Working machine and hydraulic control system thereof

Abstract

The invention belongs to the technical field of operation machinery and provides operation machinery and a hydraulic control system thereof, the system comprises a plurality of execution units, a power unit and a control unit, and the power unit comprises a first oil pump and a second oil pump which are used for supplying oil to the execution units respectively; the control unit is used for correspondingly switching the oil supply mode of the power unit according to a preset corresponding relation between a preset condition and the oil supply mode of the power unit according to a target action to be executed by the operation machine; wherein the oil supply mode of the power unit comprises common oil supply of the first oil pump and the second oil pump and independent oil supply of one of the first oil pump and the second oil pump. According to the system, different oil supply modes are switched at proper time, and load flow matching can be achieved at low cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of operating machinery, and in particular relates to a hydraulic control system of an operating machinery and the operating machinery. Background Art

[0002] When operating a machine, the load's hydraulic flow requirements vary depending on the operating conditions and actions being performed. For existing machines, the hydraulic system's flow control methods primarily include valve control and pump control.

[0003] Valve control refers to a system that uses an electro-hydraulic proportional valve or servo valve group to control the flow rate from the oil pump to the actuator. This system offers high control accuracy, fast response, and excellent stability. However, to maintain control accuracy, valve control requires the oil pump output flow rate to exceed the flow rate required by the actuator. This results in the pump output power exceeding the power required by the actuator during operation. The excess pump power is wasted by the proportional valve or servo valve group, resulting in high system energy consumption.

[0004] Pump control refers to the use of a variable pump for driving, which matches the pump's output power with the power required by the load by changing the pump's displacement. Although this type of system can achieve lower energy consumption under the same action, the variable pump servo control is complex and the assembly cost is high, so it is difficult to popularize in the mid- and low-end markets. Summary of the Invention

[0005] In view of the above-mentioned defects or shortcomings, the present invention provides a hydraulic control system for an operating machine and an operating machine, aiming to solve the technical problem that the hydraulic control system of the existing aerial working machine is difficult to achieve both low cost and low energy consumption at the same time.

[0006] To achieve the above-mentioned objectives, the present invention provides a hydraulic control system for industrial machinery, which includes a plurality of execution units, a power unit and a control unit, wherein the power unit includes a first oil pump and a second oil pump for supplying oil to the execution units respectively; the control unit is used to switch the oil supply mode of the power unit according to the preset correspondence between "preset conditions-oil supply mode of the power unit" according to the target action to be performed by the working machinery; wherein the oil supply mode of the power unit includes the first oil pump and the second oil pump supplying oil together, and one of the first oil pump and the second oil pump supplying oil alone.

[0007] In an embodiment of the present invention, the first oil pump and the second oil pump can be double pumps and can also be metering pumps respectively. The power unit also includes a driving element for driving the first oil pump and the second oil pump to operate, and the high-efficiency speed range of the driving element overlaps with the high-efficiency speed range of the correspondingly connected first oil pump and / or second oil pump.

[0008] In an embodiment of the present invention, when the first oil pump operates in the overlapping high-efficiency speed range, the flow rate required for operation of at least one of the preselected execution units is within the output flow rate range of the first oil pump; and / or, when the second oil pump operates in the overlapping high-efficiency speed range, the flow rate required for operation of at least one of the preselected execution units is within the output flow rate range of the second oil pump; And / or, when the first oil pump and the second oil pump operate in overlapping high-efficiency speed ranges, the flow rate required for operation of at least one of the preselected execution units is within the range of the sum of the output flow rates of the first oil pump and the second oil pump.

[0009] In an embodiment of the present invention, the overlapping high-efficiency speed range includes a peak-efficiency speed range of the driving element, and when the first oil pump operates in the peak-efficiency speed range, a difference between a flow rate required for operation of at least one of the preselected execution units and an output flow rate of the first oil pump is less than a preset value; and / or, when the second oil pump operates in the peak efficiency speed range, a difference between a flow rate required for operation of at least one preselected execution unit and an output flow rate of the second oil pump is less than a preset value; and / or, when the first oil pump and the second oil pump operate in a peak efficiency speed range, a difference between a flow rate required for operation of at least one preselected execution unit and a sum of output flow rates of the first oil pump and the second oil pump is less than a preset value; The control unit is further configured to control the driving element to operate in a peak efficiency speed range when the pre-selected execution unit is working.

[0010] In an embodiment of the present invention, the pre-selected execution unit is an execution unit whose startup probability is higher than a set threshold value according to the big data analysis.

[0011] In an embodiment of the present invention, the driving element may be a motor.

[0012] In an embodiment of the present invention, a first unloading oil circuit is provided between the pumping port of the first oil pump and the return oil circuit, the system further includes an unloading switching unit, the unloading switching unit includes a first loading valve for controlling the on-off of the first unloading oil circuit, a second unloading oil circuit is provided between the pumping port of the second oil pump and the return oil circuit, the unloading switching unit further includes a second loading valve for controlling the on-off of the second unloading oil circuit; wherein, it is used to switch the on-off of the first loading valve and the second loading valve according to the preset correspondence between "preset conditions-oil supply mode of the power unit" according to the target action to be performed by the operating machinery.

[0013] In an embodiment of the present invention, the displacement of the first oil pump is greater than the displacement of the second oil pump.

[0014] In an embodiment of the present invention, the working machine is an aerial work machine, the plurality of execution units include a lifting cylinder, the target action includes platform lifting, and the control unit is specifically configured as follows: Receive platform lifting instructions; Generate dual pump common oil supply instruction; In response to the dual-pump common oil supply command, the first oil pump and the second oil pump are controlled to jointly supply oil according to the dual-pump common oil supply command.

[0015] In an embodiment of the present invention, the work machine is an aerial work machine, the plurality of execution units include a front steering cylinder, the target action includes front wheel steering, and the control unit is specifically configured as follows: Receive front wheel steering instructions; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump is controlled to unload and the second oil pump is controlled to supply oil according to the small pump independent oil supply instruction.

[0016] In an embodiment of the present invention, the working machine is an aerial work machine, the plurality of execution units further include a rear steering cylinder, the target action includes four-wheel steering, and the control unit is specifically configured as follows: Receive four-wheel steering instructions; Generate a separate oil supply instruction for the large pump; In response to the large pump's separate oil supply instruction, the first oil pump is controlled to supply oil according to the four-wheel steering instruction, and the second oil pump is controlled to unload.

[0017] In an embodiment of the present invention, the working machine is an aerial work machine, the plurality of execution units include outrigger drive cylinders, the target actions include synchronous extension and synchronous retraction of the outriggers, and the control unit is specifically configured as follows: Receive instructions for synchronous extension of outriggers; Generate dual pump common oil supply instruction; In response to a dual-pump common oil supply instruction, controlling the first oil pump and the second oil pump to jointly supply oil according to the dual-pump common oil supply instruction; and / or; receiving a synchronous retraction instruction of the outriggers; Generate a separate oil supply instruction for the large pump; In response to the large pump independent oil supply instruction, the first oil pump is controlled to supply oil according to the large pump independent oil supply instruction, and the second oil pump is controlled to unload.

[0018] In an embodiment of the present invention, the working machine is an aerial work machine, the plurality of execution units include outrigger drive cylinders, the target action includes individual extension and retraction of the outriggers, and the control unit is specifically configured as follows: Receive instructions for extending and retracting the outriggers individually; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump is controlled to unload and the second oil pump is controlled to supply oil according to the small pump independent oil supply instruction.

[0019] In an embodiment of the present invention, the working machine is an aerial work machine, the plurality of execution units include a platform telescopic cylinder, the target action includes platform telescopic movement, and the control unit is specifically configured as follows: Receive platform expansion and contraction instructions; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump is controlled to unload and the second oil pump is controlled to supply oil according to the small pump independent oil supply instruction.

[0020] To achieve the above object, the present invention further provides a working machine, wherein the working machine includes the hydraulic control system described above.

[0021] Through the above technical solution, the hydraulic control system of the working machine provided by the embodiment of the present invention has the following beneficial effects: This system can select the appropriate oil supply method to match the flow rate according to the different actions performed by the execution unit. For example, when the required flow rate of the action being performed is large, the oil supply method of the first oil pump and the second oil pump can be changed, so that the first oil pump and the second oil pump with the larger displacement can supply oil alone, or the first oil pump and the second oil pump can supply oil together, thereby achieving a large flow output of the power unit. When the required flow rate of the action being performed is small, the first oil pump and the second oil pump with the smaller displacement can be controlled to supply oil alone to reduce the flow output of the power unit and avoid wasting excess flow. In this way, the oil supply method of the power unit is switched according to the different actions performed by the working machine, so that the output flow of the system can be as close as possible to the required flow rate of the load, thereby reducing the waste of unnecessary energy in the system to a certain extent and reducing the energy consumption of the system. Moreover, this control method does not require the introduction of a complex feedback mechanism and is very low cost.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide an understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 is a hydraulic principle diagram of a hydraulic control system of a working machine according to an embodiment of the present invention; Figure 2 2 is a control connection diagram of a hydraulic control system according to an embodiment of the present invention.

[0024] Description of Reference Numerals 1. Actuator unit; 11. Lifting cylinder; 12. Front steering cylinder; 13. Rear steering cylinder; 14. Left front outrigger cylinder; 15. Left rear outrigger cylinder; 16. Right front outrigger cylinder; 17. Right rear outrigger cylinder; 18. Platform telescopic cylinder; 2. Power unit; 21. First oil pump; 22. Second oil pump; 23. Driving element; 3. Unloading switching unit; 31. First loading valve; 32. Second loading valve; 41. One-way check valve; 42. Safety valve; 43. Fuel tank. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0026] The hydraulic control system for a working machine according to the present invention will be described below with reference to the accompanying drawings.

[0027] The hydraulic system is the core of the drive control of operating machinery, and its component costs account for the bulk of the overall machine construction cost. Reducing the component cost and energy consumption of the hydraulic system will be of great significance to market development, especially for the mid- and low-end markets. Lower prices and lower energy consumption can make users more favored.

[0028] Taking aerial work machinery as an example, aerial work machinery is a kind of equipment that lifts people or goods to a certain height for work. It is mainly composed of a body, an arm, an operating platform and a hydraulic system.

[0029] Aerial work platforms require varying flow rates at the load end, depending on the operating conditions and actions being performed. To ensure consistent control of system input and required flow rates within limited costs, many existing aerial work platforms incorporate proportional valves or servo valve blocks in their hydraulic systems. To maintain vehicle performance, these aerial work platforms operate with a pump that delivers a constant flow rate. The proportional valve or servo valve block adjusts the flow rate to the load end, achieving high-performance operation of the actuators. This constant flow rate is throttled by the proportional valve or servo valve block, wasting excess energy.

[0030] As energy conservation and environmental protection become increasingly popular, operating machinery is undergoing multiple improvements to reduce the energy consumption of hydraulic systems. Pump control, for example, is a major area of ​​improvement. By using a variable pump with stepless speed regulation as a pump unit, the pump's output flow rate can be consistently matched to the load's required flow rate by adjusting the pump's speed, significantly reducing the system's operating energy consumption.

[0031] However, the price of a variable displacement pump is much higher than that of an ordinary fixed displacement pump, and the system also requires the introduction of a complex load feedback mechanism, making it difficult to popularize in the mid- and low-end markets.

[0032] In view of this, the present invention discloses a hydraulic control system for an operating machine, such as Figure 1 As shown, the hydraulic control system includes several execution units 1, a power unit 2 and a control unit.

[0033] The power unit 2 includes a first oil pump 21 and a second oil pump 22 for supplying oil to the actuator unit 1 respectively. The first oil pump 21 and the second oil pump 22 are metering pumps.

[0034] The control unit is configured to switch the fuel supply mode of the power unit 2 according to the target action to be performed by the work machine and the preset correspondence between "preset conditions and fuel supply mode of the power unit". The fuel supply modes of the power unit 2 include joint fuel supply by the first oil pump 21 and the second oil pump 22, and fuel supply by only one of the first oil pump 21 and the second oil pump 22.

[0035] The preset conditions in "Preset Conditions - Oil Supply Method of Power Unit" may include the action to be performed by the working machine, pressure fluctuations of each execution unit 1, movement speed of each execution unit 1, specific manual operation instructions received by the control unit, etc. For example, the action to be performed is used.

[0036] This system can select an appropriate oil supply method to match the flow rate according to the different actions performed by the execution unit 1. For example, when the required flow rate of the action to be performed is large, the oil supply method of the first oil pump 21 and the second oil pump 22 can be changed, so that the one with the larger displacement of the first oil pump 21 and the second oil pump 22 can supply oil alone, or the first oil pump 21 and the second oil pump 22 can supply oil together, thereby achieving a large flow output of the power unit 2. When the required flow rate of the action to be performed is small, the one with the smaller displacement of the first oil pump 21 and the second oil pump 22 can be controlled to supply oil alone to reduce the flow output of the power unit 2 and avoid wasting excess flow. In this way, the oil supply method of the power unit 2 is switched according to the different actions performed by the working machine, so that the output flow of the system can be as close as possible to the required flow rate of the load, thereby reducing the waste of unnecessary energy of the system to a certain extent and reducing the energy consumption of the system. Moreover, this control method does not require the introduction of a complex feedback mechanism and is very low in cost.

[0037] In this embodiment, the system preferably utilizes a dual-displacement pump in the design of power unit 2. Conventional fixed-displacement pumps are much cheaper than variable-displacement pumps. This system utilizes a dual-displacement pump architecture and selects an appropriate oil supply strategy based on operating conditions. While maintaining low costs, this system addresses, to a certain extent, the technical dilemma of "comparing energy consumption with cost" in flow matching in existing hydraulic control systems for aerial work equipment. Of course, variable-displacement pumps can also achieve similar results, if costs permit.

[0038] like Figure 1As shown, in this embodiment, to further reduce the cost of the power unit 2, the first oil pump 21 and the second oil pump 22 can be a duplex pump and driven by a common drive element 23. For example, the first oil pump 21 can be the front pump of the duplex pump, and the second oil pump 22 can be the rear pump of the duplex pump. Of course, if costs permit, the first oil pump 21 and the second oil pump 22 can also be driven by two independently operated drive elements 23.

[0039] In this embodiment, when selecting the first oil pump 21 and the second oil pump 22, the first oil pump 21 and the second oil pump 22 with a suitable high-efficiency speed range can be selected to match the operating speed of the drive element 23, thereby ensuring the efficient operation of the power unit 2 and achieving the purpose of further reducing the system energy consumption.

[0040] Specifically, taking the first oil pump 21 and the second oil pump 22 as a dual pump and driven by a motor as an example, the high-efficiency speed range of the motor is assumed to be 2500-3500 rpm, and when the first oil pump 21 and the second oil pump 22 are selected, a pump with a high-efficiency speed range of 2400-3000 rpm can be selected. The overlapping high-efficiency speed range of the two is 2500-3000 rpm. When the motor operates in the overlapping high-efficiency speed range of 2500-3000 rpm, the pump also operates efficiently.

[0041] In this embodiment, the overlapping high-efficiency speed range preferably includes the peak high-efficiency speed of the drive element 23 .

[0042] In this embodiment, after selecting the first oil pump 21 and the second oil pump 22 with a suitable high-efficiency speed range, the system energy consumption can be further reduced by selecting the first oil pump 21 and the second oil pump 22 with suitable displacement parameters.

[0043] Specifically, when selecting the displacement, the displacement parameters of the first oil pump 21 and the second oil pump 22 must satisfy at least one of the following conditions.

[0044] Condition 1: When the first oil pump 21 operates in the overlapping high-efficiency speed range, the flow rate required for the operation of at least one pre-selected execution unit 1 is within the output flow rate range of the first oil pump 21; Condition 2: When the second oil pump 22 operates in the overlapping high-efficiency speed range, the flow rate required for the operation of at least one pre-selected execution unit 1 is within the output flow rate range of the second oil pump 22; Condition three: when the first oil pump 21 and the second oil pump 22 operate in overlapping high-efficiency speed ranges, the flow rate required for operation of at least one pre-selected execution unit 1 is within the range of the sum of the output flow rates of the first oil pump 21 and the second oil pump 22 .

[0045] Taking aerial work machinery as an example, the execution unit 1 of the aerial work machinery includes a lifting cylinder 11, a steering cylinder, a leg drive cylinder, a platform telescopic cylinder 18, etc. When the four groups of cylinders are working, it is assumed that the required displacement of each is 135L / min, 30L / min, 75L / min, and 50L / min respectively.

[0046] Assuming the overlapping high-efficiency speed range is 2500-3000 rpm, the displacement of the first oil pump 21 can be selected to be 27 ml / rpm. The corresponding output flow range within the high-efficiency speed range is 27*(2500-3000) / 1000 = 67.5-81 L / min. This range includes the 75 L / min required for the outrigger drive cylinder to operate. When the outrigger drive cylinder is operating, by controlling the first oil pump 21 to supply oil alone, the system can generate a maximum of 6 L / min of flow waste, effectively reducing the system's energy consumption.

[0047] Furthermore, the displacement of the second oil pump 22 can be set to 18 ml / rev, which translates to an output flow rate range of 45-54 L / min, covering the 50 L / min required for operation of the platform telescoping cylinder 18. The maximum combined displacement of the first and second oil pumps 21 and 22 is 81 + 54 = 135 L / min. When the lift cylinder 11 needs to operate, controlling both pumps to supply oil together ensures that the system flow rate precisely matches the load required for the lift.

[0048] It is understandable that the above specific values ​​are only examples. In actual products, the displacement of the first oil pump 21 and the second oil pump 22 can be adaptively changed according to different product models.

[0049] In this embodiment, the preselected execution unit 1 is the execution unit 1 whose startup probability is higher than a set threshold value according to the big data analysis. That is, when selecting the displacement of the first oil pump 21 and the second oil pump 22, the execution unit 1 with higher usage frequency is preferentially matched.

[0050] Continuing with the example of aerial work machinery, according to big data analysis, when users use aerial work machinery, the probability of using the outrigger extension and retraction function is 91%, the probability of using the platform lifting function is 95%, and the probability of using the steering function is 75%. Assuming that the required flow rates of the lifting cylinder 11, steering cylinder, outrigger drive cylinder, and platform extension and retraction cylinder 18 are 110L / min, 40L / min, 70L / min, and 60L / min respectively, and the overlapping high-efficiency speed range is 2500-3000rpm, when selecting the displacement of the first oil pump 21 and the second oil pump 22, a pump with a displacement of 25 ml / rpm (the flow adjustment range in the high-efficiency speed range is 62.5-75L / min) can be selected as the first oil pump 21, and a pump with a displacement of 15 ml / rpm (the flow adjustment range in the high-efficiency speed range is 37.5-45L / min) can be selected as the second oil pump 22.

[0051] When the user needs to lift, the power unit 2 can select the first oil pump 21 and the second oil pump 22 to supply oil together to generate a maximum flow rate of 120L / min to match the flow rate requirement of platform lifting.

[0052] When the user needs to extend or retract the outriggers, the power unit 2 can select the first oil pump 21 to supply oil separately to match the flow requirement of 70L / min when the outriggers are extended or retracted.

[0053] When steering is required, the power unit 2 can select the second oil pump 22 to supply oil separately to match the flow requirement of the steering cylinder of 40L / min.

[0054] By matching the displacement of the first oil pump 21 and the second oil pump 22, the aerial work machinery is in a state of good flow load matching most of the time. Only when the user needs to perform some less common operations will the flow matching and adjustment effect be poor in the overlapping high-efficiency speed range.

[0055] In this embodiment, parameters such as the high-efficiency operating ranges of the oil pump and drive element 23, and the pump displacement, can be further selected so that the overlapping high-efficiency speed ranges include the peak-efficiency speed range of the drive element 23. When the work machine is in a primary operating condition, the control unit can be configured to control the drive element 23 to operate in the peak-efficiency speed range. When the work machine is in other secondary or non-primary operating conditions, the control unit can be configured to control the drive element 23 to operate at an appropriate speed within the high-efficiency speed range.

[0056] It is understood that the classification of primary, secondary, and non-primary operating conditions can be based on the probability of each function being used as determined by big data analysis. By sorting the probability of use from high to low, the primary, secondary, and non-primary operating conditions of the operating machine can be determined. Of course, in some cases, a more granular classification of operating conditions can be employed.

[0057] In this embodiment, the preselected actuators 1 are preferentially selected from those with the highest probability of startup. When selecting the displacement of the first and second oil pumps 21 and 22, priority is given to matching the actuators 1 required for the primary operating condition. If selection remains after this matching, further matching is performed with actuators 1 required for secondary operating conditions. Through this matching selection and control by the control unit, the power unit's drive element 23 operates at peak efficiency under the primary operating condition, while maintaining high efficiency under other operating conditions.

[0058] In this embodiment, the selection and matching principle can be further as follows: when the first oil pump 21 operates in the peak efficiency speed range, the difference between the flow required for the work of at least one pre-selected execution unit 1 and the output flow of the first oil pump 21 is less than a preset value.

[0059] And / or, when the second oil pump 22 operates in the peak efficiency speed range, the difference between the flow rate required for operation of at least one pre-selected execution unit 1 and the output flow rate of the second oil pump 22 is smaller than a preset value.

[0060] And / or, when the first oil pump 21 and the second oil pump 22 operate in the peak efficiency speed range, the difference between the flow required for operation of at least one pre-selected execution unit 1 and the sum of the output flow rates of the first oil pump 21 and the second oil pump 22 is less than a preset value.

[0061] Assuming that the peak high-efficiency operation speed of the motor is 2800 rpm, when the aerial work machinery is working, according to big data analysis, the probability of leg extension and platform lifting being used exceeds 90%, and this probability value is at the forefront. Therefore, the lifting cylinder 11 and the leg drive cylinder can be selected as the pre-selected execution units, and the leg extension and platform lifting can be defined as the main operating conditions of the aerial work machinery.

[0062] The oil pumps are selected to have displacements of 25 ml / rev and 15 ml / rev, respectively, to match the flow rates required by the lift cylinder 11 and the outrigger drive cylinder. When the user needs to extend or extend the outriggers or lift the platform, by controlling the drive element 23 to operate at 2800 rpm (peak efficiency speed range) and controlling the first oil pump to supply oil alone or both pumps to supply oil together, the required flow rates of 70 L / min for outrigger extension and 110 L / min for lift cylinder 11 can be matched, respectively, with a flow margin of less than 2%. When the aerial work machine is performing other actions, by controlling the speed of the drive element 23 within the efficient speed range of 2500-2800 rpm, the system flow rate can be adjusted within a certain range, effectively matching the flow requirements of different actions and ensuring that the power unit 2 is operating efficiently.

[0063] In this embodiment, the driving element 23 may be an engine in addition to being a motor.

[0064] To switch the fuel supply mode of the power unit 2, Figure 1 As shown, in one embodiment of the present invention, a first unloading oil circuit may be provided between the oil delivery port and the oil return circuit of the first oil pump 21, and a second unloading oil circuit may be provided between the oil delivery port and the oil return circuit of the second oil pump 22. A first loading valve 31 for on-off control is provided on the first unloading oil circuit, and a second loading valve 32 for on-off control is provided on the second unloading oil circuit. The unloading oil circuit and the loading valve together constitute the unloading switching unit 3.

[0065] When the first oil pump 21 and the second oil pump 22 are required to supply oil together, the first loading valve 31 and the second loading valve 32 may be switched to a cut-off state.

[0066] When only the first oil pump 21 is needed to supply oil, the first loading valve 31 can be switched to the cut-off state, and the second loading valve 32 can be switched to the on state. At this time, the hydraulic oil output by the second oil pump 22 will flow back to the oil tank 43 through the second unloading oil circuit.

[0067] Likewise, when only the second oil pump 22 is required to supply oil, the second loading valve 32 may be switched to a cut-off state, and the first loading valve 31 may be switched to an on state.

[0068] In this embodiment, the first loading valve 31 and the second loading valve 32 may be reversing valves with an on position and a shutoff position, wherein the shutoff position may be one-way shutoff and reverse conduction.

[0069] like Figure 2 As shown, in this embodiment, the control unit can control the on / off states of the first loading valve 31 and the second loading valve 32 respectively according to different action instructions.

[0070] Continuing with the example of aerial work machinery, Figure 1 As shown, the execution unit 1 of the aerial work machinery may include a lifting cylinder 11. When the aerial work machinery needs to lift the platform, the operator will press the lifting button to generate a platform lifting instruction. After receiving the platform lifting instruction, the control unit will not only control the action of the control valve group of the lifting cylinder 11, but also respond to the platform lifting instruction and control the first oil pump 21 and the second oil pump 22 to supply oil together according to the platform lifting instruction.

[0071] A duplex pump system preferably consists of two pumps, one large and one small. The large pump has a larger displacement than the small pump. The large pump is typically loaded when the system requires a higher flow rate, while the small pump is primarily used for low-flow or auxiliary oil supply. When both the large and small pumps are unloaded, they idle, and the system's energy consumption is limited to that of the large and small pumps idling.

[0072] For example, if the first oil pump 21 is a large pump, when the platform is raised, to ensure sufficient lifting force and speed, the system requires a relatively large flow rate, generally exceeding the rated maximum displacement of the first oil pump 21. Therefore, to ensure that the lift cylinder 11 can successfully complete its operation, the control unit generates a dual-pump joint oil supply command upon receiving the platform raise command. Based on this command, the control unit controls the closing of both the first loading valve 31 and the second loading valve 32, allowing the first and second oil pumps 21, 22 to jointly supply oil to the lift cylinder 11, ensuring the driving force and extension speed of the lift cylinder 11.

[0073] Some aerial work machines may have two working modes: fast lifting and energy-saving lifting. The flow rate required for the lifting cylinder 11 in the two modes is different. In view of this, the present embodiment may also set a proportional valve between the second oil pump 22 and the execution unit 1. When lifting smoothly, by controlling the proportional opening of the proportional valve, the first oil pump 21 is fully supplied with oil and the second oil pump 22 is partially supplied with oil, so as to achieve a smooth and slow lifting of the platform. When the load carried by the platform is large or the lifting speed needs to be accelerated, the first loading valve 31 and the second loading valve 32 can be controlled to be cut off, and the proportional valve can be controlled to be fully opened so that the two pumps are fully supplied with oil. Through the above control, the power unit 2 can be able to adjust its own flow output more finely according to different working conditions, so that it is more compatible with the flow rate required by the system, and only the second oil pump 22 with a smaller displacement will experience pressure loss during operation, which can also achieve the purpose of energy saving to a certain extent.

[0074] like Figure 1 As shown, the steering of aerial work machinery generally requires hydraulic assistance, and steering can generally be divided into front-wheel steering and four-wheel steering. Therefore, the execution unit 1 generally includes a front steering cylinder 12 and a rear steering cylinder 13. When performing front-wheel steering, the control unit is specifically configured as follows: Receive front wheel steering instructions; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump 21 is controlled to unload according to the small pump independent oil supply instruction, and the second oil pump 22 is controlled to supply oil.

[0075] When performing four-wheel steering, the control unit is specifically configured to: Receive four-wheel steering instructions; Generate a separate oil supply instruction for the large pump; In response to the large pump separate oil supply instruction, the first oil pump 21 is controlled to supply oil according to the four-wheel steering instruction, and the second oil pump 22 is controlled to unload.

[0076] The front wheel steering only requires the front steering cylinder 12 to move, and the required flow rate is relatively small. Therefore, only a small pump is required to meet the flow rate requirement of the front wheel steering. At this time, all the oil output by the first oil pump 21 is returned through the first unloading oil circuit, and the first oil pump 21 is idling and does not perform external work.

[0077] During four-wheel steering, the power unit 2 needs to supply oil to both the forward steering cylinder 12 and the rear steering cylinder 13 simultaneously, requiring a greater flow rate than that required for two-wheel steering. To ensure adequate oil supply to the power unit 2 during four-wheel steering, the first loading valve 31 can be closed and the second loading valve 32 can be opened. This allows the first oil pump 21 to supply oil to both the forward and rear steering cylinders 13 simultaneously, while the second oil pump 22 idles.

[0078] Furthermore, when the rated displacement of the first oil pump 21 is much larger than the flow required for four-wheel steering, the first loading valve 31 can also be set as a proportional valve to control the partial return oil of the first oil pump 21 to achieve fine-tuning of the flow delivered to the load end by the first oil pump 21.

[0079] like Figure 1 As shown, aerial work machinery generally spreads out its legs before working to increase the stability of the machinery. Aerial work machinery generally includes four side legs, and the leg driving cylinders of the four legs are respectively the left front leg cylinder 14, the left rear leg cylinder 15, the right front leg cylinder 16, and the right rear leg cylinder 17. Of course, some machines also include a fifth leg.

[0080] In order to adapt to different working environments, aerial work machinery generally has a mode in which the outriggers extend simultaneously, a mode in which the outriggers retract simultaneously, and a mode in which the outriggers extend and retract individually.

[0081] When multiple legs are extended simultaneously, the required flow rate is very large. In this case, the control unit can be configured as follows: Receive instructions for synchronous extension of outriggers; Generate dual pump common oil supply instruction; In response to the dual-pump common oil supply command, the first oil pump 21 and the second oil pump 22 are controlled to jointly supply oil according to the dual-pump common oil supply command.

[0082] The first oil pump 21 and the second oil pump 22 supply oil at full capacity to ensure that the legs can be extended quickly and synchronously.

[0083] When multiple legs need to be retracted synchronously, although the required flow rate is large, in order to avoid the legs from retracting too quickly and causing jamming, only the first oil pump 21 can be controlled to load, that is, the control unit is configured as follows: receiving a synchronous retraction instruction of the outriggers; Generate a separate oil supply instruction for the large pump; In response to the large pump independent oil supply instruction, the first oil pump 21 is controlled to supply oil according to the large pump independent oil supply instruction, and the second oil pump 22 is controlled to unload.

[0084] When the outriggers need to be retracted individually, the required flow rate is smaller. At this time, only the second oil pump 22 can be controlled to load. That is, after receiving the instruction for the individual extension and retraction of the outriggers, the control unit will control the first oil pump 21 to unload and control the second oil pump 22 to supply oil according to the instruction for the individual extension and retraction of the outriggers.

[0085] The working platform in some aerial work machines also has the function of extending and retracting to adapt to operations in some narrow areas, that is, the execution unit 1 also includes a platform telescopic cylinder 18.

[0086] When the work platform is extended or retracted, only one oil cylinder is working and the flow demand is relatively small. Therefore, after receiving the platform extension and retraction instruction, the control unit can control the first oil pump 21 to unload according to the platform extension and retraction instruction, and control the second oil pump 22 to supply oil alone.

[0087] like Figure 1 As shown, in this embodiment, a one-way check valve 41 is provided between the first oil pump 21 and the actuator unit 1 , and between the second oil pump 22 and the actuator unit 1 , to avoid oil cross-contamination.

[0088] like Figure 1 As shown, in this embodiment, a safety valve 42 may be further provided between the first oil pump 21 and the oil tank 43 , and between the second oil pump 22 and the oil tank 43 .

[0089] Some aerial work machinery also has a micro-motion function. The micro-motion requires very little flow. However, in this system, the first oil pump 21 and the second oil pump 22 have flow regulation performance that is much different from that of the variable pump when performing speed regulation. Therefore, when micro-motion action needs to be performed, the first oil pump 21 and the second oil pump 22 can operate at the rated speed and can also control the first loading valve 31 or the second loading valve 32 to be turned on and off separately in a time sequence, so that the first oil pump 21 or the second oil pump 22 can intermittently supply oil to the execution unit 1 separately. For example, when the front wheels are micro-steering, the second oil pump 22 can be controlled to supply oil intermittently. When the four wheels are micro-steering, the first oil pump 21 can be controlled to supply oil intermittently.

[0090] In this embodiment, when some actuator units 1 require inching, and each inching requires a large flow rate, the first loading valve 31 and the second loading valve 32 can be alternately controlled on and off in a timed sequence to allow the first oil pump 21 and the second oil pump 22 to alternately supply oil to the actuator units 1. If inching position adjustment is required when the legs are synchronously extended, the first oil pump 21 and the second oil pump 22 can be controlled to supply oil alternately.

[0091] To switch the oil supply mode of the power unit 2, in another embodiment of the present invention, a multi-way reversing valve may be provided between the power unit 2 and the actuator unit 1. The multi-way reversing valve selectively supplies the hydraulic oil output by the first oil pump 21 and the second oil pump 22 to the actuator unit 1 or the oil tank 43.

[0092] To achieve the above objectives, the present invention further provides a work machine, which may be an aerial work platform, a crane, an excavator, or other work equipment. The work machine includes the hydraulic control system described above. Because the work machine utilizes all of the technical solutions of the above embodiments, it at least possesses the beneficial effects of the above embodiments, and a detailed description thereof will not be repeated here.

[0093] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0094] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0095] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0096] Although the embodiments of the present invention have been described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A hydraulic control system for a working machine, characterized in that: The hydraulic control system of the working machine includes: a number of execution units (1); A power unit (2) comprising a first oil pump (21) and a second oil pump (22) for respectively supplying oil to the execution unit (1); A control unit for switching the oil supply mode of the power unit (2) according to a preset correspondence between "preset conditions-oil supply mode of the power unit" according to a target action to be performed by the operating machine; The oil supply method of the power unit (2) includes the first oil pump (21) and the second oil pump (22) supplying oil together, and one of the first oil pump (21) and the second oil pump (22) supplying oil alone.

2. The hydraulic control system for a working machine according to claim 1, characterized in that: The first oil pump (21) and the second oil pump (22) are double pumps and are respectively fixed-displacement pumps. The power unit (2) further comprises a driving element (23) for driving the first oil pump (21) and the second oil pump (22) to operate together. The high-efficiency speed range of the driving element (23) overlaps with the high-efficiency speed range of the correspondingly connected first oil pump (21) and / or second oil pump (22).

3. The hydraulic control system for a working machine according to claim 2, wherein: When the first oil pump (21) operates in the overlapping high-efficiency speed range, the flow rate required for operation of at least one of the pre-selected execution units (1) is within the output flow rate range of the first oil pump (21); and / or, when the second oil pump (22) operates in the overlapping high-efficiency speed range, the flow rate required for the operation of at least one of the pre-selected execution units (1) is within the output flow rate range of the second oil pump (22); And / or, when the first oil pump (21) and the second oil pump (22) operate in the overlapping high-efficiency speed range, the flow rate required for the operation of at least one of the pre-selected execution units (1) is within the range of the sum of the output flow rates of the first oil pump (21) and the second oil pump (22).

4. The hydraulic control system for a working machine according to claim 3, wherein: The overlapping high-efficiency speed range includes the peak-efficiency speed range of the drive element (23); When the first oil pump (21) operates in the peak efficiency speed range, the difference between the flow rate required for operation of at least one of the preselected execution units (1) and the output flow rate of the first oil pump (21) is less than a preset value; and / or, when the second oil pump (22) operates in the peak efficiency speed range, the difference between the flow rate required for operation of at least one of the preselected execution units (1) and the output flow rate of the second oil pump (22) is less than a preset value; and / or, when the first oil pump (21) and the second oil pump (22) operate in the peak efficiency speed range, the difference between the flow rate required for operation of at least one of the preselected execution units (1) and the sum of the output flow rates of the first oil pump (21) and the second oil pump (22) is less than a preset value; The control unit is further configured to control the driving element (23) to operate in the peak efficiency speed range when the pre-selected execution unit (1) is in operation.

5. The hydraulic control system for a working machine according to claim 3, characterized in that: The pre-selected execution unit (1) is the execution unit (1) whose startup probability is higher than a set threshold value according to big data analysis.

6. The hydraulic control system for a working machine according to claim 2, wherein: The driving element (23) is a motor or an engine.

7. The hydraulic control system for a working machine according to claim 1, wherein: A first unloading oil circuit is provided between the pumping port of the first oil pump (21) and the oil return circuit, the hydraulic control system further comprising an unloading switching unit (3), the unloading switching unit (3) comprising a first loading valve (31) for controlling the on-off of the first unloading oil circuit, a second unloading oil circuit is provided between the pumping port of the second oil pump (22) and the oil return circuit, the unloading switching unit (3) further comprising a second loading valve (32) for controlling the on-off of the second unloading oil circuit; The first loading valve (31) and the second loading valve (32) are switched on and off according to a preset correspondence between "preset conditions-oil supply mode of the power unit (2)" based on the target action to be performed by the operating machine.

8. The hydraulic control system for a working machine according to any one of claims 1 to 7, characterized in that: The displacement of the first oil pump (21) is greater than the displacement of the second oil pump (22).

9. The hydraulic control system for a working machine according to claim 8, characterized in that: The working machine is an aerial working machine, the plurality of execution units (1) include a lifting cylinder (11), the target action includes platform lifting, and the control unit is specifically configured as follows: Receive platform lifting instructions; Generate dual pump common oil supply instruction; In response to the dual-pump common oil supply instruction, the first oil pump (21) and the second oil pump (22) are controlled to supply oil together according to the dual-pump common oil supply instruction.

10. The hydraulic control system for a working machine according to claim 8, wherein: The working machine is an aerial working machine, the plurality of execution units (1) include a front steering cylinder (12), the target action includes front wheel steering, and the control unit is specifically configured as follows: Receive front wheel steering instructions; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump (21) is controlled to unload and the second oil pump (22) is controlled to supply oil according to the small pump independent oil supply instruction.

11. The hydraulic control system for a working machine according to claim 8, wherein: The working machine is an aerial working machine, the plurality of execution units (1) further include a rear steering cylinder (13), the target action includes four-wheel steering, and the control unit is specifically configured as follows: Receive four-wheel steering instructions; Generate a separate oil supply instruction for the large pump; In response to the large pump separate oil supply instruction, the first oil pump (21) is controlled to supply oil according to the four-wheel steering instruction, and the second oil pump (22) is controlled to unload.

12. The hydraulic control system for a working machine according to claim 8, wherein: The working machine is an aerial working machine, the plurality of execution units (1) include outrigger drive cylinders, the target actions include synchronous extension of the outriggers and synchronous retraction of the outriggers, and the control unit is specifically configured as follows: Receive instructions for synchronous extension of outriggers; Generate dual pump common oil supply instruction; In response to the dual-pump common oil supply instruction, controlling the first oil pump (21) and the second oil pump (22) to jointly supply oil according to the dual-pump common oil supply instruction; and / or; receiving a synchronous retraction instruction of the outriggers; Generate a separate oil supply instruction for the large pump; In response to the large pump independent oil supply instruction, the first oil pump (21) is controlled to supply oil and the second oil pump (22) is controlled to unload according to the large pump independent oil supply instruction.

13. The hydraulic control system for a working machine according to claim 8, wherein: The working machine is an aerial working machine, the plurality of execution units (1) include outrigger drive cylinders, the target action includes independent extension and retraction of the outriggers, and the control unit is specifically configured as follows: Receive instructions for extending and retracting the outriggers individually; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump (21) is controlled to unload and the second oil pump (22) is controlled to supply oil according to the small pump independent oil supply instruction.

14. The hydraulic control system for a working machine according to claim 8, wherein: The working machine is an aerial working machine, the plurality of execution units (1) include a platform telescopic oil cylinder (18), the target action includes platform telescopic movement, and the control unit is specifically configured as follows: Receive platform expansion and contraction instructions; Generate a separate oil supply instruction for the small pump; In response to the small pump independent oil supply instruction, the first oil pump (21) is controlled to unload and the second oil pump (22) is controlled to supply oil according to the small pump independent oil supply instruction.

15. A working machine, characterized in that: The working machine includes the hydraulic control system for a working machine according to any one of claims 1 to 14.

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