WO2022097214A1 - A stable scootor - Google Patents

A stable scootor Download PDF

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Publication number
WO2022097214A1
WO2022097214A1 PCT/JP2020/041278 JP2020041278W WO2022097214A1 WO 2022097214 A1 WO2022097214 A1 WO 2022097214A1 JP 2020041278 W JP2020041278 W JP 2020041278W WO 2022097214 A1 WO2022097214 A1 WO 2022097214A1
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WO
WIPO (PCT)
Prior art keywords
steering
scooter
steering shaft
front wheel
ground
Prior art date
Application number
PCT/JP2020/041278
Other languages
French (fr)
Inventor
Yves Potin
Antoine Ducloux
Matthieu PELISSE
Arnaud Frappart
Original Assignee
Compagnie Generale Des Etablissements Michelin
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Compagnie Generale Des Etablissements Michelin filed Critical Compagnie Generale Des Etablissements Michelin
Priority to PCT/JP2020/041278 priority Critical patent/WO2022097214A1/en
Publication of WO2022097214A1 publication Critical patent/WO2022097214A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K3/00—Bicycles
    • B62K3/002—Bicycles without a seat, i.e. the rider operating the vehicle in a standing position, e.g. non-motorized scooters; non-motorized scooters with skis or runners
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K19/00—Cycle frames
    • B62K19/30—Frame parts shaped to receive other cycle parts or accessories
    • B62K19/32—Steering heads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
    • B62K21/00—Steering devices
    • B62K21/18—Connections between forks and handlebars or handlebar stems

Definitions

  • the present invention relates to a scooter and in particular a scooter providing improvement on its stability.
  • a scooter, a kickboard or alike, assisted electrically, by engine or not, is an increasingly used as a means of urban transportation, that has a good efficiency of payload per vehicle mass.
  • the scooter’s characteristics such as light and very compact when folded makes it possible to carry under the arm during public transportation or to be placed in an office, eliminating a need for a garage space while allowing to travel in a city traffic at around 25 km/h.
  • EP1240073 discloses a scooter having a fork which is rearwardly angled with respect to a fork rod for positioning handlebars at a great height making it possible to tilt a steering column with little physical force.
  • DE102012204915 discloses a scooter having a steering system for easily and safely steer with just one hand while eliminating several disadvantages such as rapid fatigue, uncomfortable to wear.
  • a “caster angle” is a tilt angle of a steering pivot axis compared to an imaginary vertical line as viewed from the side. When the steering pivot axis slants forwardly, it is called as a “negative caster angle”.
  • An “offset”, also called as a “caster trail” is a distance from the intersection of the steering pivot axis with ground to the center of the wheel-to-ground contact area.
  • a “wheel assembly” is an assembly of a rotating object intended to contact with ground and rotating around an axis of rotation.
  • the wheel assembly may be a quasi-rigid or elastic wheel sole, a wheel enveloped on its outer circumference by rubber or plastic-like material, a wheel with a tire, pneumatic or not, mounted onto the wheel.
  • the present invention provides a scooter comprising a main body configured to support a rider, a rear wheel assembly rotatingly coupled to the main body around a rear wheel axis, a steering assembly that includes an upper steering shaft rotationally coupled to the main body through an upper steering support, a lower steering shaft rotationally coupled to the main body through a lower steering support about a steering pivot axis SPA, the lower steering shaft being configured as to have a negative caster angle A, a steering joint connecting the upper steering shaft and the lower steering shaft, a front wheel assembly rotatingly coupled to a front wheel support about a front wheel axis, the front wheel support being pivotally coupled to the lower steering shaft, the front wheel support being configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly with ground G, the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly with ground G.
  • This arrangement provides an improvement on stability of the direction of the scooter.
  • the front wheel support being configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly with ground G, and the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly with ground G, the front wheel assembly produces a self-aligning torque, a torque tends to steer the wheel toward the direction in which the scooter is traveling, in particular at higher speed range, e.g. above 15 km/h. Therefore, it is possible to improve stability of direction of the scooter in particular in straight line and at higher speed range.
  • the self-aligning torque produced would also act as to prevent excessive steering during cornering. Therefore, it is possible to improve stability of direction of the scooter also during cornering.
  • the lower steering shaft is configured as to have a negative caster angle A, it is possible to provide a sufficient and reasonable level of self-aligning torque in particular at lower speed range, e.g. below 10km/h. Therefore, it is possible to improve stability of direction of the scooter in particular at lower speed range.
  • the negative caster angle A is from -20° to -8°, it is possible to improve the ride quality without sacrificing stability of the scooter, in particular at lower speed range, e.g. below 10 km/h.
  • this negative caster angle A is less than -20°, there is a risk that the steering effort becomes too heavy which leads the ride quality of the scooter lower. If this negative caster angle A is more than -8°, there is a risk that the steering effort becomes too light which leads instability of the scooter. By setting this negative caster angle A from -20° to -8°, it is possible to improve the ride quality without sacrificing stability of the scooter, in particular at lower speed range, e.g. below 10 km/h.
  • the negative caster angle A is preferably from -12° to -8°.
  • the offset d is from 25 mm to 50 mm.
  • this offset d is less than 25 mm, there is a risk that the self-aligning torque generated becomes too small which leads instability of the scooter. If this offset d is more than 50 mm, there is a risk that the self-aligning torque generated becomes too much which leads difficulty to turn the scooter.
  • the offset d is preferably from 25 mm to 40 mm.
  • the negative caster angle A in degrees and the offset d in millimeters satisfies following relationship: -400 ⁇ A ⁇ d ⁇ -300
  • this value is smaller than -400, there is a risk that the scooter becomes instable at a trajectory from straight line to cornering or vice versa due to too high self-aligning torque, and also design of the scooter combining the negative caster angle A and the offset d becomes difficult. If this value is bigger than -300, there is a risk that stability of the scooter in particular at straight line becomes inappropriate due to too small self-aligning torque. By setting this relationship between the negative caster angle A and the offset d between -400 and -300, it is possible to improve stability of direction of the scooter while maintaining easiness of designing the scooter.
  • At least a radially upper portion of the upper steering shaft inclines backward.
  • the upper steering shaft inclines backward as a whole.
  • an angle As between the upper steering shaft and the lower steering shaft is more than or equal to 30°.
  • this angle As between the upper steering shaft and the lower steering shaft is less than 30°, there is a risk that a linearity of generated self-aligning torque in relation with steering angle becomes inappropriate leading a fatigue of the rider.
  • this angle As between the upper steering shaft and the lower steering shaft is less than 30°, it is possible to improve linearity of generated self-aligning torque in relation with steering angle providing comfortable ride of the scooter.
  • the angle As between the upper steering shaft and the lower steering shaft is preferably from 30° to 50°, more preferably from 40° to 50°.
  • the steering joint comprises a universal joint.
  • the universal joint amplifies the self-aligning torque around zero steering angle while reducing the steering angle of a mean to steer a steering assembly like handlebar in particular at higher steering angle, providing better stability and comfortable ride of the scooter.
  • the universal joint is flexible and simple to be assembled, it is also cost effective.
  • FIG. 1 is a schematic side view of a scooter according to an embodiment of the present invention
  • Fig. 2 is an enlarged schematic view showing a portion indicated as II in Fig. 1
  • Fig. 3 is an enlarged schematic view showing a portion indicated as III in Fig. 1;
  • FIG. 1 is a schematic side view of a scooter according to an embodiment of the present invention.
  • Fig. 2 is an enlarged schematic view showing a portion indicated as II in Fig. 1.
  • Fig. 3 is an enlarged schematic view showing a portion indicated as III in Fig. 1.
  • the scooter 1 is a scooter comprising a main body 2 configured to support a rider.
  • the main body 2 comprising a steering support 23 including an upper steering support 21 and a lower steering support 22 for supporting a steering assembly 4, a folding pivot 24 enables to fold the steering assembly 4 toward a rear wheel assembly 3, a rear wheel support 25 where the rear wheel assembly 3 is rotatingly coupled to the main body 2 around a rear wheel axis (not shown), and a mud guard 26 which acts also as a rear brake actuator.
  • the steering assembly 4 includes an upper steering shaft 5 rotationally coupled to the main body 2 through the upper steering support 21 of the steering support 23, a lower steering shaft 6 rotationally coupled to the main body 2 through the lower steering support 22 of the steering support 23 about a steering pivot axis SPA (shown in Figs. 2 and 3), and a steering joint 7 connecting the upper steering shaft 5 and the lower steering shaft 6.
  • the upper steering shaft 5 comprises a handlebar 51 at its upper extremity which would be held by rider’s hand(s) for controlling the scooter 1.
  • the lower steering shaft 6 is configured as to have a negative caster angle A.
  • This negative caster angle A is set from -20° to -8°. In the present embodiment, the negative caster angle A is -12°.
  • the scooter 1 also comprising a front wheel assembly 9 rotatingly coupled to a front wheel support 8 about a front wheel axis (not shown), the front wheel support 8 being pivotally coupled to the lower steering shaft 6.
  • the front wheel support 8 having a front brake 81 for stopping a rotation of the front wheel assembly 9.
  • the front wheel support 8 is configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly 9 with ground G, the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly 9 with ground G.
  • This offset d is set from 25 mm to 50 mm. In the present embodiment, the offset D is 30 mm.
  • the negative caster angle A in degrees and the offset d in millimeters satisfies following relationship: -400 ⁇ A ⁇ d ⁇ -300
  • the upper steering shaft 5 inclines backward.
  • the upper steering shaft 5 inclines backward as a whole.
  • the upper steering shaft 5 and the lower steering shaft 6 creating an angle As, which is more than or equal to 30°.
  • the steering joint 7 connecting the upper steering shaft 5 and the lower steering shaft 6 comprises a device allowing two rotating shafts to be linked together (not shown), preferably such the device is a universal joint (not shown). In the present embodiment, this angle As between the upper steering shaft 5 and the lower steering shaft 6 is 40°.
  • the front wheel support 8 is configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly 9 with ground G, and the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly 9 with ground G, the front wheel assembly 9 produces a self-aligning torque, a torque tends to steer the wheel toward the direction in which the scooter 1 is traveling, in particular at higher speed range, e.g. above 10 km/h. Therefore, it is possible to improve stability of direction of the scooter 1 in particular in straight line and at higher speed range.
  • the self-aligning torque produced would also act as to prevent excessive steering during cornering. Therefore, it is possible to improve stability of direction of the scooter 1 also during cornering.
  • the lower steering shaft 6 is configured as to have a negative caster angle A, it is possible to provide a sufficient and reasonable level of self-aligning torque in particular at lower speed range, e.g. below 10km/h. Therefore, it is possible to improve stability of direction of the scooter 1 in particular at lower speed range.
  • the negative caster angle A is from -20° to -8°, it is possible to improve the ride quality without sacrificing stability of the scooter 1, in particular at lower speed range, e.g. below 10 km/h.
  • this negative caster angle A is less than -20°, there is a risk that the steering effort becomes too heavy which leads the ride quality of the scooter 1 lower. If this negative caster angle A is more than -8°, there is a risk that the steering effort becomes too light which leads instability of the scooter 1.
  • the negative caster angle A is preferably from -12° to -8°.
  • the offset d is set from 25 mm to 50 mm, it is possible to improve stability of the scooter 1 without sacrificing easiness for turning the scooter 1, in particular at higher speed range, e.g. above 15 km/h.
  • this offset d is less than 25 mm, there is a risk that the self-aligning torque generated becomes too small which leads instability of the scooter 1. If this offset d is more than 50 mm, there is a risk that the self-aligning torque generated becomes too much which leads difficulty to turn the scooter 1.
  • the offset d is preferably from 25 mm to 40 mm.
  • this value is smaller than -400, there is a risk that the scooter 1 becomes instable at a trajectory from straight line to cornering or vice versa due to too high self-aligning torque, and also design of the scooter 1 combining the negative caster angle A and the offset d becomes difficult. If this value is bigger than -300, there is a risk that stability of the scooter 1 in particular at straight line becomes inappropriate due to too small self-aligning torque.
  • the upper steering shaft 5 inclines backward as a whole.
  • the angle As between the upper steering shaft 5 and the lower steering shaft 6 is more than or equal to 30°, it is possible to improve linearity of generated self-aligning torque in relation with steering angle providing comfortable ride of the scooter 1.
  • this angle As between the upper steering shaft 5 and the lower steering shaft 6 is less than 30°, there is a risk that a linearity of generated self-aligning torque in relation with steering angle becomes inappropriate leading a fatigue of the rider.
  • the angle As between the upper steering shaft 5 and the lower steering shaft 6 is preferably from 30° to 50°, more preferably from 40° to 50°.
  • the steering joint 7 comprises a universal joint, it is possible to easily and effectively transmit steering torque between the upper steering shaft 5 and the lower steering shaft 6 which have angular misalignment leading improvement on ride quality.
  • the universal joint amplifies the self-aligning torque around zero steering angle while reducing the steering angle of a mean to steer a steering assembly like handlebar 51 in particular at higher steering angle, providing better stability and comfortable ride of the scooter.
  • the universal joint is flexible and simple to be assembled, it is also cost effective.
  • the universal joint is made by two fork-shaped hubs, one coupled to the upper steering shaft 5 and another coupled to the lower steering shaft 6, connected together by a crosspiece. More preferably an axis of the hub coupled with the lower steering shaft 6 extends horizontally as aligned with lateral orientation when driving in a straight line, and an axis of the hub coupled with the upper steering shaft 5 inclines on a plane perpendicular to ground and containing longitudinal direction.
  • the scooter 1 may be provided with other parts useful for safety or required by law, for example headlight, side stands, etc.
  • the Example was a scooter as described in the above embodiment provided with the negative caster angle A of -12° and the offset d of 30 mm.
  • the Reference was a conventional decathlon type scooter provided with a positive caster angle of 14° and an offset d of 5 mm.
  • the Comparative Example was a scooter similar to the Example but provided with the negative caster angle A of -6° and the offset d of 33 mm.
  • the scooters were tested on a paved test course via a well-trained rider and overall ride quality especially on both straight line and cornering stability were subjectively evaluated against the Reference.
  • the well-trained rider evaluated that the Example was better than the Reference in any stability of the direction, and the Comparative Example was equal to or a little worse than the Reference. As seen from the results, the Example show improvement on stability of the direction of the scooter.
  • scooter 2 main body 21 upper steering support 22 lower steering support 23 steering support 24 folding pivot 25 rear wheel support 26 mud guard 3 rear wheel assembly 4 steering assembly 5 upper steering shaft 51 handlebar 6 lower steering shaft 7 steering joint 8 front wheel support 81 front brake 9 front wheel assembly

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Steering Devices For Bicycles And Motorcycles (AREA)

Abstract

The present invention provides a scooter (1) comprising a main body (2), a rear wheel assembly (3) and a steering assembly (4) that includes an upper steering shaft (5) rotationally coupled to the main body, a lower steering shaft (6) rotationally coupled to the main body about a steering pivot axis SPA, the lower steering shaft being configured as to have a negative caster angle A, a steering joint (7) connecting the upper steering shaft and the lower steering shaft, and a front wheel assembly (9) rotatingly coupled to a front wheel support (8) about a front wheel axis, the front wheel support being pivotally coupled to the lower steering shaft, wherein the front wheel support is configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with the ground and a point of contact of the front wheel assembly with the ground, the point of contact of virtual extension line of the steering pivot axis SPA with the ground is located longitudinally frontal to the point of contact of the front wheel assembly with the ground, the negative caster angle is from -20° to -8°.

Description

A STABLE SCOOTOR
The present invention relates to a scooter and in particular a scooter providing improvement on its stability.
A scooter, a kickboard or alike, assisted electrically, by engine or not, is an increasingly used as a means of urban transportation, that has a good efficiency of payload per vehicle mass. The scooter’s characteristics such as light and very compact when folded makes it possible to carry under the arm during public transportation or to be placed in an office, eliminating a need for a garage space while allowing to travel in a city traffic at around 25 km/h.
In reality practical usage of the scooter is accidental due to its other characteristics, such as small wheel diameters with limited ground clearance, negligible gyroscopic effect also due to small wheel diameters, standing posture requiring a firm grip on handlebars to control vehicle attitude, which leads instability of the direction.
In order to improve stability of scooter, it is known that change on geometrical configuration around a front wheel is effective. Various solutions have been proposed to improve stability of scooter.
EP1240073 discloses a scooter having a fork which is rearwardly angled with respect to a fork rod for positioning handlebars at a great height making it possible to tilt a steering column with little physical force.
DE102012204915 discloses a scooter having a steering system for easily and safely steer with just one hand while eliminating several disadvantages such as rapid fatigue, uncomfortable to wear.
EP1240073 DE102012204915
However with the solutions disclosed in these documents, improvement on stability of the vehicle is not satisfactory. Thus there is a desire to further improve stability of the direction.
Therefore, there is a need for a scooter which provides improvement on stability of the direction.
Definitions:
A “caster angle” is a tilt angle of a steering pivot axis compared to an imaginary vertical line as viewed from the side. When the steering pivot axis slants forwardly, it is called as a “negative caster angle”.
An “offset”, also called as a “caster trail” is a distance from the intersection of the steering pivot axis with ground to the center of the wheel-to-ground contact area.
A “wheel assembly” is an assembly of a rotating object intended to contact with ground and rotating around an axis of rotation. The wheel assembly may be a quasi-rigid or elastic wheel sole, a wheel enveloped on its outer circumference by rubber or plastic-like material, a wheel with a tire, pneumatic or not, mounted onto the wheel.
It is thus an object of the invention to provide a scooter which provides improvement on stability of the direction.
The present invention provides a scooter comprising a main body configured to support a rider, a rear wheel assembly rotatingly coupled to the main body around a rear wheel axis, a steering assembly that includes an upper steering shaft rotationally coupled to the main body through an upper steering support, a lower steering shaft rotationally coupled to the main body through a lower steering support about a steering pivot axis SPA, the lower steering shaft being configured as to have a negative caster angle A, a steering joint connecting the upper steering shaft and the lower steering shaft, a front wheel assembly rotatingly coupled to a front wheel support about a front wheel axis, the front wheel support being pivotally coupled to the lower steering shaft, the front wheel support being configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly with ground G, the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly with ground G.
This arrangement provides an improvement on stability of the direction of the scooter.
Since the front wheel support being configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly with ground G, and the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly with ground G, the front wheel assembly produces a self-aligning torque, a torque tends to steer the wheel toward the direction in which the scooter is traveling, in particular at higher speed range, e.g. above 15 km/h. Therefore, it is possible to improve stability of direction of the scooter in particular in straight line and at higher speed range.
The self-aligning torque produced would also act as to prevent excessive steering during cornering. Therefore, it is possible to improve stability of direction of the scooter also during cornering.
If the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally backward to the point of contact of the front wheel assembly with ground G, a rider has to control a mean to steer a steering assembly like handlebar by applying a steering torque to a direction opposite to the direction the rider has to follow due to its kinematics, which is not natural for the rider. By setting the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly with ground G, it is possible to provide a natural steering behavior.
Since the lower steering shaft is configured as to have a negative caster angle A, it is possible to provide a sufficient and reasonable level of self-aligning torque in particular at lower speed range, e.g. below 10km/h. Therefore, it is possible to improve stability of direction of the scooter in particular at lower speed range.
Since the negative caster angle A is from -20° to -8°, it is possible to improve the ride quality without sacrificing stability of the scooter, in particular at lower speed range, e.g. below 10 km/h.
If this negative caster angle A is less than -20°, there is a risk that the steering effort becomes too heavy which leads the ride quality of the scooter lower. If this negative caster angle A is more than -8°, there is a risk that the steering effort becomes too light which leads instability of the scooter. By setting this negative caster angle A from -20° to -8°, it is possible to improve the ride quality without sacrificing stability of the scooter, in particular at lower speed range, e.g. below 10 km/h.
The negative caster angle A is preferably from -12° to -8°.
In another preferred embodiment, the offset d is from 25 mm to 50 mm.
If this offset d is less than 25 mm, there is a risk that the self-aligning torque generated becomes too small which leads instability of the scooter. If this offset d is more than 50 mm, there is a risk that the self-aligning torque generated becomes too much which leads difficulty to turn the scooter. By setting this offset d from 25 mm to 50 mm, it is possible to improve stability of the scooter without sacrificing easiness for turning the scooter, in particular at higher speed range, e.g. above 15 km/h.
The offset d is preferably from 25 mm to 40 mm.
In another preferred embodiment, the negative caster angle A in degrees and the offset d in millimeters satisfies following relationship:
-400 < A × d < -300
If this value is smaller than -400, there is a risk that the scooter becomes instable at a trajectory from straight line to cornering or vice versa due to too high self-aligning torque, and also design of the scooter combining the negative caster angle A and the offset d becomes difficult. If this value is bigger than -300, there is a risk that stability of the scooter in particular at straight line becomes inappropriate due to too small self-aligning torque. By setting this relationship between the negative caster angle A and the offset d between -400 and -300, it is possible to improve stability of direction of the scooter while maintaining easiness of designing the scooter.
In another preferred embodiment, at least a radially upper portion of the upper steering shaft inclines backward.
According to this arrangement, it is possible to move the rider backwards thus put more weight to rear wheel assembly in order to limit a risk of forward tipping when braking strongly or impact. This also help to improve braking power of the front wheel assembly.
Preferably the upper steering shaft inclines backward as a whole.
In another preferred embodiment, an angle As between the upper steering shaft and the lower steering shaft is more than or equal to 30°.
If this angle As between the upper steering shaft and the lower steering shaft is less than 30°, there is a risk that a linearity of generated self-aligning torque in relation with steering angle becomes inappropriate leading a fatigue of the rider. By setting this angle As between the upper steering shaft and the lower steering shaft less than 30°, it is possible to improve linearity of generated self-aligning torque in relation with steering angle providing comfortable ride of the scooter.
The angle As between the upper steering shaft and the lower steering shaft is preferably from 30° to 50°, more preferably from 40° to 50°.
In another preferred embodiment, the steering joint comprises a universal joint.
According to this arrangement, it is possible to easily and effectively transmit steering torque between the upper steering shaft and the lower steering shaft which have angular misalignment leading improvement on ride quality. The universal joint amplifies the self-aligning torque around zero steering angle while reducing the steering angle of a mean to steer a steering assembly like handlebar in particular at higher steering angle, providing better stability and comfortable ride of the scooter. As the universal joint is flexible and simple to be assembled, it is also cost effective.
According to the arrangements described above, it is possible to provide an improvement on noise performance while maintaining reasonable level on handling performance.
Other characteristics and advantages of the invention arise from the description made hereafter in reference to the annexed drawings which show, as nonrestrictive examples, the embodiment of the invention.
In these drawings:
Fig. 1 is a schematic side view of a scooter according to an embodiment of the present invention; Fig. 2 is an enlarged schematic view showing a portion indicated as II in Fig. 1; Fig. 3 is an enlarged schematic view showing a portion indicated as III in Fig. 1;
Preferred embodiments of the present invention will be described below referring to the drawings.
A scooter 1 according to an embodiment of the present invention will be described referring to Figs. 1, 2 and 3. Fig. 1 is a schematic side view of a scooter according to an embodiment of the present invention. Fig. 2 is an enlarged schematic view showing a portion indicated as II in Fig. 1. Fig. 3 is an enlarged schematic view showing a portion indicated as III in Fig. 1.
The scooter 1 is a scooter comprising a main body 2 configured to support a rider. The main body 2 comprising a steering support 23 including an upper steering support 21 and a lower steering support 22 for supporting a steering assembly 4, a folding pivot 24 enables to fold the steering assembly 4 toward a rear wheel assembly 3, a rear wheel support 25 where the rear wheel assembly 3 is rotatingly coupled to the main body 2 around a rear wheel axis (not shown), and a mud guard 26 which acts also as a rear brake actuator.
As shown in Fig. 1, the steering assembly 4 includes an upper steering shaft 5 rotationally coupled to the main body 2 through the upper steering support 21 of the steering support 23, a lower steering shaft 6 rotationally coupled to the main body 2 through the lower steering support 22 of the steering support 23 about a steering pivot axis SPA (shown in Figs. 2 and 3), and a steering joint 7 connecting the upper steering shaft 5 and the lower steering shaft 6. The upper steering shaft 5 comprises a handlebar 51 at its upper extremity which would be held by rider’s hand(s) for controlling the scooter 1.
As shown in Figs. 1 and 2, the lower steering shaft 6 is configured as to have a negative caster angle A. This negative caster angle A is set from -20° to -8°. In the present embodiment, the negative caster angle A is -12°.
As shown in Figs. 1 and 2, the scooter 1 also comprising a front wheel assembly 9 rotatingly coupled to a front wheel support 8 about a front wheel axis (not shown), the front wheel support 8 being pivotally coupled to the lower steering shaft 6. The front wheel support 8 having a front brake 81 for stopping a rotation of the front wheel assembly 9.
As shown in Figs. 1 and 2, the front wheel support 8 is configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly 9 with ground G, the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly 9 with ground G. This offset d is set from 25 mm to 50 mm. In the present embodiment, the offset D is 30 mm.
The negative caster angle A in degrees and the offset d in millimeters satisfies following relationship:
-400 < A × d < -300
In the present embodiment, as the negative caster angle A is -12° and the offset d is 30 mm, satisfies the relationship with A x d = -360.
As shown in Figs. 1 and 3, at least a radially upper portion of the upper steering shaft 5 inclines backward. In the present embodiment, the upper steering shaft 5 inclines backward as a whole.
As shown in Figs. 1 and 3, the upper steering shaft 5 and the lower steering shaft 6 creating an angle As, which is more than or equal to 30°. The steering joint 7 connecting the upper steering shaft 5 and the lower steering shaft 6 comprises a device allowing two rotating shafts to be linked together (not shown), preferably such the device is a universal joint (not shown). In the present embodiment, this angle As between the upper steering shaft 5 and the lower steering shaft 6 is 40°.
Since the front wheel support 8 is configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly 9 with ground G, and the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly 9 with ground G, the front wheel assembly 9 produces a self-aligning torque, a torque tends to steer the wheel toward the direction in which the scooter 1 is traveling, in particular at higher speed range, e.g. above 10 km/h. Therefore, it is possible to improve stability of direction of the scooter 1 in particular in straight line and at higher speed range.
The self-aligning torque produced would also act as to prevent excessive steering during cornering. Therefore, it is possible to improve stability of direction of the scooter 1 also during cornering.
If the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally backward to the point of contact of the front wheel assembly 9 with ground G, a rider has to control a mean to steer a steering assembly 4 like handlebar 51 by applying a steering torque to a direction opposite to the direction the rider has to follow due to its kinematics, which is not natural for the rider. By setting the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly 9 with ground G, it is possible to provide a natural steering behavior.
Since the lower steering shaft 6 is configured as to have a negative caster angle A, it is possible to provide a sufficient and reasonable level of self-aligning torque in particular at lower speed range, e.g. below 10km/h. Therefore, it is possible to improve stability of direction of the scooter 1 in particular at lower speed range.
Since the negative caster angle A is from -20° to -8°, it is possible to improve the ride quality without sacrificing stability of the scooter 1, in particular at lower speed range, e.g. below 10 km/h.
If this negative caster angle A is less than -20°, there is a risk that the steering effort becomes too heavy which leads the ride quality of the scooter 1 lower. If this negative caster angle A is more than -8°, there is a risk that the steering effort becomes too light which leads instability of the scooter 1.
The negative caster angle A is preferably from -12° to -8°.
Since the offset d is set from 25 mm to 50 mm, it is possible to improve stability of the scooter 1 without sacrificing easiness for turning the scooter 1, in particular at higher speed range, e.g. above 15 km/h.
If this offset d is less than 25 mm, there is a risk that the self-aligning torque generated becomes too small which leads instability of the scooter 1. If this offset d is more than 50 mm, there is a risk that the self-aligning torque generated becomes too much which leads difficulty to turn the scooter 1.
The offset d is preferably from 25 mm to 40 mm.
Since the negative caster angle A in degrees and the offset d in millimeters satisfies following relationship:
-400 < A × d < -300
it is possible to improve stability of direction of the scooter while maintaining easiness of designing the scooter 1.
If this value is smaller than -400, there is a risk that the scooter 1 becomes instable at a trajectory from straight line to cornering or vice versa due to too high self-aligning torque, and also design of the scooter 1 combining the negative caster angle A and the offset d becomes difficult. If this value is bigger than -300, there is a risk that stability of the scooter 1 in particular at straight line becomes inappropriate due to too small self-aligning torque.
Since at least a radially upper portion of the upper steering shaft 5 inclines backward, it is possible to move the rider backwards thus put more weight to rear wheel assembly 3 in order to limit a risk of forward tipping when braking strongly or impact. This also help to improve braking power of the front wheel assembly 9.
Preferably the upper steering shaft 5 inclines backward as a whole.
Since the angle As between the upper steering shaft 5 and the lower steering shaft 6 is more than or equal to 30°, it is possible to improve linearity of generated self-aligning torque in relation with steering angle providing comfortable ride of the scooter 1.
If this angle As between the upper steering shaft 5 and the lower steering shaft 6 is less than 30°, there is a risk that a linearity of generated self-aligning torque in relation with steering angle becomes inappropriate leading a fatigue of the rider.
The angle As between the upper steering shaft 5 and the lower steering shaft 6 is preferably from 30° to 50°, more preferably from 40° to 50°.
Since the steering joint 7 comprises a universal joint, it is possible to easily and effectively transmit steering torque between the upper steering shaft 5 and the lower steering shaft 6 which have angular misalignment leading improvement on ride quality. The universal joint amplifies the self-aligning torque around zero steering angle while reducing the steering angle of a mean to steer a steering assembly like handlebar 51 in particular at higher steering angle, providing better stability and comfortable ride of the scooter. As the universal joint is flexible and simple to be assembled, it is also cost effective.
Preferably the universal joint is made by two fork-shaped hubs, one coupled to the upper steering shaft 5 and another coupled to the lower steering shaft 6, connected together by a crosspiece. More preferably an axis of the hub coupled with the lower steering shaft 6 extends horizontally as aligned with lateral orientation when driving in a straight line, and an axis of the hub coupled with the upper steering shaft 5 inclines on a plane perpendicular to ground and containing longitudinal direction.
The scooter 1 may be provided with other parts useful for safety or required by law, for example headlight, side stands, etc.
The invention is not limited to the examples described and represented and various modifications can be made there without leaving its framework.
In order to confirm the effect of the present invention, one type of Example to which the present invention is applied and other types of Reference and Comparative Example were prepared.
The Example was a scooter as described in the above embodiment provided with the negative caster angle A of -12° and the offset d of 30 mm. The Reference was a conventional decathlon type scooter provided with a positive caster angle of 14° and an offset d of 5 mm. The Comparative Example was a scooter similar to the Example but provided with the negative caster angle A of -6° and the offset d of 33 mm.
The scooters were tested on a paved test course via a well-trained rider and overall ride quality especially on both straight line and cornering stability were subjectively evaluated against the Reference. The well-trained rider evaluated that the Example was better than the Reference in any stability of the direction, and the Comparative Example was equal to or a little worse than the Reference. As seen from the results, the Example show improvement on stability of the direction of the scooter.
1 scooter
2 main body
21 upper steering support
22 lower steering support
23 steering support
24 folding pivot
25 rear wheel support
26 mud guard
3 rear wheel assembly
4 steering assembly
5 upper steering shaft
51 handlebar
6 lower steering shaft
7 steering joint
8 front wheel support
81 front brake
9 front wheel assembly

Claims (6)

  1. A scooter (1) comprising:
    a main body (2) configured to support a rider;
    a rear wheel assembly (3) rotatingly coupled to the main body (2) around a rear wheel axis;
    a steering assembly (4) that includes:
    an upper steering shaft (5) rotationally coupled to the main body (2) through an upper steering support (21);
    a lower steering shaft (6) rotationally coupled to the main body (2) through a lower steering support (22) about a steering pivot axis SPA, the lower steering shaft (6) being configured as to have a negative caster angle A;
    a steering joint (7) connecting the upper steering shaft (5) and the lower steering shaft (6);
    a front wheel assembly (9) rotatingly coupled to a front wheel support (8) about a front wheel axis, the front wheel support (8) being pivotally coupled to the lower steering shaft (6),
    the scooter being characterized in that the front wheel support (8) is configured as to have an offset d between a point of contact of virtual extension line of the steering pivot axis SPA with ground G and a point of contact of the front wheel assembly (9) with ground G, and in that the point of contact of virtual extension line of the steering pivot axis SPA with ground G locates longitudinally frontal to the point of contact of the front wheel assembly (9) with ground G, and in that the negative caster angle A is from -20° to -8°.
  2. The scooter (1) according to Claim 1, wherein the offset d is from 25 mm to 50 mm.
  3. The scooter (1) according to Claim 1 or Claim 2, wherein the negative caster angle A in degrees and the offset d in millimeters satisfies following relationship:
    -400 < A × d < -300
  4. The scooter (1) according to any one of the Claims 1 to 3, wherein at least a radially upper portion of the upper steering shaft (5) inclines backward.
  5. The scooter (1) according to any one of the Claims 1 to 4, wherein an angle As between the upper steering shaft (5) and the lower steering shaft (6) is more than or equal to 30°.
  6. The scooter (1) according to any one of the Claims 1 to 5, wherein the steering joint (7) comprises a universal joint.

PCT/JP2020/041278 2020-11-05 2020-11-05 A stable scootor WO2022097214A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2020/041278 WO2022097214A1 (en) 2020-11-05 2020-11-05 A stable scootor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2020/041278 WO2022097214A1 (en) 2020-11-05 2020-11-05 A stable scootor

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Publication Number Publication Date
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1240073A1 (en) 1999-12-22 2002-09-18 van Ardenne, Robertus A. M. Scooter
CN102490844A (en) * 2011-12-05 2012-06-13 陈和 Double-wheel scooter
DE102012204915A1 (en) 2011-10-19 2013-04-25 Bayerische Motoren Werke Aktiengesellschaft Kick scooter has front wheel having pivot axis which is aligned at acute trailing angle with respect to vertical line, such that caster angle of front wheel is formed
CN202944507U (en) * 2012-11-29 2013-05-22 浙江纺织服装职业技术学院 Scooter faucet capable of swinging front and back
CN212243682U (en) * 2020-08-04 2020-12-29 山西致爱科技有限公司 Multifunctional electric scooter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1240073A1 (en) 1999-12-22 2002-09-18 van Ardenne, Robertus A. M. Scooter
DE102012204915A1 (en) 2011-10-19 2013-04-25 Bayerische Motoren Werke Aktiengesellschaft Kick scooter has front wheel having pivot axis which is aligned at acute trailing angle with respect to vertical line, such that caster angle of front wheel is formed
CN102490844A (en) * 2011-12-05 2012-06-13 陈和 Double-wheel scooter
CN202944507U (en) * 2012-11-29 2013-05-22 浙江纺织服装职业技术学院 Scooter faucet capable of swinging front and back
CN212243682U (en) * 2020-08-04 2020-12-29 山西致爱科技有限公司 Multifunctional electric scooter

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