Electric driving system of tracked vehicle

Abstract

The invention discloses an electric driving system of a tracked vehicle, which comprises a shell, a motor and a coaxial speed reducer, and the motor and the coaxial speed reducer are integrated in the shell; the motor comprises a motor shaft which is a motor torque output end and is connected with an input shaft of the speed reducer; the coaxial speed reducer is a planet row speed reducing mechanism, the planet row speed reducing mechanism comprises an input shaft and an output shaft, and the output shaft is connected with the track driving wheel; the planet row speed reduction mechanism of the coaxial speed reducer can be of a planet wheel structure of double gears which are coaxially and fixedly connected, a large-reduction-ratio coaxial speed reduction structure is formed, and the whole system is higher in integration degree, larger in power density and smaller in size.

Description

Technical Field

[0001] The present invention discloses an electric drive system for a tracked vehicle, which belongs to the technical field of tracked vehicle drive according to the International Patent Classification (IPC). Background Art

[0002] With the development of electric drive technology, more and more tracked vehicles adopt electric drive, such as: pure electric drive tracked vehicles, fuel cell drive tracked vehicles, range-extended electric drive tracked vehicles, series hybrid tracked vehicles, and so on. The tracked electric drive system includes a drive motor, a reduction mechanism, a lubrication and cooling system, a housing, etc.; the housing of the tracked electric drive system is installed on the vehicle body, and its output shaft directly drives the tracked drive wheel, no longer requiring a drive axle, simplifying the overall vehicle structure, increasing the space available for the chassis, and realizing complex vehicle dynamics control. The drive motor is the power source and outputs torque. Usually, the drive wheel of a vehicle requires a relatively large torque, with a rotational speed of several hundred to one or two thousand revolutions per minute; on the other hand, the torque of the motor is usually not easily too large, and the rotational speed can reach several thousand to twenty thousand revolutions per minute. The solution to this problem is to add a set of speed reduction and torque increase mechanisms, which can reduce the motor speed and increase the torque by several times or dozens of times.

[0003] Many electric drive systems use a reduction ratio of about 10 for the reducer, which requires a relatively large motor torque, and the cost, volume, and weight are relatively large.

[0004] For example, the maximum speed of a tracked vehicle is 40 km / h, the radius of the tracked drive wheel is 180 mm, and the torque requirement of the tracked drive wheel is 1000 N·m. If the speed ratio of the motor reducer is 10:1, the motor torque is 100 N·m and the motor speed is 6000 rpm; if the reducer speed ratio is 20:1, the motor torque drops to 50 N·m and the motor speed is 12000 rpm; if the reducer speed ratio is 30:1, the motor torque is 33.3 N·m and the motor speed is 18000 rpm.

[0005] It can be seen that increasing the reduction ratio can reduce the motor torque requirement, thereby reducing the motor weight and volume, which is very important for the motor drive system. Usually, the internal space of a tracked vehicle is very small, so reducing the motor volume is very important.

[0006] Equally important is to reduce the volume of the tracked drive system and the occupied space, which is also a topic that needs to be studied by those skilled in the art.

[0007] Chinese patent document CN219883830U discloses a track electric drive system, which includes a motor and a reducer. The motor and the reducer are separated, and the input shaft and the output shaft of the reducer are perpendicular to each other. The motor of this system outputs power through the motor shaft, enters the reducer through the input shaft of the reducer, undergoes speed reduction and torque increase, and is output from the output shaft to drive the track drive wheel. The motor and the reducer of this system are separated, with a low integration level, large occupied space, and squeezing the space required for the payload.

[0008] Patent document CN 207218453 discloses a design of an electric drive system, which integrates the motor, the reducer, and the differential into one body to improve the system integration level. The reducer is a two-stage parallel shaft gear reducer, and the maximum speed ratio can reach about 25. The motor shaft outputs power to the input shaft of the reducer, undergoes two-stage speed reduction and torque increase by the reducer, and is output through the differential. Some track electric drive systems are similar to this system, with two-stage parallel shaft gear reduction, but do not require a differential. For such an integrated motor and reducer system, the problem of occupied space has been improved. The reducer adopts a parallel shaft gear mechanism, and the driving gear shaft and the driven gear shaft are parallel to each other; usually, the system requires a large speed ratio, so the diameter of the driven gear is large, increasing the lateral dimension, and presenting an L shape when viewed from the side. Therefore, there is still room for improvement in the space utilization rate of this shape of the drive system.

[0009] Vehicles are all equipped with braking devices (brake devices). The brakes of track vehicles are usually arranged on the output drive shaft of the track drive system. The brake disc is installed on the drive shaft of the electric drive system, and the brake caliper is installed on the vehicle chassis; or, the brake drum is installed on the drive wheel, and the brake friction plate is installed on the vehicle chassis. No matter which type of brake, it needs to occupy axial space and increase the axial length. Summary of the Invention

[0010] Aiming at the deficiencies of the prior art, the present invention provides a track vehicle electric drive system. Through the integrated design of the motor and the reduction mechanism, and the reduction mechanism adopts a structure with the input shaft and the output shaft coaxial, the volume of the system is reduced and the space utilization rate inside the vehicle is high.

[0011] To achieve the above object, the present invention is realized through the following technical solutions:

[0012] A track vehicle electric drive system includes a housing, a motor, and a coaxial reducer. The motor and the coaxial reducer are integrated in the housing.

[0013] The motor includes a motor shaft, which is the torque output end of the motor and is connected to the input shaft of the coaxial reducer.

[0014] The coaxial reducer is a planetary gear reduction mechanism. The planetary gear reduction mechanism includes an input shaft and an output shaft, and the output shaft is connected to the track drive wheel.

[0015] The motor shaft, the input shaft and the output shaft are coaxial.

[0016] Furthermore, the planetary gear reduction mechanism includes a sun gear, a plurality of planetary gears, a planet carrier, a support ring gear, and an output ring gear. The sun gear is connected to the input shaft, and this input shaft is connected to the motor shaft; the shafts of the planetary gears are installed on the planet carrier, and the planetary gears rotate around their own shafts and simultaneously revolve around the axis of the planet carrier; the planetary gears cooperate with the support ring gear and the output ring gear respectively. The output ring gear is connected to the output shaft for outputting torque. The planetary gear includes a first gear and a second gear fixedly connected coaxially. The first gear meshes with the support ring gear, and the support ring gear is fixed. The second gear meshes with the output ring gear, and the output ring gear is connected to the output shaft to form the output shaft of the reduction mechanism.

[0017] The working process of the electric drive system of the tracked vehicle is as follows: The motor rotor outputs torque, which is transmitted to the sun gear through the motor shaft. The sun gear meshes with the first gear of the planetary gear and acts on the meshing point; The first gear meshes with the support ring gear. Since the rotational speed of the support ring gear is zero, the speed of the meshing point is zero, which is called the instantaneous center of motion; The second gear of the planetary gear is fixedly connected coaxially with the first gear and moves with it; The second gear meshes with the output ring gear, and the meshing point of the output ring gear moves along the tangent direction; The output ring gear is connected to the output shaft and drives the output shaft to rotate;

[0018] Input / output speed ratio of the electric drive system of the tracked vehicle:

[0019]

[0020] Among them, the number of teeth or the effective radius of the sun gear is represented by S,; the number of teeth or the effective radius of the first gear is represented by P1; the number of teeth or the effective radius of the second gear is represented by P2; the rotational speed of the sun gear is represented by n S , and the rotational speed of the output ring gear is represented by n R2 .

[0021] The present invention discloses an electric drive system for a crawler vehicle, which uses a motor to connect to a planetary gear reducer. The motor shaft, input shaft, and output shaft are coaxial, and the external contour is close to a cylindrical shape with a regular shape, resulting in a high utilization rate of the vehicle interior space. In the present invention, the planetary gear reduction mechanism of the coaxial reducer can be a planetary gear structure with coaxial and fixedly connected double gears, forming a coaxial reduction structure with a large reduction ratio, making the entire system more integrated, having a higher power density, and a smaller volume. In the present invention, the planetary gear reduction mechanism of the reducer can also adopt a two-stage planetary gear reduction mechanism, where the output shaft of the first-stage planetary gear reduction mechanism serves as the input shaft of the second-stage planetary gear reduction mechanism; the two-stage planetary gear reduction mechanisms are connected in series, and the speed ratios are multiplied to obtain the input / output speed ratio of the electric drive system. For both structures of the planetary gear reduction mechanism, a vehicle brake can be further integrated. A wet multi-disc brake is used and integrated with the motor and the coaxial reducer, greatly improving the system integration and reducing the space occupied by the electric drive and the brake. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. is a schematic structural diagram of an embodiment of the present invention.

[0023] Figure 2 FIG. is a schematic cooperation diagram of an embodiment of the present invention.

[0024] Figure 3 FIG. is a schematic diagram of the integrated brake of the present invention.

[0025] Figure 4 FIG. is a schematic structural diagram of another embodiment of the present invention.

[0026] Figure 5 FIG. is a schematic diagram of the integrated brake of another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present invention will be further described below with reference to the accompanying drawings:

[0028] Embodiment: Please refer to Figures 1 to 5, A track vehicle electric drive system, which includes a housing 1, a motor 5 and a coaxial reducer 10. The motor 5 and the coaxial reducer 10 are integrated within the housing 1. The motor includes a stator 2, a rotor 3 and a rotor shaft, i.e., the motor shaft 4, which is the torque output end of the motor and is connected to the input shaft of the coaxial reducer. The coaxial reducer is a planetary gear reduction mechanism, which includes an input shaft and an output shaft 12, and the output shaft 12 is connected to the track driving wheel. The motor shaft 4, the input shaft and the output shaft 12 are coaxial. In the present invention, the planetary gear reduction mechanism of the coaxial reducer can be a planetary gear structure of coaxial fixed-connected double gears, or a two-stage planetary gear reduction mechanism can be adopted to finally form a large reduction ratio reduction structure, making the entire system have higher integration, greater power density and smaller volume. For the planetary gear reduction mechanisms of the two structures, a vehicle brake can be further integrated. A wet multi-disc brake or other brakes can be adopted and integrated with the motor and the coaxial reducer into one body, greatly improving the system integration and reducing the space occupied by the electric drive and the brake.

[0029] To further illustrate the solution of this application, the specific description is as follows

[0030] Embodiment 1:

[0031] Please refer to Figure 1 , The track vehicle motor drive system includes: a housing 1, a motor 5, and a reducer (coaxial reducer 10). The housing 1 is connected to the vehicle body and is non-rotating; all components installed on or fixedly connected to the housing are non-rotating, and are simply referred to as fixed when there is no ambiguity. The motor 5 includes a stator 2 and a rotor 3. The motor stator is fixedly installed on the housing 1 and is non-rotating; the motor rotor shaft, i.e., the motor shaft 4, is supported by bearings and can rotate relative to the motor stator / housing. The reducer 10 includes a sun gear 6, several planetary gears 7, a planet carrier 8, a support ring gear 9, an output ring gear 11, etc.; the sun gear 6 is connected to an intermediate shaft as the input shaft and is connected to the motor rotor shaft; the planetary gear 7 is formed by coaxially fixedly connecting a first gear 7-1 and a second gear 7-2; the shaft of the planetary gear 7 is installed on the planet carrier 8, and the planet carrier 8 is coaxial with the motor rotor and the sun gear; the planetary gear 7 rotates around its own axis and at the same time follows the axis to revolve around the axis of the planet carrier; the output ring gear 11 is connected to the output shaft 12, and the output shaft 12 is connected to the track driving wheel.

[0032] The input shaft of the speed reducer mechanism is directly or indirectly connected to the sun gear 6; there are several pairs of planetary gears, and each pair of planetary gears consists of two gears fixedly connected coaxially. Among them, the one meshing with the sun gear is called the input planetary gear, i.e., the first gear 7-1, and the other is called the output planetary gear, i.e., the second gear 7-2; the shafts of these planetary gears are fixedly installed on the planet carrier 8; there are two ring gears, one is the support ring gear 9, and the other is the output ring gear 11. Connection method: the motor rotor 3 is connected to the sun gear 6; the sun gear 6 meshes with the input planetary gear (the first gear 7-1) in the planetary gear pair; the input planetary gear (the first gear 7-1) meshes with the support ring gear 9 at the same time; the input planetary gear (the first gear 7-1) is fixedly connected to the output planetary gear (the second gear 7-2), driving the output planetary gear (the second gear 7-2) to rotate, and the rotation includes revolution and rotation; the output planetary gear (the second gear 7-2) meshes with the output ring gear 11.

[0033] Working principle of the motor drive system for tracked vehicles: The motor rotor 3 outputs torque, which is transmitted to the sun gear 6 through the rotor shaft, i.e., the motor shaft 4; the sun gear 6 meshes with the first gear 7-1 of the planetary gear and acts on the meshing point; the meshing points on both sides move at the same speed; the first gear 7-1 of the planetary gear meshes with the support ring gear 9. Since the rotational speed of the support ring gear 9 is zero, the speed of the meshing point is zero, which is called the instantaneous center of motion; the second gear 7-2 of the planetary gear is fixedly connected coaxially with the first gear 7-1 and moves with it; the second planetary gear 7-2 meshes with the output ring gear 11, driving the meshing point of the output ring gear 11 to move along the tangent direction, or driving the output ring gear 11 to rotate; the output ring gear 11 is connected to the output shaft 12, driving the output shaft to rotate.

[0034] Please refer to Figure 2 , represent the number of teeth or effective radius of the sun gear 6 with S; represent the number of teeth or effective radius of the first gear 7-1 of the planetary gear with P1; represent the number of teeth or effective radius of the second gear 7-2 of the planetary gear with P2; represent the number of teeth or effective radius of the support ring gear 9 with R1; represent the number of teeth or effective radius of the output ring gear 11 with R2, and there are the following geometric relationships:

[0035] R1 = S + 2P1......(1)

[0036] and

[0037] R2 = S + P1 + P2......(2)

[0038] The sun gear 6 serves as the input shaft and rotates at a constant speed in the clockwise direction, with a rotational speed of n S , the sun gear 6 meshes with the first gear 7-1 of the planetary gear at point A, and the linear velocity at point A is n S ·S: that is, v A = n S ·S.

[0039] The sun gear 6 drives the first gear 7-1 of the planetary gear. The first gear 7-1 makes a planar motion. Point B on the first gear 7-1 meshes with the sun gear 6. The moving speeds of point B and point A are equal: v B =v A =n S ·S.

[0040] Point C on the first gear P1 meshes with point D on the support ring gear R1, and they have the same moving speed. The support ring gear R1 is connected to the housing and is stationary without rotation, and the speed of each point is zero. Therefore, there is: v C =v D =0.

[0041] From the perspective of kinematics, the first gear 7-1 of the planetary gear is making a planar motion. The instantaneous speed of point C is zero, which is the instantaneous center. The second gear 7-2 of the planetary gear is connected to the first gear 7-1 as a whole and makes a planar motion together, rotating around the instantaneous center. The linear speed of the meshing point E between the second gear 7-2 and the output ring gear 11 is determined by the planar motion rule: its linear speed v E The ratio to the line segment CE is equal to the ratio of the linear speed of point B on the first gear 7-1 to the line segment CB: The linear speed of the meshing point F between the output ring gear 11 and the second gear 7-2 is: The rotational speed of the output ring gear 11 is:

[0042] In summary, the input / output rotational speed ratio of the track vehicle motor drive system:

[0043]

[0044] For example, if S = 18, R1 = 66, R2 = 60, P1 = 24, P2 = 18, then R1 = S + 2P1 and R2 = S + P1 + P2. According to the formula, the speed ratio is calculated as: Spd Ratio = 26.67.

[0045] In engineering design, through techniques such as gear modification design, on the basis of the geometric relationships R1 = S + 2P1 and R2 = S + P1 + P2, one tooth can be added or subtracted from the ring gears R1 and R2, that is:

[0046] R1 = S + 2P1 ± 1

[0047] R2 = S + P1 + P2 ± 1

[0048] For example, if S = 21, R1 = 90, R2 = 78, P1 = 34, and P2 = 22, the formula calculates Spd Ratio = 20.78, the actual speed ratio is 20.86, and the error is 0.40%. In this case, the error of formula (3) is very small, less than 1%, and it can still be used.

[0049] In the design of the present invention, the vehicle brake can be integrated into the motor drive system. Specifically, a brake 13 can be installed on the input shaft or the output shaft 12, as shown in Figure 3 , the brake 13 is preferably a wet multi-disc brake, and other forms of brakes can also be used. Or a brake can be installed on the planet carrier 8.

[0050] In the design of the present invention, a reduction mechanism for coaxial transmission with a large reduction ratio is used in the motor drive system of a tracked vehicle.

[0051] The innovation points of an electric drive system for a tracked vehicle according to the present invention are as follows:

[0052] 1. An electric drive system for a tracked vehicle with the motor and the reducer integrated into one.

[0053] 2. An electric drive system with a coaxial reducer, having a simple external shape, convenient for layout inside the vehicle, and facilitating the utilization of internal space.

[0054] 3. A motor drive system for a tracked vehicle with a large reduction ratio, including a housing, a motor, a reduction mechanism, etc. The housing is a relatively stationary part without rotation, and is connected to the vehicle body and the chassis through suspension. The motor includes a stator and a rotor. The stator is fixedly installed on the housing, and the rotor shaft (motor shaft) is the output shaft of the motor torque and is connected to the input shaft of the reduction mechanism. The input shaft of the reduction mechanism is connected to the central / fixed-axis gear (sun gear), and the central gear (sun gear) meshes with several planet gears; each planet gear rotates around its own axis, and the axis is installed on the planet carrier and revolves around the axis of the planet carrier; the planet carrier rotates around its own axis, but no physical shaft is required, nor is bearing support required; these several planet gears also mesh with an internal gear ring (support gear), and the internal gear ring is fixed on the housing; each planet gear is coaxially fixedly connected to another gear and rotates at the same speed; the secondary of the planet gear meshes with a second internal gear ring (output gear ring), and the second gear ring (output gear ring) is the output shaft of the reduction mechanism; the output shaft is connected to the tracked drive wheel to drive the vehicle.

[0055] 4. Adopting a wet multi-disc brake and integrating it with the motor and the coaxial reducer with a large reduction ratio greatly improves the system integration degree and reduces the space occupied by the electric drive and the brake.

[0056] The beneficial effects of the present invention are as follows:

[0057] Compared with a system where the motor, the reducer, and the brake are separated, this system integrates the three into one, and has a small volume.

[0058] Comparing with the reduction mechanism of parallel-axis transmission, the coaxial reducer is adopted in the present invention, which has a large transmission density, small size, regular shape, is easy to be installed and arranged inside the vehicle, and occupies a small space.

[0059] Comparing with the single-row planetary gear reduction mechanism: the reduction ratio of the single-row planetary gear is restricted by the system structure and the processing technology of parts, generally not exceeding 5 (i.e., 5:1); this system can achieve a much larger reduction ratio. The electric drive system of the tracked vehicle of the present invention has a reduction ratio of 15-40 or even higher. The requirements for the matching motor are reduced, the motor torque is smaller, the speed is increased, and the cost, volume and weight of the motor are reduced, and the efficiency is increased.

[0060] Embodiment 2:

[0061] Please refer to Figure 4 , an electric drive system for a tracked vehicle, which includes a housing 1, a motor and a coaxial reducer, and the motor and the coaxial reducer are integrated in the housing; the motor includes a stator 2 and a rotor 3. Different from Embodiment 1, the coaxial reducer adopts two-stage planetary gears, and each stage of planetary gears has a reduction ratio of 3-5 times. The output shaft of the previous stage is used as the input shaft of the next stage; the two stages are connected in series, and the reduction ratios are multiplied to obtain a reduction ratio of 10-25 times. Each stage of planetary gears includes a sun gear, a planet carrier, planetary gears and a supporting ring gear. For example, the previous stage of planetary gears includes a matched sun gear 6, planetary gears 7, a planet carrier 8 and a front supporting ring gear 9, and the secondary planetary gears include a matched rear sun gear 14, rear planetary gears 15, a rear planet carrier 16 and a rear supporting ring gear 17. The output shaft of the rear planet carrier is used as the output shaft 12 of the system.

[0062] Please refer to Figure 5 , the vehicle brake can be integrated into the motor drive system. Specifically, a brake 13 can be installed on the input shaft or the output shaft 12, and the brake 13 is preferably a wet multi-disc brake. Or a brake can be installed on the planet carrier 8 of the first stage of planetary gears.

[0063] As described above, only the embodiments using the technical content of this creation are provided. Any modification and change made by those skilled in the art using this creation fall within the scope of the patent claimed by this creation, rather than being limited to those disclosed in the embodiments.

Claims

1. An electric drive system for a tracked vehicle, characterized in that: It includes a housing, a motor and a coaxial reducer, and the motor and the coaxial reducer are integrated within the housing; The motor includes a motor shaft which is the torque output end of the motor and is connected to the input shaft of the reducer; The coaxial reducer is a planetary gear reduction mechanism. The planetary gear reduction mechanism includes an input shaft and an output shaft, and the output shaft is connected to the crawler drive wheel; The motor shaft, the input shaft and the output shaft are coaxial.

2. The electric drive system for a tracked vehicle according to claim 1, wherein: The planetary gear reduction mechanism includes a sun gear, a plurality of planetary gears, a planet carrier, a support ring gear, and an output ring gear. The sun gear is connected to the input shaft, and this input shaft is connected to the motor shaft; The shafts of the planetary gears are installed on the planet carrier. The planetary gears rotate around their own shafts and at the same time revolve around the axis of the planet carrier with the shaft; The planetary gears cooperate with the support ring gear and the output ring gear respectively, and the output ring gear is connected to the output shaft for torque output.

3. The electric drive system for a tracked vehicle according to claim 2, wherein: The planetary gear includes a first gear and a second gear fixedly connected coaxially. The first gear meshes with the support ring gear, and the support ring gear is fixed. The second gear meshes with the output ring gear, and the output ring gear is connected to the output shaft to form the output shaft of the reduction mechanism.

4. A tracked vehicle electric drive system according to claim 1, characterized in that: A vehicle brake is provided on the input shaft or the output shaft or the planet carrier shaft of the coaxial reducer. The brake is integrated with the motor and the coaxial reducer to improve the system integration degree and reduce the space occupied by the electric drive and the brake.

5. The electric drive system of a tracked vehicle according to claim 4, characterized in that: The vehicle brake adopts a wet multi-disc brake.

6. A tracked vehicle electric drive system according to any one of claims 1 to 4, characterized in that: The working process of the crawler vehicle electric drive system is as follows: The motor includes a stator and a cooperating rotor. The motor rotor outputs torque, which is transmitted through the motor shaft to the sun gear. The sun gear meshes with the first gear of the planetary gear and acts on the meshing point; The first gear meshes with the support ring gear. Since the rotational speed of the support ring gear is zero, the speed of the meshing point is zero, which is called the instantaneous center of motion; The second gear of the planetary gear is fixedly connected coaxially with the first gear and moves with it; The second gear meshes with the output ring gear, and the meshing point of the output ring gear moves along the tangent direction; The output ring gear is connected to the output shaft and drives the output shaft to rotate; Input / output speed ratio of the crawler vehicle electric drive system: Among them, the number of teeth or effective radius of the sun gear is represented by S; the number of teeth or effective radius of the first gear is represented by P1; the number of teeth or effective radius of the second gear is represented by P2; the rotational speed of the sun gear is n S , and the rotational speed of the output ring gear is n R2 .

7. The electric drive system for a tracked vehicle according to claim 1, wherein: The planetary gear reduction mechanism is a two-stage planetary gear mechanism. The output shaft of the previous stage planetary gear mechanism serves as the input shaft of the next stage planetary gear mechanism; The two-stage planetary gear mechanisms are connected in series, and the speed ratios are multiplied.

8. The electric drive system for a tracked vehicle according to claim 7, characterized in that: It also includes a vehicle brake, and the vehicle brake is integrated in the motor drive system.

9. The electric drive system for a tracked vehicle according to claim 8, characterized in that: A vehicle brake is installed on the input shaft or the output shaft of the coaxial reducer, or a brake is installed on the planet carrier of the first stage planetary gear.

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