JP2014084772A - Life estimation apparatus of exhaust turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate stress generated in a turbine impeller and to estimate life of an exhaust turbocharger at higher accuracy from the magnitude of generated stress and a stress generation frequency.SOLUTION: A life estimation apparatus of an exhaust turbocharger includes: resonance generation frequency acquisition means for acquiring a resonance generation frequency by counting frequencies when a rotation frequency of an actual turbine impeller 11 becomes a resonance rotation frequency; expansion ratio acquisition means for acquiring an expansion ratio when the rotation frequency of the actual turbine impeller 11 becomes the resonance rotation frequency on the basis of a rotation frequency of an internal combustion engine 1 and load of the internal combustion engine 1; resonance stress acquisition means for acquiring resonance stress generated in the turbine impeller 11 on the basis of the acquired expansion ratio; and life estimation means for estimating the life of the turbine impeller 11 by referring to a fatigue limit curve on the basis of the acquired resonance generation frequency and the resonance stress.

Description

  The present invention relates to a life estimation technique for an exhaust turbocharger using exhaust energy used for an internal combustion engine or the like.

  Conventionally, in internal combustion engines, it is possible to increase the intake air volume while reducing the exhaust volume and reduce the pumping loss. This contributes to the promotion of higher output and lower fuel consumption while keeping the exhaust clean. As a new technology, an exhaust turbocharger (exhaust supercharger) using exhaust energy has been adopted.

  On the other hand, stress is generated in the turbine wheel of the exhaust turbocharger, and the stress affects the life of the turbine wheel and the exhaust turbocharger. For this reason, the exhaust turbocharger has been overhauled before the exhaust turbocharger breaks and other malfunctions, assuming that the life of the exhaust turbocharger is based on experience and the experience, and so on. There are actual situations such as replacement with new or rebuilt products.

  However, since the magnitude of the stress generated in the turbine impeller and the number of repetitions vary greatly depending on the operating conditions of the internal combustion engine, it is difficult to accurately know the overhaul time and replacement time for extending the life of the exhaust turbocharger. The actual situation is that a method of responding early is adopted. Even so, there is a possibility that a problem may occur before replacement.

For this reason, Patent Document 1 discloses a turbocharger lifetime in which the lifetime of the turbocharger is predicted based on the relationship between the compressor inlet pressure and the compressor outlet pressure of the turbocharger. A decision device has been proposed.
Patent Document 2 proposes a technique for monitoring the fatigue life of a turbocharger based on wheel speed (turbine rotational speed) or turbine intake air temperature.

JP 2005-248952 A Special Table 2002-544443

  However, even the techniques described in Patent Document 1 and Patent Document 2 still have room for improvement, and it is possible to predict the life of the turbine impeller and the exhaust turbocharger with higher accuracy. It is desired.

  The present invention has been made in view of such circumstances, and estimates the stress generated in the turbine impeller while having a simple and low-cost configuration, and the turbine blade with higher accuracy from the magnitude and frequency of the generated stress. An object of the present invention is to provide an exhaust gas turbocharger life estimation device capable of estimating the life of a vehicle and thus an exhaust gas turbocharger.

For this reason, the exhaust gas turbocharger life estimation device according to the present invention is
An exhaust turbocharger life estimation device for estimating the life of an exhaust turbocharger interposed in an exhaust passage of an internal combustion engine,
Resonance generation number acquisition means for acquiring the number of times of occurrence of resonance by counting the number of times that the actual rotation speed of the turbine wheel is the resonance speed of the turbine wheel,
Expansion ratio acquisition means for acquiring the expansion ratio when the actual rotational speed of the turbine impeller becomes the resonant rotational speed of the turbine impeller based on the rotational speed of the internal combustion engine and the load of the internal combustion engine;
Resonance stress acquisition means for acquiring resonance stress generated in the turbine impeller based on the expansion ratio acquired by the expansion ratio acquisition means;
Life estimation means for estimating the life of the turbine impeller by referring to the fatigue limit curve based on the number of resonance occurrences acquired by the resonance occurrence number acquisition means and the resonance stress acquired by the resonance stress acquisition means; ,
It is characterized by including.

  In the present invention, the means for obtaining the number of times of resonance generation refers to an equal turbine rotation speed diagram determined on the basis of the rotation speed of the internal combustion engine and the load of the internal combustion engine. By counting the number of passes through (or straddling) the number lines, the number of resonance occurrences can be acquired.

  According to the present invention, the stress generated in the turbine impeller is estimated with a simple and low-cost configuration, and the turbine impeller and the exhaust turbocharger are more accurately determined from the magnitude and frequency of the generated stress. It is possible to provide an exhaust gas turbocharger lifetime estimation device that can estimate the lifetime of the exhaust gas.

1 is a diagram schematically illustrating an overall configuration of an internal combustion engine including an exhaust turbocharger according to an embodiment of the present invention. It is a figure explaining an example of the relationship between the natural frequency of the turbine impeller of an exhaust turbocharger, and the resonant rotation speed. An example of an equiturbine impeller rotational speed diagram (map) determined based on the engine rotational speed of the internal combustion engine and a load (fuel injection amount), and the resonance rotational speed line of the graph are the actual turbine impeller rotational speed ( It is a figure explaining a mode that driving state) passes. It is a figure which shows an example of the isoexpansion ratio diagram (map) defined based on the engine speed of an internal combustion engine, and load (fuel injection amount). It is a figure which shows an example of the relationship (map) of an expansion ratio (P3 / P3) and resonance stress (excitation stress). It is a figure which shows an example of the SN diagram (fatigue limit curve) which made the resonance stress (amplitude of Stress) the vertical axis | shaft, and made the frequency | count of resonance generation (Number) the horizontal axis. It is a figure for demonstrating the SN value (fatigue limit curve) same as the above, and the total value of the lifetime for each resonance stress area | region. It is a time chart which shows an example of the driving history information (actual driving data) of an internal-combustion engine over time.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

  As shown in FIG. 1, an exhaust turbocharger (exhaust supercharger) 10 is interposed in an exhaust passage 2 of the internal combustion engine 1, and a turbine impeller 11 (a rotating body with a blade that is rotated by receiving exhaust) is exhausted. The impeller 12 mounted on the same axis is rotationally driven by the rotational energy, and the intake air is compressed by the rotationally driven impeller 12 to be supercharged. The supply air is supplied to the combustion chamber 5 while being cooled by 4.

  In the engine control unit (ECU) 20 that controls the fuel injection amount and the injection timing of the internal combustion engine 1 according to the present embodiment, various types such as the rotational speed (rotational speed) of the internal combustion engine, the fuel injection amount of the internal combustion engine 1 and the like. Information is acquired.

(1) About the natural frequency of the turbine impeller 11 The turbine impeller 11 has a natural frequency determined by the shape, thickness, height, and the like of its blades.
As shown in FIG. 2, there are frequency characteristic lines representing frequency characteristics for each of the primary rotation, secondary rotation,... When the frequency characteristic line of the turbine rotation order matches (crosses), a resonance phenomenon occurs at the turbine rotation speed (resonance rotation speed).

  In addition, by designing the turbine impeller 11 so that the resonance rotational speed does not exist in the normal use region, the occurrence of resonance can be avoided and the life of the turbine impeller 11 can be extended. The frequency needs to be a high frequency. However, in order to set the natural frequency of the turbine impeller 11 to a high frequency, it is necessary to reduce the blade height or increase the blade height. Such a change leads to a decrease in performance as the exhaust turbocharger 10. Because it is a change to, it is difficult to adopt.

  (2) When the forcing force (expansion ratio = P3 / P4) to the turbine impeller 11 is large at the time of resonance, a large stress greater than the fatigue strength is generated in the turbine impeller 11 according to the frequency of occurrence of the large stress. Thus, the life of the turbine impeller 11 is determined.

(3) That is, in order to estimate (predict) the life of the turbine impeller 11,
A. How many times has resonance occurred?
B. What is the magnitude of the forcing force (excitation force: expansion ratio) when resonance occurs?
C. What is the magnitude of the generated stress relative to the expansion ratio?
If these A to C can be grasped, the life of the turbine impeller 11 can be estimated (predicted) from a minor rule (Miner's Rule: SN curve (fatigue limit curve): see FIG. 6 and the like). .

  For this reason, in the present embodiment, the engine control unit (ECU) 20 follows the following steps in accordance with the life of the turbine impeller (exhaust turbocharger) (replacement time or overhaul time, or the remaining life until the life). (Period) is predicted (estimated).

That is,
In step 1, based on the rotational speed of the internal combustion engine 1 and the load (fuel injection amount) of the internal combustion engine 1, a map (an equal turbine rotational speed curve as shown in FIG. 3) obtained in advance by experiments or the like , The change in the turbine rotational speed determined from the actual operating state is monitored, and it is acquired (monitored) whether or not the resonant rotational speed has been passed (crossed).
Note that the resonance rotational speed is determined for each rotational order by referring to, for example, a map as shown in FIG.

  By the way, when the turbine rotational speed sensor which detects the rotational speed (turbine rotational speed: rpm) of the turbine impeller 11 is provided, the turbine rotational speed acquired from the turbine rotational sensor is monitored. It is good.

  Subsequently, in Step 2, when the turbine rotation speed passes (strands) the resonance rotation speed in Step 1, based on the rotation speed of the internal combustion engine 1 and the load (fuel injection amount) of the internal combustion engine 1, The internal combustion engine 1 when the turbine speed passes (strides) the resonance speed (at the time of resonance) with reference to a map (isoexpansion ratio diagram as shown in FIG. 4) or the like obtained in advance by experiments or the like The expansion ratio determined from the rotational speed of the engine and the load (fuel injection amount) of the internal combustion engine 1 is acquired.

  Step 2 executed by the engine control unit (ECU) 20 corresponds to the expansion ratio acquisition means according to the present invention.

  In step 3, a map (an “expansion ratio” as shown in FIG. 5) and a “resonant stress (stress generated in a turbine impeller)” obtained from experiments and simulations in advance from the expansion ratio acquired in step 2, The stress (resonant stress) generated in the turbine impeller 11 is acquired with reference to the above. The map of FIG. 5 can be set according to the specifications of the turbine impeller 11 (blade shape, thickness, height, etc.).

  Here, Step 3 executed by the engine control unit (ECU) 20 corresponds to the resonance stress acquisition means according to the present invention.

  Next, in step 4, when the turbine rotation speed has passed (stradded) the resonance rotation speed in step 1, the number of resonance occurrences is counted up (incremented) to obtain a new resonance occurrence number, and the new Based on the number of resonance occurrences and the resonance stress obtained in step 3, refer to the SN diagram (miner's rule: (fatigue limit curve)) as shown in FIG. The replacement time or overhaul time (life; remaining until the life) of the turbine impeller 11 is estimated (predicted).

  Here, the “processing for acquiring a new number of resonance occurrences” in step 4 executed by the engine control unit (ECU) 20 corresponds to the resonance occurrence number acquisition means according to the present invention.

  Further, referring to the SN diagram (fatigue limit curve) based on “new number of resonance occurrences and resonance stress” in Step 4 executed by the engine control unit (ECU) 20, the turbine wheel 11 The process of estimating (predicting) the replacement time or overhaul time (life; remaining until the life) of the "corresponds to the life estimation means according to the present invention.

  For example, as shown in FIG. 7, the engine control unit (ECU) 20 obtains the ratio and percentage (%) of the number of occurrences of resonance up to the fatigue limit number for each region of the generated resonance stress, and these ratios and percentages ( %) Can be stored and updated.

  For example, the ratio of the number of occurrences of resonance in each resonance stress (region) to the fatigue limit number and the total value of percentage (%) (0.65 (65% in FIG. 7)) are 0.8 and 80 (%). ), It is assumed that the exhaust turbocharger 10 is about to be replaced or overhauled, and the engine control unit (ECU) 20 lights up or notifies the instrument panel 30 near the driver's seat. It can be configured to notify a driver or the like by generating a sound or making a voice announcement.

  In a service factory or the like, the ratio or percentage (%) of the number of resonance occurrences up to the fatigue limit number in each resonance stress (region) stored in the engine control unit (ECU) 20 by a personal computer or a dedicated computer. As a configuration that can read out the total value, the service staff or the like knows how close the exhaust turbocharger 10 is to the replacement or overhaul time, and informs the customer how long it is until the replacement time. Therefore, it is possible to contribute to service improvement and the like.

  In the present embodiment, the engine control unit (ECU) 20 or service staff refers to, for example, the degree of use of the vehicle (annual mileage, etc.), until the replacement or overhaul time of the exhaust turbocharger 10. It is possible to notify you when the year is about to come.

  By the way, in the present embodiment, the engine control unit (ECU) 20 includes software (flowchart) for executing the above steps in a storage unit such as a ROM, and the software is stored in the internal combustion engine 1 every predetermined time (several milliseconds). The operation history information (actual travel data history) including the rotation speed of the internal combustion engine 1 and the load (fuel injection amount) of the internal combustion engine 1 (FIG. 8 etc.) (Refer to FIG. 3 to FIG. 5 based on the operation history information) at a predetermined timing (when the operation is stopped or started), and the turbine rotational speed passes through the resonant rotational speed. And the resonance ratio is acquired as the expansion ratio when the turbine rotation speed passes (reverses) the resonance rotation speed. Based on these, By referring to the S-N diagram shown in 6 and 7, it is also possible to configure as the life of the turbine wheel 11 (remaining before the life) is estimated (predicted).

  In the embodiment described above, the type of the exhaust turbocharger is not particularly limited, and the present invention can be applied to, for example, a variable displacement exhaust turbocharger, such as a variable nozzle turbocharger (VNT) and others. The present invention is also applicable to a variable displacement exhaust turbocharger of the type

  By the way, the internal combustion engine according to the present invention is not particularly limited. For example, the present invention is applicable not only to a vehicle mounted on a vehicle but also to a stationary type, and also a diesel engine, a gasoline engine, The present invention is applicable to an internal combustion engine that burns other fuels regardless of the combustion method.

  The embodiment described above is merely an example for explaining the present invention, and various modifications can be made without departing from the gist of the present invention.

1 Internal combustion engine
2 Exhaust passage 3 Intake passage 4 Intercooler 5 Combustion chamber 10 Exhaust turbocharger (exhaust supercharger)
11 Turbine impeller 12 Impeller 20 Engine control unit (ECU)
30 Instrument panel

Claims (2)

An exhaust turbocharger life estimation device for estimating the life of an exhaust turbocharger interposed in an exhaust passage of an internal combustion engine,
Resonance generation number acquisition means for acquiring the number of times of occurrence of resonance by counting the number of times that the actual rotation speed of the turbine wheel is the resonance speed of the turbine wheel,
Expansion ratio acquisition means for acquiring the expansion ratio when the actual rotational speed of the turbine impeller becomes the resonant rotational speed of the turbine impeller based on the rotational speed of the internal combustion engine and the load of the internal combustion engine;
Resonance stress acquisition means for acquiring resonance stress generated in the turbine impeller based on the expansion ratio acquired by the expansion ratio acquisition means;
Life estimation means for estimating the life of the turbine impeller by referring to the fatigue limit curve based on the number of resonance occurrences acquired by the resonance occurrence number acquisition means and the resonance stress acquired by the resonance stress acquisition means; ,
An exhaust gas turbocharger life estimation device characterized by comprising   The means for acquiring the number of resonance occurrences refers to an equal turbine rotation speed diagram determined based on the rotation speed of the internal combustion engine and the load of the internal combustion engine, and the actual turbine rotation speed passes through the resonance rotation speed line. 2. The exhaust gas turbocharger life estimation apparatus according to claim 1, wherein the number of times of resonance is obtained by counting the number of times of occurrence.

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