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CN-117597248-B - Hybrid vehicle

CN117597248BCN 117597248 BCN117597248 BCN 117597248BCN-117597248-B

Abstract

A control unit (112) determines whether or not the total value of the required engine output P ENG‑RQ and the maximum power running output P GEN‑DRV of the generator is smaller than a predetermined determination threshold value P TH when starting an engine (107), and calculates the required torque of the engine by calculating the torque feedback correction amount of the engine based on the deviation from the target engine speed when the total value is smaller than the predetermined determination threshold value.

Inventors

  • Naoto Dai
  • OKUMA TAKAHIRO

Assignees

  • 三菱自动车工业株式会社

Dates

Publication Date
20260508
Application Date
20220616
Priority Date
20210728

Claims (9)

  1. 1. A hybrid vehicle is provided with an engine, a generator mechanically connected to an output shaft of the engine and capable of performing a regenerative operation or a power running operation, a battery that accumulates electric power generated during the regenerative operation of the generator and supplies electric power during the power running operation of the generator, a motor that converts electric power supplied from the battery into driving force of a driving wheel, and a control unit that controls the engine, the generator, and the motor, When the engine is started, the control unit determines whether or not a total value of a required output of the engine and a maximum output of the power running of the generator is smaller than a predetermined determination threshold, When the total value is smaller than the predetermined determination threshold value, the control unit calculates a torque feedback correction amount of the engine based on a deviation from a target rotation speed of the engine, and controls a required torque of the engine.
  2. 2. The hybrid vehicle of claim 1, wherein, The predetermined determination threshold value is set in advance depending on the cooling water temperature of the engine for each target rotation speed of the engine.
  3. 3. The hybrid vehicle of claim 1, wherein, The control unit further determines whether or not the total value is smaller than a value obtained by adding a hysteresis set value to the predetermined determination threshold, When the total value is smaller than a value obtained by adding a hysteresis set value to the predetermined determination threshold value, the control unit calculates a torque feedback correction amount of the engine based on a deviation from a target rotation speed of the engine, and controls the required torque of the engine.
  4. 4. The hybrid vehicle of claim 2, wherein, The control unit further determines whether or not the total value is smaller than a value obtained by adding a hysteresis set value to the predetermined determination threshold, When the total value is smaller than a value obtained by adding a hysteresis set value to the predetermined determination threshold value, the control unit calculates a torque feedback correction amount of the engine based on a deviation from a target rotation speed of the engine, and controls the required torque of the engine.
  5. 5. The hybrid vehicle of claim 1, wherein, The control unit decreases a torque feedback correction amount of the engine by a predetermined ratio at least at the end of the requested torque control of the engine.
  6. 6. The hybrid vehicle of claim 2, wherein, The control unit decreases a torque feedback correction amount of the engine by a predetermined ratio at least at the end of the requested torque control of the engine.
  7. 7. A hybrid vehicle as set forth in claim 3, wherein, The control unit decreases a torque feedback correction amount of the engine by a predetermined ratio at least at the end of the requested torque control of the engine.
  8. 8. The hybrid vehicle of claim 4, wherein, The control unit decreases a torque feedback correction amount of the engine by a predetermined ratio at least at the end of the requested torque control of the engine.
  9. 9. The hybrid vehicle according to any one of claim 1 to 8, wherein, The predetermined determination threshold value is an output value corresponding to a maximum torque error including a friction torque error of an output shaft of the engine.

Description

Hybrid vehicle Technical Field The present invention relates to a control technique for a hybrid vehicle provided with a motor (electric motor) and an engine (internal combustion engine). Background It is known that rechargeable secondary batteries (batteries) have reduced output performance at low temperatures, and in particular, in plug-in and series hybrid vehicles, it is considered to be an important problem that the driving force is insufficient due to reduced battery output. In order to solve such a driving force deficiency, for example, patent document 1 proposes a control method of temporarily increasing an engine torque to increase a power generation amount of a generator when a driver requests an output greater than a predetermined value by an accelerator operation at a low temperature at which an output performance of a battery is lowered. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2019-162930 Technical problem to be solved by the invention In the control method disclosed in patent document 1, when the driver's requested output is increased to a predetermined value or more at a low temperature, the engine torque is increased to suppress a decrease in power performance. Therefore, the control operation is dependent on the accelerator operation by the driver and operates only during running. However, when traveling in the EV mode or when stopping, the engine may be started to generate power regardless of the accelerator operation by the driver. At this time, the rotation speed of the engine cannot be maintained at the target value in a state where the battery output is reduced, and the rotation speed is reduced, and there is a possibility that the engine stall (extinction) occurs. As will be described in detail later, the inventors of the present application found that this decrease in engine speed is caused by a torque error between engine-generators due to a difference in the rate of rise of water temperature and oil temperature of the engine (see fig. 3). Since the engine required output is maintained at a predetermined value without performing the accelerator operation, the normal control can be maintained by the power running assist of the generator at an output exceeding the torque error as long as the power running output of the generator is sufficient. However, since the power running output of the generator is obtained by taking out electric power from the battery and driving the generator by the motor, the rotation speed of the engine is increased, and therefore, as the battery output is reduced, the power running output of the generator is also reduced, and becomes zero at an extremely low temperature or when the battery is deteriorated. As described above, when the power running output of the generator decreases, the total value of the engine required output and the power running output of the generator decreases due to the torque error, and the engine speed decreases, and eventually the flameout occurs. Hereinafter, description will be made with reference to fig. 1. In fig. 1, when traveling in the EV traveling mode, the engine is started at time t1, and the vehicle shifts to the series traveling at time t 2. At the time of engine start, the motor is driven by the generator, and the engine speed is increased to reach the target speed. However, when the driver does not operate the accelerator, the engine required output is a constant value, and when the power running output of the generator decreases with a decrease in the battery output and the assist of the generator decreases, the total value of the engine required output and the power running output of the generator starts to be lower than the torque error. Thus, the engine speed does not maintain the target and starts to gradually decrease, and at time tx, the engine is stopped and flameout occurs. In the control method that depends on the accelerator operation by the driver as in patent document 1 described above, such flameout cannot be prevented. Disclosure of Invention The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a hybrid vehicle capable of preventing flameout by maintaining the engine speed even when the battery is in a reduced output state. Technical means for solving the technical problems According to an embodiment of the present invention for achieving the above object, a hybrid vehicle includes an engine, a generator mechanically connected to an output shaft of the engine and capable of performing a regenerative operation or a power running operation, a battery that accumulates electric power generated during the regenerative operation of the generator and supplies electric power during the power running operation of the generator, a motor that converts electric power supplied from the battery into driving force of a driving wheel, and a control unit that controls the engine, th