vehicle

Abstract

To restrain drivability from being deteriorated.SOLUTION: A vehicle comprises a driving source, a transmission which transmits to driving wheels by shifting power from the driving source and a control device which controls the driving source and the transmission. The control device executes down-shift delay processing which changes timing of down-shift of the transmission on low vehicle speed side in comparison with when prescribed condition is not satisfied when there is satisfied the prescribed condition which is in follow-up mode at which an own vehicle follows up a front vehicle and overtaking of the front vehicle is restricted and is at accelerator-off and brake-off.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to vehicles. [Background technology]

[0002] Conventionally, a vehicle of this type has been proposed that includes a drive unit that outputs drive force for driving and a brake unit that applies braking force to the vehicle (see, for example, Patent Document 1). This vehicle performs cruise control by using modes including a solo cruise mode that controls the drive unit to travel at a set speed when there is no preceding vehicle within a first predetermined distance, a follow cruise mode that controls the drive unit and brake unit to follow the preceding vehicle within a set speed range at a distance of at least a second predetermined distance when there is a preceding vehicle within the first predetermined distance, and a stop transition mode that controls the drive unit and brake unit to stop the preceding vehicle at a distance of a third predetermined distance when it is predicted that the preceding vehicle will stop. During travel in the stop transition mode, the vehicle notifies the driver of a planned stopping position of the vehicle when the vehicle's speed is faster than that of the preceding vehicle, and stops notifying the driver of the planned stopping position of the vehicle when the vehicle's speed is slower than that of the preceding vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-27997 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle equipped with a drive source and a transmission that changes the speed of power from the drive source and transmits it to the drive wheels, when the vehicle is in a following mode in which it follows a vehicle in front, overtaking of the vehicle in front is restricted, and the accelerator and brake are off, if a relatively large change in deceleration acceleration (deceleration G) occurs due to a relatively large change in the rotation speed of the drive source caused by a downshift of the transmission as the vehicle decelerates, this may lead to a deterioration in drivability.

[0005] The vehicle of the present disclosure has a primary objective of suppressing deterioration in drivability. [Means for solving the problem]

[0006] The vehicle of the present disclosure employs the following means to achieve the above-mentioned main object.

[0007] The vehicle of the present disclosure includes: A vehicle including a drive source, a transmission that changes the speed of power from the drive source and transmits it to drive wheels, and a control device that controls the drive source and the transmission, When predetermined conditions are met, that is, when the host vehicle is in a following mode in which the host vehicle follows a preceding vehicle, overtaking of the preceding vehicle is restricted, and the accelerator and brake are released, the control device executes a downshift delay process to change the timing of downshifting of the transmission to a lower vehicle speed side compared to when the predetermined conditions are not met. The gist of this is as follows.

[0008] In the vehicle disclosed herein, when predetermined conditions are met, such as the host vehicle being in a following mode in which it follows a vehicle ahead, overtaking of the vehicle ahead is restricted, and the accelerator and brakes are off, a downshift delay process is executed to change the timing of a downshift of the transmission to a lower vehicle speed compared to when the predetermined conditions are not met. This delays the downshift of the transmission, thereby suppressing changes in the rotation speed of the drive source when the transmission downshifts, and suppressing changes in deceleration acceleration (deceleration G) of the host vehicle. As a result, deterioration of drivability can be suppressed.

[0009] In the vehicle of the present disclosure, the control device may determine that overtaking of the vehicle in front is restricted when there is one lane on each side, or when there are surrounding vehicles within a predetermined distance in the left and right lanes of the vehicle.

[0010] In the vehicle of the present disclosure, the control device may perform the downshift delay process by changing the shift line of the transmission to a lower vehicle speed when the accelerator and brake are released, and may perform the downshift delay process by downshifting the transmission when the rotation speed of the drive source reaches or exceeds a predetermined rotation speed.

[0011] In the vehicle disclosed herein, when the forward vehicle disengages and a request for acceleration of the host vehicle is made while the downshift delay process is being performed, the control device may increase the torque of the drive source so as to compensate for at least a portion of the shortfall in the torque output to the drive wheels when the downshift delay process is being performed relative to the torque output to the drive wheels when the downshift delay process is not being performed. This makes it possible to compensate for at least a portion of the shortfall in the torque output to the drive wheels while the downshift delay process is being performed. As a result, insufficient acceleration of the host vehicle during the downshift delay process can be suppressed, and a feeling of sluggishness or the like that the driver feels can be suppressed.

[0012] In this case, when the vehicle ahead leaves while the downshift delay process is being executed and a request to accelerate the vehicle is made, the control device may change the gear position of the transmission and then terminate the downshift delay process.

[0013] In the vehicle of the present disclosure, the control device may terminate the downshift delay processing when, during execution of the downshift delay processing, no acceleration request is made for the vehicle for a predetermined period of time after the preceding vehicle has left. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic configuration diagram of a vehicle 20 according to the present embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of a shift line diagram. [Figure 3] 10 is a flowchart illustrating an example of a processing routine. [Figure 4] FIG. 10 is an explanatory diagram showing an example of a shift line map for downshift delay processing. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of a vehicle 20 according to this embodiment. As shown in the figure, the vehicle 20 according to this embodiment includes an engine 22 as a drive source, a power transmission device 24, a braking device 40, a navigation device 80, and a main electronic control unit (hereinafter referred to as "main ECU") 50.

[0016] The engine 22 is configured as a multiple-cylinder internal combustion engine that outputs power using gasoline, diesel, etc. as fuel. An output shaft (crankshaft) of the engine 22 is connected to a torque converter 25 of the power transmission device 24.

[0017] The power transmission device 24 includes a torque converter 25 and a transmission 26. The torque converter 25 is configured as a typical fluid transmission and includes a pump impeller connected to the output shaft of the engine 22, a turbine runner connected to the input shaft of the transmission 26, a stator that regulates the flow of hydraulic oil from the turbine runner to the pump impeller, a one-way clutch that restricts the rotation direction of the stator to one direction, and a hydraulically driven lock-up clutch that connects and disconnects the pump impeller and turbine runner. The torque converter 25 transmits 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 five-speed stepped transmission and includes an input shaft, an output shaft, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches and brakes). The input shaft of the transmission 26 is connected to the torque converter 25. An output shaft of the transmission 26 is connected to drive wheels 29a, 29b via a differential gear and an axle. The transmission 26 provides a plurality of forward and reverse gears by engaging and disengaging a plurality of friction engagement elements.

[0018] The brake device 40 is configured as a hydraulically driven brake device and includes a master cylinder 41, multiple brake pads 42a to 42d, multiple brake wheel cylinders, and a brake actuator 44. The master cylinder 41 is pressurized when a brake pedal 65 is depressed. The multiple brake pads 42a to 42d are attached to the drive wheels 29a, 29b and the driven wheels 29c, 29d, respectively. The multiple brake wheel cylinders drive the multiple brake pads 42a to 42d, respectively. The brake actuator 44 is configured to adjust the hydraulic pressure of the multiple brake wheel cylinders to apply braking force to the drive wheels 29a, 29b and the driven wheels 29c, 29d. For example, the brake actuator 44 adjusts the hydraulic pressure of the multiple brake wheel cylinders so that the braking force based on the pressure (master cylinder pressure Pm) of the master cylinder 41 generated in response to depression of the brake pedal 65 acts on the driving wheels 29a, 29b and the driven wheels 29c, 29d, or adjusts the hydraulic pressure of the multiple brake wheel cylinders so that the braking force required of the braking device 40 acts on the driving wheels 29a, 29b and the driven wheels 29c, 29d, regardless of depression of the brake pedal 65, for example, when the vehicle approaches a vehicle ahead.

[0019] The navigation device 80 includes a main body with a built-in control unit, a GPS, and a display. The control unit has a storage medium (e.g., a hard disk or SSD) storing map information and the like, an input / output port, and a communication port. The map information includes service information (e.g., tourist information, parking lots, etc.) and road information for each driving section (e.g., between traffic lights and between intersections) stored as a database. The road information includes distance information, road width information, number of lanes information, area information (urban or suburban), road type information (general road or expressway), gradient information, legal speed limit, number of traffic lights, turning radius of each curve, etc. The GPS detects the vehicle's position based on signals transmitted from multiple GPS satellites. The display is configured as a touch panel type display that displays various information such as the vehicle's current position and the driving route to the destination, and also allows the user to input various instructions. When a user operates the display to set a destination, the navigation device 80 sets a driving route to the destination based on map information stored in a storage medium, the current position of the vehicle detected by GPS, and the set destination, and displays the set driving route on the display to provide route guidance. The navigation device 80 communicates with the main ECU 50.

[0020] The main ECU 50 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. The main ECU 50 receives signals from various sensors. Examples of signals received by the main ECU 50 include signals related to the state of the engine 22 from multiple sensors, such as a crank angle θcr of the crankshaft of the engine 22 from a crank angle sensor. Other examples include signals related to the state of the power transmission device 24 from multiple sensors, such as rotation speeds Nin and Nout of the input and output shafts of the transmission 26 from a rotation speed sensor. Other examples include a master cylinder pressure Pm, which is the pressure in the master cylinder 41, from a pressure sensor 41a. Other examples include an ignition signal from an ignition switch 60 and a shift position SP, which is the operating position of the shift lever 61, from a shift position sensor 62. Other examples include an accelerator opening Acc, which is the depression amount of the accelerator pedal 63, from an accelerator pedal position sensor 64, and a brake pedal position BP, which is the depression amount of the brake pedal 65, from a brake pedal position sensor 66. Other examples of information that can be included include the vehicle speed V from the vehicle speed sensor 67, the longitudinal acceleration Gx and lateral acceleration Gy, which are accelerations of the host vehicle in the longitudinal and lateral directions, from the acceleration sensor 68, and the steering angle θw from the steering angle sensor 69. Other examples of information about the host vehicle and its surroundings from the periphery recognition device 70 include the inter-vehicle distance and relative speed between the host vehicle and a vehicle ahead, the inter-vehicle distance and relative speed between the host vehicle and a vehicle behind, and the distance between vehicles to the sides (including the left and right front) of the host vehicle. The periphery recognition device 70 is configured to include at least some of a camera, millimeter wave radar, quasi-millimeter wave radar, infrared laser radar, sonar, etc.

[0021] The main ECU 50 outputs various control signals. Examples of signals output by the main ECU 50 include a control signal to the engine 22, a control signal to the power transmission device 24, and a control signal to the brake actuator 44. The main ECU 50 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr from the crank angle sensor. The main ECU 50 communicates with the navigation device 80. The main ECU 50 performs brake control for the driving assistance system, such as collision mitigation brake control.

[0022] In the vehicle 20 of this embodiment, the main ECU 50 sets a target gear Gs* for the transmission 26 based on the accelerator pedal position Acc, the vehicle speed V, and a shift map, and controls the transmission 26 so that the gear Gs of the transmission 26 becomes the target gear Gs*. The main ECU 50 also sets a target torque Te* for the engine 22 based on the accelerator pedal position Acc, the vehicle speed V, and the gear Gs of the transmission 26, and controls the engine 22 so that the engine 22 operates based on the target torque Te*. FIG. 2 is an explanatory diagram showing an example of a shift map. For simplicity, in the example of FIG. 2, the shift line for upshifting (upshift line) and the shift line for downshifting (downshift line) of the transmission 26 are the same. Note that the upshift line and the downshift line may be different.

[0023] Next, a description will be given of the operation of the vehicle 20 of this embodiment. Fig. 3 is a flowchart showing an example of a processing routine executed by the main ECU 50. This routine is executed repeatedly.

[0024] When the processing routine of Figure 3 is executed, the main ECU 50 determines whether the vehicle is in a following mode in which it follows a vehicle ahead (step S100), determines whether an overtaking restriction condition that restricts overtaking of the vehicle ahead is met (step S110), and determines whether the accelerator and brake are off (step S120).

[0025] The process of determining whether the vehicle is in the follow-up mode can be performed using information from the surroundings recognition device 70, such as the inter-vehicle distance and relative speed between the host vehicle and the preceding vehicle. For example, the vehicle is determined to be in the follow-up mode when the preceding vehicle is present within a predetermined distance L1 ahead of the host vehicle. The predetermined distance L1 may be a fixed value or may be set based on the relative speed between the host vehicle and the preceding vehicle.

[0026] The overtaking restriction condition is an OR condition of a lane number condition that there is one lane in each direction and a side vehicle condition that a surrounding vehicle exists within a predetermined distance in the left and right lanes of the host vehicle. The process of determining whether the lane number condition is met can be performed using information from the navigation device 80, such as the current position of the host vehicle and road information (lane number information). The process of determining whether the surrounding vehicle condition is met can be performed using information from the surrounding recognition device 70, such as the distance between the host vehicle and a vehicle on the side (including the left and right front) of the host vehicle.

[0027] The process of determining whether the accelerator and brake are both off can be performed using the accelerator opening Acc from the accelerator pedal position sensor 64 and the brake pedal position BP from the brake pedal position sensor 66.

[0028] This routine is terminated when it is determined in step S100 that the vehicle is not in follow-up mode, when it is determined in step S110 that the overtaking restriction conditions are not met (neither the lane number condition nor the side vehicle condition is met), or when it is determined in step S120 that the accelerator or brake is on.

[0029] If it is determined in step S100 that the vehicle is in follow mode, and if it is determined in step S110 that the overtaking restriction condition is met (the lane number condition or the side vehicle condition is met), and if it is determined in step S120 that the accelerator and brake are both off, then downshift delay processing is started (step S130).

[0030] Here, in the downshift delay process, the shift line map is changed from the normal shift line map to a shift line map for the downshift delay process. FIG. 4 is an explanatory diagram showing an example of a shift line map for the downshift delay process. For comparison, FIG. 4 shows the normal shift line map (the same as FIG. 2) with a dotted line. In the shift line map for the downshift delay process, the shift line of the transmission 26 when the accelerator and brake are off is changed to a lower vehicle speed side compared to the normal shift line map. Since the accelerator and brake are off, the downshift of the transmission 26 is delayed by the downshift delay process, thereby suppressing changes in the rotation speed of the engine 22 and the torque converter 25 when the transmission 26 downshifts, and suppressing changes in deceleration acceleration (deceleration G) of the host vehicle. As a result, deterioration in drivability can be suppressed. In addition, there are cases where the downshift of the transmission 26 itself can be suppressed. It is also possible to prevent inconveniences caused by large changes in deceleration G when driving assistance brake control, such as collision damage mitigation brake control, is being performed.

[0031] When the downshift delay process is started in this manner, it is determined whether the vehicle ahead has left the lane (step S140), and if it is determined that the vehicle ahead has not left the lane, the process waits for the vehicle ahead to leave the lane. Here, the process of determining whether the vehicle ahead has left the lane can be performed using information from the surroundings recognition device 70, such as the inter-vehicle distance and relative speed between the host vehicle and the vehicle ahead. For example, it is determined that the vehicle ahead has left the lane when the vehicle ahead accelerates or changes lanes and is no longer present within a predetermined distance ahead of the host vehicle, or when the host vehicle changes lanes and is no longer present within a predetermined distance ahead of the host vehicle.

[0032] If it is determined in step S140 that the preceding vehicle has left, it is determined whether or not an acceleration request for the host vehicle has been made (step S150). This determination process can be performed by determining whether or not the accelerator pedal opening Acc from the accelerator pedal position sensor 64 is equal to or greater than a threshold Aref.

[0033] If it is determined in step S150 that an acceleration request for the host vehicle has been made, a correction request for the target torque Te* of the engine 22 is made (step S160). When the downshift delay process is being performed, the downshift of the transmission 26 is delayed (suppressed) compared to when the downshift delay process is not being performed. Therefore, when the downshift delay process is being performed, the gear Gs of the transmission 26 may be set to a gear on the higher vehicle speed side compared to when the downshift delay process is not being performed. When a certain torque is being output from the engine 22, the higher the gear Gs of the transmission 26 is (the smaller the gear ratio γ corresponding to the gear Gs is), the smaller the torque output to the drive wheels 29a, 29b. Therefore, when the downshift delay process is being performed, the acceleration of the host vehicle may be insufficient compared to when the downshift delay process is not being performed, which may cause the driver to feel sluggishness. In light of this, in this embodiment, when a correction request for the target torque Te* is made, an increasing correction is made to the target torque Te* of the engine 22 so as to compensate for at least a part of the shortfall in the torque output to the drive wheels 29a, 29b when the downshift delay process is being performed relative to the torque output to the drive wheels 29a, 29b when the downshift delay process is not being performed. This makes it possible to prevent insufficient acceleration of the vehicle while the downshift delay process is being performed, and to prevent the driver from feeling sluggishness or the like.

[0034] Next, it is determined whether the gear position Gs of the transmission 26 has been changed (step S170), and if it is determined that the gear position Gs of the transmission 26 has not been changed, the process returns to step S150. Since a time when an acceleration request for the host vehicle is being made is considered, examples of times when the gear position Gs of the transmission 26 is changed include when the accelerator opening Acc increases and the gear position Gs is downshifted (during so-called kickdown), and when the vehicle speed V increases and the gear position Gs is upshifted.

[0035] If it is determined in step S170 that the gear position Gs of the transmission 26 has been changed, the downshift delay process is ended (step S190) and this routine is ended, thereby changing the shift line map from the shift line map for downshift delay process to the normal shift line map.

[0036] If it is determined in step S150 that no acceleration request has been made for the vehicle, it is determined whether or not no acceleration request has been made for the vehicle for a predetermined time (step S180), and if it is determined that the predetermined time has not yet elapsed, the process returns to step S150.

[0037] If it is determined in step S180 that no acceleration request has been made for the host vehicle for a predetermined period of time, the downshift delay process is terminated (step S190), and the routine is terminated. In this embodiment, taking into consideration that when traveling on a highway, the host vehicle may decelerate and then accelerate to overtake a vehicle while changing lanes, the downshift delay process is terminated before an acceleration request is made for the host vehicle.

[0038] In the vehicle 20 of the present embodiment described above, when predetermined conditions are met, that is, when the vehicle is in a following mode in which it follows a preceding vehicle, overtaking of the preceding vehicle is restricted, and the accelerator and brake are off, the timing of downshifting of the transmission 26 is changed to a lower vehicle speed compared to when the predetermined conditions are not met. Specifically, a downshift delay process is executed to change the shift line of the transmission 26 when the accelerator and brake are off to a lower vehicle speed. This delays the downshift of the transmission 26, thereby suppressing changes in the rotation speed of the engine 22 and the torque converter 25 when the transmission 26 is downshifted, and suppressing changes in the deceleration acceleration (deceleration G) of the vehicle. As a result, deterioration of drivability can be suppressed.

[0039] Furthermore, in the vehicle 20 of this embodiment, when a preceding vehicle leaves while the downshift delay process is being executed and a request for acceleration of the host vehicle is made, the target torque Te* of the engine 22 is increased and corrected to control the engine 22 so as to compensate for at least a portion of the shortfall in the torque output to the drive wheels 29a, 29b when the downshift delay process is being executed relative to the torque output to the drive wheels 29a, 29b when the downshift delay process is not being executed. This prevents the host vehicle from experiencing insufficient acceleration while the downshift delay process is being executed, thereby preventing the driver from feeling sluggish or the like.

[0040] In the above-described embodiment, the downshift delay process is performed by changing the shift line of the transmission 26 to a lower vehicle speed when the accelerator and brakes are both released. However, instead of or in addition to this, the downshift of the transmission 26 may be delayed until the rotation speed Ne of the engine 22 becomes equal to or less than a threshold value Neref. The threshold value Neref is set as a relatively low rotation speed within a range in which noise, vibration, and engine stalling of the engine 22 can be suppressed.

[0041] In the above-described embodiment, when a preceding vehicle leaves the vehicle while the downshift delay process is being performed and a request for acceleration of the host vehicle is made, the target torque Te* of the engine 22 is corrected and increased to control the engine 22 so as to compensate for at least a portion of the shortfall in the torque output to the drive wheels 29 a, 29 b when the downshift delay process is being performed relative to the torque output to the drive wheels 29 a, 29 b when the downshift delay process is not being performed. However, such an increase in the target torque Te* of the engine 22 may not be corrected.

[0042] In the above-described embodiment, the downshift delay process is terminated when the preceding vehicle disengages while the downshift delay process is being executed, a request for acceleration of the host vehicle is made, and the gear position Gs of the transmission 26 is changed, or when no request for acceleration of the host vehicle is made for a predetermined period of time. However, in addition to these, the downshift delay process may also be terminated when the brakes are applied.

[0043] In the above-described embodiment, a five-speed variable transmission is used as the transmission 26. However, instead of this, a four-speed, six-speed, ten-speed, or other variable transmission may be used.

[0044] In the above-described embodiment, the engine 22 is used as the drive source. However, instead of or in addition to this, a motor may be used.

[0045] The following describes the relationship between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section. In the embodiment, the engine 22 corresponds to the "drive source," the transmission 26 corresponds to the "transmission," and the main ECU 50 corresponds to the "control device."

[0046] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0047] The above describes embodiments for implementing the present disclosure, but the present disclosure is not limited to these embodiments and can, of course, be implemented in various forms within the scope of the gist of the present disclosure. [Industrial Applicability]

[0048] The present disclosure is applicable to the vehicle manufacturing industry and the like. [Explanation of symbols]

[0049] 20 vehicle, 22 engine, 24 power transmission device, 25 torque converter, 26 transmission, 29a, 29b drive wheels, 29c, 29d driven wheels, 40 brake device, 41 master cylinder, 41a pressure sensor, 42a to 42d brake pads, 44 brake actuator, 50 main ECU, 60 ignition switch, 61 shift lever, 62 shift position sensor, 63 accelerator pedal, 64 acceleration sensor, 65 brake pedal, 66 brake position sensor, 67 vehicle speed sensor, 68 acceleration sensor, 69 steering angle sensor, 70 surrounding recognition device, 80 navigation device.

Claims

1. A vehicle including a drive source, a transmission that changes the speed of power from the drive source and transmits it to drive wheels, and a control device that controls the drive source and the transmission, When predetermined conditions are met, that is, when the host vehicle is in a following mode in which the host vehicle follows a preceding vehicle, overtaking of the preceding vehicle is restricted, and the accelerator and brake are released, the control device executes a downshift delay process to change the timing of downshifting of the transmission to a lower vehicle speed side compared to when the predetermined conditions are not met. vehicle.

2. 2. The vehicle according to claim 1, The control device determines that overtaking of the preceding vehicle is restricted when there is one lane in each direction or when a surrounding vehicle is present within a predetermined distance in the left or right lane of the host vehicle. vehicle.

3. 3. The vehicle according to claim 1 or 2, The control device changes the shift line of the transmission to a lower vehicle speed side when an accelerator pedal and a brake pedal are released as the downshift delay processing. vehicle.

4. 3. The vehicle according to claim 1 or 2, When the preceding vehicle leaves the vehicle and a request for acceleration of the host vehicle is made while the downshift delay process is being executed, the control device increases and corrects the torque of the drive source so as to compensate for at least a portion of the shortage of torque output to the drive wheels when the downshift delay process is being executed relative to the torque output to the drive wheels when the downshift delay process is not being executed. vehicle.

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