WO2022193998A1 - 电机泵、液压***、机械设备 - Google Patents

电机泵、液压***、机械设备 Download PDF

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Publication number
WO2022193998A1
WO2022193998A1 PCT/CN2022/079894 CN2022079894W WO2022193998A1 WO 2022193998 A1 WO2022193998 A1 WO 2022193998A1 CN 2022079894 W CN2022079894 W CN 2022079894W WO 2022193998 A1 WO2022193998 A1 WO 2022193998A1
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WIPO (PCT)
Prior art keywords
motor
pump
variable
speed
control unit
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PCT/CN2022/079894
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English (en)
French (fr)
Inventor
刘子凡
王墨林
贝尼尔施克K
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博世力士乐（北京）液压有限公司
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Publication of WO2022193998A1 publication Critical patent/WO2022193998A1/zh

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/08—Arrangements for controlling the speed or torque of a single motor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity

Definitions

  • the present application relates to a motor pump for a hydraulic system comprising a combination of a variable speed motor and a variable displacement pump.
  • the present application also relates to hydraulic systems employing such motor pumps, especially in off-highway vehicles such as excavators.
  • the motor pump of the hydraulic system of the off-highway vehicle usually adopts a combination of a fixed-speed motor (that is, a scheme of simulating a diesel engine, and the diesel engine is fixed to work at a certain speed) and a variable pump, or a combination of a variable-speed motor and a quantitative pump.
  • a fixed-speed motor that is, a scheme of simulating a diesel engine, and the diesel engine is fixed to work at a certain speed
  • a variable pump or a combination of a variable-speed motor and a quantitative pump.
  • the operation control of the motor pump is usually a scheme that simulates a diesel engine-driven hydraulic pump, which leads to limitations in the performance of the hydraulic system.
  • the response time of the motor pump in the prior art is sometimes not ideal.
  • An object of the present application is to provide an improved electric motor pump for use in a hydraulic system, which can provide optimized performance indicators while reducing energy consumption and dynamic response time.
  • a motor pump comprising:
  • a variable speed motor having a motor controller and a motor shaft
  • a control unit which is configured to:
  • an optimization operation is performed, which takes the total motor pump efficiency and/or the motor pump response time as the optimization goal, and the motor speed and the variable pump displacement as the optimization variables to obtain the optimized Motor speed and variable pump displacement;
  • the rotational speed of the variable speed motor is controlled to be the optimal motor rotational speed
  • the displacement of the variable displacement pump is controlled to be the optimal displacement of the variable displacement pump
  • the overall efficiency of the motor pump and the response time of the motor pump are used as optimization objectives, and the two optimization objectives are assigned respective weight values, which may be changed according to specific work requirements.
  • control unit is provided with at least the following control modes:
  • control unit is further provided with a temperature control mode, wherein, within a preset motor temperature range and/or an ambient temperature range, the control unit controls the motor pump to discharge at the optimized motor speed and variable pump discharge. When the motor temperature range and/or the ambient temperature range is exceeded, the control unit keeps the variable speed motor running at a speed below the set speed limit.
  • a noise control mode is also provided in the control unit, wherein the control unit determines a maximum rotational speed based on the highest allowable motor pump noise and keeps the variable speed motor running at a rotational speed below this maximum rotational speed.
  • control unit is configured to switch between the various control modes based on an operator's input command, and or the control unit automatically switches between the various control modes based on changes in operating conditions.
  • the motor temperature range and/or the ambient temperature range, and/or the maximum allowable motor pump noise are used as constraints in optimal operation.
  • the number of the variable displacement pumps is two or more, both of which are driven by the motor shaft.
  • the application provides, in another aspect thereof, a hydraulic system comprising:
  • an input element configured to be adapted to be manipulated by an operator to input operating instructions to the control unit, the operating instructions indicating at least an updated flow demand
  • control unit controls the operation of the motor pump based on the operation instruction and the current working state of the motor pump.
  • the present application in another aspect thereof, provides a mechanical device, especially an off-highway device, comprising a hydraulic system as described above or an electric motor pump as described above.
  • the mechanical equipment is an excavator, especially a small excavator, wherein the number of variable displacement pumps in the motor pump is two, and the two variable displacement pumps are both driven by the motor shaft, One of the variable displacement pumps is used to drive the excavator's boom, and the other variable displacement pump is used to drive the excavator's arm and bucket.
  • the motor pump includes a combination of a variable speed motor and a variable displacement pump, thereby improving the efficiency of the hydraulic system and shortening the dynamic response time by optimizing the working parameters.
  • FIG. 1 is a hydraulic circuit diagram of a hydraulic system according to a possible embodiment of the present application, and the hydraulic system includes a motor pump according to a possible embodiment of the present application;
  • FIG. 2 is a logic diagram of a motor pump control according to a possible embodiment of the present application.
  • the present application generally relates to a motor pump that incorporates a variable speed motor in combination with a variable displacement pump.
  • the motor pump is suitable for use in hydraulic systems of mechanical equipment (such as off-highway vehicles) to provide hydraulic power to the actuators of the mechanical equipment.
  • FIG. 1 schematically shows a part of a hydraulic system according to a possible embodiment of the present application, which includes the electric motor pump of the present application.
  • the motor pump comprises a variable speed motor 1 with a motor controller 2, eg a control circuit, a frequency converter or the like.
  • the common motor shaft 3 of the motor 1 drives one or more variable displacement pumps - in the example of FIG.
  • the variable displacement pump has an adjustable displacement (amount of hydraulic oil discharged per revolution).
  • For the infinitely variable pump its displacement is infinitely adjustable (that is, it can be continuously changed); for the multi-speed variable pump, its displacement can be changed between each gear (the displacement of each gear amount is fixed).
  • the hydraulic system also includes hydraulic control elements and actuators (not shown in the figures) arranged in the output circuits of the variable displacement pumps 4 , 5 .
  • pressure sensors 6 and 7 are respectively arranged in the output circuits of the variable displacement pumps 4 and 5 for measuring the pressure in the output circuits.
  • the hydraulic system also includes a control unit 8 , which is connected to the input element 9 and capable of receiving operating instructions input by the operator via the input element 9 .
  • the input element 9 may be an operation handle, an operation panel, a remote control, or the like.
  • the control unit 8 is also connected to the pressure sensors 6, 7 and can receive detected pressure signals from them.
  • the control unit 8 is also connected to the motor controller 2, and can control the operation of the motor 1 through the motor controller 2, including adjusting the speed of the motor shaft 3 of the motor 1, and obtaining the working parameters of the motor 1, including the speed and the like.
  • the control unit 8 is also connected to the drives (not shown) of the variable displacement pumps 4 and 5 for controlling the respective displacements of the variable displacement pumps 4 and 5 .
  • the control unit 8 is also connected to hydraulic control elements and controls the state of these hydraulic control elements to achieve the desired action of the actuators.
  • a typical application of the hydraulic system in Figure 1 is in an excavator (especially a small excavator), where the motor 1 is powered by the power battery of the excavator, and the variable pump 4 is used to control the action of the boom of the hydraulic machine. 5 It is used to control the movements of the forearm and bucket of the hydraulic press.
  • the cockpit of an excavator is typically rotatable 360 degrees about a vertical axis.
  • the cabin can be equipped with a separate drive motor or motor pump to drive it to rotate; or, if the motor 1 is large enough, it can also be considered to use the motor 1 to drive an additional pump to drive the cabin to rotate.
  • the driving force of the excavator (especially the small excavator) itself can also be provided by the power battery to completely eliminate the diesel engine.
  • the hydraulic system of Figure 1 may also be used in other types of machinery, including other off-highway vehicles.
  • the common drive shaft 3 of the motor 1 can drive at least one variable displacement pump, and the number of variable displacement pumps depends on the specific action requirements.
  • the control unit 8 controls the rotational speed of the motor 1 (that is, the rotational speed of the motor shaft 3 ) through the motor controller 2 , and controls the rotational speed of the motor 1 through the variable displacement pumps 4 and 5 .
  • the driver controls the respective displacements of the variable displacement pumps 4 and 5 .
  • the control logic within the control unit 8 is used to achieve dynamic control of the motor pump performance to achieve the desired performance optimization.
  • control unit 8 is configured to be able to comprehensively optimize the battery energy consumption and the response time of the motor pump.
  • FIG. 2 an exemplary control logic that the control unit 8 can execute is shown in FIG. 2 , which is described below in conjunction with FIG. 2 .
  • control unit 8 determines the overall efficiency of the motor pump, as described below.
  • the control unit 8 determines the operation command input by the operator through the input element 9 .
  • the operating instructions include the flow demand (Flow Demand) for the variable displacement pumps 4,5.
  • the gear in which the handle-type input element 9 is located corresponds to the corresponding flow requirement.
  • the flow requirements of each variable pump depend on the action to be performed by the corresponding actuator in the mechanical equipment.
  • the flow requirement of each variable pump is the product of the motor speed (revolutions per minute) and the displacement of the variable pump (the amount of hydraulic oil discharged per revolution, usually expressed as a percentage of the maximum displacement).
  • the control unit 8 determines a motor speed estimate n and a displacement estimate V of the variable displacement pumps 4 , 5 based on this flow demand. In addition, the control unit 8 also acquires the current output pressure P_act of the variable displacement pumps 4 and 5 from the pressure sensors 6 and 7 .
  • the control unit 8 determines the variable pump efficiency, including the volumetric efficiency and the hydro-mechanical efficiency, based on the displacement estimates V of the variable pumps 4, 5 and the current output pressure P_act.
  • the variable pump efficiency is determined through a variable pump efficiency look-up table Map1.
  • the look-up table Map1 contains a plurality of efficiency curves for each variable pump, and the curves in each curve represent the pump efficiency corresponding to the pump displacement and the output pressure at the corresponding rotational speed (ie, the motor rotational speed).
  • control unit 8 calculates a motor torque estimation value T (T Calculation) based on the displacement estimation value V of the variable displacement pumps 4, 5, the current output pressure P_act, and the efficiency.
  • the motor torque estimate T can be determined through empirical formulas or table look-up.
  • the control unit 8 determines the motor efficiency based on the motor torque estimate value T and the motor rotation speed estimate value n.
  • the motor efficiency is determined through a motor efficiency look-up table Map2.
  • the look-up table Map2 contains a graph of the motor efficiency, wherein the curve represents the motor efficiency corresponding to the motor torque and rotational speed.
  • control unit 8 determines the motor pump total efficiency E_total (E Calculation) based on the motor efficiency and the variable pump efficiency.
  • the overall motor pump efficiency can be determined as a function of the motor efficiency and the efficiency of each variable pump.
  • control unit 8 determines the motor pump response time, as described below.
  • the motor pump response time is the time required for the variable displacement pumps 4 , 5 of the motor pump to change from the current displacement to the flow demand input by the operator via the input element 9 .
  • control unit 8 acquires the current rotational speed n_act of the motor 1 (eg from the motor controller 2 ) and the current displacement V_act of the variable displacement pumps 4 and 5 (eg from the controller or displacement sensor of the variable displacement pumps 4 and 5 ).
  • control unit 8 determines the motor shaft response time t_shaft based on the current output pressure P_act and the current displacement V_act of the variable displacement pumps 4, 5, the current speed n_act of the motor 1, the displacement estimation value V of the variable displacement pumps 4, 5, and the motor speed estimation value n .
  • the motor shaft response time t_shaft can be determined by empirical formula or table lookup.
  • the control unit 8 determines the respective response times t_1 and t_2 of the variable displacement pumps 4 and 5 based on the pump response time look-up table (Curves).
  • the pump response time look-up table includes two graphs, which are the response time graph for increased displacement (from 0% displacement to 100% displacement) and the response time curve for reduced displacement (from 100% displacement to 0% displacement). quantity) response time curve. Each response time graph plots the response time required to complete a change in displacement at different pump output pressures.
  • control unit 8 selects the largest one among the response time t_shaft of the motor shaft and the respective response times t_1 and t_2 of the variable displacement pumps 4 and 5 as the response time t_max of the motor pump.
  • control unit 8 After determining the motor-pump total efficiency E_total and the motor-pump response time t_max, the control unit 8 takes these two parameters as optimization goals, and uses the motor speed and pump displacement as optimization parameters to optimize (Optimization).
  • optimization objective is expressed as:
  • the optimal motor speed n_opt that reaches the minimum value of [a ⁇ E_total+b ⁇ t_max] and the optimal pump displacements V1_opt and V2_opt of the variable pumps 4 and 5 through an optimization algorithm (eg traversal optimization algorithm, etc.).
  • the optimized motor speed n_opt and the optimized pump displacements V1_opt, V2_opt can be obtained by multiple iterations of the motor speed estimate n and the displacement estimates V of the variable displacement pumps 4 , 5 .
  • control unit 8 controls the rotational speed of the motor 1 to reach n_opt, and controls the displacements of the variable displacement pumps 4 and 5 to reach V1_opt and V2_opt, respectively.
  • the parameters a and b in the optimization objective are adjustable weight values, which are changed according to different application scenarios.
  • different control modes can be set in the control unit 8, and different weighting values a, b can be set in the different control modes.
  • control unit 8 is provided with at least the following control modes:
  • control unit 8 realizes the comprehensive optimization of the efficiency and response time of the motor pump.
  • control unit 8 may be added to the control unit 8 . In this case, only the control logic of the control unit 8 needs to be modified.
  • constraints can be added to the control unit 8 .
  • a temperature constraint can be added to the control unit 8, wherein, within a preset motor temperature range and/or an ambient temperature range, the control unit 8 keeps the motor 1 running with the operating parameters [speed, torque] that can achieve the optimization target.
  • the control unit 8 controls the motor 1 to run at a speed lower than the set speed limit.
  • the motor temperature may be acquired by the control unit 8 from a temperature sensor inside the motor 1
  • the ambient temperature may be acquired by the control unit 8 from the ambient temperature sensor.
  • a noise constraint may be added to the control unit 8, wherein the control unit 8 determines the maximum speed of rotation by the highest allowable noise (the highest of the motor noise and the pump noise), and the control unit 8 keeps the motor 1 below this maximum speed value rotation speed.
  • control modes corresponding to these constraints may be added to the control unit 8 .
  • a temperature control mode may be added to the control unit 8 . After entering the temperature control mode, within the preset motor temperature range and/or ambient temperature range, the control unit 8 keeps the motor 1 running with the working parameters [speed, torque] that can achieve the highest efficiency. When the motor temperature range and/or the ambient temperature range is exceeded, the control unit 8 keeps the motor 1 running at a speed below the set speed limit.
  • a noise control mode may be added to the control unit 8, wherein the control unit 8 keeps the motor 1 running at a rotational speed lower than a certain rotational speed maximum value.
  • the operator can control the control unit 8 to switch between various control modes, eg via the input element 9 .
  • the control unit 8 may automatically switch between various control modes based on changes in operating conditions (eg, based on the input of the input element 9, detection signals of various detection elements, etc.).
  • variable displacement pumps 4 and 5 the pump in the motor pump is described as including the variable displacement pumps 4 and 5; however, those skilled in the art can It is understood that, based on the specific application, the number of variable displacement pumps in the motor pump may be determined, for example including only one variable displacement pump, or three or more variable displacement pumps, which are driven by a common variable speed motor. For the solution of using the same variable speed motor to drive more than two variable displacement pumps, the advantages of the present application over the prior art are more obvious.
  • the optimization objectives in the optimization scheme executed in the control unit 8 described above are the two parameters of the total efficiency of the motor pump and the response time of the motor pump; however, those skilled in the art can understand that, based on specific applications, it is possible to Only one of these two parameters is selected as the optimization objective. In this case, a step in the control logic of the control unit 8 related to another parameter can be omitted. After reading the foregoing description, those skilled in the art can easily conceive a control logic that takes a single parameter as the optimization target.
  • the motor pump in the hydraulic system of the embodiment of the present application includes two variable displacement pumps driven by a common variable speed motor
  • the motor pump in the hydraulic system of the comparative example includes two variable displacement pumps driven by a common fixed speed motor.
  • the data in the table below is the motor speed and battery power consumption under one working condition.
  • the present application further designs a hydraulic system comprising the above-mentioned motor-pump, as well as mechanical equipment employing such a hydraulic system, eg, off-highway equipment, such as excavators (especially small excavators).
  • the mechanical equipment can use a power battery as the main power source, which powers the motor pump and other components in the hydraulic system.
  • the power battery can be used as a power source for driving the off-highway equipment.
  • the motor pump is composed of a variable speed motor and one or more variable displacement pumps, and is combined with a control unit capable of optimizing the performance of the motor pump, which can improve system efficiency and reduce battery energy consumption.
  • control unit can comprehensively optimize different objectives to achieve different performance improvements of the motor pump or hydraulic system or mechanical equipment, which also provides greater flexibility for the design of the motor pump, hydraulic system, and mechanical equipment ( degrees of freedom).

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Analytical Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Mining & Mineral Resources (AREA)
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  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Positive-Displacement Pumps (AREA)

Abstract

一种电机泵包括：变速电机(1)，其具有电机控制器(2)和电机轴(3)；由电机轴驱动的至少一个变量泵(4，5)；以及控制单元(8)，其获取电机泵的当前工作状态，当前工作状态至少包括变速电机（1）的当前转速、以及变量泵(4，5)的当前排量和输出压力。电机泵获取更新的流量需求；基于更新的流量需求以及电机泵的当前工作状态执行优化操作，该优化操作以电机泵总效率和/或电机泵响应时间为优化目标、以电机转速和变量泵排量为优化变量，获得优化的电机转速和变量泵排量；以及控制变速电机（1）的转速变为优化的电机转速，以及控制变量泵（4，5）的排量变为优化的变量泵排量。该电机泵可以提高工作效率、缩短响应时间。

Description

电机泵、液压***、机械设备 技术领域
本申请涉及一种用于液压***的电机泵，其包含变速电机与变量泵的组合。本申请还涉及采用这种电机泵的液压***，尤其是非公路车辆、例如挖掘机中的液压***。
背景技术
在诸如挖掘机等的非公路车辆的液压***中，一种趋势是使用电机泵向执行元件提供液压动力，以取代传统的以柴油机作为动力源的方式。目前，非公路车辆的液压***的电机泵通常采用固定转速的电机(即模拟柴油机的方案，将柴油机固定在某一转速下工作)与变量泵的组合，或是变速电机与定量泵的组合。这常会导致高能耗进而增加电池设计成本。并且，电机泵的操作控制通常是模拟柴油机驱动的液压泵的方案，这导致液压***的性能存在局限性。此外，现有技术中电机泵的响应时间有时不理想。
因此，希望对非公路车辆的液压***中使用的电机泵的配置方式和控制方案作出改进。
发明内容
本申请的一个目的是提供一种改进的用于液压***中的电机泵，其能够提供优化的性能指标，同时降低能耗和动态响应时间。
为此，本申请在其一个方面提供了一种电机泵，其包括：
变速电机，其具有电机控制器和电机轴；
由电机轴驱动的至少一个变量泵；以及
控制单元，其配置成：
获取电机泵的当前工作状态，所述当前工作状态至少包括变速电机的当前转速、以及变量泵的当前排量和输出压力；
获取对电机泵的更新的流量需求；
基于更新的流量需求以及电机泵的当前工作状态执行优化操作，该优化操作以电机泵总效率和/或电机泵响应时间为优化目标、以电机转速和变 量泵排量为优化变量，获得优化的电机转速和变量泵排量；以及
控制变速电机的转速变为优化的电机转速，以及控制变量泵的排量变为优化的变量泵排量。
在一种实施方式中，以电机泵总效率和电机泵响应时间为优化目标，这两个优化目标被赋予各自的权重值，所述权重值可针对具体的工作要求而改变。
在一种实施方式中，控制单元中至少设置有下述控制模式：
标准模式，其中两个权重值是根据电机泵的预期用途而预设的；
效率优先模式，其中电机泵总效率的权重值大于电机泵响应时间的权重值；
动态模式，其中电机泵反应速度的权重值大于电机泵总效率的权重值。
在一种实施方式中，控制单元中还设置有温度控制模式，其中，在预设的电机温度范围和/或环境温度范围内，控制单元控制电机泵以所述优化的电机转速和变量泵排量运转，在超出了电机温度范围和/或环境温度范围时，控制单元保持变速电机以低于设定的转速限值的转速运转。
在一种实施方式中，控制单元中还设置有噪音控制模式，其中，控制单元基于最高允许电机泵噪音确定转速最大值，并且保持变速电机以低于该转速最大值的转速运转。
在一种实施方式中，控制单元配置成基于操作人员的输入指令而在各控制模式之间切换，和或控制单元基于工况的变化而自动实现各种控制模式之间的切换。
在一种实施方式中，电机温度范围和/或环境温度范围，和/或最高允许电机泵噪音，作为优化操作中的约束条件。
在一种实施方式中，所述变量泵的数量为两个或更多个，这两个变量泵均由所述电机轴驱动。
本申请在其另一个方面提供了一种液压***，其包括：
如前所述的电机泵；
布置在所述电机泵的变量泵输出回路中的执行元件和控制元件；以及
输入元件，所述输入元件配置成适于***作人员操控而向所述控制单元输入操作指令，所述操作指令至少指示更新的流量需求；
其中，所述控制单元基于所述操作指令以及电机泵的当前工作状态控制电机泵的操作。
本申请在其另一个方面提供了一种机械设备，尤其是非公路设备，包括如前所述的液压***或如前所述的电机泵。
在一种实施方式中，所述机械设备为挖掘机，尤其是小型挖掘机，其中，所述电机泵中的变量泵的数量为两个，这两个变量泵均由所述电机轴驱动，其中一个变量泵用于驱动挖掘机的大臂，另一个变量泵用于驱动挖掘机的小臂和挖斗。
根据本申请，电机泵中包含变速电机与变量泵的组合，通过优化工作参数从而提高液压***的效率并且缩短动态响应时间。
此外，通过优化工作参数，还可能实现液压***最佳的工作性能，拓宽液压***的操作控制、结构设计上的灵活性。
附图说明
本申请的前述和其它方面将通过下面参照附图所作的详细介绍而被更完整地理解，在附图中：
图1是根据本申请的一种可行实施方式的液压***的液路图，该液压***中包含根据本申请的一种可行实施方式的电机泵；
图2是根据本申请的一种可行实施方式的电机泵控制逻辑图。
具体实施方式
本申请总体上涉及一种电机泵，其包含了变速电机与变量泵的组合。该电机泵适用于机械设备(例如非公路车辆)的液压***中，用以向机械设备的执行元件提供液压动力。
图1示意性展示了根据本申请的一种可行实施方式的液压***的一个局部，其中包含本申请的电机泵。该电机泵包括变速电机1，其具有电机控制器2，例如控制电路、变频器等。电机1的公共电机轴3驱动一个或多个变量泵-在图1的例子中，变量泵包括双向变量泵4和单向变量泵5。变量泵具有可调的排量(每转一圈排出的液压油量)。对于无级变量泵来说，其排量是无级可调的(即，是可以连续变化的)；对于多挡变量泵来说，其 排量可以在各挡之间变化(每挡的排量是固定的)。
液压***还包括布置在变量泵4、5的输出回路中的液压控制元件和执行元件(图中未示出)。此外，变量泵4、5的输出回路中分别布置着压力传感器6、7，用于测量输出回路中的压力。液压***还包括控制单元8，其连接着输入元件9，并且能够接收操作人员由输入元件9输入的操作指令。输入元件9可以是操作柄、操作面板、遥控器等。控制单元8还连接着压力传感器6、7，并且能够接收来自它们的检测压力信号。控制单元8还连接着电机控制器2，并且能够通过电机控制器2控制电机1的运转，包括调节电机1的电机轴3的转速，以及获取电机1的工作参数，包括转速等。控制单元8还连接着变量泵4、5的驱动器(未示出)，用于控制变量泵4、5各自的排量。控制单元8还连接着液压控制元件并且控制这些液压控制元件的状态，以实现执行元件期望的动作。
图1中的液压***的一种典型应用是在挖掘机(尤其是小型挖掘机)中，其中电机1由挖掘机的动力电池供电，变量泵4用于控制液压机的大臂的动作，变量泵5用于控制液压机的小臂和挖斗的动作。此外，挖掘机的座舱通常是可绕竖直轴线转动360度的。为此，可以为座舱配备单独的驱动电机或电机泵来驱动其转动；或者，在电机1足够大的情况下，也可考虑利用电机1带动额外的泵来驱动座舱转动。挖掘机(尤其是小型挖掘机)本身的行驶也可由该动力电池提供驱动力，以完全取消柴油机。
图1中的液压***也可以应用于其它类型的机械设备(包括其它非公路车辆)中。根据具体的应用需求，电机1的公共驱动轴3可以驱动至少一个变量泵，变量泵的数量取决于具体的动作要求。
回到图1，控制单元8在接收到操作人员通过输入元件9输入的操作指令后，通过电机控制器2控制电机1的转速(即电机轴3的转速)，并且通过变量泵4、5的驱动器控制变量泵4、5各自的排量。控制单元8内部的控制逻辑用于实现电机泵性能的动态控制，以实现期望的性能优化。
根据一种可行实施方式，控制单元8配置成能够对电池能耗和电机泵响应时间进行综合优化。为了实现这种综合优化，控制单元8能够执行的一种示例性控制逻辑在图2中展示，下面结合图2描述这种控制逻辑。
一方面，控制单元8确定电机泵总效率，如下所述。
首先，控制单元8通过输入元件9确定操作人员输入的操作指令。操作指令包括对变量泵4、5的流量需求(Flow Demand)。例如，操作柄型的输入元件9所在的挡位对应着相应的流量需求。每个变量泵的流量需求取决于机械设备中的相应执行元件所要进行的动作。并且，每个变量泵的流量需求为电机转速(每分钟转数)与该变量泵的排量(每转一圈排出的液压油量，通常表示为最大排量的百分比)的乘积。
控制单元8基于该流量需求确定电机转速估算值n和变量泵4、5的排量估算值V。此外，控制单元8还从压力传感器6、7获取变量泵4、5当前输出压力P_act。
接下来，控制单元8基于变量泵4、5的排量估算值V和当前输出压力P_act确定变量泵效率，其中包括容积效率和液压-机械效率。根据一种实施方式，变量泵效率通过变量泵效率查表Map1确定。查表Map1中包含针对每个变量泵的多张效率曲线图，每张曲线图中的曲线表示在相应的转速(即电机转速)下对应于泵排量和输出压力的泵效率。
接下来，控制单元8基于变量泵4、5的排量估算值V、当前输出压力P_act和效率计算电机扭矩估算值T(T Calculation)。电机扭矩估算值T可以通过经验公式或查表确定。
接下来，控制单元8基于电机扭矩估算值T和电机转速估算值n确定电机效率。根据一种实施方式，电机效率通过电机效率查表Map2确定。查表Map2中包含电机效率曲线图，其中的曲线表示对应于电机扭矩和转速的电机效率。
接下来，控制单元8基于电机效率和变量泵效率确定电机泵总效率E_total(E Calculation)。电机泵总效率可以由电机效率和各变量泵效率的函数确定。
另一方面，控制单元8确定电机泵响应时间，如下所述。
电机泵响应时间即电机泵的变量泵4、5从当前排量变化到操作人员通过输入元件9输入的流量需求所需的时间。
首先，控制单元8获取电机1当前转速n_act(例如从电机控制器2获取)以及变量泵4、5当前排量V_act(例如从变量泵4、5的控制器或排量传感器获取)。
然后，控制单元8基于变量泵4、5当前输出压力P_act和当前排量V_act、电机1当前转速n_act以及变量泵4、5的排量估算值V、电机转速估算值n确定电机轴响应时间t_shaft。电机轴响应时间t_shaft可以通过经验公式或查表确定。
并且，控制单元8基于泵响应时间查表(Curves)确定变量泵4、5各自的响应时间t_1、t_2。泵响应时间查表包括两张曲线图，分别为排量升高(从0％排量升高到100％排量)响应时间曲线图和排量降低(从100％排量降低到0％排量)响应时间曲线图。每张响应时间曲线图中以曲线表示在不同泵输出压力下完成排量变化所需的响应时间。
然后，控制单元8在电机轴响应时间t_shaft、变量泵4、5各自的响应时间t_1、t_2中选取最大者，作为电机泵响应时间t_max。
在确定了电机泵总效率E_total和电机泵响应时间t_max后，控制单元8以这两个参数为优化目标、以电机转速和泵排量为优化参数进行优化(Optimization)。
例如，优化目标表示为：
min[a×E_total+b×t_max]
通过优化算法(例如遍历寻优算法等)确定达到[a×E_total+b×t_max]最小值的优化电机转速n_opt和变量泵4、5各自的优化泵排量V1_opt、V2_opt。例如，通过对电机转速估算值n和变量泵4、5的排量估算值V进行多次迭代，可得到优化电机转速n_opt和优化泵排量V1_opt、V2_opt。
然后，控制单元8控制电机1的转速达到n_opt，控制变量泵4、5的排量分别达到V1_opt、V2_opt。
优化目标中的参数a、b为可调的权重值，根据不同的应用场景而改变。为此，可在控制单元8中设置不同的控制模式，并且在不同的控制模式中设定不同的权重值a、b。
根据一种可行实施方式，控制单元8中至少设置有下述控制模式：
(1)标准模式，其中权重值a、b可由主机厂根据电机泵的预期用途而预设；
(2)效率优先模式，其中电机泵总效率(电池能耗)被优先考虑，a>b，甚至b可设置为0；
(3)动态模式，其中电机泵反应速度被优先考虑，a<b，甚至a可设置为0。
通过上述控制逻辑，控制单元8实现了电机泵的效率和响应时间两个指标上的综合优化。
本领域技术人员可以理解，可以为控制单元8添加其它的优化目标。在这种情况下，只需修改控制单元8的控制逻辑即可。
本领域技术人员还可以理解，可以为控制单元8添加约束条件。例如，控制单元8中可以添加温度约束条件，其中，在预设的电机温度范围和/或环境温度范围内，控制单元8保持电机1以能实现优化目标的工作参数[转速，扭矩]运转。在超出了电机温度范围和/或环境温度范围时，例如温度高于上限或低于下限，控制单元8控制电机1以低于设定的转速限值的转速运转。电机温度可由控制单元8从电机1内部的温度传感器获取，环境温度可由控制单元8从环境温度传感器获取。
又如，控制单元8中可以添加噪音约束条件，其中，控制单元8通过最高允许噪音(电机噪音和泵噪音中的最高者)确定转速最大值，控制单元8保持电机1以低于该转速最大值的转速运转。
根据具体的应用场合，其它约束条件也可以构想出来。
此外，也可以在控制单元8中添加与这些约束条件相应的控制模式。例如，控制单元8中可以添加温度控制模式。在进入温度控制模式后，在预设的电机温度范围和/或环境温度范围内，控制单元8保持电机1以能实现最高效率的工作参数[转速，扭矩]运转。在超出了电机温度范围和/或环境温度范围时，控制单元8保持电机1以低于设定的转速限值的转速运转。
又如，控制单元8中可以添加噪音控制模式，其中，控制单元8保持电机1以低于某个转速最大值的转速运转。
操作人员可以控制控制单元8在各种控制模式之间切换，例如通过输入元件9。或者，控制单元8可以基于工况的变化(例如基于输入元件9的输入、各种检测元件的检测信号等)而自动实现各种控制模式之间的切换。
此外，可以理解，上面参照图1、图2描述本申请的电机泵的构造以及控制单元8的控制逻辑时，电机泵中的泵描述为包括变量泵4和5；然而， 本领域技术人员可以理解，基于具体的应用，可以确定电机泵中的变量泵的数量，例如仅包含一个变量泵，或是包含3个或更多个变量泵，它们由公共的变速电机驱动。对于利用同一个变速电机驱动两个以上的变量泵的方案，本申请相对于现有技术的优势更为明显。
此外，可以理解，上面描述的控制单元8中执行的优化方案中的优化目标为电机泵总效率和电机泵响应时间这两个参数；然而，本领域技术人员可以理解，基于具体的应用，可以仅选取这两个参数其中之一为优化目标。在这种情况下，控制单元8的控制逻辑中与另一参数相关的步骤就可以省略了。本领域技术人员在阅读了前面的描述后，容易构想出以单一参数为优化目标的控制逻辑。
为了验证本申请的效果，申请人在挖掘机上针对本申请的实施例和传统技术的对比例的电池能耗做了比较。本申请的实施例的液压***中的电机泵包括由公共的变速电机驱动的两个变量泵，对比例的液压***中的电机泵包括由公共的固定转速的电机驱动的两个变量泵。下面的表格中的数据为一种工况下的电机转速和电池能耗。
Figure PCTCN2022079894-appb-000001
通过比较可以看到，同现有技术的各种工作方式相比，本申请的电机泵在挖掘机工作中的总能耗都下降了。
本申请进一步设计包含上述电机泵的液压***，以及采用这种液压***的机械设备，例如非公路设备，诸如挖掘机(尤其是小型挖掘机)。该机械设备可以采用动力电池作为主动力源，该动力电池为电机泵以及液压系 统中的其它元件供电。对于非公路设备而言，该动力电池可以作为驱动该非公路设备行驶的动力源。对于以动力电池作为主动力源的机械设备来说，可能有利于避免排放方面受到的限值。
根据本申请，由变速电机与一个或多个变量泵构成电机泵，并且组合有能够对电机泵的性能进行优化的控制单元，可以提高***效率，降低电池能耗。
此外，控制单元能够对不同的目标进行综合优化，以实现电机泵或液压***或机械设备的不同性能的提升，这还为电机泵、液压***、机械设备的设计提供了更大的灵活性(自由度)。
虽然这里参考具体的示例性实施方式描述了本申请，但是本申请的范围并不局限于所示的细节。在不偏离本申请的基本原理的情况下，可针对这些细节做出各种修改。

Claims (11)

  1. 一种电机泵，包括：
    变速电机(1)，其具有电机控制器(2)和电机轴(3)；
    由电机轴驱动的至少一个变量泵(4，5)；以及
    控制单元(8)，其配置成：
    获取电机泵的当前工作状态，所述当前工作状态至少包括变速电机的当前转速、以及变量泵的当前排量和输出压力；
    获取对电机泵的更新的流量需求；
    基于更新的流量需求以及电机泵的当前工作状态执行优化操作，该优化操作以电机泵总效率和/或电机泵响应时间为优化目标、以电机转速和变量泵排量为优化变量，获得优化的电机转速和变量泵排量；以及
    控制变速电机的转速变为优化的电机转速，以及控制变量泵的排量变为优化的变量泵排量。
  2. 如权利要求1所述的电机泵，其中，以电机泵总效率和电机泵响应时间为优化目标，这两个优化目标被赋予各自的权重值，所述权重值可针对具体的工作要求而改变。
  3. 如权利要求2所述的电机泵，其中，控制单元中至少设置有下述控制模式：
    标准模式，其中两个权重值是根据电机泵的预期用途而预设的；
    效率优先模式，其中电机泵总效率的权重值大于电机泵响应时间的权重值；
    动态模式，其中电机泵反应速度的权重值大于电机泵总效率的权重值。
  4. 如权利要求3所述的电机泵，其中，控制单元中还设置有温度控制模式，其中，在预设的电机温度范围和/或环境温度范围内，控制单元控制电机泵以所述优化的电机转速和变量泵排量运转，在超出了电机温度范围和/或环境温度范围时，控制单元保持变速电机以低于设定的转速限值的转速运转。
  5. 如权利要求3或4所述的电机泵，其中，控制单元中还设置有噪音控制模式，其中，控制单元基于最高允许电机泵噪音确定转速最大值，并且保持变速电机以低于该转速最大值的转速运转。
  6. 如权利要求3至5中任一项所述的电机泵，其中，控制单元配置成基于操作人员的输入指令而在各控制模式之间切换，和或控制单元基于工况的变化而自动实现各种控制模式之间的切换。
  7. 如权利要求1至3中任一项所述的电机泵，其中，电机温度范围和/或环境温度范围，和/或最高允许电机泵噪音，作为优化操作中的约束条件。
  8. 如权利要求1至7中任一项所述的电机泵，其中，所述变量泵的数量为两个或更多个，这两个变量泵均由所述电机轴驱动。
  9. 一种液压***，包括：
    如权利要求1至8中任一项所述的电机泵；
    布置在所述电机泵的变量泵输出回路中的执行元件和控制元件；以及
    输入元件(9)，所述输入元件配置成适于***作人员操控而向所述控制单元输入操作指令，所述操作指令至少指示更新的流量需求；
    其中，所述控制单元基于所述操作指令以及电机泵的当前工作状态控制电机泵的操作。
  10. 一种机械设备，尤其是非公路设备，包括如权利要求9所述的液压***。
  11. 如权利要求10所述的机械设备，其中，所述机械设备为挖掘机，尤其是小型挖掘机，其中，所述电机泵中的变量泵的数量为两个，这两个变量泵均由所述电机轴驱动，其中一个变量泵用于驱动挖掘机的大臂，另一个变量泵用于驱动挖掘机的小臂和挖斗。
PCT/CN2022/079894 2021-03-19 2022-03-09 电机泵、液压***、机械设备 WO2022193998A1 (zh)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5486106A (en) * 1993-10-18 1996-01-23 Hehl; Karl Hydraulic device for supplying a hydraulic driving unit
CN101993006A (zh) * 2010-10-12 2011-03-30 三一汽车起重机械有限公司 汽车起重机及其节能控制方法、节能控制***
CN102493953A (zh) * 2012-01-05 2012-06-13 三一汽车起重机械有限公司 节能控制***、汽车起重机和节能控制方法
CN203516044U (zh) * 2013-10-14 2014-04-02 湖南长昊机械有限公司 一种混凝土臂架泵的控制装置
CN109372832A (zh) * 2018-12-21 2019-02-22 合肥工业大学 一种工况变化下的双变量液压***能耗优化方法
WO2020204803A1 (en) * 2019-04-05 2020-10-08 Epiroc Rock Drills Aktiebolag System and method for controlling operation of a hydraulic system of a mining machine

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5486106A (en) * 1993-10-18 1996-01-23 Hehl; Karl Hydraulic device for supplying a hydraulic driving unit
CN101993006A (zh) * 2010-10-12 2011-03-30 三一汽车起重机械有限公司 汽车起重机及其节能控制方法、节能控制***
CN102493953A (zh) * 2012-01-05 2012-06-13 三一汽车起重机械有限公司 节能控制***、汽车起重机和节能控制方法
CN203516044U (zh) * 2013-10-14 2014-04-02 湖南长昊机械有限公司 一种混凝土臂架泵的控制装置
CN109372832A (zh) * 2018-12-21 2019-02-22 合肥工业大学 一种工况变化下的双变量液压***能耗优化方法
WO2020204803A1 (en) * 2019-04-05 2020-10-08 Epiroc Rock Drills Aktiebolag System and method for controlling operation of a hydraulic system of a mining machine

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