Vehicle control device

Abstract

To improve shift feeling in a curve section during ACC traveling in a vehicle equipped with a stepped automatic transmission.SOLUTION: A control device for a vehicle equipped with a stepped automatic transmission includes: an ACC function that allows a self vehicle to travel at a setting speed when a preceding vehicle is not present on a lane where the self vehicle is traveling and that issues an acceleration request / deceleration request such that the self vehicle can travel following the preceding vehicle while maintaining a setting inter-vehicle time when the preceding vehicle is present on a lane where the self vehicle is traveling; and a curve traveling assist function that issues a deceleration request when it is detected that the vehicle enters a curve having a predetermined curvature or larger and a curve traveling condition is satisfied. When the curve traveling condition is satisfied during traveling by the ACC function, an upper limit of gear shifting by the automatic transmission is limited to one stage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device, and more particularly to a vehicle control device equipped with an ACC function. [Background technology]

[0002] As a driving assistance function, ACC (adaptive cruise control) has been put into practical use. If there is no preceding vehicle in the vehicle's lane, the vehicle will travel at a constant speed at a set speed, and if there is a preceding vehicle in the vehicle's lane traveling at a speed slower than the set speed, the vehicle will follow the preceding vehicle while maintaining a set time interval.

[0003] For example, Patent Document 1 discloses that a control device for a vehicle having an ACC function is provided with a turning radius calculation means for calculating the turning radius of the vehicle itself, and an upper limit vehicle speed setting means for setting an upper limit vehicle speed according to the calculated turning radius, and controls the vehicle speed of the vehicle itself during a turn to be equal to or lower than the upper limit vehicle speed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-68752 Summary of the Invention [Problem to be solved by the invention]

[0005] In a vehicle equipped with a stepped automatic transmission, when driving in ACC mode on a flat road or downhill with low running resistance and entering a sharp curve, the required torque may be significantly reduced to suppress acceleration, causing the vehicle to upshift. After that, when the required torque is increased to accelerate after passing the curve, the vehicle may downshift. While this type of upshifting has the advantage of lowering engine speed and reducing fuel consumption, changing gears by upshifting or downshifting between two stages in an extremely short period of time results in a large change in driving force, which can impair the feel of the vehicle.

[0006] The present invention has been made in consideration of the above-described circumstances, and its purpose is to improve the gear shift feeling in curved sections during ACC driving in a vehicle equipped with a stepped automatic transmission. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: A control device for a vehicle equipped with a stepped automatic transmission, an ACC function that drives at a set vehicle speed when there is no preceding vehicle in the vehicle's lane, and requests acceleration / deceleration to follow the preceding vehicle while maintaining a set inter-vehicle time when there is a preceding vehicle in the vehicle's lane; a curve driving support function that requests deceleration when an approach to a curve with a predetermined curvature or more is detected and a curve driving condition is met; In those having The vehicle is characterized in that, when the curve driving condition is met while the vehicle is traveling using the ACC function, the upper limit of the gear shift of the automatic transmission is limited to one gear. [Effects of the Invention]

[0008] As described above, the vehicle control device of the present invention limits the upper limit of gear changes to one gear when entry into a curve with a predetermined curvature or greater is detected during ACC driving. Therefore, even if a torque reduction request is issued due to a deceleration request, two-stage gear changes in an extremely short period of time are avoided, which is advantageous in improving the gear change feeling in curved sections. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a vehicle cruise control system. [Figure 2] 3 is a flowchart showing a gear shift control according to the first embodiment of the present invention. [Figure 3] 10 is a flowchart showing a gear shift control according to a second embodiment of the present invention. [Figure 4] FIG. 1 is a schematic diagram showing a road including a curve section. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, a vehicle 1 includes an internal combustion engine 2 and a stepped automatic transmission 4 via a clutch 3 in a torque transmission path from the engine 2 to drive wheels (6).

[0011] The automatic transmission 4 is configured as an AMT (Automated Manual Transmission) type automatic transmission equipped with an MT type shift mechanism, for example, a parallel gear type shift mechanism with constant mesh synchromesh, and a shift actuator that performs the gear stage change operation, and is equipped with an AMT controller 40 that performs the shift operation by referring to a shift map (automatic shift line diagram) based on the vehicle speed and throttle opening. 。

[0012] The gear change actuator includes a select actuator that switches between P / R / N / D ranges and high / low gears according to the operating position of a select lever (not shown), and a shift actuator that performs shift operations, and works in conjunction with the clutch actuator to perform gear change operations consisting of clutch release, gear change, and clutch engagement.

[0013] The vehicle 1 is equipped with an engine controller 20 that controls the output of the engine 2 in accordance with a throttle opening (torque request) given by operating an accelerator pedal (not shown) and acceleration / deceleration commands from an ACC controller 10 (described later). The AMT controller 40, through cooperative control with the engine controller 20, executes engine control linked to the clutch release / engagement operation in the above-mentioned gear shift operation.

[0014] The vehicle 1 is equipped with a brake system that constitutes an ABS / vehicle behavior stabilization device, which includes a brake controller 30 that can individually control the braking forces of brakes 36 for the left and right front wheels 6 and brakes 37 for the left and right rear wheels 7 in response to brake pedal operation (not shown) or a deceleration command from an ACC controller 10 (described later), a brake actuator (hydraulic actuator) (not shown), wheel speed sensors 36 for the left and right front wheels 6, and wheel speed sensors 37 for the left and right rear wheels 7.

[0015] The vehicle 1 having the above-described basic configuration is equipped with a preceding vehicle detection means 11 that constitutes an ACC system together with the ACC controller 10. The preceding vehicle detection means 11 can be one or more detection means, such as millimeter-wave radar, a monocular camera, a stereo camera, or LIDAR, that have the function of detecting the presence of a preceding vehicle or object (obstacle, structure) ahead of the host vehicle and that can measure the relative distance (relative inter-vehicle time) between the host vehicle and the preceding vehicle or obstacle.

[0016] The ACC controller 10 is configured to issue acceleration / deceleration commands (torque request / brake request) to the engine controller 20 and brake controller 30 in place of the driver's accelerator / brake operation based on the detection information from the preceding vehicle detection means 11 and the vehicle speed calculated from the detection values ​​of the wheel speed sensors 36, 37, and to execute adaptive cruise control (constant speed running / follow-up running control / deceleration stop / restart control) compatible with all vehicle speed ranges.

[0017] That is, the brake controller 30, which receives a deceleration command from the ACC controller 10, issues a brake request (hydraulic pressure request) to the brake actuator and controls the braking force of the brakes 36, 37, thereby controlling the vehicle speed. Furthermore, the engine controller 20, which receives an acceleration / deceleration command (torque increase request / torque decrease request) from the ACC controller 10, controls the actuator output (throttle opening) of the engine 2, thereby controlling the torque of the engine 2 and controlling the vehicle speed.

[0018] By the above control of the ACC controller 10, the vehicle 1 maintains the set vehicle speed when there is no preceding vehicle, and when it catches up with the preceding vehicle, it follows the preceding vehicle while maintaining a distance according to a predetermined inter-vehicle time (time gear up = inter-vehicle distance / own vehicle speed) in accordance with the speed of the preceding vehicle. Furthermore, when the vehicle 1 catches up with a preceding vehicle that is decelerating and stopping, it decelerates and stops while ensuring a predetermined inter-vehicle distance, and if the preceding vehicle starts moving within the predetermined time, it restarts to match it and continues following.

[0019] The engine controller 20, AMT controller 40, brake controller 30, and ACC controller 10 described above are all configured with a microcomputer (MCU) 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 including a preceding vehicle detection means 11 via an in-vehicle network (such as CAN) so that they can communicate with each other.

[0020] (Curve driving assistance function during ACC driving) The ACC controller 10 has a curve driving assistance function that requests deceleration when it detects that the vehicle is entering a curve with a curvature of a predetermined value or more during ACC driving, in order to control the vehicle speed to a value that allows stable driving around the curve (curve driving speed).

[0021] As a means for detecting a curve with a predetermined curvature or more, known means can be used, such as a yaw rate sensor 12, a steering angle sensor 13, image analysis of a forward camera 14 which can also constitute a preceding vehicle detection means 11, matching of position information detected by a positioning system 15 (GNSS, navigation system) with map information (curve curvature information), or a combination of these.

[0022] For example, when using the yaw rate sensor 12, a lookup table or the like that specifies a yaw rate threshold corresponding to a vehicle speed at which stable travel is possible depending on the radius of curvature of the curve is prepared in advance in a ROM area, and when the yaw rate detected by the yaw rate sensor 12 reaches the yaw rate threshold specified depending on the current vehicle speed, it can be determined that the vehicle is entering a curve with a predetermined curvature or greater. At this time, a yaw rate calculated from the difference between the wheel speeds detected by the left and right wheel speed sensors 16, 17 can also be used in combination.

[0023] Furthermore, when image analysis by the front camera 14 is used, lane markings (division lines, roadside lines) on which the vehicle is traveling are recognized, and the curvature of the curve can be estimated by performing coordinate transformation (projection transformation) on an overhead image. When image analysis by the front camera 14 or position information and map information from the positioning system 15 are used, it is possible to detect the curve ahead on the road before entering the curve, so when approach to the curve is detected by these means, it is also possible to start monitoring the curve curvature by the yaw rate sensor 12 and calculating the upper limit vehicle speed for traveling on the curve. The curve detection means described above is also used to determine the end of traveling on a curve when passing through a curve.

[0024] During ACC driving, if the curve detection means detects the vehicle entering a curve with a predetermined curvature or greater and the vehicle speed at that time (ACC set vehicle speed or preceding vehicle following vehicle speed) is predicted to exceed the vehicle speed at which stable driving around the curve is possible, i.e., if the curve driving conditions are met, the ACC controller 10 switches to curve driving assistance mode and issues a deceleration request to the engine controller 20 and brake controller 30 to control the vehicle speed to a speed at which stable driving around the curve is possible, regardless of the ACC set vehicle speed or preceding vehicle following vehicle speed.

[0025] In response to a deceleration request (torque reduction request / brake request) from the ACC controller 10, the engine controller 20 reduces the torque of the engine 2, and if the deceleration request value is equal to or greater than a predetermined value, the brake controller 20 activates the brakes 6, 7. At this time, the deceleration request (torque reduction request) to the engine controller 20 is also shared with the AMT controller 40, which executes a gear shift operation by referring to a gear shift map based on the current vehicle speed and the torque reduction request value.

[0026] Incidentally, when driving in ACC mode on a flat road with low rolling resistance or on a downhill slope and entering a sharp curve, the required torque value drops to suppress acceleration, causing the vehicle to shift up. However, if the required torque value drops significantly, for example to zero (Nm), the gear may change in two stages in an extremely short period of time, impairing the shifting feel, as already mentioned.

[0027] (First embodiment) Therefore, in the control according to the present invention, when entry into a curve of a predetermined curvature or greater is detected and the curve traveling condition is met, the upper limit of gear shifts of the automatic transmission 4 is limited to one gear.

[0028] That is, when the curve driving condition is met (curve driving flag), the ACC controller 10 requests deceleration for curve driving assistance, but when the curve driving condition is met, the AMT controller 40 limits the upshift to one gear regardless of the torque requirement value.

[0029] For example, when the AMT controller 40 performs one upshift in response to a deceleration request in the curve driving support mode, the ACC controller 10, which has acquired the upshift, prohibits the AMT controller 40 from further upshifting until the curve driving is completed.

[0030] For example, when the vehicle 1 is traveling in 4th gear of the automatic transmission 4 with 6 forward gears while driving in ACC mode and enters a curve, if the vehicle 1 shifts up to 5th gear in response to a deceleration request from the ACC controller 10, the vehicle 1 is prohibited from shifting up to 6th gear until the vehicle has finished driving through the curve.

[0031] This allows the vehicle to immediately shift up to fourth gear in response to an acceleration request (torque increase request) when the vehicle transitions to straight driving after completing a curve or when the vehicle speed limit is relaxed due to a decrease in yaw rate as the curvature of the curve decreases, thereby maintaining good acceleration / deceleration performance and gear change feeling.

[0032] (Second embodiment) Also, when the curve traveling condition is met, the upper limit of the gear stage change can be limited to one stage only for a predetermined period of time, rather than until the curve traveling ends.

[0033] That is, when the curve driving condition is met, the AMT controller 40 performs one upshift in response to a deceleration request for curve driving assistance, and at the same time, the ACC controller 10, which has acquired the upshift, starts timing a predetermined time T1 (for example, 1 to 2 seconds), and prohibits the AMT controller 40 from further upshifting until timing of this predetermined time T1 ends.

[0034] If the curve driving condition is met when the predetermined time T1 has elapsed, the gear change restriction is reset, timing of the predetermined time T1 is started anew, and the upper limit of gear change of the automatic transmission 4 is limited to one gear until the end of timing (shifting up by one further gear is permitted).

[0035] For example, if the vehicle is traveling in fourth gear of the automatic transmission 4 with six forward gears during ACC driving and enters a curve, and a deceleration request from the ACC controller 10 causes an upshift to fifth gear, an upshift to sixth gear is prohibited until a predetermined time T1 has elapsed. However, if the deceleration request for the curve continues even after the predetermined time T1 has elapsed, an upshift to sixth gear is permitted. Upon upshifting to sixth gear, another predetermined time T1 begins to be counted. Until the predetermined time T1 has elapsed, a downshift to fifth gear is permitted, but a downshift to fourth gear is prohibited. After the predetermined time T1 has elapsed, a downshift to fourth gear is permitted. In this case, too, a two-stage gear change in an extremely short period of time is prevented, maintaining a good gear change feeling.

[0036] (Third embodiment) On mountain roads, etc., there are often repeated curves of a predetermined curvature or greater. Therefore, when the curve driving condition is met and the vehicle transitions to curve driving, a curve driving history is stored, and control can be added to prohibit further gear changes if curve driving is repeated for a predetermined time T2 (for example, 5 to 30 seconds) that is longer than the predetermined time T1.

[0037] That is, when a curve driving condition is first met, a predetermined time T2 is measured in parallel with the measurement of the predetermined time T1, and the curve driving history is maintained until the end of the measurement of the predetermined time T2. If the next curve driving condition is not met during that time, the curve driving history is cleared. On the other hand, if the next curve driving condition is met before the end of the measurement of the predetermined time T2, a new measurement of the predetermined time T2 is performed, and the AMT controller 40 is prohibited from changing the gear position. This control has the advantage that when curves of a predetermined curvature or greater are repeatedly encountered, the gear position is fixed, thereby avoiding gear changes and achieving good acceleration / deceleration performance.

[0038] (First Example) Next, an example of the curve running support function during ACC running corresponding to the third embodiment will be described with reference to the flowchart of FIG. 2 and FIG.

[0039] First, at time t1, the vehicle is traveling in fourth gear through the curve section Z1, but since the curvature does not satisfy the predetermined curvature, the ACC controller 10 only performs speed control to maintain the set vehicle speed (step 100).

[0040] After that, even after time t2, when the vehicle enters straight section Z2, speed control to maintain the set vehicle speed continues, but at time t2', a curve section Z3 with a predetermined curvature or greater is detected ahead on the road, and when the curve driving condition is met at time t3 (step 110; YES), the ACC controller 10 refers to the curve driving history (step 112), and if there is no curve driving history within the predetermined time T2 (step 112; YES), it issues a deceleration request to decelerate the vehicle to a speed that allows stable driving on the curve section Z3, and at the same time limits the gear change to an upper limit of one gear (step 113).

[0041] In response to a deceleration request (torque reduction request) from the ACC controller 10, the AMT controller 40 shifts up to fifth gear, but because gear changes are limited to an upper limit of one gear during the predetermined time T1, an upshift to sixth gear is not performed (step 113).

[0042] After that, at time t4 after passing through a curve (t3'), a straight section Z4 is detected and the curve end condition is met (step 114; YES), the upper limit of one gear change restriction is released (step 120), and a downshift to fourth gear is performed in response to an acceleration request (torque increase request) with the set vehicle speed as the target vehicle speed, and acceleration begins. t The clocking of the predetermined time T2 continues from point 3, and the curve driving history is maintained since the curve driving condition is met in the curve section Z3.

[0043] After that, the vehicle travels through a short straight section Z4, and at time t4', a curve section Z5 with a curvature of a predetermined value or more is detected ahead on the road. If the curve travel condition is met at time t5 before the predetermined time T2 has elapsed (step 110; YES), the ACC controller 10 refers to the curve travel history (step 112). Since there is a curve travel history within the predetermined time T2 (step 112; NO), the ACC controller 10 issues a deceleration request to decelerate the vehicle to a speed that allows stable travel through the curve section Z5, and simultaneously prohibits gear changes (step 115). Accordingly, the vehicle is fixed in fourth gear while traveling through the curve section Z5.

[0044] After that, after going around a curve, a quasi-straight section Z6 is detected at time t6, and when the curve end condition is met (step 116; YES), the speed change restriction is released (step 120). However, since the gear position has been fixed to fourth speed since going around the curve, acceleration is immediately started by an acceleration request (torque increase request) with the set vehicle speed as the target vehicle speed. However, at time t The clocking of the predetermined time T2 continues from point Z5, and the curve driving history in curve section Z5 is maintained.

[0045] Thereafter, the vehicle travels through the quasi-straight section Z6, and when a predetermined time T2 has elapsed, the curve travel history for the curve section Z5 is cleared.

[0046] In addition, if the vehicle stops while traveling on a curve, the curve end condition is met and the speed change restriction is released. Also, since the curve driving assistance function operates on the premise of ACC driving, if the ACC function is overridden by the driver's intervention in braking or accelerator operation, the speed change restriction is released and the curve driving assistance function is also stopped.

[0047] In the above first example (third embodiment), the case was described where timing of the predetermined time T2 for retaining the curve driving history starts from the point in time when the curve driving condition is met, but timing of the predetermined time T2 (T2') may also start from the point in time when the curve section is passed and the curve driving end condition is met.

[0048] Furthermore, instead of prohibiting gear changes when curves are repeated within a predetermined time T2 (T2'), it is also possible to set up a switch that can be manually operated by the driver, for example, a mountain road mode switch, and when this mountain road mode switch is turned on and mountain road mode (gear stage change prohibition mode) is specified, a gear stage change can be immediately prohibited when a curve driving condition is met.

[0049] (Second Example) FIG. 3 is a flowchart showing a second embodiment of the curve driving support function including the mountain road mode switch, and will be described with reference to FIGS.

[0050] During ACC driving (step 100), if the mountain road mode switch is turned on (step 101; YES), for example, when the vehicle is driving in fourth gear on a straight section Z2 and at time t2' a curve section Z3 with a predetermined curvature or greater is detected ahead on the road, and the curve driving condition is met at time t3 (step 102; YES), the ACC controller 10 issues a deceleration request to reduce the vehicle speed to a level that allows stable driving on the curve section Z3, and simultaneously prohibits a gear change (step 103). As a result, the gear is fixed to fourth gear while driving on the curve section Z3.

[0051] After that, at time t4, when the straight section Z4 is detected and the curve end condition is met (step 104; YES), the speed change restriction is released (step 120). However, since the gear stage was fixed to fourth speed, acceleration is immediately started due to an acceleration request (torque increase request) with the set vehicle speed as the target vehicle speed.

[0052] After that, the vehicle travels through a short straight section Z4, and at time t4', a curve section Z5 with a predetermined curvature or greater is detected ahead on the road. When the curve travel condition is met at time t5 (step 102; YES), the ACC controller 10 requests deceleration to reduce the vehicle speed to a level at which the vehicle can travel stably through the curve section Z5, and simultaneously prohibits a gear change (step 103).

[0053] In this way, when the mountain road mode switch is turned on, if the vehicle enters a curve with a curvature of a predetermined value or greater while driving in ACC mode, changing gears while driving on the curve is prohibited, which has the advantage of avoiding gear changes while driving on the curve and providing good acceleration and deceleration performance.

[0054] In particular, in a vehicle 1 equipped with an AMT type automatic transmission 4, shifting involves instantaneous torque control linked to clutch engagement and disengagement, so that the gear stage is fixed while driving around a curve, which has the advantage of maintaining a good feeling when driving around a curve and allowing ACC driving that is suitable for AMT vehicles, which have high power transmission efficiency when the clutch is engaged.

[0055] In the above embodiment, the curve assistance function in a vehicle equipped with an ACC function has been described. However, the present invention can also be implemented as a curve assistance function in a vehicle equipped with an LKA (Lane Keeping Assist) function that recognizes the lane in which the vehicle is traveling using a forward detection means exemplified as the forward camera 14 or the preceding vehicle detection means 11, and performs automatic steering or steering assistance to maintain the vehicle within the lane in which the vehicle is traveling, or in a vehicle equipped with an ADAS (Advanced Driver Assistance System) that combines an ACC function (vehicle length direction control) and an LKA function (vehicle width direction control).

[0056] 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 various modifications and variations are possible based on the technical concept of the present invention. [Explanation of symbols]

[0057] 1 vehicle 2 engines 3. Clutch 4. Automatic transmission 10 ACC controller 11. Means for detecting preceding vehicles 12 Yaw rate sensor 13 Steering angle sensor 14 Front camera 15 Positioning System 16,17 Wheel speed sensor 20 Engine Controller 30 Brake controller 36,37 Brakes 40 AMT Controller

Claims

1. A control device for a vehicle equipped with a stepped automatic transmission, an ACC function that drives the vehicle at a set vehicle speed when there is no preceding vehicle in the vehicle's lane, and requests acceleration / deceleration to follow the preceding vehicle while maintaining a set inter-vehicle time when there is a preceding vehicle in the vehicle's lane; a curve driving support function that issues a deceleration request when the curve detection means detects that the vehicle is entering a curve with a curvature of a predetermined value or more and a curve driving condition is met; and In those having a control device for a vehicle configured to limit an upper limit of gear shifting of the automatic transmission to one gear when the curve driving condition is met while the vehicle is traveling using the ACC function.

2. 2. The vehicle control device according to claim 1, wherein the control device is configured to start timing a first predetermined time when the curve driving condition is met, and to reset the restriction on gear position change when the curve driving condition is met after the first predetermined time has elapsed.

3. If the curve driving condition is met, the curve driving history is stored, and then: (i) if the next curve driving condition is not met within a second predetermined time, clear the curve driving history; (ii) A vehicle control device as described in claim 1, characterized in that if the next curve driving condition is met within a second predetermined time, the curve driving history is stored, and thereafter, gear changes are prohibited until the curve end condition is met.

4. A control device for a vehicle as described in any one of claims 1 to 3, characterized in that, when a gear stage change prohibition mode is specified by turning on a manually operable switch, a gear stage change is prohibited when the curve driving condition is met.

5. 5. The vehicle control device according to claim 1, wherein the automatic transmission is an AMT-type automatic transmission including a clutch that transmits engine output to a transmission mechanism, a clutch actuator that engages and disengages the clutch, a shift actuator that changes the gear stage of the transmission mechanism, and an AMT controller that controls the shift actuator and the clutch actuator to change the gear stage.

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