ELECTRIC BIKE WITH POWER ASSISTANCE

Abstract

A power-assisted electric bicycle (1) having an auxiliary drive unit (10) that applies auxiliary torque from an auxiliary motor (15) to a rear wheel (7), comprising: an acceleration sensor (57) that detects acceleration acting on a vehicle body; a cadence sensor (55) that detects pedal rotation speed; and a control section (53) that controls driving of the auxiliary motor (15), wherein the control section (53) calculates a vehicle speed from a detection result of the cadence sensor (55) and the acceleration sensor (57), detects slippage of the rear wheel (7) based on a calculation result of the vehicle speed, and performs control to prevent the slippage.

Description

BACKGROUNDField of the invention

[0001] The present invention relates to a power assisted electric bicycle. background

[0002] For example, the unexamined Japanese patent application, First Publication No. 2023-81343, describes that in a power-assisted electric bicycle, a pitch angle or roll angle of the bicycle is detected using an inertial sensor and used to control an assist motor.

[0003] The unexamined Japanese patent application, first publication number 2016-159754 describes that in a power-assisted electric bicycle, when a motor output is not changed at the time of increasing the speed of a drive wheel, the occurrence of slippage is detected.

[0004] The unexamined Japanese patent application, First Publication No. 2014-128992, describes that in a power-assisted electric bicycle, an auxiliary driving force of a front wheel motor is limited to the time of slip detection, and subsequently, the limit is released when the number of times of pedaling reaches a predetermined number. OVERVIEW

[0005] As described in Japanese Unexamined Patent Application, First Publication No. 2023-81343, Japanese Unexamined Patent Application, First Publication No. 2016-159754, and Japanese Unexamined Patent Application, First Publication No. 2014-128992, various assist systems are employed in power-assisted electric bicycles. In power-assisted electric bicycles, a device that detects a vehicle speed (wheel speed) is typically provided on a wheel or the like, and there are many components other than an auxiliary drive unit. Therefore, to reduce the cost increase of a non-assisted conventional bicycle, a new configuration is desired.

[0006] One aspect of the present invention aims to reduce the number of components and costs in a power-assisted electric bicycle having an electric motor that applies torque to a wheel.

[0007] A first aspect of the present invention is a power-assisted electric bicycle (1) having an auxiliary drive unit (10) that applies auxiliary torque from an auxiliary motor (15) to a rear wheel (7), the power-assisted electric bicycle comprising: an acceleration sensor (57) that detects acceleration acting on a vehicle body; a cadence sensor (55) that detects pedal rotation speed; and a control section (53) that controls driving of the auxiliary motor (15), the control section (53) calculating a vehicle speed from a detection result of the cadence sensor (55) and the acceleration sensor (57), detecting slippage of the rear wheel (7) based on a calculation result of the vehicle speed, and performing control to prevent slippage.

[0008] According to this configuration, by detecting the slippage of the rear wheel and performing anti-slip control based on changes in pedal speed and vehicle speed and acceleration, it is possible to realize rear wheel traction control of the power-assisted electric bicycle. Since the vehicle speed is calculated from the detection result of the cadence sensor and the acceleration sensor, it is not necessary to use the vehicle speed (wheel speed) detection device included in the conventional power-assisted electric bicycle, and it is possible to reduce the manufacturing cost of the power-assisted electric bicycle.

[0009] A second aspect of the present invention is the power-assisted electric bicycle (1) according to the first aspect described above, wherein the control section (53) can determine the slip of the rear wheel (7) in a case where the vehicle speed and the acceleration are reduced as the pedal speed increases.

[0010] According to this configuration, by determining the slip of the rear wheel in the case where both of the vehicle speed and the acceleration are decreased as the pedal speed increases, it is possible to accurately perform rear wheel slip determination based on multiple parameters.

[0011] A third aspect of the present invention is the power-assisted electric bicycle (1) according to the first or second aspect described above, wherein the acceleration sensor (57) may include an inertial measuring unit (57a) that detects acceleration in each of a vehicle front and rear direction, a vehicle left and right direction, and a vehicle up and down direction.

[0012] According to this configuration, by integrating the inertial measurement unit that detects acceleration in multiple directions, it is possible to realize various motor controls such as control according to the side slip of the wheel or control according to the vehicle up and down direction in addition to control according to the acceleration and deceleration of the vehicle.

[0013] A fourth aspect of the present invention is the power-assisted electric bicycle (1) according to the third aspect described above, wherein the inertial measuring unit (57a) can be provided integrally with the auxiliary drive unit (10).

[0014] According to this configuration, by providing the inertial measurement unit integrally with the auxiliary drive unit, it is possible to simplify the arrangement of the inertial measurement unit and easily form the power-assisted electric bicycle.

[0015] A fifth aspect of the present invention is the power-assisted electric bicycle (1) according to the third aspect described above, wherein the control section (53) can determine that a vehicle is jumping when a change in acceleration measured by the inertial measuring unit (57a) is in the up and down direction.

[0016] According to this design, by making it possible to determine that the vehicle is jumping, it is possible to reduce unnecessary support to the rear wheel suspended in the air.

[0017] A sixth aspect of the present invention is the power-assisted electric bicycle (1) according to the third aspect described above, wherein the control section (53) can determine that a wheel is swaying when a change in acceleration measured by the inertial measuring unit (57a) is the left and right direction of the vehicle.

[0018] According to this design, by making it possible to determine that the wheel is swaying, it is possible to perform appropriate drive assistance while preventing side slip of the wheel.

[0019] According to the aspect of the present invention, in a power-assisted electric bicycle having an electric motor that applies torque to a wheel, it is possible to reduce the number of components and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a left side view of a power-assisted electric bicycle according to an embodiment of the present invention. Fig. 2 is a cross-sectional view along an axial direction of an auxiliary drive unit of the power-assisted electric bicycle. Fig. Figure 3A is a side view of the power-assisted electric bicycle at the time of riding with handle. Fig. Figure 3B is a graph showing temporal changes in cadence, vehicle speed, and vehicle acceleration at the time of a grip-operated ride. Fig. 4A is a side view of the power-assisted electric bicycle at the time of occurrence of slippage during acceleration. Fig. Figure 4B is a graph illustrating temporal changes in cadence, vehicle speed, and vehicle acceleration at the time of slippage driving. Fig. 5 is a flowchart illustrating a process of rear wheel traction control. Fig. Figure 6A is a side view of the power-assisted electric bicycle at the time of braking with handle. Fig. Figure 6B is a graph showing temporal changes in the front wheel speed, vehicle speed, and vehicle acceleration at the time of grip braking. Fig. 7A is a side view of the power-assisted electric bicycle at the time of occurrence of slippage during deceleration. Fig. Figure 7B is a graph showing temporal changes in the front wheel speed, vehicle speed, and vehicle acceleration at the time of slip driving. Fig. 8 is a flowchart illustrating a process of anti-lock brake control of a front wheel. Fig. 9 is a configuration view of a rear wheel traction control system. Fig. 10 is a configuration view of a front wheel anti-lock regenerative braking system. BRIEF DESCRIPTION OF REFERENCE NUMBERS 1 power-assisted electric bike 3 Pedal crankshaft 6 front wheel 7 Rear wheel 10 Auxiliary drive unit 15 Auxiliary engine 53 First control area (control area) 55 Cadence sensor 57 Accelerometer 57a Inertial measuring unit 60 front-wheel electric drive device 60A front wheel auxiliary motor 61b Front wheel rotation detection sensor 63 Second tax area 67 Accelerometer 67a Inertial measuring unit S1 rear wheel traction control system S2 front wheel anti-lock regenerative braking system DESCRIPTION OF THE EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Directions such as front, rear, right, and left in the following description are the same as the directions in a vehicle described below unless otherwise indicated. Furthermore, at appropriate places in the drawings used in the following description, an arrow FR indicating a vehicle forward direction, an arrow LH indicating a vehicle leftward direction, and an arrow UP indicating a vehicle upward direction are shown. The term "center" used in the present embodiment includes not only a center between two ends of a target, but also an inner region between two ends of the target.In the following description, it is assumed that a vehicle body of the vehicle is not inclined to a left side or a right side and is in an upright state. < Power-assisted electric bike 1>

[0021] Fig. 1 is a left side view of a power-assisted electric bicycle of one embodiment.

[0022] The Fig. The power-assisted electric bicycle 1 shown in FIG. 1 includes an auxiliary motor 15 (electric-operation drive device) that generates auxiliary power according to a pedaling force applied to the pedal 2. In the power-assisted electric bicycle 1, an auxiliary drive unit 10 is mounted around a pedal crankshaft 3 along a left-and-right direction, and a battery 5 is mounted, for example, along a vehicle body frame 4. In the drawing, reference numeral 6 represents a front wheel, reference numeral 7 represents a rear wheel, reference numeral 8 represents a handle, reference numeral 9 represents a seat, reference numeral 2a represents a pedal crank arm, a line C1 represents a rotational center axis line of the pedal crankshaft 3, and reference numeral 60 represents an electric-operation drive device of the front wheel.Hereinafter, a direction along the axis line C1 is called an axial direction, a direction orthogonal to the axis line C1 is called a radial direction, and a circumferential direction around the axis line C1 is called a circumferential direction. < Auxiliary drive unit 10>

[0023] Fig. 2 is a cross-sectional view taken along the axis direction of the auxiliary drive unit 10 of the power-assisted electric bicycle 1.

[0024] With reference also to Fig. 2, the auxiliary drive unit 10 includes the auxiliary motor 15 formed coaxially with the pedal crankshaft 3, a speed reduction machine 40 similarly formed coaxially with the pedal crankshaft 3 and transmitting a driving force (torque) of the auxiliary motor 15 to the pedal crankshaft 3, and a unitary case 11 that houses the auxiliary motor 15 and the speed reduction machine 40 and is supported by the vehicle body frame 4. The auxiliary drive unit 10 is an electric-operation drive unit having a compact uniaxial structure in which the auxiliary motor 15 and the speed reduction machine 40 are arranged coaxially with the pedal crankshaft 3, and is a drive unit that can be suitably used for the power-assisted electric bicycle 1.

[0025] The unitary housing 11 is divided into left and right housing bodies 12, 13 in a vehicle width direction. The left housing body 12 is formed in a bottom-side cylindrical shape that opens to the right. The right housing body 13 is formed in a bottom-side cylindrical shape that opens to the left. The right housing body 13 has a greater depth in the vehicle width direction than the left housing body 12. The auxiliary motor 15 and the speed reduction machine 40 are housed in a closed space formed by the open portions of the left and right housing bodies 12, 13 that abut each other. Specifically, the auxiliary motor 15 and the speed reduction machine 40 are housed in the right housing body 13. A control board 36, a power supply board 37, and control system components such as sensors are housed in the left housing body 12.The left and right housing bodies 12, 13 are integrally formed as a cast component made of, for example, an aluminum alloy.

[0026] The left housing body 12 has a left side wall 12a facing leftward in a vehicle direction and a left outer peripheral wall 12b extending rightward from an outer periphery of the left side wall 12a (toward the right housing body 13 side). A left bearing portion 22, which supports a sensor shaft 18 described later, and a left side portion of the pedal crankshaft 3 are provided at a center portion of the left side wall 12a via a left bearing 22a.

[0027] The right housing body 13 has a right side wall 13a facing rightward in a vehicle direction, and a right outer peripheral wall 13b extending leftward (toward the left housing body 12 side) from an outer periphery of the right side wall 13a. A right bearing portion 23, which supports an output shaft (unit output member) 19, described later, and a right side portion of the pedal crankshaft 3 via a right bearing 23a, is provided at a center portion of the right side wall 13a.

[0028] The auxiliary motor 15 is an inner rotor type motor. The auxiliary motor 15 includes a stator 15b having a cylindrical shape and fixed to the inside of the right outer peripheral wall 13b of the right housing body 13, and a rotor 15a having a similarly cylindrical shape and disposed on an inner periphery of the stator 15b.

[0029] The auxiliary motor 15 of the embodiment is, for example, a DC motor; however, the type of the motor is not particularly limited.

[0030] A plurality of permanent magnets 15a1 aligned in a circumferential direction are fixed to an outer periphery of the rotor 15a. An input-side gear 41 of the speed reduction machine 40 is supported by an inner periphery of the rotor 15a via an eccentric oscillating bearing 42. The speed reduction machine 40 is formed, for example, from a pair of internally toothed planetary gear mechanisms 40a adjacent to each other in the axial direction. The pair of internally toothed planetary gear mechanisms 40a are arranged to fit the entire width of the auxiliary motor 15 in the axial direction and are arranged so that the entire internally toothed planetary gear mechanism 40a overlaps the auxiliary motor 15 when viewed in the radial direction.Each internally toothed planetary gear mechanism 40a is a mechanism including an input-side gear (a ring gear, an internal gear) 41 and an output-side gear (a planetary gear, an external gear) 45 meshed with a gear tooth on the inner peripheral side of the input-side gear 41, and, for example, a mechanism disclosed in Japanese Patent No. 6910197 can be suitably used by the present applicant.

[0031] The rotor 15a is attached to the right housing body 13 via a pair of retaining rings 16 in the axial direction. The rotor 15a is held by the left and right retaining rings 16 via a rotor bearing 16a. A pair of axial oscillating bearings 42 are arranged between the pair of rotor bearings 16a in the axial direction. The rotor bearing 16a and the oscillating bearing 42, which are adjacent to each other in the axial direction, contact each other via a thrust plate 16b. A pressure sensor 40b, attached to the inner circumference of the rotor 15a, is arranged on the outer side in the axial direction of each rotor bearing 16a. Each pressure sensor 40b is in contact with the adjacent motor bearing 16a from the outer side in the axial direction and can thereby receive a thrust force of the oscillating bearing 42 via the rotor bearing 16a and the thrust plate 16b.

[0032] Base end portions of the left and right pedal crank arms 2a are integrally rotatably mounted to the left and right end portions of the pedal crankshaft 3, respectively. Shafts of the left and right pedals 2 are respectively mounted to the front end portions of the left and right pedal crank arms 2a. A transmission cylinder 17 having a cylindrical shape is supported by an outer periphery of the pedal crankshaft 3. The transmission cylinder 17 is divided in the axial direction in the right case body 13. A left side portion of the transmission cylinder 17 is a sensor shaft 18 inserted into the left case body 12, and a right side portion of the transmission cylinder 17 is an output shaft 19 inserted into the right case body 13.

[0033] An enlarged diameter portion 19a, which surrounds an outer periphery of the right end portion of the sensor shaft 18 with a clearance, is formed at a left end portion of the output shaft 19. Reference numeral 19b in the drawing represents a stepped wall having a flange shape and is formed along the radial direction in a base end (right end) of the enlarged diameter portion 19a. A first one-way clutch 26 is disposed between an inner peripheral surface of the enlarged diameter portion 19a and an outer peripheral surface of a right end portion of the sensor shaft 18. A right end portion of the output shaft 19 projects rightward (toward the outside of the housing) of the right bearing portion 23. A drive pinion 31 is integrally rotatably mounted on a right end portion of the output shaft 19.The drive pinion 31 is included in a chain-type transmission mechanism 34 that connects the pedal crankshaft 3 to the rear wheel 7 together with a driven pinion 32 attached to the rear wheel 7 (drive wheel) and a drive chain 33 having an endless shape and wound around both pinions 31, 32.

[0034] The sensor shaft 18 is supported such that the inner circumference of a left end portion (an end portion in the axial direction) is fitted by a spline or the like to an outer circumference of a left side portion of the pedal crankshaft 3. The sensor shaft 18 is integrally rotatable with the pedal crankshaft 3 in any of the front-and-rear rotation directions. In this regard, an inner circumference of the right end portion (another end portion in the axial direction) of the sensor shaft 18 is rotatably supported by an outer circumference of an intermediate portion from left to right (not limited to a center portion) of the pedal crankshaft 3 via a needle bearing 27. Since the needle bearing 27 is located at an intermediate portion in the axial direction (a longitudinal direction) in the pedal crankshaft 3 and is located between outer circumference protrusion portions of the pedal crankshaft 3, the needle bearing 27 has a semi-split structure and is attached to the pedal crankshaft 3.By disposing the needle bearing 27 between an end portion of the sensor shaft 18 and the pedal crankshaft 3, a structure is obtained in which vibration of the end portion of the sensor shaft 18 is prevented, the accuracy of torque detection described later is improved, and the accuracy of operation of the first one-way clutch 26 is improved. The right end portion of the sensor shaft 18 is disposed in the enlarged diameter portion 19a of the output shaft 19. An outer periphery of the right end portion of the sensor shaft 18 is held by an inner periphery of the enlarged diameter portion 19a of the output shaft 19 via the first one-way clutch 26.

[0035] When the pedal crankshaft 3 rotates in the forward rotational direction relative to the output shaft 19 (a direction in which the power-assisted electric bicycle 1 moves forward), the first one-way clutch 26 allows torque to be transmitted to the output shaft 19 from the pedal crankshaft 3, enabling the power-assisted electric bicycle 1 to travel by a rider's pedaling force. On the other hand, when the output shaft 19 rotates in the forward rotational direction relative to the pedal crankshaft 3 (that is, when the pedal crankshaft 3 rotates in the reverse rotational direction relative to the output shaft 19), a built-in cam in the first one-way clutch 26 is not engaged, and the first one-way clutch 26 is idle, preventing torque transmission.

[0036] A speed reduction machine output member 47, which has a cylindrical shape and supports the output-side gear 45 of the speed reduction machine 40, is arranged on the inner peripheral side of the speed reduction machine 40. The speed reduction machine output member 47 is formed integrally with the output-side gear 45 or has a structure in which an output-side gear 45 is integrally fixed as a separate body. The speed reduction machine output member 47 is arranged to surround the outer periphery of the output shaft 19 with a clearance. A second one-way clutch 28 is arranged between an inner peripheral surface of the speed reduction machine output member 47 and an outer peripheral surface of the output shaft 19.

[0037] The second one-way clutch 28 allows an auxiliary torque of the auxiliary motor 15 to be transmitted from the speed reduction machine output member 47 to the output shaft 19. When the speed reduction machine output member 47 rotates in the forward rotation direction relative to the output shaft 19 (a direction in which the power-assisted electric bicycle 1 is moved forward), a cam integrated in the second one-way clutch 28 is engaged, and the second one-way clutch 28 allows a torque to be transmitted to the output shaft 19. This allows the auxiliary torque of the auxiliary motor 15 to be applied to the output shaft 19.

[0038] On the other hand, when the output shaft 19 rotates above a legal speed up to the legal speed (for example, 24 km / h), a command is issued from the control board 36 to the power supply board 37 so as not to generate torque for the auxiliary motor 15. As a result, the rotor 15a, the speed reduction machine 40, and the speed reduction machine output element 47 do not rotate, the integrated cam is not engaged with the second one-way clutch 28, the second one-way clutch 28 is idling, and the pedaling power assistance from the auxiliary motor 15 is not exerted.

[0039] In the power-assisted electric bicycle 1, when a rider rides by stepping on the pedal 2, the driving force of the pedal crankshaft 3 is transmitted to the sensor shaft 18, the first one-way clutch 26, and the output shaft 19 in this order, and is then transmitted to the rear wheel 7 via the chain-type transmission mechanism 34. At this time, when the auxiliary motor 15 is driven to rotate forward, the driving force is transmitted to the speed reduction machine output member 47 via the speed reduction machine 40, is transmitted to the output shaft 19 via the second one-way clutch 28, and contributes to reducing the pedaling force.

[0040] In the power-assisted electric bicycle 1, the chain-type transmission mechanism 34 does not rotate when idling in a state where the pedal 2 is stopped because the one-way clutch is disposed on a shaft of the rear wheel 7. In the power-assisted electric bicycle 1, at the time of stopping idling, when the pedal crankshaft 3 rotates in the reverse rotation direction relative to the pedal 2, the integrated cam is not engaged with the first one-way clutch 26, and the first one-way clutch 26 is idling, preventing torque transmission.

[0041] A thin tape 35a made of a magnetic alloy is integrally wound around an outer peripheral surface of an intermediate portion in the axial direction of the sensor shaft 18. A torque detection coil 35b, which is held by the left case body 12, is arranged on an outer peripheral side of the thin tape 35a. A magnetostrictive torque sensor 35 is formed from the thin tape 35a and the torque detection coil 35b. That is, by generating shear strain on the thin tape 35a by a torque difference between both end portions in the axial direction in the sensor shaft 18 and detecting the change in the magnetic permeability of the thin tape 35a due to this strain by the torque detection coil 35b, the torque acting on the sensor shaft 18 is detected.

[0042] A torque of the pedal crankshaft 3 is input to a left end portion of the sensor shaft 18, and the input torque is output from a right end portion of the sensor shaft 18 to the output shaft 19 via the first one-way clutch 26. At this time, when a torque of a predetermined value or higher is detected by the magnetostrictive torque sensor 35, the assist motor 15 is driven, and an assist torque is applied to the output shaft 19. This reduces the rotational torque of the pedal crankshaft 3 and thus reduces the pedaling force.

[0043] The drive control of the auxiliary motor 15 is performed by the control board 36 and the power supply board 37 housed in the left case body 12. An MCU (Management Controller Unit) is formed on the control board 36, and a PDU (Power Drive Unit) is formed on the power supply board 37. The MCU outputs a control signal to the PDU and drives the auxiliary motor 15 based on input from the magnetorestrictive torque sensor 35, a rotation sensor (not shown) that detects rotation of the pedal crankshaft 3, and the like. The MCU drives the auxiliary motor 15 and assists the pedaling force when the vehicle speed of the power-assisted electric bicycle 1 is less than a predetermined value and the forward rotation torque of a predetermined value or higher of the pedal crankshaft 3 is detected. <Hinterrad-Traktionssteuerungssystem S1>

[0044] Fig. 9 is a configuration view of a rear wheel traction control system S1 applied to the power-assisted electric vehicle 1.

[0045] As in Fig. As shown in FIG. 9, the rear-wheel traction control system S1 includes main components in the auxiliary drive unit 10. The rear-wheel traction control system S1 includes: a drive unit 51 included in the auxiliary motor 15 and an electric operation control section 51a; an ECU (hereinafter referred to as the first control section 53) included in the MCU of the control board 36; a cadence sensor 55 that detects a pedal rotation speed; and an acceleration sensor 57 (inertial measurement unit 57a) that detects an acceleration acting on a vehicle body.

[0046] The first control section 53 generates an assist torque by the assist motor 15 according to a pedaling force of a driver and a rotational speed of the pedal crankshaft 3. The first control section 53 calculates a vehicle speed from a detection result of the cadence sensor 55 and a detection result of the acceleration sensor 57, detects a slip of the rear wheel 7 based on a calculation result of the vehicle speed, and performs control (rear wheel slip control) of slip prevention of the rear wheel 7.

[0047] The first control section 53 includes: vehicle information holding means (memory) 53a that stores a program for rear-wheel slip control, determination threshold values ​​L1, L2, and the like; vehicle speed detecting means that calculates a vehicle speed based on information such as a tire circumferential length of the rear wheel 7, a speed reduction ratio of the chain-type transmission mechanism 34, a detection result of the cadence sensor 55, and a detection result of the acceleration sensor 57; slip determining means 53c that detects the slip of the rear wheel 7 based on a calculation result of the vehicle speed;and a motor output command section 53d that outputs a control signal to the electric operation control section (PDU) 51a of the auxiliary motor 15 according to a determination result of the slip determination means 53c and controls the drive of the auxiliary motor 15 so that the slip of the rear wheel 7 is prevented.;

[0048] The cadence sensor 55 includes: for example, a cadence speed sensor 55a that detects a magnet rotating integrally with the pedal crankshaft 3 and a magnetic force of the magnet at a fixing position and calculates a pedal speed; and an A / D input circuit 55b that performs analog / digital conversion of the detection result of the cadence speed sensor 55a.

[0049] The acceleration sensor 57 is, for example, an IMU (Inertial Measurement Unit) and includes the inertial measurement unit 57a. The inertial measurement unit 57a detects accelerations in a traveling direction (forward and backward directions), the left and right directions, and a vertical direction (up and down directions) of the vehicle.

[0050] Fig. 3A is a side view of the power-assisted electric bicycle 1 at the time of riding with handle. Fig. Figure 3B is a graph showing temporal changes in cadence, vehicle speed, and vehicle acceleration at the time of a grip-operated ride.

[0051] Furthermore, Fig. 4A is a side view of the power-assisted electric bicycle 1 at the time of occurrence of slippage during acceleration. Fig. Figure 4B is a graph illustrating temporal changes in cadence, vehicle speed, and vehicle acceleration at the time of slippage driving.

[0052] Fig. 5 shows a main process performed by the first control section 53 (control section) when rear wheel traction control of slip prevention in the front and rear direction of the rear wheel 7 is performed.

[0053] As in Fig. 5, first, when the power of the auxiliary drive system is turned on, the control section 53 performs control (normal operation), which generates an auxiliary torque by the auxiliary motor 15 according to a torque input to the pedal crankshaft 3 and a rotational speed of the pedal crankshaft 3 (step Q11).

[0054] When normal operation is started, the control section 53 determines whether a cadence is increased or not (whether an increase rate per hour is increased or not) and whether a vehicle body acceleration is changed or not (whether the acceleration in a forward direction of the vehicle is increased or not). If the determination result in step Q12 is NO (the cadence is not increased) or, for example, if the determination result in step Q13 is NO (the acceleration is unchanged), the routine returns to step Q11. If the determination results of both steps Q12 and Q13 are YES (the cadence is increased and the acceleration is changed), the routine proceeds to step Q14.

[0055] In step Q14, it is determined whether the vehicle speed is changing (or whether an increase rate per hour is decreasing). If the determination result in step Q14 is YES (the increase rate per hour is not decreasing), it is determined that the vehicle is accelerating by grip traveling without rear wheel slippage, and the routine returns to step Q11 without performing slip control, for example. If the determination result in step Q14 is NO (the increase rate per hour is decreasing or is almost constant), it is determined that rear wheel slippage is occurring, and the routine proceeds to the slip control of step Q15 and subsequent steps.

[0056] With reference to the graph of Fig. 3B, in a state where the auxiliary drive system is turned on and activated, when the power-assisted electric bicycle 1 is accelerated by a rider to a desired speed from a stop state of the power-assisted electric bicycle 1 in the grip-running travel (a travel in which the rear wheel 7, which is the drive wheel, does not slip), each of a vehicle speed, a vehicle acceleration, and a cadence increases, so that a line “y = ax” can be drawn according to the lapse of time.

[0057] If, with reference to the graph of Fig. 4B, when the rear wheel 7 changes from a grip state to a slip state (between time t1 and time t2) due to reasons such as a low friction coefficient μ of a road surface, the vehicle speed and vehicle acceleration decrease with the passage of time. Alternatively, the rate of increase per time (slope of the graph) of the vehicle speed and vehicle acceleration decreases, and the speed increase becomes small. Conversely, the rate of increase per time of the cadence (pedal speed) increases, and the speed increase becomes rapid.

[0058] The auxiliary drive system of the embodiment includes: the inertial measurement unit 57a as the acceleration sensor 57 that detects acceleration acting on the vehicle body; the cadence sensor 55 that detects cadence; and the first control section 53 that calculates the vehicle speed based on information such as a tire circumferential length and the speed reduction ratio of the chain-type transmission mechanism 34, which is known in advance, the detection result of the cadence sensor 55, and the detection result of the acceleration sensor 57. The first control section 53 detects the rear wheel slip through a relational expression shown below.

[0059] That is, when a change amount per one control cycle (Δt = t2 - t1) of the vehicle body acceleration is ΔAC = AC2 - AC1, a change amount per control cycle of the cadence is ΔNc = Nc2 - Nc1, and a change amount per control cycle of the vehicle speed is ΔS = S2 - S1, and when the relationship of the following Expression 1 is satisfied, it is determined that slippage occurs at the rear wheel 7. ΔAC=0, ΔS<L1, ΔNc> L2(L1, L2 are determination limits L1, L2)

[0060] Expression 1 is preprogrammed into the vehicle information holding means (memory) 53a of the first control section 53. The vehicle speed is calculated in the vehicle speed detecting means 53b of the first control section 53. A slip determination section of the first control section 53 determines whether the rear wheel 7 is slipping or not from the determination threshold values ​​L1, L2 shown in Expression 1.

[0061] If it is determined from the determination threshold values ​​L1, L2 programmed in the first control section 53 that the rear wheel 7 is slipping, a torque (hereinafter referred to as an auxiliary torque) of the auxiliary motor 15 is reduced by reducing an engine load, and the slip of the rear wheel 7 is prevented. It is then determined whether the slip of the rear wheel 7 is eliminated or significantly reduced (whether ΔS ≥ L1 and ΔNc ≤ L2 or not). If the determination of step Q16 is NO, the routine returns to step Q15, and the engine load and the auxiliary torque are further reduced. If the determination of step Q16 is YES, the routine proceeds to step Q17, the engine load and thus the auxiliary torque are further maintained, and the routine checks how this works.

[0062] Then, it is determined again whether ΔS ≥ L1 and ΔNc ≤ L2, and it is determined whether the slip of the rear wheel 7 is completely resolved or not. If the determination of step Q18 is NO, the routine proceeds to step Q17, the assist torque is maintained, and the routine checks how this works. If the determination of step Q18 is YES, since it is assumed that there is no problem even if the assist torque is reset to an original value, the routine proceeds to step Q19, the engine load and thus the assist torque are increased (restored), and the assist torque is reset to a value before the slip prevention control is performed. As a result, power is supplied to the assist motor 15 as in a normal operation, the assist torque is increased, acceleration assistance of the bicycle is enabled, and the rider can ride (accelerate) the bicycle stably.

[0063] Since the inertial measurement unit 57a is used in the embodiment, it is possible to detect not only the acceleration in the traveling direction of the vehicle, but also the acceleration in the left-right direction and the vertical direction. Accordingly, not only is the skid prevention activated by combining the acceleration in the front-and-rear direction and the left-and-right direction of the vehicle, but also during the period (during jumping) from the time the vehicle jumps until the time the vehicle lands, the idle running of the rear wheel 7 during jumping is prevented by performing motor control similar to the motor control described above based on the programmed determination threshold values ​​L1, L2.

[0064] The cadence sensor 55 is mounted near the pedal crankshaft 3. The inertial measurement unit 57a may preferably be located near the center of the vehicle body. In the embodiment, the inertial measurement unit 57a is located near the cadence sensor 55 and near the pedal crankshaft 3. Likewise, the first control section 53 is mounted near the pedal crankshaft 3. It is preferable to arrange the first control section 53, the cadence sensor 55, and the inertial measurement unit 57a in an integrated manner because the entire assembly can be made compact and a wire harness length can be reduced. Although an operating system of the system is located near the handle or the like, remote from the unit, the operating system may be connected to the unit not only by a wired connection but also using short-range wireless communication such as Bluetooth (Registered Trademark).Furthermore, in addition to the operating system, a configuration can be used in which a driver's mobile device or similar and the unit can be connected wirelessly.

[0065] As described above, a power-assisted electric bicycle 1 described above in the embodiment is a power-assisted electric bicycle 1 including the auxiliary drive unit 10 that applies auxiliary torque to the rear wheel 7 from the auxiliary motor 15 via the pedal crankshaft 3. The power-assisted electric bicycle 1 includes: the acceleration sensor 57 that detects acceleration acting on a vehicle body; the cadence sensor 55 that detects pedal rotation speed; and the first control section 53 that controls the drive of the auxiliary motor 15. The first control section 53 calculates a vehicle speed from a detection result of the cadence sensor 55 and the acceleration sensor 57, detects a slippage of the rear wheel 7 based on a calculation result of the vehicle speed, and performs control to prevent the slippage of the rear wheel 7.

[0066] According to this configuration, by detecting the slippage of the rear wheel 7 and performing slip prevention control based on a change in pedal speed and changes in vehicle speed and acceleration, it is possible to realize traction control of the rear wheel 7 of the power-assisted electric bicycle 1. Since the vehicle speed is calculated from the detection result of the cadence sensor 55 and the acceleration sensor 57, it is not necessary to use the vehicle speed (wheel speed) detection device included in the conventional power-assisted electric bicycle 1, and it is possible to reduce the manufacturing cost of the power-assisted electric bicycle 1.

[0067] In the power-assisted electric bicycle 1 described above, the control section 53 determines the slip of the rear wheel 7 in the case where the vehicle speed and acceleration are reduced as the pedal speed is increased.

[0068] According to this configuration, by determining the slip of the rear wheel 7 in the case where both of the vehicle speed and the acceleration are decreased as the pedal speed increases, it is possible to accurately perform a slip determination of the rear wheel based on a plurality of parameters.

[0069] In the power-assisted electric bicycle 1 described above, the acceleration sensor 57 includes the inertial measuring unit 57a that detects the acceleration in each of the front and rear directions of the vehicle, the left and right directions of the vehicle, and the up and down directions of the vehicle.

[0070] According to this configuration, by integrating the inertial measurement unit 57a that detects acceleration in multiple directions, it is possible to realize various motor controls such as control according to the side slip of the wheel or control according to the vehicle up and down direction in addition to control according to the acceleration and deceleration of the vehicle.

[0071] In the power-assisted electric bicycle 1 described above, the inertial measuring unit 57a is provided integrally with the auxiliary drive unit 10.

[0072] According to this configuration, by providing the inertial measurement unit 57a integrally with the auxiliary drive unit 10, it is possible to simplify the arrangement of the inertial measurement unit 57a and to simply construct the power-assisted electric bicycle 1. In the embodiment, the inertial measurement unit 57a is housed in the unit case 11; however, a configuration may be adopted in which the inertial measurement unit 57a is externally mounted on the outside of the case.

[0073] In the power-assisted electric bicycle 1 described above, the control section 53 determines that a vehicle jumps when a change in acceleration measured by the inertial measuring unit 57a is the vehicle direction up and down.

[0074] According to this configuration, by making it possible to determine that the vehicle is jumping, it is possible to reduce unnecessary assistance to the rear wheel 7 floating in the air.

[0075] In the power-assisted electric bicycle 1 described above, the control section 53 determines that the rear wheel 7 rolls when a change in acceleration measured by the inertial measuring unit 57a is the vehicle direction to the left and right.

[0076] According to this configuration, by making it possible to determine that the rear wheel 7 is lurching, it is possible to perform appropriate drive assistance while preventing side slippage of the rear wheel 7. <Elektrobetrieb-Antriebsvorrichtung des Vorderrads 60>

[0077] Here, the power-assisted electric bicycle 1 of the embodiment may include a front wheel electric-operation drive device 60 provided integrally with a hub portion of the front wheel 6. The front wheel electric-operation drive device 60 functions as an electric motor that applies torque in an acceleration direction to the front wheel 6, for example, at the time of acceleration by a pedaling force, and functions as a generator that applies torque in a deceleration direction to the front wheel 6 at the time of deceleration by a braking operation. <Vorderrad-Antiblockier-Regenerierungsbremssystem S2>

[0078] Fig. 10 is a configuration view of a front wheel anti-lock regenerative braking system S2.

[0079] As in Fig. As shown in Fig. 10, the front wheel anti-lock regenerative braking system S2 includes: an electric-operation drive device 60 of a front wheel; a second ECU (second control section) 63 that controls the drive of the electric-operation drive device 60 of the front wheel; and an acceleration sensor 67 (inertial measurement unit 67a) that detects an acceleration acting on the vehicle body.

[0080] The front wheel electric drive device 60 includes: a front wheel auxiliary motor 60A formed coaxially with the front wheel 6; a front wheel rotation detection sensor 61b (including a Hall element for motor rotation) that detects the rotational speed of the front wheel auxiliary motor 60A and thus of the front wheel 6; and an A / D input circuit 61c that performs analog-to-digital conversion of the detection result of the front wheel rotation detection sensor 61b.

[0081] The second control section 63 is driven in conjunction with the auxiliary motor 15 and applies an auxiliary torque to the front wheel 6 according to, for example, a pedaling force of a driver and a rotational speed of the pedal crankshaft 3. The second control section 63 calculates the vehicle speed from the detection result of the front wheel rotation detection sensor 61b, detects the slip of the front wheel 6 based on the calculation result of the vehicle speed and the detection result of the acceleration sensor 67, and executes control (front wheel slip control) of the slip prevention of the front wheel 6.

[0082] The second control section 63 includes: vehicle information holding means (memory) 63a that stores a program for rear wheel slip control, determination threshold values ​​L3, L4, and the like; vehicle speed detecting means 63b that calculates a vehicle speed based on information such as a tire circumferential length of the front wheel 6 and a detection result of the front wheel rotation detection sensor 61b; slip determining means 63c that detects the slip of the front wheel 6 based on a calculation result of the vehicle speed and a detection result of the inertial measuring unit 67a; and a motor output command section 63d that outputs a control signal to the electric operation control section (PDU) 61a of the front wheel assist motor 60A according to a determination result of the slip determination means 63c and controls the drive of the front wheel assist motor 60A (regenerative operation) so that the slip of the front wheel 6 is prevented.

[0083] A configuration may be adopted in which, for example, the second control portion 63 is formed on the control board 36 together with the first control portion 53 and hardware is used in common, or a configuration may be adopted in which the second control portion 63 is formed as an independent body from the first control portion 53 and the control board 36, and the arrangement flexibility is improved.

[0084] The acceleration sensor 67 is, for example, an IMU and includes the inertial measurement unit 67a. The inertial measurement unit 67a detects accelerations in the traveling direction (forward and backward directions), the left and right directions, and the vertical direction (up and down directions) of the vehicle. The inertial measurement unit 67a of the front-wheel anti-lock regenerative braking system S2 can utilize the inertial measurement unit 57a of the rear-wheel traction control system S1.

[0085] In the power-assisted electric bicycle 1 having the front wheel electric-operation drive device 60, the operation of the front wheel electric-operation drive device 60 is controlled by the second control section 63. The second control section 63 calculates the vehicle speed from the detection result of the front wheel rotation detection sensor 61b, detects the slippage of the front wheel 6 based on the calculation result of the vehicle speed and the detection result of the acceleration sensor 67, and performs anti-slip control of the front wheel 6.

[0086] According to this configuration, by detecting the slippage of the front wheel 6 and performing slip prevention control based on a change in the front wheel rotational speed and changes in the vehicle speed and acceleration, it is possible to realize anti-lock control of the regenerative brake of the front wheel 6 of the power-assisted electric bicycle 1. Since the vehicle speed is calculated from the detection result of the front wheel rotation detection sensor 61b in the front wheel electric operation drive device 60, it is not necessary to use a vehicle speed (wheel speed) detection device included in the conventional power-assisted electric bicycle 1, and it is possible to reduce the manufacturing cost of the power-assisted electric bicycle 1.

[0087] For example, even when the front-wheel electric-drive device 60 is used as a regenerative brake for downhill driving or the like, the inertial measurement unit 67a detects the accelerations in the vehicle's traveling direction, the left-right direction, and the vertical direction, and the rotation detection sensor 61b (a Hall element for motor rotation) of the front-wheel electric-drive device 60 detects the front-wheel rotation speed. The second control section 63 calculates the vehicle speed from a tire circumferential length input in advance and the detection result from the front-wheel rotation detection sensor 61b. Based on the calculation result of the vehicle speed and the detection result of the inertial measurement unit 67a, the slippage of the front wheel 6 is detected, and control (front-wheel slippage control) for preventing slippage of the front wheel 6 is performed.

[0088] Fig. 8 shows the main process performed by a second control section 63 when anti-lock regenerative braking control of the front wheel of the slip prevention or the lock in the front and rear direction of the front wheel 6 is performed at the time of regenerative braking of the front wheel 6.

[0089] As in Fig. 8, in an ON state of the power of the auxiliary drive system and in a state where a regeneration operation of the front wheel electric drive device 60 is possible, for example, in response to a deceleration request such as a braking operation of the driver, the second control section 63 performs control (normal operation) of performing a regeneration operation of the front wheel electric drive device 60, which causes the front wheel electric drive device 60 to function as a generator and generate the braking force at the front wheel 6 by the regeneration brake (step Q21).

[0090] When normal operation is started, the second control section 63 determines whether a front wheel speed is increased or not (whether a reduction rate per hour is decreased or not) and whether a vehicle speed is changed or not (whether the reduction rate per hour is decreased or not). For example, if the determination result in step Q22 is NO (the front wheel speed is not increased) or if the determination result in step Q23 is NO (the vehicle speed is not changed), the routine returns to step Q21. If the determination results of both steps Q22 and Q23 are YES (the front wheel speed is increased and the vehicle speed is changed), the routine proceeds to step Q24.

[0091] In step Q24, it is determined whether the vehicle body acceleration is being changed (or whether acceleration (deceleration) in a vehicle rearward direction is being increased). If the determination result in step Q24 is YES (deceleration is being increased), it is determined that the vehicle is being decelerated by a regenerative brake in a grip state without front wheel slippage, for example, and the routine returns to step Q21 without performing slip control. If the determination result in step Q24 is NO (deceleration is not being increased), it is determined that front wheel slippage is occurring, and the routine proceeds to slip control of step Q25 and subsequent steps.

[0092] With reference to the graph of Fig. 6B, in a state where the auxiliary drive system is turned on and the regeneration operation of the front wheel electric-operation drive device 60 is possible, when a rider decelerates the power-assisted electric bicycle 1 from a state where the vehicle is traveled at a vehicle speed b as a desired speed, when the regeneration brake is generated on the front wheel electric-operation drive device 60 in the grip-running travel (travel in which the front wheel 6 is not locked), each of the vehicle speed, the vehicle acceleration, and the front wheel rotational speed is taken to draw a line “y = -ax + b” with the lapse of time.

[0093] With reference to the graph of Fig. 7B, when the front wheel 6 changes from a grip state to a locked state or slip state (between time t1 and time t2) due to reasons such as a low friction coefficient μ of a road surface, the vehicle speed and vehicle acceleration decrease as time passes. Alternatively, the deceleration rate per time (slope of the graph) of the vehicle speed and vehicle acceleration decreases, and the deceleration rate becomes low. Furthermore, the deceleration rate per time of the rotational speed of the front wheel decreases, and the deceleration rate becomes slow.

[0094] The auxiliary drive system of the embodiment includes: the inertial measurement unit 67a as the acceleration sensor 67, which detects acceleration acting on the vehicle body; the rotation detection sensor 61b (a Hall element for motor rotation or the like) in the front-wheel electric drive device 60, which is installed in the front wheel 6; and the second control section 63, which calculates the vehicle speed from information such as the tire circumferential length, which is known in advance. The second control section 63 detects the front-wheel slip through a relational expression shown below.

[0095] That is, when a change amount per one control cycle (Δt = t2 - t1) of the vehicle body acceleration is ΔAC = AC2 - AC1, a change amount per control cycle of the front wheel rotational speed is ΔNf = Nf2 - Nf1, and a change amount per control cycle of the vehicle speed is ΔS = S2 - S1, and when the relationship of the following Expression 2 is satisfied, it is determined that the rear wheel 6 is locked or slipping occurs. ΔAC=0, ΔS<L3, ΔNf> L4(L3, L4 are determination limits)

[0096] Expression 2 is preprogrammed into the vehicle information holding means (memory) 63a of the second control section 63. The vehicle speed is calculated in the vehicle speed detecting means 63b of the second control section 63. A slip determination section of the second control section 63 determines whether the front wheel 6 is locked or slipping from the determination threshold values ​​L3, L4 shown in Expression 2.

[0097] If it is determined from the determination threshold values ​​L3, L4 programmed in the second control section 63 that the front wheel 6 is locked or slipping, a regeneration torque (hereinafter referred to as a motor regeneration torque) of the electric-operation drive device 60 of the front wheel is reduced by reducing a motor load, and the slippage of the front wheel 6 is prevented. It is then determined whether the lock or slippage of the front wheel 6 is eliminated or significantly reduced (whether ΔS ≥ L3 and ΔNf ≤ L4 or not). If the determination of step Q26 is NO, the routine returns to step Q25, and the motor load and the motor regeneration torque are further reduced. If the determination of step Q26 is YES, the routine proceeds to step Q27, the engine load and thus the motor regeneration torque are further maintained, and the routine checks how this works.

[0098] Then, it is determined again whether ΔS ≥ L3 and ΔNf ≤ L4, and it is determined whether the lock or slip of the front wheel 6 is completely recovered or not. If the determination of step Q28 is NO, the routine returns to step Q27, and the motor regeneration torque is maintained, and the routine checks how this works. If the determination of step Q28 is YES, since it is assumed that there is no problem even if the motor regeneration torque is reset to an original value, the routine proceeds to step Q29, the motor load and thus the motor regeneration torque are increased (restored), and the motor regeneration torque is reset to a value before the slip prevention control was performed. As a result, the motor regeneration torque is generated as in normal operation, the bicycle deceleration assist is activated, and the rider can ride the bicycle stably (decelerate).

[0099] Since the inertial measurement unit 67a is configured to detect acceleration not only in the traveling direction of the vehicle but also in the left-right and vertical directions, it is possible to detect slippage by combining the front-to-rear and left-right directions of the vehicle, even when the front wheel 6 enters a so-called side-slip state into a state where no braking is performed. Therefore, by programming the determination threshold values ​​L3, L4, and the like in the second control section 63 in advance, an assist force of the rear wheel 7 by the assist motor 15 at the time of slippage of the front wheel 6 can be reduced.

[0100] The present invention is not limited to the embodiment described above, and for example, the power-assisted electric bicycle may be a bicycle (including three-wheeled and four-wheeled bicycles) of the type in Fig. 1. The present invention can be applied to a power-assisted electric vehicle that does not have a front-wheel electric drive device.

[0101] The configurations described in this embodiment are only examples of the present invention, and various changes may be made without departing from the scope of the present invention, such as replacing the components of the embodiment with well-known components. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-81343 [0002, 0005] JP 2016-159754 [0003, 0005] JP 2014-128992 [0004, 0005] JP 6910197

[0030]

Claims

[1] Power-assisted electric bicycle (1) comprising an auxiliary drive unit (10) that applies an auxiliary torque from an auxiliary motor (15) to a rear wheel (7), the power-assisted electric bicycle comprising: an acceleration sensor (57) that detects an acceleration acting on a vehicle body; a cadence sensor (55) that detects a pedal speed; and a control area (53) which controls the drive of the auxiliary motor (15), wherein the control section (53) calculates a vehicle speed from a detection result of the cadence sensor (55) and the acceleration sensor (75), detects a slip of the rear wheel (7) based on a calculation result of the vehicle speed, and performs control for slip prevention. [2] The power-assisted electric bicycle (1) according to claim 1, wherein the control section (53) determines the slip of the rear wheel (7) in a case where the vehicle speed and the acceleration are reduced as the pedal speed increases. [3] The power-assisted electric bicycle (1) according to claim 1 or 2, wherein the acceleration sensor (57) comprises an inertial measuring unit (57a) that detects acceleration in each of a front and rear direction of the vehicle, a left and right direction of the vehicle, and an up and down direction of the vehicle. [4] The power-assisted electric bicycle (1) according to claim 3, wherein the inertial measuring unit (57a) is provided integrally with the auxiliary drive unit (10). [5] The power-assisted electric bicycle (1) according to claim 3 or 4, wherein the control section (53) determines that a vehicle is jumping when a change in acceleration measured by the inertial measuring unit (57a) is the vehicle direction up and down. [6] The power-assisted electric bicycle (1) according to any one of claims 3 to 5, wherein the control section (53) determines that a wheel is lurching when a change in acceleration measured by the inertial measuring unit (57a) is the vehicle direction to the left and right.

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