JP3606048B2 - Shift control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for an automatic transmission.
[0002]
[Prior art]
In general, a manual transmission of a vehicle in which the weight (load) fluctuates greatly, such as a tractor towing a trailer or a large truck, is provided with a sub-transmission for switching the gear position between a high speed side and a low speed side. Yes.
For example, when the load is high, such as when loading a load, the auxiliary transmission can be switched to the low speed stage to increase the drive torque transmitted to the drive wheels. At such a low load, the fuel efficiency can be improved by switching the auxiliary transmission to the high speed side.
[0003]
In such a transmission with a sub-transmission, if the transmission body has five forward speeds and one reverse speed, the forward 10 speeds (5 speeds × 2) and the reverse 2 speeds (1 In this case, the transmission with the auxiliary transmission is also referred to as a multi-stage transmission.
On the other hand, a mechanical automatic transmission has been developed in which an actuator for automatically connecting and disconnecting a clutch is attached to such a manual transmission so that a gear can be shifted without stepping on the clutch pedal.
[0004]
Such a mechanical automatic transmission is provided with a clutch actuator for connecting / disconnecting the clutch and a gear shift unit (gear shift actuator) for switching the meshing state of the gear mechanism of the transmission, and the engine speed. The adjustment is performed by the electronic governor in the injection pump, and the shift operation is performed by controlling the operation of the clutch actuator, the gear shift actuator and the electronic governor based on the command signal from the control means (controller) of the automatic transmission. Configured to do.
[0005]
Furthermore, a technique has been proposed in which fuzzy control is applied to the mechanical automatic transmission as described above to correct the target shift stage set in the shift map in accordance with the driver's intention and the load state of the vehicle. (JP-A-9-79364).
[0006]
[Problems to be solved by the invention]
By the way, in vehicles such as tractors and large trucks, it is necessary to use a step shift (shift by one step) and a skip shift (shift by one step) depending on the load of the vehicle. Here, the skip shift is a shift mode in which shift control is performed with a shift pattern such as 1H-2H-3H-4H-5H, and the step shift is 1L-1H-2L-2H-3L-3H. This is a shift mode in which shift control is performed with a shift pattern such as -4L-4H-5L-5H. The numerals indicate the gear stage of the main transmission, and the letters after the numerals indicate the gear stage of the sub-transmission (H is the high speed stage and L is the low speed stage).
[0007]
However, when the conventional mechanical automatic transmission technology is applied to such a multi-stage transmission, there is a problem that a changeover switch for switching between step shift and skip shift is required.
Therefore, it is conceivable to eliminate the changeover switch and perform a shift by only one of the step shift and the skip shift. For example, when the automatic shift is set by only the step shift, Depending on the load state of the vehicle, there is a possibility that the target gear stage is set to the high speed side one after the other at the time of acceleration, and a plurality of upshifts (for example, 2H → 3L → 3H) are executed in a short time. Yes (especially when the vehicle is empty), which may lead to deterioration of drivability.
[0008]
Further, when the automatic shift is performed only by the skip shift, depending on the load state of the vehicle, even if it is desirable to shift from 2H to 3L (particularly during loading), from 2H to 3H. There is a problem that drivability is not good.
In Japanese Patent Laid-Open No. 9-79364 described above, the target shift speed is corrected by fuzzy control, but the shift control is not performed by properly using such step shift and skip shift.
[0009]
The present invention has been devised in view of such problems, and automatically shifts between step shift and skip shift according to the state of the vehicle, and eliminates the conventional manual changeover switch. An object of the present invention is to provide a shift control device for a machine.
[0010]
[Means for Solving the Problems]
In the shift control device for an automatic transmission according to the first aspect of the present invention, the target shift stage according to the driving state of the vehicle is set by the target shift stage setting means based on the detection information from the vehicle speed detection means and the accelerator opening detection means. In addition to being set, the gear stage of the transmission is changed by the gear stage control means in accordance with the output from the target gear stage setting means.
Further, the vehicle load detection means calculates the difference between the acceleration when the vehicle is accelerating on the straight flat road in an empty state and the actual acceleration when the vehicle is actually accelerated as the load degree of the vehicle.
[0011]
When the target shift speed setting means sets the first shift up, the vehicle load degree calculated by the vehicle load degree calculation means is substantially zero, and the vehicle accelerator opening detected by the accelerator opening detection means is detected. If the degree is large, a plurality of shift-up instructions are output from the shift speed correction means to the shift speed control means in preference to the output from the target shift speed setting means. As a result, upshifting by one stage is not continuously performed a plurality of times in a short time, and drivability is improved.
[0012]
According to a second aspect of the present invention, the accelerator opening change rate calculating means calculates the accelerator opening change rate based on the accelerator opening detected by the accelerator opening detecting means. Is done. In the gear position correcting means, when the first gear shift down is set by the target gear position setting means, the vehicle load degree is substantially zero, the accelerator opening is large, and the accelerator opening change rate is substantially the same. If it is zero, the current gear position maintaining instruction is output from the gear position correction means to the gear position control means in preference to the output of the target gear position setting means.
[0013]
Therefore, even if a shift stage is set to a lower speed side than the shift stage by the target shift stage setting means after being shifted up by a plurality of stages, a downshift is not executed and drivability is not impaired.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a shift control apparatus for an automatic transmission according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of the main part, and FIG. 2 is a diagram showing a fuzzy rule. .
In the present embodiment, a case will be described in which a mechanical automatic transmission adapted to perform automatic shifting using a gear mechanism similar to a manual transmission is applied as an automatic transmission. Further, this mechanical automatic transmission is the same as that described in the above-mentioned prior art, and the description of the detailed configuration is omitted.
[0015]
Further, this automatic transmission is composed of a main transmission and a sub-transmission attached to the main transmission, similarly to the above-described prior art, and has 10 forward speeds (5 speeds × 2), It has two reverse gear stages (1 stage x 2). The shift speeds are not expressed as 1L, 1H, 2L,..., But are simply expressed as 1st speed, 2nd speed,.
[0016]
As shown in FIG. 1, the shift control device for an automatic transmission according to the present invention shifts to an optimum shift stage that reflects the driver's intention using fuzzy theory. Further, the operation of the automatic transmission is controlled by the control unit 71, and the optimum gear stage is set by the control unit 71.
[0017]
In the control unit 71, a target shift that sets a target shift stage based on the vehicle speed information V from the vehicle speed sensor (vehicle speed detecting means) 79 and the accelerator opening information VA from the accelerator opening sensor (accelerator opening detecting means) 85. A stage setting means 3 and an optimum speed stage determining means (speed stage control means) 1 for determining the optimum speed stage reflecting the driver's intention are provided.
[0018]
Here, the optimum gear stage determining means 1 uses a fuzzy theory to determine the driver's intention and the running state of the vehicle, and to change the target gear stage set by the target gear stage setting means 3. It is comprised as a stage determination means.
The target shift speed setting means 3 is widely used in ordinary automatic transmissions, and here, as a shift map in which shift-up shift characteristics and shift-down shift characteristics for 10 stages are stored. The target gear position is set based on the accelerator opening information VA detected by the accelerator opening sensor 85 and the vehicle speed information V detected by the vehicle speed sensor 79.
[0019]
On the other hand, the optimum gear stage determining means 1 applies driving information having vehicle load information as a parameter to the fuzzy rule, and this vehicle load information is obtained when the vehicle accelerates on a straight flat road in an empty state. Acceleration α₀  And the actual acceleration α when the vehicle is actually accelerated (= vehicle load α_VL) Is used as a parameter.
[0020]
Therefore, as shown in FIG. 1, the control unit 71 includes the vehicle load degree α._VLVehicle load degree calculation means 2 is provided for calculating. The vehicle load degree α by the vehicle load degree calculating means 2_VLThe calculation method is substantially the same as that described in JP-A-9-79364. Hereinafter, the vehicle load degree α will be simply described._VLThe calculation method of will be described.
[0021]
The vehicle load degree calculating means 2 includes an engine torque calculating means 4, a driving force calculating means 5, an air resistance calculating means 6, a straight flat road empty vehicle equivalent acceleration calculating means 7, and a subtracting means 8.
Among these, the engine torque calculation means 4 calculates an output torque T of the engine (here, a diesel engine). As shown in FIG. 1, the position information (engine output) of the control rack from the rack position sensor 23 is calculated. Instruction information) Based on the SRC and the engine speed information NE from the engine speed sensor 27, the output engine torque T is calculated.
[0022]
The driving force calculation means 5 calculates the driving force F of the vehicle based on the engine torque information T obtained by the engine torque calculation means 4. The air resistance calculation means 6 is a vehicle speed sensor 79. The air resistance Rl as the running resistance of the vehicle is calculated from the detected actual vehicle speed information V.
Further, the straight flat road empty vehicle equivalent acceleration calculating means (hereinafter sometimes simply referred to as acceleration calculating means) 7 includes driving force information F calculated by the driving force calculating means 5 and air calculated by the air resistance calculating means 6. From the resistance information Rl, acceleration when the vehicle accelerates on a straight flat road in an empty state (hereinafter referred to as a straight flat road empty vehicle equivalent acceleration) α₀  Is calculated.
[0023]
Then, in the subtracting means 8, the straight flat road empty vehicle equivalent acceleration information α calculated by the acceleration calculating means 7.₀  Vehicle load degree information α based on the actual acceleration information α from the vehicle speed sensor 79._VLIs calculated by the following equation.
α_VL= Α₀  -Α
And this α_VLIt is determined how heavy (or light) the vehicle load is from the magnitude of the value of.
[0024]
Further, as shown in FIG. 1, the controller 71 is provided with accelerator opening change rate calculating means 9 for calculating the accelerator opening change rate ΔVA from the accelerator opening information VA detected by the accelerator opening sensor 85. As described above, the vehicle load degree α is calculated by the vehicle load degree calculation means 2._VLIs calculated, the optimum gear position determining means 1 calculates the vehicle load degree α._VLIn addition to the information on the accelerator position information VA, the accelerator position change information ΔVA, the vehicle speed information V, the current speed information, and the like, the target speed set by the target speed setting means 3 is obtained. Correction is made.
[0025]
The optimum gear stage determining means 1 corrects the target gear stage by fuzzy inference from each information based on a predetermined fuzzy rule. That is, even if the target shift speed obtained from the shift map (that is, the shift speed set by the target shift speed setting means 3) is different from the current shift speed, the optimum shift speed determination means 1 intends to shift to the driver. If it is estimated that there is not so much, a control signal is issued so as to maintain the current shift speed, or the driver wants to shift down even if the current shift speed matches the target shift speed. If it is estimated that the control signal is present, the control signal is output so as to execute the downshift.
[0026]
Next, the main part of the present invention will be described. As shown in FIG. 1, the optimum gear stage determining means 1 has a plurality of stages in the optimum gear stage determining means 1 in preference to the output from the target gear stage setting means 3. There is provided gear position correction means 1a for instructing the upshift.
In the present invention, in addition to the conventional fuzzy rule, two fuzzy rules R as shown in FIG.₁, R₂Is set, the upshift is set on the shift map, and the state of the vehicle is fuzzy rule R₁If it is suitable, the shift speed correcting means 1a executes a shift-up (referred to as a jump shift or a skip shift) of a plurality of stages (here, two stages) in preference to the output from the target shift speed setting means 3. A control signal is output to the optimum gear position determining means 1. In addition, when the upshift is set on the shift map, the fuzzy rule R₁If it is not suitable, the shift is shifted up (step shift) to the target shift stage (current stage + 1 stage) set in the shift map, as in normal shift control.
[0027]
Also, fuzzy rule R₂If it is suitable, the shift speed correction means 1a gives priority to the shift control to the target shift speed set by the target shift speed setting means 3, and the fuzzy rule R₁A signal for holding the gear position after the skip shift executed by the above is output to the optimum gear stage determining means 1 to prevent an unintentional shift down after the skip shift.
[0028]
Here, first fuzzy rule R₁The concept of vehicle load α_VLIs substantially zero, the accelerator opening VA is large, and the shift map shift-up line has been exceeded (that is, the shift stage on the first high speed side is set as the target shift stage by the target shift stage setting means 3). Therefore, the gear position correcting means 1a estimates that a further target gear position will be set in a short time and a plurality of upshifts will be executed continuously. In this case, the shift speed correction means 1a controls the shift speed so that the shift speed is further shifted up to another shift speed in preference to the shift speed up to the target shift speed set by the target shift speed setting means 3. A signal is issued, and thereby a shift shift (skip shift) of the gear stage is executed. Therefore, such fuzzy rule R₁In such a case, a situation in which upshifts are continuously executed in a short time is avoided, and the number of shifts is reduced as compared with the conventional case, thereby improving drivability.
[0029]
Further, when the upshift is set on the shift map, the fuzzy rule R described above is used.₁If the antecedent part is not established, a shift up (step shift) for the first speed is executed as usual. It should be noted that the fuzzy rule R input to the optimum gear stage determining means 1 as a parameter of driving information₁Information about α_VL, VA membership function and fuzzy rule R described later₂Information about α_VL, VA, ΔVA, NE membership functions and membership functions of each consequent part are not described here.
[0030]
Here, the reason why the skip shift and the step shift are properly used as described above is mainly due to the following reasons.
That is, in the multi-speed transmission having 10 speeds as in the present embodiment, the up-shift line on the shift map is close, and depending on the vehicle load status and accelerator operation status, In some cases, the target gears may be set to the higher gear side one after another. However, when gear shifting control is actually performed in accordance with such target gears, continuous upshifts are executed in a short time. This is because drivability may be impaired.
[0031]
In such a case, depending on the vehicle load condition, etc., for example, a shift shift (skip shift) if the vehicle load is small, and a shift for each step (step shift) if the vehicle load is large. It is desirable to change the method automatically.
Therefore, in the shift control device for an automatic transmission according to the present invention, as described above, whether or not the skip shift should be performed is estimated from the vehicle load degree and the accelerator opening degree by fuzzy theory.
[0032]
In the present embodiment, the skip shift as described above is executed only when the current shift speed is between the third speed and the eighth speed, and is not executed otherwise. This is because if the skip shift is performed at the first gear or the second gear, the shift shock may increase, which may lead to deterioration of drivability. Therefore, skip shift is not executed at such a low speed stage. The reason why the skip shift is not executed at the 9th speed or more is that, in the present embodiment, a multi-stage transmission having 10 shift stages is applied as the automatic transmission, and the skip shift is applied to 8 This is because the speed is the upper limit. Of course, when the skip shift is set to skip two steps (for example, when skipping to the target shift step + two steps based on the shift map), the seventh speed is the upper limit of the skip shift.
[0033]
Next, fuzzy rule R₂The fuzzy rule R described above will be explained.₁Immediately after the multiple-step skip shift is executed, the target shift stage based on the shift map and the shift stage after the skip shift normally coincide with each other, but the target shift stage based on the shift map is shifted after the skip shift. If the speed is lower than the stage, it is considered that downshifting is executed after skip shift against the driver's intention, and the fuzzy rule R is used to prevent this.₂Is provided.
[0034]
For example, fuzzy rule R₁When the gear shift was shifted from 3rd gear to 5th gear, but actually crossed the shift-up line more slowly than fuzzy reasoning. Therefore, the first-stage downshift is prevented from being executed after the skip shift, and the fifth speed is maintained and the process waits for the fifth speed on the shift map.
[0035]
Therefore, vehicle load degree α_VL> 0, the value is small or substantially zero, the accelerator opening VA is large, the accelerator opening change rate ΔVA is substantially zero, the engine speed NE is medium, and the downshift is indicated in the shift map. (That is, when the target gear position is set by the target gear position setting means 3 as a target gear position one speed lower than the current gear position), the gear position correcting means 1a shifts down the shift map. Prior to the instruction signal, a control signal is issued so as to maintain the current gear position. In other words, in this case, the gear position correction means 1a estimates that the driving state of the vehicle has not yet caught up with the gear position after the skip shift, but will be in the driving state corresponding to the current gear position in a short time thereafter. Thus, the control signal is output so as to maintain the current gear position.
[0036]
Therefore, such fuzzy rule R₂By providing this, the shift down immediately after the skip shift is prevented, and the deterioration of drivability can be prevented.
The fuzzy rule R described above₂Then, although the engine speed information is taken in, this engine speed information is not an essential condition, and the engine speed information may not be taken into consideration. In addition, the fuzzy rule R described above₂In addition, a situation in which a downshift is instructed based on the shift map immediately after the skip shift may be converted into a fuzzy rule to prevent the downshift immediately after the skip shift.
[0037]
The shift control device for an automatic transmission according to an embodiment of the present invention is configured as described above. In the control unit 71, the optimum shift stage is set as follows.
First, the engine torque T is calculated by the engine torque calculation means 4 based on the position information SRC of the control rack and the engine speed information NE. Next, the driving force is calculated based on the engine torque T obtained by the engine torque calculating means 4, the gear ratio it, the final reduction gear ratio (final reduction gear ratio) if, the power transmission efficiency η, and the tire dynamic radius R. The means 5 calculates the driving force F of the vehicle.
[0038]
The air resistance calculation means 6 calculates the air resistance Rl of the vehicle based on the air resistance coefficient λ, the front projection area A of the vehicle, and the vehicle speed V.
Then, the straight flat road empty vehicle equivalent acceleration calculating means 7 calculates the straight flat road empty vehicle equivalent acceleration α from the driving force F and the air resistance information Rl.₀  And the straight flat road empty vehicle equivalent acceleration information α₀  Vehicle load degree information α based on the actual acceleration information α from the vehicle speed sensor 79._VLIs calculated.
[0039]
Next, the optimum gear stage determining means 1 determines the vehicle load degree α calculated as described above._VLIn addition, based on information from each sensor, the driving state of the vehicle is estimated and the driver's driving intention is estimated.
On the other hand, in the target shift speed setting means 3, the target shift speed is set from the shift map according to the running state based on the vehicle speed V and the accelerator opening VA, as in the normal shift.
[0040]
Then, the target shift speed is compared with the driver intention estimated as described above, and a correction signal for correcting the shift command to the target shift speed is set. As a result, an optimum shift speed that reflects the driver's intention with respect to the target shift speed is set.
In particular, in the present invention, when the target shift speed = the current shift speed + 1 stage is set by the target shift speed setting means 3, the vehicle load degree α_VLIs substantially zero and the accelerator opening VA is large, the gear position correction means 1a sets a further target gear position in the short time and executes multiple upshifts in succession in the future. Assuming that this is done, a shift-up (skip shift) is executed to a shift stage that is one step higher than the shift-up to the target shift stage set by the target shift stage setting means 3.
[0041]
Therefore, it is possible to avoid a situation in which up-shifting is continuously performed a plurality of times in a short time, and the number of shifts is reduced as compared with the conventional case, thereby improving drivability.
Further, when the target shift speed = the current shift speed + 1 stage is set by the target shift speed setting means 3, if the above-described skip shift condition is not satisfied, the shift up (step shift) for the first speed is performed as usual. Executed.
[0042]
Therefore, a skip shift is executed when the vehicle load is small, and a step shift is executed when the vehicle load is large. Therefore, the skip shift and the step shift are automatically switched according to the vehicle load condition. It is done. This eliminates the need for a changeover switch for switching between step shift and skip shift, and enables further easy driving.
[0043]
Further, after the skip shift is performed as described above, when the downshift is instructed because the driving state of the vehicle does not correspond to this shift stage on the shift map, the vehicle load degree α_VLIf the value is> 0, the value is small or substantially zero, the accelerator opening VA is large, the accelerator opening change rate ΔVA is substantially zero, and the engine speed is medium, a shift down instruction in the shift map The current gear position is maintained in preference to.
[0044]
In other words, in this case, the gear position correcting means 1a estimates that the driving state of the vehicle has not yet caught up with the gear position after the skip shift, but will be in the driving state corresponding to the current gear position in a short time thereafter. Thus, the current gear position is maintained. Therefore, the downshift immediately after the skip shift is prevented, and the skip shift can be executed reliably.
[0045]
The shift control device for an automatic transmission according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Further, although the shift speed of the automatic transmission is not limited to the 10 speeds as described above, this device is particularly useful for a multi-speed transmission in which the upshift lines on the shift map are close to each other. It is. Specifically, it can be said that it is suitable for use in an automatic transmission of a vehicle such as a tractor or a large truck in which the load of the vehicle greatly fluctuates.
[0046]
Further, the interlaced shift stage at the time of the skip shift is not limited to the target shift stage + 1 stage as in the present embodiment, and can be appropriately changed according to the characteristics of the engine and the transmission. Further, in the target gear position setting means 3 described above, the accelerator opening information VA is taken in as engine load information. However, the engine load information is not limited to the accelerator opening information VA. It may be information. Moreover, although the said embodiment demonstrated the case where the diesel engine was used as an engine, of course, it is also possible to apply to a gasoline engine. Furthermore, an auxiliary brake signal such as an exhaust brake, a foot brake signal, and the like may be taken in, and the intention of the driver may be estimated in consideration of such information.
[0047]
The shift control device for an automatic transmission according to the present invention is not applied only to an automatic transmission that performs shift control using the fuzzy theory as described above, but using parameters such as vehicle speed and accelerator opening. The present invention may be applied to a general automatic transmission that performs shift control. In this case, vehicle load degree α_VLThreshold values are set for parameters such as accelerator opening VA, accelerator opening change rate ΔVA, etc., and each parameter is compared with each threshold to instruct upshifts of multiple stages, or to instruct the maintenance of the current shift stage The same advantages as described above can be obtained.
[0048]
【The invention's effect】
As described above in detail, according to the shift control device for an automatic transmission according to the first aspect of the present invention, the vehicle load degree calculation means when the first shift up is set by the target shift speed setting means.The difference between the acceleration when the vehicle is accelerating on a straight flat road and the actual acceleration when the vehicle is actually accelerated isCalculated,thisIf the vehicle load degree is substantially zero and the accelerator opening detected by the accelerator opening detecting means is large, the gear stage control means gives priority to the output from the target gear setting means by the gear stage correction means. Since a multiple-stage upshift is instructed, a situation in which upshifts are continuously executed a plurality of times in a short time is avoided, and the number of shifts is reduced and the drivability is improved as compared with the prior art. In addition to the advantages, skip shift and step shift can be automatically switched according to the vehicle load conditions, etc., so there is also an advantage that a changeover switch for switching between step shift and skip shift can be eliminated. .
[0049]
In the shift control apparatus for an automatic transmission according to the second aspect of the present invention, when the one-stage downshift is set by the target shift stage setting means, the vehicle load degree is substantially zero and the accelerator opening is large. If the accelerator opening change rate is substantially zero, the gear position correction means outputs an instruction to hold the current gear position to the gear position control means in preference to the output of the target gear position setting means. In other words, even if the driving state of the vehicle has not yet caught up with the shift stage after the skip shift, it is estimated that the driving state corresponding to the current shift stage will be achieved in a short time thereafter, and the current shift stage is maintained. It is done. Therefore, downshifting immediately after the skip shift is prevented, and drivability after the skip shift is ensured.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a main configuration of a shift control apparatus for an automatic transmission according to an embodiment of the present invention.
FIG. 2 is a diagram showing a fuzzy rule in a shift control device for an automatic transmission according to an embodiment of the present invention.
[Explanation of symbols]
1 Optimum shift speed determination means as shift speed control means
1a Shift speed correction means
2 Vehicle load calculation means
3 Target gear position setting means
9 Accelerator opening change rate calculation means
79 Vehicle speed detection means
85 Accelerator opening detection means (Accelerator opening sensor)

Claims (2)

Vehicle speed detecting means for detecting the traveling speed of the vehicle;
Accelerator opening detecting means for detecting the accelerator opening of the vehicle;
Target speed setting means for setting a target speed based on detection information from the vehicle speed detection means and the accelerator opening detection means;
Shift speed control means for changing the shift speed of the transmission according to the output from the target shift speed setting means;
Vehicle load degree calculating means for calculating a difference between an acceleration when the vehicle is accelerated on a straight flat road in an empty state and an actual acceleration when the vehicle is actually accelerated, as a load degree of the vehicle;
When the first shift up is set by the target gear position setting means, the vehicle load degree calculated by the vehicle load degree calculation means is substantially zero, and the accelerator opening degree detected by the accelerator opening degree detection means A shift speed correction means for instructing the shift speed control means to shift up a plurality of speeds in priority to the output from the target shift speed setting means. Shift control device. An accelerator opening change rate calculating means for calculating an accelerator opening change rate from the accelerator opening detected by the accelerator opening detecting means;
When the first gear downshift is set by the target gear position setting means, if the vehicle load degree is substantially zero, the accelerator opening is large, and the accelerator opening change rate is substantially zero, the shift 2. The shift control for an automatic transmission according to claim 1, wherein the shift correction means instructs the shift speed control means to maintain the current shift speed in preference to the output from the target shift speed setting means. apparatus.

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