JP2000240604A - Revolving controller in construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid decrease in the revolving speed or delayed return of a control valve to the neutral position, in relieving the sudden acceleration at the start of revolving motion. SOLUTION: A pilot passage for connecting pilot valves 16A, 16B to a control valve 12 is provided with an electromagnetic proportional switching valves 17A, 17B for restricting the pressure of the oil supplied from the pilot valve to the control valve 12 in correspondence to detection signals from a boom angle sensor 21 and an arm angle sensor 22 for detecting the attitude of a working part and with first check valves 18A, 18B for flowing the oil from the control valve 12 to the pilot valves without restricting the oil pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a turning control device for a construction machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art Generally, in a construction machine having a revolving structure such as a hydraulic shovel, the moment of inertia during turning greatly varies depending on the posture of a working unit mounted on the upper revolving structure. In other words, for example, as shown by the solid line in FIG. 1, when the bucket 7 is in the small reach posture near the turning center O, the moment of inertia is small, and as shown by the chain line in FIG. In the case of a large reach position that is far away, the moment of inertia increases.
By the way, pressure oil supply control to a turning motor that drives to turn the revolving body is generally controlled by a control valve that operates by receiving pilot pressure oil output from a pilot valve based on operation of an operating tool. However, the pressure of the pilot pressure oil output from the pilot valve is set in accordance with the large reach posture so that turning operation can be smoothly performed even when the working unit is in the large reach posture having a large moment of inertia. It had been. For this reason, when the working unit is in the small reach posture having a small moment of inertia, the acceleration at the time of turning start becomes large, which may cause a problem that a lever hunting phenomenon occurs or that soil or the like loaded on the bucket spills. Was.

[0003]

Therefore, a posture detecting means for detecting the posture of the working unit is provided, and a control valve such as an electromagnetic pressure reducing valve or a throttle valve is provided in a pilot oil passage from the pilot valve to the control valve. It is proposed that the control valve is arranged to operate based on a detection signal from the attitude detecting means. However, in this case, when the electromagnetic pressure reducing valve is used, the pressure of the pilot pressure oil supplied to the control valve decreases, so that there is a problem that the turning speed decreases, and when the throttle valve is used, When the turning lever is operated from the turning position to the neutral position to stop the turning operation, the oil discharged from the control valve flows through the throttle valve to the pilot valve, and the discharged oil is discharged. When the temperature is low, for example, there is a problem that the return of the control valve to the neutral position is delayed and the turning stop position is shifted, and there is a problem to be solved by the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made to solve these problems, and is a revolving body that revolves based on driving of a revolving motor. In a construction machine equipped with a working part whose working posture changes, a posture detecting means for detecting the posture of the working part is provided, and a control valve for controlling the supply of pressurized oil to the turning motor; The pilot pressure supplied from the pilot valve to the control valve in response to the detection signal from the attitude detection means is connected to a pilot oil passage connecting the pilot valve for supplying and discharging the pilot pressure oil to and from the control valve based on It is provided with a throttle means for squeezing oil and a discharge means for flowing oil from the control valve to the pilot valve without squeezing. That. By doing so, the pilot pressure oil throttled in accordance with the posture of the working unit is supplied to the control valve. The rapid acceleration of the control valve can be alleviated, the turning speed does not decrease, and the oil discharged from the control valve is not throttled. The return operation can be performed promptly. In this apparatus, a control unit for inputting a detection signal from the attitude detection unit and outputting a command based on the detection signal is provided, and the throttle unit is configured to reduce a pilot pressure oil throttle amount based on a command from the control unit. Can be configured using an electromagnetic proportional switching valve that operates to adjust the pressure. In this case, by setting the electromagnetic proportional switching valve so as to operate to reduce the pilot pressure oil when the pressure of the pilot pressure oil supplied from the pilot valve is equal to or higher than a preset pressure, the turning-on at the time of turning-on And a response delay at the time of fine operation can be avoided. Further, the discharge means can be configured by using a check valve that allows the flow of oil from the control valve to the pilot valve but blocks the flow in the reverse direction. Further, in these devices, by connecting negative pressure prevention means for supplying oil in the oil tank to the control valve without passing through the throttle means to the pilot oil path, the pilot oil path becomes negative pressure and the control valve is closed. It is possible to avoid delaying the returning operation to the neutral position. In addition, a control unit that inputs a detection signal from the attitude detection unit and outputs a command based on the detection signal is provided, and the throttle unit and the discharge unit open and close the pilot oil passage based on the command from the control unit. And a throttle valve provided in parallel with the electromagnetic switching valve and configured to throttle the pilot pressure oil in accordance with the output pressure from the pilot valve.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIGS. In FIG.
Reference numeral 1 denotes a small-rotation type hydraulic excavator. The hydraulic excavator 1 includes a crawler-type lower traveling body 2, an upper revolving body 3 that is rotatably supported by the lower traveling body 2, and mounted on the upper revolving body 3. And a boom 5 that is swingably supported by the upper revolving unit 3 and an arm 6 that is swingably supported by the tip of the boom 5. The basic configuration is the same as that of the related art, such as being constituted by members such as a bucket 7 which is swingably supported by the tip of the arm 6.

A turning motor 8 for turning the upper turning body 3 is shown in FIG. 2. A hydraulic oil supply circuit to the turning motor 8 is shown in FIG. 2. In FIG. 10 is a pilot pump, 11 is an oil tank, 12
Is a control valve, and the control valve 12 has pilot ports 12a, 1
It comprises a three-position switching valve provided with 2b. The control valve 12 is connected to both pilot ports 12
In a state in which the pilot pressure oil is not supplied to the a and 12b, the pilot pressure oil is located at the neutral position N in which the pressure oil is not supplied to the turning motor 8, but the pilot pressure oil is in the forward or reverse rotation side of the pilot port 12a or 12b. 12b, the pressure is switched to a pressure oil supply position X or Y for supplying pressure oil from the main pump 9 to the turning motor 8, whereby the turning motor 8 is configured to drive forward and reverse. I have.

Reference numeral 13 denotes the control valve 12
A brake circuit incorporated in a main oil passage connecting the motor and the turning motor 8. The brake circuit 13 includes a pair of overload relief valves 14A and 14B and check valves 15A and 15B for preventing negative pressure. The brake circuit 13 can reduce the impact and swing back when the vehicle stops turning.

On the other hand, 16A and 16B are the turning lever 1
6C is a forward-rotation-side and reverse-rotation-side pilot valve that supplies pilot pressure oil to the pilot port 12a or 12b of the control valve 12 based on the operation of 6C.
The pilot valves 16A and 16B are connected to the pump port 1
6a, a pressure control valve having a tank port 16b, and an output port 16c. The pilot ports 16A and 16B close the pump port 16a when the turning lever 16C is not operated.
The tank port 16b and the output port 16c communicate with each other. By operating the turning lever 16C, the pilot port 16A or 1A on the operated side is operated.
The pump port 16a of 6B communicates with the output port 16c, whereby a pilot pressure corresponding to the operation amount of the turning lever 16C is output from the output port 16c.

Further, the output ports 16c of the pilot valves 16A and 16B on the forward and reverse sides and the pilot ports 12 on the forward and reverse sides of the control valve 12 are provided.
a and 12b are connected to the forward and reverse rotation pilot oil passages, respectively.
A, 17B and first check valves 18A, 18B are arranged, respectively. Further, in a tank oil passage T to be described later, forward and reverse rotation second check valves 19A, 19B are arranged. Since the forward rotation side and the reverse rotation side are the same, the forward rotation side will be described as an example.

The electromagnetic proportional switching valve 17A is a two-position switching valve having a solenoid 17a.
When the excitation signal is not input to the control valve a, the pilot pressure oil output from the pilot valve 16A is located at the open position X which is supplied to the control valve pilot port 12a without being throttled. When the excitation signal is input to the solenoid 17a based on a command from the control valve, the pilot pressure oil from the pilot valve 16A is throttled to switch to the throttle position Y to be supplied to the control valve pilot port 12a. The amount of opening of the diaphragm at the diaphragm position Y is set so as to decrease as the input signal to the solenoid 17a increases.

The first check valve 18A is arranged in parallel with the electromagnetic proportional switching valve 17A.
This is the control valve pilot port 12
It is configured such that the flow of oil from a to the pilot valve 16A is allowed, but the flow in the reverse direction is blocked. Thereby, the pilot pressure oil output from the pilot valve 16A is supplied to the control valve pilot port 12a via the electromagnetic proportional switching valve 17A, while the oil discharged from the control valve pilot port 12a is supplied to the first check valve. It flows to the pilot valve 16A via 18A.

Further, a tank oil passage T connected to the oil tank 11 joins a pilot oil passage between the electromagnetic proportional switching valve 17A and the control valve pilot port 12a. A second check valve 19A is provided in the middle of the second check valve. The second check valve 19A is configured so as to block the flow of oil from the pilot oil passage to the oil tank 11, but to allow the flow in the reverse direction. , The oil from the oil tank 11 can be supplied to the pilot oil passage.

On the other hand, the control section 20 is constructed using a microcomputer or the like.
The procedure of the turning control at 0 will be described with reference to the block diagram shown in FIG. 3. First, the control unit 20 detects the swing angle of the boom 5 (α in FIG. 1, hereinafter referred to as boom angle α). A sensor 21 and a detection signal from an arm angle sensor 22 for detecting a swing angle of the arm 6 (β in FIG. 1, hereinafter referred to as an arm angle β) are input to a bucket position calculator 23. The bucket position calculator 23
The horizontal distance (reach) Xc from the turning center O to the swing fulcrum C of the bucket 7 based on the detection signals input from the boom angle sensor 21 and the arm angle sensor 22 is calculated by the following equation (1). Calculate using Xc = Lb · sin α + La · sin (α + β) (1) In the above equation (1), Lb is the boom length from the swing fulcrum A of the boom 5 to the swing fulcrum B of the arm 6, and La is the swing of the arm. The arm length from the fulcrum B to the swing fulcrum C of the bucket 7, and as described above, α is the boom angle and β is the arm angle (see FIG. 1). Since the boom 5 of the present embodiment is of an offset type capable of swinging right and left, the boom length La changes depending on the offset angle (the right and left swing angle of the boom 5), but the change is very large. Instead, the equation (1) does not consider the offset angle, but a sensor for detecting the offset angle is provided, and the equation (1) is corrected based on an input signal from the offset angle sensor. Of course, it can also be configured. Next, based on the reach Xc calculated by the bucket position calculator 23, the controller 20 sets an excitation signal for the solenoids 17a of the electromagnetic proportional changeover valves 17A and 17B by the drive signal setting unit 24, and converts the excitation signal to an electromagnetic signal. It outputs to proportional switching valves 17A and 17B. In this case, as shown in FIG. 3, when the reach Xc is longer than the preset reach D, a non-excitation signal is output, whereby the electromagnetic proportional switching valves 17A and 17B are located at the open position X. , The pilot pressure oil output from the pilot valves 16A, 16B is not throttled and the control valve 12a,
12b. On the other hand, when the reach Xc is shorter than the set reach D, an excitation signal is output, whereby the electromagnetic proportional switching valves 17A and 17B are switched to the throttle position Y, and the pilot valves 16A and 16B
The pilot pressure oil output from the controller is throttled and supplied to the control valves 12a and 12b. In this case, as the reach Xc becomes shorter, the excitation signal becomes larger, that is, the electromagnetic proportional switching valves 17A and 17B The aperture of the stop is set to be small. Here, when the reach Xc is shorter than the set reach D, the set reach D is reduced to a distance where the moment of inertia at the time of starting the turning of the upper-part turning body 3 becomes small, and rapid acceleration may be performed. Is set.

In the structure constructed as described above, the moment of inertia at the time of starting the turning of the upper turning body 3 becomes smaller as the reach Xc from the turning center O to the bucket 7 is shorter, but when the reach Xc is shorter, The electromagnetic proportional switching valves 17A, 17B are switched to the throttle position Y based on a command from the control unit 20, and the pilot valves 16A, 16B
From control valve pilot ports 12a, 12
The pilot pressure oil supplied to b will be reduced. Moreover, in this case, as the reach Xc becomes shorter, the aperture of the aperture of the electromagnetic proportional switching valves 17A, 17B becomes smaller,
The pilot pressure oil will be reduced.

As a result, when the working unit 4 is in a posture in which the moment of inertia at the time of turning start is small, the pilot pressure oil throttled corresponding to the working posture is supplied to the control valve pilot ports 12a and 12b. As a result, the switching operation from the neutral position N of the control valve 12 to the pressure oil supply position X and the pressure oil supply positions X and Y is performed gently, whereby the acceleration at the time of turning start is eased, and hunting is started. Generation and spillage of the load from the bucket 7 due to rapid acceleration can be prevented.

Further, this is a control valve 1
The pilot pressure oil supplied to the control valve 12 is not reduced by the pressure reducing valve but is adjusted by the flow rate of the throttle valve, so that the supply pressure to the control valve 12 increases to the output pressure of the pilot valves 16A and 16B. Become,
Workability can be ensured without lowering the turning speed.

Further, in this case, the oil discharged from the control valve pilot ports 12a, 12b is:
In the case where the oil flows to the pilot valves 16A and 16B via the first check valves 18A and 18B without passing through the electromagnetic proportional changeover valves 17A and 17B and the pilot oil passage becomes negative pressure, the oil from the oil tank 11 Since the oil is supplied to the pilot oil passage via the second check valves 19A and 19B, even when the operating oil is at a low temperature, the control valve 12 is quickly returned to the neutral position N. In other words, the turning lever 16 is required to stop turning.
When C is operated to the neutral position, the control valve 12
It is possible to avoid such a problem that the turning stop position is shifted due to the delay of the neutral return.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 1 shares the first embodiment. In FIG. 4, 8
Is a turning motor, 9 is a main pump, 10 is a pilot pump, 11 is an oil tank, 12 is a control valve,
13 is a brake circuit, 16A and 16B are pilot valves, 16C is a turning lever, 17A and 17B are electromagnetic proportional switching valves, 18A and 18B are first check valves, 19A and 1B.
9B is a second check valve, 21 is a boom angle sensor, and 22 is an arm angle sensor. These are the same as those in the first embodiment, and the description is omitted. In the form of the pilot valve 16A,
A pressure sensor 25 for detecting the pilot pressure output from 16B is provided.

The pressure sensor 25 detects the output pressure from the forward rotation side pilot valve 16A and the reverse rotation side pilot valve 1A.
6B is connected to the output port of the shuttle valve 26 that selects the high pressure side from the output pressure from the 6B. When pilot pressure oil is output from the forward rotation side or reverse rotation side pilot valve 16A or 16B, the pilot pressure oil is selected by the shuttle valve 26 and the pressure is detected by the pressure sensor 2.
5, the detection signal of the pressure sensor 25 is configured to be input to the control unit 27.

Next, the control unit 2 in the second embodiment
The control procedure of FIG. 7 will be described with reference to the block diagram shown in FIG. 5. The control unit 27 receives input from the boom angle sensor 21 and the arm angle sensor 22 in the same manner as in the first embodiment. The reach Xc from the turning center O to the bucket 7 is calculated by the bucket position calculator 23 based on the detection signal, and based on the calculated reach Xc, the drive signal setting unit 24 sets the electromagnetic proportional switching valve 17A,
Set the excitation signal for 17B. Further, in the second embodiment, the excitation signal set by the drive signal setter 24 is output to the signal selector 28. On the other hand, the control unit 27 outputs the detection signal from the pressure sensor 25 to ON-
The signal is input to the OFF signal setting device 29. And the ON-OF
The F signal setting unit 29 outputs an OFF signal when the detection signal of the pressure sensor 25 is lower than the preset pressure E, and turns ON when the detection signal of the pressure sensor 25 is higher than the preset pressure E. Is output to the signal selector 28. Reference numeral 30 denotes a minimum signal setter, which outputs a non-excited signal to the electromagnetic proportional changeover valves 17A and 17B to the signal selector 28. Then, the signal selector 28 outputs an O-OFF signal from the ON-OFF signal
When the FF signal is input, the minimum signal setting unit 30
Is output to the electromagnetic proportional changeover valves 17A and 17B, and when an ON signal is input from the ON-OFF signal setting device 29, the excitation signal input from the drive signal setting device 24 is It outputs to proportional switching valves 17A and 17B. That is, when the output pressures of the pilot valves 16A and 16B are lower than the set pressure E, the electromagnetic proportional switching valve 17
A non-excitation signal is output to A and 17B, whereby the pilot pressure oil output from pilot valves 16A and 16B is supplied to control valve pilot ports 12a and 12b without being throttled. On the other hand, when the output pressures of the pilot valves 16A and 16B are equal to or higher than the set pressure E, when the reach Xc is longer than the set reach D, a non-excited signal is output to the electromagnetic proportional switching valves 17A and 17B. When Xc is shorter than the set reach D, an excitation signal is output to the electromagnetic proportional switching valves 17A and 17B so as to reduce the pilot pressure oil as the reach Xc becomes shorter.

The second embodiment also has the same operation and effect as those of the first embodiment, but further has a pilot valve 16A,
When the output pressure of 16B is lower than the set pressure E, the pilot pressure oil is not throttled regardless of the working posture, so that a response delay at the time of turning start or fine operation can be avoided, and operability is improved. I do.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 1 shares the first embodiment. In FIG. 6, 8 is a turning motor, 9 is a main pump, 10 is a pilot pump, 11 is an oil tank, 12 is a control valve, 13
Is a brake circuit, 16A and 16B are pilot valves,
Reference numeral 16C denotes a turning lever, 21 denotes a boom angle sensor, and 22 denotes an arm angle sensor. These are the same as those in the first embodiment, and thus description thereof will be omitted.

Further, in the third embodiment, the forward and reverse rotation pilot oil passages connecting the pilot valves 16A and 16B and the control valve pilot ports 12a and 12b are connected to the forward rotation and reverse rotation, respectively. The electromagnetic switching valves 31A and 31B and the pilot-type throttle valves 32A and 32B are arranged, respectively. However, since the forward rotation side and the reverse rotation side are the same, the forward rotation side will be described as an example. .

The solenoid-operated switching valve 31A includes a solenoid 31
a two-position switching valve provided with the pilot valve 16A when the solenoid 31a is not excited.
Is located at an open position X for opening a pilot oil passage from the control valve to the control valve pilot port 12a, but is turned to a closed position Y for closing the pilot oil passage when the solenoid 31a is excited based on a command from the control unit 33. It is configured to switch.

The pilot-type throttle valve 32A is disposed in parallel with the electromagnetic switching valve 31A. This is a two-position throttle valve having a pilot port 32a connected to the output side of the pilot valve 16A. When the pilot pressure oil output from the pilot valve 16A is lower than the set pressure E (the set pressure E is set in the same manner as the set pressure E of the second embodiment), Is located at a communication position X where the pilot valve 16A and the control valve pilot port 12a communicate with each other without being throttled. If the pressure of the pilot pressure oil output from the pilot valve 16A is equal to or higher than the set pressure E, It is configured to switch to a throttle position Y where throttled pilot pressure oil is throttled and output to the control valve pilot port 12a. In this case, the opening degree of the throttle is set to be smaller as the output pressure of the pilot valve 16A becomes higher.

On the other hand, the control unit 33 of the third embodiment
Based on the detection signals input from the boom angle sensor 21 and the arm angle sensor 22, the reach Xc from the turning center O to the swing fulcrum C of the bucket 7 is calculated in the same manner as in the first embodiment. . When the reach Xc is longer than the set reach D (the set reach D is set in the same manner as the set reach D of the first and second embodiments), the electromagnetic switching valve 31A, A non-excitation signal is output to 31B. Thereby, the electromagnetic switching valves 31A, 3
1B is located at the open position X, and the pilot valve 16A,
The pilot pressure oil output from 16B is in the open position X
Are supplied to the pilot valves 16A and 16B control valve pilot ports 12a and 12b via the electromagnetic switching valves 31A and 31B. On the other hand, when the reach Xc is shorter than the set reach D, the electromagnetic switching valves 31A, 31B
An excitation signal is output to the electromagnetic switching valve 31
A and 31B are switched to the closed position Y. When the electromagnetic switching valves 31A and 31B are in the closed position Y, the pilot pressure oil output from the pilot valves 16A and 16B passes through the pilot-type throttle valves 32A and 32B to control valve pilot ports 12a and 12B.
b.

Also in the third embodiment, when the reach Xc from the turning center O to the bucket 7 is short, that is, when the working unit 4 is in a posture in which the moment of inertia at the time of turning start is small. The pilot pressure oil throttled by the pilot type throttle valves 32A and 32B is supplied to the control valve pilot ports 12a and 12b, so that the acceleration at the time of turning start is moderated, and hunting occurs and rapid acceleration occurs. The spillage of the load from the bucket 7 can be prevented, and the reduction of the turning speed can be avoided.

Further, the pilot type throttle valve 32A,
32B, when the output pressure of the pilot valves 16A and 16B is lower than the set pressure E, the pilot pressure oil is not restricted,
When the output pressure is equal to or higher than the set pressure E, the pilot pressure oil is reduced and supplied to the control valve pilot port 12a as the output pressure increases.
A response delay at the time of turning start or a fine operation can be avoided, and a sudden acceleration when the turning lever 16C is suddenly operated can be avoided, thereby improving operability.

In this case, when the output pressure of the pilot valve 16A falls below the set pressure E, the oil discharged from the control valve pilot ports 12a, 12b is throttled through the pilot type throttle valves 32A, 32B at the communication position X. Pilot valves 16A, 16
B, the control valve 12 is quickly returned to the neutral position N even when the temperature of the oil is low, and when the turning lever 16C is operated to the neutral position to stop turning. It is possible to avoid such a problem that the turning stop position is shifted due to a delay in the return of the control valve 12 to the neutral position.

[Brief description of the drawings]

FIG. 1 is a side view of a hydraulic excavator.

FIG. 2 is a hydraulic circuit diagram according to the first embodiment.

FIG. 3 is a control block diagram according to the first embodiment.

FIG. 4 is a hydraulic circuit diagram according to a second embodiment.

FIG. 5 is a control block diagram according to a second embodiment.

FIG. 6 is a hydraulic circuit diagram according to a third embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 upper revolving unit 4 working unit 8 turning motor 12 control valve 16A pilot valve 16B pilot valve 16C turning lever 17A electromagnetic proportional switching valve 17B electromagnetic proportional switching valve 18A first check valve 18B first check valve 19A second check valve 19B Second check valve 20 Control unit 21 Boom angle sensor 22 Arm angle sensor 25 Pressure sensor 27 Control unit 31A Electromagnetic switching valve 31B Electromagnetic switching valve 32A Pilot-type throttle valve 32B Pilot-type throttle valve 33 Control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuaki Matoba 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Within Sanishi Heavy Industries Co., Ltd. No. Takashi Engineering Co., Ltd. F-term (reference) 2D003 AA01 AB02 AB03 BA01 BA02 BB10 CA03 DA03 DA04 DB02 DB04 FA02 3H089 AA32 AA61 BB14 BB15 BB21 CC08 DA02 DB03 DB33 DB47 DB49 EE13 EE16 EE18 EE22 EE35 FF03 FF12 GG02

Claims (6)

[Claims] 1. A construction machine in which a working unit having a changing working posture is mounted on a revolving body that rotates based on driving of a turning motor, wherein a posture detecting means for detecting a posture of the working unit is provided. A control valve for controlling the supply of pressurized oil of the turning motor and a pilot oil passage for connecting a pilot valve for supplying and discharging pilot pressure oil to and from the control valve based on operation of the operating tool are connected to the pilot oil passage. Turning control in a construction machine provided with a throttling means for throttling the pilot pressure oil supplied from the pilot valve to the control valve in response to the detection signal, and a discharge means for flowing the oil from the control valve to the pilot valve without being throttled. apparatus. 2. A control device according to claim 1, further comprising a control unit for inputting a detection signal from the posture detection unit and outputting a command based on the detection signal, and the diaphragm unit based on the command from the control unit. A turning control device for a construction machine, which is an electromagnetic proportional switching valve that operates to adjust the throttle amount of pilot pressure oil. 3. The electromagnetic proportional switching valve according to claim 2,
A turning control device for a construction machine which is set to operate to reduce the pilot pressure oil when the pressure of the pilot pressure oil supplied from the pilot valve is equal to or higher than a preset pressure. 4. The swing control device according to claim 1, 2 or 3, wherein the discharge means has a check valve that allows a flow of oil from the control valve to the pilot valve, but prevents a flow in the reverse direction. . 5. The turning control in a construction machine according to claim 1, wherein the pilot oil passage is connected to a negative pressure prevention means for supplying oil in an oil tank to a control valve without passing through a throttle means. apparatus. 6. The control device according to claim 1, further comprising: a control unit that receives a detection signal from the posture detection unit and outputs a command based on the detection signal.
An electromagnetic switching valve that opens and closes a pilot oil passage based on a command from the control unit; and a throttle valve that is provided in parallel with the electromagnetic switching valve and throttles pilot pressure oil in accordance with the output pressure from the pilot valve. A turning control device for a construction machine that is configured by using a computer.