JP5480209B2 - Automatic transmission for vehicles - Google Patents

Description

  The present invention relates to an automatic transmission for a vehicle in which a reverse driven gear that is rotated by a drag torque of a hydraulic clutch is coupled to an output shaft by meshing engagement means to establish a reverse gear.

  Disengage the clutch placed between the engine and the gearbox to prevent gear ringing by establishing the reverse gear with the speed of each gear in the gearbox decreasing over time. An automatic transmission that performs such a process is known from Japanese Patent Application Laid-Open No. H10-228707.

  Further, the automatic transmission prohibits shifting to the reverse gear stage when the forward vehicle speed exceeds a predetermined value and the rotational speed of each gear increases, and the throttle opening is large and the shift is performed. When the position is the neutral position, the clutch is disengaged to reduce the rotational speed of each gear.

JP-A-54-79352

By the way, in an automatic transmission that establishes a reverse gear by connecting a reverse driven gear that is rotatably supported on an output shaft to an output shaft by meshing engagement means such as a dog clutch, a hydraulic pressure is provided between the engine and the reverse driven gear. When the clutch is arranged, by its hydraulic clutch also be disengaged, will rotate the reverse driven gear in drag torque, the differential rotation between the rotating stopped meshing engagement means for generating There is a possibility that the smooth operation of the meshing engagement means is hindered.

  In order to prevent this, when the engine speed is equal to or less than a predetermined value, that is, when the rotation of the reverse driven gear is equal to or lower than the predetermined value, the meshing engagement means that has stopped rotating is permitted. In addition, the differential rotation of the reverse driven gear can be kept low, and the meshing engagement means can be smoothly operated.

  However, the driver does not always shift-change to the reverse shift stage when the vehicle is completely stopped, and may change to the reverse shift stage while the vehicle is traveling forward at a low speed. In this case, the rotation of the drive wheel is reversely transmitted to the meshing engagement means provided on the output shaft, and the differential rotation with the reverse driven gear that rotates with the drag torque of the hydraulic clutch increases, so the engine speed is less than a predetermined value. Even if it exists, there exists a possibility that a meshing engagement means cannot operate | move smoothly.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to prevent the meshing engagement means from operating at an inappropriate timing even when the rotational speed of the drive source or the vehicle speed changes.

To achieve the above object, according to the first aspect of the present invention, an input shaft to which a driving force from a driving source is input, an output shaft that outputs the driving force to driving wheels, the input shaft, A plurality of gears provided on the output shaft and meshing with each other; a hydraulic clutch that establishes a predetermined forward shift stage by coupling any of the plurality of gears to the input shaft; and provided on the input shaft. wherein a reverse drive gear capable of binding to said input shaft by a hydraulic clutch, a reverse driven gear can be coupled to more output shaft to be in meshing engagement Gote stage provided on the output shaft, the reverse drive gear and the reverse driven gear operation of the reverse idle gear and the hydraulic clutch and the meshing engagement means in accordance with a running state of the shift position and the vehicle selected by the shift lever to connect the Shift control means for performing a shift by controlling, and the shift control means engages the hydraulic clutch in a state where the reverse driven gear is coupled to the output shaft by the meshing engagement means to change the reverse shift stage. the vehicle automatic transmission that establishes the gear shift control unit, the calculates the differential rotation of the reverse driven gear and the meshing engagement means, the differential rotation is less than the predetermined value and the selected shift position is The meshing engagement means is actuated when in the reverse position, and after the start of the operation, the meshing engagement means is selected if the selected shift position is the reverse position even if the differential rotation exceeds a predetermined value. Even if the selected shift position becomes the parking position, the differential rotation is the predetermined value. The vehicle automatic transmission according to claim Rukoto to continue the operation of the meshing engagement means is proposed if fully.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, the input shaft rotational speed detecting means for detecting the input shaft rotational speed and the output shaft rotational speed detecting means for detecting the output shaft rotational speed. And the shift control means calculates the differential rotation based on the input shaft rotation speed and the output shaft rotation speed.

  The first input shaft 13 of the embodiment corresponds to the input shaft of the present invention, the 4-speed-reverse clutch C4 of the embodiment corresponds to the hydraulic clutch of the present invention, and the engine E of the embodiment corresponds to the present invention. The electronic control unit U of the embodiment corresponds to the shift control means of the present invention.

  According to the configuration of claim 1, in the state where the selector has disconnected the reverse driven gear from the output shaft, the rotation of the input shaft connected to the drive source is transmitted to the reverse drive gear by the drag torque of the hydraulic clutch that is disengaged, The rotation of the reverse drive gear is transmitted to the reverse driven gear via the reverse idle gear. On the other hand, since the rotation of the drive wheel is transmitted to the output shaft to rotate the meshing engagement means, a differential rotation occurs in the reverse driven gear and the meshing engagement means, and this differential rotation increases as the rotational speed of the drive source increases. Also, the larger the vehicle speed, the larger it becomes.

When the reverse driven gear and the meshing engagement means are in a large differential rotation, if the meshing engagement means is engaged with the reverse driven gear in order to establish the reverse gear, the engagement is not smoothly performed due to the differential rotation and noise is generated. May generate vibrations or adversely affect the durability of the meshing engagement means, but the meshing engagement means is only activated when the differential rotation is less than the predetermined value, and the differential rotation is greater than the predetermined value. it is possible to solve the above problem by prohibiting the operation of Waso at.

Further, the shift control means continues the operation of the meshing engagement means if the shift position is the reverse position even after the differential rotation becomes equal to or greater than the predetermined value after the operation of the meshing engagement means is started. Even if the position becomes the parking position, if the differential rotation is less than the predetermined value, the operation of the meshing engagement means is continued, so that the intermediate engagement of the meshing engagement means can be prevented.

According to the second aspect of the present invention, the input shaft rotational speed has a fixed relationship with the rotational speed of the reverse driven gear, and the output shaft rotational speed has a fixed relationship with the rotational speed of the meshing engagement means. The differential rotation of the reverse driven gear and the meshing engagement means can be calculated from the rotation speed and the output shaft rotation speed. In addition, since the existing input shaft rotation speed detection means and output shaft rotation speed detection means can be used, it is not necessary to provide special rotation speed detection means for detecting the rotation speed of the reverse driven gear and the rotation speed of the meshing engagement means.

Skeleton diagram of parallel shaft type automatic transmission. 2 is an enlarged view of part 2 of FIG. The block diagram of the control system of an automatic transmission. Explanatory drawing of the method of calculating differential rotation from input shaft rotation speed and output shaft rotation speed. The graph which shows the conditions of the vehicle speed, differential rotation, and engine speed which prohibit the action | operation of a selector. The flowchart explaining an effect | action.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 shows a parallel shaft type automatic transmission T having five forward speeds and one reverse speed. (A) shows the entire automatic transmission T, and (B) shows only a part hidden behind (A).

  A first input shaft 13 is coaxially connected to the crankshaft 11 of the engine E via a torque converter 12. A second input shaft 14, an output shaft 15, an idle shaft 16 and a reverse shaft are connected to the first input shaft 13. An idle shaft 17 is arranged in parallel. A drive gear 18 fixed to the first input shaft 13 meshes with a first idle gear 19 fixed to the idle shaft 16, and a second idle gear 20 fixed to the idle shaft 16 is fixed to the second input shaft 14. Meshed with the driven gear 21. Thus, the first input shaft 13 and the second input shaft 14 are always connected and rotate in the same direction at a predetermined ratio.

  A first speed drive gear 22, a second speed drive gear 23, and a third speed drive gear 24 are supported on the second input shaft 14 so as to be relatively rotatable. The first speed drive gear 22 receives a second input via a first speed clutch C1. The second speed drive gear 23 can be coupled to the second input shaft 14 via the second speed clutch C2, and the third speed drive gear 24 can be coupled to the second input shaft 14 via the third speed clutch C3. Can be combined. A 4-speed drive gear 25, a 5-speed drive gear 26 and a reverse drive gear 27 are supported on the first input shaft 13 so as to be relatively rotatable. The 4-speed drive gear 25 is connected to the first input via a 4-speed-reverse clutch C4. The 5-speed drive gear 26 can be connected to the first input shaft 13 via the 5-speed clutch C5, and the reverse drive gear 27 connected integrally with the 4-speed drive gear 25 is 4 It can be coupled to the first input shaft 13 via the speed-reverse clutch C4.

  A first speed driven gear 28, a second speed driven gear 29, a third speed driven gear 30 and a fifth speed driven gear 32 are fixed to the output shaft 15, and a fourth speed driven gear 31 and a reverse driven gear 33 are supported so as to be relatively rotatable. The first speed driven gear 28, the second speed driven gear 29, the third speed driven gear 30, the fourth speed driven gear 31 and the fifth speed driven gear 32 are respectively a first speed drive gear 22, a second speed drive gear 23, a third speed drive gear 24, and a fourth speed drive gear 25. The reverse driven gear 33 is connected to the reverse drive gear 27 via a reverse idle gear 34 that is rotatably supported on the reverse idle shaft 17. The 4-speed driven gear 31 and the reverse driven gear 33 can be selectively coupled to the output shaft 15 via a selector S formed of a dog clutch.

Meshes with a final driven gear 36 of final drive gear 35 fixedly provided on the output shaft 15 is fixed to the casing of the differential gear D F, the driving wheels W of the drive shaft 37 is horizontally extending in the lateral from the differential gear D F, W Connected to.

  As shown in FIG. 3, the electronic control unit U that controls the shift of the automatic transmission T has an input shaft rotational speed detection means Sa that detects the rotational speed of the first input shaft, and detects the rotational speed of the output shaft. Output shaft rotational speed detecting means Sb, shift position detecting means Sc for detecting the shift position designated by the shift lever, vehicle speed detecting means Sd for detecting the vehicle speed from the rotational speed of the final driven gear 36, for example, and detecting the engine rotational speed The engine speed detecting means Se for performing the operation and the accelerator opening detecting means Sf for detecting the accelerator opening are connected.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  Based on the shift position detected by the shift position detecting means Sc, the vehicle speed detected by the vehicle speed detecting means Sd, and the accelerator opening detected by the accelerator opening detecting means Sf, the electronic control unit U is connected to the first speed clutch C1, A predetermined gear position is established in the automatic transmission T by controlling the operations of the second speed clutch C2, the third speed clutch C3, the fourth speed-reverse clutch C4, the fifth speed clutch C5 and the selector S.

That is, when the drive position D is selected by the shift lever, when the first speed clutch C1 is engaged, the driving force of the engine E is changed from the first input shaft 13 → the drive gear 18 → the first idle gear 19 → the idle shaft 16 → Second idle gear 20 → driven gear 21 → second input shaft 14 → first speed clutch C1 → first speed drive gear 22 → first speed driven gear 28 → output shaft 15 → final drive gear 35 → final driven gear 36 → differential gear DF → drive It is transmitted to the left and right drive wheels W, W through the path of the shafts 37, 37 to establish the first gear.

When the second speed clutch C2 is engaged, the driving force of the engine E is changed from the first input shaft 13 to the drive gear 18 to the first idle gear 19 to the idle shaft 16 to the second idle gear 20 to the driven gear 21 to the second input shaft 14 to the second input shaft 14. the second clutch C2 → second speed drive gear 23 → second speed driven gear 29 → output shaft 15 → final drive gear 35 → final driven gear 36 → differential gear D F → driven wheels W of the left and right in the path of the drive shaft 37, the W The second gear is established.

When the third speed clutch C3 is engaged, the driving force of the engine E is changed from the first input shaft 13 → drive gear 18 → first idle gear 19 → idle shaft 16 → second idle gear 20 → driven gear 21 → second input shaft 14 → 3rd speed clutch C3 → 3rd speed drive gear 24 → 3rd speed driven gear 30 → Output shaft 15 → Final drive gear 35 → Final driven gear 36 → Differential gear DF → Drive shafts 37, 37 are connected to the left and right drive wheels W, W Then, the third gear is established.

When the selector S, which is a dog clutch, is moved to the right and the 4-speed-reverse clutch C4 is engaged with the 4-speed driven gear 31 coupled to the output shaft 15, the driving force of the engine E is changed from the first input shaft 13 to the 4-speed-river. Scratch C4 → 4-speed drive gear 25 → 4-speed driven gear 31 → selector S → output shaft 15 → final drive gear 35 → final driven gear 36 → differential gear DF → right and left drive wheels W, W along the drive shafts 37, 37 And the fourth gear is established.

When the fifth speed clutch C5 is engaged, the driving force of the engine E is changed from the first input shaft 13 → the fifth speed clutch C5 → the fifth speed drive gear 26 → the fifth speed driven gear 32 → the output shaft 15 → the final drive gear 35 → the final driven gear 36 → The differential gear D F is transmitted to the left and right drive wheels W, W through the path of the drive shafts 37, 37, and the fifth gear is established.

When the reverse position R is selected with the shift lever, the selector S is first moved to the left to couple the reverse driven gear 33 to the output shaft 15 and then the 4-speed-reverse clutch C4 is engaged. As a result, the driving force of the engine E is changed from the first input shaft 13 to the 4th speed-reverse clutch C4 → the reverse drive gear 27 → the reverse idle gear 34 → the reverse driven gear 33 → the selector S → the output shaft 15 → the final drive gear 35 → the final driven gear. 36 → Differential gear DF → Drive shafts 37, 37 are transmitted in reverse to the left and right drive wheels W, W, and the reverse gear is established.

  By the way, when the selector S is moved to the left to establish the reverse gear and the reverse driven gear 33 is coupled to the output shaft 15, the reverse driven gear 33 that is rotatably supported by the output shaft 15 and the output shaft 15 are fixed. The differential rotation with the selected selector S prevents smooth engagement between the dog teeth of the selector S and the dog teeth of the reverse driven gear 33, which may cause noise and vibration or adversely affect the durability of the selector S. There is sex.

The reason why differential rotation occurs between the reverse driven gear 33 and the selector S is as follows. When the vehicle is stopped, the output shaft 15 and the selector S are connected to the left and right drive wheels W, W via the final drive gear 35, the final driven gear 36, the differential gear DF, and the drive shafts 37, 37 for rotation. It is in a stopped state. On the other hand, even when the 4-speed-reverse clutch C4 is disengaged, the drag torque causes rotation of the crankshaft 11 of the engine E from the first input shaft 13 via the 4-speed-reverse clutch C4. 27 and transmitted from the reverse drive gear 27 to the reverse idle gear 34 and the reverse driven gear 33, a differential rotation occurs between the stopped selector S and the reverse driven gear 33 rotating in the direction of arrow A in FIG. It will be.

In principle, the vehicle is stopped when the reverse gear is established, but when the driver shifts from the forward gear to the reverse gear, the vehicle moves forward at a slow speed without completely stopping. There is a case. Thus, when the vehicle is moving forward at a slow speed, the rotation of the drive wheels W, W is transmitted back to the output shaft 15 via the drive shafts 37, 37, the differential gear D F , the final driven gear 36, and the final drive gear 35. The output shaft 15 and the selector S are rotated in the direction of arrow B opposite to the direction of arrow A, which is the direction of rotation of the reverse driven gear 33. As described above, when the vehicle is traveling forward, the differential rotation between the selector S and the reverse driven gear 33 becomes larger than when the vehicle is stopped, and there is a problem that smooth engagement of the dog teeth of the selector S becomes more difficult.

  Therefore, in the present embodiment, when the differential rotation between the reverse driven gear 33 and the selector S is a predetermined value (for example, 1000 rpm) or more, the left movement of the selector S is prohibited, and the dog teeth of the selector S and the dog teeth of the reverse driven gear 33 are excluded. Are not smoothly engaged with each other, and noise and vibration are prevented, and the durability of the selector S is prevented from being lowered.

  As shown in FIG. 4, the differential rotation between the reverse driven gear 33 and the selector S is the input shaft rotational speed (the rotational speed of the first input shaft 13) detected by the existing input shaft rotational speed detection means Sa in the automatic transmission. It is calculated based on the output shaft rotational speed (the rotational speed of the output shaft 15) detected by the output shaft rotational speed detection means Sb. That is, since the friction of the reverse drive gear 27, the reverse idle gear 34, and the reverse driven gear 33 is smaller than the drag torque of the 4-speed-reverse clutch C4, there is almost no slip in the transmission path from the first input shaft 13 to the reverse driven gear 33. Therefore, the rotational speed of the reverse driven gear 33 is divided by dividing the input shaft rotational speed by the ratio from the first input shaft 13 to the reverse driven gear 33, that is, the ratio of the reverse drive gear 27, the reverse idle gear 34, and the reverse driven gear 33. Can be calculated.

  Further, since the output shaft rotational speed detecting means Sb has a minimum detectable rotational speed, the higher one of the detected rotational speed of the output shaft rotational speed detecting means Sb and the minimum rotational speed is selected. Select the output shaft speed. Then, the rotation speed of the selector S is calculated by multiplying the selected rotation speed of the output shaft by the ratio from the output shaft 15 to the selector S (1 in the embodiment), and the rotation speed of the reverse driven gear 33 that is opposite to each other. Further, by adding the rotation speed of the selector S, the differential rotation can be calculated.

  As described above, since the existing input shaft rotation speed detection means Sa and output shaft rotation speed detection means Sb used for calculating the differential rotation can be used as they are, the rotation speeds of the reverse driven gear 33 and the selector S are detected. There is no need to provide a special detection means.

  As shown in FIG. 5, the differential rotation for prohibiting the left movement of the selector S is 1000 rpm. When the vehicle speed is zero and the rotation speed of the selector S is zero, there is a predetermined ratio between the crankshaft 11 and the reverse driven gear 33, so the engine rotation speed at which the differential rotation is 1000 rpm is 2000 rpm. That is, when the vehicle speed is zero, the differential rotation is 1000 rpm when the engine speed is 2000 rpm. When the forward vehicle speed increases, the rotational speed of the selector S connected to the drive wheels W and W increases. Therefore, in order to suppress the differential rotation to less than 1000 rpm, the engine rotational speed needs to be lower than 2000 rpm when the vehicle speed is zero. There is. For example, when the vehicle speed is 8 km / h, the engine speed needs to be lower than 1200 rpm.

  The first idle speed of the engine E changes in the range of 1200 rpm to 1700 rpm depending on the coolant temperature, but if the vehicle speed is zero, the differential speed exceeds the upper limit of 1000 rpm within the range of the first idle speed. There is no.

  Next, the above operation will be further described based on the flowchart of FIG.

  First, in step S1, the rotation speed of the reverse driven gear 33 is calculated, and in step S2, the rotation speed of the output shaft 15 detected by the output shaft rotation speed detection means Sb and the minimum rotation speed that can be detected by the output shaft rotation speed detection means Sb are obtained. The number of rotations of the selector S is calculated from the number of rotations of the output shaft 15 that has been high-selected in comparison and high-selected in step S3, and the differential rotation of the reverse driven gear 33 and the selector S is calculated in step S4.

When the shift position detected by the shift position detection means Sc in step S5 is the reverse position R , the vehicle speed detected by the vehicle speed detection means Sd in step S6 is less than a predetermined value (for example, see 8 km / h in FIG. 5). Ri, and the engine speed is a predetermined value detected by the engine speed detecting means Se in step S7 (e.g., 2000 rpm see FIG. 5) Ri less der, and the differential rotation of the reverse driven gear 33 and the selector S in step S8 is predetermined If it is less than the value (for example, see 1000 rpm in FIG. 5), the in-gear of the reverse gear, that is, the left movement of the selector S is permitted in step S9. If the left movement of the selector S is permitted in step S10, the left movement of the selector S is executed in step S11. If not, the left movement of the selector S is not executed in step S12.

When the shift position detected by the shift position detection means Sc in step S5 is not the reverse position R , the vehicle speed detected by the vehicle speed detection means Sd in step S13 is equal to or higher than the predetermined value, or in step S14, the engine speed detection means Se. If the engine speed detected at step S15 is equal to or greater than the predetermined value, or if the differential rotation between the reverse driven gear 33 and the selector S is greater than the predetermined value in step S15, the in-gear of the reverse gear, that is, the left side of the selector S is determined in step S17. It prohibits movement, the if step S13~ the answer all YES in step S15, permits the leftward movement of the selector S Ru allowed to continue leftward movement of the selector S in step S16.

The reason why Steps S13 to S17 are provided is as follows. Since the shift position of the shift lever is arranged in the order of parking position P, reverse position R, neutral position N, drive position D, and low position L , for example, when shifting from drive position D to parking position P , the shift position the lever will be sure to pass through the reverse position R, also when the shift change from the drive position D in the reverse position R, sometimes accidentally get to the parking position P staggering through the reverse position R.

Such a shift lever when the selector S is activated at the moment of entering the reverse position R, the shift lever is a selector S at the moment of passing through the reverse position R to stop the operation, stop selector S is at the halfway position There is a possibility that. However, in this embodiment, even if the shift lever passes the reverse position R and enters the parking position P , if the differential rotation is less than the predetermined value, the operation of the selector S is continued until the end, An intermediate stop of the selector S can be prevented. Also during the movement selector S is toward the reverse position R, without leftward movement permission selector S under the conditions of the step S6~ step S8 is satisfied, so that the shift position is S17: If the reverse position R Selector Therefore, the intermediate stop of the selector S can be prevented by not prohibiting the left movement.

As described above, according to the present embodiment, when the differential rotation between the reverse driven gear 33 and the meshing engagement means S is less than the predetermined value and the shift position is the reverse position R, the selector S is operated. When the differential rotation between the reverse driven gear 33 and the selector S is greater than or equal to a predetermined value, the operation of the selector S is prohibited, so that the shift lever is moved to the reverse position R with the differential rotation increased due to an increase in engine speed or an increase in vehicle speed. Even if operated, the selector S does not operate, so that it is possible to prevent the durability of the selector S from being adversely affected. In particular, it is possible to improve the determination accuracy as compared with the case of determining whether or not the selector S can be operated based only on the engine speed and the vehicle speed, and reliably prevent the selector S from operating at an inappropriate timing.

Further, after the start of the operation of the selector S, the electronic control unit U continues the operation of the selector S if the shift position is the reverse position R even if the differential rotation becomes a predetermined value or more, and the shift position is the parking position. Even if the differential rotation is less than the predetermined value, the operation of the selector S is continued, so that the intermediate stop of the selector S can be prevented.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the differential rotation threshold value that prohibits the establishment of the reverse gear can be changed depending on the coolant temperature. That is, when the coolant temperature is low, the oil viscosity becomes high and a shift shock is likely to occur. Therefore, the shift shock can be more reliably prevented by setting the threshold value for the differential rotation low.

13 First input shaft (input shaft)
15 Output shaft 27 Reverse drive gear 33 Reverse driven gear 34 Reverse idle gear C4 4 speed-reverse clutch (hydraulic clutch)
E Engine (drive source)
P parking position
R reverse position S selector (meshing engagement means)
S1 Input shaft rotational speed detection means S2 Output shaft rotational speed detection means U Electronic control unit (shift control means)
W drive wheel

Claims (2)

The input shaft (13) to which the driving force from the driving source (E) is input, the output shaft (15) for outputting the driving force to the driving wheels (W), the input shaft (13), and the output shaft (15) A plurality of gears that mesh with each other, a hydraulic clutch (C4) that establishes a predetermined forward shift stage by coupling any of the plurality of gears to the input shaft (13), and the input shaft A reverse drive gear (27) provided on (13) and connectable to the input shaft (13) by the hydraulic clutch (C4); and meshing engagement means (S) provided on the output shaft (15). Schiff that the reverse driven gear couplable to the output shaft (15) (33), and the reverse idle gear (34) which connects said reverse drive gear (27) and said reverse driven gear (33), which is selected by the shift lever by And a position and speed control means in accordance with the running state of the vehicle performs control to shift the operation of the hydraulic clutch (C4) and the mating engagement means (S) (U),
The shift control means (U) engages the hydraulic clutch (C4) in the state where the reverse driven gear (33) is coupled to the output shaft (15) by the mesh engagement means (S) to perform reverse shift. In an automatic transmission for a vehicle that establishes a gear,
The shift control means (U), the calculates the differential rotation of the reverse driven gear (33) and said mating engaging means (S), the differential rotation is less than the predetermined value and the selected shift position The meshing engagement means (S) is operated when the reverse position (R) is set, and after the start of the operation, even if the differential rotation becomes a predetermined value or more, the selected shift position is the reverse position ( R), the operation of the meshing engagement means (S) is continued, and even if the selected shift position is the parking position (P), if the differential rotation is less than the predetermined value, automatic transmission for a vehicle according to claim Rukoto to continue the operation of the meshing engagement means (S). Input shaft rotational speed detection means (Sa) for detecting the input shaft rotational speed, and output shaft rotational speed detection means (Sb) for detecting the output shaft rotational speed,
The automatic transmission for a vehicle according to claim 1, wherein the shift control means (U) calculates the differential rotation from an input shaft rotation speed and an output shaft rotation speed.

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