JP2005207397A - Engine control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control method capable of preventing an engine from being stopped which leads to the shortage of the service life and the failure of machines such as engines and hydraulic circuit parts. <P>SOLUTION: In a machine for supplying hydraulic oil into the hydraulic circuit for working by a pump driven by an engine, measuring the temperature of cooling water while cooling the engine by the cooling water of a radiator, and measuring the temperature of the hydraulic oil while cooling the hydraulic oil in the hydraulic circuit by an oil cooler, after a specified time is elapsed after the hydraulic circuit for working is brought into a non-operated state, the speed of the engine is lowered from a set speed to a wait speed. By resetting the non-operated state, the speed of the engine is returned to the set speed. By continuing the non-operated state, the radiator and the oil cooler are operated at the wait speed of the engine for a specified time, and the engine is stopped under the condition that the temperature of the hydraulic oil and the temperature of the cooling water are lowered from their respective specified values. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an engine control method characterized by an engine stop method.

In construction machines, particularly hydraulic excavators, there is often a situation where operation is not continuous and the engine is idle. This is the case when one operator is performing in parallel with other work, waiting for a dump, waiting for the worker status around the machine. In the meantime, fuel is consumed, which should be improved from the standpoint of reducing fuel consumption and from the standpoint of reducing environmental impact. In order to improve this, conventionally, the engine is automatically stopped based on only the operation state detection centered on the hydraulic lock operation (or using a timer based on it) (for example, patents). References 1, 2, 3, 4).
Japanese Patent Laying-Open No. 2003-307142 (page 5-7, FIG. 1-2) JP 2000-96627 A (page 6-8, FIG. 3) JP 2001-41069 A (page 2-4, FIG. 4) JP-A-5-44517 (page 3-5, FIG. 1)

  However, when the machine is automatically stopped, the machine life may be shortened or a failure may occur if the machine is automatically stopped before certain conditions for stopping the machine are met. For example, when the hydraulic oil temperature (hereinafter referred to as “oil temperature”) is in a high temperature state during high load operation or high temperature operation, or the engine coolant temperature (hereinafter referred to as “water temperature”) is in a high temperature state. In this case, if the machine is stopped, the mechanical life of the engine, hydraulic circuit parts, etc. may be shortened or it may lead to failure.

  In other words, in the conventional techniques described in the cited documents 1, 2, 3, and 4, the engine is stopped without considering the hydraulic oil temperature and the coolant temperature of the machine. There is a fear.

  The present invention has been made in view of these points, and an object of the present invention is to provide an engine control method capable of shortening the mechanical life of an engine, a hydraulic circuit component, or the like or preventing an engine stop leading to a failure.

  According to the first aspect of the present invention, hydraulic oil is supplied to a working hydraulic circuit from a pump driven by the engine, and the temperature of the cooling water is measured while the engine is cooled by the cooling water of the radiator, and the hydraulic oil of the hydraulic circuit is supplied. In a machine that measures the temperature of hydraulic oil while being cooled by an oil cooler, the engine hydraulic speed is reduced from the set rotational speed to the standby rotational speed after a predetermined period of time when the working hydraulic circuit is in a non-operating state. The engine speed is restored to the set speed by releasing the operating condition, and the radiator and oil cooler are operated for at least a predetermined time at the engine standby speed by continuing the non-operating condition, and the temperature of the hydraulic oil and the temperature of the cooling water Is an engine control method for stopping the engine on the condition that the pressure drops below a specified value, and the hydraulic oil and cooling Since the engine is stopped under no load conditions due to a drop in water temperature, it is possible to reduce machine damage and reduce fuel consumption and environmental load. As a result, the working hydraulic circuit becomes inoperative, the engine speed decreases from the set rotational speed to the standby rotational speed, and the radiator and oil cooler are operated at least for a predetermined time at the engine standby rotational speed. This waits for the temperature of the water and the temperature of the cooling water to drop below the specified values, thereby prolonging the mechanical life of the engine and hydraulic circuit components and preventing failure.

  According to a second aspect of the present invention, hydraulic oil is supplied to a working hydraulic circuit from a pump driven by the engine, and the temperature of the cooling water is measured while the engine is cooled by the cooling water of the radiator. In a machine that is cooled by an oil cooler, the engine hydraulic speed is reduced from the set rotational speed to the standby rotational speed after the lapse of a predetermined time after the working hydraulic circuit is in a non-operating state, and the engine rotation is released by releasing the non-operating state The engine is operated under the condition that the speed is returned to the set rotational speed, the radiator and the oil cooler are operated for at least a predetermined time at the engine standby rotational speed by continuing the non-operation state, and the temperature of the cooling water falls below the specified value. This is an engine control method that stops the engine, and stops the engine's operation under no load on condition that the cooling water temperature falls. Therefore, it is possible to reduce the damage to the machine, reduce the fuel consumption and the environmental load.In particular, as a condition for stopping the engine, the working hydraulic circuit becomes inoperative and the engine speed is reduced. Decreases from the set rotation speed to the standby rotation speed, and at this engine standby rotation speed, the radiator and the oil cooler are operated for at least a predetermined time, and the temperature of the cooling water waits for the temperature to fall below the specified value. This will extend the machine life of parts and prevent failures.

  According to a third aspect of the present invention, hydraulic oil is supplied to a working hydraulic circuit from a pump driven by the engine, the engine is cooled by cooling water of the radiator, and the hydraulic oil is cooled while being cooled by the oil cooler. In a machine that measures the temperature of the engine, the engine hydraulic speed is reduced from the set rotational speed to the standby rotational speed after a predetermined period of time when the working hydraulic circuit is in a non-operating state, and the engine is rotated by releasing the non-operating state. The engine is operated under the condition that the speed is returned to the set rotational speed, the radiator and the oil cooler are operated for at least a predetermined time at the engine standby rotational speed by continuing the non-operation state, and the temperature of the hydraulic oil falls below a specified value. This is an engine control method that stops the engine, and stops operation under no-load condition on condition that the temperature of the hydraulic oil drops. Therefore, it is possible to reduce the damage to the machine, reduce the fuel consumption and the environmental load.In particular, as a condition for stopping the engine, the working hydraulic circuit becomes inoperative and the engine speed is reduced. Decreases from the set rotational speed to the standby rotational speed, and the radiator and oil cooler are operated for at least a predetermined time at the standby rotational speed of the engine, and waits for the temperature of the hydraulic oil to fall below the specified value. This will extend the machine life of parts and prevent failures.

  According to the first aspect of the present invention, since the engine is stopped from operating under a no load condition on the condition that the temperature of the hydraulic oil and the cooling water is lowered, the damage to the machine is reduced, and the fuel consumption and the environmental load are reduced. In particular, as a condition for stopping the engine, the working hydraulic circuit is in an inoperative state, the engine rotational speed is reduced from the set rotational speed to the standby rotational speed, and at least a predetermined value is set at this engine standby rotational speed. During the time, the radiator and the oil cooler are operated, and the temperature of the hydraulic oil and the temperature of the cooling water are waited for lower than the specified values. Therefore, the mechanical life of the engine, hydraulic circuit components, etc. can be extended or failure can be prevented.

  According to the second aspect of the present invention, since the engine is stopped in a no-load state on condition that the temperature of the cooling water is lowered, it is possible to reduce damage to the machine and to reduce fuel consumption and environmental load. In particular, as a condition for stopping the engine, the working hydraulic circuit is in an inoperative state, and the engine rotation speed is reduced from the set rotation speed to the standby rotation speed. At this engine standby rotation speed, the radiator is at least for a predetermined time. In addition, since the oil cooler is operated and the temperature of the cooling water waits for the temperature to fall below the specified value, it is possible to extend the mechanical life of the engine and hydraulic circuit components and to prevent failure.

  According to the invention described in claim 3, since the operation of the engine in the no-load state is stopped on the condition that the temperature of the hydraulic oil is lowered, it is possible to reduce the damage to the machine and to reduce the fuel consumption and the environmental load. In particular, as a condition for stopping the engine, the working hydraulic circuit is in an inoperative state, and the engine rotation speed is reduced from the set rotation speed to the standby rotation speed. At this engine standby rotation speed, the radiator is at least for a predetermined time. In addition, since the oil cooler is operated and the temperature of the hydraulic oil is lowered from the specified value, the mechanical life of the engine, hydraulic circuit components, and the like can be extended and failure can be prevented.

  Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS. 1 to 3, another embodiment shown in FIG. 4, and still another embodiment shown in FIG. 5. explain.

  FIG. 2 shows a hydraulic excavator as a working machine according to the present invention. An upper swing body 13 is turnably provided on a lower traveling body 11 via a turning section 12, and the upper swing body 13 is provided with an engine, a hydraulic pump. A cab 15 that covers the operator's seat is mounted along with a power unit 14 such as a generator, and a working device 16 that performs excavation work is mounted.

  The lower traveling body 11 is provided with a traveling motor (not shown) as a hydraulic actuator that drives a sprocket 18 around which the crawler belt 17 is wound. The swivel portion 12 is a hydraulic actuator that drives the upper revolving body 13 to rotate. And a boom cylinder 16bmc as a hydraulic actuator for rotating the boom 16bm in the vertical direction with respect to the upper swing body 13, and an arm 16am with respect to the boom 16bm. An arm cylinder 16amc is provided as a hydraulic actuator that rotates the bucket 16 and a bucket cylinder 16bkc is provided as a hydraulic actuator that rotates the bucket 16bk relative to the arm 16am. On the side surface of the boom 16bm, an illuminating lamp (hereinafter referred to as “light”) 19 as an electrical component is provided.

  FIG. 3 is a block diagram of a control system for controlling the engine of the power unit 14. The accelerator for setting the rotational speed of the engine 22 (hereinafter referred to as “rotational speed”) to the input unit of the controller 21. At least a predetermined time has elapsed since the engine speed setting unit 23 such as a dial is connected and the engine speed detection unit 24 for detecting the engine speed is connected, and the engine speed decreases from the set speed to the standby speed. An engine auto stop switch 25 for starting or canceling an engine auto stop circuit in the controller 21 that automatically stops the engine 22 when a certain condition is met is connected, and the output portion of the controller 21 is connected to the engine 22 An engine control unit 26 such as a governor for controlling the engine start, stop, and engine speed provided is connected.

  Furthermore, a generator 27 driven by the engine 22 is connected to a battery 28. The battery 28 is connected to the controller 21 as a power source and to the input portion of the controller 21 via the key switch 29. Electrical components such as a light 19, an automatic air conditioner (hereinafter referred to as "auto air conditioner") 31, and a radio 32 are connected to the output section. The controller 21 has a function of turning on / off the power for driving the engine connected to the engine control unit 26 and a function of turning on / off the power of electrical components such as the light 19 separately.

  Further, the main pump 35 as a pump driven by the engine 22 is connected to the traveling motor, the swing motor, the boom cylinder 16bmc, the arm cylinder 16amc, the bucket cylinder 16bkc, etc. A primary pipe 39 of a pilot pump 38 that is connected to a hydraulic main circuit 37 as a working hydraulic circuit for controlling the hydraulic actuator and is driven by the engine 22 is provided in the hydraulic main circuit 37. The control valve (not shown) is connected to a pilot circuit 40 as a working hydraulic circuit for controlling a pilot pressure for piloting a spool corresponding to various hydraulic actuators.

  The pilot circuit 40 includes a pilot valve (so-called remote control valve) 43 in which a primary pipe 39 of a pilot pump 38 is manually operated by an operating device 42 such as an operating lever or a pedal via an electromagnetically operated hydraulic lock valve 41. The secondary port of the pilot valve 43 is connected to the end face of a spool corresponding to various hydraulic actuators of a control valve (not shown) provided in the hydraulic main circuit 37 via a secondary pipe 44. Led.

  The hydraulic lock valve 41 opens and closes the primary piping 39 of the pilot pump 38 by a hydraulic lock switch 45 that is turned on / off by a hydraulic lock lever (not shown) that blocks or opens the entrance / exit of the cab 15. Control. Further, the secondary piping 44 of the pilot valve 43 is provided with a pressure sensor 46 for detecting the operation status of the operating device 42 based on the value of the pilot secondary pressure, and this pressure sensor 46 is connected to the controller 21. .

  Further, the hydraulic oil in the hydraulic circuit is cooled by an oil cooler 51, and the engine 22 is cooled by a radiator 52. A cooling fan 53 driven by the engine 22 faces the oil cooler 51 and the radiator 52. Installed. In addition, an oil temperature sensor 54 for measuring the temperature of hydraulic oil (hereinafter referred to as “oil temperature”) in a common oil tank into which the suction side pipes of the main pump 35 and the pilot pump 38 are inserted, and cooling of the radiator 52 A water temperature sensor 55 that measures the temperature of the water (hereinafter referred to as “water temperature”) is connected to the input section of the controller 21 until the oil temperature is lower than the specified oil temperature and the water temperature is lower than the specified water temperature. Since the engine 22 needs to be driven, an oil temperature / water temperature setting unit 56 for setting the specified oil temperature and the specified water temperature is connected to the input unit of the controller 21, respectively.

  Furthermore, a timer circuit for shutting down the engine power supply and for shutting down the engine power supply for reducing the engine speed is provided in the controller 21. These timer times are preset (selected) in the input section of the controller 21. A timer setting unit 57 for connecting is connected. Also, a warning unit 58 such as a monitor or a buzzer that gives an engine stop warning before the engine 22 is automatically stopped when the engine auto stop circuit in the controller 21 is started is connected to the output unit of the controller 21. .

  Next, functions and control procedures of the controller 21 will be described with reference to the flowchart shown in FIG.

(Step 1)
The controller 21 uses the pressure sensor 46 to determine the operating status of the operating device 42. That is, when the operation unit 42 is operated, pilot pressure is output from the pilot valve 43 to each spool of the control valve in the hydraulic main circuit 37, and the main body 35 operates through each spool of the control valve. Therefore, it is determined by the pressure signal from the pressure sensor 46 whether or not it is in such a working state.

(Step 2)
When the operation device 42 is operated, the engine speed set by the engine speed setting unit 23 (hereinafter referred to as “set speed”) is instructed from the controller 21 to the engine control unit 26 to detect the engine speed. The actual rotational speed detected by the unit 24 is fed back to the controller 21 and controlled so as to obtain the set rotational speed.

(Steps 3 and 4)
When the operation unit 42 is not operated in step 1 and is not operated, the controller 21 starts a built-in timer from the time when the operation unit 42 is not operated, and is a rule preset (selected) by the timer setting unit 57. It is determined whether or not the time t1 has elapsed, and when the specified time t1 has elapsed, the engine speed is reduced from a relatively high speed setting speed to a low standby speed.

(Steps 5 and 6)
The controller 21 determines whether the engine auto stop switch 25 is on (the auto stop function can be activated) or off (the auto stop function cannot be activated), and when the off state is detected, the engine speed is maintained at the standby speed. To do.

(Step 7)
If the controller 21 detects in step 5 that the engine auto stop switch 25 is on (the auto stop function can be activated), the controller 21 determines whether the hydraulic lock switch 45 is on (the aircraft cannot be operated) or off (the aircraft can be operated). When the OFF state of the hydraulic lock switch 45 is detected, the engine speed is maintained at the standby speed in preparation for work.

(Steps 8, 9, 10)
When the controller 21 senses the ON state of the hydraulic lock switch 45, it starts an engine auto-stop timer. That is, the controller 21 determines whether or not a predetermined time t2 preset (selected) by a timer has elapsed since the hydraulic lock switch 45 is turned on, and when the predetermined time t2 has elapsed, the oil temperature sensor 54 and the water temperature sensor The oil temperature and water temperature are measured by 55, and it is determined whether the measured oil temperature and water temperature are greater than or less than the oil temperature specified value and water temperature specified value preset (selected) by the oil temperature / water temperature setting unit 56. If the specified value is exceeded or the specified water temperature is exceeded, the oil cooler 51 and the radiator 52 are operated to maintain the engine speed at the standby speed in order to cool the hydraulic oil and cooling water. Repeat the measurement. The measurement of the oil temperature and the water temperature may be started before the timer is started.

(Step 11)
When the measured oil temperature and water temperature are lower than the oil temperature / water temperature set value preset (selected) by the oil temperature / water temperature setting unit 56, the controller 21 monitors or buzzers before the engine 22 is automatically stopped. The engine stop warning is output to the warning unit 58 such as.

(Steps 12 and 13)
The controller 21 maintains the engine rotational speed at the standby rotational speed until the predetermined time t3 preset (selected) by the timer elapses from the engine stop warning, but when the predetermined time t3 elapses from the engine stop warning, The engine 22 is stopped.

(Steps 14 and 15)
After the engine is stopped, the controller 21 shuts off the power related to driving of the engine 22 with respect to the engine control unit 26 when a predetermined time t4 preset (selected) by a timer has elapsed.

  As described above, the hydraulic oil is supplied to the working hydraulic circuits 37 and 40 from the pumps 35 and 38 driven by the engine 22, and the cooling water temperature is cooled by the water temperature sensor 55 while the engine 22 is cooled by the cooling water of the radiator 52. In the machine that measures the hydraulic oil temperature by the oil temperature sensor 54 while cooling the hydraulic oil in the hydraulic circuits 37 and 40 by the oil cooler 51, the controller 21 does not have the hydraulic circuits 37 and 40 for work. After a predetermined time has elapsed after entering the operation state, the rotation speed of the engine 22 is reduced from the set rotation speed to the standby rotation speed, and when the non-operation state is released, the rotation speed of the engine 22 is returned to the set rotation speed. By continuing, the radiator 52 and the oil cooler 51 are operated for at least a predetermined time at the standby rotational speed of the engine 22, and the temperature of the hydraulic oil and the temperature of the cooling water are lowered from the specified values. Stop engine 22

  And since the operation of the engine 22 in the no-load state is stopped on condition that the temperature of the hydraulic oil and the cooling water is lowered, it is possible to reduce the damage to the machine, and to reduce the fuel consumption and the environmental load. As a condition for stopping the engine 22, the working hydraulic circuits 37 and 40 are not operated, and the rotational speed of the engine 22 is reduced from the set rotational speed to the standby rotational speed. The standby rotational speed of the engine 22 is at least a predetermined time. Operates the radiator 52 and the oil cooler 51 and waits for the coolant temperature and hydraulic oil temperature to drop below the specified values, thus prolonging the mechanical life of the engine 22 and hydraulic circuit components and preventing malfunctions. it can.

  Next, FIG. 4 shows another embodiment in which step 9 in the embodiment shown in FIG. 1 is omitted, and the other steps are the same as those in the embodiment shown in FIG. 21 determines the operating state of the operating device 42 by the pressure sensor 46 (step 1), and controls the engine speed to the set rotational speed (step 2) when the operating device 42 is operated. When the non-operating state is reached, it is determined whether or not the specified time t1 has elapsed since the time when the non-operating state was reached (step 3). The engine speed is lowered from the high speed setting speed to the low standby speed (step 4).

  The controller 21 determines whether the engine auto stop switch 25 is on (the auto stop function can be activated) or off (the auto stop function cannot be activated) (step 5), and when the off state is detected, waits for the engine speed. If the engine auto stop switch 25 is turned on (the auto stop function can be activated) in step 5, the hydraulic lock switch 45 is turned on (the aircraft cannot be operated) or off (the aircraft is not operated). When the hydraulic lock switch 45 is detected to be off, the engine speed is maintained at the standby speed in preparation for work (step 6). When an on-state is detected, the engine auto-stop timer is started and the hydraulic lock switch 45 is turned on. Preset in Ma (selected) has been specified time t2 it is determined whether the elapsed (Step 8).

  The controller 21 measures the water temperature of the radiator 52 by the water temperature sensor 55 when the predetermined time t2 preset (selected) by the timer has elapsed, and the measured water temperature is preset (selected) by the oil temperature / water temperature setting unit 56. (Step 9). If the water temperature is higher than the specified value, the oil cooler 51 and the radiator 52 are operated to reduce the operating oil and cooling water. Maintain the number of revolutions in standby and repeat the water temperature measurement. This water temperature measurement may be started before the timer is started.

  When the measured water temperature falls below the specified water temperature value preset (selected) by the oil temperature / water temperature setting unit 56, the controller 21 notifies the warning unit 58 such as a monitor or buzzer before the engine 22 is automatically stopped. A stop warning is output (step 10), and the engine speed is maintained at the standby speed until the specified time t3 preset (selected) by the timer elapses from the engine stop warning. When t3 elapses, the engine 22 is stopped (steps 11 and 12), and after the engine is stopped, when a predetermined time t4 preset (selected) by a timer elapses, the power relating to driving of the engine 22 to the engine control unit 26 is supplied. Is blocked (steps 13 and 14).

  That is, hydraulic oil is supplied to the working hydraulic circuits 37 and 40 from the pumps 35 and 38 driven by the engine 22, and the temperature of the cooling water is measured by the water temperature sensor 55 while the engine 22 is cooled by the cooling water of the radiator 52. At the same time, in the machine that cools the hydraulic oil in the hydraulic circuits 37 and 40 by the oil cooler 51, the controller 21 controls the rotational speed of the engine 22 after the working hydraulic circuits 37 and 40 are in an inoperative state and a predetermined time has elapsed. The engine speed is reduced from the set speed to the standby speed, the engine 22 is returned to the set speed by releasing the non-operating condition, and the radiator 52 and the oil cooler 51 are operated at the standby speed of the engine 22 by continuing the non-operating condition. The engine 22 is stopped on the condition that the cooling water is measured for at least a predetermined time and the temperature of the cooling water measured by the water temperature sensor 55 falls below a specified value.

  Next, FIG. 5 shows still another embodiment in which step 10 in the embodiment shown in FIG. 1 is omitted, and other steps are the same as those in the embodiment shown in FIG. The controller 21 determines the operation state of the operating device 42 by the pressure sensor 46 (step 1), and controls the engine speed to the set rotational speed when the operating device 42 is operated (step 2). When the non-operating state in which 42 is not operated is determined, it is determined whether or not the specified time t1 has elapsed from the time when the non-operating state is reached (step 3). The rotational speed is reduced from a relatively high set rotational speed to a low standby rotational speed (step 4).

  The controller 21 determines whether the engine auto-stop switch 25 is on (the auto-stop function can be activated) or off (the auto-stop function cannot be activated) (step 5). Maintain the speed (step 6), and if the engine auto stop switch 25 is turned on (operable) in step 5, the hydraulic lock switch 45 is on (machine operation not possible) or off (machine operation is possible) (Step 7), and when the hydraulic lock switch 45 is turned off, the engine speed is maintained at the standby rotational speed in preparation for the work, and the hydraulic lock switch 45 is turned on. The engine auto-stop timer is started and the hydraulic lock switch 45 is turned on, and the preset time is set (selected) by the timer. t2 it is determined whether the elapsed (Step 8).

  The controller 21 measures the oil temperature by the oil temperature sensor 54 when the predetermined time t2 preset (selected) by the timer elapses, and the measured oil temperature is preset (selected) by the oil temperature / water temperature setting unit 56. If the oil temperature is above or below the specified oil temperature (step 9), if the oil temperature is above the specified value, the engine cooler 51 and the radiator 52 are operated to cool the hydraulic oil and cooling water. Keep the number at the standby rotation speed and repeat the oil temperature measurement. The oil temperature measurement may be started before the timer is started.

  When the oil temperature measured by the oil temperature sensor 54 falls below the specified oil temperature value set (selected) by the oil temperature / water temperature setting unit 56, the controller 21 can monitor or buzz before the engine 22 is automatically stopped. The engine stop warning is output to the warning section 58 (step 10), and the engine speed is maintained at the standby speed until a predetermined time t3 preset (selected) by the timer elapses from the engine stop warning, When the specified time t3 has elapsed from the engine stop warning, the engine 22 is stopped (steps 11 and 12). After the engine has stopped, when the specified time t4 preset (selected) by the timer has elapsed, the engine for the engine control unit 26 is The power supply related to the drive of 22 is cut off (steps 13 and 14).

  That is, hydraulic oil is supplied to the working hydraulic circuits 37 and 40 from the pumps 35 and 38 driven by the engine 22, and the engine 22 is cooled by the cooling water of the radiator 52, and the hydraulic oil of the hydraulic circuits 37 and 40 is oiled. In the machine that measures the temperature of the hydraulic oil with the oil temperature sensor 54 while being cooled by the cooler 51, the controller 21 determines that the rotational speed of the engine 22 after the working hydraulic circuits 37 and 40 have not been operated and a predetermined time has elapsed. Is reduced from the set rotational speed to the standby rotational speed, the rotational speed of the engine 22 is restored to the set rotational speed by releasing the non-operation state, and the radiator 52 and the oil cooler 51 are maintained at the standby rotational speed of the engine 22 by continuing the non-operation state. Is operated for at least a predetermined time, and the engine 22 is stopped on condition that the temperature of the hydraulic oil measured by the oil temperature sensor 54 falls below a specified value.

  As described above, the embodiment shown in FIG. 4 and the embodiment shown in FIG. 5 stop the operation of the engine 22 in the no-load state on condition that the temperature of the cooling water or the hydraulic oil is lowered. Machine damage can be reduced, and fuel consumption and environmental load can be reduced. In particular, as a condition for stopping the engine 22, the working hydraulic circuits 37 and 40 are not operated, and the rotational speed of the engine 22 is reduced from the set rotational speed to the standby rotational speed. The radiator 52 and the oil cooler 51 are operated for a predetermined time, and the embodiment shown in FIG. 4 waits for the temperature of the cooling water to drop below a specified value, and the embodiment shown in FIG. Since it waits for the oil temperature to fall below the specified value, it is possible to extend the mechanical life of the engine 22, hydraulic circuit components, etc., and to prevent failure.

  In contrast to the embodiment shown in FIG. 1 which monitors the temperature of both cooling water and hydraulic oil, the embodiment shown in FIG. 4 and the embodiment shown in FIG. It is only necessary to monitor the temperature of either one.

It is a flowchart which shows one Embodiment of the engine control method which concerns on this invention. It is a side view of a hydraulic excavator to which the engine control method is applied. It is a block diagram of the engine control apparatus for enforcing an engine control method same as the above. It is a flowchart which shows other embodiment of the engine control method which concerns on this invention. It is a flowchart which shows another embodiment of the engine control method which concerns on this invention.

Explanation of symbols

22 engine
35 Main pump as pump
37 Hydraulic main circuit as hydraulic circuit
38 Pilot pump as pump
40 Pilot circuit as hydraulic circuit
51 Oil cooler
52 Radiator

Claims (3)

Supply hydraulic oil to the working hydraulic circuit from the pump driven by the engine,
In a machine that measures the temperature of the cooling water while cooling the engine with the cooling water of the radiator and measures the temperature of the hydraulic oil while cooling the hydraulic oil in the hydraulic circuit with the oil cooler,
When the working hydraulic circuit is in a non-operating state and the predetermined time has elapsed, the engine rotation speed is reduced from the set rotation speed to the standby rotation speed,
By releasing the no-operation state, the engine speed is returned to the set speed,
To stop the engine on condition that the radiator and oil cooler are operated for at least a predetermined time at the engine's standby rotational speed by continuing the non-operation state, and the temperature of the hydraulic oil and the temperature of the cooling water are lower than the specified values. A characteristic engine control method. Supply hydraulic oil to the working hydraulic circuit from the pump driven by the engine,
In a machine that measures the temperature of the cooling water while cooling the engine with the cooling water of the radiator and cools the hydraulic circuit hydraulic oil with the oil cooler,
When the working hydraulic circuit is in a non-operating state and the predetermined time has elapsed, the engine rotational speed is reduced from the set rotational speed to the standby rotational speed,
By releasing the no-operation state, the engine speed is returned to the set speed,
Engine control characterized in that the radiator and oil cooler are operated for at least a predetermined time at the engine's standby rotational speed by continuing the non-operation state, and the engine is stopped on condition that the cooling water temperature falls below a specified value. Method. Supply hydraulic oil to the working hydraulic circuit from the pump driven by the engine,
In a machine that measures the temperature of the hydraulic oil while cooling the hydraulic oil in the hydraulic circuit with the oil cooler while cooling the engine with the cooling water of the radiator,
When the working hydraulic circuit is in a non-operating state and the predetermined time has elapsed, the engine rotation speed is reduced from the set rotation speed to the standby rotation speed,
By releasing the no-operation state, the engine speed is returned to the set speed,
Engine control characterized in that the radiator and oil cooler are operated for at least a predetermined time at the engine's standby rotational speed by continuing the no-operation state, and the engine is stopped on condition that the temperature of the hydraulic oil falls below a specified value. Method.

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