EP0733581B1 - Hoisting device with running gear, having negligible oscillation under braking - Google Patents

Abstract

The armature shaft (3) of the universal motor (2) is coupled to the input shaft (4) of the reduction gear (5) driving the wheels (7) on running rails (8). A triac (22) feeding the motor is gated by a regulator (24) responsive to a wheel speed sensor (27) and a microprocessor (28) commanded by switches (34). The control extends to a driver (17) of another triac (16) or relay activating an electromagnetic disc brake (13,11). While forward speed is being reduced the brake is released so that the crane is slowed only by its internal friction and running rail resistance.

Description

Not only when accelerating undercarriages from The problem with hoists is that starting up the hanging or hanging load on the rope or chain brings, which makes it difficult to maneuver the load and also represents a hazard. Even if it works the load oscillation induced by the start Suppressing during the route can be a new one Load oscillation when braking from a high speed in a slow or maneuvering speed to be triggered. Because in general this switching from the fast driving speed into the low driving speed occurs shortly before the destination, the load swing is still in full swing when the Destination is reached. To make matters worse, at the transition from high speed to low Speed a greater jump in speed occurs than when stopping from the low speed. Thus, switching from high to high low speed represents an event in higher Dimensions of the load swing contributes than the subsequent one Stopping operation.

In addition to the problem of load swinging, induced by switching to low speed, there is a control problem when motors are used The drive of the landing gear can be used, which is a flat In other words, they have a speed-torque characteristic Engines in which the speed is very different from that Load is dependent. Such engines require one Control device and this can be adjusted by the load swing the restart of the motor current for operation with the low speed may be irritated. This leads to the fact that the regulation as a result of the Chassis leading load may be trying to greatly reduce the engine speed. After switching this would cause the vehicle speed to sag occurrence.

DE 11 13078 shows an electric drive for wheeled trolleys of hoists according to the preamble of claim 1.

Based on this, it is an object of the invention to electric drive for trolleys of hoists too create where the load swings after switching reduced from high to low speed is.

This object is achieved by the electrical Drive with the features of claim 1 solved.

According to the new solution when switching the brake from high to low speed already operated again in the sense of opening, before the low speed has actually been reached while on the other hand the power supply for the engine remains switched off. Through this measure accomplished two things at the same time. First, the hardness the transition from the deceleration phase to the driving phase significantly flattened at the low speed, with In other words, there will be large jerky changes in the current driving speed avoided. Second, there is the possibility of the load oscillation induced by braking to convert into propulsion energy of the chassis and so dampen the pendulum energy, provided, of course, the phase position is corresponding. But even if the second option does not apply because the Phase position is unfavorable, at least no additional Jerk generates the commute in an unfavorable way strengthened.

A load oscillation that can be induced by braking leaves avoid further if the brake when switching into the low speed not immediately but first is activated after a predetermined delay time, while on the other hand the power supply to the motor promptly is switched off. The landing gear is decelerated initially only due to the rolling friction of the chassis on the Rail, so that with a less pronounced kink in the state with activated or applied brake is passed over.

An advantageous control characteristic is obtained if the power supply only when reaching or falling below the low speed is switched on again. The power supply for the motor is then preferably included an amplitude average or a frequency switched on, which is smaller than it is for driving with the low one Speed is required. Such an operation is favorable if the load due to the phase position of the oscillation strives to tow the chassis.

A particularly simple drive is obtained if the motor is a main circuit universal motor and the current control device for this a phase control contains. This enables a free-wheeling characteristic to be achieved be the same in terms of pendulum damping acts like a freewheel in the drive train.

In addition, developments of the invention are the subject of subclaims.

Fig. 1

eine Blockdarstellung des erfindungsgemäßen elektrischen Antriebs und

Fig. 2

ein Flußdiagramm für die Betätigung der Bremse bzw. der Stromregeleinrichtung des Antriebs nach Fig. 1.

In the drawing, an embodiment of the object of the invention is shown. Show it:

Fig. 1

a block diagram of the electric drive according to the invention and

Fig. 2

1 shows a flow chart for the actuation of the brake or the current control device of the drive according to FIG. 1.

1 is an electrical schematic Drive 1 for trolleys of hoists illustrated. The individual electrical and mechanical assemblies are partially illustrated as function blocks, to make the essence of the invention more recognizable do.

The electric drive 1 has a motor 2 in Shape of a universal motor with an armature shaft 3, with the armature and field electrically connected in series are. As a result, the motor 2 has a main closing characteristic. Such an engine has no upper speed limit from which it could act as a generator and thus as a brake, provided the polarity between anchor and field becomes not changed.

The armature shaft 3 of the motor 2 is non-rotatable with a Input shaft 4 of a reduction gear 5 coupled, on its output shaft 6 also one of the rotationally fixed Wheels 7 of the chassis is placed on a rail 8 runs.

The shaft 3 of the motor 2 is also on the other side over and there forms a stub 9 on which one Brake disc 11 is arranged. The brake disc also works a schematically shown braking and actuating device 13 together. The brake operating device 13 is tightened by means of springs, not shown, whereby brake members (not shown) to the Put on brake disc 11 and brake or brake it. With With the help of an electromagnet, the braking device 13 against the action of the springs to be opened it Brake disc 11 to allow free running.

The braking device 13 has two electrical connecting lines 14 and 15, of which the connecting line 14 directly with a line conductor L1 of a two-phase AC network is connected, the other Phase conductor is designated L2.

The other connecting line of the magnet of the braking device 13 is via a triac 16 or a relay o. Like. Connected to the other phase conductor L2 of the network. Triac 16 receives a control signal at its gate from a control electronics 17, at the output 18 that Gate is connected.

The motor 2 is also two-pole via two lines 19, 21 connected to the two phase conductors L1 and L2, being in the connecting line 21 leading to the Phase conductor L2 leads, another triac 22 arranged is. Its gate is with an output 23 of a control device 24 connected, which serves at a corresponding Signal at an input 25 to the triac 22 control that the engine 2 with a low or a high speed runs and the engine 2 to this speed is stabilized. For this purpose, another input 26 a speed sensor, for example, sensing the output shaft 6 27 connected, the one of the speed of the Rades 7 proportional electrical signal. Because the circumference of the wheel 7 is known represents that of signal sent to the sensor 27 also the driving speed of the chassis.

To control both the control device 24 and the control circuit 17 is preferably on one Microprocessor-based electronic control 28 with two outputs 29 and 31 are provided. The output is 31 connected to the input 25, while the output 29 to leads an input 32 of the control circuit 17. Depending on Embodiment, the speed sensor 27 can also additionally be connected to the electronic controller 28.

The electronic control 28 is in turn over a multi-core connection 33 on the input side with a Switch group 34 connected via which they send their command signals receives. The switch assembly 37 can either immediately be a mechanical switch arrangement that for example housed in a control bulb of the hoist is or it represents signal states at an automatically controlled hoist from a parent Control in the electronic control 28 reach.

Deviating from the illustration, it is also possible the control device 24 on the same microprocessor implement, with whose help also the electronic Control device 28 is realized.

Since it is essentially in the present control braking is going to make understanding easier the functional description assumed that with the help the switch arrangement 34 only three signal commands the electronic control 28 can be transferred. in the In the first state, none of the switches are actuated. This corresponds to the neutral position of the switches. The second Condition corresponds to driving at low speed and is shown in the flowchart described below 2 with "D". The third state corresponds to driving at maximum speed and it is named "F" in the flow chart of FIG. 2.

The following is the working and how it works of the electric drive with the help of the flow chart of Fig. 2 explains:

If the user does not have any of the switches of the switch assembly 34 has actuated, neither state "D" still state "F" before what the electronic control causes the control device 24 to stop and in keep idle state so that they do not trigger pulses to the triac 22. The power supply to that Motor 2 is interrupted. At the same time, the Control circuit 17 also no corresponding signal from the electronic control 28, with which the triac 16 remains in the locked state. The braking device 13 is consequently closed and brakes the brake disk 11 fixed, with the result that the entire chassis braked is and cannot be moved.

If, based on this operating situation, the User operated the switches of the switch assembly 34 so that the state "F" is switched on, which means that the landing gear at its maximum speed is to run, the electronic control 28 gives the Control device 24 free and transmits it at the same time a reference value for the to be achieved and to Holding speed of the output shaft 6. The control device 24 now begins to synchronize with the AC mains voltage Output trigger pulses at output 23, whereby the triac 22 is periodically fired. The relative Position of the trigger pulse to the voltage zero crossing the network oscillation defines the current flow angle ϕ and thus the mean of the flowing current from which again the speed of the motor 2 is dependent. The Current flow angle is such from the control device 24 adjusted that the transmission output shaft 6 and the wheel 7th runs at the specified speed, independently from the burden. Simultaneously with the issue of The drive circuit also receives trigger pulses at the triac 22 17 a corresponding release signal at its input 32, with which it also begins, at its exit 18 To deliver trigger pulses to the triac 16. This will the current is switched on by the brake release magnet and the braking device 13 against the action of the biasing device released so that the brake disc 11 and in the Follow also the motor 2 can run freely and unhindered.

When the undercarriage reaches its destination with the hoist is approaching, the user from the fast driving speed switch to the low driving speed to entering the target position at slow speed, so that the target position is as accurate as any possible reached. As long as state "F" was present, is the program available in the electronic control constantly at 35 in the program section shown in FIG. 2 entered and has at a junction 36 checks whether the state "F" is present. Because by definition this driving state was switched on, was the verification always true, which means the program immediately at 37 was left again and entered other parts of the program other control tasks. To The program is the execution of these control tasks periodically returned to position 35. The times until re-entry at point 35 are because of the synchronization with the network frequency less than 10 ms.

As soon as, as assumed, the user switched from state "F" to state "D", the query condition in branch 36 was no longer fulfilled, which is why the program switched to branch 37. At this point it is checked whether the status "D" exists and whether the status "F" that was present during the last program run was. If the condition is met, the program continues in an instruction block 38 in which a timer is set to a predetermined waiting time. In practice, this waiting time is preferably between 0 and 350 ms, but can also be up to 700 ms. After the timer has been set, the program immediately continues at an instruction block 39. Here, the reference value v _soll for the speed to which the control device 24 is to adjust the speed of the motor 2 is set equal to the speed v _D which corresponds to driving at the low speed.

As explained, the user has out of quick Driving speed in the slow driving speed switched back, which means that the undercarriage brakes got to. To achieve this, an instruction block 41 the current flow angle ϕ for the triac 22 is set to zero, which means the triac 22 in the next Mains half wave in the next mains half wave no trigger pulse receives and remains locked. The timer variable w is in an instruction block 42 by a predetermined Δ reduced to get the desired stopwatch function.

In an instruction block 43 then reached there the electronic control 28 of the control circuit 17 the Command to deliver an ignition pulse to triac 16 so the brake is released as in the previous driving mode remains. To simplify the explanation, it is assumed that no other program parts are run, which is why the program after the instruction block 43 network synchronized returns to the entrance before junction 36.

Because the user is still at slow speed wants to continue, state D remains exist, i.e. the query at branch 36 lets the program continue to branch 37. Since the branch 37 is already at is run through a second time or the previous run contained state was no longer F but D, the timer variable w is no longer reset in block 38, but remains on hers in block 42 updated value and the program goes over instead of Instruction block 38 to a branch 44 at which it is checked whether state D is present. If this is the Case is in a subsequent branch 45 asked whether the time variable w for the stopwatch function is even greater than zero and if so, it comes Program now to the instruction block 39, the previous Pass from instruction block 38 reached has been. After processing instruction block 39 and the following instruction blocks 41, 42 and 43 reverse this Program for the entrance in front of branch 36 back (for the sake of simplicity, assume that between Leaving block 43 and returning to the No other program parts run through branch 36 that have something to do with the invention).

In the third run that follows, the behavior is the same the program as in the previous run. This Behavior persists until the incremental in time variable zero counted down to instruction block 42 or less than zero. The program will then start the branch point 45 to a branch point 46 pass because the condition that the state "D" is present, is still fulfilled, but the time variable in the meantime has become less than zero.

Obviously has until the time function expires the drive circuit 17 received the command, further Deliver trigger pulses to the triac 16 so that the Brake device 13 remains open.

After the end of the stopwatch function, realized with the help of the variable w, a check is made at the branching point 46 as to whether the actual speed is greater than the reference speed v _target plus a predetermined value Δ. Converted into the speed of the engine 2, this value Δ corresponds to approximately 500 rpm.

Because until the first time you reach the junction 46 the chassis only with rolling friction and Losses in the gearbox 5 is braked at the first Reaching the junction 46 the actual speed be even greater than the target speed plus Δ. The program therefore goes to the instruction block 47. At this point the electronic control 28 the control circuit 17 the command, no trigger pulse to the triac 16 so that the brake release begins to de-energize and brake against the effect the spring can no longer be kept open.

After instruction block 47, the program again returns to the input before branch 36. The run just described from the branching point 36 to the instruction block 47 is run through many times, which means on the one hand that during the runs the brake device 13 is really applied at some point and brakes the brake disk 11 appreciably, so that the chassis is significantly decelerated. The speed of the undercarriage will consequently decrease very quickly and after one of the runs the condition v _ist > v _soll + Δ will no longer be fulfilled. The program no longer goes to instruction block 47, but to branch point 48 and checks whether the actual speed has now dropped below the target speed. If this is not the case, the program again instructs the control circuit 17 at an instruction block 49 to in future issue trigger pulses for the triac 16. The brake release magnet is thereby excited and the corresponding brake members are lifted off the brake disc 11, whereby the braking effect on the brake disc 11 disappears. This disappearance of the braking effect will also take place over several program runs because of the finite response time of the braking device 13. Practical values for the brake response time are approx. 100 ms, which corresponds to ten program runs with an assumed mains frequency of 50 Hz.

As a consequence, this means that the brake is ventilated again before the low speed is achieved. The chassis is therefore not included the deceleration changes to low speed, which corresponds to the applied brake, but with one Delay caused by the rolling friction of the undercarriage Rail 8 also corresponds to that in the travel drive contained mechanical losses. To do this goes the program at branch point 48 as long as the Instruction block 49 until determined with the aid of the sensor 27 becomes the limit for the low speed is below. Leaves from this point the program branches 48 through the instruction block 51, at which the current flow angle ϕ to one of zero different, predetermined value is set. This fixed value is smaller than the current flow angle, which is necessary due to empirical tests is so that the chassis with the low target speed moves.

In addition, a variable whose verification in the program shown is not shown, set so that only run through the program shown in FIG. 2 again becomes when either state "D" disappears, and so does the state "F" does not exist or if the state "D" returns after switching to the "F" state.

For the sake of completeness, the behavior should still be of the program in the event that the Users from the fast speed immediately wants to stop, so neither the state "F" nor the state "D" is present. The program goes under these circumstances at branch 44 to an instruction block 52, which causes the current flow angle ϕ to be set to zero is held in accordance with a blocking of the triac 22. Then, at an instruction block 53, the Drive circuit 17 causes the delivery of trigger pulses to interrupt their Triac 16 so that the Brake can apply.

The described electric drive can also do this be modified that after changing from "F" after "D" immediately after query 44 to query 46 is going and the instruction block 47 the Connect described instruction blocks 39 and 41.

The advantage of the chronological sequence described consists in that at least at the end of the braking phase a slight delay is switched back, whereby the Transition from braking to driving at constant speed is less jerky. Because every jerk one Pendulum movement caused by the attached load is at the pendulum movement corresponding to reduced jerking lower. Finally, the arrangement has the advantage that after braking with the brake applied, a free-running phase that comes with an open brake, but one currentless motor 2 corresponds to the possibility there is pendulum energy to propel the undercarriage to dampen the sway, provided that of course, there is a favorable phase position the oscillation at the point of switching to Freewheeling operation.

Turning the triac 22 back on with a relative large current flow angle ϕ prevents unnecessary drop in driving speed that occurs, if for driving speed stabilization in the Control device 24 an integral controller is present. These integral controllers have a relatively high time constant and it would be without switching to the default Phase angle may be too long before the integral controller generates a current flow angle for the triac 22, with sufficient propulsion energy from motor 2 can come. If, on the other hand, the current flow angle were ϕ with which the control for motor 2 is switched on again, larger than the current flow angle that is necessary to the To run engine 2 at a speed that is greater than the desired slow speed, the braking distance would become unnecessarily longer, which means positioning of the chassis unnecessarily heavy for the user makes. The system reacts sluggishly to them commands given by the driver.

An electric drive for the undercarriage Hebzeugs contains a control that turns on the mechanical brake and switching the Controls motor current. It is provided that at one Switch from the rapid speed to the slow maneuvering speed the mechanical brake is already opened before the slow maneuvering speed completely reached or undercut. During this phase, the chassis is only with the internal friction and rolling friction on the rail are delayed, to no or no additional load swing induce.

Claims (13)

1. Electric drive (1) for running gear of hoisting devices having wheels (7),
   with a motor (2), which can be connected via transmission to at least one wheel (7) of the running gear,
   with at least one brake (11, 13), which can be assigned to one of the wheels (7) and which is to be switched back and forth between an operated and non-operated status by signals,
   with a signal transmitter array (34), which has three statuses, the first of which corresponding to stopping the running gear, tile second (D) to running at a low speed and the third (F) to running at a high speed,
   with an electronic control means (28), to which the signal transmitter array (34) is connected and which operates an electrically controllable switch (22) located in a current supply line (21) to the motor (2) and a control member (16) for the brake (11, 13),
   characterised in that the electric drive has a speed indicator (27), which supplies data concerning the speed of the running gear to the electronic control means (28), the electronic control means (28) operating the brake (11, 13) in such a manner that after a change of status of the signal transmitter array (34) from the third (F) to the second (D) status the current supply to the motor (2) is switched off and after operation the brake (11, 13) is activated in the sense of its disengagement as soon as the speed is lower than a reference value which corresponds to a speed higher than the low speed.
2. Electric drive according to Claim 1, characterised in that in the case of a switchover from the third (F) to the second (D) status, the brake (11, 13) is activated without additional delay in the sense of its application.
3. Electric drive according to Claim 1, characterised in that in the case of a switchover from the third (F) to the second status (D), the brake (11, 13) is activated with an additional delay in the sense of its application.
4. Electric drive according to Claim 1, characterised in that the motor (2) is only supplied with current again after the low speed has been reached.
5. Electric drive according to Claim 1, characterised in that upon reconnection the current has a mean value or frequency, which is smaller than that required to run at the low speed.
6. Electric drive according to Claim 1, characterised in that a motor current control means (24) connected to the speed indicator array (27) is assigned to the motor (2), by means of said motor current control means the motor current may be controlled with respect to the amplitude or frequency in the sense of keeping a predetermined motor speed constant.
7. Electric drive according to Claim 6, characterised in that the motor current control means (24) has two statuses, that in one status (D) the motor current control means (24) controls the motor current with respect to amplitude or frequency in the sense of keeping the low motor speed constant and in the other status (F) controls the motor current with respect to amplitude or frequency in the sense of keeping the high motor speed constant.
8. Electric drive according to Claim 6, characterised in that the motor current control means (24) is only switched over into the status of stabilising the low speed when the low speed is reached or fallen short of.
9. Electric drive according to Claim 1, characterised in that the motor (2) has free-wheeling characteristics.
10. Electric drive according to Claim 1, characterised in that a free-wheel is included between the motor (2) and the wheel (7) driven by the motor (2).
11. Electric drive according to Claim 1, characterised in that the motor (2) is a motor with the characteristic of a series-universal motor.
12. Electric drive according to Claim 1, characterised in that the motor current control means (24) includes a phase control means.
13. Electric drive according to Claim 1, characterised in that the brake (11, 13) is a mechanical brake.

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