TWI848561B - Centrally-arranged motor of an electrical power assist bicycle - Google Patents

Abstract

The invention discloses a centrally-arranged motor of an electrical power assist bicycle, which is a gear mechanism installed in a casing, a part of an eccentric shaft is fixedly connected to an electric drive device, and one end of the eccentric shaft has two eccentric parts for coupling the two facing planetary gears of the gear mechanism. A crankshaft passes through the axial inner of the eccentric shaft; the crankshaft and the gear mechanism are respectively coupled to a chain disc output shaft by a clutch. A deformation bearing bracket fixedly connected to the casing and coupled to the output shaft of the chain disc through a bearing. In this way, the driving force of the electric drive device and the crankshaft can be transmitted to the output shaft of the chain disc respectively, and the deformation bearing bracket combined with a strain gauge can form a torque detector for measuring the torque on the output shaft of the chain disc.

Description

Mid-mounted motor structure of electric assist bicycle

The present invention relates to the technical field of electric assisted bicycles, and in particular to a mid-mounted motor used in electric assisted bicycles.

Ordinary bicycles use a combination of pedals and cranks to drive the gears and chains to enable the bicycle to move forward. Electric assisted bicycles are equipped with an electric motor as an auxiliary power source, and the force of the motor will provide auxiliary power only when the pedals are pressed, making riding easier and more labor-saving.

The mid-mounted motor of the known electric assisted vehicle mostly uses a planetary gear mechanism as a deceleration mechanism. For example, the planetary gear mechanism includes an inner gear ring with a sun gear installed inside, and the planetary gear meshes with the inner gear ring and the sun gear. In addition, Taiwan TWM 437304 and TWM 384160 both disclose deceleration mechanisms for mid-mounted motors used in electric assisted vehicles, and the planetary gear mechanisms provided by each of the deceleration mechanisms do not have a sun gear.

In addition, the torque sensor of an electric-assisted bicycle may be installed at the point where the rear ditch claw contacts the axle. The transmission force must pass through the chain, flywheel, hub, and axle before it can be transmitted to the sensor. Therefore, it must go through a series of calculations and compensations, and the power output error of the motor is relatively large. The above-mentioned patent case does not disclose the installation of the torque sensor.

The purpose of the present invention is to provide a mid-mounted motor structure for an electric assisted bicycle, which has the effect of simplifying the structure and reducing the volume, and can also reduce the rotational interference between the electric drive and the pedal drive.

To achieve the above-mentioned purpose and effect, the present invention discloses a mid-mounted motor for transmitting an electric drive force and a pedaling force to a gear plate, which comprises: a gear mechanism installed in a housing, comprising at least one planetary gear engaged in a gear ring, two planetary carriers respectively located on two opposite sides of the planetary gear, and a plurality of locking members for locking the two planetary carriers and passing through the planetary gear; an eccentric The spindle includes a shaft tube portion with at least one eccentric portion formed at one end thereof, the eccentric portion being offset relative to the shaft tube portion and being used to extend into the gear mechanism to couple with the planetary gear; an electric drive device having a rotatable rotor and being fixedly connected to a portion of the shaft tube portion of the eccentric shaft; a crankshaft is inserted into the axial inner portion of the eccentric shaft and is matched with a supporting rolling element to couple with the eccentric portion of the eccentric shaft A gap is formed between the inner wall surface of the shaft tube portion of the eccentric shaft and the outer surface of the crank shaft, and no other components are installed in the gap; a chain output shaft is coupled to the gear mechanism through a first clutch, and is coupled to the crank shaft through a second clutch, and the chain output shaft is combined with the gear; a torque detector includes a deformable bearing bracket coupled to the chain output shaft through a bearing, and the deformable bearing The bracket is fixed to the housing; wherein the rotor drives the eccentric shaft and the planetary gear to rotate, and the planetary gear revolves eccentrically in the gear ring, thereby driving the two planetary brackets to rotate and transmitting the driving force to the chain output shaft through the first clutch; the rotational force of the crankshaft is transmitted to the chain output shaft through the second clutch; the torque detector is used to detect the torque on the chain output shaft.

In one embodiment, the number of the planetary gears of the gear mechanism is two, including a first planetary gear and a second planetary gear, the number of the eccentric parts of the eccentric shaft is two, including a first eccentric part and a second eccentric part, the first planetary gear is coupled to the first eccentric part, the second planetary gear is coupled to the second eccentric part, the number of teeth of the first planetary gear and the second planetary gear is less than the number of teeth of the gear ring, and the phase difference of the engagement position of the first planetary gear and the second planetary gear engaging the gear ring is 180 degrees.

In one embodiment, the first clutch and the second clutch are overrunning clutches or pawl clutches.

In one embodiment, the planetary gear has a plurality of through holes, and each through hole is provided with a sleeve assembly inserted in a bushing, the outer diameter of the bushing is smaller than the inner diameter of the through hole, and the locking piece locks the two planetary brackets and the sleeve passing through the through hole of the planetary gear. In addition, the bushing and the sleeve form a rotational fit, and the sleeve and the locking piece form a loose fit.

In one embodiment, the electric drive device includes a stator fixed to the housing, and the rotor is located at the center of the stator.

In one embodiment, a speed detector is further included, which is coupled to the crankshaft and corresponds to the electric drive device.

In one embodiment, the gear ring has an inner gear structure, and the planetary gear has an outer gear structure, and each tooth shape of the inner gear structure and each tooth shape of the outer gear structure are mutually engageable progressive tooth shapes or cycloid tooth shapes.

The following is a detailed description of the preferred embodiments based on the purpose and effect disclosed by the present invention with accompanying diagrams.

100: Mid-mounted motor

110: Shell

111: First shell

112: Second shell

120: Electric drive device

121: Stator

122: Rotor

130: Gear mechanism

131:Ring

131a: Inner teeth

132: First planetary gear

132a: External teeth

132b: Perforation

133: Second planetary gear

133a: External teeth

133b: Perforation

134: First planetary bracket

135: Second planetary bracket

136a: lining

136b: Bushing

137: Locking parts

138: Rolling element

139: Spacer ring

140: Eccentric shaft

141: Axle tube part

142: First eccentric part

143: Second eccentric part

150: Crankshaft

160: Chain output shaft

171: First clutch

172: Second clutch

180: Deformed bearing bracket

180a: Strain gauge

181, 182, 183, 184, 185, 186, 187: Supporting rolling elements

190: Speed detector

200: Gap

Figure 1 is a cross-section of the combined structure of the embodiment of the present invention; Figure 2 is an external view of the eccentric shaft structure of the embodiment of the present invention; Figure 3 is an exploded view of the gear mechanism of the embodiment of the present invention; Figure 4 is a schematic diagram of the combination of the eccentric shaft and the planetary gear of the embodiment of the present invention; Figure 5 is a schematic diagram of the planetary gear and the gear ring of the embodiment of the present invention in the meshing state.

The following referenced figures are for illustrating the preferred embodiments of the present invention. It should be understood that the figures and descriptions are for illustration only and are not intended to limit the present invention. In addition, the terms "first", "second" and "third", "left" and "right", "inside" and "outside", "upper" and "lower" described in the specification are used to clearly illustrate relative positions and are not intended to be limiting.

Please refer to FIG. 1, which shows a cross-sectional structure of a mid-mounted motor 100. The mid-mounted motor 100 includes a housing 110 in which a first housing 111 is connected to a second housing 112, and an electric drive device 120 and a gear mechanism 130 are installed inside the housing 110. The housing 110 also includes an eccentric shaft 140 coupling the electric drive device 120 and the gear mechanism 130, and a crankshaft 150 passes through opposite ends of the housing 110 and passes through the axial inner part of the eccentric shaft 140. The mid-mounted motor 100 further includes a sprocket output shaft 160 with a first clutch 171 coupled to the gear mechanism 130, and the sprocket output shaft 160 with a second clutch 172 coupled to the crankshaft 150, and a deformable bearing bracket 180 fixed to the inside of the housing 110, and the sprocket output shaft 160 passes through the axial center of the deformable bearing bracket 180. The sprocket output shaft 160 is coupled to a sprocket 210, and the two ends of the crankshaft 150 are each connected to a crank 220.

Furthermore, the deformable bearing bracket 180 is provided with a supporting rolling element 181, such as a bearing, coupled to the chain output shaft 160. The deformable bearing bracket 180 may be a disc component, and a strain gauge 180a may be attached to its surface, whereby the whole may be used as a torque detector to detect the torque of the chain output shaft 160 and then send a signal, thereby achieving the function of detecting the moment on the chain output shaft 160. Furthermore, a speed detector 190 is coupled to the crankshaft 150 and corresponds to the electric drive device 120. The speed detector 190 includes but is not limited to a sensing contact point and a set of discs composed of a number of magnets, wherein the discs rotate along with the crankshaft 150. When the magnet passes through the sensing point, it transmits a signal to the controller, which is equivalent to transmitting a timely pedaling frequency signal, and the pedaling frequency is used as the basis for figuring out the movement status.

The first clutch 171 and the second clutch 172 disclosed in the above embodiment are unidirectional elements, which may include but are not limited to an overrunning clutch or a ratchet clutch. Among them, the overrunning clutch is a device with a self-clutching function by utilizing the speed change or the change of the rotation direction of the master and slave parts. In addition, appropriate forms and quantities of supporting rolling elements 182, 183, 184, 185, 186, 187, such as bearings, can be arranged at the preset positions of the assembly forms of each component to couple the corresponding components. For example, the supporting rolling elements 182-184 are installed between the eccentric shaft 140 and the gear mechanism 130; the supporting rolling element 185 is installed between the eccentric shaft 140 and the crank shaft 150; the supporting rolling element 186 is installed between the gear mechanism 130 and the chain output shaft 160; the supporting rolling element 187 is installed between the chain output shaft 160 and the crank shaft 150.

Please refer to Figure 2, which is a structural external view of the eccentric shaft 140. The axial inner part of the eccentric shaft 140 is a channel that penetrates the structure; secondly, the eccentric shaft 140 includes a shaft tube 141 with a predetermined length, and one end of the shaft tube 141 extends to form or connects a first eccentric part 142 and a second eccentric part 143. The first eccentric part 142 and the second eccentric part 143 can be closely connected, and the first eccentric part 142 and the second eccentric part 143 are offset from each other. Furthermore, the first eccentric portion 142 and the second eccentric portion 143 are both eccentric relative to the shaft tube portion 141. In addition, the first eccentric portion 142 and the second eccentric portion 143 are cylindrical and have outer diameters greater than the outer diameter of the shaft tube portion 141.

Please refer to Figure 1 again. The electric drive device 120 includes a stator 121 and a rotor 122, wherein the stator is fixed inside the housing 110, and the rotor 122 is located at the center of the stator 121. After the electric drive device 120 receives power, the rotor 122 can be driven to rotate relative to the stator 121. Secondly, a portion of the shaft tube portion 141 of the eccentric shaft 140 penetrates the rotor 122, and the shaft tube portion 141 is fixed to the rotor 122 in an appropriate manner, so that the rotor 122 can drive the eccentric shaft 140 to rotate. Secondly, the crankshaft 150 passes through the axial inner part of the eccentric shaft 140, and a gap 200 is formed between the crankshaft 150 and the axial inner wall surface of the eccentric shaft 140, especially between the outer surface of the crankshaft 150 and the inner wall surface of the shaft tube 141, and no other components are installed in the gap 200.

Please refer to Fig. 3, which shows an exploded view of the gear mechanism 130. The gear mechanism 130 includes a gear ring 131, a first planetary gear 132, a second planetary gear 133, a first planetary carrier 134 and a second planetary carrier 135, each of which is connected to a rolling element 138. The inner circumference of the gear ring 131 has an inner tooth portion 131a, the outer circumference of the first planetary gear 132 has an outer tooth portion 132a, and the outer circumference of the second planetary gear 133 has an outer tooth portion 133a. The first planetary gear 132 and the second planetary gear 133 are opposite to each other and accommodated in the gear ring 131, and the outer teeth 132a and 133a respectively engage with the inner tooth portion 131a. In addition, a spacer ring 139 is used to be arranged between the two opposite planetary gears 132 and 133, thereby avoiding interference between the two planetary gears 132 and 133 during operation. It is worth noting that the number of teeth of the inner tooth portion 131a of this embodiment is greater than the number of teeth of the outer tooth portions 132a and 133a, thereby forming a small tooth difference form.

Secondly, the first planetary gear 132 and the second planetary gear 133 each have a plurality of through holes 132b and 133b of the through structure. A plurality of bushings 136a and a shaft sleeve 136b are respectively installed in the opposite through holes 132b and 133b, wherein the shaft sleeve 136b is installed in the bushing 136a. The first planetary bracket 134 is used to be arranged on one side (outer side) of the first planetary gear 132, and the second planetary bracket 135 is used to be arranged on one side (outer side) of the second planetary gear 133. A plurality of locking members 137 pass through the combination of the bushing 136a and the shaft sleeve 136b from the first planetary bracket 134 and are locked to the second planetary bracket 135. In this way, the two planetary supports 134, 135 and the two planetary gears 132, 133 are combined into one body by the locking parts 137; secondly, the outer diameter of the bushing 136a is smaller than the inner diameter of the through holes 132b, 133b. According to the combination of the above components, the two end surfaces of the sleeve 136b can contact the two planetary supports 134, 135 respectively, so as to adjust the preload of the rolling element (bearing) 138 on the planetary supports 134, 135. Secondly, the sleeve 136b forms a loose fit with the locking part 137.

Please refer to Figure 4, which shows a schematic diagram of the coupling structure of the eccentric shaft 140 and the first planetary gear 132 and the second planetary gear 133. The first planetary gear 132 is mounted on the first eccentric portion 142, and the second planetary gear 133 is mounted on the second eccentric portion 143. Since the first eccentric portion 142 and the second eccentric portion 143 are offset from each other, the first planetary gear 132 and the second planetary gear 133 are eccentric relative to the shaft tube portion 141.

Please refer to FIG. 5. According to the description of the embodiment, the first planetary gear 132 and the second planetary gear 133 are offset relative to each other, so that the first planetary gear 132 and the second planetary gear 133 are installed in the gear ring 131. The engagement phase difference between the two planetary gears 132 and 133 and the gear ring 131 is preferably 180 degrees. Secondly, each tooth shape of the inner tooth structure of the gear ring 131 can be a skew tooth shape or a cycloid tooth shape, and each tooth shape of the outer tooth structure of the planetary gears 132 and 133 is a skew tooth shape or a cycloid tooth shape relative to the inner tooth structure. When the planetary gears 132 and 133 rotate, the bushing 136a and the through holes 132b and 133b produce rolling contact, and then the bushing 136a and the shaft sleeve 136b can rotate relative to each other to form a rotational fit.

Please refer to FIG. 1 again. The electric drive device 120 provides a rotation torque, and the rotor 122 drives the eccentric shaft 140 to rotate. Since there is a gap 200 between the axial inner portion of the eccentric shaft 140 and the crankshaft 150 and the supporting rolling element 185 is coupled, the driving force of the electric drive device 120 is not transmitted to the crankshaft 150. Secondly, the two eccentric parts 142 and 143 of the eccentric shaft 140 respectively drive the two planetary gears 132 and 133 to perform eccentric orbital motion in the gear ring 131, thereby driving the first planetary bracket 134 and the second planetary bracket 135, wherein the actuating torque of the second planetary bracket 135 is transmitted to the chain output shaft 160 through the first clutch 171.

The crankshaft 150 rotates under the pedaling force of the crank. Since there is a gap 200 between the axial inner part of the eccentric shaft 140 and the crankshaft 150 and the supporting rolling element 185 is coupled, the force of the crankshaft 150 is not transmitted to the eccentric shaft 140. Secondly, the pedaling force borne by the crankshaft 150 is transmitted to the chain output shaft 160 through the second clutch 172.

In the structural configuration of this embodiment, the chain output shaft 160 bears the output torque from the electric drive device 120 and the crankshaft 150 respectively or jointly through the first clutch 171 and the second clutch 172. Secondly, the gear mechanism 130 can still achieve the expected driving effect by using one planetary gear 132 or 133, but the structure in which the engagement phase difference between the two planetary gears 132, 133 and the gear ring 131 is 180 degrees can make the revolution formed by the two planetary gears 132, 133 and the rotation of the two planetary brackets 134, 135 driven by the two planetary gears 132, 133 achieve a more stable rotation effect. Furthermore, the two planetary supports 134 and 135 of this embodiment are located on opposite sides of the gear mechanism 130. This structural form not only makes the entire gear mechanism 130 have high structural rigidity, but also can provide a more balanced and stable operation effect when the gear mechanism 130 is in operation.

In the present embodiment, the crankshaft 150 is inserted into the axial inner part of the eccentric shaft 140, and the gap 200 is directly formed between the axial inner part of the eccentric shaft 140 and the crankshaft 150, so that the crankshaft 150 that bears the pedaling force and the eccentric shaft 140 that bears the electric drive force can form a coaxial combined structure to achieve the effect of simplifying the structure and reducing the volume, and can also reduce the number of supporting rolling elements to be installed, thereby reducing the rotational interference between the eccentric shaft 140 and the crankshaft 150. Secondly, the deformable bearing bracket 180 and the speed detector 190 are installed in the housing 110 and coupled to the chain output shaft 160 and the crank shaft 150, so that the volume of the overall mid-mounted motor 100 can be further miniaturized.

The mid-mounted motor 100 disclosed in this embodiment can be applied to an electric assist bicycle, and the contents disclosed in the embodiment are the preferred embodiments and design diagrams of the present invention, but the preferred embodiments and design diagrams are only examples for illustration and are not used to limit the scope of rights of the present invention. Any implementation by equal technical means or within the scope of rights covered by the following "Scope of Patent Application" does not deviate from the scope of the present invention and is the scope of rights of the applicant.

100: Mid-mounted motor

110: Shell

111: First shell

112: Second shell

120: Electric drive device

121: Stator

122: Rotor

130: Gear mechanism

131:Ring

132: First planetary gear

133: Second planetary gear

134: First planetary bracket

135: Second planetary bracket

140: Eccentric shaft

141: Axle tube part

142: First eccentric part

143: Second eccentric part

150: Crankshaft

160: Chain output shaft

171: First clutch

172: Second clutch

180: Deformed bearing bracket

180a: Strain gauge

181: Supporting rolling element

182, 183, 184, 185, 186, 187: Supporting rolling elements

190: Speed detector

200: Gap

Claims (10)

A mid-mounted motor is used to transmit an electric drive force and a pedaling force to a gear disc, which includes: a gear mechanism installed in a housing, including at least one planetary gear engaged in a gear ring, two planetary brackets located at two opposite sides of the planetary gear, and a plurality of locking members used to lock the two opposite planetary brackets and pass through the planetary gear; an eccentric shaft including At least one eccentric portion is formed at one end of a shaft tube portion, the eccentric portion is offset relative to the shaft tube portion, and the eccentric portion is used to extend into the gear mechanism to couple the planetary gear; an electric drive device has a rotatable rotor and is fixedly connected to a portion of the shaft tube portion of the eccentric shaft; a crankshaft is inserted into the axial inner part of the eccentric shaft and is matched with a supporting rolling element to couple the eccentric shaft to the eccentric shaft. a center portion; a gap formed between the inner wall surface of the shaft tube portion of the eccentric shaft and the outer surface of the crank shaft; a chain output shaft coupled to the gear mechanism through a first clutch and coupled to the crank shaft through a second clutch, the chain output shaft combined with the gear; a torque detector, including a deformable bearing bracket coupled to the chain output shaft through a bearing, and the deformable bearing bracket is fixedly connected to the crankshaft; In the housing; wherein the rotor drives the eccentric shaft and the planetary gear to rotate, and the planetary gear revolves eccentrically in the gear ring, thereby driving the two planetary brackets to rotate and transmitting the driving force to the chain output shaft through the first clutch; the rotational force of the crankshaft is transmitted to the chain output shaft through the second clutch; the torque detector is used to detect the torque on the chain output shaft. The intermediate motor as described in claim 1, wherein the number of the planetary gears of the gear mechanism is two, including a first planetary gear and a second planetary gear, the number of the eccentric parts of the eccentric shaft is two, including a first eccentric part and a second eccentric part, the first planetary gear is coupled to the first eccentric part, the second planetary gear is coupled to the second eccentric part, the number of teeth of the first planetary gear and the second planetary gear is less than the number of teeth of the gear ring, and the phase difference of the engagement position of the first planetary gear and the second planetary gear engaging with the gear ring is 180 degrees. The intermediate motor as described in claim 1, wherein the first clutch and the second clutch are overrunning clutches. The intermediate motor as described in claim 1, wherein the first clutch and the second clutch are pawl clutches. The intermediate motor as described in claim 1 or 2, wherein the planetary gear has a plurality of through holes, and each through hole is provided with a combination of a sleeve inserted in a bushing, the outer diameter of the bushing is smaller than the inner diameter of the through hole, and the locking member locks the two planetary brackets and the sleeve passing through the through hole of the planetary gear. The intermediate motor as described in claim 5, wherein the bushing forms a rotational fit with the shaft sleeve, and the shaft sleeve forms a loose fit with the locking member. The intermediate motor as described in claim 1, wherein the electric drive device includes a stator fixed to the housing, and the rotor is located at the center of the stator. The intermediate motor as described in claim 1 further includes a speed detector coupled to the crankshaft and corresponding to the electric drive device. The intermediate motor as described in claim 1, wherein the gear ring has an inner tooth structure, and each tooth shape of the inner tooth structure can be a splayed tooth shape, and the planetary gear has an outer tooth structure, and each tooth shape of the outer tooth structure is a splayed tooth shape. The intermediate motor as described in claim 1, wherein the gear ring has an inner gear structure, and each tooth shape of the inner gear structure can be a cycloid tooth shape, and the planetary gear has an outer gear structure, and each tooth shape of the outer gear structure is a cycloid tooth shape.

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