JPH0674321A - Speed change control device for automatic transmission - Google Patents

Abstract

PURPOSE:To ensure stability of vehicle action at acceleration turning time by providing a speed change control means for determining speed change ratio so that an estimated cornering force corresponding value by the speed change ratio, where a speed change is intended, is prevented from decreasing lower than a detection cornering force corresponding value. CONSTITUTION:In an AT controller 7 for fetching each output signal of a wheel load sensor 8, throttle opening sensor 9, car speed sensor 10 and a cross acceleration sensor 11, first based on a car speed and a throttle opening, a gear position is set to calculate drive force estimated in this gear position. Next, a cornering force cross acceleration conversion value in this drive force is calculated by using a cross acceleration conversion value map from the drive force and a wheel load, to judge whether or not this cross acceleration conversion value is an actual cross acceleration or more. At the time of acceleration turning by step-on operation of an accelerator, a downshift is inhibited to prevent cornering force form decreasing, so that the cross acceleration value is prevented from decreasing lower than the actual cross acceleration.

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.

[0002]

2. Description of the Related Art Conventionally, as a shift control device for an automatic transmission, for example, one disclosed in JP-A-59-231249 is known.

In the above-mentioned conventional publication, the shift point of the shift schedule is shifted to the high speed side in response to the signal from the cornering detection means during cornering of the vehicle, and the automatic transmission shifts up when the accelerator pedal is released during turning. A technique for preventing the deterioration of drivability and riding comfort is disclosed.

[0004]

However, in the above-mentioned conventional technique, although the cornering performance of the vehicle is improved by prohibiting the foot-up-shift during turning, the accelerator is greatly depressed to the kick-down area during cornering of the vehicle. There is a problem that the cornering force is reduced due to an increase in the driving force transmitted to the drive wheels due to the downshift, and the driving feeling during turning is deteriorated.

That is, the force (braking / driving force + cornering force) that the tire allows during turning has a limit due to the tread pattern of the tire, the road friction coefficient, and the like. Therefore, when one driving force increases in the tire allowable power limit state, the other cornering force decreases and the total allowable value is maintained.

As a result, when the cornering force of the drive wheels is reduced in the rear-wheel drive vehicle, the rear wheels tend to slide outward in the turning direction, and when the cornering force of the drive wheels is reduced in the front-wheel drive vehicle. , The front wheels tend to slide outward in the turn.

The present invention has been made in view of the above problems, and it is an object of the present invention to maintain the stability of the vehicle behavior during acceleration and turning in a shift control device for an automatic transmission.

[0008]

In order to solve the above problems, in the shift control device for an automatic transmission according to the present invention, the predicted cornering force equivalent value depending on the gear ratio to be changed is
A gear shift control means is provided for determining the gear ratio so as not to fall below a value equivalent to the detected cornering force.

That is, as shown in the claim correspondence diagram of FIG. 1, the cornering force equivalent value detecting means a for detecting the cornering force equivalent value received by the tire at the time of turning, and the gear ratio to be changed before the gear change. A driving force predicting means b for calculating the driving force in the above, and a cornering force equivalent value predicting means c for predicting a cornering force equivalent value of the tire after shifting by using the driving force predicted by the driving force predicting means b as one input. And a shift control means d for determining a gear ratio so that the predicted cornering force equivalent value does not become equal to or less than the detected cornering force equivalent value.

[0010]

When turning, the cornering force equivalent value detecting means a detects the cornering force equivalent value received by the tire.

On the other hand, the driving force predicting means b calculates the driving force at the gear ratio to be changed before shifting, and the cornering force equivalent value predicting means c is calculated.
At, the driving force predicted by the driving force prediction means b is used as one of the inputs to predict the cornering force equivalent value of the tire after shifting.

Then, in the shift control means d, the gear ratio is determined so that the predicted cornering force equivalent value does not fall below the detected cornering force equivalent value.

For example, when a vehicle equipped with an automatic transmission having multiple gear positions undergoes an acceleration turn, when a downshift is performed in the search of a shift pattern by depressing the accelerator, the following shiftdown is performed prior to execution of the downshift. The predicted cornering force equivalent value at the downshift gear position of is calculated, and if the predicted cornering force equivalent value is less than or equal to the detected cornering force equivalent value at that time, the downshift is prohibited. By prohibiting the downshifting while monitoring the predicted value and the actual value of the cornering force, it is possible to suppress the decrease in the cornering force that makes the vehicle behavior unstable during the acceleration turn.

When the automatic transmission is a continuously variable transmission, instead of prohibiting downshifting in which the gear ratio is not changed, the gear ratio is determined so as to maintain a constant cornering force during an acceleration turn, and the downshift is performed. In addition, shift up can be performed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

First, the structure will be described.

FIG. 2 is a diagram of an electronically controlled automatic transmission system of a vehicle to which the automatic transmission transmission control device of the embodiment of the present invention is applied.

In FIG. 2, 1 is an engine, 2 is a torque converter, 3 is a transmission having a fourth speed gear, 4 is a control valve unit, 5 and 6 are shift solenoids, and 7 is an A / T controller.

The A / T controller 7 inputs sensor signals from a wheel load sensor 8, a throttle opening sensor 9, a vehicle speed sensor 10, a lateral acceleration sensor 11 (corresponding to a cornering force equivalent value detecting means), The gear position is determined based on these signals and the shift control speed described later, and signals for obtaining the determined gear position are provided to the shift solenoids 5, 6
Output to.

Next, the operation will be described.

(A) Shift control processing operation FIG. 3 is a flow chart showing the flow of shift control processing operation performed by the A / T controller 7. Each step will be described below.

In step 101, the wheel load W from the wheel load sensor 8, the throttle opening TVO from the throttle opening sensor 9, the vehicle speed VSP (transmission output shaft speed) from the vehicle speed sensor 10, and the lateral acceleration YG from the lateral acceleration sensor 11 are obtained. Is read.

In step 102, the next gear position NEXTG _Pt is set by searching which gear position the vehicle speed VSP and throttle opening TVO read in step 101 belong to in the shift pattern shown in FIG. To be done.

In step 103, the driving force F at the next gear position NEXTG _Pt set in step 102 is calculated as follows (corresponding to driving force predicting means).

First, assuming that the turbine speed is N _t , N _t = K · VSP / i _G (K is a constant, i _G is a transmission gear ratio), and the turbine torque T _t is the turbine speed N _t. And throttle opening TVO and the turbine torque map shown in FIG.

T _t = f ₁ (N _t , TVO) Therefore, the driving force F is F = i _G · i _F · T _t = i _G · i _F · f ₁ (N _t , TVO). Here, i _F is the final reduction ratio.

In step 104, the cornering force lateral acceleration conversion value YG _CF in the driving force F calculated in step 103 is calculated as follows (corresponding to cornering force equivalent value predicting means).

That is, the cornering force lateral acceleration conversion value YG _CF is obtained by the driving force F, the wheel load W and the lateral acceleration conversion value map shown in FIG. 6, and is expressed by the formula: YG _CF = f ₂ (F, W ).

In step 105, it is determined whether the cornering force lateral acceleration conversion value YG _CF is greater than or equal to the lateral acceleration YG.

At step 106, the next gear position NEXTG
_Pt is set as it is as the command gear position NextG _P.

[0031] At step 107, a shift command from A / T controller 7 as the set commanded gear position NextG _P is obtained in the shift solenoids 5,6 is outputted.

In step 108, the next gear position NEXTG
_Pt is the next gear position set in step 102 NEXTG _Pt
The gear position is set by adding 1.

In step 109, the next gear position NEXTG _Pt set in step 108 is the current gear position CUR.
It is determined whether it is equal to G _P.

(B) When traveling straight ahead When traveling straight ahead, the cornering force lateral acceleration conversion value YG _CF and lateral acceleration YG both become zero, so that the condition of step 105 is satisfied, and step 101 → step 1
02 → step 103 → step 104 → step 10
The flow proceeds from 5 to step 106 to step 107, and in step 102 normal shift control is performed to obtain the gear position determined by the shift schedule of FIG.

Therefore, upshifting and downshifting are performed so that the optimum gear position can be obtained according to changes in the vehicle speed VSP and the throttle opening TVO. The characteristics of this shift control are determined by setting the shift schedule according to the purpose, such as the emphasis on fuel consumption and the emphasis on running performance.

(C) Accelerating turn During the acceleration turn while depressing the accelerator, as shown in FIG.
According to the shift pattern shown in (4), a case of performing a 4 → 3 downshift and a case of performing a 4 → 2 downshift will be described.

During acceleration turning while depressing the accelerator, when the gear position by the vehicle speed VSP and the throttle opening TVO changes from the fourth speed position to the third speed position on the shift pattern as shown in FIG. It is assumed that the cornering force lateral acceleration conversion value YG _CF predicted at 104 has reached the 3rd position on the lateral acceleration conversion value map shown in FIG.

At this time, as is apparent from FIG. 6, since the cornering force lateral acceleration conversion value YG _CF is equal to or greater than the current lateral acceleration YG, the condition of step 105 is satisfied, and step 101 → step 102 → step 10
3 → step 104 → step 105 → step 106
→ The flow proceeds to step 107, and step 106
Then, the next gear position NEXTG _Pt (3rd speed) will be set as it is as the command gear position NEXTG _P (3rd speed),
Similarly to the normal shift control, the downshift from the fourth speed to the third speed is executed.

If the gear position due to the vehicle speed VSP and the throttle opening TVO is changed from the 4th speed position to the 2nd speed position on the shift pattern during acceleration turn while depressing the accelerator pedal, as shown in FIG. It is assumed that the cornering force lateral acceleration conversion value YG _CF predicted at 104 has reached the 2nd position on the lateral acceleration conversion value map shown in FIG.

At this time, as is apparent from FIG. 6, since the cornering force lateral acceleration conversion value YG _CF is equal to or less than the current lateral acceleration YG, the condition of step 105 is not satisfied, and step 101 → step 102 → step 1
03 → step 104 → step 105 → step 10
8 → step 109 → step 106 → step 107
In step 108, the third gear position NEXTG _Pt (second gear) on the shift map, which is 1 is added to the third gear position, is set as the next gear position NEXTG _Pt, and in step 109,
Next gear position NEXTG _Pt (3 set in step 108)
(Speed) is not equal to the current gear position CURG _P (4th speed), the routine proceeds to step 106, where the next gear position NEXTG _Pt (3rd speed) set at step 108 is the command gear position NE.
It is set as XTG _P (third speed), instead of downshifting to the original 4 gear to second gear, so that the downshift from 4th speed to 3rd speed is executed.

As described above, during the acceleration turn in which the driving force F increases due to the accelerator depression operation, the cornering force lateral acceleration conversion value Y at the gear position to be changed next is obtained.
Predict G _CF, by cornering force lateral acceleration corresponding value YG _CF due to the prediction so as not to less than or equal to the current lateral acceleration YG, when the above example is to prohibit downshifting 4th speed → 2 speed, A decrease in cornering force due to an increase in driving force F is prevented. As a result, a sudden change in vehicle behavior such as a tendency of the rear wheel side to easily slide to the outside of turning in the case of a rear wheel drive vehicle and a tendency of the front wheel side to easily slide to the outside of turning in the case of a front wheel drive vehicle can be suppressed.

Incidentally, in the case of 4 → 3 downshifting according to the shift pattern shown in FIG. 4, when the cornering force lateral acceleration conversion value YG _CF predicted at the third speed position exceeds the current lateral acceleration YG, The 4 → 3 downshift is prohibited, and the fourth gear position is maintained.

Next, the effect will be described.

(1) Predict the cornering force lateral acceleration conversion value YG _CF depending on the gear position to be changed according to the gear change pattern during turning, and the cornering force lateral acceleration conversion value YG _CF becomes equal to or smaller than the current lateral acceleration YG. In that case, the downshift is prohibited, and YG _CF ≧ YG
Since it is a device that performs gear shift control that allows only gear shifts that maintain the vehicle's speed, sudden changes in vehicle behavior due to a decrease in cornering force that accompanies an increase in driving force due to gear shifting during acceleration and turning are suppressed, and stability of vehicle behavior is maintained. be able to.

(2) In the case of performing a downshift of one or two steps by sudden depression of the accelerator during an accelerated turn,
When YG _CF ≧ YG is not satisfied, the downshift is prohibited, but the downshift from the downshift position on the shift pattern to the position one step higher is permitted, so that YG _CF ≧ YG is satisfied. As compared with the case where all downshifts are prohibited when not in use, it is possible to realize turning traveling in which the driver's intention to accelerate is reflected.

Although the embodiments have been described above with reference to the drawings, the specific configuration is not limited to the embodiments, and modifications and additions within the scope of the present invention are included in the present invention. Be done.

For example, in the embodiment, the example in which the invention is applied to the automatic transmission having multiple speeds is shown, but the invention may be applied to a continuously variable automatic transmission. In this case, YG _CF ≧
When YG is not satisfied, the gear ratio to be changed next is corrected to a gear ratio that satisfies YG _CF ≧ YG, and a downshift is executed, so that fine control that achieves good balance between turning stability and turning acceleration. Is possible.

In the embodiment, the cornering force lateral acceleration conversion value is used as the cornering force equivalent value. However, the cornering force itself may be calculated, or the side force of a tire that substantially matches the cornering force. May be used as the cornering force equivalent value.

[0049]

As described above, according to the present invention, in the shift control device for an automatic transmission, the predicted cornering force equivalent value depending on the gear ratio to be shifted is:
Since the shift control means for determining the shift ratio so as not to become equal to or less than the detected cornering force equivalent value is provided, it is possible to obtain the effect that the stability of the vehicle behavior can be maintained during an accelerated turn.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims showing a shift control device for an automatic transmission according to the present invention.

FIG. 2 is a diagram of an electronically controlled automatic transmission system of a vehicle to which a shift control device for an automatic transmission according to an embodiment is applied.

FIG. 3 is a flowchart showing a flow of a shift control processing operation performed by the A / T controller of the embodiment.

FIG. 4 is a diagram showing an example of a shift pattern set in the A / T controller of the embodiment.

FIG. 5 is a turbine torque map set in the A / T controller of the embodiment.

FIG. 6 is a map of converted cornering force lateral acceleration values set in the A / T controller of the embodiment.

FIG. 7 is an operation explanatory view showing a change in throttle opening degree on a shift pattern at the time of acceleration turning in the embodiment apparatus.

[Description of Reference Signs] a Cornering Force Equivalent Value Detecting Means b Driving Force Predicting Means c Cornering Force Equivalent Predicting Means d Shift Control Means

Claims (1)

[Claims] 1. A cornering force equivalent value detecting means for detecting a cornering force equivalent value received by a tire during turning, and a driving force predicting means for calculating a driving force at a gear ratio to be changed before shifting. Cornering force equivalent value predicting means for predicting the cornering force equivalent value of the tire after shifting with the driving force predicted by the driving force prediction means as one of the inputs, and the predicted cornering force equivalent value is the detected cornering force equivalent value. A shift control device for an automatic transmission, comprising: a shift control means for determining a gear ratio so as not to be below.