A load sensing system and control method based on the pressure regulation of an overflow valve

Abstract

The present invention discloses a load-sensing system based on pressure regulation of an overflow valve and its control method. The system includes a pressure acquisition device, a controller, a control display screen, and a proportional overflow valve. The proportional overflow valve is connected to the power source of the hydraulic system, and the proportional overflow valve, the control display screen, and the pressure acquisition device are all connected to the controller. The control method installs a proportional overflow valve between the oil inlet and the oil return port, and adjusts the opening degree of the proportional overflow valve in real time according to the load size, so as to control the pressure of the oil inlet and the oil return port, achieving the purpose of load sensing. By adopting the above load-sensing system based on pressure regulation of an overflow valve and its control method, the output current of the proportional overflow valve installed between the oil inlet and the oil return port is adjusted through the change of the load pressure, achieving the effect of load sensing, with low cost and flexible adjustment.

Description

Technical Field

[0001] The present invention relates to the technical field of load-sensitive systems, and in particular to a load-sensitive system and a control method based on the pressure regulation of an overflow valve. Background Art

[0002] A load-sensitive system is a hydraulic circuit that senses the pressure-flow requirements of the system and provides only the required flow and pressure. The load-sensitive control system has low power loss and much higher efficiency than conventional hydraulic systems, so its application is becoming more and more widespread. Generally, a load-sensitive system is based on hydraulic components such as hydraulic variable pumps, flow control valves, and pressure control valves, which have disadvantages such as high cost and inflexible control. Therefore, there is an urgent need for a load-sensitive control system and method with a simple structure, convenient control, and low cost. In a hydraulic system without load sensitivity, the power loss is high, the efficiency is low, and the system stability is poor. The traditional load-sensitive system is based on hydraulic components such as hydraulic variable pumps, flow control valves, and pressure control valves, with high costs. The parameter determination and adjustment of the load-sensitive system based on traditional hydraulic components such as hydraulic variable pumps, flow control valves, and pressure control valves are not flexible. Summary of the Invention

[0003] The object of the present invention is to provide a load-sensitive system and a control method based on the pressure regulation of an overflow valve. By changing the load pressure, the output current of the proportional overflow valve installed between the inlet port and the return port is adjusted to achieve the effect of load sensitivity, with low cost and flexible adjustment.

[0004] To achieve the above object, the present invention provides a load-sensitive system based on the pressure regulation of an overflow valve, including a pressure acquisition device, a controller, a control display screen, and a proportional overflow valve. The proportional overflow valve is connected to the power source of the hydraulic system, and the proportional overflow valve, the control display screen, and the pressure acquisition device are all connected to the controller.

[0005] Preferably, the pressure acquisition device includes a first oil port pressure acquisition sensor, a second oil port pressure acquisition sensor, and a system pressure acquisition sensor. The first oil port pressure acquisition sensor and the second oil port pressure acquisition sensor are respectively arranged at the first oil port and the second oil port of the hydraulic motor, and the system pressure acquisition sensor is arranged on the oil outlet pipe of the power source of the hydraulic system.

[0006] Preferably, the first oil port pressure acquisition sensor and the second oil port pressure acquisition sensor are connected to the controller through a filtering module.

[0007] Preferably, the proportional overflow valve is provided with a current detection module, and the current detection module is connected to the controller.

[0008] A control method for a load-sensitive system based on the above-mentioned overflow valve pressure regulation is as follows:

[0009] Step S1: Input set parameters through the control display screen, and calculate the initial current value and the increment coefficient according to the set parameters;

[0010] Step S2: Collect pressure parameters through the pressure acquisition device, and calculate the control output current value according to the collected pressure parameters, the initial current value and the set parameters;

[0011] Step S3: In the increment stage, make the system pressure reach the initial pressure through multiple increments according to the control output current value;

[0012] Step S4: In the steady stage, collect the pressures of the first oil port and the second oil port of the hydraulic motor in real time, and calculate the control output current value according to the pressures of the first oil port and the second oil port of the hydraulic motor;

[0013] Step S5: When the control output current value is greater than the maximum protection current value, the control output current value is the maximum protection current value;

[0014] Step S6: The controller controls the output current of the proportional overflow valve according to the control output current value;

[0015] Step S7: When the load is in a changing state, repeat steps S2 - S6. When the load no longer changes, the system pressure reaches stability.

[0016] Preferably, the set parameters include the maximum allowable pressure Pmax of the system, the maximum allowable current Imax of the proportional overflow valve, the threshold current I0, the system-set return oil pressure P0, and the pressure acquisition period Ts.

[0017] Preferably, the calculation formula for the increment coefficient K is as follows:

[0018] K = (Imax - I0) / Pmax;

[0019] The calculation formula for the initial current value I1 is as follows:

[0020] I1 = I0 + K * P0.

[0021] Preferably, the first N sampling periods are the increment stage, and each increment is I1 / N;

[0022] Starting from the (N + 1)-th sampling period is the steady stage. The controller collects the pressure values of the first oil port and the second oil port in each period and calculates their difference, filters the pressure values collected in the previous N times and calculates their average pressure difference ABS(Pa - Pb).

[0023] Preferably, the calculation formula for the control output current value I is:

[0024] I = I0 + K[ABS(Pa - Pb) + P0].

[0025] Preferably, in step S6, when the difference between the controlled output current value I and the current output current is within the magnitude of Ic, the output current is controlled to remain the current value unchanged; when the difference between the controlled output current value I and the current output current is greater than Ic, the controlled output current value I is output.

[0026] Therefore, the present invention adopts the above-mentioned load-sensing system and control method based on the pressure regulation of the overflow valve, and has the following beneficial effects: simple structure, convenient control, easy to install, and can be applied to various control occasions; parameters can be freely set, and the adjustment has great flexibility; by changing the load pressure, the output current of the proportional overflow valve installed between the inlet port and the return port is adjusted to achieve the effect of load sensing.

[0027] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of a load-sensing system based on the pressure regulation of the overflow valve according to the present invention;

[0029] Figure 2 is a flowchart of a control method for a load-sensing system based on the pressure regulation of the overflow valve according to the present invention

[0030] Figure 3 is a relationship diagram between the system pressure and the current of the proportional overflow valve of the present invention.

[0031] Wherein: P is the inlet port, T is the return port, A and B are the working oil ports of the hydraulic motor, OP1 and OP2 are pressure sensors, and DT is the proportional overflow valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Embodiment

[0033] Figure 1 is a schematic structural diagram of a load-sensing system based on the pressure regulation of the overflow valve according to the present invention. As shown in the figure, a load-sensing system based on the pressure regulation of the overflow valve includes a pressure acquisition device, a controller, a control display screen, and a proportional overflow valve. The proportional overflow valve is connected to the power source of the hydraulic system, and the proportional overflow valve, the control display screen, and the pressure acquisition device are all connected to the controller.

[0034] The pressure acquisition device includes a first oil port pressure acquisition sensor, a second oil port pressure acquisition sensor, and a system pressure acquisition sensor. The first oil port pressure acquisition sensor and the second oil port pressure acquisition sensor are respectively arranged at the first oil port (A) and the second oil port (B) of the hydraulic motor to collect the pressure of the working oil ports of the hydraulic motor. When the flow rate of the hydraulic system is constant, the relationship between the system pressure P and the proportional overflow valve current I can be approximately as Figure 3 shown in the linear relationship. When the load pressure changes, the pressure difference between the first oil port (A) and the second oil port (B) changes accordingly. When the load pressure is greater, the pressure difference between the first oil port (A) and the second oil port (B) is greater; conversely, when the load pressure is smaller, the pressure difference between the first oil port (A) and the second oil port (B) is smaller. The pressure difference between the first oil port (A) and the second oil port (B) reflects the magnitude of the load pressure in real time. The first oil port pressure acquisition sensor and the second oil port pressure acquisition sensor are connected to the controller through a filtering module to improve the accuracy of the acquired data. The system pressure acquisition sensor is arranged on the outlet oil pipe of the power source of the hydraulic system to collect the system pressure. The proportional overflow valve is provided with a current detection module for detecting the actual current of the proportional overflow valve, and the current detection module is connected to the controller.

[0035] Figure 2 This is the control method flow chart of a load-sensitive system based on overflow valve pressure regulation according to the present invention. As shown in the figure, a control method of a load-sensitive system based on the above-mentioned overflow valve pressure regulation specifically includes the following steps:

[0036] Step S1: Input set parameters through the control display screen, and calculate the initial current value and the increment coefficient according to the set parameters. The set parameters include the maximum allowable system pressure Pmax, the maximum allowable current Imax of the proportional overflow valve, the threshold current I0, the system-set return oil pressure P0, and the pressure acquisition period Ts. The parameters can be freely set, and the adjustment has great flexibility.

[0037] The calculation formula of the increment coefficient K is as follows:

[0038] K = (Imax - I0) / Pmax.

[0039] The calculation formula of the initial current value I1 is as follows:

[0040] I1 = I0 + K * P0.

[0041] Step S2: Collect pressure parameters through the pressure acquisition device, and calculate the control output current value according to the acquired pressure parameters, the initial current value, and the set parameters.

[0042] Step S3: In the increasing stage, the first N sampling periods are the increasing stage. According to the control output current value, the system pressure reaches the initial pressure after multiple increments, and each increment is I1 / N.

[0043] Step S4: In the steady stage, starting from the (N + 1)-th sampling period as the steady stage, the pressures at the first oil port and the second oil port of the hydraulic motor are collected in real time. The control output current value is calculated based on the pressures at the first oil port and the second oil port of the hydraulic motor. The controller collects the pressure values at the first oil port and the second oil port in each period and calculates their difference, filters the pressure values collected in the previous N times and calculates their average pressure difference ABS(Pa - Pb). The calculation formula for the control output current value I is:

[0044] I = I0 + K[ABS(Pa - Pb) + P0].

[0045] Step S5: When the control output current value is greater than the maximum protection current value, the control output current value is set to the maximum protection current value.

[0046] Step S6: The controller controls the output current of the proportional relief valve according to the control output current value. When the difference between the control output current value I and the current output current is within the magnitude of Ic, the control output current remains the current value unchanged. When the difference between the control output current value I and the current output current is greater than Ic, the control output current value I is output to prevent repeated adjustment within a small range and make the system reach stability as soon as possible.

[0047] Step S7: When the load is in a changing state, repeat Steps S2 - S6. When the load no longer changes, the system pressure reaches stability. The adjustment of the system pressure will cause changes in the pressures at the first oil port (A) and the second oil port (B), but when the load is stable, the final load pressure remains constant. After multiple adjustments, the system pressure is kept stable, and the pressure at the oil return port always remains within a certain range, achieving the purpose of load sensing.

[0048] Therefore, the present invention adopts the above load sensing system and control method based on relief valve pressure regulation, which has a simple structure and convenient control. By changing the load pressure, the output current of the proportional relief valve installed between the oil inlet and the oil return port is adjusted to achieve the effect of load sensing.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A control method for a load - sensitive system based on pressure regulation of an overflow valve, characterized in that, The load - sensitive system based on pressure regulation of an overflow valve includes a pressure acquisition device, a controller, a control display screen, and a proportional overflow valve. The proportional overflow valve is connected to the power source of the hydraulic system. The proportional overflow valve, the control display screen, and the pressure acquisition device are all connected to the controller; The pressure acquisition device includes a first - port pressure acquisition sensor, a second - port pressure acquisition sensor, and a system - pressure acquisition sensor. The first - port pressure acquisition sensor and the second - port pressure acquisition sensor are respectively arranged at the first port and the second port of the hydraulic motor, and the system - pressure acquisition sensor is arranged on the outlet pipe of the power source of the hydraulic system; The proportional overflow valve is provided with a current detection module, and the current detection module is connected to the controller; the first - port pressure acquisition sensor and the second - port pressure acquisition sensor are connected to the controller through a filtering module; The specific steps of the control method are as follows: Step S1: Input set parameters through the control display screen, and calculate the initial current value and the increment coefficient according to the set parameters; Step S2: Collect pressure parameters through the pressure acquisition device, and calculate the control output current value according to the collected pressure parameters, the initial current value, and the set parameters; Step S3: In the increasing stage, make the system pressure reach the initial pressure through multiple increments according to the control output current value; Step S4: In the stable stage, collect the pressures of the first port and the second port of the hydraulic motor in real - time, and calculate the control output current value according to the pressures of the first port and the second port of the hydraulic motor; Step S5: When the control output current value is greater than the maximum protection current value, the control output current value is the maximum protection current value; Step S6: The controller controls the output current of the proportional overflow valve according to the control output current value; Step S7: When the load is in a changing state, repeat steps S2 - S6. When the load no longer changes, the system pressure reaches stability.

2. The control method of a load-sensitive system based on the pressure regulation of an overflow valve according to claim 1, characterized in that: The set parameters include the maximum allowable system pressure Pmax, the maximum allowable current Imax of the proportional overflow valve, the threshold current I0, the system - set return - oil pressure P0, and the pressure acquisition period Ts.

3. A control method for a load - sensitive system based on pressure regulation of an overflow valve according to claim 2, characterized in that, The calculation formula for the increment coefficient K is as follows: K = (Imax - I0) / Pmax; The calculation formula for the initial current value I1 is as follows: 。 4. A control method for a load - sensitive system based on pressure regulation of an overflow valve according to claim 3, characterized in that: The first N sampling periods are the increasing stage, and each increment is I1 / N; Starting from the (N + 1) - th sampling period is the stable stage. The controller collects the pressure values of the first port and the second port within each period and calculates their difference, filters the pressure values collected in the previous N times, and calculates the average pressure difference ABS(Pa - Pb).

5. The control method of a load sensing system based on overflow valve pressure regulation according to claim 4, characterized in that, The calculation formula for the control output current value I is: I = I0+K[ABS(Pa - Pb)+P0].

6. The control method of a load-sensitive system based on overflow valve pressure regulation according to claim 5, characterized in that: In step S6, when the difference between the controlled output current value I and the current output current is within the magnitude of Ic, the controlled output current is maintained at the current value. When the difference between the controlled output current value I and the current output current is greater than Ic, the controlled output current value I is output.

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