DE299350C - - Google Patents

Description

KAISERLIGHES

PATENT OFFICE.

SS

in BADEN, Switzerland. _

controlled motors.

The previously known lowering brake circuits for controlled by brush displacement AC commutator motors are set up in such a way that the stator winding of the motor, which is provided with special taps for lifting and lowering when laying out the with the control lever connected to the brush bridge, in the lowering direction so placed on the network that the motor exerts such a large counter-torque at the moment it is switched on, that initially the greatest load that occurs is kept in suspension. This is required to prevent the load from sagging or falling when the lowering movement is initiated to prevent. While the stator winding is initially connected to the mains during lifting, the motor only then exerts a torque when the brushes are moved from the rest position, becomes the stator winding. when initiating the lowering movement so placed on the network that the Motor immediately exerts such a large counter-torque that it is the largest occurring Load keeps balance. The lowering is then done by gradually moving the brushes towards the zero position. Small, non-pulling loads or empty ones To be able to lower the hook, the brushes must lower than the zero position moved '.

This arrangement now has the disadvantage that smaller ones when initiating the lowering movement and medium loads can always be raised first and only then lowered, when the brushes are moved towards or beyond the zero position. In addition, the torque of the motor depends on the position of the brushes is dependent, after lifting larger loads when pushing back the Brushes in the rest position a sag, since the motor torque goes down, while the load torque remains in full size until the electromagnetic holding brake is reached when the rest position is reached occurs. \

These disadvantages are avoided in the counterbalance circuit described below. The same differs from the circuits explained above in that the motor for each brush position to Can be brought to a standstill so that it is no longer necessary to use the control lever or return the brushes to the zero position when lifting loads are stopped. Rather, the crane operator only moves the control lever so far against the zero position shift until the motor torque equilibrates the load torque, and on Apply the electromagnetic holding brake.

To switch on the lowering movement, it is then only necessary to activate the electromagnetic Release the holding brake and move the brushes towards the zero position. Since the Lowering movement always away from equilibrium

stood out, finds a very gentle and the lowering movement is initiated smoothly without the load sinking when switched off the lifting movement or initiation of the lowering movement can occur.

For a more detailed explanation of the circuit, refer to FIGS. 1 and 2 of the accompanying drawing referenced.

In the circuit shown in Fig. Ι

ίο is the one used to control the motor ι Control block 6 equipped with a switch located in the main circuit io, which mediates the hand trap 9 arranged on the control lever 8 is influenced. The control lever 8 is through the rods 7 and 4 and the angle lever 5 with the brush bridge 3 of the motor ι connected. To the self-excitation of the motor driven by the load 14 as possible To make it harmless, the resistor 13 is switched in front of the stator field when lowering. This is done automatically by the Rotary direction switch 15 arranged on the motor and dragged along by friction. To operate the holding brake, which is also arranged here on the motor shaft the brake release magnet 11.

The mode of operation of the circuit is now as follows:

In order to lift the load 14, the crane operator must move the control lever 8 to the right while simultaneously pulling the hand latch 9. This moves the brush bridge 3 counterclockwise and at the same time attaches the stator field 2 to the network. The current . then runs in the drawn position of the direction of rotation switch 15 from the i? pole via terminal 20 through the stator winding and via 23, 24 into the series resistor 13, from where it is via the terminals 30, 27 and the contacts 28 and 29 to the T ^- -PoI goes. In addition, a circuit is closed, which leads from terminal 20 via contact 21, the switching segment 15 and via contact 22, via the coil of the contactor 12 and via 26, 27, 28 and 29 'to Γ-Ροί. At the same time, the brake magnet 11 is connected to the mains via 19, 27, 28 and 29 and the holding brake is thus released. The motor will start moving in the lifting direction if there is an upstream resistance. As soon as this happens, however, the direction of rotation switch located on the motor shaft is taken along until the switching segment 15 rests against the stop 17. As a result, the coil of the contactor 12 is de-energized, which is why the latter drops out and thereby connects the contacts 25 and 26 to one another. The current runs from terminal 24 via 25, 26, 27, 28 and 29 directly to the Γ-Ροί, so that the resistor 13 is short-circuited.

If the load is to be stopped after it has been lifted, all you need is the Move the control lever towards the neutral position, but only up to a point at which motor torque and load torque are in equilibrium in order to let go of the hand latch 9. This will be contacts 28 and 29 are open, the motor and brake release magnet are disconnected from the mains and applied the holding brake.

In order to initiate the lowering movement, you have to pull the hand latch 9 and thereby the engine over 19, 20, 23, 24, 25, 26, 27, 28 and 29 to be reconnected to the mains. The engine is then at the moment of When switching on, exert the same torque that he developed before switching off the lifting movement, d. H. the load in the Keep levitation. By moving the control lever 8 after the zero position to is the load is lowered by reducing the engine torque more and more and thereby the Motor is driven by the load. As soon as the latter occurs, the switching segment becomes 15 of the direction of rotation switch is moved counterclockwise until it reaches stop 16 is applied and thereby the contacts 21 and 22 are bridged. As a result, that will Contactor 12 start up again and the contacts 25 and 26 open, whereby the resistor 13 again automatically in front of the stator ' winding is switched.

While in the circuit explained above, the attached to the control block and If the switch moved by the hand trap is in the main circuit, it is used for the in Fig. 2 shown switching arrangement only for opening and closing the control current. In addition to the apparatus shown in FIG. 1, a double contactor 42 is also provided here. ■■■ '..- ■

If the control lever 38 is in the drawn position of the direction of rotation switch while pulling the hand latch 39 to the right, ie in the lifting direction, the brush bridge 33 is moved counter-clockwise and at the same time a circuit is closed, which from the R-ToI via terminal 50 to the coil of the contactor 43 and from there via contact 58, lever 40 and contact 59 to the coil of the brake release magnet 41 and from there via 60 to the Γ-Ροί this bridges the contacts 56 and 57. However, this also causes the double contactor 42 to start, since the coil of the same is connected to the T-PoI from the Ä-Pole via terminal 51, contact 64, switching segment 46 and contacts 65 and 55. As a result, the stator winding 32 is connected to

voltage because the current is now from the B-pole via terminal 51 through the stator winding to terminal 52 and via resistor 44 and contacts 62, 63, 56 and 57 runs to the T-PoI. The rotor will therefore turn clockwise and so will the load raised. Here, the switching segment 46 is against the stop 48, d. H. in the dotted Rotated position and thereby the contacts 64 and 65 interrupted. The contactor 42 is thereby de-energized, which has the consequence that the contacts 54 and 55 with one another connected and the contacts 62 and 63 are interrupted. To interrupt the To avoid the motor circuit, the contactor is set up in such a way that contacts 62 and 63 are only interrupted after the contacts 54 and 55 are electrically connected to one another are.

The stator winding is now connected to the Γ pole via 53, 54, 55, 56 and 57; the resistance 44 thus short-circuited. If the load is to be stopped after lifting, move the control lever towards the zero position again until the engine torque is reached and load torque balance, and then release the hand latch 39. This will make the contactor 43 de-energizes and disconnects the motor from the mains. At the same time it falls as a result of the electricity being cut off of the brake release magnet 41 applies the holding brake and keeps the load in suspension. To initiate the lowering movement, the hand latch 39 is tightened again, thereby the The holding brake is released and the contactor 43 starts up. The stator winding will thus again via 51, 52, 53. 54- 55. 56 and 57 connected to the network.

The motor again exerts the same torque that it had before it was switched off developed during the lifting movement, so it keeps the load in suspension. By. Move the control lever towards the neutral position, the torque of the engine is gradually is reduced so that the latter is ultimately driven by the load. As soon as this case occurs, the switching segment 46 of the direction of rotation switch brought back into the extended position, whereby the contacts 64 and 65, connected to one another and the contactor 42 is made to start. The contacts 54 and 55 are consequently interrupted again and the contacts 62 and 63 with one another connected, where. to .Avoid arcing, hit the device in this way is that the interruption of 54 and 55 only takes place after 62 and 63 have been bridged is. The current going through the stator winding is thus forced to reduce the resistance 44 to flow through, causing the self-excitation of the motor driven by the load is prevented.

Around smaller, non-pulling loads or the empty hook after lifting to stop / you can bring the control lever directly into the zero position because the motor is not driven when switched on again. In such cases the Lower the control lever beyond the neutral position to the left and the load with it driven motor can be lowered.

As can be seen from the above, the movement of the control lever is always the movement of the load sympathetic, without anything special about the stator winding or the rotor winding Taps etc. would be required.

The circuit diagrams shown in FIGS. 1 and 2 naturally represent only two Examples of the counterbalance circuit according to the invention. In particular, it is e.g. without further possible to simplify the arrangement shown in Fig. 2 in such a way, that the contactor 43 is no longer available and the contacts 56 and 57 are brought into connection with the brake release magnet 41.

Claims (1)

Patent claim: Lowering brake circuit for non-self-locking hoists with brush adjustment controlled motors, characterized in that one with the control member the brush bridge connected switch (10 or 40) in each position of the Brush bridge enables the motor to be switched on and off, so that the movable Motor brushes when switching off the lifting or lowering movement can remain shifted as far as to achieve the state of equilibrium between load torque and engine torque is required is, for the purpose of restarting the motor in the respective Brush position immediately returns to the torque corresponding to the state of equilibrium to avoid sagging of the load and smooth introduction the lowering movement is enabled. 1 sheet of drawings.