Vehicle driving control device

Abstract

To provide a travel controller for a vehicle which, even on an uphill road, can provide the same feeling when a vehicle is decelerated and stopped as on a flat road.SOLUTION: There is provided a travel controller (12) for a vehicle (1) including: engine control means (10) for making a torque request to an engine (2); brake control means (20) for controlling brake force in response to a brake request; gradient detection means (13) for detecting a road surface gradient; and preceding vehicle detection means (11) for detecting a preceding vehicle. The travel controller has the function of decelerating and stopping the own vehicle while ensuring a prescribed inter-vehicle distance if the preceding vehicle detected by the preceding vehicle detection means is decelerated and stopped, and executes pitching suppression control to temporarily reduce the pressure of the brake force immediately before the own vehicle is stopped, and then increase the pressure. At a time point when the own vehicle reaches a first vehicle speed (Va) at which it is determined that the own vehicle is just about to be stopped, if the road surface gradient equal to or greater than a prescribed threshold is detected by the gradient detection means (13), a prescribed torque request is made in parallel with the pitching suppression control.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle cruise control device, and more particularly to a vehicle cruise control device having an automatic braking function. [Background technology]

[0002] In a vehicle cruise control device having an automatic brake function, for example, a cruise control device having an all-speed range ACC function, when the vehicle catches up with a preceding vehicle that is decelerating and stopping, or when the preceding vehicle being followed decelerates and stops, the automatic brake is activated to decelerate and stop the vehicle. In order to suppress the rebound (pitching vibration) during such deceleration and stopping, a control that temporarily reduces the brake pressure immediately before stopping is known (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 01-122764 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, in vehicles equipped with an AMT type automatic transmission, the feeling when decelerating and stopping can be improved by releasing the clutch and disconnecting the engine from the drive shaft when decelerating and stopping due to automatic braking. However, when this control is used in combination with the pitching suppression control described above on an uphill road, it was found that there was a tendency for the driver to feel a slight backward movement at the stopped position until the braking force was built up after the pressure was reduced.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a vehicle driving control device that enables the driver to obtain the same feeling when decelerating and stopping on an uphill road as on a flat road. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides Torque Requirement Control the engine according to A vehicle travel control device including an engine control means, a brake control means for controlling a braking force in response to a brake request, an inclination detection means for detecting a road surface inclination, and a preceding vehicle detection means for detecting a preceding vehicle, A vehicle control system having a function of decelerating and stopping a preceding vehicle detected by the preceding vehicle detection means while securing a predetermined vehicle distance, and configured to implement pitching suppression control for temporarily reducing the braking force and then increasing the braking force immediately before the preceding vehicle stops, When the vehicle reaches a first vehicle speed at which it is determined that the vehicle is about to stop, if the inclination detection means detects a road surface gradient equal to or greater than a predetermined threshold, a predetermined torque request is made in accordance with the pitching suppression control. The first vehicle speed is greater than the vehicle speed at the time of increasing the braking force in the pitching suppression control. The present invention relates to a vehicle driving control device. Effect of the Invention

[0007] As described above, when the vehicle driving control device of the present invention decelerates and stops in accordance with the vehicle ahead, if a road gradient equal to or greater than a predetermined threshold is detected, a predetermined torque is requested from the engine in conjunction with pitching suppression control which temporarily reduces and then increases the braking force, so that even on uphill roads the vehicle can obtain the same feeling of decelerating and stopping as on flat roads without the sensation of the vehicle jerking backwards. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a vehicle cruise control system. [Diagram 2] 1A is a schematic diagram showing deceleration and stopping of a vehicle on an uphill road; [Diagram 3] 4 is a time chart showing a driving control according to an embodiment of the present invention. [Figure 4] 4 is a flowchart showing a driving control according to the embodiment of the present invention. [Diagram 5]5 is a flowchart showing a control performed when the brake pedal is operated in the travel control according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, a vehicle 1 is equipped with an internal combustion engine 2 and an AMT type automatic transmission 5 in a torque transmission path from the engine 2 to drive wheels (3), an engine controller 10 as an engine control means that issues torque requests to the engine 2, and an AMT controller 14 that controls the gear shifting operation of the automatic transmission 5 to a gear determined based on the engine speed and the torque request, and the clutch opening and closing operation linked thereto.

[0010] The vehicle 1 also has a brake control device 20 (including a brake controller and a brake actuator (hydraulic actuator)) that can individually control the braking force of the brakes 33 of the left and right front wheels 3 and the brakes 44 of the left and right rear wheels 4, a brake pedal 21, a hydraulic pressure sensor 22, wheel speed sensors 23 of the left and right front wheels 3, and wheel speed sensors 24 of the left and right rear wheels 4, and is equipped with a brake system that constitutes an ABS / vehicle behavior stabilization device.

[0011] Furthermore, the vehicle 1 is equipped with a preceding vehicle detection means 11 which constitutes an ACC system together with the ACC controller 12. The preceding vehicle detection means 11 has a function of detecting the presence of a preceding vehicle or an object (obstacle, structure) ahead of the host vehicle, such as a millimeter wave radar, a stereo camera, or a LIDAR, and can use one or more detection means capable of measuring the relative distance between the host vehicle and the preceding vehicle or obstacle.

[0012] The ACC controller 12 is configured to issue acceleration / deceleration commands to the engine controller 10 and the brake control device 20 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 23, 24, and to execute adaptive cruise control (constant speed driving / follow-up driving control / deceleration stop / restart control) compatible with all vehicle speed ranges.

[0013] That is, the brake control device 20 (brake controller) that receives a deceleration command from the ACC controller 12 issues a brake request (hydraulic pressure request) to the brake actuator, and controls the braking force of the brakes 33, 44 to control the vehicle speed. (torque requirement) The engine controller 10 receives 、 Torque Requirement Depending on By controlling the actuator output (throttle opening), the torque of the engine 2 is controlled, and the vehicle speed is controlled.

[0014] By the above control of the ACC controller 12, the vehicle 1 maintains a set vehicle speed and travels at a constant speed when there is no preceding vehicle, and when it catches up with the preceding vehicle, it travels following the preceding vehicle while maintaining a vehicle distance according to a predetermined vehicle distance time (time gap = vehicle distance / own vehicle speed) in accordance with the speed of the preceding vehicle. Furthermore, if the preceding vehicle decelerates and stops while following, or if the vehicle 1 catches up with a preceding vehicle that is decelerating and stopping, it decelerates and stops while securing a predetermined vehicle distance, and if the preceding vehicle starts moving within the predetermined time, it restarts to match it and continues following.

[0015] The engine controller 10, AMT controller 14, brake controller of the brake control device 20, and ACC controller 12 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 calculation results, a CPU for performing calculation processing, a communication I / F, etc., and are connected to a preceding vehicle detection means 11 and a group of sensors including an inclination sensor 13 described below via an in-vehicle network (CAN, etc.) so as to be able to communicate with each other.

[0016] The vehicle 1 according to the embodiment of the present invention includes an inclination sensor 13 as an inclination detection means for detecting the gradient of the road surface. As the inclination sensor 13, an inclination sensor that detects the inclination of the vehicle 1 in the longitudinal direction based on the gravitational acceleration, an acceleration sensor, a multi-axis inertial sensor, or the like can be used.

[0017] (Improved deceleration / stop control) The cruise control system according to the present invention is characterized by deceleration / stop control in the ACC function implemented by the ACC controller 12, and executes deceleration / stop control taking into consideration the road surface gradient detected by the inclination sensor 13 in addition to the detection information from the preceding vehicle detection means 11. The improved deceleration / stop control will be described below with reference to Figs. 2 to 4.

[0018] First, as shown in FIG. 2(a), when the preceding vehicle 6 detected by the preceding vehicle detection means 11 is being followed within a predetermined set inter-vehicle time Xg, if the preceding vehicle 6 decelerates and stops, or if the vehicle catches up with the preceding vehicle 6 that is decelerating and stopping, a deceleration command is issued from the ACC controller 12.

[0019] Then, as shown in FIG. 3, the brake fluid pressure increases due to the brake request and braking force begins to act, while at the same time the torque request of the engine 2 becomes zero, the clutch of the automatic transmission 5 is released, the drive torque transmitted to the drive shaft becomes zero, and the vehicle 1 begins to decelerate at a predetermined deceleration according to the brake request (FIG. 4, step 100).

[0020] Then, as shown in FIG. 2(b), in the case of a slope where the inclination sensor 13 detects a road gradient of a predetermined threshold value (e.g., 3%) or more just before the vehicle 1 stops with a predetermined distance Xd between it and the preceding vehicle 6 (FIG. 4, step 101, YES), a required value of creep torque (torque for stopping the vehicle 1 against the road gradient) for compensating for the road gradient is calculated.

[0021] Next, when the vehicle 1 reaches a first vehicle speed Va (e.g., 3 km / h) just before coming to a stop (point a in FIG. 3; FIG. 4, step 102, YES), a torque request is issued to the engine 2 based on the above-mentioned request value (FIG. 4, step 103), and at the same time, an engagement force is applied to the clutch of the automatic transmission 5, and torque begins to be transmitted to the drive shaft.

[0022] Torque transmission is started together with such torque request and clutch engagement, but when the vehicle further decelerates due to the braking force and reaches a second vehicle speed Vb (e.g., 2 km / h) (point b in FIG. 3, FIG. 4, step 104, YES), the brakes are temporarily reduced in pressure (point b in FIG. 3, FIG. 4, step 105).

[0023] Due to the increase in drive torque and the reduction in brake pressure, the deceleration of the vehicle 1 is mitigated, and when the vehicle 1 reaches a third speed Vc (e.g., 1 km / h) that can be regarded as being substantially stopped (point c in FIG. 3; FIG. 4, step 106, YES), the brake pressure is increased (FIG. 4, step 107), and the vehicle 1 comes to a complete stop (step 108, YES) and the brake pressure is maintained even after the increase in brake pressure is completed (step 109). When a predetermined time has elapsed after the vehicle has stopped, the torque request becomes zero, and at the same time the clutch of the automatic transmission 5 is released (FIG. 4, step 110).

[0024] On the other hand, if the road surface gradient detected by the inclination sensor 13 is less than a predetermined threshold value (e.g., 3%) on a flat road just before the vehicle 1 stops with a predetermined distance Xd between it and the preceding vehicle 6 (FIG. 4, step 101, NO), the brakes are temporarily reduced (FIG. 4, step 112) when the vehicle speed Vd (e.g., 1.5 km / h) is reached (FIG. 4, step 111, YES), and then, when the vehicle 1 reaches a third speed Vc (e.g., 0.5 km / h) that can be regarded as a substantial stopped state (FIG. 4, step 113, YES), the brakes are increased (FIG. 4, step 107), and the vehicle 1 is brought to a complete stop (steps 108-109).

[0025] 4, if the deceleration command from the ACC controller 12 is stopped due to the preceding vehicle 6 starting to move, etc., in steps 123, 125, and 127 when it is determined in step 101 that there is an inclination, or in steps 122 and 124 when it is determined that there is no inclination, the deceleration stop control ends at that point and the control returns to ACC control. Also, if the preceding vehicle 6 starts to move after the deceleration stop, the control returns to ACC control by stepping on the accelerator pedal or operating a predetermined button.

[0026] (Brake operation during deceleration / stop control) Also, as shown in FIG. 5, in step 103 of FIG. 4, after a torque request corresponding to the road surface gradient is issued and the clutch of the automatic transmission 5 is engaged (for example, at point b' in FIG. 3), if the driver depresses the brake pedal 21 and a brake pedal ON signal is detected (step 131), the torque request immediately becomes zero in order to avoid engine stall, and at the same time, the clutch of the automatic transmission 5 is released (step 110).

[0027] In this case, it may be determined that the control by the ACC controller 12 has been overridden by the driver's operation of the brake pedal, and the HMI device may notify the driver that ACC has been released and transition to manual driving, or ACC control may be continued by operating the designated button or accelerator pedal, as described above.

[0028] (Action and Effects) As described above in detail, the driving control system of the present invention is configured to request a predetermined torque in parallel with the control to temporarily reduce and then increase the braking force if a road gradient equal to or greater than a predetermined threshold is detected when the vehicle 1 reaches a first vehicle speed Va, at which it is determined that the vehicle is about to stop. This makes it possible to stop the vehicle with torque applied in the uphill direction while suppressing pitching when decelerating and stopping, and provides the same feeling of deceleration and stopping as on a flat road, even on uphill roads, without the sensation of the vehicle lurching backwards.

[0029] In particular, after a predetermined torque request is made at a first point in time when the vehicle has reached a first vehicle speed Va, which is judged to be about to stop, control is started to temporarily reduce the braking force and then increase the pressure at a second point in time when the vehicle has reached a second vehicle speed Vb which is smaller than the first vehicle speed Va, thereby ensuring that torque is applied before the vehicle is stopped.

[0030] Furthermore, in a vehicle 1 equipped with an AMT type automatic transmission 5, the clutch is engaged at the same time as a torque request, but the engagement force is added to the clutch just before the braking force is increased, and the time for generating driving force (creep torque) is very short, so the burden on the clutch is small and there is no effect on the clutch due to heat generation.

[0031] The torque requirement when a road gradient equal to or greater than a predetermined threshold is detected is preferably a torque requirement equivalent to a torque for stopping the vehicle against the road gradient. However, it is not necessary for the requirement value to be strict balance, and a compensation torque requirement value is set according to the road gradient within a range that does not result in an excessive torque requirement. For example, it is advantageous to set the compensation torque to be larger in proportion to the road gradient, and to prepare compensation torque requirement values ​​corresponding to the road gradient as a look-up table.

[0032] In addition, the acceleration of the vehicle 1 and the slip ratio of the wheels can be obtained from the wheel speeds detected by the wheel speed sensors 23, 24, the road surface friction coefficient (road surface μ) can be estimated, and the compensation torque requirement value (look-up table) can be switched depending on the road surface conditions.

[0033] In the above embodiment, a case has been described in which the clutch of the automatic transmission 5 is released at the same time as the torque request is zero and is engaged at the same time as the torque request is made in the vehicle 1 equipped with an AMT type automatic transmission 5 in the torque transmission path from the engine 2 to the drive wheels (3). However, the present invention can also be implemented in vehicles equipped with other types of automatic transmissions, such as a CVT type, which has a weaker force than the force that balances the inclination.

[0034] Furthermore, in the above embodiment, the present invention has been described as being implemented in a vehicle 1 having an ACC function, but it may also be implemented in a vehicle having an automatic lane keeping function (automatic driving function) that includes the ACC function.

[0035] 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]

[0036] 1 vehicle 2 Engine 5. Automatic transmission 10 Engine Controller 11. Means for detecting preceding vehicle 12 ACC Controller 13 Tilt Sensor 14 AMT Controller 20 Brake control device 21 Brake pedal 22 Fluid pressure sensor 23,24 Wheel speed sensor 33,44 Brake

Claims

1. A vehicle travel control device comprising: an engine control means for controlling an engine in response to a torque request; a brake control means for controlling a braking force in response to a brake request; an inclination detection means for detecting a road surface inclination; and a preceding vehicle detection means for detecting a preceding vehicle, A vehicle control system having a function of decelerating and stopping a preceding vehicle detected by the preceding vehicle detection means while maintaining a predetermined vehicle distance, and configured to implement pitching suppression control for temporarily reducing the braking force and then increasing the braking force immediately before the preceding vehicle stops, a vehicle driving control device configured to make a predetermined torque request in accordance with the pitching suppression control when the inclination detection means detects a road surface gradient equal to or greater than a predetermined threshold value when the vehicle reaches a first vehicle speed at which it is determined that the vehicle is about to stop, and the first vehicle speed is greater than the vehicle speed at which braking force is increased in the pitching suppression control.

2. 2. The vehicle driving control device according to claim 1, wherein, when the preceding vehicle decelerates to a stop, a torque request is set to zero and a predetermined brake request is made in order to decelerate and stop the host vehicle, and at a first point in time when the host vehicle reaches the first vehicle speed, which is determined to be the point at which the host vehicle is about to stop, if the inclination detection means detects a road surface gradient of a predetermined threshold or more, a predetermined torque request is made, and at the same time or at a second point in time when the host vehicle reaches a second vehicle speed which is slower than the first vehicle speed, pitching suppression control is started to temporarily reduce the braking force and then increase it.

3. 3. The vehicle driving control device according to claim 1, wherein the torque request when a road surface gradient equal to or greater than the predetermined threshold value is detected is a torque request equivalent to a torque for stopping the vehicle against the road surface gradient.

4. 4. The vehicle driving control device according to claim 1, further comprising: a torque request when a road surface gradient equal to or greater than the predetermined threshold is detected, the torque request being set to zero after a predetermined time has elapsed since the host vehicle came to a stop.

5. 5. The vehicle driving control device according to claim 1, further comprising: a brake pedal operated after the torque request is made when a road gradient equal to or greater than the predetermined threshold is detected; and the torque request is set to zero when the brake pedal is operated after the torque request is made when a road gradient equal to or greater than the predetermined threshold is detected.

6. An automatic transmission (AMT) is provided in a torque transmission path from the engine to the drive wheels, 4. The vehicle driving control device according to claim 2 or 3, wherein when the preceding vehicle decelerates and stops, the clutch of the automatic transmission is released simultaneously with the torque request becoming zero, and when a road surface gradient equal to or greater than a predetermined threshold is detected by the inclination detection means at the first point in time, the clutch is engaged simultaneously with the predetermined torque request.

7. 7. The vehicle driving control device according to claim 6, wherein the torque request when a road gradient equal to or greater than the predetermined threshold is detected is set to zero after a predetermined time has elapsed since the host vehicle came to a stop, and the clutch is released at the same time.

8. 8. The vehicle driving control device according to claim 6, further comprising: a torque request command for requesting a torque of at least one of the first torque and the second torque ...

9. The vehicle driving control device according to any one of claims 1 to 8, characterized in that, when the detection value of the inclination detection means reaches the first vehicle speed at which it is determined that the vehicle is about to stop, if the detection value of the inclination detection means is less than a predetermined threshold value, a torque request is maintained at zero.

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