JP6167922B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device for a hybrid vehicle, and more particularly to a technical field of a vehicle control device for a hybrid vehicle equipped with a lean-burnable engine.

  As an apparatus of this type, for example, an upper limit value of a voltage value applied to a motor / generator coupled to be capable of transmitting torque to an engine output shaft is set, and according to the upper limit value of the set voltage value, An apparatus has been proposed in which an upper limit value of the output shaft rotational speed of the motor / generator is set and the motor / generator is controlled so that the output shaft rotational speed is smaller than the upper limit value (see Patent Document 1).

  In a hybrid vehicle, when the gear shift of the transmission is being performed, the fluctuation rate of the engine speed is set to a smaller value than the rate value when the gear shift is not being performed. And the apparatus which sets the upper limit rotation speed of an engine is proposed (refer patent document 2).

  Further, in a hybrid vehicle, a technique has been proposed in which the increase or decrease in torque in the vicinity of the lean limit operation of the engine is offset by the increase or decrease in engine speed and the increase or decrease in motor / generator speed (see Patent Document 3).

JP 2009-012679 A JP 2007-237923 A JP 2006-090138 A

  When the engine is capable of lean combustion, in the control method such as the technique described in Patent Document 1 described above, when the lean combustion with relatively large fluctuations in engine torque is being performed, the motor / generator has an upper limit rotational speed. There is a technical problem that there is a possibility of exceeding. With the techniques described in Patent Documents 2 and 3, it is difficult to solve this problem.

  The present invention has been made in view of the above problems, for example, and an object of the present invention is to provide a vehicle control device that can suppress over-rotation of a motor / generator in a hybrid vehicle.

In order to solve the above-described problem, a vehicle control device of the present invention includes an engine capable of lean combustion, an electric motor, and a power distribution mechanism having a planetary gear, and the first rotation element of the power distribution mechanism is the engine. A second rotation element of the power distribution mechanism is connected to the electric motor, and a third rotation element of the power distribution mechanism is a vehicle control device for a hybrid vehicle connected to drive wheels, and relates to the engine The upper limit rotational speed of the electric motor is set according to the air-fuel ratio and the shift position related to the transmission of the hybrid vehicle, and the set upper limit rotational speed is lowered as the output change related to the engine increases. , and, as the air-fuel ratio change is large according to the engine such that said set upper limit rotation speed decreases, change to correct the upper limit rotational speed of the set Equipped with a stage.

  According to the vehicle control device of the present invention, the vehicle control device is mounted on a hybrid vehicle. The hybrid vehicle includes an engine capable of lean combustion, an electric motor, and a power distribution mechanism having a planetary gear. The first rotation element of the power distribution mechanism is connected to the engine, the second rotation element is connected to the electric motor, and the third rotation element is connected to the drive wheel.

For example, the changing means including a memory, a processor, etc. sets the upper limit number of rotations of the electric motor according to the air-fuel ratio related to the engine and the shift position related to the transmission of the hybrid vehicle, and as the output change related to the engine increases The set upper limit rotational speed is corrected so that the set upper limit rotational speed becomes lower and the set upper limit rotational speed becomes lower as the air-fuel ratio change related to the engine becomes larger.

  According to the inventor's research, the following matters have been found. That is, for example, when the engine output fluctuation is large due to the air-fuel ratio at the time of lean combustion, for example, when the engine is in transition, such as at the time of shifting, there is a possibility that the rotational speed of the motor will be over-rotated.

  Therefore, in the present invention, as described above, the upper limit rotational speed of the electric motor is controlled by the changing means. If comprised in this way, since the upper limit rotation speed of the electric motor according to the driving | running state of an engine can be set, it can suppress that this electric motor becomes an overspeed.

  The vehicle control device according to the present invention may further control the engine so that the air-fuel ratio related to the engine does not change during reverse climbing of the hybrid vehicle. Alternatively, the vehicle control device may control the engine so that the air-fuel ratio of the engine does not change when shifting the transmission of the hybrid vehicle.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

It is a conceptual diagram which shows the structure of the hybrid vehicle which concerns on embodiment. It is a figure which shows an example of the operating line of an engine when a horizontal axis | shaft is an engine speed and a vertical axis | shaft is an engine torque. It is an example of the map which prescribes | regulates the relationship between the air fuel ratio which concerns on an engine, and the upper limit rotation speed of a motor generator. It is an example of the map which prescribes | regulates the relationship between the output variation amount which concerns on an engine, and the correction amount of the upper limit rotation speed of a motor generator. It is an example of the map which prescribes | regulates the relationship between the variation | change_quantity of the air fuel ratio which concerns on an engine, and the correction amount of the upper limit rotation speed of a motor generator. It is a flowchart which shows the vehicle control process which concerns on embodiment.

  An embodiment according to a vehicle control device of the present invention will be described with reference to the drawings.

(Configuration of hybrid vehicle)
First, the structure of the hybrid vehicle which concerns on embodiment is demonstrated with reference to FIG. FIG. 1 is a conceptual diagram illustrating a configuration of a hybrid vehicle according to an embodiment.

  In FIG. 1, the hybrid vehicle 1 includes an engine 10 and motor / generators MG1 and MG2 connected to the engine 10 via a power distribution mechanism 14, respectively. The motor / generator MG1 is mainly used for control of the engine 10 and power generation. On the other hand, motor generator MG2 is mainly used for driving hybrid vehicle 1 and for regenerative braking.

  The power distribution mechanism 14 includes a planetary gear mechanism. The crankshaft of the engine 10 is connected to the carrier of the planetary gear mechanism. The rotation shaft of the motor / generator MG1 is connected to the sun gear of the planetary gear mechanism. The rotation shaft of the motor / generator MG2 is connected to an output shaft from which the rotational power of the ring gear of the planetary gear mechanism is output.

  The power distribution mechanism 14, the motor / generator MG1, and the motor / generator MG2 constitute a continuously variable transmission. The hybrid vehicle 1 is further arranged in a power transmission path between the continuously variable transmission unit and drive wheels (not shown), and is connected in series via the output shaft of the continuously variable transmission unit. Part 15 is provided. Since various known modes can be applied to the stepped transmission unit 15, the detailed description thereof is omitted. In addition, various known modes can be applied to the control methods of the continuously variable transmission unit and the stepped transmission unit 15, and thus the detailed description thereof is omitted.

  The engine 10, the motor / generator MG1, the motor / generator MG2, the power distribution mechanism 14, and the stepped transmission unit 15 are actually arranged on the same axis. However, in FIG. Etc. are not arranged on the same axis.

  An intake passage 11 and an exhaust passage 12 are connected to the engine 10. In the intake passage 11, an air flow meter 21, an intake throttle valve 22, a compressor 23 c of a turbocharger 23 and an intercooler 24 are provided. In the exhaust passage 12, a turbine 23 t of the turbocharger 23, a start converter 25 and an aftertreatment device 26 are provided.

  The engine 10 is further provided with a low pressure EGR device that recirculates a part of the exhaust gas flowing in the exhaust passage 12 to the intake passage 11 at a low pressure. The low pressure EGR device communicates the downstream side of the start converter 25 in the exhaust passage 12 and the upstream side of the aftertreatment device 26 with the downstream side of the intake throttle valve 22 and the upstream side of the compressor 23c in the intake passage 11. A passage 13 is provided. The low pressure EGR passage 13 is provided with an EGR cooler 17 and an EGR valve 28.

  The hybrid vehicle 1 further includes an engine ECU (Electronic Control Unit) 32 that controls the engine 10, an MGECU 33 that controls the motor generators MG 1 and MG 2, and outputs of various sensors provided in the hybrid vehicle 1. And the HVECU 31 that controls the engine ECU 32 and the MGECU 33 in an integrated manner.

  The “motor / generator MG1”, “carrier”, “sun gear”, and “ring gear” according to the embodiment are the “motor”, “first rotating element”, “second rotating element”, and It is an example of a “third rotation element”.

(Engine operation)
Next, the operation of the engine 10 will be described with reference to FIG. FIG. 2 is a diagram showing an example of an engine operating line when the horizontal axis is the engine speed and the vertical axis is the engine torque.

  As shown in FIG. 2, the engine 10 according to the embodiment employs various combustion modes according to the power required for the engine 10 (hereinafter, referred to as “engine required power” as appropriate). Then, the engine ECU 32 basically controls the engine 10 according to the engine required power so that the operating point of the engine 10 changes, for example, along an operation line (see solid line) that is a fuel efficiency optimum line. If comprised in this way, a fuel consumption can be improved and it is very advantageous practically.

  Here, since various known modes can be applied to the method for switching the combustion mode of the engine 10, a detailed description thereof will be omitted.

  In FIG. 2A, “NA stoichiometric”, “NA lean”, “supercharging lean”, and “supercharging stoichiometric” are respectively “non-supercharging stoichiometric combustion mode” and “non-supercharging lean combustion mode”. ”,“ Supercharged lean combustion mode ”and“ supercharged stoichiometric combustion mode ”. Moreover, the broken line in FIG. 2 has shown the equal power curve.

(Vehicle control processing)
Next, vehicle control processing in the hybrid vehicle 1 configured as described above will be described with reference to FIGS. 3 to 6.

  In the HVECU 31 according to the embodiment, for example, in a memory (not shown), a map (see FIG. 3) that defines the relationship between the air-fuel ratio related to the engine 10 and the upper limit rotational speed of the motor / generator MG1, and the output related to the engine 10 A map (see FIG. 4) that defines the relationship between the change amount and the correction amount of the upper limit rotational speed of the motor / generator MG1, and the air-fuel ratio change amount related to the engine 10 and the correction amount of the upper limit rotational speed of the motor / generator MG1. A map that defines the relationship (see FIG. 5) is stored in advance.

  In the flowchart of FIG. 6, first, the HVECU 31 determines whether or not the gear position of the hybrid vehicle 1 is the “reverse position” (step S101). When it is determined that the vehicle is in the “reverse position” (step S101: Yes), the HVECU 31 determines that the hybrid vehicle 1 is on a gradient path with a certain gradient or more based on outputs from, for example, an inclination angle sensor, a gravitational acceleration sensor, and an acceleration sensor. It is determined whether or not the vehicle is climbed back (step S102).

  When it is determined that the vehicle is climbing up (step S102: Yes), the HVECU 31 instructs the engine ECU 32 not to switch the combustion mode of the engine 10 (step S103). Next, the HVECU 31 determines the motor 10 based on the air-fuel ratio of the engine 10 and a map (see the solid line corresponding to “reverse” in FIG. 3) that defines the relationship between the air-fuel ratio and the upper limit rotational speed of the motor generator MG1. Set the upper limit rotational speed of the generator MG1 (step S105).

  Subsequently, the HVECU 31 is set based on the output change amount of the engine 10 and a map (see FIG. 4) that defines the relationship between the output change amount and the correction amount of the upper limit rotational speed of the motor / generator MG1. The upper limit rotational speed of the motor / generator MG1 is corrected (step S106).

  Before and after the process of step S106, the HVECU 31 defines a relationship between the air-fuel ratio change amount of the engine 10, and the relationship between the air-fuel ratio change amount and the correction amount of the upper limit rotational speed of the motor / generator MG1 (see FIG. 5). Based on the above, the set upper limit rotational speed of the motor / generator MG1 is corrected (step S107). Thereafter, the HVECU 31 instructs the MGECU 33 of the corrected upper limit rotational speed of the motor / generator MG1, and returns the process.

  If it is determined in the processing of step S102 that the vehicle is not climbing (step S102: No), the HVECU 31 appropriately changes the combustion mode while the operating point of the engine 10 transitions along the optimum operating line (see FIG. 2). The engine ECU 32 is instructed to switch (step S104). Next, the HVECU 31 performs the process of step S105.

  If it is determined in step S101 that it is not the “reverse position” (step S101: No), the HVECU 31 determines whether or not a shift is being performed (step S108). If it is determined that the speed is being changed (step S108: Yes), the engine ECU 32 is instructed not to switch the combustion mode of the engine 10 (step S109). Next, the HVECU 31 determines the motor 10 based on the air-fuel ratio of the engine 10 and a map that defines the relationship between the air-fuel ratio and the upper limit rotational speed of the motor generator MG1 (see the solid line corresponding to “forward” in FIG. 3). Set the upper limit rotational speed of the generator MG1 (step S111).

  Subsequently, the HVECU 31 is set based on the output change amount of the engine 10 and a map (see FIG. 4) that defines the relationship between the output change amount and the correction amount of the upper limit rotational speed of the motor / generator MG1. The upper limit rotational speed of the motor / generator MG1 is corrected (step S112).

  Before and after the process of step S106, the HVECU 31 defines an air-fuel ratio change amount of the engine 10 and a relationship between the air-fuel ratio change amount and the correction amount of the upper limit rotational speed of the motor / generator MG1 (see FIG. 5). Based on the above, the set upper limit rotational speed of the motor / generator MG1 is corrected (step S113). Thereafter, the HVECU 31 instructs the MGECU 33 of the corrected upper limit rotational speed of the motor / generator MG1, and returns the process.

  If it is determined in step S108 that the gear is not being shifted (step S108: No), the HVECU 31 determines that the HVECU 31 appropriately changes the operating point of the engine 10 along the optimum operating line (see FIG. 2). The engine ECU 32 is instructed to switch the combustion mode (step S110). Next, the HVECU 31 performs the process of step S111.

  The correction amount of the upper limit rotational speed of the motor / generator MG1 according to the output change amount of the engine 10 (see FIG. 4) and the correction of the upper limit rotational speed of the motor / generator MG1 according to the air fuel ratio change amount of the engine 10 The amount (see FIG. 5) may be changed according to the air-fuel ratio of the engine 10.

  The “HVECU 31”, “engine ECU 32”, and “MG ECU 33” according to the embodiment are examples of the “vehicle control device” and the “changing unit” according to the present invention.

  The power distribution mechanism 14 according to the embodiment is not limited to a mechanism having three rotating elements, but has, for example, a plurality of differential mechanisms (for example, a plurality of planetary gear mechanisms), and produces a differential action 4. Other configurations such as a mechanism having two rotating elements are also applicable.

  The present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification. Is also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle, 10 ... Engine, 11 ... Intake passage, 12 ... Exhaust passage, 13 ... Low-pressure EGR passage, 14 ... Power distribution mechanism, 15 ... Stepped transmission part, 31 ... HVECU, 32 ... Engine ECU, 33 ... MGECU , MG1, MG2 ... Motor generator

Claims (1)

A lean combustion engine, an electric motor, and a power distribution mechanism having a planetary gear,
A hybrid vehicle in which a first rotation element of the power distribution mechanism is connected to the engine, a second rotation element of the power distribution mechanism is connected to the electric motor, and a third rotation element of the power distribution mechanism is connected to drive wheels. Vehicle control apparatus,
The upper limit rotational speed of the electric motor is set according to the air-fuel ratio related to the engine and the shift position related to the transmission of the hybrid vehicle, and the set upper limit rotational speed increases as the output change related to the engine increases. And changing means for correcting the set upper limit rotational speed such that the set upper limit rotational speed becomes lower as the air-fuel ratio change related to the engine becomes larger. Vehicle control device.

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