Field of Invention

[0001]
The present invention relates to an alarm device for use in solar powered vehicles and more particularly to a distress alarm, which warns the vehicle rider about presence of external agents such as dust or other factors, which inhibits solar power generation.

Description of Prior Art

[0002]
Depletion of non-renewable energy is fast catching up with our ever-growing energy needs. The impending crisis has shifted the focus of automobile makers to electric/hybrid vehicles. Electric vehicles are typically driven by charge stored in a battery, with the battery charged by an AC outlet plug in system. Hybrid vehicles are driven by a combination of a battery powered electric motor and a fuel burning internal combustion engine.

[0003]
Although an electric vehicle does not depend on burning fuels directly, they do use non-renewable sources like coal and other carbon based fuels for generation of electricity, which is used to charge the batteries. Solar energy is another conventionally used energy source for charging batteries in electric/hybrid vehicles. The development of unlimited, low cost and pollution free solar energy technologies will have multiple benefits in future when oil prices touch record high prices. A typical solar cell equipped vehicle for charging batteries, when parked in the sun, is much energy efficient than fixing the solar cells on stationary charging stations. Although the cost of installing the solar cells on a vehicle is substantial, its pay-back period is small, after which it literally comes free and without much maintenance. The constant charging of batteries using solar cells will increase the range of hybrid vehicles, for which they can go in electric mode, hence improving fuel economy. Further, solar cells can charge the battery of a hybrid vehicle in both of its running

[0004]
It has been observed that in case of excessive accumulation of
dust and soil on the solar panels, the rate of conversion of incident solar energy to electricity decreases several fold compared to normal working conditions, or in other words, the efficiency of the solar cells decreases. In case of vehicles, running on Indian roads, accumulation of dust is bound to happen. Dust or mud splashes also tend to come in contact with the solar panel surfaces, when other vehicles while running at high speeds on a rainy day pass the vehicle provided with solar panels. Efficiency of solar cells in vehicles may also be inhibited due to other factors, such as obscuration of the solar panel from sunlight, due to shadows caused when the vehicle is parked near a building or a tree. Therefore to optimize solar power generation in vehicles equipped with solar cells, it would be highly desirable to have a system that intimates the vehicle driver about presence of external agents such as dust or any other factor, which inhibits efficiency of solar power generation.

Summary of Invention

[0005]
The present invention has been conceived in view of the foregoing defects in the prior art and it is the primary objective of the present invention to provide an alarm device which alerts the vehicle driver about presence of any external agents or any other factors, which deteriorates solar power generation in a solar powered vehicle. The present invention comprises a solar power source generating a Vs, a plurality of comparators, alogic circuit, a switch and an indication means. The indication means warns the vehicle driver based on inputs from the switch. The switch is controlled by the logic circuit based on inputs from the plurality of comparators. The plurality of comparators compares the solar power source voltage Vs and voltage of a temperature sensor with certain preset reference voltages. The vehicle rider is intimated whenever solar power source voltage Vs falls below a certain threshold value in spite of favorable outside weather conditions.

[0006]
These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description, the appended claims and the accompanying drawings. This summary is not intended to limit the scope of the claimed subject matter.

Brief Description of Drawings

[0007]
The above and other features, aspects, and advantages of the present invention are further illustrated by the accompanying drawings. The drawings are given by way of illustration only and are not limitative of the present invention. A brief description of the drawings is as follows:
Fig. 1 is a side view of a conventional three-wheeled vehicle.
Fig. 2 is an isometric view of a conventional three-wheeled vehicle.
Fig. 3 is a block diagram of the present invention.

Detailed Description of Invention

[0008]
The present invention is hereinafter described with reference to the accompanying drawings. It is to be noted that like reference numerals designate corresponding or identical elements throughout the various drawings. The terms front and rear, and left and right as used indicate the front and rear and the left and right directions when viewed by a rider seated on a vehicle seat. For the sake of explanatory convenience, the present invention will be described as being embodied in a three-wheeled vehicle.

[0006]
Fig. 1 illustrates a side view of a conventional three-wheeled vehicle. A driver's cabin 13, which is open from both sides, enables the driver to enter and exit the vehicle. The driver's cabin 13 is provided with a driver's seat 15 and a handlebar 14. Control means for operation of clutch, gear, throttle etc. is provided on the handlebar 14. The vehicle has a front wheel 10 and two wheels 11 at the rear. The vehicle further has a passenger compartment 16 with a passenger seat 17. A power unit is generally mounted on a chassis 19 near the axis of the rear wheel 11. The power unit is provided with a lockable access door 18 on the vehicle.

[0007]
Fig. 2 is an isometric view of a conventional three-wheeled hybrid vehicle having thin film flexible solar cells 20 installed on its roof. The thin film solar cells are made on polymer substrate and are glued to the canvas roof of the vehicle. The thin film flexible solar cells 20 are configured to convert solar energy into electrical energy and generate a solar cell voltage Vs.
[0008] Fig. 3 is a block diagram of the present invention. As shown, the alarm device as per the present invention comprises a first comparator 10, second comparator 11, a logic circuit 12, a switch 13 and an indication means (not shown in the figure). The indication means is mounted to an instrument cluster of the solar powered vehicle and receives input from the switch 13. The logic circuit 12 receives input from the first comparator 10 and the second comparator 11. The switch 13 is controlled by the logic circuit 12 based on the above-mentioned inputs. Input from the first comparator 10 is the result of comparison of the solar cell voltage Vs with a first reference voltage Vm. Input from the second comparator 11 is the result of comparison of a temperature sensor output voltage VT with a second reference voltage VR2. The output voltage VT of the temperature sensor (not shown in the figure) is directly proportional to the outside temperature sensed by the temperature sensor. The first reference voltage VR1 is equal to 14V and the second reference voltage VR2 is equal to the output voltage of the temperature sensor corresponding to an outside temperature of 25° C. The logic circuit 12 can be a combination of logic gates or a micro controller.

[0009]
The logic circuit 12 controls the switch 13 based on the conditions given below in Table 1.
Table 1

The switch 13 is turned ON by the logic circuit 12, if as a result of comparison by the first comparator 10 and the second comparator 11, the solar cell voltage Vs is lesser than the first reference voltage Vm and the output voltage VT is greater than the second reference voltage VR2. The logic circuit 12 turns OFF the switch 13 in all other cases, i.e., when as a result of comparison by the first comparator 10 and the second comparator 11, the solar cell voltage Vs is lesser than the first reference voltage VRI and the output voltage VT is lesser than the second reference voltage VR2 or when solar cell voltage Vs is greater than the first reference voltage VR-I.

[0011]
Whenever the switch 13 is turned ON, the indication means on the instrument cluster of the vehicle is actuated thereby alerting the rider about lessened solar cell voltage in spite of the outside weather being favorable for solar power generation. The indication means can be either visual indication or audio indication or both. Thus the vehicle driver is warned whenever generation of solar cell voltage falls below a threshold (14V) even when outside temperature is greater than 25° C. As aforementioned, decreased solar power generation might be due to settlement of dust on the solar panel or due to other factors such as parking of the vehicle under shadow of a tree or a building. Hence the present invention enables to vehicle driver to avoid or remove factors inhibiting solar power generation. Therefore uninterrupted solar power generation is ensured.

[0012]
The foregoing description is a specific embodiment of the present invention and has been described for the purpose of illustration only. Persons skilled in the art may practice numerous alterations and modifications of the present invention without departing from its spirit and scope. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We Claim:

1. An alarm device for a solar powered vehicle, said alarm device
comprising:
a solar cell system configured to convert solar energy into electrical
energy and
generate a solar cell voltage Vs;
a temperature sensor which generates a output voltage VT, said output
voltage VT directly proportional to an outside temperature sensed by
the temperature sensor;
a logic circuit 12 which controls a switch 13 based on inputs from a first
comparator 10 and a second comparator 11;
wherein input from the first comparator 10 is the result of comparison between the solar cell voltage Vs and a first reference voltage Vm and input form the second comparator 11 is the result of comparison between the output voltage VT of the temperature sensor and a second reference voltage VR2.

2. The alarm device for a solar powered vehicle as claimed in claim 1,wherein the first reference voltage is equal to 14V and the second reference voltage is equal to the output voltage VT of the temperature sensor, said output voltage VT corresponding to an outside temperature of 25° C.

3. The alarm device for a solar powered vehicle as claimed in claim 1, said alarm device further comprising an indication means mounted to an instrument cluster of the solar powered vehicle, said indication means actuated when the switch is turned ON by the logic circuit.

4. The alarm device for a solar powered vehicle as claimed in claim 1, wherein the logic circuit 12 is a combination of logic gates.

5. A method of controlling an alarm device for a solar powered vehicle, said method comprising:

a) a first step of comparing a solar cell voltage Vs with a first reference voltage VRI ;
b) a second step of comparing an output voltage VT of a temperature sensor with a second reference voltage VR2;

c) a third step of turning ON a switch if, as a result of the comparison at step (a) and step (b), the solar cell voltage Vs is lesser than the first reference voltage VRI and the output voltage VT is greater than the second reference voltage VR2;

d) a fourth step of turning OFF the switch 13 if, as a result of the comparison at step (a) and step (b), the solar cell voltage Vs is lesser than the first reference voltage VRI and the output voltage VT is lesser than the second reference voltage VR2; and

e) a fourth step of turning OFF the switch 13 if, as a result of the comparison at step (a), the solar cell voltage Vs is greater than the first reference voltage VR1.

6. The method of controlling an alarm device for a solar powered vehicle as claimed in claim 5, wherein the first reference voltage is equal to 14V and the second reference voltage is equal to the output voltage VT of the temperature sensor, said output voltage VT corresponding to an outside temperature of 25° C.

7. The alarm device for a solar powered vehicle as herein above described in the specification and illustrated in the accompanying drawings.