Oil-electric hybrid forklift driving system and control method

Abstract

The invention provides an oil-electric hybrid forklift driving system and a control method. The control method comprises the following steps that a forklift driving mode is selected based on a mode switching signal; if the oil mode is selected, the control unit controls the electromagnetic clutch to be closed, and the engine drives the walking pump to work through transmission of the motor to provide power for the driving motor; if the electric mode is selected, the control unit controls the electromagnetic clutch to be separated, the physical connection between the motor and the engine is disconnected, meanwhile, the electric power battery is controlled to supply power to the motor, and the motor drives the walking pump to work during running to provide power for the driving motor. Selection under different modes can be suitable for different application scenes, the adaptability of the forklift is improved, the working time of the forklift is prolonged, and the problems that a fuel forklift is high in energy consumption and high in emission and an electric forklift is poor in cruising ability are solved.

Description

Technical Field

[0001] The present application relates to the technical field of forklift control, and in particular to a hybrid forklift driving system and control method. Background Art

[0002] Forklifts are industrial handling equipment that are widely used in logistics, warehousing, manufacturing and other fields. However, with the increasing awareness of environmental protection and the advancement of national energy conservation and emission reduction policies, the application scope of fuel forklifts has gradually been greatly limited due to their high energy consumption and high emissions. At the same time, electric forklifts, as a substitute for fuel forklifts, have become the first choice for many companies to achieve green logistics transformation with their advantages of zero emissions, low noise and easy maintenance. However, electric forklifts also face the anxiety of endurance, which directly restricts the application of electric forklifts in special working conditions such as long-distance operations and continuous high-intensity operations. Summary of the invention

[0003] In order to solve the technical problems existing in the prior art, the first aspect of the present application provides an oil-electric hybrid forklift drive system, including an engine, an electromagnetic clutch, an electric motor, a travel pump and a drive motor, the electromagnetic clutch is connected between the engine and the electric motor, the electric motor is transmission-connected to the travel pump, and the travel pump is hydraulically transmission-connected to the drive motor; the drive system also includes a control unit and a power battery, the power battery is electrically connected to the electric motor, and the control unit is electrically connected to the electromagnetic clutch and the electric motor, respectively, for controlling the engagement and disengagement of the electromagnetic clutch, and controlling the start and stop of the electric motor.

[0004] Furthermore, the motor has a double-headed output shaft structure, the stationary disc of the electromagnetic clutch is fixed on the engine flywheel, and the moving disc of the electromagnetic clutch is fixed on the input shaft of the motor.

[0005] Furthermore, the output shaft of the electric motor is connected to the travel pump via a spline, and when the electric motor is running, the travel pump is driven to work, thereby providing power for the drive motor.

[0006] Furthermore, the hybrid forklift driving system further includes an accelerator pedal and a proportional solenoid valve, wherein the accelerator pedal is connected to the proportional solenoid valve via the control unit, and the proportional solenoid valve is connected to the travel pump.

[0007] Furthermore, the hybrid forklift driving system also includes a DC / DC converter and a lead-acid battery. The lead-acid battery is electrically connected to the power battery through the DC / DC converter, and the lead-acid battery is connected to a control unit.

[0008] Furthermore, the control unit includes a motor controller, an electric proportional controller, and an ECU controller.

[0009] A second aspect of the present application provides a driving control method for a hybrid forklift, comprising the following steps: selecting a forklift drive mode based on a mode switch signal; If the oil mode is selected, the control unit controls the electromagnetic clutch to engage, and the engine drives the travel pump through the electric motor to provide power for the drive motor; If the electric mode is selected, the control unit controls the electromagnetic clutch to disengage, disconnecting the physical connection between the motor and the engine, and at the same time controls the electric power battery to power the motor. When the motor is running, it drives the travel pump to work and provide power for the drive motor.

[0010] Furthermore, the oil mode includes the steps: the motor controller controls the motor to start, and the motor drags the engine flywheel to rotate; when the engine flywheel rotates to a preset speed, the ECU controller controls the engine to ignite and start; at the same time, the motor controller releases the control of the motor, and the motor is used to transmit the power of the engine to the travel pump.

[0011] Furthermore, the method also includes the steps of: controlling the rotation speed of the engine and / or the motor based on the position signal of the accelerator pedal; and at the same time, adjusting the oil flow of the travel pump through the proportional solenoid valve to control the speed of the entire vehicle.

[0012] Furthermore, the method also includes the steps: the motor is a double-acting motor, and when the position of the accelerator pedal returns to the initial position, the motor controller controls the motor to switch to a power generation mode, and the inertia of the entire vehicle drives the motor to generate electricity to charge the power battery.

[0013] Furthermore, the power generation mode includes: the control unit monitors the system status in real time through the temperature sensor and the voltage sensor, and when the temperature or voltage of the power battery is abnormal, controls the power battery to disconnect from the motor circuit.

[0014] Furthermore, the method also includes the steps of obtaining a signal from an emergency key switch, obtaining a signal from a start switch, and the ECU controller controlling the starter to start, thereby driving the engine to ignite and start.

[0015] Furthermore, the method also includes the steps: a speed sensor is provided on the drive motor, and when the speed of the drive motor is and the accelerator pedal is in the initial position, the control unit controls the parking switch solenoid valve to lose power to achieve automatic parking; when the accelerator pedal position moves, the control unit controls the parking switch solenoid valve to be energized to release the parking.

[0016] Compared with the prior art, the beneficial effects of this application are: The oil-electric hybrid forklift drive system and control method provided in the embodiment of the present application can flexibly switch between pure electric mode and oil mode according to working conditions. The selection under different modes can be applicable to different application scenarios, which improves the adaptability and working time of the forklift, and solves the problems of high energy consumption and high emissions of fuel forklifts and poor endurance of electric forklifts. At the same time, in the oil mode, the engine and the motor are connected by the electromagnetic clutch to achieve transmission connection. At this time, the motor drags the engine flywheel to rotate until the ignition speed is reached. This process not only shortens the start-up time of the engine, but also reduces the mechanical impact on the engine during startup.

[0017] The hybrid forklift driving system and control method provided in the embodiments of the present application control the vehicle speed by precisely controlling the rotation speed of the engine and / or the electric motor and adjusting the oil flow of the travel pump through a proportional solenoid valve, so that the vehicle can obtain appropriate power output under different working conditions, thereby improving the handling performance of the entire vehicle; at the same time, the smoothness of power transmission is ensured, which helps to reduce the vehicle's sense of frustration and improve the driving stability under complex working conditions or when driving at high speeds.

[0018] The hybrid forklift drive system provided in the embodiment of the present application also has an emergency start mode. When the lithium battery is out of power or the electric mode fails, the pure oil mode can be started through the emergency start switch, thereby improving the stability of the forklift operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of the driving control method of the hybrid forklift of the present application; Figure 2 It is a structural schematic diagram of the oil-electric hybrid forklift drive system of the present application; Figure 3 is a schematic diagram of the oil-electric hybrid forklift drive system of the present application; Figure 4 is a schematic diagram of the oil mode of the present application; Figure 5 is a schematic diagram of the electrical mode of the present application; Description of reference numerals: 1. Electric motor; 2. Engine; 3. Electromagnetic clutch; 4. Motor controller; 5. Electric proportional controller; 6. Lead-acid battery; 7. Power battery; 8. DC / DC converter; 9. Instrument; 10. Proportional solenoid valve; 11. Relay; 12. ECU controller; 13. Travel pump; 14. Drive motor; 15. Hybrid switch; 16. Accelerator pedal; 17. Start switch; 18. Stop switch; 19. Emergency key switch. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0021] refer to Figure 1 As shown, this embodiment provides a hybrid forklift driving system, including an engine 2, an electromagnetic clutch 3, an electric motor 1, a travel pump 13 and a drive motor 14. The electromagnetic clutch 3 is connected between the engine 2 and the electric motor 1, the electric motor 1 is coaxially connected to the travel pump 13, and the travel pump 13 is hydraulically connected to the drive motor 14. The driving system also includes a control unit and a power battery 7, the power battery 7 is electrically connected to the electric motor 1, and the control unit is electrically connected to the electromagnetic clutch 3 and the electric motor 1, respectively, for controlling the electromagnetic clutch 3 to engage and disengage, and controlling the start and stop of the electric motor 1.

[0022] In some embodiments, the control unit includes a motor controller 4, an electric proportional controller 5, and an ECU controller 12, the motor controller 4 is connected to the electromagnetic clutch 3 and the motor 1 respectively, and the ECU controller 12 is connected to the engine 2 and the starter respectively.

[0023] In some embodiments, the motor 1 is a double-headed output shaft structure, the stationary disc of the electromagnetic clutch 3 is fixed on the flywheel of the engine 2, and the moving disc of the electromagnetic clutch 3 is fixed on the input shaft of the motor 1. The motor 1 and the engine 2 are electrically attracted by the electromagnetic clutch 3 to achieve transmission connection. The output shaft of the motor 1 is connected to the travel pump 13 through a spline. When the motor 1 is running, it drives the travel pump 13 to work and provide power for the drive motor 14. The drive motor 14 receives the oil pressure from the travel pump 13 to drive the vehicle to travel.

[0024] This embodiment can flexibly switch between oil mode and electric mode according to working conditions through the engagement and separation of the electromagnetic clutch 3. In oil mode, the engine 2 drives the travel pump 13 through the transmission of the motor 1 to provide power for the drive motor 14; in electric mode, it completely relies on the motor 1 to reduce fuel consumption and emissions. Solve the problems of high energy consumption and high emissions of fuel forklifts and the problem of poor endurance of electric forklifts.

[0025] In some embodiments, the hybrid forklift driving system further includes an accelerator pedal 16 and a proportional solenoid valve 10. The accelerator pedal 16 is connected to the proportional solenoid valve 10 through an electric proportional controller 5. The proportional solenoid valve 10 is connected to a travel pump 13 to control the flow rate of hydraulic oil output by the hydraulic system to the travel pump 13. At the same time, the accelerator pedal 16 is connected to the motor controller 4 and the ECU controller 12, respectively.

[0026] The accelerator pedal 16 is a direct input device for the driver's intention. Its position change is converted into an electrical signal through a sensor and transmitted to the control unit. The control unit controls the speed of the engine 2 and / or the motor 1. At the same time, the electric proportional controller 5 receives the electrical signal of the accelerator pedal 16 and sends a control signal to the proportional solenoid valve 10. After receiving the control signal, the proportional solenoid valve 10 adjusts the oil flow according to the signal strength, and then controls the operation of the travel pump 13 and the drive motor 14, thereby controlling the speed of the vehicle. By accurately controlling the speed of the engine 2 and / or the motor 1, the vehicle can obtain appropriate power output under different working conditions, thereby improving the handling performance of the vehicle. At the same time, the proportional solenoid valve 10 adjusts the oil flow according to the signal of the accelerator pedal 16, thereby controlling the operation of the travel pump 13 and the drive motor 14, ensuring the stability of power transmission, which helps to reduce the frustration of the vehicle and improve the driving stability under complex working conditions or high-speed driving.

[0027] In some embodiments, the hybrid forklift drive system also includes a DC / DC converter 8 and a lead-acid battery 6. The lead-acid battery 6 is electrically connected to the power battery 7 through the DC / DC converter 8. At the same time, the lead-acid battery 6 is respectively connected to the motor controller 4, the electric proportional controller 5, the ECU controller 12, the instrument 9, the hybrid switch 15, the accelerator pedal 16, the start switch 17, the stop switch 18, and the emergency key switch 19 to provide power energy for the motor controller 4, the electric proportional controller 5, the instrument 9 and the ECU controller 12.

[0028] The present application also provides a driving control method for a hybrid forklift, comprising the following steps: Step S101, selecting a forklift driving mode based on a mode switch signal 15; Step S102: If the oil mode is selected, the control unit controls the electromagnetic clutch 3 to engage, and the engine 2 drives the travel pump 13 to work through the electric motor 1 to provide power for the drive motor 14; Step S103, if the electric mode is selected, the control unit controls the electromagnetic clutch 3 to disengage, disconnecting the physical connection between the motor 1 and the engine 2, and at the same time controls the electric power battery 7 to supply power to the motor 1. When the motor 1 is running, it drives the travel pump 13 to work and provide power for the drive motor 14.

[0029] In oil mode, the driver selects oil mode through the hybrid switch 15. After receiving the selection signal of the hybrid switch 15, the motor controller 4 controls the electromagnetic clutch 3 to engage, so that the double-acting motor 1 is physically connected to the engine 2. At the same time, the motor controller 4 controls the motor 1 to start, and the motor 1 uses its high torque characteristics to drag the flywheel of the engine 2 to rotate. When the flywheel of the engine 2 rotates to the preset speed, the ECU controller 12 controls the engine 2 to ignite and start; after the engine 2 ignites successfully, the motor controller 4 releases the control of the motor 1, and the engine 2 drives the motor 1 to rotate through the electromagnetic clutch 3. The motor 1 is used to transmit the power of the engine 2 to the travel pump 13. This process not only shortens the start-up time of the engine, but also reduces the mechanical impact on the engine during startup, thereby improving the service life of the engine and driving comfort.

[0030] In the electric mode, the hybrid switch 15 selects the electric mode, and the motor controller 4 controls the electromagnetic clutch 3 to separate after receiving the selection signal sent by the hybrid switch 15, thereby disconnecting the motor 1 from the engine 2. At the same time, the motor controller 4 controls the power battery 7 to be connected to the circuit of the motor 1, and the power battery 7 provides a power source for the motor controller 4. The motor controller 4 controls the motor 1 to start and maintain the idle speed. At the same time, the power battery 7 converts high voltage electricity into 24V electricity through a DC / DC converter, supplies low voltage electricity to the whole vehicle, and charges the lead-acid battery 6.

[0031] In some embodiments, the method further comprises the steps of: Step S104: Based on the position signal of the accelerator pedal 16, the rotation speed of the engine 2 and / or the motor 1 is controlled; at the same time, the oil flow of the travel pump 13 is adjusted through the proportional solenoid valve 10, so as to control the speed of the whole vehicle.

[0032] Specifically, in the oil mode, the driver first sends a forward / reverse signal to the electric proportional controller 5 through the gear switch, and then controls the movement of the accelerator pedal 16. The position change of the accelerator pedal 16 is converted into an electrical signal through the sensor and transmitted to the ECU controller 12 and the electric proportional controller 5 through the CAN bus. The ECU controller 12 receives the electrical signal from the accelerator pedal 16 to control the operating speed of the engine 2; the electric proportional controller 5 receives the electrical signal from the accelerator pedal 16 and adjusts the opening of the proportional solenoid valve 10 to adjust the oil flow, thereby controlling the operation of the travel pump 13 and the drive motor 14, and then controlling the vehicle speed.

[0033] In electric mode, the driver first sends a forward / reverse signal to the motor controller 4 and the electric proportional controller 5 through the gear switch, and then controls the movement of the accelerator pedal 16. The position change of the accelerator pedal 16 is converted into an electrical signal through the sensor and transmitted to the motor controller 4 and the electric proportional controller 5 through the CAN bus. The motor controller 4 controls the running speed of the motor 1 after receiving the electrical position signal from the accelerator pedal 16; the proportional controller 5 adjusts the opening of the proportional solenoid valve 10 after receiving the electrical signal from the accelerator pedal 16 to adjust the oil flow and thus control the vehicle speed.

[0034] In some embodiments, the motor 1 is a double-acting motor. When the driver releases the accelerator pedal 16, it is first detected by the sensor of the accelerator pedal 16, and the signal is transmitted to the motor controller 4 and the electric proportional controller 5 through the CAN bus. The motor controller 4 controls the motor 1 to change to the generator mode, and the inertia of the whole vehicle drives the motor 1 to rotate through the travel pump 13. The motor 1 converts mechanical energy into electrical energy, and the electrical energy is transmitted to the power battery 7 through the motor controller 4 to charge the power battery 7.

[0035] In some embodiments, during the energy recovery process, the motor controller 4 and the ECU controller 12 monitor the system status in real time through the temperature sensor and the voltage sensor to ensure the efficiency and safety of energy recovery. When the temperature of the power battery 7 exceeds the predetermined temperature or the voltage is abnormal, the motor controller 4 controls the power battery 7 to disconnect from the circuit of the motor 1 to prevent damage to the equipment.

[0036] In some embodiments, the emergency key switch 19 is turned on, and the ECU controller 12 switches the accelerator pedal 16 signal of the motor controller 4 to the ECU controller 12 through the relay 11; the start switch 17 is pressed, and the starter on the engine 2 is started, driving the engine 2 to ignite; the whole vehicle controls the operation of the engine 2 through the ECU controller 12. When the lithium battery is out of power or the electric mode fails, the emergency start switch can be used to start the oil mode, which improves the stability of the forklift operation.

[0037] In some embodiments, a speed sensor is provided on the drive motor 14, and the speed sensor transmits the speed signal of the drive motor 14 to the electric proportional controller 5. When the speed of the drive motor 14 is 0 and the accelerator pedal 16 is in the initial position, the electric proportional controller 5 controls the parking switch solenoid valve to lose power to achieve automatic parking; when the position of the accelerator pedal 16 moves, the electric proportional controller 5 obtains the movement signal of the accelerator pedal 16 through the CAN bus, and the electric proportional controller 5 controls the parking switch solenoid valve to be energized to release the parking.

[0038] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present application. Without departing from the spirit and scope of the present application, the present application may have various changes and improvements, which fall within the scope of the present application to be protected. The scope of protection claimed in the present application is defined by the attached claims and their equivalents.

Claims

1. A hybrid forklift drive system, characterized in that: The invention comprises an engine (2), an electromagnetic clutch (3), an electric motor (1), a travel pump (13) and a drive motor (14), wherein the electromagnetic clutch (3) is connected between the engine (2) and the electric motor (1), the electric motor (1) is transmission-connected to the travel pump (13), and the travel pump (13) is hydraulically transmission-connected to the drive motor (14); the drive system further comprises a control unit and a power battery (7), wherein the power battery (7) is electrically connected to the electric motor (1), and the control unit is electrically connected to the electromagnetic clutch (3) and the electric motor (1) respectively, and is used for controlling the engagement and disengagement of the electromagnetic clutch (3), and controlling the start and stop of the electric motor (1).

2. The hybrid forklift driving system according to claim 1, characterized in that: The motor (1) is a double-headed output shaft structure, the stationary disc of the electromagnetic clutch (3) is fixed on the flywheel of the engine (2), and the moving disc of the electromagnetic clutch (3) is fixed on the input shaft of the motor (1).

3. The hybrid forklift driving system according to claim 1, characterized in that: The output shaft of the electric motor (1) is connected to the travel pump (13) via a spline, and when the electric motor (1) is in operation, it drives the travel pump (13) to work, thereby providing power for the drive motor (14).

4. The hybrid forklift driving system according to claim 1, characterized in that: The hybrid forklift driving system further comprises an accelerator pedal (16) and a proportional solenoid valve (10); the accelerator pedal (16) is connected to the proportional solenoid valve (10) via the control unit; and the proportional solenoid valve (10) is connected to the travel pump (13).

5. The hybrid forklift driving system according to claim 1, characterized in that: The hybrid forklift driving system further comprises a DC / DC converter (8) and a lead-acid battery (6); the lead-acid battery (6) is electrically connected to the power battery (7) via the DC / DC converter (8), and the lead-acid battery (6) is connected to a control unit.

6. The hybrid forklift driving system according to any one of claims 1 to 5, characterized in that: The control unit comprises a motor controller (4), an electric proportional controller (5), and an ECU controller (12).

7. A driving control method for a hybrid forklift, characterized in that: The following steps are involved: Selecting a forklift driving mode based on a mode switch signal (15); If the oil mode is selected, the control unit controls the electromagnetic clutch (3) to engage, and the engine (2) drives the travel pump (13) to work through the electric motor (1), thereby providing power for the drive motor (14); If the electric mode is selected, the control unit controls the electromagnetic clutch (3) to disengage, disconnecting the physical connection between the electric motor (1) and the engine (2), and at the same time controls the electric power battery (7) to supply power to the electric motor (1). When the electric motor (1) is running, it drives the travel pump (13) to work, providing power for the drive motor (14).

8. The driving control method of a hybrid forklift according to claim 7, characterized in that: The oil mode comprises the following steps: the motor controller (4) controls the motor (1) to start, and the motor (1) drives the flywheel of the engine (2) to rotate; when the flywheel of the engine (2) rotates to a preset speed, the ECU controller (12) controls the engine (2) to ignite and start; at the same time, the motor controller (4) releases the control of the motor (1), and the motor (1) is used to transmit the power of the engine (2) to the travel pump (13).

9. The driving control method of a hybrid forklift according to claim 7, characterized in that: The method further comprises the steps of: controlling the rotation speed of the engine (2) and / or the electric motor (1) based on the position signal of the accelerator pedal (16); and at the same time, adjusting the oil flow of the travel pump (13) through the proportional solenoid valve (10), thereby controlling the speed of the entire vehicle.

10. The driving control method of a hybrid forklift according to claim 9, characterized in that: The method further comprises the following steps: the motor (1) is a double-acting motor, and when the position of the accelerator pedal (16) is restored to the initial position, the motor controller (4) controls the motor (1) to switch to a power generation mode, and the inertia of the entire vehicle drives the motor (1) to generate electricity to charge the power battery (7).

11. The driving control method of a hybrid forklift according to claim 10, characterized in that: The power generation mode includes: the control unit monitors the system status in real time through a temperature sensor and a voltage sensor, and when the temperature or voltage of the power battery (7) is abnormal, controls the power battery (7) to disconnect the circuit from the motor (1).

12. The driving control method of a hybrid forklift according to claim 7, characterized in that: The method further comprises the steps of obtaining a signal from an emergency key switch (19), obtaining a signal from a start switch (17), and the ECU controller (12) controlling the starter to start, thereby driving the engine (2) to ignite and start.

13. The driving control method of a hybrid forklift according to claim 7, characterized in that: The method further comprises the steps of: a speed sensor is provided on the drive motor (14); when the speed of the drive motor (14) is 0 and the accelerator pedal (16) is in the initial position, the control unit controls the parking switch solenoid valve to lose power, thereby realizing automatic parking; and when the position of the accelerator pedal (16) moves, the control unit controls the parking switch solenoid valve to be energized, thereby releasing the parking.

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