JP2015148182A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine capable of stably determining a clogging state of an oxidation catalyst caused by adhesion of a soot component.SOLUTION: An exhaust emission control device 18 includes an oxidation catalyst 20. A pressure sensor 23 for detecting a pressure P1 on an inlet side and a pressure sensor 24 for detecting a pressure P2 on an outlet side are respectively provided on the inlet side and the outlet side of the oxidation catalyst 20. A controller 26 determines whether the oxidation catalyst 20 is in the clogging state caused by adhesion of a soot component or not based on the pressures P1 and P2 detected by the pressure sensors 23 and 24. The controller 26 executes fail-safe control for informing an operator that the oxidation catalyst 20 is in the clogging state through an alarm 25 when it is determined that the oxidation catalyst 20 is in the clogging state.

Description

  The present invention relates to a construction machine equipped with an exhaust gas treatment device that is preferably used to remove harmful substances from exhaust gas such as diesel engines.

  In general, a construction machine such as a hydraulic excavator or a hydraulic crane is capable of a self-propelled lower traveling body, an upper revolving body that is turnably mounted on the lower traveling body, and an up-and-down movable forward of the upper revolving body. And a working device provided. The upper swing body has an engine for driving a hydraulic pump on the rear side of the swing frame forming the support structure, and a cab, a fuel tank, a hydraulic oil tank, and the like are mounted on the front side of the swing frame.

  Here, a diesel engine is generally used as an engine serving as a prime mover for construction machinery. The exhaust gas discharged from such a diesel engine may contain harmful substances such as particulate matter (PM) and nitrogen oxide (NOx). For this reason, in a construction machine, an exhaust gas treatment device for purifying exhaust gas is provided in an exhaust pipe that forms an exhaust gas passage of the engine.

  The exhaust gas treatment device is an oxidation catalyst (for example, Diesel Oxidation Catalyst, DOC for short) that oxidizes and removes nitrogen monoxide (NO), carbon monoxide (CO), hydrocarbon (HC), etc. contained in the exhaust gas. And a particulate matter removal filter (for example, Diesel Particulate Filter, abbreviated as DPF for short) that is disposed downstream of the oxidation catalyst and collects and removes particulate matter in the exhaust gas. (Patent Document 1).

  Here, the particulate matter is deposited on the particulate matter removal filter as the particulate matter is collected, thereby clogging the filter. For this reason, it is necessary to remove the particulate matter deposited on the filter and regenerate the filter. The regeneration of the filter can be performed by burning the particulate matter deposited on the filter. In this case, the oxidation reaction via the oxidation catalyst and the load applied to the engine increase, so that the temperature of the exhaust gas rises, so that the particulate matter deposited on the filter can be combusted (low temperature regeneration). . Further, by performing fuel injection for regeneration called post-injection, the temperature of the exhaust gas can be raised and the particulate matter deposited on the filter can be forcibly burned (high temperature regeneration).

JP 2008-274835 A

  By the way, the prior art by patent document 1 becomes a structure which determines degradation of the oxidation catalyst which comprises an exhaust-gas processing apparatus based on the fuel injection amount of an engine. However, in this configuration, for example, when the engine fuel injection device (injector) is malfunctioning, or when the filter regeneration process is malfunctioning, there is a possibility that the deterioration of the oxidation catalyst cannot be determined. is there.

  The present invention has been made in view of the above-described problems of the prior art, and provides a construction machine that can stably perform the determination of the deterioration of the oxidation catalyst, in particular, the determination of the closed state of the oxidation catalyst due to adhesion of soot components. The purpose is that.

  The construction machine of the present invention includes a frame forming a support structure, an engine mounted on the frame, and an oxidation catalyst for oxidizing components in exhaust gas discharged from the engine. And an exhaust gas treatment device provided on the exhaust side.

  In order to solve the above-described problems, the configuration of the invention of claim 1 is characterized in that the inlet side pressure detecting means for detecting the pressure (P1) on the inlet side of the oxidation catalyst, and the outlet of the oxidation catalyst Of the soot component of the oxidation catalyst based on the pressure (P1, P2) detected by the outlet side pressure detecting means for detecting the side pressure (P2) and the inlet side pressure detecting means and the outlet side pressure detecting means. An oxidation catalyst blockage determination unit that determines whether or not the blockage is caused by adhesion, and a failsafe control that performs failsafe control when the oxidation catalyst blockage determination unit determines that the oxidation catalyst is in a blockage state And means for providing the means.

  The invention of claim 2 comprises an inlet side temperature detecting means for detecting the temperature (T1) on the inlet side of the oxidation catalyst, and an outlet side temperature detecting means for detecting the temperature (T2) on the outlet side of the oxidation catalyst. The oxidation catalyst blockage determination unit is configured to block the oxidation catalyst based on the temperature (T1, T2) and the pressure (P1, P2) detected by the inlet side temperature detection unit and the outlet side temperature detection unit. The state is determined.

  According to a third aspect of the present invention, the exhaust gas treatment device has a filter that is located downstream of the oxidation catalyst and collects particulate matter in the exhaust gas discharged from the engine in addition to the oxidation catalyst. It is in the configuration.

  According to a fourth aspect of the present invention, there is provided filter outlet side pressure detecting means for detecting the pressure (P3) on the outlet side of the filter, and the oxidation catalyst blockage determining means is the pressure detected by the filter outlet side pressure detecting means. The blockage state of the oxidation catalyst is determined based on (P3) and the pressures (P1, P2).

  According to the first aspect of the present invention, the oxidation catalyst blockage determination means can determine whether or not the oxidation catalyst is blocked, that is, whether or not the oxidation catalyst blockage is caused by the adhesion of soot components. In this case, the oxidation catalyst blockage determination means is based on the pressures (P1, P2) on the inlet side (upstream side) and outlet side (downstream side) of the oxidation catalyst detected by the inlet side pressure detection means and the outlet side pressure detection means. To make a decision. More specifically, depending on whether or not the differential pressure (ΔP = P1−P2) between the pressure on the inlet side (P1) and the pressure on the outlet side (P2) is greater than or equal to a preset differential pressure threshold (Pt), It can be determined whether or not the oxidation catalyst is in a closed state.

  Therefore, for example, even when the engine fuel injection device (injector) malfunctions or when the filter regeneration process malfunctions, the determination of the blocking state of the oxidation catalyst by the oxidation catalyst blocking determination unit is stably performed. It can be carried out. In addition, the determination of the blocked state of the oxidation catalyst can be performed as a simple process without requiring a complicated determination process.

  In addition, when the oxidation catalyst blockage determination unit determines that the oxidation catalyst is in the blockage state, the failsafe control unit notifies the operator (driver) of the fact, for example, or operates the engine (rotation speed or Output) can be limited. Thereby, when the oxidation catalyst is in a closed state, the operator can perform necessary maintenance such as inspection, repair, and replacement of the oxidation catalyst. Further, even when maintenance is not performed, the engine operation is restricted, so that the engine can be protected and exhaust gas that is not sufficiently oxidized can be prevented from being discharged.

  According to the invention of claim 2, the oxidation catalyst blockage determination means includes the inlet side temperature detection means and the outlet in addition to the pressure (P1, P2) on the inlet side (upstream side) and outlet side (downstream side) of the oxidation catalyst. The closed state of the oxidation catalyst is determined using also the temperatures (T1, T2) on the inlet side (upstream side) and outlet side (downstream side) of the oxidation catalyst detected by the side temperature detection means. In this case, whether or not the temperature difference (ΔT = T2−T1), which is the difference between the inlet side temperature (T1) and the outlet side temperature (T2), is equal to or less than a preset temperature difference threshold (Tt), It can be determined whether or not the oxidation activity state of the oxidation catalyst is lowered. Therefore, the determination of the blocked state of the oxidation catalyst can be performed in consideration of the oxidation active state of the oxidation catalyst, and the blocked state of the oxidation catalyst can be determined more finely (with high accuracy).

  According to the invention of claim 3, in the exhaust gas processing apparatus configured to include the filter and the oxidation catalyst, it is possible to stably determine the closed state of the oxidation catalyst.

  According to the invention of claim 4, the oxidation catalyst blockage judging means includes the pressure (P1) on the inlet side (upstream side) of the oxidation catalyst and the inlet side (upstream side) of the filter on the outlet side (downstream side) of the oxidation catalyst. The blocking state of the oxidation catalyst is determined based on the pressure (P2) and the pressure (P3) on the outlet side (downstream side) of the filter. For this reason, in the exhaust gas treatment device configured to include the filter and the oxidation catalyst, it is possible to improve the accuracy (accuracy) of determining the closed state of the oxidation catalyst.

It is a front view which shows the hydraulic shovel applied to the 1st Embodiment of this invention. FIG. 2 is a partially cutaway plan view showing the hydraulic excavator in an enlarged manner with the cab and part of the outer cover removed from the upper swing body in FIG. 1. It is a circuit block diagram which shows an engine, an exhaust-gas processing apparatus, a controller, etc. It is a flowchart which shows the process by the controller in FIG. It is a circuit block diagram which shows the engine, exhaust gas processing apparatus, controller, etc. by 2nd Embodiment. It is a flowchart which shows the process by the controller in FIG. It is a circuit block diagram which shows the engine, exhaust gas processing apparatus, controller, etc. by 3rd Embodiment. It is a flowchart which shows the process by the controller in FIG.

  Hereinafter, a construction machine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the construction machine is applied to a small hydraulic excavator called a mini excavator.

  1 to 4 show a first embodiment of the present invention. In the figure, 1 is a small hydraulic excavator used for excavation work of earth and sand. The hydraulic excavator 1 is a self-propelled crawler-type lower traveling body 2, and is mounted on the lower traveling body 2 through a turning device 3 so as to be capable of turning. The main body 4 and a work device 5 provided so as to be able to move up and down on the front side of the upper swing body 4 are roughly configured.

  Here, the working device 5 is configured as a swing post type working device, for example, a swing post 5A, a boom 5B, an arm 5C, a bucket 5D as a working tool, and a swing cylinder 5E that swings the working device 5 left and right. (Refer to FIG. 2), a boom cylinder 5F, an arm cylinder 5G, and a bucket cylinder 5H are provided. The upper swing body 4 includes a swing frame 6, an exterior cover 7, a cab 8, and a counterweight 9 which will be described later.

  The turning frame 6 is a frame that forms a support structure of the upper turning body 4, and the turning frame 6 is mounted on the lower traveling body 2 via the turning device 3. The revolving frame 6 is provided with a counterweight 9 and an engine 10 which will be described later on the rear side, a cab 8 which will be described later on the left front side, and a fuel tank 16 which will be described later on the right front side. The revolving frame 6 is provided with an exterior cover 7 extending from the right side to the rear side of the cab 8, and this exterior cover 7 together with the revolving frame 6, the cab 8 and the counterweight 9, the engine 10, the hydraulic pump 15, and the heat exchanger 17. A space for accommodating the exhaust gas treatment device 18 and the like is defined.

  The cab 8 is mounted on the left front side of the revolving frame 6, and the cab 8 defines an operator cab in which an operator (driver) is boarded. Inside the cab 8, a driver's seat on which an operator is seated, various operation levers (all not shown), and the like are arranged.

  The counterweight 9 balances the weight of the work device 5, and the counterweight 9 is attached to the rear end portion of the turning frame 6 so as to be positioned on the rear side of the engine 10 described later. As shown in FIG. 2, the rear surface side of the counterweight 9 is formed in an arc shape, and the counterweight 9 is configured to fit within the vehicle body width of the lower traveling body 2.

  Reference numeral 10 denotes an engine that is disposed horizontally on the rear side of the revolving frame 6. Since the engine 10 is mounted as a prime mover on the small hydraulic excavator 1, for example, a small diesel engine is used. The engine 10 is provided with an intake pipe 11 (see FIG. 3) for sucking outside air and an exhaust pipe 12 forming a part of an exhaust gas passage for discharging exhaust gas. The intake pipe 11 is for the outside air (air) to flow toward the engine 10, and an air cleaner 13 for cleaning the outside air is connected to the front end side of the intake pipe 11. The exhaust pipe 12 is provided with an exhaust gas processing device 18 to be described later.

  Here, the engine 10 is composed of an electronically controlled engine, and the amount of fuel supplied is variably controlled by a fuel injection device 14 (see FIG. 3) such as an electronically controlled injection valve. That is, the fuel injection device 14 variably controls the injection amount (fuel injection amount) of fuel injected into a cylinder (not shown) of the engine 10 based on a control signal output from the controller 26 described later. As a result, the engine 10 is configured such that its rotational speed and output are controlled by the controller 26. For example, when it is determined by the controller 26 that the oxidation catalyst 20 of the exhaust gas processing device 18 to be described later is closed, the fuel injected from the fuel injection device 14 based on the command from the controller 26 is normal. Therefore, the fail-safe control for limiting the rotation speed and output of the engine 10 can be performed.

  The hydraulic pump 15 is attached to the left side of the engine 10, and the hydraulic pump 15 constitutes a hydraulic source together with a hydraulic oil tank (not shown). The hydraulic pump 15 discharges pressure oil (hydraulic oil) toward a control valve (not shown) by being driven by the engine 10. The hydraulic pump 15 is configured by, for example, a variable displacement swash plate type, a swash shaft type, or a radial piston type hydraulic pump. The hydraulic pump 15 is not necessarily limited to a variable displacement hydraulic pump, and may be configured using, for example, a fixed displacement hydraulic pump.

  The fuel tank 16 is located on the right side of the cab 8 and is provided on the revolving frame 6 and is covered with the exterior cover 7 together with a hydraulic oil tank (not shown). The fuel tank 16 is formed as, for example, a substantially rectangular parallelepiped pressure-resistant tank, and stores fuel supplied to the engine 10.

  The heat exchanger 17 is provided on the turning frame 6 on the right side of the engine 10, and the heat exchanger 17 includes, for example, a radiator, an oil cooler, and an intercooler. That is, the heat exchanger 17 cools the cooling water of the engine 10 and also cools the pressure oil (working oil) returned to the working oil tank.

  Next, the exhaust gas processing device 18 that purifies the exhaust gas discharged from the engine 10 will be described.

  In other words, reference numeral 18 denotes an exhaust gas processing device provided on the exhaust side of the engine 10. As shown in FIG. 2, the exhaust gas processing device 18 is disposed on the upper left side of the engine 10, for example, at a position above the hydraulic pump 15, and the exhaust pipe 12 of the engine 10 is connected to the upstream side thereof. . The exhaust gas treatment device 18 constitutes an exhaust gas passage together with the exhaust pipe 12, and removes harmful substances contained in the exhaust gas while the exhaust gas flows from the upstream side to the downstream side.

  Here, the engine 10 made of a diesel engine has high efficiency and excellent durability. However, the exhaust gas of the engine 10 contains harmful substances such as particulate matter (PM), nitrogen oxides (NOx), and carbon monoxide (CO). On the other hand, in recent years, some diesel engines can reduce particulate matter (PM) emissions. Therefore, in the first embodiment, the engine 10 is configured to reduce the amount of particulate matter discharged (that can be operated with a small amount of particulate matter discharged), and the exhaust gas attached to the exhaust pipe 12. The processing device 18 includes an oxidation catalyst (DOC) 20 that oxidizes and removes components in the exhaust gas. That is, as shown in FIG. 3, the exhaust gas treatment device 18 is provided with a cylindrical casing 19, an oxidation catalyst 20 detachably accommodated in the casing 19, and downstream of the oxidation catalyst 20. And a discharge port 21. The exhaust gas treatment device 18 of the first embodiment is not provided with a particulate matter removal filter (DPF) that collects particulate matter in the exhaust gas.

The oxidation catalyst 20 is made of a ceramic cylindrical tube having an outer diameter dimension equivalent to the inner diameter dimension of the casing 19, for example. A large number of through holes (not shown) are formed in the oxidation catalyst 20 in the axial direction, and the inner surface thereof is coated with a noble metal. The oxidation catalyst 20 oxidizes and removes carbon monoxide (CO), hydrocarbon (HC), etc. contained in the exhaust gas by circulating the exhaust gas through each through hole under a predetermined temperature condition. Then, nitrogen oxide (NO) is removed as nitrogen dioxide (NO ₂ ).

  The discharge port 21 is located downstream of the oxidation catalyst 20 and connected to the outlet side of the casing 19. The exhaust port 21 includes a chimney and a silencer that release exhaust gas after being purified into the atmosphere, for example.

  Next, the sensors 22, 23, 24, the alarm 25, and the controller 26 for controlling the engine 10, monitoring the exhaust gas processing device 18, and notifying an operator (driver) as necessary will be described.

  Reference numeral 22 denotes a rotational speed (rotational speed) N of the engine 10, and the rotational sensor 22 detects the rotational speed N of the engine 10 and outputs a detection signal to a controller 26 described later. Based on the engine speed N detected by the rotation sensor 22, the controller 26 performs, for example, speed control for maintaining the speed of the engine 10 at a predetermined speed.

  Reference numerals 23 and 24 denote pressure sensors provided in the casing 19 of the exhaust gas treatment device 18. As shown in FIG. 3, the pressure sensors 23 and 24 are arranged on the inlet side (upstream side) and the outlet side (downstream side) of the oxidation catalyst 20 so as to be separated from each other, and the respective detection signals are sent to the controller 26 described later. Output. That is, the pressure sensor 23 serves as an inlet side pressure detecting means for detecting the pressure P1 on the inlet side (upstream side of the oxidation catalyst 20) of the oxidation catalyst 20, and the pressure sensor 24 is provided on the outlet side (oxidation catalyst 20) of the oxidation catalyst 20. It becomes an outlet side pressure detecting means for detecting the pressure P2 on the downstream side. As will be described later, the controller 26 calculates a differential pressure ΔP from the pressure P1 on the inlet side detected by the pressure sensor 23 and the pressure P2 on the outlet side detected by the pressure sensor 24, and based on the differential pressure ΔP, Determination of the closed state of the oxidation catalyst 20 is performed. In this case, the differential pressure ΔP of the oxidation catalyst 20 is calculated by the following equation 1 when the pressure on the inlet side detected by the pressure sensor 23 is P1 and the pressure on the outlet side detected by the pressure sensor 24 is P2. .

  The alarm 25 is provided in the vicinity of the driver's seat in the cab 8. The notification device 25 is connected to a controller 26 described later and, based on a command (notification signal) from the controller 26, notifies the operator, for example, that the oxidation catalyst 20 is in a closed state, the rotational speed of the engine 10 and the output. This means that fail-safe control is performed, and that maintenance such as inspection, repair, and replacement is necessary. Here, the notification device 25 can be configured by a buzzer that emits a notification sound, a speaker that emits sound, a light or a monitor that displays notification contents, and the like. When the controller 26 determines that the oxidation catalyst 20 is in a closed state by the controller 26, the notification device 25 issues a notification sound and a notification display to the operator based on a command (notification signal) from the controller 26. Notify that.

  Reference numeral 26 denotes a controller (control device, control unit) composed of a microcomputer or the like. The controller 26 is connected at its input side to the fuel injection device 14, the rotation sensor 22, the pressure sensors 23, 24, and the like. The output side of the controller 26 is connected to the fuel injection device 14, the alarm 25, and the like. The controller 26 has a storage unit 26A composed of ROM, RAM, etc., and in this storage unit 26A, a processing program shown in FIG. 4 to be described later, that is, determination of the blocking state of the oxidation catalyst 20 and fail safe control processing. A program, a preset differential pressure threshold value Pt, and the like are stored.

  Here, based on the pressure P1 on the inlet side of the oxidation catalyst 20 and the pressure P2 on the outlet side of the oxidation catalyst 20 detected by the pressure sensors 23, 24, the controller 26 is blocked due to adhesion of soot components (soot) by the oxidation catalyst 20. It is determined that the oxidation catalyst 20 is in the blocked state by the oxidation catalyst blockage determining means (processing in step 3 of FIG. 4 described later) for determining whether or not the state (abnormally blocked state) is present. Fail-safe control means (processing in step 5 of FIG. 4 described later) is provided.

  That is, the controller 26 calculates the differential pressure ΔP between the inlet side and the outlet side of the oxidation catalyst 20 based on the above-described equation (1) (step 2 in FIG. 4 described later), and this differential pressure ΔP is set in advance. It is determined whether or not it is equal to or greater than the differential pressure threshold Pt (the process of step 3 in FIG. 4 described later). In this case, the differential pressure threshold Pt is a determination value for determining whether or not the oxidation catalyst 20 is in the closed state. Therefore, the differential pressure threshold value Pt is based on experiments, calculations, simulations, and the like in advance so that it can be appropriately determined that the oxidation catalyst 20 is in the closed state based on the relationship between the differential pressure ΔP and the state of the oxidation catalyst 20. Set its value.

  When the differential pressure ΔP becomes equal to or greater than the differential pressure threshold value Pt, the controller 26 determines that the oxidation catalyst 20 is in a closed state due to the adhesion of soot components (step 4 in FIG. 4 described later). In this case, the controller 26 notifies the operator that the oxidation catalyst 20 is in a closed state through the alarm device 25 and performs fail-safe control for limiting the rotation speed and output of the engine 10 as necessary ( Step 5 in FIG. 4 described later). In the fail-safe control, for example, when the operation of the engine 10 is continued for a predetermined time set in advance, the engine 10 can be stopped.

  The operator knows that the oxidation catalyst 20 is in the closed state by the notification from the notification device 25 and the operation of the engine 10 being restricted. As a result, the operator can request, for example, maintenance such as inspection, repair, replacement, etc. from a service person who performs maintenance, and can maintain the oxidation catalyst 20 (step 6 in FIG. 4 described later). processing). The process of FIG. 4 executed by the controller 26 will be described later.

  The hydraulic excavator 1 according to the first embodiment has the above-described configuration, and the operation thereof will be described next.

  The operator of the hydraulic excavator 1 gets on the cab 8 of the upper swing body 4, starts the engine 10, and drives the hydraulic pump 15. Thereby, the pressure oil from the hydraulic pump 15 is supplied to various actuators via the control valve. When the operator who has boarded the cab 8 operates the operating lever for traveling, the lower traveling body 2 can be moved forward or backward.

  On the other hand, when the operator in the cab 8 operates the operation lever for work, the work device 5 can be moved up and down to perform excavation work of earth and sand. In this case, since the small excavator 1 has a small turning radius by the upper swing body 4, for example, even in a narrow work site such as an urban area, a side ditching operation or the like can be performed while the upper swing body 4 is driven to rotate.

  When the engine 10 is in operation, hydrocarbons (HC), nitrogen oxides (NO), carbon monoxide (CO), and the like are discharged from the exhaust pipe 12. At this time, the exhaust gas treatment device 18 can oxidize and remove hydrocarbons (HC), nitrogen oxides (NO), carbon monoxide (CO) and the like in the exhaust gas by the oxidation catalyst 20. Thereby, the purified exhaust gas can be discharged to the outside through the discharge port 21.

  By the way, the oxidation catalyst 20 of the exhaust gas treatment device 18 may be in a closed state due to adhesion of soot components (soot) in the exhaust gas. That is, when the fuel that does not vaporize reaches the oxidation catalyst 20, the fuel adheres to the oxidation catalyst 20 and becomes a soot component. More specifically, for example, when fuel is not properly injected by the fuel injection device 14 of the engine 10, unburned fuel adheres to the oxidation catalyst 20, and this unburned fuel is exposed to a high temperature. Turn into. And this soot component adheres to the upper surface (platinum layer) of the oxidation catalyst 20, and when the oxidation catalyst 20 becomes a blockage state, there exists a possibility that the oxidation function of the oxidation catalyst 20 may fall.

  On the other hand, the prior art according to Patent Document 1 is configured to determine the deterioration of the oxidation catalyst constituting the exhaust gas processing device based on the fuel injection amount of the engine. However, in this configuration, for example, when the engine fuel injection device (injector) malfunctions, there is a possibility that the deterioration of the oxidation catalyst cannot be determined.

  On the other hand, in the first embodiment, the controller 26 determines whether the oxidation catalyst 20 is closed based on the differential pressure ΔP that is the difference between the pressure P1 on the inlet side of the oxidation catalyst 20 and the pressure P2 on the outlet side. judge. In addition to this, when the controller 26 determines that the oxidation catalyst 20 is in the closed state, the controller 26 notifies the operator that the oxidation catalyst 20 is in the closed state, and outputs the rotation speed and output of the engine 10 as necessary. Perform limited fail-safe control. Processing performed by the controller 26 will be described with reference to the flowchart of FIG. 4 is repeatedly executed by the controller 26 every predetermined control time (with a predetermined control cycle) while the controller 26 is energized.

  When the accessory is turned ON or the engine 10 is started (ignition is turned ON), the controller 26 is energized. When the processing operation of FIG. 4 is started, in Step 1, the pressures P1 and P2 are read from the pressure sensors 23 and 24, respectively. . That is, the upstream pressure P1 and the downstream pressure P2 of the oxidation catalyst 20 are read. In the next step 2, the differential pressure ΔP between the upstream pressure P1 and the downstream pressure P2 of the oxidation catalyst 20 is calculated by the above-described equation (1).

  In the next step 3, it is determined whether or not the oxidation catalyst 20 is in a closed state. That is, in step 3, it is determined whether or not the differential pressure ΔP calculated in step 2 is equal to or greater than a differential pressure threshold Pt that is a determination value as to whether or not the closed state is present. The differential pressure threshold value Pt is a value based on experiments, calculations, simulations, etc. in advance so that it can be appropriately determined that the oxidation catalyst 20 is in a closed state based on the relationship between the differential pressure ΔP and the state of the oxidation catalyst 20. Can be set. If it is determined “NO” in step 3, that is, if the differential pressure ΔP is less than the differential pressure threshold Pt (ΔP <Pt), the process returns to the start (before), and the processes in and after step 1 are repeated.

  On the other hand, if “YES” is determined in step 3, that is, if it is determined that the differential pressure ΔP is greater than or equal to the differential pressure threshold Pt (ΔP ≧ Pt), the process proceeds to step 4 and it is determined that the oxidation catalyst 20 is in the closed state. . In the following step 5, the operator is notified through the alarm device 25 that the oxidation catalyst 20 is in a closed state, and fail-safe control is performed to limit the rotational speed and output of the engine 10 as necessary. In the fail-safe control, for example, when the operation of the engine 10 is continued for a predetermined time set in advance, the engine 10 can be stopped.

  The operator knows that the oxidation catalyst 20 is in the closed state by the notification from the notification device 25 and the operation of the engine 10 being restricted. Thereby, the operator can request maintenance such as inspection, repair, replacement, etc., for example, to a service person who performs maintenance. If it is determined in step 6 that the oxidation catalyst 20 has been serviced, the process returns to the start via a return, and the processes in and after step 1 are repeated.

  Thus, according to the first embodiment, the controller 26 performs the process of Step 3 and the subsequent Step 4 so that the oxidation catalyst 20 is blocked, that is, is blocked due to the deposition of soot components (soot). It can be determined whether or not there is. In this case, in step 3, the pressures P1, P2 read in step 1, that is, the pressures P1, P1 on the inlet side (upstream side) and outlet side (downstream side) of the oxidation catalyst 20 detected by the pressure sensors 23, 24 are detected. A determination is made based on P2. More specifically, depending on whether or not the differential pressure ΔP (= P1−P2) between the inlet-side pressure P1 and the outlet-side pressure P2 calculated in step 2 is equal to or greater than a preset differential pressure threshold Pt, It is determined whether the oxidation catalyst 20 is in a closed state.

  For this reason, for example, even when a malfunction occurs in the injector of the fuel injection device 14, the determination of the closed state of the oxidation catalyst 20 by the process of step 3 can be performed stably. In addition, since the determination of the closed state of the oxidation catalyst 20 can be performed by the process of step 3, it can be performed as a simple process without requiring a complicated determination process.

  In addition, if it is determined in step 3 and the processing in step 4 that follows that that the oxidation catalyst 20 is in a closed state, in step 5, the fact is notified to the operator through the alarm 25 and the operation of the engine 10 ( Fail-safe control for limiting the rotation speed and output) is performed. As a result, when the oxidation catalyst 20 is in the closed state, the operator (or service person) can perform necessary maintenance such as inspection, repair, and replacement of the oxidation catalyst. Further, even when maintenance is not performed, the operation of the engine 10 is restricted, so that the engine 10 can be protected and the exhaust gas that is not sufficiently oxidized can be prevented from being discharged.

  In the first embodiment, a specific example of the oxidation catalyst blockage determination means in which the process in step 3 of FIG. 4 is a constituent element of the present invention is shown, and the process in step 5 of FIG. 4 is a constituent element of the present invention. The example of a certain fail safe control means is shown.

  Next, FIG. 5 and FIG. 6 show a second embodiment of the present invention. The feature of the second embodiment is that the oxidation catalyst inlet side (upstream side) and outlet side (upstream side) and outlet side (upstream side) and outlet side (downstream side) pressure (P1, P2) The configuration is such that the determination of the closed state of the oxidation catalyst is also performed using the temperature (T1, T2) on the downstream side. In the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  In the figure, reference numerals 31 and 32 denote temperature sensors provided in the casing 19 of the exhaust gas treatment device 18. As shown in FIG. 5, the temperature sensors 31 and 32 are arranged on the inlet side (upstream side) and the outlet side (downstream side) of the oxidation catalyst 20 so as to be separated from each other, and each detection signal is sent to the controller 33 described later. Output. That is, the temperature sensor 31 serves as an inlet side temperature detecting means for detecting the temperature T1 on the inlet side (upstream side of the oxidation catalyst 20) of the oxidation catalyst 20, and the temperature sensor 32 is provided on the outlet side (oxidation catalyst 20) of the oxidation catalyst 20. It is an outlet side temperature detecting means for detecting the temperature T2 on the downstream side. As will be described later, the controller 33 calculates a temperature difference ΔT based on the temperature T1 on the inlet side detected by the temperature sensor 31 and the temperature T2 on the outlet side detected by the temperature sensor 32, and based on the temperature difference ΔT, The oxidation active state of the oxidation catalyst 20 is determined. In this case, the temperature difference ΔT of the oxidation catalyst 20 is calculated by the following equation (2) when the temperature on the inlet side detected by the temperature sensor 31 is T1 and the temperature on the outlet side detected by the temperature sensor 32 is T2. .

  Reference numeral 33 denotes a controller (control device, control unit) composed of a microcomputer or the like. The controller 33 has an input side connected to the fuel injection device 14, the rotation sensor 22, the pressure sensors 23 and 24, the temperature sensors 31, 32, and the like. Yes. The output side of the controller 33 is connected to the fuel injection device 14, the alarm 25, and the like. The controller 33 is the same as the controller 26 of the first embodiment, and has a storage unit 33A composed of ROM, RAM, and the like. In the storage unit 33A, a processing program shown in FIG. 6 to be described later, that is, a determination program of the blocking state of the oxidation catalyst 20, a determination of the oxidation active state of the oxidation catalyst 20, and a fail-safe control processing program, a preset differential pressure A threshold value Pt, a temperature difference threshold value Tt, and the like are stored.

  Here, similarly to the controller 26 of the first embodiment, the controller 33 is based on the pressure P1 on the inlet side and the pressure P2 on the outlet side of the oxidation catalyst 20 detected by the pressure sensors 23 and 24. 20 is provided with an oxidation catalyst blockage determining means (the process of step 13 in FIG. 6) for determining whether or not 20 is in a blockage state (abnormal blockage state) due to adhesion of soot components (soot). In addition to this, in the second embodiment, the controller 33 oxidizes the oxidation catalyst 20 based on the temperature T1 on the inlet side and the temperature T2 on the outlet side of the oxidation catalyst 20 detected by the temperature sensors 31 and 32. The active state is also determined (oxidation activity determining means, step 16 in FIG. 6). Furthermore, the controller 33 determines that the oxidation catalyst 20 is in the closed state (more specifically, if it is determined that the oxidation catalyst 20 is in the closed state and the oxidation active state has decreased). Further, a fail safe control means for performing the fail safe control (the process of step 18 in FIG. 6) is provided.

  That is, the controller 33 calculates the differential pressure ΔP between the inlet side and the outlet side of the oxidation catalyst 20 based on the above-mentioned equation (1) (processing in step 12 in FIG. 6), and the differential pressure ΔP is set in advance. It is determined whether or not it is equal to or higher than the pressure threshold value Pt (processing of step 13 in FIG. 6). In addition to this, the controller 33 calculates the temperature difference ΔT between the inlet side and the outlet side of the oxidation catalyst 20 based on the above-described equation (2) (processing in step 15 in FIG. 6). It is determined whether or not the temperature difference threshold value Tt is equal to or less than the set temperature difference threshold value Tt (processing of step 16 in FIG. 6). In this case, the temperature difference threshold value Tt is a determination value for determining whether or not the oxidation activation state of the oxidation catalyst 20 has been reduced (oxidation activation has been reduced). Therefore, the temperature difference threshold value Tt is experimentally calculated in advance so that it can be appropriately determined that the oxidation activity state of the oxidation catalyst 20 has decreased based on the relationship between the temperature difference ΔT and the oxidation activity state of the oxidation catalyst 20. The value is set based on simulation or the like.

  When the pressure difference ΔP is equal to or greater than the pressure difference threshold value Pt and the temperature difference ΔT is equal to or less than the temperature difference threshold value Tt, the controller 33 is in a closed state due to the adhesion of soot components by the oxidation catalyst 20 (more specifically, Determines that the oxidation catalyst 20 is in a closed state and the oxidation active state has decreased) (the process of step 17 in FIG. 6). In this case, the controller 33 notifies the operator that the oxidation catalyst 20 is in a closed state (and the oxidation active state has been lowered) through the notification device 25 and, if necessary, the engine 10. Fail-safe control is performed to limit the number of rotations and output (processing of step 18 in FIG. 6). In the fail-safe control, for example, when the operation of the engine 10 is continued for a predetermined time set in advance, the engine 10 can be stopped.

  The operator knows that the oxidation catalyst 20 is in the closed state (and the oxidation active state is lowered) by the notification from the notification device 25 and the operation of the engine 10 being restricted. As a result, the operator can request, for example, maintenance such as inspection, repair, replacement, etc. from a service person who performs maintenance, and can perform maintenance of the oxidation catalyst 20 (processing of step 19 in FIG. 6). .

  Next, processing performed by the controller 33 will be described with reference to the flowchart of FIG. 6 is also repeatedly executed by the controller 33 every predetermined control time (with a predetermined control cycle) while the controller 33 is energized, similarly to the process of FIG. 4 of the first embodiment. Is done.

  When the accessory is turned on or the engine 10 is started (ignition is turned on), energization of the controller 33 is started, and when the processing operation of FIG. 6 is started, the processing of step 11 to step 13 is performed. The processing from step 11 to step 13 is the same as the processing from step 1 to step 3 in FIG. 4 of the first embodiment.

  If “YES” in step 13, that is, if it is determined that the differential pressure ΔP is equal to or greater than the differential pressure threshold Pt (ΔP ≧ Pt), the process proceeds to step 14 where the temperatures T1 and T2 are read from the temperature sensors 31 and 32, respectively. Include. That is, the upstream temperature T1 and the downstream temperature T2 of the oxidation catalyst 20 are read. In the next step 15, the temperature difference ΔT between the upstream temperature T1 and the downstream temperature T2 of the oxidation catalyst 20 is calculated by the above-described equation (2).

  In the next step 16, it is determined whether or not the oxidation active state of the oxidation catalyst 20, more specifically, the oxidation active state of the oxidation catalyst 20 has decreased. That is, in step 16, it is determined whether or not the temperature difference ΔT calculated in step 15 is equal to or less than a temperature difference threshold value Tt that is a determination value as to whether or not the oxidation active state of the oxidation catalyst 20 has decreased. Based on the relationship between the temperature difference ΔT and the oxidation activity state of the oxidation catalyst 20, the temperature difference threshold value Tt is previously tested, calculated, simulated, etc. so that it can be appropriately determined that the oxidation activity state of the oxidation catalyst 20 has decreased. The value can be set based on. If “NO” in step 16, that is, if it is determined that the temperature difference ΔT exceeds the temperature difference threshold value Tt (ΔT> Tt), the process returns to the start (before) and the processes in and after step 11 are repeated.

  On the other hand, if “YES” in step 16, that is, if it is determined that the temperature difference ΔT is equal to or less than the temperature difference threshold value Tt (ΔT ≦ Tt), the process proceeds to step 17 where the oxidation catalyst 20 is in a closed state. Specifically, it is determined that the oxidation catalyst 20 is in a closed state and the oxidation active state is lowered. In the subsequent step 18, the operator is notified through the alarm device 25 that the oxidation catalyst 20 is in a closed state (and the oxidation active state has been lowered), and the rotational speed of the engine 10 as necessary. And fail-safe control to limit output. In the fail-safe control, for example, when the operation of the engine 10 is continued for a predetermined time set in advance, the engine 10 can be stopped.

  The operator knows that the oxidation catalyst 20 is in the closed state (and the oxidation active state is lowered) by the notification from the notification device 25 and the operation of the engine 10 being restricted. Thereby, the operator can request maintenance such as inspection, repair, replacement, etc., for example, to a service person who performs maintenance. If it is determined in step 19 that the oxidation catalyst 20 has been serviced, the process returns to the start via a return, and the processes in and after step 11 are repeated.

  In the second embodiment, the processing of the controller 33 as described above performs the determination of the blocked state in consideration of the oxidation active state of the oxidation catalyst 20 and necessary fail-safe control. There is no particular difference from that according to the first embodiment.

  In particular, in the case of the second embodiment, the controller 33 includes the pressures P1 and P2 on the inlet side (upstream side) and the outlet side (downstream side) of the oxidation catalyst 20, and the inlet side (upstream side) of the oxidation catalyst 20. And the closed state of the oxidation catalyst 20 are determined based on the temperatures T1 and T2 on the outlet side (downstream side). That is, the controller 33 adds the pressures P1 and P2 on the inlet side (upstream side) and the outlet side (downstream side) of the oxidation catalyst 20, and on the inlet side (upstream side) and outlet side (downstream side) of the oxidation catalyst 20. The closed state of the oxidation catalyst 20 is determined using the temperatures T1 and T2.

  In this case, the oxidation activity of the oxidation catalyst 20 depends on whether or not the temperature difference ΔT (= T2−T1), which is the difference between the inlet side temperature T1 and the outlet side temperature T2, is equal to or less than a preset temperature difference threshold value Tt. It is determined whether or not the state is lowered. Therefore, the determination of the closed state of the oxidation catalyst 20 can be performed in consideration of the oxidation active state of the oxidation catalyst 20, and the closed state of the oxidation catalyst 20 can be determined more finely (with high accuracy). For example, when the oxidation catalyst 20 is in a closed state and the oxidation active state is lowered, it can be determined that the oxidation catalyst 20 is in a failure state.

  In the second embodiment, a specific example of the oxidation catalyst blockage determination means in which the processing in steps 13 and 16 in FIG. 6 is a constituent element of the present invention is shown, and the processing in step 18 in FIG. The specific example of the fail safe control means which is a requirement is shown.

  Next, FIG. 7 and FIG. 8 show a third embodiment of the present invention. The feature of the third embodiment resides in that the exhaust gas treatment device includes a filter that collects particulate matter in the exhaust gas discharged from the engine in addition to the oxidation catalyst. Note that in the third embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  In the figure, 41 is an exhaust gas processing device for purifying exhaust gas discharged from the engine 10, and the exhaust gas processing device 41 oxidizes and removes carbon monoxide (CO) and the like in the exhaust gas. And a particulate matter removal filter (DPF) 43 that collects and removes particulate matter (PM) in the exhaust gas.

  That is, the exhaust gas processing device 41 has a cylindrical casing 42 configured by, for example, detachably connecting a plurality of cylinders in front and back. In the casing 42, in addition to the oxidation catalyst 20 similar to that of the first embodiment described above, a particulate matter removing filter 43 (hereinafter referred to as filter 43) as a filter is detachably accommodated.

  The filter 43 is disposed in the casing 42 on the downstream side of the oxidation catalyst 20. The filter 43 collects particulate matter in the exhaust gas discharged from the engine 10 and purifies the exhaust gas by burning and removing the collected particulate matter. For this purpose, the filter 43 is constituted by a cellular cylindrical body in which a large number of small holes (not shown) are provided in the axial direction on a porous member made of, for example, a ceramic material. Thus, the filter 43 collects the particulate matter through a large number of small holes, and the collected particulate matter is burned and removed by a regeneration process of the regeneration device 44 described later. As a result, the filter 43 is regenerated.

  Next, the regeneration device 44 that performs regeneration of the filter 43 will be described.

  That is, reference numeral 44 denotes a regenerator that regenerates the filter 43 by burning particulate matter collected by the filter 43 of the exhaust gas treatment device 41. The regeneration device 44 includes a fuel injection device 14, a rotation sensor 22, pressure sensors 23, 24, 45, temperature sensors 46, 47, and a controller 48. For example, the regeneration device 44 performs fuel injection for regeneration processing (additional injection after the combustion process) called post-injection by the fuel injection device 14 in accordance with a command signal (control signal) of a controller 48 described later. Thereby, the temperature of the exhaust gas in the exhaust pipe 12 is raised, and the particulate matter deposited on the filter 43 is burned and removed.

  In this case, the controller 48 collects in the filter 43 based on, for example, the engine speed N detected by the rotation sensor 22, the fuel injection amount F injected by the fuel injection device 14, and other necessary state quantities. The amount of collected particulate matter can be estimated. Then, the controller 48 determines whether or not to perform regeneration based on the first estimated collection amount (and the second estimated collection amount described later) that is the estimated collection amount, and so on. Accordingly, for example, regeneration by post injection can be performed.

  The pressure sensor 45 is provided in the casing 42 of the exhaust gas processing device 41. As shown in FIG. 7, the pressure sensor 45 serves as a filter outlet side pressure detecting means for detecting the pressure P3 on the outlet side (downstream side) of the filter 43. For this purpose, the pressure sensor 45 is arranged on the outlet side (downstream side of the filter 43) of the filter 43 and outputs a detection signal to the controller 48.

  For example, the controller 48 detects the pressure P2 on the outlet side of the oxidation catalyst 20 detected by the pressure sensor 24, that is, the pressure P2 on the inlet side (upstream side) of the filter 43 and the pressure P2 on the outlet side of the filter 43 detected by the pressure sensor 45. Based on the pressure P3 and other necessary state quantities, the amount of particulate matter collected by the filter 43 can be estimated. Then, the controller 48 determines whether or not to perform regeneration based on the second estimated collection amount (and the above-described first estimated collection amount) that is the estimated collection amount, and is necessary. Accordingly, for example, regeneration by post injection can be performed.

Further, as will be described later, the controller 48 calculates the following equation (3) from the pressure P1 on the inlet side of the oxidation catalyst 20 detected by the pressure sensor 23 and the pressure P3 on the outlet side of the filter 43 detected by the pressure sensor 45. Based on this, the differential pressure ΔP ₁ is calculated.

At the same time, the controller 48 calculates the following number from the pressure P2 on the outlet side (the inlet side of the filter 43) of the oxidation catalyst 20 detected by the pressure sensor 24 and the pressure P3 on the outlet side of the filter 43 detected by the pressure sensor 45. A differential pressure ΔP ₂ is calculated based on the four equations.

As will be described later, the controller 48 can determine the closed state of the oxidation catalyst 20 based on the differential pressure ΔP ₁ and the differential pressure ΔP ₂ .

  The temperature sensors 46 and 47 are provided in the casing 42 of the exhaust gas processing device 41. As shown in FIG. 7, the temperature sensors 46 and 47 are arranged on the inlet side (upstream side) and the outlet side (downstream side) of the oxidation catalyst 20 so as to be separated from each other, and output respective detection signals to the controller 48. . That is, the temperature sensor 46 serves as an inlet side temperature detecting means for detecting the temperature T1 on the inlet side (upstream side of the oxidation catalyst 20) of the oxidation catalyst 20, and the temperature sensor 47 is provided on the outlet side (oxidation catalyst 20) of the oxidation catalyst 20. It is an outlet side temperature detecting means for detecting the temperature T2 on the downstream side. The controller 48 calculates a temperature difference ΔT from the inlet side temperature T1 detected by the temperature sensor 46 and the outlet side temperature T2 detected by the temperature sensor 47, and based on this temperature difference ΔT, oxidation of the oxidation catalyst 20 is performed. The active state can be determined. This point is the same as in the second embodiment. In the third embodiment, the description will be made assuming that the determination of the oxidation active state of the oxidation catalyst 20 using the temperature sensors 46 and 47 is not performed. However, as in the second embodiment, the oxidation catalyst 20 It may be configured to determine the oxidation active state.

  Reference numeral 48 denotes a controller (control device, control unit) composed of a microcomputer or the like. The controller 48 has an input side connected to the fuel injection device 14, the rotation sensor 22, the pressure sensors 23, 24, 45, the temperature sensors 46, 47, and the like. Has been. The output side of the controller 48 is connected to the fuel injection device 14, the alarm 25, and the like. The controller 48 includes a storage unit 48A composed of a ROM, a RAM, and the like. In this storage unit 48A, in addition to the processing program for the regeneration processing of the filter 43, the processing program shown in FIG. A processing program for determining the closed state and fail-safe control, preset differential pressure thresholds Pt1, Pt2, and the like are stored.

  Here, the controller 48 determines whether the oxidation catalyst 20 is based on the pressure P 1 on the inlet side of the oxidation catalyst 20 detected by the pressure sensors 23, 24, 45, the pressure P 2 on the outlet side, and the pressure P 3 on the outlet side of the filter 43. Oxidation catalyst blockage determining means (processing in steps 23 and 26 in FIG. 8) for determining whether or not the blockage state (abnormally blocked state) is caused by adhesion of soot component (soot), and the oxidation catalyst blockage determination means Fail-safe control means for performing fail-safe control when it is determined that the oxidation catalyst 20 is in the closed state (processing of step 28 in FIG. 8) is provided.

That is, the controller 48 calculates a differential pressure ΔP ₁ between the inlet side of the oxidation catalyst 20 and the outlet side of the filter 43 based on the above-described equation (3) (processing in step 22 in FIG. 8), and this differential pressure ΔP. It is determined whether ₁ is equal to or greater than a preset differential pressure threshold value Pt1 (step 23 in FIG. 8). In this case, the differential pressure threshold Pt1 is one determination value for determining whether or not the oxidation catalyst 20 is in the closed state. More specifically, this is a determination value for the closed state of the oxidation catalyst 20 including the collection state (deposition state) of the filter 43 that is in the closed state of the exhaust gas treatment device 18 as a whole. Therefore, differential pressure threshold value Pt1, based on the relationship between the differential pressure [Delta] P ₁ and the state of the oxidation catalyst 20 and the filter 43, to properly determine that the oxidation catalyst 20 is in a closed state, an experiment in advance, calculation, The value is set based on simulation or the like.

Here, when the differential pressure [Delta] P ₁ becomes higher differential pressure threshold value Pt1, the oxidation catalyst 20 is considered likely to be in the closed state. Therefore, when the differential pressure ΔP ₁ is equal to or greater than the differential pressure threshold value Pt ₁ , the controller 48 determines that the outlet side of the oxidation catalyst 20 (= the inlet side of the filter 43) and the outlet side of the filter 43 based on the above equation (4). The pressure difference ΔP ₂ is calculated (step 25 in FIG. 8), and it is determined whether or not the pressure difference ΔP ₂ is less than or equal to a preset pressure difference threshold value Pt ₂ (step 26 in FIG. 8). . In this case, the differential pressure threshold value Pt2 is another determination value for determining whether or not the oxidation catalyst 20 is in the closed state. More specifically, it is a determination value for the collection state (deposition state) of the filter 43. Therefore, differential pressure threshold value Pt2 is to properly determine that the differential pressure [Delta] P ₂ and the oxidation catalyst 20 from the relationship between the state and the differential pressure [Delta] P ₁ of the filter 43 is closed, pre-experiment, calculation, simulation or the like Set its value based on.

Here, when the differential pressure ΔP ₁ is equal to or higher than the differential pressure threshold Pt ₁ and the differential pressure ΔP ₂ is equal to or lower than the differential pressure threshold Pt ₂ , the trapped amount (deposition amount) of the filter 43 is small and the differential pressure of the filter 43 is reduced. Although ΔP ₂ is small, the differential pressure ΔP _{1 of} the exhaust gas treatment device 18 as a whole is in a high state, so it is considered that the oxidation catalyst 20 is in a closed state. Therefore, when the differential pressure ΔP ₁ is equal to or higher than the differential pressure threshold Pt ₁ and the differential pressure ΔP ₂ is equal to or lower than the differential pressure threshold Pt ₂ , the controller 48 enters the closed state due to the adhesion of the soot component by the oxidation catalyst 20. It is determined that it exists (the process of step 27 in FIG. 8). In this case, the controller 48 notifies the operator that the oxidation catalyst 20 is in a closed state through the alarm device 25 and performs fail-safe control for limiting the rotation speed and output of the engine 10 as necessary ( Step 28 in FIG. 8). In the fail-safe control, for example, when the operation of the engine 10 is continued for a predetermined time set in advance, the engine 10 can be stopped.

  The operator knows that the oxidation catalyst 20 is in the closed state by the notification from the notification device 25 and the operation of the engine 10 being restricted. As a result, the operator can request, for example, maintenance such as inspection, repair, replacement, etc., from a service person who performs maintenance, and can maintain the oxidation catalyst 20 (processing of step 29 in FIG. 8). .

  In the third embodiment, when particulate matter, which is a harmful substance, is discharged as the engine 10 is operated, the exhaust gas processing device 41 causes hydrocarbons (HC) in the exhaust gas, Nitrogen oxide (NO) and carbon monoxide (CO) are removed by oxidation, and the filter 43 collects particulate matter contained in the exhaust gas. Thereby, the purified exhaust gas can be discharged to the outside through the downstream outlet 21. Further, the collected particulate matter is burned and removed (regenerated) by the regenerator 44. For example, the oxidation reaction via the oxidation catalyst 20 and the load applied to the engine 10 increase, so that the temperature of the exhaust gas rises, and thereby the particulate matter deposited on the filter 43 can be combusted (low temperature). Regeneration). Further, by performing fuel injection for regeneration called post-injection with the fuel injection device 14, the temperature of the exhaust gas can be raised and the particulate matter deposited on the filter 43 can be forcibly burned (high temperature regeneration). .

  On the other hand, the oxidation catalyst 20 of the exhaust gas treatment device 18 may become blocked due to the adhesion of soot components (soot) in the exhaust gas. That is, when the fuel that does not vaporize reaches the oxidation catalyst 20, the fuel adheres to the oxidation catalyst 20 and becomes a soot component. More specifically, for example, when fuel is not properly injected by the fuel injection device 14 of the engine 10, unburned fuel adheres to the oxidation catalyst 20, and this unburned fuel is exposed to a high temperature. Turn into.

Then, the soot component adheres to the upper surface (platinum layer) of the oxidation catalyst 20 and the oxidation catalyst 20 is in a closed state. For example, the oxidation function such as the function of oxidizing NO into NO ₂ may be reduced. . As a result, the temperature difference of the oxidation catalyst 20 becomes small (the exhaust gas temperature increase amount at the oxidation catalyst 20 decreases), and there is a possibility that sufficient regeneration is not performed by the filter 43 located on the downstream side. In this case, for example, particulate matter (PM) may be excessively deposited on the filter 43.

  On the other hand, in the third embodiment, the controller 48 determines whether or not the oxidation catalyst 20 is closed, and if it is determined that the oxidation catalyst 20 is in the closed state, the oxidation catalyst 20 is sent to the operator. Fail-safe control for notifying that the engine is in the closed state and limiting the rotational speed and output of the engine 10 as necessary is performed. Processing performed by the controller 48 will be described with reference to the flowchart of FIG. 8 is repeatedly executed by the controller 48 every predetermined control time (with a predetermined control cycle) while the controller 48 is energized.

When the accessory is turned on or the engine 10 is started (ignition is turned on), the controller 48 is energized. When the processing operation of FIG. 8 is started, the pressures P1 and P3 are read from the pressure sensors 23 and 45 in step 21, respectively. . That is, the pressure P1 upstream of the oxidation catalyst 20 and the pressure P3 downstream of the filter 43 are read. In the next step 22, the differential pressure ΔP ₁ between the pressure P ₁ on the upstream side of the oxidation catalyst 20 and the pressure P 3 on the downstream side of the filter 43 is calculated by the above-described equation (3).

In the next step 23, the previous stage (previous stage) is determined as to whether or not the oxidation catalyst 20 is in the closed state. That is, in step 23, the differential pressure ΔP ₁ calculated in step 22, that is, the closed state of the exhaust gas treatment device 18 as a whole (the closed state of the oxidation catalyst 20 including the collection state (deposition state) of the filter 43). corresponding differential pressure [Delta] P ₁ is, it is determined whether the differential pressure threshold value Pt1 above. Differential pressure threshold value Pt1, based on the relationship between the differential pressure [Delta] P ₁ and the state of the oxidation catalyst 20 and the filter 43, to properly determine that the oxidation catalyst 20 is in a closed state, an experiment in advance, calculation, simulation or the like The value can be set based on. If “NO” in step 23, that is, if it is determined that the differential pressure ΔP ₁ is less than the differential pressure threshold Pt ₁ (ΔP ₁ <Pt ₁ ), the process returns to the start (before), and the processing from step 21 is repeated.

On the other hand, if “YES” in step 23, that is, if it is determined that the differential pressure ΔP ₁ is equal to or greater than the differential pressure threshold Pt ₁ (ΔP ₁ ≧ Pt ₁ ), the process proceeds to step 24. In step 24, pressures P2 and P3 are read from the pressure sensors 24 and 45, respectively. That is, the pressure P2 on the downstream side of the oxidation catalyst 20 (= the upstream side of the filter 43) and the pressure P3 on the downstream side of the filter 43 are read. In the next step 25, the differential pressure ΔP ₂ between the pressure P ₂ on the downstream side of the oxidation catalyst 20 (= upstream side of the filter 43) and the pressure P 3 on the downstream side of the filter 43 is calculated by the above-described equation (4).

In the next step 26, a subsequent (final) determination is made as to whether or not the oxidation catalyst 20 is in a closed state. That is, in step 26, it is determined whether or not the differential pressure ΔP ₂ calculated in step 25, that is, the differential pressure ΔP ₂ corresponding to the collection state (deposition state) of the filter 43 is equal to or less than the differential pressure threshold value Pt2. . Differential pressure threshold value Pt2 is to properly determine that the differential pressure [Delta] P ₂ and state and the differential pressure [Delta] P ₁ and the oxidation catalyst 20 from the relationship between the filter 43 is in the closed state, based on pre-experiment, calculation, simulation or the like Can set the value. If “NO” in step 26, that is, if it is determined that the differential pressure ΔP ₂ exceeds the differential pressure threshold value Pt ₂ (ΔP ₂ > Pt ₂ ), the process returns to the start (before) and repeats the processing after step 21. .

On the other hand, if “YES” in step 26, that is, if it is determined that the differential pressure ΔP ₂ is equal to or less than the differential pressure threshold Pt ₂ (ΔP ₂ ≦ Pt ₂ ), the process proceeds to step 27, and the oxidation catalyst 20 is in the closed state. judge. That is, although the collection amount (deposition amount) of the filter 43 is small and the differential pressure ΔP _{2 of the} filter 43 is small, the differential pressure ΔP _{1 of} the exhaust gas treatment device 18 as a whole is high, so the oxidation catalyst 20 is blocked. It is determined that In the subsequent step 28, the operator is informed through the alarm device 25 that the oxidation catalyst 20 is in a closed state, and performs fail-safe control for limiting the rotational speed and output of the engine 10 as necessary. In the fail-safe control, for example, when the operation of the engine 10 is continued for a predetermined time set in advance, the engine 10 can be stopped.

  The operator knows that the oxidation catalyst 20 is in the closed state by the notification from the notification device 25 and the operation of the engine 10 being restricted. Thereby, the operator can request maintenance such as inspection, repair, replacement, etc., for example, to a service person who performs maintenance. If it is determined in step 29 that the oxidation catalyst 20 has been serviced, the process returns to the start via a return, and the processes in and after step 21 are repeated.

  In the third embodiment, the controller 48 determines the closed state of the oxidation catalyst 20 and performs necessary fail-safe control by the processing of the controller 48 as described above. The basic operation of the third embodiment is as described in the first embodiment. There is no particular difference from the form.

  In particular, in the case of the third embodiment, the controller 48 is in the closed state due to the attachment of the soot component (soot) by the processing of Step 23 and Step 26, that is, whether the soot component (soot) is attached. Can be determined. In this case, the controller 48 includes the pressure P1 on the inlet side (upstream side) of the oxidation catalyst 20, the pressure P2 on the inlet side (upstream side) of the filter 43 on the outlet side (downstream side) of the oxidation catalyst 20, and the Based on the pressure P3 on the outlet side (downstream side), the closed state of the oxidation catalyst 20 is determined. For this reason, in the exhaust gas processing device 18 configured to include the filter 43 and the oxidation catalyst 20, it is possible to stably determine the closed state of the oxidation catalyst 20.

  In addition, in the case of the third embodiment, not only the pressure P1 on the inlet side (upstream side) and the pressure P2 on the outlet side (downstream side) of the oxidation catalyst 20 but also the outlet side of the filter 43 ( The pressure P3 on the downstream side is also used, in other words, the blocking state of the oxidation catalyst 20 is determined using a total of three pressures P1, P2, and P3. For this reason, the accuracy (accuracy) of the determination of the closed state of the oxidation catalyst 20 can be improved.

  In the third embodiment, a specific example of the oxidation catalyst blockage determination means in which the processing of steps 23 and 26 in FIG. 8 is a constituent of the present invention is shown, and the processing in step 28 of FIG. 8 is the configuration of the present invention. The specific example of the fail safe control means which is a requirement is shown.

  In the third embodiment described above, based on the pressure P1 on the inlet side of the oxidation catalyst 20, the pressure P2 on the outlet side of the oxidation catalyst 20 (the inlet side of the filter 43), and the pressure P3 on the outlet side of the filter 43. In the above description, the case in which the determination of the closed state of the oxidation catalyst 20 is performed is taken as an example. However, the present invention is not limited to this. For example, based on two pressures P1 and P2 of the pressure P1 on the inlet side of the oxidation catalyst 20 and the pressure P2 on the outlet side (the inlet side of the filter 43), It is good also as a structure which determines the obstruction | occlusion state of the oxidation catalyst 20 like 1 embodiment. Further, for example, pressures P1 and P2 on the inlet side and outlet side of the oxidation catalyst 20 (pressure P3 on the outlet side of the filter 43 as necessary), and the inlet side of the oxidation catalyst 20 detected by the temperature sensors 46 and 47, Based on the temperatures T1 and T2 on the outlet side, as in the second embodiment, the closed state may be determined in consideration of the oxidation active state of the oxidation catalyst 20.

  In each embodiment described above, the case where the exhaust gas processing device 18 is configured by the oxidation catalyst 20 (and the filter 43) has been described as an example. However, the present invention is not limited to this. For example, a urea injection valve, a selective reduction catalyst device, and the like may be used in combination with the oxidation catalyst (and the particulate matter removal filter).

  In each of the above-described embodiments, the case where the exhaust gas processing device 18 is mounted on the small hydraulic excavator 1 has been described as an example. However, the construction machine provided with the exhaust gas treatment device according to the present invention is not limited to this, and may be applied to, for example, a medium-sized or larger hydraulic excavator. Further, the present invention can be widely applied to construction machines such as a hydraulic excavator, a wheel loader, a forklift, and a hydraulic crane having a wheel type lower traveling body.

1 Excavator (construction machine)
6 Rotating frame (frame)
DESCRIPTION OF SYMBOLS 10 Engine 18,41 Exhaust gas processing apparatus 20 Oxidation catalyst 23 Pressure sensor (Inlet side pressure detection means)
24 Pressure sensor (exit side pressure detection means)
26, 33, 48 Controller 31, 46 Temperature sensor (Inlet side temperature detection means)
32, 47 Temperature sensor (outlet side temperature detection means)
43 Particulate matter removal filter (filter)
45 Pressure sensor (filter outlet pressure detection means)

Claims (4)

A frame forming a support structure;
An engine mounted on the frame;
In a construction machine having an oxidation catalyst for oxidizing components in exhaust gas exhausted from the engine, and an exhaust gas treatment device provided on the exhaust side of the engine,
Inlet side pressure detecting means for detecting the pressure (P1) on the inlet side of the oxidation catalyst;
Outlet side pressure detection means for detecting the pressure (P2) on the outlet side of the oxidation catalyst;
An oxidation catalyst that determines whether or not the oxidation catalyst is in a closed state due to adhesion of soot components based on the pressures (P1, P2) detected by the inlet side pressure detection means and the outlet side pressure detection means Occlusion determination means;
A construction machine comprising: a fail-safe control unit that performs fail-safe control when the oxidation catalyst blockage determination unit determines that the oxidation catalyst is blocked. Inlet side temperature detecting means for detecting the temperature (T1) on the inlet side of the oxidation catalyst;
Outlet side temperature detection means for detecting the temperature (T2) on the outlet side of the oxidation catalyst,
The oxidation catalyst blockage determination unit is configured to block the oxidation catalyst based on the temperature (T1, T2) and the pressure (P1, P2) detected by the inlet side temperature detection unit and the outlet side temperature detection unit. The construction machine according to claim 1, which is configured to determine   2. The exhaust gas treatment device according to claim 1, wherein the exhaust gas treatment device has a filter that collects particulate matter in exhaust gas that is located downstream of the oxidation catalyst and is exhausted from the engine, in addition to the oxidation catalyst. The construction machine according to 2. A filter outlet side pressure detecting means for detecting the pressure (P3) on the outlet side of the filter;
The oxidation catalyst blockage determination unit is configured to determine the blockage state of the oxidation catalyst based on the pressure (P3) and the pressures (P1, P2) detected by the filter outlet side pressure detection unit. Item 4. The construction machine according to item 3.

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