CN109891085B

CN109891085B - Engine starting system and engine starting device

Info

Publication number: CN109891085B
Application number: CN201780066727.1A
Authority: CN
Inventors: 竹内良友; 马场浩辅; 山本正和; 八木丰儿
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2016-10-28
Filing date: 2017-10-24
Publication date: 2021-06-25
Anticipated expiration: 2037-10-24
Also published as: JP2018071433A; DE112017005438T5; CN109891085A; WO2018079560A1; JP6624009B2

Abstract

An engine starting system (10) includes: a drive gear (23), the drive gear (23) being capable of meshing with a driven gear (92) connected to an output shaft (91) of an engine (90); a motor (21) for rotating the drive gear; an engaging device (25), the engaging device (25) changing the engaging state of the driven gear and the driving gear; a first power source (31) capable of charge and discharge; and a second power source (32) capable of charging and discharging. In an engine starting system, before a drive gear is meshed with a driven gear by a meshing device when an engine is started, electric power is supplied from a first power source to a motor and is not supplied from the first power source to the meshing device, and electric power is supplied from a second power source to the meshing device and is not supplied from the second power source to the motor.

Description

Engine starting system and engine starting device

Citation of related applications

The present application is based on Japanese patent application No. 2016-.

Technical Field

The present invention relates to an engine starting system for starting an engine.

Background

Conventionally, among the above systems, there is a system including a starter solenoid (meshing device) for moving a pinion gear in an axial direction and a starter motor (electric motor) for cranking an engine (see patent document 1). In the system described in patent document 1, switching is performed between a state in which power is supplied from the first battery to the starter solenoid and the starter motor and a state in which power is supplied from the second battery to the starter solenoid and the starter motor, based on the state of the vehicle.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-125344

Disclosure of Invention

However, when power is supplied from one power source to the starter solenoid and the starter motor, a large current may flow to the starter motor, which may cause a voltage of the power source to drop significantly. In the above case, the controllability of the electric power supplied to the starter solenoid is lowered, and there is a possibility that the engagement of the pinion gear cannot be appropriately controlled. In the system described in patent document 1, there is room for improvement in consideration of a decrease in controllability of a starter solenoid due to a current flowing to a starter motor.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an engine starting system capable of suppressing a decrease in controllability of an engagement device due to a current flowing to a motor that rotates an engine crankshaft.

A first mode for solving the above technical problem is an engine starting system comprising:

a drive gear engageable with a driven gear connected to an output shaft of an engine;

a motor that rotates the drive gear;

an engaging device that changes an engagement state between the driven gear and the driving gear;

a first power source capable of charging and discharging; and

a second power source capable of being charged and discharged,

when the engine is started, until the drive gear is meshed with the driven gear by the meshing device, electric power is supplied from the first power supply to the electric motor and is not supplied from the first power supply to the meshing device, and electric power is supplied from the second power supply to the meshing device and is not supplied from the second power supply to the electric motor.

According to the above structure. The drive gear can be engaged with a driven gear connected to an output shaft of the engine and rotated by the motor. Further, with the meshing device, the meshing state between the driven gear and the driving gear is changed. Therefore, in a state where the driven gear is meshed with the driving gear by the meshing device, the driving gear is rotated by the motor, and the engine is started.

Here, the engine starting system includes a first power source that can be charged and discharged and a second power source that can be charged and discharged. Further, at the time of starting the engine, until the engagement of the driving gear and the driven gear by the engaging device is completed, electric power is supplied from the first power source to the electric motor and electric power is not supplied from the first power source to the engaging device. Therefore, even if the voltage of the first power supply decreases due to the current flowing from the first power supply to the motor, no electric power is supplied from the first power supply to the engagement device.

On the other hand, at the time of starting the engine, until the driving gear is meshed with the driven gear by the meshing device, electric power is supplied from the second power source to the meshing device and electric power is not supplied from the second power source to the electric motor. Therefore, during the meshing process between the driving gear and the driven gear, no electric power is supplied from the second power supply to the motor, and the voltage of the second power supply does not decrease due to the flow of current to the motor. Therefore, the engagement device can be appropriately controlled by the electric power supplied from the second power source to the engagement device.

In a second aspect, power is supplied from the second power supply to the auxiliary equipment.

According to the above configuration, the auxiliary device operates using the electric power supplied from the second power supply. As described above, in the process of meshing the driving gear with the driven gear, the voltage of the second power supply does not decrease due to the flow of current to the motor. Therefore, the operation of the auxiliary equipment can be prevented from being unstable due to the current flowing to the motor.

In a third aspect, the first power source and the second power source are connected in parallel via a switch, and the switch is switched to an off state during a period until the driving gear is meshed with the driven gear by the meshing device when the engine is started.

According to the above configuration, since the first power supply and the second power supply are connected in parallel via the switch, the first power supply and the second power supply can be disconnected or connected by switching the open/closed state of the switch. Further, at the time of starting the engine, the switch is switched to the off state until the driving gear is meshed with the driven gear by the meshing device. Therefore, in the process of meshing the driving gear with the driven gear, the voltage of the second power supply does not decrease due to the flow of current to the motor, and the meshing device can be appropriately controlled. Further, the switch is switched to the closed state, so that charge and discharge can be performed between the first power supply and the second power supply.

In the fourth aspect, the switch is switched to the closed state when the start of the engine is completed.

According to the above configuration, when the start of the engine is completed, the switch is switched to the closed state. Therefore, after the start of the engine is completed, the first power supply having a reduced dischargeable capacity due to the supply of electric power to the electric motor can be charged by the second power supply. As a result, the capacity of the first power supply can be set to the minimum necessary for driving the motor, and the first power supply can be downsized.

In a fifth aspect, the engine is provided with a rotating electrical machine that generates electric power by using a driving force of the engine, and the rotating electrical machine is connected to the first power source or the second power source.

According to the above configuration, since the engine is provided with the rotating electric machine that generates electric power by the driving force of the engine, electric power can be generated by the rotating electric machine after the engine is started. Further, since the rotating electric machine is connected to the first power source or the second power source, the first power source and the second power source can be charged by the rotating electric machine after the start of the engine is completed by switching the switch to the closed state. Further, since the first power supply or the second power supply is connected to the rotating electric machine, wiring can be simplified as compared with a configuration in which the first power supply and the second power supply are connected to the rotating electric machine.

In a sixth aspect, electric power is supplied from the second power supply to auxiliary equipment, and the rotating electric machine is connected to the second power supply.

According to the above configuration, the auxiliary device operates using the electric power supplied from the second power supply. Further, the rotating electrical machine is connected to a second power source. Therefore, electric power can be supplied to the auxiliary equipment from both the second power supply and the rotating electric machine, and the operation of the auxiliary equipment can be further stabilized.

In the seventh aspect, when the start of the engine is completed, the on/off state of the switch is switched based on at least one of a charged state of the first power source and a charged state of the second power source.

According to the above configuration, when the start of the engine is completed, the on/off state of the switch is switched based on at least one of the charged state of the first power supply and the charged state of the second power supply. Therefore, the balance between the amount of charge of the first power source and the amount of charge of the second power source can be adjusted, and overdischarge and overcharge of the first power source and the second power source can be suppressed.

In an eighth aspect, a supply voltage of the first power supply is different from a supply voltage of the second power supply, and the first power supply and the second power supply are connected in parallel via a voltage conversion device.

According to the above configuration, the first power supply and the second power supply having different supply voltages are connected in parallel via the voltage conversion device. Therefore, the voltage is converted by the voltage conversion device according to the states of the first power supply and the second power supply, and electric power can be mutually supplied between the first power supply and the second power supply.

In a ninth aspect, the first power supply and the auxiliary device are connected via a first switch, the second power supply and the auxiliary device are connected via a second switch, and the first switch is switched to an open state and the second switch is switched to a closed state when an abnormality occurs in the first power supply, and the second switch is switched to an open state and the first switch is switched to a closed state when an abnormality occurs in the second power supply.

According to the above configuration, the first power supply and the auxiliary device are connected via the first switch, and the second power supply and the auxiliary device are connected via the second switch. When an abnormality occurs in the first power supply, the first switch is switched to the open state and the second switch is switched to the closed state. Therefore, even when the first power supply is abnormal, the electric power can be supplied from the second power supply to the auxiliary equipment. When an abnormality occurs in the second power supply, the second switch is switched to the open state and the first switch is switched to the closed state. Therefore, even when the second power supply is abnormal, the electric power can be supplied from the first power supply to the auxiliary equipment.

A tenth mode is an engine starting apparatus,

the method comprises the following steps: a drive gear engageable with a driven gear connected to an output shaft of an engine;

a motor that rotates the drive gear; and

an engaging device for changing an engaging state between the driven gear and the driving gear,

when the engine is started, until the drive gear is meshed with the driven gear by the meshing device, electric power is supplied from a first power supply to the electric motor and is not supplied from the first power supply to the meshing device, and electric power is supplied from a second power supply to the meshing device and is not supplied from the second power supply to the electric motor.

According to the above configuration, the engine starting apparatus is applied to the first power source and the second power source, and the engine starting system of the first embodiment can be configured, and the same operational effects as those of the first embodiment can be obtained.

In an eleventh aspect, the present invention provides a control unit that controls electric power supplied to the engagement device.

According to the above configuration, the control unit controls the electric power supplied to the engagement device. Further, in the process of meshing the driving gear with the driven gear, the voltage of the second power supply does not decrease due to the current flowing to the motor, and the meshing device can be appropriately controlled by the control unit.

In a twelfth aspect, the electric vehicle includes a motor control unit that controls a driving state of the motor.

According to the above configuration, the motor control unit can appropriately control the driving state of the motor.

Drawings

The above objects, other objects, features and advantages of the present invention will become more apparent with reference to the accompanying drawings and the following detailed description. The drawings are as follows.

Fig. 1 is a schematic diagram showing an engine starting system of a first embodiment.

Fig. 2 is a schematic diagram showing an engine starting system of a second embodiment.

Fig. 3 is a circuit diagram showing a control section of the engagement device.

Fig. 4 is a timing chart showing a relationship between the on-off state of the switch and the current.

Fig. 5 is a schematic diagram showing an engine starting system of a third embodiment.

Fig. 6 is a schematic diagram showing an engine starting system of the fourth embodiment.

Fig. 7 is a flowchart showing steps of the engine start control.

Fig. 8 is a schematic diagram showing an engine starting system of the fifth embodiment.

Fig. 9 is a flowchart showing steps of the engine start control.

Fig. 10 is a schematic diagram showing an engine starting system of a sixth embodiment.

Fig. 11 is a schematic diagram showing an engine starting system of the seventh embodiment.

Detailed Description

(first embodiment)

Hereinafter, a first embodiment embodied in an engine starting system mounted on a vehicle will be described with reference to the drawings.

As shown in fig. 1, a crankshaft 91 (corresponding to an output shaft) of the engine 90 is connected to a ring gear 92 (corresponding to a driven gear). As the engine 90, a gasoline engine, a diesel engine, or the like can be used. The operating state of the engine 90 is controlled by an ECU (Electronic Control Unit) 80. The ECU80 is configured as a microcomputer including a CPU, ROM, RAM, input/output interface, and the like.

The engine starting system 10 includes a starter 20, a first battery 31, a second battery 32, switches 35, 36, and the like. The starter 20 (corresponding to an engine starting device) includes an electric motor 21, a pinion 23, a meshing device 25, and the like.

The motor 21 is driven by the supply of the dc power, and is stopped by stopping the supply of the dc power. A pinion gear 23 is connected to the rotating shaft 22 of the motor 21. The pinion gear 23 (corresponding to a drive gear) rotates in accordance with the rotation of the rotary shaft 22 of the motor 21. The pinion 23 can mesh with the above-mentioned ring gear 92.

The engagement device 25 is a well-known device including a solenoid, a pinion moving rod, and the like. In the engagement device 25, the rotary shaft 22 of the motor 21 is moved in the axial direction toward the ring gear 92 by supplying the dc power, and the rotary shaft 22 is moved in the direction away from the ring gear 92 by stopping the supply of the dc power. That is, in the engagement device 25, the pinion 23 is engaged with the ring gear 92 by supplying the dc power, and the pinion 23 is disengaged from the ring gear 92 by releasing the engagement between the pinion 23 and the ring gear 92 by stopping the supply of the dc power.

The first battery 31 (corresponding to the first power source) and the second battery 32 (corresponding to the second power source) are batteries having the same supply voltage (for example, 12V). As the first battery 31 and the second battery 32, a lead battery, a lithium ion battery, or the like can be used. The positive electrode of the first battery 31 is connected to the motor 21 via the switch 35, and the negative electrode of the first battery 31 is grounded. The positive electrode of the second battery 32 is connected to the engaging device 25 via the switch 36, and the negative electrode of the second battery 32 is grounded. The

switches

35 and 36 are normally closed relays, for example. The first battery 31 and the second battery 32 are independent of each other and are not connected to each other.

ECU80 controls the open/close states of

switches

35 and 36 when engine 90 is started. Specifically, the ECU80 switches the switch 35 to the closed state at a predetermined timing after switching the switch 36 to the closed state. Thereby, the pinion gear 23 is meshed with the ring gear 92 and rotates. When the rotation speed of the engine 90 reaches a predetermined rotation speed, the ECU80 starts the combustion of the fuel. Then, when the rotation speed of the engine 90 reaches the crankshaft rotation end rotation speed (complete combustion speed), the ECU80 switches the

switches

35, 36 to the off state to end the start of the engine 90.

The present embodiment described in detail above has the following advantages.

The first battery 31 and the second battery 32 are independent of each other and are not connected to each other. Therefore, during the period from the start of the engine 90 to the end of cranking, electric power is supplied from the first battery 31 to the electric motor 21, and electric power is not supplied from the first battery 31 to the engagement device 25. Therefore, even if the voltage of the first battery 31 decreases due to the current flowing from the first battery 31 to the electric motor 21, no electric power is supplied from the first battery 31 to the engagement device 25.

During the period from the start of the engine 90 to the end of cranking, electric power is supplied from the second battery 32 to the engagement device 25, and electric power is not supplied from the second battery 32 to the electric motor 21. Therefore, while the pinion gear 23 is meshed with the ring gear 92, no electric power is supplied from the second battery 32 to the motor 21, and the voltage of the second battery 32 does not decrease due to the flow of current to the motor 21. Therefore, the power supplied from the second battery 32 to the engagement device 25 is set to be optimal, and the engagement device 25 can be appropriately controlled. As a result, the solenoid and the like of the engagement device 25 can be optimized, the engagement shock between the pinion gear 23 and the ring gear 92 can be reduced, and the size and durability of the engagement device 25 can be reduced.

(second embodiment)

Hereinafter, a second embodiment in which the control unit 26 is provided in place of the switch 36 of the first embodiment will be described with reference to fig. 2 to 4. Note that the same portions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 2, the starter 120 includes a control section 26. That is, the positive electrode of the second battery 32 is connected to the engagement device 25 via the control unit 26, and the negative electrode of the second battery 32 is grounded.

As shown in fig. 3, the control unit 26 includes a switch a and a switch B connected in series. As the switch A, B, a semiconductor switch or the like can be used. The input-side terminal of the switch a is connected to the positive electrode of the second battery 32. An input-side terminal of the solenoid 25a of the engagement device 25 is connected to a connection point between the output-side terminal of the switch a and the input-side terminal of the switch B. The output side terminal of the solenoid 25a is grounded. The output side terminal of the switch B is grounded. The controller 26 includes a drive circuit (not shown) for driving the switch A, B, and controls the open/close state of the switch A, B.

As shown in fig. 4, during a predetermined period TA, the control unit 26 switches the switch a to the closed state and switches the switch B to the open state. Then, during a predetermined period TB, the control unit 26 switches the switch a to the open state and switches the switch B to the closed state. In the predetermined period TB, the current flowing through the solenoid 25a flows back. Thereby, the actual current Ir flowing through the solenoid 25a is controlled to be about the required current It. In other words, the predetermined periods TA and TB are adjusted so that the actual current Ir flowing through the solenoid 25a approaches the required current It.

The present embodiment has the following advantages. Here, only the advantages different from the first embodiment will be discussed.

During the process in which the pinion gear 23 meshes with the ring gear 92, no electric power is supplied from the second battery 32 to the motor 21, and the voltage of the second battery 32 does not drop due to the flow of current to the motor 21. Therefore, the control unit 26 can appropriately control the engagement device 25 by controlling the actual current Ir (actual power) supplied to the engagement device 25 to the required current It (required power). As a result, the meshing impact between the pinion gear 23 and the ring gear 92 and the meshing sound can be reduced, and the durability of the meshing device 25 can be improved.

The above embodiment may be modified as follows.

When the engine 90 is started, the control unit 26 may control the open/close state of the switch 35 instead of controlling the open/close state of the switch 35 by the ECU 80. Specifically, the control unit 26 receives a start signal from the ECU80 to control the electric power supplied to the engagement device 25 when the engine 90 is started. Then, at the time point (for a predetermined period) when the engagement between the pinion gear 23 and the ring gear 92 is completed, the switch 35 is switched to the closed state. With the above configuration, the wiring from the ECU80 to the switch 35 can be omitted.

Further, the switch 36 of fig. 1 may be provided between the control unit 26 and the second battery 32 of fig. 2. Further, the ECU80 may switch the switch 36 to the closed state when starting the engine 90. The control unit 26 starts control of supplying electric power to the engagement device 25 by supplying electric power from the second battery 32 through the switch 36. According to the above configuration, since the switch 36 for switching between supply and interruption of electric power to the control unit 26 is provided, for example, when an abnormality occurs in the engagement device 25 or the control unit 26, these components can be disconnected from the second battery 32.

As shown by the chain line in fig. 2, the starter 120 may include a motor control unit 27 that controls the driving state of the motor 21. The controller 26 may communicate with the motor controller 27, receive a start signal from the ECU80, and transmit an operation command to the other at a predetermined timing. According to the above configuration, wiring can be simplified as compared with a configuration in which wiring is connected from the ECU80 to each of the control unit 26 and the motor control unit 27.

For example, the ECU80 switches the switch 35 to the closed state when starting the engine 90. By supplying electric power from the first battery 31 through the switch 35, the motor control unit 27 sends an engagement start command to the control unit 26 before starting driving of the electric motor 21. When the control unit 26 receives the engagement start command from the motor control unit 27, the pinion gear 23 and the ring gear 92 start to be engaged with each other by the engagement device 25. After completing the engagement, the control unit 26 sends an engagement completion signal to the motor control unit 27. Upon receiving the engagement completion signal, the motor control section 27 starts driving of the motor 21. In place of the transmission and reception of the engagement completion signal, the motor control unit 27 may start the driving of the motor 21 after a predetermined time has elapsed by using a timer or the like after transmitting the engagement start command to the control unit 26. In this case, the configuration in which the control unit 26 sends a signal to the motor control unit 27 can be omitted. Further, the switch 36 of fig. 1 may be provided between the control unit 26 and the second battery 32 of fig. 2. When receiving the start signal from the ECU80, the motor control unit 27 may switch the switch 36 to the closed state. According to the above configuration, the configuration for performing communication between the control unit 26 and the motor control unit 27 can be omitted.

Instead of the control unit 2 of fig. 2, the switch 36 of fig. 1 may be provided. Further, the motor control unit 27 may switch the switch 36 to the closed state when starting the engine 90.

In fig. 2, the starter 120 may have the motor control unit 27 and the switch 35 may be omitted. In the above case, the motor control unit 27 may receive the start signal from the ECU80 and send an engagement start command to the control unit 26 before starting the driving of the motor 21.

The control unit 26 may be provided between the starter 120 and the second battery 32.

(third embodiment)

A third embodiment in which electric power is supplied from the second battery 32 to the auxiliary equipment in the second embodiment will be described below with reference to fig. 5. The same portions as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 5,

vehicle accessories

41 and 42 are connected to the second battery 32. The

auxiliary devices

41, 42 are blowers, wipers, compressors, car navigations, radios, headlamps, etc. Further, electric power is supplied from the second battery 32 to the

auxiliary devices

41 and 42, and the

auxiliary devices

41 and 42 are operated.

The present embodiment has the following advantages. Here, only the advantages different from the second embodiment will be discussed.

The

auxiliary devices

41 and 42 are operated by the electric power supplied from the second battery 32. As described above, while the pinion gear 23 is meshed with the ring gear 92, the voltage of the second battery 32 does not decrease due to the flow of current to the motor 21. Therefore, the operation of the

auxiliaries

41 and 42 can be prevented from being unstable due to the current flowing to the motor 21.

Instead of supplying electric power from the second battery 32 to the

auxiliary devices

41 and 42, electric power may be supplied from the first battery 31 to the

auxiliary devices

41 and 42.

(fourth embodiment)

A fourth embodiment in which the first battery 31 and the second battery 32 are connected in parallel via a switch in the second embodiment will be described below with reference to fig. 6. The same portions as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 6, the positive electrode of the first battery 31 and the positive electrode of the second battery 32 are connected via a switch 37. That is, the first battery 31 and the second battery 32 are connected in parallel via the switch 37.

Fig. 7 is a flowchart showing steps of the engine start control executed by the ECU 80.

First, the ECU80 causes the control unit 26 to start the engagement of the pinion gear 23 with the ring gear 92 (S11).

Next, the ECU80 determines whether the motor 21 is rotating (S12). Specifically, whether the motor 21 is in the process of rotating is determined based on whether the switch 35 is in the closed state, whether a detection value obtained by detecting the rotation speed of the motor 21 is greater than 0, or the like. In the above determination, when it is determined that the motor 21 is rotating (S12: YES), the switch 37 is switched to the OFF state. On the other hand, when it is determined that the motor 21 is not rotating (S12: NO), the switch 37 is not switched between the open and closed states.

Subsequently, the ECU80 completes the engagement of the pinion gear 23 with the ring gear 92 by the control unit 26 (S14). In order to maintain this state even after the engagement of the pinion gear 23 with the ring gear 92 is completed, the control unit 26 causes a holding current (required current It) to flow through the solenoid 25 a. In addition, the processing of S12, S13 is continuously executed while the pinion gear 23 is meshed with the ring gear 92.

Subsequently, the ECU80 starts cranking of the engine 90 (S15). Specifically, the switch 35 is switched to the closed state in a state where the pinion 23 is meshed with the ring gear 92, so that the pinion 23 is rotated by the motor 21 (S15).

Next, the ECU80 determines whether the motor 21 is rotating (S16). In the above determination, when it is determined that the motor 21 is rotating (S16: YES), the switch 37 is switched to the OFF state (S17). On the other hand, when it is determined that the motor 21 is not rotating (S17: NO), the switch 37 is not switched between the open and closed states.

Subsequently, the ECU80 ends cranking of the engine 90 (S18). Specifically, combustion of fuel is started, and after the rotation speed of engine 90 reaches the cranking completion rotation speed, switch 35 is switched to the off state, and the supply of electric power to engagement device 25 is stopped by control unit 26. In addition, the processes of S16, S17 are continuously executed while cranking of the engine 90 is performed.

Subsequently, the ECU80 switches the switch 37 to the closed state (S19). Then, the series of processes is ended (end).

Since the first battery 31 and the second battery 32 are connected in parallel via the switch 37, the first battery 31 and the second battery 32 can be disconnected or connected by switching the open/closed state of the switch 37. When the engine 90 is started, the switch 37 is switched to the off state until the pinion 23 is meshed with the ring gear 92 by the meshing device 25. Therefore, while the pinion gear 23 is meshed with the ring gear 92, the voltage of the second battery 32 is not lowered by the current flowing to the motor 21, and the meshing device 25 can be appropriately controlled. Further, by switching the switch 37 to the closed state, charge and discharge can be performed between the first battery 31 and the second battery 32.

When the start of engine 90 is completed, switch 37 is switched to the closed state. Therefore, after the start of the engine 90 is completed, the first battery 31 having a reduced dischargeable capacity due to the supply of electric power to the electric motor 21 can be charged by the second battery 32. As a result, the capacity of the first battery 31 can be set to the minimum necessary for driving the motor 21, and the first battery 31 can be downsized.

The above embodiment may be modified as follows.

Since the required capacity of the first battery 31 (corresponding to the first power supply) can be minimized, the first power supply is not limited to a lead battery or a lithium ion battery, and a capacitor such as a lithium ion capacitor may be used.

In the process of S14, after the engagement between the pinion gear 23 and the ring gear 92 is completed, it is only necessary to maintain the engaged state, and it is not necessary to precisely control the electric power supplied to the engagement device 25. Therefore, instead of the processes at S16 and S17, the ECU80 may perform a process of increasing the electric power supplied to the engagement device 25 by the control unit 26. According to the above configuration, the meshing impact between the pinion gear 23 and the ring gear 92 and the meshing sound can be reduced, and the durability of the meshing device 25 can be improved. In a state where the engagement between the pinion gear 23 and the ring gear 92 is completed, even if the voltage of the second battery 32 is lowered due to the current flowing to the motor 21, the engaged state can be maintained.

(fifth embodiment)

A fifth embodiment in which electric power is supplied from the second battery 32 and the alternator to the

accessories

41, 42 in the fourth embodiment will be described below with reference to fig. 8. The same portions as those in the third and fourth embodiments are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 8, an alternator 95 (corresponding to a rotating electrical machine) that generates electric power using the driving force of the engine 90 is mounted on the engine 90. The alternator 95 is connected to the second battery 32 and the

accessories

41, 42. The electric power generated by the alternator 95 is supplied to the second battery 32 and the

accessories

41 and 42.

In the present embodiment, the ECU80 executes automatic stop and automatic restart of the engine 90. Specifically, the ECU80 automatically stops the engine 90 when a predetermined automatic stop condition is satisfied, and automatically restarts the engine 90 when a predetermined automatic restart condition is satisfied.

Fig. 9 is a flowchart showing steps of the engine start control executed by the ECU 80. The series of processes is started when the driver manually starts the process or when the automatic restart condition is satisfied. The processing of S11 to S18 is the same as the processing of S11 to S18 of fig. 7.

After completing cranking of engine 90 (S18), ECU80 determines whether or not the amount of charge in first battery 31 is less than the first predetermined amount (S20). The first predetermined amount is set to a minimum charge amount at which the electric motor 21 can be driven by the electric power supplied from the first battery 31 and the engine 90 can be started. In the above determination, when it is determined that the amount of charge in the first battery 31 is smaller than the first predetermined amount (yes in S20), the switch 37 is switched to the closed state (S21). On the other hand, if it is determined that the amount of charge in the first battery 31 is not less than the first predetermined amount (no in S20), the process proceeds to S22.

Next, the ECU80 determines whether the amount of charge in the first battery 31 is greater than the second predetermined amount (S22). The second predetermined amount is set to be larger than the first predetermined amount, and is set to be a charge amount that can make the charge amount of the first battery 31 sufficient. In the above determination, when it is determined that the amount of charge in the first battery 31 is larger than the second predetermined amount (yes in S22), the switch 37 is switched to the off state (S23). On the other hand, if it is determined that the amount of charge in the first battery 31 is not greater than the second predetermined amount (no in S22), the process proceeds to S24.

Next, the ECU80 determines whether or not there is a start command for the engine 90 (S24). Specifically, after the start of the engine 90 is completed (S18), the engine 90 is automatically stopped when a predetermined automatic stop condition is satisfied. Then, the ECU80 determines that there is a start instruction of the engine 90 when the predetermined automatic restart condition is satisfied, and determines that there is no start instruction of the engine 90 when the predetermined automatic restart condition is not satisfied. In the judgment process at S24, when it is judged that there is no start instruction of the engine 90 (S24: no), the process from S20 is executed again. On the other hand, in the judgment process of S24, when it is judged that there is a start instruction of the engine 90 (S24: YES), the process from S11 is executed again.

The present embodiment has the following advantages. Here, only the advantages different from the fourth embodiment will be discussed.

Since the engine 90 is provided with the alternator 95 that generates electric power by the driving force of the engine 90, electric power can be generated by the alternator 95 after the engine 90 is started. Since the alternator 95 is connected to the second battery 32, the first battery 31 and the second battery 32 can be charged by the alternator 95 after the start of the engine 90 is completed by switching the switch 37 to the closed state,

since the second battery 32 is connected to the alternator 95 and the first battery 31 is not connected to the alternator 95, wiring can be simplified as compared with a configuration in which the first battery 31 and the second battery 32 are connected to the alternator 95.

The alternator 95 is connected to the second battery 32. Therefore, electric power can be supplied to the

auxiliaries

41 and 42 from both the second battery 32 and the alternator 95, and the operations of the

auxiliaries

41 and 42 can be further stabilized.

When the start of the engine 90 is completed, the open/close state of the switch 37 is switched based on the state of charge of the first battery 31. Therefore, the balance between the amount of charge of the first battery 31 and the amount of charge of the second battery 32 can be adjusted, and overdischarge and overcharge of the first battery 31 and the second battery 32 can be suppressed.

When it is determined that the amount of charge in the first battery 31 is smaller than the first predetermined amount, the switch 37 is switched to the closed state. Therefore, the charge amount of the first battery 31 can be increased to the minimum charge amount at which the engine 90 can be started or more.

When it is determined that the amount of charge in the first battery 31 is larger than the second predetermined amount, the switch 37 is switched to the off state. Therefore, when the amount of charge of the first battery 31 becomes sufficient, the charging of the first battery 31 can be completed.

The above embodiment may be modified as follows.

The first battery 31 may be connected to the alternator 95, and the second battery 32 may not be connected to the alternator 95. In this case, the wiring can be simplified as compared with the configuration in which the first battery 31 and the second battery 32 are connected to the alternator 95.

When the start of engine 90 is completed, ECU80 may switch the open/close state of switch 37 based on the state of charge of second battery 32. In the above case, too, the balance between the amount of charge of the first battery 31 and the amount of charge of the second battery 32 can be adjusted, and overdischarge and overcharge of the first battery 31 and the second battery 32 can be suppressed.

Instead of the alternator 95, a Motor Generator (MG) capable of performing power running and power generation may be used. In the above case, when the engine 90 is automatically restarted, the engine 90 can be started by the MG.

(sixth embodiment)

A sixth embodiment in which the first battery 31 is a battery having a higher supply voltage than the second battery 32 and a power conversion device is provided in place of the switch 37 in the fifth embodiment will be described below with reference to fig. 10. The same portions as those in the fifth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 10, the supply voltage of first battery 131 is higher than the supply voltage of second battery 32. For example, the supply voltage of the first battery 131 is 48V.

The first battery 131 and the second battery 32 are connected in parallel via the voltage conversion device 51. The voltage conversion device 51 has a function of stepping down the voltage input from the first battery 131 to output to the second battery 32 and a function of stepping up the voltage input from the second battery 32 to output to the first battery 131. The voltage conversion device 51 has a function of disconnecting the first battery 131 and the second battery 32.

The present embodiment has the following advantages. Here, only the advantages different from the fifth embodiment will be discussed.

In the process of meshing the pinion gear 23 with the ring gear 92, the connection between the first battery 131 and the second battery 32 is cut off by the voltage conversion device 51, so that the voltage of the second battery 32 is not lowered by the flow of current to the motor 21, and the meshing device 25 can be appropriately controlled.

The first battery 131 and the second battery 32 having different supply voltages are connected in parallel via the voltage conversion device 51. Therefore, the voltage is converted by the voltage conversion device 51 according to the states of the first battery 131 and the second battery 32, and electric power can be mutually supplied between the first battery 131 and the second battery 32.

When electric power cannot be supplied from the first battery 131, as a process in an emergency, the voltage converter 51 can boost the voltage input from the second battery 32 and output the boosted voltage to the electric motor 21. This can prevent the engine 90 from being unable to start. As a case where electric power cannot be supplied from the first battery 131, for example, a case where the amount of charge of the first battery 131 is insufficient may be assumed.

When electric power cannot be supplied from the second battery 32, the voltage input from the first battery 131 may be stepped down by the voltage conversion device 51 and output to the control unit 26 as an emergency process. This can prevent the engine 90 from being unable to start. Further, the voltage input from the first battery 131 is stepped down by the voltage conversion device 51 to be output to the

auxiliary devices

41 and 42, so that the operations of the

auxiliary devices

41 and 42 can be continued.

The above embodiment may be modified as follows.

The second battery 32 may be a battery having a higher supply voltage than the first battery 131. In the above case, the voltage increase and decrease by the voltage conversion device 51 are in opposite directions.

The voltage conversion device 51 may be configured to perform only one of voltage increase and voltage decrease. In the above case, by reducing the functions of the voltage conversion device 51, the voltage conversion device 51 can be downsized and can be manufactured at low cost.

(seventh embodiment)

A seventh embodiment in which the second battery 32 and the

accessories

41 and 42 are connected via switches in the fifth embodiment will be described below with reference to fig. 11. The same portions as those in the fifth embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 11, the first battery 31 and the

auxiliary devices

41 and 42 are connected via a switch 37 (corresponding to a first switch). The second battery 32 and the

auxiliary devices

41 and 42 are connected via a switch 38 (corresponding to a second switch). The alternator 95 is connected to the connection point between the

switches

37, 38 and the

auxiliary devices

41, 42.

When an abnormality occurs in the first battery 31, the ECU80 switches the switch 37 to the open state and switches the switch 38 to the closed state. When an abnormality occurs in the second battery 32, the ECU80 switches the switch 38 to the open state and switches the switch 37 to the closed state. As a case where an abnormality occurs in the first battery 31, for example, it is assumed that a short circuit occurs in the first battery 31.

When an abnormality occurs in the first battery 31, the switch 37 is switched to the open state and the switch 38 is switched to the closed state. Therefore, even when an abnormality occurs in the first battery 31, electric power can be supplied from the second battery 32 to the

auxiliary devices

41 and 42. When an abnormality occurs in the second battery 32, the switch 38 is switched to the open state and the switch 37 is switched to the closed state. Therefore, even when an abnormality occurs in the second battery 32, electric power can be supplied from the first battery 31 to the

auxiliary machines

41 and 42. As a result, the operation of the

auxiliary devices

41 and 42 can be continued.

Although the present invention has been described in terms of embodiments, it should be understood that the present invention is not limited to the embodiments and configurations described above. The present invention also includes various modifications and modifications within an equivalent range. In addition, various combinations and modes, and other combinations and modes including only one element, one or more elements, and one or less elements also belong to the scope and the idea of the present invention.

Claims

1. An engine starting system (10), comprising:

a drive gear (23), the drive gear (23) being capable of meshing with a driven gear (92) connected to an output shaft (91) of an engine (90);

a motor (21), the motor (21) rotating the drive gear;

an engaging device (25), the engaging device (25) changing an engaging state of the driven gear and the driving gear;

a first power source (31, 131) capable of charge and discharge; and

a second power source (32) capable of charging and discharging,

the first power supply and the second power supply are connected in parallel via a switch (37),

at the time of starting the engine, before the drive gear is meshed with the driven gear by the meshing device, the switch is switched to an off state, electric power is supplied from the first power supply to the motor and electric power is not supplied from the first power supply to the meshing device, electric power is supplied from the second power supply to the meshing device and electric power is not supplied from the second power supply to the motor,

when the start of the engine is completed, the on/off state of the switch is switched based on at least one of the state of charge of the first power supply and the state of charge of the second power supply.

2. The engine starting system of claim 1,

electric power is supplied from the second power supply to the auxiliary devices (41, 42).

3. The engine starting system as claimed in claim 1 or 2,

the engine is provided with a rotating electric machine (95) which generates electricity by using the driving force of the engine,

the rotating electric machine is connected to the first power source or the second power source.

4. An engine starting system as set forth in claim 3,

supplying power from the second power source to the auxiliary device,

the rotating motor is connected with the second power supply.