JP3752401B2 - Shift control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shift control device for an automatic transmission. More specifically, the present invention relates to a structure that releases a high-speed stage friction engagement element and performs a downshift by changing a friction engagement element that fastens a low-speed stage friction engagement element. Related to the device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known an automatic transmission configured to release a high-speed stage frictional engagement element while performing a downshift by changing a frictional engagement element that fastens a low-speed stage frictional engagement element.
[0003]
In the one disclosed in Japanese Patent Laid-Open No. 6-341526, when switching downshifting, the hydraulic pressure on the fastening side is kept at a predetermined low pressure, and when the input rotational speed of the transmission reaches the synchronization point of the low speed stage, While the pressure is increased from the low pressure, the release side hydraulic pressure is drained when a predetermined time has elapsed from the synchronization, and the predetermined time is changed according to the input torque and oil temperature of the transmission. ing.
[0004]
Further, in the one disclosed in Japanese Patent Application Laid-Open No. 9-133205, in the change downshift, the transmission torque capacity of the friction engagement element on the high speed side is a value at which the output shaft torque does not become negative within the first time at the beginning of the shift. In the second time thereafter, the transmission torque capacity of the friction engagement element on the high speed side is increased to the same level as the input shaft torque, and the transmission torque capacity of the friction engagement element on the low speed side is set appropriately. After the second time, the transmission torque capacity of the low speed side frictional engagement element is increased to the input shaft torque or more, and the high speed side frictional engagement element is released.
[0005]
[Problems to be solved by the invention]
By the way, in the one disclosed in Japanese Patent Laid-Open No. 6-341526, the engagement of the friction engagement element for the low speed stage (fastening side) from the time when the input rotational speed of the automatic transmission reaches the synchronization point of the low speed stage. While rapidly increasing the hydraulic pressure, the engagement hydraulic pressure of the friction engagement element for the high speed stage (release side) is drained from the time when the time corresponding to the conditions such as the input torque and oil temperature has elapsed from the synchronization point. Yes.
[0006]
The above configuration corresponds to the response delay of the fastening hydraulic pressure with respect to the drain. However, with such a configuration, there is a problem that it takes a long time from when the synchronization point is reached until the switching is actually started.
[0007]
Further, in the one disclosed in Japanese Patent Laid-Open No. 9-133205, the engagement hydraulic pressure is controlled based on the elapsed time without detecting the synchronization. There is a problem in that the time until the start of the increase of the time becomes longer, and further, when it is attempted to cope with the delay in the increase of the engagement hydraulic pressure, the replacement is delayed.
[0008]
The present invention has been made in view of the above problems, and is configured to release a high-speed stage frictional engagement element and to perform a downshift by changing the frictional engagement element that fastens the low-speed stage frictional engagement element. In the automatic transmission shift control device, the switching is performed at an early timing while performing the switching at the optimum timing corresponding to the increase in the engagement hydraulic pressure of the engagement side frictional engagement element (low-speed stage frictional engagement element). An object of the present invention is to provide a shift control device for an automatic transmission that can be performed.
[0009]
[Means for Solving the Problems]
Therefore, the invention according to claim 1 is an automatic transmission configured to release a high-speed stage frictional engagement element and perform a downshift by changing the frictional engagement element that fastens the low-speed stage frictional engagement element. In the transmission control device,
With the engagement hydraulic pressure of the low-speed stage friction engagement element held at the standby pressure, the engagement hydraulic pressure of the high-speed stage friction engagement element is decreased, and the gear ratio (= input shaft rotation speed / output shaft rotation speed). ) Becomes the feedback start gear ratio, the actual input shaft rotation speed is added to the target input shaft rotation speed. The In order to match, the feedback control for correcting the engagement hydraulic pressure of the high-speed stage friction engagement element is started,
The engagement hydraulic pressure of the low-speed stage friction engagement element is equivalent to the inertia torque from the standby pressure until the second engagement start gear ratio is larger than the first engagement start gear ratio that is larger than the feedback start gear ratio. Up to pressure,
The engagement hydraulic pressure of the low-speed stage friction engagement element is calculated from the inertia torque equivalent pressure and the input shaft torque at that time is the low-speed stage friction in the first predetermined time after the second engagement start gear ratio is reached. Increasing change to hydraulic pressure that can be transmitted only with the engagement element,
The feedback control is terminated when the feedback end gear ratio is larger than the second engagement start gear ratio, and then the engagement hydraulic pressure of the high-speed stage friction engagement element is reduced to 0 in a second predetermined time. It was set as the structure made to do.
[0010]
According to such a configuration, first, in a state where the engagement hydraulic pressure of the low speed stage frictional engagement element on the fastening side is held at the standby pressure, the engagement hydraulic pressure of the high speed stage frictional engagement element on the release side is decreased, When the feedback start gear ratio is reached, the actual input shaft rotational speed is then added to the target input shaft rotational speed until the feedback end gear ratio is reached. The The engagement hydraulic pressure of the high-speed stage frictional engagement element is feedback-controlled so as to match, and the engagement hydraulic pressure of the high-speed stage frictional engagement element is reduced to zero within a second predetermined time after the feedback end gear ratio is reached. Decrease.
On the other hand, the engagement hydraulic pressure of the low-speed stage frictional engagement element is from the standby pressure until the second engagement start gear ratio is larger than the first engagement start gear ratio larger than the feedback start gear ratio. The inertia torque is increased to the equivalent pressure of the inertia torque, and at the first predetermined time after reaching the second engagement start gear ratio, the input shaft torque at that time is changed from the inertia torque equivalent pressure only to the low-speed stage friction engagement element. The oil pressure is increased to a level that can be transmitted with
[0018]
Claim 2 In the described invention, the engagement hydraulic pressure of the low-speed stage friction engagement element is increased. First Decrease the engagement hydraulic pressure of the high-speed stage friction engagement element for a predetermined time. Second The predetermined time is changed in accordance with the type of shift and / or the type of friction engagement element.
[0019]
According to this configuration, the fastening speed of the low-speed stage frictional engagement element and the release speed of the high-speed stage frictional engagement element are the types of speed change at that time (4th speed → 3rd speed, 3rd speed → 2nd speed, etc. It is changed according to the type of downshift) and the frictional engagement elements (types of clutch and brake) to be engaged / released.
[0020]
【The invention's effect】
According to the invention of claim 1, The fastening of the low-speed stage frictional engagement element and the release of the high-speed stage frictional engagement element can be started at appropriate timings, respectively. It is possible to avoid the occurrence or the occurrence of a blow-up due to the delay in fastening with respect to release. There is an effect.
[0024]
Claim 2 According to the described invention, the engagement hydraulic pressure can be increased (engaged) and decreased (released) at an appropriate speed according to the type of shift and the type of friction engagement element. In addition, there is an effect that it is possible to always perform optimum switching control regardless of the type of friction engagement element.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
FIG. 1 shows a transmission mechanism of an automatic transmission according to an embodiment, and an engine output is transmitted to a transmission mechanism 2 via a torque converter 1.
[0026]
The transmission mechanism 2 includes two sets of planetary gears G1, G2, three sets of multi-plate clutches H / C, R / C, L / C, one set of brake bands 2 & 4 / B, and one set of multi-plate brakes L & R /. B, one set of one-way clutch L / OWC.
[0027]
The two sets of planetary gears G1 and G2 are simple planetary gears composed of sun gears S1 and S2, ring gears r1 and r2, and carriers c1 and c2, respectively.
The sun gear S1 of the planetary gear set G1 is configured to be connectable to the input shaft IN by a reverse clutch R / C, and is configured to be fixed by a brake band 2 & 4 / B.
[0028]
The sun gear S2 of the planetary gear set G2 is directly connected to the input shaft IN.
A carrier c1 of the planetary gear set G1 is configured to be connectable to the input shaft I by a high clutch H / C, while a ring gear r2 of the planetary gear set G2 is a carrier of the planetary gear set G1 by a low clutch L / C. The carrier c1 of the planetary gear set G1 can be fixed by a low & reverse brake L & R / B.
[0029]
A ring gear r1 of the planetary gear set G1 and a carrier c2 of the planetary gear set G2 are directly and integrally connected to the output shaft OUT.
In the speed change mechanism 2 configured as described above, the first to fourth speeds and the reverse are realized by a combination of engagement states of the respective clutches and brakes as shown in FIG.
[0030]
In FIG. 2, the circles indicate the engaged state, and the parts not marked with the symbol indicate that they are in the open state. In particular, the engaged state indicated by the black circle of the low & reverse brake L & R / B in the first speed. Indicates fastening in only one range.
[0031]
According to the combination of engagement states of the clutches and brakes shown in FIG. 2, for example, at the time of downshift from the 4th speed to the 3rd speed, the brake band 2 & 4 / B is released and the low clutch L / C is engaged. When downshifting from 3rd to 2nd, the high clutch H / C is released and the brake band 2 & 4 / B is engaged. When upshifting from 2nd to 3rd, the brake band 2 & 4 / B And the high clutch H / C are engaged, and at the time of upshift from the third speed to the fourth speed, the low clutch L / C is released and the brake band 2 & 4 / B is engaged. As described above, a shift in which the engagement and release of the clutch and brake (friction engagement element) are controlled simultaneously to change the friction engagement element is referred to as a change shift. To.
[0032]
The clutches and brakes (friction engagement elements) are operated by supply hydraulic pressures, and the supply hydraulic pressures for the clutches and brakes are adjusted by various solenoid valves included in the solenoid valve unit 11 shown in FIG. The
[0033]
The A / T controller 12 for controlling the various solenoid valves of the solenoid valve unit 11 includes an A / T oil temperature sensor 13, an accelerator opening sensor 14, a vehicle speed sensor 15, a turbine rotation sensor 16, an engine rotation sensor 17, and an air flow meter. Detection signals from 18 etc. are input, and the engagement hydraulic pressure in each friction engagement element is controlled based on these detection results.
[0034]
In FIG. 3, reference numeral 20 indicates an engine combined with the automatic transmission.
Here, referring to the time chart of FIG. 4, an example of a downshift accompanying the depression of the accelerator (hereinafter referred to as “power-on-down”) is shown in FIG. This will be described with reference to the flowchart of FIG.
[0035]
The flowchart of FIG. 5 shows a main control routine common to the engagement side frictional engagement element and the release side frictional engagement element.
In step S1, a power on / down shift determination is performed.
[0036]
The A / T controller 12 stores in advance a shift map in which shift speeds are set according to the vehicle speed VSP and the accelerator opening (throttle opening). For example, the current (pre-shift) shift speed and the shift speed are stored. A state that is different from the shift speed searched from the map, is in the downshift direction, and the accelerator is not fully closed is determined as a power-on-down shift.
[0037]
When the power on / down shift determination is made, the process proceeds to step S2, and the gear ratio (gear) calculated at that time is calculated as the ratio between the input shaft rotation speed (turbine rotation speed) and the output shaft rotation speed (vehicle speed) of the transmission mechanism. It is determined whether or not the ratio = input shaft rotational speed / output shaft rotational speed is higher than the feedback (F / B) start gear ratio set based on the gear ratio before the shift.
[0038]
The determination of whether or not the gear ratio is higher than the F / B start gear ratio is to determine the start of change of the gear ratio due to slipping of the disengagement friction engagement element, and the F / B start gear The ratio is set as a gear ratio that is slightly higher than the gear ratio before the shift.
[0039]
When the gear ratio is less than or equal to the F / B start gear ratio, the preparation phase process of step S3 is executed.
The preparation phase process of step S3 is divided into a release-side process and a fastening-side process, and the release-side preparation phase process is shown in the flowcharts of FIGS.
[0040]
The flowchart of FIG. 6 shows the main routine of the release side (for high speed stage) friction engagement element preparation phase processing. In step S31, the type of shift and the type of friction engagement element to be controlled for release are shown. It is determined whether or not a predetermined time TIMER1 stored in advance has elapsed from the shift determination.
[0041]
If it is within the predetermined time TIMER1, the process proceeds to step S32, and the release initial hydraulic pressure is calculated. The release initial hydraulic pressure is a target value for reducing the hydraulic pressure to near the critical pressure while maintaining a completely engaged state from the hydraulic pressure at the time of non-shifting. Note that the entire hydraulic control of the disengagement side frictional engagement element in the preparation phase corresponds to the control of the initial shift hydraulic pressure in the present invention.
[0042]
The calculation of the release initial hydraulic pressure in step S32 is shown in detail in the flowchart of FIG. 7. In step S321, the non-shifting hydraulic pressure Po0 of the friction engagement element that performs the release control this time and the release of the friction engagement element are shown. The initial hydraulic pressure Po1 is calculated.
[0043]
The non-shifting hydraulic pressure Po0 is:
Po0 = K1 × (Tt × Tr-o × allowance (0)) + Prtn-o
Is calculated as
[0044]
Here, K1 is a coefficient for converting the transmission torque capacity (necessary transmission torque capacity) of the friction engagement element on the release side into hydraulic pressure, and depends on the type of shift and the type of friction engagement element to be controlled to release. Stored in advance. Tt is an estimated value of the input shaft torque of the speed change mechanism, and is estimated from, for example, the engine output torque estimated from the intake air amount, the engine rotational speed, and the like, and the torque ratio of the torque converter. Tr-o is a critical torque ratio for obtaining a critical transmission torque capacity at which the friction engagement element slips with respect to the input shaft torque Tt. The margin (0) is a correction coefficient for adding a margin torque capacity to the critical transmission torque capacity, and is stored in advance as a value of about 3.0, for example. Prtn-o is a release-side standby pressure (release-side return spring pressure), and is stored in advance for each friction engagement element.
[0045]
On the other hand, the release initial hydraulic pressure Po1 is
Po1 = K1 × (Tt × Tr-o × margin (1)) + Prtn-o
Is calculated as
[0046]
That is, only the margin portion is different from the calculation formula for the non-shifting hydraulic pressure Po0, and the calculation formula for the release initial hydraulic pressure Po1 uses a relatively low value of about 1.2 for the margin allowance (1).
[0047]
The margin (1) (= about 1.2) is set as a value that allows the disengagement side frictional engagement element to maintain the engaged state even if the estimation error of the input shaft torque occurs within the expected range. .
[0048]
During non-shifting, the non-shifting hydraulic pressure Po0 is controlled, but when releasing in response to a shift request, the non-shifting hydraulic pressure Po0 is reduced from the non-shifting hydraulic pressure Po0 within the predetermined time TIMER1. In step S322, the hydraulic gradient Rmp-Po1 within the predetermined time TIMER1 is
Rmp-Po1 = (Po0-Po1) / TIMER1
Calculate as
[0049]
Then, the hydraulic pressure is reduced by (Rmp-Po1) every unit time from the non-shifting hydraulic pressure Po0, and when the predetermined time TIMER1 has elapsed, the hydraulic pressure is reduced to the release initial hydraulic pressure Po1.
[0050]
Until the predetermined time TIMER1 elapses as described above, after the pressure is reduced to the release initial hydraulic pressure Po1, until it is determined in step S33 that the gear ratio becomes higher than the F / B start gear ratio. In between, the sharing ratio ramp control of step S34 is executed.
[0051]
The details of the sharing ratio ramp control in step S34 are shown in the flowchart of FIG. 8. In step S341, the release initial hydraulic pressure Po1 is calculated, and the release hydraulic pressure Po2 is calculated.
[0052]
The release hydraulic pressure Po2 is
Po2 = K1 × (Tt × Tr-o × margin (2)) + Prtn-o
For example, a value of about 0.8 smaller than 1.0 is used as the margin allowance (2) (margin allowance (0)> room allowance (1)>0> room allowance (2)).
[0053]
Even if the margin (2) (= about 0.8) occurs within an expected range of the input shaft torque estimation error, the disengagement side frictional engagement element can be reliably shifted to the disengaged state. Set as a value. Therefore, the decrease in the hydraulic pressure from the initial release hydraulic pressure Po1 to the release hydraulic pressure Po2 is performed in order to surely shift the friction engagement element on the release side to the release state.
[0054]
In step S342, a hydraulic ramp gradient (unit) for decreasing from the initial release hydraulic pressure Po1 to the release hydraulic pressure Po2 within a predetermined time TIMER2 stored in advance according to the type of shift and the type of friction engagement element to be controlled to release. Hydraulic pressure decrease per hour)
Rmp-Po2 = (Po1-Po2) / TIMER2
(See FIG. 26).
[0055]
Then, the hydraulic pressure is reduced by (Rmp-Po2) per unit time within the predetermined time TIMER2 from the time when the predetermined time TIMER1 has elapsed and in a state where the gear ratio is not higher than the F / B start gear ratio. .
[0056]
The ramp gradient Rmp-Po2 is released within a predetermined range before and after the margin margin becomes 1.0, so that the ramp margin Rmp-Po1 becomes smaller than the gradient Rmp-Po1 by setting the margin variation range and the predetermined time TIMER2. The change in the transmission torque capacity of the side frictional engagement element is made slower than before.
[0057]
When the engagement hydraulic pressure is gradually reduced by the gradient Rmp-Po2, the gear ratio starts to change when the margin becomes near 1.0, and the transmission torque capacity on the disengagement side becomes critical due to the change in the gear ratio. You can know indirectly that it has dropped to nearby.
[0058]
Therefore, when it is detected that the gear ratio starts to change based on the fact that the actual gear ratio is larger than the F / B start gear ratio, the transmission torque capacity (engagement hydraulic pressure) by the gradient Rmp-Po2 is detected. ) Is stopped, and the critical transfer torque capacity is set as a reference value, and the control shifts to feedback control for matching the turbine rotation with the target.
[0059]
Therefore, the feedback control is started in a state where the transmission torque capacity on the disengagement side is accurately controlled to a critical state, and the turbine rotation can be stably controlled without causing a large rotation fluctuation. The fastening side (for low speed stage) friction engagement elements can be fastened at an optimal timing to prevent the occurrence of rotational blow-off and torque contraction.
[0060]
As described above, if the transmission torque capacity change speed is slowed within a predetermined range before and after the margin of margin becomes 1.0, the critical state (slip occurrence) of the disengagement side frictional engagement element is caused as the gear ratio change. Thus, it is possible to ensure the accuracy of the control for obtaining the engagement hydraulic pressure corresponding to the critical transmission torque capacity, and to ensure the responsiveness by decreasing the transmission torque capacity at a relatively high speed in the initial state.
[0061]
On the other hand, the preparation phase process on the fastening side is shown in the flowcharts of FIGS.
The flowchart of FIG. 9 shows the main routine of the preparation phase process on the engagement side (for the low speed stage). In step S41, it is determined whether or not a predetermined time TIMER0 has elapsed since the shift determination. The predetermined time TIMER0 is preferably set according to the oil temperature.
[0062]
If it is determined in step S41 that the predetermined time TIMER0 has not elapsed from the shift determination, the process proceeds to step S42, and hydraulic precharging is performed on the engagement side frictional engagement element.
[0063]
The hydraulic precharge process is shown in the flowchart of FIG. 10, and in step S421, a precharge pressure stored in advance for each friction engagement element is output within the predetermined time TIMER0.
[0064]
When the predetermined time TIMER0 has elapsed, it is determined in step S43 whether or not the gear ratio has become larger than a predetermined engagement start gear ratio (1), and while the gear ratio is equal to or less than the engagement start gear ratio (1). Then, the process proceeds to the standby pressure process in step S44.
[0065]
The engagement start gear ratio (1) is preferably set according to the type of shift and the input shaft torque.
The standby pressure process in step S44 is shown in the flowchart of FIG. 11. In step S441, the standby pressure Prtn-c stored in advance for each friction engagement element is output.
[0066]
Here, returning to the flowchart of FIG. 5, when the gear ratio becomes larger than the F / B start gear ratio in step S2, the process proceeds from step S2 to step S4, where the gear ratio is the gear ratio after the shift. It is determined whether or not the F / B end gear ratio is slightly smaller.
[0067]
If the gear ratio is larger than the F / B start gear ratio but is determined to be equal to or less than the F / B end gear ratio, the inertia phase process of step S5 is executed.
[0068]
The inertia phase process for the release side is shown in the flowcharts of FIGS.
The flowchart of FIG. 12 shows the main routine of the release-side inertia phase process. In step S51, basic control of the release-side hydraulic pressure is performed.
[0069]
The basic control is shown in the flowchart of FIG. 13, and in step S511, an inertia torque (shift torque) Tinr accompanying an increase in rotation due to power-on down is calculated. As shown in FIG. 27, the inertia torque Tinr is stored in advance in a table corresponding to the target shift time, and as the target shift time is shorter, a larger inertia torque (shift torque) Tinr is calculated. It is like that.
[0070]
In step S512, the release side command hydraulic pressure Po3 is calculated.
The release side command hydraulic pressure Po3 is
Po3 = K1 × (Tt-Tinr × HOSEI- _VSP ) × Tr-o + Prtn-o
Is calculated as
[0071]
Where the correction factor HOSEI- _VSP Is a correction term for inertia torque Tinr corresponding to the vehicle speed, and is stored in advance in a table corresponding to vehicle speed VSP, as shown in FIG. 28, and when the vehicle speed falls below, for example, 20 km / h, The torque Tinr is corrected to be smaller, but if it exceeds 20 km / h, the inertia torque Tinr is corrected to be larger as the vehicle speed is increased, for example, it is corrected twice by 40 km / h.
[0072]
Then, from the input shaft torque Tt, “Tinr × HOSEI- _VSP "Is subtracted to correct the inertia torque used for the rotation increase, and the actual transmission torque is obtained. By multiplying this actual transmission torque by the critical torque ratio Tr-o, the actual transmission torque is On the other hand, the transmission torque capacity at which the disengagement side (for high speed stage) friction engagement element is in a critical state (slip generation) can be obtained.
[0073]
In step S52, estimated torque correction is performed.
The estimated torque correction is shown in the flowchart of FIG. 14. In step S521, when the gear ratio becomes larger than the F / B start gear ratio for the first time (that is, the critical point at which the release side frictional engagement element starts to slip). Refer to margin allowance Tr (in the pressure state).
[0074]
Specifically, the margin allowance Tr is calculated backward from the engagement hydraulic pressure of the disengagement side frictional engagement element when the gear ratio becomes larger than the F / B start gear ratio for the first time and the input shaft torque at that time. Ideally, the gear ratio starts to change near the margin of 1.0 (the frictional engagement element on the release side starts to slip). For example, the gear ratio changes with the release side hydraulic pressure corresponding to the margin of 1.1. Assuming that the input shaft torque is estimated to be smaller than the actual value in the estimation of the input shaft torque, it is determined that the hydraulic torque can be maintained in the engaged state due to the margin of the transmission torque capacity. For example, if the gear ratio starts to change at the release side hydraulic pressure corresponding to the margin of margin = 0.9, the input shaft torque is estimated to be larger than the actual value, so that the hydraulic pressure (transfer torque capacity) that cannot maintain the original engagement state has already been reached. Although it is decreasing, it is judged that the start of slipping was delayed.
[0075]
In step S522, the hydraulic pressure correction value ΔP is set to
ΔP = K1 × Tt × Tr-o (1-Tr)
The release side command hydraulic pressure Po3 is corrected by the correction value ΔP to obtain the release side command hydraulic pressure Po4.
[0076]
Po4 = Po3−ΔP
In step S53, turbine rotation feedback control is performed to match the turbine rotation (rpm) with the target turbine rotation corresponding to the elapsed time from the start of the shift, with the release side command hydraulic pressure Po4 as a basic value.
[0077]
First, the target gear ratio is set according to the elapsed time from the start of the shift (see FIG. 29), and the target turbine rotation is calculated from the target gear ratio and the output shaft rotation (vehicle speed VSP). Then, a feedback correction amount is calculated from the deviation between the actual turbine rotation and the target turbine rotation by, for example, proportional / integral / derivative control (PID control), and the release-side command hydraulic pressure Po4 is corrected by the feedback correction amount. As a result, the gear ratio during the inertia phase can be accurately changed along with the change in the target gear ratio.
[0078]
On the other hand, the inertia phase process on the fastening side is shown in the flowcharts of FIGS.
FIG. 15 shows the main routine of the inertia phase process on the engagement side. In step S61, it is determined whether or not the gear ratio exceeds the engagement start gear ratio (1), and the engagement start gear ratio (1) is determined. Until it exceeds, it progresses to step S62 and performs standby pressure control.
[0079]
The gear ratio is a parameter for determining the progress rate of the shift, and the actual gear ratio is compared with the engagement start gear ratio (1) or the engagement start gear ratio (2), which will be described later. The timing for increasing the side engagement hydraulic pressure is determined.
[0080]
The standby pressure control is shown in the flowchart of FIG. 16, but in step S621, following the standby pressure control in the preparation phase, the engagement side hydraulic pressure is held at the standby pressure Prtn-c.
[0081]
If it is determined in step S61 that the gear ratio has exceeded the engagement start gear ratio (1), whether or not the gear ratio has exceeded the engagement start gear ratio (2) (> engagement start gear ratio (1)) in step S63. Is determined.
[0082]
Then, during the period from when the gear ratio exceeds the engagement start gear ratio (1) until it exceeds the engagement start gear ratio (2), the process proceeds to step S64, and the changeover preparation control is performed as preparation for changeover control in the torque phase. Do.
[0083]
The changeover preparation control is shown in the flowchart of FIG. 17. In step S641, the inertia torque (shift torque) Tinr is set and the inertia torque Tinr is corrected according to the vehicle speed in the same manner as in steps S511 and S512. The oil pressure equivalent to the inertia torque is calculated as follows.
[0084]
Inner shuttle equivalent hydraulic pressure = Tr-o x Tinr x HOSEI- _VSP × K1 + Prtn-c
Here, Prtn-c is the standby pressure on the fastening side.
[0085]
In step S642, the engagement starts from the engagement start gear ratio (1) while changing from the engagement start gear ratio (1) to the engagement start gear ratio (2) (depending on the amount of gear ratio change per unit time obtained from the target shift time). In the time period during which the gear ratio (2) changes, the standby pressure Prtn-c is increased to the inertia equivalent hydraulic pressure (see FIG. 30).
[0086]
During the inertia phase, when determining the transmission torque capacity of the frictional engagement element on the disengagement side, the transmission torque capacity is corrected to decrease by an amount corresponding to the negative inertia torque, so that the gear ratio change ends and the negative inertia When the torque is no longer generated, the torque cannot be transmitted with the transmission torque capacity of the disengagement side frictional engagement element. Therefore, the transfer torque capacity of the engagement side frictional engagement element is increased in advance by an amount corresponding to the torque increase corresponding to the inertia torque, so that the release side frictional engagement element is changed to the engagement side frictional engagement element. It is possible to prevent the entire transmission torque capacity from being insufficient in the initial state of switching.
[0087]
If the engagement start gear ratio (2) (first predetermined value) is exceeded, the process proceeds to step S66 when the predetermined time TIMER3 determined in step S65 is reached, and the switching control is executed.
[0088]
The release of the friction engagement element on the release side (for the high speed stage) is started from the end of the shift (after the gear ratio becomes the value after the shift), as will be described later, whereas the release on the engagement side (low speed) The reason why the changeover preparation control and the changeover control of the friction engagement element for the stage are executed from the time when the gear ratio is changed is because the change in the actual transmission torque capacity (engagement hydraulic pressure) is delayed with respect to the hydraulic pressure command. As described above, if the changeover preparation control and the changeover control of the friction engagement element on the engagement side (for the low speed stage) are started prior to the release control, when the gear ratio reaches the value after the shift. Even if the release control of the friction engagement element for the high speed stage is started, no racing occurs due to a delay in engagement, and the release operation can be started immediately from the end of the shift.
[0089]
The switching control is shown in the flowchart of FIG. 18, and in step S661, the setting of the ramp Rmp-Tr (1) for increasing the engagement-side hydraulic pressure (torque sharing ratio) with time is shown in FIG. As described above, a search is made from a table stored in advance according to the elapsed time from exceeding the engagement start gear ratio (2). The ramp Rmp-Tr (1) is 0 when the engagement start gear ratio (2) is exceeded, and rises at a constant rate with time so that it becomes 1 when the predetermined time TIMER3 is reached. It is like that.
[0090]
In step S662, the engagement side command pressure Pc1 is calculated from the ramp Rmp-Tr (1), the inertia torque Tinr, the estimated input torque Tt, and the like according to the following equation.
Pc1 = K2 × Tt × Tr-c × Rmp-Tr (1) + Tr-o × Tinr × HOSEI- _VSP × K1 + Prtn-c
Here, K2 is a conversion coefficient for converting the transmission torque capacity on the engagement side to hydraulic pressure, Tt is the estimated input torque, and Tr-c is a critical torque ratio set for each friction engagement element on the engagement side. The minimum hydraulic pressure (critical transmission torque capacity) on the fastening side capable of transmitting the input torque at that time is obtained by × Tt × Tr-c.
[0091]
The ramp Rmp-Tr (1) is initially 0 and rises to 1 after a predetermined time TIMER3 has elapsed, so K2 × Tt × Tr-c × Rmp-Tr (1) is initially 0 and after the predetermined time TIMER3 has elapsed. K2 × Tt × Tr-c. Tr-o x Tinr x HOSEI- _VSP XK1 + Prtn-c is the inertia torque corresponding to the inertia torque, and the inertia torque corresponding to the initial torque is K2 × Tt × Tr-c within the predetermined time TIMER3. The hydraulic pressure is increased and changed to an engagement hydraulic pressure that can transmit the input shaft torque with only the combination element.
[0092]
As will be described later, the release-side hydraulic pressure is decreased in response to the increase of the engagement-side hydraulic pressure within the predetermined time TIMER3, and the torque from the release-side friction engagement element to the engagement-side friction engagement element is reduced. A change is made.
[0093]
When the gear ratio exceeds the F / B end gear ratio, the process proceeds from step S4 to step S6 in the flowchart of FIG. 5, a predetermined time TIMER4 elapses after the F / B end gear ratio is exceeded, and the predetermined time It is determined whether or not a predetermined time TIMER5 has elapsed since the time TIMER3 passed. And when either one has not passed, it progresses to Step S7 and performs torque phase processing.
[0094]
The torque phase process on the release side is shown in the flowchart of FIG. 19, and in step S701, ramp control is performed to reduce the release side hydraulic pressure to 0 in the predetermined time TIMER4.
[0095]
Specifically, from the release-side hydraulic pressure Po5 when the gear ratio exceeds the F / B end gear ratio (second predetermined value) and the predetermined time TIMER4, the hydraulic pressure decrease gradient Rmp-Po3 is calculated as follows:
Rmp-Po3 = (Po5-0) / TIMER4
And the hydraulic pressure is decreased by Rmp-Po3 per unit time.
[0096]
The predetermined times TIMER3, TIMER4, and TIMER5 are set for each type of shift and each friction engagement element.
On the other hand, the torque phase process on the fastening side is shown in the flowcharts of FIGS.
[0097]
The flowchart of FIG. 20 shows the main routine of torque phase processing on the engagement side. In step S81, it is determined whether or not a predetermined time TIMER3 has elapsed after the gear ratio exceeds the engagement start gear ratio (2). To do.
[0098]
If the predetermined time TIMER3 has not elapsed, the process proceeds to step S82, and the switching control is continued following the process in the inertia phase.
The contents of the switching control are shown in steps S821 and S822 in the flowchart of FIG. 21, but detailed description thereof is omitted because the same processing as in FIG. 18 is performed.
[0099]
If it is determined in step S81 that the predetermined time TIMER3 has elapsed, the process proceeds to step S83, and it is determined whether or not the predetermined time TIMER5 has further elapsed since the predetermined time TIMER3 has elapsed.
[0100]
And if it is in the said predetermined time TIMER5, it will progress to step S84 and will perform shelf pressure control.
The shelf pressure control is shown in the flowchart of FIG. 22. In step S841, the torque sharing ratio of the engagement-side frictional engagement element after the shift is set, and in the next step S842, the engagement-side command pressure is determined according to the following equation. Pc2 is calculated.
[0101]
Pc2 = K2 x Tt x Tr-c + Tr-o x Tinr x HOSEI- _VSP × K1 + Prtn-c
When the predetermined time TIMER4 elapses after exceeding the F / B end gear ratio, and when the predetermined time TIMER5 further elapses from the time when the predetermined time TIMER3 elapses, the process proceeds from step S6 to step S7 in the flowchart of FIG. It is determined whether or not a predetermined time TIMER6 set in accordance with the type of shift and the friction engagement element has elapsed since the predetermined time TIMER5 has elapsed.
[0102]
If the predetermined time TIMER6 has not elapsed, the end phase process of step S9 is executed.
The release-side end phase process is shown in the flowchart of FIG. 23. In step S901, the release-side hydraulic pressure (= 0) at the end of the torque phase is held.
[0103]
On the other hand, end phase processing on the fastening side is shown in the flowcharts of FIGS.
The flowchart of FIG. 24 shows the main routine of the end phase process on the engagement side. If it is determined in step S91 that the predetermined time TIMER6 has not elapsed since the transition to the end phase process, the process proceeds to step S92 and the engagement is performed. The end phase processing on the side is executed.
[0104]
The content of the engagement-side end phase process is shown in the flowchart of FIG. 25. In step S921, the transmission torque capacity of the engagement-side friction engagement element is set from the value (critical pressure) at the end of the torque phase to the predetermined time. For example, the ramp Rmp-Tr (2) is increased by TIMER6 to 1.2 times (see FIG. 32).
[0105]
In step S922, the command pressure on the engagement side is calculated according to the following equation based on the lamp Rmp-Tr (2).
Pc3 = K2 * Tt * Tr-c * (1 + 0.2 * Rmp-Tr (2)) + Tr-o * Tinr * HOSEI- _VSP × K1 + Prtn-c
In the predetermined time TIMER6, the pressure is increased to about 1.2 times the critical pressure by controlling to the command pressure Pc3 calculated by the above formula, but when the predetermined time TIMER6 has elapsed, the hydraulic pressure is stepped up to the maximum pressure. Increase.
[0106]
It is obvious that the speed change mechanism is not limited to that shown in FIG.
[Brief description of the drawings]
FIG. 1 is a diagram showing a transmission mechanism of an automatic transmission according to an embodiment.
FIG. 2 is a diagram showing a correlation between a combination of engagement states of friction engagement elements in the speed change mechanism and a gear position;
FIG. 3 is a system diagram showing a control system of the automatic transmission.
FIG. 4 is a time chart showing a state of shifting by changing friction engagement elements in the embodiment.
FIG. 5 is a flowchart showing a state of switching shift control of the friction engagement element in the embodiment.
FIG. 6 is a flowchart showing preparation phase processing for a release-side frictional engagement element.
FIG. 7 is a flowchart showing preparation phase processing for a release-side frictional engagement element.
FIG. 8 is a flowchart showing preparation phase processing of a release side frictional engagement element.
FIG. 9 is a flowchart showing a preparatory phase process for the engagement side frictional engagement element.
FIG. 10 is a flowchart showing a preparation phase process of a fastening side frictional engagement element.
FIG. 11 is a flowchart showing a preparation phase process of the engagement side frictional engagement element.
FIG. 12 is a flowchart showing inertia phase processing of a release side frictional engagement element.
FIG. 13 is a flowchart showing inertia phase processing of a release side frictional engagement element.
FIG. 14 is a flowchart showing inertia phase processing of a disengagement side frictional engagement element.
FIG. 15 is a flowchart showing inertia phase processing of the engagement-side frictional engagement element.
FIG. 16 is a flowchart showing inertia phase processing of the engagement side frictional engagement element.
FIG. 17 is a flowchart showing inertia phase processing of the engagement side frictional engagement element.
FIG. 18 is a flowchart showing inertia phase processing of the engagement side frictional engagement element.
FIG. 19 is a flowchart showing torque phase processing of the release side frictional engagement element.
FIG. 20 is a flowchart showing torque phase processing of the engagement side frictional engagement element.
FIG. 21 is a flowchart showing torque phase processing of the engagement side frictional engagement element.
FIG. 22 is a flowchart showing torque phase processing of the engagement side frictional engagement element.
FIG. 23 is a flowchart showing end phase processing of a disengagement side frictional engagement element.
FIG. 24 is a flowchart showing an end phase process of the engagement-side frictional engagement element.
FIG. 25 is a flowchart showing end phase processing of the engagement side frictional engagement element.
FIG. 26 is a diagram showing a change in margin in the sharing ratio ramp control of the disengagement side frictional engagement element.
FIG. 27 is a diagram showing a correlation between a shift time and a shift torque (inner torque).
FIG. 28 is a diagram showing a correction coefficient according to the vehicle speed of the transmission torque (inner torque).
FIG. 29 is a diagram showing a correlation between a target shift time and a target gear ratio.
FIG. 30 is a diagram showing the characteristic of the indicated pressure in the changeover preparation control of the engagement-side frictional engagement element.
FIG. 31 is a diagram showing a hydraulic gradient characteristic in the switching control of the engagement side frictional engagement element.
FIG. 32 is a diagram showing a characteristic of a hydraulic pressure gradient in an end phase process of the engagement side frictional engagement element.
[Explanation of symbols]
1 ... Torque converter
2 ... Transmission mechanism
11 ... Solenoid valve unit
12 ... A / T controller
13 ... A / T oil temperature sensor
14 ... accelerator opening sensor
15 ... Vehicle speed sensor
16 ... Turbine rotation sensor
17 ... Engine rotation sensor
18 ... Air flow meter
20 ... Engine
G1, G2 ... Planetary gear
H / C ... High clutch
R / C ... Reverse clutch
L / C ... Low clutch
2 & 4 / B ... 2 speed / 4 speed band brake
L & R / B ... Low & Reverse Brake

Claims (2)

In a shift control device for an automatic transmission configured to perform a downshift by changing over a friction engagement element that fastens a friction engagement element for low speed stage while releasing a friction engagement element for high speed stage,
With the engagement hydraulic pressure of the low-speed stage friction engagement element held at the standby pressure, the engagement hydraulic pressure of the high-speed stage friction engagement element is decreased, and the gear ratio (= input shaft rotation speed / output shaft rotation speed). ) Becomes the feedback start gear ratio, feedback control for correcting the engagement hydraulic pressure of the high-speed stage friction engagement element is started in order to match the actual input shaft rotation speed with the target input shaft rotation speed,
The engagement hydraulic pressure of the low-speed stage friction engagement element is equivalent to the inertia torque from the standby pressure until the second engagement start gear ratio is larger than the first engagement start gear ratio that is larger than the feedback start gear ratio. Up to pressure,
The engagement hydraulic pressure of the low-speed stage friction engagement element is calculated from the inertia torque equivalent pressure and the input shaft torque at that time is the low-speed stage friction in the first predetermined time after the second engagement start gear ratio is reached. Increasing change to hydraulic pressure that can be transmitted only with the engagement element,
The feedback control is terminated when the feedback end gear ratio is larger than the second engagement start gear ratio, and then the engagement hydraulic pressure of the high-speed stage friction engagement element is reduced to 0 in a second predetermined time. A shift control device for an automatic transmission, characterized in that The first predetermined time for increasing the engagement hydraulic pressure of the low-speed stage frictional engagement element and the second predetermined time for decreasing the engagement hydraulic pressure of the high-speed stage frictional engagement element are defined as the type of shift and / or 2. The shift control device for an automatic transmission according to claim 1, wherein the shift control device is changed according to the type of the friction engagement element.

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