JP2009162141A - Fuel property estimation device - Google Patents

Abstract

A fuel property relating to a fuel mixed with alcohol is accurately estimated.
In a hybrid vehicle, when an engine capable of using an ethanol mixed fuel is started, ECU 100 executes start control, and appropriately estimates the fuel property of the fuel. At this time, the cranking rotational speed NEkr in the cranking period until the engine 200 reaches the initial explosion state is acquired as an index value that defines the friction of the engine 200. On the other hand, torque assist by MG1 is continued in the assist period after the first explosion until reaching the complete explosion state, and the degree of torque assist at this time is greatly influenced by the fuel property. The ECU 100 acquires the length of the assist period as the degree of torque assist, and estimates the fuel property based on the cranking rotational speed NEkr and the length of the assist period.
[Selection] Figure 4

Description

  The present invention relates to a technical field of a fuel property estimation device for estimating a fuel property in an internal combustion engine capable of using a fuel mixed with alcohol.

  As an apparatus for estimating fuel properties, an apparatus that uses a complete explosion start time, which is a time from when an internal combustion engine is started to when a complete explosion is started, has been proposed (for example, Patent Document 1). According to the fuel property determination device and the internal combustion engine control device (hereinafter referred to as “conventional technology”) disclosed in Patent Document 1, the complete explosion start time is compensated by the starter power supply voltage value and the cooling water temperature. According to the fuel property parameter, which is obtained by adding the peak rotation speed arrival time, which is the time from the start of complete explosion until the internal combustion engine reaches its peak, with the starter power supply voltage value and the cooling water temperature. It is said that it is possible to accurately determine the fuel properties.

  In addition, a technique for determining the fuel property based on the detection result of the torque detection means when the engine speed is maintained in a predetermined region has been proposed (see, for example, Patent Document 2).

  In addition, a technique for estimating the alcohol concentration by comparing the torque reaction force detected from the motor generator with a reference torque has been proposed (see, for example, Patent Document 3).

JP-A-6-307283 JP 2005-343458 A JP 2007-137321 A

  The above-described complete explosion start time in the prior art is the time from the start of the internal combustion engine to the complete explosion and cranking by the starter, in other words, the time during which the internal combustion engine cannot rotate independently. Therefore, the complete explosion start time is significantly influenced not only by the fuel properties but also by the friction of the internal combustion engine. In the conventional technology, the influence of these multiple factors on the complete explosion start time has not been separated, and when the complete explosion start time is compensated by the starter power supply voltage and the cooling water temperature, the peak rotation is further improved. It is difficult to accurately grasp the fuel property when the arrival time is compensated with the value or the value obtained by adding them is used as the fuel property parameter. In addition, the conventional technology does not assume the use of a fuel in which alcohol is mixed as a fuel. However, when this type of fuel is used, the combustion performance is greatly affected by the mixed state of the alcohol. It is obvious that estimation of fuel properties becomes more difficult. That is, the conventional technique has a technical problem that it is difficult to accurately estimate the fuel properties of the fuel mixed with alcohol.

  This invention is made | formed in view of the problem mentioned above, and makes it a subject to provide the fuel property estimation apparatus which can estimate the fuel property which concerns on the fuel with which alcohol was mixed correctly.

  In order to solve the above-described problems, a fuel property estimation device according to the present invention includes an internal combustion engine that can use fuel mixed with alcohol, and assist means that can assist torque including cranking for the internal combustion engine. An apparatus for estimating a fuel property related to the fuel in a vehicle equipped with the assist means and the internal combustion engine so that the internal combustion engine reaches a predetermined complete explosion state with the assist when the internal combustion engine is started Control means for controlling the engine, first specifying means for specifying the degree of friction of the internal combustion engine, and an assist period from when the internal combustion engine reaches a predetermined initial explosion state until it reaches the complete explosion state. A second specifying means for specifying the degree of assistance in at least a part, and based on the specified degree of friction and assistance. Characterized by comprising the estimating means for estimating the fuel property Te.

  The “internal combustion engine” according to the present invention includes at least one cylinder, and power generated when fuel is burned (preferably, a mixture of fuel and air is burned) in each of the cylinders, for example, a piston, It is an engine that can be taken out as a driving force of a vehicle through various physical or mechanical transmission paths such as a connecting rod and a crankshaft. In the present invention, various alcohols such as ethanol are mixed as a fuel. It is a concept that encompasses an engine that is configured to be able to use a fuel that is made (hereinafter, referred to as “alcohol mixed fuel” as appropriate).

  Here, the “alcohol mixed fuel” is, for example, a mixture of gasoline and alcohol as a preferred form, and the mixing ratio is not particularly limited in the present invention. That is, the alcohol-mixed fuel according to the present invention is intended to take a value from 0% to 100% as the alcohol concentration (which may be weight concentration or volume concentration). Further, the alcohol mixed fuel may be taken into a storage means such as a fuel tank as an alcohol mixed fuel at the time of refueling, for example, or taken into a storage means different from a storage means for a mixture such as gasoline. When fuel is supplied to the engine, it may be mixed appropriately.

  On the other hand, the vehicle according to the present invention including the internal combustion engine according to the present invention includes assist means as a concept that includes means capable of assisting torque with respect to the internal combustion engine. Here, “torque assist” refers to torque for physically driving the internal combustion engine in a situation where the internal combustion engine does not spontaneously output torque in addition to assisting the torque output by the internal combustion engine. It is a concept that includes cranking to supply.

  Within the scope of such a concept, the configuration of the assist means, in particular its physical, mechanical, mechanical or electrical configuration, is not limited at all, and the assist means is mainly used for cranking, for example as a preferred form. A starter motor or a motor or a motor generator having a relatively large rating and physique used as a driving force source for a vehicle together with an internal combustion engine may be used. Further, the configuration for supplying the torque for assisting the torque (hereinafter referred to as “assist torque” as appropriate) to the internal combustion engine is not limited as long as the assist of the torque is possible. The rotating shaft of the assist means may be configured to be coaxial with the rotating shaft of the internal combustion engine, and the assist means is connected to the internal combustion engine via, for example, various shaft bodies, various gears, a gear mechanism, a gear device, a gear system, and the like. It may be connected.

  According to the fuel property estimation device of the present invention, during its operation, control means that can take the form of various processing units such as an ECU (Electronic Control Unit), various controllers or various computer systems such as a microcomputer device, etc. However, when the internal combustion engine is started, the assist means and the internal combustion engine are controlled so that the internal combustion engine reaches a predetermined complete explosion state with the assist described above.

  Here, “at the time of starting” is, as a preferred form, for example, various inputs for starting the internal combustion engine (for example, when the driver operates the ignition key, or the start button is physically pressed or wirelessly operated). This is a concept encompassing the timing at which an internal combustion engine in a physically stopped state is to be started.

  The “complete explosion state” according to the present invention means that at least the application of the assist torque is not theoretically, substantially or practically required, the combustion stability, the rotational fluctuation or the torque when the application of the assist torque is stopped. It is a concept that includes a state in which a malfunction such as fluctuation does not manifest at least to the extent that it cannot be overlooked in practice or does not misfire when the application of assist torque is stopped. More specifically, for example, an engine of an internal combustion engine The rotation speed refers to a state where the rotation speed reaches a preset target rotation speed, such as an independent rotation speed or an idle rotation speed equal to or higher than the self-rotation speed.

  That is, the application of the assist torque under the control of the control means includes cranking that forcibly drives the internal combustion engine that is physically stopped, and is preferably interlocked with the cranking. Continue to the internal combustion engine that has undergone the first explosion after the internal combustion engine operation control (for example, control of intake air amount, fuel injection amount, ignition timing or intake or exhaust valve timing, working angle or lift amount, etc.) It is done.

  According to the fuel property estimation device of the present invention, the internal combustion engine is in a predetermined initial explosion state by the second specifying means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. The degree of assist through the assist means in at least a part of the assist period from reaching to the complete explosion state described above is specified. Note that the “predetermined initial explosion state” is a state in which cranking is performed through the application of assist torque by the assist means and the first explosion is reached in the process of controlling the internal combustion engine described above. Including the state of having experienced several explosions to the extent that it does not significantly affect the estimation accuracy of fuel properties, which will be described later, at least practically. In general, the initial explosion state is a state of the internal combustion engine in the vicinity of where some torque starts to be generated in time series at the time of starting. Note that, during the cranking period before the initial explosion state, if the assist torque applied through the assist means is constant, the engine speed of the internal combustion engine becomes a substantially constant value that balances the friction of the internal combustion engine. Can converge. Therefore, before and after the first explosion, the engine speed of the internal combustion engine is at least a change that does not make it difficult to detect, preferably a relatively significant change, and whether the internal combustion engine has reached the initial explosion state. Judgment on refusal does not involve undue difficulty at least in practice.

  Here, the degree of assist (i.e., the degree of application of assist torque) from when the initial explosion state is reached to when the complete explosion state is reached is the concentration of alcohol in the fuel or whether the fuel is heavy or light, etc. It is greatly influenced by the fuel property of the internal combustion engine that includes such a concept.

  For example, if the fuel is relatively heavy, the combustibility including the ignitability of the fuel is relatively lowered. Therefore, if at least various conditions that define the complete explosion state are substantially unchanged, the internal combustion engine The degree of assist required to reach the complete explosion state increases, and conversely, if the fuel is light, the combustibility increases relatively, so the degree of assist is small. Further, in view of the fact that the latent heat of vaporization of alcohol causes a decrease in combustion temperature (this decrease in combustion temperature is accompanied by various advantages such as knocking suppression in the operation of a normal internal combustion engine), the concentration of alcohol in the fuel Is relatively high, at least at the time of start-up, the combustibility of the internal combustion engine is somewhat impaired, and the degree of assist required to bring the internal combustion engine to a complete explosion state increases. If it is relatively low, the degree of assist may be small. Therefore, the fuel property can be suitably estimated based on the degree of assist in the assist period from the first explosion to the complete explosion.

  Note that “specific” in the present invention refers to, for example, detecting a specific target directly or indirectly as a physical numerical value or an electrical signal corresponding to the physical numerical value via some detection means, or any detection means. Corresponding numerical values from maps etc. stored in appropriate storage means etc. based on physical numerical values detected in the form of electrical signals etc. directly or indirectly via the Selecting, deriving from such physical numerical values or selected numerical values in accordance with a preset algorithm or calculation formula, or the numerical values detected, selected or derived in this way, for example, electrical signals, etc. It is a broad concept encompassing simply acquiring in the form of. Within the scope of the concept, the second specifying means, for example, the length of the assist period, the amount of energy input during the assist period (for example, power or the amount of power), the value of the assist torque in the assist period, or The degree of assist may be specified as the engine speed or the like.

  The degree of assistance required to reach the complete explosion state from the initial explosion state, which is specified by the second specifying means, does not affect the fuel property at least on the cranking itself (the length of the cranking period is affected). In view of the above, the fuel property clearly has a high correlation with at least the degree of assist during the period from the start of cranking to the complete explosion of the internal combustion engine. It is effective as an index for estimating properties.

  On the other hand, the degree of assist from the first explosion to the complete explosion is also affected by the friction of the internal combustion engine. For example, if the fuel has a fuel property corresponding to high combustibility, if the friction of the internal combustion engine is large, a relatively large assist torque is required after the first explosion, Assuming that the fuel has a fuel property corresponding to low combustibility, if the friction of the internal combustion engine is small, the assist torque required after the first explosion can be small. Therefore, when the friction of the internal combustion engine is not taken into consideration, the fuel property estimated based on the degree of the assist, apart from how much the friction can be changed in practice within the range that the internal combustion engine can take as its actual use environment, At least some significant error can be included as an uncertainty factor.

  In order to deal with such a problem, according to the fuel property estimation device according to the present invention, when the internal combustion engine is started under the control of the control means, for example, various processing units such as ECU, various controllers, various computer systems such as a microcomputer device, etc. The degree of friction of the internal combustion engine is specified by the first specifying means that can take the above-described form. Here, the “degree of friction” according to the present invention can vary depending on, for example, the viscosity resistance of the lubricating oil, the circulation supply state, etc., for example, transmission members for various driving forces such as pistons, connecting rods and crankshafts, and the like. It refers to the degree of physical or mechanical frictional resistance of various sliding parts of an internal combustion engine including various bearings that support them as a preferred form.

  Such a degree of friction, for example, as an index value that can be changed stepwise or continuously, directly represents the degree of this kind of friction, or indirectly represents the degree of this kind of friction (i.e., friction). Specified as various index values). The configuration of the first specifying means is not limited as long as the degree of this type of friction can be specified to such an extent that the estimation accuracy related to the estimation of the fuel property can be secured at least in practice.

  According to the fuel property estimation device according to the present invention, the specified degree of friction and the degree of assist are determined by estimation means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device. Based on the above, the fuel property is estimated. In this case, the mode of estimating the fuel property based on each of these indices is not limited at all, but as a preferred form, the estimation means is preliminarily experimentally, empirically, theoretically or based on simulation, The fuel property may be estimated based on the correspondence relationship between the index value and the value defining the fuel property, which is given at least accuracy that is not insufficient in practice. This type of correspondence may be stored in the appropriate storage means in a pre-mapped form, or may be stored in the appropriate storage means in the form of a numerical arithmetic expression, a numerical operation algorithm, or the like.

  As described above, according to the fuel property estimation device according to the present invention, based on the degree of assist in the assist period from reaching the initial explosion state to reaching the complete explosion state while considering the friction of the internal combustion engine. Fuel properties can be estimated. That is, the fuel property can be accurately estimated by eliminating the influence of the friction on the assist level in the assist period.

  In one aspect of the fuel property estimation device according to the present invention, the estimation means estimates the fuel property based on the identified degree of friction and degree of assist when the internal combustion engine is cold-started. To do.

  According to this aspect, for example, when the internal combustion engine is started at a low temperature at which the above-described friction of the internal combustion engine can change to such an extent that the estimation accuracy of the fuel property cannot be practically overlooked, the degree of friction is considered. Is done. As a remarkable example, the friction of an internal combustion engine may vary depending on the temperature conditions inside and outside the vehicle that can define the viscous resistance of the lubricating oil, such as the outside air temperature, the cooling water temperature, or the lubricating oil temperature. Accordingly, at least when such a fuel property estimation accuracy can be affected at the time of cold start, or when the degree of friction is considered only in such a case, the present invention is concerned. The effect of the normal fuel estimation device appears more remarkably.

  In another aspect of the fuel property estimation device according to the present invention, the first specifying means may determine the degree of friction as the degree of the friction in at least a part of a cranking period until the internal combustion engine reaches the initial explosion state. Identify the operating conditions of the internal combustion engine.

  According to this aspect, the first specifying means specifies the operating condition of the internal combustion engine in at least a part of the cranking period as the degree of friction. As described above, the fuel property does not have a practically significant influence on the physical or mechanical driving state of the internal combustion engine in the cranking period in which combustion does not occur, and the operating condition of the internal combustion engine in the cranking period is It can be an index that significantly represents the influence of friction. That is, according to this aspect, it is possible to easily and accurately specify the friction of the internal combustion engine.

  In this aspect, the operating condition of the internal combustion engine in at least a part of the cranking period may be the engine speed of the internal combustion engine.

  The engine rotation speed is a constant value that balances with the friction of the internal combustion engine if at least the assist torque (in this case, cranking torque) applied from the assist means or the input energy (for example, input power) in the assist means is constant. Can converge. In any case, the engine speed is significantly affected by the friction of the internal combustion engine. Therefore, the value of the engine speed in at least a part of the cranking period is extremely effective in practice as an index value that defines the friction of the internal combustion engine.

  Further, in one aspect of the fuel property estimation device according to the present invention in which the degree of friction is specified based on the operating state of the internal combustion engine, a first correction that corrects the degree of friction according to the operating condition of the vehicle. Means for estimating the fuel property based on the corrected degree of friction.

  According to this aspect, the first correction means which can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device, for example, a VVT (Variable Valve Timing) or the like. Variable valve timing advance amount or lift amount of each valve (that is, a control amount that can cause a change in the compression reaction force of the internal combustion engine), input energy (for example, input power) or assist torque ( In other words, it has a practically significant influence on the identification of friction, such as the cranking torque in this case), or the outside air temperature, cooling water temperature or lubricating oil temperature, the index value that defines the lubrication state of the sliding part or the circulating supply state of the lubricating oil, etc. The degree of friction is corrected based on the driving conditions of the vehicle defined as what can be given. On the other hand, since the estimation means estimates the fuel property based on the corrected degree of friction, the estimation accuracy of the fuel property is ensured regardless of the driving conditions of the vehicle, which is useful in practice.

  The correction according to the first correction means may be made in a form that reflects these operating conditions after the degree of friction is specified, or the degree of friction as a part of the operation for specifying the degree of friction. It may be done at the same time as the identification. That is, the degree of friction specified by the first specifying means may have already undergone a process corresponding to a correction reflecting the driving conditions of this type of vehicle.

  In another aspect of the fuel property estimation apparatus according to the present invention, the second specifying means includes the length of the assist period, the engine speed of the internal combustion engine, and the degree of assist in at least a part of the assist period. At least one of index values defining the output state of the assist means is specified.

  According to this aspect, the length of the assist period, the engine rotation speed during the assist period, and the value of the assist torque that defines the output state of the assist means, for example, are specified. Therefore, the estimation means can be derived from these various index values that can have a high correlation with the fuel properties, for example, a value that defines the time transition of the engine speed or a reference value of a value that defines the time transition (for example, Deviation from the reference value of the assist torque, the value that defines the time transition of the assist torque or the reference value of the value that defines the time transition of the assist torque, and the time of energy for driving the assist means Based on the integrated value (that is, the product of the assist torque and the rotation speed), the fuel property can be estimated with high accuracy.

  In another aspect of the fuel property estimation apparatus according to the present invention, the fuel property estimation device further includes a second correction unit that corrects the fuel property in accordance with a driving condition of the vehicle.

  For example, the second correction means that can take the form of various processing units such as ECUs, various controllers or various computer systems such as microcomputer devices, etc., can improve the combustion performance in the internal combustion engine, such as ignition timing, intake air amount or fuel injection amount. Fuel properties depending on vehicle operating conditions that are regulated as things that can have a practically significant effect on the estimation of fuel properties, including prescribed operating conditions, assist torque provided by assist means or input energy in assist means, etc. Is corrected. Therefore, the fuel property can be estimated with high accuracy.

  The correction relating to the second correction means may be made in a form that reflects these operating conditions after the fuel property is estimated, or as a part of the operation for estimating the fuel property, It may be done at the same time. That is, the fuel property specified by the estimation means may have already undergone a process corresponding to a correction reflecting the driving conditions of this type of vehicle.

  In another aspect of the fuel property estimation device according to the present invention, the fuel property estimation device further includes a learning unit that learns the estimated fuel property, and the control unit is based on the learned fuel property at the time of the start after the next time. And controlling the internal combustion engine and the assist means.

  According to this aspect, the fuel properties estimated by the learning means that can take the form of various processing units such as an ECU, various controllers or various computer systems such as a microcomputer device, for example, experimentally and empirically in advance, The decision to update based on a judgment criterion set to regulate whether or not a significant change should be made in practice to the control conditions when starting the internal combustion engine theoretically or based on simulation etc. Since the learning value is reflected at the time of starting from the next time, for example, while using energy in the assist means as efficiently as possible. High practical benefits are provided, such as starting the internal combustion engine as quickly as possible.

  In another aspect of the fuel property estimation device according to the present invention, the vehicle includes at least one electric motor that functions as a driving force source of the vehicle together with the internal combustion engine and at least a part of which functions as the assist means. It is a vehicle.

  According to this aspect, in addition to the internal combustion engine, the vehicle is provided with at least one electric motor that can take the form of, for example, a motor or a motor generator as a driving force source, such as an inverter or various PCUs (Power Control Units). By means of various power controls such as current control, voltage control, or power control via at least the engine output shaft of the internal combustion engine, either directly or indirectly, depending on the discharge power from an energy source such as a battery The driving force can be output. Therefore, the torque assist according to the present invention can be realized at least in a range where there is no shortage in practice.

  Such an operation and other advantages of the present invention will become apparent from the embodiments described below.

<Embodiment of the Invention>
Various preferred embodiments of the present invention will be described below with reference to the drawings.

<Configuration of Embodiment>
<Configuration of hybrid vehicle>
First, with reference to FIG. 1, the structure of the hybrid vehicle 10 which concerns on one Embodiment of this invention is demonstrated. FIG. 1 is a block diagram of the hybrid vehicle 10.

  In FIG. 1, a hybrid vehicle 10 includes a speed reduction mechanism 11, an axle 12 and wheels 13, an ECU 100, an engine 200, a motor generator MG1 (hereinafter abbreviated as “MG1” where appropriate), and a motor generator MG2 (hereinafter referred to as “MG2” as appropriate). And a power split unit 300, a PCU (Power Control Unit) 400, a battery 500, and an SOC (State Of Charge) sensor 600.

  The speed reduction mechanism 11 is a gear mechanism that includes a differential gear (not shown) that is configured to be rotatable according to the power output from the engine 200 and the motor generator MG2. The vehicle can be decelerated according to a predetermined reduction ratio. The output shaft of the speed reduction mechanism 11 is connected to the axle 12, and the power of these power sources is configured to be transmitted to the axle 12 in a state where the rotational speed is reduced. The configuration of the speed reduction mechanism 11 is not limited as long as the driving force supplied from the engine 200 and the motor generator MG2 can be transmitted to the axle 11 while reducing the rotational speed of the shaft body based on the driving force. Instead, it may have a configuration that simply includes a differential gear or the like, and it is possible to obtain a plurality of gear ratios as a so-called reduction mechanism or transmission mechanism constituted by a plurality of clutches and brakes and a planetary gear mechanism. It may be configured.

  The axle 12 is a drive shaft for transmitting the driving force output from the engine 200 and the motor generator MG <b> 2 transmitted via the speed reduction mechanism 11 to the wheel 13.

  The wheel 13 is a drive wheel that transmits the power transmitted through the axle 12 to the road surface.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, and the like and is configured to be able to control the entire operation of the hybrid vehicle 10. It is an example of a “property estimation device”. The ECU 100 is configured to be able to execute start-up control described later according to a control program stored in the ROM. The ECU 100 includes the “control means”, “first specifying means”, “second specifying means”, “estimating means”, “first correcting means”, and “second correcting means” according to the present invention. And an integrated electronic control unit that functions as an example of each of the “learning means”. However, the physical, mechanical, and electrical configurations of these means according to the present invention are not limited to these, for example, You may comprise as various computer systems, such as several ECU, various processing units, various controllers, or a microcomputer apparatus.

  The engine 200 is a gasoline engine that is an example of an “internal combustion engine” according to the present invention, and functions as a main power source of the hybrid vehicle 10. The detailed configuration of the engine 200 will be described later.

  The motor generator MG1 is a motor generator as an example of “assist means” and “motor” according to the present invention, and further serves as a generator for charging the battery 500 or supplying power to the motor generator MG2. It is configured to function as an electric motor for assisting the driving force of engine 200.

  Motor generator MG2 is a motor generator that is another example of the “motor” according to the present invention, and is configured to function as a motor that assists the power of engine 200 or as a generator that charges battery 500. ing.

  The motor generator MG1 and the motor generator MG2 are configured as, for example, a synchronous motor generator, and include a rotor having a plurality of permanent magnets on the outer peripheral surface, and a stator wound with a three-phase coil that forms a rotating magnetic field. Prepare. However, other types of motor generators may be used.

  The power split mechanism 300 is a planetary gear mechanism configured to be able to distribute the output of the engine 200 to the MG 1 and the axle 12.

  Here, a detailed configuration of the power split mechanism 300 will be described with reference to FIG. FIG. 2 is a schematic diagram showing the relationship between the power split mechanism 300 and its peripheral portion. In the figure, the same reference numerals are given to the same portions as those in FIG. 1, and the description thereof will be omitted as appropriate.

  In FIG. 2, the power split mechanism 300 is arranged between a sun gear 303 provided at the center, a ring gear 301 provided concentrically on the outer periphery of the sun gear 303, and between the sun gear 303 and the ring gear 301. A plurality of pinion gears 305 that revolve while rotating on the outer periphery of 303 and a planetary carrier 306 that is coupled to an end portion of a crankshaft 205 to be described later and supports the rotation shaft of each pinion gear.

  Further, the sun gear 303 is coupled to a rotor (not shown) of MG1 via a sun gear shaft 304, and the ring gear 301 is coupled to a rotor (not shown) of MG2 via a ring gear shaft 302. The ring gear shaft 302 is connected to the axle 12, and the motive power generated by the MG 2 is transmitted to the axle 12 through the ring gear shaft 302, and similarly, the driving force from the wheels 13 transmitted through the axle 12. Is input to the MG 2 via the ring gear shaft 302.

  Under such a configuration, the power split mechanism 300 can transmit the power generated by the engine 200 to the sun gear 303 and the ring gear 301 by the planetary carrier 306 and the pinion gear 305 to split the power of the engine 200 into two systems. It is.

  Returning to FIG. 1, the PCU 400 converts the DC power extracted from the battery 500 into AC power, supplies the AC power to the motor generator MG1 and the motor generator MG2, and converts the AC power generated by the motor generator MG1 and the motor generator MG2 into DC power. This is a power control unit that includes an inverter, a boost converter, a DC-DC converter, and the like that can be converted into and supplied to the battery 500. Motor generator MG <b> 1 and motor generator MG <b> 2 are configured to be able to input / output electric power to / from battery 500 via PCU 400. Note that the PCU 400 is electrically connected to the ECU 100, and its operation state is controlled by the ECU 100 to the upper level.

  Battery 500 is a rechargeable storage battery configured to be able to function as a power supply source related to power for powering motor generator MG1 and motor generator MG2.

  The SOC sensor 600 is a sensor configured to be able to detect the SOC of the battery 500. The SOC sensor 600 is electrically connected to the ECU 100, and the SOC detected by the SOC sensor 600 is grasped by the ECU 100 constantly or at a constant or indefinite period.

  Here, the configuration of the engine 200 will be described with reference to FIG. FIG. 3 is a schematic configuration diagram conceptually showing the configuration of the engine 200.

  In FIG. 3, the engine 200 burns the air-fuel mixture through an ignition operation by an ignition device 202 in which a part of a spark plug (not shown) is exposed in a combustion chamber in a cylinder 201, and the explosive force due to such combustion. The reciprocating motion of the piston 203 that occurs in response to the above is converted into the rotational motion of the crankshaft 205 via the connecting rod 204. A crank position sensor 206 that detects the rotational position (ie, crank angle) of the crankshaft 205 is installed in the vicinity of the crankshaft 205. The engine 200 is an in-line four-cylinder engine in which four cylinders 201 are arranged in series in a direction perpendicular to the paper surface. However, since the configurations of the individual cylinders 201 are equal to each other, in FIG. Only the cylinder 201 will be described.

  In the engine 200, the air sucked from the outside passes through the intake pipe 207 and is mixed with the fuel injected from the injector 212 in the intake port 210 to become the above-mentioned air-fuel mixture. The fuel is stored in a fuel tank (not shown), and is pumped and supplied to the injector 212 via a delivery pipe (not shown) by the action of a feed pump (not shown). The form of the injection means for injecting the fuel does not have to adopt a so-called intake port injector configuration as shown in the figure. For example, the pressure of fuel pumped by a feed pump or other low-pressure pump is further increased by a high-pressure pump. It may have a form such as a so-called direct injection injector configured to be able to directly inject fuel into the high-temperature and high-pressure cylinder 201. In the present embodiment, the fuel stored in the fuel tank and injected from the injector 212 is an ethanol mixed fuel that is a mixed fuel of gasoline and ethanol (that is, an example of the “fuel mixed with alcohol” according to the present invention). The engine 200 is configured so that the ethanol concentration of the ethanol mixed fuel can take a value from 0% to 100%. That is, the hybrid vehicle 10 is configured as a kind of FFV (Flexible Fuel Vehicle).

  The communication state between the inside of the cylinder 201 and the intake pipe 207 is controlled by opening and closing the intake valve 211. The air-fuel mixture combusted inside the cylinder 201 becomes exhaust and is led to the exhaust pipe 215 via the exhaust port 214 when the exhaust valve 213 that opens and closes in conjunction with opening and closing of the intake valve 211 is opened.

  On the other hand, on the upstream side of the intake port 210 in the intake pipe 207, a throttle valve 208 for adjusting the intake air amount related to the intake air guided through a cleaner (not shown) is disposed. The throttle valve 208 is configured such that its drive state is controlled by a throttle valve motor 209 electrically connected to the ECU 100. The ECU 100 is basically configured to control the throttle valve motor 209 so that a throttle opening corresponding to the accelerator opening detected by the accelerator position sensor 800 is obtained. It is also possible to adjust the throttle opening without intervention of the driver's intention through the operation control. That is, the throttle valve 209 is configured as a kind of electronically controlled throttle valve.

  A three-way catalyst 216 is installed in the exhaust pipe 215. The three-way catalyst 216 is a catalyst capable of purifying CO (carbon monoxide), HC (hydrocarbon), and NOx (nitrogen oxide) discharged from the engine 200, respectively. The three-way catalyst 216 is provided with a catalyst bed temperature sensor 217 for detecting the catalyst bed temperature, which is the temperature of the three-way catalyst 216. The catalyst bed temperature sensor 217 is electrically connected to the ECU 100, and the detected catalyst bed temperature is grasped by the ECU 100 constantly or at a constant or indefinite period. The exhaust pipe 215 is provided with an air / fuel ratio sensor 218 configured to be able to detect the exhaust air / fuel ratio of the engine 200. In addition, a water jacket installed in a cylinder block that accommodates the cylinder 201 is provided with a water temperature sensor 219 for detecting a cooling water temperature related to cooling water (LLC) that is circulated and supplied to cool the engine 200. ing. The air-fuel ratio sensor 218 and the water temperature sensor 219 are electrically connected to the ECU 100, and the detected air-fuel ratio and cooling water temperature are grasped by the ECU 100 at a constant or indefinite period.

<Operation of Embodiment>
<Basic operation of hybrid vehicle 10>
In hybrid vehicle 10 of FIG. 1, power distribution among motor generator MG1, which mainly functions as a generator, motor generator MG2 which mainly functions as an electric motor, and engine 200, is controlled by ECU 100 and power split mechanism 300, and travels thereof. The state is controlled.

  For example, when hybrid vehicle 10 is started, motor generator MG1 is driven as an electric motor using electric power stored in battery 500. Engine 200 is cranked by the assist torque of motor generator MG1, and engine 200 is started.

  At the time of start, two types of operation states are selectively realized according to the state of charge of battery 500 based on the output signal of SOC sensor 600. For example, at the time of a normal start (that is, the SOC can be considered good or good), it is not necessary to charge the battery 500 by the motor generator MG1, so the engine 200 starts only for warm-up, and the hybrid The vehicle 10 starts by the power of the motor generator MG2 using the power stored in the battery 500 (that is, the power supplied to the power output from the MG2 is an example of “discharge power” according to the present invention). To do. On the other hand, when the state of charge is not good (that is, the SOC is lowered or can be regarded as lowered), motor generator MG1 functions as a generator by the power of engine 200, and battery 500 is charged. .

  For example, when the vehicle is traveling at a low speed or on a gentle slope, the efficiency of the engine 200 is relatively poor, so that the fuel injection through the injector 212 is stopped and the driving of the engine 200 with combustion is stopped. Thus, hybrid vehicle 10 travels only with the power from motor generator MG2. At this time, if the SOC is lowered, engine 200 starts to drive motor generator MG1, and battery 500 is charged by motor generator MG1.

  In the driving range where the fuel efficiency or combustion efficiency of the engine 200 is relatively good, the hybrid vehicle 10 travels mainly by the power of the engine 200. At this time, the power of the engine 200 is divided into two systems by the power split mechanism 300, one is transmitted to the wheel 13 via the axle 12, and the other is driven by the motor generator MG1 for power generation. Furthermore, motor generator MG2 is driven by the generated electric power, and the power of engine 200 is assisted by motor generator MG2. At this time, if the SOC is lowered, the output of engine 200 is increased, and a part of the electric power generated by motor generator MG1 is charged to battery 500.

  When deceleration is performed, the motor generator MG2 is rotated by the power transmitted from the wheel 13 via the axle 12, and the motor generator MG2 is operated as a generator. Thereby, a part of the kinetic energy of the wheel 13 is converted into electric energy, and the battery 500 is charged, so-called “regeneration” is performed.

<Basic control of engine 200>
Next, a basic control operation of the engine 200 will be described. ECU 100 repeatedly calculates an engine request output, which is an output required for engine 200, at a constant cycle. At this time, the ECU 100 stores in advance in the ROM based on the accelerator opening (that is, corresponding to the required load) detected by an unillustrated accelerator position sensor and the vehicle speed of the hybrid vehicle 10 detected by, for example, the vehicle speed sensor. An output shaft torque (torque to be output to the axle 12) corresponding to the accelerator opening and the vehicle speed at the present time is calculated from the stored map. Further, ECU 100 obtains the required power generation amount based on the output signal of SOC sensor 600, and corrects the output shaft torque with reference to the required power generation amount and the required amounts of various auxiliary devices (such as an air conditioner and power steering). Thus, the engine required output is calculated.

  It should be noted that the calculation method of the engine required output may be as executed in a known hybrid vehicle, and the details thereof may be variously changed as necessary. For example, the ECU 100 selectively obtains the required driving force, which is the driving force required for the driving wheel 13, from the driving force map stored in advance in the ROM based on the vehicle speed and the accelerator opening, and further this request. Based on the driving force, the vehicle speed, and the radius of the driving wheel (specifically, through these multiplication processes, etc.), a reference value of the required output is calculated, and this reference value is calculated based on the required power generation amount of the battery 500 and various supplementary values. The required output may be calculated by correcting based on the required output of the equipment.

<Details of start control>
The engine 200 is configured to be able to use an ethanol mixed fuel as described above. The ethanol mixed fuel is liable to lower the combustion performance of the engine 200 particularly at the time of start-up due to the latent heat of vaporization of ethanol. Further, in the engine 200, since the optimal air-fuel ratio of the fuel changes according to the ethanol concentration, the fuel property including the ethanol concentration needs to be accurately specified. Therefore, the hybrid vehicle 10 is configured such that the fuel property is appropriately detected in the process in which the ECU 100 performs start control to start the engine 200.

  Here, the details of the start control will be described with reference to FIG. FIG. 4 is a flowchart of the start control.

  In FIG. 4, the ECU 100 determines whether or not it is the start timing of the engine 200. If there is no operation for requesting engine start-up such as operation of the ignition key or pressing of the engine start button (step S101: NO), the ECU 100 repeats the processing related to step S101 until the start timing comes. , Control the process substantially to the standby state. Here, the presence / absence of the start input mainly by the operation of the driver is determined here, but the hybrid vehicle 10 includes motor generators MG1 and MG2 as driving force sources, and the engine 200 is appropriately set depending on the driving situation. Stop. Accordingly, apart from such an operation based on the driver's intention, whether or not the engine 200 needs to be started is appropriately determined on the ECU 100 side, and naturally the engine 200 may start automatically when viewed from the driver side. obtain. The start timing according to step S101 may include a timing at which this type of automatic input occurs.

  When it is the start timing of the engine 200 (step S101: YES), the ECU 100 determines whether or not a past learned value of the fuel property exists (step S102). The fuel property learning value will be described later. If there is no fuel property learning value (step S102: NO), the process proceeds to step S104. On the other hand, when the fuel property learning value exists (step S102: YES), the ECU 100 further determines whether or not it is the fuel property learning timing. Whether or not it is the fuel property learning timing is determined based on, for example, the presence or absence of a refueling operation after the previous learning, the elapsed time since the previous learning, and the like. For example, when a new refueling is performed or when a considerable amount of time has passed since the last learning, the fuel properties may have changed substantially due to physical or phase separation. Therefore, it is determined that the learning condition is satisfied.

  When it is the fuel property learning condition (step S103: YES), the ECU 100 acquires the driving condition of the hybrid vehicle 10 (step S104). In the process according to step S104, the outside air temperature and the cooling water temperature are acquired. The outside air temperature and the cooling water temperature acquired in the process according to step S104 are an example of “vehicle operating conditions” related to the operation of the first and second correction means according to the present invention.

  When the driving condition of the vehicle is acquired, ECU 100 determines the driving condition of engine 200 (step S105). Here, the driving conditions of the engine 200 according to the present embodiment indicate the fuel injection amount, the intake air amount, and the ignition timing. At this time, the driving condition of the engine 200 is set to a preset base condition. The base condition is a driving condition that is experimentally adapted to the base fuel property.

  Subsequently, ECU 100 determines a driving condition for motor generator MG1 (step S106). The driving condition of MG1 at the start is basically a fixed condition, but is appropriately corrected according to the SOC of battery 500 at that time detected by SOC sensor 600. For example, when the SOC is lowered, the power (input power) supplied to the MG 1 is suppressed to be lower than the basic condition, and when the SOC is sufficiently high, the input power is sometimes lower than the basic condition. Is also increased.

  When the driving conditions for MG1 are determined, ECU 100 drives MG1 via PCU 400 and starts motor assist (step S107). At this time, no explosion has occurred in engine 200, and engine 200 is cranked by motor generator MG1. That is, the assist torque output from motor generator MG1 at this stage refers to cranking torque.

  When cranking is started, ECU 100 determines whether engine 200 has reached the initial explosion state (step S108). If the first explosion has not yet been reached (step S108: NO), the cranking is continued, and the process is controlled to a standby state in step S108. On the other hand, when engine 200 reaches the first explosion (step S108: YES), ECU 100 acquires a cranking rotational speed NEkr that is an engine rotational speed at the time of cranking (step S109). The cranking rotational speed NEkr will be described later.

  Next, ECU 100 determines whether engine 200 has reached a complete explosion state (step S110). Here, in the present embodiment, the application of assist torque from motor generator MG1 is continued until engine 200 reaches the complete explosion state. Whether or not the complete explosion state has been reached is determined based on whether or not the engine rotational speed NE of the engine 200 has reached a preset target rotational speed (that is, the engine rotational speed for complete explosion determination). Done. For example, this target rotation speed is set to a value of approximately 1000 rpm. If the complete explosion is not reached (step S110: NO), the process is controlled to a standby state in step S110, and torque assist is continued.

  On the other hand, when the engine 200 has completed a complete explosion (step S110: YES), the ECU 100 acquires an assist time Tass, which is the time from when the engine 200 reaches the first explosion until the complete explosion (step S111). When the assist time Tass is acquired, the ECU 100 estimates the fuel property based on the acquired assist time Tass (step S112).

  Here, with reference to FIG. 5, it supplements about the operation | movement which concerns on estimation of a fuel property. FIG. 5 is a timing chart of various index values of the engine 200 in the starting control execution process.

  In FIG. 5, the characteristics relating to three types of index values are displayed in order from the top: engine torque Treg, which is output torque of engine 200, MG1 torque Trm, which is output torque of motor generator MG1, and engine speed NE. Further, the horizontal axis in these three types of characteristics is set to a common elapsed time. That is, FIG. 5 shows the time characteristics of these three types of index values.

  In FIG. 5, it is assumed that the engine 200 is started at time T0. In this case, application of assist torque (in this stage, cranking torque) from motor generator MG1 is started from time T0, and the locus of MG1 torque Trm rises as shown in the figure as PRF_BSE2 (see solid line). Here, as already described, the input power as the driving condition of the motor generator MG1 is managed so as to be constant at least at the time of starting, although it may be variable in some cases. Accordingly, when the engine rotational speed NE converges to a value that balances the friction of the engine 200 after a certain elapsed time after the start, the MG1 torque Trm becomes equal to the input power and the engine rotational speed NE (in this case, the rotational speed of the motor generator MG1). To a constant torque value Trm1 that is uniquely determined by:

  Here, the constant engine speed NE that balances this friction is the cranking speed NEkr described above. The cranking rotational speed NEkr decreases because the engine 200 consumes more MG1 torque Trm if the friction of the engine 200 is large, and the amount that the engine 200 consumes MG1 torque Trm decreases relatively if the friction is small. To rise. That is, the cranking rotational speed NEkr can be used as an index value that defines the friction of the engine 200, and is an example of the “degree of friction” according to the present invention. An example of “engine operating conditions”.

  On the other hand, when engine 200 reaches the first explosion in the process of continuing cranking, engine 200 spontaneously generates torque. In FIG. 5, the time T1 corresponds to the time when the engine 200 reaches the initial explosion state, and the engine torque Treg starts to increase at the time T1. On the other hand, when the engine 200 detonates at time T1, the engine speed NE starts to increase according to the increased engine torque Treg. Therefore, the value of the engine rotational speed NE changes relatively clearly before and after the first explosion.

  For this reason, the ECU 100 can easily and accurately determine whether or not the engine 200 has made an initial explosion (processing related to step S108 in FIG. 4) based on a change in the engine rotational speed NE. Further, MG1 torque Trm starts to decrease as engine rotational speed NE starts to increase at time T1, since there is no change in the input power of motor generator MG1.

  Here, each index value after the first explosion varies greatly according to the combustion characteristics of the fuel (that is, it correlates with the fuel properties). In FIG. 5, when a fuel having a relatively high ethanol concentration (ie, corresponding to a relatively good combustion characteristic) is used, and a fuel having a relatively low ethanol concentration (ie, relative combustibility). When the fuel is used), the characteristics of the engine torque Treg are PRF_BSE1 (see solid line) and the latter is PRF_ALC1 (see broken line). As for the characteristics of the MG1 torque Trm, the former is PRF_BSE2 (see solid line) and the latter is PRF_ALC2 (see broken line). Further, regarding the characteristics of the engine speed NE, the former is PRF_BSE3 (see solid line) and the latter is PRF_ALC3 (see broken line).

  As shown in the figure, when the combustibility of the fuel is poor, the combustion is not stable, so that the torque rise of the engine 200 is inevitably delayed. As a result, the increase in the engine speed NE is delayed. On the other hand, if the combustibility of the fuel is good, the torque of the engine 200 inevitably rises quickly and the engine speed NE rises faster. For example, assuming that the target rotational speed to be used for discrimination of complete explosion is NEtg (NEtg> NEkr), the engine 200 reaches a complete explosion state at time T2 and has a combustibility with characteristics corresponding to fuel with good combustibility. In characteristics corresponding to bad fuel, the engine 200 reaches a complete explosion state at time T3 after a time delay corresponding to that of time T2.

  On the other hand, since motor generator MG1 continues to apply assist torque until engine 200 completes explosion, MG1 torque Trm also changes in accordance with the fuel properties, similar to engine torque Treg and engine speed NE.

  As a result, the time transition of the MG1 torque Trm, which is the assist torque applied to the engine 200, changes according to the fuel properties, and the integrated value of the electric power input to the motor generator MG1 during the assist period is indicated by the shaded portion in the figure. Corresponding deviations occur. This deviation at least clearly corresponds to the fuel property, whether it is one-to-one, one-to-many, many-to-one or many-to-many, and can be used for estimation of the fuel property. It can be used as an example of “the degree of assistance in a part”.

  Further, not only the deviation but also the deviation of the engine torque Treg, the deviation of the engine speed NE, and the deviation of the length of the assist period are also examples of “the degree of assistance in at least a part of the assist period” according to the present invention. Can be used as Further, not only the deviation but also, for example, various index values themselves at a reference time may be used as the degree of assistance of this type.

  For example, it is assumed that the actual characteristic is a characteristic corresponding to the broken line in the figure when each characteristic when the fuel having the fuel property as the base is used is set to the characteristic represented by the solid line in the figure. In this case, for example, the value of the engine torque Treg (that is, Treg1 in the drawing) at the time T2 (that is, the time when the engine 200 should completely explode when the fuel having the base fuel property is used), or Treg1 ΔTrreg (that is, Trreg2-Trreg1 in the figure) that is a deviation from the value of the engine torque Treg (that is, Treg2 in the figure) when the fuel having the fuel characteristic serving as a base at time T2 is used is the actual fuel property. The index value is preferably expressed.

  Similarly, the value of MG1 torque Trm (Trm0 in the figure) and the similar deviation ΔTrm (that is, Trm0) can also be used as the correlation value of the fuel property. The same applies to the value of the engine rotational speed NE (shown NE1) or the deviation ΔNE of the engine rotational speed NE (that is, NETg-NE1 shown).

  Furthermore, if the fuel properties are different, the assist period may inevitably be lengthened or shortened. Therefore, the deviation between the length of the assist period and the actual length of the assist period when the fuel having the fuel property as the base is used (that is, the time corresponding to the time T3-T2), or simply the length of the assist period. It is also possible to accurately estimate the fuel properties based on the above.

  Returning to FIG. 4, in the process according to step S <b> 111, an assist time Tass, which is the length of the assist period, is acquired. The ECU 100 holds in advance a map for estimating fuel properties in a rewritable storage means such as a flash memory. In this map, the assist time Tass and the fuel property value FL representing the fuel property are associated with each other, and in the process according to step S112, one corresponding to the value of the assist time Tass obtained in the process according to step S111. The fuel property is estimated by selectively acquiring the fuel property value FL.

  Here, the friction of the engine 200 naturally exists even in a period after the initial explosion state is reached. Therefore, if the influence of the friction of the engine 200 cannot be separated, the fuel property may be estimated based on the behavior of various index values in the assist period as shown in FIG. 5 or the length Tass of the assist period. Errors can occur.

  On the other hand, in the present embodiment, the cranking rotational speed NEkr representing the degree of friction of the engine 200 is acquired in step S109, and the influence of the friction of the engine 200 is eliminated based on the cranking rotational speed NEkr. Is possible.

  That is, a plurality of maps for estimating the fuel properties described above are set in advance for each of a plurality of cranking rotational speeds NEkr. In the process related to step S112, one map corresponding to the cranking rotational speed NEkr acquired in the process related to step S109 is selected from the plurality of maps, and the assist as the degree of assist in the assist period described above is selected. By selectively acquiring the fuel property value corresponding to the time Tass, an accurate fuel property that excludes the influence of the friction of the engine 200 is estimated. At this time, the quantity of the cranking rotational speed NEkr as a parameter for selection of the map is set to an appropriate value without excess or deficiency, and there is no map corresponding to the corresponding cranking rotational speed NEkr. The map corresponding to the nearest cranking rotational speed NEkr is used. Alternatively, the fuel property may be estimated by interpolating values obtained selectively from a map corresponding to two types of cranking rotational speeds sandwiching a desired cranking rotational speed NEkr.

  Further supplementally, the friction of the engine 200 is affected by the cranking torque (that is, defined by the input power) by the MG1, the lubricating oil temperature, and the like. More specifically, when the cranking torque changes, the frictional supply state of the lubricating oil to each sliding portion in the engine 200 changes, so that the friction changes. The lubricating oil has a viscous resistance according to its temperature. Since it changes, the circulation supply state can change.

  Therefore, when specifying the friction of the engine 200, it is desirable to perform a correction process reflecting various index values that can define the friction. Therefore, the ECU 100 estimates the fuel property value FL selectively acquired from the map when estimating the fuel property according to step S112, using the outside air temperature or the cooling water temperature and the cranking torque obtained by the processing according to step S104 and step S106. Correct according to the value of. In the present embodiment, the fuel property value FL is directly corrected as described above, but the operation related to the correction is substantially equivalent to correcting the friction of the engine 200 indirectly. This is nothing but the operation relating to the “first correction means”. Note that the friction of the engine 200 correlates with, for example, a compression reaction force. Therefore, when the valve timing, the lift amount, etc. can be changed via VVT or the like, the friction or the fuel property may be similarly corrected according to the change amount or the control amount.

  On the other hand, the outside air temperature, the cooling water temperature, the intake air amount, the fuel injection amount, the ignition timing, and the like can affect the combustion performance of the engine 200. Accordingly, the change in the change can appear as a change in the characteristics of the various index values described above during the assist period. Therefore, in the process according to step S112, the ECU 100 further sets the fuel property value according to the outside air temperature or the cooling water temperature and the injection amount, the intake air amount, and the ignition timing acquired in the processes according to step S104 and step S105. to correct. At this time, the obtained fuel property value may be used for correction calculation as various numerical calculations, for example, but if the map to be used for estimation of the fuel property is further subdivided according to these in advance, An appropriate map may be appropriately selected each time, and one fuel property value corresponding to the assist period Tass may be acquired from the selected map. In any case, such an operation is an example of the operation related to the “second correction unit” according to the present invention.

  When the fuel property is estimated, a fuel property learning process is executed (step S113). Here, the fuel property learning process is a process of updating the fuel property value FL obtained in step S112 by replacing the previous learned value with a value stored in a storage unit such as a flash memory. is there. However, in the processing according to step S113, the necessity for updating may be taken into consideration as appropriate. For example, when the fuel property value FL is equal to the previous value or equivalent to the extent that can be regarded as equal, the updating is appropriately performed. It may be skipped. When the fuel property learning is completed, the process returns to step S101, and a series of processes is repeated. Note that, once the process according to step S113 is executed, it is determined in the process according to step S102 that there is a fuel property learning value (that is, the stored fuel property value FL).

  On the other hand, when it is determined in the process according to step S103 that the fuel property learning process is not performed (step S103: NO), the ECU 100 determines the fuel property learning value FL (that is, the fuel stored in the process according to step S113). The property value FL) is acquired (step S114). Next, an engine drive condition corresponding to the acquired fuel property learning value FL is set (step S115), and further a drive condition for MG1 is set (step S116). Through these processes, the motor assist is started (step S117). When the complete explosion is not reached (step S117: NO), the motor assist is continued and when the complete explosion is reached (step S118). : YES), the process is returned to step S101. That is, the fuel property learning in the present embodiment is performed at an appropriate timing at which the fuel property is to be learned, and in other situations, the optimal combustion based on the accurate fuel property value FL that has already been acquired. Control is executed.

  In this embodiment, an index value that can regulate the temperature of the lubricating oil such as the outside air temperature or the cooling water temperature is referred to, and the friction is directly or indirectly corrected to reflect the change in the viscous resistance of the lubricating oil. However, depending on the performance, characteristics, specifications, or degree of deterioration of the lubricating oil, there may be a case where no significant change in the viscous resistance occurs except in an extremely low temperature region of several tens of degrees below freezing. In view of such circumstances, the correction by the outside air temperature or the cooling water temperature or the like may be performed only at the start of this kind of cryogenic temperature. In addition, when there is no factor that remarkably controls friction other than this type of viscous resistance, for example, when learning the fuel properties, the processing related to step S109 is skipped and the processing related to fuel property estimation related to step S112 is performed. May be simplified.

  In this embodiment, the assist period length Tass is used as an example of the degree of assist according to the present invention. However, as long as it does not affect the estimation accuracy of the fuel property in practice, the assist period It is not necessary to refer to all (that is, the period from the first explosion to the complete explosion). That is, before the engine 200 reaches the complete explosion state, the fuel property may be estimated based on the value of the assist torque applied from the motor generator MG1, for example. The same applies to the cranking rotational speed NEkr, and the cranking rotational speed NEkr may be specified without waiting for the end of the cranking period.

  In any case, according to the start control according to the present embodiment, the degree of torque assist in at least a part of the assist period from the first explosion to the complete explosion, the value of the engine speed NE in at least a part of the cranking period, etc. It is possible to accurately estimate the fuel property in the ethanol mixed fuel based on the friction state of the engine 200 estimated from the above.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the fuel property estimation device with such a change. Is also included in the technical scope of the present invention.

1 is a schematic configuration diagram conceptually illustrating a configuration of a hybrid vehicle according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a relationship between a power split mechanism and its peripheral part in the hybrid vehicle of FIG. 1. It is a schematic diagram of the engine in the hybrid vehicle of FIG. 2 is a flowchart of start control executed by an ECU in the hybrid vehicle of FIG. 5 is a timing chart of various index values of the engine in the execution process of the start control in FIG. 4.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Hybrid vehicle, 100 ... ECU, 200 ... Engine, 201 ... Cylinder, 203 ... Piston, 205 ... Crankshaft, 300 ... Power split mechanism, 301 ... Ring gear, 303 ... Sun gear, 306 ... Planetary carrier, 500 ... Battery, 600 ... SOC sensor.

Claims (9)

An apparatus for estimating the fuel property of the fuel in a vehicle provided with an internal combustion engine capable of using fuel mixed with alcohol and assist means capable of assisting torque including cranking with respect to the internal combustion engine,
Control means for controlling the assist means and the internal combustion engine so that the internal combustion engine reaches a predetermined complete explosion state with the assist when starting the internal combustion engine;
First specifying means for specifying the degree of friction of the internal combustion engine;
Second specifying means for specifying the degree of assist in at least a part of an assist period from when the internal combustion engine reaches a predetermined initial explosion state until reaching the complete explosion state;
An estimation means for estimating the fuel property based on the specified degree of friction and the degree of assistance. 2. The fuel property according to claim 1, wherein when the internal combustion engine is cold-started, the estimation unit estimates the fuel property based on the identified degree of friction and degree of assist. Estimating device. The first specifying means specifies, as the degree of friction, an operating condition of the internal combustion engine in at least a part of a cranking period until the internal combustion engine reaches the initial explosion state. Item 3. The fuel property estimation apparatus according to Item 1 or 2. The fuel property estimation device according to claim 3, wherein the operating condition of the internal combustion engine in at least a part of the cranking period is an engine speed of the internal combustion engine. Further comprising first correcting means for correcting the degree of friction according to the driving conditions of the vehicle;
The fuel property estimation apparatus according to claim 3, wherein the estimation unit estimates the fuel property based on the corrected degree of friction. The first specifying means includes at least one of index values defining the length of the assist period, the engine speed of the internal combustion engine, and the output state of the assist means as the degree of assistance in at least a part of the assist period. The fuel property estimation device according to claim 1, wherein one is specified. The fuel property estimation apparatus according to any one of claims 1 to 6, further comprising a second correction unit that corrects the fuel property according to an operation condition of the vehicle. A learning means for learning the estimated fuel property;
The fuel according to any one of claims 1 to 7, wherein the control means controls the internal combustion engine and the assist means based on the learned fuel property at the time of starting after the next time. Property estimation device. 9. The hybrid vehicle having at least one electric motor that functions as a driving force source of the vehicle together with the internal combustion engine, and at least a part of which functions as the assist means. The fuel property estimation device according to any one of the above.

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