AU777845B2

AU777845B2 - Sensor to detect the pedaling force of a power-assisted bike

Info

Publication number: AU777845B2
Application number: AU32978/02A
Authority: AU
Inventors: Gordon Liao
Original assignee: Unique Product and Design Co Ltd
Current assignee: Unique Product and Design Co Ltd
Priority date: 2002-04-05
Filing date: 2002-04-05
Publication date: 2004-11-04
Anticipated expiration: 2022-04-05
Also published as: AU3297802A

Description

P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE

SPECIFICATION

STANDARD

PATENT

Name of Applicant: Unique Product Design Co., Ltd Actual Inventor Address for service is: Gordon Liao WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR Invention Title: "Sensor to Detect the Pedaling Force of a Power-Assisted Bike" Details of Associated Provisional Application No(s): The following statement is a full description of this invention, including the best method of performing it known to me:- SENSOR TO DETECT THE PEDALING FORCE OF A POWER- ASSISTED BIKE BACKGROUND OF THE INVENTION This invention relates to a sensor to detect the pedaling force of a power-assisted bike, particularly to one that is simple in structure and has lower production costs so as to enhance economic gain.

A sensor of a power-assisted bike (usually an electric bike) is provided to detect the pedaling force and generate signal to a power-assisting transmission system to provide assisting power for a bike so as to enable a rider pedal the bike with less force.

SUMMARY OF THE INVENTION The objective of this invention is to offer a sensor to detect the pedaling force of a 15 power-assisted bike, that is simple in structure and reduces production costs.

According to the present invention, there is provided a sensor to detect a pedaling force of a power-assisted bike comprising a transmission system, a resilient member, an annular magnet device, a Hall sensor and a motor whereby the transmission system comprises at least one pair of helical gears, a first helical gear of said pair being activated by said pedaling force to rotate about a fixed location and a second helical gear of said pair being arranged on a shaft to be driven by the first helical gear such that, as the second helical screw gear rotates, it is displaced laterally along the shaft, a distance of displacement being proportional to a torque of the pedaling force; the resilient member is provided at an end of the second helical gear and arranged such that it is compressed when the second helical gear is displaced; the annular magnet device is connected to the second helical gear in proximity to the Hall sensor, which is attached to a fixed location, such that a distance between the annular magnet device and the Hall sensor varies as the second helical gear is displaced; the Hall sensor detects and produces a voltage signal representative of the distance of displacement and thus the pedaling force; and the voltage signal controls the motor to output assisting power to the bike.

BRIEF DESCRIPTION OF DRAWINGS This invention will be better understood by referring to the accompanying drawings, wherein: Fig. 1 is a cross-sectional view of a pedaling-force sensor installed on a bike in the present invention: Fig.2 is an exploded perspective view of the sensor to detect the pedaling force of a bike in the present invention: Fig.3 is a side, cross-sectional view of the transmission system of a powerassisted bike in the present invention: Fig.4 is side, cross-sectional view of the pedaling-force sensor in the present invention.

:DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 15 A preferred embodiment of a sensor to detect the pedaling force of a power-assisted bike includes a first transmission shaft a one-way ratchet a first (left-handed) helical gear a second transmission shaft a second (right-handed) helical gear oo*o(D), a third (left-handed) helical gear a fourth (right-handed) helical gear a motor and a Hall sensor as main components combined together.

Ends of the first transmission shaft (Al) (A2) are respectively connected to opposed pedal cranks (HI) (H2) of bike so that the first transmission shaft can be activated to rotate when the pedal cranks (H2) are pedalled (by manpower for instance).

The one-way ratchet is axially fitted towards a left-hand end of the first transmission shaft (Al) The ratchet has teeth to permit and transmit counterclockwise motion (when viewed from the left-hand end (Al) towards the end (A2) of the transmission shaft The first (left-handed) helical gear is firmly fitted to the ratchet so that when the first transmission shaft is rotated counterclockwise (when viewed from the left-hand end (Al) of the transmission shaft), the first (left-handed) helical gear also rotates in the same direction.

The second transmission shaft is positioned adjacent to the first transmission shaft and a second (right-handed) helical gear is provided axially. The second (righthanded) helical gear is movable in position along the second transmission shaft (L) and engages with the first (left-handed) helical gear of the first transmission shaft as shown in Fig. 3. Thus, when the first (left-handed) helical gear is activated to rotate counterclockwise (when viewed from the left-hand end (Al) of the first transmission shaft), the second (right-handed) helical gear rotates clockwise.

In addition, the third (left-handed) helical gear is firmly fitted to one side of the second (right-handed) helical gear so that they rotate together in a same direction.

Then, the fourth (right-handed) helical gear is axially fitted on the first transmission shaft The fourth (right-handed) helical gear is arranged so that it meshes with the third (left-handed) helical gear and rotates together with the first left-handed gear in a same direction. The fourth (right-handed) helical gear is axially fitted 5 towards the right-hand end (A2) of the first transmission shaft The side of the fourth (right-handed) helical gear facing the right-hand end (A2) of the first transmission shaft is connected to a chain wheel as shown in Fig.4. This arrangement enables a chain to move so that the rear wheel (K1) of a bike rotates oeo¢ counterclockwise (when viewed from the left-hand end (Al) of the first transmission shaft) and the bike moves forward, as shown in Fig. 1.

When the pedal cranks (HI) (H2) are pedalled, the first transmission shaft is driven to rotate counterclockwise (viewed from the left-hand end (Al) towards the end (A2) of the first transmission shaft the first (left-handed) helical gear also rotates counterclockwise because of the counterclockwise rotatable one-way ratchet (B) coaxially fitted between the first transmission shaft and the first (left-handed) helical gear Meanwhile, the second (right-handed) helical gear and the third (left-handed) helical gear being connected together and fitted around the same transmission shaft are actuated to rotate clockwise (when viewed from the left-hand end (Al) of the first transmission shaft) and synchronously, the fourth (right-handed) helical gear of the first transmission shaft and the chain wheel (G1) connected to each other are activated to rotate counterclockwise and drive the chain and to rotate the rear wheel (K1) of the bike in the same direction so as to move the bike forward.

In the process of transmitting rotational motion, a lateral force occurs when the helical gears are rotating. A lateral force acting towards the left-hand end (Al) of the first transmission shaft is produced when the first (left-handed) helical gear activates the second (right-handed) helical gear to rotate, and another lateral force is produced acting towards the left-hand end (Al) of the first transmission shaft when the third (left-handed) helical gear activates the fourth (right-handed) helical gear to rotate.

There is no locking device provided between the second transmission shaft and the helical gears axially provided thereon. Therefore helical gears and are free to move along the length of second transmission shaft When the pedal cranks (HI) (1-12) are pedalled the second and third helical gears move along the 9.

9 9second transmission shaft towards the left-hand end (equivalent to Al) due to the ooo lateral force. The torque of the pedaling force of the pedal cranks (HI) and (H2) is *o°99 99 9 proportional to the shifting distance of the second and the third screw gears and (E) 15 and can thus be detected.

Further, the width of the second and the third helical gears and is greater than that of the first and the fourth helical gears and in order to ensure a permanent engagement between them. As a result, when the second and the third helical gears (D) and are actuated to rotate and shift axially along the second transmission shaft they still mesh with the first and the fourth helical gears and A resilient member (L1) is fitted around the left-hand end of the second transmission shaft (L).It is arranged such that it is compressed by the second and third helical gears and when they shift due to the effects of the lateral force produced as they rotate. The shifting distance of the second and the third helical gears and is proportional to the torque output of the first transmission shaft The second and the third helical gears and can be forced to return to their original positions on the second transmission shaft by the resilient member (L1).

In order to detect the shifting distance of the second and the third helical gears and an annular magnet device is provided on the left end of the second helical gear The annular magnet device has a ring assembled with an annular magnet A Hall sensor is installed at a position relative to the annular magnet It may be secured on the inner wall of a gear-box casing as shown in Fig.3.

The Hall sensor produces a voltage signal as the second and third helical gears (E) move along the second transmission shaft due to the variation in distance between the Hall sensor and annular magnet The voltage signal is representative of the pedaling force of the pedal cranks (HI) and Thus, the pedaling force is detected in accordance with a variation of the distance between the Hall sensor and the annular magnet The voltage signal controls the motor in order to output an assisting power to the bike.

Gear positioned at the front end of the shaft of the motor activates a speed-decreasing system composed of gears to rotate together with the chain wheel thus reaching a goal of providing assisting power for the bike, as shown in Fig.

S. 4.As described above, the second and the third helical gears and are respectively the "right-handed helical gear only to increase a deflection force in shifting. Therefore, so long as either the first helical gear unit includes a first helical gear and the second helical gear (D) the second helical gear unit includes a third helical gear and the fourth helical gear (F) S* 15 is of helical gears and the other unit can be of straight bevel gears or still of helical gears, a lateral force can equally be produced and applied for detecting the pedaling force of a power-assisted bike when the helical gears are used.

%-As can be understood from the above description, the helical gears and are driven to rotate and produce a lateral force such that the pedaling force is detected and 20 assisting power may be provided for the bike as needs be.

While the preferred embodiment of the invention has been described above, it will be recognized and understood that various modifications may be made that fall within the scope of the claims.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

1. Sensor to detect a pedaling force of a power-assisted bike comprising a transmission system, a resilient member, an annular magnet device, a Hall sensor and a motor whereby the transmission system comprises at least one pair of helical gears, a first helical gear of said pair being activated by said pedaling force to rotate about a fixed location and a second helical gear of said pair being arranged on a shaft to be driven by the first helical gear such that, as the second helical screw gear rotates, it is displaced laterally along the shaft, a distance of displacement being proportional to a torque of the pedaling force; the resilient member is provided at an end of the second helical gear and arranged such that it is compressed when the second helical gear is displaced; S*i the annular magnet device is connected to the second helical gear in proximity Soto the Hall sensor, which is attached to a fixed location, such that a distance between the annular magnet device and the Hall sensor varies as the second S 15 helical gear is displaced; the Hall sensor detects and produces a voltage signal representative of the distance of displacement and thus the pedaling force; and the voltage signal controls the motor to output assisting power to the bike.

2. A sensor to detect a pedaling force of a power assisted bike, substantially as hereinbefore described with reference to the accompanying drawings.

3. A sensor to detect a pedaling force of a power-assisted bike substantially as herein described.