Transmission mechanism and related drive unit

Abstract

A transmission mechanism includes a drive shaft, a receiving member rotating about an axis of rotation coaxial with the drive shaft, a main planetary gear set including a first input member, a second input member, and an output member rigidly connected to the rotating receiving member for rotation therewith; and a kinematic link between the drive shaft and the first input member of the main planetary gear set, the transmission ratio being equal to 1. The transmission mechanism also includes an auxiliary planetary gear set including a first auxiliary input member, a second auxiliary input member, and an auxiliary output member, the first input member of the main planetary gear set being rigidly connected to the first auxiliary input member of the auxiliary planetary gear set for rotation therewith, and the second input member of the main planetary gear set is rigidly connected to the auxiliary output member of the auxiliary planetary gear set. The utility model further relates to a driving unit which comprises a rotating motor and the transmission mechanism, and the rotating motor and the driving shaft are coaxial.

Description

Technical Field

[0001] The utility model relates to a transmission mechanism, and more specifically, it is used to drive automated machines, such as motor vehicles, motorcycles, personal transport vehicles (PTs), vehicles for transporting people with limited mobility or autonomous vehicles, or power take-off devices for driving equipment, such as construction vehicles or agricultural vehicles. Background Art

[0002] Document EP3630521 describes a transmission mechanism, including: a drive shaft driven by an electric motor, a receiving member constituted by a differential rotating around a rotation axis coaxial with the drive shaft, a main planetary gear set, which includes a first input member, a second input member and an output member rigidly connected to the rotating receiving member to rotate therewith; and a connection between the drive shaft and the first input member of the main planetary gear set with a transmission ratio equal to 1. The second input member of the main planetary gear set is driven by at least one intermediate shaft parallel to the drive shaft, and this intermediate shaft is arranged to occupy a large footprint in the axial direction, and it is impossible to generate a high transmission ratio between the drive shaft and the receiving member. In the case where there is not enough gear reduction in the transmission mechanism, the size of the electric motor must be able to transmit high torque, which is not desirable. Summary of the Utility Model

[0003] The utility model attempts to overcome the disadvantages of the prior art and proposes a compact transmission mechanism and transmission ratio, such that high torque and low driving speed can be obtained at the output end of the mechanism when the input shaft is driven at high speed and low torque.

[0004] To achieve this, a first aspect of the utility model proposes a transmission mechanism, including: a drive shaft, a receiving member rotating around a rotation axis coaxial with the drive shaft, a main planetary gear set, which includes a first input member, a second input member and an output member rigidly connected to the rotating receiving member to rotate therewith, and a kinematic link between the drive shaft and the first input member of the main planetary gear set, with a transmission ratio equal to 1. The transmission mechanism further includes an auxiliary planetary gear set, which includes a first input member, a second input member and an output member, the first input member of the main planetary gear set is rigidly connected to the first input member of the auxiliary planetary gear set to rotate therewith, and the second input member of the main planetary gear set is rigidly connected to the output member of the auxiliary planetary gear set to rotate therewith.

[0005] This coaxial arrangement allows the force to be transmitted from the drive shaft to the input member of the auxiliary planetary gear set with lower mechanical losses, and simplifies the positioning of the input member rigidly connected to the drive shaft, such as a motor coaxial with the transmission mechanism.

[0006] This mechanism enables a high transmission ratio to be obtained. In practice, the transmission ratio between the drive shaft and the rotating receiving member of this mechanism is greater than 15, preferably greater than 50, and preferably greater than 100.

[0007] According to an embodiment, the first input member of the main planetary gear set is the sun gear, the second input member of the main planetary gear set is the planet carrier, the output member of the main planetary gear set is the ring gear, the second input member carries a row of pinion gears meshing with the first input member and the output member, and the first input member of the auxiliary planetary gear set is the sun gear, the second input member of the auxiliary planetary gear set is the ring gear, the output member of the auxiliary planetary gear set is the planet carrier carrying a row of pinion gears, and the pinion gears mesh with the first input member and the second input member.

[0008] According to an embodiment, in absolute value, the ratio K of the number of teeth of the ring gear of the auxiliary planetary gear set to the number of teeth of the sun gear of the auxiliary planetary gear set aux , and the ratio K of the number of teeth of the ring gear of the main planetary gear set to the number of teeth of the sun gear of the main planetary gear set main satisfy the following inequality:

[0009] 1.5 ≤ |K aux | ≤ 9

[0010] 1.5 ≤ |K main | ≤ 9

[0011]

[0012] According to an embodiment, the first input member of the main planetary gear set is the sun gear, the second input member of the main planetary gear set is the ring gear, and the output member of the main planetary gear set is the planet carrier carrying a row of pinion gears, and the pinion gears mesh with the first input member and the second input member; and the first input member of the auxiliary planetary gear set is the sun gear, the second input member of the auxiliary planetary gear set is the ring gear, and the output member of the auxiliary planetary gear set is the planet carrier having two rows of pinion gears, carrying the first row of pinion gears meshing with the first input member and the second row of pinion gears meshing with the first row of pinion gears and the second input member.

[0013] According to an embodiment, the second input member of the auxiliary planetary gear set is fixed to prevent rotation.

[0014] According to an embodiment, the transmission mechanism includes a housing containing the main planetary gear set and the auxiliary planetary gear set.

[0015] According to one embodiment, the rotary receiving member is an output differential that drives two output shafts coaxial with the main axis of two planetary gear sets, and one of the two output shafts passes through the planetary gear set of the transmission mechanism. This arrangement requires complex components, especially the motor and the rotating main shaft of the centrally hollow planetary gear set. It allows the transmission mechanism to be more compact. Alternatively, the rotary receiving member is a drive shaft for driving the wheels, via a constant velocity joint, or a ring gear, or a splined shaft for a clutch actuator, or a shaft provided with a power take-off interface, where applicable.

[0016] Another aspect of the present invention relates to a drive unit including a rotary electric machine and a transmission mechanism, the rotary electric machine being coaxial with the drive shaft. The drive unit can be a drive unit for driving a power take-off device or a load, or a propulsion unit for a motor vehicle. In particular, the rotary electric machine is axially positioned on the side opposite to the receiving member of the input member of the auxiliary planetary gear set.

[0017] Preferably, the drive shaft is directly driven by the rotary electric machine.

[0018] Preferably, the rotary electric machine includes a rotor.

[0019] Advantageously, the receiving member can be the input member of an output differential that distributes torque between two output half shafts, one of the output half shafts passing through the main planetary gear set, the auxiliary planetary gear set, the drive shaft, and the rotor of the rotary electric machine. More specifically, the main planetary gear set, the auxiliary planetary gear set, the drive shaft, and the rotor of the rotary electric machine have tubular portions. This makes the transmission unit more compact.

[0020] Advantageously, the output half shaft can pass through the tubular portions of the main planetary gear set, the auxiliary planetary gear set, the drive shaft, and the rotor of the rotary electric machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] With reference to the accompanying drawings, other features and advantages of the present invention will become apparent by reading the following description.

[0022] Figure 1 A vehicle powertrain including a propulsion unit and a transmission mechanism according to a first embodiment of the present invention is shown.

[0023] Figure 2 A vehicle powertrain including a propulsion unit and a transmission mechanism according to a second embodiment of the present invention is shown.

[0024] Figure 3 A vehicle powertrain including a propulsion unit and a transmission mechanism according to a third embodiment of the present invention is shown.

[0025] Figure 4 A vehicle powertrain including a propulsion unit and a transmission mechanism according to a fourth embodiment of the present invention is shown.

[0026] For greater clarity, in all the figures, elements having the same or similar functions are identified by the same reference numerals. Detailed Description

[0027] Figure 1 There is shown a driveline 10 of a vehicle, which is more specifically (but not exclusively) for a motorized personal transporter and occupies a reduced amount of space within the driveline, which includes a receiving member 12 driven by a drive unit 14, which in this case is a propulsion unit, and drives at least one output wheel 16.

[0028] The propulsion unit 14 includes a rotary electric machine 18 and a transmission mechanism 20 that kinematically connects the rotary electric machine 18 to the receiving member 12 of the vehicle.

[0029] The transmission mechanism 20 has a speed reduction function. Further, in order to give the vehicle good performance in terms of speed and torque while allowing the rotary electric machine 18 to operate within a favorable speed and torque operating range, the transmission mechanism 20 is designed to enable a transmission ratio to be established between the electric machine 18 and the receiving member 12 of the vehicle.

[0030] To this end, the transmission mechanism 20 includes a drive shaft 22 directly driven by the rotary electric machine 18, an auxiliary planetary gear set 24 connected to the drive shaft 22 by a direct connection 25, a main planetary gear set 26 connected to the auxiliary planetary gear set 24 by at least two connections between the members of the auxiliary planetary gear set 24 and the input member of the main planetary gear set 26, an output member 46 driven by the main planetary gear set 26, and a receiving member 12 constituted by an output shaft 28 and the wheel 16.

[0031] The drive shaft 22 is coaxial with the rotor 30 of the electric machine 18, the two planetary gear sets 24 and 26, and the receiving member 12 of the transmission mechanism 20 about the reference axis of the mechanism. The connection between the electric machine 18 and the auxiliary planetary gear set 24 is a direct connection.

[0032] The transmission mechanism 20 preferably includes at least one guiding bearing 11 between the electric machine 18 and the auxiliary planetary gear set 24, a guiding bearing 13 between the main planetary gear set 26 and the receiving member 12, a guiding bearing 15 at the input of the electric machine 18, and a guiding bearing 17 at the output of the receiving member 12.

[0033] In Figure 1In the embodiment, the auxiliary planetary gear set 24 is a gear set in which a first rotary input member 32 connected to the drive shaft 22 is a sun gear, a second input member 34 is an annular gear fixed to the housing 38 of the transmission mechanism 20, and a rotary output member 40 is a carrier kinematically connected to a row of planet pinions 41, and the planet pinions 41 mesh with the annular gear 34 fixed to the housing 38 and the sun gear 32. The sun gear 32 is kinematically connected to the planet pinions 41 of the auxiliary planetary gear set 24 so as to form a reduction gear set.

[0034] In Figure 1 the embodiment, the main planetary gear set 26 is a gear set in which a first rotary input member 42 rotatably connected to the drive shaft 22 and the first rotary input member 32 of the auxiliary planetary gear set 24 is a sun gear, and a second input member 44 connected to the output member 40 of the auxiliary planetary gear set 24 is a carrier kinematically connected to a row of planet pinions 45, and the planet pinions 45 mesh with the input member 32 of the auxiliary planetary gear set 24 and an annular gear constituting the rotary output member 46.

[0035] The output member 40 of the auxiliary planetary gear set 24 and the second input member 44 of the main planetary gear set 26 may form a single part, or an inseparable assembly of parts, or two different rigidly connected components such that they rotate as a whole. The diameter of the shaft supporting the planet pinions 45 of the carrier 44 is smaller than the diameter of the shaft supporting the planet pinions 41 of the carrier 40.

[0036] The rotary output member 46 of the main planetary gear set 26 is rigidly connected to the shaft 28 of the receiving member 12 to rotate therewith. The output wheel 16 is coaxial with the rotary axis of the planetary gear set 26, thus allowing optimal transmission of force, especially torque.

[0037] To set the magnitude of the overall transmission ratio of the transmission mechanism, the algebraic ratio K aux of the number of teeth ZC aux of the annular gear 34 of the auxiliary planetary gear set 24 aux to the number of teeth ZP

[0038]

[0039] However, in practice, for planetary gear sets such as those used in this first embodiment (i.e., having an annular gear, a summing gear, and a carrier having a row of planet pinions meshing with a sun gear), not all ratios K auxAll are achievable. Therefore, in order to simply determine the dimensions of the tooth sets of the ring gear, sun gear, and planet pinions, a range of limiting values is required such that:

[0040] -9 ≤ K aux ≤ -1.5

[0041] Similarly, the ratio K main of the number of teeth ZC main of the ring gear 46 to the number of teeth ZP main of the sun gear 42 is the same. The main planet gear set 26 of the same type as the auxiliary planet gear set is subject to the same constraints. Therefore:

[0042]

[0043] -9 ≤ K main ≤ -1.5

[0044] Using these given definitions and ranges of variation, the transmission ratio R of the transmission mechanism between the drive shaft 22 and the rotary output member 46 can be expressed by the following equation:

[0045]

[0046] When the two ratios K main and K aux are equal, the ratio R is theoretically infinite. By selecting a ratio K aux / K main close to 1, for example, between 0.5 and 1.5, preferably between 0.75 and 1.25, excluding values too close to 1, such as between 0.98 and 1.02, a high transmission ratio is obtained. The following table gives values that are advantageous in practice:

[0047] <![CDATA[K main > <![CDATA[K aux > <![CDATA[K aux / K main > R -3 -2.25 75％ 13 -6 -4.5 75％ 22 -9 -6.75 75％ 31 -3 -2.7 90％ 37 -6 -5.4 90％ 64 -9 -8.1 90％ 91 -3 -2.94 98％ 197 -6 -5.88 98％ 344 -9 -8.82 98％ 491 -9 -9.18 102％ -509 -6 -6.12 102％ -356 -3 -3.06 102％ -203 -8 -8.8 110％ -98 -6 -6.6 110％ -76 -3 -3.3 110％ -43 -7 -8.75 125％ -39 -6 -7.5 125％ -34 -3 -3.75 125％ -19

[0048] Figure 2 The transmission mechanism shown is different from Figure 1 the transmission mechanism shown. The main planet gear set 26 is such a gear set in which the first rotary input member 32 rigidly fixed to the drive shaft 22 and the auxiliary planet gear set 24 rotates with the first rotary input member 42 which is the sun gear, the rotary output member 46 is the planet carrier with a row of planet pinions 45, and the second rotary input member 44 is the ring gear.

[0049] In addition, in Figure 2In the embodiment, the rotating output member 40 of the auxiliary planetary gear set 24 is a planet carrier, which has two rows of pinion gears 411 and 412 meshing with each other. One row of pinion gears 411 meshes with the first input member 32, and one row of pinion gears 412 meshes with the second input member 34. The two rows of pinion gears 411 and 412 are radially offset.

[0050] As the main planetary gear set is of the same type as that in the first embodiment, the same characteristic parameter K that varies within the same range can be used main to describe:

[0051]

[0052] -9 ≤ K main ≤ -1.5

[0053] On the other hand, the auxiliary planetary gear set has two rows of pinion gears. Therefore, when the planet carrier is stationary, the rotation directions of the ring gear and the sun gear are the same. Therefore, the sign of the ratio K aux is positive:

[0054]

[0055] 1.5 ≤ K aux ≤ 9

[0056] In this configuration, the transmission ratio R of the transmission mechanism between the drive shaft 22 and the rotating output member 46 can be expressed by the following equation:

[0057]

[0058] When the denominator of the equation approaches zero, R approaches infinity. Therefore, when K aux tends to (1 - K main ). By selecting a ratio (1 - K aux ) / K main close to 1, for example, between 0.5 and 1.5, preferably between 0.75 and 1.25, excluding values too close to 1, such as between 0.98 and 1.02, a high transmission ratio is obtained.

[0059] Table 2 gives the values that are advantageous in practice:

[0060]

[0061]

[0062] Figure 3 The shown transmission mechanism 20 is different in terms of the receiving member 12 from Figure 1The transmission mechanism shown has a receiving member 12 that is the input member of an output differential 60 which distributes torque between two output half shafts 62, 64, with one of the output half shafts passing through the tubular main planetary gear set 26, the auxiliary planetary gear set 24, and the drive shaft 22 and rotor 30 of the electric machine 18. In this embodiment, the transmission mechanism includes a guide bearing 61 on the output half shaft 62 and a guide bearing 63 on the output half shaft 64.

[0063] Figure 4 The transmission mechanism 20 shown differs in terms of the receiving member from Figure 2 the transmission mechanism shown, where the receiving member is the input member of an output differential 60 which distributes torque between two output half shafts 62, 64, with one of the output half shafts passing through the tubular main planetary gear set 26, the auxiliary planetary gear set 24, and the drive shaft 22 and rotor 30 of the electric machine 18. In this embodiment, the transmission mechanism includes a guide bearing 61 on the output half shaft 62 and a guide bearing 63 on the output half shaft 64.

[0064] Of course, the examples shown in the figures and described above are provided by way of non - limiting illustration only. For the purpose of presenting further embodiments, it is expressly provided that various shown embodiments may be combined.

Claims

1. A transmission mechanism (20) comprises: - a drive shaft (22), - a receiving member (12) that rotates about a rotational axis coaxial with the drive shaft (22), - a main planetary gear set (26) that includes a first input member (42), a second input member of the main planetary gear set (26), and an output member (46), the output member being rigidly connected to the rotating receiving member (12) to rotate therewith; - a kinematic link (25) between the drive shaft (22) and the first input member (42) of the main planetary gear set (26), the transmission ratio being equal to 1; wherein the transmission mechanism (20) further includes an auxiliary planetary gear set (24), the auxiliary planetary gear set including a first rotating input member (32), a second input member of the auxiliary planetary gear set (24), and a rotating output member (40), the first input member (42) of the main planetary gear set (26) being rigidly connected to the first rotating input member (32) of the auxiliary planetary gear set (24) to rotate therewith, and the second input member of the main planetary gear set (26) being rigidly connected to the rotating output member (40).

2. The transmission mechanism (20) according to claim 1, characterized in that, The transmission ratio between the drive shaft (22) and the rotating receiving member (12) of the mechanism (20) is greater than 15.

3. The transmission mechanism (20) according to any one of claims 1 and 2, characterized in that: - the first input member (42) of the main planetary gear set (26) is a sun gear, the second input member of the main planetary gear set (26) is a planet carrier, the output member (46) of the main planetary gear set (26) is a ring gear, and the second input member of the main planetary gear set (26) carries a row of planet pinions that mesh with the first input member (42) and the output member (46); and - the first rotating input member (32) of the auxiliary planetary gear set (24) is a sun gear, the second input member of the auxiliary planetary gear set (24) is a ring gear, and the rotating output member (40) of the auxiliary planetary gear set (24) is a planet carrier that carries a row of planet pinions that mesh with the first rotating input member (32) and mesh with the second input member of the auxiliary planetary gear set (24).

4. The transmission mechanism (20) according to claim 3, characterized in that, In terms of absolute values, the ratio K of the number of teeth of the ring gear of the auxiliary planetary gear set to the number of teeth of the sun gear of the auxiliary planetary gear set aux , and the ratio K of the number of teeth of the ring gear of the main planetary gear set to the number of teeth of the sun gear of the main planetary gear set main satisfy the following inequality: 1.5≤|K aux |≤9 1.5≤|K main |≤9 5. The transmission mechanism (20) according to claim 1 or 2, characterized in that: - the first input member (42) of the main planetary gear set (26) is a sun gear, the second input member of the main planetary gear set (26) is a ring gear, and the output member (46) of the main planetary gear set (26) is a planet carrier that carries a row of planet pinions that mesh with the first input member (42) and mesh with the second input member of the main planetary gear set (26); and - The first rotating input member (32) of the auxiliary planetary gear set (24) is a sun gear, the second input member of the auxiliary planetary gear set (24) is a ring gear, and the rotating output member (40) of the auxiliary planetary gear set (24) is a planet carrier having two rows of pinion gears meshing with each other. One row of pinion gears in the two rows of pinion gears meshes with the first rotating input member (32), and the other row of pinion gears in the two rows of pinion gears meshes with the second input member of the auxiliary planetary gear set (24).

6. The drive mechanism (20) according to claim 5, characterized in that, In terms of absolute value, the ratio K of the number of teeth of the ring gear of the auxiliary planetary gear set to the number of teeth of the sun gear of the auxiliary planetary gear set aux , and the ratio K of the number of teeth of the ring gear of the main planetary gear set to the number of teeth of the sun gear of the main planetary gear set main satisfy the following inequality: 1.5≤|K aux |≤9 1.5≤|K main |≤9 7. The transmission mechanism (20) according to claim 1, characterized in that, The second input member of the auxiliary planetary gear set (24) is fixed to prevent rotation.

8. The transmission mechanism (20) according to claim 1, characterized in that, The transmission mechanism includes a housing (38) containing the main planetary gear set (26) and the auxiliary planetary gear set (24).

9. The transmission mechanism (20) according to claim 1, characterized in that, The rotation receiving member (12) is an output differential (60) that drives two output half shafts (62, 64) coaxial with the main axis of the two planetary gear sets (24, 26). One of the two output half shafts passes through the planetary gear sets (24, 26) of the transmission mechanism.

10. The transmission mechanism (20) according to claim 1, characterized in that, The rotation receiving member (12) is: - A drive shaft (28) of a drive wheel (16), via a constant velocity universal joint where applicable; - A ring gear, or - A spline shaft of a clutch actuator, or - A shaft provided with a power output interface.

11. A drive unit (14), characterized in that, The drive unit (14) includes: a rotating electric machine (18) and a transmission mechanism (20) according to any one of claims 1 to 10. The rotating electric machine (18) is coaxial with the drive shaft (22).

12. The drive unit (14) according to claim 11, characterized in that, The rotating electric machine (18) is axially positioned on the side of the first rotating input member (32) of the auxiliary planetary gear set (24) opposite to the receiving member (12).

13. The drive unit (14) according to claim 11, characterized in that, The receiving member (12) is an input member of an output differential (60) that distributes torque between two output half shafts (62, 64). One of the output half shafts passes through the main planetary gear set (26), the auxiliary planetary gear set (24), the drive shaft (22), and the rotor (30) of the rotating electric machine (18). The main planetary gear set, the auxiliary planetary gear set, the drive shaft, and the rotor of the rotating electric machine have tubular portions.

14. The drive unit (14) according to claim 13, characterized in that, The output half shaft passes through the tubular portions of the main planetary gear set, the auxiliary planetary gear set, the drive shaft, and the rotor of the rotating electric machine.

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