JP4990860B2 - Engine control system for work equipment - Google Patents

Description

  The present invention relates to an engine control system for a working machine such as a hydraulic excavator, and more particularly to an exhaust gas aftertreatment device (filter) that collects particulate matter contained in engine exhaust gas in a traveling work machine such as a hydraulic excavator. The present invention relates to an engine control system for a working machine equipped with a regenerator that regenerates an exhaust gas aftertreatment device by burning and removing particulate matter deposited on the machine.

  A working machine such as a hydraulic excavator, which is a typical example of a construction machine, drives a hydraulic pump by a diesel engine (hereinafter simply referred to as an engine), and drives a hydraulic actuator by pressure oil discharged from the hydraulic pump. A driven body such as an arm or a bucket is driven to perform a predetermined operation. In such a working machine, the engine rotation speed is instructed by a rotation speed instruction device (for example, an engine control dial), and the target rotation speed of the engine is set by the operator operating the rotation speed instruction device. This rotational speed indicating device is not operated during work, and the rotational speed indicated by the rotational speed indicating device is constant.

  By the way, in such a working machine such as a hydraulic excavator, when the working machine is in a predetermined operation state for the purpose of reducing fuel consumption (hereinafter, abbreviated as “fuel consumption” as appropriate) and reducing noise, Some control (engine speed reduction control) is performed to reduce the engine speed below the engine speed indicated by the engine speed instruction device. One example of such engine low speed control is auto idle control. This is because when a predetermined delay time has elapsed from the time when all the operation levers that instruct the operation of the driven body are in a neutral state, the engine speed is lower than the speed indicated by the speed indicator. It controls to rotation speed (patent document 1). As another example, there is economy mode control for controlling the engine speed in accordance with the pump discharge pressure. This is because when the discharge pressure of the hydraulic pump is lower than the pressure near the start pressure of the torque limit control of the hydraulic pump, the engine speed is set to the speed indicated by the speed indicator (usually the maximum rated speed). When the pressure is higher than the pressure near the start pressure of the torque limit control of the hydraulic pump, the engine speed is controlled to be lower than the engine speed indicated by the engine speed indicating device (Patent Document 2).

  On the other hand, exhaust gas regulations for diesel engines are becoming stricter year by year, and the PM emission amount [g / kWh] and the emission Nox amount [g / kWh] from the engine are regulated. The amount of exhausted PM is the amount of particulate matter (PM: particulate matter: hereinafter referred to as PM as appropriate) contained in the exhaust gas. In order to comply with such regulations on the amount of exhaust PM, in recent years, a DPF (Diesel Particulate Filter) is disposed as an exhaust gas after-treatment device in the exhaust system of an engine, and PM is collected and removed (patent) Reference 3). Further, in a system in which a DPF is arranged in an engine exhaust system, a regeneration device that regenerates the DPF by burning and removing PM collected by the DPF is provided (Patent Document 3).

  DPF collects PM in an internal filter to reduce PM in the exhaust gas, but the filter cannot collect PM infinitely, and if PM is collected to some extent, the filter is clogged. Therefore, it is necessary to remove PM from the filter when a certain amount of PM is collected. This PM removal method is performed by raising the internal temperature of the DPF and burning off particulate matter deposited on the filter. This is called DPF regeneration.

Japanese Patent Publication No. 60-38561 JP 2006-144705 A JP 2003-155915 A

  However, the above prior art has the following problems.

  As described in Patent Document 3, in a system having a regeneration device for an exhaust gas aftertreatment device (DPF), the internal temperature of the DPF during regeneration of the DPF rises to about 600 ° C. at which PM burns. A considerable amount of heat is generated inside the DPF. Normally, this heat is cooled by the exhaust gas flowing, and damage due to heat accumulation inside the DPF is prevented. Therefore, reducing the engine speed after regeneration is started reduces the flow rate of exhaust gas, and accordingly, the heat inside the DPF does not escape and becomes an abnormally high temperature, which may cause damage to the DPF (filter). Get higher.

  On the other hand, as described in Patent Document 1, when performing auto-idle control, when the operation lever is not operated for a certain period of time or more, the engine speed decreases below the engine speed indicated by the engine speed instruction device. As the rotational speed decreases, the exhaust gas flow rate decreases. Therefore, when an exhaust gas aftertreatment device (DPF) and a regenerator are provided on a work machine equipped with such an engine control system, auto idle control is activated during regeneration, or regeneration is performed while auto idle control is activated. When is started, the flow rate of the exhaust gas is reduced, so that the cooling performance inside the DPF is impaired, and the inside of the DPF becomes abnormally hot and there is a high possibility that the DPF will be damaged.

  As described in Patent Document 2, even when economy mode control is performed, if the discharge pressure of the hydraulic pump increases during regeneration, the engine speed decreases and the same problem occurs.

  The object of the present invention is to control the engine speed to be lower than the engine speed indicated by the engine speed instruction device in accordance with the operating state of the work implement, and to collect the DPF (exhaust gas aftertreatment device). It is an object of the present invention to provide an engine control system for a working machine that can prevent the DPF from being damaged due to a decrease in the engine speed when the particulate matter is burned and removed to regenerate the DPF.

(1) In order to achieve the above object, the present invention provides an engine, a hydraulic drive device including a hydraulic pump driven by the engine, and particulate matter that is attached to an exhaust system of the engine and contained in exhaust gas. working machine engine control system with an exhaust gas aftertreatment device, and a playback device for the trapped in the exhaust gas after-treatment device the particulate matter combustion removing play the exhaust aftertreatment device for catching , A rotation speed instruction means for instructing the rotation speed of the engine, an operation state detection means for detecting an operation state of the work implement, a mode switching means, and the mode switching means when a specific mode is selected. a row control to lower than the rotational speed of the rotational speed of the engine is the rotational speed instruction device instructs according to the the operation termination of the playback apparatus is in operation and the operating state of the working machine A first engine control unit, when the mode switching means selects the particular mode, the reproducing apparatus detects whether in operation, the first when the playback apparatus is in operation And a second engine control means for controlling the engine speed so as to invalidate the control of the engine control means and maintain the engine speed indicated by the engine speed indicating device.

By providing the first engine control means in this way, when the mode switching means selects a specific mode, the engine is controlled in accordance with the operating state of the work implement and the end of the operation of the regenerator in operation . Control can be performed to lower the rotational speed below the rotational speed indicated by the rotational speed instruction device. Further, by providing the second engine control means, when the mode switching means selects a specific mode, it is detected whether or not the playback device is operating (reproducing), and the playback device is operating. In some cases, the control of the first engine control means is invalidated, and the engine speed is controlled so as to maintain the engine speed indicated by the engine speed indicator, so the particles collected by the DPF (exhaust gas aftertreatment device) When the particulate matter is removed by combustion to regenerate the DPF, it is possible to prevent the DPF from being damaged due to a decrease in the engine speed.

(2) In the above (1), preferably, the hydraulic drive device includes a plurality of actuators driven by pressure oil from the hydraulic pump, and a flow of pressure oil supplied from the hydraulic pump to the plurality of actuators. A control valve device that controls the control valve device, and an input operation device that controls the drive of the plurality of actuators by operating the control valve device, and the operation state detection means is the input operation device as the operation state of the work implement The first engine control means detects that the input operation apparatus is operated when the mode switching means is selecting the specific mode. the response to an instruction rotational speed instruction device controls the rotational speed of the engine, operating without the input operation device is detected, and during operation Wherein the actuating end of the playback apparatus is detected that performs control to reduce the rotation speed of the rotational speed instruction device the number of revolutions of the engine is indicated, the second engine control means, said mode switching means is identified When the mode is selected and the playback device is in operation, even if it is detected that the input operation device is not operated, the rotational speed of the engine is in accordance with an instruction from the rotational speed instruction device. To control.

As a result, when the mode switching means selects a specific mode (auto idle mode), it is detected that no operation of the input operation device has been detected, and the end of operation of the playback device that is in operation is detected . Since control for reducing the rotational speed (automatic idle control) is performed, fuel consumption can be reduced and noise can be reduced. In addition, when the mode switching means selects a specific mode (auto idle mode) and the playback device is operating (playing back), even if there is no operation of the input operation device, the rotation speed instruction device Since the engine speed is controlled in accordance with this instruction, it is possible to prevent the DPF from being damaged due to a decrease in the engine speed during regeneration.

(3) In the above (1), preferably, the hydraulic drive device includes a plurality of actuators driven by pressure oil from the hydraulic pump, and pressure oil supplied from the hydraulic pump to the plurality of actuators. A control valve device for controlling the flow; an input operation device for controlling the driving of the plurality of actuators by operating the control valve device; and an absorption torque of the hydraulic pump based on a discharge pressure of the hydraulic pump. A torque control regulator that controls the capacity of the hydraulic pump so as not to exceed a maximum absorption torque that is set depending on the number of rotations of the hydraulic pump, and the operating state detecting means is an operating state of the working machine. A pressure detection device for detecting a discharge pressure, wherein the first engine control means includes a mode switching means; When a specific mode is selected, when the discharge pressure of the hydraulic pump detected by the pressure detector is lower than a predetermined pressure, the engine speed is controlled in accordance with an instruction from the engine speed indicator. , when the discharge pressure of the hydraulic pump detected by said pressure detecting device is the predetermined pressure or more Do Ri, and operation completion of the reproduction apparatus is in operation is detected, the rotational speed of the rotational speed of the engine The second engine control means performs control to reduce the rotational speed indicated by the instruction device, and when the mode switching means selects a specific mode and the playback device is in operation, the second engine control means Even when the discharge pressure of the hydraulic pump detected by the pressure detector is equal to or higher than the predetermined pressure, the engine speed is controlled in accordance with an instruction from the engine speed indicator.

As a result, when the mode switching means selects a specific mode (new economy mode) and the discharge pressure of the hydraulic pump is low, the engine speed is controlled in accordance with the instruction from the engine speed indicating device. Work can be performed at the same flow rate (working speed) as the mode, and work efficiency can be improved. Further, when the discharge pressure of the hydraulic pump rises to a predetermined pressure or more and the completion of the operation of the regenerating device that is in operation is detected , the engine speed is controlled to be low, so that the fuel consumption can be improved. Further, when the mode switching means selects a specific mode (new economy mode) and the regenerator is operating (regenerating), even if the discharge pressure of the hydraulic pump rises above a predetermined pressure Since the engine speed is controlled in accordance with an instruction from the engine speed instruction device, it is possible to prevent the DPF from being damaged due to a decrease in the engine speed during regeneration.

  (4) In the above (1) to (3), preferably, the second engine control means instructs the rotation speed instruction device until a predetermined time elapses after the operation of the regeneration device ends. In response, the engine speed is controlled.

  As a result, it is possible to prevent the DPF from being damaged by the residual heat after the end of regeneration.

  (5) Further, in the above (1) to (3), preferably, the second engine control means is configured such that when the regeneration device is operating, the engine speed indicated by the rotation speed indicating device is predetermined When the engine speed falls below the predetermined engine speed, control is performed so as to maintain the engine speed at the predetermined speed.

  As a result, even if the operator inadvertently operates the rotation speed indicating device while the playback device is operating (reproducing) and the engine speed indicated by the rotation speed indicating device is greatly decreased, the engine speed is decreased. It is possible to prevent the DPF from being damaged.

  (6) Also, in the above (1) to (3), preferably, the second engine control means is configured such that when the regeneration device is in operation and until a predetermined time elapses after the regeneration device has been activated. Controls the engine speed to be maintained at the predetermined speed when the engine speed instructed by the rotation speed indicating device falls below a predetermined speed.

  As a result, the engine speed of the engine is instructed by the operator inadvertently operating the engine speed instruction device before the predetermined time elapses during operation of the playback apparatus (during regeneration) and after the operation of the playback apparatus ends (after completion of playback). Even when the engine speed greatly decreases, it is possible to prevent the DPF from being damaged due to the decrease in the engine speed.

  According to the present invention, the engine speed can be controlled to be lower than the engine speed indicated by the engine speed instruction device in accordance with the operating state of the work implement, and is collected by the DPF (exhaust gas aftertreatment device). When the generated particulate matter is burned and removed to regenerate the DPF, it is possible to prevent the DPF from being damaged due to a decrease in the engine speed.

  Further, it is possible to prevent the DPF from being damaged due to the residual heat after the regeneration is completed.

  Furthermore, the operator inadvertently operates the rotation speed indicating device before the predetermined time elapses during operation of the reproducing device (during reproduction) or during operation of the reproducing device (during reproduction) and after completion of the operation of the reproducing device (after completion of reproduction), Even when the engine speed indicated by the engine speed indicating device is greatly reduced, it is possible to prevent the DPF from being damaged due to the engine speed being reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
~Constitution~
FIG. 1 is a diagram showing an overall system configuration of a working machine provided with an engine control system and an exhaust gas purification system in a first embodiment of the present invention. In the present embodiment, the present invention is applied to a hydraulic excavator that is a typical example of a construction machine.

  Referring to FIG. 1, a hydraulic excavator according to the present embodiment includes a hydraulic system 2 (hydraulic driving device) that drives a driven member such as a working element constituting a front working machine using a diesel engine (hereinafter simply referred to as an engine) 1 as a power source. ), An exhaust gas purification system 3 that purifies the exhaust gas of the engine 1, and an engine control system 4 that controls the rotational speed and output torque of the engine 1.

  The hydraulic system 2 includes a variable displacement main hydraulic pump 21 and a fixed displacement pilot pump 22 driven by the engine 1, and an actuator that is driven by the pressure oil discharged from the hydraulic pump 21 to drive the driven member. A control valve device 24 including a group 23, a main spool group (flow rate control valve group) for controlling the flow (flow rate and direction) of pressure oil supplied from the hydraulic pump 21 to the actuator group 23, and pressure from the pilot pump 22 And an input operation device 25 having a remote control valve group for generating a control pilot pressure for operating a main spool group of the control valve device 24 using oil as a hydraulic pressure source.

  The exhaust gas purification system 3 is disposed in an exhaust pipe 31 that constitutes an exhaust system of the engine 1, and a filter 32a that collects particulate matter (PM) contained in the exhaust gas, and an oxidation catalyst that is located upstream of the filter 32a. An exhaust gas aftertreatment device (DPF) 32 having a built-in 32b and a differential pressure detection device 33 for detecting a differential pressure across the upstream and downstream sides of the filter 32a (pressure loss of the filter 32a).

  The engine control system 4 includes an engine control dial 41 (rotation speed indicating device) for instructing the rotational speed (reference target rotational speed) of the engine 1 and a mode switching device 42 for selecting a control mode (auto idle control mode) of the engine 1. A rotation speed detection device 43 that detects the actual rotation speed of the engine 1, an operation detection device 44 that detects whether or not the input operation device 25 is operated, and a fuel supplied to the engine 1 are controlled. And an electronic governor 45 (an electronically controlled fuel injection control device).

  The vehicle body control device 51 and the engine control device 52 constitute common control means for the exhaust gas purification system 3 and the engine control system 4. The vehicle body control device 51 inputs an instruction signal from the engine control dial 41, an instruction signal from the mode switching device 42, a detection signal from the operation detection device 44, and a control signal (described later) from the engine control device 52. Then, a predetermined calculation process is performed, and a command signal for instructing the target rotational speed of the engine 1 is output to the engine control device 52. The engine control device 52 inputs a command signal from the vehicle body control device 51, a detection signal from the differential pressure detection device 33, and a detection signal from the rotation speed detection device 43, performs a predetermined calculation process, and performs an electronic governor 45. To output a control signal for instructing the target fuel injection amount. The electronic governor 45 controls the fuel injection amount supplied to the engine 1 based on the control signal so that the rotational speed of the engine 1 is maintained at the target rotational speed indicated by the command signal from the vehicle body control device 51. Control.

  FIG. 2 is a diagram showing details of the hydraulic system 2 and the operation detection device 44. The actuator group 23 of the hydraulic system 2 includes, for example, a hydraulic motor 23a and hydraulic cylinders 23b and 23c, and the control valve device 24 is, for example, pressure oil supplied from the hydraulic pump 21 to the hydraulic motor 23a and the hydraulic cylinders 23b and 23c. Pilot-operated flow control valves 24a, 24b, and 24c for controlling the flow (flow rate and direction).

  A pilot relief valve 26 is connected to the discharge oil passage 22 a of the pilot pump 22, and the pilot relief valve 26 keeps the pressure of the pressure oil discharged from the pilot pump 22 constant. The input operation device 25 is connected to the discharge oil passage 22a of the pilot pump 22, and includes a plurality of remote control valves 25a, 25b, and 25c that generate control pilot pressures a to f for operating the flow control valves 24a to 24c. .

  The remote control valves 25a and 25c are operated by the operation lever 27, and the remote control valve 25b is operated by the operation lever 28. The operation levers 27 and 28 can be operated in the cross direction. When the operating lever 27 is operated in one direction of the cross from the neutral position, the remote control valve 25a generates the control pilot pressure a, and when operated in the opposite direction of the cross from the neutral position, the remote control valve 25a generates the control pilot pressure b. The control pilot pressures a and b are guided to the corresponding pressure receiving portions of the flow control valve 24a via the respective pilot lines 29a and 29b, whereby the flow control valve 24a is switched from the neutral position. Similarly, when the operating lever 27 is operated in the other direction of the cross from the neutral position, the remote control valve 25c generates the control pilot pressure e, and when operated in the opposite direction of the cross from the neutral position, the remote control valve 25c generates the control pilot pressure f. Then, the control pilot pressures e and f are guided to the corresponding pressure receiving portions of the flow control valve 24c via the respective pilot lines 29e and 29f, whereby the flow control valve 24c is switched from the neutral position. When the operation lever 28 is operated in one direction of the cross from the neutral position, the control pilot pressure c is generated, and when the operation lever 28 is operated in the opposite direction of the cross from the neutral position, the control pilot pressure d is generated. The pilot lines 29c and 29d are led to the corresponding pressure receiving portions of the flow control valve 24b, whereby the flow control valve 24b is switched from the neutral position. When the operation lever 28 is operated in the other direction of the cross, a control pilot pressure is similarly generated, and a remote control valve (not shown) is operated.

The operation detection device 44 includes shuttle valves 44a to 44f and a pressure detection device 44g. Shuttle valve 44a is connected between pilot lines 29a and 29b of remote control valve 25a, shuttle valve 44b is connected between pilot lines 29c and 29d of remote control valve 25b, and shuttle valve 44c is between pilot lines 29e and 29f of remote control valve 25c. The shuttle valve 44d is connected between the output ports of the shuttle valves 44a and 44b, the shuttle valve 44e is connected between the output ports between the shuttle valves 44c and 44d, and the shuttle valve 44f is connected to the output port of the shuttle valve 44e. It is connected between the output ports of the final stage shuttle valve related to the remote control valve of other operating means (not shown). The pressure detection device 44g is connected to the output port of the shuttle valve 44f . As a result, the shuttle valve group including the shuttle valves 44a to 44f extracts the highest pressure among the control pilot pressures a to f of the remote control valves 25a to 25c and the control pilot pressures of the remote control valves of other operating means (not shown). The shuttle valve 44f outputs the maximum pressure, and the pressure detection device 44g detects all the operation means including the operation levers 27 and 28 of the remote control valves 25a to 25c by detecting the maximum pressure which is the output pressure of the shuttle valve 44f . Detect the presence or absence of operation.

  FIG. 3 is a diagram showing an external appearance of a hydraulic excavator including the system shown in FIG. The hydraulic excavator includes a lower traveling body 100, an upper swing body 101, and a front work machine 102. The lower traveling body 100 has left and right crawler traveling devices 103a and 103b, and is driven by left and right traveling motors 104a and 104b. The upper swing body 101 is turnably mounted on the lower traveling body 100 by the swing motor 105, and the front work machine 102 is attached to the front portion of the upper swing body 101 so as to be able to be raised and lowered. The upper swing body 101 is provided with an engine room 106 and a cabin (operating room) 107. The engine 1 is arranged in the engine room 106. , 28 are arranged.

  The front work machine 102 has an articulated structure having a boom 111, an arm 112, and a bucket 113. The boom 111 rotates in the vertical direction by expansion and contraction of the boom cylinder 114. , And the bucket 113 is rotated up and down and back and forth by the expansion and contraction of the bucket cylinder 116.

In FIG. 2, the hydraulic motor 23 a corresponds to, for example, the turning motor 105, the hydraulic cylinder 23 b corresponds to, for example, the arm cylinder 115, and the hydraulic cylinder 23 c corresponds to, for example, the boom cylinder 114. The hydraulic system 2 is also provided with other hydraulic actuators and control valves corresponding to the traveling motors 104a and 104b, the bucket cylinder 116, etc., and their operation means, but these are not shown in FIG.
~ Control content ~
FIG. 4 is a flowchart showing the filter regeneration calculation processing function of the engine control device 52. The exhaust gas purification system 3 is configured by the calculation processing function, the exhaust gas post-processing device (DPF) 32 and the differential pressure detection device 33 according to the flowchart of FIG.

  In FIG. 4, the engine control device 52 first regenerates the filter 32a of the exhaust gas aftertreatment device 32 based on the detection signal from the differential pressure detection device 33 (combustion removal of particulate matter collected by the filter 32a). Is determined (step S100). The differential pressure across the filter 32a increases as the amount of particulate matter (PM) collected by the filter 32a increases. In step S100, the pressure value of the differential pressure before and after the filter corresponding to the PM accumulation amount that needs to be regenerated based on the experimental data is set as the regeneration start determination threshold, and the filter 32a indicated by the detection signal from the differential pressure detection device 33 is set. Whether the filter 32a needs to be regenerated is determined based on whether or not the differential pressure before and after exceeds the threshold. It should be noted that a predetermined time interval may be set with a timer, and reproduction may be started periodically. If it is determined in step S100 that reproduction is not necessary, the process of step S100 is repeated. If it is determined in step S100 that reproduction is necessary, reproduction is started (step S110).

  The regeneration in step S110 is started by injecting fuel for regeneration into the exhaust pipe 31. When fuel is injected into the exhaust pipe 31, part of the injected fuel burns to raise the temperature of the exhaust gas, and unburned fuel is supplied to the oxidation catalyst 32b and oxidized by the oxidation catalyst 32b. The exhaust gas temperature further rises due to the reaction heat sometimes obtained, and the PM accumulated in the filter 32a is burned and removed by the high-temperature exhaust gas. The fuel injection for regeneration uses, for example, an in-cylinder (in-cylinder) injection system of the engine 1 by the electronic governor 45, and performs sub-injection (post-injection) that injects fuel in the expansion stroke after the main injection of multistage injection. Can be done. This technique is described in, for example, Japanese Patent Application Laid-Open No. 2003-155915, Japanese Patent Application Laid-Open No. 2006-37925, Japanese Patent Application Laid-Open No. 2002-276340, and the like. Further, a fuel injection device for regeneration may be installed in the exhaust pipe 31 and the fuel injection for regeneration may be performed by operating this fuel injection device.

  In step S110, when regeneration of the filter 32a is started, a control signal (reproduction start signal) indicating that regeneration is started is output to the vehicle body control device 51 (step S120).

Next, it is determined whether combustion removal (regeneration) of PM accumulated on the filter 32a has been completed (step S130). As the amount of particulate matter (PM) collected by the filter 32a decreases, the differential pressure across the filter 32a decreases. In step S130 , a pressure value of the differential pressure before and after the filter that can be regarded as having been regenerated based on the experimental data is set as a regeneration end determination threshold, and the difference between the front and rear of the filter 32a indicated by the detection signal from the differential pressure detection device 33 is set. Whether or not the regeneration of the filter 32a is finished is determined based on whether or not the pressure falls below the threshold. In step S130, if it is determined that the combustion removal of the accumulated PM has not been completed, the process of step S130 is repeated. If it is determined that the combustion removal of the accumulated PM has been completed, it is for regeneration into the exhaust pipe 31. The fuel injection is stopped and the regeneration is finished (step S140). Further, immediately after the reproduction is finished, a control signal (reproduction end signal) indicating that the reproduction is finished is outputted (step S150).

  FIG. 5 is a flowchart showing an engine target speed calculation processing function including auto idle control of the vehicle body control device 51. The engine control system 4 includes the arithmetic processing function according to the flowchart of FIG. 5, the engine control dial 41, the mode switching device 42, the rotation speed detection device 43, the operation detection device 44, and the electronic governor 45.

  In FIG. 5, the vehicle body control device 51 determines whether or not the auto idle mode (specific mode) is selected based on the instruction signal from the mode switching device 42 (step S200), and the auto idle mode is selected. If it is determined that there is not, the target rotational speed of the engine 1 is set based on the instruction signal from the engine control dial 41, and a command signal for instructing the target rotational speed is output to the engine control device 52 (step S210). . If it is determined that the auto idle mode is selected, it is determined whether or not all the operation levers of the input operation device 25 (for example, the operation levers 27 and 28 shown in FIG. 3) are in a neutral state (step S220). If it is determined that all the levers are not in the neutral state, the process proceeds to step S210 described above, the target rotational speed of the engine 1 is set based on the instruction signal from the engine control dial 41, and the target rotational speed is instructed. Is output to the engine control device 52. When it is determined that all the operation levers are in the neutral state, the time after all the operation levers are in the neutral state is counted by a timer, and whether or not a predetermined time T1 set in advance has elapsed after the neutral state (neutral) Whether the time after the state has reached the predetermined time T1) is determined (step S240). If it is determined that the predetermined time T1 has not elapsed, the process proceeds to step S210, and an instruction from the engine control dial 41 is given. Based on the signal, a target rotational speed of engine 1 is set, and a command signal instructing the target rotational speed is output to engine control device 52. If it is determined in step S240 that the predetermined time T1 has elapsed after all the operating levers are in the neutral state, it is determined whether or not reproduction is currently being performed (step S250). This determination is performed based on the control signal (reproduction start signal) output in step S120 of FIG. 4 and the control signal (reproduction end signal) output in step S150. That is, in step S250, when a regeneration start signal is transmitted from the engine control device 52, it is determined that regeneration is in progress by setting the regeneration flag to ON, and when a regeneration end signal is transmitted from the engine control device 52. The reproduction flag is set to OFF and it is determined that reproduction is not in progress.

  If it is determined in step S250 that the engine is not currently being reproduced, the target rotational speed of the engine 1 is different from the rotational speed based on the instruction signal from the engine control dial 41, and is set to a predetermined low-speed rotational speed (for example, 1200 rpm). And a command signal for instructing the target rotational speed is output to the engine control device 52 (step S260). If it is determined that the engine is currently being reproduced, the process proceeds to step S210 described above, a target rotational speed of the engine 1 is set based on an instruction signal from the engine control dial 41, and a command signal for instructing the target rotational speed is issued. Output to the engine controller 52.

  When the engine control device 52 receives the target rotational speed command signal output in step S210 or S260 from the vehicle body control device 51, the engine control device 52 converts the target rotational speed and the detection signal (actual rotational speed) from the rotational speed detection device 43. Based on this, a fuel injection amount for maintaining the rotational speed of the engine 1 at the target rotational speed is calculated, and a fuel injection command is output to the electronic governor 45. Thereby, the rotation speed of the engine 1 is controlled to be maintained at the target rotation speed set in step S210 or S260 of FIG.

In the above, the processing function of the flowchart shown in FIG. 4 of the oxidation catalyst 32b, the differential pressure detection device 33, and the engine control device 52 is to burn and remove the particulate matter collected by the exhaust gas post-processing device 32 and to perform exhaust gas post-processing. The engine control dial 41 constitutes a rotation speed instruction means for instructing the rotation speed of the engine 1, and the operation detection device 44 is an operation for detecting the operation state of the work machine (hydraulic excavator). A state detection unit is configured, and the mode switching device 42 configures a mode switching unit. Further, the processing functions of steps S200, S220, S240, and S260 of the flowchart shown in FIG. 5 of the vehicle body control device 51 are performed when the mode switching means 42 selects a specific mode (auto idle mode). The first engine control means is configured to perform control for reducing the rotational speed of the engine 1 below the rotational speed instructed by the rotational speed instruction device 41 in accordance with the operating state and the end of the operation of the regeneration device . The processing functions of steps S250 and S210 in the flowchart shown in FIG. 5 detect whether or not the playback device is operating when the mode switching means 42 selects a specific mode (auto idle mode). When the engine is in operation, the engine is controlled so as to invalidate the control of the first engine control means and maintain the engine speed indicated by the engine speed indicating device 41. Constituting the second engine control means for controlling the rotational speed.
~ Operation ~
<Exhaust gas purification system 3>
When the amount of PM accumulated in the filter 32a of the exhaust gas aftertreatment device 32 increases and the differential pressure across the filter 32a detected by the differential pressure detection device 33 exceeds the regeneration start determination threshold, the engine control device 52 For example, by performing sub-injection (post-injection) for injecting fuel in the expansion stroke after the main injection of multistage injection, fuel for regeneration is injected into the exhaust pipe 31 and regeneration is started (step S100 in FIG. 4 → Step S110). Further, a control signal (reproduction start signal) indicating that reproduction is started simultaneously with the start of reproduction is output to the vehicle body control device 51 (step S120).

  As the exhaust gas temperature in the exhaust gas aftertreatment device 32 rises due to the fuel injection for regeneration and the combustion removal of the PM deposited on the filter 32a proceeds, the differential pressure across the filter 32a decreases. When the differential pressure across the filter 32a detected by the differential pressure detection device 33 falls below the regeneration end determination threshold, the engine control device 52 stops the fuel injection for regeneration into the exhaust pipe 31 and terminates the regeneration (step S130). → Step S140). Further, immediately after the reproduction is finished, a control signal (reproduction end signal) indicating that the reproduction is finished is outputted to the vehicle body control device 51 (step S150).

<Engine control system 4>
When the auto idle mode is selected and the operator operates the operation lever to perform excavation or the like, the vehicle body control device 51 sets the target rotational speed based on the instruction signal from the engine control dial 41. A command signal for instructing the target rotational speed is output to the engine control device 52 (step S200 → step S220 → step S210). The engine control device 52 controls the electronic governor 45 based on the command signal, and the rotational speed of the engine 1 is controlled to the rotational speed indicated by the engine control dial 41.

  Thereafter, when the operator returns the operation lever to neutral and the operation is interrupted or stopped, the vehicle body control device 51 passes a predetermined time T1 after all the operation levers are in the neutral state, and further from the engine control device 52. When the regeneration start signal is not transmitted (when the exhaust gas aftertreatment device 32 is not regenerating), the target rotational speed of the engine 1 is set to a predetermined low rotational speed (for example, 1200 rpm), and the target rotational speed is set. A command signal for instructing is output to the engine control device 52 (step S200 → step S220 → step S240 → step S250 → step S260). The engine control device 52 controls the electronic governor 45 based on the command signal, and the rotational speed of the engine 1 is controlled to a low speed (for example, 1200 rpm). Thereby, fuel consumption can be reduced and noise can be reduced.

  On the other hand, even when the predetermined time T1 has elapsed after all the operating levers are in the neutral state, when the regeneration start signal is transmitted from the engine control device 52 (the exhaust gas aftertreatment device 32 is regenerating). If there is, the vehicle body control device 51 sets a target rotational speed based on the instruction signal from the engine control dial 41, and outputs a command signal instructing the target rotational speed to the engine control device 52 (step S200 → step). S220 → step S240 → 250 → 210). The engine control device 52 controls the electronic governor 45 based on the command signal, and the rotational speed of the engine 1 is controlled to the rotational speed indicated by the engine control dial 41.

  Here, during the regeneration of the filter 32a of the exhaust gas after-treatment device 32, the internal temperature of the exhaust gas after-treatment device 32 rises to about 600 ° C. at which PM burns, so that a considerable amount is generated inside the exhaust gas after-treatment device 32. Heat is generated. Normally, this heat is cooled by the exhaust gas flowing, and the filter 32a is prevented from being damaged by the heat remaining inside the exhaust gas after-treatment device 32. However, if the engine speed is reduced by auto-idle control after the regeneration is started, the flow rate of the exhaust gas decreases, and accordingly the heat inside the exhaust gas aftertreatment device 32 does not escape and becomes an abnormally high temperature, The risk of damage to the filter 32a increases.

In the present embodiment, as described above, even when the predetermined time T1 has elapsed after all the operating levers are in the neutral state, the auto exhaust gas after-treatment device 32 is being regenerated. The engine 1 is controlled to the number of revolutions indicated by the engine control dial 41 without causing the idle control to function. Thereby, it is possible to prevent the filter 32a of the exhaust gas aftertreatment device 32 from being damaged due to a decrease in the engine speed due to auto idle control during regeneration.
~effect~
According to the present embodiment, since the operating speed of the engine 1 is reduced to a low speed after a predetermined time T1 has elapsed after all the operating levers are in a neutral state by auto idle control, fuel economy and noise are reduced. Can be reduced. Further, during regeneration, after all the control levers are in a neutral state, the engine speed does not decrease even after a predetermined time T1 has elapsed, so an exhaust gas aftertreatment device ( DPF) 32 can be prevented from being damaged.
<Second Embodiment>
A second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart similar to FIG. 5 showing the engine target speed calculation processing function including the auto idle control of the vehicle body control device in the present embodiment. The difference between the flowchart shown in FIG. 6 and the flowchart shown in FIG. 5 is that step S270 is added after step S250. The rest is the same as the flowchart shown in FIG.

  In the present embodiment, the vehicle body control device 51 determines that the predetermined time T1 has elapsed after the neutral state of all the operation levers in step S240, and in step S250, a regeneration start signal is transmitted from the engine control device 52. If it is determined that the exhaust gas aftertreatment device 32 is being regenerated, the process proceeds to step S210, where the target rotational speed of the engine 1 is set based on the instruction signal from the engine control dial 41, and the target rotational speed is indicated. A command signal is output to the engine control device 52. The steps so far are the same as those in the first embodiment. In this embodiment, after that, when a regeneration end signal is transmitted and it is determined that the reproduction is not being performed, the process immediately proceeds to step S260 and the target rotational speed of the engine 1 is preset at a low speed rotational speed (in the automatic idle control). For example, the time after the end of playback is counted by a timer, and the time after the end of playback (the time after transmission of the signal during playback has stopped) has passed a predetermined time T2. It is determined whether or not (whether the time after completion of reproduction has reached a predetermined time T2) (step S270). When it is determined that the predetermined time T2 has not elapsed since the end of regeneration (before the predetermined time T2 has elapsed since the end of regeneration), the process proceeds to step S210 and the target engine speed of the engine 1 is set. The rotation speed is maintained based on the instruction signal from the engine control dial 41, and when the time after the end of the reproduction has passed the predetermined time T2, the process proceeds to step S260 for the first time, and the target rotation speed of the engine 1 is set to a predetermined value. A low speed (for example, 1200 rpm) is set, and a command signal that indicates the target speed is output to the engine control device 52.

In the present embodiment configured as described above, even if it is determined that the reproduction is not being performed after the reproduction is completed, the rotation speed of the engine 1 is set to a low rotation speed (for example, 1200 rpm) until a predetermined time T2 after the reproduction ends. The engine speed is controlled to a rotational speed based on an instruction signal from the engine control dial 41 without decreasing. As a result, during the predetermined time T2 after the end of regeneration, the flow rate of exhaust gas is prevented from decreasing due to a decrease in engine speed, and a sufficient amount of exhaust gas flows, so that after exhaust gas is exhausted due to residual heat after completion of regeneration. It is possible to prevent the inside of the processing device 32 from becoming an abnormally high temperature and prevent the filter 32a from being damaged.
<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a flowchart similar to FIG. 5 showing the engine target speed calculation processing function including the auto idle control of the vehicle body control device in the present embodiment. The difference between the flowchart shown in FIG. 7 and the flowchart shown in FIG. 5 is that the process of step S270 is added after step S250 (same as the second embodiment), and the processes of steps S280 and S290 are further added. is there. The rest is the same as the flowchart shown in FIG.

  In the present embodiment, the vehicle body control device 51 transmits a regeneration start signal from the engine control device 52 in step S250 and determines that the exhaust gas aftertreatment device 32 is regenerating, and regenerates in step S270. If it is determined that the predetermined time T2 has not elapsed after the end (before the time after reproduction has elapsed the predetermined time T2), there is an instruction to further reduce the rotational speed from the engine control dial 41, It is determined whether the rotational speed based on the instruction signal from the engine control dial 41 is equal to or less than a predetermined rotational speed NZ set in advance (step S280), and the rotational speed based on the instruction signal from the engine control dial 41 is the predetermined rotational speed. If the number is not less than NZ, the process proceeds to step S210 and an instruction from the engine control dial 41 is given. It sets a target rotational speed of the engine 1 based on the item, and outputs a command signal for instructing the target revolution speed to the engine control unit 52. If it is determined in step S280 that the rotational speed based on the instruction signal from the engine control dial 41 is equal to or lower than the predetermined rotational speed NZ, the predetermined rotational speed NZ is set as the target rotational speed of the engine 1, and the target A command signal for instructing the rotational speed is output to the engine control device 52 (step S290). Here, the predetermined rotational speed NZ is an engine rotational speed (that is, an exhaust gas flow rate sufficient to cool the filter 32 during regeneration of the filter 32a of the exhaust gas after-treatment device 32 (PM combustion) (that is, an engine rotational speed). , Engine speed suitable for regeneration), for example, 1800 rpm.

In the present embodiment configured as described above, the operator inadvertently operates the engine control dial 41 during the reproduction and before the lapse of the predetermined time T2 after the reproduction ends, and the rotation speed based on the instruction signal is greatly reduced. However, the engine speed does not decrease below the predetermined speed, and the engine speed is controlled to the predetermined speed. As a result, the exhaust gas flow rate is prevented from decreasing due to a decrease in the engine speed, and the exhaust gas post-treatment device due to the heat trapped inside the exhaust gas post-treatment device 32 when a sufficient flow rate of exhaust gas flows. The inside of 32 can be prevented from becoming an abnormally high temperature, and damage to the filter 32a can be prevented.
<Fourth embodiment>
A fourth embodiment of the present invention will be described with reference to FIGS.

  FIG. 8 is a diagram showing an overall system configuration of a working machine provided with an engine control system and an exhaust gas purification system in a fourth embodiment of the present invention. This embodiment is also a case where the present invention is applied to a hydraulic excavator which is a typical example of a construction machine.

  In FIG. 8, the hydraulic system 2 </ b> A in the present embodiment is based on the discharge pressure of the hydraulic pump 21 so that the absorption torque (consumption torque) of the hydraulic pump 21 does not exceed the maximum absorption torque that is a predetermined value. A torque control regulator 61 that controls the tilt of the pump 21 (the amount of tilt of the swash plate; the displacement or capacity) is provided.

  The engine control system 4A includes a mode switching device 42A that selects the economy mode instead of the mode switching device 42 that selects the auto idle mode in the first embodiment, and newly detects the discharge pressure of the hydraulic pump 21. A pressure detection device 62 (operating state detection means) is provided.

  FIG. 9 is a diagram showing details of the torque control regulator 61. The torque control regulator 61 includes a control spool 63s operatively connected to the displacement displacement mechanism 21a of the hydraulic pump 21, springs 63a and 63b acting on the control spool 63s in the capacity increasing direction of the hydraulic pump 21, and a control spool. A tilt control actuator 63 provided with pressure receiving portions 63c and 63d acting in the direction of capacity reduction of the hydraulic pump 21 with respect to 63s and an electromagnetic proportional valve 64 are provided. The discharge pressure of the hydraulic pump 21 is introduced to the pressure receiving portion 63c of the actuator 63 via the pilot line 65, and the control pressure output from the electromagnetic proportional valve 64 is introduced to the pressure receiving portion 63d via the control oil path 66. . The electromagnetic proportional valve 64 generates a control pressure corresponding to the drive signal from the vehicle body control device 51A using the discharge pressure of the pilot pump 22 as a source pressure. The springs 63a and 63b and the pressure receiving portion 63d function as means for setting the maximum absorption torque that can be used by the hydraulic pump 21. With such a configuration, the regulator 61 has the maximum absorption torque of the hydraulic pump 21 set by the difference between the urging force of the springs 63a and 63b and the oil pressure generated by the control pressure from the electromagnetic proportional valve 64 in the pressure receiving portion 63d. The capacity of the hydraulic pump 21 is controlled so as not to exceed the absorption torque. The maximum absorption torque can be adjusted by operating the electromagnetic proportional valve 64 with a drive signal from the vehicle body control device 51A and changing the control pressure output by the electromagnetic proportional valve 64.

FIG. 10 is a diagram illustrating the torque control characteristics of the regulator 61. The horizontal axis is the discharge pressure of the hydraulic pump 21, and the vertical axis is the tilt (displacement volume or capacity) of the hydraulic pump 21. A1, A2 and A3 are maximum absorption torque characteristic lines set by the difference between the urging forces of the springs 63a and 63b and the oil pressure of the pressure receiving chamber 63d. As the control pressure output from the electromagnetic proportional valve 64 increases (the drive current increases), the characteristic line of the maximum absorption torque set by the difference between the urging forces of the springs 63a and 63b and the oil pressure of the pressure receiving chamber 63d is It changes to A1, A2, A3, and the maximum absorption torque of the hydraulic pump 21 decreases to TR1, TR2, TR3. X is a torque control region of the torque control regulator 61 when the torque control characteristic of the regulator 61 is set to the characteristic line A1, and Y is a region where the pressure is lower than the torque control region X. PdA is the lowest pressure in region X and is the torque control start pressure. Maximum characteristic line of the absorption torque is set to A1 Rutoki, the regulator 61, when the delivery pressure of the hydraulic pump 21 is in the lower region Y than PdA keeps the tilting of the hydraulic pump 21 to the maximum qmax, the hydraulic pump When the discharge pressure of the hydraulic pump 21 is in the region X equal to or higher than PdA, the tilt of the hydraulic pump 21 is controlled to decrease along the characteristic line A1 as the discharge pressure of the hydraulic pump 21 increases. The absorption torque (consumption torque) is controlled so as not to exceed the maximum absorption torque TR1 corresponding to the characteristic line A1. Rutoki maximum absorption torque characteristic line is set to A2, A3 are also the same.

Figure 11 is a diagram showing a calculation processing function of the maximum absorption torque of the vehicle body controller 51A.

  In FIG. 11, the vehicle body control device 51 </ b> A has processing functions of a pump maximum absorption torque calculation unit 71, an electromagnetic proportional valve output pressure calculation unit 72, and an output current calculation unit 73.

  The pump maximum absorption torque calculating unit 71 inputs a signal of a target engine speed NR1 (described later), refers to this in a table stored in the memory, and the hydraulic pump 21 according to the target engine speed NR1 at that time. The maximum absorption torque TR is calculated. This maximum absorption torque TR is a target maximum absorption torque of the hydraulic pump 21 that matches the output torque characteristics of the engine 1 rotating at the target engine speed NR1, and the target engine speed NR1 is the maximum in the memory table. When the engine speed is at the rated speed Nmax, the maximum absorption torque TR is the largest and the maximum rated speed TRmax. As the target engine speed NR1 decreases from the maximum rated speed TRmax, the maximum absorption torque TR decreases, and the target engine The relationship between NR1 and TR is set so that the maximum absorption torque TR is also minimized when the rotational speed NR1 is in a low rotational speed region near the idle rotational speed.

  The output pressure calculator 72 receives the maximum absorption torque TR, and the output pressure of the electromagnetic proportional valve 64 at which the maximum absorption torque set by the difference between the urging force of the springs 63a and 63b and the oil pressure of the pressure receiving chamber 63d becomes TR. (Control pressure) SP is obtained, and the output current calculation unit 73 obtains the drive current SI of the electromagnetic proportional valve 64 from which the output pressure (control pressure) SP is obtained, and outputs this to the electromagnetic proportional valve 64.

Proportional solenoid valve 64 which inputs driving current SI outputs the control pressure SP corresponding to the driving current S I, the actuator 63 of the torque control regulator 61 according to the target engine revolution speed NR1 calculated in the pump maximum absorption torque calculation unit 71 Set the maximum absorption torque TR.

  In FIG. 10, the characteristic line A1 of the maximum absorption torque is obtained when the target engine speed NR1 is at the maximum rated speed Nmax, and TR1 = TRmax. The large absorption torque TR calculated by the pump maximum absorption torque calculation unit 71 decreases as the target engine speed NR1 decreases from the maximum rated speed TRmax, and therefore the maximum absorption set in the actuator 63 of the torque control regulator 61. The torque characteristic line also changes to A2 and A3. That is, a maximum absorption torque that decreases as the target engine speed NR1 decreases is set in the torque control regulator 61.

  FIG. 12 is a flowchart similar to FIG. 5 showing the engine target speed calculation processing function including the economy mode control of the vehicle body control device 51A. The engine control system 4A is configured by the arithmetic processing function according to the flowchart of FIG. 12, the engine control dial 41, the mode switching device 42A, the rotation speed detection device 43, the operation detection device 44, the electronic governor 45, and the pressure detection device 62. .

  The conventional general economy mode is a mode in which the engine speed is reduced by a certain amount from the maximum rated speed Nmax regardless of the operation state of the vehicle body, whereas the economy mode according to the present invention is a discharge mode of the hydraulic pump. In this mode, the engine speed is decreased according to the pressure, and the economy mode according to the present invention is referred to as a new economy mode in order to distinguish it from the conventional general economy mode.

In FIG. 12, the vehicle body control device 51A determines whether the new economy mode is selected based on the instruction signal from the mode switching device 42A (step S300), and it is determined that the new economy mode is not selected. In this case, the target rotational speed of the engine 1 is set based on the instruction signal from the engine control dial 41, and a command signal for instructing the target rotational speed is output to the engine control device 52 (step S310). If it is determined in step S300 that the new economy mode is selected, it is next determined whether or not the work currently performed by the hydraulic excavator (construction machine) is a light load work (step S320). The determination as to whether or not the work is a light load is performed, for example, using the detection signal of the pressure detection device 62 that detects the discharge pressure of the hydraulic pump 21 (hereinafter referred to as Pd) as follows.

・ Pd <PdB → Light load work ・ Other than above (Pd ≧ PdB) → Not light load work
PdB: Pump discharge pressure judgment value for light load work

Both the detection signal of the pressure detection device 62 that detects the discharge pressure Pd of the hydraulic pump 21 and the detection signal of the pressure detection device 44g (operation detection device 44) that detects the control pilot pressure (hereinafter referred to as Pi) of the remote control valve. May be used as follows.

・ Pd <PdB and Pi <Pia → light load operation ・ Other than above (Pd <PdB and Pi ≧ Pia or Pd ≧ PdB → not light load operation)
PdB: Pump discharge pressure judgment value for determining whether or not the work is light load (described later)
Pia: Control pilot pressure judgment value for light load work

The pump discharge pressure determination value PdB is a pressure near the middle of the discharge pressure change range of the hydraulic pump 21, and is equal to, for example, the lowest pressure (starting pressure of torque control) PdA in the torque control region X of the torque control regulator 61, or It is set to a nearby value (PdB = PdA or PdB≈PdA). The control pilot pressure determination value Pia is a control pilot pressure corresponding to the maximum operation amount of the operation lever device in a fine operation operation (for example, a horizontal pulling operation for leveling the surface of earth and sand).

  If it is determined in step S320 that the work currently being performed is a light load work, the process proceeds to step S310, where the target rotational speed of the engine 1 is set based on the instruction signal from the engine control dial 41, and the target rotational speed is set. Is output to the engine control device 52. If it is determined in step S320 that the work currently being performed is not a light load work, it is next determined whether or not the work is currently being reproduced (step S330). In other words, when a reproduction start signal is transmitted from the engine control device 52, it is determined that reproduction is in progress by setting the reproduction flag to ON. When a reproduction end signal is transmitted from the engine control device 52, the reproduction flag is set. Set to OFF and determine that playback is not in progress.

  If it is determined in step S330 that the engine is not currently being regenerated, the target rotational speed of the engine 1 is different from the rotational speed based on the instruction signal from the engine control dial 41, and decreases as the discharge pressure of the hydraulic pump 21 increases. A low-speed rotational speed (described later) is set, and a command signal for instructing the target rotational speed is output to the engine control device 52 (step S340). If it is determined in step S330 that the reproduction is currently being performed, the process proceeds to step S310, where the target rotational speed of the engine 1 is set based on an instruction signal from the engine control dial 41, and the target rotational speed is instructed. The signal is output to the engine control device 52.

Similarly to the first embodiment, when the engine control device 52 receives the target rotational speed command signal output from the vehicle body control device 51A in step S310 or S340, the engine control device 52 outputs the target rotational speed and the rotational speed detection device 43. The electronic governor 45 is controlled based on the detection signal (actual rotational speed), and the rotational speed of the engine 1 is controlled so that the target rotational speed set in step S310 or S340 is maintained.

  FIG. 13 is a block diagram showing the engine set speed calculation processing function of the vehicle body control device 51A shown in the flowchart of FIG.

  In FIG. 13, the vehicle body control device 51A includes a reference target rotational speed calculation unit 400a, a power mode rated target rotational setting unit 400b, an engine rotational speed correction value calculation unit 400d, a work mode selection unit 400e, a regenerating E mode release unit 400x, Each function of the subtraction unit 400f and the minimum value selection unit 400g is provided.

  The reference target rotational speed calculation unit 400a inputs the signal of the operation angle α of the engine control dial 41, refers to the table stored in the memory, and refers to the reference target rotational speed NRO according to the operation angle α at that time. Is calculated. This NRO is a reference value for the target engine speed NR1, and the relationship between α and NRO is set so that the reference target speed NRO increases as the operating angle α increases.

  The power mode rated target rotation setting unit 400b is set with the maximum rated speed Nmax of the power mode, and outputs this Nmax.

Engine speed correction value calculation unit 400d receives the discharge pressure Pd of the hydraulic pump 21 detected by the pressure detector 62, and refers to a table stored in a memory, corresponding to the discharge pressure Pd at that time An engine speed correction value ΔN0 is calculated.

  FIG. 14 shows an enlarged view of the relationship between the pump discharge pressure Pd and the engine speed correction value ΔN0 in the engine speed correction value calculation unit 400d. In the memory table, when the pump discharge pressure Pd is lower than the pressure PdB, which is a pump discharge pressure determination value as to whether or not the work is a light load, the engine speed correction value ΔN0 is 0, and the pump discharge pressure Pd is equal to or higher than the pressure PdB. The relationship between Pd and ΔN0 is set so that the engine speed correction value ΔN0 increases as the pump discharge pressure Pd increases.

When work mode selection unit 400e, when the mode switching device 42A has selected the standard mode is off, this time to output the engine revolution speed modification value .DELTA.N1 = 0, mode switching device 42A has selected the Economy over mode Is turned on, and at this time, the engine speed correction value ΔN0 calculated by the engine speed correction value calculation unit 400d is output.

  The during-reproduction E mode canceling unit 400x is on when the during-reproduction flag is set to OFF (when not during reproduction), and at this time, outputs the engine speed correction value ΔN1 and the during-regeneration flag is turned on. When it is set (during reproduction), it is turned off, and at this time, the engine speed correction value ΔN1 = 0 is output.

  The subtracting section 400f subtracts the engine correction rotational speed ΔN0 that is the output of the regenerating E mode canceling section 400x from the maximum rated rotational speed Nmax output from the rated target rotational setting section 400b, and calculates the target engine rotational speed NR2. (NR2 = Nmax-.DELTA.N0). Here, for example, when Nmax is 1900 rpm, the maximum value ΔN0max of the engine correction rotational speed ΔN0 is 300 rpm, and the minimum value NR2min of the target engine rotational speed NR2 is 1600 rpm.

  The minimum value selection unit 400g selects a smaller one of the reference target rotation speed NRO calculated by the reference target rotation speed calculation unit 400a and the target rotation speed NR2 calculated by the subtraction unit 400f, and sets this as the target engine speed NR1. Output. This target engine speed NR1 is output to the engine control device 52 as a command signal.

  The function of the work mode selection unit 400e corresponds to the process of step S300 in FIG. 12, the function of the reference target speed calculation unit 400a corresponds to the process of step S310 in FIG. 12, and the function of the engine speed correction value calculation unit 400d. Corresponds to the process of step S320 in FIG. 12, and the function of the E-mode release unit 400x during playback corresponds to the process of step S330 in FIG. 12, and includes a power mode rated target rotation setting unit 400b and an engine speed correction value calculation unit 400d. The functions of the subtraction unit 400f and the minimum value selection unit 400g correspond to the processing in step S340 in FIG.

In the above, the pressure detection device 62 (or the operation detection device 44 and the pressure detection device 62) constitutes an operation state detection means for detecting the operation state of the work machine (hydraulic excavator), and the mode switching device 42A constitutes a mode switching means. To do. Further, steps in the flowchart shown in FIG. 12 of the vehicle body controller 51A S300, S320, S340 processing functions when the mode switching means 42A has selected a specific mode (economy mode), and the operating state of the working machine FIG. 12 is a flowchart of the vehicle body control device 51A that constitutes a first engine control means that performs control to lower the rotational speed of the engine 1 below the rotational speed instructed by the rotational speed instruction device 41 in response to the end of the operation of the regeneration device . The processing functions of steps S330 and S310 detect whether or not the playback device is operating when the mode switching means 42A selects a specific mode (economy mode), and the playback device is operating. In such a case, the control of the first engine control means is invalidated and the engine 1 is rotated so as to maintain the rotational speed indicated by the rotational speed indicating device 41. Constituting the second engine control means for controlling the number.

  FIG. 15 shows the pump discharge pressure in the new economy mode when the maximum rated speed Nmax is set by the engine control dial 41 (when the maximum rated speed Nmax is calculated by the reference target speed calculating unit 400a). It is a figure which shows the change of the target engine speed NR1, The solid line E and F1 are things when it is not reproducing | regenerating, The solid line E and the dashed-dotted line F2 are things when it is reproducing | regenerating. When the pump discharge pressure Pd is equal to or lower than the pressure PdB (during light load operation), the engine correction rotational speed ΔN0 = 0, and the target engine rotational speed NR1 is the maximum rating regardless of whether the engine is being regenerated as indicated by the solid line E. The rotational speed is Nmax. When the pump discharge pressure Pd is higher than the pressure PdB when the pump discharge pressure Pd is higher than the pressure PdB, the engine correction rotation speed ΔN0 increases as the pump discharge pressure Pd increases, and the engine correction rotation speed ΔN0 is subtracted from the maximum rated rotation speed Nmax. Becomes the target engine speed NR1, and as indicated by the solid line F1, the target engine speed NR1 gradually decreases from the maximum rated speed Nmax as the pump discharge pressure Pd increases. On the other hand, since the engine correction rotational speed ΔN0 is not output during the regeneration, the target engine rotational speed NR1 does not change and remains at the maximum rated rotational speed Nmax, as indicated by the alternate long and short dash line F2.

  FIG. 16 shows a hydraulic pump when the mode switching device 42A is switched from the standard mode to the new economy mode when the maximum rated speed Nmax is set with the engine control dial 41 in the engine control system 4A according to the present embodiment. It is a figure which shows the relationship between 21 discharge pressure and discharge flow volume. In the figure, solid lines A and B1 show the relationship between the discharge pressure and discharge flow rate of the hydraulic pump 21 in the standard mode, and the solid line A and dotted line B2 show the discharge pressure of the hydraulic pump 21 when in the new economy mode and not being regenerated. The relationship with the discharge flow rate is shown. Z is a reduction amount of the pump discharge flow rate corresponding to the reduction amount of the maximum absorption torque (maximum absorption torque set in the torque control regulator 61) which is reduced in accordance with the reduction of the engine speed calculated by NR2 = Nmax−ΔN0. It is a characteristic line shown. An alternate long and short dash line C indicates a change in pump discharge flow rate in a conventional general economy mode for comparison.

  In the conventional general economy mode, the engine speed is lowered from the maximum rated speed Nmax by a certain amount regardless of the operation state of the vehicle body. Therefore, as indicated by a dashed line C, the pump discharge flow rate is also in the standard mode in the region Y. The torque is decreased by a certain amount from the discharge flow rate, and in the torque control region X, the amount is decreased by a certain amount corresponding to the amount of decrease in the maximum absorption torque (a certain amount).

  On the other hand, in the new economy mode according to the present invention, when the discharge pressure of the hydraulic pump 21 is lower than the pressure PdB (torque control start pressure), the engine correction rotational speed ΔN0 = 0, and the engine rotational speed is the maximum rating. Since the rotational speed Nmax remains unchanged, as indicated by the solid line A, the pump discharge flow rate does not decrease in the region Y and is the same as that in the standard mode. When the discharge pressure of the hydraulic pump 21 becomes higher than the pressure PdB when not being regenerated, the engine speed gradually increases from the maximum rated speed Nmax by the engine correction speed ΔN0 as the discharge pressure of the hydraulic pump 21 increases. Accordingly, the maximum absorption torque set in the torque control regulator 61 gradually decreases accordingly, so that the amount of decrease in the discharge flow rate of the hydraulic pump 21 increases as indicated by the characteristic line Z. As a result, the hydraulic pump As shown by the broken line B2, the discharge flow rate 21 is smaller than the discharge flow rate in the standard mode. The amount of decrease increases as the discharge pressure of the hydraulic pump 21 increases.

  FIG. 17 is a diagram illustrating the pump load frequency. Normally, various load states are continuously mixed in a series of operations, and the pump load frequency is as shown in FIG. The pump load pressure on the horizontal axis corresponds to the pump discharge pressure. FIG. 18 is a diagram in which a region with high pump frequency is superimposed on the pump discharge amount characteristic diagram. The region where the pump load frequency is high corresponds to the intermediate pump discharge pressure range.

  In the present embodiment, in the new economy mode according to the present invention, the engine rotation is controlled to be low in a range where the pump discharge pressure (load) is high, which is effective in improving fuel efficiency. In the range where the pump discharge pressure (load) is low. Work is possible at the same flow rate (working speed) as in the standard mode. Further, in the middle load region where the load frequency is high, it is possible to perform rotation speed control that can achieve both fuel efficiency and work speed. As a result, the engine speed can be reduced and fuel efficiency can be improved in areas with high loads, and work efficiency can be reduced by reducing performance degradation (decrease in work speed) due to a decrease in pump discharge flow in the required load areas. Can be improved. In addition, even if the load frequency changes during work, the motor speed continuously changes, so it is possible to prevent a sudden change in work speed and a sense of incongruity in operation due to fluctuations in engine sound, which improves operability. it can.

Further, in the present embodiment, since the engine correction rotational speed ΔN0 is not output during the regeneration, the target engine rotational speed NR1 does not change and the maximum rated rotational speed is shown as indicated by the one-dot chain line F2 in FIG. The number Nmax remains. As a result, it is possible to prevent the filter 32a of the exhaust gas aftertreatment device 32 from being damaged due to a decrease in engine speed due to control in the new economy mode during regeneration.
<Fifth embodiment>
A fifth embodiment of the present invention will be described with reference to FIG. FIG. 19 is a flowchart similar to FIG. 12 showing the engine target speed calculation processing function including the economy mode control of the vehicle body control device in the present embodiment. In the present embodiment, the engine target rotational speed calculation processing function including the economy mode control in the fourth embodiment is modified in the same manner as in the second embodiment in FIG.

  That is, in the present embodiment, vehicle body control device 51A determines in step S300 that the new economy mode is selected, and in step S320, determines that the current work is not a light load work, and in step S330. If it is determined that the exhaust gas aftertreatment device 32 is currently being regenerated, the process proceeds to step S310, where the target rotational speed of the engine 1 is set based on the instruction signal from the engine control dial 41, and the target rotational speed is set. Is output to the engine control device 52. The steps so far are the same as those in the fourth embodiment. In this embodiment, after that, when a regeneration end signal is transmitted from the engine control device 52 in step S330 and it is determined that regeneration is not in progress, the routine immediately proceeds to step S340, where the target rotational speed of the engine 1 is set to the hydraulic pump. Instead of setting to a low-speed rotation speed that decreases as the discharge pressure increases, the time after completion of reproduction is counted by a timer, and the time after completion of reproduction (after transmission of the signal being reproduced is stopped) It is determined whether or not (predetermined time) has passed a predetermined time T2 (whether the time after completion of reproduction has reached the predetermined time T2) (step S350). When it is determined that the time after the end of regeneration has not passed the predetermined time T2 (before the time after the end of regeneration has passed the predetermined time T2), the process proceeds to step S310, and the target rotational speed of the engine 1 is set. The engine speed is maintained at the speed based on the instruction signal from the engine control dial 41, and when the time after the end of the regeneration has passed the predetermined time T2, the process proceeds to step S340 for the first time, and the target speed of the engine 1 is discharged from the hydraulic pump 21. A low speed rotational speed that decreases as the pressure increases is set, and a command signal that indicates the target rotational speed is output to the engine control device 52.

Even in the present embodiment configured as described above, the new economy mode control is adopted as the engine speed reduction control, and the same effect as in the second embodiment (prevention of damage to the filter 32a due to residual heat after regeneration is completed) Effect).
<Sixth Embodiment>
A sixth embodiment of the present invention will be described with reference to FIG. FIG. 20 is a flowchart similar to FIG. 12 showing the engine target speed calculation processing function including the economy mode control of the vehicle body control device in the present embodiment. The difference between the flowchart shown in FIG. 20 and the flowchart shown in FIG. 12 is that step S350 is added after step S330 (same as the fifth embodiment), and steps S360 and S370 are added. is there. The rest is the same as the flowchart shown in FIG.

In the present embodiment, the vehicle body control device 51 transmits a regeneration start signal from the engine control device 52 in step S330 and determines that the exhaust gas aftertreatment device 32 is regenerating, and regenerates in step S350. If it is determined that the predetermined time T2 has not elapsed after the end (before the time after reproduction has elapsed the predetermined time T2), there is an instruction to further reduce the rotational speed from the engine control dial 41, It is determined whether the rotational speed based on the instruction signal from the engine control dial 41 is equal to or lower than a predetermined rotational speed NZ (for example, 1800 rpm) (step S360), and the rotational speed based on the instruction signal from the engine control dial 41 is determined. If the engine speed is not equal to or less than the predetermined rotational speed NZ, the process proceeds to step S310 and the engine controller It sets a target rotational speed of the engine 1 based on the instruction signal from the dial 41, and outputs a command signal for instructing the target revolution speed to the engine control unit 52. If it is determined in step S360 that the rotational speed based on the instruction signal from the engine control dial 41 is equal to or lower than the predetermined rotational speed NZ, the predetermined rotational speed NZ is set as the target rotational speed of the engine 1, and and it outputs an instruction signal for Shimegikai number rolling to the engine control unit 52 (step S370).

  Also in the present embodiment configured as described above, when the new economy mode control is adopted as the engine speed reduction control, the same effect as in the second embodiment (a predetermined time T2 elapses during and after the regeneration ends). An effect of preventing the filter 32a from being damaged when the operator inadvertently operates the engine control dial 41 before and the rotational speed based on the instruction signal is greatly reduced is obtained.

  The above embodiment can be variously modified within the spirit of the present invention. For example, in the above embodiment, auto idle control (first to third embodiments) is used as engine control for reducing the engine speed to be lower than the engine speed indicated by the engine speed instruction device in accordance with the operating state of the work implement. Alternatively, although the present invention is applied to the new economy mode control (fourth to sixth embodiments), there is a possibility that the filter 32a of the exhaust gas aftertreatment device 32 is damaged due to a decrease in the engine speed during regeneration. The present invention may be applied to other engine control as long as the engine control is performed. In this case, the same effect can be obtained.

It is a figure which shows the whole system of the working machine containing the engine control system and exhaust gas purification system in the 1st Embodiment of this invention. It is a figure which shows the detail of the hydraulic system and operation detection apparatus which are shown in FIG. It is a figure which shows the external appearance of the hydraulic excavator (work machine) provided with the system shown in FIG. It is a flowchart which shows the filter regeneration calculation process of an engine control apparatus. It is a flowchart which shows the auto idle control calculation process of a vehicle body control apparatus. FIG. 6 is a flowchart similar to FIG. 5, showing an auto idle control calculation process of the vehicle body control device in the second embodiment of the present invention. It is a flowchart similar to FIG.5 and FIG.6 which shows the auto idle control arithmetic processing of the vehicle body control apparatus in the 3rd Embodiment of this invention. It is a figure which shows the whole system of the working machine containing the engine control system and exhaust gas purification system in the 4th Embodiment of this invention. It is a figure which shows the detail of a torque control regulator. It is a figure which shows the torque control characteristic of a torque control regulator. It is a figure which shows the arithmetic function of the maximum absorption torque of a vehicle body control apparatus. FIG. 6 is a flowchart similar to FIG. 5 showing an engine target speed calculation processing function including economy mode control of the vehicle body control device. It is a figure which shows the engine setting rotation speed calculation processing function of the vehicle body control apparatus shown by the flowchart in FIG. It is a figure which expands and shows the relationship between the pump discharge pressure in an engine speed correction value calculating part, and an engine speed correction value. It is a figure which shows the change of the target engine speed with respect to the pump discharge pressure in the new economy mode when the maximum rated speed is set with the engine control dial. In the engine control system according to the fourth embodiment, the discharge pressure and the discharge flow rate of the hydraulic pump when the mode switching device is switched from the standard mode to the new economy mode when the maximum rated speed is set with the engine control dial. It is a figure which shows the relationship. It is a figure which shows pump load frequency. It is a figure which overlaps and shows the area | region where pump frequency is high on a pump discharge amount characteristic view. FIG. 13 is a flowchart similar to FIG. 12 showing an engine target speed calculation processing function including economy mode control of a vehicle body control device in a fifth embodiment of the present invention. FIG. 13 is a flowchart similar to FIG. 12 showing an engine target speed calculation processing function including economy mode control of a vehicle body control device in a sixth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 , 2A hydraulic system 3 Exhaust gas purification system 4 , 4A engine control system 21 Hydraulic pump
21a Variable displacement mechanism 22 Pilot pump 23 Actuator group
23a Hydraulic motor
23b, 23c Hydraulic cylinder
24a~24c flow control valve 24 control valve apparatus 25 an input operation equipment
25a-25c remote control valve
26 Pilot relief valve
27, 28 Operation lever
29a to 24f Pilot line 31 Exhaust pipe 32 Exhaust gas aftertreatment device (DPF)
32a Filter 32b Oxidation catalyst 33 Differential pressure detection device 41 Engine control dial 42, 42A Mode switching device 43 Rotational speed detection device 44 Operation detection device
44a-44f Shuttle valve
44g Pressure detection device 45 Electronic governor 51, 51A Car body control device 52 Engine control device 61 Torque control regulator 62 Pressure detection device 63 Actuator 63s Control spool 63a, 63b Spring 63c, 63d Pressure receiving portion 64 Electromagnetic proportional valve 65 Pilot line
66 Control oil passage
71 Pump maximum absorption torque calculator
72 Output pressure calculator
73 Output current calculator
100 Lower traveling body
101 Upper swing body
102 Front work machine
103a, 103b Crawler type traveling device
104a, 104b Traveling motor
105 slewing motor
106 engine room
107 cabin (cab)
111 boom
112 arms
113 buckets
114 Boom cylinder
115 Arm cylinder
116 Bucket cylinder 400a Reference target rotation speed calculation section 400b Power mode rated target rotation setting section 400d Engine rotation speed correction value calculation section 400e Work mode selection section 400f Subtraction section 400g Minimum value selection section 400x Reproducing E mode release section

Claims (6)

An engine, a hydraulic drive device including a hydraulic pump driven by the engine, an exhaust gas aftertreatment device that is attached to the exhaust system of the engine and collects particulate matter contained in the exhaust gas; in working machine the engine control system that includes a reproduction apparatus the collected particulate matter in the processor combustion removed to regenerate the exhaust gas after-treatment device,
A rotation speed instruction means for instructing the rotation speed of the engine;
Operating state detecting means for detecting the operating state of the work implement;
Mode switching means;
When the mode switching means selects a specific mode, the engine speed instruction device indicates the engine speed in accordance with the operating state of the work implement and the end of operation of the regeneration device that is in operation. First engine control means for performing control to reduce the rotational speed to be reduced;
When the mode switching means selects a specific mode, it is detected whether or not the regeneration device is in operation. When the regeneration device is in operation, the control of the first engine control means is invalidated. And a second engine control means for controlling the engine speed so as to maintain the engine speed indicated by the engine speed instruction device. The engine control system for a work machine according to claim 1,
The hydraulic drive device includes a plurality of actuators driven by pressure oil from the hydraulic pump, a control valve device that controls the flow of pressure oil supplied from the hydraulic pump to the plurality of actuators, and the control valve device An input operation device that controls the drive of the plurality of actuators by operating
The operation state detection means has an operation detection device that detects the presence or absence of operation of the input operation device as the operation state of the work implement,
The first engine control means detects the presence of an operation of the input operation device when the mode switching means selects the specific mode, and detects the engine in response to an instruction from the rotation speed instruction device. The number of revolutions that controls the number of revolutions , and that the number of revolutions of the engine indicates the number of revolutions of the engine when it is detected that the input operation device is not operated and the end of the operation of the playback device is detected. Control to lower,
The second engine control means, when the mode switching means is selecting a specific mode, when the playback device is operating, even when no operation of the input operation device is detected, An engine control system for a working machine, wherein the engine speed is controlled in accordance with an instruction from a rotation speed instruction device. The engine control system for a work machine according to claim 1,
The hydraulic drive device includes a plurality of actuators driven by pressure oil from the hydraulic pump, a control valve device that controls the flow of pressure oil supplied from the hydraulic pump to the plurality of actuators, and the control valve device. Based on the input operation device that controls the driving of the plurality of actuators and the discharge pressure of the hydraulic pump, the absorption torque of the hydraulic pump is set to a maximum absorption torque that is set depending on the engine speed. A torque control regulator for controlling the capacity of the hydraulic pump so as not to exceed,
The operating state detecting means has a pressure detecting device that detects a discharge pressure of the hydraulic pump as an operating state of the working machine,
The first engine control means, when the mode switching means is selecting the specific mode, when the discharge pressure of the hydraulic pump detected by the pressure detection device is lower than a predetermined pressure, the rotational speed of the engine is controlled in accordance with the instructions of the apparatus, the discharge pressure of the hydraulic pump is detected by the pressure detecting device Ri Do than the predetermined pressure, and operation completion of the reproduction apparatus is in operation is When detected Ru, it performs control to lower than the rotational speed of the rotational speed of the engine is the rotational speed instruction device instructs,
The second engine control means is configured such that when the mode switching means selects a specific mode and the regeneration device is operating, the discharge pressure of the hydraulic pump detected by the pressure detection device is An engine control system for a working machine that controls the rotation speed of the engine in accordance with an instruction from the rotation speed instruction device even when the pressure is equal to or higher than the predetermined pressure. In the engine control system of the working machine according to any one of claims 1 to 3,
The second engine control means controls the engine speed in accordance with an instruction from the engine speed instruction device until a predetermined time elapses after the operation of the regeneration device is completed. Engine control system. In the engine control system of the working machine according to any one of claims 1 to 3,
The second engine control means, when the regeneration device is in operation, sets the engine speed when the engine speed indicated by the speed indicator decreases below a predetermined speed. An engine control system for a working machine, characterized in that control is performed so as to maintain the rotation speed. In the engine control system of the working machine according to any one of claims 1 to 3,
The second engine control means is configured such that the engine speed indicated by the rotation speed instruction device is a predetermined rotation speed when the regeneration apparatus is in operation and until a predetermined time elapses after the operation of the regeneration apparatus ends. An engine control system for a working machine that controls to maintain the engine speed at the predetermined speed when the engine speed decreases below.

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