SU1754612A1 - Device for estimating characteristics mine hoist travel in emergency braking - Google Patents

Abstract

The device contains one force sensor 1 in brake brakes, a brake activation unit 2, a switch 3, a signal level indicator 4, a free coasting acceleration unit, a set b of initial deceleration rate settings, integrators 7, 8, adders 9, 10, a scaling unit. 1-11-9-7-10-8-3- 4; 2-7; 2-8; 5-9; 5-3; 6-10; 6-3. 2 Il.

Description

fig 2

The invention relates to elevating systems and may find application in setting up protection against overspeed.

According to current safety regulations, each lifting installation must be provided with protection against overspeed. Their purpose is to transfer the driving mode to the emergency braking mode, if for some reason the current speed value becomes higher than the speed determined by the protective diagram. The protective speed chart (Fig. 1, curve 1) - the dependence of the speed V on the position of the lifting vessel in the barrel h, which is formed by means of protection, should be arranged so that the lifting vessels can be stopped during emergency braking in the working area of the movement or in the areas of regulated reloading. For this, the protections must be configured so that the protective diagram is located below the critical diagram. The critical velocity diagram (Fig. 1, curve 2) is the dependence of the stopping distance hT on the initial braking speed V0 for the most dangerous mode — the descent of the maximum calculated load. In this case, the stopping distance is maximum.

All other things being equal (the known reduced mass of the lifting unit gpr., The maximum calculated mass of the lowered load, which determines the static difference of forces in the raised and lowered branches of the lifting unit FCT, initial braking speed Vo), the stopping distance is determined by the law of variation of the braking force F, which depends on the setting of the brake actuator and the friction coefficient of the brake pair of brake pads - brake rim ftp.

Various devices for determining the critical velocity diagram are known.

One of them implements the method, namely, that the lifting vessel is loaded with the calculated load, accelerates in the load descent direction to a certain initial deceleration rate V0, an emergency brake is applied and the braking distance hT is measured. Such measurements are made for several (5-6) different values of the rate of Vo, including the maximum.

Such a device has a number of drawbacks, since it must contain a device for measuring the stopping distance, and it implies repeated repetition of measurements in the most dangerous mode of operation — emergency braking during the descent of the maximum calculated load.

Closest to the invention is a device consisting of a braking force sensor, a braking unit, a time pulse generator, a braking force setting unit, a comparator unit, a switch, a signal strength indicator, and a pulse counter.

To determine the critical velocity diagram using this device, there is no need to apply the brake when the maximum calculated load is lowered at high speeds, and it is sufficient to remove the oscillogram of the change in braking force (force in the FT brake actuator) on the fixed lifting machine. Using the obtained waveform, specifying the values of mnp, FCT and fTp, calculate the values of Ht for various V0 using the well-known graphic techniques.

The disadvantage of such a device is also a rather large labor intensity.

and low accuracy of determining the PT, due to the need for manual graphic processing of oscillograms and the variability of the coefficient of friction fTp in the process of operation of the lifting installation.

The purpose of the invention is to reduce the labor intensity and the time for setting up works.

The goal is achieved by the fact that a device containing a force sensor in brake brakes, a brake actuation unit, a switch, the output of which is connected to the input of a signal level indicator, is additionally equipped with free coast down acceleration settings and an initial braking speed, two integrators and two adders, a scaling unit wherein the output of the force sensor in the brake brakes is connected to the first input of the first adder via the scaler,

the second input of which is connected to the output of the block of acceleration settings of free coasting and the first input of the switch, and the output - to the input of the first integrator, the control input of which is connected to the output of the block

switching on the brake and the control input of the second integrator, and the output to the first input of the second adder, the second input of which is connected to the output of the block of settings for the initial deceleration rate and the second

the input of the switch, and the output with the input of the second integrator, the output of which is connected to the third input of the switch.

Figure 1 shows the protective and critical diagrams of the speed of the device; figure 2 - functional diagram of the device

The device consists of a force sensor 1 in brakes DUTT, a brake actuation unit 2, a switch 3, a signal level indicator 4, a unit 5 of the free coasting acceleration settings, a unit 6 of the initial braking speed settings, integrators 7 and 8, adders 9 and 10, scaling unit 11, with the output of sensor 1 in brake brakes through scaling unit 11 connected to the first input of the first adder 9, the output of block 5 of the acceleration settings for freedoms (the left run is connected to the second input of the first adder

9 and the first input of the switch 3. The output of the first adder 9 is connected to the input of the first integrator 7, the output of which is connected to the first input of the second adder 10, the output of the block b of the initial deceleration rate settings b is connected to the second input of the second adder 10 and the second input of the switch 3, the output of the second adder

10 is connected to the input of the second integrator 8, the output of which is connected to the third input of the switch 3, and the output of the brake actuation unit 2 is connected to the control inputs of the first 7 and second 8 integrators.

The force sensor 1 in the brake thrust is a transducer of displacement, deformation (strain gauge, inductive, differential-transformer, etc.). A button, a toggle switch, and a relay are used as the brake actuation unit 2. The switch 3 is a mechanical or electronic multi-position switch. The signal level indicator 4 is a digital voltmeter. As a block of 5 settings for acceleration of free coasting, block 6 of settings for initial speed of braking, block 11 of scaling, adjustable voltage dividers (potentiometers) are used Totalizers 9, 10 and integrators 7, 8 are made on an operational amplifier x with relay control elements and output voltage limiting elements 4, 5, 6, 7

The device implements the following functional dependency.

Fri (a0 + Yes) OR - dt, (1) oo

where hT - the value of the path traveled by the hoist during emergency braking;

a0-acceleration (deceleration) of free run

a0

GTS

GPPR

(2)

Yes - increment of deceleration under the action of the braking force F applied to the lifting installation,

ten

Yes

GPPR

 at

i is the gear ratio of the part of the brake actuator between the belts, in which the FT force is measured, and the brake pads;

rj- efficiency of the same part of the brake drive;

RT, RH - respectively, the radius of the brake rim and drum winding (tractionist pulley).

To determine hT, using the proposed device, in accordance with the expression (1), connect the first input of the switch 3 and, according to the indicator readings

4 signal levels are set at the output of block 5 of acceleration settings of the free coasting signal corresponding to a0 determined by expression (2) - Scaling block 11 sets the proportionality factor Yes and FT determined by expression (3), connect the second input of switch 3 and read m indicator 4 level signal set at the output of the set b of the initial settings

deceleration rate signal corresponding to one of the specified values of V0. Release the lift unit and using the brake actuation unit 2, the brake is applied and the integrators 7, 8 are switched to the integration mode. In this case, at the output of the first adder 9, the law of variation of the acceleration a0 + Yes will form, at the output of the second adder 10 - the law of change of velocity V, and at the output

the second integrator 8 is the law of change in stopping distance hT. When the signal at the output of the second adder 10 decreases to zero, the second integrator 8 stops integrating, and the signal at its output corresponds to

the stopping distance hT, the value of which is determined by the indications of the signal strength indicator 4, which is currently connected to the second integrator 8 via switch 3. Such measurements on a standing lifting machine are made for different V0 values and a critical speed diagram is drawn from them.

When using the proposed device, the laboriousness and time to determine

movement parameters of mine hoists in the period of emergency (safety) braking are reduced by 6-8 times.

Claims (1)

The invention of the device for determining the parameters of movement of mine hoisting machines during emergency braking, contains a force sensor in the brake brakes, a brake actuation unit, a switch, the output of which is connected to the input of the signal level indicator, characterized in that in order to reduce the labor intensity and time for commissioning work , it is equipped with blocks of settings for initial speed of braking and acceleration of free coasting, a scaling unit, two sum five tori and two integrators, with the output of the force sensor in the brake thrust through the scaler connected to the first input of the first adder, the second input of which is connected to the output of the free overrun acceleration setting unit and the first input of the switch, the output to the input of the first integrator which is connected to the outputs of the brake actuation unit and the control input of the second integrator, and the output to the first input of the second adder, the second input of which is connected to the output of the initial braking rate setting unit and the second input switch and an output - to an input of the second integrator whose output is connected to the third input of the switch. FIG. one