Note: Descriptions are shown in the official language in which they were submitted.
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"Electric toy vehicle with improved grip"
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DESCRIPTION
The present invention relates to the sector of electric toy vehicles
which are typically intended for transporting children while playing. In
particular, the present invention concerns an electric vehicle which has
numerous advantages owing to improved grip of the driving wheels on
the rolling surface.
For some years various electric toy vehicles which reproduce, on a
small scale, cars, motorcycles, scooters or the like, have been known.
These known vehicles comprise at least two wheels, a seat (or saddle,
in the case of scooters and motorcycles) and a metal or plastic frame.
The vehicles present on the market essentially consist of three types.
The first type is a single-speed vehicle composed of: two or more blown
high-density polyethylene (HDPE) wheels; an electric motor; a reducer;
a wiring system; and a 6 V power supply battery. The second type is a
vehicle with more than one speed, composed of two or more blown
HDPE wheels; two motors, two corresponding reducers; a wiring
system; a 12 V power supply battery; and a thermal resistance for
reducing the speed and for preventing possible overloads. The third
type is a vehicle with more than one speed composed of two or more
blown HDPE wheels; two motors; two reducers; a wiring system; two 6
V batteries; a commutator for connecting the batteries in series or in
parallel in order to control the speed; and a system for controlling the
overload by means of inductance.
It is known that models with more than two driving wheels, for which
a corresponding number of motors/reducers are used, are available on
the market.
The Applicant has realized that the electric toy vehicles of the known
type have various drawbacks and limitations.
CONFIRMATION COPY
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As regards two-speed vehicles, it is pointed out that, in vehicles of
the second type, which are equipped with a 12 V battery, the speed is
controlled by a thermal resistance which results in wastage of power.
In vehicles of the third type, however, the speed is controlled by a
commutator which allows the two batteries to be used, depending on
the speed set, at 6 V or 12 V. It follows that the actual power
consumption is strictly related to the operating speed. It must also be
pointed out that, if, in the vehicles of the second type, there is a limited
operational autonomy precisely because of the management: system
used, in the vehicles of the third type the solution used to solve the
same problem results in increased costs owing to the use of two
batteries and a more complex wiring system.
The Applicant has established that the known electric toy vehicles
have poor or even zero grip when the vehicle is placed on surfaces
which are substantially smooth (for example marble floors, tiled floors,
etc.), on moist surfaces (grass lawns) or the like. As a result, the
known vehicles, from the standing position, start with extreme difficulty
and in any case struggle to keep to the steering path imposed by the
driver.
The Applicant has also noted that the wheels of the known vehicles,
which are made of internally hollow rigid plastic act like a sound box
and amplify the noise during movement of the vehicle, in particular in
closed surroundings. As a result, the use of the electric toy vehicle is
particularly noisy, in particular in surroundings which are substantially
closed or in any case confined.
Moreover, the Applicant has found that the wheels of the vehicle,
which are substantially rigid, transmit jerks and jolts when passing over
rough ground and greatly limit the comfort on-board.
In addition, the traction obtained with the use of a single motor and
with the wheels currently used results in various difficulties. Moreover,
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a high power consumption and rapid and non-uniform wear of the
wheels occurs.
Any attempt to overcome the abovementioned problems with the use
of several motors, several reducers and several batteries achieves
improvements but at the same time results in a reduction in the
operational autonomy and an increase in the cost of the product. The
problem of grip is amplified if the traction of the vehicle is obtained by
using two motors since, when the vehicle performs a turning movement,
one of the two motors suffers a braking action due to the friction. As, a
result, the vehicle loses its residual adherence; does not keep to the
steering path and the radius of curvature increases. This results in a
limited possibility of using the vehicle in unsuitable surroundings as well
as a difficulty in reversing the direction of travel. Therefore, if, as
usually occurs, the known vehicles are used in confined spaces, they
are affected not only by premature wear of the wheels, but in particular
of the motors and the batteries which are subject to the stress resulting
from continuous braking and from the need for continuous changes in
direction.
Paradoxically, when the basic structure of the rolling surface is able
to offer good adherence (for example, soft rubber surfaces, carpets or
the like) the starting up and stopping operations in the case of a known
vehicle are excessively sudden, violent and "unpredictable". In fact,
power is supplied (or interrupted) suddenly (compared to poor grip
situations where the wheels tend to spin) and the driver is unprepared
for these sudden acceleration or deceleration situations. For this
reason, the driver runs the risk of suffering knocks against parts of the
vehicle, in particular against the dashboard and the steering wheel, and
of suffering bruising.
The Applicant has noted the abovementioned limitations and has set
themselves the object of providing an improved electric toy vehicle
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which is safer and more comfortable compared to the present vehicles
of the same type, while maintaining low costs (even lower than those of
the present vehicles).
These and other objects are obtained by an electric toy vehicle
having the characteristic features described in Claim 1 and by a system
for controlling an electric toy vehicle according to Claim 20. The
dependent claims specify further advantageous characteristic features
of the invention. All the claims are considered to form an integral part
of the present description. .
According to a first aspect, the present invention relates to an electric
toy vehicle comprising: an electric motor, a speed reducer, a power
supply battery for powering said electric motor and moving the vehicle,
and at least two wheels, at least one of which is a driving wheel,
characterized in that at least one of the wheels has ~a coefficient of
friction greater than about 0.35, preferably greater than about 0.5 and
even more preferably ranging between about 0.5 and about 3Ø
Conveniently, said at least one wheel having a coefficient of friction
greater than about 0.35, preferably greater than about 0.5 and even
more preferably ranging between about 0.5 and about 3.0 is a driving
wheel.
Preferably, said at least one wheel having a coefficient of friction
greater than about 0.35, preferably greater than about 0.5 and even
more preferably ranging between about 0.5 and about 3.0 comprises a
rim and a tyre, where said tyre is a tyre comprising a rubber carcass.
Conveniently, said rubber carcass comprises two cross plies.
Preferably, said cross plies comprise cords made of nylon or the like.
Preferably, said tyre comprises a tread with a raised pattern.
Preferably, the thickness of the carcass in the sidewall zone ranges
between about 1.0 mm and 4.5 mm, more preferably between about
2.0 mm and 3.8 mm, and even more preferably between about 2.5 mm
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and about 3.3 mm.
According to an advantageous embodiment, said tyre has a size,
expressed in inches, of 10.00 X 5.00 - 5"1/2 (corresponding, in mm, to
260 X 120 - 5"1-2). According to a further embodiment, said tyre has a
size, expressed in inches, of 13 X 6.00 - 7" (corresponding, in mm, to
330 X 150 - 7"). According to yet another embodiment, said tyre has a
size, expressed in inches, of 15 X 7.00 - 8"1/2 (corresponding, in mm,
to 380 X 180 - 8"1/2).
Preferably, said. at least one wheel having ,a coefficient of friction
greater than about 0.35, preferably greater than about 0.5 and even
more preferably ranging between about 0.5 and about 3.0 comprises an
inner tube and an associated valve.
According to one embodiment, said vehicle comprises an electronic
control system, which is typically an electronic board, designed to ,
regulate the power supply voltage to the motor, for example by means
of a potentiometer or a similar device.
Conveniently, said electronic control system also comprises means
for regulating the acceleration in a predetermined manner substantially
independently of the load transported by the vehicle, in accordance with
a suitable acceleration ramp.
Conveniently, said electronic control system also comprises means
for regulating the deceleration in a predetermined manner substantially
independently of the load transported by the vehicle, in accordance with
a suitable deceleration ramp.
Conveniently, said electronic control system also comprises short-
circuiting means for managing the motor braking function.
Conveniently, said electronic control also comprises means for
controlling the direct current flow and preventing current peaks affecting
the motor, for example when starting and reversing.
Conveniently, said electronic control system also comprises means
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able to disable the functions of the vehicle at predefined overload
values, so as to avoid, for example, unsuccessful attempts by a vehicle
to overcome an obstacle, for example a wall.
Conveniently, said electronic control system also comprises means
for limiting complete discharging of the power supply battery.
Conveniently, said electronic control system also comprises means
for electronically disabling the functions of the vehicle during recharging
of the battery.
Conveniently, said electronic control system also comprises means
for indicating the state of charging of the battery, for example by means
of a display or the like.
The solution adopted allows the optimum use of the vehicle
resources as well as maximum use in terms of operating autonomy,
such that the wiring system uses, for power functions, wires with a
cross-section of about 2.5 mm2, while for the signalling functions the
cross-section of the wires is reduced to about 0.5 mm2.
The present invention will certainly become clear from the detailed
description which follows, provided by way of a non-limiting example, to
be read with reference to the accompanying illustrative plates of
drawings, in which:
- Figure 1 shows the layout of the transmission of an electric toy
vehicle of the first known type, having one speed;
- Figure 2 shows the layout of the transmission of an electric toy
vehicle of the second known type with more than one speed;
- Figure 3 shows the layout of the transmission of an electric toy
vehicle of the third type with more than one speed;
- Figure 4 shows a layout of the transmission of an electric toy
vehicle according to the present invention;
- Figures 5a and 5b show cross-sections through a tyre according to
the present invention and a known tyre for agricultural use;
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- Figure 6 shows schematically an electronic control system
according to the present invention.
The same reference numbers will be used to indicate the same parts
or components which are functionally equivalent.
Figures 1, 2 and 3 show three layouts of the transmissions of
respective electric toy vehicle of the known type. The first layout is
generally used in toy vehicles which are recommended for little
children. The second and the third layouts are generally used in toy
vehicles which allow transportation of one or more passengers. It is
useful to clarify henceforth that the term "electric toy vehicle" (or
equivalent terms) shall be understood in this connection as referring to
any vehicle with two, three or four (or more) wheels, which is powered
by direct current at 6 V (or 12 or 24 V), recommended (depending on
the models and the drive system) for children having an age of between
about two years and ten years.
The layout according to Figure 1 provides for a motor 1 which is
powered by a (6 V) battery 2 and a speed reducer 3 (shown in an
exploded view) which is connected to a wheel 4 (driving wheel). The
wheels 4 and 5 are both made of HDPE and have a coefficient of
friction, at room temperature, ranging between 0.08 and 0.2 measured
in accordance with the Standard ASTM D1894 "Standard Test Method
for Static and Kinetic Coefficients of Friction of Plastic Film and
Sheeting" . The layout according to Figure 1 also shows a pedal-
operated switch P and a device 1 for reversing the direction of travel.
The layout according to Figure 2 provides for two motors 1, which
are powered by a single (12 V) battery 2, and two corresponding speed
reducers 3 (shown in an exploded view) which are connected to
respective wheels 4 and 5. The wheels 4 and 5 are made of HDPE and
have a coefficient of friction, at room temperature, ranging between
0.08 and 0.2 measured in accordance with the Standard ASTM D1894.
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The layout according to Figure 2 also shows a pedal-operated switch P,
a device I for reversing the direction of travel and a selector for
changing gear.
The layout according to Figure 3 provides for two motors 1 which are
powered by two respective (6 V) batteries 2 and two corresponding
speed reducers 3 (the right-hand one shown in an exploded view)
connected to respective wheels 4 and 5. The wheels 4 and 5 are made
of HDPE and have a coefficient of friction, at room temperature,
ranging between 0.08 and 0.2, measured in accordance with the
Standard ASTM D1894. The layout according to Figure 2 also
illustrates a pedal-operated switch P, a device I for reversing the
direction of travel and a selector M for changing gear. The selector M
also comprises a commutator for connecting the batteries in series or
parallel in order to control the speed. The layout according to Figure 3
also comprises a device 6 for controlling the overload by means of
inductance.
The layouts according to Figures 1, 2 and 3 all have the problems
r~°
and the limitations listed in the introductory part of the present
description.
A layout of the transmission of an electric toy vehicle according to
the present invention is shown in Figure 4.
The layout according to the present invention comprises an electric
motor 11, a (12 V) batfiery 12 for powering the motor 11 and a speed
reducer 13 which transmits the movement to a wheel 14. Unlike the
known layouts, at least the wheel 14 connected to the speed reducer
(but preferably also the other wheels 15 of the vehicle) is substantially
soft and has a coefficient of friction greater than about 0.35, preferably
greater than about 0.5 and even more preferably ranging between
about 0.5 and about 3Ø Depending on the specific use of the vehicle,
the coefficient of friction may, in particular, range between about 0.5
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and 1.0, between about 1.0 and 1.5, between about 1.5 and 2.0,
between about 2.0 and 2.5 or between 2.5 and 3Ø Tyres with
coefficients of friction greater than 3.0 are also possible, in particular
when it is envisaged using the vehicle on particularly smooth and
slippery surfaces.
Figure 5a illustrates, by way of example, a cross-section through an
embodiment of a tyre 141 of a wheel 14 according to the present
invention. The tyre 5a has a size 10 X 5.00 - 5"1/2 (corresponding, in
mm, to 260 X 120 - 5"1/2). The first number indicated represents the
outer diameter, the second number represents the cross-section and
the third number represents the fitting diameter generally always
expressed in inches. Figure 5b instead shows a cross-section through
. a tyre available on the market for agricultural use. The tyre according
to Figure 5b is produced under the trade name "DURO" and~has a size
of 11 X 4.00 - 5". The tyre 141 according to the present invention
comprises a carcass and two sidewalls which terminate in respective
beads. Preferably, the tyre also comprises a tread with radially
projecting blocks and grooves for a greater grip of the vehicle. The
carcass is formed by two cord cross plies. Preferably the cords are
textile or nylon cords arranged with a density comparable to that of a
bicycle tyre or the like. Figures 5a and 5b shows some significant
dimensions of the two tyres compared. In particular, the carcass
thickness of the tyre according to Figure 5a along the sidewalls is about
3 mm, while that of Figure 5b is about 7 mm.
The recorded weight of the known tyre (Figure 5b) is about 1.875 kg,
while the weight of the tyre according to the invention (Figure 5a) is less
than half and equal to about 0.85 kg. Therefore, the comparison has
shown how a tyre which equips a vehicle according to the present
invention is much lighter and more economical than a similar known
tyre for agricultural use. The characteristic feature of lightness is very
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important since an electric toy vehicle must be light in order to have
acceptable performance features and limit the wear of the motor and
consumption of power by the battery. The characteristic feature of
economy is also very important in vehicles of this type and is due
mainly to the saving of rubber material (reduced thickness of carcass)
and to the consequent shorter vulcanization times.
According to a preferred embodiment, each tyre 141, 151 is mounted
on a rim 143, 153, for example made of plastic, composite material or
metal, with an inner tube (not shown). According to an alternative
embodiment, the tyre 141, 151 is of the tubeless type, i.e. without an
inner tube. This second embodiment requires a greater precision in
machining of the rim and is therefore less preferred.
The fact of having equipped the vehicle with a driving wheel having a
coefficient of friction greater than about 0.35, preferably greater than
about 0.5 and even more preferably ranging between about 0.5 and
about 3.0 has enabled substantially all the problems of the known art
indicated above to be overcome. Firstly, a vehicle according to the
invention is easier to start from standstill and easier to keep along the
steering path of the driver. It has also solved the problems associated
with the noise of the wheels on the rolling surfaces. Moreover, the
travel comfort is much improved owing to the softness of the tyres
compared to the rigid wheels of the known vehicles.
The wear of the tyres is practically negligible and in any case
substantially uniform also without using two separate motors.
According to a particularly advantageous embodiment, the motor 11
is managed by means of a special control system 17.
The fact of using a single electronically managed motor, associated
with tyres having a coefficient of friction greater than about 0.35,
preferably greater than about 0.5 and even more preferably ranging
between about 0.5 and about 3.0 greatly improves the drivability of the
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vehicle and allows use thereof also in relatively confined spaces. The
Applicant, in fact, has noted a significant reduction in the minimum
steering radius compared to the known electric toy vehicles, namely
from about 2.0-3.0 m (for a known four-wheel vehicle) to about 0.5-1.5
m (for a similar vehicle according to the invention).
According to a first aspect, the control system 17 is able to regulate
the power supply voltage to the motor and therefore the speed of the
vehicle. The electronic control system 17 preferably consists of an
electronic power and signalling board.
As shown schematically in Figure 4, the control system 17 co-
operates with one or more of the following devices: a pedal-type switch
P, a key-operated switch C, a device 1 for reverse travel, a selector M
for changing gear M; an acoustic device A (horn or the like); a display
VB for charging the battery; one or more illumination lamps (front LH
"LA_SX", front RH "LA DX", rear LH "LPlSX" and rear RH "LP~DX");
and a socket 182 for recharging the battery. Conveniently, the
electronic control system 17 is programmed so that the motor receives
predetermined fractions of the maximum voltage which can be supplied
by the battery. For example, if the maximum voltage which can be
supplied by the battery is 12V, the electronic control system may be
programmed so as to supply to the motor a first fraction of 3 V, a
second fraction of 6 V, a third fraction of 9 V or the whole voltage of 12
V.
The supplying of these voltage fractions may be controlled by the
driver (child), may be factory-set, may be determined by an adult or
may be a combination of the abovementioned options. 1n the first case,
the child will have access to a speed selector and will be free to choose
the speed which is most suited to the circumstances. In the second
case, it will be the manufacturer who determines the maximum speed
for each type or category of vehicle (this means that, while maintaining
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the same components, it is possible to construct electric toy vehicles for
children who are less expert or for older children). Alternatively, the
setting is left to an adult, providing a first selector in a zone which is
inaccessible for the child and, if necessary, a second selector which
can be operated by the child/driver. This solution is advantageous
because it allows an adult to set the maximum permitted speed of the
vehicle depending on the age and the actual abilities of the child.
Preferably, said electronic control system 17 is programmed so as to
provide a predetermined acceleration ramp 171 independent of the
load transported by the vehicle. Figure 6 shows an embodiment of an
acceleration ramp 171 and deceleration ramp 172. Figure 6 also
shows a reversing travel ramp 173. According to the present invention,
the maximum speed of the electric toy vehicle (of the order of 8-10'
km/h) is reached after a certain time interval (of the order of 3-4
seconds). According to the ramp shown in Figure 6, the acceleration of
an electric toy vehicle starting in 4t" gear (selector in position 4) is the
same as a vehicle which starts in 1St, 2nd or 3"~ gear; the difference lies
in the maximum speed which can be reached without making further
gear changes. The same concept applies to the deceleration phase.
In any case, the acceleration or the deceleration of the vehicle
according to the present invention is independent of the load
transported. This solves a very common problem in the known electric
toy vehicles where the smaller the weight (i.e. a younger and hence
more inexpert child) the greater the acceleration and the greater the
whiplash effect affecting the vehicle and hence the driver of the vehicle.
Moreover the motor braking effect provided by the electronic control
system combined with the grip of the tyre according to the invention
favours the stoppage of the vehicle without causing a sensation of
discomfort for the driver which is implicit in known vehicles since the
stoppage occurs in a controlled, predictable and safe manner.
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Moreover the electronic control system allows control of the voltage
supplied by the battery to the motor during the starting movement and
reversing, preventing the motor being subject to uncontrolled electric
discharges (sparks between brushes and slip rings which cause motor
wear) and the battery having a shorter life owing to the consequent
stress.
Moreover, the electronic board fixes overload values of the motor (for
examples vehicles against an obstacle), protecting it from the stress
due to unnecessary operation during a standing start and wear of the
wheels which are forced to spin.
According to a preferred embodiment, the electronic control system
17 provides a closed-loop speed electronic control which, irrespective
of the payload, keeps constant a pre-established speed in any travel
condition such as on flat ground, during ascents or descents. According
to the present invention, a sensor defects the number of wheel turns
and conveys such a detected number of turns to the board. The board
compares a set speed with the detected speed and it supplies: a) more .
energy if the comparison results in a negative value (ascent); or b) less
energy if the comparison results in a positive value (descent).
in case the requested energy is less than zero, (the vehicle is driving
along a steep descent), the motor acts as energy generator and it
inverts the flow. This effect is used so that the motor is electronically
bypassed (see connection 19) and it acts as exhaust brake.
This results in a safer vehicle (exhaust brake during steep descents)
and in a more effective energy management (the power consumption
becomes strictly dependent on the type of travelled ground).
In order to regulate different speeds of the vehicle, an electronic-type
magnetic selector is provided, said selector being stepwise and it is
preferably regulated by a mechanical switch arrangement. The
mechanical switch arrangement is preferably provided on the gear lever
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(for toy car vehicles) or hand grip (for toy motorcycles or scooters) for
setting the gear. The speed is regulated through a magnetic sensor
which, once the position of the gear lever (or hand grip) has been
detected, communicates it to the electronic board. The electronic
system regulates the maximum speed set according to the gear
selected by the user.
Moreover, the electronic control system predefines (174) a maximum
limit of use of the battery in order to prevent complete discharging
thereof. .This.is not to the detriment of the vehicle's autonomy, since
the vehicle loses only an insignificant part of its autonomy in this
connection. As a result, since the battery cannot become completely
discharged, it may be fully recharged, something which otherwise would
not be possible, and the operating life of the battery is also increased
abaut three or four times compared to that which occurs in known
vehicles. The above does not increase the consumption of electric
power by the battery which, in the layout adopted according to the
present invention, is relatively low and allows a greater degree of
autonomy to be obtained compared that which is achieved with the
known layouts involving two motors.
Moreover, operation of the vehicle during recharging of the battery
may be disabled electronically as a result of the electronic control
system 17 (for example by means of simple introduction of a jack 181
of a battery charger 18) and not mechanically (as occurs in the known
vehicles), allowing the user to perform the necessary recharging
operations in absolute safety and very simply. On the other hand, in
the known vehicles, it was required to disconnect the terminals of the
battery in order to prevent a child attempting to use the vehicle during
recharging of the battery. The operation was laborious, awkward and
time-consuming also because it was required to remove the seat or the
saddle in order to gain access to the battery compartment.
