DIFFERENTIAL MOUNTING SYSTEM

Abstract

Vehicle powertrain, including: a power machine (22) having an outer surface with an outwardly directed locking feature (100) projecting from it and defining outer mating surfaces (128); and a differential (56) coupled to a transfer case by a drive shaft (58) and comprising a housing (68) with an inwardly directed locking feature (82) defining inner mating surfaces (92), wherein the outwardly directed locking feature (100) is arranged in the inwardly directed locking feature (82) such that the outwardly and inwardly directed mating surfaces (128, 92) engage and connect the differential (56) to the power unit (22), wherein the inwardly directed locking feature (82) further comprises first and second arms (86, 88) connected to each other by a rear wall to define a cavity (90) that receives the outwardly directed locking feature (100), and wherein the inner mating surfaces (92) are located on the arms (86, 88).wherein the outwardly directed locking feature (100) defines a threaded hole (76) and the inwardly directed locking feature (82) defines a borehole and a fastening element (73) is arranged in the threaded hole (76) and the borehole.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a motor vehicle having a differential mounted on an engine. BACKGROUND

[0002] Vehicles have a drivetrain for providing torque to one or more driven wheels of the vehicle. The drivetrain can be operated to selectively send torque to the front wheels, the rear wheels, or both, depending on operating conditions. JP H04-252 733 A already discloses a vehicle drivetrain with an engine and a differential coupled to a transfer case. JP H06-270 704 A discloses a differential, and WO 2007 / 031 687 A1 relates to a device for attaching a motor vehicle element to the vehicle engine. SUMMARY

[0003] According to the invention, a vehicle drive train having the features of claim 1 is proposed. Advantageous embodiments are specified in the dependent claim and the following description. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic representation of an exemplary vehicle. Fig. 2 is a perspective view of an exemplary vehicle powertrain. Fig. 3 is a side view of an engine of the vehicle powertrain shown in Fig. 2 is shown. Fig. 4 is a perspective view of a side wall of an engine of the vehicle powertrain shown in Fig. 2 is shown. Fig. 5 is a side view of a front differential of the drive train shown in Fig. 2 is shown. Fig. 6 is a side view of a connection between an engine and a front differential. Fig. Figure 7 is a side view of another front differential. Fig. 8 is a side view in cross section of another connection between an engine and a front differential. DETAILED DESCRIPTION

[0004] Embodiments of the present disclosure are described herein. It should be understood, however, that the disclosed embodiments are merely examples, and that other embodiments may take various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art how to variously employ the present invention.It will be apparent to one of ordinary skill in the art that various features illustrated and described with reference to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be required for particular applications or implementations.

[0005] With reference to Fig. 1, a vehicle 20 (such as a four-wheel drive vehicle or a four-wheel drive vehicle) may include an engine 22 having at least a cylinder block and a cylinder head attached to a top of the block. A crankshaft and pistons are disposed within the cylinder block. A flywheel of the engine 22 is connected to the crankshaft and disposed on a rear side of the engine 22. The engine 22 may be longitudinally mounted (i.e., the crankshaft extends in the longitudinal direction of the vehicle) or may be transversely mounted (i.e., the crankshaft extends in the transverse direction of the vehicle). A transmission 24 is attached to the rear of the engine 22 and has an input shaft operatively coupled to the flywheel.

[0006] A transfer case 26 is attached to the rear of the transmission 24 and operatively coupled to an output shaft of the transmission 24. The transfer case 26 is configured to provide torque to the front wheels 46 and / or the rear wheels 34, depending on the operating conditions of the vehicle 20. The transfer case 26 sends torque to the rear wheels 34 through a rear driveshaft 28. The driveshaft 28 may extend from the transfer case 26 to the rear differential 30. The rear differential 30 is operatively coupled to the rear wheels 34 through one or more rear axle half-shafts 32. The transfer case 26 sends torque to the front wheels 46 through a front driveshaft 36. The driveshaft 36 may extend from the transfer case 26 to the front differential 38. The front differential 38 is operatively coupled to the front wheels 46 by one or more front axle half-shafts.For example, the front axle may include a passenger-side half-shaft 40 connected between the front differential 38 and the passenger-side front wheel, and a driver-side half-shaft 42 connected between the front differential 38 and the driver-side front wheel. In the illustrated embodiment, the front differential 38 is connected to a passenger-side outer wall 39 of the engine 22, and the driver-side half-shaft 42 extends through an axle tunnel defined in the engine 22. A support housing 44 may be disposed on one side of the engine to support the driver-side half-shaft 42. Alternatively, the front differential 38 may be attached to a driver-side side of the engine 22, with the passenger-side half-shaft extending through the engine 22.

[0007] The front differential can be mounted on several different engine surfaces, depending on the driveline design and engine construction. Internal combustion engines come in many variations: traditionally, engine assemblies had a single-piece block containing cylinders, a crankcase, and oil pan mounting surfaces; however, more recently, modular systems (such as ladder-frame engines) have been used. In a ladder-frame engine, the cylinder block assembly is divided into a variety of components, including the cylinder block and a structural frame.

[0008] With reference to Fig. 2, an exemplary powertrain 50 includes an engine 52, a transmission 54, a front differential 56, a transfer case (not shown), and a front driveshaft 58 that cooperate as described above. In one embodiment, the engine 52 is a ladder-frame engine that includes a cylinder block 60, a structural frame 62, and an oil pan 64. The structural frame 62 defines an outer sidewall 66 to which the front differential 56 may be mounted.

[0009] The front differential 56 may include a housing 68 attached to the engine 52 and a cover 70. The front differential 56 also includes a transmission operatively coupled to the front driveshaft 58. The housing 68 defines a plurality of mounting holes 72 aligned with a plurality of bosses 74 defined on the sidewall 66. A plurality of mechanical fasteners 73 (e.g., bolts) are received through the mounting holes 72 and threaded into the threaded holes 76 defined in the bosses 74. In some embodiments, the oil pan 64 may also define bosses that receive fasteners for attaching the differential 56 to the oil pan 64 in addition to the engine. Here, the oil pan may be a cast component that can provide structural support, unlike conventional, thin-walled stamped steel oil pans that are not structural members.

[0010] The fasteners 73 collectively have a clamp load acting through the front differential against the torque load to prevent the front differential 56 from moving relative to the engine. If the torque load through the front differential 56 exceeds the clamp load, the differential will twist relative to the engine 52, which is an unacceptable condition. The clamp load can be increased by increasing the size or number of fasteners. However, powertrain space constraints may limit the size and number of fasteners used to connect the front differential 56 to the engine 52. Unless exotic fastener materials are used, the size and number of fasteners will determine the clamp load limit.Additional locking features between the engine 52 and the differential 56 may be used in conjunction with the fasteners 73 to increase the robustness of the engine-to-differential connection while maintaining or reducing the size of the engine-to-differential connection.

[0011] Fig. 3 and Fig. 4 illustrate enlarged views of the sidewall 66 of the engine 52. The sidewall 66 defines a plurality of bosses 74 having threaded holes 76. The sidewall also defines an axle tunnel 80 that extends completely through the frame 62 below the crankshaft and above the oil pan. The driver-side half shaft may extend through the axle tunnel 80. The axle tunnel 80 may define a seat 83 that engages a portion of the front differential 56 when installed.

[0012] A plurality of first locking features 82, which in the illustrated embodiment are inward-facing locking features, are disposed on the sidewall 66. Each of the locking features 82 may include a base 84 disposed against the sidewall 66, a first arm 86 extending outwardly from the base 84, and a second arm 88 also extending outwardly from the base 84, generally forming a C-shaped component. The first and second arms 86, 88 are spaced apart to define an open cavity 90 that receives a corresponding locking feature of the differential. A surface of the base 84 forms a rear wall of the cavity 90. In some embodiments, the first locking features 82 are integrally formed with the engine.

[0013] Fig. 5 illustrates the differential housing 68 with second locking features 100 disposed on the inner side 102 of the housing. The inner side 102 faces the cover 70 and toward the engine 52 when the differential is installed. In the illustrated embodiment, the second locking features 100 are outwardly directed features (or protrusions) that extend outwardly from the inner side 102 and are received within the cavity 90 of the first locking features 82. Each of the outwardly directed locking features 100 includes a base 104 connected to the inner sidewall 102, a distal end 106, and sidewalls 108 extending between the base 104 and the distal end 106. In the illustrated embodiment, the protrusion 100 has a prismatic cube-like shape with a top and four sidewalls; however, this disclosure is not limited to this particular shape.In some embodiments, the second locking features 100 are integrally formed with the differential housing 68. The inner surface 102 also includes a front axle bore 110 that receives one of the front half shafts.

[0014] With reference to Fig. 6 illustrates a side view of the connection 114 between the first and second locking features 82, 100. The cavity 90 of the inward locking feature 82 receives the distal end 106 and a portion of the sidewalls 108 therein. The first and second arms 86, 88 each define an internal engagement (or mating) surface 92 that engages external engagement (or mating) surfaces 93 of the sidewalls 108. The first arm and second arm also include steps 94 that are raised relative to the engagement surfaces 92 and engage the distal end 106 to prevent the outward locking feature 100 from penetrating further into the cavity 90. The outward locking feature 100 may have a beveled edge 112 at the distal end 106 so that the outward locking feature 100 may be more easily received within the cavity 90.The locking features are sized to create a friction fit between the engagement surfaces 92 and corresponding sidewalls 108. The compression between the locking features can be adjusted, depending on the embodiment, to create a tighter or looser interference fit. Since the differential is also attached to the engine with fasteners, a loose interference fit may be sufficient to ensure the differential is stationary relative to the engine. In one embodiment, the distance between the arms corresponds to the diameter of the boss 100.

[0015] A majority of the reaction forces for each link 114 occur in a direction perpendicular to the engagement surfaces 92. Accordingly, a variety of locking features with different orientations can be used to ensure that the differential is supported in both the up-and-down and left-and-right directions. In the illustrated example from Fig. 4 and Fig. 5, three links 114 are used. Two of the three links have horizontal engagement surfaces corresponding to up-and-down movement, and one of the links has engagement surfaces that are vertical and resist left-and-right movement. One of the links, link 115, has an upper engagement surface 116 that is vertically aligned with the longitudinal centerline of the axle tube 80 (which is also the centerline of the front axle). This places the surface 116 normal to the torque load of the differential, which is the most efficient orientation for resisting the torque load.

[0016] The illustrated embodiments are merely examples, and other connection configurations are contemplated by the present disclosure. It will be understood that the outward and inward locking features may be present on either the engine or the differential. For example, the engine may have the outward locking features, and the differential may have the inward locking features.

[0017] The outward locking feature may be installed into the inward locking feature by a machine that locks the differential, or the fasteners 73 may be tightened to anchor the outward locking feature into the inward locking feature.

[0018] Fig. Figure 7 illustrates another front differential having a housing 120 defining an inner side 122. The housing 120 defines an axle hole 124 that receives the front axle half-shaft. An array of locking features is radially disposed about the center of the axle hole 124. The array includes two outwardly directed locking features 126 and one inwardly directed locking feature 130. It will be understood that in other embodiments, the array may include more or fewer of each of the various locking features. Each of the outwardly directed locking features 126 may protrude from the inner side 122 and includes sidewalls extending from a distal end of the locking feature to the outer side 122.Two or more of the sidewalls have outward engagement surfaces 128 that engage corresponding surfaces of the corresponding inward locking feature disposed on the engine. At least one of the engagement surfaces 128 may be arranged such that the engagement surfaces 128 provide a reaction force (R) perpendicular to a direction of the torque load (τ) of the front differential.

[0019] The assembly also includes at least one inward locking feature 130 having a pair of arms 132 projecting outward from the inner side 122. The arms 132 are spaced apart to define a cavity 134 for receiving a corresponding outward locking feature disposed on the engine. Each of the arms defines an inward engagement surface that engages a corresponding engagement surface on the outward locking feature. At least some of the engagement surfaces 136 may be arranged such that the engagement surfaces 136 provide a reaction force perpendicular to a direction of the front differential torque load.

[0020] With reference to Fig.8, another front differential 150 includes a housing having a flange portion 152 with an outward locking feature 154 extending outward therefrom. The outward locking feature 154 engages the inward locking feature 156 disposed on the engine 158 to create a connection 166 that at least partially secures the differential to the engine. In this embodiment, at least one of the connections includes not only the outward and inward locking features, but also a fastener 164 extending through the locking features. The front differential 150 defines a bore 162 that extends completely through the outward locking feature 154.The engine 158 defines a threaded hole 160 having an opening located in the base of the inward locking feature 156. A fastener 164 extends through the bore 162 and is threaded into the threaded hole 160. Centering the fastener 164 in the locking features allows for easier mounting of the differential to the engine.

[0021] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The terms used in the description are for the purpose of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. As described above, the features of the various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. Although various embodiments may have been described as providing advantages over other embodiments or prior art implementations with respect to one or more desired characteristics,are preferable to these, those of ordinary skill in the art will understand that compromises may be made with respect to one or more features or characteristics to achieve desired overall system characteristics depending on the specific application and implementation. These characteristics may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Thus, embodiments described as less desirable than other prior art embodiments or implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for certain applications.

Claims

[1] Vehicle powertrain, comprising: a prime mover (22) having an outer surface with an outwardly directed locking feature (100) projecting therefrom and defining outer mating surfaces (128); and a differential (56) coupled to a transfer case by a drive shaft (58) and having a housing (68) with an inward locking feature (82) defining inner mating surfaces (92), the outward locking feature (100) being disposed within the inward locking feature (82) such that the outward and inward mating surfaces (128, 92) engage and connect the differential (56) to the engine (22), the inward locking feature (82) further including first and second arms (86, 88) interconnected by a back wall to define a cavity (90) receiving the outward locking feature (100), and the inner mating surfaces (92) being located on the arms (86, 88),wherein the outwardly directed locking feature (100) defines a threaded hole (76) and the inwardly directed locking feature (82) defines a borehole and a fastener (73) is disposed in the threaded hole (76) and the borehole., [2] The vehicle powertrain of claim 1, wherein the inward locking feature (82) includes a base (84) disposed on the housing (68) and the inner mating surfaces (92) extend outwardly from the base (84).

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