Steering spline telescoping shaft, and steering device
A spline telescoping shaft includes an inner shaft including a male spline and a tubular outer shaft including a female spline. A resin film is provided on a surface of at least either of both the splines. An addendum modification coefficient e, the number of teeth Z, a module m, a reference pitch circle diameter PCD, a tip circle diameter d 1 and a root circle diameter d 2 of the male spline and a tip circle diameter D 1 and a root circle diameter D 2 of the female spline have relations expressed by expressions (1) to (8). m ( Z +4)> d1>m ( Z +2) (1), mZ>d2>m ( Z −1) (2), m ( Z +4)> D2>m ( Z +2) (3), mZ>D1>m ( Z −1) (4), D2>d1 (5), D1>d2 (6), PCD=mZ (7), and 0.4< e <1.1 (8)
1. A steering spline telescoping shaft that transmits steering torque, comprising:
an inner shaft and a tubular outer shaft that are spline fitted together so as to slide in an axial direction,
wherein the outer shaft includes a female spline,
wherein the inner shaft includes a male spline that fits in the female spline,
wherein a resin film is provided on a surface of at least either of the female spline and the male spline,
wherein the female spline and the male spline each have a profile that is modified in a tooth depth direction with an addendum modification coefficient “e”, and
wherein following expressions (1) to (8) are met:
m ( Z+ 4)> d 1 >m ( Z+ 2) (1)
mZ>d 2 >m ( Z− 1) (2)
m ( Z +4)> D 2 >m ( Z+ 2) (3)
mZ>D 1 >m ( Z −1) (4)
D2>d1 (5)
D1>d2 (6)
PCD=mZ (7)
0.4<e<1.1 (8)
wherein, in the expressions (1) to (8), Z is a number of teeth of each spline, m is a module, PCD is a reference pitch circle diameter, d 1 is a tip circle diameter of the male spline, d 2 is a root circle diameter of the male spline, D 1 is a tip circle diameter of the female spline, and D 2 is a root circle diameter of the female spline.
2. A steering device comprising:
a steering member;
a steering mechanism configured to operate in association with the operation of the steering member to turn wheels; and
a steering shaft configured to transmit a steering force of the steering member to the steering mechanism,
wherein a part of the steering shaft includes the steering spline telescoping shaft according to claim 1 .