JP2007177922A - Control device and control method for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To determine gear shift points (shift down/up points) so that economical power running operation is performed. <P>SOLUTION: A transmission controller 13 checks on whether a brake signal is outputted from a hydraulic switch 19 (S41) or whether an accelerator pedal operation signal is outputted from an accelerator pedal 17 (S43). The controller also checks on whether any engine mode signal is outputted from a mode selector switch SW21 (S45). When the controller determines that the accelerator pedal operation signal is outputted and the accelerator pedal 17 is operated, it sets one of high power/economy modes according to the selection by a driver. When the controller determines that the accelerator pedal 17 is not operated, it sets the traveling mode in the retarder mode when the brake signal is turned on, and sets it in the coasting mode when the brake signal is not turned on. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device and method for an automatic transmission such as a vehicle, and more particularly to control of the number of rotations (shift point) for up / down shift.

  Japanese Utility Model Publication No. 63-118448 has two types of driving patterns, a normal pattern suitable for economic driving and a power pattern in which the shift switching vehicle speed is set higher than the normal pattern, and the accelerator pedal depression speed of the driver. An automatic shift control that automatically selects a running pattern according to the above is disclosed. Japanese Patent Application Laid-Open No. 2004-347003 discloses an automatic shift control that automatically shifts down with a smaller accelerator pedal depression amount if the engine speed is lower, for example, in FIG.

Japanese Utility Model Publication No. 63-118448 JP 2004-347003 A

  In work vehicles such as dump trucks, liquid-cooled brakes are preferably used as retarders. The retarder capacity depends on the coolant flow rate, which depends on the number of revolutions of the engine that drives the pump that discharges the coolant. That is, the higher the engine speed, the higher the retarder capability. Therefore, in a vehicle that employs a liquid-cooled brake, the accelerator pedal is in an open state (accelerator off) in addition to the travel mode in which the accelerator pedal is depressed and the power running operation is performed as in the normal / power pattern described above. A travel mode that is automatically selected is added, and in the travel mode when the accelerator is off, the speed at which the downshift is performed (shift down point) is set higher than that of the travel mode for power running Conventionally, automatic shift control has been adopted. With this control, when the accelerator is off, the engine speed is maintained higher than during powering operation, and high retarder capability is ensured.

  However, in the travel mode when the accelerator is off, the shift down point is set to a high value, and in the above-mentioned power running mode, if the engine speed is lower, the shift down is automatically performed with a smaller accelerator pedal depression amount. When combined with the control of performing, the following problems may occur when economical power running is performed at a low engine speed. That is, if the driver temporarily removes his or her foot from the accelerator pedal while performing such a power running operation, the control device recognizes this state as the accelerator off, and changes the driving mode from the power running mode. Since the mode is automatically switched to the accelerator-off mode, and the shift-down point is raised accordingly, the shift-down may be performed immediately. As a result of this downshift, the engine speed increases and economical power running cannot be continued.

  Therefore, an object of the present invention is to determine a shift point (shift down / up point) so that economical power running can be performed.

  In the automatic transmission control device according to the first aspect of the present invention, the first traveling mode which is the traveling mode when the acceleration device (17) is operated, and the acceleration device (17) is not operated. A second travel mode that is a travel mode when the retarder mode is a travel mode when the second travel mode is intended to increase the retarder capacity, and the acceleration device (17) A coasting mode, which is a traveling mode when it is not operated or intended to be able to continue operation at a low engine speed when the operation amount of the acceleration device (17) is extremely small, The travel mode determining means (13) for determining whether the travel mode is the first or second travel mode, and the travel mode determining means (13) are determined to be the first travel mode. If the first A first variable control means (13) for variably controlling a shift-up point and a shift-down point in the travel mode within a predetermined range according to the operation amount of the acceleration device (17); and the travel mode determination means. When (13) is determined to be the second travel mode, if it is detected that the brake operation (19) has been performed, the retarder mode must be detected and the brake operation (19) must be detected. When the traveling mode selection means (13) for selecting the coasting mode and the traveling mode selection means (13) respectively select the retarder mode, the shift-up point and the shift-down point in the retarder mode are selected. Both are variably controlled to values higher than the shift-up point and the shift-down point in the first travel mode, and the travel mode selection means (13) When you select the mode comprises a downshift point in the coasting mode, and a second variable control means for variably controlling (13) the value in the vicinity of the downshift point in the first running mode, a.

  Here, the retarder ability is a technical term of braking ability (brake performance), and the retarder mode (also shown in FIGS. 2 and 4 described later) is a technical term of braking mode. Then, each corresponds to the technical term of increasing the effectiveness of the brake.

  In a preferred embodiment according to the first aspect of the present invention, the upshift point in the coasting mode is set to be higher than the upshift point in the first traveling mode.

  In the control method of the automatic transmission according to the second aspect of the present invention, the first traveling mode which is the traveling mode when the acceleration device (17) is operated, and the acceleration device (17) is not operated. A second travel mode that is a travel mode when the retarder mode is a travel mode when the second travel mode is intended to increase the retarder capacity, and the acceleration device (17) A coasting mode, which is a traveling mode when it is not operated or intended to be able to continue operation at a low engine speed when the operation amount of the acceleration device (17) is extremely small, When it is determined that the travel mode is the first travel mode in the step (S51) for determining whether the travel mode is the first travel mode or the second travel mode and the step (S51) for determining the travel mode. In addition, The step (S55) of variably controlling the shift-up point and the shift-down point in the first traveling mode within a predetermined range according to the operation amount of the acceleration device (17), and the traveling mode are determined. In step (S51), when it is determined that the second travel mode is selected, if the brake operation (19) is detected, the retarder mode must be detected and the brake operation (19) must be detected. For example, in the step of selecting the coasting mode (S53, S55) and the step of selecting the traveling mode (S53, S55), when the retarder mode is selected, the shift-up point in the retarder mode, and Both the downshift point are variably controlled to a value higher than the upshift point and the downshift point in the first traveling mode, and the traveling When the coasting mode is selected in the mode selection step (S53, S55), the step of variably controlling the shift down point in the coasting mode to a value in the vicinity of the shift down point in the first traveling mode (S55).

  According to the present invention, the shift point (shift down / up point) can be determined so that economical power running can be performed.

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

  FIG. 1 shows a system configuration of a control device for an automatic transmission according to an embodiment of the present invention.

  The automatic transmission control device 11 includes, for example, a transmission controller 13 and a transmission controller 13 for controlling a shifting operation of a hydraulically driven multi-stage automatic transmission (not shown) mounted on a vehicle such as a dump truck. And a transmission actuator 15 controlled by. The transmission actuator 15 is selectively connected to a plurality of clutches so as to switch speed stages (shift up and shift down) by selectively coupling and separating a plurality of hydraulic clutches in the hydraulic drive multi-stage automatic transmission. This is a switching valve for supplying hydraulic oil to the tank. The transmission controller 13 is, for example, a programmed computer, and drives and controls the transmission actuator 15 so that up-shifting and down-shifting are performed at an optimal timing according to a changing traveling state.

  The transmission controller 13 includes an accelerator pedal operation signal output from an accelerator pedal 17 operated by a driver, and a brake signal output from a hydraulic switch 19 that detects the operation of an oil-cooled multi-plate disc brake of the vehicle. The engine mode signal output from the mode changeover switch 21 operated by the driver, the transmission output shaft rotational speed signal output from the rotation sensor 23 provided on the output shaft of the multistage automatic transmission, and the driver A shift lever position signal output from the operated shift lever 25 is input.

  The accelerator pedal operation signal from the accelerator pedal 17 represents the operation amount (depression amount) of the accelerator pedal 17, or indirectly the opening of the throttle valve, or more generally, the degree of load on the vehicle. Therefore, instead of or in combination with the accelerator pedal operation signal, another signal indicating the throttle valve opening or the vehicle load level can be used. It can be seen from the accelerator pedal operation signal whether or not the accelerator pedal 17 is operated (depressed or released). In this specification, the state where the accelerator pedal 17 is depressed is referred to as “accelerator on”. In other words, the open state is called “accelerator off”. In addition, the accelerator pedal operation amount (throttle valve opening) is 100% (maximum depression amount) among the accelerator-on states is called “accelerator full”, and the accelerator pedal operation amount is less than 100% “accelerator partial”. That's it.

  The brake signal from the hydraulic switch 19 indicates whether or not the oil-cooled brake is operating (whether or not braking is being performed). In this embodiment, when the oil-cooled brake is operated, the service brake is operated by a driver's brake pedal operation, and the retarder brake is operated even when there is no brake pedal operation at a downhill or the like. There is a street. The brake signal indicates ON when at least one of the service brake and the retarder brake is operating, and the brake signal indicates OFF when neither the service brake nor the retarder brake is operated. The former state is referred to as “brake on” in this specification, and the latter state is referred to as “brake off”.

  The engine mode signal from the mode changeover switch 21 indicates which one the driver has selected as the travel mode for powering operation. Using the mode changeover switch 21, the driver can select a desired one from two types of a high power mode and an economy mode as a traveling mode for powering operation. Here, the high power mode is a traveling mode aimed at maximizing work efficiency by making the most of the power of the vehicle. On the other hand, the economy mode means that the shift-up point (the engine speed at which the shift-up is automatically performed) and the shift-down point (the shift-down is automatically performed) under light usage conditions such as when the vehicle is empty or flat. This is a travel mode aimed at improving the fuel consumption, noise, and shift shock by lowering the normal engine speed by making the engine speed) lower than the high power mode.

  The transmission output shaft rotational speed signal from the rotation sensor 23 represents the rotational speed of the output shaft of the multi-stage automatic transmission. In the control of the transmission controller 13, the rotation speed of the transmission output shaft is used instead of the engine rotation speed. For example, by applying the gear ratio of the speed stage selected at that time to the upshift point and downshift point determined as the engine speed value, the shift up converted to the value of the transmission output shaft speed Points and downshift points are obtained. By comparing the shift-up point and the shift-down point thus converted with the transmission output shaft rotational speed based on the signal from the rotation sensor 23, the engine rotational speed corresponding to the transmission output shaft rotational speed is obtained. Can be determined whether or not a predetermined shift-up point and shift-down point have been reached.

  The shift lever position signal from the shift lever 25 indicates where the driver is setting the shift lever. Depending on the shift lever position, the range of speed stages that can be selected by upshifting and downshifting varies. Since this is a conventional technique, a detailed description thereof will be omitted.

  The transmission controller 13 executes a travel mode determination 31, a shift point determination 33, and a shift timing control 35 based on the various signals described above. The driving mode determination 31 includes the accelerator on / off state grasped from the accelerator pedal operation signal, the brake on / off state grasped from the brake signal, and the mode selected by the driver grasped from the engine mode signal. This is a process of automatically selecting the travel mode based on the above. The shift point determination 33 is based on the selected travel mode and the accelerator pedal operation amount (depression amount) grasped from the accelerator pedal operation signal (that is, the throttle valve opening or the vehicle load level) and the shift down point and This control determines the shift-up point. The transmission timing control 35 is converted by applying the transmission output shaft rotational speed (or the transmission gear ratio thereto) determined from the determined shift down point and shift up point and the transmission output shaft rotational speed signal. Based on the engine speed (substantial engine speed)) and the shift lever position obtained from the shift lever position signal, it is determined whether it is time to shift up or down, If so, this is a process of giving an instruction signal to the transmission actuator 15 to execute upshifting or downshifting.

  Here, the travel modes that can be selected by the transmission controller 13 include the above two types of travel modes for powering operation that are the first travel mode of the present invention, that is, the high power mode and the economy mode. There are two types of travel modes for when the accelerator is off, that is, the second travel mode of the invention, that is, a retarder mode and a coasting mode. Both of the two types of driving modes for power running are selected only when the accelerator is on. Whether the high power mode or the economy mode is selected depends on the driver's mode selection by the mode changeover switch 21.

  On the other hand, when the accelerator is off, only two types of travel modes for when the accelerator is off, that is, the retarder mode and the coasting mode are selected. Here, the retarder mode means that both the downshift point and the upshift point are set higher than those during power running to keep the engine speed high, thereby ensuring a large amount of oil for the oil-cooled brake. This is a driving mode that aims to increase the ability. On the other hand, the coasting mode is a mode in which the driver operates the accelerator pedal when performing economical power running at a low engine speed by placing the shift down point in the vicinity of the minimum speed of the shift down point during power running. A driving mode aimed at allowing economical operation at low engine speeds to continue without downshifting even if the amount of pedaling is made very small or the accelerator pedal is released. It is. Whether the retarder mode or the coasting mode is selected depends on whether the brake is on or off. That is, the retarder mode is selected when the brake is on, and the retarder capability is improved. On the other hand, when the brake is off, the coasting mode is selected and economic operation is continued.

  Hereinafter, the travel mode determination 31 and the shift point determination 33 performed by the transmission controller 13 will be described in detail. If the shift point is determined, the shift timing control 35 can be performed by a known method, and thus detailed description of the shift timing control 35 is omitted.

  FIG. 2 is a flowchart showing a processing operation when the transmission controller 13 shown in FIG. 1 executes the traveling mode determination.

  In FIG. 2, the transmission controller 13 determines whether a brake signal is output from the hydraulic switch 19 (step S41), and whether an accelerator pedal operation signal (throttle valve opening signal) is output from the accelerator pedal 17 (step S41). Check S43). Furthermore, it is also checked what engine mode signal is output from the mode changeover switch 21 (step S45).

  As a result of the check in step S41, if a brake signal is output from the hydraulic switch 19 (that is, if the brake signal is on), regardless of the result of the check in step S43 (that is, the accelerator pedal operation signal) The transmission controller 13 sets the retarder mode regardless of whether the transmission is on or off. On the other hand, if the brake signal is turned off as a result of the check in step S41 and the accelerator pedal operation signal is output from the accelerator pedal 17 as a result of the check in step S43 (if the accelerator pedal operation signal is “ON”). The traveling mode is a traveling mode for powering operation, that is, either a high power mode or an economy mode. Therefore, based on the check result in step S45, the transmission controller 13 switches to the high power mode if the driving mode selected by the driver is the high power mode, and to the economy mode if the driving mode is the economy mode. The driving mode is set for each.

  If the result of the check in step S41 is that the brake signal is off and the result of the check in step S43 is that the accelerator pedal operation signal is off, the transmission controller 13 sets the traveling mode to the coasting mode. In this case, the engine mode signal is not output from the mode switch 21.

  The processing operation in the travel determination mode by the transmission controller 13 described above is repeatedly executed at a predetermined time interval.

  FIG. 3 is a flowchart showing a processing operation when the transmission controller 13 shown in FIG. 1 executes determination of shift points (shift-up point and shift-down point).

  In FIG. 3, the transmission controller 13 checks whether the determination result in the processing operation of the traveling mode determination shown in FIG. 2 is a high power mode, an economy mode, a retarder mode, or a coasting mode (step S51). . Further, based on the accelerator pedal operation signal output from the accelerator pedal 17, the magnitude of the amount of operation of the accelerator pedal 17 (the amount of depression of the accelerator 17) (throttle valve opening) is also checked (step S53). Next, a shift-down point and a shift-up point are determined based on the travel mode obtained in step S51 and the accelerator pedal operation amount obtained in step S53 (step S55).

  FIG. 4 is an explanatory diagram showing a method of determining a shift point by the transmission controller 13 shown in FIG. In FIG. 4, the engine speed (rpm) is set on the horizontal axis.

  In this embodiment, as shown in FIG. 4, the rated rotational speed of the engine that can obtain the maximum output (horsepower) is set to 2000 rpm.

  As shown in FIG. 4, the shift-up point when the travel mode is the retarder mode is 2450 rpm, which is a considerably higher rotational speed than the rated engine speed (2000 rpm) described above, and the shift-down point will be described later. The rotation speed is set to 1550 rpm, which is higher than that in the high power mode and economy mode.

  Next, when the travel mode is the high power mode (which is a travel mode for powering operation), the shift-up point is 2100 rpm, which is slightly higher than the rated rotational speed, which is considerably lower than the rated rotational speed. The rotation range is defined by 1750 rpm, and the shift down point is defined by 1400 rpm, which is considerably lower than the rated speed, and 1200 rpm, which is even lower than the rated speed. Each is set in the rotation area. That is, when the driving mode is the high power mode, when the amount of depression of the accelerator pedal 17 by the driver is the above-mentioned accelerator full, the shift-up point is 2100 rpm, the shift-down point is 1400 rpm, and the amount of depression of the accelerator pedal 17 However, in the case of the accelerator partial described above, the shift-up point is reduced to a minimum of 1750 rpm and the shift-down point is reduced to a minimum of 1200 rpm in accordance with the amount of depression of the accelerator pedal 17.

  Next, the shift-up point when the travel mode is the economy mode (which is a travel mode for powering operation) is 2000 rpm which is the same rotational speed as the rated rotational speed and a rotational speed which is considerably lower than the rated rotational speed. The shift-down point is in a rotation region defined by a certain 1750 rpm and a rotation region defined by 1300 rpm, which is considerably lower than the rated rotation speed, and 1200 rpm, which is lower than the rated rotation speed. , Respectively. That is, when the travel mode is the economy mode, when the amount of depression of the accelerator pedal 17 by the driver is the aforementioned accelerator full, the shift-up point is 2000 rpm, the shift-down point is 1300 rpm, and the depression amount of the accelerator pedal 17 is In the case of the accelerator partial described above, the shift-up point is reduced to a minimum of 1750 rpm and the shift-down point is decreased to a minimum of 1200 rpm in accordance with the amount of depression of the accelerator pedal 17.

  Further, when the running mode is the coasting mode, the shift-up point is a rotational speed considerably higher than the rated rotational speed (2000 rpm), which is the same rotational speed (2450 rpm) as that in the retarder mode. The down point is a rotational speed that is considerably lower than the rated rotational speed, and is set to the same rotational speed as 1200 rpm that is the lowest value of the downshift point in the traveling mode for powering operation.

  As is clear from the above description, in the high power mode, the engine is operated at a rotational speed region that is higher than the rated rotational speed of the engine as much as possible, and in the economy mode, the engine is operated at a rotational speed region that is lower than the rated rotational speed of the engine. It is designed to be driven.

  Further, even when the driving mode is set to the economy mode that is a driving mode for powering driving and the driver turns off the accelerator pedal 17 to release the accelerator pedal, the shift-up point and the shift-down point are reduced. Since all of the points are set to a lower rotational speed than the shift-up point and the shift-down point in the retarder mode, there is no automatic switching from the economy mode to the retarder mode, and the driver has low fuel consumption, Economic driving that can improve low noise and shift shock can be continued.

  In the retarder mode, the shift-up point and the shift-down point are higher than the shift-up point and the shift-down point in the running mode for power running (including both high power mode and economy mode), respectively. It is clear that it is set. In this way, in the retarder mode, the shift-up point and the shift-down point are set at a higher speed than the shift-up point and the shift-down point in the driving mode for powering operation, so that the retarder performance is the engine output. It is possible to operate the oil-cooled brake depending on the engine with high efficiency.

  FIG. 5 is an explanatory diagram showing the relationship between the accelerator operation amount (throttle opening) and the engine speed in the traveling mode for powering operation. FIG. 5 shows an example in the high power mode included in the traveling mode for powering operation.

  In FIG. 5, the accelerator operation amount (throttle opening) is set on the horizontal axis, and the engine speed is set on the vertical axis. Reference numeral 61 indicates switching of the upshift point, and reference numeral 63 indicates switching of the downshift point.

  As indicated by reference numeral 61, the shift-up point is switched stepwise from 1750 rpm to 2100 rpm in accordance with a change in the operation amount (depression amount) of the accelerator pedal 17 by the driver. On the other hand, as indicated by reference numeral 63, the downshift point is also switched in stages from 1200 rpm to 1400 rpm in accordance with the change in the operation amount (depression amount) of the accelerator pedal 17 by the driver.

  FIG. 6 is an explanatory diagram showing fuel consumption-vehicle speed characteristics in a traveling mode for powering operation.

  In FIG. 6, the vehicle speed (km / h) is set on the horizontal axis, and the fuel consumption (L / h) is set on the vertical axis. In FIG. 6, the solid line represents the relationship between the vehicle speed and fuel consumption when the shift-up point is (engine speed) 1750 rpm, and the broken line represents the relationship between the vehicle speed and fuel consumption when the shift-up point is (engine speed) 2100 rpm. Each one is shown. Comparing and comparing the fuel consumption-vehicle speed characteristics indicated by the solid line with the fuel consumption-vehicle speed characteristics indicated by the broken line, the fuel consumption-vehicle speed characteristic indicated by the solid line is lower than the fuel consumption-vehicle speed characteristic indicated by the broken line. It is clear that the mileage is improved as a whole and the fuel efficiency is good as a whole.

  As mentioned above, although embodiment of this invention was described, this embodiment is only the illustration for description of this invention, and is not the meaning which limits the scope of the present invention only to this embodiment. The present invention can be implemented in various other modes without departing from the gist thereof.

1 is a block diagram showing a system configuration of an automatic transmission control device according to an embodiment of the present invention. The flowchart which shows the processing operation at the time of the transmission controller of FIG. 1 performing driving | running | working mode determination. 2 is a flowchart showing a processing operation when the transmission controller shown in FIG. 1 determines shift points (shift-up point and shift-down point). Explanatory drawing which shows the method of the shift point determination by the transmission controller of FIG. Explanatory drawing which shows the relationship between the amount of accelerator operation (throttle opening) and engine speed in the driving mode for power running. Explanatory drawing which shows the fuel consumption-vehicle speed characteristic in the running mode for power running.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Automatic transmission control apparatus 13 Transmission controller 15 Transmission actuator 17 Accelerator pedal 19 Hydraulic switch 21 Mode switch 23 Rotation sensor 25 Shift lever 31 Travel mode determination 33 Shift point determination 35 Shift timing control

Claims (3)

A first travel mode which is a travel mode when the acceleration device (17) is operated;
A second travel mode which is a travel mode when the acceleration device (17) is not operated;
Have
The second traveling mode is
Retarder mode that is a running mode when intending to increase the retarder capacity,
This is a travel mode when the accelerator (17) is not operated or the operation amount of the accelerator (17) is extremely small, and it is intended to be able to continue operation at a low engine speed. Coasting mode,
Including
Traveling mode discriminating means (13) for discriminating whether the traveling mode is the first or second traveling mode;
When the travel mode determination means (13) determines that the travel mode is the first travel mode, the amount of operation of the acceleration device (17) is determined based on the shift-up point and the shift-down point in the first travel mode. First variable control means (13) variably controlled within a predetermined range according to
When the travel mode discriminating means (13) determines that the second travel mode is selected, it detects that the brake operation (19) has been performed, and enters the retarder mode, and the brake operation (19) has been performed. If the vehicle is not detected, the coasting mode is selected, respectively, traveling mode selection means (13),
When the travel mode selection means (13) selects the retarder mode, both the upshift point and the downshift point in the retarder mode are used as the upshift point and the downshift in the first travel mode. When the traveling mode selection means (13) selects the coasting mode, the shift down point in the coasting mode is changed to the shift down point in the first traveling mode. Second variable control means (13) for variably controlling to a value in the vicinity of
An automatic transmission control device comprising: The control apparatus for an automatic transmission according to claim 1, wherein a shift-up point in the coasting mode is set in a region higher than a shift-up point in the first traveling mode. A first travel mode which is a travel mode when the acceleration device (17) is operated;
A second travel mode which is a travel mode when the acceleration device (17) is not operated;
Have
The second traveling mode is
Retarder mode that is a running mode when intending to increase the retarder capacity,
This is a travel mode when the accelerator (17) is not operated or the operation amount of the accelerator (17) is extremely small, and it is intended to allow operation at a low engine speed to be continued. Coasting mode,
Including
Determining whether the travel mode is the first or second travel mode (S51);
In the step of determining the travel mode (S51), when it is determined that the travel mode is the first travel mode, the shift-up point and the shift-down point in the first travel mode are determined by the acceleration device (17). A step of variably controlling within a predetermined range according to the operation amount (S55),
In the step of determining the travel mode (S51), when it is determined that the second travel mode is selected, when the brake operation (19) is detected, the retarder mode is switched to the brake operation (19). If it is not detected that the coasting mode is selected (S53, S55),
In the step of selecting the travel mode (S53, S55), when the retarder mode is selected, both the shift-up point and the shift-down point in the retarder mode are set as the shift-up point in the first travel mode. When the coasting mode is selected in the step of selecting the running mode (S53, S55), the shift down point in the coasting mode is set to the first mode. Variably controlling to a value in the vicinity of the downshift point in the driving mode (S55);
An automatic transmission control method comprising:

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