Suspension device and assembly method therefor

Patent metadata

Field	Value
Publication number	US-11472250-B2
Application number	US-202117636515-A
Country	US
Kind code	B2
Filing date	Jan 25, 2021
Priority date	Feb 5, 2020
Publication date	Oct 18, 2022
Grant date	Oct 18, 2022

Abstract

A suspension device has an upper shell having a stepped section around an inner circumferential surface; a lower shell; a ball screw shaft rotatably supported by the upper shell; a bearing unit arranged between a part of the ball screw shaft and the upper shell, and having an outer side part in a radial direction including a side surface that comes in contact with a side surface on the other side in the axial direction of the stepped section; a ball nut screwed on the ball screw shaft; an inner tube joined to the lower shell and the ball nut; an electric motor; and a coil spring, and a circumscribed circle diameter of the ball nut and the inner tube is less than an inner diameter dimension of the stepped section.

First claim

The invention claimed is:

1. A suspension device comprising:
an upper shell having a tubular shape and having a stepped section around an inner circumferential surface of an intermediate section in an axial direction;
a lower shell arranged around a part on one side in the axial direction of the upper shell, and able to displace in the axial direction relative to the upper shell, but not able to rotate;
a ball screw shaft having a male ball screw groove around an outer circumferential surface of a part on the one side in the axial direction, and rotatably supported on an inner side of the upper shell;
a bearing unit arranged between a part on the other side in the axial direction of the ball screw shaft and the upper shell, and having an outer side part in a radial direction that is prevented from rotating with respect to the upper shell and that includes a side surface on the one side in the axial direction that comes in direct contact with or comes in contact through another member with a side surface on the other side in the axial direction of the stepped section, the bearing unit rotatably supporting the ball screw shaft with respect to the upper shell;
a ball nut having a female ball screw groove around an inner circumferential surface, the ball nut being screwed on the ball screw shaft;
a plurality of balls arranged between the male ball screw groove and the female ball screw groove so as to be able to freely roll;
an inner tube joined to the lower shell and the ball nut;
an electric motor having an output shaft that is connected to an end section on the other side in the axial direction of the ball screw shaft so as to be able to transmit torque, and supported by an end section on the other side in the axial direction of the upper shell; and
a coil spring held in an elastically compressed state in the axial direction between the upper shell and the lower shell;
wherein
the bearing unit includes a bearing holder, a pressing plate, and a rolling bearing,
the bearing holder includes a holder cylinder section, an outward-facing flange section that is bent toward an outer side in the radial direction from an outer circumferential surface of an end section on the one side in the axial direction of the holder cylinder section, the outward-facing flange section being fastened and internally fitted with the upper shell so as to prevent the bearing holder from rotating with respect to the upper shell, and an inward-facing flange section that is bent toward an inner side in the radial direction from an inner circumferential surface of an end section on the other side in the axial direction of the holder cylinder section,
the pressing plate includes an annular section having the side surface on the one side in the axial direction that comes in direct contact with or comes in contact through another member with the side surface on the other side in the axial direction of the stepped section, and a plate cylinder section that is bent toward the other side in the axial direction from an end section on the inner side in the radial direction of the annular section, the plate cylinder section being internally fitted with the end section on the one side in the axial direction of the holder cylinder section without looseness,
the rolling bearing includes an inner ring that is externally fitted by press fitting with a part on the one side in the axial direction of the ball screw shaft, and an outer ring that is internally fitted with the holder cylinder section of the bearing holder and is held in the axial direction between a side surface on the one side in the axial direction of the inward-facing flange section and an end surface on the other side in the axial direction of the plate cylinder section, and
a circumscribed circle diameter of the ball nut and the inner tube is less than an inner diameter dimension of the stepped section.

2. The suspension device according to claim 1 , wherein
the upper shell has a flange section that protrudes toward an inner side in the radial direction in the intermediate section in the axial direction, and the stepped section is configured by the flange section.

3. The suspension device according to claim 1 , comprising
a bump stopper having an outer diameter dimension that is equal to or less than the inner diameter dimension of the stepped section and is arranged around a part on the other side in the axial direction of the ball screw shaft, and having an outer circumferential surface that comes in contact with or closely faces an inner circumferential surface of the stepped section.

4. The suspension device according to claim 3 , wherein
a stopper holder that is internally fitted with a part on the other side in the axial direction of the bump stopper, and
the stopper holder has an annular section that is held between the stepped section and the side surface on the one side in the axial direction of the bearing unit, and a cylindrical section that is bent toward the one side in the axial direction from an end section on the inner side in the radial direction of the annular section and is internally fitted with a part on the other side in the axial direction of the bump stopper.

5. An assembly method for the suspension device according to claim 1 comprising
a process of positioning the ball screw shaft in the axial direction with respect to the upper shell by arranging the balls and the ball nut around a part on the one side in the axial direction of the ball screw shaft, and together with joining and fastening the inner tube to the ball nut, externally fitting and fastening the bearing unit around a part on the other side in the axial direction of the ball screw shaft to form an intermediate assembly, then inserting the intermediate assembly into the inner side of the upper shell from an opening on the other side in the axial direction of the upper shell starting with the end section on the one side in the axial direction of the intermediate assembly, passing the ball nut and the inner tube through the inner side in the radial direction of the stepped section, and bringing the side surface on the one side in the axial direction of the part on the outer side in the radial direction of the bearing unit that is externally fitted with and fastened to the ball screw shaft in direct contact with or in contact through another member with the side surface on the other side in the axial direction of the stepped section.

Assignees

• Nsk Ltd

Inventors

• Yamamoto Shin
• Sushi Takahiro
• KYO Cyou
• Oike Mitsuru
• Suzuki Shunsuke

Classifications

• F16F15/03

  using {magnetic or} electromagnetic means (F16F9/53, {F16F15/005} take precedence) · CPC title

• B60G2202/312

  The spring being a wound spring · CPC title

• B60G2204/45021

  for limiting upper mount movement of a McPherson strut · CPC title

• B60G15/04 Primary

  and mechanical damper {or dynamic damper} · CPC title

• B60G17/021

  the mechanical spring being a coil spring (B60G17/0272 takes precedence) · CPC title