A wire braking device, braking system and braking method based on a corner module

Abstract

The present invention discloses a wire-controlled braking device, a braking system and a braking method based on an angular module, belonging to the technical field of vehicle engineering. The wire-controlled braking device includes a brake disc, a plurality of guiding and fixing rods, a friction assembly, a lead screw nut and a lead screw motor; the brake disc is fixed inside the hub bearing housing and rotates with the wheel; the friction assembly is arranged between the brake disc and the steering knuckle; the guiding and fixing rods pass through the friction assembly, one end is fixed to the hub bearing stator, and the other end is fixed to the steering knuckle; the lead screw nut is fixed inside the friction assembly; the lead screw motor is fixed inside the steering knuckle, and the lead screw is threadedly connected to the lead screw nut; when the lead screw of the lead screw motor rotates, the lead screw nut drives the friction assembly to move along the guiding and fixing rods; when the friction assembly moves to abut against the inner side surface of the brake disc, the brake disc is braked, and when the friction assembly disengages from the inner side surface of the brake disc, the brake disc can rotate with the wheel. The present invention has the advantages of high space utilization rate, fast braking response and long service life.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle engineering, and relates to a vehicle braking structure, in particular to a wire-controlled braking device, a braking system and a braking method based on an angular module. Background Art

[0002] Traditional vehicle braking systems generally adopt mechanical friction braking methods, and their technical paths are mainly divided into two typical structures: hydraulic drive type and electromechanical drive type. In a hydraulic braking system, an axial thrust is generated by a hydraulic cylinder to drive a piston caliper to clamp and friction a brake disc; while in an electromechanical braking system, a motor drive is used to replace the hydraulic actuator, and the motor torque is converted into a caliper clamping force through a reduction mechanism. Although the drive methods are different, both of the above two types of braking systems need to arrange braking execution components including piston calipers and drive mechanisms on the radial periphery of the brake disc.

[0003] With the rapid development of in-wheel motor technology, the spatial layout of the braking system faces new challenges. Since the stator assembly of the in-wheel motor needs to occupy the core space inside the wheel hub, the traditional caliper brakes arranged along the periphery of the brake disc have inherent defects such as too large axial dimensions and insufficient radial envelope space, and it is difficult to be effectively integrated into the limited structural space of the in-wheel motor. Especially in four-wheel independent steering vehicles, the wheels need to achieve large-angle steering deflection (usually exceeding ±90°), and the traditional external caliper structure is extremely prone to movement interference with surrounding components such as suspension components and wheel arch linings during the steering process, which seriously restricts the degree of freedom design of the steering system and the optimization of the overall vehicle space layout.

[0004] Currently, the improvement solutions in the industry for this technical bottleneck mostly focus on the local optimization of the caliper structure, but limited by the inherent structure of the traditional brake, the core problems of high space occupancy rate of the braking unit and coexistence of dynamic interference risks have not been fundamentally solved. Summary of the Invention

[0005] The present invention provides a wire-controlled braking device, a braking system and a braking method based on an angular module to overcome the defects of the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a wire-controlled braking device based on a corner module for wheel braking. A hub motor drives the wheel to rotate through a hub bearing rotor; a kingpin steering gear drives the wheel to turn through a steering knuckle. The wire-controlled braking device includes a brake disc, a plurality of guiding and fixing rods, a friction assembly, a lead screw nut, and a lead screw motor; the brake disc is fixed on the inner side of the hub bearing housing and rotates with the wheel; the friction assembly is arranged between the brake disc and the steering knuckle; the guiding and fixing rods pass through the friction assembly, with one end fixed to the hub bearing stator and the other end fixed to the steering knuckle; the lead screw nut is fixed on the inner side of the friction assembly; the lead screw motor is fixed on the inner side of the steering knuckle, and the lead screw is in threaded connection with the lead screw nut; when the lead screw of the lead screw motor rotates, the lead screw nut drives the friction assembly to move along the guiding and fixing rods; when the friction assembly moves to abut against the inner side surface of the brake disc, the brake disc is braked, and when the friction assembly disengages from the inner side surface of the brake disc, the brake disc can rotate with the wheel.

[0008] In the present invention, the inner side and the outer side refer to, based on the whole vehicle, the direction towards the vehicle center is the inner side, and the direction away from the vehicle center is the outer side.

[0009] Further, the friction assembly includes a friction disc and a plurality of friction plates; the plurality of friction plates are fixed on the outer side surface of the friction disc; the lead screw nut is fixed on the inner side surface of the friction disc; the plurality of friction plates move synchronously with the lead screw nut through the friction disc; when the plurality of friction plates move to abut against the inner side surface of the brake disc, the brake disc is braked, and when the plurality of friction plates disengage from the inner side surface of the brake disc, the brake disc can rotate with the wheel.

[0010] Further, it further includes a resolver; the resolver is fixed on the inner side of the hub bearing stator to detect the position of the hub bearing rotor, thereby obtaining the rotational speed of the wheel.

[0011] Further, the brake disc is annular and sleeved around the hub bearing stator; the friction disc is annular and sleeved around the resolver; a flange is circumferentially fixed on the lead screw nut and fixed to the inner side surface of the friction disc through the flange, and the guiding and fixing rods pass through the flange; the lead screw nut passes through the center of the steering knuckle inward; the lead screw motor is equipped with a lead screw motor support frame and is fixed at the center of the inner side of the steering knuckle through the lead screw motor support frame and is located inside the lead screw nut.

[0012] Further, balls are provided between the threads of the lead screw nut and the lead screw.

[0013] Further, the lead screw motor is an electromagnetic braking motor. When the lead screw motor is powered off, the lead screw is firmly locked through electromagnetic braking to prevent the lead screw motor from sliding naturally due to the working load or moving horizontally due to external force when powered off, and to maintain the working stop in the original position; when powered on, the lead screw is released in time without affecting the normal operation of the lead screw motor.

[0014] Second aspect, the present invention further provides a vehicle braking system, including a hub motor braking unit. The hub motor braking unit includes a hub motor, which is connected to the vehicle's battery and can achieve regenerative braking, recovering energy while braking, and the recovered energy can charge the battery; the braking system further includes the above-mentioned wire-controlled braking device based on the angular module; the wire-controlled braking device realizes mechanical friction braking by moving the friction assembly.

[0015] Further, the hub motor braking unit further includes a capacitor and an energy release assembly; the hub motor is connected to the capacitor, and the energy recovered by the motor braking can charge the capacitor; the capacitor charges the energy release assembly, and the energy release assembly releases energy.

[0016] Further, the energy release assembly includes the vehicle's PTC, water tank, water pump, pipeline and fan; the water tank and the water pump are connected by a pipeline to form a cooling circuit, and the coolant is circulated in the cooling circuit by the water pump; the PTC heats the coolant in the pipeline; the fan dissipates heat from the coolant in the water tank; the capacitor supplies power to the water pump, PTC and fan.

[0017] Third aspect, the present invention further provides a braking method for the above-mentioned vehicle braking system: when the rotational speed of the wheel is in the constant torque region rotational speed of the hub motor, mechanical friction braking is performed through the wire-controlled braking device; when the rotational speed of the wheel is in the constant power region rotational speed of the hub motor: if the SOC is lower than the braking energy recovery limit value, the energy recovered by the motor braking charges the vehicle's battery; if the SOC is higher than the braking energy recovery limit value, the energy recovered by the motor braking charges the capacitor, and at the same time the water pump drives the coolant to circulate in the cooling circuit, the PTC heats the coolant in the pipeline, and the fan dissipates heat from the coolant in the water tank; if the SOC is higher than the braking energy recovery limit value and the capacitor reaches its rated capacitance, mechanical friction braking is performed through the wire-controlled braking device.

[0018] The beneficial effects of the present invention are as follows: The present invention provides a wire-controlled braking device based on an angular module, which realizes the arrangement of the wire-controlled braking system within the limited space of the angular module, effectively improving the space utilization rate of the angular module, and shortening the braking response time compared with hydraulic drive. Specifically, the present invention installs the driving part of the wire-controlled braking device in the center of the brake disc, and the friction plate and the friction disc are arranged at the edge of the brake disc to generate braking force by friction, so that the wire-controlled braking device can be installed inside the hub motor, improving the space utilization rate of the wheel.

[0019] The present invention also provides a braking system that has both service braking and parking braking functions. By implementing the braking function through the braking method, it can reduce unnecessary wear of the friction linings, extend the service life of the friction linings, and reduce energy loss of the vehicle. Specifically, during the braking process, the energy recovered by the hub motor braking is used for coolant circulation, PTC heating of the coolant, and coolant heat dissipation, improving the proportion of the motor braking function of the hub motor, thereby avoiding the problem of brake failure caused by thermal recession of the friction disc due to long-term mechanical friction braking. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a by-wire braking device based on an angular module;

[0021] Figure 2 is an exploded view of the structure of a by-wire braking device based on an angular module (excluding the guide fixing rod);

[0022] Figure 3 is a sectional view of a by-wire braking device based on an angular module;

[0023] Figure 4 is a schematic structural diagram of a partial hub motor braking unit;

[0024] The reference numerals in the drawings are: 11, hub bearing rotor; 12, rim connection bolt; 13, hub bearing housing; 14, hub bearing stator; 2, steering knuckle; 3, brake disc; 4, guide fixing rod; 5, friction assembly; 51, friction disc; 52, friction lining; 6, lead screw nut; 61, flange; 7, lead screw motor; 71, lead screw motor support frame; 8, resolver; 91, capacitor; 92, PTC; 93, water tank; 94, water pump; 95, pipeline; 96, fan. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following will describe the specific embodiments of the present invention with reference to the drawings.

[0026] As Figures 1 to 3 shown, this embodiment provides a by-wire braking device based on an angular module for wheel braking, which is arranged on the hub bearing and the steering knuckle 2 of the wheel.

[0027] The in-wheel motor drives the wheel to rotate through the hub bearing rotor 11. Specifically, a number of rim connection bolts 12 are fixed on the hub bearing rotor 11, and the rim connection bolts 12 pass through the hub bearing housing 13 to connect the in-wheel motor rotor with the rim of the wheel. The wheel, the in-wheel motor hub bearing and their connection methods are all prior arts and will not be elaborated here. The kingpin steering gear drives the wheel to turn through the steering knuckle 2. Specifically, the kingpin steering gear housing is connected to the suspension, the output shaft is fixed on the steering knuckle 2, and the output shaft drives the steering knuckle 2 to rotate, thereby driving the angle module to achieve steering. The lower end of the steering knuckle 2 is connected to the suspension through a ball joint.

[0028] As Figures 1 to 3 shown, the wire-controlled braking device includes a brake disc 3, a number of guide fixing rods 4, a friction assembly 5, a lead screw nut 6 and a lead screw motor 7.

[0029] The brake disc 3 is fixed on the inner side of the hub bearing housing 13 and rotates with the wheel. The friction assembly 5 is arranged between the brake disc 3 and the steering knuckle 2. The guide fixing rods 4 pass through the friction assembly 5, one end is fixed to the hub bearing stator 14 that does not rotate with the wheel, and the other end is fixed to the steering knuckle 2. That is, the guide fixing rods 4 fix the steering knuckle 2 on the hub bearing stator 14, and transfer the wheel force to the steering knuckle 2 and then to the suspension through the kingpin steering gear housing and the ball joint. The friction assembly 5 can move along the guide fixing rods 4.

[0030] The lead screw nut 6 is fixed on the inner side of the friction assembly 5. The lead screw motor 7 is fixed on the inner side of the steering knuckle 2, and the lead screw is threadedly connected to the lead screw nut 6. When the lead screw of the lead screw motor 7 rotates, the lead screw nut 6 drives the friction assembly 5 to move along the guide fixing rods 4 accordingly. When the friction assembly 5 moves to abut against the inner side surface of the brake disc 3, the brake disc 3 is braked; when the friction assembly 5 disengages from the inner side surface of the brake disc 3, the brake disc 3 can rotate with the wheel.

[0031] Specifically, the friction assembly 5 includes a friction disc 51 and a number of friction pads 52. A number of friction pads 52 are fixed on the outer side surface of the friction disc 51. The lead screw nut 6 is fixed on the inner side surface of the friction disc 51. A number of friction pads 52 move synchronously with the lead screw nut 6 through the friction disc 51. When a number of friction pads 52 move to abut against the inner side surface of the brake disc 3, the brake disc 3 is braked; when a number of friction pads 52 disengage from the inner side surface of the brake disc 3, the brake disc 3 can rotate with the wheel.

[0032] The brake disc 3 is annular and sleeved around the hub bearing stator 14. The friction disc 51 is annular and sleeved around the resolver 8. As Figure 2As shown in the figure, a flange 61 is circumferentially fixed to the lead screw nut 6. The flange 61 is fixed to the inner side of the friction disc 51, and the guiding fixed rod 4 passes through the flange 61. The relative positions of the friction disc 51 and the lead screw nut 6 are ensured to be unchanged by the flange 61, and axial movement is achieved on the guiding fixed rod 4. The lead screw nut 6 passes through the center of the steering knuckle 2 inward. The lead screw motor 7 is equipped with a lead screw motor support frame 71, which is fixed to the center inside the steering knuckle 2 through the lead screw motor support frame 71 and is located inside the lead screw nut 6.

[0033] Preferably, balls are provided between the threads of the lead screw nut 6 and the lead screw to reduce the frictional force between the lead screw nut 6 and the lead screw through the balls, making the axial movement of the lead screw nut 6 smoother.

[0034] The wire-controlled braking device further includes a resolver 8. The resolver 8 is fixed to the inner side of the hub bearing stator 14 to detect the position of the hub bearing rotor 11, thereby obtaining the rotational speed of the wheel. A resolver wiring harness hole is provided on the friction disc 51, and the wiring harness of the resolver 8 passes through the resolver wiring harness hole on the friction disc 51 and is connected to the MCU (hub motor control unit).

[0035] The lead screw motor 7 is an electromagnetic braking motor. When the lead screw motor 7 is powered off, the lead screw is firmly locked by electromagnetic braking to prevent the lead screw motor 7 from sliding naturally due to the working load or moving horizontally under external force when powered off, and to maintain the working stop in the original position. After being powered on, the lead screw is released in time without affecting the normal operation of the lead screw motor 7.

[0036] When the VCU (vehicle control unit) issues a braking command, the lead screw motor 7 drives the lead screw to perform a rotational movement, and the lead screw nut 6 converts the rotational movement of the lead screw into a linear movement in the axial direction of the lead screw nut 6, thereby driving the friction disc 51 to perform an axial movement. When the friction plate 52 on the friction disc 51 contacts the brake disc 3 and is axially extruded under the drive of the lead screw motor 7, the braking effect is achieved.

[0037] This embodiment also provides a vehicle braking system, including the above-mentioned wire-controlled braking device and a hub motor braking unit. The wire-controlled braking device realizes mechanical friction braking by moving the friction assembly 5. The hub motor braking unit includes a hub motor. The hub motor is connected to the vehicle's battery and can achieve regenerative braking, that is, energy is generated during braking and the energy is recovered, and the recovered energy can charge the vehicle's battery. The regenerative braking of the hub motor is a prior art and will not be elaborated here.

[0038] As Figure 4 shown, the hub motor braking unit further includes a capacitor 91 and an energy release component fixed to the suspension. The hub motor is connected to the capacitor 91, and the energy recovered by the motor braking can charge the capacitor 91. The capacitor 91 charges the energy release component, and the energy release component releases energy.

[0039] As Figure 4 shown, specifically, the energy release component includes the PTC (positive temperature coefficient thermistor) 92 of the vehicle, the water tank 93, the water pump 94, the pipeline 95, and the fan 96. The water tank 93 and the water pump 94 are connected through the pipeline 95 to form a cooling circuit, and the coolant is circulated in the cooling circuit by the water pump 94. The PTC 92 heats the coolant in the pipeline 95. The fan 96 dissipates heat from the coolant in the water tank 93. The capacitor 91 supplies power to the water pump 94, the PTC 92, and the fan 96.

[0040] This embodiment also provides a braking method for the above vehicle braking system, which is specifically as follows:

[0041] When the rotational speed of the wheel is in the constant torque region rotational speed of the in-wheel motor, mechanical friction braking is performed through the wire control braking device. That is, when the vehicle speed is relatively low, only mechanical friction braking is performed. After the VCU calculates the torque of the lead screw motor 7, separate mechanical friction braking control is achieved for each wheel, thereby avoiding the problem that the braking torque is large due to the large torque of the motor external characteristic curve at a relatively low rotor rotational speed, which in turn causes poor comfort for the passengers.

[0042] When the rotational speed of the wheel is in the constant power region rotational speed of the in-wheel motor:

[0043] If the SOC (state of charge of the battery) is lower than the braking energy recovery limit value, the energy recovered by the motor braking charges the vehicle's battery.

[0044] If the SOC is higher than the braking energy recovery limit value, the energy recovered by the motor braking charges the capacitor 91. At the same time, the water pump 94 drives the coolant to circulate in the cooling circuit, the PTC 92 heats the coolant in the pipeline 95, and the fan 96 dissipates heat from the coolant in the water tank 93. That is, the energy recovered by the motor braking is released through the capacitor 91 and the energy release component to reduce the mechanical friction braking performed by the wire control braking device, and avoid braking failure caused by the thermal decay of the friction disc 51 during long-term mechanical friction braking.

[0045] If the state of charge (SOC) is higher than the limit of regenerative braking energy and the capacitor 91 reaches its rated capacitance, mechanical friction braking is performed through the wire-controlled braking device. In such operating conditions, brake disc 3 heat fade is likely to occur, and reasonable braking distribution is required. Specifically: when the vehicle control unit (VCU) does not receive a signal of large-angle steering of the steering wheel, it is defaulted that braking is only required on a large turning radius or a straight track. The VCU controls two diagonal wheels as a group, and the VCU controls the two groups of wheels to perform mechanical friction braking alternately. When the brake disc 3 of one group of wheels shows heat fade, the other group of wheels is controlled to brake; when the VCU receives the steering wheel angle signal, that is, when the vehicle is performing braking and steering, the VCU controls the two front wheels and the two rear wheels as a group respectively, and controls the two groups of wheels to perform mechanical friction braking alternately. One group of wheels brakes while the other group steers. When the brake disc 3 of one group of wheels shows heat fade, that group of wheels is controlled to steer, and the other group of wheels brakes.

[0046] When both electric motor braking and mechanical friction braking fail, the VCU realizes redundancy of braking and steering by controlling the steering of the wheels.

[0047] When performing service braking: when the VCU does not receive a signal of large-angle steering of the steering wheel, it is defaulted that braking is only required on a large turning radius or a straight track. Then the VCU controls the front wheels and the rear wheels to turn inward simultaneously. The larger the angle of inward turning, the more obvious the braking effect. When the VCU receives the steering wheel angle signal, the VCU controls the front wheels to turn inward, and the rear wheels maintain the steering function to provide the side force required by the vehicle.

[0048] When performing parking braking: the VCU controls the front wheels to turn outward respectively and the rear wheels to turn inward respectively to achieve parking.

[0049] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art.

[0050] It should be noted that the terms such as "up", "down", "left", "right", "front", "rear", etc. cited in the invention are only for the convenience of clear description and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0051] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A brake-by-wire device based on an angle module, used for wheel braking; a wheel hub motor drives the wheel to rotate via a wheel hub bearing rotor (11); a kingpin steering gear drives the wheel to steer via a steering knuckle (2); characterized in that: The wire-controlled brake device comprises a brake disc (3), a plurality of guide fixing rods (4), a friction assembly (5), a screw nut (6) and a screw motor (7); The brake disc (3) is fixed to the inner side of the wheel hub bearing housing (13) and rotates with the wheel; The friction component (5) is arranged between the brake disc (3) and the steering knuckle (2); The guide fixing rod (4) passes through the friction assembly (5), one end of which is fixed to the wheel hub bearing stator (14), and the other end of which is fixed to the steering knuckle (2); The screw nut (6) is fixed on the inner side of the friction assembly (5); The screw motor (7) is fixed on the inner side of the steering knuckle (2), and the screw is threadedly connected to the screw nut (6); The screw of the screw motor (7) rotates, and the screw nut (6) drives the friction component (5) to move along the guide fixing rod (4); when the friction component (5) moves to abut against the inner side of the brake disc (3), the brake disc (3) is braked, and when the friction component (5) is separated from the inner side of the brake disc (3), the brake disc (3) can rotate with the wheel; The friction assembly (5) comprises a friction disc (51) and a plurality of friction plates (52); the plurality of friction plates (52) are fixed on the outer side surface of the friction disc (51); the screw nut (6) is fixed on the inner side surface of the friction disc (51); the plurality of friction plates (52) move synchronously with the screw nut (6) through the friction disc (51); when the plurality of friction plates (52) move to abut against the inner side surface of the brake disc (3), the brake disc (3) is braked; when the plurality of friction plates (52) are detached from the inner side surface of the brake disc (3), the brake disc (3) can rotate with the wheel; It also includes a rotary transformer (8); the rotary transformer (8) is fixed on the inner side of the wheel hub bearing stator (14) to detect the position of the wheel hub bearing rotor (11); The brake disc (3) is annular and is sleeved around the wheel hub bearing stator (14); the friction disc (51) is annular and is sleeved around the rotary transformer (8); a flange (61) is fixed to the circumference of the screw nut (6), and is fixed to the inner side of the friction disc (51) through the flange (61), and the guide fixing rod (4) passes through the flange (61); the screw nut (6) passes inward through the center of the steering knuckle (2); the screw motor (7) is equipped with a screw motor support frame (71), which is fixed to the center of the inner side of the steering knuckle (2) through the screw motor support frame (71) and is located on the inner side of the screw nut (6).

2. The brake-by-wire device based on the corner module according to claim 1, characterized in that: A ball is provided between the screw nut (6) and the thread of the screw.

3. The brake-by-wire device based on the corner module according to claim 1, characterized in that: The screw motor (7) is an electromagnetic brake motor.

4. A vehicle braking system, comprising a wheel hub motor braking unit, the wheel hub motor braking unit comprising a wheel hub motor, the wheel hub motor being connected to a vehicle battery, capable of achieving regenerative braking, recovering energy while braking, and the recovered energy being capable of charging the battery; characterized in that: The braking system also includes a brake-by-wire device based on an angle module as described in any one of claims 1 to 3; the brake-by-wire device achieves mechanical friction braking by moving a friction component (5).

5. The vehicle braking system according to claim 4, characterized in that: The hub motor brake unit also includes a capacitor (91) and an energy release component; The wheel hub motor is connected to the capacitor (91), and the energy recovered by the motor braking can charge the capacitor (91); The capacitor (91) charges the energy-releasing component, and the energy-releasing component releases energy.

6. The vehicle braking system according to claim 5, characterized in that: The energy release assembly includes a vehicle PTC (92), a water tank (93), a water pump (94), a pipeline (95), and a fan (96); The water tank (93) and the water pump (94) are connected via a pipeline (95) to form a cooling circuit, and the coolant circulates in the cooling circuit via the water pump (94); The PTC (92) heats the coolant in the pipeline (95); The fan (96) dissipates heat from the coolant in the water tank (93); The capacitor (91) supplies power to the water pump (94), the PTC (92) and the fan (96).

7. The braking method of the vehicle braking system according to claim 6, characterized in that: When the rotation speed of the wheel is in the constant torque zone of the wheel hub motor, mechanical friction braking is performed through the wire control brake device; When the wheel speed is in the constant power range of the hub motor: If the SOC is lower than the braking energy recovery limit, the energy recovered by the motor braking is used to charge the vehicle's battery; If the SOC is higher than the braking energy recovery limit, the energy recovered by the motor braking charges the capacitor (91), and at the same time the water pump (94) drives the coolant to circulate in the cooling circuit, the PTC (92) heats the coolant in the pipeline (95), and the fan (96) dissipates the heat of the coolant in the water tank (93); If the SOC is higher than the braking energy recovery limit and the capacitor (91) reaches its rated capacity, mechanical friction braking is performed through the wire control brake device.

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