JPS6332712B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for remotely controlling a truck crane.

Conventionally, there has been a drive device for a truck crane as shown in FIG. In the figure, P is a pump that is a pressure fluid source, and E is an engine that drives pump P, which is driven by the excitation force of the rotation speed control solenoid 13 of the accelerator positioner AP connected to the accelerator AC via a cable C. The rotation speed is controlled. 2 is an electromagnetic flow control valve connected to the pump P. 3, 4, 5, 6 are electromagnetic directional valves,
It is connected in parallel to the electromagnetic flow control valve 2.

The electromagnetic directional control valve 3 is connected to an actuator W for raising and lowering a hook of a truck crane.
is the boom extension/retraction actuator X, and the electromagnetic directional control valve 5 is the boom hoisting actuator Y.
The electromagnetic directional switching valves 6 are respectively connected to the swing actuators Z and supply and discharge pressure fluid. These electromagnetic directional control valves 3, 4, 5, 6 are in neutral position 3a,
4a, 5a, 6a, left switching position 3b, 4b, 5
b, 6b, right switching positions 3c, 4c, 5c, 6c, and left switching solenoids 3d, 4d, 5d,
When 6d is excited, the left switching position 3b, 4
b, 5b, 6b, right switching solenoid 3
When e, 4e, 5e, and 6e are excited, they are in right switching positions 3c, 4c, 5c, and 6c, and supply and discharge pressure fluid to and from the actuator, respectively. In addition, these electromagnetic directional switching valves 3, 4, 5, 6, when the left and right switching solenoids are not excited,
They are held at neutral positions 3a, 4a, 5a, and 6a, respectively.

The flow control valve 2 includes electromagnetic directional control valves 3, 4, 5,
6, and controls the amount of pressure fluid supplied to the flow rate detection section 20, flow rate control section 21, and solenoid valve section 2.
Consists of 2. The electromagnetic valve section 22 controls the vent pressure of the flow rate control section 21, and has a flow rate control solenoid 23. Electromagnetic directional valve 3, 4,
When either of 5 and 6 is switched to the left or right switching position, the unload passage 15 is blocked, and the flow rate control solenoid 23 is energized, the flow rate in the passage 25 is changed according to the excitation force of the solenoid 23. The flow rate of the pressurized fluid flowing out to the bridge passage 29 through the throttles 27 and 28 and the solenoid valve part 22 is restricted, and the pressure in the spring-side pilot part of the flow rate control part 21 increases due to this flow of pressure fluid, so that it is discharged from the passage 25. The flow rate flowing into tank T via passage 30 is restricted. Therefore, the pressure fluid in the passage 25 has a flow rate of
It flows out from the detection part 20 to the passage 26. The pressure in the supply passage 26 acts on the solenoid section 23 via the bridge passage 29. Therefore, the flow rate control valve 2 causes a flow rate corresponding to the excitation force of the flow rate control solenoid 23 to flow out into the supply passage 26 .

A device for remotely controlling the drive device shown in FIG. 1 is an operation panel 34 connected to the control panel 32 via a cable.
It is equipped with The operation panel 34 has a lever 36 for raising and lowering the hook, a lever 38 for extending and retracting the boom, a lever 40 for raising and lowering the boom, a lever 42 for turning, and a dial 44 for engine presetting. The levers 36, 38, 40, and 42 generate electrical signals according to the amount of operation and the direction of operation (U or D) from their neutral positions. Further, the dial 44 generates an electric signal according to the amount of operation thereof.

The control panel 32 includes electromagnetic directional valves 3, 4, 5, 6.
Switching solenoids 3d, 3e, 4d, 4e, 5
d, 5e, 6d, and 6e, and a first drive circuit for exciting the flow control solenoid 23 of the electromagnetic flow control valve 2 and the rotation speed control solenoid 13 of the engine E. 48, and further includes a second drive circuit 50 for exciting the rotation speed control solenoid 13 of the engine E.

The comparison circuit 46 includes comparison circuits 52 and 54 that receive electrical signals from the lever 36, comparison circuits 56 and 58 that receive electrical signals from the lever 38, and comparison circuits 52 and 54 that receive electrical signals from the lever 36,
and comparison circuits 64 and 6 that receive electrical signals from the lever 42.
It has 6. These comparison circuits 52, 54, 56,
The output signals of 58, 60, 62, 64, 66 are output from solenoids 3d, 3e, 4d, 4e, 5d, 5e,
Transistors 68, 70, 72, 74, 76, 78, 80, connected in series to 6d and 6e, respectively.
It is supplied to 82 bases. comparison circuit 52,
56, 60, 64 are levers 36, 38, 40,
42 in the U direction, and when the amount of operation becomes larger than a predetermined setting value, an output signal "1" is generated. Also, comparison circuits 54, 58, 62, 66
operates the levers 36, 38, 40, and 42 in the D direction, and generates an output signal "1" when the amount of operation becomes smaller than a predetermined setting amount.

The first drive circuit 48 includes levers 36, 38, 4
The output signals of these pulse width modulation circuits 84, 86, 88, 90 are used for electromagnetic flow control via an OR circuit 92. valve 2
It is supplied to the base of a transistor 94 connected in series with the solenoid 23 of the engine, and is further supplied via an OR circuit 96 to the base of a transistor 98 connected in series with the engine speed control solenoid 13. There is. The pulse width modulation circuits 84, 86, 88, 90 are connected to each lever 36,
After the comparator circuits 52, 54, 56, 58 output an output signal "1" regardless of the operating direction of the levers 38, 40, 42, a pulse signal having a width corresponding to the amount of lever operation from the neutral position is output. Therefore, the larger the manipulated variable, the wider the pulse width. Since the configuration of this pulse width modulation circuit is well known, detailed explanation will be omitted.

The second drive circuit 50 includes a pulse width modulation circuit 100 that receives an electrical signal from the dial 44 , and the output signal of this pulse width modulation circuit 100 is supplied to the base of a transistor 98 via an OR circuit 96 . This pulse width modulation circuit 100 is configured similarly to the pulse width modulation circuits 84, 86, 88, and 90. In addition, 102 is a solenoid 3d,
3e, 4d, 4e, 5d, 5e, 6d, 6e, 1
This is a power supply circuit for 3 and 23.

The operation of such a conventional remote control device will be explained. First, it is assumed that the levers 36, 38, 40, and 42 are in neutral positions, and the dial 44 is operated by a predetermined amount. A pulse signal corresponding to the operation amount of the dial 44 is transmitted from the pulse width modulation circuit 100 to the OR circuit 9.
6 to the base of the transistor 98, and the rotation speed control solenoid 13 is energized.
The engine E rotates at a predetermined rotation speed, and the pump P discharges pressure fluid at a predetermined discharge flow rate.

For example, in this state, if the hook lifting lever 36 is operated in the U direction by more than a set amount, the comparator circuit 52 generates an output signal "1" and the transistor 68 becomes conductive. As a result, the switching solenoid 3d is energized, and the electromagnetic directional switching valve 3 is switched to the left switching position 3b. Furthermore, the electric signal of the hook lifting/lowering lever 36 is transmitted to a pulse width modulation circuit 90, and after switching to the electromagnetic direction switching position, the pulse width modulation circuit 90 generates a pulse signal with a pulse width corresponding to the amount of operation of the lever 36. Transistor 94,9
8. As a result, the excitation state of the rotational speed control solenoid 13 changes and the rotational speed of the engine E increases in accordance with the operation amount of the lever 36, and the flow rate control solenoid 23 is excited and the lever 36 is operated. The flow rate control valve 2 supplies pressure fluid to the electromagnetic directional switching valve 3 in accordance with the amount, and this pressure fluid is supplied to the actuator W to raise the hook. To return it to its original position, operate the lever 36 in the D direction. The same applies when the other levers 38, 40, and 42 are operated.

In the conventional device described above, the rotation speed of the engine E is preset by operating the dial 44, so if any one of the levers 36, 38, 40, 42 is operated beyond the preset amount, the rotation speed of the engine E is preset. The number of revolutions increases, the operating speed of the crane increases, and the moving speed of the crane can quickly follow the lever operation. However, even if the levers 36, 38, 40, and 42 are returned to the neutral position, the engine only returns to a higher rotation speed than the preset rotation speed, and the engine E is noisy and there is a lot of wasted pressure fluid consumption. There was a problem.

This problem is caused by hysteresis in the solenoid current vs. position characteristic for speed control of the accelerator positioner AP and hysteresis due to friction in the cable C connecting the accelerator positioner AP and the accelerator lever of the engine E.
This is because the accelerator lever AC of the engine E does not return to its original position even if the current value to the AP rotation speed control solenoid is returned to the preset current value.

Therefore, the present invention has been developed to operate a crane by operating a control lever with the engine speed preset to raise the engine speed above the preset value, and then when the control lever is returned to the neutral position, the engine speed is increased. The technical challenge is to return the value to the preset value.

The technical means of the present invention for achieving this technical problem is to provide a gate circuit between the second drive circuit and the rotation speed control solenoid in the conventional device, and normally send a gate open signal to the gate circuit. The present invention is to provide a gate drive circuit which responds to the disappearance of the output of the comparator circuit and causes the gate open signal to disappear for a certain period of time.

According to this technical measure, since the gate is always open, the rotation speed control solenoid can be energized.
You can preset the engine. Then, the gate is closed for a certain period of time from when the comparison circuit loses its output, that is, from the time when the operating lever returns to the neutral position, and the rotation speed control solenoid is demagnetized for a certain period of time. Therefore, after the engine speed decreases to idle speed or near the preset speed, the engine speed is controlled to the preset speed again. Therefore, the above-mentioned technical problem can be achieved without being affected by the above-mentioned hysteresis.

This invention having the above technical means has the following unique effects.

Another technical means to achieve the above technical problem is to install a position detector for position feedback in the accelerator positioner itself, and output signals from the operation panel (output signals from dials and operation levers).
It is also possible to consider a configuration in which the engine speed is set to a preset value by comparing the signal from the position detector for position feedback and controlling the accelerator positioner so that the deviation value becomes zero.

However, according to this other technical measure, the engine speed does not change in response to the position of the accelerator positioner without any time difference, but has a constant time difference until it stabilizes at the position of the accelerator positioner. Therefore, there is a problem in that the above-mentioned time delay is involved until the engine speed reaches the preset value.

In contrast, according to the present invention, the signal to the solenoid for controlling the rotation speed of the accelerator positioner is temporarily set to zero and then raised to the preset value again, so that the engine rotation speed can be rapidly brought to the preset value. It has a unique effect.

Hereinafter, an embodiment in which the present invention is constructed using a logic circuit will be described based on FIG. Incidentally, the same parts as those of the conventional one shown in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted. In FIG. 3, 104 is an AND gate interposed between the pulse width modulation circuit 100 and the OR circuit 96. This and gate 1
The gate open signal to 04 is sent to the gate drive circuit 106.
given from. Gate drive circuit 106 includes an inverter 108 and a one-shot multivibrator 110. The one-shot multivibrator 110 has comparison circuits 52, 54, 56, 58, 60, 62, 64,
66 output signals are provided. The one-shot multivibrator 110 includes comparison circuits 52, 5
The output signal "1" is generated for a predetermined period in response to the fall of the output signals 4, 56, 58, 60, 62, 64, and 66. Note that the resistor 114 connected in series with the dial 44 is for matching the operation amount of the dial 44 and its electrical signal.

Next, the operation of this embodiment will be explained. It is now assumed that the operating levers 36, 38, 40, and 42 are in neutral positions, and the dial 44 is in a non-operating state. In this state, one-shot multivibrator 1
The output signal of inverter 10 is "0", and its inverted output, the output signal of inverter 108, is "1", and AND gate 104 is open. Therefore,
By operating the dial 44, the engine E
can be preset to a predetermined rotation speed.

In this state, the levers 36, 38, 40,
42, for example, the lever 36, is operated in the U direction, the comparison circuit 52 generates an output signal "1", the pulse width modulation circuit 90 generates a pulse signal, and the hook is raised. When the lever 36 is returned to the neutral position, the comparator circuit 52 loses the output signal "1". As a result, the one-shot multivibrator 110 generates an output signal "1", and its inverted output "0" is supplied to the AND gate 104, which closes, the solenoid 13 is demagnetized, and the rotational speed of the engine E is The speed drops to near idle or preset speed. After a certain period of time, one-shot multivibrator 1
The output signal 10 becomes "0", and the inverted output "1" opens the AND gate 104, the rotational speed control solenoid 13 is energized again, and the rotational speed of the engine E increases to the preset value. The same applies when operating other levers.

In the above embodiment, a dial was used to preset the rotational speed of the engine E, but an operating lever may also be used. Furthermore, if the preset value is always constant, a resistor with a constant resistance value and a normally open switch connected in series can be used in place of the dial.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram of a truck crane drive system, FIG. 2 is an electric circuit diagram of a conventional truck crane remote control device, and FIG. 3 is an electric circuit diagram of an embodiment of a truck crane remote control device according to the present invention. It is a circuit diagram. E...Engine, P...Pump (pressure fluid source), 2
...Solenoid flow control valve, 3,4,5,6...Solenoid directional switching valve, 36,38,40,42...First lever type command member, 44...Second command member, 52,54,5
6, 58, 60, 62, 64, 66...comparison circuit,
84, 86, 88, 90...Pulse width modulation circuit (first drive circuit), 100...Pulse width modulation circuit (second drive circuit)
(drive circuit), 104...AND gate, 106...gate drive circuit.

Claims (1)

[Claims] 1. An engine whose rotation speed is controlled in response to the excitation force of a rotation speed control solenoid, a pressure fluid source driven by this engine, and a pressure fluid source connected to this pressure fluid source that responds to the excitation force of a flow rate control solenoid. an electromagnetic flow control valve that responds to control the discharge flow;
An electromagnetic directional switching valve is connected to the control valve and switches the supply/discharge direction of the truck crane driving actuator to a first supply/discharge direction and a second supply/discharge direction by energizing a switching solenoid; is a first lever-type command member that can be operated in a second opposite direction and generates a first electric signal according to the operation direction and amount of operation; and a first lever-type command member that inputs the first electric signal. The operating direction of the member is determined, and if the operating direction is a first direction, the pressure fluid flows to the actuator in a first supply/discharge direction, and if the direction is a second direction, the pressure fluid flows to the actuator in a second supply/discharge direction. a comparison circuit that transmits an electric signal to the switching solenoid; and a comparison circuit that inputs a first electric signal to determine the amount of operation of the first lever-type command member so that the discharge flow rate and the number of revolutions increase in accordance with the amount of operation. a first supplying an electric signal to the flow rate control solenoid and the rotation speed control solenoid;
a drive circuit, a second command member that generates a second electric signal according to the operation amount, and a second command member that inputs the second electric signal and generates a second electric signal according to the operation amount;
A remote control device for a truck crane comprising a second drive circuit that determines the operation amount of the command member and supplies an electric signal to the rotation speed control solenoid so that the rotation speed increases in accordance with the operation amount. 2. A gate circuit interposed between the drive circuit and the rotation speed control solenoid, and a gate opening signal normally supplied to this gate circuit, which is set in advance in response to the disappearance of the electric signal from the comparison circuit. A remote control device for a truck crane, characterized in that it is provided with a gate drive circuit that erases the gate opening signal for only a period of time.