Belt conveyor with energy recovery function and operation control method thereof

Abstract

The present invention discloses a belt conveyor with energy recovery function and its operation control method, which adopts a motor, a motor and an accumulator as the driving system, the roller is connected to the frequency conversion motor through a gear mechanism, and the roller is connected to the hydraulic motor through a gear mechanism and a clutch; the clutch contactor is used to control the clutch to realize the on and off of the motor and the roller; the accumulator is used to release oil pressure and provide energy to drive the hydraulic motor during the startup to normal operation stage, the low speed adjustment to high speed operation stage or the material increase stage; it absorbs oil and stores energy during the high speed adjustment to low speed operation stage, the material reduction stage and the braking stage. The present invention uses the energy of the accumulator to assist the conveyor in full load and heavy load startup, meets the application under extreme working conditions, can effectively reduce the installed power of the main motor, better avoid the motor from working in the low efficiency area for a long time, and improve energy utilization.

Description

Technical Field

[0001] The invention relates to the technical field of belt conveyors, in particular to a belt conveyor with an energy recovery function and an operation control method thereof. Background Art

[0002] Belt conveyors, the primary transport equipment for bulk materials, feature large transport capacity, long-distance haulage, a high degree of automation, and continuous transport. They are widely used in ports, docks, coal mines, metallurgy, and grain production, playing a particularly crucial role in coal mining. With the increasing depth of coal mining and advances in mining technology, the use of high-speed, long-distance, intelligent, and high-capacity belt conveyors has increased, particularly in the form of down-conveying belt conveyors. Down-conveying belt conveyors, which transport materials from high to low levels, have lagged behind in development compared to overhead and horizontal belt conveyors. This is due to their limited application and complex operating conditions. Depending on the load, the drive motor may be in either motoring or generating mode, making braking control more difficult. Improper braking can easily lead to unsafe accidents such as slippage, material spillage, and runaway. However, down-conveying belt conveyors also offer significant advantages. They significantly reduce the workload of roadway mining and significantly reduce infrastructure costs and construction cycles.

[0003] The difficulty in resolving the braking problem for down-belt conveyors lies in the fact that the downward component of the material's gravity, acting as an accelerating force, is in the same direction as the material's motion. When the conveyor meets certain inclination angles and load conditions, the downward component of the material's force becomes greater than the motor's driving force, causing the motor to switch to a dynamic braking state. If the load torque exceeds the maximum braking torque generated by the motor itself, and the conveyor is not equipped with a reliable speed-regulating braking system, the motor will lose control, causing the conveyor to accelerate continuously until it runs out of control. Comprehensive analysis shows that how to handle braking energy is the core issue that needs to be addressed in research on braking systems for down-belt conveyors.

[0004] Currently, most down-feed conveyors achieve braking or speed regulation by converting the kinetic and potential energy of materials during downward transport into heat loss in the braking system. This is also known as energy-dissipative braking. Common methods include the use of external brakes such as hydraulic brakes, mechanical brakes, and external brake resistors. For down-feed belt conveyors with large inclinations and large transport volumes, the braking energy required for energy-dissipative braking is very high, resulting in significant energy losses. This not only places very high demands on the braking system's braking capacity, but also wastes resources and can easily cause significant environmental pollution. Furthermore, due to explosion-proof requirements in mines, energy-dissipative braking also requires ambient temperature limits.

[0005] Compared to energy-consuming braking, there's also the less commonly used variable frequency regenerative braking. This system, based on a frequency converter drive, modulates the electrical energy generated by the motor's generator operation through the converter's regenerative unit and then transmits it to the grid for recycling. However, the regenerative braking system requires a functioning power supply from the electrical system. Sudden power outages completely eliminate its braking capacity, potentially leading to braking accidents. Furthermore, improper regenerative control can impact the grid.

[0006] Based on the above-mentioned deficiencies and defects of the prior art, the present invention proposes a belt conveyor with energy recovery function and its operation control method. The idea is different from the two technical routes of the prior art. The present invention adopts a variable frequency motor, a hydraulic motor and an accumulator as the driving system. The roller is connected to the variable frequency motor through a gear mechanism, and the roller is connected to the hydraulic motor through a gear mechanism and a clutch; the clutch contactor controls the clutch to realize the connection and disconnection of the motor and the roller; the accumulator is used to release oil pressure and provide energy to drive the hydraulic motor in the startup to normal operation stage, the low speed adjustment to high speed operation stage or the material increase stage; it absorbs oil and stores energy in the high speed adjustment to low speed operation stage, the material reduction stage and the braking stage. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a belt conveyor with energy recovery function and its operation control method, which adopts a variable frequency motor, a hydraulic motor and an accumulator as the control mode of the drive system. When the conveyor is adjusted from high speed to low speed, the conveyed material is reduced, braking and other operating stages, the energy released by the conveyor is recovered, and the recovered energy is used from startup to normal operation, from low speed to high speed operation and material increase stage, thereby saving energy consumption.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0009] A belt conveyor with energy recovery function and its operation control method, the belt conveyor uses an electric motor, a motor and an accumulator as the driving system, the roller is connected to the frequency conversion motor through a gear mechanism, and the roller is further connected to the hydraulic motor through a gear mechanism and a clutch; the clutch contactor is used to control the clutch to realize the connection and disconnection of the motor and the roller; the accumulator is used to release oil pressure and provide energy to drive the hydraulic motor during the startup to normal operation stage, the low speed adjustment to high speed operation stage or the material increase stage; it absorbs oil and stores energy during the high speed adjustment to low speed operation stage, the material reduction stage and the braking stage.

[0010] The operation control method specifically includes the following steps:

[0011] Step 1: Start to normal operation stage:

[0012] Step 1-1: Start from full load or heavy load to normal operation:

[0013] Step 1-1-1: Start motors 1 and 2, de-energize the solenoid valves of the variable pumps, and start pumping oil. The current of the electric proportional relief valve II is adjusted to the preset value. The current of the solenoid valves of the variable pumps gradually increases, and the three-position four-way valve and the two-position two-way valve I are energized. The motor brakes are released, and the motors start running.

[0014] Step 1-1-2: The clutch contactor opens, engaging the clutch and the motor. The oil output by the variable displacement pump enters the motor. The power of the motor and the second motor is transmitted to the roller through gear mechanism I and gear mechanism II. Driven by the motor and the second motor, the conveyor belt starts to start at full load.

[0015] Step 1-1-3: After reaching the set speed, the accumulator control valve assembly starts to release oil until the conveyor belt reaches a stable speed, and the full load or heavy load is successfully started;

[0016] Step 1-2: Start from no-load or light-load to normal operation:

[0017] Step 1-2-1: Start the No. 2 motor to drive the drum to run. The variable pump solenoid valve is not energized and the variable pump does not output oil. After the drum speed reaches the set speed, the current of the electric proportional relief valve II is adjusted to the preset value. The three-position four-way valve and the two-position two-way valve I are energized, the motor brake is opened, and the motor starts to run.

[0018] Step 1-2-2: The clutch contactor opens, engaging the clutch and the motor. The oil output from accumulator I enters the motor through the two-way balancing valve. The power of the motor and motor No. 2 is transmitted to the roller through gear mechanism I and gear mechanism II. The conveyor belt starts running under the joint drive of the motor and motor No. 2.

[0019] Step 1-2-3: As the conveyor belt speed increases, the speed at which the accumulator control valve assembly releases oil is adjusted according to the current of the two-position two-way proportional valve until the conveyor belt reaches a stable speed, and the no-load or light-load start is successful;

[0020] Step 2: Adjust from low speed to high speed or increase material:

[0021] Step 2-1: The No. 2 motor is in the running state, the variable pump solenoid valve is not energized, and the electric proportional relief valve II is adjusted to the preset value; the three-position four-way valve and the two-position two-way valve I are energized, the motor brake is opened, and the motor starts to run;

[0022] Step 2-2: The clutch contactor opens to engage the clutch and the motor. The variable displacement pump stops outputting oil. The oil output from accumulator I enters the motor through the two-way balancing valve. The power of the motor and the second motor is transmitted to the drum through gear mechanism I and gear mechanism II.

[0023] Step 2-3: Under the combined action of the motor drive and the second motor, the conveyor belt speed gradually increases. As the speed increases, the rate at which the accumulator control valve assembly releases oil is adjusted according to the current of the two-position two-way proportional valve until the conveyor belt reaches a stable speed or the material weight reaches a stable level.

[0024] Step 3: Adjust from high speed to low speed, or material reduction stage:

[0025] Step 3-1: The No. 2 motor is in the running state, the solenoid valve of the variable pump is de-energized, and the current of the electric proportional relief valve II is adjusted to the preset value; the three-position four-way valve, the two-position two-way valve I, and the variable pump are all de-energized, and the two-position two-way valve III is energized, the motor brake is released, and the motor starts to run;

[0026] Step 3-2: The clutch contactor opens, engaging the clutch and the motor. The variable pump stops outputting oil, and accumulator I of the accumulator control valve assembly receives and stores the high-pressure oil output by the motor. Under the combined action of the motor and motor No. 2, the conveyor belt speed gradually decreases.

[0027] Step 3-3: As the conveyor belt speed changes, the speed at which the accumulator control valve assembly receives oil is adjusted according to the current of the two-position two-way proportional valve until the conveyor belt reaches a stable speed or the speed is reduced to a stable weight of material;

[0028] Step 4, braking phase:

[0029] Step 4-1: Before braking, the No. 2 motor is in the running state, the variable pump is de-energized, and the electric proportional relief valve II is adjusted to the preset value; the 3-position 4-way valve, 2-position 2-way valve I, 2-position 2-way valve II, and variable pump are all de-energized, while the 2-position 2-way valve III is energized, the motor brake is released, and the motor starts to run;

[0030] Step 4-2: The clutch contactor opens to engage the clutch and the motor. The variable pump stops outputting oil, and the accumulator I of the accumulator control valve assembly receives and stores the high-pressure oil output by the motor. Under the combined action of the motor and the second motor, the conveyor belt speed gradually decreases.

[0031] Step 4-3: As the conveyor belt speed changes, the speed at which the accumulator control valve assembly receives oil is adjusted according to the current of the two-position two-way proportional valve until the conveyor belt speed reaches zero, and the conveyor belt braking is completed.

[0032] Further preferably, the motor brake is turned on and off in the following manner:

[0033] The 2-position 2-way valve IV, the 2-position four-way valve II, and the 2-position 2-way valve are switched after being energized. The oil in the variable pump, the accumulator control valve assembly, and the accumulator II passes through the 2-position 2-way valve IV, the pressure reducing valve, and the 2-position four-way valve II and enters the motor brake. The motor brake is opened and the motor can rotate.

[0034] When the two-position four-way valve II loses power, the motor brake is depressurized and closed, and the motor loses power and stops rotating.

[0035] Further preferably, the clutch contactor is controlled to open and close in the following manner:

[0036] The 2-position 2-way valve IV, the 2-position four-way valve I, and the 2-position 2-way valve are switched after being energized. The oil in the variable pump, the accumulator control valve assembly, and the accumulator II passes through the 2-position 2-way valve IV, the pressure reducing valve, and the 2-position four-way valve I and enters the clutch contactor, allowing the motor to provide power to the drum.

[0037] After the two-position four-way valve I loses power, the clutch contactor releases pressure and the drum is disconnected from the motor power.

[0038] Further preferably, the control method of filling and releasing the oil of the accumulator control valve assembly is:

[0039] The variable pump charges the accumulator: the current of the variable pump, 2-position 2-way proportional valve, and electric proportional relief valve I increases, the 3-position 4-way valve, 2-position 2-way valve II, and 2-position 3-way valve are energized and reversed, and accumulator I is charged. According to the detection of pressure sensor I, pressure sensor II, and pressure sensor III, the charging is completed when the set pressure value is reached.

[0040] The accumulator releases oil: the 2-position 2-way valve II and the 2-position 3-way valve are energized and reversed, the 2-position 2-way proportional valve is energized, and the accumulator I releases oil.

[0041] Further preferably, when adjusting from high speed to low speed operation or in the material reduction stage or braking stage, the two-position two-way valve III is energized, and when the accumulator I absorbs and releases oil, the opening of the two-position two-way proportional valve is proportionally controlled according to the detection of pressure sensor I, pressure sensor II and pressure sensor III to control the speed at which the accumulator I absorbs and releases oil.

[0042] Further preferably, pressure sensor II and pressure sensor III are symmetrically distributed at the oil inlet and outlet of the motor. After detecting the pressure, the pressure difference between the two ends of the motor is calculated, thereby calculating the torque of the hydraulic oil acting on the motor.

[0043] Further preferably, during the process of starting or stopping the motor, if the motor has air absorption phenomenon, oil is replenished through the one-way valve; if the pressure exceeds the set value during the operation of the motor, overflow is performed through the one-way valve and the electric proportional relief valve II; if a pressure shock occurs, the oil flows back to the oil tank through the two-position two-way valve I, the throttle valve, and the three-position four-way valve.

[0044] Further preferably, the set speed in step 1-1-3 is 2%-5% of the maximum speed of the belt conveyor, and the stable speed is the maximum speed; the set speed in step 1-2-1 is 2%-5% of the maximum speed of the roller.

[0045] The present invention has the following beneficial effects:

[0046] (1) The conveying system control method provided by the present invention recovers the energy released by the conveyor when the conveyor is adjusted from high speed to low speed, when the conveyed material is reduced, when braking, etc.; and uses the recovered energy in the stages from startup to normal operation, from low speed to high speed operation, and when the conveyed material is increased, thereby saving energy consumption.

[0047] (2) The present invention utilizes the energy of the accumulator to assist the conveyor in starting up at full load or heavy load, meeting the application under extreme working conditions. It can effectively reduce the installed power of the main motor, better avoid the motor from working in the low-efficiency area for a long time, and improve energy utilization.

[0048] (3) The system of the present invention has strong expandability. The accumulator control valve assembly and the motor can be expanded according to the power requirements and operating conditions of the conveyor (such as upward type, downward type, sudden change in material weight, etc.).

[0049] (4) The present invention can reduce the impact by coordinating the throttle valve and the electric proportional relief valve according to the working conditions, thereby ensuring smooth starting and stopping of the motor.

[0050] (5) When the accumulator of the present invention absorbs and releases oil, the opening of the valve is proportionally controlled according to the detection of the pressure sensor, and the speed of the accumulator absorbing and releasing oil is well controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the operating principle of the prior art.

[0052] Figure 2 This is a diagram showing the relationship between power and time when the conveyor starts at full load.

[0053] Figure 3 It is a principle diagram of the belt conveyor operation control method with energy recovery function of the present invention.

[0054] The components are: 1. Check valve; 2a. Electric proportional relief valve I; 2b. Electric proportional relief valve II; 3. Two-position three-way valve; 4. Shuttle valve; 5. Two-position two-way proportional valve; 6a. Accumulator I; 6b. Accumulator II; 7. Accumulator control valve assembly; 8a. Pressure sensor I; 8b. Pressure sensor II; 8c. Pressure sensor III; 9a. Motor No. 1; 9b. Motor No. 2; 10. Variable pump; 11. Three-position four-way valve; 12. Throttle valve; 13a. Two-position two-way valve I; 13b. Two-position two-way valve II; 13c. Two-position two-way valve III; 13d. Two-position two-way valve IV; 14. Two-way balancing valve; 15. Motor brake; 16. Motor; 17. Clutch; 18. Clutch contactor; 19a. Gear mechanism I; 19b. Gear mechanism II; 20. Roller; 21a. Two-position four-way valve I; 21b. Two-position four-way valve II; 22. Two-position two-way valve; 23. Overflow valve; 24. Pressure reducing valve. DETAILED DESCRIPTION

[0055] In the description of the present invention, it should be understood that the terms "left side," "right side," "upper," "lower," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Terms such as "first" and "second" do not indicate the importance of components and therefore should not be construed as limitations on the present invention. The specific dimensions used in this embodiment are intended only to illustrate the technical solution and do not limit the scope of protection of the present invention.

[0056] The present invention will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0057] The existing conveyor belt drive mode is usually one, two or more variable frequency motors drive a roller, and the roller drives the conveyor belt. Taking the two-motor drive mode as an example, its power transmission is as follows: Figure 1 After the two variable frequency motors are connected through a gear mechanism and a reducer, the two power sources jointly drive the conveyor rollers, thereby driving the conveyor belt.

[0058] Variable frequency motors can meet user requirements for motor speed in down-feed conveyors, enabling controlled starting and stopping, and implementing controllable speed regulation. Variable frequency speed regulation technology generally utilizes vector control, offering significant advantages in both motor speed regulation characteristics and load capacity. It offers a wide range of settings for acceleration times during startup and deceleration times during stopping, effectively controlling the soft start and stop of flexible conveyor loads and achieving power matching between drive units.

[0059] When designing the installed power of the belt conveyor drive device, the existing technology generally selects it according to the full-load working condition. However, in order to meet the power requirements under the extreme working condition of full-load starting, the installed power of the selected motor is much larger. Taking the full-load starting of a small-sized conveyor as an example, Figure 2 As shown in the figure, the power required before approaching constant speed operation is high, but after reaching the constant speed stage, the power required drops significantly, and the motor often operates in the low-efficiency zone. To meet the power requirements of the extreme operating condition of full-load startup, the motor power is far greater than the power required for stable operation, causing the motor to operate in the low-efficiency zone for a long time, resulting in energy waste. At the same time, when the conveyor adjusts from high speed to low speed, reduces the amount of material being transported, or brakes, the conveyor will release a lot of energy, which is wasted.

[0060] Therefore, the present invention proposes a belt conveyor with energy recovery function and its operation control method, which adopts a motor, a motor and an accumulator as the driving system, and the roller is connected to the variable frequency motor through a gear mechanism, and the roller is connected to the hydraulic motor through a gear mechanism and a clutch; the clutch contactor is used to control the clutch to realize the on and off of the motor and the roller. The present invention recovers the energy released by the conveyor when the conveyor is adjusted from high speed to low speed operation, the conveyed material is reduced, braking and other operating stages; and uses the recovered energy from startup to normal operation, from low speed to high speed operation and material increase stage, thereby saving energy consumption. At the same time, the energy of the accumulator is used to assist the conveyor in full load and heavy load startup to meet the application under extreme working conditions, which can effectively reduce the installed power of the main motor, better avoid the motor from working in the low efficiency area for a long time, and improve energy utilization.

[0061] The main power devices of the belt conveyor of the present invention are an electric motor and a motor. The motor provides oil through a variable pump and an accumulator to transmit power, thereby driving the roller and driving the belt to run or stop.

[0062] The motor brake 15 is used to control the rotation and stop of the motor 16. The opening and closing control mode of the motor brake 15 is as follows:

[0063] After the two-position two-way valve IV 13d, the two-position four-way valve II 21b, and the two-position two-way valve 22 are energized, the oil in the variable pump 10, the accumulator control valve assembly 7, and the accumulator II 6b passes through the two-position two-way valve IV 13d, the pressure reducing valve 24, and the two-position four-way valve II 21b and enters the motor brake 15. The motor brake 15 opens, and the motor 16 can rotate. After the two-position four-way valve II 21b loses power, the motor brake 15 is depressurized and closed, and the motor 16 loses power and stops rotating.

[0064] The clutch contactor 18 is used to control the clutch 17 to realize the on / off of the motor 16 and the drum 20. The opening and closing control mode of the clutch contactor 18 is as follows:

[0065] When energized, the 2-position 2-way valve IV 13d, the 2-position 4-way valve I 21a, and the 2-position 2-way valve 22 reverse direction. The oil in the variable pump 10, the accumulator control valve assembly 7, and the accumulator II 6b flows through the 2-position 2-way valve IV 13d, the pressure reducing valve 24, and the 2-position 4-way valve I 21a and enters the clutch contactor 18, allowing the motor 16 to provide power to the drum 20. When the 2-position 4-way valve I 21a loses power, the clutch contactor 18 releases pressure, and the drum 20 is disconnected from the motor 16.

[0066] The difference between the two-position two-way valve 22 here and the two-position two-way valves I-IV that appear later is that the two-position two-way valve 22 is a normally open type, while the two-position two-way valves I-IV are a normally closed type.

[0067] The accumulator control valve assembly 7 is used to control the accumulator I6a, filling and releasing the oil in the accumulator I6a. The control method is as follows:

[0068] The variable pump charges the accumulator: the current in the variable pump 10, the 2 / 2-way proportional valve 5, and the electric proportional relief valve I 2a increases, the 3 / 4-way valve 11, the 2 / 2-way valve II 13b, and the 2 / 3-way valve 3 are energized and switched, and the accumulator I 6a is charged. According to the detection of pressure sensor I 8a, pressure sensor II 8b, and pressure sensor III 8c, the charging is completed when the set pressure value is reached; the accumulator releases the oil: the 2 / 2-way valve II 13b and the 2 / 3-way valve 3 are energized and switched, the 2 / 2-way proportional valve 5 is energized, and the accumulator I 6a releases the oil.

[0069] The opening pressure of the electric proportional relief valve Ⅰ2a and the electric proportional relief valve Ⅱ2b here can be changed by the control program, which is different from the relief valve 23. The relief valve 23 is a fixed-value relief valve, and its valve is set in advance, and the opening pressure cannot be changed by the control program.

[0070] The shuttle valve is used for pressure selection. The pressure of the accumulator I6a and the two-position two-way proportional valve 5, whichever has a greater pressure, is selected for pressure release or pressure maintenance of the stored energy.

[0071] like Figure 3 As shown, a belt conveyor operation control method with energy recovery function specifically includes the following steps:

[0072] Step 1: Start to normal operation stage:

[0073] Step 1-1: Full load or heavy load start-up to normal operation: In this stage, both motors run simultaneously, and the variable pump and accumulator supply oil together to drive the motors to rotate;

[0074] Step 1-1-1, start motor No. 1 9a and motor No. 2 9b, the solenoid valve of the variable pump 10 is not energized, the pump's swing angle is very small, and its displacement is basically 0; the current of the electric proportional relief valve II2b is adjusted to a preset value, which is determined in combination with the load and is usually slightly larger than the working current.

[0075] It should be noted that the electric proportional relief valve Ⅱ2b in steps 1-1-1, 1-2-1, 2-1, 3-1 and 4-1 are all adjusted to the preset value. Due to different working conditions, the value that needs to be adjusted is also different, depending on the working conditions, especially full load or near full load, light load, it is necessary to adjust the current to a certain value after calculation according to the program, and this value is usually slightly larger than the working current.

[0076] The solenoid valve current of the variable pump 10 gradually increases, the three-position four-way valve 11 and the two-position two-way valve I 13a are energized, the motor brake 15 is opened, and the motor 16 starts to run.

[0077] Step 1-1-2, the clutch contactor 18 is opened to combine the clutch 17 with the motor 16; the oil output by the variable pump 10 enters the motor 16; the power of the motor 16 and the second motor 9b is transmitted to the roller 20 through the gear mechanism I 19a, the gear mechanism II 19b and the reducer. Under the joint drive of the motor 16 and the second motor 9b, the conveyor belt starts to start at full load.

[0078] Step 1-1-3: After reaching a certain speed, the accumulator control valve assembly 7 starts to release oil until the conveyor belt reaches a stable speed and the full load or heavy load is successfully started.

[0079] According to the technical parameter requirements, the motor, accumulator I6a and accumulator control valve assembly 7 can be increased, with no limit on the number, and there is no limit on the connection method between the motor and the drum, such as coupling drive, belt drive or any other form.

[0080] Step 1-2: No-load or light-load start-up to normal operation: In this stage, the accumulator releases oil to drive the motor;

[0081] Step 1-2-1, the second motor 9b starts, driving the roller 20 to run, the solenoid valve of the variable pump 10 is not energized, and the variable pump 10 does not output oil; after the speed of the roller 20 reaches a certain value, the current of the electric proportional relief valve II2b is adjusted to the preset value, the three-position four-way valve 11 and the two-position two-way valve I13a are energized, the motor brake 15 is opened, and the motor 16 starts to run.

[0082] Step 1-2-2, the clutch contactor 18 is opened to combine the clutch 17 with the motor 16, and the oil output by the accumulator I6a enters the motor 16 through the two-way balancing valve 14; at this time, the two-position two-way valve II13b is opened, and the two-position three-way valve 3 is energized, and the flow is adjusted by the accumulator I6a. At the same time, the electric proportional relief valve I2a is also energized to adjust the relief pressure; the power of the motor 16 and the second motor 9b is transmitted to the roller 20 through the gear mechanism I19a and the gear mechanism II19b, and the conveyor belt starts to run under the joint drive of the motor 16 and the second motor 9b.

[0083] Step 1-2-3: As the conveyor belt speed increases, the speed at which the accumulator control valve assembly 7 releases the oil is adjusted according to the current of the two-position two-way proportional valve 5 until the conveyor belt reaches a stable speed, and the no-load or light-load start is successful.

[0084] Step 2: Adjust from low speed to high speed operation or material adding stage: In this stage, the accumulator releases oil to drive the motor;

[0085] Step 2-1: Motor No. 2 9b is in running state, the solenoid valve of the variable pump 10 is not energized, and the electric proportional relief valve II2b is adjusted to the preset value; the three-position four-way valve 11 and the two-position two-way valve I 13a are energized, the motor brake 15 is opened, and the motor 16 starts to run.

[0086] Step 2-2: The clutch contactor 18 is opened to engage the clutch 17 with the motor 16. The variable pump 10 does not output oil. The oil output by the accumulator I6a enters the motor 16 through the two-way balancing valve 14. The power of the motor 16 and the second motor 9b is transmitted to the drum 20 through the gear mechanism I 19a and the gear mechanism II 19b.

[0087] Step 2-3: Under the joint action of motor 16 and No. 2 motor 9b, the conveyor belt speed gradually increases. As the speed increases, the speed at which the accumulator control valve assembly 7 releases oil is adjusted according to the current of the two-position two-way proportional valve 5 until the conveyor belt reaches a stable speed or the material is added to a stable weight.

[0088] Step 3: Adjust from high speed to low speed operation, or material reduction stage: In this stage, the accumulator absorbs oil and stores kinetic energy.

[0089] Step 3-1, the second motor 9b is in the running state, the solenoid valve of the variable pump 10 is not energized, and the current of the electric proportional relief valve II2b is adjusted to the preset value; the three-position four-way valve 11, the two-position two-way valve I13a, and the variable pump 10 are all not energized, the two-position two-way valve III13c is energized, the motor brake 15 is opened, and the motor 16 starts to run.

[0090] Step 3-2: The clutch contactor 18 is opened to engage the clutch 17 with the motor 16. The variable pump 10 does not output oil. The accumulator Ⅰ6a of the accumulator control valve assembly 7 receives and stores the high-pressure oil output by the motor 16. The motor works in the pump state and is driven by the roller to pump oil to the accumulator. At this time, the motor acts as a brake.

[0091] Step 3-3: Under the joint action of motor 16 and motor No. 2 9b, the speed of the conveyor belt gradually decreases; as the speed of the conveyor belt changes, the speed at which the accumulator control valve assembly 7 receives oil is adjusted according to the current of the two-position two-way proportional valve 5 until the conveyor belt reaches a stable speed or is reduced to a stable weight of material.

[0092] Step 4, braking phase:

[0093] Step 4-1. Before braking, motor No. 2 9b is in operation, variable displacement pump 10 is de-energized, and electric proportional relief valve II 2b is adjusted to a preset value. Three-position four-way valve 11, two-position two-way valve I 13a, two-position two-way valve II 13b, and variable displacement pump 10 are all de-energized, while two-position two-way valve III 13c is energized. Motor brake 15 is released, and motor 16 begins to operate.

[0094] Step 4-2: The clutch contactor 18 is opened to engage the clutch 17 with the motor 16. The variable pump 10 does not output oil. The accumulator I6a of the accumulator control valve assembly 7 receives and stores the high-pressure oil output by the motor 16. Under the joint action of the motor 16 and the second motor 9b, the conveyor belt speed gradually decreases.

[0095] Step 4-3: As the conveyor belt speed changes, the speed at which the accumulator control valve assembly 7 receives oil is adjusted according to the current of the two-position two-way proportional valve 5 until the conveyor belt speed reaches zero, and the conveyor belt braking is completed.

[0096] The valve mechanisms of the present invention are all equipped with electromagnetic valves, and the power on and off of the electromagnetic valves are controlled by a controller.

[0097] When adjusting from high speed to low speed operation or in the material reduction stage or braking stage, the two-position two-way valve III13c is energized, and when the accumulator I6a absorbs and releases oil, the opening of the two-position two-way proportional valve 5 is proportionally controlled according to the detection of pressure sensor I8a, pressure sensor II8b and pressure sensor III8c to control the speed of oil absorption and release by the accumulator I6a.

[0098] During the process of starting or stopping the motor, if the motor 16 has cavitation, oil is replenished through the one-way valve; if the pressure exceeds the set value during the operation of the motor 16, overflow is caused by the one-way valve and the electric proportional relief valve II 2b; if a pressure shock occurs, the oil flows back to the oil tank through the two-position two-way valve I 13a, the throttle valve 12, and the three-position four-way valve 11.

[0099] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A belt conveyor operation control method with energy recovery function, characterized in that: The roller (20) is connected to the second motor (9b) through the gear mechanism II (19b), and the roller (20) is connected to the motor (16) through the gear mechanism I (19a) and the clutch (17); the clutch contactor (18) is used to control the clutch (17) to realize the connection and disconnection of the motor (16) and the roller (20); The accumulator control valve assembly (7) is connected to the variable pump (10) and the No. 1 motor (9a). The accumulator control valve assembly (7) is used to release oil pressure and provide energy to drive the hydraulic motor during the start-up to normal operation stage, the low speed adjustment to high speed operation stage, or the material increase stage; and absorb oil and store energy during the high speed adjustment to low speed operation stage, the material reduction stage, or the braking stage. The accumulator control valve assembly (7) includes a one-way valve (1), an electric proportional relief valve I (2a), a two-position three-way valve (3), a two-position two-way proportional valve (5), and an accumulator I (6a) connected in sequence; the accumulator I (6a) is connected to the motor (16) via a two-position two-way valve III (13c); One outlet of the No. 1 motor (9a) is connected to the clutch contactor (18) through a two-position two-way valve IV (13d), a pressure reducing valve (24), a relief valve (23), a two-position two-way valve (22), a two-position four-way valve I (21a); ​​the other outlet of the No. 1 motor (9a) is connected to the motor brake through a two-position two-way valve IV (13d), a pressure reducing valve (24), a two-position four-way valve II (21b); The control method includes the following steps: Step 1: Start to normal operation stage: Step 1-1: Start from full load or heavy load to normal operation: Step 1-1-1, the No. 1 motor (9a) and the No. 2 motor (9b) are started, the solenoid valve of the variable pump (10) is not energized, the variable pump (10) does not output oil, and the current of the electric proportional relief valve II (2b) is adjusted to a preset value; the current of the solenoid valve of the variable pump (10) gradually increases, the three-position four-way valve (11) and the two-position two-way valve I (13a) are energized, the motor brake (15) is opened, and the motor (16) starts to operate; Step 1-1-2: The clutch contactor (18) is opened to connect the clutch (17) with the motor (16); the oil output by the variable pump (10) enters the motor (16); the power of the motor (16) and the second motor (9b) is transmitted to the roller (20) through the gear mechanism I (19a) and the gear mechanism II (19b). Under the joint drive of the motor (16) and the second motor (9b), the conveyor belt starts to start with full load; Step 1-1-3: After reaching the set speed, the accumulator control valve assembly (7) starts to release oil until the conveyor belt reaches a stable speed and the full load or heavy load is successfully started; Step 1-2: Start from no-load or light-load to normal operation: Step 1-2-1, the second motor (9b) starts, driving the roller (20) to run, the solenoid valve of the variable pump (10) is not energized, and the variable pump (10) does not output oil; after the speed of the roller (20) reaches the set speed, the current of the electric proportional relief valve II (2b) is adjusted to the preset value, the three-position four-way valve (11) and the two-position two-way valve I (13a) are energized, the motor brake (15) is opened, and the motor (16) starts to run; Step 1-2-2: The clutch contactor (18) is opened to connect the clutch (17) with the motor (16), and the oil output from the accumulator I (6a) enters the motor (16) through the two-way balance valve (14); the power of the motor (16) and the second motor (9b) is transmitted to the roller (20) through the gear mechanism I (19a) and the gear mechanism II (19b), and the conveyor belt starts to run under the joint drive of the motor (16) and the second motor (9b); Step 1-2-3: As the conveyor belt speed increases, the speed at which the accumulator control valve assembly (7) releases the oil is adjusted according to the current of the two-position two-way proportional valve (5) until the conveyor belt reaches a stable speed, and the no-load or light-load start is successful; Step 2: Adjust from low speed to high speed or increase material: Step 2-1: The second motor (9b) is in the running state, the solenoid valve of the variable pump (10) is not energized, and the electric proportional relief valve II (2b) is adjusted to the preset value; the three-position four-way valve (11) and the two-position two-way valve I (13a) are energized, the motor brake (15) is opened, and the motor (16) starts to run; Step 2-2: The clutch contactor (18) is opened to engage the clutch (17) with the motor (16). The variable displacement pump (10) does not output oil. The oil output from the accumulator I (6a) enters the motor (16) through the two-way balancing valve (14). The power of the motor (16) and the second motor (9b) is transmitted to the roller (20) through the gear mechanism I (19a) and the gear mechanism II (19b). Step 2-3: Under the combined action of the motor (16) and the second motor (9b), the conveyor belt speed gradually increases. As the speed increases, the speed at which the accumulator control valve assembly (7) releases the oil is adjusted according to the current of the two-position two-way proportional valve (5) until the conveyor belt reaches a stable speed or the material weight reaches a stable level. Step 3: Adjust from high speed to low speed, or material reduction stage: Step 3-1: The second motor (9b) is in the running state, the solenoid valve of the variable pump (10) is not energized, and the current of the electric proportional relief valve II (2b) is adjusted to the preset value; the three-position four-way valve (11), the two-position two-way valve I (13a), and the variable pump (10) are all not energized, the two-position two-way valve III (13c) is energized, the motor brake (15) is opened, and the motor (16) starts to run; Step 3-2: The clutch contactor (18) is opened to connect the clutch (17) and the motor (16). The variable pump (10) does not output oil, and the accumulator I (6a) of the accumulator control valve assembly (7) receives and stores the high-pressure oil output by the motor (16). Under the combined action of the motor (16) and the second motor (9b), the conveyor belt speed gradually decreases. Step 3-3: As the conveyor belt speed changes, the speed at which the accumulator control valve assembly (7) receives the oil is adjusted according to the current of the two-position two-way proportional valve (5) until the conveyor belt reaches a stable speed or decreases to a stable weight of material; Step 4, braking phase: Step 4-1: Before braking, the No. 2 motor (9b) is in the running state, the variable pump (10) is de-energized, and the electric proportional relief valve II (2b) is adjusted to the preset value; the three-position four-way valve (11), the two-position two-way valve I (13a), the two-position two-way valve II (13b), and the variable pump (10) are all de-energized, the two-position two-way valve III (13c) is energized, the motor brake (15) is opened, and the motor (16) starts to operate; Step 4-2: The clutch contactor (18) is opened to connect the clutch (17) and the motor (16). The variable pump (10) does not output oil. The accumulator I (6a) of the accumulator control valve assembly (7) receives and stores the high-pressure oil output by the motor (16). Under the combined action of the motor (16) and the second motor (9b), the conveyor belt speed gradually decreases. Step 4-3: As the conveyor belt speed changes, the speed at which the accumulator control valve assembly (7) receives the oil is adjusted according to the current of the two-position two-way proportional valve (5) until the conveyor belt speed reaches zero, and the conveyor belt braking is completed.

2. The belt conveyor operation control method with energy recovery function according to claim 1, characterized in that: The opening and closing control of the motor brake (15) is as follows: After the two-position two-way valve IV (13d), the two-position four-way valve II (21b), and the two-position two-way valve (22) are energized, the oil from the variable pump (10), the accumulator control valve assembly (7), and the accumulator II (6b) enters the motor brake (15) through the two-position two-way valve IV (13d), the pressure reducing valve (24), and the two-position four-way valve II (21b). The motor brake (15) opens, and the motor (16) can rotate. After the two-position four-way valve II (21b) loses power, the motor brake (15) is depressurized and closed, and the motor (16) loses power and stops rotating.

3. The belt conveyor operation control method with energy recovery function according to claim 1, characterized in that: The opening and closing control mode of the clutch contactor (18) is: After the two-position two-way valve IV (13d), the two-position four-way valve I (21a), and the two-position two-way valve (22) are energized, the oil from the variable pump (10), the accumulator control valve assembly (7), and the accumulator II (6b) enters the clutch contactor (18) through the two-position two-way valve IV (13d), the pressure reducing valve (24), and the two-position four-way valve I (21a), so that the motor (16) provides power to the roller (20); After the two-position four-way valve I (21a) loses power, the clutch contactor (18) releases pressure and the drum (20) is disconnected from the motor (16).

4. The belt conveyor operation control method with energy recovery function according to claim 1, characterized in that: The control method for filling and releasing the oil of the accumulator control valve assembly (7) is as follows: The variable pump charges the accumulator: the current of the variable pump (10), the two-position two-way proportional valve (5), and the electric proportional relief valve I (2a) increases, the three-position four-way valve (11), the two-position two-way valve II (13b), and the two-position three-way valve (3) are energized and reversed, and the accumulator I (6a) is charged. According to the detection of the pressure sensor I (8a), the pressure sensor II (8b), and the pressure sensor III (8c), the charging is completed when the set pressure value is reached; The accumulator releases oil: the 2 / 2-way valve II (13b) and the 2 / 3-way valve (3) are energized and switched, the 2 / 2-way proportional valve (5) is energized, and the accumulator I (6a) releases oil.

5. The belt conveyor operation control method with energy recovery function according to claim 1, characterized in that: When the speed is adjusted from high to low or during the material reduction or braking phase, the two-position two-way valve III (13c) is energized and the accumulator I (6a) absorbs and releases the oil. The opening of the two-position two-way proportional valve (5) is proportionally controlled based on the detection of the pressure sensor I (8a), the pressure sensor II (8b) and the pressure sensor III (8c), thereby controlling the speed at which the accumulator I (6a) absorbs and releases the oil.

6. The belt conveyor operation control method with energy recovery function according to claim 5, characterized in that: Pressure sensor II (8b) and pressure sensor III (8c) are symmetrically distributed at the oil inlet and outlet of the motor (16). After detecting the pressure, the pressure difference between the two ends of the motor (16) is calculated, thereby calculating the torque of the hydraulic oil acting on the motor.

7. The belt conveyor operation control method with energy recovery function according to claim 1, characterized in that: During the process of starting or stopping the motor, if the motor (16) experiences cavitation, oil is replenished through the one-way valve; if the pressure exceeds the set value during the operation of the motor (16), overflow is performed through the one-way valve and the electric proportional relief valve II (2b); if a pressure shock occurs, the oil flows back to the oil tank through the two-position two-way valve I (13a), the throttle valve (12), and the three-position four-way valve (11).

8. The belt conveyor operation control method with energy recovery function according to claim 1, characterized in that: The set speed in step 1-1-3 is 2%-5% of the maximum speed of the belt conveyor, and the stable speed is the maximum speed; the set speed in step 1-2-1 is 2%-5% of the maximum speed of the roller.

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