GB2301407A

GB2301407A - Differential torque control system converts differential rotation into an axial movement

Info

Publication number: GB2301407A
Application number: GB9511133A
Authority: GB
Inventors: Michael Bruce Gibson
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-05-31
Filing date: 1995-05-31
Publication date: 1996-12-04
Also published as: GB9511133D0

Abstract

The system comprises two coaxial members 1,6, which may be wheel shafts for example, interconnected such that relative rotational movement between the coaxial members 1,6 causes axial movement of a collar 3. One of the coaxial members 6 may terminate in an outer sleeve 4 containing the end of the other coaxial member 1 and the collar 3. The collar 3 may have a helical track 5 engaged by a component 7 fixed relative to the outer sleeve 4 to give the required axial movement. The outer sleeve 4 may be filled with a viscous medium having an externally controlled bypass. Springs or rubber pads could be used in addition or alternatively to the viscous medium.

Description

DIFFERENTIAL TORQUE CONTROL SYSTEM This invention refers to controlling the differential torque between shafts rotating at different rates, on a common axis.

The background to the device lies in the Achilles heel of the differential unit most commonly found on vehicles. The differential unit was designed to enable two independently rotating shafts, on a common axis, to be driven at different speeds :- i.e.

drive wheels when cornering.

The undesirable action of the device allows the input torque to follow the path of least resistance through the unit. Hence should a drive wheel loose traction it will tend to speed up at the expense of the other wheel with traction.

To try and control this, yet still maintain the basic action of the differential, various modification or adaptations of the differential unit have been devised i.e.

differential locks, limited slip differentials, viscous couplings, etc. They all tend to have built in characteristics that are not easily modifiable, and carry with them cost / size I weight / performance penalties.

Accordingly the present invention provides a means by which the different rates of rotation of the shafts are converted into a movement along the line of the common axis. The resulting unit should therefore be smaller and more compact than existing adaptations of the differential unit, hence giving much better cost / size / weight I performance ratios.

A specific embodiment of the invention will now be described by way of and example with reference to the accompanying drawings : Figl. shows a simplified view of the inner shaft. The shaft being spline at one end to locate the collar No.3 and yet allow it to slide along the common axis of the shafts.

Fig2. shows a simplified view of the end cap. This closes the open end of the outer sleeve No.4 and would cam the seals (not shown) while retaining any component parts or fluid contained within the body of the outer sleeve No.4.

Fig3. shows a simplified view of the collar No.3, with olily one track No.5. The collar locates on the inner shaft No.1 by means of the internal splines, and carries the track No.5 which forms a closed loop (i.e. the component part or parts within the track No. 5 will return to their starting point following sufficient rotation about the common axis).

Fig4. shows a simplified view of the outer sleeve. This lies on the same axis as the inner shaft No.l and collar No.3 and is connected to a second drive shaft.

FigS. shows an expanded I assembly drawing of the unit.

Fig6. shows a cross sectional view of the components in position relative to one another.

When both the inner shaft No.1 and outer sleeve No.4 are rotating at the same rate then the collar No.3 does not move along the common axis of the shafts. I4r, d.

When there is a difference in the relative rates of rotation of the inner shaft No.1 and outer sleeve No.4, the collar No.3 moves along the common axis of the shafts due to a component No.7 which is recessed into the track No.5 and has a fixed position relative to the body of the outer sleeve.

The rate and direction of the collar No.3 movement, back and forth along the common axis of the shafts, is governed by the shape or line of the track No.5 and the relative difference in rates of rotation of the inner shaft No.1 and the outer sleeve No.4.

To resist the axial movement of the collar No.3 the body of the unit is filled with a viscous substance or other suitable medium. axial movement of the collar No.3 forces this substance to be transferred from one side of the collar No.3 to the other: the greater the rate of axial movement the greater the effective resistance.

Bv controlling the axial movement of the collar No.3, the mechanism is controlling the difference in the relative rates of rotation of the inner shaft No.1 and the outer sleeve No.4. hence it will. also be controlling the difference in torque between the inner shaft No.l and outer sleeve No.4.

To enhance the operation of the mechanism additional components may be added to the unit and the design of the tracks altered, i.e.

As can be seen from Fig 3, the collar No.3 has a track No.5 which in its simplest form the line of the path could be said to be of an elliptical nature, with its main plane at an angle to the common axis of the shafts. In a more elaborate form, the line of the path being constructed from a multiple series of arcs.

To reduce individual point loads on the component parts within the constrained loop the number of tracks per collar could be increased, and / or design the track such that the component count moving within the constrained loop or system could be increased Multiple collars and varying angled tracks could be employed so that the device characteristics become more linear.

A controllable bypass could be added to the closed system so that the movement of a viscous substance or other suitable medium, within the unit, could be controlled externally.

In addition to or in place of the viscous substance or other suitable medium mechanical means, such as springs could be used or rubber pads etc.

Claims

1. A differential torque control system whereby the degree and rate of rotation of shafts or gears on a common axis, having different rates of rotation relative to each other, are controlled: - the control being sensitive to both the direction and difference in the relative rates of rotation of the shafts.

- the control being sensitive to a component or component parts moving within a constrained path which takes the form of a closed loop or system.

-the degree of sensitivity and control can be modified by changing the component part or parts which govern the constrained path.

-the degree of sensitivity and control is dependant upon the ease with which a component or component parts moves relative to the constrained path.

2. As claimed in claim 1. a differential torque control system where there is a component part or parts within the device which rotate at the same rate as a shaft or gear forming part or all of the mechanism which converts the difference in relative rates of rotation into movement along the line of the common axis of the shafts.

3. As claimed in claim 1. a differential torque control system whereby the control is achieved through hydraulic means.

4. As claimed in claim 1. a differential torque control system whereby the control is achieved through mechanical means

5. As claimed in claim 1. a differential torque control system whereby the control is achieved through pneumatic means

6. As claimed in claim 1. a differential torque control system whereby the control is achieved through electrical means

7. As claimed in claim 1. a differential torque control system whereby the control is achieved through a combination of means claimed in claims 3. 4. 5. and 6.