Hybrid vehicle

Abstract

To provide a hybrid vehicle which can reduce the load of a clutch in consideration of amount of charge of a battery.SOLUTION: A hybrid vehicle comprises: an engine which can transfer power through a clutch to a drive wheel; a motor generator which can transfer power without passing through the clutch to the drive wheel; a high-voltage battery which supplies the motor generator with electric power; and a controller which makes, when amount of charge of the high-voltage battery is a prescribed amount Cth of charge or more and temperature of the clutch is a prescribed temperature Ton or more, the clutch be in a cut-off state so that power of the motor generator is transferred to the drive wheel to start the vehicle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to hybrid vehicles. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle that monitors whether or not there are any abnormalities, such as slippage or overheating, of the clutch in an engaged state, and if an abnormality is detected, forces the vehicle into a series hybrid driving mode in which the clutch is disengaged and the motor mechanically drives or brakes the wheels, thereby preventing a deterioration in driving characteristics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-332009 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the hybrid vehicle described in Patent Document 1, the charge level of the storage battery that supplies power to the motor that drives the wheels is not taken into consideration. Therefore, if the charge level is low or if it is difficult to supply power from the storage battery to the motor, there is a risk that the vehicle will not be able to drive in series hybrid mode even if a clutch abnormality is detected.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a hybrid vehicle that can reduce the load on the clutch by taking into account the charge level of the battery. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention comprises an engine capable of transmitting power to the drive wheels via a clutch, a motor capable of transmitting power to the drive wheels without using the clutch, a battery that supplies power to the motor, and a control device that, when the charge level of the battery is equal to or greater than a predetermined charge level and the temperature of the clutch is equal to or greater than a predetermined temperature, disengages the clutch and transmits the power of the motor to the drive wheels to start the vehicle. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a hybrid vehicle that can reduce the load on the clutch by taking into account the charge level of the battery. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of a control device for a hybrid vehicle according to an embodiment of the present invention. [Figure 3] FIG. 3 is a flowchart showing a process flow of the running mode switching control at the time of starting, which is executed by the control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 4] FIG. 4 is a time chart showing an example of a change from a state in which the battery charge amount is low in a hybrid vehicle according to an embodiment of the present invention. [Figure 5] FIG. 5 is a time chart showing an example of a change from a state in which the battery is highly charged in a hybrid vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A hybrid vehicle according to one embodiment of the present invention includes an engine capable of transmitting power to drive wheels via a clutch, a motor capable of transmitting power to the drive wheels without using a clutch, a battery that supplies power to the motor, and a control device that disengages the clutch and transmits power from the motor to the drive wheels to start the vehicle when the battery is charged to a predetermined level or more and the clutch temperature is equal to or higher than a predetermined temperature. This allows the hybrid vehicle according to one embodiment of the present invention to reduce the load on the clutch in consideration of the charge level of the battery. [Example]

[0010] A hybrid vehicle according to an embodiment of the present invention will be described below with reference to FIGS.

[0011] As shown in Fig. 1, the hybrid vehicle 1 includes an internal combustion engine 2, a transmission 3, a motor generator (indicated as "MG" in Fig. 1) 4 as a motor, and drive wheels 5. The engine 2 and the motor generator 4 function as a power source that generates power (torque) for driving the hybrid vehicle 1.

[0012] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes for each cylinder, including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The engine 2 is configured to be able to transmit power to the drive wheels 5 via a clutch 32, which will be described later.

[0013] An ISG (Integrated Starter Generator) 20 and a starter (indicated as "ST" in FIG. 1) 21 are connected to the engine 2. The ISG 20 is connected to a crankshaft 18 of the engine 2 via a power transmission member such as a belt 22. The ISG 20 functions as an electric motor that rotates when supplied with electric power, thereby driving the engine 2 to rotate, and also functions as a generator that converts the rotational force input from the crankshaft 18 into electric power.

[0014] In this embodiment, the ISG 20 functions as an electric motor to restart the engine 2 from a stopped state caused by the idling stop function. The ISG 20 also functions as an electric motor to assist the running of the hybrid vehicle 1.

[0015] The starter 21 includes a motor and a pinion gear (not shown). The starter 21 rotates the motor to rotate the crankshaft 18, thereby providing the rotational force for starting the engine 2. In this manner, the engine 2 is started by the starter 21 and is restarted by the ISG 20 from a stopped state due to the idling stop function.

[0016] The transmission 3 changes the speed of the rotation output from the engine 2 and drives the drive wheels 5 via the drive shaft 23. The transmission 3 includes a speed change mechanism 31, a clutch 32, and an actuator (not shown).

[0017] The transmission 3 is configured as an AMT (Automated Manual Transmission), which is an automatic transmission that automates the gear shifting operation based on the structure of a manual transmission, and an actuator is used to change gears in the transmission mechanism 31 and to engage and disengage the clutch 32.

[0018] The clutch 32 is a friction clutch that can be switched between a connected state in which the power transmission path between the engine 2 and the transmission mechanism 31 is connected and a disconnected state in which the power transmission path is disconnected by a clutch actuator 14 (see FIG. 2) described later.

[0019] The motor generator 4 is connected to the output side of the transmission mechanism 31 via a power transmission mechanism 42 such as a chain. Therefore, no disconnection mechanism such as the clutch 32 is provided between the motor generator 4 and the drive wheels 5, and the motor generator 4 is directly connected to the drive wheels 5 via the power transmission mechanism 42. As a result, the motor generator 4 is configured to be able to transmit power to the drive wheels 5 without using the clutch 32.

[0020] The motor generator 4 functions as an electric motor and also functions as a generator, and is capable of generating electricity when the hybrid vehicle 1 runs.

[0021] In this way, the hybrid vehicle 1 forms a parallel hybrid system that can use the power of both the engine 2 and the motor generator 4 to drive the vehicle, and is a hybrid vehicle that runs on the power output by at least one of the engine 2 and the motor generator 4.

[0022] The hybrid vehicle 1 is equipped with a high-voltage battery (indicated as "HV BT" in FIG. 1) 40 as a battery, and a low-voltage battery (indicated as "Pb BT" in FIG. 1) 50. The high-voltage battery 40 and the low-voltage battery 50 are each composed of a rechargeable secondary battery.

[0023] The high-voltage battery 40 is made up of, for example, a lithium-ion battery, and is electrically connected to the motor generator 4 via an inverter (indicated as "INV" in FIG. 1) 41, and is configured to be able to supply electric power to the motor generator 4.

[0024] The inverter 41 is configured to convert AC power to DC power and vice versa, and when powering the motor generator 4, for example, it converts the DC power discharged from the high-voltage battery 40 into AC power and supplies it to the motor generator 4. On the other hand, when powering the motor generator 4, the inverter 41 converts the AC power generated by the motor generator 4 into DC power and charges the high-voltage battery 40.

[0025] The low-voltage battery 50 is, for example, a lead battery, and is electrically connected to the ISG 20 and the starter 21, and is configured to be able to supply power to the ISG 20 and the starter 21. The low-voltage battery 50 is also configured to be able to supply power to electrical loads other than the ISG 20 and the starter 21.

[0026] 2, the hybrid vehicle 1 includes a control device 10. The control device 10 is configured by a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, etc., an input port, and an output port.

[0027] The ROM of these computer units stores programs for causing the computer units to function as the control device 10, together with various constants and maps, for example.

[0028] The control device 10 is connected to various sensors such as a crank angle sensor 11, a vehicle speed sensor 12, a clutch temperature sensor 13, and the like.

[0029] The crank angle sensor 11 detects the rotation angle (hereinafter referred to as "crank angle") of the crankshaft 18 of the engine 2. The control device 10 calculates the engine speed, which is the rotation speed of the engine 2, based on information indicating the crank angle input from the crank angle sensor 11.

[0030] The vehicle speed sensor 12 detects the vehicle speed, which is the speed of the hybrid vehicle 1. The clutch temperature sensor 13 detects the temperature of the clutch 32 (hereinafter referred to as "clutch temperature"), i.e., the temperature of the friction surface of the clutch 32. The clutch temperature may be estimated by the control device 10 based on, for example, the engine speed, the input side speed of the transmission mechanism 31, the slip amount of the clutch 32, the heat capacity or absorbed energy of the clutch 32, etc.

[0031] The control device 10 is also connected to various devices such as the motor generator 4 and the clutch actuator 14. The clutch actuator 14 switches the operating state of the clutch 32.

[0032] Furthermore, various controllers such as an engine ECU 15 and a battery management controller 16 are connected to the control device 10 so as to be able to communicate bidirectionally. The engine ECU 15 controls the operation of the engine 2 by controlling an ignition device and a fuel injection device (not shown).

[0033] The battery management controller 16 is configured to manage the state of the high-voltage battery 40, such as the charge amount. The battery management controller 16 monitors the charge amount of the high-voltage battery 40 and transmits, for example, the current charge amount to the control device 10.

[0034] The control device 10 is configured to switch the running state (running mode) of the hybrid vehicle 1. The running states of the hybrid vehicle 1 include EV running, E / G running, and HEV running.

[0035] EV driving is a driving state in which the operation of the engine 2 is stopped and the hybrid vehicle 1 is driven by the power (hereinafter also referred to as motor torque) of the motor generator 4. At this time, the clutch 32 is switched by the clutch actuator 14 to a disconnected state in which the power transmission path between the engine 2 and the transmission mechanism 31 is disconnected. During EV driving, the control device 10 controls the motor generator 4 so that the driver's requested torque is satisfied by the motor torque.

[0036] E / G running is a running state in which the engine 2 is operated to run the hybrid vehicle 1 using the power (hereinafter also referred to as engine torque) of the engine 2. During E / G running, the control device 10 controls the engine 2 so that the driver's requested torque is satisfied by the engine torque.

[0037] HEV driving is a driving state in which the engine 2 is operated and the hybrid vehicle 1 is driven by the power of the engine 2 and the power of the motor generator 4. During HEV driving, the control device 10 controls the engine 2 and the motor generator 4 so that the total torque obtained by adding the engine torque and the motor torque satisfies the driver's requested torque.

[0038] The control device 10 switches the driving mode between EV driving, E / G driving, and HEV driving depending on the state of the hybrid vehicle 1, for example, the state of charge of the high-voltage battery 40, the temperature state of the clutch 32, and the like.

[0039] Next, with reference to FIG. 3, a flow of control for switching the driving mode when the hybrid vehicle 1 starts, which is executed by the control device 10, will be described.

[0040] In the hybrid vehicle 1 of this embodiment, the power of the engine 2 is transmitted to the drive wheels 5 via the clutch 32. Therefore, if the vehicle is repeatedly started using the power of the engine 2, i.e., started using E / G running, for example, in a traffic jam, the clutch 32 may overheat due to heat generated by a partial clutch. Therefore, in such a situation where the clutch 32 may overheat, priority is given to starting using EV running, which does not require power transmission by the clutch 32 (hereinafter, this may also be referred to as "EV start"). Furthermore, in this embodiment, the amount of charge of the high-voltage battery 40 is also taken into consideration, and switching control of the driving mode at start-up is performed so as to give priority to the EV start described above.

[0041] 3, the control device 10 acquires the clutch temperature from the clutch temperature sensor 13 (step S1). The control device 10 may acquire the clutch temperature by estimation.

[0042] Next, the control device 10 determines whether the clutch temperature acquired in step S1 is equal to or higher than a predetermined temperature Ton (step S2).

[0043] The predetermined temperature Ton is the lower limit of the clutch temperature at which it is determined that there is a high possibility that the clutch 32 will overheat (become in an overheated state) unless the load on the clutch 32 is reduced, and is determined in advance through experimentation and stored in the ROM of the control device 10. The predetermined temperature Ton is a temperature lower than the clutch temperature at which it is determined that the clutch 32 is overheated (becomes in an overheated state).

[0044] If the control device 10 determines in step S2 that the clutch temperature is not equal to or higher than the predetermined temperature Ton, it determines that the clutch 32 is unlikely to overheat (to reach an overheated state), and terminates this switching control. In this case, the control device 10 selects one of the driving modes of EV driving, E / G driving, and HEV driving depending on the state of the hybrid vehicle 1.

[0045] If the control device 10 determines in step S2 that the clutch temperature is equal to or higher than the predetermined temperature Ton, it determines whether the charge amount of the high-voltage battery 40 is equal to or higher than a predetermined charge amount Cth (step S3).

[0046] If the control device 10 determines in step S3 that the charge amount of the high-voltage battery 40 is not equal to or greater than the predetermined charge amount Cth, it determines that it is difficult to start the vehicle in EV mode, prioritizes starting the vehicle by E / G running (step S4), and returns the process to step S3. As a result, EV starting is restricted, and the motor generator 4 generates electricity to charge the high-voltage battery 40.

[0047] If the control device 10 determines in step S3 that the charge amount of the high-voltage battery 40 is equal to or greater than the predetermined charge amount Cth, the control device 10 disengages the clutch 32 to reduce the load on the clutch 32, and prioritizes EV start (step S5). At this time, the control device 10 also acquires the clutch temperature.

[0048] Next, the control device 10 determines whether the clutch temperature acquired in step S5 is equal to or lower than the release temperature Toff (step S6).

[0049] The release temperature Toff is a temperature lower than the predetermined temperature Ton, and is the upper limit of the clutch temperature at which it is determined that the clutch 32 has cooled to a level at which it is determined that there is no or very little possibility of the clutch 32 overheating (overheating state) even when the clutch 32 is in an engaged state. The release temperature Toff is experimentally determined in advance and stored in the ROM of the control device 10. For example, the release temperature Toff is set based on the clutch temperature that the clutch 32 drops to when it continues to be disengaged for about one minute after reaching the predetermined temperature Ton. Specifically, it is preferable to set the release temperature Toff to a clutch temperature that is about 30°C lower than the predetermined temperature Ton. Note that the aforementioned one minute and 30°C are merely examples and are not limiting. Optimal times and temperatures are applied as appropriate depending on the specifications of the clutch 32, such as the capacity of the clutch 32.

[0050] If the control device 10 determines in step S6 that the clutch temperature is not equal to or lower than the release temperature Toff, the control device 10 returns the process to step S5.

[0051] When the control device 10 determines in step S6 that the clutch temperature is equal to or lower than the release temperature Toff, it performs normal control, that is, sets the driving mode to HEV driving (step S7), and ends this switching control.

[0052] Next, referring to Figures 4 and 5, we will explain the necessity of "EV start" of the hybrid vehicle 1 and the possibility of "EV driving" by comparing an example of changes when the charge amount of the high-voltage battery 40 is low (Figure 4) with an example of changes when the charge amount is high (Figure 5).

[0053] In the hybrid vehicle 1 of this embodiment, when starting, the vehicle basically starts by E / G running (running using the driving force of the engine 2) regardless of the charge level of the high-voltage battery 40. In other words, the clutch 32 is engaged (half-clutch) and the vehicle starts using the driving force of the engine 2, and EV starting is restricted.

[0054] The change in the vehicle state shown in Figure 4 is a change from a state (time t0) in which the charge level of the high-voltage battery 40 is low. In other words, it shows a state change in which the clutch temperature changes from low to high and then back to low when the charge level is low. In this case, that is, when the charge level of the high-voltage battery 40 is not equal to or greater than the predetermined charge level Cth and the clutch temperature is relatively low, the vehicle starts running by E / G from time t0 according to basic control. Furthermore, power is generated by the engine 2 to increase the charge level of the high-voltage battery 40, and the charge level gradually increases.

[0055] Thereafter, for example, as the vehicle repeatedly starts and stops due to traffic congestion, a load is placed on the clutch 32, causing the clutch temperature to rise.

[0056] Then, at time t1, the clutch temperature reaches a predetermined temperature Ton. To reduce the clutch temperature, it would be desirable to perform an EV start without using the clutch 32. However, because the charge level of the high-voltage battery 40 is less than the predetermined charge level Cth at this time, the restriction on EV start continues. That is, starting by E / G running continues, and power generation by the motor generator 4 continues. This charges the high-voltage battery 40. Furthermore, because starting by E / G running continues after time t1, the clutch temperature continues to rise. Furthermore, because the charge level of the high-voltage battery 40 is less than the predetermined charge level Cth, EV running is restricted. By restricting EV running, power consumption is reduced and power is conserved, and charge is prioritized to allow EV start that addresses clutch overheating by increasing the charge level early. Furthermore, restricting EV running and performing E / G running rotates the clutch, promoting clutch heat dissipation. In other words, although the clutch 32 is used during E / G running, the clutch 32 is cooled by the rotation of the clutch, as the clutch is engaged for a shorter period of time than during starting.

[0057] Subsequently, at time t2, when the charge amount of the high-voltage battery 40 reaches or exceeds a predetermined charge amount Cth while the clutch temperature remains above a predetermined temperature Ton, the restriction on EV start is lifted, and EV start becomes possible. Therefore, from time t2 onwards, EV start is performed without partially engaging the clutch 32. As a result, from time t2 onwards, the load on the clutch 32 decreases, and the clutch temperature drops. Furthermore, as power is consumed during EV start, the charge amount of the high-voltage battery 40 decreases. At this time, the charge amount drops below the predetermined charge amount Cth, but EV start is still permitted until the clutch temperature drops below the release temperature Toff. The restriction on EV driving is also maintained to conserve power and enable EV start to be performed as long as possible while preventing clutch overheating.

[0058] The change in the vehicle state shown in Figure 5 is a change from a state (time t0) in which the high-voltage battery 40 is highly charged. In other words, it shows a state change in which the clutch temperature changes from low to high and then back to low when the battery is highly charged. In this case, that is, when the high-voltage battery 40 is charged to a predetermined charge level Cth or more and the clutch temperature is relatively low, the vehicle starts running by E / G from time t0 according to basic control. Furthermore, the high-voltage battery 40 is highly charged, making EV running and HEV running possible, and the charge level gradually decreases.

[0059] Thereafter, for example, as the vehicle repeatedly starts and stops due to traffic congestion, a load is placed on the clutch 32, causing the clutch temperature to rise.

[0060] Then, at time t11, the clutch temperature reaches a predetermined temperature Ton. At this time, because the charge amount of the high-voltage battery 40 is equal to or greater than the predetermined charge amount Cth, the restriction on EV start is lifted, and EV start becomes possible. As a result, from time t11 onwards, EV start is performed without partially engaging the clutch 32. Therefore, from time t11 onwards, the load on the clutch 32 decreases, and the clutch temperature drops. In addition, EV driving is restricted to reduce consumption and conserve power, and control is performed to disable EV driving so that EV start can be performed for as long as possible in response to clutch overheating.

[0061] Thereafter, at time t12, when the clutch temperature drops below the release temperature Toff, the priority for EV start is released, and priority is given to starting using E / G running. At time t12, the charge level of the high-voltage battery 40 is less than the predetermined charge level Cth, so the restriction on EV running continues. Control is performed to prioritize charging by restricting EV running, reducing consumption, and increasing the charge level early. At time t13, when the charge level of the high-voltage battery 40 reaches the predetermined charge level Cth, the restriction on EV running is released. In the example shown in FIG. 5, it is assumed that traffic congestion continues even after time t12, causing repeated starting and stopping.

[0062] As described above, in the hybrid vehicle of this embodiment, when the charge amount of the high-voltage battery 40 is equal to or greater than the predetermined charge amount Cth and the clutch temperature is equal to or greater than the predetermined temperature Ton, the clutch 32 is disengaged and the power of the motor generator 4 is transmitted to the drive wheels 5 to start (EV start), so the load on the clutch 32 can be reduced taking into account the charge amount of the high-voltage battery 40.

[0063] Furthermore, in the hybrid vehicle according to this embodiment, when the clutch temperature is equal to or higher than a predetermined temperature Ton and the charge amount of the high-voltage battery 40 is less than a predetermined charge amount Cth, the clutch 32 is connected and power from the engine 2 is transmitted to the drive wheels 5 to start the vehicle (start by E / G running), while the high-voltage battery 40 is charged by the power generated by the motor generator 4. Therefore, it is possible to ensure a charge amount that allows, for example, multiple EV starts before the clutch 32 overheats. This makes it possible to start the vehicle in EV mode before the clutch 32 overheats, and allows the clutch 32 to cool.

[0064] Furthermore, in the hybrid vehicle according to this embodiment, the predetermined temperature Ton is lower than the temperature at which the clutch 32 is determined to be in an overheated state. Therefore, when the charge level of the high-voltage battery 40 is low, an opportunity is ensured to generate electricity through E / G running in order to ensure a charge level that will enable EV start, and when the charge level of the high-voltage battery 40 is high, EV start can be performed quickly before the clutch 32 overheats, thereby allowing the clutch 32 to cool down quickly.

[0065] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0066] 1 Hybrid vehicle 2 engines 3 Transmission 4 Motor generator (motor) 5 drive wheels 10 Control device 13 Clutch temperature sensor 15 Engine ECU 16 Battery Management Controller 31 Transmission mechanism 32 Clutch 40 High voltage battery (battery) Cth Predetermined charge amount Ton Predetermined temperature Toff release temperature

Claims

1. an engine capable of transmitting power to drive wheels via a clutch; a motor capable of transmitting power to the drive wheels without using the clutch; a battery for supplying power to the motor; a control device that disengages the clutch and transmits the power of the motor to the drive wheels to start the vehicle when the charge amount of the battery is equal to or greater than a predetermined charge amount and the temperature of the clutch is equal to or greater than a predetermined temperature; A hybrid vehicle equipped with

2. 2. The hybrid vehicle according to claim 1, wherein, when the temperature of the clutch is equal to or higher than a predetermined temperature and the charge amount of the battery is less than a predetermined charge amount, the control device connects the clutch to transmit power from the engine to the drive wheels to start the vehicle while charging the battery by generating electricity from the motor.

3. 3. The hybrid vehicle according to claim 1, wherein the predetermined temperature is lower than a temperature at which the clutch is determined to be in an overheated state.

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