vehicle

Abstract

To perform downshift of a transmission corresponding to a preference of a driver.SOLUTION: A vehicle includes: a driving source; a transmission for changing speed of power from the driving source and transmitting the power to a driving wheel; and a control device that controls the driving source and the transmission. When a predetermined condition where a second traveling mode of emphasizing acceleration / deceleration performance compared to a first traveling mode is set and an absolute value of average acceleration of the vehicle for a predetermined time is predetermined acceleration or larger is not satisfied, the control device determines whether or not downshift of the transmission is performed on the basis of deceleration of the vehicle. When the predetermined condition is satisfied, the control device determines whether or not the downshift of the transmission is performed on the basis of master cylinder pressure based on a brake operation or brake torque.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a vehicle.

Background Art

[0002] Conventionally, as this type of vehicle, a vehicle equipped with an engine and an automatic transmission that shifts the power from the engine and transmits it to the drive wheels has been proposed (see, for example, Patent Document 1). In this vehicle, when the deceleration of the vehicle exceeds a deceleration determination value, a downshift command is output to the automatic transmission.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] I When determining whether to output a downshift command to the automatic transmission based on the deceleration of the vehicle as in the above-described vehicle, the time delay from when the driver starts the braking operation until the downshift of the automatic transmission is performed may be relatively long. For this reason, there is a possibility that the downshift of the transmission does not conform to the driver's preference. The vehicle of the present disclosure has as its main object to perform a downshift of the transmission according to the driver's preference.

Means for Solving the Problems

[0005] The vehicle of this disclosure employs the following means to achieve the main objective described above. The vehicle of this disclosure comprises a drive source, a transmission that transmits power from the drive source to the drive wheels by shifting the speed, and a control device that controls the drive source and the transmission, wherein the control device determines whether or not to downshift the transmission based on the deceleration of the vehicle when a second driving mode that prioritizes acceleration and deceleration performance compared to a first driving mode is set and a predetermined condition is not met in which the absolute value of the average acceleration of the vehicle over a predetermined time is equal to or greater than a predetermined acceleration, and when the predetermined condition is met, it determines whether or not to downshift the transmission based on the master cylinder pressure or brake torque based on brake operation. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic diagram of the vehicle 20 of this embodiment. [Figure 2] This is a flowchart showing an example of a processing routine. [Figure 3] This is a flowchart showing an example of a processing routine. [Modes for carrying out the invention]

[0007] Embodiments of this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of the vehicle 20 of this embodiment. As shown in the figure, the vehicle 20 of this embodiment includes an engine 22 as a drive source, a power transmission device 24, a brake device 40, and a main electronic control unit (hereinafter referred to as "main ECU") 50.

[0008] The engine 22 is configured as an internal combustion engine that outputs power using gasoline or diesel fuel, and the output shaft (crankshaft) of the engine 22 is connected to the torque converter 25 of the power transmission device 24. The power transmission device 24 has a torque converter 25 and a transmission 26. The torque converter 25 is configured as a general fluid transmission device and transmits the power from the output shaft of the engine 22 to the input shaft of the transmission 26 with or without torque amplification. The transmission 26 is configured as a stepped transmission such as a 4-speed, 5-speed, 6-speed, or 10-speed transmission and has an input shaft, an output shaft, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches and brakes). The output shaft of the transmission 26 is connected to the drive wheels 29a and 29b via a differential gear and axle. The transmission 26 forms multiple forward and reverse gears by engaging and disengaging multiple friction engagement elements.

[0009] The brake system 40 is configured as a hydraulically driven brake system and comprises a master cylinder 41, a plurality of brake pads 42a to 42d, a plurality of brake wheel cylinders, and a brake actuator 44. The master cylinder 41 is pressurized when the brake pedal 65 is pressed. The plurality of brake pads 42a to 42d are mounted on the drive wheels 29a, 29b and the driven wheels 29c, 29d, respectively. The plurality of brake wheel cylinders drive the plurality of brake pads 42a to 42d, respectively. The brake actuator 44 is basically configured to adjust the hydraulic pressure of the plurality of brake wheel cylinders based on the pressure of the master cylinder 41 (master cylinder pressure Pm) in order to apply braking force to the drive wheels 29a, 29b and the driven wheels 29c, 29d. The brake actuator 44 is controlled by an electronic brake control unit (hereinafter referred to as "brake ECU") 48.

[0010] The brake ECU 48 is equipped with a microcomputer (hereinafter referred to as "microcontroller"), which has a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The brake ECU 48 receives input such as the master cylinder pressure Pm, which is the pressure of the master cylinder 41, from the pressure sensor 41a. The brake ECU 48 outputs control signals to the brake actuator 44. The brake ECU 48 is connected to the main ECU 50 via a communication port.

[0011] The main ECU 50, like the brake ECU 48, is equipped with a microcontroller. The main ECU 50 receives signals from various sensors. Signals received by the main ECU 50 include, for example, signals related to the state of the engine 22 from multiple sensors, such as the crank angle θcr of the crankshaft of the engine 22 from the crank angle sensor. Signals related to the state of the power transmission device 24 from multiple sensors, such as the rotational speed Nin, Nout of the input and output shafts of the transmission 26 from the rotational speed sensor. Other signals include the ignition signal from the ignition switch 60 and the shift position SP, which is the operating position of the shift lever 61, from the shift position sensor 62. Other signals include the accelerator opening Acc, which is the amount of depression of the accelerator pedal 63, from the accelerator direction sensor 64, and the brake pedal depression BP, which is the amount of depression of the brake pedal 65, from the brake position sensor 66. Other examples of signals include the vehicle speed V from the vehicle speed sensor 67, the longitudinal acceleration Gx and lateral acceleration Gy from the acceleration sensor 68, and the steering angle θw from the steering angle sensor 69. The driving mode from the mode switch 70 can also be mentioned. Driving modes include, for example, a normal mode (first driving mode), a sport mode (second driving mode) that prioritizes acceleration and deceleration performance compared to the normal mode, and an eco mode that prioritizes fuel efficiency compared to the normal mode and sport mode. The main ECU 50 outputs various control signals. Signals output by the main ECU 50 include, for example, control signals to the engine 22 and the power transmission device 24. The main ECU 50 calculates the rotational speed Ne of the engine 22 based on the crank angle θcr, and calculates the average longitudinal acceleration Gxav and average lateral acceleration Gyav, which are the average values ​​of the longitudinal acceleration Gx and lateral acceleration Gy over a predetermined time.

[0012] In the vehicle 20 of this embodiment, the main ECU 50 basically sets a target gear position Gs* for the transmission 26 based on the driving mode, accelerator opening Acc, brake pedal depression BP, and vehicle speed V, and controls the transmission 26 so that the gear position Gs of the transmission 26 becomes the target gear position Gs*. In addition, it sets a target torque Te* for the engine 22 based on the driving mode, accelerator opening Acc, vehicle speed V, and the gear position Gs of the transmission 26, and controls the engine 22 so that the engine 22 is driven according to the target torque Te*.

[0013] Next, the operation of the vehicle 20 in this embodiment will be described, in particular, the operation from when the driver presses the brake pedal 65 (from the start of pressing) until the transmission 26 downshifts. Figure 2 is a flowchart showing an example of a processing routine that is repeatedly executed by the main ECU 50 during this period.

[0014] When the processing routine in Figure 2 is executed, the main ECU 50 determines whether the driving mode is sport mode (step S100) and whether the absolute value of the average longitudinal acceleration Gxav is greater than or equal to the threshold Gxref (step S110). The threshold Gxref is used to determine whether the driver is in an acceleration / deceleration orientation. If it is determined that the driving mode is not sport mode or that the absolute value of the average longitudinal acceleration Gxav is less than the threshold Gxref, it is determined whether the vehicle's deceleration Dv is greater than or equal to the threshold Dvref (step S120). The vehicle's deceleration Dv can be calculated, for example, by annealing the value of the rate of change of vehicle speed V per unit time (vehicle speed change rate) and then inverting the sign of the result. The threshold Dvref is used to determine whether the vehicle is decelerating to some extent. If it is determined that the vehicle's deceleration Dv is less than the threshold Dvref, this routine is terminated.

[0015] If it is determined in step S120 that the vehicle's deceleration Dv is greater than or equal to the threshold Dvref, the target gear position Gs* is set (step S130). The target gear position Gs* can be set, for example, based on at least one of the following: deceleration Dv, brake pedal pressure BP, master cylinder pressure Pm, and vehicle speed V. Next, it is determined whether the target gear position Gs* is less than the current gear position Gs (step S140), and if it is determined that the target gear position Gs* is not less than the current gear position Gs, this routine is terminated.

[0016] If it is determined in step S140 that the target gear position Gs* is less than the current gear position Gs, it is determined whether the absolute value of the lateral acceleration Gy is less than or equal to the threshold Gyref1 (step S150). The threshold Gyref1 is used to determine whether the vehicle is moving nearly straight or turning. If it is determined that the absolute value of the lateral acceleration Gy is less than or equal to the threshold Gyref1, the transmission 26 is downshifted (step S160) and this routine is terminated. On the other hand, if it is determined that the absolute value of the lateral acceleration Gy is greater than the threshold Gyref1, this routine is terminated without downshifting the transmission 26. This avoids downshifting the transmission 26 while the vehicle is turning.

[0017] If it is determined in step S100 that the driving mode is sport mode and in step S110 that the absolute value of the average longitudinal acceleration Gxav is greater than or equal to the threshold Gxref, then it is determined whether the master cylinder pressure Pm is greater than or equal to the threshold Pmref (step S170). The threshold Pmref is used to determine whether the brake pedal 65 has been pressed to a certain extent by the driver. If the master cylinder pressure Pm is less than the threshold Pmref, this routine is terminated.

[0018] If it is determined in step S170 that the master cylinder pressure Pm is greater than or equal to the threshold Pmref, the target gear position Gs* is set (step S180) in the same way as in step S130, and it is determined whether the target gear position Gs* is less than the current gear position Gs (step S190). If it is determined that the target gear position Gs* is not less than the current gear position Gs, this routine is terminated.

[0019] If it is determined in step S190 that the target gear position Gs* is less than the current gear position Gs, it is determined whether the absolute value of the lateral acceleration Gy is less than or equal to threshold Gyref2, which is smaller than threshold Gyref1 (step S200). Threshold Gyref2 is used, like threshold Gyref, to determine whether the vehicle is moving in a nearly straight line or turning. If it is determined that the absolute value of the lateral acceleration Gy is less than or equal to threshold Gyref2, the transmission 26 is downshifted (step S210) and this routine is terminated. On the other hand, if it is determined that the absolute value of the lateral acceleration Gy is greater than threshold Gyref2, this routine is terminated without downshifting the transmission 26. This avoids downshifting the transmission 26 while the vehicle is turning.

[0020] Consider a situation where when the driver enters a curve from a straight road, the driver steps on the brake pedal 65 to decelerate the vehicle 20 and downshift the transmission 26. When the driver steps on the brake pedal 65, the master cylinder pressure Pm increases, the braking torque of the vehicle increases, and the vehicle decelerates. Therefore, when using the master cylinder pressure Pm, although the determination of whether to downshift the transmission 26 can be started earlier than when using the vehicle deceleration Dv, there is a risk of overly sensitive downshifting of the transmission 26 in response to the driver's operation of the brake pedal 65. Taking this into account, in this embodiment, when the vehicle is in sports mode and a predetermined condition that the absolute value of the average longitudinal acceleration Gxav is less than the threshold value Gxref is not satisfied, it is determined whether to downshift the transmission 26 when the vehicle deceleration Dv is greater than or equal to the threshold value Dvref, and when the predetermined condition is satisfied, it is determined whether to downshift the transmission 26 when the master cylinder pressure Pm is greater than or equal to the threshold value Pmref. Thereby, when the predetermined condition is not satisfied, it is possible to suppress overly sensitive downshifting of the transmission 26, and when the predetermined condition is satisfied, it is possible to suppress the downshift of the transmission 26 from trailing into the curve. As a result, it is possible to perform a downshift of the transmission 26 according to the driver's preference. Also, taking this into account, the threshold value Gyref2 is set to a value smaller than the threshold value Gyref1.

[0021] In the vehicle 20 of this embodiment described above, when the vehicle is in sports mode and a predetermined condition that the absolute value of the average longitudinal acceleration Gxav is less than the threshold value Gxref is not satisfied, it is determined whether to downshift the transmission 26 when the vehicle deceleration Dv is greater than or equal to the threshold value Dvref, and when the predetermined condition is satisfied, it is determined whether to downshift the transmission 26 when the master cylinder pressure Pm is greater than or equal to the threshold value Pmref. Thereby, it is possible to perform a downshift of the transmission 26 according to the driver's preference.

[0022] In the above-described embodiment, the main ECU 50 executes the processing routine of FIG. 2, but instead, it may execute the processing routine of FIG. 3. The processing routine of FIG. 3 is different in that the processing of steps S180 to S210 is replaced with the processing of steps S300 to S400. Therefore, the same step numbers are assigned to the same processing as the processing routine of FIG. 2 in the processing routine of FIG. 3, and detailed description thereof is omitted.

[0023] In the processing routine of FIG. 3, when the main ECU 50 determines at step S170 that the master cylinder pressure Pm is equal to or higher than the threshold value Pmref, it determines whether or not the engine speed Neb at the time of brake-on, which is the engine speed Ne when the brake pedal 65 is depressed (when the brake is on), is equal to or higher than the threshold value Nebref (step S300). The threshold value Nebref is used to determine whether or not the brake pedal 65 has been depressed during rapid acceleration. Since the absolute value of the average longitudinal acceleration Gxav is used in step S110, the absolute value of the average longitudinal acceleration Gxav may continue to be equal to or higher than the threshold value Gxref even after the end of rapid acceleration. In view of this, it is determined whether or not the brake pedal 65 has been depressed during rapid acceleration by using the engine speed Neb at the time of brake-on.

[0024] When it is determined at step S300 that the engine speed Neb at the time of brake-on is equal to or higher than the threshold value Nebref, it is determined whether or not the vehicle speed V is less than the threshold value Vref1(Gs) (step S310). The threshold value Vref1(Gs) is a threshold value used to determine whether or not over-rotation of the engine 22 can be restricted (prevented) even when the transmission 26 is downshifted, and is determined for each gear stage Gs of the transmission 26. When it is determined that the vehicle speed V is equal to or higher than the threshold value Vref1(Gs), this routine ends without downshifting the transmission 26. Thereby, over-rotation of the engine 22 can be restricted. On the other hand, when it is determined that the vehicle speed V is less than the threshold value Vref1(Gs), the same processing as the processing of steps S180 to S210 is executed (steps S320 to S350), and this routine ends.

[0025] If it is determined in step S300 that the rotational speed Neb when the brake is applied is less than the threshold Nebref, it is determined whether the vehicle speed V is less than a threshold Vref2(Gs) which is lower than the threshold Vref1(Gs) (step S360). The threshold Vref2(Gs) is used to determine whether the rotational speed Ne of the engine 22 will remain below the threshold Nebref even if the transmission 26 is downshifted, and is defined for each gear position Gs of the transmission 26. If it is determined that the vehicle speed V is greater than or equal to the threshold Vref2(Gs), this routine is terminated without downshifting the transmission 26. On the other hand, if it is determined that the vehicle speed V is less than the threshold Vref2(Gs), the same processing as in steps S180 to S210 is performed (steps S370 to S400), and this routine is terminated.

[0026] In the embodiments described above, the absolute value of the average longitudinal acceleration Gxav was used in the processing routines of Figures 2 and 3 in step S110. However, the absolute value of the average lateral acceleration Gyav may also be used, or the absolute value of the average acceleration GxGyav including longitudinal, lateral, and vertical acceleration may also be used. Doing so can suppress the oversensitivity of the system in determining that the driver is acceleration-or-deceleration oriented, for example, when the driver is driving on a highway where the absolute value of the longitudinal acceleration is relatively large. Also, although the master cylinder pressure Pm was used in step S170, the brake torque applied to the vehicle may be used instead. The brake torque can be obtained, for example, by conversion from the master cylinder pressure. Although the absolute value of the lateral acceleration Gy was used in steps S150, S200, S340, and S390, the absolute value of the longitudinal acceleration Gx may also be used, or the steering angle θw may be used instead.

[0027] In the embodiment described above, the vehicle 20 uses a stepped transmission 26, but a continuously variable transmission may also be used. Also, although an engine 22 is used as the drive source, a motor may be used instead or in addition to it.

[0028] While embodiments for implementing this disclosure have been described above, this disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0029] This disclosure can be used in industries such as vehicle manufacturing. [Explanation of Symbols]

[0030] 20 Vehicle, 22 Engine, 26 Transmission, 41 Master Cylinder, 50 Main ECU, 65 Brake Pedal, 70 Mode Switch.

Claims

[Claim 1] A vehicle comprising a drive source, a transmission that changes the speed of the power from the drive source and transmits it to the drive wheels, and a control device that controls the drive source and the transmission, The control device determines whether or not to downshift the transmission based on the vehicle's deceleration when a second driving mode that prioritizes acceleration and deceleration performance compared to the first driving mode is set and a predetermined condition is not met in which the absolute value of the vehicle's average acceleration over a predetermined period of time is equal to or greater than a predetermined acceleration; and when the predetermined condition is met, it determines whether or not to downshift the transmission based on the master cylinder pressure or brake torque based on the brake operation. vehicle.

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