JP2005337410A - Method of variably controlling speed of automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a transmission from producing shock and an engine from blowing revolution up by applying engagement hydraulic pressure at proper timing even if a rising speed of input rotational frequency is different from when power-on down shift (performing down shift when throttle opening is opened at certain degree) is performed. <P>SOLUTION: This method comprises step of asking for time rate of change of turbine rotational frequency in the middle time of variable speed when down shift is performed in power-on condition and step of presuming time until a turbine reaches rotational frequency at low-speed stage from the turbine rotational frequency and its time rate of change. The method also comprises step of determining output timing of the engagement hydraulic pressure so that the presumed time and response time of engagement hydraulic pressure of engagement side engaging element approximate and step of outputting the engagement hydraulic pressure on the engagement side engaging element in this timing. Therefore, the method is capable of raising hydraulic pressure of the engagement side engaging element as high as hydraulic pressure of engagement completion condition immediately when the turbine rotational frequency reaches rotational frequency at low-speed stage and can improve shock. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a shift control method for an automatic transmission, and more particularly to a shift control method during a power-on downshift.

In general, an automatic transmission automatically determines a gear position from a shift map according to driving conditions such as a vehicle speed and a throttle opening, and shifts by supplying or discharging hydraulic pressure to an engagement element. In such an automatic transmission, for example, when the accelerator pedal is depressed while traveling at the third speed, the operating point determined by the vehicle speed and the throttle opening at that time crosses the 3-2 downshift line of the shift map. A so-called power-on downshift, in which the gear is shifted to the second speed, is performed.
Here, the power-on downshift is to perform a downshift with the throttle opening (accelerator opening) being opened to some extent. The downshift as described above is realized by engaging one engaging element and releasing another engaging element.

FIG. 9 shows changes over time in the turbine speed, the command current and hydraulic pressure of the engagement side engagement element, and the command current and hydraulic pressure of the release side engagement element in the power-on downshift from the third speed to the second speed. The command current refers to a current supplied to an electromagnetic proportional control valve for controlling the supply hydraulic pressure of the engagement element.
When a power-on downshift gear shift command is issued at time t1, the engagement-side engagement element is loosened until time t2, and then a standby pressure is output to the engagement-side engagement element at time t2. Here, the standby pressure is a hydraulic pressure that is waiting in a state before starting engagement so as not to affect the feedback control of the disengagement side engagement element. Here, the standby pressure is changed stepwise, but it may be a constant pressure. On the other hand, if the hydraulic pressure of the disengagement side engagement element is reduced to the initial pressure at time t2, and it is detected at time t3 that the turbine rotation speed has increased by a constant value n1 from the rotation speed at the third speed (out of synchronization detection) The hydraulic pressure of the disengagement side engagement element is feedback controlled so that the turbine rotation speed becomes the target change rate. Then, if it is detected (synchronized prediction) that the pressure has increased to a value lower than the turbine speed at the second speed by a predetermined value n2 at time t4, the hydraulic pressure of the engagement side engagement element is increased stepwise from the standby pressure. After that, the engagement control for increasing at a predetermined gradient is performed, and at the time when the turbine rotation speed reaches the rotation speed at the second speed (time t5), the feedback control of the disengagement side engagement element is finished and at the same time Engagement element end processing is performed to enter the second speed state.

FIG. 9 shows an ideal power-on downshift, and the time (t4 to t5) from when the turbine rotation speed reaches the rotation speed at the second speed from the synchronization prediction is the hydraulic response time Tr of the engagement side engagement element. Is almost equal and no shock occurs. Here, the hydraulic response time Tr refers to the time during which the engagement hydraulic pressure rises to the hydraulic pressure at the completion of engagement after the command signal is output to the solenoid valve.
However, since the rising speed (time change rate) of the turbine rotation speed varies depending on the load of the vehicle, the vehicle speed, etc., a shift shock may occur.
10A shows a case where the change rate of the turbine rotational speed is large, and FIG. 10B shows a case where the change rate of the turbine rotational speed is small.
In FIG. 10A, since the rate of change of the turbine speed is large, the time (t4 to t5) from the synchronous prediction until the speed at the second speed is reached is shorter than the hydraulic response time Tr, and the turbine speed Since the engagement side engaging element completes the engagement after reaching the rotation speed at the second speed, the turbine rotation speed is blown up (engine rotation is blown up).
In FIG. 10B, since the rate of change of the turbine speed is small, the time (t4 to t5) from the synchronous prediction until the speed at the second speed is reached is longer than the hydraulic response time Tr, and the turbine speed. Engagement-side engagement elements are completely engaged before the rotation speed at the second speed is reached, and a lifting shock (shift shock) of the turbine rotation speed is generated.

In Patent Document 1, in a downshift in a power-on state, the hydraulic pressure of the engagement element on the engagement side is increased to a predetermined pressure lower than the engagement pressure with a predetermined gradient, and then a gentler gradient than the predetermined gradient. What is controlled so that it raises by this is disclosed.
This control method prevents engine blow-up and shift shock due to variations in the first fill state of the engagement element on the engagement side. Therefore, it is not possible to prevent the occurrence of a shock due to the fluctuation of the time change rate of the turbine rotation speed due to the vehicle load or the vehicle speed.
JP 2002-156033 A

Patent Document 2 discloses a shift control device that applies a high engagement hydraulic pressure when the turbine rotation speed after shifting is lower by a predetermined rotation speed. That is, as in FIG. 9, the synchronization prediction is detected, and the maximum hydraulic pressure is supplied to the engagement element on the engagement side at that time to be engaged. In particular, at the time of low speed, immediately before supplying the maximum hydraulic pressure to the engagement element on the engagement side, a predetermined hydraulic pressure is supplied to the engagement element on the release side, thereby completing the shift without performing synchronization determination. .
This control method also cannot prevent the occurrence of shock due to the fluctuation of the time change rate of the turbine rotational speed.
JP-A-7-208597

In Patent Document 3, the rising slope of the clutch hydraulic pressure is set so that the engagement time from when the clutch hydraulic pressure rises until the engagement is completed is substantially constant according to the magnitude of the vehicle body load. That controls an electromagnetic proportional control valve based on the above.
In general, as a method of controlling the clutch hydraulic pressure, there are a case where the clutch hydraulic pressure is directly controlled by an electromagnetic proportional control valve and a case where the electromagnetic proportional control valve is used as a pilot valve and the clutch hydraulic pressure is controlled by the hydraulic control valve. However, in any case, when the command signal to the electromagnetic proportional control valve is changed, the clutch hydraulic pressure does not respond with high accuracy and the followability is poor. For this reason, even if the clutch hydraulic pressure is controlled by the electromagnetic proportional control valve, it is difficult to control the clutch hydraulic pressure to the set ramp-up gradient, and a shock cannot be avoided.
JP 2000-304124 A

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automatic transmission that can prevent shift shock and engine rotation from being blown by applying an engagement hydraulic pressure at an appropriate timing even when the input speed increases at different speeds during a power-on downshift. It is an object of the present invention to provide a speed change control method.

In order to achieve the above object, an invention according to claim 1 is an automatic transmission that releases a first engagement element and engages a second engagement element at the time of downshift. At the time of downshift command, the hydraulic pressure of the first engagement element is controlled to bring the input rotation speed close to the low speed rotation speed, and when the input rotation speed approaches the low speed rotation speed, the second engagement element In the shift control method for outputting the engagement hydraulic pressure for completing the shift, a step of obtaining a time change rate of the input rotation speed during the shift, and a low speed from the input rotation speed during the shift and the time change rate thereof. The engagement hydraulic pressure is output to the second engagement element so that the time to reach the input rotation speed of the stage and the estimated time and the response time of the engagement hydraulic pressure of the second engagement element are approximated Determining when to perform, And outputting the engagement oil pressure to the second engagement element at serial time, provides a shift control method for an automatic transmission having a.

The invention according to claim 2 is an automatic transmission that releases the first engagement element during downshift and engages the second engagement element. When the downshift command is issued in the power-on state, the first transmission is performed. When the input rotational speed approaches the rotational speed of the low speed stage by controlling the hydraulic pressure of the engagement element, and the input engaging speed increases from the rotational speed of the low speed stage to a rotational speed lower by the set rotational speed, the second engaging element In the shift control method for outputting the engagement hydraulic pressure for completing the shift, the step of obtaining the time change rate of the input rotation speed during the shift and the time change rate of the input rotation speed during the shift The step of correcting the set rotational speed, the step of correcting so that the response time of the engagement hydraulic pressure of the second engagement element approximates the time required to reach the input rotational speed of the low speed stage, and the input The number of rotations It provides a shift control method of an automatic transmission and a step of outputting the second engagement element into engagement hydraulic pressure at the time of rising from a few to the corrected set number of revolutions only low rotational speed.

First, a method according to claim 1 will be described.
Conventionally, when the input rotational speed rises to a value lower than the rotational speed of the low speed stage by a predetermined rotational speed, the engagement hydraulic pressure for completing the shift is output to the second engagement element (engagement-side engagement element). However, in the present invention, the output timing of the engagement hydraulic pressure to the second engagement element is not determined by the input rotation speed, but the input rotation speed of the low speed stage is reached from the input rotation speed and its time change rate. The timing until the engagement hydraulic pressure is output to the second engagement element is determined so that the estimated time and the response time of the engagement hydraulic pressure of the second engagement element approximate. Here, the approximation of the estimated time and the response time of the engagement hydraulic pressure of the second engagement element includes not only the case where both times are completely coincident but also the case where they are almost coincident with some errors.
The input speed increase rate (time change rate) during a power-on downshift varies depending on the vehicle load, vehicle speed, etc., but the time to reach the low speed input speed is the input speed during shifting. And its time change rate can be estimated by calculation. The response time of the engagement hydraulic pressure of the second engagement element can be obtained almost accurately because the hydraulic pressure rises with a substantially constant characteristic when a predetermined stepped command signal is input to the solenoid valve. it can. Therefore, after the stepped command signal is input to the solenoid valve, the time until the hydraulic pressure of the second engagement element rises and reaches the engagement hydraulic pressure at the completion of the shift, and the input rotational speed increases to the rotational speed of the low speed stage. By approximating the time to perform, it is possible to eliminate the occurrence of the rising of the input rotation speed and the lifting shock.
Thus, even when the speed of increase of the input rotational speed is different, by applying the engagement hydraulic pressure at an appropriate timing, it is possible to prevent a shift shock or an increase in engine rotation.

According to the first aspect of the present invention, the time required to reach the low-speed input rotational speed is estimated from the input rotational speed and the time change rate thereof, and the estimated time and the hydraulic response time of the second engagement element are approximated. Although the timing for outputting the engagement hydraulic pressure to the second engagement element has been determined, in claim 2, the set rotation speed n2 (see FIG. 9) at the time of synchronization prediction is corrected from the time change rate of the input rotation speed, and the input rotation The engagement hydraulic pressure is output to the second engagement element when the number increases from the rotation speed at the low speed stage to a rotation speed that is lower by the corrected rotation speed n2. The set rotational speed n2 is corrected so that the response time of the engagement hydraulic pressure of the second engagement element approximates the time required to reach the low speed stage input rotational speed. Therefore, when the time change rate of the input rotation speed increases, the set rotation speed is corrected to a large value accordingly.
Also in this case, the timing for outputting the engagement hydraulic pressure can be determined so that the hydraulic pressure response time and the time for the input rotation speed to rise to the low speed rotation speed can be approximated. Occurrence can be eliminated.

The hydraulic pressure of the second engagement element rises with a substantially constant characteristic when a predetermined stepped command signal is input to the solenoid valve, but when the oil temperature is low, the hydraulic pressure rise characteristic is greatly different from that at a high temperature. . That is, the response time of the engagement hydraulic pressure of the second engagement element varies depending on the oil temperature.
Accordingly, in claim 3, a step of correcting the response time of the engagement hydraulic pressure of the second engagement element with the oil temperature is provided.
Specifically, the response time is corrected to be longer at low temperatures. By this correction, the engagement hydraulic pressure can be applied at an appropriate timing regardless of the change in the oil temperature.

As is apparent from the above description, according to the first aspect of the present invention, the time required to reach the input rotational speed of the low speed stage is estimated from the input rotational speed and the time change rate thereof, Since the timing of outputting the engagement hydraulic pressure to the second engagement element is determined so that the response time of the engagement hydraulic pressure of the two engagement elements is approximate, the first rotation speed is reached when the input rotation speed reaches the low speed rotation speed. The hydraulic pressure of the two engaging elements can also reach the hydraulic pressure in the engaged state. Therefore, even when the rising speed of the input rotational speed is different, it is possible to prevent a shift shock and an engine rotational speed.

According to the second aspect of the invention, the set rotational speed at the time of synchronization prediction is corrected from the time change rate of the input rotational speed, and the input rotational speed is reduced from the rotational speed of the low speed stage by the corrected rotational speed. Since the engagement hydraulic pressure is output to the second engagement element at the time of the rise, it is possible to approximate the response time of the engagement hydraulic pressure of the second engagement element and the time until the low speed stage input rotational speed is reached. As in the first aspect, even when the rising speed of the input rotational speed is different, it is possible to prevent a shift shock and an engine rotational speed.

Embodiments of the present invention will be described below with reference to examples.

FIG. 1 shows an example of a vehicle system equipped with an automatic transmission according to the present invention.
The output of the engine 1 is transmitted to the transmission mechanism 4 via the torque converter 3 of the automatic transmission 2, and the transmission mechanism 4 is connected to wheels (not shown) via the output shaft 5. The automatic transmission 2 includes an oil pump 6 that is driven by the engine 1 via the torque converter 3, and the discharge pressure of the oil pump 6 is sent to the hydraulic control device 7. The hydraulic control device 7 includes first to third solenoid valves 21 to 23 for speed change control. By controlling these solenoid valves 21 to 23 with the AT controller 20, various mechanisms built in the speed change mechanism 4 are provided. The hydraulic pressure of the combined element is controlled according to the traveling state. As the solenoid valves 21 to 23, not only linear solenoid valves but also duty solenoid valves can be used.
The hydraulic pressure control device 7 may be provided with other solenoid valves for lock-up clutch control and line pressure control in addition to the shift control solenoid valves 21 to 23.

Signals such as engine speed, throttle opening, turbine speed (input speed), vehicle speed, shift position, and ATF oil temperature are input to the AT controller 20. The memory of the AT controller 20 stores a power on / off determination value map in addition to the shift map. From the input signal, it is determined whether the power is on or off based on the determination map, and the gear position is determined based on the shift map based on the vehicle speed and the throttle opening at that time, and the solenoid valves 21 to 23 are controlled.
Note that signals other than those described above may be input to the AT controller 20.

FIG. 2 shows an example of the speed change mechanism 4.
The speed change mechanism 4 includes an input shaft 10 to which engine power is transmitted via a torque converter 3, three clutches C1 to C3 and two brakes B1 and B2, which are friction engagement elements, a one-way clutch F, and a Ravigneaux type planet. A gear mechanism 11 and a differential device 14 are provided.

The forward sun gear 11a and the input shaft 10 of the planetary gear mechanism 11 are connected via a C1 clutch, and the rear sun gear 11b and the input shaft 10 are connected via a C2 clutch. The carrier 11c is connected to the center shaft 15, and the center shaft 15 is connected to the input shaft 10 via a C3 clutch. The carrier 11c is connected to the transmission case 16 via a B2 brake and a one-way clutch F that allows only forward rotation (engine rotation direction) of the carrier 11c. The carrier 11c supports two types of pinion gears 11d and 11e, the forward sun gear 11a meshes with a long pinion 11d having a long axial length, and the rear sun gear 11b meshes with the long pinion 11d via a short pinion 11e having a short axial length. . A ring gear 11f that meshes only with the long pinion 11d is coupled to the output gear 12. The output gear 12 is connected to the differential device 14 via the intermediate shaft 13.

The transmission mechanism 4 realizes four forward speeds and one reverse speed as shown in FIG. 3 by operating the clutches C1, C2, C3, the brakes B1, B2, and the one-way clutch F. In FIG. 3, ● represents the action state of hydraulic pressure. The B2 brake is engaged at the time of reverse and the first speed in the L range. FIG. 3 also shows operating states of the first to third solenoid valves (SOL1 to SOL3) 21 to 23. ○ indicates an energized state, and x indicates a non-energized state. This operation table shows the operation in a steady state.

In this embodiment, the first solenoid valve 21 is for B1 brake control, the second solenoid valve 22 is for C2 clutch control, and the third solenoid valve 23 is for both C3 clutch control and B2 brake control. Yes. The reason why the third solenoid valve 23 is used for both C3 clutch control and B2 brake control is that the B2 brake does not operate in the D range and is used only in the engine brake control in the L range and the transient control in the R range. This is because it does not interfere with the C3 clutch operated in the D range.
In this embodiment, the first solenoid valve 21 is normally closed and the second and third solenoid valves 22 and 23 are normally open.

FIG. 4 shows a shift control method in the power-on downshift from the third speed to the second speed in the automatic transmission 2 having the above configuration. At the time of downshift from the 3rd speed to the 2nd speed, the engagement element on the engagement side indicates the B1 brake, and the engagement element on the release side indicates the C3 clutch. Note that the hydraulic control of the engagement element C3 clutch on the disengagement side is the same as that in FIG. 9 and is omitted in FIG.
4A shows a case where the time change rate of the turbine speed is large, and FIG. 4B shows a case where the time change rate of the turbine speed is small. Since the control from time t1 to t3 is the same as that in FIG.
If the time change rate of the turbine rotation speed is large as shown in FIG. 4 (a), conventionally, synchronization prediction is performed at time t4, and the B1 brake, which is the engagement element on the engagement side, is engaged from this point in time. The hydraulic pressure is output. In this embodiment, the time required to reach the speed of the second gear is estimated from the current turbine speed and the rate of change over time, and the relationship between the estimated time and the second engagement element is estimated. The timing t6 at which the engagement hydraulic pressure is output to the B1 brake is determined so as to approximate the response time Tr of the combined hydraulic pressure, and the engagement hydraulic pressure is output to the B1 brake at this timing t6. Therefore, when the turbine speed reaches the second speed (t5), the hydraulic pressure of the B1 brake also reaches the hydraulic pressure in the engaged state, preventing the turbine rotational speed from blowing up due to the delay in the engagement of the B1 brake. it can.
Even when the time change rate of the turbine rotation speed is small as shown in FIG. 4B, the time until the rotation speed of the second gear is reached is estimated from the current turbine rotation speed and the time change rate. The timing t6 at which the engagement hydraulic pressure is output to the B1 brake is determined so that the estimated time approximates the response time Tr of the engagement hydraulic pressure of the second engagement element, and the engagement hydraulic pressure is output to the B1 brake at this timing t6. ing. Therefore, when the turbine speed reaches the second speed (t5), the hydraulic pressure of the B1 brake also reaches the engaged hydraulic pressure, and the shock of lifting the turbine speed due to the early engagement of the B1 brake. Can be prevented.

FIG. 5 shows a flow of the speed change control method shown in FIG. 4, particularly the hydraulic control of the B1 brake.
First, it is determined whether or not a power-on shift command from the third speed to the second speed has been issued (step S1). When a shift command is issued, initial control is performed (step S2). The initial control refers to a series of controls such as backpacking, standby pressure output, and out-of-synchronization detection (see FIG. 9).
Next, the turbine rotational speed at the second gear is calculated from the turbine rotational speed at the time of the shift command (step S3), and the time change rate of the turbine rotational speed during the shift is calculated (step S4). Since the turbine rotation speed is measured at a constant time interval, the time change rate can be easily calculated by dividing the difference in turbine rotation speed at the time interval by the time interval.
Next, the time (estimated time) for the turbine rotation speed to reach the rotation speed of the second speed stage is calculated from the turbine rotation speed at the present time, the time change rate thereof, and the turbine rotation speed at the second speed stage (step S5). ).
Next, the estimated time obtained by calculation is compared with the hydraulic response time Tr of the B1 brake (step S6). The hydraulic pressure response time Tr is a time during which the engagement hydraulic pressure of the B1 brake increases to the hydraulic pressure at the completion of engagement after the command signal is output to the first solenoid valve 21. If the estimated time is longer than the hydraulic response time Tr, the control after step 4 is repeated. If the estimated time is equal to or shorter than the hydraulic pressure response time Tr, a command signal is output to the first solenoid valve 21 and the engagement hydraulic pressure is output to the B1 brake (step S7).
By performing hydraulic control along the above flow, a power-on downshift without a shock is performed.

In the above embodiment, the oil pressure response time Tr has been described as being constant, but actually varies depending on the ATF oil temperature. That is, since the viscosity increases when the oil temperature is low, the hydraulic pressure response time Tr tends to be longer than when the oil temperature is high. Therefore, when the oil temperature is low, by setting the oil pressure response time Tr longer, a power-on downshift without a shock can be performed regardless of the oil temperature change.

FIG. 6 shows a shift control method in the power-on downshift from the third speed to the second speed in the automatic transmission 2 configured as described above.
6A shows a case where the time change rate of the turbine speed is large, and FIG. 6B shows a case where the time change rate of the turbine speed is small. The control from time t1 to t3 is the same as in FIG.
When the time change rate of the turbine rotation speed is large as shown in FIG. 6A, the set rotation speed (n2) at the time of synchronous prediction is corrected from the time change rate of the turbine rotation speed, and the turbine rotation speed is the second speed stage. The engagement hydraulic pressure is output to the B1 brake at the time when the rotation speed increases to a rotation speed that is lower by the corrected rotation speed n2 ′.
For example, as shown in FIG. 7, the relationship between the time change rate of the turbine rotation speed and the correction value n2 ′ is set in advance by a map or a calculation formula, and the map or calculation formula and the turbine rotation speed are corrected. The set rotational speed may be obtained from the time change rate of the number. The map or the calculation formula is set so that the hydraulic response time Tr of the B1 brake and the time required to reach the turbine speed of the second gear stage are approximated when the turbine speed increases at the change rate. . In FIG. 7, the solid line indicates a high temperature of the ATF oil temperature, the broken line indicates a low temperature, and the correction value n2 ′ is set to a higher value when the temperature is low.
Thus, when the time change rate of the turbine rotational speed is large, the turbine rotational speed is increased from the rotational speed at the second speed to a lower value by the set rotational speed n2 ′ by correcting the set rotational speed n2 ′ high. If the engagement hydraulic pressure is output to the B1 brake at the time of synchronization (when the synchronization is predicted), the hydraulic pressure of the B1 brake reaches the engagement completed hydraulic pressure when the turbine rotation speed reaches the rotation speed of the second gear (t5). In addition, it is possible to prevent the turbine speed from being increased due to the delay in engagement of the B1 brake.
Even when the time change rate of the turbine speed is small as shown in FIG. 6B, the set speed n2 ′ is corrected from the time change rate of the turbine speed, and the turbine speed is set from the speed at the second speed. It is only necessary to output the engagement hydraulic pressure to the B1 brake at the time when the rotation speed is increased to a value lower by n2 ′ (during synchronization prediction). In this case, since the set rotational speed n2 ′ is corrected to be low, it is possible to prevent a shock of raising the turbine rotational speed due to the early engagement of the B1 brake.

FIG. 8 shows the flow of the shift control method shown in FIG. 6, particularly the hydraulic control of the B1 brake.
The control from step S1 to S4 is the same as in FIG.
After calculating the time change rate of the turbine rotation speed, the set rotation speed n2 ′ is corrected (step S8). That is, the corrected set rotational speed n2 ′ is obtained from the time change rate of the turbine rotational speed using the map or calculation formula shown in FIG.
Next, a value obtained by subtracting the corrected set rotational speed n2 ′ from the turbine rotational speed in the second gear is compared with the current turbine rotational speed (step S9). If the current turbine speed is low, the control from step 4 is repeated, and if the current turbine speed is high, a command signal is output to the first solenoid valve 21 and the engagement hydraulic pressure is output to the B1 brake ( Step S7).
By performing hydraulic control along the above flow, a power-on downshift without a shock is performed.
In this embodiment as well, it goes without saying that the correction value n2 ′ of the set rotational speed can be varied by the ATF oil temperature.

In the above embodiment, the shift control at the time of power-on downshift from the 3rd speed to the 2nd speed has been described as an example, but the power on from other speed stages, for example, the 4th speed to the 3rd speed, the 2nd speed to the 1st speed, etc. The same applies to downshifts.
4 and 6, as in FIG. 9, as the engagement control of the engagement side engagement element B <b> 1, the control is performed in which the hydraulic pressure is increased in a stepwise manner and then increased in a predetermined gradient. After being raised, it may be held at a constant pressure, or may be raised stepwise up to the maximum pressure. Further, the hydraulic pressure may be increased to the maximum pressure at time t5, and the end process after the engagement control can be omitted.

It is a system diagram carrying the automatic transmission for vehicles in the present invention. FIG. 2 is a skeleton diagram of a transmission mechanism of the automatic transmission of FIG. 1. 3 is an operation table of each friction engagement element and solenoid valve of the speed change mechanism shown in FIG. 2. It is a time change figure of turbine rotation speed at the time of power-on downshift using the 1st example of the control method concerning the present invention, indication current of engagement side engagement element B1, and oil pressure. It is a flowchart figure of the control method shown in FIG. It is a time change figure of turbine rotation speed at the time of power-on downshift using the 2nd example of a control method concerning the present invention, indication current of engagement side engagement element B1, and oil pressure. It is a figure which shows the relationship between a setting rotation speed and the time change rate of a turbine rotation speed. It is a flowchart figure of the control method shown in FIG. It is a time change figure of turbine rotation speed at the time of power-on downshift using the conventional shift control method, instruction current and oil pressure of an engagement side engagement element, indication current of a release side engagement element, and oil pressure. It is a time change figure of the turbine rotation speed, the instruction | indication current of an engagement side engaging element, and oil_pressure | hydraulic in case the time change rates of the turbine rotation speed in the past differ.

Explanation of symbols

B1 engaging element C3 on the engagement side engagement element 20 on the release side AT controller 21 B1 solenoid valve for brake control 23 C3 solenoid valve for clutch control

Claims (3)

An automatic transmission that releases a first engagement element and engages a second engagement element during downshifting,
At the time of downshift command in the power-on state, the hydraulic pressure of the first engagement element is controlled to bring the input rotational speed closer to the low speed rotational speed, and when the input rotational speed approaches the low speed rotational speed, In the shift control method for outputting the engagement hydraulic pressure for completing the shift to the two engagement elements,
Obtaining a time change rate of the input rotational speed during the shift;
Estimating the time required to reach the input rotational speed of the low speed stage from the input rotational speed in the middle of the shift and its time change rate;
Determining the timing for outputting the engagement hydraulic pressure to the second engagement element so that the estimated time approximates the response time of the engagement hydraulic pressure of the second engagement element;
And a step of outputting an engagement hydraulic pressure to the second engagement element at the above timing. An automatic transmission that releases a first engagement element and engages a second engagement element during downshifting,
At the time of downshift command in the power-on state, the hydraulic pressure of the first engagement element is controlled to bring the input rotation speed closer to the low speed rotation speed, and the input rotation speed is lower than the low speed rotation speed by the set rotation speed. In the shift control method for outputting the engagement hydraulic pressure for completing the shift to the second engagement element at the time when the rotation speed is increased.
Obtaining a time change rate of the input rotational speed during the shift;
The step of correcting the set rotational speed based on the time change rate of the input rotational speed in the middle of the shift, until the response time of the engagement hydraulic pressure of the second engagement element and the input rotational speed of the low speed stage are reached. Correcting to approximate time, and
And a step of outputting an engagement hydraulic pressure to the second engagement element when the input rotation speed increases to a rotation speed that is lower than the rotation speed of the low speed stage by a corrected setting rotation speed. Method. The shift control method for an automatic transmission according to claim 1, further comprising a step of correcting a response time of the engagement hydraulic pressure of the second engagement element with an oil temperature.

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