A hub motor drive axle with a built-in speed reduction mechanism

Abstract

The present invention discloses a hub motor drive axle with a built-in speed reduction mechanism, which includes an axle body and a hub motor. The hub motor includes a motor part, which has a motor part output shaft, a motor part housing, a stator and a rotor. The rotor is fixedly connected to the motor output shaft through a rotor support. A planetary gear speed reduction mechanism is arranged in the rotor cavity. The planetary gear speed reduction mechanism has an output shaft that reduces the rotation of the motor output shaft and outputs it, and a reduction part housing that forms an outer contour. The output shaft of the planetary gear speed reduction mechanism and the motor output shaft share a common shaft. By integrating the reducer in the rotor cavity and sharing a common shaft with the motor, the present invention realizes the miniaturization of the hub motor, ultimately effectively reduces the weight of the axle body and the unsprung mass, improves the comfort of the whole vehicle, reduces the cost of the whole vehicle, improves the transmission efficiency, and at the same time solves the problem of the difficulty in industrializing the original hub drive.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and more specifically, to a wheel hub motor drive axle. Background Art

[0002] Due to the non-renewable nature of petroleum energy, new energy pure electric vehicles have gradually become an industry that countries compete to encourage the development of. Encouraged by government policies, the pure electric vehicle industry has developed vigorously. However, at present, most of the electric drive axles of domestic and international pure electric vehicles are mainly wheel-side drive and direct central motor drive. The truly wheel hub motor electric drive axle is extremely rare. Even for the few wheel hub motor electric drive axles, due to their design concepts and structural limitations, it is very difficult to truly achieve the lightweight of the overall structure.

[0003] For the above reasons, it is necessary to improve the drive axle of the existing technology. Summary of the Invention

[0004] In view of the deficiencies in the prior art, the present invention provides a wheel hub motor drive axle with an internal reduction mechanism.

[0005] The present application is implemented by the following technical solutions: A wheel hub motor drive axle with an internal reduction mechanism includes a bridge body. Wheel hub motors are provided on both sides of the bridge body. The wheel hub motor includes a motor part, which has a motor part output shaft and a motor part housing forming an outer contour. A stator is fixedly provided on the inner wall of the motor part housing. A rotor is provided inside the stator. The rotor is fixedly connected to the motor output shaft through a rotor support member for transmitting rotational motion to the motor output shaft. A wheel hub is fixedly connected to the motor output shaft. A disc brake mechanism is provided on the bridge body. The disc brake mechanism includes a brake disc fixedly connected to the output shaft of the wheel hub motor. A planetary gear reduction mechanism is provided inside the rotor cavity. The planetary gear reduction mechanism has an output shaft that decelerates the rotation of the motor output shaft and outputs it, and a reduction part housing forming an outer contour. The output shaft of the planetary gear reduction mechanism and the motor output shaft share the same shaft.

[0006] In the above technical solution, a left brake pad and a right brake pad are respectively arranged on both sides of the brake disc. A cylinder is arranged on one side of the right brake pad. A biasing member is connected to the cylinder rod of the cylinder. A push rod member is arranged opposite to the biasing member. The push rod member is used to push the right brake pad. It further includes a main caliper body which is fixedly arranged on a bracket. The above-mentioned bracket is fixedly connected to the bridge body. A cavity for accommodating the biasing member and the push rod member is formed on the main caliper body. A sub-caliper body is arranged on one side of the left brake pad. The sub-caliper body is fixedly connected to the left brake pad. The sub-caliper body is fixedly connected to the main caliper body. When the cylinder pushes the biasing member to rotate, so that the biasing member biases the push rod member to one side, the biasing member simultaneously biases the main caliper body to the other side.

[0007] In the above technical solution, the planetary gear reduction mechanism includes a sun gear arranged in the reduction part housing and a central gear meshing with the sun gear. The output shaft of the planetary gear reduction mechanism is arranged on the central gear.

[0008] In the above technical solution, the biasing member includes two biasing terminals in the shape of cams and a connecting portion connected to the cylinder rod. The push rod member includes a push rod and a push plate connected to the end of the push rod.

[0009] In the above technical solution, a sliding pin is arranged on the bracket. The sub-caliper body is in sliding fit with the sliding pin.

[0010] In the above technical solution, the left brake pad and the right brake pad are powder metallurgy brake pads.

[0011] In the above technical solution, the brake disc is an alloy steel brake disc.

[0012] The present invention has the following beneficial effects: By integrating the reducer into the inner cavity of the rotor and sharing a shaft with the motor, the present invention realizes the miniaturization of the in-wheel motor, finally effectively reduces the weight of the bridge body and the unsprung mass, improves the comfort of the whole vehicle, reduces the cost of the whole vehicle, improves the transmission efficiency, and at the same time solves the problem of difficult industrialization of the original in-wheel drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a three-dimensional structural schematic diagram of the present invention.

[0014] Figure 2 It is a structural schematic diagram of the in-wheel motor of the present invention.

[0015] Figure 3 It is a structural schematic diagram of the disc brake mechanism.

[0016] Figure 4 It is a three-dimensional structural schematic diagram of the main caliper body.

[0017] Figure 5 Schematic diagram of the cooperation between the bridge body and the in-wheel motor.

[0018] Figure 6 Schematic three-dimensional structure diagram of the biasing member.

[0019] Figure 7 Schematic diagram of the cooperation between the push rod member and the biasing member.

[0020] Figure 8 Schematic structure diagram of the reducer housing. Specific embodiments

[0021] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments: Refer to Figures 1 to 8 , an in-wheel motor drive bridge with a built-in speed reduction mechanism, comprising a bridge body 2, and in-wheel motors 1 are arranged on both sides of the bridge body 2. The in-wheel motor 1 includes a motor part 10, which has a motor part output shaft 100 and a motor part housing 11 forming an outer contour. A stator 12 is fixedly arranged on the inner wall of the motor part housing 11. A rotor 13 is arranged inside the stator 12. The rotor 13 is fixedly connected to the motor output shaft 100 through a rotor support member 14 for transmitting rotational motion to the motor output shaft 100.

[0022] A planetary gear speed reduction mechanism 3 is arranged inside the cavity of the rotor 13. The planetary gear speed reduction mechanism 3 has an output shaft for reducing the rotation of the motor output shaft 100 and a reduction part housing 30 forming an outer contour. The output shaft of the planetary gear speed reduction mechanism and the motor output shaft 100 share the same shaft. As a specific example of the planetary gear speed reduction mechanism, the planetary gear speed reduction mechanism of the present application includes a sun gear 31 arranged inside the reduction part housing 30 and a central gear 32 meshing with the sun gear. The output shaft of the planetary gear speed reduction mechanism is arranged on the central gear 32. A wheel hub 4 is fixedly connected to the motor output shaft 100.

[0023] In the above structure, by integrating the planetary gear speed reduction mechanism 3 into the rotor cavity, the rotor space is reasonably designed and utilized, so that the volume of the entire in-wheel motor can be reduced.

[0024] Inside the motor part housing 11, a water-cooling channel 110 distributed in an S shape is provided. At the inlet of the water-cooling channel 100, a water inlet joint (not shown in the drawings) is arranged, and at the outlet of the water-cooling channel, a water outlet joint (not shown in the drawings) is arranged. By introducing cooling water into the water inlet joint and circulating it along the water-cooling channel 110 to be discharged at the water outlet joint, the heat generated by the stator can be effectively cooled, and heat exchange can be carried out with the internal space to achieve a heat dissipation effect. Further, small circular ribs (not shown in the drawings) are provided outside the motor housing. Through the above small circular ribs, the heat exchange area between the motor part housing 11 and the outside is increased, thereby further enhancing the heat dissipation effect.

[0025] An oil channel through which cooling oil passes is formed between the stator 12 and the rotor 13. An oil inlet joint communicating with the inlet of the oil channel and an oil outlet joint communicating with the outlet of the oil channel are arranged on the motor part housing 11. The cooling oil enters from the oil inlet under the action of the external oil pump pressure, flows out from the oil outlet after passing through the oil channel. Through the above cooling oil, the heat generated by the operation of the rotor core, permanent magnet and bearing is cooled, and heat exchange is carried out with the reducer housing.

[0026] In the above structure, through the design of the water-oil exchange cooling and surface self-cooling system, when the hub motor is under rated load, the stator winding temperature is controlled at about 100°, the peak operation is 135°, the rotor permanent magnet is 120°, and the bearing temperature is 70°. The operating temperature is relatively reasonable, and the service life of the whole machine is extended. The overall structure of the machine is relatively compact, with a shorter length and lighter weight. It is about 150 KG lighter than the outer rotor single-tire hub motor, reducing the weight of the whole vehicle and increasing the electromagnetic endurance mileage.

[0027] Further preferably, a water cavity 30a is formed inside the reduction part housing 30. A water inlet joint (not shown in the drawings) and a water outlet joint (not shown in the drawings) communicating with the water cavity 30a are arranged on the end face of the reducer housing 30. By introducing cooling water into the water inlet joint and circulating it along the water cavity 30a to be discharged at the water outlet joint, the heat generated by each component of the planetary gear reduction mechanism during operation inside the reducer housing 30 can be effectively reduced. In this application, the supply parts for supplying the cooling water source to the reducer housing 30 and the motor part housing 11 both adopt the water tank on the vehicle, and the above structure is not described in detail in the embodiment.

[0028] A disc brake mechanism 4 is provided on the bridge body 2. The disc brake mechanism 4 includes a brake disc 40 fixedly connected to the output shaft 100 of the hub motor. A left brake pad 40a and a right brake pad 40b are respectively arranged on both sides of the brake disc 40. A cylinder 41 is arranged on one side of the right brake pad 40b. A biasing member 5 is connected to the cylinder rod of the cylinder 41. A push rod member 6 is arranged opposite to the biasing member 5, and the push rod member 6 is used to push the right brake pad 40b. It further includes a main caliper body 7. The main caliper body 7 is fixedly arranged on a bracket 200, and the above-mentioned bracket 200 is fixedly connected to the bridge body 2. A cavity for accommodating the biasing member 5 and the push rod member 6 is formed on the main caliper body 7. A secondary caliper body 8 is arranged on one side of the left brake pad 40a. The secondary caliper body 8 is fixedly connected to the left brake pad 40a, and the secondary caliper body 8 is fixedly connected to the main caliper body 7. When the cylinder pushes the biasing member 5 to rotate, so that the biasing member 5 biases the push rod member to one side, the biasing member biases the main caliper body to the other side at the same time. Specifically, the biasing member 5 includes two biasing terminals 50 in the shape of cams and a connecting portion 51 connected to the cylinder rod. The push rod member 6 includes a push rod 60 and a push plate 61 connected to the end of the push rod.

[0029] Preferably, the left brake pad and the right brake pad are powder metallurgy brake pads, and the brake disc is an alloy steel brake disc. After the left brake pad and the right brake pad adopt the above materials, they have the following advantages: a. High wear resistance. Ensure the life of the brake pads for a sufficient mileage; b. High heat resistance. It can maintain the mechanical properties and mechanical properties basically unchanged when instantaneously heated to 900°C and at 400°C for a long time; c. High friction coefficient stability. When the vehicle brakes under high temperature, high speed and high pressure conditions, the friction coefficient of the brake pads can be sufficiently stable; d. High anti-bonding property. The anti-bonding property of the friction material greatly affects the stability of the friction coefficient. The surface of the friction pair should not be bonded, otherwise it will cause the friction material to flake and weld during work, and it should be stable and vibration-free during work. When the brake disc adopts alloy steel material, it has the physical property of high temperature resistance, will not generate hot spots and fatigue cracks at 1000°C, the braking force will not decline, and the wear resistance of the brake disc is greatly increased. A sliding pin 300 is arranged on the bracket 200, and the secondary caliper body is slidably matched with the sliding pin 300.

[0030] The principle of the present invention is as follows: When the input pressure F1 is applied to the cylinder, the cylinder rod of the cylinder pushes the biasing member to rotate and extend to the left, thereby eliminating the gap between the right brake pad 40b and the right side surface of the brake disc 40, and starting to output the pressure F2 to be transmitted to the right brake pad 40b. At this time, the right brake pad 40b presses the pressure F2 against the rotating brake disc 40. Since the axial movement of the brake disc 40 is restricted, the brake disc 40 transmits the reaction force of F2 back to the main caliper body 7 through the push rod member and the biasing member; at the same time, the main caliper body 7 also transmits the reaction force of F2 to the sub-caliper body, so that the sub-caliper body receives a tensile force to the right and starts to float; since the sliding pin 300 is fixed on the bracket 10 and only supports and prevents rotation of the main caliper body 7 and the sub-caliper body 8 without restricting left and right floating; as the biasing member rotates continuously, both the sub-caliper body 8 and the main caliper body 7 float to the right at the same time until the gap between the left powder metallurgy brake pad 2 and the left side surface of the brake disc 40 is eliminated. At this time, the sub-caliper body 8 generates a pressure F3 on the left powder metallurgy brake pad 2, so that the left powder metallurgy brake pad 2 and the right brake pad 40b press on both side surfaces of the brake disc 40 with a braking force of F2 = F3, and generate a braking torque T, and finally brake the rotating brake disc 40.

[0031] Detection units for detecting their rotational speeds n1 and n2 are respectively provided on the in-wheel motors 1 provided on both sides of the bridge body 2, and a control unit is further included for processing the data measured by the detection units and controlling the rotational speed and torque of the in-wheel motor 1 according to the above data. Wherein: The control unit determines that the whole vehicle enters the differential mode when the following three criteria are simultaneously met according to the physical quantities measured by the detection unit; otherwise, the whole vehicle executes the standard torque control mode.

[0032] The three criteria are as follows: Criterion 1: where k1 is a calibratable constant, that is, only when the rotational speed difference between the two in-wheel motors reaches a certain level, the vehicle enters the differential mode, and the magnitude of the above certain level is determined by calibrating the constant k1;

[0033] Criterion 2: |M ref | > |M1|, where M ref is the reference torque of the torque mode motor, calibrated according to the magnitude of the vehicle throttle signal, and M1 is a calibratable constant. By calibrating the constant M1, it is determined that when the throttle reaches the corresponding value, the vehicle enters the differential mode;

[0034] Criterion 3: |n1| < |n k |, n k is a calibratable speed constant, and by calibrating the constant n k it is determined that when the speed is greater than the corresponding value, the vehicle will not enter the differential mode;

[0035] When the control unit measures that three criteria are met, the differential mode is activated. In this mode, the N1, N2 speed mode references and M are obtained in the following ways: 1_PI (Torque output of speed 1 controller) and M 2_PI (Torque output of speed 2 controller):

[0036] First, obtain the initial existing speed n; according to the obtained initial existing speed, obtain the N1, N2 speed mode references according to the following formula:

[0037] |N1| = |n·(1 - k2)|; |N2| = |n|·(1 + k2),

[0038] where K2 is calculated according to the following formula: In this formula, k3 is a calibratable constant, n max is the maximum motor speed, and M max is the maximum motor torque;

[0039] Send the obtained two speeds N1 and N2 to the corresponding in-wheel motors respectively. The in-wheel motors execute the speed modes N1 and N2, and the differential mode is executed. The vehicle can turn differentially, and a speed closed-loop controller will be applied (the speed closed-loop controller uses a proportional-integral PI regulator to control). M 1_PI is the torque output of one of the in-wheel motor speed closed-loop controllers, and M 2_PI is the torque output of the other in-wheel motor speed closed-loop controller. The torque output should meet the following conditions: 0 < |M 1_PI | + |M 2_PI | < 2·|M ref |, 0 < |M 1_PI | < k3·|M ref |, 0 < |M 2_PI | < k3·|M ref |;

[0040] Among them, when the differential mode is activated, its initial existing speed n is calculated according to the following formula: That is, the average value of the previous K speeds before the initial existing speed sampling.

[0041] When the control unit measures that the three criteria are not met, the standard torque mode is activated. When the standard torque control mode is executed, the torques of the two in-wheel motors are the same.

[0042] The above structure determines whether to enter the differential mode by judging the rotational speed difference between the two in-wheel motors, the vehicle throttle signal, and the speed value. And in the differential mode, the rotational speeds and torques of the two in-wheel motors are controlled. No additional auxiliary sensors are required, and the differential is fully implemented by software without additional maintenance costs; the system is safer and more stable, thus making it possible for in-wheel motors to be widely used in new energy.

[0043] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification in this application are only the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements. The above-mentioned changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A wheel hub motor drive axle with a built-in speed reduction mechanism, comprising a bridge body, wheel hub motors are arranged on both sides of the bridge body, the wheel hub motor includes a motor part, which has a motor part output shaft and a motor part housing forming an outer contour, a stator is fixedly arranged on the inner wall of the motor part housing, a rotor is arranged in the stator, the rotor is fixedly connected to the motor output shaft through a rotor support member for transmitting rotational motion to the motor output shaft, a wheel hub is fixedly connected to the motor output shaft, a disc brake mechanism is arranged on the bridge body, the disc brake mechanism includes a brake disc fixedly connected to the output shaft of the wheel hub motor, characterized in that: A planetary gear reduction mechanism is disposed within the rotor inner cavity. The planetary gear reduction mechanism has an output shaft that reduces the rotation of the motor output shaft and outputs it, and a reduction part housing that forms an outer contour. The output shaft of the planetary gear reduction mechanism and the motor output shaft share a common shaft. A left brake pad and a right brake pad are respectively disposed on both sides of the brake disc. A cylinder is disposed on one side of the right brake pad. A biasing member is connected to the cylinder rod of the cylinder. A push rod member is disposed opposite to the biasing member. The push rod member is used to push the right brake pad. It further includes a main caliper body that is fixedly disposed on a bracket. The above-mentioned bracket and the bridge body are fixedly connected. A cavity for accommodating the biasing member and the push rod member is formed on the main caliper body. A secondary caliper body is disposed on one side of the left brake pad. The secondary caliper body and the left brake pad are fixedly connected. The secondary caliper body and the main caliper body are fixedly connected. When the cylinder pushes the biasing member to rotate, causing the biasing member to bias the push rod member to one side, the biasing member simultaneously biases the main caliper body to the other side. The biasing member includes two biasing terminals in the shape of cams and a connecting portion connected to the cylinder rod. The push rod member includes a push rod and a push plate connected to the end of the push rod. Detection units for detecting their rotational speeds n1 and n2 are respectively disposed on the in-wheel motors disposed on both sides of the bridge body. It further includes a control unit for processing the data measured by the detection units and controlling the rotational speed and torque of the in-wheel motors according to the above data. Among them: The control unit determines that the whole vehicle enters the differential mode when the following three criteria are simultaneously met according to the physical quantities measured by the detection units; otherwise, the whole vehicle executes the standard torque control mode: Standard 1: Where k1 is a calibratable constant, that is, only when the rotational speed difference between the two hub motors reaches a certain level does it enter the differential mode, and the magnitude of the above-mentioned certain level is determined by calibrating the constant k1; Standard 2: |M ref | > |M1|, where M ref is the reference torque of the torque mode motor, calibrated according to the magnitude of the vehicle throttle signal, and M1 is a calibratable constant. By means of the calibratable constant M1, it is determined that when the throttle reaches the corresponding value, the differential mode is entered; Standard 3: |n1| < |n k |, where n k is a calibratable speed constant. By calibrating the constant n k it is determined that when the speed is greater than the corresponding value, the differential mode will not be entered; When the control unit measures that three criteria are met, the differential mode is activated, in which the N1, N2 speed mode references and M are obtained in the following manner 1_PI and M 2_PI : First, obtain the initial existing speed n; according to the obtained initial existing speed, obtain the N1 and N2 speed mode references according to the following formula: |N1| = |n|·(1 - k2); |N2| = |n|·(1 + k2), where K2 is calculated according to the following formula: In this formula, k3 is a calibratable constant, n max is the maximum speed of the motor, M max is the maximum torque of the motor; The obtained two speeds N1 and N2 are respectively sent to the corresponding in-wheel motors. The in-wheel motors execute speed modes N1 and N2, and the differential mode is executed. The whole vehicle can turn differentially, M 1_PI is the torque output of one of the in-wheel motor speed closed-loop controllers, M 2_PI is the torque output of the other in-wheel motor speed closed-loop controller. The torque output should meet the following conditions: 0 < |M 1_PI | + |M 2_PI | < 2·|M ref |, 0 < |M 1_PI | < k3·|M ref |, 0 < |M 2_PI | < k3·|M ref |; Wherein, when the differential mode is activated, its initial existing speed n is the average value of the previous K speeds before the initial existing speed sampling. When the control unit measures that the three criteria are not met, the standard torque mode is activated. When the standard torque control mode is executed, the torques of the two in-wheel motors are the same.

2. The hub motor drive axle with a built-in speed reduction mechanism according to claim 1, characterized in that: The planetary gear reduction mechanism includes a sun gear disposed within the reduction part housing and a central gear meshing with the sun gear. The output shaft of the planetary gear reduction mechanism is disposed on the central gear.

3. The hub motor drive axle with a built-in speed reduction mechanism as described in claim 1, characterized in that: A sliding pin is disposed on the bracket. The secondary caliper body and the sliding pin are in sliding fit.

4. The hub motor drive axle with a built-in speed reduction mechanism as described in claim 1, wherein: The left brake pad and the right brake pad are powder metallurgy brake pads.

5. The hub motor drive axle with a built-in speed reduction mechanism according to claim 1, characterized in that: The brake disc is an alloy steel brake disc.

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