Proportional lifting power unit special for AGV

Abstract

The invention discloses a proportional lifting power unit special for an AGV, relates to the technical field of logistics equipment, and aims to solve the problems that the lifting speed of an existing AGV lifting power unit is affected by loads, proportional adjustment cannot be achieved, the motor efficiency is low, and the maintenance cost is high. The power unit comprises an integrated direct current brushless motor, a central valve block, an external meshing helical gear pump, a proportional amplification type electromagnetic coil and an electric proportional valve; the integrated direct-current brushless motor realizes a fixed rotating speed through frequency regulation and control and is matched with the gear pump to stably supply oil, so that the lifting speed is not influenced by load and can be proportionally regulated; the electric proportional valve integrates a proportional amplifier and an electromagnetic coil, the structure is simplified, and maintenance cost is reduced. The control precision and the safety coefficient of the AGV lifting module are improved, energy consumption and noise (smaller than or equal to 68 dB) are reduced, the service life of the motor is prolonged, and the AGV lifting module is suitable for intelligent logistics and unmanned warehouse scenes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of logistics equipment, in particular to a proportional lifting power unit special for AGV (Automatic Guided Vehicle), which is used to realize proportional lifting control of AGV carrier fork and adapt to operation requirements of intelligent logistics and unmanned warehouse. BACKGROUND

[0002] At present, the lifting function of AGV carrier in the market mainly depends on the power unit driven by DC brush motor, and its working principle is that the motor drives the gear pump to pump oil, and the single-acting oil cylinder is controlled to rise through oil pressure, and the rising speed of the oil cylinder is determined by the rotating speed of the motor. However, the existing technology has the following significant defects: 1. Poor speed stability and no proportional adjustment: the rotating speed of the DC brush motor is easily affected by load changes, resulting in inconsistent rising speed when AGV carries different weights; if the lifting speed needs to be reduced, the motor voltage needs to be reduced to 50% of the rated voltage, only two speed levels of "fast" and "slow" can be achieved, and proportional adjustment required by fine operation cannot be met.

[0003] 2. Limited motor performance and service life: under the condition of under-voltage, the mechanical efficiency of the DC brush motor is significantly reduced, the heat is serious, the load capacity is reduced, and the operating noise is increased, which directly shortens the service life of the motor.

[0004] 3. High maintenance cost: the power unit of the traditional AGV controls the oil return section of the proportional valve through the amplifier module integrated in the controller to control the descending speed of the fork; and the controller also considers the control of the walking motor, steering and other functions, so that the amplifier module is highly integrated, and when the amplifier module fails, the replacement or maintenance cost of the controller is extremely high. SUMMARY

[0005] To solve the above problems, the present application aims to provide a proportional lifting power unit special for AGV, which realizes that the lifting speed in the AGV load range is not affected by the weight, the lifting and descending speed is proportionally adjusted, the energy consumption and noise are reduced (the overall noise is ≤68dB), the safety factor and service life are improved, and the manufacturing and maintenance costs are reduced by adopting an integrated DC brushless motor (including an end cover controller and a permanent magnet brushless motor), a gear pump with external meshing helical teeth design, and a digital proportional amplifier integrated electric proportional valve.

[0006] To achieve the above purpose, the technical scheme of the present application is as follows: The application discloses a proportional lifting power unit special for AGV, which comprises an integrated DC brushless motor, a center valve block, a gear pump, an overflow valve, a one-way valve, a proportional amplification type electromagnetic coil and an electric proportional valve; the integrated DC brushless motor is composed of an end cover controller and a permanent magnet brushless motor, the end cover controller is internally provided with an inverter module, which is used for inverting DC power of a vehicle-mounted battery into AC power to drive the permanent magnet brushless motor, and the rotating speed of the permanent magnet brushless motor is controlled by the frequency of the input AC power of the end cover controller; the gear pump and the integrated DC brushless motor are both fixed on the center valve block; the overflow valve, the one-way valve and the electric proportional valve are all integrated in the center valve block, the overflow valve is used for pressure relief when the oil pressure in the center valve block exceeds a preset value, and the one-way valve only allows oil to flow from the gear pump side to the oil cylinder side; the electric proportional valve and the proportional amplification type electromagnetic coil are integrally arranged, the proportional amplification type electromagnetic coil can receive a displacement sensor signal and output different currents to control the opening and closing degree of the valve core of the electric proportional valve.

[0007] Further, the integrated DC brushless motor is provided with a first displacement sensor, the first displacement sensor is installed on an AGV whole vehicle control panel, and is used for adjusting the frequency of the AC power output by the end cover controller, so as to control the rotating speed of the permanent magnet brushless motor.

[0008] Further, the electric proportional valve is provided with a second displacement sensor, the second displacement sensor is installed on the AGV whole vehicle control panel, and is used for adjusting the output current of the proportional amplification type electromagnetic coil, so as to control the displacement of the valve core of the electric proportional valve.

[0009] Further, the center valve block is provided with a P port, a T1 port and a T2 port; the P port is used for connecting an oil cylinder oil inlet, and is used for outputting oil when lifting; the T1 port is used for connecting an oil tank, and is used for returning oil when the overflow valve is relieved; and the T2 port is used for connecting the oil tank, and is used for returning oil when descending.

[0010] Further, the rear end cover of the gear pump is provided with an oil inlet, and the front end cover is provided with an oil outlet, oil is sucked in through the oil inlet of the rear end cover and is pumped into the center valve block from the oil outlet of the front end cover.

[0011] Further, the valve core of the electric proportional valve is completely closed in the lifting state, and the opening and closing degree of the valve core is adjusted according to the current size of the proportional amplification type electromagnetic coil in the descending state.

[0012] Further, the gear pump adopts an external meshing helical tooth design and is drivingly connected with the integrated DC brushless motor through a shaft coupling.

[0013] Further, the overflow valve and the electric proportional valve are respectively provided with a first screw plug and a second screw plug.

[0014] Beneficial effects: Stable and proportionally adjustable lifting speed: The rotating speed of the integrated direct-current brushless motor is controlled by the frequency of alternating current, which is independent of the load, ensuring the constant lifting speed of the AGV within the load range; the motor frequency can be adjusted by the first displacement transducer, enabling continuous proportional adjustment of the lifting speed and meeting the needs of fine operation.

[0015] Excellent motor performance and long service life: The direct-current brushless motor has a brushless structure, low operating noise and low heat generation, with a mechanical efficiency 20%-30% higher than that of traditional brush motors, prolonged continuous working time and significantly increased service life, reducing the cost of motor replacement and maintenance.

[0016] Simplified structure and low maintenance cost: The proportional amplifier is integrated on the electromagnetic coil of the electric proportional valve, eliminating the connection harness between the amplifier and the coil in the traditional controller, making the structure more compact; when the amplifier module fails, only the proportional valve assembly needs to be repaired or replaced, without the need to replace the entire controller, reducing the maintenance cost by 40%-60%.

[0017] Low energy consumption and low noise: The external engagement helical gear pump is matched with the brushless motor, and the overall noise of the power unit is controlled below 68dB, which is much lower than that of the traditional AGV power unit (above 80dB); the brushless motor operates at rated power, reducing energy consumption by 15%-25% compared with traditional brush motors.

[0018] High safety factor: The overflow valve prevents hydraulic system overpressure damage, and the one-way valve prevents accidental lowering of the forks, improving the operation safety of the AGV lifting module. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which form a part of this application, are used to provide a further understanding of the application, and the illustrative embodiments thereof, mutually explain the application, and do not constitute an improper limitation of the application. In the drawings: Figure 1 Structure schematic view of the AGV-specific proportional lifting power unit described in the embodiments of the application; Figure 2 Lifting state oil path diagram of the AGV-specific proportional lifting power unit described in the embodiments of the application; Figure 3 Lowering state oil path diagram of the AGV-specific proportional lifting power unit described in the embodiments of the application; Figure 4 Working principle diagram of the proportional amplifier type electromagnetic coil of the AGV-specific proportional lifting power unit described in the embodiments of the application; Figure 5 Hydraulic principle diagram of the AGV-specific proportional lifting power unit described in the embodiments of the application. DETAILED DESCRIPTION

[0020] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict.

[0021] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0022] Embodiment 1 Reference Figures 1-5 : A proportional lifting power unit special for AGV, comprising an integrated DC brushless motor 1, a center valve block 2, a gear pump 3, an overflow valve 6, a one-way valve 7, a proportional amplification type electromagnetic coil 8 and an electric proportional valve 9; the integrated DC brushless motor 1 is composed of an end cap controller and a permanent magnet brushless motor, the end cap controller is internally provided with an inverter module, which is used for inverting DC power of a vehicle-mounted battery into AC power to drive the permanent magnet brushless motor, and the rotating speed of the permanent magnet brushless motor is controlled by the frequency of the input AC power; the gear pump 3 and the integrated DC brushless motor 1 are both fixed on the center valve block 2; the overflow valve 6, the one-way valve 7 and the electric proportional valve 9 are all integrated in the center valve block 2, the overflow valve 6 is used for pressure relief when the oil pressure in the center valve block 2 exceeds a preset value, and the one-way valve 7 only allows oil to flow from the gear pump 3 side to the oil cylinder side; the electric proportional valve 9 and the proportional amplification type electromagnetic coil 8 are integrally arranged, the proportional amplification type electromagnetic coil 8 can receive a displacement sensor signal and output different currents to control the opening and closing degree of the valve core of the electric proportional valve 9.

[0023] In this embodiment, the integrated DC brushless motor (end cap controller + permanent magnet brushless motor, rotating speed controlled by AC frequency) is used, in the rated power range, the rotating speed of the motor is only determined by the frequency, and is irrelevant to the load, the oil output of the gear pump is stably outputted with the rotating speed of the motor, and finally the lifting speed is constant in the load range of the AGV, the defects of the traditional DC brush motor that the rotating speed fluctuates with the load are solved, and the lifting control precision is improved.

[0024] The DC brushless motor has no carbon brush wear, higher mechanical efficiency and less heat, which not only reduces energy consumption, but also avoids the problems of heat generation due to under-voltage and short service life of the traditional brush motor, and prolongs the overall service life of the power unit.

[0025] The overflow valve is arranged to relieve pressure when the oil pressure in the center valve block exceeds a preset value, to prevent damage to the hydraulic components due to high pressure, and to avoid over-power operation of the motor to protect the motor; the one-way valve only allows oil to flow to the oil cylinder in one direction, to prevent the oil from flowing back in the opposite direction during lifting, causing the fork to accidentally drop, and to double-protect to improve the safety factor of the lifting operation of the AGV.

[0026] The electric proportional valve and the proportional amplification type electromagnetic coil are integrally arranged, the connecting wire harness between the amplifier and the coil in the traditional AGV controller is omitted, and the structure is more compact; during subsequent maintenance, the highly integrated controller does not need to be disassembled, only the proportional valve assembly needs to be repaired, the high cost problem of overall replacement of the traditional controller is avoided, and the maintenance cost is reduced.

[0027] In a specific example, the integrated direct-current brushless motor 1 is provided with a first variator, which is installed on the AGV vehicle control panel and used to adjust the frequency of the AC power output by the end cover controller, thereby controlling the speed of the permanent magnet brushless motor.

[0028] The first variator of the embodiment is directly related to motor frequency adjustment. The operator can continuously change the frequency of the AC power by rotating the variator knob on the control panel, thereby continuously controlling the motor speed and the oil volume of the gear pump, and finally achieving "proportional regulation" of the lifting speed, rather than the traditional "fast / slow" two fixed adjustments of the brush motor, which can adapt to the fine needs of lifting speed in different operating scenarios (such as fast lifting under light load and stable lifting under heavy load). The variator is integrated into the vehicle control panel, which conforms to the regular operating habits of AGV operators and does not require additional complex adjustment components. The operation is intuitive and convenient, reducing the learning cost of operators and improving the overall operation experience of AGV.

[0029] In a specific example, the electric proportional valve 9 is provided with a second variator, which is installed on the AGV vehicle control panel and used to adjust the output current of the proportional amplification type electromagnetic coil 8, thereby controlling the displacement of the valve core of the electric proportional valve 9.

[0030] The second variator can continuously change the opening degree of the electric proportional valve core by adjusting the electromagnetic coil current, thereby continuously controlling the oil return speed and achieving "proportional regulation" of the fork lowering speed (such as slow descent of precision goods and rapid descent of ordinary goods), avoiding the problems of goods knocking or low efficiency caused by traditional fixed lowering speed, and ensuring the safety and efficiency of the unloading process.

[0031] The second variator and the first variator are both installed on the vehicle control panel, and the operator can control the lifting and lowering speed through the same type of knob, which has consistent operation logic and does not require adaptation to different adjustment methods, further reducing the operation difficulty and improving the operation efficiency.

[0032] In a specific example, the center valve block 2 is provided with P port, T1 port and T2 port; the P port is used to connect the oil cylinder inlet, and the oil liquid is output during lifting; the T1 port is used to connect the oil tank, and the oil liquid is returned when the relief valve 6 is relieved; the T2 port is used to connect the oil tank, and the oil liquid is returned during descent.

[0033] The oil ports (inlet, overflow return oil, and descent return oil) of different functions in the embodiment are clearly distinguished on the center valve block, and the oil flow path is independent and clear. If there is a problem such as oil leakage or poor return flow in the future, the problem area can be quickly located (such as T1 port return oil anomaly for troubleshooting overflow valve, and T2 port return oil anomaly for troubleshooting proportional valve), reducing the time cost of troubleshooting and maintenance.

[0034] Independent oil return ports (T1 port, T2 port) can avoid the mixing of overflow pressure relief oil and descending backflow oil in the center valve block, prevent pressure fluctuations caused by oil disturbance, ensure stable hydraulic system pressure, further improve the stability of the lifting and descending process, and reduce the impact of pressure fluctuations on oil cylinders, motors and other components.

[0035] In a specific example, the rear end cover of the gear pump 3 is provided with an oil inlet, and the front end cover is provided with an oil outlet. The oil is sucked in through the oil inlet of the rear end cover and pumped into the center valve block 2 from the oil outlet of the front end cover.

[0036] The rear end cover of the gear pump is close to the motor side, and the front end cover is close to the oil passage of the center valve block. The oil inlet is provided on the rear end cover, and the oil outlet is provided on the front end cover. This can shorten the flow path of the oil between the gear pump and the center valve block, reduce the flow resistance of the oil, improve the oil supply response speed (such as after the motor starts, the oil can quickly enter the center valve block to push the oil cylinder to lift), and avoid the problem of lifting delay caused by too long path.

[0037] This oil port layout can make the connection of the gear pump and the center valve block more compact (the oil outlet directly connects the oil passage of the center valve block), without the need for additional elbow or extended oil pipe, further simplifying the overall structure of the power unit, reducing the risk of oil pipe leakage, and reducing the volume and weight of the power unit, which is suitable for the limited installation space of AGV.

[0038] In a specific example, the electric proportional valve 9 is fully closed when lifting, and the valve core adjusts the opening degree according to the current size of the proportional amplification type electromagnetic coil 8 when descending.

[0039] When lifting, the electric proportional valve core is fully closed, which can avoid oil leakage from the proportional valve, ensure that all the oil output by the gear pump enters the oil cylinder through the P port, maximize the use of oil pressure to push the oil cylinder to lift, avoid the problem of insufficient lifting force or reduced lifting speed caused by leakage, and ensure the reliability of the lifting process.

[0040] When descending, the valve core only controls the opening degree by the current of the proportional amplification type electromagnetic coil, excluding other factors (such as lifting oil pressure) that interfere with the descending speed, ensuring that the descending speed adjustment only depends on the operation of the second displacement sensor, further improving the adjustment accuracy of the descending speed, and adapting to scenes with high unloading precision requirements (such as electronic components and precision instrument handling).

[0041] In a specific example, the gear pump 3 adopts an external meshing helical tooth design and is connected in transmission with the integrated direct current brushless motor 1 through a shaft coupling 4.

[0042] The gear pump of the present embodiment adopts an external meshing helical tooth design, which has more stable tooth surface contact and significantly reduced noise compared with traditional spur gear pumps.

[0043] In a specific example, the overflow valve 6 and the electric proportional valve 9 are respectively provided with first and second threaded plugs 5 and 10.

[0044] The first and second threaded plugs of the embodiment are M8*1 plugs and M14*1.5 plugs, respectively, which guarantee the sealing performance of the hydraulic system and improve safety through the threaded plugs.

[0045] The lifting process of the embodiment is as follows: No. 1 is an integrated direct-current brushless motor, which is composed of two parts, i.e. a controller of an end cover part and a permanent magnet brushless motor of a main body part. The controller of the end cover part converts direct current of a vehicle-mounted battery into alternating current through an inverter module inside the controller to drive the permanent magnet brushless motor. Within a rated power range, the speed of the brushless motor is controlled only by the frequency of the input alternating current of the controller. The output frequency inside the motor controller can be adjusted by rotating a variable resistor knob on a control panel of the whole vehicle. When the variable resistor is rotated from 0 to a fixed position, the motor operates at a fixed speed. The motor 1 and the gear pump 3 are fixed on the center valve block 2. The gear pump 2 adopts an external meshing helical tooth design, which is lower in noise than an external meshing straight tooth design. The motor 1 drives the gear pump 3 through a driving coupling 4 to supply oil. The oil enters the gear pump from the rear end cover inlet of the gear pump 3, and is pumped into the center valve block from the front end cover outlet. The oil flows out from the P port of the center valve block 2 through a one-way valve, thereby pushing the oil cylinder to complete the lifting action. When the oil pressure inside the center valve 2 exceeds the factory set value of the overflow valve 6, the overflow valve 6 will be relieved of pressure. The presence of the overflow valve 6 ensures that the hydraulic system will not be damaged by excessive pressure, and that the motor 1 will not be damaged by over-power operation due to excessive pressure.

[0046] The lowering process is as follows: During the lifting process, the valve core inside the electric proportional valve 9 is in a completely closed state, and the oil cannot pass through the proportional valve. The proportional valve integrates a digital proportional amplifier, an electromagnetic coil and a flow valve. By adjusting another variable resistor on the AGV control panel, the digital proportional amplifier outputs different current values. When the current value is larger, the magnetic field force generated by the electromagnetic coil is larger, and the displacement of the valve core inside the flow valve due to the attractive force is larger, so the opening degree is larger, and the flow is larger. When the AGV carrier prepares to unload, the motor does not operate. By rotating the variable resistor knob, the proportional valve core is opened, and the oil inside the oil cylinder is returned to the center valve block 2 through the oil pipe under the action of the load gravity of the forks. The return flow rate is affected by the return oil cross-sectional area at the electric proportional valve 9, thereby controlling the lowering speed of the forks. The control principle of the lowering process is consistent with that of the traditional AGV lifting power unit, but the improvement lies in integrating the amplifier module into the electromagnetic coil of the proportional valve, which eliminates the connection harness between the amplifier and the coil, is smaller in size, simpler in structure, more convenient in maintenance and higher in economic value.

[0047] As Figure 2 shown: when the motor 1 through the shaft coupling 4 drive gear pump 3 operation, the oil through the gear pump inlet S is sucked into the gear pump, and then from the gear pump oil outlet into the center valve block 2 oil channel a, the faster the motor 1 speed, the gear pump 3 pump oil volume is larger, the oil into the oil channel a after the one-way valve 7, the one-way valve 7 is to ensure that the oil can only from oil channel a to oil channel b, not the reverse b to a. Because the electric proportional valve 9 at this time from the complete loss of power valve stage, the oil cannot enter the oil channel c, only through the oil port P to the AGV lifting cylinder for oil supply, so the oil cylinder at this time the performance of the lifting state, the greater the rotation angle of the resolver knob, the faster the motor 1 speed, the faster the lifting speed of the oil cylinder. When the AGV carrier load is too large, the oil pressure in the oil channel a will be too high, when the pressure exceeds the set value of the overflow valve 6, the unloading port of the overflow valve 6 opens, and the hydraulic system pressure begins to drop, the flow generated by unloading returns to the tank from the overflow port T1 on the center valve block 3.

[0048] As Figure 3 shown: when the AGV begins to execute the unloading action, the motor 1 loses power and does not act, the proportional amplification type electromagnetic coil 8 is powered on, and the electric proportional valve 9 is opened. Because the gravity generated by the fork and the load pushes the oil cylinder piston downward, the oil returns to the center valve block 2 through the oil pipe. Because of the one-way action of the one-way valve 7, the oil cannot return from the oil channel b to the oil channel a, but can only enter the oil channel c through the electric proportional valve 9, and then return to the tank through the T2 return port on the center valve block 2. The greater the rotation angle of the resolver knob, the greater the power supply of the electromagnetic valve coil, the stronger the magnetic effect of the current, the greater the valve opening area of the proportional valve, and the greater the flow of the oil. At this time, the faster the descending speed of the oil cylinder.

[0049] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A proportional lift power unit dedicated to an AGV, characterized by, Including integrated direct current brushless motor (1), center valve block (2), gear pump (3), overflow valve (6), check valve (7), proportional amplification type electromagnetic coil (8) and electric proportional valve (9); The integrated direct current brushless motor (1) is composed of end cover controller and permanent magnet brushless motor, the end cover controller is built-in inverter module, for the direct current of vehicle-mounted battery is converted into alternating current to drive permanent magnet brushless motor, and the rotating speed of permanent magnet brushless motor is controlled by the frequency of end cover controller input alternating current;The gear pump (3) and integrated direct current brushless motor (1) are fixed on the center valve block (2);The overflow valve (6), check valve (7) and electric proportional valve (9) are integrated in the center valve block (2), the overflow valve (6) is used to release pressure when the oil pressure in the center valve block (2) exceeds the preset value, the check valve (7) only allows oil to flow from the gear pump (3) side to the cylinder side;The electric proportional valve (9) and proportional amplification type electromagnetic coil (8) are integrally arranged, the proportional amplification type electromagnetic coil (8) can receive the displacement sensor signal and output different current, control the opening degree of electric proportional valve (9) spool.

2. The proportional lift power unit dedicated for AGV according to claim 1, characterized in that, The integrated direct current brushless motor (1) is provided with a first displacement sensor, the first displacement sensor is installed on the AGV whole vehicle control panel, for adjusting the frequency of end cover controller output alternating current, and then controlling the rotating speed of permanent magnet brushless motor.

3. The proportional lift power unit dedicated for AGV according to claim 1, characterized in that, The electric proportional valve (9) is provided with a second displacement sensor, the second displacement sensor is installed on the AGV whole vehicle control panel, for adjusting the output current of proportional amplification type electromagnetic coil (8), and then controlling the displacement of electric proportional valve (9) spool.

4. The proportional lift power unit dedicated for AGV according to claim 1, characterized in that, The center valve block (2) is provided with P port, T1 port and T2 port;The P port is used for connecting the oil cylinder inlet, for oil output when lifting;The T1 port is used for connecting the oil tank, for oil backflow when the overflow valve (6) releases pressure;The T2 port is used for connecting the oil tank, for oil backflow when descending.

5. The AGV-dedicated proportional lifting power unit according to claim 1, characterized by, The rear end cover of the gear pump (3) is provided with an oil inlet, and the front end cover is provided with an oil outlet, and the oil is pumped into the center valve block (2) from the oil inlet of the rear end cover and the oil outlet of the front end cover.

6. The proportional lift power unit dedicated for AGV according to claim 1, characterized in that, The spool of the electric proportional valve (9) is completely closed in the lifting state, and the opening degree is adjusted according to the current size of proportional amplification type electromagnetic coil (8) in the descending state.

7. The AGV-dedicated proportional lift power unit according to claim 1, characterized by, The gear pump (3) adopts external engagement helical tooth design, and is drivingly connected with the integrated direct current brushless motor (1) through the shaft coupling (4).

8. The proportional lift power unit dedicated for AGV according to claim 1, characterized in that, The overflow valve (6) and electric proportional valve (9) are respectively provided with first screw (5) and second screw (10).

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