JP3479451B2 - Control method and control device for hydraulic pump - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pump control method and control device applied to a power unit system including an engine and a hydraulic pump mounted on a construction machine such as a hydraulic excavator. .

[0002]

2. Description of the Related Art Generally, a hydraulic excavator of this type includes first and second variable displacement hydraulic pumps driven by engine power, and discharges pressure oil from the first and second hydraulic pumps. It is configured to supply to a plurality of hydraulic actuators via a control valve whose opening amount changes according to the lever operation amount.

In FIG. 11, reference numeral 1 denotes a hydraulic excavator as a construction machine. The hydraulic excavator 1 has a swing motor (not shown) for swinging an upper swing body 2 and a boom 3.
There are provided hydraulic actuators such as a boom cylinder 4 for operating the, a stick cylinder 6 for operating the stick 5, and a bucket cylinder 8 for operating the bucket 7.

In order to supply pressure oil to these plural hydraulic actuators that are operated in a complex manner without excess or deficiency, the pump absorption horsepower (or absorption torque) is adjusted so that the actual rotation speed follows the target rotation speed of the engine. It is required to control engine horsepower (or engine torque) in good balance.

FIG. 12 is a block diagram of a conventional power unit system. In FIG. 12, 9,
Reference numeral 10 denotes first and second variable displacement hydraulic pumps that are driven by the power of the engine 11 to supply pressure oil to the plurality of hydraulic actuators. These first and second hydraulic pumps 9, Reference numeral 10 is a swash plate type axial piston pump in which the pump discharge flow rate changes based on the swash plate angular displacement of the swash plates 9a and 10a.

The swash plates 9a and 10a are displaced by respective pump regulators 12 and 13. These pump regulators 12 and 13 control the pressure Ps output from the electromagnetic proportional pressure reducing valve 14, the pressure of the circuit through which the pressure oil passing through the control valve flows to the tank, and the circuit pressure of the discharge portion of the hydraulic pumps 9 and 10. Controlled by.

In the discharge circuits of the hydraulic pumps 9 and 10, pilot-operated control valves 15 and 17 for switching the flow rate and direction of pressure oil to the hydraulic actuator are provided, and these control valves 15 and 17 are passed through. Relief valves 16 and 18 for setting the operating hydraulic pressures supplied from the hydraulic pumps 9 and 10 are provided in the hydraulic circuits in which the pressure oil flows into the tanks, respectively.

At the pilot operating parts of the control valves 15 and 17, a pressure reducing valve (hereinafter,
This pressure reducing valve is referred to as a "remote control valve" 19 and 20, and pilot operation pressure corresponding to the lever operation amount of these remote control valves 19 and 20 is transmitted to the control valves 15 and 17.

When the lever operation amount of the remote control valves 19 and 20 is zero, the pressure oil discharged from the hydraulic pumps 9 and 10 flows into the tank 26 via the control valves 15 and 17 and the relief valves 16 and 18. . At this time, the inlet pressure of the relief valves 16 and 18 becomes the relief set pressure. On the other hand, the remote control valve 19,
When the lever 20 is operated, the pressure oil that has passed through the control valves 15 and 17 is supplied to the hydraulic actuator, and the relief valve 1
Since there is no pressure oil passing through 6 and 18, relief valves 16 and 1
The inlet pressure of 8 drops to near the tank pressure. That is,
The inlet pressure of the relief valves 16 and 18 changes depending on the lever operation amount, and the pressure is transmitted to the pump regulators 12 and 13.

In FIG. 12, a controller 30 for inputting a detection signal from a sensor and outputting a command signal to the electromagnetic proportional pressure reducing valve 14 is provided. This controller
The sensor signal to 30 is a rotation speed sensor 22 that detects the actual rotation speed of the engine 11 and a pressure switch 31 that determines whether or not the hydraulic pumps 9 and 10 are discharging pressure oil. Is a control pressure P to the pump regulators 12 and 13 in order to control the absorption horsepower (or torque) of the hydraulic pump so that the actual engine speed follows the target speed.
Outputs the command signal (electrical signal) that becomes s.

The command signal of the control pressure Ps is converted into oil pressure by the electromagnetic proportional pressure reducing valve 14 and becomes a hydraulic pressure for controlling the pump regulators 12, 13, that is, the control pressure Ps. The control pressure Ps operates the pump regulators 12, 13. To do.

[0012]

According to this conventional horsepower (torque) control method, the operation amount of the control valves 15, 17 by the remote control valves 19, 20 or a signal corresponding to the operation amount is not input to the controller 30.

Therefore, the balance between the engine output and the pump absorption torque immediately after the lever operation or at the time of the fine operation is lost, and the fluctuation of the actual rotation speed with respect to the engine target rotation speed becomes large.

Further, when the model of the hydraulic excavator is different, the controller 30 needs to be tuned each time the model of the hydraulic excavator is different. In short, a part of the control program needs to be modified for each model.

Further, there are individual differences in hydraulic excavators even if they are of the same model. In addition, the working environment may be different, such as in cold regions or warm regions, or the fuel used for the engine may be changed.

If the individual differences, working environment and conditions are different as described above, the tuning performed before shipping the hydraulic excavator cannot be applied, and the fluctuation of the actual rotation speed with respect to the engine target rotation speed becomes large, impairing the operability. I will end up.

The present invention has been made in view of the above points, and can be flexibly adapted to individual differences of construction machines and different working environments, and the same control program can be applied to different types of construction machines. An object of the present invention is to provide a control method and a control device for a hydraulic pump that can be used.

[0018]

According to the invention described in claim 1, an engine speed, a pump discharge pressure of pressure oil discharged from a variable displacement hydraulic pump driven by the engine, and a hydraulic pump. The flow rate change of the hydraulic pump during operation is predicted from the signal corresponding to the operation amount of the control valve that controls the direction and flow rate of the pressure oil supplied to the actuator, and the hydraulic pump is predicted from the predicted flow rate change of the hydraulic pump. Is a control method for the hydraulic pump, in which the control output torque is calculated and the hydraulic pump is controlled based on the control output torque.

This makes it possible to accurately predict the flow rate of the hydraulic pump during operation from the engine speed, the pump discharge pressure, and the signal corresponding to the operation amount of the control valve. The actual engine speed is made to follow the engine target engine speed or the actual engine speed is settled stably near the engine target engine speed so that the balance with the pump absorption torque is not lost.

According to a second aspect of the present invention, in the control method for the hydraulic pump according to the first aspect, the compatibility of the pressure oil discharged from the plurality of hydraulic pumps with respect to each range of the pump discharge pressure and the total predicted flow rate is shown. , The control output torque of the hydraulic pump is calculated by the product of the rotational speed error of the actual engine rotational speed and the reference rotational speed corresponding to the engine target rotational speed,
A method for controlling a hydraulic pump, which operates a control output torque of the hydraulic pump according to an output state of the hydraulic pump during operation and an error in the number of revolutions of the engine.

Thus, the control output torque of the hydraulic pump can be manipulated according to the output state of the pump during operation and the error in the engine speed, and the output state of the pump changes depending on the model of the construction machine, individual differences, etc. Even if the dynamic characteristics of the engine speed change due to engine characteristics due to environmental changes (for example, cold regions, warm regions, etc.) or engine fuel changes,
The learning calculation enables control of the hydraulic pump according to each construction machine. Further, by the learning calculation, the same control program can be used even if the model of the construction machine is different, and the work of changing the control program for each model is eliminated.

According to a third aspect of the present invention, in the hydraulic pump control method according to the first aspect, the rotational speed error of the actual engine rotational speed with respect to the engine target rotational speed and the rotational speed change of the actual engine rotational speed over time. The control output torque of the hydraulic pump is calculated from the product of the goodness of fit for each range of the quantity and the conversion error calculated from the rotation speed error and the rotation speed change amount, the characteristics of the hydraulic pump during operation, the engine speed A method for controlling a hydraulic pump, which operates a control output torque of the hydraulic pump according to an error and a rotational speed change amount.

Thus, the control output torque of the hydraulic pump can be manipulated according to the characteristics of the pump during operation, and also according to the error in the engine speed and the amount of change in the engine speed per unit time. In other words, the output characteristics of the pump change due to the type of construction equipment, individual differences, etc., and the dynamic characteristics of the engine speed change with the engine characteristics due to changes in the work environment (eg cold regions, warm regions, etc.) and engine fuel changes. Even if it does, it becomes possible to control the hydraulic pump according to each construction machine by the learning calculation. Further, by the learning calculation, even if the model of the construction machine is different, the same control program can be used, and the work of changing the control program for each model is eliminated.

According to a fourth aspect of the present invention, an engine, a plurality of variable displacement hydraulic pumps driven by the engine, and a plurality of units for controlling the direction and flow rate of the pressure oil discharged from these hydraulic pumps. Control valve of
A plurality of relief valves that set the pressure of the pressure oil supplied to the actuator via these control valves, the engine speed, the pump discharge pressure of the pressure oil discharged from the hydraulic pump, and the relief pressure at the inlet of the relief valve. From, the flow rate change of the hydraulic pump during operation is predicted, the controller that calculates and outputs the control output torque of the hydraulic pump, the electro-hydraulic conversion valve that converts the output signal of this controller into the control pressure, the control pressure, A control device for a hydraulic pump, comprising a pump regulator for controlling a discharge flow rate adjusting means of the hydraulic pump according to a relief pressure and a pump discharge pressure.

As a result, the engine speed, pump discharge pressure, and the operation amount of the control valve or a signal corresponding to the operation amount are input to the controller, and the controller predicts the flow rate of the hydraulic pump during operation, The control output torque of the pump is calculated, the output signal of the controller is output to the electro-hydraulic conversion valve, and the control pressure output from the electro-oil conversion valve,
By controlling the discharge flow rate adjusting means of the hydraulic pump with the pump regulator based on the relief pressure and the pump discharge pressure, it is possible to accurately predict the flow rate of the hydraulic pump during operation. The actual engine speed can be made to follow the engine target engine speed without losing the balance with the absorption torque.

[0026]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to FIGS.
Will be described with reference to the embodiment shown in FIG. Since the hydraulic excavator shown in FIG. 11 has already been described, the description thereof is omitted and the same parts as those of the conventional power unit system shown in FIG. 12 are designated by the same reference numerals.

First, FIGS. 1 to 7 show an embodiment according to the present invention, and in particular, FIGS. 5 to 7 show a first embodiment in the case of executing fuzzy inference by a controller of a power unit system. .

FIG. 1 is a block diagram showing the configuration of the power unit system of the present invention. In FIG. 1, 9,
Reference numeral 10 denotes first and second variable displacement hydraulic pumps that are driven by the power of the engine 11 to supply pressure oil to the plurality of hydraulic actuators. The hydraulic pump 10 has swash plates 9a, 10a as the discharge flow rate adjusting means.
It is composed of a swash plate type axial piston pump in which the discharge flow rate of each pump changes by variably controlling the tilt angles of a and 10a.

The swash plates 9a and 10a are displaced by respective pump regulators 12 and 13. These pump regulators 12 and 13 are the control pressure Ps output from the electromagnetic proportional pressure reducing valve 14 as an electro-oil conversion valve, the pressure of the circuit in which the pressure oil passing through the control valves 15 and 17 flows to the tank, and the hydraulic pump. It is controlled by the circuit pressures of the discharge units 9 and 10.

Pilot-operated control valves 15 and 17 for controlling the flow rate and direction of pressure oil to the hydraulic actuator are provided in the discharge circuits of the hydraulic pumps 9 and 10 and pass through these control valves 15 and 17. Relief valves 16 and 18 for setting operating hydraulic pressures supplied from the hydraulic pumps 9 and 10 are provided in the hydraulic circuits through which the pressure oil that flows into the tanks, respectively.

At the pilot operating parts of the control valves 15 and 17, a pressure reducing valve (hereinafter,
This pressure reducing valve is referred to as a "remote control valve" 19 and 20 are connected by a pilot line, and the pilot operation pressure corresponding to the lever operation amount of these remote control valves 19 and 20 is transmitted to the control valves 15 and 17, and the control valve Each spool of 15 and 17 is displaced.

When the operation amount of the control valves 15 and 17 by the lever-operated remote control valves 19 and 20 is zero, the pressure oil discharged from the hydraulic pumps 9 and 10 is the control valve 1.
It flows into the tank 26 through 5, 17 and the relief valves 16, 18. At this time, the inlet pressure of the relief valves 16 and 18 becomes the relief set pressure.

On the other hand, when the remote control valves 19 and 20 are operated by levers, the spools of the control valves 15 and 17 are displaced by the pilot pressure from the remote control valves 19 and 20, and the hydraulic pumps 9 and 10 are displaced.
The pressure oil discharged from the valve passes through the control valves 15 and 17 and is supplied to the hydraulic actuator. The pressure oil that passes through the relief valves 16 and 18 disappears, so the inlet pressure of the relief valves 16 and 18 drops to near the tank pressure. To do.

That is, the inlet pressure of the relief valves 16 and 18 changes depending on the lever operation amount of the remote control valves 19 and 20, and the relief pressure P at the inlets of these relief valves 16 and 18 is changed.
r1 and Pr2 are transmitted to the pump regulators 12 and 13.

In FIG. 1, reference numeral 21 is a controller. The controller 21 has a detection signal from a rotation speed sensor 22 for detecting an actual engine rotation speed Ne and hydraulic pumps 9 and 10.
The detection signals of the pressure sensor 23 for detecting the pump discharge pressure Pp discharged from the pump and the detection signals of the pressure sensors 24, 25 for detecting the relief pressures Pr1, Pr2 at the inlets of the relief valves 16, 18 are respectively inputted, and this controller is inputted. 21 outputs a command signal input to the electromagnetic proportional pressure reducing valve 14.

As shown in FIG. 5, the controller 21 controls the relief pressure Pr1 of the pressure oil passing through one control valve 15, the pump discharge pressure Pp, and the pressure of the previous step output from the controller 21 to the electromagnetic proportional pressure reducing valve 14. Discharge flow rate Q1 of the first hydraulic pump 9 from the command signal of the control pressure Ps
And a relief pump Pr2 for the pressure oil passing through the other control valve 17,
A second pump discharge oil amount prediction calculation unit 51 that predicts the discharge flow rate Q2 of the second hydraulic pump 10 from the command signals of the pump discharge pressure Pp and the control pressure Ps of the previous step, and both of the obtained predicted discharge flow rates Q1 and A total flow rate predicting calculation unit 52 for calculating the total predicted flow rate Q from Q2, and an antecedent unit calculation unit 53 for calculating a combined value μij of the degree of conformity to the antecedent part of the fuzzy rule from the pump discharge pressure Pp and the total predicted flow rate Q. The reference engine speed calculation unit 54 for calculating the engine reference engine speed Nr so that the actual engine speed Ne can smoothly follow the target value change even when the engine target engine speed Nset changes stepwise.
And a subtractor 55 for calculating the rotation speed error ΔNe of the actual engine rotation speed Ne with respect to the engine reference rotation speed Nr, and the rotation speed error ΔNe and the antecedent composite value μij output from the antecedent calculation unit 53 for fuzzy Control for calculating the control output torque Tr of the hydraulic pumps 9 and 10 using the consequent part calculator 56 that calculates the value of the consequent part variable Wij of the rule, and the combined value μij of the consequent part variable Wij and the antecedent part. An output torque calculation unit 57 and a control pressure converter 58 for converting the control output torque Tr into a command signal of the control pressure Ps for the electromagnetic proportional pressure reducing valve 14 are provided. The antecedent part computing part 53 and the consequent part computing part 56 are fuzzy inference computing parts. The function of each unit will be described later.

Next, the operation of the first embodiment will be described.

(1) Engine output characteristic FIGS. 2 and 3 show the relationship between the engine output characteristic and the target rotation speed. When FIG. 2 uses 100% of the engine output, FIG. 3 changes the accelerator dial. However, the engine output is 100% or less.

The engine output is divided into a governor region and a lagging region with the point of the rated torque Te as a boundary. The governor region is an output region when the governor opening is 100% or less, and the lagging region is an output region when the governor opening is 100%.

When the hydraulic excavator performs heavy excavation work, the engine output is set to 100% and the work is performed in a good fuel economy state. Therefore, the point indicated by the ● mark in FIG. 2, that is, the rated speed (engine at the rated point The engine target speed Nset is set to a position slightly lower than the (speed).

When the hydraulic excavator does light work, the engine output may be 100% or less, and the accelerator dial may be lowered, so that the abscissa value of the point indicated by ● in FIG. 3 is the target rotation. Becomes a number. Also, the ordinate value of the above-mentioned ● becomes the target engine output torque.

The controller 21 operates the pump regulators 12 and 13 of the hydraulic pumps 9 and 10 so that the absorption torques of the hydraulic pumps 9 and 10 are balanced with the engine output.

(2) Hydraulic Pump Regulator Characteristics FIG. 4 shows the characteristics of the pump regulators 12 and 13 that control the swash plates 9a and 10a of the hydraulic pumps 9 and 10.

In FIG. 4, the maximum discharge flow rate Qu when the pump discharge pressure Pp discharged from the hydraulic pumps 9 and 10 is low is the relief pressure Pr1 or the relief pressure that changes depending on the lever operation amount of the remote control valve 19 or the remote control valve 20. Increase or decrease with pressure Pr2. For example, when the lever operation amount of the remote control valves 19 and 20 is small, the pump regulators 12 and 13 operate so that the maximum discharge flow rate Qu becomes low.

When the pump discharge pressure Pp of the hydraulic pumps 9 and 10 is medium and high pressure, the discharge flow rate QL decreases as the pump discharge pressure Pp increases. This pressure range (the region of the diagonal characteristic line in FIG. 4) is the region where the absorption torque or horsepower of the hydraulic pump becomes constant (called constant torque curve or constant horsepower curve), and When the control pressure Ps output from the electromagnetic proportional pressure reducing valve 14 to the pump regulators 12 and 13 is changed by the commanded electric signal, the above curve is shifted and the pump absorption torque or horsepower is changed.

Further, if the expression is changed, the relief pressure Pr1
Alternatively, the discharge flow rate Qu of the hydraulic pump 9 or the hydraulic pump 10 can be estimated by the relief pressure Pr2, and the discharge flow rate QL on the constant torque curve can be estimated by the command signal of the current control pressure Ps and the pump discharge pressure Pp. It will be possible. That is, it becomes possible to estimate the pump discharge flow rate during operation.

(3) Hydraulic Pump Control Method FIG. 5 is a block diagram showing a first embodiment of the pump control calculation function in the power unit system controller according to the present invention. In FIG. 5, the first pump discharge oil is shown. The amount prediction calculation unit 50 uses the pump regulator characteristic of FIG. 4 described above to calculate the relief pressure Pr1 and the pump discharge pressure Pp.
Also, the pump discharge flow rate Q1 of the first hydraulic pump 9 is predicted from the command signal of the control pressure Ps in the previous step. The second pump discharge oil amount prediction calculation unit 51 also predicts the pump discharge flow rate Q2 of the second hydraulic pump 10 using the pump regulator characteristic of FIG.

The total flow rate prediction calculation unit 52 calculates the total predicted flow rate Q from the obtained predicted discharge flow rates Q1 and Q2.

Q = Q1 + Q2 (1) The pump discharge pressure Pp and the total predicted flow rate Q are input to the antecedent part calculation part 53 to calculate the suitability of the fuzzy rule to the antecedent part (if-part).

FIG. 6 shows a fuzzy rule. In this table, for pump discharge pressure Pp, NB, NM,
NS, ZO, PS, PM, PB are described, and NB, NM, NS, ZO, PS,
The part described as PM and PB corresponds to the rule of the antecedent part. Wij (i = 1 to 7, j = 1 to 7) in the table is the consequent part variable.

NB is Negative Big, NM is Negative Medi
um, NS is Negative Small, ZO is Zero, PS is Positi
veSmall, PM is Positive Medium, PB is Positive Big
Is an abbreviation for and is called a fuzzy label.

With respect to the pump discharge pressure Pp, NB means that the pressure is considerably small, PB means that the pressure is considerably large, and for the total predicted flow rate Q, NB has a considerably small flow rate and PB has a small flow rate. It means that it is quite large.

The goodness of fit quantitatively represents the goodness of fit to each fuzzy label. In the case of fuzzy control,
The membership function is used for the above quantification.

FIG. 7 shows an example of the membership function, which relates to the pump discharge pressure Pp. For example, in the case of the antecedent rule if Pp is NM, the membership function (triangle) corresponding to NM in FIG. 7 is used to obtain the value of the membership function with respect to the pump discharge pressure Pp, and the above value is set to the above value. It is defined as the degree of conformity to the antecedent rule. The same applies to other antecedent rules.

Next, the antecedent part computing part 53 obtains a composite value of the respective antecedent part conformances as follows.

The degree of conformity of the antecedent rule with respect to the pump discharge pressure Pp is μj, j = 1 to 7 (j = 1 is NB, j
= 2 corresponds to NM, ..., j = 7 corresponds to PB), and the respective suitability of the antecedent rule to the total predicted flow rate Q is μi, i
= 1 to 7 (i = 1 is NB, i = 2 is NM, ..., i =
7 corresponds to PB), and the combined value μij of μi and μj
Is calculated by the following formula.

Μij = μi × μj (2) In addition to the method described above, there is also a method of using the following formula as the method of calculating the composite value.

[0058]   μij = min (μi, μj) (3) Where min is a function that selects the minimum value.

The reference engine speed calculating section 54 sets an engine target engine speed N set by an accelerator dial (not shown).
Even if the set changes stepwise, the engine reference speed Nr is calculated so that the actual engine speed Ne can smoothly follow the target value change. Engine reference speed N
r is calculated, for example, by applying “(dead time) + (first-order delay)” to the engine target speed Nset.

In the subtractor 55, the rotation speed sensor for the engine reference rotation speed Nr calculated by the reference rotation speed calculation unit 54 is used.
The error ΔNe of the actual engine speed Ne detected at 22 is calculated.

The consequent calculation unit 56 informs the rotation speed error ΔNe of the actual engine rotation speed Ne with respect to the engine reference rotation speed Nr.
And the composite value μij output from the antecedent part computing part 53 are input, and the value of the consequent part variable Wij is calculated by the following equation.

Wij (k) = Wij (k-1) −γ · Δt · ΔNe · μij (4) where (k) and (k-1) represent steps in control, and (k)
Represents the current step and (k-1) represents the previous step. Further, γ is a learning gain, Δt is a control step time, ΔN
e is the rotation speed error, μij is the combined fitness value of the antecedent,
i = 1 to 7 and j = 1 to 7.

Using the equation (4), the conformance of the antecedent rule is high (the antecedent rule that matches more), and the rotation speed error Δ
The larger Ne is, the larger the second term of the equation (4) becomes, and the larger the correction amount for the consequent part variable Wij (k-1) in the previous step becomes. Further, since the second term changes until the rotation speed error ΔNe disappears, the consequent part variable Wij is corrected (learned).

The transition of the pump discharge pressure Pp and the total predicted flow rate Q depends on the lever operation amount of the remote control valves 19 and 20, the individual difference between the engine and the pump, and the characteristic changes such as the model. With a comprehensive membership function, it is possible to realize pump control capable of coping with the characteristic changes.

That is, the antecedent part rule most suited to the characteristic change becomes the object of the calculation, and the antecedent part variable Wij corresponding to the antecedent part rule of the above object is updated so that the rotational speed error ΔNe becomes zero. It will be (to learn).

The control output torque calculation unit 57 calculates the control output torque Tr of the hydraulic pump by the following equation using the consequent part variable Wij (k) and the antecedent part composite value μij.

Tr = Σ (μij × Wij (k)) / Σμij (5) The formula (5) is a so-called weighted average calculation formula and is a general formula for obtaining the output value of the fuzzy control.

The control output torque Tr is converted by the control pressure converter 58 into a command signal of the control pressure Ps for the electromagnetic proportional pressure reducing valve 14.

When the accelerator dial is changed, the engine target speed Nset is also changed. Therefore, in the present invention,
A consequent variable Wij is prepared for each accelerator dial, and learning calculation is performed for each accelerator dial. By doing so, appropriate control (learning) is performed for each accelerator dial.

(4) Effects of the First Embodiment As described specifically above, according to the first embodiment,
The actual engine speed Ne, the pump discharge pressure Pp, and the relief pressures Pr1 and Pr2, which are signals corresponding to the operation amounts of the remote control valves 19 and 20 by the operation levers or the operation amounts, are input to the controller 21, respectively. , It is possible to accurately predict the flow rate of the hydraulic pumps 9 and 10 during operation,
The actual engine speed Ne can be made to follow the engine target speed Nset without losing the balance between the engine output and the pump absorption torque immediately after the lever operation or during the fine operation.

Further, each conformity for each range of the pump discharge pressure Pp and the total predicted flow rate Q, and the rotation speed error Δ of the actual engine rotation speed Ne with respect to the engine reference rotation speed Nr.
Based on the product with Ne, the control output torque Tr of the pump is learned.
Therefore, the control output torque of the hydraulic pumps 9 and 10 can be manipulated according to the output state of the hydraulic pumps 9 and 10 in operation and the rotation speed error ΔNe of the engine 11.

That is, the output state of the hydraulic pumps 9 and 10 changes depending on the model of the hydraulic excavator and individual differences, the working environment changes (for example, cold regions, warm regions), and the engine characteristics due to the engine fuel changes. Even if the dynamic characteristics of the rotation speed change, the control side learns and the hydraulic pump can be controlled according to each hydraulic excavator.

Further, by the learning calculation, even if the model of the hydraulic excavator is different, the same control device (control method) can be used, and the work of changing the control program for each model is eliminated.

Next, FIGS. 8 to 10 show a second embodiment in which fuzzy inference is executed by a power unit system controller according to the present invention. 1 to 4
Since the configuration of the power unit system shown in (1) is basically used in this second embodiment as well, refer to FIGS. 1 to 4 as necessary.

The second embodiment is largely different from the first embodiment in the configuration of the hydraulic pump control calculation unit of the controller 21 and the hydraulic pump control method.

As shown in the pump control calculation block diagram of FIG. 8, the controller 21 has a relief pressure Pr1 of pressure oil passing through one control valve 15, a pump discharge pressure Pp, and an electromagnetic proportional pressure reducing valve from the controller 21. The first pump discharge oil amount prediction calculation unit 60 that predicts the discharge flow rate Q1 of the first hydraulic pump 9 from the command signal of the control pressure Ps of the previous step output to 14, and the pressure oil that passes through the other control valve 17 A second pump discharge oil amount prediction calculation unit 61 that predicts the discharge flow rate Q2 of the second hydraulic pump 10 from the command signals of the relief pressure Pr2, the pump discharge pressure Pp, and the control pressure Ps of the previous step, and the obtained predicted discharge flow rate. A total flow rate predicting / calculating section 62 for calculating a total predicted flow rate Q from Q1 and Q2, a rotation speed error ΔNe of an actual engine speed Ne with respect to an engine target speed Nset, and an actual engine speed A rotational speed error / rotational speed change amount calculation unit 64 for calculating the rotational speed change amount DNe of the number Ne, and a combination of the adaptability to the antecedent part of the fuzzy rule from the rotational speed error ΔNe and the rotational speed change amount DNe. The antecedent calculation unit 63 for calculating the value μij and the rotation speed error Δ
A conversion error calculator 65 that calculates a conversion error Δf from Ne, a rotation speed change amount DNe, a total predicted flow rate Q and a pump discharge pressure Pp, and a consequent part variable of a fuzzy rule from the conversion error Δf and a combined value μij of the antecedent parts. Consequent part calculation part to calculate Wij
66, a control output torque calculation unit 67 for calculating the control output torque Tr of the hydraulic pumps 9 and 10 from the consequent part variable Wij and the combined value μij of the antecedent part, and this control output torque Tr to the electromagnetic proportional pressure reducing valve 14. The control pressure converter 68 is provided for converting the control pressure Ps into a command signal. The antecedent part computing part 63 and the consequent part computing part 66 serve as a fuzzy inference computing part. The function of each unit will be described later.

The operation of the second embodiment will be described next.

(1) Engine output characteristics It is similar to the first embodiment.

(2) Characteristics of hydraulic pump regulator It is similar to the first embodiment.

(3) Hydraulic Pump Control Method FIG. 8 is a block diagram showing a second embodiment of the pump control calculation function in the power unit system controller according to the present invention. The first pump discharge oil amount prediction calculation unit
The functions of 60, the second pump discharge oil amount prediction calculation unit 61, and the total flow rate prediction calculation unit 62 are the same as those of the first pump discharge oil amount prediction calculation unit 50 and the second pump discharge of the first embodiment shown in FIG. Since it is similar to the oil amount prediction calculation unit 51 and the total flow rate prediction calculation unit 52, the description thereof is omitted.

In FIG. 8, the rotational speed error / rotational speed variation calculation unit 64 calculates the rotational speed error ΔNe of the actual engine rotational speed Ne with respect to the engine target rotational speed Nset set by an accelerator dial (not shown), and the actual engine rotational speed. The rotational speed change amount DNe of several Ne per time is calculated by the following formula. Note that, hereinafter, the amount of change in the number of revolutions of the actual engine speed Ne is referred to simply as "the amount of change in the number of revolutions".

ΔNe = Nset−Ne (6) DNe = (Ne (k) 1 Ne (k-1)) / (t (k) −t (k-1)) (7) where (k), (k-1) represents the step on control, (k)
Represents the current step and (k-1) represents the previous step. Also, t is time.

The rotation speed error ΔNe and the rotation speed change amount D
Ne is input to the antecedent part computing part 63 and calculates the degree of conformity of the fuzzy rule to the antecedent part (if-part).

FIG. 9 shows a fuzzy rule. In the table, for the rotational speed error ΔNe, NB, NM, NS,
ZO, PS, PM, and PB are described, and NB, NM, NS, ZO, PS, and
The part described as PM and PB corresponds to the rule of the antecedent part. Wij (i = 1 to 7, j = 1 to 7) in the table is the consequent part variable.

NB is Negative Big, NM is Negative Medi
um, NS is Negative Small, ZO is Zero, PS is Positi
veSmall, PM is Positive Medium, PB is Positive Big
Is an abbreviation for and is called a fuzzy label.

Regarding the rotation speed error ΔNe, NB means that the actual engine speed Ne is considerably larger than the engine target speed Nset, and PB means that the actual engine speed Ne is considerably smaller than the engine target speed Nset. For the rotational speed change amount DNe, NB means that the rotational speed change is negative and large, and PB means that the rotational speed change is positive and large.

The goodness of fit quantitatively represents the goodness of fit to each fuzzy label. In the case of fuzzy control,
The membership function is used for the above quantification.

FIG. 10 shows an example of the membership function, which relates to the rotation speed error ΔNe.
For example, in the case of the antecedent rule of if ΔNe is NM, the membership function (triangle) corresponding to NM in FIG. 10 is used to find the value of the membership function with respect to the rotation speed error ΔNe, and the above value is set to the above value. It is defined as the degree of conformity to the antecedent rule. The same applies to other antecedent rules.

Next, the antecedent part computing part 63 obtains the composite value of the respective antecedent part conformances as follows.

The degree of suitability of the antecedent rule with respect to the rotational speed error ΔNe is μ j, j = 1 to 7 (j = 1 is NB, j = 2).
Corresponds to NM, ..., j = 7 corresponds to PB), and each degree of conformity of the antecedent rule with respect to the rotational speed change amount DNe is μi,
i = 1 to 7 (i = 1 is NB, i = 2 is NM, ..., i
= 7 corresponds to PB), the combined value μ of μ i and μ j
ij is calculated by the following formula.

Μij = μi × μj (8) As a method of calculating the combined value, there is a method of using the following equation other than the above.

[0092]   μij = min (μi, μj) (9) Where min is a function that selects the minimum value.

Then, the first pump discharge oil amount prediction calculation unit 60
Using the pump regulator characteristic of FIG. 4 described above,
From the relief pressure Pr1, the pump discharge pressure Pp, and the command signal of the control pressure Ps of the previous step, the pump discharge flow rate Q1
Predict. The second pump discharge oil amount prediction calculation unit 61 similarly predicts the pump discharge flow rate Q2.

The total flow rate prediction calculation unit 62 calculates the total predicted flow rate Q from the obtained predicted discharge flow rates Q1 and Q2.

Q = Q1 + Q2 (10) In the conversion error calculation unit 65, the rotation speed error ΔNe and the rotation speed change amount DNe output from the rotation speed error / rotation speed change amount calculation unit 64 are output from the total flow rate prediction calculation unit 62. The conversion error Δf is calculated as follows from the output total predicted flow rate Q and the pump discharge pressure Pp.

Δf = ΔNe + m · DNe (11) However, if any one of the following four conditions is not satisfied, Δf = 0 (12) is set.

[Condition] | ΔNe | <α1 | DNe | <α2 | (Pp (k) -Pp (k-1)) / (t (k) -t (k-1)) |
<Α3 | (Q (k) -Q (k-1)) / (t (k) -t (k-1)) | <α
4 Here, m, α1, α2, α3, and α4 are preset constants.

The consequent part calculation unit 66 is supplied with the conversion error Δf output from the conversion error calculation unit 65 and the antecedent part composite value μij output from the antecedent part calculation unit 63. The value of the consequent variable Wij is calculated.

Wij (k) = Wij (k-1) -γ · Δt · Δf · μij (13) where γ is the learning gain, Δt is the control step time, Δf is the conversion error, and μij is the antecedent. It is a goodness-of-fit synthetic value, i = 1
˜7, j = 1˜7.

When the equation (13) is used, the matching degree of the antecedent part rule is high (more antecedent part rule), and the conversion error Δ
The larger f is, the larger the second term of the equation (13) is, and the larger the correction amount for the consequent variable Wij (k-1) of the previous step is. Further, since the second term changes until the conversion error Δf disappears, the consequent part variable Wij is corrected (learned).

The control output torque calculation unit 67 calculates the control output torque Tr of the hydraulic pump by the following equation using the consequent part variable Wij (k) and the antecedent part composite value μij.

Tr = Σ (μij × Wij (k)) / Σμij (14) Formula (14) is a so-called weighted average calculation formula and is a general formula for obtaining the output value of fuzzy control.

The control output torque Tr is converted by the control pressure converter 68 into a command signal of the control pressure Ps for the electromagnetic proportional pressure reducing valve 14.

When the accelerator dial is changed, the engine target speed Nset is also changed. Therefore, in the present invention, the consequent variable Wij is prepared for each accelerator dial, and the learning calculation is performed for each accelerator dial. By doing so, appropriate control (learning) is performed for each accelerator dial.

(4) Effects of the Second Embodiment As described above, according to the second embodiment, the actual engine speed Ne, the pump discharge pressure Pp, and the remote control valves 19, 20 of the operating lever are provided. Since the relief pressures Pr1 and Pr2 corresponding to the operation amounts of the control valves 15 and 17 are input to the controller 21, respectively, the flow rates of the hydraulic pumps 9 and 10 in operation can be accurately predicted, and the lever Immediately after or during fine operation, the engine output and the pump absorption torque are kept in balance and the engine target speed Nse is maintained.
The actual engine speed Ne can be settled stably near t.

Further, the composite value μij of each fitness for each range of the rotational speed error ΔNe and the rotational speed change amount DNe.
And the conversion error Δf calculated from the rotation speed error ΔNe and the rotation speed change amount DNe are used to learn the control output torque Tr of the pump, and therefore, depending on the characteristics of the pump in operation, The control output torque Tr of the hydraulic pumps 9 and 10 can be manipulated according to the rotational speed error ΔNe of the engine 11 and the rotational speed change amount DNe.

That is, the engine rotation accompanying engine characteristics due to changes in pump output state due to hydraulic excavator model, individual differences, changes in working environment (eg cold regions, warm regions, etc.), and changes in engine fuel. Even if the number of dynamic characteristics changes, the control side can learn and control the hydraulic pump according to each hydraulic excavator.

Further, by the learning calculation, even if the model of the hydraulic excavator is different, the same control program can be used, and the work of changing the control program for each model is eliminated.

In each of the embodiments, the relief valve 1 is used as a signal corresponding to the operation amount of the control valves 15 and 17.
Although the relief pressures Pr1 and Pr2 at the inlets of 6 and 18 are indirectly detected, the lever operation amount of the remote control valves 19 and 20 may be directly detected as a signal corresponding to the operation amount of the control valves 15 and 17. .

[0110]

According to the first aspect of the invention, the flow rate of the hydraulic pump during operation can be accurately predicted from the engine speed, the pump discharge pressure, and the operation amount signal of the control valve, and immediately after operating the control valve. Alternatively, the actual engine speed can be made to follow the engine target engine speed without losing the balance between the engine output and the pump absorption torque during fine operation, and the actual engine speed can be settled stably near the engine target engine speed. You can

According to the second aspect of the present invention, the flow rate of the hydraulic pump during operation can be accurately predicted, and the balance between the engine output and the pump absorption torque immediately after the control valve is operated or during the fine operation is not disturbed. The actual engine speed can be made to follow the engine target engine speed. Further, the fuzzy inference is used to calculate the pump control output torque by learning with the product of the goodness of fit for each range of the pump discharge pressure and the total predicted flow rate and the rotational speed error of the actual engine rotational speed with respect to the reference rotational speed. Therefore, the control output torque of the hydraulic pump can be manipulated according to the output state of the pump during operation and the engine speed error. That is, the model of the construction machine,
Even if the output state of the pump changes due to individual differences, the working environment changes, for example, in cold regions or warm regions, or the dynamic characteristics of the engine speed change due to engine characteristics due to changes in engine fuel, learning calculation This enables control of the hydraulic pump according to each construction machine. Further, by the learning calculation, even if the model of the construction machine is different, the same control program can be used, and the work of changing the control program for each model can be eliminated.

According to the third aspect of the invention, the flow rate of the hydraulic pump during operation can be accurately predicted, and the balance between the engine output and the pump absorption torque immediately after operating the control valve or during fine operation is not disturbed. The engine actual speed can be settled stably near the engine target speed. Also, using fuzzy inference, the product of the fitness of the engine speed error and the amount of change in the number of revolutions per time for each range and the conversion error calculated from the error in the number of revolutions and the amount of change in the number of revolutions Since the pump control output is calculated, the control output torque of the hydraulic pump can be manipulated according to the characteristics of the pump during operation, and also according to the engine speed error and the amount of change in speed. In other words, the output state of the pump changes due to the type of construction machine, individual differences,
Even if the dynamic characteristics of the engine speed change due to engine characteristics due to changes in the working environment such as cold regions or warm regions, or changes in engine fuel, the hydraulic pump can be controlled according to each construction machine by learning calculation. become. Further, by the learning calculation, the same control program can be used even if the model of the construction machine is different, and the work of changing the control program for each model can be eliminated.

According to the fourth aspect of the present invention, the engine rotational speed, the pump discharge pressure, and the operation amount of the control valve or a signal corresponding to the operation amount are input to the controller, and the controller operates the hydraulic pump. Of the hydraulic pump, the control output torque of the hydraulic pump is calculated, the output signal of the controller is output to the electro-oil conversion valve, and the pump regulator is controlled by the control pressure, relief pressure and pump discharge pressure output from the electro-oil conversion valve. Since the discharge flow rate adjusting means of the hydraulic pump is controlled by, the flow rate of the hydraulic pump during operation can be accurately predicted, and the balance between the engine output and the pump absorption torque immediately after lever operation or during fine operation can be maintained. To make the actual rotation speed follow the engine target rotation speed, or to stabilize the actual rotation speed near the engine target rotation speed. It can be.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a power unit system according to a control device for a hydraulic pump of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between an engine output characteristic and a target rotational speed when 100% of engine output in the power unit system is used.

FIG. 3 is a characteristic diagram showing a relationship between an engine output characteristic and a target rotational speed when the engine output in the power unit system is set to 100% or less.

FIG. 4 is an explanatory diagram showing characteristics of a pump regulator in the above power unit system.

FIG. 5 is a block diagram showing a first embodiment of a pump control calculation function in the power unit system controller according to the present invention.

FIG. 6 is a table showing a fuzzy rule relating to the first embodiment.

FIG. 7 is an explanatory diagram showing an example of a membership function of a fuzzy rule antecedent part according to the first embodiment.

FIG. 8 is a block diagram showing a second embodiment of the pump control calculation function in the power unit system controller according to the present invention.

FIG. 9 is a diagram showing a fuzzy rule relating to the second embodiment.

FIG. 10 is an explanatory diagram showing an example of a membership function of a fuzzy rule antecedent part according to the second embodiment.

FIG. 11 is a perspective view of a hydraulic excavator.

FIG. 12 is a block diagram showing a conventional power unit system.

[Explanation of symbols]

9,10 Hydraulic pump 9a, 10a Swash plate as means for adjusting discharge flow rate 11 Engine 12, 13 Pump regulator 14 Electromagnetic proportional pressure reducing valve as electric oil conversion valve 15, 17 Control valve 16, 18 Relief valve 21 Controller Pp Pump discharge pressure Pr1, Pr2 Relief pressure Ps control pressure equivalent to control valve control amount Q Total predicted flow rate Nset Engine target speed Nr Engine reference speed Ne Engine actual speed ΔNe speed error DNe Speed change Δf conversion error per hour Tr control output torque

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masumi Nomura 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Heavy Industries, Ltd. (56) References JP-A-10-82402 (JP, A) JP-A-10 -89305 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02F 9/22 F04B 49/00

Claims (4)

(57) [Claims] 1. An engine speed, a pump discharge pressure of pressure oil discharged from a variable displacement hydraulic pump driven by the engine, and a direction and a flow rate of pressure oil supplied from the hydraulic pump to an actuator are controlled. The change in the flow rate of the hydraulic pump during operation is predicted from the signal corresponding to the operation amount of the control valve, and the control output torque of the hydraulic pump is calculated from this predicted change in the flow rate of the hydraulic pump. A method for controlling a hydraulic pump, comprising: controlling the hydraulic pump. 2. A fuzzy reasoning is used to adapt the degree of conformity of the pressure oil discharged from a plurality of hydraulic pumps to each range of the pump discharge pressure and the total predicted flow rate, and the engine actual speed to the reference speed corresponding to the engine target speed. The control output torque of the hydraulic pump is calculated by the product of the rotation speed and the rotation speed error, and the control output torque of the hydraulic pump is operated according to the output state of the hydraulic pump during operation and the engine rotation speed error. The method for controlling a hydraulic pump according to claim 1. 3. Using fuzzy inference, the degree of conformity with respect to each range of the rotational speed error of the actual engine rotational speed with respect to the engine target rotational speed and the rotational speed change amount of the actual engine rotational speed, the rotational speed error and the rotational speed. The control output torque of the hydraulic pump is calculated by the product of the conversion error calculated from the number change amount, and the control output of the hydraulic pump is calculated according to the characteristics of the operating hydraulic pump, the engine speed error and the engine speed change amount. The method for controlling a hydraulic pump according to claim 1, wherein the torque is operated. 4. An engine, a plurality of variable displacement hydraulic pumps driven by the engine, a plurality of control valves for controlling the direction and flow rate of pressure oil discharged from these hydraulic pumps, and these controls. From a plurality of relief valves that set the pressure of the pressure oil supplied to the actuator via the valve, the engine speed, the pump discharge pressure of the pressure oil discharged from the hydraulic pump, and the relief pressure at the inlet of the relief valve, A controller that predicts the flow rate change of the hydraulic pump during operation, calculates the control output torque of the hydraulic pump and outputs it, an electro-hydraulic conversion valve that converts the output signal of this controller into control pressure, control pressure, relief pressure and And a pump regulator for controlling the discharge flow rate adjusting means of the hydraulic pump according to the pump discharge pressure. Control device for hydraulic pump.