JPH06135432A - Elevator - Google Patents

Abstract

PURPOSE:To optionally vary elevation speed of an elevating part as needed. CONSTITUTION:A take-up drum is provided on an elevator body, and an elevating part is coupled to a line fed from the take-up drum. The drum 15 driven to normally and reversely rotate by an induction motor 12. A frequency varying means 21 is interposed between the induction motor 12 and a commercial AC power source E. Thus power supply frequency applied from the commercial AC power source E to the induction motor 12 is selectively varied as needed. In order to secure safety for example, the power supply frequency is lowered to set elevation speed of the elevating part to a lower speed. Or when high speed is needed, the power supply frequency is raised to set the elevation speed of the elevating part to a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elevating device for elevating and lowering a lighting fixture, a speaker, etc. installed in a high place such as a ceiling of a gymnasium or factory.

[0002]

2. Description of the Related Art A lighting fixture installed in a high place such as a gymnasium or factory ceiling is mounted on a ceiling or the like so that it can be moved up and down by a lifting device so that lamp replacement, maintenance and inspection can be easily performed. ing.

In the conventional lifting device, a lifting device body is installed on a ceiling or the like, and an induction motor capable of forward and reverse driving and a winding for winding and unwinding a cord by driving the induction motor are installed in the lifting device body. A take-up drum is disposed, and a rope provided from the take-up drum is connected to an elevating part equipped with a lighting fixture.

FIG. 3 shows a drive circuit diagram of the induction motor. A switch SW is provided between the commercial AC power source E and the induction motor M, and the switch SW is connected to the contact point CW or the contact point CCW. Is driven in the forward or reverse direction. A capacitor C for starting the induction motor M is connected between the contacts CW and CCW.

For this induction motor, generally, a general-purpose four-pole reversible motor, which can drive forward and reverse rotations, is used because it is easy to reverse instantaneously and has a large starting torque. It is driven to rotate at a constant rotation speed corresponding to the frequency of the commercial power supply. That is, the rotation speed Ns can be expressed by an expression of Ns = 120f / p [rpm] (120: constant, f: frequency, p: number of poles). For example, in a 4-pole induction motor, the frequency is 50Hz. If so, Ns = 1500 [rpm].

The gear box interposed between the induction motor and the take-up drum raises and lowers the elevating section at a constant ascending / descending speed corresponding to the rotation speed of the take-up drum. Since the managers of gymnasiums and factories often perform the replacement of lamps and the like, the lifting speed of the lifting unit is set to a relatively low speed of, for example, 1 to 2 m / min in order to prevent danger.

[0007]

However, since safety management is ensured when the operator of the lifting device confirms the lifting operation of the lifting unit during construction of the lifting device or maintenance inspection after construction. The ascending / descending speed of the ascending / descending unit may be relatively high, but conventionally, since the ascending / descending speed of the ascending / descending unit is set to be relatively low and constant, there is a problem that maintenance and inspection take time.

For example, when the ascending / descending speed is 1.5 m / min and the ascending / descending distance is 15 m, it takes 10 minutes for each descending and ascending of the ascending / descending portion.

Some induction motors are capable of controlling the number of revolutions, but they are decelerated below the synchronous speed of the frequency of the commercial AC power supply and cannot be used to increase the ascending / descending speed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an elevating device capable of arbitrarily changing the elevating speed of an elevating part as needed.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a lifting device body, an induction motor provided in the lifting device body and capable of forward and reverse rotation drive, and a winding for winding and unwinding a cord by driving the induction motor. A take-up drum, an elevating part that is connected to a line drawn from the take-up drum and moves up and down by winding and unwinding the line, and frequency changing means connected between the induction motor and a commercial AC power supply. Be prepared.

[0012]

In the present invention, the power supply frequency applied from the commercial AC power supply to the induction motor is selectively and variably set by the frequency changing means as required. For example, in order to ensure safety, the power supply frequency is lowered to set the lifting speed of the lifting unit to a low speed, and when speed is required, the power supply frequency is increased to lift the lifting speed of the lifting unit. Set to high speed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of one embodiment of the present invention will be described below with reference to FIGS.

In FIG. 2, reference numeral 11 denotes a lifting device body, which is installed at a high place such as a gymnasium or a ceiling of a factory.

An induction motor 12 and a gear box 13 that is connected to the rotation shaft of the induction motor 12 and changes the rotation speed are mounted in the lifting device main body 11. The output shaft of the gear box 13 is a winding drum. 14 is installed. The take-up drum 14 has a pair of take-up portions 15, each end of a rope 16 made of, for example, one wire rope is connected to each take-up portion 15, and the rope 16 is taken up by forward and reverse rotation. It is paid out. Line
16 is led out from the take-up drum 14 through a plurality of pulleys (not shown) downward from the center of the lower surface of the lifting / lowering device body 11.

Further, a holding member is provided at the center of the lower surface of the lifting / lowering device main body 11 to be fitted and held when a lifting / lowering portion 18 described later is lifted.
17 are provided. The holding body 17 is provided with a plurality of contacts (not shown) electrically connected to the lifting unit 18 side, and detects the rising position of the lifting unit 18 and stops the drive of the induction motor 12 (not shown). A rise detection switch is provided.

The elevating part 18 is suspended and supported by the cord 16 led out from the elevating device main body 11, and a lighting fixture 19 is attached to the lower surface thereof. On the upper surface, a plurality of contacts (not shown) that are electrically connected to the lighting fixture 19 and that are connected to the contacts of the holder 17 are attached.

In the lifting device body 11, when the lifting part 18 descends, for example, when the lifting part 18 descends to the floor surface and the slack is generated in the rope 16, the slack is detected and the induction motor 12 is detected. Is provided with a descent detection switch (not shown) for stopping the driving of.

FIG. 1 shows a drive circuit diagram of the induction motor 12,
As the induction motor 12, for example, a general-purpose 4-pole / reversible motor capable of forward / reverse driving is used. The rotation speed Ns of the induction motor 12 is Ns = 120f
/ P [rpm] (120: constant, f: frequency, p: number of poles)
It is expressed by the formula.

The induction motor M is a commercial AC power source E.
Is connected via the frequency changing means 21 and the switch SW, and by connecting the switch SW to the contact point CW or the contact point CCW, the induction motor M is driven to rotate in the forward or reverse direction. A capacitor C for starting the induction motor M is connected between the contacts CW and CCW.

As the frequency varying means 21, for example, a general-purpose frequency converter is used, and the power source frequency applied from the commercial AC power source E to the induction motor 12 can be selectively varied.
Then, the frequency varying means 21 is incorporated into the lifting / lowering device main body 11 and an operation panel (not shown).

Next, the operation of this embodiment will be described.

When the elevating part 18 descends, the induction motor 12 is driven so that the cord 16 is paid out from the winding drum 14, and the elevating part 18 is lowered.
18 is lowered. Further, when the elevating part 18 is raised, the cord 16 is wound around the winding drum 14 by the reverse rotation drive of the induction motor 12, and the elevating part 18 is raised.

Then, the frequency varying means 21 selectively variably sets the power source frequency applied from the commercial AC power source E to the induction motor 12 to selectively set the lifting speed of the lifting unit 18.

When the lamp of the luminaire 19 is replaced by the manager of the gymnasium or factory, in order to prevent danger, the lifting speed of the lifting unit 18 is set to a relatively low speed. The variable means 21 does not increase or decrease the frequency of the commercial AC power supply E,
The induction motor 12 is applied with a frequency of 0 Hz. As a result, the induction motor 12 is rotated at a low speed at the rotation speed Ns = 1500 [rpm], and the elevating part 18 is moved up and down at a low speed.

When the operator of the lifting / lowering device confirms the lifting / lowering operation of the lifting / lowering unit 18 at the time of construction of the lifting / lowering device or after maintenance / inspection after the construction, for example, the frequency varying means 21 is used to switch the commercial AC power supply E. The frequency is changed to 100 Hz and applied to the induction motor 12. As a result, the induction motor 12 is rotated at a high speed at the rotation speed Ns = 3000 [rpm], and
18 goes up and down at high speed.

As described above, the frequency changing means 21 can selectively and variably set the ascending / descending speed of the ascending / descending portion 18 according to the situation. It is possible to shorten the time required to confirm the lifting operation at the time of maintenance and inspection, and improve the work efficiency.

[0028]

According to the present invention, the power supply frequency applied to the induction motor from the commercial AC power supply can be selectively variably set by the frequency changing means.
For example, to ensure safety, the power supply frequency can be lowered to set the lifting speed of the lifting unit to a low speed, and when speed is required, the power supply frequency can be increased to increase the lifting speed of the lifting unit. Can be set at high speed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a lifting device of the present invention.

FIG. 2 is a perspective view showing a mechanism of a lifting device according to the same embodiment.

FIG. 3 is a circuit diagram of a conventional lifting device.

[Explanation of symbols]

 11 Lifting device main body 12 Induction motor 14 Winding drum 16 Rope 18 Lifting part 21 Frequency changing means E Commercial AC power supply

Claims (1)

[Claims] 1. A lifting device main body, an induction motor disposed in the lifting device main body, which can be driven in a forward and reverse direction, a winding drum which winds and unwinds a cord by driving the induction motor, and a winding drum. An elevating and lowering section comprising: an elevating part that is connected to a cord that is fed out from the coil and that is moved up and down by winding and unwinding the cord; and a frequency varying unit that is connected between the induction motor and a commercial AC power source. apparatus.