JPH062765A - Controller for automatic transmission - Google Patents

Abstract

PURPOSE:To improve the control precision by detecting the traveling state in advance and retreat according to the existence of the gear ratio change before and after the time necessary for speed change and carrying out prohibition operation for retreat in the advance traveling state. CONSTITUTION:When a selecting bar (b) is set to an advance traveling range, a control means (g) automatically selects an automatic transmission (a) to an advance gear stage. The control means (g) obtains an optimum speed change ratio on the basis of the outputs of a throttle opening degree sensor (e) and an output revolution sensor (d) and controls speed change. It is judged by a traveling state detecting means (j) if the gear ratio changes or not before and after the control means (g) judges that speed change is necessary, and when the gear ratio is changed, the advance traveling state is judged, and a retreat prohibition control means (k) prohibition-operates a retreat prohibiting means (h) in accordance. In this case, even if the lever (b) is set to a retreat traveling range through the maloperation, the automatic transmission (a) is held at an advance traveling gear stage. In the ordinary case, when the lever (b) is set to a retreat traveling range, the control means (9) selects the automatic transmission (9) to the retreat gear stage having a constant gear ratio automatically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission, and more particularly to a control device for preventing a shift to a reverse gear when traveling forward.

[0002]

2. Description of the Related Art Conventionally, as a control device for an automatic transmission that restricts switching to a reverse gear stage under a predetermined condition such as when traveling forward, there is also a control device disclosed in, for example, Japanese Patent Application Laid-Open No. 2-80860. It has been known.

This conventional device is an automatic transmission in which a forward gear or a reverse gear is automatically switched in response to an operating position of a select lever, and when the vehicle speed exceeds a predetermined value, the reverse gear is used. A reverse direction detecting means for detecting that the vehicle is in a backward traveling state and a backward traveling of the select lever when the backward traveling state is detected. It is configured to have a reverse traveling permission means for permitting switching to the reverse gear in response to an operation to the range, and while the vehicle is traveling backward with the vehicle speed exceeding a predetermined value, the select lever is moved backward. Even if the range is once returned to the neutral range and then switched back to the reverse running range, it is possible to switch to the reverse gear and improve the operability of the vehicle. It was the.

[0004]

However, in the conventional automatic transmission control device as described above, an inhibitor switch is used as the reverse detection means, and the vehicle travels backward based only on the range position detected by the inhibitor switch. Since the actual driving state is not detected, for example, there is a failure such as an excessive road surface input to the inhibitor switch and the position of the contact for detecting the range position is displaced. If a signal indicating that the inhibitor switch is in the reverse travel range is output even when the reverse drive is not being performed, such as when the reverse drive range is selected for a moment due to a malfunction or an incorrect operation, a predetermined speed is set. Even if the vehicle is traveling at a higher speed than the There was a case.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to reliably detect forward traveling and backward traveling to improve the control system.

[0006]

SUMMARY OF THE INVENTION In the present invention, the forward running and the backward running are detected based on the presence / absence of a gear ratio change before and after a shift-required timing, thereby achieving the above object.

That is, in the control device for an automatic transmission of the present invention, as shown in the claim correspondence diagram of FIG. 1, it is a gear stage for moving the vehicle forward and has a plurality of different gear ratios. In order to select a forward gear stage and an automatic transmission a capable of changing over to a reverse gear stage which is a gear stage for traveling the vehicle backwards and has a constant gear ratio, at least a forward traveling range and a reverse traveling range are selected. A select lever b to be operated, an input rotation sensor c for detecting the input shaft speed of the automatic transmission a, an output rotation sensor d for detecting the output shaft speed of the automatic transmission a, and a throttle for detecting the throttle opening. Input means f having at least an opening sensor e
And in response to the operation position of the select lever b, the automatic transmission a is automatically switched between the forward gear stage and the reverse gear stage,
Also, a control means g for performing gear shift control to an optimum gear ratio based on signals from the output shaft speed and the throttle opening,
The gear ratio of the automatic transmission a is calculated from the ratio of the reverse rotation prohibiting means h for prohibiting the automatic transmission a from switching to the reverse gear and the input / output rotation speed obtained by the rotation sensors c and d. Before and after the control means g determines that the gear ratio needs to be changed, if the gear ratio has changed, it is determined that the vehicle is traveling forward, but if there is no change in the gear ratio, it is traveling backward. There is provided a traveling state detecting means j for judging, and a backward movement inhibiting control means k for inhibiting the backward movement inhibiting means h when the traveling state detecting means j decides that the vehicle is traveling forward.

The condition for the reverse prohibition control means k to prohibit the reverse prohibition means h may be a forward traveling state of a predetermined output shaft rotation speed or more.

[0009]

When the select lever b is selected and operated in the forward drive range, the control means g automatically switches the automatic transmission a to the forward gear. Further, the control means g determines the optimum value based on the throttle opening detected by the throttle opening sensor e and the output shaft rotation speed of the automatic transmission a (which is equal to the vehicle speed) detected by the output rotation sensor d. The gear ratio is obtained, and the automatic transmission a is gear-shift controlled so as to form this gear ratio.

When performing such control, before and after the control means g determines that a shift is necessary,
The automatic transmission a shifts and the gear ratio changes.

Then, the traveling state detecting means j compares whether or not the gear ratio has changed before and after the control means g determines that the gear shift is necessary as described above, and thus the gear ratio If there is a change, it is determined that the vehicle is in the forward traveling state, and in response to this, the reverse prohibition control means k prohibits the reverse prohibition means h. In this case, during forward traveling, even if the driver operates the select lever b in the backward traveling range due to an erroneous operation or the like, the automatic transmission a is held in the forward traveling gear stage.

Further, normally, when the select lever b is operated to select the reverse travel range, the control means g automatically switches the automatic transmission a to the reverse gear. This reverse gear has a constant gear ratio.

On the other hand, the control means g, based on the throttle opening and the output shaft rotation speed, even when the vehicle is traveling backward,
Gear change control is performed to form an optimum gear ratio.
Then, when the control means g determines that the gear shift is necessary, the traveling state detection means j determines whether or not the gear ratio has changed before and after that. Since it is a gear ratio, gear shifting is not actually performed,
Since there is no change in the gear ratio before and after the control means g determines that gear shifting is necessary, it is determined that the vehicle is traveling backward. Therefore, the reverse prohibition control unit k does not cause the reverse prohibition unit h to perform the reverse prohibition operation, and the automatic transmission a can achieve the reverse gear stage.

In the apparatus according to the second aspect, the condition for the reverse prohibition control means k to prohibit the reverse prohibition means h is:
Not only is the traveling state detecting means j determined to be in the forward traveling state, but also the output shaft rotation speed is equal to or higher than a predetermined value, which may cause sudden braking or damage to the automatic transmission. It is impossible to achieve the reverse gear only when traveling forward at high speed.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

First, the configuration of the embodiment will be described.

FIG. 2 is a schematic diagram showing a control device for an automatic transmission according to a first embodiment of the present invention, in which AT is an automatic transmission, E is an engine, and the output rotation of the engine E is in the automatic transmission AT. A gear train GT that is input via the torque converter TC is incorporated.

FIG. 3 is a schematic diagram showing the structure of the gear train GT. The gear train GT includes a front planetary gear set 2 including a front sun gear 2s, a front pinion gear 2p, a front internal gear 2i, and a front carrier 2c. Rear sun gear 4s, rear pinion gear 4p, rear internal gear 4i, rear carrier 4c
And a rear planetary gear set 4 having the above are arranged in tandem. An output shaft (output shaft) OUT is coupled to the rear carrier 4c.

The gear train GT has a reverse clutch R / C connecting the input shaft (input shaft) IN and the front sun gear 2s, a high clutch H / C connecting the input shaft IN and the front carrier 2c, and a front clutch. A forward clutch F / C connecting the carrier 2c and the rear internal gear 4i, a band brake B / B fixing the front sun gear 2s to the housing side, a low-and-reverse brake L & R / B fixing the front carrier 2c to the housing side, etc. Friction elements are provided.

Further, a forward one-way clutch F / O.C is provided between the forward clutch F / C and the rear internal gear 4i, and a low one-way clutch L / is provided between the front carrier 2c and the housing. An O / C is provided, and an overrun clutch O / R / C is arranged in parallel with the forward one-way clutch F / O / C between the front carrier 2c and the rear internal gear 4i.

By the way, in the power train, as shown in Table 1 below, various friction elements are line pressures as hydraulic fluid pressures supplied from a hydraulic pressure supply circuit CV installed above the automatic transmission AT. By engaging and disengaging with each other, it is possible to obtain various reverse speeds (reverse gear speeds) and various shift speeds of the first to fourth forward gear speeds.

[0022]

[Table 1] In addition, in this table, a circle indicates a fastening state, and a blank indicates an open state.

The forward one-way clutch F / O.C is free when the rear internal gear 4i is rotated in the forward rotation direction with respect to the front carrier 2c, is locked when it is rotated in the reverse rotation direction, and is the low one-way clutch. L / O / C is free when the front carrier 2c rotates in the forward direction, and locked when rotating in the reverse direction.

By the way, the overrun clutch OR
/ C is not shown in Table 1, but by engaging this overrun clutch O / R / C, the function of the forward one-way clutch F / O / C is lost and the engine brake is operated. Has become.

As described above, the line pressure for operating the friction element and the supply / stop of the line pressure are performed by the operation of the hydraulic pressure supply circuit (control means) CV based on the select operation of the select lever SL. Further, a part of the valve (not shown) in the hydraulic pressure supply circuit CV is shown in FIG.
It is controlled by the A / T control unit (control means) 10 and the solenoids 11 to 15 shown in FIG. That is, the A / T control unit 10 has an inhibitor switch 21 including a 1-range switch, a 2-range switch, a D-range switch, a P-range switch, and an R-range switch as input means, a vehicle speed sensor 22, and an oil temperature sensor 23. , An ECC control unit 30 having an input rotation sensor 24 for detecting the rotation speed of the input shaft IN and controlling the drive of the engine E.
Idle switch 31, full throttle switch 32, throttle sensor (throttle opening sensor) 3 via
3, the signal from the engine speed sensor 34 is input. The drive of the line pressure solenoid 11, the lockup solenoid 12, the first shift solenoid 13, the second shift solenoid 14, the timing solenoid 15, and the oil passage switching solenoid 16 is controlled based on these signals.

Then, as shown in Table 2 below, each shift speed can be obtained by switching ON / OFF of the first and second shift solenoids 13 and 14.

[0027]

[Table 2] By the way, the switching of the first and second shift solenoids 13 and 14 by the A / T control unit 10 is
It is determined based on the throttle opening obtained from the throttle sensor 33 and the vehicle speed signal obtained from the vehicle speed sensor 22. For example, shift control is performed according to the shift schedule shown in FIG. 4, which is determined by the vehicle speed and the throttle opening. . With reference to this shift schedule, whether or not it is the time when a gear shift is necessary includes not only when the vehicle travels forward when the gear shift is actually performed but also when the vehicle travels backward when the gear shift is not actually performed at a constant gear ratio. It is always done.

The oil passage switching solenoid 16 of this embodiment is also used.
Is for operating the oil passage switching valve 7 as a reverse prohibiting means. That is, in this embodiment, as shown in FIG. 5, the reverse clutch R in the hydraulic pressure supply circuit CV is used.
An oil passage switching valve 7 is provided in the middle of an oil passage 71 that supplies hydraulic pressure to / C. And this oil passage switching valve 7
Is formed so as to be switchable between a first position for supplying hydraulic pressure to the reverse clutch R / C and a second position for draining the hydraulic pressure to the tank T, and the oil passage switching solenoid 16 is not normally driven. At the time, it is in the first position, but when the oil passage switching solenoid 16 is driven, it is switched to the second position. This second
When the position is switched to the position, the oil pressure in the oil passage 71 is drained, so the select lever SL is operated to the reverse range, and the manual valve (not shown) in the hydraulic pressure supply circuit CV reverse clutch R / C. Even when the hydraulic pressure is supplied to the reverse clutch R / C, the reverse speed is not achieved in the automatic transmission AT because the reverse clutch R / C is not engaged.

Next, the control operation of the A / T control unit 10 will be described.

First, the shift control will be described with reference to the flowchart of FIG.

That is, this flowchart shows the shift control routine, and step 101 is a step of reading the throttle opening TH obtained from the throttle sensor 33 and the vehicle speed V obtained from the vehicle speed sensor 22.

Step 102 is a step for referring to the shift schedule shown in FIG. 4 based on the throttle opening TH and the vehicle speed V.

In step 103, the reference result of step 102 determines whether or not a shift is necessary. If YES, the process proceeds to step 104, and if NO, the process proceeds to step 105.

Step 104 is a step in which the gear shift required flag f _{1 is set} to 1 and the shift solenoids 13 and 14 are driven according to the reference result of step 102 in correspondence with Table 2 above.

Step 105 is a step of setting the gear shift required flag f ₁ to zero. It should be noted that this gear shift required flag f
₁ is set to 0 at the time of initial setting.

Further, the A / T control unit 1
0 performs the traveling state determination control for determining whether the automatic transmission AT is in the forward traveling state in which the forward gears of the first speed to the fourth speed are set or in the reverse traveling state in which the reverse speed is set. ing.

FIG. 7 shows a judgment routine which is this running state judgment control. In step 201, the input shaft rotation speed N _IN obtained by the input rotation sensor 24 and the vehicle speed sensor 22 are shown.
This is a step of reading the output shaft rotation speed N _OUT (= V) obtained in step.

In step 202, the rotational speeds N _IN and N _{OUT are set.}
Is a step of calculating the gear ratio G of the automatic transmission AT based on

In step 203, the shift required flag f
Whether ₁ is 1 (throttle opening TH and vehicle speed V
Is a step of determining whether or not a shift is necessary in the shift schedule of FIG. 4), the process proceeds to step 204 if YES, and proceeds to step 207 if NO.

Step 204 is a step of judging whether or not the latest gear ratio G is equal to the reference gear ratio G ₀ which is the previous gear ratio. If YES, then the routine proceeds to step 205, where NO
Then, the process proceeds to step 206.

In step 205, the shift flag F _{D is set} to 0.
And the step.

In step 206, the shift flag F _{D is set} to 1
And the step.

Step 207 is a step of rewriting the reference gear ratio G ₀ with the calculation result of step 202.

As described above, the shift flag F _D is such that the gear ratio (G) before and after the throttle opening TH and the vehicle speed V become values that require the gear shift (the gear shift necessary flag f ₁ becomes 1). Is set up as a result of the comparison of G ₀ ) with G ₀ ), and the shift flag F _D = 0 indicates that the gear ratio G is in a constant backward traveling state because the gear ratio G does not change at this time. The shift flag F _D = 1 indicates the forward traveling state because the gear ratio G is changing.

Further, the A / T control unit 10
Prevents the automatic transmission AT from achieving the reverse gear stage even if the select lever is accidentally operated to the reverse traveling range during forward traveling, and sudden braking, engine stall, or automatic transmission AT is prevented.
The reverse prohibition control is performed to prevent damage to the vehicle.

FIG. 8 shows a prohibition control routine which is the reverse prohibition control, and step 301 is a step of judging whether or not the vehicle speed V is equal to or higher than a predetermined vehicle speed V ₀ , and YES.
Then, the process proceeds to step 303, and if NO, the process proceeds to step 302.

Step 302 is a step of setting the running state flag F _D to zero.

Step 303 is a step for determining whether or not the traveling state flag F _D is 1, and if YES, the process proceeds to step 304, and if NO, the process proceeds to step 305.

Step 304 is the oil passage switching solenoid 1
6 is a step of driving 6.

Step 305 is an oil passage switching solenoid 1
6 is a step of stopping driving.

A) When traveling forward above a predetermined vehicle speed V ₀ When the select lever SL is selectively operated to a forward traveling range such as the D range, the A / T control unit 10 sets the vehicle speed V and the throttle opening TH. It is determined by referring to the shift schedule shown in FIG.
3) If necessary, the automatic transmission AT is automatically switched to the first speed to the fourth speed (step 104).

By the way, in this way, the automatic transmission AT
When shifting from 1st to 4th forward speed,
T control unit 10 is each shift solenoid 1
The gear ratio G changes before and after driving the gears 3, 14.

Therefore, every time the A / T control unit 10 determines that a gear shift is necessary in the gear shift control routine, the gear shift necessary flag f ₁ is set to 1 (step 104). Reference gear ratio G, which is the gear ratio one time before when the gear shift required flag f _{1 is set} to 1.
₀ and the gear ratio G after the gear shift required flag f _{1 is set} to 1 do not match, and the traveling state flag F _{D is set} to 1 to determine the forward drive state.

Therefore, when the vehicle speed V is equal to or higher than the predetermined vehicle speed V ₀ ,
Drive the oil passage switching solenoid 16 (step 301
(→ 303 → 304), even if the select lever SL is switched to the R range due to an erroneous operation, the reverse clutch R /
C is not engaged, the automatic transmission AT does not reach the reverse speed, and sudden braking or engine stall does not occur or the automatic transmission AT is damaged.

[0055] b) during forward travel of less than a predetermined vehicle speed V _0, when the vehicle is stopped, or in a forward running state or stopped state of less than the time backward traveling a predetermined vehicle speed V _0,
When the select lever SL is selectively operated to the R range, a manual valve (not shown) is activated to supply hydraulic pressure from the oil passage 71 to the reverse clutch R / C, and in parallel with that, the low and reverse brake L & R / B. Is also supplied with hydraulic pressure, and both R / C and L & R / B are engaged,
The automatic transmission AT is automatically switched to the reverse gear.

That is, in the forward traveling state or the stopped state where the vehicle speed is lower than the predetermined vehicle speed V ₀ , the drive of the oil passage switching solenoid 16 is stopped (steps 301 → 302 → 30).
5) Since the hydraulic pressure can be supplied to the oil passage 71, the above operation can be achieved.

Further, when the select lever SL is selectively operated to the R range while the vehicle is traveling in reverse (for example, this is the R range, once in the backward traveling, the range is set to the N range and then to the R range again). In this case, the A / T control unit 10 performs control by the shift control routine shown in FIG. 6 even when the vehicle travels backward with a constant gear ratio. Therefore,
When the throttle opening TH and the vehicle speed V have a relationship that requires a shift in the shift schedule of FIG. 4, the shift required flag f ₁ is set to 1 and each shift solenoid 1
3 and 14 are also switched and driven. In this case, even if the shift solenoids 13.14 are driven, the hydraulic pressure is not supplied from the valves operated by these solenoids to the friction elements such as the clutches and brakes. When the gear shift required flag f ₁ is set to 1 in this way,
In the determination routine of, the gear ratios G ₀ and G before and after the setting are compared, and in this case, since the reverse speed is a constant gear ratio, they both match and the traveling state flag F _D indicates that the vehicle is traveling backward. It is set to 0 as shown.

Therefore, in the reverse prohibiting routine shown in FIG. 8, the flow is from step 301 to 303 to 305.
The oil passage switching solenoid 16 is not driven, and in the oil passage 71,
The hydraulic pressure can be supplied to the reverse clutch R / C.
Therefore, when the select lever SL is set to the R range as described above, the automatic transmission AT becomes reverse speed.

As described above, in the first embodiment, it is determined whether the vehicle is in the forward traveling state or the backward traveling state depending on whether or not the gear ratio of the automatic transmission AT is changed, and only when the vehicle is traveling forward at the predetermined vehicle speed V ₀ or higher, Since the automatic transmission AT is prohibited from moving in reverse speed, the inhibitor switch
Compared to determining forward / reverse traveling at the position of the select lever SL as shown in 1, it is possible to accurately determine the actual forward / reverse traveling state, prevent erroneous detection, and perform highly accurate control. The effect of enabling is obtained. Further, similarly to the conventional case, the reverse speed is effective in preventing sudden braking, engine stall, and damage to the automatic transmission. Even when the vehicle speed is equal to or higher than the predetermined vehicle speed V ₀ , the reverse speed is achieved in the reverse traveling state. Naturally, it is possible to obtain the effect of improving usability.

In addition, the inhibitor switch 21 is composed of contacts which are always provided in the movable parts, and there is a risk of occurrence of a failure such as displacement of the contacts due to excessive road surface input. The input rotation sensor 24 and the vehicle speed sensor 22 used in the example are fixed to the case of the automatic transmission AT, and are unlikely to fail.

Next, a second embodiment of the present invention will be described. In describing the second embodiment, the description of the same configuration and operation as those of the first embodiment will be omitted.
Only the differences from the embodiment will be described.

This second embodiment is an improvement of the prior art, and this improvement is based on the AT control unit 1
The prohibition control routine of 0 will be described with reference to FIG.

In step 401, the vehicle speed V is the predetermined vehicle speed V _0.
In the step of determining whether or not it is the above, YES is taken to step 402, and NO is taken to step 404.

Step 402 is a step for determining whether or not the select flag FS is 1, and if YES, then the process proceeds to step 406, and if NO, the process proceeds to step 403.

Step 403 is the oil passage switching solenoid 1
6 is a step of driving 6 to prohibit the automatic transmission AT from moving backward.

Step 404 is the inhibitor switch 2
1 is a step of determining whether or not the R range is detected. If YES, the process proceeds to step 406, and if NO, step 4
Go to 05.

Step 405 is a step of setting the select flag FS to 0, and step 406 is a step of setting the select flag FS to 1. That is, when the select flag FS is 0, the inhibitor switch 21 detects the R range, and when it is 1, it indicates that the range excluding the R range is detected.

In step 407, it is determined whether or not the traveling state flag F _D described in the first embodiment is 1, that is, it is determined that the vehicle is in the forward traveling state. If YES, the process proceeds to step 403. , NO, the process proceeds to step 408.

In step 408, the oil passage switching solenoid 1
Step 6 is a step in which the automatic transmission AT is allowed to reach the reverse speed by setting the driving stop state.

Therefore, in the second embodiment, in the prior art, the vehicle speed V is equal to or higher than the predetermined vehicle speed V ₀ ,
In the middle of the flow from step 401 → 402 → 406 to step 408, which is a flow that allows the vehicle to reach the reverse speed even if the vehicle is in the reverse state again, in step 407 before step 408, the actual traveling state is set. The judgment based on it is added.

As a result, although the inhibitor switch 21 breaks down or the like, although the vehicle speed V is actually in the forward traveling state at or above the predetermined vehicle speed V ₀ , in the conventional case, the vehicle is allowed to move backward. Also, a high fail-safe function is obtained by prohibiting the formation of the reverse speed.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and even if there are design changes within the scope not departing from the gist of the present invention. Included in the present invention.

For example, in the second embodiment, when the judgment by the inhibitor switch and the actual traveling state are different, it may be displayed.

[0074]

As described above, in the control device for an automatic transmission according to the present invention, it is determined whether the vehicle is traveling forward or traveling backward depending on whether or not there is a gear ratio change before and after a gear shift required time. The running state detecting means and the reverse prohibition control means for prohibiting the reverse prohibiting means when the running state detecting means determines that the vehicle is in the forward running state are provided. It is possible to accurately determine whether the vehicle is in the forward traveling state or the backward traveling state as compared with the case where the forward / backward traveling is determined by the position of the select lever, which prevents erroneous detection and enables highly accurate control. The effect is obtained.

Further, in the apparatus according to the second aspect, not only the traveling state detecting means determines that the vehicle is in the forward traveling state, but also the fact that the output shaft rotation speed is equal to or higher than the predetermined value inhibits the reverse movement inhibiting control means. As a condition to be set, the reverse gear can not be achieved only when traveling forward at a high speed to a certain extent where there is a risk of sudden braking or damage to the automatic transmission, so that usability is improved.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a control device for an automatic transmission according to the present invention.

FIG. 2 is an overall system diagram showing a first embodiment device of the present invention.

FIG. 3 is a structural explanatory view showing a gear train of the first embodiment device.

FIG. 4 is a characteristic diagram showing a shift schedule of the device of the first embodiment.

FIG. 5 is a circuit diagram showing a main part of the first embodiment device.

FIG. 6 is a flowchart showing a shift control routine of the first embodiment device.

FIG. 7 is a flowchart showing a determination routine of the first embodiment device.

FIG. 8 is a flowchart showing a prohibition control routine of the first embodiment device.

FIG. 9 is a flowchart showing a prohibition control routine of the second embodiment device.

[Explanation of symbols]

 a automatic transmission b select lever c input rotation sensor d output rotation sensor e throttle opening sensor f input means g control means h reverse prohibition means j running condition detection means k reverse prohibition control means

Claims (2)

[Claims] 1. A forward gear having a plurality of different gear ratios for causing a vehicle to travel forward, and
An automatic transmission that is capable of switching to a reverse gear that has a constant gear ratio and that is a gear to drive the vehicle in reverse, and a select lever that is operated to select at least a forward drive range and a reverse drive range, Input means having at least an input rotation sensor for detecting an input shaft rotation speed of the automatic transmission, an output rotation sensor for detecting an output shaft rotation speed of the automatic transmission, and a throttle opening sensor for detecting a throttle opening, In response to the operation position of the select lever, the automatic transmission is automatically switched between the forward gear and reverse gear, and the gear ratio is controlled to the optimum gear ratio based on the signals from the output shaft speed and the throttle opening. The control means for performing the operation, the reverse prohibiting means for prohibiting the automatic transmission from switching to the reverse gear, and the automatic transmission are controlled by the ratio of the input and output speeds obtained by the respective rotation sensors. Before and after the gear ratio in the transmission is determined and the control unit determines that the gear ratio needs to be changed, if the gear ratio has changed, it is determined that the vehicle is traveling forward, while the gear ratio changes. If the vehicle is traveling backward, it is determined that the vehicle is traveling backward, and when the traveling state detecting means determines that the vehicle is traveling forward, the vehicle is provided with reverse prohibition control means for prohibiting the reverse prohibiting means. A control device for an automatic transmission, characterized in that 2. The control device for an automatic transmission according to claim 1, wherein the condition for the reverse prohibition control means to prohibit the reverse prohibition means is a forward traveling state at a predetermined output shaft speed or more.