Patent Application
20240360649
This application claims foreign priority of JP2023-074705 filed Apr. 28, 2023, the disclosure of which is hereby incorporated by reference in its entirety.
The present invention relates to a control method of a work machine, a program, a control system, and a work machine.
This application claims foreign priority of JP2023-074705 filed Apr. 28, 2023, the disclosure of which is hereby incorporated by reference in its entirety.
In harsh work environment such as extreme heat, exposure to high temperature for a long time may cause negative effects on equipment mounted on a work machine. On the other hand, for example, Patent Document 1 discloses a work machine that suppresses a temperature rise of working oil to be supplied to a hydraulic actuator. The work machine reduces the amount of the working oil supplied by decreasing an inclination angle of a hydraulic pump in response to the temperature rise of the working oil. Moreover, the work machine alleviates deceleration control of the hydraulic actuator to reduce flow resistance of the working oil, thereby suppressing heat generation of the working oil. Accordingly, hydraulic equipment including the hydraulic actuator is prevented from being damaged.
In recent years, there have been work machines each including a particulate collecting filter that collects particulates contained in exhaust gas discharged from an engine so as to purify the exhaust gas. The dust collecting filter is regenerated by burning the collected particulates by a periodic temperature rise of the exhaust gas. When the dust collecting filter is regenerated during work such as excavation, a temperature rise inside an engine room may cause negative effects on electric equipment mounted inside the work machine. However, Patent Document 1 does not recite prevention of the temperature rise caused by the regeneration of the dust collecting filter during work and the negative effects on the electric equipment due to the temperature rise.
In view of the above-described circumstances, it is an object of the present invention to suppress an excessive temperature rise inside an engine room.
In order to achieve the above-described object, in a control method of a work machine according to one mode of the present invention, a rotation number of a fan that takes outside air into an engine room accommodating an engine varies with a rotation number of the engine. The control method includes: executing first control of regenerating a collecting filter unit that collects particulates contained in exhaust gas of the engine by a temperature rise of the exhaust gas; when the work machine is changed from a steady state to a specific state, executing second control of decreasing an amount of working oil discharged from a hydraulic pump by driving of the engine; and, when the first control and the second control are concurrently executed, executing third control of increasing the rotation number of the engine.
Moreover, in order to achieve the above-described object, a program according to one mode of the present invention causes a computer to execute a control method of a work machine in which a rotation number of a fan that takes outside air into an engine room accommodating an engine varies with a rotation number of the engine. The program causes the computer to function as a means for: executing first control of regenerating a collecting filter unit that collects particulates contained in exhaust gas of the engine by a temperature rise of the exhaust gas; when the work machine is changed from a steady state to a specific state, executing second control of decreasing an amount of working oil discharged from a hydraulic pump by driving of the engine; and, when the first control and the second control are concurrently executed, executing third control of increasing the rotation number of the engine.
Moreover, in order to achieve the above-described object, a control system of a work machine according to one mode of the present invention includes: an engine; a fan; a collecting filter unit; a hydraulic pump; and a control unit. The engine is accommodated in an engine room. A rotation number of the fan varies with a rotation number of the engine, and the fan takes outside air into the engine room. The collecting filter unit collects particulates contained in exhaust gas of the engine. The hydraulic pump discharges working oil by driving of the engine. The control unit controls the engine and a regulator. The control unit executes first control of regenerating the collecting filter unit by a temperature rise of the exhaust gas, when the work machine is changed from a steady state to a specific state, executes second control of decreasing an amount of the working oil discharged, and, when the first control and the second control are concurrently executed, executes third control of increasing the rotation number of the engine.
Moreover, in order to achieve the above-described object, a work machine according to one mode of the present invention is configured to include the above-described control system.
Additional features and advantages of the present invention will become more apparent from the following embodiment.
According to the present invention, an excessive temperature rise inside an engine room can be suppressed.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic structure of a hydraulic excavator 1 as an example of a work machine will be described with reference to
The lower traveling body 2 is driven by power from an engine 32 to cause the hydraulic excavator 1 to travel. The lower traveling body 2 includes a pair of right and left crawlers 21, 21 and a pair of right and left traveling motors 22, 22. The right crawler 21 and the right traveling motor 22 are not illustrated in
The upper slewing body 3 is configured to be slewable relative to the lower traveling body 2 via a slewing bearing (not illustrated). In the upper slewing body 3, an operation unit 31, the engine 32, a slewing base 33, a slewing motor 34, and the like are arranged. The upper slewing body 3 slews by driving force of the slewing motor 34, which is a hydraulic motor, via the slewing bearing. Moreover, a plurality of hydraulic pumps to be driven by the engine 32 are arranged in the upper slewing body 3. The hydraulic pumps supply working oil to the traveling motors 22, 22, the slewing motor 34, and a boom cylinder 41a, an arm cylinder 42a, and a bucket cylinder 43a, which will be described below, and the like. The traveling motor 22 can switch a rotation number per unit time in response to the amount of the working oil supplied. Hereinafter, the rotation number per unit time will be simply referred to as the “rotation number” without limiting to the traveling motor 22.
An operation seat 311 is arranged in the operation unit 31. A pair of work operation levers 312, 312 is arranged on the right and left of the operation seat 311. A pair of traveling levers 313, 313 is arranged in front of the operation seat 311. An operator sits on the operation seat 311 and operates the work operation levers 312, 312, the traveling levers 313, 313, and the like to control the engine 32, hydraulic motors, hydraulic actuators, and the like, so that traveling, slewing, work, and the like can be performed.
Moreover, an operation panel 314 is arranged in front of the operation seat 311. The operation panel 314 has a display unit 3141 and an operation button including an engine accelerator dial 3142. However, the present embodiment is not limited to this example, and the engine accelerator dial 3142 may be arranged on the right or left of the operation seat 311. The display unit 3141 displays an image for notifying the operator of the state of the hydraulic excavator 1 and the like. The engine accelerator dial 3142 is a rotation number setting unit for the operator to set a target rotation number per unit time of the engine 32. Hereinafter, the target rotation number per unit time will be simply referred to as the “target rotation number”.
The engine 32 is accommodated in an engine room 30. A fan 321 (refer to
The work implement 4 is driven by power from the engine 32 to perform excavation work of soil and the like. The work implement 4 includes a boom 41, an arm 42, and a bucket 43, and can perform the excavation work by independently driving the boom 41, the arm 42, and the bucket 43.
A proximal end part of the boom 41 is supported by a front part of the upper slewing body 3, and the boom 41 is swung in the up-down direction by the boom cylinder 41a which can extendably move.
A proximal end part of the arm 42 is supported by a distal end part of the boom 41, and the arm 42 is swung in the up-down direction by the arm cylinder 42a which can extendably move.
A proximal end part of the bucket 43 is supported by a distal end part of the arm 42, and the bucket 43 is swung in the front-rear direction by the bucket cylinder 43a which can extendably move.
The boom cylinder 41a, the arm cylinder 42a, and the bucket cylinder 43a correspond to hydraulic actuators that drive the work implement 4.
The bucket 43 is a container-shaped member that is attached to the distal end of the work implement 4 and includes claws for performing the excavation work. The bucket 43 is swingably attached via a pin 44 attached to the distal end of the arm 42. Furthermore, the bucket 43 is connected to the bucket cylinder 43a via a link mechanism 45.
Next, a control system 6 included in the hydraulic excavator 1 will be described with reference to
The variable capacity pump 61 is a hydraulic pump that discharges the working oil by the driving of the engine 32, and supplies the working oil to the hydraulic actuator 64. The hydraulic actuator 64 includes the boom cylinder 41a, the arm cylinder 42a, the bucket cylinder 43a, the traveling motor 22, the slewing motor 34, and the like.
An inclination angle of the variable capacity pump 61 is changed by the pump regulator 611 to be driven by the solenoid 62. The pump regulator 611 changes the amount of the working oil discharged in the variable capacity pump 61.
Moreover, a temperature sensor 612 is arranged in the variable capacity pump 61. The temperature sensor 612 detects a temperature of the working oil discharged from the variable capacity pump 61, and transmits the detection result to the integrated ECU 69.
The control valve 63 is arranged between the variable capacity pump 61 and the hydraulic actuator 64, and controls a flow of the working oil to be supplied from the variable capacity pump 61 to the hydraulic actuator 64. The control valve 63 includes a plurality of direction switching valves (not illustrated). The direction switching valves are pilot direction switching valves capable of switching the direction and capacity of the working oil to be pressure-fed from the variable capacity pump 61. For example, the direction switching valves can be switched to a plurality of positions, and are switched, on the basis of a received switching signal, from a neutral position to a position indicated by the switching signal. The respective positions are connected to components included in the hydraulic actuator 64 (that is, the boom cylinder 41a, the arm cylinder 42a, the bucket cylinder 43a, the traveling motor 22, the slewing motor 34, and the like). The working oil is supplied to the components of the hydraulic actuator 64, which are connected to the switched positions.
The radiator 65 cools cooling water of the engine 32. A temperature sensor 651 is arranged in the radiator 65. The temperature sensor 651 detects a temperature of the cooling water sent from the engine 32 to the radiator 65, and transmits the detection result to the integrated ECU 69.
The storage unit 66 is a non-transitory storage medium that retains memory even when electric power supply is stopped. The storage unit 66 stores information, programs, and the like used in the engine ECU 67, the integrated ECU 69, and the like.
The engine ECU 67 can communicate with the integrated ECU 69, receives operation input of the operation unit 31, an instruction signal of the integrated ECU 69, a detection result of a differential pressure sensor 681 of the DPF 68, and the like, and instructs driving of the engine 32, regeneration of the DPF 68, and the like. In the present embodiment, the engine ECU 67 is a control unit different from the integrated ECU 69. However, the present embodiment is not limited to this example, and the engine ECU 67 may be the same control unit as the integrated ECU 69.
The DPF 68 is a collecting filter unit that collects particulates and the like contained in exhaust gas of the engine 32. For example, the DPF 68 has an oxidation catalytic filter member and a collecting filter member, and discharges the exhaust gas through the oxidation catalytic filter member and the collecting filter member. The oxidation catalytic filter member decomposes harmful components in the exhaust gas to produce, for example, NO2 from NOx. Moreover, H2O, CO2 and the like are produced from HC and CO in the exhaust gas. The collecting filter member collects particulates such as particulate matter (PM) contained in the exhaust gas. The collected particulates are removed by, for example, executing the regeneration of the DPF 68 at a predetermined timing. In this regeneration processing, a temperature of the exhaust gas is increased by an after-injection of the engine 32 or the like, so that the particulates are burned by NO2 produced by the oxidation catalytic filter member and oxygen in the exhaust gas. Accordingly, clogging of the collecting filter member is prevented.
The differential pressure sensor 681 is arranged in the DPF 68. The differential pressure sensor 681 detects a pressure difference AP between an inlet and an outlet of the collecting filter member, and transmits the detection result to the engine ECU 67. For example, when the pressure difference AP detected by the differential pressure sensor 681 is equal to or more than a threshold value APs, the engine ECU 67 executes the regeneration of the DPF 68.
The integrated ECU 69 is a control unit that controls respective units configuring the control system 6. The integrated ECU 69 directly or indirectly receives the operation input of the operation unit 31 and the detection results of the temperature sensors 301, 612, and 651, and controls the respective units configuring the control system 6 independently or together with the engine ECU 67. For example, the integrated ECU 69 transmits an instruction to the engine ECU 67 on the basis of a setting of the engine accelerator dial 3142 to control the engine 32, so that the rotation number of the engine 32 approaches the target rotation number. Moreover, the integrated ECU 69 controls the amount of the working oil discharged in the variable capacity pump 61 by control of the solenoid 62. Accordingly, a discharge pressure of the working oil is changed, that is, output of the variable capacity pump 61 is changed.
The determination unit 691 determines whether detection temperatures of the temperature sensors 301, 612, and 651 are equal to or more than respective temperature threshold values.
In the hydraulic excavator 1 in a steady state, the steady control unit 692 drives the engine 32 at a rotation number set by the engine accelerator dial 3142 with a rated rotation number Nr of the engine 32 as an upper limit of the actual rotation number. In the present embodiment, the steady state is a state in which a detection temperature T of the temperature sensor 651 for the cooling water is less than a temperature threshold value Ts. However, the present embodiment is not limited to this example, and the steady state may be a state in which at least one of the detection temperatures of the temperature sensor 301 in the engine room 30, the temperature sensor 612 for the working oil, and the temperature sensor 651 for the cooling water of the engine 32 is less than each temperature threshold value.
The first control unit 693 executes first control. The first control regenerates the DPF 68 by a temperature rise of the exhaust gas of the engine 32. For example, when the pressure difference AP detected by the differential pressure sensor 681 exceeds the threshold value APs, the first control unit 693 executes the above-described first control (i.e., the regeneration processing of the DPF 68). The first control is executed in a state in which the hydraulic excavator 1 can perform work. Thus, the regeneration processing of the DPF 68 can be performed while the work by the hydraulic excavator 1 is continued.
The second control unit 694 executes second control. When the hydraulic excavator 1 is changed from the steady state to a specific state, the second control decreases the amount of the working oil discharged from the variable capacity pump 61 by the driving of the engine 32. That is, in the second control, the amount of the working oil discharged with respect to the rotation number N of the engine 32 in the specific state is set to be lower than the amount of the working oil discharged with respect to the rotation number N of the engine 32 in the steady state.
The specific state includes a state in which the temperature in the engine room 30 is equal to or more than a temperature threshold value higher than the temperature in the steady state. For example, in the present embodiment, the specific state is a state in which the detection temperature T of the temperature sensor 651 for the cooling water is equal to or more than the temperature threshold value Ts. However, the present embodiment is not limited to this example, and the specific state may be a state in which the detection temperature of the temperature sensor 301 in the engine room 30 is equal to or more than the temperature threshold value, or a state in which the detection temperature of the temperature sensor 612 for the working oil of the variable capacity pump 61 is equal to or more than the temperature threshold value. That is, the specific state may be a state in which at least one of the detection temperatures of the temperature sensor 301 in the engine room 30, the temperature sensor 612 for the working oil, and the temperature sensor 651 for the cooling water of the engine 32 is equal to or more than each temperature threshold value. A temperature rise in the engine room 30 can be detected by the detection temperature of any of the temperature sensors 301, 612, and 651. Thus, during the temperature rise in the engine room 30, output R of the variable capacity pump 61 is decreased to reduce load applied to the engine 32, so that a further temperature rise in the engine room 30 can be prevented.
As illustrated in
In contrast, in a case in which the detection temperature T of the cooling water tends to fall, the usable output upper limit of the variable capacity pump 61 is set to a predetermined value until the detection temperature T becomes less than the temperature threshold value Ts. When the detection temperature T becomes less than the temperature threshold value Ts, the usable output upper limit of the variable capacity pump 61 gradually rises up to the maximum (that is, 100%). Accordingly, since a working speed of the hydraulic excavator 1 gradually returns (that is, rises), a collision accident, a pinch accident, or the like in the hydraulic excavator 1 (particularly, the work implement 4) can be prevented.
Therefore, by performing control in the second control as illustrated in
Moreover,
As illustrated in
However, the output R obtained at the same rotation number N varies depending on the detection temperature T of the cooling water (that is, the temperature of the engine 32 and the inside of the engine room 30) (refer to C1 to C6 in
For example, in a case in which the detection temperature T of the cooling water tends to rise, when the detection temperature T is less than the temperature threshold value Ts, the output R with respect to the rotation number N changes like L1. When the detection temperature T becomes equal to or more than the temperature threshold value Ts, the output R with respect to the rotation number N is sharply decreased and changes like L4. That is, the output R of the variable capacity pump 61 is decreased. Accordingly, overheating of the hydraulic excavator 1 during a high-load operation and engine stall (unintended stop of the engine 32) caused by the overheating can be prevented.
In contrast, in a case in which the detection temperature T of the cooling water tends to fall, when the detection temperature T becomes less than the temperature threshold value Ts, the output R with respect to the rotation number N changes in a higher range in accordance with the decrease in the detection temperature T. That is, higher output R can be obtained for the same rotation number N. Accordingly, since the workability of the hydraulic excavator 1 is gradually recovered, the hydraulic excavator 1 can be used safely.
Therefore, by performing control in the second control as illustrated in
Next, the third control unit 695 executes third control. When the first control by the first control unit 693 and the second control by the second control unit 694 are concurrently executed, the third control increases the rotation number N of the engine 32. When the first control is ended, the third control unit 695 stops the third control.
When the regeneration processing of the DPF 68 is performed under the above-described specific state, the third control unit 695 decreases the output R of the variable capacity pump 61 and increases the rotation number N of the engine 32 up to a rotation number Nm exceeding the rated rotation number Nr. For example, as illustrated in
Then, the third control unit 695 increases the rotation number N to the value Nm close to the maximum rotation number, at which the engine 32 can be driven, regardless of the target rotation number set by the engine accelerator dial 3142. At this time, since the load of the engine 32 is decreased due to the decrease in the output R, the engine 32 does not generate much heat. Moreover, by increasing the rotation number N of the engine 32 to exceed the rated rotation number Nr, the rotation number of the fan 321 is increased to take a larger amount of outside air into the engine room 30, and the engine 32 and the inside of the engine room 30 can be cooled. That is, the cooling capacity of the engine 32 and the inside of the engine room 30 by the fan 321 is improved.
Therefore, even in the regeneration processing of the DPF 68 in which the inside of the engine room 30 becomes a severer high-temperature environment, a heat balance between the temperature rise of the engine 32 and the inside of the engine room 30 and the temperature fall due to the cooling by the fan 321 can be achieved, and the work of the hydraulic excavator 1 can be continued. Moreover, in the third control, the temperature in the engine room 30 of the hydraulic excavator 1 is not excessively increased, and thus, the equipment arranged in the engine room 30 can be sufficiently protected from heat.
Next, the fourth control unit 696 executes fourth control. In the fourth control, when the target rotation number of the engine 32 is set to be small by the engine accelerator dial 3142 in the third control, the amount of the working oil discharged in the variable capacity pump 61 is further decreased while the rotation number of the engine 32 is kept increased. Thus, an operation speed of the hydraulic actuator 64 can be reduced in accordance with the setting of the engine accelerator dial 3142 due to the decrease in the amount of the working oil discharged (that is, the output R) in the variable capacity pump 61 even while the rotation number of the engine 32 is kept increased. Therefore, the working speed of the hydraulic excavator 1 can be freely changed by the operator's intention.
Moreover, even during the third control, the rotation number N of the engine 32 remains high by the use of the engine accelerator dial 3142, but the operation speed of the hydraulic actuator 64 can be changed by decreasing the amount of the working oil discharged in the variable capacity pump 61. Thus, as in the case of the steady state, the operator can control the operation of the hydraulic actuator 64 by the use of the engine accelerator dial 3142. Therefore, the operability of the operator can be prevented from being impaired.
As illustrated in
Next, the fifth control unit 697 executes fifth control. In the fifth control, when the target rotation number set by the engine accelerator dial 3142 is set to be lower than a threshold rotation number, the fourth control is stopped, and the engine 32 is controlled on the basis of the target rotation number. For example, when the target rotation number is set to be lower than the threshold rotation number, the rotation number of the engine 32 is controlled by a relationship of the output R with respect to the rotation number N in accordance with the detection temperature of the temperature sensor 651 (refer to L2, L3, and L4 in
Next, an example of a control method of the hydraulic excavator 1 in which the rotation number of the fan 321 that takes outside air into the engine room 30 accommodating the engine 32 varies with the rotation number of the engine 32 will be described.
First, whether the detection temperature T of the temperature sensor 651 is equal to or more than the temperature threshold value Ts is determined (step S1). When T is less than Ts (NO in step S1), whether the pressure difference AP detected by the differential pressure sensor 681 is equal to or more than the threshold value APs is determined (step S2). When the pressure difference AP is less than the threshold value APs (NO in step S2), the processing returns to step S1. When the pressure difference AP is equal to or more than the threshold value APs (YES in step S2), the regeneration processing of the DPF 68 is executed by the first control (step S3), and the processing returns to step S1.
Moreover, when T is equal to or more than Ts (YES in step S1), the inside of the engine room 30 is determined to be changed from the steady state to the specific state. Then, whether the pressure difference AP detected by the differential pressure sensor 681 is equal to or more than the threshold value APs is determined (step S4).
When the pressure difference AP is less than the threshold value APs (NO in step S4), the amount of the working oil discharged (that is, the output R) in the variable capacity pump 61 is decreased by the second control (step S5). Then, whether the detection temperature T of the temperature sensor 651 is equal to or more than the temperature threshold value Ts is determined (step S6). When T is less than Ts (NO in step S6), the amount of the working oil discharged (that is, the output R) in the variable capacity pump 61 gradually returns in accordance with the detection temperature T (refer to
Next, when the pressure difference AP is equal to or more than the threshold value APs (YES in step S4), the regeneration processing of the DPF 68 by the first control and the decrease in the amount of the working oil discharged (that is, the output R) in the variable capacity pump 61 in the specific state by the second control are concurrently executed (step S9), and the rotation number N of the engine 32 is increased to equal to or more than the rated rotation number Nr (refer to
When the target rotation number is set to be small (YES in step S11), the amount of the working oil discharged (that is, the output R) is further decreased while the rotation number N of the engine 32 is kept increased by the fourth control (step S12). Then, whether the set target rotation number is lower than the threshold rotation number is determined (step S13). When the set target rotation number is not lower than the threshold rotation number (NO is step S13), the processing returns to step S11.
When the set target rotation number is lower than the threshold rotation number (YES is step S13), the fourth control is stopped, and the engine 32 is controlled on the basis of the target rotation number by the fifth control (step S14). That is, the engine 32 is driven and controlled such that the rotation number N thereof becomes the target rotation number. Then, the processing returns to step S1.
In steps S11 to S13, when either the ending of the first control (that is, the ending of the regeneration processing of the DPF 68) or the ending of the second control (for example, a change from the specific state to the steady state) occurs, the third control, the fourth control, and the fifth control are immediately stopped, and the processing returns to step S1.
The embodiment of the present invention has been described above. It should be understood by those skilled in the art that the above-described embodiment is merely an example, and various modifications can be made to the combination of the respective components and the respective pieces of processing, which are within the scope of the present invention.
Hereinafter, the above-described embodiment will be collectively described.
For example, a control method of a work machine 1 disclosed herein is
The control method of a work machine 1 of the above-described first configuration
Moreover, the control method of a work machine 1 of the above-described first or second configuration
Moreover, the control method of a work machine 1 of any one of the above-described first to third configurations
Moreover, the control method of a work machine 1 of the above-described fourth configuration
Moreover, the control method of a work machine 1 of any one of the above-described first to fifth configurations
Moreover, the control method of a work machine 1 of any one of the above-described first to sixth configurations
Moreover, a program disclosed herein is
Moreover, a control system 6 of a work machine 1 disclosed herein includes:
Moreover, a work machine 1 disclosed herein is configured to include the control system of a work machine 1 of the ninth configuration (tenth configuration).
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-074705 | Apr 2023 | JP | national |
