Power transmission control device

Abstract

Power transmission control device for a vehicle (1) equipped with an automated manual transmission (3), the power transmission control device comprising: a clutch control unit (20) that controls a clutch (4) to change a drive torque transmitted from a drive source (2) of the vehicle to the automated manual transmission (3); and a calculation unit (21) for a required braking torque which, according to an inclination of a running surface of the vehicle (1) to a direction of travel, calculates a required braking torque which is necessary to maintain a stopped state of the vehicle (1), wherein the power transmission control device is characterized in that the calculation unit (21) for a required braking torque calculates the required braking torque under the condition that the vehicle (1) is stopped on an upwardly directed surface which is inclined upwards to the direction of travel; Provided that the vehicle (1) is stopped on the upward-directed surface, the clutch control unit (20) identifies a braking torque from the vehicle's (1) braking device (6), provided that the accelerator pedal (14) is not in an actuated state, and controls the clutch (4) to cause the clutch (4) to transmit a drive torque in accordance with the required braking torque, provided that the required braking torque necessary to maintain the stopped state of the vehicle (1) is greater than the braking torque from the braking device (6), wherein the drive torque in accordance with the required braking torque corresponds to a torque obtained by subtracting the braking torque from the braking device (6) from the required braking torque necessary to maintain the stopped state of the vehicle (1); and Provided that the vehicle (1) is stopped on the upward-directed surface, the clutch control unit (20) controls the clutch (4) according to the operating conditions of the drive source (2) and a changed state of a shift position of the automated manual transmission (3) when the accelerator pedal (14) is in an actuated state, instead of controlling the clutch (4) to cause the clutch (4) to transmit the drive torque according to the required braking torque.

Description

Technical area

[0001] The present invention relates to power transmission control devices for vehicles with automated manual transmissions. State of the art

[0002] Japanese Patent Application Publication No. 2004-82996, referred to as Patent Document 1, discloses an example of conventional power transmission control devices for vehicles, each having an automated manual transmission (AST). The disclosed power transmission control device includes a brake for applying braking force to wheels, an actuator for driving the brake, and a control unit for controlling the actuator. The control unit controls the actuator in conjunction with the engagement of a clutch, thereby releasing the brake.

[0003] The above configuration proposed in Japanese Patent Application Publication No. 2004-82996 prevents the vehicle stopped on a running surface inclined upward to the traveling direction from rolling back in the opposite direction to the traveling direction, that is, sliding downward, during the stopped state or when starting. Literature listPatent document

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2004-82996 Brief descriptionTechnical problem

[0005] Unfortunately, the device proposed in Japanese Patent Application Publication No. 2004-82996 prevents the vehicle from skidding downwards using only the braking force from the brake. This requires at least an actuator for controlling a parking brake and a hill start device for maintaining hydraulic pressure of the brake, resulting in an increase in the number of components installed in the vehicle.

[0006] The present invention aims to solve such a problem and aims to provide power transmission control devices each capable of preventing downward slippage of a vehicle equipped with an ASG without increasing the number of components installed in the vehicle. Problem solving

[0007] A power transmission control device according to one aspect of the present invention is a power transmission control device for a vehicle equipped with an automated manual transmission. The power transmission control device includes a clutch control unit that controls a clutch to change a drive torque transmitted from a power source of the vehicle to the automated manual transmission. The power transmission control device includes a required braking torque calculation unit that calculates a braking torque required to maintain a stopped state of the vehicle according to an inclination of a running surface of the vehicle to a traveling direction.The clutch control unit controls the clutch to cause the clutch to transmit drive torque according to the braking torque calculated by the required braking torque calculating unit under the condition that the vehicle is stopped on a running surface inclined upward to the traveling direction. Advantageous effects of the invention

[0008] The above present invention provides power transmission control devices each capable of preventing downward slippage of a vehicle equipped with an ASG without increasing the number of components installed in the vehicle. Short description of the drawings Fig. 1 is a functional diagram illustrating the main components of a vehicle incorporating a power transmission control apparatus according to an embodiment of the present invention; Fig. 2 is a conceptual view illustrating a required braking torque characteristic curve to which the power transmission control apparatus of this embodiment of the present invention refers; Fig. 3 is a conceptual view illustrating a torque correction coefficient characteristic to which the power transmission control apparatus of this embodiment of the present invention relates; Fig. Fig. 4 is a conceptual view illustrating a drive torque characteristic to which the power transmission control apparatus of this embodiment of the present invention relates; and Fig. 5 is a flowchart illustrating power transmission control operations of the power transmission control apparatus according to this embodiment of the present invention. Description of the embodiment

[0009] In the following, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. With reference to Fig. 1, a vehicle 1 including a power transmission control device according to this embodiment includes an internal combustion engine 2, an ASG 3, a clutch 4, drive wheels 5, a brake device 6, and an electronic control unit (ECU) 7. The engine 2 serves as a power source for the vehicle 1. The clutch 4 transmits drive torque from the engine 2 to the ASG 3, and the drive torque is transmitted to the drive wheels 5. The brake device 6 serves to brake the vehicle 1.

[0010] The engine 2 according to this embodiment is configured as a four-stroke engine that performs a sequence of four strokes including an intake stroke, a compression stroke, a power stroke, and an exhaust stroke, and performs ignition between the compression stroke and the power stroke.

[0011] For example, the ASG 3 includes a transmission that is essentially identical to a synchromesh transmission and changes a shift position through several actuators (not shown) controlled by the ECU 7.

[0012] The clutch 4 includes an input disc plate coupled to an output shaft of the engine 2 and an output disc plate coupled to an input shaft of the ASG 3. The clutch 4 is configured such that an actuator controlled by the ECU 7 changes the degree of engagement between the input disc plate and the output disc plate (hereinafter referred to simply as the clutch engagement degree) to change the friction between the input and output disc plates. This changes a drive torque transmitted from the engine 2 to the ASG 3.

[0013] The braking device 6 is formed, for example, from disc brakes or drum brakes provided for respective wheels, including the drive wheels 5. The braking device 6 brakes each wheel in accordance with an actuation of a brake pedal 10 via a brake booster and actuators (not shown), thereby braking the vehicle 1.

[0014] The ECU 7 is configured as a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), a flash memory, input ports, output ports, and a network module.

[0015] The network module is capable of communicating with other ECUs via a Controlled Area Network (CAN) or an on-board local area network (LAN) that conforms to a standard, such as FlexRay.

[0016] In addition to various control constants and various characteristic curves, programs are stored in the ROM of the ECU 7. These programs cause the computer unit to function as the ECU 7. More specifically, the execution of the programs stored in the ROM causes the computer unit to function as the ECU 7.

[0017] Various sensors are connected to the input ports of the ECU 7; these sensors include an inclination sensor 11, a vehicle weight sensor 12, a brake position sensor 13, an accelerator pedal position sensor 15, and a vehicle speed sensor 16. The inclination sensor 11 measures the inclination of a running surface of the vehicle. The vehicle weight sensor 12 measures the weight of the vehicle 1. The brake position sensor 13 measures an operation amount of the brake pedal 10, which activates the braking device 6. The accelerator pedal position sensor 15 measures an operation amount of an accelerator pedal 14. The vehicle speed sensor 16 measures a vehicle speed. The weight of the vehicle 1 measured by the vehicle weight sensor 12 includes the weight of passengers and loads, including transported goods and fuel, and is referred to as an actual vehicle weight.

[0018] Various controlled target objects are connected to the output ports of the ECU 7; these controlled target objects include the actuator for controlling the clutch 4. The ECU 7 controls the various controlled target objects connected to the output ports according to information received from the various sensors connected to the input ports.

[0019] The inclination sensor 11 of this embodiment includes, for example, an acceleration sensor. The vehicle weight sensor 12 is configured to measure the actual vehicle weight, for example, according to the conditions of the suspensions provided for the respective wheels.

[0020] The actual vehicle weight may be calculated based on the amount of change in vehicle speed with respect to the amount of change in requested power for the engine 2 during acceleration or deceleration of the vehicle 1. In this case, the ECU 7 may serve as the weight sensor 12.

[0021] The vehicle speed sensor 16 is composed of, for example, wheel speed sensors for measuring the driven wheels of the wheels excluding the drive wheels 5. The ECU 7 averages the wheel speeds measured by the respective wheel speed sensors to thereby calculate the vehicle speed.

[0022] The ECU 7 of this embodiment includes a clutch control unit 20 that controls the clutch 4 to change the drive torque transmitted from the engine 2 to the ASG 3. The ECU 7 also includes a required braking torque calculation unit 21 that calculates, according to the inclination of a running surface of the vehicle 1 to the traveling direction, a braking torque required to maintain a stopped state of the vehicle. The braking torque required to maintain the stopped state of the vehicle 1 is hereinafter referred to as the required braking torque.

[0023] In detail, the ECU 7 is configured to calculate the inclination of the running surface of the vehicle 1 to the traveling direction according to the inclination measured by the inclination sensor 11. With reference to Fig. 2, a required braking torque map is stored in the ROM of the ECU 7, which map contains a relationship between the inclination of a running surface of the vehicle 1 relative to the direction of travel and the required braking torque. The required braking torque map is determined in advance based on experiments. The ECU 7 refers to the required braking torque map to thereby determine the required braking torque according to the inclination of the running surface of the vehicle 1 relative to the direction of travel.

[0024] The ECU 7 of this embodiment is configured to correct a braking torque required to maintain the stopped state of the vehicle 1 according to the actual vehicle weight. In detail, referring to Fig. 3, a torque correction coefficient map is stored in the ROM of the ECU 7. This map contains a relationship between the actual vehicle weight and a coefficient for correcting a required braking torque, which is simply referred to as a torque correction coefficient. The correction map for a required braking torque is determined in advance based on experiments.

[0025] The ECU 7 refers to the torque correction coefficient map to thereby determine a torque correction coefficient corresponding to the actual vehicle weight measured by the vehicle weight sensor 12. In addition, the ECU 7 multiplies the required braking torque determined by referring to the required braking torque map shown in Fig. 2, with the torque correction coefficient calculated with reference to the torque correction coefficient characteristic curve shown in Fig. 3. This corrects the required braking torque.

[0026] While the vehicle 1 is stopped on a running surface that slopes upward to the traveling direction and is referred to as an upward surface, the ECU 7 of this embodiment controls the clutch 4 to cause the clutch 4 to transmit drive torque under the condition that a required braking torque is larger than a braking torque by the braking device 6, the drive torque being represented as subtracting the braking torque by the braking device 6 from the required braking torque.

[0027] In detail, the ECU 7 identifies a braking torque by the braking device 6 according to the operation amount of the brake pedal 10 measured by the brake position sensor 13 under the condition that the vehicle 1 is kept in a stopped state. Then, the ECU 7 controls the clutch 4 to cause the clutch 4 to transmit a drive torque when a required braking torque is greater than the braking torque by the braking device 6, where the drive torque is represented as subtracting the braking torque by the braking device 6 from the required braking torque.

[0028] When the ECU 7 calculates the drive torque to be transmitted through the clutch 4, it changes the clutch engagement degree via the corresponding actuator to transmit the calculated drive torque from the engine 2 to the ASG 3.

[0029] In detail, with reference to Fig. 4, a drive torque map is stored in the ROM of the ECU 7, which map contains a relationship between the clutch engagement degree and the drive torque when the engine 2 is idling. The drive torque map is determined in advance based on experiments. The ECU 7 refers to the drive torque map to thereby determine a clutch engagement degree corresponding to the calculated drive torque.

[0030] As described above, the ECU 7 is configured to adjust the clutch engagement degree under the condition that the vehicle 1 is maintained in a stopped state. Note that the ECU 7 switches from a first mode to a second mode when it is determined that the accelerator pedal is in an operated state according to the operation amount of the accelerator pedal 14 measured by the accelerator pedal position sensor 15. The first mode adjusts the clutch engagement degree to maintain the stopped state of the vehicle 1, and the second mode adjusts the clutch engagement degree according to the operating conditions of the engine 2 and the changed state of the shift position of the ASG 3.

[0031] Next, a power transmission control task of the power transmission control apparatus of this embodiment configured as above will be described below with reference to Fig. 5. Note that the following power transmission control task is started when the ECU 7 determines that the vehicle 1 is stopped according to the vehicle speed measured by the vehicle speed sensor 16.

[0032] First, in step S1, the ECU 7 determines whether the vehicle 1 is stopped on an uphill surface according to the slope measured by the slope sensor 11. If it is determined that the vehicle 1 is not stopped on an uphill surface, the ECU 7 terminates the power transmission control task.

[0033] When it is determined that the vehicle 1 is stopped on an upward surface, the ECU 7 refers to the required braking torque characteristic curve shown in Fig. 2, to determine the required braking torque according to the inclination of the running surface of the vehicle 1 to the direction of travel. In addition, the ECU 7 refers to the torque correction coefficient characteristic curve shown in Fig. 3, to thereby determine a torque correction coefficient corresponding to an actual vehicle weight measured by the vehicle weight sensor 12. Then, the ECU 7 multiplies the required braking torque by the torque correction coefficient, thereby calculating the required braking torque.

[0034] Next, in step S3, the ECU 7 determines whether the accelerator pedal is in the depressed state according to the depressed amount of the accelerator pedal 14 measured by the accelerator pedal position sensor 15. If it is determined that the accelerator pedal is in the depressed state, the ECU 7 terminates the power transmission control task.

[0035] When it is determined that the accelerator pedal is not in the depressed state, the ECU 7 identifies, in step S4, a braking torque by the braking device 6 according to the depressing amount of the brake pedal 10 measured by the brake position sensor 13.

[0036] Subsequently, in step S5, the ECU 7 determines whether the required braking torque calculated in step S2 is greater than the braking torque by the braking device 6 identified in step S4. If it is determined that the required braking torque is equal to or less than the braking torque by the braking device 6, the ECU 7 returns the power transmission control task to step S3.

[0037] If it is determined in step S5 that the required braking torque is greater than the braking torque by the braking device 6, the ECU 7 subtracts the braking torque by the braking device 6 from the required braking torque in step S6 and thereby calculates the required drive torque that the clutch 4 transmits.

[0038] Next, at step S7, the ECU 7 refers to the drive torque characteristic shown in Fig. 4, and controls the clutch 4 to cause the clutch 4 to transmit the required drive torque calculated in step S6. Thereafter, the ECU 7 returns the power transmission control task to step S3.

[0039] This embodiment described above controls the clutch 4 to cause the clutch 4 to transmit a drive torque in accordance with the braking torque required to maintain the stopped state of the vehicle 1. This therefore prevents the vehicle 1 from slipping downward.

[0040] In particular, this embodiment does not require an actuator for controlling a parking brake or a hill start device for maintaining brake hydraulic pressure. This prevents the vehicle 1 equipped with the ASG 3 from sliding downward without increasing the number of components installed in the vehicle 1.

[0041] In addition, this embodiment controls the clutch 4 to cause the clutch 4 to transmit drive torque further in accordance with a braking torque by a braking device 6. Specifically, this embodiment controls the clutch 4 to cause the clutch 4 to transmit drive torque under the condition that a braking torque required to maintain the stopped state of the vehicle 1 is greater than a braking torque by the braking device 6, wherein the drive torque is represented as subtracting the braking torque by the braking device 6 from the braking torque required to maintain the stopped state of the vehicle 1.

[0042] This embodiment therefore adjusts the clutch engagement degree to cause the clutch 4 to transmit drive torque that supplements the deficiency of the braking torque based on an operation of the brake pedal 10 with respect to the braking torque required to maintain the stopped state of the vehicle 1. This adjustment prevents the downward slide of the vehicle 1 due to an erroneous operation of the brake pedal 10 while the vehicle is stopped and enables the vehicle 1, which is in the stopped state, to start smoothly.

[0043] This embodiment also corrects, according to the actual vehicle weight, a braking torque required to maintain the stopped state of the vehicle 1. This thus prevents the vehicle 1 from sliding downward even when the actual weight varies depending on the weight of the occupant(s) and loads, including transported goods and fuel.

[0044] In this embodiment, it has been described that the ECU 7 corrects a braking torque required to maintain the stopped state of the vehicle 1. However, such correction may be omitted if the weight of the passenger(s) and loads, including transported goods and fuel, are ignored with respect to the horsepower of the vehicle 1. In this case, the actual weight may be represented as a constant on the required braking torque map.

[0045] Furthermore, in this embodiment, it was described that the ECU 7 calculates a required braking torque according to the inclination of the running surface of the vehicle 1 to the traveling direction. However, the ECU 7 may calculate a higher required braking torque by taking into account errors due to various factors. In this case, a higher required braking torque may be set in the required braking torque map.

[0046] An embodiment of the present invention has been disclosed. It is obvious that those skilled in the art can modify the embodiment without departing from the scope of the present invention. All modified or equivalent matter is intended to be encompassed by the following claims. List of reference symbols 1 vehicle 2 Motor (power source) 3 ASG (automated manual transmission) 4 Clutch 6 Braking device 20 Clutch control unit 21 Calculation unit for a required braking torque

Claims

[1] Power transmission control device for a vehicle (1) equipped with an automated manual transmission (3), the power transmission control device comprising: a clutch control unit (20) that controls a clutch (4) for changing a drive torque transmitted from a drive source (2) of the vehicle to the automated manual transmission (3); and a required braking torque calculation unit (21) that calculates, according to an inclination of a running surface of the vehicle (1) to a traveling direction, a required braking torque required to maintain a stopped state of the vehicle (1), wherein the power transmission control device characterized by is that the required braking torque calculation unit (21) calculates the required braking torque under the condition that the vehicle (1) is stopped on an upward surface inclined upward to the direction of travel; under the condition that the vehicle (1) is stopped on the uphill surface, the clutch control unit (20) identifies a braking torque by the braking device (6) of the vehicle (1) under the condition that an accelerator pedal (14) is not in an actuated state, and controls the clutch (4) to cause the clutch (4) to transmit a drive torque according to the required braking torque under the condition that the required braking torque required to maintain the stopped state of the vehicle (1) is greater than the braking torque by the braking device (6), wherein the drive torque according to the required braking torque corresponds to a torque obtained by subtracting the braking torque by the braking device (6) from the required braking torque required to maintain the stopped state of the vehicle (1); and under the condition that the vehicle (1) is stopped on the uphill surface, the clutch control unit (20) controls the clutch (4) according to operating conditions of the drive source (2) and a changed state of a shift position of the automated manual transmission (3) when the accelerator pedal (14) is in an actuated state, instead of controlling the clutch (4) to cause the clutch (4) to transmit the drive torque according to the required braking torque.

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