Drive unit for an electrically assisted bicycle and electrically assisted bicycle

Abstract

A drive unit for an electrically connected bicycle, in which a housing and a rotatable shaft include metal materials different from each other; an outer peripheral portion of a dust seal is in contact with an inner peripheral portion of an opening of the housing, the opening allowing the rotatable shaft to pass therethrough; an outer end, in a rotational axis direction of the rotatable shaft, of the inner peripheral portion of the opening of the housing has a chamfered portion whose diameter increases toward an outer side of the opening; the dust seal has a first lip covering the chamfered portion; and the dust seal does not protrude outward in the rotational axis direction to an outermost portion of the opening in the rotational axis direction.

Description

[0001] The present invention relates to a drive unit for an electrically assisted bicycle and the electrically assisted bicycle.

[0002] Bicycles are widely used as an easy-to-use means of transportation by a variety of people, regardless of age or gender. Recently, electric-assisted bicycles, in which the user's pedaling power is supported by electric motors, have become increasingly popular (see, for example, JP 2007-230411 A).

[0003] Such an electric motor is supplied with electrical energy from a battery mounted on the vehicle, i.e., the electrically assisted bicycle, and thus generates drive power. The electrically assisted bicycle causes the electric motor to generate drive power equivalent to the force of a human body, namely the force a user exerts on the pedals, thus relieving the user's strain when, for example, riding uphill or carrying a load.

[0004] A drive unit of an electrically assisted bicycle includes a housing housing an electric motor and a rotating shaft partially exposed on the outside of the housing. A crank arm, for example, is attached to the rotating shaft.

[0005] In the case where the housing and the rotary shaft contain metal materials that are different from each other, there is a problem that if water accumulates between an opening of the housing and the rotary shaft, electrolytic corrosion (galvanic corrosion) is likely to occur.

[0006] The object of the present invention is to provide a drive unit for an electrically assisted bicycle wherein electrolytic corrosion of the drive unit is suppressed. According to the present invention, this object is achieved by a drive unit for an electrically assisted bicycle having the features of independent claim 1. Preferred embodiments are set forth in the dependent claims.

[0007] This specification discloses a drive unit and an electrically assisted bicycle, which are described in the following points. [Point 1]

[0008] A drive unit for an electrically assisted bicycle 1, the drive unit comprising: an electric motor; a housing that houses the electric motor; a rotatable shaft rotatably supported by the housing and partially exposed on the outside of the housing; and an annular dust seal provided between the rotating shaft and the housing, the dust seal prevents dust from entering the housing from the outside, where: the housing and the rotating shaft contain metal materials that are different from each other, an inner peripheral portion of the dust seal is in sliding contact with the rotatable shaft, an outer peripheral portion of the dust seal is in contact with an inner peripheral portion of an opening of the housing, the opening allowing the passage of the rotatable shaft, an outer end, in the rotational axis direction of the rotatable shaft, of the inner peripheral portion of the opening of the housing includes a chamfered portion having a diameter thereof increasing toward the outside of the opening, the dust seal includes a first lip covering the beveled portion, and the dust seal does not protrude outwards in the direction of rotation axis beyond an outermost portion of the opening in the direction of rotation axis.

[0009] In the case where the housing and the rotary shaft contain metal materials that are different from each other, if water accumulates between the opening of the housing and the rotary shaft, electrolytic corrosion (galvanic corrosion) easily occurs. Electrolytic corrosion can be suppressed to some extent by painting the opening. However, there are cases where the painting is not satisfactorily applied to the opening. For example, in the case where the projection provided on the opening is thin, the painting is not satisfactorily applied to the projection. According to one embodiment of the present invention, the dust seal includes a first lip that covers the tapered portion of the opening.The first lip covers the chamfered portion so that electrolytic corrosion can be suppressed even if the paint is not applied satisfactorily to the opening.

[0010] According to one embodiment of the present invention, the dust seal does not protrude to the outermost portion of the opening in the rotation axis direction. With this arrangement, the size of the drive unit can be reduced in the width direction.

[0011] The crank arms can be attached to the rotating shaft. If the dust seal protrudes beyond the opening of the housing, it may interfere with the crank arms or the like. Since the dust seal does not protrude beyond the opening in this design, interference with the dust seal by the crank arms can be suppressed. [Point 2]

[0012] The drive unit of item 1, wherein the first lip of the dust seal is shaped to extend away from the rotatable shaft while extending outward in the rotation axis direction.

[0013] With this arrangement, the beveled section of the opening can be covered in a suitable manner. [Point 3]

[0014] The drive unit of point 1 or 2, where: a groove is provided in the inner peripheral portion of the opening in a circumferential direction of the opening, and the outer peripheral portion of the dust seal includes a second lip fitted into the groove.

[0015] Since the second lip of the dust seal is fitted into the groove of the opening, the dust seal can be attached to the housing. [Point 4]

[0016] The drive unit of point 3, where: the opening has a projection which acts as an outer wall of the grooves in the direction of the axis of rotation, and the beveled portion is provided on the projection.

[0017] Even if the paint is not applied satisfactorily to the opening, the first lip covers the chamfered portion, so that electrolytic corrosion can be suppressed. [Point 5]

[0018] The drive unit of item 3 or 4, with the second lip of the dust seal snapped into the groove.

[0019] The dust seal can be attached to the case with a snap-on closure. It also better prevents water and dust from entering the case. [Point 6]

[0020] The drive unit of item 4, wherein the first lip and the second lip of the dust seal hold the projection therebetween by an elastic force.

[0021] With this arrangement, a gap is less likely to form between the first lip and the chamfered portion, so electrolytic corrosion can be more effectively suppressed. Furthermore, the intrusion of water and dust into the interior of the housing can be more effectively suppressed. [Point 7]

[0022] The drive unit from point 1 or 2, with the dust seal pressed into the opening.

[0023] The dust seal is pressed into the opening and can therefore be attached to the housing. [Point 8]

[0024] The drive unit of any one of items 1 to 7, wherein the inner peripheral portion of the dust seal includes a sealing lip in sliding contact with the rotatable shaft.

[0025] With this arrangement, the flow of oil from the inside to the outside of the case and the intrusion of water and dust from the outside into the inside of the case can be suppressed. [Point 9]

[0026] The drive unit of item 8, wherein the inner peripheral portion of the dust seal further includes a dust lip that is in sliding contact with the rotatable shaft and is arranged outside the seal lip in the rotation axis direction.

[0027] This arrangement prevents dust from outside from entering the interior of the housing. [Point 10]

[0028] The drive unit of any one of items 1 to 9, wherein the housing includes a metal material containing magnesium as a main component.

[0029] This arrangement allows the weight of the drive unit to be reduced. [Point 11]

[0030] The drive unit of any one of items 1 to 10, wherein the rotatable shaft includes a metal material containing iron as a main component.

[0031] With this arrangement, the degree of rigidity and strength required for the rotating shaft can be achieved at low cost. [Point 12]

[0032] An electrically assisted bicycle incorporating the drive unit of any of items 1 to 11.

[0033] With this arrangement, the electrically assisted bicycle including the drive unit, which is highly resistant to water and compact, can be realized.

[0034] When the housing and the rotary shaft of the drive unit contain metallic materials that are different from each other, electrolytic corrosion (galvanic corrosion) easily occurs when water accumulates between the opening of the housing and the rotary shaft. Electrolytic corrosion can be suppressed to some extent by painting the opening. However, there are cases where the painting is not satisfactorily applied to the opening. For example, if the projection provided on the opening is thin, the painting is not satisfactorily applied to the projection. According to one embodiment of the present invention, the dust seal includes a first lip that covers the tapered portion of the opening.The first lip covers the chamfered portion so that electrolytic corrosion can be suppressed even if the paint is not applied satisfactorily to the opening.

[0035] According to one embodiment of the present invention, the dust seal does not protrude to the outermost portion of the opening in the direction of the rotation axis. This arrangement allows the size of the drive unit to be reduced in the width direction.

[0036] The crank arms can be attached to the rotating shaft. If the dust seal protrudes beyond the opening of the housing, it may interfere with the crank arms or the like. Since the dust seal does not protrude beyond the opening in this design, interference with the dust seal by the crank arms can be suppressed. Brief description of the drawings Fig. 1 is a right side view showing an electrically assisted bicycle 1 according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing an example of the internal structure of a drive unit 20 according to an embodiment of the present invention. Fig. 3 is a cross-sectional view showing a portion of a housing 21 according to an embodiment of the present invention. Fig. 4 is a cross-sectional view showing an opening 261 of the housing 21 and a rotatable shaft 30 passing through the opening 261 according to an embodiment of the present invention. Fig. 5 is a perspective view showing a dust seal 60 cut along a plane parallel to a direction D1 of the rotation axis according to an embodiment of the present invention. Fig. 6 is a partially enlarged cross-sectional view of the drive unit 20 according to an embodiment of the present invention. Fig. 7 is a partially enlarged cross-sectional view of the drive unit 20 according to an embodiment of the present invention. Fig. 8 is a cross-sectional view showing the positional relationship between the opening 261 of the housing 21 and the dust seal 60 in the direction D1 of the rotation axis according to an embodiment of the present invention. Fig. 9 is a cross-sectional view showing the dust seal 60 in a state where it is fixed to an inner peripheral portion 262 of the opening 261 by press fitting according to an embodiment of the present invention. Detailed description

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the embodiment, like elements are denoted by like reference numerals, and overlapping descriptions are omitted. In the drawings, letters F, Re, L, R, U, and D represent front, rear, left, right, up, and down, respectively. The "front-back," "left-right," and "up-down" directions with respect to an electric-assisted bicycle respectively denote the front-back, left-right, and up-down directions for a user sitting on a seat (saddle) of the electric-assisted bicycle and facing a handlebar. The following embodiment is merely illustrative and does not limit the present invention in any way. [electrically assisted bicycle]

[0038] Fig. 1 is a right side view of an electrically assisted bicycle 1 according to an embodiment of the present invention.

[0039] The electric-assisted bicycle 1 includes a body frame 2 extending in a front-to-back direction. The body frame 2 includes a head tube 11, a down tube 12, a top tube 14, a seat tube 16, a chainstay 18, a seat stay 19, and a bracket 26. The head tube 11 is located at a front end of the body frame 2. A steering column 13 is rotatably inserted into the head tube 11. A handlebar 4 is fixed to the steering column 13. A display unit 5 that displays various information about the electric-assisted bicycle 1 is attached to the handlebar 4. A main light 59 is attached in front of the handlebar 4.

[0040] A front fork 15 is attached to a lower end of the steering column 13. A lower end of the front fork 15 supports a front wheel 6, which is a steering wheel, so that the front wheel 6 is rotatable.

[0041] The down tube 12 extends obliquely rearward and downward from the head tube 11. The seat tube 16 extends upward from a rear end of the down tube 12. The chainstay 18 extends rearward from a lower end of the seat tube 16. The bracket 26 connects the rear end of the down tube 12, the lower end of the seat tube 16, and a front end of the chainstay 18. The top tube 14 is provided so that it connects an upper portion of the head tube 11 and an upper portion of the seat tube 16. A seat post 17 is inserted into the seat tube 16. The saddle 3, on which the user can sit, is provided at an upper end of the seat post 17.

[0042] A rear end of the chainstay 18 supports a rear wheel 7, which is a drive wheel, so that the rear wheel 7 is rotatable. The seat stay 19 extends obliquely rearward and downward from the upper portion of the seat tube 16. A lower end of the seat stay 19 is connected to the rear end of the chainstay 18. A gear 58 that changes the gear ratio is provided at the rear end of the chainstay 18. The gear 58 may be arranged near a pedal crankshaft 22. A speed sensor 55 that detects the rotational speed of the rear wheel 7 is provided at a rear portion of the chainstay 18. The speed sensor 55 may be attached to a lower portion of the front fork 15 to detect the rotational speed of the front wheel 6.

[0043] A drive unit 20 is provided on the bracket 26, which is located near a position in the body frame 2 that represents the center of the vehicle (i.e., the electrically assisted bicycle 1). A housing 21 ( Fig. 2) the drive unit 20 includes an electric motor 25, an MCU (engine control unit), a deceleration device 24 ( Fig. 2) and the like. The pedal crankshaft 22 is supported by passing through the drive unit 20 in a left-right direction. Crank arms 35 are provided at both ends of the pedal crankshaft 22. The pedals 37 are rotatably supported at the tips of the crank arms 35, respectively.

[0044] A battery unit 56, which supplies electrical power to the drive unit 20 or the like, is attached to the down tube 12. In the example shown in Fig. 1, the battery unit 56 is disposed inside the down tube 12. The down tube 12 may be hollow. At least a portion of the down tube 12 may have a U-shaped cross-section, and the down tube 12 may be provided with a cover that covers the U-shaped portion.

[0045] The battery unit 56 may be disposed on an outer surface of the down tube 12. The battery unit 56 may be attached to the bracket 26 or to the seat tube 16. The battery unit 56 may be removable from the electrically assisted bicycle 1.

[0046] The battery unit 56 contains a battery and a BMS (battery management system). The battery is a rechargeable battery. The BMS controls the charging / discharging of the battery and monitors an output current, remaining battery capacity, and the like.

[0047] The MCU of the drive unit 20 controls the operation of the electric motor 25 and also controls the operation of various components of the electrically assisted bicycle 1. The MCU includes a semiconductor integrated circuit, such as a processor or the like, and a motor control circuit. Rotation of the pedal crankshaft 22 generated by the user's pedaling on the pedals 37 is transmitted to the rear wheel 7 via a drive sprocket 34 and a chain 53. The MCU controls the electric motor 25 to generate a drive-assist output corresponding to a rotational output of the pedal crankshaft 22 generated by the user's pedaling on the pedals 37. The assist power generated by the electric motor 25 is transmitted to the rear wheel 7 via the drive sprocket 34 and the chain 53. Instead of the chain 53, a belt, a shaft, or the like may also be used. [Drive unit]

[0048] With reference to Fig. 2 describes an example of the configuration of the drive unit 20. Fig. 2 is a cross-sectional view showing an example of the internal structure of the drive unit 20.

[0049] As in Fig. 2, the drive unit 20 includes the housing 21, a rotatable shaft 30, a transmission mechanism 40 and the electric motor 25.

[0050] First, the structure of the housing 21 according to the present embodiment will be described.

[0051] The housing 21 is secured to the bracket 26 by a plurality of fastening elements (see Fig. 1). The housing 21 includes a first housing 211, a second housing 212, and a cover 213. The housing 21 is formed, for example, from a metal material containing magnesium as a main component (magnesium alloy). Using a metal material containing magnesium as a main component can reduce the weight of the drive unit 20.

[0052] The first housing 211 is stacked on the second housing 212 in a left-to-right direction, more specifically, from the left. The first box 211 and the second box 212 are secured together by a plurality of connecting elements. This creates a gap 214 between the first housing 211 and the second housing 212.

[0053] The cover 213 is placed on the first housing 211 in a left-to-right direction, more specifically, from the left. The cover 213 and the first housing 211 are secured together by a plurality of fasteners. This creates a space 215, which is covered by the cover 213, to the left of the first housing 211. The electric motor 25 is housed in the space 215.

[0054] A configuration of the rotary shaft 30 according to this embodiment will now be described. The rotary shaft 30 includes the pedal crankshaft 22 and a rotation shaft 23.

[0055] The rotatable shaft 30 extends through the housing 21 in the left-right direction of the vehicle and is rotatably mounted in the housing 21.

[0056] Fig. 3 is a cross-sectional view showing a portion of the housing 21. An opening 261 is provided in the first housing 211 of the housing 21. An opening 281 is provided in the second housing 212. The opening 261 and the opening 281 are each cylindrical. The rotatable shaft 30 passes through the opening 261 and the opening 281, so that a portion of the rotatable shaft 30 is exposed to the outside of the housing 21.

[0057] A central axis line CL4 of the pedal crankshaft 22 extends in the left-right direction. Viewed in an axial direction (thrust direction) of the pedal crankshaft 22, the central axis line CL4 is a rotational central axis RC4 (fourth central axis) of the pedal crankshaft 22. The pedal crankshaft 22 rotates around the central axis line CL4 with respect to the housing 21. The rotational central axis RC4 is the rotational axis of the rotary shaft 30.

[0058] The rotatable shaft 30, which includes the pedal crankshaft 22, extends through the housing 21 along the fourth central axis RC4 and is supported by the housing 21 so as to be rotatable about the fourth central axis RC4. The pedal crankshaft 22 is rotatably supported by a pair of bearings 38L and 38R within the housing 21. The bearing 38L is located on the left side in the axial direction and is fixed to the first housing 211. The bearing 38R is located on the right side in the axial direction and is fixed to the second housing 212.

[0059] The pedal crankshaft 22 is arranged to pass through the rotary shaft 23. The rotary shaft 23 is housed in the housing 21. The rotary shaft 23 will be described in more detail below. The pair, more specifically the left and right crank arms 35 ( Fig. 1), are attached to the pedal crankshaft 22. The pedals 37 ( Fig. 1) are each attached to the crank arms 35.

[0060] The pedal crankshaft 22 includes a metal material containing iron as a main component, such as carbon steel, alloy steel, or the like. Using such a metal material containing iron as a main component can realize the degree of rigidity and strength required for the pedal crankshaft 22 at a low cost.

[0061] Now, a configuration of the electric motor 25 and the transmission mechanism 40 according to this embodiment will be described.

[0062] The electric motor 25 is housed in the housing 21 and secured to the housing 21. The electric motor 25 generates drive power to operate the electrically assisted bicycle 1. The electric motor 25 includes a stator 251 and a rotor 252.

[0063] The stator 251 includes a plurality of coil formers 2512, around each of which a coil 2511 is wound. An iron core 2513 is inserted into each of the coil formers 2512.

[0064] The stator 251 is located in the space 215. In this state, the stator 251 is fixed to the first housing 211.

[0065] The rotor 252 is located inside the stator 251. A central axis line CL1 of the rotor 252 is parallel to the central axis line CL4 of the pedal crankshaft 22. That is, the rotor 252 is arranged to be parallel to the pedal crankshaft 22. Viewed in the axial direction of the pedal crankshaft 22, the central axis line CL1 is a rotational central axis RC1 (first central axis) of the rotor 252.

[0066] The rotor 252 includes a rotor main body 2521 and an output shaft 2522. An outer peripheral surface of the rotor main body 2521 is alternately magnetized with N poles and S poles.

[0067] The output shaft 2522 is arranged to pass through the rotor main body 2521. The output shaft 2522 is secured to the rotor main body 2521. That is, the output shaft 2522 is rotated together with the rotor main body 2521.

[0068] The output shaft 2522 is supported in the housing 21 so as to be rotatable about the first central axis RC1 within the housing 21. The output shaft 2522 is supported by two bearings 42L and 42R so as to be rotatable about the central axis line CL1 with respect to the housing 21. The bearing 42L is secured to the cover 213. The bearing 42R is located on the right side of the rotor main body 2521 and is secured to the first housing 211. The output shaft 2522 is arranged to pass through the first housing 211. An output gear 252A is formed in a right portion of the output shaft 2522. The output gear 252A is, for example, a helical gear.

[0069] The transmission mechanism 40 is housed in the housing 21. Specifically, the transmission mechanism 40 is located in the space 214. The transmission mechanism 40 includes the deceleration device 24, an idle gear 41, and a rotating shaft 43. The transmission mechanism 40 transmits torque from the electric motor 25 to the rotating shaft 23.

[0070] The deceleration device 24 is rotatably supported in the housing 21 and increases the torque of the output gear 252A of the electric motor 25. The deceleration device 24 includes a first transmission gear 241, a second transmission gear 242, and a transmission shaft 243. A central axis line CL2 of the transmission shaft 243 is parallel to the central axis line CL4 of the pedal crankshaft 22. That is, the transmission shaft 243 extends parallel to the central axis line CL4 of the pedal crankshaft 22. Viewed in the axial direction of the transmission shaft 243, that is, in the axial direction of the pedal crankshaft 22, the central axis line CL2 is a rotational central axis RC2 (second central axis) of the transmission shaft 243. The deceleration device 24 is supported in the housing 21 so as to be rotatable about the second central axis RC2.

[0071] The first transmission gear 241 is located on a right portion, in the axial direction, of the transmission shaft 243. A left portion of the transmission shaft 243 is rotatably supported by the bearing 44L. The first transmission gear 241, located on the right portion of the transmission shaft 243, is rotatably supported by the bearing 44R. The transmission shaft 243 and the first transmission gear 241 are supported by the two bearings 44L and 44R so that they are rotatable about the central axis line CL2. The bearing 44L is secured to the first housing 211. The bearing 44R is secured to the second housing 212.

[0072] The first transmission gear 241 is engaged with the output gear 252A of the electric motor 25. With this arrangement, the drive power generated by the electric motor 25 is transmitted from the output gear 252A to the first transmission gear 241.

[0073] A one-way clutch 244 is arranged between the first transmission gear 241 and the transmission shaft 243. The one-way clutch 244 couples the transmission shaft 243 and the first transmission gear 241 to each other. The one-way clutch 244 restricts the rotation of the first transmission gear 241 in one direction with respect to the transmission shaft 243. A rotational force of the output gear 252A in a direction in which the rear wheel 7 (see Fig. 1) of the electrically assisted bicycle 1 is rotated forward is transmitted to the transmission shaft 243 via the first transmission gear 241, while a rotational force of the output gear 252A in a direction in which the rear wheel 7 is rotated rearward is not transmitted to the transmission shaft 243. The one-way clutch 244 prevents the rotational force of forward rotation of the pedal crankshaft 22, which is generated by the human power of the rider (i.e., the user), from being transmitted to the electric motor 25.

[0074] The first transmission gear 241 has a larger diameter than the output gear 252A of the electric motor 25 and a larger number of teeth than the output gear 252A. That is, the first transmission gear 241 is decelerated more than the output gear 252A.

[0075] The second transmission gear 242 is formed of a metallic material (for example, iron). The second transmission gear 242 is located on the transmission shaft 243. The second transmission gear 242 is located at a different position than the first transmission gear 241 in the axial direction of the transmission shaft 243. The second transmission gear 242 has a smaller diameter than the first transmission gear 241 and a smaller number of teeth than the first transmission gear 241. The transmission shaft 243 and the second transmission gear 242 are integrally formed with each other in this embodiment, but are not limited thereto. The second transmission gear 242 may be splined (or press-fitted) to the transmission shaft 243. The second transmission gear 242 rotates together with the transmission shaft 243.The transmission shaft 243 transmits the rotational movement of the first transmission gear 241 to the second transmission gear 242.

[0076] The idle gear 41 is formed of a metallic material (e.g., iron). The idle gear 41 is located on the transmission shaft 243. The idle gear 41 is fixed to the rotating shaft 43, for example, by a fastener, but not limited thereto. The idle gear 41 may be splined (or press-fitted) to the transmission shaft 243. The idle gear 41 and the rotating shaft 43 may be integrally formed with each other. The idle gear 41 rotates together with the transmission shaft 243.

[0077] A central axis line CL3 of the rotating shaft 43 is parallel to the central axis line CL4 of the pedal crankshaft 22. That is, the rotating shaft 43 extends parallel to the central axis line CL4 of the pedal crankshaft 22. Viewed in the axial direction of the rotating shaft 43, that is, in the axial direction of the pedal crankshaft 22, the central axis line CL3 is a rotational central axis RC3 (third central axis) of the rotating shaft 43. The idler gear 41 fixed to the rotating shaft 43 is supported by the housing 21 so as to be rotatable about the third central axis RC3 within the housing 21.

[0078] The rotating shaft 43 is supported by two bearings 46L and 46R so that it can rotate around the central axis line CL3. The bearings 46L and 46R are secured to the first housing 211. The idle gear 41 is located closer to the bearing 46R than to the bearing 46L in the axial direction of the rotating shaft 43. The idle gear 41 is engaged with the second transmission gear 242 of the deceleration device 24. With this arrangement, the output torque of the electric motor 25, which is increased by the deceleration device 24, is transmitted to the idle gear 41.

[0079] Now, a configuration of the pedal crankshaft 22 and its surroundings will be described.

[0080] The rotary shaft 23 is arranged coaxially with the pedal crankshaft 22 and is rotatable together with the pedal crankshaft 22. The rotary shaft 23 includes a coupling shaft 231 and a one-way clutch 50.

[0081] The coupling shaft 231 is cylindrical. The pedal crankshaft 22 is inserted into the coupling shaft 231. The coupling shaft 231 is arranged coaxially with the pedal crankshaft 22.

[0082] A left end of the coupling shaft 231 is coupled to the pedal crankshaft 22 through a spline or the like. As a result, regardless of whether the pedal crankshaft 22 is rotated forward or backward, the coupling shaft 231 rotates together with the pedal crankshaft 22.

[0083] A torque detector 232 is arranged around the coupling shaft 231. The torque detector 232 is supported by the coupling shaft 231 and is non-rotatable with respect to the first housing 211. The torque detector 232 detects a torque generated on the coupling shaft 231 when the rider pedals. The torque detector 232 is, for example, a torque sensor of a magnetostriction system. The torque detector 232 outputs a signal corresponding to the detected torque to the MCU mounted on a circuit substrate 110. The MCU refers to the torque detected by the torque detector 232 to detect the state of the pedaling motion performed by the rider, thus controlling the electric motor 25.An external connector 130 is a connector for electrically connecting the drive unit 20 and an external device (for example, the battery unit 56, the display unit 5, or the like).

[0084] The one-way clutch 50 is located to the right of the torque detector 232 in the axial direction of the pedal crankshaft 22. The one-way clutch 50 is provided on the pedal crankshaft 22 via the coupling shaft 231. The one-way clutch 50 is arranged coaxially with the pedal crankshaft 22. The one-way clutch 50 includes an inner member 51 and an outer member 52.

[0085] The inner member 51 of the one-way clutch 50 is cylindrical. A right portion of the coupling shaft 231 is inserted into the inner member 51. The inner member 51 is arranged coaxially with the coupling shaft 231. In this state, the right portion of the coupling shaft 231 is coupled to the inner member 51 by splines or the like. As a result, regardless of whether the coupling shaft 231 is rotated forward or backward, the inner member 51 is rotated together with the coupling shaft 231. That is, regardless of whether the pedal crankshaft 22 is rotated forward or backward, the inner member 51 is rotated together with the pedal crankshaft 22. The coupling shaft 231 and the inner member 51 cooperate as a crank rotation input shaft that is integrally rotatable with the pedal crankshaft 22.

[0086] The outer member 52 of the one-way clutch 50 is cylindrical. The pedal crankshaft 22 is inserted into the outer member 52. A plain bearing 49 is arranged between the outer member 52 and the pedal crankshaft 22. In this arrangement, the outer member 52 is arranged coaxially with the pedal crankshaft 22 and is rotatable.

[0087] A ratchet mechanism as a one-way clutch mechanism is formed between the outer member 52 and the inner member 51. With this arrangement, the rotational force in the forward rotation direction of the inner member 51 is transmitted to the outer member 52, while the rotational force in the reverse rotation direction of the inner member 51 is not transmitted to the outer member 52. The rotational force in the forward rotation direction of the outer member 52 generated by the rotation of the electric motor 25 is not transmitted to the inner member 51.

[0088] The outer member 52 is supported by the bearing 38R so as to be rotatable about the central axis line CL4 of the pedal crankshaft 22 with respect to the housing 21. The outer member 52 is arranged to pass through the second housing 212. The drive sprocket 34 is attached to a portion of the outer member 52 located outside (right) of the housing 21.

[0089] The outer member 52 includes a driven gear 233. The driven gear 233 is connected to the pedal crankshaft 22 via the one-way clutch 50 and the coupling shaft 231. The driven gear 233 is engaged with the idle gear 41. The driven gear 233 has a larger diameter than the second transmission gear 242 and the idle gear 41 and a larger number of teeth than the second transmission gear 242 and the idle gear 241. That is, the rotational speed of the driven gear 233 is lower than the rotational speed of the second transmission gear 242 and the idle gear 41. The idle gear 41 is engaged with the second transmission gear 242 and the output gear 233, so that the output torque of the electric motor 25, which is increased by the deceleration device 24, can be transmitted to the output gear 233 via the single idle gear 41.

[0090] The outer member 52 transmits a resultant force of the human power transmitted to the coupling shaft 231 (power with which pedaling is performed) and the assist drive force of the electric motor 25 to the drive gear 34. The outer member 52 implements a resultant force output shaft 235, which combines the human power supplied via the one-way clutch 50 and the assist drive force supplied via the driven gear 233 and outputs the resultant force. The resultant force output shaft 235 rotates coaxially with the pedal crankshaft 22. The resultant force output shaft 235 is included in the rotating shaft 23. [Dust seal]

[0091] Now, a dust seal according to this embodiment will be described.

[0092] Fig. 4 is a cross-sectional view showing the opening 261 of the housing 21 and the rotatable shaft 30 passing through the opening 261.

[0093] The rotatable shaft 30 is rotatably supported in the housing 21 by the bearing 38L. An outer gear of the bearing 38L is fixed to the housing 21. The bearing 38L is prevented from moving in the direction D1 of the rotation axis of the rotatable shaft 30 by a projection 273 of the housing 21 and the snap rings 39 and 94.

[0094] With respect to the radial direction of the rotatable shaft 30, an annular dust seal 60 is provided between the opening 261 of the housing 21 and the rotatable shaft 30. The dust seal 60 closes a gap between the opening 261 and the rotatable shaft 30 and prevents dust from entering the housing 21 from the outside.

[0095] In this embodiment, the rotatable shaft 30 includes an adapter 92 that adjusts the diameter of the pedal crankshaft 22. The adapter 92 is attached to the pedal crankshaft 22, for example, by press fitting or splining, and enlarges the diameter of a portion of the pedal crankshaft 22. The dust seal 60 is in sliding contact with the adapter 92 of the rotatable shaft 30. The dust seal 60 may be in direct contact with the pedal crankshaft 22 of the rotatable shaft 30.

[0096] Fig. 5 is a perspective view showing the dust seal 60 cut along a plane parallel to the direction D1 of the rotation axis of the rotary shaft 30. Fig. 6 and Fig. 7 are each a partially enlarged cross-sectional view of the drive unit 20 and show a portion enclosed by the dashed line in Fig. 4 is included, in magnification. Fig. 7 omits the dust seal 60. Fig. 6 and Fig. 7 omit the bearing 38L for a better understanding of a feature of this embodiment. In the example shown in Fig. 4, Fig. 6 and Fig. 7, the left side in the direction D1 of the rotation axis of the rotatable shaft 30 is the outside of the housing 21, and the right side in the direction D1 of the rotation axis is the inside of the housing 21. The outside of the housing 21 in the direction D1 of the rotation axis is the outside of the opening 261.

[0097] As in Fig. 5, the dust seal 60 includes a body 61 and a metal ring (reinforcing ring) 67. The body 61 is formed, for example, from an elastomer such as synthetic rubber or the like. The metal ring 67 increases the rigidity of the dust seal 60. With respect to a radial direction of the dust seal 60, a sealing lip 65 and a dust lip 66 are provided in an inner peripheral portion 62 of the dust seal 60. With respect to a radial direction of the dust seal 60, a first lip 71 and a second lip 72 are provided in an outer peripheral portion 63 of the dust seal 60.

[0098] As in Fig. 6, the sealing lip 65 and the dust lip 66 provided in the inner peripheral portion 62 of the dust seal 60 are in sliding contact with the adapter 92 of the rotary shaft 30. The dust lip 66 is located outside the sealing lip 65 in the direction D1 of the rotation axis. The sealing lip 65 and the dust lip 66 suppress the flow of oil from the inside of the housing 21 to the outside of the housing 21 and also prevent the entry of water and dust from the outside of the housing 21 into the inside of the housing 21.

[0099] The first lip 71 and the second lip 72 provided in the outer peripheral portion 63 of the dust seal 60 are in contact with an inner peripheral portion 262 of the opening 261 of the housing 21.

[0100] A groove 271 is provided in the inner peripheral portion 262 of the opening 261 in a circumferential direction of the opening 261. The inner peripheral portion 262 includes a protrusion 272 acting as an outer wall of the groove 271 and the protrusion 273 acting as an inner wall of the groove 271 in the direction D1 of the rotation axis. The protrusion 272 and the protrusion 273 are each shaped to extend from the inner peripheral portion 262 generally toward the rotatable shaft 30.

[0101] A second lip 72 of the dust seal 60 is shaped to extend away from the rotatable shaft 30 with respect to the radial direction of the rotatable shaft 30 and is fitted into the groove 271 of the inner peripheral portion 262 of the opening 261. In this example, the second lip 72 is snap-fitted into the groove 271. The second lip 72 is inserted into the groove 271 so that the dust seal 60 can be fixed to the housing 21. Furthermore, the flow of oil from the inside of the housing 21 to the outside of the housing 21 can be suppressed, and the entry of water and dust from the outside of the housing 21 into the inside of the housing 21 can also be suppressed.

[0102] An outer end 265, in the direction D1 of the rotation axis, of the inner peripheral portion 262 of the opening 261 includes a tapered portion 266 that is tapered in a C-shape or an R-shape. The tapered portion 266 is shaped so that its diameter increases toward an outer side of the opening 261. In this embodiment, the tapered portion 266 is provided on the projection 272.

[0103] The first lip 71 of the dust seal 60 is shaped to extend away from the rotatable shaft 30 with respect to the radial direction of the rotatable shaft 30 while extending outward in the direction D1 of the rotation axis. As shown in Fig. 6, the first lip 71 covers the beveled portion 266 of the opening 261. In this embodiment, the phrase "the first lip 71 covers the beveled portion 266" may mean that the first lip 71 covers a portion of the beveled portion 266 or that the first lip 71 covers the entire beveled portion 266.

[0104] In the case where the housing 21 and the rotary shaft 30 contain metal materials that are different from each other, if water accumulates between the opening 261 of the housing 21 and the rotary shaft 30, electrolytic corrosion (galvanic corrosion) easily occurs. The electrolytic corrosion can be suppressed to some extent by a paint applied to the opening 261. However, in the case where the opening 261 has a certain shape, the paint may not be satisfactorily applied to the opening 261. In the case where, for example, the projection 272 provided at the opening 261 is thin, the paint may not be satisfactorily applied to the projection 272. According to this embodiment, the dust seal 60 includes the first lip 71 covering the tapered portion 266 of the opening 261.The first lip 71 covers the chamfered portion 266 so that electrolytic corrosion can be suppressed even if the paint is not satisfactorily applied to the opening 261.

[0105] The first lip 71 and the second lip 72 of the dust seal 60 hold the projection 272 therebetween by an elastic force. The first lip 71 and the second lip 72 of the dust seal 60 are held in contact with the projection 272 by an elastic force applied by the first and second lips 17 and 72. With this arrangement, a gap is not easily formed between the first lip 71 and the chamfered portion 266, and thus electrolytic corrosion can be more effectively suppressed. Furthermore, the flow of oil from the inside to the outside of the housing 21 can be more effectively suppressed, and the intrusion of water and dust from the outside into the interior of the housing 21 can be more effectively suppressed.

[0106] Now, the positional relationship between the opening 261 of the housing 21 and the dust seal 60 in the direction D1 of the rotation axis will be described.

[0107] Fig. Fig. 8 is a cross-sectional view showing the positional relationship between the opening 261 of the housing 21 and the dust seal 60 in the direction D1 of the rotation axis. In the example shown in Fig. 8, the left side in the direction D1 of the rotation axis is the outside of the housing 21 and the right side in the direction D1 of the rotation axis is the inside of the housing 21. In Fig. 8, a dot-dash line A1 shows the outermost position of the dust seal 60 in the direction D1 of the rotation axis. In Fig. 8, a dashed line A2 shows an outermost portion 267 of the opening 261 of the housing 21.

[0108] In this embodiment, the dust seal 60 does not extend outward in the direction D1 of the rotation axis to the outermost portion 267 of the opening 261. Accordingly, the extension of the dust seal 60 in the direction D1 of the rotation axis of the rotatable shaft 30 is limited to the outermost portion 267. With this arrangement, the size of the drive unit 20 can be reduced in the width direction (left-right direction).

[0109] Components such as the crank arms 35 and the like are fixed to the rotating shaft 30. If the dust seal 60 protrudes outward from the opening 261 of the housing 21, the dust seal 60 may interfere with the crank arms 35 or the like. Since the dust seal 60 does not protrude outward from the opening 261 in this embodiment, interference with the dust seal 60 by the crank arms 35 or the like can be suppressed.

[0110] The first lip 71 of the dust seal 60 covers the tapered portion 266 in such a range that the dust seal 60 does not protrude outward to the outermost portion 267 of the opening 261. As long as the dust seal 60 does not protrude to the outermost portion 267 of the opening 261, the first lip 71 can cover the entire tapered portion 266.

[0111] In the example described above, the dust seal 60 is attached to the inner peripheral portion 262 of the opening 261 by snap-fitting. Alternatively, the dust seal 60 may be attached to the inner peripheral portion 262 by press-fitting.

[0112] Fig. 9 is a cross-sectional view showing the dust seal 60 in a state where it is press-fitted to the inner peripheral portion 262 of the opening 261. In the example shown in Fig. 9, the groove 271 is not provided in the inner peripheral portion 262, and the dust seal 60 is fixed to the inner peripheral portion 262 by press fitting.

[0113] The outer end 265, in the direction D1 of the rotation axis, of the inner peripheral portion 262 includes the chamfered portion 266. The first lip 71 of the dust seal 60 covers the chamfered portion 266 of the opening 261. With this arrangement, electrolytic corrosion can be suppressed.

[0114] In the embodiment described above, the drive unit 20 ( Fig. 2) Four shafts, specifically, the output shaft 2522, the transmission shaft 243, the rotary shaft 43, and the rotatable shaft 30. The number of shafts is not limited to four. The present teaching is applicable to a drive unit having five or more shafts. For example, the present teaching is applicable to a drive unit in which a gear is interposed between the output gear 252A of the electric motor 25 and the first transmission gear 241 of the deceleration device 24, and torque is transmitted from the output gear 252A to the first transmission gear 241 via such a gear.

[0115] In the embodiment described above, the drive unit 20 includes the idle gear 41. The present teaching is applicable to the drive unit 20 without the idle gear 41.

[0116] In the embodiment described above, the entire electric motor 25 is housed in the housing 21. The configuration of the housing 21 is not limited thereto. Only a portion of the electric motor 25 may be housed in the housing 21. For example, an opening through which the electric motor 25 can pass is provided in a left portion of the first housing 211, and the electric motor 25 may be mounted so that its portion is located inside the housing 21 through the opening. In this case, the opening may be provided with a cover to prevent the intrusion of dust and water.

[0117] The cover 213 ( Fig.2) may be a portion of the housing 21 and may be integrated into the housing 21. The cover 213 may be shaped to cover a side surface of the electric motor 25, and the electric motor 25 may be supported by the cover 213. An embodiment in which the electric motor 25 is supported by the cover 213 belongs to an embodiment in which the electric motor 25 is supported by the housing 21.

[0118] In the embodiment described above, the present teaching is applied to the electrically assisted bicycle 1, which is a two-wheeled vehicle. Alternatively, the present teaching is applicable to a three-wheeled electrically assisted vehicle.

[0119] In the embodiment described above, the drive wheel, to which the human body power generated by the rider's pedaling and the assist power generated by the electric motor are transmitted, is the rear wheel. Alternatively, the human body power and the assist power may be transmitted to the front wheel or to both the front and rear wheels, depending on the configuration of the electric-assisted bicycle. The present teachings can be applied to an electric-assisted bicycle having a hub motor on the front wheel.

[0120] An exemplary embodiment of the present teachings is described above. This specification discloses a drive unit and an electrically assisted bicycle described in the following points. [Point 1]

[0121] A drive unit 20 for an electrically assisted bicycle 1, the drive unit 20 comprising: an electric motor 25; a housing 21 which accommodates the electric motor 25; a rotatable shaft 30 which is rotatably supported by the housing 21 and partially exposed on the outside of the housing 21; and an annular dust seal 60 provided between the rotatable shaft 30 and the housing 21, the dust seal 60 preventing the ingress of dust from the outside of the housing 21 into the inside of the housing 21, where: the housing 21 and the rotatable shaft 30 contain metal materials which are different from each other, an inner peripheral portion 62 of the dust seal 60 is in sliding contact with the rotatable shaft 30, an outer peripheral portion 63 of the dust seal 60 is in contact with an inner peripheral portion 262 of an opening 261 of the housing 21, the opening 261 allowing the passage of the rotatable shaft 30, an outer end 265, in the direction D1 of the rotation axis of the rotatable shaft 30, of the inner peripheral portion 262 of the opening 261 of the housing 21 includes a chamfered portion 266 having a diameter thereof increasing toward the outside of the opening 261, the dust seal 60 includes a first lip 71 covering the beveled portion 266, and the dust seal 60 does not protrude outwards in the direction D1 of the rotation axis beyond an outermost portion 267 of the opening 261 in the direction D1 of the rotation axis.

[0122] In the case where the housing 21 and the rotary shaft 30 contain metal materials that are different from each other, and water accumulates between the opening 261 of the housing 21 and the rotary shaft 30, electrolytic corrosion (galvanic corrosion) easily occurs. Electrolytic corrosion can be suppressed to some extent by painting the opening 261. However, there are cases where the painting is not satisfactorily applied to the opening 261. For example, if the projection 272 provided at the opening 261 is thin, the painting is not satisfactorily applied to the projection 272. According to one embodiment of the present teachings, the dust seal 60 includes the first lip 71 covering the tapered portion 266 of the opening 261.The first lip 71 covers the chamfered portion 266 so that electrolytic corrosion can be suppressed even if the paint is not satisfactorily applied to the opening 261.

[0123] According to one embodiment of the present teaching, the dust seal 60 does not protrude outward in the direction D1 of the rotation axis to the outermost portion 267 of the opening 261. With this arrangement, the size of the drive unit 20 can be reduced in the width direction.

[0124] The crank arms 35 can be fixed to the rotating shaft 30. If the dust seal 60 protrudes outward beyond the opening 261 of the housing 21, the dust seal 60 may interfere with the crank arms 35 or the like. Since the dust seal 60 does not protrude beyond the opening 261 in this embodiment, interference of the dust seal 60 with the crank arms 35 can be suppressed. [Point 2]

[0125] The drive unit 20 of item 1, wherein the first lip 71 of the dust seal 60 is shaped to extend away from the rotatable shaft 30 while extending outward in the direction D1 of the rotation axis.

[0126] In this arrangement, the beveled portion 266 of the opening 261 can be covered in a suitable manner. [Point 3]

[0127] The drive unit 20 of item 1 or 2, wherein: a groove 271 is provided in the inner peripheral portion 262 of the opening 261 in a circumferential direction of the opening 261, and the outer peripheral portion 63 of the dust seal 60 includes a second lip 72 fitted into the groove 271.

[0128] Since the second lip 72 of the dust seal 60 is fitted into the groove 271 of the opening 261, the dust seal 60 can be fixed to the housing 21. [Point 4]

[0129] The drive unit 20 of item 3, where: the opening 261 has a projection 272 which acts as an outer wall of the grooves 271 in the direction D1 of the axis of rotation, and the beveled portion 266 is provided on the projection 272.

[0130] Even if the paint is not applied satisfactorily to the opening 261, the first lip 71 covers the chamfered portion 266, whereby the electrolytic corrosion can be suppressed. [Point 5]

[0131] The drive unit 20 of item 3 or 4, wherein the second lip 72 of the dust seal 60 is snap-fitted into the groove 271.

[0132] The dust seal 60 can be snap-fitted to the housing 21. Furthermore, the intrusion of water and dust into the interior of the housing 21 can be more effectively prevented. [Point 6]

[0133] The drive unit 20 of item 4, wherein the first lip 71 and the second lip 72 of the dust seal 60 hold the projection 272 therebetween by an elastic force.

[0134] With this arrangement, a gap is less likely to form between the first lip 71 and the chamfered portion 266, and thus electrolytic corrosion can be more effectively suppressed. Furthermore, the intrusion of water and dust into the interior of the housing 21 can be more effectively suppressed. [Point 7]

[0135] The drive unit 20 of item 1 or 2, with the dust seal 60 pressed into the opening 261.

[0136] The dust seal 60 is pressed into the opening 261 and can therefore be attached to the housing 21. [Point 8]

[0137] The drive unit 20 according to any one of items 1 to 7, wherein the inner peripheral portion 62 of the dust seal 60 includes a sealing lip 65 in sliding contact with the rotatable shaft 30.

[0138] With this arrangement, the flow of oil from the inside to the outside of the housing 21 and the intrusion of water and dust from the outside into the inside of the housing 21 can be suppressed. [Point 9]

[0139] The drive unit 20 of item 8, wherein the inner peripheral portion 62 of the dust seal 60 further includes a dust lip 66 which is in sliding contact with the rotatable shaft 30 and is arranged outside the sealing lip 65 in the direction D1 of the rotation axis.

[0140] With this arrangement, the penetration of dust from outside into the interior of the housing 21 can be suppressed. [Point 10]

[0141] The drive unit 20 according to any one of items 1 to 9, wherein the housing 21 contains a metal material containing magnesium as a main component.

[0142] This arrangement allows the weight of the drive unit 20 to be reduced. [Point 11]

[0143] The drive unit according to any one of items 1 to 10, wherein the rotatable shaft 30 includes a metal material containing iron as a main component.

[0144] With this arrangement, the degree of rigidity and strength required for the rotatable shaft 30 can be realized at low cost. [Point 12]

[0145] An electrically assisted bicycle 1 including the drive unit 20 of any one of items 1 to 11.

[0146] With this arrangement, the electrically assisted bicycle 1 including the drive unit 20 can be realized in a very water-resistant and compact manner.

[0147] The present teaching is particularly useful in the field of electrically assisted bicycles. 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 2007-230411 A

[0002]

Claims

[1] A drive unit (20) for an electrically assisted bicycle (1), the drive unit (20) comprising: an electric motor (25); a housing (21) which accommodates the electric motor (25); a rotatable shaft (30) which is rotatable about a rotation axis and which is rotatably supported by the housing (21) and is partially exposed on the outside of the housing (21); and an annular dust seal (60) provided between the rotatable shaft (30) and the housing (21), the dust seal (60) is provided to prevent the penetration of dust from the outside of the housing (21) into the interior of the housing (21), wherein the housing (21) and the rotatable shaft (30) contain metal materials which are different from each other, an inner peripheral portion (62) of the dust seal (60) is in sliding contact with the rotatable shaft (30), an outer peripheral portion (63) of the dust seal (60) is in contact with an inner peripheral portion (262) of an opening (261) of the housing (21), the rotatable shaft (30) passes through the opening (261), an outer end (265), in the direction (D1) of the rotational axis of the rotatable shaft (30), of the inner peripheral portion (262) of the opening (261) of the housing (21) includes a chamfered portion (266) having a diameter which increases towards the outside of the opening in the direction (D1) of the rotational axis of the rotatable shaft (30), the dust seal (60) includes a first lip (71) covering the beveled portion (266), and the dust seal (60), in the direction (D1) of the axis of rotation of the rotatable shaft (30), does not protrude outwards beyond an outermost portion (267) of the opening (261) in the direction (D1) of the axis of rotation of the rotatable shaft (30). [2] The drive unit (20) of claim 1, wherein the first lip (71) of the dust seal (60) is shaped to extend away from the rotatable shaft (30) while extending outward in the direction (D1) of the rotational axis of the rotatable shaft (30). [3] The drive unit (20) of claim 1 or 2, wherein a groove (271) is provided in the inner peripheral portion (262) of the opening (261) in a circumferential direction of the opening (261), and the outer peripheral portion (63) of the dust seal (60) includes a second lip (72) fitted into the groove (271). [4] The drive unit (20) of claim 3, wherein the opening (261) has a projection (272) acting as an outer wall of the groove (271) in the direction (D1) of the rotation axis of the rotatable shaft (30), and the chamfered portion (266) is provided on the projection (272). [5] The drive unit (20) of claim 3 or 4, wherein the second lip (72) of the dust seal (60) is snap-fitted into the groove (271). [6] The drive unit (20) of claim 4, wherein the first lip (71) and the second lip (72) of the dust seal (60) hold the projection (272) therebetween by an elastic force. [7] The drive unit (20) of claim 1 or 2, wherein the dust seal (60) is press-fitted into the opening (261). [8] The drive unit (20) of any one of claims 1 to 7, wherein the inner peripheral portion (62) of the dust seal (60) includes a sealing lip (65) in sliding contact with the rotatable shaft (30). [9] The drive unit (20) of claim 8, wherein the inner peripheral portion (62) of the dust seal (60) further includes a dust lip (65) in sliding contact with the rotatable shaft (30) and disposed outside the seal lip (65) in the direction (D1) of the rotational axis of the rotatable shaft (30). [10] The drive unit (20) of any one of claims 1 to 9, wherein the housing (21) contains a metal material containing magnesium as a main component. [11] The drive unit (20) of any one of claims 1 to 10, wherein the rotatable shaft (30) comprises a metal material containing iron as a main component. [12] An electrically assisted bicycle (1) incorporating the drive unit (20) of any one of claims 1 to 11.

Images