JPH0641764B2 - Drive control device for hydraulic circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for a hydraulic circuit in which a single hydraulic pump drives a plurality of actuators by means of a parallel circuit, and particularly to a hydraulic circuit suitable for civil engineering construction machines. Drive controller.

[Conventional technology]

A hydraulic system in which one hydraulic pump is used as a hydraulic source and a plurality of hydraulic actuators are driven by parallel circuits is used in many fields. In such a hydraulic system, each hydraulic actuator operates its own load, but when these loads are operated simultaneously (during compound operation), more oil is supplied to the actuator operating a lighter load. Occurs and the speed thereof is increased, and the flow rate to the actuator operating the heavy load is decreased, and the speed thereof is decreased. When this phenomenon becomes extreme, the actuator that operates a heavy load cannot be driven even though it is in the operating state by operating the operating lever or the like.

Such a situation often occurs especially in civil engineering and construction machines where there is a considerable difference in the magnitude of the load on the actuator. For example, in a hydraulic shovel, in the case of a hydraulic system in which a single hydraulic pump drives an arm cylinder and a swing motor by a parallel circuit, pressure oil from the hydraulic pump flows into an arm cylinder with a small load during combined operation of the two. In some cases, only the arm cylinder is driven and the swing motor is not driven.

To prevent the occurrence of this situation, conventionally, a throttle is inserted in the flow path of the actuator that operates a light load, or the actuator is given a priority order and the operation control according to this priority order is performed during combined operation, Alternatively, another hydraulic pump has been incorporated into the circuit during complex operation, or so-called load sensing type load compensating means has been adopted.

[Problems to be Solved by the Invention]

However, the means using a diaphragm increases the loss of the circuit,
Also, the responsiveness of the actuator is deteriorated, and the means for performing operation control with prioritization has a complicated structure.In addition, the means for incorporating other hydraulic pumps in the circuit requires the installation of a separate hydraulic pump. The load compensating means of the method has a problem that the valve structure is complicated and it is impossible to compensate the loads of a plurality of actuators. Further, none of these means can obtain a sufficient effect for preventing the occurrence of the above situation.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a drive control device of a hydraulic circuit which has a simple configuration and can drive each actuator according to the operation even in a combined operation.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a hydraulic pump,
In a hydraulic circuit including a plurality of hydraulic actuators connected to this hydraulic pump by a parallel circuit, and a switching valve for controlling the drive of each hydraulic actuator, a first pressure detection for detecting the discharge pressure of the hydraulic pump. And a second pressure detector for detecting an inlet pressure of a hydraulic actuator to be controlled among the hydraulic actuators, and a detection pressure of each of the first pressure detector and the second pressure detector. Operation means for calculating the differential pressure, operation command value of the hydraulic actuator to be controlled, and operation command value of the hydraulic actuator to be controlled with respect to the sum of this operation command value and operation command values of other hydraulic actuators. The means for determining the flow rate that should flow into the hydraulic actuator to be controlled based on the ratio of And wherein by providing the opening area control means for controlling an opening area of the switching valve of the hydraulic actuator serving as the control target on the basis of the pressure difference obtained by the fit obtained flow rate and the calculation means.

[Operation] When operating the hydraulic actuators in combination, the operation command of the hydraulic actuators to be controlled with respect to the sum of the operation command values of the hydraulic actuators to be controlled and the respective operation command values of all hydraulic actuators to be compositely operated. The flow rate that should flow into the hydraulic actuator to be controlled is calculated based on the ratio of the values, and the control is performed based on this flow rate and the differential pressure between the discharge pressure of the hydraulic pump and the inlet pressure of the hydraulic actuator to be controlled. The opening area of the switching valve of the target hydraulic actuator is controlled.

〔Example〕

 Hereinafter, the present invention will be described based on the illustrated embodiments.

FIG. 1 is a system diagram of a control device for a hydraulic shovel according to an embodiment of the present invention. In the figure, 1 is a variable displacement hydraulic pump,
Reference numeral 1a is a variable displacement mechanism for the hydraulic pump 1, and 2 is a regulator for operating the variable displacement mechanism 1a.
Reference numeral 3 denotes a turning hydraulic motor that turns the upper turning body of the hydraulic shovel (hereinafter, simply referred to as a turning motor). Reference numeral 4 denotes a turning direction switching valve that controls driving of the turning motor 3. Reference numeral 5 is an arm cylinder that drives an arm in the front structure of the hydraulic shovel, and reference numeral 6 is an directional valve for an arm that controls the drive of the arm cylinder 5.

The swing motor 3 and the arm cylinder 5 are connected to the hydraulic pump 1 in parallel with each other. Further, both the turning direction switching valve 4 and the arm direction switching valve 6 are center-closed type direction switching valves whose opening area can be controlled.

Reference numeral 7 is a relief valve that regulates the maximum discharge output of the hydraulic pump 1. 8A is a command signal X according to the operation of the arm lever
It is an operation command signal generator for the arm that outputs _LA . or,
Reference numeral 8S is a turning operation command signal generator which outputs a command signal X _LS according to the operation of the turning lever. 9 is a hydraulic pump 1
Is a pressure sensor that detects the discharge pressure, 10 is a pressure sensor that detects the pressure of the swing motor 3, and 11 is a pressure sensor that detects the pressure of the arm cylinder 5. Reference numeral 12 denotes an arm operation command signal generator 8A, a turning operation command signal generator 8S, and signals of the respective pressure sensors 9, 10, 11 to input necessary calculations and control, and a turning direction switching valve 4 and an arm. It is a control unit that controls the direction switching valve 6 and the regu- lator 2.

In the present embodiment, attention is paid to an example in which the swing motor 3 of the hydraulic shovel and the arm cylinder 5 are connected in parallel, so that illustration of other actuators of the hydraulic shovel is omitted.

FIG. 2 is a block diagram of a part of the control unit shown in FIG. The control system for the regulator 2 is not shown in the figure. In the figure, reference numeral 15 denotes a switching element which is switched according to the switching direction of the arm directional control valve 6, and by this switching, a detection signal P _A from the pressure sensor 11 in the pipeline on the side that supplies the pressure oil to the arm cylinder 5 is detected. Is entered. Reference numeral 16 denotes an adder, which adds the detection signal P _P (the discharge pressure of the hydraulic pump 1) from the pressure sensor 9 and the detection signal P _A whose sign is reversed. The output signal ΔP of the adder 16 becomes the signal of the difference between the detection signals P _P and P _A.

Reference numeral 17 is a function generator for obtaining the flow rate Q to be supplied to the arm cylinder 5 corresponding to the command signal X _LA output from the arm operation command signal generator 8A. 18 inputs the output signal X _LA of the arm operation command signal generator 8A and the output signal X _{LS of the} turning operation command signal generator 8S, and the ratio of the output signal X _LA to the total value of the respective output signals, That is, X _LA
This is a calculation unit that calculates / (X _LA + X _LS ). Reference numeral 19 is a multiplier that multiplies the flow rate Q output from the function generator 17 by the value output from the calculation unit 18. Reference numeral 20 is an arithmetic unit for inputting the value Q ′ output from the multiplier 19 and the value ΔP output from the adder 16 and performing a required operation. In this calculation unit 20, the opening area A of the arm directional control valve 6 is obtained by the following calculation.

Here, c: flow coefficient g: acceleration of gravity γ: specific weight. Reference numeral 21 is a function generator, which is a directional control valve 6 for the arm.
The stroke L of the directional control valve 6 for the arm for making the opening area of the opening area of the opening area obtained by the calculation unit 20 is obtained. twenty two
Is a switching valve command signal output mechanism that outputs a command signal to the arm directional switching valve 6 so that the stroke L obtained by the function generator 21 is achieved.

Next, the operation of this embodiment will be described. First, the swing motor 3
In the case where is operated independently, when the turning lever is operated, the signal X _LS is output from the turning operation command signal generator 8S in response thereto. In the control unit 12, calculated on the basis of the signals X _LS by a controller (not shown), performs control to drive the Regiyureta 2 accordingly. Then, the swing motor 3 is
The hydraulic pump 1 is driven at a speed according to the discharge amount of the hydraulic pump 1 according to the drive of the regu- lator 2 and the input torque control of the hydraulic pump 1 by a control unit (not shown). In this case, the turning direction switching valve 4 is operated in a substantially full stroke.

On the other hand, when the arm cylinder 5 is independently operated, when the operation lever is operated, the signal X _LA is output from the arm operation command signal generator 8A in response to this, and the flow rate Q corresponding to this is output by the function generator 17. Is required. On the other hand, in this case, the signal X _LS is 0, so the output of the calculation unit 18 is 1. Therefore, the output Q'of the multiplier 19 becomes Q '= Q. The calculation unit 20 calculates the opening area A of the directional control valve 6 for the arm according to the equation (1) based on this value Q'and the pressure difference ΔP between the pressures detected by the pressure sensors 9 and 11. In the function generator 21, a stroke L of the arm directional control valve 6 corresponding to the opening area A is obtained, and this stroke L is output to the arm directional control valve 6 via the switching valve command signal output mechanism 22. By driving the stroke L, the opening area of the arm directional control valve 6 is set to a value A corresponding to the signal X _LA .

Next, a case where a combined operation of the turning motor 3 and the arm cylinder 5, that is, a case where the arms are simultaneously driven while turning the front mechanism of the hydraulic shovel will be described. In this case, in this embodiment, the actuator to be controlled is an arm cylinder, and the opening area of the arm directional control valve 6 that controls the drive of the arm cylinder is controlled by the configuration shown in FIG. In the case of such a combined operation, in the conventional device, assuming that the opening areas of the turning direction switching valve 4 and the arm direction switching valve 6 are the same as those in the case of the single operation, generally, the load of the turning motor 3 is the arm. Since the load of the cylinder 5 is larger than the load of the hydraulic pump 1, the discharge oil of the hydraulic pump 1 flows into the arm cylinder 5 having a small load, and the discharge pressure of the hydraulic pump 1 does not rise until the swing motor 4 can be driven. Therefore, only the arm cylinder 5 is driven and the swing motor 4 cannot be driven.

However, in this embodiment, since the control device 12 is provided with the means shown in FIG. 2, the arm cylinder 5 and the turning motor 4 can be driven simultaneously. That is, during composite operation, the signal X _LA from the arm operation command signal generator 8A is
Further, the signal X _LS from the turning operation command signal generator 8S is simultaneously input to the control device 12. The function generator 17 outputs the flow rate Q according to the input signal X _LA . On the other hand, the calculation unit 18
The signal X _LA distribution ratio of the signal X _LA in the signal X _LS X _LA /
(X _LA + X _LS ) is calculated, and the flow rate Q is multiplied by this ratio by the multiplier 19 to obtain a new flow rate Q ′. The flow rate Q ′ is a value obtained by dividing the flow rate Q by the distribution ratio of the signal X _LA and the signal X _LS . Therefore, the flow rate Q'is lower than the flow rate Q when the arm cylinder 5 is operated alone.

In the calculation unit 20, based on the flow rate Q ′ and the differential pressure ΔP,
The opening area A of the arm directional control valve 6 is calculated by the equation (1), and thereafter, the function generator 21 and the directional control valve command signal output mechanism 22 as in the case of the independent operation of the arm cylinder 5 described above.
The opening area of the arm directional control valve 6 is controlled to the calculated value A via.

As a result, even if the value of the signal X _LA is equal to the value when the arm cylinder 5 is operated independently, the opening area of the arm directional control valve 6 is smaller than the opening area when the arm cylinder 5 is operated independently. The aperture is set. That is, the state is the same as when the throttle is inserted in the input pipe of the arm cylinder 5. As a result, the discharge pressure of the hydraulic pump 1 increases,
The swing motor 3 is also driven simultaneously with the arm cylinder 5.

As described above, in this embodiment, the opening area of the arm directional control valve is controlled according to the distribution ratio of the manipulated variables during the combined operation, so that the swing motor and the arm cylinder connected in parallel are respectively The same drive can be performed with a flow rate that is faithful to their distribution ratio based on the operation command value of. Further, since the opening area of the arm directional control valve is controlled by the differential pressure, it is possible to prevent the speed of the swing motor and the arm cylinder from changing even if the discharge pressure of the hydraulic pump changes during the combined operation. . Further, even if the pressure changes due to the load, the speeds of the swing motor and the arm cylinder do not change.

In the above description of the embodiment, the parallel circuit of the swing motor of the hydraulic shovel and the arm cylinder has been described, but the present invention is not limited to this example, and may be applied to the parallel circuit of various actuators in various machines. In addition, the number of actuators connected in parallel is not limited to two, and may be three or more.
Further, in the above description of the embodiment, the means for controlling the opening area is provided only for the arm directional control valve, but it may be provided for the turning directional control valve. In general, when there are a plurality of actuators, the load of each actuator can be considered, and all or any of the directional control valves can be provided with the means. Furthermore, the control unit can be configured by a micro computer, and in this case,
Obviously, each function generator will consist of a memory.

〔The invention's effect〕

As described above, in the present invention, the operation command value of the actuator to be controlled among the plurality of actuators connected in parallel to one hydraulic pump, and this operation command value and the operation command values of other actuators. Based on the ratio of the operation command value of the hydraulic actuator to be controlled to the total of the above, the flow rate to be flown into the actuator to be controlled is calculated, and the calculated flow rate, the discharge pressure of the hydraulic pump and the control target Since the opening area of the switching valve of the actuator to be controlled is controlled based on the pressure difference with the actuator pressure, the actuators can be distributed based on their operation command values even during complex operation. It can be driven simultaneously with a flow rate faithful to the ratio. Further, in principle, all the actuators can be connected in parallel, so that the circuit itself becomes simple and it becomes easy to add other control means. Further, since the opening area of the switching valve is controlled by the differential pressure, even if the discharge pressure of the hydraulic pump changes during the combined operation, it is possible to suppress the change in the speed of each actuator. Further, the control of this switching valve does not change the speed of the actuator even if the load pressure changes.

[Brief description of drawings]

FIG. 1 is a system diagram of a hydraulic shovel control device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a part of the control unit shown in FIG. 1 ... hydraulic pump, 3 ... swing motor, 4 ... slewing direction switching valve, 5 ... arm cylinder, 6 ... arm direction switching valve, 8A ... arm operation command signal generator, 8S ...
… Turning operation command signal generator, 9,10,11 …… Pressure sensor, 12 …… Control unit, 16 …… Adder, 17,21 …… Function generator, 18,20 …… Calculation unit, 19… … Multiplier, 22 …… Switching valve command signal output mechanism

Front Page Continuation (72) Inventor Tomohiko Yasuda 650 Kazunachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura Plant (56) References JP-A-60-11706 (JP, A) JP-A-61-79003 (JP, A)

Claims (2)

[Claims] Claim: What is claimed is: 1. A hydraulic circuit comprising a hydraulic pump, a plurality of hydraulic actuators connected to the hydraulic pump by a parallel circuit, and a switching valve for controlling the drive of each of the hydraulic actuators. A first pressure detector for detecting a pressure, a second pressure detector for detecting an inlet pressure of a hydraulic actuator to be controlled among the hydraulic actuators, the first pressure detector and the second pressure detector. Calculating means for calculating the differential pressure between the respective detected pressures of the pressure detector, the operation command value of the hydraulic actuator to be controlled, and the control for the sum of this operation command value and the operation command value of another hydraulic actuator. Based on the ratio of the operation command value of the target hydraulic actuator, find the flow rate that should flow into the target hydraulic actuator. And an opening area control means for controlling the opening area of the switching valve of the hydraulic actuator to be controlled based on the flow rate obtained by this means and the differential pressure obtained by the calculating means. Drive control device for hydraulic circuit. 2. The opening area control means according to claim 1, wherein the opening area control means determines the flow rate to be flown into the hydraulic actuator to be controlled and the difference obtained by the calculation means. The other calculation means for calculating the opening area of the switching valve of the hydraulic actuator to be controlled based on the pressure, and the stroke of the switching valve to be controlled according to the opening area obtained by this other calculation means A drive control device for a hydraulic circuit, comprising: a function generator to be obtained and output means for instructing a switching valve to be controlled, the stroke obtained by the function generator.