Introduction: How to Design and Make an E-GoKart 2000Watt
A go kart is a monoplace that allows us to feel vibrations and speed at ground level in the most fun way. For this reason, I can think of no better way than to build one for ourselves, to enjoy with ourselves, with friends, family or even with the little ones.
The versatility, easy and less maintenance that electric motors give us. The Choice of a brushless electric motor it’s due to the most efficient on the market as well as its high torque and power in such a small space.
There are several options to get make one. You can choose to buy a second-hand frame already and couple the missing components, motor, control unit ... or you can start from scratch, buy all the components separately, design and manufacture a custom frame and assemble all and each of the parts, as I show you in this Instructable. In this way, you will learn much more and it will be more fun!
And if you really liked it, don't forget to vote my project for the contest! ;-)
Step 1: Bill of Materials and Tools
Option 1: Four unities of Acid-Pb 12Volt / 36- 42Ah connected in series to get 48V: http://aclbaterias.es/inicio
Option 2: One pack of Ion Litio: LITIO_ION BATTERY 48V
5- Stainless steel pipes 30x30x1mm, frame
6- Kart seat
7- Stearing screw: Stearing screw
8- Plastic flanges, for fit electrical wires
11- Bearings support for D=30mm shaft
12- Bearing support for D=20mm pipe stearing
13- Break disc
1- MIG Welding
2- Circular saw
2- 3D Printer
3- Watt meter
4- Allen wrenches
5- Flat keys
Safety equipment as a kart pilot
3- Trainers o boots
4- Resistant clothes
Step 2: Parts and Components
Un kart se compone de las siguientes partes:
1- Frame: It is made up of a set of welded steel tubes, without bolting, forming a rigid structure. It will be important to do a regular check so that there are no fractures or holes that weaken the structure and can cause damage.
2- Seat: Normally made of fiber, it is an element against heat and possible, although unlikely, fire. Choose the right size for the pilot or a big thing so that most of them can carry it out.
3- Steering column: Includes the steering wheel, the steering bar, the rods and ball joints that transmit the turn.
The steering rods admit a length graduation thanks to their threaded ends and the limiting nuts. By varying its length, the convergence or divergence of the front wheels can be modified.
The convergence of each front wheel is defined as the angle between the plane of the wheel and the longitudinal axis of the kart. When they form an acute angle - the wheels close forward - there is a convergence. If the wheels are opened there is said to be divergence. Care must be taken to balance the setting for the various resulting rods of the same length.
4- Stems: The wheel stubs engage the frame mounts and the steering rods and the front wheels snap onto them.
5- Rear axle: It is the element of transmission of the kart and the only support of brakes in karts without changes. It is a solid or hollow steel bar, with a thickness that can range between 25 and 40 or 45 mm, depending on the chassis and category. It is screwed to the frame by means of two or three supports for the support points, with the bearings adjusted to achieve a good rotation of the shaft.
6- Brake: except in the karts with change, which have brakes on the front wheels, the brake disc is screwed to the disc carrier located on the rear axle.
7- Crown: Represents the transmission element from the engine to the rear axle. It must be aligned with the engine drive pinion for the chain to work accurately.
8- Chain: The chain must have the determined dimension according to the chosen crown. The voltage can be adjusted by moving the motor. An important element to consider is a chain guard to prevent breakage and / or accident or damage to the pilot.
9- Engine: The motor is the driving element of the Kart. The most efficient electric motor today, is a brushless motor. You can find from 500 W to 10.000 W, depending on how power you will required.
10- Wheels: It must be checked which child has the adapted dimensions and that there are no deformations. Pay attention to the wheel bearings, which are usually verses affected by dust or dirt.
11- Tires: Check their degree of wear, so that it is fixed in the depth of the grooves in the smooth tires or in the depth of the stripes in the depths.
12- Hubs: They are placed at the ends of the axles and are responsible for transmitting the torque from the axle to the wheels, normally through the necessary pressure is specified by the manufacturer on the sides of these . of a key.
13- Body: It is limited to a set of elements consisting of the side pontoons and the front pontoon. These can be given aerodynamic shapes and stickers can be added, giving the kart a personal touch.
14- Screw and nuts: It is what unites the different elements of the chassis. You have to pay special attention to them due to the vibrations that the kart experiences.
Step 3: Frame. Design and Construction
The frame is made up of a set of welded steel tubes, not screwed, forming a rigid structure. One of the most important points that determines the behavior of the kart is the distribution of the weight in the chassis.
There is no fixed rule for the ideal distribution, but modifying the center of gravity will change the transfer behavior weight when cornering or braking.
Depending on the arrangement of the motor and the batteries, you can play with the position of the seat to adjust the weight distribution. As well as the height of the seat, the lower we have it, the greater stability we will achieve, instead the more we raise the center of gravity the better lateral weight transfers.
The lack of shock absorbers establish greater importance on the rigidity of the frame . Thus, less rigidity corresponds to greater flexing capacity and therefore less possibility of sliding, more grip.
In our case, we have designed the central part with round tubes of greater section (D = 30mm e = 2.5mm) to transmit the maximum power to the ground and the periphery with AISI 304 square profile smaller section (30x30x1mm) to gain more flex. The choice to do it with miter cut and welded tubes has been the lack of a tube bender. (See plan and photo)
Note: In order to weld with an inverter, it is necessary to have a stainless steel electrode arrangement as long as the AISI denominated steel tube is chosen. And above all, for inexperienced or beginning welders, be careful when welding, since if the tube is thin-walled, it can cause holes.
Step 4: Stearing
The steering system consists of the set of elements that allow the kart to trace the path set by the driver. It includes the steering wheel, the steering bar, the links that go to the front knuckles, through the corresponding ball joints.
- Steering wheel: In this case we have designed the steering wheel from 0..
It consists of a central stainless steel sheet, two handles at the ends, fastened by three screws each to the central sheet. The central plate that is attached to the pineapple through 4 screws and the pineapple, which is responsible for attaching the steering wheel to the steering bar through a screw that goes through the bar. The handles and steering boss are made by 3D printer, ABS material. (See Photos and assembly drawing). I will attach the plans and parts at the end of the Instructable.
If, on the other hand, you prefer to buy a steering wheel already made and finished, I leave you an option: Steering wheel
- Steering bar: In this case it does not have a kneecap.
It is made up of a 20 mm diameter hollow tube, with a screw welded at one end (lower support point), a hole pierced at the other end coinciding with the pineapple joint and a plate located at 50 mm from the bottom where the connecting rods will be joined through the ball joints. This bar is held between the screw on the lower end and a support on a bearing support just below the flywheel, to withstand the forces generated by turning
- Stems: they connect the steering bar with the spindles.
They are formed by a 10 mm diameter tube for each side. An approximate length of 160 mm. And a welded nut (M6) at each end to allow adjustment along with the ball joints. In this way we will be able to adjust the divergence or convergence of the direction.(see photo) . Or you can buy it already made: Steering stem
- Stub Axles: They are attached to the frame supports and they are attached to the tie rods through another ball joint. It is composed of three welded parts.
In this case, we have designed the wheel axle (see drawing), to fix the wheel by means of a KM nut and safe washer. The hub perpendicular to the axis that contains the bearings has been designed and allows rotation with respect to the frame, (see drawing). And finally, the joint plate, specifically designed to generate the Ackerman triangle, between the two front axles and the center of the rear.
In case you want to buy it, I leave you an option:
Step 5: Rear Wheels and Shaft
It is the element of the kart transmission where the driving wheels and the sole brake support are placed.
It is a hollow or solid steel bar, with a diameter that can range between 30 and 45 mm (see plane).
This bar is adjusted to the chassis by means of two or three supports for the support points, with the appropriate bearings to achieve a good rotation of the axis. Bearing support D=30mm
So, on the rear axle we will incorporate three elements: the crown, the brake disc and the rear wheel hubs, one at each end. All of them rotate jointly to the shaft, therefore, they need a power torque transmission system, between the element and the shaft. In this case (see drawing), the solid shaft has been milled to place a key for each element.
The keys way used have a section of 6x6 mm. key ways
Note: It is important that the keys fit as closely as possible, so that they cannot escape or have any apparent play.
The chosen crown will depend on the transmission ratio that we calculate , depending on whether we want more speed or more strength. I explain this in step 7.
The brake disc is placed in the same way as the crown, but on the opposite side. To attach them to the axle, we need specific supports for each disc, such as the following: Brake Carrier
As a brake caliper and drive pump, we can use one of an old motorcycle and attach it by means of a support. Or look at a cheap one online.
Finally, name the hubs where we will fix the wheels to the axle. We will only have to fit the key, adjust and fix them one at each end of the bar.
The most important points for mounting are:
- The axis must be perfectly straight, in a single line and without any twist at any point.
- It must be centered in the frame, without being heeled to any side.
- It must be parallel to the chassis so that the different points on it are placed at the same distance from the ground.
- It has to rotate easily on its bearings.
Step 6: Electric Motor and Controller Conexions
The motor is the driving element of the Kart. We could get a gasoline engine like the ones of a lifetime. But in our case, we are going to connect an electric one for simplicity, less volume, and less maintenance. Not to say that it does not pollute, it makes less noise and is cleaner.
The chosen motor is brushless, also called in English brushless motor, of 2000 Watt.
Today we can find many models at a very competitive price. They all require a switchboard, which allows us to control and limit the power delivered, as well as the possibility of connecting the throttle, ignition, lights, reverse gear ...
I have connected in series a consumption or power meter, to be able to do my measurements, look at consumption, and check the batteries on the screen at all times. Power meter
Note: It is very important to look at the battery manufacturer's specifications so as not to exceed the minimum when discharging them.
In my case, the batteries that I have selected are 12V 42 Ah, http://aclbaterias.es/inicio
I have chosen Acid Pb, which implies that they weigh much more than those of Lithium, but they are also cheaper. With 42 Ah, it gives me quietly to spend almost an hour taking the kart with the pedal fully.
The motor requires a voltage of 48V, therefore I have needed 4 batteries connected in series (as I show in the photo). For this, it is important to use cables with a section of not less than 6mm, so that the losses are as little as possible, as well as preventing the cable from heating up.
Note: As a prevention, I have put a 50Ah fuse, so that at a possible peak, the electronics and the motor will protect me. It is not really necessary, since the Driver already has its integrated protection.
Step 7: TRansmision
As chain drive is carried out, each tooth on the sprocket forces one link to travel and "pulls" on another crown tooth. As the crown is larger than the pinion, several engine revolutions are necessary for the wheels to rotate one revolution. It is the gear ratio.
As in any other vehicle, from cars to bicycles, the "shorter" a gear is, the more gear ratio there is (first or second speed), the more available greater acceleration capacity, better traction but lower top speed. The longer -smaller gear ratio- (fourth or fifth) better top speed and worse acceleration.
To calculate the gear ratio or development you must count the teeth of the pinion and the crown and perform the following calculation:
Crown Teeth / Pinion Teeth
The chain is the connecting element between the pinion, located on the motor, and the crown, on the rear axle. The chain must be the appropriate length according to the size of the crown chosen since there is no tensioning element, which forces to have chains of different sizes or reform them by adding or removing links. The chain tension is adjusted by displacing the motor. For this reason, the motor support base must have some type of guide, to be able to move it there, allowing the chain to be tensioned
Step 8: Testing and Recomendations
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... and give me your vote!
Here are some references from web's to consult more detailed information on design, plans and technical explanations as well as other projects that can help you.
And of course Any questions you have I will be happy to answer the comments. Greetings!
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