A control method and device for the driving brake of an electric forklift

Abstract

The present application relates to the technical field of forklift braking, and discloses a control method and device for electric forklift driving braking, including: when it is determined that the current driving braking stage is the electro-hydraulic composite braking stage, by controlling the motor braking torque associated with the current pedal angle not to exceed the maximum preset braking torque, it is avoided that the motor braking torque rapidly increases as the vehicle speed decreases during braking, and the phenomenon of sudden braking due to excessive braking torque and inertia when the vehicle speed approaches zero. In addition, during the pure electric motor braking stage, the smaller of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor speed is selected as the current motor braking torque, so that the motor braking torque decreases as the vehicle speed slowly decreases, avoiding the sudden release of the drive shaft energy when the braking torque rapidly drops to zero and causing the forklift to shake. Thereby ensuring the safety of the vehicle system and the smoothness of operation, further improving the user experience, and at the same time achieving a large amount of kinetic energy recovery.

Description

Technical Field

[0001] The present application relates to the technical field of forklift braking, and particularly to a control method and device for electric forklift driving braking. Background Art

[0002] Electrified construction machinery is gradually entering the market. Among them, when an electric forklift is driving and braking, a large amount of kinetic energy is wasted by being converted into heat through frictional braking. In addition, the converted heat causes the temperature of the hydraulic oil to rise, and at this time, additional energy needs to be consumed to dissipate the heat of the hydraulic oil. It can be seen that recovering energy during the driving braking of an electric forklift can improve the energy utilization rate of the power battery and extend the operation duration after the power battery is fully charged.

[0003] Currently, electric forklifts usually adopt a dual-pedal method with independent acceleration and braking pedals to achieve driving braking, and adopt motor and hydraulic composite braking to achieve energy recovery. An angle sensor is installed on the braking pedal. Within a certain angle range, pure motor braking is used, and within a certain angle range, motor and hydraulic composite braking is used. For example, within the angle range of 0 - 40%, pure motor braking is used, and within the angle range of 60 - 100%, motor and hydraulic composite braking is used.

[0004] During the pure motor braking stage, the braking torque output by the motor is proportional to the braking pedal angle. When the forklift is moving forward and braking using the motor, the motor outputs a negative torque. When the motor speed is 0, if a negative torque is still output, it will cause the motor to accelerate in the opposite direction, and at this time, the forklift accelerates in reverse, which is prone to danger. Therefore, generally, when the vehicle speed is close to 0, that is, when the motor speed is close to 0, the motor braking torque is cleared. Specifically, when the motor speed is N, the motor braking torque -T is proportional to the braking pedal angle. When the motor speed is greater than -N and less than N, the motor braking torque is 0, that is, the motor does not work. When the motor speed is less than -N, the motor braking torque is T. It should be noted that the positive and negative of the motor speed and the motor driving torque here only represent the direction, that is, the direction of the motor speed is opposite to the direction of the braking torque. Since the motor braking torque suddenly releases the energy on the drive shaft of the forklift after dropping from T to 0, it is easy to cause fluctuations in the motor speed. When the fluctuation range exceeds the range of the motor speed from -N to N, the motor braking torque will correspondingly output a torque of T or -T, causing the motor braking torque to continuously fluctuate between -T, T, and 0, thereby causing the electric forklift to vibrate and reducing the user experience.

[0005] Figure 1 The following is a characteristic curve graph of the motor speed and the motor braking torque provided by the present application. During the motor and hydraulic composite braking stage, as Figure 1 shown, the maximum value of the motor braking torque is Tmax, and from Figure 1It can be known that during the driving braking process of the forklift, when the motor speed gradually decreases from 100%, the motor braking torque Tpeak gradually increases. When the speed reaches about 25%, the motor braking torque reaches the maximum value Tmax. Until the speed drops to near zero, the motor still provides a huge braking torque Tmax, which leads to a large vehicle deceleration when the vehicle speed approaches zero and the vehicle brakes suddenly due to inertia, resulting in poor braking comfort.

[0006] Therefore, it can be seen that how to ensure that the pure electric heavy forklift can recover a large amount of kinetic energy during driving braking, slow down smoothly, achieve vehicle system safety and smooth operation, and improve the user experience is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this application is to provide a control method and device for the driving braking of an electric forklift, so that the pure electric heavy forklift can recover a large amount of kinetic energy and slow down smoothly during driving braking, improving the user experience.

[0008] To solve the above technical problems, this application provides a control method for the driving braking of an electric forklift, including:

[0009] Obtain the current braking pedal angle of the electric forklift;

[0010] Determine whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; wherein, the electro-hydraulic composite braking stage is the driving braking stage combining electric motor braking and hydraulic braking;

[0011] If it reaches, control the electric motor braking torque associated with the pedal angle not to exceed the maximum braking torque set in advance, and enter the step of determining whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage;

[0012] If it does not reach, determine that the driving braking stage corresponding to the current braking pedal angle is the pure electric motor braking stage, and select the smaller one of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor, so that the electric forklift can reduce the electric motor braking torque as the vehicle speed decreases.

[0013] Preferably, the control that the electric motor braking torque associated with the current pedal angle does not exceed the maximum braking torque set in advance includes:

[0014] Determine the first braking coefficient according to the preset braking distance and the driving braking energy recovery rate;

[0015] Calculate the electric motor braking torque associated with the pedal angle based on the first braking coefficient and the current braking pedal angle;

[0016] When the motor braking torque associated with the pedal angle reaches the maximum value of the preset braking torque, control the current motor braking torque associated with the pedal angle to be equal to the maximum value of the braking torque.

[0017] Preferably, selecting the smaller one 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 includes:

[0018] Determine a second braking coefficient according to the preset braking distance and the driving braking energy recovery rate;

[0019] Obtain the current motor speed of the electric forklift;

[0020] Calculate the motor braking torque associated with the motor speed based on the second braking coefficient and the current motor speed;

[0021] Judge whether the motor braking torque associated with the motor speed is less than the motor braking torque associated with the pedal angle;

[0022] If it is less, control the current braking torque of the motor to be equal to the motor braking torque associated with the motor speed.

[0023] Preferably, the maximum value of the preset braking torque is determined according to the driving braking energy recovery rate.

[0024] To solve the above technical problems, the present application also provides a control device for the driving braking of an electric forklift, including:

[0025] An acquisition module for acquiring the current braking pedal angle of the electric forklift;

[0026] A processing module for determining whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; wherein, the electro-hydraulic composite braking stage is a driving braking stage combining motor braking and hydraulic braking;

[0027] If it reaches, control the current motor braking torque associated with the pedal angle not to exceed the maximum value of the preset braking torque, and enter the step of determining whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage;

[0028] If it does not reach, determine that the driving braking stage corresponding to the current braking pedal angle is the pure motor braking stage, and select the smaller one 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, so that the electric forklift reduces the motor braking torque as the vehicle speed decreases.

[0029] To solve the above technical problems, the present application also provides a control device for electric forklift driving brakes, including a memory for storing a computer program;

[0030] a processor for implementing the steps of the control method for electric forklift driving brakes when executing the computer program.

[0031] A control method for electric forklift driving brakes provided by the present invention includes: obtaining the current braking pedal angle of the electric forklift, and determining whether the current driving brake stage reaches the electro-hydraulic composite braking stage according to the current braking pedal angle, where the electro-hydraulic composite braking stage is a driving brake stage combining electric motor braking and hydraulic braking. If the electro-hydraulic composite braking stage is reached, control the electric motor braking torque associated with the current pedal angle not to exceed the maximum preset braking torque, and continue to judge the current driving brake stage. If the electro-hydraulic composite braking stage is not reached, determine that the driving brake stage corresponding to the current braking pedal angle is the pure electric motor braking stage, and select the smaller of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor, so that the electric forklift reduces the electric motor braking torque as the vehicle speed decreases. It can be seen that in the electro-hydraulic composite braking stage of the technical solution provided by the present application, by controlling the electric motor braking torque associated with the current pedal angle not to exceed the maximum preset braking torque, it is avoided that the electric motor braking torque rapidly increases as the vehicle speed decreases during braking, and the phenomenon of sudden braking due to excessive braking torque occurs due to inertia when the vehicle speed approaches zero. In addition, in the pure electric motor braking stage, the smaller of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed is selected as the current braking torque of the motor, so that the electric motor braking torque decreases as the vehicle speed decreases smoothly, avoiding the sudden release of the drive shaft energy when the braking torque rapidly drops to zero, resulting in the forklift shaking, and thus improving the user experience.

[0032] In addition, the present application also provides a control device for electric forklift driving brakes, corresponding to the above control method for electric forklift driving brakes, with the same effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] To more clearly illustrate the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a characteristic curve diagram of motor speed and electric motor braking torque provided by the present application;

[0035] Figure 2The flowchart of a control method for the driving brake of an electric forklift provided by an embodiment of the present application;

[0036] Figure 3 The characteristic curve graph of the motor speed and the motor braking torque provided by an embodiment of the present application;

[0037] Figure 4 The structural diagram of a control device for the driving brake of an electric forklift provided by an embodiment of the present application;

[0038] Figure 5 The structural diagram of a control device for the driving brake of an electric forklift provided by another embodiment of the present application. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0040] The core of the present application is to provide a control method and device for the driving brake of an electric forklift. In the electro-hydraulic composite braking stage, by controlling the motor braking torque associated with the pedal angle not to exceed the maximum value of the preset braking torque, when the motor speed of the electric forklift approaches zero, the deceleration is large, and due to inertia, a sudden braking phenomenon occurs, resulting in poor braking comfort. In addition, in the pure electric motor braking stage, the smaller of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor speed is selected as the current braking torque of the motor, so that the electric forklift smoothly decelerates with the vehicle speed.

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0042] Electrified construction machinery is gradually entering the market. Among them, when an electric forklift is driving and braking, a large amount of kinetic energy is wasted by being converted into heat through friction braking. In addition, the converted heat causes the temperature of the hydraulic oil to rise, and at this time, additional energy needs to be consumed to dissipate the heat of the hydraulic oil. It can be seen that recovering energy during the driving brake of an electric forklift can improve the energy utilization rate of the power battery and extend the operation duration after the power battery is fully charged.

[0043] At present, electric forklifts usually use a single-pedal control to achieve driving braking. The single-pedal control method uses a speed control mode. After the user steps on the accelerator pedal to accelerate, releasing the accelerator pedal achieves driving braking and energy recovery. During this process, the speed of releasing the accelerator pedal determines the intensity of driving braking and the amount of energy recovered. That is, when the accelerator pedal is released gently, the braking intensity is low and the recovered energy is less. When the accelerator pedal is released quickly, the braking intensity is high and the recovered energy is more. It can be understood that when more energy needs to be recovered, the accelerator pedal needs to be released quickly, but high-intensity braking will lead to poor driving and handling comfort for the user due to inertia, and the single-pedal control method is only suitable for forklifts with a light body and a small tonnage. For forklifts with a large body weight and a large tonnage, on the one hand, the braking distance cannot be guaranteed, and on the other hand, the safety is low when the braking fails.

[0044] Therefore, at present, for forklifts with a large body weight and a large tonnage, a dual-pedal method with independent accelerator and brake pedals is usually used to achieve driving braking, and motor and hydraulic composite braking is used to achieve energy recovery. An angle sensor is installed on the brake pedal. Pure electric braking is used within a certain angle range, and motor and hydraulic composite braking is used within a certain angle range. For example, within the angle range of 0 to 40%, pure electric braking is used, and within the angle range of 60 to 100%, motor and hydraulic composite braking is used.

[0045] During the pure electric braking stage, the braking torque output by the motor is proportional to the brake pedal angle. When the forklift is moving forward and braking with the motor, the motor outputs a negative torque. When the motor speed is zero, if a negative torque is still output, it will cause the motor to accelerate in the opposite direction. At this time, the forklift accelerates backward, which is prone to danger. Therefore, usually, when the vehicle speed is close to zero, that is, when the motor speed is close to zero, the electric braking torque is cleared. Specifically, when the motor speed is N0, the electric braking torque -T is proportional to the brake pedal angle, where 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 electric braking torque is zero, that is, the motor does not work. When the motor speed is less than -N0, the electric braking torque is T. Since the energy on the drive shaft of the electric forklift is suddenly released after the electric braking torque drops from T to zero, it is easy to cause fluctuations in the motor speed. When the fluctuation range exceeds the range of the motor from -N0 to N0, the electric braking torque will correspondingly output a torque of T or -T, causing the electric braking torque to fluctuate continuously, which in turn causes the forklift to shake and reduces the user experience.

[0046] During the motor and hydraulic composite braking stage, as Figure 1 shown, the maximum value of the electric braking torque is Tmax, which is determined by Figure 1It can be known that during the driving braking process of the forklift, when the motor speed gradually decreases from 100%, the motor braking torque Tpeak gradually increases. When the speed reaches about 25%, the motor braking torque reaches the maximum value Tmax. Until the speed approaches zero, the motor still provides a huge braking torque, which causes the vehicle deceleration to be very large when the vehicle speed approaches zero, and the vehicle brakes suddenly due to inertia, resulting in poor braking comfort.

[0047] In order to make the electric forklift decelerate smoothly during the entire braking process, improve the energy recovery rate, and thus improve the user experience, the embodiment of the present application provides a control method for the driving braking of an electric forklift. During the electro-hydraulic compound braking stage, the motor braking torque associated with the pedal angle is controlled not to exceed the maximum preset braking torque. And during the pure electric motor braking stage, the smaller of the motor braking torque associated with the pedal angle and the motor braking torque associated with the motor speed is selected as the current braking torque of the motor, to avoid sudden braking and jitter during the braking process of the electric forklift and improve the user's driving braking experience.

[0048] Figure 2 The flowchart of a control method for the driving braking of an electric forklift provided by the embodiment of the present application is as Figure 2 shown, and the method includes:

[0049] S10: Obtain the current braking pedal angle of the electric forklift.

[0050] S11: Determine whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic compound braking stage; wherein, the electro-hydraulic compound braking stage is the driving braking stage combining motor braking and hydraulic braking. If it reaches, enter step S12; if not, enter step S13.

[0051] In a specific embodiment, for an electric forklift that realizes driving braking by adopting a dual-pedal method with independent acceleration and braking pedals, during driving braking, the current driving braking stage of the forklift can be determined according to the angle of the braking pedal pressed by the user. Therefore, in step S10, obtain the current braking pedal angle of the electric forklift, and determine whether the corresponding driving braking stage reaches the electro-hydraulic compound braking stage according to the current braking pedal angle.

[0052] It can be understood that the electro-hydraulic compound braking stage is the driving braking stage combining motor braking and hydraulic braking. In addition to the electro-hydraulic compound braking stage, there is also a pure electric motor braking stage. The current driving braking stage of the electric forklift can be determined according to the angle of the pedal. For example, the angle of 0-15 degrees is the pure electric motor braking stage, and more than 15 degrees is the electro-hydraulic compound braking stage. The present application does not limit the angle range corresponding to the pure electric motor braking stage and the angle range corresponding to the electro-hydraulic compound braking stage.

[0053] S12: If it is reached, control the braking torque of the motor currently associated with the pedal angle not to exceed the maximum value of the preset braking torque, and enter step S11.

[0054] When the current braking pedal angle reaches the electro-hydraulic composite braking stage, it can be determined that the electric forklift is in the braking stage of the combination of electric motor braking and hydraulic braking. As Figure 1 shown, during the braking process, as the rotational speed of the vehicle-mounted motor continuously decreases, the braking torque Tpeak of the motor will continuously increase. In order to avoid the braking torque of the motor reaching Tmax when the motor speed approaches 0, which may cause the forklift to suddenly brake due to inertia when it is about to stop quickly, and even cause the goods on the electric forklift to fall due to inertia, resulting in potential safety hazards and reducing the user experience. Therefore, in the electro-hydraulic composite braking stage of this application, control the braking torque of the motor currently associated with the pedal angle not to exceed the maximum value of the preset braking torque.

[0055] Figure 3 This is a characteristic curve graph of the motor speed and the braking torque of the motor provided by the embodiment of this application. As Figure 3 shown, as the motor speed decreases and the braking torque Tpeak of the motor continuously increases, control the braking torque Tpeak of the motor not to exceed the maximum value Tlimit of the preset braking torque. In fact, the maximum braking torque Tlimit is the upper limit for restricting the braking torque Tpeak of the motor. In order to avoid the electric forklift from suddenly braking when the braking torque Tpeak of the motor reaches Tmax, when the braking torque Tpeak of the motor reaches the maximum braking torque Tlimit, control the braking torque of the motor currently associated with the pedal angle to be equal to the maximum braking torque Tlimit. Thus, as the motor speed continuously decreases, the braking torque of the motor will not increase sharply, avoiding the phenomenon of sudden braking due to excessive braking torque and excessive deceleration when the motor speed approaches 0, improving the braking comfort and braking safety at the same time.

[0056] In fact, during driving braking, sometimes when encountering an obstacle ahead, the braking pedal will be depressed to brake. When the obstacle is cleared, the braking pedal will be gradually released to continue driving. At this time, the current braking pedal angle may gradually decrease to the current corresponding driving braking stage and enter the pure electric motor braking stage. Therefore, it is necessary to execute step S12 in real time to determine the driving braking stage corresponding to the current braking pedal angle.

[0057] S13: Determine that the driving braking stage corresponding to the current braking pedal angle is the pure electric motor braking stage, and select the smaller value between the braking torque of the motor associated with the pedal angle and the braking torque of the motor associated with the motor speed as the current braking torque of the motor, so that the braking torque of the electric forklift decreases as the vehicle speed decreases.

[0058] During implementation, in the pure electric motor braking stage, to avoid the electric motor braking torque being cleared when the motor speed approaches zero, which may cause the electric forklift to shake. Therefore, in the embodiments of this application, after determining that the current driving braking stage corresponding to the current brake pedal angle is the pure electric motor braking stage, the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed are respectively obtained, and the smaller electric motor braking torque is selected as the current braking torque of the motor. In fact, as the motor speed gradually decreases, the electric motor braking torque associated with the motor speed is less than the electric motor braking torque associated with the pedal angle. At this time, the braking torque of the motor can gradually decrease smoothly with the motor speed, avoiding the sudden release of energy on the drive shaft of the electric forklift, which may otherwise cause fluctuations in the motor speed.

[0059] It can be understood that when the driving braking distance is larger, the vehicle travels more smoothly with good comfort, but the energy recovery rate of the electric forklift is low. If the driving braking distance is larger, the vehicle has a large driving inertia and poor comfort, but the energy recovery rate of the electric forklift is high. Therefore, the maximum braking torque Tlimit is less than Tmax, and when setting the maximum braking torque Tlimit, it needs to be set according to the actual requirements of the energy recovery rate.

[0060] The control method for the driving braking of the electric forklift provided by the embodiments of this application includes: obtaining the current brake pedal angle of the electric forklift, and determining whether the current driving braking stage has reached the electro-hydraulic composite braking stage according to the current brake pedal angle, where the electro-hydraulic composite braking stage is a driving braking stage that combines electric motor braking and hydraulic braking. If the electro-hydraulic composite braking stage is reached, control the electric motor braking torque associated with the current pedal angle not to exceed the preset maximum braking torque, and continue to judge the current driving braking stage. If the electro-hydraulic composite braking stage is not reached, determine that the driving braking stage corresponding to the current brake pedal angle is the pure electric motor braking stage, and select the smaller of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor, so that the electric motor braking torque of the electric forklift decreases as the vehicle speed decreases. It can be seen that in the electro-hydraulic composite braking stage, the technical solution provided by this application avoids the rapid increase in the electric motor braking torque as the vehicle speed decreases during braking by controlling the electric motor braking torque associated with the current pedal angle not to exceed the preset maximum braking torque, and avoids the phenomenon of sudden braking due to excessive inertia caused by the excessive braking torque when the vehicle speed approaches zero. In addition, in the pure electric motor braking stage, selecting the smaller of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor makes the electric motor braking torque decrease smoothly as the vehicle speed decreases, avoiding the sudden release of the drive shaft energy when the braking torque quickly drops to zero, which may cause the forklift to shake, thereby improving the user experience.

[0061] In a specific implementation, when controlling the electric motor braking torque associated with the pedal angle not to exceed the maximum value of the preset braking torque, the electric motor braking torque Tp associated with the pedal angle is determined according to the formula Tp = k1 * A, where k1 is the first braking coefficient and A is the current pedal braking angle.

[0062] It should be noted that the first braking coefficient k1 is related to the driving braking distance and the energy recovery rate of the electric forklift. Therefore, it is necessary to first determine the first braking coefficient according to the preset braking distance and the driving braking energy recovery rate, and calculate the electric motor braking torque Tp associated with the pedal angle based on the first braking coefficient k1 and the current braking pedal angle A.

[0063] When the electric motor braking torque Tp associated with the pedal angle reaches the maximum value Tlimit of the preset braking torque as Figure 3 shown, control Tp = Tlimit, thereby avoiding the braking torque Tp exceeding Tlimit as the motor speed decreases, resulting in too large a deceleration when the motor speed approaches 0, and the electric forklift making an emergency brake limit due to inertia.

[0064] The control method for the driving braking of the electric forklift provided by the embodiment of the present application determines the first braking coefficient according to the preset braking distance and the driving braking energy recovery rate, calculates the electric motor braking torque associated with the pedal angle based on the first braking coefficient and the current braking pedal angle, and when the electric motor braking torque associated with the pedal angle reaches the maximum value of the preset braking torque, controls the electric motor braking torque currently associated with the pedal angle to be equal to the maximum value of the braking torque, thereby avoiding the phenomenon that in the electro-hydraulic composite braking stage of the electric forklift, as the motor speed continuously decreases, the electric motor braking torque continuously increases and the deceleration also continuously increases, resulting in an emergency brake due to inertia when the motor speed approaches 0, improving the driving braking comfort of the electric forklift while enhancing the driving braking safety.

[0065] On the basis of the above embodiment, if it is determined according to the current pedal braking angle that the current corresponding driving braking stage is the pure electric motor braking stage, in addition to obtaining the electric motor braking torque associated with the pedal angle, the electric motor braking torque Ts associated with the motor speed is determined according to the formula Ts = k2 * N0, where k2 is the second braking coefficient and N0 is the current motor speed of the electric forklift.

[0066] Similarly, it is necessary to determine the second braking coefficient k2 according to the preset braking distance and the driving braking energy recovery rate, and calculate the electric motor braking torque Ts associated with the motor speed based on the second braking coefficient k2 and the obtained current motor speed N0 of the electric forklift.

[0067] In fact, during the braking process, when the motor speed reaches a certain value, the motor braking torque Ts associated with the motor speed must be less than the motor braking torque Tp associated with the pedal angle. Therefore, during the pure electric motor braking phase, the smaller of Ts and Tp is selected as the current braking torque of the motor, that is, it is determined whether the motor braking torque Ts associated with the motor speed is less than the motor braking torque Tp associated with the pedal angle. If it is less, the current braking torque of the motor is controlled to be equal to the motor braking torque Ts associated with the motor speed. Thus, the actual braking torque of the motor decreases smoothly as the motor speed continuously decreases. This avoids suddenly clearing the motor braking torque when the motor speed approaches 0, resulting in a sudden release of the energy on the drive shaft of the electric forklift and causing the electric forklift to vibrate.

[0068] It should be noted that the pre-set maximum braking torque Tlimit limits the upper limit of the electric forklift during the electro-hydraulic composite braking phase, and the motor braking torque Ts associated with the motor speed is a process of slowly decreasing the motor braking torque according to the motor speed N.

[0069] The control method for the driving braking of the electric forklift provided by the embodiment of the present application determines the second braking coefficient according to the pre-set braking distance and the driving braking energy recovery rate, and obtains the current motor speed of the electric forklift. The motor braking torque associated with the motor speed is calculated based on the second braking coefficient and the current motor speed. When the motor braking torque associated with the motor speed is less than the motor braking torque associated with the pedal angle, the current braking torque of the motor is controlled to be equal to the motor braking torque associated with the motor speed. Thus, the motor braking torque of the electric forklift is associated with the motor speed, that is, the motor braking torque is controlled to decrease smoothly with the motor speed, avoiding the sudden release of the energy on the drive shaft when the motor braking torque is cleared at one time and causing the electric forklift to vibrate, thereby improving the user experience.

[0070] In specific implementation, if more energy is to be recovered during the driving braking of the electric forklift, the braking distance of the driving braking is shorter, but the braking comfort due to inertia is poor. On the contrary, if the braking distance of the driving braking is longer, the braking comfort of the vehicle during driving braking is better, but the energy recovery rate is lower. And the maximum braking torque is related to the driving braking energy recovery rate. Therefore, when setting the maximum braking torque, it is necessary to comprehensively determine according to the actual energy recovery rate requirement and the braking distance of the driving braking.

[0071] The control method for the driving braking of the electric forklift provided by the embodiment of the present application determines the pre-set maximum braking torque according to the driving braking energy recovery rate, ensuring the braking comfort during driving while recovering as much energy as possible, and further improving the user experience of using the electric forklift.

[0072] In the above embodiments, a control method for the driving brake of an electric forklift has been described in detail. The present application also provides an embodiment corresponding to a control device for the driving brake of an electric forklift. It should be noted that the present application describes the embodiments of the device part from two perspectives, one is from the perspective of functional modules, and the other is from the perspective of hardware structure.

[0073] Figure 4 The following is a structural diagram of a control device for the driving brake of an electric forklift provided by an embodiment of the present application. As Figure 4 shown, the device includes:

[0074] An acquisition module 10, configured to acquire the current braking pedal angle of the electric forklift.

[0075] A processing module 11, configured to determine whether the driving brake stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; wherein, the electro-hydraulic composite braking stage is a driving brake stage combining electric motor braking and hydraulic braking. If it reaches, control the electric motor braking torque associated with the pedal angle not to exceed the maximum braking torque set in advance, and enter the step of determining whether the driving brake stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage. If it does not reach, determine that the driving brake stage corresponding to the current braking pedal angle is the pure electric motor braking stage, and select the smaller one of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor, so that the electric forklift reduces the electric motor braking torque as the vehicle speed decreases.

[0076] Since the embodiments of the device part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the device part, and will not be elaborated here.

[0077] The control device for the driving brake of an electric forklift provided by an embodiment of the present application includes: obtaining the current brake pedal angle of the electric forklift, and determining whether the current driving brake stage reaches the electro-hydraulic compound braking stage according to the current brake pedal angle, where the electro-hydraulic compound braking stage is the driving brake stage combining electric motor braking and hydraulic braking. If the electro-hydraulic compound braking stage is reached, control the electric motor braking torque associated with the current pedal angle not to exceed the maximum preset braking torque, and continue to judge the current driving brake stage. If the electro-hydraulic compound braking stage is not reached, determine that the driving brake stage corresponding to the current brake pedal angle is the pure electric motor braking stage, and select the smaller one of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor, so that the electric motor braking torque of the electric forklift decreases as the vehicle speed decreases. It can be seen that in the electro-hydraulic compound braking stage, by controlling the electric motor braking torque associated with the current pedal angle not to exceed the maximum preset braking torque, the rapid increase of the electric motor braking torque as the vehicle speed decreases during braking is avoided, and the phenomenon of sudden braking due to excessive braking torque when the vehicle speed approaches zero is avoided. In addition, in the pure electric motor braking stage, selecting the smaller one of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor makes the electric motor braking torque decrease as the vehicle speed decreases gently, avoiding the sudden release of the drive shaft energy when the braking torque quickly drops to zero, which causes the forklift to shake, and thus improving the user experience.

[0078] Figure 5 The structure diagram of a control device for the driving brake of an electric forklift provided by another embodiment of the present application is as Figure 5 shown. The control device for the driving brake of an electric forklift includes: a memory 20 for storing a computer program;

[0079] a processor 21 for implementing the steps of the control method for the driving brake of an electric forklift as mentioned in the above embodiment when executing the computer program.

[0080] The control device for the driving brake of an electric forklift provided in this embodiment may include, but is not limited to, a smart phone, a tablet computer, a notebook computer, a desktop computer, etc.

[0081] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 may be implemented in at least one hardware form of a Digital Signal Processor (DSP), a Field-Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the wake state, also known as the Central Processing Unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a Graphics Processing Unit (GPU), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may further include an Artificial Intelligence (AI) processor, and the AI processor is used to process computational operations related to machine learning.

[0082] The memory 20 may include one or more computer-readable storage media, and the computer-readable storage media may be non-transitory. The memory 20 may further include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash storage devices. In this embodiment, the memory 20 is at least used to store the following computer program 201. After the computer program is loaded and executed by the processor 21, it can implement the relevant steps of the control method for the electric forklift driving brake disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 20 may further include an operating system 202 and data 203, etc., and the storage method may be transient storage or permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. The data 203 may include, but is not limited to, the relevant data involved in the control method for the electric forklift driving brake.

[0083] In some embodiments, the control device for the electric forklift driving brake may further include a display screen 22, an input / output interface 23, a communication interface 24, a power supply 25, and a communication bus 26.

[0084] Those skilled in the art can understand that Figure 5 the structure shown in

[0085] The control device for the driving brake of an electric forklift provided by an embodiment of the present application includes a memory and a processor. When the processor executes the program stored in the memory, the following method can be implemented: the control method for the driving brake of an electric forklift.

[0086] In the electro-hydraulic composite braking stage, the control device for the driving brake of an electric forklift provided by an embodiment of the present application avoids the rapid increase of the electric motor braking torque during braking as the vehicle speed decreases, and the occurrence of sudden braking due to excessive braking torque inertia when the vehicle speed approaches zero by controlling the electric motor braking torque associated with the pedal angle not to exceed the maximum preset braking torque. In addition, in the pure electric motor braking stage, the smaller of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed is selected as the current braking torque of the motor, so that the electric motor braking torque decreases as the vehicle speed decreases gently, avoiding the sudden release of the drive shaft energy when the braking torque quickly drops to zero, which may cause the forklift to shake, and thus improving the user experience.

[0087] The above provides a detailed introduction to a control method and device for the driving brake of an electric forklift provided by the present application. The embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, refer to the description of the method part. It should be noted that for those of ordinary skill in the art in the technical field of the present application, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0088] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, the element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

Claims

1. A control method for the driving brake of an electric forklift, characterized in that, Including: Obtain the current braking pedal angle of the electric forklift; Determine whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; wherein, the electro-hydraulic composite braking stage is a driving braking stage combining electric motor braking and hydraulic braking; If it reaches, control the electric motor braking torque currently associated with the pedal angle not to exceed the maximum braking torque preset, and enter the step of determining whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; the maximum braking torque is less than the maximum electric motor braking torque; controlling the electric motor braking torque currently associated with the pedal angle not to exceed the maximum braking torque preset includes: determining a first braking coefficient according to the preset braking distance and the driving braking energy recovery rate; calculating the electric motor braking torque associated with the pedal angle based on the first braking coefficient and the current braking pedal angle; when the electric motor braking torque associated with the pedal angle reaches the preset maximum braking torque, control the current electric motor braking torque associated with the pedal angle to be equal to the maximum braking torque; If it does not reach, determine that the driving braking stage corresponding to the current braking pedal angle is the pure electric motor braking stage, and select the smaller one of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor, so that the electric motor braking torque of the electric forklift decreases with the vehicle speed; selecting the smaller one of the electric motor braking torque associated with the pedal angle and the electric motor braking torque associated with the motor speed as the current braking torque of the motor includes: determining a second braking coefficient according to the preset braking distance and the driving braking energy recovery rate; obtaining the current motor speed of the electric forklift; calculating the electric motor braking torque associated with the motor speed based on the second braking coefficient and the current motor speed; judging whether the electric motor braking torque associated with the motor speed is less than the electric motor braking torque associated with the pedal angle.

2. The control method for the driving brake of an electric forklift according to claim 1, characterized in that, The preset maximum braking torque is determined according to the driving braking energy recovery rate.

3. A control device for the driving brake of an electric forklift, characterized in that, Including: An acquisition module for obtaining the current braking pedal angle of the electric forklift; A processing module for determining whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; wherein, the electro-hydraulic composite braking stage is a driving braking stage combining electric motor braking and hydraulic braking; If it is reached, control the braking torque of the motor associated with the current pedal angle not to exceed the maximum value of the preset braking torque, and enter the step of determining whether the driving braking stage corresponding to the current braking pedal angle reaches the electro-hydraulic composite braking stage; the maximum value of the braking torque is less than the maximum value of the motor braking torque; controlling the braking torque of the motor associated with the current pedal angle not to exceed the maximum value of the preset braking torque includes: determining a first braking coefficient according to the preset braking distance and the driving braking energy recovery rate; calculating the braking torque of the motor associated with the pedal angle based on the first braking coefficient and the current braking pedal angle; when the braking torque of the motor associated with the pedal angle reaches the maximum value of the preset braking torque, control the current braking torque of the motor associated with the pedal angle to be equal to the maximum value of the braking torque; If it is not reached, determine that the driving braking stage corresponding to the current braking pedal angle is the pure electric motor braking stage, and select the smaller of the braking torque of the motor associated with the pedal angle and the braking torque of the motor associated with the motor speed as the current braking torque of the motor, so that the braking torque of the electric forklift decreases with the decrease of the vehicle speed; selecting the smaller of the braking torque of the motor associated with the pedal angle and the braking torque of the motor associated with the motor speed as the current braking torque of the motor includes: determining a second braking coefficient according to the preset braking distance and the driving braking energy recovery rate; obtaining the current motor speed of the electric forklift; calculating the braking torque of the motor associated with the motor speed based on the second braking coefficient and the current motor speed; judging whether the braking torque of the motor associated with the motor speed is less than the braking torque of the motor associated with the pedal angle.

4. A control device for the driving brake of an electric forklift, characterized in that, It includes a memory for storing a computer program; A processor for implementing the steps of the control method for driving braking of an electric forklift as described in any one of claims 1 to 2 when executing the computer program.

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