JP2011256767A - Exhaust gas purification system of working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform regenerative control of an exhaust emission control device 50 to recover its ability of capturing granular substances using a simple configuration.SOLUTION: The exhaust gas purification system of a working machine is equipped with the exhaust emission control device 50 installed in the exhaust line 77 of an engine 70, hydraulic actuators 160 and 163, a hydraulic pump 101 to supply the working oil to the actuators 160 and 163 using the power of the engine 70, and a regulating valve means 100 installed between the hydraulic pump 101 and a working part hydraulic circuit 103 located downstream thereof. When the clogging condition of the exhaust emission control device 50 becomes at or over the prescribed level, the regulating valve means 100 is actuated to boost the pressure on the pump 101 side, whereby the engine load is increased with the engine speed maintained.

Description

  The present invention relates to an exhaust gas purification system for work machines such as construction machines, agricultural machines, and engine generators.

  In recent years, as high-level exhaust gas regulations related to diesel engines (hereinafter simply referred to as engines) have been applied, air pollutants in exhaust gas have been introduced into construction machines, agricultural machines, and engine generators on which engines are mounted. There has been a demand for mounting an exhaust gas purification device for purification treatment. A diesel particulate filter (hereinafter referred to as DPF) is known as an exhaust gas purification device. The DPF is for collecting particulate matter (hereinafter referred to as PM) in the exhaust gas. In this case, if the PM collected by the DPF exceeds a specified amount, the flow resistance in the DPF increases and the engine output decreases, so the PM accumulated in the DPF is removed by the temperature rise of the exhaust gas, It is often performed to recover the PM collection ability of the DPF (regenerate the DPF).

  For example, in Patent Document 1, an electrothermal heater is provided on the upstream side of the DPF in the exhaust path of the engine, and the PM accumulated in the DPF is burned and removed by heating the exhaust gas led to the DPF by heating the heater. Is disclosed.

JP 2001-280121 A

  However, the configuration of Patent Document 1 requires a heater dedicated to raising the exhaust gas temperature, which increases the number of parts and causes a cost increase. In addition, the heating of the exhaust gas by the heater must be localized, and the exhaust gas cannot be heated uniformly, so that the exhaust gas cannot be purified uniformly, and the temperature of the DPF itself adjacent to the heater is also non-uniform. Thus, there is also a problem that there is a high possibility of damage such as cracking in the DPF.

  Therefore, the present invention has a technical problem to provide an exhaust gas purification system for a working machine that solves these problems.

  According to a first aspect of the present invention, there is provided an exhaust gas purification system for a working machine, an exhaust gas purification device disposed in an exhaust path of an engine, a hydraulic actuator, and a hydraulic pressure for supplying hydraulic oil to the hydraulic actuator by power of the engine. And a regulating valve means disposed between the hydraulic pump and a working part hydraulic circuit downstream thereof, and when the clogged state of the exhaust gas purification device exceeds a specified level, the regulating valve By increasing the pressure on the hydraulic pump side by operating the means, the engine load is increased while maintaining the engine rotation speed.

  According to a second aspect of the present invention, in the exhaust gas purification system for a working machine according to the first aspect, the clogged state of the exhaust gas purification device is below an allowable level lower than the specified level, or the adjusting valve means is When the elapsed time after the operation becomes equal to or longer than a preset set time, the pressure increase on the hydraulic pump side by the adjusting valve means is released.

  According to a third aspect of the present invention, in the exhaust gas purification system for a working machine according to the first or second aspect, the transition time until the adjustment valve means is changed from the non-operating state to the operating state can be changed. It is.

  According to a fourth aspect of the present invention, in the exhaust gas purification system for a working machine according to any one of the first to third aspects, the adjustment valve means is configured to operate by pulse width modulation control. .

  According to the exhaust gas purification system for a work machine according to the first aspect of the present invention, the exhaust gas purification device disposed in the exhaust path of the engine, the hydraulic actuator, and hydraulic oil is supplied to the hydraulic actuator by the power of the engine. And a pressure adjusting valve disposed between the hydraulic pump and a working part hydraulic circuit downstream thereof, and when the clogged state of the exhaust gas purifying device exceeds a specified level, the adjustment is performed. Since the engine load is increased while maintaining the engine rotation speed by increasing the pressure on the hydraulic pump side by the operation of the valve means, for example, the fuel injection control of the engine or the intake / exhaust throttle device, for example Without changing the open / close control setting, the engine output is increased to increase the exhaust gas temperature by increasing the pressure on the hydraulic pump side. It can reproduce the exhaust gas purifying device. That is, the particulate matter collecting ability of the exhaust gas purification device can be recovered.

  According to a second aspect of the present invention, in the exhaust gas purification system for a working machine according to the first aspect, the clogged state of the exhaust gas purification device is below an allowable level lower than the specified level, or the adjusting valve means is When the elapsed time after the operation becomes equal to or longer than a preset time, the pressure increase on the hydraulic pump side by the adjusting valve means is released. When any of the above conditions is satisfied, it can be considered that the clogged state of the exhaust gas purifying device has been improved. Therefore, by releasing the pressure increase on the hydraulic pump side by the adjusting valve means, Regardless of the above, it is possible to prevent the excessive load from being applied to the engine from the hydraulic pump by disabling the regulating valve means. Therefore, the efficiency of the regeneration operation of the exhaust gas purification device can be improved, and the deterioration of fuel consumption associated with the regeneration of the exhaust gas purification device can be suppressed.

  According to the invention of claim 3, in the exhaust gas purification system for a working machine according to claim 1 or 2, the transition time until the adjustment valve means is changed from the non-operating state to the operating state can be changed. For example, the transition time can be set according to the characteristics of the work implement. For this reason, when the exhaust gas purification device is regenerated, there is an effect that a fine measure can be taken.

  According to a fourth aspect of the present invention, in the exhaust gas purification system for a working machine according to any one of the first to third aspects, the adjustment valve means is configured to operate by pulse width modulation control. The possibility that the pressure on the hydraulic pump side suddenly increases or decreases can be suppressed. For this reason, it is possible to prevent the engine output from changing suddenly and reduce the shock (shock) caused by the engine output sudden change.

It is a side view of a backhoe carrying an engine. It is a top view of a backhoe. It is fuel system explanatory drawing of an engine. It is a functional block diagram which shows the relationship between an engine and an exhaust gas purification apparatus. It is a figure explaining the injection timing of fuel. It is explanatory drawing of an output characteristic map. It is explanatory drawing of an instrument panel. It is a flowchart which shows the flow of DPF regeneration control. It is a flowchart which shows another example of DPF regeneration control. It is a functional block diagram which shows another example of an adjustment valve means. (A) is a drive output diagram of an electromagnetic switching valve when shifting to a pilot pressure application state, (b) is an explanatory diagram showing the relationship between the achieved duty ratio and time in this case, and (c) is a pilot pressure discharge state (D) is an explanatory diagram showing the relationship between the achieved duty ratio and time in this case.

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

(1). First, a schematic structure of a backhoe 141, which is an example of a working machine on which the engine 70 is mounted, will be described with reference to FIGS. 1 and 2. In FIG. 2, the illustration of the cabin 6 is omitted for convenience of explanation.

  A backhoe 141, which is an example of a work machine, includes a crawler type traveling device 142 having a pair of left and right traveling crawlers 143 (shown only on the left side in FIG. 1), and a swivel base 144 (airframe) provided on the traveling device 142. I have. The swivel 144 is configured to be capable of horizontal swivel over all 360 ° directions with a swivel motor (not shown). An earth discharging plate 145 is attached to the front portion of the traveling device 142 so as to be rotatable up and down.

  On the swivel base 144, a cabin 146 as a control unit and a diesel four-cylinder type engine 70 are mounted. A working unit 150 having a boom 151, an arm 152, and a bucket 153 for excavation work is provided at the front of the swivel base 144. As shown in FIG. 2, a cabin 146 includes a control seat 148 on which an operator is seated, a throttle lever 166 as throttle operation means for setting and maintaining the engine speed, and a lever / switch group as work unit operation means. 167 to 170 (a turning operation lever 167, an arm operation lever 168, a bucket operation switch 169, and a boom operation lever 170) are arranged.

  The boom 151 which is a constituent element of the working unit 150 is formed in a shape that protrudes forward at the front end side and is bent in a letter shape in a side view. A base end portion of the boom 151 is pivotally attached to a boom bracket 154 attached to the front portion of the swivel base 144 so as to be swingable about a horizontal boom shaft 155. On the inner surface (front surface) side of the boom 151, a one-rod double-acting boom cylinder 156 for swinging it up and down is disposed. The cylinder side end of the boom cylinder 156 is pivotally supported by the front end of the boom bracket 154 so as to be rotatable. The rod side end of the boom cylinder 156 is pivotally supported by a front bracket 157 fixed to the front surface side (dent side) of the bent portion of the boom 151.

  A base end portion of a long-angle cylindrical arm 152 is pivotally attached to a distal end portion of the boom 151 so as to be swingable about a lateral arm shaft 159. A single-rod double-acting arm cylinder 160 for swinging and swinging the arm 152 is arranged on the front upper surface side of the boom 151. The cylinder side end of the arm cylinder 160 is pivotally supported by a rear bracket 158 that is fixed to the back side (protrusion side) of the bent portion of the boom 151. The rod side end portion of the arm cylinder 160 is pivotally supported by an arm bracket 161 fixed to the outer surface (front surface) of the base end side of the arm 152.

  A bucket 153 as an excavation attachment is pivotally attached to the distal end portion of the arm 152 so as to be swiveled around a lateral bucket shaft 162. On the outer surface (front surface) side of the arm 152, a one-rod double-acting bucket cylinder 163 for scooping and rotating the bucket 153 is disposed. The cylinder side end of the bucket cylinder 163 is pivotally supported by the arm bracket 161 so as to be rotatable. The rod side end of the bucket cylinder 163 is pivotally supported by the bucket 153 via a connection link 164 and a relay rod 165.

(2). Next, the structure of the engine 70 and its surroundings will be described with reference to FIGS. 3 and 4. As shown in FIG. 4, the engine 70 is a four-cylinder diesel engine as described above, and includes a cylinder block 75 to which a cylinder head 72 is fastened. An intake manifold 73 is connected to one side of the cylinder head 72, and an exhaust manifold 71 is connected to the other side. A common rail system 117 that supplies fuel to each cylinder of the engine 70 is provided below the intake manifold 73 on the side surface of the cylinder block 75. An intake pipe 76 connected to the intake upstream side of the intake manifold 73 is connected to an intake throttle device 81 and an air cleaner (not shown) for adjusting the intake pressure (intake amount) of the engine 70.

  As shown in FIG. 3, a fuel tank 118 is connected to the injectors 115 for four cylinders in the engine 70 via a common rail system 117 and a fuel supply pump 116. Each injector 115 is provided with an electromagnetic switching control type fuel injection valve 119. The common rail system 117 includes a cylindrical common rail 120. A fuel tank 118 is connected to the suction side of the fuel supply pump 116 via a fuel filter 121 and a low pressure pipe 122. The fuel in the fuel tank 118 is sucked into the fuel supply pump 116 via the fuel filter 121 and the low pressure pipe 122. The fuel supply pump 116 of the embodiment is disposed in the vicinity of the intake manifold 73. On the other hand, a common rail 120 is connected to the discharge side of the fuel supply pump 116 via a high-pressure pipe 123. The common rail 120 is connected to injectors 115 for four cylinders via four fuel injection pipes 126.

  In the above configuration, the fuel in the fuel tank 118 is pumped to the common rail 120 by the fuel supply pump 116, and high-pressure fuel is stored in the common rail 120. Each fuel injection valve 119 is controlled to open and close, whereby high-pressure fuel in the common rail 120 is injected from each injector 115 to each cylinder of the engine 70. That is, by electronically controlling each fuel injection valve 119, the injection pressure, injection timing, and injection period (injection amount) of the fuel supplied from each injector 115 are controlled with high accuracy. Therefore, nitrogen oxide (NOx) from the engine 70 can be reduced, and noise and vibration of the engine 70 can be reduced.

  As shown in FIG. 5, the common rail system 117 is configured to execute the main injection A near the top dead center (TDC). In addition to the main injection A, the common rail system 117 executes a small amount of pilot injection B for the purpose of reducing NOx and noise at the time of the crank angle θ1 about 60 ° before the top dead center, Pre-injection C is executed for the purpose of noise reduction immediately before the crank angle θ2, and particulate matter (hereinafter referred to as PM) is reduced and exhaust gas is emitted at the crank angles θ3 and θ4 after top dead center. The after-injection D and the post-injection E are executed for the purpose of promoting purification.

  As shown in FIG. 3, a fuel supply pump 116 is connected to the fuel tank 118 via a fuel return pipe 129. A common rail return pipe 131 is connected to the end of the cylindrical common rail 120 in the longitudinal direction via a return pipe connector 130 that limits the pressure of fuel in the common rail 120. That is, surplus fuel from the fuel supply pump 116 and surplus fuel from the common rail 120 are collected in the fuel tank 118 via the fuel return pipe 129 and the common rail return pipe 131.

  An exhaust pipe 77 connected to the exhaust downstream side of the exhaust manifold 71 includes an exhaust throttle device 82 for adjusting the exhaust pressure of the engine 70 and a diesel particulate filter 50 (hereinafter referred to as DPF) which is an example of an exhaust gas purification device. Connected). Exhaust gas discharged from each cylinder to the exhaust manifold 71 is purified through the exhaust pipe 77, the exhaust throttle device 82, and the DPF 50, and then released to the outside.

  The DPF 50 is for collecting PM or the like in the exhaust gas. The DPF 50 according to the embodiment is configured by accommodating a diesel oxidation catalyst 53 such as platinum and a soot filter 54 in series in a substantially cylindrical filter case 52 in a casing 51 made of a refractory metal material. In the embodiment, the diesel oxidation catalyst 53 is disposed on the exhaust upstream side of the filter case 52, and the soot filter 54 is disposed on the exhaust downstream side. The soot filter 54 has a honeycomb structure having a large number of cells partitioned by porous (filterable) partition walls.

  An exhaust introduction port 55 that communicates with the exhaust downstream side of the exhaust throttle device 82 in the exhaust pipe 76 is provided on one side of the casing 51. One end of the casing 51 is closed by a first bottom plate 56, and one end of the filter case 52 facing the first bottom plate 56 is closed by a second bottom plate 57. The annular gap between the casing 51 and the filter case 52 and the gap between the bottom plates 56 and 57 are filled with a heat insulating material 58 such as glass wool so as to surround the diesel oxidation catalyst 53 and the soot filter 54. ing. The other side of the casing 51 is closed by two lid plates 59 and 60, and a substantially cylindrical exhaust outlet 61 passes through both the lid plates 59 and 60. In addition, a resonance chamber 63 that communicates with the inside of the filter case 52 via a plurality of communication pipes 62 is provided between the lid plates 59 and 60.

  An exhaust gas introduction pipe 65 is inserted into an exhaust introduction port 55 formed on one side of the casing 51. The tip of the exhaust gas introduction pipe 65 projects across the casing 51 to the side surface opposite to the exhaust introduction port 55. A plurality of communication holes 66 opening toward the filter case 52 are formed on the outer peripheral surface of the exhaust gas introduction pipe 65. A portion of the exhaust gas introduction pipe 65 that protrudes from the side surface opposite to the exhaust introduction port 55 is closed by a lid 67 that is detachably screwed to the portion.

  The DPF 50 is provided with a DPF temperature sensor 26 that detects an exhaust gas temperature in the DPF 50 as an example of a detection unit. The DPF temperature sensor 26 of the embodiment is mounted through the casing 51 and the filter case 52, and the tip thereof is located between the diesel oxidation catalyst 53 and the soot filter 54.

  Further, the DPF 50 is provided with a differential pressure sensor 68 that detects a clogged state of the soot filter 54 as an example of a detection unit. The differential pressure sensor 68 of the embodiment detects a pressure difference (differential pressure) between the upstream and downstream sides of the soot filter 54 in the DPF 50. In this case, the upstream side exhaust pressure sensor 68 a constituting the differential pressure sensor 68 is attached to the lid 67 of the exhaust gas introduction pipe 65, and the downstream side exhaust pressure sensor 68 b is interposed between the soot filter 54 and the resonance chamber 63. It is installed. It is well known that there is a certain law between the pressure difference between the upstream and downstream of the DPF 50 and the amount of PM accumulated in the DPF 50. In the embodiment, the PM accumulation amount in the DPF 50 is estimated from the pressure difference detected by the differential pressure sensor 68, and the adjustment valve means 100 and the common rail 120 described later are operated based on the estimation result, soot filter 54. Regeneration control (DPF regeneration control) is executed.

  The clogged state of the soot filter 54 is not limited to the differential pressure sensor 68 but may be an exhaust pressure sensor that detects the pressure upstream of the soot filter 54 in the DPF 50. When the exhaust pressure sensor is adopted, the pressure (reference pressure) on the upstream side of the soot filter 54 when PM is not deposited on the soot filter 54 is compared with the current pressure detected by the exhaust pressure sensor. As a result, the clogged state of the soot filter 54 is determined.

  In the above configuration, the exhaust gas from the engine 5 enters the exhaust gas introduction pipe 65 via the exhaust introduction port 55 and is ejected into the filter case 52 from each communication hole 66 formed in the exhaust gas introduction pipe 65. After being dispersed over a wide area in the filter case 52, the diesel oxidation catalyst 53 and the soot filter 54 are passed through in this order for purification. At this stage, PM in the exhaust gas is collected without passing through the porous partition wall between the cells in the soot filter 54. Thereafter, exhaust gas that has passed through the diesel oxidation catalyst 53 and the soot filter 54 is discharged from the exhaust outlet 61.

When exhaust gas passes through the diesel oxidation catalyst 53 and the soot filter 54, if the exhaust gas temperature exceeds the regeneration boundary temperature (for example, about 300 ° C.), the action of the diesel oxidation catalyst 53 causes NO in the exhaust gas. (Nitric oxide) is oxidized to unstable NO ₂ (nitrogen dioxide). Then, the PM trapping ability of the soot filter 54 is recovered (DPF 50 is regenerated) by oxidizing and removing the PM deposited on the soot filter 54 with O (oxygen) released when NO ₂ returns to NO. become.

  As shown in FIG. 4, a working unit hydraulic pump 101 and a pilot pump 102 that are driven by the rotational power of an output shaft 80 (crankshaft) protruding from the engine 70 are provided on one side of the engine 70. Yes. The working unit hydraulic pump 101 is of a variable displacement type that supplies hydraulic oil to an arm cylinder 160 and a bucket cylinder 163 as hydraulic actuators. The pilot pump 102 is of a fixed capacity type that applies pilot pressure to an electromagnetic switching valve 106 described later.

  The suction side of the working unit hydraulic pump 101 is connected to the hydraulic oil tank 108. The discharge side of the working unit hydraulic pump 101 is connected to the working unit hydraulic circuit 103 via a pressure regulating valve 104 with a back pressure mechanism 105 described later. Needless to say, an arm cylinder 160 and a bucket cylinder 163 as hydraulic actuators are arranged in the working unit hydraulic circuit 103. The suction side of the pilot pump 102 is connected to the hydraulic oil tank 108. The discharge side of the pilot pump 102 is connected to the pump-side first port 106 a of the electromagnetic switching valve 106.

  The pressure regulating valve 104 is used to keep the pressure and flow rate on the working unit hydraulic circuit 103 side constant and to switch the pressure on the working unit hydraulic pump 101 side in two stages. The pressure regulating valve 104 according to the embodiment has a normal state in which there is no pressure increase on the working unit hydraulic pump 101 side and a working unit hydraulic pump 101 side by the elastic force of the spring 105c via the piston 105b in the back pressure mechanism 105. The drive is switched to a high pressure state in which the pressure is increased by a predetermined pressure.

  The electromagnetic switching valve 106 is a three-port two-position switching type that adds pilot pressure from the pilot pump 102 to the back pressure mechanism 105 of the pressure regulating valve 104. The electromagnetic switching valve 106 of the embodiment is configured such that the pilot pressure is applied to the back pressure chamber 105a of the back pressure mechanism 105 and the pilot pressure from the back pressure chamber 105a by excitation of an electromagnetic solenoid 107 based on control information from the ECU 11 described later. It is configured to be switched to the discharge state.

  As described above, the pump-side first port 106 a of the electromagnetic switching valve 106 is connected to the discharge side of the pilot pump 102. The pump-side second port 106 b of the electromagnetic switching valve 106 is connected to the hydraulic oil tank 108. The back pressure side port 106 c of the electromagnetic switching valve 106 is connected to the back pressure chamber 105 a of the back pressure mechanism 105. When the electromagnetic switching valve 106 is switched to the pilot pressure application state, the hydraulic oil from the pilot pump 102 via the electromagnetic switching valve 106 flows into the back pressure chamber 105a of the back pressure mechanism 105 and compresses the spring 105c via the piston 105b. Then, the pressure adjusting valve 104 is switched to a high pressure state in which the pressure on the working unit hydraulic pump 101 side is increased by a predetermined pressure.

  Then, due to the action of the pressure adjusting valve 104, a dummy load is applied to the working unit hydraulic pump 101, and the discharge pressure (which may be referred to as an operation amount or a load) of the working unit hydraulic pump 101 increases. As a result, the engine load increases. As a result, the engine output (fuel injection amount) increases to maintain the set rotational speed by the throttle lever 166, and the exhaust gas temperature rises.

  When the electromagnetic switching valve 106 is driven to switch to the pilot pressure discharge state, hydraulic oil flows out from the back pressure chamber 105a of the back pressure mechanism 105, the spring 105c expands by its own elastic restoring force, and the action of the pressure adjustment valve 104 The discharge pressure of the working unit hydraulic pump 101 decreases to the normal state. Along with this, the engine load is reduced. In this case, since the working oil having substantially the same pressure and flow rate is supplied to the working unit hydraulic circuit 103 side as when the pressure regulating valve 104 is not provided, the working unit hydraulic circuit 103 due to the presence of the pressure regulating valve 104 is supplied. The impact is minimized.

  A combination of the pressure regulating valve 104 and the electromagnetic switching valve 106 corresponds to the regulating valve means 100. Note that the electromagnetic switching valve 106 is normally (when there is no control command from the ECU 11), in order to smoothly circulate and supply hydraulic oil between the working unit hydraulic pump 101 and the working unit hydraulic circuit 103, the pilot pressure Ejected. Therefore, the pressure regulating valve 104 is normally in a normal state in which there is no pressure increase on the working unit hydraulic pump 101 side.

(3). Configuration Related to Engine Control Next, a configuration related to control of the engine 70 will be described with reference to FIGS. 3, 6, and 7. As shown in FIG. 3, the ECU 70 is provided with an ECU 11 that operates a fuel injection valve 119 of each cylinder in the engine 70. The ECU 11 includes a CPU 31 that executes various arithmetic processes and controls, a ROM 32 that stores various data fixedly in advance, an EEPROM 33 that stores control programs and various data in a rewritable manner, and temporarily stores control programs and various data. RAM 34, a timer 35 for time measurement, an input / output interface, and the like, which are arranged in the engine 70 or in the vicinity thereof.

  On the input side of the ECU 11, at least a rail pressure sensor 12 that detects the fuel pressure in the common rail 120, an electromagnetic clutch 13 that rotates or stops the fuel pump 116, and a rotation speed N (crankshaft camshaft position) of the engine 70 are detected. The engine speed sensor 14 that performs the injection, the injection setter 15 that detects and sets the number of fuel injections of the injector 115 (the number of fuel injections during one stroke), the throttle position sensor 16 that detects the operating position of the throttle lever 166, and the intake path An intake air temperature sensor 17 for detecting the intake air temperature of the engine, an exhaust gas temperature sensor 18 for detecting the exhaust gas temperature in the exhaust passage, a coolant temperature sensor 19 for detecting the coolant temperature of the engine 70, and the fuel temperature in the common rail 120 are detected. Regeneration for selecting whether or not the fuel temperature sensor 20 and the DPF 50 can be regenerated. The regenerative switch 21 as the input means, the differential pressure sensor 68 (upstream exhaust pressure sensor 68a and downstream exhaust pressure sensor 68b), the DPF temperature sensor 26 for detecting the exhaust gas temperature in the DPF 50, and the like are connected. .

  At the output side of the ECU 11, electromagnetic solenoids of the fuel injection valves 119 for at least four cylinders are respectively connected. That is, the high-pressure fuel stored in the common rail 120 is injected from the fuel injection valve 119 in a plurality of times during one stroke while controlling the fuel injection pressure, the injection timing, the injection period, and the like, so that nitrogen oxide (NOx ), And complete combustion with reduced generation of PM, carbon dioxide, and the like is performed to improve fuel efficiency.

  Further, on the output side of the ECU 11, an intake throttle device 81 for adjusting the intake pressure (intake amount) of the engine 70, an exhaust throttle device 82 for adjusting the exhaust pressure of the engine 70, and a failure notification of the ECU 11 are notified. The ECU malfunction lamp 22, the exhaust temperature warning lamp 23 serving as an abnormally high temperature notification means for reporting an abnormally high temperature of the exhaust gas in the DPF 50, the regeneration lamp 24 that is turned on when the DPF 50 is regenerated, and the drive of the electromagnetic switching valve 106 are controlled. An electromagnetic solenoid 107 or the like is connected. Data relating to blinking of the lamps 22 to 24 is stored in the EEPROM 33 of the ECU 11 in advance. As will be described in detail later, the regeneration lamp 24 serves as a regeneration notification means that operates when the clogged state of the DPF 50 exceeds a specified level or exceeds a limit level, and serves as a regeneration notification means for notifying that the DPF 50 regeneration operation is being performed. It constitutes a single indicator that also serves as a role. As shown in FIGS. 2 and 7, the regeneration switch 21 and the lamps 22 to 24 are provided on the instrument panel 40 in the working machine (backhoe 141) to be mounted with the engine 70.

  The regeneration switch 21 is of an alternate operation type. That is, the playback switch 21 is a lock-type push switch that is locked at the pressed position when pressed once and returns to the original position when pressed again. If the regeneration switch 21 is locked in the depressed position when the regeneration lamp 24 flashes to notify that the clogged state of the DPF 50 has reached a specified level, it can be shifted to each mode described later.

  In the EEPROM 33 of the ECU 11, an output characteristic map M (see FIG. 6) indicating the relationship between the rotational speed N of the engine 70 and the torque T (load) is stored in advance. The output characteristic map M is obtained by experiments or the like. In the output characteristic map M shown in FIG. 6, the rotational speed N is taken on the horizontal axis and the torque T is taken on the vertical axis. The output characteristic map M is a region surrounded by a solid line Tmx drawn upwardly. A solid line Tmx is a maximum torque line representing the maximum torque for each rotational speed N. In this case, if the model of the engine 70 is the same, the output characteristic maps M stored in the ECU 11 are all the same (common). As shown in FIG. 6, the output characteristic map M is divided vertically by a boundary line BL representing the relationship between the rotational speed N and the torque T when the exhaust gas temperature is the regeneration boundary temperature (about 300 ° C.). . The upper region across the boundary line BL is a reproducible region in which PM deposited on the soot filter 54 can be oxidized and removed (the oxidizing action of the oxidation catalyst 53 works), and the lower region is not oxidized and removed of PM. This is a non-reproducible region that accumulates on the soot filter 54.

  The ECU 11 basically calculates the torque T based on the output characteristic map M, the rotational speed N detected by the engine speed sensor 14, and the throttle position detected by the throttle position sensor 16 and performs target fuel injection. The fuel injection control for obtaining the amount and operating the common rail system 117 based on the calculation result is executed. Here, the fuel injection amount is adjusted by adjusting the valve opening period of each fuel injection valve 119 and changing the injection period to each injector 115.

(4). Aspects of DPF regeneration control Next, an example of DPF regeneration control by the ECU 11 will be described with reference to the flowchart of FIG. As a control mode of the engine 70 (a control format related to DPF regeneration), at least when a normal operation mode for running on the road and various operations and when the clogged state of the DPF 50 exceeds a specified level, exhaust is performed when the regeneration switch 21 is pressed. There are a manual auxiliary regeneration mode in which the gas temperature is raised and a forced regeneration mode in which fuel is supplied into the DPF 50 by post injection E.

  In the manual auxiliary regeneration mode, by adjusting the pressure of the pressure adjusting valve 104 based on the detection information of the differential pressure sensor 68, the discharge pressure of the working unit hydraulic pump 101 is increased and the engine load is indirectly increased. Then, as the engine load increases, the engine output (fuel injection amount) is increased, and the exhaust gas temperature from the engine 70 is increased. As a result, PM in the DPF 50 (soot filter 54) can be burned and removed.

  The forced regeneration mode is executed when the clogged state of the DPF 50 is not improved even though the clogged state of the DPF 50 is not less than a specified level and the non-pressed state of the regeneration switch 21 continues for a long time. In the forced regeneration mode, fuel is supplied into the DPF 50 by post-injection E, and the fuel is combusted by the diesel oxidation catalyst 53, thereby increasing the exhaust gas temperature in the DPF 50 (about 560 ° C.). As a result, the PM in the DPF 50 (soot filter 54) can be forcibly burned and removed.

  As shown in FIG. 8, each of the above modes is executed based on a command from the ECU 11. That is, the algorithm shown in the flowchart of FIG. 8 is stored in the EEPROM 33. Each mode described above is executed by calling the algorithm to the RAM 34 and then processing the CPU 31.

  As shown in the flowchart of FIG. 8, in the DPF 50 regeneration control, first, the PM accumulation amount in the DPF 50 is estimated based on the detection result from the differential pressure sensor 68, and whether or not the estimation result is equal to or greater than a specified amount (specified level). When the determination is made (S01) and it is determined that the PM accumulation amount is equal to or greater than the specified amount (S01: NO), measurement based on the time information of the timer 35 is started and the regeneration lamp 24 is blinked at a low speed (S02). Notice the execution of the replay operation (manual auxiliary replay mode). The prescribed amount in the embodiment is set to 8 g / l, for example. The blinking frequency of the reproduction lamp 24 is set to 1 Hz, for example.

  Next, it is determined whether or not the regeneration switch 21 is depressed (S03). If the regeneration switch 21 is not locked in the depressed state (S03: OFF), a predetermined time (for example, about 30 minutes) has elapsed since the regeneration lamp 24 started blinking slowly. Is determined (S04). If the predetermined time has not elapsed (S04: NO), the process returns to step S03. In steps S03 to S04, the control mode of the engine 70 remains in the normal operation mode even though the PM accumulation amount is not less than the specified amount, and the current driving state of the engine 70 is maintained. That is, the transition to the manual auxiliary regeneration mode (which may be referred to as the DPF 50 regeneration operation) is prohibited. The blinking cycle of the regeneration lamp 24 is set to be shorter as the PM accumulation amount in the DPF 50 increases (the regeneration lamp 24 blinks at shorter intervals as the PM accumulation amount in the DPF 50 increases). For this reason, the operator's attention can be alerted by the flashing speed of the regeneration lamp 24.

  When the predetermined time has elapsed in step S04 (S04: YES), it is assumed that the PM accumulation amount is equal to or greater than the predetermined amount, and it is assumed that the regeneration switch 21 is left unattended for a long time. After the regeneration lamp 24 is turned on (S05), the forced regeneration mode is executed (S06). In the forced regeneration mode, as described above, the fuel is supplied into the DPF 50 by the post-injection E of the common rail system 117, and the fuel is burned by the diesel oxidation catalyst 53, whereby the exhaust gas temperature in the DPF 50 is raised. As a result, the PM in the DPF 50 is forcibly burned and removed, and the PM collection capability of the DPF 50 is restored. The forced regeneration mode of step S06 is executed for about 15 minutes, for example, and after the elapse of the time (S07: YES), the common rail system 117 ends the post injection E (S08), and turns off the regeneration lamp 24 (S09). The end of forced regeneration mode is notified.

  Now, returning to step S03, if the regeneration switch 21 is locked in the depressed state (S03: ON), then the regeneration lamp 24 blinking at a low speed is turned on (S10), and the transition time from when the regeneration switch 21 is depressed. After Tt has elapsed (S11: YES), the manual auxiliary regeneration mode is executed (S12).

  The data of the transition time Tt is stored in advance in the ROM 192 of the ECU 11, for example. When the ROM 32 and the EEPROM 33 are accessed for the first time, that is, when the backhoe 141 (work machine) is turned on for the first time, the ROM 32 and the EEPROM 33 are electrically connected. Is written (copied) to the EEPROM 33 side. The data of the transition time Tt can be changed. Specifically, the data of the transition time Tt stored on the EEPROM 33 side can be rewritten later by using an external tool 39 (see FIG. 3) such as a ROM writer connected to the ECU 11 via a communication terminal line.

  In the manual auxiliary regeneration mode in step S12, the electromagnetic solenoid 107 of the electromagnetic switching valve 106 is excited to switch the electromagnetic switching valve 106 to the pilot pressure application state. Then, the pressure regulating valve 104 is switched to a high pressure state in which the pressure on the working unit hydraulic pump 101 side is increased by a predetermined pressure by the action of the back pressure mechanism 105, and a dummy load is applied to the working unit hydraulic pump 101. The discharge pressure of the working unit hydraulic pump 101 increases. Accordingly, the engine load increases by an amount corresponding to the dummy load, and the engine output increases and the exhaust gas temperature rises to maintain the set rotational speed by the throttle lever 166. As a result, the PM in the DPF 50 is burned and removed, and the PM collection ability of the DPF 50 is restored.

  Next, in step S13, the PM accumulation amount in the DPF 50 is estimated again, and it is determined whether or not the estimation result is equal to or less than an allowable amount (allowable level). The allowable amount (allowable level) is set to be smaller (lower) than the above-mentioned specified amount (specified level). The allowable amount of the embodiment is set to 4 g / l, for example. If the PM accumulation amount is equal to or less than the allowable amount (S13: YES), the electromagnetic switching valve 106 is returned to the pilot pressure discharge state by the excitation of the electromagnetic solenoid 107, and the pressure adjustment valve 104 is switched to the normal state and driven. The discharge pressure of the hydraulic pump 101 is reduced to the original state (S14). Then, the regeneration lamp 24 is turned off (S15) to notify the end of the manual auxiliary regeneration mode. If the PM accumulation amount exceeds the allowable amount in step S13 (S13: NO), the PM in the DPF 50 is not yet sufficiently burned and removed, and the process returns to step S12.

  As shown in another example of FIG. 9, when the manual auxiliary regeneration mode is executed for a set time Tw (for example, about 20 minutes) or more, the discharge pressure of the working unit hydraulic pump 101 is reduced to the original state and the regeneration is performed. The lamp 24 may be turned off to notify the end of the manual auxiliary regeneration mode. That is, in step S13, instead of determining the allowable amount, it may be determined whether or not the elapsed time since the pressure adjustment valve 104 is operated is equal to or longer than a preset set time Tw. This is because if the state in which the exhaust gas temperature is raised continues for the set time Tw, it is normally considered that the clogged state of the DPF 50 has been sufficiently improved. The aforementioned set time Tw is measured based on the time information of the timer 35, for example, from the start of operation of the pressure adjustment valve 104.

  FIG. 10 shows another example of the regulating valve means 100. In the other example, the ON / OFF control type electromagnetic switching valve 106 illustrated in the previous embodiment is changed to a pilot pressure adjusting electromagnetic valve 106 ′ capable of adjusting the hydraulic oil supply pressure to the back pressure chamber 105a. . The adjustment pressure on the working part hydraulic pump 101 side in the pressure adjustment valve 104 is adjusted according to the hydraulic oil supply pressure via the pilot pressure adjustment electromagnetic valve 106 ′. In this case, the pilot pressure adjusting electromagnetic valve 106 'is operated by pulse width modulation control (PWM control) (see FIGS. 11A to 11D).

  That is, as shown in FIGS. 11 (a) and 11 (b), during the control time period δT, the pulse width τ (energization time) is gradually increased so that the arrival duty ratio D (τ / T: T is a switching cycle) is increased. The drive signal is intermittently transmitted to the electromagnetic solenoid 107 'of the pilot pressure adjusting electromagnetic valve 106' so as to gradually increase. In this case, the ultimate duty ratio D apparently increases linearly from 0% to 100% with a positive slope as time elapses.

  Further, as shown in FIGS. 11C and 11D, during the control time period δT, the drive signal is sent to the electromagnetic solenoid 107 ′ so that the pulse width τ is gradually decreased and the ultimate duty ratio D is gradually decreased. Is transmitted intermittently. In this case, the ultimate duty ratio D apparently decreases linearly from 100% to 0% with a negative slope as time passes.

  That is, the pilot pressure adjusting electromagnetic valve 106 ′ and thus the pressure adjusting valve 104 are smoothly operated by the pulse width modulation control, thereby suppressing the discharge pressure of the working unit hydraulic pump 101 from rapidly increasing or decreasing. Therefore, it is possible to prevent the engine output from changing suddenly, and to reduce the shock (shock) caused by the engine output sudden change. Using the pulse width modulation control, the pressure adjustment operation of the pressure adjustment valve 104 can be performed with high reliability without being significantly affected by the hydraulic oil temperature. Further, the adjustment pressure of the pressure adjustment valve 104, and hence the engine load increase (dummy load) can be adjusted arbitrarily, which is effective in suppressing fuel consumption deterioration associated with DPF regeneration control.

(5). Summary As is apparent from the above description and FIGS. 3 and 8, the exhaust gas purification device 50 disposed in the exhaust path 77 of the engine 70, the hydraulic actuators 160 and 163, and the hydraulic actuator with the power of the engine 70. And a hydraulic pump 101 for supplying hydraulic oil to 160 and 163, and a regulating valve means 100 disposed between the hydraulic pump 101 and a working unit hydraulic circuit 103 on the downstream side thereof, and the exhaust gas purification When the clogged state of the device 50 exceeds a specified level, the pressure on the hydraulic pump 101 side is increased by the operation of the adjusting valve means 100, thereby increasing the engine load while maintaining the engine speed. Therefore, for example, the setting of the fuel injection control of the engine 70 and the open / close control of the intake and exhaust throttle devices 81 and 82 are changed. Without this, the exhaust gas purification device 50 can be regenerated by increasing the engine output and increasing the exhaust gas temperature by increasing the pressure on the hydraulic pump 101 side. That is, the particulate matter collecting ability of the exhaust gas purifying device 50 can be recovered.

  As apparent from the above description and FIGS. 3, 8 and 10, the clogged state of the exhaust gas purifying device 50 falls below an allowable level lower than the specified level, or the adjustment valve means 100 is operated. When the elapsed time after the time becomes equal to or longer than a preset time Tw, it can be considered that the clogged state of the exhaust gas purifying device 50 has been improved, so the pressure increase on the hydraulic pump 101 side by the adjusting valve means 100 By releasing the, it is possible to prevent the adjustment valve means 100 from being inactivated and to prevent an excessive load from being applied to the engine 70 from the hydraulic pump 101 without depending on an operator's return operation or the like. Therefore, the efficiency of the regeneration operation of the exhaust gas purification device 50 can be improved, and the deterioration of fuel consumption accompanying the regeneration of the exhaust gas purification device 50 can be suppressed.

  As is clear from the above description and FIGS. 3 and 8, the transition time Tt until the regulating valve means 100 is changed from the non-operating state to the operating state can be changed. Accordingly, the transition time Tt can be set. For this reason, when the exhaust gas purification device 50 is regenerated, a fine measure can be taken.

  As is apparent from the above description and FIGS. 10 and 11, since the regulating valve means 100 is configured to operate by pulse width modulation control, there is a risk that the pressure on the hydraulic pump 101 side suddenly increases or decreases. Can be suppressed. For this reason, it is possible to prevent the engine output from changing suddenly and reduce the shock (shock) caused by the engine output sudden change.

(6). Others The present invention is not limited to the above-described embodiment, and can be embodied in various forms. The configuration of each part is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the pilot pump 102 is eliminated, the electromagnetic switching valve 106 or the pilot pressure adjusting electromagnetic valve 106 ′ is connected to the discharge side of the working unit hydraulic pump 101, and the pressure adjusting valve 104 is discharged from the working unit hydraulic pump 101. You may control by the self-pressure of hydraulic oil. In this case, since the number of necessary pumps is small, the configuration is simplified and the manufacturing cost can be reduced.

11 ECU
50 DPF (Exhaust Gas Purifier)
70 Engine 100 Adjusting valve means 101 Working part hydraulic pump 102 Pilot pump 103 Working part hydraulic circuit 104 Pressure adjusting valve 105 Back pressure mechanism 106 Electromagnetic switching valve 106 'Pilot pressure adjusting electromagnetic valve 107 Electromagnetic solenoid 108 Hydraulic oil tank 117 Common rail system 120 Common rail 141 Backhoe (work machine)
160 Arm cylinder (hydraulic actuator)
163 Bucket cylinder (hydraulic actuator)
166 Throttle lever

Claims (4)

An exhaust gas purifying device disposed in the exhaust path of the engine, a hydraulic actuator, a hydraulic pump that supplies hydraulic oil to the hydraulic actuator by the power of the engine, the hydraulic pump and a working unit hydraulic circuit downstream thereof And an adjustment valve means arranged between
The engine load is increased while maintaining the engine speed by increasing the pressure on the hydraulic pump side by the operation of the adjustment valve means when the clogged state of the exhaust gas purification device exceeds a specified level. Being
Exhaust gas purification system for work equipment. When the clogged state of the exhaust gas purifying device is lower than an allowable level lower than the specified level, or when the elapsed time since the operation of the adjusting valve unit is longer than a preset time, the adjusting valve unit Configured to release the pressure increase on the hydraulic pump side due to
The exhaust gas purification system for a working machine according to claim 1. The transition time until the regulating valve means is changed from a non-operating state to an operating state can be changed.
An exhaust gas purification system for a working machine according to claim 1 or 2. The regulating valve means is configured to operate by pulse width modulation control,
The exhaust gas purification system for a working machine according to any one of claims 1 to 3.

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