Patent Application
20090077783
The words “comprising,” “having,” “containing,” and “including,” and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items.
The word “shaft” means a rotating or reciprocating rod or like structure for the transmission of motive power in a mechanical device.
Mechanical devices with flush or protruding shafts frequently use an annular fluid seal surrounding an end of the shaft. A portion of the seal is seated snugly within a recess in a bearing surrounding and supporting the shaft. At the end of many shafts is a threaded cavity for a bolt used to hold an implement to this end, For example, the implement may be a sprocket, pulley, shaft coupling, shaft balancer, or other component of the mechanical device.
The seal prevents leaking of internal fluids to the exterior of the mechanical device, and such a seal needs to be periodically removed and replaced, as it hardens and breakdowns over time, ceasing to function properly, so fluid leakage occurs. These shaft fluid seals are made of a supple material, but may include a steel reinforcing ring. The internal diameter of the seal is such so that the inner annular edge of the seal presses tightly against and around the shaft forming a barrier. Nevertheless, the seal is seated and mounted in a manner that enables the shaft to move, either to rotate or reciprocate, or both.
The seal barrier prevents fluids from flowing to the exterior of the mechanical device through the interface between the shaft sidewall and the edge of the seal abutting this sidewall. Conventional removal of seals is accomplished using a metal or plastic pick. The pick is manually slid in one direction along the shaft and under the inner seal edge, catching the edge, and then pulling on the seal in the opposite direction to deform and remove the seal. Using a pick accelerates shaft wear and sometimes causes damage to the shaft, resulting in loss of sealing properties if the shaft is worn or damaged by gouging or scratching.
Our tool has one or more of the features depicted in the embodiment discussed in the section entitled “DETAILED DESCRIPTION OF ONE ILLUSTRATIVE EMBODIMENT.” The claims that follow define our tool and method of use, distinguishing them from the prior art; however, without limiting the scope of our tool and method of use as expressed by these claims, in general terms, some, but not necessarily all, of their features are:
One, the seal removal tool includes a cup element, for example, a hollow cylindrical member having first and second opposed ends. The first end is open with a circular perimeter constituting a knife-edge, and this perimeter has a diameter substantially equal to an inside diameter of an inner circular edge of the annular seal being removed. The second end has therein an enlarged threaded opening having a diameter greater than a predetermined diameter of a cavity in the face of the shaft into which a bolt is screwed to hold an implement to the shaft's end.
Two, the knife-edge may be continuous (360°) along the entire perimeter and it may be offset slightly from the shaft to avoid scoring of the shaft. The knife-edge may be barbed and configured to provide an inner and outer truncated substantially conical surfaces that meet at or near the perimeter. These surfaces are inclined from the perimeter away from each other and function as ramps that facilitate cutting and bending the seal during its removal. For example, their inclined or tapering surfaces diverge away from the perimeter, and may form a wedge portion expanding radially from the circular perimeter and slanting towards the cylinder member's second end to form the ramps. of the outer one of the truncated substantially conical surfaces. The wedge portion may terminate in a continuous, circumferential, and circular rear ledge that abuts and engages an inside surface of the seal's inner circular edge when the knife edge has deflected the seal and moved between the shaft and the seal's inner circular edge so that ledge can now grip the seal. An outer cylindrical surface portion may be immediately adjacent the perimeter and it has its axis co-extensive with a longitudinal axis of the shaft as the cylindrical member advances to cut into the seal. This outer cylindrical surface portion extends a short distance from the perimeter to an inner end
Three, a detachable advancing device for the cup element is configured to pass through the enlarged threaded opening. This advancing device may comprise a first threaded elongated rod element and a pressing element for pressing against the partially closed second end. The first rod element has a diameter that is less than the diameter of the enlarged threaded opening to enable the first rod element to pass freely through the enlarged threaded opening and be screwed into the threaded cavity in the face of the shaft's end. Thus, as the advancing device is rotated in a first direction to advance axially, the pressing element bears against the second end of the cup element to move it inward and force the knife-edge against the annular seal near the inner circular edge of the seal until the knife-edge deflects the seal and moves inward past the seal's inner circular edge and between the shaft and the inner circular edge. Rotation of the first rod element in a second direction opposite the first direction detaches it from the cylindrical member while leaving the ledge grasping the inner edge of the seal.
Four, after detaching the advancing device, a detachable extracting device is used to pull the seal off the end of the shaft. The extracting device may comprise a second threaded elongated rod element having an enlarged tip for engaging the exposed end or face of the shaft. The enlarged tip is configured to screw into the enlarged threaded opening and to advance axially and press against the exposed end or face of the shaft as the second threaded elongated rod element is rotated. This action moves the cylindrical member away from the exposed end of the shaft so the barbed knife edge, specifically the ledge, grips the seal's inner circular edge and pulls the seal away from the shaft as the second threaded elongated rod element is rotated.
Five, because of the axial alignment of the shaft, cup element, advancing device, and extracting device during seal removal, the manner in which our tool is used is almost self-explanatory and very little instruction is required to begin immediately using our tool in accordance with our method.
Our method is uniquely suited to remove a seal from an end of a shaft. A typical seal may comprise an elastomeric material having embedded therein an annular metal element having a substantially L-shaped cross-section including an annular lip member that is substantially at a right angle to a longitudinal axis of the shaft. Our method includes the steps of
(a) positioning on the end of the shaft a hollow cylindrical member having an open first end into which the end of the shaft is inserted and a second end opposite the first end, the first end having a perimeter comprising a circular knife-edge and rearward of the knife-edge a gripping member, said circular knife-edge having a diameter substantially equal to an inside diameter of the annular lip member,
(b) advancing the cylindrical member toward the seal, forcing the knife-edge to cut through the elastomeric material and bend the lip member inward until said knife-edge passes beneath the lip member so that a portion of the lip member and the gripping member engage without the cylindrical member making any substantial contact with the shaft, and
(c) extracting the cylindrical member while the portion of the lip member and the gripping member are engaged, thereby moving the cylindrical member away from the end of the shaft to pull the seal away from the shaft.
These features are not listed in any rank order nor is this list intended to be exhaustive.
One embodiment of our tool and method are discussed in detail in connection with the accompanying drawing, which is for illustrative purposes only. This drawing includes the following figures (Figs.), with like numerals indicating like parts:
Our tool may be used to remove a commonly used seal S mounted on an end 11a of a shaft 11, and it is generally designated by the number 10 (
As illustrated in
The cylindrical member 12 is made of metal such as, for example, 4140 chromoly steel, and is formed by machining a block of the metal. It has an open distal end E1 (
The knife-edge 18 is barbed and continuous along the entire perimeter P of the open end E1. As best shown in
The barbed knife-edge 18 thus includes a circumferential ramp, namely, the conical surface T2, that slopes outward, extending from a leading cutting portion of knife-edge coextensive with the perimeter P of the open end E1 and terminating at the ledge 24. The knife-edge 18, ledge 24 and ramp, or conical surface T2, may all be continuous. The knife-edge 18 and the inner wall 28 are offset slightly from the exterior sidewall SW of the shaft 11 to avoid scoring or other damage to the shaft. This offset dimension usually is substantially from 0.005 to 0.125 inch and is precisely controlled so the knife-edge 18 and inner wall 28, or any other part of the cylindrical member 12, do not touch the exterior sidewall SW of the shaft 11 in a manner that would damage the sidewall as the seal S is being removed.
The advancing device 14 may include a threaded elongated rod element R1 that extends through a washer W. As depicted in
The washer W, which functions as the pressing element, is slid over the other free end E8 of the rod element R1 and placed against the partially closed end E2. Usually after thus attaching the rod element R1 to the shaft 11 and placing the washer W on the rod element, a nut N is threaded onto the free end E8 and tightened. This free end E8 may also include a gripping structure GS2, for example a built-in hex-nut, for a gripping tool such as, for example, a wrench or pliers. This enables the rod element R1 and nut N to be rotated independent of each other so the free end E7 may be screwed into the cavity C using a wrench or pliers to grasp the gripping structure GS2 to rotated the rod element. The rod element R1 has the reduced diameter at its end E7 and a larger diameter d6 at its end E8, which are both less than the diameter d4 of the enlarged threaded opening 20, enabling the rod element to pass freely through the enlarged threaded opening and be screwed into the threaded cavity C by rotation in a first direction, for example, clockwise. Consequently, as the nut N is tightened about the rod element R1 that has been screwed into the cavity C, the washer W bears against the partially closed end E2 to move the cylindrical member 12 inward and force the knife-edge 18 to cut through the elastomeric material as depicted in
The outside diameter of the knife-edge 18, that is, its perimeter P, may be slightly less than, or slightly greater than, the inside diameter d1 of the lip member L1. If slightly greater then, the knife-edge 18 first contacts the lip member L1 and bends it inward, and then the ramp, or conical surface T2, engages the lip member and slides beneath it. If slightly less than, the knife-edge 18 first slides beneath the lip member L1 and then progressive portions of ramp, or conical surface T2, engage the lip member and bend it inward. When the entire ramp, or conical surface T2, clears the lip member L1, the lip member has enough resiliency to flex outward a sufficient distance so that a portion of the lip member grips the ledge 24 as shown in
As depicted in
After removing an attached implement from the end 11a of the shaft 11 to expose the threaded cavity C in the shaft's face 11b, the cup element or cylindrical member 12 is placed on the shaft's end. Usually the advancing rod element R1 is first screwed into the cavity C as discussed above in connection with
Our tool 10 is easy to manufacture and use, including readily available components that serve as the advancing and extracting devices. The uniquely configured cylindrical member 12 eliminates damaging of the sidewall SW of the shaft 11. Consequently, when the removed seal S is replaced, leakage is avoided. Our tool (1) essentially eliminates any damage to a sidewall of the shaft when removing the seal therefrom, (2) enables the user conveniently to access and remove seals, (3) can access a confined area, in many cases avoiding considerable disassembly of an engine, and (4) and does not damage threads of the cavity for a shaft bolt that holds an implement to the end of the shaft. Our tool is manually manipulated for easy use, and has a continuous 360 degree knife edge that may be barbed and may have a low-profile insertion ability to give maximum surface area penetration without shaft damage. The components of our tool are low cost, and simple to manufacture and assemble. With minimum instruction, a user can begin using our tool immediately. By pressing the knife edge into the seal to grasp it, the seal is manually pulled from the shaft. As this knife edge is forced into the seal, it collapses the imbedded seal steel support ring, sliding under the seal's inner edge allowing barbed portion or ledge to grip firmly this edge when pulling the seal from the seal's recess in the mechanical device.
The above presents a description of the best mode we contemplate of our tool, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains to make and use our tool. Our tool is, however, susceptible to modifications and alternate constructions from the illustrative embodiment discussed above which are fully equivalent. Consequently, it is not the intention to limit our tool to the particular embodiment disclosed. On the contrary, our intention is to cover all modifications and alternate constructions coming within the spirit and scope of our tool as generally expressed by the following claims, which particularly point out and distinctly claim the subject matter of our invention:
