JP2001090831A - Shift-down direction device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance safety and reliability of a device adapted to control behavior for vehicle according to outside monitoring. SOLUTION: A microcomputer 1 recognizes a running state in front of own vehicle and computes a distance to the foregoing vehicle on the basis of preview information obtained by a preview sensor 5 and a navigation unit 6. Also the microcomputer 1 directs TCU 7 to downshift when it determines the state to downshift basing on the recognition result, and it directs TCU 7 to cancel shift- down when it judges the state not to need to downshift. The microcomputer 1 does not direct TCU 7 to cancel shift-down when it determines that a safe distance to the foregoing vehicle cannot be secured by canceling shift-down based on the computed distance to the foregoing vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift-down instructing device for instructing a shift-down of an automatic transmission in accordance with a running condition in front of a vehicle. It relates to a shift-down release determination performed later.

[0002]

2. Description of the Related Art There has been proposed a technique for grasping a running condition ahead of a vehicle based on navigation information and preview information obtained from a preview sensor, and decelerating by downshifting as necessary. For example, JP-A-8-20
Japanese Patent Application Laid-Open No. 2989 and Japanese Patent Application Laid-Open No. HEI 8-194886 disclose that if the road ahead of the vehicle is curved, the vehicle speed when entering the curved road is too high, that is, if it is determined that the vehicle is overspeeding, A technique for executing a downshift before entering a curve is disclosed. In this way, by decelerating in advance just before entering a curve, it is possible to realize a good curve traveling property without giving a driver an uncomfortable feeling.

[0003]

By the way, when the vehicle decelerates by downshifting and passes through a curve, the downshift mode is released, and the shift speed in the normal shift mode is set. In many cases, the shift up is automatically performed by returning to the normal mode, and therefore, the own vehicle starts to accelerate. At this time, if there is a preceding vehicle ahead of the own vehicle, there is a possibility that the inter-vehicle distance from the preceding vehicle may be sharply reduced by acceleration due to upshifting, and thus there is a safety problem.

[0004] The present invention has been made in view of such problems, and an object of the present invention is to further improve the safety and reliability of a device that controls the behavior of a vehicle according to monitoring outside the vehicle.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a shift-down instructing device for an automatic transmission, which recognizes a running situation ahead of a vehicle based on preview information, and Based on the recognition result of the inter-vehicle distance to the preceding vehicle ahead and the recognition result of the recognition means, when it is determined that the situation has to be decelerated, the shift down is instructed and the situation is no longer decelerated. And instructing means for instructing cancellation of downshifting when it is determined. The instructing unit is configured not to instruct the cancellation of the downshift when it is determined that the safe inter-vehicle distance cannot be secured by releasing the downshift based on the inter-vehicle distance to the preceding vehicle calculated by the recognizing unit. Have been.

If the instructing means determines that a safe inter-vehicle distance cannot be secured by releasing the downshift, the instructing means issues an instruction to cancel the downshift until it determines that a safe inter-vehicle distance can be secured. It is preferable to suspend.

[0007] It is preferable that the instructing means determines whether or not the vehicle should be decelerated based on a curve present ahead of the vehicle and the vehicle speed of the vehicle.

[0008] It is desirable that the instructing means determines whether or not the vehicle should be decelerated on the basis of the positional relationship between the own vehicle and the preceding vehicle existing in front of the own vehicle.

On the other hand, the instructing means determines whether or not the downshift can be released based on the predicted acceleration of the own vehicle which occurs when the downshift is released and the inter-vehicle distance to the preceding vehicle calculated by the recognizing means. You may. At that time, a running resistance calculating means for calculating the running resistance of the vehicle is further provided,
It is preferable to determine whether or not to cancel downshifting in consideration of the running resistance calculated by the running resistance calculating means. Further, a road gradient calculating means for calculating a road gradient at the own vehicle position is further provided, and it is determined whether or not the own vehicle accelerates after downshifting in consideration of the road gradient calculated by the road gradient calculating means. desirable.

[0010]

FIG. 1 is a block diagram showing the overall configuration of a transmission system using a downshift instruction device according to the present embodiment. The microcomputer 1 serving as the downshift instruction device includes vehicle state signals (vehicle speed υ, engine speed NE, throttle opening θ, etc.) obtained from the sensors 2 to 5, navigation information obtained from the navigation unit 6, and A shift signal P indicating the current set shift speed, which is information output from the transmission control unit (TCU) 7, is input. The microcomputer 1 recognizes the running condition ahead of the vehicle based on the input information, and instructs the TCU 7 to decelerate according to the recognition result.
WN and TRGT are output. When a downshift is instructed by these instruction signals DOWN and TRGT, the TCU 7 temporarily suspends the shift control in the normal mode, and performs the shift control according to the instruction (shift down mode).

FIG. 6 is a flowchart showing a shift control procedure performed in the TCU 7. First, in step 51, the TCU 7 outputs the downshift instruction signal DOW.
N is read, and it is determined whether or not the instruction signal DOWN is at the "1" level, that is, whether or not execution of downshift is instructed. In a normal traveling state, the downshift instruction signal DOWN is set to the “0” level. Therefore, as long as the downshift instruction signal DOWN is "0", the shift control in the normal mode in step 52, that is, the vehicle speed υ as shown in FIG.
And the shift stage GR is set based on the shift map based on the throttle opening θ. The TCU 7 changes the speed of the automatic transmission 9 (hereinafter, referred to as AT) to the speed GR.
Is output to the hydraulic control circuit 8 (step 54). The hydraulic control circuit 8 controls an automatic transmission (AT) 9 in accordance with an instruction from the engagement control signal.
Each solenoid constituting the middle hydraulic control mechanism 9a is operated. Thereby, each friction engagement element (clutch or brake) constituting the friction engagement mechanism 9b in the AT 9 is engaged / disengaged, and the AT 9 shifts to the shift speed (for example, four forward speeds, one reverse speed) specified by the TCU 7. Is set.

On the other hand, shift down instruction signal DO
If WN is at the “1” level, that is, if downshift execution is instructed (step 51), a shift setting in the downshift mode is performed (step 5).
3). In this mode, the shift speed GR is forcibly set (that is, without reference to the shift map shown in FIG. 9) to the target shift speed TRGT (specified by the instruction signal TRGT from the microcomputer 1). And TC
U7 outputs to the hydraulic control circuit 8 an engagement control signal for setting the gear position of AT9 to the gear position GR, that is, the target gear position TRGT (step 54).

The vehicle speed sensor 2, the engine speed sensor 3, and the throttle opening sensor 4 are well-known sensors used to calculate the vehicle speed υ, the engine speed NE, and the throttle opening θ, respectively. Further, the preview sensor 5 is a sensor that outputs a running situation ahead of the vehicle as preview sensor information. In this embodiment, a well-known stereo image processing device including a pair of CCD cameras and an image processing system is used as the preview sensor 5.
Based on a pair of captured images obtained from each CCD camera, it is possible to obtain three-dimensional position information including the distance to an object (preceding vehicle or road shape) existing ahead.
In addition, a monocular camera, a sensor using a millimeter wave or a laser wave, or a sensor using them in combination may be used as the preview sensor 5 other than the stereo image processing device.

The navigation unit 6 is a CD-RO
By using road map information stored in a storage medium such as M or DVD and GPS technology, navigation information including the position, traveling direction, road shape, and the like of the vehicle is output. The microcomputer 1 matches the preview sensor information from the preview sensor 5 with the navigation information from the navigation unit 6 and uses the matched information as “preview information” (that is, to recognize the running situation ahead of the vehicle). As a result, the reliability of recognition of the running situation ahead of the vehicle is ensured.

FIG. 2 is a flowchart showing a main routine of a deceleration instruction according to this embodiment. The microcomputer 1 repeatedly executes a series of procedures shown in the flowchart at predetermined intervals. First, in step 1, preview information and various sensor information υ, N
E, θ, etc. are read.

Next, the running condition ahead of the vehicle is recognized based on the preview information and the navigation information (step 2). Specifically, the three-dimensional road shape, the presence or absence of a preceding vehicle, the distance between the own vehicle and the preceding vehicle (inter-vehicle distance), and the like are recognized. An important matter to be recognized in relation to the present embodiment is detection of a curve existing ahead. As a pattern forming one curve, there are a case where the curve is formed by a single node as shown in FIG. 11 and a case where the curve is formed by a plurality of nodes as shown in FIG. The information on these nodes can be obtained from the navigation information, and includes the coordinate information of discrete points on the road with respect to the own vehicle. The road shape is represented as a polygonal line by a line connecting the adjacent nodes.

The node Pj-1 (coordinate (x [j-
1], y [j-1])) and Pj (coordinates (x [j], y [j])) basically satisfy the following two conditions, each node P
It is determined that j-1 and Pj belong to the same curve.

(Same Curve Conditions) 1. Distance L [j] between adjacent nodes Pj-1 and Pj is smaller than a predetermined value. Node angles t [j-1] of adjacent nodes Pj-1 and Pj,
The sign of t [j] is the same

Here, the distance L [j] between the nodes Pj is calculated by the following equation.

L [j] = ｛(x [j] −x [j−1]) ² + (y [j] −y
[j-1]) ² ｝ ^1/2

The node angle t [j] of the node Pj is calculated by the following equation.

## EQU2 ## t [j] = sin ^-1 [｛(x [j-1] −x [j]) (y [j] −
y [j + 1])-(x [j] -x [j + 1]) (y [j-1] -y [j])｝
/ (L [j] L [j + 1])]

From the same curve conditions, it is determined that the nodes P1, Pj-1, Pj, and Pj + 1 shown in FIG. 11 form separate curves. Further, it is determined that the node groups Pj-1 to Pj + 2 shown in FIG. 12 form one curve.

In step 3 following step 2, a determination speed Vth according to the shape of the curve ahead is calculated. The determination speed Vth indicates the upper limit value of the vehicle speed allowed at the current position of the vehicle in relation to the curve ahead, and the deceleration determination in step 5 (shift down or not).
Is used as a determination threshold value when performing. FIG.
9 is a flowchart showing a detailed calculation procedure of a determination speed Vth in step 3.

First, a road surface friction coefficient μ (hereinafter, road surface μ)
And the road gradient SL is estimated (step 1).
2). The road surface μ can be estimated based on the yaw rate, the steering angle, the lateral acceleration, and the vehicle speed, for example, as disclosed in Japanese Patent Application Laid-Open No. H8-2274. The method of calculating the road gradient SL will be described later.

In a step 13 following the step 12, a maximum value of the deceleration that does not cause a slip on a certain road surface μ, that is, an allowable deceleration β is calculated. The allowable deceleration β can be obtained by correcting the value specified using the road surface μ calculated in step 12 as a basic parameter using the road gradient SL calculated in step 12 as well. Note that the allowable deceleration β
For the specific calculation method of
Please refer to it if necessary because it is disclosed in Japanese Patent Publication No.

Then, regarding the forward curve specified in step 2 described above, the target node P
Permissible approach speed Vap of trgt and target node Ptrgt
Is calculated (step 14). Here, the “target node Ptrgt” is a node having the smallest curve radius of curvature in one curve. The allowable vehicle speed when entering a certain curve existing ahead of the own vehicle may be set based on a node that should decelerate and pass the most because the radius of curvature is minimum. Therefore, in the road shape shown in FIG. 11, each node P1, Pj-1,
Pj and Pj + 1 become the target nodes Ptrgt, respectively.
In the road shape shown in FIG. 12, among the node groups Pj-1 to Pj + 2 forming one curve, the node Pj-1 having the smallest radius of curvature is the target node Ptrgt in the curve. The curve radius of curvature r [j] at a certain node Pj can be calculated based on three points including the nodes Pj-1 and Pj + 1 before and after it.

Based on the radius of curvature of the specified target node Ptrgt, the approach speed Vap allowed to pass through the target node Ptrgt is calculated by the following method. First, prior to calculating the allowable approach speed Vap, the allowable lateral acceleration gv is calculated. At the time of passing through a curve, the limit value of the lateral acceleration becomes smaller as the road surface μ becomes smaller. Even at the same vehicle speed, the lateral acceleration increases as the radius of curvature of the curve decreases. Based on such knowledge, the lateral acceleration can be calculated using the road surface μ and the radius of curvature of the curve of the target node Ptrgt as basic input variables. Then, the calculated lateral acceleration is used as the road gradient S.
By correcting with L, the allowable lateral acceleration gv is calculated. It should be noted that a detailed calculation method of the allowable lateral acceleration gv is disclosed in Japanese Patent Application Laid-Open No. H11-83501.

The allowable approach speed Vap is calculated from the allowable lateral acceleration gv and the curve radius of curvature rtrgt of the target node Ptrgt.
It can be calculated by the following equation. As can be seen from the equation, the smaller the allowable lateral acceleration or the smaller the radius of curvature of the curve, the lower the speed allowed when entering the curve.

Vap = (gv × rtrgt) ^1/2

This value may be corrected according to the depth of the curve or the road width, and the corrected value may be used as the allowable approach speed Vap. In this case, the allowable approach speed Vap is set to decrease as the curve depth increases or the road width decreases.

In step 15 following step 14, the allowable approach speed Vap at the target node Ptrgt
Thus, the determination speed Vth indicating the upper limit of the vehicle speed at the current position of the own vehicle is calculated. The determination speed Vth reaches the target node Ptrgt when the distance from the current position to the target node Ptrgt (the distance is L) is reduced by K% (for example, 50%) of the allowable deceleration β. The speed is such that the vehicle speed sometimes reaches the allowable approach speed Vap. As an example, the determination speed Vth can be obtained by the following equation.

Vth = (Vap ² ) + 2 × (K × β) L) ^1/2

As described above, the allowable approach speed Vap for the curve ahead and the distance L to the target node Ptrgt
And the allowable deceleration β can be specified, the upper limit value (determination speed Vth) of the vehicle speed that the vehicle can take at the current position can be calculated backward. Then, by comparing the vehicle speed に お け る at the current position with the determination speed Vth in step 5 later, it is determined whether or not the vehicle speed 過 is excessive relative to the entry of the curve, that is, the necessity of deceleration is determined.

In step 4 following step 3, it is determined whether the deceleration execution flag FDS is "1". The deceleration execution flag FDS is initially set to "0". Therefore, the process proceeds from step 4 to step 5 when the flag FDS is "0".

In step 5 following step 4, it is determined whether or not it is a situation to decelerate. In particular,
The determination speed Vth calculated in step 3 is compared with the current vehicle speed υ calculated by the vehicle speed sensor 2. If the vehicle speed で is equal to or lower than the determination speed Vth, it is determined that the vehicle can enter a forward curve at the current vehicle speed と も without deceleration. Therefore, in this case, the process proceeds to steps 9 and 11 from the negative determination in step 5, and a “0” level shift-down instruction signal DOWN is output to the TCU 7. The shift-down instruction signal DOWN is normally set to the “0” level (instructing normal mode shift control) unless there is a special traveling condition in which it is necessary to automatically decelerate. Upon receiving the downshift instruction signal DOWN at the “0” level, the TCU 7 performs shift control in the normal mode (step 52).

On the other hand, if an affirmative determination is made in step 5, that is, if the vehicle speed 大 き い is greater than the determination speed Vth, it is determined that the current vehicle speed υ is excessively large in order to safely enter a curve ahead. I do. In this case, the microcomputer 1 determines that it is necessary to decelerate, and proceeds to steps 6 and 11, where the microcomputer 1 instructs the TCU 7 to shift down to perform deceleration before entering the curve. Specifically, shift down instruction signal DOWN attains "1" level, and deceleration execution flag FDS is set at "1" level. Further, the target shift speed TRGT after the downshift is set. As the target shift speed TRGT, a shift speed is set as one paragraph from the current shift speed in all ranges including the D range (for example, if the current shift speed is 4th speed, 3rd speed) is set. Further, in the case of the D range and the current shift speed is the fourth speed (or the third speed), the third speed (or the second speed) may be set as the target shift speed TRGT. Further, depending on the degree of required deceleration, one or two gears from the current gear
The gear stage set as a paragraph may be set as the target gear stage TRGT. Further, a method of changing the shift mode itself is also possible. For example, if the current shift mode is the D range, it may be reduced to three ranges.

As a result, the TCU 7 temporarily suspends the normal mode, and executes the shift control in the downshift mode, that is, the downshift to the target shift speed TRGT.

Next, a procedure for releasing the deceleration instruction will be described. When execution of downshift is instructed in a certain cycle, the deceleration execution flag FDS is set to "1" in step 6 in that cycle. Therefore,
In the next cycle, the procedure from step 7 to step 7 onward is executed. First, in step 7, it is determined whether or not the situation to decelerate is gone. This determination is made based on the passage of the curve including the target node Ptrgt, the running state of the own vehicle, and the like. If a negative determination is made in step 7 (for example,
If the car has not yet passed the curve), go to step 10,
11, the "1" level shift down instruction signal DO
WN is output to TCU7. Therefore, the shift-down mode is not released, so that the shift speed of AT9 is maintained at the target shift speed TRGT (that is, the downshift state is maintained). The shift-down instruction signal DOWN is maintained at the "1" level until the deceleration is no longer necessary, and therefore the mode does not return to the normal mode.

On the other hand, when it is no longer the situation to decelerate,
In that cycle, the process proceeds from step 7 to step 8, where it is determined whether the downshift can be released. If it is determined from the determination result in step 8 that the downshift can be released, the downshift instruction signal DOW is issued.
N switches from the “1” level to the “0” level, and the deceleration execution flag FDS is also reset to “0”.
As a result, the mode is returned from the downshift control to the normal mode, and the normal shift control is restarted (step 5 in FIG. 6).
2). On the other hand, if it is determined that the downshift should not be released, the downshift instruction signal DOWN remains at the “1” level and the deceleration execution flag FD
S is also maintained at “1”. Thus, in the current cycle, the downshift mode is continued without restarting the normal mode (step 53 in FIG. 6).

FIG. 3 is a flowchart showing a detailed procedure of the shift-down release determination. First, step 21
In, it is determined from the recognition result based on the preview information whether or not a preceding vehicle exists on a traveling path ahead of the own vehicle (within a predetermined monitoring distance range). If there is no preceding vehicle, there is no need to consider the inter-vehicle distance after the downshift is released. Therefore, in this case, the process proceeds to step 25, where the downshift instruction signal DOWN is switched from the "1" level to the "0" level, and the shift execution flag FDS is reset to "0". As a result, the TCU 7 ends the downshift mode and resumes the interrupted shift control in the normal mode.
In other words, when there is no preceding vehicle, the shift control in the normal mode is immediately resumed when the running condition in which the vehicle should be decelerated disappears. Usually, this often causes an upshift.

On the other hand, if an affirmative determination is made in step 21, that is, if there is a preceding vehicle, it is not necessary to immediately return to the normal mode. Only when it is determined that For that purpose, first, the inter-vehicle distance DS to the preceding vehicle is specified (step 22). The inter-vehicle distance DS can be calculated from the preview information using a known method. Then, in consideration of the inter-vehicle distance DS, it is determined whether it is safe to release the downshift (step 23). FIG. 4 is a flowchart showing a detailed procedure of the safety determination.

First, in step 31, referring to the shift map shown in FIG. 9, the shift stage set when the downshift is released (the TCU 7 may receive a scheduled shift stage signal in the normal mode). , Target gear TR
Specified as GT. Next, from the shift map reference result, it is determined whether or not an upshift occurs after the upshift is released (step 32). If the upshift does not occur even if the downshift is canceled, the inter-vehicle distance with the preceding vehicle does not suddenly decrease, and there is no problem even if the normal mode is immediately resumed. Therefore, in this case, the process proceeds from the negative determination in step 32 to step 25 in FIG.
N is switched to the “0” level, and the shift execution flag FDS is reset to “0”. Thereby, TCU
7 ends the downshift mode and restarts the shift control in the normal mode.

On the other hand, if an affirmative determination is made in step 32, that is, if a shift-up occurs after the shift-down is released, the process proceeds to step 33. This step 32
, Based on the current engine speed NE calculated from the sensor 3 and the current throttle opening θ calculated from the sensor 4, refer to the engine torque calculation map shown in FIG. Tq is calculated. Then, in step 34, the predicted driving force F after the upshift is calculated from the current output torque Tq and the gear ratio Rtrgt of the target gear stage TRGT based on the following equation. In the equation, Rfinal is a final gear ratio (constant), and C is a tire radius (constant).

F = Tq × Rtrgt × Rfinal / C

In step 35 following step 34, the running resistance r, that is, the resistance received when the vehicle travels in the air, is calculated from the current vehicle speed 算出 calculated from the sensor 2 by the following equation. Here, the constant A is the entire projected area, the constant Cd is the air resistance coefficient, and the constant ρ is the air density.

R = A × Cd × 1 / 2ρ × υ ²

Then, in step 36, the road gradient SL is calculated based on the current vehicle speed υ and the current generated driving force F (note that this is the driving force at the gear before the upshift). FIG. 5 is a flowchart showing a detailed procedure for estimating the road gradient. First, step 4
1, the generated driving force F at the current gear P is
The current output torque Tq calculated in step 22
And the gear ratio R of the current gear stage P, and is obtained by the same calculation formula as the above-described Expression 5.

Next, in step 42, the road gradient SL is calculated from the current vehicle speed υ and the current generated driving force F calculated in step 34 with reference to the road gradient estimation map shown in FIG. . The road gradient estimation map is
This graph shows a change in the generated driving force F with respect to the vehicle speed に for each road gradient. Therefore, if the current vehicle speed υ and the generated driving force F are specified, the road gradient SL at that time is determined.
Can be estimated.

At step 37 following step 36, the target driving force F [N] (the driving force at the target gear stage TRGT after the downshift is released), the running resistance r [N], and the road gradient SL [degree] are calculated based on the target driving force F [N]. The acceleration α (predicted acceleration after downshift release) of the shift speed TRGT is calculated by the following equation. Note that the constant g in the equation is a gravitational acceleration.

Α = F / W− (r / W−g × sinSL)

Then, in step 38, based on the predicted acceleration α after the downshift is released and the inter-vehicle distance DS, referring to the safety judgment map shown in FIG.
One of the vigilance is determined. This safety judgment map is
When the inter-vehicle distance is a certain value, the determination result is set to be “safer” as the acceleration α is smaller. In addition,
As the determination factors, in addition to the acceleration α and the inter-vehicle distance DS, the vehicle speed の of the own vehicle, the relative speed with respect to the preceding vehicle, and the like may be added.

If an affirmative determination is made in step 24 following step 23, that is, if the reference result of the safety determination map is "safe", the process proceeds to step 25, in which the downshift instruction signal DOWN is changed from "1" level to "1". 0 "
Switch to level. At the same time, the deceleration execution flag FD
Reset S to "0". Shift down instruction signal DO
In response to the change in the level of WN, the downshift mode ends, and the shift control in the interrupted normal mode is resumed. As a result, acceleration is caused by upshifting, but safety from the viewpoint of the following distance can be ensured.

On the other hand, if a negative determination is made in step 24, that is, if the reference result from the safety determination map is "alert", the process proceeds to step 26, where the downshift instruction signal DOWN is set to the "1" level (downshift down). Instruction) and the deceleration execution flag FDS is maintained at "1". Therefore, the shift-down mode is not ended in this cycle, and this mode is continued until it is determined to be "safe" in the next cycle and thereafter. That is, when the inter-vehicle distance to be warned becomes due to the acceleration accompanying the upshift, the downshift mode is continued. Therefore, it is possible to prevent a situation in which the inter-vehicle distance is suddenly reduced, and thus it is possible to ensure safety in terms of the inter-vehicle distance.

As will be understood from the above description, when the downshift is to be released by passing through the curve, the microcomputer 1 evaluates the safety associated with the downshift release and then instructs the TCU 7 to release the downshift. Instructed. That is, it is determined whether it is safety or caution based on the acceleration caused by the upshift and the current inter-vehicle distance. If the result of the determination is "alert", the downshift is not released, and no acceleration due to the upshift occurs. The release of the downshift is suspended until the determination result changes to a state where the determination result is "safe" (or until the determination result changes to a state where the upshift does not occur).

As a result, it is possible to avoid a situation in which the inter-vehicle distance to the preceding vehicle is sharply reduced due to the shift-down release. Therefore, there is an effect that the safety and reliability of the vehicle behavior control according to the monitoring outside the vehicle can be further improved without giving the driver a feeling of anxiety.

In the above-described embodiment, the deceleration control in a situation where a curve is present in front of the own vehicle has been described. However, this deceleration control is performed in combination with the alarm control (to alert the driver). Is preferred. For example, if the current vehicle speed に 対 し て is too high with respect to a curve ahead, an alarm is first sounded to prompt the driver to decelerate. Then, when the driver does not perform deceleration by the brake operation or when the deceleration is insufficient, deceleration control by downshifting may be performed.

In the above-described embodiment, the deceleration control caused by the curve ahead of the vehicle has been described. However, the present invention is not limited to this, and can be widely applied to various driving situations where deceleration control can be performed. For example, the present invention may be applied to deceleration control in which a downshift is performed in accordance with a distance between the vehicle and a preceding vehicle. In this case, the determination inter-vehicle distance Dth is calculated according to the following equation instead of calculating the determination speed Vth in step 3 of FIG.

Dth = (current vehicle speedth [m / s] × idling time A [sec]
+ Margin B [m]) x (-(relative speed [m / s] x coefficient C + margin D)

Here, the relative speed is determined by the preview sensor 5
Can be calculated based on the change per unit time of the inter-vehicle distance from the preceding vehicle from the preview sensor information obtained from the above. When the current inter-vehicle distance becomes smaller than the determination inter-vehicle distance Dth, it is determined that the vehicle should be decelerated, and deceleration is performed by downshifting as described in the above-described embodiment.

[0053]

As described above, according to the present invention, when the downshift is canceled when the vehicle is no longer in a running condition to be decelerated, the situation in which the inter-vehicle distance is sharply reduced due to the occurrence of upshifting is considered. Can be avoided. Therefore, the safety and reliability of the device that controls the behavior of the vehicle according to the monitoring outside the vehicle can be further improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a transmission system using a downshift instruction device according to an embodiment;

FIG. 2 is a flowchart illustrating a main routine of a deceleration instruction according to the embodiment;

FIG. 3 is a flowchart showing the order of downshift release determination;

FIG. 4 is a flowchart showing a procedure of safety judgment.

FIG. 5 is a flowchart showing a procedure for estimating a road gradient;

FIG. 6 is a flowchart showing a shift control procedure.

FIG. 7 is an example of an engine torque calculation map;

FIG. 8 shows an example of a road gradient estimation map.

FIG. 9 shows an example of a shift map.

FIG. 10 shows an example of a safety judgment map.

FIG. 11 is an explanatory diagram of one curve constituted by a single node;

FIG. 12 is an explanatory diagram of one curve composed of a plurality of nodes;

FIG. 13 is a flowchart showing a procedure for calculating a determination speed.

[Explanation of symbols]

1 shift down instruction device (microcomputer),
2 vehicle speed sensor, 3 engine speed sensor, 4 throttle opening sensor,
5 preview sensor, 6 navigation unit, 7 transmission control unit (T
CU), 8 Hydraulic control circuit, 9
Automatic transmission (AT), 9a hydraulic control mechanism,
9b Friction engagement mechanism

Claims (7)

[Claims] 1. A shift-down instructing device for an automatic transmission, comprising: a recognizing means for recognizing a running condition ahead of a host vehicle based on preview information and calculating an inter-vehicle distance to a preceding vehicle ahead of the host vehicle; Instructing means for instructing a downshift when it is determined that the situation should be decelerated based on the recognition result in the recognizing means, and instructing cancellation of the downshift when it is determined that the situation should not be decelerated. When the instructing means determines that it is not possible to secure a safe inter-vehicle distance by releasing the downshift based on the inter-vehicle distance to the preceding vehicle calculated by the recognizing means, A downshift instructing device for an automatic transmission, wherein no instruction is given. When it is determined that a safe inter-vehicle distance cannot be secured by releasing the downshift, the instructing means issues an instruction to release the downshift until it is determined that a safe inter-vehicle distance can be secured. 2. The downshift instruction device for an automatic transmission according to claim 1, wherein the downshift instruction is held. 3. The control device according to claim 1, wherein the instruction means determines whether or not the vehicle is to be decelerated based on a curve existing in front of the vehicle and a vehicle speed of the vehicle.
A shift down instruction device for an automatic transmission according to claim 1. 4. The system according to claim 1, wherein the instruction means determines whether or not the vehicle is to be decelerated based on a positional relationship between the host vehicle and a preceding vehicle located in front of the host vehicle. Or the downshift instruction device for an automatic transmission according to item 2. 5. The instructing means determines whether downshifting can be canceled based on the predicted acceleration of the vehicle when the downshift is canceled and the inter-vehicle distance to the preceding vehicle calculated by the recognizing means. The downshift instruction device for an automatic transmission according to claim 1, wherein the determination is made. 6. A running resistance calculating means for calculating a running resistance of the own vehicle, wherein the instruction means determines whether or not the downshift can be canceled in consideration of the running resistance calculated by the running resistance calculating means. The downshift instruction device for an automatic transmission according to claim 5, wherein the determination is made. 7. A road gradient calculating means for calculating a road gradient at a position of the own vehicle, wherein the instruction means considers the road gradient calculated by the road gradient calculating means, and determines whether or not the own vehicle has been shifted down. 7. The downshift instruction device for an automatic transmission according to claim 5, wherein it is determined whether or not to accelerate.