阅读说明：本技术 一种电负载敏感系统及其控制方法 (Electric load sensing system and control method thereof ) 是由 张楠 王晓飞 陈思瑶 靳翠军 于 2021-10-19 设计创作，主要内容包括：本发明公开一种电负载敏感系统及其控制方法,主臂变幅比例阀Y2是三位七通比例阀,中位是“Y”型机能,主臂变幅比例阀Y2的3油口、6油口和7油口中位时相连通,主臂变幅比例阀Y2的1油口连通主阀P口,主臂变幅比例阀Y2的3油口连通泄油T口,主臂变幅比例阀Y2的6油口通过主阀A1油口连通平衡阀V1油口,7油口通过主阀B1油口连通平衡阀V2油口；泄油T口连通油箱,压力传感器YP1的压力敏感元件安装在主阀P口上,压力传感器YP2的压力敏感元件安装在负载LS口。本发明利用PID控制算法,调节电控泵比例阀的输出电流值,使主阀P口与负载压力口之间的压差可控。(The invention discloses an electric load sensing system and a control method thereof.A main arm variable amplitude proportional valve Y2 is a three-position seven-way proportional valve, the middle position is a Y-shaped function, A3 oil port and a 6 oil port of a main arm variable amplitude proportional valve Y2 are communicated with the middle position of a 7 oil port, a1 oil port of a main arm variable amplitude proportional valve Y2 is communicated with a main valve P port, A3 oil port of a main arm variable amplitude proportional valve Y2 is communicated with an oil drainage T port, a 6 oil port of a main arm variable amplitude proportional valve Y2 is communicated with a balance valve V1 oil port through a main valve A1 oil port, and a 7 oil port is communicated with a balance valve V2 oil port through a main valve B1 oil port; the oil drainage T port is communicated with an oil tank, a pressure sensing element of a pressure sensor YP1 is arranged on a main valve P port, and a pressure sensing element of a pressure sensor YP2 is arranged on a load LS port. The invention utilizes PID control algorithm to adjust the output current value of the proportional valve of the electric control pump, so that the pressure difference between the main valve P port and the load pressure port is controllable.)

1. An electric load sensing system is characterized by comprising a pressure sensor YP1, a pressure sensor YP2, a controller and a main arm amplitude-changing proportional valve Y2, wherein the main arm amplitude-changing proportional valve Y2 comprises a main arm lower amplitude-changing coil Y2a and a main arm upper amplitude-changing coil Y2b,

the main arm variable amplitude proportional valve Y2 is a three-position seven-way proportional valve, the middle position is a Y-shaped function, A3 oil port, a 6 oil port and a 7 oil port of the main arm variable amplitude proportional valve Y2 are communicated with each other at the middle position, a1 oil port of the main arm variable amplitude proportional valve Y2 is communicated with a main valve P port, A3 oil port of the main arm variable amplitude proportional valve Y2 is communicated with an oil drainage T port, a 6 oil port of the main arm variable amplitude proportional valve Y2 is communicated with a main valve A1 oil port, a 7 oil port is communicated with a main valve B1 oil port, an oil port of the main valve A1 is communicated with an oil port of a balance valve V1, and an oil port of the main valve B1 is communicated with an oil port of the balance valve V2;

the oil drainage T port is communicated with an oil tank, a pressure sensing element of a pressure sensor YP1 is arranged on a main valve P port, and a pressure sensing element of a pressure sensor YP2 is arranged on a load LS port; the pressure sensor YP1, the pressure sensor YP2, the lower amplitude coil Y2a of the control main arm and the upper amplitude coil Y2b of the control main arm are all electrically connected with the controller.

2. The electrical load sensing system according to claim 1, comprising an electrically controlled pump, a plurality of damping holes, a single piston rod cylinder, a two-position three-way valve and an electrically controlled pump proportional valve Y1, wherein an oil pumping port of the electrically controlled pump is communicated with an oil tank, an oil pumping port of the electrically controlled pump is communicated with a main valve P port, and a piston rod of the single piston rod cylinder is fixedly or rotatably connected with a swash plate of the electrically controlled pump;

an oil port 1 of the electric control pump proportional valve Y1 is communicated with an oil port 1 of the two-position three-way valve through a damping hole, and the oil port 1 of the two-position three-way valve is communicated with an oil port of the electric control pump; an oil port 1 of the electric control pump proportional valve Y1 is communicated with an oil port 2 of the two-position three-way valve; the 3 oil ports of the two-position three-way valve are communicated with the rodless cavity of the single-piston rod cylinder through the damping hole, and are communicated with the oil discharging port through the damping hole.

3. The electrical load sensing system as recited in claim 1, comprising a three-position three-way valve and a one-way valve, wherein an oil port 1 of the three-position three-way valve is communicated with a load LS port, an oil port 2 of the three-position three-way valve is communicated with an oil port 2 of the main arm variable amplitude proportional valve Y2 through the one-way valve, and an oil port 3 of the three-position three-way valve is communicated with an oil port 4 of the main arm variable amplitude proportional valve Y2 and an oil port 5 of the main arm variable amplitude proportional valve Y2.

4. An electrical load sensing system according to claim 1, including a relief valve through which the main valve port P communicates with the drain port T.

5. A method for controlling an electrical load sensing system,

with the electrical load sensing system of claims 1-4, performing the method:

the flow pressure characteristic of the main valve is:

ΔP＝P_P-P_L(2)，

wherein Q is the flow through the main arm variable amplitude proportional valve Y2, C_dIs the flow coefficient, A is the flow area of the main arm variable amplitude proportional valve Y2, Δ P is the difference between the pressure at the main valve P port and the load feedback pressure, ρ is the liquid density, P is the flow area of the main arm variable amplitude proportional valve_PIs the pressure value of the main valve P port, P_LIs the load LS port feedback pressure value;

coefficient of flow C_dAnd the liquid density rho is a fixed value, setting delta P, and proportionally increasing or decreasing the flow along with the flow area A of the main arm variable amplitude proportional valve Y2;

the deviation e (t) is: e (t) ═ P_P(t)-P_L(t))-ΔP_s，

Wherein the pressure P of the main valve port P_P(t) and load feedback LS port pressure P_L(t)，ΔP_sIs a set system pressure differential;

when the electric control pump proportional valve Y1 current is increased, the main valve P port pressure P_P(t) is increased; when the electric control pump proportional valve Y1 current value is reduced, the main valve P port pressure P_P(t) decrease;

the basis functions for PID control of the electrical load sensing system are as follows:

wherein the proportionality coefficient K_pIntegral coefficient K_IAnd a differential coefficient K_DFor a set value, the controller periodically collects P according to a PID algorithm_P(t) and P_L(t) periodically calculating the deviation e (t);

setting delta P, periodically adjusting the current value of the proportional valve Y1 of the electric control pump, and further adjusting the pressure P of the main valve P port_P(t) where e (t) is 0.

6. The method as claimed in claim 5, wherein the electrically controlled pump proportional valve Y1 is an electrically proportional pressure control valve.

Technical Field

The invention relates to an electric load sensing system and a control method thereof, belonging to the technical field of aerial work platform control.

Background

The aerial work platform is special equipment for carrying workers and construction equipment to a designated position for control and formulation and carrying out maintenance, installation and other work. With the rapid development of the industries such as shipbuilding, fire fighting, port construction, petrochemical engineering, municipal construction and the like in China, the demand on the aerial work platform is more and more.

The load sensing system is a hydraulic system capable of sensing the size of a load. The hydraulic load sensing system controls the load in a hydraulic control mode according to the sensed load. The electric load sensing system controls the load in an electric control mode according to the sensed size of the load.

At present, due to simple control, hydraulic control load sensitive systems or common hydraulic systems are more commonly used in high-altitude operation platform factories. The existing high-altitude operation platform is mostly provided with a hydraulic control load sensitive system, load pressure is fed back to a variable pump through a long pipeline, and valve banks such as a rotary table action control valve, a platform action control valve and the like need to feed back load pressure signals to the variable pump at the same time. After the proportional valve opening corresponding to the action is opened, the variable pump adjusts the inclination angle of the swash plate according to the pressure feedback signal, controls the required flow output and executes the corresponding action.

The hydraulic control load sensitive system has the following defects: (1) the adjustable range is narrow, and the micromotion performance is poor: the existing high-altitude operation platform is used for a hydraulic control load sensitive system, and the speed can be regulated only by adjusting an opening of a proportional valve due to fixed differential pressure, so that the adjustable range is narrow; the opening of the proportional valve is adjusted to the minimum speed capable of realizing the action, and the micro-mobility is poor compared with an electric control load sensitive system. (2) The pump outlet pressure difference and the load pressure difference are fixed: the existing high-altitude operation platform adopts a hydraulic control load sensitive system, the pressure difference between an outlet of the pump and a load is determined by a load feedback spring in the hydraulic control pump, and the pressure difference of the system can not be adjusted at will after selection. (3) The action speed is greatly influenced by the temperature: the existing high-altitude operation platform is used for a hydraulic control load sensitive system, the system pressure difference mainly comprises the pipeline pressure difference between an outlet of a pump and a port P of a main valve and the front-back pressure difference of the main valve between the port P of the main valve and a load, the temperature is reduced, the viscosity of hydraulic oil is increased, the pipeline pressure difference is increased, the front-back pressure difference of the main valve is reduced, and the action speed is influenced.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the prior art and provide an electric load sensing system and a control method thereof.

In order to achieve the purpose, the invention provides an electric load sensing system which comprises a pressure sensor YP1, a pressure sensor YP2, a controller and a main arm amplitude-changing proportional valve Y2, wherein the main arm amplitude-changing proportional valve Y2 comprises a main arm lower amplitude-changing coil Y2a and a main arm upper amplitude-changing coil Y2b,

the main arm variable amplitude proportional valve Y2 is a three-position seven-way proportional valve, the middle position is a Y-shaped function, A3 oil port, a 6 oil port and a 7 oil port of the main arm variable amplitude proportional valve Y2 are communicated with each other at the middle position, a1 oil port of the main arm variable amplitude proportional valve Y2 is communicated with a main valve P port, A3 oil port of the main arm variable amplitude proportional valve Y2 is communicated with an oil drainage T port, a 6 oil port of the main arm variable amplitude proportional valve Y2 is communicated with a main valve A1 oil port, a 7 oil port is communicated with a main valve B1 oil port, an oil port of the main valve A1 is communicated with an oil port of a balance valve V1, and an oil port of the main valve B1 is communicated with an oil port of the balance valve V2;

the oil drainage T port is communicated with an oil tank, a pressure sensing element of a pressure sensor YP1 is arranged on a main valve P port, and a pressure sensing element of a pressure sensor YP2 is arranged on a load LS port; the pressure sensor YP1, the pressure sensor YP2, the lower amplitude coil Y2a of the control main arm and the upper amplitude coil Y2b of the control main arm are all electrically connected with the controller.

Preferably, the hydraulic control system comprises an electric control pump, a plurality of damping holes, a single piston rod cylinder, a two-position three-way valve and an electric control pump proportional valve Y1, wherein an oil pumping opening of the electric control pump is communicated with an oil tank, an oil pumping opening of the electric control pump is communicated with a main valve P opening, and a piston rod of the single piston rod cylinder is fixedly or rotatably connected with a swash plate of the electric control pump;

an oil port 1 of the electric control pump proportional valve Y1 is communicated with an oil port 1 of the two-position three-way valve through a damping hole, and the oil port 1 of the two-position three-way valve is communicated with an oil port of the electric control pump; an oil port 1 of the electric control pump proportional valve Y1 is communicated with an oil port 2 of the two-position three-way valve; the 3 oil ports of the two-position three-way valve are communicated with the rodless cavity of the single-piston rod cylinder through the damping hole, and are communicated with the oil discharging port through the damping hole.

Preferentially, the three-position three-way valve comprises a three-position three-way valve and a one-way valve, wherein an oil port 1 of the three-position three-way valve is communicated with a load LS port, an oil port 2 of the three-position three-way valve is communicated with an oil port 2 of the main arm variable amplitude proportional valve Y2 through the one-way valve, and an oil port 3 of the three-position three-way valve is communicated with an oil port 4 of the main arm variable amplitude proportional valve Y2 and an oil port 5 of the main arm variable amplitude proportional valve Y2.

Preferably, a relief valve is included through which the main valve port P communicates with the drain port T.

A control method of an electric load sensing system adopts the electric load sensing system and executes the method:

the flow pressure characteristic of the main valve is:

ΔP＝P_P-P_L (2)，

wherein Q is the flow through the main arm variable amplitude proportional valve Y2, C_dIs the flow coefficient, A is the flow area of the main arm variable amplitude proportional valve Y2, Δ P is the difference between the pressure at the main valve P port and the load feedback pressure, ρ is the liquid density, P is the flow area of the main arm variable amplitude proportional valve_PIs the pressure value of the main valve P port, P_LIs the load LS port feedback pressure value;

coefficient of flow C_dAnd the liquid density rho is a fixed value, setting delta P, and proportionally increasing or decreasing the flow along with the flow area A of the main arm variable amplitude proportional valve Y2;

the deviation e (t) is: e (t) ═ P_P(t)-P_L(t))-ΔP_s，

Wherein the pressure P of the main valve port P_P(t) and load feedback LS port pressure P_L(t)，ΔP_sIs a set system pressure differential;

when the electric control pump proportional valve Y1 current is increased, the main valve P port pressure P_P(t) is increased; when the electric control pump proportional valve Y1 current value is reduced, the main valve P port pressure P_P(t) decrease;

the basis functions for PID control of the electrical load sensing system are as follows:

wherein the proportionality coefficient K_pIntegral coefficient K_IAnd a differential coefficient K_DFor a set value, the controller periodically collects P according to a PID algorithm_P(t) and P_L(t) periodically calculating the deviation e (t);

setting delta P, periodically adjusting the current value of the proportional valve Y1 of the electric control pump, and further adjusting the pressure P of the main valve P port_P(t) where e (t) is 0. Preferably, the electronically controlled pump proportional valve Y1 is an electrically proportional pressure control valve.

The invention achieves the following beneficial effects:

the invention aims to provide an electric load sensitivity control method which can be applied to an aerial work platform, and elaborates the basic principle and the implementation method of an electric load sensitivity technology. The pressure sensor signals of the main valve port P and the load pressure port are collected through the controller, and the pressure difference between the main valve port P and the load pressure port is controllable by utilizing a PID control algorithm and adjusting the output current value of the electric control pump proportional valve. The invention realizes the application of the electric load sensing technology to the aerial work platform, increases the speed regulation range of the main action, improves the micro-mobility of the operation, and has small influence of the action speed on the environmental temperature.

Drawings

FIG. 1 is a functional block diagram of the present invention;

FIG. 2 is a hydraulic schematic of the present invention;

FIG. 3 is a schematic diagram of an electrical load sensitive control method of the present invention;

FIG. 4 is a flow chart of an electrical load sensitivity control method of the present invention;

figure 5 is a schematic view of an aerial work platform.

In the attached drawings, 1, a rotary table; 2. a platform; 3 main arm.

Detailed Description

The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.

It should be noted that, if there is a directional indication (such as up, down, left, right, front, and back) in the embodiment of the present invention, it is only used to explain the relative position relationship between the components, the motion situation, and the like in a certain posture, and if the certain posture is changed, the directional indication is changed accordingly.

In addition, if the description of "first", "second", etc. is referred to in the present invention, it is used for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

As shown in fig. 1, the hardware of the electronic control system of the invention comprises a pressure sensor YP1, a pressure sensor YP2, a controller, an electronic control pump proportional valve Y1 and a main arm variable amplitude proportional valve Y2, wherein the main arm variable amplitude proportional valve Y2 is a three-position seven-way proportional solenoid valve, and the main arm variable amplitude proportional valve Y2 comprises a main arm lower variable amplitude coil Y2a and a main arm upper variable amplitude coil Y2 b.

As shown in fig. 2, the electronic control pump proportional valve Y1 is used for controlling the inclination angle of the swash plate of the electronic control pump, the pressure sensor YP1 and the pressure sensor YP2 are respectively used for acquiring pressure signals of the main valve P port and the load LS port, and the main arm lower variable-amplitude coil Y2a and the main arm upper variable-amplitude coil Y2b of the three-position seven-way proportional solenoid valve are respectively used for controlling retraction and extension of the variable-amplitude oil cylinder, that is, the main arm lower variable-amplitude and upper variable-amplitude.

As shown in FIG. 2, the simplified main valve of the present invention mainly comprises a head-coupling, an operating-coupling and a tail-coupling, and the number of the operating-couplings can be increased according to the needs of the functions, such as the extension function coupling of the main arm and the rotation function coupling of the turntable, etc., when the vehicle is in use.

In the control of an actual vehicle, the main operation that an aerial work platform needs an electric control pump to supply oil comprises the following steps: the invention discloses a main arm luffing mechanism, a main arm stretching mechanism, a rotary table rotating mechanism, a platform leveling mechanism, a platform rotating mechanism and a crank luffing mechanism.

The inlet of the electric control pump is connected with an oil tank, and the outlet of the electric control pump is connected with a port P of the main valve; the oil discharge T port of the main valve is connected with an oil tank, the LS port and the P port are respectively connected with two pressure sensors, and the A1 port and the B1 port are respectively connected with two inlets of a balance valve on the luffing cylinder. In the invention, the current of the proportional valve Y1 of the electric control pump is increased, the pressure of the outlet of the electric control pump is gradually increased, the pressure of the P port is increased after the pressure loss of a section of long pipeline, and at the moment, after the lower amplitude coil Y2a of the main arm of the three-position seven-way proportional electromagnetic valve or the upper amplitude coil Y2b of the main arm is opened, the amplitude-variable oil cylinder retracts or extends out, and the whole vehicle shows the lower amplitude or the upper amplitude of the main arm.

In order to realize that the flow passing through the main arm variable amplitude proportional valve is not influenced by load change and increases approximately proportionally with the increase of the coil current of the main arm variable amplitude proportional valve, a proportional flow control valve with fixed pressure difference is adopted. The main valve is designed into a thin blade type liquid resistance, and the flow pressure characteristic of the main valve meets the following formula:

ΔP＝P_P-P_L (2)

wherein Q-the flow through the main arm variable amplitude proportional valve, m³/s；

C_d-a flow coefficient;

a-flow area of main arm variable amplitude proportional valve, m²；

Delta P is the pressure difference Bar generated by the liquid flowing through the variable amplitude proportional valve of the main arm;

rho-liquid density, kg/m³；

P_P-main valve P port pressure value, Bar;

P_L-load LS port feedback pressure value, Bar;

DeltaP is the main valve P port pressure P as shown in equation (2)_PAnd load feedbackPressure P_LThe difference, the flow coefficient C shown in formula (1)_dAnd the liquid density rho is a fixed value, and if delta P is fixed, in order to realize that the flow passing through the main arm variable-amplitude proportional valve is not influenced by load change, the flow of the main arm variable-amplitude proportional valve is increased along with the approximate proportion of the flow area A of the main arm variable-amplitude proportional valve.

FIG. 3 shows an electrical load-sensitive control scheme, with a main valve P-port pressure P_P(t) and load feedback pressure P_L(t) signal acquisition by the controller in real time, Δ P_sIs a settable system pressure differential. e (t) ═ P_P(t)-P_L(t))-ΔP_s，ΔP_sFor constant value, load feedback pressure P_L(t) dynamically varying with load, the control objective being to bring the deviation e (t) towards 0 at each cycle of the program, where it is necessary to adjust the pressure P of the main valve P-port in real time_P(t) of (d). The control object of the invention is an electric control pump proportional valve Y1, when the Y1 current value increases, the pressure P of the main valve P port_P(t) increase, main valve P port pressure P when Y1 current value decreases_P(t) decrease, how large current values are best provided for Y1 during each program cycle, the present invention introduces a PID algorithm.

The PID algorithm mainly comprises a proportional link, an integral link and a differential link, and the classical theoretical formula of PID control is as follows:

if the program programming needs to be changed into a discrete PID formula:

Δu(n)＝K_pe(n)+K_I[e(n)+e(n-1)+...+e(0)]+K_D[e(n)-e(n-1)](4)

proportionality coefficient K in PID algorithm_pIntegral coefficient K_IAnd a differential coefficient K_DAnd obtaining in the field debugging process. The controller periodically collects P according to a PID algorithm_P(t)、P_L(t) and periodically calculating the deviation e (t), periodically adjusting the output current value of the electrically controlled pump proportional valve Y1 so that e (t) is equal to 0, and further adjusting the main valve P port pressure P_P(t) is changed. To reach the main valve PMouth pressure P_P(t) good following performance and high precision of system pressure difference delta P.

FIG. 4 is a flow chart of the electrical load sensing control method, system pressure setting Δ P_sCoefficient of proportionality K_pIntegral coefficient K_IAnd a differential coefficient K_DFor known quantities, the controller collects the pressure P at the main valve P port_P(t) and load feedback pressure P_L(t), calculating deviation value e (t) ═ P_P(t)-P_L(t))-ΔP_sCalculating a proportional error value Deltau_P＝K_Pe (t), calculating an integral error value delta u_I＝K_I[e(t)+e(t-1)+...+e(0)]Calculating a differential error value Deltau_D＝K_D[e(t)-e(t-1)]Calculating the control amount Δ u ═ Δ u_P+Δu_I+Δu_DAn error current value of Δ u is given to the controlled object electric control pump proportional valve Y1 through the output port of the controller, the main valve P port pressure is periodically changed, the controller prepares for PID control in the next period, e (t-1) is given to e (t-2), and e (t) is given to e (t-1).

According to the formula (1), the electric control load sensing system can realize speed regulation by adjusting the opening of the proportional valve and adjusting the differential pressure at the same time, and improves the speed regulation range of the main action.

After the opening of the proportional valve is adjusted to the minimum value, the electronic control load sensing system can further adjust the pressure difference between the P opening of the main valve and the load, and improves the micro-mobility of the main action.

1) The invention provides an electric load sensitive control technology, which adopts two paths of pressure sensors, wherein one path is connected with a load feedback oil path, and the other path is connected with a P port of a main valve.

2) The invention provides an electric load sensitive control technology, which adopts a classical PID control technology to realize the stability of the pressure difference between a main valve P port and a load.

3) In the invention, the pressure difference between the main valve P port and the load can be set by a program, so that the dynamic pressure difference control between the main valve P port and the load in the system can be realized, the speed regulation range of the main action is improved, and the micro-property of the main action is improved.

4) The two pressure sensors are respectively connected with the P port of the main valve and the load feedback oil circuit, and the theoretical basis that the main operating speed is not influenced by temperature or is slightly influenced is explained.

5) The electric load sensitive control method not only can realize the static control that the system pressure difference delta P reaches a certain set value, but also can realize the dynamic control that the system pressure difference delta P changes along with the set pressure difference.

As can be seen from the formula (1), the operation speed is mainly determined by the opening area of the proportional valve and the differential pressure Δ P before and after the proportional valve, and the opening area of the proportional valve can be realized by adjusting the current value of the proportional valve. The PID control algorithm can realize the stability of the differential pressure delta P before and after the proportional valve, and the influence of the temperature on the action speed is theoretically absent or has little influence.

The pressure sensor YP1, pressure sensor YP2, controller, automatically controlled pump proportional valve Y1, three-position seven-way proportional solenoid valve, check valve, overflow valve, automatically controlled pump, choke valve, single piston rod jar and two-position three-way valve, the model that can adopt in prior art is many, and the suitable model can be selected according to actual demand by the technical staff in the art, and this embodiment is no longer exemplified one by one.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.