Dual Concentric Drive Method and Apparatus

Abstract

A dual bushing and hub assembly for mounting sheaves, sprockets, gears, couplings and similar machine elements on a shaft, wherein two types of tapered bushings are used, the bushings are used within a single hub which is compatible with both bushings. The dual bushing locking screws for tightening the bushings securely in place on the shaft and in the hub bore are both accessible from the same side of the hub.

Claims

1. A dual concentric drive apparatus for coupling a first shaft having a first shaft diameter and a second shaft having a second shaft diameter to a hub, the apparatus comprising: the hub comprising; a first interior bore comprising a first taper angle .sub.1 and a first hub bore diameter; a second interior bore comprising a common axis with the first interior bore and comprising a second taper angle .sub.2 and a second hub bore diameter smaller than the first hub bore diameter; an interior first hub short slot facing on the first interior bore; an interior first hub threaded long slot facing on the first interior bore and opposite to the interior first hub short slot; an interior second hub short slot facing on the second interior bore; and an interior second hub threaded long slot facing on the second interior bore and opposite to the interior second hub short slot.

2. The dual concentric drive apparatus as in claim 1 further comprising a first tapered split bushing having a first bushing bore, wherein the first tapered split bushing comprises: the first hub bore diameter the first taper angle .sub.1; a first inner bore comprising a first inner diameter for receiving the first shaft and maintaining a friction holding force between the first tapered bushing and the first shaft; a first tapered bushing threaded slot having a long dimension parallel to the first bushing bore for matching the first hub short slot thereby defining a first opening for receiving a first set screw from a first direction; and a first tapered bushing short slot opposite the first tapered bushing threaded slot for matching the interior first hub threaded long slot thereby defining a second opening for receiving the first set screw from the first direction.

3. The dual concentric drive apparatus as in claim 2 further comprising the first opening having a first opening diameter and the second opening having a second opening diameter, wherein the second opening diameter is less than the first opening diameter.

4. The dual concentric drive apparatus as in claim 1 further comprising a second tapered split bushing having a second bushing bore, wherein the second tapered split, bushing, comprises: the second hub bore diameter the second taper angle .sub.2; a second inner bore comprising a second inner diameter for receiving the second shaft and maintaining a friction holding force between the second tapered bushing and the second shaft; a second tapered bushing threaded slot having a long dimension parallel to the second bushing bore for matching the second hub short slot thereby defining a third opening for receiving a second set screw from the first direction; and a second tapered bushing short slot opposite the second tapered bushing threaded slot for matching the interior second hub threaded long slot thereby defining a fourth opening for receiving the second set screw from the first direction.

5. The dual concentric drive apparatus as in claim 4 further comprising the third opening having a third opening diameter and the fourth opening having a fourth opening diameter, wherein the fourth opening diameter is less than the first opening diameter.

6. A method for coupling a first shaft and a second shaft to a common hub having a coaxial first central bore and a second central bore, the method comprising: providing a first split bushing having a first interior bore for surrounding the first shaft, and a tapered non-grooved external surface for transferring torque to the hub entirely by friction inside the first central bore, and one first exterior slot in a direction parallel to the first interior bore for matching a first threaded slot in the hub, thereby defining an opening for receiving a first set screw from a first direction; driving the first set screw into the matched first exterior slot and the first threaded slot such as to draw the first split bushing into the first central bore of the hub, thereby coupling the first shaft to the hub; providing a second split bushing having a second interior bore for surrounding the second shaft, and a tapered non-grooved external surface for transferring torque to the hub entirely by friction inside the second central bore, and one second exterior slot in a direction parallel to the second interior bore for matching a second threaded slot in the hub, thereby defining an opening for receiving a second set screw from the first direction; and driving the second set screw into the matched second exterior slot and the second threaded slot from the first direction such as to draw the second split bushing into the second central bore of the hub, thereby coupling the second shaft to the hub.

7. The method as in claim 6 further comprising decoupling the first shaft from the common hub, the method comprising: providing the first split bushing with an exterior threaded slot in a direction parallel to the first interior bore and opposite the first exterior slot for matching a non-threaded slot in the hub, thereby defining an opening for receiving the first set screw from the first direction; and driving the first set screw into the matched exterior threaded slot and the non-threaded slot from the first direction such as to draw the first split bushing out of the first central bore of the hub, thereby decoupling the first shaft from the hub.

8. The method as in claim 6 further comprising decoupling the second shaft from the common hub, the method comprising: providing the second split bushing with an exterior threaded slot in a direction parallel to the second interior bore and opposite the second exterior slot for matching a non-threaded slot in the hub, thereby defining an opening for receiving the second set screw from the first direction; and driving the second set screw into the matched exterior threaded slot and the non threaded slot from the first direction such as to draw the second split bushing out of the second central bore of the hub, thereby decoupling the second shaft from the hub.

9. A dual concentric drive apparatus for coupling a first shaft having a first shaft diameter and a second shaft having a second shaft diameter to a hub, the apparatus comprising: the hub comprising; a first interior bore comprising a first taper angle .sub.1 and a first hub bore diameter; a second interior bore comprising a common axis with the first interior bore and comprising a second taper angle .sub.2 and a second hub bore diameter smaller than the first hub bore diameter; an interior first hub short slot facing, on the first interior bore; an interior first hub threaded long slot facing on the first interior bore and opposite to the interior first hub short slot; an interior second hub short slot facing on the second interior bore; and an interior second hub threaded long slot facing on the second interior bore and opposite to the interior second hub short slot. a first tapered split bushing having a first bushing bore, wherein the first tapered split bushing comprises: the first hub bore diameter the first taper angle .sub.1; a first inner bore comprising a first, inner diameter for receiving the first shaft and maintaining a friction holding force between the first tapered bushing and the first shaft; a first tapered bushing threaded slot having a long dimension parallel to the first bushing bore for matching the first hub short slot thereby defining a first opening for receiving a first set screw from a first direction; and a first tapered bushing short slot opposite the first tapered bushing threaded slot for matching the interior first hub threaded long slot thereby defining a second opening for receiving the first set screw from the first direction. a second tapered split bushing having a second bushing bore, wherein the second tapered split bushing comprises: the second hub bore diameter the second taper angle .sub.2; a second inner bore comprising a second inner diameter for receiving the second shaft and maintaining a friction holding force between the second tapered bushing and the second shaft; a second tapered bushing threaded slot having a long dimension parallel to the second bushing bore for matching the second hub short slot thereby defining a third opening for receiving a second set screw from the first direction; and a second tapered bushing short slot opposite the second tapered bushing threaded slot for matching the interior second hub threaded long slot thereby defining a fourth opening for receiving the second set screw from the first direction.

10. The dual concentric drive apparatus as in claim 9 wherein the first inner bore is not tapered.

11. The dual concentric drive apparatus as in claim 9 wherein the second inner bore is not tapered.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The subject matter which is, regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0016] FIG. 1 is a side elevational view of a shaft/sprocket coupling employing a prior art bushing;

[0017] FIG. 2 is a cross-sectional of the prior art shaft/sprocket coupling of FIG. 1, the section being taken along line 2-2 of FIG. 1;

[0018] FIG. 3 is a top perspective view of the dual concentric drive apparatus in accordance with the present invention;

[0019] FIG. 4 is an exploded view of the dual concentric drive apparatus in accordance with the present invention shown in FIG. 1;

[0020] FIG. 5A, FIG. 6A, FIG. 7A are top perspective views of the dual concentric drive apparatus components shown in FIG. 4 and illustrate features of the present invention shown in FIG. 1;

[0021] FIG. 5B, FIG. 6B, FIG. 7B are top perspective views of the dual concentric drive apparatus components shown in FIG. 4 and illustrate features of the present invention shown in FIG. 1;

[0022] FIG. 8 is a cross-sectional view of the dual concentric hub in accordance with the present invention shown in FIG. 1;

[0023] FIG. 9 is a top view of the dual concentric hub in accordance with the present invention shown in FIG. 1; and

[0024] FIG. 10 is a bottom view of the dual concentric hub in accordance with the present invention shown in FIG. 1.

DETAILED DESCRIPTION

[0025] The following brief definition of terms shall apply throughout the application:

[0026] The term comprising means including but not limited to, and should be interpreted in the manner it is typically used in the patent context;

[0027] The phrases in one embodiment, according to one embodiment, and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment);

[0028] Dual concentric bushing hub assembly may be referred to as dual concentric drive apparatus.

[0029] If the specification describes something as exemplary or an example, it should be understood that refers to a nonexclusive example; and

[0030] If the specification states a component or feature may, can, could, should, preferably, possibly, typically, optionally, for example, or might (or other such language) be included or have a characteristic, that particular component or feature is not required to be included or to have the characteristic.

[0031] In precision position and motion control applications, considerations driving the design of shaft/sprocket couplings may be other than those of maximizing torque, as in the prior art power transmission applications, and, more particularly, may include the precision concentricity of the shaft and sprocket rotation axes and convenience of assembly and disassembly in tight spaces. Precision concentricity may be required to prevent wobble of the driven components and the wear and noise that may result from imperfect balance. Additionally, in motion control applications, it may be desirable to phase or synchronize various elements of a drive train independently of shaft position. Such phasing may be advantageously accomplished in accordance with certain embodiments of the present invention.

[0032] Referring to FIG. 3 there is shown a top perspective view of the dual concentric drive apparatus in accordance with the present invention. Hub 46 with the features described herein may be the hub of any suitable drive mechanism such as a sprocket, pulley, or gear. Bushing 42 is an externally tapered split bushing having an non-tapered bore 31 in accordance with the present invention. Bushing 42 has slit or unthreaded groove 51 which is aligned with slit or threaded groove 72 in hub 46 and forms an opening for driving a set screw (not shown) into said opening for drawing the bushing 42 into hub 46 and frictionally engaging a shaft (not shown) in the non-tapered bore 31.

[0033] Still referring to FIG. 3, Bushing 42 has slit or threaded groove 52 which is aligned with slit or non-threaded groove 74 in hub 46 and forms an opening for driving a set screw, often referred to as a jack screw, (not shown) into said opening for drawing the bushing 42 out of hub 46 and disengaging the shaft (not shown) from the non-tapered bore 31. It will be appreciated that threaded groove 52 is along the split 52A, of split bushing 42 facilitating the decoupling of bushing 42 from said shaft and hub 46.

[0034] Referring also to FIG. 4 there is shown an exploded view of the dual concentric drive apparatus in accordance with the present invention shown in FIG. 1. Bushing 42, shown in FIG. 3, is a split bushing have an outside diameter od1, an external taper .sub.1, and a non-tapered bore hole 31 having a diameter sd1a. Bushing 44 is a split bushing have an outside diameter od2, an external taper .sub.2, and a non-tapered bore hole 32 having a diameter sd2a. Hub 46 has a first bore having an internal diameter hd1 for receiving, bushing 42. As will be described later hub 46 also includes a second bore, coaxial with the first bore, for receiving bushing 44. It will be appreciated that bushing 44 od2 is less than bushing od1.

[0035] Referring also to FIG. 5A, FIG. 6A, FIG. 7A there shown top perspective views of the dual concentric drive apparatus components shown in FIG. 4 and illustrate features of the present, invention shown in FIG. 1.

[0036] Bushing 42 is a tapered split bushing having a long dimension or groove 52 parallel to the interior bore 31. Groove 52 is split 52a along the entire dimension and threaded 52b. Bushing 42 also includes non-tapered bore 31. Exterior surface 42a may be treated, as by plating, so as to have distinct surface properties from the surface properties of the hub 46 into which bushing 42 is inserted, thereby advantageously reducing the propensity of the bushing to bind upon insertion. Additionally, bushing 42 may be fabricated of a material, such as a metal or a plastic, differing in composition from the material of the hub 46 so as to reduce the propensity of the bushing 42 to bind upon insertion into the hub 46.

[0037] Bushing 42 has slit or unthreaded groove 51 which is aligned with slit or threaded groove 72 in hub 46 and forms an opening for driving a set screw (not shown) into said opening for drawing the bushing 42 into hub 46 and frictionally engaging a shaft (not shown) in the non-tapered bore 31.

[0038] Bushing 44 is a tapered split bushing, having a long dimension or groove 62 parallel to the interior bore 32. Groove 62 is split 62a along the entire dimension and threaded 62b. Bushing 44 also includes non-tapered bore 32. Exterior surface 44a may be treated, as by plating, so as to have distinct surface properties from the surface properties of the hub 46 into which bushing 44 is inserted, thereby advantageously reducing the propensity of the bushing to bind upon insertion. Additionally, bushing 44 may be fabricated of a material, such as a metal or a plastic, differing in composition from the material of the hub 46 so as to reduce the propensity of the bushing 44 to bind upon insertion into the hub 46.

[0039] Additionally bushing 44 has slit or unthreaded groove 61 which is aligned with slit or threaded groove 71 in hub 46 and forms an opening for driving a set screw (not shown) into said opening for drawing the bushing 44 into hub 46 and frictionally engaging a second shaft (not shown) in the non-tapered bore 32.

[0040] Hub 46 is a dual, coaxial bore, hub. The bores are sized and tapered to receive bushings 42, 44. Additionally, hub 46 may be fabricated of a material, such as a metal or a plastic, differing in composition from the material of the bushings 42,44 so as to reduce the propensity of the bushings 42, 44 to bind upon insertion into the hub 46.

[0041] Referring also to FIG. SB, FIG. 6B, and FIG. 7B there are shown top perspective views of the dual concentric drive apparatus components shown in FIG. 4 and illustrate features of the present invention shown in FIG. 1. Bushings 42 and 44 each include non-threaded slots or grooves 51, 61 for mating with the hub threaded grooves 72, 71 (see FIG. 7A), respectively. It will be appreciated that the non-threaded grooves 51,61 do not extend the length of the bushings and include a termination shelf 5b1, 6b1 for the set screws (not shown) to push against when drawing the bushings into the hub 46.

[0042] Hub 46 includes non-threaded slots or grooves 74, 76 for mating with the bushing threaded grooves 52, 62 (see FIGS. 5A, 6A), respectively. It will be appreciated that the non-threaded grooves 74, 76 do not extend the length of the hub and include a termination shelf 7b1,7b2 for the jack screws (not shown) to push against when drawing the bushings out of the hub 46. Also shown in FIG. 7B is shelf 73 indicating where the second bore begins.

[0043] Referring also to FIG. 8 there is shown a cross-sectional view of the hub 46 in accordance with the present invention shown in FIG. 1. Hub 46 includes dual coaxial bores 81, 82. Bore 81 includes diameters od1a, od1b at either end of the bore 81 describing a taper and diameter sized to receive split tapered bushing 42. Bore 82 includes diameters od2a, od2b at either end of the bore 82 describing a taper and diameter sized to receive split tapered bushing 44.

[0044] Referring also to FIG. 9 there is shown a top view of the dual concentric bushing hub assembly 10 in accordance with the present invention shown in FIG. 1.

[0045] Referring also to FIG. 10 there is shown a bottom view of the dual concentric bushing hub in accordance with the present invention shown in FIG. 1.

[0046] It should be understood that the foregoing description is only illustrative of the invention. Thus, various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances that fall within the scope of the appended claims.