JP3379641B2 - Downshift indicator for automatic transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a downshift instructing device for instructing downshifting of an automatic transmission according to a running condition in front of a vehicle, and in particular, downshifting is automatically performed when deceleration is required. The present invention relates to a shift-down cancellation determination performed later.

[0002]

2. Description of the Related Art There has been proposed a technique of grasping a traveling condition in front of a vehicle based on navigation information and preview information obtained from a preview sensor and, if necessary, performing deceleration by downshifting. For example, JP-A-8-20
In 2989 and Japanese Patent Laid-Open No. 8-194486, when the road ahead of the vehicle is curved, if it is determined that the vehicle speed when entering the curved road is too high, that is, it is overspeed, 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 good curve drivability without giving the driver a feeling of strangeness.

[0003]

By the way, when the vehicle is decelerated by downshifting and passes through a curve, the downshift mode is released, and the shift stage in the normal downshift mode is set. Since there are many cases in which shift up is automatically performed by returning to the normal mode, the vehicle starts to accelerate. At this time, if there is a preceding vehicle ahead of the own vehicle, there is a possibility that the distance between the preceding vehicle and the preceding vehicle may be sharply shortened due to the acceleration due to the shift-up.

The present invention has been made in view of the above problems, and an object thereof is to further improve the safety and reliability of a device for controlling the behavior of a vehicle in accordance with the outside of the vehicle.

[0005]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention relates to a shift-down instruction device for an automatic transmission, which recognizes a traveling condition in front of the vehicle based on preview information and at the same time Based on the recognition means for calculating the inter-vehicle distance to the preceding vehicle ahead and the recognition result in the recognition means, if it is determined that the situation is such that deceleration is required, downshifting is instructed When it judges, it has an instruction means for instructing to release the downshift. The instructing means is configured not to instruct to release the downshift if it is determined that the safe downhill distance cannot be secured by releasing the downshift based on the intervehicular distance to the preceding vehicle calculated by the recognizing means. Has been done.

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

Further, it is preferable that the instructing means determines whether or not the situation is such that the vehicle should be decelerated based on the curve existing in front of the vehicle and the vehicle speed of the vehicle.

Further, it is desirable that the instructing means determines whether or not the vehicle is in a decelerating condition based on the positional relationship between the vehicle and the preceding vehicle existing ahead of the vehicle.

On the other hand, the instructing means is provided after the shift down is released.
Based on the predicted acceleration of the vehicle caused by upshift and the inter-vehicle distance to the preceding vehicle calculated by the recognition means , the inter-vehicle distance is safe due to the acceleration accompanying up-shift.
Determining if you are going away or if you have to be on the lookout
By, it may be determined whether or not the release of the shift down.
At that time, it is preferable to further provide a traveling resistance calculating means for calculating the traveling resistance of the own vehicle, and determine whether or not the shift down can be released in consideration of the traveling resistance calculated by the traveling resistance calculating means. Further, a road gradient calculating means for calculating a road gradient at the vehicle position may be further provided, and in consideration of the road gradient calculated by the road gradient calculating means, it may be determined whether or not the vehicle accelerates after downshifting. desirable.

[0010]

FIG. 1 is a block diagram showing the overall configuration of a transmission system using a downshift instruction device according to this embodiment. The microcomputer 1 which is a shift-down instruction device includes a vehicle state signal (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 stage, which is information output from the transmission control unit (TCU) 7, is input. Based on these input information, the microcomputer 1 recognizes the traveling condition in front of the own vehicle, and instructs the TCU 7 to decelerate according to the recognition result.
WN and TRGT are output. When the 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 content (shift down mode).

FIG. 6 is a flow chart showing a shift control procedure performed in the TCU 7. First, in step 51, the TCU 7 makes the downshift instruction signal DOW.
N is read, and it is determined whether or not this instruction signal DOWN is at the "1" level, that is, whether or not the execution of downshift is instructed. In a normal traveling state, the downshift instruction signal DOWN is set to "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.
The gear GR is set based on the shift map based on the throttle opening θ. Then, the TCU 7 changes the gear position of the automatic transmission 9 (hereinafter referred to as AT) to the gear position GR.
The engagement control signal for setting to is output to the hydraulic control circuit 8 (step 54). The hydraulic pressure control circuit 8 operates the automatic transmission (AT) 9 in accordance with the instruction from the engagement control signal.
Each solenoid which comprises the inside hydraulic control mechanism 9a is operated. As a result, each frictional engagement element (clutch or brake) that constitutes the frictional engagement mechanism 9b in the AT 9 is engaged / released, and the AT 9 shifts to the shift speed (for example, 4 forward speeds, 1 reverse speed) instructed by the TCU 7. Is set.

On the other hand, the downshift instruction signal DO
When WN is at the "1" level, that is, when downshift execution is instructed (step 51), shift setting in the downshift mode is performed (step 5).
3). In this mode, the shift speed GR is forcibly set (that is, without referring 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
The U7 outputs an engagement control signal for setting the shift stage of the AT9 to the shift stage GR, that is, the target shift stage TRGT, to the hydraulic control circuit 8 (step 54).

The vehicle speed sensor 2, the engine speed sensor 3, and the throttle opening sensor 4 are 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 the traveling condition in front 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 picked-up images obtained from each CCD camera, it is possible to obtain three-dimensional position information including a distance to an object (preceding vehicle or road shape) existing ahead.
As the preview sensor 5, a monocular camera, a sensor using a millimeter wave or a laser wave, or a sensor using them in combination may be used instead of the stereo image processing device.

The navigation unit 6 is a CD-RO.
By using the road map information stored in the storage medium such as M or DVD and the GPS technology together, the navigation information including the position of the vehicle, the traveling direction, the road shape, etc. 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, recognizes the traveling situation in front of the vehicle). The information used directly for the vehicle) ensures the reliability of the recognition of the driving situation in front of the vehicle.

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

Next, the traveling condition in front of the vehicle is recognized based on the preview information and the navigation information (step 2). Specifically, the three-dimensional road shape, the presence / 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 point to be recognized in relation to this embodiment is detection of a curve existing in front. As a pattern forming one curve, there are a case where the curve is composed of a single node as shown in FIG. 11 and a case where the curve is composed of a plurality of nodes as shown in FIG. Information about these nodes can be obtained from the navigation information, and includes coordinate information of discrete points on the road with respect to the host vehicle. The road shape is expressed as a polygonal line by a line segment connecting adjacent nodes.

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

(Same curve condition) 1. 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, Pj,
The sign of t [j] is the same

Here, the inter-node distance L [j] of the node Pj is calculated by the following equation.

## EQU1 ## 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 condition as described above, it is determined that the nodes P1, Pj-1, Pj, Pj + 1 shown in FIG. 11 form different curves. In addition, the node groups Pj-1 to Pj + 2 shown in FIG. 12 are determined to form one curve.

In step 3 following step 2, the determination speed Vth corresponding to the curve shape in front is calculated. The determination speed Vth indicates the upper limit value of the vehicle speed that is allowed in the current position of the own vehicle in relation to the curve shape in the front, and the deceleration determination in step 5 (whether shift down is possible or not).
It is used as a judgment threshold value when performing. Figure 13
6 is a flowchart showing a detailed calculation procedure of a determination speed Vth in step 3.

First, the road surface friction coefficient μ (hereinafter referred to as road surface μ
And the road slope SL are 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, as disclosed in, for example, Japanese Patent Laid-Open No. 8-2274. The method of calculating the road slope SL will be described later.

In step 13 following step 12, the maximum value of deceleration at which slip does not occur on a certain road surface μ, that is, the allowable deceleration β is calculated. The permissible 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
Japanese Patent Application Laid-Open No. 11-8350
Since it is disclosed in Japanese Patent Publication No. 1, reference should be made if necessary.

Then, with respect to the front curve specified in the above step 2, its target node P
Allowable approach speed Vap of trgt and target node Ptrgt
Is calculated (step 14). Here, the "target node Ptrgt" means a node having the smallest curve curvature radius in one curve. The vehicle speed that can be permitted when entering a certain curve existing in front of the host vehicle may be set based on the node that should be decelerated most because it has the smallest radius of curvature. Therefore, in the road shape shown in FIG. 11, each node P1, Pj-1, which forms a separate curve,
Pj and Pj + 1 are the target nodes Ptrgt, respectively.
Further, in the road shape shown in FIG. 12, of the node groups Pj-1 to Pj + 2 forming one curve, the node Pj-1 having the smallest radius of curvature becomes the target node Ptrgt in that curve. The curve curvature radius 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 that.

Based on the specified curvature radius of the target node Ptrgt, the approach speed Vap allowed to pass through the target node Ptrgt is calculated by the following method. First, the allowable lateral acceleration gv is calculated before calculating the allowable approach speed Vap. When passing through a curve, the smaller the road surface μ, the smaller the limit value of lateral acceleration. Further, 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. The detailed calculation method of the allowable lateral acceleration gv is disclosed in Japanese Patent Laid-Open No. 11-83501, so refer to it if necessary.

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

[Equation 3] Vap = (gv × rtrgt) ^1/2

Note that this value may be corrected according to the depth of the curve and the road width, and the corrected value may be used as the allowable approach speed Vap. In this case, the larger the curve depth or the narrower the road width, the smaller the allowable approach speed Vap.

In step 15 following step 14, the allowable approach speed Vap at the target node Ptrgt is set.
From this, the determination speed Vth indicating the upper limit of the vehicle speed at the current position of the 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 decelerated by K% (for example, 50%) of the allowable deceleration β. It is a speed such that the vehicle speed sometimes becomes the allowable approach speed Vap. As an example, the determination speed Vth can be obtained by the following formula.

[Equation 4] Vth = (Vap ² ) + 2 × (K × β) L) ^1/2

Thus, the allowable approach speed Vap for the curve ahead and the distance L to the target node Ptrgt
If 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, in step 5 to be described later, by comparing the vehicle speed υ at the current position with the determination speed Vth, it is determined whether or not the vehicle speed υ is excessive with respect to the entry of the curve, that is, the necessity of deceleration.

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, when the flag FDS is "0", the process proceeds from step 4 to step 5.

In step 5 following step 4, it is judged whether or not the situation is such that deceleration is required. 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 υ is equal to or lower than the determination speed Vth, it is determined that it is possible to enter the curve ahead at the current vehicle speed υ without decelerating. Therefore, in this case, the negative determination in step 5 proceeds to steps 9 and 11, and the downshift instruction signal DOWN of "0" level is output to the TCU 7. The shift-down instruction signal DOWN is normally set to the “0” level (instructing the shift control in the normal mode) except in a special traveling situation in which automatic deceleration is required. Upon receiving the downshift instruction signal DOWN of "0" level, the TCU 7 performs the shift control in the normal mode (step 52).

On the other hand, if the affirmative determination is made in step 5, that is, if the vehicle speed υ is larger than the determination speed Vth, it is determined that the current vehicle speed υ is excessive in order to safely enter the curve ahead. To do. In this case, it is determined that deceleration is necessary, and the process proceeds to steps 6 and 11, and the microcomputer 1 instructs the TCU 7 to downshift in order to decelerate before entering the curve. Specifically, the downshift instruction signal DOWN becomes "1" level, and the deceleration execution flag FDS is set at "1" level. Further, the target shift speed TRGT after the downshift is set. The target shift speed TRGT sets a shift speed that is one paragraph from the current shift speed (for example, if the current shift speed is the fourth speed, the third speed) in all ranges including the D range. Further, in the D range and when the current gear stage is the fourth gear (or the third gear), the third gear (or the second gear) may be set as the target gear stage TRGT. In addition, depending on the degree of deceleration required, one or two gears from the current gear
The gear position set as a paragraph may be set as the target gear position TRGT. Also, a method of changing the shift mode itself is possible. For example, if the current shift mode is the D range, it may be lowered to the 3 range.

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, the procedure for releasing the deceleration instruction will be described. When the shift down is instructed to be executed 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 in which deceleration is to be achieved has disappeared. This determination is made based on the passage of a curve including the target node Ptrgt, the traveling state of the vehicle, and the like. If a negative decision is made in step 7 (for example,
If you haven't passed the curve yet), go to step 10,
11, the shift down instruction signal DO of "1" level
WN is output to TCU7. Therefore, the shift down mode is not released, so that the gear position of AT9 is maintained at the target gear position TRGT (that is, the down shift state is maintained). The shift-down instruction signal DOWN is kept at "1" level until the deceleration is no longer necessary, so that the normal mode is not restored.

On the other hand, when the situation in which deceleration is not necessary is eliminated,
In that cycle, the process proceeds from step 7 to step 8 and it is determined whether or not the shift down can be released. If it is determined from the determination result in step 8 that the shift down may be released, the shift down instruction signal DOW
N is switched from the "1" level to the "0" level, and the deceleration execution flag FDS is also reset to "0".
As a result, the downshift control returns 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 canceled, the downshift instruction signal DOWN remains at "1" level and the deceleration execution flag FD is set.
S is also maintained at "1". As a result, in this cycle, the downshift mode is continued without restarting the normal mode (step 53 in FIG. 6).

FIG. 3 is a flow chart showing a detailed procedure of shift down cancellation determination. First, step 21
At, it is determined from the recognition result based on the preview information whether or not a preceding vehicle is present on the traveling path in front of the vehicle (within a predetermined monitoring distance range). If there is no preceding vehicle, there is no need to consider the inter-vehicle distance after releasing the downshift. Therefore, in this case, the routine 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 restarts the shift control in the interrupted normal mode.
In other words, when there is no preceding vehicle, the shift control in the normal mode is restarted immediately when the driving condition for deceleration is lost. Usually, this often results in an upshift.

On the other hand, if the affirmative determination is made in step 21, that is, if there is a preceding vehicle, it is safe not to immediately return to the normal mode but to accelerate due to a shift-up from the distance between the preceding vehicle. Only if it is determined that Therefore, 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 or not it is safe to cancel the downshift (step 23). FIG. 4 is a flowchart showing a detailed procedure of safety judgment.

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 the planned shift stage signal in the normal mode) , Target gear TR
Identified as GT. Next, it is determined from the reference result of the shift map whether or not the shift up occurs after the shift up is released (step 32). If the shift-up does not occur even if the shift-down is released, the distance between the preceding vehicle and the preceding vehicle does not suddenly decrease, so there is no problem in restarting the normal mode immediately. 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". This allows TCU
7 finishes the shift down mode and restarts the shift control in the normal mode.

On the other hand, if the affirmative determination is made in step 32, that is, if the shift up occurs after the shift down is released, the process proceeds to step 33. This step 32
7, based on the current engine speed NE calculated from the sensor 3 and the current throttle opening θ calculated from the sensor 4, referring to the engine torque calculation map shown in FIG. Tq is calculated. Then, at step 34, the predicted driving force F after upshifting is calculated from the current output torque Tq and the gear ratio Rtrgt of the target shift stage TRGT based on the following equation. In the equation, Rfinal is the final gear ratio (constant) and C is the 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 backward in the air, is calculated from the current vehicle speed υ calculated from the sensor 2 by the following equation. Here, the constant A is the overall projected area, the constant Cd is the air resistance coefficient, and the constant ρ is the air density.

[Equation 6] r = A × Cd × 1 / 2ρ × υ ²

Then, in step 36, the road gradient SL is calculated on the basis of the current vehicle speed υ and the current generated driving force F (note that it is the driving force in the gear stage 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 shift stage P is
Current output torque Tq calculated in step 22
And the current gear ratio R of the shift stage P are calculated by the same calculation formula as the above-mentioned formula 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. . Road slope estimation map is
It shows changes in the generated driving force F with respect to the vehicle speed υ 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.

In step 37 following step 36, the target is calculated from the predicted driving force F [N] (driving force at the target shift speed TRGT after releasing the downshift), the running resistance r [N], and the road gradient SL [degree]. The acceleration α of the shift speed TRGT (predicted acceleration after release of downshift) is calculated by the following formula. The constant g in the equation is the gravitational acceleration.

[Formula 7] α = F / W- (r / W-g × sin SL)

Then, in step 38, based on the predicted acceleration α after the shift down is released and the inter-vehicle distance DS, referring to the safety judgment map shown in FIG.
Any of the vigilance is judged. This safety judgment map is
When the inter-vehicle distance has a certain value, the smaller the acceleration α is, the more “safe” the determination result is set. In addition,
In addition to the acceleration α and the inter-vehicle distance DS, the vehicle speed υ of the own vehicle, the relative speed to the preceding vehicle, and the like may be taken into consideration as the determination factors.

If a positive 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" level. 0 "
Switch to level. Along with that, deceleration execution flag FD
Reset S to "0". Downshift instruction signal DO
In response to the change in the level of WN, the shift down mode ends, and the shift control in the interrupted normal mode is restarted. As a result, acceleration is generated as a result of shifting up, but it is possible to ensure safety from the viewpoint of the inter-vehicle distance.

On the other hand, if a negative determination is made in step 24, that is, if the result of reference by the safety determination map is "warning", the routine proceeds to step 26, where the shift down instruction signal DOWN is at the "1" level (shift down). Instruction), and the deceleration execution flag FDS is maintained at "1". Therefore, the shift down mode does not end in this cycle, and this mode continues until the next cycle or later is judged as "safe". In other words, if the inter-vehicle distance becomes alarming due to the acceleration accompanying the shift up, the downshift mode is continued. Therefore, it is possible to prevent a situation in which the inter-vehicle distance is sharply shortened, and it is possible to ensure safety in terms of the inter-vehicle distance.

As can be seen from the above description, when the shift down is released by passing the curve, the microcomputer 1 evaluates the safety accompanying the release of the down shift and then releases the down shift to the TCU 7. To instruct. That is, it is determined whether the vehicle is safe or vigilant based on the acceleration generated by the shift-up and the current inter-vehicle distance. When the determination result is "warning", the downshift is not released, and therefore the upshift does not cause acceleration. The release of the shift-down is suspended until the determination result changes to a state of "safety" (or the state where the shift-up does not occur).

As a result, it is possible to avoid the situation in which the inter-vehicle distance to the preceding vehicle is suddenly shortened due to the release of the downshift. Therefore, there is an effect that the driver's anxiety is not given and the safety and reliability of the vehicle behavior control according to the vehicle exterior monitoring can be further improved.

In the above embodiment, the deceleration control in the situation where there is a curve ahead of the vehicle has been described, but this deceleration control is performed in combination with the alarm control (calling attention to the driver). It is preferable. For example, if the current vehicle speed υ is excessive with respect to the curve ahead, an alarm is first sounded to prompt the driver to decelerate. Then, when the driver does not decelerate by the brake operation or when the deceleration is insufficient, the deceleration control by downshifting may be performed.

Further, the above-described embodiment has explained the deceleration control caused by the curve in front of the vehicle. However, the present invention is not limited to this, and can be widely applied to various traveling situations in which deceleration control can be performed. For example, it may be applied to deceleration control in which downshifting is performed according to the inter-vehicle distance from the preceding vehicle. In this case, instead of calculating the determination speed Vth in step 3 of FIG. 2, the determination inter-vehicle distance Dth is calculated according to the following equation.

[Equation 8] Dth = (current vehicle speed υ [m / s] x idle 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
From the preview sensor information obtained from the above, it can be calculated based on the change in the inter-vehicle distance with the preceding vehicle per unit time. Then, when the current inter-vehicle distance becomes smaller than the determined inter-vehicle distance Dth, it is determined that deceleration is required, 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 driving condition to be decelerated is lost, the inter-vehicle distance is suddenly shortened due to the upshift. Can be avoided. Therefore, it is possible to further improve the safety and reliability of the device that controls the behavior of the vehicle according to the vehicle exterior monitoring.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a main routine of a deceleration instruction according to the present embodiment.

FIG. 3 is a flowchart showing the order of shift down cancellation determination.

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

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

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

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

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

FIG. 9 is an example of a shift map

FIG. 10 An example of a safety judgment map

FIG. 11 is an explanatory diagram of one curve composed of a single node.

FIG. 12 is an explanatory diagram of one curve composed of multiple nodes.

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

[Explanation of symbols]

1 Downshift 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

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Claims (7)

(57) [Claims] 1. A downshift instructing device for an automatic transmission, which recognizes a traveling condition in front of the own vehicle based on the preview information and calculates an inter-vehicle distance to a preceding vehicle ahead of the own vehicle, Based on the recognition result by the recognizing means, when it is determined that a deceleration condition is reached, a downshift is instructed, and when it is determined that the deceleration condition is not reached, an instructing device is instructed to cancel the downshift. When the instruction means determines that a 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 means, the downshift is released. A downshift instruction device for an automatic transmission characterized by not giving an instruction. 2. If the instructing means determines that a safe inter-vehicle distance cannot be secured by releasing the shift-down, the instructing means issues an instruction to release the down-shift until it is determined that a safe inter-vehicle distance can be secured. The shift-down instruction device for an automatic transmission according to claim 1, wherein the shift-down instruction device holds. 3. The method according to claim 1, wherein the instructing means determines whether or not the vehicle should be decelerated based on a curve existing in front of the vehicle and the vehicle speed of the vehicle.
The downshift instruction device for an automatic transmission described in 1. 4. The instructing means determines whether or not the vehicle is in a decelerating condition based on the positional relationship between the vehicle and a preceding vehicle existing ahead of the vehicle. Alternatively, the downshift instruction device for an automatic transmission described in 2. 5. The instruction means is a system after the shift down is released.
Based on the predicted acceleration of the own vehicle caused by the upshift and the inter-vehicle distance to the preceding vehicle calculated by the recognition means , the inter-vehicle distance is safe due to the acceleration accompanying the upshift.
To determine whether it is a distance or an inter-vehicle distance that requires caution .
And the downshift instruction device for an automatic transmission as claimed in claim 1, characterized in that to determine whether the release of the downshift. 6. The vehicle further comprises a traveling resistance calculating means for calculating a traveling resistance of the own vehicle, wherein the instructing means considers the traveling resistance calculated by the traveling resistance calculating means to determine whether or not the shift down can be released. The shift-down 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 vehicle position is further provided, wherein the instructing means considers the road gradient calculated by the road gradient calculating means, The shift-down instruction device for an automatic transmission according to claim 5 or 6, wherein it is determined whether or not to accelerate.