FR2599015A1 - DEVICE FOR PROTECTING LIFTING MECHANISMS AGAINST OVERLOADS AND SPILLS. - Google Patents

Abstract

THE LIFTING MECHANISM PROTECTION DEVICE AGAINST OVERLOAD AND OVERLOADING CONTAINS A BLOCK1 FOR DETERMINING THE OVERLOADING OF THE LIFTING MECHANISM AND A BLOCK2 FOR CHECKING THE REAL STATE OF THE STABILITY OF THE LIFTING MECHANISM ON EACH OF EACH BRACKET , 4 RESPECTIVE OF A BLOCK5 OF CHOICE OF THE PROTECTION STRUCTURE OF THE LIFTING MECHANISM. A LIFTING MECHANISM STOP BLOCK6 IS CONNECTED TO THIS LATTER.

Description

The invention relates to handling equipment and, more particularly,

  it concerns the devices for protecting the lifting mechanisms against

overloads and overturning.

  The present invention can be used for protection against overloading and overturning of hydraulic self-propelled jib cranes

on pneumatic wheels.

  There is a device to protect

  lifting mechanisms against overloading and overturning (cf., the author's certificate from the U.S.S.R.

  N 1 101 402, Int. B 66 C 23/88, 1982) which includes a block for determining the overload of the mechanism and a block for stopping the mechanism electrically connected.

  However, the device in question is adjusted to the calculated bearing contour of the lifting mechanism, for example, of a crane (contour, the most favorable from the point of view of its configuration), and does not react to modifications. unfavorable of this contour, for example, to a subsidence of the ground under a jack and to the transformation of the rectangular support contour (calculated) into a triangular contour (real), which decreases the precision of the device and, therefore, the fia25 bility of the protection of the lifting mechanisms this

  which can lead to a breakdown situation.

  In addition, in said device, the block of

  determination of the overload of the program mechanism a load characteristic corresponding to the minimum admissible load capacity ca30 with consideration of an unfavorable wind, the angle of inclination of the platform, the resistance conditions of certain assemblies , etc. (for the calculated bearing contour) which, in most cases, causes insufficient use of the capacities of the lifting mechanism.

  The invention aims to create a device for protecting the lifting mechanisms against overloads and overturning provided with such auxiliary blocks which would make it possible to increase the precision of the device, to widen its functional capacities and to increase the reliability of the protection of the lifting mechanism. The object is achieved by the fact that a device for protecting the lifting mechanisms against overloads and overturning comprising a block for determining the overload of the lifting mechanism and a block for stopping the lifting mechanism electrically interconnected, in accordance with the invention also includes, electrically connected in series, a block for checking the real state of stability of the lifting mechanism and a block for choosing the protection system for the lifting mechanism, another input of which is electrically connected to the lifting mechanism overload determination block and the output is connected to the lifting mechanism stop block. It is advantageous to use in the protection device lifting mechanisms against overloads and overturning a logic circuit "OR" as a block of choice for the protection system of the

lifting mechanism.

  It is desirable to use in the device for protecting the lifting mechanisms against overloads and overturning a main "AND" logic circuit and an auxiliary "AND" logic circuit, certain inputs of which are respectively connected to the block for determining the overload of the lifting mechanism and on the control block of the real state of stability of the lifting mechanism and the outputs on the logic circuit "OR", an inverter whose output is connected to another input of the logic circuit "AND" 35 auxiliary and a tilt angle sensor of the

  boom of the lifting mechanism, the output of which is connected to the input of the reverser and to another input of the cir-

cooked main "AND" logic.

  The present invention provides control of

  the state of the crane's support contour, which increases the precision of the device and the reliability of the protection of the lifting mechanism.

  In addition to this, the present invention makes it possible either to carry out a successive determination of the

  overload, that is to check the real state of stability of the lifting mechanism, which widens the functional possibilities of the device.

  The invention will emerge from the subsequent description of a concrete example of its execution shown schematically in the accompanying drawings, including:

  - Figure 1 shows a block diagram of a device for protecting the lifting mechanisms against overloads and overturning, according to the invention; - Figure 2 shows a block diagram of a device for protecting the washing mechanisms 20 against overloads and overturning in accordance with Figure 1 with "AND" logic circuits, according to the invention; - Figure 3 shows an operating diagram of the device for protecting the lifting mechanisms against overloads and overturning for cranes with a rectangular bearing contour according to Figures 1 and 2, according to the invention; - Figure 4 shows an operating diagram of the device for protecting the lifting mechanisms against overloads and overturning for cranes with a triangular bearing contour

  according to Figures 1 and 2, according to the invention.

  The device for protecting the lifting mechanisms against overloading and overturning 35 comprises a block 1 (FIG. 1) for determining the

  overload of the lifting mechanism and a block 2 for checking the real state of stability of the lifting mechanism

  vage on the inputs of which are connected respectively inputs 3 and 4 of a block 5 of choice of the protection system of the lifting mechanism. A

  block 6 of the lifting mechanism is connected, 05 by its input 7, to the output of block 5.

  According to another alternative embodiment, the device for protecting the lifting mechanisms against overloading and overturning comprises a main "AND" logic circuit 2 (FIG. 2) and an auxiliary "AND" logic cir10 cooked 9. Respectively , inputs 10 and 11 of these circuits are connected to blocks 1 and 2. On other inputs 12 and 13, respectively "AND" circuits 8 and 9, are respectively connected a tilt angle transmitter 14 of the boom of the lifting mechanism, by its output 15, and an inverter 16. The input 17 of the inverter 16 is connected to the output 15 of the detector 14. On the inputs 3 and 4 of the block 5 are respectively connected

  the outputs of the "AND" circuits 8 and 9.

  FIG. 3 shows a diagram of the operation of the device for protecting

  lifting mechanisms against overloading and overturning for cranes with a rectangular contour, the mass of the load on the hook being invariable. In this figure, a rectangular support contour 18 is a predetermined load characteristic and a contour 19 reflects the actual state of stability of the crane.

  FIG. 4 shows a diagram30 me of the operation of the protection device for

  lifting mechanisms against overloads and overturning for cranes with triangular bearing contour, the mass of load on the hook being invariable.

  In this figure, a bearing contour 20 is a characteristic charac35 in predetermined load crossing the contour 19 in points 21 and 22 and forming two curves 23 and 24.

  The device for protecting the lifting mechanisms against overloads and overturning

  for the protection of self-propelled hydraulic cranes with boom on pneumatic wheels, works from 05 as follows.

  Block 1 (Fig. 1) for determining the crane overload is connected simultaneously and block 2 for checking the actual condition of the crane. Block 1 protects the crane at the distance defined by the contours 18 (Fig. 3) or 20 (Fig. 4), while Block 2 controls the actual state of stability of the crane, in other words, performs prior protection at distances determined by the contour 19

(Fig. 3, 4).

  The signals supplied by blocks 1 and 2 respectively attack the inputs 3, 4 of the logic "OR" circuit 5. The "OR" circuit 5 produces a control signal which attacks the input 7 of block 6 of stop of

the crane.

  Thus, the device operates according to the contour 19 (Fig. 3) and along the contour defined by the curve 23 (Fig. 4) of the contour 19 and by the line between the points 21 and 22 of the contour 20.

  In some cases it is useful that the signals from blocks 1 and 2 are supplied alternately.

  For large angles of inclination of the boom relative to the horizon, when the safety of the crane is determined by its robustness, the si30 gnal arrives from block 1 (Fig. 2). For small angles of inclination of the boom relative to the horizon, when the safety of the crane is defined by

  its stability, the signal comes from block 2.

  Thus, blocks 1 and 2 provide the signals in turn.

  The signal supplied by block 1 attacks input 10 of the main "AND" circuit 8. The other input i 12 of the "AND" circuit 8 is attacked by a signal from output 15 of the tilt angle sensor 14 of the crane boom. From the "AND" circuit 8, the signal comes to input 3 of the "OR" circuit 5. The cooked cir05 "OR" creates at input 7 of block 6 a signal for its operation. Simultaneously, from the output of the sensor 14, a signal arrives attacking the input.

  17 of the inverter 16 and, from there, the input 13 of the auxiliary logic "AND" 9 and "forbids" the wise passage of the signal from block 2 to the input 4 of the circuit "OR" 5 via the circuit " AND "9.

  For small angles of inclination of the arrow, the detector 14 does not provide a signal which blocks the passage of the signal from the block 1 to 15 through the "AND" circuit 8. Simultaneously, the inverter 16 creates at the input 13 of the "AND" circuit 9 a signal "authorizing" the passage of the signal from block 2 to input 4 of the "OR" circuit 5 via the circuit

  "AND" 9. The "OR" circuit 5 creates at input 7 of block 20 6 a signal for its operation.

  The present invention makes it possible to control the stability of the crane, which increases the reliability of its protection.

Claims (3)

  1. Device for protecting the lifting mechanisms against overloads and overturning comprising a block (1) for determining the overload of the lifting mechanism and a block (6) for stopping the lifting mechanism electrically connected to each other, characterized in that it includes, electrically connected in series, a block (2) for monitoring the real state of stability of the lifting mechanism and a block (5) for choosing the type of protection of the lifting mechanism, including one other input (3) is electrically connected to the block (1) for determining the overload of the lifting mechanism and the output   is connected to the block (6) for stopping the lifting mechanism.   2. Device according to claim 1, characterized in that it uses as a block of choice the protective structure of the mechanism lifting an "OR" logic circuit (5).   3. Device according to claim 2, characterized in that it comprises main (8) and auxiliary (9) "AND" logic circuits of which inputs (10 and 11) are respectively connected to the block (1) for determining the overload of the lifting mechanism and on the block (2) for controlling the real state of stability of the lifting mechanism and the outputs, on the "OR" logic circuit (5), an inverter (16) whose output is connected to another input (13) of the auxiliary "AND" logic circuit (9) and a sensor (14) of angle of inclination of the boom of the lifting mechanism, an output (15) of which is connected to an input (17) of the inverter (16) and on another input (12) of the logic circuit "AND" (8) main.