JPH07305766A - Gear shift control device for automatic transmission for vehicle - Google Patents

Abstract

PURPOSE:To improve operability on a descending slope by providing a gear shift demand signal selecting means to output a gear shift demand signal based on driver operation to a gear shift control device prior to a gear shift demand signal based on the state of a vehicle during descent of a slope. CONSTITUTION:A gear shift control device for an automatic transmission for a vehicle comprises a vehicle gear shift demand signal generating means A to generate a gear shift demand signal based on a vehicle state during descent of a slope; a driver gear shift demand signal generating signal B to generate a gear shift demand signal based on operation of a driver; and a gear shift demand signal selecting means C to give priority to a gear shift demand signal based on operation of a driver. When a gear shift demand based on operation of a driver is effected, control of a descending slope based on a running state, for example, according to a gradient and vehicle acceleration is prohibited, Meanwhile, when a gear shift demand based on operator operation is not effected, control of descending slope based on a running state is effected. This constitution improves operability on a descending slope without causing a driver to feel a sensation of a physical disorder.

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 with a torque converter for a vehicle, and more particularly to an improvement in shift control during downhill driving.

[0002]

2. Description of the Related Art In general, an automatic transmission with a torque converter for a vehicle equipped with an internal combustion engine is adapted to automatically shift gears based on a preset shift pattern according to the running state of the vehicle. . That is, the shift pattern for setting the shift speed according to the vehicle speed and the engine load (for example, throttle opening) is stored in the storage means of the control unit, and the shift is controlled according to this shift pattern. In addition,
Normally, the shift pattern is set such that, as long as the vehicle speed is the same, the smaller the engine load is, the higher the shift is likely to be.

[0003]

However, in such a conventional automatic shift control device, for example, when a vehicle is descending a hill, the throttle opening is upshifted in response to a driver's deceleration request in which the throttle opening is fully closed. There is a tendency for the driver to feel a sense of incongruity against the deceleration request, and because the deceleration effect due to the engine brake is not exerted, the vehicle drivability is deteriorated and the foot brake is overloaded.

In order to solve such a problem at the time of downhill, for example, as disclosed in Japanese Patent Publication No. 4-4351, the torque generated by the engine is calculated based on the throttle opening and the engine speed. Calculating the vehicle running resistance based on the calculated generated torque, the vehicle acceleration, and the vehicle weight,
It has been proposed to compare the vehicle running resistance with a preset value according to the shift speed, and perform shift control to an optimum shift speed so that a desired acceleration can be obtained on a downhill. .

However, in this case, if the vehicle running resistance is equal to or lower than a predetermined value, it is determined that the vehicle is on a downhill road, and the gear stage at which a predetermined acceleration can be obtained is automatically selected. There is a problem in that the driver's downshift request (depressing the throttle) for overtaking cannot be reflected in the shift control. The present invention has been made in view of such a conventional problem, and optimizes the shift control on the downhill road by reflecting the shift request of the driver, thereby improving the vehicle drivability on the downhill road. An object of the present invention is to provide a shift control device for an automatic transmission for a vehicle, which is capable of performing the above. Moreover, it aims at making the said control more highly accurate.

[0006]

Therefore, according to the invention described in claim 1, as shown in FIG. 1, in a shift control device of an automatic transmission for performing shift control based on a shift request signal, when a downhill In the vehicle downshift request signal generating means A for generating a shift request signal based on the state of the vehicle, the driver shift request signal generating means B for generating a shift request signal based on the driver's operation, The shift request signal selecting unit C prioritizes the shift request signal based on the driver's operation with respect to the shift request signal based on the state of the vehicle and sends the shift request signal to the shift control device.

According to the second aspect of the invention, the shift request signal based on the state of the vehicle is a shift request signal for maintaining the vehicle acceleration at a predetermined value. According to the third aspect of the invention, the shift request signal based on the driver's operation is a downshift request signal based on the driver's throttle operation.

[0008]

In the invention according to claim 1 having such a configuration, when the shift control on the downhill road is performed, the shift request based on the driver's operation is prioritized over the shift request based on the running state of the vehicle. To As a result, when there is a shift request based on the driver's operation, the downhill road control based on the running state of the vehicle (for example, according to the gradient, the vehicle acceleration, etc.) is prohibited while the driver's operation is performed. When there is no shift request, downhill control is performed based on the running state of the vehicle, so that the vehicle drivability on the downhill can be improved without causing the driver to feel uncomfortable.

According to the second aspect of the present invention, the shift request based on the running state of the vehicle when performing the shift control on the downhill road is the shift request for maintaining the vehicle acceleration at a predetermined value. With this, when there is no driver's shift request,
Since it is possible to prevent the vehicle from decelerating or accelerating too much on the downhill road, it is possible to obtain better vehicle drivability on the downhill road without causing the driver to feel uncomfortable.

According to the third aspect of the invention, when performing the shift control on the downhill road, a downshift request (for example, an overtaking acceleration request) is performed by a throttle operation that most directly, accurately and promptly responds to the driver's intention. When there is such a request, the downhill shift control based on the running state of the vehicle is prohibited, while when there is no downshift request based on the driver's intention, the downhill shift control based on the running state of the vehicle is prohibited. Therefore, it is possible to improve the accuracy of the control, and thereby to obtain a good vehicle drivability on a downhill road that does not cause the driver to feel uncomfortable.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 2, the engine 1 is connected to the automatic transmission 2 so that the generated torque is transmitted to vehicle drive wheels (not shown). The automatic transmission 2 includes a torque converter 3 for inputting the torque generated by the engine 1 through a fluid.
And a multi-stage speed change gear mechanism 4 for inputting the output of the torque converter 3 and changing and outputting the same, and a hydraulic mechanism (not shown) for driving these.

The hydraulic mechanism of the speed change gear mechanism 4 incorporates solenoid valves 6A and 6B,
By switching the combination of opening and closing of the solenoid valves 6A and 6B, the combination of engagement and disengagement of each clutch included in the speed change gear mechanism 4 is switched, and a shift to a desired shift speed is performed. . ON / OFF control of the solenoid valves 6A, 6B is performed by the CPU, R
This is performed based on a control signal from a control unit 50 including an OM, a RAM, an A / D converter, an input / output interface and the like.

Signals from various sensors are input to the control unit 50. As various sensors, there are provided a throttle sensor 7 that outputs an output signal according to the throttle opening TVO, and a vehicle speed sensor 8 that detects the vehicle speed VSP by detecting the rotation speed of the output shaft (output shaft 5) of the automatic transmission 2. Has been. Below, a control unit 50 having a function as shift request signal selecting means according to the present invention.
3 and 4 for the shift control on the downhill road performed by
It will be described according to the flowchart shown in FIG.

Step 1 (indicated as S1 in the figure).
The same applies hereinafter. ), Vehicle speed VSP and throttle opening TV
Read O. In step 2, it is determined from the driver's throttle depression amount (throttle opening TVO) whether or not there is a downshift request based on the normal shift pattern (FIG. 5).
See the dashed line). If there is a downshift request (for example, when the throttle opening TVO increases at the same vehicle speed), this flow is ended as it is, and the downshift is performed according to the shift pattern (Fig. 5) in the normal running. If there is no downshift request, go to step 3.

The step 2 constitutes a driver shift request signal generating means according to the present invention. In step 3, the current acceleration resistance (RESI-A) is calculated. The current acceleration resistance (RESI-A) can be calculated by the following formula. RESI-A = ALF x k α ALF; current acceleration, k α; constant for acceleration resistance calculation (set by vehicle weight etc.) In step 4, vehicle speed VSP and R / L table (air resistance + rolling resistance calculation table, (See Fig. 6)
Calculate SI-RL (air resistance + rolling resistance).

In step 5, the present turbine rotation speed (Nt, that is, the output shaft rotation speed of the torque converter 3) is obtained. The turbine rotation speed (Nt) can be calculated by the following formula. Nt = VSP × k Nt (g) k Nt (g); a constant determined from the current shift stage, g = current shift stage Note that the current shift stage is the gear position at which the shift gear mechanism 4 detects the shift stage position. The sensor 9 may be provided for detection, but it is advantageous in terms of cost to make the determination from the current shift instruction signal of the control unit 50 or the like.

In step 6, the current turbine torque (Tt, that is, the output shaft torque of the torque converter 3) is obtained from the vehicle speed VSP and the turbine torque Tt map (see FIG. 7, three-dimensional map of Nt, TVO and Tt). In step 7, the present driving force (FCE) is obtained from the following formula. FCE = Tt × k Tt (g) k Tt (g); a constant determined from the current shift speed, g = current shift speed In step 8, the running resistance (RESI-I) is obtained from the following equation.

RESI-I = (FCE)-(RESI-RL)-(RESI-A) In step 9, vehicle speed VSP and TRA table (TGT-RA).
The calculation table, TGT-RA, calculates the TGT-RA from the "downshift target acceleration" (see FIG. 8). It should be noted that the “downshift target acceleration” is preferably set to an acceleration that causes excessive deceleration, for example, in the present embodiment, because of the relationship with step 20 described later for preventing excessive deceleration. Any value may be used as long as the desired deceleration characteristic is finally obtained. The downshift target acceleration may be a fixed value.

In step 10, a shift stage i (= g-1, g; current shift stage) after downshifting is obtained. Step
At 11, it is determined whether i is 0 or not. If YES (0), proceed to step 12, and if NO (1), step 13
Go to. In step 12, since the current gear is the first speed, the current instruction to the control unit 50 is maintained in order to select the first speed as it is because further downshift cannot be performed.

In step 13, the current gear stage is not the first speed, so downshifting is possible if required, so the turbine rotational speed Nt2 after downshifting is determined from the following equation. Nt2 = VSP × k Nt (i) k Nt (i); a constant determined by the shift stage after the downshift In step 14, the turbine torque (Tt2) after the downshift is obtained from the vehicle speed VSP and the turbine torque Tt map.

In step 15, the driving force (FCE2) after downshift is obtained from the following equation. FCE2 = Tt2 × k Tt (i) k Tt (i); a constant determined by the shift stage after the downshift. In step 16, the acceleration resistance (RESI-A after the downshift).
2) is calculated from the following formula.

RESI-A2 = (FCE2)-(RESI-I)-(RESI-RL) In Step 17, the acceleration resistance (RESI-A after the downshift is calculated.
2) is compared with the downshift target acceleration (TGT-RA). If RESI-A2 ≧ TGT-RA, step to calculate acceleration resistance (RESI-A2) when further downshifting.
In step 18, the current i is set to g, and the process returns to step 10.

On the other hand, if RESI-A2 <TGT-RA, a shift speed with an acceleration smaller than the downshift target acceleration (for example, excessive deceleration) is found, so the routine proceeds to step 19, Whether or not the driver actually intends to decelerate is checked as a material for determining whether or not the downshift is actually performed. In step 19, it is determined whether or not the throttle opening TVO is less than or equal to the deceleration intention determination opening (TVO-cnst).

If YES (TVO≤TVO-cnst), it can be determined that the driver intends to decelerate, so the routine proceeds to step 20 to actually perform the downshift. NO
If (TVO> TVO-cnst), it is assumed that the driver has no intention to decelerate, and in order to eliminate the discomfort to the driver by respecting the driver's will, a downshift for a downhill road is forced. The control is not performed, and this flow is ended as it is, and the shift control is performed according to the normal shift pattern (FIG. 5).

In step 20, since the driver actually intends to decelerate, a gear stage (= i + 1) obtained by adding 1 to the currently set gear stage i after downshift is selected,
The control unit 50 is instructed to change gears, and this flow ends.
As a result, the gear is downshifted to a gear that is one step larger than the gear that is too decelerating, so that excessive deceleration can be prevented and good deceleration characteristics can be obtained, thereby giving the driver a feeling of strangeness. Therefore, good downhill road control can be performed.

The above steps 3 to 20 constitute the vehicle shift request signal generating means according to the present invention. As described above, according to the present embodiment, when performing shift control on a downhill road, it is determined whether or not there is a downshift request (for example, an overtaking acceleration request) based on the driver's throttle operation, and the driver is willing to decide. When there is a downshift request based on the vehicle, the downhill shift control based on the running state of the vehicle (for example, according to the grade or maintaining the vehicle acceleration at a predetermined value) is prohibited while the driver's intention is based. When there is no downshift request, the downhill road shift control is performed based on the running state of the vehicle, so that the vehicle drivability on the downhill road can be improved without causing the driver to feel discomfort.

Further, in this embodiment, since the speed change step for obtaining the desired acceleration is calculated by the calculation, the speed change step for the separate downhill road control as in the prior art (Japanese Patent Publication No. 4-4351). Since it is necessary to have a selection map,
This is advantageous in terms of cost in terms of computer memory capacity and the like. In the present embodiment, the downhill road control is described as the one in which the desired acceleration is obtained by the downshift control, but it is of course applicable to the case where the downhill road control is performed so as to obtain the desired acceleration by the upshift control. .

Further, in the present embodiment, the shift request signal based on the driver's operation which is prioritized in the downhill road control has been described as represented by the throttle operation, but of course, the driver operates the shift lever (D range → second speed). Hold range, etc.)
It is also possible to make the shift request based on the driver's operation.

[0029]

As described above, according to the invention described in claim 1, when the shift control on the downhill road is performed,
Since the shift request based on the driver's operation is prioritized over the shift request based on the running state of the vehicle, when there is a shift request based on the driver's operation, the downhill road based on the running state of the vehicle is used. While the control is prohibited, if there is no shift request based on the driver's operation, downhill control based on the running state of the vehicle can be performed, so that the driver can drive the vehicle downhill without feeling discomfort. It is possible to improve the sex.

According to the second aspect of the invention, the shift request based on the running state of the vehicle when performing the shift control on the downhill road is the shift request for maintaining the vehicle acceleration at the predetermined value. If there is no shift request from the driver, it is possible to prevent the vehicle from decelerating too much or accelerating too much on the downhill road, so that better driver drivability on the downhill road can be obtained without causing the driver to feel uncomfortable. be able to.

According to the third aspect of the invention, when performing the shift control on the downhill road, a downshift request (for example, overtaking acceleration) is performed by the throttle operation that most directly, accurately and promptly responds to the driver's intention. Request),
When the request is made, the downhill shift control based on the running state of the vehicle (maintaining the vehicle acceleration at a predetermined value) is prohibited, while when there is no downshift request based on the driver's intention, the running state of the vehicle is changed. Since the downhill speed change control can be performed based on this, the control can be performed with high accuracy, and thus the vehicle drivability on the downhill road can be obtained without causing the driver to feel uncomfortable.

[Brief description of drawings]

FIG. 1 is a block diagram according to the present invention.

FIG. 2 is an overall configuration diagram of an embodiment of the present invention

FIG. 3 is a flowchart (part 1) explaining the shift control on a downhill road in the embodiment.

FIG. 4 is a flowchart (part 2) explaining the shift control on a downhill road in the embodiment.

FIG. 5 is a diagram showing a shift pattern in normal traveling.

FIG. 6 R / L (for calculating air resistance + rolling resistance) table

FIG. 7 Tt (turbine torque search) map

FIG. 8 TRA (for downshift target acceleration calculation) table

[Explanation of symbols]

 1 engine 2 automatic transmission 3 torque converter 4 speed change gear mechanism 6A solenoid valve 6B solenoid valve 7 throttle sensor 8 vehicle speed sensor 50 control unit

Claims (3)

[Claims] 1. A shift control device for an automatic transmission, which performs shift control based on a shift request signal, comprising: vehicle shift request signal generating means for generating a shift request signal based on a state of a vehicle when descending a slope; and a driver. Driver's gear shift request signal generating means for generating a gear shift request signal based on the operation, and prioritizing the gear shift request signal based on the driver's operation over the gear shift request signal based on the state of the vehicle at the time of downhill And a shift request signal selecting means for sending the shift request signal to the shift control device, the shift control device for an automatic transmission for a vehicle. 2. The shift control of the automatic transmission for a vehicle according to claim 1, wherein the shift request signal based on the state of the vehicle is a shift request signal for maintaining the vehicle acceleration at a predetermined value. apparatus. 3. The vehicular automatic transmission according to claim 1, wherein the shift request signal based on the driver's operation is a downshift request signal based on the driver's throttle operation. Shift control device.