JP2006057476A - Engine determining degree of clogging of exhaust particulate collector by supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine capable of determining degree of clogging of an exhaust particulate collector without providing the exhaust particulate collector with a special pressure detection means. <P>SOLUTION: In the engine provided with a supercharger controlling charge pressure to a target by an exhaust turbine provided with a variable nozzle, degree of clogging of the exhaust particulate collector is determined by opening of the variable nozzle. When degree of clogging reaches a predetermined limit value, engine operation is switched to regeneration operation mode for eliminating clogging. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine (hereinafter referred to as an engine), and more particularly, to determining clogging of a particle collector provided in an exhaust system of an engine.

If the engine exhaust system is equipped with a particle collector that collects particles in the exhaust, the particle collector will clog due to the accumulation of collected particles when the engine is operated for a certain period of time. It is necessary to regenerate the accumulated particles by burning them. Regarding the regeneration of the particle collector by burning the particles accumulated in the particle collector, the motor of the electric air pump that supplies the combustion air, the microcomputer that outputs the low frequency duty signal, and the high frequency pulse signal Patent Document 1 below describes that control is performed by a control circuit including a gate that outputs a logical product of a low-frequency duty signal and a high-frequency pulse signal from a high-frequency pulse signal generation circuit that outputs a high-frequency pulse signal. Further, in Patent Document 2 below, in order to judge the degree of clogging of the exhaust gas purification device, the pressure on the upstream side and the downstream side of the exhaust gas purification device is detected by the pressure detection means, and the ratio of the respective pressures is calculated. It is described that the degree of clogging is determined by sequentially averaging the ratio.
JP 7-150930 A JP-A-9-13947

  If pressure detection means are provided on the upstream side and the downstream side of the exhaust gas purification device, clogging of the exhaust gas purification device can be determined not only by the method of Patent Document 2 but in various ways. However, in order to provide the pressure detection means on the upstream side and the downstream side of the exhaust gas purification device, a certain amount of cost is required.

  An object of the present invention is to provide an engine capable of determining clogging of an exhaust particle collector without requiring such special pressure detection means.

  In order to solve the above-described problems, the present invention provides an engine including a supercharging device whose supercharging pressure is target-controlled by an exhaust turbine including a variable nozzle and an exhaust particle collector. The present invention proposes an engine characterized in that the degree of clogging of the exhaust gas collector is judged from the opening degree.

  Such an engine may be switched to an operation mode in which the exhaust particle collector is regenerated when the variable nozzle opening is reduced to a predetermined limit value. In this case, the switching to the regeneration mode may be terminated when the variable nozzle opening is restored by a predetermined deviation from the limit value.

  Further, such an engine may be adapted to perform an opening degree test of the variable nozzle at the start of operation. This opening degree test may be performed by instructing the variable nozzle actuator to fully close the variable nozzle and measuring the displacement of the actuator. Further, the limit value of the variable nozzle opening degree may be corrected based on the opening degree test.

  If the exhaust turbine of the turbocharger is equipped with a variable nozzle and the supercharging pressure is targeted, the exhaust particle collector clogged in the exhaust system becomes clogged and the exhaust turbine back pressure Since the output of the exhaust turbine is less likely to increase as the engine speed increases, the variable nozzle opening decreases so that the variable nozzle is more narrowed (ie, closed). Therefore, the degree of clogging of the exhaust particle collector can be determined from the opening of the variable nozzle.

  When the variable nozzle opening is reduced to the predetermined limit value, the engine operation can be switched to the operation mode to regenerate it, and when the degree of clogging of the exhaust gas collector reaches the predetermined limit That can be played automatically. In addition, if switching to the regeneration mode is terminated when the variable nozzle opening returns by a predetermined deviation from the limit value, the degree of elimination of clogging of the exhaust particle collector can be similarly increased. Judging by the change in the degree, the engine operation can be returned from the regeneration mode to the normal operation.

  If the variable nozzle opening degree test is performed at the start of operation, there is play in the variable nozzle opening / closing mechanism, and even when it changes due to temperature or wear due to the operation of the variable nozzle opening / closing mechanism, it is variable. The determination of the degree of clogging of the exhaust gas collector due to the nozzle opening being reduced to a predetermined limit value can always be performed accurately as scheduled. If the opening test is performed by instructing the variable nozzle actuator to fully close the variable nozzle and measuring the displacement of the actuator, the variable nozzle opening is reduced to a predetermined limit value, that is, the variable nozzle is large. The variable nozzle opening / closing mechanism can be accurately verified in the light of a clear opening degree that is close to the closed (closed) state. If the limit value of the variable nozzle opening is corrected on the basis of the opening degree test, the test result can be accurately reflected for the purpose.

  FIG. 1 attached herewith is a schematic view showing one embodiment in which the engine of the present invention is implemented in a vehicle diesel engine. In the figure, 10 is a four-cylinder diesel engine, which is supplied with intake air via an intake manifold 12 branched into four, injects fuel with four fuel injection valves 14, and collects exhaust from the four cylinders. Exhaust gas is discharged through the exhaust manifold 16. Exhaust gas is supplied from an exhaust manifold 16 to an exhaust turbine 22 having a variable nozzle 20 through an exhaust pipe 18 via the exhaust nozzle. Exhaust gas that has exited the exhaust turbine 22 is passed through an exhaust particle collector 24 and, if necessary, is discharged to the atmosphere via another exhaust purification device.

  The intake air is taken into a supercharged compressor 28 via an air cleaner 26, and the supercharged compressor is pressurized by being driven by an exhaust turbine 22, and is supplied to an engine cylinder from an intake manifold 12 via an intake pipe 30.

  The ECU 32 is an electronic control unit provided with a microcomputer, and a signal indicating an accelerator opening from an accelerator opening sensor for detecting a depression amount of an accelerator pedal not shown by the driver, which is shown in the figure. A signal indicating the vehicle speed from the vehicle speed sensor not being received, a signal indicating the engine rotation speed from the engine rotation speed sensor 34, and a signal indicating the intake pressure (supercharging pressure) in the intake pipe 30 from the intake pressure sensor 36 are received. The control calculation is performed based on the control program incorporated therein, the fuel injection amount is calculated to operate the fuel injection valve 14, the target boost pressure is calculated, and this is detected by the intake pressure sensor 36. The actual boost pressure is compared, and the opening degree of the variable nozzle 20 is controlled so that the actual boost pressure matches the target boost pressure.

  FIG. 2 is a schematic diagram showing an exploded view of an example of one basic structure of a variable nozzle type exhaust turbine such as the combination of the exhaust turbine 22 and the variable nozzle 20 in FIG. The exhaust turbine includes a turbine rotor 40 that is supported by a rotating shaft 38 and rotates around the central axis in the clockwise direction in the drawing, and a housing 42 that surrounds the turbine rotor 40. The housing 42 introduces exhaust gas from the exhaust inlet 44 toward the turbine rotor and distributes it around the turbine rotor by the annular chamber space 46, and by this, a row of movable vanes 48 arranged in the annular chamber space. Exhaust gas is blown around the turbine rotor through a variable nozzle 50 formed between them. The movable vane 48 is supported by the vane shaft 52, and the vane shaft is rotatably supported by the housing 42, so that the movable vane 48 is tilted around the axis of the vane shaft, thereby increasing the opening of the variable nozzle 50. It changes with the inclination.

  More specifically, a vane rotation lever 54 is attached to one end portion of each vane shaft 52, and a short cylindrical cam follower 56 provided at the free end portion is formed along the inner peripheral edge of the unison ring 58. The unison ring 58 is engaged with the cam groove 60, and the unison ring 58 is rotated by the actuator 62 via the unison ring drive lever 64 so that the vane rotation levers 54 are tilted all at once. It has become. The unison ring drive lever 64 is pivotally supported and tilted from the housing at its central portion 66, and is connected at one end thereof to the actuating rod 68 of the actuator 62 by the pivot connecting portion 70, and at its free end portion. A short cylindrical cam follower 72 provided there engages with a cam groove 74 provided on the outer edge of the unison ring 58.

  As in the above example, the vane rotation lever 54 of each movable vane 48 is engaged with the cam groove 60 of the unison ring by the cam follower 56 at its free end, and the unison ring drive lever 64 is at its free end. When the tilt angle of each movable vane is changed by the actuator 62 by engaging with the cam groove 74 of the unison ring by the cam follower 72, the cam follower 56 and the cam groove 60 are engaged, and the cam follower 72 and the cam groove The engagement of 74 is inevitably accompanied by a certain amount of play, and changes due to the air temperature and wear caused by the operation of the variable nozzle opening / closing mechanism, so that the variable nozzle is controlled by a control device such as the electronic control device 32 of FIG. It is preferable that the opening degree command to be issued includes a correction for such play.

  In order to correct such a command, it is necessary to verify the variable nozzle opening degree for each individual product. For this purpose, as an example, the actuator 62 is operated so that the operating rod 68 is in a state indicated by a dotted line every time the operation is started, and the movable vane 48 is indicated by a dotted line so that the variable nozzle opening becomes zero. As shown, the actuator is brought to the fully closed position, and the position of the actuator operating rod 68 at that time may be verified as a position where the variable nozzle opening is zero.

  FIG. 3 shows that the engine according to the present invention judges the degree of clogging of the exhaust particle collector while the variable nozzle opening degree test at the start of operation described above is performed, and the degree of clogging is a predetermined limit. It is a flowchart which shows the point to be operated about one embodiment in the case of a diesel engine, reproducing it, when reaching to.

  When the control is started, it is determined in step 10 whether or not the flag F1 is 1. This flag is set to 1 in step 40, which will be described later. In this type of control, this flag is reset to 0 once at the start of the control. If the answer is NO, the answer is no and control proceeds to step 20. In step 20, the variable nozzle opening / closing means such as the actuator 62 is operated to fully close the variable nozzle. Control then proceeds to step 30 where the variable nozzle opening / closing deviation such as the above play is checked, and a correction value ΔRo for the variable nozzle opening command is obtained. The correction value ΔRo is used in steps 110 and 150 described later. Control then proceeds to step 40, where flag F1 is set to 1. Therefore, after that, control is performed by bypassing steps 20-40.

  In step 50, the fuel injection amount and the target boost pressure Pst are calculated from the accelerator opening, the vehicle speed, and the engine speed.

  Control then proceeds to step 60, where it is determined whether the actual boost pressure Ps actually measured by a boost pressure sensor such as the boost pressure sensor 36 of FIG. 1 is lower than the target boost pressure Pst calculated above. Is done. If the answer is yes, control proceeds to step 70 where the current variable nozzle opening is gradually reduced. If the current variable nozzle opening is Rv, this is to reduce it by the minute opening δR for each control that passes through this flowchart. Conversely, if the answer to step 60 is no, the control proceeds to step 80, where it is determined whether or not the actual boost pressure Ps is higher than the target boost pressure Pst calculated above. If the answer is yes, control proceeds to step 90 where the current variable nozzle opening is gradually increased. If the current variable nozzle opening is Rv, this is to increase it by a minute opening δR for each control that passes through this flowchart. If the answer to step 80 is no, this indicates that the actual boost pressure Ps coincides with the target boost pressure Pst calculated above, so the control proceeds to step 100 as it is.

  In any case, in the next step 100, it is determined whether or not the flag F2 is 1. This flag is set to 1 in step 140 to be described later. Until then, the answer to this step is no, and the control proceeds to step 110. In step 110, it is determined whether or not the current variable nozzle opening degree Rv is larger than a value obtained by subtracting the correction value ΔRo obtained in step 30 from a certain predetermined limit value Rvc. This is to determine whether or not the variable nozzle opening degree has decreased to a predetermined limit value Rvc, taking into account the variable nozzle opening / closing deviation correction value ΔRo tested in step 30. If the answer is yes, this indicates that the degree of clogging of the exhaust particle collector has not yet reached the predetermined limit, so control proceeds to step 120 and normal engine operation is performed.

  On the other hand, if the answer to step 110 is no, this indicates that the degree of clogging of the exhaust particle collector has reached a predetermined limit, so control proceeds to step 130 where the fuel injection amount is increased and the exhaust gas is increased. The engine operation such as increasing the gas temperature is switched to an operation mode that promotes regeneration of the exhaust particle collector (DPF). At this time, the control further proceeds to step 140, and the flag F2 is set to 1.

  When the engine operation in the exhaust particle collector regeneration mode is started, the clogging of the exhaust particle collector is gradually resolved, the exhaust turbine back pressure decreases, the exhaust turbine output increases, and the actual boost pressure Therefore, the control proceeds from step 60 through steps 80 and 90, and the variable nozzle opening Rv gradually increases. Since the flag F2 is set to 1 during the exhaust particle collector regeneration mode operation, the control proceeds from step 100 to step 150, and the variable nozzle opening degree Rv is set to a predetermined value from the limit value Rvc including the correction value ΔRo. It is determined whether or not the reproduction deviation ΔRr has increased. While the answer is no, the control proceeds to step 130 and the operation in the exhaust particle collector regeneration mode is continued, but the regeneration of the exhaust particle collector proceeds and when the answer of step 150 changes from no to yes, Control continues to step 160 where flag F2 is reset to zero. Therefore, after this, control proceeds from step 100 to step 110, and the answer is yes, so control proceeds to step 120, and the engine is returned to normal operation.

  FIG. 4 shows that when the variable nozzle opening Rv is decreased due to the progress of clogging of the exhaust particle collector as the engine operation continues, and when the variable nozzle opening Rv is decreased to a predetermined limit value Rvc including the correction value ΔRo, When the particle collector is regenerated, and the clogging of the exhaust particle collector is recovered to a position corresponding to the regeneration deviation ΔRr when viewed at the variable nozzle opening, the regeneration is terminated and the control is performed by the above steps 60 to 160. 5 is a graph illustrating a state in which the state of clogging of the exhaust gas collector is changed by the variable nozzle opening with respect to the time axis.

  While the present invention has been described in detail with respect to one embodiment thereof, it will be apparent to those skilled in the art that various modifications can be made within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows one embodiment which implemented the engine of this invention in the diesel engine for vehicles. 1 is a schematic diagram showing an example of one basic structure of a variable nozzle type exhaust turbine in an exploded view. The engine according to the present invention determines the degree of clogging of the exhaust particle collector, and regenerates the clogging degree when it reaches a predetermined limit. The flowchart shown about one embodiment. The graph which illustrated the progress of clogging of the exhaust particle collector accompanying continuation of engine operation, and a mode that it will be recovered when it reaches a predetermined limit with the variable nozzle opening with respect to a time axis.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... 4-cylinder diesel engine, 12 ... Intake manifold, 14 ... Fuel injection valve, 16 ... Exhaust manifold, 18 ... Exhaust pipe, 20 ... Variable nozzle, 22 ... Exhaust turbine, 24 ... Exhaust particle collector, 26 ... Air cleaner 28 ... Supercharged compressor, 30 ... Intake pipe, 32 ... Electronic controller, 34 ... Engine speed sensor, 36 ... Intake pressure sensor, 38 ... Rotary shaft, 40 ... Turbine rotor, 42 ... Housing, 44 ... Exhaust introduction Mouth, 46 ... annular chamber space, 48 ... movable vane, 50 ... variable nozzle, 52 ... vane shaft, 54 ... vane rotating lever, 56 ... cam follower, 58 ... unison ring, 60 ... cam groove, 62 ... actuator, 64 ... Unison ring drive lever, 66 ... Lever center, 68 ... Actuator rod, 70 ... Pivot connection, 72 ... Cam for Wa, 74 ... cam groove

Claims (6)

  An engine having a supercharging device whose exhaust pressure is controlled by an exhaust turbine equipped with a variable nozzle and an exhaust particle collector, and the degree of clogging of the exhaust particle collector due to the opening of the variable nozzle An engine characterized by being able to judge.   2. The engine according to claim 1, wherein when the variable nozzle opening is reduced to a predetermined limit value, the engine is switched to an operation mode in which the exhaust particle collector is regenerated.   3. The engine according to claim 2, wherein the switching to the regeneration mode is finished when the variable nozzle opening is restored by a predetermined deviation from the limit value.   The engine according to any one of claims 1 to 3, wherein the opening degree of the variable nozzle is verified at the start of operation.   The engine according to claim 4, wherein the opening degree test is performed by instructing the variable nozzle actuator to fully close the variable nozzle and measuring the displacement of the actuator. 6. The engine according to claim 4, wherein the limit value of the variable nozzle opening is corrected based on the opening test.

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