JP2003021000A - Exhaust gas re-circulating device of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control an EGR valve and a stationary blade rotating means properly while executing the operation responsively during the transient operation of an engine. SOLUTION: The engine has a turbocharger 11, an EGR device 21, and a controller 46 for controlling the EGR valve 21b and the stationary blade rotating means lid by a rotation sensor 43 and a load sensor 44. The engine also has an intake quantity sensor 22, an intake pressure sensor 23, and an intake temperature sensor 24. The controller 46 has a target value setting means 46b for setting the target air quantity and the target supercharged pressure based on the detected output of each sensor and a deviation setting means 46c for setting the EGR valve deviation quantity and the VGT deviation quantity based on each detected output, target air quantity and target supercharged pressure. The controller controls the EGR valve by the proportional integral correction of the steady EGR opening based on the EGR valve deviation quantity, and controls the stationary blade rotating means by the proportional integral correction of the steady target VGT opening based on the VGT deviation quantity.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine having a variable-blade type turbocharger, in which part of exhaust gas is recirculated to an intake passage or a cylinder and recirculated. It concerns the device. 2. Description of the Related Art Conventionally, there is known an EGR device having an EGR passage for recirculating exhaust gas of a diesel engine into an intake passage and an EGR valve provided in the EGR passage for adjusting the recirculation amount of the exhaust gas. Have been. In this EGR device, the deviation between the target excess air ratio and the actual excess air ratio of the exhaust gas is reduced in order to reduce particulate components and NOx components such as black smoke and unburned fuel contained in the exhaust of the diesel engine. The control of the EGR valve is performed. That is, a target excess air ratio corresponding to an operating state of the engine detected by an engine rotation sensor and a load sensor is set, and exhaust gas flowing through the exhaust passage is detected by a linear air-fuel ratio sensor provided in the exhaust passage. The actual excess air ratio of the gas is detected, and when the actual excess air ratio becomes larger than the target excess air ratio, the actual excess air ratio is reduced by opening the EGR valve and increasing the exhaust gas recirculation amount. When the actual excess air ratio becomes smaller than the target excess air ratio, the EGR valve is closed to reduce or cut the amount of exhaust gas recirculation, thereby executing control to increase the actual excess air ratio, thereby causing excessive exhaust gas recirculation. It is possible to reduce the NOx component in the exhaust gas without generating black smoke due to the above. However, the linear air-fuel ratio sensor is expensive and has a delay in detection. For example,
The detection response time constant of the sensor is on the order of 1/10 to several seconds. For this reason, the correction of the fuel injection pressure is delayed in the initial stage of acceleration or in the early stage of shifting when the target excess air ratio and the actual excess air ratio are most shifted. In other words, although the correction amount of the fuel injection pressure must be given in accordance with the response delay timing of the actual excess air ratio, when the error of the actual excess air ratio from the target excess air ratio is the largest due to the detection delay of the sensor, If the fuel injection pressure does not change and the error in the actual excess air ratio decreases, the fuel injection pressure will change, causing black smoke to occur and knocking noise to the diesel engine. is there. When the engine is equipped with a variable-blade type turbocharger, the control of the variable blade and the control of the EGR valve are independently performed by a map assuming a steady operating state. Therefore, a change in the actual exhaust gas recirculation amount due to a response delay of the actual supercharging pressure greatly affects a so-called turbo lag at the time of acceleration or a shift, thereby causing an error between the actual excess air ratio and the target excess air ratio and an error between the actual EGR ratio and the target EGR ratio. The error further increased, and the particulate components in the exhaust gas and N
The actual excess air ratio and the actual EG are added to the target excess air ratio and the EGR ratio set to values that can appropriately reduce both the Ox component and the Ox component.
There is a problem that it is difficult to make the R rates equal. SUMMARY OF THE INVENTION It is an object of the present invention to appropriately control an EGR valve and a stationary blade rotating means while performing a calculation with good response even during a transient operation of an engine so that black smoke, particulate components and NOx contained in exhaust gas are controlled. An object of the present invention is to provide an exhaust gas recirculation device for an engine capable of sufficiently reducing components. Means for Solving the Problems The invention according to claim 1 is:
As shown in FIGS. 1 and 2, a turbocharger 11 having stationary blade rotating means 11d and an E having an EGR valve 21b are provided.
The EGR valve 21b and the EGR valve 21b according to the steady-state EGR opening and the steady-state VGT opening that are determined based on each detection output of the GR device 21, a rotation sensor 43 that detects the rotation speed of the engine 12, and a load sensor 44 that detects the load of the engine 12. Controller 4 for controlling stationary blade rotating means 11d
6 is an improvement of the exhaust gas recirculation system for the engine provided with the above. The characteristic configuration includes an intake air amount sensor 22 for detecting an intake air flow rate in the intake passage 17 of the engine 12, an intake pressure sensor 23 for detecting intake pressure, and an intake temperature sensor 24 for detecting intake temperature. , Rotation sensor 43, load sensor 44, intake air amount sensor 22, and intake air temperature sensor 24.
And target value setting means 46b for setting the target air amount and the target supercharging pressure based on the respective detected outputs of the intake air amount sensor 22, the intake air pressure sensor 23, and the target air amount and the target supercharging pressure. EGR valve deviation amount and V
A deviation value setting means 46c for setting each GT deviation amount is provided in the controller 46.
The EGR valve 21b is operated in accordance with a target EGR opening obtained by proportionally integrating the steady EGR opening based on the EGR valve deviation amount.
And the stationary blade rotating means 11d is configured to cooperately control the stationary blade rotating means 11d in accordance with the target VGT opening obtained by correcting the steady-state target VGT opening by proportional integration based on the VGT deviation amount. In the exhaust gas recirculation system for an engine according to the present invention, the relatively inexpensive intake air amount sensor 22, intake pressure sensor 23, and intake air temperature sensor 24 are used instead of the conventionally used linear air-fuel ratio sensor. Is used, it can be inexpensive as compared with the conventional apparatus. Further, the intake air amount sensor 22, the intake pressure sensor 23, and the intake air temperature sensor 24 are provided in the intake passage of the engine 12, and are controlled by the controller 46 based on the detection outputs of these sensors. Compared to the case where the controller controls the output based on the detection output of the provided linear air-fuel ratio sensor, the responsiveness to a change in the environment in which the engine 12 can operate, the initial stage of acceleration, and the initial stage of shifting can be improved. Further, the deviation value setting means 46c of the controller 46 detects the EGR valve deviation based on the mutual relationship between the value of each detection output of the intake air amount sensor 22 and the intake air pressure sensor 23 and the difference between the target air amount and the target supercharging pressure. Since the controller 46 sets the variable blade amount and the VGT deviation amount, and the controller 46 performs control of the variable blade in the turbocharger 11 and control of the EGR valve 21b in a coordinated manner, control of the variable blade and control of the EGR valve are independent of each other. The EGR valve 21b and the stationary blade rotating means 11d can be appropriately controlled, respectively, as compared with the conventional control performed according to the set map. Next, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a diesel engine 12 provided with a variable-wing type turbocharger 11. An intake pipe 15b is connected to an intake port 14 of the engine 12 via an intake passage 15, that is, an intake manifold 15a.
An exhaust pipe 17b is connected to the exhaust port 16 via an exhaust passage 17, that is, an exhaust manifold 17a. The turbocharger 11 is provided in the intake pipe 15b and rotatably accommodates a compressor impeller (not shown), and the turbocharger 11 is provided in the exhaust pipe 17b and rotatably accommodates a turbine impeller (not shown). And a turbine housing 11b. The turbine housing 11b and the compressor housing 11a are connected by a connecting portion 11c that rotatably holds the center of a shaft (not shown),
The turbine impeller and the compressor impeller are respectively fitted to both ends of the shaft. On the other hand, stationary blade rotating means 11d operated by a multi-stage air cylinder or a servomotor is mounted on the outer surface of the turbine housing 11b, and is rotated inside the turbine housing 11b by the stationary blade rotating means 11d. A stationary blade (not shown) that can change the nozzle area is provided. That is, the turbocharger 11 is configured such that the turbine efficiency can be controlled by making the angle of a variable vane (not shown) variable by the vane rotating means 11d.
(Variable Geometry Turbo). An intercooler 19 for cooling intake air is provided in an intake pipe 15b between the compressor housing 11a and the intake manifold 15a. The engine 12 has an exhaust manifold 17.
An EGR device 21 is provided that recirculates a part of the exhaust gas in a through the EGR pipe 21a to the intake manifold 15a. The EGR device 21 includes an EGR pipe 21a having one end connected to the exhaust manifold 17a, bypassing the engine 12, and having the other end connected to the intake manifold 15a;
An EGR valve 21b provided on the GR pipe 21a and capable of adjusting the flow rate of exhaust gas returned from the exhaust manifold 17a through the EGR pipe 21a to the intake manifold 15a.
And Although not shown, the EGR valve 21b drives the valve body by an actuator to adjust the opening degree of the valve body. Note that an air-driven valve or the like may be used instead of the electric valve as the EGR valve. The EGR pipe 21a is provided with an EGR cooler 21c for cooling exhaust gas (EGR gas) recirculated to the intake manifold 15a. The engine 12 is provided with a rotation sensor 43 for detecting the rotation speed of the crankshaft and a load sensor 44 for detecting the amount of depression of the accelerator pedal, that is, for detecting the load on the engine 12. The detection outputs of the rotation sensor 43 and the load sensor 44 are connected to the control input of the controller 46, and the control output of the controller 46 is connected to the EGR valve 21b and the stationary blade rotating means 11d, respectively. The controller 46 is provided with a memory 46a. The memory 46a stores a steady-state EGR opening degree and a steady-state VGT opening degree determined based on the rotation speed and the load of the engine 12 in a steady operation state of the engine 12, as a map. The target excess air ratio and the target EGR ratio according to the operation state are also stored as a map. The intake pipe 15b upstream of the compressor housing 11a is provided with an intake air quantity sensor 22 for detecting the flow rate of intake air to the intake manifold 15a, and the intake pipe 15b downstream of the compressor housing 11a is provided with an intake manifold 15a. An intake pressure sensor 23 for detecting an internal intake pressure is provided. And the intake manifold 15a
Is provided with an intake air temperature sensor 24 for detecting the intake air temperature inside the intake manifold 15a. Intake air amount sensor 22
The detection outputs of the intake pressure sensor 23 and the intake temperature sensor 24 are connected to control inputs of a controller 46. The controller 46 includes target value setting means 46b for setting a target air amount and a target supercharging pressure based on the respective detection outputs of the rotation sensor 43, the load sensor 44, the intake air amount sensor 22, and the intake air temperature sensor 24; A deviation value setting means 46c for setting an EGR valve deviation amount and a VGT deviation amount based on the target air amount and the target supercharging pressure based on the respective detection outputs of the sensor 22 and the intake pressure sensor 23 is provided. The operation of the thus configured exhaust gas recirculation apparatus will be described. As shown in FIG. 2, when the engine 12 is operating, the controller 46 takes in each detection output of the rotation sensor 43 and the load sensor 44, and in the operation state stored separately in the memory 46 a based on each detection output. A specific steady EGR opening and a steady VGT opening are determined in comparison with the map. On the other hand, a target value setting means 46b of the controller 46 sets a target air amount and a target supercharging pressure based on the respective detection outputs of the rotation sensor 43, the load sensor 44, the intake air amount sensor 22, and the intake air temperature sensor 24. I do. More specifically, the target value setting means 46b determines the target excess air ratio and the target EGR ratio according to the operation state from the map stored in the memory 46a based on the detection outputs of the rotation sensor 43 and the load sensor 44. Then, the target air amount and the target supercharging pressure are set from the following equations and the equations based on the values and the detection outputs of the respective sensors. Target air amount = Target excess air rate × Fuel injection amount ································································································································· Constant × value of intake air temperature sensor / (cylinder volume × engine volumetric efficiency) ... Next, the deviation value setting means 46c of the controller 46 calculates the above equation from the values of the respective detection outputs of the intake air amount sensor 22 and the intake pressure sensor 23. The difference between the target air amount and the target supercharging pressure obtained by the equation is obtained, and the difference is multiplied by a constant determined based on each detection output of the rotation sensor 43 and the load sensor 44 by a determinant to obtain the EGR valve deviation amount. And the amount of VGT deviation are set. That is, the deviation value setting means sets the EGR valve deviation amount and the VGT deviation amount based on the following equation and the equation given by the determinant. EGR valve deviation amount = K11 × (intake air amount sensor value−target air amount) + K12 × (intake air pressure sensor value−target supercharging pressure) VGT deviation amount = K21 × (intake air amount sensor value) −target air amount) + K22 × (value of intake pressure sensor−target supercharging pressure) where K11, K12, K21 and K22 are rotation sensors 43
And a constant determined based on each detection output of the load sensor 44. The constant fluctuates depending on the operating condition of the engine 12.
Is stored. The controller 46 performs a proportional-integral correction on a preset steady-state EGR opening based on the EGR valve deviation obtained by the deviation setting means.
The EGR valve 21b is controlled in accordance with the GR opening, and the stationary blade rotating means 11 is controlled in accordance with the target VGT opening in which the steady-state target VGT opening is proportionally integrated corrected based on the VGT deviation amount.
control d. In this exhaust gas recirculation system for an engine, a relatively inexpensive intake air amount sensor 22, intake pressure sensor 23, and intake air temperature sensor 24 are used in place of the conventionally used linear air-fuel ratio sensor. It can be cheaper than that of In addition, these intake air amount sensors 2
2, an intake pressure sensor 23, and an intake temperature sensor 24 are provided on the intake side of the engine 12, respectively, and are controlled by the controller 46 based on the detection outputs of these sensors. , Engine 1
The responsiveness to changes in the environment in which the vehicle 2 can operate, initial acceleration and initial shifting can be improved. Further, the deviation value setting means 46c of the controller 46 detects an EGR valve deviation based on the mutual relation between the value of each detection output of the intake air amount sensor 22 and the intake air pressure sensor 23 and the difference between the target air amount and the target supercharging pressure. Since the controller 46 sets the variable blade amount and the VGT deviation amount, and the controller 46 performs the control of the variable blade in the turbocharger 11 and the control of the EGR valve 21b in a coordinated manner, the control of the variable blade and the control of the EGR valve are independently performed. EG compared to the conventional control
The R valve 21b and the stationary blade rotating means 11d can be appropriately controlled. As a result, the engine 12
Irrespective of whether it is in the initial stage of acceleration or the initial stage of shifting, it is possible to recirculate the optimal amount of exhaust gas into the intake passage while securing the optimal amount of intake according to the operating condition. Particulate components such as black smoke and unburned fuel and NOx components contained in the exhaust gas can be sufficiently reduced. As described above, according to the present invention, an intake air amount sensor for detecting an intake air flow rate in an intake passage of an engine is used instead of a conventionally used relatively expensive linear air-fuel ratio sensor. And an intake air pressure sensor for detecting the intake air pressure and an intake air temperature sensor for detecting the intake air temperature. Further, since the intake air amount sensor, the intake air pressure sensor, and the intake air temperature sensor are provided on the intake side of the engine and are controlled by the controller based on the detection outputs of these sensors, a conventional linear air-fuel ratio sensor is used. As compared with the case, the responsiveness to a change in the environment in which the engine can operate, the initial stage of acceleration, and the initial stage of shifting can be improved. Further, target value setting means for setting a target air amount and a target supercharging pressure based on each detection output from each sensor, and based on each detection output, the target air amount and the target supercharging pressure of the sensors. EGR valve deviation and VG
The controller is provided with a deviation value setting means for setting each of the T deviation amounts, and the controller controls the EGR valve in accordance with the target EGR opening obtained by proportionally integrating the steady-state EGR opening based on the EGR valve deviation and controls the VGT deviation. VG obtained by correcting the steady-state target VGT opening by proportional integral based on the
Since the configuration is such that the stationary blade rotating means is controlled in accordance with the T opening, the controller performs control of the variable blade and control of the EGR valve in the turbocharger in coordination, and thus control of the variable blade and control of the EGR valve. The EGR valve and the stationary blade rotating means can be appropriately controlled, respectively, as compared with the conventional control in which the control is independently performed.
As a result, it is possible to recirculate the optimal amount of exhaust gas into the intake passage while securing the optimal amount of intake according to the operating state of the engine regardless of whether the engine is in the initial stage of acceleration or the initial stage of shifting. Particulate components such as black smoke and unburned fuel and NOx components contained in the exhaust gas of the diesel engine can be sufficiently reduced.

[Brief description of the drawings] FIG. 1 is a configuration diagram showing an exhaust gas recirculation device of the present invention. FIG. 2 is a system diagram showing control of the controller. [Explanation of symbols] 11 Turbocharger 11d Stator blade rotating means 12 Engine 15 Intake passage 15a intake manifold 17 Exhaust passage 21 EGR device 21a EGR passage 21b EGR valve 22 Intake volume sensor 23 Intake pressure sensor 24 Intake air temperature sensor 43 Rotation sensor 44 Load sensor 46 Controller 46b Target value setting means 46c deviation value setting means

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02D 21/08 301 F02D 23/00 K 23/00 41/18 F 41/18 43/00 301N 43/00 301 301R F02B 37/12 301Q F term (reference) 3G005 DA02 EA15 FA04 FA35 GA04 GB25 GD01 JA02 JA13 JA23 JA24 JA39 JA42 JA45 3G062 AA01 AA05 BA02 CA04 CA09 DA02 EA04 EA10 EB06 ED08 FA04 FA05 FA08 FA13 GA01 GA02 GA04 GA06 BA09 GA08 BA08 CA04 DA05 DA10 DA12 EB08 EB12 EC04 FA02 FA07 FA10 FA12 FA33 3G092 AA02 AA17 AA18 BA02 BA04 DB03 DC09 EA01 EA02 EA08 EA09 EB03 EC06 EC09 FA17 FA18 FA24 GA12 GB09 HA01Z HA04Z HA05Z HA06Z HA16XHA13 HA13X3 KB10 LC03 LC06 NA04 NA07 NA09 NC02 ND03 NE06 NE20 PA01Z PA07Z PA10Z PA11Z PA16Z PD15A PE01Z

Claims (1)

Claims 1. A turbocharger (11) having a stationary blade rotating means (11d) and an EGR device (21) having an EGR valve (21b).
A rotation sensor for detecting a rotation speed of the engine (12)
(43) and a load sensor (4
4) a controller (46) for controlling the EGR valve (21b) and the stationary blade rotating means (11d) in accordance with the steady EGR opening and the steady VGT opening determined based on the respective detection outputs. In the exhaust gas recirculation device, an intake air amount sensor (2
2), an intake pressure sensor (23) for detecting intake pressure, and an intake temperature sensor (24) for detecting intake temperature, wherein the rotation sensor (43), the load sensor (44), and the intake amount sensor. (22) and target value setting means (46b) for setting a target air amount and a target supercharging pressure based on the respective detection outputs of the intake air temperature sensor (24), the intake air amount sensor (22) and the intake air sensor. The EGR valve deviation amount and V are determined based on each detection output of the air pressure sensor (23), the target air amount, and the target supercharging pressure.
A deviation value setting means (46c) for setting a GT deviation amount is provided in the controller (46). The controller (46) corrects the steady-state EGR opening proportionally and integrally based on the EGR valve deviation amount. Target EG
The stationary blade rotating means (1) is controlled in accordance with a target VGT opening obtained by controlling the EGR valve (21b) according to the R opening and correcting the steady-state target VGT opening by proportional integral integration based on the VGT deviation amount.
An exhaust gas recirculation device for an engine, which is configured to control 1d) in a coordinated manner.