WO2012153467A1

WO2012153467A1 - Human power driving force detection apparatus for electric bicycle

Info

Publication number: WO2012153467A1
Application number: PCT/JP2012/002657
Authority: WO
Inventors: 憲夫梅沢; 将史川上; 松浦　昭; 植松　秀典
Original assignee: パナソニック株式会社
Priority date: 2011-05-10
Filing date: 2012-04-18
Publication date: 2012-11-15
Also published as: JP2012236431A; JP5127953B2

Abstract

Provided is a human power driving force detection apparatus for an electric bicycle which is capable of minimizing forward and backward power dispersion caused by a pedaling posture and detecting a force effectively which responds to a forward tensile force of a driving force transmission medium such as a chain. An elastic transformation portion (23a) is elastically transformed by a force applied thereto when a crank shaft (7a) is elastically transformed backwards by a reaction force to a forward tensile force of a chain (15) caused by a drive sprocket (13). A distortion detection sensor (24) is disposed at the elastic transformation portion (23a). The elastic transformation portion (23a) and the distortion detection sensor (24) are disposed toward a shaft center (7a') of the crank shaft (7a) from a backward position backwardly slanted from the shaft center (7a') of the crank shaft (7a) when viewed sideways.

Description

Electric bicycle power detection device

The present invention relates to a human power driving force detection device for an electric bicycle.

It has a power storage device such as a battery and an electric motor fed from this power storage device. A human power driving force such as a pedaling force applied to the pedal is detected by a human power driving force detection device including a torque sensor and the like. In addition, an electric bicycle (also referred to as an electric assist bicycle) that can easily travel even on an uphill by applying an auxiliary driving force (assist force) of an electric motor corresponding to the human power driving force is already known.

As an example of the method for detecting the manpower driving force, the crankshaft is twisted when the left and right pedals are depressed, so that the twisted state of the crankshaft and the twist of the cylindrical shaft to which the manpower driving force is transmitted from the crankshaft are described. The state is detected by a magnetostrictive torque sensor (Patent Document 1, etc.). The crankshaft and the cylindrical shaft (referred to as a manpower transmission rotary shaft) are rotatably supported by bearings or the like. Further, the manpower driving force transmitted to the manpower transmitting rotating shaft is transmitted to a driving sprocket (also referred to as a front sprocket, a front gear, or a crank sprocket) as a manpower driving wheel fixed to the manpower transmitting rotating shaft. Then, it is transmitted to the rear wheel via a driving force transmission body such as a chain spanned over the driving sprocket and a driven sprocket (also referred to as a rear sprocket or a rear gear) as a driven wheel attached to the rear wheel. .

However, when detecting a human driving force using the magnetostrictive torque sensor, the magnetostrictive torque sensor requires processing of a magnetostriction generating portion and a coil, which requires a lot of manufacturing cost and difficult process control. However, it has many disadvantages and time.

On the other hand, the human-powered driving force that rotates the rear wheel acts as a force that causes the upper part of the driving force transmission body such as a chain to be moved forward by the driving sprocket. If the force corresponding to the forward tension of the body can be detected, the human driving force for actually driving the rear wheel can be measured. In addition, if it is possible to detect the force corresponding to the forward tension of the driving force transmission body with a simple configuration, it is more desirable because the manufacturing cost can be reduced.

An example of a method for detecting a force corresponding to a forward tension of a driving force transmission body is a torque detection device for an electric bicycle disclosed in Patent Document 2. In a bicycle including an electric bicycle, a force that pulls a driving force transmission body such as a chain forward is generated by a driving sprocket during traveling, and the crankshaft is elastically deformed backward by this reaction force. Therefore, by applying such a phenomenon, as shown in FIG. 18, an elastic deformation portion (support plate portion) 102 that receives and supports the force from which the crankshaft 101 is elastically deformed backward is provided. A strain detection sensor (strain gauge) 103 for detecting the amount of elastic deformation is attached to the elastic deformation portion 102. The elastic deformation portion 102 and the strain detection sensor 103 are disposed at a position immediately behind the crankshaft 101 (specifically, a position on a horizontal line extending from the crankshaft 101 as viewed from the side).

Also, a similar configuration is disclosed in Patent Document 3. In the torque detection device disclosed in Patent Document 3, as shown in FIG. 19, a sensor is provided between a bearing bearing 112 that rotatably supports the crankshaft 111 and a support portion 113 that holds the bearing bearing 112. A sleeve 114 is provided. A sensor chip 115 for detecting distortion is disposed at a position slightly above the horizontal line extending just behind the crankshaft 111 in the sensor sleeve 114 (above an angle θ above the horizontal line).

JP-A-9-95289 Japanese Patent No. 4428825 Japanese Patent Laid-Open No. 11-258078

However, as shown in FIG. 18 and FIG. 19, a strain detection sensor (detecting the amount of elastic deformation of the elastic deformation portion 102 and the sensor sleeve 114 that elastically deforms substantially rearward by receiving the force from the crankshafts 101 and 111). In the configuration having the strain gauge 103 and the sensor chip 115 attached, when the left and right pedals are stepped on, the strain detection sensor 103 other than the effective component that becomes the driving force (rotational torque) through the chain by the pedaling force. As a result, a forward or backward component force that becomes an error signal to the sensor chip 115 is generated. Moreover, since the force that generates this error varies depending on the difference in the pedal angle that the passenger steps on, it is desirable to calibrate to minimize the influence of the force that generates such an error. That is, in an electric bicycle as well as a general bicycle, as shown in FIG. 20, the occupant depresses the pedal P in a front-up state in which the front side is slightly upward in front of the crankshaft K. In many cases, the pedal P is stepped on the rear side of the crankshaft K in a front-down state in which the front side is slightly downward. Therefore, by not depressing the pedal P in the horizontal state in this way, a forward or backward component force that becomes an error signal to the strain detection sensor 103 or the sensor chip 115 is generated. It is preferred to calibrate to minimize force effects.

The present invention solves the above-mentioned problems, and can minimize the influence of the forward and backward component forces caused by the pedaling posture, and can pull the driving force transmission body such as a chain forward. An object of the present invention is to provide a human-powered driving force detection device for an electric bicycle capable of detecting a corresponding force satisfactorily.

In order to solve the above-described problem, the human-powered driving force detection device for an electric bicycle according to the present invention includes a driving sprocket or the like in which a driving force transmitting body such as a chain for rotating and driving a rear wheel rotates together with a crankshaft. In an electric bicycle that spans between a manpower driven wheel body and a driven wheel body attached to a rear wheel and is configured to be able to add an auxiliary driving force based on a manpower driving force by a pedaling force from a pedal, the manpower driving wheel An elastic deformation portion is provided that elastically deforms when the crankshaft is elastically deformed rearward by a reaction force of a force pulling the driving force transmission body forward by the body, and the elastic deformation portion is provided with the elastic deformation portion. A strain detection sensor for detecting the human driving force from the amount of elastic deformation is attached. The elastic deformation portion and the strain detection sensor are viewed from the side, and the driving force is transmitted by the human driving wheel. Characterized in that disposed in the rear position inclined obliquely downward from a line passing through an axis parallel crank axis direction to pull the body forward.

In the above configuration, when the passenger depresses the pedal and travels, the passenger steps on the pedal in the front-up state before the crankshaft, and steps on the pedal in the front-down state behind the crankshaft. There are many. Also, when the pedal is located in front of the crankshaft, the pedaling force is stepped on strongly, so the pedaling force increases.In places where the pedal is located behind the crankshaft, the pedal is only placed on the pedal and not depressed. Since there are many, pedaling force becomes small. Therefore, the strain detection sensor attached to the elastically deforming portion is viewed from the side and is obliquely below the line passing through the axis of the crankshaft parallel to the direction in which the driving force transmitting body is pulled forward by the human power driving wheel. When arranged at an inclined rear position, as viewed from the side, it is parallel to the direction in which the driving force transmission body is pulled forward by the human-powered wheel body, and is disposed at a rear position on a line passing through the axis of the crankshaft. However, it is possible to suppress the influence of the forward and backward component forces resulting from the pedaling posture, and it is possible to detect well the force corresponding to the force pulling the driving force transmission body such as a chain forward.

In other words, while the pedal is stepped on strongly in front of the crankshaft, the pedaling force is reduced in the position behind the crankshaft, so the pedal is located in front of the crankshaft. As a simple example, it is assumed that the pedaling force from the pedal is generated and the pedaling force is not generated at the location located behind the crankshaft, and the pedal is located ahead of the crankshaft. Consider the case where the pedal angle is constant. In this case, the strain detection sensor is placed in an arrangement state in which the force is detected as an inclination state behind the crankshaft along the inclination posture of the pedal, that is, the driving force transmission body such as a chain is detected by the human-powered wheel body. When pulled in the horizontal direction, the pedal is twisted in a horizontal state by disposing the strain detection sensor at a position inclined obliquely below the horizontal line directly behind the crankshaft in side view. As in the case, it is possible to measure a force corresponding to a force that pulls a driving force transmission body such as a chain forward, which is hardly influenced by the inclination angle of the pedal.

As a mounting structure for the strain detection sensor, a bearing that rotatably supports the crankshaft is disposed in a hanger portion fixed to the frame, and the bearing is in contact with the bearing from behind between the hanger portion and the bearing. It is preferable that a sensor support member having an elastically deformable portion that can be elastically deformed is attached, and a strain detection sensor is attached to the elastically deformable portion of the sensor support member. Further, it is preferable that the sensor support member is constituted by a ring-shaped part cut out in a planar shape so that the elastically deforming portion is thin. Further, only one elastic deformation portion and strain detection sensor are provided, and in that case, if the elastic deformation portion and strain detection sensor are provided on the side on which the human-powered wheel body is attached in the left-right direction, the number is small. It can be configured inexpensively with the number of parts. On the other hand, when the elastic deformation portion and the strain detection sensor are provided at a plurality of locations on the side where the human-powered wheel body is attached in the left-right direction and on the side where the human-powered wheel body is not attached in the left-right direction. Although the number of parts increases, the measurement accuracy can be improved.

Further, in the present invention, when the upper portion of the driving force transmission body spanned over the human-powered driving wheel is disposed so as to be lowered toward the rear, this inclined direction and the horizontal line The strain detection sensor and the elastic deformation portion are arranged so that the installation angle of the strain detection sensor is increased by the inclination angle that is the difference from the direction.

With this configuration, the strain detection sensor and the elastically deformable portion can be arranged at a position suitable for the posture where the driving force transmission body is stretched over the manpower driving wheel body, so that it can handle the force that pulls the driving force transmission body forward. Can be detected well.

The strain detection sensor is disposed at an inclination angle of 10 degrees or more obliquely from a line passing through the axis of the crankshaft parallel to the direction in which the driving force transmitting body is pulled forward by the human-powered driving wheel. It is suitable that it is 15 degrees or less.

According to the present invention, the elastically deformable portion and the strain detection sensor are inclined obliquely downward from a line passing through the axis of the crankshaft in parallel with the direction in which the driving force transmission body is pulled by the human-powered driving wheel when viewed from the side. By arranging it in the rear position, it is possible to suppress the influence of the forward and rear component force caused by the pedaling posture, and the force corresponding to the force pulling the driving force transmission body such as the chain forward is good Can be detected.

The whole side view of the electric bicycle provided with the manpower driving force detecting device concerning an embodiment of the invention Side view of the electric bicycle Plan sectional view of the control unit of the electric bicycle Side sectional view of the control unit of the electric bicycle Side sectional view of the human-powered driving force detection device for the electric bicycle The figure which shows roughly the state where the pedaling force is applied from the pedal of the electric bicycle The figure which shows roughly the positional relationship of the crank, bearing and pedal of the electric bicycle The figure which shows the chain tension ratio to the crank angle when the sensor installation angle is 0 degree Diagram showing the chain tension ratio to crank angle when the sensor installation angle is 5 degrees The figure which shows the chain tension ratio to the crank angle when the sensor installation angle is 10 degrees The figure which shows the chain tension ratio to the crank angle when the sensor installation angle is 12.5 degrees The figure which shows the chain tension ratio to the crank angle when the sensor installation angle is 15 degrees The figure which shows the chain tension ratio to the crank angle when the sensor installation angle is 20 degrees The figure which shows roughly the fluctuation state of the pedal angle with respect to the crank angle Diagram showing the relationship between sensor installation angle and chain tension ratio The figure which shows the relationship between manpower driving force, auxiliary driving force, and chain tension (total driving force) The block diagram which shows notionally the arithmetic processing part which calculates the manpower driving force which concerns on the manpower driving force in a control part Side view of a conventional human driving force detection device Side view of other conventional human power driving force detection devices Diagram showing relationship between crankshaft and pedal

Hereinafter, an electric bicycle according to an embodiment of the present invention will be described with reference to the drawings. Note that the left and right in the following description refers to the left and right direction in a state of riding on an electric bicycle and facing forward (traveling direction). 1 in FIG. 1 and FIG. 2 is an electric bicycle according to an embodiment of the present invention. As shown in FIGS. 1 and 2, this electric bicycle 1 includes a metal frame 2 including a head pipe 2a, a front fork 2b, a main pipe 2c, a standing pipe 2d, a chain stay 2e, a seat stay 2f, and the like, A front wheel 3 rotatably attached to the lower end of the fork 2b, a rear wheel 4 rotatably attached to the rear end of the chain stay 2e, a handle 5 for changing the direction of the front wheel 3, a saddle 6, and a crankshaft 7a and a crank arm 7b, a left and right pedal 8 to which a pedaling force as a manual driving force is applied, and an electric motor that generates an auxiliary driving force (assist force). 10, a control unit 11 that performs various electrical controls including the electric motor 10, and a secondary battery that supplies driving electric power to the electric motor 10. A hand operating part (not shown) which is attached to the battery 12, the handle 5 and the like and can be operated by a passenger, etc., and a driving sprocket as a manpower driven wheel attached so as to rotate integrally with the crank 7 (Also referred to as front sprocket, front gear, crank sprocket or crank gear) 13 and driven sprocket (rear sprocket or rear gear, rear wheel) as a driven wheel attached to a hub 9 (also referred to as rear hub) 9 14) (also referred to as a wheel gear), a chain 15 as an endless driving force transmission member spanning the drive sprocket 13 and the driven sprocket 14, and a chain cover 21 that covers the chain 15 and the like from the side. Yes.

When a pedaling force, which is a manpower driving force, is applied to the pedal 8, the crank 7 rotates about the crankshaft 7a, and this manpower driving force is transmitted to the rear wheel via the drive sprocket 13, the chain 15, and the driven sprocket 14. 4 is rotated. In this embodiment, the upper portion of the chain 15 that spans the upper end portion of the drive sprocket 13 and the upper end portion of the driven sprocket 14 is arranged in a posture along the horizontal line. The electric motor 10 is built in a metal hub (hereinafter also referred to as a front hub) 16 disposed at the center of the front wheel 3. In addition, the battery 12 is an example of a capacitor, and a secondary battery is preferable. However, another example of the capacitor may be a capacitor.

As shown in FIG. 3 and FIG. 4, the control unit 11 is a control space portion provided from the center to the rear of the control unit 22 whose outer shell is constituted by the left and

right unit cases

22 a and 22 b. 22c. As shown in FIG. 2, the control unit 22 is arranged at the center lower part of the electric bicycle 1 so as to connect the front end of the chain stay 2e, the rear end of the main pipe 2c, and the lower end of the standing pipe 2d. It is supported in a suspended posture through the support bracket 19 and a cylindrical hanger portion 20 fixed to the support bracket 19 and the like. The control unit 11 includes a control board and a storage circuit that control each component (including the electric motor 10) of the electric bicycle 1. As shown in FIGS. 3 and 4, a crankshaft 7a is inserted in the front portion of the control unit 22 in the lateral direction (left and right horizontal direction), and

bearings

25 and 26 that rotatably support the crankshaft 7a. A crankshaft insertion portion 22d having a substantially cylindrical shape is provided, and most of the crankshaft insertion portion 22d is supported in a state of being inserted into the hanger portion 20. In addition, the drive sprocket 13 is attached to a portion of the right crank arm 7b fitted into the crankshaft 7a so as to rotate integrally with the crankshaft 7a.

The crankshaft insertion portion 22d of the control unit 22 has an elastic deformation portion 23a that is elastically deformed by receiving a force that causes the crankshaft 7a to be elastically deformed rearward by a reaction force of pulling the chain 15 forward by the drive sprocket 13. Is provided. And the distortion detection sensor 24 which detects the said human-power driving force from the elastic deformation amount of this elastic deformation part 23a is attached to this elastic deformation part 23a. The elastic deformation portion 23a is formed on the right side of the crankshaft insertion portion 22d of the control unit 22, that is, on the side close to the drive sprocket 13, and outside the crankshaft insertion portion 22d in the right unit case 22b. It is formed on a part of a substantially ring-shaped sensor ring 23 as a sensor support member, which is disposed between the cylindrical portion forming the shell portion. That is, a part of the outer peripheral side of the sensor ring 23 is notched in a planar shape to form a thin portion, and the thin portion constitutes an elastic deformation portion 23a. The elastic deformation portion 23a and the strain detection sensor 24 allow the force in a direction substantially orthogonal to the plane portion of the elastic deformation portion 23a and the surface portion of the strain detection sensor 24 disposed along the elastic deformation portion 23a with high sensitivity. It is configured so that almost no force is detected (cancelled) in the direction along the plane portion of the elastic deformation portion 23a and the surface portion of the strain detection sensor 24 (the direction substantially perpendicular to the chain 15 and the vertical direction). The ratio of the sensitivity in the direction perpendicular to the plane portion of the elastic deformation portion 23a of the sensor ring 23 and the sensitivity in the direction along the direction has a stress distribution of, for example, 50 to 200: 1. As the strain detection sensor 24, a load sensor using a micro electro mechanical system (MEMS) having high sensitivity and mechanically high proof stress that can be well detected even for a slight displacement, that is, a minute stress is used. It is preferable. Further, in this embodiment, only one elastic deformation portion 23a and strain detection sensor 24 are provided on the side where the human-powered wheel body is attached in the left-right direction, that is, only one.

Here, as shown in FIGS. 4 and 5, the elastic deformation portion 23 a and the strain detection sensor 24 are viewed from the axis 7 a ′ of the crankshaft 7 a as viewed from the side (specifically, from the horizontal line H passing through the axis 7 a ′). More specifically, a line orthogonal to the strain detection sensor 24 is disposed in a posture that passes through the axis 7a ′ of the crankshaft 7a from the rear position. In particular, in this embodiment, the inclination angle which is the angle difference between the horizontal line H passing through the axis 7a ′ of the crankshaft 7a and the line inclined obliquely downward where the strain detection sensor 24 is disposed is 10 degrees or more and 15 degrees. The strain detection sensor 24 is disposed so as to be less than or equal to the degree. In FIG. 5, for the sake of easy understanding, the portion of the human power driving force detection device including the sensor ring 23 and the strain detection sensor 24 is shown in a larger size.

In the above configuration, when the occupant travels while stepping on the pedal 8, as shown in FIG. 6, the occupant steps on the pedal 8 in a front-up state before the crankshaft 7a, and from the crankshaft 7a. In many cases, however, the pedal 8 is stepped forward and lowered. Further, when the pedal 8 is positioned forward of the crankshaft 7a, the pedal 8 is strongly depressed, and therefore the pedaling force is increased. At a position positioned rearward of the crankshaft 7a, only the foot is placed on the pedal 8. Since there are many cases where the pedal is not depressed, the pedaling force is reduced. Therefore, as shown in FIG. 5, when the strain detection sensor 24 attached to the elastic deformation portion 23a is disposed at a position inclined obliquely below the horizontal line directly behind the crankshaft 7a when viewed from the side, Thus, the force of pulling the chain 15 forward can be reduced because the influence of the forward or backward component force caused by the posture of the pedal 8 can be suppressed as compared with the case where it is disposed on the horizontal line immediately behind the crankshaft 7a. Can be detected well.

That is, suppose that the pedaling force from the pedal 8 is generated only at the position where the pedal 8 is located forward of the crankshaft 7a, and the pedaling force to the pedal 8 is not generated at the position positioned behind the crankshaft 7a. As a simple example, let us consider a case where the angle δ of the pedal 8 is constant at a position where the pedal 8 is located in front of the crankshaft 7a. In this case, when the force is detected by setting the strain detection sensor 24 in a tilted state behind the crankshaft 7a along the tilted posture of the pedal 8, that is, a horizontal line extending right behind the crankshaft 7a in side view ( That is, the strain detection sensor 25 is directed from the position inclined parallel to the direction in which the chain 15 is pulled forward by the drive sprocket 13 and obliquely below the axis of the crankshaft 7a toward the axis of the crankshaft 7a. When the pedal 8 is disposed, a force corresponding to the force that pulls the driving force transmission body such as the chain 15 forward, which is not easily affected by the inclination angle δ of the pedal 8, as in the case where the pedal 8 is rolled in a horizontal state. It becomes possible to measure.

Actually, the force acting on the crankshaft 7a and the force pulling the upper portion of the chain 15 forward by the drive sprocket 13 are as follows, in addition to those caused by the angle when the pedal 8 is stepped on. It has various error factors.

That is, (a) a difference in bearing load is applied to the left and right pedals 8 and (a) when the pedal 8 is depressed, a pedal 8 (also referred to as a drive-side pedal 8) located in front of the crankshaft 7a is used. Although a large force is applied, since the foot is also placed on the pedal 8 (also referred to as the non-drive side pedal 8) located behind the crankshaft 7a, an error caused by this foot load also occurs. (C) The upper portion of the chain 15 is spanned across the upper end portion of the drive sprocket 13 and the upper end portion of the driven sprocket 14, but the upper portion of the chain 15 is always arranged in a posture along the horizontal line. It has not been done. Therefore, when the upper portion of the chain 15 is disposed to be inclined, this inclination angle also becomes an error factor.

The compound load and chain based on the pedaling force on the pedal 8 are excluded as the above-mentioned error factors resulting from adding the error factors (A) and (B) above to the error factors resulting from the angle when the pedal 8 is depressed. As shown in FIG. 7, the error rate was obtained using a correlation equation assuming a simplified model of the two-point support structure of the crankshaft 7a. The subscript D means the drive side pedal 8, the subscript N means the non-drive side pedal 8, the subscript L means the left pedal 8, and the subscript R means the right side. The pedal 8 is meant.

The effective length of the crank arm 7b is L, the crank angle (the angle at which the crank arm 7b on which the drive-side pedal 8 is assembled and the line extending right above the crankshaft 7a) is θ degrees, and the pedaling force of the drive-side pedal 8 is Is P _D (Nm), torque is T _D , and pedal angle is δ _D degrees,
T _D = L · P _D · sin (θ + δ _D )
When the pedaling force of the non-drive pedal 8 is P _N (Nm), the torque is T _N , and the pedal angle is δ _N ,
T _N = L · P _N · sin (δ _N + 180−θ) = L · P _N · sin (180 + δ _N + −θ)
= L · P _N · sin (− (θ−δ _N −180))
= -L · P _N · sin (θ-δ _N -180)
= L · P _N · sin (θ-δ _N )
It is.

Further, the horizontal component force P _DH of the pedal 8 on the drive side is P _DH = P _D · sin δ _D
The horizontal component P _NH of the pedal 8 on the non-drive side is P _NH = P _N · sin δ _N
It is.

The chain tension ratio (error ratio of the detection value of the strain detection sensor 24 to the chain tension) ε, which is the ratio of the horizontal component force acting on the right bearing 26 to which the strain detection sensor 24 is attached to the tension of the chain 15, is expressed as follows: It becomes an expression like this. Here, as standard bicycle dimensions, the installation angle (tilt angle) of the strain detection sensor 24 is α degrees, the detection load of the strain detection sensor 24 is P _A (Nm), and the tension of the chain 15 is P _C (Nm). The diameter D of the drive sprocket 13 is 0.133 m, the distance L _O = 84.3 mm between the

bearings

25 and 26 of the crankshaft 7a, the distance L _C = 16.1 mm between the chain 15 and the right bearing 26, The distance L _R between the pedal 8 and the right bearing 26 is 123.3 mm, and the distance L _L between the left pedal 8 and the left bearing 25 is 111.6 mm (see FIG. 7). Also, ε ′ _LA is an error when the left pedal 8 acting on the right bearing 26 is a drive side pedal, and ε ″ _RA is an error when the right pedal 8 acting on the right bearing 26 is a drive side pedal. It is an error.
(Formula 1)
_{_{ε 'LA = P' AS /}} P C
_{= {2.95 · P D · sin} (θ + δ D) · cosα-2.95 · P N · sin (θ-δ N) · cosα + 2.46 · P N · sin (δ N + α) +1.32 · P _D · sin (δ _D −α)} / {(2L / D) · {P _D · sin (θ + δ _D ) −P _N · sin (θ−δ _N )}
And
(Formula 2)
_{_{ε "RA = P" AS /}} P C
= {2.95 · P _D · sin (θ + δ _D ) · cos α−2.95 · P _N · sin (θ−δ _N ) · cos α−2.46 · P _D · sin (δ _D −α) −1 .32 · P _N · sin (δ _N + α)} / {(2L / D) · {P _D · sin (θ + δ _D ) −P _N · sin (θ−δ _N )}
It is.

8 to 13 are diagrams showing the chain tension ratio with respect to the crank angle based on the

equations

1 and 2, respectively. FIG. 8 shows the case where the installation angle α of the strain detection sensor 24 is 0 degree, and FIGS. Reference numeral 13 denotes a case where the installation angle α is 5 degrees, 10 degrees, 12.5 degrees, 15 degrees, and 20 degrees in order. These figures show values when a load five times larger than the load applied to the non-drive pedal 8 is applied to the drive pedal 8.

As shown in FIG. 8, when the installation angle α of the strain detection sensor 24 is 0 degree and the inclination angle δ of the pedal 8 is 0 degree (that is, when the force in the front-rear direction along the horizon does not act) ), In a range where the crank angle θ is about 10 degrees or more, the chain tension ratio is a constant value close to 1.19 times the actual tensile force of the chain 15 (hereinafter also referred to as a ratio reference, and this value is 15 and the distance between the

bearings

25 and 26, that is, the distance between the bearings 25 and 26 (ie, (LC + LO) / LO), and the strain detection sensor 24 stabilizes the actual tensile force of the chain 15 without error. Can be measured. However, as the inclination angle δ of the pedal 8 increases, the chain tension ratio greatly deviates from the ratio reference. Further, as shown in FIGS. 9 to 13, as the installation angle α of the strain detection sensor 24 increases, the chain tension ratio ε when the inclination angle δ of the pedal 8 is large approaches the ratio reference while The chain tension ratio ε when the inclination angle δ of 8 is small is away from the ratio reference.

FIG. 14 is a diagram schematically showing the relationship between the pedal maximum angle and the pedal minimum angle with respect to the crank angle θ, and FIG. 15 is a diagram in the range where the crank angle θ is 60 degrees to 120 degrees (also referred to as the priority crank angle). It is a figure which shows the relationship between the installation angle (alpha) of the distortion detection sensor 24, and chain tension ratio (epsilon). As described above, in many cases, the occupant steps on the pedal 8 in a forwardly raised state in front of the crankshaft 7a when traveling, but when the crank angle is small as shown in FIG. Therefore, the inclination angle (also referred to as pedal angle) δ of the pedal 8 tends to increase. On the other hand, as the crank angle θ increases and approaches 180 degrees (as the pedal 8 approaches directly below), the foot on the pedal 8 and the hip joint are separated from each other, and therefore the pedal angle δ tends to decrease. . Further, when the pedal 8 is in a position directly above or directly below or near the crankshaft 7a as viewed from the side, it is often the case that only a foot is placed and almost no force is applied. Therefore, the reliability of the measurement value of the strain detection sensor 24 is substantially high in the range (practical range) of the pedal angle δ and the crank angle θ (30 ° to 150 °) enclosed by the square frame in FIG. It is preferable to use an installation angle α that reduces the error. Further, since the pedal 8 is often loaded with a large pedaling force when the crank angle θ is in the range of 60 degrees to 120 degrees (critical crank angle), the pedal 8 has an installation angle α that is more reliable in this range. It is particularly preferred to use

The range of the chain tension ratio ε when the electric bicycle 1 is used in the range of the pedal angle δ (−5 degrees to 25 degrees) and the crank angle θ (30 degrees to 150 degrees) is shown in FIGS. When the right (R) pedal is driven and when the left (L) pedal is driven, four side frames A and B are shown, respectively, and the crank angle θ in the range surrounded by these frames A and B is 60 degrees. A rectangular frame C indicates a range of 120 degrees (also referred to as a priority crank angle). The frame A is a range of the chain tension ratio ε corresponding to the crank angle θ of the right pedal 8, and the frame B is a range of the chain tension ratio corresponding to the crank angle θ of the left pedal 8. In the range where the crank angle θ is 60 degrees to 120 degrees (respectively indicated by a rectangular frame C), as shown in FIGS. 10 and 15, when the installation angle α of the strain detection sensor 24 is 10 degrees, the chain tension When the ratio ε is 0.90 to 1.47 and the installation angle α of the strain detection sensor 24 is 12.5 degrees as shown in FIGS. 11 and 15, the chain tension ratio ε is 0.96. As shown in FIGS. 12 and 15, when the installation angle α of the strain detection sensor 24 is 15 degrees, the chain tension ratio ε is 0.97 to 1.53. As described above, when the installation angle α of the strain detection sensor 24 is 10 degrees to 15 degrees, that is, 10 degrees or more and 15 degrees or less, the chain tension ratio ε becomes a value close to the ratio reference. When α is 12.5 degrees, the chain tension ratio ε is the closest value to the ratio reference, and is hardly affected by the horizontal component force related to the inclination angle δ of the pedal 8, and is highly reliable. The value can be measured.

On the other hand, in the range where the crank angle θ is 60 degrees to 120 degrees (represented by the rectangular frame C), as shown in FIGS. 8 and 15, the installation angle α of the strain detection sensor 24 is 0 degrees. The chain tension ratio ε is 0.74 to 1.50, and when the installation angle α of the strain detection sensor 24 is 5 degrees as shown in FIGS. As shown in FIGS. 14 and 15, when the installation angle α of the strain detection sensor 24 is 20 degrees, the chain tension ratio ε is 0.87 to 1.63. Thus, when the installation angle α of the strain detection sensor 24 is 5 degrees or 20 degrees, that is, when the installation angle α is smaller than 10 degrees or larger than 15 degrees, the installation angle α is 10 degrees to 15 degrees. In any case, the chain tension ratio ε is far from the ratio reference and covers a wide range, so that it is easily affected by the horizontal component force related to the inclination angle δ of the pedal 8. However, as compared with the case where the installation angle α of the strain detection sensor 24 is 0 degree, the chain tension ratio ε is close to the ratio reference, so that it is less affected by the horizontal component force related to the inclination angle δ of the pedal 8. That is, it has the effect of reducing the error.

The ratio reference value 1.19 can be converted as a proportionality constant. However, the fluctuation of the chain tension ratio ε between the minimum value and the maximum value of the chain tension ratio ε is an error in the detection value of the strain detection sensor 24. Therefore, an error can be reduced by setting an appropriate set angle. In particular, as shown in FIG. 15, when the installation angle α of the strain detection sensor 24 is 10 degrees to 15 degrees, the chain tension ratio ε becomes a value close to the ratio reference, and the inclination angle δ of the pedal 8 is increased. It can be seen that it is less susceptible to the influence of horizontal component force and can measure highly reliable values.

Further, according to the embodiment of the present invention, the bearing 26 that rotatably supports the crankshaft 7a is housed in the hanger portion 20 fixed to the frame 2 such as the front end portion of the chain stay 2e. A sensor ring 23 as a sensor support member having an elastically deformable portion 23a that abuts the bearing 26 from behind and can be elastically deformed is attached between the shaft 26 and the bearing 26, and a strain detection sensor is attached to the elastically deformable portion 23a of the sensor ring 23. 24 is attached. With this configuration, the force corresponding to the force pulling the chain 15 forward can be detected well, although the configuration is relatively simple. Further, since the configuration is relatively simple, the manufacturing cost can be reduced.

Further, the sensor ring 23 as the sensor support member is constituted by a ring-shaped part cut out in a planar shape so that the elastic deformation portion 23a is thin. Thereby, although it is a simple structure, elastic force deformation is hardly detected with little detection of force acting on the sensor ring 23 in the vertical direction (strictly, force in a direction along the plane portion of the elastic deformation portion 23a). Only the force in the direction substantially perpendicular to the plane portion of the portion 23a and the surface portion of the strain detection sensor 24 can be detected with high sensitivity, and the force corresponding to the force pulling the chain 15 forward can be detected even better. In this way, by using the sensing mechanism component that separates the rotation acting on the bearing 26 and the fluctuating load into only one direction component, only the force corresponding to the force pulling the chain 15 forward can be detected well. .

In the above embodiment, the case where only one elastic deformation portion 23a and one strain detection sensor 24 are provided is described. In this case, there is an advantage that the manufacturing cost and the number of parts can be minimized. is there. However, the present invention is not limited to this. For example, not only the right bearing 26 to which the drive sprocket 13 is attached in the left-right direction but also the left bearing 25 to which the drive sprocket 13 is not attached in the left-right direction has the same configuration. A plurality of elastic deformation portions 23 a and strain detection sensors 24 may be provided, such as a sensor ring 23 having an elastic deformation portion 23 a and a strain detection sensor 24. According to this configuration, although the manufacturing cost and the number of parts are slightly increased, the plurality of elastic deformation portions 23a and the strain detection sensors 24 are used, and arithmetic processing is performed on signals from the plurality of strain detection sensors 24. Thus, the force corresponding to the force pulling the chain 15 forward can be detected with higher accuracy.

In the above embodiment, the case where the upper portion of the chain 15 that spans the upper end portion of the drive sprocket 13 and the upper end portion of the driven sprocket 14 is arranged in a posture along the horizontal line has been described. However, it is not limited to this. That is, when the upper part of the chain 15 spanned over the drive sprocket 13 is disposed so as to be lowered toward the rear, the inclination angle of the difference between the inclined and pulling direction and the horizontal line direction. Therefore, the strain detection sensor 24 and the elastic deformation portion 23a are arranged so that the installation angle α of the strain detection sensor 24 is increased. With this configuration, the relative positions of the upper portion of the chain 15, the strain detection sensor 24, and the elastic deformation portion 23a are the same as those in the above-described embodiment. Therefore, the posture of the chain 15 spanning the drive sprocket 13 The strain detection sensor 24 and the elastic deformation portion 23a can be disposed at a position suitable for the above, and a force corresponding to the force pulling the chain 15 forward can be detected well. In addition, when the upper part of the chain 15 spanned over the drive sprocket 13 is inclined and arranged so as to become higher toward the rear, the inclination angle of the difference between the inclined and pulling direction and the horizontal line direction. Therefore, the strain detection sensor 24 and the elastic deformation portion 23a may be disposed so that the installation angle α of the strain detection sensor 24 decreases. That is, when the strain detection sensor 24 and the elastic deformation portion 23a are viewed from the side, the installation angle is larger than the line passing through the axis 7a ′ of the crankshaft 7a in parallel with the direction in which the drive sprocket 13 pulls the upper portion of the chain 15 forward. What is necessary is just to arrange | position in the back position which inclined in the diagonally downward by (alpha).

In the above embodiment, the case where the electric motor 10 is built in the metal hub 9 disposed at the center of the front wheel 3 is shown, but the present invention is not limited to this. In combination with the portion 11, the motor-driven unit may be disposed at the lower center of the electric bicycle 1. However, in this case, as shown in FIGS. 16 and 17, the chain tension is a total value of the human driving force by the stepping force of the human being who is the passenger and the auxiliary driving force by the electric motor. Therefore, the human driving force is calculated by subtracting the auxiliary driving force by the electric motor from the value measured by the strain detection sensor. FIG. 16 is a diagram showing the relationship between human power driving force, auxiliary driving force, and chain tension (total driving force). In FIG. 16, the region indicated by A is the human power driving force, and the region indicated by B is the electric motor. The auxiliary driving force, a line indicated by C, indicates the chain tension (total driving force) that is the output value (total value) to the rear wheels. FIG. 17 is a block diagram conceptually showing an arithmetic processing unit for calculating the human driving force related to the human driving force in the control unit 11. That is, as shown in FIG. 16, the chain tension (total driving force) measured by the strain detecting sensor 24 is the sum of the human driving force and the auxiliary driving force. Therefore, as shown in FIG. The manual driving force is calculated by subtracting the auxiliary driving force from the chain tension (total driving force) measured by the sensor 24. As shown in FIG. 17, since the auxiliary driving force is substantially proportional to the current value of the electric motor 10, the arithmetic processing unit of the control unit 11 calculates the value of the auxiliary driving force from the current value of the electric motor 10, Used as the value of the auxiliary driving force. Thereby, the human driving force is calculated, and the control unit determines the auxiliary driving force to be output based on the human driving force.

In the above embodiment, as shown in FIG. 3, the drive sprocket 13 rotates integrally with the crankshaft 7a via the portion of the right crank arm 7b fitted into the crankshaft 7a. However, the present invention is not limited to this, and the drive sprocket 13 may be directly attached to the crankshaft 7a.

In the above-described embodiment, the case where the chain 15 is used as the driving force transmission body that transmits the pedaling force from the pedal 8 to the rear wheel 4 is described. However, the present invention is not limited to this. A belt may be used. When a toothed belt (a belt with a driving force transmission tooth) is used, a driving gear is used in place of the driving sprocket 13 as a manpower driving wheel that outputs a manpower driving force, and a rear sprocket 14 is used as a rear wheel. Instead of this, a rear gear may be used.

The present invention can be suitably applied to an electric bicycle that actually travels, but is not limited to this, and can also be applied to a fixed electric bicycle for training installed in a sports gym or the like.

Claims

A driving force transmission body such as a chain for rotationally driving the rear wheel is bridged over a manpower driving wheel body such as a driving sprocket that rotates integrally with the crankshaft and a driven wheel body attached to the rear wheel, In the electric bicycle configured to be able to add an auxiliary driving force based on the human driving force by the pedaling force from the pedal,
An elastically deforming portion that is elastically deformed by receiving a force that the crankshaft is elastically deformed backward by a reaction force of a force that pulls the driving force transmitting body forward by the manpower driven wheel body;
A strain detection sensor that detects the human driving force from the elastic deformation amount of the elastic deformation portion is attached to the elastic deformation portion,
The elastically deformable portion and the strain detection sensor, as viewed from the side, are inclined rearward and obliquely downward from a line passing through the axis of the crankshaft parallel to the direction in which the driving force transmission body is pulled forward by the human-powered driving wheel. A human-powered driving force detecting device for an electric bicycle, characterized in that it is disposed at a position.
A sensor support having an elastically deformable portion that is elastically deformable by abutting the bearing from the rear between the hanger portion and the bearing, and a bearing that rotatably supports the crankshaft is disposed in the hanger portion that is fixed to the frame. 2. A human-power-driving-force detecting device for an electric bicycle according to claim 1, wherein a member is attached, and a strain detection sensor is attached to the elastic deformation portion of the sensor support member.
2. The human-power driving force detection device for an electric bicycle according to claim 1, wherein only one elastic deformation portion and one strain detection sensor are provided.
4. The human power driving force detection device for an electric bicycle according to claim 3, wherein the elastic deformation portion and the strain detection sensor are provided on a side on which the human power driving wheel is attached in the left-right direction.
The elastic deformation portion and the strain detection sensor are provided at a plurality of locations on the side where the human-powered wheel body is attached in the left-right direction and on the side where the human-powered wheel body is not attached in the left-right direction. The human power driving force detection device for an electric bicycle according to claim 1.
2. The human-power-driving-force detecting device for an electric bicycle according to claim 1, wherein the sensor support member is a ring-shaped part cut into a planar shape so that the elastically deforming portion is thin.
When the upper part of the driving force transmission body spanned over the manpower driving wheel is inclined so as to become lower toward the rear, the inclination of the difference between the inclined direction and the horizontal direction is inclined. 2. The human-power driving force detection device for an electric bicycle according to claim 1, wherein the strain detection sensor and the elastic deformation portion are arranged so that the installation angle of the strain detection sensor is increased by the corner.
An inclination angle of the strain detection sensor obliquely downward from a line passing through the axis of the crankshaft parallel to a direction in which the driving force transmitting body is pulled forward by the human-powered driving wheel is not less than 10 degrees and not more than 15 degrees. The human-power driving force detection device for an electric bicycle according to claim 1.