for a simple construction of the freewheel clutch, the spring element is preferably designed as a spring washer or ring. The ring or washer may have an entirely annular shape or may be designed as a split ring or split washer so as to permit easy mounting and/or assembly/disassembly.
Advantageously, the engagement mechanism may be designed as a locking spline having external teeth or toothing. This design permits a reliable positive teeth to teeth engagement so as to connect or couple the drive shaft to the driven shaft.
In order to obtain a redundant engagement between the drive shaft and the driven shaft, the engagement mechanism may include two locks or engagement elements in which each engagement element utilizes an external spline, teeth or toothing.
Additionally, it is preferred that the catch be designed as a semi-annular element having two lateral wing sections. Utilizing this design, the semi-annular element part of the catch can easily be connected to the drive shaft, e.g. by conventional attachment techniques such as welding, bonding, fasteners, etc., or any combination thereof.
Moreover, in order to help reduce th
Kettler Heinz
Kettler Joachim
Rocholl Reinhard
Greenblum & Bernstein P.L.C.
Heinz Kettler GmbH & Co.
Lorence Richard M.
LandOfFree
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