JP2010223158A - Exhaust gas treating device of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the waste of fuel by surely performing filter regeneration operation by arranging a combustion condition by automatically raising a temperature when a filter inside temperature is a preset value or lower, when starting the filter regeneration operation. <P>SOLUTION: On the assumption of a forced combustion system for burning a toxic substance by supplying the fuel in an exhaust gas filter 15, the filter inside temperature is detected by a temperature sensor 23, and when starting filter regeneration by the operation of a regeneration starting switch 22, when the filter inside temperature is the preset value or lower suitable for combustion, a relief valve 10 is operated by closing an unloading passage opening/closing valve 12, and thereby, the fuel is supplied after automatically performing temperature rise operation for increasing an engine load by increasing pump pressure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an exhaust gas treatment apparatus for removing harmful substances in exhaust gas from an engine with an exhaust gas filter in a construction machine such as a hydraulic excavator and regenerating the filter by incinerating harmful substances accumulated on the filter in a timely manner. It is.

  Conventionally, exhaust gas discharged from diesel engines in construction machinery is introduced into an exhaust gas filter (DPF: Diesel Particulate Filter) to remove harmful substances, especially PM (Particulate Matter) such as soot, and purify it. A processing device is used (see Patent Documents 1 and 2).

  In this type of exhaust gas purification device, as shown in Patent Document 2, in order to prevent clogging of the exhaust gas filter and keep the purification action constant, the PM deposited on the exhaust gas filter is burned and removed in a timely manner. A filter regeneration (also referred to as self-regeneration) operation is performed.

  As this filter regeneration method, a forced combustion method is known in which harmful substances are forcibly burned by supplying engine fuel into the exhaust gas filter.

Japanese Patent No. 3073380 JP 2005-299436 A

  However, in the known technology, fuel is supplied into the filter regardless of the actual filter temperature when the filter is regenerated by the forced combustion method, so that the temperature in the filter rises to a temperature suitable for combustion (hereinafter referred to as the combustion temperature). There was a possibility that the fuel could be supplied in a state that was not. In this case, the filter cannot be regenerated and fuel is wasted.

  Therefore, the present invention automatically adjusts the combustion conditions by raising the temperature automatically when the filter internal temperature is equal to or lower than the set value (the combustion temperature) at the start of the filter regeneration operation. It is an object of the present invention to provide an exhaust gas treatment apparatus for a construction machine that can prevent waste.

  The invention of claim 1 is directed to an engine, an exhaust gas filter that removes harmful substances in the exhaust gas emitted from the engine, a regeneration start switch that is operated by an operator to instruct the start of regeneration of the exhaust gas filter, and the exhaust gas filter. A fuel supply means for supplying fuel; a deposition amount detection means for detecting a deposition amount of harmful substances in the exhaust gas filter; a temperature detection means for detecting a temperature in the exhaust gas filter; and a control means. Is that when the regeneration start switch is operated, the accumulation amount detected by the accumulation amount detection means is not less than a set value as a value that requires regeneration, and the exhaust gas filter temperature detected by the temperature detection means On the condition that the value is equal to or greater than a set value suitable for combustion of hazardous substances, the exhaust gas flow is controlled by the fuel supply means. Fuel is supplied to the filter and a filter regeneration operation is performed to burn the harmful substances accumulated on the filter. When the exhaust gas filter temperature is lower than the set value, a temperature increase operation is performed to increase the filter temperature to the set value or higher. After having performed, it is comprised so that reproduction | regeneration operation may be started.

  According to a second aspect of the present invention, in the configuration of the first aspect, the discharge line of the hydraulic pump driven by the engine is provided with a relief line having a relief valve, and excess oil is discharged from the discharge oil of the hydraulic pump. And an unload passage blocking means for closing the passage is provided in the unload passage, and the control means performs the unload passage blocking means as the temperature increasing operation by the unload passage blocking means. The relief passage is configured to shut off the load passage.

  According to a third aspect of the present invention, in the configuration of the first or second aspect of the present invention, an engine rotational speed detecting means for detecting the rotational speed of the engine is provided, and the control means increases the engine rotational speed as a temperature raising operation. It is configured.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the engine further includes an engine speed detecting means for detecting the engine speed, and the control means sets the engine speed during the regeneration operation. It is configured to be limited to a range.

  According to a fifth aspect of the present invention, in the configuration of any one of the first to fourth aspects, a variable displacement hydraulic pump is used as the hydraulic pump driven by the engine, and the control means is configured to perform the hydraulic pump during a regeneration operation. The capacity is limited to a set value or less.

  According to a sixth aspect of the present invention, in the configuration of any one of the first to fifth aspects, a hydraulic pump driven by the engine, a control valve for controlling an operation of a hydraulic actuator using the hydraulic pump as a hydraulic source, and the control An operation means for operating the valve; and an operation stop means for stopping the operation of the control valve by the operation of the operation means. The control means is configured to stop the operation of the control valve by the operation stop means during the regeneration operation. It is composed of.

According to a seventh aspect of the present invention, in the configuration of any one of the first to sixth aspects, a hydraulic pump driven by the engine, a control valve for controlling an operation of a hydraulic actuator using the hydraulic pump as a hydraulic source, and the control Operation means for operating the valve, operation detection means for detecting whether or not the operation means is operated, pump pressure detection means for detecting the discharge pressure of the hydraulic pump, and engine speed detection for detecting the engine speed And the control means during the reproduction operation,
(I) When the operation means is operated,
(II) When the fluctuation range of the discharge pressure of the hydraulic pump is equal to or larger than a set value,
(III) When the fluctuation range of the engine speed is less than the set value,
(IV) When at least one of the regeneration stop conditions when the accumulation amount detected by the accumulation amount detection means is not more than the set value is met, the fuel supply means supplies fuel to the exhaust gas filter. The playback operation is stopped by stopping the playback operation.

  The invention according to claim 8 is the structure according to any one of claims 1 to 7, further comprising display means for displaying the accumulation amount of the harmful substance of the exhaust gas filter and the temperature in the filter.

  According to the present invention, on the premise of the forced combustion method, the temperature in the filter is detected, and when the temperature in the filter is not more than a set value that is a temperature suitable for combustion (combustion temperature), the temperature in the filter is not less than the set value. The fuel is supplied after the temperature raising operation for raising the temperature (the operation for increasing the engine load by increasing the pump pressure by the relief action in claim 2, the operation for increasing the engine speed in claim 3) is automatically performed. Therefore, it is possible to reliably perform the filter regeneration operation and prevent waste of fuel.

  According to the invention of claim 4, since the engine speed is limited to the set range during the regeneration operation, the engine speed can be kept within a range in which combustion is not unstable and noise is not excessive. it can.

  According to the invention of claim 5, during the regeneration operation, the capacity of the hydraulic pump driven by the engine is limited to a set value or less, so that the change in the engine speed due to the change in the pump capacity during the regeneration operation is prevented, and the combustion is stabilized. Can be achieved.

  On the other hand, since the operation of the control valve is stopped by the operation stop means during the regeneration operation, the combustion can be stabilized.

  According to the invention of claim 7, when the operating means is operated during the regeneration operation, when the fluctuation range of the discharge pressure of the hydraulic pump is equal to or larger than a set value, when the fluctuation range of the engine speed is equal to or larger than the set value, And when at least one of the regeneration stop conditions when the deposition amount detected by the deposition amount detection means is equal to or less than the set value is met, that is, when the operator intends to perform a mechanical operation (regeneration stop), or Since the regeneration operation is stopped when the fluctuation of the pump pressure or the engine speed is large and the stable regeneration operation is difficult, it is possible to respond to the intention of the operator or prevent the waste of fuel.

  According to the eighth aspect of the present invention, the accumulation amount of the harmful substance in the exhaust gas filter and the temperature in the filter are displayed by the display means, so the regeneration time can be predicted to the operator by displaying the accumulation amount. Further, by displaying the temperature in the filter, the operator can recognize that the temperature raising operation is performed after the regeneration start switch is operated.

  Note that these displays may be performed in a format for comparing with the respective set values (for example, what percentage of the set amount is the set value and how much the temperature in the filter is lower than the set value).

1 is a circuit and block configuration diagram of an exhaust gas treatment apparatus according to an embodiment of the present invention. It is a flowchart for demonstrating the effect | action of the apparatus.

  The overall configuration of the exhaust gas treatment apparatus according to the embodiment will be described with reference to FIG.

  The variable displacement hydraulic pump 2 is driven by the engine 1, and the oil discharged from the hydraulic pump 2 is supplied to a plurality of hydraulic actuators (here, only one hydraulic cylinder is shown) 4 through a control valve 3.

  The control valve 3 is configured as a hydraulic pilot switching valve that is switched and operated by a pilot pressure from remote control valves 5 and 5 as operating means to control the direction and flow rate of pressure oil supply to the hydraulic actuator 4.

  An operation stop valve that opens / closes the pilot pressure supply line 7 that connects the remote control valves 5 and 5 and the pilot pump 6 that serves as a hydraulic pressure source to supply / shut off the pilot primary pressure to the remote control valves 5 and 5. (Electromagnetic valve) 8 is provided. T is a tank.

  In addition, a relief valve 10 that regulates the maximum pressure of the circuit is connected to the discharge line 9 of the hydraulic pump 2, and an unload passage 11 that unloads excess pump discharge oil to the tank T is connected to the discharge line 9. The unload passage 11 is provided with an unload passage opening / closing valve 12 and a throttle 13 as unload passage blocking means for opening and closing the passage 11.

  On the other hand, an exhaust gas filter 15 is provided in the exhaust passage 14 for releasing the exhaust gas from the engine 1 to the outside, and harmful substances such as PM in the exhaust gas are removed by the exhaust gas filter 15.

  A fuel supply line 17 as fuel supply means for supplying fuel in the fuel tank 16 to the exhaust gas filter 15 for filter regeneration (combustion) and a fuel supply valve 18 for opening and closing the line 17 are provided. Fuel for combustion is supplied into the exhaust gas filter 15 by a pump (not shown) in a state where 18 is open.

  The control means includes an engine control unit 19 that controls the rotational speed of the engine 1, a pump regulator 20 that controls the discharge amount (tilt) of the hydraulic pump 2, and a controller 21. Various commands for regeneration control, that is, an open / close command for the operation stop valve 8 and the unload passage open / close valve 12, an engine speed command for the engine control unit 19, and a pump tilt (pump capacity = pump flow rate) command for the pump regulator 20 Are each output.

  Further, a regeneration start switch 22 for starting the filter regeneration operation based on the operator's intention is provided, and temperature detection for detecting the temperature in the exhaust gas filter 15 as detection means for obtaining information for starting filter regeneration and the like. Pilot line connecting temperature sensor 23 as means, accumulation amount sensor 24 as accumulation amount detection means for detecting accumulation amount of harmful substances such as PM on filter 15, remote control valves 5, 5 and control valve 3 Pilot pressure sensors 26 and 26 as operation detecting means for detecting whether or not the remote control valves 5 and 5 are operated by pilot pressures 25 and 25 and a pump pressure sensor 27 for detecting pump discharge pressure are provided.

  As the temperature detection means, instead of the method of directly detecting the exhaust gas filter temperature by the temperature sensor 23, the engine load is determined from the rotational speed command sent from the engine control unit 19 to the engine 1 and the engine rotational speed with respect to the command. May be used to estimate the temperature in the filter from this engine load.

  Further, as a means for detecting the accumulation amount of harmful substances on the exhaust gas filter 15, instead of the method of directly detecting by the accumulation amount sensor 24, an estimated value based on the differential pressure before and after the exhaust gas filter 15 or the accumulation of the engine load is obtained. The required method may be adopted.

  Further, a display means 28 is connected to the controller 21, and the amount of accumulation detected by the temperature sensor 23 and the accumulation amount sensor 24 and the temperature in the filter are displayed on the display means 28. This display may be simply a numerical display on the monitor, or a form in which the detected value is compared with each set value (for example, how much of the set amount is the set value or how much the temperature in the filter is lower than the set value). In addition, an alarm may be issued regarding the amount of accumulation to prompt the operator to start regeneration.

  The controller 21 starts filter regeneration and performs regeneration control based on the signals from the detection means. The operation of this point will be described with reference to the flowchart of FIG.

  In step S1, it is determined whether or not the regeneration start switch 22 has been operated. If YES, whether or not the accumulation amount detected by the accumulation amount sensor 24 is equal to or greater than a set value stored as a value that requires regeneration (step S2). And whether or not the temperature in the filter detected by the temperature sensor 23 is equal to or higher than a set value stored as a value suitable for combustion of harmful substances (step S3).

  When both steps S2 and S3 are YES (deposition amount> set value and temperature> set value), it is determined that the conditions for regeneration are satisfied, and the unload passage opening / closing valve 12 is opened in step S4, and in step S5. Open the fuel supply valve 18.

  Thereby, fuel is supplied to the exhaust gas filter 15 and combustion of harmful substances (filter regeneration) is started.

  Thereafter, in step S6, the fluctuation range of the pump pressure is compared with a set value determined as a value that can ensure a stable regeneration (combustion) action.

  Here, if the pump pressure fluctuation range is equal to or less than the set value (NO), it is then determined in step S7 whether or not the remote control valves 5 and 5 are operated (machine operation). In step S8, it is determined whether or not the fluctuation range of the engine speed exceeds a set value for ensuring a stable regeneration action, similarly to the fluctuation range of the pump pressure.

  If NO (does not exceed), the process proceeds to step S9, where the operation stop valve 8 is closed to prohibit the machine operation during regeneration.

  In subsequent step S10, the engine speed is limited to a set value that is neither too high nor too low for combustion stabilization and noise suppression, and in step S11, the pump capacity is limited to the set value for combustion stabilization. Return to step S1.

  On the other hand, if NO in step S3, that is, if the filter temperature has not reached the set value at the start of regeneration, the temperature raising operation is necessary and the process proceeds to step S12, and the unload passage opening / closing valve 12 is closed as the temperature raising operation.

  More specifically, the filter regeneration is started when the operator turns on the regeneration start switch 22 with the intention of starting the regeneration after the work is completed. Accordingly, the remote control valves 5 and 5 are not operated and the control valve 3 is in a neutral state, and the hydraulic pump 2 discharges only the standby flow rate. This standby flow rate is unloaded to the tank T through the unload passage opening / closing valve 12. Loaded.

  When the unload passage opening / closing valve 12 is closed in this state as described above, the destination of the standby flow rate disappears, the pressure in the pump discharge line 9 rises to the maximum pressure, and the relief valve 10 performs the relief action.

  This relief action increases the engine load and raises the temperature in the filter toward the start of regeneration.

  In step S13, at this stage, the fuel supply valve 18 is opened because it cannot be regenerated. In step S14, the operation stop valve 8 is opened. In steps S15 and S16, the engine speed limit and the pump capacity limit are released.

  Thereafter, when the temperature in the filter becomes equal to or higher than the set value by the temperature raising operation, YES is determined in step S3, the unload passage opening / closing valve 12 is opened in step S4, and the fuel supply valve 18 is opened in step S5 to start regeneration. The

  In the case of NO in step S1 (whether the regeneration start switch 22 is turned on), in the case of NO in step S2 (whether the accumulation amount has exceeded the set value), or in the case of YES in steps S6 to S8 In step S13, the reproduction is not necessary or the reproduction is not continued.

  In other words, if the answer is NO in step S1, the reproduction operation is not started because the operator does not intend to start or continue the reproduction.

  In the case of NO in step S2, the regeneration operation is not started because the accumulation amount is small and regeneration is not necessary, or the regeneration operation is stopped as the accumulation amount has decreased below the set value as a result of the regeneration operation (regeneration completion). To do.

  On the other hand, in the case of YES in steps S6 to S8, that is, when a mechanical operation (operation of the remote control valves 5 and 5) is performed during the regeneration operation, and the fluctuation range of the pump pressure is equal to or larger than the set value, the engine speed When at least one of the fluctuation ranges is greater than the set value, that is, when the operator intends to operate the machine (regeneration stop), or the fluctuation of the pump pressure or engine speed is large and stable. When playback is difficult, stop the playback operation.

  As described above, assuming the forced combustion method, the temperature in the filter is detected, and when the temperature in the filter is equal to or lower than a set value that is a temperature suitable for combustion (combustion temperature), the temperature in the filter is increased to the set value or higher. The fuel regeneration (filter regeneration operation) is started after automatically performing the temperature raising operation (operation to increase the engine load by increasing the pump pressure by the relief action), so that the filter regeneration operation can be performed reliably. , Fuel waste can be prevented.

  Further, during the regenerating operation, the engine speed and the pump capacity are limited to the set ranges, and the operation (mechanical operation) of the control valve 3 is stopped by the operation stop valve 8, so that the regenerating operation can be stabilized. Furthermore, engine noise can be suppressed by limiting the engine speed.

  On the other hand, when the mechanical operation is performed during the regeneration operation, when the fluctuation range of the discharge pressure of the hydraulic pump is equal to or larger than the set value, when the fluctuation range of the engine speed is equal to or smaller than the set value, and by the accumulation amount detection means When at least one of the regeneration stop conditions is met when the detected accumulation amount falls below the set value, that is, when the operator intends to operate the machine (regeneration stop), or the pump pressure or engine speed Since the regeneration operation is stopped when the fluctuation is large and a stable regeneration operation is difficult, it is possible to respond to the operator's intention or prevent waste of fuel.

  Furthermore, since the accumulation amount of harmful substances in the exhaust gas filter and the temperature inside the filter are displayed by the display means, the regeneration time can be predicted to the operator by displaying the accumulation amount. Further, by displaying the temperature in the filter, the operator can recognize that the temperature raising operation is performed after the regeneration start switch is operated.

  Although omitted in the flowchart, the detected accumulation amount and the temperature in the filter are always displayed by the display means 28.

  By the way, as the temperature raising operation when the temperature in the filter is equal to or lower than the set value at the start of regeneration, the configuration using the relief action is used in the above embodiment, but a method of increasing the engine speed may be used. In this case, in the flowchart of FIG. 2, in step S4, a process of “increasing the engine speed” is performed instead of “opening the unload passage opening / closing valve” in the above embodiment.

  Or you may perform both a relief effect | action and an engine speed increase simultaneously.

DESCRIPTION OF SYMBOLS 1 Engine 2 Hydraulic pump T Tank 3 Control valve 4 Hydraulic actuator 5, 5 Remote control valve (operating means)
6 Pilot pump 7 Pilot pressure supply line 8 Operation stop valve (operation stop means)
9 Pump discharge pipe 10 Relief valve 11 Unload passage 12 Unload passage on-off valve (unload passage shut-off means)
DESCRIPTION OF SYMBOLS 14 Exhaust passage 15 Exhaust gas filter 16 Fuel tank which comprises fuel supply means 17 Fuel supply line 18 Fuel supply valve 19 Engine control part which comprises control means 20 Pump controller 21 Same as above Controller 22 Regeneration start switch 23 Temperature sensor (temperature detection means)
24 Deposition amount sensor (deposition amount detection means)
25 Pilot line 26 Pilot pressure sensor (operation detection means)
27 Pump pressure sensor (pump pressure detection means)
28 Display means

Claims (8)

  An engine, an exhaust gas filter for removing harmful substances in the exhaust gas emitted from the engine, a regeneration start switch operated by an operator to command regeneration start of the exhaust gas filter, and a fuel supply means for supplying fuel to the exhaust gas filter And an accumulation amount detection means for detecting the accumulation amount of harmful substances in the exhaust gas filter, a temperature detection means for detecting the temperature in the exhaust gas filter, and a control means, the control means having the regeneration start switch When operated, the accumulation amount detected by the accumulation amount detection means is not less than a set value as a value that requires regeneration, and the exhaust gas filter temperature detected by the temperature detection means is suitable for the combustion of harmful substances. Fuel is supplied to the exhaust gas filter by the fuel supply means on condition that the value is equal to or greater than the set value The filter is regenerated by burning the harmful substances accumulated on the filter, and when the exhaust gas filter temperature is below the set value, the temperature rise operation is performed to raise the filter temperature to the set value or more, and then the regeneration operation is performed. An exhaust gas treatment apparatus for a construction machine, characterized in that the apparatus is configured to start.   The discharge line of the hydraulic pump driven by the engine is connected to a relief line having a relief valve and an unload passage for unloading excess oil from the discharge oil of the hydraulic pump. An unload passage blocking means for closing the passage is provided in the passage, and the control means is configured to block the unload passage by the unload passage blocking means and operate the relief valve as the temperature raising operation. The exhaust gas treatment apparatus for a construction machine according to claim 1, which is configured.   3. The construction according to claim 1, further comprising engine speed detecting means for detecting the engine speed, wherein the control means is configured to increase the engine speed as a temperature raising operation. Exhaust gas treatment equipment for machines.   The engine speed detecting means for detecting the engine speed is provided, and the control means is configured to limit the engine speed to a set range during the regeneration operation. The exhaust gas treatment apparatus for a construction machine according to any one of the above.   A variable displacement hydraulic pump is used as the hydraulic pump driven by the engine, and the control means is configured to limit the capacity of the hydraulic pump to a set value or less during a regeneration operation. The exhaust gas treatment apparatus for a construction machine according to any one of claims 1 to 4.   A hydraulic pump driven by the engine, a control valve for controlling the operation of a hydraulic actuator using the hydraulic pump as a hydraulic source, an operating means for operating the control valve, and an operation of the control valve by operating the operating means 6. An operation stop means for stopping the control valve, and the control means is configured to stop the operation of the control valve by the operation stop means during the regeneration operation. Exhaust gas treatment equipment for construction machinery as described in 1. A hydraulic pump driven by the engine, a control valve for controlling the operation of a hydraulic actuator using the hydraulic pump as a hydraulic source, an operating means for operating the control valve, and an operation for detecting whether or not the operating means is operated Detecting means, pump pressure detecting means for detecting the discharge pressure of the hydraulic pump, and engine speed detecting means for detecting the engine speed, and the control means during the regeneration operation,
(I) When the operation means is operated,
(II) When the fluctuation range of the discharge pressure of the hydraulic pump is equal to or larger than a set value,
(III) When the fluctuation range of the engine speed is less than the set value,
(IV) When at least one of the regeneration stop conditions when the accumulation amount detected by the accumulation amount detection means is not more than the set value is met, the fuel supply means supplies fuel to the exhaust gas filter. The exhaust gas treatment device for a construction machine according to any one of claims 1 to 6, wherein the exhaust gas treatment device is configured to stop the regeneration operation.   The exhaust gas treatment apparatus for a construction machine according to any one of claims 1 to 7, further comprising display means for displaying an accumulation amount of a harmful substance of the exhaust gas filter and a temperature in the filter.

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