Engine control device

Abstract

To provide an engine control device capable of efficiently driving an engine while suppressing increase in a fuel oil consumption.SOLUTION: A control device changes an engine operation line to an operation line corresponding to an alcohol concentration under the condition that engine warm-up is completed (step S130). Thereby, at the time when the engine warm-up is completed (step S130:YES), the control device changes an operation point set corresponding to a required output so as to be on a higher torque side and a lower rotation frequency side when the alcohol concentration of the mixed fuel is higher than the case when the alcohol concentration of the mixed fuel is lower (step S150). At the time when the engine warm-up is not completed (step S130:NO), the control device does not execute the change corresponding to the alcohol concentration of the mixed fuel, with respect to the operation point set corresponding to the required output (step S140).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an engine control device. [Background technology]

[0002] Engines that can use alcohol-blended fuel, which is a mixture of alcohol and gasoline fuels in any ratio, are known. Patent Document 1 discloses a control device for controlling an engine that can use alcohol-blended fuel. Alcohol fuel has a higher octane rating than gasoline fuel. A higher octane rating reduces the likelihood of knocking, allowing for ignition timing advancement to generate higher torque. The control device disclosed in Patent Document 1 changes the engine's operating point according to the fuel's octane rating to maximize thermal efficiency or approach a state where thermal efficiency is maximized. The engine's operating point is determined by the engine torque and engine speed that achieve a required output. The control device controls the engine to achieve the engine torque and engine speed that define the operating point set according to the required output. Specifically, the control device disclosed in Patent Document 1 shifts the engine's operating point, set according to the required output, toward a higher torque and lower engine speed as the octane rating of the fuel increases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-162649 Summary of the Invention [Problem to be solved by the invention]

[0004] Alcohol fuel vaporizes less easily than gasoline fuel when the fuel temperature is low. Therefore, when the fuel temperature is low, the higher the alcohol concentration in the fuel, the more likely it is that poor combustion will occur. When poor combustion occurs, the engine will not be able to operate efficiently. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. An engine control device for solving the above problem is an engine control device for use in a vehicle equipped with an engine that can use a blended fuel in which alcohol fuel and gasoline fuel are blended in any ratio. This control device controls the engine to achieve engine torque and engine speed that define an operating point that is set according to a required output. The control device changes the operating point that is set according to the required output to a higher torque and lower engine speed when the alcohol concentration of the blended fuel is high compared to when the alcohol concentration of the blended fuel is low, on the condition that warm-up of the engine is complete. Thus, when the engine warm-up is not complete, the control device does not change the operating point that is set according to the required output in accordance with the alcohol concentration of the blended fuel. [Effects of the Invention]

[0006] This engine control device can operate the engine efficiently by suppressing an unnecessary increase in the fuel injection amount. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a drive system of a hybrid vehicle to which an embodiment of an engine control device is applied. [Figure 2] FIG. 2 is a diagram showing the relationship between engine torque and thermal efficiency in the control device of the embodiment. [Figure 3]FIG. 3 is a diagram showing a setting mode of the operating line in the control device of the embodiment. [Figure 4] FIG. 4 is a flowchart of engine control in the control device of the embodiment. [Figure 5] FIG. 5 is a diagram showing the relationship between the operating line and the engine torque limit in the control device of the embodiment. [Figure 6] FIG. 6 is a flowchart of engine control in the control device of the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of an engine control device will be described below with reference to FIGS. First, the configuration of a drive system of a hybrid vehicle that is the object of control by an engine control device 10 of this embodiment will be described with reference to Figure 1. This control device 10 also serves as a control device for the hybrid system.

[0009] 1, a hybrid vehicle to which the control device 10 is applied includes an engine 11, a fuel tank 12, a first motor generator MG1, a second motor generator MG2, a power distribution mechanism 13, an inverter 26, and a battery 27. The engine 11 is an engine that can use a mixed fuel in which alcohol fuel and gasoline fuel are mixed in any ratio.

[0010] The power distribution mechanism 13 is composed of a sun gear 14, a pinion gear 15, a planetary carrier 16, and a ring gear 17. The sun gear 14 rotates around the center of the ring gear 17. The pinion gear 15 is interposed between the sun gear 14 and the ring gear 17 and revolves around the sun gear 14. The planetary carrier 16 rotates due to the revolution of the pinion gear 15. An output shaft of the engine 11 is connected to the planetary carrier 16. A first motor generator MG1 is connected to the sun gear 14. A counter drive gear 18 is integrally provided with the ring gear 17. A counter driven gear 19 is meshed with the counter drive gear 18. The second motor generator MG2 is connected to a reduction gear 20 that is meshed with the counter driven gear 19. A final drive gear 21 is connected to the counter driven gear 19 so as to be rotatable together with the counter driven gear 19, and a final driven gear 22 is meshed with the final drive gear 21. A drive shaft 25 of drive wheels 24 is connected to the final driven gear 22 via a differential mechanism 23.

[0011] The first motor generator MG1 and the second motor generator MG2 exchange electric power with a battery 27 via an inverter 26. The inverter 26 is a power conversion circuit that converts the terminal voltage of the battery 27, which is a DC voltage source, into AC current and outputs it.

[0012] The engine 11 is provided with an ignition device 29 and an injector 30. One ignition device 29 and one injector 30 are provided for each cylinder of the engine 11. The engine 11 is also provided with a throttle valve.

[0013] Fuel in a fuel tank 12 is supplied to the engine 11 through a fuel supply line 35. The fuel tank 12 is provided with an alcohol concentration sensor 36 that detects the alcohol concentration of the mixed fuel.

[0014] The control device 10 controls the engine 11, the first motor generator MG1, and the second motor generator MG2. That is, the control device 10 controls the power train of the vehicle. The control device 10 is connected to an air flow meter 31, a crank angle sensor 33, a water temperature sensor , an alcohol concentration sensor , an accelerator opening sensor 37, and a vehicle speed sensor .

[0015] The air flow meter 31 is a sensor that detects the amount of intake air in the intake passage of the engine 11. The crank angle sensor 33 is a sensor that detects the crank angle, which is the rotation angle of the crankshaft of the engine 11. The water temperature sensor 34 is a sensor that detects the engine coolant temperature, which is the temperature of the coolant for the engine 11. The accelerator opening sensor 37 is a sensor that detects the accelerator opening. The vehicle speed sensor 38 is a sensor that detects the speed of the vehicle.

[0016] The control device 10 acquires the engine speed Ne, which is the rotational speed of the crankshaft of the engine 11, from the crank angle sensor 33. The control device 10 calculates the required output of the engine 11 based on the accelerator opening acquired from the accelerator opening sensor 37 and the vehicle speed acquired from the vehicle speed sensor 38. The control device 10 operates the throttle valve, the ignition device 29, and the injector 30 to control the torque, which is the control variable of the engine 11. To control the engine 11, the control device 10 refers to the intake air amount detected by the air flow meter 31, the engine coolant temperature detected by the water temperature sensor 34, and the alcohol concentration of the mixed fuel detected by the alcohol concentration sensor 36. The control device 10 operates the inverter 26 to control the first motor generator MG1 and the second motor generator MG2.

[0017] Here, referring to Figure 2, we will explain how the relationship between engine torque Te and thermal efficiency η changes depending on the alcohol concentration of the blended fuel when the engine speed Ne is constant. The subscripts "E0," "E50," and "E100" in Figures 2 and 3 indicate the alcohol concentration of the blended fuel. In the following, the subscripts will be written with "_" before them.

[0018] 2, thermal efficiency curves L_E0, L_E50, and L_E100 are the thermal efficiency curve L of the engine 11 when the alcohol concentrations of the blended fuel are 0%, 50%, and 100%, respectively. For example, on the thermal efficiency curve L_E0, the thermal efficiency η when the engine 11 is operated at an engine torque Te_E0 is η_E0.

[0019] When the engine speed Ne is constant, the higher the torque, the greater the rate at which the thermal energy generated when fuel is burned is converted into work, thereby improving the thermal efficiency η. However, when the engine 11 is operated according to the thermal efficiency curve L_E0, i.e., when the engine 11 is operated using only gasoline fuel, knocking occurs and the thermal efficiency η decreases when the engine torque Te is greater than the engine torque Te_E0. On the other hand, when the engine 11 is operated according to the thermal efficiency curve L_E100, i.e., when the alcohol concentration of the blended fuel is 100%, knocking is less likely to occur than when only gasoline is used as fuel because the fuel has a high octane rating. Therefore, the engine 11 can be operated at a higher torque. As shown in Figure 2, the thermal efficiency curve L_E100 exhibits the maximum thermal efficiency η_E100 when the engine torque Te_E100 is higher than the engine torque Te_E0. The thermal efficiency η_E100, which is the maximum value of the thermal efficiency η on the thermal efficiency curve L_E100, is higher than the thermal efficiency η_E0, which is the maximum value of the thermal efficiency η on the thermal efficiency curve L_E0. In other words, the higher the alcohol concentration of the blended fuel, the more the engine 11 can be operated with high torque without causing knocking, and therefore the engine 11 can be operated with high thermal efficiency η.

[0020] Here, with reference to Fig. 3, control of the engine 11 according to an operating line Q that connects multiple operating points set in accordance with the required output of the engine 11 on a coordinate plane whose axes are the engine torque Te and the engine speed Ne will be described. The operating points are defined by the engine torque Te and the engine speed Ne. For example, the operating points indicated by black circles in Fig. 3 are operating points defined by the engine torque Te_E0 and the engine speed Ne_E0. The operating points indicated by open triangles in Fig. 3 are operating points defined by the engine torque Te_E100 and the engine speed Ne_E100.

[0021] As shown in FIG. 3, operating lines Q_E0, Q_E50, and Q_E100 are operating lines Q that connect operating points at which the engine 11 exhibits maximum thermal efficiency η when the alcohol concentration of the blended fuel is 0%, 50%, and 100%, respectively. Furthermore, an equal power output line Pn is a line that connects operating points at which the engine output is equal. The equal power output line Pn exists depending on the magnitude of the required output. In FIG. 3, the equal power output line Pn corresponding to a higher required output is located on the higher torque and higher rotation side.

[0022] The control device 10 determines an operating point for operating the engine 11 using the selected operating line Q and the equal power line Pn corresponding to the required output. Then, the control device 10 controls the engine 11 to achieve the engine torque Te and engine speed Ne that define the operating point.

[0023] For example, when realizing the required output corresponding to the equal power output line Pn shown in Fig. 3, if the control device 10 selects the operating line Q_E0, the control device 10 operates the engine 11 at the engine torque Te_E0 and engine speed Ne_E0. In other words, the control device 10 operates the engine 11 at the operating point indicated by the black circle, which is the intersection of the equal power output line Pn and the operating line Q_E0.

[0024] On the other hand, when the control device 10 selects the operating line Q_E100, the control device 10 operates the engine 11 at an engine torque Te_E100 and an engine speed Ne_E100, thereby realizing an output corresponding to the equal power output line Pn. In other words, the control device 10 operates the engine 11 at the operating point indicated by the open triangle, which is the intersection of the equal power output line Pn and the operating line Q_E100.

[0025] 2, since the thermal efficiency η improves as the engine torque Te increases, the engine 11 can be operated at a higher thermal efficiency η when the required output of the engine 11 is the same as the alcohol concentration of the blended fuel. Therefore, by changing the operating line Q of the engine 11 used to calculate the operating point corresponding to the required output in accordance with the alcohol concentration of the blended fuel, the control device 10 can operate the engine 11 efficiently.

[0026] The operating line Q is set not only for the cases where the alcohol concentration of the blended fuel is 0%, 50%, and 100%, but also for a plurality of operating lines Q corresponding to the alcohol concentration of the blended fuel. In this case, the operating line Q corresponding to the blended fuel with a higher alcohol concentration is located closer to the high torque side on the coordinate plane shown in FIG.

[0027] As described above, when the control device 10 selects the operating line Q_E100, the control device 10 operates the engine 11 at a higher torque and a lower rotation speed than when the control device 10 selects the operating line Q_E0. When operating the engine 11 at a higher torque and a lower rotation speed, the control device 10 needs to increase the amount of fuel injected by the injector 30 per injection.

[0028] Incidentally, alcohol fuel is less likely to vaporize than gasoline fuel when the fuel temperature is low. Also, when the engine 11 has not yet warmed up, the temperature of the fuel injected from the injector 30 is low. Therefore, if the fuel injection amount is increased when the engine 11 has not yet warmed up, i.e., when the fuel is less likely to vaporize, poor combustion will occur, resulting in unnecessary fuel consumption.

[0029] Therefore, the control device 10 changes the operating curve Q according to the alcohol concentration of the blended fuel, on the condition that the warm-up of the engine 11 has been completed. 4 shows the flow of a series of processes executed by the control device 10. This series of processes is repeatedly executed by the control device 10 while the engine 11 is running.

[0030] 4, when this series of processes starts, the control device 10 first acquires the alcohol concentration of the blended fuel in the process of step S100. That is, the control device 10 acquires the alcohol concentration of the blended fuel from the detection signal of the alcohol concentration sensor 36 installed in the fuel tank 12. Next, in the process of step S110, the control device 10 acquires the engine coolant temperature from the detection signal of the water temperature sensor 34.

[0031] Next, in the process of step S120, the control device 10 determines whether the alcohol concentration of the blended fuel is equal to or greater than a set concentration. For example, the set concentration is 30%. The set concentration is set to a magnitude such that it can be determined that the blended fuel contains alcohol fuel based on whether the alcohol concentration is equal to or greater than the set concentration. If the alcohol concentration of the blended fuel is equal to or greater than the set concentration (S120: YES), the process proceeds to step S130.

[0032] In the process of step S130, the control device 10 determines whether the engine coolant temperature is equal to or higher than a set temperature. This process is a process for determining whether the warm-up of the engine 11 has been completed. For example, the set temperature is 70°C. Furthermore, if the engine coolant temperature is equal to or higher than 70°C, the mixed fuel is easily vaporized. In the process of step S130, if the control device 10 determines that the engine coolant temperature is equal to or higher than the set temperature (step S130: YES), the control device 10 determines that the warm-up of the engine 11 has been completed. Then, the process proceeds to step S150.

[0033] In the process of step S150, the control device 10 changes the operating line Q of the engine 11 in accordance with the alcohol concentration of the blended fuel, as shown in Fig. 3. Specifically, the higher the alcohol concentration of the blended fuel, the higher the operating line Q that the control device 10 selects.

[0034] Next, in the process of step S160, the control device 10 determines whether or not the torque distributed from the engine 11 to the first motor generator MG1 is less than the rated torque of the first motor generator MG1.

[0035] As shown in FIG. 1, in the case of a hybrid vehicle, in order to transmit engine torque Te to drive wheels 24, control device 10 needs to control first motor generator MG1 via inverter 26 to generate torque that suppresses rotation of sun gear 14. In this way, control device 10 prevents sun gear 14 from spinning freely, which would result in consumption of torque generated by engine 11. If the magnitude of the torque required to suppress rotation of sun gear 14 exceeds the rated torque of first motor generator MG1, rotation of sun gear 14 cannot be suppressed sufficiently, and the torque generated by engine 11 is not sufficiently transmitted to drive wheels 24. Furthermore, if the torque applied to first motor generator MG1 exceeds the rated torque of first motor generator MG1, an excessive load is placed on first motor generator MG1.

[0036] As shown in Fig. 3, the higher the alcohol concentration of the blended fuel, the more the operating line Q is shifted to the high torque side, allowing the engine 11 to be operated at a high thermal efficiency η. On the other hand, as the engine torque Te increases, the torque of the first motor generator MG1 required to suppress the rotation of the sun gear 14 also increases.

[0037] As shown in Fig. 5, the torque of the engine 11 when the torque of the first motor generator MG1 becomes the rated torque is defined as the maximum engine torque Te_MAX. When the torque of the engine 11 exceeds the maximum engine torque Te_MAX, the control device 10 controls the engine 11 within a range that does not exceed the maximum engine torque Te_MAX. As described above, when the engine torque Te exceeds the maximum engine torque Te_MAX, the first motor generator MG1 cannot fully suppress the rotation of the sun gear 14, and the torque generated by the engine 11 is not sufficiently transmitted to the drive wheels 24.

[0038] 4 again, if the engine torque Te distributed to the first motor generator MG1 exceeds the rated torque of the first motor generator MG1 (step S160: NO), in the process of step S170, the control device 10 limits the engine torque Te so that it does not exceed the maximum engine torque Te_MAX. Then, in the process of step S180, the control device 10 determines an operating point using the selected operating line Q while limiting the engine torque Te, and controls the engine 11. Specifically, as shown in FIG. 5, the control device 10 controls the engine 11 using the operating line Q while limiting the engine torque Te so that it does not exceed the maximum engine torque Te_MAX.

[0039] If the engine torque Te distributed to the first motor generator MG1 is less than the rated torque of the first motor generator MG1 (step S160: YES), the engine torque Te is not limited. That is, the control device 10 determines an operating point using the selected operating line Q and controls the engine 11 (step S180).

[0040] In the process of step S120, if the control device 10 determines that the alcohol concentration of the blended fuel is lower than the set concentration (step S120: NO), the control device 10 selects the operating line Q_E0. Then, the control device 10 determines an operating point using the selected operating line Q and controls the engine 11 (step S180).

[0041] In the process of step S130, even if the control device 10 determines that the engine coolant temperature is lower than the set temperature (step S130: NO), the control device 10 selects the operating line Q_E0. Then, the control device 10 determines an operating point using the selected operating line Q and controls the engine 11 (step S180).

[0042] After executing the process of step S180, the control device 10 temporarily ends this series of processes. <Operation of this embodiment> In the above series of processes, when the temperature of the engine 11 is low (step S130: NO), the control device 10 does not change the operating point to the high torque side (step S140). In other words, when efficient operation cannot be achieved even if the operating point is changed to the high torque side, the control device 10 does not change the operating point to the high torque side.

[0043] <Effects of this embodiment> (1) The control device 10 can operate the engine 11 efficiently by suppressing an unnecessary increase in the fuel injection amount.

[0044] (2) On a coordinate plane with the engine torque Te and the engine speed Ne as axes, a plurality of operating lines Q, each connecting a plurality of operating points set according to the required output of the engine 11, are set in correspondence with the alcohol concentration of the blended fuel. On the coordinate plane, the operating lines Q corresponding to blended fuels with higher alcohol concentrations are located closer to the high torque side. The control device 10 changes the operating point set according to the required output by selecting an operating line Q to be used when calculating the operating point according to the required output from among the plurality of operating lines Q in accordance with the alcohol concentration of the blended fuel. The control device 10 can change the operating point by selecting an operating line Q according to the alcohol concentration.

[0045] (3) A hybrid vehicle to which the control device 10 is applied includes a power distribution mechanism 13 having a ring gear 17 interlocked with drive wheels 24, a sun gear 14, pinion gears 15, and a planetary carrier 16. The hybrid vehicle also includes an engine 11 whose output shaft is connected to the planetary carrier 16, a first motor generator MG1 interlocked with the sun gear 14, a second motor generator MG2 interlocked with the ring gear 17, and a battery 27. The control device 10 limits engine torque Te so that the torque distributed from the engine 11 to the first motor generator MG1 through the power distribution mechanism 13 does not exceed the rated torque of the first motor generator MG1. The control device 10 prevents an excessive load from being applied to the first motor generator MG1 and can efficiently transmit engine torque Te to the drive wheels 24.

[0046] (4) When the alcohol concentration of the blended fuel is high, the control device 10 changes the operating point, which is set according to the required output, so that it is on the higher torque and lower rotation speed side compared to when the alcohol concentration of the blended fuel is low. The control device 10 performs this change on the condition that the alcohol concentration of the blended fuel is equal to or higher than a predetermined set concentration and the engine 11 has been warmed up. The alcohol concentration of the blended fuel grasped by the control device 10 has a certain degree of error. Therefore, changing the operating point according to the alcohol concentration of the blended fuel may not be effective unless it is performed when the alcohol concentration of the blended fuel is relatively high. In this control device 10, the condition for performing the operating point change also includes the alcohol concentration of the blended fuel being equal to or higher than the set concentration. Therefore, the operating point change can be performed when the conditions for the change to be effective are met.

[0047] (5) The control device 10 acquires the engine coolant temperature detected by the water temperature sensor 34, and when the acquired engine coolant temperature is equal to or higher than a predetermined set temperature, determines that the warm-up of the engine 11 is complete. The control device 10 can determine that the warm-up of the engine 11 is complete based on the engine coolant temperature acquired using the water temperature sensor 34.

[0048] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0049] If the torque of the first motor / generator MG1 does not exceed the rated torque when the engine 11 is operated at the maximum engine torque Te_MAX, the control device 10 does not need to limit the engine torque Te. In this case, as shown in Fig. 6, the control device 10 may control the engine 11 by executing a series of processes that omits steps S160 and S170.

[0050] The control device 10 does not have to also function as a control device for the hybrid system. In this case, a control device for the hybrid system is installed in the vehicle separately from the control device 10. The control device 10 may be applied to a vehicle equipped with only the engine 11 as a driving force source. In this case, as shown in Fig. 6, the control device 10 may control the engine 11 by executing a series of processes that omits steps S160 and S170.

[0051] Instead of selecting the operating line Q, the control device 10 may control the engine 11 by changing the operating point to an appropriate engine torque Te and engine speed Ne according to the alcohol concentration of the blended fuel and the required output.

[0052] In this embodiment, the control device 10 continuously shifts the operating line Q toward the higher torque side as the alcohol concentration of the blended fuel increases. Alternatively, the control device 10 may control the engine 11 to change the operating point to the high-torque and low-speed side when the alcohol concentration of the blended fuel exceeds a threshold. For example, the control device 10 shifts the operating line Q to the operating line Q_E0 when the alcohol concentration of the blended fuel is between 0% and less than 50%, to the operating line Q_E50 when the alcohol concentration of the blended fuel is between 50% and less than 100%, and to the operating line Q_E100 when the alcohol concentration is 100%. The control device 10 controls the engine 11 to achieve the engine torque Te and engine speed Ne that define the operating point set according to the required output on the selected operating line Q. In other words, when the alcohol concentration of the blended fuel is high, the control device 10 shifts the operating point to the higher torque and lower speed side compared to when the alcohol concentration of the blended fuel is low.

[0053] The control device 10 may omit the process of step S120. In this case, if the blended fuel contains alcohol, the control device 10 changes the operating point so that when the alcohol concentration of the blended fuel is high, the operating point is on the higher torque side and lower rotation speed side than when the alcohol concentration of the blended fuel is low.

[0054] In this embodiment, the control device 10 determines whether the alcohol concentration of the blended fuel is higher than a set concentration based on the alcohol concentration acquired by the alcohol concentration sensor 36 installed in the fuel tank 12. Alternatively, the control device 10 may estimate the alcohol concentration value of the blended fuel from the learned value of the exhaust air-fuel ratio. Compared to gasoline fuel, alcohol fuel has a lower stoichiometric air-fuel ratio. Therefore, as the alcohol concentration of the blended fuel increases, the stoichiometric air-fuel ratio of the blended fuel decreases. In other words, for a given fuel injection amount, as the alcohol concentration of the blended fuel increases, the exhaust air-fuel ratio decreases. Here, the exhaust air-fuel ratio when the alcohol concentration is 0% is defined as the reference air-fuel ratio. The control device 10 can estimate the alcohol concentration of the blended fuel from the difference between the exhaust air-fuel ratio acquired by the air-fuel ratio sensor and the reference air-fuel ratio and the pre-stored stoichiometric air-fuel ratios for each alcohol concentration of the blended fuel.

[0055] Instead of determining the alcohol concentration of the blended fuel based on the alcohol concentration acquired by the alcohol concentration sensor 36 installed in the fuel tank 12, the control device 10 may estimate the alcohol concentration value of the blended fuel from a feedback value of the fuel injection amount. As described above, as the alcohol concentration of the blended fuel increases, the stoichiometric air-fuel ratio of the blended fuel decreases. In other words, the control device 10 needs to feedback control the fuel injection amount based on the air-fuel ratio acquired by the air-fuel ratio sensor. The control device 10 can estimate the alcohol concentration of the blended fuel from the fuel injection amount obtained as a result of the feedback control and the fuel injection amount for each alcohol concentration of the blended fuel stored in advance.

[0056] The control device 10 may determine whether or not the warm-up has been completed based on the engine oil temperature acquired by the engine oil temperature sensor. When determining whether the warm-up of the engine 11 is complete, the control device 10 may estimate the warm-up state of the engine 11 from the past operating history of the engine 11. For example, the control device 10 may determine that the warm-up is complete when the engine 11 starts and continues to operate at or above a certain engine speed Ne for a certain period of time or more.

[0057] When determining whether the warm-up of the engine 11 is complete, the control device 10 may determine that the warm-up is complete when the cumulative intake air amount since the start of operation is equal to or greater than a predetermined value. The control device 10 may obtain information on the cumulative intake air amount from the air flow meter 31. [Explanation of symbols]

[0058] 10...control device, 11...engine, 12...fuel tank, 13...power distribution mechanism, 14...sun gear, 15...pinion gear, 16...planetary carrier, 17...ring gear, 18...counter drive gear, 19...counter driven gear, 20...reduction gear, 21...final drive gear, 22...final driven gear, 23...differential mechanism, 24...drive wheel, 25...drive shaft, 26...inverter, 27...battery, 29...ignition device, 30...injector, 31...air flow meter, 33...crank angle sensor, 34...water temperature sensor, 35...fuel supply path, 36...alcohol concentration sensor, 37...accelerator opening sensor, 38...vehicle speed sensor, MG1...first motor generator, MG2...second motor generator

Claims

1. A power distribution mechanism having a ring gear that is linked with a drive wheel, a sun gear that rotates at the center of said ring gear, a pinion gear that is interposed between said sun gear and said ring gear and revolves around said sun gear, and a planetary carrier that rotates due to the revolution of said pinion gear; an engine capable of using a mixed fuel of alcohol fuel and gasoline fuel, the engine having an output shaft connected to the planetary carrier; a first motor generator interlocked with the sun gear; a second motor generator interlocked with the ring gear; a battery that exchanges electric power between the first motor generator and the second motor generator, An engine control device that controls an engine so as to realize an engine torque and an engine speed that define an operating point that is set according to a required output, a plurality of operating lines connecting a plurality of operating points set in accordance with an output required for the engine on a coordinate plane having the engine torque and the engine rotation speed as axes, the operating lines being set in correspondence with the alcohol concentration of the blended fuel; the operating lines are positioned on the coordinate plane such that an operating line corresponding to the mixed fuel having a higher alcohol concentration is positioned closer to a higher torque side; On the condition that warming up of the engine has been completed, an operating line used in calculating the operating point corresponding to the required output is selected from the plurality of operating lines in accordance with the alcohol concentration of the blended fuel, thereby changing the operating point set in accordance with the required output so that when the alcohol concentration of the blended fuel is high, the operating point is positioned on the higher torque side and lower rotation speed side than when the alcohol concentration of the blended fuel is low; When the warm-up of the engine is not completed, the operating point corresponding to the required output is calculated using a predetermined specific operating line regardless of the alcohol concentration of the mixed fuel; When the warm-up of the engine is completed and the torque distributed from the engine to the first motor generator through the power distribution mechanism exceeds the rated torque of the first motor generator, the engine torque is limited using an operating line selected according to the alcohol concentration of the mixed fuel so that the torque does not exceed the rated torque. Engine control device.

2. When the alcohol concentration of the mixed fuel is high, the operating point set in accordance with the required output is changed to a higher torque side and a lower rotation speed side than when the alcohol concentration of the mixed fuel is low, on the condition that the alcohol concentration of the mixed fuel is equal to or higher than a predetermined set concentration and the warm-up of the engine is completed. The engine control device according to claim 1.

3. Acquires engine coolant temperature detected by a water temperature sensor, When the acquired engine coolant temperature is equal to or higher than a predetermined set temperature, it is determined that the engine has been warmed up. The engine control device according to claim 1.

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