Single-axial transmission mechanism and associated drive assembly
The compact transmission mechanism with coaxial epicyclic gear trains addresses the bulkiness and high-torque requirements of existing systems, achieving efficient torque transmission and reduced mechanical losses.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- VALEO EMBRAYAGES SAS
- Filing Date
- 2022-12-22
- Publication Date
- 2026-06-26
AI Technical Summary
Existing transmission mechanisms for motorized vehicles are bulky and require high-torque electric motors due to insufficient gear reduction, limiting compactness and efficiency.
A compact transmission mechanism with a coaxial arrangement of main and auxiliary epicyclic gear trains, allowing high torque and low speed output, and a kinematic linkage with a speed ratio greater than 15, preferably greater than 50, to reduce mechanical losses and simplify component positioning.
Achieves high speed ratios and compactness by reducing mechanical losses, enabling efficient torque transmission with reduced mechanical complexity and motor sizing.
Smart Images
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Abstract
Description
Title of the invention: Single-axial transmission mechanism and associated drive assembly TECHNICAL FIELD OF THE INVENTION
[0001] The invention relates to a transmission mechanism, more particularly intended for driving a motorized vehicle, for example a motor vehicle, a motorcycle, a motorized personal mobility device (PMD), a vehicle for transporting persons with reduced mobility or an autonomous vehicle, or a piece of equipment, for example a power take-off of a construction vehicle or an agricultural vehicle. PRIOR TECHNOLOGY
[0002] Document EP3630521 describes a transmission mechanism comprising: a drive shaft driven by an electric motor, a driven member consisting of a differential rotating about an axis of rotation coaxial with the drive shaft, a main epicyclic gear train comprising a first input member, a second input member and an output member fixed to the rotating driven member; and a connection between the drive shaft and the first input member of the main epicyclic gear train with a speed ratio of 1. The drive of the second input member of the main epicyclic gear train is achieved via at least one idler shaft parallel to the drive shaft, in a very bulky arrangement in the axial direction, and not allowing a high speed ratio between the drive shaft and the driven member.Without sufficient gear reduction in the transmission mechanism, the electric motor must then be sized to deliver high torque, which is undesirable. Description of the invention
[0003] The invention aims to remedy the disadvantages of the prior art and to propose a compact transmission mechanism and a gear ratio which makes it possible to obtain, at the output of the mechanism, a high torque and a low drive speed, with a high speed and low torque input shaft drive.
[0004] To this end, according to a first aspect of the invention, a transmission mechanism is proposed comprising a drive shaft, a driven member rotating about an axis of rotation coaxial with the drive shaft, a main epicyclic gear train comprising a first input member, a second input member, and an output member fixed in rotation to the rotating driven member, and a kinematic linkage between the drive shaft and the first input member of the main epicyclic gear train with a speed ratio of 1. The transmission mechanism further comprises an auxiliary epicyclic gear train comprising a first input member, a second input member input and output member, the first input member of the main epicyclic train is rotationally fixed to the first input member of the auxiliary epicyclic train, and the second input member of the main epicyclic train is rotationally fixed to the output member of the auxiliary epicyclic train.
[0005] This coaxial arrangement allows the forces from the drive shaft to the input element of the auxiliary epicyclic gear train to be transmitted with a reduction of mechanical losses and simplifies the positioning of the input element attached to the drive shaft, for example an electric machine, which is coaxial with the transmission mechanism.
[0006] The mechanism makes it possible to obtain high speed ratios. In practice, the mechanism has a speed ratio between the driving shaft and the rotating driven member in a ratio greater than 15, preferably greater than 50, preferably greater than 100.
[0007] According to one embodiment, the first input member of the main epicyclic gear train is an inner planetary gear, the second input member of the main epicyclic gear train is a planet carrier and the output member of the main epicyclic gear train is a ring gear, the second input member carrying a row of planets meshing with the first input member and the output member and the first input member of the auxiliary epicyclic gear train is an inner planetary gear, the second input member of the auxiliary epicyclic gear train is a ring gear and the output member of the auxiliary epicyclic gear train is a planet carrier carrying a row of planets meshing with the first input member and the second input member.
[0008] According to one embodiment, in absolute value, the ratio Kaux of the number of teeth of the crown of the auxiliary epicyclic gear train to the number of teeth of the inner planetary gear of the auxiliary epicyclic gear train and the ratio Kprinc of the number of teeth of the crown of the main epicyclic gear train to the number of teeth of the inner planetary gear of the main epicyclic gear train satisfy the following inequalities:
[0009] 1.5 £ <9
[0010] 1.5 < <9
[0011] 0.75 <II <0.98 or 1.02 <II <1.25
[0012] According to one embodiment, the second input element of the auxiliary epicyclic gear train is fixed in rotation.
[0013] According to one embodiment, the transmission mechanism comprises a frame containing the main epicyclic gear train and the auxiliary epicyclic gear train.
[0014] According to one embodiment, the rotating receiving member is an output differential driving two coaxial output shafts with a main axis of the two epicyclic gear trains, one of the two output shafts passing through the epicyclic gear trains of the Transmission mechanism. This arrangement requires complex components, including an electric motor and a main rotation axis for the hollow epicyclic gear trains. It allows for increased compactness of the transmission mechanism. Alternatively, the rotating driven element is a wheel drive shaft, possibly via a constant velocity joint, or a ring gear, or a splined shaft for a clutch actuator, or a shaft with a power take-off interface.
[0015] According to another aspect of the invention, it relates to a drive assembly comprising a rotating electric machine and a transmission mechanism, the rotating electric machine being coaxial with the motor shaft. The drive assembly may be a drive assembly for driving a power take-off or a load, or a propulsion assembly for a motor vehicle. In particular, the rotating electric machine is positioned axially on one side of the input member of the auxiliary epicyclic gear train opposite the driven member. BRIEF DESCRIPTION OF THE FIGURES
[0016] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figures.
[0017] [Fig.1] Fig.1 illustrates a vehicle drive train comprising a propulsion assembly and a transmission mechanism according to a first embodiment of the invention.
[0018] [Fig.2] Fig.2 illustrates a vehicle drive train comprising a set of propulsion and a transmission mechanism according to a second embodiment of the invention.
[0019] [Fig. 3] Fig. 3 illustrates a vehicle drive train comprising a set of propulsion and a transmission mechanism according to a third embodiment of the invention.
[0020] [Fig.4] [Fig.4] illustrates a vehicle drive train comprising a set of propulsion and a transmission mechanism according to a fourth embodiment of the invention.
[0021] For clarity, functionally identical or similar elements are identified by identical reference numerals throughout the figures, DETAILED description of embodiments
[0022] Figure 1 illustrates a drive train 10 of a vehicle intended more particularly, although not exclusively, for a motorized personal mobility device, having a reduced overall volume within the drive train, the latter comprising a receiving element 12 driven by a drive assembly 14, in this case a propulsion assembly, and driving at least one wheel of Exit 16.
[0023] This propulsion assembly 14 comprises a rotating electric machine 18 and a transmission mechanism 20 kinematically linking the rotating electric machine 18 to the receiving organ 12 of the vehicle.
[0024] The transmission mechanism 20 has a speed reduction function. Furthermore, in order to give the vehicle good performance in terms of speed and torque while limiting losses, while allowing the rotating electric machine 18 to operate within a favorable speed and torque operating range, the transmission mechanism 20 is intended to establish a speed ratio between the electric machine 18 and the vehicle's receiving component 12.
[0025] For this purpose, the transmission mechanism 20 comprises a drive shaft 22 driven directly by the rotating electric machine 18, an auxiliary epicyclic gear train 24 linked to the drive shaft 22 by a direct link 25, a main epicyclic gear train 26 linked to the auxiliary epicyclic gear train 24 by at least two links between components of the auxiliary epicyclic gear train 24 and input components of the main epicyclic gear train 26, an output component 46 driven by the main epicyclic gear train 26 and a receiving component 12 consisting of an output shaft 28 and a wheel 16.
[0026] The drive shaft 22 is coaxial with the rotor 30 of the electric machine 18, with the two epicyclic gear trains 24 and 26, and with the driven member 12 of the transmission mechanism 20, along a reference axis of the mechanism. The connection between the electric machine 18 and the auxiliary epicyclic gear train 24 is direct.
[0027] The transmission mechanism 20 preferably includes at least one guide bearing 11 between the electric machine 18 and the auxiliary epicyclic gear train 24, a guide bearing 13 between the main epicyclic gear train 26 and the receiving member 12, a guide bearing 15 at the input of the electric machine 18 and a guide bearing 17 at the output of the receiving member 12.
[0028] The auxiliary epicyclic gear train 24 is, in the embodiment of [Fig. 1], a train in which the first rotating input member 32, linked to the drive shaft 22, is an internal planetary gear, the second input member 34 is a ring gear fixed to the frame 38 of the transmission mechanism 20 and the rotating output member 40 is a planet carrier kinematically linked to a row of planets 41 meshing with the ring gear 34 fixed to the frame 38 and the internal planetary gear 32. The internal planetary gear 32 is kinematically linked to the planets 41 of the auxiliary epicyclic gear train 24 to form a speed reducer.
[0029] In the embodiment of [Fig. 1], the main epicyclic gear train 26 is a train in which the first rotating input member 42, rotationally linked to the drive shaft 22 and to the first rotating input member 32 of the auxiliary epicyclic gear train 24, is an internal planetary gear, and the second input member 44 is linked to the output member 40 of the train auxiliary epicyclic gear 24, is a planet carrier s kinematically linked to a row of satellites 45 meshing with the input member 32 of the auxiliary epicyclic gear train 24 and with a toothed ring constituting the rotating output member 46.
[0030] The output member 40 of the auxiliary epicyclic gear train 24 and the second input member 44 of the main epicyclic gear train 26 may form a single part, an assembly of joined parts, or two separate assemblies fixed to each other for rotation. The support shafts of the satellites 45 of the planet carrier 44 are mounted on a diameter smaller than the mounting diameter of the support shafts of the satellites 41 of the planet carrier 40.
[0031] The rotating output member 46 of the main epicyclic gear train 26 is rotationally fixed to the shaft 28 of the receiving member 12. The output wheel 16 is coaxial with the axis of rotation of the epicyclic gear train 26 to allow optimal transmission of forces, in particular torque forces.
[0032] To dimension the overall transmission ratio of the transmission mechanism, the algebraic ratio Kaux of the number of teeth ZCaux of the ring gear 34 to the number of teeth ZPaux of the inner planet gear 32 of the auxiliary epicyclic gear train 24 is observed, taking the positive sign if the directions of rotation of the ring gear and the inner planet gear are identical when the planet carrier is at rest and negative in other cases:
[0033] r _ ZÇ™ ^aux vp s—1 aux
[0034] In practice, however, not all values of the Kaux ratio are achievable for epicyclic gear trains such as those used in this first embodiment, namely with a ring gear, an inner planet gear, and a planet carrier with a single row of planets meshing with the ring gear and the inner planet gear. Therefore, for simple dimensioning of the teeth of the ring gear, the inner planet gear, and the planets, it is desirable to limit the values to a range such that:
[0035] -9^Kaux< -1.5
[0036] Similarly, the same ratio Kprinc of the number of teeth ZCprinc of the crown 46 to the number of teeth ZPprinc of the inner planetary gear 42 is observed with the same constraints for the main epicyclic gear train 26, which is of the same type as the auxiliary epicyclic gear train, which allows us to write:
[0037] - _ princ” 7p . r prmc
[0038] -9 < K princ<-1.5
[0039] Given these definitions and ranges of variation, the speed ratio R of the transmission mechanism, between the drive shaft 22 and the rotating output member 46, is expressed by the equation:
[0040] „ _ Kprincx^
[0041] When the two ratios Kprinc and Kaux are equal, the ratio R is theoretically infinite. By choosing a Kaux / Kprinc ratio close to 1, for example between 0.5 and 1.5, and preferably between 0.75 and 1.25, while excluding values too close to 1, for example between 0.98 and 1.02, high transmission ratios are obtained. The following table gives some practically useful sizings: TZ" kprinc TZ" ^-aux Kaux / Kprinc 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
[0042] The transmission mechanism shown in [Fig.2] differs from that of [Fig.1] at the level of the main epicyclic gear train 26, which is a gear train in which the first rotating input member 42, fixed in rotation to the drive shaft 22 and the first rotating input member 32 of the auxiliary epicyclic gear train 24, is an internal planetary gear, the rotating output member 46 is a planet carrier with one row of planets 45, and the second rotating input member 44 is a toothed ring.
[0043] Furthermore, in the embodiment of [Fig. 2], the rotating output member 40 of the auxiliary epicyclic gear train 24 is a planet carrier with two rows of planets 411 and 412 meshing with each other, the row of planets 411 meshing with the first input organ 32 and the row of satellites 412 meshing with the second input organ 34. The two rows of satellites 411, 412 are radially offset.
[0044] Insofar as the main epicyclic gear train is of the same type as in the first embodiment, it can be described by the same characteristic quantity K princ evolving in the same domain:
[0045] _ ^prine princ ““ ' zp . z prmc
[0046] -9 <Kprinc< -1,5
[0047] The auxiliary epicyclic gear train has two rows of satellites so that, when the planet carrier is stopped, the directions of rotation of the ring gear and the inner planet gear are identical, which gives a positive sign to the Kaux ratio:
[0048] -ZC™ ^to the 7 p to
[0049] 1.5<^m;v<9
[0050] In this configuration, the speed ratio R of the transmission mechanism, between the drive shaft 22 and the rotating output member 46, is expressed by the equation:
[0051] R _ (
[0052] R tends towards infinity when the denominator of the equation tends towards zero, that is, when Kaux tends towards (1-Kprinc). By choosing a ratio (1-Kaux) / Kprinc close to 1, for example between 0.5 and 1.5, and preferably between 0.75 and 1.25, while excluding values too close to 1, for example between 0.98 and 1.02, high transmission ratios are obtained. Table 2 illustrates some practically useful sizings: Kprinc Kaux (1-Kaux) / Kprinc R -1.5 2.875 125% 13 -4 6 125% 25 -6 8.5 125% 35 -1.5 2.65 110% 27 -4 5.4 110% 55 -7 8.7 110% 88 -2 3.04 102% 153 -4 5.08 102% 255 -7.5 8.65 102% 433 -7.5 8.35 98% -416 -4 4.92 98% -245 -2 2.96 98% -147 -8.5 8.65 90% -86 -4 4.6 90% -45 -1.5 2.35 90% -23 -9 7.75 75% -30 -4 4 75% -15 -1.5 2.125 75% -8
[0053] The transmission mechanism 20 shown in [Fig. 3] differs from that of [Fig. 1] at the level of the receiving member 12, which is an input member of an output differential 60 distributing the torque between two output half-shafts 62, 64, one of which passes through the main epicyclic gear train 26, the auxiliary epicyclic gear train 24, and the drive shaft 22 and rotor 30 of the electric machine 18, which are tubular. 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.
[0054] The transmission mechanism 20 shown in [Fig. 4] differs from that of [Fig. 2] at the level of the receiving member, which is an input member of an output differential 60 distributing the torque between two output half-shafts 62, 64, one of which passes through the main epicyclic gear train 26, the auxiliary epicyclic gear train 24, and the drive shaft 22 and rotor 30 of the electric machine 18, which are tubular. 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.
[0055] Naturally, the examples shown in the figures and discussed above are given by way of illustration only and are not intended to be limiting. It is explicitly intended that the different embodiments illustrated can be combined to propose others.
Claims
1. Demands Drive assembly (14) comprising: a rotating electrical machine (18) and a transmission mechanism (20) comprising: - a drive shaft (22), - a receiving element (12) rotating around a rotation axis (28) coaxial with the motor shaft (22), - a main epicyclic gear train (26) comprising a first input element (42), a second input element (44) and an output element (46) fixed in rotation to the rotating receiving element (12); and - a kinematic link (25) between the drive shaft (22) and the first input element (42) of the main epicyclic train (26) with a speed ratio equal to 1; the rotating electrical machine (18) being coaxial with the motor shaft (22), in which the transmission mechanism (20) further comprises an auxiliary epicyclic gear train (24) having a first input member (32), a second input member (34) and an output member (40), in that the first input member (42) of the main epicyclic gear train (26) is rotationally fixed to the first input member (32) of the auxiliary epicyclic gear train (24), and in that the second input member (44) of the main epicyclic gear train (26) is rotationally fixed to the output member (40) of the auxiliary epicyclic gear train (24), and in which the first input member (42) of the main epicyclic gear train (26) is an inner planetary gear, the second input member (44) of the main epicyclic gear train (26) is a planet carrier and the output member (46) of the main epicyclic gear train (26) is a ring gear, the second input member (44) carrying a row of planetary gears (45) meshing with the first input member (42) and the output member (46) and; the first input member (32) of the auxiliary epicyclic gear train (24) is an inner planetary gear, the second input member (34) of the auxiliary epicyclic gear train (24) is a ring gear and the output member (40) of the auxiliary epicyclic gear train (24) is a planet carrier carrying a row of planets (41) meshing with the first input member (32) and the second input member (34), characterized in that the support axes of the satellites (45) of the satellite carrier (44) of the main epicyclic gear train (26) are implanted on a diameter smaller than the implantation diameter of the support axes of the satellites (41) of the satellite carrier s (40) of the auxiliary epicyclic gear train (24).
2. Drive assembly (14) according to claim 1, characterized in that the mechanism (20) has a speed ratio between the drive shaft (22) and the rotating receiving member (12) in a ratio greater than 15, preferably greater than 50, preferably greater than 100.
3. Transmission mechanism (20) according to claim 1 or 2, characterized in that, in absolute value, the ratio Kaux of the number of teeth of the crown gear of the auxiliary epicyclic gear train to the number of teeth of the inner planet gear of the auxiliary epicyclic gear train and the ratio Kprinc of the number of teeth of the crown gear of the main epicyclic gear train to the number of teeth of the inner planet gear of the main epicyclic gear train satisfy the following inequalities: 1.5 < 9, 1.5 < 9, 0.75 < 1.02 < 1.02 < 1.25
4. Drive assembly (14) according to any one of claims 1 to 3, characterized in that the second input member (34) of the auxiliary epicyclic gear train (24) is fixed in rotation.
5. Drive assembly (14) according to any one of the preceding claims, characterized in that it comprises a frame (38) containing the main epicyclic gear train (26) and the auxiliary epicyclic gear train (24).
6. Drive assembly (14) according to any one of claims 1 to 5, characterized in that the rotating receiving member (12) is an output differential (60) driving two output shafts (62,64) coaxial with a main axis (22) of the two epicyclic trains (24,26), one of the two output shafts passing through the epicyclic trains (24, 26) of the transmission mechanism.
7. Drive assembly (14) according to any one of claims 1 to 6, characterized in that the rotating receiving member (12) is: - a drive shaft (28) of a wheel (16), optionally via a constant velocity joint; a toothed crown, or a splined shaft for a clutch actuator, or a shaft with an interface for a power take-off.
8. Drive assembly (14) according to any one of the preceding claims, characterized in that the rotating electric machine (18) is positioned axially on one side of the input member (32) of the auxiliary epicyclic gear train (24) opposite the receiving member (12).