RU2110047C1 - Method of feremination of load mass in transport facility - Google Patents

Abstract

FIELD: various branches of industry and transport. SUBSTANCE: method includes measurement of vertical movement of load-receiving platform, in process of its loading or unloading in at least three states of loaded transport facility. Additional measurements of platform vertical movement are performed with standard load of preset mass superposed in each of loaded states. Load mass in transport facility is calculated from formula derived on the basis of Hooke's law. Method has the following advantages: higher accuracy of measurements conditioned by accuracy of measurement of standard load mass and by error platform vertical movement indicator; low cost of measuring device and equipment, as compared with stationary platform-type balance; absence of periodic calibration and check-up operations; weighing of load directly at points of its loading and unloading. EFFECT: higher measurement accuracy. 3 cl, 1 dwg

Description

 The invention relates to weighing equipment and can be used in various industries and vehicles to determine the mass of bulk (sand, flour, cement, etc.) and bulk (liquefied gas, petroleum products, milk, chemicals, etc.) cargo when loading or unloading a vehicle.

A known method and device for weighing vehicles based on the registration of the output signals of several horizontally spaced load transducers installed between the load platform and the foundation. The upper end of each transducer holds the platform, and the lower is on the base support element [1]. When implementing this method, the mass of the cargo is determined by weighing the filled and empty vehicle and subtracting the obtained values:
M = M _p - M _g ,
Where
M is the mass of the cargo in the vehicle;
M _p - the mass of the vehicle loaded with cargo;
M _g - the mass of the emptied vehicle (tare).

 The disadvantage of this method is the bulkiness and high cost of the equipment necessary for its implementation (the construction of a monolithic foundation, the need for periodic prevention, calibration and calibration of power transducers), as well as the high cost of time and money to move the vehicle from the place of loading or unloading to the weight measuring device.

 Of the known methods, the closest in technical essence to the invention is a method based on measuring the vertical movement of the cargo receiving platform of the vehicle relative to its axles due to the deformation of the springs installed between the platform and the axles (prototype) [2]. The vertical movement of the platform is measured by an induction type sensor that generates an electrical signal characterizing the relative position of the two sensor elements associated with the platform and the axis of the vehicle. Also known are technical solutions for implementing this method using strain gauge [3], resistive [4], magnetic [5] and optical [6] displacement sensors.

 The disadvantages of this method are the need for calibration and periodic verification of displacement sensors, as well as low weighing accuracy, due to the fact that the stiffness coefficient of the springs can change during operation of the vehicle and as a result of seasonal temperature changes.

 The aim of the present invention is to improve the accuracy of determining the mass of the cargo, the cost of measuring equipment and the possibility of weighing the goods directly in places of loading or unloading, not equipped with stationary platform scales.

где
М - масса груза в транспортном средстве;
m - масса эталонного груза;
n - количество состояний загруженности транспортного средства, в которых проводят измерения вертикального перемещения;
δ_i - вертикальное перемещение платформы при наложении эталонного груза в i-м состоянии загруженности;
d_i= (δ_i+δ_i-1)/2 - среднее вертикальное перемещение платформы при наложении эталонного груза между i и i-1-м состоянием загруженности;

- максимальная величина вертикального перемещения платформы при полной выгрузке;
l_o - расстояние от базисной точки платформы до уровня дорожного полотна для заполненного транспортного средства;
l_n - расстояние от базисной точки платформы до уровня дорожного полотна для порожнего транспортного средства;
до основания 13 для порожней цистерны;
L_i = (L_i-L_i-1) - изменение расстояния от базисной точки платформы до уровня дорожного полотна между i и i-1-м состоянием загруженности;
ΔM - абсолютная погрешность определения массы груза М.To achieve the solution of the goal in a method of determining the mass of a cargo in a vehicle, including measuring the vertical movement of the cargo receiving platform during loading or unloading of the vehicle, the vertical movement is measured in at least three states of the vehicle’s load, and the vertical movement of the platform is additionally measured when applying a reference load of a given mass in each of the states of congestion, and the mass of the load is calculated according to the forms le:

Where
M is the mass of the cargo in the vehicle;
m is the mass of the reference load;
n is the number of vehicle congestion states in which vertical displacement measurements are taken;
δ _i - vertical movement of the platform when applying the reference load in the i-th state of congestion;
d _i = (δ _i + δ _i-1 ) / 2 - average vertical movement of the platform when applying the reference load between the i and i-1-m state of congestion;

- the maximum value of the vertical movement of the platform at full unloading;
l _o - the distance from the base point of the platform to the level of the roadway for a filled vehicle;
l _n is the distance from the base point of the platform to the level of the roadway for an empty vehicle;
to base 13 for an empty tank;
L _i = (L _i -L _i-1 ) - change in the distance from the base point of the platform to the level of the roadway between i and i-1st state of congestion;
ΔM is the absolute error in determining the mass of cargo M.

где

- относительная погрешность измерения величины вертикального перемещения l;

- относительная погрешность измерения массы эталонного груза;

- относительная погрешность измерения среднего вертикального перемещения d.The relative error in determining the mass of the cargo ε _{M is} calculated by the formula;

Where

- the relative measurement error of the magnitude of the vertical displacement l;

- the relative error in measuring the mass of the reference load;

- relative error in measuring the average vertical displacement d.

Here ΔL, Δm, Δd are the absolute measurement errors of the corresponding quantities L, m, d (it is assumed that d = d ₁ = = d ₂ = ... = d _n = d _min ; L = L ₁ = L ₂ = .. . = L _n = L _max ).

где
M^* - ожидаемая масса груза (грузоподъемность транспортного средства, указанная в его паспорте);

- требуемое значение относительной погрешности определения массы груза М;

- реальные значения относительных погрешностей измерения величин L, m и d.The choice of the mass of the reference load m is made according to the formula:

Where
M ^* is the expected mass of the cargo (vehicle carrying capacity indicated in its passport);

- the required value of the relative error in determining the mass of the cargo M;

- real values of the relative measurement errors of the quantities L, m and d.

 The drawing shows a diagram explaining the essence of the method (for example, tanks with bulk cargo). A tank 1 with a bulk cargo 2, equipped with a drain pipe 9, is mounted on a loading platform 3, which, through a system of springs 5, is supported on wheelsets 4 mounted on a rail grate (rails 6 and sleepers 7) located on the subgrade 8. Reference load 10 with the help of a lifting device 11 can be superimposed on the tank 1. To measure the vertical displacement of the platform 3, a displacement sensor (indicator) 12 is used, supported by the lower end on the base 13, rigidly connected with the rails 6, and the upper end on the lower plane A- A platform 3.

The method is implemented as follows. For each of i = 0, 1, 2, ..., n states of loading of tank 1 with bulk cargo 2 (i = 0 corresponds to the full load of the tank, i = n corresponds to a completely empty tank) measure the distance l _i from the reference point in plane A -A platform 3 to the base 13 using the sensor 12 (see drawing). These measurements are carried out in the process of emptying (or filling) the tank 1 with a bulk cargo 2 through the pipe 9. In addition, for each of the i = 1,2, ..., n load conditions of the tank 1, the vertical displacement δ _{i is} measured by the sensor 12 (i = 0, 1,2, ..., n) a reference point in the plane AA when applying a reference load 10 to the tank 1 using a lifting device 11 (see drawing). As a result of measurements, two series of quantities are obtained:
l _i (i = 0,1,2, ..., n) - the distance from the base point in the plane AA of the platform 3 to the base 13 under various conditions of loading of the tank;
δ _i (i = 0,1,2, ..., n) - vertical movement of the platform when applying a reference load for various states of loading of the tank.

где

- относительная деформация пружин (вертикальное перемещение);
x_o - длина пружин в отсутствии нагрузки;
x - длина пружин при нагрузке;
E - модуль упругости пружин;
F - M•g - действующая сила (вес нагрузки), g=9,81m•c^-2 - ускорение свободного падения.Within the framework of the elastic deformation model, the dependence of the vertical displacement of the platform upon compression of the spring springs from the load is described by Hooke's law [7]:

Where

- relative deformation of the springs (vertical movement);
x _o - the length of the springs in the absence of load;
x is the length of the springs under load;
E - spring modulus;
F - M • g - effective force (load weight), g = 9.81m • s ^-2 - gravity acceleration.

 The system under consideration includes a number of elastic elements that undergo deformation under load of the tank. This is a system of springs 5, elastic beams of the loading platform 3, rails 6, subgrade 8, etc.

где E_j - модули упругости отдельных элементов системы.With this in mind, Hooke's law should be written as:

where E _j are the elastic moduli of individual elements of the system.

При заданном E_θ , который можно определить, например, для каждого транспортного средства путем градуировки с помощью стационарных железнодорожных весов, определение массы груза М сводится к измерению вертикального перемещения платформы и расчету М по формуле:

где

- вертикальное перемещение при полной выгрузке (или погрузке) цистерны;

- эквивалентный коэффициент жесткости упругой системы (определяется градуировкой).Since the determination of the individual components E _{j is} difficult, it is advisable to replace them with some equivalent modulus of elasticity, assuming the additivity of its individual components:

For a given E _θ , which can be determined, for example, for each vehicle by graduation using a stationary railroad balance, determining the mass of cargo M reduces to measuring the vertical movement of the platform and calculating M according to the formula:

Where

- vertical movement during full unloading (or loading) of the tank;

- equivalent stiffness coefficient of the elastic system (determined by graduation).

The use of formula (8) leads to large errors in determining the mass of the cargo, due to the following factors:
1. The spring stiffness K _{θ is} not the same for different vehicles.

2. The spring stiffness K _{θ is} not the same even for the same vehicle with seasonal changes in temperature (from -40 ^o C to +40 ^o C).

3. The value of K _θ can change as a result of long-term operation of the vehicle (deformation, "fatigue" of the metal, etc. effects).

4. The value of K _θ may have a nonlinear dependence on the state of congestion.

 5. When using formula (8), it is necessary to measure the vertical movement of the platforms on the same section of the railway track, which is not always convenient during loading and unloading operations.

, причем с целью повышения точности его определения берется среднее его значение между i и i-1-м состоянием загруженности

где d_i= (δ_i+δ_i-1)/2 - среднее вертикальное перемещение платформы при наложении эталонного груза между i и i-1-м состоянием загруженности.The proposed method completely eliminates these disadvantages. When implementing this method, the equivalent stiffness coefficient K _θ is determined for each range of elastic deformation

, and in order to increase the accuracy of its determination, its average value is taken between the i and i-1st state of congestion

where d _i = (δ _i + δ _i-1 ) / 2 is the average vertical movement of the platform when applying a reference load between the i and i-1-th state of congestion.

здесь L_i= l_i-l_i-1 - вертикальное перемещение цистерны между i и i-1 состояниями загруженности.Substituting (9) and (8), we obtain the working form for determining the mass of the cargo M:

here L _i = l _i -l _i-1 is the vertical movement of the tank between i and i-1 congestion states.

When implementing this method, the number of congestion states n in which vertical displacements l _i , δ _i are measured should be at least three in order to control the fulfillment of Hooke's law (the greater n, the more accurate the result of determining M). At the same time, for any state of congestion, it is possible to determine the mass of a cargo that has been filled or drained at a given moment by the measured value of l ₁ .

The proposed method has the following advantages:
1. High measurement accuracy, due to the accuracy of the measurement of the mass of the reference load and the error of the indicator of vertical displacement.

 2. Low cost of the measuring device and equipment in comparison with stationary platform scales.

 3. The lack of periodic grading and verification operations.

 4. The possibility of weighing cargo directly at the places of its loading or unloading, not equipped with stationary platform scales.

 The error in determining the mass of the cargo M is found by the standard method [8] by differentiating expression (10).

Предположим, что
d = d₁ = d₂ = ... = d₃ = d_min
L = L₁ = L₂ = ... = L₃ = L_max
В этом случае получим верхнюю оценку погрешности

- относительняае погрешности измерения m, L, d

и тогда

где

- относительные погрешность определения массы груза.

Let's pretend that
d = d ₁ = d ₂ = ... = d ₃ = d _min
L = L ₁ = L ₂ = ... = L ₃ = L _max
In this case, we obtain the upper error estimate

- relative measurement errors m, L, d

and then

Where

- the relative error in determining the mass of the cargo.

получим:

Из (16) выразим величину m:

где
М^* - ожидаемая масса груза (грузоподъемность транспортного средства);

- требуемая относительная погрешность определения массы груза;

- реальные значения относительных погрешностей измерения L и m соответственно.Find the expression for choosing the mass of the reference load. Replacing in (14) the value of d by the formula:

we get:

From (16) we express the value m:

Where
M ^* - the expected mass of the cargo (vehicle capacity);

- the required relative error in determining the mass of the cargo;

- real values of the relative measurement errors L and m, respectively.

 As follows from (16), the higher m, the more accurate will be the result of determining the mass of cargo M. However, an excessive increase in m will necessitate the use of a bulky device for applying m.

 Formula (17) allows you to optimally select one of the main parameters for the implementation of the proposed method is the mass of the reference load m.

Sources of information:
1. Application N 2125175, UK, cl. 6016 19/02. Platform scales. Publication 84.02.29 N 4957.

 2. US patent N 4106579, 6016 19/08. Device for measuring the load on a self-propelled vehicle (prototype). Publication August 15, 1978, T. 973, No. 3.

 3. Application N 1327697, UK, CL 6016 12/12. Publication 73.08.22. N, 4404.

 4. Application N 1288386, Great Britain, cl. 6016 19/12. The electrical method of measuring the load of a vehicle. Publication 72.09.13.

 5. Application N 1292816, UK, cl. 6016 19/12. Libra. Publication 72.10.11.

 6. US patent N 3867990, CL. 6016 19/08. Publication 75.02.25, t. 931, N 4.

 7. Saveliev I.V. The course of general physics, vol. 1.-M .: Nauka, 1982, 432 p.

 8. Kassandrova O.N., Lebedev V.V. Processing the results of observations. -M .: Nauka, 1970, 104 p.

Claims (3)

1. The method of determining the mass of the cargo in the vehicle, based on the measurement of the vertical movement of the loading platform relative to the level of the roadway, characterized in that the vertical movement is measured in n conditions of the vehicle, where n ≥ 3, and additionally measure the vertical movement when applied the reference load of a given mass in the same n states of congestion, and the mass of the load M is calculated by the formula

where m is the mass of the reference load;
n is the number of vehicle congestion states in which vertical displacement measurements are taken;
d _i - average vertical movement of the load receiving platform when applying the reference load in i and (i - 1) congestion state;
L _i - vertical movement of the cargo receiving platform between i and (i - 1) congestion states;
ΔM is the absolute error in determining the mass M of the load. 2. The method according to claim 1, characterized in that it further calculates the relative error in determining the mass M of the cargo by the formula

Where

average relative measurement errors L _i , m, d _i, respectively. 3. The method according to claim 1, characterized in that the mass m of the reference load is determined by the formula

where M ^* is the carrying capacity of the vehicle;

the specified relative error in determining the mass M of the load.