JP2000213639A - Automatic transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To practice timing to transfer from downhill road control suitable for downhill road travelling to flat road control suitable for flat road travelling by a control device in a simple constitution in controlling a speed change schedule of an automatic transmission for a vehicle. SOLUTION: A release threshold value is previously specified and memorized in a release threshold value memory part 36 as a judgement standard to transfer to flat road control from downhill road control. The release threshold value is a rate of change of acceleration and is specified as a function of vehicle acceleration. Vehicle acceleration is detected by a sensor 26 or 28, a rate of change of acceleration is computed by an acceleration changing rate computing part 42, and a downhill road control release judging part 20 releases downhill road control and carries out instruction to transfer to flat road control when the rate of change of acceleration is higher than the release threshold value against vehicle acceleration at the time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission for a vehicle, and more particularly to the control of an automatic transmission which is controlled by different shift patterns when traveling on a flat road and traveling on a downhill road.

[0002]

2. Description of the Related Art In an automatic transmission for a vehicle, an appropriate gear ratio or the like is selected in accordance with a gear shift schedule stored in advance based on a running state of a vehicle and a driver's operation. The most commonly known method takes the vehicle speed as the running state of the vehicle and the throttle valve opening as the driver's operation, and selects the gear ratio according to these. Since the shift schedule is created based on traveling on a flat road, an appropriate gear ratio may not be selected when traveling on a slope. For example, when traveling on a downhill road, the throttle valve is often closed, so that it is determined that acceleration is unnecessary and a high gear ratio is selected. However, this does not allow the engine brake to operate. For this reason, it is necessary for the driver himself to perform a low gear ratio, for example, a range fixed to the second gear by operating a shift lever or the like.

[0003] In recent years, in order to solve the above-mentioned inconvenience, the transmission itself determines whether the vehicle is traveling on a flat road or a slope, and a shift schedule suitable for each traveling is determined. The selected transmission is in practical use. In these transmissions, when shifting from a downhill road that requires engine braking to a flat road that does not require engine braking, control suitable for downhill roads (hereinafter referred to as downhill road control) is released and the transmission is shifted to flat roads. The control shifts to suitable control (hereinafter, referred to as flat road control). Conventionally, determination of a flat road or a sloping road has been made based on a vehicle speed, a throttle valve opening, and an acceleration on a flat road. That is, when the vehicle is traveling on a flat road at a predetermined vehicle speed, the acceleration obtained at a predetermined throttle valve opening is used as a reference acceleration, and the acceleration obtained at the current throttle valve opening is compared with the reference acceleration. To determine the slope. Specifically, at a certain vehicle speed and throttle valve opening, if the reference acceleration has not been reached, it is determined that the vehicle is in an uphill state. to decide. The gradient can also be estimated depending on the degree of acceleration.

[0004]

The downhill road control is released,
In order to shift to normal flat road control, it is necessary to determine whether the current traveling road is a sloping road or a flat road.
In the conventional apparatus, as described above, the reference acceleration is obtained from the throttle valve opening and the vehicle speed, and the gradient is calculated from the relationship between the reference acceleration and the actual acceleration. Therefore, the relationship between the throttle valve opening and the reference acceleration corresponding to the vehicle speed has to be obtained and stored in advance. Therefore, there is a problem that the mounting capacity for storing is large, and the calculation load for calculating the reference acceleration and the gradient based on the reference acceleration is large.

[0005] In addition, when the release of the downhill road control is determined based on the gradient or the vehicle acceleration, the timing may deviate from the driver's sense.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and provides an automatic transmission that can reduce a mounting capacity and a calculation load for determining release timing of downhill road control. The purpose is to:

It is a further object of the present invention to provide an automatic transmission capable of making the timing of releasing the control of the downhill road suitable for the driver's feeling.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an automatic transmission for a vehicle according to the present invention includes: a flat road control in which a shift speed is selected according to a shift pattern suitable for flat road traveling; A downhill road control for selecting a gear position at which engine braking can be obtained as compared with the flat road control, when a slope traveling is detected, and a coasting traveling detecting means for detecting a coasting traveling state A vehicle acceleration calculating means for calculating a vehicle acceleration; and a vehicle acceleration change rate calculating means for calculating a change rate of the vehicle acceleration, wherein the selecting means determines that a relationship between the vehicle acceleration and the change rate of the acceleration is predetermined. Is switched from downhill road control to flat road control when the above condition is satisfied.

According to this configuration, the timing of the transition from the downhill control to the flat road control is determined based on the relationship between the vehicle acceleration and the rate of change of the acceleration. Therefore, it is necessary to calculate the gradient and to calculate the gradient. There is no need to memorize important information. Further, it is possible to determine the timing of the transition closer to the driver's sensitivity.

Further, in each of the above-mentioned automatic transmissions for vehicles, the condition for switching from the downhill road control to the flat road control can be changed according to the traveling environment. For example, the switching condition can be changed between a straight downhill road and a bent downhill road.

[0011]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. FIG. 1 shows a configuration of a part related to control of the automatic transmission according to the present embodiment. The control unit 10 calculates an appropriate shift speed based on the outputs of various sensors for detecting the running state of the vehicle and the shift schedule map stored in the shift schedule map storage unit 12 in advance. A hydraulic circuit control unit 16 for controlling a solenoid valve of the hydraulic circuit according to the above. By controlling the hydraulic circuit, a hydraulic pressure is supplied to a predetermined hydraulic clutch inside the transmission, and the calculated shift speed is selected. The control unit 10 further includes a control selection unit 18 that determines whether the traveling road is a flat road, an uphill road, or a downhill road, and selects which control is appropriate. The shift calculation unit 14 performs the control selected by the control selection unit 18, that is, flat road control (normal control) suitable for flat road traveling, uphill road control suitable for uphill traveling, and downhill traveling suitable for downhill traveling. A shift schedule map corresponding to any of the controls is read, and a shift speed is selected according to the map. The control selection unit 18
There is provided a downhill road control release determination unit 20 that releases the downhill road control under a predetermined condition and determines to return to the normal flat road control. The downhill road control release determination unit 20 includes an acceleration change rate calculation unit 42. The acceleration change rate calculation unit 42 calculates the change rate of the vehicle acceleration based on the value detected by the vehicle speed sensor 26 or the vehicle acceleration sensor 28. The rate of change of the acceleration is calculated as an average value for a predetermined period of time, for example, 2 seconds, because the instantaneous value has large variations. In addition,
The control unit 10 includes a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory), and the like.
8 and functions as each determination unit, calculation unit, and change unit included therein.

The downhill road control release determination section 20 mainly includes a throttle valve opening sensor 22, a brake sensor 24, a vehicle speed sensor 26, a vehicle acceleration sensor 28, a gear position among various sensors related to control of the automatic transmission. The determination is performed based on the detection values of the sensor 30, the shift range sensor 32, and the turning sensor 34 and the rate of change of the acceleration.
This determination is made by comparing the calculated vehicle acceleration and the rate of change of the acceleration with the release threshold. The release threshold is, as shown by the thick solid line in FIG.
Expressed as a function of vehicle acceleration in acceleration change rate coordinates. The locus of the rate of change of the acceleration with respect to the vehicle acceleration is
On the coordinate plane, from the upper right direction of the release threshold line segment to the lower left direction (the direction in which the negative value increases) from the upper right direction of the release threshold line segment across the release threshold line segment Change. More specifically, for example, the coordinates indicated by the calculated vehicle acceleration and the acceleration change rate are indicated by a point Pa (G
If it is below the line indicating the release threshold in the figure as in (a, dGa), it is determined that it is not time to release the downhill road control. On the other hand, the coordinates indicated by the calculated vehicle acceleration and the acceleration change rate are represented by a point Pb (Gb, dGb),
If it is above the release threshold in the figure, it is determined that the downhill road control is released. The release threshold is stored in the release threshold storage unit 36 of FIG.
Reads the release threshold value from here and makes the above determination.
If it is determined that the shift should be released, the shift calculation unit 14
Is instructed to shift from downhill road control to flat road control. The shift calculating unit 14 changes the shift schedule map based on the above-mentioned instruction, and performs an operation regarding the shift timing according to the map of the flat road control.

The above-mentioned release threshold value can be changed in accordance with the traveling environment by storing a different value for each different traveling environment in the above-mentioned release threshold storage section 36. The traveling environment is determined by the traveling environment determination unit 38. The driving environment is
For example, whether the vehicle is traveling on a straight road or a curved road. The traveling environment determination unit 38 determines a straight road or a curved road based on the output of the turning sensor 34. If a turn is not detected within a predetermined time in the past, it is determined that the vehicle is traveling on a straight road, and if a turn is detected, it is determined that the vehicle is traveling on a curved road. In accordance with this determination, the threshold changing unit 40 instructs the downhill road control canceling unit to change to a canceling threshold suitable for the determined traveling environment. Specifically, the turning sensor can be a sensor that detects the steering operation angle or a yaw rate sensor.

Further, as the driving environment, the presence or absence of a surrounding vehicle can be considered. Using a photographing device such as a CCD camera or a radar ranging device, the presence or absence of a preceding vehicle, a following vehicle, the distance between vehicles, etc. are detected, and the release threshold corresponding to this is used to determine release of downhill road control. it can.
The above-described combination of the straight road-curved road, the presence / absence of a preceding vehicle, the presence / absence of a succeeding vehicle, etc., can be used to set a release threshold value, or a reference release threshold value can be set for traveling. This may be corrected in accordance with the environment and set as a release threshold.

[0015] The traveling environment can also be determined using the information of the vehicle navigation system. In the vehicle navigation system, since the current position of the vehicle and the road on which the vehicle is traveling can be specified, it is possible to determine whether the road is a straight road or a curved road. In a navigation system such as VICS that can acquire traffic congestion information and the like, the release threshold can be changed depending on the degree of traffic congestion at present or ahead.

Further, the release threshold value is prepared according to the shift range and the shift speed in which the downhill road control is executed. For example, in the case of a 5-speed automatic transmission, if the third to fifth speeds are to be subjected to downhill road control, the gears are for 3 → 4th gear, 4 → 5th gear, and 3 →
Each release threshold for the fifth speed is prepared. Alternatively, a standard release threshold value may be determined, and the standard release threshold value may be corrected according to the selected shift range and shift speed, and may be used as the release threshold value. The release threshold is not related to the vehicle speed because of the relationship of the rate of change of the acceleration with respect to the vehicle acceleration. However, in order to determine the release timing more accurately, For example, 10-15 km /
It is desirable to set and change the release threshold for each h. That is, a plurality of release thresholds represented by the rate of change of the acceleration with respect to the vehicle acceleration are set for one traveling environment in accordance with the vehicle speed.

FIGS. 3 and 4 show examples of the release threshold. FIG. 3 shows a release threshold suitable for traveling on a straight downhill, and FIG. 4 shows a release threshold suitable for traveling on a curved downhill. The points plotted with “+” in the figure indicate that the driver evaluated the timing as “slow” among the timings in which the coasting was performed on the downhill road at the third speed and the fellow passenger shifted up to the fourth speed by the shift operation. That is the point. The points plotted with “□” indicate the optimal shift-up timing indicated by the driver operating the switch. 3 and 4, the release threshold is indicated by a thick solid line.

FIGS. 5 and 6 are data obtained by rewriting the data of FIGS. 3 and 4 into a coordinate plane of vehicle speed (vehicle speed) -road gradient. The evaluation of the release timing on this coordinate plane is the same as that performed conventionally. The road gradient is obtained from the acceleration of the vehicle at a certain throttle valve opening, as in the prior art. Optimal release timing points for release thresholds shown in FIGS. 3 and 4 (points indicated by “□” in the figures)
It can be seen that the variation is smaller than in FIGS. 5 and 6. Therefore, when judging the timing to cancel the downhill road control, it is considered more preferable to make the judgment focusing on the relationship between the acceleration and the rate of change of the acceleration. This is presumed to be because human sensitivity is more sensitive to acceleration and changes in acceleration than the absolute value of speed. When determining the release timing of the descending slope control from the vehicle acceleration and the rate of change of the acceleration as in the present embodiment, there is no increase in the calculation load for calculating the gradient, the capacity for storing the reference acceleration, etc., and the apparatus is simplified. Can be

FIG. 7 is a flowchart showing a control for canceling downhill road control and shifting to flat road control in the automatic transmission according to the present embodiment. First, it is determined whether the downhill road control is currently being executed (S11).
0). If not, the flow ends.
If the vehicle is on a downhill road, various sensor signals are read (S102), and the traveling environment is determined (S104). Further, it is determined that the accelerator pedal is released and the brake is not operated (S106). In the present embodiment, this determination is based on the fact that the throttle valve opening sensor 22 detects the opening 0 and the brake sensor 2
4 is performed when a non-operation state is detected. This condition is, in other words, a condition for determining the coasting. Therefore, in this embodiment, the throttle valve opening sensor 22
And the brake sensor 24 function as coasting traveling determination means. If this condition is not satisfied, this flow ends and the downhill road control is not released. If the condition of step S106 is satisfied, a release threshold corresponding to the traveling environment obtained in step S104 is selected (S108). Furthermore, from the selected ones, the shift range, the shift speed,
A release threshold according to the acceleration is selected (S110).

Then, it is determined whether the calculated rate of change in acceleration is equal to or greater than the release threshold value for the calculated vehicle acceleration (S112). If the rate of change of acceleration does not exceed the release threshold, it is determined that the downhill road control should not be released, and this flow ends. If the acceleration change rate is equal to or greater than the release threshold, it is determined that it is time to release the downhill road control (S114).

FIG. 8 shows an example in which the downhill road control release determination section 20 is configured as a neural network (hereinafter referred to as NN). The vehicle acceleration and the rate of change of acceleration at the current time, the vehicle acceleration and the rate of change of acceleration one second before and two seconds before, and the determination value determined by the driving environment determination unit are input to the illustrated neural network. Estimate release of slope control. The estimated value is learned and configured to output a continuous value of 0 to 1, with 0 when the release timing is early, 1 when it is late, and 0.5 when it is optimal.
The case where the estimated value is 0.5 corresponds to the above-described cancellation threshold. FIG. 9 shows the correspondence between the release timing and the teaching value to the NN.

Further, the NN can be configured as shown in FIG. That is, a configuration may be adopted in which the cancellation is estimated from the current time, the acceleration and the acceleration change rate before the predetermined time, and the estimated value is corrected by the driving environment determination value without inputting the driving environment determination value to the NN.

FIGS. 11 to 13 show a comparison between the estimation result of the release timing of the downhill road control by the NN and the timing optimized by the driver using the traveling data on the straight downhill road shown in FIG. 3 and the like. I have. 11 shows a vehicle speed of 50 km / h, FIG. 12 shows a vehicle speed of 60 km / h, and FIG.
3 shows the case where the vehicle speed is 70 km / h. In these figures, the release timing (estimated value 0.5) estimated by the NN is indicated by “□”, and the optimal release timing based on the driver's declaration is indicated by “○”.

As shown in the figure, when the vehicle speed is 50 km / h, the timing estimated by the NN and the timing declared by the driver agree well. Vehicle speed 60km / h
In the case of, the timing was slightly earlier than the timing declared by the driver. On the other hand, when the vehicle speed was 70 km / h, the speed was slightly lower.

If the estimated value is 0.5 or more, the downhill road control is released. Therefore, whether the vehicle is estimated to be slow or optimal, the result is "release of downhill road control". Will be the same. Therefore, it is also possible to adopt a configuration in which the early release is estimated to be 0 and the late release is both estimated to be 1 when the release is late.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control unit of an automatic transmission according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a release threshold.

FIG. 3 is a diagram illustrating an example of a release threshold of the embodiment illustrated in FIG. 1;

FIG. 4 is a diagram illustrating an example of a release threshold of the embodiment illustrated in FIG. 1;

FIG. 5 is a diagram showing an example of a release threshold determined by a road gradient.

FIG. 6 is a diagram illustrating an example of a release threshold value determined based on a road gradient.

FIG. 7 is a diagram showing a control flow relating to cancellation of downhill road control of the present embodiment.

FIG. 8 is a diagram showing an example in which a downhill road control canceling unit is configured by a neural network.

FIG. 9 is a diagram illustrating an example of a teaching value of a neural network.

FIG. 10 is a diagram showing another example in which the downhill road control canceling unit is configured by a neural network.

FIG. 11 is a diagram showing an example in which a release timing of downhill road control estimated by a neural network is compared with a driver's declaration timing.

FIG. 12 is a diagram illustrating an example in which a release timing of downhill road control estimated by a neural network is compared with a driver's declaration timing.

FIG. 13 is a diagram showing an example in which a release timing of downhill road control estimated by a neural network is compared with a driver's declaration timing.

[Explanation of symbols]

20 Downhill road control release determination unit, 22 Throttle valve opening sensor (coasting traveling detecting means), 24 Brake sensor (coasting traveling detecting means), 26 Vehicle speed sensor, 28
Vehicle acceleration sensor, 36 release threshold storage unit, 38
A driving environment determining unit, a threshold changing unit, an acceleration change rate calculating unit;

Continuing from the front page (72) Inventor Kisaburo Hayakawa 41, Chuchu-Yokomichi, Oku-cho, Nagakute-cho, Aichi-gun Aichi No. 1 Inside Toyota Central Research Laboratory Co., Ltd. No. 1 Inside Toyota Central Research Institute Co., Ltd. (72) Inventor Masuji Oshima 41-cho, Yokomichi, Oku-cho, Nagakute-cho, Aichi-gun Aichi Prefecture No. 1 Inside Toyota Central Research Institute Co., Ltd. (72) Inventor Yasuya Nakamura 1 Toyota Town, Toyota City (72) Inventor Kazuyuki Shiiba 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Fumito Nomori 1 Toyota Town, Toyota City, Aichi Prefecture Toyota (72) Inventor Yoshio Ito 1 Toyota Town, Toyota-shi, Aichi F-term (reference) 3J052 AA04 BA05 BA14 FB31 GC13 GC23 GC46 GC51 GC64 GC66 GC72 HA01 KA01 LA01

Claims (2)

[Claims] An automatic transmission for a vehicle that selects an appropriate shift speed based on a running state of a vehicle and an operation of a driver, wherein the shift speed is selected by a shift pattern suitable for flat road traveling. A downhill road control for selecting a gear position at which engine braking can be obtained as compared with the flat road control when downhill traveling is detected; and a coasting detecting a coasting traveling state. Traveling detection means, a vehicle acceleration calculation means for calculating a vehicle acceleration, and a vehicle acceleration change rate calculation means for calculating a change rate of the vehicle acceleration, wherein the selection means determines a difference between the vehicle acceleration and the change rate of the acceleration. An automatic transmission for a vehicle that switches from downhill road control to flat road control when the relationship satisfies a predetermined condition. 2. The automatic transmission for a vehicle according to claim 1, wherein a condition for switching from the downhill road control to the flat road control is changed according to a traveling environment.