Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H48/00—Differential gearings
  • F16H48/20—Arrangements for suppressing or influencing the differential action, e.g. locking devices
  • F16H48/28—Arrangements for suppressing or influencing the differential action, e.g. locking devices using self-locking gears or self-braking gears
  • F16H48/29—Arrangements for suppressing or influencing the differential action, e.g. locking devices using self-locking gears or self-braking gears with self-braking intermeshing gears having perpendicular arranged axes and having worms or helical teeth

Definitions

• the present invention relates generally to differ- ential mechanisms and in particular to a new and im ⁇ proved differential case for use with a cross axis com ⁇ pound planetary gear differential assembly.
• Patent No. 2,859,641 to Gleasman which is hereby incorporated by reference discloses a worm gear differ ⁇ ential mechanism, termed a "cross-axis compound planet ⁇ ary gear complex".
• the disclosed differential includes a differential case that mounts gear elements which couple rotation of the differential case to axles extending into the case.
• a pair of axle drive gears also termed traction or side gears
• Pairs of balancing gears are mounted in windows disposed in the case and split driving torque between the side gears.
• the differential case is actually an assembly held together by spacer bolts and other fasteners.
• the differential case assembly includes three windows.
• the differential disclosed in this Gleasman patent, operates extremely well, it is nevertheless desirable to reduce its manufacturing cost. Some attempts have been made to reduce the cost of this differential. One such attempt included the substitution of a one piece casting for the individua l components that made up the original differentia l
• a new and improved differential is disclosed which includes an integral differential case that sim ⁇ plifies the construction and assembly of the differ- ential and significantly reduces its manufacturing cost.
• the present invention also encompasses a process for making the case and in particular includes a process for finishing the requisite machined surfaces that coact with or locate the gear components in the diff- erential assembly.
• the differ ⁇ ential case is a unitary casting and comprises end portions disposed on either side of an intermediate portion.
• One end portion defines a ring gear mounting flange and a laterally extending trunnion disposed centrally with respect to the flange.
• the trunnion includes an axle receiving bore through which an axle is inserted to engage internal gear components supported within the differential case.
• the other end portion includes another laterally extending trunnion which also includes an axle receiving bore.
• the trunnions are adapted to receive bearings by which the differential case is rotatably mounted to a differential housing.
• the trunnions define an axis of rotation for the case 5 which is typically coincident with the central axis of the ring gear mounting flange.
• the intermediate portion of the differential case defines spaced apart, aligned peripheral openings, which for purposes of explanation 10 are termed "transfer gear windows".
• a common centerline through the windows intersects the axis of rotation for the differential case.
• Each transfer gear window is defined by a pair of spaced apart, preferably parallel side walls and a pair r- of spaced apart transverse window wall sections that extend between and merge with the side walls .
• each transverse window wall section defines a machined surface that serves as a locating and reaction surface for transfer gears 0 mounted within the window. The machined surface of each window wall section projects outwardly from and towards a center plane of the window, so that other portions of the window wall section are disposed in a plane spaced further from the center plane than the 5 plane of the machined surf ces.
• the amount of finish machining for a transfer gear window is reduced.
• only the locating/reaction surfaces for the transfer gears are actually finish ° machined; the remainder of the wall sections and side walls defining the window opening are left unmachined.
• each end portion includes an annular extension, that extends inwardly into the inside of the differential case.
• the 5 annular extensions are preferably formed concentric
• each extension defines a locating and reaction surface for an axle drive gear or axle drive gear bearings, disposed within the differential. 5 The reaction surface for each extention is defined by a machined end face.
• the distance between the end faces of the extensions is less than the distance between the side walls of
• the window openings When viewed from a window, the extensions appear to project towards the center line of the windows and are disposed in parallel planes that are orthogonal to the planes of the machined surf ces of the window wall sections.
• the extensions When viewed from a window, the extensions appear to project towards the center line of the windows and are disposed in parallel planes that are orthogonal to the planes of the machined surf ces of the window wall sections.
• a broaching tool is inserted through a window opening to finish machine the projecting surfaces of the window wall sections and the end faces of the inner extensions of the case end portions.
• broached window surfaces and broached extension end faces for the transfer gears and axle drive gears, respectively, are provided in a single broaching cycle.
• the added clearance provided by the unmachined portions of the windows provide chip 5 relief for the broaching process.
• the intermediate portion defines additional openings that are positioned substantially 90 degrees from the transfer gear windows.
• the intermediate portion defines recesses between
• each post defines shaft receiving bores aligned with associated bores on the adjacent L-shaped posts which together support shafts by which transfer gears are rotatably carried within the window.
• Each post preferably includes a means for retaining the shafts which in the preferred embodiment comprises relatively small diameter bores for receiving a retaining pin or similar arrangement.
• the construction of the differential case is disclosed for use with a cross axis compound planet ⁇ ary gear differential of the type described in Gleasman Patent No. 2,859,641, but in which two pairs of bal ⁇ ancing gears are used to cross couple the axle drive gears instead of three pairs as disclosed in the Gleasman patent.
• the unitary case reduces assembly time of the differential and even more importantly, the cost of producing the case is substantially less than the cost of producing a differential case comprised of individual components.
• Figure 1 is a sectional view of a differential case embodying the present invention as seen from the plane indicated by the line 1-1 in Figure 2;
• Figure 2 is an end view of the differential case
• Figure 3 is a side elevational view of the differ ⁇ ential case, rotated 90 degrees from the position shown in Figure 1;
• Figure 4 is a sectional view of the case as seen from the plane indicated by the line 4-4 in Figure 3.
• a differential case 110 constructed in accordance with the preferred embodiment of the invention is illustrated in Figures 1-3
• the case comprises end portions 110a, 110b disposed on either side of an intermediate portion 110c.
• the three case portions comprise an integral casting.
• the left end portion 110a (as viewed in Figure 1) includes a trunnion 112 formed by a machined annulus which is adapted to receive a bearing by which the trunnion, and hence the differential case, is rotat- ably mounted to a differential housing.
• the trunnion 112 defines an internal, axle receiving bore 114 that extends through the trunnion and opens into the interior of the differential case.
• the end portion 110a also includes a flange 118 including a plurality of apertures 118a by which a ring gear (not shown) is mounted to the differential case.
• the right end portion 110b (as viewed in Figure 1) includes a trunnion 126 that also defines, at least partially, an internal axle receiving bore 128 that opens into the interior of the case.
• the trunnion 126 also comprises a machined annulus adapted to receive a bearing by which the right end of the differ ⁇ ential case is rotatably mounted to a differential housing.
• the trunnions 114, 126 and ring gear flange 118 define an axis of rotation 20 for the differential case.
• unmachined portions of the trunnion hub, indicated by the reference charac ⁇ ter 130 include relief notches 132, spaced 180 degrees apart, to provide access for a bearing removing tool should re p lacement of a differential bearing be necessary.
• the end portion 110b includes similar notches or reliefs (not shown).
• the intermediate portion 110c defines spaced apart, aligned openings, 140 which for purposes of explanation will be termed "windows", in which gear components are located and carried. As seen in Figure 1, the openings appear to define a through-passage 150 extending through the intermediate portion 110c of the differential case.
• each window is defined by vertical, preferably unmachined, walls 152 and spaced apart, transverse walls 154 which preferably include unmachined portions 154a on either side of a machined portion 154b.
• the intermediate portion 110c also includes an additional pair of openings 156 (shown in Figures 3 and 4) which are rotated 90 degrees with respect to the windows 140.
• the intermediate portion 110c also includes recesses or relieved areas 158 between the windows 140 and the openings 156 so that, in section, and as seen in Figure 4, the intermediate section appears to comprise four L-shaped posts which, for purposes of explanation, shall be individually desig ⁇ nated by the reference character 160.
• Each post defines a pair of parallel, through bores 166 that extend from the recess 158 and open into an associated window 140 and also includes a pair of smaller diameter bores 168 oriented 90 degrees with respect to the bores 166, which extend from the recess 158 to the differential case openings 156.
• the bores 166 of the posts 160 are machined or formed in alignment with each other for the purpose of receiving shafts 170 by which transfer gears 172 (only one shaft and one gear are shown) are rotatably carried within the window 140.
• the smaller diameter bores 168 receive shaft retainers 174, such as friction pins to maintain the transfer gear shafts 170 in position.
• locating- and reac ⁇ tion (thrust receiving) surfaces for axle drive gears 176 are provided b y respective annular, inwardly extending extensions 180.- 182 of the end portions 110a, 110b.
• the annular extensions 180, 182 are preferably formed concentric with respective axle receiving bores 114, 128 and as seen in Figure 1, the extensions define machined end faces which abuttably engage an outer end face 176a of the side gears 176 or, alternately, the side of a thrust bearing disposed between the side gear 176 and the extension 180 (not shown) .
• the transverse dimension of the windows (the distance between the window walls 152) , as indicated by the arrow 186, is greater than the distance between the internal end faces of the extensions 180, as indicated by the arrow 188.
• the machined surface portions 154b of the transverse window wall sections 154 extend inwardly towards a center plane of the window 140, parallel to a v/indow centerline 178 (shown in Figure 4), whereas the extensions 180, 182 project towards the centerline, the end faces being disposed in parallel planes that are ortho ⁇ gonal to the planes of the machined surface portions 154b of the windows.
• the finished surfaces are formed by a broaching process.
• a broaching tool By appropriate design and construction of a broaching tool the machined portions 154b of the window walls 154 as well as the end faces of the extensions 180, 182 can be finish machined in one broach cutting cycle.
• only those differential case surfaces, requiring a machine finish, are actually contacte d b y t h e broach.
• the amount of material remove d during the broaching process is reduced an d , in a dd ition,
• one or both windows 140 may be finish machined in a single broaching cycle depending on the broach construction.
• the use of a broaching process to manufacture the disclosed diff- erential case results in broached mounting and locating surfaces for the axle drive gears and the transfer gears.
• critical toler ⁇ ances between the surfaces can be easily maintained resulting in a precisionally manufactured differential case at a substantially reduced cost as compared to assembled differential cases or cases requiring a multitude of machining steps.
• the present invention is adaptable to a variety of differential assemblies.
• the invention has been disclosed in connection with a differential that includes a single pair of transfer gears 172 located in each window 140.
• the present invention also can be used to produce a differential case for use with a differential that includes additional gearing within the windows such as the differential assembly disclosed in co-pending application, Serial No. 475,526, filed concurrently herewith in the name of Vernon E. Gleasman ' and entitled "Differential Gearing Assembly" .

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Retarders (AREA)
• General Details Of Gearings (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23887967

Family Applications (1)

Country Status (9)

Cited By (1)

Citations (21)

Family Cites Families (1)

• 1984
  • 1984-02-27 EP EP84901170A patent/EP0138888B1/en not_active Expired
  • 1984-02-27 WO PCT/US1984/000283 patent/WO1984003743A1/en active IP Right Grant
  • 1984-02-27 AU AU26556/84A patent/AU2655684A/en not_active Abandoned
  • 1984-02-27 JP JP1984600010U patent/JPH0135962Y2/ja not_active Expired
  • 1984-02-27 DE DE8484901170T patent/DE3470922D1/de not_active Expired
  • 1984-03-14 KR KR1019840001299A patent/KR930001573B1/ko not_active Expired - Fee Related
  • 1984-03-14 MX MX200661A patent/MX158994A/es unknown
  • 1984-03-15 IT IT20064/84A patent/IT1173848B/it active
  • 1984-03-15 BE BE212571A patent/BE899166A/fr unknown

Patent Citations (21)

Non-Patent Citations (1)

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