JP6814440B2 - Work machine - Google Patents

Description

The present invention relates to a working machine.

Work machines such as hydraulic excavators are equipped with a hydraulic system for driving a hydraulic actuator. The hydraulic system includes a hydraulic pump driven by an engine, and a hydraulic actuator is driven by hydraulic oil discharged from the hydraulic pump. Therefore, the operation of the hydraulic system is affected by the viscosity of the hydraulic oil.

For example, in a low temperature environment such as winter, the viscosity of the hydraulic oil becomes high. Therefore, the reaction of the pump regulator that controls the discharge flow rate of the hydraulic pump becomes slow, and the response of the hydraulic pump to the flow rate command is delayed. As a result, when so-called PQ control is being performed, if the fluctuation range of the discharge flow rate with respect to the fluctuation range of the pump pressure is considerably large, hunting is likely to occur. The PQ control is a control method for determining a command value (target discharge flow rate) of the discharge flow rate of the hydraulic pump from the measured pump pressure based on a pressure-flow rate curve (PQ curve) obtained from a desired load torque. Is.

In the pump control device for construction machinery described in Patent Document 1 below, in order to prevent hunting at low temperatures, when the temperature of the hydraulic oil does not reach the set temperature, when the temperature of the hydraulic oil is equal to or higher than the set temperature. The load torque of the hydraulic pump is lower than that.

JP-A-2002-364603

In the pump control device for construction machinery described in Patent Document 1, the load torque of the hydraulic pump is changed according to the temperature of the hydraulic oil. Therefore, depending on the temperature of the hydraulic oil, the hydraulic actuator cannot obtain the desired output.

An object of the present invention is to provide a work machine capable of suppressing a delay in response of a hydraulic pump to a flow rate command while ensuring a load torque of the hydraulic pump even when the viscosity of the hydraulic oil is high. ..

In order to achieve the above object, the inventor of the present application has focused on PID control using a dynamic compensator instead of PQ control using a static compensator. As a result, it has been found that it is difficult to make the load torque of the hydraulic pump follow the target load torque, although it is possible to suppress the response delay of the hydraulic pump to the flow rate command by using PID control.

Therefore, the inventor of the present application has investigated the cause of difficulty in making the load torque of the hydraulic pump follow the target load torque. As a result, it has been found that it becomes difficult to make the load torque of the hydraulic pump follow the target load torque because the integral element of the PID control is canceled by the differential element of the hydraulic system.

Here, in order to make it easier for the load torque of the hydraulic pump to follow the target load torque, it is conceivable to adopt a controller having a double integral element as the controller used for calculating the target discharge flow rate. However, if it has a double integral element, the load when calculating the target discharge flow rate becomes excessive.

As a result of further studies based on such findings, the inventor of the present application has noticed that the double integral factor should be considered in the calculation of the target discharge flow rate only in specific cases. Specifically, I noticed that the double integral factor should be taken into consideration when calculating the target discharge flow rate in a state where the viscosity of the hydraulic oil is high and PQ control is performed. .. The present invention has been completed based on such findings.

The working machine according to the present invention includes an engine, a hydraulic pump driven by the engine, a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump, a pump regulator for adjusting the discharge flow rate of the hydraulic pump, and the above. An operating device operated by an operator of a working machine to drive the hydraulic actuator, a temperature detecting device for detecting the temperature of the hydraulic oil, and a hydraulic detection device for detecting the pressure of the hydraulic oil discharged by the hydraulic pump. A load torque acquisition device that acquires the load torque of the hydraulic pump, and a control device that controls the operation of the hydraulic pump by controlling the operation of the pump regulator. The control device is the operation device. A target load torque setting unit that sets the target load torque of the hydraulic pump according to the operation amount of the hydraulic pump, and a target load torque determination unit that determines whether or not the target load torque is smaller than a predetermined reference load torque. A detection temperature determination unit that determines whether or not the temperature of the hydraulic oil detected by the temperature detection device is lower than a predetermined reference temperature, a discharge flow rate calculation unit that calculates a target discharge flow rate of the hydraulic pump, and the above. The discharge flow rate calculation unit includes a regulator control unit that controls the operation of the pump regulator so that the discharge flow rate of the hydraulic pump becomes the target discharge flow rate, and the discharge flow rate calculation unit sets the target load torque as the target discharge flow rate. When it is smaller than the reference load torque of, the first target discharge flow rate is calculated so that the load torque becomes the target load torque, and the target load torque is greater than or equal to the predetermined reference load torque. Moreover, when the temperature of the hydraulic oil is equal to or higher than the predetermined reference temperature, the load torque becomes the predetermined reference load torque according to the pressure of the hydraulic oil detected by the hydraulic pressure detection device. When the target load torque is greater than or equal to the predetermined reference load torque and the temperature of the hydraulic oil is lower than the predetermined reference temperature, the second target discharge flow rate is calculated. The load torque is determined based on the proportional differential leading type PID control using the difference between the target load torque and the load torque acquired by the load torque acquisition device and the double integration of the difference. Calculate the third target discharge flow rate that will be the reference load torque.

In the above-mentioned work machine, PID control using a dynamic controller is performed when calculating the third target discharge flow rate. Therefore, as compared with PQ control using a static controller, it is possible to avoid a delay in the response of the hydraulic pump to the flow rate command even when the viscosity of the hydraulic oil is high.

Further, in the above-mentioned work machine, when calculating the third target discharge flow rate, not only the proportional differential leading type PID control using the difference between the target load torque and the load torque acquired by the load torque acquisition device is also used. Double integration of the difference is also performed. Therefore, it becomes easy to make the load torque of the hydraulic pump follow the target load torque. As a result, the load torque of the hydraulic pump can be secured.

In particular, in the above-mentioned work machine, since the proportional differentiation preceding type PID control (so-called I-PD control) is performed, the input value kick (that is, the target load as the target value) is performed as compared with the case where the normal PID control is performed. It is possible to suppress a sudden increase in the input value caused by fluctuations in torque).

In the work machine, preferably, the discharge flow rate calculation unit performs the PID controller that performs the calculation by the proportional differentiation preceding type PID control, the double integral that performs the double integration, and the double integration. The double integral gain acquisition unit includes a double integral gain acquisition unit that acquires a double integral gain that is multiplied by the double integral value obtained by the above, and the double integral gain acquisition unit is a hydraulic oil detected by the hydraulic detector. The double integral gain is acquired according to the pressure.

In the above aspect, the double integral gain is acquired according to the detected hydraulic oil pressure. Therefore, a more appropriate target discharge flow rate can be calculated.

In the work machine, preferably, the discharge flow rate calculation unit further calculates a control gain used for the proportional differential preceding type PID control according to the oil pressure of the hydraulic oil detected by the hydraulic pressure detection device. Includes control gain calculation unit.

In the above aspect, the control gain used for the proportional differential leading type PID control is calculated according to the detected hydraulic oil pressure. Therefore, a more appropriate target discharge flow rate can be calculated.

In the work machine, preferably, the discharge flow rate calculation unit resets the result of the double integral when calculating either the first target discharge flow rate or the second target discharge flow rate. Includes reset section.

In the above aspect, when the third target discharge flow rate is not calculated, the double integral value as a result of the double integral is reset, so that it is possible to prevent the double integral value from being continuously accumulated. it can. As a result, an appropriate target discharge flow rate can be calculated when the next third target discharge flow rate is calculated.

In the working machine, preferably, the control device further includes a discharge flow rate estimation unit that estimates the discharge flow rate of the hydraulic pump according to the temperature of the hydraulic oil detected by the temperature detection device, and the load torque. The acquisition device acquires the load torque of the hydraulic pump based on the discharge flow rate of the hydraulic pump estimated by the discharge flow rate estimation unit and the pressure of the hydraulic oil detected by the hydraulic detection device.

In the above aspect, it is not necessary to actually detect the load torque of the hydraulic pump when the calculation of the third target discharge flow rate is performed. Therefore, it is not necessary to separately provide a device for detecting the load torque of the hydraulic pump.

According to the work machine according to the present invention, even when the viscosity of the hydraulic oil is high, it is possible to suppress the delay in the response of the hydraulic pump to the flow rate command while ensuring the load torque of the hydraulic pump.

It is explanatory drawing which shows the main component of the work machine by embodiment of this invention. It is a block diagram which shows a controller. It is a block diagram which shows the discharge flow rate calculation part. It is a block diagram which shows the 3rd discharge flow rate calculation part. It is a block diagram which shows the double integral gain acquisition part. It is a flowchart which shows the operation control of a hydraulic pump. It is a block diagram which shows the discharge flow rate calculation part adopted in application example 1 of the Embodiment of this invention. It is a flowchart which shows the operation control of the hydraulic pump in the application example 1 of the Embodiment of this invention. It is a block diagram which shows the 3rd discharge flow rate calculation part adopted in the application example 2 of the Embodiment of this invention. It is a flowchart which shows the operation control of the hydraulic pump in the application example 2 of the Embodiment of this invention. It is a block diagram which shows the controller adopted in the application example 3 of the Embodiment of this invention. It is a graph which shows the simulation result of the load torque of the hydraulic pump when the operation control which concerns on an Example is performed. It is a graph which shows the simulation result of the discharge flow rate of the hydraulic pump when the operation control which concerns on an Example is performed. It is a graph which shows the simulation result of the pressure of hydraulic oil when the operation control which concerns on an Example is performed. It is a graph which shows the simulation result of the load torque of the hydraulic pump when the operation control which concerns on Comparative Example 1 is performed. It is a graph which shows the simulation result of the discharge flow rate of the hydraulic pump when the operation control which concerns on Comparative Example 1 is performed. It is a graph which shows the simulation result of the pressure of hydraulic oil at the time of performing the operation control which concerns on Comparative Example 1. It is a graph which shows the simulation result of the load torque of the hydraulic pump when the operation control which concerns on Comparative Example 2 is performed. It is a graph which shows the simulation result of the discharge flow rate of the hydraulic pump when the operation control which concerns on Comparative Example 2 is performed. It is a graph which shows the simulation result of the pressure of hydraulic oil when the operation control which concerns on Comparative Example 2 is performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The working machine 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram showing the main components of the work machine 10.

The work machine 10 has, for example, a structure in which an upper swing body is arranged so as to be swivel with respect to a lower traveling body. The work machine 10 is, for example, a hydraulic excavator including a hydraulic system.

The work machine 10 includes an engine 12, a hydraulic pump 14, a regulator 16 as a pump regulator, a proportional valve 18, a hydraulic actuator 20, a control valve 22, a remote control valve 24, a relief valve 26, and a hydraulic pressure detection device. The pump pressure sensor 28, the pilot pressure sensor 30, the temperature sensor 32 as the temperature detection device, the torque sensor 34 as the load torque acquisition device, and the controller 40 as the control device are provided.

The engine 12 is a drive source for the work machine 10. The engine 12 may include, for example, a supercharger.

The hydraulic pump 14 is driven by the engine 12 and discharges hydraulic oil. The hydraulic pump 14 is a variable displacement hydraulic pump. The hydraulic pump 14 has a variable tilt angle. The discharge flow rate of the hydraulic pump 14 is controlled by adjusting the tilt angle by the regulator 16 and the proportional valve 18.

The hydraulic actuator 20 is driven by the hydraulic oil discharged from the hydraulic pump 14 (that is, the hydraulic oil supplied from the hydraulic pump 14). The hydraulic actuator 20 may be, for example, a hydraulic motor or a hydraulic cylinder. The hydraulic motor may be, for example, a traveling motor or a swivel motor. The hydraulic cylinder may be, for example, a boom cylinder, an arm cylinder, or a bucket cylinder.

The control valve 22 changes the direction and flow rate of the hydraulic oil supplied from the hydraulic pump 14 to the hydraulic actuator 20. The control valve 22 is, for example, a pilot operation switching valve at three positions having first and second pilot ports, and is driven by inputting pilot pressure to the first and second pilot ports.

The remote control valve 24 is operated to switch the operating state of the control valve 22. The remote control valve 24 includes an operation lever 24A as an operation device and a valve body 24B. The valve body 24B outputs a pilot pressure for operating the control valve 22 based on the operation given to the operating lever 24A.

The relief valve 26 opens and closes so that the pressure of the hydraulic oil discharged from the hydraulic pump 14 does not exceed a predetermined pressure.

The pump pressure sensor 28 detects the pump pressure, which is the pressure of the hydraulic oil discharged from the hydraulic pump 14. A signal related to the pump pressure (pump pressure signal) detected by the pump pressure sensor 28 is input to the controller 40.

The pilot pressure sensor 30 detects the pilot pressure of the remote control valve 24 as information regarding the presence / absence of an operation given to the operation lever 24A and the operation amount thereof. A signal (lever operation signal) relating to the pilot pressure of the remote control valve 24 detected by the pilot pressure sensor 30 is input to the controller 40.

The temperature sensor 32 detects the temperature of the hydraulic oil. A signal (temperature signal) relating to the temperature of the hydraulic oil detected by the temperature sensor 32 is input to the controller 40.

The torque sensor 34 detects the load torque of the hydraulic pump 14. Here, the load torque of the hydraulic pump 14 is the torque given to the hydraulic pump 14 from the engine 12. A signal (load torque signal) related to the load torque of the hydraulic pump 14 detected by the torque sensor 34 is input to the controller 40.

The controller 40 controls the operation of the hydraulic pump 14 by controlling the operation of the pump regulator 16.

The controller 40 is realized, for example, by the central processing unit reading a program stored in the storage device and performing a predetermined process. At least a part of the controller 40 may be realized by an integrated circuit such as an ASIC.

The controller 40 will be described with reference to FIG. FIG. 2 is a block diagram showing the controller 40.

The controller 40 includes a target load torque setting unit 41, a target load torque determination unit 42, a detection temperature determination unit 43, a discharge flow rate calculation unit 44, a regulator control unit 45, and a detection pressure determination unit 46.

The target load torque setting unit 41 sets the target load torque of the hydraulic pump 14 according to the operation amount of the operation lever 24A. Specifically, the target load torque setting unit 41 sets the target load torque of the hydraulic pump 14 according to the pilot pressure of the remote control valve 24 detected by the pilot pressure sensor 30. The target load torque of the hydraulic pump 14 may be set, for example, by using a reference table or by performing a predetermined calculation.

The target load torque determination unit 42 determines whether or not the target load torque is smaller than a predetermined reference load torque. The reference load torque is, for example, the load torque when the performance of the engine 12 is maximized.

The detection temperature determination unit 43 determines whether or not the temperature of the hydraulic oil detected by the temperature sensor 32 is lower than a predetermined reference temperature. The reference temperature is, for example, the temperature when the viscosity of the hydraulic oil is low. The reference temperature is, for example, 30 ° C.

The discharge flow rate calculation unit 44 calculates the target discharge flow rate of the hydraulic pump 14. The details of the discharge flow rate calculation unit 44 will be described later.

The regulator control unit 45 controls the operation of the regulator 16 so that the discharge flow rate of the hydraulic pump 14 becomes the target discharge flow rate calculated by the discharge flow rate calculation unit 44. Specifically, a flow rate command corresponding to the target discharge flow rate calculated by the discharge flow rate calculation unit 44 is generated, and the operation of the regulator 16 is controlled by the flow rate command.

The discharge flow rate calculation unit 44 will be described with reference to FIG. FIG. 3 is a block diagram showing a discharge flow rate calculation unit 44.

The discharge flow rate calculation unit 44 includes a first discharge flow rate calculation unit 441, a second discharge flow rate calculation unit 442, and a third discharge flow rate calculation unit 443.

The first discharge flow rate calculation unit 441 calculates the first target discharge flow rate as the target discharge flow rate when the target load torque set by the target load torque setting unit 41 is smaller than the predetermined reference load torque. The first target discharge flow rate is a discharge flow rate such that the load torque of the hydraulic pump 14 becomes the target load torque set by the target load torque setting unit 41. In short, the first target discharge flow rate is a target discharge flow rate set for so-called positive control.

In the second discharge flow rate calculation unit 442, the target load torque set by the target load torque setting unit 41 is greater than or equal to a predetermined reference load torque, and the temperature of the hydraulic oil detected by the temperature sensor 32 is When the temperature is equal to or higher than the predetermined reference temperature, the second target discharge flow rate is calculated as the target discharge flow rate. The second target discharge flow rate is a discharge flow rate calculated from the pump pressure detected by the pump pressure sensor 28 based on a pressure-flow rate curve (PQ curve) obtained from a predetermined reference load torque. In short, the second target discharge flow rate is a target discharge flow rate set for so-called PQ control.

In the third discharge flow rate calculation unit 443, the target load torque set by the target load torque setting unit 41 is greater than or equal to a predetermined reference load torque, and the temperature of the hydraulic oil detected by the temperature sensor 32 is When the temperature is lower than the predetermined reference temperature, the third target discharge flow rate is calculated as the target discharge flow rate. The third target discharge flow rate is calculated based on the calculation result using the difference between the target load torque set by the target load torque setting unit 41 and the load torque of the hydraulic pump 14 detected by the torque sensor 34. Is. The third target discharge flow rate is calculated based on the following equation (1).

Here, Q (t) is a target discharge flow rate (command value of the discharge flow rate). T (t) is the load torque. Kp (t) is a proportional gain. Ki (t) is the integral gain. Kd (t) is a differential gain. e (t) is the difference (Tr (t) −T (t)) between the target load torque Tr (t) and the load torque T (t). Kii (t) is a double integral gain. Σe (t) is a double integral value (calculation result by a double integral).

The proportional gain Kp (t), the integrated gain Ki (t), and the differential gain Kd (t) are calculated based on, for example, the generalized minimum dispersion control law (GMVC law). The calculation of the double integral gain Kii (t) will be described later.

The third discharge flow rate calculation unit 443 will be described with reference to FIG. FIG. 4 is a block diagram showing a third discharge flow rate calculation unit 443.

The third discharge flow rate calculation unit 443 includes a PID controller 4431, a double integral unit 4432, and a double integral gain acquisition unit 4433.

The PID controller 4431 uses PID control using the difference (e (t) above) between the target load torque set by the target load torque setting unit 41 and the load torque of the hydraulic pump 14 detected by the torque sensor 34. The first calculation result is calculated by performing the calculation according to. Here, the PID control performed by the PID controller is a proportional differentiation leading type PID control. The PID controller 4431 calculates the first calculation result by using the mathematical formulas of the first to fourth terms in the above formula (1).

The double integral 4432 double-integrates the difference (the above e (t)) between the target load torque set by the target load torque setting unit 41 and the load torque of the hydraulic pump 14 detected by the torque sensor 34. Then, the double integral value (Σe (t) described above) is calculated.

The double integral gain acquisition unit 4433 acquires the double integral gain (Kii (t) described above) to be multiplied by the double integral value as the calculation result by the double integral 4432.

The third discharge flow rate calculation unit 443 calculates the second calculation result obtained by multiplying the double integral gain acquired by the double integral gain acquisition unit 4433 by the double integral value calculated by the double integral 4432. calculate. The second calculation result is calculated by using the formula of the fifth term in the above formula (1). Then, the third discharge flow rate calculation unit 443 calculates the third target discharge flow rate by adding the second calculation result calculated in this way to the calculation result (first calculation result) by the PID controller 4431. ..

The double integral gain acquisition unit 4433 will be described with reference to FIG. FIG. 5 is a block diagram showing a double integral gain acquisition unit 4433.

The double integral gain acquisition unit 4433 includes a double integral gain calculation unit 4434 and a double integral gain selection unit 4435.

The double integral gain calculation unit 4434 calculates the double integral gain when the pressure of the hydraulic oil detected by the pump pressure sensor 28 is equal to or less than a predetermined reference pressure. The reference pressure may be, for example, the pressure when the relief valve 26 is operating (relief pressure) or the pressure near the relief pressure (for example, a pressure of 97% of the relief pressure).

When the pressure of the hydraulic oil detected by the pump pressure sensor 28 is P2 or more and P1 or less, the double integral gain calculation unit 4434 calculates the double integral gain using the following equation (2). To do. P1 is the reference pressure. P2 is the pressure when the relief valve 26 is not operating (for example, a pressure of 70% of the relief pressure).

In the above equation (2), K _II1 is the double integral gain when the pressure is P1. K _II2 is the double integral gain when the pressure is P2.

When the pressure is lower than P2, the double integral gain calculation unit 4434 calculates K _II2 as the double integral gain.

The above-mentioned double integral gains K _II1 and K _II2 are calculated based on, for example, the generalized minimum dispersion control law (GMVC law).

The double integral gain selection unit 4435 selects a predetermined double integral gain when the pressure of the hydraulic oil detected by the pump pressure sensor 28 is higher than the predetermined reference pressure. The predetermined double integral gain is, for example, zero.

The operation control of the hydraulic pump 14 by the controller 40 will be described with reference to FIG. FIG. 6 is a flowchart showing the operation control of the hydraulic pump 14.

First, in step S11, the controller 40 determines whether or not the target load torque set by the target load torque setting unit 41 is equal to or greater than a predetermined reference load torque.

When the target load torque is smaller than the reference load torque (step S11: NO), the controller 40 calculates the first target discharge flow rate in step S12. After that, the controller 40 executes the processes after step S19, which will be described later. Specifically, the regulator 16 is driven based on the first target discharge flow rate calculated in step S12.

When the target load torque is equal to or higher than the reference load torque (step S11: YES), the controller 40 determines in step S13 whether or not the temperature of the hydraulic oil detected by the temperature sensor 32 is equal to or higher than the predetermined reference temperature. To do.

When the temperature of the hydraulic oil is equal to or higher than the reference temperature (step S13: YES), the controller 40 calculates the second target discharge flow rate in step S14. After that, the controller 40 executes the processes after step S19, which will be described later. Specifically, the regulator 16 is driven based on the second target discharge flow rate calculated in step S14.

When the temperature of the hydraulic oil is lower than the reference temperature (step S13: NO), the controller 4-determines in step S15 whether or not the pump pressure detected by the pump pressure sensor 28 is equal to or higher than the predetermined reference pressure. To do.

When the pump pressure is lower than the reference pressure (step S15: NO), the controller 40 calculates the double integral gain in step S16. Subsequently, in step S17, the controller 40 calculates the third target discharge flow rate by using the double integral gain calculated in step S16. Subsequently, in step S18, the controller 40 drives the regulator 16 based on the third target discharge flow rate calculated in step S17. After that, the controller 40 ends the operation control of the hydraulic pump 14.

When the pump pressure is equal to or higher than the reference pressure (step S15: YES), the controller 40 selects a predetermined double integral gain in step S19. Subsequently, the controller 40 executes the processes after step S17. Specifically, the third target discharge flow rate is calculated using the double integral gain selected in step S19, and the regulator 16 is driven based on the third target discharge flow rate.

In such a work machine 10, the target load torque set by the target load torque setting unit 41 is greater than or equal to a predetermined reference load torque, and the temperature of the hydraulic oil detected by the temperature sensor 32 is When the temperature is lower than the predetermined reference temperature (that is, when a large load torque is required even though the viscosity of the hydraulic oil is high), the third target discharge flow rate is calculated as the target discharge flow rate. .. When calculating the third target discharge flow rate, the calculation result by the PID controller 4431 (first calculation result) and the calculation result using the double integral value by the double integrator 4432 (second calculation result) are obtained. Used.

Here, the PID controller 4431 functions as a dynamic controller. Therefore, as compared with PQ control using a static controller, it is possible to avoid a delay in the response of the hydraulic pump to the flow rate command even when the viscosity of the hydraulic oil is high.

Further, since the double integral value by the double integrator 4432 is used when calculating the third target discharge flow rate, the load torque of the hydraulic pump 14 can be easily made to follow the target load torque. As a result, the load torque of the hydraulic pump 14 can be secured.

In addition, in the work machine 10, the double integral gain used when calculating the second calculation result is different depending on the operating state of the relief valve 26. Therefore, a more appropriate third target discharge flow rate can be calculated. The reason is as follows.

In the work machine 10, the characteristics of the hydraulic system fluctuate according to the operating state of the relief valve 26. Specifically, when the relief valve 26 is operating, the pressure inside the pipes constituting the hydraulic system becomes constant, so that the hydraulic system of the work machine 10 is treated as a primary delay + waste time system. be able to. On the other hand, when the relief valve 26 is not operating, the hydraulic system of the work machine 10 is a system including a differential element. It should be noted that the system includes a differential element only when the movement of the hydraulic actuator 20 is accelerating. That is, the hydraulic system of the work machine 10 is a system having a piecewise differential element.

The work machine 10 uses a predetermined double integral gain selected by the double integral gain selection unit 4435 when the relief valve 26 is operating. On the other hand, when the relief valve 26 is not operating, the double integral gain calculated by the double integral gain calculation unit 4434 is used. That is, in the work machine 10, the double integral gain used when calculating the third target discharge flow rate (specifically, the second calculation result) is different depending on the characteristics of the hydraulic system. Therefore, a more appropriate third target discharge flow rate can be calculated.

Here, when the predetermined double integral gain selected by the double integral gain selection unit 4435 is zero, when the relief valve 26 is not operating, when calculating the third target discharge flow rate, the first Only the calculation results are used. Therefore, a more appropriate third target discharge flow rate can be calculated.

[Application Example 1 of the Embodiment]
An application example 1 of the embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is a block diagram showing a discharge flow rate calculation unit 44A adopted in Application Example 1.

The application example 1 is different from the above embodiment in that the discharge flow rate calculation unit 44A is adopted instead of the discharge flow rate calculation unit 44. The discharge flow rate calculation unit 44A is different from the discharge flow rate calculation unit 44 in that the calculation result reset unit 444 is provided.

The calculation result reset unit 444 resets the calculation result (double integral value) by the double integrator 4432 when the target discharge flow rate is calculated by the first discharge flow rate calculation unit 441 or the second discharge flow rate calculation unit 442. To do.

The operation control of the hydraulic pump 14 in Application Example 1 will be described with reference to FIG. FIG. 8 is a flowchart showing the operation control of the hydraulic pump 14 in Application Example 1.

The operation control of the hydraulic pump 14 in Application Example 1 is either the calculation of the first target discharge flow rate in step S12 or the calculation of the second target discharge flow rate in step S14, as compared with the operation control of the hydraulic pump 14 in the above embodiment. It differs only in that the calculation result (double integral value) by the double integrator 4432 is reset (step S20) after the pumping is performed and before the regulator 16 is driven in step S18. ..

In such application example 1, the same effect as that of the above embodiment can be obtained.

In addition, in the above application example 1, when the target discharge flow rate is not calculated by the third discharge flow rate calculation unit 443 (calculation of the third target discharge flow rate), the calculation result by the double integrator 4432 (double). (Integral value) is reset. Therefore, it is possible to prevent the calculation result (double integral value) by the double integrator 4432 from being continuously accumulated. As a result, an appropriate target discharge flow rate can be calculated when the target discharge flow rate is calculated (calculation of the third target discharge flow rate) by the third discharge flow rate calculation unit 443 next time.

[Application example 2 of the embodiment]
Application example 2 of the embodiment of the present invention will be described with reference to FIG. FIG. 9 is a block diagram showing a third discharge flow rate calculation unit 443A adopted in Application Example 2.

The application example 2 is different from the above embodiment in that the third discharge flow rate calculation unit 443A is adopted instead of the third discharge flow rate calculation unit 443. The third discharge flow rate calculation unit 443A is different from the third discharge flow rate calculation unit 443 in that the control gain calculation unit 4436 is provided.

The control gain calculation unit 4436 calculates the proportional gain, the integral gain, and the differential gain according to the pump pressure detected by the pump pressure sensor 28.

The proportional gain is calculated using the following equation (3) when the pump pressure detected by the pump pressure sensor 28 is P2 or more and P1 or less.

Here, K _P1 is a proportional gain when the pressure is P1. K _P2 is a proportional gain when the pressure is P2.

When the pressure is lower than P2, the control gain calculation unit 4436 calculates K _P2 as a proportional gain. When the pressure is higher than P1, the control gain calculation unit 4436 calculates K _P1 as a proportional gain.

The proportional gains K _P1 and K _P2 described above are calculated based on, for example, the generalized minimum dispersion control law (GMVC law).

The integrated gain is calculated using the following equation (4) when the pump pressure detected by the pump pressure sensor 28 is P2 or more and P1 or less.

Here, _KI1 is the integrated gain when the pressure is P1. _KI2 is the integrated gain when the pressure is P2.

Incidentally, if the pressure is lower than P2, the control gain calculating unit 4436, as the integral _gain, to calculate the _{K I2.} If the pressure is higher than P1, the control gain calculating unit 4436, as the integral _gain, to calculate the _{K I1.}

Integral gain _{K I1} and _{K I2} described above, for example, is calculated based on the generalized minimal variance control law (GMVC law).

The differential gain is calculated using the following equation (5) when the pump pressure detected by the pump pressure sensor 28 is P2 or more and P1 or less.

Here, _KD1 is a differential gain when the pressure is P1. _KD2 is the differential gain when the pressure is P2.

Incidentally, if the pressure is lower than P2, the control gain calculating unit 4436, as the differential _gain, to calculate the _{K D2.} If the pressure is higher than P1, the control gain calculating unit 4436, as the differential _gain, to calculate the _{K D1.}

Derivative gain _{K D1} and _{K D2} described above, for example, is calculated based on the generalized minimal variance control law (GMVC law).

The operation control of the hydraulic pump 14 in Application Example 2 will be described with reference to FIG. FIG. 10 is a flowchart showing the operation control of the hydraulic pump 14 in Application Example 2.

In the operation control of the hydraulic pump 14 in the application example 2, either the calculation of the double integral gain in step S16 or the selection of the double integral gain in step S19 is performed as compared with the operation control of the hydraulic pump 14 in the above embodiment. Proportional gain, integrated gain, and differential gain are calculated according to the pump pressure detected by the pump pressure sensor 28 after this is performed and before the calculation of the third target discharge flow rate in step S17 is performed. It differs only in that (step S21).

In such Application Example 2, the same effect as that of the above-described embodiment can be obtained.

In addition, in the above application example 2, proportional gain, integral gain, and differential gain are calculated according to the pump pressure detected by the pump pressure sensor 28. Therefore, a more appropriate third target discharge flow rate can be calculated.

[Application Example 3 of the Embodiment]
An application example 3 of the embodiment of the present invention will be described with reference to FIG. FIG. 11 is a block diagram showing a controller 40 adopted in Application Example 3.

The third application is different from the above embodiment in that the controller 40A is adopted instead of the controller 40. The controller 40A is different from the controller 40 in that it includes a discharge flow rate estimation unit 47 and a load torque acquisition unit 48.

The discharge flow rate estimation unit 47 estimates the discharge flow rate of the hydraulic pump 14 according to the temperature of the hydraulic oil detected by the temperature sensor 32. Specifically, it is as follows.

First, a time delay factor for the discharge flow rate of the hydraulic pump 14 to reach the target discharge flow rate is set in advance for each temperature of the hydraulic oil. For example, the relationship between the actually measured delay time (time until the discharge flow rate of the hydraulic pump 14 reaches the target discharge flow rate) and the temperature of the hydraulic oil is stored in a storage device (not shown). Then, the discharge flow rate of the hydraulic pump 14 is estimated by using the delay time according to the temperature of the hydraulic oil detected by the temperature sensor 32. For the estimation of the discharge flow rate of the hydraulic pump 14, for example, a first-order lag approximation is used.

The load torque acquisition unit 48 is based on a calculation result obtained by multiplying the discharge flow rate of the hydraulic pump 14 estimated by the discharge flow rate estimation unit 47 and the pump pressure detected by the pump pressure sensor 28, and the hydraulic pump 14 Get the load torque of. That is, in Application Example 3, the load torque acquisition unit 48 functions as a load torque acquisition device. Therefore, in Application Example 3, the torque sensor 34 becomes unnecessary.

In such an application example 3, the same effect as that of the above embodiment can be obtained.

In addition, in Application Example 3, the load torque of the hydraulic pump 14 can be acquired without the torque sensor 34.

A simulation was performed on the operation control of the hydraulic system provided in the hydraulic excavator as a work machine according to the embodiment of the present invention in a low temperature state. Specifically, a simulation was performed for operation control for keeping the load torque of the hydraulic pump constant when the upper swing body of the hydraulic excavator turns with respect to the lower traveling body (Example). At that time, the proportional gain, the integrated gain, the double integrated gain, and the differential gain were set for each of the state in which the relief valve was opened and the state in which the relief valve was closed, as shown in Table 1 below. When calculating these gains, the calculation result based on the generalized minimum dispersion control law (GMVC law) and the control gain of Comparative Example 2 described later were used.

The simulation result for the load torque of the hydraulic pump is shown in FIG. 12A. The simulation result for the discharge flow rate of the hydraulic pump is shown in FIG. 12B. The simulation result about the pump pressure (the pressure of the hydraulic oil discharged from the hydraulic pump) is shown in FIG. 12C. In FIG. 12A, the target load torque Tr (t) is shown by a broken line.

Further, for comparison, as the operation control for keeping the load torque of the hydraulic pump constant when the upper swing body of the hydraulic excavator turns with respect to the lower traveling body, the case of PQ control (Comparative Example 1) and the PID control A simulation was also performed in the case of (Comparative Example 2). The simulation results of Comparative Example 1 are shown in FIGS. 13A, 13B and 13C. The simulation results of Comparative Example 2 are shown in FIGS. 14A, 14B and 14C.

It was confirmed that in the examples, hunting due to the delay in the response of the hydraulic pump to the flow rate command can be suppressed as compared with the comparative example 1. Further, in the example, it was confirmed that the load torque of the hydraulic pump can be secured by improving the followability of the load torque of the hydraulic pump to the target load torque as compared with the comparative example 2. ..

Although the embodiments of the present invention have been described in detail above, these are merely examples, and the present invention is not to be interpreted in a limited manner by the above description of the embodiments.

In the present invention, the working machine is not particularly limited as long as it can perform a predetermined work. The work machine is, for example, a self-propelled work machine. The self-propelled work machine includes, for example, a lower traveling body and an upper rotating body. The work machine is, for example, a hydraulic work machine. The hydraulic work machine is, for example, a hydraulic excavator.

In the present invention, the work machine may be manned or unmanned.

In the present invention, the load torque acquisition device is not particularly limited as long as it acquires the load torque of the hydraulic pump. The load torque may be directly detected and acquired, or may be acquired by estimating from the measurement data.

10 Work machine 12 Engine 14 Hydraulic pump 16 Regulator 20 Hydraulic actuator 24A Operating lever 28 Pump pressure sensor 32 Temperature sensor 34 Torque sensor 40 Controller 41 Target load torque setting unit 42 Target load torque determination unit 43 Detection temperature determination unit 44 Discharge flow rate calculation unit 441 1st discharge flow rate calculation unit 442 2nd discharge flow rate calculation unit 443 3rd discharge flow rate calculation unit 4431 PID controller 4432 Double integration gain acquisition unit 4436 Control gain calculation unit 4436 Calculation result reset unit 45 Regulator control Unit 46 Detection pressure determination unit 47 Discharge flow rate estimation unit

Claims (5)

It ’s a work machine,
With the engine
The hydraulic pump driven by the engine and
A hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump and
A pump regulator that adjusts the discharge flow rate of the hydraulic pump,
An operating device operated by the operator of the work machine to drive the hydraulic actuator, and
A temperature detection device that detects the temperature of the hydraulic oil, and
A hydraulic detection device that detects the pressure of the hydraulic oil discharged by the hydraulic pump, and
A load torque acquisition device that acquires the load torque of the hydraulic pump, and
A control device for controlling the operation of the hydraulic pump by controlling the operation of the pump regulator is provided.
The control device is
A target load torque setting unit that sets a target load torque of the hydraulic pump according to the amount of operation of the operating device, and a target load torque setting unit.
A target load torque determination unit that determines whether or not the target load torque is smaller than a predetermined reference load torque,
A detection temperature determination unit that determines whether or not the temperature of the hydraulic oil detected by the temperature detection device is lower than a predetermined reference temperature.
A discharge flow rate calculation unit that calculates the target discharge flow rate of the hydraulic pump,
A regulator control unit that controls the operation of the pump regulator so that the discharge flow rate of the hydraulic pump becomes the target discharge flow rate is included.
The discharge flow rate calculation unit sets the target discharge flow rate as
When the target load torque is smaller than the predetermined reference load torque, the first target discharge flow rate is calculated so that the load torque becomes the target load torque.
When the target load torque is greater than or equal to the predetermined reference load torque and the temperature of the hydraulic oil is equal to or higher than the predetermined reference temperature, the hydraulic oil detected by the hydraulic pressure detection device is used. The second target discharge flow rate is calculated so that the load torque becomes the predetermined reference load torque according to the pressure of.
When the target load torque is greater than or equal to the predetermined reference load torque and the temperature of the hydraulic oil is lower than the predetermined reference temperature, the target load torque and the load torque acquisition device are used. A third target discharge such that the load torque becomes the predetermined reference load torque based on the proportional differentiation leading type PID control using the acquired difference from the load torque and the double integration of the difference. A work machine that calculates the flow rate. The work machine according to claim 1.
The discharge flow rate calculation unit
A PID controller that performs calculations by the proportional differential preceding type PID control, and
A double integrator that performs the double integral and
Includes a double integral gain acquisition unit that acquires a double integral gain that is multiplied by the double integral value obtained by performing the double integral.
The double integral gain acquisition unit is a work machine that acquires the double integral gain according to the pressure of the hydraulic oil detected by the hydraulic detection device. The work machine according to claim 1 or 2.
The discharge flow rate calculation unit further
A work machine including a control gain calculation unit that calculates a control gain used for the proportional differential preceding type PID control according to the hydraulic pressure of the hydraulic oil detected by the hydraulic pressure detecting device. The work machine according to any one of claims 1 to 3.
The discharge flow rate calculation unit further
A work machine including a calculation result reset unit that resets the result of the double integral when calculating either the first target discharge flow rate or the second target discharge flow rate. The work machine according to any one of claims 1 to 4.
The control device further
A discharge flow rate estimation unit that estimates the discharge flow rate of the hydraulic pump according to the temperature of the hydraulic oil detected by the temperature detection device is included.
The load torque acquisition device acquires the load torque of the hydraulic pump based on the discharge flow rate of the hydraulic pump estimated by the discharge flow rate estimation unit and the pressure of the hydraulic oil detected by the hydraulic detection device. , Work machine.

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