Electric motor reduction system

Abstract

The present invention relates to a reduction system (100), associated with an electric motor (10) and a pulley (20), comprising at least two epicyclic gear trains (110, 120), characterized in that at least two epicyclic gear trains (110, 120) have a common ring gear (130). Figure for the abstract: Fig. 2.

Description

Title of the invention: Electric motor reduction system

[0001] The present invention relates to a mechanical reduction system for an electric motor. The electric motor associated with the reduction system is a motor that can control a machine that is at least partially electrical, and for example, a mobility device such as an electric vehicle or an electric bicycle.

[0002] Reduction systems incorporating an epicyclic gear train are already known. The role of these mechanical reducers is to modify the speed ratio and torque between the input and output shafts of the mechanism controlling a machine. This type of reducer is located in the pulley of an electric motor and thus allows the torque required by the machine driven by the electric motor to be adjusted.

[0003] For example, such a reduction gear includes a primary pinion, also called a sun gear, a ring gear, and secondary pinions called planet gears, which mesh between the primary pinion and the ring gear. The planet gears are held by a frame called a planet carrier. The primary pinion, ring gear, and planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the electric motor. The secondary pinions each have a different axis of revolution, equally spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis of the electric motor. In this type of system, the ring gear is fixed, and the planet carrier constitutes the output shaft of the device, rotating in the same direction as the primary pinion.

[0004] One disadvantage of these reducers is that they have a reduced reduction ratio range, for, moreover, limited compactness.

[0005] The present invention therefore aims to overcome one or more of the drawbacks of prior art systems by proposing an improved electric motor reduction system.

[0006] For this purpose the present invention proposes a reduction system, associated with an electric motor and a pulley, comprising at least two epicyclic trains, characterized in that at least two epicyclic trains have a common ring.

[0007] The ring gear driven by the first epicyclic gear train then drives the second epicyclic gear train. Since this second epicyclic gear train is also driven by the motor, the difference in the two drive speeds applied to the second epicyclic gear train creates a reduction in rotational speed. This allows for an increase in the reduction ratio.

[0008] According to one embodiment of the invention, the common ring allows an increase in the reduction ratio of a value greater than 50.

[0009] According to one embodiment of the invention, a first epicyclic gear train comprises a first fixed satellite carrier rotating relative to the motor.

[0010] According to one embodiment of the invention, a first epicyclic gear train comprises a first primary pinion fixed to a shaft of the motor, this first primary pinion fixed to the shaft meshes with a first secondary pinion of the first epicyclic gear train, the first planet carrier being in rotation relative to the first secondary pinion by means of bearings.

[0011] According to one embodiment of the invention, a second epicyclic train is following the first epicyclic train, downstream of the motor, this second epicyclic train includes a second satellite carrier free to rotate relative to the motor.

[0012] According to one embodiment of the invention, a second satellite carrier is fixed in rotation relative to a pulley.

[0013] According to one embodiment of the invention, the second satellite carrier is fixed in rotation relative to a front plate of the pulley.

[0014] The invention also relates to a motor assembly comprising an electric motor and a pulley incorporating a reduction system according to the invention.

[0015] The invention also relates to the use of the reduction system according to the invention in a mobility device.

[0016] The invention also relates to the use of the motor assembly according to the invention in a mobility device.

[0017] Other objects, features and advantages of the invention will be better understood and will become more apparent upon reading the description given below, with reference to the accompanying figures, given by way of example and in which:

[0018] - [Fig. 1] is an external view of a motor and pulley incorporating a system reducer according to the invention,

[0019] - [Fig. 2] is a schematic representation of a cross-sectional view of half of a reduction system according to the invention.

[0020] Fig. 1 represents a motor assembly comprising an electric motor 10 and a pulley 20 incorporating a reduction system 100 according to the invention.

[0021] The motor assembly 1 is for example intended to be installed in a mobility device such as an electric vehicle or an electric-assisted bicycle.

[0022] As illustrated [Fig.2] assembly 1 motor comprises a motor shaft 30.

[0023] The electric motor 10 is a standard electric motor comprising a rotor 12 and a stator 11. In one embodiment, the stator is a wound or permanent magnet stator. In the example described [Fig. 2], the stator is a wound stator.

[0024] The motor 10 is integrated into a motor housing 13.

[0025] Downstream of the motor is a pulley 20. A rear motor plate 14 or bearing is located between the electric motor 10 and the pulley 20. This rear plate 14 is mounted in rotation on the motor shaft 30 via a first bearing 31. The pulley 20 is mounted in rotation relative to the shaft 30 via a second bearing 32 located at the front part 21 of the pulley 20. The front part 21 being the part 21 located downstream relative to the electric motor 10.

[0026] According to one embodiment of the invention, the reduction system 100 concerned by the invention is disposed in the pulley 20. More precisely, the pulley 20 and the reduction system 100 are disposed coaxially with respect to each other, the pulley being disposed around the reduction system 100, outside the reduction system 100. The outside being defined with respect to the motor shaft 30 which is located inside the reduction system 100.

[0027] In the context of the invention, the reduction system 100 comprises at least two epicyclic gear trains 110, 120 with a common ring gear 130. According to one embodiment of the invention, the reduction system 100 comprises two epicyclic gear trains 110, 120 with a common ring gear 130. According to one embodiment of the invention, the reduction system 100 comprises two epicyclic gear trains 110, 120 with a common ring gear 130, and one of the two epicyclic gear trains has a fixed element relative to the system. In this system, the ring gear is thus driven by the first epicyclic gear train, which then drives the second epicyclic gear train. Since this second epicyclic gear train is also driven by the motor, the difference in the two drive speeds applied to the second epicyclic gear train creates a reduction in the rotational speed. This makes it possible to increase the reduction ratio.

[0028] According to one embodiment of the invention, a first epicyclic gear train 110 comprises a first planet carrier 111. This first planet carrier 111 is fixed in rotation relative to the rear plate 14 of the motor. The first epicyclic gear train 110 also comprises a first primary gear 112 fixed to the shaft 30 of the motor. The first primary gear 112 fixed to the shaft 30 meshes with a first secondary gear 113 of the first epicyclic gear train 110. The first secondary gear 113 rotates about its own axis but does not rotate about the axis of the shaft 30.

[0029] A second epicyclic gear train 120 is arranged on the same principle as the first epicyclic gear train 110, following the first epicyclic gear train, downstream of the motor 10. This second epicyclic gear train 120 includes a second planet carrier 121. This second planet carrier 121 is fixed against rotation with respect to the pulley (20). More precisely, this second planet carrier 121 is fixed against rotation with respect to the front plate 21 of the pulley. The front plate 21 of the pulley is the plate arranged radially at the front end of the pulley 20. The front end is so named in contrast to the rear end, which is the one located on the electric motor side. 10. This second epicyclic gear train 120 also includes a second primary gear 122 fixed to the motor shaft 30. This second primary gear 122, fixed to the shaft, meshes with a second secondary gear 123 of the second epicyclic gear train 120. The second planet carrier 121 rotates relative to the second secondary gear 123 via a fourth bearing 34.

[0030] In the context of the invention, the crown 130 is driven, in an opposite direction of rotation B with respect to the direction of rotation A of the shaft 30, by the first secondary pinion 113, and then drives the second secondary pinion 123.

[0031] In the context of the invention, the crown 130 is internally toothed so that it can mesh with the toothed pinions as well.

[0032] The assembly is arranged so that, during operation, the electric motor drives the shaft 30 in rotation in direction A. The shaft 30 drives the first primary gear 112, which in turn drives the first secondary gear 113 of the first epicyclic gear train 110. This first secondary gear 113 drives the ring gear 130 in a direction B, which is the opposite direction of rotation to that of shaft 30 in direction A. The ring gear 130 then drives the second secondary gear 123. Since the second secondary gear 123 is also driven by the second primary gear 113, the difference in the two drive speeds applied to the second secondary gear 123 reduces the rotational speed of the gear 123 around the shaft 30. This allows for an increase in the reduction ratio to a value greater than 50.According to one embodiment of the invention, there is an increase in the reduction ratio of a value between 50 and 100.

[0033] The second satellite carrier 121 then drives the pulley 20 in rotation 38, 40.

[0034] The pulley then transmits the movement via a belt to a machine of, for example, an electric bicycle or an electric vehicle.

[0035] The invention also relates to the use of the reduction system 100 according to the invention in a mobility device of the type electric vehicle or electric assisted bicycle.

[0036] The scope of the present invention is not limited to the details given above and allows for embodiments in many other specific forms without departing from the field of application of the invention. Therefore, the present embodiments should be considered by way of illustration and may be modified without, however, departing from the scope defined by the claims.

Claims

Demands

1. Reduction system (100), associated with an electric motor (10) and a pulley (20), comprising at least two epicyclic gear trains (110, 120), characterized in that the at least two epicyclic gear trains (110, 120) have a common ring gear (130), a first epicyclic gear train (110) comprising a first planet carrier (111) fixed in rotation relative to the motor (10).

2. Reduction system (100), according to claim 1, wherein the common ring allows an increase in the reduction ratio of a value greater than 50.

3. Reduction system (100) according to any one of claims 1 to 2, wherein a first epicyclic gear train (110) comprises a first primary pinion (112) fixed to a shaft (30) of the motor, this first primary pinion (112) fixed to the shaft (30) meshes with a first secondary pinion (113) of the first epicyclic gear train (110), the first planet carrier (111) being in rotation relative to the first secondary pinion (113) via bearings (33).

4. Reduction system (100) according to any one of claims 1 to 3, wherein a second epicyclic gear train (120) is following the first epicyclic gear train, downstream with respect to the motor (10), this second epicyclic gear train (120) has a second planetary carrier (121) free to rotate with respect to the motor (10).

5. Reduction system (100) according to any one of claims 1 to 4, wherein a second planet carrier (121) is fixed in rotation relative to a pulley (20).

6. Reduction system (100) according to any one of claims 4 to 5, wherein the second planet carrier (121) is fixed in rotation relative to a plate (21) in front of the pulley (20).

7. Motor assembly (1) comprising an electric motor (10) and a pulley (20) incorporating a reduction system (100) according to any one of claims 1 to 6.

8. Use of the reduction system (100) according to any one of claims 1 to 6 in a mobility device.

9. Use of the motor assembly (1) according to claim 7 in a mobility device.

Images