RU2298519C2 - Electric drive of load-lifting crane slewing mechanism - Google Patents

Abstract

FIELD: mechanical engineering; load-handling facilities.

SUBSTANCE: invention relates to multimotor electric drives of load-lifting machines. Proposed electric drive contains induction motors with phase wound rotors, of brake hydraulic pusher, master controller with control circuits connected with supply line. Connected to the latter is also electric drive control unit with clockwise and counter-clockwise rotation contactors, speed step change-over contactors, acceleration contactors, time relay, clockwise and counter-clockwise rotation memory relays and also circuit consisting of speed control pickup and rotation frequency relay. Stator windings of electric motors with phase-wound rotors are interconnected by like leads and are connected to system according to plugging scheme. Maximum current relay is connected to one of phases of stator winding of each motor with phase-wound rotor. Each motor with phase-wound rotor is furnished with unit of multistep resistors some leads of each of which being connected with corresponding phase leads of rotor winding of electric motor, and second leads of resistors are connected into star through semistors of switch. Switch control unit includes to bridge rectifiers whose inputs are connected to outputs of semistor switches, accordingly, and are shunted by contacts to prevent cutting-in of acceleration contactors at plugging of induction motors in period of time corresponding to reduction of speed to minimum value. Inductive sensor of drive brake pulley rotation speed control is mechanically coupled with shaft of one electric motors with phase-wound rotor and electrically connected with supply line of master controller.

EFFECT: reduced dynamic loads, wear and power consumption.

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Description

The invention relates to multi-engine electric drives of hoisting machines, in particular to electric drives of turning mechanisms of the rotary parts of hoisting cranes, mainly tower cranes.

In practice, in existing electric drives for turning cranes of tower cranes, asynchronous motors with a phase rotor are widely used. To control the rotation speed of the rotary part of the crane, resistors are introduced into the rotor circuit of the drive motor. To increase the speed of rotation or to accelerate the motor, the stages of the resistors are sequentially shorted for a certain period of time. To reduce the speed of rotation, the anti-inclusion braking mode is used, for which the phase rotation on the stator of the electric motor is changed by transferring the command device to the side opposite to the rotation of the rotor.

From the SU patent documentation, a twin-motor electric drive of a crane turning mechanism with an electric drive control device comprising two groups of contactors of direction of rotation of the motors and power contactors of the mechanical brakes of the motors during their rotation, the windings of which are connected to the power source through the corresponding contacts of the first command device, is known, the device being equipped with a second command device made with make and break contacts. The control device comprises a time relay, the winding of which is connected in series with the opening contact of the second command device, and a control contactor, the winding of which is connected in series with the closing contact of the time relay and the closing contact of the second command device, the closing contacts of the control contactor are connected in series with the windings of the mechanical brake power contactors, the winding of the first the contactor of the direction of the first group and the winding of the second contactor of the direction of the second group. The first command device has a contact of its position, through which the contacts of the control contactor and the second command device are connected to a power source [1].

From the GB patent documentation, a twin-engine AC drive of a machine is known, comprising asynchronous motors connected to separate drives that are connected for synchronous operation. When the drive is operating, voltage is applied to the capacitor when the main speed controller moves to the first straight position, while the brakes are turned off, and the capacitor changes the single-phase power supply of the stator winding to three-phase, and the contactor connects the rotor resistance to the contact rings, the rotor resistance decreases and rotation accelerates electric motor. The drive contains a relay that is triggered when a certain speed is reached, opens the corresponding contactors so that the motors rotate by inertia, and their stators are excited from only two power lines, and when the speed increases, the relay works, the rotor resistance for single-phase braking is regulated. At low speed, braking is weakened by opening the relay, and if rotation does not occur, the exciting power is used to brake by re-closing another relay at the corresponding lower speed, while the synchronous operation of the motors is supported by cross-coupling of rotors and stators and single-phase excitation stators. When a low speed is reached, one relay is activated, which includes brakes and de-energizes another relay, and reverse current braking can be provided when the controller is reversed [2].

From FR patent documentation, an electric drive for the rotation mechanism of a tower crane is known, comprising an asynchronous motor having a rotor with a winding, to which rotor current control means are connected, which allow changing the torque-speed characteristic curve, a braking device connected to the motor shaft, the moment of which increases with an increase in speed, and also connected to means for controlling the excitation current when changing the characteristics of the "moment-speed", the control body controls the rotary current of the motor atelier, a speed detector that transmits a signal to the control element, a brake brake control device, a voltage adjustment device, a pre-adjusted element acting on the adjustment device, and a speed indicator [3].

The closest technical solution in essence and the achieved effect to this invention is an electric drive with its control device for moving a crane, the device contains reversing contactors, the contacts of which are included in the power circuit of the stator winding of an asynchronous electric motor, in the power circuit of the rotor winding of which are included ballast resistors and a thyristor switch, the control input of which is connected through a threshold element and a pulse distributor to the rotor winding circuit, to a mandocontroller, whose contacts are included in the chain of coils of reversing contactors, brake contactors and acceleration contactors, and a speed sensor, the device is equipped with a directional memory relay, coils of which are connected in series with the corresponding contacts of the command controller and reversing contactors, with an additional contactor, in whose winding circuit a closing contact is included the brake contactor, and the brake pedal, the opening contact of which is included in the power circuit of the mentioned contactor windings, and the closing - in the power supply circuit of the coils of reversing contactors through the corresponding closing contacts of the memory relay, and one closing contact of the brake contactor is included in the power supply circuit of the coils of the memory relay, coils of reversing contactors through the said closing contact of the brake pedal and in the power supply circuit of the coil of the brake contactor through the opening contact of the speed sensor included in one phase of the thyristor regulator, in the circuit of another phase of which one closing contact of the additional contactor is connected, the second closing contact of the cat It is included in the control circuit of the threshold element [4].

In practice, during operation of known electric drives, dynamic moments arise. This is due to the inhibition of the turning mechanism electric motor due to the fact that the resistance included in the rotor circuit is selected on the basis of providing the rated braking torque at the rated speed, while during operation of the drive the command device is set to the first position, and when transferring the command device to other positions, the acceleration contactors and the steps of the resistors in the rotor are shorted, which leads to large dynamic shock loads and breakdowns of mechanisms.

In order to eliminate these drawbacks of existing designs of electric drives, an electric drive is proposed having means of prohibiting the inclusion of acceleration contactors when braking by anti-inclusion in such a period of time when the speed decreases to a minimum value.

Solved and achievable technical objective of the present invention is to reduce dynamic loads in the drive, its wear, energy consumption and increase safety.

The stated technical problem is solved in that the electric drive of the crane turning mechanism comprises asynchronous electric motors with phase rotors, hydraulic hydropushers of brakes, a command controller with control circuits connected to a power line to which an electric drive control unit is connected having right and left rotation contactors, stage switching contactors speeds, acceleration contactors, time relays, right and left rotation memory relays, as well as a circuit composed of a control sensor I have a speed and a speed relay, moreover, the stator windings of electric motors with phase rotors with their same outputs are connected to each other and connected to the network according to an opposition circuit, one of the phases of the stator winding of each electric motor with a phase rotor includes a maximum current relay, each electric motor with a phase rotor is equipped with a block of multi-stage resistors, one of the terminals of each of which is connected to the corresponding phase terminals of the motor winding of the rotor, the second terminals of the resistors are connected to I drive through the triacs of the switch, the control unit of the switches, composed of two bridge rectifiers, the inputs of which are shunted by the contacts and connected to the outputs of the triac switches, respectively, an inductive sensor for controlling the rotation speed of the brake pulley of the drive, mechanically connected to the shaft of one of the electric motors with a phase rotor and electrically connected to power line command controller.

Figure 1 shows the electric drive of the rotation mechanism of the crane with its control device, figure 2 - the control unit of the electric drive and the control unit of the electric drive, figure 3 - table of inclusion of the electric drive with conditionally shown drive elements on it.

The control device contains asynchronous electric motors 1 (Fig. 1) electrically interconnected with phase rotors, one of which is connected with an inductive sensor 2 for controlling the speed of rotation of the motor shaft, block 3 of resistors 4, triacs 5 of two AC switches 6, rectifier bridges 7 on diodes, a comparison unit 8, a resistor or potentiometer 9 of the comparison unit 8, while the comparison unit 8 is connected to the switches 6 through rectifier bridges 7. The resistor unit 3 has contactors 10.

The electric drive has a maximum current relay 11, each of which is included in the power circuit of the corresponding electric motor 1. Electric motors 1 through contactors 12 are connected to electric motors 13 of the drive of the hydraulic pushers 14 of the brakes of the rotation mechanism.

Figure 2 shows the controller 15, connected by connectors 16 to the power line 17 of the control unit 18. The controller 15 and the brake pedal 19 are part of the electric drive control unit 20, which is shown in dotted lines in figure 2 on its left side.

Shown by other dashed lines, on the right side of FIG. 2, the control unit 18 contains contactor coils 21, a control resistor, in particular a potentiometer 22, a minimum speed sensor 2 setpoint 23, contacts 24 and similar contacts, relay 25, two memory relay coils 26 direction of rotation, one of which, the upper coil 2K11 in figure 2, is a coil of the right direction of rotation of the rotary part of the crane, and the second coil 2K21 is a coil of the left direction of the rotary part of the crane. The control unit 18 also contains a time delay contact 27, normally closed contacts 28 and 29 and other similar contacts, a circuit 30 with a speed control sensor 2 included therein, a brake contactor 31 conventionally shown in the table of FIG. 3, coils 32 and 33 contactors (figure 2) and other similar coils that do not have digital positions in figure 2. The coils 32 and 33 and the coils located between them or all of the coils 2KM4-2KM9 of the contactors shown in FIG. 2 are coils of acceleration contactors. Corresponding contactors are connected to these coils, which are shown conditionally on the table of FIG. 3 and are mentioned below.

Figure 1 also conventionally shows the brake pulleys 34 of the drive of the rotation mechanism, interacting with the brakes 35 associated with the hydraulic pushers 14, which are connected to the electric motors 13 of the electric drive. The switches 6 are connected to the resistors 4 and form a block 36 of switches, and the rectifier bridges 7 with a potentiometer 9 form a block 37 control switches, which is connected to the latter.

The control unit 18 (figure 2) is connected to the power supply line 17 of the controller. The stator windings of electric motors 1 with phase rotors of the same name leads are interconnected and through contactors 38 (figure 1) are connected to the network according to the circuit of the opposition. Said overcurrent relays 11 are included in one of the phases of the stator winding of each electric motor 1 with a phase rotor, and these relays 11 are interconnected. The resistors 4 of the electric drive 1 are connected with one of their conclusions to the corresponding phase outputs of the windings of the rotors of the electric motors 1, and the second conclusions of the resistors 4 are connected to the star through the triacs 5 of the switches 6. In the control unit 37 of the triacs 5, the inputs of two bridge rectifiers 7 are bridged by contacts 39 and connected to the outputs of the triacs switches 6, respectively. The inductive sensor 2 for controlling the rotation speed of the brake pulley of the drive is electromagnetically connected to the shaft of one of the electric motors with a phase rotor and is electrically connected to the power supply line 17 of the controller 15.

The electric drive contains contactors 40 and 41 of the right and left rotation (Fig. 3), speed switching step contactors 42, acceleration contactors 43, time relay 44 and memory relay 45 and 46, respectively, of the right and left rotation, as well as the speed relay 47. The circuit 30 (FIG. 2) consists of a potentiometer 22, a minimum speed sensor 23 and a speed relay (FIG. 3). Position 48 in figure 2 shows the power circuit of the coils of the control unit of the electric drive.

The device operates as follows.

The controller 15 is turned on (Fig. 2) to the left or right, while the coil 21 of the upper or lower contactor is turned on, depending on the direction of rotation of the crane turning part and the direction of rotation of the motor shaft selected by the operator. When one of the electric motors 1 is turned on, the brakes 35 (Fig. 1) are activated, which brake the electric drive, at the same time, the upper or lower coil 26 is powered, and the corresponding contactor 40 or 41 of the right or left direction of rotation is turned on. Upon further switching of the controller 15 to the corresponding positions “2” and “3” with delay, the acceleration contactors 43 are turned on and the motor 1 is accelerated. When the speed corresponding to the setting value 23 of the minimum speed sensor 2 is turned on, the corresponding contact is switched on and the speed relay 47 closes its contact in the corresponding circuit, installing the upper coil 26 (2K11) for self-feeding. For braking, it is necessary to move the handle of the controller 15 in the opposite direction. In this case, the corresponding power circuit opens and the coils 32 and 33 lose power, the contactors are activated and the motor 1 is braked by the opposition with the resistance fully entered into operation in the rotor circuit of this electric motor.

If the rotation speed is reduced to a value corresponding to below the value of the setting 23 of the minimum speed sensor 2, it loses the power of the relay 25 and allows the connection of coils 32 and 33 and their corresponding contactors through circuit 48.

The second option is work. When you install the handle of the controller 15 in the "left" position (figure 2), the contactor 38 direction 2KM1 (figure 1). The stator of the electric motor 1 is connected to the network, while the impedance is introduced into its rotor. The electric motor 1 starts powering the top of the circuit (figure 2) of the coil 26 of the memory relay (2K11). With a further translation of the controller handle to the left, the steps of the resistors 4 of block 3 are shorted (Fig. 1) in the rotor of the electric motor 1 and its acceleration stops. When this occurs, the power supply coils 32 and 33 of the acceleration contactors 43 through a closed contact 2K11 (figure 2) and a normally closed contact 28 (2KM2). When reaching the speed corresponding to the setpoint 23 of the sensor 2, the internal contact of the sensor 2 closes (Fig. 1) and it receives power from the relay 25 (2KV1). This relay closes its 2K11 contact in the self-pickup circuit.

To inhibit the opposition include moving the handle of the controller 15 to the opposite position (figure 2), and the position number of the translation of the handle in this case is not fundamental. The contactor coil 2KM2 is turned on, but the memory relay 46 (2K11) remains switched on through its own contact and relay contact 25 (2KV1). The memory relay 46 (2K21) cannot turn on due to the interlocking of the memory relay 45 and 46 (2K11 and 2K21). The connection of coils 32 of acceleration contactors 43 (2KM4 and 2KM7) is prevented by open contacts 2KM2 and 2K21. When the speed drops below the setpoint, the speed sensor 2 opens its built-in contact, loses power to relay 25 (2KV1) and breaks the self-pickup circuit of contact 2K11. In this case, contact 2K11 loses power and, through its normally closed contact, turns on memory relay 46 (2K21). Acceleration contactors 43 receive power through contacts 2KM1 and 2K21. In this position, the operator can set the controller 15 to the zero position to stop the motor or continue to move (rotation of the motor 1) in the opposite direction.

Information sources

1.SU 1357340 A, 12/07/1987.

2. GB 1178454 A, 04/18/1968.

3. FR 2067426 A, 09.24.1971.

4. SU 1805093 A1, 12/07/1987 (prototype).

Claims (1)

An electric drive of a crane turning mechanism, comprising asynchronous electric motors with phase rotors, hydraulic hydropushers of brakes, a command controller with control circuits connected to a power line to which an electric drive control unit is connected having right and left rotation contactors, speed step contactors, acceleration contactors, relays time, a left and right rotation memory relay, as well as a circuit composed of a speed control sensor and a speed relay, moreover, The windings of electric motors with phase rotors with their namesakes of the same name are interconnected and connected to the network according to the circuit of the circuit, the maximum current relay is included in one of the phases of the stator winding of each electric motor with a phase rotor, each electric motor with a phase rotor is equipped with a multi-stage resistor block, one terminal of each which are connected to the corresponding phase terminals of the rotor winding of the electric motor, the second terminals of the resistors are connected to the star through the triacs of the switch, the control unit switch, composed of two bridge rectifiers, the inputs of which are connected to the outputs of the triac switches, respectively, and are shunted by the contacts to ensure that accelerator contactors are not allowed to turn on when braking by asynchronous electric motors being turned on for a period of time corresponding to a reduction in speed to a minimum value, an inductive sensor for controlling the rotation speed of the drive brake pulley mechanically connected with the shaft of one of the motors with a phase rotor and electrically dinined with the power line of the controller.

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