Claims:CLAIMS

1. A worm speed reducer, comprising:
a worm coupled to an electric motor;
a worm wheel comprising a plurality of teeth and configured to drive an output load; wherein a first portion of the plurality of teeth are operatively coupled to the worm; and
a plurality of fasteners configured to mechanically couple the worm wheel to an output load; and wherein upon unbolting the plurality of fasteners, the worm wheel is separated both from the worm and the output load.

2. The worm speed reducer of claim 1, wherein a number of the plurality of fasteners is a based on a rotation range of the output load.

3. The worm speed reducer of claim 1, wherein the worm wheel is reusable by dismounting and rotating the worm wheel to operatively couple a second porting of the plurality of teeth with the worm.

4. The worm speed reducer of claim 3, wherein a reusability of the worm wheel is based on a rotation range of the output load.
, Description:BACKGROUND
[001] This invention relates to speed reducers and more particularly to a field replaceable worm wheel for a worm speed reducer.
[002] In several power systems, rotation output from an electric motor, for example, is transmitted to a worm of a worm speed reducer. In most assemblies, the speed of a rotation output from the electric motor is reduced using a worm speed reducer which includes a worm wheel that meshes with the worm. The reducer reduces the high speed of a motor connected to its input to a low speed of a load connected to its output.
[003] Typically, the worm speed reducer includes a hard metal (usually steel) worm and softer metal (usually bronze) wheel pair for speed reduction. The life of speed reducers formed of such assemblies however is limited by the life of the bronze wheel. Wear is higher in worm speed reducers as compared to other types of speed reducers due to sliding friction as opposed to rolling friction. Hence worm speed reducers are usually not used in applications with very long life requirements. In addition, since the life of the speed reducer is dependent on the load, it can vary widely based on actual usage.
[004] Due to a limited life of the worm wheel, it is often required to be replaced. However, the current design of worm speed reducers requires the entire speed reducer assembly to be disassembled before the worm wheel can be replaced. This process is very laborious and requires tooling and resources that cannot be taken to the field for replacement at point of use.
[005] Further in many applications, it is seen that the range of rotation of the worm wheel is less than its full revolution, i.e., only the teeth in the wheel in the range of rotation are subjected to use and consequent wear. By reassembling the wheel to engage the unused teeth the life of the speed reducer can be doubled.
[006] Therefore, there is a need for a replaceable worm wheel for a speed reducer which is durable as well as cost effective, and which can be easily reassembled or replaced in the field without the need of special tools and/or resources.
BRIEF DESCRIPTION
[007] Briefly, according to one aspect of the present technique, a worm speed reducer is provided. The worm speed reducer comprises a worm coupled to an electric motor and a worm wheel configured to drive an output load. The worm wheel includes a plurality of teeth which are operatively coupled to the worm. The worm speed reducer further includes a plurality of fasteners mechanically coupling the worm wheel to the output load. Upon unbolting the plurality of fasteners, the worm wheel is separated both from the worm and the output load.

BRIEF DESCRIPTION OF FIGURES
[008] This invention is illustrated in the accompanying drawings, in which like reference letters/numerals indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[009] FIG. 1 is a perspective view of one embodiment of a speed reducer assembly implemented according to aspects of the present technique;
[0010] FIG. 2, FIG. 3 and FIG. 4 are perspective views illustrating a manner in which a field replaceable worm wheel is separated from a speed reducer assembly;
[0011] FIG. 5 is a cross-sectional view illustrating an engagement in which a field replaceable worm wheel is engaged with worm of the speed reducer assembly of FIG. 1; and
[0012] FIG. 6 is a front view of an embodiment of a field replaceable worm wheel implemented according to aspects of the present technique.

DETAILED DESCRIPTION OF INVENTION
[0013] The drawings are to be regarded as being schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be implemented by an indirect connection or coupling.
[0014] Various example embodiments will now be described more fully with reference to the accompanying drawings in which only some example embodiments are shown. Specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Example embodiments, however, may be embodied in many alternate forms and should not be construed as limited to only the example embodiments set forth herein.
[0015] Accordingly, while example embodiments are capable of various modifications and alternative forms, example embodiments are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed. On the contrary, example embodiments are to cover all modifications, equivalents, and alternatives thereof. Like numbers refer to like elements throughout the description of the figures.
[0016] FIG. 1 is a schematic diagram illustrating an embodiment of a speed reducer assembly 1 implemented according to an aspect of the present invention. The worm speed reducer 1 includes a worm 2, a replaceable worm wheel 3, a plurality of fasteners 7 and a supporting structure 4. Each component is described in further detail below.
[0017] Worm 2 is driven by an electric motor (not shown) and is configured to operate with the worm wheel 3 to control a speed of the output load (not shown). Worm 2 includes a plurality of threads 6. The worm 2 is configured to rotate continuously while driving the load.
[0018] Worm wheel 3 is operatively coupled to the worm 2 and includes a plurality of teeth 5. During operation, the plurality of teeth 5 of the worm wheel 3 engages with the plurality of threads 6 of the worm 2. The combined motion of the worm wheel 3 and the worm 2 translates to a reduced speed of the motor. In one embodiment, for each complete turn of the worm 2, the worm wheel 3 advances by only one tooth.
[0019] The worm wheel 3 is also mechanically coupled to the output flange 9 using a plurality of fasteners 7. The worm wheel 3 is separated from the output flange 9 simply by unbolting the plurality of fasteners 7. This ensures that the worm speed reducer assembly 1 need to not be disassembled to replace the worm wheel. Instead, by simply unbolting the fasteners 7, the worm wheel 3 may be easily removed and replaced on-site.
[0020] Further, the replaceable worm wheel 3 is also reusable. Reusability is achieved by simply separating the worm wheel 3 from the speed reducer assembly 1 and turning the worm wheel to engage a second portion of the teeth with the worm. The manner in which the replaceable wheel may be replaced and/or reused is described in further detail below.
[0021] FIG. 2, FIG. 3 and FIG. 4 illustrates the various steps involved in separating the field replaceable worm wheel 3 from the worm speed reducer 1. As described with reference to FIG. 1, the plurality of fasteners 7 is configured to mechanical couple the worm wheel 3 to the output load. In one embodiment, the plurality of fasteners 7-A through 7-D may differ from each other in terms of shape. Further, the worm wheel 3 is disengaged from the worm 2 by unbolting the fasteners 7-A through 7-D as shown in FIG.2.
[0022] As shown FIG. 3, upon unbolting of fasteners 7, the worm is first moved in a downward direction (perpendicular to the horizontal axis 8 of the worm wheel) as indicated by arrow 10. The worm wheel 3 is first moved downward in order to disengage the plurality of teeth of worm wheel from the plurality of threads 6 of the worm 2 as shown by arrow 10.
[0023] As can be seen in FIG. 5, the worm wheel 3 is moved first in the downward direction to disengage the teeth from the threads. Further, upon disengaging the worm wheel 3 from the worm 2, the worm wheel is then moved in the horizontal direction 11 (parallel to the horizontal axis 8 of the worm wheel) to completely separate from the output load as shown in FIG 4.
[0024] Thus, by unbolting the fasteners 7-A through 7-D, the worm wheel may be mechanically separated from the output – first by moving downward to disengage from the worm and then moving horizontally to separate from the output load. As described earlier, the replaceable worm wheel can also be reused. The manner in which the worm wheel is reused is described in further detail below.
[0025] FIG. 6 is a front view of an embodiment of a worm wheel 12 implemented according to aspects of the present technique. The worm wheel 12 comprises a plurality of teeth 13 that is configured to operatively engage with a worm (not shown). The manner in which the worm wheel may be reused is described in further detail below.
[0026] During operation, a first portion of the plurality of teeth 14 engages with the worm to obtain a desired reduction in speed. A magnitude of the first portion of teeth 14 is based on an output rotation range of the load. For example, if the output rotation range is less than 180 degrees, the first portion 14 is half the number of teeth on the worm wheel.
[0027] Upon wear and tear of the first portion of the plurality of teeth 14, the worm wheel is first removed from the worm speed reducer (as described in FIG. 2 through FIG. 4). Once separated, the worm wheel is rotated by 180 degrees and then mounted back on the worm speed reducer by bolting the fasteners. The worm wheel 12 is rotated such that a second portion of the plurality of teeth 15 is now engaged with the worm. Thus, by reusing the worm wheel the life of the worm wheel reducer is extended.
[0028] The above described invention has many advantages including the ability to replace the worm wheel on-site without the need to disassemble the entire speed reducer assembly thus making it very efficient and cost-effective. Further, since the worm wheel may be reused (based on the output rotation range of the load), a life of the worm wheel is extended.
[0029] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present.
[0030] For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations).
[0031] While only certain features of several embodiments have been illustrated, and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of inventive concepts.
[0032] The aforementioned description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure may be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the example embodiments is described above as having certain features, any one or more of those features described with respect to any example embodiment of the disclosure may be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described example embodiments are not mutually exclusive, and permutations of one or more example embodiments with one another remain within the scope of this disclosure.