Vehicle driving control device

Abstract

To provide a travel control device for a vehicle which is advantageous for suppressing heat generation and wear of a clutch in the case of ultra low speed following-travelling of an AMT vehicle.SOLUTION: A travel control device (10) for a vehicle includes a clutch (3) for transmitting output of an engine to a transmission mechanism (4), an AMT controller (40) for controlling a transmission actuator and a clutch actuator according to a vehicle speed and an engine speed, and executing gear stage change operation of the transmission mechanism, and an engine controller (20) for controlling the engine according to an acceleration / deceleration command, wherein when a preceding vehicle traveling on an own vehicle traveling line at a vehicle speed lower than a predetermined vehicle speed exists, the travel control device has a function of issuing an acceleration / deceleration command so as to perform following and travelling as to maintain set inter-vehicle time with the preceding vehicle, and executes such control as to intermittently disengage the clutch at a predetermined cycle (Ta), in the case of travelling while following the preceding vehicle which can travel in the clutch engagement state and travels at speed lower than the lowest vehicle speed (Va).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle cruise control device, and more particularly to a vehicle cruise control device equipped with an AMT type automatic transmission. [Background technology]

[0002] An automated manual transmission (AMT) type automatic transmission is known, which is equipped with a clutch that transmits engine output to a transmission mechanism and automatically performs gear shifting and clutch operation (see, for example, Patent Document 1). Such automatic transmissions have the advantages of high power transmission efficiency and excellent fuel economy.

[0003] Meanwhile, adaptive cruise control (ACC) has been put into practical use, which allows the vehicle to travel at a constant speed when there is no preceding vehicle in the vehicle's lane, and follows the preceding vehicle while maintaining a set intervehicle time when there is a preceding vehicle in the vehicle's lane traveling at a speed slower than the set speed. This system has been expanded to become an ACC that can be used at all vehicle speeds, including following a vehicle in front that is traveling at a low speed due to traffic congestion, etc., and slowing down, stopping, and starting again. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6245109 Summary of the Invention [Problem to be solved by the invention]

[0005] In vehicles equipped with an AMT (Automatic Manual Transmission), there is a minimum vehicle speed at which the clutch can be engaged. Therefore, when following a preceding vehicle traveling at an extremely low speed below the minimum vehicle speed, it has been considered to maintain the clutch in a partially engaged state without fully engaging it. However, if the partially engaged state continues, there are concerns about heat generation and wear of the clutch.

[0006] The present invention has been made in consideration of the above-described circumstances, and its purpose is to provide a vehicle driving control device that is advantageous in suppressing heat generation and wear of the clutch when an AMT vehicle is following at extremely low speeds. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides: a clutch that transmits engine output to a transmission mechanism; a clutch actuator that engages and disengages the clutch; a speed change actuator that changes the gear stage of the speed change mechanism; an AMT controller that controls the shift actuator and the clutch actuator in accordance with a vehicle speed and an engine rotation speed to change the gear position of the shift mechanism; an engine controller that controls the engine in response to an acceleration / deceleration command; A vehicle driving control device comprising: When there is a preceding vehicle traveling in the vehicle's lane at a speed slower than a set speed, the vehicle has a function of issuing an acceleration / deceleration command to the preceding vehicle so as to follow the preceding vehicle while maintaining a set inter-vehicle time, The vehicle driving control device is characterized in that it is configured to execute control to intermittently release the clutch when following a preceding vehicle traveling at a speed less than the minimum vehicle speed at which the clutch can be engaged. [Effects of the Invention]

[0008] As described above, the vehicle driving control device of the present invention is configured to execute control to intermittently release the clutch at a predetermined period when following a preceding vehicle that is traveling at a speed below the minimum vehicle speed at which the clutch can be driven with the clutch engaged. This has the advantage that the continuation of the half-clutch state is avoided, and the AMT vehicle can be driven at extremely low speeds while suppressing heat generation and wear of the clutch. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a block diagram showing a vehicle cruise control system. [Figure 2] 4 is a time chart showing clutch control according to the first embodiment of the present invention. [Figure 3] 6 is a time chart showing clutch control according to a second embodiment of the present invention. [Figure 4] 3 is a flowchart showing a travel control according to an 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. In FIG. 1, a vehicle 1 includes an internal combustion engine 2 and an automatic transmission 4 via a clutch 3 in a torque transmission path from the engine 2 to drive wheels (6).

[0011] The clutch 3 is provided with a clutch actuator (not shown) that performs the engagement / disengagement operation, and the engagement rate and engagement / disengagement speed of the clutch 3 can be controlled by controlling the operating stroke and operating speed of the clutch actuator.

[0012] For example, the clutch 3 includes a clutch disc that is spline-engaged to the input shaft of the automatic transmission 4 so as to be axially slidable but non-rotatable, and a clutch spring (diaphragm spring) that biases the clutch disc via a pressure plate. When the clutch actuator is in an inoperative state, the clutch disc is pressed against a flywheel connected to the crankshaft of the engine 2 by the bias of the clutch spring, and power from the engine 2 can be transmitted from the crankshaft to the automatic transmission 4.

[0013] When the clutch actuator operates, the release bearing is pressed via the clutch lever in accordance with the stroke, causing the clutch disc to move away from the flywheel against the bias of the clutch spring, thereby cutting off the transmission of power from the engine 2. Also, the clutch 3 can be placed in a half-clutch state in which the power of the engine 2 is partially transmitted in accordance with the contact pressure (engagement rate) provided by the operating stroke of the clutch actuator.

[0014] Furthermore, by controlling the operating speed of the clutch actuator, it is possible to control the engagement and release speeds of the clutch 3. For example, when a hydraulic actuator is used as the clutch actuator, it is possible to control the operating speed of the hydraulic actuator by controlling the flow rate of hydraulic oil supplied to the hydraulic actuator, and it is also possible to control the engagement rate provided by any stroke of the hydraulic actuator by maintaining hydraulic pressure at that stroke.

[0015] The automatic transmission 4 is configured as an AMT type automatic transmission having an MT type shifting mechanism, for example, a parallel gear type shifting mechanism with a constant mesh synchromesh, and a shift actuator that performs gear stage operation, and is equipped with an AMT controller 40 that performs shifting operations according to the driving conditions of the vehicle 1.

[0016] 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 changes including clutch release, gear change, and clutch engagement. Note that hydraulic actuators are used as the select actuator and shift actuator, and an electric pump that supplies hydraulic pressure to them as well as the clutch actuator, a hydraulic circuit, an accumulator, a solenoid valve, and other components are mounted as a unit.

[0017] 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.

[0018] For example, when the D range is selected, if the AMT controller 40 determines that a gear change (upshift / downshift) is necessary due to an acceleration request / deceleration request or a change in road gradient while driving in a gear position determined by driving conditions such as vehicle speed, engine speed, and torque (driving resistance), the AMT controller 40 performs the gear change (upshift / downshift), transmits driving torque to the automatic transmission 4 according to the engagement rate of the clutch 3, and when the series of gear change operations is completed, the engine returns to control by the engine controller 20.

[0019] 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.

[0020] The vehicle 1 having the above-described basic configuration is equipped with preceding vehicle detection means 11, which 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, monocular camera, stereo camera, LIDAR, etc., that have the function of detecting the presence of preceding vehicles or objects (obstacles, structures) 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.

[0021] The ACC controller 10 is configured to issue acceleration / deceleration commands 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 driving / follow-up driving control / deceleration / stop / restart control) compatible with all vehicle speed ranges.

[0022] That is, the brake controller 30 (brake controller) that 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. Also, the engine controller 20 that receives an acceleration / deceleration command from the ACC controller 10 issues a torque request to the engine 2 and controls the actuator output (throttle opening) to control the torque of the engine 2 and thus the vehicle speed.

[0023] Through the above control by the ACC controller 10, 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 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, if the preceding vehicle decelerates to a stop while following, or if the vehicle 1 catches up with a preceding vehicle that is decelerating to a stop, it decelerates to a stop while maintaining a predetermined inter-vehicle distance, and if the preceding vehicle starts moving within the predetermined time, it restarts to match it and continues following.

[0024] 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 via an in-vehicle network (e.g., CAN) to be able to communicate with a group of sensors including a preceding vehicle detection means 11 and an inclination sensor 12.

[0025] (ACC ultra-low speed tracking control) As already mentioned, a vehicle 1 equipped with an AMT automatic transmission 4 has a minimum vehicle speed at which it can travel with the clutch 3 engaged. That is, the minimum vehicle speed at which it can travel in first gear, where the reduction ratio is greatest, without stalling the engine, is 7 to 9 km / h, depending on the road gradient and load weight. Even in an AMT vehicle, pseudo-creep driving can be performed by maintaining the clutch in a half-clutch state without fully engaging it, but continuous creep driving is not desirable due to heat generation and wear of the clutch.

[0026] On the other hand, vehicles with automatic transmissions other than AMT and vehicles capable of EV driving may travel at extremely low speeds below the minimum vehicle speed. Therefore, the cruise control device according to the present invention is configured to transition to the following extremely low speed following control when performing ACC following of a preceding vehicle traveling at an extremely low speed below the minimum vehicle speed due to traffic congestion or the like.

[0027] 2, low-speed running below the minimum vehicle speed Va with the clutch engaged is achieved by executing control to intermittently release the clutch 3 at a predetermined cycle. In this first embodiment, by repeating at a predetermined cycle αa, which is in the half-clutch region where the clutch engagement rate is less than 100%, and an open state where the engagement rate is 0%, the half-clutch state is prevented from continuing, thereby avoiding heat generation and wear of the clutch, and low-speed running below the minimum vehicle speed Va is possible with the partial and intermittent transmission torque due to the intermittent engagement rate αa.

[0028] The transmission torque due to the intermittent engagement rate αa of the clutch 3 is given by the period (Ta) and / or duty ratio (a / Ta) at which the clutch 3 is intermittently released. That is, in the extremely low speed tracking control at which the engine torque is reduced to the minimum level and the vehicle speed is less than the minimum vehicle speed Va, the period and / or duty ratio at which the clutch 3 is intermittently released are controlled so that the averaged vehicle speed becomes the target vehicle speed.

[0029] In this case, in the first embodiment shown in Figure 2, in addition to the fact that the engagement rate αa of the intermittent engagement state is kept within the half-clutch region, the vehicle speed is leveled out by the inertial force acting on the vehicle, so even if the engagement time a1 corresponding to the engagement speed of the clutch 3 and the release time a3 corresponding to the release speed of the clutch 3 are approximately the same, there is almost no impact when the clutch is engaged, and extremely low-speed following driving is possible at an averaged vehicle speed.

[0030] On the other hand, in the second embodiment shown in Figure 3, when the clutch 3 is engaged αb, it is not in the half-clutch region but is in a fully engaged state with an engagement rate of 100%, which further improves the effect of suppressing heat generation and wear of the clutch, and the engagement time b1 corresponding to the engagement speed of the clutch 3 is made longer than the release time b2 corresponding to the release speed of the clutch 3, so that the impact at the time of engagement is reduced by the gradual engagement.

[0031] In this second embodiment, the torque transmission efficiency αb when the clutch is engaged is higher than in the first embodiment, so by reducing the time b2 when the engagement rate is 100% and the duty ratio (b / Tb) and increasing the proportion of the clutch release period b0, it is possible to achieve a target vehicle speed similar to that of the first embodiment.

[0032] The extremely low speed travel control according to the first and second embodiments, i.e., the control of intermittently engaging / disengaging the clutch 3 in first gear and simultaneously intermittently requesting a minimum torque from the engine 2 in synchronization therewith, may be prepared in the AMT controller 40 as an extremely low speed travel mode (for example, virtual 0.5 speed), and may be executed by shifting down to this extremely low speed travel mode when a deceleration command below the minimum vehicle speed Va is issued from the ACC controller 10.

[0033] Alternatively, the ACC controller 10 can be configured to prepare an extremely low speed deceleration command (intermittent torque request) corresponding to an extremely low speed driving mode, and when the target vehicle speed becomes less than the minimum vehicle speed Va and an extremely low speed deceleration command (intermittent torque request) is issued, the AMT controller 40 executes intermittent clutch engagement / disengagement control, and in synchronization therewith, the engine controller 20 executes intermittent throttle control of the engine 2 corresponding to the torque request.

[0034] In this case, as the intermittent torque request alternates between torque request and no torque request, the engine controller 20 determines that "no torque request" means the vehicle is stopped (idling) and releases the clutch, and determines that "torque request" means the vehicle is restarting and begins to engage the clutch, so that such vehicle stop control can also be used to perform extremely low-speed driving control.

[0035] The flow of the ACC extremely low-speed following control described above is shown in Figure 4. In Figure 4, when the ACC function is activated while vehicle 1 is traveling and there is no preceding vehicle traveling at less than a set vehicle speed within a set inter-vehicle time ahead in the vehicle's travel lane, the ACC controller 10 issues an acceleration / deceleration command so that the vehicle speed of vehicle 1 is maintained at the set vehicle speed, the engine controller 20 controls the torque of engine 2 based on the acceleration / deceleration command, and the brake controller 30 controls the brakes during deceleration.

[0036] On the other hand, if the preceding vehicle detection means 11 detects a preceding vehicle traveling at less than the set vehicle speed, the ACC controller 10 issues an acceleration / deceleration command with the speed of the preceding vehicle as the target vehicle speed so that the set inter-vehicle time with the preceding vehicle is maintained, the engine controller 20 controls the torque of the engine 2 based on the acceleration / deceleration command, and the brake controller 30 controls the brakes during deceleration, transitioning to ACC following driving (step 100).

[0037] After transitioning to ACC following driving, when the gear stage of the vehicle 1 is shifted down to first speed due to deceleration of the preceding vehicle, the ACC controller 10 monitors whether the target vehicle speed for ACC following driving (vehicle speed of the preceding vehicle) is less than the minimum vehicle speed Va with the clutch engaged (step 110).If the target vehicle speed becomes less than the minimum vehicle speed Va due to traffic congestion or the like (step 110; YES), the system transitions to extremely low speed following control, in which the clutch 3 is intermittently released (step 111).

[0038] If the target vehicle speed becomes equal to or exceeds the minimum vehicle speed Va due to acceleration of the preceding vehicle or the like during execution of the ultra-low speed following control (step 112; YES), the ultra-low speed following control is terminated and normal ACC following driving is resumed (step 113).

[0039] Furthermore, if the preceding vehicle stops while the very low speed following control is being executed, vehicle 1 stops while maintaining the set inter-vehicle distance, and the very low speed following control ends. After that, when the preceding vehicle starts moving again, vehicle 1 starts moving again in first gear, but continues to monitor whether the target vehicle speed is below minimum vehicle speed Va until it becomes equal to or greater than minimum vehicle speed Va. If the vehicle speed of the preceding vehicle remains below minimum vehicle speed Va, the very low speed following control is executed to intermittently release clutch 3.

[0040] The minimum vehicle speed Va when the clutch is engaged also varies depending on the road inclination. When there is a significant downhill slope, extremely low-speed following can be achieved using brake control alone. However, on an uphill road with a significant uphill slope, the minimum vehicle speed Va decreases depending on the road inclination. Therefore, it is preferable to dynamically set the minimum vehicle speed Va depending on the road inclination. Furthermore, on an uphill road with a significant uphill slope, it is preferable to shorten the cycle at which the clutch 3 is intermittently released depending on the road inclination.

[0041] In the above embodiment, the control for following a preceding vehicle at an extremely low speed below the minimum vehicle speed Va in the ACC following control has been described. However, the extremely low speed traveling control according to the present invention can also be implemented as a control for generating creep torque when starting on a slope in manual driving.

[0042] 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]

[0043] 1 vehicle 2 engines 3. Clutch 4. Automatic transmission 10 ACC controller 11. Means for detecting preceding vehicles 12 Inclination sensor 16,17 Wheel speed sensor 20 Engine Controller 30 Brake control device 36,37 Brakes 40 AMT Controller

Claims

1. a clutch that transmits engine output to a transmission mechanism; a clutch actuator that engages and disengages the clutch; a speed change actuator that changes the gear stage of the speed change mechanism; an AMT controller that controls the shift actuator and the clutch actuator in accordance with a vehicle speed and an engine rotation speed to change the gear position of the shift mechanism; an engine controller that controls the engine in response to an acceleration / deceleration command; A vehicle driving control device comprising: When there is a preceding vehicle traveling in the vehicle's lane at a speed slower than a set speed, the vehicle has a function of issuing an acceleration / deceleration command to the preceding vehicle so as to follow the preceding vehicle while maintaining a set inter-vehicle time, A vehicle driving control device characterized in that, when following a preceding vehicle traveling at a speed less than the minimum vehicle speed at which the vehicle can travel with the clutch engaged, the vehicle controls the clutch to be intermittently released repeatedly at a predetermined cycle, and the vehicle follows the preceding vehicle so that the averaged vehicle speed becomes a target vehicle speed.

2. 2. A vehicle driving control device according to claim 1, characterized in that the control of intermittently releasing the clutch is performed by repeating a half-clutch state in which the clutch has an engagement rate of less than 100% and an released state in which the clutch has an engagement rate of 0% at a predetermined cycle.

3. 2. The vehicle driving control device according to claim 1, wherein the control of intermittently releasing the clutch is performed by repeating an engaged state of the clutch with an engagement rate of 100% and a released state with an engagement rate of 0% at a predetermined cycle.

4. 4. The vehicle driving control device according to claim 2, wherein the control for intermittently disengaging the clutch is characterized in that an engagement speed of the clutch moving from the disengaged state to the half-clutch state or the engaged state is slower than a release speed of the clutch moving toward the disengaged state.

5. 5. The vehicle travel control device according to claim 1, wherein a cycle of the control for intermittently releasing the clutch is determined based on the speed of the preceding vehicle and the inclination of the road surface.

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