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-differen- tial mechanisms and in particular to a new and improved differential case for use with a cross axis compound planetary gear differential assembly.
• Patent No. 2,859,641 to Gleasman which is hereby incorporated by reference discloses a worm gear differen ⁇ tial mechanism, termed a "cross-axis compound planetary gear complex".
• the disclosed differential includes a differential case that mounts g-ear 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.
• three pairs of balancing gears are employed and hence the differential case assembly includes three windows. Al ⁇ though the differential, disclosed in this Gleasman patent, operates extremely well, it is nevertheless desirable to reduce its manufacturing cost.
• a new and improved differential is disclosed which includes an integral differential case that simplifies the construction and assembly of the differential 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 differen ⁇ tial 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 which is typically coincident with the central axis of the ring gear mounting flange.
• the intermediate por ⁇ tion of the differential case defines a through passage which in the illustrated and preferred embodiment, is four sided.
• the ends of the through passage form windows in which transfer gearing is mounted.
• Each gear window is defined, at least in part, by opposed, * spaced apart window wall sections, the sections being disposed in parallel planes that extend on either side of the axis of rotation of the differential case.
• these wall sections provide locating and reaction surfaces for the gears mounted within the window.
• the passage is further defined by another pair of spaced apart wall sections located along the passage intermediate the transfer gear windows.
• the wall sections are disposed in parallel planes that intersect and are substantially
• OMPI orthogonal to the axis of rotation of the differential case.
• These intermediate wall sections define locating and reaction surfaces for axle drive gears and/or thrust bearings disposed between inside of the the case and the axle drive gears.
• the construction of the differential case is dis ⁇ closed for use with a cross axis compound planetary gear differential of the type described in Gleasman Patent No. 2,859,641, but in which two pairs of balan ⁇ cing 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.
• the .intermediate portion defines pairs of aligned bores located at the transfer gear windows that extend per ⁇ pendicularly with respect to the window wall sections.
• the bores accept shafts which rotatably carry the transfer gears.
• the case preferably defines integ ⁇ rally formed lugs constructed to receive a retaining arrangement for securing the transfer gear shafts in position.
• the present invention also provides a new and im ⁇ proved method for making the differential case.
• a broaching process is used to machine at least two sides, but pre ⁇ ferably four sides, of the passage simultaneously.
• a four sided broaching tool is driven through the passage to finish machine the window wall sections and the intermediate or side gear wall sections. De ⁇ pending on the broach construction, both ends of the passage may be finished machined in a single broaching
• the differential case may be finished machined in a two step process in which a broaching tool is sequentially inserted from both ends of the passage to individually finish each transfer gear window.
• the disclosed differential case construction and method greatly reduces the expense associated with pro ⁇ ducing the differential described above.
• the casting from which the differential case is ultimately formed requires minimal machining to produce a finished product.
• high speed production of the differential can be achieved.
• each end portion of the differential case includes radial gusset-like ribs that radiate outwardly from the asso ⁇ ciated trunnion.
• the ribs provide added rigidity to the case and trunnion location without a substantial increase in overall weight.
• Figure 1 is a side elevational view of a differen ⁇ tial case constructed in accordance with the preferred embodiment of the invention
• Figure 2 is a left end view of the differential case shown in Figure 1;
• Figure 3 is a right end view of the differential case shown in Figure 1;
• Figure 4 is a sectional view of the " differential as seen from the plane indicated by the line 4-4 in Figure 1, shown with differential gear components.
• Figure 5 is another side elevational view of the differential case shown with a broaching tool in position;
• Figure 6 is a sectional view as seen- from the plane indicated by the line 6-6 in Figure 5;
• Figure 7 is a sectional view of an alternate differen ⁇ tial case embodying the present invention as seen from the plane indicated by the line 7-7 in Figure 8;
• Figure 8 is an end view of the alternate differential case
• Figure 9 is a side elevational view of the alternate differential case, rotated 90° from the position shown in Figure 7; and.
• Figure 10 is a sectional view of the case as seen from the plane indicated by the line 10-10 in Figure 9.
• FIG. 1 The overall construction of a differential case 10, constructed in accordance with the preferred embodi ⁇ ment of the invention is illustrated in Figures 1-3.
• the case 10 is formed from an integral casting and in ⁇ cludes end portions 10a, 10b disposed on either side of an intermediate portion 10c.
• the end portion 10a includes a trunnion 12 defining, at least in part, an internal bore 14 through which a drive axle (not shown) extends into engagement with internal gear components.
• the trunnion 12 is typically a machined annulus adapted to receive a bearing by which the differential case is rotatably mounted to a dif ⁇ ferential housing (not shown) .
• the trunnion extends outwardly from a larger diameter, unmachined hub 16 that defines a shoulder 16a against which the bearing (not shown) seats.
• the left end portion 10a (as viewed in Figure 1) also defines a flange 18 that includes a plurality of apertures 18a by which a ring gear (not shown) is mounted to the differential case.
• the flange 18 defines an axis of rotation 20 for the case 10.
• a plurality of re ⁇ inforcing, gusset-like ribs 22 radiate outwardly from the unmachined hub 16 and merge with the base of the mounting flange 18.
• the ribs 22 reinforce the end portion 10a and rigidize the location of the trunnion 12.
• the right end portion 10b is similarly configured and includes a trunnion 26 defining, at least partially, an axle receiving bore 28.
• the trunnion 26 is defined by a machined annulus that extends outwardly from an unmachined hub 30, of larger diameter, thereby defining a shoulder 30a against which a bearing (not shown) seats.
• radial ribs 32 radiate outwardly from the un ⁇ machined hub 30, to reinforce the right end portion 10b and the position of the trunnion 26.
• reliefs 36, 38 are formed in the hubs 16, 30, respectively, to provide clearance for a suitable bearing removal tool, in the event replacement of the differential bearings is required.
• the intermediate portion 10c is located between the end portions 10a, 10b.
• the intermediate portion defines a through passage 50, which in the preferred and illustrated embodiment is of a four sided configuration. Opposite ends of the passage (only one end is shown in Figure 1) define aligned open ⁇ ings 52, 54 or "windows" in which gear components, to be described, are operatively carried (shown in Figure 4).
• Each window 52, 54 is defined by opposed, machined window wall sections 56.
• the wall sections 56 are paral ⁇ lel and disposed in planes that extend on either side of the center line 20.
• the passage 50 is further defined by spaced apart wall sections 58 disposed intermediate the window wall sections 56, which provide mounting and reaction surfaces for axle drive differential gearing components to be described.
• the intermediate wall sections 58 define sur ⁇ faces disposed in parallel planes that extend orthogonally with respect to the axis of rotation 20.
• each transfer gear 60 includes an "irreversible” gear portion formed as a worm wheel 60a, for example, and a pair of “reversible” balancing gears such as spur gears 60b disposed at opposite ends of the worm wheel (only one spur gear of the pair is shown in Figure 4) .
• Axle drive gears 62 formed as "worm” gears are disposed centrally within the differential case and rotatably engage the ends of axles (not shown) which extend through the bores 14, 28.
• the axle drive gears 62 each include a splined internal bore 62a which is adapted to engage external splines formed on the axle end (not shown) .
• the worm wheel portions 60a of the transfer gears 60 engage the axle drive gears 62.
• the transfer gears 60 that form a pair, as seen in Figure 4, are coupled to each other by the spur gears 60b.
• the pairs of transfer gears 60 thus cross couple the axles to each other and split torque between the axles.
• the axle drive gears no. 62 and the irreversible gear portions 60a of the transfer gears 60 can be cross axes helical gears.
• the transfer gears 60 rotate on shafts 66.
• the shafts 66 span the windows 52, 54, their ends being supported by aligned bores 68 that open on one end into the windows.
• the other ends of the bores 68 open into relieved areas 70 formed on the periphery of the inter ⁇ mediate section 10c of the differential case at spaced locat i ons.
• a lug-like structure 72 separates - ⁇ tJ E ⁇ the adjacent relieved areas and includes a bore 74 (shown best in Figure 3) adapted to receive a pin 76 (shown in Figure 1) for maintaining the position of a shaft 66 in its associated bores 68. It should be noted that other arrangements can be used to maintain the shafts 66 in position.
• the gears are positioned between the wall sections 56 in alignment with the bores 68.
• the shafts 66 are passed from one bore 68 through the transfer gear 60 and into its associated, spaced bore 68. The position of the shaft is then fixed by the pin 76.
• axle drive gears 62 are disposed side-by-side within the differential case and are engaged by associated worm wheel portions 60a of -the transfer gears 60.
• Each of the axle drive gears 62 includes an outward end face 63 that abuts a respective one of the intermediate wall sections 58.
• the intermediate wall sections 58 locate the axle drive gears within the housing and can receive side loading or end thrust from the gears.
• a broaching process is used to machine the passage 50, and in particu ⁇ lar to simultaneously finish machine the window wall sections 56 and the intermediate wall sections 58.
• the differential is shown with a broaching tool 80 in position.
• the broach includes a plurality of vertical and trans ⁇ verse teeth 80a, 80b, respectively.
• the cross-section of the broach defines the finish dimension of the passage 50.
• the vertically oriented teeth (as viewed in Figure 5) cut the interme ⁇ diate wall sections 58 and the transversely oriented teeth 80b cut the window wall sections 56.
• the broach 80 is inserted from one end of the passage 50. As it passes through the passage 50, during a broaching cycle or cutting stroke, the window and intermediate wall sections 56, 58 are finish sized. In the preferred method, the broaching process provides the final surface finish for all of wall sections. As is conventional, the cross-section of the broach typically tapers from one end to the- other so that material is gradually cut from the passage 50.
• the passage 50 in the differential case can be finish machined in one step or multiple steps. For example, a roughing broach may initially be used to rough machine the passage followed by a finishing broach.
• the window wall sections 56 of both windows 52, 54 may be machined in one broaching cycle or, alternately, the broach 80 may be inserted from one end to finish one window opening 52 and then removed and reinserted from the other window to finish machine the window wall sec ⁇ tions 56 of the second window 54.
• the disclosed invention greatly reduces the manufac ⁇ turing cost of a differential case of the type that includes transfer gearing mounted in window openings that cross-couple axle drive gears.
• the integral cast ⁇ ing used for the differential case eliminates the cost incurred in assembling a differential case from indivi ⁇ dual components.
• machining the passage 50 with a broach or similar method precision locating and thrust surfaces for the transfer gears 60 and the axle drive gears 62 are obtained without undue expense.
• the "broached surfaces" in the passage eliminate the need for complex and expensive internal machining of the differential case that would otherwise be required.
• the differential case 10 illustrated in Figures 1-6 depicts my invention as originally conceived by me.
• MPI Figures 7-10 illustrate an alternate differential case, embodying my invention but which also includes improve ⁇ ments made by Gene A. Stritzel.
• the improvements are described and claimed in the co-pending application filed concurrently herewith in the name of Gene A. Stritzel, entitled “Improved Differential Apparatus and Method of Making” which has been incorporated by refer ⁇ ence.
• Figures 7 and 9 illustrate the overall construction of the alternate embodiment of a differential case 110.
• 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 7) includes a trunnion 112 formed by a machined annulus which is adapted to receive a bearing by which the trun ⁇ nion, and hence the differential case, is rotatably 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 differen ⁇ tial case.
• the right end portion 110b (as viewed in Figure 7) 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 differential case is rotatably mounted to a differential housing.
• the trunnions 114, 126 and ring gear flange 118 define an axis of rotation 120 for the differential case.
• unmachined portions of the trunnion hub, indicated by the reference character 130 include relief notches 132, spaced 180° apart, to.provide access for a bearing removing tool should replacement 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.
• the openings appear to define a through-passage 150 extending through the in ⁇ termediate 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 9 and 10) which are rotated 90° with respect to the windows 140.
• the intermediate portion 110c also includes re ⁇ Memos or relieved areas 158 between the windows 140 and the openings 156 so that, in section, and as seen in Figure 10, the intermediate section appears to comp ⁇ rise four L-shaped posts which, for purposes of explana ⁇ tion, shall be individually designated 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° 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
• the smaller diameter bores 168 receive shaft retainers 174, such as friction pins to maintain the transfer gear shafts 170 in position.
• annular, inwardly extending extensions 180, 182 of the end portions 110a, 110b are provided by 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 7, 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 exten ⁇ sion 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 trans ⁇ verse window wall sections 154 extend inwardly towards the center of the window 140.
• the finished surfaces are formed by a broaching process.
• a broaching tool such as shown in Figures 5 and 6
• 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 sur ⁇ faces, requiring a machine finish, are actually con ⁇ tacted by the broach.
• the amount of material removed during the broaching process is reduced and, in addition, the unmachined portions 154a of the transverse wall sections 154 (as viewed in Figure 7) as well as the additional clearance defined by the added spacing between the verti ⁇ cal wall sections 152, provide chip relief for the broach ⁇ ing process.
• 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 differential case results in broached mounting and locating surfaces for the axle drive gears and the transfer gears.
• all surfaces can be concurrently cut with a single tool, critical tolerances between the surfaces can be easily maintained resulting in a precisionally manufac ⁇ tured 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 60 located in each window 140.
• the present invention can also 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 appli ⁇ cation.
• Serial No. filed concurrently here ⁇ with 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)

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ID=23887954

Family Applications (1)

Country Status (8)

Cited By (1)

Citations (17)

Family Cites Families (1)

• 1984
  • 1984-02-27 JP JP1984600011U patent/JPH0135963Y2/ja not_active Expired
  • 1984-02-27 WO PCT/US1984/000284 patent/WO1984003744A1/en active IP Right Grant
  • 1984-02-27 DE DE8484901277T patent/DE3471141D1/de not_active Expired
  • 1984-02-27 AU AU26918/84A patent/AU2691884A/en not_active Abandoned
  • 1984-02-27 EP EP84901277A patent/EP0138910B1/en not_active Expired
  • 1984-03-14 KR KR1019840001300A patent/KR930001574B1/ko not_active Expired - Fee Related
  • 1984-03-15 IT IT20066/84A patent/IT1173850B/it active
  • 1984-03-15 BE BE212570A patent/BE899165A/fr unknown

Patent Citations (17)

Non-Patent Citations (1)

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