CN115042638A - Method and device for controlling service braking of electric forklift - Google Patents
Method and device for controlling service braking of electric forklift Download PDFInfo
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- CN115042638A CN115042638A CN202210779493.8A CN202210779493A CN115042638A CN 115042638 A CN115042638 A CN 115042638A CN 202210779493 A CN202210779493 A CN 202210779493A CN 115042638 A CN115042638 A CN 115042638A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
- B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/58—Combined or convertible systems
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/423—Torque
Abstract
The application relates to the technical field of forklift braking, and discloses a control method and a control device for service braking of an electric forklift, which comprise the following steps: when the current service braking stage is determined to be the electro-hydraulic composite braking stage, the motor braking torque related to the pedal angle at present is controlled not to exceed the preset maximum value of the braking torque, so that the phenomenon that the motor braking torque rapidly rises along with the reduction of the vehicle speed in the braking process, and sudden braking occurs due to inertia generated by overlarge braking torque when the vehicle speed is close to zero is avoided. In addition, when pure electric braking phase, select the motor braking moment of torsion that is correlated with the footboard angle and the motor braking moment of torsion that is correlated with motor speed less one as the current braking moment of torsion of motor to motor braking moment of torsion reduces along with the speed of a motor is mild, avoids braking moment of torsion to reduce to zero hour transmission shaft energy sudden release and leads to fork truck to take place the shake, guarantees vehicle system safety and controls smoothly from this, and then promotes user experience and feels, realizes simultaneously that a large amount of recoveries of kinetic energy.
Description
Technical Field
The application relates to the technical field of forklift braking, in particular to a method and a device for controlling service braking of an electric forklift.
Background
Electric engineering machinery gradually moves to the market, wherein, electric fork-lift truck when service brake, a large amount of kinetic energy convert the heat and waste through friction braking, and in addition, the heat of conversion leads to the hydraulic oil temperature to rise, need consume extra energy this moment and come to dispel the heat to hydraulic oil. Therefore, the electric forklift recovers energy during service braking, the energy utilization rate of the power battery can be improved, and the operation duration after the power battery is fully charged is prolonged.
At present, an electric forklift usually adopts a double-pedal mode that an accelerating pedal and a braking pedal are independent to realize service braking, and adopts a motor and hydraulic combined braking to realize energy recovery. The angle sensor is installed on the brake pedal, pure motors are used for braking within a certain angle, and motors and hydraulic combined braking are used within a certain angle, for example, pure motors are used for braking within the angle range of 0-40%, and motors and hydraulic combined braking are used within the angle range of 60-100%.
At pure electric braking stage, the braking torque of motor output is proportional with brake pedal angle, and fork truck utilizes the motor to brake when moving forward, and the negative torque of motor output when motor speed is 0, if when still exporting the negative torque, can lead to the motor direction to accelerate, and fork truck accelerates to reverse this moment, appears danger easily. Therefore, normally, when the vehicle speed approaches 0, that is, the motor rotation speed approaches 0, the motor braking torque is cleared. Specifically, when the motor speed is N, the motor braking torque-T is proportional to the brake pedal angle. When the rotating speed of the motor is greater than-N and less than N, the braking torque of the motor is 0, namely the motor does not work. When the rotating speed of the motor is less than-N, the braking torque of the motor is T, and it should be noted that, here, the positive and negative of the rotating speed of the motor and the active torque of the motor only represent the direction, that is, the direction of the rotating speed of the motor is opposite to the direction of the braking torque. After the braking torque of the motor is reduced to 0 from T, the capacity of a transmission shaft of the forklift is suddenly released, so that the fluctuation of the rotating speed of the motor is easily caused, and when the fluctuation range exceeds the range from the rotating speed of the motor to N, the braking torque of the motor correspondingly outputs the torque of T or-T, so that the braking torque of the motor continuously fluctuates between-T, T and 0, the electric forklift is further caused to shake, and the user experience is reduced.
Fig. 1 is a characteristic curve diagram of a motor rotation speed and a motor braking torque provided by the present application, in a motor and hydraulic composite braking stage, as shown in fig. 1, a maximum value of the motor braking torque is Tmax, as can be seen from fig. 1, in a service braking process of a forklift truck, when the motor rotation speed is gradually reduced from 100%, the motor braking torque Tpeak is gradually increased, when the rotation speed reaches about 25%, the motor braking torque reaches the maximum value Tmax, until the rotation speed reaches near zero, the motor still provides a large braking torque Tmax, and further, when the vehicle speed approaches zero, the vehicle deceleration is large, and sudden braking occurs due to inertia, so that the braking comfort is poor.
Therefore, how to guarantee that pure electric heavy forklift can recover a large amount of kinetic energy and slowly reduce the speed when driving for braking, the safety of a vehicle system is realized, the control is smooth, the user experience is improved, and the problem to be solved by technical personnel in the field is needed urgently.
Disclosure of Invention
The application aims to provide a control method and device for service braking of an electric forklift, so that a pure electric heavy forklift can recover a large amount of kinetic energy during service braking, and can slow down the speed, and the user experience is improved.
In order to solve the technical problem, the application provides a method for controlling service braking of an electric forklift, which comprises the following steps:
acquiring the current brake pedal angle of the electric forklift;
determining whether a service braking stage corresponding to the current brake pedal angle reaches an electro-hydraulic composite braking stage; the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking;
if so, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and performing the step of determining whether the service braking stage corresponding to the current brake pedal angle reaches the electro-hydraulic composite braking stage;
and if the current brake pedal angle is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so that the electric forklift can reduce the motor braking torque along with the vehicle speed.
Preferably, the controlling that the motor braking torque currently associated with the pedal angle does not exceed a preset braking torque maximum value comprises:
determining a first braking coefficient according to a preset braking distance and a running braking energy recovery rate;
calculating the motor braking torque associated with the pedal angle according to the first braking coefficient and the current brake pedal angle;
when the motor braking torque related to the pedal angle reaches the preset maximum braking torque value, controlling the current motor braking torque related to the pedal angle to be equal to the maximum braking torque value.
Preferably, selecting the smaller of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor speed as the current braking torque of the motor comprises:
determining a second braking coefficient according to the preset braking distance and the running braking energy recovery rate;
acquiring the current motor rotating speed of the electric forklift;
calculating the motor braking torque related to the motor rotating speed according to the second braking coefficient and the current motor rotating speed;
judging whether the motor braking torque related to the motor rotating speed is smaller than the motor braking torque related to the pedal angle or not;
and if the current braking torque is smaller than the preset braking torque, controlling the current braking torque of the motor to be equal to the motor braking torque related to the motor rotating speed.
Preferably, the preset maximum braking torque value is determined according to the service braking energy recovery rate.
In order to solve the technical problem, the present application further provides a control device for service braking of an electric forklift, including:
the acquisition module is used for acquiring the current brake pedal angle of the electric forklift;
the processing module is used for determining whether the service braking stage corresponding to the current brake pedal angle reaches an electro-hydraulic composite braking stage; the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking;
if so, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and performing the step of determining whether the service braking stage corresponding to the current brake pedal angle reaches the electro-hydraulic composite braking stage;
and if the current brake pedal angle is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so that the electric forklift can reduce the motor braking torque along with the vehicle speed.
In order to solve the technical problem, the application further provides a control device for service braking of the electric forklift, which comprises a memory and a control module, wherein the memory is used for storing a computer program;
and the processor is used for realizing the steps of the control method for service braking of the electric forklift when executing the computer program.
The invention provides a method for controlling service braking of an electric forklift, which comprises the following steps: the method comprises the steps of obtaining the current brake pedal angle of the electric forklift, and determining whether the current service braking stage reaches an electro-hydraulic composite braking stage according to the current brake pedal angle, wherein the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking. And if the electro-hydraulic composite braking stage is reached, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and continuing to judge the current service braking stage. And if the electro-hydraulic combined braking stage is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so as to reduce the motor braking torque of the electric forklift along with the vehicle speed. Therefore, according to the technical scheme provided by the application, in the electro-hydraulic composite braking stage, the motor braking torque related to the pedal angle at present is controlled not to exceed the preset maximum braking torque value, so that the situation that the motor braking torque rapidly rises along with the reduction of the vehicle speed in the braking process is avoided, and the sudden braking phenomenon occurs due to inertia generated by overlarge braking torque when the vehicle speed is close to zero. In addition, in pure electric braking phase, select the motor braking moment of torsion that is correlated with the footboard angle and the motor braking moment of torsion that is correlated with motor speed less than as the current braking moment of torsion of motor for motor braking moment of torsion reduces along with the speed of a motor is mild, avoids braking moment of torsion to reduce to zero hour transmission shaft energy sudden release and leads to fork truck to take place the shake, and then promotes user experience and feels.
In addition, the application also provides a control device for the service braking of the electric forklift, which corresponds to the control method for the service braking of the electric forklift and has the same effect as the control method.
Drawings
In order to more clearly illustrate the embodiments of the present application, the drawings needed for the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained by those skilled in the art without inventive effort.
Fig. 1 is a characteristic curve diagram of a motor speed and a motor braking torque provided by the present application;
fig. 2 is a flowchart of a method for controlling service braking of an electric forklift according to an embodiment of the present application;
fig. 3 is a characteristic graph of a motor speed and a motor braking torque according to an embodiment of the present disclosure;
fig. 4 is a structural diagram of a control device for service braking of an electric forklift according to an embodiment of the present application;
fig. 5 is a structural diagram of a control device for service braking of an electric forklift according to another embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without any creative effort belong to the protection scope of the present application.
The core of the application is to provide a control method and a control device for service braking of an electric forklift, and in the electro-hydraulic composite braking stage, the motor braking torque associated with the pedal angle is controlled not to exceed the preset maximum braking torque value, so that the situation that the motor rotating speed of the electric forklift is close to zero is avoided, the deceleration is very large, and the sudden braking phenomenon occurs due to inertia, and the braking comfort is poor. In addition, in the pure electric braking stage, the smaller one of the motor braking torque related to the pedal angle and the motor braking torque related to the motor rotating speed is selected as the current braking torque of the motor, and then the electric forklift is enabled to be stably reduced along with the speed of the motor.
In order that those skilled in the art will better understand the disclosure, the following detailed description will be given with reference to the accompanying drawings.
Electric engineering machinery gradually moves to the market, wherein, electric fork-lift truck when service brake, a large amount of kinetic energy convert the heat and waste through friction braking, and in addition, the heat of conversion leads to the hydraulic oil temperature to rise, need consume extra energy this moment and come to dispel the heat to hydraulic oil. Therefore, the electric forklift recovers energy during service braking, the energy utilization rate of the power battery can be improved, and the operation duration after the power battery is fully charged is prolonged.
At present, an electric forklift usually adopts single-pedal control to realize service braking, a single-pedal control mode is adopted, and after a user steps on an accelerator pedal to accelerate, the accelerator pedal is released to realize service braking and energy recovery. In the process, the speed of accelerator pedal release determines the intensity of service braking and the energy recovery, namely, when the accelerator pedal is released slowly, the braking intensity is low and the energy recovery is low, and when the accelerator pedal is released quickly, the braking intensity is high and the energy recovery is high. It can be understood that need release accelerator pedal fast when more energy is retrieved to needs, and high strength braking can lead to the user to drive because inertia and control the travelling comfort poor, and the mode of single pedal control only is fit for the car body lightly, the less fork truck of tonnage, to the great fork truck of car body weight and tonnage, on the one hand can't guarantee braking distance, on the other hand the security is low when the braking breaks down.
Therefore, at present, for a forklift with a heavy body and a large tonnage, the service braking is usually realized by adopting a double-pedal mode with independent accelerating and braking pedals, and the energy recovery is realized by adopting a motor and hydraulic combined braking. The angle sensor is installed on the brake pedal, pure motors are used for braking within a certain angle, and motors and hydraulic combined braking are used within a certain angle, for example, pure motors are used for braking within the angle range of 0-40%, and motors and hydraulic combined braking are used within the angle range of 60-100%.
At pure electric braking stage, the braking torque of motor output is proportional with brake pedal angle, and fork truck utilizes the motor to brake when moving forward, and the negative torque of motor output when motor speed is zero, if when still exporting the negative torque, can lead to the motor direction to accelerate, and fork truck accelerates to reverse this moment, appears danger easily. Therefore, normally, the motor braking torque is cleared when the vehicle speed is close to zero, that is, the motor rotation speed is close to zero. Specifically, when the motor speed is N0, the motor braking torque-T is proportional to the brake pedal angle, wherein the direction of the motor speed is opposite to the direction of the braking torque. When the motor speed is greater than-N0 and less than N0, the motor braking torque is zero, i.e., the motor is not operated. When the motor speed is less than-N0, the motor braking torque is T. After the braking torque of the motor is reduced to zero from T, the capacity on a transmission shaft of the electric forklift is suddenly released, so that the fluctuation of the rotating speed of the motor is easily caused, and when the fluctuation range exceeds the range from motor-N0 to motor-N0, the braking torque of the motor correspondingly outputs the torque of T or-T, so that the braking torque of the motor continuously fluctuates, the forklift is further caused to shake, and the user experience is reduced.
In the motor and hydraulic combined braking stage, as shown in fig. 1, the maximum value of the motor braking torque is Tmax, as can be seen from fig. 1, in the service braking process of the forklift, when the rotating speed of the motor is gradually reduced from 100%, the motor braking torque Tpeak is gradually increased, when the rotating speed reaches about 25%, the motor braking torque reaches the maximum value Tmax, until the rotating speed reaches near zero, the motor still provides a huge braking torque, and further, the vehicle speed approaches zero, the vehicle deceleration is very large, and the phenomenon of sudden braking occurs due to inertia, so that the braking comfort is poor.
In order to enable the electric forklift to slow down in the whole braking process, improve the energy recovery rate and further improve the user experience, the embodiment of the application provides a control method for the service braking of the electric forklift.
Fig. 2 is a flowchart of a method for controlling service braking of an electric forklift according to an embodiment of the present application, and as shown in fig. 2, the method includes:
s10: and acquiring the current brake pedal angle of the electric forklift.
S11: determining whether a service braking stage corresponding to the current brake pedal angle reaches an electro-hydraulic composite braking stage; the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking, if the service braking stage is reached, the step S12 is carried out, and if the service braking stage is not reached, the step S13 is carried out.
In a specific embodiment, the electric forklift realizes service braking by adopting a double-pedal mode with independent accelerating and braking pedals, and when the electric forklift brakes, the service braking stage of the current forklift can be determined according to the angle of the braking pedal stepped by a user. Therefore, in step S10, the current brake pedal angle of the electric forklift is obtained, and it is determined whether the corresponding service braking stage reaches the electro-hydraulic compound braking stage according to the current brake pedal angle.
It can be understood that the electro-hydraulic compound braking stage is a service braking stage combining motor braking and hydraulic braking, and includes a pure motor braking stage in addition to the electro-hydraulic compound braking stage, and the service braking stage of the electric forklift can be determined according to the angle of the pedal, for example, the service braking stage is determined when the angle is 0-15 degrees, and the service braking stage is determined when the angle is more than 15 degrees. The application is not limited to the angle range corresponding to the pure motor braking stage and the angle range corresponding to the electro-hydraulic composite braking stage.
S12: if so, controlling the brake torque of the motor currently associated with the pedal angle not to exceed the preset maximum brake torque value, and proceeding to step S11.
If when current brake pedal angle reached the compound braking stage of electricity liquid, can confirm that electric fork truck is in the braking stage that motor braking and hydraulic braking combined together, as shown in fig. 1, in braking process, the continuous reduction of vehicle-mounted motor rotational speed, motor braking moment of torsion Tpeak can constantly rise, in order to avoid motor rotational speed to be close 0, motor braking moment of torsion reaches Tmax, and then lead to fork truck when stopping soon because the phenomenon of inertia emergence emergency braking, the goods that appear on the electric fork truck even produces the potential safety hazard because inertia drops, reduce user experience and feel. Therefore, the motor braking torque related to the pedal angle at present is controlled not to exceed the preset maximum braking torque value in the electro-hydraulic compound braking stage.
Fig. 3 is a characteristic curve diagram of the motor rotation speed and the motor braking torque provided in the embodiment of the present application, and as shown in fig. 3, when the motor braking torque Tpeak continuously increases with the decrease of the motor rotation speed, the motor braking torque Tpeak is controlled not to exceed the preset maximum braking torque value Tlimit. In fact, the maximum braking torque value Tlimit is an upper limit for limiting the motor braking torque value Tpeak, and in order to avoid sudden braking of the electric forklift when the motor braking torque value Tpeak reaches Tmax, the motor braking torque value currently associated with the pedal angle is controlled to be equal to the maximum braking torque value Tlimit when the motor braking torque value Tpeak reaches the maximum braking torque value Tlimit. Therefore, the braking torque of the motor cannot rise sharply along with the continuous reduction of the rotating speed of the motor, the phenomenon that sudden braking occurs due to the fact that the braking torque of the motor is too large and the deceleration is too large when the rotating speed of the motor is close to 0 is avoided, the braking comfort is improved, and meanwhile the braking safety is improved.
In fact, during the braking of the vehicle, sometimes the brake pedal is stepped on to brake when an obstacle exists in front of the vehicle, and when the obstacle is cleared, the brake pedal is gradually released to continue the vehicle, and at this time, the current brake pedal angle may gradually decrease to the current corresponding service braking stage, and the vehicle enters the pure electric braking stage, so that the step S12 needs to be executed in real time to determine the service braking stage corresponding to the current brake pedal angle.
S13: and determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so as to reduce the motor braking torque of the electric forklift along with the vehicle speed.
In the implementation, in the pure electric braking stage, in order to avoid that the motor rotation speed is close to zero, the motor braking torque is reset to cause the electric forklift to shake, and therefore, in the embodiment of the application, after the service braking stage corresponding to the current brake pedal angle is determined to be the pure electric braking stage, the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotation speed are respectively obtained, and the smaller motor braking torque is selected as the current braking torque of the motor. In fact, at any time, the rotating speed of the motor is gradually reduced, the motor braking torque related to the rotating speed of the motor is smaller than the motor braking torque related to the pedal angle, at the moment, the braking torque of the motor can be gradually reduced along with the rotating speed of the motor, and the situation that the capacity of the transmission shaft of the electric forklift is suddenly released, and then the rotating speed of the motor is fluctuated is avoided.
It can be understood that when the distance of service braking is larger, the vehicle runs more smoothly, the comfort is good, but the energy recovery rate of the electric forklift is low. If the distance of service braking is larger, the vehicle running inertia is large, the comfort is poor, but the energy recovery rate of the electric forklift is high. Therefore, the braking torque maximum value Tlimit is smaller than Tmax, and needs to be set according to the actual demand of the energy recovery rate when the braking torque maximum value Tlimit is set.
The method for controlling the service braking of the electric forklift comprises the following steps: the method comprises the steps of obtaining the current brake pedal angle of the electric forklift, and determining whether the current service braking stage reaches an electro-hydraulic composite braking stage according to the current brake pedal angle, wherein the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking. And if the electro-hydraulic composite braking stage is reached, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and continuing to judge the current service braking stage. And if the electro-hydraulic combined braking stage is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so as to reduce the motor braking torque of the electric forklift along with the vehicle speed. Therefore, according to the technical scheme provided by the application, in the electro-hydraulic composite braking stage, the motor braking torque related to the pedal angle at present is controlled not to exceed the preset maximum braking torque value, so that the situation that the motor braking torque rapidly rises along with the reduction of the vehicle speed in the braking process is avoided, and the sudden braking phenomenon occurs due to inertia generated by overlarge braking torque when the vehicle speed is close to zero. In addition, in pure electric braking phase, select the motor braking moment of torsion that is correlated with the footboard angle and the motor braking moment of torsion that is correlated with motor speed less than as the current braking moment of torsion of motor for motor braking moment of torsion reduces along with the speed of a motor is mild, avoids braking moment of torsion to reduce to zero hour transmission shaft energy sudden release and leads to fork truck to take place the shake, and then promotes user experience and feels.
In a specific implementation, when the motor braking torque related to the pedal angle does not exceed the preset maximum braking torque value, the motor braking torque related to the pedal angle is determined according to a formula Tp-k 1A, wherein k1 is a first braking coefficient, and A is the current pedal braking angle.
It should be noted that the first braking coefficient k1 is related to the service braking distance and the energy recovery rate of the electric forklift, and therefore, it is necessary to determine the first braking coefficient according to the preset braking distance and the service braking energy recovery rate, and calculate the motor braking torque Tp associated with the pedal angle according to the first braking coefficient k1 and the current brake pedal angle a degree.
When the braking torque Tp of the motor related to the pedal angle reaches the preset maximum braking torque value Tlimit shown in FIG. 3, Tlimit is controlled, and further, the situation that the braking torque Tp exceeds Tlimit along with the reduction of the motor rotating speed, so that the deceleration is too large when the motor rotating speed approaches 0, and the electric forklift has sudden braking limitation due to inertia is avoided.
The method for controlling the service braking of the electric forklift provided by the embodiment of the application determines a first braking coefficient according to a preset braking distance and a service braking energy recovery rate, calculates the motor braking torque associated with a pedal angle according to the first braking coefficient and the current brake pedal angle, and controls the motor braking torque associated with the pedal angle to be equal to the maximum braking torque when the motor braking torque associated with the pedal angle reaches the maximum preset braking torque value, so that the situation that the motor braking torque is continuously increased along with the continuous reduction of the motor rotating speed and the deceleration is also continuously increased in an electro-hydraulic composite braking stage of the electric forklift, and further, when the motor rotating speed is close to 0, the phenomenon of sudden braking occurs due to inertia, the service braking comfort of the electric forklift is improved, and the service braking safety is improved.
On the basis of the above embodiment, if it is determined that the current corresponding service braking phase is the pure electric braking phase according to the current pedal braking angle, in addition to obtaining the motor braking torque associated with the pedal angle, the motor braking torque Ts associated with the motor rotation speed is determined according to a formula Ts k2 × N0, where k2 is the second braking coefficient and N0 is the current motor rotation speed of the electric forklift.
Similarly, a second braking coefficient k2 is determined according to a preset braking distance and a service braking energy recovery rate, and a motor braking torque Ts associated with the motor speed is calculated according to the second braking coefficient k2 and the acquired current motor speed N0 of the electric forklift.
In fact, during braking, when the motor rotation speed reaches a certain value, the motor braking torque Ts associated with the motor rotation speed is necessarily smaller than the motor braking torque Tp associated with the pedal angle, therefore, in the pure electric braking stage, the smaller of Ts and Tp is selected as the current braking torque of the motor, that is, whether the motor braking torque Ts associated with the motor rotation speed is smaller than the motor braking torque Tp associated with the pedal angle is judged, and if so, the current braking torque of the motor is controlled to be equal to the motor braking torque Ts associated with the motor rotation speed. Therefore, the actual braking torque of the motor is gradually reduced along with the continuous reduction of the rotating speed of the motor. The situation that when the rotating speed of the motor is close to 0, the braking torque of the motor is reset suddenly to cause sudden release of the capacity on a transmission shaft of the electric forklift, and the electric forklift is shaken is avoided.
The preset maximum braking torque value Tlimit limits the upper limit of the electric forklift in the electro-hydraulic combined braking stage, and the motor braking torque Ts related to the motor rotation speed is a process of slowly reducing the motor braking torque according to the motor rotation speed N.
According to the method for controlling the service braking of the electric forklift, provided by the embodiment of the application, the second braking coefficient is determined according to the preset braking distance and the service braking energy recovery rate, and the current motor rotating speed of the electric forklift is obtained. And calculating a motor braking torque associated with the motor rotating speed according to the second braking coefficient and the current motor rotating speed, and controlling the current braking torque of the motor to be equal to the motor braking torque associated with the motor rotating speed when the motor braking torque associated with the motor rotating speed is smaller than the motor braking torque associated with the pedal angle. From this, associate electric fork truck's motor braking moment of torsion with motor speed, control motor braking moment of torsion promptly and descend gently along with motor speed, avoid once only with the clear zero hour of motor braking moment of torsion, lead to transmission shaft ability sudden release electric fork truck to take place the shake, and then promote user experience and feel.
In particular, if it is desired to recover a large amount of energy during service braking of an electric forklift, the service braking distance is short, but the comfort is poor due to inertia braking. On the contrary, if the service braking distance is longer, the comfort of the service braking of the vehicle is better, but the energy recovery rate is lower. The maximum braking torque value is related to the service braking energy recovery rate, so that when the maximum braking torque value is set, comprehensive determination needs to be carried out according to the requirement of the actual energy recovery rate and the service braking distance.
According to the control method for the service braking of the electric forklift, the preset maximum braking torque value is determined according to the service braking energy recovery rate, the comfort of service braking is guaranteed, more energy is recovered as far as possible, and the experience of a user in using the electric forklift is further improved.
In the above embodiments, a control method of service braking of an electric forklift is described in detail, and the application also provides an embodiment corresponding to the control device of service braking of an electric forklift. It should be noted that the present application describes the embodiments of the apparatus portion from two perspectives, one is based on the functional module, and the other is based on the hardware structure.
Fig. 4 is a structural diagram of a control device for service braking of an electric forklift according to an embodiment of the present application, and as shown in fig. 4, the device includes:
and the obtaining module 10 is used for obtaining the current brake pedal angle of the electric forklift.
The processing module 11 is configured to determine whether a service braking stage corresponding to a current brake pedal angle reaches an electro-hydraulic combined braking stage; the method comprises the steps of determining whether the current service braking stage corresponding to the angle of a brake pedal is a pure electric braking stage, and selecting the smaller one of the motor braking torque related to the angle of the brake pedal and the motor braking torque related to the rotating speed of the motor as the current braking torque of the motor so that the electric forklift can reduce the motor braking torque along with the speed of the vehicle.
Since the embodiments of the apparatus portion and the method portion correspond to each other, please refer to the description of the embodiments of the method portion for the embodiments of the apparatus portion, which is not repeated here.
The application embodiment provides a controlling means of electric fork-lift service braking, includes: the method comprises the steps of obtaining the current brake pedal angle of the electric forklift, and determining whether the current service braking stage reaches an electro-hydraulic composite braking stage according to the current brake pedal angle, wherein the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking. And if the electro-hydraulic composite braking stage is reached, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and continuing to judge the current service braking stage. And if the electro-hydraulic combined braking stage is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so as to reduce the motor braking torque of the electric forklift along with the vehicle speed. Therefore, according to the technical scheme provided by the application, in the electro-hydraulic composite braking stage, the motor braking torque related to the pedal angle at present is controlled not to exceed the preset maximum braking torque value, so that the situation that the motor braking torque rapidly rises along with the reduction of the vehicle speed in the braking process is avoided, and the sudden braking phenomenon occurs due to inertia generated by overlarge braking torque when the vehicle speed is close to zero. In addition, in pure electric braking phase, select the motor braking moment of torsion that is correlated with the footboard angle and the motor braking moment of torsion that is correlated with motor speed less than as the current braking moment of torsion of motor for motor braking moment of torsion reduces along with the speed of a motor is mild, avoids braking moment of torsion to reduce to zero hour transmission shaft energy sudden release and leads to fork truck to take place the shake, and then promotes user experience and feels.
Fig. 5 is a structural diagram of a control device for service braking of an electric forklift according to another embodiment of the present application, and as shown in fig. 5, the control device for service braking of an electric forklift includes: a memory 20 for storing a computer program;
the processor 21 is configured to implement the steps of the method for controlling service braking of an electric forklift as mentioned in the above embodiments when executing the computer program.
The control device for the service braking of the electric forklift provided by the embodiment can include, but is not limited to, a smart phone, a tablet computer, a notebook computer or a desktop computer.
The processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, and the like. The Processor 21 may be implemented in at least one hardware form of a Digital Signal Processor (DSP), a Field-Programmable Gate Array (FPGA), and a Programmable Logic Array (PLA). The processor 21 may also include a main processor and a coprocessor, where the main processor is a processor for Processing data in an awake state, and is also called a Central Processing Unit (CPU); a coprocessor is a low power processor for processing data in a standby state. In some embodiments, the processor 21 may be integrated with an image processor (GPU), and the GPU is responsible for rendering and drawing the content required to be displayed by the display screen. In some embodiments, the processor 21 may further include an Artificial Intelligence (AI) processor for processing computing operations related to machine learning.
The memory 20 may include one or more computer-readable storage media, which may be non-transitory. Memory 20 may also include high speed random access memory, as well as non-volatile memory, such as one or more magnetic disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used for storing a computer program 201, wherein after being loaded and executed by the processor 21, the computer program can implement the relevant steps of the method for controlling service braking of an electric forklift disclosed in any one of the foregoing embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202, data 203, and the like, and the storage manner may be a transient storage manner or a permanent storage manner. Operating system 202 may include, among others, Windows, Unix, Linux, and the like. The data 203 may include, but is not limited to, relevant data involved in the control method of service braking of the electric fork-lift truck, and the like.
In some embodiments, the control device for service braking of the electric forklift may further include a display 22, an input/output interface 23, a communication interface 24, a power supply 25 and a communication bus 26.
It will be appreciated by those skilled in the art that the arrangement shown in figure 5 does not constitute a limitation of the means for controlling the service brakes of an electric forklift and may include more or fewer components than those shown.
The control device for service braking of the electric forklift provided by the embodiment of the application comprises a memory and a processor, wherein when the processor executes a program stored in the memory, the following method can be realized: a control method for service braking of an electric forklift.
The control device for service braking of the electric forklift provided by the embodiment of the application has the advantages that in the electro-hydraulic composite braking stage, the motor braking torque related to the pedal angle at present is controlled not to exceed the preset maximum braking torque value, the motor braking torque is prevented from rapidly rising along with the reduction of the vehicle speed in the braking process, and the emergency braking phenomenon is caused due to inertia generated by overlarge braking torque when the vehicle speed is close to zero. In addition, in pure electric braking phase, select the motor braking moment of torsion that is correlated with the footboard angle and the motor braking moment of torsion that is correlated with motor speed less than as the current braking moment of torsion of motor for motor braking moment of torsion reduces along with the speed of a motor is mild, avoids braking moment of torsion to reduce to zero hour transmission shaft energy sudden release and leads to fork truck to take place the shake, and then promotes user experience and feels.
The method and the device for controlling the service braking of the electric forklift are described in detail above. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in the process, method, article, or apparatus that comprises the element.
Claims (6)
1. A method for controlling service braking of an electric forklift is characterized by comprising the following steps:
acquiring the current brake pedal angle of the electric forklift;
determining whether a service braking stage corresponding to the current brake pedal angle reaches an electro-hydraulic composite braking stage; the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking;
if so, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and performing the step of determining whether the service braking stage corresponding to the current brake pedal angle reaches the electro-hydraulic composite braking stage;
and if the current brake pedal angle is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so that the electric forklift can reduce the motor braking torque along with the vehicle speed.
2. The method of controlling service braking of an electric fork lift truck as set forth in claim 1, wherein said controlling the motor braking torque currently associated with the pedal angle not to exceed a predetermined maximum braking torque value comprises:
determining a first braking coefficient according to a preset braking distance and a driving braking energy recovery rate;
calculating the motor braking torque associated with the pedal angle according to the first braking coefficient and the current brake pedal angle;
when the motor braking torque related to the pedal angle reaches the preset maximum braking torque value, controlling the current motor braking torque related to the pedal angle to be equal to the maximum braking torque value.
3. The method of controlling service braking of an electric fork lift truck as recited in claim 2, wherein selecting the lesser of said motor braking torque associated with pedal angle and said motor braking torque associated with motor speed as the current braking torque of the motor comprises:
determining a second braking coefficient according to the preset braking distance and the running braking energy recovery rate;
acquiring the current motor rotating speed of the electric forklift;
calculating the motor braking torque related to the motor rotating speed according to the second braking coefficient and the current motor rotating speed;
judging whether the motor braking torque related to the motor rotating speed is smaller than the motor braking torque related to the pedal angle or not;
and if the current braking torque is smaller than the preset braking torque, controlling the current braking torque of the motor to be equal to the motor braking torque related to the motor rotating speed.
4. The method of claim 1, wherein the predetermined maximum braking torque is determined according to a service braking energy recovery rate.
5. The utility model provides a controlling means of electric fork truck service brake which characterized in that includes:
the acquisition module is used for acquiring the current brake pedal angle of the electric forklift;
the processing module is used for determining whether the service braking stage corresponding to the current brake pedal angle reaches an electro-hydraulic composite braking stage; the electro-hydraulic composite braking stage is a service braking stage combining motor braking and hydraulic braking;
if so, controlling the current motor braking torque related to the pedal angle not to exceed the preset maximum braking torque value, and performing the step of determining whether the service braking stage corresponding to the current brake pedal angle reaches the electro-hydraulic composite braking stage;
and if the current brake pedal angle is not reached, determining that the service braking stage corresponding to the current brake pedal angle is a pure electric braking stage, and selecting the smaller one of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor rotating speed as the current braking torque of the motor so that the electric forklift can reduce the motor braking torque along with the vehicle speed.
6. The control device for the service braking of the electric forklift is characterized by comprising a memory, a controller and a controller, wherein the memory is used for storing a computer program;
a processor for implementing the steps of the method of controlling service braking of an electric fork-lift truck according to any one of claims 1 to 4 when executing said computer program.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210779493.8A CN115042638A (en) | 2022-07-04 | 2022-07-04 | Method and device for controlling service braking of electric forklift |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210779493.8A CN115042638A (en) | 2022-07-04 | 2022-07-04 | Method and device for controlling service braking of electric forklift |
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| CN115042638A true CN115042638A (en) | 2022-09-13 |
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| CN202210779493.8A Pending CN115042638A (en) | 2022-07-04 | 2022-07-04 | Method and device for controlling service braking of electric forklift |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117565834A (en) * | 2024-01-16 | 2024-02-20 | 合肥搬易通科技发展有限公司 | Stable parking braking method and system based on proportional service brake |
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2022
- 2022-07-04 CN CN202210779493.8A patent/CN115042638A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117565834A (en) * | 2024-01-16 | 2024-02-20 | 合肥搬易通科技发展有限公司 | Stable parking braking method and system based on proportional service brake |
| CN117565834B (en) * | 2024-01-16 | 2024-03-19 | 合肥搬易通科技发展有限公司 | Stable parking braking method and system based on proportional service brake |
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