Running control system of vehicle

Abstract

To prevent rotation speed of an engine from abruptly changing when a clutch is connected after speed change operation is performed during running using an ACC function in an MT vehicle.SOLUTION: A running control system of an MT vehicle which is equipped with a manual transmission, a clutch and an ACC controller comprises target gear stage determining means that determines a target gear stage of the transmission in accordance with a running state of the vehicle running using an ACC function, which is configured to perform idling torque control of controlling torque of the engine so that the torque becomes equal to idling torque when the clutch is released during operation of the ACC function, and subsequently perform target gear stage torque control of adjusting required torque so that the rotation speed of the engine corresponds to the target gear stage.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle cruise control system, and more particularly to a cruise control system for a manual transmission vehicle. [Background technology]

[0002] Adaptive cruise control (ACC) is a well-known driving assistance function for vehicles. ACC is a driving control function that drives the vehicle at a constant speed when there is no preceding vehicle ahead, and follows the preceding vehicle while maintaining a set time interval when there is a preceding vehicle ahead that is traveling slower than the set speed. ACC is used not only in automatic transmission vehicles but also in manual transmission vehicles (MT vehicles).

[0003] For example, Patent Document 1 discloses that in order to prevent an increase in engine speed when the driver depresses the clutch pedal to change gears during inter-vehicle distance control, the engine speed obtained by shifting up one gear from the previous state is set as a target speed, and the engine speed is controlled to match this target speed.

[0004] However, in Patent Document 1, if a downshift is performed during acceleration using the ACC function, when the clutch is engaged, the power transmission state is established at the gear stage after the shift operation. Therefore, unless the driver adjusts the engine speed by operating the accelerator pedal while the power is cut off, a sudden change in engine speed occurs, resulting in a problem of shift shock. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-189890 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above-described circumstances, and its purpose is to prevent a sudden change in engine speed when the clutch is engaged after a gear shift operation while driving a manual transmission vehicle using the ACC function, thereby suppressing gear shift shock while taking fuel economy into consideration. [Means for solving the problem]

[0007] In order to solve the above problems, a vehicle driving control system according to the present invention comprises: A manual transmission and a clutch that releasably transmits engine torque to the transmission; an ACC controller that controls the speed of the vehicle to perform an ACC function of maintaining a set vehicle speed when there is no preceding vehicle, and maintaining a set inter-vehicle time when there is a preceding vehicle traveling at a speed slower than the set vehicle speed; a target gear position determination means for determining a target gear position of the transmission in accordance with a running state of the vehicle while the vehicle is running using the ACC function, When the clutch is released during operation of the ACC function, an idling torque control is performed to control the torque of the engine to an idling torque, Subsequently, target gear position torque control is performed to adjust the required torque so that the engine speed corresponds to the target gear position. [Effects of the Invention]

[0008] With the above-described configuration, the vehicle driving control system of the present invention performs idling torque control to suppress an increase in engine speed when the driver releases the clutch, and determines the target gear stage after the gear shift operation based on the driving conditions immediately before the clutch is engaged, and adjusts the required torque so that the engine speed corresponds to the target gear stage before the clutch is engaged, thereby reliably preventing a sudden change in engine speed when the clutch is engaged. [Brief explanation of the drawings]

[0009] [Figure 1]1 is a block diagram showing a vehicle cruise control system according to an embodiment of the present invention; [Figure 2] 10A and 10B are diagrams illustrating torque control and changes in engine speed during a gear shift operation. [Figure 3] 3 is a flowchart showing a travel control according to the first embodiment of the present invention. [Figure 4] 6 is a flowchart showing a travel control according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, a vehicle cruise control system according to an embodiment of the present invention includes an engine controller 10 that controls the output of the engine, a brake controller 20 that controls the braking force of the brake system, an ACC controller 30 that executes the ACC function, preceding vehicle detection means 31, and a group of sensors that acquire state values ​​used for cruise control.

[0011] The engine controller 10 constitutes an electronically controlled throttle system that controls the throttle opening of the engine using a throttle actuator in accordance with the accelerator pedal depression amount (torque demand) of the driver detected by an accelerator pedal sensor 12.

[0012] In addition to the accelerator pedal depression amount, the engine controller 10 is configured to acquire various detection values ​​indicating the engine operating state and the vehicle traveling state via the on-board network, such as the engine speed detected by the engine rotation sensor 11 (crank angle sensor, cam angle sensor, etc.), clutch-on information detected by the clutch pedal sensor 13, and vehicle speed calculated from the detection value of the wheel speed sensor 21, and to maintain the engine operating state optimally.

[0013] The brake controller 20 controls the electric hydraulic unit (brake actuator), controls the hydraulic pressure (basic brake pressure) generated in response to the driver's pedal force applied to the brake pedal, and controls the braking force of the brake device for each wheel. The electric hydraulic unit includes an electric pump and a control valve that switches between its hydraulic system and the hydraulic system on the master cylinder side. The brake controller 20 is built into the electric hydraulic unit as an ESC controller (ECU), and together with a wheel speed sensor 21 and a steering angle sensor and a yaw rate sensor (not shown), configures an ESC system.

[0014] The preceding vehicle detection means 31, which constitutes the ACC system together with the ACC controller 30, can be one or more detection devices such as millimeter wave radar, monocular camera, stereo camera, LIDAR, etc. that have the function of detecting the presence of preceding vehicles or objects (obstacles, structures) ahead of the vehicle and can also measure the relative distance (relative inter-vehicle time) between the vehicle and the preceding vehicle or obstacle.

[0015] The ACC controller 30 issues acceleration / deceleration commands to the engine controller 10 and the brake controller 20 in place of the driver's accelerator / brake operation based on the detection information from the preceding vehicle detection means 31 and the vehicle speed calculated from the detection value of the wheel speed sensor 21, thereby performing adaptive cruise control (constant speed driving / follow-up driving control).

[0016] That is, the engine controller 10, upon receiving a torque request (acceleration / deceleration command) from the ACC controller 30, controls the actuator output (throttle opening) to control the torque of the engine and accelerate or decelerate the vehicle to control the vehicle speed. Also, the brake controller 20, upon receiving a deceleration command from the ACC controller 30, controls the brake actuator to control the braking force of the brake device of each wheel to decelerate the vehicle and control the vehicle speed.

[0017] By the speed control of the ACC controller 30 as described above, the vehicle maintains the set vehicle speed and travels at a constant speed when there is no preceding vehicle ahead, and when there is a preceding vehicle ahead of the vehicle traveling at less than the set vehicle speed, the vehicle follows the preceding vehicle while maintaining a distance according to the set inter-vehicle time (time gear up = inter-vehicle distance / own vehicle speed).

[0018] The ACC controller 30 also includes a target gear determination unit 33 that determines a target gear of the transmission according to the running state of the vehicle. The target gear determination unit 33 acquires the current gear of the transmission from the vehicle speed and engine speed, and, if the engine speed deviates from the optimum rotational speed range, determines, as the target gear, a gear that will maintain the engine speed within the optimum rotational speed range by a gear change operation (shifting down / shifting up) with reference to the acceleration / deceleration command of the ACC controller 30.

[0019] The processing of the target gear position determination unit 33 as described above is constantly executed at a predetermined time rate while the ACC is operating, and the current gear position and target gear position are displayed on the shift indicator 34 in the instrument panel. In addition, the latest values ​​of information relating to the current gear position and target gear position are always held, so that when the driver performs a clutch release operation, the ACC controller 30 can immediately use this information as control information.

[0020] The ACC controller 30 is configured so that operations such as activating / deactivating the ACC function and setting the set vehicle speed and set inter-vehicle time can be performed using a setting switch 32 provided at the driver's seat (steering wheel, etc.).

[0021] The engine controller 10, brake controller 20, and ACC controller 30 described above are all configured as a computer (ECU) consisting of a ROM for storing control programs and setting data, a RAM for temporarily storing the results of arithmetic processing, a CPU for performing arithmetic processing, a communication I / F, etc., and are connected to a group of sensors via an in-vehicle network so that they can communicate with each other.

[0022] (Torque control during gear shifting while ACC is operating 1) In manual transmission vehicles, the driver still needs to change gears as needed even when the ACC function is operating. However, when driving at a set speed or following other vehicles at high speeds on highways, the frequency of gear changes is low, so the ACC function frees the driver from having to operate the accelerator and brakes, significantly reducing the burden on the driver, especially on long-distance driving.

[0023] On the other hand, on uphill roads where the driving load increases or on ordinary roads where stopping is unavoidable, it is necessary to perform appropriate gear changes in accordance with speed control. For this reason, the ACC function is generally designed to be deactivated below the minimum speed limit (for example, 30 km / h) (or in second gear or lower), but as will be described later, compatibility with all vehicle speeds, including deceleration, stopping, and restarting, is also being considered.

[0024] When shifting up or down while accelerating using the ACC function, the driver depresses the clutch pedal to release the clutch, operates the shift lever to change gear, and then gradually engages the clutch, which transmits engine torque to the drive wheels and allows the vehicle to transition to driving in the new gear.

[0025] At this time, clutch-on information from the clutch pedal sensor 13 is received by the engine controller 10 and the ACC controller 30. If clutch-on is detected during acceleration by the ACC function, the engine controller 10 assumes that a shift operation has begun, and executes idling torque control to reduce the engine torque to a target shift torque value (Ti; idling torque) set in the engine controller 10 that will not cause the engine to stall.

[0026] Because the ACC controller 30 is not programmed with an appropriate idling torque, when clutch engagement is detected, a torque request is made that is lower than the idling torque Ti, for example, 0 Nm, and the vehicle uses the engine controller 10 to realize the higher torque between the set torque (Ti) from the engine controller 10 and the torque request (Td) of the ACC controller 30. Therefore, when clutch engagement is detected, the idling torque Ti, which is the set torque from the engine controller 10, is realized.

[0027] That is, as shown in FIG. 2, at time ta, the engine controller 10 can immediately reduce the torque of the engine at its own discretion without waiting for the ACC controller 30 to cancel the torque request, and the engine speed drops to near the idling speed Ni, thereby preventing an unnecessary increase in engine speed due to the clutch release operation.

[0028] On the other hand, the recognition information of the engine controller 10 is referenced by the ACC controller 30, and the acceleration request from the ACC controller 30 to the engine controller 10 is temporarily canceled. If the engine speed is lower than the engine speed corresponding to the target gear stage determined by the target gear stage determination unit 33, the ACC controller 30 raises the torque request to achieve the engine speed corresponding to the target gear stage after the gear shift operation, and transitions to target gear stage torque control.

[0029] While checking the vehicle characteristics through compatibility and testing to confirm the relationship between engine torque and engine speed, target gear stage torque control may also be started at a timing earlier than the timing when engine torque = idling torque and engine speed < engine speed corresponding to the target gear stage (such as when engine speed of the target gear stage + α).

[0030] When the driver releases the clutch, the target gear stage determination unit 33 determines whether to perform a downshift / upshift operation for acceleration, a downshift operation for deceleration, or a clutch operation for deceleration and stop, considering the vehicle's immediate driving state (distance from the preceding vehicle, speed difference, acceleration difference, difference from the target vehicle speed), and determines the target gear stage after the shift operation. Based on this determination, the ACC controller 30 increases the required torque, and the engine controller 10 that receives the torque request from the ACC controller 30 realizes the required torque.

[0031] That is, as shown in FIG. 2, at tb, When the relationship of engine target torque (Ti) < ACC required torque (Td) is established, the torque increase is started at that timing.

[0032] For example, when the clutch is released during ACC acceleration in 5th gear and the engine torque is insufficient and the engine speed does not increase due to an increase in running resistance on an uphill road, the target gear stage determination unit 33 determines to downshift to 4th gear based on the difference from the target vehicle speed, etc. Based on this determination, the ACC controller 30 transmits a torque request to the engine controller 10 so as to approach the engine speed corresponding to 4th gear.

[0033] At this time, since the engine speed after downshifting needs to be higher than before the shift operation, the ACC controller 30 can prevent a sudden change in the engine speed (shift shock) at the time of clutch engagement by increasing the torque early at a relatively large rate of increase.

[0034] As a comparative example, assuming a configuration in which the torque request is raised after the semi-clutch state is detected, the engine speed tends to increase rapidly in the region where the clutch is fully engaged, as shown by the broken line in FIG. 2.

[0035] Conversely, if the clutch is released when the vehicle is shifted down to fourth gear during ACC acceleration and accelerated, and the engine speed increases due to excess engine torque caused by a decrease in running resistance and an increase in vehicle speed, the target gear stage determination unit 33 determines to shift up to fifth gear based on the vehicle speed and engine speed, and based on this determination, the ACC controller 30 sends a torque request to the engine controller 10 so that the engine speed will be equivalent to fifth gear.

[0036] In this case, the engine speed after the upshift is lower than before the gear change operation, so the ACC controller 30 can be expected to improve fuel economy by slowly increasing the torque at a relatively small rate of increase.

[0037] On the other hand, if the clutch is released during ACC deceleration, the target gear stage determination unit 33 determines to downshift in preparation for engine braking or re-acceleration based on the relative distance and speed difference with the preceding vehicle, the vehicle speed, and the engine speed. Based on this determination, the ACC controller 30 adjusts the required torque so that the engine speed after the downshift is higher than before the gear change operation, thereby mitigating the sudden change in engine speed (gear change shock) when the clutch is engaged.

[0038] During ACC deceleration, the torque is reduced or shifted to idling torque before the gear shift operation due to a deceleration command from the ACC controller 30, so the engine speed does not increase due to the clutch release operation.

[0039] Furthermore, if a deceleration and stop is predicted based on the vehicle's driving conditions, such as if a preceding vehicle is stopped within a predetermined distance, "neutral" is specified as the target gear position after the clutch release operation, and target gear position torque control is not performed, and idling torque control by the engine controller 10 continues. This makes it possible to suppress unnecessary torque requests and the associated fuel consumption, and to avoid the load of calculating the target gear position torque. However, if the preceding vehicle is traveling, the engine speed is maintained according to the vehicle speed. This allows a smooth transition to re-acceleration when the preceding vehicle accelerates again or moves out of its lane.

[0040] FIG. 3 shows a flowchart according to a first embodiment of the torque control during a gear shift operation while the ACC is operating as described above.

[0041] If clutch pedal ON is detected (step 102; YES) while the ACC function is operating (step 101; YES), it is determined that a shift operation has been initiated, and the process shifts to idling torque control (step 103).

[0042] In parallel with this, the target gear stage determination unit 33 takes into consideration the vehicle's immediate driving state and determines whether the downshift / upshift operation is for acceleration or deceleration, and determines the target gear stage accordingly.If it is determined to be a downshift (step 110; YES), when the engine torque becomes idling torque or the engine speed becomes lower than the engine speed corresponding to the target gear stage, the unit transitions to downshift torque control, which increases the torque request at a relatively large rate of increase (step 120).

[0043] On the other hand, if it is determined that an upshift is required (step 110; NO), when the engine torque becomes idling torque or the engine speed becomes lower than the engine speed corresponding to the target gear stage, the process transitions to upshift torque control, which increases the torque request at a relatively small rate of increase (step 130).

[0044] (Torque control during gear shifting while ACC is operating 2) The above-described process of clutch release, idling torque control, and upshift torque control / upshift torque control must be completed in the middle of the driver's gear change operation, so it is preferable to execute it within one second. However, the timing of gear change operations and half-clutch operation varies depending on individuals and driving conditions such as during acceleration or deceleration.

[0045] Therefore, in the control of the second embodiment, if a half-clutch, i.e., partial engagement of the clutch, is detected during the target gear stage torque control (shift-up torque control / shift-up torque control), the torque increase rate is corrected to accelerate reaching the target engine speed.

[0046] The clutch engagement rate α can be estimated as the ratio of the transmission input shaft rotation speed Nc to the engine rotation speed N detected by the engine rotation sensor 11 using the vehicle speed V, gear ratio Gn, final reduction ratio F, effective tire radius R, and coefficient k (unit adjustment and N / V ratio offset in a fully engaged state) as shown in the following equation. Clutch engagement ratio α = Nc / N = kV / GnFRN

[0047] That is, a rotation speed Nc corresponding to the clutch engagement rate α is transmitted to the transmission with respect to the engine rotation speed N. Therefore, the engine controller 10 monitors the engine rotation speed N and the clutch engagement rate α to determine the clutch engagement state (half-clutch state), and when partial engagement of the clutch is detected, corrects the rate of increase in the torque request from the ACC controller 30 to a rate of increase greater than the rate at the start of control, thereby enabling shift control utilizing half-clutch operation while mitigating shift shock.

[0048] FIG. 4 shows a flowchart according to a second embodiment of the torque control during a gear shift operation while the ACC is operating as described above.

[0049] If clutch pedal ON is detected (step 102; YES) while the ACC function is operating (step 101; YES), it is determined that a shift operation has been initiated, and the process transitions to idling torque control (step 103). Up to this point, the process is the same as in the first embodiment.

[0050] In parallel with this, the target gear stage determination unit 33 takes into consideration the vehicle's immediate driving state and determines whether the operation is a downshift / upshift operation for acceleration, a downshift operation for deceleration, or a clutch operation for deceleration and stopping accompanying the stopping of a preceding vehicle, and determines the target gear stage according to the determination.If it is determined that the clutch operation is for deceleration and stopping (step 104; YES), it regards the transmission as being held in neutral and continues idling torque control (step 105).

[0051] In step 104, if there is no preceding vehicle stopped within a predetermined distance and a predetermined vehicle speed is being maintained (step 104; NO), and it is determined that a downshift is required (step 110; YES), when the engine torque becomes idling torque or the engine speed becomes lower than the engine speed corresponding to the target gear, the system transitions to downshift torque control, which increases the torque request at a relatively large initial increase rate (step 120).

[0052] On the other hand, if it is determined that an upshift is required (step 110; NO), when the engine torque becomes idling torque or the engine speed becomes lower than the engine speed corresponding to the target gear stage, the process transitions to upshift torque control, which increases the torque request at a relatively small initial increase rate (step 130).

[0053] After transitioning to downshift torque control or upshift torque control and increasing the torque demand at the respective starting increase rates, if the engine speed reaches the target engine speed corresponding to the respective gear stage (step 121; YES, step 131; YES), the downshift torque control or upshift torque control is terminated and ACC driving is resumed.

[0054] On the other hand, if partial engagement of the clutch is detected (step 122; YES, step 132; YES) before the engine speed reaches the target engine speed corresponding to each gear (step 121; NO, step 131; NO), the respective initial increase rates are modified to larger increase rates to accelerate the reaching of the target engine speed (steps 123, 133).

[0055] (Torque control during gear shifting while ACC is operating 3) When the acceleration or deceleration in the speed control by the ACC controller 30 is large, it is preferable to end the gear shift operation as soon as possible and return to the power transmission state. Therefore, the increase rate (increase coefficient) of the torque request from the ACC controller 30 in the target gear stage torque control (shift-up torque control / shift-up torque control) is set as follows: (i) a first rate of increase in a cruising state (first driving state) in which acceleration or deceleration is zero or within a threshold value near zero; (ii) a second rate of increase greater than the first rate of increase in an acceleration / deceleration state (second running state) in which the acceleration or deceleration is greater than the threshold value; is set, and an increase rate corresponding to the running state can be set when transitioning to target gear stage torque control.

[0056] (Torque control during gear shifting while ACC is operating 4) The acceleration and deceleration characteristics of a vehicle change depending on the weight of the vehicle, such as the number of occupants and the load on the vehicle. Therefore, when the vehicle is heavy, it is preferable to finish the gear shift operation as quickly as possible and return to the power transmission state. (i) a first climb rate in a first control mode (light mode) when the number of occupants and / or load of the vehicle is less than a predetermined value; (ii) a second rate of rise greater than the first rate of rise in a second control mode (weight mode) when the number of occupants and / or the load of the vehicle is equal to or greater than a predetermined value; It is also possible to provide a control mode selector 32 in advance.

[0057] In the above embodiment, the target gear position determination unit 33 is described as being provided in the ACC controller 30, but it may also be provided as a device independent of the ACC controller 30.

[0058] Furthermore, in the above embodiment, the case where the acceleration / deceleration request from the ACC controller 30 is sent directly to the engine controller 10 and / or the brake controller 20 is shown, but it is also possible to implement a configuration in which a drive control controller (braking / driving controller) is provided between the ACC controller 30 and the engine controller 10 and the brake controller 20, and the acceleration / deceleration request of the ACC controller 30, particularly the deceleration request, is arbitrated by the drive control controller and sent to the engine controller 10 / brake controller 20.

[0059] Although several embodiments of the present invention have been described above, it should be noted that the present invention is not limited to the above-described embodiments, and further modifications and variations are possible within the scope of the present invention based on the technical concept of the present invention. [Explanation of symbols]

[0060] 10 Engine Controller 11 Engine revolution sensor 12 Accelerator pedal sensor 13 Clutch pedal sensor 20 Brake controller 21 Wheel speed sensor 30 ACC controller 31 Preceding vehicle detection means 32 Setting switch 33 Target gear stage determination unit 34 Shift indicator

Claims

1. A vehicle driving control system, A manual transmission and a clutch that releasably transmits engine torque to the transmission; an ACC controller that controls the speed of the vehicle to perform an ACC function of maintaining a set vehicle speed when there is no preceding vehicle, and maintaining a set inter-vehicle time when there is a preceding vehicle traveling at a speed slower than the set vehicle speed; a target gear position determining means for determining a target gear position of the transmission in accordance with a running state of the vehicle while the vehicle is running using the ACC function, When the clutch is released during operation of the ACC function, an idling torque control is performed to control the torque of the engine to an idling torque, The vehicle driving control system is configured to subsequently perform target gear position torque control, which adjusts the required torque so that the engine speed corresponds to the target gear position.

2. 2. The vehicle driving control system according to claim 1, wherein the target gear position torque control is executed when the engine torque becomes the idling torque or when the engine speed becomes lower than the engine speed corresponding to the target gear position.

3. an engine controller for controlling the torque of the engine; the idling torque control is executed using a target torque by the engine controller as the idling torque, The target gear stage torque control is executed by increasing the torque required by the ACC controller from a required value lower than the idling torque, and the engine controller controlling the engine torque in accordance with the higher required value between the target torque and the required torque from the ACC controller. The vehicle cruise control system according to claim 1 .

4. the target gear position determining means determines whether the target gear position corresponds to a downshift, an upshift, or a neutral position; 4. The vehicle driving control system according to claim 3, wherein the increase in the required torque in the target gear stage torque control includes a first increase rate during the upshift and a second increase rate during the downshift, the second increase rate being greater than the first increase rate.

5. 4. The vehicle driving control system according to claim 3, wherein the increase in the required torque in the target gear stage torque control includes a first increase rate in a first driving state in which the acceleration or deceleration in the speed control by the ACC controller is zero or close to zero, and a second increase rate in a second driving state in which the acceleration or deceleration in the speed control is greater than in the first driving state, and the second increase rate is greater than the first increase rate.

6. the ACC controller has a first control mode when the number of occupants and / or the load weight of the vehicle is less than a predetermined value, and a second control mode when the number of occupants and / or the load weight of the vehicle is equal to or greater than the predetermined value, 4. The vehicle driving control system according to claim 3, wherein the increase in the required torque in the target gear stage torque control includes a first increase rate in the first control mode and a second increase rate in the second control mode, the second increase rate being greater than the first increase rate.

7. 2. The vehicle driving control system according to claim 1, wherein when the preceding vehicle is stopped within a predetermined distance, the engine speed corresponding to the target gear stage is set as the idling speed and the target gear stage torque control is not performed, and when the preceding vehicle is moving, the engine speed is set according to the vehicle speed.

8. 4. The vehicle cruise control system according to claim 3, wherein the increase in the required torque in the target gear stage torque control is initiated at a predetermined initial increase rate, and is modified to a modified increase rate greater than the initial increase rate if partial engagement of the clutch is detected before the engine speed corresponding to the target gear stage is reached.

9. 6. The vehicle driving control system of claim 5, wherein the increase in the required torque in the target gear stage torque control is initiated at a predetermined initial increase rate, and if partial engagement of the clutch is detected before the engine speed corresponding to the target gear stage is reached, the increase is corrected to a corrected increase rate that is greater than the initial increase rate, and the corrected increase rate is greater than the second increase rate in the second driving state.

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