US20120279203A1 - Exhaust gas purification system for hydraulic operating machine - Google Patents

Exhaust gas purification system for hydraulic operating machine Download PDF

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Publication number
US20120279203A1
US20120279203A1 US13/393,871 US201113393871A US2012279203A1 US 20120279203 A1 US20120279203 A1 US 20120279203A1 US 201113393871 A US201113393871 A US 201113393871A US 2012279203 A1 US2012279203 A1 US 2012279203A1
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Prior art keywords
exhaust gas
hydraulic
exhaust
increasing
gas purification
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Abandoned
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US13/393,871
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English (en)
Inventor
Yasushi Arai
Kouji Ishikawa
Shohei Kamiya
Hidenobu Tsukada
Tsuyoshi Nakamura
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Hitachi Construction Machinery Co Ltd
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Hitachi Construction Machinery Co Ltd
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Assigned to HITACHI CONSTRUCTION MACHINERY CO., LTD. reassignment HITACHI CONSTRUCTION MACHINERY CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NAKAMURA, TSUYOSHI, ISHIKAWA, KOUJI, TSUKADA, HIDENOBU, ARAI, YASUSHI, KAMIYA, SHOHEI
Publication of US20120279203A1 publication Critical patent/US20120279203A1/en
Abandoned legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
    • F02D41/0245—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus by increasing temperature of the exhaust gas leaving the engine
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9495—Controlling the catalytic process
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/08—Superstructures; Supports for superstructures
    • E02F9/0858—Arrangement of component parts installed on superstructures not otherwise provided for, e.g. electric components, fenders, air-conditioning units
    • E02F9/0866—Engine compartment, e.g. heat exchangers, exhaust filters, cooling devices, silencers, mufflers, position of hydraulic pumps in the engine compartment
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/2058—Electric or electro-mechanical or mechanical control devices of vehicle sub-units
    • E02F9/2062—Control of propulsion units
    • E02F9/2066—Control of propulsion units of the type combustion engines
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2232—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps
    • E02F9/2235—Control of flow rate; Load sensing arrangements using one or more variable displacement pumps including an electronic controller
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2296—Systems with a variable displacement pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D29/00—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D29/00—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
    • F02D29/04—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto peculiar to engines driving pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/027—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus
    • F02D41/029—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to purge or regenerate the exhaust gas treating apparatus the exhaust gas treating apparatus being a particulate filter
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1448—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an exhaust gas pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/01—Engine exhaust gases
    • B01D2258/012—Diesel engines and lean burn gasoline engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/06—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a temperature sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/08—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being a pressure sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N2590/00—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines
    • F01N2590/08—Exhaust or silencing apparatus adapted to particular use, e.g. for military applications, airplanes, submarines for heavy duty applications, e.g. trucks, buses, tractors, locomotives
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F02D41/024—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus
    • F02D2041/026—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus to increase temperature of the exhaust gas treating apparatus using an external load, e.g. by increasing generator load or by changing the gear ratio
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to an exhaust gas purification system for a hydraulic operating machine.
  • the invention relates to an exhaust gas purification system for a hydraulic operating machine (e.g., hydraulic shovel) for recovering a filter of an exhaust gas purification device installed in the hydraulic operating machine by combusting and removing deposits accumulated on the filter.
  • a hydraulic operating machine e.g., hydraulic shovel
  • Patent Literatures 1 and 2 Conventional exhaust gas purification systems for purifying the exhaust gas of a diesel engine include those described in Patent Literatures 1 and 2, for example.
  • an exhaust gas purification device including a filter called “particulate filter” DPF: Diesel Particulate Filter
  • PM particulate matter
  • the exhaust gas purification system executes automatic recovery control and manual recovery control, for example.
  • an oxidation catalyst is placed upstream of the filter and the amount of the PM accumulated on the filter (PM accumulation amount) is estimated by detecting the differential pressure across the filter.
  • PM accumulation amount the amount of the PM accumulated on the filter
  • the temperature of the exhaust gas is increased automatically when the PM accumulation amount has exceeded a prescribed value, by which the oxidation catalyst is activated and the PM accumulated on the filter is combusted and removed.
  • a warning lamp is lit up so as to urge the operator to start recovery control by manual operation in a state in which the vehicle is stopped.
  • a manual recovery switch is turned ON by the operator, the temperature of the exhaust gas is increased, by which the oxidation catalyst is activated and the PM accumulated on the filter is combusted and removed.
  • an exhaust resistance sensor is installed in an exhaust gas processing device of a hydraulic operating machine.
  • the degree of the filter clogging is detected.
  • a hydraulic load is exerted on the engine by simultaneously increasing the discharge rate and the discharge pressure of a hydraulic pump. With the increase in the engine load, the output power of the engine increases and the exhaust gas temperature rises, by which the deposits accumulated on the filter are combusted and the filter is recovered.
  • the degree of the clogging is detected by the exhaust resistance sensor installed in the exhaust gas processing device.
  • the discharge rate and the discharge pressure of the hydraulic pump are simultaneously increased to increase the engine load and raise the exhaust gas temperature, thereby carrying out the recovery of the filter.
  • the atmospheric temperature changes in a wide range (e.g., ⁇ 30° C.-40° C.) in the actual operating environment of a hydraulic operating machine and the exhaust gas temperature rises accordingly when the atmospheric temperature rises. Therefore, the technique of the Patent Literature 2 can increase the exhaust gas temperature to an unnecessary high level by the exhaust gas temperature increasing control and consume the fuel wastefully.
  • the technique of the Patent Literature 2 specifies that the exhaust gas temperature increasing control is desired to be executed in a non-operating state (in which the operator is not operating the machine/vehicle). In this case, an operation interruption time (during which the operation or work has to be interrupted) becomes necessary.
  • a first object of the present invention is to provide an exhaust gas purification system for a hydraulic operating machine that is capable of executing the recovery process of the exhaust gas purification device with reliability by increasing the exhaust gas temperature irrespective of the operating environment and capable of keeping the fuel consumption at a minimum necessary level.
  • a second object of the present invention is to provide an exhaust gas purification system for a hydraulic operating machine that is capable of executing the recovery process of the exhaust gas purification device with reliability by increasing the exhaust gas temperature irrespective of the operating environment, capable of keeping the fuel consumption at a minimum necessary level, and capable of reducing the operation interruption frequency of the machine.
  • an invention described in claim 1 provides an exhaust gas purification system for a hydraulic operating machine equipped with a diesel engine, an exhaust gas purification device provided in an exhaust line of the engine, a variable displacement hydraulic pump driven by the engine, a pump displacement adjusting device for controlling the displacement of the hydraulic pump, and at least one hydraulic actuator driven by hydraulic fluid discharged from the hydraulic pump.
  • the exhaust gas purification system comprises: an exhaust resistance sensor for detecting exhaust resistance of the exhaust gas purification device; an exhaust temperature sensor for detecting temperature of exhaust gas in the exhaust gas purification device; a pump discharge pressure increasing device provided in a hydraulic line, through which the hydraulic fluid discharged from the hydraulic pump flows, for increasing discharge pressure of the hydraulic pump; and a recovery control device for executing recovery of the exhaust gas purification device by combusting and removing particulate matter accumulated in the exhaust gas purification device when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded a set value.
  • the recovery control device includes an exhaust temperature increasing control device which increases the exhaust gas temperature so as to make the exhaust gas temperature detected by the exhaust temperature sensor reach a preset value by increasing absorption torque of the hydraulic pump by operating at least the latter one (i.e., the pump discharge pressure increasing device) of the pump displacement adjusting device and the pump discharge pressure increasing device when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded the set value.
  • an exhaust temperature increasing control device which increases the exhaust gas temperature so as to make the exhaust gas temperature detected by the exhaust temperature sensor reach a preset value by increasing absorption torque of the hydraulic pump by operating at least the latter one (i.e., the pump discharge pressure increasing device) of the pump displacement adjusting device and the pump discharge pressure increasing device when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded the set value.
  • the exhaust gas temperature is increased so as to make the exhaust gas temperature detected by the exhaust temperature sensor reach the preset value by operating at least the pump discharge pressure increasing device. Therefore, the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment and the economic efficiency can be improved by keeping the fuel consumption at a minimum necessary level.
  • the exhaust temperature increasing control device in the exhaust gas purification system according to claim 1 controls an operation amount of at least the latter one of the pump displacement adjusting device and the pump discharge pressure increasing device so that an increment of the absorption torque of the hydraulic pump amounts to 20%-30% of maximum torque of the engine.
  • the present inventors have confirmed that the exhaust gas temperature can be increased to approximately 250° C.-350° C. without causing any problem to the operation of the hydraulic operating machine driving hydraulic actuators if the hydraulic absorption torque generated by the pump displacement adjusting device and the pump discharge pressure increasing device is approximately 20%-30% of the maximum torque of the engine.
  • the present invention has been made based on these findings.
  • the recovery process of the exhaust gas purification device can be performed by increasing the exhaust gas temperature by the exhaust temperature increasing control without causing any problem to the operation of the hydraulic operating machine. Consequently, working efficiency can be increased through the improvement of workability during the execution of the recovery control and the reduction of the operation interruption frequency of the hydraulic operating machine.
  • the exhaust temperature increasing control device includes an exhaust temperature adjusting device which adjusts at least one selected from an operation amount of the pump displacement adjusting device, an operation amount of the pump discharge pressure increasing device and an increment of revolution speed of the engine so that the exhaust gas temperature remains within a preset range after the exhaust gas temperature detected by the exhaust temperature sensor has been increased to the preset value.
  • the exhaust gas temperature T can be reliably controlled and kept within the preset temperature range. Consequently, ill effect on the operation can be minimized in the recovery control in the operating state. In the recovery control in the non-operating state, unnecessary increase in the engine load can be avoided, the fuel consumption can be kept at a minimum necessary level, and the economic efficiency can be improved.
  • the recovery control device is an automatic recovery control device which automatically starts operation when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded the set value.
  • the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature even in low-load operation in the operating state.
  • the exhaust gas purification system according to claim 4 further comprises operation detecting means for detecting whether the hydraulic actuator is being driven or not.
  • the exhaust temperature increasing control device increases the exhaust gas temperature by increasing the absorption torque of the hydraulic pump by operating at least the latter one of the pump displacement adjusting device and the pump discharge pressure increasing device when the hydraulic actuator is being driven.
  • the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature even in low-load operation in the operating state.
  • the exhaust temperature increasing control device increases the exhaust gas temperature by increasing revolution speed of the engine to a preset revolution speed and increasing the absorption torque of the hydraulic pump by operating the pump displacement adjusting device and the pump discharge pressure increasing device.
  • the recovery process of the exhaust gas purification device can be executed with reliability even in the non-operating state by securely increasing the exhaust gas temperature by the combination of the absorption torque increasing control of the hydraulic pump and the engine revolution speed increasing control.
  • the exhaust gas purification system according to any one of claims 1 - 3 further comprises: operation permission state detecting means for detecting whether the hydraulic operating machine is in an operation permission state or not; and manual recovery instruction means.
  • the recovery control device is a manual recovery control device which issues an alarm when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded a second set value and starts operation when the operation permission state detecting means detects that the hydraulic operating machine is not in the operation permission state and there is an instruction by the manual recovery instruction means.
  • the exhaust temperature increasing control device increases the exhaust gas temperature by increasing revolution speed of the engine to a preset revolution speed and increasing the absorption torque of the hydraulic pump by operating the pump displacement adjusting device and the pump discharge pressure increasing device.
  • the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment and the economic efficiency can be improved by keeping the fuel consumption at a minimum necessary level.
  • the exhaust temperature increasing control device previously stores an exhaust resistance threshold value, for judging whether the recovery of the exhaust gas purification device by the automatic recovery control device is necessary or not, as a function of engine revolution speed and an engine load, determines the exhaust resistance threshold value by referring to current engine revolution speed and engine load and inputting them to the function, and sets the determined exhaust resistance threshold value as the set value.
  • an appropriate value incorporating the operating status of the engine can be set as the set value, by which proper recovery control can be performed.
  • the automatic recovery control device sets the set value of the exhaust resistance at a lower value when the hydraulic actuator is not being driven compared to cases where the hydraulic actuator is being driven.
  • the recovery control device includes an automatic recovery control device which automatically starts operation when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded the set value and a manual recovery control device which issues an alarm when the exhaust resistance detected by the exhaust resistance sensor has reached or exceeded the set value and starts operation when the operation permission state detecting means detects that the hydraulic operating machine is not in the operation permission state and there is an instruction by the manual recovery instruction means.
  • the set value in the automatic recovery control device is set lower than the set value in the manual recovery control device.
  • the frequency of the automatic recovery control increases and the frequency of the manual recovery control decreases due to the output value of the exhaust resistance sensor increasing to the second set value less frequently. Consequently, the operation interruption frequency of the hydraulic operating machine can be reduced.
  • the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment and the economic efficiency can be improved by keeping the fuel consumption at a minimum necessary level.
  • the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment, the economic efficiency can be improved by keeping the fuel consumption at a minimum necessary level, and the working efficiency can be increased through the improvement of workability during the execution of the recovery control and the reduction of the operation interruption frequency of the hydraulic operating machine.
  • FIG. 1 is a schematic diagram showing a hydraulic driving system of a hydraulic operating machine equipped with an exhaust gas purification system in accordance with a first embodiment of the present invention.
  • FIG. 2 is a flow chart showing the contents of a calculation process for positive control and pump torque limiting control executed by a controller.
  • FIG. 3 is a graph showing an absorption torque property of a hydraulic pump acquired as a result of pump torque limiting control.
  • FIG. 4 is a schematic diagram showing the external appearance of a hydraulic shovel as an example of the hydraulic operating machine equipped with the hydraulic driving system and the exhaust gas purification system shown in FIG. 1 .
  • FIG. 5 is a flow chart showing the overall process flow of automatic recovery control when the hydraulic operating machine is in an operation permission state.
  • FIG. 6 is a flow chart showing the contents of the automatic recovery control when the hydraulic operating machine is in the operation permission state and in an operating state.
  • FIG. 7 is a flow chart showing the contents of the automatic recovery control when the hydraulic operating machine is in the operation permission state and in a non-operating state.
  • FIG. 8 is a flow chart showing the contents of manual recovery control when the hydraulic operating machine is in an operation prohibition state.
  • FIG. 9 is a graph showing the relationship between the amount of PM accumulated on a filter in an exhaust gas purification device and the exhaust resistance of the filter (differential pressure across the filter) at the rated engine revolution speed and the maximum engine load.
  • FIG. 10 is a graph showing changes in the relationship between the PM accumulation amount and the exhaust resistance shown in FIG. 9 depending on the engine revolution speed and the engine load.
  • FIG. 11 is a flow chart showing the contents of exhaust gas temperature increasing control (step S 312 in FIG. 6 ).
  • FIG. 12 is a flow chart showing the contents of a process including exhaust gas temperature increasing control (step S 412 in FIG. 7 ).
  • FIG. 13 is a schematic diagram showing a hydraulic driving system of a hydraulic operating machine equipped with an exhaust gas purification system in accordance with a second embodiment of the present invention.
  • FIG. 14 is a flow chart showing the contents of a calculation process for the positive control of the hydraulic pump executed by a controller.
  • FIG. 15 is a graph like FIG. 3 showing the absorption torque property of the hydraulic pump acquired as a result of the pump torque limiting control.
  • FIG. 16 is a flow chart showing the details of the hydraulic absorption torque increasing control in the step S 312 in FIG. 6 regarding the automatic recovery control in the operating state.
  • FIG. 17 is a flow chart (corresponding to FIG. 6 in the first embodiment) showing the contents of the automatic recovery control in the operating state executed by an exhaust gas purification system in accordance with a third embodiment of the present invention.
  • FIG. 18 is a flow chart (corresponding to FIG. 7 in the first embodiment) showing the contents of the automatic recovery control in the non-operating state executed by the exhaust gas purification system of the third embodiment of the present invention.
  • FIG. 19 is a flow chart (corresponding to FIG. 8 in the first embodiment) showing the contents of the manual recovery control executed by the exhaust gas purification system of the third embodiment of the present invention when the hydraulic operating machine is in the operation prohibition state.
  • FIG. 1 is a schematic diagram showing a hydraulic driving system of a hydraulic operating machine equipped with an exhaust gas purification system in accordance with a first embodiment of the present invention.
  • the hydraulic driving system comprises a diesel engine (hereinafter properly abbreviated as an “engine”) 1 , a main hydraulic pump 2 of the variable displacement type, a pilot pump 3 , a hydraulic actuator 25 , flow/directional control valves 4 and 5 , a control lever device 8 and a main relief valve 9 .
  • the hydraulic pump 2 and the pilot pump 3 are driven by the engine 1 .
  • the hydraulic actuator 25 is driven by hydraulic fluid (oil) discharged from the hydraulic pump 2 .
  • the flow/directional control valve 4 controls the flow rate and the direction of the hydraulic fluid supplied from the hydraulic pump 2 to the hydraulic actuator 25 .
  • the flow/directional control valve 5 controls the flow rate and the direction of hydraulic fluid supplied from the hydraulic pump 2 to other hydraulic actuators (not shown).
  • the control lever device 8 is used for operating the hydraulic actuator 25 .
  • the main relief valve 9 regulates the maximum pressure of a discharging hydraulic line of the hydraulic pump 2 .
  • the control lever device 8 includes pilot valves (pressure reducing valves) 8 a and 8 b , to which hydraulic fluid is supplied from the pilot pump 3 .
  • the discharge pressure of the pilot pump 3 is controlled by a pilot relief valve 10 at a constant level.
  • a control lever 8 c of the control lever device 8 When a control lever 8 c of the control lever device 8 is operated, either the pilot valve 8 a or the pilot valve 8 b moves depending on the direction and the amount of the operation, by which operating pilot pressure is generated.
  • a spool of the flow/directional control valve 4 is slid and the hydraulic actuator 25 is operated.
  • the hydraulic driving system further comprises a pilot cut valve 11 , a safety lever 12 , a switch 13 , a regulator 14 , pressure sensors 16 and 17 , a revolution sensor 18 , an engine control dial 19 and a controller 20 .
  • the pilot cut valve 11 is attached to a discharging hydraulic line of the pilot pump 3 .
  • the safety lever 12 (called “gate lock lever”) is placed at the entrance to the operator's seat.
  • the switch 13 operates in conjunction with the safety lever 12 .
  • the regulator 14 (pump displacement adjusting device) adjusts the tilting angle (capacity or displacement volume) of the hydraulic pump 2 .
  • the pressure sensor 16 (operation detecting means) detects the operating pilot pressure generated by the pilot valves 8 a and 8 b as the operation amount of the control lever device 8 .
  • the pressure sensor 17 detects the discharge pressure of the hydraulic pump 2 .
  • the revolution sensor 18 detects the revolution speed of the engine 1 .
  • the engine control dial 19 outputs an instruction signal which specifies a target revolution speed of the engine 1 .
  • a plurality of shuttle valves are arranged along signal paths for the pressure sensor 16 for detecting the operating pilot pressure.
  • the operating pilot pressure is generated by either the pilot valve 8 a or 8 b
  • the operating pilot pressure is lead to the pressure sensor 16 via the shuttle valves 21 a and 21 b and is detected by the pressure sensor 16 .
  • a control lever device for another actuator (not shown) is operated and operating pilot pressure is generated accordingly, the operating pilot pressure is lead to the pressure sensor 16 via a shuttle valve (not shown) and the shuttle valve 21 b and is detected by the pressure sensor 16 .
  • the controller 20 detects the operation amount of the control lever device 8 and the engine revolution speed at that time with the pressure sensor 16 and the revolution sensor 18 , respectively, calculates a target tilting angle of the hydraulic pump 2 through a calculation process for positive control and pump torque limiting control (also called “pump horsepower control”), and changes the tilting angle of the hydraulic pump 2 by controlling the regulator 14 to achieve the target tilting angle.
  • a target tilting angle of the hydraulic pump 2 through a calculation process for positive control and pump torque limiting control (also called “pump horsepower control”), and changes the tilting angle of the hydraulic pump 2 by controlling the regulator 14 to achieve the target tilting angle.
  • the safety lever 12 can be operated to an operation permission position and an operation prohibition position.
  • the switch 13 remains in an ON state when the safety lever 12 is at the operation permission position, and in an OFF state when the safety lever 12 is at the operation prohibition position.
  • the controller 20 detects the ON/OFF state of the switch 13 operating in conjunction with the safety lever 12 as above and opens the pilot cut valve 11 to supply the hydraulic fluid to the pilot valves 8 a and 8 b of the control lever device 8 only when the safety lever 12 is at the operation permission position (only when the switch 13 is ON).
  • the controller 20 controls the revolution speed and torque of the engine 1 by controlling an electronic governor 1 a (which controls the fuel injection quantity of the engine 1 ) according to the instruction signal and the measurement value of the revolution sensor 18 (current engine revolution speed).
  • FIG. 2 is a flow chart showing the contents of the calculation process for the positive control and the pump torque limiting control executed by the controller 20 .
  • the controller 20 calculates a demanded flow rate Qr for the positive control by detecting the operation amount of the control lever device 8 with the pressure sensor 16 (step S 10 ). This calculation is executed by multiplying the measurement value of the pressure sensor 16 by a prescribed demanded flow rate conversion factor, for example. Subsequently, the controller 20 calculates the target tilting angle qr of the hydraulic pump 2 necessary for making the hydraulic pump 2 discharge the demanded flow rate Qr (step S 15 ). This calculation is executed by dividing the demanded flow rate Qr by the revolution speed of the hydraulic pump 2 and multiplying the quotient by a prescribed conversion factor. The revolution speed of the hydraulic pump 2 is determined from the measurement value of the revolution sensor 18 .
  • the controller 20 calculates a maximum tilting angle qmax of the hydraulic pump 2 for the pump torque limiting control according to the discharge pressure Pp of the hydraulic pump 2 inputted from the pressure sensor 17 (step S 20 ). This calculation is executed by previously setting a constant maximum absorption torque property of the hydraulic pump 2 , checking the discharge pressure Pp of the hydraulic pump 2 with the property, and thereby determining a corresponding tilting angle (maximum tilting angle). Subsequently, the controller 20 compares the target tilting angle qr with the maximum tilting angle qmax (step S 25 ).
  • the controller 20 calculates a control signal for achieving the target tilting angle qr and outputs the control signal to the regulator 14 (step S 30 ).
  • the controller 20 calculates a control signal for achieving the maximum tilting angle qmax and outputs the control signal to the regulator 14 (step S 35 ).
  • the regulator 14 changes the tilting angle of the hydraulic pump 2 so as to achieve the target tilting angle qr (positive control).
  • the regulator 14 changes the tilting angle of the hydraulic pump 2 so as to limit the tilting angle to the maximum tilting angle qmax (pump torque limiting control or pump horsepower control).
  • FIG. 3 is a graph showing an absorption torque property of the hydraulic pump 2 acquired as a result of the pump torque limiting control, wherein the horizontal axis represents the discharge pressure Pp of the hydraulic pump 2 and the vertical axis represents the tilting angle (displacement) q of the hydraulic pump 2 .
  • the absorption torque property of the hydraulic pump 2 is made up of a constant maximum tilting angle property line Tp 0 and a constant maximum absorption torque property line Tp 1 .
  • the maximum tilting angle (maximum displacement) qmax of the hydraulic pump 2 remains at a constant value q 0 (which is determined by the mechanism of the hydraulic pump 2 ) even with the increase in the discharge pressure Pp of the hydraulic pump 2 .
  • the maximum absorption torque of the hydraulic pump 2 increases with the increase in the discharge pressure Pp of the hydraulic pump 2 .
  • the maximum tilting angle qmax of the hydraulic pump 2 decreases along the constant maximum absorption torque property line Tp 1 and the absorption torque of the hydraulic pump 2 is kept at maximum torque Tmax which is determined by the property line Tp 1 .
  • This is a control part corresponding to the aforementioned steps S 25 and S 35 .
  • the property line Tp 1 is a part of a hyperbolic curve and the maximum torque Tmax determined by the property line Tp 1 has been set slightly lower than limit torque TEL of the engine 1 .
  • the absorption torque (input torque) of the hydraulic pump 2 is controlled so as not to exceed the preset maximum torque Tmax (so as not to exceed the limit torque TEL of the engine 1 ) by decreasing the maximum tilting angle qmax of the hydraulic pump 2 .
  • the exhaust gas purification system in accordance with this embodiment is installed in such a hydraulic driving system.
  • the exhaust gas purification system comprises an exhaust gas purification device 32 placed in an exhaust line 31 constituting the exhaust system of the engine 1 , an exhaust temperature sensor 33 placed at the inlet of the exhaust gas purification device 32 for detecting the temperature of the exhaust gas inside the exhaust gas purification device, an exhaust resistance sensor 34 for detecting exhaust resistance of a filter inside the exhaust gas purification device 32 , a manual recovery switch 36 used for instructing the exhaust gas purification system (controller 20 ) to start manual recovery control, and an alarm lamp 37 for informing the operator that the a manual recovery process is necessary.
  • Output values of the sensors/switch are inputted to the controller 20 .
  • the exhaust gas purification system further comprises a solenoid proportional valve 38 (pump discharge pressure increasing device) provided in the discharging hydraulic line 2 a of the hydraulic pump 2 .
  • the solenoid proportional valve 38 is a variable throttle valve which changes its opening area according to instruction current supplied to its solenoid.
  • the solenoid proportional valve 38 stays at the full open position shown in the figure when the instruction current is minimum (OFF), decreases the opening area with the increase in the instruction current, and minimizes the opening area (totally closed state) when the instruction current is maximum.
  • the exhaust gas purification device 32 includes the filter, with which particulate matter (PM) contained in the exhaust gas is collected.
  • the exhaust gas purification device 32 is also equipped with an oxidation catalyst. When the exhaust gas temperature exceeds a prescribed temperature, the oxidation catalyst is activated and causes combustion of unburned fuel added to the exhaust gas, an increase in the exhaust gas temperature, and combustion of the collected PM accumulated on the filter.
  • the exhaust gas purification device 32 is equipped with a filter with an oxidation catalyst and another oxidation catalyst placed upstream of the filter, for example.
  • the prescribed temperature (recovery start temperature) for the activation of the oxidation catalyst is approximately 250° C., for example.
  • the exhaust gas purification device 32 may also be implemented by the filter with the oxidation catalyst only.
  • the prescribed temperature (recovery start temperature) for the activation of the oxidation catalyst is approximately 350° C., for example.
  • the exhaust resistance sensor 34 is a differential pressure detecting device for detecting the differential pressure between the upstream side and the downstream side of the filter of the exhaust gas purification device 32 (pressure loss of the filter), for example.
  • FIG. 4 is a schematic diagram showing the external appearance of a hydraulic shovel as an example of the hydraulic operating machine equipped with the hydraulic driving system and the exhaust gas purification system shown in FIG. 1 .
  • the hydraulic shovel comprises a lower travel structure 100 , an upper swing structure 101 and a front work implement 102 .
  • the lower travel structure 100 is equipped with right and left crawler travel devices 103 a and 103 b , which are driven by right and left travel motors 104 a and 104 b , respectively.
  • the upper swing structure 101 is mounted on the lower travel structure 100 so that it can be swiveled by a swing motor 105 .
  • the front work implement 102 is attached to the front part of the upper swing structure 101 so that it can be elevated and lowered.
  • the upper swing structure 101 includes an engine room 106 and a cab 107 .
  • the engine 1 is installed in the engine room 106 .
  • the safety lever (gate lock lever) 12 is placed in the cab 107 at a position close to the entrance to the operator's seat.
  • the control lever devices are arranged to the right and left of the operator's seat.
  • the front work implement 102 is an articulated structure including a boom 111 , an arm 112 and a bucket 113 .
  • the boom 111 is rotated and moved in the vertical direction by the expansion and contraction of a boom cylinder 114 .
  • the arm 112 is rotated and moved in the vertical direction and the front-to-back direction by the expansion and contraction of an arm cylinder 115 .
  • the bucket 113 is rotated and moved in the vertical direction and the front-to-back direction by the expansion and contraction of a bucket cylinder 116 .
  • the hydraulic actuator 25 corresponds to the swing motor 105 , for example, and the control lever device 8 corresponds to one of the control lever devices arranged to the right and left of the operator's seat.
  • Other hydraulic actuators and control valves are not shown in FIG. 1 .
  • FIGS. 5-8 are flow charts showing the contents of a filter recovery calculation process executed by the controller 20 .
  • FIG. 5 shows the overall process flow of automatic recovery control when the hydraulic operating machine (hereinafter referred to simply as a “machine”) is in an operation permission state.
  • FIG. 6 shows the contents of the automatic recovery control when the machine is in the operation permission state and in an operating state (i.e., when the operator is operating the machine).
  • FIG. 7 shows the contents of the automatic recovery control when the machine is in the operation permission state and in a non-operating state (i.e., when the operator is not operating the machine).
  • FIG. 8 shows the contents of the manual recovery control when the machine is in an operation prohibition state.
  • Each of the processes of FIGS. 5-8 is executed repeatedly at preset periods (control cycles).
  • the controller 20 first judges whether the safety lever 12 is at the operation permission position or not by detecting whether the switch 13 operating in conjunction with the safety lever 12 is in the ON state or not (step S 100 ).
  • the switch 13 is in the OFF state, that is, when the safety lever 12 is not at the operation permission position (i.e., at the operation prohibition position)
  • the machine is in the operation prohibition state.
  • the process in the current control cycle is ended without any further processing.
  • the switch 13 is in the ON state, that is, when the safety lever 12 is at the operation permission position, the machine is in the operation permission state. In this case, the process advances to the next step.
  • the controller 20 judges whether any one of the control lever devices is being operated by the operator or not by detecting the output pressures of all the control lever devices (including the control lever device 8 ) based on the output values of the pressure sensor 16 and checking whether each of the output pressures is at a level indicating the operator's operation to a corresponding control lever device or not (step S 200 ).
  • the controller 20 executes automatic recovery control in the operating state (step S 300 ).
  • the controller 20 executes automatic recovery control in the non-operating state (step S 400 ).
  • the controller 20 calculates an exhaust resistance threshold value ⁇ Pa for judging whether the automatic recovery control is necessary or not and sets the calculated exhaust resistance threshold value ⁇ Pa as a first set value (step S 305 ).
  • FIG. 9 is a graph showing the relationship between the amount of PM accumulated on the filter in the exhaust gas purification device 32 and the exhaust resistance of the filter (differential pressure across the filter) at the rated engine revolution speed and the maximum engine load.
  • FIG. 10 is a graph showing changes in the relationship between the PM accumulation amount and the exhaust resistance depending on the engine revolution speed and the engine load.
  • ⁇ PLIMIT represents the exhaust resistance at a limit accumulation amount WLIMIT of the PM (limit exhaust resistance).
  • the limit accumulation amount WLIMIT means an accumulation amount at which further PM accumulation on the filter can cause abnormal combustion.
  • ⁇ Pb represents an exhaust resistance threshold value (second set value) at a PM accumulation amount Wb for judging whether the manual recovery control is necessary or not. This threshold value is set as close to the PM exhaust resistance ⁇ PLIMIT as possible.
  • ⁇ Pc represents an exhaust resistance threshold value at a PM accumulation amount We for judging whether the recovery control should be ended or not.
  • An exhaust resistance threshold value ⁇ Pa at a PM accumulation amount Wa for judging whether the automatic recovery control is necessary or not, has been set at a value lower than the threshold value (second set value) ⁇ Pb for the manual recovery control.
  • the threshold value ⁇ Pa has been set at approximately 40%-60% of the threshold value ⁇ Pb ( ⁇ Pa ⁇ Pb).
  • the relationship between the PM accumulation amount and the exhaust resistance shown in FIG. 9 is that at the rated engine revolution speed and the maximum engine load.
  • the relationship changes depending on the engine revolution speed and the engine load as shown in FIG. 10 .
  • an increase in the engine revolution speed or the engine load causes an increase in the exhaust resistance of the filter since the fuel injection quantity of the electronic governor 1 a increases correspondingly and the flow rate of the exhaust gas increases.
  • a decrease in the engine revolution speed or the engine load causes a decrease in the exhaust resistance of the filter since the fuel injection quantity of the electronic governor 1 a decreases correspondingly and the flow rate of the exhaust gas decreases. Consequently, the relationship between the PM accumulation amount and the exhaust resistance changes as shown in FIG. 10 in response to the increase/decrease in the engine revolution speed or the engine load.
  • the controller 20 previously stores the exhaust resistance threshold value ⁇ Pa (for judging whether the automatic recovery control is necessary or not) as a function of the engine revolution speed and the engine load based on the relationships between the PM accumulation amount and the exhaust resistance like those shown in FIG. 10 .
  • the controller 20 determines the exhaust resistance threshold value ⁇ Pa by referring to the current engine revolution speed and the current engine load and inputting them to the function.
  • the measurement value of the revolution sensor can be used as the current engine revolution speed, and a target fuel injection quantity (as an internal value of the electronic governor 1 a ) can be used as the current engine load. It is also possible to calculate the absorption torque of the hydraulic pump 2 from the tilting angle and the discharge pressure of the hydraulic pump 2 and use the calculated absorption torque as the engine load.
  • an appropriate threshold value ⁇ Pa incorporating the operating status of the engine can be set and the recovery control can be started properly.
  • the controller 20 detects the exhaust resistance ⁇ P of the filter in the exhaust gas purification device 32 based on the output value of the exhaust resistance sensor 34 and then judges whether or not the exhaust resistance ⁇ P is the first set value ⁇ Pa or higher (step S 310 ).
  • the controller 20 ends the process in the current control cycle without any further processing since the PM accumulation has not proceeded to the point at which the filter of the exhaust gas purification device 32 needs the recovery by the automatic recovery control.
  • the exhaust resistance ⁇ P is the first set value ⁇ Pa or higher, the process advances to the next step.
  • the controller 20 starts the automatic recovery control.
  • exhaust gas temperature increasing control is executed (step S 312 ).
  • hydraulic absorption torque increasing control is carried out. Specifically, the discharge pressure of the hydraulic pump 2 is increased by operating the solenoid proportional valve 38 and reducing its opening area. Further, the discharge flow rate of the hydraulic pump 2 is raised by increasing the tilting angle (displacement) of the hydraulic pump 2 .
  • the absorption torque of the hydraulic pump 2 hydroaulic absorption torque
  • the increment of the absorption torque of the hydraulic pump 2 in this case is 20%-30% (preferably, about 30%) of the maximum torque of the engine 1 . With this setting, the engine 1 injects a correspondingly larger amount of fuel, by which the exhaust gas temperature can be increased.
  • FIG. 11 is a flow chart showing the contents of the hydraulic absorption torque increasing control.
  • the controller 20 acquires the target tilting angle qr of the hydraulic pump 2 calculated in the step S 15 in FIG. 2 (step S 50 ).
  • a target tilting angle qco and a target pressure Pco for the hydraulic absorption torque increasing control have previously been set to the controller 20 .
  • the controller 20 compares the target tilting angle qr for the positive control with the target tilting angle qco for the hydraulic absorption torque increasing control (step S 55 ).
  • the controller 20 invalidates the calculation process for the positive control and the pump torque limiting control in the flow chart of FIG. 2 (step S 60 ).
  • the controller 20 calculates a control signal for achieving the target tilting angle qco for the hydraulic absorption torque increasing control and a control signal for achieving the target pressure Pco for the hydraulic absorption torque increasing control, outputs the former control signal to the regulator 14 , and outputs the latter control signal to the solenoid proportional valve 38 (step S 65 ).
  • the controller 20 validates the calculation process for the positive control and the pump torque limiting control in the flow chart of FIG. 2 (step S 70 ).
  • the controller 20 calculates a control signal for achieving the target pressure Pco for the hydraulic absorption torque increasing control and outputs the control signal to the solenoid proportional valve 38 (step S 75 ).
  • the point A is the operating point of the hydraulic pump 2 when the hydraulic absorption torque increasing control is not executed in the non-operating state.
  • the demanded flow rate for the positive control equals 0 and the hydraulic pump 2 is held at a minimum tilting angle qmin (point A).
  • every flow/directional control valve 4 , 5 is at the center valve position shown in the figure and the hydraulic pump 2 remains at a minimum discharge pressure Ppmin (point A).
  • the point B is the operating point of the hydraulic pump 2 when the hydraulic absorption torque increasing control is executed in the non-operating state (explained later).
  • the target tilting angle for the hydraulic absorption torque increasing control is set at qco and the target pressure is set at Pco.
  • the hydraulic absorption torque increasing control is carried out using the target tilting angle qco and the target pressure Pco at the point B.
  • the controller 20 controls the operation amounts of the regulator 14 and the solenoid proportional valve 38 by setting the target tilting angle qco and the target pressure Pco so that the increment of the absorption torque of the hydraulic pump 2 by the hydraulic absorption torque increasing control amounts to 20%-30% (preferably, about 30%) of the maximum torque of the engine 1 .
  • the exhaust gas temperature can be raised to approximately 250° C. when the hydraulic absorption torque is increased by approximately 20% of the maximum engine torque, and to approximately 350° C. when the hydraulic absorption torque is increased by approximately 30% of the maximum engine torque.
  • no problem in terms of operation occurs even if the machine is operated in the state in which the hydraulic absorption torque has been created by the solenoid proportional valve 38 as long as the increment is approximately 30% of the maximum engine torque.
  • the controller 20 judges whether or not the temperature T of the exhaust gas inside the exhaust gas purification device 32 is a preset threshold value Ta or higher based on the output value of the exhaust temperature sensor 33 (step S 315 ). The judgment is repeated unless the exhaust gas temperature T is judged to be the threshold value Ta or higher.
  • the controller 20 starts the recovery control (step S 320 ).
  • the threshold value Ta may be set at, for example, approximately 250° C. (activation temperature of the oxidation catalyst) in the case where the oxidation catalyst is placed upstream of the filter in the exhaust gas purification device 32 . In the case where only the filter with an oxidation catalyst is arranged in the exhaust gas purification device 32 , the threshold value Ta may be set at approximately 350° C. (activation temperature of the oxidation catalyst), for example.
  • post-injection in the expansion stroke after the main injection of the engine is carried out by controlling the electronic governor 1 a of the engine 1 .
  • unburned fuel is introduced into the exhaust gas.
  • the unburned fuel is combusted by the activated oxidation catalyst, by which the exhaust gas temperature is raised and the PM accumulated on the filter is combusted and removed by the high-temperature exhaust gas.
  • the controller 20 calculates and sets the exhaust resistance threshold value ⁇ Pc for judging whether the recovery control should be ended or not (step S 340 ).
  • the idea for the calculation of the threshold value ⁇ Pc is similar to that for the calculation of the threshold value ⁇ Pa. Specifically, the controller 20 previously stores the exhaust resistance threshold value ⁇ Pc (for judging whether the automatic recovery control should be ended or not) as a function of the engine revolution speed and the engine load based on the relationships between the PM accumulation amount and the exhaust resistance like those shown in FIG. 10 .
  • the controller 20 determines the exhaust resistance threshold value ⁇ Pc by referring to the current engine revolution speed and the current engine load and inputting them to the function.
  • the exhaust gas temperature increasing control (hydraulic absorption torque increasing control) and the recovery control (additional fuel injection) are executed until the exhaust resistance ⁇ P of the exhaust gas purification device 32 falls below the threshold value ⁇ Pc.
  • the controller 20 ends the automatic recovery control, puts the solenoid proportional valve 38 in the full open state by stopping activating the valve, and thereby ends the exhaust gas temperature increasing control (hydraulic absorption torque increasing control) and the recovery control (additional fuel injection) (steps S 320 , S 340 , S 345 and S 350 ).
  • a hydraulic operating machine (hydraulic shovel) is generally equipped with an automatic idling function.
  • the automatic idling function is a technique for reducing the engine revolution speed to an idling revolution speed a prescribed time period (e.g., 5 seconds) after the control lever 8 c of the control lever device 8 is returned from its operating position to its neutral position.
  • a prescribed time period e.g. 5 seconds
  • the hydraulic absorption torque increasing control and an engine revolution speed increasing control are executed in the exhaust gas temperature increasing control (step S 412 ).
  • the increment of the absorption torque of the hydraulic pump 2 in the hydraulic absorption torque increasing control is 20%-30% (preferably, about 30%) of the maximum torque of the engine 1 similarly to the case in the operating state.
  • the engine revolution speed increasing control the engine revolution speed is increased to approximately 1700 rpm, for example.
  • FIG. 12 is a flow chart showing the contents of a process including the hydraulic absorption torque increasing control and the engine revolution speed increasing control executed in the step S 412 in FIG. 7 .
  • the controller 20 calculates the aforementioned control signal for achieving the target tilting angle qco for the hydraulic absorption torque increasing control and the aforementioned control signal for achieving the target pressure Pco for the hydraulic absorption torque increasing control, outputs the former control signal to the regulator 14 , and outputs the latter control signal to the solenoid proportional valve 38 (step S 80 ).
  • the hydraulic pump 2 operates at the operating point B shown in FIG. 3 .
  • the controller 20 also executes the engine revolution speed increasing control so as to increase the engine revolution speed to approximately 1700 rpm (step S 85 ).
  • steps S 405 , S 410 , S 415 , S 420 , S 440 , S 445 and S 450 are executed in the same way as the steps S 305 , S 310 , S 315 , S 320 , S 340 , S 345 and S 350 in FIG. 6 .
  • the exhaust resistance threshold value (first set value) used for starting the automatic recovery control in the non-operating state may be set lower than the threshold value ⁇ Pa which is used for starting the automatic recovery control in the operating state.
  • the threshold value set lower than ⁇ Pa is expressed as “ ⁇ Pd” in parentheses ( ⁇ Pd ⁇ Pa).
  • the threshold value ⁇ Pd is indicated in FIG. 9 as the exhaust resistance at a PM accumulation amount Wd.
  • the increment of the absorption torque of the hydraulic pump 2 (hydraulic absorption torque) in the hydraulic absorption torque increasing control in the step S 412 may be set greater than 30% of the maximum engine torque (the increment in the operating state) since no problem occurs even if the absorption torque of the hydraulic pump 2 is increased greatly in the non-operating state. With such a setting, the speed of the exhaust gas temperature increasing control in the non-operating state can be increased and the filter recovery process can be performed quickly.
  • the controller 20 detects the exhaust resistance ⁇ P of the exhaust gas purification device 32 based on the output value of the exhaust resistance sensor 34 and then judges whether or not the exhaust resistance ⁇ P is the second set value ⁇ Pb (previously set as the exhaust resistance threshold value for judging whether the manual recovery control is necessary or not) or higher (step S 500 ). Since the engine revolution speed and the engine load are controlled at substantially constant levels in the manual recovery control (as will be explained later), the exhaust resistance threshold value for judging whether the manual recovery control is necessary or not may be previously determined and set as a fixed value as an exhaust resistance value corresponding to the constant engine revolution speed and the constant engine load. The same goes for the exhaust resistance threshold value ⁇ Pc (for judging whether the recovery control should be ended or not) which will be explained later.
  • the second set value ⁇ Pb has been set to satisfy the relationship ⁇ Pa ⁇ Pb with the first set value ⁇ Pa and to be as close to the exhaust resistance ⁇ PLIMIT at the limit PM accumulation amount WLIMIT as possible.
  • the controller 20 ends the process in the current control cycle without any further processing since the PM accumulation has not proceeded to the point at which the filter of the exhaust gas purification device 32 needs the recovery by the manual recovery control.
  • the exhaust resistance ⁇ P is the second set value ⁇ Pb or higher, the process advances to the next step.
  • the controller 20 lights up the alarm lamp 37 and thereby informs the operator that the manual recovery process is necessary (step S 510 ).
  • the controller 20 judges whether the safety lever 12 is at the operation prohibition position or not by detecting whether the switch 13 operating in conjunction with the safety lever 12 is in the OFF state or not (step S 520 ).
  • the switch 13 is in the ON state, that is, when the safety lever 12 is not at the operation prohibition position (i.e., at the operation permission position)
  • the machine is in the operation permission state.
  • the machine is in a state unsuitable for the manual recovery control, and thus the controller 20 ends the process in the current control cycle without any further processing.
  • the switch 13 is in the OFF state, that is, when the safety lever 12 is at the operation prohibition position, the machine is in the operation prohibition state. In this case, the process advances to the next step.
  • step S 530 the controller 20 judges whether the manual recovery switch 36 has been turned ON or not.
  • the controller 20 ends the process in the current control cycle without any further processing.
  • the process advances to the next step.
  • the controller 20 extinguishes the alarm lamp 37 (step S 540 ) and executes the exhaust gas temperature increasing control by performing the hydraulic absorption torque increasing control and the engine revolution speed increasing control (step S 545 ) similarly to the automatic recovery control shown in FIG. 7 .
  • the engine 1 is necessarily in the idling revolution state since the safety lever is at the operation prohibition position, the pilot cut valve 11 has been closed and the machine is in an inoperable state (in which operation to the machine is impossible). Therefore, in the step S 545 , the increase in the exhaust gas temperature is promoted by executing the hydraulic absorption torque increasing control (20%-30% (preferably, about 30%) of the maximum torque of the engine 1 ) and the engine revolution speed increasing control (approximately 1700 rpm, for example) similarly to the step S 412 in the automatic recovery control in the non-operating state shown in FIG. 7 .
  • the increment of the absorption torque of the hydraulic pump 2 (hydraulic absorption torque) in the hydraulic absorption torque increasing control in the step S 545 may be set greater than 30% of the maximum engine torque (the increment in the operating state). With such a setting, the speed of the exhaust gas temperature increasing control in cases where the machine is in the inoperable state can be increased and efficient recovery control of the filter becomes possible.
  • the solenoid proportional valve 38 forms a pump discharge pressure increasing device which is provided in the hydraulic line 2 a (through which the hydraulic fluid discharged from the hydraulic pump 2 flows) and increases the discharge pressure of the hydraulic pump 2 .
  • the processing function of the controller 20 in the steps S 305 -S 350 in FIG. 6 , the steps S 405 -S 450 in FIG. 7 and the steps S 500 -S 610 in FIG. 8 forms a recovery control device which executes the recovery of the exhaust gas purification device 32 by combusting and removing the particulate matter accumulated in the exhaust gas purification device 32 when the exhaust resistance detected by the exhaust resistance sensor 34 has reached or exceeded the set value ⁇ Pa or ⁇ Pb.
  • the processing function of the controller 20 in the steps S 312 and S 315 in FIG. 6 , the steps S 412 and S 415 in FIG. 7 and the steps S 545 and S 550 in FIG. 8 forms an exhaust temperature increasing control device which increases the exhaust gas temperature so as to make the exhaust gas temperature detected by the exhaust temperature sensor 33 reach a preset value by increasing the absorption torque of the hydraulic pump 2 by operating at least the latter one (solenoid proportional valve 38 ) of the regulator 14 (pump displacement adjusting device) and the solenoid proportional valve 38 (pump discharge pressure increasing device) when the exhaust resistance detected by the exhaust resistance sensor 34 has reached or exceeded the set value ⁇ Pa or ⁇ Pb.
  • the exhaust temperature increasing control device controls at least the operation amount of the solenoid proportional valve 38 so that the increment of the absorption torque of the hydraulic pump 2 amounts to 20%-30% of the maximum torque of the engine 1 .
  • the processing function of the controller 20 in the steps S 305 -S 350 in FIG. 6 and the steps S 405 -S 450 in FIG. 7 forms an automatic recovery control device which automatically starts operation when the exhaust resistance detected by the exhaust resistance sensor 34 has reached or exceeded the set value ⁇ Pa.
  • the switch 13 forms operation permission state detecting means which detects whether the hydraulic operating machine is in the operation permission state or not.
  • the manual recovery switch 36 forms manual recovery instruction means.
  • the manual recovery instruction means and the processing function of the controller 20 in the steps S 500 -S 610 in FIG. 8 form a manual recovery control device which issues an alarm when the exhaust resistance detected by the exhaust resistance sensor 34 has reached or exceeded the set value ⁇ Pb and starts operation when the switch 13 (operation permission state detecting means) detects that the hydraulic operating machine is not in the operation permission state and there is an instruction by (received through) the manual recovery switch 36 (manual recovery instruction means).
  • the exhaust gas temperature is increased by operating the solenoid proportional valve 38 so that the exhaust gas temperature as the output value of the exhaust temperature sensor 33 reaches the preset value Ta. Therefore, the recovery process of the exhaust gas purification device can be executed with reliability by increasing the exhaust gas temperature irrespective of the operating environment and economic efficiency can be improved by keeping the fuel consumption at a minimum necessary level.
  • the present inventors have confirmed that the exhaust gas temperature can be increased to approximately 250° C.-350° C. without causing any problem to the operation of the hydraulic operating machine driving hydraulic actuators if the hydraulic absorption torque generated by a hydraulic absorption torque increasing device is approximately 20%-30% of the aforementioned maximum engine torque.
  • the solenoid proportional valve 38 By controlling the operation amount of the solenoid proportional valve 38 so that the increment of the absorption torque of the hydraulic pump 2 amounts to 20%-30% of the maximum torque of the engine 1 , unnecessary and excessive increase in the exhaust gas temperature can be avoided, the fuel consumption can be kept at a minimum necessary level, and the economic efficiency can be improved.
  • the filter recovery process can be performed by increasing the exhaust gas temperature without causing any problem to the operation of the machine. Consequently, working efficiency can be increased through the improvement of workability during the execution of the recovery control and the reduction of the operation interruption frequency of the machine.
  • the filter recovery process can be performed reliably by increasing the exhaust gas temperature and the fuel consumption can be kept at a minimum necessary level irrespective of the operating environment.
  • the exhaust resistance set value in the automatic recovery control for cases where the hydraulic actuator 25 is not being driven is set at the value ⁇ Pd lower than the exhaust resistance set value ⁇ Pa for cases where the hydraulic actuator 25 is being driven.
  • the following effect is achieved: In the non-operating state (i.e., when no hydraulic actuator is being driven) in which the exhaust gas temperature is relatively low and the particulate matter (PM) tends to accumulate relatively more, the PM accumulated on the filter of the exhaust gas purification device 32 can be combusted more frequently than in the operating state (i.e., when a hydraulic actuator is being driven) and the filter of the exhaust gas purification device 32 can be recovered efficiently.
  • the frequency of the automatic recovery control increases and the frequency of the manual recovery control decreases due to the output value of the exhaust resistance sensor 34 increasing to the set value ⁇ Pb less frequently. This also contributes to the reduction of the operation interruption frequency of the hydraulic operating machine.
  • the exhaust resistance threshold value ⁇ Pa for judging whether the automatic recovery control is necessary or not and the exhaust resistance threshold value ⁇ Pc for judging whether the recovery control should be ended or not are determined and set through the aforementioned calculation. Therefore, appropriate threshold values ⁇ Pa and ⁇ Pc incorporating the operating status of the engine can be set and the recovery control can be executed properly.
  • FIGS. 13-16 A second embodiment in accordance with the present invention will be described below with reference to FIGS. 13-16 .
  • the pump torque control is executed directly by the regulator without using the controller.
  • FIG. 13 is a schematic diagram showing a hydraulic driving system of a hydraulic operating machine equipped with an exhaust gas purification system in accordance with the second embodiment, wherein elements equivalent to those shown in FIG. 1 are assigned the same reference characters.
  • the hydraulic driving system of this embodiment is equipped with a controller 20 A, a regulator 14 A to which the discharge pressure of the hydraulic pump 2 is lead via a hydraulic line 41 , and a solenoid proportional valve 42 which operates according to a control signal from the controller 20 A and outputs control pressure specifying the target tilting angle qr of the hydraulic pump 2 to the regulator 14 A.
  • the controller 20 A detects the operation amount of the control lever device 8 and the engine revolution speed at that time with the pressure sensor 16 and the revolution sensor 18 , respectively, calculates the target tilting angle of the hydraulic pump 2 through a calculation process for the positive control, and outputs a control signal to the solenoid proportional valve 42 so that the target tilting angle is achieved.
  • the solenoid proportional valve 42 outputs control pressure corresponding to the control signal.
  • the regulator 14 A changes the tilting angle of the hydraulic pump 2 according to the control pressure.
  • FIG. 14 is a flow chart showing the contents of a calculation process for the positive control of the hydraulic pump 2 executed by the controller 20 A, wherein steps identical with those in FIG. 2 are assigned the same reference characters.
  • the controller 20 A in this embodiment is configured to execute only the steps S 10 , S 15 and S 30 related to the positive control.
  • the controller 20 A outputs the control signal for achieving the target tilting angle qr to the solenoid proportional valve 42 .
  • the regulator 14 A is configured to execute the positive control based on the output pressure (control pressure) of the solenoid proportional valve 42 while also executing the pump torque control by itself based on the discharge pressure of the hydraulic pump 2 supplied via the hydraulic line 41 . Specifically, when the control pressure outputted by the solenoid proportional valve 42 changes, the regulator 14 A controls the tilting angle of the hydraulic pump 2 so that the target tilting angle qr specified by the control pressure is achieved (positive control).
  • the regulator 14 A controls the tilting angle of the hydraulic pump 2 so as to limit the tilting angle to the maximum tilting angle qmax (pump torque limiting control or pump horsepower control).
  • a regulator 14 A is publicly known.
  • FIG. 15 is a graph like FIG. 3 showing the absorption torque property of the hydraulic pump 2 acquired as a result of the pump torque limiting control, wherein the horizontal axis represents the discharge pressure Pp of the hydraulic pump 2 and the vertical axis represents the tilting angle (displacement) q of the hydraulic pump 2 .
  • the absorption torque property of the hydraulic pump 2 is made up of a constant maximum tilting angle property line Tp 0 and constant maximum absorption torque property lines Tp 2 and Tp 3 .
  • the control of the tilting angle of the hydraulic pump 2 when the discharge pressure P of the hydraulic pump 2 is under the first value P 0 (on the constant maximum tilting angle property line Tp 0 ) is identical with that in FIG. 3 .
  • the maximum tilting angle qmax of the hydraulic pump 2 decreases along the constant maximum absorption torque property lines Tp 2 and Tp 3 and the absorption torque of the hydraulic pump 2 is kept at maximum torque Tmax which is determined by the property lines Tp 2 and Tp 3 .
  • the constant maximum absorption torque property lines Tp 2 and Tp 3 have been set based on two springs installed in the regulator 14 A. Each property line Tp 2 , Tp 3 is in a shape imitating a hyperbolic curve.
  • the maximum torque Tmax determined by the property lines Tp 2 and Tp 3 has been set slightly lower than limit torque TEL of the engine 1 . With this setting, when the discharge pressure P of the hydraulic pump 2 increases over the first value P 0 , the absorption torque (input torque) of the hydraulic pump 2 is controlled so as not to exceed the preset maximum torque Tmax (so as not to exceed the limit torque TEL of the engine 1 ) by decreasing the maximum tilting angle qmax of the hydraulic pump 2 .
  • FIG. 16 is a flow chart showing the details of the hydraulic absorption torque increasing control in the step S 312 in FIG. 6 regarding the automatic recovery control in the operating state, wherein steps identical with those in FIG. 11 are assigned the same reference characters.
  • the calculation process for the positive control executed by the controller 20 A is invalidated in step S 60 A and validated in step S 70 A since the controller 20 A in this embodiment executes the calculation process for the positive control only.
  • the details of the hydraulic absorption torque increasing control in the step S 412 in FIG. 7 regarding the automatic recovery control in the non-operating state and the details of the hydraulic absorption torque increasing control in the step S 545 in FIG. 8 regarding the manual recovery control executed when the machine is in the operation prohibition state are no different from those in FIG. 12 in the first embodiment.
  • FIG. 17 is a flow chart showing the contents of the automatic recovery control in the operating state.
  • FIG. 18 is a flow chart showing the contents of the automatic recovery control in the non-operating state.
  • FIG. 19 is a flow chart showing the contents of the manual recovery control when the hydraulic operating machine is in the operation prohibition state.
  • FIGS. 17-19 correspond to FIGS. 6-8 in the first embodiment, respectively.
  • the exhaust gas temperature T is adjusted to be within a prescribed temperature range with respect to the threshold value Ta even after the exhaust gas temperature T has reached/exceeded the threshold value Ta due to the exhaust gas temperature increasing control, by meticulously performing the hydraulic absorption torque increasing control and/or the engine revolution speed increasing control.
  • the controller 20 A judges whether the exhaust gas temperature T in the exhaust gas purification device 32 is within a preset temperature range between reference temperatures Ta 1 and Ta 2 or not based on the output value of the exhaust temperature sensor 33 (step S 365 ).
  • the controller 20 A starts the recovery control (additional fuel injection) (step S 320 ).
  • the controller 20 A adjusts the torque increment of the hydraulic absorption torque increasing control (step S 370 ) and repeats the torque increment adjustment until the exhaust gas temperature T comes within the preset temperature range (step S 365 ⁇ S 370 ).
  • the reference temperatures Ta 1 and Ta 2 specifying the preset temperature range satisfy a relationship Ta 1 ⁇ Ta 2 .
  • the reference temperature Ta 1 may be set equal to the threshold value Ta in the first and second embodiments, for example.
  • the reference temperature Ta 2 is set slightly (e.g., 5° C.-50° C. (preferably, about 10° C.-30° C.)) higher than Ta 1 .
  • the torque increment adjustment in the hydraulic absorption torque increasing control is made by increasing/decreasing at least one of the target tilting angle qco and the target pressure Pco for the hydraulic absorption torque increasing control by a prescribed amount when the target tilting angle qr for the positive control is less than or equal to the target tilting angle qco for the hydraulic absorption torque increasing control.
  • the torque increment adjustment in the hydraulic absorption torque increasing control is made by increasing/decreasing the target pressure Pco for the hydraulic absorption torque increasing control by a prescribed amount in order to avoid ill effect on the positive control.
  • the operation amount of the regulator 14 is controlled and the tilting angle (displacement) of the hydraulic pump 2 is adjusted.
  • the operation amount (opening area) of the solenoid proportional valve 38 is controlled and the discharge pressure of the hydraulic pump 2 is adjusted. Therefore, by increasing/decreasing at least one of the target tilting angle qco and the target pressure Pco by a prescribed amount, the absorption torque of the hydraulic pump 2 is controlled and the engine load is increased/decreased, by which the exhaust gas temperature can be adjusted.
  • the torque increment adjustment in the hydraulic absorption torque increasing control in the steps S 470 and S 670 may be made constantly by increasing/decreasing at least one of the target tilting angle qco and the target pressure Pco for the hydraulic absorption torque increasing control by a prescribed amount.
  • the adjustment of the exhaust gas temperature described above may be made also by increasing/decreasing the engine revolution speed in the engine revolution speed increasing control in combination with or in place of the torque increment adjustment in the hydraulic absorption torque increasing control.
  • the processing function of the controller 20 A in the steps S 305 -S 350 , S 365 and S 370 in FIG. 17 , the steps S 405 -S 450 , S 465 and S 470 in FIG. 18 , and the steps S 500 -S 610 , S 665 and S 670 in FIG. 19 forms a recovery control device which executes the recovery of the exhaust gas purification device 32 by combusting and removing the particulate matter accumulated in the exhaust gas purification device 32 when the exhaust resistance detected by the exhaust resistance sensor 34 has reached or exceeded the set value ⁇ Pa or ⁇ Pb.
  • the processing function of the controller 20 A in the steps S 312 , S 365 and S 370 in FIG. 17 , the steps S 412 , S 465 and S 470 in FIG. 18 and the steps S 545 , S 665 and S 670 in FIG. 19 forms an exhaust temperature increasing control device which increases the exhaust gas temperature so as to make the exhaust gas temperature detected by the exhaust temperature sensor 33 reach a preset value by increasing the absorption torque of the hydraulic pump 2 by operating at least the latter one (solenoid proportional valve 38 ) of the regulator 14 (pump displacement adjusting device) and the solenoid proportional valve 38 (pump discharge pressure increasing device) when the exhaust resistance detected by the exhaust resistance sensor 34 has reached or exceeded the set value ⁇ Pa or ⁇ Pb.
  • the steps S 365 and S 370 ( FIG. 17 ), the steps S 465 and S 470 ( FIG. 18 ) and the steps S 665 and S 670 ( FIG. 19 ) form an exhaust temperature adjusting device which adjusts at least one selected from the operation amount of the regulator 14 or 14 A (pump displacement adjusting device), the operation amount of the solenoid proportional valve 38 (pump discharge pressure increasing device) and the increment of the engine revolution speed so that the exhaust gas temperature remains within a preset range Ta 1 -Ta 2 after the exhaust gas temperature detected by the exhaust temperature sensor 33 has been increased to the preset value Ta 1 .
  • the torque increment in the hydraulic absorption torque increasing control and/or the increment of the engine revolution speed in the engine revolution speed increasing control is finely adjusted so that the exhaust gas temperature T remains within the preset temperature range. Therefore, the exhaust gas temperature T can be reliably controlled and kept within the preset temperature range. Consequently, ill effect on the operation can be minimized in the recovery control in the operating state. In the recovery control in the non-operating state, unnecessary increase in the engine load can be avoided and the fuel consumption can be kept at a minimum necessary level irrespective of the operating environment, by which the economic efficiency can be improved further.
  • the fuel injection for the recovery control in the above embodiments is executed by means of the post-injection (additional injection) in the expansion stroke after the main injection of the engine
  • the fuel injection for the recovery control may also be carried out by providing the exhaust line with an extra fuel injection device for the recovery control and operating the fuel injection device.
  • the hydraulic absorption torque increasing control in the above embodiments is executed by providing the solenoid proportional valve 38 (for exerting the load for increasing the exhaust gas temperature on the engine in the recovery control) in the discharging hydraulic line 2 a of the hydraulic pump 2 and controlling the operation amount (opening area) of the solenoid proportional valve 38
  • the solenoid proportional valve 38 may also be placed at the downstream end of a center bypass hydraulic line penetrating the flow/directional control valve 4 .
  • the exertion of the load on the engine may also be implemented by use of different means.

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IN2012DN01607A (enrdf_load_stackoverflow) 2015-06-05
KR20120117975A (ko) 2012-10-25
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EP2530266A1 (en) 2012-12-05
JPWO2011093400A1 (ja) 2013-06-06

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