vehicle

Abstract

The present invention provides a vehicle capable of limiting the rate of change of driving force adapted to driving conditions through simple calculation processing. The vehicle (1) comprises: a power source (11) for generating power, a required driving force calculation unit (31) for calculating the required driving force based on driving operation, an actual driving force calculation unit (32) for calculating the actual driving force that follows the required driving force by limiting the rate of change, and a drive control unit (35) for driving the power source so as to output the calculated actual driving force. Furthermore, the actual driving force calculation unit (32) changes the rate of change of the actual driving force based on the difference between the required driving force and the actual driving force and the elapsed time during which the rate of change of the actual driving force is limited.

Description

Technical Field

[0001] The present invention relates to a vehicle including an actual driving force calculation unit that limits a rate of change to calculate an actual driving force that follows a required driving force. Background Art

[0002] In vehicles powered by electric motors, such as EVs (Electric Vehicles) and HEVs (Hybrid Electric Vehicles), a control unit typically calculates a required driving force based on driving maneuvers and limits the rate of change to calculate an actual driving force that follows the required driving force. The electric motor is then controlled to generate the calculated actual driving force. Limiting the rate of change of the required driving force mitigates sudden changes in the driving force output from the electric motor, even during abrupt driving maneuvers. Note that this driving force can also be referred to as torque.

[0003] Various methods for limiting the rate of change of the required driving force have been proposed. For example, Patent Document 1 discloses a method for calculating actual torque by limiting the rate of change to below an upper limit when the rate of change of the required torque calculated based on the driving operation exceeds an upper limit.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-072974 Summary of the Invention

[0007] Technical issues

[0008] However, there is room for improvement in conventional methods for limiting the rate of change of driving force. For example, a configuration that uniformly limits the rate of change for sudden changes in the required driving force presents difficulties in adapting the rate of change to the driving conditions. Furthermore, a configuration that employs multiple limiting processes tailored to the driving conditions to mitigate the rate of change of the actual driving force complicates the calculation of the actual driving force.

[0009] An object of the present invention is to provide a vehicle capable of limiting the rate of change of driving force in accordance with driving conditions through simple calculation processing.

[0010] Technical Solution

[0011] The invention according to claim 1 is a vehicle, characterized by comprising:

[0012] a power source, which generates power;

[0013] a requested driving force calculation unit that calculates the requested driving force based on the driving operation;

[0014] an actual driving force calculation unit that limits a rate of change to calculate an actual driving force that follows the required driving force; and

[0015] a drive control unit that drives the power source so as to output the calculated actual driving force,

[0016] The actual driving force calculation unit changes a rate of change of the actual driving force based on a difference between the required driving force and the actual driving force and an elapsed time during which the rate of change of the actual driving force is restricted.

[0017] The invention of solution 2 is characterized in that, in the vehicle of solution 1,

[0018] The larger the difference is and the longer the elapsed time is, the greater the change rate is.

[0019] The actual driving force calculation unit decreases the change rate as the difference is smaller and the elapsed time is shorter.

[0020] The invention of solution 3 is characterized in that, in the vehicle of solution 1 or 2,

[0021] The actual driving force calculation unit resets the elapsed time on the condition that the absolute value of the difference between the required driving force and the actual driving force becomes equal to or smaller than a first threshold value.

[0022] The invention of claim 4 is characterized in that, in the vehicle of any one of claims 1 to 3,

[0023] The actual driving force calculation unit resets the elapsed time when a predetermined driving condition is determined.

[0024] The invention of claim 5 is characterized in that, in the vehicle of claim 4,

[0025] When the actual driving force exceeds zero, the actual driving force calculation unit performs zero-cross control to limit the rate of change of the actual driving force.

[0026] The predetermined driving condition includes the termination of the zero-cross control.

[0027] The invention of claim 6 is characterized in that, in the vehicle of claim 4 or 5,

[0028] The predetermined driving condition includes a case where the driving operation amount of acceleration changes in a stepwise manner from a first operation amount greater than zero to a second operation amount greater than the first operation amount.

[0029] The invention of claim 7 is characterized in that, in the vehicle according to any one of claims 1 to 6,

[0030] The power source is an electric motor,

[0031] Power is transmitted from the electric motor to the drive wheels.

[0032] Technical Effects

[0033] Parameters such as the elapsed time that limits the rate of change of the actual driving force are known to reflect driving conditions well. For example, during near-constant speed driving, the accelerator pedal may be continuously pressed a constant amount, the accelerator pedal's operation fluctuates within a constant amount, or the accelerator pedal is repeatedly pressed and released. In each of these situations, the actual driving force and the required driving force reach equilibrium within a short period of time, so the elapsed time that limits the rate of change does not increase. On the other hand, during acceleration driving, such as when the accelerator pedal is continuously pressed significantly, the required driving force and the actual driving force diverge, and the time it takes for the actual driving force to catch up to the required driving force increases.

[0034] According to the present invention, by varying the rate of change of the actual driving force using the parameters that effectively reflect the driving conditions described above, it is possible to implement a rate of change limit for the actual driving force that reflects the driving conditions. Furthermore, since the actual driving force calculation unit varies the rate of change of the actual driving force based on the parameters described above and the difference between the required driving force and the actual driving force, the actual driving force calculation process can be simplified. Thus, a rate of change limit for the driving force that adapts to the driving conditions can be implemented through a simple calculation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a block diagram showing a vehicle according to the first embodiment of the present invention.

[0036] Figure 2 This is a diagram showing an example of a limit change rate map.

[0037] Figure 3 This is a timing chart showing the first operational example of the vehicle according to the first embodiment.

[0038] Figure 4 This is a timing chart showing a second operation example of the vehicle according to the first embodiment.

[0039] Figure 5 This is a flowchart showing a control process of an actual driving force calculation unit in a vehicle according to the second embodiment of the present invention.

[0040] Figure 6 This is a timing chart showing an example of the operation of the vehicle according to the second embodiment.

[0041] Figure 7 is a timing chart showing a comparative example.

[0042] Figure 8 This is a timing chart showing an example of the operation of the vehicle according to the second embodiment.

[0043] Figure 9 is a timing chart showing a comparative example.

[0044] Explanation of symbols

[0045] 1 vehicle

[0046] 2 drive wheels

[0047] 11 Travel motor

[0048] 20 Driving Operations

[0049] 21 Accelerator pedal

[0050] 22 Brake pedal

[0051] 30 Control Department

[0052] 31 Required driving force calculation unit

[0053] 32 Actual driving force calculation unit

[0054] 33 Limiting rate of change mapping

[0055] 34 elapsed timer

[0056] 35 Drive control unit DETAILED DESCRIPTION

[0057] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0058] (Implementation Method 1)

[0059] Figure 1 This is a block diagram illustrating a vehicle according to an embodiment of the present invention. Vehicle 1 in this embodiment is, for example, an EV, and includes drive wheels 2, a travel motor (electric motor) 11 that generates power for the drive wheels 2, an inverter 12 that drives the travel motor 11, a battery 13 that supplies power to drive the travel motor 11, a driving control unit 20 including an accelerator pedal 21 and a brake pedal 22, and a control unit 30 that receives an operation signal from the driving control unit 20 and controls the drive of the inverter 12.

[0060] The control unit 30 can be composed of a single ECU (Electronic Control Unit) or a plurality of ECUs communicating with each other to operate in coordination. The control unit 30 includes a ROM (Read Only Memory) storing a control program and a CPU (Central Processing Unit) performing calculations. The CPU implements multiple functional modules by executing the control program. The multiple functional modules include a required driving force calculation unit 31 that calculates the required driving force based on the operation signal of the driving operation unit 20, an actual driving force calculation unit 32 that calculates the actual driving force that follows the required driving force by limiting the rate of change (the amount of change per unit time), a limited rate of change map 33 used by the actual driving force calculation unit 32 when calculating the actual driving force, and a drive control unit 35 that controls the drive of the inverter 12 via a timer 34 so that the actual driving force calculated by the actual driving force calculation unit 32 is output from the travel motor 11.

[0061] The required driving force calculation unit 31 calculates the required driving force according to the amount of operation of the accelerator pedal 21 or the brake pedal 22, for example. The required driving force ranges from a positive required driving force when the accelerator pedal 21 is operated to a negative required driving force when the brake pedal is operated. A configuration may also be employed in which acceleration and braking can be achieved solely by operating the accelerator pedal 21. In this case, the required driving force calculation unit 31 calculates the required driving force as zero when the amount of operation of the accelerator pedal 21 is a reference operation amount; and calculates a larger positive required driving force as the operation amount exceeds the reference operation amount; and calculates a smaller negative required driving force as the operation amount is less than the reference operation amount. The required driving force changes rapidly when the driver abruptly operates the driving operation unit 20.

[0062] The actual driving force calculation unit 32 receives the requested driving force from the required driving force calculation unit 31 and calculates an actual driving force that follows the requested driving force. When the difference between the requested driving force and the actual driving force is below a first threshold value and the requested driving force changes at a rate less than a predetermined rate of change, the actual driving force calculation unit 32 does not perform rate of change restriction processing and instead calculates an actual driving force that is substantially consistent with the requested driving force. On the other hand, if the requested driving force changes at a rate greater than the predetermined rate of change, the actual driving force calculation unit 32 begins rate of change restriction processing for the actual driving force and calculates an actual driving force that deviates from the requested driving force. After starting the rate of change restriction processing, if the difference between the requested driving force and the actual driving force again falls below the first threshold value, the actual driving force calculation unit 32 terminates the rate of change restriction processing. The first threshold value can be set to a difference value at which the rate of change restriction processing ends, such as the maximum difference value that allows the requested driving force and the actual driving force to be considered substantially consistent. The first threshold value may be set to different values when the requested driving force is a positive value and when the requested driving force is a negative value, or / and depending on the magnitude of the requested driving force.

[0063] The elapsed timer 34 counts the elapsed time during which the actual driving force calculation unit 32 continues the rate-of-change limiting process. The elapsed timer is reset when the absolute value of the difference between the required driving force and the actual driving force falls below a first threshold. For example, the elapsed timer is reset at the start or end of the rate-of-change limiting process and continues to count the elapsed time since the start of the continuous rate-of-change limiting process. The elapsed timer 34 can be either a software timer or a hardware timer.

[0064] Figure 2 : is a diagram showing an example of a restricted change rate map. In the process of executing the restriction process of the change rate, the actual driving force calculation unit 32 changes the change rate of the actual driving force based on the difference between the required driving force and the actual driving force (hereinafter referred to as "driving force difference") and the elapsed time of the restriction process counted by the elapsed timer 34 (hereinafter referred to as "elapsed time"). The restricted change rate map 33 is map data showing the relationship between them. Figure 2As shown, the rate-of-change limit map 33 is set so that the smaller the absolute value of the driving force difference and the shorter the elapsed time, the smaller the rate of change; and the larger the absolute value of the driving force difference and the longer the elapsed time, the larger the rate of change. Furthermore, the rate-of-change limit map 33 can also be set so that, when focusing on the same row of absolute values of the driving force difference, the longer the elapsed time, the larger the rate of change; and, when focusing on the same column of elapsed time, the larger the absolute value of the driving force difference, the larger the rate of change. Furthermore, the rate-of-change limit map 33 can also be set so that, for the rate of change in the range W1 where the absolute value of the driving force difference is small, the ratio of the change in the rate of change with elapsed time is smaller than for the rate of change in the range where the absolute value of the driving force difference is large. This setting for range W1 allows the rate of change to remain low even when the elapsed time increases when the driving force difference is small.

[0065] During the rate-of-change limitation process, the actual driving force calculation unit 32 determines the rate of change based on, for example, the difference in driving force calculated in the previous control cycle and the elapsed time, while referencing the limited rate-of-change map 33. The actual driving force calculation unit 32 then adds the amount of change in the direction that follows the required driving force, which has the determined rate of change, to the actual driving force calculated in the previous control cycle to calculate the actual driving force for the next control cycle. However, if changing the actual driving force at the determined rate of change would cause the actual driving force to exceed the required driving force, the actual driving force calculation unit 32 may calculate the actual driving force to a value that is substantially consistent with the required driving force.

[0066] The drive control unit 35 receives the actual drive force from the actual drive force calculation unit 32 and controls the inverter 12 so that the actual drive force is output from the travel motor 11 .

[0067] <Action Example 1>

[0068] Figure 3This is a timing diagram illustrating an operational example 1 of the vehicle according to Embodiment 1. Operational example 1 illustrates the operation of vehicle 1 during startup. When vehicle 1 starts, if the accelerator pedal 21 is depressed relatively sharply to accelerate the vehicle, the requested driving force increases rapidly, and the actual driving force calculation unit 32 begins limiting the rate of change (time t1). The elapsed timer 34 counts the elapsed time from time t1, when the limiting process begins. During the initial phase T1 after the limiting process begins, the difference between the requested driving force and the actual driving force is large, while the elapsed time is short. Therefore, the rate of change obtained from the limited rate of change map 33 is small. Therefore, during the initial phase T1 of the limiting process, the actual driving force tracks the requested driving force at a small rate of change. By limiting the rate of change during the initial phase T1, the actual driving force does not increase rapidly from the time the vehicle is stopped (no power is being transmitted to the power transmission mechanism between the travel motor 11 and the drive wheels 2) until the vehicle starts (power transmission begins). This prevents the occurrence of gear rattling and other jostling in the power transmission mechanism.

[0069] During the intermediate period T2 of the rate-of-change limitation process, the driving force difference remains relatively large, and the elapsed time increases. Consequently, the rate of change obtained from the rate-of-change limitation map 33 reaches a large value. Consequently, during the intermediate period T2, the actual driving force approaches the required driving force at a large rate of change. This change in rate of change allows for rapid acceleration in accordance with the driver's intent, tailored to the driving conditions at the start of the vehicle.

[0070] During the final stage T3 of the rate-of-change limitation process, the elapsed time of the limitation process increases while the driving force difference decreases, resulting in a smaller rate of change obtained from the limited rate-of-change map 33. Consequently, during the final stage T3, the actual driving force converges to the required driving force at a small rate of change. In driving conditions during a start, the accelerator pedal 21 is operated to maintain a constant vehicle speed after the start, thus ensuring that the actual driving force remains constant. Therefore, when the actual driving force converges to the required driving force, the travel motor 11 and the power transmission mechanism transition from increasing the driving force to stopping the increase in driving force. Generally, when the temporal variation of the driving force changes dramatically, a collision may occur between the travel motor 11 and the power transmission mechanism. However, by limiting the rate of change during the final stage T3, the increase in the actual driving force is gradually stopped, thus suppressing such a collision.

[0071] Then, the difference between the required driving force and the actual driving force decreases, and the change rate limiting process by the actual driving force calculation unit 32 ends (time t2 ), and the elapsed timer 34 is reset and the timing stops.

[0072] <Action Example 2>

[0073] Figure 4 This is a timing diagram illustrating Example 2 of the vehicle's operation according to Embodiment 1. Example 2 illustrates the operation of vehicle 1 during constant speed driving. During constant speed driving, the driver maintains and depresses the accelerator pedal 21 with a constant amount, as in periods T10 and T12. On the other hand, during period T11, the amount of accelerator pedal 21 depressed may fluctuate, with the driver sometimes releasing and sometimes depressing the accelerator pedal. If such an operation is performed during period T11, the required driving force may intermittently fluctuate in magnitude, causing the actual driving force calculation unit 32 to initiate a rate-of-change restriction process. However, even in such a case, the intermittent fluctuations in the required driving force result in a short period of time, from t11 to t17, when the required driving force and the actual driving force coincide. Therefore, the elapsed time for the restriction process is reset in a short period of time, preventing the elapsed time from increasing. Furthermore, if the amount of accelerator pedal 21 depressed fluctuates, the difference in driving force does not increase. Therefore, when the change rate is limited according to the driving operation during period T11, the change rate obtained from the limited change rate map 33 is also small, and the actual driving force does not change significantly. In other words, the vehicle can maintain a constant speed in accordance with the driver's intention.

[0074] As described above, in vehicle 1 according to Embodiment 1, actual driving force calculation unit 32 varies the rate of change of the actual driving force based on the difference between the requested driving force and the actual driving force and the elapsed time of the rate of change restriction process. Because the elapsed time of the restriction process is a parameter that accurately reflects the driving conditions, simple calculation processing by actual driving force calculation unit 32 can achieve a rate of change restriction of the driving force that is adapted to the driving conditions.

[0075] Furthermore, according to vehicle 1 of Embodiment 1, as shown in restricted change rate map 33, actual driving force calculation unit 32 decreases the change rate as the driving force difference decreases and the elapsed time shortens, and increases the change rate as the driving force difference increases and the elapsed time lengthens. Thus, at the start of a sudden acceleration / deceleration operation, the actual driving force is smoothly changed, mitigating the impact on the travel motor 11 and the power transmission path. Furthermore, even when the rapid acceleration / deceleration operation continues, the actual driving force can be greatly changed in accordance with the driver's intention, allowing the actual driving force to quickly approach the requested driving force.

[0076] Furthermore, in vehicle 1 according to the first embodiment, actual driving force calculation unit 32 resets elapsed timer 34 when the absolute value of the difference between the requested driving force and the actual driving force falls below a first threshold value. Thus, the elapsed time can represent the time since the actual driving force approached the requested driving force, and this elapsed time can be used to implement rate-of-change control that adapts to different driving conditions, such as starting and driving at a constant speed.

[0077] Furthermore, in the vehicle 1 of the first embodiment, since the power source generating the driving wheels 2 is the travel motor 11, the delay between the calculation of the actual driving force and its actual output by the travel motor 11 is minimal. Consequently, through the aforementioned rate-of-change limiting control, the calculated actual driving force is output from the travel motor 11 with minimal delay. Consequently, even under various driving conditions, it is possible to implement rate-of-change limiting control of the driving force that is adapted to each driving condition.

[0078] (Implementation Method 2)

[0079] The vehicle 1 of the second embodiment differs from the first embodiment in that zero cross control and a limit control based on a change rate of a predetermined driving condition are added, but the other configurations are the same as those of the first embodiment.

[0080] Figure 5 This is a flowchart showing the control process of the actual driving force calculation unit in the vehicle according to the second embodiment. During the system operation of the vehicle 1, the actual driving force calculation unit 32 continuously executes Figure 5 control processing.

[0081] The actual driving force calculation unit 32 of the second embodiment executes zero-cross control (steps S10-S11) and change rate limitation control (steps S12-S13) according to a predetermined driving situation in addition to the change rate control (steps S1-S9) shown in the first embodiment.

[0082] The processing of steps S1 to S9 implements the rate of change control described in Embodiment 1. Specifically, after receiving the requested driving force in step S1, the actual driving force calculation unit 32 determines whether to execute rate of change restriction processing and whether to start or end the series of restriction processes through the determination processing of steps S2, S3, and S5. Upon completion, the elapsed timer 34 is reset and stopped (step S6), and upon restart, the elapsed timer 34 is started (step S4). Furthermore, if the absolute value of the driving force difference exceeds the first threshold ("Yes" in step S2) or the rate of change of the requested driving force exceeds the level requiring restriction ("Yes" in step S3), the actual driving force calculation unit 32 determines that the rate of change restriction process is in progress. The actual driving force calculation unit 32 then determines the rate of change from the restricted rate of change map 33 (step S7) and calculates the actual driving force using the determined rate of change (step S8). On the other hand, if the actual driving force calculation unit 32 determines that the restriction process is not in progress, it calculates the actual driving force that matches the requested driving force (step S9).

[0083] Zero-cross control is a control that limits the rate of change of the driving force when the driving force of the travel motor 11 exceeds zero. When the driving force exceeds zero, the direction of the torque transmitted from the travel motor 11 to the drive wheel 2 changes, so there may be a collision caused by gear rattling in the power transmission mechanism from the travel motor 11 to the drive wheel 2. Zero-cross control is a control for suppressing such collisions. In zero-cross control, the actual driving force calculation unit 32 determines whether the actual driving force is within the zero vicinity range H1 (refer to Figure 6 ) (step S10), and when the actual driving force is within the near-zero range H1, the rate of change of the actual driving force is determined to be the first rate of change (or less) that suppresses the aforementioned collision (step S11). Furthermore, the actual driving force calculation unit 32 calculates the actual driving force using the determined rate of change (step S8). It should be noted that the processing content of steps S10 and S11 is merely an example of zero-cross control. As long as the actual driving force that suppresses the aforementioned collision can be calculated, any method for determining the conditions and the rate of change can be used.

[0084] The rate-of-change limit control corresponding to a predetermined driving condition is designed to achieve a smoother temporal change in the rate of change of the actual driving force, in situations where the rate of change of the actual driving force would change dramatically if only the rate-of-change control based on the difference between the required driving force and the actual driving force were executed. Predetermined driving conditions include situations where the absolute value of the required driving force is large at the end of zero-cross control, and situations where the accelerator pedal is depressed (the accelerator's driving operation variable changes stepwise from a first operation variable greater than zero to a second operation variable greater than the first operation variable) while the actual driving force has not yet caught up with the required driving force. In this rate-of-change limit control, the actual driving force calculator 32 determines whether the predetermined driving condition exists during the rate-of-change limit process (step S12). If so, it resets the elapsed timer 34 (step S13). The actual driving force calculator 32 then proceeds to step S7, where the rate of change is determined from the rate-of-change limit map 33.

[0085] <Action Example 3>

[0086] Figure 6 This is a timing chart showing an example of the operation of the vehicle according to the second embodiment. Figure 7 This is a timing diagram showing a comparative example. Operation Example 3 shows the operation before and after zero-cross control is performed. The comparative example shows the operation of a vehicle that does not have a rate-of-change limiting control function corresponding to a predetermined driving situation. In Operation Example 3, it is assumed that a driving mode is selected in which operation of the accelerator pedal 21 allows both braking and acceleration (a braking force is generated when the operation amount is zero).

[0087] like Figure 7 As shown, when the accelerator pedal 21 operation amount (acceleration / deceleration operation amount) increases from zero to a certain value while the vehicle is traveling, the required driving force increases proportionally with the operation amount, and the actual driving force also changes from a deceleration value (regenerative operation of the travel motor 11) to an acceleration value (power operation of the travel motor 11). In this case, during period T31 when the actual driving force is within the range H1 near zero, the actual driving force calculation unit of the comparative example performs zero-cross control, limiting the rate of change of the actual driving force to the first rate of change used for zero-cross control. This prevents the occurrence of a collision when the actual driving force exceeds zero.

[0088] During zero-cross control, if the accelerator pedal 21 is operated with an increased or maintained high amount, the rate of change during period T31 is kept low, resulting in a larger difference between the requested and actual driving forces in the final stage of period T31. Furthermore, when zero-cross control ends and the system switches to limiting the rate of change of the difference between the requested and actual driving forces, the rate of change of the actual driving force increases dramatically (time t31). This sudden increase in the rate of change can cause discomfort to the driver.

[0089] Figure 6 The example of the operation of the vehicle 1 in the second embodiment is shown. Figure 7 The same driving situation. In the vehicle 1 of the second embodiment, the zero cross control is also performed during the period T21 when the actual driving force is in the zero vicinity range H1, and the driving force difference becomes larger at the end of the period T21. However, in the vehicle 1 of the second embodiment, when the actual driving force calculation unit 32 determines the end time of the zero cross control ( Figure 5 In the case of step S12 of FIG. 1 , the actual driving force calculation unit 32 resets the elapsed timer 34 ( Figure 5 Then, based on the difference between the elapsed time after the reset and the driving force, the rate of change is determined and the actual driving force is calculated ( Figure 5 Steps S7 and S8).

[0090] By resetting the elapsed timer 34, at the moment t21 when the rate of change of the zero-cross control is switched to the rate of change of the rate-limited change map 33, the timer value of the elapsed timer 34 becomes a small value, and a small rate of change is read from the rate-limited change map 33. Therefore, in the period T22 immediately after the moment t21, a sharp increase in the rate of change of the actual driving force can be avoided. And, thereafter, since the difference in the driving force is still large and the elapsed time becomes longer, the rate of change gradually increases to a larger value (period T23). By such a rate-limited control, the sudden increase in the rate of change of the actual driving force can be eliminated. Figure 7 The rapid increase in the rate of change produced in the comparative example of is achieved by increasing the actual driving force in accordance with the driver's intention without causing discomfort to the driver.

[0091] <Action Example 4>

[0092] Figure 8 This is a timing chart showing an example of the operation of the vehicle according to the second embodiment. Figure 9 This is a timing chart showing a comparative example. Example 4 illustrates the operation when the accelerator pedal 21 is depressed (the accelerator driving operation amount is changed in steps from a first operation amount greater than zero to a second operation amount greater than the first operation amount) during vehicle start. The comparative example illustrates the operation when the rate of change restriction control corresponding to the predetermined driving situation of Embodiment 2 is not performed.

[0093] During acceleration such as starting, the driver depresses the accelerator pedal at one level. When the actual driving force approaches the required driving force and the increase in the actual driving force becomes gradual, the driver may further depress the accelerator pedal 21 at another level if he wishes to accelerate further.

[0094] like Figure 9As shown, if the accelerator pedal 21 is operated as described above, such as during a start, the driving force difference increases rapidly after time t51, immediately following the accelerator pedal's depressing. In this case, the timing time in the comparative example also increases, so the rate of change obtained from the limited rate of change map reaches a large value, causing the rate of change to change rapidly around time t51. Such a sudden change in the rate of change can cause discomfort to the driver.

[0095] Figure 8 The vehicle 1 of the second embodiment shows a case where the same driving operation as above is performed during acceleration such as when starting. In the vehicle 1 of the second embodiment, when the driving operation as above is performed, the actual driving force calculation unit 32 determines whether the accelerator pedal 21 is depressed ( Figure 5 Step S12), and based on the determination result, the elapsed timer 34 ( Figure 5 Then, based on the difference between the elapsed time after the reset and the driving force, the rate of change is determined and the actual driving force is calculated ( Figure 5 Steps S7 and S8).

[0096] By resetting the elapsed timer 34, the timer value of the elapsed timer 34 becomes smaller after the moment t41 immediately after the accelerator pedal 21 is stepped on, and a small rate of change is read from the rate of change limit map 33. Therefore, in the period immediately after the moment t41, a sharp increase in the rate of change of the actual driving force can be avoided. And, since the time elapsed in the state where the driving force difference is large becomes longer, the rate of change gradually increases to a larger value (period T41). By limiting the rate of change in this way, the Figure 9 The rapid increase in the rate of change produced in the comparative example of is eliminated, and the actual driving force is increased in accordance with the driver's intention without causing discomfort to the driver.

[0097] As described above, according to the vehicle 1 of the second embodiment, when a predetermined driving situation is identified in which the rate of change of the actual driving force would change rapidly using only rate of change control based on the difference between the required driving force and the actual driving force, the elapsed timer 34 is reset. Therefore, immediately after the occurrence of the predetermined driving situation, the actual driving force calculation unit 32 reads the rate of change corresponding to a short elapsed time from the restricted rate of change map 33 and uses this rate of change to calculate the actual driving force. Therefore, even when the predetermined driving situation occurs, the same rate of change as that used immediately after the actual driving force deviates from the required driving force is used, thereby suppressing rapid changes in the rate of change of the actual driving force. More specifically, resetting the elapsed timer 34 at the end of zero-cross control and when the accelerator pedal 21 is depressed can suppress rapid changes in the rate of change of the actual driving force. Consequently, rate of change control of the actual driving force that conforms to the driver's wishes can be achieved without causing discomfort to the driver.

[0098] The above describes various embodiments of the present invention. However, the present invention is not limited to the above embodiments. For example, in the above embodiments, driving force is described as the calculation target, but driving force can also be replaced with torque. Because driving force and torque have a predetermined relationship, a configuration in which torque is used as the calculation target is considered equivalent to a configuration in which driving force is used as the calculation target. In addition, in the above embodiments, an example of zero-cross control is shown in a driving mode in which braking and acceleration can be performed only by operating the accelerator pedal 21. However, zero-cross control can also be performed in a driving mode in which braking and acceleration can be performed by operating the brake pedal 22 and the accelerator pedal 21. Furthermore, in the above embodiments, a configuration is shown in which the actual driving force calculation unit uses map data (limited change rate map) to calculate the change rate corresponding to the difference in driving force and the elapsed time. However, the actual driving force calculation unit can also use a configuration in which a function, etc. is used to calculate the change rate corresponding to the difference in driving force and the elapsed time. Furthermore, the embodiments illustrate an example in which a limited rate-of-change map using the absolute value of the driving force difference as a parameter is used, and the rate of change determined when the driving force difference is positive and when it is negative is symmetrical. However, the rate of change determined based on the driving force difference and elapsed time may be asymmetrical when the driving force difference is positive and when it is negative, or / and when the required driving force or actual driving force is positive and when it is negative. Furthermore, while the above embodiments illustrate an EV vehicle, the present invention is also applicable to HEVs and, if high responsiveness of driving force control can be achieved, to engine vehicles. Furthermore, while the second embodiment illustrates the termination of zero-cross control and the accelerator pedal being depressed as predetermined driving conditions, other driving conditions in which the rate of change of the actual driving force changes dramatically when only the rate of change control based on the difference between the required driving force and the actual driving force is executed may also be employed. Furthermore, the details shown in the embodiments may be modified as appropriate without departing from the spirit of the invention.

Claims

1. A vehicle, characterized in that: have: a power source, which generates power; a requested driving force calculation unit that calculates the requested driving force based on the driving operation; an actual driving force calculation unit for calculating an actual driving force that follows the required driving force while limiting a rate of change; as well as a drive control unit that drives the power source so as to output the calculated actual driving force, The actual driving force calculation unit changes the rate of change of the actual driving force based on the difference between the required driving force and the actual driving force and the elapsed time during which the rate of change of the actual driving force is limited. The actual driving force calculation unit increases the rate of change as the difference is larger and the elapsed time is longer, and decreases the rate of change as the difference is smaller and the elapsed time is shorter.

2. The vehicle according to claim 1, characterized in that The actual driving force calculation unit resets the elapsed time on the condition that the absolute value of the difference between the required driving force and the actual driving force becomes equal to or smaller than a first threshold value.

3. The vehicle according to claim 1, wherein: The actual driving force calculation unit resets the elapsed time when a predetermined driving condition is determined.

4. The vehicle according to claim 2, characterized in that The actual driving force calculation unit resets the elapsed time when a predetermined driving condition is determined.

5. The vehicle according to claim 3, characterized in that When the actual driving force exceeds zero, the actual driving force calculation unit performs zero-cross control to limit the rate of change of the actual driving force. The predetermined driving condition includes the termination of the zero-cross control.

6. The vehicle according to claim 4, characterized in that When the actual driving force exceeds zero, the actual driving force calculation unit performs zero-cross control to limit the rate of change of the actual driving force. The predetermined driving condition includes the termination of the zero-cross control.

7. The vehicle according to claim 3, characterized in that The predetermined driving condition includes a case where the driving operation amount of acceleration changes in a stepwise manner from a first operation amount greater than zero to a second operation amount greater than the first operation amount.

8. The vehicle according to claim 4, characterized in that The predetermined driving condition includes a case where the driving operation amount of acceleration changes in a stepwise manner from a first operation amount greater than zero to a second operation amount greater than the first operation amount.

9. The vehicle according to claim 5, characterized in that The predetermined driving condition includes a case where the driving operation amount of acceleration changes in a stepwise manner from a first operation amount greater than zero to a second operation amount greater than the first operation amount.

10. The vehicle according to claim 6, characterized in that The predetermined driving condition includes a case where the driving operation amount of acceleration changes in a stepwise manner from a first operation amount greater than zero to a second operation amount greater than the first operation amount.

11. The vehicle according to any one of claims 1 to 10, characterized in that: The power source is an electric motor, Power is transmitted from the electric motor to the drive wheels.

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