Vehicle driving force control device

Abstract

To provide a vehicle drive force control device capable of curbing a reduction in operability of an accelerator pedal while realizing acceleration required by a driver.SOLUTION: A vehicle drive force control device: calculates base acceleration uniquely determined on the basis of an operation amount of an accelerator pedal and a vehicle speed; when demand acceleration is larger than a predetermined value and an operation speed of the accelerator pedal is larger than a predetermined speed (Step S1), sets the demand acceleration to correction acceleration which is larger than the base acceleration; and controls drive force so that the set correction acceleration can be generated (Steps S6 and S7).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a device for controlling driving force in accordance with the amount of depression of an accelerator pedal. [Background technology]

[0002] Patent Document 1 describes a vehicle control device that is configured to correct a target acceleration based on an accelerator operation to satisfy the acceleration required by the driver. Specifically, when the control device described in Patent Document 1 determines that the accelerator pedal has been quickly depressed, it performs a correction to increase the target acceleration by multiplying a target acceleration (reference acceleration) in the case where the accelerator pedal is not quickly depressed by a gain greater than "1". Also, when the accelerator opening becomes small due to an operation such as removing the foot from the accelerator pedal, the target acceleration converges to the reference acceleration according to the accelerator opening and the gain, and when the acceleration becomes "0", the target acceleration completely converges to the reference acceleration. The gain is determined according to the accelerator pedal operation speed, and the relationship between the accelerator pedal operation speed and the amplification gain is mapped in advance and stored in the ECU.

[0003] Patent Document 2 describes a control device that is configured to calculate a target acceleration in accordance with the operation speed of the accelerator pedal, calculate a target vehicle speed based on the target acceleration, and perform driving force control so that the vehicle speed follows the target vehicle speed, thereby compensating for the response delay of the actual vehicle speed to a change in vehicle speed in accordance with accelerator operation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-148342 A [Patent Document 2] JP 2004-276669 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the control device described in the above-mentioned Patent Document 1, when the accelerator pedal is pressed quickly, such as for rapid acceleration, the acceleration required by the driver is realized by performing a correction such as multiplying the reference acceleration by a gain. However, the reference acceleration described in Patent Document 1 is uniquely determined from the accelerator pedal operation amount and the vehicle speed, and when the reference acceleration is multiplied by a gain, there is a risk that the actual required acceleration due to rapid pressing and the corrected acceleration multiplied by the gain may deviate, and as a result, the acceleration required by the driver may not be accurately grasped. In addition, the corrected acceleration is configured to converge to the reference acceleration when the acceleration is "0", in other words, it is configured to return to the reference acceleration when the acceleration is "0". Therefore, in the region near the acceleration "0", a jerk change occurs when the corrected target acceleration is switched to the reference acceleration. Since the region near the acceleration "0" is a steady driving region, the driver operates the accelerator pedal most frequently, and such a jerk change may cause a step (or a step difference) in the acceleration, which may cause the driver to feel strange or uncomfortable. In addition, when the jerk change occurs in the steady driving range where the accelerator pedal is operated frequently, the operability of the accelerator pedal may be deteriorated. Note that such a technical problem also occurs in the Patent Document 2.

[0006] This invention has been made with attention to the above-mentioned technical problems, and aims to provide a vehicle driving force control device that can realize the acceleration desired by the driver while suppressing a decrease in the operability of the accelerator pedal. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a driving force control device for a vehicle, comprising: an accelerator pedal operated by a driver; and a controller that determines a required acceleration based on an amount of operation of the accelerator pedal and a vehicle speed, and outputs a command signal based on the determined required acceleration, the controller comprising: Obtaining a road gradient on which the vehicle is traveling;The accelerator pedal operation amount and the vehicle speed and the road surface gradient The base acceleration is calculated based on the Add the base When the speed is greater than a predetermined value and the accelerator pedal operation speed is greater than the predetermined speed, the required acceleration is set to a corrected acceleration greater than the base acceleration, the corrected acceleration is calculated based on the base acceleration and an amount of acceleration to be added to the base acceleration, and the amount of acceleration to be added is determined by the amount of accelerator pedal operation and the difference between the base acceleration and a dynamic acceleration calculated from the vehicle speed and the accelerator pedal operation speed, and a predetermined control gain.

[0008] In the present invention, the control gain is a maximum gain having a reflection rate of 100% of the difference in the added amount and a minimum gain having a reflection rate of 0% of the difference in the added amount, a range of acceleration to which the maximum gain is applied is set to a low acceleration side in accordance with an increase in vehicle speed, and when the base acceleration is within the range of acceleration to which the maximum gain is applied, the added amount of acceleration is calculated by multiplying the difference by the maximum gain of the control gain. good. Effect of the Invention

[0014] According to the vehicle driving force control device of the present invention, , calculated based on the accelerator pedal operation amount, the vehicle speed, and the road gradient When the required acceleration and the operation speed of the accelerator pedal are greater than a predetermined value, the control for increasing the acceleration is executed. , base addition When the speed is greater than a specified value and the accelerator pedal operation speed is greater than the specified speed Based on the accelerator pedal operation amount, the vehicle speed, and the road gradient The vehicle speed control system is configured to calculate a correction acceleration, which is a final acceleration, by calculating an amount of acceleration to be added to the base acceleration and calculating a correction acceleration, which is a final acceleration. The correction acceleration is calculated based on the base acceleration and an amount of acceleration to be added to the base acceleration, and the amount of acceleration to be added is calculated based on the amount of operation of the accelerator pedal and the difference between the dynamic acceleration calculated from the vehicle speed and the operation speed of the accelerator pedal and the base acceleration. , prescribed regulations The acceleration control gain is determined by the acceleration compensation control gain and the driving force is generated so as to realize the corrected acceleration. This makes it possible to generate the acceleration required by the driver more accurately than, for example, the configuration described in Patent Document 1. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing an outline of a configuration and control system of a vehicle to be controlled by a vehicle control device of the present invention; [Diagram 2] FIG. 4 is a diagram for explaining acceleration characteristics for each accelerator opening degree. [Diagram 3] 4 is a flowchart illustrating an example of control in the embodiment of the present invention. [Figure 4] 10 is a diagram for explaining a method for determining a control amount reflection rate (control gain). FIG. [Diagram 5] 11 is a diagram for explaining how to determine a return G and a control start G. FIG. [Figure 6] FIG. 4 is a diagram showing an example of a time chart when the control example of FIG. 3 is executed, and is particularly a diagram for explaining an example when accelerating with the accelerator opening degree kept constant. [Figure 7] 7 is a diagram for explaining a change in a control amount reflection rate when the control of FIG. 6 is executed. FIG. [Figure 8] 7 is a diagram for explaining acceleration characteristics when the control of FIG. 6 is executed. FIG. [Figure 9] FIG. 13 is a diagram for explaining the effect of the embodiment of the present invention. [Figure 10] 10A to 10C are diagrams for explaining other effects in the embodiment of the present invention. [Figure 11] FIG. 4 is a diagram showing an example of a time chart when the control example of FIG. 3 is executed, and is particularly a diagram for explaining an example when the accelerator opening degree is reduced after acceleration. [Figure 12] 12 is a diagram for explaining a change in a control amount reflection rate when the control of FIG. 11 is executed. FIG. [Figure 13] 12 is a diagram for explaining acceleration characteristics when the control of FIG. 11 is executed. FIG. [Figure 14] FIG. 4 is a diagram showing an example of a time chart when the control example of FIG. 3 is executed, and is particularly intended to explain an example of a case where the accelerator pedal is depressed further again to accelerate after control for increasing acceleration by reducing the accelerator opening degree after acceleration is terminated. [Figure 15] 15 is a diagram for explaining a change in a control amount reflection rate when the control of FIG. 14 is executed. FIG. [Figure 16] 15 is a diagram for explaining acceleration characteristics when the control of FIG. 14 is executed. FIG. [Figure 17] FIG. 4 is a diagram showing an example of a time chart when the control example of FIG. 3 is executed, and in particular is a diagram for explaining an example of a case where the accelerator pedal is depressed further again to accelerate while control is being executed to increase acceleration while releasing the accelerator pedal. [Figure 18] 18 is a diagram for explaining a change in a control amount reflection rate when the control of FIG. 17 is executed. FIG. [Figure 19] 18 is a diagram for explaining acceleration characteristics when the control of FIG. 17 is executed. FIG. [Figure 20] 10 is a flowchart illustrating another control example in the embodiment of the present invention. [Figure 21] 21 is a diagram for explaining an example of a time chart when the control example of FIG. 20 is executed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings. Note that the following embodiment is merely an example of a specific embodiment of the present invention, and is not intended to limit the present invention.

[0018] The vehicle that can be the subject of this invention is a vehicle equipped with an engine or a motor as a driving force source, and may be an electric vehicle equipped with only a motor as a driving force source, or a hybrid vehicle equipped with an engine and a motor as a driving force source. Note that electric vehicles include pure electric vehicles (BEVs) equipped with only a motor as a driving force source, and so-called range extender EVs equipped with an engine exclusively for power generation. Furthermore, they may be so-called plug-in type vehicles or fuel cell vehicles.

[0019] An example of a drive system and a control system of a vehicle Ve to be controlled in an embodiment of the present invention is shown in Fig. 1. The vehicle Ve shown in Fig. 1 includes, as its main components, a drive power source (PWR) 1, front wheels 2, rear wheels 3, an accelerator pedal 4, a brake pedal 5, a detector 6, and an ECU 7.

[0020] The driving force source 1 is a power source that outputs a driving torque for generating a driving force for the vehicle Ve. The driving force source 1 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine, and is configured so that the adjustment of the output and the operating state such as starting and stopping are electrically controlled. In the case of a gasoline engine, the opening degree of the throttle valve, the supply amount or injection amount of fuel, the execution and stopping of ignition, and the ignition timing are electrically controlled. Alternatively, in the case of a diesel engine, the injection amount of fuel, the injection timing of fuel, or the opening degree of the throttle valve in an EGR [Exhaust Gas Recirculation] system are electrically controlled.

[0021] Further, the driving force source 1 in the embodiment of the present invention may be, for example, a motor such as a permanent magnet synchronous motor or an induction motor. In this case, the motor has both a function as an electric motor that is driven by power supply to output motor torque, and a function as a generator that generates electricity by receiving torque from an outside and being driven. That is, the motor is a motor with a power generating function (so-called a motor generator), and switching between the function as an electric motor and the function as a generator is electrically controlled. A battery (both not shown) is connected to the motor via an inverter. Therefore, the motor can be driven as a generator, and the electricity generated at that time can be stored in the battery. Also, electricity stored in the battery can be supplied to the motor, and the motor can be driven as an electric motor to output motor torque.

[0022] Vehicle Ve generates driving force by transmitting driving torque output by driving force source 1 to driving wheels. FIG. 1 shows the configuration of a front-wheel drive vehicle in which front wheels 2 are the driving wheels. Note that vehicle Ve in the embodiment of the present invention may be a rear-wheel drive vehicle in which rear wheels 3 are the driving wheels. Alternatively, vehicle Ve may be a four-wheel (all-wheel) drive vehicle in which both front wheels 2 and rear wheels 3 are driving wheels. Furthermore, when an engine is mounted as driving force source 1, a transmission (not shown) may be provided on the output side of the engine, and the driving torque output by driving force source 1 may be configured to be transmitted to the driving wheels via the transmission.

[0023] The vehicle Ve is also provided with an accelerator pedal 4 that allows the driver to adjust the driving force to accelerate the vehicle Ve. The accelerator pedal 4 is a conventionally known general configuration, and when the driver depresses and releases the accelerator pedal 4, the driving torque output by the driving force source 1 increases in accordance with the amount of operation of the accelerator pedal 4 (amount of depression, or accelerator opening or accelerator pedal position), and the driving force of the vehicle Ve increases. Conversely, when the accelerator pedal 4 is released (the accelerator is released or the accelerator opening or accelerator pedal position is reduced), the driving torque decreases in accordance with the amount of operation of the accelerator pedal 4, and the driving force of the vehicle Ve decreases. At the same time, when a motor is installed as the driving force source 1, the motor functions as a so-called regenerative brake, that is, the regenerative torque output by the motor generates a braking force on the vehicle Ve. Alternatively, when an engine is installed as the driving force source 1, when the accelerator is released, a so-called engine brake is applied, and the braking force of the vehicle Ve increases. For example, engine friction torque and pumping loss act as a resistance force (braking torque) against the drive torque, generating a braking force on the vehicle Ve.

[0024] The vehicle Ve is also provided with a brake pedal 5 that allows the driver to adjust the braking force to brake the vehicle Ve. When the brake pedal 5 is depressed, a braking device such as a hydraulic disk brake or drum brake is activated, generating a braking force for the vehicle Ve. The accelerator pedal 4 may be an operating device that allows the vehicle to travel in a so-called one-pedal mode, in which both acceleration and deceleration are controlled according to the amount of pedal operation by the driver. In this case, the accelerator pedal 4 and the brake pedal 5 may be configured to be controlled in conjunction with each other.

[0025] The detection unit 6 acquires various data for controlling each part of the vehicle Ve, and in particular detects various data related to the operation state of the accelerator pedal 4. The detection unit 6 is a collective term for sensors and devices for detecting such various data. Therefore, the detection unit 6 in the embodiment of the present invention has at least an accelerator position sensor 6a for detecting the operation amount of the accelerator pedal 4 (i.e., the accelerator pedal position or the accelerator opening). The detection unit 6 also has a brake stroke sensor 6b for detecting the operation amount of the brake pedal 5 (i.e., the brake pedal stroke or the brake pedal opening), a vehicle speed sensor 6c for detecting the vehicle speed, an acceleration sensor 6d for detecting the acceleration in the front-rear direction of the vehicle Ve, a gradient angle sensor 6e for detecting the gradient angle of the road surface, and a rotation speed sensor 6f for detecting the rotation speed of the output shaft of the motor or the rotation speed of the output shaft of the engine. The detection unit 6 is electrically connected to the ECU 7, and outputs an electric signal corresponding to the detection value of the above-mentioned various sensors and devices to the ECU 7 as detection data.

[0026] The ECU 7 corresponds to the "controller" in the embodiment of the present invention, and is an electronic control device mainly composed of, for example, a microcomputer, to which various data detected or calculated by the above-mentioned detection unit 6 is input. The ECU 7 also performs calculations using the above-mentioned various input data, as well as pre-stored data, calculation formulas, etc. At the same time, the ECU 7 is configured to output the calculation results as a control command signal to control the vehicle Ve.

[0027] Specifically, for example, data related to the operation state of the accelerator pedal 4 detected by the accelerator position sensor 6a is acquired, and a target driving torque of the driving force source 1 and a target acceleration (or target deceleration) of the vehicle Ve are calculated based on the acquired data. Then, based on the calculated target driving torque, the output of the driving force source 1 is controlled. That is, a control command signal for controlling the driving force source 1 is output. Also, based on the calculated or detected target acceleration or required acceleration, the driving force and braking force generated in the vehicle Ve are controlled in accordance with the operation state of the accelerator pedal 4 or the brake pedal 5. That is, a control command signal for controlling the driving force and braking force is output. Note that, although an example in which one ECU 7 is provided is shown in FIG. 1, a plurality of ECUs 7 may be provided, for example, for each device or equipment to be controlled, or for each control content.

[0028] The vehicle Ve configured as above generally determines a target acceleration of the vehicle Ve according to the amount of operation of the accelerator pedal 4 (accelerator opening) by the driver, and generates a driving force by controlling the torque of the driving force source 1 so as to achieve the target acceleration. This target acceleration is stored in the ECU 7, for example, by mapping it in advance in relation to the vehicle speed as shown in FIG. 2. On the other hand, when the acceleration request is large, such as when the driver depresses the accelerator pedal 4 at a speed equal to or greater than a predetermined speed during rapid acceleration, the acceleration requested by the driver may not be generated due to an unavoidable delay. Therefore, in the embodiment of the present invention, when a relatively large acceleration request is received, an additional amount of the target acceleration is calculated according to the accelerator operation by the driver, and the driving force is controlled so as to generate a corrected target acceleration by adding the additional amount.

[0029] FIG. 3 is a flow chart showing an example of the control. First, it is determined whether or not there is an intention to accelerate (step S1). Specifically, it is determined whether or not the driver's required acceleration G is greater than a predetermined value α and whether or not the operation speed of the accelerator pedal 4 is greater than a predetermined speed β. The determination of whether or not the required acceleration G is greater than the predetermined value α is obtained from a map (FIG. 2) based on the accelerator opening and the vehicle speed. Note that the required acceleration G in this step S1 can be calculated from a predetermined map or the like as described above, so in other words, it is a static acceleration. This static required acceleration corresponds to the "base acceleration Gb" in the embodiment of the present invention. Therefore, if the determination in this step S1 is negative, that is, if the required acceleration G is equal to or less than the predetermined value α or if the operation speed of the accelerator pedal 4 is equal to or less than the predetermined speed β, it is determined that there is no intention to request acceleration, and the control example shown in FIG. 3 is temporarily terminated without executing the subsequent control.

[0030] On the other hand, if the answer to this question in step S1 is affirmative, that is, if the required acceleration G is greater than a predetermined value α and the operating speed of the accelerator pedal 4 is greater than a predetermined speed β, it is determined that there is an intention to request acceleration, and an acceleration characteristic Gi is calculated to realize an acceleration feeling that is in line with the driver's intention (step S2). This acceleration characteristic Gi is a dynamic acceleration in contrast to the static acceleration in the above-mentioned step S1. The required acceleration G in the above-mentioned step S1 is uniquely determined from the accelerator opening and the vehicle speed, whereas the acceleration characteristic Gi is calculated using the operating speed of the accelerator pedal 4 as a parameter in addition to the accelerator opening and the vehicle speed. In other words, by adding the operating speed of the accelerator pedal 4, which is a dynamic operation, as a parameter, the driver's intention to accelerate is grasped more accurately.

[0031] Next, upper limit processing and lower limit processing are performed on the acceleration characteristic Gi calculated in step S2 (step S3). As described above, in order to accurately grasp the driver's intention to accelerate, if the acceleration characteristic Gi is calculated but exceeds the maximum acceleration Gmax that can be achieved by the vehicle Ve, upper limit processing (correction processing) must be performed. Specifically, if the acceleration characteristic Gi exceeds the maximum acceleration Gmax of the vehicle Ve, the acceleration characteristic Gi is corrected to the maximum acceleration Gmax. On the other hand, if the acceleration characteristic Gi is equal to or less than the maximum acceleration Gmax, no correction is made and the value is maintained as it is. The lower limit processing is performed using the base acceleration Gb calculated in step S1.

[0032] Next, the difference Gs (=Gi-Gb) between the base acceleration Gb and the acceleration characteristic Gi is calculated (step S4). The difference Gs is also multiplied by a control gain (hereinafter, also simply referred to as gain) to calculate an acceleration addition amount Gsgain (=Gs×gain) (step S5). These steps S4 and S5 are steps for multiplying the difference Gs between the acceleration characteristic Gi to be realized and the base acceleration Gb by a gain which is a reflection rate of the control amount to obtain a final addition amount Gsgain. That is, step S4 simply obtains the difference, and step S5 obtains the magnitude of the acceleration to be added to the base acceleration Gb. The gain which is a reflection rate of the control amount is obtained from a predetermined map, and a specific method for obtaining the gain will be described later.

[0033] Next, the acceleration addition amount Gsgain calculated in step S5 is added to the base acceleration Gb to calculate the corrected acceleration Gh (step S6). That is, this corrected acceleration Gh becomes the final acceleration required by the driver. This is expressed by the following formula. Gh = Gb + Gsgain

[0034] Next, the corrected acceleration Gh calculated in step S6 is converted into a driving force based on the vehicle weight, gear ratio, tire diameter, running resistance, and other specifications of the vehicle Ve, and is generated as a required driving force (step S7). In other words, the driving force is determined to generate the finally calculated required acceleration.

[0035] Then, it is determined whether the gain has become "0" (step S8), and if it is determined that the gain has become "0", the control example shown in Fig. 3 is terminated. In other words, if the gain becomes "0", the control for increasing the acceleration is terminated and the acceleration returns to the base acceleration Gb. On the other hand, if it is determined that the gain is not "0", the process returns to step S2, and steps S2 to S8 are repeatedly executed until an affirmative determination is made in step S8.

[0036] Here, a method of determining the control gain, which is the reflection rate of the control amount, will be described. The control gain is 0 to 100%, and changes according to the required acceleration. As shown in FIG. 4, the reflection rate of the control amount of 0% is point A (hereinafter also referred to as return G) where the acceleration returns to the base acceleration Gb, in other words, the point where the driver's intention to accelerate disappears. The control amount reflection rate of 100% is point B (hereinafter also referred to as control start G) where the execution of control to improve the acceleration feeling starts, in other words, the point where it is determined that the driver has the intention to accelerate. The control amount reflection rate=0% corresponds to the "minimum gain" in the embodiment of this invention, and the control amount reflection rate=100% corresponds to the "maximum gain" in the embodiment of this invention. The return G is set to be larger than 0G because the vicinity of 0G is a steady running region where the acceleration is "0", and this is the region where the accelerator pedal 4 is used most frequently, and therefore it is desirable for the operability (controllability of the accelerator pedal 4) to be good. Therefore, the control for increasing the acceleration is terminated and the acceleration is increased to greater than 0G when returning to the base acceleration Gb, thereby improving the operability of the accelerator pedal 4 when returning to the base acceleration Gb.

[0037] Point A, which is the return G, and point B, which is the control start G, are determined by the relationship between the required acceleration and the vehicle speed, as shown in FIG. 5, and the return G line increases gradually as the vehicle speed increases. This is because the region of acceleration change felt by the driver becomes larger as the vehicle speed increases. On the other hand, the control start G line decreases as the vehicle speed increases. This is because the driver does not require an increase in acceleration at high vehicle speeds compared to low vehicle speeds. The region below the return G is a region where the control amount reflection rate is 0%, the region above the control start G is a region where the control amount reflection rate is 100%, and the region between the return G and the control start G is a region where the control amount reflection rate is 0 to 100%.

[0038] Next, changes in the required acceleration and the like when the control example of Fig. 3 is executed will be described with reference to a time chart. Fig. 6 shows the time chart, and shows changes in the accelerator opening, the required driving force, the control amount reflection rate (gain), and the G addition execution flag. Note that the time chart shown in Fig. 6 shows an example of a state in which the accelerator opening is constant and acceleration is occurring.

[0039] Specifically, first, the accelerator opening increases, and the required acceleration increases (time t0). As explained in step S1 above, the required acceleration is greater than a predetermined value α, and the operation speed of the accelerator pedal 4 is greater than a predetermined speed β, so control to improve the acceleration is executed. Therefore, the G addition execution flag is turned ON. And, by turning ON the G addition execution flag, the control amount reflection rate becomes 100%. In the required acceleration, the dashed line indicates the base acceleration Gb, and the solid line indicates the corrected acceleration Gh, which is the final acceleration.

[0040] Next, from time t0 to time t1, the base acceleration Gb decreases, and when the base acceleration Gb falls below the line of symbol B, which is the control start G, the control amount reflection rate starts to decrease (time t1). In other words, the control amount reflection rate starts to decrease from 100%, and the acceleration addition amount Gsgain starts to decrease.

[0041] Then, when the base acceleration Gb further decreases and reaches the line A, which is the return G, the control amount reflection rate becomes 0%. That is, the acceleration addition amount Gsgain becomes "0" (time t2). Then, as the control amount reflection rate becomes "0", the G addition execution flag turns OFF. As can be seen from FIG. 6, the control amount reflection rate is configured to become 0% when returning to the base acceleration Gb. That is, when returning to the base acceleration Gb, the acceleration addition amount is configured to converge to "0", in other words, when returning to the base acceleration Gb, no step in acceleration occurs.

[0042] Then, when the control amount reflection rate becomes "0", the acceleration returns to the base acceleration Gb, and the required acceleration further decreases, the required acceleration approaches 0G, which is the steady driving region, but the acceleration near 0G has already returned to the base acceleration Gb, and there is no jerk change in the acceleration. In other words, in this embodiment of the present invention, the return G is greater than 0G, which improves the operability of the accelerator pedal 4.

[0043] FIG. 7 shows the change in the control amount reflection rate in the time chart of FIG. 6, where the control amount reflection rate starts to decrease from 100% at time t1 as indicated by the arrow, and reaches 0% at time t2. FIG. 8 shows the change in the required acceleration G in the time chart of FIG. 6 in relation to the vehicle speed, where the accelerator opening increases at time t0, the required acceleration increases, and control to increase the acceleration is started. Then, as the vehicle speed increases, the required acceleration gradually decreases, and the base acceleration Gb crosses the line indicated by symbol B, which is the control start G, and the required acceleration reaches the line indicated by symbol A, which is the return G, and the control to increase the acceleration ends. At this time, the required acceleration reaches the return G at a point greater than 0G.

[0044] Next, the operation of the embodiment of the present invention will be described. As described above, the embodiment of the present invention is configured to execute control to improve acceleration when the required acceleration is large. Specifically, when the required acceleration is larger than a predetermined value α and the operation speed of the accelerator pedal 4 is larger than a predetermined speed β, an addition amount Gsgain, which is an acceleration to be added to a predetermined base acceleration Gb, is calculated to calculate a corrected acceleration Gh, which is a final acceleration. Then, a driving force is generated to realize the corrected acceleration Gh. As a result, it is possible to generate the acceleration required by the driver more accurately than, for example, the configuration described in Patent Document 1 above.

[0045] According to the embodiment of the present invention, the controllability of the accelerator operation in the steady driving region near 0G when the required acceleration is reduced is improved. FIG. 9 is a comparison between the control example (conventional example) of the above-mentioned Patent Document 1 and the embodiment of the present invention. In the conventional example, the acceleration is near 0G when the control for improving the acceleration is ended and the acceleration returns to the base acceleration Gb, and the time rate of change of the acceleration (jerk) in the vicinity of 0G changes. Therefore, the operability of the accelerator pedal 4 is reduced. This vicinity of 0G is the steady driving region, and therefore the region in which the driver operates the accelerator pedal 4 most frequently. Therefore, it is desired to suppress the jerk change in the vicinity of 0G. In contrast, in the embodiment of the present invention, the required acceleration G is greater than 0G when the control for improving the acceleration is ended and the acceleration returns to the base acceleration Gb. Then, a jerk change occurs in the acceleration region greater than 0G, and when the required acceleration reaches the vicinity of 0G, no jerk change occurs. Therefore, in the embodiment of the present invention, the operability of the accelerator pedal 4 in the steady driving region is good.

[0046] Also, as shown in FIG. 10, in the embodiment of the present invention, the additional amount Gsgain is calculated based on the difference Gs between the acceleration characteristic Gi and the base acceleration Gb, so that the acceleration and driving force to be realized can be appropriately generated. For example, as shown in FIG. 10, in the conventional example, after the acceleration increases, the acceleration suddenly drops, which causes the driver to feel uncomfortable due to the sudden stall. In contrast, in the embodiment of the present invention, the acceleration is configured to maintain the acceleration feeling even after it increases. Therefore, the drop in the latter half of the acceleration can be suppressed, and as a result, the acceleration according to the driver's intention can be generated. In other words, in the embodiment of the present invention, the acceleration additional amount Gsgain can be freely controlled according to the driver's intention, so that the targeted driving force and acceleration can be generated.

[0047] In this way, in the embodiment of the present invention, since the acceleration addition amount Gsgain can be controlled according to the accelerator operation by the driver, the control of Fig. 3 can be applied to a plurality of driving situations, not limited to the example of the state in which the accelerator opening is constant and the vehicle is accelerating as shown in Fig. 6. Below, examples of application to a plurality of driving situations will be described using time charts.

[0048] Fig. 11 is a diagram showing an example of the time chart, showing the change in each parameter such as the required acceleration when the driver releases the accelerator pedal 4 after acceleration. Note that the change in each parameter from time t0 to time t2 is almost the same as the example in Fig. 6, so the same parts will be explained in a simplified manner.

[0049] First, the accelerator opening increases, the required acceleration increases, and the G addition execution flag is turned ON, so that control for increasing the acceleration is executed (time t0). In addition, the control for increasing the acceleration is executed, so that the control amount reflection rate becomes 100%.

[0050] Next, from time t0 to time t1, the base acceleration Gb decreases, and when the base acceleration Gb falls below the line of symbol B, which is the control start G, the control amount reflection rate starts to decrease (time t1). In other words, the control amount reflection rate starts to decrease from 100%, and the acceleration addition amount Gsgain starts to decrease. Also, at time t1, the accelerator opening starts to decrease, and the rate of decrease of the required acceleration G also becomes larger.

[0051] Then, when the accelerator opening and base acceleration Gb further decrease and reach the line A, which is the return G, the control amount reflection rate becomes 0%. In other words, the acceleration addition amount Gsgain becomes "0" (time t2). As the control amount reflection rate becomes "0", the G addition execution flag turns OFF. Note that at this time t2, the required acceleration returns to the base acceleration Gb so that no change in acceleration (a step in acceleration) occurs, and the return G is greater than 0G.

[0052] Next, when the control amount reflection rate becomes "0", the acceleration returns to the base acceleration Gb, and the required acceleration further decreases, the required acceleration approaches 0G, which is the steady driving region, but the acceleration near 0G has already returned to the base acceleration Gb, and there is no jerk change in the acceleration (from time t2 to time t3). In other words, the return G is greater than 0G, which improves the operability of the accelerator pedal 4.

[0053] Then, when the accelerator opening degree is further decreased to near "0" (time t3), the required acceleration becomes negative, which means that the vehicle Ve will start braking.

[0054] FIG. 12 shows the change in the control amount reflection rate in the time chart of FIG. 11, where the control amount reflection rate starts to decrease from 100% at time t1 as shown by the arrow, reaches 0% at time t2, and remains at 0% at time t3. FIG. 13 shows the change in the required acceleration G in the time chart of FIG. 11 in relation to the vehicle speed, where the accelerator opening increases at time t0, the required acceleration increases, and control to improve the acceleration is started. Then, as the vehicle speed increases, the required acceleration gradually decreases, and the base acceleration Gb crosses the line of symbol B, which is the control start G. When the accelerator pedal is further released and the accelerator opening decreases, the required acceleration G decreases according to the change in the accelerator opening, and the reduced required acceleration G crosses the line of symbol A, which is the return G, and becomes negative. When the required acceleration G reaches the return G, the control to improve the acceleration ends.

[0055] Next, referring to a time chart, changes in each parameter when the control example of FIG. 3 is applied to the case where the accelerator pedal 4 is depressed further again to accelerate after control for increasing acceleration by releasing the accelerator pedal 4 is terminated will be described. Note that the changes in each parameter will be described by omitting or simplifying parts similar to those in FIG. 6 and FIG. 11 described above. FIG. 14 is a diagram showing the time chart, and first, from time t0 to time t2, it is similar to the example of the time chart of FIG. 11, that is, control is executed to increase acceleration in accordance with an increase in the accelerator opening, and then the accelerator opening and base acceleration Gb decrease, so that the required acceleration G returns to the base acceleration Gb (from time t0 to time t2). Then, the accelerator opening decreases further, and the required acceleration G becomes a negative value (time t3).

[0056] When the accelerator pedal 4 is depressed again from that state, the required acceleration G increases (from time t3 to time t4). The required acceleration from time t3 to time t4 is set to the base acceleration Gb. If the accelerator pedal 4 is subsequently depressed further and crosses the line B at which control starts, control to increase the acceleration is executed again.

[0057] FIG. 15 shows the change in the control amount reflection rate in the time chart of FIG. 14, where the control amount reflection rate starts to decrease from 100% at time t1 as shown by the arrow, reaches 0% at time t2, and remains at 0% at time t3 because the acceleration is negative, and at time t4, the required acceleration G increases but does not reach the line B at which control starts. FIG. 16 shows the change in the required acceleration G in the time chart of FIG. 14 in relation to the vehicle speed, where the accelerator opening increases at time t0, the required acceleration increases, and control to increase the acceleration starts. Then, as the vehicle speed increases, the required acceleration gradually decreases, and the base acceleration Gb crosses the line B, which is the control start G. When the accelerator pedal is released and the accelerator opening decreases, the required acceleration G decreases in accordance with the change in the accelerator opening, and the reduced required acceleration G crosses the line A, which is the return G, and the control to increase the acceleration ends. Thereafter, the accelerator opening degree is further decreased and the required acceleration G becomes negative, but when the accelerator pedal is depressed further again, the required acceleration G reaches the return G.

[0058] Next, referring to a time chart, changes in each parameter when the control example in Fig. 3 is applied to the case where the accelerator pedal 4 is depressed again to accelerate while the control amount reflection rate is decreasing due to the release of the accelerator pedal 4 will be described. Note that the same parts of the changes in each parameter as those in the time charts in Figs. 6, 11, and 14 described above will be omitted or simplified. Fig. 17 shows the time chart, and first, control is executed to improve acceleration in accordance with an increase in the accelerator opening (from time t0 to time t1).

[0059] Next, the base acceleration Gb falls below the line B, which is the start of control, so that the control amount reflection rate drops from 100% and is controlled to be between 0 and 100% (time t2). Therefore, at time t2, the acceleration addition amount Gsgain drops, and the difference Gs from the above-mentioned base acceleration Gb becomes smaller.

[0060] Next, when the accelerator pedal 4 is depressed again from this state, the accelerator opening increases, and the required acceleration G also increases accordingly (from time t2 to time t3). When the required acceleration crosses line B, which is the control start point, the control amount reflection rate becomes 100% again (time t3). Note that while the control of FIG. 17 is being executed, since the G addition execution flag was turned ON at time t0, the required acceleration G has not returned to the base acceleration Gb, and the flag remains ON.

[0061] FIG. 18 shows the change in the control amount reflection rate in the time chart of FIG. 17, where the control amount reflection rate starts to decrease from 100% at time t1 as indicated by the arrow, decreases to near 0% at time t2, and reaches 100% again at time t3 when the accelerator pedal 4 is depressed further. FIG. 19 shows the change in the required acceleration G in the time chart of FIG. 17 in relation to the vehicle speed, where the accelerator opening increases at time t0, the required acceleration increases, and control to increase the acceleration is started. Then, as the vehicle speed increases, the required acceleration gradually decreases, and at time t1, the base acceleration Gb crosses the line of symbol B, which is the control start G. When the accelerator pedal is released and the accelerator opening decreases, the required acceleration G decreases in response to the change in the accelerator opening (at time t2). From that state, the accelerator pedal is depressed further again, and the line of symbol B, which is the control start, is crossed again (at time t3).

[0062] Next, another control example in the embodiment of the present invention will be described. In the control example of FIG. 3 described above, the system is configured to determine whether or not there is an intention to accelerate using the required driving force calculated from the accelerator opening and the vehicle speed, and the operation speed of the accelerator pedal 4 as parameters, and to execute control to improve the acceleration. On the other hand, when the road surface on which the vehicle Ve runs is not a flat road but an uphill road with a road surface gradient of a predetermined value or more, it is preferable to generate a driving force taking into consideration the road surface gradient. When a driving force similar to that on a flat road is generated on an uphill road, for example, control to improve the acceleration may be executed even if the driver's intention to accelerate has disappeared. Therefore, in the embodiment of the present invention, the system is configured to detect the road surface gradient in addition to the accelerator opening, the vehicle speed, and the operation speed of the accelerator pedal 4, and to execute control to improve the acceleration.

[0063] Fig. 20 is a flow chart showing an example of the control. Note that the control content of each step is the same as the control content of Fig. 3 described above, except for the control that takes into account the road surface gradient, so the description thereof will be omitted or simplified.

[0064] First, it is determined whether or not there is an intention to accelerate (step S100). This step S100 is almost the same as step S1 in the control example of FIG. 3, and it is determined whether or not the driver's required acceleration G is greater than a predetermined value α and whether or not the operation speed of the accelerator pedal 4 is greater than a predetermined speed β. The determination of whether or not the required acceleration G is greater than the predetermined value α is made using the accelerator opening, the vehicle speed, and the road surface gradient as parameters. Note that the required acceleration G in this step S100 is a static acceleration equivalent to the above-mentioned base acceleration Gb. If the determination in this step S100 is negative, that is, if the required acceleration G is equal to or less than the predetermined value α or if the operation speed of the accelerator pedal 4 is equal to or less than the predetermined speed β, it is determined that there is no intention to accelerate, and the control example shown in FIG. 20 is temporarily terminated without executing the subsequent control.

[0065] On the other hand, if the answer to the question in step S100 is YES, that is, if the required acceleration G is greater than a predetermined value α and the operation speed of the accelerator pedal 4 is greater than a predetermined speed β, it is determined that there is an intention to request acceleration, and an acceleration characteristic Gi for realizing an acceleration feeling according to the driver's intention is calculated (step S200). This step S200 is almost the same as step S2 in the control example of FIG. 3, and this acceleration characteristic Gi is a dynamic acceleration in contrast to the static acceleration in the above-mentioned step S100. The required acceleration G in the above-mentioned step S100 is uniquely determined by the accelerator opening, the vehicle speed, and the road surface gradient, whereas the acceleration characteristic Gi is calculated using the operation speed of the accelerator pedal 4 as a parameter in addition to the accelerator opening, the vehicle speed, and the road surface gradient. In other words, by adding the operation speed of the accelerator pedal 4, which is a dynamic operation, as a parameter, the driver's intention to accelerate is grasped more accurately.

[0066] Next, upper limit processing and lower limit processing are performed on the acceleration characteristic Gi calculated in step S200 (step S300). This is almost the same as step S3 in the control example of FIG. 3, and as described above, in order to accurately grasp the driver's intention to accelerate, if the acceleration characteristic Gi is calculated but exceeds the maximum acceleration Gmax that can be achieved by the vehicle Ve, upper limit processing (correction processing) must be performed. Specifically, if the acceleration characteristic Gi exceeds the maximum acceleration Gmax of the vehicle Ve, the acceleration characteristic Gi is corrected to the maximum acceleration Gmax. On the other hand, if the acceleration characteristic Gi is equal to or less than the maximum acceleration Gmax, the acceleration characteristic Gi is not corrected and the value is maintained as it is. Note that the lower limit processing is the base acceleration Gb calculated in step S1. Also, the maximum acceleration Gmax is calculated based on the vehicle speed and road gradient at an accelerator opening of 100%.

[0067] Next, the difference Gs (=Gi-Gb) between the base acceleration Gb and the acceleration characteristic Gi is calculated (step S400). The difference Gs is multiplied by a gain to calculate an acceleration addition amount Gsgain (=Gs×gain) (step S500). These steps S400 and S500 are similar to steps S4 and S5 in the control example of FIG. 3, so detailed explanations will be omitted.

[0068] Next, the acceleration addition amount Gsgain calculated in step S500 is added to the base acceleration Gb to calculate the corrected acceleration Gh (step S600). This is the same as step S6 in the control example of FIG. 3, that is, this corrected acceleration Gh becomes the final acceleration required by the driver.

[0069] Next, the corrected acceleration Gh calculated in step S600 is converted into a driving force based on the vehicle weight, gear ratio, tire diameter, running resistance, and other specifications of the vehicle Ve, and is generated as a required driving force (step S700). This is the same as step S7 in the control example of Fig. 3, that is, the driving force for generating the finally calculated required acceleration is determined.

[0070] Then, it is determined whether the gain has become "0" (i.e., whether the control amount reflection rate has become 0%) (step S800), and if it is determined that the gain has become "0", the control example shown in Fig. 20 is terminated. This is similar to step S8 in the control example of Fig. 3, that is, if the gain becomes "0", the control for increasing the acceleration is terminated and the acceleration returns to the base acceleration Gb. On the other hand, if it is determined that the gain is not "0", the process returns to step S200, and steps S200 to S800 are repeatedly executed until an affirmative determination is made in step S800.

[0071] In this way, the control example of FIG. 20 is configured to set the required acceleration taking into consideration the road surface gradient. FIG. 21 is a time chart comparing an example of a case where control for improving acceleration is executed without taking into consideration the road surface gradient (conventional example) with an example of a case where control for improving acceleration is executed taking into consideration the road surface gradient. In the conventional example shown on the left side of the page of FIG. 21, the accelerator opening increases at time t10', so that the G addition execution flag is turned ON and control for improving acceleration is started. Next, the road surface gradient starts to increase from 0% at time t11', and the road surface gradient becomes γ% at time t12'. Then, in the transition period from time t12' to time t13', the required acceleration crosses the 0G line at γ% uphill and returns to the base acceleration Gb at time t13'. In other words, even though the intention to accelerate disappears during the transition period between time t12' and time t13', the base acceleration Gb is returned to at time t13', which is in the deceleration region. Therefore, the control does not match the driver's intention to accelerate.

[0072] In contrast, in the embodiment of the present invention shown on the right side of FIG. 21, the accelerator opening increases at time t10, and the G addition execution flag is turned on, and control to increase the acceleration is started. Next, the road gradient starts to increase from 0% at time t11, and becomes γ% at time t12. Then, at time t12 when the road gradient becomes γ%, the acceleration is returned to the base acceleration Gb. That is, when the acceleration of the vehicle Ve becomes 0G on an uphill road, it is determined that the intention to accelerate has disappeared. In other words, for a given amount of operation of the accelerator pedal 4, the region where the acceleration becomes "0" when the amount of operation of the accelerator pedal 4 is present with a road gradient (when the gradient is equal to or greater than the given gradient) is larger than the region where the acceleration becomes "0" when the road gradient is not present (when the gradient is less than the given gradient). In this way, in the embodiment of the present invention, the return to the base acceleration Gb is corrected from the case of a flat road in consideration of the resistance of the road gradient, thereby enabling control according to the driver's intention to accelerate. That is, the driving force can be appropriately controlled according to the driver's intention to accelerate. [Explanation of symbols]

[0073] 1. Driving force source 2 Front wheels 3 Rear wheel 4. Accelerator pedal 5. Brake pedal 6. Detection section 7 ECU (Electronic Control Unit) Vehicle

Claims

1. A driving force control device for a vehicle, comprising: an accelerator pedal operated by a driver; and a controller that determines a required acceleration based on an amount of operation of the accelerator pedal and a vehicle speed, and outputs a command signal based on the determined required acceleration, The controller: Obtaining a road gradient on which the vehicle is traveling; calculating a base acceleration that is uniquely determined based on the accelerator pedal operation amount, the vehicle speed, and the road surface gradient; When the base acceleration is greater than a predetermined value and the operation speed of the accelerator pedal is greater than a predetermined speed, the required acceleration is set to a corrected acceleration that is greater than the base acceleration; the corrected acceleration is calculated based on the base acceleration and an addition amount of acceleration to the base acceleration, The amount of acceleration to be added is determined by a difference between the dynamic acceleration calculated from the accelerator pedal operation amount, the vehicle speed, and the accelerator pedal operation speed, and the base acceleration, and by a predetermined control gain. A driving force control device for a vehicle.

2. 2. The vehicle driving force control device according to claim 1, the control gain has a maximum gain at which a reflection rate of the difference on the added amount is 100% and a minimum gain at which a reflection rate of the difference on the added amount is 0%, The range of acceleration to which the maximum gain is applied is set to a lower acceleration side in response to an increase in vehicle speed, When the base acceleration is within a range of acceleration to which the maximum gain is applied, the additional amount of the acceleration is calculated by multiplying the difference by the maximum gain of the control gain. A driving force control device for a vehicle.

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