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Toroidal type continuously variable transmission

  • US 6,991,579 B2
  • Filed: 10/17/2002
  • Issued: 01/31/2006
  • Est. Priority Date: 10/19/2001
  • Status: Active Grant
First Claim
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1. A toroidal type continuously variable transmission comprising:

  • a rotating shaft;

    a pair of first discs each having an inner side surface and supported around said rotating shaft displaceably in an axial direction of said rotating shaft and rotatably in sync with said rotating shaft;

    a second disc having an inner side surface opposed to said inner side surface of one of said first discs and disposed concentrically with said first disc and rotatably independently of said first discs;

    a plurality of trunnions provided between said first and second discs so as to swing around pivot shafts located in twisted positions with respect to central axes of said two discs, respectively;

    displacement shafts projecting from inner side surfaces of said trunnions;

    power rollers sandwiched between said inner side surfaces of said first and second discs so as to be supported on said displacement shafts rotatably, respectively;

    a hydraulic pressing unit provided between said rotating shaft and said one of said first discs and for pressing said one of said first discs toward said second disc in accordance with pressure oil fed to said pressing unit;

    a preload spring provided between said rotating shaft and said one of said first discs and for pressing said one of said first discs toward said second disc even when said pressing unit is not operated; and

    a ball spline for supporting said one of said first discs displaceably in said axial direction of said rotating shaft and rotatably in sync with said rotating shaft,wherein said ball spline includes a first spline groove formed in an outer circumferential surface of said rotating shaft, a second spline groove formed in an inner circumferential surface of said one of said first discs, and balls provided between said first spline groove and said second spline groove rollably; and

    wherein an axial position of an end portion of an effective groove portion of said first spline groove is located so as to correspond to an axial position of an inner end portion of said second spline groove or is located more closely to said second disc than is said axial position of said inner end portion, wherein the locations of said effective groove portion and said inner end portion are determined when said pressing unit, said preload spring and said one of said first discs are installed around said rotating shaft, pressure oil is not fed to said pressing unit, and said preload spring is not elastically deformed.

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