Hydraulic control system and method and aerial work platform

Abstract

The invention discloses a hydraulic control system and method and an aerial work platform, and relates to the field of hydraulic control. The system comprises a control unit, a power unit and functional loops, the power unit comprises an adjustable-speed motor and an electro-hydraulic proportioning pump driven by the adjustable-speed motor; the control unit is used for controlling the outlet flow of the electro-hydraulic proportioning pump according to the expected flow; the real-time total efficiency of the power unit is determined according to the real-time torque of the speed regulating motor and the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportioning pump; and the rotating speed of the speed regulating motor and the displacement of the electro-hydraulic proportioning pump are controlled in real time by taking the highest real-time total efficiency of the power unit as a target. The problem that the total efficiency of the aerial work platform motor and the hydraulic pump is difficult to reach the highest is solved, the system energy loss is reduced, and the cruising ability of the aerial work platform battery is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic control, and in particular relates to a hydraulic control system, method and aerial work platform. Background Art

[0002] Aerial work platform is a kind of equipment used for aerial work, which is widely used in construction, electricity, municipal engineering and other fields. The main components of its hydraulic control system are: power unit, amplitude change circuit, telescopic circuit, turntable circuit, leveling circuit, flying arm circuit, work bar swing circuit, steering circuit and floating circuit. The existing electrification transformation plan of aerial work platform is to replace the engine with an electric motor, and the control system still uses the load sensitive system. This plan fails to effectively solve the problem of large throttling loss of valve control system, and the motor runs at a fixed speed, causing the hydraulic pump to be in a small displacement area under some working conditions, and the hydraulic pump efficiency is low. Taking a 28-meter aerial work platform as an example, the energy loss of the motor, hydraulic pump and multi-way valve are 23%, 25% and 9% respectively. The large amount of energy loss seriously affects the endurance of the aerial work platform.

[0003] At present, the load-sensitive control system widely used in aerial work platforms has the following main defects:

[0004] ① The motor speed is fixed and will not be controlled in real time. If the required flow is too large and exceeds the limit of the pump, the flow supply of the hydraulic control system cannot be guaranteed;

[0005] ② The efficiency of the motor and pump is low under certain working conditions. The main performances are: the motor runs at a fixed speed. Under partial load and no-load conditions, the motor efficiency is low; under low flow conditions, the pump is often in the small displacement area, and the hydraulic pump efficiency is low;

[0006] ③ It is difficult for the total efficiency of the motor and pump to always remain at the highest level under different working conditions: Because the pressure and flow of the hydraulic system are constantly changing, the efficiency of the pump and motor is constantly changing, which makes it difficult for the total efficiency of the two to always remain at the highest level under different working conditions;

[0007] ④ Because the load-sensitive system requires a pressure difference to adjust the pump outlet flow, throttling energy loss is inevitable.

[0008] Therefore, considering using a speed-regulating motor to drive an electro-hydraulic proportional pump as an electro-hydraulic power source can basically eliminate the throttling loss of the hydraulic system. By constantly adjusting the motor speed and pump displacement, the efficiency of the hydraulic system can be kept at the highest level under different working conditions, thereby improving the energy utilization efficiency of the hydraulic system as a whole. This is also an idea for further improving the energy-saving potential of the hydraulic system under the variable speed and variable displacement control mode. Summary of the invention

[0009] The object of the present invention is to provide a hydraulic control system, method and aerial work platform to solve the problem of low efficiency of motors and pumps in traditional load-sensitive control systems and throttling energy loss caused by the need for a pressure difference to adjust the pump outlet flow.

[0010] The present invention solves the above technical problems through the following technical solutions: a hydraulic control system, comprising a control unit, a power unit and various functional circuits; the power unit comprises a speed regulating motor and an electro-hydraulic proportional pump driven by the speed regulating motor; the functional circuits comprise a floating circuit, a luffing circuit, a telescopic circuit, a turntable circuit, a leveling circuit and a steering circuit; the oil outlet of the electro-hydraulic proportional pump is connected to the main valve components in the floating circuit, the luffing circuit, the telescopic circuit, the turntable circuit, the leveling circuit and the steering circuit;

[0011] The control unit is used to control the outlet flow of the electro-hydraulic proportional pump according to the expected flow; determine the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor, the real-time outlet pressure of the electro-hydraulic proportional pump and the real-time outlet flow; and control the speed of the speed regulating motor and the displacement of the electro-hydraulic proportional pump in real time with the goal of maximizing the real-time total efficiency of the power unit.

[0012] Furthermore, the floating circuit includes a first reversing valve, a first shuttle valve, a pressure reducing valve, a second reversing valve, a floating multi-way valve, a two-way balancing valve and a floating oil cylinder; the oil inlet of the first reversing valve and the oil inlet of the pressure reducing valve are respectively connected to the oil outlet of the electro-hydraulic proportional pump, the oil outlet of the first reversing valve and the oil drain port of the pressure reducing valve are respectively connected to the hydraulic oil tank, the control oil port of the first reversing valve is connected to the oil outlet of the pressure reducing valve and the oil inlet of the second reversing valve through the first shuttle valve, the first shuttle valve is also connected to the amplitude variation circuit, the telescopic circuit, the turntable circuit, the leveling circuit and the steering circuit; the oil outlet of the second reversing valve is connected to the two-way balancing valve through the floating multi-way valve, and the two-way balancing valve is connected to the floating oil cylinder.

[0013] Furthermore, a throttling device is provided in the oil circuit between the pressure reducing valve and the second reversing valve, and the throttling device is a fixed throttling hole or a variable throttling hole.

[0014] Furthermore, a filter is provided at the oil outlet of the electro-hydraulic proportional pump.

[0015] Furthermore, a one-way valve is provided at the oil inlet of the amplitude variation circuit.

[0016] Further, the amplitude variation circuit includes a main valve assembly, a switching valve, a proportional throttle valve and an amplitude variation cylinder, the oil inlet of the main valve assembly is connected to the oil outlet of the electro-hydraulic proportional pump, the control oil port of the main valve assembly is connected to the first shuttle valve in the floating circuit, and the oil outlet of the main valve assembly is connected to the amplitude variation cylinder; a switching valve is provided on the oil circuit between the main valve assembly and the rodless chamber of the amplitude variation cylinder, the first end of the proportional throttle valve is connected to the oil circuit between the main valve assembly and the rodless chamber of the amplitude variation cylinder, and the second end of the proportional throttle valve is connected to the oil circuit between the main valve assembly and the rod chamber of the amplitude variation cylinder.

[0017] Further, the main valve assembly includes a pressure compensating valve, a variable amplitude multi-way valve, a second shuttle valve and a third shuttle valve, the oil inlet of the pressure compensating valve is connected to the oil outlet of the electro-hydraulic proportional pump, the control oil port of the pressure compensating valve is connected to the first shuttle valve in the floating circuit through the second shuttle valve, the oil outlet of the pressure compensating valve is connected to the first port of the variable amplitude multi-way valve, the second port and the third port of the variable amplitude multi-way valve serve as the oil outlet of the main valve assembly; the two ends of the third shuttle valve are respectively connected to the second port of the variable amplitude multi-way valve, and the third shuttle valve is also connected to the second shuttle valve.

[0018] Furthermore, the main valve assembly includes a cartridge valve and a third reversing valve, the oil inlet of the cartridge valve is connected to the oil outlet of the electro-hydraulic proportional pump, the oil outlet of the cartridge valve is connected to the first port of the third reversing valve, the second port and the third port of the third reversing valve serve as the oil outlet of the main valve assembly; the fourth port of the third reversing valve is connected to the hydraulic oil tank; the first shuttle valve in the floating circuit is connected to the oil outlet of the cartridge valve, the telescopic circuit, the turntable circuit, the leveling circuit and the steering circuit.

[0019] Based on the same concept, the present invention also provides a hydraulic control method, which is applied to the hydraulic control system as described above, and the control method comprises:

[0020] Control the outlet flow of the electro-hydraulic proportional pump according to the desired flow;

[0021] Obtain the real-time torque of the speed regulating motor, the real-time outlet pressure and real-time outlet flow of the electro-hydraulic proportional pump;

[0022] Determine the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump;

[0023] The speed of the speed regulating motor and the displacement of the electro-hydraulic proportional pump are controlled in real time with the goal of maximizing the real-time overall efficiency of the power unit.

[0024] Based on the same concept, the present invention also provides an aerial work platform, including the hydraulic control system as described above.

[0025] Beneficial Effects

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] The hydraulic control system of the present invention is based on a speed-regulating motor and an electro-hydraulic proportional pump, and realizes the joint regulation of the motor speed and the pump displacement under different flow rates and pressures through a control unit, thereby improving the efficiency of the speed-regulating motor and the electro-hydraulic proportional pump while ensuring the flow rate required for the actual working condition, solving the throttling loss caused by the need for a pressure difference to adjust the output flow rate of the traditional load-sensitive pump, and the difficulty in always maintaining the highest total efficiency of the motor and the pump under different working conditions, thereby reducing the energy loss of the system. In order to adapt to the improvement of the power unit of the present invention, the traditional floating circuit of the aerial work platform is improved so that the floating circuit has a constant pressure standby function at the pump outlet, meeting the performance requirements of rapid floating and leveling during walking conditions, and solving the problem that the traditional floating circuit cannot achieve constant pressure standby or the standby pressure is too high when it is directly used in the new hydraulic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of a hydraulic control system in which a multi-way valve is used in a functional circuit in an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of a hydraulic control system in which a functional circuit adopts a cartridge valve in an embodiment of the present invention.

[0031] Explanation of the accompanying drawings: 1-speed regulating motor, 2-electro-hydraulic proportional pump, 3-filter, 10-floating circuit, 11-first reversing valve, 12-first shuttle valve, 13-pressure reducing valve, 14-throttling device, 15-second reversing valve, 16-floating multi-way valve, 17-floating cylinder, 18-two-way balancing valve, 20-amplitude changing circuit, 21-amplitude changing multi-way valve, 22-third shuttle valve, 23-second shuttle valve, 24-switch valve, 25-proportional throttle valve, 26-amplitude changing cylinder, 27-cartridge valve, 28-third reversing valve, 29-pressure compensating valve, 30-telescopic circuit, 40-turntable circuit, 50-leveling circuit, 60-flying arm circuit, 70-swing circuit, 80-steering circuit. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solution in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The technical solution of the present application is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0034] Embodiment 1

[0035] In order to solve the problem that the load-sensitive control system used in aerial work platforms has low efficiency of motors and pumps and requires a pressure difference to adjust the pump outlet flow rate, resulting in throttling energy loss, the present invention provides a hydraulic control system. Figure 1 and Figure 2 As shown, the hydraulic control system includes a control unit, a power unit and various functional circuits; the power unit includes a speed regulating motor 1 and an electro-hydraulic proportional pump 2 driven by the speed regulating motor 1; the functional circuits include a floating circuit 10, a variable amplitude circuit 20, a telescopic circuit 30, a turntable circuit 40, a leveling circuit 50, a flying arm circuit 60, a swing circuit 70 and a steering circuit 80; the oil outlet of the electro-hydraulic proportional pump 2 is connected to the main valve components in the floating circuit 10, the variable amplitude circuit 20, the telescopic circuit 30, the turntable circuit 40, the leveling circuit 50 and the steering circuit 80, and the flying arm circuit 60 and the swing circuit 70 are respectively connected to the leveling circuit 50. The control unit controls the outlet flow of the electro-hydraulic proportional pump 2 according to the expected flow; determines the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor 1, the real-time outlet pressure of the electro-hydraulic proportional pump 2 and the real-time outlet flow; and controls the speed of the speed regulating motor 1 in real time with the goal of maximizing the real-time total efficiency of the power unit.

[0036] The real-time total efficiency of the power unit is equal to the product of the real-time efficiency of the speed regulating motor 1 and the real-time efficiency of the electro-hydraulic proportional pump 2. When the outlet flow of the electro-hydraulic proportional pump 2 is controlled according to the desired flow, the real-time torque of the speed regulating motor 1, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump 2 can be obtained. The real-time efficiency of the electro-hydraulic proportional pump 2 can be determined according to the real-time outlet pressure and the real-time outlet flow, and the real-time efficiency of the speed regulating motor 1 can be determined according to the real-time torque, and then the real-time total efficiency of the power unit can be obtained. The speed of the speed regulating motor 1 is controlled in real time with the goal of maximizing the real-time total efficiency of the power unit, and the joint regulation of the speed of the speed of the speed regulating motor 1 and the displacement of the electro-hydraulic proportional pump 2 is realized. The efficiency of the speed regulating motor 1 and the electro-hydraulic proportional pump 2 is improved while ensuring the flow required for the actual working condition, and the throttling loss caused by the traditional load-sensitive control system that requires a pressure difference to adjust the output flow is solved, thereby reducing the energy loss of the system.

[0037] In this embodiment, the speed regulating motor 1 adopts a three-phase asynchronous motor, and the speed control mode of the speed regulating motor 1 is vector control, which can make the control performance of the AC asynchronous motor close to that of the DC motor. The output flow of the electro-hydraulic proportional pump 2 can be controlled by the electrical signal output by the operating handle, and the flow of the hydraulic control system can be accurately controlled by adjusting the speed of the speed regulating motor 1 and the output flow of the electro-hydraulic proportional pump 2, thereby increasing the flow controllable range, solving the problem that the system flow supply cannot be guaranteed due to the fixed motor speed, and improving the energy utilization efficiency.

[0038] By jointly regulating the speed of the speed regulating motor 1 and the displacement of the electro-hydraulic proportional pump 2, the power matching of the speed regulating motor 1 and the electro-hydraulic proportional pump 2 is achieved. For example, when idling and no-load, the speed of the speed regulating motor 1 is reduced to reduce its output power and reduce energy loss; under low flow conditions, the output flow of the electro-hydraulic proportional pump 2 is increased to avoid it working in a small displacement area, thereby improving the working efficiency of the electro-hydraulic proportional pump 2 and improving the overall efficiency of the power unit.

[0039] The floating circuit 10 based on the load-sensitive pump cannot form back pressure, resulting in the inability to achieve the floating function. Therefore, the present invention improves the floating circuit 10 to adapt to the power unit of the speed regulating motor 1 + the electro-hydraulic proportional pump 2 to achieve floating control.

[0040] like Figure 1 and Figure 2As shown, the floating circuit 10 includes a first reversing valve 11, a first shuttle valve 12, a pressure reducing valve 13, a second reversing valve 15, a floating multi-way valve 16, a two-way balancing valve 18 and a floating oil cylinder 17; the oil inlet of the first reversing valve 11 and the oil inlet of the pressure reducing valve 13 are respectively connected to the oil outlet of the electro-hydraulic proportional pump 2, the oil outlet of the first reversing valve 11 and the oil drain port of the pressure reducing valve 13 are respectively connected to the hydraulic oil tank, the control oil port of the first reversing valve 11 is connected to the oil outlet of the pressure reducing valve 13 and the oil inlet of the second reversing valve 15 through the first shuttle valve 12, the first shuttle valve 12 is also connected to the amplitude changing circuit 20, the telescopic circuit 30, the turntable circuit 40, the leveling circuit 50 and the steering circuit 80; the oil outlet of the second reversing valve 15 is connected to the two-way balancing valve 18 through the floating multi-way valve 16, and the two-way balancing valve 18 is connected to the floating oil cylinder 17. In this embodiment, the first reversing valve 11 is a two-position two-way reversing valve.

[0041] When the system is idling, the output flow of the electro-hydraulic proportional pump 2 flows into the hydraulic oil tank through the pressure reducing valve 13, and the output flow of the electro-hydraulic proportional pump 2 is greater than the internal leakage of the electro-hydraulic proportional pump 2 to meet the internal leakage of the electro-hydraulic proportional pump 2, and the excess flow flows into the hydraulic oil tank through the pressure reducing valve 13.

[0042] When the system is in walking and floating condition, the output flow of the electro-hydraulic proportional pump 2 is divided into two paths: one path flows to the oil inlet of the first reversing valve 11, and the other path is divided into two paths after passing through the pressure reducing valve 13: one path enters the floating oil cylinder 17 through the second reversing valve 15, the floating multi-way valve 16 and the two-way balance valve 18, and the other path acts on the control oil port of the first reversing valve 11 through the first shuttle valve 12; the opening condition of the first reversing valve 11 is: the outlet pressure of the electro-hydraulic proportional pump 2 is greater than or equal to the control oil port pressure and the spring force, for example, the output pressure of the pressure reducing valve 13 is 45bar, and the spring force is 32bar, then the opening pressure of the first reversing valve 11 is 77bar. After the walking and floating instruction is output, the outlet pressure of the electro-hydraulic proportional pump 2 is constant as the sum of the output pressure of the pressure reducing valve 13 and the spring force, and the oil inlet pressure of the floating multi-way valve 16 is constant as the output pressure of the pressure reducing valve 13. When the external load or terrain changes, the hydraulic oil quickly enters the floating oil cylinder 17, so that it can be fine-tuned in the floating state to keep the vehicle body stable, that is, constant pressure standby, and realize back pressure. After the first reversing valve 11 is opened, if the floating cylinder 17 has a flow demand, the flow will flow to the floating cylinder 17, and the excess flow will be released through the first reversing valve 11; if there is no floating response, the fixed flow of the electro-hydraulic proportional pump 2 will all be released through the first reversing valve 11.

[0043] In a specific embodiment of the present invention, a throttle 14 is further provided in the oil circuit between the pressure reducing valve 13 and the second reversing valve 15. The throttle 14 is a fixed throttle hole or a variable throttle hole to achieve flow regulation.

[0044] In a specific embodiment of the present invention, a filter 3 is further provided at the oil outlet of the electro-hydraulic proportional pump 2, and impurities in the oil are filtered out by the filter 3.

[0045] In a specific embodiment of the present invention, Figure 1 and Figure 2 As shown, the amplitude changing circuit 20 includes a main valve assembly, a switch valve 24, a proportional throttle valve 25 and an amplitude changing oil cylinder 26. The oil inlet of the main valve assembly is connected to the oil outlet of the electro-hydraulic proportional pump 2, the control oil port of the main valve assembly is connected to the first shuttle valve 12 in the floating circuit 10, and the oil outlet of the main valve assembly is connected to the amplitude changing oil cylinder 26. The switch valve 24 is provided on the oil path between the main valve assembly and the rodless cavity of the amplitude changing oil cylinder 26, the first end of the proportional throttle valve 25 is connected to the oil path between the main valve assembly and the rodless cavity of the amplitude changing oil cylinder 26, and the second end of the proportional throttle valve 25 is connected to the oil path between the main valve assembly and the rod cavity of the amplitude changing oil cylinder 26. In this embodiment, the switch valve 24 is a two-position two-way switch valve 24.

[0046] The main valve assembly of the present invention has two embodiments, such as Figure 1 As shown, in the first embodiment, the main valve assembly includes a pressure compensating valve 29, a variable amplitude multi-way valve 21, a second shuttle valve 23 and a third shuttle valve 22, the oil inlet of the pressure compensating valve 29 is connected to the oil outlet of the electro-hydraulic proportional pump 2, the control oil port of the pressure compensating valve 29 is connected to the first shuttle valve 12 in the floating circuit 10 through the second shuttle valve 23, the oil outlet of the pressure compensating valve 29 is connected to the first port of the variable amplitude multi-way valve 21, and the second and third ports of the variable amplitude multi-way valve 21 serve as the oil outlet of the main valve assembly; the two ends of the third shuttle valve 22 are respectively connected to the second port of the variable amplitude multi-way valve 21, and the third shuttle valve 22 is also connected to the second shuttle valve 23.

[0047] When performing the up action of the boom, the output flow of the electro-hydraulic proportional pump 2 flows into the rodless chamber of the boom cylinder 26 through the pressure compensation valve 29, the boom multi-way valve 21 and the switch valve 24; when performing the down action of the boom, the oil in the rodless chamber of the boom cylinder 26 enters the rod chamber of the boom cylinder 26 through the switch valve 24 and the proportional throttle valve 25 under the action of the boom's own load.

[0048] The main valve components of the telescopic circuit 30, the turntable circuit 40, the leveling circuit 50 and the steering circuit 80 are similar to the main valve components of the luffing circuit 20, and also include a pressure compensation valve 29, a luffing multi-way valve 21, a second shuttle valve 23 and a third shuttle valve 22. The first shuttle valve 12 in the floating circuit 10 is connected to the second shuttle valve in the luffing circuit 20, the second shuttle valve in the luffing circuit 20 is connected to the second shuttle valve in the telescopic circuit 30, the second shuttle valve in the telescopic circuit 30 is connected to the second shuttle valve in the turntable circuit 40, the second shuttle valve in the turntable circuit 40 is connected to the second shuttle valve in the leveling circuit 50, and the second shuttle valve in the leveling circuit 50 is connected to the second shuttle valve in the steering circuit 80. When the boom moves, the first shuttle valve 12, the second shuttle valve 23 and the third shuttle valve 22 select the maximum pressure at the outlet of each multi-way valve in the boom movement, and apply the maximum pressure to the control oil port of the first reversing valve 11. The first reversing valve 11 works in the left position to close this oil circuit to prevent the outlet pressure of the electro-hydraulic proportional pump 2 from being released through the first reversing valve 11.

[0049] like Figure 2 As shown, in the second embodiment, the main valve assembly includes a cartridge valve 27 and a third reversing valve 28, the oil inlet of the cartridge valve 27 is connected to the oil outlet of the electro-hydraulic proportional pump 2, the oil outlet of the cartridge valve 27 is connected to the first port of the third reversing valve 28, the second port and the third port of the third reversing valve 28 serve as the oil outlet of the main valve assembly; the fourth port of the third reversing valve 28 is connected to the hydraulic oil tank. In this embodiment, the third reversing valve 28 is a three-position four-way reversing valve.

[0050] When performing the up action of the boom, the output flow of the electro-hydraulic proportional pump 2 flows into the rodless chamber of the boom cylinder 26 through the pressure cartridge valve 27, the third reversing valve 28 and the switch valve 24; when performing the down action of the boom, the oil in the rodless chamber of the boom cylinder 26 enters the rod chamber of the boom cylinder 26 through the switch valve 24 and the proportional throttle valve 25 under the action of the boom's own load.

[0051] The main valve components of the telescopic circuit 30, the turntable circuit 40, the leveling circuit 50 and the steering circuit 80 are similar to the main valve components of the luffing circuit 20, and also include a cartridge valve 27 and a third reversing valve 28. The first shuttle valve 12 in the floating circuit 10 is connected to the oil outlets of the cartridge valves in the luffing circuit 20, the telescopic circuit 30, the turntable circuit 40, the leveling circuit 50 and the steering circuit 80. When the boom is in motion, the first shuttle valve 12 feeds back the outlet pressure of the cartridge valve 27 to the control oil port of the first reversing valve 11, and the first reversing valve 11 works in the left position, closing this oil circuit to prevent the outlet pressure of the electro-hydraulic proportional pump 2 from being released through the first reversing valve 11.

[0052] Embodiment 2

[0053] The hydraulic control method provided by the embodiment of the present invention and applied to the hydraulic control system in the first embodiment of the present application comprises the following steps:

[0054] Step 1: Control the outlet flow of the electro-hydraulic proportional pump according to the desired flow.

[0055] Its previous flow rate is determined according to the electrical signal output by the operating handle. The flow rate corresponding to the electrical signal output by the operating handle is the expected flow rate, that is, the control unit controls the outlet flow rate of the electro-hydraulic proportional pump according to the electrical signal output by the operating handle.

[0056] Step 2: Obtain the real-time torque of the speed regulating motor, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump.

[0057] When the outlet flow of the electro-hydraulic proportional pump is controlled according to the desired flow, the real-time torque of the speed regulating motor can be collected by using the speed torque sensor, and the real-time outlet pressure and real-time outlet flow of the electro-hydraulic proportional pump can be collected by using the pressure sensor and the flow sensor, respectively, and these sensor data are fed back to the control unit.

[0058] Step 3: Determine the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump.

[0059] The control unit determines the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump. The real-time total efficiency of the power unit is equal to the product of the real-time efficiency of the speed regulating motor and the real-time efficiency of the electro-hydraulic proportional pump. The real-time efficiency of the electro-hydraulic proportional pump can be determined according to the real-time outlet pressure and the real-time outlet flow, and the real-time efficiency of the speed regulating motor can be determined according to the real-time torque, and then the real-time total efficiency of the power unit can be obtained.

[0060] The efficiency calculation of speed regulating motors and electro-hydraulic proportional pumps is a prior art.

[0061] Step 4: Control the speed of the speed regulating motor and the displacement of the electro-hydraulic proportional pump in real time with the goal of maximizing the real-time overall efficiency of the power unit.

[0062] What is disclosed above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, which should be covered within the protection scope of the present invention.

Claims

1. A hydraulic control system, comprising a control unit, a power unit and various functional circuits; characterized in that: The power unit includes a speed regulating motor and an electro-hydraulic proportional pump driven by the speed regulating motor; the functional circuit includes a floating circuit, a luffing circuit, a telescopic circuit, a turntable circuit, a leveling circuit and a steering circuit; the oil outlet of the electro-hydraulic proportional pump is connected to the main valve components in the floating circuit, the luffing circuit, the telescopic circuit, the turntable circuit, the leveling circuit and the steering circuit; The control unit is used to control the outlet flow of the electro-hydraulic proportional pump according to the expected flow; determine the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump; and control the speed of the speed regulating motor and the displacement of the electro-hydraulic proportional pump in real time with the goal of maximizing the real-time total efficiency of the power unit.

2. The hydraulic control system according to claim 1, characterized in that: The floating circuit includes a first reversing valve, a first shuttle valve, a pressure reducing valve, a second reversing valve, a floating multi-way valve, a two-way balancing valve and a floating oil cylinder; the oil inlet of the first reversing valve and the oil inlet of the pressure reducing valve are respectively connected to the oil outlet of the electro-hydraulic proportional pump, the oil outlet of the first reversing valve and the oil drain port of the pressure reducing valve are respectively connected to the hydraulic oil tank, the control oil port of the first reversing valve is connected to the oil outlet of the pressure reducing valve and the oil inlet of the second reversing valve through the first shuttle valve, the first shuttle valve is also connected to the amplitude variation circuit, the telescopic circuit, the turntable circuit, the leveling circuit and the steering circuit; the oil outlet of the second reversing valve is connected to the two-way balancing valve through the floating multi-way valve, and the two-way balancing valve is connected to the floating oil cylinder.

3. The hydraulic control system according to claim 2, characterized in that: A throttling device is also provided in the oil circuit between the pressure reducing valve and the second reversing valve, and the throttling device is a fixed throttling hole or a variable throttling hole.

4. The hydraulic control system according to claim 1, characterized in that: A filter is also provided at the oil outlet of the electro-hydraulic proportional pump.

5. The hydraulic control system according to claim 1, characterized in that: A one-way valve is also provided at the oil inlet of the amplitude variation circuit.

6. The hydraulic control system according to any one of claims 1 to 5, characterized in that: The amplitude variation circuit includes a main valve assembly, a switching valve, a proportional throttle valve and an amplitude variation cylinder, the oil inlet of the main valve assembly is connected to the oil outlet of the electro-hydraulic proportional pump, the control oil port of the main valve assembly is connected to the first shuttle valve in the floating circuit, and the oil outlet of the main valve assembly is connected to the amplitude variation cylinder; a switching valve is provided on the oil circuit between the main valve assembly and the rodless chamber of the amplitude variation cylinder, the first end of the proportional throttle valve is connected to the oil circuit between the main valve assembly and the rodless chamber of the amplitude variation cylinder, and the second end of the proportional throttle valve is connected to the oil circuit between the main valve assembly and the rod chamber of the amplitude variation cylinder.

7. The hydraulic control system according to claim 6, characterized in that: The main valve assembly includes a pressure compensating valve, a variable amplitude multi-way valve, a second shuttle valve and a third shuttle valve. The oil inlet of the pressure compensating valve is connected to the oil outlet of the electro-hydraulic proportional pump, the control oil port of the pressure compensating valve is connected to the first shuttle valve in the floating circuit through the second shuttle valve, the oil outlet of the pressure compensating valve is connected to the first port of the variable amplitude multi-way valve, the second port and the third port of the variable amplitude multi-way valve serve as the oil outlet of the main valve assembly; the two ends of the third shuttle valve are respectively connected to the second port of the variable amplitude multi-way valve, and the third shuttle valve is also connected to the second shuttle valve.

8. The hydraulic control system according to claim 6, characterized in that: The main valve assembly includes a cartridge valve and a third reversing valve, the oil inlet of the cartridge valve is connected to the oil outlet of the electro-hydraulic proportional pump, the oil outlet of the cartridge valve is connected to the first port of the third reversing valve, the second port and the third port of the third reversing valve serve as the oil outlet of the main valve assembly; the fourth port of the third reversing valve is connected to the hydraulic oil tank; the first shuttle valve in the floating circuit is connected to the oil outlet of the cartridge valve, the telescopic circuit, the turntable circuit, the leveling circuit and the steering circuit.

9. A hydraulic control method, characterized in that: Applied to the hydraulic control system according to any one of claims 1 to 8, the control method comprises: Control the outlet flow of the electro-hydraulic proportional pump according to the desired flow; Obtain the real-time torque of the speed regulating motor, the real-time outlet pressure and real-time outlet flow of the electro-hydraulic proportional pump; Determine the real-time total efficiency of the power unit according to the real-time torque of the speed regulating motor, the real-time outlet pressure and the real-time outlet flow of the electro-hydraulic proportional pump; The speed of the speed regulating motor and the displacement of the electro-hydraulic proportional pump are controlled in real time with the goal of maximizing the real-time overall efficiency of the power unit.

10. An aerial work platform, characterized in that: The working platform comprises a hydraulic control system as claimed in any one of claims 1 to 8.

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