JP2019044601A - Method for detecting turbo response lag - Google Patents

Abstract

To provide a method for detecting a turbo response lag, by which a response lag of a turbocharger can be detected even in the case where a position sensor is not provided.SOLUTION: There are provided: a turbocharger 2 including nozzle vanes 22 that control a flow rate of exhaust gas flowing in an exhaust gas turbine 21; an actuator 51 that controls the opening of the nozzle vanes 22 by the control pressure of compressed air supplied from an air tank 53; a solenoid valve 52 that adjusts the control pressure of compressed air supplied to the actuator 51; target position setting means for setting a target operation position X of the actuator 51 according to the rotation speed of an engine 1 and a load thereon; and a boost pressure sensor 33 that detects a boost pressure P of the engine 1. A method for detecting a turbo response lag, comprises detecting a response lag of the turbocharger 2 on the basis of a change of the boost pressure P at the time when the control pressure is changed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a detection method for detecting response delay of a variable nozzle vane type turbocharger.

  One of the engine power-up technologies is a turbocharger. This type of turbocharger utilizes the exhaust of the engine to drive the supercharger to compress the intake air, thereby enhancing the efficiency of charging the intake air to the engine. For example, Patent Document 1 discloses a variable nozzle vane type turbocharger, so-called VG turbo (VG :), which improves the turbo efficiency by adjusting the flow path of the exhaust with respect to the engine speed to control the driving amount of the turbocharger. Variable Geometry) is disclosed.

  More specifically, the VG turbo disclosed in Patent Document 1 is an annular ring provided with the angles (opening degrees) of the nozzle vanes arranged at equal intervals around the turbine blade of the exhaust turbine provided in the turbocharger. It is variable by adjusting the rotational position of the engine, thereby controlling the speed (flow rate) of the exhaust gas from the engine flowing into the exhaust turbine. The adjustment of the rotational position of the annular ring is carried out by driving an actuator comprising, for example, an air cylinder provided with a rod connected to the annular ring. Here, the actual operating position of the actuator described above is detected by a position sensor provided in the turbocharger, and is feedback-controlled to be within a tolerance range for the target operating position.

Patent No. 3514606

  By the way, when a failure occurs in the control mechanism that controls the opening of the nozzle vane as described above, the actual operating position of the rod may not reach the target operating position, or it may take longer than expected to reach the target operating position. Therefore, it is necessary to detect such a change as the response delay of the turbocharger. However, among the above-mentioned VG turbos, there is a type of turbocharger that displaces the rod by feed forward control based on the correspondence between the control amount of the actuator and the opening degree of the nozzle vane without providing a position sensor. . Therefore, in the VG turbo without the position sensor, the actual operating position of the actuator can not be specified, and there is a possibility that the response delay of the turbocharger can not be detected. Further, when a position sensor is newly added to the VG turbo, in addition to the cost of the position sensor, the manufacturing cost may be increased due to the design change of the VG turbo itself.

  The present invention has been made in view of such a situation, and an object of the present invention is to detect a turbo response delay which can detect a response delay of a turbocharger even when the position sensor is not provided. To provide a way.

  In order to achieve the above object, the method for detecting response delay of a turbocharger according to the present invention comprises: a turbocharger including a nozzle vane for controlling the flow rate of exhaust gas flowing into an exhaust turbine; and control pressure of compressed air supplied from an air tank. An actuator for controlling the opening degree of the nozzle vanes, a solenoid valve for adjusting the control pressure of the compressed air supplied to the actuator, and a target for setting a target operating position of the actuator according to the number of rotations and load of the engine Position setting means and boost pressure detection means for detecting a boost pressure of the engine are provided, and the response delay of the turbocharger is detected based on a change in the boost pressure when the control pressure is changed.

  When the target position setting means sets the target operating position of the actuator, the solenoid valve adjusts the control pressure of the compressed air supplied from the air tank to the actuator. At this time, the actuator controls the flow rate of the exhaust gas flowing into the exhaust turbine of the turbocharger by controlling the opening degree of the nozzle vanes. Thereby, the turbocharger can improve turbo efficiency through control of the number of revolutions of the exhaust turbine. Here, when the rotation speed of the turbocharger changes, it is possible to detect that the boost pressure of the air supplied to the engine has changed by the boost pressure detection means. Therefore, the response delay of the turbocharger can be detected based on the speed of change of the boost pressure when the control pressure to the solenoid valve is changed. Therefore, according to the response delay detection method according to the present invention, even if the position sensor is not provided, the response delay of the turbocharger can be detected.

  According to the present invention, it is possible to provide a turbo response delay detection method capable of detecting the response delay of the turbocharger even when the position sensor is not provided.

It is a block diagram which shows the engine periphery mechanism of a vehicle. It is a timing chart which shows a turbo response typically.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described below, and can be arbitrarily changed and implemented without changing the gist of the present invention. Further, the drawings used for describing the embodiments all schematically show constituent members, and in order to deepen understanding, partial emphasis, enlargement, reduction, or omission, etc. are performed. There are cases where the scale, shape, etc. are not accurately represented.

  FIG. 1 is a configuration diagram showing an engine peripheral mechanism of a vehicle, and is a system configuration diagram showing an engine 1 mounted on the vehicle and a configuration related to intake and exhaust thereof. The present system includes an engine 1, a turbocharger 2, an intake path 3, an exhaust path 4, a VG control mechanism 5, and an engine ECU 6.

  The engine 1 is a four-cylinder diesel engine in the present embodiment, and includes a common rail 11, an injector 12, an intake manifold 13, an exhaust manifold 14, an EGR passage 15, and an EGR valve 16.

  The common rail 11 is a high pressure accumulation chamber common to the cylinders, and temporarily stores light oil as high pressure fuel supplied from a fuel injection pump (not shown). The injectors 12 inject the high pressure fuel stored in the common rail 11 into the respective cylinders. The intake manifold 13 is a pipe for feeding air to the inside of the engine 1 and distributes the air in the four cylinders. The exhaust manifold 14 is a pipe for delivering air to the outside of the engine 1 and collects the air in the four cylinders. The EGR passage 15 is a passage of air communicating the intake manifold 13 and the exhaust manifold 14 with each other. The EGR passage 15 carries out exhaust gas recirculation (Exhaust Gas Recirculation) by sending out a part of the air sent from the exhaust manifold 14 to the intake manifold 13, thereby reducing nitrogen oxides contained in the exhaust gas and improving fuel efficiency. Provided. The EGR valve 16 is a valve mechanism that adjusts the amount of air sent from the exhaust manifold 14 to the intake manifold 13 and prevents backflow of air.

  The turbocharger 2 includes an intake turbine 20, an exhaust turbine 21, and a nozzle vane 22.

  The intake turbine 20 is a windmill provided in the middle of an intake path 3 for feeding air to the engine 1, and rotates at high speed to compress introduced air and supply it to the engine 1. The exhaust turbine 21 is an impeller that rotates at a high speed by the flow of the exhaust gas delivered from the exhaust manifold 14 and generates rotational torque in the intake turbine 20 having a common rotational axis. That is, the intake turbine 20 is rotated by the power of the exhaust turbine 21 generated by the exhaust gas to increase the air fed to the engine 1. The nozzle vanes 22 are disposed around a turbine blade (not shown) of the exhaust turbine 21 and control the flow rate of the exhaust gas flowing in from the exhaust manifold 14 by changing the flow path of the exhaust gas by adjusting the opening degree. Here, the nozzle vanes 22 are connected to a rod 50 described later, and the degree of opening is controlled by the displacement of the rod 50.

  The intake path 3 is a flow path of air taken in from the outside air and supplied to the engine 1, and includes an air filter 30, an air flow sensor 31, an intercooler 32, and a boost pressure sensor 33 as "boost pressure detection means" .

  The air filter 30 is a filter that purifies the air fed into the engine 1 by removing impurities such as dust and dirt from the air taken into the intake path 3 from the outside air. The air flow sensor 31 is a sensor that measures the flow rate of air fed into the engine 1. The intercooler 32 cools the air whose temperature has risen by being rapidly compressed in the intake turbine 20, and suppresses the density decrease of the air fed into the engine 1. The boost pressure sensor 33 is a sensor that measures the pressure of air supplied to the intake manifold 13, that is, the boost pressure.

  The exhaust path 4 is a flow path that purifies exhaust gas discharged by the engine 1 and discharges it to the outside air, and includes an exhaust throttle valve 40, an exhaust post-treatment unit 41, and a muffler (not shown).

  The exhaust throttle valve 40 is a valve mechanism for controlling the exhaust flow rate of the exhaust gas sent from the exhaust manifold 14 via the exhaust turbine 21. The exhaust post-treatment unit 41 contains an oxidation catalyst and a DPF (Diesel Particulate Filter: diesel particulate filter), and purifies the exhaust gas by collecting PM (Particulate Matter) contained in the exhaust gas. The exhaust gas that has passed through the exhaust post-treatment unit 41 is reduced in noise by a muffler (not shown) and discharged to the outside of the vehicle.

  The VG control mechanism 5 is a mechanism that controls the opening degree of the nozzle vanes 22 in the turbocharger 2 and includes a rod 50, an actuator 51, a solenoid valve 52, and an air tank 53.

  The rod 50 is a member that has one end connected to the nozzle vane 22 and controls the opening degree of the nozzle vane 22 by being displaced in the length direction. The actuator 51 is a power conversion mechanism that is connected to the other end of the rod 50 and displaces the rod 50 according to the control pressure of the compressed air by being supplied with the compressed air. The solenoid valve 52 is a valve mechanism that adjusts the control pressure of the compressed air supplied to the actuator 51 based on a control signal from the engine ECU 6. The air tank 53 is a supply source of compressed air for driving the actuator 51. That is, the VG control mechanism 5 receives a control signal related to the target operating position of the actuator 51 from the engine ECU 6, and the solenoid valve 52 adjusts compressed air to a control pressure corresponding to the target operating position to drive the actuator 51. Thus, the rod 50 is displaced to control the opening degree of the nozzle vanes 22.

  The engine ECU 6 (Electronic Control Unit) is a control device that includes a CPU, a memory, a timer counter, etc., and performs drive control of the entire system related to the engine 1 and the engine peripheral mechanism. The engine ECU 6 is connected to the injector 12, the EGR valve 16, the exhaust throttle valve 40, and the solenoid valve 52 in each cylinder of the engine 1 to control these respective devices.

  Further, the engine ECU 6 performs various controls of the vehicle as described above, and acquires various sensor information mounted in the system related to the engine 1 and the engine peripheral mechanism. For example, the engine ECU 6 obtains measurement values from various sensors (not shown) for measuring the number of rotations of the engine 1, the fuel injection amount, and the number of rotations of the turbocharger 2 in addition to the air flow sensor 31 and boost pressure sensor 33. The control of the engine 1 is optimized based on the measured value. Specifically, engine ECU 6 sets target operation position X of actuator 51 to control the drive amount of turbocharger 2 in accordance with the number of revolutions of engine 1 and the required load, and solenoid valve 52 as a control signal. (Target position setting means).

  Next, a method of detecting the response delay of the turbocharger 2 will be described. FIG. 2 is a timing chart schematically showing a turbo response. More specifically, FIG. 2A is a control signal output from the engine ECU 6 to the solenoid valve 52, and shows the change of the target operating position X of the actuator 51. As shown in FIG. Further, FIG. 2B shows the measurement value of the boost pressure sensor 33 with respect to the change of the target operating position X, that is, the temporal change of the boost pressure P of the air supplied to the engine 1.

  The engine ECU 6 controls the drive amount of the turbocharger 2 by changing the control signal output to the solenoid valve 52. Here, as shown in FIG. 2A, the engine ECU 6 changes the target operating position X of the actuator 51 from X1 to X2 at time t1 to limit the flow rate of the exhaust gas passing through the exhaust turbine 21.

  When the control signal input to the solenoid valve 52 changes at time t1, the control pressure of the air supplied from the air tank 53 to the actuator 51 rises, and the actuator 51 is displaced toward X2. As a result, the opening degree of the nozzle vanes 22 is limited via the rod 50, the rotational speed of the turbocharger 2 is increased, and the flow rate of air supplied to the engine 1 is increased. Therefore, when the turbo response is normal, the boost pressure P starts to increase at time t2 after a predetermined time from time t1, as shown as pressure P1 in FIG. 2 (B). Then, the boost pressure P exceeds the pressure threshold th set in advance relatively quickly at time t3.

  On the other hand, when an abnormality occurs in the turbo response, as shown by the pressure P2 in FIG. 2B, the increase speed of the boost pressure P is slow, and the time until the time t4 is exceeded until the pressure threshold th is exceeded. It will be necessary. Further, when the turbocharger 2 or the VG control mechanism 5 fails due to a failure, the boost pressure P does not exceed the pressure threshold th as shown as the pressure P3 in FIG. 2 (B).

  As described above, the engine ECU 6 delays the turbo response by counting the elapsed time required until the boost pressure P reaches the pressure threshold th based on the time when the control signal is output to the solenoid valve 52. It can be detected whether or not it is present. Therefore, according to the response delay detection method of the present invention, even if the turbocharger 2 does not have a position sensor, the response delay of the turbocharger 2 can be detected.

  This is the end of the description of the embodiment, but the present invention is not limited to the above embodiment. For example, in the above embodiment, although the method for detecting the response delay of the turbocharger 2 by the change of the boost pressure P has been exemplified, the turbo is also detected by the same method according to the air flow rate measured by the air flow sensor 31 shown in FIG. The response delay of the charger 2 can be detected. Further, the measurement values of the boost pressure sensor 33 and the air flow sensor 31 may be combined to detect the response delay of the turbocharger 2.

1 Engine 2 Turbocharger 21 Exhaust Turbine 22 Nozzle Vane 33 Boost Pressure Sensor 51 Actuator 52 Solenoid Valve 53 Air Tank

Claims (1)

A turbocharger including nozzle vanes for controlling the flow rate of exhaust gas flowing into the exhaust turbine;
An actuator for controlling an opening degree of the nozzle vane by a control pressure of compressed air supplied from an air tank;
A solenoid valve for adjusting the control pressure of the compressed air supplied to the actuator;
Target position setting means for setting a target operating position of the actuator according to the number of revolutions and load of the engine;
Boost pressure detecting means for detecting a boost pressure of the engine;
A method for detecting a response delay of a turbocharger, which detects a response delay of the turbocharger based on a change in the boost pressure when the control pressure is changed.

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