JPS6141745Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electric circuit that automatically controls the acceleration generated when a hoist is lowered under load without requiring any special equipment.

The conventional descending speed braking circuit, as shown in FIG.
It is configured as follows: armature 2 - field winding 1 - alternating current power supply 7, and when descending, by switching the lift selector switch 5, the polarity of the current supplied to the armature 2 is reversed compared to when ascending. I was getting used to it. For this reason, acceleration occurs when the fishing load is lowered, and a friction plate has been used mechanically or electromagnetically to control this. However, these devices are accompanied by various instability, dangers, and equipment burdens, such as the need for an extremely powerful braking force device due to wear of the friction plates, failure of operational functions, or progressive acceleration. Now I have a flaw.

The present invention has been developed to solve the above problems, and has a simple structure without using a mechanical braking device. The purpose is to provide a gradual descent braking circuit for aircraft.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a circuit diagram of this embodiment, in which the same components as those in the circuit shown in FIG. 1 are given the same reference numerals.

The contacts of the lift changeover switch 5 in FIG. 2 indicate the state when the hoist is in the lowered state. That is, in this embodiment, when the hoisting machine is lowered, the series circuit of the rectifying element 3 and the electric load 4 is connected to the main electric circuit shown in FIG. Armature 2 at connection points A and B
When the hoisting machine is raised, the series circuit of the rectifying element 3 and the air load 4 is short-circuited through the contacts 5a and 5b of the lift changeover switch 5, and the armature 2 is connected in parallel to the lift changeover switch 5a'. , 5b' to invert the polarity.

With the above configuration, during work in this embodiment, the braking force and driving force from the single-phase AC power supply 7 are divided into a half cycle of driving action due to energization and a half cycle for braking action, as shown in FIG. The relationship is as follows.

(a) Reference line of acting force (zero) during non-energizing period (b) Acting waveform of motor driving force due to energization (c) Average motor driving force (d) Waveform for generated electric braking action (e) Average braking force In other words, When the hoisting machine descends, the upper half-wave of the AC voltage at zero volts acts as a motor, and the lower half-wave acts as a brake.
It lowers by repeating driving and braking. In other words, the average motor driving force (c) is α
Assuming that field 1 is excited in the remaining half wave of the action waveform (a) of the electric driving force due to energization, and the generated average braking force (o) is β, then α>β, and the driving torque by the power supply is applied to armature 2 every half wave.
Therefore, in a half-wave of drive, the current i ₁ forms a normal motor drive circuit through field 1 and armature 2, as shown in FIG. 4a. However, due to the polarity of the rectifier 3, no current flows to the electrical load 4. Therefore, the schematic diagram is as shown in FIG. 4b, and the average driving force is as shown in FIG. 4c.

In the half-wave of braking, as shown in FIG. 5a, when lowering the suspended load, a current i ₂ acts as an exciting current in the field 1. When the force of the suspended load to rotate the armature 2 becomes stronger than the rotation of the armature 2, a current i ₃ that cancels out the current i ₂ ' that had flowed into the armature 2 to some extent actually flows into the armature 2. The current i ₂ + (i ₃ − i ₂ ′) is generated as a back electromotive force of the child 2 and flows to the rectifier 3.
flows, and a braking force corresponding to the current (i ₃ −i ₂ ′) is applied to the armature 2. To simplify this, if we ignore the electrical load 4, which has a smaller value than the impedance of the armature 2, Figure 5a becomes Figure 5b, and Figure 5c is the equivalent circuit of Figure 5b. it is conceivable that. The remaining half of the average braking excitation force shown in FIG. 4c excites the field 1 to generate an average braking force β to the armature 2 as shown in FIG. 5d.

In addition, during braking half-wave, if there is no suspended load,
In Fig. 5a, the force that causes the armature 2 to be circuited at high speed due to the suspended load is eliminated, so the current
A current i ₃ sufficient to cancel out i ₂ ′ is not generated. Therefore, the braking force is still weak and the motor is driven as an electric motor. In this way, the descending operation is characterized by driving and braking, generating a braking force according to the load, and exerting an acceleration prevention function to keep the rotation constant. be.

Therefore, for this acceleration prevention operation, if the adjustment of the load amount of the electric load 4 is set in advance,
The speed limit according to the command is automatically obtained. For this purpose, the present application uses a method that has already been proposed, that is, a DC motor is used as the hoisting machine, and when descending with a load applied, braking is performed entirely by power generation depending on the load, and therefore a power cutoff relay is used. This method is significantly different from other methods, which tend to be expensive.

As explained above, this device completely eliminates device failures and accidents caused by acceleration by completely eliminating mechanical control devices, and therefore, it significantly reduces equipment costs by simplifying the structure, and at the same time automates work. This has led to the realization of extremely excellent effects, such as making the equipment more robust.

[Brief explanation of drawings]

The drawings show an embodiment of this invention; Fig. 1 is an electric circuit diagram of the prior art, Fig. 2 is an electric circuit diagram of this invention, and Fig. 3 is a waveform representation of the driving force during operation of this invention. , Fig. 4 is an explanatory diagram of the driving force of the present invention, Fig. 4 a and b are its circuit diagrams, Fig. 4 c
5 is a diagram showing the driving force, FIG. 5 is an explanatory diagram of the braking force of the present invention, and FIGS. 5 a, b, and c are the circuit diagrams,
FIG. 5d is a diagram showing the braking force. 1... Field, 2... Armature, 3... Rectifying element,
4...Electrical load, 5...Elevation changeover switch, 6...
...AC series motor, 7...Single-phase AC power supply.

Claims (1)

[Scope of utility model registration request] In a hoist using an AC series-wound motor driven by a single-phase AC power source, a changeover switch is provided to change the armature polarity of the hoist when switching between raising and lowering the hoist. , Only when descending by the changeover switch, a series circuit consisting of a rectifier and an electric load for adjusting acceleration during descending is connected in parallel to the armature winding, and when descending, each half wave of the single-phase AC power supply is connected in parallel. A slow-down braking circuit for hoisting machines that is characterized by repeated driving and braking.