JPS6363477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a speed control method for a variable speed hoist, and particularly to a speed control method for a variable speed hoist having an inverter.

[Conventional technology]

The conventional speed control method for variable speed hoisting machines is as follows:
As shown in Japanese Patent Application Laid-Open No. 57-1193, the inverter can be operated by connecting the motor to a power source via an inverter, connecting a speed variable device to the inverter, and changing the set speed of the speed variable device. It is known to vary the speed of a motor by varying the output of the motor.

[Problem to be solved by the invention]

The speed control method of such a conventional variable speed hoist is as follows:
The speed of the motor can be changed steplessly to obtain the optimal speed for normal work, but since the speed increases continuously to the speed set by the speed variable device at startup, workability and stability at startup are reduced. It had problems in terms of.

An object of the present invention is to provide a speed control method for a variable speed hoist that is excellent in terms of workability and stability at the time of startup, and that can obtain the optimum speed for work after startup. be.

[Means to solve the problem]

The present invention connects a motor 10 to a power source 30 via an inverter 20, connects a speed variable device 40 to the inverter 20, and changes the set speed of the speed variable device 40 to control the output of the inverter 20. In the speed control method for a variable speed hoist, which changes the speed of the motor 10 by changing the The set speed of the motor 10 is set lower than the set speed of the speed variable device 40, and the motor 10 is operated at a low speed with the speed setting device 50 at the time of startup, and then the motor 10 is operated at a high speed by switching to the speed variable device 40. This is a speed control method for a variable speed hoist, characterized in that:

[Effect]

According to the speed control method of such a variable speed hoist,
A speed setting device 50 switchably connected to the speed variable device 40
is connected to the inverter 20, the set speed of the speed setter 50 is set lower than the set speed of the speed variable switch 40, and the speed setter 50 is connected to the motor 10 at startup.
Since the motor 10 is operated at a low speed and then switched to the speed variable device 40 to operate the motor 10 at high speed, you can get used to the work by operating at a low speed using the speed setting device 50 at startup, and by switching to the speed variable device 40, the motor 10 can be operated at a high speed. It is possible to shift to the high speed operation set by the device 40. This can greatly improve workability and safety during startup. In addition, after starting, by changing the speed setting of the speed variable device 40, the speed can be adjusted to suit the type of work being performed.
It also has excellent workability in this respect.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Motor 1 which is the drive source of the hoist shown in Fig. 1
0 is a three-phase induction motor. The motor 10 is connected to output terminals U, V, and W of an inverter 20. The rotational speed of this motor 10 is determined by the inverter 2
Varies depending on the output frequency of 0. Inverter 2
Input terminals R, S, and T of 0 are connected to terminals 30R, 30S, and 30T of a commercial AC power supply 30, respectively.

The inverter 20 includes a converter section 21, an inverter section 22, and a voltage/frequency command section 23, as shown in FIG. The converter section 21 obtains a constant DC voltage by inputting the commercial AC power supply 30. The inverter section receives this DC voltage and obtains rectangular wave AC outputs U, V, and W. The voltage and frequency of the rectangular wave AC outputs U, V, and W are determined according to the voltage/frequency command signal input from the voltage/frequency command section 23 to the inverter section 22. This voltage
The frequency command signal is determined according to the DC voltage between the input terminals 20L and 20M determined by the speed variable device 40 or the speed setting device 50. The input terminal FR of the inverter 20 is a signal input terminal for reversibly rotating the motor 10 by switching the order of phase rotation of the rectangular wave AC outputs U, V, W, and when 0V is input, the motor 10 rotates in the reverse direction. The speed variable device 40 consists of a variable resistor, one end of which is connected to the input terminal 20H of the inverter 20 via a switch 71 and a first switch 60 which are connected in series.
The other end of the speed variable device 40 is connected to the inverter input terminal 20L via a switch 72.

The variable end of the speed variable device 40 is connected to the input terminal 20M of the inverter 20, and inputs a DC signal to the voltage/frequency command section 23 of the inverter 20.

This DC signal can change the resistance value of the variable resistor by rotating the knob externally, and the DC voltage between the input terminals 20L (0V) and 20M of the inverter 20 can be changed continuously from 0.5V to 5V. There is.

In response to this change in DC voltage from 0.5V to 5V,
The outputs U, V, and W of the inverter section 22 have a frequency of 10
Hz to 60Hz, and the rotation speed of motor 10 changes from 360 rpm to 360 rpm according to this frequency change.
It is now possible to change up to 2160 rpm.

The speed setter 50 is composed of a semi-fixed variable resistor. One end of this speed setting device 50 is connected to a connection point between the switch 71 and the first switch 60 via a switch 73. Speed setting device 5
The other end of 0 is connected to the inverter 2 via the switch 74.
0 input terminal 20L. The variable end of the speed setting device 50 is connected to the input terminal 20 of the inverter 20.
M, and inputs a DC signal to the voltage/frequency command section 23 in the same way as the variable end of the speed variable device 40. While the speed variable device 40 varies the DC signal from the variable end by arbitrarily rotating a knob from the outside, the speed setting device 50 fixes the DC signal to a predetermined value and does not allow external input. The only difference is that they cannot be operated, but the other configurations are the same.

The speed setter 50 operates at a constant low voltage (e.g.
0.5V) is input to the inverter 20, and the hoisting machine is operated at low speed. This low speed operation can be set to a low speed convenient for inching operation, a minimum speed of the motor that generates the rated torque of the motor 10, or any other speed desired by the user. The speed variable device 40 has its minimum output voltage matched with the output voltage (for example, 0.5V) of the speed setting device 50, and can be changed to a value higher than the minimum voltage of the speed variable device 40 by operating a knob.

The reversing switch 80 is a switch that reverses the rotational direction of the motor 10, and has one end connected to the input terminal 20L and the other end connected to the input terminal FR of the inverter 20. This reversing switch 80 is closed by the energization of the reversing relay coil 80L, and receives 0V.

The magnetic brake 90 releases the braking force on the motor shaft when energized, and is connected to the commercial AC power terminal 3 via the brake switch 91.
Connected to 0R, 30S, brake switch 91
The magnet coil 91L that opens and closes the switch 6
Controlled by 2.

The first switch 60 is composed of a relay contact, and is closed when the relay coil 60L is energized, and opened when the relay coil 60L is deenergized. Relay coil 60L is activated by closing low speed upper switch 60U or closing low speed lower switch 80D.
It is energized by closing the switch 81 with 0L, and deenergized by opening it.

The second switch 70 is composed of switches 71, 72, 73, and 74, which are relay contacts. The switch 71 and the switch 72 are each opened when the relay coil 70L is energized, and closed when the relay coil 70L is deenergized. The relay coil 70L is energized by closing the high-speed upper switch 70U or the lower high-speed switch 70D, and is deenergized by opening it.

The opening and closing operations of the switches 71 and 72 of the second switch 70 and the opening and closing operations of the switches 73 and 74 are always opposite to each other.

Further, the switch 62 is closed when the relay coil 60L is energized, and closed when the relay coil 60L is deenergized.

FIG. 3 is a perspective view of the floor push button operation box 41 that controls the motor 10.

Both the upper push button 61 and the lower push button 81 are operation parts of a two-stage push button switch. This two-stage push button switch has a structure in which the first stage switch is closed by pressing the button to the first stage, and the second stage switch is closed by continuing to push the button to the second stage. When the upper push button 61 is pressed to the first stage, the low speed upper switch 60U is closed, and by continuing to press it to the second stage, the high speed upper switch 70 is closed.
U is also closed. When the lower push button 81 is pressed to the first stage, the low speed switch 80D is closed, and when the lower push button 81 is continued to be pressed to the second stage, the high speed lower switch 70D at the second stage is closed.

The knob 42 can be rotated to adjust the speed variable device 40.
The resistance value of the resistor can be varied. While holding down the upper push button 61 or the lower push button 81 to the second step,
By rotating the knob 42, the motor 1
0 rotation speed can be varied. If you release the pressure from the second stage, it will return to the first stage.

Next, the operation of such a variable speed hoist will be explained.
When the motor 10 is operated in normal rotation, first, by pushing the upper push button 61 to the first stage, the low speed upper switch 60U is closed and the relay coil 60L is energized. When the relay coil 60L is energized, the relay switch 62 is closed, and the magnet coil 91L is energized by electricity from the power source 30. The brake switch 91 is actuated by this biasing of the magnetic coil 91L, and the magnetic brake 90, which brakes the rotation of the motor 10, is released.

At the same time as the magnetic brake 90 is released, the first
switch 60 is closed. In this case, switch 73 and switch 74 are in a closed state.

Therefore, the speed setting device 50 and the inverter 20
The input terminal 20L of the inverter 20 is connected to the voltage/frequency command unit 23 of the inverter 20 and is set to low speed in advance.
The motor 20 rotates at a low speed due to the DC voltage between and 20M.

Next, press the upper push button 61 to the second stage and keep pressing it to close the high speed switch 70U and energize the relay coil 70L.
The second switch 70 consisting of is closed. At the same time, switch 73 and switch 74 are opened. In this case, the first switch 60 is in a closed state. Therefore, the speed variable device 40 and the voltage/frequency command unit 23 of the inverter 20 are connected, and the rotational speed of the motor 10 is changed by operating the knob 42 of the speed variable device 40. When the upper push button 61 is released, each switch returns to its original state and the motor 10 stops.

A case where the motor 10 is operated in reverse will be explained. When the lower push button 81 is pushed to the first step, the low speed lower switch 80D is closed and the relay coil 80L is energized. By energizing this relay coil 80L, relay switch 80 is closed and converter 2
0 input terminal FR becomes 0V, the order of phase rotation of the motor 10 is switched, and the rotation direction of the motor 10 is changed. Furthermore, the energization of the relay coil 80L closes the relay switch 81 and energizes the relay coil 60L. Other operations are the same as described above.

The speed of this motor 10 and the first switch 6
FIG. 4 shows the relationship between the opening and closing operations of the switch 0 and the second switch 70.

Curve A in FIG. 4 shows the speed of motor 10. That is, first, when the upper push button 61 or the lower push button 81 is pushed to the first step, the first switch 60 is closed and the motor 10 rotates at a constant low speed.

Next, by continuing to press the upper push button 61 or the lower push button 81 to the second stage, the second switch 70 is closed, and by rotating the knob 42 of the speed variable device 40, the motor 10 rotates at a variable speed. Further press button 6
When the pressure on the 1 or lower push button 81 is released, the second switch 70 is opened and rotation starts at a constant low speed.

In this way, the first switch 60 enables the speed setter 50 to obtain the rotational speed of the motor 10 at a constant low speed desired by the user, and the second switch 70 enables the speed variable device 40. Since the rotational speed of the motor 10 can be changed continuously and a speed commensurate with the work is obtained, a variable hoist with excellent workability can be obtained.

In addition, the first switch 60 and the second switch 7
By performing the 0 operation using an integrated two-stage push button switch, a variable speed hoist with excellent operability can be obtained.

Furthermore, the constant output of the speed setting device 50 is set to the motor 1.
By setting the motor to the lowest speed that generates a rated torque of 0, a variable speed hoist that can safely and easily perform an inching operation can be obtained.

According to the speed control method of such a variable speed hoist,
A speed setting device 50 switchably connected to the speed variable device 40
is connected to the inverter 20, the set speed of the speed setter 50 is set lower than the set speed of the speed variable switch 40, and the motor 10 is
Since the motor 10 is operated at a low speed and then switched to the speed variable device 40 to operate the motor 10 at high speed, you can get used to the work by operating at a low speed using the speed setting device 50 at startup, and by switching to the speed variable device 40, the motor 10 can be operated at a high speed. It is possible to shift to the high speed operation set by the device 40. This can greatly improve workability and safety during startup. Furthermore, after starting, the speed can be adjusted to suit the type of work by changing the set speed of the speed variable device 40.
It also has excellent workability in this respect.

〔Effect of the invention〕

According to the present invention, it is possible to provide a variable speed hoist that is excellent in terms of workability and safety at the time of start-up, and can obtain an optimum speed for work after start-up.

[Brief explanation of drawings]

Fig. 1 is an electric circuit diagram of the variable speed hoist used in the present invention, Fig. 2 is an explanatory diagram of the inverter part of the variable speed hoist, and Fig. 3 is a floor push button operation box of the variable speed hoist. FIG. 4 is an explanatory diagram of the operation of the variable speed hoist. 10...Motor, 20...Inverter, 30
...power supply, 40...speed variable device, 50...speed setting device, 70...switch.

Claims (1)

[Claims] 1. Connecting the motor 10 to a power source 30 via an inverter 20, connecting a speed variable device 40 to the inverter 20, and changing the set speed of the speed variable device 40 to change the output of the inverter 20. In the speed control method for a variable speed hoisting machine, the speed setting device 50 is switchably connected to the speed variable device 40.
is connected to the inverter 20, the set speed of the speed setter 50 is set lower than the set speed of the speed variable device 40, and the speed setter 50 is set at a lower speed than the set speed of the speed variable device 40.
A method for controlling the speed of a variable speed hoist, characterized in that the motor 10 is operated at a low speed, and then the speed variable device 40 is switched to operate the motor 10 at a high speed.