JP2005265176A - Running control device of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To intend to enhance driveability by assuring travelling performance in accordance with driver's intention in a running control device of a vehicle. <P>SOLUTION: A method includes a step of detecting vehicle following distance between a self-vehicle and a preceding former vehicle, a step of decelerating the self-vehicle by action of engine braking by shifting down an automatic transmission 13 of the self-vehicle and simultaneously maintaining low-speed stage after gear-shifting when the vehicle following distance becomes below proper value, a step of calculating deviation between current accelerator opening and accelerator opening required to steady travelling of the self-vehicle during selectively controlling the low-speed stage, a step of setting control time until the control is completed from the deviation of the accelerator opening, and a step of releasing to selectively control the low-speed stage after the control time is elapsed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a travel control device for a vehicle that controls a transmission of the host vehicle in accordance with an inter-vehicle distance between the host vehicle and a front vehicle.

  2. Description of the Related Art Conventionally, a technique for detecting a distance between an own vehicle and a preceding vehicle and controlling the vehicle speed so that the distance between the vehicles is maintained at a safe distance is known. Generally, when the inter-vehicle distance between the host vehicle and the preceding vehicle becomes shorter than the safe inter-vehicle distance, the transmission of the host vehicle is shifted down and the host vehicle is decelerated by engine braking. During this inter-vehicle distance control, This deceleration control is canceled when the driver operates the accelerator pedal.

  As such a technique, for example, there is a technique described in Patent Document 1 below. The vehicle travel control apparatus described in Patent Document 1 shifts when the accelerator opening time is a predetermined value or more when the driver operates the accelerator pedal during inter-vehicle distance control by shifting down the transmission. The down control is stopped to shift up, and the other shift stages are maintained at the current shift stage. Therefore, drivability can be improved by shifting up only when speed increase is really necessary.

JP 2000-318484 A

  In inter-vehicle distance control, when the host vehicle follows the front vehicle traveling ahead, if the inter-vehicle distance between the host vehicle and the front vehicle decreases, the transmission is shifted down to increase the engine brake of the host vehicle. Thus, the relative vehicle speed is reduced. After that, the driver of the vehicle may try to follow or overtake the previous vehicle, and depresses the accelerator pedal to accelerate. In general, when the driver wants to follow the vehicle ahead of him / her, the driver depresses the accelerator pedal once, and when the vehicle accelerates, the driver performs an operation to quickly return the accelerator pedal. Further, when the own vehicle wants to pass the preceding vehicle, the driver depresses the accelerator pedal for a certain time, and when the own vehicle accelerates and passes the preceding vehicle, the driver performs an operation to immediately return the accelerator pedal. That is, in overtaking, there is a demand for maintaining a low speed and accelerating for a certain period of time, but in following traveling, there is a demand for shifting up without maintaining the low speed for a long time.

  In the conventional vehicle travel control apparatus described above, when the driver opens the accelerator pedal for a predetermined time or more during the inter-vehicle distance control by the downshift, the low speed stage selection control is stopped. For this reason, if the driver depresses the accelerator pedal for more than a predetermined time during overtaking, the control is stopped and the vehicle shifts up, and the vehicle cannot obtain sufficient acceleration force, and the front vehicle is smooth. Can't overtake. On the other hand, if the predetermined time is set to be used for overtaking, the vehicle will continue to select a lower gear than necessary during follow-up, and the vehicle will generate a driving force that is greater than the driver's intention, allowing smooth overtaking. Can not.

  In addition, when the own vehicle approaches the preceding vehicle and travels following or passes, the driver steps various accelerators. In other words, the amount of depression of the accelerator pedal (accelerator opening) and the depression time (accelerator opening time) differ depending on the driving state of the vehicle, that is, the vehicle speed and the gear position, even in the follow-up traveling and the overtaking traveling. For this reason, there is a problem that drivability is deteriorated because it is not possible to accurately determine whether the vehicle is following or overtaking only with the accelerator opening or the accelerator opening time.

  The present invention is for solving such a problem, and an object of the present invention is to provide a vehicle travel control device that improves drivability by ensuring traveling performance according to the driver's intention. And

  In order to solve the above-described problems and achieve the object, a travel control device for a vehicle according to the present invention is based on the positional relationship between the vehicle and the front vehicle based on the positional relationship between the vehicle and the front vehicle. In the travel control device for a vehicle that executes control for selectively changing the shift speed of the vehicle to the low speed stage side, detects an instruction to increase the driving force of the own vehicle, and terminates the control for selective change to the low speed stage side. Driving force detection means for detecting a driving force required for steady running of the vehicle, and the low speed based on a deviation between a value corresponding to the driving force increase instruction and a driving force required for steady running detected by the driving force detection means Control time setting means for setting a control time until the control for selectively changing to the stage side is completed.

  In the vehicle travel control apparatus of the present invention, the control time is set to be longer as the deviation between the value corresponding to the drive force increase instruction and the drive force required for steady travel detected by the drive force detection means is larger. It is characterized by.

  In the vehicle travel control apparatus of the present invention, when the value corresponding to the driving force increase instruction is changed during the control to selectively change to the low speed stage side, the control time setting means increases the changed driving force. The control time is updated based on a value corresponding to the instruction.

  In the vehicle travel control apparatus of the present invention, the control time is canceled when the driving force increase instruction is canceled during the control to selectively change to the low speed stage side.

  In the vehicle travel control apparatus of the present invention, the control time setting means includes a current accelerator opening as a value corresponding to the driving force increase instruction and a steady accelerator opening determined from a driving force required for steady running. On the basis of the deviation, the control time is set until the control for selectively changing to the low speed stage is completed.

  Further, the vehicle travel control device of the present invention is a control for selectively changing the shift stage of the transmission to the low speed stage side based on the positional relationship with the front car so that the position of the host vehicle and the front car is appropriate. In the vehicle travel control device that detects the driving force increase instruction of the host vehicle and terminates the control to selectively change to the low speed stage side, the normal shift on the high speed stage side is performed after the selection change to the low speed stage side. Time calculating means for calculating a time until the distance between the host vehicle and the preceding vehicle becomes substantially zero when the return to the stage is determined, and until the distance calculated by the time calculating means becomes substantially zero Control end permitting means for permitting the end of the control when the time is longer than a predetermined time set in advance.

  Furthermore, the vehicle travel control apparatus according to the present invention is a control for selectively changing the shift stage of the transmission to the low speed stage side based on the positional relationship between the host vehicle and the front car so that the position between the host vehicle and the front car becomes appropriate. And a congestion degree detecting means for detecting the degree of congestion on the surrounding roads in the vehicle travel control device that terminates the control to detect the driving force increase instruction of the own vehicle and selectively change to the low speed stage side, and Control time setting means for setting a control time until the control to selectively change to the low speed stage based on the congestion degree detected by the congestion degree detection means is provided.

  In the vehicle travel control apparatus of the present invention, the control time is set longer as the congestion level detected by the congestion level detection means is larger.

  According to the vehicle travel control apparatus of the present invention, during the control for selectively changing the gear position of the transmission to the low speed side, based on the deviation between the value corresponding to the driving force increase instruction and the driving force required for steady traveling. Thus, the control time until the control to change the selection to the low speed stage is set, and the control to change the selection to the low speed stage is ended after the control time has elapsed, which corresponds to a driving force increase instruction. By using the deviation between the value and the driving force required for steady driving, the driving intended by the driver can be read appropriately, and driving performance according to the driver's intention is ensured to improve drivability. be able to.

  Further, according to the vehicle travel control apparatus of the present invention, after the shift stage of the transmission is selected and changed to the low speed stage side, the return from the low speed stage shift stage to the high speed stage normal shift stage is determined. Calculate the time until the distance between the vehicle and the preceding vehicle becomes approximately zero, and change the selection to the low speed stage when the time until this distance becomes approximately zero is longer than a preset predetermined time The control is terminated and this control is terminated.Therefore, considering the time until the distance between the host vehicle and the preceding vehicle becomes substantially zero, the speed change operation is repeated and the inter-vehicle distance is reduced. Control that changes frequently is not performed, and drivability can be improved by ensuring traveling performance according to the driver's intention.

  Furthermore, according to the vehicle travel control device of the present invention, during the control for selectively changing the shift stage of the transmission to the low speed stage side, the degree of congestion on the surrounding road is detected, and the low speed stage side is detected based on this congestion degree. Since the control time is set until the control to change the selection is completed, and the control to change the selection to the low speed stage is finished after the control time has elapsed, the driver can use the degree of congestion on the surrounding roads. Can be read appropriately, driving performance adapted to the driver's feeling can be ensured, and drivability can be improved.

  Embodiments of a vehicle travel control apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic configuration diagram illustrating a vehicle travel control apparatus according to a first embodiment of the present invention, FIG. 2 is a flowchart of control by the vehicle travel control apparatus according to the first embodiment, and FIG. 3 is a vehicle according to the first embodiment. FIG. 4A is a time chart of the follow-up control 1 by the vehicle travel control device of the first embodiment, and FIG. 4B is a follow-up by the vehicle travel control device of the first embodiment. 4 is a time chart of the overtaking control by the vehicle travel control apparatus according to the first embodiment, FIG. 5A is a graph showing the accelerator opening during the following traveling, and FIG. These are graphs showing the accelerator opening during overtaking traveling.

  In the vehicle travel control apparatus of the present embodiment, as shown in FIG. 1, an automatic transmission 13 having a torque converter 12 is connected to an engine 11 serving as an internal combustion engine. It is input to the automatic transmission 13 via the torque converter 12 and transmitted to the drive wheels via a differential gear and a drive shaft (not shown). Further, the automatic transmission 13 can automatically control the gear ratio according to the driving state of the vehicle by the hydraulic control device 14.

  The vehicle is provided with an electronic control unit (ECU) 15 that controls the engine 11, the automatic transmission 13, and the like. The ECU 15 performs comprehensive control of the engine 11 and the automatic transmission 13 (hydraulic control device 14). .

  That is, the vehicle is provided with an accelerator position sensor 21 that detects the amount of operation of the accelerator pedal (accelerator opening), and the detected accelerator opening is output to the ECU 15. An electronic throttle valve 23 is provided in the intake pipe 22 of the engine 11, and the electronic throttle valve 23 can be opened and closed by a throttle actuator 24. The ECU 15 drives the electronic throttle valve 23 by the throttle actuator 24 and controls the throttle opening so as to correspond to the accelerator opening. The intake pipe 22 is provided with a bypass passage 25 that bypasses the electronic throttle valve 23, and the bypass passage 25 controls intake air when the electronic throttle valve 23 is fully closed in order to control the idle speed of the engine 11. An idle speed control valve (ISC valve) 26 for controlling the amount is provided. A throttle position sensor 27 with an idle switch for detecting the fully closed state (idle state) of the electronic throttle valve 23 and the throttle opening is provided, and the detected idle signal and the throttle opening are output to the ECU 15.

  Further, an air flow sensor 28 for detecting the intake air amount is provided in the intake pipe 22 upstream of the electronic throttle valve 23, and the detected intake air amount is output to the ECU 15. Further, the engine 11 is provided with an engine speed sensor 29 for detecting the engine speed (engine speed) and a vehicle speed sensor 30 for detecting the traveling speed of the vehicle. The vehicle speed is output to the ECU 15. Further, the vehicle is provided with a shift position sensor 31 that detects the position of the shift lever operated by the driver, and the detected shift position and gear position are output to the ECU 15. The vehicle is provided with a brake switch 33 that detects the operation of the brake, and the detected brake signal is output to the ECU 15.

  Therefore, the ECU 15 determines the fuel injection amount, the injection timing, the ignition timing, and the like based on the operating state of the engine 11 such as the engine speed, the intake air amount, the throttle opening, and the like, and can control the injector, the ignition plug, and the like. it can. Further, the ECU 15 has a shift map, determines the shift stage of the automatic transmission 13 based on the throttle opening, the vehicle speed, and the like, and controls the hydraulic control device 14 to establish the determined shift stage. can do. Further, since the engine speed is appropriately changed in accordance with the change of the gear ratio at the time of shifting, the output control of the engine 11 can be performed as necessary.

  Further, in this embodiment, it is possible to detect the inter-vehicle distance between the host vehicle and the preceding preceding vehicle, perform a downshift based on the inter-vehicle distance, and control to increase the deceleration. In this case, the ECU 15 shifts down the automatic transmission 13 of the own vehicle to reduce the engine brake when the inter-vehicle distance obtained by dividing the inter-vehicle distance between the own vehicle and the preceding vehicle by the own vehicle speed becomes equal to or less than a predetermined value. When the driver gives an instruction to increase the driving force, such as operating the accelerator pedal, while the vehicle is decelerating due to the action and the gear on the low gear is selected, control to select the gear on the low gear To cancel.

  Therefore, the vehicle is provided with a laser radar sensor 34 as an inter-vehicle distance sensor that measures the inter-vehicle distance with the vehicle preceding the front (front vehicle), and the detected inter-vehicle distance with the front vehicle is output to the ECU 15. The The inter-vehicle distance sensor is not limited to the laser radar sensor 34, but may be one that uses radio waves or ultrasonic waves, or one that calculates inter-vehicle distance from images captured by a plurality of cameras.

  In this embodiment, the ECU 15 detects a driving force necessary for steady running of the host vehicle, for example, an accelerator opening (throttle opening), during the execution of the control for selecting the above-described low speed gear. (Driving force detection means) and calculate a value corresponding to an instruction to increase the driving force, for example, the deviation between the current accelerator opening (throttle opening) and the accelerator opening (throttle opening) required for steady running Then, based on the deviation of the accelerator opening, a control time is set (control time setting means) from when the control to select the low-speed gear side is executed to when the control is released after the control release determination is made. When the control time has elapsed, the control for selecting the low speed gear is canceled.

  Specifically, in this embodiment, the deviation between the current accelerator opening and the accelerator opening necessary for steady driving and the change state of the deviation are continuously monitored in real time, and the vehicle follows the front vehicle. Whether the vehicle is in a driving state where the host vehicle is overtaking the preceding vehicle. For follow-up driving, the control time is set short, the low-speed selection control is stopped in a short time to enable shift up, and for overtaking driving, the control time is set long and the driving force required for overtaking is set. Is secured for a predetermined time to enable smooth overtaking operation.

  In general, in the case of driving in which the host vehicle follows the front vehicle, as shown in FIG. 5-1, the driver immediately depresses the accelerator pedal and accelerates the host vehicle. There is a tendency to perform operations such as returning the pedal. When the vehicle overtakes the preceding vehicle, as shown by the dotted line in FIG. 5-2, the driver depresses the accelerator pedal to accelerate the vehicle, and then keeps this state for a certain period of time. When overtaking a car, there is a tendency to gradually return the accelerator pedal. In this follow-up operation and overtaking operation, as shown in FIGS. 5A and 5B, the accelerator opening increases as the vehicle speed increases, and the accelerator opening increases as the shift speed increases. It can be predicted. However, there are cases where the two pedals are slowly depressed without first depressing the accelerator pedal from the beginning.

  As described above, the vehicle travel control apparatus of the present embodiment detects a deviation between the current accelerator opening and the accelerator opening necessary for steady running in real time, and based on this accelerator opening deviation. By determining the driving state of the host vehicle, it is possible to reliably determine whether the vehicle is following operation or overtaking operation. And the control time corresponding to each driving | running state is set.

  The control time setting method uses, for example, the following Table 1. Here, the accelerator opening is obtained by dividing the depression angle by the full opening angle, and is displayed as a percentage (%). Further, the deviation of the accelerator opening is obtained by subtracting the accelerator opening in steady running from the current accelerator opening. In Table 1, if the accelerator opening deviation is 10% or less, the control time is set to 2 seconds. If the deviation is larger than 10% and 20% or less, the deviation is larger than 20% in 3 seconds. If it is 30% or less, it is set to 4 seconds, and if the deviation is larger than 30%, it is set to 6 seconds.

  In addition, the above-mentioned steady running of the vehicle is a driving state in which the driving force of the vehicle and the running resistance are balanced on a running road without a gradient, and the state where the driver has depressed the accelerator pedal for a predetermined amount is maintained. This refers to a traveling state in which the vehicle speed does not change. The driving force can be obtained from engine performance, gear position, etc., and the running resistance can be obtained from vehicle air resistance, road surface friction coefficient, vehicle weight, etc., so when this driving force and running resistance are balanced The throttle opening, that is, the accelerator opening is the driving force required for steady running. In the running experiment, the steady running of the vehicle may be reproduced for each vehicle speed and gear position, and the throttle opening at this time may be obtained and stored as a map.

  Here, the traveling control by the vehicle traveling control apparatus of the present embodiment will be described based on the flowchart of FIG.

  In the vehicle travel control, as shown in FIG. 2, in step S11, the ECU 21 determines whether or not an execution condition for executing the downshift control is satisfied. Here, it is determined that the downshift execution condition is satisfied when the accelerator pedal is in the OFF state and the inter-vehicle time is smaller than a predetermined value set in advance. Here, the OFF state of the accelerator pedal can be determined by an idle signal from the throttle position sensor 27 with an idle switch. That is, in an idle state where the driver does not depress the accelerator pedal, an idle ON signal is output, and the ECU 15 recognizes the accelerator pedal OFF state in response to the idle ON signal. The inter-vehicle time is the time obtained by dividing the inter-vehicle distance between the current host vehicle and the preceding vehicle by the own vehicle speed, and how many hours (actually, how many seconds) the host vehicle reaches the previous vehicle position. It ’s time. That is, the driver's intention to decelerate is confirmed based on the accelerator pedal being in an OFF state, and it is confirmed that the inter-vehicle distance is not maintained due to a decrease in the inter-vehicle time.

  The determination of the accelerator pedal OFF state is not limited to the idle ON signal, but may be determined based on the accelerator opening detected by the accelerator position sensor 21. That is, if the current accelerator opening is smaller than the accelerator opening for generating a driving force smaller than the running resistance of the host vehicle, it may be determined that the accelerator pedal is in the OFF state. Further, the collision time may be used instead of the inter-vehicle time. The collision time is the time between the current distance between the vehicle and the previous vehicle divided by the relative speed between the vehicle and the previous vehicle. It is time to collide with the previous car.

  In step S11, if the downshift execution condition is satisfied, the ECU 21 proceeds to step S12 and executes downshift. That is, the ECU 15 waits for the downshift execution condition to be satisfied, determines to shift down the shift speed of the automatic transmission 13 from, for example, the fourth speed to the third speed, and establishes the determined shift speed. The hydraulic control device 14 is controlled. In other words, downshift control is executed, and control (low speed stage selection control) is performed in which the low speed stage (third speed) after shifting is maintained.

  In step S13, after this downshift is executed, the accelerator pedal is turned on. That is, when the host vehicle decelerates due to an increase in engine braking force due to a downshift and the relative vehicle speed with respect to the preceding vehicle decreases, the driver's intention to accelerate is confirmed by determining the ON state of the accelerator pedal. It should be noted that the ON state of the accelerator pedal may be determined by an idle signal from the throttle position sensor 27 with an idle switch, similarly to the above-described accelerator pedal OFF state. That is, when the driver depresses the accelerator pedal, the idle OFF signal is output, and the ECU 15 recognizes the accelerator pedal ON state in response to the idle OFF signal. This determination is not limited to the idle signal, and may be determined based on the accelerator opening detected by the accelerator position sensor 21.

  If the accelerator pedal ON state is not determined in step S13, the low speed stage selection control is continued. If the accelerator pedal ON state is determined, the process proceeds to step S14, where the return timer is started. Let In step S15, the accelerator opening P0 necessary for steady running of the host vehicle is calculated at the current vehicle speed and gear position. As a calculation method of the accelerator opening P0, as described above, the accelerator opening when the driving force and the running resistance in the steady running are balanced is obtained by calculation, or data obtained in advance through a running experiment is stored. You may ask for it from the map. Then, in step S16, a deviation DP between the current accelerator opening P and the accelerator opening P0 necessary for steady running is calculated. In step S17, the low speed stage is calculated based on the accelerator opening deviation DP. The control time from when the selection control release command is received until this control is completed, that is, the return timer time is calculated according to Table 1.

  In step S18, it is determined whether or not the return timer count time (control time) that has been set has been exceeded, that is, whether or not this return timer time has elapsed. If the return timer time has not yet elapsed, it is checked in step S19 whether the accelerator pedal is turned off. If the accelerator pedal has already been returned and the accelerator pedal is in the OFF state, the return is made in step S20. After resetting the timer, the process returns to step S13 to wait for the accelerator pedal to be turned on again.

  On the other hand, if it is determined in step S19 that the accelerator pedal is not in the OFF state, the process returns to step S15, where the accelerator opening P0 necessary for steady running is calculated again, and the current accelerator opening P is determined in step S16. A deviation DP from the accelerator opening P0 necessary for steady travel is calculated, and a control time, that is, a return timer time is calculated from Table 1 based on the accelerator opening deviation DP in step S17. At this time, the deviation DP of the accelerator opening increases or decreases due to a change in the accelerator pedal depression amount (accelerator opening) by the driver, so that the return timer time is updated.

  In step S18, it is determined again whether the count time of the return timer exceeds the return timer time, that is, whether the return timer time has elapsed. If the return timer time has not yet elapsed, the process proceeds to step S19, and the same processing as described above is performed. On the other hand, if the return timer time has elapsed in step S18, the process proceeds to step S21, the low speed stage selection control is canceled to enable upshifting, and the normal gear stage control is executed. That is, the ECU 15 controls the automatic transmission 13 by the hydraulic control device 14 based on the throttle opening, the vehicle speed, and the like.

  Such traveling control by the vehicle traveling control apparatus of this embodiment will be described with reference to the time chart of FIG.

  As shown in FIG. 3, when the accelerator pedal is fully closed (OFF) at time t0 and the inter-vehicle time becomes smaller than a predetermined value and the downshift execution condition is satisfied, the downshift control and the low speed stage selection control are started. The That is, a shift command for shifting down the shift speed from n (for example, 4th speed) to n-1 (for example, 3rd speed) is output at time t1, and the input shaft speed of the automatic transmission 13 increases at time t1. The shift is started, the shift is completed at time t2, and the downshift control ends. However, even when the downshift control is completed, the low speed selection control is continued as it is so that the low speed (third speed) after the shift is maintained.

  When the accelerator pedal is depressed at the time t3 due to the driver's intention to accelerate, the input shaft rotational speed increases. When the accelerator pedal is determined to be in the ON state, the return timer is activated at the time t3. During this time, based on the deviation DP of the accelerator opening, a control time (time between t3 and t4) from when it is determined to cancel the low speed stage selection control until this control is terminated is obtained. When the control time elapses at time t4, the return timer is reset, the low speed stage selection control is terminated, and the upshift control is started. That is, at time t4, a shift command for shifting up the shift stage from n-1 to n is output, at time t5, the input shaft rotational speed of the automatic transmission 13 is lowered and the shift is started, and at time t6, the shift is completed. Then, the upshift control ends.

  Here, a specific example of the travel control by the vehicle travel control device described above will be described based on the time charts of FIGS. 4-1 to 4-3. In FIGS. 4A to 4C, the solid line represents the current accelerator opening, and the dotted line represents the accelerator opening for steady travel.

  In the follow-up control 1 by the vehicle travel control apparatus of the present embodiment, as shown in FIG. 4A, when the accelerator pedal is depressed (ON state) during the low speed stage selection control, the return timer starts (time = 0), and a return timer time (control time) is obtained based on the deviation DP between the current accelerator opening P and the steady travel accelerator opening P0. In this case, the return timer time is initially set to 4 seconds. However, since the return timer time is updated in real time, if the accelerator pedal is returned before the return timer count time exceeds 4 seconds, the return timer time is updated from 4 seconds to 3 seconds and 2 seconds. . Therefore, this state is determined to be a follow-up operation, and when 2 seconds have passed since the accelerator pedal was depressed, the low speed stage selection control is canceled and upshifting is possible, and unnecessary driving force is generated. Smooth follow-up driving can be performed.

  Further, in the follow-up control 2 by the vehicle travel control device, as shown in FIG. 4B, when the accelerator pedal is depressed (ON state) during the low speed stage selection control, the return timer starts (time = 0). The return timer time (control time) is obtained based on the deviation DP between the current accelerator opening P and the steady travel accelerator opening P0. In this case, since the depression amount of the accelerator pedal is not large, the deviation of the accelerator opening is small, and the return timer time is set to 2 seconds. Since the accelerator opening does not change, the return timer time remains 2 seconds. Therefore, this state is determined to be a follow-up operation, and when 2 seconds have passed since the accelerator pedal was depressed, the low speed stage selection control is canceled and upshifting is possible, and unnecessary driving force is generated. Smooth follow-up driving can be performed.

  Then, in the overtaking control by the vehicle travel control device, as shown in FIG. 4-3, when the accelerator pedal is depressed (ON state) during the low speed stage selection control, the return timer starts (time = 0). The return timer time (control time) is obtained based on the deviation DP between the current accelerator opening P and the steady travel accelerator opening P0. In this case, since the depression amount of the accelerator pedal is large, the deviation of the accelerator opening is large, and the return timer time is set to 6 seconds. The return timer time is maintained at 6 seconds with no change in the accelerator opening, but the return time from 6 seconds because the accelerator pedal was returned before the return timer count time exceeded 6 seconds. Updated to 4 seconds. Therefore, this state is determined to be an overtaking operation, and when the accelerator pedal is returned, the return timer time is updated to 4 seconds, but at this point, more than 4 seconds have passed since the accelerator pedal was already depressed. The low-speed stage selection control is canceled and the upshift is possible. Therefore, the selection control of the low speed stage has continued for 4 seconds or more, and the driving force necessary for overtaking can be secured for a predetermined time to perform a smooth overtaking operation.

  As described above, in the vehicle travel control apparatus according to the first embodiment, the inter-vehicle distance between the own vehicle and the preceding vehicle is detected, and the inter-vehicle distance is equal to or less than the set value, or the inter-vehicle distance between the own vehicle and the preceding vehicle. When the inter-vehicle time obtained by dividing the distance by the vehicle speed becomes equal to or less than the predetermined value, the automatic transmission 13 of the vehicle is shifted down and a downshift is performed to decelerate the vehicle by the action of the engine brake. While maintaining the low speed stage, during this low speed stage selection control, the deviation between the current accelerator opening and the accelerator opening required for steady running of the vehicle is calculated, and this control is based on the deviation of the accelerator opening. The control time until the end of the operation is set, and when this control time elapses, the selection control of the low speed stage is canceled.

  Therefore, by using the deviation between the current accelerator opening and the accelerator opening required for steady driving of the host vehicle, it is possible to properly read the driving intended by the driver. The selection control is canceled and upshifting is possible, and smooth follow-up traveling can be performed without generating unnecessary driving force. On the other hand, in overtaking operation, the selection control of the low speed stage is continued for a predetermined time. Therefore, the driving force necessary for overtaking can be secured and smooth overtaking operation can be performed. As a result, the drivability can be improved by ensuring the traveling performance according to the driver's intention.

  During low speed selection control, the deviation between the current accelerator opening and the accelerator opening required for steady driving is constantly monitored in real time. When this deviation changes, the control time is updated as needed. As a result, the driver's intention to drive can be read immediately to enable appropriate shift control, and drivability can be improved. Furthermore, even if the return timer for measuring the control time is started by executing the selection control of the low speed stage, if the accelerator pedal is returned and turned OFF, the return timer is reset so that the driver's driving intention It is possible to read the change with certainty to enable proper shift control.

  FIG. 6 is a flowchart of control by the vehicle travel control apparatus according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  The schematic configuration of the vehicle travel control apparatus of the present embodiment is substantially the same as that of the first embodiment described above, and a description thereof will be omitted. In the vehicle travel control device of the present embodiment, when the condition for canceling the low speed stage selection control is established after the downshift is performed, the time until the inter-vehicle distance between the host vehicle and the preceding vehicle becomes approximately zero is calculated. When the time until the inter-vehicle distance becomes substantially zero is longer than a predetermined time set in advance, release of the low speed stage selection control is permitted and the control is terminated. Hereinafter, the traveling control of this embodiment will be described.

  In the vehicle travel control apparatus of the present embodiment, as shown in FIG. 6, in step S101, the ECU 15 determines whether or not an execution condition for executing a downshift is satisfied. That is, it is determined that the downshift execution condition is satisfied when the accelerator pedal is in the OFF state and the inter-vehicle time is smaller than a predetermined value set in advance. If the downshift execution condition is satisfied in step S101, the process proceeds to step S102 to start the downshift, and the ECU 15 shifts down the shift stage of the automatic transmission 13 from, for example, the fourth speed to the third speed. Thus, the hydraulic control device 14 is controlled.

  In step S103, when the downshift is executed and the shift stage after the shift is maintained, the driver's intention to accelerate is confirmed by determining the ON state of the accelerator pedal. If the accelerator pedal ON state is not determined in step S103, the low speed stage selection control is continued. On the other hand, if the accelerator pedal ON state is determined, the process proceeds to step S104, and the low speed stage selection control is performed. It is determined whether a condition for termination is satisfied. If it is determined in step S104 that the low-speed stage selection control end condition is not satisfied, the process returns to step S103, and if it is determined that the low-speed stage selection control end condition is satisfied, The process proceeds to S105.

  The determination of whether the low-speed stage selection control termination condition is satisfied may use the processing in the first embodiment (steps S11 to S18). That is, the deviation DP between the current accelerator opening P and the accelerator opening P0 necessary for steady running is calculated, the control time is set based on the deviation DP of the accelerator opening, and this control time is set using the return timer. It is determined that the end condition for the selection control for the low speed stage is satisfied. In addition to this method, the determination of whether the low-speed stage selection control end condition is satisfied may be, for example, when the current accelerator opening exceeds a predetermined value, or when the accelerator opening time exceeds a predetermined value. It may be determined that is established.

  If it is determined in step S104 that the low-speed stage selection control end condition is satisfied, in step S105, the time from this point until the distance between the host vehicle and the preceding vehicle becomes substantially zero, that is, the collision. It is determined whether the time is shorter than a predetermined value. As described in the first embodiment, the collision time is a time obtained by dividing the current inter-vehicle distance between the own vehicle and the preceding vehicle by the relative speed between the own vehicle and the preceding vehicle. In this case, instead of the collision time, an inter-vehicle time obtained by dividing the inter-vehicle distance between the current own vehicle and the preceding vehicle by the own vehicle speed may be used.

  When it is determined in step S105 that the collision time is shorter than the predetermined value, it is determined that the distance between the host vehicle and the preceding vehicle is not sufficient. When the low speed stage selection control is terminated in this state, May collide with the front car. Therefore, the ECU 15 enters a standby state without releasing the low speed stage selection control. On the other hand, when it is determined that the collision time is longer than the predetermined value, it is determined that the distance between the host vehicle and the preceding vehicle is sufficient. There is almost no risk of crashing into the front car. Therefore, the process proceeds to step S106, and the ECU 15 ends the low speed stage selection control and executes the normal gear position control. That is, the ECU 15 controls the automatic transmission 13 by the hydraulic control device 14 based on the throttle opening, the vehicle speed, and the like.

  As described above, in the vehicle travel control apparatus according to the second embodiment, when the end condition of the low speed stage selection control is satisfied, the collision time until the inter-vehicle distance between the own vehicle and the preceding vehicle becomes substantially zero is set. Calculation is made, and when the collision time is longer than a predetermined value set in advance, the release of the selection control for the low speed stage is permitted, and this control is terminated.

  Therefore, when canceling the selection control of the low speed stage, considering the time until the inter-vehicle distance between the host vehicle and the preceding vehicle becomes substantially zero, the shift operation is repeatedly performed so that the inter-vehicle distance changes frequently. Control is not performed, and control that does not impair safety due to extremely short distances between vehicles is ensured, ensuring driving performance according to the driver's intention and improving drivability Can be achieved.

  In the second embodiment described above, when it is determined in step S105 that the collision time is shorter than the predetermined value, the collision time may be longer than the predetermined value without releasing the low speed stage selection control. At this time, the delay time may be calculated according to the difference between the collision time and the predetermined value or the ratio between the two, and the end time of the low speed stage selection control may be set. In addition, a second predetermined value smaller than the predetermined value used when permitting the low speed stage selection control end condition is set, and when it is determined that the collision time is shorter than the second predetermined value, the shift speed is further lowered. The downshift may be executed. Further, instead of the collision time, an inter-vehicle distance or an inter-vehicle time taking into account the relative speed may be used.

  FIG. 7 is a schematic configuration diagram illustrating a vehicle travel control apparatus according to a third embodiment of the present invention, and FIG. 8 is a flowchart of control by the vehicle travel control apparatus according to the third embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the above-described first embodiment, when the inter-vehicle time between the host vehicle and the preceding preceding vehicle becomes a predetermined value or less, the automatic transmission 13 of the host vehicle executes a downshift to maintain the low speed stage after the shift. When the accelerator pedal is operated during this control, the control time until this control is completed is set based on the deviation between the current accelerator opening and the accelerator opening required for steady travel. After the time elapses, the selection control of the low speed stage is canceled.

  In this case, it is desirable that the control time from when the accelerator pedal is operated to when the selection control at the low speed stage is canceled ensures traveling performance according to the driver's intention. However, this control time varies depending on the surrounding road conditions on which the vehicle travels. In other words, the set control time is appropriate for the driver when traveling on a road where the vehicle is vacant, but when the vehicle is traveling on a crowded road, That is, it is felt that it is too early to cancel the selection control of the low speed stage. This is probably because the driver's driving operation (output control) is cautious when driving on a busy road, and he dislikes upshifts at an early timing.

  Therefore, in the third embodiment, when the accelerator pedal is operated during the execution of the control for selecting the shift stage on the low speed stage side by utilizing the navigation system as the congestion degree detecting means for detecting the congestion degree of the surrounding road, Set the control time until this control is completed based on the deviation between the current accelerator opening and the accelerator opening required for steady driving, and change this control time based on the degree of congestion detected by the navigation system (control Time setting means). In this case, the control time is set longer as the degree of congestion is larger. When this control time has elapsed, the selection control of the low speed stage is canceled.

  Therefore, as shown in FIG. 7, the navigation system 41 for obtaining road information is connected to the ECU 41. Although not shown, the navigation system 41 is connected with an operation unit, a display unit, and a speaker. The crew can input various instruction data using this operation unit, and can display map data around the current location, information such as the current location, destination location, route, etc. on the display unit, and use a speaker. You can listen to the guidance voice.

  The navigation system 41 has a GPS receiver, a gyroscope, and the like, and detects the absolute position (latitude and longitude) of the vehicle. On the other hand, various map data are stored in a recording medium such as a CD-ROM or DVD. The necessary map data can be searched and displayed on the display unit. Furthermore, the navigation system 41 has a road information communication system (VICS: Vehicle Information Communication System), and can obtain information on surrounding road conditions, that is, congestion level.

  In this case, for example, the navigation system 41 acquires traffic information around the vehicle from the traffic information center using the road traffic information communication system, and exists in a specific road section around the current location where the vehicle travels based on the acquired traffic information. The number of vehicles to be used is estimated, and the congestion degree is calculated based on the number of vehicles existing in the road section.

  Therefore, in this embodiment, when the accelerator pedal is operated during the execution of the control for selecting the shift stage on the low speed stage side, the control is performed based on the deviation between the current accelerator opening and the accelerator opening necessary for steady running. While the time is set, the navigation system 41 detects the congestion degree of the surrounding road on which the vehicle is traveling by the road traffic information communication system, and determines that the detected congestion degree is higher than a preset determination value. Change the control time to be longer.

  Here, the traveling control by the vehicle traveling control apparatus of the present embodiment will be described based on the flowchart of FIG.

  In the travel control of the vehicle, as shown in FIG. 8, it is determined in step S201 whether the vehicle is traveling ahead. If there is a vehicle ahead, the vehicle is detected by the laser radar sensor 34 in step S202. Measure the distance between the car and the front car. In step S203, it is determined whether the inter-vehicle time calculated based on the measured inter-vehicle distance is smaller than a predetermined determination value. If the inter-vehicle time is smaller than the preset determination value in step S203, it is determined in step S204 whether or not the accelerator pedal is in an OFF state. Here, if the accelerator pedal is in the OFF state, the process shifts to step S205 to execute the downshift control.

  That is, it is determined that the downshift execution condition is satisfied when the inter-vehicle time is smaller than a predetermined determination value and the accelerator pedal is in the OFF state, and the downshift is executed in step S205. That is, the ECU 15 waits for the downshift execution condition to be satisfied, determines to shift down the shift speed of the automatic transmission 13 from, for example, the fourth speed to the third speed, and establishes the determined shift speed. The hydraulic control device 14 is controlled. In other words, downshift control is executed, and control (low speed stage selection control) is performed in which the low speed stage (third speed) after shifting is maintained.

  In step S206, after the downshift is executed, the accelerator pedal is turned on. If the accelerator pedal ON state is not determined in step S206, the low speed stage selection control is continued. If the accelerator pedal ON state is determined, the process proceeds to step S207, where the return timer is set. Start it. In step S208, the accelerator opening P0 necessary for steady running of the host vehicle is calculated at the current vehicle speed and shift speed. In step S209, the current accelerator opening P and the accelerator necessary for steady running are calculated. A deviation DP with respect to the opening P0 is calculated, and in step S210, a control time from the receipt of the low speed stage selection control release command based on the accelerator opening deviation DP to the end of this control, that is, The return timer time is calculated according to Table 1.

  In step S211, the navigation system 41 detects the congestion degree of the surrounding road, and in step S212, it is determined whether the detected congestion degree of the surrounding road is higher than a preset determination value. If it is determined in step S212 that the degree of congestion of the surrounding road is higher than the determination value, the process proceeds to step S214, and the set return timer time is set to a longer (control time) while the congestion of the surrounding road is set. If it is determined that the degree is equal to or less than the determination value, the process proceeds to step S213 without being changed. That is, when the surrounding road on which the vehicle is traveling is congested, the return timer time is set longer.

  In step S213, it is determined whether or not the return timer time (control time) set for the return timer has been exceeded, that is, whether or not the return timer time has elapsed. Here, if the return timer time has not yet elapsed, it is checked in step S215 whether or not the accelerator pedal has been turned off. If the accelerator pedal has already been returned and the accelerator pedal is in the OFF state, the return is made in step S216. After resetting the timer, the process returns to step S206 and waits for the accelerator pedal to be turned on again.

  On the other hand, if it is determined in step S215 that the accelerator pedal is not in the OFF state, the process returns to step S208, where again the accelerator opening P0 necessary for steady running is calculated, and in step S209, the current accelerator opening P is calculated. A deviation DP from the accelerator opening P0 necessary for steady travel is calculated, and a control time, that is, a return timer time is calculated from Table 1 based on the accelerator opening deviation DP in step S210. At this time, the deviation DP of the accelerator opening increases or decreases due to a change in the accelerator pedal depression amount (accelerator opening) by the driver, so that the return timer time is updated. In step S211, the degree of congestion on the surrounding road is detected. In step S212, it is determined whether the degree of congestion on the surrounding road is higher than the determination value. If it is determined that the degree of congestion is higher than the determination value, step S214 Change the reset timer time set in.

  In step S213, it is determined again whether the count time of the return timer exceeds the return timer time, that is, whether the return timer time has elapsed. If the return timer time has not yet elapsed, the process proceeds to step S215, and the same processing as described above is performed. On the other hand, if the return timer time has elapsed in step S213, the process proceeds to step S217, the low speed stage selection control is canceled to enable upshifting, and normal gear stage control is executed. That is, the ECU 15 controls the automatic transmission 13 by the hydraulic control device 14 based on the throttle opening, the vehicle speed, and the like.

  Thus, in the vehicle travel control apparatus of the third embodiment, when the accelerator pedal is operated during the execution of the control to execute the downshift of the automatic transmission 13 and maintain the low speed stage after the shift, Based on the deviation between the current accelerator opening and the accelerator opening required for steady driving, a control time until this control is completed is set, and the degree of congestion of the surrounding road on which the vehicle is traveling by the navigation system 41 The control time set according to the degree of congestion is changed, and when the control time elapses, the low speed stage selection control is canceled.

  Therefore, by using the degree of congestion on the surrounding roads, it is possible to appropriately read the driving intended by the driver, and for driving such as during heavy traffic congestion, the control time is lengthened and the shift is increased at an early timing. Can be prevented and smooth driving according to road conditions can be performed. As a result, drivability can be improved by ensuring the driving performance adapted to the driver's feeling.

  In Example 3 described above, the navigation system 41 acquires traffic information around the vehicle by the road traffic information communication system, estimates the number of vehicles existing in a specific road section based on the acquired traffic information, Although the degree of congestion is calculated based on the number of vehicles, the present invention is not limited to this method. For example, when the degree of congestion is high, paying attention to the fact that the average vehicle speed is low (less than 40 km / h), the degree of congestion may be calculated based on the average vehicle speed of the own vehicle or surrounding vehicles. In addition, the degree of congestion may be detected based on the ratio of the vehicle detection time of the preceding vehicle to the time when it is not detected, or the frequency of acceleration / deceleration control within a predetermined time. A statistical congestion degree for each hour may be stored in advance, and the congestion degree may be detected based on the stored information. Also, based on image information around the vehicle or information from the radar, the number of vehicles existing in a predetermined range is compared with a predetermined value, and it is determined that the vehicle is congested when the predetermined value is exceeded. You may do it.

  Further, in each of the above-described embodiments, as an instruction signal for increasing the driving force, an idle OFF signal (steps S13, S204, S206) from the throttle position sensor 27 with an idle switch or an accelerator opening degree from the accelerator position sensor 21 ( Steps S16 and S209) are used, but are not limited to these. For example, an ON signal of an accelerator pedal switch or an increase in throttle opening may be used.

  Further, in each embodiment, the ECU 15 as the control time setting means waits until the low speed stage selection control is canceled based on the deviation between the current accelerator opening and the accelerator opening in the steady operation. However, the throttle opening described above may be used instead of the accelerator opening. Further, although the ECU 15 sets the control time from the deviation of the accelerator opening, it may be controlled by replacing this control time with the distance, and in this case, the process is terminated after the determination of canceling the low speed stage selection control is made. The low speed stage selection control may be terminated when the travel distance until the vehicle reaches the control distance.

  Furthermore, when setting the control time from the deviation of the accelerator opening, it may be calculated by taking into account the vehicle weight (loading capacity, number of passengers, etc.) and road gradient (uphill, downhill). The calculation accuracy is improved, and control according to the driver's intention becomes possible.

  As described above, the vehicle travel control apparatus according to the present invention sets the end timing of the low speed stage selection control according to the deviation between the current accelerator opening and the accelerator opening for steady travel, The present invention is useful for a vehicle travel control device that performs inter-vehicle distance control, such as a transmission, a continuously variable transmission, a manual transmission with an automatic transmission mode, and a hybrid vehicle drive device.

1 is a schematic configuration diagram illustrating a vehicle travel control apparatus according to a first embodiment of the present invention. 3 is a flowchart of control by the vehicle travel control apparatus according to the first embodiment. 2 is a time chart of control by the vehicle travel control device of Embodiment 1; 3 is a time chart of the follow-up control 1 by the vehicle travel control device of the first embodiment. 6 is a time chart of follow-up control 2 by the vehicle travel control apparatus of the first embodiment. 3 is a time chart of overtaking control by the vehicle travel control device of Embodiment 1; It is a graph showing the accelerator opening at the time of follow-up driving | running | working. It is a graph showing the accelerator opening degree at the time of overtaking driving. It is a flowchart of control by the traveling control apparatus of the vehicle which concerns on Example 2 of this invention. It is a schematic block diagram showing the traveling control apparatus of the vehicle which concerns on Example 3 of this invention. 10 is a flowchart of control by a vehicle travel control apparatus according to a third embodiment.

Explanation of symbols

11 Engine 13 Automatic transmission 14 Hydraulic control device 15 Electronic control unit, ECU (driving force detection means, control time setting means)
21 Accelerator position sensor 27 Throttle position sensor 30 Vehicle speed sensor 34 Laser radar sensor 41 Navigation system (congestion degree detection means)

Claims (8)

  Based on the positional relationship between the host vehicle and the front vehicle, the shift speed of the transmission is selectively changed to the low speed side based on the positional relationship with the front vehicle, and an instruction to increase the driving force of the host vehicle In the vehicle travel control device that terminates the control to detect and change the selection to the low speed stage side, the driving force detecting means for detecting the driving force required for steady traveling of the host vehicle, and the driving force increase instruction Control time setting means for setting a control time until the control for selectively changing to the low speed stage side is completed based on the deviation between the value to be detected and the driving force necessary for steady running detected by the driving force detecting means. A travel control device for a vehicle.   2. The vehicle travel control apparatus according to claim 1, wherein the control time is set longer as a deviation between a value corresponding to the driving force increase instruction and a driving force required for steady traveling detected by the driving force detection means is larger. A travel control device for a vehicle, characterized by comprising:   3. The vehicle travel control device according to claim 1, wherein the control time setting means is changed when a value corresponding to the driving force increase instruction is changed during the control to selectively change to the low speed stage side. A travel control device for a vehicle, wherein the control time is updated based on a value corresponding to a driving force increase instruction.   3. The vehicle travel control apparatus according to claim 1, wherein the control time is canceled when the driving force increase instruction is canceled during the control to selectively change to the low speed stage side. Travel control device.   5. The vehicle travel control device according to claim 1, wherein the control time setting means is a current accelerator opening as a value corresponding to the driving force increase instruction, and is necessary for steady travel. A travel control device for a vehicle, wherein a control time until the control for selectively changing to the low speed stage is completed based on a deviation from a steady accelerator opening determined from a driving force is set.   Based on the positional relationship between the host vehicle and the front vehicle, the shift speed of the transmission is selectively changed to the low speed side based on the positional relationship with the front vehicle, and an instruction to increase the driving force of the host vehicle In the vehicle travel control device that terminates the control to change the selection to the low speed side by detecting the vehicle, the vehicle control device when the return to the normal gear position on the high speed side is determined after the selection change to the low speed side is made. Time calculating means for calculating the time until the distance between the vehicle and the preceding vehicle becomes substantially zero, and the time until the distance calculated by the time calculating means becomes substantially zero is longer than a predetermined time set in advance. A vehicle travel control device comprising control end permission means for permitting the end of the control sometimes.   Based on the positional relationship between the host vehicle and the front vehicle, the shift speed of the transmission is selectively changed to the low speed side based on the positional relationship with the front vehicle, and an instruction to increase the driving force of the host vehicle In the vehicle travel control apparatus that terminates the control to change the selection to the low-speed stage side, the congestion degree detection means for detecting the congestion degree of the surrounding road, and the congestion degree detected by the congestion degree detection means And a control time setting means for setting a control time until the control for selectively changing to the low speed stage is completed. 8. The vehicle travel control device according to claim 7, wherein the control time is set longer as the congestion level detected by the congestion level detection means is larger.

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