JP2013160057A - Exhaust emission control device of construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of a construction machine capable of notifying a driver of an operation condition suitable for a present state when a residual quantity of a liquid reducing agent is reduced.SOLUTION: An exhaust emission control device of a construction machine purifies exhaust gas exhausted from a diesel engine 1 by injecting urea water stored in a urea water tank 23 into an exhaust passage 9, includes a urea water liquid level sensor 24 for detecting the residual quantity of the urea water stored in the urea water tank 23, displays a warning on a monitor 7 when the urea water becomes a predetermined residual quantity based on a detecting result of the urea water liquid level sensor 24, and displays the operation condition of the diesel engine 1 corresponding to the residual quantity of the urea water on the monitor 7 based on the detecting result of the urea water liquid level sensor 24.

Description

  The present invention relates to an exhaust gas purification apparatus for a construction machine, and more particularly to an exhaust gas purification apparatus for a construction machine that purifies exhaust gas using a liquid reducing agent.

  In recent years, construction equipment such as hydraulic excavators equipped with diesel engines has been equipped with exhaust gas purification devices in the exhaust system of diesel engines in order to comply with high-order exhaust gas regulations. Is released into the atmosphere through the NOx reduction catalyst provided in

  Conventionally, as this type of exhaust gas purifying apparatus, a selective reduction type NOx purifying apparatus using a liquid reducing agent (for example, urea aqueous solution) is often employed. However, an exhaust gas purification apparatus using a liquid reducing agent cannot perform exhaust gas purification processing when the liquid reducing agent is exhausted. In addition, since the engine can be operated even if the liquid reducing agent is used up, a large amount of NOx is discharged if the engine is operated in the state where the liquid reducing agent is used up.

  In order to avoid this, conventionally, when the remaining amount of the liquid reducing agent is reduced, this is detected, an alarm is issued, and the output of the engine is forcibly reduced (Patent Document 1).

JP 2002-371831 A

  However, the conventional exhaust gas purification apparatus is configured to forcibly reduce the engine output when the remaining amount of the liquid reducing agent decreases, regardless of the intention of the construction machine operator. There is a problem that it is impossible to carry out the work systematically by taking into consideration both the remaining amount of the agent and the work situation at the site.

  The present invention has been made in view of the above points, and provides an exhaust gas purification device for a construction machine capable of notifying a driver of operating conditions suitable for the current state when the remaining amount of liquid reducing agent is reduced. The purpose is to do.

From the first point of view, the above problem is
An exhaust gas purifying apparatus for a construction machine that purifies exhaust gas discharged from an engine by injecting a liquid reducing agent stored in a liquid reducing agent tank into an exhaust passage,
A remaining amount detecting device for detecting the remaining amount of the liquid reducing agent stored in the liquid reducing agent tank;
Based on the detection result of the remaining amount detection device, alarm display means for displaying an alarm on a display device when the liquid reducing agent reaches a predetermined remaining amount;
Exhaust gas purification for construction machinery, comprising: operating condition display means for displaying on the display device the operating condition of the engine corresponding to the remaining amount of the liquid reducing agent based on the detection result of the remaining amount detecting device. It can be solved by the device.

  According to the disclosed invention, it is possible to notify the driver of the engine operating conditions corresponding to the remaining amount of the liquid reducing agent, so that the driver can work in consideration of the displayed operating conditions and the on-site work conditions. Can proceed.

FIG. 1 is a configuration diagram of an exhaust gas purification apparatus for a construction machine according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a mode setting device. FIG. 3 is a flowchart showing an operation condition display process performed by the machine controller according to the embodiment of the present invention. FIG. 4 is a view showing a display example of operating conditions of the exhaust gas purifying apparatus for construction machinery according to the embodiment of the present invention (part 1). FIG. 5: is a figure which shows the example of a display of the operating conditions of the exhaust gas purification apparatus of the construction machine which is one Embodiment of this invention (the 2). FIG. 6 is a view showing a display example of operation conditions of the exhaust gas purifying apparatus for construction machinery according to the embodiment of the present invention (part 3). FIG. 7 is a view showing another display example of the operating conditions (No. 1). FIG. 8 is a diagram showing another display example of the operating conditions (part 2).

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows an exhaust gas purification apparatus for a construction machine according to an embodiment of the present invention. The exhaust gas purification apparatus 2 according to the present embodiment purifies exhaust gas discharged from a diesel engine 1 provided in a construction machine such as a hydraulic excavator.

  The diesel engine 1 is driven by being supplied with fuel from a fuel tank (not shown) by a high pressure pump, and directly injecting the high pressure fuel into a combustion chamber for combustion. The diesel engine 1 and the high-pressure pump are controlled by an engine control module 4 (hereinafter referred to as ECM).

  The exhaust gas from the diesel engine 1 passes through the turbocharger 8 and then flows into the exhaust passage 9 downstream thereof. After being purified by the exhaust gas purification device 2, the exhaust gas is discharged to the atmosphere.

  On the other hand, the intake air introduced from the air cleaner 10 into the intake passage 11 passes through the turbocharger 8 and the intercooler 13 and is supplied to the diesel engine 1.

  The exhaust passage 9 includes a particulate filter (DPF) 16 that collects particulates (PM) in the exhaust gas from the upstream side, and a selective reduction type NOx catalyst (SCR) 19 that reduces and removes NOx in the exhaust gas. Are provided in series.

  The selective reduction type NOx catalyst 19 continuously reduces and removes NOx in the exhaust gas when a liquid reducing agent (for example, urea or ammonia) is supplied. In this embodiment, urea water is used as a liquid reducing agent for ease of handling.

  A urea water injection valve 20 for supplying urea water to the selective reduction type NOx catalyst 19 is provided upstream of the selective reduction type NOx catalyst 19 in the exhaust passage 9. The urea water injection valve 20 is connected to a urea water tank 23 (liquid reducing agent tank) via a urea water supply line 21.

  The urea water supply line 21 is provided with a urea water supply pump 22. The urea water stored in the urea water tank 23 is supplied to the urea water injection valve 20 by the urea water supply pump 22 and is injected from the urea water injection valve 20 to the upstream position of the selective reduction type NOx catalyst 19 in the exhaust passage 9. The

  The urea water injected from the urea water injection valve 20 is supplied to the selective reduction type NOx catalyst 19. The supplied urea water is hydrolyzed in the selective reduction type NOx catalyst 19 to generate ammonia. This ammonia reduces the NOx contained in the exhaust gas in the selective reduction type NOx catalyst 19, thereby purifying the exhaust gas.

The first NO _X sensor 14 is disposed on the upstream side of the urea water injection valve 20. Further, the second NO _X sensor 15 is disposed on the downstream side of the selective reduction type NOx catalyst 19. The NO _X sensors 14 and 15 detect the NO _X concentration in the exhaust gas at the respective arrangement positions.

  A urea water level sensor 24 is disposed in the urea water tank 23. The urea water level sensor 24 is a liquid level sensor that detects the remaining amount of urea water in the urea water tank 23. In the present embodiment, the remaining amount signal A1 is displayed when the remaining amount of urea water in the urea water tank 23 reaches the position indicated by A1 (remaining position A1) in the figure, and the remaining amount of urea water is smaller than this. A remaining amount signal A2 is output when the position indicated by A2 (remaining amount position A2) is reached.

Each of the sensors 14, 15, 24, the urea water injection valve 20, and the urea water supply pump 22 are connected to the exhaust gas purification device controller 5. Urea water injection valve 20 and the urea water supply pump 22, based on the NOx concentration detected by the first and second of the NO _X sensor 14, the exhaust gas purifying apparatus controller 5 so that the injection amount of urea water is proper Be controlled.

  The exhaust gas purification device controller 5 is connected to an ECM 4 that controls the diesel engine 1 by communication means. The ECM 4 is connected to the machine controller 6 by communication means.

  The machine controller 6 controls a hydraulic pump that drives a boom, an arm, and the like, and various control valves that supply and stop supplying oil to a hydraulic system such as a boom cylinder and an arm cylinder. The machine controller 6 is connected to an engine control module (ECM) 4 and an exhaust gas purification device controller 5 via communication means.

  Therefore, various information on the exhaust gas purification device 2 included in the exhaust gas purification device controller 5 and various information on the diesel engine 1 included in the ECM 4 can be shared by the machine controller 6. The ECM 4, the exhaust gas purification device controller 5, and the machine controller 6 each include a CPU, a ROM, a RAM, an input / output port, a storage device, and the like.

  A monitor 7 (display device) and a mode setting device 18 (work mode setting means) are connected to the machine controller 6. On the monitor 7, an alarm and an operating condition display are displayed. The alarm and operation condition display will be described later for convenience of explanation.

  The mode setting device 18 is a device that switches the work mode of the construction machine. FIG. 2 shows the mode setting device 18 in an enlarged manner. The construction machine according to the present embodiment has a configuration in which the work mode can be switched to the three modes of the SP mode, the H mode, and the A mode by the mode setting device 18. The mode setting device 18 can perform mode switching by rotating the switch knob 18a and adjusting the instruction unit 18b to each display of SP, H, and A.

  The mode setting device 18 controls the rotational speed of the diesel engine 1 via the machine controller 6 and the ECM 4. The target engine speed in the SP mode is set to α rpm, the target engine speed in the H mode is set to β rpm, the target engine speed in the A mode is set to γ rpm, and each speed is set to satisfy α> β> γ. Has been.

  Therefore, the output of the diesel engine 1 becomes the highest output when the work mode is set to the SP mode by the mode setting device 18, and the engine output decreases in the order of the H mode and the A mode.

  Next, the operation of the exhaust gas purifying apparatus 2 configured as described above will be described with reference to FIG. FIG. 3 shows a control process executed by the machine controller 6. This control process is a routine process that is repeatedly executed every predetermined time.

  When the control process shown in FIG. 3 is started, first, the machine controller 6 determines whether or not the urea water level signal is output from the urea water level sensor 24 via the exhaust gas purification device controller 5 (step 10 in the figure). Step is abbreviated as S).

  The urea water level sensor 24 outputs a remaining amount signal A1 when the remaining amount of urea water in the urea water tank 23 reaches the remaining amount position A1, and a remaining amount signal A2 when the remaining amount of urea water becomes A2. Output to the machine controller 6. The machine controller 6 repeats the process of step 10 until the remaining amount signal A1 is output from the urea water level sensor 24.

  On the other hand, if it is determined in step 10 that the remaining amount signal is output from the urea water level sensor 24, the machine controller 6 warns the monitor 7 that the remaining amount of urea water in the urea water tank 23 has decreased. Is displayed (step 11).

  Subsequently, the machine controller 6 determines the type of the remaining amount signal output from the urea water level sensor 24 (step 12). As described above, the urea water level sensor 24 outputs the remaining amount signals A1 and A2 according to the remaining amount of urea water. If it is determined in step 12 that the remaining amount signal A1 is output from the urea water level sensor 24, the process proceeds to step 13, and the machine controller 6 detects the work mode currently set by the mode setting device 18. .

  Here, the state in which the urea water remaining amount of the urea water tank 23 is A1 is a state in which the engine output of the diesel engine 1 is to be reduced.

  Therefore, when it is determined in step 13 that the diesel engine 1 is currently in the SP mode, the machine controller 6 displays a message on the monitor 7 urging the driver to switch the work mode from the SP mode to the H mode or the A mode. (Step 14).

  FIG. 4 shows an example of a message displayed on the monitor 7 by the process of step 14. As shown in the figure, the message M11 from step 11 and the message M14 from step 14 are simultaneously displayed on the monitor 7. When the process of step 14 is completed, the current process is terminated, and the process returns to step 10 while the message M11 is displayed.

  On the other hand, if it is determined in step 13 that the current work mode is not the SP mode, the process returns to step 10. When returning from step 13 to step 10, only the message M11 in FIG. 4 is displayed on the monitor 7, and the message M14 is not displayed.

  If it is determined in step 12 that the remaining amount signal A2 is output from the urea water level sensor 24, the process proceeds to step 15. In step 15, it is determined whether or not the mode currently set by the mode setting device 18 is the SP mode.

  Here, the state in which the urea water remaining amount in the urea water tank 23 is A2 is a state in which the engine output of the diesel engine 1 is to be decreased more than when the urea water remaining amount is A1. .

  Therefore, if the SP mode is maintained in such a state, the remaining amount of urea water will be lost in a shorter time. Therefore, when it is determined in step 15 that the diesel engine 1 is currently in the SP mode, the machine controller 6 displays on the monitor 7 a message prompting the driver to switch the work mode from the SP mode to the A mode. (Step 16).

  FIG. 5 shows an example of a message displayed on the monitor 7 by the process of step 16. As shown in the figure, the message M11 from step 11 and the message M16 from step 16 are simultaneously displayed on the monitor 7. When the process of step 16 is completed, the current process is terminated, and the process returns to step 10 with the message M11 displayed.

  On the other hand, if it is determined in step 15 that the current work mode is not the SP mode, the process proceeds to step 17 and the machine controller 6 determines whether or not the current work mode is the H mode.

  If it is determined in step 17 that the current mode is the H mode, the machine controller 6 displays a message on the monitor 7 prompting the driver to switch the work mode from the H mode to the A mode (step 18).

  FIG. 6 shows an example of a message displayed on the monitor 7 by the process of step 18. As shown in the figure, the message M11 from step 11 and the message M18 from step 18 are simultaneously displayed on the monitor 7. When the process of step 16 is completed, the current process is terminated, and the process returns to step 10 with the message M11 displayed.

  On the other hand, if it is determined in step 17 that the work mode is not the H mode, in other words, the work mode is already in the A mode, the process returns to step 10. When returning from step 7 to step 10, the monitor 7 displays only the message M11.

  According to the above-described embodiment, the operator of the construction machine corresponds to the remaining amount of urea water (appropriate) together with an alarm (message M11) indicating that the remaining amount of urea water has decreased by looking at the monitor 7. ) The operating conditions of the diesel engine 1 can be known. This operating condition is a work mode set by the mode setting device 18 in this embodiment.

  Therefore, for example, when the message M14 shown in FIG. 4 is displayed on the monitor 7, the driver changes the work mode from the SP mode to the H mode in order to suppress the usage amount of the urea water by looking at the monitor 7. It is clear that this is desirable. Similarly, for example, when the message M18 shown in FIG. 6 is displayed on the monitor 7, the driver looks at the monitor 7, and the work mode is changed from the H mode to the A mode in order to suppress the use amount of urea water. It turns out that it is desirable to change.

  However, the exhaust gas purification apparatus 2 according to the present embodiment does not forcibly reduce the engine output immediately when the urea water remaining amount in the urea water tank 23 becomes the urea water remaining amount A1 or the urea water remaining amount A2. The operation condition of the diesel engine 1 suitable for (corresponding to) the remaining amount of urea water is presented.

  The operation state of the construction machine changes depending on the progress of work, work schedule, work content, and the like. For example, if the current work requires high engine output but is completed in a short time, the amount of urea water used is small even if the engine output is set to the SP mode. However, even if the engine output is lowered, the amount of urea water increases when the work time of the work is long. As described above, the amount of urea water used varies depending on the above-described progress of work, work schedule, work contents, and the like.

  According to the exhaust gas purification apparatus 2 according to the present embodiment, when the driver displays an alarm in step 11 on the monitor 7, the driver can monitor the monitor 7 in addition to information such as the progress of work, work schedule, and work content. It is also possible to determine the operating condition of the construction machine that is most suitable for the current work in consideration of the operating condition (working mode) corresponding to the current urea water remaining amount displayed in FIG. Thereby, the construction machine can be operated according to the work site, and the degree of freedom of work using the construction machine can be increased.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments described above, and various modifications are possible within the scope of the gist of the present invention described in the claims. It can be modified and changed.

  For example, the operating conditions displayed on the monitor 7 are not limited to the messages shown in FIGS. 4 to 6, but may be messages prompting the engine speed to be lowered as shown in FIG. 7, or as shown in FIG. It may be a message that prompts the user to slow down the work speed.

  Further, in each of the above-described embodiments, a construction machine having a configuration in which the work mode can be set to the three modes of the SP mode, the H mode, and the A mode has been described as an example. There is a configuration that can set a low target rotational speed.

  In this mode setting device, a notch corresponding to the throttle opening is shown in order to set a target rotational speed equal to or lower than the A mode. Therefore, by rotating the switch knob 18a and aligning the instruction unit 18b with the notch, the target engine speed can be set to the speed corresponding to the notch.

  When the mode setting device having the above-described configuration is provided, a message that prompts the user to lower the notch may be displayed. As a display example at this time, a message such as “Please lower the throttle by 3 notches” is conceivable.

  The present invention can be widely applied to construction machines and work vehicles having an exhaust gas purification device using a liquid reducing agent.

1 Diesel engine 2 Exhaust gas purification device 4 Engine control module (ECM)
5 exhaust gas purification device controller 6 machine controller 7 monitor 9 exhaust passage 11 intake passage 16 particulate filter 18 mode setting switch 19 selective reduction type NOx catalyst 20 urea water injection valve 21 urea water supply line 22 urea water supply pump 23 urea water tank 24 Urea water level sensor

Claims (3)

An exhaust gas purifying apparatus for a construction machine that purifies exhaust gas discharged from an engine by injecting a liquid reducing agent stored in a liquid reducing agent tank into an exhaust passage,
A remaining amount detecting device for detecting the remaining amount of the liquid reducing agent stored in the liquid reducing agent tank;
Based on the detection result of the remaining amount detection device, alarm display means for displaying an alarm on a display device when the liquid reducing agent reaches a predetermined remaining amount;
Exhaust gas purification for construction machinery, comprising: operating condition display means for displaying on the display device the operating condition of the engine corresponding to the remaining amount of the liquid reducing agent based on the detection result of the remaining amount detecting device. apparatus. The construction machine has a plurality of work modes variable by work mode setting means,
The exhaust gas purification apparatus for a construction machine according to claim 1, wherein the operation condition display means displays a work mode corresponding to the remaining amount of the liquid reducing agent as the operation condition.   The exhaust gas purifying device for a construction machine according to claim 1 or 2, wherein the remaining amount detecting device is a liquid level sensor that detects the remaining amount of the liquid reducing agent in the liquid reducing agent tank.

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