JP2021055542A - Working machine - Google Patents

Abstract

To provide a working machine that removes particulate matter (PM, mainly soluble organic fraction (SOF)) before the PM adheres excessively to an oxidation catalyst.SOLUTION: A working machine includes: an engine 41; an oxidation catalyst 44 that promotes oxidation of components contained in exhaust gas of the engine 41; a hydraulic pump 51 as a loading device driven by the engine 41; a controller 80 that controls operation of a machine body according to operation of an operation device, and outputs a target engine speed to an engine control unit 42; and a second pressure detection device 62 as an operation state detection device that detects an operation state of the operation device. The controller 80 determines, based on a detection result P from the operation state detection device 62, whether a time period during which a non-operation state of the machine body continues reaches a first time period S1, and if the time period is determined to have reached the first time period S1, performs a load increase control to increase the load of the hydraulic pump 51 or the target engine speed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a work machine, and more particularly to a work machine provided with an aftertreatment device for purifying the exhaust gas of an engine.

Work machines such as hydraulic excavators, cranes, and wheel loaders equipped with diesel engines are equipped with aftertreatment devices that purify exhaust gas in order to comply with engine exhaust gas regulations. The aftertreatment device has at least an oxidation catalyst, and if necessary, includes a collection filter such as a DPF (Diesel Particulate Filter) and a NOx purification device. The collection filter collects particulate matter (PM: Particulate Matter), and requires a regeneration process for burning and removing the PM deposited on the filter. The regeneration process of the collection filter is generally performed by burning the fuel-derived HC supplied into the exhaust gas with an oxidation catalyst to raise the exhaust gas to the filter regeneration temperature and burning the PM deposited on the collection filter. Will be done.

By the way, in the work machine, the operation in the low load and low rotation range may be continued. In the operation in the low load and low rotation range, the amount of PM generated is small and the amount of PM (mainly soot) deposited on the collection filter is also small as compared with the operation in the high load and high rotation range. However, in operation in the low load and low rotation range, the temperature of the exhaust gas becomes low, so that the soluble organic component (SOF: Soluble Organic Fraction) of PM may adhere to the oxidation catalyst. Therefore, if the operation in the low load and low rotation range is continued, there is a concern that the SOF may be excessively adhered to the oxidation catalyst.

As a measure for preventing clogging of the oxidation catalyst due to the adhesion of PM, for example, the technique described in Patent Document 1 has been proposed. The technique described in Patent Document 1 is when the exhaust gas temperature is raised to the catalytically active temperature of the oxidation catalyst at the time of regeneration of the particulate filter (DPF), and then HC is supplied to the exhaust system to burn and remove the PM accumulated in the DPF. When the internal combustion engine is constantly operated at low load and low rotation, the exhaust gas temperature at the inlet of the oxidation catalyst becomes the PM combustion temperature (higher than the catalytically active temperature) once every several times of the DPF regeneration. The oxidation catalyst PM removal operation is performed to remove the PM (mainly SOF) adhering to the oxidation catalyst by raising the exhaust gas temperature as described above.

JP-A-2017-0755552

In the technique described in Patent Document 1, the DPF is regenerated every time the operating time of the internal combustion engine reaches a preset time. However, as described above, in the operation in the low load and low rotation range, the amount of PM generated is smaller than that in the operation in the high load and high rotation range. The amount of soot) is also reduced. Therefore, when the operation in the low load and low rotation range is continued, if the DPF regeneration is performed every set period as in the technique described in Patent Document 1, the DPF The number of playbacks will increase.

Therefore, as a method of reducing the number of times of regeneration of the DPF, it is conceivable to set the regeneration time of the DPF according to the amount of PM accumulated in the collection filter. When the DPF regeneration time is set in this way, it is expected that the DPF regeneration interval will become very long if the operation in the low load and low rotation range is continued. However, on the other hand, in the operation in the low load and low rotation range, the SOF adheres to the oxidation catalyst. Therefore, when the operation of removing the PM (mainly SOF) adhering to the oxidation catalyst is performed once every several times of the DPF regeneration as in the technique described in Patent Document 1, the operation in the low load and low rotation range is performed. If it is continued, there is a concern that SOF may be excessively attached to the oxidation catalyst due to the lengthening of the DPF regeneration interval. If the DPF that raises the exhaust gas temperature is regenerated after the excessive adhesion of the SOF, it is possible that the DPF will be damaged by the influence of the excessively attached SOF.

The present invention has been made on the basis of the above, and an object of the present invention is to provide a working machine for removing PM before PM (mainly SOF) is excessively attached to an oxidation catalyst.

The present application includes a plurality of means for solving the above problems. For example, an oxidation catalyst arranged in an engine and an exhaust gas path of the engine and promoting oxidation of components contained in the exhaust gas of the engine. The load device driven by the engine, the engine control unit that controls the engine based on the target engine speed, and the operation of the machine body according to the operation of the operation device, and the engine control unit A work machine equipped with a controller for outputting the target engine speed is provided with an operation state detection device for detecting the operation state of the operation device, and the controller is the machine body based on a detection result from the operation state detection device. It is determined whether or not the time during which the non-operation state continues has reached the preset first time, and when it is determined that the first time has been reached, the load of the load device or the said It is characterized in that load increase control is performed to increase the target engine speed from that at the time of the determination.

According to the present invention, the load of the load device or the target engine speed is determined after determining the situation in which PM (mainly SOF) is expected to adhere to the oxidation catalyst in which the non-operating state of the aircraft continues for the first time. Since the temperature of the engine exhaust gas is raised by the control of raising the temperature, PM can be removed from the oxidation catalyst before PM is excessively attached to the oxidation catalyst.
Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is a side view which shows the hydraulic excavator to which the 1st Embodiment of the work machine of this invention is applied. It is a block diagram which shows the exhaust gas treatment system and the hydraulic system in 1st Embodiment of the work machine of this invention. It is a flowchart which shows an example of the procedure of the load increase control by the controller which constitutes a part of the 1st Embodiment of the work machine of this invention shown in FIG. It is a block diagram which shows the exhaust gas treatment system and the hydraulic system in the 2nd Embodiment of the work machine of this invention. It is a flowchart which shows an example of the procedure of the load increase control by the controller which constitutes a part of the 2nd Embodiment of the work machine of this invention shown in FIG.

Hereinafter, embodiments of the working machine of the present invention will be described with reference to the drawings. In the present embodiment, a hydraulic excavator will be described as an example of a work machine.

First, the configuration of a hydraulic excavator as a first embodiment of the work machine of the present invention will be described with reference to FIG. FIG. 1 is a side view showing a hydraulic excavator to which the first embodiment of the work machine of the present invention is applied. Here, the direction seen from the operator seated in the driver's seat will be described.

In FIG. 1, the hydraulic excavator 1 as a work machine is mounted on a self-propelled lower traveling body 2, an upper rotating body 3 mounted on the lower traveling body 2 so as to be swivel, and is raised and lowered on the front portion of the upper swivel body 3. It is equipped with a front working machine 4 that is movably provided.

The lower traveling body 2 is provided with crawler-type traveling devices 11 on the left and right sides. The left and right traveling devices 11 are each driven by a traveling hydraulic motor 12 as a hydraulic actuator.

The upper swivel body 3 is swiveled and driven with respect to the lower traveling body 2 by, for example, a swivel hydraulic motor (not shown) as a hydraulic actuator. The upper swivel body 3 has a swivel frame 21 which is a support structure, a driver's cab 22 installed on the front left side on the swivel frame 21, a machine room 23 arranged on the rear side on the swivel frame 21, and swivel. It is configured to include a counter weight 24 attached to the rear end of the frame 21. In the driver's cab 22, an operator such as an operation lever device 64 as an operation device described later, a gate lock lever 65 (both see FIG. 2 described later), an engine control dial (not shown), or the like operates the hydraulic excavator 1. Various devices are arranged. The machine room 23 houses an engine 41 and an aftertreatment device 43 (both of which are described in FIG. 2 below), a hydraulic pump 51 of the hydraulic system 50, and various devices (see FIG. 2 of the following). The counterweight 24 is for balancing the weight with the front working machine 4.

The front work machine 4 is an articulated work device for performing excavation work and the like, and includes, for example, a boom 31, an arm 32, and a bucket 33 as an attachment. The base end of the boom 31 is rotatably connected to the front end of the swivel frame 21 of the upper swivel body 3. A base end portion of the arm 32 is rotatably connected to the tip end portion of the boom 31. A base end portion of the bucket 33 is rotatably connected to the tip end portion of the arm 32. The boom 31, arm 32, and bucket 33 are driven by the boom cylinder 35, arm cylinder 36, and bucket cylinder 37, respectively. The boom cylinder 35, arm cylinder 36, and bucket cylinder 37 are hydraulic actuators that can be expanded and contracted by supplying pressure oil.

Next, the configuration of the exhaust gas treatment system and the hydraulic system according to the first embodiment of the work machine of the present invention will be described with reference to FIG. FIG. 2 is a configuration diagram showing an exhaust gas treatment system and a hydraulic system according to the first embodiment of the work machine of the present invention. In FIG. 2, those having the same reference numerals as those shown in FIG. 1 have the same reference numerals, and thus detailed description thereof will be omitted.

In FIG. 2, the hydraulic excavator 1 includes an engine 41 such as a diesel engine that discharges exhaust gas, an engine control unit 42 that controls the rotation speed and output torque of the engine 41, and a post-treatment that purifies the exhaust gas discharged from the engine 41. It includes a device 43. The hydraulic excavator 1 also includes a hydraulic system 50 that drives the lower traveling body 2, the upper turning body 3, and the front working machine 4 (both of which see FIG. 1), which are the bodies of the hydraulic excavator 1, by using the engine 41 as a prime mover, and an operator. It includes a controller 80 that controls the operation of the machine body via the hydraulic system 50 according to the operation.

An exhaust pipe 46 is connected to the engine 41 as an exhaust gas path that guides the exhaust gas of the engine 41 to the outside air. Further, the engine 41 is provided with an engine rotation speed detection device 47 that detects the actual rotation speed of the engine 41. The engine rotation speed detection device 47 is composed of, for example, an angular velocity sensor, and outputs a detection signal of the actual rotation speed of the engine 41 to the engine control unit 42.

The engine control unit 42 controls the engine 41 based on the target engine speed. Specifically, the engine control unit 42 performs a predetermined calculation process based on the command signal of the target engine speed from the controller 80 and the detection signal of the actual speed of the engine 41 from the engine speed detection device 47, and calculates. By outputting a control command generated based on the result, the fuel injection amount injected into each cylinder of the engine 41 is controlled. As a result, the engine 41 is controlled so that the actual engine speed matches the target engine speed.

The aftertreatment device 43 is arranged in the middle portion of the exhaust pipe 46. The aftertreatment device 43 is composed of, for example, an oxidation catalyst 44 arranged on the upstream side (front stage) of the exhaust gas path and a collection filter 45 arranged on the downstream side (rear stage) of the exhaust gas path from the oxidation catalyst 44. ing.

The oxidation catalyst 44 promotes the oxidation of the components contained in the exhaust gas of the engine 41. For example, the catalytically active component is supported on a porous carrier of an inorganic compound. The components to be oxidized in the exhaust gas are mainly hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). By the catalytic action of the oxidation catalyst 44, HC is oxidized to H2O and CO2, and CO is oxidized to CO2. Of the NOx, NO is oxidized to NO2.

The collection filter 45 collects PM contained in the exhaust gas of the engine 41. The collection filter 45 requires a regeneration process for periodically burning and removing PM (mainly soot) deposited on the collection filter 45. The regeneration process of the collection filter 45 forcibly raises the exhaust gas temperature to the renewable temperature of the collection filter 45 when a predetermined condition is satisfied, for example, when the estimated accumulated amount of PM exceeds the predetermined amount. It is done by letting. This regeneration process is executed by the engine control unit 42 controlling the engine 41.

The aftertreatment device 43 is provided with an exhaust gas temperature detection device 48 that detects the temperature of the exhaust gas flowing through the aftertreatment device 43. The exhaust gas temperature detecting device 48 is arranged, for example, on the inlet side of the oxidation catalyst 44, and detects the exhaust gas temperature immediately before being introduced into the oxidation catalyst 44. The exhaust gas temperature detection device 48 outputs a detection signal of the exhaust gas temperature to the engine control unit 42.

The hydraulic system 50 includes a hydraulic pump 51 and a pilot pump 52 as load devices driven by the engine 41, a hydraulic actuator group 53 driven by pressure oil discharged from the hydraulic pump 51, and a hydraulic actuator group 53 from the hydraulic pump 51. It is provided with a control valve device 54 that controls the flow (direction and flow rate) of the hydraulic oil supplied to the pump.

The hydraulic pump 51 is, for example, a variable displacement pump, and has a variable mechanism (for example, a swash plate or an oblique shaft) for a push-out volume (discharge flow rate per rotation speed) and a tilt (for example, tilt) of the variable mechanism. It is provided with a regulator 51a that adjusts the corner) to control the push-out volume of the hydraulic pump 51. The regulator 51a adjusts the tilt of the variable mechanism by introducing the pilot pressure from the pilot pump 52. For example, the pilot pressure from the pilot pump 52 is introduced into the regulator 51a via the first solenoid valve 55. The first solenoid valve 55 is electrically connected to the controller 80, and the throttle amount of the first solenoid valve 55 is controlled by a control command from the controller 80.

A first pressure detecting device 61 for detecting the discharge pressure of the hydraulic pump 51 is provided in the discharge pipe line connected to the hydraulic pump 51. The first pressure detection device 61 outputs a detection signal of the discharge pressure of the hydraulic pump 51 to the controller 80.

The hydraulic actuator group 53 is composed of a plurality of hydraulic actuators such as the left and right traveling hydraulic motors 12, the boom cylinder 35, the arm cylinder 36, the bucket cylinder 37, and the swivel hydraulic motor (not shown) shown in FIG. The airframe is operated by driving at least one of the hydraulic actuator group 53.

The control valve device 54 is a collection of a plurality of control valves corresponding to each of the plurality of hydraulic actuators 12, 35, 36, and 37 constituting the hydraulic actuator group 53. The plurality of control valves are, for example, open center type and hydraulic pilot operated valves.

The upstream side of the center bypass line 57 is connected to the discharge side of the hydraulic pump 51, and the downstream side is connected to the hydraulic oil tank 58. A variable throttle valve 59 is provided on the downstream side of the control valve device 54 in the center bypass line 57. The variable throttle valve 59 is configured so that the opening area is variable between the fully open position X and the fully closed position Y. The variable throttle valve 59 is, for example, a pilot hydraulically operated valve, and the pilot pressure from the pilot pump 52 is introduced via the second solenoid valve 56. The second solenoid valve 56 is electrically connected to the controller 80, and the throttle amount of the second solenoid valve 56 is adjusted according to a control command from the controller 80.

The control valve device 54 is switched and operated by the operation pilot pressure from the operation lever device 64. The operation lever device 64 functions as an operation device that instructs the operation of the airframe in response to the operation of the operator (only one is shown as a representative). The operation device can be configured to include, for example, an operation pedal device in addition to the operation lever device 64. The operation lever device 64 uses the pilot pressure from the pilot pump 52 as the primary pressure to generate an operation pilot pressure according to the operator's operation (operation direction and operation amount). When the operator is not operating the operation lever device 64 (for example, when the operation lever device 64 is in the neutral position), the operation pilot pressure generated by the operation lever device 64 is less than a predetermined value.

The pilot line from the operating lever device 64 to the control valve device 54 is provided with a second pressure detecting device 62 that detects the operating pilot pressure generated by the operating lever device 64. The second pressure detection device 62 outputs a detection signal of the operation pilot pressure of the operation lever device 64 to the controller 80. In the present embodiment, the second pressure detection device 62 functions as an operation state detection device that detects the operation state of the operation lever device 64 as the operation device. When the pressure value detected by the second pressure detection device 62 is less than the predetermined pressure threshold value Pt, the operation lever device 64 is in the neutral position and the operator is not operating the aircraft via the operation lever device 64. It can be regarded as an operating state.

The hydraulic system 50 includes a gate lock lever 65 that disables the operation of the control valve device 54 by the operation lever device 64, that is, the operator's operation on the airframe by the operation lever device 64. The gate lock lever 65 can be selectively operated at the lock position L that opens the entrance of the driver's seat and the unlock position U that limits the entrance of the driver's seat. When the gate lock lever 65 is operated to the lock position L, the primary pressure from the pilot pump 52 supplied to the operation lever device 64 is cut off, and the hydraulic actuator group 53 (aircraft) is operated via the operation lever device 64. Becomes impossible. On the other hand, when the gate lock lever 65 is operated to the unlock position U, the cutoff of the primary pressure supplied to the operation lever device 64 is released, and the hydraulic actuator group 53 (airframe) is operated via the operation lever device 64. Is possible. That is, the gate lock lever 65 functions as an operating device that indirectly instructs the operation of the airframe via the operating lever device 64 in response to the operator's operation to the lock position L or the unlock position U. The gate lock lever 65 has a position detecting device 66 that detects an operating position (locking position L or unlocking position U). The position detection device 66 outputs a detection signal of the operation position of the gate lock lever 65 to the controller 80.

A notification device 100 is connected to the controller 80. The notification device 100 notifies the operator of predetermined information and alerts, which will be described later, by a notification command from the controller 80. The notification device 100 is arranged in the driver's cab 22 (see FIG. 1), and can be configured by a buzzer that emits a notification sound, a speaker that emits a voice, a monitor that displays the notification content, and the like.

An EC dial (not shown) for instructing the set rotation speed of the engine 41 according to the operation of the operator is connected to the controller 80. The controller 80 calculates the target engine speed according to the instruction signal of the set speed from the EC dial and the operating state of the airframe. The controller 80 transmits (outputs) the target engine speed as a calculation result to the engine control unit 42 via a communication means such as CAN, and is a detection value of the exhaust gas temperature detection device 48 from the engine control unit 42. Receive the exhaust gas temperature.

Further, the controller 80 is electrically connected to the first solenoid valve 55 and the second solenoid valve 56, controls the push-out volume of the hydraulic pump 51 via the first solenoid valve 55, and the second solenoid valve 56. The throttle amount of the variable throttle valve 59 is controlled via the above. The controller 80 of the present embodiment performs a predetermined comparison determination and arithmetic processing based on the detection result from the second pressure detection device 62, and controls the throttle amount of the variable throttle valve 59 and the push-out volume of the hydraulic pump 51. , The load increase control for increasing the load (power) of the hydraulic pump 51 is performed. In the hydraulic excavator 1, the exhaust gas temperature becomes low during operation of the engine 41 in the low load and low rotation range (that is, when the airframe is not operated), so that SOF of PM adheres to the oxidation catalyst 44. Tend to do. If the operation of the engine 41 in the low load and low rotation range is continued, there is a concern that the SOF may excessively adhere to the oxidation catalyst 44. Therefore, it is necessary to remove the SOF before it excessively adheres to the oxidation catalyst 44. Therefore, the controller 80 raises the exhaust gas temperature of the engine 41 by increasing the load (power of the hydraulic pump 51) applied to the engine 41 by the load increase control, and performs a process of removing the SOF from the oxidation catalyst 44.

As a hardware configuration, the controller 80 includes, for example, a storage device 81 including a RAM, a ROM, or the like, and an arithmetic processing device 82 including a CPU or the like including a timer capable of measuring time. The storage device 81 stores in advance programs and various information necessary for the load increase control and other controls. The arithmetic processing unit 82 realizes various functions including the following functions by appropriately reading a program and various information from the storage device 81 and executing processing according to the program.

The controller 80 has, for example, a storage unit 91 as a function of the storage device 81, a non-operation state determination unit 92 as a function executed by the arithmetic processing unit 82, and a load control unit 93 as functions for executing load increase control. And the control end determination unit 94 is provided.

The storage unit 91 stores a predetermined pressure threshold value Pt and a preset first time S1. The pressure threshold value Pt and the first time S1 are used by the non-operating state determination unit 92 for determining the continuation of the non-operating state of the aircraft, which will be described later. The pressure threshold value Pt is the operating pilot pressure of the operating lever device 64 when the aircraft is operated via the operating lever device 64 as the operating device, and the aircraft is not operated via the operating lever device 64. It is a value that can be distinguished from the operating pilot pressure at the time. In the first time S1, PM (mainly SOF) adheres to the oxidation catalyst 44 in view of the fact that PM adheres to the oxidation catalyst 44 when the operation of the engine 41 in the low load and low rotation range is continued. It is the duration of the non-operating state (operation of the engine 41 in the low load and low rotation range) of the aircraft, which is assumed to be a situation.

Further, the storage unit 91 stores a predetermined temperature threshold value Tt, a preset second time S2, and a preset third time S3. The temperature threshold value Tt and the second time S2 are used by the load control unit 93 for determining the completion of the PM removal process described later. The temperature threshold value Tt and the third time S3 are used by the load control unit 93 for determining the inability of the PM removal process described later. The temperature threshold Tt is a temperature at which PM (mainly SOF) adhering to the oxidation catalyst 44 can be removed. The second time S2 is a treatment time required for surely removing PM (mainly SOF) adhering to the oxidation catalyst 44.

The non-operation state determination unit 92 determines whether or not PM (mainly SOF) is expected to adhere to the oxidation catalyst 44. Specifically, the non-operating state determination unit 92 measures the first duration t1 in which the non-operating state of the aircraft continues based on the detection result P of the second pressure detecting device 62 as the operating state detecting device. This is for determining whether or not the measured first duration t1 has reached the first time S1 stored in advance in the storage unit. More specifically, the non-operation state determination unit 92 compares the detection value P from the second pressure detection device 62 with the pressure threshold value Pt stored in advance in the storage unit 91, so that the operation lever device as the operation device It is determined whether or not the operating state of the aircraft via 64 is the non-operating state. When the detection value P of the second pressure detection device 62 is smaller than the pressure threshold value Pt, it is determined that the machine is not in operation because the machine is not operated via the operation lever device 64. On the other hand, when the detection value P of the second pressure detection device 62 is larger than the pressure threshold value Pt, it is determined that the machine is not in a non-operation state because the machine is being operated via the operation lever device 64. .. Further, the non-operation state determination unit 92 measures the first duration t1 in which the detected value P is larger than the pressure threshold Pt, and the measured first duration t1 is the first time S1. Is determined.

When the non-operation state determination unit 92 determines that the airframe is in the non-operation continuation state, the load control unit 93 controls the configuration of the hydraulic system 50 to determine the load (power) of the hydraulic pump 51. The load increase control is performed to increase the load more than the time. Specifically, the load control unit 93 controls the opening area of the variable throttle valve 59 to be narrower than that at the time of the determination by outputting a control command to the second solenoid valve 56. Further, the load control unit 93 can output a control command to the first solenoid valve 55 to control the push-out volume of the hydraulic pump 51 to be larger than that at the time of the determination. It is also possible to control the opening area of the variable throttle valve 59 and the push-out volume of the hydraulic pump 51 at the same time.

The control end determination unit 94 determines the completion of the PM removal process adhering to the oxidation catalyst 44 when the load increase control is started by the load control unit 93. Specifically, by comparing the detected value T (that is, the exhaust gas temperature) from the exhaust gas temperature detecting device 48 with the temperature threshold value Tt stored in advance in the storage unit 91, PM adhering to the oxidation catalyst 44 can be removed. It is determined whether or not the state is in the state. When the detection value T of the exhaust gas temperature detection device 48 is equal to or higher than the temperature threshold value Tt, it is determined that the temperature of the exhaust gas has reached the removable temperature of PM adhering to the oxidation catalyst 44. On the other hand, when the detected value T is less than the temperature threshold value Tt, it is determined that the temperature of the exhaust gas has not reached the temperature at which PM can be removed.

When the detected value T is equal to or higher than the temperature threshold Tt, the control end determination unit 94 measures the second duration t2 in which the detected value T continues at the temperature threshold Tt or higher, and measures the second duration t2. Determines whether or not has reached the second time S2 stored in advance in the storage unit 91. When the second duration t2 reaches the second time S2, the control end unit 94 determines that the removal process of PM adhering to the oxidation catalyst 44 is completed, and determines that the load increase control is terminated.

On the other hand, when the detection value T of the exhaust gas temperature detection device 48 is less than the temperature threshold value Tt, the control end determination unit 94 determines whether or not to forcibly terminate the load increase control. Specifically, a third duration t3 in which the detected value T continues below the temperature threshold value Tt is measured, and the measured third duration t3 is stored in the storage unit 91 in advance for a third time. It is determined whether or not S3 has been reached. When the third duration t3 reaches the third time S3, the load control unit 93 cannot obtain an appropriate rise in the exhaust gas temperature even if the load rise control is executed, and PM removal is impossible. It is determined that the load increase control is forcibly terminated.

Further, when the third duration t3 reaches the third time S3, the control end determination unit 94 cannot reach the second duration S2 even if the load increase control is performed, and the load increases. A notification command for notifying the operator that the control is to be terminated is output to the notification device 100.

Next, an example of the control procedure executed by the controller constituting the first embodiment of the work machine of the present invention will be described with reference to FIGS. 2 and 3. FIG. 3 is a flowchart showing an example of a procedure for load increase control by a controller that constitutes a part of the first embodiment of the work machine of the present invention shown in FIG.

First, in the controller 80 shown in FIG. 2, whether the non-operation state of the airframe continues for the first time S1 based on the detection result P (operation pilot pressure) from the second pressure detection device 62 as the operation state detection device. Whether or not it is determined (step S10 shown in FIG. 3). Specifically, the non-operation state determination unit 92 of the controller 80 determines that the detection value P from the second pressure detection device 62 is equal to or less than the pressure threshold Pt stored in the storage unit 91 (that is, the non-operation state of the aircraft). The continuous first duration t1 is measured, and it is determined whether or not the measured first duration t1 has reached the first time S1 stored in the storage unit 91. If the detected value P is larger than the pressure threshold Pt and the aircraft is in the operating state, or if the first duration t1 is less than the first time S1, that is, if NO, step S10 is repeated again.

On the other hand, if YES in step S10 (that is, P ≦ Pt and t1 ≧ S1), it is assumed that PM (mainly SOF) is attached to the oxidation catalyst 44. Therefore, the controller 80 controls the load increase of the hydraulic system 50 in order to remove the PM adhering to the oxidation catalyst 44 (step S20 shown in FIG. 3). Specifically, the load control unit 93 of the controller 80 performs load increase control to increase the load (power) of the hydraulic pump 51 as compared with the case where it is determined that the non-operating state of the airframe is continuing. For example, the load control unit 93 controls the variable throttle valve 59 via the second solenoid valve 56 so as to throttle the variable throttle valve 59 more than at the time of the determination. As a result, the resistance of the flow of pressure oil in the variable throttle valve 59 increases, and the discharge pressure of the hydraulic pump 51 can be increased. Therefore, the load on the hydraulic pump 51 applied to the engine 41 increases, so that the temperature of the exhaust gas of the engine 41 rises.

Further, the load control unit 93 can also control the hydraulic pump 51 so that the push-out volume of the hydraulic pump 51 is larger than that at the time of the determination via the first solenoid valve 55. As a result, the absorption torque of the hydraulic pump 51 increases, so that the load on the hydraulic pump 51 applied to the engine 41 increases, and the temperature of the exhaust gas of the engine 41 rises.

Further, the load control unit 93 can simultaneously control the opening area of the variable throttle valve 59 and the push-out volume of the hydraulic pump 51. As a result, both the discharge pressure and the absorption torque of the hydraulic pump 51 increase, so that the load on the hydraulic pump 51 applied to the engine 41 further increases, and the temperature of the exhaust gas of the engine 41 further rises.

Next, the controller 80 determines whether or not the PM adhering to the oxidation catalyst 44 has been removed by the load increase control (step S30 shown in FIG. 3). Specifically, the control end determination unit 94 determines the detection value T (exhaust gas temperature) from the exhaust gas temperature detection device 48 by comparing it with the temperature threshold value Tt stored in advance in the storage unit 91. When the detected value T is equal to or higher than the temperature threshold value Tt (YES), it is determined that the PM adhering to the oxidation catalyst 44 can be removed, and the process proceeds to step S40 shown in FIG. On the other hand, when the detected value T is less than the temperature threshold value Tt (NO), it is determined that the PM adhering to the oxidation catalyst 44 is not in a removable state, and the process proceeds to step S60 shown in FIG.

If YES in step S30, the control end determination unit 94 measures the second duration t2 in which the detection value T of the exhaust gas temperature detection device 48 continues at the temperature threshold value Tt or higher, and the measured second duration is measured. It is determined whether or not t2 has reached the second time S2 stored in the storage unit 91 (step step S40 shown in FIG. 3). If the second measurement time t2 is less than the second time S2 (NO), steps S30 and S40 are repeated again. In some cases, the process proceeds to step S60.

On the other hand, in step S40, when the second measurement time t2 reaches the second time S2 (YES), the controller 80 reliably removes PM (mainly SOF) adhering to the oxidation catalyst 44. It is determined that the required time has elapsed, and the load increase control is terminated (step S50 shown in FIG. 3). Specifically, the load control unit 93 controls the opening area of the variable throttle valve 59 to return to the state before the load increase control via the second solenoid valve 56. As a result, the discharge pressure of the hydraulic pump 51 decreases, so that the load on the hydraulic pump 51 applied to the engine 41 decreases, and the temperature of the exhaust gas of the engine 41 decreases. When controlling the push-out volume of the hydraulic pump 51, it may be controlled to return to the state before the load increase control.

If NO in step S30, the controller 80 determines whether or not the PM that has adhered to the oxidation catalyst 44 cannot be removed continues (step S60 shown in FIG. 3). Specifically, the control end determination unit 94 measures the third duration t3 in which the detection value T of the exhaust gas temperature detection device 48 continues below the temperature threshold value Tt, and the measured third duration t3 is It is determined whether or not the third time S3 stored in the storage unit 91 has been reached. If the third measurement time t3 is less than the third time S3 (NO), steps S30 and S60 are repeated again. In some cases, the detected value T becomes equal to or higher than the temperature threshold value Tt, and the process proceeds to step S40. For example, it is conceivable that the low exhaust gas temperature rises with the passage of time in the initial state of the load rise control.

When the third duration t3 reaches the third time S3 in step S60 (yes), the controller 80 determines that the exhaust gas temperature cannot be appropriately raised and PM cannot be removed. A determination is made and a notification command is output to the notification device 100 (step S70 shown in FIG. 3). As a result, the notification device 100 notifies the operator that the PM adhering to the oxidation catalyst 44 cannot be removed, and also notifies the operator that the aircraft is operated and the engine 41 is stopped. To do. After the output of the notification command, the controller 80 forcibly terminates the load increase control without the second duration t2 reaching the second time S2 (step S50 shown in FIG. 3).

As described above, in the first embodiment of the working machine of the present invention, the engine 41 and the oxidation catalyst 44 arranged in the exhaust gas path of the engine 41 and promoting the oxidation of the components contained in the exhaust gas of the engine 41. , A hydraulic pump 51 as a load device driven by the engine 41, an engine control unit 42 that controls the engine 41 based on a target engine rotation speed, and an operation lever device 64 as an operation device. The hydraulic excavator 1 as a work machine provided with a controller 80 that controls the operations of 4 and outputs a target engine rotation speed to the engine control unit 42 detects the operating state of the operating lever device 64 as an operating device. A second pressure detecting device 62 is further provided as an operating state detecting device, and the controller 80 is a period during which the non-operating states of the aircraft 2, 3 and 4 are continued based on the detection result P from the second pressure detecting device 62. (First duration) It is determined whether or not t1 has reached the preset first time S1, and when it is determined that the first time S1 has been reached, the load of the hydraulic pump 51 is applied at the time of the determination. The load increase control is performed to increase the load.

According to this configuration, PM (mainly SOF) is assumed to adhere to the oxidation catalyst 44 in which the non-operating state of the aircraft 2, 3 and 4 continues for the first time S1, and thus the load device is used. Since the temperature of the exhaust gas of the engine 41 is raised by controlling the load of the hydraulic pump 51 to be raised, the PM can be removed from the oxidation catalyst 44 before the PM excessively adheres to the oxidation catalyst 44.

Further, in the present embodiment, the controller 80 determines at least one of the discharge pressure and the push-out volume of the hydraulic pump 51 from the time of the determination (when it is determined that the non-operating states of the aircraft 2, 3 and 4 are continuing). Is also configured to control the load increase by increasing the load. According to this configuration, since the control target in the load increase control of the controller 80 is the configuration of the hydraulic system 50, it is easy to increase the load applied to the engine 41.

Further, in the present embodiment, the hydraulic excavator 1 is further provided with an exhaust gas temperature detecting device 48 which is installed on the upstream side of the oxidation catalyst 44 in the exhaust gas path and detects the temperature of the exhaust gas discharged from the engine 41, and the controller is provided with an exhaust gas temperature detecting device 48. In the load increase control, whether or not the time (second duration) t2 in which the detection temperature T of the exhaust gas temperature detection device 48 continues at the predetermined temperature threshold Tt or more reaches the preset second time S2. When it is determined that the time (second duration) t2 that continues at the predetermined temperature threshold Tt or higher has reached the second time S2, the load increase control is terminated. According to this configuration, the load increase control is terminated after confirming that the temperature at which PM adhering to the oxidation catalyst 44 can be removed continues for a predetermined period, so that PM adhering to the oxidation catalyst 44 can be reliably removed. Can be done.

Further, in the present embodiment, the hydraulic excavator 1 further includes a notification device 100 that notifies the operator based on the notification command of the controller 80 and the like, and the controller 80 is the exhaust gas temperature detection device 48 in the load increase control. It is determined whether or not the time (third duration) t3 in which the detected temperature continues below the predetermined temperature threshold Tt has reached the preset third time S3, and continues below the predetermined temperature threshold Tt. When it is determined that the time (third duration) t3 has reached the third time S3, the load increase control is terminated and the time (second duration) is continued at a predetermined temperature threshold value Tt or higher. The duration) t2 is configured to output a notification command to the notification device 100 to notify the operator that the load increase control ends without reaching the second time S2. According to this configuration, it is possible to alert the operator to a situation in which PM adhering to the oxidation catalyst 44 cannot be removed even if the load increase control is executed.

Next, a second embodiment of the working machine of the present invention will be described with reference to FIGS. 4 and 5. FIG. 4 is a block diagram showing an exhaust gas treatment system and a hydraulic system according to a second embodiment of the work machine of the present invention. FIG. 5 is a flowchart showing an example of a procedure for load increase control by a controller that constitutes a part of a second embodiment of the work machine of the present invention shown in FIG. In addition, in FIGS. 4 and 5, those having the same reference numerals as those shown in FIGS. 1 to 3 have the same parts, and thus detailed description thereof will be omitted.

The second embodiment of the work machine of the present invention differs from the first embodiment in that the hydraulic excavator 1 is a hybrid type and has a generator motor system, and the controller 80A is hydraulic. The load increase control is performed not for the system 50 but for the generator motor system.

Specifically, in FIG. 4, the hydraulic excavator 1 is a power generation motor 72, a power storage device 72 that transfers power between the power generation motor 71 connected to the engine 41, and the power generation motor 71, and a power storage device 72. It is provided with a power control device (hereinafter referred to as PCU (power control unit)) 73 that controls the operation of the generator motor 71 by controlling the charging and discharging of the power generation motor 71.

The generator motor 71 is capable of both generator operation and motor operation. That is, it is possible to perform a generator operation that functions as a load device driven by the engine 41 to generate electricity and an electric motor operation that assists the drive of the engine 41 and the hydraulic pump 51. The generated electric power generated by the generator motor 71 is stored in the power storage device 72 via the PCU 73. On the other hand, when assisting the driving of the engine 41 and the hydraulic pump 51, the electric power of the power storage device 72 is supplied via the PCU 73 to drive the engine 41 and the hydraulic pump 51. The generator motor 71 is provided with a generator motor rotation speed detection device 74 that detects the actual rotation speed of the generator motor 71. The generator motor rotation speed detection device 74 is composed of, for example, an angular velocity sensor, and outputs a detection signal of the actual generator motor rotation speed to the PCU 73.

The power storage device 72 is composed of, for example, a capacitor, a battery, or the like, and is electrically connected to the generator motor 71 via the PCU 73. The power storage device 72 charges the generated electric power of the generator motor 71, and discharges the charged electric power to the generator motor 71.

The PCU 73 converts direct current and alternating current between the power storage device 72 and the generator motor 71, and lowers or boosts the direct current power. Specifically, at the time of power generation of the generator motor 71, after converting the AC power generated from the generator motor 71 into DC power, the DC power is stepped down and supplied to the power storage device 72. On the other hand, when the generator motor 71 is driven as an electric motor, the DC power from the power storage device 72 is boosted, and then the DC power is converted into AC drive power and supplied to the generator motor 71.

Further, the PCU 73 controls so that the torque of the generator motor 71 becomes the target torque from the controller 80A. In this case, torque control is performed by controlling the command current to the inverter (not shown) that drives the generator motor 71. Further, the PCU 73 can also control the rotation speed to generate the torque of the generator motor 71 so that the actual rotation speed of the generator motor 71 matches the target generator motor rotation speed from the controller 80A.

In addition to controlling the hydraulic system 50, the controller 80A controls the torque (absorption torque or assist torque) and the rotation speed of the generator motor 71 via the PCU 73. In the present embodiment, in addition to the output of the target engine speed to the engine control unit 42, the target torque or the target generator motor speed is output to the PCU 73.

The storage unit 91, the non-operation state determination unit 92, and the control end determination unit 94 of the controller 80A have the same functions as those in the first embodiment. On the other hand, when the non-operation state determination unit 92 determines that the non-operation state of the aircraft continues for the first time S1, the load control unit 93A of the controller 80A does not control the configuration of the hydraulic system 50. By preferentially controlling the generator motor 71 via the PCU 73, load increase control is performed to increase the load (power) of the generator motor 71 from that at the time of the determination.

Specifically, the load control unit 93A outputs the target torque to the PCU 73 to operate the generator motor 71 as a generator. Further, the load control unit 93A can operate the generator motor 71 as a generator by setting a target generator motor speed smaller than the target engine speed at the time of the determination and outputting it to the PCU 73. is there. The greater the deviation between the target engine speed and the target generator motor speed, the greater the load on the generator motor 71.

However, if the remaining charge of the power storage device 72 is sufficient, the generator motor 71 may not be able to operate as a generator. In this case, the controller 80A can perform load increase control for the hydraulic system 50 as in the first embodiment. It is also conceivable that the controller 80A sets a high target engine speed and controls the speed of the engine 41 via the engine control unit 42 to increase the load on the engine.

Next, an example of the procedure for load increase control by the controller constituting the second embodiment of the work machine of the present invention will be described with reference to FIGS. 4 and 5.

The controller 80A shown in FIG. 4 first determines whether or not the non-operating state (P ≦ Pt) of the airframe continues for the first time S1 based on the detection result P from the second pressure detecting device 62 (. Step S10 shown in FIG. 5). This determination is to determine whether PM (mainly SOF) is attached to the oxidation catalyst 44, and is the same as in the case of the first embodiment, and thus the description thereof will be omitted.

If YES in step S10, the controller 80A performs load increase control for operating the generator motor 71 as a generator via the PCU 73 in order to remove PM that is assumed to be attached to the oxidation catalyst 44 (FIG. Step S20A shown in 5).

Specifically, the load control unit 93A of the controller 80A outputs the target torque to the PCU 73. As a result, the PCU 73 controls the inverter (not shown) that drives the generator motor 71 so that the absorption torque of the generator motor 71 becomes the target torque from the controller 80A. As a result, the engine 41 is further loaded with the absorption torque of the generator motor 71, and the temperature of the exhaust gas of the engine 41 rises. Therefore, PM can be removed before PM is excessively attached to the oxidation catalyst 44.

Further, the load control unit 93A can output to the PCU 73 a target generator motor rotation speed lower than the target engine speed when it is determined that the non-operating state of the airframe is continuing. As a result, the PCU 73 controls the generator motor 71 so that the actual rotation speed of the generator motor 71 matches the target generator motor rotation speed from the load control unit 93A. In this case, since the generator motor 71 rotates in the vicinity of the target generator motor rotation speed lower than the target engine speed, the engine 41 also rotates in the vicinity of the target generator motor rotation speed together with the generator motor 71. On the other hand, the engine 41 is controlled by the engine control unit 42 so that the actual rotation speed of the engine 41 matches the target engine rotation speed. Therefore, it is necessary to increase the engine output because the control for increasing the actual rotation speed of the engine 41 is executed by the deviation between the target engine rotation speed and the target generator motor rotation speed. In other words, the load on the engine 41 is increasing. Also in this case, since the temperature of the exhaust gas rises, the PM can be removed before the PM excessively adheres to the oxidation catalyst 44.

After starting the load increase control for the generator motor 71, the controller 80A determines the end of the load increase control in steps S30 to S40 as in the case of the first embodiment. In some cases, as in the case of the first embodiment, the determination of the state in which PM removal in steps S30 and S60 is impossible is performed. When the state in which PM removal is impossible continues, the notification in step S70 is performed as in the case of the first embodiment. At the end of the load increase control (step S50A shown in FIG. 5), the load control unit 93A of the controller 80A controls the generator motor 71 so as to return to the state before the load increase control.

According to the second embodiment of the working machine of the present invention described above, the PM is removed from the oxidation catalyst 44 before the PM excessively adheres to the oxidation catalyst 44, as in the first embodiment described above. be able to.

Further, in the present embodiment, the hydraulic pump 51 in which the load device is driven by the engine 41 and the generator electric motor 71 capable of both the operation of the generator driven by the engine 41 and the electric motor assisting the engine 41 are used. The controller 80 is configured, and the generator 80 operates the generator motor 71 as a generator, and the load of the generator motor 71 is increased from the time of the determination (when it is determined that the non-operating states of the aircraft 2, 3 and 4 are continuing). By doing so, the load increase control is performed. According to this configuration, when the PM adhering to the oxidation catalyst 44 is removed, the generator motor 71 operates as a generator to charge the power storage device 72, so that the first embodiment for controlling the hydraulic system The energy loss can be reduced as compared with.

The present invention is not limited to the present embodiment, and includes various modifications. The above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. It is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

For example, in the first and second embodiments described above, an example in which the aftertreatment device 43 is composed of the oxidation catalyst 44 and the collection filter 45 is shown. However, the aftertreatment device can be configured to include a NOx purification device in addition to the oxidation catalyst 44 and the collection filter 45. It is also possible to configure the aftertreatment device with the oxidation catalyst 44 and the NOx purification device, and omit the collection filter 45. The aftertreatment device may be configured to include at least the oxidation catalyst 44.

Further, in the above-described embodiment, an example is shown in which the operation state (operation amount and operation direction) of the operation lever device 64 is detected by the operation pilot pressure generated by the operation lever device 64. However, when the operating lever device as the operating device is an electric type, the operating state of the operating lever device is detected by an electric signal (voltage) output from the operating lever device. In this case, as the operation state detection device for detecting the operation state of the operation device, an electric operation lever device (operation device) functions instead of the second pressure detection device 62.

In this configuration, the controllers 80 and 80A continue the non-operating state of the airframe for the first time S1 based on the detection result (voltage) from the electric operating device in step S10 shown in FIGS. 3 and 5. Judge whether or not. Specifically, the non-operating state determination unit 92 continues within a predetermined voltage range (that is, the non-operating state of the airframe) in which the voltage value from the electric operating device is stored in the storage unit 91. The first duration t1 is measured, and it is determined whether or not the measured first duration t1 has reached the first time S1 stored in the storage unit 91. If the airframe whose voltage value is outside the predetermined voltage range is in the operating state, or if the first duration t1 is less than the first time S1, that is, if NO, step S10 is repeated again.

Further, in the above-described embodiment, as the operation state detection device for detecting the operation state of the operation device, the second pressure detection device 62 for detecting the operation pilot pressure generated by the operation lever device 64 as the operation device is used. The configuration has been described as an example. However, as the operation state detection device, a position detection device 66 that detects the operation position (lock position L or unlock position U) of the gate lock lever 65 as the operation device can also be used. When the operation position detected by the position detection device 66 is at the lock position L, the machine cannot be operated via the operation lever device 64, so that the machine is not operated. Can be regarded as.

In this configuration, in step S10 shown in FIGS. 3 and 5, the controllers 80 and 80A have a first non-operating state of the airframe based on the detection result (lock position L or unlock position U) from the position detection device 66. It is determined whether or not the time S1 continues. Specifically, the non-operation state determination unit 92 measures and measures the first duration t1 in which the detection position from the position detection device 66 continues at the lock position L (that is, the non-operation state of the aircraft). It is determined based on whether or not the first duration t1 has reached the first time S1 stored in the storage unit 91. If the detection position is the unlock position U, or if the first duration t1 is less than the first time S1, that is, if NO, step S10 is repeated again.

Further, in the first embodiment described above, the controller 80 controls the load increase to increase the load (power) of the hydraulic pump 51, thereby increasing the exhaust gas temperature of the engine 41 and sorbing the SOF from the oxidation catalyst 44. An example of removal has been described. Further, in the second embodiment described above, the controller 80A controls the load increase to increase the load (power) of the generator motor 71, thereby increasing the exhaust gas temperature of the engine 41 and converting the SOF from the oxidation catalyst 44. An example of removal has been described. On the other hand, the controller performs load increase control that increases only the target engine speed output to the engine control unit 42 without increasing the load (power) of the load device such as the hydraulic pump 51 or the generator motor 71. Therefore, it is also possible to raise the exhaust gas temperature of the engine 41 to remove the SOF from the oxidation catalyst 44.

In this case, in step S10 shown in FIGS. 3 and 5, the non-operation state of the aircraft is set to the first time based on the detection result P (operation pilot pressure) from the second pressure detection device 62 as the operation state detection device. When it is determined that S1 is continuing (YES), the engine control is performed by setting a target engine speed higher than the target engine speed at the time of the judgment without controlling the hydraulic system 50 and the generator motor 71. The load increase control to output to the unit 42 is performed. As a result, the engine control unit 42 is injected into the cylinder of the engine 41 so that the actual rotation speed of the engine 41 from the engine rotation speed detection device 47 matches the target engine rotation speed higher than that at the time of the determination from the controller. Control the fuel injection speed. Therefore, the fuel injection amount increases and the exhaust gas temperature of the engine 41 rises, so that the SOF can be removed from the oxidation catalyst 44.

1 ... Hydraulic excavator (working machine), 2 ... Lower traveling body (machine), 4 ... Upper rotating body (body), 3 ... Front work machine (machine), 41 ... Engine, 42 ... Engine control unit, 44 ... Oxidation catalyst , 46 ... exhaust pipe (exhaust path), 48 ... exhaust gas temperature detector (temperature detector), 50 ... hydraulic system, 51 ... hydraulic pump (load device), 62 ... second pressure detector (operation state detector), 64 ... Operation lever device (operation device), 65 ... Gate lock lever (operation device), 66 ... Position detection device (operation state detection device), 71 ... Power generator (load device), 80, 80A ... Controller, 100 ... Notification apparatus

Claims (5)

With the engine
An oxidation catalyst that is arranged in the exhaust gas path of the engine and promotes oxidation of components contained in the exhaust gas of the engine.
The load device driven by the engine and
An engine control unit that controls the engine based on the target engine speed,
In a work machine provided with a controller that controls the operation of the machine body according to the operation of the operating device and outputs the target engine speed to the engine control unit.
An operation state detection device for detecting the operation state of the operation device is provided.
Based on the detection result from the operation state detection device, the controller determines whether or not the time during which the non-operation state of the aircraft continues has reached a preset first time, and the first A work machine characterized in that when it is determined that the time has been reached, load increase control is performed to increase the load of the load device or the target engine speed from that at the time of the determination. In the work machine according to claim 1,
The load device is a hydraulic pump that constitutes a part of a hydraulic system that drives the airframe.
The controller is a work machine characterized in that the load increase control is performed by increasing at least one of the discharge pressure and the push-out volume of the hydraulic pump from the time of the determination. In the work machine according to claim 1,
The load device is
The hydraulic pump driven by the engine and
It is composed of a generator driven by the engine and a generator motor capable of both operation of the motor assisting the engine.
The controller is a work machine characterized in that the load increase control is performed by operating the generator motor as a generator and increasing the load of the generator motor from the time of the determination. In the work machine according to claim 1,
Further provided with a temperature detection device installed on the upstream side of the oxidation catalyst in the exhaust gas path and detecting the temperature of the exhaust gas discharged from the engine.
In the load increase control, the controller determines whether or not the time during which the detection temperature of the temperature detection device continues at a predetermined threshold value or higher reaches a preset second time, and determines whether or not the predetermined second time has been reached. A work machine characterized in that the load increase control is terminated when it is determined that the time continuing above the threshold value has reached the second time. In the work machine according to claim 4,
A notification device for notifying the operator based on the notification command from the controller is further provided.
In the load increase control, the controller determines whether or not the time at which the detection temperature of the temperature detection device continues below the predetermined threshold value reaches a preset third time, and determines whether or not the predetermined third time has been reached. When it is determined that the time continuing below the threshold value of is reached the third time, the load increase control is terminated and the time continuing above the predetermined threshold value is the second time. A work machine characterized in that a notification command for notifying the operator that the load increase control ends without reaching the time is output to the notification device.

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