JPH0773437B2 - Electric chain block with speed control - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric chain block with speed control in which a speed of hoisting and lowering is variable by speed control of a motor that drives a load sheave.

(Prior Art) Conventionally, disclosed in Japanese Utility Model Laid-Open No. Sho 62-189389, and
As shown in the figure, a charge / discharge circuit (A) having a variable resistor (VR) and a capacitor (C) and a charge / discharge circuit (A) are set in a control circuit of a motor (M) for driving a load sheave. A gate signal output unit (D) that outputs a gate signal according to a time constant, and a bidirectional switching element unit (T) that chops the AC voltage applied to the rectifier (B) by the gate signal every half cycle. Speed control circuit (X)
By adjusting the variable resistor (VR), the voltage value supplied to the motor (M) is changed to change the speed of the motor (M).

In FIG. 7, (E) is an AC power supply, and (F) is a reverse circuit that changes the polarity of the supply voltage by switching between winding up and winding down.

(Problems to be Solved by the Invention) In the speed control circuit (X) described above, the gate signal is output by repeatedly charging / discharging the capacitor (C) every half cycle of the AC power supply, and chopping the AC waveform. In Although,
For example, even after the gate signal is output at a certain timing in the positive half cycle of the AC power source and the charge charged in the capacitor (C) is discharged, the charge is still discharged before the next negative half cycle. Since there is no guarantee that all the charged electric charges will be lost, when the negative polarity is entered and the charging of the capacitor (C) is to be started again, the initial electric charge remaining in the capacitor (C) causes the previous positive charge. Charging will be started under conditions different from the half cycle of. Therefore, in the negative half cycle, the gate signal is output at a timing different from that in the positive half cycle, which causes imbalance in the positive and negative chopping waveforms. Therefore, the voltage supplied to the motor (M) fluctuates, and stable speed control is difficult to perform.

In particular, at a low speed in which the variable resistor (VR) is increased to increase the time constant of the charge / discharge circuit (A) and the gate signal is output in the latter half of the half cycle of the AC power supply, the capacitor (C) is used. Has a large residual charge, and the positive and negative imbalance of the chopping waveform based on the residual charge significantly appears. Therefore, actually, it is extremely difficult to reduce the chopping waveform to 30% or less with respect to the sine wave of 100%, and therefore, the voltage supplied to the motor (M) cannot be lowered to a certain level or less, The lower limit of the speed control width was restricted, making it difficult to meet diverse needs.

Moreover, this type of chain block is equipped with a mechanical brake mechanism such as a screw type so that the load sheave rotates freely in the direction in which the load is applied and does not fall freely. It suffices to give a small load to the motor (M) to release the mechanism one by one, but as described above, the lower limit of the low speed is suppressed, so the motor (M) must be driven with an excessive load. In addition, a difficulty also occurs in terms of the life of the motor (M).

An object of the present invention is to correct an imbalance between positive and negative chopping waveforms, enable stable low speed control, widen the range of speed control, and perform an aptitude control with speed control capable of performing aptitude control matching various needs. To provide.

(Means for Solving the Problem) Therefore, the present invention includes a motor (2) for driving the load sheave (1), which makes it possible to adjust the speed of the motor (2), and the motor (2) and the load. An electric chain block with speed control, in which a mechanical brake (25) for braking a slip in the down direction is interposed in the power transmission mechanism between the sheave (1) and a charge / discharge circuit having a resistor and a capacitor. (3), a gate signal output section (4) for outputting a gate signal every half cycle of the AC power supply at a timing according to the time constant of the charge / discharge circuit (3), and the gate signal output section (4) And a bidirectional switching element unit (5) for chopping the AC power supply every half cycle by the output of
A speed control circuit (6) for controlling the speed of the motor (2) by changing the effective value of the voltage supplied to the motor (2) is provided, and the charging / discharging circuit (6) is repeated every half cycle of the AC power supply. After the discharge of the capacitor in 3), a reset circuit (7) for resetting the initial charge remaining in the capacitor to an equal level in the positive half cycle and the negative half cycle is provided, while the charge / discharge circuit (3) is provided. , It has been decided to provide means for lowering the speed at the time of unwinding by switching in conjunction with the hoisting and unwinding switches (SU, SD) and making the time constant during unwinding larger than that at the time of hoisting.

(Operation) In the reset circuit (7), the initial charge remaining in the capacitor of the charge / discharge circuit (3) is reset to the same level in the positive half cycle and the negative half cycle. The capacitor can be charged from the same initial state both when going to the negative half cycle and when going from the negative half cycle to the positive half cycle. As a result, the gate signal can be output from the gate signal output unit (4) at the same timing according to the set time constant for both positive and negative, and the bidirectional switching element unit (5) can perform even chopping of the AC power source, and the chopping waveform Positive and negative imbalances can be corrected and a wide range of speed control from high speed to low speed can be performed stably.

In particular, the time constant of the charging / discharging circuit (3) is made larger than that at the time of hoisting by the speed lowering means at the time of hoisting, and the voltage supplied to the motor (2) at the time of hoisting is equal to that at the time of hoisting. Since it can be lowered more than anything, it can be decelerated so that it can be slowed down with sufficient force to loosen the mechanical brake (25), and the life of the motor (2) can be maintained for a long time. Even during the lowering, in which the time constant is increased, the reset circuit (7) can correct the imbalance of the output waveform, and an appropriate low speed control during the lowering can be realized.

(Embodiment) In the electric chain block shown in FIGS. 4 and 5, a DC motor (2) is arranged on one side of the chain block body (100), and a drive shaft (20) of the motor (2) is arranged. Is interlocked with the load sheave (1) via a gear reduction mechanism consisting of first to fourth gears (21) to (24) and a mechanical brake (25) for braking slip in the down direction, The overload prevention mechanism is provided on the intermediate shaft (26) provided with the second and third gears (22) and (23) constituting the reduction mechanism.

That is, the first gear (21) is provided at the shaft end of the drive shaft (20), and the second gear (22) meshing with the first gear (21) is the intermediate shaft (26). The boss portion (29) of the first hub (28) screwed to the screw portion (27) is rotatably supported, and one side of the second gear (22) is connected to the hub (28). An annular friction plate (31) is interposed so as to face the flange (30), and the boss (29) of the first hub (28) is splined to the other side of the second gear (22). A push plate (33) which is coupled and is pressed by the disc spring (32) in the direction of the second gear (22) is arranged, and between the push plate (33) and the second gear (22). With an annular friction plate (34),
Based on the friction transmission force set by the disc spring (32),
The power transmitted to the second gear (22) is transferred to the push plate (3
The overload preventing mechanism is configured so that the load is transmitted from 3) to the first hub (28) and slips when the load acting on the load sheave (1) exceeds the friction transmission force.

The third gear (23) is provided at the shaft end of the intermediate shaft (26) via the step (35), and the third gear (23) and the first hub (28) are connected to each other. A second hub (36) is arranged between the two, and is screwed to the intermediate shaft (26),
The reverse rotation preventing ratchet wheel (38) that constitutes the mechanical brake (25) is rotatably supported on the boss portion (37) of the hub (36), and the reverse rotation preventing ratchet wheel (38) and the first hub (28). ) Flange (30) and the flange (3) of the second hub (36).
An annular friction plate (40) (41) is interposed between the same and 9), and a reverse rotation preventing claw (42) is arranged outside the outer peripheral portion of the reverse rotation preventing claw wheel (38). The reverse rotation preventing claw wheel (38) and the reverse rotation preventing claw (42) are arranged, and the reverse rotation preventing gear (38) and the reverse rotation preventing claw (42) constitute a mechanical brake (25).

Further, the fourth gear (24) meshing with the third gear (23)
Is attached to the cylindrical shaft (43) integral with the load sheave (1).

Then, in the case of winding, the second rotation is performed by the normal rotation of the motor (2).
The first hub (28) holding the gear (22) is moved to the right in FIG. 4 along the screw portion (27), and the second hub (36) is locked to the right to lock the friction plate (41). Intermediate driven gear (22)
Is transmitted to the rotation of the intermediate shaft (26) and further to the rotation of the third gear (23), and the load sheave (1) is rotated in the winding direction via the fourth gear (24). At this time, reverse rotation prevention ratchet (38)
Is rotated in the sliding direction of the reverse locking pawl (42) and the intermediate shaft (2
The rotation of 6) is not hindered. Further, if the hoisting load exceeds a predetermined value, the second gear (22) is moved to the friction plates (31) (34).
Slide between to avoid rotation lock of motor (2).
Thus, when the motor (2) is stopped at an arbitrary height, the reverse rotation preventing ratchet wheel (38) is engaged with the reverse rotation locking hook (42),
The rotation of the intermediate shaft (26) is restricted to prevent the hoisted luggage from falling.

On the other hand, in the case of unwinding, the motor (2) is rotated in the reverse direction and the first hub (28) holding the second gear (22) is moved to the left along the screw part (27) in the figure to prevent the reverse rotation ratchet wheel. Friction plate of (38) (40)
The holding at (41) is loosened to release the rotation restraint of the reverse rotation preventing ratchet wheel (38) on the intermediate shaft (26), and the intermediate shaft (26) is released.
Load sheave (1)
Allow the descent of. Then, the rotation of the intermediate shaft (26) again causes the first rotation.
Move the hub (28) to its original position to the right, and
The rotation of the intermediate shaft (26) is restrained by locking the reverse rotation locking claw (42) of 8) to prevent a sudden drop of luggage. By safely restraining the reverse rotation preventing ratchet wheel (38) to the intermediate shaft (26) and releasing the same, the unwinding is safely performed. At this time, the motor (2) needs only a small load to generate a torque to move the first hub (28) to the left against the disc spring (32).

The motor (2) provided in the chain block configured as described above is controlled by the control circuit shown in FIG. The control circuit uses a commercial AC power source (E) as a power source and includes a speed control circuit (6), a rectifying circuit (8), a reversing circuit (9), and a switching operation circuit (10).

The speed control circuit (6) has four variable resistors (VR1-4)
And switching contacts (Ry3-a, Ry3-
b, Ry4-a, Ry4-b) and a resistance circuit (3a) having a fixed resistance (R1), a charge / discharge circuit (3) in which a capacitor (C2) is connected in series, and the charge / discharge circuit (3). A gate signal output section (4) using a bidirectional trigger diode (SSS) that outputs a gate signal every half cycle of the AC power supply (E) at a timing according to a time constant, and the gate signal output section (4) And a bidirectional switching element section (5) using a triac (Trc) that chops the AC power supply (E) every half cycle by the output from the motor, and the effective value of the supply voltage to the motor (2), Is to change the DC voltage value after passing through the rectifier circuit (8). In the charging / discharging circuit (3), after the capacitor (C2) is repeatedly discharged every half cycle of the AC power source (E), the initial charge remaining in the capacitor (C2) is charged with a positive half cycle and a negative half cycle. A reset circuit (7) for resetting to the same level is provided. This reset circuit (7) is configured by using four diodes (D1 to 4) and two fixed resistors (R2) (R3). In addition, the bidirectional trigger diode (SS
In front of S), fixed resistor (R4) and capacitor (C3)
It has an operational stabilization circuit consisting of a parallel circuit.

The rectifier circuit (8) includes a bridge-type full-wave rectifier (DB) and a smoothing capacitor (C5), makes the polarity of the AC voltage chopped by the speed control circuit (6) uniform, and supplies the voltage to the motor (2). Is converted to direct current.

The reverse rotation circuit (9) reverses the polarity of the DC voltage supplied to the motor (2) by switching the switching operation circuit (10) between winding up and winding down, thereby rotating the motor (2) forward or backward. It is a thing.

The switching operation circuit (10) has a low speed (L) with a single pressing operation,
Two-step push-up switch (SU) and down switch (SD) that can be switched between high speed (H) by two pressing operations.
And a hoisting relay (Ry1) that is excited by turning on the hoisting switch (SU), two hoisting relays (Ry2) (Ry3) that are excited by turning on the hoisting switch (SD), and , And a high-speed relay (Ry4) that is excited by pushing up and down switches (SU) (SD) in two stages.

In addition, load resistance (R5) is placed between the terminals of the motor (2).
And the normally-closed contacts (Ry1-b) (Ry2-b) of the hoisting and lowering relays (Ry1) (Ry2) are connected in series, and the hoisting or lowering switch (SU) (SD) The load circuit is configured when the motor (2) acts as a generator when the power is turned off to cut off the power supply to the motor (2). Also, the variable resistors (VR3) (VR4) in the resistance circuit (3a) are operated by the operation switches (SU, S
It is provided in the operation box (11) together with (D, SH) etc. and is open to the user side.

The case of performing the winding up or the winding down with the above configuration will be described.

When winding up, turn on the winding up switch (SU). The hoisting relay (Ry1) is excited and the contact (Ry1) of the reverse circuit (9)
-A) (Ry1-a) is closed and the motor (2) is connected to the forward rotation side. Further, the contact (Ry3-b) of the resistance circuit (3a) is maintained in the normally closed state by the non-excitation of the lowering relay (Ry3), and the variable resistance (VR1) is short-circuited.

When performing this hoisting, when selecting the high speed by pushing the hoisting switch (SU) in two stages, the high speed relay (Ry4) is excited and the normally open contact (Ry4-a) of the resistance circuit (3a) is turned on.
The normally closed contact (Ry4-b) is turned off, and the resistance component (RUH) of the charge / discharge circuit (3) is the sum of the set value of the variable resistor (VR4) and the fixed resistor (R1) (RUH = VR4 + R1). ). On the other hand, when low speed is selected by pushing the hoisting switch (SU) in one step, the resistance component (RUL) of the charging / discharging circuit (3) has two fixed resistances (VR3) (VR2) and fixed resistance. (R1) is the sum (RUL = VR3 + VR2 + R1). Since the time constants (τ1) (τ2) of the charge / discharge circuit (3) are proportional to the product of the resistance component (RUH) or (RUL) and the capacitor (C2),
As shown in FIG. 2, the timing until the terminal voltage (v) of the capacitor (C2) reaches the break potential (Vb) of the trigger diode (SSS) by setting the variable resistors (VR2 to 4). Can be changed. Here, the resistance component (RUL) when low speed is selected and the resistance component (RU) when high speed is selected
By making it larger than H), the time constant (τ2) at low speed selection can be made larger than that at high speed (τ1), so the trigger diode (SSS) reaches the break potential (Vb) and the triac (Trc). The timing of outputting the gate signal can be delayed. Therefore, the area of the chopping waveform in the triac (Trc) can be reduced, the effective value of the voltage supplied to the motor (2) can be reduced, and the motor (2) can be rotated at a lower speed than when high speed is selected.

For lowering, turn on the lowering switch (SD). Excitation of the lowering relay (Ry2) causes the contact (Ry2) of the reverse circuit (9)
-A) (Ry2-a) is closed, and the motor (2) is connected to the reverse rotation side. Also, the variable resistance (V
R1) is added as a resistance component of the charge / discharge circuit (3). Therefore, as shown in FIG. 3, the time constant (at the time of pushing in SD2 step) and the time constant (at the time of pushing SD1 step) at both high speed (when pushing in SD1 step) is increased by the addition of this variable resistance (VR1) as compared with the time when hoisting. τ3) (τ4) can be increased (τ3> τ1)
(Τ4> τ2), the output timing of the gate signal by the trigger diode (SSS) can be delayed, the area of the chopping waveform in the triac (Trc) can be further reduced, and the motor (2) can rotate at an extremely low speed. become. That is, the unwinding speed reducing means is configured by inserting the variable resistor (VR1) into the charging / discharging circuit (3) during unwinding.

Here, as the break point of the trigger diode (SSS) is delayed and the chopping waveform due to the triac (Trc) is made smaller, the problem of waveform imbalance between the positive polarity and the negative polarity becomes greater, but the reset circuit (7) causes
Both polar imbalances can be eliminated.

That is, in FIG. 3, in a certain positive half cycle (T1),
After operating the trigger diode (SSS), the positive potential (+ e) appearing at the terminal (BP) in Fig. 1 due to the electric charge remaining in the capacitor (C2) changes to the next negative half cycle (T2). The diode (D3) and the fixed resistor (R3) that form the reset circuit (7) at the time when the polarity changes to the negative polarity after the transition
Will be immediately lost to the negative line (a1) side. On the other hand, the negative potential (−e) that appears at the terminal (BP) in the negative half cycle (T2) is positive in the next positive half cycle (T3) via the diode (D2) and the fixed resistor (R2). It will be neutralized and disappeared by receiving positive charge from the line (a1) on the side. Furthermore, in these positive half-cycles (T1) (T3) and negative half-cycles (T2), the zero potential (third potential) based on the residual charge of the other polarity that tends to appear on the line (a2) side of the capacitor (C2), respectively. The difference in the offset voltage from the electric potential on the horizontal axis in Fig. 3 (b) depends on the series circuit of the diode (D1) and the fixed resistor (R2) and the series circuit of the diode (D4) and the fixed resistor (R3). It will be forcibly clamped to the equipotential.

Therefore, when switching from the positive half cycle to the negative half cycle (T1 → T2) and when switching from the negative half cycle to the positive half cycle (T2 → T3), the capacitor (C2) The terminal voltage (v) can be adjusted to an equipotential near 0 potential, and the capacitor (C2) can be charged from the same initial state of positive and negative, and at the same timing according to the set time constant for both positive and negative. The trigger diode (SSS) can reach the break potential, the triac (Trc) can be turned on evenly, and the positive and negative imbalance of the chopping waveform can be corrected. By the way, with the provision of the reset circuit (7), the lower limit of the chopping waveform can be reduced to about 5% for a sine wave of 100%, and wideband control becomes possible.

Needless to say, this imbalance correction of the chopping waveform can be performed not only at the time of winding, but also at the time of winding.

As described above, it is possible to stably control the speed of the motor (2) in a very wide range from high speed to low speed, and moreover, it is possible to perform high speed and low speed for both winding and winding, and further, the motor (2) The torque applied to the motor is reduced to a small amount required to release the mechanical brake (25). During the unwinding, the variable resistance (VR1) is surely decelerated to reduce the load on the motor (2). Therefore, the life of the motor (2) can be kept long.

In the embodiment shown in FIG. 1, the hoist or hoist switch (SU)
Variable resistance (VR4) by high-speed selection by pushing (SD) two steps
, And the series line of two variable resistors (VR3) (VR2) are switched. However, as shown in FIG. ), A variable resistor (VR5) independent of the line, and a contact (Ry4-b) that is closed when high speed non-selection, that is, low speed selection.
A variable resistor (VR6) is provided on each line with a variable resistance (VR5), and the upper limit of high speed when the highest speed is selected and high speed is selected. When selected, the rate of deceleration may be adjusted by a variable resistor (VR6) to simplify the circuit and operation.

(Effects of the Invention) As described above, in the present invention, the reset circuit (7) resets the initial charge remaining in the capacitor of the charge / discharge circuit (3) to the same level in the positive half cycle and the negative half cycle of the AC power supply. You can
A gate signal can be given from the gate signal output section (4) to the bidirectional switching element section (5) at the same timing according to the set time constant for both positive and negative, which can correct the positive and negative imbalance of the chopping waveform. A wide range of speed control from high speed to low speed can be stably performed, and sufficient deceleration can be performed especially at the time of unwinding where load reduction is required, which can contribute to the improvement of the life of the motor (2).

[Brief description of drawings]

FIG. 1 is a control circuit diagram of an electric chain block according to the present invention, FIG. 2 is a diagram showing control waveforms of various parts at the time of winding, and FIG. 3 is a diagram showing control waveforms of various parts at the time of winding. FIG. 5 is a side sectional view of the chain block, FIG. 5 is a VV sectional view thereof, and FIG.
FIG. 7 is a principal part view showing another embodiment, and FIG. 7 is a control circuit diagram of a conventional example. (1) …… Load sheave (2) …… Motor (3) …… Charging / discharging circuit (4) …… Gate signal output section (5) …… Bidirectional switching element section (6) …… Speed control circuit ( 7) …… Reset circuit (25) …… Mechanical brake (SU) …… Up switch (SD) …… Down switch

Claims (1)

[Claims] 1. A motor (2) for driving a load sheave (1), the speed of the motor (2) being adjustable, and the power between the motor (2) and the load sheave (1). A charging / discharging circuit (3) having a resistance and a capacitor, which is an electric chain block with speed control, in which a mechanical brake (25) for braking a slip in a winding direction is interposed in the middle of a transmission mechanism, and the charging / discharging circuit. A gate signal output unit (4) that outputs a gate signal every half cycle of the AC power supply at a timing according to the time constant of (3), and an AC power supply every half cycle by the output from the gate signal output unit (4). And a bidirectional switching element unit (5) for chopping
A speed control circuit (6) for controlling the speed of the motor (2) by changing the effective value of the voltage supplied to the motor (2) is provided, and the charging / discharging circuit (6) is repeated every half cycle of the AC power supply. After the discharge of the capacitor in 3), a reset circuit (7) for resetting the initial charge remaining in the capacitor to an equal level in the positive half cycle and the negative half cycle is provided, while the charge / discharge circuit (3) is provided. , With speed control, which is equipped with a lowering speed lowering means that switches in conjunction with the hoisting and lowering switches (SU, SD) and makes the time constant during unwinding larger than that during hoisting Electric chain block.