JP6757510B2 - Speed change control device for automatic transmission - Google Patents

Description

The present invention relates to a shift control device for an automatic transmission, and more particularly to a shift control device for an automatic transmission in which the braking force due to engine braking during traveling is not suddenly changed.

The automatic transmission mounted on the vehicle controls the shift stage according to the traveling condition by the shift control device to shift the driving force generated by the engine and drive the drive wheels. In such a shift control device of an automatic transmission, control is performed in which the braking force caused by the engine brake is applied by shifting the shift stage to the low speed stage side while the vehicle is traveling on a downhill road. When the gear is changed to the low speed gear side excessively, there is a problem that braking force is generated due to excessive engine braking.
Therefore, Patent Document 1 discloses a shift control device for suppressing the generation of braking force due to excessive engine braking due to excessive shift to the low speed stage side while traveling on a downhill road.

JP-A-2009-14105

However, the shift control device of Patent Document 1 automatically shifts when the driver's braking operation (brake pedal depression operation) is detected during traveling by shifting the gear to the low speed side while traveling on a downhill road. The gear ratio of the machine is further increased, that is, the gear is changed to the low speed stage side.
Therefore, in the shift control device of Patent Document 1, as a result of shifting the automatic transmission to the lower speed stage side by detecting the braking operation, the braking force due to the engine brake becomes excessive or the road surface gradient suddenly changes. There is a possibility that the braking force due to the engine brake will be excessive.

In order to prevent the braking force due to the engine brake from suddenly changing and becoming excessive in this way, it is conceivable to shift the shift stage to the high speed stage side to reduce the braking force due to the engine brake.
However, in a vehicle equipped with an automatic transmission having a clutch that disconnects (disconnects or connects) the driving force transmission between the engine and the driving wheels, if the shifting is performed while driving using the braking force of the engine brake. , The clutch is temporarily disengaged due to shifting.
For this reason, the braking force due to the engine brake is reduced, the vehicle accelerates even when braking is requested (when non-acceleration is requested), and the occupant feels uncomfortable due to the discrepancy between the driving operation and the vehicle behavior. There is a problem, and improvement is desired.

According to the present invention, when a non-acceleration request is made, the clutch is controlled based on the driving force of the engine and the braking force caused by the engine brake, so that the braking force caused by the engine brake suddenly changes without performing the brake control. It is an object of the present invention to provide a shift control device for an automatic transmission that prevents this from occurring.

The present invention is a shift control device for an automatic transmission having a clutch that engages and disengages the transmission of driving force between the engine and the drive wheels, the clutch control unit that controls the engagement and disengagement of the clutch, and the shift stage of the automatic transmission. A shift stage control unit that controls the engine brake, a braking force calculation unit that calculates the braking force caused by the engine brake, and an acceleration force calculation unit that calculates the vehicle acceleration force that acts on the vehicle to accelerate the vehicle . The vehicle acceleration force calculated by the acceleration force calculation unit exceeds the acceleration force threshold set as the acceleration force of the vehicle above a certain level on a downhill road, and the vehicle acceleration force and braking force calculation unit calculated by the acceleration force calculation unit When the difference from the calculated braking force due to engine braking is less than the clutch operation threshold, which is the clutch operation threshold that can be set at each shift stage, the shift stage control unit shifts the shift stage to the high speed stage side. The clutch control unit is characterized in that the clutch is controlled in a semi-engaged state based on the braking force generated by the engine brake calculated by the braking force calculation unit.

The present invention prohibits the shift stage from being shifted to the high speed stage side based on the braking force caused by the engine brake, and controls the clutch in a semi-engaged state. It is possible to prevent the braking force due to the engine brake from suddenly changing by performing the shifting operation.

FIG. 1 is a system configuration diagram of a shift control device for an automatic transmission. (Example) FIG. 2 is a flowchart of control by the shift control device. (Example) FIG. 3 is a diagram showing the relationship between the clutch rotation speed / engine rotation speed / vehicle speed during traveling, the braking force due to the vehicle acceleration force / engine braking force, and the clutch position. (Example)

The present invention has the purpose of preventing a sudden change in the braking force caused by the engine brake, prohibiting the shift stage from being shifted to the high speed stage side based on the braking force caused by the engine brake, and half-engaging the clutch. It is realized by controlling the condition.

Hereinafter, examples of the present invention will be described with reference to the drawings. As shown in FIG. 1, the engine 2 mounted on the vehicle 1 has a crankshaft 3 that outputs a driving force. An automatic transmission 5 having a clutch 4 is connected to the engine 2. The automatic transmission 5 includes an input shaft 6 and an output shaft 7.
The clutch 4 is arranged between the crankshaft 3 of the engine 2 and the input shaft 6 of the automatic transmission 5, and disconnects (disconnects or connects) the driving force transmitted from the engine 2 to the automatic transmission 5. The clutch 4 is engaged and disconnected by the clutch actuator 8. The automatic transmission 5 is a transmission mechanism having a plurality of gears 9 (for example, 1st to 5th gears, reverse gears, etc.) capable of shifting the driving force between the input shaft 6 and the output shaft 7. 10 is provided. The shift stage 9 is changed by the shift actuator 11.
As a result, the automatic transmission 5 can shift to any one of the clutch actuator 8 capable of engaging and disengaging the clutch 4 and the plurality of gears 9 to the manual transmission having the plurality of gears 9 (driving force transmission state). It is an automatic transmission (AMT: Automatic Manual Transmission) provided with a shift actuator 11 that can be coupled to.
In the automatic transmission 5, the differential device 13 is connected to the output shaft 7 via the final reduction gear train 12. The drive wheels 15 are connected to the differential device 13 by the drive shaft 14. The driving force of the engine 2 is transmitted from the automatic transmission 5 to the differential device 13 via the final reduction gear train 12, and the drive shaft 14 drives the drive wheels 15. As a result, the clutch 4 of the automatic transmission 5 connects and disconnects the driving force transmission between the engine 2 and the driving wheels 15.

The automatic transmission 5 having a clutch 4 that engages and disconnects the driving force transmission between the engine 2 and the drive wheels 15 is controlled by the shift control device 16 between the engagement and disengagement of the clutch 4 and the shift of the shift stage 9.
The shift control device 16 includes a control unit 17. The clutch actuator 8 and the shift actuator 11 are connected to the output side of the control unit 17. The engine speed detection unit 18, the vehicle speed detection unit 19, the shift stage detection unit 20, the clutch position detection unit 21, and the gradient detection unit 22 are connected to the input side of the control unit 17.
The engine speed detection unit 18 detects the engine speed. The vehicle speed detection unit 19 detects the speed of the vehicle 1. The shift stage detection unit 20 detects a gear shift (shift stage in a driving force transmission state) among a plurality of shift stages 9 of the automatic transmission 5. The clutch position detection unit 21 detects the disengagement state (clutch position) of the clutch 4. The gradient detection unit 22 detects the gradient (inclined state with respect to the horizontal) of the road surface on which the vehicle 1 travels.

The control unit 17 of the shift control device 16 includes a clutch control unit 23 that controls the engagement and disengagement of the clutch 4, a shift stage control unit 24 that controls the shift stage 9 of the automatic transmission 5, and a braking force (braking force) caused by engine braking. The braking force calculation unit 25 that calculates Fb), the acceleration force calculation unit 26 that calculates the vehicle acceleration force (force that acts on the vehicle 1 to accelerate: Fa), and the downhill road that detects that the road surface is a downhill road. It includes a detection unit 27.
The clutch control unit 23 operates the clutch actuator 8 to control the engagement and disengagement of the clutch 4. The engagement and disengagement of the clutch 4 is determined by the clutch position detected by the clutch position detection unit 21. The shift stage control unit 24 operates the shift actuator 11 to control the shift of the shift stage 9 of the automatic transmission 5. The shift of the shift stage 9 is determined by the shift stage detected by the shift disconnection detection unit 20.
The braking force calculation unit 25 determines the braking force (Fb) caused by the engine brake from the engine speed detected by the engine speed detection unit 18 and the speed change 9 in the driving force transmission state detected by the speed change detection unit 20. calculate. The braking force (Fb) is Fb = (each engine speed friction) * (gear ratio of gear ratio 9 in the driving force transmission state) * (gear ratio of final reduction gear train 12) * (transmission efficiency) / (drive wheel) 15 turning radius) ... (N: SI unit), calculated from the formula.
The acceleration force calculation unit 26 calculates the vehicle acceleration force (Fa) from the vehicle speed detected by the vehicle speed detection unit 19. The vehicle acceleration force (Fa) is obtained from the formula of Fa = (weight of vehicle 1) * (Δ vehicle speed ... time change rate of vehicle speed) ... (N: SI unit). The downhill road detection unit 27 detects from the slope of the road surface detected by the slope detection unit 22 that the road surface on which the vehicle 1 travels is a downhill road (a road surface that inclines downward with respect to the traveling direction of the vehicle 1).

The shift stage control unit 24 that controls the shift stage 9 of the automatic transmission 5 prohibits the shift stage 9 from shifting to the high speed stage side based on the braking force (Fb) calculated by the braking force calculation unit 25. .. Further, the clutch control unit 23 that controls the engagement and disengagement of the clutch 4 controls the clutch 4 in a semi-engaged state based on the braking force (Fb) calculated by the braking force calculation unit 25.
In the embodiment, the shift stage control unit 24 uses the shift stage 9 based on the braking force (Fb) calculated by the braking force calculation unit 25 and the vehicle acceleration force (Fa) calculated by the acceleration force calculation unit 26. Is prohibited from shifting to the high speed stage side. The clutch control unit 23 controls the clutch 4 in a semi-engaged state based on the braking force (Fb) calculated by the braking force calculation unit 25 and the vehicle acceleration force (Fa) calculated by the acceleration force calculation unit 26. To do.
At this time, the clutch control unit 23 controls the engaged state of the clutch 4 so as to keep the braking force (Fb) calculated by the braking force calculation unit 25 constant.
Further, the shift stage control unit 24 prohibits the shift stage 9 of the automatic transmission 5 from shifting to the high speed stage side when the downhill road detection unit 27 detects the downhill road. When the downhill road detection unit 27 detects that the clutch control unit 23 is on a downhill road, the clutch control unit 23 controls the clutch 4 in a semi-engaged state.

Next, the action will be described.
As shown in FIG. 2, the speed change control device 16 of the automatic transmission 5 detects by the control unit 17 that the road surface on which the vehicle 1 travels is a downhill road, and the speed change control unit 24 detects the road surface on which the vehicle 1 travels. When the control program is started (t0 in FIG. 3) while shifting the gear 9 to the low speed side (step A01), the control caused by the engine brake is applied to the gear 9 in the engine speed and driving force transmission state. The power (Fb) is calculated by the braking force calculation unit 25 (step A02), and the vehicle acceleration force (Fa) is calculated from the vehicle speed by the acceleration force calculation unit 26 (step A03).
In the shift control device 16, the calculated vehicle acceleration force (Fa) exceeds the acceleration force threshold value (Ta) (Fa> Ta), and the difference between the calculated braking force (Fb) and the calculated vehicle acceleration force (Fa). It is determined whether ( Fa-Fb ) is less than the clutch operation threshold (C1) {( Fa-Fb ) <C1} (step A04).
The acceleration force threshold value Ta is a threshold value (N: SI unit) that can be set at each shift stage 9, and sets an acceleration force of a certain value or more on the downhill road on which the vehicle 1 travels. The clutch operation threshold value C1 is a clutch operation threshold value (N: SI unit) that can be set at each shift stage 9, and is set with a certain safety factor in mind for the deceleration that the drive wheels 15 lock.

Shift control device 16, the vehicle acceleration force of the vehicle 1 traveling on the downhill (Fa) is accelerating force threshold (Ta) or less, and / or the difference of the braking force and (Fb) vehicle acceleration force and (Fa) (Fa When −Fb ) is equal to or higher than the clutch operation threshold (C1) and the determination in (step A04) is NO, the process returns to the calculation of braking force (Fb) (step A02).
In the shift control device 16, the vehicle acceleration force (Fa) of the vehicle 1 traveling on the downhill road exceeds the acceleration force threshold value (Ta), and the difference between the braking force (Fb) and the vehicle acceleration (Fa) ( Fa-Fb). ) Is less than the clutch operation threshold (C1) (t1 in FIG. 3), and if the determination in (step A04) is YES, it is prohibited that the shift stage 4 shifted to the low speed stage side is shifted to the high speed stage side. , The engaged state (clutch position Ct) of the clutch 4 is controlled to the semi-engaged state so that the braking force (Fb) is maintained at a constant braking force target value (Fb1) (after t1 in FIG. 3). A05).
The shift control device 16 prohibits shifting to the high-speed stage side, holds the braking force (Fb) at a constant braking force target value (Fb1) (step A05), and then sets the vehicle acceleration force (Fa) to the acceleration force threshold value. (Ta) or less (Fa ≤ Ta), or the difference ( Fa-Fb ) between the braking force (Fb) and the vehicle acceleration force (Fa) is greater than or equal to the clutch operating threshold (C1) {( Fa-Fb ) ≥ C1} It is determined whether or not there is (step A06).
In the shift control device 16, the vehicle acceleration force (Fa) of the vehicle 1 traveling on the downhill road exceeds the acceleration force threshold value (Ta), and the difference between the braking force (Fb) and the vehicle acceleration force (Fa) ( Fa- ). When Fb ) is less than the clutch operation threshold value (C1) and the determination in (step A06) is NO, the process returns to the control of shifting prohibition of the shift stage 9 and the control of the half-engaged state of the clutch 4 (step A05).
In the shift control device 16, the vehicle acceleration (Fa) of the vehicle 1 traveling on a downhill road is equal to or less than a predetermined value (Ta), or the difference ( Fa-Fb ) between the braking force (Fb) and the vehicle acceleration (Fa) is a clutch. If the operation threshold value (C1) or higher and the determination in (step A06) is YES, the program ends (step A10).

In this way, the shift control device 16 prohibits the shift stage 9 from shifting to the high speed stage side based on the braking force caused by the engine brake and the vehicle acceleration force, and puts the clutch 4 in a semi-engaged state. For control, it is possible to prevent the clutch 4 from being temporarily disengaged by performing a shifting operation during traveling and suddenly changing the braking force due to the engine brake.
Further, since the shift control device 16 controls the engaged state of the clutch 4 so as to keep the braking force caused by the engine brake constant, it is possible to prevent the braking force caused by the engine brake from suddenly changing.
Further, the shift control device 16 prohibits the shift stage 9 from shifting to the high speed stage side on a downhill road, and controls the clutch 4 in a semi-engaged state. Therefore, the shift control device 16 performs a shift operation during traveling to obtain a clutch. It is possible to prevent the braking force of the engine brake from suddenly changing due to the temporary disconnection of 4.

In the speed change control device 16 of the above-described embodiment, the difference ( Fa-Fb ) between the braking force (Fb) and the vehicle acceleration force (Fa) is compared with the clutch operating threshold (C1) {( Fa-Fb ) ≥ C1. }, The shift prohibition of the shift stage 9 and the half-engaged state of the clutch 4 were controlled, but the ratio (Fb / Fa) of the braking force (Fb) to the vehicle acceleration force (Fa) was clutch-operated. It is also possible to compare with the threshold value (C1) {(Fb / Fa) ≧ C1} to control the shift prohibition of the shift stage 9 and the half-engaged state of the clutch 4.
Further, in the shift control device 16 of the above-described embodiment, the clutch control unit 23, the shift stage control unit 24, the braking force calculation unit 25, the acceleration force calculation unit 26, and the downhill road detection unit 27 are controlled as one. Although it is configured in the unit 17, it can be configured by a plurality of control units.
For example, the clutch control unit 23 and the shift stage control unit 24 are composed of a transmission control unit that controls the automatic transmission 4. The braking force calculation unit 25 is composed of an engine control unit that controls the engine 2. The acceleration force calculation unit 26 and the downhill road detection unit 27 are composed of a traveling stability assist control unit that prevents the vehicle 1 from skidding. Then, these transmission control unit, engine control unit, and running stability auxiliary control unit are connected by CAN (Control Area Network) communication, and are configured to transmit and receive information to each other for control.
As a result, even in a shift control device composed of a plurality of control units, it is prohibited that the shift stage 9 is shifted to the high speed stage side based on the braking force caused by the engine brake and the vehicle acceleration force, and the clutch is clutched. By controlling 4 to a semi-engaged state, it is possible to prevent the clutch 4 from being temporarily disengaged by performing a shifting operation during traveling and suddenly changing the braking force due to the engine brake.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to prevent a sudden change in the braking force caused by the engine brake without performing brake control, and an automatic transmission having a clutch for connecting and disconnecting the driving force transmission between the engine and the driving wheels. It can be applied to the shift control device of a transmission.

1 Vehicle 2 Engine 4 Clutch 5 Automatic transmission 8 Clutch actuator 9 Shift stage 11 Shift actuator 12 Final reduction gear train 13 Differential device 15 Drive wheel 16 Shift control device 17 Control unit 18 Engine speed detection unit 19 Vehicle speed detection unit 20 Speed change Stage detection unit 21 Clutch position detection unit 22 Gradient detection unit 23 Clutch control unit 24 Speed change stage control unit 25 Braking force calculation unit 26 Acceleration calculation unit 27 Downhill road detection unit

Claims (3)

A shift control device for an automatic transmission having a clutch that engages and disengages the transmission of driving force between the engine and the drive wheels.
The clutch control unit that controls the engagement and disengagement of the clutch, the shift stage control unit that controls the shift stage of the automatic transmission, and the braking force calculation unit that calculates the braking force caused by the engine brake act on the vehicle. It is equipped with an acceleration force calculation unit that calculates the vehicle acceleration force, which is the force to accelerate .
The vehicle acceleration force calculated by the acceleration force calculation unit exceeds the acceleration force threshold set as an acceleration force of a vehicle above a certain level on a downhill road, and the vehicle acceleration force and the braking force calculated by the acceleration force calculation unit. When the difference from the braking force caused by the engine brake calculated by the calculation unit is less than the clutch operation threshold, which is the clutch operation threshold that can be set at each shift stage, the shift stage control unit has a high speed shift stage. The clutch control unit is characterized in that shifting to the step side is prohibited, and the clutch control unit controls the clutch in a semi-engaged state based on the braking force generated by the engine brake calculated by the braking force calculation unit. Automatic transmission shift control device. The speed change control device for an automatic transmission according to claim 1 , wherein the clutch control unit controls an engaged state of the clutch so as to keep the braking force calculated by the braking force calculation unit constant. .. A downhill road detection unit for detecting that the road surface on which the vehicle travels is a downhill road is provided, and when the downhill road detection unit detects that the downhill road is a downhill road, the speed change control unit has a high speed. prohibited from being shifted to the stage side, the clutch control unit, when it is detected that is downward slope by the downward slope detection unit, and controls the clutch half-engaged state according The shift control device for an automatic transmission according to claim 1 or 2 .

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