JPH0276907A - Turn control device - Google Patents

Abstract

PURPOSE:To control an acceleration/deceleration pressure reasonably by raising the set pressure of both electro-magnetic proportional pressure control valve to a high level in the case of a neutral brake mode of a direction control valve and dropping it to a low level in the case of its neutral free mode by respective signals of a detection means and a selection means. CONSTITUTION:A controller 16 judges the running status of a motor based on the detection signals from the rotational direction detection means 14 of a turning hydraulic motor 4 and the switching amount detection means 13 of a direction switching valve 3 and the selection signal from a mode selection means 15 and the set pressure of both electromagnetic proportional pressure control valves 11, 12 is raised to a high level when the direction control valve 3 is neutral in the neutral brake mode. While, the set pressure of both electro- magnetic proportional pressure control valves 11, 12 is dropped to a low level when the direction control valve 3 is neutral in the neutral free mode. Thus, the acceleration pressure and the deceleration pressure of the motor are controlled automatically and reasonably in response to respective modes, both acceleration and deceleration of turn can be performed smoothly and the controllability and workability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a swing control device for construction machines such as hydraulic excavators and hydraulic cranes.

[Conventional technology]

Conventionally, in order to smoothly perform a turning υ111 of a hydraulic crane (for example, Japanese Patent Application Laid-Open No. 53-2137
As shown in Publication No. 9, the setting pressure of a pilot-type variable relief valve provided between circuits on both sides of a swing hydraulic motor is controlled by secondary pressure from a remote control valve (hereinafter referred to as a control valve). It is known what has been done.

(Problems to be Solved by the Invention) The above conventional device switches the directional control valve using the secondary pressure from the remote control valve that is output according to the amount of lever operation, and also switches the variable relief valve on the inflow side of the motor. It controls the acceleration pressure of the motor by controlling the set pressure.
The directional control valve is neutral and all ports open, and when the lever is returned to neutral, the circuits on both sides of the motor are communicated with each other, and the set pressure of both variable relief valves is set to the lower pressure, causing the motor to rotate due to inertia. Since this is a so-called neutral-neutral type, it is not possible to stop the motor with the lever in the neutral position.

When the motor decelerates and stops, the lever is returned to neutral, and then the so-called reverse lever is operated in the opposite direction to the motor rotation direction, and the set pressure of the variable relief valve on the motor discharge side is adjusted according to the amount of the reverse lever operation. The deceleration pressure of the motor is controlled by υIa using the same control pattern.

By the way, in addition to the above-mentioned neutral control system, which rotates the motor by inertia when the lever is returned to neutral, there is also a neutral control system, which stops the rotation of the motor when the lever is returned to neutral. There is a brake system,
Depending on the work content, there are cases where it is better to use the neutral neutral method, and
There are cases where a neutral braking method is better. Therefore, it is desirable to be able to arbitrarily select either method using one machine.

However, the conventional control device described above uses a neutral all-port oven directional switching valve, and in order to control the set pressure of the variable relief valve with the same control pattern both during acceleration and deceleration using the reverse lever, the neutral Applicable only to one-sided brake system, not to neutral brake system.

The present invention has been made to solve these problems, and allows one machine to arbitrarily select between neutral free mode and neutral brake mode depending on the work content, etc. It is an object of the present invention to provide a swing control device that can appropriately control acceleration pressure and deceleration pressure of a motor.

[Means to solve the problem]

4 In order to achieve the above object, the present invention is configured as follows.

(1) In a swing control device that controls the rotation direction of the motor by supplying and discharging oil discharged from a hydraulic pump to and from a swing hydraulic motor via a directional switching valve, the directional switching valve has three positions with a bleed-off passage connected to a neutral PR. It consists of a switching valve, and an electromagnetic proportional pressure control valve is connected to both circuits between both ports of the swing hydraulic motor and the directional switching valve. a detection means, a mode selection means for selecting between a neutral brake mode and a neutral free mode, and a mode selection means for selecting between the two electromagnetic proportional modes when the direction control valve is in neutral and in the neutral brake mode based on signals from each of the detection means and the selection means; A swing control device comprising: a controller that sets the set pressure of the pressure control valve to a high pressure, and sets the set pressure of both the electromagnetic proportional pressure control valves to a low pressure when in a neutral free mode.

(2) In the configuration of (1) above, the controller operates the motor based on the detection signal from the rotation direction detection means of the swing hydraulic motor and the switching amount detection means of the directional switching valve, and the selection signal from the mode selection means. In the neutral brake mode, when the directional control valve is in neutral, the set pressure of both electromagnetic proportional pressure control valves is set to high pressure, and when the directional control valve is in the neutral position, the time between valve switching from neutral to the swiveling position is increased during turning acceleration. As the value increases, the set pressure of the electromagnetic proportional pressure control valve on the motor inflow side is increased, and a control signal is output that increases the set pressure of the electromagnetic proportional pressure control valve on the motor discharge side as the valve switching interval becomes smaller during swing deceleration. In the neutral free mode, when the direction control valve is neutral, the set pressure of both the electromagnetic proportional pressure i, lJ all valves is set to a low pressure, and the electromagnetic proportional pressure control on the motor inflow side increases as the valve switching value increases during turning acceleration. Outputs a control signal that increases the set pressure of the valve and increases the set pressure of the electromagnetic proportional pressure control valve on the motor discharge side as the time between the directional control valve switching in the direction opposite to the motor rotation direction increases during swing deceleration. A swing control device characterized by comprising a control means for controlling.

, (3) In the configuration of (1) above, variable relief valve parent valves are connected to both circuits between both ports of the swing hydraulic motor and the directional control valve, and the pressure of each parent valve is
A common slave valve consisting of an electromagnetic proportional pressure control valve is connected to the section, and the controller operates based on signals from the rotation direction detection means of the swing hydraulic motor, the switching amount detection means of the directional switching valve, and the mode selection means. In the neutral brake mode, when the directional control valve is in neutral, the setting pressure of the slave valve is set to high pressure, and when the directional control valve is in the neutral position, the setting pressure of the slave valve is set to high pressure, and the time between the valve switching from the neutral to the swivel position of the directional control valve is set to high when the directional control valve is in the neutral position. Outputs a control signal that increases the set pressure of the directional control valve that increases, and outputs a control signal that increases the set pressure of the directional control valve that decreases during swing deceleration, and in neutral free mode, when the directional control valve is in neutral. A control signal is output that sets the set pressure of the valve to a low pressure, increases the set pressure of the droplet valve as the valve switching interval increases during swing acceleration, and lowers the set pressure of the droplet valve as the valve switching interval becomes smaller during swing deceleration. A swing control device characterized by comprising υ control means.

[For production]

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

〔Example〕

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the present invention,
In this figure, 1 is a hydraulic pump, 2 is a main relief valve, 3 is a directional control valve, 4 is a swing hydraulic motor, and 5 is an upper rotating body of a construction machine that is rotationally driven by the motor 4. The directional switching valve 3 is a three-position switching valve having a bleed-off passage with a neutral PR connection, and switching of this valve 3 controls the supply and discharge of pressure oil to and from the circuits 6 and 7 on both sides of the motor 4.
The rotation of the motor 4 is controlled. 8.9 is a check valve for preventing cavitation, and 10 is a tank.

In this hydraulic circuit, electromagnetic proportional relief valves (or electromagnetic proportional pressure reducing valves) 11 and 12 are connected to the circuits 6 and 7 between the ports on both sides of the motor 4 and the directional control valve 3, respectively, at the closing circles of the electromagnetic proportional pressure control valves. has been done. The directional switching valve 3 is provided with a sensor 13 for detecting a spool stroke (or a lever operation angle) as switching amount detection means, and the motor 4 is provided with a rotation direction sensor 14. 15
is a mode selection means for selecting either neutral brake mode or neutral free mode. The controller 16 selects the electromagnetic proportional relief valves 11.12 based on the selection signal from the mode selection means 15 and the detection signals from the respective sensors 13.14.
Outputs the set pressure control signal to.

Next, turning control will be explained.

■-■ Neutral brake mode First, select the neutral brake mode using the mode selection means 15, and operate the operation lever to the push side to switch the directional control valve 3 to the push side (right position side in the figure). The discharged oil is supplied to the motor 4 via the circuit 6, the pressure in the circuit 6 increases, the motor 4 is accelerated in forward rotation, the revolving body 5 is accelerated in the right direction, and the discharged oil from the motor 4 is supplied to the circuit 7 and It is returned to the tank 10 via the directional control valve 3.

During this turning acceleration, the spool stroke of the directional control 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 by the sensor 14. is input to the controller 16, and the control shown in the flowchart of FIG. 2 is performed.

1, that is, in FIG. 2, when the program starts, the detected value by the stroke sensor 13 is read in step S1, the rotation direction (normal rotation) of the motor 4 detected by the rotation direction sensor +j14 is read in step S2, In step S3, 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 in step S3 it becomes "l N OL", in step $4 it becomes "Y E S", and in step S5 it becomes "Y E S" depending on whether the motor 5 rotates in the forward direction.
Then, in the neutral brake mode at step Sθ, the state becomes "'Y E S", and the process proceeds to step S7.

Then, a control signal with an acceleration pattern shown in solid line A in FIG. 3 is output to the relief valve 11 on the inflow side of the motor 4, and a control signal with a deceleration pattern shown in the solid line in the figure is output to the relief valve 12 on the motor discharge side. is output, and depending on the spool stroke of the directional control valve 3, the set pressure of the relief valve 11 changes from low pressure to high pressure (for example, 3
0 to 190 kg/cd), and the set pressure of the relief valve 12 is controlled in a range from high pressure to low pressure (for example, 190 to 3 (1/cat)) along the deceleration pattern.

In this case, the directional valve 3 has a bleed-off passage, which in neutral bleeds off the entire set of the discharge flow rate of the pump 1 to the tank 10, and as the spool stroke increases, the bleed-off flow rate from the pump 1 to the tank 1o is reduced. The flow rate flowing into the circuit 6 is gradually increased while throttling.The pressure uniquely determined by the flow rate control of the directional control valve 3 is O at neutral, and although it varies somewhat depending on the pump discharge flow rate, it is generally within the range where the spool stroke is small. In the low pressure range, the curve is gentle and υJIII, and in the large spool stroke range, the pressure is high with a sharp curve. For this reason, if the pressure (acceleration pressure) on the inflow side of the motor 4 is controlled only by controlling the flow rate using the directional switching valve 3, controllability in the low pressure region is good, but controllability in the high pressure region becomes poor.

However, by controlling i as described above, the acceleration pressure of the motor 4 is reduced by Rffi & lI t of the directional control valve 3.
Of the pressure determined by ll and the pressure on the low pressure side of the set pressure of the relief valve 11, it is υ1@, and in a range where the spool stroke is small (low pressure region), the flow control tll (pressure In the range where the spool stroke is large (high pressure range), priority is given to control by the set pressure of the relief valve 11, and control is performed smoothly over the entire spool stroke, greatly improving controllability, and the motor 4 is Accelerates smoothly.

However, when the directional control valve 3 is returned to the neutral direction, the opening area of the passage from the motor 4 of the directional control valve 3 to the tank 10 is narrowed, but since the motor 4 rotates forward due to inertia, the motor discharge side The pressure in circuit 7 gradually increases, and the pressure (
The motor 4 is decelerated by the deceleration pressure). At this time, during the return operation of the directional control valve 3, the spool stroke is still on the push side ('YES' in step S4), and the motor 4 is rotating forward due to inertia ('Y' in step S5).
ES"), the set pressure of the relief valve 12 on the discharge side of the motor 4 is controlled according to the deceleration pattern (solid line in Figure 3) through steps S1 to S7, and the directional control valve 3 is set to neutral by this ti control. As it is returned, the deceleration pressure of the motor 4 gradually increases, and the motor 4 is decelerated more efficiently.

In addition, during acceleration and deceleration of the above-mentioned turning, even if the lever is pushed or pulled to the push side rather than neutral, as long as the lever is on the push side and as long as the motor 4 is rotating forward, the motor inflow side will The relief valve 11 is controlled according to the acceleration pattern (solid line A), and the relief valve 12 on the motor discharge side
is controlled according to a deceleration pattern (shown by the solid line above), and the acceleration pressure and deceleration pressure of the motor 4 are appropriately controlled according to the spool stroke, so that acceleration and deceleration are performed smoothly.

When the directional control valve 3 is stopped at the neutral position after the swing deceleration, the supply of pressure oil from the pump 1 to the motor 4 is stopped.
The oil discharged from the motor 4 to the tank 10 is also blocked, and the pressure in the circuit 7 on the motor discharge side increases rapidly. At this time, the answer is "YES" in step S3, and since the mode is the neutral brake mode, the answer is "YES" in step S8, and the process proceeds to step S9.Then, the set pressure of the relief valve 12, which was on the motor discharge side, is set to high pressure (for example, At the same time, the set pressure of the relief valve 11 on the motor inflow side is also controlled to a high pressure (for example, 190 Kg/d), and the motor 4 is braked at high pressure.

Furthermore, when decelerating or stopping the above-mentioned turning, if the reverse lever is operated on the direction switching valve 3 from the push side to the pull side beyond the neutral position,
Discharge oil from the pump 1 flows into a circuit 7 on the discharge side of the motor 4, and a circuit 6 on the inflow side is communicated with the tank 10. At this time, in step S4, the state becomes "I N Ole", and while the directional control valve 3 was operated to the pull side, the motor 4 is rotating forward due to inertia, so it becomes "N O" in step Sw+, and furthermore, the neutral brake is activated. mode, the result is "YES" at step $11, and the process advances to step S12. Then, while the set pressure of the relief valve 12 on the motor discharge side is maintained at a high pressure (dotted line c in the above), the set pressure of the relief valve 11 on the motor inflow side decelerates in a deceleration pattern (solid line in the above).
The pressure is controlled so that the pressure gradually decreases along the line. This prevents the deceleration pressure from decreasing even if the reverse lever is operated.
The pressure remains high, and the discharged oil from the motor 4 and the pressure oil from the pump 1 flow into the circuit 7, and the motor 4 is quickly braked.

In addition, in this neutral brake mode, the directional control valve 3
When is neutral, the set pressures of both relief valves 11 and 12 are controlled to a high pressure, whereas during turning acceleration, control of the set pressure of the relief valve 11 on the motor inflow side starts from a low pressure. As mentioned above, in the small range of the spool stroke at the initial stage of the control, the control by the directional control valve 3 is given priority, and in the large range of the spool stroke, the control by the relief valve 11 is given priority, so there is no risk of hunting etc. There is no risk of hindrance to turning control.

Furthermore, if the directional control valve 3 is held in the neutral position after braking the motor 4, both circuits 6.7 are blocked and the steps S1→S2→S3→S4→S8→S
Since the set pressures of both the relief valves 11 and 12 are maintained at a high pressure by the valves 9, the stopped state of the motor 4 is reliably maintained, and there is no fear that the upper rotating body 5 will rotate freely due to wind pressure or the like. Moreover, even on a slope, there is no fear that the upper rotating body 5 will rotate freely in the direction of the descending board, and safety is improved.

When the directional control valve 3 is switched to the pull side in the neutral brake mode, the oil discharged from the pump flows into the motor 4 through the circuit 7, the motor 4 is reversed, and the rotating body 5 is rotated to the left. Oil discharged from the motor 4 is returned to the tank 10 via the circuit 6 and the directional control valve 3. During this turning acceleration and deceleration, the relief valve 12 becomes the motor inflow side and the relief valve 11 becomes the motor discharge side, and in the flowchart of Fig. 2, steps S1→S2→S3→S4→S1°→S
tI→S%, the set pressure of the relief valve 12 on the motor inflow side is controlled according to the acceleration pattern (solid line H), and the set pressure of the relief valve 11 on the motor discharge side is controlled according to the deceleration pattern (solid line H). ), and thereafter the motor 4 is smoothly accelerated and decelerated by the same action as above.

After that, if the directional control valve 3 is returned to neutral, step S3→
The process progresses from S8 to S9, and the set pressures of both relief valves 11 and 12 become high pressures, and the rotating body 5 is reliably held in neutral. Furthermore, if the reverse lever is operated, step S4→
Proceeding from S5 → S15 → 5111, the set pressure of the relief valve 11 on the motor discharge side remains at a high pressure (toward the broken line as above), and the set pressure of the relief valve 12 on the motor inflow side changes to the deceleration pattern (as indicated by the solid line as above). The rotation is controlled to decelerate and stop quickly.

■−■ Neutral free mode is selected by the neutral free mode mode selection means 15,
Operate the operating lever of the directional control valve 3 to the push side to turn the motor 4
When rotating the rotating body 5 in the right direction, steps 81 to S6 are processed in the same way as when accelerating the turning in the neutral brake mode of the knee ■ above, but in step S6, the result is 'NO'. , the process advances to step Sν.Then, the set pressure of the relief valve 11 on the motor inflow side changes to the acceleration pattern (
While the pressure is controlled along the solid line A), the set pressure of the relief valve 12 on the motor discharge side is maintained at a low pressure (broken line G). Therefore, the acceleration pressure of the motor 4 is
As in case ①, the pressure i, II 111 caused by the flow rate control of the directional control valve 3,
It is determined by the pressure on the low pressure side of the set pressure of 1, and in the range where the spool stroke is small (low pressure range), flow control @ (pressure control) by the directional control valve 3 is given priority, and in the range where the spool stroke is large (high pressure range) ), relief valve 11
Control is prioritized based on the set pressure, and the motor 4 is smoothly accelerated.

However, in this neutral free mode, as long as the direction switching piece 3 is on the push side, the set pressure of the relief valve 12 on the deceleration side remains low (as shown by the broken line in the above), so the direction switching valve 3 is returned to the neutral direction. Even if the brake is operated, the deceleration pressure remains low, and a large braking force is not applied as in the case of the neutral brake mode.

When the directional control valve 3 is returned to neutral, the circuits 6 and 7 on both sides of the motor 6 are blocked by the directional control valve 3, but at this time, ``Y E S'' is selected in step S3, and step S is
8, the process proceeds to step S+a, where the set pressures of the relief valves 11 and 12 on both sides are both controlled to a low pressure (for example, 30 kg/7).

Therefore, the oil discharged from the motor 4 passes through the relief valve 12 and is relieved into the tank 10 at low pressure, and the oil flows into the inlet side of the motor 4 from the tank 10 via the check valve 8. It will continue to rotate. Therefore, so-called swirling operation is possible with the lever in the neutral position.

When the directional control valve 3 is reverse lever operated from the push side to the pull side beyond neutral after acceleration of the above-mentioned turning, the oil discharged from the pump 1 flows into the circuit 7 on the discharge side of the motor 4, and the circuit 6 on the inflow side It is communicated with the tank 10. At this time, the result in step S4 is "No", and while the directional control valve 3 has been operated to the pull side, the motor 4 is rotating forward due to inertia, so the result in step S10 is 'NO', and furthermore, the neutral free mode, the determination in step S11 is NO'' and the process advances to step S19. Then, while the set pressure of the relief valve 11 on the motor inflow side remains at a low pressure (dotted line H), the set pressure of the relief valve 12 on the motor discharge side gradually increases along the acceleration pattern (solid line H). controlled as follows. As a result, the deceleration pressure is controlled according to the operation amount of the reverse lever operation, and the motor 4 is smoothly decelerated.

In addition, when switching the directional control valve 3 to the pull side in the neutral free mode and rotating the rotating body 5 to the left by rotating the motor 4 in reverse, and after the acceleration, the directional control valve 3 is switched from the neutral to the push side using the reverse lever. When operating to decelerate and stop, the same control as above is performed.

FIG. 4 is a hydraulic circuit diagram showing a second embodiment of the present invention,
In this embodiment, variable relief valve master valves 17.
18 is connected, and a check valve 19.2 is connected to the control section of each master valve.
Common child valve 21 consisting of an electromagnetic proportional relief valve through 0
is connected, and the child valve 21 is controlled by a controller 22. Note that the other configurations are substantially the same as the embodiment shown in FIG. 1, and therefore, the same parts are given the same reference numerals.

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

■-■ Neutral Brake Mode First, when the neutral brake mode is selected by the mode selection means 15, the directional control valve 3 is switched to the push side, the motor 4 is rotated in the normal direction, and the rotating body 5 is to be rotated to the right, the first As in the embodiment shown, the signals from each sensor 13, 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 detected value by the stroke sensor 13 is stored in step S20, the difference between the detected value of the stroke sensor 13 and the above-mentioned stored value is calculated in step S22, and the detected value by the rotation direction sensor 14 is calculated in step S22. The detected rotation direction (forward rotation) of the motor 4 is read,
Step S23: Neutral brake mode
In step S24, it is determined whether or not the spool of the directional control valve 3 is in an accelerated state based on the calculated value in step S21.Here, the accelerated state refers to the state in which the directional control valve Whether the spool of the directional control valve 3 is on the push side or the pull side, the spool moves away from the neutral position.On the contrary, the deceleration state (step 527) means that the spool of the directional control valve 3 is on the push side or the pull side. Refers to the operating state in which the spool returns to the neutral position regardless of whether it is on the pull side.

Therefore, during this turning acceleration, in step S24, '
YES'', and NO'' by pressing the reverse lever in step S25, and the process proceeds to step S26. Then, the third valve is placed in the child valve 21.
The control signal of the acceleration pattern shown in the solid line A in the figure (however, when accelerating by switching the directional control valve 3 to the pull side, the solid line E) is output, and the set pressure of the child valve 21 changes to the spool stroke of the directional control valve 3. Depending on the pressure, from low pressure to high pressure (e.g. 30~1
IIIJWJ in the range of 9 (1 g/cal). In this case, since the slave valve 21 is common to the parent valves 17 and 18, the set pressure of the variable relief valve master valve 17 on the inflow side of the motor 4 and the set pressure of the relief valve master valve 18 on the discharge side are different. Always equally controlled.

In this way, during turning acceleration, the acceleration pressure of the motor 4 is determined by the pressure on the lower pressure side of the pressure determined by the flow rate control of the directional control valve 3 and the set pressure of the variable relief valve master valve 17 controlled by the slave valve 21. The motor 4 is smoothly accelerated in the same way as in the cases ①-② in the first embodiment.

However, in this second embodiment, when the directional control valve 3 is returned to the neutral direction, "No" is returned in step 824, "YES" is obtained in step 827 because the spool is in a deceleration state, and the reverse lever in step S2δ is The answer is "No" and the process advances to step S29. Then, the control signal of the deceleration pattern shown in the solid line port in FIG. Parents dialect 17.18
The set pressure is controlled to be high enough to return the directional control valve 3 to the neutral position, and the deceleration pressure of the motor 4 is controlled by the relief valve parent valve 18 on the motor discharge side, so that the motor 4 is efficiently decelerated.

In this way, in the second embodiment, when accelerating the motor 4 in the neutral brake mode, the set pressure of the child valve 21 is controlled according to the acceleration pattern (solid line A or E as above), and when decelerating the motor 4, The set pressure of the child valve 21 is reduced to a deceleration pattern (
By controlling along the solid line 2) above, acceleration and deceleration of the motor 4 can be performed smoothly. In this case, the motor inlet side and the motor outlet side are equally controlled, but only one pressure is required to control acceleration and deceleration, so there is no risk of interfering with turning control.

Furthermore, when the directional control valve 3 is stopped at the neutral position after the swing deceleration, the circuits 6 and 7 on both sides of the motor 4 are blocked, and the result in step S24 is "No" and the result in step 52yT is "No". In Q, Sarah □', the spool in step 830 is neutral, ``YES'', and the process proceeds to step S31.Then, a high pressure control signal is output to the child valve 21, and the set pressure of the child valve 21, that is, both leaf valves, is output. The set pressure of the master valve 17.18 is high (for example, 19ON9/
cj), the motor 4 is braked at high pressure, and the stopped state of the motor 4 is reliably maintained.

Note that when the directional control valve 3 is operated from the push side to the pull side beyond neutral when decelerating or stopping the above-mentioned turning, the operation will result in an acceleration state to the pull side, so step S
24 becomes "'YES". However, since this is a reverse lever operation, the result in step S25 is YES, and the process proceeds to step S31, in which a high-pressure control signal (dotted line C or B) is output to the child valve 21, and both leaf valves are activated. The set pressure of the master valves 17 and 18 will be maintained at a high pressure.

Therefore, even if the reverse lever is operated, the deceleration pressure does not decrease, and the motor 4 is quickly braked.

■−■ Neutral free mode is selected by the neutral free mode mode selection means 15,
Switch the directional control valve 3 to the push side to rotate the motor 4 in the normal direction,
When rotating the rotating body 5 to the right, the above step S
23 is in the neutral brake mode, the process goes to step S26, where the set pressures of both leaf valve master valves 17 and 18 are controlled via the child valve 21 according to the acceleration pattern (solid line A or E in the same figure). In this case, the set pressure is always controlled according to the acceleration pattern (solid line A or E above), so when accelerating, the turning is smoothly accelerated by the same effect as in the neutral brake mode of ■-■ above. However, when the directional control valve 3 is returned to the neutral position after the turning acceleration, the above-mentioned set pressure becomes lower as it approaches the neutral position, and becomes the lowest (for example, 3ONy/cal) at the neutral position, so that the lever It is possible to perform swirling operation using inertia in the neutral position.

After that, when the directional control valve 3 is reverse lever operated, for example, from the push side to the pull side beyond neutral, the set pressure is controlled according to the acceleration pattern, and the operation amount of the reverse lever (suburse i loaf) increases. As the pressure increases, the set pressure of the relief valve becomes higher, and the motor 4 is decelerated and stopped by this pressure.

Note that when the directional switching valve 3 is switched to the pull side to accelerate the turn, the same control as described above is performed when the directional switching valve 3 is then returned to the neutral position and the reverse lever is operated to the push side.

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

〔Effect of the invention〕

As described in 1 above, according to the present invention, by selecting a work mode with the mode selection means depending on the work content etc., a neutral brake that automatically stops the motor when the lever is returned to neutral is provided in one machine. mode and a neutral free mode in which the motor is rotated by inertia when the lever is returned to neutral, which can be used as desired, improving the versatility of the machine.

Further, the acceleration pressure and deceleration pressure of the motor can be automatically and appropriately controlled according to each mode, and both the acceleration and deceleration of turning can be performed smoothly, and controllability and workability can be improved.

Furthermore, by controlling the relief valve set pressure using a common slave valve, a small-sized electromagnetic proportional relief valve can be used, and the structure can be simplified and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing a 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 setting pressure. FIG. 4 is a hydraulic circuit diagram showing the second embodiment, and FIG. 5 is a control flowchart of the second embodiment. DESCRIPTION OF SYMBOLS 1...Hydraulic pump, 3...Directional switching valve, 4...Swivel hydraulic motor, 5...Upper rotating 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 parent valve, 21... Child valve (electromagnetic proportional relief valve), 22... Controller. Patent applicant: Kobe Steel, Ltd. Agent
Patent Attorney Etsushi Kotani Patent Attorney Chief 1
) 1 Patent Attorney Takao Ito No. 1 Figure 3 Figure ↑ Previous ← Medium → Pull 5 Standing stool stroke (mm) Figure 4

Claims (3)

[Claims] 1. In a swing control device that controls the rotation direction of the motor by supplying and discharging oil discharged from a hydraulic pump to and from a swing hydraulic motor via a directional switching valve, the directional switching valve is a 3-position switching valve having a bleed-off passage connected to a neutral PR. The electromagnetic proportional pressure control valve is connected to both circuits between the both side ports of the swing hydraulic motor and the directional switching valve, and includes a rotating direction detection means of the swing hydraulic motor, a switching amount detection means of the directional switching valve, mode selection means for selecting between neutral brake mode and neutral free mode; and mode selection means for selecting both of the electromagnetic proportional pressure control valves when the directional control valve is in neutral and in neutral brake mode based on signals from each of the above-mentioned detection means and selection means. Set pressure to high pressure,
A swing control device comprising: a controller that sets the set pressures of both of the electromagnetic proportional pressure control valves to a low pressure when in a neutral free mode. 2. The controller determines the operating state of the motor based on the detection signal from the rotation direction detection means of the swing hydraulic motor and the switching amount detection means of the directional switching valve, and the selection signal from the mode selection means, and selects the direction in neutral brake mode. When the control valve is in neutral, the set pressure of both electromagnetic proportional pressure control valves is set to a high pressure, and the larger the valve switching amount from the neutral to the swing position of the directional control valve during swing acceleration, the higher the electromagnetic proportional pressure control on the motor inflow side. A control signal is output that increases the set pressure of the valve, and the smaller the valve switching amount becomes during swing deceleration, the higher the set pressure of the electromagnetic proportional pressure control valve on the motor discharge side.In neutral free mode, the directional control valve is in neutral. At this time, the set pressure of both electromagnetic proportional pressure control valves is set to a low pressure, and the larger the switching amount of the valve is during swing acceleration, the higher the set pressure of the electromagnetic proportional pressure control valve on the motor inflow side is. A claim characterized in that the control means is provided for outputting a control signal that increases the set pressure of the electromagnetic proportional pressure control valve on the motor discharge side as the amount of valve switching in the direction opposite to the motor rotation direction increases. 1
The swing control device described. 3. Variable relief valve master valves are connected to both circuits between both ports of the swing hydraulic motor and the directional control valve, respectively, and a common slave valve consisting of an electromagnetic proportional pressure control valve is connected to the pressure control section of each master valve, The controller determines the operating state of the motor based on each signal from the rotation direction detection means of the swing hydraulic motor, the switching amount detection means of the directional control valve, and the mode selection means, and selects the directional control valve in the neutral brake mode. The set pressure of the child valve is set to a high pressure when the is in neutral, and the set pressure of the child valve is set high as the amount of valve switching from the neutral to the swing position of the directional control valve increases during swing acceleration, and the above valve switch is set when the swing is decelerated. Outputs a control signal that increases the set pressure of the child valve as the amount decreases, and in neutral free mode, sets the set pressure of the child valve to a low pressure when the directional control valve is in neutral, and increases the valve switching amount during turning acceleration. The swing according to claim 1, further comprising a control means for outputting a control signal for increasing the set pressure of the switch valve and lowering the set pressure of the switch valve such that the valve switching amount becomes smaller during swing deceleration. Control device.