Patent Publication Number: US-2016223068-A1

Title: Modularized Idler Shaft

Description:
TECHNICAL FIELD 
     This disclosure relates generally to an idler shaft assembly for machines, and, more particularly, to a idler shaft assembly having separately manufactured components coupled together to form the idler shaft assembly. 
     BACKGROUND 
     Machine engines generally include internal combustion engines, which may be that of a four-stroke, compression ignition engine and may include an engine block defining a plurality of combustion chambers or cylinders. Engines have various types (e.g., internal combustion, gas, diesel, gaseous fuel, natural gas, propane, etc.), various sizes, various number of cylinders, various types of combustion chamber (e.g., cylindrical, rotary spark ignition, compression ignition, 4-stroke and 2-stroke, etc.), and have various configurations (e.g., “V,” in-line, radial, etc.). 
     The complexity of engines requires complex manufacturing processes to manufacture conventional engine components. For example, conventional idler shaft assemblies are manufactured using costly materials (e.g., high quality steel) and complex processes. Conventional idler shaft assemblies are unitary components that provide a rigid non-concentric idler shaft that maintains center distances needed for proper meshing of gears while they transmit axial torque at a uniform constant velocity. Cheaper materials and easier manufacturing processes, while maintaining the effectiveness and reliability of the idler shaft assemblies, are desirable. 
     In some instances, such as in U.S. Patent App. Pub. No. 20090084207, titled “Split shaft for high power diesel engine,” an idler shaft assembly having a split shaft is purported to be an improved design. However, this solution and other conventional solutions require multiple gears and/or hubs within the idler shaft assemblies, thus adding complexity and potential manufacturing issues, which add to manufacturing costs. Accordingly, there is a need for improved mechanisms to reduce complexity and/or costs associated with idler shaft assemblies. 
     SUMMARY 
     In one aspect, the present disclosure discloses an idler shaft assembly that includes a ring, a shaft, and a dowel. The ring may have a ring opening defining a first axis. The shaft may be removably coupled to the ring, and the shaft may have a shaft opening defining a second axis. The dowel may be removably coupled to the shaft, and the dowel may have a third axis. The first axis, the second axis, and the third axis may be coaxial. 
     In another aspect, the present disclosure discloses a method of producing an idler shaft assembly that includes coupling a ring to a shaft, and coupling a dowel to the shaft using an interference fit. 
     In yet another aspect, the present disclosure discloses an idler shaft assembly that includes a cylindrical ring, a cylindrical shaft, a fastener, and a cylindrical dowel. The cylindrical ring may have a ring bore extending through it. The cylindrical shaft may have a shaft bore extending through it. The fastener may couple the cylindrical ring to the the cylindrical shaft through the ring bore and the shaft bore. The cylindrical dowel may be inserted into at least a portion of the shaft bore. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an engine gear train having an example idler shaft assembly in accordance with at least one embodiment of the present disclosure. 
         FIG. 2  is an exploded, perspective view of an example idler shaft assembly in accordance with at least one embodiment of the present disclosure. 
         FIG. 3  is a sectional view of an example idler shaft assembly in accordance with at least one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     It should be noted that the methods and systems described herein may be adapted to a large variety of machines. The machine may be vehicle that performs some type of operation associated with an industry such as mining, construction, farming, transportation, or any other industry known in the art. For example, the machine may be an earth-moving machine, such as an excavator, dozer, wheel loader, dump truck, backhoe, motor grader, material handler, and the like. In some examples, the machine may be a marine vehicle, a locomotive, or may be a generator. 
     Further, it should be noted that the Figures are illustrative only and they are not drawn to scale. 
       FIG. 1  is a perspective view of an engine gear train  100  having an example idler shaft assembly  112 ,  122  in accordance with at least one embodiment of the present disclosure. 
     In the context of an internal combustion engine, it is common to utilize a series of gears or a gear train  100  to power certain engine components, and to provide for a desired relative timing between the gears. The gear train  100  may include several gears, such as a driving gear, idler gears, and driven gears, used for transferring torque and speed. The gear train  100  may be used in engine applications and, according to a particular engine application, may include a crank gear  130  drivingly coupled with a cam gear  140 ,  150  through idler gears  110 ,  120 . One or more idler gears  110 ,  120  may be operably disposed between the crank and cam gears to maintain a relative timing between the two such that certain engine functions may operate efficiently. Idler shaft assemblies  112 ,  122  may be coupled to the idler gears  110 ,  120 . Idler shaft assemblies  112 ,  122  have an outer diameter that may be interference fit within an inner diameter of each idler gear  110 ,  120 . Among other functions, idler shaft assemblies  112 ,  122 , may control an offset to allow gears to freely rotate about a concentric or non-concentric shaft while transmitting torque from one gear to another. 
       FIG. 2  is an exploded, perspective view of an example idler shaft assembly  200  in accordance with at least one embodiment of the present disclosure. Idler shaft assembly  200  may include a ring  210 , a shaft  220 , and a dowel  230 . In some examples, the ring  210 , shaft  220 , and dowel  230  may be separate, independent components that may be coupled together to form the idler shaft assembly  200 . In this manner, each of the ring  210 , the shaft  220 , and the dowel  230  may be manufactured from different processes and/or or sourced from different vendors and then combined to form the idler shaft assembly  200 . In some examples, the ring  210 , the shaft  220 , and/or the dowel  230  may be manufactured from different materials. 
     The ring  210  may be cylindrical in shape, having two opposing faces having a diameter. The ring  210  may have an opening (i.e., ring opening  212  or ring bore) bored therethrough. This ring opening  212  may extend all the way through the ring  210  from one face of the ring  210  to the opposing face of the ring  210 . The ring opening  212  may define an axis. 
     In some examples, the ring  210  may be pre-hardened, non-heat-treated material, such as carbon steel, powdered metal, or other similar material. 
     Similarly, the shaft  220  may be cylindrical in shape, having two opposing faces having a diameter. The shaft&#39;s  220  diameter may be less than the ring&#39;s  210  diameter. The shaft  220  may have an opening (i.e., shaft opening  222  or shaft bore) bored therethrough. This shaft opening  222  may extend all the way through the shaft  220  from one face of the shaft  220  to the opposing face of the shaft  220 . The shaft opening  222  may define an axis. In some examples, the shaft opening  222  may have varying diameters throughout the shaft opening  222 . 
     In some examples, the shaft  220  may be heat-treated material such as carbon steel, or other similar materials that may be heat-treated up to a hardening applicable for a given application. 
     In some examples, the ring  210  and shaft  220  may be coupled together with a fastener  240  (e.g., bolt, screw, press fit dowel) that may be inserted through the ring  210  and into the shaft  220 . Some example fasteners  240  may utilize washer(s)  242 ,  244  for assisting with distributing any load placed on the fastener  240  and prohibiting oil from leaking out. In the example of  FIG. 2 , a bolt-type fastener  240  is inserted into washers  242 ,  244  prior to the fastener  240  being inserted into the ring  210  and shaft  220 . 
     The ring  210  may be coupled to the shaft  220  such that relative movement between the ring  210  and the shaft  220  is restricted or prohibited. For example, a dowel pin  250  may engage both the ring  210  and the shaft  220 . For example, the dowel pin  250  may be removably coupled to the ring  210  and also removably coupled to the shaft  220 . When the ring  210  and the shaft  220  are engaged (as depicted in  FIG. 3 ), the dowel pin  250  may engage both the ring  210  and the shaft  220  via recesses in each of the ring  210  and the shaft  220 . The dowel pin  250  may have an interference (or press) fit with the ring  210  and the shaft  220 . The dowel pin  250  may control the orientation of the ring  210  relative to the shaft  220 . 
     The dowel  230  may be cylindrical in shape, having two opposing faces. The dowel  230  may define an axis. The dowel  230  may be coupled to the face of the shaft  220  that is opposite the face of the shaft  220  that is engaging the ring  210 . In some examples, the dowel  230  may be partially inserted into the shaft opening  222  via interference (or press) fit. In this manner, the dowel  230  may effectively act as one assembly with the shaft  220 . The dowel  230  may assist in maintaining the orientation of the shaft  220  relative to other gears in the gear train. 
     In some examples, the dowel  230  may be pre-hardened, non-heat-treated material such as carbon steel, or other similar materials that may be heat-treated up to a hardening applicable for a given application. 
     When assembled, the ring opening  212 , the shaft opening  222 , and the dowel  230  may be aligned such that each of their respective axes are coaxial. However, the ring  210 , the shaft  220 , and/or the dowel  230  may not be concentric. For example, the shaft opening  222  in the shaft  220  may “off center” and the ring opening  212  in the ring  210  may be centered, thus leading the ring  210  and shaft  220  being non-concentric. 
       FIG. 3  is a sectional view of an example idler shaft assembly  300  in accordance with at least one embodiment of the present disclosure. The idler shaft assembly  300  may include a ring  310 , a shaft  320 , and a dowel  330 . The ring  310  and the shaft  320  may be coupled via a bolt  340  having washers  342 ,  344 . The bolt  340  extends through an opening in the ring  310  and into an opening in the shaft  320 . In some examples, the bolt  340  may include threads such that the bolt may extend through the opening in the ring  310  and be received by a threaded portion inside the opening in the shaft  320 . 
     The ring  310  and the shaft  320  are further coupled by the dowel pin  350  interfacing with a recess in the ring  310  and a recess in the shaft  320 . The dowel pin  350  further restricts movement of the ring  310  relative to the shaft  320 . The bolt  340  and the dowel pin  350  may cause the ring  310  and the shaft  320  to effectively act as a single component because the relative movement therebetween is restricted. 
     The dowel  330  is interference (or press) fit into the opening of the shaft  320 . In some examples, the opening of the shaft  320  may have a larger diameter where it interfaces with the dowel  330  than the diameter where it receives the bolt  340 . 
     INDUSTRIAL APPLICABILITY 
     The industrial applicability of example idler shaft assemblies described herein will be readily appreciated from the foregoing discussion. 
     The idler shaft assemblies described herein reduce the complexities of manufacturing idler shaft assemblies that currently exist. Components of idler shaft assemblies may now be manufactured separately and later assembled. In this manner, each component may be manufactured by different plants or vendors and then assembled at the factory. The distinct components of the idler shaft assemblies may also allow easier replacement of defective components at the factory prior to shipping the assembled idler shaft assembly. For example, manufacturing errors in conventional idler shaft assemblies would cause the entire assembly to be defective. The present disclosure allows for defective components to be replaced rather than the entire assembly. 
     The present disclosure&#39;s idler shaft assemblies also provide for cheaper parts costs. For example, instead of using high quality steel for an entire convention idler shaft assembly, the present disclosure teaches that components of idler shaft assemblies may be made of different materials. Certain components such as the shaft may be manufactured using high quality materials, while other components such as the ring and dowel may be manufactured using lower quality (and presumably lower priced) materials. In some examples, cost savings have been estimated between about 15-30% less than conventional idler shaft assemblies. 
     It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. 
     All methods described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.