GB2084096A - Electric car systems - Google Patents

Abstract

The supply system comprises spaced conductors 3 mounted on and insulated from the road and connected to a source of electrical power. Each car has a plurality of collecting shoes 5 which pick up power from the conductors. The maximum width of each shoe is less than the minimum spacing of the conductors. <IMAGE>

Description

SPECIFICATION Improvements in or relating to electric car systems The present invention relates to electric car systems. The term car as used herein is intended to include within its meaning all types of powered vehicles which used the roads.

According to one aspect of the invention, there is provided an electric car system comprising a supply system including a plurality of spaced elongate conductors mounted on and insulated from the ground, and electrical power supply means connected to the conductors; and at least one electrically driven car, the or each car being provided with a plurality of collecting shoes arranged to contact the ground so as to pick up power from the conductors, the maximum width of each shoe being less than the minimum spacing between conductors.

According to another aspect of the invention, there is provided a supply system for use in an electric car system according to the invention.

According to a further aspect of the invention, there is provided an electric car for use in an electric car system according to the invention.

It is thus unnecessary to provide overhead power cables on rails, and the cars may be driven essentially like a conventional car.

Such an electric car may contain a battery as a reserve source of power affording the car a predetermined driving range, the battery being recharged when the car receives current from the supply system. Thus the car is not wholly restricted to use on roads provided with such a supply system.

The car may contain a meter so that the owner pays to the supplier of electricity an amount according to the meter indication.

Such an electric car system could dispence with roadside petrol stations and with the inconvenience of having to refuel. Further, as the system runs on electricity which may be generated in any convenient way, it would be possible to reduce greatly or even eliminate pollution. Such a system should also be efficient in its use of energy.

Conventional cars could be converted for use in such a system with a substantial saving in weight, perhaps by up to two thirds, resulting from replacing a conventional internal combustion engine by an electric motor. Further, the waste in resources, in particular petrol, which results from idling of an internal combustion engine when at rest in traffic can be eliminated.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure lisa plan view of conductors mounted on a road surface; Figure 2 shows a cross section taken on lines 1-1 of Figure 1; Figure 3 is a side view of a car illustrating the insulation of collecting shoes therebeneath; Figures 4, 5, and 6 illustrate in plan thus possible elative positions of a car provided with collecting shoes and conductors on a road surface; Figure 7 is a side view showing the arrangement of the collecting shoes in more detail; Figure 8 is a front view corresponding to Figure 7; Figure 9 is a circuit diagram of a rectifier arrangement installed in a car; Figure 70 is a circuit diagram of a control arrangement for a car;; Figure 11 illustrates in more detail part of the circuit shown in Figure 10; Figure 12 illustrates an alternative form of collector shoe diagrammatically in plan; Figure 13 is a side view of one of the collector shoes shown in Figure 12; Figure 14 and 15 show front and side views, respectively, of another type of collecting shoe; Figure 16 illustrates in plan another arrangement of road-mounted conductors and electric cars for use thereon; and Figure 17 is a circuit diagram of another rectifier arrangement for use in the electric car shown in Figure 16.

As shown in Figure 1, two parallel insulative bands 2 are placed on a road surface 1. A conductor 3 is mounted on the top of each of the bands 2 at its middle so as to stand proud of the road surface by, for instance, about 10 millimetres. Such an arrangement of the conductors 3 thus has no substantial effect on traffic using the road. As illustrated in Figures 1 and 2 transverse openings 4formed in the insulative bands 2 permit drainage of water from the road surface, for instance caused by rain, so as to prevent the occurrence of short circuits from the conductors 3 to ground.

The distance between the pair of conductors 3 may be selected according to various requirements.

However, a distance of approximately 150 millimetres would see to be preferable. The conductors 3 are supplied with electricity at a potential of, for instance 60 volts. In any event, the potential of each of the conductors 3 should be sufficiently low to avoid the risk of damage or injury through electric shock. The insulative bands 2 insulate the conductors 3 from the road surface and serve for spacing the conductors, while also fulfilling a sound-proofing or cushioning function.

The conductors 3 are divided along their length into sections which are insulated from each other but can be connected together. Each of the sections, or alternatively only some of the sections distrubuted along the length of the conductors 3, is connected to an electrical supply and distrubution station. These stations perform automatic safety switching functions permitting power to various sections to be cut off for the purpose of safety when a short circuit or leakage of current to ground occurs.

For instance, if water accumulates above the height of the insulative bands in one or more of the sections, then the power to those sections can be cut off to prevent danger.

Figure 3 illustrates a pair of groups of current collecting shoes 5 disposed below the body of an electrically driven car. As illustrated in plan in Figures 4to 6, each group comprises a plurality of collecting shoes disposed in a line transversely of the car, with one group being disposed near to but spaced apart from the other group in the longitud inal direction of the car transverse to the lines of collecting shoes. The collecting shoes 5 extend substantially across the whole width of the car body.

Figure 4 illustrates the relative positions of the collecting shoes and the conductors 3 mounted on the road surface when the car is driven along the road with the conductors 3 extending longitudinally and substantially centrally of the car body.

Figure 5 illustrates the relative positions of the collecting shoes 5 and the conductors 3 when the car is driven substantially along the right hand side of the conductors 3, whereas Figure 6 illustrates the relative positions when the car is driven along the lefthand side of the conductors 3, it being assumed that forward motion of the car is in a direction generally upwardly in these Figures. Thus, the collecting shoes 5 remain in contact with the conductors 3 provided the car is driven at or within the extreme positions shown in Figures 5 and 6, thus allowing the transverse position of the car on the roadway to vary u pto approximately twice the body width of the car without the collecting shoes 5 breaking contact with the conductors 3.Further, the length of each collecting shoe 5 is close to but less than the spacing between the conductors 3 so as to prevent a short circuit forming between these conductors. Also, the distance between each adjacent pair of collecting shoes 5 of each group is less than the spacing between the conductors 3 and adjacent shoes in thetwo groups overlap laterally of the car so that at least two collecting shoes 5 will always be in contact with respective conductors 3 provided the car remains at or within the extreme positions with respect to the conductors 3 illustrated in Figures 5 and 6. It is therefore completely unnecessary for any guide means such as rails to be provided for the car, which may be constituted by any form of automobile such as a private car.

Figures 7 and 8 illustrate in more detail the arrangement of the two groups of collecting shoes 5 mounted below a car. In particular, the two groups of shoes 5 are pivoted about pins 6 which are fixed to the body of the car. Accordingly, the collecting shoes can swing about horizontal axes transverse to the car body. The two groups of collecting shoes are further mechanically interconnected by pivotally mounted connecting bars 7 and 8, the connecting bar 7 being mechanically connected to a motor 27 (Figure 10) for retracting or lowering the collecting shoes 5. Thus, when the electric car is being driven over a road surface not provided with conductors 3, the motor can be operated to retract all of the collecting shoes 5 so that they no longer contact the ground and thus do not disturb nomal running ofthe car.

Figure 9 is a circuit diagram showing the connection of the collecting shoes 5 to a rectifier arrangement 13 for providing electrical power of constant polarity to the remainder of the circuit of the electric car. Thus, each of the collecting shoes 5 is connected to the anode of a rectifier 11 and the cathode of a rectifier 12. The cathodes of all the rectifiers 11 are connected together and to a positive supply line 9, whereas the anode of all the rectifiers 12 are connected together and to a negative supply line 10.

Thus, no matter which collector shoe 5 contactes which'polarity of conductor 3, the rectifier arrangement 13 ensures that the positive supply line 9 is always positive with respect to the negative supply line 10. For instance, if the collecting shoe 5-1 is in contact with the positive conductor 3 and the collecting shoe 5- 2 is in contact with the negative conductor 3, the rectifiers 11 - 1 and 11 - 2 are effectively connected in series between the conductors but back-to-back so that the two conductors are isolated. Current will therefore flow from the collector ing shoe 5 - 1 through the rectifier 11 - 1 and via the positive supply lead 11 to the remainder of the electric car circuitry. The return current will flow through the negative supply line 10 and through the rectifier 12 - 2 to the collecting shoe 5 - 2.If the polarities of the collecting shoes 5 - 1 and 5 - 2 are reversed, then the rectifiers 11 - 1 and 12 - 2 will be reversed biased and will cease to conduct whereas the rectifiers 11 - 2 and 12 - 1 will conduct so that the positive supply line 9 remains positive with respect to the negative supply line 10.

Figure 10 is a circuit diagram of the electric car including the rectifier arrangement 13 shown diagrammatically. The car is provided with an infra-red emitter 43 controlled by a circuit 41 and mounted in a housing 42 having a suitable aperture or the like so as to direct infra-red radiation towards the road surface. The housing 42 is angled so that the radiation is reflected from the road surface towards another housing 45 having an aperture behind which is mounted in infra-red receiver 46 connected to means 44 for operating a switch 26 which controls the supply of power to the motor 27 for lowering or retracting the collector shoes 5.Sensitivity of the arrangement 44 is such that the switch 26 is closed only when the reflected infra-red radiation received by the receiver 46 is greater than a predetermined amount, such that the radiation is being reflected from the conductors 3 rather than from the road surface, which has a lower reflectivity to infra-red radiation.

Circuit block 30 shown in Figure 10 is illustrated in more detail in Figure 11. This arrangement comprises a transistor whose collector is connected to the coil of a relay and whose base is connected to a potential divider across the supply lines 9 and 10.

Thus, when the voltage across the supply lines 9 and 10 is less than a predetermined value, the transistor remains cut off so that the relay does not operate.

Under these circumstances, the relay contact 14 is in position b and the relay contact 33 is open. When the voltage across the supply lines 9 and 10 is greater than a predetermined level, the transistor is turned- on sufficiently for the relay to be energized so that the relay contact 14 is in position a and the contact 33 is closed. It is thus possible for the electric car ta run over different road surfaces having conductors supplied at different potentials. For instance, the voltage across the conductors 3 on an oridinary road or highway may be less than that on a motorway or freeway.

The terminals a and b of the relay and the negative supply line 10 are connected to inputterminals 15, 16 and 17 respectively, of a Watt Meter or power consumption meter for measuring the amount of electricity used by the car. The input terminals 15, 16 and 17 are connected through the meter 18 to lines 21, 20 and 19 respectively, which supply the remainder of the car circuit. The line 19 is connected directly to one terminal of a drive motor 24 of the electric car which is provided with windings having two other terminals according to the two different voltages expected to be received from the conductors 3.

These two other terminals are connected via lines 28 and 29 and through a pedal operated switch 22 or the like to the lines 21 and 20 so that depression of the pedal 22 causes electric power at the correct potential to be supplied to the appropriate terminal of the motor 24.

A voltage stabilizer 23 is provided between a storage cell or battery, such as an accumulator, and the meter 18 so that, no matter what voltage is received by the circuit arrangement, an appropriate voltage is supplied to the battery 25 so as to charge it up to its maximum capacity. Accordingly, the battery 25 is charged up to its maximum capacity whenever electrical power is received from conductors 3 on the road surface. An isolation diode 34 is connected between the line 20 and the regulator 23 with its cathode connected to the regulator 23. However, when the contact 33 of the relay is closed, the cathode of the diode 34 is shorted to the line 21.

Accordingly, when a relatively high voltage is received by the collector shoes 5, the contact 33 is closed and the diode 34 is reverse-biased. The lines 21 and 20 are thus isolated electrically from each other. This diode further prevents the battery 25 from being charged at an excessive or dangerous rate resulting from excessive voltage supply from the conductors 3, the charging rate being determined by the stabilizing effect of the voltage stabilizer 23.

When the car is running over a road surface not provided with conductors 3, power to the motor 24 is supplied by the battery 25. Power is supplied via the isolating diode 32 and via a lamp 31 which lights to indicate that current is being supplied from the battery 25. Under these circumstances, the switch 26 is operated and the motor 27, which may be a conventional windscreen wiper motor, retracts the collecting shoes 5 from the road surface in orderto protect the shoes against wear by the road surface and so as to avoid disturbing normal running of the car on the road.

The embodiment described hereinbefore relates especially to electric cars for long distance driving.

An alternative embodiment, as hereinafter described, may be provided for an electric car capable of turning while maintaining contact with conductors mounted on the road surface.

Figures 12 and 13 illustrate an arrangement in which a road surface is provided with conductors 34 mounted on insulative bands 35 for the supply of electric power to a car. The car is provided on its underside with five collecting shoes 36 arranged at the corners and centerof a square. Each collecting shoe is mounted on an arm urged by a spring 37 toward the road surface so as to maintain contact between the collecting shoe 36 and the surface or conductor 34. As shown in Figure 12, the distance between adjacent collecting shoes 36 is less than the width between conductors 34 so that, for any orientation of the car, at least two conductors will be contacted and at least one collecting shoe will contact the positive conductor while at least another one collecting shoe will contact the negative conductorso that supply of power to the electric car is always maintained.Thus, the orientation of the car may vary about 360 degrees without supply of power from the conductors 34 to the collecting shoes 36 being interrupted. Any number of conductors 34 may be provided across the road surface.

Thus, this embodiment differs from that illustrated in Figure 4 to 6, wherein contact is only maintained when the car is driven generally along the conductors 3.

Figures 14 to 16 illustrate another arrangement of collecting shoes 38 which consist essentially of circular plates or wheels urged by a spring into contact with the road surface and capable of running therealong. The collecting shoes are also arranged at the corners and in the center of a square. However, in this embodiment, the conductors 39 are of much greater width than the width of the exposed insulative bands 40. However, this arrangement has similar features to that of the arrangement shown in Figures 12 and 13. Thus, the maximum width of the collector shoes 38 is still less than the width of the insulative bands, and the electric car can move and turn optionally without interruption in the supply of electric power thereto.

Figure 17 shows the circuit diagram of a rectifier arrangement having five input terminals to which the collecting shoes of the arrangement shown in Figures 12 and 13 or in Figures 14to 16 may be connected so as to provide two supply rails of constant polarity. This rectifier arrangementfunc- tions in exactly the same way as that shown in Figure 9.

Claims (19)

1. An electric car system comprising : a supply system including a plurality of spaced elongate conductors mounted on and insulated from the ground, and electrical power supply means connected to the conductors; and at least one electrically driven car, the or each car being provided with a plurality of collecting shoes arranged to contact the ground so as to pick up power from the conductors, the maximum width of each shoe being less than the minimum spacing between conductors.

2. A system as claimed in Claim 1, in which the conductors are divided along their length into sections connected to respective distribution stations for permitting sections to be electrically isolated.

3. A system as claimed in Claim 1 or 2, in which each conductor is mounted on an insulative band mounted on a road surface.

4. A system as claimed in any one of the preceding claims, in which the collecting shoes are arranged in two rows disposed transversely of the car and spaced apart longitudinally, the length of each shoe being less than the minimum spacing between the conductors, the spacing between adjacent shoes in each row being less than the minimum spacing between the conductors, and the ends of the shoes in the two rows overlapping each other.

5. A system as claimed in any one of the preceding claims, in which the collecting shoes are pivotally mounted to the car and connected via a linkage to a motor to allow the shoes to be retracted.

6. A system as claimed in Claim 5, in which the motor is arranged to be controlled by an infrared sensor cooperating with an infrared emitter located below the car so as to receive infrared radiation reflected from the ground or conductors.

7. A system as claimed in any one of Claims 1 to 3, in which the or each car has five collecting shoes disposed at the corners and centre of a square, the conductors being arranged as alternate positive and negative conductors.

8. A system as claimed in Claim 7, in which the spacing between the centres of shoes on each side of the square is larger than the spacing between conductors.

9. A system as claimed in any one of the preceding claims, in which the or each car has a storage battery for powerig the car when current from the conductors is interrupted, the battery being arranged to be charged when current is supplied from the conductors.

10. An electric car system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

11. A supply system for use in a system as claimed in any one of the preceding claims.

12. An electric car for use in a system as claimed in any one of the preceding claims.

13. An electric car system which is characterized by the using of a pair or more of conductive wires on ground, each wire is placed on an insulative band in order to keep wire to be insulated from each other, distribution substations are installed along the wires at appropriate distance in order to control power transmission in every section so that power in a section can be cut off in case of breakdown, leakage or short circuit.

14. An electric car system which is characterized by using of a plurality of collecting shoes beneath a car, the collecting shoes are divided into two rows or more and the length of each collecting shoe is less than the distance between every two conductive wires; in power collecting process, at least a collecting shoe in a row should contact with another conductive wire in order to maintain a constant power supply.

15. An electric car system wherein there are two or more conductive wires which carry positive and negative current respectively in alternate arrange ment and all conductive wires are insulated from each other; five collecting shoes are equipped beneath an electric car and the maximum width of each collecting shoe which contacts the travel surface is less than the width of insulative band so that a collecting shoe can only contact with a conductive wire.

16. Collecting shoe as defined in Claim 13 Claim 14, wherein connecting bar is installed between two adjacent collecting shoes and driven by a motor so that when the electric car is apart from the conductive wires, the collecting shoes can be pulled up and free from contacting ground.

17. An electric car system as defined in Claim 13 and Claim 14, wherein the battery of the electric car can be charged while the car is running on conductive wires so that power is available when the car is away from conductive wires.

18. An electric car system as defined in Claim 15, wherein the five collecting shoes are in square arrangement with a shoe at the middle, center to center distance between two shoes at a side the square arrangement should be largerthan the width of an insulative band where conductive wire is placed, so that at least two collecting shoes will contact with two conductive wires of different polarity while the car is running so that a normal power can be supplied without any interruption and the car can move and turn optionally.

19. An electric car system as defined in Claim 13 and 14, wherein the collecting shoe contacts with conductive wire by means of the control of Infra-red launch, receiver and receiving assistant instrument.