192 clutches and power-stop control – Elements – Engaging surfaces
Reexamination Certificate
2001-01-29
2002-12-24
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Elements
Engaging surfaces
C192S066100, C192S03000R, C192S115000, C188S00111E, C188S370000
Reexamination Certificate
active
06497315
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a module adaptable to performing either a brake or clutch function. More particularly the present invention relates to the friction pad assembly of such a module and to the receptacle for holding this pad assembly wherein the receptacle and pad assembly are configured so as to permit the latter to be easily inserted into and removed from the latter. Yet more particularly, the present invention relates to such a pad assembly and receptacle mutually configured so that the pad assembly can be removed/replaced from the receptacle by hand during short down-time periods, without the need to remove any other module components. The present invention relates further to such pad assembly and receptacle wherein the latter is protected against abrasion by the former.
2. Discussion of the Prior Art
The invention described and claimed below provides a continuing improvement in the ease with which the friction pads of various brake and clutch systems can be replaced. It relates to pad-containing modules of a type that can be used, depending on the configuration of the surrounding machinery, to perform either as a brake or as a clutch. These modules are described in a number of earlier patents, including several that are assigned to the assignee of the present invention. For economy of space and time, the pad of the present invention will be described entirely in terms of its being used in a braking module, though it is to be understood that everything that is said about the present invention applies to its use in a clutch module as well. Within the field of braking, the present discussion will for convenience be even more specific, again with no intention of narrowing the understood application of the present invention.
In particular, the pad and pad receptacle of the present invention will be described in the context of their use in web-tension maintenance in those manufacturing procedures in which a series of product modifications is carried out on a continuous webbing of flexible material (“web”) as the web is conveyed along a production line. One example is the production of newsprint. Another is the imprinting of certain types of cloth. In all such operations, it is essential that the tension in the web be maintained above a certain threshold but not so high that it ruptures or otherwise damages the material making up the web. In one configuration, this tension is maintained by placing an adjustable drag on a shaft about which the flexible product is rolled and from which it feeds into the web. This drag can be imposed in a number of ways, but most commonly it involves pressing a brake pad (alternately referred to as a “brake shoe”) against a rotor coupled to the shaft; the rotor takes the form of a planar friction plate. By varying the force with which the pad is pressed against the friction plate it is possible to vary the drag and hence to vary (or maintain constant) the tension in the web coming off the shaft. In practice, there will be a number of such pads and the pad pressure on the rotor is effected through the use of an array of pneumatic- or hydraulic-activated brake modules mounted in a fixed disk—a stator—commonly referred to as a “spider.” It can be seen also that a clutch can be installed that works in a similar—though, in a sense, opposite,—fashion. That is, the pads will press against the rotor to prevent it from rotating until the web tension rises to a level exceeding the static friction force between the pads and the friction plate, at which point the friction plate will slip and the shaft will continue to rotate until the web tension once falls below sliding-friction force exerted on the friction disk by the pads.
It is advantageous to be able to change the above-described friction pads quickly and easily where they are used in production lines, where time is usually of the essence. For example, it is usually desirable to minimize the production-line down-time associated with removing and/or replacing the pads. A number of patents address the problem of quick pad replacement in brake/clutch modules. Such patents include Baynes et al. (“Disc Brake with Pocketed Quick Change Shoe Assembly,” U.S. Pat. No. 3,388,775; 1968), Klaue (“Spreading Disc Brake with Removable Shoes,” U.S. Pat. No. 3,885,650; 1975), Montalvo (“Mounting of Cylinders in Friction Brakes and Clutches,” U.S. Pat. No. 3,964,583; 1976), Yoshida et al. (“Friction Pad for Disc Brake,” U.S. Pat. No. 5,890,566; 1999), Demetriou et al. (“Air Disc Brake,” U.S. Pat. No. 5,671,827; 1997), Le Deit et al. (“Assembly Comprising a Friction Pad . . . ,” U.S. Pat. No. 5,662,191; 1997), Chuang et al. (“Friction Pad For A Disk Brake,” U.S. Pat. No. 5,617,935).
Most closely related to the specific nature of the present invention are Montalvo et al. (U.S. Pat. No. 5,178,235; 1993) [hereinafter Montalvo I] and Montalvo et al. (U.S. Pat. No. 5,868,233; 1999) [hereinafter Montalvo II, which is further referenced in application Ser. No. 09/542,639 seeking reissue of Montalvo II]. Both of the last-named patents are assigned to the assignee of the present invention; they describe the particular nature of the modules to which the present invention is directed. They are to be understood to be incorporated into the present discussion.
The spider in which the brake modules are to be mounted is in general a metallic disc thick enough to give it rigidity against the torsional forces exerted on it during the braking process. Distributed around the circumference of the spider, generally equally spaced, are holes, each adapted to receive one of the brake modules. The spider is affixed to a base that is itself floor-mounted. The friction disc (the rotor) is affixed to the roll. Typically, the spider is interposed between the roll and the friction disc. In such a configuration, a shaft coupled to the roll rests on a bushing in the center of the spider, with a portion of the shaft extending to the outboard side of the spider. It is to the outboard end of the shaft that the friction disc is rigidly affixed. The friction disc plane is parallel to that of the spider and both are substantially vertical. Because the brake modules are around the full 360 degrees of the spider, some means must be used to prevent the pad assemblies from falling out of the modules due to gravitational forces.
In addition to gravitational forces, the pad assemblies are exposed to the much greater force resulting from the braking action itself. When the pads are pressed against the rotating friction disc the resulting frictional force tends to carry the pad around with the friction disc. To resist this torsional force “torque resistors” are placed adjacent to the pad assemblies. In the earlier designs described in the prior art such as Montalvo I, these torque resistors were referred to as “torque posts,” since they were circular in cross-section; the pad assembly had semi-circular openings on its perimeter, one on the distal extremity and a matching one on the proximal extremity, through which torque posts passed when the pad assembly was installed in the module. (As used throughout this discussion, “distal” refers to the direction toward the center of the spider and “proximal” refers to the direction away from the center, that is toward the perimeter of the spider. Similarly, with respect to a component, the end of the component intended to be closer to the spider center is the distal end of that component and conversely with respect to its proximal end.) These torque posts prevented the pads from rotating under the torque transmitted to them from the friction plane. They also prevented the pads from moving out radially from the axis of the spider. However, this arrangement required a removal of the proximal post before one could withdraw a pad assembly. Once that post was removed, the pad assembly could be slid along the line between the erstwhile positions of the two torque posts—a line substantially parallel to one of the radii of the spider—and hence remo
Bohan Thomas L.
Mathers Patricia M.
Rodriguez Saul
The Montalvo Corporation
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