JP2012101636A - Traveling control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise fuel consumption performance related to a traveling control device for vehicle which can raise fuel consumption performance at traveling time.SOLUTION: The traveling control device for vehicle which controls a traveling state of the vehicle equipped with an engine 10 as a power source, and a power transmission device which transmits power of the engine 10 to driving wheels WL and WR, obtains gradients of a travel way between the own vehicle and a predetermined distance ahead, performs inertia traveling decreased in fuel supply quantity or stopping the fuel supply to the engine 10 while being in a state where power transmission can be made between the engine 10 and the driving wheels WL and WR, when the own vehicle may continue acceleration also at a predetermined distance point ahead, and controls a power clutch part (at least one of a lock-up clutch 35 and an input clutches C1) of a power transmission device so that power transmission between the engine 10 and the driving wheels WL and WR may be disconnected, and performs the inertia travel, when the own vehicle may start to slow down before exceeding the predetermined distance ahead.

Description

  The present invention relates to a vehicular travel control device that can improve fuel efficiency during travel.

  2. Description of the Related Art Conventionally, as a technique for improving fuel economy performance during traveling, a technique of stopping fuel supply to an engine (fuel cut) and traveling with inertia is known. For example, this type of technology is disclosed in Patent Documents 1 and 2 below. In the technology of Patent Document 1, if the driver requests acceleration when performing coasting on a downhill road, the fuel cut is performed by upshifting the transmission to the high speed side. It gives the driver a sense of acceleration. Japanese Patent Application Laid-Open No. H10-228561 discloses a technique for slowing down the engine speed by slip-controlling a lock-up clutch when fuel cut is executed during deceleration. In this technology, when the engine speed decreases to a threshold value higher than the fuel cut release threshold value during the slip control, downshift is permitted if the slope of the downhill road is a predetermined value or more. Yes.

Japanese Patent Laying-Open No. 2005-075179 JP 2008-169930 A

  By the way, in the technique of the patent document 1 and 2, the fuel consumption performance is improved rather than the inertia driving | running | working accompanying execution of fuel cut. However, during the inertia running, power transmission between the engine and the drive wheels is possible, and so-called engine braking is working. For this reason, during inertial running, a part of the kinetic energy is discarded as heat by the engine brake. Therefore, in such a vehicle, there is room for improvement in fuel efficiency performance during inertial traveling.

  Accordingly, an object of the present invention is to provide a vehicular travel control device that can improve the disadvantages of the conventional example and improve the fuel efficiency.

  In order to achieve the above object, the present invention provides a vehicular travel control apparatus for controlling a travel state of a vehicle including an engine as a power source and a power transmission device that transmits the power of the engine to drive wheels. Grasping the gradient of the road to the predetermined distance ahead, and when the vehicle may continue to accelerate even at the predetermined distance ahead, the power transmission between the engine and the drive wheels is possible. When the coasting is carried out with the fuel supplied to the engine decreased or the fuel supplied is stopped, the vehicle may start to decelerate before the predetermined distance is exceeded. The inertial running is performed by controlling a power connection / disconnection portion of the power transmission device so that power transmission to and from the driving wheel is cut off.

  Here, when the vehicle is traveling on a downhill road, it is determined whether to select inertial driving in a state where the power transmission is possible or inertial driving in a state where the power transmission is impossible Is desirable.

  Further, the state in which the power transmission is impossible during the traveling by the acceleration / deceleration traveling pattern in which the acceleration traveling from the setting lower limit vehicle speed to the setting upper limit vehicle speed and the deceleration traveling from the setting upper limit vehicle speed to the setting lower limit vehicle speed are alternately repeated. It is desirable that the traveling distance until the host vehicle reaches the set upper limit vehicle speed as the inertia traveling is performed at the predetermined distance.

  The vehicle travel control device according to the present invention improves the fuel efficiency by inertial running with the engine brake generated when there is a possibility that the vehicle continues to accelerate even at a predetermined distance, while the predetermined distance ahead. When there is a possibility that the vehicle will start to decelerate before exceeding, fuel efficiency can be further improved by performing inertial running without generating engine braking.

FIG. 1 is a diagram showing a vehicular travel control apparatus and its applicable vehicle according to the present invention. FIG. 2 is a diagram illustrating an example of a map of an executable area and an execution prohibited area of an acceleration / deceleration running pattern. FIG. 3 is a flowchart for explaining the operation of the vehicular travel control apparatus according to the present invention.

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

  An embodiment of a vehicle travel control apparatus according to the present invention will be described with reference to FIGS.

  Reference numeral 1 in FIG. 1 indicates a vehicle travel control apparatus in the present embodiment. First, an example of a vehicle to be controlled by the vehicle travel control device 1 will be briefly described.

  The vehicle illustrated here includes an engine 10 as a power source, and a transmission 20 that is a part of a power transmission device that transmits the power of the engine 10 to drive wheels WL and WR.

  The engine 10 is an internal combustion engine, an external combustion engine, or the like that converts thermal energy generated by combustion of fuel into mechanical energy (power). The operation of the engine 10 is controlled by an engine electronic control unit (hereinafter referred to as “engine ECU”) 101. Here, the vehicle is provided with a so-called eco-run function for reducing fuel consumption during traveling. For this reason, the engine 10 can be stopped or restarted during traveling. At the time of the stop, the engine ECU 101 can reduce the amount of fuel supplied to the engine 10 to an idle state, for example, or can stop the supply of fuel to the engine 10.

  On the other hand, the transmission 20 is a so-called automatic transmission, and is exemplified as a multi-stage automatic transmission having a plurality of shift speeds (6 forward speeds and 1 reverse speed) having different speed ratios. The transmission 20 includes a torque converter 30 that transmits the output torque of the engine 10 to gears on the gear stage side, and a transmission main body 40 that includes gear groups that form the respective gear stages. The operation of the transmission 20 is controlled by an electronic control unit (hereinafter referred to as “transmission ECU”) 102 for transmission.

  The torque converter 30 includes a pump impeller 31, a turbine runner 32, and a stator 33 housed in a housing (not shown). An input shaft 21 of the transmission 20 is connected to the pump impeller 31 so as to rotate integrally. A first torque transmission shaft 51 connected to first to fourth clutches C1 to C4, which will be described later, is connected to the turbine runner 32 so as to rotate together. The stator 33 is connected to the housing of the torque converter 30 via a one-way clutch 34. The output shaft 11 of the engine 10 is connected to the input shaft 21 of the transmission 20.

  The torque converter 30 is provided with a lockup clutch 35 that rotates the pump impeller 31 and the turbine runner 32 together. The lock-up clutch 35 includes a first engagement portion 35a coupled to rotate integrally with the input shaft 21, and a second engagement coupled to rotate integrally with the first torque transmission shaft 51. Part 35b. At least one of the first engaging portion 35a and the second engaging portion 35b is provided with a friction material at a contact portion when these are pressed.

  The lock-up clutch 35 allows torque transmission between the first engagement portion 35a and the second engagement portion 35b by crimping or separating the first engagement portion 35a and the second engagement portion 35b. A disengageable disengagement state, a slip engagement state in which the first engagement portion 35a and the second engagement portion 35b are engaged in a slip state (half-engagement state), and a complete engagement state in which these are rotated together. To produce. Various states of the lock-up clutch 35 can be created by a hydraulic control or an electric actuator 36 that operates according to a control command of the transmission ECU 102. When the lock-up clutch 35 is controlled to be in a fully engaged state or a semi-engaged state, power transmission between the engine 10 and the drive wheels WL and WR is possible unless the transmission main body 40 is in the neutral state. Become. On the other hand, when the lockup clutch 35 is controlled to be in the released state, power transmission between the engine 10 and the drive wheels WL and WR is cut off regardless of the state of the transmission main body 40. That is, the lockup clutch 35 functions as a power connection / disconnection part of a power transmission device that disables or enables power transmission between the engine 10 and the drive wheels WL and WR.

  The transmission main body 40 includes first to fourth clutches C1 to C4, first to third planetary gear devices 41 to 43 made of a sun gear, etc., these first to fourth clutches C1 to C4, and the first To third planetary gear devices 41 to 43, second to fourth torque transmission shafts 52 to 54 capable of transmitting torque, and first to fourth brakes B1 to B4. In the transmission main body 40, the transmission ECU 102 engages or disengages a predetermined clutch and a brake among the first to fourth clutches C1 to C4 and the first to fourth brakes B1 to B4. To the next gear position.

  Here, the first clutch C1 is called an input clutch, a forward clutch, a forward clutch, or the like. Hereinafter, this first clutch is referred to as an “input clutch”. The input clutch C1 includes a first engagement portion C1a connected to rotate integrally with the first torque transmission shaft 51, and a second engagement portion connected to the third torque transmission shaft 53 via the one-way clutch F0. Engaging portion C1b. At least one of the first engagement portion C1a and the second engagement portion C1b is provided with a friction material at a contact portion when these are pressed. The one-way clutch F0 is for preventing the sun gear of the second planetary gear unit 42 and the third torque transmission shaft 53 from rotating in the reverse direction (rotation in the direction opposite to the rotation of the first torque transmission shaft 51). . The third torque transmission shaft 53 is connected to the output shaft 22 of the transmission 20 via the sun gear and pinion gear of the third planetary gear device 43. The output shaft 22 is connected to a power transmission unit 60 such as a differential device, and is connected to the drive wheels WL and WR via the power transmission unit 60.

  Like the lockup clutch 35, the input clutch C1 is in a disengaged state in which torque transmission between the first engagement portion C1a and the second engagement portion C1b is impossible, and the first engagement portion C1a and the second engagement portion C1b. It is possible to create a semi-engagement state in which the portion C1b is engaged in a slip state, and a complete engagement state in which these are integrally rotated. Various states of the input clutch C1 can be created by a hydraulic control or an electric actuator 49 that operates according to a control command of the transmission ECU 102. When the input clutch C1 is controlled to be in a fully engaged state or a semi-engaged state, power transmission between the engine 10 and the drive wheels WL and WR becomes possible unless the lockup clutch 35 is in a released state. . On the other hand, when the input clutch C1 is controlled to be in the disengaged state, a neutral state in which power transmission between the engine 10 and the drive wheels WL and WR is interrupted regardless of the state of the lock-up clutch 35. That is, the input clutch C1 also functions as a power connection / disconnection part of a power transmission device that disables or enables power transmission between the engine 10 and the drive wheels WL and WR, similarly to the lock-up clutch 35.

  As described above, this vehicle has an eco-run function. The eco-run function exemplified here is based on an acceleration / deceleration traveling pattern in which acceleration traveling and deceleration traveling are alternately repeated between a set lower limit vehicle speed and a set upper limit vehicle speed. In the eco-run of this acceleration / deceleration running pattern, basically, acceleration running from the set lower limit vehicle speed to the set upper limit vehicle speed and deceleration running from the set upper limit vehicle speed to the set lower limit vehicle speed are alternately repeated. The vehicle travel control device 1 uses the power of the engine 10 to accelerate the host vehicle to the set upper limit vehicle speed when the host vehicle decelerates to the set lower limit vehicle speed. If the fuel supply to the engine 10 is stopped at that time (that is, in the fuel cut state), the vehicle travel control device 1 causes the engine ECU 101 to restart the engine 10. On the other hand, the vehicle travel control device 1 reduces the amount of fuel supplied to the engine 10 to, for example, an idle state or stops the supply of fuel to the engine 10 when the host vehicle accelerates to the set upper limit vehicle speed. Then, the host vehicle is decelerated to the set lower limit vehicle speed by inertial running. In the vehicle, by performing the eco-run of the acceleration / deceleration traveling pattern, the fuel consumption of the engine 10 is suppressed during inertial traveling, so that the fuel efficiency is improved. In order to improve the fuel efficiency performance by this eco-run, it is desirable to stop the fuel supply to the engine 10 rather than keeping the engine 10 in an idle state.

  When the eco-run of this acceleration / deceleration driving pattern is executed on a steep uphill road, the deceleration due to gravitational acceleration is large, so the fuel consumption during acceleration driving increases, the driving distance during deceleration driving decreases, and the fuel efficiency It is difficult to improve performance. Further, when executed on a steep downhill road, acceleration due to gravitational acceleration is large, and therefore, there is a possibility that traveling in an acceleration / deceleration traveling pattern cannot be realized without performing deceleration traveling. For this reason, it is preferable not to execute the eco-run of this acceleration / deceleration running pattern on a steep uphill road or downhill road. For example, in this example, in order to determine whether or not an acceleration / deceleration traveling pattern can be executed, a map (FIG. 2) corresponding to the current vehicle speed and the gradient of the traveling path is prepared. In the map, areas that are not suitable for execution of such acceleration / deceleration running patterns are set on the uphill road side and the downhill road side as areas where execution of acceleration / deceleration running patterns is prohibited. Since the information on this map changes according to the vehicle weight, the front projected area of the vehicle, the grip performance of the wheels, etc., it is preset for each vehicle type. In this map, an area between the two acceleration / deceleration travel pattern execution prohibition areas is set as an execution area of the acceleration / deceleration travel pattern.

  Here, during inertial traveling of the acceleration / deceleration traveling pattern, power transmission between the engine 10 and the drive wheels WL and WR is possible, so a so-called engine brake is applied to the own vehicle, and a part of the kinetic energy is consumed. It is thrown away as heat. For this reason, the vehicle can further improve fuel efficiency by performing inertial running without applying the engine brake. Therefore, in order to improve the fuel efficiency in the eco-run of this acceleration / deceleration driving pattern, the fuel supply to the engine 10 is stopped during inertial driving, and the power connecting / disconnecting part (the lock-up clutch 35 and the input) It is desirable to release at least one of the clutches C1 so that the engine brake does not work.

  In the eco-run of the acceleration / deceleration running pattern described so far, if the running road is a flat road or an uphill road (excluding a steep slope), the desired acceleration / deceleration running can be performed regardless of the presence or absence of engine braking. For this reason, when the traveling road is a flat road or an uphill road (excluding a steep slope), it is preferable to coast by inertia without applying the engine brake, and to improve the fuel efficiency by extending the traveling distance during deceleration traveling. it can. Therefore, in this case, the inertia traveling without the engine brake is performed in the deceleration traveling of the acceleration / deceleration traveling pattern, and the acceleration / deceleration traveling pattern for performing the inertia traveling without the engine brake in FIG. 2 (hereinafter referred to as “first acceleration / deceleration traveling”). The executable area of “pattern” is selected. In the feasible region of the first acceleration / deceleration traveling pattern, acceleration traveling and deceleration traveling by inertia traveling without engine braking are performed. The slope of the uphill road is a size that does not give the driver an excessive feeling of deceleration during coasting, and includes a gentle slope. In this case, the fuel consumption performance can be further improved by stopping the supply of fuel to the engine 10 during coasting. The boundary between the accelerating / decelerating travel pattern execution prohibition region on the uphill road side in the feasible region of the first acceleration / deceleration traveling pattern is, for example, as shown in FIG. It is set to a place where the vehicle can be decelerated due to deceleration that does not give the driver a sense of incongruity (excessive deceleration). For example, when the traveling road is an uphill road, the deceleration acting on the own vehicle (strictly the absolute value thereof) with respect to the acceleration acting on the own vehicle (strictly the absolute value thereof) does not include the engine brake. ) Is large enough to give an excessive feeling of deceleration, the eco-run of the acceleration / deceleration running pattern (including not only the first acceleration / deceleration running pattern but also the following second acceleration / deceleration running pattern) is prohibited.

  When the road is downhill, the vehicle accelerates even if it is not steep, due to the influence of the gradient, vehicle weight (including the weight of passengers and loads), and gravitational acceleration. There is a fear. Here, the acceleration acting on the host vehicle is determined by the gradient of the downhill road, the vehicle weight, and the gravitational acceleration. The deceleration acting on the host vehicle is determined by engine brake, air resistance and rolling resistance. For this reason, on the downhill road, the deceleration increases by applying the engine brake, so that the acceleration of the own vehicle can be reduced. In the map of FIG. 2, an executable region of an acceleration / deceleration traveling pattern (hereinafter referred to as “second acceleration / deceleration traveling pattern”) for performing inertial traveling with an engine brake on a downhill road (excluding a steep slope) is set. . In the feasible region of the second acceleration / deceleration running pattern, acceleration running and deceleration running by inertia running with engine brake are performed. The boundary with the execution prohibition area of the acceleration / deceleration running pattern on the downhill road side in the executable area of the second acceleration / deceleration running pattern is set, for example, at a place where constant speed running is achieved by the inertia running. In other words, when the traveling road is a downhill road, the acceleration (strictly speaking, its absolute value) acting on the own vehicle is more than the deceleration acting on the own vehicle (strictly, it is the absolute value and includes the engine brake). If it is larger, the eco-run of the acceleration / deceleration running pattern (including not only the second acceleration / deceleration running pattern but also the first acceleration / deceleration running pattern) is prohibited. Also in this case, the fuel efficiency can be further improved by stopping the supply of fuel to the engine 10 during inertial running.

  Here, in this exemplary vehicle, there is a combination of a vehicle speed and a gradient on a downhill road (excluding a steep slope), which becomes a constant speed travel when coasting with no engine brake applied. In the map of FIG. 2, the constant speed traveling portion is a boundary, and the area below this (the side on which the slope of the downhill road becomes larger) is set as the executable area of the second acceleration / deceleration traveling pattern, and the area above it (Uphill road side) is set as an executable area of the first acceleration / deceleration running pattern. Therefore, the first acceleration / deceleration traveling pattern performs inertial traveling without engine braking not only on the above-described flat road and uphill road (excluding a steep slope) but also on a downhill road. Also in this case, the fuel efficiency can be further improved by stopping the supply of fuel to the engine 10 during inertial running.

  As described above, in the feasible region of the acceleration / deceleration running pattern, depending on the speed of the host vehicle and the gradient of the running path, the vehicle may be coasted with an engine brake, or may be coasted without an engine brake. Here, as described above, when the engine brake is operated, the fuel efficiency is deteriorated. For this reason, it is desirable that the vehicle during the eco-run of the acceleration / deceleration running pattern is coasted with the engine brake not applied as much as possible. However, in the feasible region of the second acceleration / deceleration running pattern in FIG. 2, if the engine brake is not applied during inertial running, the acceleration exceeds the deceleration and the vehicle continues to accelerate and exceeds the set upper limit vehicle speed. There is a possibility that. On the other hand, even if the vehicle is coasting with no engine brake applied, the vehicle will reach the set maximum vehicle speed, depending on the current road gradient, vehicle weight, etc., and on the road ahead. At this point, the vehicle may start to decelerate before reaching the set upper limit vehicle speed, and the set upper limit vehicle speed may not be exceeded. This is a situation where the acceleration is decreased while the acceleration is decreased due to a change in the gradient of the traveling road, for example, when the traveling road changes from a downhill road to a flat road or an uphill road before the vehicle reaches the set upper limit vehicle speed. It is.

  Therefore, in the vehicle travel control device 1 of the present embodiment, even if the second acceleration / deceleration travel pattern in which inertia traveling is performed with an engine brake is executable, the set upper limit vehicle speed is set by acceleration by inertia traveling without engine braking. If the vehicle starts to decelerate due to the gradient of the travel path up to the predetermined distance before the vehicle exceeds the predetermined distance ahead, coasting without engine brake is executed. As a result, the vehicle starts to decelerate when reaching the set upper limit vehicle speed or before reaching the set upper limit vehicle speed, so that the fuel efficiency performance is improved by inertial running without engine brake without exceeding the set upper limit vehicle speed. Can do.

  Specifically, the vehicular travel control device 1 compares the current vehicle speed and the current gradient of the travel path with the map of FIG. 2 and performs inertial travel without engine brake in the acceleration / deceleration travel pattern or with engine brake. Judge whether to perform inertial driving. Here, it is determined whether it corresponds to the feasible region of the first acceleration / deceleration traveling pattern in FIG. 2 or the feasible region of the second acceleration / deceleration traveling pattern.

  The vehicle traveling control device 1 acquires the vehicle speed from the vehicle speed detection device 71 such as a vehicle speed sensor or a wheel speed sensor. On the other hand, the travel control device 1 for a vehicle acquires the gradient of the travel path from the travel environment information acquisition device 72. The travel environment information acquisition device 72 is configured by, for example, a car navigation system and a GPS (Global Positioning System). This travel environment information acquisition device 72 is based on the vehicle position information by GPS and the map information of the car navigation system (including travel environment information such as gradient, corner curvature, presence / absence of traffic lights), and the gradient of the current travel path. And information on the gradient of the road ahead. As the traveling environment information acquisition device 72, a communication system that transmits and receives various information such as traveling environment information to and from an external server can be used. In this case, for example, the vehicle position information by GPS is sent to the server, and the travel environment information (such as the current travel path gradient and the information on the gradient of the subsequent travel path) according to the vehicle position information is sent to the server. Receive from.

  In the vehicular travel control apparatus 1, if the first acceleration / deceleration travel pattern falls within the feasible region, the fuel consumption performance does not deteriorate due to engine braking. Set to deceleration travel pattern.

  On the other hand, in the case where the second acceleration / deceleration traveling pattern is applicable, the second acceleration that is recommended as it is is determined according to the gradient of the traveling path to a predetermined distance ahead of the vehicle. It is determined whether to perform inertial traveling with engine braking in the deceleration traveling pattern or to switch to the first acceleration / deceleration traveling pattern that can improve the fuel efficiency. The predetermined distance is a travel distance when the host vehicle reaches the set upper limit vehicle speed by acceleration when performing inertial travel without engine brake from the present time. In this case, it is assumed that the vehicle travel control device 1 is coasting in a state where the engine brake is not applied, and when the own vehicle reaches the set upper limit vehicle speed or is set by a change in the gradient of the travel path thereafter. If the vehicle starts to decelerate before reaching the upper limit vehicle speed, the acceleration / deceleration running pattern to be executed is switched to the first acceleration / deceleration running pattern that enables inertial running without engine braking. Here, the set upper limit vehicle speed in the acceleration / deceleration driving pattern is used. However, the set upper limit vehicle speed may be, for example, when performing inertial traveling only once to improve fuel efficiency (when the traveling state before and after inertial traveling does not matter). For example, the upper limit vehicle speed set in the vehicle speed control at that time may be used.

  The operation of the vehicle travel control device 1 will be described in detail based on the flowchart of FIG.

  The vehicle travel control device 1 first acquires information necessary for control (step ST1).

  Here, vehicle state information, driver operation amount information, and travel environment information are acquired. The vehicle state information includes vehicle speed (obtained from the vehicle speed detection device 71), longitudinal acceleration (obtained from the longitudinal acceleration sensor 73), lateral acceleration (obtained from the lateral acceleration sensor 74), and the like. The driver operation amount information includes an accelerator pedal operation amount (obtained from the accelerator opening sensor 75), a brake pedal operation amount (obtained from the brake opening sensor 76), and a steering wheel operation amount (obtained from the steering angle sensor 77). ) Etc. The travel environment information is information such as the gradient, corner curvature, and presence / absence of a traffic light on the current travel path and the travel path ahead, and is acquired from the travel environment information acquisition device 72.

  The vehicle travel control device 1 determines whether steady travel is being performed based on the acquired information (step ST2).

  It is determined whether the change in the vehicle speed so far (from now until a predetermined time or until a predetermined distance) is within a predetermined range (within a range where it can be determined that the vehicle is in steady driving). When an affirmative determination is made that there is, it can be determined that there is a high possibility of steady running. Further, it is determined whether or not the standard deviation of the average vehicle speed so far is within a predetermined value (a value that can be determined that the vehicle is in steady driving). If an affirmative determination is made that it is within the predetermined value, steady driving is performed. It can be judged that there is a high possibility that this has been done. In addition, it is determined whether the fluctuation amount of the operation of the accelerator pedal so far is within a predetermined value (a value that can be determined to be during steady running), and when an affirmative determination is made that it is within the predetermined value, It can be determined that there is a high possibility that the vehicle has traveled normally. Further, it is determined whether or not the speed ratio of the transmission 20 so far is within a predetermined value (a value that can be determined to be during steady running), and when an affirmative determination is made that it is within the predetermined value, It can be determined that there is a high possibility that the vehicle has been driven. Here, if the same gear position remains, it is determined that there is a high possibility of steady running. The vehicle travel control device 1 determines that all of these are affirmative, and that steady travel is being performed if the shift position of the transmission 20 is the D range (drive range). Here, in this step ST2, it may be used as a material for determining whether or not constant speed traveling control such as cruise control is being performed. If constant speed traveling control is being performed, steady traveling is being performed. to decide.

  The fact that the host vehicle is traveling normally is one of the feasible requirements for the eco-run according to the subsequent acceleration / deceleration traveling pattern. For this reason, when it is determined in step ST2 that the vehicle traveling control device 1 is in steady traveling, the vehicle traveling control device 1 determines whether or not the first or second acceleration / deceleration traveling pattern can be executed next. (Step ST3).

  The determination in step ST3 is made based on the current vehicle state of the host vehicle, the current and future travel environment. Here, the current vehicle speed and the gradient of the travel path are compared with the map of FIG. 2 to determine whether the vehicle is in the acceleration / deceleration travel pattern execution prohibition region, or the first or second acceleration / deceleration travel pattern. It is determined whether it falls under the executable area.

  Here, even if the current vehicle state and the driving environment are suitable for the execution of the first or second acceleration / deceleration driving pattern, the driving environment ahead of the current vehicle condition and the driving environment is not necessarily the execution of the first or second acceleration / deceleration driving pattern. Not always suitable. Driving with the acceleration / deceleration driving pattern increases the fuel efficiency performance by repeating acceleration driving and deceleration driving several times, or by running each of the predetermined driving distances of acceleration driving and deceleration driving. Therefore, a travel distance sufficient to obtain a desired fuel efficiency improvement effect is required. However, driving in the acceleration / deceleration driving pattern is not performed on corners or steep road surfaces that cannot keep within the predetermined vehicle speed range (in this case, the upper limit vehicle speed range and the lower limit vehicle speed range). When there is a corner or a steep road surface before reaching a preferable travel distance, it is not possible to continue traveling in the acceleration / deceleration travel pattern. For this reason, even if the current vehicle state and driving environment are suitable for the execution of the first or second acceleration / deceleration driving pattern, a predetermined distance of the own vehicle (in this case, an effect of improving a desired fuel consumption performance is obtained). When there is a corner or a steep road surface on the previous road, it is determined that it corresponds to the execution prohibited area of the acceleration / deceleration driving pattern.

  When the vehicle travel control device 1 determines that the first or second acceleration / deceleration travel pattern can be executed in step ST3, the vehicle travel control device 1 determines whether or not the current situation corresponds to the execution requirements for the deceleration travel. Is performed (step ST4). For example, when the acceleration / deceleration travel pattern is set to start from the deceleration travel, if it is now the start of travel in the acceleration / deceleration travel pattern, it is determined that the execution requirement for the deceleration travel is met. On the contrary, when the acceleration / deceleration driving pattern is set to start from acceleration driving, if it is now the start of driving in the acceleration / deceleration driving pattern, the acceleration driving execution requirement is met. Determined. Also, a setting that determines the travel mode at the start of the acceleration / deceleration travel pattern according to the current vehicle speed (for example, start from deceleration travel if the current vehicle speed is close to the set upper limit vehicle speed, and start from acceleration travel if the current vehicle speed is close to the set lower limit vehicle speed. In the case of (setting), it is determined whether or not it meets the execution requirement of the deceleration traveling according to the vehicle speed. Further, when the vehicle is already decelerating, it corresponds to the requirement for executing the decelerated driving until the set lower limit vehicle speed is reached.

  If the vehicle travel control device 1 satisfies the execution requirements for the deceleration travel, the vehicle travel control device 1 determines whether inertia travel with an engine brake is recommended during the travel (step ST5). Here, if the first acceleration / deceleration driving pattern is currently selected, it is determined that inertial driving without engine braking is recommended. If the second acceleration / deceleration driving pattern is selected, engine braking is performed. Judge that inertial running is recommended. If the coasting without the engine brake is recommended, the vehicle travel control apparatus 1 proceeds to step ST8 described later, and executes the coasting without the engine brake as recommended.

  The vehicle travel control device 1 assumes that coasting without engine brake is applied if coasting with engine brake is recommended, and sets the vehicle speed to the set upper limit vehicle speed from the present at the time of execution. The travel distance L to reach is calculated (step ST6). The travel distance L can be obtained from Equation 1 below.

  In equation 1, “V0” is the current vehicle speed, and “Vu” is the set upper limit vehicle speed. “A” is the acceleration of the vehicle, and can be obtained from the following Equation 2. The acceleration a is given as an example when the downhill road with the same gradient (θ) continues until the set upper limit vehicle speed Vu is reached. In Equation 2, “ρ” is the air density, “Cd” is the resistance coefficient, “A” is the front projection area, “V” is the vehicle speed, and “M” is the mass of the vehicle. One item of Equation 2 shows the effect of gravity acceleration g, two items show the effect of air resistance, and three items show the effect of rolling resistance.

  Formula 1 is obtained by substituting the time t until the set upper limit vehicle speed Vu of Formula 4 is reached into the formula (Formula 3) of the travel distance L below.

  Subsequently, the vehicular travel control device 1 assumes that the coasting without the engine brake has been executed, and the traveling by the gradient of the travel path until the traveling distance L (the set upper limit vehicle speed) is reached by the coasting. It is determined whether or not the host vehicle starts to decelerate before the distance L (set upper limit vehicle speed) is exceeded (step ST7). If the gradient information is acquired in step ST1, it may be used, and if it is insufficient, the deficiency may be newly acquired. Here, it is determined whether or not the vehicle starts to decelerate, but there is a possibility that constant speed traveling may be performed even temporarily before the traveling distance L (the set upper limit vehicle speed) is exceeded in this inertial traveling. In step ST7, it may be determined whether or not the host vehicle starts to travel at a constant speed before the travel distance L (set upper limit vehicle speed) is exceeded.

  And if this vehicle travel control apparatus 1 begins to decelerate before the travel distance L (set upper limit vehicle speed) is exceeded (if it starts to travel at a constant speed), the first acceleration / deceleration travel pattern is used as the acceleration / deceleration travel pattern. And coasting without engine brake is executed (step ST8). At that time, the vehicle travel control device 1 sends a command to the transmission ECU 102 to release the power connection / disconnection portion (at least one of the lockup clutch 35 and the input clutch C1) of the power transmission device, and the engine. Prevent the brakes from working. Here, the engine ECU 101 is instructed to put the engine 10 into a fuel cut state. As a result, the vehicle can improve the fuel efficiency without exceeding the set upper limit vehicle speed as compared with the case where the inertia running with the engine brake is executed.

  Here, since this vehicle starts decelerating when it reaches the set upper limit vehicle speed or before it, this inertial running without engine braking can be continued without changing the control mode. On the other hand, when coasting with engine brake is executed, acceleration traveling starts after reaching the set lower limit vehicle speed. Therefore, the vehicle travel control device 1 can greatly improve the fuel efficiency compared to the case where the inertia traveling with the engine brake is executed.

  On the other hand, if it is determined in step ST7 that the vehicle travel control device 1 does not start to decelerate before the travel distance L (set upper limit vehicle speed) is exceeded (if it is determined not to start constant speed travel), that is, travel. If the acceleration continues even when the distance L (the set upper limit vehicle speed) is reached, coasting with engine brake is executed as recommended (step ST9). At this time, the power connecting / disconnecting portion (the lock-up clutch 35 and the input clutch C1) of the power transmission device is kept in a completely engaged state. Here, the engine ECU 101 is instructed to put the engine 10 into a fuel cut state. The vehicle decelerates while improving fuel efficiency due to its inertial running.

  Meanwhile, when it is determined in step ST4 that the acceleration travel requirement is satisfied, the vehicle travel control device 1 performs the acceleration travel according to the selected first or second acceleration / deceleration travel pattern. Execute (step ST10).

  When it is determined in step ST2 that steady traveling is not being performed, or when it is determined in step ST3 that execution of the first or second acceleration / deceleration traveling pattern is impossible, the vehicle travel control device 1 is Then, normal control is performed by prohibiting execution of the acceleration / deceleration running pattern (step ST11). The normal control is well-known vehicle speed control different from, for example, acceleration / deceleration traveling pattern control, and performs any one of constant speed traveling, deceleration traveling, and acceleration traveling. For example, constant speed traveling and decelerating traveling are performed in an execution prohibition region of an acceleration / deceleration traveling pattern on an uphill road. During the deceleration traveling, the engine 10 may be in a fuel cut state. In addition, acceleration traveling is performed in the execution prohibition region of the acceleration / deceleration traveling pattern on the downhill road. During the acceleration running, the engine 10 may be in a fuel cut state. In addition, you may return to a driver | operator's manual operation instead of this normal control.

  As described above, the vehicular travel control device 1 can perform inertial running without using the engine brake as much as possible, so that it is possible to suppress energy discard by the engine brake as much as possible. Fuel efficiency can be improved.

  Here, in this example, the lock-up clutch 35 and the input clutch C1 are cited as the power connection / disconnection part of the power transmission device. However, as the power connection / disconnection part, other things (clutch etc.) are the engine 10 and the drive wheel. If it is provided between WL and WR, this may be a control target related to generation of engine brake.

  As described above, the vehicular travel control apparatus according to the present invention is useful for a technique for improving fuel consumption performance.

DESCRIPTION OF SYMBOLS 1 Vehicle travel control apparatus 10 Engine 20 Transmission 35 Lockup clutch 71 Vehicle speed detection apparatus 72 Travel environment information acquisition apparatus C1 Input clutch (power connection / disconnection part)
101 engine ECU
102 Transmission ECU
WL, WR Drive wheel

Claims (3)

In a vehicle travel control device that controls a travel state of a vehicle including an engine as a power source and a power transmission device that transmits power of the engine to driving wheels,
Grasping the gradient of the travel path to a predetermined distance ahead of the vehicle and transmitting power between the engine and the drive wheel when the vehicle may continue to accelerate even at the predetermined distance When there is a possibility that the vehicle will start to decelerate until it exceeds the predetermined distance, by performing inertial running with the fuel supply amount reduced to the engine or with the fuel supply stopped, A vehicle travel control device that performs the inertial traveling by controlling a power connection / disconnection portion of the power transmission device so that power transmission between the engine and the driving wheel is cut off.   Determining whether to select inertial driving in a state where the power transmission is possible or inertial driving in a state where the power transmission is impossible when the host vehicle is traveling on a downhill road The vehicle travel control device according to claim 1.   During traveling with an acceleration / deceleration traveling pattern in which acceleration traveling from the set lower limit vehicle speed to the set upper limit vehicle speed and deceleration traveling from the set upper limit vehicle speed to the set lower limit vehicle speed are alternately repeated, the power transmission is impossible. The vehicle travel control device according to claim 2, wherein the predetermined distance is a travel distance until the host vehicle reaches the set upper limit vehicle speed as the inertial travel is performed.

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