Drive control system

Abstract

To provide a drive control system which prevents insufficient acceleration for adjusting a vehicle speed to a setting speed during cruise control and also prevents deterioration of drivability.SOLUTION: An ECU 20 commands a drive device 13 to generate an initial driving force while setting a maximum driving force which does not need downshifting to the initial driving force if a target driving force exceeds a driving force which needs downshifting and reduction of the acceleration caused by downshifting during initial acceleration is larger than or equal to a predetermined threshold value during cruise control in which a vehicle speed is automatically adjusted to a setting speed. After the driving force of the drive device 13 reaches the initial driving force, the ECU 20 commands the drive device 13 to generate the target driving force.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive control system including a drive unit having a prime mover and a transmission mechanism that changes the drive of the prime mover, and a control device that commands a drive force to the drive unit, adjusts the vehicle speed to a set speed, and switches the gear stages of the transmission mechanism using the drive force. [Background technology]

[0002] In the drive control of a vehicle, an automatic transmission and a cruise control function are known. An automatic transmission can automatically change the gear ratio of a transmission mechanism of a drive unit. Also, a cruise control function can regulate the vehicle speed to a set speed.

[0003] A drive control system equipped with an automatic transmission and cruise control function detects the difference in speed between the vehicle speed and a speed set by the driver, and automatically controls the driving force of the prime mover and the gear stage of the transmission mechanism based on the speed difference to adjust the vehicle speed to the set speed (for example, Patent Document 1).

[0004] In the above drive control system, when the vehicle approaches a road surface with a high driving load, such as an uphill road, the vehicle speed temporarily drops, so the driving force of the prime mover is increased to adjust the vehicle speed to the set speed. On the other hand, when the driving force of the prime mover is increased, the gear stage of the transmission mechanism is lowered to adjust the vehicle speed to the set speed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-120268 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the drive control system disclosed in Patent Document 1, for example, when the drive force is increased to lower the gear stage of the transmission mechanism (downshift) during cruise control, the drive force is changed to a command that does not downshift. This prevents the downshift from deteriorating drivability. However, this means that there is a lack of acceleration to adjust the vehicle speed to the set speed.

[0007] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a drive control system that does not cause a shortage of acceleration for adjusting the vehicle speed to a set speed during cruise control and does not impair drivability. [Means for solving the problem]

[0008] The drive control system of the present invention comprises a drive unit having a prime mover and a transmission mechanism that changes the drive of the prime mover, and a control device that commands a drive force to the drive unit, adjusting the vehicle speed to a set speed and switching the gear stages of the transmission mechanism using the drive force.The control device is characterized in that, during cruise control that automatically adjusts the vehicle speed to the set speed, when the target drive force exceeds the drive force for downshifting and the drop in acceleration due to downshifting during initial acceleration exceeds a predetermined threshold, the control device commands the drive unit to the maximum drive force without downshifting as the initial drive force, and after the drive force of the drive unit reaches the initial drive force, commands the drive unit to the target drive force. Effect of the Invention

[0009] According to the drive control system of the present invention, there is no shortage of acceleration for adjusting the vehicle speed to a set speed during cruise control, and drivability is not impaired. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating a drive control system according to an embodiment; [Diagram 2]4 is an automatic shift diagram showing a second driving force, a third driving force, and a fourth driving force. [Diagram 3] FIG. 4 is a flow chart showing a flow of drive control. [Figure 4] 5 is a time series diagram showing a comparison between a drive control according to an embodiment and a conventional drive control. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [Drive control system] A drive control system 10 as an example of an embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0012] As shown in Fig. 1, a drive control system 10 controls the driving of a vehicle. The drive control system 10 includes a prime mover 11, a drive device 13 having a transmission mechanism 12 that changes the speed of the drive of the prime mover 11, and an ECU (Electronic Control Unit) 20 as a control device that commands the drive force to the drive device 13. As will be described in detail later, the drive control system 10 ensures that there is no shortage of acceleration for adjusting the vehicle speed during cruise control to a set speed, and does not impair drivability.

[0013] The prime mover 11 may be an engine, a motor, or an engine and a motor. The transmission mechanism 12 is an automatic transmission that automatically changes gears. In other words, the vehicle is an automatic vehicle (AT vehicle).

[0014] The ECU 20 issues a command for a necessary driving force to the drive device 13. The ECU 20 may be composed of a plurality of ECUs that control the devices of the vehicle. The ECU 20 has a central processing unit (CPU) that is an arithmetic processing unit, and storage units such as a random access memory (RAM) and a read only memory (ROM), and performs signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM.

[0015] The ECU 20 is connected to the prime mover 11 and issues a command for a required driving force. The ECU 20 is also connected to the transmission mechanism 12 and issues a command for an appropriate gear stage according to the driving force and vehicle speed.

[0016] The ECU 20 is connected to a vehicle speed sensor 41 that detects the vehicle speed and acquires the vehicle speed. The ECU 20 is also connected to an acceleration sensor 42 that detects the acceleration of the vehicle and acquires the acceleration of the vehicle.

[0017] As will be described in detail later, during cruise control that adjusts the vehicle speed to a set speed, the ECU 20 calculates a target driving force that achieves acceleration for adjusting the vehicle speed to the set speed, commands the maximum driving force without downshifting as the initial driving force to the drive unit 13, and performs drive control to command the target driving force to the drive unit 13 after the driving force of the drive unit 13 reaches the initial driving force.

[0018] In other words, the ECU 20 commands the driving force in two stages and accelerates in two stages, thereby eliminating the drop in acceleration during the initial acceleration and preventing the loss of drivability (see FIG. 3(C)).

[0019] The ECU 20 has a cruise control execution unit 21, a first acceleration calculation unit 22, a first driving force calculation unit 23, a second driving force calculation unit 24, a third driving force calculation unit 25, an acceleration drop determination unit 26, a fourth driving force calculation unit 27, a second acceleration calculation unit 28, a fourth driving force command unit 29, a second acceleration arrival determination unit 30, and a first driving force command unit 31. These are realized by the CPU executing programs stored in the ROM or RAM.

[0020] The cruise control execution unit 21 executes cruise control. Specifically, the cruise control execution unit 21 detects the speed difference between the set speed set by the driver and the vehicle speed, and controls the driving force of the prime mover 11 and the gear stage of the transmission mechanism 12 based on the speed difference to adjust the vehicle speed to the set speed.

[0021] The first acceleration calculation unit 22 calculates a target acceleration (hereinafter, the first acceleration) as an acceleration required for the vehicle speed to become a set speed during cruise control by the cruise control execution unit 21. For example, when the vehicle approaches a road surface with a large driving load such as an uphill road, the first acceleration calculation unit 22 calculates the first acceleration for accelerating the vehicle speed to the set speed since the vehicle speed temporarily decreases.

[0022] The first driving force calculation unit 23 calculates a first driving force T1 as a target driving force required for the driving device 13 to realize the first acceleration calculated by the first acceleration calculation unit 22.

[0023] Here, FIG. 2 will be described. FIG. 2 is an automatic shift diagram showing vehicle speed on the horizontal axis and driving force on the vertical axis. The shift line in FIG. 2 shows the driving force required for downshifting with respect to the vehicle speed in the range of vehicle speed to which the current gear stage is applied. In FIG. 2, the range of driving force above the shift line shows the range of driving force required for downshifting from the current gear stage. On the other hand, the range of driving force below the shift line shows the range of driving force that can be output without downshifting from the current gear stage. The second driving force T2 shown in FIG. 2 is the minimum driving force required to lower (downshift) the current gear stage of the transmission mechanism 12 at the current vehicle speed. In addition, the second driving force T2 is also the maximum driving force required to lower (downshift) the current gear stage of the transmission mechanism 12 at the current vehicle speed. Therefore, if the target driving force becomes larger than the second driving force T2, a downshift occurs, causing a drop in acceleration.

[0024] 2 is a driving force obtained by subtracting a margin of operation from the second driving force T2, and is a driving force that will certainly not cause a downshift at the current vehicle speed. The fourth driving force T4 is included in the "maximum driving force that will not cause a downshift."

[0025] Here, if a downshift occurs and the drop in acceleration during initial acceleration exceeds a predetermined amount, hesitation occurs. Hesitation is a delay in the increase in rotation of the engine 11 when the accelerator pedal is depressed, a shock caused by a temporary stall feeling, or a "sluggishness." When hesitation occurs, drivability is impaired.

[0026] The amount of drop in acceleration when downshifting is determined by the driving force and the vehicle speed. The correlation between the amount of drop in acceleration and the driving force and the vehicle speed is calculated based on the vehicle weight, the inertia of the transmission mechanism 12 for each gear shift type, and the tire diameter.

[0027] The amount of acceleration drop during a downshift becomes smaller when the target driving force becomes larger to a certain extent. Line a in FIG. 2 indicates the boundary line where the amount of acceleration drop during a downshift becomes smaller than a predetermined threshold. In the range above line a, the amount of acceleration drop becomes smaller than the predetermined threshold, and in the range below line a, the amount of acceleration drop becomes larger than the predetermined threshold. Here, the third driving force T3 shown in FIG. 2 indicates the minimum target driving force at which the amount of acceleration drop becomes smaller than the predetermined threshold. Therefore, when the target driving force is larger than the third driving force T3, the amount of acceleration drop becomes smaller than the predetermined threshold, and when the target driving force becomes smaller than the third driving force T3, the amount of acceleration drop becomes larger than the predetermined threshold.

[0028] Returning to FIG. 1, the second driving force calculation unit 24, the third driving force calculation unit 25 and the fourth driving force calculation unit 27 of the ECU 20 calculate the second driving force, the third driving force and the fourth driving force.

[0029] The acceleration drop determination unit 26 determines whether a downshift occurs and the amount of drop in acceleration during initial acceleration occurs by a predetermined amount or more when the first driving force T1 is commanded. Specifically, the acceleration drop determination unit 26 determines whether the first driving force T1 is greater than the second driving force T2 and less than the third driving force T3.

[0030] When the acceleration drop determination unit 26 determines that a downshift occurs when the first driving force is commanded and the amount of drop in acceleration during initial acceleration occurs by a predetermined amount or more, the fourth driving force calculation unit 27 calculates a fourth driving force T4 as an initial driving force that is smaller than the above-mentioned second driving force T2 by a predetermined driving force.

[0031] A second acceleration calculation unit 28 calculates a second acceleration as an initial acceleration realized by the fourth driving force T4 calculated by the fourth driving force calculation unit 27. A fourth driving force command unit 29 commands the fourth driving force T4 to the prime mover 11. A second acceleration reach determination unit 30 checks whether the acceleration of the vehicle has reached the second acceleration.

[0032] [Drive control flow] The flow of drive control will be described with reference to FIG.

[0033] The drive control commands the driving force to the prime mover 11 based on each function of the ECU 20 described above in accordance with the following procedure.

[0034] In step S11, the ECU 20 checks whether or not the cruise control is being performed by the cruise control execution unit 21. If the cruise control function is being executed, the process proceeds to step S12.

[0035] In step S12, the ECU 20 uses the first acceleration calculation unit 22 to calculate a first acceleration as a target acceleration for adjusting the vehicle speed to a set speed during cruise control. In step S13, the first driving force calculation unit 23 calculates a first driving force required to achieve the first acceleration. In step S14, the ECU 20 uses the second driving force calculation unit 24 to calculate a second driving force which is the maximum driving force at which a downshift does not occur at the current vehicle speed.

[0036] In step S15, the ECU 20 determines whether the first driving force is greater than the second driving force. If the first driving force is greater than the second driving force, the ECU 20 proceeds to step S16. If the first driving force is equal to or less than the second driving force, the ECU 20 proceeds to step S22.

[0037] In step S16, the ECU 20 calculates the third driving force, which is the maximum driving force at which a downshift occurs at the current vehicle speed and the amount of drop in acceleration during initial acceleration is equal to or greater than a predetermined amount, by the third driving force calculation unit 25. This calculation may be performed based on, for example, a preset line a in FIG.

[0038] In step S17, the ECU 20 determines whether the first driving force is smaller than the third driving force. As described above, if the first driving force is smaller than the third driving force, the amount of drop in acceleration during a downshift is smaller than a predetermined threshold. In this case, the ECU 20 proceeds to step S18. If the first driving force is equal to or greater than the third driving force, the ECU 20 proceeds to step S22.

[0039] In step S18, the ECU 20 calculates a fourth driving force that is smaller than the second driving force by a predetermined driving force using the fourth driving force calculation unit 27. In step S19, the ECU 20 calculates a second acceleration realized by the fourth driving force using the second acceleration calculation unit 28. In step S20, the ECU 20 commands the prime mover 11 to use the fourth driving force command unit 29.

[0040] In step S21, the ECU 20 determines whether the acceleration of the vehicle reaches the second acceleration by driving the prime mover 11 with the fourth driving force using the second acceleration reach determination unit 30. If the second acceleration has been reached, the ECU 20 proceeds to step S22. In step S22, the ECU 20 issues a first driving force command to the prime mover 11 using the first driving force command unit 31.

[0041] [Comparison with conventional drive control] Here, a comparison between the drive control of this embodiment and a conventional drive control will be described with reference to Fig. 4(A) to Fig. 4(C). Fig. 4(A) and Fig. 4(C) are time series change diagrams showing time on the horizontal axis and drive force on the vertical axis. Fig. 4(B) is a time series change diagram showing time on the horizontal axis and gear stages of the speed change mechanism 12 on the vertical axis.

[0042] In Fig. 4, the solid line indicates the time series change of the drive control of this embodiment. The dashed line indicates the time series change of conventional drive control 1, which downshifts as is when a downshift would be performed at the target drive force during cruise control. The dashed and dotted line indicates conventional drive control 2 (e.g., Patent Document 1), which changes the command to a drive force that does not downshift when a downshift would be performed at the target drive force during cruise control.

[0043] In the conventional control shown by the dashed lines in Figures 3(A) to 3(C), the drop in acceleration during initial acceleration is large, causing the driver to feel hesitation. Also, in the conventional control shown by the dashed lines in Figures 3(A) to 3(C), control is performed to prevent downshifting, resulting in a lack of acceleration to adjust the vehicle speed to the set speed.

[0044] In contrast, as shown by the solid lines in Figures 4(A) and 4(B), in the drive control of this embodiment, a target drive force (first drive force T1) that realizes acceleration for adjusting to the set speed is calculated during cruise control, and the maximum drive force (second drive force T2) that does not cause downshifting is commanded to the drive unit 13 as the initial drive force, and after the drive force of the drive unit 13 reaches the initial drive force, drive control is performed to command the target drive force to the drive unit 13.

[0045] As a result, as shown by the solid line in Fig. 4(C), a downshift occurs after reaching the initial acceleration corresponding to the second driving force T2, causing a drop in acceleration, but the driver does not feel hesitation because the drop in acceleration does not occur during the initial acceleration. Also, there is no shortage of acceleration to adjust the vehicle speed to the set speed, as in the conventional drive control 2 that interprets the command as a driving force that does not cause a downshift.

[0046] As described above, according to the drive control system 10 of the embodiment, the acceleration required to adjust the vehicle speed to a set speed during cruise control is not insufficient, and drivability is not impaired. [Explanation of symbols]

[0047] 10 Drive control system, 11 Prime mover, 12 Transmission mechanism, 13 Drive unit, 20 ECU (control unit), 21 Cruise control control execution unit, 22 First acceleration calculation unit, 23 First driving force calculation unit, 24 Second driving force calculation unit, 25 Third driving force calculation unit, 26 Acceleration drop determination unit, 27 Fourth driving force calculation unit, 28 Second acceleration calculation unit, 29 Fourth driving force command unit, 30 Second acceleration arrival determination unit, 31 First driving force command unit, 41 Speed ​​sensor, 42 Acceleration sensor

Claims

[Claim 1] A drive device having a prime mover and a speed change mechanism that changes the speed of the drive of the prime mover; a control device that commands a driving force to the drive device, and adjusts a vehicle speed to a set speed and switches a gear stage of the transmission mechanism by the driving force; The control device includes: During cruise control that automatically adjusts the vehicle speed to the set speed, when the target driving force exceeds the driving force for downshifting and a drop in acceleration due to the downshift during initial acceleration reaches or exceeds a predetermined threshold, a maximum driving force that does not cause a downshift is commanded to the drive device as an initial driving force; After the driving force of the driving device has reached the initial driving force, the driving device is commanded to the target driving force. Drive control system.

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