Fault handling method and system for an energy recovery system of an electric forklift

Abstract

The present application discloses a fault handling method and system for an energy recovery system of an electric forklift, and the technical field to which it belongs is forklift control technology. The fault handling method for the energy recovery system of the electric forklift includes: determining whether there is a fault in the energy recovery system of the electric forklift; if so, determining the fault level and setting the fault with the highest level as the core fault; if the forklift is in a driving state and the level of the core fault is lower than or equal to a preset level, then after receiving a braking instruction, controlling the drive motor and / or the electro-hydraulic proportional valve to perform braking according to the pedal angle of the electric brake pedal; if the forklift is in a driving state and the level of the core fault is higher than the preset level, then after receiving a braking instruction, controlling the drive motor and / or the electro-hydraulic proportional valve to perform braking according to the fault type of the core fault. The present application can perform reasonable braking control after a forklift fails, improving the safety of forklift driving.

Description

Technical Field

[0001] The present application relates to the technical field of forklift control, and particularly relates to a fault handling method and system for an energy recovery system of an electric forklift. Background Art

[0002] With the rapid development of the logistics industry, electric special operation equipment such as forklifts plays an increasingly important role in material handling operations. However, forklifts need to start and stop frequently during operations, resulting in the waste of kinetic energy being converted into heat through friction during braking. In addition, the converted heat causes the hydraulic oil to overheat, and additional energy is consumed to dissipate the heat of the hydraulic oil.

[0003] In related technologies, there is a solution to use an energy recovery system (i.e., an electric braking system) of an electric forklift to recover kinetic energy. However, during the use of the energy recovery system of the electric forklift, it is inevitable that faults such as the electric braking pedal angle sensor, motor, battery, proportional valve, communication, etc. occur. If the above faults are not handled correspondingly and in a timely manner, it is very easy to cause safety accidents.

[0004] Therefore, how to perform reasonable braking control after a forklift fails and improve the driving safety of the forklift is a technical problem that needs to be solved by those skilled in the art currently. Summary of the Invention

[0005] The purpose of the present application is to provide a fault handling method and system for an energy recovery system of an electric forklift, which can perform reasonable braking control after the forklift fails and improve the driving safety of the forklift.

[0006] To solve the above technical problems, the present application provides a fault handling method for an energy recovery system of an electric forklift, which is applied to a control device of the energy recovery system of the electric forklift. The energy recovery system of the electric forklift further includes a power battery, a drive motor, a brake, an electric braking pedal, a pedal angle sensor, and an electro-hydraulic proportional valve. The pedal angle sensor is used to detect the pedal angle of the electric braking pedal, and the electro-hydraulic proportional valve is used to control the braking force of the brake by adjusting the pressure of the hydraulic oil. The fault handling method for the energy recovery system of the electric forklift includes:

[0007] Judge whether there is a fault in the energy recovery system of the electric forklift;

[0008] If so, determine the fault level, and set the fault with the highest level as the core fault;

[0009] If the forklift is in a driving state and the level of the core fault is lower than or equal to a preset level, then after receiving a braking instruction, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the pedal angle of the electric braking pedal;

[0010] If the forklift is in a driving state and the level of the core fault is higher than the preset level, then after receiving a braking instruction, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault.

[0011] Optionally, controlling the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault includes:

[0012] If the fault type of the core fault is a pedal angle sensor fault, then determine a target braking torque according to the current vehicle speed of the forklift, and control the drive motor and / or the electro-hydraulic proportional valve to brake according to the target braking torque;

[0013] If the fault type of the core fault is an electro-hydraulic proportional valve fault, then control the drive motor to brake;

[0014] If the fault type of the core fault is a battery charge prohibition fault, a motor zero torque fault, or a communication fault, then control the electro-hydraulic proportional valve to brake.

[0015] Optionally, it further includes:

[0016] If the core fault includes an electro-hydraulic proportional valve fault and a preset fault, then generate an alarm message prompting the user to perform foot valve braking; where the preset fault includes any one or a combination of any several of a battery charge prohibition fault, a motor zero torque fault, and a communication fault.

[0017] Optionally, after setting the fault with the highest level as the core fault, it further includes:

[0018] If the forklift is in a stationary state and the level of the core fault is higher than the preset level, then turn off the electric braking function and generate a fault prompt message; where after turning off the electric braking function, the control device does not respond to the change in the pedal angle of the electric braking pedal.

[0019] Optionally, after generating the fault prompt message, it further includes:

[0020] If a forklift travel instruction is received, then determine whether the user inputs a response message corresponding to the fault prompt message;

[0021] If so, control the forklift to move according to the forklift travel instruction;

[0022] If not, then do not respond to the forklift travel instruction.

[0023] Optionally, after setting the fault with the highest level as the core fault, it further includes:

[0024] If the forklift is in a stationary state and the level of the core fault is lower than or equal to the preset level, a fault prompt message and fault handling suggestions are generated.

[0025] Optionally, the determining of the fault level includes:

[0026] If the faults existing in the energy recovery system of the electric forklift are filter fault, battery power limit fault or motor power limit fault, it is determined that the level of the fault is lower than or equal to the preset level;

[0027] If the faults existing in the energy recovery system of the electric forklift are pedal angle sensor fault, electro-hydraulic proportional valve fault, battery charge prohibition fault, motor zero torque fault or communication fault, it is determined that the level of the fault is higher than the preset level.

[0028] The present application also provides a fault handling system for an energy recovery system of an electric forklift, which is applied to a control device of the energy recovery system of the electric forklift. The energy recovery system of the electric forklift further includes a power battery, a drive motor, a brake, an electro-hydraulic brake pedal, a pedal angle sensor and an electro-hydraulic proportional valve. The pedal angle sensor is used to detect the pedal angle of the electro-hydraulic brake pedal, and the electro-hydraulic proportional valve is used to control the braking force of the brake by adjusting the pressure of the hydraulic oil. The fault handling system for the energy recovery system of the electric forklift includes:

[0029] A fault judgment module, which is used to judge whether there is a fault in the energy recovery system of the electric forklift;

[0030] A fault analysis module, which is used to determine the fault level if there is a fault in the energy recovery system of the electric forklift, and set the fault with the highest level as the core fault;

[0031] A first processing module, which is used to, if the forklift is in a driving state and the level of the core fault is lower than or equal to the preset level, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the pedal angle of the electro-hydraulic brake pedal after receiving a braking instruction;

[0032] A second processing module, which is used to, if the forklift is in a driving state and the level of the core fault is higher than the preset level, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault after receiving a braking instruction.

[0033] Optionally, the input end of the electro-hydraulic proportional valve is connected to an oil source, the output end of the electro-hydraulic proportional valve is connected to the input end of a shuttle valve, the output end of the shuttle valve is connected to the brake, and the brake is a wet brake.

[0034] Optionally, it further includes a foot brake valve. The input end of the foot brake valve is connected to an oil source, the output end of the foot brake valve is connected to the input end of a shuttle valve, and the output end of the shuttle valve is connected to the brake.

[0035] This application provides a method for handling faults in an energy recovery system of an electric forklift. The energy recovery system of the electric forklift includes a power battery, a drive motor, a brake, an electric brake pedal, a pedal angle sensor, and an electro-hydraulic proportional valve. After detecting a fault in the energy recovery system of the electric forklift, the fault level is determined and the fault with the highest level is set as the core fault to distinguish the impact of the fault on safety and avoid overreaction or brake failure. Specifically, when the forklift is in a driving state and the level of the core fault is lower than or equal to a preset level, if a braking instruction is received, the drive motor and / or the electro-hydraulic proportional valve are controlled to brake according to the pedal angle of the electric brake pedal; when the forklift is in a driving state and the level of the core fault is higher than the preset level, if a braking instruction is received, the drive motor and / or the electro-hydraulic proportional valve are controlled to brake according to the fault type of the core fault. It can be seen that when the fault in the energy recovery system of the electric forklift is lower than or equal to the preset level, the normal braking function is maintained and the energy recovery ability is maximally retained; when the fault in the energy recovery system of the electric forklift is higher than the preset level, the braking reliability is preferentially ensured. Therefore, this application can perform reasonable braking control after a fault occurs in the forklift and improve the driving safety of the forklift. This application also provides a fault handling system for an energy recovery system of an electric forklift, which has the above beneficial effects and will not be elaborated here. Description of the Drawings

[0036] To more clearly illustrate the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a schematic diagram of the principle of an energy recovery system of an electric forklift provided by an embodiment of this application;

[0038] Figure 2 It is a flowchart of a method for handling faults in an energy recovery system of an electric forklift provided by an embodiment of this application;

[0039] Figure 3 It is a control flowchart for handling faults in a kinetic energy recovery system provided by an embodiment of this application. Detailed Embodiments

[0040] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this application without creative efforts shall fall within the scope of protection of this application.

[0041] Please refer to Figure 1 , Figure 1 which is a schematic diagram of the principle of an energy recovery system for an electric forklift provided by an embodiment of this application. The energy recovery system for an electric forklift is also known as an electro-hydraulic composite braking system for a heavy-duty electric forklift. This system includes a control device (i.e., the vehicle-mounted controller VCU, Vehicle Control Unit) 1, an accelerator pedal 2, an electro-hydraulic brake pedal (including a brake pedal angle sensor) 3, an electro-hydraulic proportional valve (also known as a proportional pressure reducing valve) 4, a foot brake valve 5, a shuttle valve 6, an oil source 7, a vehicle-mounted instrument 8, a power battery 9, a motor (i.e., a drive motor) and its controller 10, a parking hydraulic brake 11, a differential 12, and a wet brake 13. The power battery can perform charging and discharging operations with the drive motor. The electro-hydraulic brake pedal can transmit signal 1 and signal 2 to the control device, and signal 1 and signal 2 can correspond to different pedal angles. The figure shows the VCU input and output lines, CAN (Controller Area Network, controller area network bus) control lines, and there can be hydraulic connections, mechanical connections, or high-voltage connections between various devices. The motor drive walking system includes a drive axle with a wet brake, a differential, a parking brake, and a drive motor and its controller. The accelerator pedal and the brake pedal angle sensor are connected to the signal input end of the control device, the output end of the control device is connected to the electro-hydraulic proportional valve, the oil source is connected to the input ends of the electro-hydraulic proportional valve and the foot brake valve, the output ends of both are connected to the input end of the shuttle valve, the output end of the shuttle valve is connected to the wet brake of the vehicle drive axle, and the vehicle-mounted instrument and the drive motor control device perform information interaction with the electro-hydraulic proportional valve through the CAN bus, and the power battery is connected to the motor controller through a high-voltage line.

[0042] Next, please refer to Figure 2 , Figure 2 which is a flowchart of a fault handling method for an energy recovery system of an electric forklift provided by an embodiment of this application.

[0043] The specific steps may include:

[0044] S201: Determine whether there is a fault in the energy recovery system of the electric forklift; if so, proceed to S202; if not, end the process.

[0045] Among them, this embodiment can be applied to the control device of the energy recovery system of an electric forklift. The above-mentioned energy recovery system of the electric forklift further includes a power battery, a drive motor, a brake, an electro-hydraulic brake pedal, a pedal angle sensor, and an electro-hydraulic proportional valve. The pedal angle sensor is used to detect the pedal angle of the electro-hydraulic brake pedal, and the electro-hydraulic proportional valve is used to control the braking force of the brake by adjusting the pressure of the hydraulic oil. The above control device can be a vehicle controller VCU (Vehicle Control Unit). The above forklift can be an electric forklift powered by a power battery and driven by a drive motor, such as a heavy-duty electric forklift. The above brake can be a wet brake.

[0046] The above brake can be a brake in the motor-driven walking system. The brake can be installed at the wheel end of the drive axle. The brake is connected to the electro-hydraulic proportional valve through a pipeline. The electro-hydraulic proportional valve is a control valve that can adjust the pressure or flow rate of the hydraulic oil according to the input signal (current or voltage). The electro-hydraulic proportional valve can control the braking force of the brake by adjusting the pressure of the hydraulic oil, so as to achieve braking.

[0047] This step can detect by real-time monitoring the state parameters of key components in the energy recovery system of the electric forklift and combining with the preset fault diagnosis logic, so as to judge whether there is a fault in the energy recovery system of the electric forklift. The above key components can include a pedal angle sensor, an electro-hydraulic proportional valve, a battery, a drive motor, etc.

[0048] S202: Determine the fault level, and set the fault with the highest level as the core fault.

[0049] Among them, this step is based on the premise that there is a fault in the energy recovery system of the electric forklift. The energy recovery system of the electric forklift can have any number of faults at the same time, and each fault has its corresponding fault level. This embodiment can pre-store the corresponding relationship between the fault types and the fault levels, and determine the fault level of each fault in the energy recovery system of the electric forklift based on this corresponding relationship. This step can set the fault with the highest level in the energy recovery system of the electric forklift as the core fault.

[0050] When the driver steps on the electro-hydraulic brake pedal, the control device receives a braking instruction. When the forklift is in a driving state and there is a fault, the braking can be carried out according to the strategy of S203 or S204.

[0051] S203: If the forklift is in a driving state and the level of the core fault is lower than or equal to the preset level, then after receiving the braking instruction, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the pedal angle of the electro-hydraulic brake pedal.

[0052] Among them, if the forklift is in a driving state and the level of the core fault is lower than or equal to the preset level, it indicates that there is a fault in the electric forklift energy recovery system during the driving process of the forklift, and the fault with the highest fault level is lower than or equal to the preset level; in the above situation, the drive motor and / or the electro-hydraulic proportional valve can be controlled to brake according to the pedal angle of the electro-brake pedal.

[0053] Specifically, in this embodiment, the total target braking torque can be calculated according to the pedal angle (i.e., pedal opening) and the braking torque curve, and the control is performed according to the following strategy A1, strategy A2 or strategy A3:

[0054] Strategy A1: In this embodiment, the drive motor can be controlled to brake according to the total target braking torque. At this time, the torque output by the drive motor reaches the total target braking torque.

[0055] Strategy A2: In this embodiment, the valve opening of the electro-hydraulic proportional valve can be adjusted so that the brake brakes according to the total target braking torque. At this time, the torque output by the brake reaches the total target braking torque.

[0056] Strategy A3: In this embodiment, the drive motor can be controlled to brake according to the first torque value, and the valve opening of the electro-hydraulic proportional valve can be adjusted so that the brake brakes according to the second torque value. At this time, the torque output by the drive motor reaches the first torque value, the torque output by the brake reaches the second torque value, and the sum of the first torque value and the second torque value is equal to the total target braking torque.

[0057] S204: If the forklift is in a driving state and the level of the core fault is higher than the preset level, then after receiving the braking instruction, the drive motor and / or the electro-hydraulic proportional valve are controlled to brake according to the fault type of the core fault.

[0058] Among them, if the forklift is in a driving state and the level of the core fault is higher than the preset level, it indicates that there is a fault in the electric forklift energy recovery system during the driving process of the forklift, and the fault with the highest fault level is higher than the preset level; in the above situation, the drive motor and / or the electro-hydraulic proportional valve can be controlled to brake according to the fault type of the core fault. In this embodiment, the corresponding relationship between faults higher than the preset level and braking strategies can be stored in advance, and based on this corresponding relationship, the drive motor and / or the electro-hydraulic proportional valve can be controlled to brake.

[0059] The above control of the electro-hydraulic proportional valve to brake specifically means: by adjusting the current signal of the electro-hydraulic proportional valve to change the valve opening, thereby adjusting the pressure of the hydraulic oil so that the brake brakes according to the corresponding torque.

[0060] This embodiment provides a fault handling method for an energy recovery system of an electric forklift. The energy recovery system of the electric forklift includes a power battery, a drive motor, a brake, an electric brake pedal, a pedal angle sensor, and an electro-hydraulic proportional valve. After detecting a fault in the energy recovery system of the electric forklift, the fault level is determined and the fault with the highest level is set as the core fault to distinguish the impact of the fault on safety and avoid overreaction or brake failure. Specifically, when the forklift is in a driving state and the level of the core fault is lower than or equal to a preset level, if a braking instruction is received, the drive motor and / or the electro-hydraulic proportional valve are controlled to brake according to the pedal angle of the electric brake pedal; when the forklift is in a driving state and the level of the core fault is higher than the preset level, if a braking instruction is received, the drive motor and / or the electro-hydraulic proportional valve are controlled to brake according to the fault type of the core fault. It can be seen that in this embodiment, when the fault of the energy recovery system of the electric forklift is lower than or equal to the preset level, the normal braking function is maintained and the energy recovery ability is maximally retained; when the fault of the energy recovery system of the electric forklift is higher than the preset level, the braking reliability is ensured first. Therefore, this embodiment can perform reasonable braking control after a fault occurs in the forklift and improve the driving safety of the forklift.

[0061] As a further introduction to the corresponding embodiment, controlling the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault includes the following strategies: Figure 1 As a further introduction to the corresponding embodiment, controlling the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault includes the following strategies:

[0062] Strategy B1: If the fault type of the core fault is a pedal angle sensor fault, determine the target braking torque according to the current vehicle speed of the forklift, and control the drive motor and / or the electro-hydraulic proportional valve to brake according to the target braking torque.

[0063] If the pedal angle sensor fails, the accurate pedal angle cannot be detected. At this time, the target braking torque is determined according to the current vehicle speed of the forklift. This embodiment can store the correspondence between the vehicle speed and the braking torque, and determine the target braking torque based on this correspondence.

[0064] Specifically, this embodiment can control the drive motor to brake according to the target braking torque. At this time, the torque output by the drive motor reaches the target braking torque. This embodiment can adjust the valve opening of the electro-hydraulic proportional valve so that the brake brakes according to the target braking torque. At this time, the torque output by the brake reaches the target braking torque. This embodiment can control the drive motor to brake according to a third torque value, adjust the valve opening of the electro-hydraulic proportional valve so that the brake brakes according to a fourth torque value. At this time, the torque output by the drive motor reaches the third torque value, the torque output by the brake reaches the fourth torque value, and the sum of the third torque value and the fourth torque value is equal to the target braking torque.

[0065] Strategy B2: If the fault type of the core fault is an electro-hydraulic proportional valve fault, then control the drive motor to brake.

[0066] If there is an electro-hydraulic proportional valve fault, braking cannot be achieved through the electro-hydraulic proportional valve. At this time, only the drive motor is used for braking. Specifically, the drive motor can be controlled to brake according to any one or a combination of several of the pedal angle, motor state, battery state, and vehicle speed.

[0067] Strategy B3: If the fault type of the core fault is a battery charging prohibition fault, a motor zero torque fault, or a communication fault, then control the electro-hydraulic proportional valve to brake.

[0068] If there is a battery charging prohibition fault, a motor zero torque fault, or a communication fault, braking cannot be achieved through the drive motor. At this time, only the electro-hydraulic proportional valve is used for braking. Specifically, the electro-hydraulic proportional valve can be controlled to brake according to any one or a combination of several of the pedal angle, motor state, battery state, and vehicle speed.

[0069] Further, if the core fault includes both an electro-hydraulic proportional valve fault and a preset fault at the same time, braking cannot be achieved through the drive motor or the electro-hydraulic proportional valve at this time. An alarm message prompting the user to perform foot valve braking can be generated at this time so that the user can brake through the foot brake valve; wherein, the preset fault includes any one or a combination of several of a battery charging prohibition fault, a motor zero torque fault, and a communication fault.

[0070] As a further introduction to the Figure 1 corresponding embodiment, after setting the fault with the highest level as the core fault, if the forklift is in a stationary state and the level of the core fault is higher than the preset level, the electric braking function is turned off, and a fault prompt message is generated; wherein, after turning off the electric braking function, the control device does not respond to the change in the pedal angle of the electric braking pedal.

[0071] If the forklift is in a stationary state and the level of the core fault is higher than the preset level, it means that the forklift is not moving and there is a fault in the electric forklift energy recovery system, and the fault with the highest level is higher than the preset level. When the forklift is in a stationary state, there is no braking requirement. At this time, the electric braking function can be directly turned off, and a fault prompt message is generated.

[0072] In the above case, after generating a fault prompt message, if a forklift travel instruction is received, it is determined whether the user has input a response message corresponding to the fault prompt message; if so, the forklift is controlled to move according to the forklift travel instruction; if not, the forklift travel instruction is not responded to. When the user inputs a response message, it indicates that the user already knows that braking cannot be achieved through the drive motor or the voltage proportional valve at present, and the foot brake valve can be used for braking. If no response message is received, the forklift travel instruction is not responded to to prevent safety accidents.

[0073] As a further introduction to Figure 1 the corresponding embodiment, after setting the fault with the highest level as the core fault, if the forklift is in a stationary state and the level of the core fault is lower than or equal to the preset level, a fault prompt message and a fault handling suggestion are generated.

[0074] As a feasible implementation manner, if the faults existing in the electric forklift energy recovery system are oil filter faults, battery power limit faults or motor power limit faults, it is determined that the level of the faults is lower than or equal to the preset level; if the faults existing in the electric forklift energy recovery system are pedal angle sensor faults, electro-hydraulic proportional valve faults, battery charge prohibition faults, motor zero torque faults or communication faults, it is determined that the level of the faults is higher than the preset level. Optionally, if the fault is an oil filter fault, a battery power limit fault or a motor power limit fault, the fault level is lower than or equal to the preset level; if the fault is a pedal angle sensor fault, an electro-hydraulic proportional valve fault, a battery charge prohibition fault, a motor zero torque fault or a communication fault, the fault level is higher than the preset level.

[0075] The oil filter fault refers to faults such as hydraulic oil pollution and filter element blockage in the oil filter. The battery power limit fault refers to the state of forced power limit of the battery output due to overheating, over-discharge or aging, etc. The motor power limit fault refers to the state of forced power limit of the motor output due to overload, overheating or faults. The pedal angle sensor fault refers to faults of the pedal angle sensor, such as abnormal signals, failure or deviation. The electro-hydraulic proportional valve fault refers to faults of the electro-hydraulic proportional valve, such as spool jamming, coil damage or abnormal signals. The battery charge prohibition fault refers to the fault that the battery prohibits energy recovery charging due to overheating, overcharging or protection strategies. The motor zero torque fault refers to the state where the motor is forced to output zero torque due to faults or protection strategies. The communication fault includes faults such as signal transmission interruption and delay between devices.

[0076] The following uses an embodiment in actual application to illustrate the process described in the above embodiment.

[0077] To avoid unnecessary energy consumption, kinetic energy recovery technology has emerged. For example, in related technologies, there is an electro-hydraulic composite braking system and control method for heavy-duty electric forklifts. This solution adopts the form of dual braking pedals. While retaining the original foot-operated hydraulic braking pedal, an additional recovery pedal and an electro-hydraulic proportional valve braking circuit are added. The maximum braking torque is determined according to the angle of the recovery pedal. The principle of giving priority to electric motor braking is adopted to coordinately control the braking torque of the electric motor and the hydraulic braking torque controlled by the proportional valve, so as to maximize the recovery of kinetic energy under the condition of ensuring the safe driving of the vehicle.

[0078] At present, for the kinetic energy recovery system of electric industrial vehicles or electric vehicles with power limitations on the battery and motor, kinetic energy recovery is usually directly cancelled. When a fault occurs in the hydraulic oil circuit or the drive motor, the electric braking recovery function is cancelled, and the foot valve is directly used for braking. In related technologies, battery charging is prohibited when the remaining battery power is too high, and the influence of temperature on the battery charging power is not considered, so the solution is incomplete.

[0079] At present, when a system fault occurs in an industrial vehicle equipped with a kinetic energy recovery system, such as a sensor fault or a motor fault, the kinetic energy recovery is usually directly turned off, and the motor is controlled to only allow driving or coasting, or only the foot brake valve can be used for braking.

[0080] Although the above-mentioned related technologies consider the processing solutions for faults in the kinetic energy recovery system and can ensure the safety of the system to a certain extent, there are also the following problems:

[0081] 1. The considered fault factors are not comprehensive. Only the faults of sensors, motors, and batteries are considered. However, each component in the system may have faults, and even communication interruptions may occur. Therefore, all fault points need to be comprehensively considered, and solutions should be given according to the level classification to ensure the safety of the vehicle when a fault occurs.

[0082] 2. When a fault occurs, only the restriction of prohibiting kinetic energy recovery is given. If the vehicle itself is in a stationary state, this solution can ensure the safety of the vehicle. However, if the vehicle itself is in a driving state, once a fault occurs, simply prohibiting kinetic energy recovery will cause a sense of panic of brake failure and is likely to trigger an accident. Related technologies only allow coasting to reduce speed, which will cause a sense of panic of brake failure to the driver and is likely to cause an accident; another related technology requires the driver to quickly make a judgment and step on the emergency braking mechanical pedal to reduce speed and stop, which is also likely to give the driver a sense of panic.

[0083] This embodiment adds a fault handling function, gives the fault information of each key component, classifies various faults, and adopts different handling solutions according to different levels to ensure that the braking system can smoothly switch from the normal state to the fault state when a fault occurs whether the vehicle is in a driving or stopped state, without affecting the driver's operation, and can realize the normal braking function of the vehicle.

[0084] The following uses specific embodiments to illustrate the fault handling control scheme of the braking energy recovery system for heavy-duty electric forklifts:

[0085] When the driver cancels the electric braking function, only the foot brake valve can be used for braking.

[0086] When the electric braking function is effective, if the driver steps on the electric brake pedal for kinetic energy recovery, the controller first collects the fault information of components such as the brake pedal angle sensor, electro-hydraulic proportional valve, oil filter, CAN communication, motor, and battery, and classifies them into level 1 minor faults and level 2 serious faults according to the severity of the faults. At the same time, different levels of faults are displayed on the instrument panel, and then corresponding processing is carried out according to the different severity levels of the faults.

[0087] This embodiment provides a signal acquisition and calculation module and a fault detection and classification module.

[0088] The signal acquisition and calculation module is used to collect the electric brake pedal angle signal and calculate the total target braking torque according to the brake pedal opening.

[0089] The fault detection and classification module is used to detect the fault information of components such as the pedal angle sensor, electro-hydraulic proportional valve, oil filter, CAN communication, motor, and battery, and classify the fault levels according to the severity of the faults.

[0090] This embodiment also provides the following fault handling control strategy for the electro-hydraulic composite braking system: Determine whether there is a fault in the electro-hydraulic composite braking system. If the system has no fault, determine the total target braking torque and the motor target braking torque. When the motor braking torque cannot meet the braking requirements, adjust the current value of the electro-hydraulic proportional valve for braking pressure compensation; if the system has a fault, then carry out hierarchical processing according to the different fault levels. If it is a level 2 serious fault, first obtain the driver's braking intention in real time. When the vehicle is stationary, directly cancel the electric braking, and only the foot valve braking can be performed and a prompt is given on the instrument panel. If the vehicle is moving and the fault is an angle sensor fault, the VCU gives the target braking torque according to the current vehicle speed, and after the vehicle stops stably, cancel the electric braking and only the foot valve braking can be performed. If the vehicle is moving and the fault is a proportional valve fault, the VCU first uses the motor braking to make the vehicle stop stably according to the current motor speed and then gives a fault prompt. If the vehicle is moving and the fault is a battery charge prohibition fault, motor zero torque fault, or CAN communication fault, the VCU sets the motor braking torque to 0, and all braking forces are provided by the electro-hydraulic proportional valve, and a fault prompt is given after the vehicle stops stably; if it is a level 1 minor fault, all faults only give an alarm prompt.

[0091] When a serious fault occurs in the braking system, directly canceling the electric braking function is likely to cause a sense of panic among drivers and lead to accidents. In this embodiment, a fault handling function is added, fully considering the fault information points of the electro-hydraulic composite braking system, and the fault levels are defined according to the severity of the faults. When minor faults such as filter oiler faults, battery power limit faults, or motor power limit faults occur, electric motor braking is preferred, and the insufficient part of the braking torque is controlled by a proportional valve to control the hydraulic braking torque. At the same time, all fault information and fault levels are displayed on the instrument. When serious faults such as battery charge prohibition faults, motor zero torque faults, CAN communication faults, pedal angle sensor faults, and electro-hydraulic proportional valve faults occur, if the vehicle has a serious fault in a stationary state, the electric braking is directly canceled and an alarm is given. If a fault occurs when the vehicle is moving, different control strategies are adopted according to different fault information:

[0092] (1) If there are battery charge prohibition faults, motor zero torque faults, or CAN communication faults, the electric motor braking torque is set to 0, and the remaining torque is compensated by hydraulic braking.

[0093] (2) If there is a pedal angle sensor fault, after detecting the driver's braking intention, the total target braking torque is given according to the vehicle speed, and then the electric motor braking torque and the hydraulic braking torque are determined according to the braking torque distribution strategy.

[0094] (3) If there is an electro-hydraulic proportional valve fault, the electric motor braking torque is given according to the vehicle speed after detecting the driver's braking intention.

[0095] Through the above strategies, the vehicle speed is first smoothly reduced to ensure vehicle safety, and then the electric braking function is canceled and an alarm is given.

[0096] This embodiment adopts different treatment schemes according to different fault levels to ensure that the braking system of the vehicle can smoothly switch from the normal state to the fault state when a fault occurs, whether the vehicle is moving or stationary, without affecting the driver's operation, enabling the vehicle to achieve the normal braking function and not causing a sense of panic among drivers and leading to accidents.

[0097] This embodiment comprehensively considers all the fault point information of the braking energy recovery system and divides the fault levels according to the fault point information. When minor faults such as filter oiler fault, battery power limit fault, or motor power limit occur, electric braking is preferentially used, and the proportion valve is used to control the hydraulic braking torque for the insufficient part of the braking torque. At the same time, all fault information and fault levels are displayed on the instrument. When faults such as pedal angle sensor fault, electro-hydraulic proportional valve fault, battery charging prohibition fault, motor zero torque fault, or communication fault occur, different control strategies are adopted according to different fault information. If a serious fault occurs when the vehicle is in a stopped state, the electric braking is directly cancelled and an alarm is given. If it occurs when the vehicle has a speed, the vehicle is first smoothly decelerated to ensure safety, and then the electric braking function is cancelled and an alarm is given.

[0098] Please refer to Figure 3 , Figure 3 which is a flowchart for the fault handling control of a kinetic energy recovery system provided by an embodiment of the present application, and the process includes:

[0099] Step 1: Collect the electric braking pedal angle signal and calculate the total braking torque according to the braking pedal angle.

[0100] Step 2: Perform signal detection, fault diagnosis, and fault level division, and display all faults and fault levels on the instrument.

[0101] Specifically, level 1 faults include: filter oiler fault, battery power limit fault, and motor power limit fault; level 2 faults include: pedal angle sensor fault, electro-hydraulic proportional valve fault, battery charging prohibition fault, motor zero torque fault, or communication fault.

[0102] Step 3: Determine whether there is a fault in the electric forklift energy recovery system; if not, go to Step 4; if so, go to Step 5.

[0103] Step 4: Drive the motor to run at the target torque, open the electro-hydraulic proportional valve, and calculate the proportional valve current value according to the total required braking torque and the motor target braking torque.

[0104] Step 5: Determine whether there is a level 2 fault; if not, go to Step 6; if so, go to Step 7.

[0105] Step 6: Only give an alarm prompt for the fault, drive the motor to run at the target torque; open the electro-hydraulic proportional valve and calculate the proportional valve current value according to the total required braking torque and the motor target braking torque.

[0106] Step 7: Determine the fault type and control according to the following logic:

[0107] If there is a failure of the pedal angle sensor, when the driver's braking intention is recognized, if the vehicle is stationary, the instrument will prompt that the electric braking fails and only the foot valve braking can be performed; otherwise (i.e., when the vehicle is not stationary), the VCU will give the target braking torque according to the current vehicle speed, and the fault will be prompted after the vehicle stops stably.

[0108] If there are failures such as battery charge prohibition failure, motor zero torque failure or communication failure, when the driver's braking intention is recognized, if the vehicle is stationary, the instrument will prompt that the electric braking fails and only the foot valve braking can be performed; otherwise (i.e., when the vehicle is not stationary), the VCU will set the motor braking torque to 0, and all braking forces will be provided by the electro-hydraulic proportional valve, and the fault will be prompted after the vehicle stops stably.

[0109] If there is a proportional valve failure, when the driver's braking intention is recognized, if the vehicle is stationary, the instrument will prompt that the electric braking fails and only the foot valve braking can be performed; otherwise (i.e., when the vehicle is not stationary), the VCU will first use the motor braking to make the vehicle stop stably according to the current motor speed and then prompt the fault.

[0110] This embodiment solves the problem that when key components such as batteries, motors, and angle sensors in the kinetic energy recovery system fail, the braking deceleration does not meet the design requirements, and can perform automatic state switching to avoid accidents caused by the driver's panic.

[0111] The embodiment of the present application provides a fault handling system for an electric forklift energy recovery system, which is applied to a control device of the electric forklift energy recovery system. The electric forklift energy recovery system further includes a power battery, a drive motor, a brake, an electric brake pedal, a pedal angle sensor, and an electro-hydraulic proportional valve. The pedal angle sensor is used to detect the pedal angle of the electric brake pedal, and the electro-hydraulic proportional valve is used to control the braking force of the brake by adjusting the pressure of the hydraulic oil. The fault handling system of the electric forklift energy recovery system includes:

[0112] A fault judgment module, configured to judge whether there is a fault in the electric forklift energy recovery system;

[0113] A fault analysis module, configured to determine the fault level if there is a fault in the electric forklift energy recovery system, and set the fault with the highest level as the core fault;

[0114] A first processing module, configured to, if the forklift is in a driving state and the level of the core fault is lower than or equal to a preset level, control the drive motor and / or the electro-hydraulic proportional valve to perform braking according to the pedal angle of the electric brake pedal after receiving a braking instruction;

[0115] A second processing module, configured to, if the forklift is in a driving state and the level of the core fault is higher than the preset level, after receiving a braking instruction, control the drive motor and / or the electro-hydraulic proportional valve to perform braking according to the fault type of the core fault.

[0116] Furthermore, the input end of the electro-hydraulic proportional valve is connected to an oil source, the output end of the electro-hydraulic proportional valve is connected to the input end of a shuttle valve, the output end of the shuttle valve is connected to the brake, and the brake is a wet brake.

[0117] Furthermore, it further includes a foot brake valve. The input end of the foot brake valve is connected to an oil source, the output end of the foot brake valve is connected to the input end of a shuttle valve, and the output end of the shuttle valve is connected to the brake.

[0118] Furthermore, the process in which the second processing module controls the drive motor and / or the electro-hydraulic proportional valve to perform braking according to the fault type of the core fault includes: if the fault type of the core fault is a pedal angle sensor fault, determining a target braking torque according to the current vehicle speed of the forklift, and controlling the drive motor and / or the electro-hydraulic proportional valve to perform braking according to the target braking torque; if the fault type of the core fault is an electro-hydraulic proportional valve fault, controlling the drive motor to perform braking; if the fault type of the core fault is a battery charge prohibition fault, a motor zero torque fault, or a communication fault, controlling the electro-hydraulic proportional valve to perform braking.

[0119] Furthermore, it further includes:

[0120] A prompt module, configured to, if the core fault includes an electro-hydraulic proportional valve fault and a preset fault, generate an alarm message for prompting the user to perform foot valve braking; wherein, the preset fault includes any one or a combination of any several of a battery charge prohibition fault, a motor zero torque fault, and a communication fault.

[0121] Furthermore, it further includes:

[0122] A third processing module, configured to, after setting the fault with the highest level as the core fault, if the forklift is in a stationary state and the level of the core fault is higher than the preset level, turn off the electric braking function and generate a fault prompt message; wherein, after turning off the electric braking function, the control device does not respond to the change in the pedal angle of the electric brake pedal.

[0123] Furthermore, it further includes:

[0124] The motion control module is used to, after generating a fault prompt message, if a forklift travel instruction is received, determine whether the user has input a response message corresponding to the fault prompt message; if so, control the forklift to move according to the forklift travel instruction; if not, do not respond to the forklift travel instruction.

[0125] Further, it further includes:

[0126] The third processing module is used to, after setting the fault with the highest level as the core fault, if the forklift is in a stationary state and the level of the core fault is lower than or equal to the preset level, generate a fault prompt message and a fault handling suggestion.

[0127] Further, the process of the fault analysis module determining the fault level includes: if the faults existing in the electric forklift energy recovery system are filter faults, battery power limit faults or motor power limit faults, it is determined that the level of the fault is lower than or equal to the preset level; if the faults existing in the electric forklift energy recovery system are pedal angle sensor faults, electro-hydraulic proportional valve faults, battery charging prohibition faults, motor zero torque faults or communication faults, it is determined that the level of the fault is higher than the preset level.

[0128] Since the embodiments in the system part correspond to the embodiments in the method part, for the descriptions of the embodiments in the system part, please refer to the descriptions of the embodiments in the method part, and will not be elaborated here temporarily.

[0129] This application also provides a storage medium, on which a computer program is stored, and when the computer program is executed, the steps provided by the above embodiments can be implemented. The storage medium may include: various media such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks or optical discs that can store program codes.

[0130] This application also provides an electronic device, which may include a memory and a processor. When the processor calls the computer program in the memory, the steps provided by the above embodiments can be implemented. Of course, the electronic device may also include various network interfaces, power supplies and other components.

[0131] The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section. It should be noted that for those of ordinary skill in the art, 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 present application.

[0132] 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 variation 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 elements inherent to such process, method, article or device. Without further limitation, an 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 fault handling method for an energy recovery system of an electric forklift, characterized in that, A control device applied to the energy recovery system of an electric forklift. The energy recovery system of the electric forklift further includes a power battery, a drive motor, a brake, an electric brake pedal, a pedal angle sensor, and an electro-hydraulic proportional valve. The pedal angle sensor is used to detect the pedal angle of the electric brake pedal, and the electro-hydraulic proportional valve is used to control the braking force of the brake by adjusting the pressure of the hydraulic oil. The fault handling method of the energy recovery system of the electric forklift includes: Determine whether there is a fault in the energy recovery system of the electric forklift; If so, determine the fault level, and set the fault with the highest level as the core fault; If the forklift is in a driving state and the level of the core fault is lower than or equal to the preset level, then after receiving a braking instruction, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the pedal angle of the electric brake pedal; If the forklift is in a driving state and the level of the core fault is higher than the preset level, then after receiving a braking instruction, control the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault.

2. The fault handling method of the energy recovery system of the electric forklift according to claim 1, characterized in that, Controlling the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault includes: If the fault type of the core fault is a pedal angle sensor fault, determine the target braking torque according to the current vehicle speed of the forklift, and control the drive motor and / or the electro-hydraulic proportional valve to brake according to the target braking torque; If the fault type of the core fault is an electro-hydraulic proportional valve fault, control the drive motor to brake; If the fault type of the core fault is a battery charge prohibition fault, a motor zero torque fault, or a communication fault, control the electro-hydraulic proportional valve to brake.

3. The fault handling method of the energy recovery system of the electric forklift according to claim 1, characterized in that, It further includes: If the core fault includes an electro-hydraulic proportional valve fault and a preset fault, generate an alarm message prompting the user to perform foot valve braking; wherein the preset fault includes any one or a combination of a battery charge prohibition fault, a motor zero torque fault, and a communication fault.

4. The fault handling method of the energy recovery system of the electric forklift according to claim 1, characterized in that, After setting the fault with the highest level as the core fault, it further includes: If the forklift is in a stationary state and the level of the core fault is higher than the preset level, turn off the electric braking function and generate a fault prompt message; wherein after turning off the electric braking function, the control device does not respond to the change in the pedal angle of the electric brake pedal.

5. The fault handling method of the energy recovery system of the electric forklift according to claim 4, characterized in that, After generating the fault prompt message, it further includes: If a forklift travel instruction is received, determine whether the user inputs a response message corresponding to the fault prompt message; If so, control the forklift to move according to the forklift travel instruction; If not, do not respond to the forklift travel instruction.

6. The fault handling method of the energy recovery system of the electric forklift according to claim 1, characterized in that, After setting the fault with the highest level as the core fault, it further includes: If the forklift is in a stationary state and the level of the core fault is lower than or equal to the preset level, generate a fault prompt message and a fault handling suggestion.

7. The fault handling method of the energy recovery system of the electric forklift according to claim 1, characterized in that, The determining the fault level includes: If the faults existing in the energy recovery system of the electric forklift are filter fault, battery power limit fault, or motor power limit fault, determine that the level of the fault is lower than or equal to the preset level; If the faults existing in the electric forklift energy recovery system are pedal angle sensor fault, electro-hydraulic proportional valve fault, battery charge prohibition fault, motor zero torque fault or communication fault, it is determined that the fault level is higher than the preset level.

8. A fault handling system for an energy recovery system of an electric forklift, characterized in that, A control device applied to an electric forklift energy recovery system, the electric forklift energy recovery system further including a power battery, a drive motor, a brake, an electro-hydraulic brake pedal, a pedal angle sensor and an electro-hydraulic proportional valve, the pedal angle sensor being used to detect the pedal angle of the electro-hydraulic brake pedal, the electro-hydraulic proportional valve being used to control the braking force of the brake by adjusting the pressure of the hydraulic oil, the fault processing system of the electric forklift energy recovery system including: A fault judgment module, used to judge whether there is a fault in the electric forklift energy recovery system; A fault analysis module, used to determine the fault level if there is a fault in the electric forklift energy recovery system, and set the fault with the highest level as the core fault; A first processing module, used to control the drive motor and / or the electro-hydraulic proportional valve to brake according to the pedal angle of the electro-hydraulic brake pedal after receiving a braking instruction if the forklift is in a driving state and the level of the core fault is lower than or equal to the preset level; A second processing module, used to control the drive motor and / or the electro-hydraulic proportional valve to brake according to the fault type of the core fault after receiving a braking instruction if the forklift is in a driving state and the level of the core fault is higher than the preset level.

9. The fault handling system of the energy recovery system of the electric forklift according to claim 8, characterized in that, The input end of the electro-hydraulic proportional valve is connected to an oil source, the output end of the electro-hydraulic proportional valve is connected to the input end of a shuttle valve, the output end of the shuttle valve is connected to the brake, and the brake is a wet brake.

10. The fault handling system of the energy recovery system of the electric forklift according to claim 8, characterized in that, It further includes a foot brake valve, the input end of the foot brake valve is connected to an oil source, the output end of the foot brake valve is connected to the input end of the shuttle valve, and the output end of the shuttle valve is connected to the brake.

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