NL9201544A - Control for electric model car - Google Patents

Abstract

The invention relates to a manual control for regulating the speed of different slot racing cars which are propelled by a high-speed electric motor powered from a small direct voltage (about 12 volts). These model cars move in a fixed course by means of a guiding slot, both sides of which have an electrically conductive strip. To limit the temperature dissipated in the manual control, the invention uses pulse-width power regulation. For this purpose, an approximately 400 Hz signal generator is incorporated in the manual control; the generated signal pulse width can be altered by the slider position whilst, in addition, settings for curve entry speed and brake power are provided and can be operated independently.

Description

Controller for electric model car.

The invention relates to a manual regulator for controlling the speed of an electric model car, which can drive in a predetermined course along a slot with an electrically conductive strip on either side, on which the supply voltage, which can be regulated via the squeezable slide of the manual regulator. in front of the car engine.

Such a manual controller is commercially available and consists of a handle with a mechanical contact device that slides over an openwork wire wound resistor. More or less resistance is introduced into the electrical circuit by means of this sliding. These known controllers operate with three connecting wires, which is customary in so-called "slot racing". One wire is the plus terminal to the power source, another wire is the terminal to the motor, and the third wire is called the brake wire. The positive connection is on the resistor, the motor wire is connected to the slide and the brake wire is connected to the negative terminal of the power supply and on one side of the "lock". If no speed is selected, the motor wire on the brake wire is shorted, so that the racing car is braked.

In the free classes, driving is done with motors that use more than 30 amps of current at a supply voltage of 13.8 volts under load. These engines can reach idle speeds of 250,000 revolutions per minute.

The standard classes, on the other hand, use significantly less power and therefore provide correspondingly less performance. For example, there are at least eight different classes in which this final racing sport is practiced. All these classes require their own ballast resistor controller and the resistance value of this also depends on the type of track being driven. This can be a fast circuit, but also a curvy relatively slow circuit. Also, the known regulator has no braking force setting, since the brake wire is connected or not. Nevertheless, this known regulator is frequently used because of its robustness and reliability.

There is an electronic controller commercially made in England, but this is a controller built in linear technology with separately connected box with two setting resistors for "resistance" and "braking force", in practice the quality turns out to be not too good and the controller burns out regularly.

The object of the invention is to provide a better product that can provide more performance, is durable and can be used for the different classes, so that the cost aspect when purchasing is significant.

The known regulator with control resistor has the main problem that the ballast resistor becomes too hot and in some cases even the housing becomes too hot and can no longer be held by the user. The mechanical resistance of the slider is also difficult, because it must be set so that it presses firmly on the control resistor and at the same time can well return to the zero position. The total driving current flows through the slide, which means that the slide is connected to the track by means of a thick wire.

The main problem of the English-made electronic controller is that it also gets too hot, but this happens in the remote hanging box and is therefore not immediately perceived as a nuisance, were it not that the box is regularly damaged by overheating. While driving, the driver's eyes are on his final race car, and the adjustment resistances of this English regulator are difficult to reach, because the box is mounted on the side of the track.

According to the present invention, the manual controller is characterized in that the manual controller accommodated in the handle is provided with three separate, manually operable stepless settings for the "curve", the starting speed and the braking force, respectively.

The curve setting serves to set the controller to the respective type of motor. Very heavy engines have a very steep power / rpm progression, that is to say the engine revs too fast for, for example, a winding course. By turning back the respective curve setting, the "driver" will feel more comfortable with the car.

Furthermore, according to the invention, the starting speed setting is adjustable between zero and about forty percent of the starting power at the beginning of the control curve. This setting determines the aggression of the car at the beginning of the control curve.

According to a further feature, the braking force setting determines the deceleration of the car by short-circuiting the motor in percentage.

According to a further elaboration of the inventive idea, a signal generator is accommodated in the handle of the manual controller with a pulse frequency of approximately 400 Hz, the pulse width of which is influenced by moving the slide in the handle. In order to prevent temperature dissipation in the controller itself, power control was chosen by means of this pulse width control. The total supply voltage is supplied to the "lock" at about four hundred times per second. The percentage ratio between "on" and "off" determines the total added energy. The switching frequency of the signal generator is selected at about 400 Hz for reasons of applicability to different types of motors.

According to a further elaboration of the invention, an output stage is arranged in the handle, with a plurality of power FET transistors connected in parallel with a maximum conductivity resistance of approximately 0.2 ohms. Due to the said parallel connection of the four transistors, the final resistance of the inverter becomes less than 0.05 ohms.

With this low resistance of the controller, the problem regarding the temperature in the controller itself is solved. If the current in the free classes increases to, for example, 30 amps, the total dissipated power within the regulator still does not exceed thirty times 0.05 is 1.5 watts. Since this power is distributed over a cooling plate integrated in the manual regulator, the temperature development here is virtually nil.

According to a further elaboration of the inventive idea, the manual controller is further provided with a brake stage accommodated in the handle with a power FET transistor, which, by pulse width control from the signal generator, short-circuits the electric motor of the car in time.

The invention will be explained in more detail with reference to the drawing.

Fig. 1 is a schematic view of a known manual controller for controlling the speed of an electric model car.

Fig. 2 is a manual regulator according to the invention.

Fig. 3 is the block diagram associated with FIG. 2.

Fig. 4, 5 and 6 give different settings of the motor power at different positions of the slide, with different settings for "curve", starting speed and braking power.

In Fig. 1, the numeral 1 schematically indicates the head of the known manual regulator, and numeral 2 the handle. A slider 3 is rotatably mounted within head 1, which finger can be operated by means of a trigger. A spring ensures that this slider is retracted to the zero position.

A wound resistor 4 is arranged inside the head 1, over which the free end of the slide slides. Numeral 5 indicates the end contact, which is connected to the black continuous conductor.

As can be seen from fig. I the power supply is a direct voltage of 11 to 13.8 volts, and the end contact 4a is connected to the red power wire, the end contact 5 to the black power wire and the slide near its pivot point is connected to the outgoing yellow wire to the slot controller.

Fig. 2 diagrammatically depicts a manual regulator according to the invention, the head now being indicated with the reference numeral 10, and the handle with the reference numeral 11. The slide has been omitted for the sake of clarity, but moves in the corresponding manner as with the controller according to fig. 1. The free end of the slide within the head 10 slides over a selection board, which will be explained in more detail yet.

On the outside of the head 10, three different rotary knobs 13, 14 and 15 are provided, which serve respectively for the curve setting, initial setting and braking force setting. Furthermore, an output stage 16 is arranged in the head, while a signal generator 17 and a braking stage 18 are arranged in the handle. The outgoing cord connections are omitted in Figure 2, but correspond to those in Figure 1.

For the sake of clarity, in Fig. 3 the block diagram from the illustration of the controller of Fig. 2 is shown again.

The signal generator supplies a supply voltage that is interrupted four hundred times per second. The percentage ratio between "on" and "off" determines the total transmitted energy. This switching frequency of 400 Hz has been chosen because of its applicability to different types of motors.

The speed of the electric car can be controlled by means of the slide, which slides along the block 12 schematically indicated in Fig. 3. Beforehand, the "driver" will have set the three different buttons 13 for the curve setting, 14 for the start setting and 15 for the brake setting.

The information about the selected speed and / or braking force is recorded by means of a mechanically almost the same construction as with the known regulator, but with the big difference that with the regulator according to the invention there is practically no current flowing through the slide, at least less than 1 mA. And no thick connection cable is needed anymore. The information flows through the return spring of the slide to the signal generator 17. The pressure with which the sliding contact of the slide is pressed against the setting board 12a (see fig. 2) is minimal compared to the known resistance regulator, but can possibly be be adjusted according to the user's feeling.

The low resistance of the controller solves the problem of temperature development. In the free classes of slot racing cars, if the current rises to, for example, 30 amps, the total dissipated power within the regulator according to the invention still does not exceed about 1.5 watts.

Fig. 4 shows three graphs of the motor power as a function of the slider position for three different curve settings, indicated by the position of the knob on the left side of the figure.

Fig. 5 shows a similar relationship between engine power and slider position at two different initial settings. It is clear that in the top graph the motor power is almost linear with the movement of the slider, while in the bottom graph a large part of the available motor power is immediately available.

It can be seen from Fig. 6 that other forms of motor power curves as a function of the sliding position can also be achieved by using two buttons simultaneously. The top curve of Fig. 6 shows a gradually increasing motor power to the break point where the motor power increases very sharply in the last phase of the sliding position.

In the middle image, with a slight displacement of the position of the slider, a lot of engine power is already available, which gradually increases up to the kink and then increases again.

In the lower curve of fig. 6, at the lowest slide position, a considerable amount of engine power is already present, which still increases up to the kink and can then increase even more.

It will be clear that any desired curve can be set. Every course and every type of electric motor can be set with the controller.

If during a race the tires of the car wear out, so the circumference becomes smaller, the "driver" can directly intervene by increasing the start speed by turning the relevant knob.

These possibilities and the fact that the regulator according to the invention is suitable for all engines and does not undergo heat development, makes it a unique product.

The four settings to be processed, curve setting, start setting, brake setting and slide setting, come together in the signal generator. The most important information, that of the slider, is divided into the selections "stop" and "drive". In the event that the information "stop" comes in, the control of the end stage is disabled and that of the brake stage is coupled with selected braking force setting. If "drive" is selected, the braking information is blocked and the output stage is controlled. Both the proportional brake and the driving pulse are obtained from the sawtooth generator. The frequencies of both controls are therefore identical. There are four power FET transistors in the output stage, because the electric motors use their maximum current when accelerating, which is many times higher than the energy generated when decelerating. Hence, only such a power FET transistor is required in the brake stage.

Claims (7)

1. Manual controller for controlling the speed of an electric model car that can drive in a set course along a slot with an electrically conductive strip on both sides on which the supply voltage for the car engine can be regulated via the squeezable slide of the manual controller. characterized in that the hand-held regulator is provided with three separate, manually operated stepless settings for the "curve", the starting speed and the braking force, respectively. Manual controller according to claim 1, characterized in that the curve setting serves to set the controller to the respective type of motor. Manual controller according to claim 1, characterized in that the initial speed setting is adjustable between 0 and about 40% of the starting power at the beginning of the control curve. Manual regulator according to claim 1, characterized in that the braking force setting determines the deceleration of the car by short-circuiting the motor in percentage. Manual controller according to one or more of the preceding claims, characterized in that a signal generator is accommodated in the handle with a pulse frequency of approximately 400 Hz, the pulse width of which is influenced by moving the slide in the handle. Hand controller according to claim 5, characterized in that an output stage is arranged in the handle, with a plurality of power FET transistors connected in parallel with a maximum conductive resistance of approximately 0.2 ohms. Hand controller according to claims 4, 5 and 6, characterized in that the brake handle also houses a brake stage, with a power FET transistor, which, by pulse width control from the signal generator, short-circuits the electric motor of the car in time .