JPH05272461A - Discharge control device for hydraulic pump - Google Patents

Abstract

PURPOSE:To control the discharge of a hydraulic pump accurately in the case of driving plural hydraulic actuators by one common hydraulic pump. CONSTITUTION:Individual discharge quantities q1-q6 by hydraulic actuators corresponding to the respective lever operating quantities s1-s6 of operating levers 21-26 are obtained by individual discharge computing means 31-36. On the basis of the sum of these individual discharge quantities q1-q6, a total discharge computing means 38 computes total discharge Q which is the actual pump discharge, and the inclined rotation angle of a hydraulic pump is controlled by a pump control solenoid proportional valve 42 so as to obtain this discharge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge amount control device for a hydraulic pump which commonly drives a plurality of hydraulic actuators in hydraulic excavators and other hydraulic machines.

[0002]

2. Description of the Related Art Generally, when a plurality of hydraulic actuators are simultaneously driven by a single hydraulic pump, if the discharge amount of the pumps is kept constant, a single hydraulic pump causes a single hydraulic actuator. As compared with the case where the hydraulic actuator is driven, the operating speed of the hydraulic actuator on the heavy load side decreases due to the magnitude of the load on each hydraulic actuator, and the operability deteriorates. Therefore, conventionally, the discharge amount control is performed so that the pump discharge amount corresponding to the operating state of each hydraulic actuator can be obtained.

FIG. 7 shows, by way of example, a system in which two hydraulic actuators are driven by a single hydraulic pump. In the figure, the hydraulic oil discharged from the hydraulic pump 90 passes through a line 93 and passes through a switching control valve 91.
hydraulic actuators 92 via a and 91b, respectively.
The remaining hydraulic oil is appropriately supplied to the tanks 94a and 92b and passes through a throttle valve 96 connected in parallel with the relief valve 95.
Be led to. At this time, on the upstream side of the throttle valve 96,
A pressure P ₁ is generated according to the throttle flow rate Q ₁ , but this pressure P ₁ is detected, and feedback control of the discharge amount Q ₀ of the hydraulic pump 90 is performed based on this pressure P _1. There is. Specifically, the relationship between the pressure P ₁ and the discharge amount Q ₀ is set as shown in FIG. 8, and the pump discharge amount Q ₀ is reduced as the pressure P ₁ increases. ing.

According to such a device, when the operating levers for the respective hydraulic actuators 92a, 92b are in the neutral position (that is, the respective hydraulic actuators 92a, 92b).
2b), the throttle flow rate Q ₁ becomes equal to the pump discharge amount Q ₀ , the pressure P ₁ becomes maximum, and the pump discharge amount Q ₀ is set to the minimum value. On the other hand, when one of the operation levers is operated to increase the flow rate of the hydraulic actuator 91a or 91b,
The throttle flow rate Q ₁ and the pressure P ₁ are decreased by the increased amount, and the pump discharge amount Q ₀ is automatically increased following the decrease.

[0005]

Since the above device changes the pump discharge amount Q _{0 in accordance} with the actual oil flow rate in the hydraulic actuators 92a and 92b, the appropriate discharge amount control can be performed by an external factor. May be disturbed. For example, when a large load acts on the hydraulic actuators 91a and 91b, the hydraulic actuators 91a and 91b
When the flow rate becomes 0 due to no operation, the throttle discharge flow rate Q ₁ and the pressure P ₁ are equal to those at the neutral time, even though the required flow rates of the hydraulic actuators 91a and 91b are large. The quantity Q ₀ is set to the minimum value, making proper control impossible.

Further, in such feedback control, the control value may not stabilize at the target value due to the response delay.

In view of the above circumstances, it is an object of the present invention to provide a device capable of accurately controlling the pump discharge amount when driving a hydraulic actuator.

[0008]

SUMMARY OF THE INVENTION The present invention is an apparatus for controlling the discharge rate of a variable displacement hydraulic pump that drives a plurality of hydraulic actuators in common, and an operation command for outputting an operation command signal for each hydraulic actuator. Means, an individual discharge amount calculation means for obtaining a necessary pump discharge amount for each hydraulic actuator corresponding to the operation command signal from the operation command means, and a sum of respective necessary discharge amounts obtained by the individual discharge amount calculation means. A total discharge amount calculating means for calculating the final required discharge amount of the hydraulic pump, and a discharge amount controlling means for controlling the actual discharge amount of the hydraulic pump based on the calculation result of the total discharge amount calculating means. (Claim 1).

Further, the number of hydraulic actuators is N,
When the minimum required pump discharge amount when all hydraulic actuators are stopped is q _min and the required discharge amount obtained by the individual discharge amount calculation means for the i-th hydraulic actuator is q i, the total discharge amount Q is calculated based on the following equation. By configuring the above-mentioned total discharge amount calculation means in such a manner, a more excellent effect as described below can be obtained (claim 2).

[0010]

[Equation 2]

[0011]

According to the apparatus of the first aspect, first, the individual discharge amount calculation means obtains the required pump discharge amount corresponding to the operation command signal from the operation command means for each actuator. Next, based on the sum of these individual discharge amounts, the final discharge amount of the hydraulic pump is calculated by the total discharge amount calculating means, and the actual discharge amount control of the hydraulic pump is performed based on this total discharge amount. ..

More specifically, according to the apparatus of claim 2, the minimum required pump discharge amount q _min from each individual discharge amount qi.
Is added to the sum of the amount (that is, the additional amount required to operate each hydraulic actuator) minus the minimum required pump discharge amount q _min , that is, the minimum pump discharge amount q _min required when all hydraulic actuators are stopped. Is set as the total discharge amount Q.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. Here, an example in which the device of the present invention is provided in a hydraulic excavator (backhoe) as shown in FIG. 6 is shown, but the present invention is widely applied to other cases where the discharge amount control of the hydraulic pump is performed in various hydraulic machines. Is possible.

The hydraulic excavator comprises a bucket 1, a boom 2, an arm 3, a link 4, a bucket cylinder (hydraulic actuator) 5, a boom cylinder (hydraulic actuator) 6, an arm cylinder (hydraulic actuator) 7, and a main body 8. There is.

The boom 2 has its base end mounted on the main body 8 and is rotated about a horizontal axis by the expansion and contraction of the boom cylinder 6. The base end of the arm 3 is rotatably connected to the tip of the boom 2 about a horizontal axis, and the arm 3 rotates with respect to the boom 2 as the arm cylinder 7 extends and contracts. The bucket 1 is attached to the tip of the arm 3 via a shaft 9 and is connected to the bucket cylinder 5 via a link 4 and a shaft 10. Rotate around.

In this hydraulic excavator, in addition to the three hydraulic actuators of the cylinders 5, 6 and 7, a swing hydraulic motor (hydraulic actuator) 12 as shown in FIG.
Left and right traveling hydraulic motors (hydraulic actuators) 14, 16
Are provided, and further, six operation levers (operation command means) 21 to 26 are provided corresponding to the respective hydraulic actuators. Specifically, the operating lever 21 is for operating the boom cylinder 6, and the operating lever 22 is for operating the arm cylinder 7.
The operating lever 23 is for operating the bucket cylinder 5, the operating lever 24 is for operating the swing hydraulic motor 12, the operating lever 25 is for operating the left traveling hydraulic motor 14, and the operating lever 26 is for operating the above. Each of the right traveling hydraulic motors 16 is provided for driving operation, and is configured to output an operation command signal according to the operation amount of the lever.

On the other hand, as a drive control system for each of the hydraulic actuators, a hydraulic circuit 28, a controller 30, and a hydraulic pump 40 as shown in FIG. 2 are provided, and operation commands from the operation levers 21 to 26 are provided. A signal is input to the hydraulic circuit 28 and the controller 30.

The hydraulic circuit 28 is provided between the hydraulic pump 40 and each hydraulic actuator, and the hydraulic pump 40
The operating oil discharged from the operation levers 21 to 26
The flow rate is made to flow to each hydraulic actuator according to the operation amount of. The hydraulic pump 40 is composed of an axial piston pump in this embodiment, and the discharge amount can be adjusted by changing the tilt angle α thereof.

In the present invention, the hydraulic pump is not limited to a specific structure, and various types can be used as long as the discharge amount is variable. For example, an unbalanced vane pump may be used to change the amount of eccentricity.

The controller 30 includes the operation levers 21 to 21.
The discharge amount of the hydraulic pump 40 is controlled on the basis of the manipulated variable of 26, and includes individual discharge amount calculating means 31 to 36 and total discharge amount calculating means 38 as shown in FIG.

The individual discharge amount calculation means 31 to 36 receive the operation command signals from the operation levers 21 to 26, respectively, and the required pump discharge amount (individual discharge amount) q ₁ to for each hydraulic actuator corresponding to the operation amount. This is to find q ₆ .
Specifically, the individual discharge amount calculation means 31 to 36 are data tables as shown in FIGS. 3A to 3C and 4A to 4C, that is, the lever operation amounts s _{1 to} s _6. pump discharge quantity q ₁ previously stores data tables about the characteristics of to q _6, is configured to read the individual discharge amount for the hydraulic actuators from the data table for.

Incidentally, FIGS. 3 (a) to 3 (c) and FIG. 4 (a)
In (c), q _min is the minimum required discharge amount when the hydraulic actuator is stopped, that is, must be flown in the stopped state in order to smoothly shift the hydraulic actuator from the stopped state to the operating state. Indicates the required flow rate.

The total discharge amount calculation means 38 is operated by the individual discharge amount calculation means 31 to 36 to read the individual discharge amounts q ₁ to q.
Based on q ₆ , the final required pump discharge amount (total discharge amount) Q by the hydraulic pump 40 is calculated, and a control signal is output to the pump control solenoid proportional valve 42 so as to obtain this total discharge amount Q. To do. Specifically, the total discharge amount calculation means 38 is configured to calculate the total discharge amount Q based on the following (Equation 3).

[0024]

[Equation 3]

The pump control solenoid proportional valve (discharging amount control means) 42 adjusts the tilt angle α of the hydraulic pump 40 so as to correspond to the total discharging amount Q.

Next, the operation of this device will be described.

First, when all the operating levers 21 to 26 are not operated, the individual discharge amount calculating means 31 to 3
6, the lever operation amounts s _{1 to} s ₆ are all taken as 0, and the individual discharge amounts q _{1 to} q ₆ read by the individual discharge amount calculating means 31 to 36 are all q _min . Therefore, the total discharge amount Q calculated by the total discharge amount calculating means 38 in the above (Equation 3) is q _min , and the tilt angle α of the hydraulic pump 40 is adjusted so as to obtain this discharge amount. Due to the action of the hydraulic circuit 30, the hydraulic oil from the hydraulic pump 40 is allowed to escape to the tank as it is without flowing to each hydraulic actuator.

On the other hand, when at least one operation lever is operated, the operation amount is fetched by the individual discharge amount calculation means and the individual discharge amount corresponding to the operation amount is calculated. Therefore, the total discharge amount calculation means 38 calculates a total discharge amount Q larger than the required minimum discharge amount q _min, and the hydraulic actuator corresponding to the operated operation lever has an amount corresponding to the operated amount. Hydraulic fluid is drained.

For example, when the operation levers 21 and 22 are operated, the individual discharge amounts q ₁ and q ₂ corresponding to the operation amounts s ₁ and s ₂ are displayed in the tables of FIGS. 3 (a) and 3 (b). Based on the individual discharge amount calculation means 31 and 32,
In the total discharge amount calculation means 38, the minimum discharge amount q _min
The amount added by {(q ₁ −q _min ) + (q ₂ −q _min )} is calculated as the total discharge amount Q. Therefore, hydraulic oil is introduced into the hydraulic actuators (that is, the boom cylinder 6 and the arm cylinder 7) corresponding to the operation levers 21 and 22 at a flow rate sufficient to meet the operation amounts s _{1 to} s ₂ , and both cylinders 6 , 7 operate at a speed suitable for the operation levers 21 and 22.

This series of operations is shown in the flowchart of FIG.

As described above, in this device, the individual discharge amounts q _{1 to} q ₆ corresponding to the lever operation amounts s _{1 to} s ₆ of the respective operation levers 21 to 26 are obtained by the individual discharge amount calculation means 31 to 36,
Since the total discharge amount Q, which is the actual pump discharge amount, is calculated based on the sum of these individual discharge amounts q _{1 to} q ₆ , when a plurality of hydraulic actuators are driven by a single hydraulic pump 40. Also, each hydraulic actuator can be operated at a sufficient speed corresponding to the above operation amount without causing a shortage of the pump discharge amount. Moreover, unlike the conventional device that performs feedback control, the pump discharge amount (total discharge amount) is always adapted to the operation levers 21 to 26 without being influenced by external factors such as a load acting on the hydraulic actuator. Q can be set.

Further, in the apparatus of this embodiment, in calculating the total discharge amount Q, each individual discharge amount q _{1 to} q ₆ is not simply added, but each individual discharge amount is calculated as shown in (Equation 3). Amount obtained by subtracting the minimum required discharge amount q _min from the discharge amounts q _{1 to} q ₆ (that is, the amount added to the minimum required discharge amount q _min )
Since the minimum required discharge amount q _min is added to this, the minimum required discharge amount q _min is secured while all the operation levers 21 to 26 are not operated (stopped state). When at least one operation lever is operated, the minimum discharge amount required to accurately operate the hydraulic actuator corresponding to the operation lever can be set as the total discharge amount, and the hydraulic pump 30 is not used. It is possible to prevent the discharge of a large amount.

The present invention is not limited to such an embodiment, and the following modes can be adopted as an example.

(1) In the present invention, regardless of the type of hydraulic actuator, the present invention can be applied to the driving of various hydraulic actuators that operate by the supply of hydraulic oil in addition to the cylinders and motors. Further, the present invention can be widely applied to a system in which a plurality of hydraulic actuators are driven by a common hydraulic pump, regardless of the specific number of hydraulic actuators.

(2) In the above embodiment, the operating levers 21 to 2
Although the flow rate of the hydraulic oil to each hydraulic actuator and the pump discharge amount are controlled according to the operation amount of No. 6, the operation command means in the present invention is not limited to the operation lever as described above, but operates the hydraulic actuator. The present invention can be widely applied as long as it outputs a command signal for For example, in a machine in which the drive of each cylinder is automatically controlled so that the bucket draws a desired excavation trajectory set in advance, instead of the operation by the manual operation as described above, the control device controls each hydraulic actuator to The individual discharge amount and the total discharge amount may be calculated based on the output operation command signal.

(3) In the present invention, the relationship between the content of the operation command signal (lever operation amount s _{1 to} s _{6 in the} above embodiment) and the individual discharge amount is shown in FIGS. 3 (a) to 3 (c) and FIG. (A) ~
The setting is not limited to that shown in (c), and may be set freely according to the characteristics of the hydraulic machine.

[0037]

As described above, according to the present invention, the individual discharge amount corresponding to the operation command signal for each hydraulic actuator is obtained, and the total discharge amount, which is the actual pump discharge amount, is set based on the sum of these individual discharge amounts. As described above, even when a plurality of hydraulic actuators are driven by a single hydraulic pump, the pump discharge amount is not insufficient and each hydraulic actuator is driven at a sufficient speed corresponding to the operation amount. There is an effect that can be activated. Moreover,
Unlike a conventional feedback control device, the pump discharge amount (total discharge amount) Q is always set in accordance with the operation command signal without being influenced by external factors such as a load acting on the hydraulic actuator. be able to.

Further, in the apparatus according to the second aspect, when the total discharge amount Q is calculated, each individual discharge amount is not simply added but the minimum required discharge amount q is calculated from each individual discharge amount.
_Since the sum of the amount obtained by subtracting _min (that is, the amount added to the minimum required discharge amount q _min ) is taken and the minimum required discharge amount q _min is added to this, all hydraulic actuators are stopped. While the minimum required discharge amount q _min is secured, while at least one hydraulic actuator is operating, the minimum discharge amount required to operate this hydraulic actuator accurately can be set as the total discharge amount, There is an effect that it is possible to prevent an unnecessary amount of discharge from the hydraulic pump.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of a controller according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a drive control system of a hydraulic actuator including the controller.

3A, 3B, and 3C are graphs showing the relationship between the lever operation amount and the pump discharge amount for each cylinder of the hydraulic actuator.

4A, 4B, and 4C are graphs showing the relationship between the lever operation amount and the pump discharge amount for each motor of the hydraulic actuators.

FIG. 5 is a flowchart showing a control operation performed by the controller.

FIG. 6 is a side view of a hydraulic excavator equipped with the device of the present invention.

FIG. 7 is a hydraulic circuit diagram showing an example of a conventional pump discharge amount control device.

FIG. 8 is a graph showing a characteristic of a pump discharge amount with respect to a detected pressure in the above apparatus.

[Explanation of symbols]

 5 Bucket Cylinder (Hydraulic Actuator) 6 Boom Cylinder (Hydraulic Actuator) 7 Arm Cylinder (Hydraulic Actuator) 12 Swing Hydraulic Motor (Hydraulic Actuator) 14 Left Running Hydraulic Motor (Hydraulic Actuator) 16 Right Running Hydraulic Motor (Hydraulic Actuator) 21-26 Operation lever (operation command means) 28 Hydraulic circuit 30 Controller 31-36 Individual discharge amount calculation means 38 General discharge amount calculation means 40 Hydraulic pump

Claims (2)

[Claims] 1. A device for controlling the discharge rate of a variable displacement hydraulic pump that drives a plurality of hydraulic actuators in common, and an operation command means for outputting an operation command signal for each hydraulic actuator, and the operation command means. Of the required hydraulic pump based on the sum of the individual discharge amount calculation means for obtaining the required pump discharge amount for each hydraulic actuator corresponding to the operation command signal of A hydraulic pump comprising: a total discharge amount calculation means for calculating a discharge amount; and a discharge amount control means for controlling an actual discharge amount of the hydraulic pump based on a calculation result of the total discharge amount calculation means. Discharge rate control device. 2. The hydraulic pump discharge amount control device according to claim 1, wherein the number of hydraulic actuators is N, the minimum required pump discharge amount when all hydraulic actuators are stopped is q _min , and the individual discharge amount is for the i-th hydraulic actuator. A discharge amount control device for a hydraulic pump, characterized in that the total discharge amount calculation device is configured to calculate a total discharge amount Q based on the following equation, where qi is a required discharge amount obtained by the calculation device. .. [Equation 1]