JP2017121896A - Hybrid vehicle and control method for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle and a control method for the hybrid vehicle, capable of suppressing vibration of an engine at stop of the engine.SOLUTION: A hybrid vehicle includes: a hybrid system 30 having a motor generator 31 connected to an output shaft 13 for transmitting power of an engine 10; and a control device 80. In the hybrid vehicle, the control device controls torque of the motor generator connected to the output shaft of the engine on the basis of a crank angle of the engine so that a piston of the engine is stopped at a position other than a top dead center when receiving an engine stop request that is a request for stopping the engine.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hybrid vehicle including a hybrid system having a motor generator connected to an output shaft that transmits engine power, and a method for controlling the hybrid vehicle.

  In recent years, a hybrid vehicle (hereinafter referred to as “HEV”) including a hybrid system having an engine and a motor generator that are controlled in combination according to the driving state of the vehicle has attracted attention from the viewpoint of improving fuel efficiency and environmental measures. . In this HEV, driving force is assisted by a motor generator when the vehicle is accelerated or started, while regenerative power generation is performed by the motor generator during inertia traveling or braking (see, for example, Patent Document 1). In recent years, HEVs in which a motor generator is connected to an output shaft for transmitting engine power have been developed.

  By the way, when the engine is stopped, the vibration of the engine when the engine is stopped may increase depending on the stop position (crank angle) of the piston. Specifically, when the piston stops at the top dead center, the vibration of the engine increases. This is considered that when the piston stops at the top dead center position, a large vibration occurs due to the piston returning to the bottom dead center side by reaction from the top dead center position. Note that the vibration when the engine is stopped generally tends to be larger in a diesel engine than in a gasoline engine. However, no technology has been developed for suppressing vibration when the engine is stopped.

JP 2002-238105 A

  The present invention has been made in view of the above, and an object thereof is to provide a hybrid vehicle and a hybrid vehicle control method capable of suppressing engine vibration when the engine is stopped.

  In order to achieve the above object, a hybrid vehicle of the present invention is a hybrid vehicle including a hybrid system having a motor generator connected to an output shaft that transmits engine power, and a control device. When the engine stop request, which is a request to stop the engine, is received, the output shaft of the engine is based on the crank angle of the engine so that the piston of the engine stops at a position other than the top dead center. The torque of the motor generator connected to is controlled.

  According to the present invention, when the engine stop request is received, the engine piston can be stopped at a position other than the top dead center by controlling the torque of the motor generator as described above. The vibration of the engine can be suppressed.

In the above configuration, the control device controls the torque of the motor generator connected to the output shaft of the engine based on the crank angle of the engine.
The engine crank angle may be estimated based on the rotation speed of the motor generator, and the torque of the motor generator connected to the output shaft of the engine may be controlled based on the estimated crank angle of the engine. .

  Here, in general, it is not easy to accurately detect the crank angle by the crank angle sensor. On the other hand, it is relatively easy to detect the rotational speed of the motor generator with high accuracy by a motor rotational speed sensor that detects the rotational speed of the motor generator. Therefore, estimating the crank angle of the engine based on the rotation speed of the motor generator can be performed more easily and accurately than directly detecting the crank angle with a crank angle sensor. Therefore, according to the above configuration, it is easier to accurately estimate the crank angle and control the torque of the motor generator more accurately than to control the torque of the motor generator based on the crank angle directly detected by the crank angle sensor. It can be controlled well. As a result, the piston can be easily stopped with high accuracy at a position other than the top dead center.

  According to another aspect of the present invention, there is provided a hybrid vehicle control method according to the present invention, comprising: a hybrid system having a motor generator connected to an output shaft that transmits engine power; When the engine stop request, which is a request to stop, is received, the piston of the engine is connected to the output shaft of the engine based on the crank angle of the engine so as to stop at a position other than the top dead center. The torque of the motor generator is controlled.

  According to the present invention, when the engine stop request is received, the engine piston can be stopped at a position other than the top dead center by controlling the torque of the motor generator as described above. The vibration of the engine can be suppressed.

  In the above method, when controlling the torque of the motor generator connected to the output shaft of the engine based on the crank angle of the engine, the crank angle of the engine is estimated based on the rotational speed of the motor generator, The torque of the motor generator connected to the output shaft of the engine may be controlled based on the estimated crank angle of the engine.

  According to the above method, it is possible to easily estimate the crank angle with higher accuracy and to easily increase the torque of the motor generator than when controlling the torque of the motor generator based on the crank angle directly detected by the crank angle sensor. It can be controlled with high accuracy. As a result, the piston can be easily stopped with high accuracy at a position other than the top dead center.

  ADVANTAGE OF THE INVENTION According to this invention, when an engine stop request | requirement is received, an engine piston can be stopped in positions other than a top dead center, and the vibration of an engine at the time of an engine stop can be suppressed.

It is a block diagram of the hybrid vehicle which consists of embodiment of this invention. It is a flowchart which shows an example of the control process at the time of a stop by a control apparatus.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a hybrid vehicle according to an embodiment of the present invention. This hybrid vehicle (hereinafter referred to as “HEV”) is a vehicle including not only a normal passenger car but also a bus, a truck, etc., and a hybrid having an engine 10 and a motor generator 31 that are controlled in combination according to the driving state of the vehicle. A system 30 is provided.

  In the engine 10, the crankshaft 13 is rotationally driven by thermal energy generated by the combustion of fuel in a plurality (four in this example) of cylinders 12 formed in the engine body 11. The engine 10 is a diesel engine or a gasoline engine. The rotational power of the crankshaft 13 is transmitted to the transmission 20 through a clutch 14 (for example, a wet multi-plate clutch) connected to one end of the crankshaft 13.

  The transmission 20 uses an AMT or an AT that automatically shifts to a target shift speed determined based on the HEV operating state and preset map data using the shift actuator 21. The transmission 20 is not limited to an automatic transmission type such as AMT, and may be a manual type in which a driver manually changes gears.

  The rotational power changed by the transmission 20 is transmitted to the differential 23 through the propeller shaft 22 and distributed to each of the pair of drive wheels 24 as drive power.

  The hybrid system 30 includes a motor generator 31, an inverter 35, a high voltage battery 32, a DC / DC converter 33, and a low voltage battery 34 that are electrically connected to the motor generator 31 in order.

  Preferred examples of the high voltage battery 32 include a lithium ion battery and a nickel metal hydride battery. The low voltage battery 34 is a lead battery.

  The DC / DC converter 33 has a function of controlling the charge / discharge direction and the output voltage between the high voltage battery 32 and the low voltage battery 34. The low voltage battery 34 supplies power to various vehicle electrical components 36.

  Various parameters in the hybrid system 30 such as a current value, a voltage value, and an SOC are detected by a BMS 39 (battery management system). The BMS 39 transmits the detection result to the control device 80.

  The motor generator 31 is a metal made around a first pulley 15 attached to a rotating shaft 37 and a second pulley 16 attached to the other end of the crankshaft 13 that is an output shaft of the engine body 11. Power is transmitted to and from the engine 10 through the chain 17. That is, the first pulley 15, the second pulley 16, and the chain 17 have a function as a power transmission mechanism that transmits power between the output shaft that transmits the power of the engine 10 and the rotating shaft 37 of the motor generator 31. ing.

  However, the configuration of the power transmission mechanism is not limited to this. For example, the power transmission mechanism transmits power via a plurality of gears instead of the first pulley 15, the second pulley 16, and the chain 17. It is also possible to use a mechanism that does this. As described above, by using the chain 17 and the plurality of gears as the power transmission mechanism, power transmission between the engine 10 and the motor generator 31 can be performed without causing slippage.

Further, the output shaft of the engine main body 11 connected to the motor generator 31 is not limited to the crankshaft 13, and may be, for example, a transmission shaft or the propeller shaft 22 between the engine main body 11 and the transmission 20.

  The motor generator 31 has a function of cranking instead of a starter motor (not shown) that starts the engine body 11.

  The HEV also includes a motor rotation speed sensor 102 as a sensor for detecting the rotation speed of the motor generator 31 (specifically, the rotation speed of the rotation shaft 37). The motor rotation speed sensor 102 transmits the detection result to the control device 80.

  The hybrid system 30 described above is controlled by the control device 80. Specifically, the hybrid system 30 is controlled by the control device 80 to assist at least a part of the driving force by the motor generator 31 supplied with power from the high voltage battery 32 when the HEV starts or accelerates. On the other hand, during inertial running or braking, regenerative power generation is performed by the motor generator 31, and excess kinetic energy is converted into electric power to charge the high voltage battery 32.

  In addition to the hybrid system 30, the control device 80 controls disengagement and connection of the clutch 14 and also controls the gear stage of the transmission 20 by controlling the shift actuator 21. The control device 80 includes a CPU having a function as a control unit for executing various control processes, and a ROM, a RAM, and the like having a function as a storage unit for storing various data and programs used for the operation of the CPU. A microcomputer is provided.

  In addition, when the control device 80 according to the present embodiment receives an engine stop request that is a request to stop the engine 10, the piston (not shown) of the engine 10 stops at a position other than the top dead center. Further, the torque of the motor generator 31 connected to the output shaft of the engine 10 (in this embodiment, the crankshaft 13) is controlled based on the crank angle of the engine 10 (hereinafter, this control process is referred to as a stop time control process).

  Further, the control device 80 controls the torque of the engine 10 based on the rotational speed of the motor generator 31 when controlling the torque of the motor generator 31 based on the crank angle of the engine 10 as described above. The torque of the motor generator 31 is controlled based on the estimated crank angle. The details of the control processing at the time of stop will be described as follows using a flowchart.

  FIG. 2 is a flowchart showing an example of the stop time control process by the control device 80. The control unit of the control device 80 repeatedly executes the flowchart of FIG. 2 at a predetermined cycle. In step S10, the control unit determines whether an engine stop request has been received. The specific content of the engine stop request is not particularly limited. For example, it may be an engine stop request transmitted by the control device 80 when the engine 10 is idle-stopped, and the driver stops the engine 10. Therefore, an engine stop command from the driver may be used as in the case where the engine stop switch is pressed.

  When it determines with NO by step S10, a control part returns to the start of a flowchart (return).

On the other hand, when it is determined YES in step S10 (when a stop request is received), the control unit estimates the crank angle based on the rotation speed of the motor generator 31, and the piston is determined based on the estimated crank angle. Based on the estimated crank angle, the torque of the motor generator 31 connected to the output shaft of the engine 10 is controlled so as to stop at a position other than the top dead center (step S20). The position where the piston stops is not particularly limited as long as it is a position other than the top dead center, but in the present embodiment, as an example, a predetermined position between the top dead center and the bottom dead center, Specifically, an intermediate position between the top dead center and the bottom dead center is used.

  In addition, when estimating the crank angle in step S20, the control unit specifically executes this by the following method. First, a first arithmetic expression for calculating the rotational speed of the engine 10 from the rotational speed of the motor generator 31 is stored in advance in the storage unit (for example, ROM) of the control device 80, and the engine 10 is calculated from the rotational speed of the engine 10. A second arithmetic expression for calculating the crank angle is also stored in advance.

  Therefore, in step S20, the control unit acquires the rotation speed (rpm) of the motor generator 31 detected by the motor rotation speed sensor 102, and uses the first arithmetic expression based on the acquired rotation speed of the motor generator 31. The rotational speed of the engine 10 is calculated, and the crank angle is calculated using the second arithmetic expression based on the calculated rotational speed of the engine 10. And a control part acquires this calculated crank angle as a crank angle (estimated crank angle) of step S20. However, the specific estimation method of the crank angle by the control unit may be any method that can estimate the crank angle based on the rotation speed of the motor generator 31, and is not limited to this.

  In addition, when the control unit stops the piston at a position other than the top dead center in step S20, specifically, the position of the piston between the top dead center and the bottom dead center (in the present embodiment, an intermediate position). Stop at.

  A specific example is as follows. When there is an engine stop request in step S10, and the fuel injection of the engine 10 is thereby stopped, the rotational speed of the engine 10 decreases mainly due to engine friction (that is, the engine 10 moves in the direction of stopping). In this embodiment, the torque control of the motor generator 31 in step S20 is added to the decrease in the rotational speed of the engine 10 due to the engine friction, so that the piston position that should normally stop at random is other than the top dead center. Is quickly stopped at the position (for example, an intermediate position).

  According to the present embodiment described above, when the engine stop request is received, the motor generator 31 connected to the output shaft of the engine 10 based on the crank angle so that the piston stops at a position other than the top dead center. By controlling the torque, the piston can be stopped at a position other than the top dead center. Thereby, compared with the case where a piston stops at a top dead center, vibration of engine 10 at the time of stop of engine 10 can be controlled.

  The control device 80 according to the present embodiment estimates the crank angle based on the rotation speed of the motor generator 31 and controls the estimated crank angle when controlling the torque of the motor generator 31 based on the crank angle in step S20. Although the torque of the motor generator 31 is controlled based on the angle, the specific content of the torque control based on the crank angle is not limited to this. For example, the control device 80 may directly detect the crank angle using a crank angle sensor and perform torque control based on the directly detected crank angle.

However, in general, it is not easy to accurately detect the crank angle by the crank angle sensor. On the other hand, it is relatively easy to detect the rotational speed of the motor generator 31 with high accuracy by the motor rotational speed sensor 102 that detects the rotational speed of the motor generator 31. Therefore, as in the present embodiment, estimating the crank angle of the engine 10 based on the rotational speed of the motor generator 31 can be performed more easily and accurately than directly detecting the crank angle with a crank angle sensor. Therefore, according to the above configuration, the torque of the motor generator 31 can be easily estimated and the torque of the motor generator 31 can be easily estimated more accurately than the control of the torque of the motor generator 31 based on the crank angle directly detected by the crank angle sensor. Can be controlled with high accuracy. As a result, the piston can be easily stopped with high accuracy at a position other than the top dead center.

  Further, when the engine 10 has a plurality of cylinders 12 as in this embodiment, the control device 80 may stop the positions of the pistons of all the cylinders 12 at a position other than the top dead center. The position of the piston of only the cylinder 12 may be stopped at a position other than the top dead center. However, the case where the pistons of all the cylinders 12 are stopped at positions other than the top dead center is preferable in that vibrations of the engine 10 when the engine 10 is stopped can be more effectively suppressed.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. Is possible.

10 Engine 13 Crankshaft (output shaft)
30 Hybrid system 31 Motor generator 80 Control device

Claims (4)

In a hybrid vehicle including a hybrid system having a motor generator connected to an output shaft that transmits engine power, and a control device,
When the control device receives an engine stop request, which is a request to stop the engine, the engine based on the crank angle of the engine so that the piston of the engine stops at a position other than the top dead center. A hybrid vehicle that controls torque of the motor generator connected to the output shaft.   The control device estimates the crank angle of the engine based on the rotational speed of the motor generator when controlling the torque of the motor generator connected to the output shaft of the engine based on the crank angle of the engine. The hybrid vehicle according to claim 1, wherein the torque of the motor generator connected to the output shaft of the engine is controlled based on the estimated crank angle of the engine. In a method for controlling a hybrid vehicle comprising a hybrid system having a motor generator connected to an output shaft for transmitting engine power,
When an engine stop request, which is a request to stop the engine, is received, the engine output shaft of the engine is based on the crank angle of the engine so that the piston of the engine stops at a position other than the top dead center. A method for controlling a hybrid vehicle, comprising controlling torque of the connected motor generator.   In controlling the torque of the motor generator connected to the output shaft of the engine based on the crank angle of the engine, the crank angle of the engine is estimated based on the rotation speed of the motor generator, and the estimated The hybrid vehicle control method according to claim 3, wherein a torque of the motor generator connected to the output shaft of the engine is controlled based on an engine crank angle.

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