Drive force control system for a vehicle

Abstract

Drive force control system for a vehicle (Ve) with a machine (3), drive wheels (2) and an automatic transmission (4) which transmits a torque between the machine and the drive wheels, wherein this has a control device (8) which is configured such that this (i) controls a propulsive force of the vehicle (Ve) based on a vehicle speed and an amount of accelerator pedal actuation of the vehicle (Ve); (ii) stores an acceleration characteristic which defines a relationship between a re-acceleration time acceleration and the vehicle speed, wherein the re-acceleration time acceleration is used as a control index when the vehicle is moving while it is re-accelerating after a deceleration run, (iii) the re-acceleration time acceleration according to a current vehicle speed based on vehicle driving data (Ve) obtained before the deceleration run and the acceleration characteristic; (iv) a transmission ratio of the automatic transmission (4) which can realize the re-acceleration time acceleration, based on the obtained re-acceleration time acceleration, before the re-acceleration drive is started; (v) estimates, based on the driving data obtained during the acceleration run, a desired, expected vehicle speed to be achieved during the re-acceleration run prior to the deceleration run; and (vi) the re-acceleration time acceleration according to the current vehicle speed based on the current vehicle speed and the estimated expected vehicle speed, characterized in that the control device (8) is configured such that this (i) stores a plurality of acceleration characteristic curves on which the re-acceleration time acceleration is determined according to the vehicle speed, (ii) selects one of the acceleration characteristics based on the expected vehicle speed; and (iii) the re-acceleration time acceleration according to the current vehicle speed based on the current vehicle speed, the expected vehicle speed and the selected acceleration characteristic curve.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to a drive force control system for a vehicle which controls a drive force of the vehicle by changing the gear ratio of an automatic transmission while the vehicle is driving, while it is decelerating. 2. Description of the state of the art

[0002] Japanese patent publication JP 2007-170444 A describes a drive force control system for a vehicle that performs a control to prevent upshifting when the vehicle's accelerator pedal is rapidly released and a deceleration support control, including a control to perform downshifting when the vehicle is suddenly decelerated. The drive force control system described in JP 2007-170444 A, as stated above, is configured to determine the conditions of the deceleration support control described above based on the driving environment and vehicle driving conditions.The system determines, for example, whether to execute the deceleration support control and a control level to use when the deceleration support control is executed, based on factors such as the distance between the vehicle and a vehicle ahead, the gradient of the road surface, and / or the driver's driving tendency, inclination, or behavior. In a control example described in JP 2007-170444 A cited above, if the driver's driving tendency is sporty, the automatic transmission may downshift to a lower gear position during the execution of the deceleration support control. A sporty driving tendency corresponds to a driving tendency...a driving style in which great emphasis is placed on the vehicle's performance and a quick response of the vehicle to driving input is required.

[0003] Japanese patent publication JP 2003-211999 A describes a driving control system that causes a vehicle to automatically follow a vehicle ahead. The driving control system described in JP 2003-211999 A records driving data, including vehicle behavior, driving environment, and power steering input, while the vehicle is in motion. The driver's driving tendency or behavior (multiple regression coefficient) is then determined by performing a multiple regression analysis on this driving data. Furthermore, the system is configured to automatically follow the vehicle ahead by setting a target acceleration / deceleration based on the driving tendency.

[0004] Furthermore, a drive force control system described in Japanese patent publication number JP 2002-139135 A is configured to calculate a recommended or suggested gear ratio based on a road driving environment, calculate the optimal gear ratio based on the recommended gear ratio, the driver's intention to change the gear ratio, and the actual gear ratio, and change the optimal gear ratio at a rate of change determined by the difference between the recommended gear ratio and the actual gear ratio.

[0005] As described above, the control system described in JP 2007-170444 A estimates or determines the driver's driving tendency while the vehicle is in motion. When the driving tendency corresponds to a sporty driving tendency, the automatic transmission downshifts to a lower gear position, compared to when the driving tendency does not correspond to a sporty driving tendency, for example, when the vehicle is decelerating before a curve or intersection. Downshifting in this manner during deceleration can improve acceleration performance when the vehicle accelerates again after braking.

[0006] The control system described in JP 2007-170444 A, however, uniformly sets the gear position during deceleration at a point before a curve or intersection, depending on whether the driver's driving tendency corresponds to a sporty driving tendency, and performs a downshift to achieve the gear position set in this way. Furthermore, the driving tendency, which is based on an estimate, inevitably includes individual differences or estimation errors. Therefore, the gear position or gear ratio achieved after downshifting may not be adequate or suitable. For example, if downshifting is insufficient, a further downshift may occur when the driver depresses the accelerator pedal to accelerate the vehicle after turning into the curve. That is, the actual driving force generated may be relative to that intended by the driver.The desired required driving force may be insufficient. Consequently, the driver may experience a strange or unpleasant sensation, or may feel that the acceleration performance or the acceleration sensation is not good.

[0007] Furthermore, DE 10 2010 024 045 A1 discloses a method and a device for selecting a gear in an automatic transmission for a traction phase following a coasting phase of a motor vehicle. In this method, a moving average value of the engine speed and / or the tractive force level is calculated during a traction phase prior to the coasting phase, depending on the respective speed and gradient, and is used to determine at least one gear selection of the automatic transmission for the traction phase following the respective coasting phase.

[0008] German patent DE 10 2004 036 086 A1 describes how, in a motor vehicle's cruise control system, a desired acceleration is selected from data from the accelerator pedal and a control element for selecting a desired acceleration mode. Using the control element, the driver selects the mode, for example, sporty or comfortable, in which a speed difference between the actual speed and the desired speed should be compensated. The compensation of the speed difference is also achieved via the accelerator pedal position.

[0009] Furthermore, WO 2008 / 000382A1 discloses a method for controlling the gear ratio of a continuously variable transmission (CVT). An accelerator pedal position and the current vehicle speed are recorded, and a gear ratio gradient is determined taking these into account. A target gear ratio is calculated as the sum of the current gear ratio and a gear ratio change value, and the CVT is adjusted accordingly. SUMMARY OF THE INVENTION

[0010] The aforementioned problems and the resulting task are solved by the subject matter of claim 1. Advantageous embodiments of the invention are the subject matter of the dependent claims that follow.

[0011] The present invention was conceived in view of the technical problems described above and provides a drive force control system for use in a vehicle on which an automatic transmission is installed, wherein the system sets a suitable gear position (gear ratio) which reflects the intention of the driver and the driving tendency, for a re-acceleration drive of the vehicle in a situation in which the vehicle is re-accelerated after it has decelerated.

[0012] According to one aspect of the present disclosure, a drive force control system is provided for a vehicle comprising a machine, drive wheels, and an automatic transmission which transmits torque between the machine and the drive wheels. The drive force control system includes a control device. The control device is configured to: (i) control a drive force of the vehicle based on a vehicle speed and an amount of accelerator pedal actuation by the vehicle;(ii) stores an acceleration characteristic that defines a relationship between a re-acceleration time acceleration and the vehicle speed, wherein the re-acceleration time acceleration is used as a control index when the vehicle is moving while re-accelerating after a deceleration run; (iii) obtains the re-acceleration time acceleration according to a current vehicle speed based on vehicle driving data obtained before the deceleration run and the acceleration characteristic; and (iv) sets a gear ratio of the automatic transmission that can realize the re-acceleration time acceleration based on the obtained re-acceleration time acceleration before the re-acceleration run is initiated.

[0013] In the drive force control system described above, the control device is further configured such that it: (i) estimates, based on the driving data obtained during the acceleration run, a desired, expected vehicle speed to be achieved during the re-acceleration run prior to the deceleration run; and (ii) obtains the re-acceleration time acceleration according to the current vehicle speed based on the current vehicle speed and the estimated expected vehicle speed.

[0014] In the drive force control system described above, the control device is further configured to: (i) store a plurality of acceleration characteristics on which the re-acceleration time acceleration is determined according to the vehicle speed; (ii) select one of the acceleration characteristics based on the expected vehicle speed; and (iii) obtain the re-acceleration time acceleration according to the current vehicle speed based on the current vehicle speed, the expected vehicle speed and the selected acceleration characteristic.

[0015] In the drive force control system described above, the control device can be configured to: (i) store a vehicle speed and acceleration when the re-acceleration run is started, and (ii) update the acceleration characteristic curve.

[0016] In the drive force control system described above, the control device can be configured to: (i) obtain the re-acceleration time acceleration using an average value of the re-acceleration time acceleration or an average value of the expected vehicle speed from re-acceleration runs performed multiple times in the past; and (ii) adjust the gear ratio of the automatic transmission that can achieve the obtained re-acceleration time acceleration.

[0017] In the drive force control system described above, the control device can be configured to set a maximum vehicle speed, which is recorded by the vehicle from a time when the expected vehicle speed is not set before the deceleration run is started, as the expected vehicle speed.

[0018] In the vehicle drive force control system according to the invention, when the vehicle is re-accelerated after deceleration, the transmission ratio (or gear position) of the automatic transmission is adjusted until the time the re-acceleration begins. This adjustment enables the vehicle to accelerate with the aforementioned re-acceleration time acceleration, i.e., the acceleration expected by the driver. The re-acceleration time acceleration corresponds to a control index for use during the re-acceleration following deceleration, and it represents an estimated acceleration that the driver intends to achieve during re-acceleration, or an acceleration expected by the driver.The re-acceleration time acceleration is determined based on a pre-stored acceleration characteristic and vehicle driving data acquired before the deceleration run. The acceleration characteristic, which defines the relationship between the re-acceleration time acceleration and the vehicle speed, can be pre-stored. The vehicle driving data can include physical quantities such as vehicle speed, acceleration, the gear ratio of the automatic transmission, and engine speed, representing the vehicle's driving conditions.

[0019] Accordingly, with the drive force control system for the vehicle of this invention, when the vehicle is re-accelerated after deceleration, a shift control of the automatic transmission can be completed to adjust the gear ratio that allows the vehicle to accelerate with the re-acceleration time acceleration before the re-acceleration drive is initiated. Furthermore, the re-acceleration time acceleration, as described above, is derived from the driving data obtained before the deceleration drive and the acceleration characteristics of the vehicle; thus, the re-acceleration time acceleration can be used as a control index of the shift control, reflecting the driver's intention, driving tendency, etc.Therefore, when the re-acceleration phase begins after the deceleration phase, the gear ratio capable of providing the necessary driving force for re-acceleration has already been set in the automatic transmission. Furthermore, it is assumed that the gear ratio set at this time allows the vehicle to accelerate with the acceleration desired or demanded by the driver.

[0020] For example, when the vehicle is driving around a curve, the automatic transmission can be pre-selected to a gear ratio (gear position) suitable for the vehicle's re-acceleration as it exits the curve, or for the re-acceleration phase during deceleration, from the point where the vehicle enters the curve until it is fully engaged in the turn. Accordingly, as the vehicle enters and navigates the curve, it can be decelerated appropriately to maintain a stable cornering position while preserving high traction.Then, when the vehicle leaves the curve and begins to accelerate again, the automatic transmission has been downshifted to a state in which a high driving force can be maintained.

[0021] Therefore, according to the vehicle's drive force control system of this invention, further downshifting is prevented during re-acceleration following deceleration to compensate for a lack of drive force due to insufficient downshifting during deceleration, and the vehicle can accelerate appropriately. Consequently, it is less likely or improbable that the driver will perceive a strange or unpleasant sensation or jolt, and the vehicle's acceleration performance and the sensation of acceleration can be improved. BRIEF DESCRIPTION OF THE IMAGES

[0022] Features, advantages and the technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying figures, in which the same reference numerals denote the same elements, and wherein: Fig. 1 is a view showing an example of the configuration of a vehicle which is to be controlled by a drive force control system for a vehicle according to this invention, and showing a control system; Fig. 2 is a flowchart which is useful for explaining an example of a basic drive force control carried out by the drive force control system for the vehicle of the invention; Fig. 3 is a view which is useful for explaining the relationship between the “reacceleration time acceleration” and the vehicle speed obtained in order to obtain the “expected vehicle speed” and the “reacceleration time acceleration” in the drive force control of the invention; Fig. 4. A view that is useful for explaining a correlation line (approximation line) which is in Fig. The relationship shown in section 3 is represented; Fig. 5 is a view which is useful for explaining an example of a control characteristic map for obtaining the “reacceleration time acceleration” in the drive force control of the invention; Fig. 6 is a view which is useful for explaining a control for obtaining a “realizable acceleration” and a gear position (transmission ratio) which can provide the realizable acceleration in the drive force control of this invention; Fig. 7A and Fig. 7B are views which are useful to explain the behavior (such as vehicle speed, acceleration and engine speed) of the vehicle when the drive force control of the invention is carried out; Fig. 8 is a block diagram which is useful for explaining the configuration of a control device which forms the drive force control system for the vehicle of the invention; Fig. 9A and Fig. 9B are views which are useful to explain the behavior (such as vehicle speed, acceleration and engine speed) of the vehicle when the drive force control of the invention is carried out on a vehicle on which a continuously variable transmission is installed; Fig. 10 is a view which is useful for explaining a further control example when the drive force control of the invention is carried out on the vehicle on which the continuously variable transmission is installed; Fig. 11A and Fig. 11B are views which are useful to explain a further control example when the drive force control of the invention is carried out; Fig. 12A and Fig. Figure 12B shows views which are useful for explaining yet another control example when the drive force control of the invention is carried out; Fig. 13 is a view which is useful for explaining yet another control example when the drive force control of the invention is carried out; Fig. 14 is a view which is useful for explaining a further control example when the drive force control of the invention is carried out; Fig. 15 is a view which serves to explain a further example of the in Fig. The control map shown in section 5 is useful; Fig. 16 is a view which serves to explain a further example of the in Fig. The control map shown in section 5 is useful; Fig. 17 is a flowchart which is useful for explaining a further example of the drive force control carried out by the drive force control system for the vehicle of the invention; Fig. 18 is a time diagram which is used to illustrate an example of obtaining the “expected vehicle speed” in drive force control according to the in Fig. The flowchart shown in 17 is useful; Fig. 19 is a flowchart which is useful for explaining a further example of the drive force control carried out by the drive force control system for the vehicle of the invention; Fig. 20 is a flowchart which is useful for explaining a further example of the drive force control carried out by the drive force control system for the vehicle of the invention; Fig. 21 is a view which is useful for explaining a procedure for calculating an approximation curve of driving data in connection with a control for weighting driving data in order to obtain the ‘expected vehicle speed’ and the ‘re-acceleration time acceleration’; Fig. 22 is a view which is useful for explaining the effect of weighting the driving data; Fig. 23 is a view which is useful to explain an example in which a coefficient (slope) which specifies a correlation line for obtaining the “expected vehicle speed” and the “re-acceleration time acceleration” is controlled by learning in the drive force control of the invention; Fig. 24 is a view which is useful for explaining a further example in which a coefficient (slope) which specifies a correlation line for obtaining the “expected vehicle speed” and the “re-acceleration time acceleration” is controlled by learning in the drive force control of the invention; and Fig. 25 is a flowchart which is useful for explaining a further example of the drive force control carried out by the drive force control system for the vehicle of the invention. DETAILED DESCRIPTION OF EXECUTION FORMS

[0023] An embodiment of the invention is described below with reference to the figures. An automatic transmission is installed on a vehicle to which this invention can be applied. This transmission is capable of transmitting power generated by a machine to the drive wheels while the rotational speed is varied. The automatic transmission of the vehicle to which the invention is applied can be a continuously variable transmission, such as a belt-driven or band-driven CVT or a toroidal CVT, which is capable of continuously changing the gear ratio. This invention can also be applied to a hybrid vehicle with a power distribution device that combines and distributes the power generated by a machine and a motor.This means that the power distribution device included in the hybrid vehicle serves as a so-called electric continuously variable transmission, and the electric continuously variable transmission can be considered a type of automatic transmission according to this invention.

[0024] As an example of the vehicle to which this invention can be applied, the configuration of a vehicle in which an automatic transmission is installed on the outside of a machine, and its control system in Fig. 1 shown. The in Fig. Vehicle Ve shown has front wheels 1 and rear wheels 2. In the case of the vehicle shown in Fig. In the example shown, the vehicle Ve is configured as a rear-wheel-drive vehicle in which power generated by a machine (ENG) 3 is transmitted via an automatic transmission (AT) 4 and a differential 5 to the rear wheels 2 to generate a driving force. The vehicle Ve, to which this invention can be applied, can be a front-wheel-drive vehicle in which power generated by the machine 3 is transmitted to the front wheels 1 to generate a driving force. The vehicle Ve can also be an all-wheel-drive vehicle in which power generated by the machine 3 is transmitted to both the front wheels 1 and the rear wheels 2 to generate a driving force.

[0025] Machine 3 includes, for example, an electronically controlled throttle valve or electronically controlled fuel injection devices and an airflow sensor that detects the flow rate of the intake air. In the case of the Fig. In the example shown in Figure 1, the machine 3 comprises an electronic throttle valve 6 and an airflow sensor 7. Accordingly, it is possible to automatically control the output of the machine 3 by electrically controlling the operation of the electronic throttle valve 6, for example, based on data acquired from an accelerator pedal position sensor 9 described later.

[0026] The automatic transmission 4 is located on the outside of the machine 3 to transmit an output torque from the machine 3 towards the drive wheels while the rotational speed is changed. The automatic transmission 4 is a conventional automatic transmission with two or more gear positions and consists of a planetary gear train and clutch and brake mechanisms. By controlling the operation of the clutch and brake mechanisms, the gear position (or gear ratio) to be created or set in the automatic transmission 4 can be automatically controlled.

[0027] A control device 8 is provided for controlling the output of machine 3 and for shifting gears in the automatic transmission 4. The control device 8 corresponds to an electronic control unit (ECU), which is primarily based on a microcomputer, for example. Machine 3 is connected to the control device 8 in such a way that they can communicate with each other to control machine 3. Furthermore, the automatic transmission 4 is connected to the control device 8 via a hydraulic control system (not shown) in such a way that they can communicate with each other to control the transmission 4. While in the example of Fig. 1 where a control device 8 is provided, two or more control devices may be provided for corresponding devices or instruments, or these may, for example, be provided for corresponding control contents.

[0028] The control device 8 described above is configured to receive these detection signals from various sensors on corresponding components of the vehicle Ve and information signals from various vehicle-side devices. For example, the control device 8 is configured to receive these detection signals from the aforementioned airflow sensor 7, the accelerator pedal position sensor 9, which detects the amount of accelerator pedal depressor or pedal position, a brake sensor (or brake switch) 10, which detects the amount of brake pedal depressor, a machine speed sensor 11, which detects the rotational speed of an output shaft 3a of the machine 3, an output shaft speed sensor 12, which detects the rotational speed of an output shaft 4a of the automatic transmission 4, and a vehicle speed sensor 13, which obtains the vehicle speed by detecting the rotational speeds of the respective wheels 1, 2.Furthermore, the control device 8 is configured to perform these calculations using the recorded data, previously stored data, etc., and to output control command signals based on the results of the calculations.

[0029] When the vehicle Ve, configured as described above, accelerates again after deceleration, a downshift can be performed in response to the driver pressing the accelerator pedal, as described above. If the automatic transmission 4 does not downshift appropriately during deceleration, the driving force at the time of re-acceleration will be insufficient, and a downshift to create an even lower gear position (or to increase the gear ratio) would be performed when the vehicle Ve begins to accelerate again. Consequently, the driver may experience a strange or unpleasant sensation, or may not perceive a good sense of acceleration. Furthermore, the intention and driving tendency, or rather, the vehicle's behavior, will change.The driver's driving behavior depends on individual differences between drivers, the driving environment, etc. Nevertheless, if the automatic transmission 4 downshifts uniformly during deceleration, as described above, the driving force and acceleration desired by the driver cannot be obtained when the vehicle Ve begins to accelerate again.

[0030] Therefore, the control device 8 is configured to appropriately re-accelerate the vehicle Ve by performing drive force control on the vehicle Ve, so that the driver's intention and driving tendency are reflected by the control. In particular, the control device 8 is configured to determine a "re-acceleration time acceleration" as a control index for use when the vehicle Ve is re-accelerated after deceleration, and to adjust the gear ratio of the automatic transmission 4 to achieve the "re-acceleration time acceleration" determined in this way before the vehicle Ve begins to re-accelerate.The "re-acceleration time acceleration," which corresponds to the control index for use when the vehicle re-accelerates after deceleration, represents an estimated acceleration desired or expected by the driver at the time Ve re-accelerates. The "re-acceleration time acceleration" is derived from an acceleration characteristic and vehicle driving data Ve. The acceleration characteristic, which determines the relationship between the "re-acceleration time acceleration" and the vehicle speed, is pre-stored as an arithmetic expression or a map.The vehicle Ve's driving data includes physical quantities that specify the vehicle Ve's driving conditions, such as vehicle speed, acceleration, the gear ratio of the automatic transmission 4, and engine speed, and these are extracted from the driving history obtained before the current deceleration run. If the control device 8 is configured to clear this driving data when the ignition switch (or a master switch) is turned off, the driving history before the current deceleration run corresponds to the driving data history obtained from the time when the vehicle Ve's ignition switch is turned on for the current run and is described below with reference to . Fig. 2. The control described above is started for the first time, leading up to the present time.

[0031] A control operation carried out by the control device 8 is described in more detail below. Fig. Figure 2 is a flowchart useful for illustrating an example of a basic control system. First, it is determined whether the vehicle Ve's acceleration run is complete, that is, whether the vehicle Ve has finished a journey involving acceleration (step S1). For example, it can be determined whether the acceleration run is complete based on a reading from the vehicle speed sensor 13 or a longitudinal acceleration sensor (not shown). In step S1, it is determined that the "vehicle's acceleration run is complete" when the vehicle Ve's acceleration becomes zero, after it has been determined that the vehicle Ve is moving while accelerating, or when the vehicle Ve has transitioned to deceleration, during which the vehicle Ve's acceleration becomes less than or equal to zero. The same determination is made when the brake switch 10 is activated.Accordingly, in all cases other than those mentioned above, a negative decision (No) is made at step S1. A negative decision (No) is made, for example, if the vehicle has not accelerated since the start of this control system, if the vehicle is moving while being accelerated, or if the vehicle is moving in a stable state or at a constant speed.

[0032] If the vehicle Ve's acceleration run is complete and a positive decision (Yes) is made at step S1, the control device proceeds to step S2. At step S2, the expected vehicle speed Vexp and the gradient coefficient K are calculated and updated. Specifically, driving data (for example, the vehicle speed at the start of acceleration and the maximum acceleration during the acceleration run) of the vehicle Ve, which is stored during the acceleration run whose end was determined at step S1, is read out, and the expected vehicle speed Vexp and the gradient coefficient K are updated based on this driving data. When the driver operates the vehicle Ve, it can be assumed that the driver is driving the vehicle while maintaining a predetermined vehicle speed at all times.In the control system 8, the "expected vehicle speed" is defined as the vehicle speed pursued by the driver or the vehicle speed assumed to be desired by the driver. Generally, under the same driving conditions, the "expected vehicle speed" is higher when the driver's driving style becomes more sporty, placing greater emphasis on performance or handling than normal. Conversely, the "expected vehicle speed" is lower when the driver's driving style becomes more economical, placing greater emphasis on fuel efficiency than normal.The expected vehicle speed, Vexp, can be obtained based on the vehicle's driving history, Ve, which includes data such as vehicle speed, longitudinal acceleration, lateral acceleration, steering angle, road surface gradient, and vehicle attitude. The gradient coefficient, K, represents the slope or gradient of a correlation line used to determine the expected vehicle speed, as described later. The expected vehicle speed, Vexp, and the gradient coefficient, K, are described in more detail later.

[0033] If a negative decision (No) is made in step S1, the control device advances to step S3. In step S3, the last or previous values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained. That is, the expected vehicle speed Vexp and the gradient coefficient K, which were calculated and stored when the acceleration run last ended, are maintained until the current acceleration run ends. If the vehicle has not accelerated since this control cycle was started, the expected vehicle speed Vexp and the gradient coefficient K, which were stored when the ignition switch for the current run was turned on and this control cycle was initially started, are continuously maintained.In the arrangement where the expected vehicle speed Vexp and the gradient coefficient K are cleared when the ignition switch is turned off, preset initial values ​​of Vexp and K are read when the ignition switch is turned on and stored as the expected vehicle speed Vexp and the gradient coefficient K. Accordingly, if the vehicle Ve has not moved since the start of this control system while accelerating, or has been driven under acceleration, the respective initial values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained as described above. In the arrangement where the expected vehicle speed Vexp and the gradient coefficient K are stored at the time the ignition switch is turned off, if the vehicle has not moved since the start of this control system while accelerating, or has been driven under acceleration, the respective initial values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained as described above.The vehicle has been driven with an acceleration, the expected vehicle speed Vexp and the gradient coefficient K, which were stored when the ignition switch was last turned off, are read out and continuously maintained as described above.

[0034] Once the expected vehicle speed Vexp and the gradient coefficient K are updated in the preceding step S2, or the last or previous values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained in the preceding step S3, the control device 8 proceeds to step S4. In step S4, the re-acceleration time acceleration Gexp is obtained. If the vehicle Ve is decelerated without being stopped, it transitions to a re-acceleration driving state after the deceleration is complete. For example, if the vehicle Ve is traveling around a curve, it generally enters the curve while decelerating from a point before the curve. While in the curve, the vehicle Ve steers while decelerating or traveling at a constant speed. Subsequently, the vehicle accelerates again as it exits the curve.Therefore, it can be assumed that the driver accelerates the vehicle Ve to the expected vehicle speed Vexp when the vehicle Ve is re-accelerated after deceleration. Similarly, if there is a large vehicle speed difference ΔV (ΔV = Vexp - Vcur) between the expected vehicle speed Vexp and the current vehicle speed Vcur, it is assumed that the driver demands high acceleration to reduce the vehicle speed difference ΔV, and re-accelerates the vehicle Ve with the acceleration demanded in this way.

[0035] Assuming the above description, in step S4 the re-acceleration time acceleration Gexp is obtained from the vehicle speed difference ΔV between the expected vehicle speed Vexp and the current vehicle speed Vcur as an acceleration expected by the driver to be achieved at the time of re-acceleration. For example, in Fig. 3 and Fig. As shown in Figure 4, the results of driving tests, simulations, and the like demonstrate a negative correlation between the aforementioned "re-acceleration time acceleration" and the vehicle speed. If the x-axis represents the vehicle speed at the time the re-acceleration run begins, and the y-axis represents the acceleration (maximum acceleration over the ground) at that time, a correlation line (approximation line) of a linear function expressed as "y = a × x + b" can be derived. Fig. 4. The correlation line can also be obtained for each driving tendency of the driver, as shown in Fig. 3 is indicated by broken lines f1, f2, f3.

[0036] As described above, the "expected vehicle speed" is defined as a target vehicle speed that the driver wishes to achieve during acceleration. Therefore, the vehicle Ve does not need to accelerate further once the vehicle speed reaches the "expected vehicle speed"; consequently, the acceleration is assumed to be zero. Accordingly, the "expected vehicle speed" can be obtained by calculating an x-intercept (-b / a) at which the acceleration along the y-axis is zero.

[0037] The aforementioned acceleration above ground can be obtained, for example, as a differential value of acquired data from the output shaft speed sensor 12 or the vehicle speed sensor 13. While the acceleration can be obtained from an accelerometer installed on the vehicle Ve, noise may be present in the acquired acceleration data due to the influence of the vehicle Ve's position and the road surface inclination. Therefore, this control system uses the acceleration above ground obtained from the speed sensor, as described above.

[0038] Using the correlation between the "reacceleration time acceleration" and the vehicle speed, as described above, the relationship between the "reacceleration time acceleration" and the vehicle speed can be defined in advance as an acceleration characteristic of the vehicle Ve and stored in the control device 8. With the acceleration characteristic defined as a function of the vehicle speed, the "reacceleration time acceleration" can be calculated according to the "expected vehicle speed" and the "current vehicle speed" mentioned above.

[0039] The drive force control performed by the control device 8 makes it possible to store driving data at the time when the vehicle begins to accelerate again and to update the acceleration characteristic, which defines the relationship between the "reacceleration time acceleration" and the vehicle speed, as described above. The driving data stored in this case includes the vehicle speed and the vehicle's acceleration Ve when it begins to accelerate again. The acceleration characteristic, as described above, is stored, for example, as an acceleration curve that sets the "reacceleration time acceleration" according to the vehicle speed. The acceleration curve corresponds, in particular, to a correlation line (approximation line) which is defined in Fig. 4 is denoted as “y=a×x+b”.

[0040] Furthermore, the "re-acceleration time acceleration" can be calculated according to the "expected vehicle speed" and the "current vehicle speed," for example, from a Fig. The control map shown in Figure 5 can be obtained. That is, using the correlation described above between the "re-acceleration time acceleration" and the vehicle speed, which is obtained from the driving history or driving information during a previous acceleration run, the relationship between the "re-acceleration time acceleration" and the vehicle speed is defined in advance as an acceleration characteristic of the vehicle Ve, and this can be considered the one shown in Figure 5. Fig. The control characteristic map shown in section 5 is stored in the control device 8.

[0041] In Fig. Figure 5 specifies a straight line f representing an acceleration characteristic that defines the relationship between the "reacceleration time acceleration" and the vehicle speed, and this corresponds to the correlation line "y=a×x+b" described above. The slope of this straight line f represents the gradient coefficient K. On the straight line f, the vehicle speed at which the acceleration over the ground becomes zero, i.e., the x-intercept or y-intercept of the line f, corresponds to the "expected vehicle speed". Similarly, in Fig. 5. The re-acceleration time acceleration Gexp can be obtained by assigning the current vehicle speed Vcur to a comparison expression, which is defined by the straight line f, which passes through the expected vehicle speed Vexp obtained in the preceding step S2, and the gradient coefficient K.

[0042] Furthermore, two or more straight lines f can be, like a straight line fs and a straight line fm, as in Fig. 5, specified for each “expected vehicle speed,” as indicated above, or set according to the driving tendency. In this case, a specific straight line f is selected from the two or more lines based on the driving profile obtained during the previous acceleration run and determined as a correlation line. At the same time, the “expected vehicle speed” is obtained as an X-intercept or axis segment of the selected line f. The “expected vehicle speed” determined in this way, based on the profile during the previous acceleration run, reflects the driving tendency that emerged during the previous acceleration run.Then the "re-acceleration time acceleration" is obtained, for example, based on the "expected vehicle speed" obtained in the manner described above and the "current vehicle speed" obtained as the measured value from vehicle speed sensor 13. As in . Fig. As shown in Figure 5, the "re-acceleration time acceleration" is greater when the difference between the "expected vehicle speed" and the "actual vehicle speed" is larger. Furthermore, while the sporty driving tendency is stronger as one driving tendency type, the straight line fs, which represents the higher "expected vehicle speed," is selected, and the "re-acceleration time acceleration" obtained based on this line fs is larger. Conversely, while the economical driving tendency is stronger as another driving tendency type, the straight line fm, which represents the lower "expected vehicle speed," is selected, and the "re-acceleration time acceleration" obtained based on this line fm is smaller.

[0043] Once the re-acceleration time-acceleration Gexp obtained in step S4 as described above is obtained, the gear position of the automatic transmission 4 that can achieve the re-acceleration time-acceleration Gexp is obtained (step S5). That is, the optimal gear position set for the automatic transmission 4 is obtained, so that the vehicle Ve travels with the re-acceleration time-acceleration Gexp. An example of a procedure for obtaining the gear position is given in Fig. Figure 6 shows that the achievable acceleration Gable is set first. The realizable acceleration Gabl can be calculated using the following formula: Gabl = (Te max ×gR) / W are calculated, where Te max where R corresponds to the maximum value of the machine's output torque, W to the driving resistance, W to the vehicle's weight, and g to the gear ratio. As in Fig. As shown in Figure 6, the achievable acceleration G is calculated for each gear position of the automatic transmission 4.

[0044] Fig. Figure 6 provides an example where the automatic transmission 4 corresponds to an eight-speed forward transmission with eight forward gear positions. In the case of the Fig. In example 6, the highest gear position (fifth gear in the example of) is shown. Fig. 6) from the gear positions (the second, third, fourth and fifth gears in the example of Fig. 6), which are capable of achieving the "reacceleration time acceleration", are selected with reference to the "reacceleration time acceleration" obtained from the "expected vehicle speed" and the "current vehicle speed". That is to say, in Fig. 6 is the re-acceleration time acceleration Gexp, defined as the intersection point between the correlation line through which the expected vehicle speed Vexp passes and the straight line representing the current vehicle speed Vcur. The point representing the re-acceleration time acceleration Gexp is located between the achievable acceleration Gabl of fifth gear and the achievable acceleration Gabl of sixth gear. This means that if the engine 3 is generating maximum torque, the re-acceleration time acceleration Gexp cannot be achieved if the automatic transmission 4 is shifted into any gear position (sixth, seventh, or eighth gear) greater than or equal to sixth gear. Similarly, in the Fig. In the example shown in Figure 6, the fifth gear is selected as the highest gear from the gear positions (from fifth gear to second gear) of the automatic transmission 4 that can realize the re-acceleration time acceleration Gexp and are less than or equal to the fifth gear.

[0045] If the gear position (gear ratio) of the automatic transmission 4, which can realize the re-acceleration time-acceleration Gexp, is calculated at step S5, it is determined whether the vehicle Ve is moving while decelerating (step S6). For example, based on a reading from the vehicle speed sensor 13 or a longitudinal acceleration sensor (not shown), an actuation signal from the brake switch 10, or the like, it can be determined whether the vehicle Ve is moving while decelerating. If the vehicle Ve is not decelerating and a negative decision (No) is made at step S6, the control device 8 initially terminates this routine without performing any subsequent control action.

[0046] If, on the other hand, the vehicle Ve decelerates and a positive decision (Yes) is made at step S6, the control device 8 proceeds to step S7. At step S7, it is determined whether the gear position currently created in the automatic transmission 4 corresponds to a higher gear position than the gear position calculated in the preceding step S5, that is, whether the gear ratio of the current gear position is lower than the gear ratio of the calculated gear position. If the current gear position corresponds to a lower gear position than the calculated gear position and a negative decision (No) is made at step S7, the control device 8 initially terminates the routine without performing any subsequent control action.

[0047] If, on the other hand, the current gear position corresponds to a higher gear position than the calculated gear position and an affirmative decision (Yes) is received at step S7, the control device 8 proceeds to step S8, in which the automatic transmission 4 is downshifted to the calculated gear position. The control device 8 then first terminates the routine of Fig. 2.

[0048] Fig. 7A and Fig. Figure 7B shows illustrations of the operation of the vehicle Ve when the vehicle Ve is moving while being decelerated, in two cases, that is, in the case where the expected vehicle speed is equal to V A is, and in the case where the expected vehicle speed is equal to V B is which is lower than V A is. As in Fig. As shown in 7A, at switching positions (indicated by black circles) correlation lines are drawn according to the expected vehicle speeds V. A or V B A downshift was performed. Fig. 7B indicates the machine speeds at which the Fig. The shift positions shown in 7A are converted. Downshifting is approximated in speed ranges A, B corresponding to the expected vehicle speeds V. A or V B carried out.

[0049] The specific configuration of the control device 8, which performs control during the deceleration drive as described above, is shown in the block diagram of Fig. Figure 8 illustrates this. As an example, the control device 8 consists of an acceleration calculation unit B1, a calculation unit B2 for an expected vehicle speed, a calculation unit B3 for a re-acceleration time acceleration or a re-acceleration time acceleration calculation unit B3, a calculation unit B4 for a realizable acceleration, a target gear position calculation unit B5, and a switching output determination unit B6, as shown in Figure 8. Fig. 8 is shown.

[0050] The acceleration calculation unit B1 calculates the vehicle's acceleration Ve based on data acquired by the output shaft speed sensor 12. The acceleration calculation unit B1 can also calculate the vehicle's acceleration Ve from data acquired by the vehicle speed sensor 13. The calculation unit B2 for expected vehicle speed calculates the expected vehicle speed Vexp based on the acceleration data calculated in the acceleration calculation unit B1 and the data acquired by the vehicle speed sensor 13.The re-acceleration time-acceleration calculation unit B3 calculates the re-acceleration time-acceleration Gexp based on a vehicle speed difference ΔV between the expected vehicle speed Vexp calculated in calculation unit B2 for an expected vehicle speed and the actual vehicle speed Vcur obtained from vehicle speed sensor 13. On the other hand, the calculation unit B4 calculates the achievable acceleration Gabl for each gear position (or gear ratio) of the automatic transmission 4 based on airflow sensor 7.The target gear position calculation unit B5 calculates a target gear position (or a target gear ratio) for the automatic transmission 4 based on the re-acceleration time acceleration Gexp calculated in the re-acceleration time acceleration calculation unit B3 and the achievable acceleration Gabl calculated in the calculation unit B4 for a realizable acceleration. Furthermore, the shift output determination unit B6 performs a determination regarding a shift command to the automatic transmission 4 based on the target gear position calculated in the target gear position calculation unit B5, data from the accelerator pedal position sensor 9, and data from the brake switch 10. Specifically, it determines whether the automatic transmission 4 should be downshifted.

[0051] While the automatic transmission 4 in the example of Fig. 6, Fig. 7A and Fig. If the automatic transmission 4 is a forward eight-speed transmission with eight forward gear positions, this invention can be applied to a continuously variable transmission of the belt type or toroidal type, or an electric continuously variable transmission in a hybrid vehicle. If the automatic transmission 4 is a continuously variable transmission or an electric continuously variable transmission of a hybrid vehicle, as described above, the gear ratio of the automatic transmission 4 that can achieve the "re-acceleration time acceleration" is calculated, and the automatic transmission 4 is controlled based on the calculated gear ratio. For example, as in Fig. As shown in Figure 9A, the transmission ratio γ, which can realize the "re-acceleration time acceleration", is obtained from the "current vehicle speed" and the "expected vehicle speed", and the automatic transmission 4 is controlled based on the transmission ratio γ. The behavior of the engine speed in this case is shown in Fig. 9B shown.

[0052] If the automatic transmission 4 is a continuously variable transmission or an electric continuously variable switching mechanism of a hybrid vehicle, as described above, and the vehicle continues to decelerate after a downshift to increase the speed ratio during deceleration, the engine speed (solid line) can be controlled to reduce it according to the vehicle speed, within a range in which the "re-acceleration time acceleration" can be provided, in particular within a range in which the engine speed does not fall below the speed (dashed line) which provides the re-acceleration time acceleration. Fig. 10 can be provided. In this way, the driver can be given a suitable feeling of deceleration during the deceleration drive.

[0053] When the vehicle Ve is traveling while decelerating based on the "expected vehicle speed" and the "re-acceleration time acceleration" as described above, the machine speed can be controlled such that the range of machine speed used is varied according to the magnitude of the "expected vehicle speed". For example, as in Fig. 11A, Fig. Figure 11B shows the situation when the vehicle is decelerated in two cases, that is, in the case where the expected vehicle speed is equal to V c is, and in the case where the expected vehicle speed is equal to V d is which is lower than V c is, the lowest machine speeds according to these expected vehicle speeds V c , V d each from the in Fig. The characteristic map shown in Figure 11A is obtained. The lowest engine speed in this case corresponds to a lower limit engine speed, which should be ensured to accelerate the vehicle Ve with the "re-acceleration time acceleration" when the vehicle is accelerated after deceleration. Subsequently, as shown in Fig. As shown in 11B, a downshift is performed during deceleration using the lowest engine speed obtained as described above, which is set as the lower limit. While the automatic transmission 4 in the example of Fig. 11B is a forward eight-speed gearbox with eight forward gear positions, the control carried out during deceleration, as in Fig. 11A, Fig. Figure 11B shows how this can be applied to the case where the automatic transmission 4 is a continuously variable transmission or an electric continuously variable transmission of a hybrid vehicle. With the control implemented in this manner, the automatic transmission 4 can downshift with a certain degree of regularity during deceleration, and a good driving feel can be conveyed to the driver at the time of downshifting.

[0054] While the automatic transmission 4 in the example of Fig. 11A, Fig. 11B downshifts during deceleration at the predetermined lowest machine speed set as the lower limit, the maximum machine speed can be set as the upper limit, and the automatic transmission 4 can be controlled such that it downshifts at the maximum machine speed set as the upper limit. For example, as in Fig. 12A and Fig. Figure 12B shows that when the vehicle Ve is decelerated in two cases, that is, in the case where the expected vehicle speed is equal to V c is, and in the case where the expected vehicle speed is equal to V f is which is lower than V e is to determine the maximum machine speeds according to the expected vehicle speeds V e , V f each from the in Fig. The characteristic map shown in Figure 12A is obtained. The maximum engine speed in this case corresponds to the upper limit engine speed, or the upper limit engine speed, within a range of engine speeds that should be ensured to accelerate the vehicle Ve with the "re-acceleration time acceleration" when the vehicle accelerates after deceleration. The maximum or upper limit engine speed is set such that the engine speed does not increase excessively at the time of downshifting during deceleration. As shown in Fig. As shown in Figure 12B, the automatic transmission 4 downshifts during deceleration at the maximum engine speed obtained in this way, which is set as the upper limit. While the automatic transmission 4 in the example of Fig. 12B is a forward eight-speed transmission with eight forward gear positions, the control performed during deceleration, as in Fig. 12A and Fig. 12B shown, applied to the case where the automatic transmission 4 is a continuously variable transmission or an electric continuously variable switching mechanism of a hybrid vehicle, as shown in Fig. 11A and Fig. Control unit shown in 11B.

[0055] In the embodiment described above, the automatic transmission 4 is controlled based on the "expected vehicle speed" and the "current vehicle speed" and the "re-acceleration time acceleration" derived from the "expected vehicle speed" and the "current vehicle speed" such that it downshifts during deceleration. However, the automatic transmission 4 can, for example, be controlled such that it downshifts during deceleration at predetermined intervals of a phase t, as described in Fig. Figure 13 shows the downshifting process. The phase t in this case can be preset according to the driver's driving style. For example, if the driving style is sporty, downshifting occurs at predetermined intervals of phase t, which are shorter than those in the case where the driving style is not sporty. Furthermore, the downshift interval in this case is set within a range of gear positions (gear ratios) that can achieve the "achievable acceleration" obtained based on the "re-acceleration time acceleration," as described above. That is, the gear position (gear ratio) is set within a range in which the vehicle Ve can always accelerate with the "re-acceleration time acceleration" when it accelerates again after downshifting.This control system allows the automatic transmission to downshift with a certain regularity during deceleration. Furthermore, the timing of the downshift can be predicted. Therefore, the driver can be given a good driving feel at the point of downshifting.

[0056] When the automatic transmission 4 downshifts during deceleration, as in each of the embodiments described above, based on the “expected vehicle speed”, the “actual vehicle speed”, and the “reacceleration time acceleration”, a response delay inevitably occurs between the time the “reacceleration time acceleration” is obtained and the time the gear change is actually initiated. If the response delay is large, the timing of actual downshifts will not coincide with the timing of downshifts desired or predicted by the driver, and the driver may experience an odd or unpleasant sensation. Therefore, as described in Fig. Figure 14 shows, for example, that downshifting operations are performed before the normal time using the "predicted vehicle speed" (solid line), which is read out a predetermined time in advance, relative to the "current vehicle speed" (dashed line) obtained from the actual vehicle speed. The "predicted vehicle speed" can be obtained by multiplying the acceleration (especially the deceleration) of the vehicle Ve by a time read out in advance, which is obtained, for example, through an experiment or a simulation. Fig. Figure 14 also shows the current engine speed (dashed line) corresponding to the "current vehicle speed" and the predicted engine speed (solid line) corresponding to the "predicted vehicle speed". Therefore, the control described for each of the above embodiments is performed based on the vehicle speed read in advance in this manner, so that the problem caused by the downshift response delay, as described above, can be eliminated. Consequently, the driving experience of the vehicle Ve can be improved.

[0057] The deceleration of the vehicle Ve, which is used to obtain the aforementioned "predicted vehicle speed," can be calculated from data acquired by the output shaft speed sensor 12 or the vehicle speed sensor 13, as described above. The deceleration can also be obtained from data acquired by an accelerometer installed on the vehicle Ve. The deceleration can also be calculated based on data acquired by a brake pressure sensor provided in a braking system.

[0058] While the correlation line, which indicates the relationship between the "re-acceleration time-acceleration" and the vehicle speed, is shown in the control map described above by Fig. Since the correlation line has the form of a line representing a linear function, it cannot be linear, as in Fig. 15 is given as an example. The line of correlation between the “re-acceleration time-acceleration” and the vehicle speed is not limited to a linear function, as in the embodiments described above, but can, for example, be represented by a quadratic function or an exponential function. In this case, the control of each of the embodiments described above can be achieved using the Fig. The non-linear control map shown in 15 will be performed.

[0059] If the control system uses the control map described above, as in Fig. 5 or Fig. As shown in Figure 15, during the re-acceleration phase, there is indeed an upper limit to the acceleration expected or requested by the driver. If a gear position (gear ratio) is selected that would produce higher acceleration than this upper limit, and the automatic transmission 4 downshifts to this gear position, a lower gear position (or a larger / higher gear ratio) than assumed by the driver will be selected, and the driver may experience a strange or unpleasant sensation. This is reflected in the control map of Fig. 5 or Fig. 15. The “re-acceleration time acceleration”, which is greater than that expected by the driver, is essentially unnecessary. Therefore, the control map of Fig. 5, for example, may be replaced by a control map which is provided with the “expected upper limit acceleration”, as in Fig. 16 shown. Therefore, by setting the upper limit of the acceleration, which is determined with regard to the driver's intention or the expected value, in the control map used to determine the "re-acceleration time acceleration", it is possible to downshift the automatic transmission 4 appropriately, while preventing the gear position (ratio) from being set which would be beyond the driver's assumption, as described above.

[0060] In the flowchart of Fig. 17 is a modified example of the one in the flowchart of Fig. 2 shown the control system, as described above. In the flowchart of Fig. In the control example shown in 17, downshifting is only carried out after it has been determined that the machine speed will fall below a predefined upper limit threshold, so that the machine speed does not increase excessively during the deceleration phase at the time of downshifting. In the flowchart of Fig. 17 is the control content of step S11 and step S12 for the flowchart of Fig. 2 added. Accordingly, in the flowchart of Fig. In the control example shown in Figure 17, the expected vehicle speed Vexp, the re-acceleration time acceleration Gexp, the achievable acceleration Gabl, and the gear position (gear ratio) that can provide the achievable acceleration Gabl are calculated for steps S1 to S5, as in the flowchart of Fig. The control system is shown in step 2. Furthermore, in step S6, it is determined whether the vehicle Ve is moving while being decelerated. If a negative decision (No) is made in step S6, the control device 8 initially terminates this routine without performing any subsequent control actions. Conversely, if the vehicle Ve is moving while being decelerated, and an affirmative decision (Yes) is made in step S6, the control device 8 proceeds to step S7.

[0061] In step S7, it is determined whether the current gear position in the automatic transmission 4 corresponds to a higher gear position than the gear position calculated in the preceding step S5. That is, it is determined whether the gear ratio of the current gear position is lower than the gear ratio of the calculated gear position. If the current gear position corresponds to a lower gear position than the calculated gear position and a negative decision (No) is made in step S7, the control device 8 terminates this routine without performing any further control actions. Conversely, if the current gear position corresponds to a higher gear position than the calculated gear position and an affirmative decision (Yes) is made in step S7, the control device 8 proceeds to step S11.

[0062] In step S11, the engine speed Ne1 is calculated according to the calculated gear position (gear ratio). That is, the engine speed Ne1 is obtained, which is assumed to be reached when the automatic transmission 4 downshifts to the calculated gear position (gear ratio).

[0063] Once the machine speed Ne1 has been calculated in step S11, it is determined whether the machine speed Ne1 is lower than an upper limit threshold (step S12). The upper limit threshold used in this case corresponds to the upper limit of the machine speed, which is determined in such a way that the machine speed does not increase excessively at the time of downshifting during deceleration.

[0064] If the machine speed Ne1 remains greater than or equal to the upper limit threshold and a negative decision (No) is made at step S12, the control device 8 repeats the control of step S12 without proceeding to the next step. That is, the control of step S12 is performed repeatedly until the machine speed Ne1 falls below the upper limit threshold.

[0065] Then, if the machine speed Ne1 falls below the upper limit threshold and a positive decision (Yes) is made at step S12, the control device 8 proceeds to step S8. At step S8, the automatic transmission 4 is downshifted to the calculated gear position (gear ratio). The control device 8 then terminates this routine.

[0066] In the aforementioned manner, the automatic transmission 4 downshifts with regard to the engine speed during deceleration, so that it is less likely or improbable that the driver will perceive a strange or unpleasant sensation in a situation where the engine speed increases excessively at the time of a downshift. Therefore, the driving feel of the vehicle Ve during a downshift during deceleration can be improved.

[0067] In the embodiment described above, the "expected vehicle speed" is derived, for example, from the Fig. The control map shown in Figure 5 is obtained. That is, the "expected vehicle speed" is obtained using the correlation between the "re-acceleration time-acceleration" and the vehicle speed. As described above, the "expected vehicle speed" according to this invention is defined as a target vehicle speed that the driver pursues to be reached when the vehicle accelerates. Based on this definition, it can be assumed that when the vehicle speed reaches the "expected vehicle speed" during an acceleration run, the acceleration becomes zero and the vehicle does not accelerate further. Accordingly, as shown in the time diagram of Fig. Figure 18 shows that the highest vehicle speed Ve reached during a previous acceleration run, before the deceleration run immediately preceding the relevant re-acceleration run begins (that is, the vehicle speed at which the acceleration during the run becomes zero), is set as the "expected vehicle speed". The previous acceleration run represents an acceleration run performed from the time when the "expected vehicle speed" is not set until the time when the deceleration run of this cycle begins.For example, if the control device 8 is configured to clear the “expected vehicle speed” when the ignition switch (or a main switch) is turned off, the preceding acceleration run will correspond to an acceleration run carried out during a phase from the time when the vehicle’s ignition switch Ve was turned on for the current trip to the present time.

[0068] In the flowchart of Fig. Figure 19 shows a control example in which the highest vehicle speed achieved during the previous acceleration run is set as the "expected vehicle speed" described above. In the flowchart described above, Fig. In the basic control shown in step 2, the respective last values ​​of the expected vehicle speed Vexp and the gradient coefficient K at step S3 are maintained if a negative decision (No) is made at step S1. On the other hand, in the drive force control of this control example, the control device 8 can use the flowchart shown in the diagram of Fig. 19. Control shown instead of executing the control of step S3 in the flowchart of Fig. 2. Perform.

[0069] If at step S1 in the flowchart of Fig. If, for example, a negative decision (No) is made in the basic control shown in section 2, the control device 8 proceeds in the flowchart of Fig. 19 proceeds to step S21. In step S21, it is determined whether the vehicle Ve is moving while accelerating. If the vehicle Ve is not accelerating and a negative decision (No) is made in step S21, the control device 8 proceeds to step S22.

[0070] In step S22, the respective last and previous values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained. This control content is similar to that of step S3 in the flowchart of Fig. 2, as described above. That is, if step S1 determines that the vehicle's acceleration run Ve has not finished, or no acceleration run has been performed since the start of the control, the last values ​​of the expected vehicle speed Vexp and the gradient coefficient K correspond to the expected vehicle speed Vexp and the gradient coefficient K that were stored when the ignition switch was turned on for the current run.

[0071] Accordingly, if the control device 8 is configured to clear the expected vehicle speed Vexp and the gradient coefficient K when the ignition switch is turned off, the respective initial values ​​of the expected vehicle speed Vexp and the gradient coefficient K, which were read and stored when the ignition switch was turned on for the current trip, are maintained at step S22. If the control device 8 is configured to store the expected vehicle speed Vexp and the gradient coefficient K at the time the ignition switch is turned off, the expected vehicle speed Vexp and the gradient coefficient K that were stored when the ignition switch was last turned off are continuously maintained.

[0072] If the last values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained at step S22, as described above, the control device 8 proceeds in the flowchart of Fig. Control device 8 proceeds to step S4 and performs a similar control operation to the content described above. If an affirmative decision (Yes) is made at step S21, control device 8 proceeds to step S23.

[0073] In step S23, it is determined whether the current vehicle speed Vcur is higher than the currently set, expected vehicle speed Vexp. If the current vehicle speed Vcur is lower than or equal to the expected vehicle speed Vexp and a negative decision (No) is made in step S23, the control device 8 proceeds to step S22 described above and performs the same control action as described above.

[0074] If, on the other hand, the current vehicle speed Vcur is higher than the expected vehicle speed Vexp and an affirmative decision (Yes) is made at step S23, the control device 8 proceeds to step S24. At step S24, the expected vehicle speed Vexp is updated. In this case, since the current vehicle speed Vcur becomes higher than the expected vehicle speed Vexp, which corresponded to the highest vehicle speed in the previous acceleration run, the current vehicle speed Vcur becomes the new highest vehicle speed. Accordingly, the new highest vehicle speed is set as the last expected vehicle speed Vexp. At step S24, the gradient coefficient K is held at the last value, as described above in step S22.As described above, at step S24, the control device 8 updates the expected vehicle speed Vexp without directly using the correlation or correlation line between the vehicle speed and the acceleration in driving data obtained during the acceleration run. Therefore, the gradient coefficient K, as the slope or gradient of the correlation line, is held at its last value without being updated at step S24.

[0075] Once the expected vehicle speed Vexp is updated at step S24 in the manner described above, the control device 8 proceeds to step S4 in the flowchart of Fig. 2 forward and performs a control according to the content described above, as in the case where the respective last values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained in the preceding step S22.

[0076] In the flowchart of Fig. The control system shown in Figure 19 can, when the control device 8 updates the "expected vehicle speed," obtain the "expected vehicle speed" in a simple manner without performing particularly complex calculations. Therefore, the load on the control device 8 can be reduced. Furthermore, the frequency of updating the "expected vehicle speed" is increased, and the estimation accuracy can be improved, since the possibility of updating the "expected vehicle speed" during acceleration is also provided.

[0077] In the flowchart of Fig. In the basic control described above, as shown in step 2, the expected vehicle speed Vexp and the gradient coefficient K are updated at step S2 based on vehicle driving data Ve, which was stored during the last acceleration run, if the vehicle Ve's acceleration run ends and an affirmative decision (Yes) is made at step S1. On the other hand, the control device 8 can, during the drive force control, which is carried out by the same device as shown in the flowchart of Fig. 20. The control described below is shown instead of performing the control of step S2 in the flowchart of Fig. 2, as described above. That is, during the drive force control carried out by the control device 8, the “expected vehicle speed” can be determined according to a flowchart in the Fig. The control example shown in 20 can be obtained.

[0078] If the acceleration of the vehicle Ve ends and at step S1 at the point shown in the flowchart of Fig. If, according to the basic control shown in step 2, an affirmative decision (yes) is made, the control device 8 proceeds in the flowchart of Fig. 20 to step S31. At step S31, the expected vehicle speed Vexp and the gradient coefficient K are calculated. In the same way as at step S2 of the flowchart of Fig. 2, as described above, the expected vehicle speed Vexp and the gradient coefficient K are calculated and set at step S31 based on driving data (the vehicle speed at the start of the acceleration, the maximum acceleration during the acceleration run, etc.) of the vehicle Ve, which are stored during the acceleration run, the end of which was determined at step S1.

[0079] The expected vehicle speed Vexp calculated in step S31 can be the average of the expected vehicle speeds Vexp set during past multiple re-acceleration runs. For example, the average of the expected speeds Vexp from several re-acceleration runs, including the most recent run, is calculated, and this average is set as the last expected speed Vexp in step S31.

[0080] Once the expected vehicle speed Vexp is set in step S31, it is determined whether the expected vehicle speed Vexp set in this way is higher than the last value of the expected vehicle speed Vexp (step S32). The last value of the expected vehicle speed Vexp corresponds to the last expected vehicle speed Vexp updated in the last cycle of the routine. If the expected vehicle speed Vexp set in step S31 is less than, or equal to, the last value of the expected vehicle speed Vexp, and a negative decision (No) is made in step S32, the control device 8 proceeds to step S33.

[0081] In step S33, the respective last values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained. This control content is similar to that of step S3 in the flowchart of Fig. 2 and this from step S22 in the flowchart of Fig. 19. In this case, the vehicle Ve is in a state where the acceleration run of the vehicle Ve once ended. Therefore, the last values ​​of the expected vehicle speed Vexp and the gradient coefficient K in this case correspond to the expected vehicle speed Vexp and the gradient coefficient K that were calculated and stored when the previous acceleration run ended.

[0082] If, on the other hand, the expected vehicle speed Vexp set in the preceding step S31 is higher than the last value of the expected vehicle speed Vexp, and an affirmative decision (Yes) is made in step S32, the control device 8 proceeds to step S34. In step S34, the expected vehicle speed Vexp and the gradient coefficient K are updated. That is, the expected vehicle speed Vexp and the gradient coefficient K, which are recalculated and set in step S31 of this cycle, are set as the last expected vehicle speed Vexp and gradient coefficient K.

[0083] Once the expected vehicle speed Vexp and the gradient coefficient K are updated at step S34, as described above, the control device 8 proceeds in the flowchart of Fig. Step 2 proceeds to step S4, as in the case where the last values ​​of the expected vehicle speed Vexp and the gradient coefficient K are maintained at the preceding step S33, and this performs a similar control to the content described above. That is, the re-acceleration time acceleration Gexp is calculated based on the last values ​​of the expected vehicle speed Vexp and the gradient coefficient K maintained at step S33, or the last expected vehicle speed Vexp and the gradient coefficient K resulting from the update at step S34.

[0084] As with the expected vehicle speed Vexp described above, the average value of the re-acceleration time accelerations Gexp, which are set during re-acceleration runs that have been performed multiple times in the past, can be used as the re-acceleration time acceleration Gexp calculated in step S4. For example, the average value of the re-acceleration time accelerations Gexp is calculated from several re-acceleration runs, including the most recent run, and the average value is set as the re-acceleration time acceleration Gexp.

[0085] In the flowchart of Fig. With setting 20, the expected vehicle speed Vexp is set, updated at least twice after the acceleration run ends, based on the last expected vehicle speed Vexp and the expected vehicle speed Vexp updated during the last cycle. In another example, the expected vehicle speed Vexp is set based on the average of the expected vehicle speeds Vexp obtained during multiple re-acceleration runs in the past. Then, the re-acceleration time acceleration Gexp is set based on the expected vehicle speed Vexp set in this way.The re-acceleration time acceleration Gexp can also be set based on the average value of the re-acceleration time accelerations Gexp obtained during re-acceleration runs performed multiple times in the past. This allows for adjustments according to the flowchart shown. Fig. The control system shown in Figure 20 suppresses or reduces the influence of errors in driving data used to calculate the "expected vehicle speed" and improves the accuracy in estimating the "expected vehicle speed" and the "re-acceleration time acceleration".

[0086] In the embodiment described above, the “expected vehicle speed” is derived, for example, from the Fig. 4 correlation line shown or the one in Fig. The control map shown in section 5 is obtained. Fig. 4 correlation line shown and the one in Fig. The control maps shown in section 5 are set based on driving data from the previous acceleration run. If the past driving data used in this case were acquired in a simple manner, the amount of data would be enormous. Furthermore, even if the driving environment or driving tendency changes, the driving data obtained before the change would still be used if particular emphasis is placed on past driving data; consequently, the accuracy in estimating the "expected vehicle speed" and the "re-acceleration time-acceleration" could be reduced. Therefore, the control device 8 performs a weighting of the driving data used to obtain the "expected vehicle speed" during the drive force control.

[0087] The weighting of driving data, as described above, is implemented by multiplying past driving data by a predefined weighting coefficient. In another example, weighting is implemented by selecting specific driving data from the entire driving data history and using the selected data to calculate the "expected vehicle speed." For example, weighting of driving data can be achieved by multiplying past driving data, which is used to set the in Fig. 4 correlation line shown or the Fig. The control characteristic map shown in section 5 is used, with a weighting coefficient w (w<1). In another example, the control characteristic map shown in section 5 is used. Fig. The correlation line shown in Figure 4 is set using only the latest or most up-to-date driving data from a given number of trips, counted backwards from the last trip, so that the weighting of the driving data can be carried out.

[0088] As for example in the diagram of Fig. In Figure 21, where a point at which given driving data is displayed in a diagram corresponds to a point (x0, y0) and an approximation line obtained from the course of the driving data is equal to "y=a×x+b", an error d of the point (x0, y0) is expressed as d=(y0-a×x0-b). A quadratic error (w)×d 2 , which is obtained with regard to the weighting coefficient w for weighting, is as (w)×d 2 =(w)×(y0-a×x0-b) 2 Expressed accordingly, the approximation line “y=a×x+b” can be calculated by determining a coefficient a and a coefficient b, which represent the squared error (w)×d. 2minimize, obtain. The coefficient a and the coefficient b, which determine the squared error (w)×d 2 The minimization is calculated according to the recursion formulas given by the following equations (1) and (2). a=∑(w)n+1−k∑(w)n+1−kxkyk−∑(w)n+1−kyk∑(w)n+1−kxk∑(w)n+1−k∑(w)n+1−kxk2−(∑(w)n+1−kxk)2 b=∑(w)n+1−kxk2∑(w)n+1−kyk−∑(w)n+1−kxkyk∑(w)n+1−kxk∑(w)n+1−k∑(w)n+1−kxk2−(∑(w)n+1−kxk)2

[0089] In the foregoing equations (1) and (2), where the term is the sum of x 2 as A n as designated, are A n-1 and A n expressed by recursion formulas, such as the following equations (3) and (4). An−1=∑k=1n−1(w)(n−1)+1−kxk2 An=∑k=1n(w)n+1−kxk2=(w)(An−1+xn2)

[0090] Looking at the term for the sum of x 2 in the recursion formulas of the equations (1) and (2) given above, the current value (A) can ben ) the sum by adding the current value (x n 2 ) of x 2 to the last or previous value (A n-1 The sum can be obtained by multiplying the result of the addition by the weighting coefficient w. This also applies to the terms of other sums in the recursion formulas of equations (1) and (2) given above. Therefore, for the coefficients a and b, which are expressed by equations (1) and (2) above, the current values ​​of the sums can be obtained if the last values ​​of the sums are known. Similarly, even if the history of past driving data is not stored in its entirety, the approximation line “y=a×x+b”, which is weighted by the weighting factor w, can be obtained from the last and current values ​​of the sums if the last values ​​of the sums are stored.

[0091] If the weighting of driving data is carried out, for example, with the weighting coefficient w set to 0.7 (w=0.7), the last data from four acceleration runs make up approximately 75% of the total amount of information, as shown in Fig. 22. Therefore, by weighting the data as described above, the significance of recent data can be increased, and less significant past data can be deleted, for example. If the weighting coefficient w is set to a fixed value, changes per trip in the recursion formulas given above become constant; consequently, the approximation line "y=a×x+b" can be kept simple by calculating the recursion formulas given above. Accordingly, by performing weighting on the trip data as described above, it is possible to reduce the load on the memory storing the data and the load during calculations, while ensuring a certain level of accuracy in estimating the "expected vehicle speed" and the "re-acceleration time-acceleration".

[0092] In the Fig. In the control map shown in Figure 5, as described above, the straight line f used to estimate the "reacceleration time acceleration" from the "expected vehicle speed" is specified by the gradient coefficient K. Therefore, the accuracy in estimating the "reacceleration time acceleration" can be improved by updating the gradient coefficient K through machine learning. For example, as shown in Figure 5, the gradient coefficient K is used to determine the speed of the vehicle. Fig. Figure 23 shows that if the actual acceleration over the vehicle's ground, Ve, is lower than the "reacceleration time acceleration" estimated from the straight line f of the gradient coefficient K, the "expected vehicle speed" is kept constant and the gradient coefficient K is learned so that the actual acceleration over the ground becomes equal to the "reacceleration time acceleration". In the Fig. In the example shown in Figure 23, the gradient coefficient K is modified by learning to a gradient coefficient K' that is smaller than K. If the actual acceleration above the ground is greater than the "reacceleration time acceleration" estimated from the straight line f of the gradient coefficient K, the gradient coefficient K is modified by learning to a larger value. While learning the gradient coefficient K, as described above, can be performed based on data from a previous drive, the learned value of the gradient coefficient K can be obtained with reference to data from multiple drives, so that the "reacceleration time acceleration" can be estimated with improved accuracy.

[0093] In the case where the gradient coefficient K is as described above, in Fig. In the embodiment shown in Figure 23, if the gradient coefficient K is excessively large, the estimated "re-acceleration time acceleration" will be excessively large when there is a large difference between the "expected vehicle speed" and the "actual vehicle speed". Consequently, the lower gear position (or higher gear ratio) than expected by the driver will be selected, and the driver may experience an odd or unpleasant sensation. Therefore, if the gradient coefficient K is learned as described above, an upper limit for the learned value may be provided. For example, as shown in Figure 23, the gradient coefficient K is learned as described above. Fig. As shown in Figure 24, if the actual acceleration over the vehicle's ground, Ve, is greater than the "reacceleration time acceleration" estimated from the straight line f of the gradient coefficient K, the gradient coefficient K is initially increased while the "expected vehicle speed" is kept constant, so that the actual acceleration over the ground becomes equal to the "reacceleration time acceleration". In this case, however, a predetermined gradient coefficient K'' is set as the upper limit.If the actual acceleration above the ground does not match the estimated "reacceleration time acceleration", even if the gradient coefficient K is increased towards the upper limit gradient coefficient K'', the "expected vehicle speed" is changed to a larger value and a straight line f'' is set so that the actual acceleration above the ground becomes equal to the "reacceleration time acceleration".

[0094] Therefore, by performing a learning of the gradient coefficient K with the upper limit set in this way, it is possible to estimate the “reacceleration time acceleration” with high accuracy, while preventing the estimated value of the “reacceleration time acceleration” from being excessively large.

[0095] The control, including the learning of the gradient coefficient K, as described above, is carried out as shown, for example, in the flowchart of Fig. 25 is shown. The flowchart of Fig. The control shown in section 25 is achieved by replacing step S2 in the flowchart of Fig. 2 basic control shown by step S41 in the flowchart of Fig. 25 is provided. That is, in the step S2 described above, the expected vehicle speed Vexp and the gradient coefficient K are updated based on driving data which are stored during the acceleration run, whereas in step S41 a learning of the gradient coefficient K is implemented as described above, and the expected vehicle speed Vexp is obtained based on the learned value of the gradient coefficient K.

[0096] Once the expected vehicle speed Vexp has been updated based on the learned value of the gradient coefficient K, as described above, the control device 8 proceeds to step S4. Then, at step S4 and the subsequent steps, a similar control process is performed as described above.

Claims

[1] Drive force control system for a vehicle (Ve) comprising a machine (3), drive wheels (2) and an automatic transmission (4) which transmits a torque between the machine and the drive wheels, wherein the latter has a control device (8) which is configured such that this (i) controls a propulsive force of the vehicle (Ve) based on a vehicle speed and an amount of accelerator pedal actuation of the vehicle (Ve); (ii) stores an acceleration characteristic which defines a relationship between a re-acceleration time acceleration and the vehicle speed, wherein the re-acceleration time acceleration is used as a control index when the vehicle is moving while it is re-accelerating after a deceleration run, (iii) the re-acceleration time acceleration according to a current vehicle speed based on vehicle driving data (Ve) obtained before the deceleration run and the acceleration characteristic; (iv) a transmission ratio of the automatic transmission (4) which can realize the re-acceleration time acceleration, based on the obtained re-acceleration time acceleration, before the re-acceleration drive is started; (v) estimates, based on the driving data obtained during the acceleration run, a desired, expected vehicle speed to be achieved during the re-acceleration run prior to the deceleration run; and (vi) the re-acceleration time acceleration according to the current vehicle speed is obtained based on the current vehicle speed and the estimated expected vehicle speed,characterized by , that the control device (8) is configured such that this (i) stores a plurality of acceleration characteristic curves on which the re-acceleration time acceleration is determined according to the vehicle speed, (ii) selects one of the acceleration characteristics based on the expected vehicle speed; and (iii) the re-acceleration time acceleration according to the current vehicle speed based on the current vehicle speed, the expected vehicle speed and the selected acceleration characteristic curve. [2] Drive force control system according to claim 1, characterized by , that the control device (8) is configured such that this (i) stores a vehicle speed and acceleration when the re-acceleration run is started, and (ii) the acceleration characteristic curve is updated. [3] Drive force control system according to claim 1 or 2, characterized by , that the control device (8) is configured such that this (i) obtains the re-acceleration time acceleration using an average re-acceleration time acceleration value or an average expected vehicle speed value from re-acceleration runs that have been performed multiple times in the past; and (ii) sets the transmission ratio of the automatic transmission (4) which can achieve the obtained re-acceleration time acceleration. [4] Drive force control system according to one of claims 1 to 3, characterized by, that the control device (8) is configured such that it sets as the expected vehicle speed a maximum vehicle speed recorded by the vehicle (Ve) from a time at which the expected vehicle speed is not set before the deceleration run is started.

Images