JP5311647B2 - Internal combustion engine starting device - Google Patents

Description

  The present invention relates to an internal combustion engine starter that starts an internal combustion engine.

  In a conventional vehicle (for example, a gasoline vehicle), an internal combustion engine is started using a starter motor. In this vehicle, when an ignition key is inserted into the vehicle and turned, a contact is made, the starter motor starts rotating, and the internal combustion engine is started simultaneously with the start of rotation of the starter motor.

  In other conventional vehicles (for example, hybrid vehicles), an internal combustion engine is started using a high-pressure motor. In this vehicle, the target rotational speed of the high-pressure motor is determined according to the coolant temperature and intake air temperature of the internal combustion engine, and the internal combustion engine is started according to the target rotational speed or the target negative pressure (for example, Patent Document 1). Therefore, since the fuel injection is performed using the negative pressure by increasing the rotation speed of the internal combustion engine, the fuel consumption can be reduced.

JP 2000-186654 A

  However, in a vehicle that starts an internal combustion engine using a conventional starter motor, the starter motor is not controlled at all. Therefore, when fuel injection is started simultaneously with the start of rotation of the starter motor, the fuel is reliably burned in the internal combustion engine. As described above, the fuel consumption is increased because more fuel is used than during normal operation.

  In addition, in a vehicle that starts an internal combustion engine using a conventional high-voltage motor, the temperature of the capacitor that supplies power to the high-voltage motor is referenced, but it depends on the state of charge (SOC) and voltage of the capacitor. Therefore, an expensive inverter using a switching element is required in order to output a constant torque. On the other hand, when this expensive inverter is not used, for example, a brush motor or a motor that does not require an inverter is used, the rotational speed increase degree and the reachable rotational speed differ depending on the voltage applied to the high-voltage motor. That is, a desired torque output cannot be performed, and the rotational speed of the motor varies.

  The present invention has been made in view of the above circumstances, and provides an internal combustion engine starter that can achieve both reliable start of an internal combustion engine and reduction of fuel consumption even when an inverter is not used. Objective.

In order to solve the above problems and achieve the object, the internal combustion engine starter according to the first aspect of the present invention starts an internal combustion engine (for example, the internal combustion engine 10 in the embodiment) and can be driven without an inverter. A starting device including an electric motor (for example, the electric motor 20 in the embodiment) and a capacitor for supplying electric power to the electric motor (for example, the capacitor 30 in the embodiment), the temperature of the motor, the temperature of the capacitor, And a state detection unit (for example, voltage detection unit 30v in the embodiment) for detecting the voltage of the battery, and the electric motor when the electric motor starts the internal combustion engine based on each detection result of the state detection unit A target rotational speed deriving unit (for example, the ECU 40 in the embodiment) for deriving the target rotational speed of the motor, and an actual rotational speed detecting unit (for example, the rotational speed detecting unit 2 in the embodiment) for detecting the actual rotational speed of the motor. r) and fuel injection that permits fuel injection to the internal combustion engine after the actual rotational speed detected by the actual rotational speed detection unit reaches the target rotational speed derived by the target rotational speed deriving unit A control unit (e.g., ECU 40 in the embodiment), and the target rotation speed deriving unit is based on each of the temperature of the electric motor, the temperature of the capacitor, and the voltage of the capacitor detected by the state detection unit. Te, and candidate derive the target rotational speed of the electric motor, respectively, among the three candidates, characterized that you select the lowest value candidate as an official target speed.

Furthermore, the internal combustion engine starter according to a second aspect of the invention is characterized in that the internal combustion engine starter is mounted on a vehicle that travels by power from at least one of the electric motor and the internal combustion engine.

According to the internal combustion engine starting device of the first aspect of the present invention, it is possible to achieve both reliable start of the internal combustion engine and reduction of fuel consumption even when the inverter is not used. Further, by selecting the lowest candidate among the plurality of target rotational speed candidates as the official target rotational speed, it is possible to further reduce fuel consumption. Furthermore, an optimal target rotational speed can be selected by detecting a state value that affects the actual rotational speed of the electric motor.

According to the internal combustion engine starting device of the invention described in claim 2, the vehicle in which the internal combustion engine starting device mounted thereon, without using an expensive inverter, it is possible to realize the starting of reliable engine, fuel consumption Reduction can be realized.

The block diagram which shows an example of the main structures of the vehicle in embodiment of this invention The figure which shows an example of the circuit structure of the electric motor in embodiment of this invention The flowchart which shows an example of operation | movement when ECU in embodiment of this invention derives | leads-out rotation speed using the voltage of a capacitor | condenser. The figure which shows an example of the relationship between the voltage of a capacitor | condenser in embodiment of this invention, and target rotation speed The flowchart which shows an example of operation | movement when ECU in embodiment of this invention derives | leads-out rotation speed using the temperature of an electrical storage device. The flowchart which shows an example of operation | movement when ECU in embodiment of this invention derives target rotation speed using the temperature of an electric motor. The flowchart in an embodiment of the present invention shows an example of an operation when the target rotational speed is derived using the state value of the starting device including the electric motor and the capacitor. The flowchart which shows an example of operation | movement when ECU in embodiment of this invention starts an internal combustion engine. The figure which shows an example of the state transition of the fuel-injection state to the internal combustion engine in embodiment of this invention, the drive state of an electric motor, and the actual rotational speed of an electric motor

  An internal combustion engine starter according to an embodiment of the present invention will be described below with reference to the drawings.

  The vehicle of this embodiment is a HEV (Hybrid Electrical Vehicle), that is, a hybrid vehicle, and the vehicle travels by the driving force of an electric motor and / or an internal combustion engine. Hereinafter, it is assumed that the drive shaft of an electric motor (for example, a generator motor) is not directly connected to the drive shaft of the internal combustion engine, but the same effect can be obtained even in a directly connected state.

  FIG. 1 is a block diagram illustrating an example of a main configuration of a vehicle according to an embodiment of the present invention. A vehicle 1 shown in FIG. 1 includes an internal combustion engine (engine) 10, an electric motor (motor) 20, a capacitor (battery) 30, and an ECU (Electric Control Unit) 40. Part or the whole of the vehicle 1 has a function as an internal combustion engine starting device.

  The internal combustion engine 10 operates as a prime mover, and generates power (torque) by burning fuel injected and supplied from an injector in accordance with a fuel injection command and an ignition command from the ECU 40. Further, the coolant temperature of the internal combustion engine 10 is detected by a water temperature detector (not shown). Further, the rotational speed of the internal combustion engine 10 is detected by a rotational speed detector (not shown).

  The electric motor 20 is a generator motor, for example, and starts the internal combustion engine 10. Details of the internal configuration of the electric motor 20 will be described later. Further, the electric motor 20 is driven based on the torque command value from the ECU 40, so that the vehicle 1 performs electric running. Further, power is transmitted between the internal combustion engine 10 and the generator 20 by belt transmission. The second temperature detector 20t detects the temperature of the electric motor 20. Further, the rotational speed detection unit 20r detects the actual rotational speed (actual rotational speed) of the electric motor 20.

  The storage battery 30 has a plurality of storage cells connected in series and is a high voltage battery that supplies a high voltage of, for example, 100 to 200 V, and is mounted with a storage battery such as a lithium ion battery. In addition, the battery 30 supplies power to the electric motor 20. In addition, the first temperature detection unit 30 t detects the temperature of the battery 30. In addition, the voltage detection unit 30v detects the voltage across the terminals of the battery 30.

  The ECU 40 is at least one of the temperature of the electric motor 20 detected by the second temperature detector 20t, the temperature of the capacitor 30 detected by the first temperature detector 30t, and the voltage of the capacitor 30 detected by the voltage detector 30v. Based on the above, the target rotational speed of the electric motor 20 when the electric motor 20 starts the internal combustion engine 10 is derived. Here, “deriving” means that a map in which a target rotational speed is uniquely determined from at least one of the temperature and voltage is prepared in advance in a storage unit (not shown), and the target rotational speed is determined by referring to the map. Both obtaining and calculating the target rotational speed from at least one of the temperature and voltage. Further, the ECU 40 permits fuel injection and ignition from the injector to the internal combustion engine 10 after the actual rotational speed detected by the rotational speed detection unit 20r reaches the derived target rotational speed.

  Further, the ECU 40 controls the internal combustion engine 10 by sending a fuel injection command and an ignition command to the internal combustion engine 10 according to information on the rotational speed of the internal combustion engine 10 and the coolant temperature from the internal combustion engine 10. Further, the ECU 40 torques the electric motor 20 based on the actual rotational speed of the electric motor 10 from the electric motor 20, the torque execution value, the temperature information of the electric motor 20, and the voltage and temperature information of the electric accumulator 30 from the electric accumulator 30. A command value is sent and the drive control of the electric motor 20 is performed.

Next, details of the configuration of the electric motor 20 will be described.
The electric motor 20 is an electric motor that does not require an inverter, for example, a generator motor by phase switching. FIG. 2 is a diagram illustrating an example of a circuit configuration of the electric motor 20.

  The electric motor 20 shown in FIG. 2 is a three-phase (U-phase, V-phase, W-phase) DC motor, and a phase switching control unit (not shown) determines the rotation angle of the electric motor 20 detected by a rotation angle detection unit (not shown). Accordingly, on / off of the switch group 21 (semiconductor switch group) is controlled so that current flows only in the energized phase. In this electric motor 20, according to Ohm's law, the current flowing through each phase is determined according to the voltage of the capacitor 30 that is the supply voltage to the electric motor 20. Further, the torque output generated by the electric motor 20 is determined by the magnitude of the current, and the actual rotational speed of the electric motor 20 is determined by the torque output.

  Therefore, when the voltage of the battery 30 changes, the actual rotational speed of the electric motor 20 also inevitably changes. Further, when the temperature of the battery 30 changes, the internal resistance value of the battery 30 changes and the output voltage of the battery 30 changes, so the actual rotational speed of the electric motor 20 also inevitably changes. Further, when the temperature of the electric motor 20 is not constant, the resistance value of the load resistance unit 22 of the electric motor 20 changes, so that the current flowing through each phase changes, and the actual rotational speed of the electric motor 20 also inevitably changes.

  As described above, in the vehicle 1 of the present embodiment, the actual rotational speed of the electric motor 20 changes according to the state of the electric motor 20 and the battery 30, but the ECU 40 of the present embodiment derives the target rotational speed and the internal combustion engine. By performing this starting control, it is possible to set an appropriate target rotational speed without providing an expensive inverter, and to reliably start the internal combustion engine 10 and reduce fuel consumption.

Next, the operation when the ECU 40 derives the target rotation speed will be described.
FIG. 3 is a flowchart showing an example of the operation when the ECU 40 derives the target rotation speed using the voltage of the battery 30. In the process of FIG. 3, the ECU 40 searches for a target rotational speed from a predetermined map based on the voltage of the battery 30 (step S11). Here, the predetermined map includes information (for example, information corresponding to one to one) in which the target rotational speed is uniquely determined from the voltage of the battery 30. In the map, the target rotational speed is described so as to be between a predetermined target upper limit value and a predetermined target lower limit value (see FIG. 9). Note that the ECU 40 may obtain the target rotational speed by calculation based on the voltage of the battery 30. With the processing in FIG. 3, it is possible to set an appropriate target rotational speed of the electric motor 20 according to the state (voltage) of the battery 30.

  Here, FIG. 4 is a diagram illustrating an example of the relationship between the voltage of the battery 30 and the target rotational speed. The voltage 0 to v1 is constant at a low target speed r1, but the target speed increases as the voltage increases between voltages v1 and v2, and becomes constant at a high target speed r2 when the voltage exceeds v2. . Thus, an appropriate target rotation speed can be set according to the voltage value.

  FIG. 5 is a flowchart illustrating an example of an operation when the ECU 40 derives the target rotation speed using the temperature of the battery 30. In the process of FIG. 5, the ECU 40 searches for a target rotational speed from a predetermined map based on the temperature of the battery 30 (step S21). Here, the predetermined map includes information (for example, information corresponding to one to one) in which the target rotational speed is uniquely determined from the temperature of the battery 30. In the map, the target rotational speed is described so as to be between a predetermined target upper limit value and a predetermined target lower limit value (see FIG. 9). Note that the ECU 40 may obtain the target rotational speed by calculation based on the temperature of the battery 30. With the processing in FIG. 5, it is possible to set an appropriate target rotational speed of the electric motor 20 according to the state (temperature) of the battery 30.

  FIG. 6 is a flowchart illustrating an example of an operation when the ECU 40 derives the target rotation speed using the temperature of the electric motor 20. In the process of FIG. 6, the ECU 40 searches for a target rotational speed from a predetermined map based on the temperature of the electric motor 20 (step S31). Here, the predetermined map includes information (for example, information corresponding to one to one) in which the target rotational speed is uniquely determined from the temperature of the electric motor 20. In the map, the target rotational speed is described so as to be between a predetermined target upper limit value and a predetermined target lower limit value (see FIG. 9). Note that the ECU 40 may obtain the target rotational speed by calculation based on the temperature of the electric motor 20. With the processing in FIG. 6, it is possible to set an appropriate target rotational speed of the electric motor 20 according to the state (temperature) of the electric motor 20.

  FIG. 7 is a flowchart illustrating an example of an operation when the ECU 40 derives the target rotational speed using the state values of the starting device including the electric motor 20 and the battery 30. In the process of FIG. 7, first, similarly to steps S <b> 11, 21, and 31, the target rotational speed corresponding to the voltage of the battery 30, the target rotational speed corresponding to the temperature of the battery 30, and the target rotational speed corresponding to the temperature of the electric motor 20 are obtained. By searching, these target rotational speeds are set as candidates for formal target rotational speeds. Subsequently, the ECU 40 selects a candidate having the lowest rotational speed among these candidates as the official target rotational speed (step S41). As described above, when a plurality of state values (that is, state values indicating one state of the starting device including the electric motor 20 and the capacitor 30) related to the voltage and temperature detected by each detection unit are included, the ECU 40 has a plurality of states. Based on each of the values, the target rotational speed of the electric motor 20 is derived and set as candidates, and the candidate having the lowest target rotational speed of the electric motor 20 is selected as the official target rotational speed from among these candidates. Furthermore, fuel consumption can be reduced.

Next, the operation when the ECU 40 starts the internal combustion engine 10 will be described.
FIG. 8 is a flowchart showing an example of the operation when the ECU 40 starts the internal combustion engine 10.

  First, as an initial state, the ECU 40 prohibits fuel injection from the injector to the internal combustion engine 10 (step S51). Subsequently, the ECU 40 determines whether or not the actual rotational speed detected by the rotational speed detection unit 20r is equal to or higher than the target rotational speed derived by any of the methods shown in FIGS. Step S52). When the actual rotational speed is equal to or higher than the target rotational speed, the ECU 40 permits fuel injection to the internal combustion engine 10 (step S53). On the other hand, when the actual rotational speed is less than the target rotational speed, the process of step S52 is repeated until the actual rotational speed becomes equal to or higher than the target rotational speed.

  According to the process of FIG. 8, since fuel injection is prohibited until the actual rotational speed of the electric motor 20 reaches the target rotational speed, a large amount of fuel is kept in a state where the actual rotational speed is low in order to reliably start the internal combustion engine 10. Injecting can be avoided.

Next, the state transition of the fuel injection state to the internal combustion engine 10, the driving state of the electric motor 20, and the rotational speed of the electric motor 20 will be described.
FIG. 9 is a diagram illustrating an example of a state transition of a fuel injection state to the internal combustion engine 10, a driving state of the electric motor 20, and a rotation speed of the electric motor 20.

  First, at time t1, the ECU 40 controls the electric motor 20 to start driving. The rotation speed of the electric motor 20 increases by starting driving. Similarly, the rotational speed of the internal combustion engine 10 to which power is transmitted increases.

  Subsequently, at time t <b> 2, the ECU 40 permits fuel injection from the injector to the internal combustion engine 10 when the actual rotational speed of the electric motor 20 reaches the target rotational speed. Thus, instead of increasing the rotational speed of the internal combustion engine 10 by combustion of the supplied fuel, by starting the fuel injection after increasing the actual rotational speed of the electric motor 20 to the target rotational speed, the fuel injection of FIG. It is possible to reduce fuel consumption in the hatched portion L1.

  Subsequently, at time t3, the ECU 40 controls to stop driving the electric motor 20 when the actual rotational speed of the electric motor 20 reaches a complete starting rotational speed at which the internal combustion engine is completely started. The complete starting rotational speed is larger than the target upper limit value.

  According to such an internal combustion engine starting device for starting the internal combustion engine 10 of the vehicle 1, it is possible to reliably start the internal combustion engine 10 and reduce fuel consumption without providing an expensive inverter.

  Further, even if the vehicle form described above is different from the vehicle form, it can be applied as long as the vehicle can obtain the same effect as the internal combustion engine starting device of the present embodiment.

  INDUSTRIAL APPLICABILITY The present invention is useful for an internal combustion engine starter that can achieve both reliable start of an internal combustion engine and reduction of fuel consumption even when an inverter is not used.

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Internal combustion engine 20 Electric motor 20t 2nd temperature detection part 20r Rotational speed detection part 30 Capacitor 20t 1st temperature detection part 20v Voltage detection part 40 ECU

Claims (2)

A starting device that starts an internal combustion engine and includes an electric motor that can be driven without an inverter; and a capacitor that supplies electric power to the electric motor;
A state detector for detecting the temperature of the motor, the temperature of the capacitor, and the voltage of the capacitor ;
A target rotational speed deriving unit for deriving a target rotational speed of the electric motor when the electric motor starts the internal combustion engine based on each detection result of the state detecting unit;
An actual rotational speed detection unit for detecting the actual rotational speed of the electric motor;
A fuel injection control unit that permits fuel injection to the internal combustion engine after the actual rotational speed detected by the actual rotational speed detection unit reaches the target rotational speed derived by the target rotational speed deriving unit; equipped with a,
The target rotational speed deriving unit derives the target rotational speed of the electric motor as a candidate based on each of the temperature of the electric motor, the temperature of the electric storage device, and the voltage of the electric storage device detected by the state detection unit, of the three candidates, the internal combustion engine starting device that select the value is the lowest candidate as an official target speed. An internal combustion engine starting device according to claim 1 ,
The internal combustion engine starter is an internal combustion engine starter that is mounted on a vehicle that is driven by power from at least one of the electric motor and the internal combustion engine.

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