Two-speed electric axle drive system

Abstract

The present invention provides a two-speed electric bridge drive system, which includes two clutches and multiple gears, a first gear (G1) is arranged on a motor shaft, a second gear (G2), a fourth gear (G4) and a first clutch (C1) are arranged on a first shaft (S1), a third gear (G3), a fifth gear (G5), a sixth gear (G6) and a second clutch (C2) are arranged on a second shaft (S2), a seventh gear (G7) is connected to a housing of a differential, the first gear is meshed with the second gear, the second gear is meshed with the third gear, the fourth gear is meshed with the fifth gear, the sixth gear is meshed with the seventh gear, the first clutch (C1) controls the connection between the second gear (G2) and the first shaft (S1), and the second clutch (C2) controls the connection between the third gear (G3) and the second shaft (S2). The electric bridge drive system according to the present invention uses three-stage gear transmission in both gears, can obtain a larger transmission ratio and does not need to change the rotation direction of the motor when the gear is switched.

Description

Technical Field

[0001] The present invention relates to the field of motor vehicles, in particular to the field of vehicle transmissions, especially to an electric bridge drive system in a pure electric vehicle or a hybrid electric vehicle, and more specifically to a two-speed electric bridge drive system. Background Art

[0002] For electric vehicles, including pure electric vehicles and hybrid (oil-electric hybrid) vehicles, their electric drive modes include central motor drive and wheel hub motor drive. A common layout of the central motor drive system is also called an eAxle drive system.

[0003] Figures 1 to 4 Two two-speed electric bridge drive systems are shown, both of which include a motor E, a differential D, two clutches (a first clutch C1 and a second clutch C2), and seven gears (G1 to G7).

[0004] First, let’s introduce Figure 1 and Figure 2 The first type of bridge drive system is shown.

[0005] In this system, the rotor of the motor E is connected to the motor shaft Se in a torsion-proof manner (not relatively rotatable), and the motor shaft Se is integrated with the input shaft Si of the transmission, that is, the motor shaft Se and the input shaft Si are actually one shaft, and this integrated shaft is also called the main shaft, which is supported by three bearings installed in the transmission housing. A first shaft S1 and a second shaft S2 are arranged parallel to the main shaft and offset relative to the main shaft in the radial direction of the main shaft. The two output half shafts Sd of the differential D are also arranged parallel to the main shaft and offset relative to the main shaft.

[0006] The main shaft is provided with a first gear G1 and a third gear G3, the first shaft S1 is provided with a first clutch C1, a second gear G2 and a fifth gear G5, the second shaft S2 is provided with a second clutch C2, a fourth gear G4 and a sixth gear G6, and the seventh gear G7 is connected to the housing of the differential D in a torsionally fixed manner.

[0007] The second gear G2 is connected to the driving part of the first clutch C1 in a torsion-proof manner, and the driven part of the first clutch C1 is connected to the first shaft S1 in a torsion-proof manner. When the first clutch C1 is disengaged, no torque is transmitted between the second gear G2 and the first shaft S1; when the first clutch C1 is engaged, the second gear G2 is connected to the first shaft S1 in a torsion-proof manner.

[0008] The driven part of the second clutch C2 is connected to the second shaft S2 in a torsion-proof manner, and the fourth gear G4 is connected to the active part of the second clutch C2 in a torsion-proof manner. When the second clutch C2 is disengaged, no torque is transmitted between the fourth gear G4 and the second shaft S2; when the second clutch C2 is engaged, the fourth gear G4 is connected to the second shaft S2 in a torsion-proof manner.

[0009] The first gear G1 meshes with the second gear G2 , the third gear G3 meshes with the fourth gear G4 , the seventh gear G7 meshes with the sixth gear G6 , and the seventh gear G7 also meshes with the fifth gear G5 .

[0010] When the first clutch C1 is in the engaged state and the second clutch C2 is in the disengaged state, the transmission is in the first gear. At this time, the power transmission path is: main shaft, first gear G1, second gear G2, first clutch C1, first shaft S1, fifth gear G5, seventh gear G7 to differential D. The number of teeth of the seven gears G1 to G7 are defined as Z1, Z2, Z3, Z4, Z5, Z6 and Z7 respectively. In the first gear, the transmission ratio of the transmission is Z7 / Z5×Z2 / Z1.

[0011] When the first clutch C1 is in the disengaged state and the second clutch C2 is in the engaged state, the transmission is in the second gear. At this time, the power transmission path is: main shaft, third gear G3, fourth gear G4, second clutch C2, second shaft S2, sixth gear G6, seventh gear G7 to differential D. In the second gear, the transmission ratio of the transmission is Z7 / Z6×Z4 / Z3.

[0012] Next, let’s introduce Figure 3 and Figure 4 The second bridge drive system is shown.

[0013] In this system, the rotor of the motor E is connected to the motor shaft Se in a rotationally fixed manner. A first shaft S1 and a second shaft S2 are arranged parallel to the motor shaft Se and offset relative to the motor shaft Se in the radial direction of the motor shaft Se. The two output half shafts Sd of the differential D are also arranged parallel to the motor shaft Se and offset relative to the motor shaft Se.

[0014] The motor shaft Se is provided with a first gear G1, the first shaft S1 is provided with a second gear G2, a third gear G3, a first clutch C1, a second clutch C2 and a fifth gear G5, the second shaft S2 is provided with a fourth gear G4 and a sixth gear G6, and the seventh gear G7 is connected to the housing of the differential D in a torsionally fixed manner.

[0015] The active parts of the first clutch C1 and the second clutch C2 are both torsionally connected to the first shaft S1, the driven part of the first clutch C1 is sleeved on the outer periphery of the first shaft S1 and torsionally connected to the third gear G3, and the driven part of the second clutch C2 is sleeved on the outer periphery of the first shaft S1 and torsionally connected to the fifth gear G5.

[0016] When the first clutch C1 is disengaged, no torque is transmitted between the third gear G3 and the first shaft S1; when the first clutch C1 is engaged, the third gear G3 is connected to the first shaft S1 in a torsion-proof manner. When the second clutch C2 is disengaged, no torque is transmitted between the fifth gear G5 and the first shaft S1; when the second clutch C2 is engaged, the fifth gear G5 is connected to the first shaft S1 in a torsion-proof manner.

[0017] The first gear G1 meshes with the second gear G2 , the third gear G3 meshes with the fourth gear G4 , the seventh gear G7 meshes with the sixth gear G6 , and the seventh gear G7 also meshes with the fifth gear G5 .

[0018] When the first clutch C1 is in the engaged state and the second clutch C2 is in the disengaged state, the transmission is in the first gear. At this time, the power transmission path is: motor shaft Se, first gear G1, second gear G2, first shaft S1, first clutch C1, third gear G3, fourth gear G4, second shaft S2, sixth gear G6, seventh gear G7 to differential D. In the first gear, the transmission ratio of the transmission is Z7 / Z6×Z4 / Z3×Z2 / Z1.

[0019] When the first clutch C1 is in the disengaged state and the second clutch C2 is in the engaged state, the transmission is in the second gear. At this time, the power transmission path is: motor shaft Se, first gear G1, second gear G2, first shaft S1, second clutch C2, fifth gear G5, seventh gear G7 to differential D. In the second gear, the transmission ratio of the transmission is Z7 / Z5×Z2 / Z1.

[0020] Each gear shift position of the first type of electric bridge drive system uses two-stage gear shifting. The transmission ratio that can be obtained in a limited space is limited. When the transmission ratio is small, the motor needs to have a large transmission torque, which increases the cost of the system. In addition, in this system, in order to obtain a larger transmission ratio, the seventh gear G7 usually has a larger diameter, which increases the system in direction X (reference Figure 2 ) dimensions (including the outer envelope boundary dimensions of the motor and each reduction gear).

[0021] The second electric bridge drive system uses a three-stage gear transmission in the first gear and a two-stage gear transmission in the second gear. Although the first gear can obtain a larger transmission ratio, the rotation direction of the motor E needs to be changed when switching between the first gear and the second gear, which increases the difficulty of system control. It is a big challenge to avoid gear damage and ensure the control accuracy of the motor E. In addition, the controller, control software and speed sensor all increase the cost of the system.

[0022] In addition, in the above two electric axle drive systems, the seventh gear G7 connected to the differential D is meshed with two gears (the fifth gear G5 and the sixth gear G6) at the same time, which puts higher requirements on the service life of the seventh gear G7 and the NVH (Noise, Vibration, Harshness) control of the system, which also increases the cost of the system. Summary of the invention

[0023] The purpose of the present invention is to overcome or at least alleviate the deficiencies of the above technical solutions and to provide a two-speed electric bridge drive system with simple control and relatively large transmission ratio.

[0024] The present invention provides an electric bridge drive system, which includes a motor, a motor shaft, a first shaft, a second shaft, a first clutch, a second clutch, a plurality of gears and a differential, wherein the motor shaft is non-rotatably connected to the rotor of the motor, wherein:

[0025] The first gear is arranged on the motor shaft, the second gear, the fourth gear and the first clutch are arranged on the first shaft, the third gear, the fifth gear, the sixth gear and the second clutch are arranged on the second shaft, and the seventh gear is connected to the housing of the differential in a non-rotatable manner.

[0026] The first gear meshes with the second gear, the second gear meshes with the third gear, the fourth gear meshes with the fifth gear, and the sixth gear meshes with the seventh gear.

[0027] When the first clutch is engaged, the second gear is non-rotatably connected to the first shaft, and when the first clutch is disengaged, the second gear is rotatably connected to the first shaft.

[0028] When the second clutch is engaged, the third gear and the second shaft are connected to each other in a non-rotatable manner, and when the second clutch is disengaged, the third gear and the second shaft are rotatable relative to each other.

[0029] In at least one embodiment, the active part of the first clutch is sleeved on the outer periphery of the first shaft, the driven part of the first clutch is non-rotatably connected to the first shaft, and the second gear is non-rotatably connected to the active part of the first clutch.

[0030] The active part of the second clutch is sleeved on the outer circumference of the second shaft, the driven part of the second clutch is non-rotatably connected to the second shaft, and the third gear is non-rotatably connected to the active part of the second clutch.

[0031] In at least one embodiment, the active portion of the first clutch is partially sleeved on the outer circumference of the driven portion of the first clutch, and the active portion of the second clutch is partially sleeved on the outer circumference of the driven portion of the second clutch.

[0032] In at least one embodiment, a diameter of the second gear is greater than a diameter of the first clutch, and a diameter of the third gear is greater than a diameter of the second clutch.

[0033] In at least one embodiment, the second gear is part of an active portion of the first clutch, and the third gear is part of an active portion of the second clutch.

[0034] In at least one embodiment, in a radial direction of the motor, the first shaft is offset and disposed at one side of the motor shaft relative to the motor shaft, and the second shaft is offset and disposed at the other side of the motor shaft relative to the motor shaft.

[0035] In at least one embodiment, the motor shaft, the first shaft, the second shaft, and the output half shaft of the differential are arranged parallel to each other.

[0036] In at least one embodiment, the number of teeth of the second gear is greater than that of the first gear, the number of teeth of the third gear is greater than that of the first gear, the number of teeth of the fifth gear is greater than that of the fourth gear, and the number of teeth of the seventh gear is greater than that of the sixth gear.

[0037] In at least one embodiment, the seven gears are all spur gears.

[0038] In at least one embodiment, when the electric bridge drive system is in a first gear, the first clutch is engaged and the second clutch is disengaged; when the electric bridge drive system is in a second gear, the first clutch is disengaged and the second clutch is engaged.

[0039] The two-speed electric bridge drive system according to the present invention uses three-stage gear transmission in both speed gears, which can obtain a larger transmission ratio and does not need to change the rotation direction of the motor when switching gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of a possible two-speed electric bridge drive system.

[0041] Figure 2 yes Figure 1 Schematic diagram of the gear meshing relationship.

[0042] Figure 3 This is a schematic diagram of another possible two-speed electric bridge drive system.

[0043] Figure 4 yes Figure 3 Schematic diagram of the gear meshing relationship.

[0044] Figure 5 It is a schematic structural diagram of a two-speed electric bridge drive system according to an embodiment of the present invention.

[0045] Figure 6 yes Figure 5 Schematic diagram of the gear meshing relationship.

[0046] Figure 7 and Figure 8 yes Figure 5 The diagram shown is a schematic diagram of the power transmission path of the electric bridge drive system in the first gear and the second gear respectively.

[0047] Description of Reference Numerals

[0048] E motor; D differential;

[0049] C1 first clutch; C2 second clutch;

[0050] G1 is the first gear; G2 is the second gear; G3 is the third gear; G4 is the fourth gear; G5 is the fifth gear; G6 is the sixth gear; G7 is the seventh gear;

[0051] Se motor shaft; Si input shaft; S1 first shaft; S2 second shaft; Sd output half shaft;

[0052] A is axial; R is radial. DETAILED DESCRIPTION

[0053] The exemplary embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present invention, and are not intended to exhaust all possible modes of the present invention, nor to limit the scope of the present invention.

[0054] Unless otherwise specified, refer to Figure 5 , A represents the axial direction of the electric bridge drive system, and the axial direction A is consistent with the axial direction of the motor E in the electric bridge drive system; R represents the radial direction of the electric bridge drive system, and the radial direction R is consistent with the radial direction of the motor E in the electric bridge drive system.

[0055] Reference Figure 5 and Figure 6 The structure of an electric bridge driving system according to one embodiment of the present invention is introduced.

[0056] The electric bridge drive system according to the present invention includes a motor E, a motor shaft Se, a first shaft S1, a second shaft S2, a first clutch C1, a second clutch C2, seven gears (G1 to G7), and a differential D.

[0057] The rotor of the motor E is connected to the motor shaft Se in a rotationally fixed manner (cannot rotate relative to each other), and the motor shaft Se is also connected to the first gear G1 in a rotationally fixed manner to transmit the torque of the motor E to the transmission.

[0058] The first axis S1 and the second axis S2 are arranged parallel to the motor axis Se and offset relative to the motor axis Se in the radial direction R. Preferably, the first axis S1 is located on one radial side of the motor axis Se, and the second axis S2 is located on the other radial side of the motor axis Se. It should be understood that the one side and the other side do not need to be opposite to each other. For example, Figure 6 , the lines connecting the axes of the motor axis Se, the first axis S1 and the second axis S2 can form a triangle.

[0059] The first shaft S1 is mounted with a first clutch C1 , a second gear G2 , and a fourth gear G4 .

[0060] The active part of the first clutch C1 is connected to the second gear G2 in a torsion-proof manner, or the second gear G2 is part of the active part of the first clutch C1, and the active part of the first clutch C1 is sleeved on the outer periphery of the first shaft S1. The driven part of the first clutch C1 is connected to the first shaft S1 in a torsion-proof manner. Optionally, the active part of the first clutch C1 is partially sleeved on the outer periphery of the driven part of the first clutch C1. Preferably, the diameter of the second gear G2 is greater than the diameter of the first clutch C1 (when the second gear G2 is part of the active part of the first clutch C1, the diameter of the first clutch C1 is understood to be the diameter of the other part of the first clutch C1 excluding the second gear G2). When the first clutch C1 is engaged, the first shaft S1 and the second gear G2 are connected in a torsion-proof manner; when the first clutch C1 is disengaged, the second gear G2 and the first shaft S1 can rotate relative to each other. The fourth gear G4 is connected to the first shaft S1 in a torsion-proof manner.

[0061] The second shaft S2 is mounted with a second clutch C2, a third gear G3, and a fifth gear G5.

[0062] The active part of the second clutch C2 is connected to the third gear G3 in a torsion-proof manner, or the third gear G3 is part of the active part of the second clutch C2, and the active part of the second clutch C2 is sleeved on the outer periphery of the second shaft S2. The driven part of the second clutch C2 is connected to the second shaft S2 in a torsion-proof manner, and optionally, the active part of the second clutch C2 is partially sleeved on the outer periphery of the driven part of the second clutch C2. Preferably, the diameter of the third gear G3 is greater than the diameter of the second clutch C2 (when the third gear G3 is part of the active part of the second clutch C2, the diameter of the second clutch C2 is understood to be the diameter of the other part of the second clutch C2 excluding the third gear G3). When the second clutch C2 is engaged, the second shaft S2 and the third gear G3 are connected in a torsion-proof manner; when the second clutch C2 is disengaged, the third gear G3 and the second shaft S2 can rotate relative to each other. The fifth gear G5 and the sixth gear G6 are connected to the second shaft S2 in a torsion-proof manner.

[0063] The output half shaft Sd of the differential gear D is arranged parallel to the motor shaft Se and offset relative to the motor shaft Se. The seventh gear G7 is connected to the housing of the differential gear D in a rotationally fixed manner, or the seventh gear G7 is a part of the housing of the differential gear D.

[0064] The first gear G1 meshes with the second gear G2, the second gear G2 meshes with the third gear G3, the fourth gear G4 meshes with the fifth gear G5, and the sixth gear G6 meshes with the seventh gear G7. Preferably, in order to achieve deceleration of the system, the number of teeth of the second gear G2 is greater than the number of teeth of the first gear G1, the number of teeth of the third gear G3 is greater than the number of teeth of the first gear G1, the number of teeth of the fifth gear G5 is greater than the number of teeth of the fourth gear G4, and the number of teeth of the seventh gear G7 is greater than the number of teeth of the sixth gear G6. Preferably, the above seven gears are all spur gears (straight spur gears or helical spur gears, and preferably helical spur gears).

[0065] Next, refer to Figure 7 and Figure 8 The operation modes of the electric bridge drive system in two speed gears are introduced.

[0066] Reference Figure 7 , when the first clutch C1 is engaged and the second clutch C2 is disengaged, the electric bridge drive system is in the first gear. At this time, the power transmission path is: motor shaft Se, first gear G1, second gear G2, first clutch C1, first shaft S1, fourth gear G4, fifth gear G5, second shaft S2, sixth gear G6, seventh gear G7 to differential D. The number of teeth of the seven gears G1 to G7 are defined as Z1, Z2, Z3, Z4, Z5, Z6 and Z7 respectively. In the first gear, the transmission ratio of the transmission is Z7 / Z6×Z5 / Z4×Z2 / Z1.

[0067] Reference Figure 8 When the first clutch C1 is disengaged and the second clutch C2 is engaged, the electric bridge drive system is in the second gear. At this time, the power transmission path is: motor shaft Se, first gear G1, second gear G2, third gear G3, second clutch C2, second shaft S2, sixth gear G6, seventh gear G7 to differential D. In the second gear, the transmission ratio of the transmission is Z7 / Z6×Z3 / Z2×Z2 / Z1=Z7 / Z6×Z3 / Z1.

[0068] It can be seen that in both speed gears, the electric bridge drive system according to the present invention uses a three-stage gear pair (also referred to as a three-stage gear) for speed change; in the second gear, the second gear G2 plays the role of an idler gear to change the transmission direction, so in the process of switching between the two gears of the system, there is no need to change the rotation direction of the motor; and in the first gear, the three-stage gear reduction can provide a larger transmission ratio.

[0069] The present invention has at least one of the following advantages:

[0070] (i) The electric bridge drive system according to the present invention uses a three-stage gear transmission, and in particular, a larger transmission ratio can be obtained in the first gear, so that the seventh gear G7 with a smaller diameter can be used, so that the system is radially, especially in the direction X (reference Figure 6 ) can have a smaller size, that is, a smaller size of the outer envelope boundary including the motor and the reduction gear. In addition, when the transmission ratio is sufficient, the torque of the motor E can be reduced accordingly, and a smaller motor E can be used, which reduces the cost of the system and also reduces the weight of the system.

[0071] (ii) Both speed gears have three-stage gear pairs for transmission. During the gear switching process, there is no need to change the direction of the motor E, which is simple to control and low in cost.

[0072] (iii) The seventh gear G7 connected to the differential D is meshed with only one gear (i.e., the sixth gear G6). Compared with a solution in which the seventh gear G7 is meshed with two gears, the seventh gear G7 in this embodiment is less likely to wear and has less impact on the NVH of the system.

[0073] (iv) The electric axle drive system uses a clutch to achieve gear switching, and the system can have no power interruption during the gear switching process.

[0074] Of course, the present invention is not limited to the above-mentioned embodiments, and those skilled in the art may make various modifications to the above-mentioned embodiments of the present invention under the guidance of the present invention without departing from the scope of the present invention.

Claims

1. An electric bridge drive system, comprising a motor (E), a motor shaft (Se), a first shaft (S1), a second shaft (S2), a first clutch (C1), a second clutch (C2), a plurality of gears and a differential (D), wherein the motor shaft (Se) is non-rotatably connected to a rotor of the motor (E), wherein: A first gear (G1) is arranged on the motor shaft (Se), a second gear (G2), a fourth gear (G4) and the first clutch (C1) are arranged on the first shaft (S1), a third gear (G3), a fifth gear (G5), a sixth gear (G6) and the second clutch (C2) are arranged on the second shaft (S2), and a seventh gear (G7) is connected to a housing of the differential (D) in a non-rotatable manner. The first gear (G1) is meshed with the second gear (G2), the second gear (G2) is meshed with the third gear (G3), the fourth gear (G4) is meshed with the fifth gear (G5), the sixth gear (G6) is meshed with the seventh gear (G7), When the first clutch (C1) is engaged, the second gear (G2) is connected to the first shaft (S1) in a non-rotatable manner, and when the first clutch (C1) is disengaged, the second gear (G2) and the first shaft (S1) are able to rotate relative to each other. When the second clutch (C2) is engaged, the third gear (G3) and the second shaft (S2) are connected in a non-rotatable manner, and when the second clutch (C2) is disengaged, the third gear (G3) and the second shaft (S2) are rotatable relative to each other.

2. The electric bridge drive system according to claim 1, characterized in that: The active part of the first clutch (C1) is sleeved on the outer periphery of the first shaft (S1), the driven part of the first clutch (C1) is connected to the first shaft (S1) in a non-rotatable manner, and the second gear (G2) is connected to the active part of the first clutch (C1) in a non-rotatable manner. The active part of the second clutch (C2) is sleeved on the outer periphery of the second shaft (S2), the driven part of the second clutch (C2) is connected to the second shaft (S2) in a non-rotatable manner, and the third gear (G3) is connected to the active part of the second clutch (C2) in a non-rotatable manner.

3. The electric bridge drive system according to claim 2, characterized in that: The active part of the first clutch (C1) is partially sleeved on the outer periphery of the driven part of the first clutch (C1), and the active part of the second clutch (C2) is partially sleeved on the outer periphery of the driven part of the second clutch (C2).

4. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: The diameter of the second gear (G2) is larger than the diameter of the first clutch (C1), and the diameter of the third gear (G3) is larger than the diameter of the second clutch (C2).

5. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: The second gear (G2) is part of the active part of the first clutch (C1), and the third gear (G3) is part of the active part of the second clutch (C2).

6. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: In the radial direction of the motor (E), the first shaft (S1) is offsetly arranged on one side of the motor shaft (Se) relative to the motor shaft (Se), and the second shaft (S2) is offsetly arranged on the other side of the motor shaft (Se) relative to the motor shaft (Se).

7. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: The motor shaft (Se), the first shaft (S1), the second shaft (S2), and an output half shaft (Sd) of the differential (D) are arranged in parallel with each other.

8. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: The number of teeth of the second gear (G2) is greater than the number of teeth of the first gear (G1), the number of teeth of the third gear (G3) is greater than the number of teeth of the first gear (G1), the number of teeth of the fifth gear (G5) is greater than the number of teeth of the fourth gear (G4), and the number of teeth of the seventh gear (G7) is greater than the number of teeth of the sixth gear (G6).

9. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: The seven gears are all spur gears.

10. The electric bridge drive system according to any one of claims 1 to 3, characterized in that: When the electric bridge drive system is in a first gear, the first clutch (C1) is engaged and the second clutch (C2) is disengaged; when the electric bridge drive system is in a second gear, the first clutch (C1) is disengaged and the second clutch (C2) is engaged.

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