JP5905580B2 - Control device and control method for automatic transmission - Google Patents

Description

  The present invention relates to a control device and control method for an automatic transmission that changes the gear ratio by controlling engagement and release of friction elements of the automatic transmission.

  The automatic transmission controls a plurality of planetary gears having a plurality of rotating elements and a plurality of friction elements that selectively stop the rotation of the rotating elements or connect the rotating elements to the engaged state or the released state. Thus, the gear ratio is changed.

  In the change ratio change control, there is a case where a so-called double change gear shift is performed in which the two friction elements are released and the two friction elements are fastened.

  In order to prevent or alleviate shocks at the end of a shift or at the end of a shift, and to reduce the time required for the shift, it is important to determine the order and timing of each friction element in the double changeover shift. It becomes.

  JP 2008-69892A controls the second release element to a half-engaged state while the first release element remains in the engaged state at the time of shifting from the first gear to the second gear, and thereafter , Gradually releasing the first release element and starting the engagement of the first engagement element, releasing the first release element and engaging the first engagement element; A shift control device for an automatic transmission that releases an element and engages a second engagement element is known.

    In JP2008-69892A, the engagement of the first engagement element, which is a friction element on the fastening side, is started after the second release element is made to slip in the state where the first release element is fastened. Control is performed so that the second engagement element is engaged after the release element is released.

  That is, the fastening of the first engaging element, the releasing of the second releasing element, and the fastening of the second engaging element are performed after releasing the first releasing element. This is because at least one friction element needs to be in an engaged state because the speed ratio is detected by detecting the speed ratio based on the difference between the input rotational speed and the output rotational speed.

  For this reason, if the release timing of the first release element is delayed, there is a problem that the entire progress of the shift is delayed and the shift time is increased.

  The present invention has been made in view of the above problems, and provides a control device and a shift control method for an automatic transmission capable of shortening a shift time at the time of a shift in a double switching shift of the automatic transmission. Objective.

According to an embodiment of the present invention, the present invention is applied to a control device for an automatic transmission that sets a predetermined gear stage by engaging and releasing a plurality of friction elements and shifts and outputs the rotational speed of a driving force source. Is done. In the automatic transmission control device, the friction element includes a first release element and a second release element that are released when shifting from the first shift stage to the second shift stage, a first engagement element that is fastened, and A second fastening element. When shifting from the first gear to the second gear, the first release element is controlled to the released state, the first fastening element is fastened, and the second fastening is completed after the first fastening element is fastened. Control to complete release of the element and completion of fastening of the second fastening element is performed, and when this shift is started, the first release element is immediately controlled to a fully released state where torque is not transmitted and the second release is performed. When the element is controlled to the slip state, the first fastening element and the second fastening element are controlled to the fastening state, and the second release element is controlled to the slip state, the torque capacity transmitted in the slip state increases as the vehicle speed increases. Control small .

Further, according to another embodiment of the present invention, the automatic transmission is controlled by changing the rotational speed of the driving force source by setting and releasing the plurality of friction elements to a predetermined shift speed and outputting the speed. Applied to the method. The friction element includes a first release element and a second release element that are released when shifting from the first speed to the second speed, and a first fastening element and a second fastening element that are fastened, When the shift from the first gear to the second gear is started, the procedure for immediately controlling the first release element to the fully released state where torque is not transmitted, and the first release element is controlled to the fully released state. is engaged at the first fastening element after, after engagement of the first engagement element is completed, the procedure performs control to complete the engagement of the control and the second fastening element to complete the release of the second release element, the second When the release element is controlled to the slip state, the procedure for controlling the torque capacity transmitted in the slip state to be smaller as the vehicle speed is higher;
Is provided.

  According to the above aspect, in the double change gearshift for releasing the first release element and the second release element and fastening with the first fastening element and the second fastening element, the first release element is immediately brought into a fully released state. Since the timing for starting the engagement / release control of the second release element, the first engagement element, and the second engagement element can be advanced, the shift time of the double change shift can be shortened.

FIG. 1 is a schematic configuration diagram of a vehicle equipped with a continuously variable transmission according to an embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating an example of a shift map according to the embodiment of this invention. FIG. 3 is an explanatory diagram of the transmission including the hydraulic control circuit according to the embodiment of the present invention. FIG. 4 is a flowchart of the control of the double change gear shift according to the embodiment of the present invention. FIG. 5 is a time chart of the control of the double change gear shift according to the embodiment of the present invention. FIG. 6A is a collinear diagram related to double change gear shifting according to the embodiment of the present invention. FIG. 6B is a collinear diagram related to the double change gear shift according to the embodiment of the present invention. FIG. 6C is a collinear diagram related to the double change gear shift according to the embodiment of the present invention. FIG. 6D is a collinear diagram related to the double change gear shift according to the embodiment of the present invention. FIG. 7 is an explanatory diagram showing torque fluctuations according to the embodiment of the present invention. FIG. 8 is an explanatory diagram of a shock in the double change gear shift according to the embodiment of the present invention. FIG. 9 is an explanatory diagram of the vehicle speed and the width of the rotation change before and after the shift according to the embodiment of the present invention.

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

  FIG. 1 is a skeleton diagram showing the configuration of the automatic transmission according to this embodiment. The automatic transmission according to the present embodiment is a stepped automatic transmission with 7 forward speeds and 1 reverse speed. The driving force of the engine Eg is input from the input shaft IP via the torque converter TC, and four planetary gears and 7 The rotational speed is shifted by the two friction elements and output from the output shaft OT. An oil pump OP is provided coaxially with the pump impeller of the torque converter TC, and is rotationally driven by the driving force of the engine Eg to pressurize the oil.

  The automatic transmission includes an engine controller (ECU) 10 that controls the drive state of the engine Eg, an automatic transmission controller (ATCU) 20 that controls the shift state of the automatic transmission, and the like based on output signals of the ATCU 20. A control valve unit (CVU) 30 for controlling the hydraulic pressure of the friction element is provided. The ECU 10 and the ATCU 20 are connected via a CAN communication line or the like, and share sensor information and control information with each other by communication.

  Connected to the ECU 10 are an APO sensor 1 that detects the amount of accelerator pedal operation by the driver, an engine speed sensor 2 that detects the engine speed, and a throttle sensor 7 that detects the throttle opening. The ECU 10 controls the fuel injection amount and the throttle opening based on the engine rotation speed and the accelerator pedal operation amount, and controls the rotation speed and torque of the engine.

  The ATCU 20 detects the first turbine rotation speed sensor 3 that detects the rotation speed of the first carrier PC1, the second turbine rotation speed sensor 4 that detects the rotation speed of the first ring gear R1, and the shift lever operation state of the driver. Inhibitor switch 6 is connected to select an optimum command shift speed based on vehicle speed Vsp and accelerator pedal operation amount APO in the D range, and a control command for achieving the command shift speed is output to CVU 30. The ATCU 20 calculates the rotational speed of the input shaft IP based on the detection values of the first turbine rotational speed sensor 3 and the second turbine rotational speed sensor 4. A method for calculating the rotational speed of the input shaft IP will be described later.

  Next, a transmission gear mechanism that transmits the rotation of the input shaft IP to the output shaft OT while shifting the speed will be described. In the transmission gear mechanism, a first planetary gear set GS1 and a second planetary gear set GS2 are sequentially arranged from the input shaft IP side to the axial direction output shaft OT side. Further, a plurality of clutches C1, C2, C3 and brakes B1, B2, B3, B4 are arranged as friction elements, and a plurality of one-way clutches F1, F2 are further arranged.

  The first planetary gear set GS1 includes a first planetary gear G1 and a second planetary gear G2, and the second planetary gear set GS2 includes a third planetary gear G3 and a fourth planetary gear G4. The first planetary gear G1 is a single pinion planetary gear having a first sun gear S1, a first ring gear R1, and a first carrier PC1 that supports a first pinion P1 meshing with both gears S1 and R1. The second planetary gear G2 is a single pinion planetary gear having a second sun gear S2, a second ring gear R2, and a second carrier PC2 that supports a second pinion P2 that meshes with both the gears S2, R2. The third planetary gear G3 is a single pinion planetary gear having a third sun gear S3, a third ring gear R3, and a third carrier PC3 that supports a third pinion P3 that meshes with both gears S3 and R3. The fourth planetary gear G4 is a single pinion planetary gear having a fourth sun gear S4, a fourth ring gear R4, and a fourth carrier PC4 that supports a fourth pinion P4 that meshes with both the gears S4 and R4.

  The input shaft IP is connected to the second ring gear R2 and inputs the rotational driving force from the engine Eg via the torque converter TC or the like. The output shaft OT is coupled to the third carrier PC3, and transmits the output rotational driving force to the driving wheels via a final gear or the like.

  The first connecting member M1 is a member that integrally connects the first ring gear R1, the second carrier PC2, and the fourth ring gear R4. The second connecting member M2 is a member that integrally connects the third ring gear R3 and the fourth carrier PC4. The third connecting member M3 is a member that integrally connects the first sun gear S1 and the second sun gear S2.

  The first planetary gear set GS1 is composed of four rotating elements, in which the first planetary gear G1 and the second planetary gear G2 are connected by a first connecting member M1 and a third connecting member M3. The second planetary gear set GS2 is composed of five rotating elements by connecting the third planetary gear G3 and the fourth planetary gear G4 by the second connecting member M2.

  In the first planetary gear set GS1, torque is input from the input shaft IP to the second ring gear R2, and the input torque is output to the second planetary gear set GS2 via the first connecting member M1. In the second planetary gear set GS2, when the input clutch C1 is engaged, torque is directly input from the input shaft IP to the second connecting member M2, and is input to the fourth ring gear R4 via the first connecting member M1, The input torque is output from the third carrier PC3 to the output shaft OT.

  The input clutch C1 is a clutch that selectively connects and disconnects the input shaft IP and the second connecting member M2. The direct clutch C2 is a clutch that selectively connects and disconnects the fourth sun gear S4 and the fourth carrier PC4.

  The H & LR clutch C3 is a clutch that selectively connects and disconnects the third sun gear S3 and the fourth sun gear S4. A second one-way clutch F2 is disposed between the third sun gear S3 and the fourth sun gear S4. Thus, when the H & LR clutch C3 is released and the rotation speed of the fourth sun gear S4 is higher than that of the third sun gear S3, the third sun gear S3 and the fourth sun gear S4 generate independent rotation speeds. Therefore, the third planetary gear G3 and the fourth planetary gear G4 are connected via the second connecting member M2, and each planetary gear achieves an independent gear ratio.

  The front brake B1 is a brake that selectively stops the rotation of the first carrier PC1. A first one-way clutch F1 is disposed in parallel with the front brake B1. The low brake B2 is a brake that selectively stops the rotation of the third sun gear S3. The 2346 brake B3 is a brake that selectively stops the rotation of the third connecting member M3 that connects the first sun gear S1 and the second sun gear S2. The reverse brake B4 is a brake that selectively stops the rotation of the fourth carrier PC4.

  Here, a method for calculating the turbine rotation speed, which is the rotation speed of the input shaft IP calculated in the ATCU 20 (input shaft rotation estimation means), will be described. The turbine rotation speed is based on the rotation speed of the first carrier PC1 that is a detection value of the first turbine rotation speed sensor 3 and the rotation speed of the second carrier PC2 that is a detection value of the second turbine rotation speed sensor 4. It calculates according to the following (1) Formula.

N _Input = (1 + λ ₁ / λ ₁ ) N _PC2 − (1 / λ ₁ ) N _PC1 (1)
N _Input represents the rotational speed of the input shaft IP, N _PC1 represents the rotational speed of the first carrier PC1, N _PC2 represents the rotational speed of the second carrier PC2, and λ ₁ represents the gear ratio. Gear ratio lambda ₁ is the ratio of the number of teeth Z _P1 of the number of teeth Z _R2 and the first pinion P1 of the second ring gear R2 as shown in the following equation (2).

λ ₁ = Z _R2 / Z _P1 (2)
The automatic transmission is configured as described above, and the gear position is switched between the first speed to the seventh speed based on the vehicle speed and the throttle opening according to the shift line of the shift map stored in advance. In the shift map, the shift state is determined when the driving state determined by the vehicle speed and the throttle opening straddles each upshift line or each downshift line.

  Next, the operation of the transmission gear mechanism will be described with reference to FIGS. Fig. 2 is a fastening table showing the engagement state of each friction element for each gear position. The circle indicates that the friction element is in the engagement state, and the circle indicates that the range position where the engine brake operates is selected. It is shown that the friction element is in a fastening state when being done. FIG. 3 is a collinear diagram showing a rotation state of each rotary member at each shift stage.

  In the first speed, only the low brake B2 is engaged, and the first one-way clutch F1 and the second one-way clutch F2 are engaged. When the engine brake is applied, the front brake B1 and the H & LR clutch C3 are further engaged.

  Since the rotation of the first carrier PC1 is stopped by the engagement of the first one-way clutch F1, the rotation input to the second ring gear R2 from the input shaft IP is decelerated by the first planetary gear set GS1, This rotation is output from the first connecting member M1 to the fourth ring gear R4. Further, since the rotation of the third sun gear S3 and the fourth sun gear S4 is restrained by engaging the second brake F2 and engaging the second one-way clutch F2, the rotation input to the fourth ring gear R4 is It is decelerated by the second planetary gear set GS2 and output from the third carrier PC3.

  That is, at the first speed, as shown in the collinear diagram of FIG. 3, the rotation of the input shaft IP is decelerated by the first planetary gear set GS1, further decelerated by the second planetary gear set GS2, and output from the output shaft OT. The

  In the second speed, the low brake B2 and the 2346 brake B3 are engaged, and the second one-way clutch F2 is engaged. Further, the H & LR clutch C3 is further engaged when the engine brake is applied.

  Since the rotation of the first sun gear S1 and the second sun gear S2 is restrained by engaging the 2346 brake B3, the rotation input to the second ring gear R2 from the input shaft IP is only performed by the second planetary gear G2. The speed is reduced, and this rotation is output from the first connecting member M1 to the fourth ring gear R4. Further, since the rotation of the third sun gear S3 and the fourth sun gear S4 is restrained by engaging the second brake F2 and engaging the second one-way clutch F2, the rotation input to the fourth ring gear R4 is It is decelerated by the second planetary gear set GS2 and output from the third carrier PC3.

  That is, at the second speed, as shown in the collinear diagram of FIG. 3, the rotation of the input shaft IP is decelerated by the first planetary gear set GS1, further decelerated by the second planetary gear set GS2, and output from the output shaft OT. The

  In the third speed, the low brake B2, the 2346 brake B3, and the direct clutch C2 are engaged.

  Since the rotation of the first sun gear S1 and the second sun gear S2 is stopped when the 2346 brake B3 is engaged, the rotation input to the second ring gear R2 from the input shaft IP is decelerated by the second planetary gear G2. This rotation is output from the first connecting member M1 to the fourth ring gear R4. Further, as the direct clutch C2 is engaged, the fourth planetary gear G4 rotates integrally. Therefore, the fourth planetary gear G4 is involved in torque transmission but not in deceleration. Further, since the rotation of the third sun gear S3 is stopped when the low brake B2 is engaged, the third ring is rotated from the fourth carrier PC4 rotating integrally with the fourth ring gear R4 via the second connecting member M2. The rotation input to the gear R3 is decelerated by the third planetary gear G3 and output from the third carrier PC3.

  That is, at the third speed, as shown in the collinear diagram of FIG. 3, the rotation of the input shaft IP is decelerated by the first planetary gear set GS1, and further decelerated by the third planetary gear G3 of the second planetary gear set GS2. And output from the output shaft OT.

  At the fourth speed, 2346 brake B3, direct clutch C2, and H & LR clutch C3 are engaged.

  Since the rotation of the first sun gear S1 and the second sun gear S2 is restrained by engaging the 2346 brake B3, the rotation input to the second ring gear R2 from the input shaft IP is only performed by the second planetary gear G2. The speed is reduced, and this rotation is output from the first connecting member M1 to the fourth ring gear R4. Since the second planetary gear set GS2 rotates as a result of engaging the direct clutch C2 and the H & LR clutch C3, the rotation input to the fourth ring gear R4 is directly output from the third carrier PC3. .

  That is, at the fourth speed, as shown in the collinear diagram of FIG. 3, the rotation of the input shaft IP is decelerated by the first planetary gear set GS1, and is not decelerated by the second planetary gear set GS2, and is decelerated from the output shaft OT. Is output.

  In the fifth speed, the input clutch C1, the direct clutch C2, and the H & LR clutch C3 are engaged.

  As the input clutch C1 is engaged, the rotation of the input shaft IP is directly input to the second connecting member M2. Further, since the second planetary gear set GS2 rotates as a result of engaging the direct clutch C2 and the H & LR clutch C3, the rotation of the input shaft IP is output from the third carrier PC3 as it is.

  That is, at the fifth speed, as shown in the nomogram of FIG. 3, the rotation of the input shaft IP is output as it is from the output shaft OT without being decelerated by the first planetary gear set GS1 and the second planetary gear set GS2. The

  In the sixth speed, the input clutch C1, the H & LR clutch C3, and the 2346 brake B3 are engaged.

  When the input clutch C1 is engaged, the rotation of the input shaft IP is input to the second ring gear and also directly input to the second connecting member M2. Since the rotation of the first sun gear S1 and the second sun gear S2 is stopped when the 2346 brake B3 is engaged, the rotation of the input shaft IP is decelerated by the second planetary gear G2, and the first connecting member M1 Output to the fourth ring gear R4.

  When the H & LR clutch C3 is engaged, the third sun gear S3 and the fourth sun gear S4 rotate integrally. Therefore, the second planetary gear set GS2 rotates the fourth ring gear R4 and the second connecting member M2. Is output from the third carrier PC3.

  That is, at the sixth speed, as shown in the collinear diagram of FIG. 3, a part of the rotation of the input shaft IP is decelerated in the first planetary gear set GS1, and is increased in the second planetary gear set GS2 to be output. Output from axis OT.

  In the seventh speed, the input clutch C1, the H & LR clutch C3, and the front brake B1 are engaged, and the first one-way clutch F1 is engaged.

  When the input clutch C1 is engaged, the rotation of the input shaft IP is input to the second ring gear R2 and directly to the second connecting member M2. Further, since the rotation of the first carrier PC1 is stopped by fastening the front brake B1, the rotation of the input shaft IP is decelerated by the first planetary gear set GS1, and this rotation is transmitted from the first connecting member M1. It is output to the 4-ring gear R4.

  When the H & LR clutch C3 is engaged, the third sun gear S3 and the fourth sun gear S4 rotate integrally. Therefore, the second planetary gear set GS2 rotates the fourth ring gear R4 and the second connecting member M2. Is output from the third carrier PC3.

  That is, at the seventh speed, as shown in the collinear diagram of FIG. 3, a part of the rotation of the input shaft IP is decelerated in the first planetary gear set GS1, and is increased in the second planetary gear set GS2, and output. Output from axis OT.

  At the reverse speed, the H & LR clutch C3, the front brake B1, and the reverse brake B4 are engaged.

  Since the rotation of the first carrier PC1 is stopped when the front brake B1 is engaged, the rotation of the input shaft IP is decelerated by the first planetary gear set GS1, and this rotation is transmitted from the first connecting member M1 to the fourth ring. It is output to the gear R4.

  When the H & LR clutch C3 is engaged, the third sun gear S3 and the fourth sun gear S4 rotate integrally, and when the reverse brake B4 is engaged, the rotation of the second connecting member M2 is stopped. In the two planetary gear set GS2, the rotation of the fourth ring gear R4 is transmitted in reverse to the fourth sun gear S4, the third sun gear S3, and the third carrier PC3, and is output from the third carrier PC3.

  That is, at the reverse speed, as shown in the collinear diagram of FIG. 3, the rotation of the input shaft IP is decelerated in the first planetary gear set GS1, reversed in the second planetary gear set GS2, and output from the output shaft OT. The

  The automatic transmission is configured as described above, and is switched to a desired gear position between 1st speed and 7th speed according to a shift line set based on the vehicle speed and the throttle opening.

  Next, the double change shift in the automatic transmission according to the embodiment of the present invention will be described.

  The double-changing shift is a shift control for releasing the two friction elements in the engaged state and engaging the two friction elements in the released state. Referring to the engagement table shown in FIG. 2, for example, when the gear stage shifts from the 7th speed to the 4th speed, the front brake B1 and the input clutch C1 are released, and the direct clutch C2 and the 2346 brake B3 are engaged. By doing so, a shift is performed.

  Here, in the case of shift control in which one of the four friction elements (front brake B1, input clutch C1, direct clutch C2, and 2346 brake B3) is released and one friction element is engaged, Since there is a completely engaged friction element among the elements, it is possible to calculate the gear ratio by detecting the input rotational speed (engine rotational speed) and the output rotational speed of the automatic transmission, respectively. Can be detected. That is, by detecting the differential rotation (slip amount) of the release-side friction element based on this rotational speed difference, the gear ratio during the shift can be detected, and the timing for engaging the engagement-side friction element is controlled appropriately. This can prevent shift shock.

  On the other hand, in the case of double change gear shifting, it is necessary to perform control of releasing two release elements and fastening two fastening elements. Here, if the two release elements are released almost simultaneously during the shift, there will be no fully engaged friction element among the four friction elements, and the gear ratio is determined from the relationship between the input rotation speed and the output rotation speed. Cannot be detected. That is, since the progress of the shift cannot be detected from the gear ratio, it is not possible to determine the timing of engagement and release of each friction element. Therefore, conventionally, in order to detect the speed ratio and detect the progress of the speed change, it is necessary that at least one friction element is maintained in the engaged state. For example, the first release element on the release side is maintained in the engaged state, and then the first release element is released, and then the engagement and release control of the other friction elements is performed. For this reason, in the conventional double changeover shift, the shift time is long.

  Therefore, in the embodiment of the present invention, as described below, in the double change gear shift, the first release element on the release side is immediately released and controlled based on the rotational speed difference of the first release element. The degree of progress of the shift was determined, and control was performed so that each friction element was engaged and released.

  FIG. 4 is a flowchart of the control of the double change gear shift according to the embodiment of the present invention.

  The flowchart shown in FIG. 4 is executed when the ATCU 20 determines to perform a double change gear shift.

  Note that the double change gear shift according to the present embodiment is performed when the input torque is increased, for example, when the accelerator pedal is depressed from a state where the input torque to the automatic transmission is small or substantially zero. Double shifting is not performed at the time of shifting when the accelerator pedal is further depressed after the input torque to the automatic transmission is large. When the input torque is greater than 0, for example, when the required torque is increased from a state where the accelerator pedal is depressed greatly (accelerator pedal is depressed), the torque rises quickly at the start of the shift, so that the shift proceeds. It becomes faster, and the hydraulic pressure supply such as charge control of the friction element on the engagement side is not in time, and the engagement shock increases. Therefore, when the required torque is increased from the state where the input torque is greater than 0 (the accelerator pedal is stepped on), the double change gear shift is not performed for the purpose of suppressing the shock.

  First, the ATCU 20 determines the release-side and engagement-side friction elements in the double change gear shift (S110). Here, the two friction elements on the release side are respectively referred to as a first release element and a second release element, and the two friction elements on the engagement side are respectively referred to as a first engagement element and a second engagement element. How to determine these friction elements is determined based on the fastening table of FIG. 2 after determining the release-side first release element and the second release element as will be described later, and the corresponding first fastening elements. And the second fastening element are determined.

  After the process of step S110, the ATCU 20 executes the processes of steps S120, S210, S310, and S410, which will be described below, in parallel at substantially the same time.

  In step S120, the ATCU 20 controls to release the first release element to the fully released state immediately. Specifically, the ATCU 20 reduces the instruction value to the first release element in a pulse manner from the complete engagement state to the complete release state. As a result, the CVU 30 is commanded so that the hydraulic pressure supplied to the first release element is drained and the torque transmission capacity of the first release element becomes zero. As a result, the first release element is immediately controlled from the fastened state to the fully released state.

  Next, the ATCU 20 detects the differential rotation in the first release element, and determines whether or not the progress of the rotation change in the first release element is equal to or greater than a predetermined progress (S130). Specifically, when the degree of progress of the rotation change in the first release element advances and the difference rotation in the first fastening element becomes zero or a difference rotation that does not cause a shock even when the first fastening element is fastened, the degree of progress. Is determined to be greater than or equal to a predetermined degree of progress. The differential rotation in the first engagement element is calculated from the rotational speeds of the first ring gear R1, the first carrier PC1, and the first sun gear S1 in the first planetary gear G1. Specifically, the rotational speed of the first carrier PC1 is detected based on the first turbine rotational speed sensor 3, the rotational speed of the first ring gear R1 is detected based on the second turbine rotational speed sensor 4, and the first planetary gear is detected. The rotational speed of the first sun gear S1 is calculated from the gear ratio of G1. Since the first engagement element (2346 brake B3) is connected to the first sun gear S1, the rotational speed of the first sun gear S1 is the differential rotation in the first engagement element.

  When the progress of the rotation change in the first release element is less than the predetermined progress, step S130 is repeated, and the process waits while controlling the first release element to the released state. When the progress degree of the rotation change in the first release element becomes equal to or higher than the predetermined progress degree, the process proceeds to step S140, and the ATCU 20 sets the first flag. Thereafter, the processing from step S120 to S140 is temporarily terminated, and control from step S210, S310, or S410 is executed.

  In step S210, the ATCU 20 performs charge control as preparation for starting fastening of the first fastening element. The charge control is control in which the control hydraulic pressure of the first fastening element in the released state is once increased to a predetermined value, and the piston of the first fastening element is touched to reduce the clearance between the friction elements. After the charge control, the ATCU 20 controls the control hydraulic pressure of the first fastening element to a standby state for waiting for fastening (S220).

  Next, the ATCU 20 determines whether or not the first flag and the third flag are established (S230). When either one of the first flag and the third flag is not established, the process returns to step S220, and the first fastening element is maintained in the standby state.

  When it is determined that both the first flag and the third flag are established, the process proceeds to step S240, and a command is issued to the CVU 30 so that the first fastening element is in the fastening state. Thereby, the first fastening element is controlled to the fastening state. Thereafter, the processing from step S210 to S240 is temporarily terminated, and control from step S110, S310, or S410 is executed.

  In step S310, the ATCU 20 starts releasing control of the second releasing element. Specifically, the ATCU 20 instructs the CVU 30 to gradually drain the hydraulic pressure supplied to the second release element to reduce the torque transmission capacity of the second release element. Accordingly, the second release element is controlled from the fastening state to the release state.

  Next, the ATCU 20 detects the differential rotation in the second release element, and determines whether or not the second release element has started slipping (S320). If it is determined that the second release element has not slipped, the process returns to step S310 and waits with the release control of the second release element.

  When it is determined that the second release element has started slipping, the process proceeds to step S330, and the ATCU 20 establishes a third flag (S330). The slip (differential rotation) of the second release element is detected by the engine rotation speed sensor 2 and a rotation speed sensor (for example, the second turbine rotation speed sensor 4) provided in the automatic transmission.

  Next, the ATCU 20 continues the release control of the second release element started in step S310 (step S340), detects the differential rotation in the second release element, and determines the progress of the rotational change in the second release element. It is determined whether or not a predetermined degree of progress has been reached (S350). Specifically, when the degree of progress of the rotation change in the second release element progresses and the difference rotation in the second fastening element becomes zero or a difference rotation that does not cause a shock even when the second fastening element is fastened, the degree of progress. Is determined to have reached a predetermined degree of progress.

  When the progress degree of the rotation change in the second release element is less than the predetermined progress degree, step S340 is repeated, and the process waits with the control to the release state of the second release element. When the progress degree of the rotation change in the second release element is equal to or greater than the predetermined progress degree, the process proceeds to step S360, and the ATCU 20 sets the fourth flag. Thereafter, the processing from step S310 to S360 is temporarily terminated, and control from step S110, S210, or S410 is executed.

  In step S410, the ATCU 20 performs charge control as preparation for starting the fastening of the second fastening element. After the charge control, the ATCU 20 controls the control hydraulic pressure of the second fastening element to a standby state for fastening (S420). The charge control at this time is the same as S210 described above.

  Next, the ATCU 20 determines whether or not the second flag and the fourth flag are established (S430). When either one of the second flag and the fourth flag is not established, the process returns to step S420, and the second fastening element is maintained in the standby state.

  When it is determined that both the second flag and the fourth flag are established, the process proceeds to step S440, and a command is issued to the CVU 30 so that the second fastening element is in the fastening state. Thereby, the second fastening element is controlled to the fastening state.

  When the 2nd fastening element will be in a fastening state, control by this flowchart will be completed.

  By such control, the first release element and the second release element are released, and the first engagement element and the second engagement element are engaged. As a result, the double change gear shifting is completed.

  FIG. 5 is a time chart of the double change gear shift according to the embodiment of the present invention.

  In FIG. 5, the vertical axis represents command values of the first release element, the second release element, the first fastening element, and the second fastening element, and the horizontal axis represents time. The command value is a hydraulic pressure command value for controlling the fastening force (torque transmission capacity) of these fastening elements.

  In FIG. 5, the two-dot chain line indicates the first release element, the chain line indicates the second release element, the one-dot chain line (thin line and thick line) indicates the first fastening element, and the solid line indicates the second fastening element.

  When the ATCU 20 decides to perform the double change gear shift at the timing t0, the first engagement element and the second release element on the release side, and the first engagement element and the second engagement element on the engagement side in the double change gear change. To decide.

  In response, the ATCU 20 executes the processes from Steps S120, S210, S310, and S410 of FIG. 4 in parallel at the timing t1.

  First, in step S120, the ATCU 20 controls the first release element to the fully released state. At this time, the command value is decreased from the engaged state to the lowest value (for example, zero) so that the first release element is immediately in the complete release state. The ATCU 20 detects the progress of the rotational change of the first release element based on the command (S130), and determines that the rotational change has become larger than a predetermined value, that is, the first release element has been released. The first flag is established (S140).

  In step S210, the ATCU 20 performs charge control of the first fastening element. In the charge control, the control value of the first fastening element is once increased to a predetermined magnitude and then set to a control value lower than this control value. Thereby, the charging of the first fastening element is completed (timing t2). After the completion of the charge control, the command value is set in a standby state to wait (step S220, timing t3).

  In step S310, the ATCU 20 controls the second release element to the release side. Since the second release element has a large share ratio for transmitting torque, the second release element is not immediately controlled to be released, but is controlled to slip.

  At this time, if it is determined that the second release element has started slipping due to the rotation change of the second release element, the third flag is established. Furthermore, when it is determined that the rotational change of the second release element has become larger than the predetermined value, that is, the second release element has reached the predetermined slip amount, the fourth flag is established.

  In step S410, the ATCU 20 performs charge control of the second fastening element (timing t2). After completion of the charge control, the command value is set in a standby state and waits (step S420, timing t3).

  Next, in the determination of step S230 of the first engagement element, when it is determined that both the first flag and the third flag are established, that is, the first release element is in the released state, and the second release element is slipped. When it determines with having started, ATCU20 controls a 1st fastening element to a fastening state (timing t4). At this time, the second flag is established.

  Control is performed based on the difference in rotational speed between the first release element and the second release element until the first engagement element is in the engaged state, but after the first engagement element completes the engagement, the gear ratio is determined. Therefore, control is performed based on this speed ratio (difference between input rotation speed and output rotation speed).

  In the determination of step S430 of the second engagement element, when it is determined that both the second flag and the fourth flag are established, that is, the first engagement element is in an engagement state, and the slip amount of the second release element is a predetermined amount. When it determines with it being above, ATCU20 controls a 2nd fastening element to a fastening state (timing t5).

  Thereby, the first and second fastening elements complete the fastening, and the first and second release elements are released. As a result, the double change gear shift is completed (timing t6).

  When the first fastening element is fastened (timing t4, step S240 in FIG. 4), the first fastening element is not controlled immediately, but is controlled to the maximum fastening amount after the first fastening element is once controlled to the slip state. Then, the fastening state may be controlled (indicated by a fine dotted line). In this way, when the first fastening element is fastened, for example, even if the rotational speed difference of the first fastening element is not zero or near zero due to variations in hydraulic pressure or parts system, the first fastening element is fastened once in a slip state. Therefore, the fastening shock can be suppressed.

  FIG. 6A to FIG. 6D are collinear diagrams showing the rotation states of the rotating members related to the double change gear shift according to the embodiment of the present invention.

  FIG. 6A shows a state where the gear position is 7th. FIG. 6D shows a state where the gear position is the fourth speed. FIG. 6B and FIG. 6C show the process of double change gear shift in the shift from the seventh speed to the fourth speed.

  In FIG. 6A, the rotation of the input shaft IP starts from the input clutch C1 (indicated by a diamond ◇ in the figure) to the engaged state of the front brake B1 (indicated by a triangle Δ in the figure) and the H & LR clutch C3 (indicated by a square □ in the figure). Is output to the output shaft OT. At the seventh gear, the front brake B1, the input clutch C1, and the H & LR clutch C3 are engaged.

  Consider a case where the gear position is changed to 4th gear from this state. When shifting the gear stage from the 7th gear to the 4th gear, as shown in the engagement diagram of FIG. 2, the engaged front brake B1 and the input clutch C1 are disengaged, and the disengaged direct clutch C2 (black in the figure). Circle 2) and 2346 brake B3 (indicated by a double circle ◎ in the figure) are controlled to be engaged. That is, a double change gear shift is performed.

  When the ATCU 20 determines to perform the double change gear shift, the ATCU 20 determines the front brake B1 and the input clutch C1 as the first release element and the second release element, respectively. Further, the direct clutch C2 and the 2346 brake B3 are determined as the first engagement element and the second engagement element, respectively.

  Then, as in the flowchart described above, the ATCU 20 releases the first and second release elements.

  Specifically, the front brake B1 that is the first release element is immediately controlled to the released state, and the input clutch C1 that is the second release element is controlled to the slip state. As a result, the rotational speed of the input shaft IP increases due to the slip of the input clutch C1 while maintaining the collinear inclination of the input shaft IP and the input clutch C1 (FIG. 6B).

  Here, when the progress of the rotation change of the front brake B1 becomes equal to or higher than a predetermined progress, that is, to control the 2346 brake B3 as the first engagement element to the engagement state based on the rotation speed of the input shaft IP. The first flag is established when the rotation speed is sufficient. That is, in FIG. 6B, when the rotational speed of the input shaft IP increases, the collinear line with the input clutch C1 approaches the 2346 brake B3, and the rotation speed is high enough to prevent a shock when the 2346 brake B3 is engaged. First, the first flag is established. Further, the third flag is established when the input clutch C1 enters a predetermined slip state. Thereby, 2346 brake B3 which is a 1st fastening element is controlled to a fastening state. As a result, the rotation of the input shaft IP is locked by the 2346 brake B3 (FIG. 6C).

  Further, the second flag is established when the 2346 brake B3 is in the engaged state, and the fourth flag is established when the progress of the rotational change of the input clutch C1 is equal to or greater than the predetermined progress. When the fourth flag is established, the direct clutch C2, which is the second engagement element, is controlled to the engaged state. Thereby, the inclination between the output shaft OT and the direct clutch C2 becomes substantially horizontal.

  As a result, the direct clutch C2 is engaged and the gear position is changed to the fourth speed (FIG. 6D).

  Next, determination of the first release element and the second release element will be described.

  As described above, in the present embodiment, the first release element is set as the front brake B1, and the second release element is set as the input clutch C1. Here, for example, a case where the first release element is set as the input clutch C1 and the front brake B1 is set as the second release element is considered.

  In this case, in FIG. 6A, first, the input clutch C1 that is the first release element is set to the released state, and the front brake B1 that is the second release element is controlled to the slip state. When controlled in this way, the movement of the collinear line of the input shaft IP and the input clutch C1 depends on the slip amount of the front brake B1. That is, since the rotation of the input shaft IP is difficult to change, the rotation speed of the 2346 brake B2 is difficult to decrease, and the shock increases when the 2346 brake B3 is engaged.

  On the other hand, when the first release element is set as the front brake B1 and the second release element is set as the input clutch C1 as described above, the collinear line between the input shaft IP and the input clutch C1 is in the released state. Therefore, the input shaft IP is likely to change. Therefore, the rotational speed difference in the 2346 brake B3 can be reduced, and the shift shock can be suppressed when the 2346 brake B3 is engaged.

  FIG. 7 is an explanatory diagram showing torque fluctuations when the shift speed of the embodiment of the present invention is changed from the seventh speed to the fourth speed.

  In FIG. 7, the horizontal axis represents the input torque of the transmission, and the vertical axis represents the change in the rotational speed of the input shaft IP (input shaft angular acceleration). When the shift speed is 7th speed, it is indicated by a diamond ◇ in the figure, when the front brake B1 as the first release element is released, indicated by a square □ in the figure, and when the input clutch C1 as the second release element is released. A middle triangle Δ indicates that the front brake B1 and the input clutch C1 are released at the same time.

  When the gear stage is 7, each friction element is in the engaged state, so that the rotation change of the input shaft IP does not occur with respect to the change of the input torque.

  Here, when the input clutch C1 is released, the rotation of the input shaft IP changes greatly with respect to the change of the input torque. In other words, the input clutch C1, which is the second release element, has a large torque sharing ratio at the seventh gear position.

  On the other hand, when the front brake B1 is released, the rotational change of the input shaft IP is small with respect to the change of the input torque. That is, the front brake B1, which is the first release element, has a small torque sharing ratio at the seventh gear position.

  Therefore, in the double change gear shifting, the first release element is set to the front brake B1 having a small torque sharing ratio, and the second release element is set to the input clutch C1 having a large torque sharing ratio. By setting in this way, even if the front brake B1 that is the first release element is immediately controlled to the released state, the torque is transmitted by the input clutch C1 that is the second release element, so that the rotation of the engine Eg can be prevented. Double shift gear shifting can be performed while suppressing the rise.

  As shown in FIG. 1, the input clutch C1 is located between the first planetary gear set GS1 located on the input side and the second planetary gear set GS2 located on the output side. In other words, the two planetary gear sets act so as to connect the torque, and the torque sharing ratio is large.

  Next, the predetermined degree of progress of the rotation change in the second release element in step S350 of the flowchart of FIG. 4 will be described.

  FIG. 8 is an explanatory diagram of a shock that occurs when the 2346 brake B3 is engaged in the double change over speed according to the embodiment of the present invention.

  In FIG. 8, the vertical axis indicates the magnitude of shock when the 2346 brake B3 is engaged, and the horizontal axis indicates the torque capacity of the 2346 brake B3.

  In FIG. 8, the magnitude of the shock of the 2346 brake B3 when the input clutch C1 is engaged (indicated by a square □ in the figure) and the magnitude of the shock of the 2346 brake B3 when the input clutch C1 is in the slip state (Indicated by diamonds in the figure).

  When the input clutch C1 is in the engaged state, the magnitude of the shock when the 2346 brake B3 is engaged increases with respect to the change in torque capacity when the 2346 brake B3 is engaged. On the other hand, when the input clutch C1 is in the slip state, the magnitude of the shock at the time of engagement of the 2346 brake B3 is smaller than the engagement state with respect to the change in torque capacity when the 2346 brake B3 is engaged. Yes.

  Due to such characteristics, for example, when the magnitude of the shock at the time of engagement permitted for the 2346 brake B3 is in the range of 0.02 to -0.02 [G], The 2346 brake B3 can be engaged with a wider torque capacity.

  Therefore, in step S320 of the flowchart of FIG. 4 described above, when the slip amount of the input clutch C1 becomes sufficient, the third flag is established, and the 2346 brake B3, which is the first engagement element, is controlled to be engaged. The fastening shock of the friction element can be prevented.

  Note that the slip amount of the input clutch C1, which is the second release element, may be changed according to the vehicle speed. That is, the torque capacity transmitted when the input clutch C1 is in the slip state is changed based on the vehicle speed.

  FIG. 9 is an explanatory diagram of the vehicle speed and the width of the rotation change before and after the shift according to the embodiment of the present invention.

  The example shown in FIG. 9 shows the width of the rotation change before and after the shift from the first shift stage to the second shift stage at the low vehicle speed (50 km / h) and the first shift stage at the high vehicle speed (100 km / h). The width of the rotation change before and after the shift to the second shift stage is shown. It is assumed that the first speed is 7th and the gear ratio is 1.0, the second speed is 4th and the gear ratio is 2.0.

  Referring to FIG. 9, at a low vehicle speed, the rotational speed of the engine Eg at the first shift stage is 1000 [rpm], and at the second shift stage, the rotational speed of the engine Eg is 2000 [rpm]. The width of the rotation change before and after the shift is 1000 [rpm].

  On the other hand, when the vehicle speed is high, the rotational speed of the engine Eg at the first gear is 2000 [rpm], and at the second gear, the rotational speed of the engine Eg is 4000 [rpm]. The width of the rotation change before and after the shift is 2000 [rpm].

  Therefore, when the vehicle speed is higher than when the vehicle speed is low, the width of the rotation change before and after the shift is approximately twice as large.

  This indicates that the change in rotation is greatly different because the vehicle speed is different even in the same shift control. In the double change gear shift, when the shift time is made the same regardless of the vehicle speed, it is necessary to change the rotation during the shift in the same time. In other words, when the vehicle speed is high, it is necessary to control the rotation change to be greater, so the second release element reduces the torque transmission capacity in the slip state.

  In the double-changing shift according to the present embodiment, the rotational change during the shift control is performed by performing slip control on the second release element. Therefore, the amount of slip when the second release element is in a slip state, that is, the torque capacity transmitted by the second release element is controlled to be smaller as the vehicle speed is higher, so that the rotation can be easily changed. The shift time can be controlled to be the same.

  The slip amount of the second release element may be variable according to the progress of the shift. That is, when the progress of the shift is fast, the slip amount may be controlled to increase the torque capacity, and when the progress of the shift is slow, the slip amount may be controlled to reduce the torque capacity. By controlling in this way, it is possible to control the change in the transmission speed due to the hydraulic pressure and the variation of each friction element.

  As described above, in the embodiment of the present invention, automatic shifting is performed by shifting the rotational speed of the engine Eg, which is a driving force source, to output by setting a predetermined gear stage by fastening and releasing a plurality of friction elements. The present invention relates to an ATCU 20 that is a control device of a machine. The friction element has a first release element and a second release element that are released when a double shift is performed from the first shift stage to the second shift stage, and a first fastening element and a second fastening element that are fastened. . When the ATCU 20 shifts from the first shift speed to the second shift speed, the ATCU 20 controls the first release element to the released state and then fastens the first fastening element, and after the fastening of the first fastening element is completed The control for completing the release of the second release element and the control for completing the fastening of the second fastening element are performed. When the shift is started, the first release element is controlled to a fully released state in which torque is not immediately transmitted, and the second release element is controlled to a slip state, and the first fastening element and the second fastening element are fastened. To control.

  By controlling in this way, the first release element and the second release element are released, and the first release element is immediately brought into the fully released state in the double change gear shift that is fastened to the first fastening element and the second fastening element. Since the control is performed, the shift time can be shortened.

  At the time of shifting, the first release element is immediately controlled to a fully released state. In this control, the instruction value to the first release element is decreased in a pulse manner from the fully engaged state to the fully released state (by completely draining the hydraulic pressure) to release the first release element as soon as possible. Is what you do. This is different from the control in which the first release element is in the fully released state after the period during which the first release element is controlled in the engaged state as in the prior art. Instead of maintaining the first release element in the engaged state as in the prior art, it is conceivable to perform control to make the fully released state after a period of maintaining in the slip state, but this is also different from such control.

  In the first gear, each friction element is set such that the torque transmitted by the first release element is larger than the torque transmitted by the second release element.

  Usually, shock is increased when the engagement control is performed in a state where the rotational speed difference of the friction element on the engagement side is large. Further, when the engine speed increases, the speed of change of the rotational speed difference of the friction element on the engagement side is increased, and it is difficult to perform the engagement when the rotational speed difference with a small shock is zero or near zero. On the other hand, by transmitting torque with the second release element having a large torque sharing ratio in the slip state, it is possible to suppress the engine speed from rising. Thereby, since the change speed of the rotational speed difference of the friction element on the engagement side can be reduced and the rotational speed difference can be engaged at or near zero, the shock can be reduced.

  When the second release element is controlled to the slip state, the higher the vehicle speed, the smaller the torque transmitted in the slip state. Therefore, the shift time can be made constant regardless of the vehicle speed.

  After the first fastening element is fastened, the second fastening element is fastened. The first fastening element is a rotating member that rotates and changes with the release of the first release element after the first release element starts the release control. For example, the fastening control is performed when the input shaft IP) exceeds a predetermined rotational change.

  During the double change gear shift, the first and second release elements and the first and second engagement elements are not in the engaged state, so the gear ratio during the shift is not determined, and the shift proceeds based on the gear ratio during the shift. The degree cannot be detected. For this reason, the timing which fastens a fastening element conventionally cannot be controlled. On the other hand, in the embodiment of the present invention, the fastening timing can be controlled based on the amount of change in the rotational speed of the rotating member as the first releasing element is released.

  In the fastening of the first fastening element, by setting the second release element in the slip state, it is possible to reduce the shock due to the fastening even when differential rotation occurs in the first fastening element.

  Since the second fastening element is fastened after fastening the first fastening element, and the second fastening element is controlled to the fastening state after the second releasing element is controlled to the slip state, the rotational speed difference in the second releasing element Is controlled to be small, so that a shock at the time of fastening of the second fastening element can be suppressed.

  When performing the fastening control of the first fastening element, the fastening control is performed with a fastening force smaller than the maximum fastening force of the first fastening element, so that a shock when fastening the first fastening element can be suppressed.

  When the input torque to the automatic transmission is greater than 0 and the required torque to the driving force source increases, the double changeover shift from the first gear to the second gear is prohibited. That is, in the shift from the first gear to the second gear by increasing the accelerator pedal when the input torque is large, the torque rises quickly at the start of the gear shift, and the first and second release elements are moved at the desired timing. It becomes difficult to fasten and the shock cannot be suppressed. Therefore, in such a state, the double change shift is prohibited and priority is given to suppression of shock.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea. For example, the first release element is released immediately with the start of shifting, but the present invention is not limited to this, and the first releasing element may be released after a predetermined time has elapsed since the start of shifting.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

This application claims the priority based on Japanese Patent Application No. 2012-177561 for which it applied to Japan Patent Office on August 9, 2012. As shown in FIG. The entire contents of these applications are incorporated herein by reference.

Claims (7)

In a control device for an automatic transmission that sets and shifts the rotational speed of a driving force source by setting and releasing a plurality of friction elements to a predetermined gear stage,
The friction element has a first release element and a second release element that are released when shifting from the first speed to the second speed, and a first fastening element and a second fastening element that are fastened,
When shifting from the first gear to the second gear, the first release element is controlled to the released state, and then the first fastening element is fastened, and the fastening of the first fastening element is completed. From the above, control to complete the release of the second release element and control to complete the fastening of the second fastening element,
When the shift is started, the first release element is immediately controlled to a fully released state that does not transmit torque, and the second release element is controlled to a slip state, and then the first fastening element and the second release element are controlled. Control the fastening element to the fastening state ,
The control device for an automatic transmission that controls the torque capacity transmitted in the slip state to be smaller as the vehicle speed is higher when the second release element is controlled to the slip state . The automatic transmission control device according to claim 1,
The control apparatus for an automatic transmission in which the torque transmitted by the second release element is larger than the torque transmitted by the first release element in the first shift stage. A control device for an automatic transmission according to claim 1 or 2,
Fastening the second fastening element after fastening the first fastening element;
The first fastening element includes a change amount of a rotation speed of a rotating member that rotates with the release of the first release element and the second release element after the first release element is started to be controlled to be released. A control device for an automatic transmission that is controlled to be engaged based on a slip state of the automatic transmission. A control device for an automatic transmission according to claim 3,
The automatic transmission control device, wherein the first engagement element is controlled to be in an engagement state based on a slip state of the second release element . A control device for an automatic transmission according to any one of claims 1 to 4,
Fastening the second fastening element after fastening the first fastening element;
The control device for an automatic transmission, wherein the second engagement element is controlled to be in an engagement state based on a change amount of a rotation speed of a rotating member that rotates with the release of the second release element . A control device for an automatic transmission according to any one of claims 1 to 5,
The control device for an automatic transmission , wherein when controlling the first fastening element to the fastening state, the fastening state is controlled with a fastening force smaller than a maximum fastening force of the first fastening element .   In a control method of an automatic transmission that sets a predetermined shift stage by engaging and releasing a plurality of friction elements, and shifts and outputs a rotational speed of a driving force source.
  The friction element has a first release element and a second release element that are released when shifting from the first speed to the second speed, and a first fastening element and a second fastening element that are fastened,
  When the shift from the first shift stage to the second shift stage is started, the first release element is immediately controlled to a fully released state where torque is not transmitted, and the second release element is set to a slip state. Procedures to control and
  After the first release element is controlled to the fully released state and the second release element is controlled to the slip state, the first fastening element is fastened, and the fastening of the first fastening element is completed, A procedure for performing control to complete the release of the second release element and control to complete the fastening of the second fastening element;
  A procedure for controlling the torque capacity transmitted in the slip state to be smaller as the vehicle speed is higher when the second release element is controlled to the slip state;
An automatic transmission control method comprising:

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