JP2549420B2 - Swing control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a turning control device in a construction machine such as a hydraulic excavator or a hydraulic crane.

[Conventional technology]

2. Description of the Related Art Conventionally, in a swing control device for a hydraulic crane, in order to smoothly perform a swing, a swing is performed by a secondary pressure from a remote control valve (hereinafter referred to as a remote control valve) as disclosed in Japanese Patent Laid-Open No. 53-21379, for example. It is known to control the set pressure of a pilot type variable relief valve provided between both side circuits of a hydraulic motor.

[Problems to be Solved by the Invention]

In the above conventional device, the secondary pressure from the remote control valve, which is output according to the operation amount of the lever, switches the directional control valve and controls the set pressure of the variable relief valve on the inflow side of the motor to accelerate the motor. Although it controls the pressure, the directional control valve is a neutral all-port open, and when the lever is returned to the neutral position, the circuits on both sides of the motor are in communication with each other and the set pressures of both variable relief valves are both set. Since the motor is rotated by inertia due to a low pressure, which is a so-called neutral free system, the motor cannot be stopped at the lever neutral. When the motor decelerates and stops, after returning the lever to neutral, the so-called reverse lever is operated in the direction opposite to the motor rotation direction, and the set pressure of the variable relief valve on the motor discharge side is set to the value when accelerating according to the reverse lever operation amount. The deceleration pressure of the motor is controlled by controlling with the same control pattern.

By the way, the turning control system includes a neutral brake that stops the rotation of the motor when the lever is returned to neutral, in addition to the neutral free system that rotates the motor by inertia when returning the lever to neutral. There are methods, and there are cases where the neutral free method is better and cases where the neutral brake method is better depending on the work content and the like. Therefore, it is desirable to allow one machine to arbitrarily select one of the methods.

However, the above conventional control device uses a neutral all-port open directional valve, and since the set pressure of the variable relief valve is controlled by the same control pattern during acceleration and during deceleration by the reverse lever, the neutral free valve is used. Applicable only to the system, not the neutral brake system.

The present invention has been made to solve such a problem, and one machine can arbitrarily select the neutral free mode and the neutral brake mode according to the work content and the like.
It is another object of the present invention to provide a swing control device capable of appropriately controlling the acceleration pressure and the deceleration pressure of the motor according to each mode.

[Means for solving the problem]

According to a first aspect of the present invention, in a swing control device in which a directional control valve for controlling a rotation direction of the motor is provided between the hydraulic pump and the slewing hydraulic motor, the directional control valve has a bleed-off passage of a neutral PR connection. A pressure control valve is connected to a pipe line connecting both side ports of the swing hydraulic motor and the direction switching valve, and a rotation direction detecting means for detecting a rotation direction of the swing hydraulic motor; Based on signals from the switching amount detecting means for detecting the switching amount of the switching valve, the mode selecting means for selecting the neutral brake mode and the neutral free mode, and the signals from the rotation direction detecting means, the switching amount detecting means and the mode selecting means. A controller for controlling the pressure control valve, the controller including detection signals from the rotation direction detection means and the switching amount detection means, and the mode selection. The operating state of the motor is determined based on the mode selection signal from the means. (A) In the neutral brake mode, I. When the directional control valve is neutral, the set pressure of the pressure control valve is set to high pressure, and II. During acceleration, the greater the valve switching amount from the neutral position of the directional control valve to the turning position side, the higher the set pressure of the pressure control valve on the motor inflow side, and III. The control signal that raises the set pressure of the pressure control valve on the motor discharge side is output. (B) In the neutral free mode, i. When the directional control valve is neutral, the set pressure of the pressure control valve is set to a low pressure. Ii. During turning acceleration, the larger the switching amount of the directional control valve, the higher the set pressure of the pressure control valve on the motor inflow side, and iii. During turning deceleration, the direction opposite to the motor rotation direction of the directional control valve. The larger the switching amount to It is configured to output a control signal for increasing the set pressure of the pressure control valve.

According to a second aspect of the present invention, in the configuration of the first aspect, the pressure control valve is connected to a pipe line connecting both side ports of the swing hydraulic motor and the direction switching valve, and a variable relief valve master valve and a pressure of the master valve. And a common slave valve composed of an electromagnetic proportional pressure control valve connected to the control unit, and the controller detects the detection signals from the rotation direction detecting means and the switching amount detecting means,
The operation state of the motor is determined based on the mode selection signal from the mode selection means. (A) In the neutral brake mode, I. When the directional control valve is neutral, the set pressure of the slave valve is set to a high pressure, II. During swing acceleration, the larger the switching amount from the neutral position of the directional control valve to the swing position side, the higher the set pressure of the slave valve, and III. The smaller the switching amount of the directional switching valve during deceleration of the swing, the smaller the slave valve. The control signal is output to increase the setting pressure in (B) in the neutral free mode. I. When the directional control valve is neutral, the set pressure of the slave valve is set to a low pressure, and ii. The control valve outputs a control signal that increases the set pressure of the slave valve as the switch amount increases, and iii. Decreases the set pressure of the slave valve as the switch amount of the directional control valve decreases during turning deceleration. It was done.

[Action]

With the above configuration, one machine can arbitrarily select the neutral free mode and the neutral brake mode according to the work content and the like, and can appropriately control the acceleration pressure and deceleration pressure of the motor according to each mode. become.

〔Example〕

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention, in which 1 is a hydraulic pump, 2 is a main relief valve, 3 is a direction switching valve, 4 is a swing hydraulic motor, and 5 is a motor 4. 2 shows an upper revolving structure of a construction machine that is rotationally driven by. The direction switching valve 3 is a three-position switching valve having a bleed-off passage of neutral PR connection, and switching of this valve 3 controls supply and discharge of pressure oil to both side circuits 6 and 7 of the motor 4,
The rotation of the motor 4 is controlled. 8 and 9 are cavitation prevention check valves, and 10 is a tank.

In this hydraulic circuit, circuits 6 and 7 between both side ports of the motor 4 and the directional control valve 3 are connected with electromagnetic proportional relief valves (or electromagnetic proportional pressure reducing valves) 11 and 12 as electromagnetic proportional pressure control valves, respectively. There is. The direction switching valve 3 is provided with a sensor 13 for detecting a spool stroke (or a lever operating angle) as a switching amount detecting means for the motor 4
A rotation direction sensor 14 is attached to the. Reference numeral 15 is a mode selection means for selecting the neutral brake mode or the neutral free mode. The controller 16 outputs a set pressure control signal to the electromagnetic proportional relief valves 11 and 12 based on the selection signal from the mode selection means 15 and the detection signals from the sensors 13 and 14.

 Next, turning control will be described.

I-Neutral brake mode First, when the neutral brake mode is selected by the mode selection means 15 and the operation lever is operated to the push side to switch the direction switching valve 3 to the push side (right side in the figure), the discharge of the pump 1 is performed. Oil is supplied to the motor 4 via the circuit 6, the pressure in the circuit 6 rises, the motor 4 is accelerated in the normal rotation, the revolving unit 5 is swiveled to the right, and the oil discharged from the motor 4 is rotated in the circuit 7 and the direction. It is returned to the tank 10 via the switching valve 3.

During this turning acceleration, the spool stroke of the direction switching valve 3 is detected by the sensor 13 and the rotation direction (normal rotation) of the motor 4 is detected by the sensor 14, and these detection signals and the selection signal by the selection means 15 are detected. Are input to the controller 16, and the control shown in the flowchart of FIG. 2 is performed.

That is, in FIG. 2, when the program starts, the value detected by the stroke sensor 13 is read in step S ₁ , and the rotation direction (normal rotation) of the motor 4 detected by the rotation direction sensor 14 is read in step S ₂ . In step S ₃ , it is determined whether the spool of the directional control valve 3 is neutral. At this time, the spool is on the push side, so step S ₃
In "NO", "YES" next in step S _4, "YES" becomes the motor 5 in step S ₅ is positive conversion, further, "YES" next in either neutral brake mode in step S _6, in step S ₇ move on. Then, the control signal of the acceleration pattern shown by the solid line A in FIG. 3 is output to the relief valve 11 on the inflow side of the motor 4, and the control signal of the deceleration pattern shown by the solid line B on the same is output to the relief valve 12 on the motor discharge side. Is output, and the set pressure of the relief valve 11 is changed from a low pressure to a high pressure (for example, 30 to 30) according to the acceleration pattern according to the spool stroke of the directional control valve 3.
190kg / cm ² ) and the relief valve 1
The set pressure of ² is controlled in the range of high pressure to low pressure (for example, 190 to 30 kg / cm ² ) along the deceleration pattern.

In this case, the directional control valve 3 has a bleed-off passage,
By bleeding off the entire discharge flow rate of the pump 1 to the tank 10 in the neutral state, gradually increasing the inflow rate into the circuit 6 while reducing the bleed-off flow rate from the pump 1 to the tank 10 as the spool stroke increases. The pressure that is uniquely determined by the flow rate control of the directional control valve 3 is neutral and is 0. Although it slightly varies depending on the pump discharge flow rate, it is generally controlled by a gentle curve in a low pressure range in a small spool stroke range and a steep curve in a large spool stroke range. It becomes a high pressure in the curve. Therefore, if the pressure (acceleration pressure) on the inflow side of the motor 4 is controlled only by controlling the flow rate by the direction switching valve 3, the controllability in the low pressure range is good, but the controllability in the high pressure range becomes poor.

However, by controlling as described above, the acceleration pressure of the motor 4 is controlled by the pressure determined by the flow rate control of the directional control valve 3 and the pressure on the low pressure side of the set pressure of the relief valve 11. In the range where the spool stroke is small (low pressure range), the flow rate control (pressure control) of the directional control valve 3 is prioritized, and in the range where the spool stroke is large (high pressure range), the control by the set pressure of the relief valve 11 is prioritized. Is smoothly controlled, the controllability is greatly improved, and the motor 4 is smoothly accelerated.

After that, when the directional control valve 3 is returned to the neutral direction, the area of the passage opening from the motor 4 of the directional control valve 3 to the tank 10 is narrowed, while the motor 4 rotates forward due to inertia, so The pressure of the circuit 7 gradually increases, and the motor 4 is decelerated by the pressure (deceleration pressure). At this time, the spool stroke is still on the pushing side during the return operation of the directional control valve 3 (“YES” in step S ₄ ) and the motor 4 is normally rotating due to inertia (“YES” in step S ₅ ).
Set pressure of the step S ₁ to S ₇ the motor 4 the discharge side of the relief valve 12 of the is controlled along the deceleration pattern (Fig. 3 the solid line B), as the return direction switching valve 3 in its neutral by this control, The deceleration pressure of the motor 4 gradually increases and the motor 4
Is efficiently decelerated.

It should be noted that, even when the lever is pushed and pulled from the neutral side at the time of accelerating and decelerating the above-mentioned turning, as long as the lever is on the pushing side and the motor 4 is normally rotating,
The relief valve 11 on the motor inflow side is controlled in accordance with the acceleration pattern (solid line B above), and the relief valve 12 on the motor discharge side is controlled in accordance with the deceleration pattern (solid line B above). Is properly controlled according to the spool stroke, and acceleration and deceleration are performed smoothly.

When the directional control valve 3 is stopped at the neutral position after the turning deceleration, the supply of pressure oil from the pump 1 to the motor 4 is stopped, and the oil discharged from the motor 4 to the tank 10 is also blocked.
The pressure in the circuit 7 on the motor discharge side rises sharply. At this time in Step S ₃ "YES", and the addition, the flow proceeds to step S ₉ becomes "YES" in the step S ₈ because it is a neutral brake mode. The set pressure of the relief valve 12 on the motor discharge side is controlled to a high pressure (for example, 190 kg / cm ² ), and the set pressure of the relief valve 11 on the motor inflow side is also high (for example, 190 kg / cm ² ). And the motor 4 is braked at a high pressure.

Further, when the directional control valve 3 is operated from the push side to the neutral side and the reverse lever is operated at the time of decelerating and stopping the turning, the discharge oil of the pump 1 flows into the circuit 7 on the discharge side of the motor 4 and flows in. The side circuit 6 is connected to the tank 10. At this time "NO" is determined in the step S _4, also, since the motor 4 against the directional control valve 3 is operated in the pulling side is rotated forward by inertia, "NO" is determined in the step S _10, further neutral "YES" is determined in the step S ₁₁ since it is braking mode, the process proceeds to step S _12. Then, while keeping the set pressure of the relief valve 12 on the motor discharge side at high pressure (dashed line c above).
Thus, the set pressure of the relief valve 11 on the motor inflow side is controlled so as to gradually become lower along the deceleration pattern (solid line D above). As a result, even if the reverse lever is operated, the deceleration pressure does not decrease and remains at a high pressure, and the oil discharged from the motor 4 and the pressure oil from the pump 1 flow into the circuit 7, and the motor 4 quickly Is braked.

In this neutral brake mode, when the directional control valve 3 is neutral, the set pressures of both the relief valves 11 and 12 are controlled to be high, whereas the setting of the relief valve 11 on the motor inflow side is set at the time of turning acceleration. The control is started from a low pressure, but the control by the directional control valve 3 is prioritized in the range where the spool stroke is small in the initial stage of the control, and the relief valve is operated in the range where the spool stroke is large.
Since the control by 11 is prioritized, there is no risk of hunting or the like, and there is no risk of interfering with turning control.

If the directional control valve 3 is held in the neutral position after the motor 4 is braked, both circuits 6 and 7 will be blocked and the steps S ₁ → S ₂ → S ₃ → S ₄ → S _{8 will be performed.} since → set pressure of both the relief valves 11 and 12 by S ₉ are both held in a high pressure, the stop state of the motor 4 is reliably held, there is no possibility that the upper rotating body 5 to freely pivot by the wind pressure or the like. In addition, even on a sloping ground, there is no possibility that the upper-part turning body 5 will turn in the downhill direction, and safety is improved.

In the neutral brake mode, when the directional control valve 3 is switched to the pulling side, the discharge oil of the pump flows into the motor 4 via the circuit 7, the motor 4 is rotated in the reverse direction, and the revolving structure 5 is swung leftward. The oil discharged from the motor 4 is returned to the tank 10 via the circuit 6 and the direction switching valve 3. During this swing acceleration and deceleration, the relief valve 12 is on the motor inflow side and the relief valve 11 is on the motor exhaust side, and steps S ₁ → S ₂ → S ₃ → S ₄ → S ₁₀ → S ₁₃ → S _{14 in} the flowchart of FIG. And proceed,
While the set pressure of the relief valve 12 on the motor inflow side is controlled along the acceleration pattern (solid line E above), the set pressure of the relief valve 11 on the motor discharge side is controlled along the deceleration pattern (solid line D above). Thereafter, the motor 4 is smoothly accelerated and decelerated by the same operation as described above.

After that, if the directional control valve 3 is returned to neutral, step S ₃ →
Proceeds S ₈ → S _9, the set pressure of both the relief valves 11 and 12 are both becomes high, turning body 5 is securely held in neutral. If the reverse lever is operated, step S ₄ → S ₅ → S ₁₅ → S
_{The procedure} proceeds to ₁₆ and the set pressure of the relief valve 11 on the motor discharge side is maintained at high pressure (dashed line to the same as above), while the set pressure of the relief valve 12 on the motor inflow side is controlled according to the deceleration pattern (solid line B above). The deceleration of the turning is stopped promptly.

I-neutral free mode The neutral free mode is selected by the mode selection means 15,
Operate the operating lever of the directional control valve 3 to the push side to move the motor 4
Is rotated forward and when swiveling the turning body 5 in the right direction, the step S ₁ is ~S to ₆ is processed in the same manner as in the turning acceleration in neutral brake mode of the I-, "NO in step S ₆ "
Next, the process proceeds to step S _17. Then, while the set pressure of the relief valve 11 on the motor inflow side is controlled along the acceleration pattern (the solid line a in the above), the relief valve on the motor discharge side is controlled.
The set pressure of 12 is kept low (dashed line G).
Therefore, the acceleration pressure of the motor 4 is determined by the pressure on the low pressure side of the pressure controlled by the flow rate control of the directional control valve 3 and the set pressure of the relief valve 11 as in the case of I-, and the spool In the range where the stroke is small (low pressure range), the flow rate control (pressure control) by the directional control valve 3 is prioritized, and in the range where the spool stroke is large (high pressure range), the control is prioritized by the set pressure of the relief valve 11, and the motor 4 is smooth. Be accelerated to.

However, in the neutral free mode, as long as the directional control valve 3 is on the push side, the set pressure of the relief valve 12 on the deceleration side remains low pressure (broken line G above), so the directional control valve 3 is returned to the neutral direction. Even when operated, the deceleration pressure is low, and the large braking force as in the neutral brake mode does not act.

Then, when returning the directional control valve 3 to the neutral, although both sides circuits 6 and 7 of the motor 6 is blocked by the directional control valve 3, "YES" in the step S ₃ this time, a "NO" in the step S ₈ Then, the process proceeds to step S ₁₈ , and the set pressures of the relief valves 11 and 12 on both sides are controlled to be low pressure (for example, 30 kg / cm ² ). Therefore, while the oil discharged from the motor 4 is relieved to the tank 10 at a low pressure via the relief valve 12 and the oil is introduced from the tank 10 to the inflow side of the motor 4 via the check valve 8, the motor 4 has inertia. Will continue to rotate.
Therefore, the so-called turning flow operation can be performed with the lever being neutral.

When the directional control valve 3 is operated from the pushing side over the neutral position to the pulling side after the turning is accelerated, the discharge oil of the pump 1 flows into the circuit 7 on the discharge side of the motor 4, and the circuit 6 on the inflow side changes. It communicates with the tank 10. At this time "NO" is determined in the step S _4, also, since the motor 4 against the directional control valve 3 is operated in the pulling side is rotated forward by inertia, "NO" is determined in the step S _10, further neutral is judged "NO" in the step S ₁₁ proceeds to step S ₁₉ since it is free mode. Then, while the set pressure of the relief valve 11 on the motor inflow side is maintained at a low pressure (broken line H in the same line), the set pressure of the relief valve 12 on the motor discharge side accelerates pattern (solid line E in the same line).
It will be controlled to gradually increase along. This controls the deceleration pressure according to the operation amount of the reverse lever operation,
The motor 4 is smoothly decelerated.

In the neutral free mode, when the direction switching valve 3 is switched to the pulling side and the motor 4 is reversely rotated to accelerate the revolving structure 5 to the left, and after the acceleration, the direction switching valve 3 is reversed from the neutral side to the pushing side by the reverse lever. The same control as above is performed when the operation is performed to decelerate and stop.

FIG. 4 is a hydraulic circuit diagram showing a second embodiment of the present invention. In this embodiment, the circuits 6 and 7 between both side ports of the motor 4 and the directional control valve 3 are provided with variable relief valve master valves 17, respectively. 18
Is connected, and a common child valve 21 composed of an electromagnetic proportional relief valve is connected to the control section of each parent valve via check valves 19 and 20, and the child valve 21 is controlled by a controller 22. The other structure is substantially the same as that of the embodiment shown in FIG. 1, and therefore, the same parts are designated by the same reference numerals.

Next, turning control according to the embodiment shown in FIG. 4 will be described.

II-Neutral Brake Mode First, when the neutral brake mode is selected by the mode selection means 15, the direction switching valve 3 is switched to the push side to rotate the motor 4 in the forward direction and the revolving structure 5 is swung to the right, FIG. Similar to the embodiment described above, the signals from the sensors 13 and 14 and the signal from the selection means 15 are input to the controller 22. Then, the controller 22 performs the control shown in the flowchart of FIG.

That is, in FIG. 5, the detection value by the stroke sensor 13 is stored in step S _20, the difference between the detected value and the stored value of the stroke sensor 13 in step S ₂₁ is calculated by the rotational direction sensor 14 in step S ₂₂ The detected rotation direction (normal rotation) of the motor 4 is read, and step S
Is determined "YES" in either ₂₃ neutral brake mode, in step S _24, the spool of the directional control valve 3 based on the calculated value in step S ₂₁ whether the acceleration state is determined. Here, the accelerating state means an operating state in which the spool of the directional control valve 3 moves away from the neutral position regardless of whether the spool is on the pushing side or the pulling side. The reverse the deceleration state (step S _27), the side pushing the spool of the directional control valve 3, In any pulling side, spool refers to the operation state of going back to the neutral position.

Thus, "in the step S ₂₄ at the time of the turning acceleration YE
The reverse lever of S "and step S ₂₅ turns to" NO "and the step
Go to S ₂₆ . Then, the control signal of the acceleration pattern shown by the solid line A in FIG. 3 (however, the solid line E when the directional control valve 3 is switched to the pulling side to accelerate) is output to the slave valve 21, and the slave valve
The set pressure of 21 is controlled in the range of low pressure to high pressure (for example, 30 to 190 kg / cm ² ) according to the spool stroke of the directional control valve 3. In this case, since the child valve 21 is common to the parent valves 17 and 18, the variable relief valve parent valve on the inflow side of the motor 4 is used.
The set pressure of 17 and the set pressure of the relief valve master valve 18 on the discharge side are always controlled to be equal.

Thus, at the time of turning acceleration, the acceleration pressure of the motor 4 is determined by the pressure on the low pressure side of the pressure determined by the flow rate control of the direction switching valve 3 and the set pressure of the variable relief valve master valve 17 controlled by the slave valve 21. The motor 4 is controlled and the motor 4 is smoothly accelerated as in the case of I- in the first embodiment.

However, this second embodiment, when returning the directional control valve 3 to the neutral direction, "NO" next in step S _24, step S ₂₇
Spool "YES" next in or deceleration state also,, "NO" next on whether reverse lever step S _28, the process proceeds to step S _29. Then, the control signal of the deceleration pattern shown by the solid line B in FIG. 3 (however, the solid line D when the directional control valve 3 is switched to the pulling side to accelerate) is output to the child valve 21, and the set pressure of the child valve 21, that is, The set pressures of the parent valves 17 and 18 are controlled so as to become higher as the directional control valve 3 is returned to the neutral position, and the deceleration pressure of the motor 4 is controlled by the relief valve master valve 18 on the motor discharge side to efficiently drive the motor 4. Be slowed down.

As described above, in the second embodiment, when accelerating the motor 4 in the neutral brake mode, the set pressure of the slave valve 21 is controlled according to the acceleration pattern (the solid line a or the same as above), and the motor 4 is decelerated. By controlling the set pressure of the child valve 21 along the deceleration pattern (the solid line B or D in the above), acceleration and deceleration of the motor 4 can be smoothly performed. In this case, the motor inflow side and the motor discharge side are controlled equally, but only one pressure is required for the acceleration and deceleration control, and therefore, there is no risk of impeding the turning control.

Also, when stopped at the neutral position direction switching valve 3 after the turning speed reducer, together with both sides circuits 6 and 7 of the motor 4 is blocked, "NO" in step S _24, in step S ₂₇ "N
O ", the spool in step S ₃₀ becomes neutral and becomes" YES ", and the process proceeds to step S _31. Then, a high pressure control signal is output to the slave valve 21, and the set pressure of the slave valve 21, that is, both relief valves. The set pressure of the master valves 17 and 18 is high (for example, 190 kg / c
m ² ), the motor 4 is braked by high pressure, and the stopped state of the motor 4 is reliably maintained.

In addition, when decelerating or stopping the turning, when the reverse lever is operated from the push side to the pull side beyond the neutral position,
Since the operation will be the acceleration state to the pull side, step S
It becomes “YES” at ₂₄ . However, since it is the reverse lever operation, “YES” is determined in the step S ₂₅ , the process proceeds to a step S ₃₁ , and the slave valve 21
Is followed by a high-voltage control signal (same as above dashed line c or f)
Is output, and the set pressures of the both relief valve master valves 17 and 18 are maintained at high pressure. Therefore, even if the reverse lever is operated, the deceleration pressure does not decrease, and the motor 4
Is quickly braked.

II-neutral free mode Select the neutral free mode by the mode selection means 15,
The direction switching valve 3 is switched to the push side to rotate the motor 4 forward,
When turning the revolving unit 5 to the right, perform the above step S
"NO" next in either ₂₃ neutral brake mode, the step S ₂₆
Then, the set pressures of the relief valve parent valves 17 and 18 are controlled via the child valve 21 along the acceleration pattern (the solid line a or the same as above). In this case, since the set pressure is always controlled in accordance with the acceleration pattern (solid line a or e in the above), the turning is smoothly accelerated by the same action as in the case of II-neutral brake mode during acceleration. When the directional control valve 3 is returned to the neutral position side after turning acceleration, the above set pressure becomes lower as it approaches the neutral position and becomes the lowest (for example, 30 kg / cm ² ) at the neutral position. A swirling flow operation becomes possible.

After that, when the reverse lever is operated from the pushing side to the pulling side over the neutral side from the pushing side, the set pressure is controlled according to the acceleration pattern, and the relief amount increases as the operation amount (spool stroke) of the reverse lever increases. The valve set pressure increases, and the pressure causes the motor 4 to decelerate and stop.

When the direction switching valve 3 is switched to the pulling side to accelerate the turn, the same control as above is performed when the direction switching valve 3 is returned to neutral and the reverse lever is operated to the pushing side.

In each of the above embodiments, the relationship between the spool stroke of the directional control valve 3 and the relief valve set pressure is not limited to the example shown in FIG. 3, but may be arbitrarily set as desired.
Further, the setting can be easily changed.

〔The invention's effect〕

As described above, according to the present invention, the work mode is selected by the mode selecting means according to the work content and the like.
The machine can freely use the neutral brake mode, which automatically stops the motor when the lever is returned to neutral, and the neutral free mode, which rotates the motor by inertia when the lever is returned to neutral. The versatility of can be improved. Further, the acceleration pressure and deceleration pressure of the motor can be automatically and properly controlled according to each mode, both acceleration and deceleration of turning can be smoothly performed, and controllability and workability can be improved.

In addition, a small capacity solenoid proportional relief valve can be used by controlling the relief valve set pressure using a common slave valve,
The structure can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing the first embodiment of the present invention, FIG. 2 is a control flowchart of the first embodiment, and FIG. 3 is a control characteristic diagram showing the relationship between spool stroke and relief valve set pressure. FIG. 4 is a hydraulic circuit diagram showing the second embodiment, and FIG. 5 is a flow chart of control of the second embodiment. 1 ... hydraulic pump, 3 ... direction switching valve, 4 ... swing hydraulic motor, 5 ... upper body, 6,7 ... circuit, 10 ... tank, 11,12 ... electromagnetic proportional relief valve (electromagnetic Proportional pressure control valve), 13 ... Spool stroke sensor, 14 ... Rotation direction sensor, 15 ... Mode selection means, 16 ... Controller, 17,18 ... Variable relief valve master valve, 21 ... Child valve (electromagnetic) Proportional relief valve), 22 ... Controller.

Claims (2)

(57) [Claims] 1. A slewing control device comprising a directional control valve for controlling a rotation direction of a motor between a hydraulic pump and a slewing hydraulic motor, wherein the directional control valve has a bleed-off passage connected to a neutral PR. A pressure control valve is connected to a line connecting both side ports of the swing hydraulic motor and the direction switching valve, and a rotation direction detecting means for detecting a rotation direction of the swing hydraulic motor, and the direction switching valve. The switching amount detecting means for detecting the switching amount of the above, the mode selecting means for selecting the neutral brake mode and the neutral free mode, and the pressure based on the signals from the rotation direction detecting means, the switching amount detecting means and the mode selecting means. And a controller for controlling the control valve, the controller including detection signals from the rotation direction detecting means and the switching amount detecting means, and the mode selecting means. The operating state of the motor is determined based on these mode selection signals. In (A) Neutral brake mode, I. Directional switching valve is set to high pressure when the directional control valve is in neutral, and II. Swing acceleration Sometimes, the larger the valve switching amount from the neutral position of the direction switching valve to the turning position side, the higher the set pressure of the pressure control valve on the motor inflow side, and III. A control signal for increasing the set pressure of the pressure control valve on the motor discharge side is output. (B) In neutral free mode, i. When the directional control valve is neutral, the set pressure of the pressure control valve is set to low pressure. Ii. During turning acceleration, the larger the switching amount of the directional control valve, the higher the set pressure of the pressure control valve on the motor inflow side, and iii. During turning deceleration, in the direction opposite to the motor rotation direction of the directional control valve. The larger the switching amount of the A turning control device characterized by being configured to output a control signal for increasing the set pressure of the control valve. 2. A swing control device according to claim 1, wherein the pressure control valve is connected to a pipe line connecting both side ports of the swing hydraulic motor and the direction switching valve, and a variable relief valve master valve and a master valve of this master valve. The controller is based on a detection signal from the rotation direction detection means and the switching amount detection means, and a mode selection signal from the mode selection means, and a common slave valve composed of an electromagnetic proportional pressure control valve connected to the pressure control section. (A) In the neutral brake mode, I. When the directional control valve is in neutral, the set pressure of the child valve is set to a high pressure. II. The control valve outputs a control signal that increases the set pressure of the slave valve as the amount of switching to the turning position increases, and III. Increases the set pressure of the slave valve as the amount of switching of the direction switching valve decreases during deceleration of the swing. (B) Neutral pretension In the mode, i. When the directional control valve is neutral, the set pressure of the slave valve is set to a low pressure, and ii. During turning acceleration, the greater the switching amount of the directional control valve, the higher the set pressure of the slave valve, iii. A turning control device configured to output a control signal for lowering the set pressure of the child valve as the switching amount of the directional control valve decreases during turning deceleration.