RU2626791C1 - Method for evaluating weight of load lifted and/or moved by lifting-transport device - Google Patents

Abstract

FIELD: transportation.

SUBSTANCE: for evaluating the weight of the load lifted by the lifting and transporting device, a measuring device is used, the magnetic field strength created by a DC traction motor, proportional to the load weight, is measured, the scale of the measuring device is calibrated in weight units.

EFFECT: accuracy of load weight evaluation.

3 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a method for estimating the mass of cargo lifted and / or moved by a lifting and transport device, which is carried out by non-contact measurement of the magnitude of the magnetic field generated by a DC motor.

The present invention relates to the field of material handling equipment, where DC motors are used as motors. Such devices are various hoists, hoists, winches, cranes, elevators, hoists, electric excavators, escalators and other machines that are widely used in industrial and mining enterprises, in construction and in other fields. The present invention can be used to determine the mass of the lifted and / or transported load; it can also be used in control systems and overload protection of cranes, loaders, electric excavators and other machines.

State of the art

The currently known methods for measuring the mass of a load raised by a crane are based on measuring the force acting on the crane structural elements. Depending on the point of application of force, several common weighing schemes can be distinguished:

- weighing on a hook;

- weighing on the traverse;

- weighing of the freight cart;

- measurement of rope tension;

- weighing on the block of pulley pulleys.

The choice of the point of application of force is determined by the purpose of the crane, operating conditions, cargo weight, ease of incorporation of the load-measuring mechanism, etc.

The disadvantages of the above weighing schemes are as follows:

- the need to embed a weighing system under a cargo trolley or under a block of pulley pulleys;

- the need for power supply for the weighing system;

- the need for special devices, winding cables of the communication line with the weighing system.

The following devices are known from the prior art that implement a method of weighing a load based on a measurement of forces.

A device for determining the weight of the cargo of an overhead crane (USSR author's certificate No. 1299947 A1, class B66C 13/16)

The disadvantage of this device is that not only the crane bridge is deformed, but also the wheel pairs of the bridge moving unevenly, the plastic deformation of the paths under the wheel pairs when lifting the load is not taken into account. The device is complex, the measurement accuracy is low.

Crane with measuring system (EP 1806311, class B66C 13/22, publication date 07/11/2007)

The crane contains a trolley, a transceiver mounted on it, which transmits a basic signal and receives a signal from a pulse transceiver, a device for weighing cargo. The pulse transceiver is mounted opposite the crane in a specific place. The crane also contains a device for determining the moment acting on the crane. The disadvantage of this device is the lack of reliability due to the complexity of the device.

A device for determining the weight of the load of an overhead crane (patent RU No. 2381984, class B66C 13/16, publication date 02/20/2010)

The device comprises a linear movement meter for a freight trolley and an indication unit showing the weight of the load. In this case, a constantly stretched cable is used, the straightness of which is maintained constantly regardless of the deflection of the bridge, which is rigidly fixed at one end of the bridge to the crane bridge and connected to the tensioner at the other end, a rod is attached to the middle of the cable, connected to the reading device of the linear displacement meter. The disadvantage is the complexity of the weighing device and, as a consequence, low reliability.

Closest to the proposed technical solution is a solution implemented using a device for weighing goods (patent RU No. 2426077 class G01G, publication date 08/10/20011), which is taken as a prototype.

The device includes a crane beam, a load-transport mechanism, a load-measuring unit with load-measuring load cells of weight loads, a conversion unit electrically connected to load-measuring load cells, and a light display panel displaying weight loads.

The device has two weight measuring units and a beam connecting them, each of the load measuring units consists of a load cell, to which are attached the brackets into which the rings are inserted, the lower ring is mounted on the axis of the lifting block of the crane beam, the upper ring is mounted on the axis of the device beam, a secondary converter is connected to the device beam, connected with an LED display to display the current weight value.

The disadvantages of the prototype are as follows:

- the device has a complex structure of two weighing nodes;

- the need for complex integration of load cells in load cells;

- low reliability of the device and the accuracy of the measurement as a consequence of the complexity of the design and electrical circuit of the device;

- the presence of communication cables for transmitting a signal from a strain gauge.

The present invention is intended to eliminate the above disadvantages.

Disclosure of invention

A fundamentally new non-contact method of weighing goods by the magnitude of the magnetic field generated by the DC motor of a lifting device is proposed.

The technical task of the present invention is to find a fundamentally new non-contact method for estimating the mass of cargo lifted and / or moved by a lifting and transport device, simplifying measurements, not requiring complex and expensive equipment, without interfering with electrical circuits and in the design of a lifting machine and providing sufficient estimation accuracy.

The objectives of the present invention are to facilitate control of the mass of cargo lifted and / or moved by a lifting and transport device, increasing the safety of work and preventing overloading of the lifting and transport devices.

The problem is solved as follows. Contactlessly measured the magnitude of the magnetic field generated by DC motors of the lifting and transport device. As you know, the magnitude of the current consumed by the DC motor is determined by the magnitude of the load on its shaft, which, in turn, depends on the mass of the load and the conditions of movement - rise, descent, horizontal movement, as well as the speed of movement.

The motor current causes a constant, slowly changing, magnetic field, the intensity of which can be measured. The proposed solution uses the well-known relationship between the magnetic field generated by the DC motor and the load on the motor shaft, which determines the mass of the load.

Various sensors can be used for measurement, in particular flux probes. The flux-gate method for measuring tension is quite simple, well studied and allows to achieve the necessary accuracy.

The flux gate has high sensitivity and when measuring strong magnetic fields there is no need to install it in close proximity to the engine or from the power supply circuits of the engine. An ammeter (milliammeter) is used as an indication device, the scale of which is calibrated in units of mass.

In practice, the location of the installation of the flux-gate does not matter - it is only important that it be the same both when calibrating the milliammeter scale and when measuring mass. The milliammeter can be located in almost any convenient place for observation.

Thus, to achieve the claimed technical result, it is necessary:

- To calibrate the milliammeter scale in units of mass;

- to ensure the movement of cargo in the same mode in which the calibration of the scale of the measuring device was performed.

Brief Description of the Drawings

In FIG. 1 shows a differential fluxgate with two permalloy cores with an excitation winding L ₁ consisting of two halves.

In FIG. 2 is a structural diagram of a measuring device by which the method is implemented.

In FIG. 3 shows the inclusion circuit of the flux-gate windings.

The implementation of the invention

Consider FIG. 1. One half of the field winding L ' ₁ is on one core, the other L'' ₁ (wound in the opposite direction to the first) is on the other. The diameter of the field winding wire is 0.3 mm, the number of turns of each half of the field winding 200. The winding is a single-layer turn to a turn. Connects to a pulse generator. The winding L ' ₁ creates a field H and the winding L " ₁ creates the same field H, but directed in the opposite direction.

On top of two cores with windings L ' ₁ and L'' ₁ is a measuring winding L ₂ with the number of turns 2000, wire diameter 0.1 mm. The winding is a multilayer coil to coil. The measuring winding is connected through a rectifier to the registration device, which is used as an ammeter (milliammeter). An oscilloscope can be connected to the measuring winding, making it possible to observe distortions of rectangular voltage pulses when exposed to an external magnetic field H ₀ .

To protect the fluxgate from external influences, a protective casing is used, which is a brass tube.

To compensate for the influence of extraneous sources, an additional third winding L ₃ is provided, located on top of the main windings (not shown in Fig. 1). The diameter of the additional winding wire is 0.1 mm, the number of turns is 500.

Refer to FIG. 2. The structural diagram includes:

- a generator, in particular a pulse generator, generating rectangular pulses supplied to the excitation winding L _{1 of a} flux gate;

- a flux gate including three windings;

- rectifier;

- registration devices, for example, an ammeter or milliammeter.

Consider FIG. 3.

Compensation of the constant magnetic field of the engine in the absence of cargo, as well as extraneous permanent magnetic fields is carried out by a variable resistor R _{2 by} setting the current value measured by a milliammeter to zero. The value of the resistors R ₁ and R ₃ is selected depending on the magnitude of the supply voltage.

The rectangular pulse generator can be performed on three AND-NOT elements (for example, K561LA7) powered by a 9 volt source. In this case, it is desirable to provide the ability to control the frequency. The magnitude of the magnetic field generated by the engine, and therefore the magnitude of the mass of the load is determined by the milliammeter.

An example embodiment of the invention. A new technical result is achieved through two actions performed in the following sequence:

1. Calibration of the scale of the measuring device (milliammeter).

2. Actually measuring the mass of the cargo.

Calibration of the scale is carried out in the following sequence.

1. When the engine is running for lifting and / or moving at a certain constant speed without load, the milliammeter is taken as zero mass of the load.

2. When lifting and / or moving cargo with the same constant speed, the mass of which is known, the milliammeter reading is fixed, which will correspond to the mass of the lifted cargo.

3. For a more accurate calibration of the scale and elimination of errors, the action performed in paragraph 2 can be repeated with a different mass of cargo. The scale of a calibrated milliammeter is close to linear.

Measurement of the mass of the cargo must be made when the cargo moves in the same mode in which the calibration of the scale of the measuring device was performed.

Both when calibrating the scale and when measuring the mass, it is necessary to take into account the mass of the released part of the rope, which is the ballast component of the mass and which is unstable and depends on the height of the load. Therefore, it is necessary to use a rope position sensor. Knowing the linear mass of the rope, a fairly accurate account of the influence of the mass of the rope depending on the height of the load can be made.

When using the method on lifting devices of the same type, equipped with engines of the same brand, there is no need to calibrate the scale of the measuring device for each device separately. It is enough to provide only the same installation location of the sensing element (flux gate).

The technical result. The proposed method eliminates the need for embedding sensors in electrical circuits and in the structural elements of the lifting device, does not require sophisticated technological equipment, significantly reduces the cost of measurements, while ensuring sufficient accuracy.

The proposed method allows you to install a sensitive element (flux probe) in almost any convenient place in the immediate vicinity of the engine of the lifting device and use a milliammeter as a measuring device, which ensures ease of fixing the measurement results. The method is easy to use.

A device that implements the method is compact, does not contain expensive elements and does not require careful maintenance. Preparation of the device for operation consists in taring the scale of the measuring device (milliammeter) in units of mass.

Application of the method showed that the readings of the measuring device are practically independent of the degree of possible load swing. Therefore, no additional measures are required to prevent the load from swaying when measuring mass. It is enough to provide the same engine operation mode as when calibrating the scale of the measuring device.

The claimed technical effect is achieved when using DC motors without pulse speed control, which is a limiting factor in the application of this method.

Information sources

1. Afanasyev Yu.V., Flux Probes. - L.: Energy, 1969. - 168 p.

2. Afanasyev Yu.V., Studentsov NV, Shchelkin AP, Magnetometric converters, devices, installations. - L .: Energy, 1972.- 272 p.

3. Milovzorov V.P. Electromagnetic automation devices. - M.: "Higher School", 1974. - 414 p.

4. Borovskikh Yu.I., Busygin B.P. Electric equipment of hoisting-and-transport machines. - M.: Mechanical Engineering, 1979. - 184 p.

5. Alexandrov M.P. Lifting machines: Textbook for high schools. - M.: Publishing House of MSTU. N.E. Bauman - High School, 2000 .-- 552 p.

6. Dobronravov S.S., Dronov V.G., Construction vehicles and the basics of automation: Textbook. for builds, universities. - M .: Higher. Shk., 2001 .-- 575 p.: Ill.

Claims (1)

A method for estimating the mass of a load being lifted and / or moved by a lifting and transport device, characterized in that the magnetic field proportional to the mass of the load, which is generated by the DC traction motor, is contactlessly measured using a measuring device, and the scale of the measuring device is calibrated in units of mass.

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