# US 2019/0316627 A1 · Torsion bar assembly and method of assembling same

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- Number: US 2019/0316627 A1
- Document ID: US20190316627A1
- Status: Published application
- Kind: A1
- Application number: 16/382,779
- Filed: 2019-04-12
- Published: 2019-10-17
- Earliest claimed: 2018-04-13
- Assignees: TRW Inc.
- Applicants: TRW Limited
- Inventors: Stephen Butler; Jose Martins; James Stephen Ironside
- Web page: https://patentgrep.com/patent/US20190316627A1

## CPC

- F16C 1/08: End connections
- F16D 1/101: {without axial retaining means rotating with the coupling}
- F16D 1/112: the interengaging parts comprising torque-transmitting surfaces, e.g. bayonet joints
- F16D 3/10: Couplings with means for varying the angular relationship of two coaxial shafts during motion
- F16D 2001/102: {the torque is transmitted via polygon shaped connections}
- F16D 2001/103: {the torque is transmitted via splined connections}
- Y10T 403/1616: Position or guide means
- F16C: SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A torsion bar assembly comprises an input shaft, an output shaft, and a torsion bar that connects the input shaft to the output shaft. An end stop face on the input shaft that co-operates with a respective end stop face of the output shaft to limit an angular deflection of the torsion bar assembly in a first direction away from the neutral position and an end stop face on the input shaft that co-operates with a respective end stop face of the output shaft to limit an angular deflection of the torsion bar assembly in a second direction that opposes the first direction. A first alignment feature is provided at or close to the end of the input shaft nearest the output shaft and a second alignment feature is provided at or close to an end of the output shaft nearest to the input shaft, the first alignment feature facing the second alignment feature across a gap. The alignment features each define respective contact surfaces such that if the input shaft and the output shaft are pressed axially towards each other to close up the gap the contact faces co-operate to set relative angular positions of the input shaft and the output shaft to correspond to a neutral position.

## Claims

### Claim 1

A torsion bar assembly comprising:
an input shaft;
an output shaft;
a torsion bar that connects the input shaft to the output shaft and fixes a relative angular position of the input shaft and output shaft at a neutral position when no torque is carried by the torsion bar;
at least one end stop face on the input shaft that co-operates with a respective end stop face of the output shaft to limit an angular deflection of the torsion bar assembly in a first direction away from the neutral position;
at least one end stop face on the input shaft that co-operates with a respective end stop face of the output shaft to limit an angular deflection of the torsion bar assembly in a second direction that opposes the first direction;
a first alignment feature provided at or close to an end of the input shaft nearest the output shaft and a second alignment feature provided at or close to an end of the output shaft nearest to the input shaft, the first alignment feature facing the second alignment feature across a gap so that the first and second alignment features do not contact each other over a range of angular movement of the torsion bar, the first and second alignment features each defining respective contact surfaces that are located such that if the input shaft and the output shaft are pressed axially towards each other to close up the gap the contact surfaces co-operate to set relative angular positions of the input shaft and the output shaft to correspond to the neutral position and to further prevent relative angular movement between the input shaft and the output shaft.

### Claim 2 (depends on 1)

The torsion bar assembly according to claim 1 in which the first alignment part or the second alignment part comprises a notch having side walls that define the contact surfaces and the other one of the first alignment part and the second alignment part comprises a protrusion such as a rib that has side walls that define the contact surfaces.

### Claim 3 (depends on 2)

The torsion bar assembly according to claim 2 in which the protrusion is a rib.

### Claim 4 (depends on 2)

The torsion bar assembly according to claim 2 in which the notch is provided on an outer circumferential face or an inner circumferential face of one of the input shaft and the output shaft, and the side walls of said extend from a tip of the said one shaft away from the tip and in which the protrusion is provided on an inner circumferential face of the other one of the input shaft and output shaft, extending from the tip of the other one of said shafts back along the other one of said shafts.

### Claim 5 (depends on 2)

The torsion bar assembly according to claim 2 in which the notch has opposed non-parallel side walls that form a V-shape, each side wall forming one contact surface of the first alignment part.

### Claim 6 (depends on 1)

The torsion bar assembly according to claim 1 in which the end stop faces comprise faces of dog teeth formed on the input shaft and dog teeth formed on the output shaft.

### Claim 7 (depends on 6)

The torsion bar assembly according to claim 6 in which the dog teeth on the input shaft and the dog teeth on the output shaft are defined as the side walls of a set of axially extending ribs spaced apart by notches.

### Claim 8 (depends on 7)

The torsion bar assembly according to claim 7 in which the first alignment feature is located along at least one of the notches defined between dog teeth of one of the input shaft and the output shaft, and the second alignment feature is located on the tip of at least one of the ribs defined by the dog teeth of the other one of the input shaft and the output shaft.

### Claim 9 (depends on 8)

The torsion bar assembly according to claim 8 in which a location of the first alignment feature is at the root of the notch, with the contact surfaces defined by inclined planar or non-planar wall portions that join the root to the side walls of the notch.

### Claim 10 (depends on 1)

The torsion bar assembly according to claim 1 in which an axial length of the first and second alignment features are less than the gap between the input shaft and output shaft to ensure the first and second alignment features are held clear during normal use of the torsion bar assembly.

### Claim 11

A method of assembly of a torsion bar assembly comprising the steps of:
supporting an input shaft and an output shaft a distance apart on a common axis such that one of the input and output shafts is prevented from rotating about that axis and other one of the input and output shafts is free to rotate;
pressing the input shaft towards the output shaft to bring alignment parts into engagement thereby self-centring the input and output shafts in a neutral position;
whilst the input shaft and output shaft are pressed together, pressing a torsion bar into the output shaft from an end furthest from the input shaft until splines on the torsion bar interfere with corresponding splines on the input shaft and on the output shaft; and
during a final stage of assembly, causing the input shaft to separate axially from the output shaft by a distance greater than an axial length of the alignment parts to permit free angular movement of the input shaft relative to the output shaft that is unimpeded by the alignment parts.