Control system of a vehicle

Abstract

This invention provides a vehicle control system. In the control system of a vehicle having an engine and a motor and a torque converter disposed between the motor and the drive wheels, the torque converter is suppressed from overheating during uphill driving. The vehicle control system (1) has an engine (2) and a motor (3) that generate torque for driving the vehicle, a first clutch (CL1) disposed between the engine and the motor in a disengageable manner, a transmission (7) disposed on the power transmission path between the motor and the drive wheels, a torque converter (5) and a lock-up clutch (6), and a control device (20) for controlling the engine, the motor, the first clutch and the lock-up clutch. When the vehicle is traveling uphill using at least the torque of the engine, and the temperature of the torque converter has reached or exceeded a specified temperature, the control device engages the lock-up clutch and disengages the friction connection.

Description

Technical Field

[0001] This invention relates to a control system for a vehicle having an engine, a motor, a torque converter disposed between the motor and the drive wheels, and a lock-up clutch. Background Technology

[0002] This technology is described, for example, in Patent Document 1. Patent Document 1 describes a technology in which the lock-up clutch is disengaged when the vehicle is traveling uphill, in a hybrid vehicle having an internal combustion engine, an electric generator, an automatic transmission, a torque converter, and a lock-up clutch. In this technology, discomfort caused to the driver by deceleration is suppressed during uphill driving, thereby improving the driving experience.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2000-151307 Summary of the Invention

[0004] The problem that the invention aims to solve In vehicles with torque converters as described above, when driving uphill using at least the engine's torque (or possibly the motor's torque in addition to the engine's), the turbine inside the torque converter sometimes slips, causing the torque converter to overheat. In vehicles with motors and batteries, the cooling capacity available for the torque converter is reduced because these components need to be cooled. Therefore, it is generally considered sufficient to suppress the torque converter's overheating during uphill driving.

[0005] The present invention was made to solve the problems of the prior art mentioned above, and its purpose is to suppress the overheating of the torque converter during uphill driving in the control system of a vehicle having an engine, a motor and a torque converter disposed between the motor and the drive wheels.

[0006] Methods for solving problems To achieve the above objectives, the present invention provides a vehicle control system, characterized by comprising: an engine and a motor that generate torque for driving the vehicle; a friction coupling disposed between the engine and the motor in a disengageable and connectable manner; a transmission, a torque converter, and a lock-up clutch disposed on the power transmission path between the motor and the vehicle's drive wheels; and a control device configured to control the engine, the motor, the friction coupling, and the lock-up clutch; the control device being configured to engage the lock-up clutch and disengage the friction coupling when the vehicle is traveling uphill using at least the engine's torque, and the torque converter's temperature has reached or exceeded a predetermined temperature.

[0007] In this invention, during uphill driving using at least the engine torque (in which case the friction coupling is engaged), when the torque converter reaches a relatively high temperature, the lock-up clutch is engaged and the friction coupling is disengaged. By engaging the lock-up clutch, transmission losses in the torque converter can be suppressed, thus preventing the torque converter from overheating during uphill driving. Furthermore, by disengaging the friction coupling, the transmission of engine torque downstream is cut off, and only the motor torque is transmitted downstream. This allows the vehicle to use the motor torque to drive uphill, preventing the engine from stalling due to low engine speed during uphill driving.

[0008] In this invention, it is preferred that the control device is configured to allow the engine to idle while engaging the lock-up clutch and disengaging the friction coupling.

[0009] According to the present invention configured in this way, by running the engine at idle speed, it is not necessary to ensure the motor has spare power for starting the engine, and the vehicle can reliably go uphill by means of the motor torque.

[0010] In this invention, it is preferred that the control device is configured to increase the torque of the motor while engaging the lock-up clutch and disengaging the friction coupling.

[0011] According to the present invention configured in this way, by increasing the motor torque, the vehicle can reliably climb hills using the motor torque.

[0012] In this invention, it is preferred that the control device is configured to engage the lock-up clutch and disengage the friction connection when the road surface slope of the uphill road is above a predetermined value.

[0013] According to the present invention configured in this way, it is possible to engage the lock-up clutch and disengage the friction connection on a relatively steep uphill slope where the torque converter generates heat.

[0014] In this invention, it is preferred that the control device is configured to engage the lock-up clutch and disengage the friction connection when the vehicle speed is less than a predetermined speed.

[0015] According to the present invention configured in this way, it is possible to engage the lock-up clutch and disconnect the friction connection at relatively low vehicle speeds where the torque converter generates heat.

[0016] In this invention, it is preferred that the control device is configured to engage the lock-up clutch and disengage the friction connection when the SOC of the battery supplying power to the motor is above a predetermined value.

[0017] According to the present invention configured in this way, when the SOC (State of Charge) of the battery is such that the vehicle can be driven uphill by the motor torque generated by the battery power, the locking clutch can be engaged and the friction connection can be disengaged.

[0018] In this invention, preferably, the control device is configured such that, after engaging the lock-up clutch and disengaging the friction coupling, when the temperature of the torque converter becomes lower than a predetermined temperature, the lock-up clutch is disengaged and the friction coupling is engaged.

[0019] According to the present invention configured in this way, when the temperature of the torque converter is relatively low and there is no need to suppress the heating of the torque converter, the lock-up clutch can be disengaged and the friction connection can be connected.

[0020] In this invention, it is preferred that the control device is configured such that, after engaging the lock-up clutch and disengaging the friction connector, the friction connector is engaged when the vehicle speed becomes above a predetermined speed.

[0021] According to the present invention configured in this way, when the vehicle speed is relatively high and there is no need to suppress the heat generation of the torque converter, the lock-up clutch can be disengaged and the friction connection can be connected.

[0022] In this invention, it is preferred that the control device is configured such that, after engaging the lock-up clutch and disengaging the friction coupling, when the SOC of the battery supplying power to the motor becomes less than a predetermined value, the lock-up clutch is disengaged and the friction coupling is engaged.

[0023] According to the present invention configured in this way, when the SOC (state of charge) of the battery is not sufficient to enable the vehicle to climb a hill using the motor torque generated by the battery power, the lock-up clutch can be disengaged and the friction connection engaged to use the engine torque to climb the hill.

[0024] Invention Effects According to the present invention, in the control system of a vehicle having an engine and a motor and a torque converter disposed between the motor and the drive wheel, it is possible to suppress the torque converter from overheating during uphill driving. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the configuration of a vehicle control system according to an embodiment of the present invention.

[0026] Figure 2 This is a block diagram illustrating the electrical structure of the vehicle control system according to an embodiment of the present invention.

[0027] Figure 3 This is a timing diagram illustrating the uphill control in an embodiment of the present invention.

[0028] Figure 4This is a flowchart illustrating the start determination process of uphill control in an embodiment of the present invention.

[0029] Figure 5 This is a flowchart illustrating the end determination process of uphill control in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures 1. Vehicle control system 2 Engines 3 motors 4 batteries 5. Torque Converter 6. Lock-up clutch 7. Transmission 8 Power Transmission System 10 drive shafts 12 drive wheels 20 Control devices CL1 First Clutch CL2 Second Clutch Detailed Implementation

[0031] Hereinafter, the vehicle control system according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0032] [System Composition] First, refer to Figure 1 and Figure 2 The configuration of the vehicle control system according to this embodiment will be described. Figure 1 This is a schematic diagram illustrating the configuration of the vehicle control system according to this embodiment. Figure 2 This is a block diagram showing the electrical structure of the vehicle control system according to this embodiment.

[0033] like Figure 1 As shown, the vehicle control system 1 mainly includes: an engine (internal combustion engine) 2, which generates torque for driving the vehicle; a motor 3, which is located downstream of the engine 2 in the vehicle's power transmission path and generates torque for driving the vehicle; a battery 4, which exchanges power with the motor 3 via an inverter (not shown); a transmission (automatic transmission) 7, which is located downstream of the motor 3 in the vehicle's power transmission path and changes the rotational speed of the engine 2 and / or the motor 3; a power transmission system 8, which transmits the torque from the transmission 7 downstream; a drive shaft 10, which drives drive wheels 12 using the torque from the power transmission system 8; and the drive wheels 12. The vehicle is configured as a hybrid vehicle that uses the engine 2 and the motor 3 as power sources.

[0034] The output shaft of engine 2 and the rotating shaft of motor 3 are coaxially connected via shaft AX1 through a first clutch CL1, which can be disconnected or connected. This first clutch CL1 allows for switching the transmission and disconnection of torque between engine 2 and motor 3. For example, the first clutch CL1 is a dry multi-plate clutch, which can continuously or progressively control the clutch oil flow and pressure using a motor (not shown) to change the transmitted torque capacity. Furthermore, the first clutch CL1 is equivalent to an example of a "friction connection" in this invention; however, a brake can also be used instead of a clutch as this friction connection.

[0035] A torque converter 5 and a lock-up clutch 6 are provided between the motor 3 and the transmission 7. In other words, the transmission 7 is configured as a torque converter-type automatic transmission with a lock-up clutch. The torque converter 5 is configured to connect shaft AX2, which is connected to the rotating shaft of the motor 3, and shaft AX3, which is connected to the rotating shaft of the transmission 7. The lock-up clutch 6 is configured to connect these shafts AX2 and AX3. For example, the torque converter 5 has a pump (not shown) fixed to a housing (not shown) and a turbine (not shown) driven by the pump. The rotation of the turbine is output to the transmission 7 via shaft AX3. The lock-up clutch 6 is configured to directly connect the turbine and shaft AX2 via the housing of the torque converter 5.

[0036] The transmission 7 internally possesses one or more planetary gears, capable of automatically switching gear levels (gear ratios) based on vehicle speed, engine speed, and other factors. Furthermore, the transmission 7 internally includes a second clutch CL2 that can be engaged or disengaged. This second clutch CL2 switches the transmission and disconnection of torque between the upstream side (engine 2 and motor 3) and the downstream side (drive wheel 12, etc.) of the transmission 7. For example, the second clutch CL2 is also composed of a dry multi-plate clutch, capable of continuously or stepwise controlling the clutch oil flow and pressure using a motor (not shown) to change the transmitted torque capacity. Moreover, the second clutch CL2 is actually composed of multiple clutches used for switching various gear levels within the transmission 7.

[0037] Torque is input to the power transmission system 8 via the output shaft AX4 of the transmission 7. The power transmission system 8 is configured to include differential gears that distribute driving force to a pair of left and right drive wheels 12, end-drive gears, etc.

[0038] The aforementioned vehicle can switch driving modes by switching the engagement and disengagement of the first clutch CL1. That is, the vehicle has a driving mode in which the first clutch CL1 is disengaged, and the vehicle is driven using the torque of the motor 3 instead of the torque of the engine 2; and a driving mode in which the first clutch CL1 is engaged, and the vehicle is driven using at least the torque of the engine 2. The former driving mode is the so-called EV driving mode, and the latter driving mode is either an engine driving mode that uses only the torque of the engine 2 to drive the vehicle, or a hybrid driving mode that uses the torque of both the engine 2 and the motor 3 to drive the vehicle.

[0039] Next, as Figure 2 As shown, the vehicle control system 1 of this embodiment also includes a control device 20 based on a known microcomputer and composed of circuits. The control device 20 includes one or more processors 20a that serve as a central processing unit (CPU) for executing programs, a memory 20b consisting of, for example, RAM (Random Access Memory) or ROM (Read Only Memory) that stores programs and data, and an input / output bus for inputting and outputting electrical signals. For example, the control device 20 may be composed of an ECU (Electronic Control Unit).

[0040] The control unit 20 receives signals from a vehicle speed sensor SN1 that detects the vehicle's speed, an acceleration sensor SN2 that detects the vehicle's acceleration, an ATF temperature sensor SN3 that detects the temperature of the automatic transmission fluid (ATF) in the transmission 7, and a SOC sensor SN4 that detects the state of charge (SOC) of the battery 4. The control unit 20 then controls the engine 2, the motor 3, the lock-up clutch 6, and the first clutch CL1 based on these signals. Furthermore, the control unit 20 is not limited to detecting the SOC of the battery 4 using the SOC sensor SN4; the SOC can also be calculated based on the charging and discharging activity of the battery 4.

[0041] [Control Content] Next, the control performed by the control device 20 will be specifically described in this embodiment. In this embodiment, when the vehicle is traveling uphill using at least engine torque (in which case the first clutch CL1 is engaged, typically during uphill travel in hybrid driving mode), and the torque converter 5 becomes relatively hot, the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1 (hereinafter referred to as "uphill control"). By engaging the lock-up clutch 6, transmission losses in the torque converter 5 can be suppressed, thus suppressing overheating of the torque converter 5. Furthermore, by disengaging the first clutch CL1, the transmission of engine torque downstream is cut off, and only the motor torque is transmitted downstream, thus enabling the vehicle to climb the hill using only the motor torque. If engine torque is used uphill, the engine 2 will become low-speed due to the low vehicle speed, potentially causing it to stall. However, by disengaging the first clutch CL1 and separating the engine 2 to use the motor torque for uphill travel, such stalling can be prevented.

[0042] Furthermore, in this embodiment, when the lock-up clutch 6 is engaged and the first clutch CL1 is disengaged as described above, the motor torque is increased to enable the motor 3 to climb the hill, while the engine 2 is allowed to idle. By allowing the engine 2 to idle without stopping it, there is no need to ensure sufficient power in the motor 3 for starting the engine. Therefore, the vehicle can reliably climb the hill using the torque of the motor 3.

[0043] Next, refer to Figure 3 The timing diagram representing the uphill control in this embodiment will be explained. Figure 3 The diagram, from top to bottom, shows the accelerator opening, the temperature of torque converter 5 (hereinafter appropriately referred to as "torque converter temperature"), the torque (transmitted torque) of the first clutch CL1, the torque (transmitted torque) of the lock-up clutch 6, the speed, and the torque. Figure 3 In the diagram, regarding engine speed, the solid line represents engine speed, the dashed line represents motor speed, and the single-dot-dash line represents turbine speed within torque converter 5. Additionally, regarding torque at the bottom, the solid line represents engine torque, and the dashed line represents motor torque.

[0044] like Figure 3 As shown, firstly, at time t1, the accelerator opening increases to allow the vehicle to climb the hill. In this situation, since the vehicle is set to hybrid driving mode, the first clutch CL1 is engaged, and the engine speed matches the motor speed. On the other hand, since the lock-up clutch 6 is disengaged, the turbine of the torque converter 5 is in a slippery state. This is because the vehicle is climbing the hill at a low speed. Therefore, after time t1, the torque converter temperature rises, and thus at time t2, the torque converter temperature reaches a relatively high specified temperature T1.

[0045] In this embodiment, at time t2, the first clutch CL1 is disengaged to reduce its transmitted torque, and the lock-up clutch 6 is engaged to increase its transmitted torque. Simultaneously, by idling the engine 2, the engine speed and torque decrease (specifically, the engine speed becomes idle speed, and the engine torque becomes approximately zero), while the motor torque is increased to allow the motor 3 to climb the hill. Then, at time t3, the first clutch CL1 is disengaged and the lock-up clutch 6 is engaged. By engaging the lock-up clutch 6 in this way, the motor speed and turbine speed become synchronized. According to the hill-climb control of this embodiment, after time t2, the heating of the torque converter 5 is suppressed, and the torque converter temperature decreases.

[0046] Next, refer to Figure 4 The flow of the start determination process for determining whether uphill control can begin, as described in this embodiment, will be explained. This process is repeatedly executed by the control device 20 at a predetermined cycle. Specifically, the processor 20a within the control device 20 reads the program stored in the memory 20b and executes the program, thereby realizing the control involved in this process.

[0047] First, in step S11, the control device 20 acquires various information from the vehicle's control system 1. In particular, the control device 20 acquires the vehicle speed detected by the vehicle speed sensor SN1, the acceleration detected by the acceleration sensor SN2, the ATF temperature detected by the ATF temperature sensor SN3, and the SOC of the battery 4 detected by the SOC sensor SN4.

[0048] Next, in step S12, the control device 20 determines whether the vehicle is set to hybrid driving mode. For example, the control device 20 determines whether the vehicle is set to hybrid driving mode based on the state of the first clutch CL1 and the relationship between the engine speed and the motor speed. In this example, the control device 20 determines that the vehicle is set to hybrid driving mode when the first clutch CL1 is engaged or when the engine speed and the motor speed are the same. If the control device 20 determines that the vehicle is set to hybrid driving mode (step S12: Yes), it proceeds to step S13; if it does not determine that the vehicle is set to hybrid driving mode (step S12: No), for example, if the vehicle is set to EV driving mode, it exits the process.

[0049] Next, in step S13, the control device 20 determines whether the road surface slope of the vehicle's driving lane is above a predetermined value. Here, the control device 20 determines whether the vehicle's driving lane is a relatively steep uphill road for which the uphill control of this embodiment should be performed. For example, the control device 20 calculates the road surface slope based on the acceleration obtained in step S11. In addition, the predetermined value used to determine the road surface slope is, for example, 30%. Furthermore, it is not limited to calculating the road surface slope based on acceleration; a slope sensor can also be used to detect the road surface slope. If the result of step S13 is that the control device 20 determines that the road surface slope is above the predetermined value (step S13: Yes), the process proceeds to step S14. If it does not determine that the road surface slope is above the predetermined value (step S13: No), that is, if the road surface slope is less than the predetermined value, the process exits.

[0050] Next, in step S14, the control device 20 determines whether the vehicle speed obtained in step S11 is less than a specified speed. At a relatively low vehicle speed, the turbocharger slips, creating a speed difference within the torque converter 5, causing the torque converter 5 to heat up. Conversely, at a relatively high vehicle speed, the turbocharger speed increases, eliminating the speed difference within the torque converter 5, and the torque converter 5 no longer heats up. Therefore, in step S14, it is determined whether this is a relatively low vehicle speed at which the torque converter 5 heats up. For example, the specified speed used to determine the vehicle speed is 10 km / h. If the result of step S14 is that the control device 20 determines the vehicle speed is less than the specified speed (step S14: Yes), it proceeds to step S15; if it does not determine the vehicle speed is less than the specified speed (step S14: No), that is, if the vehicle speed is above the specified speed, it exits the process.

[0051] Next, in step S15, the control device 20 determines whether the torque converter temperature is above a predetermined temperature. Here, the control device 20 determines whether the torque converter temperature is a relatively high temperature at which the uphill control of this embodiment should be performed, that is, whether the torque converter temperature should be reduced. For example, the control device 20 calculates the torque converter temperature based on the slip amount within the torque converter 5. In this case, the control device 20 may also consider the ATF temperature obtained in step S11 to calculate the torque converter temperature. Furthermore, it is not limited to calculating the torque converter temperature; a temperature sensor can also be used to detect the torque converter temperature. If the result of step S15 is that the control device 20 determines that the torque converter temperature is above the predetermined temperature (step S15: Yes), the process proceeds to step S16; if it does not determine that the torque converter temperature is above the predetermined temperature (step S15: No), that is, if the torque converter temperature is below the predetermined temperature, the process exits.

[0052] Next, in step S16, the control device 20 determines whether the SOC obtained in step S11 is above a predetermined value. Here, the control device 20 determines whether the SOC (charge amount) of the battery 4 is sufficient to generate enough motor torque to propel the vehicle uphill using the power from the battery 4. If the result of step S16 is that the control device 20 determines that the SOC is above the predetermined value (step S16: Yes), the process proceeds to step S17; if the control device 20 does not determine that the SOC is above the predetermined value (step S16: No), that is, if the SOC is below the predetermined value, the process exits.

[0053] If all the conditions in steps S12 to S16 described above are met, the control device 20 proceeds to step S17 to perform the uphill control of this embodiment. In step S17, the control device 20 controls the disengagement of the first clutch CL1, while simultaneously controlling the engagement of the lock-up clutch 6 in step S18. For example, the control device 20 controls the hydraulic pressure applied to the clutches in a manner that adjusts their transmitted torque in order to disengage / engage these clutches. Then, the control device 20 exits the process after step S18.

[0054] Next, refer to Figure 5 The process for determining whether uphill control can be terminated, as described in this embodiment, will be explained. This process is also repeatedly executed by the control device 20 at a predetermined cycle.

[0055] First, in step S21, the control device 20 acquires various information from the vehicle's control system 1. In particular, the control device 20 acquires the vehicle speed detected by the vehicle speed sensor SN1, the acceleration detected by the acceleration sensor SN2, the ATF temperature detected by the ATF temperature sensor SN3, and the SOC of the battery 4 detected by the SOC sensor SN4.

[0056] Next, in step S22, the control device 20 determines whether the vehicle speed obtained in step S21 is less than a predetermined speed. The intention of this determination in step S22 is... Figure 4The determination in step S14 is the same. If the result of step S22 is that the control device 20 determines the vehicle speed is less than a predetermined speed (step S22: Yes), it proceeds to step S23 to continue the uphill control of this embodiment. Conversely, if the control device 20 does not determine the vehicle speed is less than a predetermined speed (step S22: No), that is, if the vehicle speed is above the predetermined speed, it proceeds to step S26. In this case, since the vehicle speed is relatively high, the torque converter 5 no longer heats up. Therefore, the control device 20 controls the engagement of the first clutch CL1 in step S26 to end the uphill control of this embodiment. Furthermore, even when the vehicle speed is relatively high, it is not a problem to maintain the engagement of the lock-up clutch 6, so the control device 20 maintains the engagement of the lock-up clutch 6.

[0057] Next, in step S23, the control device 20 determines whether the torque converter temperature is above a specified temperature. The intention behind this determination in step S23 is also related to... Figure 4 The determination in step S15 is the same. If the result of step S23 is that the control device 20 determines that the torque converter temperature is above the specified temperature (step S23: Yes), it proceeds to step S24 to continue the uphill control of this embodiment. Conversely, if the control device 20 does not determine that the torque converter temperature is above the specified temperature (step S23: No), that is, if the torque converter temperature is below the specified temperature, it proceeds to step S25. In this case, since the torque converter temperature is relatively low, it can be said that there is no need to suppress the heating of the torque converter 5. Therefore, in order to end the uphill control of this embodiment, the control device 20 performs control to disengage the lock-up clutch 6 in step S25, and at the same time performs control to engage the first clutch CL1 in step S26.

[0058] Next, in step S24, the control device 20 determines whether the SOC obtained in step S21 is above a predetermined value. The intention behind this determination in step S24 is also related to... Figure 4The determination in step S16 is the same. If the result of step S24 is that the control device 20 determines that the SOC is above the specified value (step S24: Yes), it exits the process. In this case, since all the conditions of steps S22 to S24 described above are met, the control device 20 continues to perform the uphill control of this embodiment. In contrast, if the control device 20 does not determine that the SOC is above the specified value (step S24: No), that is, if the SOC is less than the specified value, it proceeds to step S25. In this case, the SOC (charge amount) of the battery 4 is not enough to enable the vehicle to go uphill using the motor torque generated by the power of the battery 4. Therefore, in order to end the uphill control of this embodiment (more specifically, to end the uphill control, set the hybrid driving mode, and use the engine torque to go uphill), the control device 20 performs the control of disengaging the lock-up clutch 6 in step S25, and at the same time performs the control of engaging the first clutch CL1 in step S26.

[0059] [Functions and Effects] Next, the operation and effects of the vehicle control system 1 according to this embodiment will be explained. According to this embodiment, when the vehicle is traveling uphill using at least engine torque, and the torque converter temperature has reached or exceeded a predetermined temperature, the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1. By engaging the lock-up clutch 6, transmission losses in the torque converter 5 can be suppressed, thus preventing the torque converter 5 from overheating during uphill travel. Furthermore, by disengaging the first clutch CL1, the transmission of engine torque downstream is cut off, and only the motor torque is transmitted downstream. This allows the vehicle to use motor torque to go uphill, preventing the engine 2 from stalling due to low-speed operation during uphill travel.

[0060] Furthermore, according to this embodiment, the control device 20 simultaneously engages the lock-up clutch 6 and disengages the first clutch CL1 while the engine 2 idles. Therefore, it is not necessary to ensure sufficient spare power in the motor 3 for starting the engine, and the vehicle can reliably climb hills using the motor torque.

[0061] Furthermore, according to this embodiment, the control device 20 increases the motor torque while engaging the lock-up clutch 6 and disengaging the first clutch CL1. This allows the vehicle to reliably ascend a hill using the motor torque.

[0062] Furthermore, according to this embodiment, the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1 when the road surface gradient of the uphill road is above a predetermined value. Therefore, it is possible to control the engagement of the lock-up clutch 6 and disengagement of the first clutch CL1 on relatively steep uphill roads where the torque converter 5 generates heat.

[0063] Furthermore, according to this embodiment, the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1 when the vehicle speed is below a predetermined speed. Therefore, it is possible to control the engagement of the lock-up clutch 6 and the disengagement of the first clutch CL1 at relatively low vehicle speeds where the torque converter 5 generates heat.

[0064] Furthermore, according to this embodiment, the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1 when the SOC of the battery 4 is above a predetermined value. Therefore, when the SOC (charge level) of the battery 4 is sufficient to generate enough motor torque to propel the vehicle uphill, control can be performed to engage the lock-up clutch 6 and disengage the first clutch CL1.

[0065] Furthermore, according to this embodiment, after the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1, it disengages the lock-up clutch 6 and engages the first clutch CL1 when the torque converter temperature drops below a predetermined temperature. Therefore, when the torque converter temperature is relatively low and there is no need to suppress the heating of the torque converter 5, the lock-up clutch 6 can be disengaged and the first clutch CL1 engaged.

[0066] Furthermore, according to this embodiment, after the control device 20 engages the lock-up clutch 6 and disengages the first clutch CL1, it disengages the lock-up clutch 6 and engages the first clutch CL1 when the vehicle speed reaches a predetermined speed or higher. Therefore, when the vehicle speed is relatively high and there is no need to suppress the heating of the torque converter 5, it is possible to disengage the lock-up clutch 6 and engage the first clutch CL1.

[0067] Furthermore, according to this embodiment, after engaging the lock-up clutch 6 and disengaging the first clutch CL1, the control device 20 disengages the lock-up clutch 6 and engages the first clutch CL1 when the SOC of the battery 4 becomes less than a predetermined value. Thus, when the SOC (charge level) of the battery 4 is not sufficient to allow the vehicle to climb a hill using the motor torque generated by the power from the battery 4, the lock-up clutch 6 can be disengaged and the first clutch CL1 engaged to utilize engine torque for hill climbing.

[0068] [Variation Example] In the above-described embodiment, engine 2 is operated at idle speed, meaning that torque is not substantially generated from engine 2. However, in a modified embodiment, engine 2 can be operated in a manner that generates torque, providing assistance for uphill climbing using motor torque. In other words, engine torque can be used in addition to motor torque for uphill climbing. In this case, the first clutch CL1 is set to a semi-engaged state to transmit engine torque to the motor 3 side. Furthermore, such control can be performed, for example, when the SOC of battery 4 is low.

Claims

1. A vehicle control system, characterized in that, have: Engines and motors generate torque to drive vehicles; A friction connector is disposed between the engine and the motor in a manner that allows it to be disconnected or connected. The transmission, torque converter, and lock-up clutch are disposed on the power transmission path between the motor and the drive wheels of the vehicle; as well as The control device is configured to control the engine, the motor, the friction connector, and the lock-up clutch; The control device is configured to engage the lock-up clutch and disengage the friction connection when the vehicle is traveling uphill using at least the torque of the engine, and the temperature of the torque converter has reached or exceeded a specified temperature.

2. The vehicle control system according to claim 1, characterized in that, The control device is configured to allow the engine to idle while simultaneously engaging the lock-up clutch and disengaging the friction coupling.

3. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured to increase the torque of the motor while engaging the lock-up clutch and disengaging the friction coupling.

4. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured to engage the lock-up clutch and disengage the friction connection when the road surface slope of the uphill road is above a specified value.

5. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured to engage the lock-up clutch and disengage the friction connection when the vehicle speed is less than a specified speed.

6. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured to engage the lock-up clutch and disengage the friction connection when the SOC of the battery supplying power to the motor is above a predetermined value.

7. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured such that, after engaging the lock-up clutch and disengaging the friction coupling, when the temperature of the torque converter becomes lower than the specified temperature, it disengages the lock-up clutch and engages the friction coupling.

8. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured such that, after engaging the lock-up clutch and disengaging the friction connector, it engages the friction connector when the vehicle speed reaches or exceeds a predetermined speed.

9. The vehicle control system according to claim 1 or 2, characterized in that, The control device is configured such that, after engaging the lock-up clutch and disengaging the friction connector, when the SOC of the battery supplying power to the motor becomes less than a predetermined value, the lock-up clutch is disengaged and the friction connector is engaged.

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