Brakes – Operators – Electric
Reexamination Certificate
1999-08-24
2001-11-13
Oberleitner, Robert J. (Department: 3613)
Brakes
Operators
Electric
C188S171000, C192S090000
Reexamination Certificate
active
06315088
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to brakes and, in particular, to a spring-set, electromagnetically released brake requiring a relatively small amount of current for use in releasing the brake. This invention also relates to an improved coil bobbin for use in the inventive brake or other electromagnetic assembly and, in particular, to a coil bobbin that may be secured against movement within an electromagnetic assembly without bonding.
2. Disclosure of Related Art
A conventional spring-set, electromagnetically released brake includes an armature on which a brake shoe or other engagement element is disposed. A spring biases the armature and the engagement element towards a second engagement element, such as a friction surface. The brake further includes a coil disposed about a magnet pole or other ferromagnetic structure and means for energizing the coil. By energizing the coil, a magnetic circuit is established between the pole and armature in order to draw the armature towards the pole and the brake shoe away from the friction surface, thereby releasing the brake.
Conventional spring-set, electromagnetically released brakes often require relatively large amounts of current in order to overcome the biasing force of the spring and release the brake. As a result, these conventional brakes are relatively inefficient. Further, conventional spring-set, electromagnetically released brakes suffer from an undesirable amount of backlash as the brake is set.
Conventional coil bobbins used for retaining the coil in spring-set, electromagnetically released brakes and other electromagnetic assemblies also have disadvantages. These bobbins are typically secured within the assembly by bonding to prevent movement of the bobbin and the coil. Bonding, however, is a relatively expensive and inefficient process.
There is thus a need for a spring-set, electromagnetically released brake and a coil bobbin that will minimize or eliminate one or more of the above-mentioned deficiencies.
SUMMARY OF THE INVENTION
The present invention provides a spring-set, electromagnetically released brake as well as a coil bobbin for use in such a brake or other electromagnetic assembly.
An object of the present invention is to provide a spring-set, electromagnetically released brake that requires less current to release the brake as compared to conventional brakes.
Another object of the present invention is to provide a coil bobbin for use in a brake or other electromagnetic assembly that will restrict movement of the bobbin—and the coil retained by the bobbin—without bonding to a magnet pole or other structure within the assembly.
In accordance with the present invention, one embodiment of a spring-set, electromagnetically released brake includes a magnet shell disposed about a first axis. The magnet shell may be configured to receive a motor shaft extending along the first axis and includes a radially outwardly extending pole. The brake also includes an armature disposed radially outwardly of the pole and pivotable at a first axial end. The armature may be mounted to the magnet shell at its first axial end by a pivot pin extending in a direction perpendicular to the first axis. The brake further includes a first engagement element, such as a brake shoe, coupled to the armature proximate a second axial end of the armature. The brake further includes a spring disposed about the magnet shell pole. The spring biases the armature radially outwardly to urge the first engagement element towards a second engagement element, such as the inner surface of a brake drum coupled to the motor shaft. Finally, the brake includes a coil disposed about the pole and means for selectively energizing the coil to urge the armature radially inwardly and the first engagement element away from the second engagement element.
The pivoting motion of the armature and the relative positions of the armature and magnet shell pole allow a brake in accordance with the present invention to operate more efficiently as compared to conventional spring-set, electromagnetically released brakes. In particular, because the armature pivots at its first axial end, the second axial end of the armature containing the engagement element will travel a greater radial distance as the armature moves between a set position and a release position than those portions of the armature intermediate the first and second axial ends. The magnet shell pole is preferably located such that the axial center of the pole is intermediate the first and second axial ends of the armature. As a result, the average radial distance between the magnet shell pole and the armature when the armature is in the set position is less than the radial distance traveled by the second axial end of the armature as the armature moves between the set and release positions. This positioning allows a relatively small level of current to be used to move the armature and release the brake because the magnet shell pole and armature are relatively close even when the armature is in the set position.
One advantage of a brake in accordance with the present invention is a reduction in the amount of backlash when the brake is set as compared to conventional brakes. This reduction may be accomplished in several ways. First, the first axial end of the armature may be secured on a pivot pin held between two mounting posts on the magnet shell. The pivot pin is perpendicular to the first axis and, therefore, the axis of rotation of the brake drum and motor shaft. This arrangement reduces backlash in either rotational direction. Second, the inventive brake may include: (i) a coupling shaft having a female end with an axially extending slit configured to receive a key on the motor shaft and (ii) a collar disposed radially outwardly of the female end of the shaft and configured to clamp onto the key of the motor shaft. Finally, where the engagement elements form teeth disposed on the armature and brake drum, backlash may be reduced by angular placement of multiple armatures and/or their teeth so that the teeth on one armature are configured to fully engage the teeth on the brake drum while the teeth on another armature are configured to partially engage the teeth on the brake drum.
Other advantages of the present invention may be obtained by using multiple magnet shell poles, armatures, springs and coils. The use of multiple springs allows a braking torque to be applied in the event of a failure in any one spring. The use of multiple poles and coils enables the brake to be operated using various input voltages. For example, if the coils are connected in parallel a first voltage can be used. If the coils are connected in series, a second voltage (twice that of the first voltage) may be used.
A brake in accordance with the present invention may further include a bobbin to retain the coil about the magnet shell pole. A coil bobbin in accordance with the present invention includes a substantially cylindrical body portion extending along a longitudinal axis and having first and second ends. The body portion may be disposed about the magnet shell pole. The bobbin further includes first and second discs extending radially outwardly from the first and second ends, respectively. The first and second discs receive the coil therebetween. In a first embodiment of a bobbin in accordance with the present invention, the cylindrical body portion includes a radially inwardly extending flange and the first disc includes an axially extending projection. The flange and projection are configured to be received within openings in, or secured against surfaces of, the magnet shell of the inventive brake. In a second embodiment of a bobbin in accordance with the present invention, the first disc includes an elastically deformable retention member extending axially from the first disc. The retention member terminates in a triangular flange that is configured to engage the magnet shell of the inventive brake. The inventive coil bobbin is not restricted, however, to use within the inventive brake. Rath
Gustin David C.
Leone Michael F.
Nelson Dennis J.
Pink Todd C.
Dykema Gossett PLLC
Oberleitner Robert J.
Siconolfi Robert A.
Warner Electric Technology, Inc.
LandOfFree
Spring-set electromagnetically released brake does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Spring-set electromagnetically released brake, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spring-set electromagnetically released brake will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2598002