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EP-3507527-B1 - OFFSET IDLER HUB FOR BACKLASH CONTROL

EP3507527B1EP 3507527 B1EP3507527 B1EP 3507527B1EP-3507527-B1

Inventors

  • MOENSSEN, DAVID J.
  • ABRAM, KWIN

Dates

Publication Date
20260506
Application Date
20170816

Claims (5)

  1. An apparatus (100), comprising: a crankshaft gear (106) operatively coupled to an engine (102), the crankshaft gear (106) having a crankshaft gear centerline (122); an auxiliary gear (108) operatively coupled to the engine (102), the auxiliary gear (108) having an auxiliary gear centerline (124); an idler gear (104) operatively coupled to the engine (102), the idler gear (104) in meshed engagement with each of the crankshaft gear (106) and the auxiliary gear (108), the idler gear (104) having an idler gear centerline (116); a ring dowel (115) fixedly coupled to an engine block (114) of the engine (102), the ring dowel having a ring dowel centerline (120), the ring dowel centerline (120) offset from the idler gear centerline (116); and an idler hub (110) having an inner surface (148) and an outer surface (150), characterized in that the inner surface (148) is fixedly coupled to the ring dowel and the idler gear (104) is rotatably coupled to the outer surface (150), the idler hub (110) being eccentrically-shaped.
  2. The apparatus (100) of claim 1, wherein: a first distance between the ring dowel centerline (120) and the crankshaft gear centerline (122) defines a nominal crankshaft gear center distance, and a second distance between the ring dowel centerline (120) and the auxiliary gear centerline (124) defines a nominal auxiliary gear center distance; a third distance between the idler gear centerline (116) and the crankshaft gear centerline (122) defines an offset crankshaft gear center distance, and a fourth distance between the idler gear centerline (116) and the auxiliary gear centerline (124) defines an offset auxiliary gear center distance; and a difference between the nominal crankshaft gear center distance and the offset crankshaft gear center distance is greater than 1.500 mm.
  3. The apparatus (100) of claim 2, wherein a difference between the nominal auxiliary gear center distance and the offset auxiliary gear center distance is less than 0.500 mm.
  4. The apparatus (100) of claim 2 or claim 3, wherein: a connecting line is defined between the ring dowel centerline (120) and the auxiliary gear centerline (124), the connecting line defining a first angle relative to a datum on the engine block (114); and the idler gear centerline (116) is offset from the ring dowel centerline (120) by a first magnitude and a second angle relative to the datum; wherein optionally the second angle is offset from the first angle by 90 degrees.
  5. The apparatus (100) of any preceding claim, wherein: the inner surface (148) of the idler hub (110) defines a first central axis (154); the outer surface (150) of the idler hub (110) defines a second central axis (156); and the second central axis (156) is offset from the first central axis (154); wherein optionally the second central axis (156) is offset from the first central axis (154) a distance of 0.250 mm.

Description

TECHNICAL FIELD The present invention relates generally to the field of gear systems. In particular, the present invention relates to apparatuses comprising a crankshaft gear, an auxiliary gear, an idler gear, a ring dowel, and an eccentrically-shaped idler hub, as set out in the appended claims. BACKGROUND A gear train is a system including two or more meshed gears. Some gear trains include an idler gear, which is an intermediate gear that transfers torque between gears, but does not itself drive a shaft to perform work. Idler gears are sometimes used to reverse the direction of rotation between gears. Backlash in a gear train refers to an amount of clearance between mated gear teeth. Whenever the direction of movement is reversed, gear teeth move from contact on one side to the other as the backlash gap is traversed. The corresponding impact of the teeth causes undesirable noise and vibration. Manufacturing tolerances preclude zero backlash, because all teeth cannot be manufactured to the exact same dimension, and all teeth must mesh without jamming. EP1113195, JP2003148608, US2013175963, and JP2003156144 describe various control units for transmissions. KR20160026187 describes a clearance control type-gear assembly having a backlash restriction function which sets a clearance between a drive gear and an idle gear and between a driven gear and an idle gear. SUMMARY The present invention is as described in the appended claims. The features of the claimed invention, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the several drawings described below. BRIEF DESCRIPTION OF DRAWINGS The details of one or more implementations are set forth in the accompanying drawings and the description below. Fig. 1 is a perspective view of a gear train for an engine, according to an embodiment.Fig. 2 is a front elevational view illustrating an engine block of the engine of Fig. 1 without the gear train.Fig. 3 is a front elevational view illustrating the offset idler hub of Fig. 1.Fig. 4 is a flow diagram illustrating a method of manufacturing an engine, not forming part of the present invention. DETAILED DESCRIPTION The invention relates to an offset idler hub for use in a gear train including an idler gear, a crankshaft gear, and an auxiliary gear. The offset idler hub is structured to offset a position of the idler gear relative to the crankshaft gear so as to reduce backlash between the crankshaft gear and the idler gear, while maintaining a nominal backlash between the auxiliary gear and the idler gear compared to a system having a symmetric (non-offset) idler hub. Also described ,but not forming part of the invention, is a method of manufacturing an engine, including evaluating backlash and selecting one of an offset idler hub and a symmetric idler hub so as to minimize backlash between the crankshaft gear and the idler gear. Fig. 1 is a perspective view of a gear train 100 for an engine 102, according to an embodiment. The gear train 100 includes an idler gear 104 in meshed engagement with each of a crankshaft gear 106 and an auxiliary gear 108. In an embodiment, the auxiliary gear 108 is a fuel pump pinion. The idler gear 104 is structured to transfer torque between the crankshaft gear 106 and the auxiliary gear 108. The idler gear 104 is rotatably coupled to an offset idler hub 110. More specifically, the idler gear 104 includes a bushing 112 that contacts the offset idler hub 110 to facilitate rotation of the idler gear 104 relative to the offset idler hub 110. The offset idler hub 110 is fixedly coupled (e.g., press-fit) to an engine block 114 of the engine 102. A ring dowel 115 is fixedly coupled (e.g., press-fit) to the engine block 114, and the offset idler hub 110 is fixedly coupled (e.g., press-fit) to the ring dowel 115. The idler gear 104 defines an idler gear centerline 116, the offset idler hub 110 defines an idler hub centerline 118, and the ring dowel 115 defines a ring dowel centerline 120. The idler gear centerline 116 and the idler hub centerline 118 are shown by a single line because they are coaxial. Additionally, the crankshaft gear 106 defines a crankshaft gear centerline 122 and the auxiliary gear 108 defines an auxiliary gear centerline 124. In conventional systems including a symmetric idler hub, each of the idler gear centerline 116, the idler hub centerline 118, and the ring dowel centerline 120 would be concentric. Tthe offset idler hub 110 is eccentrically-shaped so as to offset the idler gear centerline 116 from the ring dowel centerline 120. The eccentric shape of the offset idler hub 110 is defined so as to offset the idler gear centerline 116 (and idler hub centerline 118) from the ring dowel centerline 120 by a particular angle and magnitude relative to the engine block 114. The particular angle and ma