CN109211451B - A method for measuring friction force of a hydraulically driven ship lift system - Google Patents

Abstract

The invention discloses a method for measuring friction force of a hydraulically driven ship lift system, and belongs to the field of channel engineering monitoring. The method specifically comprises the following steps: (1) installing a sensor; (2) measuring and calculating the buoyancy and buoyancy process of the ship chamber in the upward direction; (3) measuring and calculating the downward buoyancy and buoyancy process of the ship chamber; (4) calculating the friction force of the ship compartment at the same elevation; (5) averaging the friction force obtained in the step (4); (6) finally obtaining a relation line of the friction force of the hydraulically driven ship lift and the ship chamber elevation position. The invention has the beneficial effects that: the method for measuring the friction force of the hydraulic ship lift system by using the buoyancy is novel, simple in principle, easy to implement and accurate and reliable in data; the number of measuring elements is small, and a sensor is only required to be arranged on one side of the winding drum; the system friction of the full-stroke ship lift can be obtained.

Description

A method for measuring friction force of a hydraulically driven ship lift system

technical field

The invention relates to a method for measuring the friction force of a hydraulically driven ship lift system, in particular to a direct measurement method for the frictional force of a hydraulically driven ship lift system, and belongs to the field of channel engineering monitoring.

Background technique

The ship lift is a channel that can overcome the large head difference and provide a fast passage for the ship to pass the dam. Germany, Belgium and other European countries have a relatively high level of construction technology for large ship lifts. my country's large ship lifts started relatively late, but they have developed rapidly in recent years. A number of representative large ship lifts have been built one after another, creating a number of world most. The largest rack-and-pinion ship lift of the Yangtze River Three Gorges has been put into trial operation in September 2016. The maximum lifting weight is 15500t, the maximum lifting height is 113m, and the effective water area of the cabin is 120m×18m×3.5m (length×width×water depth) , which can pass 3000t large ships; Wujiang Goupitan steel wire rope winch ship lift with the largest single-stage lifting height, with a maximum lifting height of 127m, can pass 500t ships, and is currently being installed and commissioned; my country's original Jinghui power-driven ship lift The machine was commissioned in August 2016 and can pass 500t ships. It is also the largest cabin-launched ship lift built in my country. The above three ship lifts are the representatives of the three main types of large vertical ship lifts at present.

The friction force of the ship lift system has always been the concern of the design unit and the operation department. The influence of system friction on the design and operation of the ship lift is mainly reflected in the following aspects: the selection of the lifting mechanism in the design process, the wear and tear of the friction force on the mechanical system, the influence of the friction force superimposed on other loads on the safety of the ship lift, etc. Driven boat lifts, pontoon size and water distribution are also limited by friction.

There are many friction measurement methods. The simplest friction measurement method is introduced in the junior high school physics textbook. The friction measurement method uses a spring balance to pull a wooden block to make a uniform linear motion. Among the related friction force measurement methods, there are many literatures on cylinder friction force measurement. The measurement methods are roughly divided into two types. One is to use air pressure drive to measure the pressure of the intake cavity and exhaust cavity at both ends of the piston in real time, and to indirectly calculate the static and dynamic friction forces according to the balance equation between the friction force and the air pressure on the piston. , which can be called the indirect measurement method of the friction force of the cylinder; the second is to use external traction drive, the external driving element and the cylinder are connected through a force sensor, the output of the force sensor is collected, and the static and dynamic friction forces of the cylinder are obtained in combination with the equation of motion. This method is called direct measurement.

The water-driven ship lift is a new type of ship lift independently developed by my country, and its related mechanical properties need to be obtained through direct monitoring. The main drawbacks of the prior art are:

(1) The water-driven ship lift is a new type of ship lift. Its friction mainly includes the reel and the reel support, the synchronous shaft and the bearing support, the guide wheel of the ship and the guide rail of the ship lift. The friction force between them is the rolling friction force. There are many components of friction force, and the influencing factors are complex, and there is no suitable method to measure it.

(2) The traditional measurement methods are all aimed at the hoisting ship lift. The tension gauge is directly installed on the wire rope to measure, which is complicated in technology and has a great impact on the normal operation of the ship lock.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a method for measuring the friction force of a hydraulically driven ship lift system, so as to obtain the magnitude of the system frictional force of the hydraulically driven ship lift.

The technical scheme of the present invention to achieve the above object is: a method for measuring the friction force of a hydraulically driven ship lift system. Considering the friction force of the ship lift from the whole system of the ship lift, a water level sensor is arranged at the bottom of the shaft and a laser displacement sensor is arranged at the top of the shaft , by monitoring the data of the water level of the shaft and the position of the buoy during the constant speed up and down or reversing of the ship lift, calculate the change of the buoyancy of the buoy, and then convert it into the friction force of the ship lift system.

A method for measuring the friction force of a water-driven ship lift system, and the principle of realizing the system friction force measurement is:

(1) During the upward, downward and reverse process of the cabin at a constant speed, the buoyancy of the buoy changes due to the hindering effect of the system friction on the relative operation;

(2) Monitoring the water surface of the shaft and the position of the buoy, the buoyancy change of the buoy can be obtained;

(3) Convert the buoyancy buoyancy that changes according to the time series into the buoyancy buoyancy that changes according to the height of the cabin, and obtain the change value of the buoyancy at the same elevation through the difference between the buoyancy of the upward and downward buoys at the same cabin elevation;

(4) The change value of the buoyancy of the buoy at the same elevation during the up, down and reversing process of the cabin is 4 times the system friction force, and the initial full stroke system friction force of the cabin can be obtained.

(5) In order to solve the problem that the acceleration operation of the cabin during the valve opening process does not meet the uniform speed condition during the up and down process, considering that the valve opening time is short and the acceleration effect has a short effect on the running distance of the cabin, the preliminary system friction calculated for the up and down The force is averaged for every 5m of elevation to obtain the system friction force at that elevation.

The present invention is a method for measuring friction force of a water-driven ship lift system, comprising the following steps:

(1) Install sensors; specifically, install a water level sensor at the bottom of the shaft, and install a laser displacement sensor at the top of the shaft; the water level sensor at the bottom of the shaft is used to measure the water level of the shaft, and the laser displacement sensor at the top of the shaft is used to measure the top of the buoy to the placement position of the laser displacement sensor the distance between;

(2) Measure and calculate the upward buoyancy and buoyancy process of the cabin; the cabin starts to move upward, the water level sensor collects the water surface elevation of the shaft at a frequency of 1Hz-100Hz, and obtains the time change curve of the water level of the collection well; the laser displacement sensor collects the top of the buoy at a frequency of 1Hz-100Hz The distance to the laser displacement sensor is obtained, and the distance-time curve from the buoy to the laser displacement sensor is obtained;

The height of the buoy is obtained by subtracting the elevation of the water surface of the buoy from the top of the buoy to obtain the water outlet height of the buoy. The buoyancy depth can be obtained by subtracting the total height of the buoy from the water outlet height of the buoy, based on which the buoyancy of the buoy can be calculated;

F _u =ρ(h ₁ -(h _2u -h _3u ))sg+F _v (a)

Among them, F _u is the buoyancy force on the buoy when the cabin is going up, h ₁ is the height of the buoy cylinder section, h _2u is the elevation of the buoy during the up-going period of the cabin, h _3u is the water surface elevation of the shaft during the up-going period of the cabin, and s is the section of the cylinder section of the buoy. area, g is the acceleration of gravity, ρ is the density of the water body; the buoy Fv is the buoyancy of the non-cylindrical section of the buoy, and this section has been underwater. The relationship between the upward _buoyancy Fu and the running position of the cabin is established to form a curve of the upward _buoyancy Fu with the upward position of the cabin;

(3) Measure and calculate the downward buoyancy and buoyancy process of the cabin; the cabin starts to descend, the water level sensor collects the water surface elevation of the vertical shaft at a frequency of 1Hz-100Hz, and obtains the time change curve of the water level of the collection well; the laser displacement sensor collects the top of the buoy at a frequency of 1Hz-100Hz. The distance to the laser displacement sensor is obtained, and the distance-time curve from the buoy to the laser displacement sensor is obtained;

The height of the buoy is obtained by subtracting the elevation of the water surface of the buoy from the top of the buoy to obtain the water outlet height of the buoy. The buoyancy depth can be obtained by subtracting the total height of the buoy from the water outlet height of the buoy, based on which the buoyancy of the buoy can be calculated;

F _d =ρ(h ₁ -(h _2d -h _3d ))sg+F _v (b)

where F _d is the buoyancy of the buoy during the downward movement of the cabin, h ₁ is the height of the buoy cylinder section, h _2d is the elevation of the buoy during the downward movement of the cabin, h _3d is the water surface elevation of the shaft during the downward movement of the cabin, and s is the cross-sectional area of the buoy cylinder section, g is the acceleration of gravity; from this, the buoyancy of the buoy F _d is obtained when the cabin goes down; ρ is the density of the water body, and F _v is the buoyancy of the non-cylindrical section of the buoy, and this section is always underwater.

The relationship between the downward buoyancy F _d and the running position of the cabin is established to form a curve of the downward buoyancy F _d with the position of the cabin;

(4) Calculate the friction force of the cabin at the same elevation as:

where T is the tension of the wire rope on the side of the cabin, where T _d is the tension of the wire rope during the downward movement, _Tu is the wire rope tension during the upward movement, M is the mass of the buoy, g is the acceleration of gravity, F _d is the _buoyancy of the buoy during the downward movement of the cabin, and Fu is the buoyancy of the cabin. When going up, it is the buoyant buoy on the buoy, and f is the system friction;

(5) The initial friction force is averaged at every 5m elevation to eliminate the influence of the acceleration during the valve opening process, and then the system friction force at a certain elevation during the up and down process is obtained;

(6) During the reversing process, since the position of the buoy does not change, only the water level of the shaft changes, and the friction force of the ship lift system becomes static friction force, so it does not need to consider the influence of acceleration.

The present invention has the following advantages:

(1) The present invention provides a brand-new method for measuring the friction force of the hydraulic ship lift system extremely simply by using the buoyancy method;

(2) There are few measuring elements, and only the sensor needs to be arranged on one side of the reel;

(3) The system friction force of the full-stroke ship lift can be obtained, and the system friction force of the whole operation of the hydraulic-driven ship lift can be deeply understood, and the theoretical guidance for the design and operation mode of the ship lift is played.

Description of drawings

Fig. 1 is a schematic diagram of the principle of a hydraulically driven ship lift of the method of the present invention;

Fig. 2 the water level of the shaft of the hydraulically driven ship lift of the method of the present invention-time course;

Fig. 3 water-driven ship lift buoy elevation-time course of the method of the present invention;

Fig. 4 the water-driven ship lift cabin elevation-time history line of the method of the present invention;

Fig. 5 is the relationship line between the buoyancy of the buoyancy of the water-driven ship lift of the present invention and the elevation of the cabin;

FIG. 6 is the relationship line between friction force and cabin elevation of the hydraulic drive ship lift system according to the method of the present invention.

Detailed ways

Embodiments are given below in conjunction with the accompanying drawings and the present invention is described in detail.

Example 1

Figure 1 is a schematic diagram of a water-driven ship lift, Figure 2 is a schematic diagram of the downward force of the water-driven ship lift, and Figure 3 is a schematic diagram of the upward force of the water-driven ship lift. 1 is the drum, 2 is the shaft, 3 is the buoy, 4 is the cabin, 5 is the water surface of the shaft, 6 is the wire rope, 7 is the movable pulley, 13 is the water level sensor, and 14 is the laser displacement sensor.

The downward process of the water-driven ship lift is to fill the shaft 2 with water, the water level of the shaft 5 rises to drive the buoy 3 to rise, the cabin 4 and the buoy 3 are connected by the wire rope 6 around the drum 1, the buoy 3 rises, and the cabin 4 is driven to descend, This process is the downward process of the ship lift, and the upward process is the opposite.

The present invention is a method for measuring friction force of a water-driven ship lift system, the steps are as follows

(1) Install the sensor; arrange the water level sensor 13 at the bottom of the shaft 2, and install the laser displacement sensor 14 at the top of the shaft 2, see accompanying drawing 1, the water level sensor 13 at the bottom of the shaft 2 is used to measure the water level of the shaft 2, and the laser displacement sensor at the top of the shaft 2 14 is used to measure the distance from the top of the buoy 3 to the arrangement position of the laser displacement sensor 14;

(2) Measure and calculate the upward buoyancy and buoyancy process of the cabin 4; the cabin 4 starts upward, the water level sensor 13 collects the water surface elevation of the shaft 2 at a frequency of 1Hz-100Hz, and obtains the time change curve of the water level of the collection well; the laser displacement sensor 14 uses a frequency of 1Hz-1Hz- The distance from the top of the buoy 3 to the laser displacement sensor 14 is collected at a frequency of 100 Hz, and the distance-time variation curve from the buoy 3 to the laser displacement sensor 14 is obtained;

The height of the top of the buoy 3 minus the water surface elevation of the shaft 2 is the water outlet height of the buoy 3, and the total height of the buoy 3 minus the water outlet height of the buoy 3 can be obtained. The water entry depth of the buoy 3 can be calculated according to the buoyancy of the buoy;

F _u =ρ(h ₁ -(h _2u -h _3u ))sg+F _v (a)

Among them, F _u is the buoyancy of the buoy when the cabin goes up, h ₁ is the height of the buoy cylinder section, h _2u is the elevation of the buoy during the up-going period of the cabin, h _3u is the water surface elevation of the shaft during the up-going period of the cabin, and s is the section of the buoy cylinder section. area, g is the acceleration of gravity, ρ is the density of the water body; F _v is the buoyancy of the non-cylindrical section of the buoy, and this section has been underwater.

(3) Measure and calculate the downward buoyancy and buoyancy process of the cabin 4; the cabin 4 starts to descend, the water level sensor collects the water surface elevation of the shaft 2 at a frequency of 1Hz-100Hz, and the time change curve of the shaft water level is obtained as shown in Figure 4; -100Hz frequency collects the distance from the top of the buoy 3 to the laser displacement sensor 14, and obtains the distance-time variation curve from the buoy 3 to the laser displacement sensor 14;

The height of the top of the buoy 3 minus the water surface elevation of the shaft 2 is the water outlet height of the buoy 3, and the total height of the buoy 3 minus the water outlet height of the buoy 3 can be obtained. The water entry depth of the buoy 3 can be calculated according to the buoyancy of the buoy;

F _d =ρ(h ₁ -(h _2d -h _3d ))sg+F _v (b)

where F _d is the buoyancy of the buoy during the downward movement of the cabin, h ₁ is the height of the cylinder section of the counterweight, h _2d is the elevation of the buoy during the downward movement of the cabin, h _3d is the water surface elevation of the shaft during the downward movement of the cabin, and s is the cross-sectional area of the cylinder section of the buoy, g is the acceleration of gravity; from this, the buoyancy of the buoy F _d is obtained when the cabin goes down; ρ is the density of the water body, and F _v is the buoyancy of the non-cylindrical section of the buoy, and this section is always underwater.

(4) Calculate the friction force of the cabin at the same elevation as:

where T is the tension of the wire rope on the side of the cabin, M is the mass of the buoy, g is the acceleration of gravity, F _d is the buoyancy of the buoy during the downward movement of the cabin, F _u is the buoyancy of the buoy when the cabin goes up, and f is the system friction;

(5) The initial friction force is averaged at every 5m elevation to eliminate the influence of the acceleration during the valve opening process, and then the system friction force at a certain elevation during the up and down process is obtained;

(6) During the reversing process, since the position of the buoy does not change, only the water level of shaft 2 changes, and the friction force of the ship lift system becomes static friction force, so it does not need to consider the influence of acceleration.

Embodiment 2

Taking a water-driven ship lift as an example, the buoy height of the ship lift is 16.8m, the annular gap area between the shaft and the buoy is 30.19m, and the volume of the cone at the bottom of the buoy is 18m ³ . There are 16 buoys in total. The friction measurement steps of the ship lift system are as follows:

(1) Install sensors; specifically, install a water level sensor at the bottom of the shaft, and install a laser displacement sensor at the top of the shaft; the water level sensor at the bottom of the shaft is used to measure the water level of the shaft, and the laser displacement sensor at the top of the shaft is used to measure the top of the buoy to the placement position of the laser displacement sensor the distance between;

(2) Measure and calculate the upward buoyancy and buoyancy process of the cabin; the cabin starts to move upward, the water level sensor collects the water surface elevation of the shaft at a frequency of 100Hz, and obtains the time change curve of the water level of the collection well, as shown in Figure 4; the laser displacement sensor collects the buoy at a frequency of 100Hz. The distance from the top to the laser displacement sensor, the buoy elevation-time change curve is obtained, as shown in Figure 3. At the same time, since the wire rope connects the buoy and the cabin, according to the length of the wire rope, the buoy elevation-time change curve can be converted into the cabin elevation time change curve, see Figure 4;

The height of the buoy is obtained by subtracting the elevation of the water surface of the buoy from the top of the buoy to obtain the water outlet height of the buoy. The buoyancy depth can be obtained by subtracting the total height of the buoy from the water outlet height of the buoy, based on which the buoyancy of the buoy can be calculated;

F _u =ρ(h ₁ -(h _2u uh _3u ))sg+F _v (a)

Among them, F _u is the buoyancy of the buoy when the cabin goes up, h ₁ is the height of the buoy cylinder section, h _2u is the elevation of the buoy during the up-going period of the cabin, h _3u is the water surface elevation of the shaft during the up-going period of the cabin, and s is the section of the buoy cylinder section. area, g is the acceleration of gravity, ρ is the density of the water body; F _v is the buoyancy of the non-cylindrical section of the buoy, and this section is always underwater; the relationship between the upward buoyancy Fu and the running position of the cabin is established to form the upward buoyancy _{Fu u along} with the ship The change curve of the height of the car is shown in Figure 5;

(3) Measure and calculate the downward buoyancy and buoyancy process of the cabin; the cabin starts to descend, the water level sensor collects the water surface elevation of the shaft at a frequency of 100Hz, and obtains the time change curve of the water level of the collection well; the laser displacement sensor collects the top of the buoy to the laser displacement sensor at a frequency of 100Hz The distance from the buoy to the laser displacement sensor-time curve is obtained;

The height of the buoy is obtained by subtracting the elevation of the water surface of the buoy from the top of the buoy to obtain the water outlet height of the buoy. The buoyancy depth can be obtained by subtracting the total height of the buoy from the water outlet height of the buoy, based on which the buoyancy of the buoy can be calculated;

F _d =ρ(h ₁ -(h _2d -h _3d ))sg+F _v (b)

where F _d is the buoyancy of the buoy during the downward movement of the cabin, h ₁ is the height of the cylinder section of the counterweight, h _2d is the elevation of the buoy during the downward movement of the cabin, h _3d is the water surface elevation of the shaft during the downward movement of the cabin, and s is the cross-sectional area of the cylinder section of the buoy, g is the acceleration of gravity; from this, the buoyancy of the buoyancy F _d is obtained when the cabin goes down; ρ is the density of the water body, F _v is the buoyancy of the non-cylindrical section of the buoy, and this section is always underwater _; A relationship is established to form a curve of downward buoyancy F _d with the elevation of the cabin, as shown in Figure 5;

(4) Calculate the friction force of the cabin at the same elevation as:

Among them, T is the tension of the wire rope on the side of the cabin, M is the mass of the buoy, g is the acceleration of gravity, Fd is the buoyancy of the buoy during the downward movement of the cabin, Fu is the buoyancy of the buoy when the cabin is up, and f is the system friction;

(5) The initial friction force is averaged at every 5m elevation to eliminate the influence of the acceleration during the valve opening process, and the system friction force at a certain elevation during the up and down process is obtained, as shown in Figure 6;

(6) During the reversing process, since the position of the buoy does not change, only the water level of the shaft changes, and the friction force of the ship lift system becomes static friction force, so it does not need to consider the influence of acceleration. The position relationship line is shown in Figure 6.

Claims (3)

1. A method for measuring the friction force of a hydraulically driven ship lift system is characterized by comprising the following steps: the method comprises the following steps:

(1) installing a sensor; the method specifically comprises the steps that a water level sensor is installed at the bottom of a vertical shaft, and a laser displacement sensor is installed at the top of the vertical shaft;

(2) measuring and calculating the buoyancy and buoyancy process of the ship chamber in the upward direction; will go upward buoyancy F_uEstablishing a relationship with the running position of the ship chamber to form an upward buoyancy F_uA curve changing along with the ascending position of the ship compartment;

(3) measuring and calculating the downward buoyancy and buoyancy process of the ship chamber; will descend buoyancy F_dEstablishing a relationship with the running position of the ship chamber to form a downward buoyancy F_dA curve changing along with the descending position of the ship compartment;

(4) calculating the friction force of the ship chamber at the same elevation as follows:

wherein T is the tension of the steel wire rope at the side of the ship chamber, wherein T_dFor wire rope tension during descent, T_uFor the wire rope tension during the ascent, M is the buoy mass, g is the gravitational acceleration, F_dFor buoyancy of the pontoon during downward travel of the vessel, F_uThe buoyancy force borne by the buoy when the ship chamber ascends, and f is the system friction force;

(5) averaging the friction force obtained in the step (4) according to the elevation of every 5m to eliminate the influence of acceleration in the opening process of the valve, and obtaining the friction force of the system at a certain elevation in the uplink and downlink processes;

(6) in the reversing process, as the position of the buoy is unchanged and only changes in the water level of the vertical shaft, the friction force of the ship lift system is changed into static friction force, so that the influence of acceleration is not required to be considered, and a relation line between the friction force of the hydraulically driven ship lift and the elevation position of a ship chamber is obtained.

2. The method for measuring the friction force of the hydraulically driven ship lift system according to claim 1, wherein the method comprises the following steps: the method for measuring and calculating the ascending buoyancy and the buoyancy of the ship chamber comprises the following steps: starting the ship chamber to ascend, and acquiring the water level elevation of the vertical shaft by the water level sensor at the frequency of 1Hz-100Hz to obtain a water level time change curve of the acquisition well; the laser displacement sensor collects the distance from the top of the buoy to the laser displacement sensor at the frequency of 1Hz-100Hz to obtain a distance-time change curve from the buoy to the laser displacement sensor; the shaft surface of water elevation is subtracted to the flotation pontoon apical elevation and the flotation pontoon height of going out is obtained, subtracts the flotation pontoon height of going out with the total height of flotation pontoon and can obtain the flotation pontoon depth of going into water, can calculate flotation pontoon buoyancy in view of the above:

F_u＝ρ(h₁-(h_2u-h_3u))sg+F_v(a)

wherein F_uBuoyancy borne by the pontoon when the ship chamber ascends, h₁Is the height of the cylinder section of the buoy h_2uFor the elevation of the pontoon during the ascent of the ship's cabin_3uThe elevation of the water surface of a vertical shaft during the ascending of a ship chamber, s is the sectional area of a cylindrical section of a buoy, g is the gravity acceleration, and rho is the density of a water body; float F_vThe buoy is not buoyant in a cylinder section, and the section is always underwater.

3. The method for measuring the friction force of the hydraulically driven ship lift system according to claim 1, wherein the method comprises the following steps: the method for measuring and calculating the descending buoyancy and the buoyancy process of the ship chamber comprises the following steps: starting the ship chamber to descend, and acquiring the water level elevation of the vertical shaft by the water level sensor at the frequency of 1Hz-100Hz to obtain a water level time change curve of the acquisition well; the laser displacement sensor collects the distance from the top of the buoy to the laser displacement sensor at the frequency of 1Hz-100Hz to obtain a distance-time change curve from the buoy to the laser displacement sensor; subtracting the water surface elevation of the vertical shaft from the top elevation of the buoy to obtain the water outlet height of the buoy, subtracting the water outlet height of the buoy from the total height of the buoy to obtain the water inlet depth of the buoy, and calculating the buoyancy of the buoy according to the water inlet depth of the buoy;

F_d＝ρ(h₁-(h_2d-h_3d))sg+F_v(b)

wherein F_dBuoyancy of the pontoon during the downward movement of the chamber, h₁Is the height of the cylinder section of the buoy h_2dFor the elevation of the pontoon during the downward movement of the ship chamber, h_3dThe elevation of the water surface of the vertical shaft during the descending of the ship chamber, s is a buoy with the sectional area of a buoy barrel section, and g is gravity acceleration; thereby obtaining the buoyancy F of the buoy when the ship chamber goes down_d(ii) a ρ is the density of the water body, F_vThe buoy is not buoyant in a cylinder section, and the section is always underwater.

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