A hydraulic control system and method for a lifting hydraulic cylinder of a stepping mechanism

Abstract

The present invention relates to the technical field of metallurgical and forging equipment, and particularly relates to a hydraulic control system and method for a lifting hydraulic cylinder of a walking mechanism. The hydraulic control system for the lifting hydraulic cylinder of the walking mechanism of the present invention includes: an accumulator group, a volume speed control pump group unit, a valve control unit, a directional valve unit, a back pressure oil supplementing unit, and a hydraulic oil tank; one oil port of the volume speed control pump group unit is connected to the accumulator group, and the other oil port of the volume speed control pump group unit is connected to the rodless cavity of the lifting hydraulic cylinder through the valve control unit. The valve control unit can control the opening and closing of the oil circuit between the volume speed control pump group unit and the rodless cavity of the lifting hydraulic cylinder; the oil inlet of the directional valve unit is connected to the accumulator group, the oil outlet of the directional valve unit is connected to the rod chamber of the lifting hydraulic cylinder, and the oil return port of the directional valve unit is connected to the back pressure oil supplementing unit. It can utilize the gravitational potential energy of the object lifted by the lifting hydraulic cylinder, improve the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder, and reduce energy and energy waste.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy and forging equipment, and particularly relates to a hydraulic control system and method for a lifting hydraulic cylinder of a walking mechanism. Background Art

[0002] Walking mechanisms are widely present in mechanical devices such as walking beam reheating furnaces, walking beam cooling beds, and walking beam conveyor chains. They are a kind of continuous motion mechanism that moves materials forward step by step through actions such as rising, advancing, descending, and retreating of the mechanism.

[0003] Walking beam reheating furnaces are widely used in the manufacture of major complete sets of equipment such as metallurgy and mining machinery, especially for pre-forging heating of some advanced steel material forgings or pre-rolling heating of hot-rolled parts. The walking mechanism of a walking beam reheating furnace is generally driven and controlled by multiple hydraulic cylinders, which are mainly used to step-lift and transport heavy objects such as billets to meet the process control requirements of the walking beam reheating furnace. It includes lifting hydraulic cylinders and translation hydraulic cylinders of the furnace bottom machinery, etc.

[0004] The lifting hydraulic cylinder of the furnace bottom machinery is used to drive the reciprocating up and down movement of the furnace bottom machinery step by step. Its movement process is as follows: ① Extend to lift the furnace bottom machinery to receive the steel workpiece; ② Continue to extend to lift the furnace bottom machinery to receive the steel workpiece; ③ Retract while bearing the furnace bottom machinery and the steel workpiece; ④ After unloading the steel workpiece, support the furnace bottom machinery to continue to retract and reset. As a typical lifting hydraulic cylinder of a walking mechanism, it needs to repeatedly lift and lower weights of dozens of tons or even thousands of tons. The object being lifted has a large amount of gravitational potential energy available during the descent. However, the control of the existing lifting hydraulic cylinders of the furnace bottom machinery is based on the control principle of valve-controlled throttle adjustment, resulting in relatively large throttling losses. In addition, when some energy-saving technologies use accumulators for energy recovery, they all adopt single-chamber control technologies and do not consider problems such as oil replenishment in the rod chamber, resulting in problems such as too large accumulator volume, increased costs, and increased failure rates. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention proposes a hydraulic control system and method for a lifting hydraulic cylinder of a walking mechanism, which can utilize the gravitational potential energy of the object lifted by the lifting hydraulic cylinder, improve the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder, and reduce energy and energy waste.

[0006] To achieve the above object, the hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism of the present invention is used to drive the lifting hydraulic cylinder, and it includes: an accumulator group, a volume speed control pump group unit, a valve control unit, a reversing valve unit, a back pressure oil replenishing unit and a hydraulic oil tank; the hydraulic oil tank is used to supply hydraulic oil to the accumulator group and the back pressure oil replenishing unit; one oil port of the volume speed control pump group unit is connected to the accumulator group, and the other oil port of the volume speed control pump group unit is connected to the rodless cavity of the lifting hydraulic cylinder through the valve control unit, and the valve control unit can control the opening and closing of the oil circuit between the volume speed control pump group unit and the rodless cavity of the lifting hydraulic cylinder; the oil inlet of the reversing valve unit is connected to the accumulator group, the oil outlet of the reversing valve unit is connected to the rod chamber of the lifting hydraulic cylinder, and the oil return port of the reversing valve unit is connected to the back pressure oil replenishing unit.

[0007] In one embodiment, the reversing valve unit includes a reversing valve and two groups of one-way valves; the oil inlet of the reversing valve is connected to the accumulator group, the oil outlet A of the reversing valve is connected to the rod chamber of the lifting hydraulic cylinder, and the oil return port of the reversing valve is connected to the back pressure oil replenishing unit; one of the one-way valves connects the oil outlet A to the oil inlet of the reversing valve, so that hydraulic oil can flow unidirectionally from the oil outlet A to the accumulator group; the other one-way valve connects the oil outlet A to the oil return port of the reversing valve, so that hydraulic oil can flow unidirectionally from the back pressure oil replenishing unit to the oil outlet A.

[0008] In one embodiment, the volume speed control pump group unit includes a motor and a hydraulic pump, which are used for pump control debugging of the lifting hydraulic cylinder. The valve control unit includes a hydraulic valve, and the hydraulic valve is connected in one-to-one correspondence with the hydraulic pump. One oil port of the hydraulic pump is connected to the accumulator group, and the other oil port of the hydraulic pump is connected to the hydraulic valve and is connected to the rodless cavity of the lifting hydraulic cylinder through the hydraulic valve.

[0009] In one embodiment, the number of the hydraulic pumps is multiple, the motor drives each hydraulic pump simultaneously, and each hydraulic pump is commonly connected to the rodless cavity of the lifting hydraulic cylinder through the corresponding hydraulic valve.

[0010] In one embodiment, the hydraulic valve is a cartridge type hydraulic lock.

[0011] In one embodiment, the cartridge type hydraulic lock includes a cartridge valve, a shuttle valve and a direction control valve. The two main oil ports of the cartridge valve are respectively connected to the hydraulic pump and the rodless cavity of the lifting hydraulic cylinder. The two inlets of the shuttle valve are respectively connected to the two main oil ports of the cartridge valve. The common oil outlet of the shuttle valve is connected to the oil inlet of the direction control valve, and one oil outlet of the direction control valve is connected to the control port of the cartridge valve.

[0012] In one embodiment, an overflow valve is further provided on the connecting oil path between the hydraulic pump and the hydraulic valve, and the overflow valve is connected to the hydraulic pump and the hydraulic oil tank.

[0013] In one embodiment, a supplementary oil path is provided on the connecting oil path between the hydraulic pump and the hydraulic valve. The supplementary oil path is connected to the oil pipe between the hydraulic pump and the hydraulic valve and the accumulator group. A pressure reducing valve and a one-way supplementary oil valve are provided on the supplementary oil path, so that the hydraulic oil in the accumulator group can be sucked into the hydraulic pump after being decompressed by the pressure reducing valve.

[0014] According to the hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism in any of the above embodiments, the present invention also provides a hydraulic control method for the lifting hydraulic cylinder of the stepping mechanism. The hydraulic control method of the lifting hydraulic cylinder of the stepping mechanism of the present invention includes the following steps:

[0015] S1: In the stage where the lifting hydraulic cylinder rises against the self-weight of the stepping mechanism, control the variable displacement pump unit to make the hydraulic oil flow into the rodless cavity of the lifting hydraulic cylinder, and control the reversing valve unit to connect the rod cavity of the lifting hydraulic cylinder with the accumulator group, and the hydraulic oil in the rod cavity flows back to the accumulator group;

[0016] S2: After the lifting hydraulic cylinder continues to rise and bears an external load, control the reversing valve unit to connect the rod cavity of the lifting hydraulic cylinder with the back-pressure supplementary oil unit, and the hydraulic oil in the rod cavity flows to the back-pressure supplementary oil unit; after the lifting hydraulic cylinder rises in place, use the valve control unit to disconnect the variable displacement pump unit and the rodless cavity of the lifting hydraulic cylinder;

[0017] S3: In the stage where the lifting hydraulic cylinder descends while bearing an external load, use the valve control unit to reconnect the variable displacement pump unit and the rodless cavity of the lifting hydraulic cylinder, control the variable displacement pump unit to change the flow direction of the hydraulic oil, and the lifting hydraulic cylinder shrinks under the action of the gravity of the load, and the hydraulic oil in the rodless cavity is sent back to the accumulator group; the back-pressure supplementary oil unit supplements hydraulic oil to the rod cavity;

[0018] S4: After the external load is unloaded, control the reversing valve unit to connect the rod cavity of the lifting hydraulic cylinder with the accumulator group, the pressure in the rod cavity increases, and under the action of the self-weight of the stepping mechanism, the hydraulic oil in the rodless cavity flows into the accumulator group through the variable displacement pump unit, so that the lifting hydraulic cylinder continues to shrink and descend to reset.

[0019] The hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism in the above embodiments has at least the following advantages:

[0020] (1) When the lifting hydraulic cylinder jacks up the stepping mechanism to bear the external load, the reversing valve unit can connect the rod chamber of the lifting hydraulic cylinder with the accumulator group. The variable displacement pump unit pressurizes the rodless chamber to drive the lifting hydraulic cylinder to extend. Only the relevant gravity and motion resistance of the stepping mechanism need to be overcome, and the energy of the accumulator group remains unchanged. When the stepping mechanism rises after bearing the external load, the reversing valve unit can connect the rod chamber of the lifting hydraulic cylinder with the backpressure oil replenishing unit. The pressure in the rod chamber decreases, and the variable displacement pump unit and the accumulator group cooperate to drive the lifting hydraulic cylinder to extend together. When the stepping mechanism bears the external load and descends, the variable displacement pump unit changes the flow direction of the hydraulic oil. The lifting hydraulic cylinder contracts and descends under the action of the self-weight of the stepping mechanism and the external load gravity, and the backpressure oil replenishing unit replenishes hydraulic oil to the rod chamber. After the external load is unloaded, the reversing valve unit can connect the rod chamber of the lifting hydraulic cylinder with the accumulator group. The internal pressure in the rod chamber increases, and under the combined action of the self-weight of the stepping mechanism, the lifting hydraulic cylinder continues to contract and descend. The gravitational potential energy of the object lifted by the lifting hydraulic cylinder is utilized, the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder is improved, and energy and power waste are reduced.

[0021] (2) A check valve is arranged between the oil outlet A of the reversing valve, the rod chamber and the backpressure oil replenishing unit. When the reversing valve is in a transient closed state during the commutation process, the hydraulic oil can flow into the rod chamber or replenish oil through the check valve, reducing the impact of the commutation process on the internal pressure of the lifting hydraulic cylinder and avoiding unstable telescopic speed.

[0022] (3) The variable displacement pump unit can take into account the synchronous control requirements of multiple hydraulic cylinders, reduce the use of control valves, and simplify the control structure. The motor drives each hydraulic pump simultaneously, which is convenient for controlling the working conditions of each hydraulic pump at the same time and simplifies the control structure of the hydraulic pump.

[0023] (4) The cartridge-type hydraulic lock uses cartridge valves, shuttle valves and directional control valves to lock the driving oil of the lifting hydraulic cylinder when the lifting hydraulic cylinder extends or retracts, simplifying the control oil circuit. The relief valve controls the pressure of the control oil of the variable displacement pump unit for the lifting hydraulic cylinder to avoid unstable telescopic speed. The oil replenishing circuit passes through a pressure reducing valve and a check valve for oil replenishment, so that the connection oil port between the hydraulic pump and the rod chamber always maintains an oil replenishing pressure, and the hydraulic pump does not suck air.

[0024] In the hydraulic control method of the stepping mechanism lifting hydraulic cylinder in the above embodiments, the variable displacement pump unit controls the hydraulic oil in the rodless chamber of the lifting hydraulic cylinder, and the reversing valve unit controls the hydraulic oil in the rod chamber of the lifting hydraulic cylinder. Cooperating with the accumulator group, the gravitational potential energy of the object lifted by the lifting hydraulic cylinder is utilized, the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder is improved, and energy and power waste are reduced. [[ID=!3]] Description of the Drawings

[0025] To more clearly illustrate the specific embodiments of the present invention, the following will briefly introduce the drawings required for the specific embodiments. In all the drawings, the components or parts are not necessarily drawn to actual scale.

[0026] Figure 1 It is a schematic diagram of the hydraulic control system for the lifting hydraulic cylinder of the stepping mechanism provided by an embodiment of the present invention;

[0027] Reference numerals:

[0028] 1 - Lifting hydraulic cylinder, 2 - Accumulator group, 3 - Backpressure oil replenishing unit, 4 - Hydraulic oil tank, 5 - Variable displacement speed control pump unit, 51 - Motor, 52 - Hydraulic pump, 6 - Valve control unit, 61 - Hydraulic valve, 611 - Cartridge valve, 612 - Shuttle valve, 613 - Direction control valve, 62 - Relief valve, 63 - Oil replenishing circuit, 631 - Pressure reducing valve, 632 - Oil replenishing check valve, 7 - Directional valve unit, 71 - Directional valve, 711 - Outlet port A, 72 - Check valve. Specific embodiments

[0029] The following will describe in detail the embodiments of the technical solution of the present invention with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, so they are only examples and cannot be used to limit the protection scope of the present invention. It should be noted that unless otherwise specified, the technical terms or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art to which the present invention belongs.

[0030] In the description of this application, it should be understood that the meaning of "a plurality of" is more than two, unless otherwise clearly and specifically defined. Unless otherwise clearly specified and limited, the terms "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Please refer to Figure 1 , the hydraulic control system for the lifting hydraulic cylinder of the stepping mechanism in one embodiment includes an accumulator group 2, a variable displacement speed control pump unit 5, a valve control unit 6, a directional valve unit 7, a backpressure oil replenishing unit 3 and a hydraulic oil tank 4, which is used to drive the lifting hydraulic cylinder 1 and can utilize the gravitational potential energy of the object lifted by the lifting hydraulic cylinder 1, improve the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder, and reduce energy and energy waste.

[0032] Specifically, the hydraulic oil tank 4 is used to supply hydraulic oil to the accumulator group 2 and the backpressure oil replenishment unit 3. The hydraulic oil tank 4 can be a common hydraulic oil tank. The hydraulic oil tank 4 is simplifiedly represented by a T-tube in the attached drawings. The accumulator group 2 is composed of multiple accumulators connected in parallel. The accumulator group 2 is simplifiedly represented by a P-tube in the attached drawings. The hydraulic oil tank 4 can supply oil to the accumulator group 2 and replenish hydraulic oil through methods such as an oil replenishment pump. The specific method can refer to the prior art. The backpressure oil replenishment unit 3 can be cooling circulating oil with backpressure, which can be achieved by connecting the hydraulic oil tank 4 through a hydraulic oil circulating cooling device of the prior art. The backpressure oil replenishment unit 3 is simplifiedly represented by an M-tube in the attached drawings. It can be understood that, as an oil replenishment device, the oil replenishment pressure of the backpressure oil replenishment unit 3 is less than the working pressure of the accumulator.

[0033] One oil port of the volume speed control pump group unit 5 is connected to the accumulator group 2, and the other oil port of the volume speed control pump group unit 5 is connected to the rodless cavity of the lifting hydraulic cylinder 1 through the valve control unit 6. The valve control unit 6 can control the opening and closing of the oil circuit between the volume speed control pump group unit 5 and the rodless cavity of the lifting hydraulic cylinder 1. The oil inlet of the reversing valve unit 7 is connected to the accumulator group 2, the oil outlet of the reversing valve unit 7 is connected to the rod chamber of the lifting hydraulic cylinder 1, and the oil return port of the reversing valve unit 7 is connected to the backpressure oil replenishment unit 3. Specifically, the volume speed control pump group unit 5 includes a motor 51 and a hydraulic pump 52. It is used to perform pump control debugging on the lifting hydraulic cylinder 1. The valve control unit 6 includes a hydraulic valve 61, and the hydraulic valve 61 is correspondingly connected and arranged with the hydraulic pump 52. One oil port of the hydraulic pump 52 is connected to the accumulator group 2, the other oil port of the hydraulic pump 52 is connected to the hydraulic valve 61, and is connected to the rodless cavity of the lifting hydraulic cylinder 1 through the hydraulic valve 61. Please refer to Figure 1, the oil port A of the hydraulic pump 52 is connected to the hydraulic valve 61, and the oil port B of the hydraulic pump 52 is used to connect to the accumulator group 2 (the connection management diagram is not shown). The volumetric speed-regulating pump group unit 5 controls the flow and pressure of the hydraulic oil by the speed of the motor 51 and the displacement of the hydraulic pump 52; and controls the flow direction of the hydraulic oil by the steering of the motor 51 or the displacement reversal of the hydraulic pump 52. When the lifting hydraulic cylinder 1 lifts the stepping mechanism to bear the external load, the reversing valve unit 7 can make the rod chamber of the lifting hydraulic cylinder 1 connected with the accumulator group 2, and the volumetric speed-regulating pump group unit 5 pressurizes the rodless chamber to drive the lifting hydraulic cylinder 1 to extend. The volumetric speed-regulating pump group unit 5 only needs to overcome the relevant gravity and motion resistance of the stepping mechanism. The amount of hydraulic oil in the accumulator group 2 theoretically remains unchanged, and the stored energy remains unchanged. When the stepping mechanism ascends after receiving an external load, the reversing valve unit 7 connects the rod chamber of the lift hydraulic cylinder 1 with the backpressure oil replenishment unit 3, reducing the pressure in the rod chamber. The volumetric speed-regulating pump unit 5 and the accumulator unit 2 cooperate to extend the lift hydraulic cylinder 1. When the stepping mechanism descends under the external load, the volumetric speed-regulating pump unit 5 changes the direction of the hydraulic oil flow. The lift hydraulic cylinder 1 contracts and descends under the weight of the stepping mechanism and the external load, reducing the pressure in the rod chamber and allowing the backpressure oil replenishment unit 3 to replenish the rod chamber with hydraulic oil. After the external load is unloaded, the reversing valve unit 7 connects the rod chamber of the lift hydraulic cylinder 1 with the accumulator unit 2, increasing the pressure in the rod chamber. Under the combined effect of the weight of the stepping mechanism, the lift hydraulic cylinder 1 continues to contract and descend. This utilizes the gravitational potential energy of the object lifted by the lift hydraulic cylinder 1 and replenishes the control oil circuit with this gravitational potential energy, improving the energy efficiency of the hydraulic control system of the lift hydraulic cylinder 1 and reducing energy consumption and energy waste. When the lifting hydraulic cylinder 1 needs to slow down during the material receiving process, the speed of the motor 51 can be reduced or the displacement of the hydraulic pump 52 can be reduced to achieve speed control, so that the entire stepping mechanism can achieve the desired lifting position and speed control.

[0034] In one embodiment, a relief valve 62 is provided on the oil circuit connecting the hydraulic pump 52 and the hydraulic valve 61. The relief valve 62 connects the hydraulic pump 52 and the hydraulic oil tank 4. The relief valve 62 controls the pressure of the control oil supplied by the displacement speed-regulating pump unit 5 to the lifting cylinder 1, preventing unstable telescopic speed. In one embodiment, a replenishing oil circuit 63 is provided on the oil circuit connecting the hydraulic pump 52 and the hydraulic valve 61. The replenishing oil circuit 63 connects the oil pipe between the hydraulic pump 52 and the hydraulic valve 61 and the accumulator group 2. A pressure reducing valve 631 and a replenishing oil check valve 632 are provided on the replenishing oil circuit 63, allowing the hydraulic oil in the accumulator group 2 to be reduced in pressure by the pressure reducing valve 631 and then drawn into the hydraulic pump 52. The replenishing oil circuit 63, through the pressure reducing valve 631 and the replenishing oil check valve 632, maintains a constant replenishing oil pressure at the oil port connecting the hydraulic pump 52 to the rod chamber, preventing the hydraulic pump 52 from sucking air out of the system.

[0035] In one embodiment, the reversing valve unit 7 includes a reversing valve 71 and two groups of check valves 72. The oil inlet of the reversing valve 71 is connected to the accumulator group 2, the oil outlet A711 of the reversing valve 71 is connected to the rod chamber of the lifting hydraulic cylinder 1, and the oil return port of the reversing valve 71 is connected to the back pressure oil replenishing unit 3. One check valve 72 connects the oil outlet A711 to the oil inlet of the reversing valve 71, enabling the hydraulic oil to flow unidirectionally from the oil outlet A711 to the accumulator group 2. The other check valve 72 connects the oil outlet A711 to the oil return port of the reversing valve 71, enabling the hydraulic oil to flow unidirectionally from the back pressure oil replenishing unit 3 to the oil outlet A711. The reversing valve 71 can be a two-position three-way reversing valve or a two-position four-way reversing valve, etc., which can selectively connect the rod chamber of the lifting hydraulic cylinder 1 to the accumulator group 2 or the back pressure oil replenishing unit 3. A check valve 72 is provided between the oil outlet A711 of the reversing valve 71 and the rod chamber and the back pressure oil replenishing unit 3, which can enable the hydraulic oil to flow into the rod chamber or replenish oil through the check valve 72 when the reversing valve 71 is in a transient closed state during the reversing process, reducing the impact of the reversing process on the pressure inside the lifting hydraulic cylinder 1 and avoiding unstable telescopic speed. In one embodiment, the number of hydraulic pumps 52 is multiple, the motor 51 drives each hydraulic pump 52 simultaneously, and each hydraulic pump 52 is jointly connected to the rodless chamber of the lifting hydraulic cylinder 1 through the corresponding hydraulic valve 61. The variable displacement pump unit 5 can take into account the synchronous control requirements of multiple hydraulic cylinders, reduce the use of control valves, and simplify the control structure. The motor 51 drives each hydraulic pump 52 simultaneously, facilitating the simultaneous control of the working conditions of each hydraulic pump 52 and simplifying the control structure of the hydraulic pump 52.

[0036] In one embodiment, the hydraulic valve 61 is a cartridge-type hydraulic lock. After the lifting hydraulic cylinder 1 is lifted in place, the cartridge-type hydraulic lock cuts off the hydraulic circuit and locks the lifting hydraulic cylinder 1 in the high position for waiting. Specifically, the cartridge-type hydraulic lock includes a cartridge valve 611, a shuttle valve 612, and a direction control valve 613. The two main oil ports of the cartridge valve 611 are respectively connected to the hydraulic pump 52 and the rodless chamber of the lifting hydraulic cylinder 1. The two inlets of the shuttle valve 612 are respectively connected to the two main oil ports of the cartridge valve 611, and the common oil outlet of the shuttle valve 612 is connected to the oil inlet of the direction control valve 613. One oil outlet of the direction control valve 613 is connected to the control port of the cartridge valve 611. The cartridge-type hydraulic lock can use the driving oil of the lifting hydraulic cylinder 1 to lock during the extension or retraction of the lifting hydraulic cylinder 1 through the cartridge valve 611, the shuttle valve 612, and the direction control valve 613, simplifying the control oil circuit. It can be understood that the hydraulic valve 61 can also be a switching valve, a plate-type hydraulically controlled one-way valve, or other hydraulic valves or electrically controlled valves that can control the opening and closing of the oil circuit.

[0037] According to the hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism in the above embodiments, when the lifting hydraulic cylinder 1 jacks up the stepping mechanism to bear the external load, the reversing valve unit 7 can connect the rod chamber of the lifting hydraulic cylinder 1 with the accumulator group 2, and the variable displacement pump unit 5 pressurizes the rodless chamber to drive the lifting hydraulic cylinder 1 to extend. The variable displacement pump unit 5 only needs to overcome the relevant gravity and movement resistance of the stepping mechanism, and the hydraulic oil volume of the accumulator group 2 remains unchanged theoretically, and the stored energy remains unchanged. When the stepping mechanism rises after bearing the external load, the reversing valve unit 7 can connect the rod chamber of the lifting hydraulic cylinder 1 with the back pressure oil filling unit 3, the pressure in the rod chamber decreases, and the variable displacement pump unit 5 and the accumulator group 2 cooperate to drive the lifting hydraulic cylinder 1 to extend together. When the stepping mechanism bears the external load and descends, the variable displacement pump unit 5 changes the flow direction of the hydraulic oil, and the lifting hydraulic cylinder 1 contracts and descends under the action of the self-weight of the stepping mechanism and the gravity of the external load, the pressure in the rod chamber decreases, and the back pressure oil filling unit 3 fills the rod chamber with hydraulic oil. After the external load is unloaded, the reversing valve unit 7 can connect the rod chamber of the lifting hydraulic cylinder 1 with the accumulator group 2, the pressure in the rod chamber increases, and under the combined action of the self-weight of the stepping mechanism, the lifting hydraulic cylinder 1 continues to contract and descend. The gravitational potential energy of the object lifted by the lifting hydraulic cylinder 1 is utilized, and the corresponding gravitational potential energy is used to fill the control oil circuit, improving the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder 1 and reducing energy and energy waste.

[0038] According to the hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism in the above embodiments, the present invention also provides a hydraulic control method for the lifting hydraulic cylinder of the stepping mechanism. The hydraulic control method for the lifting hydraulic cylinder 1 of the stepping mechanism in one embodiment includes the following steps:

[0039] S1. In the stage when the lifting hydraulic cylinder 1 rises against the self-weight of the stepping mechanism. Control the variable displacement pump unit 5 to make the hydraulic oil flow into the rodless chamber of the lifting hydraulic cylinder 1, and control the reversing valve unit 7 to connect the rod chamber of the lifting hydraulic cylinder 1 with the accumulator group 2, and the hydraulic oil in the rod chamber flows back to the accumulator group 2. Specifically, the variable displacement pump unit 5 controls the flow rate and pressure of the hydraulic oil by the rotation speed of the motor 51 and the displacement of the hydraulic pump 52; controls the flow direction of the hydraulic oil by the rotation direction of the motor 51 or the displacement reversing of the hydraulic pump 52. The variable displacement pump unit 5 only needs to do work to overcome the relevant gravity and movement resistance of the stepping mechanism, and the hydraulic oil volume of the accumulator group 2 remains unchanged theoretically, and the stored energy remains unchanged.

[0040] S2. After the lifting hydraulic cylinder 1 continues to rise and bears the external load, the control valve unit 7 is controlled to connect the rod chamber of the lifting hydraulic cylinder 1 with the backpressure oil replenishing unit 3, and the backpressure in the rod chamber is reduced. The volume speed regulating pump unit 5 and the accumulator group 2 cooperate to jointly drive the lifting hydraulic cylinder 1 to extend, and the hydraulic oil in the rod chamber flows to the backpressure oil replenishing unit 3. After the lifting hydraulic cylinder 1 rises in place, the valve control unit 6 is used to disconnect the volume speed regulating pump unit 5 and the rodless chamber of the lifting hydraulic cylinder 1. The reduction of the backpressure in the rod chamber reduces the work demand on the volume speed regulating pump unit 5 and reduces the energy consumption of the system.

[0041] S3. During the stage when the lifting hydraulic cylinder 1 descends while bearing the external load, the valve control unit 6 is used to reconnect the volume speed regulating pump unit 5 and the rodless chamber of the lifting hydraulic cylinder 1. The volume speed regulating pump unit 5 is controlled to change the flow direction of the hydraulic oil. Under the action of the gravity of the load, the lifting hydraulic cylinder 1 contracts, and the hydraulic oil in the rodless chamber is sent back to the accumulator group 2. The backpressure oil replenishing unit 3 replenishes hydraulic oil to the rod chamber.

[0042] S4. After the external load is unloaded, the control valve unit 7 is controlled to connect the rod chamber of the lifting hydraulic cylinder 1 with the accumulator group 2, and the pressure in the rod chamber increases. Under the action of the self-weight of the stepping mechanism, the hydraulic oil in the rodless chamber flows into the accumulator group 2 through the volume speed regulating pump unit 5, so that the lifting hydraulic cylinder 1 continues to contract and descend to reset. Specifically, it also includes controlling the rotation speed and direction of the motor 51 of the volume speed regulating pump unit 5 and the displacement of the hydraulic pump 52 to control the contraction speed.

[0043] The hydraulic control method of the stepping mechanism lifting hydraulic cylinder in the above embodiments controls the hydraulic oil in the rodless chamber of the lifting hydraulic cylinder 1 through the volume speed regulating pump unit 5, and controls the hydraulic oil in the rod chamber of the lifting hydraulic cylinder 1 through the valve control unit 7. Cooperating with the accumulator group 2, it realizes the utilization of the gravitational potential energy of the object lifted by the lifting hydraulic cylinder 1, improves the energy utilization efficiency of the hydraulic control system of the lifting hydraulic cylinder 1, and reduces energy and energy waste.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

Claims

1. A hydraulic control system for a lifting hydraulic cylinder of a stepping mechanism, which is used to drive the lifting hydraulic cylinder, and is characterized in that, Comprising: An accumulator bank, a volume speed control pump unit, a valve control unit, a reversing valve unit, a backpressure oil replenishing unit and a hydraulic oil tank; the hydraulic oil tank is used to supply hydraulic oil to the accumulator bank and the backpressure oil replenishing unit; one oil port of the volume speed control pump unit is connected to the accumulator bank, and the other oil port of the volume speed control pump unit is connected to the rodless cavity of the lifting hydraulic cylinder through the valve control unit, and the valve control unit can control the opening and closing of the oil circuit between the volume speed control pump unit and the rodless cavity of the lifting hydraulic cylinder; the oil inlet of the reversing valve unit is connected to the accumulator bank, the oil outlet of the reversing valve unit is connected to the rod cavity of the lifting hydraulic cylinder, and the oil return port of the reversing valve unit is connected to the backpressure oil replenishing unit; The reversing valve unit includes a reversing valve and two groups of check valves; the oil inlet of the reversing valve is connected to the accumulator bank, the oil outlet A of the reversing valve is connected to the rod cavity of the lifting hydraulic cylinder, and the oil return port of the reversing valve is connected to the backpressure oil replenishing unit; one check valve connects the oil outlet A to the oil inlet of the reversing valve, so that hydraulic oil can flow unidirectionally from the oil outlet A to the accumulator bank; the other check valve connects the oil outlet A to the oil return port of the reversing valve, so that hydraulic oil can flow unidirectionally from the backpressure oil replenishing unit to the oil outlet A; The volume speed control pump unit includes a motor and a hydraulic pump, and is used for pump control debugging of the lifting hydraulic cylinder. The valve control unit includes a hydraulic valve, and the hydraulic valve is arranged in one-to-one communication with the hydraulic pump. One oil port of the hydraulic pump is connected to the accumulator bank, and the other oil port of the hydraulic pump is connected to the hydraulic valve and is connected to the rodless cavity of the lifting hydraulic cylinder through the hydraulic valve.

2. The hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism according to claim 1, characterized in that, The number of the hydraulic pumps is multiple, the motor drives each hydraulic pump simultaneously, and each hydraulic pump is commonly connected to the rodless cavity of the lifting hydraulic cylinder through the corresponding hydraulic valve.

3. The hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism according to claim 1, characterized in that: The hydraulic valve is a cartridge type hydraulic lock.

4. The hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism according to claim 3, characterized in that: The cartridge type hydraulic lock includes a cartridge valve, a shuttle valve and a direction control valve. The two main oil ports of the cartridge valve are respectively connected to the hydraulic pump and the rodless cavity of the lifting hydraulic cylinder. The two inlets of the shuttle valve are respectively connected to the two main oil ports of the cartridge valve. The common oil outlet of the shuttle valve is connected to the oil inlet of the direction control valve. One oil outlet of the direction control valve is connected to the control port of the cartridge valve.

5. The hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism according to claim 1, characterized in that, An overflow valve is further arranged on the connecting oil path between the hydraulic pump and the hydraulic valve, and the overflow valve is connected to the hydraulic pump and the hydraulic oil tank.

6. The hydraulic control system of the lifting hydraulic cylinder of the stepping mechanism according to claim 1, characterized in that, A supplementary oil path is arranged on the connecting oil path between the hydraulic pump and the hydraulic valve. The supplementary oil path connects the oil pipe between the hydraulic pump and the hydraulic valve and the accumulator bank. A pressure reducing valve and a supplementary oil check valve are arranged on the supplementary oil path, so that the hydraulic oil in the accumulator bank can be sucked into the hydraulic pump after being decompressed by the pressure reducing valve.

7. A hydraulic control method for a lifting hydraulic cylinder of a stepping mechanism, which uses the hydraulic control system for the lifting hydraulic cylinder of the stepping mechanism described in any one of claims 1 to 6 to control the lifting hydraulic cylinder, characterized in that Including the following steps: S1: During the stage when the lifting hydraulic cylinder overcomes the self-weight of the stepping mechanism and rises, control the volume speed-regulating pump unit to make the hydraulic oil flow into the rodless cavity of the lifting hydraulic cylinder, and control the reversing valve unit to connect the rod cavity of the lifting hydraulic cylinder with the accumulator group, and the hydraulic oil in the rod cavity flows back to the accumulator group; S2: After the lifting hydraulic cylinder continues to rise and bears an external load, control the reversing valve unit to connect the rod cavity of the lifting hydraulic cylinder with the back-pressure oil supplement unit, and the hydraulic oil in the rod cavity flows to the back-pressure oil supplement unit; after the lifting hydraulic cylinder rises in place, use the valve control unit to disconnect the volume speed-regulating pump unit and the rodless cavity of the lifting hydraulic cylinder; S3: During the stage when the lifting hydraulic cylinder descends while bearing an external load, use the valve control unit to reconnect the volume speed-regulating pump unit and the rodless cavity of the lifting hydraulic cylinder, control the volume speed-regulating pump unit to change the flow direction of the hydraulic oil, and the lifting hydraulic cylinder contracts under the action of the gravity of the load, and the hydraulic oil in the rodless cavity is sent back to the accumulator group; the back-pressure oil supplement unit supplements hydraulic oil to the rod cavity; S4: After the external load is unloaded, control the reversing valve unit to connect the rod cavity of the lifting hydraulic cylinder with the accumulator group, the pressure in the rod cavity increases, and under the action of the self-weight of the stepping mechanism, the hydraulic oil in the rodless cavity flows into the accumulator group through the volume speed-regulating pump unit, so that the lifting hydraulic cylinder continues to contract and descend to reset.

Images