RU169281U1 - LOAD LOAD LIMITER - Google Patents

Abstract

The utility model relates to hoisting and transport machinery and can be used in crane protection systems for loading and unloading, construction and installation works in industry and construction. The capacity limiter of the jib crane contains two cable force sensors, an output unit connected at the input to the computing device. The load limiter is equipped with a working algorithm block, both cable force sensors are connected with a working algorithm block, which is connected to a computing device at the output. In this case, the first cable force sensor is connected to the fixed branch of the cargo cable, the second cable force sensor is connected to the movable branch of the cargo cable. The load limiter increases the safety of the jib crane due to the fact that the design features of the crane do not affect the accuracy of measuring the mass of the cargo, provides direct measurement of the mass of the cargo. In addition, the use of a load limiter can improve the accuracy of measuring the mass of cargo at long-range boom flights. 7 c.p. f-ly, 2 ill.

Description

The utility model relates to hoisting and transport machinery and can be used in the protection system of a jib crane, self-propelled jib crane from overloads.

A safety device for a crane is known (patent for the invention of the Russian Federation No. 2307061, priority 12/26/2005), containing an information control unit coupled to an output device, sensors for determining the spatial position of crane elements and nodes using indirect parameters obtained using pressure sensors installed in the rod and piston cavities of the boom lifting hydraulic cylinder or cable force transducer located on the movable branch of the cargo rope of the boom root section. This system does not allow to solve the problem of safe operation of the crane at maximum departures, without ensuring a guaranteed shutdown of the crane mechanisms when lifting a load exceeding the rated load capacity for this departure by more than 10%. This is because for a system with pressure sensors, the generated signal depends not only on the change in the mass of the load on the hook, but also on friction losses in the seals of the hydraulic cylinders. For a system with a cable force sensor, the required accuracy is not provided when measuring the mass of a load. This is because the amount of friction in the chain hoist non-linearly depends on the number of branches of the chain hoist, its workmanship and the force acting on it.

The presence of friction losses for large boom extensions makes serious errors in the protection system of a crane, significantly reducing the safety of using the crane, its working weight and height characteristics and consumer attractiveness.

The technical result of the utility model is to increase the safety of the jib crane due to the fact that the design features of the crane (friction in the seals of the hydraulic cylinders and in the pulley block) do not affect the accuracy of measuring the mass of the load, direct measurement of the mass of the load is provided. Another technical result is to increase the accuracy of measuring the mass of cargo on long-range boom flights.

The technical result is achieved in that the load limiter of a jib crane containing a cable force sensor, an output unit connected at the input to a computing device, according to a technical solution, the load limiter is equipped with a second cable force sensor, an algorithm algorithm unit, both cable force sensors are connected to the operation algorithm block , which at the output is connected with a computing device, while the first cable force sensor is connected to the fixed branch of the cargo rope, the second cable the force sensor is connected to the movable branch of the cargo rope. The first cable force sensor is pivotally mounted on the head of the crane boom, made in the form of an S-shaped strain gauge type tensile-compression stainless steel or steel of increased hardness. The second cable force sensor is installed on the root section of the crane jib, made in the form of a device consisting of two support rollers and a strain gauge block with a high accuracy class. The operation algorithm block is made in the form of an electronic device for converting signals from two cable sensors into a signal equivalent to the sum of these signals without the influence of friction in the chain block. A microcontroller is used as a computing device for processing input signals and generating output signals. The output unit contains power switches made in the form of electromagnetic relays or power integrated circuits.

The utility model is illustrated by drawings, where

in FIG. 1 shows a structural diagram of a load limiter of a jib crane;

in FIG. 2 shows the location of the cable force sensors on the jib crane.

The capacity limiter of the jib crane contains the first cable force sensor 1 mounted pivotally in the head 2 of the boom 3 or jib and connected to the fixed branch 5 of the cargo cable 6. The output of the cable force sensor 1 is connected to the operation algorithm block (BAR) 7. The second cable force sensor 8 located on the root section 9 of boom 3, connected to the movable branch 10 of the cargo rope 6 of the symmetrical opposite stationary branch 5 of the cargo rope 6. The output of the second cable force sensor 8 is connected to the block of the operating algorithm 7. B R 7 - electronic device for comparing and converting the signals from the two sensors in rope signal equivalent to the sum of these signals without influence of friction in the pulley. The output of the BAR 7 is connected to a computing device 11 connected to the output unit 12. The output unit 12 includes power switches made in the form of electromagnetic relays or power integrated circuits connected to the actuator 13.

As an actuator 13, for example, a discrete electromagnetic valve (s), which is an integral part of a hydraulic (mechanical) crane control system, or a control controller, which is an integral part of an electro-hydraulic proportional control system of a jib crane 4, can be used.

The cable force sensor 1 can be made in the form of an S-shaped strain gauge type tensile-compression stainless steel or high hardness steel. For attaching the sensor to the fixed branch of the rope on one side and for attaching the sensor to the head of the boom on the other side, an insertion unit is provided to prevent the influence of lateral forces.

The cable force sensor 8 is made in the form of a device consisting of two support rollers and a strain gauge converter unit with a high accuracy class, for measuring the tension force in the movable branch 10 of the cargo rope 6.

As the computing device 11 for processing input signals and generating output signals, a microcontroller is used.

The operation of the crane is as follows. Operator commands to control the crane mechanisms come from controls (joysticks) that simulate the operation of spools using electromagnetic valves for electro-hydraulic proportional control systems. When lifting and lowering the load, the signal from the first cable force sensor 1 and the signal from the second cable force sensor 8 are supplied to the BAR 7. In the BAR 7, the signals from two cable sensors are compared and summed. The value of the weight of the cargo is judged by the value at the output of the BAR 7. If the nominal value of the carrying capacity is exceeded by 10%, a prohibition command is generated at the output of the computing device 11 — blocking the crane operation to raise the hook with the load, aimed at increasing the load moment. The signal from the output unit 12 breaks the circuit of a discrete electromagnetic valve (for hydraulic control of the crane) that controls the mechanical operations of the crane (turning, telescoping the boom, raising and lowering the boom, raising and lowering the hook), or enters the controller for controlling crane operations (for electro-hydraulic systems) .

If there is one cable sensor in the fixed branch 5 of the cargo rope 6, the low accuracy of measuring the mass of the cargo is explained by the fact that the total force brought to this sensor consists of two parts: the force created by the load weight F _1gr and the force required to overcome the friction in polyspast blocks F _1pol . When lowering the load, the friction force in the chain hoist is added to the force created by the weight of the cargo, and when lifting the load, the force is subtracted. Full signal when lowering is _1opusk F = F + F _{1pol 1g,} during lifting with full signal F sensor _{1pod 1g} = F - F _1pol. The amount of friction in the chain hoist F _{pol1 is} not strictly normalized. Depending on the quality of manufacture, the number of chain hoist branches, degradation processes in the chain hoist (aging), the force acting on the chain hoist, the friction value in the chain hoist can vary significantly, including over time, which does not allow to implement accurate measuring systems of this kind in devices .

If there is one cable sensor on the movable branch 10 of the cargo rope 6, the low measurement accuracy is due to the same disadvantages as for the above case. When lowering the load, the friction force in the chain hoist is deducted F _2down = F _2gr -F _2pole , and when lifting the friction force in the chain hoist is added F _2po = F _2gr + F _2pole . In this embodiment, friction in the pulley block also affects the accuracy of the measurement result.

High measurement accuracy is achieved by using cable sensors together. Both in statics and dynamics, when working with the same load weight, the output signals from both sensors are aligned and summed, eliminating the influence of friction in the chain block. After the adjustment signals in the bar 7: F = F _{2g 1g,} P = F _{1pol 2pol.} When lifting the overall output signal after BAR 7 is: F = F _{Σpod 1pod 2The} + F = (F -F _{1pol 1g)} + (F + F _{2pol 1g)} = F + F _{2g 1g} = 2F _c, i.e., at the output of BAR 7 we get a signal proportional to twice the weight of the cargo without the influence of friction in the chain block. By lowering the overall output signal after BAR 7 is: F = F _{Σopusk 1opusk 2opusk} + F = (F + F _{1pol 1g)} + (F _{2g 2pol} -F) = F + F _{2g 1g} = 2F _c.

where F _1gr - the force created by the weight of the cargo for the cable sensor 1 connected to the fixed branch 5 of the cargo rope 6;

F _2gr - the force created by the weight of the cargo for the cable sensor 8 connected to the movable branch 10 of the cargo rope 6;

F 1 _floor - the force required to overcome the friction in the block of the chain block for the cable sensor 1 connected to the fixed branch 5 of the cargo rope 6;

F _2floor - the force required to overcome the friction in the block of the chain block for the cable sensor 8 connected to the movable branch 10 of the cargo rope 6;

F _1pod - lifting force taking into account the friction in the block of the chain block for the cable sensor 1 connected to the fixed branch 5 of the cargo rope 6;

F _2pod - lifting force taking into account friction in the block of the chain block for the cable sensor 8 connected to the movable branch 10 of the cargo rope 6;

F _{1 lowering} - the force when lowering, taking into account friction in the block of the chain block for the cable sensor 1 connected to the fixed branch 5 of the cargo rope 6;

F _2opusk - the force when lowering, taking into account friction in the block of the chain block for the cable sensor 8 connected to the movable branch 10 of the cargo rope 6;

F _Σpod - total effort when lifting without the influence of friction;

F _{Σ lowering} - the total force when lowering without the influence of friction.

The crane load limiter provides direct load measurement, increases the safety of the crane, improves the accuracy of measuring the mass of cargo at long boom missions, thereby eliminating the significant disadvantages of the prototype.

The proposed crane capacity limiter can be used in all types of jib cranes, including self-propelled jib cranes, in industry and construction.

Claims (8)

1. The load capacity limiter of the jib crane, comprising a cable force sensor, an output unit connected at the input to a computing device, characterized in that it is equipped with a second cable force sensor, an operation algorithm unit, both cable force sensors are connected to the operation algorithm unit, which is output connected to a computing device, while the first cable force sensor is connected to the fixed branch of the cargo rope, the second cable force sensor is connected to the movable branch of the cargo cable. 2. The load capacity limiter of the jib crane according to claim 1, characterized in that the first cable force sensor is pivotally mounted on the head of the crane jib. 3. The capacity limiter of the jib crane according to claim 1, characterized in that the first cable force sensor is made in the form of an S-shaped strain gauge type tensile-compression stainless steel or steel of increased hardness. 4. The load capacity limiter of the jib crane according to claim 1, characterized in that the second cable force sensor is installed on the root section of the crane jib. 5. The load capacity limiter of the jib crane according to claim 1, characterized in that the second cable force sensor is made in the form of a device consisting of two support rollers and a strain gauge block with a high accuracy class. 6. The capacity limiter of the jib crane according to claim 1, characterized in that the operation algorithm block is made in the form of an electronic device for converting signals from two cable sensors into a signal equivalent to the sum of these signals without the influence of friction in the chain block. 7. The load capacity limiter of the jib crane according to claim 1, characterized in that a microcontroller is used as a computing device. 8. The capacity limiter of the jib crane according to claim 1, characterized in that the output unit includes power switches made in the form of electromagnetic relays or power integrated circuits.

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