HAND CONTROLS FOR DISABLED DRIVERSThis invention relates to hand control conversions from normal foot operated pedals for the brakes and/or throttle and/or clutch where the links between the pedals and the hand control arms are designed to allow the steering column to bend, collapse, telescope or be adjusted as was it was originally designed to do by the vehicle manufacturer. The hand controls are mounted on the steering column but link to the floor pedals using a multi-link mechanism in such a way that they do not interfere with the movement of the steering column allowed by the vehicle manufacturer. This has two important benefits over traditional column mounted hand controls.Firstly, SAFETY, whereby this invention allows the steering column to perform in a crash exactly as the vehicle manufacturer had designed it, and, secondly,ADJUSTABILITY, whereby the full range of adjustment to the position of the steering wheel, as, and if, originally offered by the vehicle manufacturer, is still available.
The improved safety aspects of this invention are considerable. Traditional hand control adaptations mainly use very similar designs where a rigid mounting point for the pivot is located to the left for right handed controls (for left handed controls which are a minority the principles are the same but the geometry is reversed) and underneath the steering column. This can either be attached to the steering column itself or to the fascia or dashboard. In either event this rigid mounting represents a hazard to the drivers knee or legs in the event of an accident. From this pivot a rigid bar runs underneath the steering column to the drivers right from where the controls are operated. Attached to this rigid bar are very strong bars or rods which are directly linked to the foot pedals.To operate the brake a push force exerted on the hand control lever is translated into a push force on the brake pedal through the linking bars or rods which need to be particularly strong and stiff since operating under compression.
However, this system has effectively directly linked the foot pedals to the top half on the steering column and has negated the vehicle manufacturer's design of the steering column which must, by law, limit the rearward movement of the steering wheel in the event of a frontal impact.
This invention, which will be described in greater detail later, uses a multiple pivot action to attach the hand control arm to the brake pedal. Within this mechanism is a link under tension for the operation of the brake. This link need not be as stiff or as strong as it would need to be under compression and can be intentionally engineered to break or bend when a reverse force is applied as would be the case if the brake pedal were to be pushed upwards in an accident.
The steering column is therefore able to collapse, bend or move as the manufacturer designed it to do without hindrance from the hand control system.
Also because this invention uses a multiple pivot action the mechanical advantage required for easy operation of the brake can be obtained in a more confined space than the traditional single pivot lever systems. With this invention it is possible to mount the pivot points centrally under the steering column reducing the dangers of contact with knees and legs in an accident.
With most vehicle designs it is also possible to conceal the mechanism within the steering column shroud which provides greater protection than the more exposed mechanism of traditional systems.
The adjustability aspect of this invention is rather more difficult to describe and will be explained in greater detail. The principles of the design are the same for a non-adjustable steering column but do not require as complicated a mechanism. The simplifications to a nonadjustable system will be described later.
Traditionally, hand controls for people with restricted lower limb functions have relied on an arrangement of fixed position rods and/or cables which translate movement of hand operated controls mounted on or beside the steering wheel into movements of the foot pedals. The method of mounting these controls on the steering column has required the steering wheel to be set in a single fixed position both in-and-out and vertically. For many disabled drivers the advantage of adjustability will be significant. The steering wheel can be positioned upwards and inwards to enable them to get in and out of the vehicle more easily and gives them more space to manoeuvre their legs manually. However, when in the normal driving position, the driver can then adjust the steering wheel to give the safest and most comfortable driving position, usually closer to the body.
This invention relates to a hand control conversion consisting of a system of strong, nonflexible, mechanical links and pivots which allows the steering wheel to be repositioned within the range of adjustability now commonly being offered by a number of vehicle manufacturers.
As the steering wheel is repositioned the mechanism of this system automatically adjusts the relationship between the hand and pedal movements when relocked in the desired position.
An alternative means to achieve this adjustability could be to use flexible links or cables but this would be unacceptable for safety reasons because of the potential breakage of such links or cables, especially when considering the brakes. Flexible links or cables are acceptable for throttle connections because failure here does not represent a serious safety problem.
The essence of this invention is that it uses strong, fixed, mechanical linkages to the brakes.
Such linkages can be solid rods, hollow tubes or flat bars but in the particular embodiment described herein are generally referred to as links. The technical advance made by this invention is that, as the steering column is moved from one position to another, links fixed to the upper and lower sliding parts of the column adjust, through the action of pivots, to maintain the relationship between the position of the hand control arm and the steering wheel whilst the position of the link to the brake pedal is unaltered.
Although this invention is concerned primarily with the adjustment of the steering column inwards and outwards, it can also incorporate adjustments upwards and downwards, tilt and in fact side to side (although this is unusual) by using ball type joints in the final linkage to the brakes.
The most common method of hand control is that a push action on a lever or ring operates the brakes and a pull action operates the throttle. Clutch operation on manual gearbox vehicles is usually achieved with an independent lever or electrically.
This invention retains this traditional operating technique where the control for the brake is by push action and the control for the throttle is by pull action although other types of operation such as a radial arm, a twist grip, a push action or other suitable action can be incorporated.
Push action for the brakes is preferred since this is safer because many disabled people may have insufficient strength to pull hard enough, quickly enough, in an emergency. Push strength is usually greater. Clutch operation when using a lever would usually be a push action to engage the clutch an therefore follows the same principles as the brakes as described herein.
A specific embodiment of the invention will now be described by way of an example with reference to the accompanying drawings in which:FIGURE 1 shows, in perspective, the overall layout of the hand control system inrelation to the steering column and wheel.
FIGURE 2 illustrates the steering column with the steering wheel in a short length ofits adjustment.
FIGURE 3 illustrates the steering column with the steering wheel in a longer length ofits adjustment.
FIGURES 4 & 5 are a diagrammatic representation ofthe geometry involved.
Referring to the drawings, with the steering wheel fixed in any position, a push force exerted on control arm 1 of Figure 1 through the action about pivot point 2 produces a pull force on link 3. This is translated through the action about pivot 4 into a push force on link 5 resulting in depression of the brake pedal 6. A pull force on control arm 1 gives, through the same action about the pivots, a pull force on link 5. Link 5 is a composite of a rod within a tube whereby in compression, as when operating the brake pedal, it is of a fixed minimum length.
However, when required to operate the throttle pedal through a pulling force on control arm1, the link will slide within the tube 7 and through linkage 8 a pull force will be exerted on the back of the throttle pedal and thereby the throttle is operated. Linkage 8 can be either a flexible cable system as shown in Figures 2 and 3 or could be a system of non-flexible rods, bars, tubes and pivots.
Referring to Figures 2, the steering wheel is shown in a short position of adjustment which has been achieved by releasing clamp 9 on the steering column and sliding the upper section 10 over the lower section 11 until the desired position is reached at which point the steering wheel adjustment is locked by tightening clamp 9.
In this position it can be observed that the distance between joint 12 and the pedal attachment joint 13 is fixed and governed by the length of link 5 in its minimum position.
Figure 3 shows the steering wheel moved and locked in a longer position of adjustment.
Although the overall distance between the steering wheel (and consequently the hand control arm 1) and the foot pedals is now greater than in Figure 2, it is observed that the distance between joint 12 and joint 13 remains the same and is governed by the length of link 5. In other words, the moving of the steering wheel outwards has not interfered with the positioning of the brake control link to the pedal.
In order to maintain the same relationship between the position of the hand control arm 1 and the steering wheel 15 as indicated by the distance 14 in Figure 2, it is necessary that as the steering column is adjusted, pivot 4 is moved in correspondence to the distance travelled. This is achieved, in this particular embodiment of the invention, by linking pivot 4 to another arm which is attached to the fixed, lower part of the steering column through joint 16 and through joint 17 and link 18 to the upper, moveable part of the steering column. It can be observed that because of this linkage, pivot 4 shall move as the steering column is adjusted whereas the angle between link 3 and the control arm 1 is unchanged and thereby distance 14 remains the same.
To demonstrate this principle more clearly observe Figures 4 and 5 which give a simplified diagrammatic representation of the geometry involved in the adjustment of the steering wheel position. Figure 4 represents the steering column in a short position of adjustment and Figure 5 in a long position of adjustment. If points 12 and 13 are aligned between Figures 4 and 5, it can be observed that when point 4 is moved from its position in Figure 4 to its position in figure 5 as the steering wheel 15 is moved outwards, points 12 and 13 remain fixed. The angle between lines 1 and 3 is the same therefore distance 14 is unaffected. Point 16 has not changed since fixed to the lower part of the steering column.Point 18 is fixed to the upper part of the column and as the two parts are moved apart, as from Figure 4 to Figure 5, the angle between points 16 and 18 (at point 17) changes in correspondence to the distance travelled and to the same extent as the angle between point 12 and line 3. The effect is that the total distance travelled is taken up by the change of angle between point 12 and line 3 and neither the distance between the hand control arm and the steering wheel (distance 14) nor the distance from the bottom part of the adjustment system to the brake pedal (the length of line 5), have changed.
With regard to the vertical adjustment of the steering wheel position or other lateral adjustments, this is more simply achieved by making joints 12 and 13 ball or swivel type assemblies. This means that when the steering column is moved up or down (or sideways) from its original position the joints at both ends ofthe brake push link 5 are free to move in a vertical (or horizontal) plane and thus the operation of the hand control mechanism is unaffected by such adjustments.
The above embodiment of the invention relates to vehicles in which the manufacturer has designed adjustability for the position of the steering wheel. The system described also has the advantage that the free movement it offers in relation to the movement of the steering column is that the collapsibility of the column in a crash situation is unaffected and the vehicle manufacturer's safety design criteria are not compromised.
For vehicles where the manufacturer has not incorporated the facility of being able to adjust the steering wheel position in any direction the design can be simplified but still retains the safety aspects whereby the column will perform in a crash as the manufacturer designed it to do without hindrance from the hand control system. Since the column will be in a fixed position there is no need to include the mechanism which maintains the fixed relationship between the hand control arm and the steering wheel as the column is adjusted. Link 18, pivot 17 and the link joining this to joint 16 are not required.To ensure that the steering column will collapse, bend and move in a crash situation as the vehicle manufacturer designed it, Link 3 shall have a weak point intentionally engineered in it which will fail when a reverse force is applied up from the brake pedal or when a force is applied to the steering column. As described earlier, traditional hand control mechanisms operate with the brake control links in compression and therefore require to have strong, stiff rods or bars. When a reverse force is applied to such links they will not readily bend or break and therefore the vehicle manufacturer's safety design of the steering column in an accident is severely compromised.
With this invention the link between the upper and lower parts of the steering column works in tension during normal braking function and can be designed to bend, break or absorb shock forces in compression which will occur either when the brake pedal is push backwards towards the driver or when the driver strikes the steering wheel. Since this link can also be used in compression for the operation of the throttle the type of weak point needs to be individually selected for different vehicle types with regard to forces required to operate the throttle and forces at which the steering column has been designed to move in a crash situation. Since the latter force will inevitably be much smaller than the former this weak point will not fail during throttle operation but will be engineered to fail at forces much less than the forces at which the column has been designed to move.