Engineering machinery running and parking integrated multi-stage braking rotation power assembly and control method thereof

Abstract

The invention discloses an engineering machinery running and parking integrated multi-stage braking rotation power assembly and a control method thereof, and belongs to the technical field of engineering machinery. The rotary power assembly is mainly composed of a rotary motor, a brake and a speed reducer, the brake is composed of a wet type multi-disc brake device and a hydraulic rotary damping device, and an electric brake-friction brake-hydraulic damping brake three-level brake is formed. The rotating speed of a rotating motor is monitored in real time to serve as a main control parameter, and before and after a braking mode switching critical point, a braking torque mapping algorithm based on rotating speed feedback is used for applying a gradually-changing slope (gradient) which is accurately calculated to output torque which exits from a braking source and is connected into the braking source, so that smooth transition of the total braking torque is achieved. The rotary system can be stably controlled, free switching of multiple braking modes can be achieved, and the problems that low-temperature energy is recycled, braking recycled energy is inconvenient to store, braking impact is restrained, and the braking modes are switched in a non-inductive mode are solved.

Description

TECHNICAL FIELD

[0001] The application relates to an engineering machine integrated multi-stage braking slewing power assembly and a control method thereof, and belongs to the technical field of engineering machines. BACKGROUND

[0002] As a multipurpose engineering machine, an excavator is often used for digging, land leveling, loading and the like, and has the characteristics of strong periodicity and frequent slewing action, and the external load is complex and changeable. In the slewing process, the excavator is prone to speed fluctuation, which will cause the motor to frequently switch between the high efficiency area and the low efficiency area. In this transient state, not only the power consumption increases significantly, but also the comfort of the driver will be poor.

[0003] The excavator electric slewing transmission usually adopts a single braking source (such as pure electric braking or pure friction braking), and the single braking source cannot simultaneously meet the braking performance requirements in all working conditions. The pure electric braking rapidly decays in braking torque at low speed, and cannot realize reliable parking; the energy recovery is limited at low temperature or full battery state.

[0004] At present, there are also technologies that simply superimpose multiple braking modes, but if the control is not proper, torque interference will occur, resulting in jerk or control instability. In addition, during the switching of the traditional braking mode (such as from motor braking to friction braking), the output torque of the actuator will change suddenly due to the step change of the control command. This torque mutation will be converted into an impact on the transmission system, causing mechanical vibration and abnormal noise, affecting the operation comfort; causing stress fatigue of the structure, reducing the service life of the key components (such as the reducer and the bearing); causing unstable operation, affecting the positioning accuracy of the machine in fine operation.

[0005] In addition, the excavator needs to work in an extremely low temperature environment, and below -10°C, the motor braking energy can only be forced to dissipate because the battery cannot be charged, so a dissipative resistance grid is usually additionally installed. When the excavator battery is full SOC, the power battery also cannot be charged, and the slewing motor braking recovery energy is not convenient to store. SUMMARY

[0006] The purpose of the present application is to provide an engineering machine integrated multi-stage braking slewing power assembly and a control method thereof, which realizes the slewing transmission control of the excavator through a three-stage braking structure of electric braking-friction braking-hydraulic damping and a torque gradient cutting algorithm based on speed feedback, and solves the problems of low-temperature energy recovery, inconvenient storage of braking recovery energy, braking impact suppression, and modeless switching.

[0007] To achieve the above-mentioned purpose / to solve the above-mentioned technical problems, the present application adopts the following technical solutions:

[0008] In a first aspect, the application provides an integrated multi-stage braking slewing power assembly of a construction machine, comprising a slewing motor, a wet multi-plate brake, a hydraulic rotary damper, a speed reducer, a power output shaft, a valve group, an accumulator, a low-pressure electronic pump and a power battery; one end of the slewing motor is connected to one end of the wet multi-plate brake, the other end of the wet multi-plate brake is connected to one end of the hydraulic rotary damper, the other end of the hydraulic rotary damper is connected to the speed reducer, and the speed reducer is connected to a slewing platform through the power output shaft; the oil inlet of the valve group is connected to a hydraulic oil tank through the low-pressure electronic pump, and the oil outlets of the valve group are respectively connected to the accumulator, the wet multi-plate brake, the hydraulic rotary damper and the power battery.

[0009] In combination with the first aspect, further, the wet multi-plate brake comprises a spring, a plurality of sets of dynamic and static friction plates, a hydraulic cylinder, a bearing, a spline and a housing.

[0010] The spline comprises an outer spline and an inner spline, the plurality of sets of dynamic and static friction plates comprise a dynamic friction plate and an outer friction plate, the outer spline is located on an extension section of a motor output shaft of the slewing motor, the inner spline is located in an inner hole of the dynamic friction plate, the dynamic friction plate is engaged with the outer spline on the motor shaft through the inner spline to rotate together with the motor shaft, and the static friction plate is engaged with the inner spline on the housing through the outer spline; the hydraulic cylinder is located in an annular piston cavity in the housing, and the spring is installed on a piston or a pressure disc of the hydraulic cylinder; the bearing is located between the housing and the motor shaft of the slewing motor or the pressure disc of the hydraulic cylinder.

[0011] The brake cavities of the hydraulic cylinder and the dynamic and static friction plates are respectively connected to the valve group.

[0012] In combination with the first aspect, further, the hydraulic rotary damper comprises a planetary gear, an internally meshing gear pump and an electric proportional overflow valve.

[0013] The planetary gear mechanism comprises a sun gear, a planet carrier and a ring gear, the sun gear is connected to the internally meshing gear pump, the planet carrier is fixed to the housing of the slewing power assembly through a bearing, and the ring gear is connected to the housing of the wet multi-plate brake; the internally meshing gear pump comprises a pump shaft, a pinion and an inner ring gear, the pump shaft is coaxially connected to the sun gear, the pinion is installed on the pump shaft to rotate at a high speed with the pump shaft, and the inner ring gear is fixed in a pump body of the internally meshing gear pump to form an internally meshing relationship with the pinion; the oil inlet of the electric proportional overflow valve is connected to the oil outlet of the internally meshing gear pump through a high-pressure oil pipe, and the oil return port of the electric proportional overflow valve is connected to the oil inlet of the internally meshing gear pump.

[0014] When the pump shaft is driven, the internally meshing gear pump converts the rotating mechanical energy into hydraulic energy, absorbs oil from the oil inlet and discharges pressure oil from the oil outlet.

[0015] In combination with the first aspect, further, the oil liquid in the hydraulic oil tank enters the valve group through the low-pressure electronic pump, the oil liquid flows into the accumulator, the hydraulic cylinder of the wet multi-plate brake and the dynamic-static friction plate brake cavity through the valve group, the oil liquid supplies oil for the hydraulic cylinder, the hydraulic cylinder acts to realize braking or unbraking, the oil liquid supplies oil for the dynamic-static friction plate brake cavity, the dynamic-static friction plate brake is cooled, and the hot oil flowing out of the accumulator, the hydraulic cylinder and the dynamic-static friction plate brake cavity flows back to the hydraulic oil tank through the valve group.

[0016] The internal gear pump of the hydraulic rotary damper absorbs oil from the hydraulic oil tank, the oil liquid flows into the electric proportional overflow valve to realize hydraulic rotary damping braking, and the hot oil flows back to the hydraulic oil tank through the valve group.

[0017] In combination with the first aspect, further, the hot oil flowing out of the accumulator, the hydraulic cylinder and the dynamic-static friction plate brake cavity flows to the power battery through the valve group, the power battery is heated, and the cold oil flows back to the hydraulic oil tank.

[0018] In combination with the first aspect, further, the rotary power assembly further comprises a motor controller, a vehicle controller and an operating handle, the operating handle is electrically connected to one end of the vehicle controller, and the other end of the vehicle controller is connected with the rotary motor through the motor controller.

[0019] The second aspect provides a control method of an engineering machinery line-station integrated multi-stage braking rotary power assembly.

[0020] The control instruction output by the operating handle is acquired through the vehicle controller;

[0021] In response to the control instruction, the rotary battery temperature, the rotary battery residual capacity and the rotary motor speed are acquired in real time, the braking mode of the rotary power assembly is selected according to the preset braking mode condition, and the rotary motor, the wet multi-plate brake or the hydraulic rotary damper is controlled to execute the braking operation according to the braking mode; the braking mode comprises motor braking, friction braking and hydraulic damping braking;

[0022] When the braking mode is switched, the output torque of the exiting braking source and the connected braking source is calculated by using a braking torque mapping algorithm based on speed feedback, and the braking source is switched according to the output torque.

[0023] In combination with the second aspect, further, the motor braking comprises a normal temperature mode I, a normal temperature mode II and a low temperature mode;

[0024] The current rotary battery temperature T is compared with the first temperature threshold T1 through the vehicle controller, and the current rotary battery residual capacity SOC is compared with the first capacity threshold S1; if T > T1 and SOC < S1, the normal temperature mode I is entered; if T > T1 and SOC > S1, the normal temperature mode II is entered; if T ≤ T1, the low temperature mode is entered.

[0025] The normal temperature mode I adopts regenerative braking; the normal temperature mode II adopts copper loss braking, and when T>second temperature threshold T2, the copper loss braking is stopped, and the electric braking is stopped; in the low temperature mode, the copper loss braking is automatically switched, and kinetic energy is converted into heat energy dissipation by controlling the short circuit of the motor three-phase winding or connecting the power resistor.

[0026] In combination with the second aspect, further, in the motor braking mode, when the rotating motor speed drops to a preset first speed threshold, a braking mode switching program is started to switch the braking mode from the motor braking to the friction braking, and a braking torque mapping algorithm based on speed feedback is used to calculate the output torque of the rotating motor for the motor braking and the wet multi-plate brake for the friction braking.

[0027] The output torque calculation formula of the rotating motor for the motor braking is:

[0028] T_motor_cmd(n) = T_motor_max * [ (n_current - n_low) / Δn ];

[0029] Wherein, T_motor_cmd(n) represents the function of the rotating motor torque about the motor speed n, T_motor_max represents the current command torque of the rotating motor, n_current represents the current rotating motor speed, n_low represents the lower limit speed of the switching interval from the motor braking to the friction braking, and Δn represents the switching interval from the motor braking to the friction braking.

[0030] The output torque calculation formula of the wet multi-plate brake for the friction braking is:

[0031] P_brake_cmd(n) = P_brake_max * [ 1 - (n_current - n_low) / Δn ) ];

[0032] Wherein, P_brake_cmd(n) represents the function of the wet multi-plate brake torque about the motor speed n, and P_brake_max represents the maximum friction braking torque.

[0033] When n_current <= n_low, the motor braking torque drops to 0, the friction braking pressure rises to P_brake_max, and the rotating power assembly completely enters the friction braking mode.

[0034] In combination with the second aspect, further, when the rotating motor speed drops to a second rotating speed threshold value, the hydraulic damping brake is started, the remaining kinetic energy of the rotating mechanism is enlarged through the planetary gear and drives the internal gear pump; the internal gear pump pumps the oil from the low-pressure cavity into the high-pressure cavity, flows through the electric proportional overflow valve to generate a controllable back pressure, and forms a damping torque proportional to the square of the pump rotating speed; when the motor speed is equal to 0 r / min, the hydraulic damping brake is released, the friction brake is kept, and parking is realized.

[0035] Compared with the prior art, the present application has the following beneficial effects:

[0036] The present application provides an engineering machinery integrated multi-stage braking rotating power assembly and a control method thereof. The rotating motor, the wet multi-plate brake and the hydraulic rotary damper are provided in the system. The motor brake, the friction brake (mechanical brake) and the hydraulic damping brake can be realized according to the actual braking demand, the multiple braking modes can be switched freely, the braking effect is improved, and the braking impact is avoided. The power battery is connected with the valve group. When the temperature of the power battery is too low, the motor braking heat, the brake heat and the hydraulic damping heat can be transferred to the power battery through the valve group to accelerate the temperature rise of the battery.

[0037] The present application constructs a three-stage braking sequence of "electric brake-friction brake-hydraulic damping" and a braking torque mapping algorithm based on rotating speed feedback to solve the existing engineering machinery damping impact problem, fully utilizes the respective advantages of electric brake, friction brake and hydraulic brake, realizes function complementation, realizes the whole process smooth braking from high speed to stop through the pre-set braking mode condition and torque gradient switching algorithm, realizes the whole process smooth braking from high speed to stop, reduces the impact degree of braking switching, and significantly improves the operation comfort and structural reliability. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Fig. 1 shows a structure schematic diagram of an engineering machinery integrated multi-stage braking rotating power assembly in an embodiment of the present application;

[0039] Figure 2 Fig. 3 shows a structure schematic diagram of a wet multi-plate brake in an embodiment of the present application;

[0040] Figure 3 Fig. 4 shows a structure schematic diagram of a hydraulic rotary damper in an embodiment of the present application;

[0041] Figure 4 Fig. 5 shows a hydraulic oil circuit schematic diagram of a rotating power assembly in an embodiment of the present application;

[0042] Figure 5 Fig. 6 shows a step schematic diagram of a control method of an engineering machinery integrated multi-stage braking rotating power assembly in an embodiment of the present application;

[0043] In the figure, 1 - rotary motor, 2 - wet multi-plate brake, 3 - hydraulic rotary damper, 4 - speed reducer, 5 - power output shaft, 6 - valve group, 7 - accumulator, 8 - low-pressure electronic pump, 9 - motor controller, 10 - vehicle controller, 11 - operating handle, 12 - pressure sensor, 13 - power battery, 14 - DC-DC converter, 15 - hydraulic oil tank, 21 - spring, 22 - multiple sets of dynamic and static friction plates, 23 - hydraulic cylinder, 24 - bearing, 25 - spline, 26 - housing, 31 - planetary gear, 32 - internally meshing gear pump, 33 - electric proportional overflow valve. DETAILED DESCRIPTION

[0044] The technical scheme of the present application will be described in detail below with reference to the drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, rather than limitations thereof. The technical features in the embodiments of the present application and the embodiments can be combined with each other without conflict.

[0045] Embodiment 1

[0046] This embodiment introduces an engineering machinery row-station integrated multi-stage braking rotary power assembly, as shown in Figure 1 The rotary motor 1, the wet multi-plate brake 2, the hydraulic rotary damper 3, the speed reducer 4, the power output shaft 5, the valve group 6, the accumulator 7, the low-pressure electronic pump 8, the motor controller 9, the vehicle controller 10, and the operating handle 11 are mainly included.

[0047] The rotary motor, the wet multi-plate brake, the hydraulic rotary damper, the speed reducer, and the power output shaft are mainly used to realize rotation and braking. The rotary motor is connected with the vehicle controller VCU through the motor controller, and rotates or brakes according to the control instruction issued. The wet multi-plate brake is mechanically connected with the rotary motor, and is mainly used to realize power rotation braking or composite braking in cooperation with the electric braking of the rotary motor and the hydraulic rotary damper. The hydraulic rotary damper is mechanically connected with the wet multi-plate brake, and is mainly used to reduce rotation impact and rotation deceleration or composite braking in cooperation with the electric braking of the rotary motor and the wet multi-plate brake. The power output shaft is mechanically connected with the hydraulic rotary damper through the speed reducer, the speed reducer plays a role of speed reduction and torque increase, and the power output shaft can output power to the rotary platform.

[0048] The valve group is connected with the wet multi-plate brake, the hydraulic rotary damper, the accumulator, and the low-pressure electronic pump, respectively, and distributes the oil in the oil circuits such as the wet multi-plate brake, the hydraulic rotary damper, the accumulator, the electronic pump, and the power battery heat dissipation by adjusting the valves in the valve group.

[0049] The low-pressure electronic pump is used to supply power for the wet multi-plate brake; at the start time, the accumulator pressure value is detected by the pressure sensor 12, if the lower limit of the pressure setting value is reached, the low-pressure electronic pump starts to supply power for the accumulator, meeting the working requirements of the wet multi-plate brake, if the upper limit of the pressure setting value is reached, the low-pressure electronic pump is stopped.

[0050] The driver outputs a control signal to the vehicle controller VCU by operating the handle, the vehicle controller VCU processes the control signal, and the motor controller receives the control instruction output by the vehicle controller to control the operation (rotation or braking) of the rotary motor.

[0051] The power battery 13 supplies power to each component in the device; the power battery is connected with a DC-DC converter (DCDC) 14, and the output voltage of the power battery can be adjusted through the DCDC.

[0052] As shown in Figure 2 The wet multi-plate brake mainly includes a spring 21, a plurality of sets of dynamic and static friction plates 22, a hydraulic cylinder 23, a bearing 24, a spline 25, and a shell 26.

[0053] The shell is the basic structural member and force-bearing member of the entire brake, and the two ends of the shell are rigidly connected with the output end of the rotary motor and the input end of the speed reducer through flanges and bolts, thereby forming a coaxial power assembly.

[0054] The spline includes an outer spline and an inner spline, the outer spline is machined on the extended section of the motor output shaft of the rotary motor, and the inner spline is located in the inner hole of a set of dynamic friction plates, the dynamic friction plates are engaged with the outer spline on the motor shaft through the inner spline, thereby rotating together with the motor shaft.

[0055] The plurality of sets of dynamic and static friction plates include a plurality of sets of dynamic friction plates and static friction plates, the dynamic friction plates are connected with the motor shaft through the spline and rotate with the shaft, and the outer edge of the static friction plate is engaged with the inner spline on the shell through the outer spline, that is, the static friction plate is fixed on the shell and only axially slides without rotating. The dynamic and static friction plates are alternately stacked together and jointly form a friction pair. In the non-braking state, there is a small gap between them.

[0056] The hydraulic cylinder is an annular piston cavity machined in the shell, when the pressure oil enters the cylinder, it pushes the internal annular piston, which directly or through a set of pressure plates axially pushes all the stacked dynamic and static friction plates, so as to press them tightly, thereby converting the rotational kinetic energy of the motor into heat energy through friction to realize braking.

[0057] The spring is a set of circumferentially distributed return springs installed on the piston or pressure plate of the hydraulic cylinder. When the oil pressure in the hydraulic cylinder is unloaded, the elastic force of the spring pushes the piston back to its original position, thereby releasing the pressing force on the dynamic and static friction plates, separating the friction plates, and releasing the braking state.

[0058] The bearing is located between the housing and the motor shaft or the pressure plate, which functions to support and position, ensuring that the internal moving parts (such as the piston, pressure plate) can smoothly move axially, while preventing them from being radially offset or rotating with the housing, ensuring the accuracy of the braking action.

[0059] The hydraulic connection relationship of the wet multi-plate brake includes:

[0060] Brake cavity oil circuit: the oil inlet of the hydraulic cylinder is connected to the valve group brake oil inlet on the housing through the internal oil channel. When the valve group supplies pressure oil, the brake implements braking.

[0061] Cooling / separation cavity oil circuit: the housing also has a dedicated cooling oil channel, whose oil inlet is connected to the valve group cooling oil inlet on the housing. It can directly spray or flow through the gap between the moving and static friction plates in the separation state, playing the roles of cooling (removing heat generated during braking), lubrication (reducing wear of the friction plates in the initial stage of engagement), cleaning and separation (the flow of oil helps to separate the friction plates and remove debris). Figure 3 As shown, the hydraulic rotary damper mainly includes a planetary gear 31, an internal meshing gear pump 32, and an electric proportional overflow valve 33.

[0062] The planetary gear mechanism further includes a sun gear 311, a planet carrier 312, and a ring gear 313. The ring gear is the input end of the planetary gear mechanism, and its outer edge is rigidly connected to the housing of the wet multi-plate brake through splines or bolts. Therefore, the rotational movement of the brake housing is directly transmitted to the ring gear. The planet carrier is the fixed end of the planetary gear mechanism, which is supported on the assembly housing through bearings and is circumferentially fixed (for example, connected to the housing through a pin or a key), so it cannot rotate and can only bear torque. The sun gear is the output end of the planetary gear mechanism, and its speed is amplified by the planetary mechanism. The sun gear output shaft is directly connected to the pump shaft of the internal meshing gear pump through splines or couplings.

[0063] The internal meshing gear pump further includes a pump shaft 321, a pinion 322, and an internal gear ring 323. The pump shaft is coaxially connected to the sun gear (311) of the planetary mechanism and receives the speed-up input. The pinion is installed on the pump shaft and rotates at high speed with the pump shaft. The internal gear ring is fixed in the pump body and forms an internal meshing relationship with the pinion.

[0064] The transmission relationship of the planetary gear to the internal meshing gear pump is: power flow is brake housing -> ring gear -> planet gear -> sun gear -> pump shaft.

[0065] When the pump shaft is driven, the internal meshing gear pump starts to work, which converts the rotating mechanical energy into hydraulic energy, sucking oil from the oil inlet (P1) and discharging pressure oil from the oil outlet (P2). At this time, it is no longer used as a power element, but as a damping element.

[0066] The inlet of the electro-proportional relief valve is connected to the outlet (P2) of the internal gear pump via a high-pressure oil pipe, and its return port is connected to the inlet (P1) of the internal gear pump, thus forming a closed hydraulic circulation loop.

[0067] The electro-proportional relief valve is used to set and regulate the system pressure of the aforementioned hydraulic circuit. Its set pressure value is proportional to the received control current.

[0068] In the rotary power assembly of this invention, the hydraulic circuit is connected as follows: Figure 4 As shown, the low-pressure electronic pump draws oil from the hydraulic tank, and the oil enters the valve assembly. Firstly, the oil flows through the valve assembly to the accumulator. Secondly, the oil supplies oil to the hydraulic cylinder of the wet multi-disc brake, supporting the cylinder's action to achieve braking or releasing the brake. Thirdly, the oil supplies oil to the braking chambers of the wet multi-disc brake's moving and stationary friction plates, supporting the braking and cooling of the moving and stationary friction plates. The hot oil flowing out of the accumulator, the hydraulic cylinder of the wet multi-disc brake, and the braking chambers of the moving and stationary friction plates flows back to the hydraulic tank through the valve assembly. The internal gear pump of the hydraulic rotary damper draws oil from the hydraulic tank and flows into the electro-proportional relief valve, achieving hydraulic rotary damping braking. The hot oil flows back to the hydraulic tank through the valve assembly. When the power battery temperature is too low, the control valve assembly directs the hydraulic oil flowing from the braking chambers of the wet multi-disc brake's moving and stationary friction plates and the electro-proportional relief valve to the power battery, heating the battery pack. The cold oil finally flows back to the hydraulic tank.

[0069] Compared to current mainstream solutions, the rotary powertrain of this invention adopts a three-stage braking system of electric braking, friction braking, and hydraulic damping, and optimizes braking control based on a braking torque mapping algorithm with speed feedback. It adds a motor copper loss braking mode (stator winding short circuit), and the integrated design of the hydraulic damping system and brake cooling oil circuit transfers the heat from motor braking, brake, and hydraulic damping to the power battery, accelerating the battery temperature recovery. It adopts a planetary gear coaxial drive internal meshing gear pump, and the wet brake and hydraulic damper oil circuits share the same hydraulic source, reducing system bulkiness.

[0070] Example 2

[0071] Based on the slewing powertrain described in Embodiment 1, this embodiment introduces a control method for a multi-stage braking slewing powertrain integrating travel and parking in engineering machinery, mainly involving a control method for switching different braking modes of the slewing powertrain. For example... Figure 5 As shown, the method of the present invention includes the following steps:

[0072] Step A, through the vehicle controller to obtain the command issued by the handle, in response to the driver operating handle issued by the rotary motor rotary command, through the vehicle controller to the motor controller to send acceleration / steady running instruction, through the vehicle controller to the valve group to send instructions, control the wet multi-plate brake to release the brake, through the vehicle controller to the electromagnetic proportional overflow valve to send instructions, control the electromagnetic proportional overflow valve to act, release the hydraulic rotary damper damping brake.

[0073] Step B, when the rotary motor rotates normally, the driver judges whether the rotary action is completed, if not, continue to operate the handle to issue the rotary command, if completed, swing the handle to issue the rotary motor braking command.

[0074] Step C, real-time acquisition of rotary battery temperature, rotary battery remaining power (SOC) and rotary motor speed, according to the preset braking mode condition, select the braking mode of the rotary power assembly, control the rotary motor, wet multi-plate brake or hydraulic rotary damper to execute the braking operation according to the selected braking mode, and when switching the braking mode (from motor braking to friction braking), the braking torque mapping algorithm based on speed feedback is used to calculate the output torque of the real-time exit braking source and the access braking source.

[0075] The application creatively constructs a three-stage braking sequence based on speed and temperature feedback, which works cooperatively. The sequence divides the braking process into three stages according to the speed domain, each stage is dominated by one braking source and assisted by other braking sources, to realize the maximum efficiency and optimal smoothness. Among them, the first stage is electric braking (Primary: Electric Braking), the second stage is friction braking (Secondary: Friction Braking), and the third stage is hydraulic damping braking (Tertiary: Hydraulic Damping Braking).

[0076] The specific operation of step C is as follows:

[0077] Step C01, in response to the rotary motor braking command, enter the motor braking mode, and use the rotary motor to execute the braking operation. In the motor braking mode, the motor controller calculates the required braking torque according to the pedal opening or the preset deceleration request, and the motor is preferentially provided.

[0078] The motor braking mode can be divided into three cases: through the vehicle controller to compare the current rotary battery temperature T with the first temperature threshold T1, and compare the current rotary battery remaining power SOC with the first power threshold S1; if the rotary battery temperature T > T1 and the rotary battery SOC < S1, enter the normal temperature mode I; if T > T1 and the battery SOC > S1, enter the normal temperature mode II; if T ≤ T1, enter the low temperature mode.

[0079] In the present application, the first temperature threshold T1 is preferably -10℃, and the first electric quantity threshold S1 is preferably 90%.

[0080] The normal temperature mode I uses regenerative braking, using the motor as a generator, and the recovered energy is charged to the battery or supplied to other power units. The normal temperature mode II uses copper loss braking, and when T>the second temperature threshold T2 (T2 is preferably 40℃), the copper loss braking is stopped, and the electric braking is stopped. In the low temperature mode, the copper loss braking (energy consumption braking) mode is automatically switched, and the kinetic energy is converted into heat energy dissipation by controlling the short circuit of the motor three-phase winding or connecting the power resistor, overcoming the bottleneck that the battery cannot be charged at low temperature.

[0081] Step C02, in the motor braking mode, when the rotating motor speed drops to a preset first speed threshold, the system starts the braking mode switching program, which needs to switch from the motor braking mode to the friction braking mode, and gradually uses the wet multi-plate brake to perform the braking operation. In the mode switching process, the output torque of the exiting braking source (rotating motor) and the accessing braking source (wet multi-plate brake) is calculated by using the braking torque mapping algorithm based on speed feedback. The first speed threshold is preferably 1050 r / min.

[0082] (1) Pre-pressure filling is performed. At the same time when the motor braking torque starts to decay by gradient, the hydraulic system supplies the pilot pressure to the wet multi-plate brake piston cavity, eliminates the gap between the friction plates (0.1-0.2 mm), and prepares for torque transmission.

[0083] (2) The braking torque mapping algorithm based on speed feedback controls the linear decay of the motor braking torque and the linear increase of the friction braking torque, completes the torque handover, realizes the seamless superposition of torque, and avoids impact.

[0084] In order to solve the problem that the traditional braking mode switching is easy to produce impact and instability, the present application monitors the rotating motor speed in real time as a representation of the system kinetic energy state, and uses it as the main control parameter. Before and after the critical point of the braking mode switching, a gradually changing slope (gradient) that is accurately calculated is applied to the output torque of the exiting braking source and the accessing braking source, instead of instantaneous switching, so as to realize the "seamless handover" of the torque and ensure the smooth transition of the total braking torque.

[0085] The present application defines the starting speed of the motor brake start weakening as n_high, which can be set to 1050 r / min according to experience; defines the target speed of the friction brake full access as n_low, which can be set to 950 r / min according to experience; defines the switching interval from the motor brake to the friction brake as Δn = n_high - n_low (100 r / min); defines the motor torque gradient as -K_motor (N•m / r / min), K_motor = ΔT_motor / Δn, ΔT_motor is the difference between the starting value and the end value of the motor torque in the switching interval; and defines the friction brake pressure gradient as +K_brake (MPa / r / min), which can be realized by controlling the oil pressure through an electric proportional overflow valve, K_brake = ΔP_brake / Δn, ΔP_brake is the difference between the starting value and the end value of the brake pressure in the switching interval.

[0086] Initialize the motor brake torque T_motor_cmd = T_motor_max (current motor command torque), and the friction brake torque P_brake_cmd = 0 (current brake command pressure).

[0087] The rotary motor speed data n_current is collected in real time through the motor speed encoder, and when n_current <=n_high, the brake torque mapping algorithm based on speed feedback is triggered.

[0088] After the system enters the switching interval, the command values of each executing component are dynamically calculated according to the current motor speed:

[0089] a) Motor brake torque decay curve:

[0090] T_motor_cmd(n) = T_motor_max * [ (n_current - n_low) / Δn ]

[0091] Wherein, T_motor_cmd(n) represents the function of the rotary motor torque with respect to the motor speed n.

[0092] b) Friction brake torque growth curve:

[0093] P_brake_cmd(n) = P_brake_max * [ 1 - (n_current - n_low) / Δn ) ]

[0094] Wherein, P_brake_cmd(n) represents the function of the wet multi-plate brake torque with respect to the motor speed n.

[0095] c) Total braking torque guarantee:

[0096] At any time, the total braking torque T_total should be approximately equal to the required braking torque at that speed to avoid under-braking or over-braking:

[0097] T_total ≈ T_motor_cmd(n) + T_brake(P_brake_cmd(n))

[0098] Where T_brake is the mechanical braking torque at the current speed.

[0099] In the switching interval between motor braking and friction braking, the calculated T_motor_cmd is sent to the motor controller, and the calculated P_brake_cmd is converted into a current signal and sent to the wet multi-plate brake valve group.

[0100] When n_current <= n_low, the motor braking torque drops to 0, the friction braking pressure rises to P_brake_max, the algorithm is executed, and the system completely enters the friction braking mode.

[0101] Step C03, in the friction braking mode, when the rotating motor speed further decreases to a second speed threshold, the hydraulic damping brake is started, and when the motor speed is equal to 0 r / min, the hydraulic damping brake is released, the friction brake is maintained, and the parking is realized. The second speed threshold is 100 r / min.

[0102] The working mechanism of the hydraulic damping brake is: the remaining kinetic energy of the rotating mechanism is amplified by the planetary gear and drives the internal gear pump; the internal gear pump pumps oil from the low-pressure chamber to the high-pressure chamber, flows through the electric proportional overflow valve to generate a controllable back pressure, forming a damping torque proportional to the square of the pump speed (i.e. vehicle speed).

[0103] In the final stage, the use of hydraulic damping brake can realize low-speed buffering, effectively absorb the last low-speed and large inertia kinetic energy of the system, and completely eliminate the "creeping" and "nodding" phenomena. When the speed drops to 0, the static locking torque is provided by the fully engaged wet multi-plate brake, realizing safe and reliable parking.

[0104] In summary, the embodiment provides a rotating power assembly with multi-stage braking capability, which is equipped with a rotating motor, a wet multi-plate brake, and a hydraulic rotary damper in the system. According to the actual braking demand, motor braking, friction braking (mechanical braking), and hydraulic damping braking can be realized, multiple braking modes can be freely switched, the braking effect can be improved, and the braking impact can be avoided.

[0105] The application connects the power battery with the valve group, when the temperature of the power battery is too low, the motor braking heat, the brake heat and the hydraulic damping heat can be transferred to the power battery through the valve group to accelerate the temperature rise of the battery. To solve the problem of low temperature braking recovery, the application adopts the integration design of hydraulic damping system and wet brake oil circuit, and adds the motor copper loss braking mode, which introduces the heat into the battery cooling system through the cooling circuit, avoids the problem of low temperature energy waste, and improves the energy utilization rate. Through the copper loss braking mode, the effective working range of the system in extremely cold environment is expanded. The application also adopts the planetary gear coaxial driving internal gear pump, the hydraulic damping system and the wet brake oil circuit share the oil source, to avoid the system obesity.

[0106] The application constructs a three-stage braking sequence of "electric braking-friction braking-hydraulic damping" and a braking torque mapping algorithm based on speed feedback to solve the existing engineering machinery damping braking impact problem, fully plays the respective advantages of electric braking (high efficiency, recyclable), friction braking (reliable, large torque), hydraulic braking (smooth, buffering), avoids its shortcomings, realizes function complementation, realizes the whole process smooth braking from high speed to stop through the pre-set braking mode condition and torque gradient switching algorithm, reduces the impact degree by more than 69%, and significantly improves the operation comfort and structural reliability. The application reduces the application of friction braking in the high speed area, reduces the wear and heat load, and prolongs the service life of the brake.

[0107] The application solves the problems of low temperature energy recovery, inconvenient storage of braking recovery energy, braking impact inhibition, and non-inductive switching of braking mode.

[0108] The embodiments of the application are described above in combination with the drawings, but the application is not limited to the above specific embodiments, the above specific embodiments are only illustrative, not limiting, and those skilled in the art can make many forms under the inspiration of the application without departing from the purpose of the application and the scope protected by the claims, which are all within the protection of the application.

Claims

1. A multi-stage braking and slewing power assembly integrating travel and parking functions for engineering machinery, characterized in that, It includes a rotary motor, a wet multi-disc brake, a hydraulic rotary damper, a reducer, a power output shaft, a valve group, an accumulator, a low-pressure electronic pump, and a power battery. The rotary motor is connected to one end of the wet multi-disc brake, the other end of the wet multi-disc brake is connected to one end of the hydraulic rotary damper, the other end of the hydraulic rotary damper is connected to the reducer, and the reducer is connected to the rotary platform via the power output shaft. The oil inlet of the valve group is connected to the hydraulic oil tank via the low-pressure electronic pump, and the oil outlet of the valve group is connected to the accumulator, the wet multi-disc brake, the hydraulic rotary damper, and the power battery, respectively.

2. The rotary power assembly according to claim 1, characterized in that, The wet multi-disc brake includes a spring, multiple sets of dynamic and static friction discs, a hydraulic cylinder, bearings, splines, and a housing; The spline includes external and internal splines. Multiple sets of moving and stationary friction plates include moving friction plates and external friction plates. The external spline is located on the extension of the rotary motor's output shaft, and the internal spline is located in the inner hole of the moving friction plate. The moving friction plate meshes with the external spline on the motor shaft via the internal spline, thus rotating with the motor shaft. The stationary friction plate meshes with the internal spline on the housing via the external spline. The hydraulic cylinder is located in the annular piston cavity within the housing, and the spring is mounted on the piston or pressure plate of the hydraulic cylinder. The bearing is located between the housing and the rotary motor's motor shaft or the hydraulic cylinder's pressure plate. The braking chambers of the hydraulic cylinder and the moving and stationary friction plates are respectively connected to the valve assembly.

3. The rotary power assembly according to claim 1, characterized in that, The hydraulic rotary damper includes a planetary gear, an internal gear pump, and an electro-proportional relief valve. The planetary gear mechanism includes a sun gear, a planet carrier, and a ring gear. The sun gear is connected to the internal gear pump. The planet carrier is fixed to the housing of the rotary power assembly via bearings. The ring gear is connected to the housing of the wet multi-disc brake. The internal gear pump includes a pump shaft, a pinion, and an internal ring gear. The pump shaft is coaxially connected to the sun gear. The pinion is mounted on the pump shaft and rotates at high speed with the pump shaft. The internal ring gear is fixed in the pump body of the internal gear pump and forms an internal meshing relationship with the pinion. The inlet of the electro-proportional relief valve is connected to the outlet of the internal gear pump via a high-pressure oil pipe. The return port of the electro-proportional relief valve is connected to the inlet of the internal gear pump. When the pump shaft is driven, the internal gear pump converts the mechanical energy of rotation into hydraulic energy, drawing in oil from the inlet and discharging pressurized oil from the outlet.

4. The rotary power assembly according to any one of claims 2 or 3, characterized in that, Hydraulic oil in the tank enters the valve assembly via a low-pressure electronic pump. The oil then flows through the valve assembly into the accumulator, the hydraulic cylinder of the wet multi-disc brake, and the braking chamber of the moving and stationary friction pads. The oil supplies power to the hydraulic cylinders, enabling them to brake or release the brakes. It also supplies power to the braking chambers of the moving and stationary friction pads, cooling them during braking. Hot oil flowing out of the accumulator, hydraulic cylinders, and braking chambers of the moving and stationary friction pads returns to the hydraulic tank via the valve assembly. The internal gear pump of the hydraulic rotary damper draws oil from the hydraulic oil tank, and the oil flows into the electro-proportional relief valve to realize hydraulic rotary damping braking. The hot oil flows back to the hydraulic oil tank through the valve group.

5. The rotary power assembly according to claim 4, characterized in that, Hot oil flowing from the accumulator, hydraulic cylinder, and braking chamber of the dynamic and static friction pads flows to the power battery through the valve group. After heating the power battery, the cold oil flows back to the hydraulic oil tank.

6. The rotary power assembly according to claim 1, characterized in that, The slewing powertrain also includes a motor controller, a vehicle controller, and an operating handle. The operating handle is electrically connected to one end of the vehicle controller, and the other end of the vehicle controller is connected to the slewing motor through the motor controller.

7. A control method for a multi-stage braking and slewing power assembly integrating travel and parking functions in engineering machinery, characterized in that, For controlling the integrated multi-stage braking and slewing power assembly for engineering machinery as described in claim 1, comprising: The control commands output by the control handle are obtained through the vehicle controller; In response to control commands, the system acquires the temperature of the slewing battery, the remaining charge of the slewing battery, and the speed of the slewing motor in real time. Based on preset braking mode conditions, it selects the braking mode of the slewing powertrain and controls the slewing motor, wet multi-disc brake, or hydraulic rotary damper to perform braking operations according to the braking mode. The braking modes include motor braking, friction braking, and hydraulic damping braking. When switching braking modes, the output torque of the braking source is calculated by using a braking torque mapping algorithm based on speed feedback, and the braking source is switched according to the output torque.

8. The control method according to claim 7, characterized in that, The motor braking includes normal temperature mode I, normal temperature mode II, and low temperature mode; The vehicle controller compares the current battery temperature T with the first temperature threshold T1 and the current battery charge SOC with the first charge threshold S1. If T > T1 and SOC < S1, it enters normal temperature mode I; if T > T1 and SOC > S1, it enters normal temperature mode II; if T ≤ T1, it enters low temperature mode. The normal temperature mode I uses regenerative braking; the normal temperature mode II uses copper loss braking. When T> the second temperature threshold T2, copper loss braking and electric braking are stopped; in the low temperature mode, it automatically switches to copper loss braking, and converts kinetic energy into heat energy dissipation by controlling the short circuit of the three-phase windings of the motor or connecting a power resistor.

9. The control method according to claim 7, characterized in that, In motor braking mode, when the speed of the rotary motor drops to a preset first speed threshold, the braking mode switching program is started to switch the braking mode from motor braking to friction braking. The output torque of the rotary motor used for motor braking and the wet multi-disc brake used for friction braking are calculated using a braking torque mapping algorithm based on speed feedback. The formula for calculating the output torque of a rotary motor used for motor braking is as follows: T_motor_cmd(n) = T_motor_max * [ (n_current - n_low) / Δn ]; Where T_motor_cmd(n) represents the rotary motor torque as a function of the motor speed n, T_motor_max represents the current command torque of the rotary motor, n_current represents the current rotary motor speed, n_low represents the lower limit speed of the switching interval from motor braking to friction braking, and Δn represents the switching interval from motor braking to friction braking. The formula for calculating the output torque of a wet multi-disc brake used for friction braking is as follows: P_brake_cmd(n) = P_brake_max * [ 1 - (n_current - n_low) / Δn ) ]; Where P_brake_cmd(n) represents the torque of the wet multi-plate brake as a function of the motor speed n, and P_brake_max represents the maximum friction braking torque; When n_current <= n_low, the motor braking torque drops to 0, the friction braking pressure rises to P_brake_max, and the rotary powertrain fully enters the friction braking mode.

10. The control method according to claim 7, characterized in that, When the rotary motor speed drops to the second speed threshold, the hydraulic damping brake is activated. The remaining kinetic energy of the rotary mechanism is amplified by the planetary gears and drives the internal gear pump. The internal gear pump pumps oil from the low-pressure chamber to the high-pressure chamber, and the oil flows through the electro-proportional relief valve to generate controllable back pressure, forming a damping torque proportional to the square of the pump speed. When the motor speed is equal to 0 r / min, the hydraulic damping brake is released, and the friction brake is maintained to achieve parking.

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