JPH10325462A - Gear shift control device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of shift hunting during running on an ascent passage and to effectively work an engine brake during running at a descent passage. SOLUTION: In a surplus drive force calculating means 17, from a difference between a drive force by a speed after up-shift and present running resistance, a surplus drive force after up-shift is calculated, and a difference between a present speed and running resistance, a surplus drive force by the present speed is calculated. In a gear shift permission/prohibition deciding means 17, when a surplus drive force after up-shift during running at an ascent passage is lower than a set value, up-shift is prohibited, a drive force is ensured, and shift hunting during running on an ascent passage is prevented. When a surplus drive force after up shift during running at a descent passage exceeds a set value, up-shift is prohibited, and an engine brake is effectively worked.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission capable of setting an optimal gear position when traveling on an uphill road and traveling on a downhill road.

[0002]

2. Description of the Related Art Generally, the driving force required for a vehicle such as an automobile to travel is not sufficient with the output shaft torque from a torque converter, and the driving force required for traveling on a flat road is increased by a speed reducer. The driving force required for starting, accelerating, climbing a slope, etc. is increased by an automatic transmission connected to the torque converter.

[0003] In a shift control device for controlling the shift of the automatic transmission, a current running condition is determined based on, for example, a vehicle speed and a throttle opening (or an accelerator pedal depression amount) so as to optimize running performance on a flat road. Determine the corresponding gear.

FIG. 5 is a shift diagram showing shift characteristics of a four-speed automatic transmission. The shift characteristics are mapped and stored in the storage device (ROM) of the transmission control unit (TCU). The upshift schedule of the shift speed is indicated by a solid line, and the downshift schedule is indicated by a dashed line. ing.

[0005] As described above, such shift characteristics are set in advance by experiments or the like in order to ensure optimum running on a flat road, and therefore, the uphill road or the engine brake where the driving force is insufficient is required. Not suitable for downhill roads that require

That is, as shown in FIG. 6, when the driver depresses the accelerator pedal, for example, the vehicle is downshifted to the third speed because the driving force is insufficient during traveling on an uphill road at the fourth speed ((a)).
State). Thereafter, when the driver looses the accelerator pedal depression amount because the driving force has a margin in the traveling at the third speed, the transmission control device performs the operation based on the transmission characteristics shown in FIG.
Upshifted (state (b)). At this time, if the driver feels that the driving force is insufficient, the driver again depresses the accelerator pedal, so that the vehicle is downshifted again to the third speed (state (c)).

On the other hand, as shown in FIG. 7, even if the driver releases the accelerator pedal while traveling on a downhill road at the 4th speed, the vehicle speed changes from the 4th speed to the 3rd speed as shown in the shift characteristics of FIG. When the vehicle is traveling on a higher speed side than the downshift line, the vehicle is not downshifted and remains at the 4th speed, or when the accelerator pedal is released while traveling on a downhill road even when traveling at a speed lower than the 3rd speed, If the vehicle speed is higher than the downshift line from 4th speed to 3rd speed, the vehicle is upshifted to 4th speed.

As a result, when the vehicle is traveling on an uphill road, shift hunting frequently occurs due to the operation of the accelerator pedal by the driver, and the traveling stability is impaired. Requires complicated operations such as applying a brake for deceleration and operating the range select lever to downshift to a position where engine braking is effectively generated.

To deal with this, for example, Japanese Patent Publication No. 5-74
No. 748 discloses that a running resistance determined on the basis of a shift speed after an upshift and a vehicle speed is compared with a driving force at a shift speed after an upshift, and when the driving force> the running resistance, the upshift is performed. There is disclosed a technology that permits an upshift when driving force ≦ running resistance.

[0010]

According to the above prior art, even if the accelerator pedal is released during traveling on an uphill road, the upshift is prohibited when the driving force ≦ the traveling resistance.
It is possible to suppress the occurrence of shift hunting.

However, according to this prior art, if the driving force after the upshift slightly exceeds the running resistance,
Upshifting is allowed uniformly, so if the actual running resistance after the upshift exceeds the engine output, the driving force becomes insufficient and the driver can depress the accelerator pedal again to perform the downshift operation again. Shift hunting is likely to occur in a region where the engine output and the running resistance after the upshift are close to each other.

Further, in the above prior art, since the engine output is compared with the running resistance, the upshift is always permitted when the accelerator pedal is released on a downhill road where the engine output> running resistance. The brake cannot be operated effectively, which requires the driver to perform a complicated operation for deceleration.

In view of the above circumstances, the present invention can effectively avoid shift hunting when traveling on an uphill road.
It is an object of the present invention to provide a shift control device for an automatic transmission that can effectively generate an engine brake without requiring a driver to perform a complicated operation on a downhill road.

[0014]

To achieve the above object, a first automatic transmission shift control device according to the present invention comprises:
A driving force setting means for setting a driving force at a shift speed after an upshift based on a driving state of the vehicle; a driving resistance / gradient value setting means for setting a driving resistance and a gradient value based on a driving state of the vehicle; A surplus driving force calculating means for setting a surplus driving force according to a shift speed after an upshift from a difference between the driving force and the running resistance; and the surplus driving force when traveling on an uphill road where the gradient value is larger than a first set value. And a second set value, and when the surplus driving force is smaller than the second set value, a shift permission / prohibition determination means for prohibiting an upshift is provided.

A shift control device for a second automatic transmission sets a driving force according to a current gear position based on a driving condition of a vehicle and sets a driving force according to a gear position after an upshift in the same driving condition. Force setting means, running resistance / gradient value setting means for setting the running resistance and the slope value based on the driving state of the vehicle, and a marginal driving force at the current gear position based on the difference between the current driving force and the running resistance. And a margin driving force calculating means for setting a margin driving force according to the gear stage after the upshift from the difference between the driving force according to the gear stage after the upshift and the running resistance, And comparing the surplus driving force during traveling on an uphill road with a second set value with the surplus driving force,
When the value is smaller than the set value, the upshift is prohibited, and when the margin drive force is smaller than the second set value and the current margin drive force is smaller than the third set value, a shift permission for forcibly downshifting is permitted. / Prohibition determining means.

A shift control device for a third automatic transmission sets a driving force at a current gear position based on a driving condition of a vehicle and sets a driving force at a gear position after an upshift in the same driving condition. Force setting means, running resistance / gradient value setting means for setting the running resistance and the slope value based on the driving state of the vehicle, and a marginal driving force at the current gear position based on the difference between the current driving force and the running resistance. Margin driving force calculating means for setting a margin driving force according to the shift stage after the upshift from the difference between the driving force according to the shift stage after the upshift and the running resistance, and setting the gradient value to a fourth setting. The current margin driving force during traveling on a downhill road smaller than the value is compared with the fifth set value, and the current margin driving force is determined to be equal to or smaller than the fifth margin value.
If it is larger than the set value of
A shift permission / prohibition determining means for prohibiting the upshift when the current margin driving force is smaller than the fifth set value and the margin drive force after the upshift is larger than the sixth set value. Features.

In the first automatic transmission shift control device, the driving force according to the shift stage after the upshift is set based on the driving state of the vehicle, and the running resistance and the gradient value are set based on the driving state of the vehicle. Set. Then, a margin driving force according to the gear position after the upshift is set based on a difference between the driving force and the traveling resistance. When traveling on an uphill road where the gradient value is larger than the first set value, the margin driving force and the second margin are set. When the surplus driving force is smaller than the second setting value, the upshift is prohibited and the driving force is secured.

In the second shift control device for an automatic transmission, the driving force according to the current gear is set based on the driving state of the vehicle, and the driving force according to the gear after the upshift in the same driving state is set. The running resistance and the gradient value are set based on the driving state of the vehicle. Then, a marginal driving force according to the current gear is set based on a difference between the current driving force and the running resistance, and a shift after the upshift is determined based on a difference between the driving force and the running resistance according to the gear after the upshift. When the vehicle is traveling on an uphill road where the gradient value is larger than the first set value, the spare drive force is compared with a second set value, and the spare drive force is set to the second set value. If the value is smaller than the value, the upshift is prohibited, and if the margin driving force is smaller than the second set value and the current margin drive force is smaller than the third set value, the downshift is forcibly performed. Secure power.

In the third shift control device for an automatic transmission, the driving force according to the current gear is set based on the driving state of the vehicle, and the driving force according to the gear after the upshift in the same driving state is set. The running resistance and the gradient value are set based on the driving state of the vehicle. Then, a marginal driving force according to the current gear is set based on a difference between the current driving force and the running resistance, and a shift after the upshift is determined based on a difference between the driving force and the running resistance according to the gear after the upshift. A margin driving force is set by the step, and the current margin driving force when traveling on a downhill road with the gradient value smaller than the fourth setting value is compared with a fifth setting value. When the excess drive force is larger than the set value, the downshift is forcibly performed. When the extra drive force after the upshift is smaller than the fifth set value and the extra drive force after the upshift is larger than the sixth set value, By prohibiting upshifts, the engine brake works effectively.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a system block diagram of the automatic transmission control system. Reference numeral 1 in the figure denotes an engine, and an output shaft 1a of the engine 1 is connected to an automatic transmission 3 via a torque converter 2 which is an example of a starting device, and an output shaft of the automatic transmission 3 is a front wheel shaft or It is connected to a drive shaft (not shown) such as a rear wheel shaft.

The automatic transmission 3 is, for example, a multi-stage transmission using a planetary gear. In the present embodiment, the automatic transmission 3 has at least four forward speeds, and the speeds of the shift clutches and brakes are different. It is appropriately selected according to the engagement / disengagement operation.

The shift control of the automatic transmission 3 is executed by a switching operation of a shift solenoid 4, and the shift solenoid 4 is controlled by a transmission control unit (TCU) 5.

As shown in FIG. 1, the TCU 5 includes a torque converter torque ratio setting unit 11, an acceleration calculation unit 12, a driving force setting unit 13, a running resistance / gradient, and the like. A value setting unit 14, a margin driving force calculation unit 15, a margin driving force target value setting unit 16, a shift permission / prohibition determination unit 17, a normal shift control unit 18, and a shift position determination unit 19 are provided.

In the torque converter torque ratio setting means 11,
The torque ratio ηt is calculated based on the engine speed NE representing the pump speed of the torque converter 2 and the turbine speed NT of the torque converter 2.

That is, first, the speed ratio e is calculated from the ratio between the turbine speed NT and the engine speed NE (e ← NT).
/ NE), the torque ratio ηt of the torque converter 2 is set with reference to a table stored in a ROM (not shown) based on the speed ratio e. In addition, the turbine rotation speed NT
May be calculated based on the vehicle speed and the gear ratio of the gear stage of the automatic transmission 3.

The acceleration calculating means 12 calculates the acceleration A from the variation ΔV of the vehicle speed V per minute time (Δt) (A ← ΔV / Δt). Further, since the calculation cycle Δt is a very short time, the acceleration A can be considered as an acceleration when the throttle opening Th is constant.

The driving force setting means 13 determines the driving force Pn according to the currently selected gear n and the gear n + 1 when upshifting while maintaining the vehicle speed V and the throttle opening Th at this time. The driving force Pn + 1 is set by referring to a map or by calculation.

When the driving forces Pn and Pn + 1 are set by referring to a map, the driving force Pn is set based on the vehicle speed V and the currently selected gear n from the driving force characteristics shown in FIG. Similarly, the same vehicle speed V and the shift speed n + after the upshift
The driving force Pn + 1 is set based on 1.

When the driving forces Pn and Pn + 1 are set by calculation, first, a map is referred to based on the engine speed NE and the throttle opening Th, or the engine output torque Te (m-Kgf) is calculated. Is set (Te ← f
(NE, Te)). And, the engine output torque Te
And the torque ratio ηt, and the currently selected gear n
And the driving force Pn (Kg
Set f). Pn ← κ · Te · in · ηt where κ is a fixed value (κ ← ij / r) obtained from the reduction ratio ij of the reduction gear and the effective radius r of the driving wheels. The driving force Pn
+1 (Kgf) is calculated from Pn + 1 ← κ · Te · in + 1 · ηt. Here, in + 1 is the speed ratio of the shift speed n after the upshift.

The running resistance / gradient value setting means 14 calculates the running resistance R and the slope value D. The running resistance R is calculated from the sum of the rolling resistance Rr, the air resistance Ra, and the gradient resistance Rd (R ← Rr + Ra + Rd).

That is, the rolling resistance Rr is calculated from Rr ← μr · W. Here, W is the vehicle weight (Kg), and μr is a rolling resistance coefficient determined by the road surface.

The air resistance Ra is calculated from Ra ← μa · S · V ² . Here, μa is the air resistance coefficient determined by the shape of the vehicle, and S is the front projected area (m ² ) of the vehicle.

The gradient resistance Rd is calculated from the following equation of motion. Rd ← P− (Wa + Rr + Ra) Here, Wa is an acceleration resistance as an inertial force generated by acceleration and deceleration of the vehicle, and is calculated based on the acceleration A, Wa ← W · A / g, where g: gravity acceleration.

When an acceleration sensor is provided in the vehicle, the acceleration sensor detects Am which is the sum of the acceleration A of the vehicle and the inclination angle component of the gravitational acceleration. Rd ← W · (Am-A) In this case, the gradient angle θ when climbing a hill is (+), and the gradient angle θ when descending a hill is (−).

The gradient value D is calculated from the following equation using the gradient resistance Rd: D ← Rd / W.

The surplus driving force calculating means 15 calculates the surplus driving force Un at the currently selected gear n and the surplus driving force Un + 1 at the speed n + 1 after the upshift.

Since the marginal driving force Un at the currently selected gear n is the difference between the driving force Pn at this time and the running resistance R, it is calculated from Un ← Pn-R, and the upshift is performed. The margin driving force Un + 1 at the subsequent shift speed n + 1 is calculated from Un + 1 ← Pn + 1-R.

The spare driving force target value setting means 16 compares the set values Ua, Ub, Uc, Ud, which are comparison reference values for the spare driving forces Un, Un + 1, with the gradient value D, vehicle speed V, throttle opening. It is set by calculation or referring to a map based on a parameter indicating a running state such as Th.

The shift permission / prohibition determination means 17 reads the gradient value D, and the gradient value D is larger than the first set value, that is, the gradient determination value Ds (where Ds> 0). Alternatively, when the vehicle is traveling on a downhill road where the gradient value D is equal to or lower than the downhill determination value Dd (where Dd <0), which is the fourth set value, the margin driving forces Un and Un + 1 are read. Based on the driving forces Un and Un + 1, it is determined whether to permit an upshift or to forcibly downshift. The shift permission / prohibition determination process is executed in a shift permission / prohibition determination routine described later.

The normal shift control means 18 sets an optimum shift stage during the current running according to the shift characteristics shown in FIG. 5 based on the throttle opening Th and the vehicle speed V.

In the shift position determining means 19, when the gear position set by the normal gear speed control means 18 is in the upshift direction with respect to the current gear position, the gear change permission / shift is determined.
The prohibition determination means 17 determines whether or not upshifting is permitted. If the upshifting is permitted, upshifting to the set gear position is performed, and if upshifting is prohibited, the current gear position is maintained. I do. Further, when the vehicle is traveling on a downhill road where the gradient value D is smaller than the set value Dd, and when a shift down command is output from the shift permission / prohibition determination unit 17, the command is set by the normal shift control unit 18. Even if the changed gear position maintains the current gear position,
Set the gear position after downshift.

The drive signal corresponding to the gear determined by the shift position determining means 19 is transmitted to the shift solenoid 4.
And the gear position of the automatic transmission 3 is set according to the running state of the vehicle.

The shift permission / inhibition determination routine executed by the shift permission / inhibition determination means 17 will be described in detail with reference to the flowchart shown in FIG.

First, in step S1, the gradient value D is compared with the uphill-side determination value Ds (Ds> 0), and D> D
If the vehicle is traveling on an uphill road having a larger slope angle than the uphill determination value Ds of s, the process proceeds to step S2, and if D ≦ Ds,
Proceed to step S3.

When the process proceeds to step S2, the marginal driving force Un + 1 after the upshift is compared with the set value Ua, which is the second set value, and in the gear after the upshift, Un + 1> Ua. If it is determined that there is enough driving force, the process proceeds to step S4 to permit the upshift and exit the routine.

If it is determined in step S2 that the driving force is insufficient at the speed after the upshift of Un + 1 ≦ Ua, the process proceeds to step S5, where the upshift is prohibited. Is compared with the set value Ub which is the third set value, and when it is determined that the drive force has an allowance at the current gear position where Un ≧ Ub, the routine exits as it is.

As a result, for example, when the driver feels insufficient driving force while driving on an uphill road at the fourth speed and the driver depresses the accelerator pedal, the gear is downshifted to the third speed.
Even if an attempt is made to upshift in accordance with the shift characteristics shown in FIG. 5 due to the increase in the vehicle speed V, if it is determined that the driving force is insufficient at the shift stage (fourth speed) after the upshift,
Since the upshift is prohibited (step S4), shift hunting caused by insufficient driving force after the upshift is prevented beforehand, and good drivability can be obtained.

The set value Ua is a variable value set in accordance with the running conditions. For example, the set value Ua is calculated or mapped based on parameters indicating the running state such as the gradient value D, the vehicle speed V, the throttle opening Th and the like. Set by reference. By setting the set value Ua as a variable value, it is possible to more accurately determine the driving force shortage after the shift, and it is possible to set the gear position most suitable for the uphill traveling condition.

On the other hand, when it is determined in step S6 that the driving force is insufficient at the current gear position where Un <Ub,
Proceed to step S7 to forcibly downshift and exit the routine.

As a result, when the marginal driving force Un at the current gear is less than the set value Ub, the current gear is forcibly set even if the current gear is determined by the shift characteristics shown in FIG. By downshifting, the driving force is compensated before the driving force shortage actually occurs, so that good driving performance can be obtained.

The set value Ub is a variable value set in accordance with the running conditions. For example, the set value Ub is calculated or mapped based on parameters indicating the running state such as the gradient value D, the vehicle speed V, the throttle opening Th and the like. Set by reference. By setting the set value Ub to a variable value, the downshift timing of the shift speed can be optimized.

On the other hand, when it is determined in step S1 that D.ltoreq.Ds and the process proceeds to step S3, the gradient value D is compared with the downhill determination value Dd (where Dd <0). And
If D ≧ Dd, that is, if the traveling road has a relatively small gradient angle of Ds ≦ D ≦ Dd, the process returns to step S1, and D <D
If the vehicle is traveling on a downhill road having a greater gradient angle than the descent-side determination value Dd of d, the process proceeds to step S8, where the current marginal driving force Un is compared with a fifth set value Uc, and Un> Uc.
If there is a margin in the current driving force, the process proceeds to step S7 to forcibly downshift and exit the routine.

When the current driving force has a margin when traveling downhill, that is, when the acceleration A increases, the engine brake is insufficient. Therefore, the engine brake is effectively operated by forcibly downshifting. Can be.

On the other hand, if it is determined in step S8 that the driving force is insufficient at the current gear stage of Un ≦ Uc, the process proceeds to step S10, where the marginal driving force Un after the upshift and the sixth set value are used. It is compared with a certain set value Ud to determine whether or not there is a margin in the driving force at the shift speed after the upshift. If there is no margin in the driving force at the speed after the upshift of Un + 1 ≦ Ud, the routine exits from the routine.

The set value Uc is a variable value set in accordance with the running conditions. For example, the set value Uc is calculated or mapped based on parameters indicating the running state such as the gradient value D, the vehicle speed V, the throttle opening Th and the like. Set by reference. By making the set value Uc a variable value, it is possible to run at the gear position most suitable for the running conditions.

If the driving force has a margin at the speed after the upshift of Un + 1> Ud, the process proceeds to step S9, and
Prohibit the upshift and exit the routine.

Since the marginal driving force Un + 1 after the upshift when traveling on a downhill road is proportional to the acceleration A, Un + 1> U
In the case of c, the upshift is prohibited, thereby preventing the acceleration A from increasing.

The set value Ud is a variable value set according to the running conditions, and is calculated or mapped based on parameters indicating the running state, such as the gradient value D, the vehicle speed V, the throttle opening Th, and the like. Set by reference. By making this set value Ud a variable value, even when traveling downhill,
It is possible to travel at the most suitable gear for the traveling conditions.

[0059]

According to the first aspect of the present invention, even if the automatic transmission attempts to upshift when traveling uphill, a margin drive set based on the difference between the driving force after the upshift and the current traveling resistance. When the force is smaller than the set value, the upshift is prohibited, so that the driving force shortage due to the upshift and the shift hunting can be effectively avoided.

According to the second aspect of the invention, in addition to the effect of the first aspect, the marginal driving force set from the difference between the current driving force and the running resistance when the upshift is prohibited is smaller than the set value. In some cases, the downshift is forcibly performed before the driving force shortage actually occurs, so that the driving force shortage during traveling can be avoided.

According to the third aspect of the invention, even if the automatic transmission attempts to upshift during downhill traveling, a margin driving force set based on the difference between the driving force after the upshift and the current traveling resistance. When is larger than the set value, the upshift is prohibited, so that an increase in acceleration due to the upshift is avoided, the engine brake can be effectively operated, and the driver is manually downshifted or braked. Good drivability can be obtained without requiring a complicated operation such as frequent depression of the pedal.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an automatic transmission control device.

FIG. 2 is a system block diagram of an automatic transmission control system.

FIG. 3 is a flowchart showing a shift permission / prohibition determination routine;

FIG. 4 is a conceptual diagram of a table showing driving force characteristics corresponding to a vehicle speed and a gear position.

FIG. 5 is a conceptual diagram of a map showing shift control characteristics set based on a vehicle speed and a throttle opening.

FIG. 6 is an explanatory view showing a conventional shift control during traveling on an uphill road.

FIG. 7 is an explanatory view showing a conventional shift control during downhill traveling.

[Explanation of symbols]

 13: Driving force setting means 14: Running resistance / gradient value setting means 15: Margin driving force calculating means 17: Shift permission / prohibition determining means D: Gradient value Dd: Fourth set value Ds: First set value n: (Current) shift speed n + 1... (After upshift) shift speed P... (Current) drive force Pn + 1... (After upshift) drive force R... Running resistance Ua... Second set value Ub. Set value 3 Uc: Fifth set value Ud: Sixth set value Un, Un + 1 ... Extra driving force

Claims (3)

[Claims] 1. A driving force setting means for setting a driving force at a shift speed after an upshift based on a driving state of a vehicle, and a driving resistance and a gradient value for setting a driving resistance and a gradient value based on a driving state of the vehicle. Setting means; surplus driving force calculating means for setting a surplus driving force according to the gear position after an upshift from the difference between the driving force and the running resistance; and when traveling on an uphill road, wherein the gradient value is larger than a first set value. A shift permission / prohibition determining means for comparing the surplus driving force with a second set value and prohibiting an upshift when the surplus driving force is smaller than the second set value. Transmission control device for automatic transmission. 2. A driving force setting means for setting a driving force at a current gear position based on a driving condition of a vehicle and for setting a driving force at a gear position after an upshift in the same driving condition. Running resistance / gradient value setting means for setting a running resistance and a gradient value based on the current driving speed and a running speed based on a difference between the current driving force and the running resistance. Margin driving force calculating means for setting a margin driving force according to the gear position after an upshift from the difference between the driving force and the running resistance, and the margin when traveling on an uphill road where the gradient value is larger than a first set value. The driving force is compared with a second set value. If the surplus driving force is smaller than the second set value, the upshift is prohibited, and if the surplus driving force is smaller than the second set value and the current Extra Driving force transmission control apparatus for an automatic transmission, characterized in that it comprises a transmission permission / inhibition determination unit forcibly downshift is smaller than the third set value. 3. A driving force setting means for setting a driving force at a current gear position based on a driving condition of the vehicle and for setting a driving force at a gear position after an upshift in the same driving condition. Running resistance / gradient value setting means for setting a running resistance and a gradient value based on the current driving speed and a running speed based on a difference between the current driving force and the running resistance. Margin driving force calculating means for setting a margin driving force for the gear position after an upshift from the difference between the driving force and the traveling resistance according to the following formula: The surplus driving force is compared with the fifth set value, and if the current surplus driving force is larger than the fifth set value, the downshift is forcibly performed. Small and Shift control device for an automatic transmission, characterized in that when excess driving force after the upshift is larger than the set value of the sixth and a transmission permission / inhibition determination unit that prohibits upshift.