JP2010007562A - Exhaust emission control system of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control system capable of preventing engine oil from exerting poor lubricating performance resulting from fuel dilution during reproduction control and also preventing fuel economy from being deteriorated due to reproduction control. <P>SOLUTION: Each time the reproduction of a DPF (Diesel Particulate Filter) 42 is finished, the number of reproduction times N is counted, and a fuel dilution amount D is calculated on the basis of the number of reproduction times N. When the fuel dilution amount D exceeds a determination value Dc, an alarm lamp 46 is lighted. When the alarm lamp 46 is lighted, an operator replaces the engine oil in order to preclude such occurrence that the progress of the fuel dilution furthermore causes the poor lubricating performance of the engine oil. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification system for construction machinery, and in particular, has a regeneration means for recovering the purification capacity of an exhaust gas purification device, and performs fuel dilution of engine oil by mixing fuel injected during regeneration control with engine oil. The present invention relates to an exhaust gas purification system for construction machinery to prevent.

  In recent years, regulations on engine exhaust gas have been strengthened. Construction machinery is also equipped with an engine, and is further equipped with an exhaust gas purification device to comply with regulations. One of the exhaust gas purification devices is a diesel particulate filter (hereinafter referred to as DPF). The DPF collects particulates such as carbon (hereinafter referred to as PM) contained in the exhaust gas in the exhaust passage and reduces the PM discharged to the outside.

  The PM deposited on the DPF clogs the filter, excessively increases the exhaust pressure, and decreases engine performance and emission performance. Therefore, the temperature of the exhaust gas is appropriately increased so as to recover the decrease in the purification capacity of the DPF, and the PM deposited on the DPF is forcibly burned and removed. This is called DPF regeneration control. In this regeneration control, in order to raise the temperature of the exhaust gas, auxiliary injection called post injection is performed in the cylinder at a timing later than normal combustion, that is, at a timing delayed so that the combustion continues.

  However, at the time of post-injection, part of the fuel injected into the cylinder may flow along the cylinder wall and flow into the oil pan, mix into the engine oil, and cause engine oil fuel dilution. As engine oil fuel dilution progresses, it causes poor lubrication of engine oil.

  In order to prevent such poor lubrication of engine oil, the technique described in Patent Document 1 has been proposed. The exhaust gas purification system described in Patent Document 1 calculates an injection amount based on preset map data, calculates the injection amount by accumulating the injection amount, and the accumulated injection amount has a predetermined determination value. By stopping the injection when it exceeds, the fuel dilution of the engine oil is prevented in advance, and the lubrication failure of the engine oil is prevented.

JP 2007-23874 A

  However, the above prior art has the following problems.

  In the exhaust gas purification system described in Patent Document 1, engine oil fuel dilution can be prevented in advance by stopping injection when the cumulative injection amount exceeds a predetermined determination value. However, since this prior art is a technique for preventing dilution of engine oil itself, even when there is no concern about poor lubrication due to fuel dilution of engine oil, if the cumulative injection amount exceeds a predetermined judgment value, injection is stopped. Playback control is interrupted. For example, in the control where the regeneration is completed in 15 minutes, if the cumulative injection amount exceeds a predetermined determination value after 10 minutes during the regeneration control, the regeneration control is interrupted and combustion is performed with the remaining 5 minutes of regeneration. The PM that was supposed to remain in the DPF. If the DPF is used in the state where it remains, the accumulation of PM proceeds, the regeneration control interval is shortened, the regeneration control is frequently performed, and the fuel is injected each time, so there is a risk of deterioration in fuel consumption.

  An object of the present invention is to provide an exhaust gas purification system capable of preventing poor lubrication of engine oil due to fuel dilution during regeneration control and preventing deterioration in fuel consumption due to regeneration control.

  (1) In order to achieve the above object, the present invention provides an engine, an exhaust gas purification device that captures and purifies PM in exhaust gas discharged from the engine, and regeneration with fuel injection in the engine. In an exhaust gas purification system for a construction machine having a regeneration means for performing control and recovering the purification ability of the exhaust gas purification device, the engine injected by the fuel injected during the regeneration control by the regeneration means into the engine oil A fuel dilution determination means for obtaining a fuel dilution amount of oil and determining whether or not the fuel dilution amount exceeds a predetermined determination value; and determining that the fuel dilution amount exceeds a predetermined determination value in the fuel dilution determination means. Then, a processing means for performing processing for preventing engine oil from being diluted with fuel is provided.

  In the present invention configured as described above, the fuel dilution determining means obtains the fuel dilution amount of the engine oil due to the fuel injected during the regeneration control being mixed into the engine oil, and the fuel dilution amount has a predetermined determination value. Determine whether it has been exceeded. When the fuel dilution determination unit determines that the fuel dilution amount has exceeded a predetermined determination value, the processing unit performs processing for preventing engine oil from being diluted with fuel. As a result, further fuel dilution of the engine oil can be prevented, and poor lubrication of the engine oil due to regeneration control fuel dilution can be prevented.

  Furthermore, in the present invention, the regeneration control interval is shortened in order to prevent the engine oil from being poorly lubricated by calculating the actual fuel dilution amount of the engine oil without interrupting the regeneration itself. In addition, fuel consumption deterioration due to regeneration control can be prevented.

  (2) In the above (1), preferably, when the number of regeneration controls by the regeneration unit exceeds a predetermined number, the fuel dilution determination unit causes the fuel dilution amount of the engine oil to exceed the predetermined determination value. It shall be determined that

  (3) In the above (1), preferably further comprising specific gravity detection means installed in the engine for detecting the specific gravity of engine oil, and temperature detection means installed in the engine for detecting the temperature of the engine oil. The fuel dilution determining means calculates the specific gravity of the engine oil at a standard temperature from the specific gravity of the engine oil obtained by the specific gravity detecting means and the temperature of the engine oil obtained by the temperature detecting means, and the specific gravity of the engine oil and the engine A deviation from the initial specific gravity of the engine oil at the time of oil filling is obtained, and when this deviation exceeds a predetermined value, it is determined that the fuel dilution amount of the engine oil has exceeded the predetermined determination value.

  Thereby, the fuel dilution determination means can determine that the fuel dilution amount has exceeded the predetermined determination value.

  (4) In any one of the above (1) to (3), preferably, the processing means stops the reproduction control by the reproduction means.

  (5) In any one of the above (1) to (3), preferably, the processing means is a warning notification means for notifying a driver that the fuel dilution amount has exceeded a predetermined determination value. .

  Thereby, the processing means can prevent the fuel dilution of the engine oil.

  According to the present invention, it is possible to prevent poor lubrication of engine oil due to fuel dilution at the time of regeneration control and to prevent deterioration of fuel consumption due to regeneration control.

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

<First Embodiment>
~Constitution~
FIG. 1 is an overall system configuration diagram showing an exhaust gas purification system for a construction machine according to a first embodiment of the present invention together with an engine control system. In the present embodiment, the present invention is applied to a hydraulic excavator that is a typical example of a construction machine.

  In FIG. 1, a construction machine (hydraulic excavator) according to the present embodiment includes a diesel engine (hereinafter referred to as an engine) 1, an engine control system 3 that controls the rotational speed and output torque of the engine 1, and exhaust gas from the engine 1. And an exhaust gas purification system 4 for purifying gas.

  The engine 1 drives a hydraulic pump provided in a hydraulic system (not shown), and drives a driven member (described later) such as a front working machine of a hydraulic excavator.

  The engine control system 3 includes an engine control dial 31 that instructs the rotation speed of the engine 1, a rotation speed detection device 32 that detects the actual rotation speed of the engine 1, and a fuel injection device 35 that supplies a predetermined amount of fuel to the engine 1. And a controller 50. The fuel injection device 35 includes a plurality of injectors (not shown) that are provided for each cylinder of the engine 1, and the solenoid valve of each injector is appropriately controlled to open according to a command from the controller 50, so that the fuel injection timing ( The start time and end time) and the injection amount are appropriately controlled.

  The exhaust gas purification system 4 is disposed in an exhaust pipe 41 that constitutes an exhaust system of the engine 1, and includes a filter 42a that captures PM in exhaust gas discharged from the engine 1, and an oxidation catalyst 42b that is located upstream of the filter 42a. , A differential pressure sensor 43 for detecting a differential pressure across the upstream and downstream sides of the filter 42a (pressure loss of the filter 42a), a controller 50, and a warning lamp 46 that is turned on based on an instruction from the controller 50 And have.

  FIG. 2 is a diagram showing the processing contents of the controller 50. The controller 50 constitutes a common control means for the engine control system 3 and the exhaust gas purification system 4, and includes the arithmetic processing functions of the engine control unit 51, the regeneration control unit 52, and the dilution prevention control unit 53, and a recording device. 56.

  The engine control unit 51 normally receives an instruction signal from the engine control dial 31 and a detection signal from the rotation speed detection device 32, performs predetermined arithmetic processing, and outputs a control signal to the fuel injection device 35. To do. Based on the control signal, the fuel injection device 35 injects fuel so that the detected rotational speed detected by the rotational speed detector 32 is maintained at the target rotational speed indicated by the engine control dial 31. The engine control unit 51 also receives a regeneration control signal (a regeneration start signal and a regeneration end signal) from the regeneration control unit 52, performs predetermined arithmetic processing, and outputs a post-injection control signal to the fuel injection device 35. The fuel injection device 35 injects fuel at a timing later than usual based on the control signal.

  The regeneration control unit 52 receives the detection signal from the differential pressure sensor 43, performs a predetermined calculation process, and performs automatic regeneration control to output a regeneration control signal (a regeneration start signal and a regeneration end signal) to the engine control unit 51. The regeneration end signal is output to the dilution prevention control unit 53.

  The dilution prevention control unit 53 inputs a reproduction end signal from the reproduction control unit 52, reads the number of reproductions from the recording device 56 until the previous time, performs a predetermined calculation process, and outputs a control signal to the warning lamp 46.

  FIG. 3 is a flowchart showing the processing contents of the reproduction control unit 52.

  In FIG. 3, the regeneration control unit 52 receives a detection signal from the differential pressure sensor 43 (step S1), and whether or not the differential pressure ΔP across the DPF 42 indicated by the detection signal exceeds the regeneration start determination value ΔP1, that is, ΔP. It is determined whether or not> ΔP1 (step S2). If ΔP> ΔP1 is not satisfied, the process returns to step S1, and the processes of steps S1 and S2 are repeated. If ΔP> ΔP1, it is determined that PM has accumulated in the filter 42a of the DPF 42 over a predetermined amount Wa, and engine control is performed. A reproduction start signal is output to the unit 51 (step S3). When the regeneration start signal is output to the engine control unit 51 in step S3, the engine control unit 51 performs post injection as described above.

  Here, the differential pressure ΔP across the DPF 42 and the PM deposition amount W are in a relationship as shown in FIG. That is, when PM is not deposited on the filter 42a of the DPF 42, there is no differential pressure ΔP due to the effect of the deposited PM, the differential pressure ΔP is the original differential pressure ΔP0 of the DPF 42, and PM is deposited on the filter 42a of the DPF 42. As the accumulation amount W increases, the differential pressure ΔP increases. When the differential pressure ΔP increases to the regeneration start determination value ΔP1, it is determined that the PM accumulation amount of the filter 42a has reached a predetermined amount Wa that requires regeneration. . Here, the relationship between the differential pressure ΔP and the PM deposition amount W shown in FIG. 4 is determined in advance based on experimental data. In FIG. 4, the relationship between the differential pressure ΔP and the PM deposition amount W is shown in a linear proportion for convenience, but the actual relationship between the differential pressure ΔP and the PM deposition amount W is not a linear proportion.

  Next, the regeneration control unit 52 inputs the detection signal from the differential pressure sensor 43 again (step S4), and determines whether or not the differential pressure ΔP is lower than the regeneration end determination value ΔP2, that is, whether ΔP <ΔP2 is satisfied (step S4). Step S5). The regeneration end determination value ΔP2 is a differential pressure of the DPF 42 when the PM accumulated on the filter 42a is burned and removed and the accumulation amount W is reduced to the target amount Wb as shown in FIG. It is. If ΔP <ΔP2, the process returns to step S4, and the processing of steps S4 and S5 is repeated. If ΔP <ΔP2, a regeneration end signal is output to the engine control unit 51 (step S6), and the dilution prevention control unit A reproduction end signal is also output to 53 (step S7).

  FIG. 5 is a flowchart showing the processing contents of the dilution prevention control unit 53.

  In FIG. 5, the dilution prevention control unit 53 determines whether or not the regeneration end signal from the regeneration control unit 52 has been input (step S11). If the regeneration end signal is not input, the process is repeated. When a playback end signal is input, the previous number of times of reproduction recorded in the recording device 56 is read, 1 is added to the value, and the number of times of reproduction (current number of reproductions N) is counted and stored in the recording device 56. (Step S12). Based on the number of regenerations N, a fuel dilution amount D of the engine oil due to the fuel injected at the time of regeneration control being mixed into the engine oil is calculated (step S13), and the fuel dilution amount D exceeds a predetermined determination value Dc. If the fuel dilution amount D does not exceed the predetermined determination value Dc, the process returns to step S11, and the processing of steps S11 to S14 is repeated, so that the fuel dilution amount D is equal to the predetermined determination value Dc. If it exceeds, a lighting signal is output and the warning lamp 46 is turned on (step S15).

  Here, the fuel dilution amount D is a value defined by the following equation, for example.

D = Wf / We
We: Weight of engine oil per unit volume at standard temperature Wf: Weight of fuel contained in engine oil per unit volume at standard temperature We measures, for example, the specific gravity ρe of the engine oil and corrects the specific gravity ρe by temperature correction. It is obtained by converting the specific gravity ρe _t0 at the standard temperature into a weight. Wf is a deviation Δρ specific gravity .rho.e _t temperature corrected engine oil at that time with respect to the specific gravity of the engine oil (Original Gravity) at standard temperature that is not contaminated, for example, fuel, obtained by converting the Δρ weight.

  The number N of regenerations and the fuel dilution amount D have a relationship as shown in FIG. That is, if the regeneration is not performed, the fuel is not mixed into the engine oil, and the fuel dilution amount is 0. When the regeneration is performed, the fuel from the post injection is mixed into the engine oil, and the engine oil is absorbed by the fuel. Diluted. The fuel dilution amount D increases as the number of regenerations N increases. Here, as the fuel dilution amount D increases, the engine oil becomes thinner and the lubrication performance as the engine oil decreases. If engine oil fuel dilution progresses to a certain extent, the lubricating performance as engine oil cannot be achieved properly. In the present embodiment, the fuel dilution amount at that time is set as the determination value Dc, and if the fuel dilution amount D exceeds the determination value Dc, it is determined that there is a possibility that lubrication failure due to fuel dilution may occur. The relationship between the number of regenerations N and the fuel dilution amount D shown in FIG. 6 is also determined in advance based on experimental data. In FIG. 6, the relationship between the number of regenerations N and the fuel dilution amount D is shown in a linear proportion for convenience, but the relationship between the actual number of regenerations N and the fuel dilution amount D is not in a linear proportion.

  In the above, the DPF 42 shown in FIG. 1 constitutes an exhaust gas purification device that captures and purifies PM in the exhaust gas discharged from the engine 1, and includes the fuel injection device 35, the differential pressure sensor 43, and the like shown in FIG. 2, among the processes of the engine control unit 51 of the controller 50 shown in FIG. 2 and the regeneration control unit 52 of the controller 50, the processes of steps S <b> 1 to S <b> 6 shown in FIG. 3 perform regeneration control with fuel injection in the engine 1. The regeneration means for recovering the purification ability of the DPF 42 is configured.

  2 out of the processing of the reproduction control unit 52 of the controller 50 shown in FIG. 2 and step S11 shown in FIG. 5 of the processing of the recording apparatus 56 and the dilution prevention control unit 53 of the controller 50 shown in FIG. The process of ~ S14 calculates the fuel dilution amount of the engine oil due to the fuel injected during the regeneration control by the regeneration means being mixed into the engine oil, and determines whether the fuel dilution amount exceeds a predetermined determination value Of the processes of the warning lamp 46 shown in FIG. 1 and the dilution prevention control unit 53 of the controller 50, the process of step S15 shown in FIG. 5 is performed in the fuel dilution judging means. If it is determined that the determination value has been exceeded, a processing means for performing processing for preventing fuel dilution of engine oil is configured.

  FIG. 7 is a diagram showing an external appearance of a hydraulic excavator provided with 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 cab 107, the engine 1 is arranged in the engine room 106, and a warning lamp 46 is arranged in the cab 107. 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 115.

~ Operation ~
The operation of playback control according to this embodiment will be described. Exhaust gas from the engine 1 is guided to the DPF 42 via the exhaust pipe 41, and PM contained in the exhaust gas is collected by the filter 42a of the DPF 42. As the accumulation of PM in the DPF 42 progresses, the filter 42a becomes clogged, the differential pressure ΔP increases, and the performance of the engine 1 decreases.

  The regeneration control unit 52 of the controller 50 always inputs the detection signal of the differential pressure sensor 43 while the engine 1 is operating, and determines that regeneration needs to be started when the differential pressure ΔP exceeds the regeneration start determination value ΔP1. Then, a regeneration start signal is output to the engine control unit 51 (S 1 → S 2 → S 3), and the engine control unit 51 outputs a control signal for starting post injection to the fuel injection device 35. As a result, regeneration of the DPF 42 starts. That is, the fuel injection device 35 performs post injection into the exhaust pipe 41 at a timing later than that of normal combustion, raises the temperature of the exhaust gas by this post injection, and supplies unburned fuel to the oxidation catalyst 42b to be oxidized. The exhaust gas temperature is further raised by the reaction heat, and the PM deposited on the filter 42a is burned and removed by the high temperature exhaust gas.

  When the PM accumulated on the filter 42a is burned and removed after the regeneration is started, the differential pressure ΔP decreases. The regeneration control unit 52 inputs the detection signal of the differential pressure sensor 43. When the differential pressure ΔP becomes lower than the regeneration end determination value ΔP2, the regeneration control unit 52 determines that the regeneration needs to be terminated, and sends a regeneration end signal to the engine control unit 51. (S4 → S5 → S6), the engine control unit 51 outputs a control signal for terminating the post injection to the fuel injection device 35. Thereby, the reproduction ends.

  When regeneration is performed as described above, a part of the fuel injected into the cylinder by post injection flows along the cylinder wall to the oil pan, mixes with the engine oil, and dilutes the engine oil. In the present embodiment, the dilution prevention control unit 53 of the controller 50 inputs a regeneration end signal from the regeneration control unit 52 every time regeneration is completed, counts the number of regenerations N, and fuels based on the regeneration number N. The dilution amount D is calculated (S7 → S11 → S12 → S13). When the fuel dilution amount D exceeds the determination value Dc, the warning lamp 46 is turned on (S14 → S15).

  When the warning lamp 46 is lit, the operator replaces the engine oil in order to prevent further dilution of the fuel and poor lubrication of the engine oil.

  When the operator presses a reset button (not shown) when the engine oil is changed, the warning lamp 46 is turned off, and the number of times of reproduction N stored in the recording device 56 becomes zero.

~effect~
As described above, in the present embodiment, the fuel dilution amount D is calculated based on the number of regenerations N, and if it is determined that the fuel dilution amount D of the engine oil has exceeded a predetermined determination value Dc, the warning lamp 46 is turned on. Turns on and prompts the operator to perform appropriate processing to prevent further fuel dilution of engine oil, such as engine oil replacement, and prevents engine oil lubrication failure due to fuel dilution during regeneration control .

  Further, in the present embodiment, the regeneration itself does not interrupt the regeneration, and by estimating the fuel dilution amount of the engine oil to prevent poor lubrication of the engine oil, the regeneration control interval is not shortened, It is possible to prevent fuel consumption deterioration due to regeneration control.

<Second Embodiment>
~Constitution~
FIG. 8 is an overall system configuration diagram showing an exhaust gas purification system for a construction machine according to a second embodiment of the present invention together with an engine control system. In the figure, components equivalent to those shown in FIG. 8, the construction machine (hydraulic excavator) according to the present embodiment includes an exhaust gas purification system 4A. The exhaust gas purification system 4A includes an engine 1 in addition to the configuration of the exhaust gas purification system 4 shown in FIG. A specific gravity sensor 47 that is installed in the oil pan and detects the specific gravity of the engine oil in the oil pan, and a temperature sensor 48 that is installed in the oil pan of the engine 1 and detects the temperature of the engine oil in the oil pan. And a controller 50A instead of the controller 50.

  FIG. 9 is a diagram showing the processing contents of the controller 50A. In FIG. 9, the same components as those shown in FIG. The controller 50A has calculation processing functions of a regeneration control unit 52A and a dilution prevention control unit 53A in place of the regeneration control unit 52 and the dilution prevention control unit 53 of FIG.

  FIG. 10 is a flowchart showing the processing contents of the reproduction control unit 52A. In FIG. 10, the same components as those shown in FIG. The difference between the flowchart shown in FIG. 10 and the flowchart shown in FIG. 3 is that the process in step S7 in the flowchart shown in FIG. 3 is eliminated and the process in step S21 is newly added. That is, in FIG. 10, the regeneration control unit 52A determines in step S5 whether or not the differential pressure ΔP has become lower than the regeneration end determination value ΔP2, that is, whether ΔP <ΔP2, and if not ΔP <ΔP2. Then, it is determined whether or not a reproduction prohibition flag (described later) is set (step S21). If the reproduction prohibition flag is not set, the process returns to step S4, and the processes of steps S4 and S5 are repeated. If the regeneration prohibition flag is set, a regeneration end signal is output to the engine control unit 51 (step S6).

  FIG. 11 is a flowchart showing the processing contents of the dilution prevention control unit 53A.

In FIG. 11, the dilution prevention control unit 53A inputs a detection signal from the specific gravity sensor 47 and a detection signal from the temperature sensor 48 (step S31), and the specific gravity ρe of the engine oil obtained from the detection signal of the specific gravity sensor 47. the performs temperature compensation by the temperature at that time was determined from the temperature sensor 48, it is calculated in terms of the specific gravity .rho.e _t0 at standard temperature (step S32). Then, calculate the deviation Δρ specific gravity .rho.e _t0 calculated in step S32 with respect to the initial gravity .rho.e ₀ of the engine oil at standard temperature (step S33), a specific gravity deviation Δρ it is determined whether more than a predetermined judgment value Derutaroshi (step S34) If the specific gravity deviation Δρ does not exceed the predetermined determination value Δρc, the process returns to step S31, the processing of steps S31 to S34 is repeated, and if the specific gravity deviation Δρ exceeds the predetermined determination value Δρc, the regeneration prohibition flag Is set (step S35), a lighting signal is output, and the warning lamp 46 is turned on (step S36). The initial specific gravity ρe ₀ is a value specific to engine oil and is stored in the memory of the controller 50A.

  Here, the specific gravity deviation Δρ and the fuel dilution amount D have a relationship as shown in FIG. That is, since the fuel is not mixed in the engine oil when the engine oil is filled, the fuel dilution amount D is 0 and the specific gravity deviation Δρ is 0. When regeneration is performed, fuel from the post-injection is mixed into the engine oil, and the engine oil is diluted with the fuel to generate a specific gravity deviation Δρ. The specific gravity deviation Δρ increases with an increase in the number of regenerations and an increase in the fuel dilution amount D. Here, as the fuel dilution amount D increases, the engine oil becomes thinner, and the lubricating performance as the engine oil decreases. If the engine oil fuel dilution proceeds to a certain extent, the engine oil will not be able to adequately perform the lubrication performance. In this embodiment, the specific gravity deviation Δρ corresponding to the fuel dilution amount Dc at that time is set as the determination value Δρc, and when the specific gravity deviation Δρ exceeds the determination value Δρc, the fuel dilution amount D of the engine oil becomes the determination value Dc. And it is determined that there is a possibility of poor lubrication due to fuel dilution. The relationship between the specific gravity deviation Δρ and the fuel dilution amount D shown in FIG. 12 is also determined in advance based on experimental data. In FIG. 12, for convenience, the relationship between the specific gravity deviation Δρ and the fuel dilution amount D is shown in a linear proportion, but the actual relationship between the specific gravity deviation Δρ and the fuel dilution amount D is not a linear proportion.

  In the above, the DPF 42 shown in FIG. 8 constitutes an exhaust gas purification device that captures and purifies PM in the exhaust gas discharged from the engine 1, and includes the fuel injection device 35, the differential pressure sensor 43, and the like shown in FIG. Of the processes of the engine controller 51 of the controller 50A shown in FIG. 9 and the regeneration controller 52A of the controller 50A, the processes of steps S1 to S3 and steps S4 to S6 shown in FIG. Regeneration means that performs regeneration control and restores the purification ability of the DPF 42 is configured. The specific gravity sensor 47 is installed in the engine 1 to configure specific gravity detection means that detects the specific gravity of the engine oil, and the temperature sensor 48 is the engine 1. And constitutes temperature detecting means for detecting the temperature of the engine oil.

  Further, among the processes of the dilution prevention control unit 53A of the controller 50A shown in FIG. 9, the processes of steps S31 to S34 shown in FIG. 11 are performed by mixing the fuel injected during the regeneration control by the regeneration means into the engine oil. The fuel dilution determination means for determining whether or not the fuel dilution amount has exceeded a predetermined determination value is configured, and the process shown in FIG. 10 of the processing of the regeneration control unit 52A of the controller 50A shown in FIG. Of the processing of step S21 and step S6, and the processing of the dilution prevention control unit 53A of the controller 50A, the processing of steps S35 and S36 shown in FIG. If it is determined that the determination value is exceeded, a processing unit that performs processing to prevent engine oil from being diluted with fuel Constitute a.

~ Operation and effect ~
The basic operation of the regeneration control of this embodiment is the same as that of the first embodiment (S1->S2->S3->S4->S5-> S6), but the difference is that it prevents the engine oil from being diluted with fuel. As a process for this, the reproduction control is automatically stopped. That is, the dilution prevention control unit 53A of the controller 50A receives the detection signals from the specific gravity sensor 47 and the temperature sensor 48, corrects the temperature, and calculates the specific gravity deviation Δρ (S21 → S22 → S23). When the specific gravity deviation Δρ exceeds a predetermined determination value Δρc, the regeneration prohibition flag is set and the warning lamp 46 is turned on (S24 → S25 → S26).

  In the regeneration control, if the differential pressure ΔP is not lower than the regeneration end determination value ΔP2, it is determined that the regeneration needs to be continued (S4 → S5). In this state, if the reproduction prohibition flag is not set, the reproduction is continued (S31 → S4 → S5), but if the reproduction prohibition flag is set, the engine control unit 51 is used even when the reproduction needs to be continued. Is output (S31 → S6), and the engine control unit 51 outputs a control signal for terminating the post-injection to the fuel injection device 35. Thereby, the reproduction is forcibly terminated (automatic stop).

  When the warning lamp 46 is lit, the operator is notified that the automatic regeneration has been stopped and that the engine oil needs to be replaced, and the operator replaces the engine oil. When the operator presses a reset button (not shown) when the engine oil is changed, the warning lamp 46 is turned off and the prohibition flag in the regeneration control unit 52A is released.

  As described above, also in this embodiment, the same effect as that of the first example can be obtained.

Further, in the present embodiment, an appropriate process for preventing further fuel dilution of engine oil, such as automatically stopping the regeneration control by setting a regeneration prohibition flag, is performed, and the engine by the fuel dilution during the regeneration control is performed. Oil lubrication can be prevented.
<Other embodiments>
Although several embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications are possible within the spirit of the present invention. The modification is demonstrated below.

  1. In the first embodiment, the exhaust gas purification system 4 always inputs the detection signal of the differential pressure sensor 43 during the operation of the engine 1 regardless of whether or not there is work, and the differential pressure ΔP is determined to start regeneration. Although regeneration is started when the value ΔP1 is exceeded (automatic regeneration control), manual regeneration control may be combined. For example, a manual regeneration switch is provided in the cab 107, and the automatic regeneration control based on the regeneration start determination value ΔP1 is performed only when the operator operates the operation lever. When the operator does not operate the operation lever, the automatic regeneration control is performed. The manual regeneration control is started when the operator operates the manual regeneration switch.

  In manual regeneration control, it is necessary to inform the operator that manual regeneration is necessary. As an example of the method, a value larger than the regeneration start determination value ΔP1 of the automatic regeneration control is preset as the manual regeneration start determination value ΔP3, and if the detected differential pressure ΔP exceeds the manual regeneration start determination value ΔP3, a warning is given. There is a method of lighting the lamp and urging the operator to perform manual regeneration. In this case, since the judgment value is different between automatic regeneration and manual regeneration, the total amount of fuel that is post-injected in one regeneration control is different, and as a result, the fuel dilution amount of engine oil in one regeneration control is also different. . Therefore, when performing automatic regeneration control and manual regeneration control using different determination values, it is necessary to calculate the number of regenerations in consideration of the difference in the fuel dilution amount. For example, if the number of playbacks is corrected according to the difference (for example, ratio) between the judgment values of automatic regeneration control and manual regeneration control, and the total number of playbacks is obtained by adding the corrected number of playbacks to the number of playbacks of automatic playback control. Good.

  2. In the first embodiment, when the fuel dilution amount D exceeds the determination value Dc, the warning lamp 46 is turned on to prompt the operator to change the engine oil. However, a regeneration manual stop switch is further provided to control regeneration. You may make it prohibit starting. Further, instead of providing a regeneration manual stop switch, a regeneration prohibition flag may be set to automatically prohibit activation of regeneration control as in the second embodiment.

  3. In the first embodiment, the engine oil fuel dilution amount D is calculated based on the number of regenerations N, and it is determined whether the engine oil fuel dilution amount D exceeds a predetermined determination value Dc. A determination value Nc of the number of reproductions corresponding to the amount determination value Dc may be set, and it may be determined whether or not the number of reproductions N exceeds the determination value Nc.

  4). In the second embodiment, a specific gravity deviation Δρ is calculated, a specific gravity deviation determination value Δρc corresponding to the fuel dilution amount determination value Dc is set, and whether or not the specific gravity deviation Δρ exceeds the determination value Δρc is determined. However, the engine oil fuel dilution amount D may be calculated based on the specific gravity deviation Δρ to determine whether or not the engine oil fuel dilution amount D has exceeded a predetermined determination value Dc.

  5. In the second embodiment, the warning lamp 46 is turned on and the regeneration prohibition flag is set to automatically prohibit the activation of the regeneration control. However, as in the first embodiment, the warning lamp 46 is turned on. It is also possible to light up only. In this case, the determination as to whether or not to turn on the warning lamp 46 may be made every time the reproduction ends as in the first embodiment, or during the reproduction control as in the second embodiment. You may judge.

  6). In the first and second embodiments, when the fuel dilution amount D or the specific gravity deviation Δρ exceeds the determination values Dc and Δρc, the warning lamp 46 is turned on, but a buzzer or the like may be sounded, You may display that on the display screen of a display apparatus.

  Also in the embodiment as described above, it is possible to prevent poor lubrication of the engine oil due to fuel dilution at the time of regeneration control and to prevent deterioration of fuel consumption due to regeneration control.

1 is an overall system configuration diagram showing an exhaust gas purification system for a construction machine according to a first embodiment of the present invention together with an engine control system. It is a figure which shows the processing content of a controller. It is a flowchart which shows the processing content of a reproduction | regeneration control part. It is a figure which shows the relationship between the differential pressure | voltage of DPF, and the deposition amount of PM. It is a flowchart which shows the processing content of a dilution prevention control part. It is a figure which shows the relationship between the frequency | count of regeneration, and fuel dilution amount. It is a figure which shows the external appearance of the hydraulic shovel provided with the system shown in FIG. It is a whole system block diagram which shows the exhaust-gas purification system of the construction machine concerning 2nd Embodiment of this invention with an engine control system. It is a figure which shows the processing content of a controller. It is a flowchart which shows the processing content of a reproduction | regeneration control part. It is a flowchart which shows the processing content of a dilution prevention control part. It is a figure which shows the relationship between the deviation of specific gravity, and fuel dilution amount.

Explanation of symbols

1 Engine 3 Engine control system 4, 4A Exhaust gas purification system 31 Engine control dial 32 Rotational speed detection device 35 Fuel injection device 41 Exhaust pipe 42 DPF
42a Filter 42b Oxidation catalyst 43 Differential pressure sensor 46 Warning light 47 Specific gravity sensor 48 Temperature sensor 50, 50A Controller 51 Engine control unit 52, 52A Regeneration control unit 53, 53A Dilution prevention control unit 56 Recording device

Claims (5)

An engine, an exhaust gas purification device that captures and purifies PM in exhaust gas discharged from the engine, and regeneration control that involves fuel injection in the engine is performed to recover the purification capability of the exhaust gas purification device In an exhaust gas purification system for a construction machine equipped with a regeneration means,
A fuel dilution determination means for determining a fuel dilution amount of the engine oil due to mixing of the fuel injected during the regeneration control by the regeneration means into the engine oil, and determining whether the fuel dilution amount exceeds a predetermined determination value;
A construction machine comprising processing means for performing processing for preventing fuel dilution of engine oil when the fuel dilution determination means determines that the fuel dilution amount exceeds a predetermined determination value. Exhaust gas purification system. The exhaust gas purification system for a construction machine according to claim 1,
The fuel dilution determining means determines that the fuel dilution amount of the engine oil has exceeded the predetermined determination value when the number of regeneration controls by the regeneration means exceeds a predetermined number. Gas purification system. The exhaust gas purification system for a construction machine according to claim 1,
A specific gravity detecting means installed in the engine for detecting the specific gravity of the engine oil; and a temperature detecting means installed in the engine for detecting the temperature of the engine oil;
The fuel dilution determining means calculates the specific gravity of the engine oil at a standard temperature from the specific gravity of the engine oil obtained by the specific gravity detecting means and the temperature of the engine oil obtained by the temperature detecting means, and the specific gravity of the engine oil and the engine oil are calculated. A deviation from the initial specific gravity of engine oil at the time of filling is obtained, and when this deviation exceeds a predetermined value, it is determined that the fuel dilution amount of the engine oil has exceeded the predetermined determination value. Exhaust gas purification system. The exhaust gas purification system according to any one of claims 1 to 3,
The exhaust gas purification system for a construction machine, wherein the processing means stops the regeneration control by the regeneration means. The exhaust gas purification system according to any one of claims 1 to 3,
The exhaust gas purification system for a construction machine, wherein the processing means is a warning notification means for notifying a driver that the fuel dilution amount has exceeded a predetermined determination value.

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