TWI773222B - Electric bicycle booster of inner-rotor-type wheel hub motor using one-stage involute planetary gear reduction mechanism with small teeth number differences - Google Patents

Abstract

An electric bicycle power assist device with an inner rotor type hub motor of a first-order involute planetary gear deceleration transmission mechanism, comprising a stator and a rotor hub motor, a rotor and a hub shaft with an eccentric shaft combined into one, a stator bracket , a ring gear with an annular internal gear, a planetary gear with a pin hole, an output intermediate piece with a pin and a self-lubricating bushing, a fixed shaft on the left and right sides of the hub, and a hub shell with left and right side covers of the shell. The stator bracket is an integral component with the fixed shaft on the right side of the hub. The rotor and the hub rotating shaft rotate inside the stator through two bearings in the left and right fixed shafts of the hub. The hub motor is positioned inside the stator bracket by means of the nut and the C-shaped retaining ring. The eccentric shaft of the hub shaft drives the planetary gear to make a planetary motion around the ring gear fixed on the stator bracket. The planetary gear drives the output intermediate member to rotate at a constant speed through the engagement of holes and pins, and then interferes with the output in the casing. The intermediate piece drives the hub shell to do output rotation. In this way, the first-order involute planetary gear reduction transmission mechanism with small teeth difference, which can achieve high reduction ratio and high mechanical efficiency with a small number of teeth, is applied to the inner rotor type in-wheel motor, so as to realize the inner-rotor type in-wheel motor of electric bicycles. The miniaturization of the booster device, high mechanical efficiency and the effect of boosting the booster.

Description

Electric bicycle booster with first-order involute less tooth difference planetary gear reduction transmission mechanism with inner rotor type hub motor

The invention relates to a first-order involute less tooth difference planetary gear reduction transmission mechanism of an inner rotor type hub motor booster of an electric bicycle, in particular to an inner rotor of an electric bicycle that can realize miniaturization, high mechanical efficiency and greatly improve the boosting effect. The technology of rotor-type in-wheel motor power transmission mechanism.

Due to the continuous relationship between the new crown pneumonia epidemic, people in Europe and the United States are afraid of taking crowded and closed subways or buses. Bicycles that are both environmentally friendly and can maintain social distance have become a popular means of transportation. From London, Paris, Berlin, Milan, the United States Philadelphia, Denver, Bogota in Colombia, Sydney, Melbourne and other major cities in Australia have expanded bicycle lanes and subsidized the purchase of bicycles to encourage citizens to use bicycles as a means of transportation. The production capacity of major bicycle factories is in short supply. When commuting to get off work or leisure destinations are far away or there are uphill sections on the road, electric bicycles with motor-assisted devices are more suitable for the needs. Therefore, the electric bicycle market has been growing in recent years, and has maintained a fairly high sales boom in European countries. Therefore, electric bicycles are an important key direction for Taiwan's bicycle industry to continue to lead and make profits in the world bicycle industry.

At present, the general electric bicycle power assist devices on the market use no Brush hub motors are divided into brushless gearless hub motors and brushless gear hub motors according to whether the motor passes through a gear reduction mechanism. FIG. 1 is an actual diagram of a gear reduction mechanism in a brushless geared hub motor commonly used in the market, including a central gear 51 , three intermediate idler gears 52 , a wheel disc 53 (fixed part) and a ring gear 54 . The gear reducers with brushless gear hub motors on the market all use a centering gear system. Although the number of teeth of the ring gear 54 is many, such as 93 teeth, its reduction ratio is not high. If the number of teeth of the center gear 51 is 21, the reduction ratio is only -4.4 (minus sign indicates that the output and input are reversed). The new patent No. M484555 "Bicycle booster motor with one-way function" adopts a compound gear train. The large-diameter tooth part and the small-diameter tooth part pinned on the same shaft mesh with the central gear and the ring gear respectively. The reduction ratio can be obtained through gear matching (for example, the 20 teeth of the central gear drive the 60 teeth of the large-diameter tooth part, and the 20 teeth of the small-diameter tooth part that rotates with the large-diameter tooth part drive the 93 teeth of the ring gear) to obtain a higher reduction ratio than the centering gear train. (about -14), but also requires large gears. Therefore, the gear reduction mechanism of the in-wheel motor on the market has poor deceleration and torque enhancement effects, resulting in less power to climb long steep slopes.

The sun gear in the ordinary planetary gear reducer is removed and the difference between the number of teeth of the fixed ring gear and the planetary gear is very small, which is called a planetary gear reducer with small tooth difference. Compared with the reduction mechanism with centering wheel (including simple and compound gear trains), the planetary gear reducer with small tooth difference has a higher reduction ratio, so it can improve the output torque effect of the hub motor, and the number of teeth can be smaller, that is Small size and weight. At present, the first-order small tooth difference planetary gear reducer can be divided into involute small tooth difference reducer, cycloidal pinwheel reducer and harmonic reducer. However, the cycloid reducer needs a fairly precise center distance and a fairly precise tooth profile, otherwise the output speed and torque are quite easy to fluctuate. Invention Patent No. I694952 "The Harmonic Gear Transmission Mechanism of Electric Bicycle Electric Power Assist" The harmonic reducer is used in the power assist device of the electric bicycle, but the harmonic reducer has a flexible wheel, so the rigidity and strength are poor, the life is often low, and the manufacturing cost is also quite high. As for the involute small tooth difference reducer, it does not have the shortcomings of the above two reducers, but the tooth profile design of its gear set is more difficult, and it is easy to have interference on the tooth profile. Therefore, it is necessary to use shift gears and non-standard modules Design technology can overcome the difficulty of tooth profile design.

Another common type is the RV reducer. Since the first stage uses the center wheel (sun gear) to drive the planetary gears, and the second stage uses the cycloidal pinwheel reduction mechanism with small tooth difference, the structure is complex, the volume is relatively large, and the weight is relatively high. It is heavy, so it is not suitable as a power assist device for electric bicycles.

The present invention is mainly aimed at the lack of the gear reduction mechanism of the inner rotor type hub motor of the current electric bicycle and the application of the conventional gear reducer to the electric bicycle power assist device, and is a new invention.

，其中z _i 代表齒輪i的齒數。如前所述，單式與複式齒輪系其93齒的圈齒的減速比才-4.4與-14(尚需大徑齒部60齒)，使用一階漸開線少齒差行星齒輪減速機構能以較少的齒數即可達成較高的減速比，如行星齒輪11、齒圈12的齒數各為20與21時減速比可達成-20；各為30與31時減速比可達成-30；各為40與41時減速比可達成-40。顯而易見，使用一階漸開線少齒差行星齒輪減速機構於電動自行車的內轉子式輪轂電機之動力傳動機構上，可以實現小型化、輕量化與提升助力的效果。此外一階相較二階行星齒輪減速機構其機械效率可以達到更高。 The main purpose of the present invention is to provide a first-order involute planetary gear reduction mechanism with small tooth difference in the power assist device of an electric bicycle, mainly applying the first-order involute small tooth difference planetary gear reduction mechanism to the inner rotor type of the electric bicycle. On the hub motor, in order to achieve the effect of miniaturization, high mechanical efficiency and boosting power. 2 is a schematic diagram of the first-order involute planetary gear reduction mechanism with small tooth difference used in the present invention, wherein the hub rotating shaft 23 includes an eccentric rotating shaft 24, which are joined into one body or integrally formed, with teeth of the annular internal gear. The ring 12 is a fixed part. The eccentric shaft 24 of the hub shaft 23 drives the planetary gear 11 to make a planetary motion around the fixed ring gear 12, and drives the output intermediate member 14 (or output shaft) and the input of the hub shaft 23 by means of hole-pin engagement. The shafts rotate on the same axis. This kind of hole-pin engagement method is that there are four or six pin holes 13 on the planetary gear 11, and there are also four or six pins 15 on the corresponding output intermediate member 14 and a self-lubricating bushing 16 set on the pins, but must meet the requirements. dh = _{d b +} 2e, wherein _dh is the diameter of the pin hole 13, _db is the diameter of the outer circle of the self-lubricating bushing 16, and e is the eccentricity of the eccentric shaft. In this way, the hole-pin engagement method is equivalent to a parallelogram mechanism, so the rotational speed of the planetary gear 11 is transmitted to the output intermediate member 14 through the hole-pin engagement method to perform a constant-velocity centered rotational motion. 3 is an exploded schematic diagram of a first-order involute planetary gear reduction mechanism with small tooth difference (the conventional keyway and flat key between the shaft and the gear are not shown), and the reduction ratio formula is:

, where zi represents the number of teeth of gear i _. As mentioned above, the reduction ratios of the 93-tooth ring teeth of the single-type and compound-type gear systems are only -4.4 and -14 (the large-diameter teeth are still required to be 60 teeth), and the first-order involute planetary gear reduction mechanism with small tooth difference is used. A higher reduction ratio can be achieved with a smaller number of teeth. For example, when the teeth of the planetary gear 11 and the ring gear 12 are 20 and 21 respectively, the reduction ratio can reach -20; when the teeth are 30 and 31, the reduction ratio can reach -30 ; When each is 40 and 41, the reduction ratio can reach -40. Obviously, the use of the first-order involute planetary gear reduction mechanism with small tooth difference in the power transmission mechanism of the inner rotor type in-wheel motor of the electric bicycle can achieve the effect of miniaturization, light weight and boosting power. In addition, the mechanical efficiency of the first-order planetary gear reduction mechanism can be higher than that of the second-order planetary gear reduction mechanism.

The technical means to achieve the purpose of the present invention include three sub-assemblies of a first-order involute planetary gear reduction mechanism with small tooth difference, a hub motor including a stator, a rotor and a hub shaft with an eccentric shaft, and a hub shell. The three sub-assemblies are installed inside the hub shell, and the three sub-assemblies are assembled into an inner-rotor type planetary gear reduction transmission mechanism with a first-order involute small tooth difference with the effect of the present invention through the supporting and connecting members. Electric bikes with in-wheel motors Vehicle booster, the motion sequence of deceleration and boosting is that the eccentric shaft of the hub shaft drives the planetary gear to make a planetary motion around the ring gear fixed on the stator bracket, and the planetary gear transmits its rotational speed at a constant speed through a constant speed mechanism engaged by a hole pin. To the output intermediate member with the same rotation axis as the rotor, the hub shell is driven to rotate by the output intermediate member which is interference fit in the casing. Since the hub shell is connected to the wheel frame by the spokes, finally the hub shell drives the wheel rim to rotate. The fixed shafts on the left and right sides of the wheel hub support the rotating hub casing through two left and right bearings. The wheel hub fixed shaft on the right is an integral component with the stator bracket in the housing. The hub motor is positioned inside the stator bracket by means of a nut and a C-shaped retaining ring, and the ring gear is also locked and fixed to the stator bracket.

11: Planetary gear

12: Ring gear

13: pin hole

14: Output middleware

15: Pins

16: Self-lubricating bushing

17: Screws

21: Stator

22: Rotor

23: Wheel hub shaft

24: Eccentric shaft

25: Nut

26: C-type buckle

27: Right second ball bearing

28: Left second ball bearing

31: Shell body

32: Right side cover of the shell

33: Shell left cover

34: Screws

41: Fixed shaft on the right side of the hub

42: Fixed shaft on the left side of the hub

43: Stator bracket

44: Right ball bearing

45: Left ball bearing

46: Right side seal

47: Left side seal

51: Central gear

52: Idler

53: Roulette

54: Ring gear

Figure 1 is an actual diagram of a gear reduction mechanism in a brushless geared hub motor.

2 is a schematic diagram of the first-order involute planetary gear reduction mechanism with small tooth difference of the present invention.

3 is an exploded schematic view of the first-order involute planetary gear reduction mechanism with small tooth difference of the present invention.

4 is a perspective view of an electric bicycle power assist device according to an embodiment of the present invention.

5 is an exploded view of an electric bicycle power assist device according to an embodiment of the present invention, wherein the housing body and conventional accessories such as bearings, screws and seals are not shown.

6 is a cross-sectional view of an electric bicycle power assist device according to an embodiment of the present invention.

In order to help your examiners to further understand the technical features and means of the present invention, the following specific examples and illustrations are described in detail:

Please refer to FIGS. 4 to 6 at the same time. FIG. 4 is a perspective view of an electric bicycle power assist device according to an embodiment of the present invention; and FIG. 5 is an exploded view of an electric bicycle power assist device according to an embodiment of the present invention. The housing body and conventional accessories such as bearings 27, 28, 44, 45, screws 17, 34, and seals 46, 47 are not shown; FIG. 6 is a cross-sectional view of an electric bicycle power assist device according to an embodiment of the present invention. In the embodiment of the present invention, the electric bicycle power assist device includes three sub-assemblies: a first-order involute planetary gear reduction mechanism with small tooth difference, an inner-rotor hub motor, and a hub shell. The first two sub-assemblies are installed inside the hub shell. , and the three sub-assemblies are assembled by supporting and connecting members into an electric bicycle power assist device with a first-order involute less tooth difference planetary gear reduction transmission mechanism with an inner rotor type in-wheel motor with the effect of the present invention.

The supporting and connecting members include a fixed shaft 41 on the right side of the hub and a fixed shaft 42 on the left side of the hub. A part of the fixed shaft 41 on the right side of the hub and the fixed shaft 42 on the left side of the hub are installed inside the hub shell, and a part is outside the hub shell and can be locked to the front fork or the frame of the frame by a nut (not shown). on the rear fork (not shown).

The hub shell includes a shell body 31 , a right side cover 32 and a left side cover 33 , which are joined by screws 34 . In practical application, the hub shell can be connected to the wheel frame (not shown) by means of spokes (not shown), and the wheel rim is driven by the hub shell to rotate.

The inner rotor type in-wheel motor includes a stator 21 , a rotor 22 installed inside the stator 21 , and a hub rotating shaft 23 with an eccentric rotating shaft 24 is integrated with the rotor 22 . The hub motor is positioned inside the stator bracket 43 by a nut 25 and a C-shaped retaining ring 26 .

The stator bracket 43 is an integral member with the fixed shaft 41 on the right side of the hub.

The rotor 22 and the hub shaft 23 are pivotally connected to the hub right fixed shaft 41 and the hub left fixed shaft 42 via a second right ball bearing 27 and a second left ball bearing 28 , respectively.

The first-order involute planetary gear reduction mechanism with small tooth difference includes a planetary gear 11 with four or six pin holes 13, a ring gear 12 fixed to the stator bracket 43 by screws 17, and a planetary gear 12 with four or six pin holes 13. The output intermediate member 14 of the pin 15 and the self-lubricating bushing 16 sleeved on the pin. The electric bicycle power assist device of the inner rotor type hub motor with the first-order involute less tooth difference planetary gear deceleration transmission mechanism with the effect of the present invention, the movement sequence of deceleration and boosting is that the eccentric rotating shaft 24 of the hub rotating shaft 23 drives the planetary gear 11 to revolve The ring gear 12 performs planetary motion, and the rotational speed of the planetary gear 11 is made constant by the constant speed mechanism in which the pin hole 13 on the planetary gear 11 and the pin 15 on the output intermediate member 14 are engaged with the hole pin of the self-lubricating bushing 16 It is transmitted to the output intermediate member 14 with the same rotation axis as the rotor 21, and then the hub shell is driven to rotate by the output intermediate member 14 which is interference-fitted in the shell body 31. Since the hub shell is connected to the wheel frame by the spokes, the The shell drives the rim to do output rotation.

The hub shell performs output rotational motion on the fixed shaft 41 on the right side of the hub and the fixed shaft 42 on the left side of the hub through a right ball bearing 44 and a left ball bearing 45 respectively.

To sum up, the inner rotor type in-wheel motor of the embodiment of the present invention uses a first-order involute planetary gear reduction mechanism with small tooth difference, which can achieve a high reduction ratio, high mechanical efficiency, and improved power assist effect with a small size gear. Compared with the conventional technologies such as the centering gear reducer used in the inner rotor type in-wheel motor on the market, it has obvious improvement in efficiency and progress. In addition, the present invention has not been seen in publications before the application, and its novelty is beyond doubt. This creation complies with the provisions of the Patent Law, and it is necessary to file an application for an invention patent in accordance with the law. I pray for the review and grant of the patent.

11: Planetary gear

12: Ring gear

13: pin hole

14: Output middleware

15: Pins

16: Self-lubricating bushing

17: Screws

21: Stator

22: Rotor

23: Wheel hub shaft

24: Eccentric shaft

25: Nut

26: C-type buckle

27: Right second ball bearing

28: Left second ball bearing

31: Shell body

32: Right side cover of the shell

33: Shell left cover

34: Screws

41: Fixed shaft on the right side of the hub

42: Fixed shaft on the left side of the hub

43: Stator bracket

44: Right ball bearing

45: Left ball bearing

46: Right side seal

47: Left side seal

Claims (1)

An electric bicycle power assist device with a first-order involute planetary gear reduction transmission mechanism with an inner rotor type hub motor, comprising: a support and a connecting member, including a fixed shaft on the right side of the wheel hub and a fixed shaft on the left side of the wheel hub, which can be connected to the frame. On the front fork or rear fork; the wheel hub shell, including the shell body, the shell right side cover and the shell left side cover, the wheel hub shell at the same time by the right ball bearing and the left ball bearing on the outer side of the fixed shaft on the right side of the hub and the fixed shaft on the left side of the hub The output rotary motion can be connected and driven to rotate the wheel rim; the inner rotor type hub motor includes a stator, a rotor installed on the inner side of the stator, and the hub shaft with an eccentric shaft is integrated with the rotor; the first-order gradual The open-wire planetary gear reduction mechanism with small tooth difference includes a planetary gear with four or six pin holes, a ring gear with annular internal teeth, and an output intermediate with four or six pins and self-lubricating bushings. The rotary motion of the rotor is transmitted to the hub shell with a high reduction ratio; it is characterized in that: the fixed shaft on the right side of the hub is also used as a stator bracket, and a nut and a C-shaped retaining ring are used to position the hub motor inside the stator bracket, the rotor and the hub. The rotating shaft is pivotally connected to the fixed shaft on the right side of the wheel hub and the fixed shaft on the left side of the wheel hub through the second right ball bearing and the second left ball bearing, the gear ring is fixed to the stator bracket by screws, and the output intermediate member is installed in the shell body by interference fit. The eccentric rotating shaft of the hub rotating shaft of the input rotating part drives the planetary gear to make a planetary motion around the fixed ring gear, and the planetary gear is engaged by the pin hole on the planetary gear and the pin on the output intermediate piece and the hole pin of the self-lubricating bushing. The rotational speed of the gear is transmitted to the output intermediate member with the same rotation axis as the rotor at the same speed, and then the output intermediate member drives the hub shell to rotate.

Images