JP2017140970A - Hybrid vehicle and control method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle and a control method for the same that suppress reduction in a torque transmitted to driving wheels during a travel in which fuel injection is suspended and only a motor generator is working, to enhance fuel efficiency.SOLUTION: A hybrid vehicle comprises a control device 81 configured to perform one of, a combination of two of, or all of controls including: a control for opening an intake bypass valve 131 of an intake bypass passage 130 of a compressor 58b disposed in an intake passage 55, during a travel in which fuel injection for an engine is suspended and only a motor generator is working; a control for opening an exhaust bypass valve 133 of an exhaust bypass passage 132 of a turbine 63b disposed in an exhaust passage 41; and a control for opening a waste gate valve 135 of a turbine 63a disposed in the exhaust passage 41.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hybrid vehicle and a control method therefor, and more specifically, suppresses a reduction in torque transmitted to drive wheels during traveling in a state where fuel injection is stopped and only a motor generator is driven. The present invention relates to a hybrid vehicle that improves fuel consumption and a control method thereof.

  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. Yes. 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 deceleration (for example, see Patent Document 1).

  Further, in HEV, there is a case where the motor alone traveling that stops the fuel injection of the engine and drives only the motor generator may be performed. However, at this time, when a part of the torque transmitted from the motor generator is transmitted to the engine via the clutch, there is a problem that the torque for driving the motor alone is reduced due to engine friction. .

JP 2002-238105 A

  It is an object of the present invention to reduce the engine friction during traveling in a state where fuel injection is stopped and only the motor generator is driven, so that the torque for driving the motor alone transmitted to the drive wheels is reduced. The present invention provides a hybrid vehicle and a control method therefor that can suppress reduction due to engine friction and improve fuel efficiency.

  The hybrid vehicle of the present invention that achieves the above object is a hybrid vehicle having a hybrid system having an engine and a motor generator, which are power sources for driving the vehicle, and a control device. An intake bypass valve that adjusts the flow rate of intake air that passes through an intake bypass passage that bypasses the compressor disposed in the passage, and an exhaust gas flow rate that passes through an exhaust bypass passage that bypasses the turbine disposed in the exhaust passage of the engine. One of the exhaust bypass valve to be adjusted and the waste gate valve for adjusting the flow rate of the exhaust gas flowing into the turbine disposed in the exhaust passage of the engine, or a combination of all two, or all of them And the control device is configured to inject fuel from the engine. Of the control that opens the intake bypass valve, the control that opens the exhaust bypass valve, and the control that opens the wastegate valve while the vehicle is stopped and only the motor generator is driven. It is characterized by being configured to perform any one, any two combinations, or all.

  Further, the hybrid vehicle control method of the present invention that achieves the above object is the hybrid vehicle control method for stopping only fuel injection of the engine and driving only the motor generator during traveling. The step of opening an intake bypass valve that adjusts the flow rate of intake air that passes through the intake bypass passage that bypasses the compressor disposed in the engine, and the exhaust gas that passes through the exhaust bypass passage that bypasses the turbine disposed in the exhaust passage of the engine One of the step of opening the exhaust bypass valve for adjusting the flow rate and the step of opening with the wastegate valve for adjusting the flow rate of the exhaust gas flowing into the turbine disposed in the exhaust passage of the engine, or any one of them It is characterized by including two combinations or all It is a method.

  According to this hybrid vehicle and its control method, one of the controls for reducing the pump loss of the engine, or any two of them, while the fuel injection is stopped and only the motor generator is driven By performing the combination or all of them, it is possible to reduce engine friction during traveling when fuel injection is stopped.

  As a result, while the fuel injection of the engine is stopped and only the motor generator is running, the turbocharger is bypassed to reduce the loss due to engine friction. The reduction in torque transmitted from the engine to the drive wheels due to the loss of engine friction can be suppressed. As a result, it is possible to increase the efficiency with which the torque generated by the motor generator can be used as the driving force of the hybrid vehicle, thereby improving fuel efficiency.

It is a block diagram of the hybrid vehicle which consists of embodiment of this invention. It is a block diagram which illustrates the state at the time of the single stage supercharging of the engine of FIG. It is a block diagram which illustrates the state at the time of the multistage supercharging of the engine of FIG. It is a flowchart which illustrates the control method of the hybrid vehicle of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows 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 has an engine 10 and a motor generator 31 that are controlled in combination according to the driving state of the vehicle. A hybrid system 30 is provided. The HEV includes a plurality of turbochargers 57a and 57b.

  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 via a clutch 14 (for example, a wet multi-plate clutch) connected to one end of the crankshaft 13.

  The hybrid system 30 includes a motor generator 31, an inverter 35 that is electrically connected to the motor generator 31 in order, a high voltage battery 32 (for example, 48V), a DC / DC converter 33, and a low voltage battery 34 (for example, 12V). ).

  As the high voltage battery 32, a lithium ion battery or a nickel metal hydride battery is preferably exemplified. The low voltage battery 34 is a lead battery.

  The motor generator 31 is an endless shape wound around a first pulley 15 attached to the rotating shaft 37 and a second pulley 16 attached to the other end of the crankshaft 13 which is an output shaft of the engine body 11. Power is transmitted to and from the engine 10 via the belt-shaped member 17. Note that power can be transmitted using a gear box or the like instead of the first pulley 15, the second pulley 16 and the belt-like member 17. Further, the output shaft of the engine body 11 connected to the motor generator 31 is not limited to the crankshaft 13, and may be a transmission shaft between the engine body 11 and the transmission 20, for example.

  The motor generator 31 also has a function of performing cranking.

  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.

  2 and 3 illustrate a part of the configuration of the engine 10, more specifically, a configuration in which a plurality of turbochargers 57a and 57b are arranged. Hereinafter, the single-stage supercharging shown in FIG. 2 and the multistage supercharging shown in FIG. 3 will be described in more detail. In addition, in the valve | bulb, the state which the outline is open and the state where filling is closed is represented.

  The engine 10 includes a plurality of turbochargers 57a and 57b. The first turbocharger 57 a is formed by connecting a first compressor 58 a disposed upstream of the intake passage 55 and a first turbine 63 a disposed downstream of the exhaust passage 41. The second turbocharger 57 b is formed by connecting a second compressor 58 b disposed on the downstream side in the intake passage 55 and a second turbine 63 b disposed on the upstream side in the exhaust passage 41.

  Further, in the engine 10, an intake bypass passage 130 that bypasses the second compressor 58b, an intake bypass valve 131 that adjusts the flow rate of the intake air 56 that passes through the intake bypass passage 130, and a second turbine 63b. Exhaust bypass passage 132 that bypasses (detours) the exhaust bypass valve 133 that adjusts the flow rate of the exhaust gas 45 that passes through the exhaust bypass passage 132, and the wastegate passage that splits the exhaust gas 45 that flows into the first turbine 63a 134 and a wastegate valve 135 for adjusting the flow rate of the exhaust gas 45 flowing into the first turbine 63a.

  Switching between single-stage supercharging and multi-stage supercharging by the intake bypass valve 131 and the exhaust bypass valve 133 and adjustment of the wastegate valve 135 are controlled by the control device 81.

  The control devices 80 and 81 include a CPU that performs various processes, an internal storage device that can read and write programs and processing results used to perform the various processes, and various interfaces.

The control device 80 is a controller that controls the hybrid system 30. In this embodiment, the control device 80 controls the regeneration amount of the motor generator 31. The control device 81 is a controller that controls the engine 10, and in this embodiment, controls the opening of each valve and the like. These control devices 80 and 81 transmit and receive mutual data via a network (CAN) between the vehicle control devices.

  The control device 81 is connected to the intake bypass valve 131, the exhaust bypass valve 133, and the waste gate valve 135 via signal lines. The control device 81 is connected to an accelerator opening sensor 96 that detects an operation amount of the accelerator pedal 95 as an accelerator opening through a signal line.

  As an execution program of the control apparatus 80, the control program of the hybrid system 30 mentioned above can be illustrated. Moreover, as an execution program of the control apparatus 81, the supercharging switching control program of the intake bypass valve 131 and the exhaust bypass valve 133, and the flow rate adjustment control program of the wastegate valve 135 can be exemplified.

  The supercharging switching control program is an intake bypass valve 131 and an exhaust bypass valve 133 by open loop control (feedforward control) according to a target supercharging pressure based on the operating state of the engine 10, for example, the engine speed and the fuel injection amount. Are adjusted by closed loop control (feedback control) that compares the actual boost pressure detected by a MAP sensor (not shown) and the target boost pressure.

  Similarly, in the flow rate adjustment control program, after adjusting the opening degree of the wastegate valve 135 by open loop control according to the target boost pressure based on the operating state of the engine 10, the actual boost pressure, the target boost pressure, The degree of opening is adjusted by closed loop control.

  Specifically, at the time of single-stage supercharging, the intake bypass valve 131 and the exhaust bypass valve 133 are adjusted to fully open, and the second turbocharger 57b is bypassed. Further, the wastegate valve 135 is adjusted between the fully closed state and the intermediate opening degree, and the flow rate of the exhaust gas 45 flowing into the first turbocharger 57a is adjusted.

  As shown in FIG. 2, at the time of single-stage supercharging, the intake air 56 is sucked into the intake passage 55 from the outside, is compressed by the first compressor 58 a and becomes high temperature, and passes through the intake bypass passage 130. After bypassing the second compressor 58b, it is cooled by the intercooler 59. On the other hand, after a part of the exhaust gas 45 exhausted into the exhaust passage 41 bypasses the second turbine 63b through the exhaust bypass path 132, the first turbine 63a is driven. The rest bypasses the first turbine 63a via the wastegate passage 134.

  This avoids damage to the engine main body 11, the first turbocharger 57a, and the second turbocharger 57b due to excessive supercharging during traveling when the flow rate of the exhaust gas 45 is large, for example, when HEV starts or accelerates. doing.

  On the other hand, at the time of multi-stage supercharging, the intake bypass valve 131 and the exhaust bypass valve 133 are adjusted between fully closed to intermediate opening, and the wastegate valve 135 is adjusted to fully closed.

  As shown in FIG. 3, at the time of multistage supercharging, the intake air 56 is sucked into the intake passage 55 from the outside, and is compressed in the order of the first compressor 58 a and the second compressor 58 b in order, and cooled by the intercooler 59. Has been. On the other hand, the exhaust gas 45 exhausted into the exhaust passage 41 drives the second turbine 63b and the first turbine 63a in order.

  Accordingly, the actual supercharging pressure is increased by supercharging the turbochargers 57a and 57b in a state where the target supercharging pressure is high, for example, when HEV starts or accelerates.

  In such HEV, the control device 81 controls to open the intake bypass valve 131 while the fuel injection of the engine 10 is stopped and only the motor generator 31 is driven, and the exhaust bypass valve. The control for opening 133 and the control for opening the wastegate valve 135 are performed.

  More specifically, when the control device 80 determines that the fuel injection of the engine 10 is stopped and the motor generator 31 is running with the regenerative power generation, the control device 81 opens each valve. The control device 81 that transmits the request and receives the opening request is configured to control to open each valve.

  Hereinafter, this HEV control method will be described as functions of the control device 80 and the control device 81 with reference to the flowchart of FIG. This control method is performed while the HEV is traveling.

  First, in step S10, the control device 80 determines whether or not a condition is satisfied. This condition means that the hybrid vehicle is running in a state where the fuel injection of the engine 10 is stopped and only the motor generator 31 is driven, that is, the motor is traveling alone.

  As a situation where the condition of step S10 is satisfied, it is possible to exemplify traveling on a downhill road, an uphill road or a flat road with a gentle slope. This condition will be described more specifically. When this condition is satisfied, the situation described below occurs.

  This situation is a situation in which the target torque of the hybrid system 30 becomes equal to or less than the maximum output torque of the motor generator 31 while traveling on the travel path as described above. The control in this situation is as follows.

  First, when the accelerator pedal 95 is depressed by the driver, the control device 81 performs control to calculate a target torque based on the accelerator opening that is a detection value of the accelerator opening sensor 96. Next, the control device 80 compares the target torque with the maximum output torque of the motor generator 31, and performs control to determine whether the target torque is equal to or less than the maximum output torque. Next, when it is determined that the target torque is equal to or less than the maximum output torque, the control device 81 performs control to stop fuel injection from the injector 47. On the other hand, the control device 80 controls the motor generator 31 to transmit the driving force to the propeller shaft 22 by driving the motor generator 31. The magnitude of the output torque of the motor generator 31 is adjusted according to parameters such as the gradient of the travel path, the vehicle weight, and the travel distance.

  If it is determined in step S10 that the condition of the above situation is satisfied, the process proceeds to the next step. On the other hand, if it is determined in step S10 that the above condition is not satisfied, the control method is completed and the process returns to the start.

  Next, an opening request is transmitted from the control device 80 to the control device 81 so as to process the three controls in steps S20 to S40, and the control device 81 that has received the opening request performs the three controls in steps S20 to S40. Are processed in parallel. Steps S20 to S40 may be processed in order, but the time until the engine friction is reduced can be shortened by performing parallel processing at the same time.

  In step S20, the control device 81 opens the intake bypass valve 131. In this step S20, it is desirable that the intake bypass valve 131 is fully opened. In step S30, the control device 81 opens the exhaust bypass valve 133. In step S30, it is desirable that the exhaust bypass valve 133 is fully opened.

  In this way, by setting both the intake bypass valve 131 and the exhaust bypass valve 133 to the fully open positions, the second turbocharger 57b is bypassed, and the pump loss due to the second turbocharger 57b is reduced. This is advantageous in reducing engine friction.

  In step S40, the control device 81 opens the waste gate valve 135. In this step S40, it is desirable that the wastegate valve 135 is fully opened. Thus, by setting the wastegate valve 135 to the fully open position, the pump loss due to the first turbocharger 57a can be reduced, which is advantageous in reducing engine friction.

  When step S20 to step S40 are completed, the process returns to the start, and step S20 to step S40 are performed until the condition is not satisfied.

  By performing the control as described above, the first turbocharger 57a and the second turbocharger are running while the fuel injection of the engine 10 is stopped and only the motor generator 31 is driven. By bypassing the charger 57b and reducing the pump loss of the engine 10, the engine friction in the traveling in which the fuel injection is stopped can be reduced.

  As a result, while the fuel injection of the engine 10 is stopped and only the motor generator 31 is being driven, the flow resistance is reduced and the loss due to the engine friction is reduced. The output torque transmitted from the engine to the drive wheels can be suppressed from being reduced by the loss due to engine friction. As a result, it is possible to increase the efficiency with which the output torque generated by the motor generator 31 can be used as HEV driving force, so that fuel efficiency can be improved.

  In this embodiment, the engine 10 including the plurality of turbochargers 57a and 57b and further including the intake bypass valve 131, the exhaust bypass valve 133, and the wastegate valve 135 has been described as an example. However, in the present invention, the engine 10 may be configured by having any of those devices. Moreover, you may comprise the engine 10 having a combination of any two of those apparatuses.

  For example, an engine having only one turbocharger 57a and having a wastegate valve 135, a plurality of turbochargers 57a and 57b, and not having an intake bypass passage 130 and an intake bypass valve 131. The present invention can also be applied to an engine having an exhaust bypass path 132 and an exhaust bypass valve 133.

  In this embodiment, an example in which the control device 81 performs a control for opening the intake bypass valve 131, a control for opening the exhaust bypass valve 133, and a control for opening the wastegate valve 135 will be described. did. However, in the present invention, the control device 81 may be configured to perform any of these controls. Further, the control device 81 may be configured to perform a combination of any two of these controls.

However, when the engine 10 includes a plurality of turbochargers 57a and 57b and includes an intake bypass valve 131 and an exhaust bypass valve 133, control for opening both the intake bypass valve 131 and the exhaust bypass valve 133 is performed. It is desirable to do. In addition, when the wastegate valve 135 is provided, it is desirable to perform control to open the wastegate valve 135.

  In particular, the engine 10 is configured to include all of the intake bypass valve 131, the exhaust bypass valve 133, and the wastegate valve 135 as in this embodiment, and the control device 81 fully opens the intake bypass valve 131. It is the best mode to perform all of the control for making the exhaust bypass valve 133 fully open and the control for making the wastegate valve 135 fully open. That is, as in this embodiment, by performing all the controls, the engine friction of the engine 10 can be reduced most effectively, which is most advantageous for improving the fuel consumption.

  In this embodiment, the configuration in which the control is performed by the two controllers of the control device 80 that controls the hybrid system 30 and the control device 81 that controls the engine 10 has been described as an example, but the control is performed by one controller. Is also possible.

10 Engine 30 Hybrid system 31 Motor generator 57a, 57b Turbocharger 58a, 58b Compressor 63a, 63b Turbine 130 Intake bypass passage 131 Intake bypass valve 132 Exhaust bypass passage 133 Exhaust bypass valve 134 Wastegate passage 135 Wastegate valve 80, 81 Control device

Claims (4)

In a hybrid vehicle including a hybrid system having an engine and a motor generator, which are power sources for vehicle travel, and a control device,
An intake bypass valve that adjusts the flow rate of intake air that passes through an intake bypass passage that bypasses a compressor that is disposed in the intake passage of the engine, and an exhaust bypass passage that bypasses a turbine disposed in the exhaust passage of the engine One of the exhaust bypass valve for adjusting the flow rate of the exhaust gas passing through the engine and the waste gate valve for adjusting the flow rate of the exhaust gas flowing into the turbine disposed in the exhaust passage of the engine, or any two of them Have a combination or all,
The control device is configured to control the opening of the intake bypass valve, the control of opening the exhaust bypass valve during traveling in a state in which only the motor generator is driven while fuel injection of the engine is stopped, and The hybrid vehicle is configured to perform any one of the controls for opening the waste gate valve, a combination of any two, or all of them. The engine has a plurality of turbochargers, and supercharges only with a first turbocharger disposed downstream of the plurality of turbochargers in an exhaust passage, and the plurality of turbochargers. The intake bypass valve and the exhaust bypass for switching the multi-stage supercharging to be supercharged at,
The control device controls to fully open both the intake bypass valve and the exhaust bypass valve during traveling in a state where fuel injection of the engine is stopped and only the motor generator is driven. The hybrid vehicle according to claim 1, wherein the hybrid vehicle is configured to perform. The engine has the wastegate valve;
The control device is configured to perform control to open the wastegate valve fully open during traveling in a state where fuel injection of the engine is stopped and only the motor generator is driven. Item 3. The hybrid vehicle according to item 1 or 2. In the control method of the hybrid vehicle that stops the fuel injection of the engine and drives only the motor generator during traveling,
Opening an intake bypass valve that adjusts a flow rate of intake air that passes through an intake bypass passage that bypasses a compressor disposed in the intake passage of the engine;
Opening an exhaust bypass valve that adjusts the flow rate of exhaust gas that passes through an exhaust bypass passage that bypasses the turbine disposed in the exhaust passage of the engine;
Including a step of opening with a wastegate valve for adjusting a flow rate of exhaust gas flowing into a turbine disposed in an exhaust passage of the engine, a combination of all two, or all of them. Method for controlling a hybrid vehicle.