GB2483728A - Self-propelled skateboard - Google Patents

Abstract

A skateboard that's self propelling uses a combination of bevel gears 1b and ratchets 1a to transmit drive to the road wheels. Preferably the skateboard uses two bicycle single speed ratchet (2 x shimano SF-MX30 single speed hubs) to drive the ground wheels with the use of gear cluster located on the lower deck of the skateboard. Optionally, permanent magnets may be used to adjust the stiffness of a truck 1h section of the skateboard. A swivelling footplate may be used to brake the road wheels.

Description

The &earhoard This invention relates to a new form of skateboard transport.

The skateboard improves the speed of the skateboard by using gears and ratchets combine to drive the road contact wheels. Its speed is easier to sustain than a bicycle and is also can be higher than a bicycle.

This makes it a viable road transport. Being only 88cm long, it is compact enough to carry into buildings. Its also hands free like an ordinary skateboard. The skateboard can achieve this high speed due to the double ratchet system and the high gear ratio, and because it uses four wheels, it is inherently stable and balance is not an issue.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig 1 show the Complete Gearboard Fig 2 shows how the front footplate drives the road wheel Fig 2.1 show how the rear footplate drives the road wheels fig 3.1 shows the exploded view of the bevel gear with the ratchets' integration Fig 3.2 Shows how the ratchet and bevel gear unit is screwed on to the centreplate Fig 4 shows the braking system Fig 4.1 shows an exploded view of the braking system.

Fig 5 Shows the steering maneuver Fig 6 shows the driving axle components for steering Fig 6.1 Shows the truck steering geometry in neutral position (no steering) Fig 6.2 Shows the truck steering geometry in 10 degree turning position Fig 7 Exploded view of the truck Fig 8 Shows the Magnetic suspension adjustment.

Fig 9 Shows the complete transmission gear ratios Fig 10 Lower deck exploded view Fig 10.1 Shows integration of the roller bearings into the lower deck.

Fig 11 show foot binding attachment to footplates According to the present invention, a torque is transmitted from the top deck to the road wheel via tower deck gears when the rider transfer his/her weight from one feet to another. This is done using two bicycle single speed ratchet (l.a shimano SF-MX3O single speed hubs) located inside two vertical bevel gears (1.b). The torque is the transmitted to the tower deck gear cluster (1.c). The Gear cluster magnify the speed and transmit drive to the front drive shaft (l.d) and the rear drive shaft (l.e). This then drives a swiveling transition gear (1.1). The angle of the transition gear allow the rider to turn the wheelshaft (1.g) and drive the road wheel at the same time.

The truck (1.h) has two functions I) Transmit drive to the road wheels 2) To steer the skateboard using "heel to toe" weight transfer Depending on the weight of the Rider the truck stiffness can be adjusted using the magnetic suspension (1.i). The suspension has neodymium-magnets located in the cavities that are repelling each other and their distances can be adjusted using m6. bolts located behind them.

The steering as well as the drive are controlled and generated by the two footplates, the front (1.j)and the rear (1.k). The rear footplate (1.k) has an additional control, which is the brake system.

Fig 2 to 11 will now describe in detail the complete anatomy of the Gearboard design.

Looking at propelling operation the Gearboard in fig 2. The rider transmit drive to the road wheels by transferring weight on to front footplate(l.j). This locks the the ratchet (1.a) and drives the vertical bevel gear (1.b). The vertical bevel gear drives the single helical gear (I.L) with at a higher speed. The single helical drives the twin helical gear (1.m) at the same speed. The twin helical drives the centrally located spur and bevel gear (1.n). The spur and bevel gear magnify the speed even further to the front drive shaft (1.d) and the rear drive shaft (l.e). The drive shaft transmits drive to the the transition gear (1.0 at the same speed. A final speed magnification is done from the transition gear (1.0 to the auxiliary gear (1.0). The Auxiliary gear then drives the wheel shaft gear (1.p) at the same speed.

The process of the rear footplate drive as illustrated in fig 2.1, shows the second ratchet locking and rotating the second vertical bevel gear. The second vertical bevel transmit drive in the same direction to the twin helical but rotates in the opposite direction to the sister vertical bevel gear (1.b in figure 1).

On fig 3.1, both vertical bevel gears are exploded to view how the single speed bicycle ratchets are integrated. The bicycle ratchets (1.a) are placed inside the vertical bevel gears (1.b) and are sandwiched between the ratchet support discs (3.a) and (3.b). The disc 3.b has an additional function in that it is a braking disc which the braking system pushes against to lock the both bevel gears from moving.

Both discs have m4 screw threads taps and, are screwed together using m4 bolts and completes the vertical bevel gear unit as shown in fig 3.2. In figure 3.2 the vertical bevel gear unit is screwed onto the bike hub screw thread (3.c), which is part of the centreptate (4.b as shown in fig 4).

A cioscr examination of the rear footplate braking is shown in fig 4.Turning the rear plate in either direction, and pushes brakeshaft (4.a) and its connecting section (4.a.2) which located in the centeplate (4.b). The brakeshaft then pushes 4 brake arcs (4.c) which rotates and pushes at right angles from the brake shaft. The brake arcs transmit the force to the brake shoe holder (4.c). This then pushes two brake shoes (4.e) which are 2 x shimano M70/T2 brake shoes on this prototype, against the vertical bevel gears(l.b). This stops the vertical bevel gears rotating and locks the gearing mechanism and consequently the road wheels.

With an exploded view of the braking system as shown in figure 4.1 a clearer understanding as to how the braking system can be obtained. The brake shaft (4.a) slides into the square cavity inside the centreplate and its connecting section (4.a.2) is screwed from the other end sticking out of the square cavity. The brakeshoe holder (4.d) slides into the brakeshoe support (4.g), white the brake arcs 4.c run along the top and bottom groves brake shoe support. The brake unit clamp (4.f) holds the brake arcs and brake shoe holder and is then screwed onto the centreplate using m6 bolts. The spring (4.h) located in the brake unit clamp pushes the brake shoe away from the vertical bevel gear when the brake released. It does this by pushing the brake shoe holder back into a filly recessed position into the brake shoe support (4.g). The last step of construction involves sliding the brake shoes (4.e) into the brake unit clamp (4.1) and glued into the brakeshoe holder (4.d).

Steering of the Gearboard is exactly the same as an ordinary skateboard. Fig 5 shows the rotation the front and rear axle of 10 degrees. These axle rotations are equivalent to the tilt angle of the gearboard and will be explained in detail in steering geometry diagram figure 6.1.

During steering the auxiliary gear (1.0), the wheelshaft (I.g) and its wheel shaft gear (1.p) orbits around the transition gear (1.1). Fig 6. illustrates the components that carry out the both steering and drive to the road wheels.

The steering geometry has three elements that determines its performance, these are illustrated in fig 6.1. These elements are 1) The angle between the driveshaft axis (6.a) and kingpin axis (6.b), this the steering angle (61).

this angle determines the ratio between steering and tilt angle of the gearboard. When the angle is 45 degrees as shown then the ratio is 1:1 2) The second element would be the angle between vertically intersectingaxis (6.e) (where the driveshaft axis (6.a) and the kingpin axis (6.b) meet through a vertical line) and the ground, this gives an angle (6.g). This determines the amount of tilt that the board is undergoing at any given instant. This in conjunction with steering angle (6.0 determines how much turn at any instant.

3) The orbit of the wheflixisJ6.d) illustrates the movement of the wheelshaft axis (6.c). This orbit occurs around the kingpin axis(6.b). If the steering angle (6.0 is smaller than 45 degrees then the gearboard tilt will be greater the steering, and if the angle is greater than 45 degrees then the board tilt (6.g)would be less than the wheelshaft angle (6.h), giving a more sensitive steering.

In figure 6.1, no steering is being undertaken, the vertical ground angle (6.g) is at 90 degrees meaning no tilt is applied to the board by the rider. The ratio between the wheel shaft angle(6.h) and the angle (6.g) is I I. This means that any change in the angle (6.g) gives an directly proportional change in the angle (6.h).

Figure 6.2 shows a gear board tilt of 10 degrees being applied. This increases the vertical ground angle (6.g) from 90 degrees to 100 degrees. Because the steering angle (6.h) is 1:1 with (6.g), then wheel shaft axis will rotate the equivalent 10 degrees. This is seen from the top view, where the angle (6.h) has proportionate reduction from 90 degrees to 80 degrees.

The "truck" is the sub component of the gearboard that holds the parts that are needed for steering and driving the road-wheels. It is the body or skin of the moving gçars and shafts that keeps it altogether.

Taking a closer look at the truck in fig 7, a detailed explanation of its construction will now be explained.

The truck top 7.a is the only component of the truck that secured to the gearboard main body. It transmit the steering action of the rider to the hanger main section (7.b) and the hanger second section (7.c). Both of these sections are joined together by a support shaft (7.e) and the wheel shaft (1.g).

The wheel shaft (1.g) slides inside the hanger main section and is held in place by the 15mm internal diameter roller bearing (7.f)(l60022z Metal Shielded Deep Groove Ball Bearing). The Bearing fits tightly in the hanger main section but is also secured horizontally by a main spacer (7.q), that slides over the wheel shaft. The same type of 160022z roller bearing is used as (7.j) on the kingpin (7.d), so that the transition gear (11) fits on it and rotates freely.

The hanger second section has two roller bearings (7.i) and (7.i.2)( both are 6000ZZ Budget Metal Shielded Deep Groove Ball Bearing lOx26x8mm) to hold the auxiliary gear (1.0) in place (7.x). In order to make sure that the bearing a secured horizontally a spacer (l.p) is placed in between the (7.i) and (7.i.2), that fit on to the auxiliary gear. Another roller bearing 6000ZZ roller bearing is placed inside the main cavity (7.s) where the wheel shaft (1.g) goes. The wheel shaft is connected by sifting inside the roller bearing (7.k) when the truck is fully constructed. Roller bearing (7.k) goes into back of inick top l.a and there to hold the drive shaft, it is the same 10mm roller bearing type as (7.i) and (7.i.2). A more complete understanding of (7.k) will be seen in fig 10.1.

Going back to the wheel shaft, once it is secured in the hanger main section with the main spacer (7.q), then the wheel shaft gear (1.p) slides on. The Wheel shaft gear is kept in place by the mini spacer (7.r).

Once the mini spacer is on the wheel shaft, then The support shaft (7.e) must slide through into the holes of the hanger main section support hole (7.v) . The support shaft stops the two hanger sections from rotating independently around the wheel shaft axis.The wheel shaft then slides into the hanger second section cavity (7.s) and the mini spacer provides an additional function of keeping the roller bearing (7.h) in place. The support shaft slides into the hanger second section support hole (7.u).

The wheel shaft will continue to go through the hanger second section hole (7.t) where a shaft slide stopper (7.o) is placed on it. This permanently position the shaft horizontally by wedging against the outside of the hanger second section once the wheel is screwed on.

The magnetic suspension comprises 4 permanent located above on the truck top (7.L) and 4 magnets in the hanger main section and hanger second second section (7.m). These determine the ride stiffness and will be discussed in greater detail in fig 8. They are adjusted using m6 bolts (7.n).

On Fig 8 an illustration of the magnets when secured in the truck is shown. When the rider travels at high speed skateboards tend to vibrate if the trucks are not tight enough. On an ordinary skateboard riders tighten their trucks normally by tightening the bolt on the kingpin, making it stiffer to turn the skateboard. On this magnetic design it easier to judge the suspension stifihess by looking at the position of the adjusting bolts (7.n) to determine how stiff the suspension is before riding. The magnets in the hanger section (7.m) are repelling against the magnets in the truck top (7.L). The repelling force increases when they are screwed closer together with the bolts (7.n) giving a tighter truck. There are number of magnet groups that can be used in this example there magnets are paired up that is, two magnets in each cavity, giving a total of 8 magnets. A combination 4,6 8 and even 12 magnets can be used, as well as different bolt lengths gives the magnetic suspension a much greater refinement of truck stiffness than a conventional truck.

In order to achieve a decent speed the gear board doesn't just rely on the double ratchets in the vertical bevel gears, but on a high gear ratio of 25:1 (on prototype 1). This is shown in figure 9. Figure 9 illustrates the gears only. The drive initiated from inside the vertical bevel gears where the bicycle ratchets sits as previously discussed. The bevel magnifies the speed to the twin helical and single helical gears with a ratio of 1:5. The ratio between the two helical gears is 1:1 since they are both transmitting drive to the spur and helical gear. The speed is reduced by half between the twin helical gear and the spur and bevel gear, which has a gear ratio of 1:2. At this point the gear ratio is I rotation of the vertical bevel equals 2.5 revolutions of the spur and bevel gear. Then the speed to the drive shaft is magnified by. the Spur and bevel with the ratio of 5:1. The gear ratio 1:1 remains the same between the drive shaft and the transition gear. Up until this point the vertical bevel gear has magnified the speed of the drive shaft to 12.5 times. The last speed magnification occurs between the transition gear and the auxiliary gear which is 1:2. This final doubling of speed gives a total gear ratio of 25:1 in the entire transmission. The final gear ratio between the auxiliary and wheel shaft gear is the 1:1. This gear ratio gives a 6% increase over a single speed bike with the same effort. Other gear ratio can be used, but the general rule is the higher gear ratio the higher the top speed, but the slower the acceleration.

Fig 10 shows basic construction of the lower deck and the connection of the trucks. The front connector (10.a) joins the truck top (7.a) to the left lower deck section (lO;b) and the right lower deck section (10.c). The Rear connection (10.d) connects the rear tuck top (7.a.2) to both the lower decks as well.

In order to reduce friction and wear in the skateboard, roller bearings are needed to hold the gears and drive shafts in the lower deck. These are shown in figure 10.1. The roller bearing (lO.1.a) is a 12mm internal diameter bearing that holds the top deck. This fits into the lower deck and allows the top deck to tilt to transmit drive to the helical gears. The bearing (10.1.b) is the same type of roller bearing but holds the helical gears in both sides of the lower deck sections. In this drawing, only lower left deck section (1O.b) is shown but the lower right deck is exactly the same as previously illustrated in figure 1O.The big bearing (10.1.c) has a 35mm internal diameter and is used to hold the main body of the centrally located spur and bevel gear. (10.1.d) rQller bearing also holds the spur and bevel gear but is for the smaller lower end of the gear component, it has a 15mm internal diameter. The drive shafts are supported by the two 10mm internal diameter roller bearings (10.1.e) and (10.1.0. The second bearing (10.1.fl is being held in place by the second drive shaft section (10.1.h) and by a lip inside the lower deck section. The roller bearing (7.k) previously mentioned in fig 7, is the final bearing that is placed on the very end of the drive shaft and connects inside the truck top.

In order for the rider to be more aggressive with the confidence to accelerate harder and to corner sharper as well as to brake later, feet bindings can be used as shown if figure 11. These are put on by switching the footplates upside down, where m6 fixing holes are located on the underside of the plates.

The footplates are then re-secured with the footplate locks 11.a.

Claims (4)

1. Claims 1) A Self propelling skateboard that uses at least I Bevel gear,(not spur or helical) to transmit drive from the center of the board to the end of the board where the road-wheels are located.
2. 2) A Self propelling skateboard, as mentioned in claim I, that has ratchet located inside the bevel gear to transmit torque in one direction.
3. 3) A Self propelling skateboard, as mentioned in claim 1, that uses permanent magnets to adjust the stifihess of the truck to reduce vibration at high speed.
4. 4) A Self propelling skateboard, as mentioned in claim 1, that uses a swiveling footplate to brake to brake the road wheels.