Large-tonnage lithium battery forklift double-oil-pump motor control system

Abstract

The utility model relates to a double-oil-pump motor control system of a large-tonnage lithium battery forklift, and belongs to the technical field of motors. The two gear pumps are respectively arranged on the main oil pump motor and the slave oil pump motor; the hydraulic oil tank cover plate is connected with the two gear pumps; the diverter valve is connected with the gear pump of the main oil pump motor; the multi-way reversing valve is connected with the diverter valve and the gear pump of the slave oil pump motor; the brake valve and the bag type energy accumulator are connected with the three-way valve block; the controller can control the rotating speed and the working state of the main oil pump motor and the auxiliary oil pump motor so as to achieve flow distribution of the hydraulic system. The multi-way reversing valve can distribute oil liquid to different execution elements through the oil inlet and the oil outlet. For a large-tonnage lithium battery counterbalance forklift truck of 5-10 tons, on the premise that various performances such as lifting, inclining, steering and braking are guaranteed, the energy consumption, noise and cost of the whole truck are more balanced, and the use experience of a user is improved.

Description

Technical Field

[0001] This utility model belongs to the field of motor technology and relates to a dual oil pump motor control scheme for large-tonnage lithium battery forklifts, which is mainly applied to 5-10 ton lithium battery counterbalance forklifts. Background Technology

[0002] Driven by environmental concerns and lower operating costs, more and more users of traditional internal combustion forklifts are choosing electric forklifts, exhibiting the following trends: 1. The demand for electric forklifts has gradually increased from the initial 2-3 tons to 5-10 tons or even higher; 2. The battery type has shifted from lead-acid batteries to lithium batteries; 3. The vehicle voltage has gradually increased from 80V to 96 / 150 / 300V or even higher; 4. The performance requirements for electric forklifts are also increasing, especially the lifting speed, which is generally required to exceed that of internal combustion forklifts of the same tonnage.

[0003] Taking a 10-ton internal combustion forklift as an example: the lifting cylinder diameter is 100mm, the no-load lifting speed is generally 260-280mm / s, and the total displacement using a combination of a single gear pump and a double pump is about 50-55ml / r. Both gear pumps are connected to the gearbox, which is driven by the engine, and the engine's maximum speed is 2800r / min.

[0004] Taking a 10-ton 96V lithium-ion forklift as an example: the lifting cylinder diameter is 100mm, and the no-load lifting speed is generally 330-350mm / s. The high-efficiency speed range of a gear pump is generally 500-3000r / min. If a single pump motor is used for driving, the maximum corresponding pump motor speed is 3000r / min. Therefore, the gear pump's displacement must be at least 60ml / r, and the corresponding pump motor power must be at least 50kW.

[0005] However, a single 60ml / r high-displacement gear pump paired with a high-power oil pump motor of 50kW or more may cause the following problems: 1. High gear pump noise. Electric forklifts are quite sensitive to noise levels. According to relevant data, when the displacement of a single gear pump exceeds 40ml / r, the corresponding noise level will increase significantly and become difficult to control; 2. Excessive torque of the oil pump motor corresponding to the high-displacement gear pump. High torque will have a significant impact on the motor's noise, cost, and durability; 3. Large-tonnage lithium-ion forklifts generally use fully hydraulic steering and braking. Therefore, during vehicle operation, whether handling or stacking, the oil pump motor needs to be involved throughout the entire process. The corresponding high-power oil pump motor consumes a lot of electricity, generates a lot of noise, and has low efficiency when working for a long time.

[0006] For the above situations, the conventional single oil pump motor with gear pump control scheme is not the optimal choice. Utility Model Content

[0007] The purpose of this utility model is to provide a dual oil pump motor control system for large-tonnage lithium battery forklifts. For 5-10 ton large-tonnage lithium battery counterbalance forklifts, while ensuring the performance of lifting / tilting / steering / braking, the system can achieve a more balanced balance in terms of energy consumption, noise, and cost, thereby improving the user experience.

[0008] To achieve the above objectives, the present invention provides a dual-oil pump motor control system for a large-tonnage lithium-ion forklift, comprising a main oil pump motor and a slave oil pump motor, two gear pumps respectively mounted on the main oil pump motor and the slave oil pump motor, a hydraulic oil tank cover connecting the two gear pumps, a flow divider valve connecting the gear pump of the main oil pump motor, a multi-way directional valve connecting the flow divider valve and the gear pump of the slave oil pump motor, a three-way valve block connecting the flow divider valve, and a brake valve and a bladder accumulator connected to the three-way valve block; the controller can control the speed and operating status of the main oil pump motor and the slave oil pump motor to realize the flow distribution of the hydraulic system; the multi-way directional valve can distribute oil to different actuators through the oil inlet and oil outlet.

[0009] Preferably, the main oil pump motor and the slave oil pump motor can work independently or in parallel to adapt to different working modes, including non-lifting operation mode and lifting operation mode.

[0010] Preferably, in the non-lifting operation mode, the main oil pump motor adjusts its speed according to the controller command to meet the operational requirements such as idling, tilting, steering and braking; in the lifting operation mode, the main oil pump motor and the slave oil pump motor work in parallel to jointly provide the required high flow rate of oil to the lifting cylinder.

[0011] Preferably, the gear pump is connected to the hydraulic oil tank cover via a pressure-resistant rubber hose and a steel wire braided suction pipe to ensure stable operation under high flow and pressure.

[0012] Preferably, the rotational speed of the gear pump is controlled within 3000 r / min to balance the efficiency, noise and lifespan of the gear pump and ensure the long-term stable operation of the system.

[0013] Preferably, the hydraulic oil tank cover is connected to the oil suction pipe through an interface thereon, ensuring the cleanliness of the hydraulic oil and the sealing of the system, while providing a stable connection point for the oil suction pipe.

[0014] Preferably, the bladder accumulator stores high-pressure oil and provides emergency oil to the braking system in the event of a power interruption.

[0015] Preferably, the brake valve is connected to the drive axle brake via a brake steel pipe to ensure that the oil can be transmitted quickly and stably during braking.

[0016] Preferably, the steering gear receives the hydraulic fluid distributed by the multi-way directional valve and drives the steering cylinder to achieve directional control, ensuring that the vehicle's steering operation is flexible and reliable.

[0017] Preferably, the multi-way reversing valve is connected to the gear pump of the oil pump motor and the diverter valve respectively via two high-pressure hoses. The high-pressure hoses are constructed with multi-layer pressure-resistant rubber and steel wire braided layers to ensure leak-free transmission of oil under high-pressure conditions.

[0018] In summary, this utility model has the following beneficial technical effects:

[0019] This invention utilizes two 26kW oil pump motors, which can operate independently or in parallel, avoiding the high energy consumption problem associated with using a single high-power oil pump motor (50kW or more). The two smaller-power motors can flexibly adjust their operating states according to actual needs, effectively reducing energy consumption and improving the overall energy efficiency of the vehicle. Furthermore, the use of two smaller-displacement gear pumps (32ml / r) avoids the high noise problem associated with a single large-displacement gear pump (60ml / r or more). The reduced gear pump displacement allows for effective noise control, meeting the stringent low-noise requirements of electric forklifts and improving user comfort.

[0020] This invention reduces the load on key components (such as gear pumps and oil pump motors) and minimizes wear and failure risks by optimizing oil distribution and control strategies. Simultaneously, the bladder accumulator provides emergency oil backup for the braking system, enhancing system safety and reliability. The coordinated operation of the quantitative flow divider valve and the three-way valve block in this invention achieves precise oil distribution, ensuring that flow requirements are met under different operating modes (such as lifting, tilting, steering, and braking). The dual-pump parallel oil supply design provides sufficient flow in lifting operation mode, ensuring high efficiency in gantry lifting operations.

[0021] This invention improves the overall smoothness and comfort of vehicle operation by reducing the torque and noise of the oil pump motor. Simultaneously, efficient flow distribution and energy-saving design extend the vehicle's range, reduce charging frequency, and enhance the user experience. The use of a lower-power oil pump motor and a smaller displacement gear pump reduces component manufacturing and maintenance costs. Furthermore, the energy-saving design reduces energy consumption during long-term use, lowering the user's total cost of ownership. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a dual oil pump motor control system for a large-tonnage lithium-ion forklift proposed in this utility model.

[0023] Attached reference numerals: 1. Hydraulic oil tank cover; 2. Suction pipe one; 3. Gear pump one; 4. Main oil pump motor; 5. Suction pipe two; 6. Gear pump two; 7. Slave oil pump motor; 8. High-pressure hose one; 9. Steering line; 10. Multi-way directional valve; 11. High-pressure hose two; 12. Steering gear; 13. Brake steel pipe; 14. Brake valve; 15. Controller; 16. Diverter valve; 17. Bladder accumulator; 18. Three-way valve block. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] This utility model discloses a dual-pump motor control scheme for a hydraulic system. Its core lies in the coordinated control and distribution of components such as two 26kW oil pump motors (main oil pump motor 4 and slave oil pump motor 7), two 32ml / r gear pumps (gear pump one 3 and gear pump two 6), an oil pump controller, a multi-way directional valve 10, a steering gear 12, a quantitative flow divider valve (flow divider valve 16), a bladder accumulator 17, a three-way connector (three-way valve block 18), a hydraulic oil tank cover 1, and steering pipeline 9. This achieves efficient and precise hydraulic system flow distribution, meeting the performance requirements of large-tonnage lithium-ion forklifts in lifting, tilting, steering, and braking operations. By controlling the speed and operating state of two relatively small-power independent oil pump motors, the two motors can operate independently or in parallel, thereby optimizing the hydraulic system flow distribution. Simultaneously, selecting gear pumps with smaller displacement reduces the torque, noise, and cost of the motors and gear pumps, improving the overall vehicle's energy efficiency, reliability, noise reduction, and user experience.

[0026] The hydraulic oil tank cover 1, serving as the system's starting point, is installed on top of the hydraulic oil tank. It not only seals the tank but also connects to suction pipes 2 and 5 via interfaces, providing hydraulic oil inlets for gear pumps 3 and 6, respectively. The cover's structural design ensures the cleanliness of the hydraulic oil and the system's sealing, while providing a secure connection point for the suction pipes. Suction pipes 2 and 5 are both pressure-resistant rubber hoses with internal steel wire braiding layers for reinforcement, ensuring stable operation under high flow and pressure without deformation or leakage. They respectively transport hydraulic oil from the tank to gear pumps 3 and 6.

[0027] Gear pump 3 is mounted on the output shaft of the main oil pump motor 4. Through gear rotation, it pumps hydraulic oil from the suction pipe 2 to the outlet, which is connected to the diverter valve 16. The main oil pump motor 4, as one of the power sources, directly drives the rotation of gear pump 3 via its motor shaft, and adjusts its speed according to the instructions of the controller 15 to adapt to different operating modes. Gear pump 6 has the same structure as gear pump 3 and is mounted on the output shaft of the slave oil pump motor 7. Its outlet is connected to the P2 inlet of the multi-way directional valve 10 via a high-pressure hose 8, providing additional hydraulic oil flow to the lifting cylinder. The slave oil pump motor 7 also drives the rotation of gear pump 6 via its motor shaft, and adjusts its speed according to the instructions of the controller 15 to meet the high flow requirements of the lifting operation mode.

[0028] The multi-way directional valve 10 is the core control component of the system. Installed in the middle of the system, it distributes hydraulic fluid to different actuators, such as the lifting cylinder, tilting cylinder, and steering gear 12, through multiple inlets (P1, P2) and outlets. High-pressure hose 11 connects the flow divider valve 16 to the P1 inlet of the multi-way directional valve 10, ensuring leak-free fluid transmission to the multi-way directional valve 10. The steering gear 12 is responsible for steering control; by receiving the fluid distributed by the multi-way directional valve 10, it drives the steering cylinder to achieve directional control.

[0029] Brake pipe 13 connects brake valve 14 and drive axle brake, responsible for transmitting brake fluid to ensure rapid and stable fluid transmission during emergency braking. Brake valve 14 receives fluid distributed by three-way valve block 18 and controls the fluid pressure in brake pipe 13 to achieve braking function. Controller 15, as the central control unit of the system, receives sensor signals and operating commands, controls the speed and operating status of main oil pump motor 4 and slave oil pump motor 7, executes complex control algorithms, and achieves efficient and precise flow distribution.

[0030] The flow divider valve 16 is responsible for flow distribution, sending most of the flow to the P1 inlet of the multi-way directional valve 10, while simultaneously distributing a fixed amount of flow to the three-way valve block 18. The bladder accumulator 17 is responsible for storing and releasing high-pressure fluid, providing emergency fluid to the braking system in the event of a power outage to ensure safe braking of the vehicle. The three-way valve block 18 receives the fixed amount of fluid flow from the flow divider valve 16 and divides it into two paths: one path is sent to the Pa inlet of the brake valve 14, and the other path is sent to the bladder accumulator 17.

[0031] The main oil pump motor 4 and the slave oil pump motor 7 are the core power components of the hydraulic system. They execute different operating modes according to the instructions of the controller 15, covering lifting operation mode and non-lifting operation mode.

[0032] In non-lifting operation mode, the system involves various states such as idling, tilting, steering, and braking, with the main oil pump motor 4 participating throughout the operation. Taking the idling state as an example, the main oil pump motor 4 is connected to gear pump 3. After the controller 15 issues the idling command, the main oil pump motor 4 maintains a speed of 600 r / min. At this time, gear pump 3 delivers hydraulic oil to the diverter valve 16 via the hydraulic oil tank cover plate 1 and the suction pipe 2. The diverter valve 16 directs most of the flow through the high-pressure hose 11 to the P1 inlet of the multi-way directional valve 10. The multi-way directional valve 10 then distributes the flow from the P1 inlet to the steering gear 12. The outlet of the steering gear 12 is connected to the high-pressure steering line 9, which is connected to the steering cylinder, ensuring that high-pressure hydraulic fluid is always available to drive the steering cylinder during steering operations.

[0033] Meanwhile, the diverter valve 16 supplies oil to the three-way valve block 18 at a fixed flow rate of 6 L / min. The three-way valve block 18 divides the oil into two paths: one path is delivered to the Pa inlet of the brake valve 14, and the other path flows to the bladder accumulator 17. The brake valve 14 distributes hydraulic oil to the drive axle brakes through the brake steel pipe 13 to achieve the vehicle braking function. The bladder accumulator 17 receives the oil distributed by the three-way valve block 18 and stores it in a sealed cavity. Its outlet is connected to the Pb inlet of the brake valve 14. In an emergency, when power is interrupted and the gear pump cannot supply oil, the bladder accumulator 17 can release the stored high-pressure oil to the brake valve 14 to provide emergency braking protection.

[0034] The operating principle in the tilting state is similar to that in the idling state, but the speed of the main oil pump motor 4 is increased to 2400 r / min, thereby delivering more oil to the diverter valve 16. The diverter valve 16 continues to direct most of the flow to the multi-way directional valve 10, which distributes the flow to the tilting cylinder to achieve the tilting operation of the mast. The flow distribution of the steering gear 12, the metered flow distribution of the diverter valve 16, and the direction and function of the oil are all consistent with those in the idling state.

[0035] The lifting operation mode adds a lifting action to the non-lifting operation mode, resulting in a significant increase in the total system flow demand. When the lifting speed reaches 350 mm / s, the flow demand of the lifting cylinder is as high as 165 L / min. Combining the flow demands of steering, braking, and other functions, the total system flow demand needs to be at least 175 L / min. Considering factors such as gear pump efficiency, noise, and lifespan, the gear pump speed needs to be controlled below 3000 r / min. Therefore, relying solely on the main oil pump motor 4 cannot meet the system's oil circuit requirements.

[0036] In this mode, the main oil pump motor 4 remains connected to gear pump 3, while the slave oil pump motor 7 is connected to gear pump 6. When the controller 15 issues a lifting command, the main oil pump motor 4 and the slave oil pump motor 7 operate simultaneously in parallel. The speed of the main oil pump motor 4 increases to 2950 r / min. Gear pump 3 operates in the same manner as in idle mode, but with a larger output flow. The majority of the oil flows through the diverter valve 16 to the P1 inlet of the multi-way directional valve 10, and is then distributed by the multi-way directional valve 10 to the lifting cylinders to perform the gantry lifting operation. The flow distribution of the steering gear 12, the quantitative flow distribution of the diverter valve 16, and the oil flow direction and function continue the idle mode.

[0037] Meanwhile, the speed of the oil pump motor 7 also reaches 2950 r / min. The gear pump 6 pumps hydraulic oil through the hydraulic oil tank cover plate 1 and the suction pipe 5, and delivers it directly to the P2 inlet of the multi-way directional valve 10 via the high-pressure hose 8. The multi-way directional valve 10 distributes all the flow entering through the P2 port to the lifting cylinder to achieve the lifting function. Thus, the P1 and P2 ports of the multi-way directional valve 10 supply oil in parallel, and the main oil pump motor 4 and the slave oil pump motor 7 operate in parallel to meet the high flow requirements of the lifting action.

[0038] Compared to the single-pump motor and gear pump control scheme used in conventional 2-5 ton small-tonnage lithium-ion forklifts, the dual-pump motor control method of this invention significantly improves the energy efficiency and reliability of the entire vehicle, while reducing noise and cost. This not only greatly enhances the customer's user experience but also paves the way for the widespread application of large-tonnage lithium-ion forklifts. With its rational design, novel structure, practicality, and energy-saving and noise-reducing advantages, this invention effectively enhances the customer's user experience and brings an innovative solution to the field of hydraulic system control.

[0039] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A dual-oil pump motor control system for a large-tonnage lithium-ion forklift, characterized in that, The system includes a main oil pump motor (4) and a slave oil pump motor (7), two gear pumps respectively mounted on the main oil pump motor (4) and the slave oil pump motor (7), a hydraulic oil tank cover plate (1) connecting the two gear pumps, a flow divider valve (16) connecting the gear pump of the main oil pump motor (4), a multi-way directional valve (10) connecting the flow divider valve (16) and the gear pump of the slave oil pump motor (7), a three-way valve block (18) connecting the flow divider valve (16), and a brake valve (14) and a bladder accumulator (17) connecting the three-way valve block (18); the controller (15) can control the speed and working status of the main oil pump motor (4) and the slave oil pump motor (7) to realize the flow distribution of the hydraulic system; the multi-way directional valve (10) can distribute oil to different actuators through the oil inlet and oil outlet.

2. The dual oil pump motor control system for a large-tonnage lithium-ion forklift according to claim 1, characterized in that, The main oil pump motor (4) and the slave oil pump motor (7) can work independently or in parallel to adapt to different working modes, including non-lifting operation mode and lifting operation mode.

3. The dual oil pump motor control system for a large-tonnage lithium-ion forklift according to claim 2, characterized in that, In non-lifting operation mode, the main oil pump motor (4) adjusts its speed according to the instructions of the controller (15) to meet the operational requirements such as idling, tilting, steering and braking; in lifting operation mode, the main oil pump motor (4) and the slave oil pump motor (7) work in parallel to provide the required high flow rate oil to the lifting cylinder.

4. The dual oil pump motor control system for a large-tonnage lithium-ion forklift according to claim 3, characterized in that, The gear pump is connected to the hydraulic oil tank cover plate (1) via a pressure-resistant rubber hose and a steel wire braided layer reinforced suction pipe to ensure stable operation under high flow and pressure.

5. A dual-oil pump motor control system for a large-tonnage lithium-ion forklift according to claim 4, characterized in that, The speed of the gear pump is controlled within 3000 r / min to balance the efficiency, noise and lifespan of the gear pump and ensure the long-term stable operation of the system.

6. The dual oil pump motor control system for a large-tonnage lithium-ion forklift according to claim 5, characterized in that, The hydraulic oil tank cover (1) is connected to the oil suction pipe through its interface, ensuring the cleanliness of the hydraulic oil and the sealing of the system, while providing a stable connection point for the oil suction pipe.

7. A dual-oil pump motor control system for a large-tonnage lithium-ion forklift according to any one of claims 1-6, characterized in that, The bladder accumulator (17) stores high-pressure oil and provides emergency oil to the braking system in the event of a power interruption.

8. A dual-oil pump motor control system for a large-tonnage lithium-ion forklift according to any one of claims 1-6, characterized in that, The brake valve (14) is connected to the drive axle brake via the brake steel pipe (13) to ensure that the oil can be transmitted quickly and stably during braking.

9. A dual-oil pump motor control system for a large-tonnage lithium-ion forklift according to any one of claims 1-6, characterized in that, The steering gear (12) receives the oil distributed by the multi-way directional valve (10) and drives the steering cylinder to achieve directional control, ensuring that the vehicle's steering operation is flexible and reliable.

10. A dual-oil pump motor control system for a large-tonnage lithium-ion forklift according to any one of claims 1-6, characterized in that, The multi-way reversing valve (10) is connected to the gear pump of the oil pump motor (7) and the diverter valve (16) respectively through two high-pressure hoses. The high-pressure hoses are constructed with multi-layer pressure-resistant rubber and steel wire braided layers to ensure leak-free transmission of oil under high pressure conditions.

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