JP4715941B2 - Vehicle diagnostic device - Google Patents

Description

  The present invention relates to a diagnosis device for a vehicle driven by an internal combustion engine, and more particularly to a device for diagnosing the fuel consumption of a vehicle.

  Various methods have been proposed for calculating the fuel consumption of a vehicle, particularly a vehicle driven by an internal combustion engine. For example, Japanese Patent Application Laid-Open No. 2004-60548 discloses a method for calculating fuel consumption using a fuel consumption rate map that defines the relationship among the rotational speed, torque, and fuel consumption rate of an internal combustion engine. According to this method, the correction rate of the current fuel consumption rate with respect to the initial fuel consumption rate of the internal combustion engine is obtained from the travel distance, and the fuel consumption rate map is obtained by multiplying each value stored in the fuel consumption rate map by the fuel consumption rate correction rate. It is corrected. The fuel consumption rate of the internal combustion engine is calculated by referring to the corrected fuel consumption rate map based on the rotation speed and torque of the internal combustion engine, and the fuel consumption amount of the internal combustion engine is calculated based on the calculated fuel consumption rate.

JP 2004-60548 A JP-A-1-290967

  However, what can be calculated by the method disclosed in Japanese Patent Application Laid-Open No. 2004-60548 is only the fuel consumption for evaluating the driving state of the vehicle by the driver, not the fuel consumption for diagnosing the state of the vehicle. The fuel consumption changes not only when the driver is driving the vehicle, but also when the vehicle state changes, such as when the internal combustion engine deteriorates due to changes over time. In this case, the relationship between the engine speed, torque and fuel consumption rate of the internal combustion engine changes, but the relationship is fixed in the method disclosed in Japanese Patent Application Laid-Open No. 2004-60548. The fuel consumption rate is corrected by the correction rate according to the travel distance, but the relationship between the travel distance and the correction rate is fixed and reflects the actual state of the vehicle. Absent.

  In order to diagnose the state of the vehicle, it is necessary to calculate the fuel consumption reflecting the actual state of the vehicle, particularly the internal combustion engine. For that purpose, it is important to update the map data used for the calculation of fuel consumption appropriately, but there is one problem here.

  First, the map data used for calculating the fuel consumption is preferably one in which the fuel consumption is associated with the torque of the internal combustion engine and the engine speed. However, the relationship varies depending on the values of engine parameters used for controlling the internal combustion engine. A typical one of such engine parameters is the ignition timing. If the values of other engine parameters are constant, the torque becomes maximum when the ignition timing is MBT, and as a result, the fuel consumption is also optimal. Since the control of the internal combustion engine is performed so as to realize the MBT operation as much as possible, the map data is obtained by associating the fuel consumption with the torque and the engine speed when the ignition timing is MBT. It is desirable to be. If the map data is based on MBT, it is desirable that the update timing of the map data is also when the internal combustion engine is operating at MBT.

  However, depending on the driving state of the vehicle by the driver, the operation of the internal combustion engine is often performed at an ignition timing other than MBT. For this reason, if the update timing of the map data is limited to when it is operated by MBT, there is a possibility that the update cannot be performed with sufficient frequency. If the update frequency is low, the actual state of the internal combustion engine cannot be sufficiently reflected in the map data, and as a result, accurate diagnosis based on fuel consumption cannot be performed.

  The present invention has been made in order to solve the above-described problems, and eliminates the possibility that the driver updates the map data used for calculating the fuel consumption by the driving state of the vehicle. An object of the present invention is to provide a vehicle diagnostic apparatus that can sufficiently reflect the actual state of the internal combustion engine in the calculation result of the fuel consumption by efficient updating.

In order to achieve the above object, the first invention calculates the fuel consumption under the actual or assumed driving pattern using map data in which the fuel consumption is associated with the torque and engine speed of the internal combustion engine. In the vehicle diagnostic device,
Torque characteristic model storage means for storing a torque characteristic model representing a relationship between a specific engine parameter and torque used for controlling the internal combustion engine;
Data acquisition means for acquiring each value of the fuel consumption, torque and engine speed at that time and the value of the specific engine parameter when the update timing of the map data has arrived,
When the acquired value of the specific engine parameter is different from the specific value, an update torque value generation for generating an update torque value corresponding to the specific value from the acquired torque value using the torque characteristic model Means,
Map data update for updating the fuel consumption value of the map data corresponding to the acquired torque value or the generated updating torque value and the acquired engine speed value with the acquired fuel consumption value Means,
It is characterized by having.

According to a second invention, in the first invention,
The specific engine parameter is an ignition timing, and the specific value is MBT.

According to a third invention, in the first or second invention,
The map data updating means stores the acquired fuel consumption value in association with the torque and engine speed values, and a prescribed number of fuel consumption values corresponding to the same torque and engine speed values are acquired. Then, the fuel consumption value of the map data is updated with the average value of the fuel consumption for the prescribed number.

  According to the first aspect, when the map data update timing arrives, the values of the fuel consumption, torque, and engine speed and the value of the specific engine parameter at that time are respectively acquired. Then, the fuel consumption value of the map data corresponding to the acquired torque value and the acquired engine speed value is updated with the acquired fuel consumption value. However, if the acquired value of the specific engine parameter is different from the specific value, the torque characteristic model representing the relationship between the specific engine parameter and the torque is used to update the value corresponding to the specific value from the acquired torque value. Torque values are generated. Then, the fuel consumption value of the map data corresponding to the generated torque value for updating and the acquired engine speed value is updated with the acquired fuel consumption value. As described above, according to the first aspect, the map data can be updated every time the update timing of the map data comes regardless of whether the value of the specific engine parameter is a specific value. Thus, the actual state of the internal combustion engine can be sufficiently reflected in the calculation result of the fuel consumption.

  According to the second aspect of the invention, since the maximum fuel consumption that can be achieved when the internal combustion engine is operated by MBT can be calculated, the vehicle can be diagnosed fairly with respect to the fuel consumption. The map data is premised on MBT, but even if it is data acquired when the internal combustion engine is operated at an ignition timing other than MBT, it can be used for updating map data. The timing is not limited to when operating in MBT.

  According to the third aspect of the invention, a prescribed number of fuel consumption values corresponding to the same torque and engine speed values are acquired, and for updating the fuel consumption value in the map data, fuel for the prescribed number is obtained. Since the average value of consumption is used, the influence of noise contained in the acquired data can be reduced and the update accuracy can be increased.

It is the schematic which shows the structure of the diagnostic apparatus of the vehicle as embodiment of this invention. It is a conceptual diagram of the fuel consumption map concerning embodiment of this invention. It is a conceptual diagram of the torque characteristic model concerning embodiment of this invention. It is a flowchart which shows the procedure of the update of the fuel consumption map implemented in embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.

  A vehicle to be diagnosed in the present embodiment is a vehicle driven by an internal combustion engine (hereinafter simply referred to as an engine). The engine provided in the vehicle is a spark ignition type engine in which the air-fuel ratio is controlled to stoichiometric. Other engine specifications are not limited. The diagnostic device of the present embodiment is realized as one function of a control device provided in such a vehicle. FIG. 1 is a block diagram showing the configuration when the vehicle control device functions as a diagnostic device. The configuration shown in FIG. 1 is a configuration that is virtually realized by the CPU of the control device operating according to a program stored in the memory of the control device.

  One of the elements constituting the diagnostic device of the present embodiment is a travel mode data storage unit 2 that stores travel mode data for diagnosis. The driving mode data is a diagnostic driving pattern defined by the vehicle speed. Specific examples of the travel pattern include travel patterns defined in the 10.15 mode or the US LA4 mode. The driving mode data stored in the driving mode data storage unit 2 can be rewritten from the outside.

  The fuel consumption calculation unit 4 is included in the components of the diagnostic apparatus. The fuel consumption calculation unit 4 calculates the fuel consumption of the vehicle using a fuel consumption model. The fuel consumption model is a calculation model for calculating the fuel consumption from the driving mode data. Hereinafter, the fuel efficiency X [km / l] calculated by the fuel efficiency model is referred to as mode fuel efficiency. The fuel consumption model is composed of a drive system model and a fuel consumption map. In the fuel consumption map, the fuel consumption q [g / s] is associated with the engine speed Ne [rpm] and the engine torque (shaft torque) Te [Nm]. The drive train model is a model of torque and rotation transmission characteristics from the engine to the tire. By calculating the drive system model from the reverse direction, the engine speed Ne and the torque Te can be calculated backward from the travel mode data. Various data composing the drive system model, specifically vehicle specifications such as vehicle weight and tire diameter, various loss factors such as rolling friction coefficient, transmission shift pattern data, etc. can be rewritten from the outside. ing.

The calculation of the mode fuel consumption X using the drive system model and the fuel consumption map is performed as follows. First, driving mode data is read from the driving mode data storage unit 2 into the fuel consumption calculation unit 4. The fuel consumption calculation unit 4 acquires the vehicle speed V [m / s] from the driving mode data at a predetermined time interval (for example, every 1 second), and calculates the acceleration α [m / s ² ] from the vehicle speed V. Then, the calculated vehicle speed V and acceleration α are input to the drive system model.

In the drive system model, the running resistance R _all [N] is calculated based on the vehicle speed V and the acceleration α. The running resistance R _all can be calculated as the sum of the air resistance R _air and the rolling resistance R _roll . Each of the resistance values R _air and R _roll is calculated by a map created by experiment in advance or by using a physical formula. Subsequently, the tire rotation speed Na [rpm] is calculated from the vehicle speed V and the effective radius R of the tire, and the tire torque Ta [Nm] is calculated from the running resistance R _all and the effective radius R of the tire.

  Next, in the drive system model, the propeller shaft rotational speed Np [rpm] is calculated from the tire rotational speed Na, and the propeller shaft torque Tp [Nm] is calculated from the tire torque Ta. In these calculations, the differential gear differential ratio and the torque loss in the differential gear are taken into account. Then, the engine speed Ne [rpm] is calculated from the propeller shaft speed Np, and the engine torque Te [Nm] is calculated from the propeller shaft torque Tp. These calculations take into account the transmission gear ratio and various torque losses.

  By performing the calculation according to the procedure as described above, the engine torque Te and the engine speed Ne when the vehicle is driven in the driving pattern defined by the driving mode data are calculated at predetermined time intervals.

  The fuel consumption calculation unit 4 applies the engine torque Te and the engine speed Ne calculated by the drive system model to the fuel consumption map. As a result, the fuel consumption q [g / s] is calculated every predetermined time interval (here, every second) from the start to the end of the travel pattern defined by the travel mode data. Finally, the fuel consumption calculation unit 4 calculates the mode fuel consumption X using the time integral value of the vehicle speed V and the time integral value of the fuel consumption q. The integration interval of each time integration is from the start point to the end point of the driving pattern defined by the driving mode data.

  The diagnostic apparatus includes a fuel consumption OBD unit 6 as a component. The fuel consumption OBD unit 6 performs fuel consumption diagnosis based on the mode fuel consumption calculated using the fuel consumption model. The mode fuel efficiency calculated using the fuel efficiency model is a fuel efficiency determined by the state of the vehicle itself, and is a fair fuel efficiency evaluation index that is not affected by the use state of the vehicle or the driving state of the driver. Therefore, when the mode fuel efficiency is deteriorated, there is a possibility that some problem has occurred in the vehicle. Therefore, when it is determined by the fuel economy diagnosis that the mode fuel efficiency has deteriorated, the fuel efficiency OBD unit 6 issues a warning to the driver using a warning lamp in the vehicle interior (not shown), and the vehicle is inspected and maintained. Prompt.

Further, the map data update unit 8 is included in the components of the diagnostic apparatus. The map data update unit 8 updates the fuel consumption map at a predetermined cycle. FIG. 2 is a conceptual diagram of a fuel consumption map. As shown in this figure, the map data update unit 8 acquires the engine speed Ne and the MBT torque T _{MBT of the} engine, and updates the value of the fuel consumption specified by them to the value q acquired this time. The MBT torque is a torque output from the engine when the ignition timing is MBT. If the engine speed and the fuel consumption are the same, the torque becomes maximum when the ignition timing is MBT, and as a result, the fuel consumption is also optimal. Therefore, in the fuel consumption map shown in FIG. 2, the fuel consumption is associated with the engine torque and the rotational speed when the ignition timing is MBT.

  The map data update unit 8 acquires data used for updating the fuel consumption map from the actual control result of the engine. However, the engine is not necessarily operated by MBT. From the viewpoint of fuel consumption, the engine is preferably operated at MBT as much as possible. However, in practice, the engine is often operated at an ignition timing other than MBT. For this reason, if the update of the fuel consumption map is limited when the ignition timing is MBT, the update cannot be performed with sufficient frequency.

Therefore, when the ignition timing is other than MBT, the map data update unit 8 converts the acquired torque into MBT torque, and updates the fuel consumption map using the converted MBT torque. A torque characteristic model is used for the conversion. The torque characteristic model used in the present embodiment is a statistical model that expresses the relationship between the ignition timing and the torque by a mathematical expression. When the engine speed is constant, the statistical model can be expressed by the following equation. In the following formula, a, b and c are constants and are identified from the experimental results. A statistical model represented by the following formula prepared for each engine speed can also be referred to as a torque characteristic model according to the present embodiment.
F (SA) = a * SA ² + b * SA + c

The torque characteristic model is stored in the map data update unit 8. FIG. 3 is a conceptual diagram of a torque characteristic model stored in the map data update unit 8. The torque curve shown in the figure is a torque characteristic model. As shown in this figure, the ignition timing obtained in the update timing of the fuel consumption map in SA, and torque at that time was T _SA. Also assume that the fuel consumption at that time is q. Then, on the torque curve which is specified by the ignition timing SA and the torque _{T SA,} torque corresponding to the MBT it is assumed to be _{T MBT.} Since the present embodiment is premised on stoichiometric operation, the fuel consumption value is the same anywhere on the torque curve, and the fuel consumption q required to generate the torque T _SA at the ignition timing SA The fuel consumption required to generate the torque T _{MBT in the MBT} is equal. The map data update unit 8 updates the value of the fuel consumption specified by the engine speed Ne and the torque T _MBT to the value q acquired this time.

  However, the learning by the map data updating unit 8 is performed only when the engine is in a normal control state. The normal control state means a state where no special control is performed. Special control here means control in which the aforementioned torque characteristic model cannot be used to represent the relationship between ignition timing and torque. For example, a rich operation or a lean operation in which the air-fuel ratio is positively removed from the stoichiometry is included in the special control. In addition, the control for fixing the valve timing performed at the cold start to a specific position is also included in the special control. This is because the torque characteristic model is based on the premise that the valve timing is controlled according to the course. Further, special control includes catalyst warm-up operation that intentionally retards the ignition timing.

  FIG. 4 is a flowchart showing the procedure for updating the fuel consumption map described above. In the first step S2 of the fuel consumption diagnosis, when the update timing of the fuel consumption map has arrived, the map data update unit 8 is instructed to update the fuel consumption map. The update timing can be measured by the distance traveled since the previous update. Or you may measure an update timing with the elapsed time from the last update.

  In the next step S4, various data in the current operating state is acquired. The data acquired here are the engine speed Ne, the ignition timing SA, the engine torque Te, and the fuel consumption q. Among these, regarding the engine torque Te, if the engine includes a torque sensor, an actual value measured by the torque sensor is acquired. In an engine that does not include a torque sensor, if any of the cylinders has an in-cylinder pressure sensor, an estimated torque calculated based on the in-cylinder pressure is acquired.

  In the next step S6, it is determined whether or not the current ignition timing SA is MBT. If the current ignition timing SA is MBT, the process proceeds to step S10. In step S10, the fuel consumption value specified by the current engine speed Ne and torque Te on the fuel consumption map is updated to the value q acquired this time.

If the current ignition timing is not MBT, the process proceeds to step S10 after step S8. In step S8, torque T _{MBT in MBT} is estimated using the torque characteristic model. In the subsequent step S10, the value of the fuel consumption specified by the current engine speed Ne and the estimated MBT torque T _MBT on the fuel consumption map is updated to the value q acquired this time.

  As described above, according to the diagnostic device of the present embodiment, the fuel consumption map can be updated every time the fuel consumption map update timing comes regardless of whether the ignition timing is MBT. Therefore, the update timing of the fuel consumption map is not limited to when operating in MBT, and the actual state of the engine can be sufficiently reflected in the calculation result of the fuel consumption by the efficient update of the fuel consumption map. .

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications can be made.

  In the above-described embodiment, the fuel consumption map is updated based on the current fuel consumption data acquired when there is an update instruction. Actually, there is a variation in the actual measurement value of the fuel consumption, and therefore, there is a possibility that an error will be included if the fuel consumption data is updated once. Therefore, preferably, the acquired fuel consumption value is stored in association with the torque and rotation speed values. When the fuel consumption values corresponding to the same torque and rotational speed values are acquired for a specified number of times (for example, 10 times), the fuel consumption map is updated with the average value of the fuel consumption data for the specified number of times. It is preferable to do this. By doing so, the influence of the noise contained in the acquired data can be reduced and the accuracy of updating the fuel consumption map can be increased.

  In the above-described embodiment, a torque characteristic model representing the relationship between the ignition timing and the torque is used. This is an example of a torque characteristic map according to the present invention, that is, a torque characteristic map representing a relationship between a specific engine parameter used for engine control and torque. The specific engine parameter is not limited to the ignition timing. The air-fuel ratio, the fuel injection timing in the direct engine, the EGR rate, the valve timing, etc. can be used as specific engine parameters, or all of them can be used as specific engine parameters. For example, if a specific engine parameter is an air-fuel ratio, the stoichiometric value can be set to a specific value. In this case, when the current air-fuel ratio is different from the stoichiometric value, an update torque value corresponding to the stoichiometric value is calculated from the acquired torque value using a torque characteristic model that represents the relationship between the air-fuel ratio and the torque. be able to.

2 Driving mode data storage unit 4 Fuel consumption calculation unit 6 Fuel consumption OBD unit 8 Map data update unit

Claims (3)

In a vehicle diagnostic apparatus that calculates fuel consumption under an actual or assumed driving pattern using map data in which fuel consumption is associated with torque and engine speed of an internal combustion engine,
Torque characteristic model storage means for storing a torque characteristic model representing a relationship between a specific engine parameter and torque used for controlling the internal combustion engine;
Data acquisition means for acquiring each value of the fuel consumption, torque and engine speed at that time and the value of the specific engine parameter when the update timing of the map data has arrived,
When the acquired value of the specific engine parameter is different from the specific value, an update torque value generation for generating an update torque value corresponding to the specific value from the acquired torque value using the torque characteristic model Means,
Map data update for updating the fuel consumption value of the map data corresponding to the acquired torque value or the generated updating torque value and the acquired engine speed value with the acquired fuel consumption value Means,
A vehicle diagnostic apparatus comprising:   2. The vehicle diagnostic apparatus according to claim 1, wherein the specific engine parameter is an ignition timing, and the specific value is MBT.   The map data updating means stores the acquired fuel consumption value in association with the torque and engine speed values, and a prescribed number of fuel consumption values corresponding to the same torque and engine speed values are acquired. 3. The vehicle diagnostic apparatus according to claim 1, wherein the fuel consumption value of the map data is updated with an average value of the fuel consumption of the prescribed number.

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