192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
1998-12-15
2001-11-13
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C192S046000
Reexamination Certificate
active
06315098
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the field of clutch mechanisms, and, in particular, to a rolling element clutch. More particularly, the present invention relates to a multi-mode rolling element clutch.
2. Description of the Related Art
A freewheel clutch is a device that will drive a rotating load in one direction, but will allow it to freewheel or spin at any speed in the other direction. There is a need to make a more compact and rugged freewheel clutch. Most current designs need separate devices to support a non-drive load on the shaft and to have the shaft transmit a drive load. Current techniques are called ratchet and pawl, wrap spring, sprag, roller clutch, ball clutch, tilting plate, and so forth. Each of these related art devices needs the addition of some bearing device to support the non-drive load when it is in the freewheel mode.
Typical of the related art is U.S. Pat. No. 4,635,771, which discloses a one-way clutch bearing having an outer race with an annular inner surface, an inner race with an annular outer surface corresponding to and concentric with the inner surface, and rolling members disposed in an annular space formed between the inner surface and the outer surface, whereby relative rotation of the inner and outer races in one direction is prevented by displacement of the rolling members in the space and a torque is transmitted. A holding means for holding the rolling members is provided at a displacement position whereat the rolling members transmit a predetermined transmission torque, and a means is provided for decreasing a wedge angle at a position before the rolling members arrive at the displacement position.
U.S. Pat. No. 5,573,094, which is assigned in common with the present invention and incorporated herein by reference, discloses a combination bearing/freewheel clutch which is provided with an inner race member defining an inner race surface, an outer race member defining an outer race surface concentric with the inner race member, and a raceway between the inner and outer races. The inner and outer race members each have a series of short radially oriented sawtooth inclines in their respective inner and outer race surfaces at right angles to the raceway. A plurality of modified ball bearings, for instance ball bearings have flattened poles, are disposed in the raceway between the inner and outer race members, such that the modified ball bearings serve to prevent relative rotation of the inner and outer race members in one direction, and to transmit a torque between the inner and outer races.
U.S. patent application Ser. No. 09/206,618 (attorney docket number: 98-903), titled “A Rolling-Element Clutch Assembly,” and filed Dec. 7, 1998, is assigned in common with the present invention and incorporated herein by reference. Application Ser. No. 09/206,618 discloses a plurality of improvements to the invention of U.S. Pat. No. 5,573,094.
The invention of U.S. Pat. No. 5,573,094 represents a significant development in the art of combination bearing/freewheel clutches. However, there is a need for a multi-mode rolling element clutch assembly that, in a first configuration, supports a non-drive load between two components while allowing the components to freely move relative to one another in a first direction and transmits a drive load between the two components when the two components attempt to move relative to one another in a second direction, and that can easily and reliably be converted into a second, reversed configuration that transmits the drive load in the first direction and allows the non-drive load to move freely in the second direction.
SUMMARY OF THE INVENTION
The multi-mode rolling element clutch assembly of the present invention reduces the mechanical complexity, volume and weight normally required if more traditional devices are used. A single multi-mode rolling element clutch assembly may replace the separate bearings, electromechanical clutches, and/or combinations of brakes and freewheels in any given application. Accordingly, the present invention may find application in fail safe designs for conveyors, elevators, escalators, cable cars, machine tools, monorail trains, etc. The present invention may also provide an anti-backlash capability that could, for instance, replace holding brakes and other devices, add safety and stability to rack-and-pinion steering mechanisms and material feed mechanisms, and augment and stiffen linear actuators.
The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages and purposes of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the multi-mode rolling element clutch assembly, in a first aspect, includes a first race member defining a first race surface having a first ratchet surface portion, a second race member defining a second race surface, the first race surface and the second race surface defining a raceway therebetween, and a plurality of rolling elements disposed in the raceway. The first ratchet surface portion has a first multi-mode ratchet mechanism for providing a first and a second ratchet configuration. When the first multi-mode ratchet mechanism is in the first ratchet configuration, the rolling elements may provide rolling support between the first race member and the second race member when the first race member moves in a first direction relative to the second race member, and at least one of the plurality of rolling elements may engage the first ratchet surface portion when the first race member moves in a second direction relative to the second race member, thereby impeding relative motion between the first race member and the second race member and providing load transmission capability. When the first multi-mode ratchet mechanism is in the second ratchet configuration, the rolling elements may provide rolling support between the first race member and the second race member when the first race member moves in the second direction relative to the second race member, and at least one of the plurality of rolling elements may engage the first ratchet surface portion when the first race member moves in the first direction relative to the second race member, thereby impeding relative motion between the first race member and the second race member and providing load transmission capability. The first multi-mode ratchet mechanism may include at least one ratchet segment movable from a first position to a second position, a ratchet wall defining at least one concavity for accommodating the at least one ratchet segment, and a reversing member coupled to the at least one ratchet segment and for moving the at least one ratchet segment from the first position to the second position.
In a second aspect, the invention encompasses a method of operating the multi-mode rolling element clutch assembly having a first race member defining a first race surface and a first ratchet portion, a second race member defining a second race surface, the first and second race surfaces defining a raceway therebetween, a plurality of rolling elements disposed in the raceway, and the first ratchet portion having a first multi-mode ratchet mechanism for providing a first and a second ratchet configuration. The method includes the steps of operating the first multi-mode ratchet mechanism to establish the first ratchet configuration; providing rolling support, via the rolling elements, between the first and second race members when the first race member moves in a first direction relative to the second race member; operating the first multi-mode ratchet mechanism to establish the second ratchet configuration; and providing rolling support, via the rolling elements, between the first and second race
Bonck Rodney H.
General Dynamics Goverment Systems Corporation
Jenner & Block LLC
Rodriguez Saul
LandOfFree
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