JP3901996B2 - Housing structure for electric drive unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric drive device using an electric motor, and more particularly to a housing alignment structure including divided casings.
[0002]
[Prior art]
For example, in a battery-assisted bicycle, an electric drive device for assisting the pedal effort is provided in connection with the pedal crankshaft to assist the pedal effort from the pedal. In this electric drive device, a drive shaft is constituted by a pedal crankshaft and a drive sleeve coaxial with the pedal crankshaft, a sprocket is fixed on the drive sleeve, and this is connected to a drive wheel (for example, a rear wheel) via a chain. The output shaft of the electric motor serving as auxiliary power is connected to the drive sleeve, and the output of the electric motor is transmitted to the rear wheel via the drive sleeve to give a rotational driving force. On the other hand, the pedal crankshaft connected to the pedal is also connected to the drive sleeve via a planetary gear mechanism or the like, and the rear wheel is driven to rotate via the drive sleeve by the pedal depression force. As a result, the pedal depression force and the driving force of the electric motor are fused on the driving sleeve, and the rear wheel is driven by the resultant force.
[0003]
The pedaling force applied to the pedal crankshaft is detected by torque detecting means. In accordance with the detected pedal force, the control circuit calculates the power to be assisted and drives the electric motor with a predetermined assist ratio.
[0004]
In such an electric drive device, a torque detecting means, a planetary gear mechanism, and a control circuit are integrally assembled together with an electric motor and stored in a casing. The electric drive unit integrated into a casing is attached near the pedal crankshaft in the center of the vehicle body.
[0005]
This casing is divided into three in the center and left and right for assembly and manufacture, and an integral casing is formed by sandwiching the center housing between the left and right cases and connecting them with bolts.
[0006]
A gasket is provided on the mating surface of the casing composed of such three divided bodies to prevent leakage of a lubricant such as grease and oil, and surface processing is performed to ensure sealing performance. Also, knock pins are machined to align the central housing with the left and right cases and to align the drive shaft and motor output shaft between the left and right cases.
[0007]
In this case, when the flange part which becomes the mating surface of the left and right cases is made thin in order to reduce the weight of the casing, the surface pressure of the seal is reduced, so that a general material such as synthetic paper cannot be used as the gasket material. In order to ensure sealing performance, it is necessary to process the entire mating surface to ensure flatness, and as a gasket material, it is necessary to use a special gasket with strong elasticity made of silicon rubber or carbon fiber. was there.
[0008]
[Problems to be solved by the invention]
However, the entire processing of the mating surfaces and the knock pin processing are troublesome, and the number of man-hours for the manufacturing process increases and the productivity is lowered. Further, since the drive shaft extending between the divided bodies is accommodated in the casing, the shafts need to be aligned, center alignment and angle phase alignment are necessary, and the assembling work of the divided bodies becomes troublesome. In addition, the above-described special gasket must be used in accordance with the shape of the motor chamber or the speed reducer chamber that accommodates the motor, which complicates the assembly process and increases the cost.
[0009]
The present invention has been made in consideration of the above prior art, and an object thereof is to provide a housing mating surface structure of an electric drive device that increases productivity and reduces cost.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an electric motor is accommodated in a casing, and has a motor output shaft of the electric motor and a drive shaft parallel to the motor output shaft, and the casing has a plurality of surfaces perpendicular to the drive shaft. In the housing alignment structure of the electric drive device divided into two, an annular projection is provided along one peripheral edge of the mating surface of the divided body of the plurality of casings, and the annular projection is fitted to the other mating surface Provided is a housing alignment structure for an electric drive device characterized in that an annular groove is formed.
[0011]
According to this configuration, the annular groove is provided along one peripheral edge of the divisional mating surface of the casing, and the annular projection to be fitted to the annular groove is provided on the other mating surface, thereby ensuring the sealing performance of the casing. The casing divided bodies can be aligned with each other, and the shafts of the drive shaft and the motor output shaft arranged across the divided surfaces can be aligned.
[0012]
Thereby, the knock pin processing and the special gasket for the surface processing and positioning of the mating surfaces can be omitted. For example, sufficient sealing performance can be easily secured by filling the annular groove with a liquid (sol) general-purpose sealing material. Therefore, the manufacturing process is simplified, productivity is increased, and costs are reduced.
[0013]
In a preferred configuration example, the casing includes a central housing and a left case and a right case sandwiching the central housing, and a motor chamber in which the electric motor is accommodated, and the electric motor and the drive shaft are coupled in the casing. A reduction gear chamber in which a reduction mechanism is accommodated, wherein the motor chamber and the reduction gear chamber are surrounded by the annular protrusion and the annular groove at a mating surface between the central housing and the left and right cases.
[0014]
According to this configuration, since the motor chamber and the speed reducer chamber are sealed and separated by the engagement of the annular protrusion and the annular groove, respectively, there is no leakage of lubricant such as grease and oil filled in the speed reducer chamber. The drive shaft and the motor output shaft can be aligned more reliably.
[0015]
In a further preferred configuration example, the central housing is made of a resin material, and the left and right cases are made of a metal material.
[0016]
According to this configuration, the left and right cases made of a metal material ensure sufficient strength of the casing, and the center housing is made of a resin material, so that weight reduction is achieved, and the annular protrusion or the annular groove is formed by injection molding. Can be formed with high accuracy. In particular, by using a thermosetting resin, it is possible to sufficiently withstand high temperatures due to motor heat generation, and to improve water resistance and insulation.
[0017]
In a further preferred configuration example, the electric drive device is an electric drive device for assisting pedal depression force of a battery-assisted bicycle.
[0018]
According to this configuration, by applying the structure of the present invention to the electric motor for assisting the pedaling force of the battery-assisted bicycle, productivity is improved, and weight reduction is realized particularly in a bicycle structure that requires a reduction in size and weight. Thus, load reduction and cost reduction can be achieved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view of a battery-assisted bicycle equipped with an electric drive device according to an embodiment of the present invention.
[0020]
The battery-assisted bicycle 1 includes an electric drive device 4 according to the present invention mounted on the hanger portion 3 at the substantially center of the vehicle body frame 2, and a pedaling force for rotating the pedal crankshaft 6 by stepping on the pedal 5. The electric driving device 4 is combined with the power of an electric motor, which will be described later, and the rear wheel 7 is driven by the resultant force. As will be described later, the electric drive unit 4 has a sprocket on the drive shaft, and the rotation of the sprocket is transmitted to the rear wheel 7 by a chain 8 via a known free wheel.
[0021]
The electric drive device 4 is suspended and supported by a suspension bolt as will be described later with respect to a bracket 9 fixed (or integrally molded) to the vehicle body frame 2. Reference numeral 10 denotes a battery for driving the electric motor in the electric drive unit 4.
[0022]
FIG. 2 is a horizontal sectional view of the electric drive device according to the present invention.
The electric drive device 4 is configured by housing an electric motor 12 and a drive shaft 13 in a casing 11. The casing 11 is divided into three as will be described later, and includes a central housing 14 and a left case 15 and a right case 16 that sandwich the housing 11 from both sides. The electric motor 12 includes a motor output shaft 17, a rotor 18 fixed to the motor output shaft 17, and a stator 19 fixed in the casing 11 so as to face the outer periphery of the rotor 18. The drive shaft 13 includes a pedal crankshaft 6 (manpower input shaft) connected to the pedal 5 (FIG. 1) and a fusion sleeve 20 that is rotatably fitted on the outer periphery of the pedal crankshaft 6. A sprocket 21 is fixed on the fusion sleeve 20 and connected to the rear wheel 7 (FIG. 1) via the chain 8.
[0023]
A gear 22 is formed at the end of the motor output shaft 17. The first gear 24 of the intermediate shaft 23 meshes with the gear 22. A first gear 24 and a second gear 25 that is integral with the first gear 24 and smaller in diameter are mounted on the intermediate shaft 23. The second gear 25 meshes with a large-diameter gear 27 fixed to the fusion sleeve 20 via a ratchet 26. A reduction gear mechanism 72 (first reduction mechanism) is formed by such an intermediate shaft 23 and the two-stage integrated first and second gears 24 and 25 attached thereto. As a result, the rotational driving force of the electric motor 12 is decelerated by the reduction gear mechanism 72 and transmitted to the fusion sleeve 20 via the large-diameter gear 27 to drive the rear wheels.
[0024]
The pedal crankshaft 6 is connected to a planetary gear mechanism 29 (second reduction mechanism) via a ratchet 28. The planetary gear mechanism 29 is connected to the fusion sleeve 20, transmits the pedal depression force from the pedal crankshaft 6 to the fusion sleeve 20, and drives the rear wheels by the depression force.
[0025]
The planetary gear mechanism 29 includes a carrier 30 that is driven in one direction by a ratchet 28, a planetary gear 31 that is rotatable about the carrier 30, a ring gear 71 that is fixed to the casing on the outer peripheral side of the planetary gear 31, The sun gear 32 is fixed to the fusion sleeve 20 on the inner peripheral side of the planetary gear 31. The rotational force of the pedal crankshaft 6 revolves and rotates the planetary gear 31 through the carrier 30 from the ratchet 28, rotates the sun gear 32, and transmits the rotational force due to the pedaling force to the fusion sleeve 20 to transmit the rear wheel to the rear wheel. To drive.
[0026]
The central housing 14 of the casing 11 divided into three is formed by injection molding of a resin material such as PBT (polybutyl terephthalate). The left case 15 and the right case 16 sandwiching the central housing 11 are formed of an ADC (aluminum die cast alloy) material.
[0027]
The casing 11 is assembled by connecting the left case 15 and the right case 16 with fastening bolts 33 at a plurality of locations (for example, 5 locations). In this example, the fastening bolt 33 is inserted from the left case 15 side, and is screwed into a female screw portion formed in the right case 16 so that both the cases 15 and 16 are fastened and joined.
[0028]
The casing 11 is fixed and held on a vehicle body bracket 9 fixed to the vehicle body frame by suspension bolts 34 at a plurality of locations (for example, three locations). In this case, as shown in the drawing, the width between the body brackets 9 disposed in the respective suspension portions is narrower than the width of the casing 11, so that a collar 35 serving as a spacer is attached to the suspension bolt 34 and the suspension bolt 34 and this are screwed. The right and left cases 15 and 16 are fastened and fixed by the mating nut 36.
[0029]
The end portion of the pedal crankshaft 6 and the end portion of the fusion sleeve 20 constituting the drive shaft 13 are supported by the left case 15 and the right case 16 via bearings 37 and 38, respectively. The drive shaft 13 is stably and firmly held by supporting the bearing portions of the drive shaft 13 on the left and right cases 15 and 16 made of a metal material having a high strength as described above.
[0030]
The left end of the motor output shaft 17 of the electric motor 12 is supported on the left case 15 via a bearing 39. In this example, the bearing 40 that holds the right end of the motor output shaft 17 is provided in the central housing 14 made of resin. In this case, an arc-shaped metal convex wall (not shown) is provided integrally with the right case 16 so as to hold the bearing 40 at a plurality of locations along the outer peripheral surface of the bearing 40 and protrudes toward the central housing side. By fixing and holding the bearing 40 by the convex wall, the bearing 40 is stably and firmly fixed and held as in the case where the bearing 40 is held in a case made of a metal material. Further, there is no positional deviation due to molding error or deformation of the resin material. A notch (not shown) is provided in the resin material of the central housing 11 where such a convex wall is disposed so as not to prevent insertion of the convex wall from the right case 16 made of a metal material.
[0031]
As will be described later, the inside of the casing 11 includes a motor chamber that houses the electric motor 12, a speed reducer chamber that houses the reduction gear 25, the planetary gear mechanism 29, and the like, and a motor control circuit board (not connected) that is energized by an FET or the like. It is divided into a control room that accommodates (shown).
[0032]
In the present invention, annular protrusions 45 and 55 are formed on the dividing surface between the central housing 14 and the left and right cases 15 and 16 of the casing 11 divided into three along the peripheral edge of the mating surface on the central housing side as described later. The annular grooves 44 and 54 into which the annular protrusions 45 and 55 are fitted are formed on the mating surfaces on the left and right case sides. As a result, the sealing performance of the casing 11 is ensured, and the center housing 14 that is a casing divided body and the left and right cases 15 and 16 can be aligned, and the drive shaft 13 and the motor output shaft that are disposed across the dividing surface. 17 axis alignment is possible.
[0033]
FIG. 3 is a side view as seen from the inner surface side (right side) of the left case 15 constituting the casing 11, and FIG. 4 is a cross-sectional configuration diagram of the AA portion thereof.
[0034]
A partition wall 43 that partitions the periphery of the motor chamber 41 and the control chamber 42 and the two chambers is formed on the inner surface side of the left case 15. The partition wall 43 between the motor chamber 41 and the control chamber 42 is formed with an opening 51 through which a signal cable, a power cable and the like are inserted. An annular groove 44 surrounding each of the motor chamber 41 and the control chamber 42 is formed along the partition wall 43 on the mating surface with the central housing 14. An annular protrusion 45 (FIG. 5) provided on the central housing 14 described later is fitted into the annular groove 44. As a result, the motor chamber 41 and the control chamber 42 are sealed, and alignment with the central housing 14 (FIGS. 2 and 5) is performed.
[0035]
Fastening attachment holes 46 are formed at five locations along the outer peripheral edge of the left case 15, and the aforementioned fastening bolts 33 (FIG. 2) are inserted therethrough. Further, suspension brackets 47 are provided at three positions so as to protrude from the outer peripheral edge of the left case 15, and suspension attachment holes 48 are formed respectively. The above-described suspension bolts 34 (FIG. 2) are inserted into these suspension mounting holes 48.
[0036]
The pedal crankshaft 6 is inserted into the pedal crankshaft insertion hole 49 via the bearing 37 shown in FIG. Further, the end portion of the motor output shaft 17 is supported by the motor bearing portion 50 through the bearing 39 of FIG.
[0037]
The control chamber 42 accommodates a printed circuit board (not shown) on which, for example, six FETs (not shown) are mounted in a line. These six FETs are in thermal contact with the inner surface of the left case 15 through a heat sink (not shown) made of a metal material to dissipate heat. The heat sink may be formed integrally with the case material on the inner surface of the left case 15. The six FETs are pressed against the inner wall surface of the case from the inside of the case by, for example, a common pressing plate (not shown). The presser plate is tightened from the outside of the case with screws (not shown) through, for example, two through holes 53 provided in the case to press-contact each FET to the inner wall surface of the case. Reference numeral 52 denotes a dent for screw head escape of six screws for fixing the FET to the heat sink.
[0038]
FIG. 5 is a cross-sectional configuration diagram of the central housing 14.
On the left and right side surfaces of the central housing 14, there are respectively an annular protrusion 45 fitted in the annular groove 44 of the left case 15 and an annular protrusion 55 fitted in an annular groove 54 of the right case 16 shown in FIGS. It is formed. Fastening bolt insertion holes 56 are formed along the peripheral edge of the central housing 14 at five positions corresponding to the aforementioned fastening mounting holes 46 (FIG. 3).
[0039]
The interior of the central housing 14 is separated by a partition wall 57 into a motor chamber 41, a control chamber 42 (see FIG. 3), and a reducer chamber 58. The motor chamber 41 houses the electric motor 12 as described above, and the control chamber 42 houses a printed circuit board to which an FET or the like is bonded. The reduction gear chamber 58 houses the reduction gear mechanism 72 and the planetary gear mechanism 29 shown in FIG. The left end portion of the intermediate shaft 23 (FIG. 2) of the reduction gear mechanism 72 is fitted and supported in a bearing recess 59 formed in the reduction gear chamber 58. A pedal crankshaft insertion hole 62 is formed in the left partition wall forming the speed reducer chamber 58, and the pedal crankshaft 6 (FIG. 2) is inserted therethrough.
[0040]
A motor output shaft insertion hole 60 is formed in the right wall portion of the partition wall 57 forming the motor chamber 41, and the motor output shaft 17 is inserted through the bearing 40 (FIG. 2) as described above. Reference numeral 61 denotes a bearing fitting portion.
[0041]
6 is a view of the right case 16 as viewed from the inner surface side (left side), and FIG. 7 is a cross-sectional configuration diagram of the CC portion of FIG.
[0042]
A partition wall 63 that forms a reduction gear chamber 58 is provided along the outer peripheral edge of the right case 16. An annular groove 54 is formed along the mating surface of the partition wall 63 with the central housing 14. An annular protrusion 55 on the central housing 14 side is fitted into the annular groove 54, and the seal of the reduction gear chamber 58 and the alignment of the central housing 14 and the right case 16 are performed.
[0043]
As in the case of the left case 15, suspension brackets 64 are provided at three locations on the outer peripheral edge of the right case 16, and suspension attachment holes 65 through which the suspension bolts 34 (FIG. 2) are inserted are formed.
[0044]
Corresponding to the fastening holes 46 (FIG. 3) of the left case 15 through which the five fastening bolts 33 (FIG. 2) are respectively inserted and the fastening bolt insertion holes 56 of the central housing 14 aligned therewith, the right case 16 Fastening screw holes 66 are formed at five positions on the peripheral edge. The fastening bolt 33 is screwed into the fastening screw hole 66.
[0045]
The right end portion of the intermediate shaft 23 (FIG. 2) is fitted and supported in a bearing recess 67 formed on the inner surface of the right case 16.
[0046]
A drive shaft insertion hole 68 is opened through the right case 16, and the drive shaft 13 including the pedal crankshaft 6 and the fusion sleeve 20 shown in FIG. Reference numeral 69 denotes a bearing fitting portion that holds the bearing 38 (FIG. 2).
[0047]
The right case 16 is formed of an aluminum die-cast alloy (ADC material) formed in the same manner as the left case 15 described above, and forms an integral casing 11 (FIG. 2) with the resin central housing 14 sandwiched from the left and right. To do.
[0048]
In the above embodiment, the liquid sealant may be applied to the fitting portions of the annular protrusions 45 and 55 of the central housing 14 and the annular grooves 44 and 54 of the left and right cases 15 and 16 fitted thereto. As a result, the sealing performance is ensured, the special gasket which has been conventionally required is not required, the assembly work is facilitated, and the cost can be reduced.
[0049]
Further, the fitting gap between the annular protrusions 45, 55 and the annular grooves 44, 54 is partially widened so as to absorb the misalignment between the annular groove and the annular protrusion due to resin molding deformation or the like. It may be.
[0050]
In addition, when aligning the shaft between the center housing and the left and right cases, center alignment and angle phase alignment are required, but in order to align these accurately, a fitting groove for center alignment is provided near the shaft. It is also possible to provide a phase fitting groove fitting portion in the provided portion. In order to realize such a configuration, in order to prevent interference at a portion other than the center alignment portion and the phase alignment portion, the gap may be increased and the resin molding distortion may be released through the increased clearance.
[0051]
【The invention's effect】
As described above, according to the present invention, the annular groove is provided along one peripheral edge of the divided mating surface of the casing, and the annular protrusion is fitted on the other mating surface, thereby ensuring the sealing performance of the casing. In addition, the casing divided bodies can be aligned with each other, and the shafts of the drive shaft and the motor output shaft arranged across the divided surfaces can be aligned.
[0052]
Thereby, the knock pin processing and the special gasket for the surface processing and positioning of the mating surfaces can be omitted. For example, sufficient sealing performance can be easily secured by filling the annular groove with a liquid (sol) general-purpose sealing material. Therefore, the manufacturing process is simplified, productivity is increased, and costs are reduced.
[Brief description of the drawings]
FIG. 1 is an overall view of a battery-assisted bicycle to which an electric drive device of the present invention is applied.
FIG. 2 is a horizontal sectional configuration diagram of the electric drive device according to the embodiment of the present invention.
FIG. 3 is an inner surface view of a left case of the electric drive device of FIG. 2;
4 is a cross-sectional configuration view taken along the line BB in FIG. 3;
5 is a cross-sectional configuration diagram of a central housing of the electric drive device of FIG. 2;
6 is an inner surface view of a right case of the electric drive device of FIG. 2. FIG.
7 is a cross-sectional configuration diagram taken along the line CC of FIG. 6;
[Explanation of symbols]
1: battery-assisted bicycle, 2: body frame 3: hanger part, 4: electric drive device,
5: Pedal, 6: Pedal crankshaft, 7: Rear wheel, 8: Chain,
9: bracket, 10: battery, 11: casing, 12: electric motor,
13: Drive shaft, 14: Central housing, 15: Left case, 16: Right case,
17: Motor output shaft, 18: Rotor, 19: Stator,
20: Fusion sleeve, 21: Sprocket, 22: Gear,
23: intermediate shaft, 24: first gear, 25: second gear, 26: ratchet,
27: Large-diameter gear, 28: Ratchet, 29: Planetary gear mechanism, 30: Carrier,
31: Planetary gear, 32: Sun gear, 33: Fastening bolt, 34: Suspension bolt,
35: collar, 36: nut, 37: bearing, 38: bearing,
39: Bearing, 40: Bearing, 41: Motor room, 42: Control room,
43: partition wall, 44: annular groove, 45: annular projection, 46: mounting hole for fastening,
47: Suspension bracket, 48: Suspension mounting hole, 49: Pedal crankshaft insertion hole,
50: Motor bearing, 51: Opening, 52: Recess,
53: Presser plate mounting through-hole, 54: annular groove, 55: annular projection,
56: Fastening bolt insertion hole, 57: Partition wall, 58: Reducer chamber,
59: Recess for supporting the intermediate shaft, 60: Motor output shaft insertion hole,
61: Bearing fitting portion, 62: Pedal crankshaft insertion hole, 63: Partition wall,
64: suspension bracket, 65: mounting hole for suspension, 66: screw hole for fastening,
67: Recess for supporting the intermediate shaft, 68: Drive shaft insertion hole, 69: Bearing fitting portion,
71: Ring gear, 72: Reduction gear mechanism.

Claims (2)

An electric motor is housed in a casing, has a motor output shaft of the electric motor and a drive shaft parallel to the motor output shaft, and the casing is divided into a plurality of sections on a plane perpendicular to the drive shaft. In structure
An annular protrusion is provided along one peripheral edge of the mating surface of the divided body of the plurality of divided casings, and an annular groove into which the annular protrusion is fitted is formed on the other mating surface ,
The casing includes a central housing and a left case and a right case sandwiching the central housing, and a motor chamber in which the electric motor is accommodated and a speed reduction mechanism that couples the electric motor and the drive shaft are accommodated in the casing. A reduction gear chamber, and the motor chamber and the reduction gear chamber are surrounded by the annular protrusion and the annular groove at the mating surface of the central housing and the left and right cases ,
A housing alignment structure for an electric drive device, wherein the central housing is made of a resin material, and the left and right cases are made of a metal material.   2. The housing alignment structure for an electric drive device according to claim 1, wherein the electric drive device is an electric drive device for assisting pedal depression force of an electric assist bicycle.

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