IMPROVEMENTS RELATING TO VARIABLE SPEED CONTROL DEVICES

AMELIORATION DE DISPOSITIFS DE COMMANDE A VITESSE VARIABLE

English Abstract

Individual sets of data control points are illustrated on a typical torque
profile of a brushless DC motor showing how the torque capability decreases
with increase of speed of the motor. Each set effectively corresponds to a
particular simulated gear setting for gear changes when driving a vehicle
powered by such an electric motor. The envelope defined by the data control
points for four "gear settings" are indicated by the reference numerals (I,
II, III, IIII). The control equipment for driving the motor can then only
operate within the particular set which is selected (by suitable programming
of an electronic control unit). When the user senses that he has reached
maximum speed under a particular set he can change to a new set and thus
effectively move up a gear. The reverse will of course apply if there is a
desire to decelerate. As the driver arranges to increase the speed of the car
to a maximum he will move up through each of the four gears unitl the maximum
available speed from the motor is achieved.

French Abstract

Sur une courbe type de couple de moteur c.c. sans balais, on porte des groupes séparés de points de commande de données indiquant la décroissance du couple en fonction de la vitesse. Chaque groupe correspond en fait à un point simulé de passage de vitesse lors de la conduite d'un véhicule utilisant un tel moteur électrique. L'enveloppe définie par lesdits points pour quatre rapports est indiquée par les chiffres de référence "I, II, III et IIII"; le dis positif de commande du moteur ne peut alors fonctionner qu'à l'intérieur du groupe donné ayant été sélectionné (par programmation adéquate d'une unité électronique de commande). Lorsque le conducteur perçoit avoir atteint la vitesse maximale dans un rapport donné, il peut sélectionner un nouveau rapport et passer dans une vitesse plus élevée. L'inverse se produit s'il désire décélérer et changer de vitesse. Lorsqu'il désire atteindre la vitesse maximale, il monte successivement les quatre rapports jusqu'à ce que le moteur tourne à son régime maximal.

Claims

5
CLAIMS
1. A system for creating a variable speed control for
the output drive of a DC electric motor wherein individual
sets of data control points on a torque to RPM speed profile
are predefined and set as operational parameters into
control equipment for driving the motor, such that the motor
can only be driven within the confines of the operational
envelope of any particular set, and switch means is provided
for switching between the separate sets of operational
parameters as desired.
2. A system according to Claim 1, wherein a variable
position acceleration control device is provided which is
able to create a signal related to the position of the
control device to determine the electrical current level
supplied to the motor.
3. A system according to Claim 2, wherein means is
provided to prevent switching between sets of operational
parameters whilst the acceleration control device is
creating an output signal.
4. A system according to any one of Claims 1 to 3,
wherein the sets of data control points are programmed into
an EPROM device.
5. A system according to any one of Claims 1 to 4,
wherein a reversion set of data control points defines
operational parameters for reverse drive of the motor.
6. A system according to Claim 5, wherein control

6
means is provided to prevent operation of the motor under
the operational parameters of said reversion set until the
motor has come to a standstill.
7. A system according to any one of Claims 1 to 6,
wherein a braking device is provided which, when operated,
will send control signals to the motor drive to cause
assisted regenerative braking of the motor.
8. A system according to the combination of Claims 2
and 7, arranged so that the signal sent from the braking
device will override any control signals delivered by said
acceleration control device.
9. A system according to any one of Claims 1 to 8,
including a display panel to indicate the current status of
control devices within the system.
10. A system according to any one of Claims 1 to 9,
including remote-control linkage apparatus connected to
modify the status of the control device within the system
upon receipt of signals from a remote-control operating
device.
11. A system for creating a variable speed control for
the output drive of a DC electric motor substantially as
herein described with reference to the accompanying draw-
ings.
12. Any novel combination of features of a system for
creating a variable speed control for the output drive of a
DC electric motor substantially as herein described and/or
with reference to the accompanying drawings.

Description

CA 02351561 2001-05-15
'WO 00/Z9248 PCT/CB99/03810
1
Improvements relating to Variable Soeed Control Devices
This invention is concerned with means for providing a
variable speed from a DC electric motor. Whilst the
invention is concerned particularly with means for
controlling the speed of a wheeled vehicle it is to be
understood that the device can equally be used for speed and
motion control purposes in relation to wheeled and tracked
vehicles, marine craft, aviation applications and mechanical
handling applications.
According to the present invention there is provided a
system for creating a variable speed control for the output
drive of a DC electric motor wherein individual sets of data
control points on a torque to RPM speed profile are prede-
fined and set as operational parameters into control
equipment for driving the motor, such that the motor can
only be driven within the confines of the operational
envelope of any particular set, and switch means is provided
for switching between the separate sets of operational
parameters as desired.
This system can be used in particular to simulate the
effect of gear changing in a conventional motor vehicle. It
is therefore particularly suited for installation into so
called "go-karts" which are provided for recreational and
competitive track driving. As the user gains speed he can
switch from one set of operational parameters to a new set
and thus simulate the effect of changing from a lower to a
higher gear. It is greatly preferred that the system should

CA 02351561 2001-05-15
WO 00/29248 ~ PC'T/GB99/03810
2
incorporate a variable position acceleration control device
which is able to create a signal related to the position of
the control device to determine the electrical current level
supplied to the motor. This control device can then be used
as a conventional accelerator when the system is incorpor-
ated into a vehicle. Ideally means will be provided to
prevent switching between sets of operational parameters
whilst the acceleration control device is creating an output
signal.
The system can be provided with a reversion set of data
control points which define operational parameters for
reverse drive of the motor. This enables a vehicle, in
which the system is incorporated, to be driven in reverse.
Preferably control means will be provided to prevent
operation of the motor under the operational parameters of
said reversion set until the motor has come to a standstill.
The system may also incorporate a braking device which,
when operated will send control signals to the motor drive
to cause assisted regenerative braking of the motor.
Preferably such a system would be arranged so that (when an
acceleration control device is provided) the signal sent
from the braking device will override any control signals
delivered by said acceleration control device.
In the preferred arrangement the sets of data control
points will be programmed into an EPROM device. The EPROM
device could be replaced by another in which alternative
sets of operational parameters can be defined. This enables
the overall control system to be modified, for example to

CA 02351561 2001-05-15
WO 00/2928 ~ PCT/GB99/03810
3
allow for the different circumstances present in a track
around which a vehicle might be driven. The system can then
be adapted for a variety of tracks, as required.
Ideally the system will include a display panel to
indicate the current status of control devices within the
system. It is also possible to provide a remote-control
linkage apparatus connected to modify the status of the
control device within the system upon receipt of signals
from a remote-control operating device.
A preferred embodiment of the invention will now be
described in more detail with reference to the accompanying
drawing which is a graph illustrating the torque/speed
profile of a DC electric motor.
The drawing illustrates a typical torque profile of a
brushless DC motor illustrating how the torque capability
decreases with increase of speed of the motor. One of the
major objectives of this invention is to provide a means of
simulating gear changes when driving a vehicle powered by
such an electric motor. This is achieved by defining
individual sets of data control points, wherein each set
effectively corresponds to a particular gear setting. The
envelope defined by the data control points for four "gear
settings" are indicated by the reference numerals I, II,
III, IIII. The control equipment for driving the motor can
then only operate within the particular set which is
selected (by suitable programming of an electronic control
unit). When the user senses that he has reached maximum
speed under a particular set he can change to a new set and

CA 02351561 2001-05-15
WO 00/29248 PCT/GB99/03810
4
thus effectively move up a gear. The reverse will or course
apply if there is a desire to decelerate. As the driver
arranges to increase the speed of the car to a maximum he
will move up through each of the four gears until the
maximum available speed from the motor is achieved.
Changing gear from one gear to the next can be achieved
by pressing switches on the steering wheel of the vehicle,
one being provided for upwards changing and the other for
downwards changing. A separate switch will be provided to
enable the system to operate in such a manner that the motor
is reversed (once it has achieved stationary condition),
thus providing a reverse "gear" for the vehicle.
The system can be operated so as to simulate an
automatic gear box. This can be achieved by placing zero
torque blips at specific points such that the drive reduces
no torque for a fraction of a second. This gives the
feeling of a gear change.
It will be appreciated that the system does not need to
be limited to four gear changes as the number can be
increased or decreased as desired.

Representative Drawing