JP2019173567A - Construction machine - Google Patents

Abstract

To prevent erroneous operation of a notification device caused by an erroneous detection at a water level sensor when a water separation unit receives high level vibration due to drilling and travelling or the like, provide a high level acknowledgement of serious condition about outflow of water stored in the water separation unit, enable the operator to carry out drainage work of the water separation unit in a compulsory manner while restricting influence against workability to minimum.SOLUTION: An engine controller 40 performs a fail-safe control including an engine speed limit control that makes an input of a water level arrival signal from a water level sensor effective when a key signal of a power supply ON is inputted before starting an engine 1 and drives a notification device 22 when the water level arrival signal is inputted and at the same time decreasing the engine speed of the engine 1 and an engine speed limit control for decreasing the engine speed of an engine 1 and further an engine stop control for stopping the engine 1 upon elapsing of predetermined time.SELECTED DRAWING: Figure 3

Description

  The present invention detects a water separation device that separates water contained in fuel, and that the water level separated and stored by the water separation device has reached a predetermined height, and a water level arrival signal (switch signal) And a water level detection device that outputs a water level detection device.

  As this type of prior art, those described in Patent Document 1 and Patent Document 2 are known.

  The prior art described in Patent Document 1 includes an operation determination unit that determines whether or not a construction machine is operating in a work machine including a water separation device and a water level detection device (water level sensor). The water level detection device is enabled only when it is determined that it is not operating, so that the malfunction of the notification device due to erroneous detection of the water level detection device is not caused.

  The prior art described in Patent Document 2 is a work machine including a water separation device and a water level detection device (water level sensor), even though the water level detection device detects that the water level has reached a predetermined height. When the water separator is not drained, the engine speed is automatically reduced after a predetermined time so that the operator can recognize the seriousness of the outflow of water stored in the water separator. ing.

JP 2013-144906 A

Special table 2013-534294 gazette

  If water has accumulated in the water separator and the water level detector has detected that the water level has reached a predetermined height, the operator does not drain the water separator. The spilled water can flow into the engine and cause fatal damage to injectors and fuel systems. In particular, when poor fuel is used, the tendency to cause damage becomes significant.

  On the other hand, in a construction machine such as a hydraulic excavator, the water separation device may receive a large vibration due to impact during excavation, traveling, and the like, and the malfunction of the notification device due to erroneous detection of the water level detection device may occur repeatedly. In such a case, when the water level of the water separation device actually reaches a predetermined height, the water level detection device operates correctly, and the notification device operates to notify the necessity of drainage work of the water separation device. There is a concern that the water separation device will no longer be drained due to the malfunction.

  In order to avoid such a problem, in Patent Document 1, the water level detection device is enabled only when it is determined that the construction machine is not operating, and erroneous detection of the water level detection device is prevented from occurring. However, in order to prevent false detection of such a water level detection device, the water level of the water separation device actually reaches a predetermined height, the water level detection device operates correctly, and the notification device notifies the necessity of drainage work. However, the seriousness that some operators may cause fatal damage to injectors, fuel systems, etc. due to the outflow of water stored in the water separator (this is simply referred to as “water separator” in this specification). It is unclear whether or not the drainage operation will be performed immediately without recognizing the seriousness of the outflow of the water stored in the system, and it is not mandatory from the viewpoint of engine protection.

  In Patent Document 2, when the water level detection device detects that the water level of the water separation device has reached a predetermined height and the drainage operation is not performed, the engine is automatically operated after a predetermined time has elapsed. By reducing the rotation speed, the operator is made aware of the seriousness regarding the outflow of the water stored in the water separation device. However, for example, for operators who use construction machines only at medium and low speeds, there is a possibility of continuing work without noticing that the engine speed is decreasing. From the viewpoint of engine protection, it is not compulsory.

  It is an object of the present invention to detect a water level sensor erroneously when a water separator is subjected to a large vibration due to an impact during excavation or traveling in a construction machine having a water separator and a water level sensor for separating water contained in fuel. Prevents the malfunction of the alarm device by the operator and makes the operator strongly aware of the seriousness of the outflow of the water stored in the water separator, and forces the operator to drain the water separator while minimizing the effect on workability. It is to provide a construction machine that can perform work.

  In order to achieve the above object, the present invention provides an engine, a fuel supply pipe for supplying fuel from a fuel tank to the engine, and a fuel supply pipe provided in the middle of the fuel supply pipe to separate and store water contained in the fuel. A water separation device, a water level sensor that continuously generates a water level arrival signal while the water level of water stored by the water separation device is higher than a predetermined level, and drainage of the water separation device based on the water level arrival signal A notification device that informs the operator that work is necessary, and a power ON position and an engine start position, and when operated to the power ON position, outputs a power ON key signal and is operated to the engine start position. A key switch that outputs a key signal for starting the engine, and the water level arrival signal and the key signal are input to control the operation of the notification device and the engine. When the key signal for turning on the power is input before starting the engine, the controller validates the input of the water level arrival signal from the water level sensor and reaches the water level. When the signal is input, the alarm device is operated, and a fail safe control including a speed limit control for reducing the engine speed and a fuel injection amount limit control for reducing the maximum output horsepower of the engine is performed. And

  In the present invention configured as described above, when the power ON key signal is input before the engine is started, the water separation device can be used for excavation, traveling, etc. by enabling the input of the water level arrival signal from the water level sensor. It is possible to prevent malfunction of the notification device due to erroneous detection of the water level sensor when receiving a large vibration due to impact.

  In addition, when the water level arrival signal is valid and the water level arrival signal is input, the notification device is operated, and the speed limit control for reducing the engine speed and the fuel injection amount for reducing the maximum output horsepower of the engine By performing fail-safe control including restriction control, it is possible to make the operator strongly aware of the seriousness regarding the outflow of water stored in the water separation device, and to force the operator to drain the water separation device. .

  Furthermore, if the water level arrival signal is not input at the time of the previous power ON key signal input and the water level of the water separator reaches a predetermined height before the engine is stopped, the power ON key for this time When the signal is input, the water level arrival signal is input from the water level sensor, and the rotation speed limit control and the fuel injection amount limit control are performed. Therefore, the operator separates the water only when the power ON key signal is input before the current engine start. It is only necessary to perform the drainage work of the apparatus, and the influence on workability can be minimized.

  According to the present invention, in a construction machine equipped with a water separator and a water level sensor for separating water contained in fuel, the water level sensor is erroneously detected when the water separator is subjected to a large vibration due to impact during excavation, traveling, etc. Prevents the malfunction of the alarm device by the operator and makes the operator strongly aware of the seriousness of the outflow of the water stored in the water separator, and forces the operator to drain the water separator while minimizing the effect on workability. It becomes possible to perform work.

1 is an external view of a hydraulic excavator that is a construction machine according to an embodiment of the present invention. It is a figure which shows the fuel supply system of an engine. It is a figure which shows the engine system provided with the engine protection function with which the construction machine (hydraulic excavator) of this Embodiment is equipped. It is a functional block diagram which shows the outline of the processing function of an engine controller. 4 is a flowchart showing details of a processing function of the engine controller 40. 4 is a flowchart showing details of a processing function of the engine controller 40. It is a figure which shows the change of the rotation speed and output torque characteristic of an engine at the time of performing rotation speed fall control and fuel injection amount restriction | limiting control.

  Hereinafter, a construction machine according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an external appearance of a hydraulic excavator that is a construction machine according to an embodiment of the present invention.

  In FIG. 1, the hydraulic excavator includes a lower traveling body 101, an upper swing body 109, and a swing-type front work machine 104. The front work machine 104 includes a boom 104a, an arm 104b, and a bucket 104c. The upper turning body 109 can turn with respect to the lower traveling body 101 by a turning motor 3c. A swing post 103 is attached to a front portion of the upper swing body 109, and a front work machine 104 is attached to the swing post 103 so as to be movable up and down. The swing post 103 can be rotated in the horizontal direction with respect to the upper swing body 109 by expansion and contraction of the swing cylinder 3e. The boom 104a, the arm 104b, and the bucket 104c of the front work machine 104 are the boom cylinder 3a, the arm cylinder 3b, and the bucket cylinder. It can be turned up and down by 3d expansion and contraction. A blade 106 that moves up and down by expansion and contraction of the blade cylinder 3h is attached to the central frame of the lower traveling body 102. The lower traveling body 101 travels by driving the left and right crawler belts 101a and 101b (only the left side is shown in FIG. 1) by the rotation of the traveling motors 3f and 3g.

  The upper swing body 109 is provided with a canopy-type driver's cab 108. In the driver's cab 108, a driver's seat 121, left / right operation devices 122 and 123 for front / turn (only the left side is shown in FIG. 1), and for driving Operating devices 124a and 124b (only the left side is shown in FIG. 1), a swing operating device and a blade operating device (not shown), a gate lock lever 125, and the like.

  An engine room is formed behind the driver's seat 121 of the upper swing body 109, and an engine 1 and a starter 2 for starting the engine 1 are arranged in the engine room.

  FIG. 2 is a diagram showing a fuel supply system of the engine 1.

  In FIG. 2, the fuel supply system of the engine 1 is provided in the middle of the fuel tank 4, the fuel supply pipe 5 that supplies fuel from the fuel tank 4 to the engine 1, and the fuel supply pipe 5. It has a water separation device 7 for separating and storing. The fuel tank 4 is disposed in the right storage space of the driver seat 121 of the upper swing body 109, and the water separator 7 is disposed, for example, near the fuel tank 4 in the right storage space.

  The water separator 7 includes a tank 7a for storing the separated water and a cock 7b provided at the bottom of the tank 7a for discharging the water stored in the tank 7a. The operator opens the cock 7b. Thus, water can be discharged to the outside.

  The water separation device 7 operates when the water level separated and stored by the water separation device 7 reaches a predetermined height, and the water level arrival signal ( A water level sensor 10 that continuously generates an electrical signal) is provided.

  The water level sensor 10 has a specific gravity larger than that of the fuel and smaller than that of the water. The float 10a floats on the boundary surface between the fuel and water in the water separator 7 and a guide 10b that guides the float 10a in the vertical direction. And a stopper 10c that sets an upper limit for the upward movement of the float 10a guided by the guide 10b, and when the water level in the water separator 7 reaches a predetermined height, And an output device 11 that continuously generates a water level arrival signal while the water level is above a predetermined height.

  The output device 11 is provided inside the guide 10b, for example, and a reed switch 11a in which two metal plates are arranged at the predetermined height positions with a predetermined interval, and a magnet embedded in the float 10a. 11b.

  As the water separator 7 separates the water contained in the fuel and stores it in the tank 7a, the amount of water in the tank 7a of the water separator 7 increases. When the water level reaches a predetermined height, the magnet 11b inside the float 10a floating on the boundary surface between the fuel and water approaches one of the two metal plates of the reed switch 11a, and this metal plate becomes magnetic. Therefore, the metal plates are attracted to each other. Thereby, both metal plates contact each other and are conducted. The water level sensor 10 generates an electric signal that flows at this time, that is, a water level arrival signal, and transmits the signal to the engine controller 40 (FIG. 3). Further, as long as the water level is at a predetermined height or higher, the water level sensor 10 continues to generate a water level arrival signal.

  FIG. 3 is a diagram showing an engine system having an engine protection function provided in the construction machine (hydraulic excavator) according to the present embodiment.

  3, the engine system in the present embodiment includes an engine control dial 20, a vehicle body monitor 22, a key switch 24, a starter relay 26, a battery (power supply device) 28, a vehicle body controller 30, and an engine controller 40. And.

  The engine control dial 20, the vehicle body monitor 22, and the key switch 24 are disposed at appropriate positions in the cab 108 of the upper swing body 109, and the battery 28, the vehicle body controller 30, and the engine controller 40 are arranged on the driver seat 121 of the upper swing body 109. It is located away from the engine room such as the lower side.

  The engine control dial 20 outputs an instruction signal for instructing the target rotational speed of the engine 1 by the operation of the operator.

  The vehicle body monitor 22 displays various information including the operating state of the engine and the remaining amount of fuel in the fuel tank. The vehicle body monitor 22 discharges water in the water separation device 7 when a water level arrival signal of the water level sensor 10 is generated and a notification signal (described later) is input from the engine controller 40 via the vehicle body controller 30. Display a drainage notice prompting That is, the vehicle body monitor 22 has a role as a notification device that notifies the operator that the water separation device 7 needs to be drained based on the water level arrival signal of the water level sensor 10.

  The key switch 24 has a plurality of key positions including an OFF position, a power ON position, and an engine start position. When the key switch 24 is operated to the power ON position, it outputs a power ON key signal and is operated to the engine start position. Sometimes the engine start key signal is output. The starter relay 26 is disposed between the key switch 24 of the power supply system and the starter 2 of the engine 1. When the key switch 24 is in the OFF position, the battery 28 is not connected to any contact of the key switch 24, and the power supply of the electrical components including the engine control dial 20, the vehicle body monitor 22, the vehicle body controller 30, and the engine controller 40 is OFF. When the operator inserts an engine key into the key switch 24 and the key switch 24 is operated from the OFF position to the power ON position, the contact B is connected to the battery 28 (energized), and the power is turned ON. When the key switch 24 is further operated from the power ON position to the engine start position, the contact C is connected to the battery 28 (energized). At this time, if the contact point 76a of the starter relay 76 is closed and energized, the starter 2 is driven and the engine 1 is started. Opening and closing of the contact point 76a of the starter relay 76 is controlled by the engine controller 40 (described later).

  The vehicle body controller 30 is electrically connected to the engine control dial 20 and the vehicle body monitor 22 and is electrically connected to the engine controller 40. The vehicle body controller 30 receives an instruction signal from the engine control dial 20, generates a set rotational speed signal based on the instruction signal (target rotational speed), and outputs the set rotational speed signal to the engine controller 40. When the vehicle controller 30 receives a notification signal (described later) from the engine controller 40, the vehicle body controller 30 transmits the notification signal to the vehicle body monitor 22.

  The engine controller 40 is electrically connected to the electronic governor (not shown) of the engine 1, the water level sensor 10, the key switch 24, and the starter relay 26, and from the water level arrival signal from the water level sensor 10 and the key switch 24. The key signal is input to control the operation of the vehicle body monitor 22 which is a notification device and the engine 1.

  The engine controller 40 performs the following control.

  First, when a power ON key signal is input from the key switch 24 before the engine 1 is started, the engine controller 40 validates the water level arrival signal input from the water level sensor 10 only immediately after the power ON key signal is input. When the water level arrival signal is input, the vehicle body monitor 22 (notification device) is operated, and the rotational speed limit control for reducing the rotational speed of the engine 1 and the fuel injection amount limiting control for reducing the maximum output horsepower of the engine 1 Fail-safe control including

  In addition, when a water level arrival signal is input, the engine controller 40 performs engine stop control for stopping the engine 1 when a predetermined time has elapsed after starting the fail-safe control.

  The engine controller 40 stores the presence / absence of a water level arrival signal in the storage device 40d (see FIG. 4) every time a power ON key signal is input, and when the previous power ON key signal is input. When it is determined that the water level arrival signal has been input both at the time of the power ON key signal input this time, engine start disable control is performed so that the engine 1 cannot be started.

  Further, the engine controller 40 cuts off the contact of the starter relay 26 when a key signal for power ON is input, and the water level is detected both when the key signal for the previous power ON and the key signal for the current power ON are input. When it is determined that the arrival signal has been input, the starter relay contact is kept disconnected and the engine start disable control is performed.

  FIG. 4 is a functional block diagram showing an outline of processing functions of the engine controller 40. The engine controller 40 includes an engine control unit 40a, a signal input control unit 40b, functions of the notification control unit 40c, and a storage device 40d.

  5A and 5B are flowcharts showing details of processing functions of the engine controller 40.

  5A, first, when an operator inserts an engine key into the key switch 24 and operates it to the power ON position, a key signal for power ON is output from the key switch 24 to the engine controller 40, and the engine controller 40a of the engine controller 40 The signal input control unit 40b receives the power ON key signal (step S100). When the key signal for turning on the power is input, the engine control unit 40a cuts off the contact 26a of the starter relay 26 and disables the engine 1 from starting (step S110). When the key signal for turning on the power is input, the signal input control unit 40b validates the input of the water level arrival signal from the water level sensor 10 (step S120). That is, the signal input control unit 40b opens the contact when the power ON key signal is not input, invalidates (impossible) the input of the water level arrival signal, and the contact when the power ON key signal is input. It functions as switch means that closes and allows the input of a water level arrival signal. As a result, when the water level sensor 10 generates a water level arrival signal when the power ON key signal is input, the water level arrival signal can be input to the engine control unit 40a and the notification control unit 40c.

  Next, the engine control unit 40a determines whether or not a water level arrival signal has been input at the time of the previous power-on key signal input and the current power-on key signal input (steps S130, S140, S300). ).

  If it is determined in steps S130 and S140 that the water level arrival signal has not been input either when the previous power ON key signal is input or when the current power ON key signal is input, the previous power ON key This is a case where the water level of the water separation device 7 has not reached a predetermined height after the signal is input, and the engine control unit 40a closes the contact 26a of the starter relay 26 and energizes it, thereby enabling the engine 1 to start. (Step S150). Whether or not the water level arrival signal is input at the time of the previous power ON key signal input is determined by storing the presence or absence of the water level arrival signal in the storage device 40d each time the power ON key signal is input from the key switch 24. In addition, the determination result stored is used. Further, in this state, when the operator operates the key switch 24 to the engine start position, electric power is supplied from the battery 28 to the starter 2, the starter 2 is driven, and the engine 1 is started.

  Next, the signal input control unit 40b operates the key switch 24 to the engine start position to determine whether or not an engine start key signal has been input (step S160), and the engine start key signal has been input. If it determines, the process which invalidates the input of a water level arrival signal will be performed (step S170). As a result, when the construction machine is subsequently operated, the vehicle body monitor 22 which is a notification device due to a false detection by the water level sensor 10 when the water separation device receives a large vibration due to impact due to excavation, traveling, etc. Incorrect control can be prevented.

  Next, in step S130, it is determined that the water level arrival signal has not been input when the previous power ON key signal was input. In step S140, the water level arrival signal was input when the current power ON key signal was input. When the determination is made, it is a case where the water level of the water separation device 7 has reached a predetermined height during operation of the construction machine after the previous power-on key signal has been input, and the notification control unit 40c detects the vehicle body monitor 22 (notification device). ) To notify the operator that the water separator 7 needs to be drained (step S200). Next, the engine control unit 40a closes the contact 26a of the starter relay 26 and energizes it, thereby enabling the engine 1 to start (step S210). In this state, when the operator operates the key switch 24 to the engine start position, electric power is supplied from the battery 28 to the starter 2, the starter 2 is driven, and the engine 1 is started.

  The signal input controller 40b operates the key switch 24 to the engine start position to determine whether or not an engine start key signal has been input (step S220), and the engine start key signal has been input. If it determines, the process which invalidates the input of a water level arrival signal will be performed (step S230). Accordingly, as in the case of step S170, when the construction machine is subsequently operated, the vehicle body monitor 22 which is a notification device due to erroneous detection of the water level sensor 10 when the water separator is subjected to large vibrations due to impact due to excavation, traveling, etc. It is possible to prevent erroneous notification and erroneous control of the engine 1.

  Next, the engine control unit 40a performs fail-safe control including rotation speed limit control for reducing the rotation speed of the engine 1 and fuel injection amount restriction control for reducing the maximum output horsepower of the engine 1 (step S240).

  The engine speed limit control is control for reducing the set engine speed of the engine 1 to be lower than the rated engine speed of the engine 1 (for example, 2000 rpm), and the engine control unit 40a controls the engine that is output to the electronic governor of the engine. Engine control in which the set rotational speed of the signal is changed from the target rotational speed indicated by the engine control dial 20 to an intermediate rotational speed (for example, 1500 rpm) lower than the rated rotational speed of the engine 1, and the rotational speed is set as the set rotational speed. The speed limit control is performed by outputting a signal to the electronic governor of the engine 1.

  The fuel injection amount restriction control is control for reducing the maximum fuel injection amount of the electronic governor from the rated maximum fuel injection amount and reducing the output horsepower of the engine 1 by, for example, about 15% from the rated horsepower of the engine 1. For example, the engine control unit 40a performs fuel injection amount restriction control by performing a process of restricting the maximum fuel injection amount when calculating the fuel injection amount from the target rotational speed.

  Next, the engine control unit 40a determines whether or not a predetermined time has elapsed after starting the rotation speed limitation control and the fuel injection amount limitation control (step S250), and stops the engine 1 when the predetermined time has elapsed. Take control. The predetermined time is, for example, 2 hours. The engine stop control can be performed by, for example, turning off an engine control signal output to the electronic governor to stop fuel injection.

  After starting the rotation speed limiting control and the fuel injection amount limiting control in this way, if the operator still stops the engine and does not drain the water separator, the engine is forcibly stopped and the hydraulic excavator Is disabled, and the operator is forced to perform drainage work.

  Next, in step S130, it was determined that the water level arrival signal was input when the previous power ON key signal was input. However, in step 300, the water level arrival signal was not input when the current power ON key signal was input. When the determination is made, it is a case where the operator has performed the drainage operation of the water separation device 7 during the operation of the construction machine after the previous power-on key signal is input, and the engine control unit 40a and the signal input control unit 40b perform step 150. , S160 and S170 are performed. That is, the engine control unit 30a enables the engine 1 to be started (step S310), and after the key signal for starting the engine is input to the signal input control unit 30b, the process of invalidating the input of the water level arrival signal is performed (step S310). S320, S330). In this state, when the operator operates the key switch 24 to the engine start position, electric power is supplied from the battery 28 to the starter 2, the starter 2 is driven, and the engine 1 is started. Further, in step S330, by performing the process of invalidating (impossible) the input of the water level arrival signal, as in step S170, the water separator is impacted by excavation, traveling, etc. during the subsequent operation of the construction machine. It is possible to prevent erroneous notification of the vehicle body monitor 22 which is a notification device due to erroneous detection of the water level sensor 10 when receiving large vibrations and erroneous control of the engine 1.

  On the other hand, in step S130, it is determined that the water level arrival signal has been input when the previous power ON key signal was input, and in step S300, it was determined that the water level arrival signal was also input when the current power ON key signal was input. When the previous power ON key signal is input, the necessity of drainage work is notified in step S200, the engine speed limit control and the fuel injection amount control are performed in step S240, and the engine stop control is performed in step S260. Nevertheless, this is a case where the operator has not performed the drainage operation of the water separator 7. In this case, the notification control unit 40c operates the vehicle body monitor 22 (notification device) to notify the operator again that the water separator 7 needs to be drained (step S400), and then contacts the starter relay 26. Even if the operator keeps the switch 26a shut off and the key switch 24 is operated to the engine start position, the engine 1 is controlled so that the engine 1 is not started. Further, the signal input control unit 30b performs a process of invalidating the input of the water level arrival signal after inputting the key signal for starting the engine (steps S410 and S420).

  FIG. 6 is a diagram showing changes in the rotational speed and output torque characteristics of the engine 1 when the rotational speed restriction control and the fuel injection amount restriction control are performed. The horizontal axis is the rotational speed of the engine 1, and the vertical axis is the output torque of the engine 1. Symbol A is an output torque characteristic of the engine 1 at the rated rotation speed when the rotation speed limitation control and the fuel injection amount limitation control are not performed, and symbol B indicates the rotation speed limitation control and the fuel injection amount limitation control. It is the output torque characteristic of the engine 1 when performing.

  The output torque characteristic A of the engine 1 is composed of a regulation characteristic Tra until the fuel injection amount of the electronic governor increases from the minimum to the maximum, and a full load characteristic Tfa when the fuel injection amount of the electronic governor reaches the maximum. ing. In the illustrated example, the regulation characteristic Tra is an example of an isochronous characteristic in which the engine speed is controlled to be constant regardless of increase or decrease in the fuel injection amount of the electronic governor. The regulation characteristic Tra may be a droop characteristic in which the engine speed decreases as the fuel injection amount of the electronic governor increases. The full load characteristic Tfa has a characteristic that when the fuel injection amount is maximum, the output torque increases as the output rotational speed of the engine 1 decreases, and becomes maximum torque at a point E lower than the intermediate rotational speed. Thus, even after the fuel injection amount of the electronic governor is maximized, the output torque is increased in accordance with the decrease in the output speed due to the increase in the engine load, and the engine stall is less likely to occur.

  When the rotation speed limit control and the fuel injection amount limit control are performed, the output torque characteristic of the engine 1 changes as indicated by B. That is, the regulation characteristic is changed from Tra to Trb by the rotational speed restriction control, and the full load characteristic is changed from Tfa to Tfb by the fuel injection amount restriction control.

  The rotational speed limit control is control for reducing the set rotational speed of the engine 1 below the rated rotational speed (for example, 2000 rpm), and the set rotational speed is, for example, the rotation at the maximum torque point E from the rated rotational speed as indicated by an arrow C. The rotational speed is reduced to about 200 rpm higher than the number (for example, 1500 rpm).

  Here, when only the rotational speed limitation control is performed, the fuel injection amount of the electronic governor becomes the maximum at the torque point G on the full load characteristic Tfa, whereas the fuel injection amount limitation control is performed and the maximum of the electronic governor is controlled. When the fuel injection amount is limited, the torque point that is the maximum fuel injection amount decreases from the G point to, for example, the H point. Therefore, the full load characteristic changes from Tfa to Tfb, and the maximum output horsepower (product of output torque and rotation speed) of the engine 1 at the maximum fuel injection amount also decreases. The limit amount of the fuel injection amount is set so that, for example, the maximum output horsepower is reduced by about 15% from the rating.

  In this way, not only the maximum rotation speed of the engine 1 but also the maximum output horsepower of the engine 1 is reduced by the fuel injection amount restriction control, so that only the drive speed of the actuators such as the boom cylinder 3a, arm cylinder 3b, bucket cylinder 3d, etc. In addition, since the driving force is also reduced, workability is significantly reduced, and the operator can be surely noticed that the engine performance is reduced. Thereby, it is possible to make the operator strongly recognize the seriousness regarding the outflow of the water stored in the water separator 7, forcibly stop the engine, and allow the water separator 7 to perform the drainage work.

  According to the present embodiment configured as described above, the following effects can be obtained.

  1. After a power ON key signal is input from the key switch 24 in step S100, the input of the water level arrival signal from the water level sensor 10 is validated in step S120, and the engine start key signal is output in steps S160, S220, S320, and S410. After determining that it has been input, processing for invalidating the input of the water level arrival signal is performed in steps S170, S230, S330, and S420. In this way, the input of the water level arrival signal from the water level sensor 10 is made effective only immediately after the input of the power ON key signal before the engine 1 is started. Thus, it is possible to prevent erroneous notification of the vehicle body monitor 22 (notification device) and erroneous control of the engine 1 due to erroneous detection of the water level sensor 10 when large vibrations are received.

  2. In steps S120, S130, S140, S200, and S240, the input of the water level arrival signal is validated, and when the water level arrival signal is input, the vehicle body monitor 22 (notification device) is operated and the rotational speed of the engine 1 is decreased. Fail-safe control including rotational speed limiting control and fuel injection amount limiting control for reducing the maximum output horsepower of the engine 1 is performed. This makes it possible for the operator to strongly recognize the seriousness regarding the outflow of the water stored in the water separation device, and to force the operator to perform the drainage operation of the water separation device.

  3. If the water level arrival signal is not input at the time of the previous power ON key signal input at step S130 and the water level of the water separation device 7 reaches a predetermined height before the engine is stopped thereafter, at step 140 this time When a power ON key signal is input, a water level arrival signal is input from the water level sensor 10, and in steps S240 to S260, rotation speed limiting control, fuel injection amount limiting control, and engine stop control are performed. As a result, the operator only has to perform the drainage work of the water separator 7 only when the power ON key signal is input before the engine is started this time, and the influence on workability can be minimized.

  4). When the water level arrival signal is input, the engine controller 40 not only performs the rotation speed limit control and the fuel injection amount limit control, but also stops the engine 1 when a predetermined time has elapsed in steps S250 and S260. I do. As a result, the operator is forced to perform the drainage operation of the water separation device 7, and the operator can be forced to perform the drainage operation of the water separation device 7.

  5). When the engine controller 40 determines in steps S130 and S300 that the water level arrival signal has been input both when the power-on key signal was input last time and when the power-on key signal was input this time, the engine 1 cannot be started. The engine start disable control is performed. As a result, the operator cannot operate the construction machine unless the water separator 7 is drained, so that the operator can reliably drain the water separator 7.

  6). The engine controller 40 shuts off the contact of the starter relay 26 when a power ON key signal is input in step S110, and in steps S130 and S300, the previous power ON key signal input and the current power ON When it is determined that the water level arrival signal has been input both when the key signal is input, the engine start disable control is performed by keeping the starter relay contact disconnected. This also enables the engine stop control in step S260 to be performed with a simple configuration using the existing starter relay 26.

~ Others ~
It should be noted that the above embodiment can be variously modified. Several modifications will be described below.

  1. In the above embodiment, the engine controller 40 performs engine stop control for stopping the engine 1 after a predetermined time has elapsed in steps S250 and S260 when the water level arrival signal is input. Only the restriction control and the fuel injection amount restriction control may be performed. Even in such a case, not only the driving speed of the actuator but also the driving force is reduced, so that the workability is remarkably reduced, and the operator can be surely noticed that the engine performance is reduced as compared with the prior art.

  2. In the above embodiment, the engine controller 40 determines whether or not a water level arrival signal is input every time a power ON key signal is input in step S120, and the previous power ON key signal in steps S130 and S300. When it is determined that the water level arrival signal has been input both at the time of input and at the time of the power ON key signal input, the engine start disable control is performed to disable the engine start, but this engine start disable control is omitted. be able to. However, by providing this engine start disable control, the operator cannot operate the construction machine unless the water separator 7 is drained as described above, and the operator can reliably drain the water separator 7. From the viewpoint of engine protection.

  3. In the above-described embodiment, the case where the rotation speed limit control and the fuel injection amount limit control are started simultaneously in the fail-safe control in step S240 has been described. However, after the rotation speed limit control is started, the fuel injection is performed when a predetermined time elapses. The amount restriction control may be performed. The predetermined time in this case is, for example, 1 hour 45 minutes, and the duration of the subsequent fuel injection amount control is, for example, 15 minutes.

  4). In the above embodiment, the engine controller 40 is provided with the functions of the engine control unit 40a, the signal input control unit 40b, and the notification control unit 40c, and the storage device 40d. The controller 30 may be provided. For example, when all of the engine control unit 40a, the signal input control unit 40b, the notification control unit 40c, and the storage device 40d are provided in the vehicle body controller 30, the water level arrival signal from the water level sensor 10 is input to the vehicle body controller 30, and the key The key signal from the switch 24 is input to the vehicle body controller 30 via the engine controller 40, for example. The notification control unit 40c of the vehicle body controller 30 directly outputs a notification signal to the vehicle body monitor 22 (notification device), and the engine control unit 40a transmits the engine control signal and the control signal of the starter relay 26 to the engine controller 40. Control of the engine 1 and control of opening and closing the contact 26a of the starter relay 26 may be performed via 40.

  5). In the above embodiment, the case where the construction machine is a hydraulic excavator has been described. However, if the construction machine includes a water separation device and a water level sensor, a construction machine other than the hydraulic excavator (for example, a wheel loader, a hydraulic crane, a wheeled excavator) is used. Etc.), and the same effect can be obtained in this case.

DESCRIPTION OF SYMBOLS 1 Engine 2 Starter 4 Fuel tank 5 Fuel supply piping 7 Water separator 10 Water level sensor 20 Engine control dial 22 Body monitor (notification device)
24 key switch 26 starter relay 28 battery 30 vehicle body controller (controller)
40 Engine controller (controller)
40a Engine control unit 40b Signal input control unit 40c Notification control unit 40d Storage device

Claims (4)

Engine,
A fuel supply pipe for supplying fuel from a fuel tank to the engine;
A water separator provided in the middle of the fuel supply pipe for separating and storing water contained in the fuel;
A water level sensor that continuously generates a water level arrival signal while the water level of the water stored by the water separator is above a predetermined height;
A notification device for notifying an operator that the water separation device needs to be drained based on the water level arrival signal;
A key switch that has a power ON position and an engine start position, outputs a power ON key signal when operated to the power ON position, and outputs an engine start key signal when operated to the engine start position;
In the construction machine including the water level arrival signal and the key signal, the operation of the notification device and a controller for controlling the engine,
The controller is
When the power ON key signal is input before the engine is started, the input of the water level arrival signal from the water level sensor is validated, and when the water level arrival signal is input, the notification device is operated. In addition, the construction machine performs fail-safe control including rotational speed limiting control for reducing the rotational speed of the engine and fuel injection amount limiting control for reducing the maximum output horsepower of the engine. The construction machine according to claim 1,
The construction machine is characterized in that when the water level arrival signal is input, the controller performs engine stop control for stopping the engine when a predetermined time elapses after starting the fail-safe control. The construction machine according to claim 1,
The controller is
Whenever the power ON key signal is input, the presence / absence of the water level arrival signal is stored in a storage device, and the previous power ON key signal input and the current power ON key signal input are stored. A construction machine that performs engine start disable control that disables starting of the engine when it is determined that the water level arrival signal has been input in both. The construction machine according to claim 3,
A starter relay disposed between the key switch and the engine starter;
The controller cuts off the contact of the starter relay when the power ON key signal is input, and the controller turns on both the previous power ON key signal input and the current power ON key signal input. A construction machine characterized in that when it is determined that a water level arrival signal has been input, the starter relay contact is kept disconnected and the engine start disable control is performed.

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