JPS6117758B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zero-gravity hoist that creates an apparent zero-gravity state by controlling the current of an excitation coil in a hoist drive power transmission system, and particularly relates to an automatic sensitivity device that speeds up the landing time. This is related to switching.

The present applicant has already used a differential circuit to detect temporal changes in wire rope tension when a suspended load takes off and lands on the floor, in order to shorten the work as much as possible when a suspended load takes off and lands on the floor. A zero-gravity hoist is provided in which the current of the excitation coil of the hoist drive transmission system is increased within a certain period of time to accelerate the speed at which a suspended load takes off and lands on the floor.
In addition, in the above proposal, even after the suspended load reaches an equilibrium state and floats, and the differential circuit becomes inactive, a balance correction circuit is installed to prevent the constants of the control circuits of each part from changing thermally. I was using it.

However, since the differentiating circuit is used to detect changes in the rope tension at the time of landing on the floor and accelerating the increase/decrease of the electromagnetic clutch current, the sensitivity of the differentiating circuit must be kept relatively high. However, the influence of the nozzle on the input side of the differentiating circuit is large, and a time delay element is added to the differentiating circuit in order to eliminate this effect. Therefore, the output of the differential circuit, which should be zero when the suspended load floats, causes a drift.
In order to quickly correct this, the sensitivity of the balance correction circuit must also be increased.

By the way, during levitation, if the sensitivity of the balance correction circuit is set relatively high, it becomes difficult to correct the balance. At the same time, the differential circuit also detects sideways movement of the load sensor, making it increasingly unstable.

In view of the above problems, the present application aims to provide a zero-gravity hoist that enables highly accurate and stable operation by automatically disconnecting the differential circuit from the control circuit at the moment of levitation of a suspended load.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic front view of one embodiment of a zero gravity hoist. Reference numeral 1 denotes a hoist body, which is supported by a traveling beam 3 via a traveling vehicle 2. 4 is a jib equipped with a control panel 5, and this control panel 5 is powered on.
A switch 6, a power OFF switch 7, and a lowering switch 8 are provided. Reference numeral 9 denotes a wire rope, one end of which is wound around a later-described drum of the hoist main body 1, and the other end is connected to a load sensor 11 via a hook block 10. A suspended load 13 is suspended from the hook block 10 via a switch holding member. A movable contact holding member 18 is provided with a rising movable contact 16a and a descending movable contact 17a via a spring 15 on the upper and lower support frames 14 of the switch holding member 12.
is swingably attached. The fixed contact holding member 19 of this switch holding member 12 is provided with a rising fixed contact 16b and a lowering fixed contact 17b corresponding to the movable contacts 16a and 17a.
b) The lowering switch 17 (17a, 17b) is turned on by grasping the handle 20 by hand and moving the holding member 18 up and down.

FIG. 2 is a circuit configuration diagram of a torque transmission system control device of the present invention for controlling the zero gravity hoist. In FIG. 2, a reduction gear 31, an electromagnetic clutch 32, a drum 33, and a brake 34 are installed in series on the extension of the rotating shaft of an induction motor 30, which is a drive source, and as described above, a wire rope 9
One end is wound around the drum 33, and the other end is held and connected to the load sensor 11 via the hook block 10. The load sensor 11 is configured such that, for example, a strain gauge is assembled into a bridge circuit and can be converted into an electrical output corresponding to the detected load. 35 is a preamplifier, and 36 is a differentiating circuit. A signal corresponding to the detected load from the load sensor 11 is input to this differentiating circuit 36 via the preamplifier 35. 42 is a differential amplifier, and the output end of the differentiating circuit 36 is connected to its inverting input terminal via a resistor R ₁₁ , a normally closed contact Aa, a parallel circuit 46 for signal switching, and a normally open contact A ₁ '. There is. _R12
is resistance. Parallel circuit 4 for switching the above signals
6 is formed by connecting a series circuit of a diode D ₁ and a normally open contact D _b and a series circuit of a diode D ₂ and a normally open contact U _b connected in parallel. Also, this parallel circuit 4
The input side of 6 is connected to a power supply -Vcc as a signal source for rising, which outputs a signal for rising, through a normally closed contact A2 _' . Here, regarding each of the above-mentioned contacts, the normally open contacts U _b and D _b are linked to the operation of the up switch 16 and the down switch 17, respectively, and the normally open contact A ₁ ' and the normally closed contact A ₂ ' is linked to relay A'. Here, relay A' constitutes a detection unit that detects whether the load of the zero gravity hoist is less than the tare weight load.
For example, when the load of the zero gravity hoist is slightly larger than the tare weight load, the electromagnetic clutch 3
The excitation current of No. 2 is set as a set value, and is energized when the excitation current is equal to or higher than the set value, and deenergized when it is lower than the set value. The normally open contact A ₁ ' and the normally closed contact A ₂ ' form a switching circuit, and when the relay A' is de-energized, the switching circuit changes the power supply -Vcc to a time integral storage device (described later). 45 to supply a rising signal thereto, and when relay A' is energized, the power supply -Vcc is disconnected from the time integral storage device 45 and the differentiating circuit 36 is connected thereto. The output signal is supplied to a time integral storage device 45. 37
is a pattern detector, and its input end is connected to the input side of the parallel circuit 46. This pattern detector 37 detects the load of the suspended load 13 and the wire rope 9.
It emits an output when a balance with the tension is established, and it consists of a detection circuit such as a zero-cross detector, and a circuit that generates a trigger pulse when the detection circuit detects it.

The output terminal of the pattern detector 37 is connected to the base of a switching transistor 38, and the collector of this transistor 38 is connected to a relay A. The normally open contact A _b is for self-holding of the above relay A, and the light emitting diode 39 is normally lit, but is turned off by the operation of the normally closed contact A _c , which is turned off by the energization of the above relay A, and the light is turned off during work. This light emitting diode 39 is provided so that a person can visually check the light emitting diode 39 to know whether the balance between the suspended load 13 and the wire rope 9 is established. Also, a normally closed contact _A a on the line connecting the differentiating circuit 36 and the differential amplifier 42
is activated by relay A.

The input end of the balance correction circuit 40 is connected to the power supply -Vcc via a resistor R ₉ and a contact point U _a that is linked to the operation of the switch 16 for lifting the suspended load 13, and also connected to the power supply -Vcc via a resistor R ₉ . It is connected to the power supply +Vcc via a normally open contact D _a that is linked to the operation of the load lowering switch 17 . Further, the output terminal of the balance correction circuit 40 is connected to the inverting input terminal of a differential amplifier 42 via a resistor _R10 .

Reference numeral 45 denotes a time integral memory device such as an analog memory element, and the output voltage of the time integral memory device 45 is a signal proportional to the time integral value of the input signal, which is output and held. Reference numeral 46 denotes a control circuit for the electromagnetic clutch 32, in which a built-in PUT oscillation circuit (not shown), for example, is oscillated by the output of the time integral storage device 45, and as a result, the electromagnetic clutch 32
The gate of a thyristor inserted into the excitation coil is controlled to control the current in the excitation coil.

Next, the operation of the embodiment having the above configuration will be explained. Now, with the suspended load 13 completely on the floor,
For example, the lifting switch 1 of the switch holding member 12
When 6 is turned on, the excitation coil of the lift relay is attached to close the lift contacts U _a and U _b , and the relay coil for the brake 34 is also energized, closing its contact B _a . Thus, the drum 33 is released from the brake state. At this time, since the excitation current of the electromagnetic clutch 32 is less than the above set value, the relay A' is demagnetized, so the normally open contact _A1 ' and the normally closed contact _A2 ' are in the open and closed states, respectively. ing. Therefore, the pattern detector 37 does not emit an output signal because its input side is connected to the power supply -Vcc via the normally closed contact A ₂ '. As a result, the relay A becomes demagnetized, so the normally closed contact A _a is closed, and the differential amplifier 42 has the following information: power supply -Vcc → normally closed contact A ₂ ' → parallel circuit 46 → normally closed contact A _a → Resistance R ₁₁
A large current flows through the path. As a result, the output signal of the time integral storage device 45 rises with a large slope, and the excitation current of the electromagnetic clutch 32 increases accordingly. As a result, the amount of transmission from the electromagnetic clutch 32 increases, so that the drum 33 rotates in the direction of raising the suspended load 13, and the wire rope 9 is wound up. Immediately before the suspended load 13 leaves the floor, the excitation current exceeds the previously mentioned set value, that is, the value corresponding to a load slightly larger than the tare weight, so the relay is activated.
A' is energized, which causes normally open contact A ₁ ' and normally closed contact A ₂ ' to close and open, respectively. On the other hand, at this point, a part of the load of the suspended load 13 is detected by the load sensor 11 as the tension of the wire rope 9, and since the change in tension is large, an even larger output signal is generated from the differentiating circuit 36 instead of the power supply _-Vcc . It flows into the differential amplifier 42 through a similar path. Therefore, the voltage peak value of the time integral storage device 45 becomes high and the output becomes large in a short time, and the input to the control circuit 46 also increases rapidly, so that the excitation current of the electromagnetic clutch 2 becomes large in a short time. The suspended load 13 leaves the floor at a rapid rate.

When the suspended load 13 is completely removed from the floor, the output of the load sensor 11 becomes equal to the constant load of the suspended load 13, so the output of the differential circuit 36 disappears. Therefore, the pattern detector 37 detects the disappearance of the above output, generates a trigger pulse as an output signal, drives the switching transistor 38 to turn ON, energizes the relay A of the collector circuit, and closes its self-holding contact. Ab is closed, and the normally closed contact A _a is opened to disconnect the output terminal of the differential circuit 36 and the input terminal of the differential amplifier 42 . At the same time, normally closed contact A of relay A is energized by relay A.
_c is opened to turn off the lit light emitting diode 39. The switch 43, which is always on, can be manually turned off when landing on the bed.
The self-holding of relay A is released and the differential circuit 36 is used to reset the wire rope so that it can accelerate the loosening of the wire rope. On the other hand, after the differentiating circuit 36 is disconnected,
A minute output signal from the balance correction circuit 40 is input to the inverting input terminal of the differential amplifier 42, and in response to this, the output signal of the time integral storage device 45 gradually increases, and the suspended load 13 slowly rises. do.
When the suspended load 13 has risen to an appropriate height, the worker operates the lifting switch 16 to open the normally open contact U _a . Then, the lowering switch 17 is operated to close the normally open contact D _a for a certain period of time, thereby inputting a signal of opposite polarity to the time integral storage device 45 and decreasing the input integral amount. The suspended load 13 is then stopped.

Next, when the lowering switch 17 is turned on, the normally open contact D _a is closed, and the power supply +Vcc is connected to the inverting input terminal of the differential amplifier 42, so that a predetermined positive output is output to the time integral storage device 45. The output of this time integral storage device 45 is supplied to the control circuit 46. Therefore, the excitation current of the electromagnetic clutch 32 is controlled to decrease, and the drum 33 is controlled to reduce the suspended load 13.
The wire rope 9 is lowered and rotated in the direction of lowering the wire rope.

When the wire rope 9 is lowered and a part of the suspended load 13 lands on the floor, the tension of the wire rope changes and this is detected by the load sensor 11, and at this point the above-mentioned case when the suspended load 13 leaves the floor occurs. Similarly, an output is obtained from the differentiating circuit 36.
Therefore, the output signal from the pattern detector 37 disappears, and the normally closed contact A _a is closed. As a result, the output signal from the differentiating circuit 36 is introduced into the inverting input terminal of the differential amplifier 42, the output of the differential amplifier 42 becomes large, and the potential stored in the time integral storage device 45 rapidly changes in a short period of time. As a result, the excitation current of the electromagnetic clutch 32 via the control circuit 46 becomes small in a short time, and the suspended load 13 quickly lands on the floor.

In the embodiment described above, the disconnection means for disconnecting the differential circuit and the rising signal source from the time integral storage device is constituted by the transistor 38, the relay A, and the normally closed contact A _a .

As described above, according to the present invention, changes in the tension of the wire rope are detected by a differential circuit and the excitation current of the electromagnetic clutch is controlled based on the output. The increase/decrease of the excitation current can be accelerated, the time taken to take off and land the suspended load on the floor can be accelerated, and the working time can be shortened. Moreover, since the differentiating circuit is separated from the driving force transmission system to the wire rope when lifting a suspended load, the negative effects of the differentiating circuit can be removed when performing balance correction, enabling highly accurate and stable operation. Ta. In addition to the configuration of the present invention, as in the embodiment shown in Fig. 2, if it is possible to check the moment of leaving the bed, that is, the point at which the balance between the suspended load and the lifting torque by the electromagnetic clutch is established, by means of a lamp instruction, it will be psychologically It can give you a sense of relief. In other words, since the establishment of the balance can be visually checked, even unskilled workers can easily carry out the work. For example, when using this method to unload a bar after lathe-machining, it will be easier to remove the chuck and core extrusion. There are great practical advantages, such as being able to check the balance of the bar to be unloaded with a small gap using the lamp indication.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view of one embodiment of a zero-gravity hoist, and FIG. 2 is a circuit configuration diagram of a torque transmission system control device of the present invention for controlling the zero-gravity hoist shown in FIG. 1. 1...Hoist body, 11...Load sensor,
13... Hanging load, 16... Lifting switch, 17
... Lowering switch, 30 ... Induction motor, 32
...Electromagnetic clutch, 33...Drum, 34...Brake, 35...Brain amplifier, 36...Differential circuit, 37...Differential circuit output pattern detector, 38
... Switching transistor, 39 ... Light emitting diode, 40 ... Balance correction circuit, 42 ...
Differential amplifier, 43... switch, 45... time integral storage device, 46... control circuit.

Claims (1)

[Claims] 1. A drum is connected to the rotating shaft of the drive motor via an electromagnetic clutch, a suspended load is suspended on the drum via a wire rope, and the tensile load of the wire rope is measured by a load sensor. detecting the load sensor, inputting a signal corresponding to the output of the load sensor to a time integral memory device, and controlling the excitation current of the electromagnetic clutch by a control circuit that generates a signal corresponding to the output from the time integral memory device; In a zero-gravity hoist that achieves an apparent zero-gravity state of the suspended load by balancing the load of the suspended load and the tension of the wire rope, the differential circuit detects the rate of change over time of the load detected by the load sensor. , a signal source for rising that outputs a signal for rising, a detection unit that detects whether the load of the zero gravity hoist is less than or equal to the tare weight load, and between the time integral storage device and the differentiation circuit, and between the time integral storage device and the rising When the load detected by the detection section is less than or equal to the tare load, a signal for rising is supplied to the time integral storage device, and when the load exceeds the tare weight, the signal source for rising is connected to the time integral storage device. is separated from the time-integral storage device and connected to the differentiating circuit to supply the output signal of the differentiating circuit to the time-integral storage device; a pattern detector that produces an output when a balance with the tensile force of the wire rope is established; and an output signal from the pattern detector to disconnect the differential circuit and the rising signal source from the input side of the time integral storage device. A zero-gravity hoist comprising a separating means.