JP2008106841A - Speed-change controller for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent complete release of a lock-up clutch of a torque converter during a speed-change action following rotation synchronization control during shifting of an automatic transmission, and requirement of time until re-engagement of the lock-up clutch from speed-change action completion. <P>SOLUTION: In the speed-change controller, when there is a speed-change action following the rotation synchronization control during shifting (YES in S1-S4), a lock-up clutch engagement pressure of the torque converter 3 is retained in a standby pressure being an oil pressure in a stroked state of a lock-up piston of the lock-up clutch, and in a substantially zero state of a lock-up capacity (S5). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine that is a prime mover, a stepped transmission mechanism of a vehicle that includes a plurality of friction elements that cut off or connect a driving force input from the engine, and a lock that is inserted between the prime mover and the stepped transmission mechanism. The present invention relates to a control device for suitably realizing a shift operation in a power train of a vehicle including a torque converter with an up clutch (friction element) when the friction element is released and fastened to perform a shift operation.

As a shift control device for an automatic transmission that automatically shifts the above-mentioned stepped transmission mechanism, the applicant of the present application has already proposed a shift control device as described in Patent Document 1.
This shift control device for an automatic transmission performs rotation synchronization control during shifting (during shifting operation). Outlined about the rotation synchronization control, at the time of a shift operation, the engine rotation speed Ne and the input rotation speed Nt of the automatic transmission are calculated from the next selected shift speed, etc., and the engine torque is increased. Then, engine control is performed so that the engine speed Ne becomes the synchronous speed. Then, in synchronization with the timing at which the engine speed Ne and the input speed Nt coincide with the synchronous speed, the friction element (such as a clutch) related to the currently selected shift speed changes to the friction element related to the next selected shift speed. Perform the changing operation. In the shifting operation to be downshifted, in the process of the changeover operation, a neutral state in which both the friction element related to the currently selected shift stage and the friction element related to the next selected shift stage are released is assumed. Become.

By the way, the torque converter with a lock-up clutch is widely used at present because it can enjoy the torque increasing function and the vibration absorbing function which are the advantages of the torque converter and avoid the torque loss which is the disadvantage of the torque converter. .
When the lockup clutch is slipped during the shifting operation, the difference between the turbine runner rotation speed of the torque converter equal to the input rotation speed Nt of the automatic transmission and the pump impeller rotation speed equal to the engine rotation speed Ne is a predetermined state. As described above, Patent Document 2 discloses a technique relating to a slip control device for a lock-up clutch that feedback-controls the oil pressure of the lock-up clutch. According to the slip control of the lockup clutch, at the end of the shift operation, it is possible to shorten the time until the lockup clutch is engaged, and to prevent a shock when the friction element relating to the next selected shift stage is completely engaged. be able to.
JP 2006-57691 A JP-A-5-106729

  However, when the downshift, which is a shift operation that shifts the gear ratio to the low gear side, is performed while the vehicle is running on the coast with the lockup clutch fully engaged, the rotation synchronization control in the automatic transmission described above and the slip control in the torque converter are performed. If these are executed in a simple combination, the following problems occur.

  That is, since the automatic transmission is once in the neutral state, the turbine runner of the torque converter (the input shaft of the automatic transmission) is disconnected from the output shaft of the automatic transmission. Then, regardless of the engagement pressure state of the lockup clutch, the pump impeller rotation speed of the torque converter and the turbine runner rotation speed become equal, and it becomes difficult to accurately execute the slip control of the lockup clutch. In this case, the slip control device advances the hydraulic control to the release side of the lockup clutch by feedback control so that the difference between the turbine runner rotation speed and the pump impeller rotation speed is in a predetermined state. However, no matter how much the oil pressure is controlled to the disengagement side, no differential rotation occurs, and finally the lockup clutch is completely disengaged and the lockup piston does not stroke at all.

As a result, when the shift operation is completed and the lockup clutch is engaged again, the hydraulic pressure must be controlled from the fully released state to the engagement side, and the time until the lockup clutch is engaged is completed. Such a problem arises. If it does so, driving | running | working fuel consumption will deteriorate, durability will be impaired, for example, a lockup clutch will be worn out.
Alternatively, if the lockup clutch hydraulic pressure is suddenly raised after the shift operation is completed to complete the above-mentioned problem of taking a long time, a shock is generated, and the ride comfort performance deteriorates this time.

  It is an object of the present invention to improve the problem that it takes time to complete the engagement of the lock-up clutch described above when executing the rotation synchronous control during shift of the automatic transmission.

For this purpose, a shift control device for an automatic transmission according to the present invention is as described in claim 1.
An automatic transmission to which engine rotation is input via a torque converter with a lockup clutch that is engaged by being pressed by a lockup piston, and a selected shift stage of the automatic transmission is changed according to the driving state of the vehicle Shift control means for instructing a shift operation to perform, and lockup clutch control means for controlling the fastening pressure of the lockup clutch,
During a speed change operation, the speed change control means calculates a synchronous speed of the engine speed and the input speed of the automatic transmission, and releases the speed change friction element that transmits power at the currently selected speed. In this case, the shift-time rotation synchronization control is performed in such a manner that the shift friction element for transmitting power at the next selected shift speed is engaged in synchronization with the timing at which the engine speed and the input speed coincide with the synchronous speed. In a shift control device for an automatic transmission that executes
When the shift control means performs a shift operation in which the shift-time rotation synchronization control is performed, the lock-up control means uses the engagement pressure of the lock-up clutch, the lock-up piston is in a stroke state, and locks up. It is characterized in that the capacity is maintained at a standby pressure that is a hydraulic pressure in a substantially zero state.

  According to the speed change control device of the present invention, the lockup clutch engagement pressure is not controlled by feedback control, the lockup piston is in a stroke state by feedforward control, and the clutch capacity of the lockup clutch is zero or substantially reduced. Since the standby pressure is zero, the lockup clutch never reaches the fully released state. Therefore, when the shift operation is completed and the lockup clutch is engaged again, the lockup clutch can be quickly brought into the engagement completion state. As a result, traveling fuel consumption and durability of the lockup clutch can be improved.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a vehicle equipped with a shift control device for an automatic transmission according to an embodiment of the present invention, together with its control system. Reference numeral 1 denotes an engine, and 2 denotes an automatic transmission. The power train is configured.
The engine 1 controls the throttle valve opening independently of the driver's accelerator pedal operation, so that the output (number of revolutions and torque) is adjusted. The engine output is input to the automatic transmission 2 via the torque converter 3. Shall be.

The opening degree of the throttle valve (not shown) of the engine 1 is determined mainly by the depression amount of an accelerator pedal (not shown), and the opening degree is controlled by a throttle actuator. In the shift operation of the automatic transmission 2, the engine torque is adjusted for the purpose of controlling the shift operation, and rotation-time rotation synchronization control is performed as described later.
The engine controller 4 controls the throttle valve opening of the engine 1.

The engine controller 4 performs normal engine control such as fuel injection amount control. For this reason, the engine controller 4 includes a signal from an accelerator opening sensor (not shown) that detects an accelerator opening of an accelerator pedal (not shown). A signal from an engine rotation sensor (not shown) that is provided in the engine 1 and detects the engine rotation speed is input, and normally a normal target engine rotation speed corresponding to the vehicle operating state such as the accelerator opening and the engine rotation speed is set. The engine output control including the fuel injection amount control and the ignition timing control is performed so that this is achieved.
The engine controller 4 issues a fuel cut to make the fuel injection amount zero by issuing a fuel cut command to a fuel injection device (not shown) of the engine 1 when the driver releases the accelerator pedal and the accelerator opening is zero. Do. Therefore, the fuel supply to the engine is stopped during coasting (inertia) where the accelerator opening is 0, which contributes to improvement in traveling fuel consumption.

The automatic transmission 2 is a linear motion that directly controls the hydraulic fluid pressure to be supplied to a frictional element for shifting such as a hydraulically operated clutch or a hydraulically operated brake that determines a power transmission path (shift stage) of the gear transmission system. For this reason, hydraulic fluid duty solenoids are inserted into a control valve (not shown) for speed change control provided in the automatic transmission 2 by the number of the friction elements for speed change.
These hydraulic fluid duty solenoids individually control the hydraulic fluid pressure of the corresponding friction elements, and selectively engage the friction elements to bring the automatic transmission 2 into a state where a predetermined gear stage is selected. To get.
The automatic transmission 2 shifts and outputs the engine power at a gear ratio corresponding to the selected shift speed.

  In addition to inputting the accelerator opening degree and the engine speed Ne of the engine 1 to the transmission controller 5 via the engine controller 4, the input speed inputted to the automatic transmission 2 from the turbine runner of the torque converter 3. A signal from an input rotation sensor (not shown) that detects Nt, a signal from an output rotation sensor (not shown) that detects the output speed (corresponding to the vehicle speed) of the automatic transmission 2, and a throttle opening signal from the engine controller 4 input.

The transmission controller 5 executes a known control program (not shown) based on the input information described above, and controls the automatic transmission 2 to change the speed as follows.
First, a gear stage suitable for the current operating state is obtained from a vehicle speed and an accelerator opening obtained by calculation from the transmission output rotation speed, based on a planned shift pattern (not shown).
If the preferred shift speed matches the currently selected shift speed, the shift duty is not issued as the speed change is not performed, so that the drive duty of the duty solenoid is kept as it is, and the current selected speed shift is maintained. Keep the stage.
However, if the currently selected shift stage is different from the preferred shift stage, a shift command is issued to change the corresponding duty solenoid drive duty so that the shift from the selected shift stage to the preferred shift stage is performed. Performs exchange by releasing and fastening elements.

When the transmission controller 5 issues a shift command, the automatic transmission 2 performs a shift operation.
During the shift operation, the rotation-time rotation synchronization control described in Patent Document 1 is performed. That is, a synchronous rotational speed between the engine rotational speed Ne of the engine 1 and the input rotational speed Nt of the automatic transmission 2 (= turbine runner rotational speed of the torque converter 3) is calculated from a preferred gear stage to be selected next, and the engine controller 4 issues a command to the engine 1 so that the engine torque is increased by cooperative control and the engine speed Ne becomes the synchronous speed. Then, in synchronization with the timing at which the engine speed Ne and the input speed Nt coincide with the synchronous speed, the friction related to the next preferred gear to be selected from the friction element (such as a clutch) related to the currently selected speed. Perform a change operation to the element. In the shifting operation for downshifting, in the process of changing the friction element for shifting, the neutral element that releases both the friction element related to the currently selected shift stage and the friction element related to the next selected shift stage. It will go through a state.

  Although the torque converter 3 has a well-known configuration and is not illustrated in detail, a pump impeller as a torque converter input element coupled to the crankshaft of the engine 1 and driven by the engine, and an input shaft of the continuously variable transmission 2 And a turbine runner as a torque converter output element coupled to the pump impeller, and a lockup type torque converter including a lockup clutch that directly connects between the pump impeller and the turbine runner.

  The lock-up clutch is also a well-known configuration, and the engagement force of the lock-up clutch is determined by the differential pressure between the apply pressure and the release pressure before and after that (lock-up clutch engagement pressure). If the apply pressure is lower than the release pressure, the lock-up clutch is locked. The up clutch is completely released and does not connect between the pump impeller and the turbine runner, and the torque converter 3 functions in a converter state in which the slip is not limited.

When the apply pressure is higher than the release pressure, the lockup clutch is engaged with a force corresponding to the differential pressure, and the torque converter 3 is the sum of the lockup capacity (torque) according to the engagement force of the lockup clutch and the converter torque. It functions in the slip control state that outputs the torque represented by the value.
When the differential pressure becomes larger than the set value, the lockup clutch is completely engaged and the relative rotation between the pump impeller and the turbine runner is eliminated, and the torque converter 3 is caused to function in the lockup state.
During this lockup state, the output torque (turbine torque) of the torque converter 3 is determined only by the lockup capacity (torque) corresponding to the fastening force of the lockup clutch.

  The apply pressure and the release pressure are determined by a control valve provided in the automatic transmission 2 in FIG. 1, and the transmission controller 5 issues a command regarding the above-described differential pressure (lockup clutch engagement pressure) to the control valve. .

  Here, the negative value of the lock-up clutch engagement pressure means that the torque converter 3 is brought into the converter state. Conversely, when the lock-up clutch engagement pressure is positive, the engagement force of the lock-up clutch increases as the value increases. (Lock-up capacity) is increased, which means that the slip rotation of the torque converter 3 is largely limited, and finally the torque converter 3 is brought into a lock-up state.

The transmission controller 5 first determines whether the operation is performed in the lock-up region or the converter region from the output information corresponding to the throttle opening and the vehicle speed in the input information, and the lock is performed according to these determination results. The torque converter 3 is brought into a lock-up state or a converter state by engaging or releasing the up clutch.
On the other hand, the transmission controller 5 performs slip control of the lock-up clutch so that the torque converter 3 rotates at a predetermined differential rotation as appropriate according to the driving state.

  This slip control may be a well-known one, and is a control for setting the differential rotation between the pump impeller and the turbine runner to a predetermined value that is not too high or too low and that is appropriate for experience and design. Specifically, the transmission controller 5 calculates a differential rotation (Ne−Nt) based on the engine rotation speed Ne corresponding to the pump impeller rotation speed and the input rotation speed Nt corresponding to the turbine runner rotation speed. The lockup clutch engagement pressure is feedback-controlled so that the deviation between the rotation (Ne−Nt) and the predetermined value is small.

As described above, in this embodiment, when the rotation synchronization control of the engine 1 and the automatic transmission 2 is not executed during the speed change operation, the slip control of the torque converter 3 is executed according to the running condition. It should be noted that the rotation synchronization control of the engine 1 and the automatic transmission 2 is executed during a downshift operation during coasting. Further, if the vehicle is running on the coast, the fuel cut of the engine 1 is also executed.
In this embodiment, when the rotation synchronization control, slip control, and fuel cut are simply combined and executed, there is a problem that it takes time from the completion of the shift operation to the completion of the lock-up clutch engagement. In order to solve this problem, the cooperative control described below is executed.
FIG. 2 is a flowchart showing the cooperative control in this embodiment. This cooperative control is executed by the transmission controller 5 and the engine controller 4 when the automatic transmission 2 performs a downshift operation such as shifting from the third speed to the second speed.
First, in step S1, it is monitored whether or not there is a shift command for downshifting. If there is no shift command for downshift (NO), this flowchart is exited. On the other hand, if there is a shift command for downshifting (YES), the process proceeds to the next step S2.

  In step S2, it is determined whether or not there is a command to enter the lockup state or the slip state immediately before the start of the shift operation, and whether to instruct the lockup state or the slip state immediately after the completion of the shift operation. This determination is made based on whether or not the current vehicle speed and throttle opening are in the lock-up control region or the slip control region previously defined by the vehicle speed and throttle opening. And when there is no command from the lock-up state to the lock-up state before and after such a shift operation (NO), this flowchart is exited. On the other hand, if there is a command from the lock-up state or the slip state to the slip state before and after the shift operation (YES), the process proceeds to the next step S3.

  In step S3, it is determined whether or not there is a slip control command during the shifting operation. This determination is made based on whether or not the current vehicle speed and the throttle opening are within a shift controllable region during shifting that is defined in advance by the vehicle speed and the throttle opening. If there is no slip control command (NO), this flowchart is exited. On the other hand, if there is a command for slip control (YES), the process proceeds to the next step S4.

In step S4, it is determined whether or not to execute rotation synchronization control. If it is determined not to execute (NO), a differential speed (Ne−Nt) is calculated based on the engine speed Ne and the input speed Nt corresponding to the turbine runner speed in step S10, and this differential speed (Ne− The slip control is performed by feedback control of the lockup clutch engagement pressure so that the deviation between Nt) and the predetermined value becomes small. In the next step S11, it is determined whether or not the change of the effective gear ratio is completed. If the change in the effective gear ratio continues (NO), the process returns to step S10 and the slip control in S10 is continued until the change in the effective gear ratio Gr is completed. When the change of the effective gear ratio is completed (YES), the process proceeds to step S7.
On the other hand, if it is determined to execute in step S4 (YES), the process proceeds to the next step S5.

In step S5, without performing the slip control by the feedback control determined in step S3, that is, the slip control is prohibited, and a hydraulic pressure command is issued so that the lockup clutch engagement pressure becomes the standby pressure by the feedforward control. Specifically, a step-like hydraulic command is issued to the standby pressure as the shifting operation starts. Note that the standby pressure refers to a lock-up fastening pressure at which the stroke of the lock-up piston is completed and the lock-up capacity is substantially 0 or slightly positive. In other words, the standby pressure is a hydraulic pressure that is prepared (standby) so that it can be immediately and completely engaged. The standby pressure may be a value obtained in advance by calculation, or may be a value calculated by well-known lock-up learning control or the like.
As a result, it is possible to prevent a shock from occurring when the shift operation is completed and the lockup clutch is completely engaged, and the lockup clutch can be fully engaged immediately after the shift operation is completed.

In the next step S6, the effective gear ratio Gr is monitored, and it is determined whether or not the change of the effective gear ratio Gr is completed. The effective gear ratio Gr is obtained by dividing the output rotational speed by the input rotational speed Nt. This determination is made based on whether or not the value Grref that is a criterion for determining the end of the shifting operation has been reached. If the change in the effective gear ratio Gr is continuing (NO), the process returns to step S5, and a command is issued to continue the lockup clutch engagement pressure to the standby pressure. Thus, the lockup clutch engagement pressure is held at the standby pressure during the shifting operation.
On the other hand, when the change of the effective gear ratio Gr is completed (YES), the process proceeds to step S7.

In step S7, it is determined whether a fuel cut command is issued during coasting. If it is not coast running, this flowchart may be omitted.
Even during coasting, if the fuel cut command has not been issued (NO), the process returns to step S5 and a command is issued to continue the lockup clutch engagement pressure to the standby pressure. Thus, the lockup clutch engagement pressure is maintained at the standby pressure until the fuel cut of the engine 1 is started (at the time of cut-in).
On the other hand, if the fuel cut command has already been issued (YES), the process proceeds to step S8.

  In step S8, the lockup clutch is completely engaged by a kind of slip control which is smooth-on control described later after the start of fuel cut. When completely engaged, the lock-up state immediately after completion of the speed change operation determined as YES in step S2 is achieved, and the process exits this flowchart.

The cooperative control operation according to the above embodiment will be described with reference to the time chart shown in FIG. This time chart is a time chart when there is a command to enter the lockup state immediately before the start of the shift operation and a command to enter the lockup state immediately after the completion of the shift operation. For comparison, the behavior when the slip control is performed at the time of downshift without performing the rotation synchronization control is indicated by a broken line.
In FIG. 3, there is a command to make the lock-up state before the instant t1, the lock-up clutch engagement pressure is large, and the lock-up clutch is brought into the lock-up state. The engine torque Te is a negative value.

  A shift command for downshifting is issued at the instant t1 (YES in step S1), and the shift operation is started. In response to this, the control state of the lockup clutch shifts to the slip control state (YES in step S3). Then, a standby pressure command is issued to the control valve in a step-like manner from the hydraulic pressure command value at the time of shifting determination so that the lockup clutch engagement pressure is immediately lowered to the standby pressure simultaneously with the start of the shifting operation (step S5).

  By the way, even if the shift command of the transmission controller 5 is accurate in time, the actual shift operation of the automatic transmission 2 that operates by hydraulic pressure varies, so that for example 0.5 seconds from instant t1 to instant t5 There is a concern that the lock-up clutch engagement pressure cannot be set to the standby pressure in time during the slight shifting operation. Therefore, by issuing the command simultaneously with the start of the speed change operation in this manner, the lockup clutch engagement pressure can be reliably set to the standby pressure at the end of the speed change operation. In this embodiment, a step-like oil pressure command up to the standby pressure is issued at the start of the shifting operation. However, there is a possibility that an undershoot of the oil pressure may occur. May be.

  At the subsequent instant t2, based on the rotation synchronization control (step S4), the engine controller 4 issues an instruction to increase the engine torque Te to adjust the engine rotation speed to the synchronization rotation speed. During the rotation synchronization control, fuel cut is not performed, and even if the fuel cut execution condition is satisfied, the execution is temporarily stopped and fuel is supplied.

  After that, when the effective gear ratio Gr reaches a value Grref that is a determination criterion for the end of the shifting operation at the instant t5 (YES in step S6), it is determined that the change of the effective gear ratio Gr has ended. A command is then issued to reduce the engine torque Te to 0 with a ramp gradient.

  At the following instant t6, the engine torque Te command is issued in steps from 0 to a negative value, and the fuel supply stop (fuel cut) is resumed at the instant t6a, and the engine torque is restored to the coast torque before the instant t1. After the instant t6, the engine speed decreases, and at the subsequent instant t7, the engine speed Ne becomes a minimum value and starts increasing after the instant t7.

  At the subsequent instant t7, the control state of the lockup clutch shifts to smooth on control. Smooth-on control refers to slip control in which the lock-up clutch engagement pressure is increased by two-stage open roof control in order to enter the lock-up state. Therefore, this is not slip control for feedback control of differential rotation (Ne−Nt). First, from the instant t7 to the following instant t9, a command to increase the lockup clutch engagement pressure with a ramp gradient is issued. The instant t9 is the time when the engine speed Ne reaches a value Nref2 that is a criterion for the smooth-on control determination. Note that the shifting operation that is downshifted at the instant t8 between the instant t7 and the instant t9 is completed.

  From the instant t9 to the subsequent instant t10, a command is issued to increase the lockup clutch engagement pressure with a ramp ramp that is gentler than the ramp gradient described above from the instant t7 to the subsequent instant t9. At the instant t10, the lockup clutch engagement pressure returns to the value before the instant t1 and enters the lockup state.

By the way, according to the above-described embodiment, the automatic transmission 2 to which the engine rotation is inputted via the torque converter 3 with the lock-up clutch that is engaged by being pressed by the lock-up piston, and the driving state of the vehicle A transmission controller 5 which is a shift control means for instructing a shift operation for changing the selected gear position of the automatic transmission 2 according to the transmission, and a transmission which is also a lockup clutch control means for controlling the engagement pressure of the lockup clutch The controller 5 includes a controller 5, and at the time of a shifting operation, the transmission controller 5 calculates a synchronous rotational speed between the engine rotational speed Ne and the input rotational speed Nt of the automatic transmission, and transmits power at the currently selected shift speed. The speed change friction element to be released is brought into a neutral state, and the speed change friction element for transmitting power at the next selected shift speed is set to the engine speed. In a shift control device for an automatic transmission that executes rotation-time rotation synchronization control that is engaged in synchronism with the timing at which the input rotation speed matches the synchronization rotation speed, the transmission controller 5 executes the shift-time rotation synchronization control. During the speed change operation, the transmission controller 5 is configured to maintain the lockup clutch engagement pressure at the standby pressure.
For this reason, it is possible to realize improvement in travel fuel consumption and prevention of wear of the lock-up clutch without taking time until the lock-up clutch is completely engaged after the shift operation is completed as in the prior art.

  Further, simultaneously with the start of the shift operation to be downshifted (YES in step S1), a step-like hydraulic pressure command for setting the lock-up clutch engagement pressure to the standby pressure is issued (step S5). In addition, it is possible to quickly realize wear prevention of the lockup clutch.

  Further, when the vehicle includes a fuel cut means for stopping the fuel supply to the engine 1 during the coasting, during the shift operation that causes a downshift during the coasting, When the fuel supply stop by the fuel cut means is temporarily stopped after the instant t2, and the fuel supply stop is resumed after the subsequent instant t6a, the lockup clutch is completely engaged at the instant t10 thereafter. As a result, the shift rotation synchronous control that requires control for increasing the engine torque Te as shown in FIG. 3 is realized. Subsequent to the start of fuel cut in step S8, the transmission controller 5 fully engages the lockup clutch. Thereby, in the case of changing from the lock-up state before and after the shift operation to the lock-up state, it is possible to reduce the occurrence of shock at the time of cut-in.

  When the lockup clutch is completely engaged, as shown in FIG. 3, after the fuel supply stop is resumed, the lockup clutch engagement pressure is increased from the standby pressure to the instant t10 with a predetermined ramp gradient from the instant t7. Take control. Therefore, when the differential rotation of the torque converter 3 is large, the ramp gradient is set to be large, so that the lockup clutch engagement pressure can be increased more quickly than in the normal slip control in which feedback control is performed. Since the ramp gradient is set small when the differential rotation of the torque converter 3 is small, it is possible to alleviate the shock when the lockup clutch is engaged.

  The above description is only an example of the present invention. The present invention can be variously modified without departing from the gist of the present invention. For example, the present invention may be applied to an upshift.

1 is a system diagram showing a power train of a vehicle including a shift control device for an automatic transmission according to an embodiment of the present invention, together with its control system. It is a flowchart showing the slip control in the speed change operation | movement of the Example. It is a time chart showing the speed change operation | movement of the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Torque converter 4 Engine controller 5 Transmission controller

Claims (4)

An automatic transmission to which engine rotation is input via a torque converter with a lockup clutch that is engaged by being pressed by a lockup piston, and a selected shift stage of the automatic transmission is changed according to the driving state of the vehicle Shift control means for instructing a shift operation to perform, and lockup clutch control means for controlling the fastening pressure of the lockup clutch,
During a speed change operation, the speed change control means calculates a synchronous speed of the engine speed and the input speed of the automatic transmission, and releases the speed change friction element that transmits power at the currently selected speed. The shift rotation synchronous control is performed in such a manner that the shift friction element for transmitting power at the next selected shift speed is engaged in synchronization with the timing at which the engine speed and the input speed coincide with the synchronous speed. In a shift control device for an automatic transmission that executes
When the shift control means performs a shift operation for executing the rotation-time rotation synchronization control, the lock-up control means uses the engagement pressure of the lock-up clutch, the lock-up piston is in a stroke state, and locks up. A shift control device for an automatic transmission, wherein the shift control device is configured to maintain a standby pressure that is a hydraulic pressure in a substantially zero state. The shift control apparatus for an automatic transmission according to claim 1,
The lockup clutch control means issues a command to set the engagement pressure of the lockup clutch to a standby pressure simultaneously with the start of a downshift transmission operation in which the shift control means executes the rotation-time rotation synchronization control. A shift control device for an automatic transmission. The shift control device for an automatic transmission according to claim 1 or 2, further comprising fuel cut means for stopping fuel supply to the engine during coasting.
When the shift control means performs a shift operation during coasting in which the rotation-time rotation synchronization control is performed, the fuel supply stop by the fuel cut means is temporarily stopped,
The shift control device for an automatic transmission, wherein the lockup clutch control means completely engages the lockup clutch after the fuel supply stop is resumed. The shift control apparatus for an automatic transmission according to claim 3,
The lockup clutch control means issues a command to increase the engagement pressure of the lockup clutch from the standby pressure with a predetermined ramp gradient toward the complete engagement after restarting the fuel supply stop. Shift control device for automatic transmission.

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