Title of Invention

AN ACCELERATOR PEDAL DISCONNECTION MECHANISM FOR VEHICLE SPEED LIMITER

Abstract A device for disabling the manual accelerator control of a vehicle when electrical power to it is discontinued, comprising a friction drum keyed to an output shaft and thence to a crank linked to the speed control system of the vehicle; a spring metal band wound on the said drum, the first end of the band being connected to the spring arm fixed to the accelerator pedal shaft; a solenoid for anchoring the second end of the band relative to the drum when it is energized so that in this state depressing the accelerator pedal of the vehicle would cause the band to tighten around the drum and force it to rotate with the accelerator pedal shaft, causing it to rotate the crank thereby allowing the accelerator pedal action to control the speed of the vehicle; and such that when the solenoid is de-energized the second end of the band being free of its attachment to the friction drum, the band would not bind on to the drum and so would effectively disconnect the accelerator pedal from the linkage to the vehicle's speed control; though however on further rotation of the pedal shaft the armature arm being pulled along via the band will once again connect with the solenoid arm after a certain travel by a boss on the armature arm engaging a hook on the solenoid arm and then the band again binds on the friction drum forcing it to follow the accelerator pedal in its further travel, which enables the vehicle to be driven at a slow speed despite the solenoid being de-energized.
Full Text

This invention relates to an electromechanical device for disabling the accelerator control on a vehicle in response to the termination of electrical power to it. More particularly, though not exclusively, this invention is used as part of a system for enforcing a speed limit for road vehicles. In speed limiters known to the art, the accelerator disabling mechanisms are not very reliable, their main drawback being a tendency to jam in such a manner as to defeat the very purpose of the equipment.
On the other hand, apart from the main objective of achieving reliable disconnection of the accelerator control, and thus preventing the driver from over-speeding; this invention has the following features:-
It disables the manual accelerator control pedal electrically.
The design makes for very low electric power drain.
The driver is unable to bypass the device.
The device does not in any manner adversely affect the performance of the
vehicle when the speed is within the prescribed limit.
It enables the driver to regain speed control once the speed has dropped below
the prescribed limit.
In the event of system failure the design enables the driver to continue driving;
albeit at a low speed.
It is adaptable for use in different types of vehicles.
The device for disabling the accelerator control of a vehicle, according to this invention, comprises a friction drum whose rotation is linked to the speed control of the vehicle via a series of links, a spring metal band wound on the drum, the first end of the band being fixed to a spring arm and thence to the accelerator pedal shaft, while the second end of the band is fixed to an armature arm carrying the armature which will be attached to a solenoid fixed to the friction drum when the solenoid is energized by its magnetic attraction, and detached when the current to the solenoid ceases. This mechanism causes the depressing of the accelerator pedal to tighten the band on to the friction drum when the solenoid is energized and rotate it and thus control the speed of the vehicle; on the other hand when the solenoid is de-energized the second end of the band is no longer fixed relative to the drum and so the accelerator pedal is no longer able to rotate the friction drum. However further depression of the accelerator pedal causes the spring band to rotate the armature carrying arm until a boss on it engages a hook fixed to the friction drum, whereupon the band again tightens on the friction drum (even though the solenoid is not energized,) causing it to turn with the further rotation of the pedal shaft. Thus when the solenoid is energized the pedal can move the drum through its full travel while when the solenoid is not energized the initial portion of the pedal movement cannot rotate the drum and so reduces the travel of the drum. As a result when the solenoid is de-energized only slow speed travel is possible.

This invention will now be described in further detail by reference to the accompanying drawings which illustrate, by way of example, and not by way of limitation one of the possible embodiments of this invention, wherein:-
Figure 1 illustrates an exploded view of the embodiment. Figure 2 illustrates the mechanism in the solenoid de-energized mode. Figure 3 illustrates the mechanism in the solenoid energized mode. Figure 4 illustrates the features of the armature arm!
The accelerator pedal is attached to a pedal shaft, which it turns through a small angle when pressed. The spring arm is keyed to the pedal shaft and rotates with it. A steel spring band has one end attached to the end of the spring arm. The steel band is further wound on a hard rubber friction drum. The friction drum has a steel core to which it is bonded. The output shaft is keyed to the said core of the friction drum. The output shaft has a crank attached to it which in turn is connected to the linkage on the vehicle which controls the speed of the engine. The other end of the steel band is fixed to the armature arm which can rotate relative to the friction drum about its axis. The armature is hinged to the armature arm such that it can rock through a limited angle relative to the armature arm. The solenoid is fixed to the solenoid arm which in turn is fixed to the friction drum core.
When the accelerator is not pressed a return spring holds it in the datum position; and in this position the armature touches the solenoid pole pieces. The ability of the armature to rock on the hinge pin on the armature arm ensures that the entire faces of the solenoid pole pieces contact the armature. Now if the solenoid is energized the armature sticks to the solenoid thereby fixing the armature arm, and the end of the steel band attached to it; to the friction drum. In this state when the accelerator pedal is pressed, the pedal shaft is rotated and along with it the spring arm to which the first end of the steel band is fixed. This tightens the steel band on to the friction drum and causes it to rotate with the pedal shaft and so rotate the output shaft keyed to it carrying the final actuating crank linked to the vehicle speed control linkages.
On the other hand when the solenoid is not energized, movement of the pedal would just rotate the armature arm via the steel band because the end of the steel band would no longer be fixed relative to the friction drum as the armature is not held by the solenoid. The band would not bind on to the drum and so the pedal is effectively disconnected from the output shaft. However after the armature arm has rotated through a certain angle the boss on it will contact the hook on the solenoid arm (see fig.2) and it is again fixed to the friction drum. Further rotation of the pedal shaft would bind the band on to the friction drum and cause it to rotate with the pedal shaft. Thus even when the solenoid is not energized the accelerator can rotate the final crank on the output shaft through a

limited angle. This would be sufficient to give the vehicle a speed of about 35 kmph in top gear.
In other words, when the solenoid is energized, the accelerator pedal can rotate the output crank through its full range of movement and so gives the driver full control of the speed of the vehicle. However if due to system failure the solenoid cannot be energized, it is still possible to drive the vehicle at a slow speed and avoid getting stranded.
In normal operation when the speed exceeds the prescribed limit and the system switches off the solenoid current, the driver has to just lift his foot off the accelerator pedal and the return spring would cause it to go back to its datum position, thereby once again the armature would contact the pole pieces of the solenoid. As soon as the speed limiting system senses the speed of the vehicle to have dropped below the prescribed limit it re-energizes the solenoid and the driver once again regains control of the speed.
The solenoid power can be kept low due to two factors of the design. One is the force amplification possible due to the friction of the band on the friction drum; thanks to which the force on the end of the band attached to the armature arm is of the order of 1/100 of the force applied on the end attached to the spring arm. Secondly the solenoid is not required to pull the armature across an air gap, but only to hold it in the zero air gap position.
On the other hand when the solenoid is not energizes the armature and the armature arm to which one end of the steel band is anchored is free from the solenoid arm and the friction drum, and so the steel band cannot bind on the friction drum until the boss on the armature arm is constrained mechanically by the hook on the solenoid arm.
The electrical power is supplied from the speed limiter system electronics in the form of an alternating current, which goes through a blocking transformer and full bridge rectifier within the mechanism casing before feeding the DC solenoid. This prevents attempts to bypass the system by energizing the solenoid directly from the battery.
The terms and expressions herein are of description and not of limitation, there being no intention of excluding any equivalents of the features illustrated and described, but it is understood that various other embodiments of this invention are possible without departing from the scope and ambit of this invention.












We Claim:
1. A device for disabling the manual accelerator control of a vehicle when electrical power to it is discontinued, comprising a friction drum keyed to an output shaft and thence to a crank linked to the speed control system of the vehicle; a spring metal band wound on the said drum, the first end of the band being connected to the spring arm fixed to the accelerator pedal shaft; a solenoid for anchoring the second end of the band relative to the drum when it is energized so that in this state depressing the accelerator pedal of the vehicle would cause the band to tighten around the drum and force it to rotate with the accelerator pedal shaft, causing it to rotate the crank thereby allowing the accelerator pedal action to control the speed of the vehicle; and such that when the solenoid is de-energized the second end of the band being free of its attachment to the friction drum, the band would not bind on to the drum and so would effectively disconnect the accelerator pedal from the linkage to the vehicle's speed control; though however on further rotation of the pedal shaft the armature arm being pulled along via the band will once again connect with the solenoid arm after a certain travel by a boss on the armature arm engaging a hook on the solenoid arm and then the band again binds on the friction drum forcing it to follow the accelerator pedal in its further travel, which enables the vehicle to be driven at a slow speed despite the solenoid being de-energized.
2. A device as claimed in claim 1 wherein a spring arm is keyed to the pedal shaft and rotatable therewith, one end of the said band being attached to it at its extremity away from the pedal shaft.
3. A device as claimed in claim 1 or claim 2 wherein the said drum has a metal core along its axis to which it is bonded.
4. A device as claimed in any one of the preceding claims wherein the solenoid is fixed to a solenoid arm which in turn is fixed to the said drum.
5. A device as claimed in claim 3 and claim 4 wherein an output shaft is keyed to the core of the drum.
6. A device as claimed in claim 5 wherein the output shaft is attached to the crank.
7. A device as claimed in any one of the preceding claims wherein an armature arm is mechanically free to revolve about the said drum axis.

8. A device as claimed in claim 7 wherein the armature is free to rock
through a small angle about a hinge pin on the armature arm so as to
ensure that it engages the entire area of the pole pieces on the solenoid
when the armature and solenoid come together.
9. A device for disabling the accelerator pedal speed control on a vehicle
substantially as herein described with reference to, and as illustrated in
the accompanying drawings.


Documents:

1721-che-2007 amended pages of specification 10-08-2011.pdf

1721-che-2007 examination report reply received 10-08-2011.pdf

1721-che-2007 claims.pdf

1721-che-2007 correspondence others.pdf

1721-che-2007 description (complete).pdf

1721-che-2007 drawings.pdf

1721-che-2007 form-1.pdf

1721-che-2007 form-18.pdf

1721-che-2007 form-26.pdf

1721-che-2007-claims.pdf

1721-che-2007-correspondnece-others.pdf

1721-che-2007-description(complete).pdf

1721-che-2007-drawings.pdf

1721-che-2007-form 1.pdf

1721-che-2007-form 26.pdf

1721-che-2007-others.pdf


Patent Number 249693
Indian Patent Application Number 1721/CHE/2007
PG Journal Number 45/2011
Publication Date 11-Nov-2011
Grant Date 03-Nov-2011
Date of Filing 06-Aug-2007
Name of Patentee CENTRE FOR DEVELOPMENT OF ADVANCED COMPUTING
Applicant Address VELLAYAMBALAM, THIRUVANANTHAPURAM, 695033, KERALA, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 DEVAKI KRISHNA WARRIER CENTRE FOR DEVELOPMENT OF ADVANCED COMPUTING VELLAYAMBALAM, THIRUVANANTHAPURAM, 695033, KERALA, INDIA
PCT International Classification Number B60W40/10
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA