JP2008008202A - Turbine protection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of a turbocharger by inhibiting high stress from being applied to a turbine rotor at a time of a resonance to reduce the required strength of the turbocharger. <P>SOLUTION: A turbine protection device of a variable nozzle type turbocharger 2 annularly provided with a plurality of nozzle vanes of which angles can be adjusted on a nozzle on a turbine 2b side to enable a nozzle opening to be changed to arbitrary angles is provided with a turbine speed sensor 12 (rotation speed detection means ) detecting the rotation speed of the turbocharger 2 and a control device 13 changing the nozzle opening independently from normal control to move the rotation speed of the turbocharger 2 out of an alert rotation speed band when the rotation speed of the turbocharger 2 stays in the alert rotation speed band near the resonance rotation speed of the turbine rotor based on a detection signal 12a from the turbine speed sensor 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a turbine protection device for a variable nozzle type turbocharger.

Conventionally, there has been known a variable nozzle type turbocharger in which a large number of nozzle vanes capable of adjusting the angle are annularly provided in the nozzle part on the turbine side so that the nozzle opening can be arbitrarily changed. If a turbocharger of the type is employed, an ideal supercharging effect can be obtained by appropriately changing the capacity of the turbocharger in accordance with the engine speed, the running condition, and the like (see, for example, Patent Document 1). .
JP 2002-303147 A

  However, in the conventional variable nozzle type turbocharger, it is difficult to operate while avoiding the rotation speed (resonance rotation speed) at which the turbine impeller resonates. If the operation is continued for a long time or is repeated frequently, the turbine impeller may be stressed to cause damage.

  For this reason, a turbocharger with costly measures such as an increase in the natural frequency by increasing the rigidity of the turbine wheel, a reduction in forcing by adjusting the shape and pressure balance of the turbine case, and a significant improvement in material strength. This had to be adopted, leading to a significant increase in the cost of the turbocharger.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to reduce the necessary strength of a turbocharger so that stress at the time of resonance does not act strongly on a turbine impeller and to reduce the cost of the turbocharger. It is said.

  The present invention relates to a turbine protection device for a variable nozzle type turbocharger, in which a nozzle portion on a turbine side is annularly provided with a number of nozzle vanes capable of adjusting the angle so that the nozzle opening can be arbitrarily changed. A rotational speed detecting means for detecting the rotational speed of the turbocharger, and the warning when the rotational speed of the turbocharger continues for a predetermined time in a warning rotational speed band near the resonant rotational speed of the turbine wheel based on a detection signal from the rotational speed detecting means. And a control means for changing the nozzle opening degree independently of the normal control so as to remove the rotational speed of the turbocharger from the rotational speed range.

  Thus, in this way, when the rotation speed of the turbocharger continues for a predetermined time in the warning rotation speed band near the resonance rotation speed of the turbine wheel, the nozzle opening degree is made independent of normal control by the control means. Since the resonance avoidance control is executed to remove the turbocharger rotation speed from the warning rotation speed range, a situation in which the turbine impeller continues to resonate for a long time exceeding a predetermined time is avoided. The stress at the time of resonance does not act strongly on the impeller, and the required strength of the turbocharger is reduced as compared with the conventional case.

  Further, in the present invention, the fuel injection control for correcting the fuel injection pressure, the fuel injection timing, and the fuel injection amount for compensating the torque fluctuation caused by the control for removing the rotation speed of the turbocharger from the warning rotation speed band is controlled. It is preferable that it is comprised so that it may be performed simultaneously by a means.

  In this way, even if torque fluctuation is caused by executing resonance avoidance control that removes the rotation speed of the turbocharger from the warning speed band, the control means can compensate the fuel injection pressure and the fuel so that the torque fluctuation can be compensated. Since the injection timing and the fuel injection amount are corrected, torque fluctuation does not occur for the same accelerator opening.

  According to the turbine protection device of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, it is possible to avoid a situation where the turbine impeller continues to resonate for a long time beyond a predetermined time. The required strength of the turbocharger can be significantly reduced compared to the conventional method without causing the stress of the turbine to act strongly, so the natural frequency is improved by increasing the rigidity of the turbine impeller, and the forcing by adjusting the shape and pressure balance of the turbine case Thus, it is not necessary to take costly measures such as a reduction in power consumption and a significant improvement in material strength, and the cost for the turbocharger can be greatly reduced.

  (II) According to the invention described in claim 2 of the present invention, even if torque fluctuation is caused by executing resonance avoidance control for removing the rotation speed of the turbocharger from the warning rotation speed band, the torque fluctuation is controlled. Since it can be compensated by the fuel injection control by the means, it is possible to prevent a deterioration in drivability by preventing torque fluctuations for the same accelerator opening.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 3 show an example of an embodiment of a turbine protection device according to the present invention. Reference numeral 1 in FIG. 1 denotes an engine equipped with a variable nozzle type turbocharger 2. The introduced intake air 4 is sent to the compressor 2 a of the turbocharger 2 through the intake pipe 5, and the intake air 4 pressurized by the compressor 2 a is sent to the intercooler 6 to be cooled, and from the intercooler 6 Further, the intake 4 is guided to the intake manifold 7 and is distributed to each cylinder 8 of the engine 1 (the case of in-line 6 cylinders is illustrated in FIG. 1), and is discharged from each cylinder 8. The exhaust gas 9 is sent to the turbine 2b of the turbocharger 2 through the exhaust manifold 10, and the exhaust gas 9 that has driven the turbine 2b is discharged outside the vehicle through the exhaust pipe 11. It has become the jar.

  Here, the turbocharger 2 is equipped with a turbo rotation sensor 12 (rotation number detecting means) for detecting the rotation speed, and a detection signal 12a from the turbo rotation sensor 12 is an engine control computer (ECU: Electronic Control Unit). On the other hand, the control device 13 outputs a control signal 14a to the actuator 14 provided on the turbine 2b side of the turbocharger 2 in the control device 13. The capacity of the turbocharger 2 is changed as appropriate.

  That is, as shown in an example in FIG. 2, in the turbocharger 2, the nozzle vanes 15 of the turbine 2 b are annularly arranged in the nozzle portion 17 around the turbine wheel 16 and are connected to the nozzle ring plate 18 via the pins 19. The nozzle vanes 15 are mounted so as to be tiltable, and the angle of each nozzle vane 15 is changed in conjunction with the relative displacement of the link plate 20 in the circumferential direction with respect to the nozzle ring plate 18. The lever 14 is rotated through the link 22 by the tilting operation of the lever 21 by the actuator 14.

  For example, when the opening degree of the nozzle vane 15 is greatly opened with respect to a certain exhaust gas amount, the rotational speed of the exhaust gas 9 in the turbine 2b of the turbocharger 2 is lowered, and thereby the rotational speed of the turbine 2b is lowered, and the suction on the compressor 2a side. Since the amount of air decreases, the capacity of the turbocharger 2 increases as a result (a large amount of exhaust gas is required to obtain the same driving speed), and on the contrary, constant exhaust gas When the opening degree of the nozzle vane 15 is reduced with respect to the amount, the rotational speed of the exhaust gas 9 in the turbine 2b of the turbocharger 2 is increased, thereby increasing the rotational speed of the turbine 2b and increasing the intake air amount on the compressor 2a side. As a result, the capacity of the turbocharger 2 is reduced (a small amount of exhaust gas is required to obtain the same drive speed).

  And in normal control, the capacity | capacitance of the turbocharger 2 is controlled by the control apparatus 13 so that the most efficient supercharging according to an engine speed is achieved, More specifically, The capacity of the turbocharger 2 is changed in a plurality of stages, and the normal control for changing the capacity of the turbocharger 2 to low capacity at low speed, medium capacity at medium speed, and high capacity at high speed is the control device 13. To be done.

  However, in this embodiment, not only such normal control is executed by the control device 13, but also the rotational speed of the turbocharger 2 is based on the detection signal 12 a from the turbo rotation sensor 12 and the resonance rotation of the turbine impeller 16. Resonance avoidance control is performed in which the nozzle opening is changed independently from the normal control so as to remove the rotation speed of the turbocharger 2 from the warning rotation speed band when it continues for a predetermined time in the warning rotation speed band near the number. It has become.

  That is, the specific control procedure in the control device 13 is as shown in the flowchart of FIG. 3. In step S1, the rotational speed of the turbocharger 2 is detected based on the detection signal 12a from the turbo rotation sensor 12, and then in step S2. It is then determined whether the rotational speed [Nt] of the turbocharger 2 has entered a warning rotational speed band [A ≦ Nt ≦ B] near the resonant rotational speed of the turbine impeller 16 and has continued for a predetermined [T] seconds. (A, B, and T can be set arbitrarily.) If “NO”, the routine proceeds to step S3 and the normal control is continued. If “YES”, the routine proceeds to step S4 and the turbocharger starts from the warning speed range. The resonance avoidance control for removing the rotational speed of 2 is executed.

  Here, in removing the rotation speed of the turbocharger 2 from the warning rotation speed range, the rotation speed may be increased or decreased appropriately so that the rotation speed of the turbocharger 2 deviates from the warning rotation speed band earlier. It is preferable from the viewpoint of safety that the nozzle opening degree is opened and the rotational speed of the turbocharger 2 is decreased so as to be out of the warning rotational speed range.

  In the example shown in FIG. 1, an accelerator sensor 23 (load sensor) that detects the accelerator opening (the depression angle of the accelerator pedal) as a load of the engine 1 is provided, and the engine is positioned at an appropriate position of the engine 1. An engine rotation sensor 24 for detecting the rotation speed is provided, and detection signals 23 a and 24 a from the accelerator sensor 23 and the engine rotation sensor 24 are input to the control device 13.

  In the control device 13, an appropriate control signal 25 a is output to the fuel injection device 25 based on the detection signals 23 a and 24 a from the accelerator sensor 23 and the engine rotation sensor 24 so that the output requested by the driver is exhibited. However, the correction of the fuel injection pressure, the fuel injection timing, and the fuel injection amount for compensating the torque fluctuation caused by the control for removing the rotational speed of the turbocharger 2 from the warning rotational speed band is performed simultaneously. To be done.

  That is, the fuel injection device 25 is configured to inject fuel accumulated in a common rail (not shown) into each cylinder 8 by a plurality of injectors, and the pressure in the common rail is controlled by a control signal 25a from the control device 13. Adjustment is made to correct the fuel injection pressure, and the opening timing and opening time of the solenoid valve of each injector are adjusted to correct the fuel injection timing and the fuel injection amount.

  In the figure, 26 is an EGR pipe for recirculating a part of the exhaust gas 9 from the exhaust manifold 10 to the intake pipe 5, 27 is an EGR valve installed in the middle of the EGR pipe 26, and 28 is an exhaust gas to be recirculated. An EGR cooler 29 for water-cooling 9 and a muffler provided on the downstream side of the exhaust pipe 11 are shown.

  Thus, when the turbine protection device is configured in this way, when the rotation speed of the turbocharger 2 continues for a predetermined time in the warning rotation speed band near the resonance rotation speed of the turbine impeller 16, the control from the control device 13 is performed. The nozzle opening is changed independently from the normal control by the signal 14a, and the resonance avoidance control for removing the rotational speed of the turbocharger 2 from the warning rotational speed band is executed, so that the turbine impeller 16 is longer than a predetermined time. The situation of continuing resonance is avoided in advance, and thereby, the stress at the time of resonance does not act strongly on the turbine impeller 16, and the required strength of the turbocharger 2 is reduced as compared with the conventional case.

  Particularly in this embodiment, the fuel injection for correcting the fuel injection pressure, the fuel injection timing, and the fuel injection amount for compensating for the torque fluctuation caused by the control for removing the rotation speed of the turbocharger 2 from the warning rotation speed band. Since control is performed simultaneously by the control device 13, even if torque fluctuation is caused by executing resonance avoidance control that removes the rotation speed of the turbocharger 2 from the warning rotation speed band, the torque fluctuation is compensated. The control device 13 corrects the fuel injection pressure, the fuel injection timing, and the fuel injection amount so that torque fluctuation does not occur for the same accelerator opening.

  Therefore, according to the above-described embodiment, it is possible to avoid a situation in which the turbine impeller 16 continues to resonate for a long time beyond a predetermined time, thereby preventing the stress at the time of resonance from acting strongly on the turbine impeller 16. Thus, the required strength of the turbocharger 2 can be significantly reduced as compared with the conventional case, so that the natural frequency is improved by increasing the rigidity of the turbine impeller 16, and the forcing force is reduced by adjusting the shape and pressure balance of the turbine case. It is not necessary to take costly measures such as a significant improvement in material strength, and the cost for the turbocharger 2 can be greatly reduced.

  In addition, even if torque fluctuation is caused by executing resonance avoidance control that removes the rotation speed of the turbocharger 2 from the warning rotation speed band, the torque fluctuation can be compensated by fuel injection control by the control device 13. It is possible to prevent the drivability from deteriorating by preventing torque fluctuation for the same accelerator opening.

  The turbine protection device of the present invention is not limited to the above-described embodiment, and the mechanism for adjusting the angle of the turbine nozzle vane in the variable nozzle type turbocharger is not necessarily limited to the illustrated example. Of course, various modifications can be made without departing from the scope of the invention.

It is the schematic which shows an example of the form which implements this invention. FIG. 2 is a detailed view of a tilting mechanism of a nozzle vane of the turbine of FIG. 1. It is a flowchart which shows the specific control procedure of the control apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Turbocharger 2a Compressor 2b Turbine 12 Turbo rotation sensor (rotation number detection means)
12a Detection signal 13 Control device (control means)
14 Actuator 14a Control signal 15 Nozzle vane 16 Turbine wheel 17 Nozzle part 25 Fuel injection device 25a Control signal

Claims (2)

  A turbine protection device for a variable nozzle type turbocharger that is provided with an annular number of nozzle vanes that can be adjusted in angle in the nozzle part on the turbine side so that the nozzle opening can be arbitrarily changed. Rotation speed detection means to detect, and based on the detection signal from the rotation speed detection means, when the rotation speed of the turbocharger continues for a predetermined time in a warning rotation speed band near the resonance rotation speed of the turbine impeller, from the warning rotation speed band A turbine protection device comprising: control means for changing the nozzle opening independently from the normal control so as to remove the rotational speed of the turbocharger.   Fuel injection control for correcting fuel injection pressure, fuel injection timing, and fuel injection amount to compensate for torque fluctuations caused by control to remove the turbocharger rotation speed from the warning rotation speed band is performed simultaneously by the control means. The turbine protection device according to claim 1, wherein the turbine protection device is configured.

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