JPH0776858A - Hydraulic pressure control device for working machinery - Google Patents

Abstract

PURPOSE:To speed up the operating rate of an actuator in conformity with a manipulated variable of an operation lever and control an adjustable speed which is required to change the operating rate of the actuator by way of the operation of the operation lever, and further control the drive force of the actuator by way of the operation lever. CONSTITUTION:A target turning speed Nr of an upper part turning body 2 is set in conformity with a manipulated variable R of an operation lever 12 while differential pressures prevailing between input and output ports 1a and 1b of pressure oil of a hydraulic pump, which is a drive force of the upper part turning body 2, are predetermined in order to eliminate differential pressures by means of proportional integral control based on deviations (Nr-N) between the target operation speed Nr and a actual operation speed N of the upper part turning body 2. A pressure control device 15 is designed to control the differential pressure (Pa-Pb) of the hydraulic pump 1 so as to attain the predetermined differential pressure. The setting value of the differential pressure is set so that it may be increased as an arithmetic operation value of the proportional integral becomes larger. In the case of N 0 an integral term of the proportional arithmetic operation must be a fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device for a construction machine such as a hydraulic excavator and a working machine for civil engineering work.

[0002]

2. Description of the Related Art For example, in a hydraulic excavator, a hydraulic cylinder for driving an arm, a boom and a bucket,
An actuator such as a turning hydraulic motor and an operating lever for driving and operating these actuators are provided.
Pressure oil is supplied to the actuator from a hydraulic pump in accordance with the operation of the operation lever to drive the actuator.

In a work machine of this type, a so-called, in order to supply an actuator with a flow rate according to the operation amount of the operation lever and obtain an operating speed of the actuator according to the operation amount of the operation lever, It is known that a load sensing system is adopted.

In this load sensing system, basically, a spool of a direction switching valve provided between the hydraulic pump and the actuator for switching the operating direction of the actuator is provided with an opening area proportional to the operation amount of the operating lever. With a pressure compensation for maintaining the differential pressure between the inflow side (hydraulic pump side) and the outflow side (actuator side) of the pressure oil of the directional control valve at a predetermined set value. By providing a flow control valve and maintaining a constant differential pressure between the inflow side and the outflow side of the directional control valve,
The flow rate of the pressure oil flowing into the actuator is proportional to the opening area of the directional control valve, in other words, the operation amount of the operating lever. The flow rate is ensured according to the manipulated variable.

By the way, for the operator of this type of work machine, in performing an appropriate work, the operation speed of the actuator corresponding to the operation amount (operation position) from the neutral position of the operation lever can be obtained as a matter of course. It is preferable that the operating speed of the actuator changes in response to the operation speed when the operation lever is operated from one operation position to another operation position, and the acceleration / deceleration of the actuator corresponding to the operation speed of the operation lever is obtained. Further, for example, in a hydraulic excavator, when the work is performed while pressing the bucket against the work, it is preferable that a pressing force corresponding to the operation amount of the operation lever can be obtained.

However, in the conventional load sensing system, when the operation amount of the operation lever is increased to increase the operating speed of the actuator, for example, the operation amount after the increase is finally dealt with. Although the operating speed of the actuator can be obtained, the acceleration of the actuator at this time often does not correspond to the operating speed of the operating lever. That is, a working machine such as a hydraulic excavator generally has a large inertial force due to a large load on the actuator, so that the operation amount of the operation lever is increased to increase the operating speed of the actuator, thereby increasing the flow rate to the actuator. Even if it is increased, the operating speed of the actuator does not immediately increase. Therefore, the pressure of the pressure oil flowing into the actuator rapidly increases to the maximum pressure set by the overload relief valve or the like, and the maximum pressure causes the actuator to accelerate. Then, such an inconvenience similarly occurs when the work is performed while the operation amount of the operation lever is constant and when the load pressure of the actuator changes.

Further, in the conventional load sensing system, when the pressing work is performed, the pressure of the pressure oil flowing into the actuator rises to the maximum pressure because the actuator cannot move regardless of the operation amount of the operation lever, Therefore, the actuator is driven by the pressing force corresponding to the maximum pressure, and the pressing force cannot be controlled by the operating lever.

As disclosed in, for example, Japanese Patent Laid-Open No. 3-157501, a relief valve for controlling the inflow pressure of pressure oil to the actuator is provided on the basis of the load sensing system. There is also known one in which the set pressure is set according to the operation amount (operation position) of the operation lever, but in this one, the pressure of the pressure oil flowing into the actuator is determined according to the operation position of the operation lever. In other words, since the acceleration / deceleration of the actuator is determined according to the operating position of the operating lever, the acceleration / deceleration of the actuator when the operating lever is operated from one position to another is It is decided by the final operating position of the lever. Therefore, the operator cannot control the acceleration / deceleration when the operator operates the operation lever to change the operating speed of the actuator.

[0009]

In view of the background described above, the present invention can quickly obtain the operating speed of the actuator in response to the operation amount of the operating lever, and the acceleration / deceleration when changing the operating speed of the actuator. An object of the present invention is to provide a hydraulic control device for a working machine, which can be controlled by operating an operation lever, and can further control the driving force of an actuator by operating the operation lever when performing a pressing operation or the like.

[0010]

In order to achieve such an object, the present invention provides a hydraulic control apparatus for a working machine, which supplies pressure oil from a hydraulic pump to an actuator in response to an operation of an operating lever to drive the actuator. A speed detecting means for detecting an operating speed of the actuator, an operation amount detecting means for detecting an operation amount of the operation lever, and an actuator amount of the actuator according to an operation amount of the operation lever detected by the operation amount detecting means. Target speed setting means for setting a target operating speed, and pressure oil of the actuator according to a deviation between the target operating speed set by the target speed setting means and the operating speed of the actuator detected by the speed detecting means. The differential pressure setting means for setting the differential pressure between the inlet and the outlet in the direction to eliminate the deviation, and the differential pressure setting means. Pressure control means for controlling the pressure of the inlet and outlet of the pressure oil of the actuator to obtain a fixed differential pressure, the differential pressure setting means, between the target operating speed and the operating speed of the actuator. It has a proportional-plus-integral calculation means for calculating a sum of a proportional term obtained by multiplying the deviation by a predetermined proportional gain and an integral term formed by integrating the deviation within a predetermined integration time. The differential pressure is set to a larger value as the calculated value is larger.

Further, when the operating speed of the actuator detected by the speed detecting means is a low speed which is substantially zero, the proportional-plus-plus-integral calculating means sets the proportional term as a predetermined fixed value for the integral term. It is characterized by finding the sum of and.

Further, the target speed setting means sets the target operating speed such that the increase rate of the target operating speed with respect to the operating amount of the operating lever increases as the operating amount of the operating lever increases. Characterize.

Further, when the operating speed of the actuator detected by the speed detecting means is substantially zero and the operation amount of the operation lever detected by the operation amount detecting means is substantially zero, the actuator is operated. It is characterized in that a closing means for closing the inflow path and the outflow path of the pressure oil is provided.

[0014]

According to the present invention, the differential pressure setting means detects the target operating speed of the actuator set by the target speed setting means according to the operation amount of the operating lever and the speed detecting means detected by the speed detecting means. In order to eliminate the deviation from the actual operating speed of the actuator, in other words, so that the actual operating speed of the actuator matches the target operating speed corresponding to the operation amount of the operating lever, the flow of pressure oil of the actuator is A pressure difference between the inlet and the outlet is set, and at this time, the pressure control means controls the actual pressure difference between the inlet and the outlet of the pressure oil of the actuator to obtain the set pressure difference, that is, The acceleration / deceleration of the actuator determined by the differential pressure is controlled. Specifically, for example, when the actual operating speed of the actuator is lower than the target operating speed, the pressure at the inlet of the pressure oil of the actuator is made higher than the pressure at the outlet to increase the operating speed of the actuator. When the actual operating speed of the actuator is higher than the target operating speed, the pressure at the inlet of the pressure oil of the actuator is made lower than the pressure at the outlet of the actuator to reduce the operating speed of the actuator. Then, at this time, the differential pressure setting means sets the differential pressure in correspondence with the magnitude of the sum of the proportional term and the integral term obtained by the proportional-plus-integral calculation means. The actual operating speed of the actuator quickly converges to the target operating speed according to the operation amount of the operation lever.
Therefore, the operating speed corresponding to the operation amount of the operating lever can be quickly obtained. Further, when the operation amount is changed from an arbitrary operation amount of the operation lever, the larger the change amount is,
Since the target operating speed also largely changes, the deviation becomes large, and thus the set value of the differential pressure also becomes large, and the acceleration / deceleration of the actuator corresponding to the operation speed of the operation lever is obtained.

In such control, when the pressing operation is performed by the actuator, the operating speed of the actuator is forcibly maintained at substantially zero, so that the operating speed of the actuator depends on the operation amount of the operating lever. It is not possible to match the target operating speed, so
The integral term continuously increases, so the sum of the integral term and the proportional term also increases, and the differential pressure of the actuator also increases. Therefore, the pressing force of the actuator increases regardless of the operation amount of the operation lever. Therefore, when the operating speed of the actuator detected by the speed detecting means is a low speed that is substantially zero, the sum of the integral term and the proportional term is obtained by using the integral term as a predetermined fixed value. By doing so, the set value of the differential pressure, that is, the pressing force of the actuator is the deviation (in the case of pressing work, the operating speed of the actuator is substantially zero, so the deviation substantially matches the target operating speed. ), The pressing force of the actuator corresponding to the operation amount of the operation lever can be obtained.

In the case where the target speed setting means sets the target operating speed such that the increase rate of the target operating speed with respect to the operating amount of the operating lever increases as the operating amount of the operating lever increases. The smaller the operation amount of the operation lever, the smaller the change in the target operating speed with respect to the change in the operation amount, and the fine speed operation of the actuator can be performed.

In the proportional-plus-integral control, when the operation amount of the operating lever is substantially zero, the target operating speed is also set to substantially zero, so that the actuator is basically kept in a stopped state. However, minute movements of the actuator may occur due to load fluctuations of the actuator. Therefore, when the operating speed of the actuator detected by the speed detecting means is substantially zero and the operation amount of the operation lever detected by the operation amount detecting means is substantially zero, the closing means causes the actuator to operate. The inflow and outflow paths of the pressure oil are blocked. By doing so, the flow of pressure oil in the actuator is completely stopped, so that the actuator is reliably maintained in the stopped state.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described with reference to FIGS. FIG. 1 is a system configuration diagram of a hydraulic control device of the present embodiment, FIG. 2 is a block configuration diagram of a main part of the hydraulic control device, and FIGS. 3 to 7 are diagrams for explaining the operation of the hydraulic control device. is there.

Referring to FIG. 1, the hydraulic control system of the present embodiment is a system for controlling a turning hydraulic motor (actuator), which is one of the actuators provided in a hydraulic excavator, for example. A swing hydraulic motor for swing-driving the upper swing body 2 of the hydraulic excavator via a speed reducer 3.
Reference numeral 4 is a variable displacement hydraulic pump that supplies pressure oil to the hydraulic motor 1, and 5 is an electromagnetic operation direction for switching the direction of supply of pressure oil from the hydraulic motor 1 to the hydraulic motor 1 to switch the rotation direction of the hydraulic motor 1. The switching valves 6a and 6b are electromagnetic proportional flow rate control valves connected to the pair of inflow / outflow ports 1a and 1b of the hydraulic motor 1 via pipes 7a and 7b, respectively.
Is an oil tank that stores the oil sucked and discharged by the hydraulic pump 4.

At the neutral position A, the directional control valve 5 closes the pipe line 9 led out from the discharge port of the hydraulic pump 4, and at the same time, the directional control valve 5 is controlled by the electromagnetic proportional flow control valves 6a and 6b. Side 10a, 10 led to the side
b is communicated with the oil tank 8. In addition, the direction switching valve 5
At the position B, the hydraulic pump 4 side conduit 9 is connected to the electromagnetic proportional flow control valve 6a side conduit 10a, and the electromagnetic proportional flow control valve 6b side conduit 10b is throttled to the oil tank 8a. Can be connected via. Further, the directional control valve 5 connects the hydraulic pump 4 side conduit 9 to the electromagnetic proportional flow rate control valve 6b side conduit 10b at the C position, and the electromagnetic proportional flow rate control valve 6b side conduit 10b. It communicates with the oil tank 8 through the throttle 5b.

In such a hydraulic circuit, the pressure oil sucked and discharged from the oil tank 8 by the hydraulic pump 4 is connected to the pipe 9, the direction switching valve 5, and the pipe when the direction switching valve 5 is switched to the B position. 10a, electromagnetic proportional flow control valve 6a and pipe 7
The pressure oil that is supplied to the hydraulic motor 1 via a in sequence and flows out from the hydraulic motor 1 at this time is transferred to the oil tank via the conduit 7b, the electromagnetic proportional flow control valve 6b, the conduit 10b and the direction switching valve 5. Recovered in 8. At this time, the hydraulic motor 1
Rotates in a direction corresponding to the flow direction of the pressure oil, whereby the upper swing body 2 of the hydraulic excavator is driven to swing rightward, for example. Further, when the direction switching valve 5 is switched to the C position, the pressure oil discharged from the hydraulic pump 4 flows in the hydraulic motor 1 in the opposite direction to the case of the B position, whereby the rotation of the hydraulic motor 1 is reversed. Then, the upper swing body 2 of the hydraulic excavator is driven to swing leftward, for example.

In FIG. 1, 11 and 11 are overload relief valves for setting the maximum pressure of the circuit.

Further, referring to FIGS. 1 and 2, reference numeral 12 is an operating lever for an operator to drive / operate the hydraulic motor 1, and 13 is an operation amount R from the neutral position of the operating lever 12.
An operation amount detector (operation amount detecting means) for detecting (including an operation direction), 14 is a speed sensor (speed detecting means) for detecting a turning speed N of the upper swing body 2 of the hydraulic excavator, and 15 is the electromagnetic proportional flow rate. A pressure control device (pressure control means) for controlling the differential pressure between the inflow / outflow ports 1a, 1b of the hydraulic motor 1 by the control valves 6a, 6b, 16 is a pump control device for controlling the discharge pressure of the hydraulic pump 4, and 17 is The direction switching valve 5 is switched and driven according to the operation direction of the operation lever 12, and a command signal is sent to the pressure control device 15 and the pump control device 16 according to the operation amount of the operation lever and the swing speed of the upper swing body 2. It is the main controller that outputs.

The operating lever 12 is swingable to the left and right as shown by an arrow X in FIG. 1, and when the operator wants to turn the upper swing body 2 to the right, the operating lever 1 is rotated.
When the user wants to swing 2 to the right and swing the upper swing body 2 to the left, the operation lever 12 is swung to the left. The operation amount detector 13 is composed of, for example, a potentiometer, and outputs a signal corresponding to the operation amount R of the operation lever 12 to the main controller 17.

The pressure control device 15 includes the electromagnetic proportional flow control valves 6a and 6b and the inflow / outflow port 1 of the hydraulic motor 1.
The electromagnetic proportional flow rate control valve 6a is driven by receiving a pressure sensor 18a that detects the pressure Pa on the a side, a pressure Pa detected by the pressure sensor 18a, and a command pressure applied from the main controller 17 as described later. A first control valve controller 19a for controlling, a pressure sensor 18b for detecting a pressure Pb on the inflow / outflow port 1b side of the hydraulic motor 1,
It is provided with a second control valve controller 19b that drives and controls the electromagnetic proportional flow rate control valve 6b by receiving a pressure Pb detected by the pressure sensor 18b and a command pressure applied from the main controller 17 as described later. . Each control valve controller 19a, 19b is composed of an electronic circuit. Each control valve controller 19b, 19b
Are electromagnetic proportional flow control valves 6 so that the pressures Pa and Pb detected by the pressure sensors 18a and 18b respectively match the command pressure applied from the main controller 17.
The opening areas of a and 6b are adjusted.

The pump control device 16 includes a pressure sensor 20 for detecting the discharge pressure Po of the hydraulic pump 4 and the pressure sensor 2.
A pump controller 22 that controls the displacement of the hydraulic pump 4 via a regulator 21 in response to a discharge pressure Po detected by 0 and a command pressure on the inflow side of the hydraulic motor 1 given from a main controller 17 as described later. Is equipped with. The pump controller 22 is composed of an electronic circuit, and the pressure sensor 2 will be described in detail later.
The discharge pressure Po detected by 0 is the main controller 1
The capacity of the hydraulic pump 4 is controlled via the regulator 21 so as to be larger than the command pressure on the inflow side of the hydraulic motor 1 applied from 7 by a constant value.

The main controller 17 is composed of an electronic circuit including a microcomputer,
As its functional configuration, as shown in FIG. 2, a switching valve drive unit 23 that switches and drives the directional switching valve 5 according to the operating direction of the operating lever 12 detected by the operating amount detector 13,
A target speed setting unit 24 (target speed setting means) for setting a target turning speed Nr of the upper swing body 2 in accordance with the operation amount R of the operation lever 12 detected by the operation amount detector 13.
Target turning speed N set by the target speed setting unit 24
r and the inflow / outflow port 1 of the hydraulic motor 1 according to the revolving speed N of the upper revolving superstructure 2 detected by the speed sensor 14.
The pressure difference between a and 1b is set, and the command pressures on the inflow / outflow port 1a side and the inflow / outflow port 1b side of the hydraulic motor 1 for obtaining the set pressure difference are set to the control valve controllers 19a and 19b. The differential pressure setting unit 25 (differential pressure setting means) applied to the control lever 12 and the operation amount R of the operation lever 12 detected by the operation amount detector 13 are R = 0, and the speed sensor 14
And a valve closing command unit 26 which gives a command to close the electromagnetic proportional flow rate control valves 6a, 6b to the control valve controllers 19a, 19b when the turning speed N of the upper swing body 2 detected by N is 0. Is equipped with. Here, according to the configuration of the present invention, the valve closing command unit 26, the control valve controller 19
The valves a, 19b and the electromagnetic proportional flow rate control valves 6a, 6b constitute the closing means 27.

Although the details of these functional configurations of the main controller 17 will be described later, the differential pressure setting unit 25 includes a target turning speed Nr set by the target speed setting unit 24 and an upper portion detected by the speed sensor 14. A proportional-integral calculation unit 25a (proportional-integral calculation means) that performs a proportional-integral calculation of a deviation (Nr-N) from the revolving speed N of the revolving structure 2 is provided.

Next, the operation of such a device will be described.

First, when the upper swing body 2 of the hydraulic excavator is normally swung, the operating lever 12 is swung from its neutral position to the right in FIG. 1, for example.
The operation direction and the operation amount R are detected by the operation amount detector 13, and the detection signal is given to the main controller 17.

At this time, the switching valve drive section 23 of the main controller 17 switches the directional switching valve 5 from ON to OFF in the ON / OFF position in response to the operation of the operating lever 12 to the right. As a result, the pressure oil discharged from the hydraulic pump 4 is supplied to the hydraulic motor 1 via the direction switching valve 5 and the electromagnetic proportional flow rate control valve 6a as described above, and the hydraulic motor 1 further supplies the electromagnetic proportional flow rate control unit 6b. Then, the oil is collected in the oil tank 7 via the direction switching valve 5, and the hydraulic motor 1 rotates to drive the upper swing body 2 to rotate rightward, and the upper swing body 2 starts rotating rightward.

At this time, the target speed setting unit 24 of the main controller 17 is operated by the operation lever 1 as shown in FIG.
The target swing speed Nr of the upper swing body 2 with respect to the operation amount R of 2 (hereinafter referred to as the lever operation amount R) is provided in advance, and according to the map, it corresponds to the lever operation amount R currently detected. The target turning speed Nr is set. In this case, the target turning speed Nr is set to be larger as the lever operation amount R is larger, and the increase rate of the target turning speed Nr to the lever operation amount R is set to be larger as the lever operation amount R is larger. R.

The target turning speed Nr set by the target speed setting unit 24, together with the actual turning speed N of the upper turning body 2 detected by the speed sensor 14 at the present time, is the differential pressure setting unit 25 of the main controller 17. Given to. At this time, the proportional-plus-integral calculation unit 25a of the differential pressure setting unit 25 performs proportional-plus-integral calculation on the deviation (Nr-N) between the target turning speed Nr and the actual turning speed N according to the following equation (1),
A control calculation value X for so-called proportional integral control (PI control) is obtained.

[0034]

[Equation 1]

In the equation (1), k is a proportional gain, T is an integration time, the first term on the right side is a proportional term, and the second term is an integral term. In the present embodiment, the equation (1) for obtaining the control calculation value X has a turning speed N of, for example, N ≧ 1 [rp
m] and the turning speed N is substantially equal to zero N
In the case of <1 [rpm], the control calculation value X is obtained by using an equation different from the equation (1). Here, N ≧ 1 [rpm]
], And the case of N <1 [rpm] will be described later.

The differential pressure setting unit 25, which has obtained the control calculation value X as described above, sets the differential pressure between the inflow / outflow ports 1a and 1b of the hydraulic motor 1 according to the control calculation value X.

More specifically, the differential pressure setting unit 25 is shown in FIG.
As shown in, the command pressure Pas on the inflow / outflow port 1a side of the hydraulic motor 1 (in the case of a right turn, the inflow side of the hydraulic motor 1)
And a command pressure Pbs on the inflow / outflow port 1b side of the hydraulic motor 1 (in the case of a right turn, the outflow side of the hydraulic motor 1) are provided in advance with respect to a control calculation value X. The command pressures Pas and Pbs on the inflow / outflow port 1a side and the inflow / outflow port 1b side of the hydraulic motor 1 are set according to the currently calculated control calculation value X. As a result, the inflow / outflow port 1 of the hydraulic motor 1
The differential pressure between a and 1b is the difference between the command pressure Pas and Pbs (Pas-P
bs) will be set.

In this case, when the control calculation value X is a positive value, that is, when the actual turning speed N is smaller than the target rotation speed Nr, the command pressure Pas increases in proportion to the control calculation value X. And the command pressure Pbs is set to "0". As a result, the differential pressure between the inflow / outflow ports 1a and 1b of the hydraulic motor 1 is set to increase in proportion to the control calculation value X in the direction in which the drive torque of the hydraulic motor 1 increases toward the speed increasing side. It Also, the control calculation value X
Is a negative value, that is, when the actual turning speed N is higher than the target rotation speed Nr, the command pressure Pas is set to "0" and the command pressure Pbs is the control calculation value, contrary to the above case. It is set to increase in proportion to X. Accordingly, the differential pressure between the inflow / outflow ports 1a and 1b of the hydraulic motor 1 is set to increase in proportion to the control calculation value X in the direction in which the driving torque of the hydraulic motor 1 increases toward the deceleration side. .

After reaching the maximum pressure Pmax of the overload relief valve 11 (see FIG. 1), the command pressures Pas and Pbs are set to the maximum pressure Pmax regardless of the control calculation value X. .

The command pressures Pas and Pbs set by the differential pressure setting unit 25 according to the present control calculation value X are given to the control valve controllers 19a and 19b, respectively. At this time, the control valve controllers 19a and 19b are operated by the pressure Pa detected by the pressure sensors 18a and 18b, respectively.
Pb is a command pressure P applied from the main controller 17
Each electromagnetic proportional flow control valve 6a, 6b so as to be as, Pbs
Adjust the opening area of.

Specifically, when turning right, the control valve controller 19a determines that the opening area of the electromagnetic proportional flow rate control valve 6a is small when the pressure Pa detected by the pressure sensor 18a is smaller than the command pressure Pas. The electromagnetic proportional flow rate control valve 6a is driven so as to increase, in other words, weaken the throttle of the electromagnetic proportional flow rate control valve 6a, and the pressure Pa on the inflow / outflow port 1a side of the hydraulic motor 1 is increased. Also,
The pressure Pa detected by the pressure sensor 18a is the command pressure P
If it is larger than as, the control valve controller 19a
Drives the electromagnetic proportional flow rate control valve 6a so that the opening area of the electromagnetic proportional flow rate control valve 6a becomes small, in other words, strengthens the throttle of the electromagnetic proportional flow rate control valve 6a, and the inflow of the hydraulic motor 1 The pressure Pa on the outflow port 1a side is reduced. Further, the control valve controller 19b is used for the pressure sensor 1
When the pressure Pb detected by 8b is smaller than the command pressure Pbs, the electromagnetic proportional flow rate control valve 6b is driven so that the opening area of the electromagnetic proportional flow rate control valve 6b becomes small, and the inflow / outflow of the hydraulic motor 1 is performed. The pressure Pb on the port 1b side is increased. In addition, the pressure P detected by the pressure sensor 18b
When b is larger than the command pressure Pbs, the control valve controller 19b drives the electromagnetic proportional flow control valve 6b so that the opening area of the electromagnetic proportional flow control valve 6b becomes large, and the inflow / outflow of the hydraulic motor 1 is performed. The pressure Pb on the port 1b side is reduced. As a result, the differential pressure (Pa-Pb) between the inflow / outflow ports 1a and 1b of the hydraulic motor 1 is set to the differential pressure setting unit 2 described above.
The differential pressure (Pas-Pbs) set by 5 is controlled.

In parallel with this operation, of the command pressures Pas, Pbs set by the differential pressure setting unit 25 according to the present control calculation value X, the command pressure Pas, on the inflow side of the hydraulic motor 1 is Pbs (command pressure Pas in the case of right turn) is given to the pump controller 22. At this time, the pump controller 22 determines that the discharge pressure Po of the hydraulic pump 4 detected by the pressure sensor 20 is the main controller 17. The capacity of the hydraulic pump 4 is controlled via the regulator 21 so as to be larger than the inflow-side command pressure Pas of the hydraulic motor 1 given by the above. As a result, the flow rate of the pressure oil from the hydraulic pump 4 to the hydraulic motor 1 is ensured to be the flow rate necessary for rotationally driving the hydraulic motor 1.

The control and operation described above are similarly performed when the upper swing body 2 is turning to the left.

In the apparatus of this embodiment, basically,
The described control and operation are performed every moment, and the target turning speed N
r and the actual swing speed N of the upper swing body 2 (Nr-
The differential pressure (Pa-Pb) between the inflow / outflow ports 1a and 1b of the hydraulic motor 1, in other words, the drive torque of the hydraulic motor 1 is controlled so that N) is reduced. That is, Nr
When> N, the differential pressure (Pa-Pb) between the inflow / outflow ports 1a and 1b of the hydraulic motor 1 is controlled to the differential pressure that accelerates the upper swing body 2, and Nr <N. At times, the differential pressure (Pa-Pb) is controlled to a differential pressure such that the upper swing body 2 decelerates. And, in particular, the integral term of the equation (1) for obtaining the control calculation value X is the deviation (Nr-
N) is solved so that the actual swing speed N of the upper swing body 2 surely matches the target swing speed Nr determined according to the lever operation amount R.

The inflow / outflow port 1 of the hydraulic motor 1
The differential pressure (Pa-Pb) between a and 1b is the deviation (Nr-N)
Is controlled so as to increase in proportion to this, the higher the operating speed when the operating lever 12 is operated from one operating position to another operating position, the faster the differential pressure (Pa- Pb), in other words, the driving torque of the upper swing body 2 by the hydraulic motor 1 becomes large, the acceleration of the upper swing body 2 becomes large, and the operating lever 1
The acceleration / deceleration of the upper swing body 2 according to the operation speed of 2 can be obtained.

For example, as shown in FIG. 5, when the target turning speed Nr corresponding to the lever operation amount R changes, the actual turning speed N of the upper turning body 2 changes following the target turning speed Nr. In a state where the target turning speed Nr is kept constant by holding the operation lever 12 at a position of a certain lever operation amount R, the actual turning speed N of the upper turning body 2 is made to match the target turning speed Nr. Further, when the target turning speed Nr is increased / decreased by changing the lever operation amount R, the actual turning speed N of the upper swing body 2 also increases / decreases following the increase / decrease in the target turning speed Nr.

Further, as shown in FIG. 6A, when the load of the upper revolving superstructure 2 changes while the lever operation amount R is kept constant, the actual revolving speed N of the upper revolving superstructure 2 is changed.
As shown in FIG. 6 (b), although it temporarily changes when the load fluctuates, it rapidly changes to match the target turning speed Nr corresponding to the lever operation amount R.

Thus, in the apparatus of this embodiment,
The differential pressure (Pa-Pb) of the hydraulic motor 1 is controlled so that the deviation (Nr-N) between the target swing speed Nr according to the lever operation amount R and the actual swing speed N of the upper swing body 2 is reduced. ,
Further, the deviation (Nr-N) is large, and the control calculation value X
The larger the value is, the larger the differential pressure (Pa-Pb) of the hydraulic motor 1 is controlled, so that the target turning speed Nr corresponding to the lever operation amount R can be quickly and reliably obtained, and the operation lever 12 can be operated. Upper revolving structure 2 according to operating speed
The acceleration / deceleration of can be obtained.

As shown in FIG. 3, the larger the lever operation amount R, the larger the rate of increase of the target turning speed Nr with respect to the lever operation amount R becomes.
Is set, the target turning speed N with respect to the change in the lever operation amount R is set in a range in which the lever operation amount R is relatively small.
Since the change width of r is small, the fine swing operation of the upper swing body 2 can be easily performed.

The proportional gain k and the integration time T in the equation (1) are instantaneously changed from the neutral position of the operating lever 12 to the maximum operating amount R, that is, the differential pressure setting unit 25. When a step input of the maximum target swing speed Nr is given to the, the proportional gain k and the integral are set so that the swing speed N of the upper swing body 2 causes, for example, about 10% overshoot with respect to the maximum target swing speed Nr. Set time T. Thus, the proportional gain k and the integration time T
By setting, the following property of the turning speed N with respect to the target turning speed Nr becomes relatively good at an arbitrary turning speed N of the upper swing body 2.

It is needless to say that the proportional gain k and the integration time T in the equation (1) can be set according to the turning speed N of the upper turning body 2, for example.

Next, the pressing work by the turning motion of the upper-part turning body 2 will be described.

When performing the pressing work, the turning speed N of the upper turning body 2 is N≈, regardless of the value of the target turning speed Nr.
Since it becomes 0, the deviation (Nr-N) does not become "0". Therefore, when the control calculation value X is obtained by the equation (1), the integral term of the equation (1) increases every moment. . Therefore, the differential pressure (Pa-Pb) of the hydraulic motor 1 is ultimately the maximum pressure of the overload relief valve 11 (see FIG. 1) regardless of the value of the target turning speed Nr according to the lever operation amount R. Therefore, the torque of the hydraulic motor 1 is also maintained at the maximum torque.

Therefore, in the present embodiment, the proportional-plus-integral calculation unit 25a of the differential pressure setting unit 25 has N≈0, N <0.
At 1 [rpm], the control calculation value X is obtained by the following equation (2) using the integral term of the equation (1) as a fixed value.

X = k (Nr-N) + Co (2) where N <1 [rpm] In the above equation (2), Co is a fixed value. As is clear from the equation (2), since N≈0, the control calculation value X is proportional to the target turning speed Nr as shown in FIG. 7, and therefore the control calculation value X is set as described above. The differential pressure (Pa-Pb) of the hydraulic motor 1 to be changed also changes in proportion to the target turning speed Nr.

As a result, during the pressing work with N≈0, the torque of the hydraulic motor 1 changes in accordance with the lever operation amount R, and the operator appropriately adjusts the lever operation amount R to make an upper turn. The pressing force due to the turning motion of the body 2 can be made a desired pressing force. The fixed value Co is, for example, the differential pressure (Pa-P) of the hydraulic motor 1.
b) is set to a value such that it is the minimum driving pressure when the upper swing body 2 is unloaded. By doing so, it is possible to prevent the upper swing body 2 from wobbling when the lever operation amount R is relatively small.

In the apparatus of this embodiment, when the operation position of the operation lever 12 is the neutral position (when the lever operation amount R = 0), the target turning speed Nr is "0". As described above, the differential pressure (Pa−
By controlling Pb), basically, the swing speed N of the upper swing body 2 is controlled to be "0", but if the load changes, the upper swing body 2 slightly fluctuates. . On the other hand, when the operating position of the operating lever 12 is held at the neutral position and the turning speed N is N≈0,
Since there is a case where the stop of the upper swing body 2 is required, it is preferable to keep the swing speed N of the upper swing body 2 completely "0".

Therefore, in the apparatus of this embodiment, the lever operation amount R is R = 0 and the swing speed N of the upper swing body 2 is N.
Is N≈0 (for example, N <1 [rpm]), the valve closing command unit 2 of the main controller 17
Reference numeral 6 gives a command to close the electromagnetic proportional flow rate control valves 6a and 6b to the control valve controllers 19a and 19b. At this time, the control valve controllers 19a and 19b close the electromagnetic proportional flow rate control valves 6a and 6b regardless of the command from the differential pressure setting unit 25. As a result, the inflow / outflow ports 1a and 1b of the hydraulic motor 1 are closed, so that the hydraulic motor 1 cannot rotate, and therefore the revolving speed N of the upper revolving superstructure 2 is maintained at N = 0. .

In the above-described embodiments, the control of the hydraulic motor 1 is described as an example, but the present invention can be applied to other actuators such as boom cylinders, arm cylinders and bucket cylinders of hydraulic excavators. Of course it is possible.

Further, in the present embodiment, the control calculation value X is obtained by using the proportional-plus-integral calculation of the equation (1), and the differential pressure (Pa-Pb) of the hydraulic motor 1 is so-called proportional-integral control (PI control). It is controlled by the equation (1)
It goes without saying that it is possible to add a differential term to control the differential pressure (Pa-Pb) of the hydraulic motor 1 by so-called proportional-plus-integral-derivative control (PID control).

[0061]

As is apparent from the above description, according to the present invention, the target operating speed of the actuator is set according to the operation amount of the operating lever, and the target operating speed and the actual operating speed of the actuator are set. The differential pressure between the inlet and the outlet of the actuator is controlled by proportional-plus-integral control so as to eliminate the deviation between the two, and the greater the calculated value of proportional-plus-integral, the greater the differential pressure. Thus, the operating speed of the actuator corresponding to the operation amount of the operating lever can be quickly obtained, and the acceleration / deceleration when changing the operating speed of the actuator can be controlled through the operation of the operating lever.

Then, when the actual operating speed of the actuator is a low speed which is substantially zero, the calculated value of the proportional integral is obtained by setting the integral term of the proportional integral calculation to a predetermined fixed value. When performing work or the like, the driving force of the actuator can be controlled by operating the operation lever.

Further, by setting the target operating speed such that the increase rate of the target operating speed with respect to the operating amount of the operating lever becomes larger as the operating amount of the operating lever increases, the operating amounts of the operating levers are compared. Within a relatively small range, the change in the operating speed of the actuator with respect to the change in the operation amount can be made small, and the fine speed operation of the actuator can be easily performed.

Further, when the operating speed of the actuator is substantially zero and the operation amount of the operating lever is substantially zero, the pressure oil inflow path and outflow path of the actuator are closed so that the operation lever is closed. When is held at the neutral position, the actuator can be reliably held in the stopped state.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an example of a hydraulic control device for a work machine according to the present invention.

FIG. 2 is a block configuration diagram of a main part of the apparatus shown in FIG.

FIG. 3 is a diagram for explaining the operation of the device of FIG.

FIG. 4 is a diagram for explaining the operation of the apparatus of FIG.

FIG. 5 is a diagram for explaining the operation of the apparatus of FIG.

FIG. 6 is a diagram for explaining the operation of the apparatus of FIG.

FIG. 7 is a diagram for explaining the operation of the device of FIG.

[Explanation of symbols]

1 ... hydraulic motor (actuator), 4 ... hydraulic pump,
12 ... Operation lever, 13 ... Operation amount detector (operation amount detection means), 14 ... Speed sensor (speed detection means), 15 ... Pressure control device (pressure control means), 24 ... Target speed setting unit (target speed setting means) ), 25 ... Differential pressure setting section (differential pressure setting means), 25a ... Proportional integral calculation section (proportional integral calculation means),
27 ... Blocking means.

Claims (4)

[Claims] 1. A hydraulic control device for a working machine, wherein hydraulic oil is supplied from a hydraulic pump to an actuator to drive the actuator in response to an operation of an operating lever, and speed detection means for detecting an operating speed of the actuator; Operation amount detection means for detecting an operation amount of the operation lever, target speed setting means for setting a target operation speed of the actuator according to the operation amount of the operation lever detected by the operation amount detection means, and the target speed According to the deviation between the target operating speed set by the setting means and the operating speed of the actuator detected by the speed detecting means, the deviation of the differential pressure between the pressure oil inlet and the outlet of the actuator is eliminated. Direction differential pressure setting means, and the pressure oil flow of the actuator to obtain the differential pressure set by the differential pressure setting means. Pressure control means for controlling the pressure of the mouth and the outlet, the differential pressure setting means, a proportional term obtained by multiplying a deviation between the target operating speed and the operating speed of the actuator by a predetermined proportional gain; The differential pressure is set to a larger value as the calculated value obtained by the calculating means is larger, and the proportional-integral calculating means calculates a total sum with the integral term formed by integrating the deviation within a predetermined integration time. A hydraulic control device for a working machine, characterized by: 2. The proportional-plus-integral calculation means sets the integral term as a predetermined fixed value when the operating speed of the actuator detected by the speed detecting means is a low speed which is substantially zero. The hydraulic control device for a working machine according to claim 1, wherein a sum total of and is calculated. 3. The target speed setting means sets the target operating speed such that the increase rate of the target operating speed with respect to the operating amount of the operating lever increases as the operating amount of the operating lever increases. The hydraulic control device for a working machine according to claim 1, which is characterized in that. 4. The actuator when the operating speed of the actuator detected by the speed detecting means is substantially zero and the operation amount of the operation lever detected by the operation amount detecting means is substantially zero. The hydraulic control device for a working machine according to claim 1, further comprising a closing unit that closes an inflow path and an outflow path of the pressure oil.