SU66968A1 - Device for automatic braking of an electric crane - Google Patents

Description

The length of the bridge, along which the overload trolley of the metallurgical and port overload is moving, reaches 250 m. With such a bridge length, a cart weighing 100-140 tons reaches a speed of up to 400 m / min. Usually, in such mechanisms, the equipment and control of the direct current motor are concentrated on the carriage itself, and the power is supplied from the support using a trolley line.

Issues of great interest for the operation of the trolley mechanism are electric braking when relieving voltage from power trolley wires and automatically reducing speed from a given point on the path of movement.

The first task is of exceptional importance, since in operation the mechanical brakes are worn and misaligned, with the result that their action is unreliable and insufficient. A number of cases of accidents and complete breakdown of dead-end devices as a result of misalignment of mechanical brakes in the absence of electrical braking (under pressure) were noted.

There is a need for reliable electric braking when the voltage is suddenly removed from the power trolley wires. However, in the literature, both domestic and foreign, there is no information about the solution of this problem on conventional equipment, since the braking of the mechanism of movement is associated with a reverse in two directions with de-energized equipment.

On the second question, about speed limits from a given waypoint for high-speed mechanisms, there is also no satisfactory solution, since the mechanical switches used for this purpose break at trolley speeds exceeding 200 m / min, which, I understand; forces to reduce the speed of movement and, consequently, the performance of the whole mechanism. There is a need to reduce the speed of movement from a given point of the path by an automagical effect on the control circuit, while not resorting to equipment acting on the principle of a lever switch.

To solve these problems, a device is proposed in which, according to the invention, insulated brake sections of an additional trolley wire are used, connected to the trolley wires at the ends of the crane's driving path; On this additional trolley wire, the auxiliary current collector slides through the motor excitation serial winding to the midpoint of the braking resistance and to the common contact point of the reversing contactors using a normally closed contact of the brake contactor. When the current collectors enter the brake section, in the absence of voltage in the trolley line, the brake contactors automatically switch on the measurand and serial winding of the motor excitation to the braking resistance.

In the drawing (Fig. 1 and 2) shows the proposed device in two versions, in Fig. 1. Figures 3 and 4 give the corresponding contact controller switching circuits.

As can be seen from FIG. 1 of the drawing, in the presence of voltage in the network, the operation of the mechanism is possible only after switching on the negative IT contactors, 2T: 3T, disconnecting the connections necessary for braking during the voltage release.

The trolley is operated in the usual way, for which the control circuit is presented in an elementary form as an illustration.

When relieving the voltage in the middle section of the bridge, there is no urgent need for electric braking, since under the action of even misaligned brakes the carriage is not at risk of a deadlock. Odiako, if the voltage relieves when the cart is located near a dead end (15–20 m), then an accident is inevitable. The proposed device provides for the automatic occurrence of electric braking from a given point of the path (determined by calculation) by relieving the voltage and thus ensures the safety of work, preventing possible accidents. If, for example, when moving in “forward” voltage, the voltage is removed without reaching the partitioning of the ground wire to the junction of the trolley wire / I, then it is obvious that braking will start after the auxiliary current collector hits the left portion of this wire connected to the trolley wire //, and thus communicates with the current collector 3. This forms a circuit consisting of a drive motor core D, ground by the BS resistance, and the serial winding CO is connected parallel to the BA resistance, and since its resistance is 1-2% Kngm, it is practically possible to say that a circuit is formed from the core, the serial winding CO and the resistance ac connected in series, and in the serial winding the direction of the current has not changed, i.e. there is a generator mode.

It is easy to see how, when moving in the "backward" direction, a generator circuit is formed on the passage of the sectional SYA, when the current collector 1 is connected to the current collector 2 through an additional wire section, connecting-. Trolley wire. Thus, the combination of an additional trolley wire with the main ones replaces two contactors, normally open, the inclusion of which is not connected with the voltage, and thus makes it possible to solve the problem posed. It should be noted that the presence of negative contactors Sh. B and ShN in the indicated connection is indispensable. In conventional bypass circuits, a single contactor is installed, but in this device the use of two contactors does not increase the total number of power contactors, since the resistances a6 and ac can be used as the first step

accelerate, thereby eliminating the first accelerator contactor. However, other contactor switching sequences are possible. In use, the BS resistance is only when braking at the zero position of the controller and when the voltage is removed, the total number of negative contactors and the circuit of their connection remain unchanged. Switching on the mechanism after voltage recovery is performed by pressing buttons K. and K1 with the power switch disconnected.

The introduction of an additional trolley wire, double-partitioned, the opposite ends of which are connected to different poles of the power trolley wires, allows to obtain a reliable speed limit, the apparatus of which does not depend on the speed of movement.

Two shunt time relays OSV and OSI (with a delay time of 0.2-0.5 sec.), Connected in series, receive power from the power trolley wires. The common point of both relays is connected to the current collector /, which slides over the additional trolley wire. In the middle section of the bridge, both relays are turned on, allowing movement in both directions. When passing a section, the relays of this direction are shunted by a short and are turned off, affecting the speed limiters accordingly, similarly to the lever switches. At the same time, the reverse direction relay is turned on and allows movement in the reverse direction at full speed. If you want to get a second speed limit or control the first, it is enough to connect a relay parallel to the WWS and UN relay with a time delay of 4-5 seconds.

FIG. Figure 2 of the drawing shows a second version of the device that resolves the same tasks and provides greater reliability and the possibility of service braking with the participation of a series excitation. In this device, the sliding contact is constantly monitored, which is achieved by installing a second additional trolley wire IV and a slightly different combination of speed limit. As can be easily seen from FIG. 2, by setting the controller to zero position, the creation of a brake circuit in the areas of speed limits is achieved, regardless of whether or not there is voltage in the network.

The introduction of additional current collectors 5 and 6 is associated with the requirement to control the sliding contact and the presence of current collectors on the trolley wire. Control of these elements in combination with service braking significantly increases the reliability of the system compared to the first option.

The somewhat modified speed limiting system associated with the introduction of an additional second trolley wire is fundamentally different only in the control of the sliding contact, and the introduction of a speed limiting serial relay eliminates arbitrary disconnections from various kinds of leakage bypass relays.

Subject invention

Claims (3)

1. Device for automatic braking of an electric crane driven by a direct current motor fed from a trolley line and braked by short-circuiting it on braking resistance, distinguished by the fact that insulated brake sections of an additional trolley wire are connected to the trolley wires at the ends of the crane movement path the auxiliary current collector slides through the motor excitation serial to the midpoint of the braking resistance and to the common point to Reversing contactors are operated using a normally closed contact of a brake contactor, so that if there is no voltage in the trolley line, the brake contactors automatically switch on the brake resistance when the current collectors enter the brake section. 2. The form of the device pop. 1, characterized by the use of two series-connected voltage relays, terminated by the ends to the main current collectors, and a common point to the auxiliary current collector so that when the current collectors switch to the braking section the corresponding of these relays was shunted and caused the contactors to turn on, including the braking resistance. 3. Modification of the device according to claim 1, characterized in that two additional trolley wires are used, the isolated (brake) sections of which are connected to different trolley wires, and two auxiliary current collectors, the adventure ones through the normally closed contacts of the brake contactors to the ends of the brake resistance, the midpoint of which is electrically connected to the common point of contact of the reversing contactors. hchksh h la xi w "ua & apuunoe mopi cajee mije tt acmunn cephuscpc sb / oT / ru rpcSoga e ofuxa ofbif u, 4fpDof, blf CofOuMumu i / 5ri iy / r5.7 JTu- cHzczczczz chfczch, cfOuMumu i / 5ri iy / r5.7 mint. s / l9 Hogs. NOSmi cgenar.-i (: t4.m / HKttjj j FIG. 3 noMat go f of mf all & nd FIG 2 FIG. four lioMoitJ o- f1o / fnapolep noijSa) nomaiJujt lywc / o #L «№. | 1 ifosfloffuvetftfou. yfV I cffOfMcTJ II JVfiitaiCiettfeaSflOvl I ettja / ce Moff utrSapuu niSefgparpozemie, f involving eepufafi ooi ornxu (