A load sensing system based on a quantitative pump

Abstract

The utility model provides a kind of load sensitive system based on quantitative pump, including quantitative pump, motor, controller, multiway valve, proportional pilot control module, proportional reversing valve, and multiway valve is load sensitive multiway valve.System controls multiway valve P mouth pressure through back pressure oil circuit and pressure regulating mechanism, and proportional reversing valve or open center multiway valve itself can be selected as regulating mechanism.At the same time, system integrates flow regulating mechanism, and adjusts motor speed to control quantitative pump output flow by detecting the pressure difference of multiway valve P mouth and load sensitive oil circuit.In addition, when pressure difference is over limit, the oil is discharged by using equal difference overflow valve, and the flow is jointly regulated by motor speed control.The system makes the power consumption of pressure source composed of motor+quantitative pump low in standby state, and the pressure is established rapidly in working state, improves system response speed and operating stability.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic control, and in particular to a load-sensitive system based on a fixed displacement pump. Background Technology

[0002] Currently, electric-powered construction machinery is developing rapidly, posing a strong challenge to traditional fuel-powered machinery, and the market share of electric construction machinery continues to rise. In the field of electric-powered construction machinery, its hydraulic control system has also undergone significant changes. For example, the power source of the hydraulic system has been changed to an electric motor driving the hydraulic pump. The speed of the electric motor can be adjusted in real time according to actual operational needs; that is, by changing the speed of the electric motor, precise control of the hydraulic pump's output oil quantity can be achieved.

[0003] In contrast, traditional hydraulic equipment driven by gasoline or diesel engines requires the control of throttle and a series of hydraulic signals to achieve adjustable hydraulic pump output. This involves adjusting the displacement of the variable pump to match the output flow rate with actual demand. However, variable pumps are not only expensive but also have a relatively high failure rate.

[0004] Currently, some electric construction machinery on the market also uses variable pumps. Although this configuration can meet the needs of current working conditions, the system controls the flow by simultaneously adjusting the motor speed and the variable pump displacement. However, the existence of two flow adjustment devices is an over-configuration and fails to solve the problem of the high cost of variable pumps.

[0005] Using a combination of a fixed displacement pump and a load-sensitive valve can also cause a series of problems. To improve the response speed of construction machinery, the motor driving the hydraulic pump is usually set to a standby speed, generally maintained at around 800 revolutions per minute, at which point the output flow rate is considerable. However, this output flow cannot be directly returned to the oil, leading to continuous energy loss and consequently increasing the temperature of the hydraulic system.

[0006] When a fixed displacement pump is used in conjunction with an open-center multi-way valve, if there are multiple actuators connected in parallel in the hydraulic system, pressure will increase and flow will decrease. This phenomenon is particularly noticeable when construction machinery performs complex actions, making it difficult to effectively control the flow and posing significant challenges to the operation of the actuators. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention provides a load-sensitive system based on a metering pump.

[0008] The technical solution adopted by this utility model is: a load-sensitive system based on a fixed displacement pump, including a fixed displacement pump and a multi-way valve. The fixed displacement pump is matched with a motor and a controller. The multi-way valve is provided with a load-sensitive oil circuit. The pressure signal of the load-sensitive oil circuit is input to the controller, which includes a back pressure oil circuit. The two sides of the back pressure oil circuit are respectively connected to the P port of the multi-way valve and the oil tank. A pressure regulating mechanism is provided on the back pressure oil circuit to control the pressure of the P port of the multi-way valve.

[0009] Furthermore, the pressure regulating mechanism is a proportional directional valve.

[0010] Furthermore, the back pressure oil circuit passes through the multi-way valve, which is an open-center multi-way valve. The multi-way valve itself acts as a pressure regulating mechanism: when the main valve core of the multi-way valve is far from the neutral position, it reduces the opening of the back pressure oil circuit at the main valve core, thereby increasing the pressure at the P port of the multi-way valve.

[0011] Furthermore, it also includes a flow regulation mechanism: by detecting the pressure difference between the P port of the multi-way valve and the load-sensitive oil circuit, the motor speed is adjusted, thereby adjusting the output flow of the fixed displacement pump.

[0012] Furthermore, the regulating mechanism includes a controller: when the actuator controlled by the system is in operation, if the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is detected to be greater than the set pressure difference range, the motor speed is reduced; if the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is detected to be less than the set pressure difference range, the motor speed is increased.

[0013] Furthermore, the regulating mechanism also includes a differential pressure relief valve. The inlet of the differential pressure relief valve is connected to the system pressure oil circuit, the pilot ports on both sides are connected to the system pressure oil circuit and the load-sensitive oil circuit respectively, and the outlet is used for oil discharge. When the pressure difference between the P port of the multi-way valve and the load-sensitive oil circuit exceeds the set value of the differential pressure relief valve, the differential pressure relief valve discharges oil. The system flow is regulated by both motor speed control and differential pressure relief valve oil discharge.

[0014] Furthermore, the multi-way valve includes a reversing coupling. The reversing coupling valve body is equipped with a main valve core, which is connected to the P port of the inlet pipeline, the T port of the return pipeline, and the working oil ports A and B. The main valve core is proportionally controlled and is equipped with left, middle, and right positions. Transitional ports P1 and P2 are provided between the P port and the A / B ports. A load-sensitive valve core is provided between the P1 and P2 ports, and the load-sensitive valve core is equipped with left, middle, and right positions. The pilot oil circuits on both sides of the load-sensitive valve core are respectively connected to the P1 port and the system load-sensitive oil circuit. The proportional control of its displacement is achieved by the pressure of the P1 port and the system load-sensitive oil circuit. The oil inlet end of the load-sensitive valve core is connected to the P1 port, and the two oil outlets are respectively connected to the system load-sensitive oil circuit and the P2 port. The oil outlet and oil inlet connected to the system load-sensitive oil circuit are connected through the internal oil passage of the valve core, and the opening between the oil outlet and oil inlet connected to the P2 port is controlled by the displacement of the load-sensitive valve core.

[0015] Furthermore, the multi-way valve includes a reversing coupling. The reversing coupling valve body is equipped with a main valve core, which is connected to the P port of the inlet oil line, the T port of the return oil line, and the working oil ports A and B. The main valve core is proportionally controlled and is equipped with left, middle, and right positions. Transition ports P1 and P2 are provided between the P port and the A / B ports. A load-sensitive valve core is provided between the P1 and P2 ports. The load-sensitive valve core is equipped with left, middle, and right positions. The pilot oil circuits on both sides of the load-sensitive valve core are respectively connected to the P1 port and the system load-sensitive valve core. The oil circuit achieves proportional control of its displacement through the pressure of the system load-sensitive oil circuit via port P1; the oil inlet of the load-sensitive valve core is connected to port P1, and the two oil outlets are respectively connected to the system load-sensitive oil circuit and port P2. The oil outlet and oil inlet connected to the system load-sensitive oil circuit are connected through the oil passage inside the valve core, and the opening between the oil outlet and oil inlet connected to port P2 is controlled by the displacement of the load-sensitive valve core. The main valve core is also equipped with back pressure passages P3 and P4, and the opening of the oil ports from P3 to P4 is controlled by the displacement of the main valve core.

[0016] This invention employs a back-pressure oil circuit in conjunction with an open-center multi-way valve, enabling the pressure source composed of a motor and a fixed-displacement pump to have low power consumption in standby mode and rapid pressure build-up in operating mode, thus allowing the system to quickly transition from standby to operating mode. During system operation, the controller controls the system flow rate in real time based on the pressure difference between the multi-way valve inlet and the load-sensitive oil circuit, and controls the motor speed to control the pump's output flow rate in real time. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the system in Embodiment 1 of this utility model; Figure 2 This is a schematic diagram of the multi-way valve reversing connection in Embodiment 1 of this utility model; Figure 3 This is a schematic diagram of the system in Embodiment 2 of this utility model; Figure 4 This is a schematic diagram of the multi-way valve reversing connection in Embodiment 2 of this utility model.

[0018] In the diagram: 10-displacement pump, 11-motor, 12-controller, 2-multi-way valve, 21-main valve core, 22-load-sensitive valve core, 23-third relief valve, 24-fourth relief valve, 25-first relief valve, 26-second relief valve, 27-load-sensitive constant flow valve, 3-proportional pilot control module, 4-proportional directional valve. Detailed Implementation

[0019] Example 1: like Figure 1As shown, a load-sensitive system based on a metering pump includes a metering pump 10, a motor 11, a controller 12, a multi-way valve 2, a proportional pilot control module 3, and a proportional directional valve 4. The multi-way valve 2 is a load-sensitive multi-way valve, including two sets of directional valve couplings, a first relief valve 25, a second relief valve 26, and a load-sensitive constant flow valve 27. The multi-way valve 2 can be an open-center multi-way valve, a closed-center multi-way valve, or any other type of multi-way valve structure.

[0020] like Figure 2 As shown, the reversing coupling includes a main valve core 21 and a load-sensitive valve core 22 disposed within the valve body. The reversing coupling valve body is provided with a P port, a T port, and working oil ports A and B. The main valve core 21 is proportionally controlled and is provided with left, middle, and right positions. Transitional ports P1 and P2 are provided between ports P and A and B. The load-sensitive valve core is disposed between ports P1 and P2, and is provided with left, middle, and right positions. The pilot oil circuits on both sides of the load-sensitive valve core are respectively connected to port P1 and the system load-sensitive oil circuit. The proportional control of its displacement is achieved by the pressure of port P1 and the system load-sensitive oil circuit. The oil inlet of the load-sensitive valve core is connected to port P1, and the two oil outlets are respectively connected to the system load-sensitive oil circuit and port P2. The oil outlet and oil inlet connected to the system load-sensitive oil circuit are connected through an internal oil passage of the valve core. The opening between the oil outlet and oil inlet connected to port P2 is controlled by the displacement of the load-sensitive valve core.

[0021] Both ends of the main valve core 2 are equipped with hydraulic pilot oil circuits for controlling the valve core reversal. Each hydraulic pilot oil circuit is controlled by the proportional pilot control module 3. The inlet of the proportional directional valve 4 is connected to the oil circuit between the fixed displacement pump 10 and the P port of the multi-way valve reversing linkage, and the outlet is connected to the oil tank. One side of the valve core of the proportional directional valve 4 is a spring, and the other side is equipped with a hydraulic pilot oil circuit, which is controlled by the proportional pilot control module 3. The proportional pilot control module 3 includes several proportional pressure reducing valves. The input end of each proportional pressure reducing valve is connected to the pilot pressure source, and the output end corresponds to each pilot control oil circuit of the multi-way valve reversing linkage and the proportional directional valve, respectively. By adjusting the output pressure through the proportional pressure reducing valves, the displacement of the corresponding valve core is controlled. In this embodiment, the electromagnet of the proportional pressure reducing valve is controlled by the control terminals XD1-XD5 of the controller 12.

[0022] The first relief valve 25 is a differential relief valve. Its inlet is connected to the system pressure oil circuit, its two pilot ports are connected to the system pressure oil circuit and the load-sensitive oil circuit respectively, and its outlet is connected to the return oil line. The load-sensitive oil circuit is marked as LS in the figure. The differential pressure setting value of the first relief valve 25 is higher than the set pressure range of the controller 12. When the differential pressure between the multi-way valve P port and the load-sensitive oil circuit is too large, the system flow can be adjusted by reducing the input flow by decreasing the motor speed and by draining oil. The first relief valve 25 can also relieve instantaneous pressure fluctuations in the system to prevent damage to the components in the system from impact.

[0023] The second overflow valve 26 and the load-sensitive constant flow valve 27 are connected in parallel. The oil inlet of the second overflow valve 26 and the oil port on one side of the load-sensitive constant flow valve 27 are connected to the load-sensitive oil circuit. The oil outlet of the second overflow valve 26 and the oil port on the other side of the load-sensitive constant flow valve 27 are connected to a separate oil circuit to return to the oil tank to avoid interference from the return oil of other components.

[0024] Pressure detection devices are installed in the load-sensitive oil circuit and the P-port oil circuit of the multi-way valve respectively. The pressure data of the load-sensitive oil circuit and the P-port oil circuit of the multi-way valve are transmitted to the controller 12 in real time when the actuator controlled by the system is activated. The controller 12 acts as a flow regulation mechanism, sets the pressure difference range of the load-sensitive oil circuit and the P-port oil circuit of the multi-way valve according to the actual working conditions, and presets the minimum speed of the motor 11.

[0025] When the actuator needs to operate, a control signal is input. In this embodiment, the control signal is generated by pulling the pilot handle. The starter motor 11 initially runs at its lowest speed. The pilot control module 3 drives the corresponding directional valve core of the multi-way valve and the valve core of the proportional directional valve 4 to move. The opening of the proportional directional valve 4 gradually decreases, causing the pressure at the P port of the multi-way valve to increase. At the same time, the oil passage from the P port of the multi-way valve to the working oil ports A / B is about to open. At this time, the system is in the pre-pressure build-up stage, and the pressure in the load-sensitive oil passage has not yet been established, remaining in a low-pressure or zero-pressure state. At this time, the controller 12 does not control the speed of the motor 11. After the oil passage from the P port of the multi-way valve to the working oil ports A / B opens, the load... Once the sensitive oil circuit pressure is established, the controller begins to control the motor 11 speed based on the pressure difference between the multi-way valve P port and the load-sensitive oil circuit: when the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is lower than the set pressure range, it indicates that the pump output flow cannot meet the working flow, so the motor 11 speed is increased to increase the system flow; when the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is higher than the set pressure range, it indicates that the pump output flow is too large, so the motor 11 speed is decreased to reduce the system flow; when the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is within the set pressure range, the motor 11 speed remains unchanged; when the controller 12 controls the motor 11 speed, it must not be lower than the preset minimum speed. In this embodiment, the preset minimum speed of the motor 11 varies depending on the different fixed displacement pumps and different actuators, and in special cases, a minimum speed may not be set. The motor 11 can be in the minimum speed state when the actuator is not moving, and can respond quickly when the system receives an action command, or it can be in a stopped state to further save energy.

[0026] Example 2: Compared to Embodiment 1, this embodiment omits the proportional directional valve 4 and adds a back pressure passage P3-P4 to the main valve core function of the multi-way valve. In this case, the multi-way valve is an open-center multi-way valve. Ports P3-P4 are fully open in the neutral position and fully closed in the left or right position. During the transition from the neutral to the left / right position, the opening of ports P3-P4 gradually decreases as the displacement away from the neutral position increases, thereby achieving a synchronous increase in the opening of port P to working ports A / B and the gradual accumulation of back pressure.

Claims

1. A load sensing system based on a fixed displacement pump, comprising a fixed displacement pump, a multi-way valve, wherein, The metering pump is matched with a motor and a controller. The multi-way valve is provided with a load-sensitive oil circuit. The pressure signal of the load-sensitive oil circuit is input to the controller. The feature is that it includes a back pressure oil circuit. The two sides of the back pressure oil circuit are respectively connected to the P port of the multi-way valve and the oil tank. A pressure regulating mechanism is provided on the back pressure oil circuit to control the pressure of the P port of the multi-way valve.

2. A load sensing system based on a fixed displacement pump according to claim 1, characterized in that: The pressure regulating mechanism is a proportional directional valve.

3. A load sensing system based on a fixed displacement pump according to claim 1, characterized in that: The back pressure oil circuit passes through the multi-way valve, which is an open-center multi-way valve. The multi-way valve itself acts as a pressure regulating mechanism: when the main valve core of the multi-way valve is far from the neutral position, it reduces the opening of the back pressure oil circuit at the main valve core, thereby increasing the pressure at the P port of the multi-way valve.

4. A load sensing system based on a fixed displacement pump according to claim 1, 2 or 3, characterized in that: It also includes a flow regulation mechanism: by detecting the pressure difference between the P port of the multi-way valve and the load-sensitive oil circuit, the motor speed is adjusted, thereby adjusting the output flow of the fixed displacement pump.

5. A load sensing system based on a fixed displacement pump according to claim 4, characterized in that: The regulating mechanism includes a controller: when the actuator controlled by the system is in operation, if the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is detected to be greater than the set pressure difference range, the motor speed is reduced; if the pressure difference between the multi-way valve P port and the load-sensitive oil circuit is detected to be less than the set pressure difference range, the motor speed is increased.

6. A load sensing system based on a fixed displacement pump according to claim 5, characterized in that: The regulating mechanism also includes a differential pressure relief valve. The inlet of the differential pressure relief valve is connected to the system pressure oil circuit, the pilot ports on both sides are connected to the system pressure oil circuit and the load-sensitive oil circuit respectively, and the outlet is used for oil discharge. When the pressure difference between the multi-way valve P port and the load-sensitive oil circuit exceeds the set value of the differential pressure relief valve, the differential pressure relief valve discharges oil. The system flow rate is regulated by both motor speed control and differential pressure relief valve oil discharge.

7. A load-sensing system based on a fixed-displacement pump according to claim 2, characterized in that: The multi-way valve includes a reversing coupling. The reversing coupling valve body is equipped with a main valve core, which is connected to the P port of the inlet pipeline, the T port of the return pipeline, and working ports A and B. The main valve core is proportionally controlled and has left, middle, and right positions. Transition ports P1 and P2 are provided between the P port and the A / B ports. A load-sensitive valve core is provided between the P1 and P2 ports. The load-sensitive valve core has left, middle, and right positions. Pilot oil circuits on both sides of the load-sensitive valve core are respectively connected to the P1 port and the system load-sensitive oil circuit. The proportional control of its displacement is achieved by the pressure of the P1 port and the system load-sensitive oil circuit. The oil inlet end of the load-sensitive valve core is connected to the P1 port, and the two oil outlets are respectively connected to the system load-sensitive oil circuit and the P2 port. The oil outlet and oil inlet connected to the system load-sensitive oil circuit are connected through an internal oil passage in the valve core. The opening between the oil outlet and oil inlet connected to the P2 port is controlled by the displacement of the load-sensitive valve core.

8. A load sensing system based on a fixed displacement pump according to claim 3, characterized in that: The multi-way valve includes a reversing coupling. The reversing coupling valve body is equipped with a main valve core, which is connected to the P port of the inlet oil pipeline, the T port of the return oil pipeline, and working oil ports A and B. The main valve core is proportionally controlled and has left, middle, and right positions. Transition ports P1 and P2 are provided between the P port and the A / B ports. A load-sensitive valve core is provided between the P1 and P2 ports. The load-sensitive valve core has left, middle, and right positions. Pilot oil circuits on both sides of the load-sensitive valve core are respectively connected to the P1 port and the system load-sensitive oil circuit. The displacement of the valve core is proportionally controlled by the pressure of the load-sensitive oil circuit through port P1. The oil inlet of the load-sensitive valve core is connected to port P1, and the two oil outlets are connected to the load-sensitive oil circuit and port P2, respectively. The oil outlet and oil inlet of the load-sensitive oil circuit are connected through the oil passage inside the valve core. The opening between the oil outlet and oil inlet of port P2 is controlled by the displacement of the load-sensitive valve core. The main valve core is also equipped with back pressure passages P3 and P4. The opening of the oil ports from P3 to P4 is controlled by the displacement of the main valve core.

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