Work machine and hydraulic control system therefor

Abstract

The utility model belongs to operation machinery technical field and provides a kind of operation machinery and hydraulic control system thereof, and this system includes several execution units, power unit and control unit, power unit includes the first oil pump and the second oil pump for respectively to execution unit oil supply, first oil pump and the second oil pump are double pump, control unit is used to control first oil pump and the second oil pump respectively load oil supply or pressure relief oil return.This system can realize load flow matching at low cost by switching different oil supply modes at appropriate time.

Description

Technical Field

[0001] This utility model belongs to the field of work machinery technology, specifically relating to a hydraulic control system for work machinery and the work machinery itself. Background Technology

[0002] When operating machinery is in operation, different working conditions and different actions are performed, resulting in varying hydraulic flow requirements. For existing operating machinery, the main methods of hydraulic system flow control are valve control and pump control.

[0003] Valve-controlled systems refer to systems that control the flow rate of an oil pump to an actuator through electro-hydraulic proportional valves or servo valve assemblies. These systems offer high control precision, fast response, and good stability. However, to ensure control precision during operation, valve-controlled systems require the oil pump's flow rate output to exceed the actuator's required flow rate. This results in the pump's output power exceeding the actuator's power needs, and the excess power is wasted by the proportional valve or servo valve assemblies, leading to higher system energy consumption.

[0004] Pump control refers to using a variable pump for driving, which changes the pump's displacement to match the pump's output power with the power required by the load. Although this type of system can achieve lower energy consumption under the same action, variable pump servo control is complex and has a high construction cost, so it is difficult to popularize in the low-end and mid-range markets. Utility Model Content

[0005] In view of the above-mentioned defects or deficiencies, this utility model provides a hydraulic control system for aerial work machinery and the work machinery itself, aiming to solve the technical problem that the existing hydraulic control systems of aerial work machinery cannot simultaneously achieve low cost and low energy consumption.

[0006] To achieve the above objectives, this utility model provides a hydraulic control system for industrial machinery. The system includes several execution units, a power unit, and a control unit. The power unit includes a first oil pump and a second oil pump for supplying oil to the execution units respectively. The first oil pump and the second oil pump are a tandem pump. The control unit is used to control the first oil pump and the second oil pump to load oil supply or depressurize and return oil respectively.

[0007] In an embodiment of this utility model, a first unloading oil passage is provided between the pumping port of the first oil pump and the oil tank. The hydraulic control system further includes an unloading switching unit, which includes a first loading valve for controlling the on / off state of the first unloading oil passage. A second unloading oil passage is provided between the pumping port of the second oil pump and the oil tank. The unloading switching unit further includes a second loading valve for controlling the on / off state of the second unloading oil passage. The control unit is used to control the on / off state of the first loading valve and the second loading valve.

[0008] In an embodiment of this utility model, the first loading valve and / or the second loading valve are two-position two-way valves with a bidirectional flow valve position and a unidirectional flow valve position. The unidirectional flow valve position is configured to open when hydraulic oil flows from the oil tank to the system pressure oil circuit connected to the pump port and to close in the reverse direction.

[0009] In an embodiment of this utility model, a first overflow protection oil circuit is provided between the pumping port of the first oil pump and the oil tank, and a safety valve is provided on the first overflow protection oil circuit; and / or, a second overflow protection oil circuit is provided between the pumping port of the second oil pump and the oil tank, and a safety valve is provided on the second overflow protection oil circuit.

[0010] In an embodiment of this utility model, the power unit further includes a drive element for coaxially driving the first oil pump and the second oil pump, wherein the high-efficiency speed range of the drive element overlaps with the high-efficiency speed range of the connected first oil pump and the second oil pump.

[0011] In an embodiment of this utility model, when the first oil pump operates in overlapping high-efficiency speed ranges, the flow rate required for the operation of at least one of the actuators is within the output flow rate range of the first oil pump.

[0012] And / or, when the second oil pump operates in the overlapping high-efficiency speed range, the flow rate required for the operation of at least one of the actuators is within the output flow rate range of the second oil pump;

[0013] And / or, when the first oil pump and the second oil pump operate in overlapping high-efficiency speed ranges, the flow rate required for the operation of at least one of the actuators is within the range of the output flow rates of the first oil pump and the second oil pump.

[0014] In embodiments of this utility model, the driving element is a motor or an engine.

[0015] In embodiments of this utility model, the first oil pump and the second oil pump are fixed displacement pumps.

[0016] In an embodiment of this utility model, the displacement of the first oil pump is greater than that of the second oil pump.

[0017] To achieve the above objectives, this utility model also provides a working machine, wherein the working machine includes a hydraulic control system according to the above description.

[0018] Through the above technical solution, the hydraulic control system of the operating machinery provided by the present utility model embodiment has the following beneficial effects:

[0019] This system can select an appropriate oil supply method to match the flow rate based on the different actions performed by the actuator. For example, when the required flow rate of the action is large, the oil supply method of the first and second oil pumps can be changed, allowing the one with the larger displacement to supply oil alone, or allowing both pumps to supply oil together, thereby achieving a large flow rate output from the power unit. When the required flow rate of the action is small, the one with the smaller displacement can be controlled to supply oil alone, reducing the flow rate output of the power unit and avoiding excess flow waste. In this way, by switching the oil supply method of the power unit according to the different actions performed by the working machinery, the system's output flow rate can be made as close as possible to the required flow rate of the load, thereby reducing unnecessary energy waste and lowering system energy consumption to a certain extent. Moreover, this control method does not require the introduction of complex feedback mechanisms, making it very low-cost.

[0020] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] The accompanying drawings are provided to illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is a hydraulic schematic diagram of the hydraulic control system of the working machinery according to the embodiments of this utility model;

[0023] Figure 2 This is a control connection diagram of the hydraulic control system according to an embodiment of the present utility model.

[0024] Explanation of reference numerals in the attached figures

[0025] 1. Execution 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. Drive element; 3. Unloading switching unit; 31. First loading valve; 32. Second loading valve; 41. One-way check valve; 42. Safety valve; 43. Oil tank. Detailed Implementation

[0026] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0027] The hydraulic control system of the working machinery of this utility model is described below with reference to the accompanying drawings.

[0028] As the core of the drive and control of operating machinery, the hydraulic system accounts for a large portion of the overall construction cost. Reducing the component cost and energy consumption of the hydraulic system is of great significance for market expansion, especially for the low-to-mid-end market, where lower prices and lower energy consumption will make users more inclined to choose it.

[0029] Taking aerial work platforms as an example, aerial work platforms are equipment that lifts personnel or goods to a certain height for operation. They mainly consist of a vehicle body, boom, work platform, and hydraulic system.

[0030] When aerial work platforms are in operation, the required flow rate at the load end varies depending on the working conditions and the actions performed. To achieve matching control between system input and required flow rate within a limited cost, many existing aerial work platforms incorporate proportional valves or servo valve assemblies into their hydraulic systems. During operation, to ensure vehicle performance requirements, the pump unit outputs a constant flow rate. The flow rate entering the load end is adjusted through the proportional valves or servo valve assemblies to achieve high-performance operation of the actuators. However, with the pump unit outputting a constant flow rate, excess flow is throttled by the proportional valves or servo valve assemblies, resulting in wasted energy.

[0031] With the growing awareness of energy conservation and environmental protection, construction machinery is being improved in various ways to reduce the energy consumption of hydraulic systems. Pump control is one such mainstream improvement direction. By using variable displacement pumps with stepless speed regulation as pump sets, the output flow of the pump set can be matched with the flow required by the load by adjusting the pump set speed, which greatly reduces the operating energy consumption of the system.

[0032] However, variable pumps are much more expensive than ordinary fixed pumps, and the system also requires the introduction of a complex load feedback mechanism, making it difficult to popularize in the low-end and mid-range markets.

[0033] In view of this, the present invention discloses a hydraulic control system for a working machine, such as... Figure 1 As shown, the hydraulic control system includes several execution units 1, power units 2, and control units.

[0034] The power unit 2 includes a first oil pump 21 and a second oil pump 22 for supplying oil to the execution unit 1 respectively. The first oil pump 21 and the second oil pump 22 are a tandem pump.

[0035] The control unit is used to control the first oil pump 21 and the second oil pump 22 to load oil supply or depressurize and return oil respectively, so as to realize three oil supply modes: the first oil pump 21 and the second oil pump 22 supply oil together, or one of the first oil pump 21 and the second oil pump 22 supplies oil alone.

[0036] The control unit can be configured to switch the oil supply mode of the power unit 2 according to the preset correspondence between the "executed action - oil supply mode of power unit 2" based on the target action to be performed by the working machinery, so that the output flow of the system is as close as possible to the required flow of the load.

[0037] This system can select an appropriate oil supply method for flow matching based on the different actions performed by the execution unit 1. For example, when the required flow rate of the executed action is large, the oil supply method of the first oil pump 21 and the second oil pump 22 can be changed, allowing the one with the larger displacement of the first oil pump 21 and the second oil pump 22 to supply oil alone, or allowing the first oil pump 21 and the second oil pump 22 to supply oil together, thereby achieving a large flow output of the power unit 2. When the required flow rate of the executed action 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, thereby reducing the flow output of the power unit 2 and avoiding excess flow waste. In this way, by switching the oil supply method of the power unit 2 according to the different actions performed by the working machinery, the output flow rate of the system can be as close as possible to the required flow rate of the load, thereby reducing unnecessary energy waste of the system to a certain extent, reducing the system's energy consumption, and this control method does not require the introduction of a complex feedback mechanism, making it very low in cost.

[0038] Of course, the control unit can also switch the oil supply mode of the power unit 2 according to other conditions, such as pressure fluctuations of each execution unit 1, movement speed of each execution unit 1, and specific manual operation instructions received by the control unit.

[0039] In this embodiment, the first oil pump 21 and the second oil pump 22 can be fixed displacement pumps. The purchase price of ordinary fixed displacement pumps is much lower than that of variable displacement pumps. This system adopts a dual fixed displacement pump architecture and selects an appropriate oil supply strategy according to the working conditions. Under the premise of ensuring low cost, it solves to a certain extent the technical dilemma of "energy consumption and cost cannot be achieved simultaneously" in the hydraulic control system of existing aerial work machinery when matching flow.

[0040] like Figure 1 As shown, in this embodiment, in order to further reduce the cost of the power unit 2, the first oil pump 21 and the second oil pump 22 can be a tandem pump and share the same drive element 23. For example, the first oil pump 21 can be the front pump of the tandem pump, and the second oil pump can be the rear pump of the tandem pump.

[0041] To achieve the switching of the fuel supply mode for power unit 2, such as Figure 1 and Figure 2As shown, in one embodiment of this utility model, a first unloading oil passage is provided between the pumping port of the first oil pump 21 and the oil tank 43, and a second unloading oil passage is provided between the pumping port of the second oil pump 22 and the oil tank 43. A first loading valve 31 for controlling the on / off state is provided on the first unloading oil passage, and a second loading valve 32 for controlling the on / off state is provided on the second unloading oil passage. The unloading oil passage and the loading valves together constitute the unloading switching unit 3. The control unit is used to control the on / off state of the first loading valve 31 and the second loading valve 32.

[0042] When the first oil pump 21 and the second oil pump 22 need to supply oil together, the first loading valve 31 and the second loading valve 32 can both be switched to the shut-off state.

[0043] When only the first oil pump 21 needs to supply oil, the first loading valve 31 can be switched to the 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.

[0044] Similarly, when only the second oil pump 22 is needed to supply oil, the second loading valve 32 can be switched to the off state and the first loading valve 31 can be switched to the on state.

[0045] In this embodiment, the first loading valve 31 and / or the second loading valve 32 can each be a two-position two-way valve. This two-position two-way valve has a bidirectional flow position and a unidirectional flow position. The unidirectional flow position is configured to open when hydraulic oil flows from the oil tank 43 to the system pressure oil circuit connected to the pump port and to close in the reverse direction. By setting the unidirectional flow position, adaptive oil replenishment can be performed when the oil pump is loading and supplying oil, and the oil quantity in the system pressure oil circuit connected to the pump port is insufficient. Of course, the first loading valve 31 and / or the second loading valve 32 can also be other forms of directional valves with both a flow position and a stop position.

[0046] In this embodiment, a first overflow protection oil circuit is provided between the pumping port of the first oil pump 21 and the oil tank 43, and a safety valve 42 is provided on the first overflow protection oil circuit; and / or a second overflow protection oil circuit is provided between the pumping port of the second oil pump 22 and the oil tank 43, and a safety valve 42 is provided on the second overflow protection oil circuit. By setting the safety valve 42, overload of the system is avoided.

[0047] In this embodiment, the power unit 2 further includes a drive element 23 for coaxially driving the first oil pump 21 and the second oil pump 22. The high-efficiency speed range of the drive element 23 overlaps with the high-efficiency speed range of the connected first oil pump 21 and second oil pump 22. In other words, when selecting the first oil pump 21 and the second oil pump 22, by selecting the first oil pump 21 and the second oil pump 22 with suitable high-efficiency speed ranges, the operating speed of the drive element 23 can be matched, thereby ensuring the efficient operation of the power unit 2 and further reducing system energy consumption.

[0048] Specifically, taking the first oil pump 21 and the second oil pump 22 as a dual pump driven by a motor as an example, the high-efficiency speed range of the motor is assumed to be 2500-3500 rpm, while the first oil pump 21 and the second oil pump 22 can be selected with a high-efficiency speed range of 2400-3000 rpm. The overlapping high-efficiency speed range of the two is 2500-3000 rpm. When the motor runs in this overlapping high-efficiency speed range of 2500-3000 rpm, the pump also operates efficiently.

[0049] In this embodiment, the overlapping high-efficiency speed range preferably includes the peak high-efficiency speed of the drive element 23.

[0050] In this embodiment, after selecting the first oil pump 21 and the second oil pump 22 with 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.

[0051] Specifically, when selecting the displacement, the displacement parameters of the first oil pump 21 and the second oil pump 22 must meet at least one of the following conditions.

[0052] Condition 1: When the first oil pump 21 operates in the overlapping high-efficiency speed range, the output flow range of the first oil pump 21 includes at least the flow required for the operation of at least one of the pre-selected execution units 1;

[0053] Condition 2: When the second oil pump 22 operates in the overlapping high-efficiency speed range, the output flow range of the second oil pump 22 includes at least the flow required for the operation of at least one of the pre-selected actuators 1;

[0054] Condition 3: When the first oil pump 21 and the second oil pump 22 operate in overlapping high-efficiency speed ranges, the output flow rate of the first oil pump 21 and the range of the second oil pump 22 shall at least include the flow rate required for the operation of at least one of the pre-selected execution units 1.

[0055] Taking aerial work platform machinery as an example, the execution unit 1 of the aerial work platform machinery includes lifting cylinder 11, steering cylinder, outrigger drive cylinder, platform telescopic cylinder 18, etc. When the four sets of cylinders are working, it is assumed that their respective required displacements are 135L / min, 30L / min, 75L / min, and 50L / min.

[0056] Assuming the overlapping high-efficiency speed range is 2500-3000 rpm, the displacement of the first oil pump 21 can be selected as 27 ml / rpm. Correspondingly, the output flow rate range within the high-efficiency speed range is 27*(2500-3000) / 1000=67.5-81 L / min. This range includes the displacement of 75 L / min required when the outrigger drive cylinder is working. When the outrigger drive cylinder is working, by controlling the first oil pump 21 to supply oil independently, the system can generate a maximum flow waste of only 6 L / min, effectively reducing the system's energy consumption.

[0057] Furthermore, the displacement of the second oil pump 22 can be selected as 18 ml / rpm, which corresponds to an output flow range of 45-54 L / min, encompassing the 50 L / min displacement required when the platform telescopic cylinder 18 is working. The combined maximum displacement of the first oil pump 21 and the second oil pump 22 is exactly 81 + 54 = 135 L / min. When the lifting cylinder 11 needs to work, by controlling the two pumps to supply oil together, the system flow rate can be made to match the flow rate required by the load during lifting.

[0058] It is understandable that the specific values ​​mentioned above are just an example. In actual products, the displacement of the first oil pump 21 and the second oil pump 22 can be adapted to different product models.

[0059] In this embodiment, the pre-selected execution unit 1 is the execution unit 1 whose power-on probability is higher than a set threshold based on big data analysis. That is, when the first oil pump 21 and the second oil pump 22 are selecting displacement, the execution unit 1 with the higher usage frequency is given priority.

[0060] Continuing with the example of aerial work platforms, according to big data analysis, when users operate aerial work platforms, the probability of using the outrigger extension 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 cylinder 18 are 110L / min, 40L / min, 70L / min, and 60L / min respectively, and the overlapping high-efficiency speed range is 2500-3000rpm, then 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 rate adjustment range within 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 rate adjustment range within the high-efficiency speed range is 37.5-45L / min) can be selected as the second oil pump 22.

[0061] 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, so as to generate a flow rate of up to 120L / min to match the flow rate requirements of the platform lifting.

[0062] 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 rate requirement of 70L / min when the outriggers extend or retract.

[0063] When used for steering, the power unit 2 can select the second oil pump 22 to supply oil separately to match the 40L / min flow requirement of the steering cylinder.

[0064] By matching the displacement of the first oil pump 21 and the second oil pump 22, the aerial work platform is in a state of good flow load matching most of the time. Only when the user needs to perform some less frequently used operations will the flow matching adjustment effect occasionally appear in the overlapping high-efficiency speed range.

[0065] In this embodiment, parameters such as the high-efficiency operating range of the oil pump and drive element 23, and the pump displacement can be further selected so that the drive element 23 operates at peak efficiency under the main operating conditions, and the drive element 23 and pump operate efficiently under other operating conditions.

[0066] Assuming the peak efficient operating speed of the motor is 2800 rpm, according to big data analysis, outrigger extension and platform lifting are used more than 90% of the time during the operation of the aerial work platform. Therefore, outrigger extension and platform lifting can be defined as the main operating conditions of the aerial work platform. By selecting oil pumps with displacements of 25 ml / rpm and 15 ml / rpm respectively, when the user needs to extend the outrigger or lift the platform, by controlling the drive element 23 to operate at 2800 rpm and controlling the first oil pump to supply oil alone or both pumps to supply oil together, the required flow rate of 70 L / min during outrigger extension and the required flow rate of 110 L / min during lifting cylinder 11 can be matched respectively, resulting in a flow rate redundancy of less than 2%. When the aerial work platform is performing other actions, by controlling the speed of the drive element 23 to be adjusted within the efficient speed range of 2500-2800 rpm, the entire system will still be in a state of roughly matched flow rate and efficient operation of power unit 2.

[0067] In this embodiment, the drive element 23 can be a motor or an engine.

[0068] Continuing with the example of aerial work platforms, such as Figure 1 As shown, the execution unit 1 of the aerial work platform can include a lifting cylinder 11. When the aerial work platform needs to be lifted, the operator will press the lifting button to generate a platform lifting command. After receiving the platform lifting command, the control unit will not only control the control valve group of the lifting cylinder 11 to operate, but also respond to the platform lifting command and control the first oil pump 21 and the second oil pump 22 to supply oil together according to the platform lifting command.

[0069] The tandem pump system preferably consists of two pumps, one with a larger displacement and the other with a smaller displacement. The larger pump is typically used when the system requires a higher flow rate, while the smaller pump is mainly used for low-flow oil supply or auxiliary oil supply. When neither pump is loaded, they run idle, and the system's energy consumption is only the power consumed by the larger and smaller pumps during idle operation.

[0070] Taking the first oil pump 21 as an example, when the platform is lifted, in order to ensure that the platform has sufficient lifting force and lifting speed, the system requires a relatively large flow rate, which generally exceeds the rated maximum displacement of the first oil pump 21. Therefore, in order to ensure that the lifting cylinder 11 can complete its action smoothly, after receiving the platform lifting command, the control unit can generate a dual-pump joint oil supply command, and control the first loading valve 31 and the second loading valve 32 to be shut off according to the dual-pump joint oil supply command, so that the first oil pump 21 and the second oil pump 22 jointly supply oil to the lifting cylinder 11, ensuring the driving force and extension speed of the lifting cylinder 11.

[0071] Some aerial work platforms may have two operating modes: rapid lifting and energy-saving lifting. The flow rate required for the lifting cylinder 11 differs between these two modes. Therefore, in this embodiment, a proportional valve can be installed between the second oil pump 22 and the execution unit 1. During smooth lifting, the proportional valve is controlled to open proportionally, allowing the first oil pump 21 to supply oil at full capacity and the second oil pump 22 to supply oil partially, achieving a smooth and slow lifting of the platform. When the platform carries a large load or requires a faster lifting speed, both the first loading valve 31 and the second loading valve 32 can be shut off, and the proportional valve can be fully opened, allowing both pumps to supply oil at full capacity. Through this control, the power unit 2 can more precisely adjust its flow output according to different working conditions, making it more compatible with the system's required flow rate. Furthermore, only the second oil pump 22, with its smaller displacement, experiences pressure loss during operation, which also achieves energy saving to some extent.

[0072] like Figure 1 As shown, the steering of aerial work platforms generally relies on hydraulic power, and steering can generally be divided into front-wheel steering and four-wheel steering. Therefore, the actuator 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:

[0073] Receive front wheel steering commands;

[0074] Generate a separate oil supply command for the small pump;

[0075] In response to the small pump's individual oil supply command, the first oil pump 21 is unloaded and the second oil pump 22 is controlled to supply oil according to the small pump's individual oil supply command.

[0076] When performing four-wheel steering, the control unit is specifically configured as follows:

[0077] Receive four-wheel steering commands;

[0078] Generate a separate oil supply command for the large pump;

[0079] In response to the single oil supply command of the large pump, the first oil pump 21 is controlled to supply oil according to the four-wheel steering command, and the second oil pump 22 is controlled to unload.

[0080] The front wheel steering only requires the front steering cylinder 12 to be activated, which requires a small flow rate. Therefore, only the small pump needs to work to meet the flow rate requirements of the front wheel steering. At this time, all the oil output by the first oil pump 21 returns through the first unloading oil circuit. The first oil pump 21 runs idle and does not perform any external work.

[0081] When four wheels are turned, the power unit 2 needs to supply oil to both the forward steering cylinder 12 and the rear steering cylinder 13 simultaneously, so the required flow rate is greater than that required when turning two wheels. In order to ensure sufficient oil supply to the power unit 2 during four-wheel steering, a strategy of shutting off the first loading valve 31 and opening the second loading valve 32 can be adopted, so that the first oil pump 21 supplies oil to both the forward and rear steering cylinders 13 simultaneously, while the second oil pump 22 idles.

[0082] Furthermore, when the rated displacement of the first oil pump 21 is much greater than the flow rate required for four-wheel steering, the first loading valve 31 can be set as a proportional valve, and the flow rate of the first oil pump 21 to the load end can be finely adjusted by controlling part of the return oil of the first oil pump 21.

[0083] like Figure 1 As shown, before working, aerial work platforms typically extend their outriggers to increase stability. Aerial work platforms generally include four side outriggers, and the outrigger drive cylinders for the four outriggers are: left front outrigger cylinder 14, left rear outrigger cylinder 15, right front outrigger cylinder 16, and right rear outrigger cylinder 17. Of course, some machines may also include a fifth outrigger.

[0084] To adapt to different working environments, aerial work platforms generally have modes such as simultaneous outrigger extension, simultaneous outrigger retraction, and individual outrigger extension / retraction.

[0085] When multiple outriggers extend simultaneously, the required flow rate is very large. In this case, the control unit can be configured as follows:

[0086] Receive commands to synchronously extend the outriggers;

[0087] Generate a command for dual-pump joint oil supply;

[0088] In response to the dual-pump joint oil supply command, the first oil pump 21 and the second oil pump 22 are controlled to supply oil together according to the dual-pump joint oil supply command.

[0089] By fully supplying oil to the first oil pump 21 and the second oil pump 22, the outriggers can be extended quickly and synchronously.

[0090] When multiple outriggers need to retract synchronously, although the required flow rate is large, to avoid the outriggers retracting too quickly and causing jamming, only the first oil pump 21 can be controlled to operate. That is, the control unit is configured as follows:

[0091] Receive outrigger synchronous retraction command;

[0092] Generate a separate oil supply command for the large pump;

[0093] In response to the single oil supply command of the main pump, the first oil pump 21 is controlled to supply oil, and the second oil pump 22 is controlled to unload.

[0094] When the outrigger needs to retract individually, the required flow rate is small. At this time, only the second oil pump 22 can be controlled to be loaded. That is, after receiving the command for the outrigger to extend or retract individually, 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 command for the outrigger to extend or retract individually.

[0095] Some aerial work platforms also have the function of extending and retracting to adapt to operations in some narrow areas. That is, the execution unit 1 also includes the platform telescopic cylinder 18.

[0096] When the work platform extends or retracts, only one hydraulic cylinder works, and the demand for flow rate is small. Therefore, after receiving the platform extension and retraction command, the control unit can control the first hydraulic pump 21 to unload and control the second hydraulic pump 22 to supply oil separately.

[0097] like Figure 1 As shown, in this embodiment, a one-way check valve 41 is provided between the first oil pump 21 and the execution unit 1, and between the second oil pump 22 and the execution unit 1, to prevent oil cross-contamination.

[0098] Some aerial work platforms also have a micro-motion function. Micro-motion requires very little flow. However, the flow regulation performance of the first oil pump 21 and the second oil pump 22 in this system is much worse than that of a variable pump when adjusting the speed. Therefore, when micro-motion is required, the first oil pump 21 and the second oil pump 22 can also control the opening and closing of the first loading valve 31 or the second loading valve 32 in sequence under the premise of operating at rated speed, so that the first oil pump 21 or the second oil pump 22 can supply oil to the execution unit 1 intermittently. For example, when the front wheels are micro-steering, the second oil pump 22 can be controlled to supply oil intermittently, and when the four wheels are micro-steering, the first oil pump 21 can be controlled to supply oil intermittently.

[0099] In this embodiment, when some of the execution units 1 require micro-motion, and each micro-motion requires a large flow rate, the first loading valve 31 and the second loading valve 32 can be controlled alternately in sequence to allow the first oil pump 21 and the second oil pump 22 to alternately supply oil to the execution unit 1. If micro-motion adjustment is required when the outriggers extend synchronously, the first oil pump 21 and the second oil pump 22 can be controlled to alternately supply oil.

[0100] To enable switching of the oil supply mode for the power unit 2, in another embodiment of this invention, a multi-way directional valve can be provided between the power unit 2 and the execution unit 1. Through the multi-way directional valve, the hydraulic oil output from the first oil pump 21 and the second oil pump 22 can be selectively supplied to the execution unit 1 or the oil tank 43.

[0101] To achieve the above objectives, this utility model also provides a working machine, which can be an aerial work platform, crane, excavator, or other working equipment. The working machine includes the hydraulic control system described above. Since the working machine adopts all the technical solutions of the above embodiments, it at least possesses the beneficial effects brought about by the above embodiments, and will not be repeated here.

[0102] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0103] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0104] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0105] Although embodiments of the present invention have been described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic control system for a work machinery, characterized in that, The hydraulic control system of the operating machinery includes: Several execution units (1); The power unit (2) includes a first oil pump (21) and a second oil pump (22) for supplying oil to the execution unit (1) respectively, wherein the first oil pump (21) and the second oil pump (22) are a tandem pump; The control unit is used to control the first oil pump (21) and the second oil pump (22) to load oil supply or depressurize and return oil respectively.

2. The hydraulic control system of the operating machinery according to claim 1, characterized in that, A first unloading oil circuit is provided between the pumping port of the first oil pump (21) and the oil tank (43). The hydraulic control system also includes an unloading switching unit (3). The unloading switching unit (3) includes a first loading valve (31) for controlling the opening and closing 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 tank (43). The unloading switching unit (3) also includes a second loading valve (32) for controlling the opening and closing of the second unloading oil circuit. The control unit is used to control the opening and closing of the first loading valve (31) and the second loading valve (32).

3. The hydraulic control system of the operating machinery according to claim 2, characterized in that, The first loading valve (31) and / or the second loading valve (32) are two-position two-way valves with a bidirectional and a unidirectional valve position. The unidirectional valve position is configured to open when hydraulic oil flows from the oil tank (43) to the system pressure oil circuit connected to the pump port and to close in the reverse direction.

4. The hydraulic control system of the operating machinery according to claim 2, characterized in that, A first overflow protection oil circuit is also provided between the pumping port of the first oil pump (21) and the oil tank (43), and a safety valve (42) is provided on the first overflow protection oil circuit; and / or A second overflow protection oil circuit is provided between the pumping port of the second oil pump (22) and the oil tank (43), and a safety valve (42) is provided on the second overflow protection oil circuit.

5. The hydraulic control system of the operating machinery according to claim 1, characterized in that, The power unit (2) also includes a drive element (23) for coaxially driving the first oil pump (21) and the second oil pump (22). The high-efficiency speed range of the drive element (23) overlaps with the high-efficiency speed range of the connected first oil pump (21) and the second oil pump (22).

6. The hydraulic control system of the operating machinery according to claim 5, characterized in that, 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 of the actuators (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 actuators (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 actuators (1) is within the range of the combined output flow rates of the first oil pump (21) and the second oil pump (22).

7. The hydraulic control system of the operating machinery according to claim 6, characterized in that, The drive element (23) is a motor or engine.

8. The hydraulic control system of the operating machinery according to any one of claims 1 to 7, characterized in that, The first oil pump (21) and the second oil pump (22) are fixed displacement pumps.

9. The hydraulic control system of the operating machinery according to any one of claims 1 to 7, characterized in that, The displacement of the first oil pump (21) is greater than that of the second oil pump (22).

10. A type of operating machinery, characterized in that, The operating machinery includes a hydraulic control system for the operating machinery according to any one of claims 1 to 9.

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