JP4492336B2 - Turbocharger control method - Google Patents

Description

  The present invention relates to a method for controlling a turbocharger for a vehicle, and more particularly to a method for controlling a geometry of a diffuser provided in a compressor.

  As a turbocharger for a vehicle, in order to increase the supercharging pressure in a low engine speed range, a turbocharger having a variable guide vane of variable geometry on the inlet side of the compressor (see, for example, Patent Document 1), 2. Description of the Related Art Conventionally, a turbocharger having a variable geometry variable diffuser body on the outlet side (see, for example, Patent Document 2) is generally known.

  Here, in the turbocharger described in Patent Document 1, the variable guide vane disposed on the inlet side of the compressor is configured so that the intake air is pre-swirled so as to increase the supercharging pressure in the low engine speed range of the compressor. It flows into the impeller.

On the other hand, in the turbocharger described in Patent Document 2, the variable diffuser body arranged on the outlet side of the compressor is connected to the variable nozzle body arranged on the inlet side of the turbine and is rotatable.
Japanese Patent Laid-Open No. 11-82036 (paragraph number 31, FIG. 2) JP 2001-115848 A (Abstract, FIG. 1)

  By the way, in the turbocharger described in Patent Document 1 or 2, when the geometry of the variable guide vane or the variable diffuser body is changed, the air flow rate and the supercharging pressure of the compressor rapidly change, and the engine torque of the vehicle May fluctuate significantly.

  Accordingly, an object of the present invention is to provide a turbocharger control method capable of suppressing fluctuations in engine torque when changing the geometry of the diffuser.

  A turbocharger control method according to the present invention is a turbocharger control method for a vehicle in which a compressor has a variable geometry diffuser. When changing the geometry of the variable diffuser, conditions that are the same before and after the change of the compressor geometry It is characterized by changing the geometry based on this.

  In the turbocharger control method according to the present invention, since the rotation speed, air flow rate, and pressure ratio of the compressor match before and after the change of the variable diffuser geometry, fluctuations in the engine torque when the variable diffuser geometry is changed are suppressed. The

  According to the turbocharger control method of the present invention, the rotation speed of the compressor, the air flow rate, and the pressure ratio match before and after the change of the variable diffuser geometry. Can be suppressed.

  Embodiments of a turbocharger control method according to the present invention will be described below with reference to the drawings. 1 is a cross-sectional view showing a schematic configuration of a turbocharger to which a turbocharger control method according to an embodiment is applied, and FIG. 2 is a front view of a base plate showing a fully open state of a variable diffuser shown in FIG. 3 is a front view of the base plate showing a fully closed state of the variable diffuser shown in FIG. 1, and FIG. 4 is a rear view of the base plate shown in FIG.

  A turbocharger control method according to an embodiment is applied to a turbocharger 1 having a structure as shown in FIG. The turbocharger 1 includes a turbine housing 2 interposed in the middle of an exhaust system of a vehicle engine (not shown), a compressor housing 3 interposed in the middle of an intake system, and a center housing (bearing housing) that connects the two. 4 is provided.

  A turbine wheel 5 that is rotationally driven by exhaust gas flowing through the exhaust system is accommodated in the turbine housing 2, and a compressor impeller 6 that supercharges the intake system air by pressurizing it to atmospheric pressure or higher is contained in the compressor housing 3. Contained. The turbine wheel 5 and the compressor impeller 6 are connected via a shaft 7 so as to rotate integrally. The shaft 7 is rotatably supported by the center housing 4 via a floating bearing (not shown).

  Here, in order to increase the supercharging pressure in the low engine speed range, the air flow from the compressor outlet side, that is, from the outer periphery of the base end of the compressor impeller 6 to the scroll flow path 3A in the compressor housing 3 is increased. As the variable geometry diffuser, a plurality of variable diffusers 8 having a cross-sectional shape formed in an airfoil shape are arranged. Each variable diffuser 8 is disposed on the front side of a base plate 9 having a donut disk shape fixed to the center housing 4 side in the compressor housing 3 as a support member.

  As shown in FIG. 2 and FIG. 3, the base plate 9 has a plurality of pivot shafts 10 that pass through the base plate 9 and are rotatable. And the pointed edge vicinity of each variable diffuser 8 is being fixed to the one end part of each rotation spindle 10 which protrudes in the front side of the baseplate 9. As shown in FIG.

  As shown in FIG. 4, the base end portion of the follower arm 11 for changing the blade angle of each variable diffuser 8 is fixed to the other end portion of each rotation support shaft 10 protruding to the back side of the base plate 9. Has been. Around these driven arms 11, unison rings 12 are arranged for simultaneously rotating the driven arms 11 to change the blade angles of the variable diffusers 8 at the same angle. .

  The unison ring 12 has an inner circumference guided by a plurality of guide rollers 13 attached to the back side of the base plate 9, and is supported so as to be rotatable concentrically with the base plate 9. A plurality of locking recesses 12A having a semicircular cross section are formed at equiangular intervals on the inner periphery of the unison ring 12, and the locking recesses 12A have a semicircular cross section of each driven arm 11. The formed tip portions are engaged with each other.

  The unison ring 12 is rotated by transmitting the rotational motion of a drive motor (not shown) attached to the compressor housing 3 (see FIG. 1) via the link mechanism 14, for example. The link mechanism 14 includes a rotation support shaft 14A that is rotatably supported by the base plate 9 and protrudes to the back side thereof, and a drive arm 14B having a base end fixed to the rotation support shaft 14A. Yes. The tip end of the drive arm 14B formed in a semicircular cross section is engaged with a semicircular cross section locking recess 12B formed in the inner periphery of the unison ring 12, and a drive motor (not shown) is properly connected. When rotating and reversing, the unison ring 12 is rotated in the direction of the arrow via the link mechanism 14 so that the blade angles of the variable diffusers 8 are simultaneously changed at the same angle.

  Here, in the turbocharger 1 shown in FIG. 1, the relationship between the flow rate of air flowing through the compressor housing 3 and the pressure ratio, which is the ratio of the outlet airflow pressure to the inlet airflow pressure of the compressor housing 3, is For example, as shown in the graph of FIG. 5, it changes according to the rotational speed of the compressor impeller 6 (compressor) and also changes according to the blade angle α which is the geometry of each variable diffuser 8.

  A characteristic line indicated by a dotted line in the graph of FIG. 5 indicates an initial state (blade angle α = 0 °) in which each variable diffuser 8 is slightly opened from the fully closed state (blade angle α = −13 °) as shown in FIG. 5 shows the relationship between the air flow rate and the pressure ratio with the number of revolutions of the compressor as a parameter, and the characteristic line shown by the solid line in the graph of FIG. 5 shows the blade angle of each variable diffuser 8 as shown in FIG. The relational characteristics in the fully opened state at α = 35 ° are shown with the rotation speed of the compressor as a parameter.

  As shown in FIG. 5, the surge line indicated by the dotted line at the blade angle α = 0 ° of each variable diffuser 8 exists on the side where the air flow rate is smaller than the surge line indicated by the solid line at the blade angle α = 35 °. Therefore, the characteristic is suitable for increasing the supercharging pressure in the low engine speed range. At each rotation speed of the compressor, the characteristic line of blade angle α = 0 ° indicated by a dotted line and the characteristic line of blade angle α = 35 ° indicated by a solid line intersect at a point indicated by a black circle. . That is, at this intersection point, the rotation speed of the compressor, the air flow rate, and the pressure ratio are the same.

  Therefore, in the turbocharger control method of one embodiment, as shown in the graph of FIG. 6, the line connecting the points indicated by black circles in FIG. 5 is used as a switching line, and the air flow rate and pressure ratio of the compressor are switched. , The blade angle α which is the geometry of each variable diffuser 8 is simultaneously changed between α = 0 ° and α = 35 °. In other words, when the region corresponding to the air flow rate and the pressure ratio of the compressor is in the closed region on the left side of the switching line, the blade angle α of each variable diffuser 8 is set to α = 0 °, When in the open region, the blade angle α is controlled so that the blade angle α of each variable diffuser 8 is α = 35 °.

  In order to realize such a control method, there is provided a geometry changing means for controlling the rotation of the drive motor described above to rotate the unison ring 12 by a predetermined angle in a desired direction.

  Further, as a sensor group for outputting a detection signal to the geometry changing means, an air flow sensor (thermal air mass flow sensor) for measuring the mass flow rate of air flowing in the compressor housing 3 shown in FIG. An inlet side air pressure sensor that measures the air pressure on the inlet side of the compressor housing 3, an outlet side air pressure sensor that measures the air pressure on the outlet side of the compressor housing 3, and an inlet side air temperature sensor that measures the air temperature on the inlet side of the compressor housing 3 Are attached to the compressor housing 3.

  As shown in FIG. 7, the above-described geometry changing means 20 receives detection signals from the above-described air flow sensor 21, inlet side air pressure sensor 22, outlet side air pressure sensor 23, and inlet side air temperature sensor 24, respectively. By outputting a predetermined drive signal based on the detection signal to the motor drive circuit 25, the rotation of the drive motor 26 is controlled.

  The geometry changing means 20 is configured using microcomputer hardware and software such as an ECU (Electric Control Unit) (not shown) mounted on the vehicle. This geometry changing means 20 includes an input / output interface I / O and A / D between the air flow sensor 21, the inlet side air pressure sensor 22, the outlet side air pressure sensor 23, the inlet side air temperature sensor 24, and the motor drive circuit 25. In addition to the converter, a ROM (Read Only Memory) that stores programs and data, a RAM (Random Access Memory) that temporarily stores input data, and a CPU (Central Processing Unit) that executes programs are provided as hardware.

  Here, the geometry changing means 20 includes a compressor pressure ratio calculating unit 20A, a geometry changing unit 20B, a data map 20C, and a drive signal output unit 20D as software. In the data map 20C, the switching lines shown in FIG. 6 are stored as a two-dimensional map.

  The compressor pressure ratio calculation unit 20A is configured to perform a temperature correction of the compressor pressure ratio (Pout / Pin) based on detection signals respectively input from the inlet side air pressure sensor 22, the outlet side air pressure sensor 23, and the inlet side air temperature sensor 24. ) And outputs a signal of the pressure ratio (Pout / Pin) to the geometry changing unit 20B.

  The geometry changing unit 20B generates a data map 20C based on the compressor pressure ratio (Pout / Pin) signal input from the compressor pressure ratio calculation unit 20A and the compressor air flow rate detection signal input from the airflow sensor 21. Lookup is performed to determine whether or not the region corresponding to the air flow rate and pressure ratio of the compressor is a closed region (α = 0 °) on the left side of the switching line in FIG. 6, and the determination signal is used as the drive signal output unit 20D. Output to.

  Based on the determination signal input from the geometry changing unit 20B, the drive signal output unit 20D is variable when the region corresponding to the air flow rate and pressure ratio of the compressor is a closed region on the left side of the switching line in FIG. A drive signal (α = 0 °) for setting the blade angle α of the diffuser 8 to α = 0 ° is output to the motor drive circuit 25, and the region corresponding to the air flow rate and pressure ratio of the compressor is shown in the switching line of FIG. In the case of the open region on the right side, a drive signal (α = 35 °) for setting the blade angle α of each variable diffuser 8 to α = 35 ° is output to the motor drive circuit 25.

  The motor drive circuit 25 is in a fully closed state in which the blade angle α of each variable diffuser 8 is α = 0 ° according to the input drive signal (α = 0 °) or drive signal (α = 35 °) (see FIG. 2). ) Or the rotation direction and the rotation amount of the drive motor 26 are controlled so as to be in the fully open state of α = 35 ° (see FIG. 3).

  With such a geometry changing means 20, the turbocharger control method of one embodiment is executed according to the processing procedure of the flowchart shown in FIG. First, with the operation of a vehicle engine (not shown), the detection signals of the inlet side air pressure sensor 22, the outlet side air pressure sensor 23, and the inlet side air temperature sensor 24 are respectively compressed by the compressor pressure ratio calculation unit 20A of the geometry changing means 20. (S1-S3).

  In the next step S4, the compressor pressure ratio calculation unit 20A calculates the pressure ratio (Pout / Pin) of the compressor whose temperature has been corrected, and a calculation signal for the pressure ratio (Pout / Pin) is input to the geometry change unit 20B. The In subsequent step S5, a detection signal of the air flow rate of the compressor is input from the air flow sensor 21 to the geometry changing unit 20B.

  Subsequently, the data of the data map 20C (see FIG. 6) is looked up by the geometry changing unit 20B (S6), and the region corresponding to the air flow rate and pressure ratio of the compressor input with the signal is on the left side of the switching line in FIG. It is determined whether or not it is a closed region (α = 0 °) (S7). The determination result is output from the geometry changing unit 20B to the drive signal output unit 20D.

  If the decision result in the step S7 is YES, a drive signal (α = 0 °) for setting the blade angle α of each variable diffuser 8 to α = 0 ° is sent from the drive signal output unit 20D to the motor drive circuit 25. (S8). On the other hand, if the decision result in the step S7 is NO, a drive signal (α = 35 °) for setting the blade angle α of each variable diffuser 8 to α = 35 ° is sent from the drive signal output unit 20D to the motor drive circuit 25. Is output (S8). As a result, the motor drive circuit 25 is driven so that the blade angle α of each variable diffuser 8 is in an initial state where α = 0 ° is slightly opened (see FIG. 2) or in a fully open state where α = 35 ° (see FIG. 3). The direction and amount of rotation of the motor 26 are controlled.

  According to the turbocharger control method of the embodiment, the air flow rate of the compressor is operated in the state where the turbocharger 1 is operated in accordance with the operation of the vehicle engine (not shown) by the series of processing procedures by the geometry changing unit 20. When the region corresponding to the pressure ratio is a closed region (α = 0 °) on the left side of the switching line in FIG. 6, the initial state where the blade angle α of each variable diffuser 8 is α = 0 ° (see FIG. 2). ) And is in the fully open state (see FIG. 3) where the blade angle α of each variable diffuser 8 is α = 35 °. Is done.

  That is, in the turbocharger control method according to the embodiment, when the characteristic point of the air flow rate and pressure ratio of the compressor crosses the switching line shown in the graph of FIG. The blade angle α, which is the geometry of the above, is simultaneously changed between an initial state where α = 0 ° (see FIG. 2) and a fully open state where α = 35 ° (see FIG. 3).

  Here, since the rotation speed of the compressor, the air flow rate, and the pressure ratio match on the switching line shown in the graph of FIG. 6, according to the turbocharger control method of one embodiment, the geometry of the variable diffuser 8 ( It is possible to suppress fluctuations in the torque of the vehicle engine when changing the blade angle α).

  The turbocharger control method of the present invention is not limited to one embodiment. For example, the blade angle α in the initial state of each variable diffuser 8 is not limited to α = 0 °, and can be changed as appropriate. The blade angle α in the fully open state is not limited to α = 35 °, and can be changed as appropriate. can do.

  Further, the blade angle α of each variable diffuser 8 is configured to be switched between two blade angles α, that is, an initial state and a fully open state, but is configured to be switched in a plurality of stages between the initial state and the fully open state. It may be configured to be switched continuously.

  Furthermore, the actuator for switching the blade angle α of each variable diffuser 8 is not limited to the drive motor 26, and can be changed to a negative pressure actuator that operates at the suction negative pressure of the vehicle engine.

  The inflow air pressure on the inlet side of the compressor housing 3 can be estimated from the air flow rate detected by the air flow sensor 21, and in this case, the inlet side air pressure sensor 22 can be omitted.

  The outlet air pressure at the outlet side of the compressor housing 3 can be estimated from the detection signal of a suction pipe pressure sensor provided in a vehicle engine (not shown). In this case, the outlet side air pressure sensor 23 is omitted. can do.

  Further, the air temperature on the inlet side of the compressor housing 3 can be estimated from a detection signal of an intake air temperature sensor provided in a vehicle engine (not shown). In this case, the inlet side air temperature sensor 24 is omitted. be able to.

  Here, the switching line shown in the graph of FIG. 6 is set based on the relational characteristic shown in the graph of FIG. 5, that is, the relational characteristic between the air flow rate and the pressure ratio with the rotation speed of the compressor as a parameter. It may be set based on the relational characteristic between the pressure ratio and the rotational speed with the air flow rate of the compressor as a parameter, or set based on the relational characteristic between the rotational speed and the air flow rate with the pressure ratio of the compressor as a parameter. May be.

  In these cases, the rotational speed of the compressor can be detected by a dedicated rotation sensor. However, in the case of the electrically assisted turbocharger configured to assist the rotation of the shaft 7 of the turbocharger 1 by the electric motor, the assist is provided. The rotational speed of the compressor can be detected from the rotational speed signal of the electric motor.

It is sectional drawing which shows schematic structure of the turbocharger to which the control method of the turbocharger which concerns on one Embodiment of this invention is applied. FIG. 2 is a front view of a base plate showing an initial state in which the variable diffuser shown in FIG. 1 is slightly opened. It is a front view of the baseplate which shows the fully open state of the variable diffuser shown in FIG. FIG. 3 is a rear view of the base plate shown in FIG. 2. 2 is a graph showing a relationship between an air flow rate and a pressure ratio of a compressor corresponding to an initial state and a fully opened state of the variable diffuser shown in FIG. FIG. 6 is a graph showing an extracted switching line for changing the geometry of the variable diffuser shown in FIG. 5. FIG. It is a block block diagram of the geometry change means which implement | achieves the control method of the turbocharger which concerns on one Embodiment. It is a flowchart which shows the process sequence of the control method of the turbocharger which concerns on one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbocharger 3 Compressor housing 6 Compressor impeller 8 Variable diffuser 9 Base plate 10 Rotating spindle 11 Driven arm 12 Unison ring 13 Guide roller 14 Link mechanism 20 Geometry changing means 21 Air flow sensor 22 Inlet air pressure sensor 23 Outlet air pressure sensor 24 Inlet air temperature sensor 25 Motor drive circuit 26 Drive motor

Claims (1)

  A method for controlling a turbocharger for a vehicle having a variable geometry diffuser in a compressor, wherein when the geometry of the variable diffuser is changed, the rotation speed, air flow rate and pressure ratio of the compressor are the same before and after the geometry change. The turbocharger control method is characterized in that the geometry is changed under the condition to be performed.

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