Compressor life prediction device

Abstract

Predict the lifespan of the compressor. [Solution] A life prediction device for predicting the life of a compressor in a vehicle comprising a compressor including an impeller that rotates based on intake air directed toward the engine, a turbine including a wheel that rotates integrally with the impeller, and an EGR passage that recirculates a portion of the exhaust gas from the engine flowing downstream of the turbine's exhaust passage as EGR gas upstream of the compressor's intake passage, comprising: a first calculation means that calculates the amount of condensed water based on EGR gas based on weather data at the vehicle's travel location and data on the amount of water generated by the combustion of fuel supplied to the engine; a second calculation means that calculates the diameter of condensed water droplets based on information defining the relationship between the amount of condensed water, the vehicle's speed, and the intake air volume of the turbocharger; and a prediction means that predicts the life based on the diameter of the droplets, the collision velocity of the droplets with the impeller according to the rotation speed of the turbocharger, and the design information of the impeller.

Description

[Technical Field]

[0001] This invention relates to a compressor life prediction device. [Background technology]

[0002] Engines equipped with an LPL (Low Pressure Loop) type EGR (Exhaust Gas Recirculation) mechanism and a turbocharger are known. In such engines, when EGR is running, the EGR gas, which is part of the engine's exhaust, is cooled by a cooler, and condensed water is generated inside the cooler due to the condensation of moisture contained in the EGR gas. Condensation can also be generated when the EGR gas condenses in the intake passage. When condensed water is generated, large droplets of condensed water flow directly into the turbocharger's compressor.

[0003] In a compressor, multiple impellers rotate at high speed. When liquid droplets flow into the compressor, they collide with the rapidly rotating impellers, causing wear and damage to the compressor. This phenomenon is called erosion. Erosion is more pronounced the larger the diameter of the colliding droplets. To suppress compressor damage due to erosion, techniques have been proposed to reduce the diameter of the droplets and lessen the impact force on the impellers. This can extend the lifespan of the compressor (see, for example, Patent Documents 1 to 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-070078 [Patent Document 2] Japanese Patent Publication No. 2016-089667 [Patent Document 3] Japanese Patent Publication No. 2003-121172 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, even if the lifespan of the compressor is extended, there is a limit to its lifespan. To encourage the replacement of the turbocharger before the compressor reaches the end of its lifespan, it is desirable to predict the compressor's lifespan.

[0006] Therefore, the present invention aims to provide a life prediction device for predicting the lifespan of a compressor. [Means for solving the problem]

[0007] The life prediction device according to the present invention is a life prediction device for predicting the life of a compressor in a vehicle comprising: a compressor including an impeller that rotates based on intake air directed toward the engine; a turbocharger including a wheel that rotates integrally with the impeller; and an EGR passage that recirculates a portion of the exhaust gas from the engine flowing downstream of the exhaust passage of the turbine as EGR gas upstream of the intake passage of the compressor, and comprises: a first calculation means for calculating the amount of condensed water based on the EGR gas based on first data representing the weather conditions at the location where the vehicle is traveling and second data representing the amount of water generated by the combustion of fuel supplied to the engine; a second calculation means for calculating the diameter of the condensed water droplets based on predetermined information defining the relationship between the amount of condensed water, the vehicle speed, and the intake air volume of the turbocharger; and a prediction means for predicting the life based on the diameter of the droplets, the collision velocity of the droplets with the impeller according to the rotation speed of the turbocharger, and design information of the impeller. [Effects of the Invention]

[0008] According to the present invention, the lifespan of a compressor can be predicted. [Brief explanation of the drawing]

[0009] [Figure 1] This is an example of a lifespan prediction system. [Figure 2] This flowchart shows an example of ECU operation. [Figure 3]This is an example of three-dimensional particle size map information.

Embodiments for Carrying out the Invention

[0010] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[0011] As shown in FIG. 1, the vehicle 10 mounts an engine 11. An exhaust gas turbine type supercharger 20 for supercharging the intake air (hereinafter referred to as intake air) directed toward the engine 11 is provided in the intake passage 12 of the engine 11. The supercharger 20 includes a compressor 21 and a turbine 22. The compressor 21 includes an impeller 21b that rotates based on the intake air directed toward the engine 11. An intercooler 13 for cooling the supercharged intake air is connected to the intake passage 12 downstream of the intake air outlet 21a of the compressor 21.

[0012] A throttle body 14 is provided in the intake passage 12 downstream of the intercooler 13. A throttle valve 14a controlled by an ECU (Electronic Control Unit) 100 is provided inside the throttle body 14. The intake passage 12 downstream of the throttle body 14 is connected to the intake port of the engine 11. Note that the ECU 100 is an example of a life prediction device having a first calculation means, a second calculation means, and a prediction means.

[0013] A turbine 22 of the supercharger 20 is provided in an exhaust passage 30 connected to the exhaust port of the engine 11. The turbine 22 includes a wheel 22b that rotates integrally with the impeller 21b via a turbine shaft 22s. An exhaust gas purification device 40 for reducing nitrogen oxides contained in the exhaust gas is provided in the exhaust passage 30 downstream of the exhaust air outlet 22a of the turbine 22.

[0014] The engine 11 is provided with an EGR passage 56 that recirculates a part of the exhaust gas from the engine 11 flowing downstream of the exhaust passage 30 of the turbine 22 as EGR gas to upstream of the intake passage 12 of the compressor 21. Specifically, the upstream end of the EGR passage 56 is connected to the exhaust passage 30 downstream of the turbine 22 of the supercharger 20, more specifically, downstream of the exhaust gas purification device 40 in the exhaust flow. The downstream end of the EGR passage 56 is connected to the intake passage 12 upstream of the compressor 21 of the supercharger 20 in the intake flow.

[0015] The EGR passage 56 is provided with an EGR cooler 57 that cools the EGR gas. Further, an EGR control valve 58 that adjusts the recirculation amount of the EGR gas based on the control by the ECU 100 is provided in the EGR passage 56 downstream of the EGR cooler 57.

[0016] When the EGR is executed by opening the EGR control valve 58 to recirculate the EGR gas to the engine 11, the high-temperature EGR gas is cooled by the EGR cooler 57. For this reason, condensed water is generated and stays in the EGR cooler 57 due to the condensation of the moisture contained in the EGR gas. The condensed water flows into the intake passage 12 through the EGR control valve 58 in the open state along with the flow of the EGR gas. Further, when the EGR is executed, the EGR gas flowing in the intake passage 12 contacts the wall surface in the intake passage 12 at a temperature below the dew point, so that the moisture in the intake air and the EGR gas may condense and adhere to the wall surface in the intake passage 12 as condensed water.

[0017] Since the compressor 21 of the turbocharger 20 is provided in the intake passage 12, if condensed water flows into or adheres to the intake passage 12, large droplets of condensed water will flow into the compressor 21. Because multiple impellers 21b rotate at high speed in the compressor 21, erosion may occur when droplets flow into the compressor 21. In other words, the droplets colliding with the high-speed rotating impellers 21b may cause wear on the impellers 21b and damage to the compressor 21. For example, the plating applied to the surface of the impellers 21b may peel off, causing wear on the impellers 21b and damage to the compressor 21. As will be described in detail later, in this embodiment, the ECU 100 predicts the lifespan of the compressor 21. If the lifespan of the compressor 21 can be predicted, necessary measures can be taken, such as prompting the replacement of the turbocharger 20 before the compressor 21 is damaged and the turbocharger 20 fails.

[0018] The ECU 100 is electrically connected to a vehicle speed sensor 61 that detects the vehicle speed of the vehicle 10, a rotation speed sensor 62 that detects the rotation speed of the impeller 21b per unit time as the turbo rotation speed, and an airflow meter 63 that detects the amount of intake air flowing into the compressor 21. The ECU 100 is also connected to an in-vehicle communication device 64. The in-vehicle communication device 64 is equipped with an antenna ATN and can communicate with a mobile base station BS via wireless communication WL.

[0019] The ECU100 is an electronic control unit equipped with a processor such as a CPU (Central Processing Unit), memory such as RAM (Random Access Memory), ROM (Read Only Memory), and NVM (Non-Volatile Memory), and input / output ports. The processor performs various calculations, including vehicle 10 driving control and compressor 21 life prediction. The memory stores programs and data used for driving control and life prediction, as well as 3D particle size map information, which will be described later.

[0020] The mobile base station BS is connected to a weather database server 65 via a communication network NW, such as a LAN (Local Area Network) or the internet. Therefore, the ECU 100 can access the weather database server 65 via the in-vehicle communication device 64. The vehicle 10 and the weather database server 65 realize the life prediction system ST.

[0021] The weather database server 65 manages daily weather data, including temperature and humidity, on a regional basis. The weather data shown is an example of the first data set. The ECU 100 can obtain weather data for the region including the vehicle's travel location from the weather database server 65 via the in-vehicle communication device 64.

[0022] When the ECU100 acquires weather data, it calculates the amount of condensate generated based on the condensation of moisture contained in the EGR gas, based on the weather data and moisture content data, which includes the amount of moisture generated when fuel is burned in cylinder 11a of the engine 11. The moisture content data is an example of the second data.

[0023] More specifically, the ECU 100 calculates the amount of first moisture contained in the intake air flowing through the intake passage 12 using an estimation formula that utilizes the humidity included in the weather data, the intake air volume detected by the airflow meter 63, the water vapor concentration indicating the proportion of water vapor in the intake air, and the recirculation rate of the EGR gas returned to the intake passage 12. The water vapor concentration is calculated using various methods described in known patent documents, such as Japanese Patent Application Publication No. 2022-120376.

[0024] Furthermore, the ECU 100 calculates the amount of second moisture contained in the EGR gas and generated by the combustion of fuel, using an estimation formula that utilizes the amount of fuel supplied to cylinder 11a of engine 11 and the recirculation rate of the EGR gas. The calculation of the second moisture is also performed using various methods described in the known patent documents mentioned above. Once the first moisture amount and the second moisture amount are calculated, the ECU 100 generates moisture amount data including the first and second moisture amounts and calculates the saturated water vapor amount in the portion of the intake passage 12 through which the EGR gas flows. The ECU 100 calculates the amount of condensed water by subtracting the saturated water vapor amount from the sum of the first and second moisture amounts included in the moisture amount data.

[0025] The ECU 100 calculates the amount of condensed water and then calculates the particle size of the condensed water droplets based on predetermined three-dimensional particle size map information that defines the relationship between the amount of condensed water, the vehicle speed of the vehicle 10 detected by the vehicle speed sensor 61, and the intake air volume of the supercharger 20. As will be described in detail later, instead of the intake air volume of the supercharger 20, the engine speed of the engine 11 and the vehicle speed of the vehicle 10, which are correlated with the intake air volume of the supercharger 20, may be used. Once the ECU 100 calculates the particle size of the condensed water droplets, it predicts the lifespan of the compressor 21 based on the droplet size, the droplet collision velocity, the number of droplet collisions, and the design information of the impeller 21b. For example, the ECU 100 predicts the date and time or mileage at which the plating on the impeller 21b disappears as the lifespan of the compressor 21. The droplet collision velocity is calculated, for example, based on the rotational speed of the impeller 21b (specifically, the peripheral speed of the collision point), the blade angle of the impeller 21b, and the intake volume of the supercharger 20. The number of droplet collisions is calculated, for example, based on the droplet collision velocity, the amount of condensed water generated, and the droplet size.

[0026] When the ECU 100 predicts the lifespan of the compressor 21, it outputs a replacement urging signal that includes the lifespan of the compressor 21. When the ECU 100 outputs a replacement urging signal, the in-vehicle communication device 64 transmits the replacement urging signal via wireless communication WL to a vehicle management server (not shown) different from the weather DB server 65. The vehicle management server manages the degree of deterioration of the turbochargers or compressors of multiple vehicles, including vehicle 10.

[0027] A vehicle management officer with access to the vehicle management server can check the lifespan of the compressor 21 included in the replacement prompt signal. If it is determined that the lifespan is below a threshold, the officer can contact the vehicle dealership to prompt the replacement of the turbocharger 20 before the impeller 21b fails. The ECU 100 may also output the replacement prompt signal to a display or tachometer installed in the vehicle 10. This allows the user of the vehicle 10 to become aware of the need to replace the turbocharger 20.

[0028] The operation of the ECU100 will be explained with reference to Figures 2 and 3.

[0029] As shown in Figure 2, the ECU 100 acquires weather data (step S1). More specifically, the ECU 100 acquires weather data from the weather DB server 65 via the in-vehicle communication device 64. Once the ECU 100 acquires the weather data, it generates moisture content data (step S2). As described above, the ECU 100 calculates a first moisture content based on the weather data and a second moisture content contained in the EGR gas based on the combustion of fuel, and then generates moisture content data that includes the first and second moisture content.

[0030] When ECU100 generates moisture content data, it calculates the amount of condensed water (step S3). ECU100 can calculate the amount of condensed water by subtracting the saturated water vapor amount from the sum of the first moisture content and the second moisture content included in the moisture content data. When ECU100 calculates the amount of condensed water, it calculates the particle size of the condensed water droplets (step S4). As described above, ECU100 can calculate the particle size of the condensed water droplets based on the three-dimensional particle size map information.

[0031] Here, as shown in Figure 3, the 3D particle size map information is information that can identify the particle size of condensed water droplets for each combination of vehicle speed 10, intake air volume of supercharger 20, and amount of condensed water. Although not shown, the 3D particle size map information can also identify the number of condensed water droplets in addition to the particle size of the droplets. The 3D particle size map information is generated by prior experiments on a vehicle-by-vehicle basis and on an engine 11 operating condition basis. Note that instead of the intake air volume of supercharger 20, the engine speed of engine 11 and the vehicle speed of vehicle 10, which are correlated with the intake air volume of supercharger 20, may be used.

[0032] Based on this three-dimensional particle size map information, the ECU 100 can determine the particle size and number of condensate droplets according to the combination of the vehicle speed of the vehicle 10, the intake air volume of the supercharger 20, and the amount of condensate. Once the ECU 100 has determined the particle size and number of condensate droplets, it multiplies the turbo rotation speed detected by the rotation speed sensor 62 by the number of droplets to calculate the number of times the droplets collide with the impeller 21b (hereinafter referred to as the number of collisions). The ECU 100 also calculates the collision speed of the droplets with the impeller 21b (hereinafter referred to as the collision speed) based on the intake air volume detected by the airflow meter 63 and the turbo rotation speed.

[0033] The ECU100 calculates the particle size of the condensed water droplets and then estimates the amount of erosion (step S5). The amount of erosion is the decrease in mass of the impeller 21b due to erosion.

[0034] The amount of erosion can be expressed by the following formula (1), based on the base erosion amount A, which serves as the basis for the amount of erosion, a correction factor B related to impeller hardness, a correction factor C related to droplet particle size, a correction factor D related to droplet impact velocity, and a correction factor E related to surface roughness. The base erosion amount A and the correction factors B-E will be explained below. Erosion amount = A × B × C × D × E ... (1)

[0035] The base erosion amount A is the erosion amount before correction without considering other influencing factors. The base erosion amount A can be expressed, for example, by the following formula (2). Base erosion amount A = 8 × 10 -14 (Number of collisions) 2 + 2 × 10 -6 (Number of collisions) ··· (2)

[0036] The correction coefficient B is a coefficient for correcting the hardness of the impeller 21b. The harder the material of the impeller 21b, the harder the impeller 21b and the smaller the correction coefficient B. The correction coefficient B can be expressed, for example, by the following formula (3). The Vickers hardness is specified by the design information of the impeller 21b. Correction coefficient B = 4 × 10 7 (Vickers hardness) -3.0 ··· (3)

[0037] The correction coefficient C is a coefficient for correcting the particle size of the droplets. The correction coefficient C can be expressed, for example, by the following formula (4). Correction coefficient C = -7 × 10 -11 (Droplet particle size) 4 + 1 × 10 -7 (Droplet particle size) 3 - 4 × 10 -5 (Droplet particle size) 2 + 8.4 × 10 -3 (Droplet particle size) ··· (4)

[0038] The correction coefficient D is a coefficient for correcting the collision velocity. The correction coefficient D can be expressed, for example, by the following formula (5). Correction coefficient D = 4 × 10 -21 (Collision velocity) 7.6 ··· (5)

[0039] The correction coefficient E is a coefficient for correcting the surface roughness of the impeller 21b. The correction coefficient E can be expressed, for example, by the following formula (6). The surface roughness is specified by the design information of the impeller 21b. Correction coefficient E = 2 × 10 -4 (Surface roughness) 3-1.3 × 10 -2 (Surface roughness) 2 +3.2 × 10 -1 (Surface roughness) + 7.4 × 10 -1 ...(6)

[0040] The ECU 100 estimates the amount of erosion and predicts the lifespan of the compressor 21 (step S6). For example, the ECU 100 checks the amount of erosion over time and predicts the date or mileage at which the plating on the impeller 21b disappears as the lifespan of the compressor 21. Once the ECU 100 has predicted the lifespan of the compressor 21, it outputs a replacement urge signal (step S7) and terminates the process.

[0041] This allows the aforementioned vehicle management personnel to check the lifespan of the compressor 21 included in the replacement prompt signal, and if they determine that the lifespan is below the threshold lifespan, they can contact the vehicle dealership to prompt the replacement of the supercharger 20 before the impeller 21b fails.

[0042] As described above, according to this embodiment, the vehicle 10 is equipped with a supercharger 20. The supercharger 20 includes a compressor 21 and a turbine 22. The compressor 21 is equipped with an impeller 21b that rotates based on the intake air directed toward the engine 11. The turbine 22 is equipped with a wheel 22b that rotates integrally with the impeller 21b. The vehicle 10 is also equipped with an EGR passage 56 that recirculates a portion of the exhaust gas from the engine 11 flowing downstream of the exhaust passage of the turbine 22 as EGR gas to the upstream of the intake passage of the compressor 21.

[0043] The ECU 100 predicts the lifespan of the compressor 21 in such a vehicle 10. Specifically, the ECU 100 calculates the amount of condensate based on EGR gas, based on weather data representing the weather at the location where the vehicle 10 is traveling and moisture data representing the amount of moisture generated when the fuel supplied to the engine 11 is burned. The ECU 100 also calculates the particle size of the condensate droplets based on a three-dimensional particle size map information that defines the relationship between the amount of condensate, the vehicle speed of the vehicle 10, and the intake air volume of the supercharger 20. Furthermore, the ECU 100 predicts the lifespan of the compressor 21 based on the droplet diameter, the collision velocity of the droplets with the impeller 21b according to the turbo rotation speed of the supercharger 20, and the design information of the impeller 21b. In this way, the ECU 100 can predict the lifespan of the compressor 21.

[0044] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0045] For example, a miniature high-speed camera may be installed near the inlet of the compressor 21, and the droplets may be imaged in real time using the miniature high-speed camera. Based on the state of the droplets, the particle size, number, and collision velocity of the condensed water droplets may be calculated. [Explanation of Symbols]

[0046] 10 vehicles 11 Engine 12 Intake passage 20 Supercharger 21 Compressor 21b Impeller 22 Turbines 22b wheels 30 Exhaust passage 56 EGR passage 64. In-vehicle communication device 65 Weather Database Server 100 ECU

Claims

[Claim 1] A life prediction device for predicting the life of a compressor in a vehicle comprising: a compressor including an impeller that rotates based on intake air directed toward the engine; a turbocharger including a wheel that rotates integrally with the impeller; and an EGR (Exhaust Gas Recirculation) passage that recirculates a portion of the exhaust gas from the engine flowing downstream of the turbine's exhaust passage to the upstream of the compressor's intake passage as EGR gas, the device predicts the life of the compressor. A first calculation means calculates the amount of condensed water based on the EGR gas, based on first data representing the weather at the location where the vehicle is traveling and second data representing the amount of water generated by the combustion of fuel supplied to the engine. A second calculation means calculates the diameter of the condensate droplets based on predetermined information that defines the relationship between the amount of condensate, the vehicle speed, and the intake air volume of the supercharger. A prediction means for predicting the lifespan based on the diameter of the droplet, the collision velocity of the droplet with the impeller according to the rotational speed of the supercharger, and the design information of the impeller. A life prediction device characterized by having the following features.

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