JPH0495658A - Line pressure control device for automatic transmission - Google Patents

Abstract

PURPOSE:To previously prevent the wrong learning control for line pressure due to splip-off speed change from transmission oil pressure by providing a second correction means correcting the line pressure toward a rise direction responding to judging when a measured time is judged longer than a given value. CONSTITUTION:A control unit 100 has a control means 103 controlling the line pressure of a hydraulic control circuit 30 by controlling the duty solenoid valve 33 of a line pressure variable means, and a first learning correction means 104 detecting a speed change time based on the variation condition of a turbine engine speed at the time of a speed change and learning-correcting the line pressure so that the speed change time can become a target value. In addition to these means 103 and 104, the following means are provided: a timing means 105 measuring a time from the point of the time of transmitting a speed change command signal to the point of the time of the change start of a turbine engine speed, and a second correction means 107 correcting the line pressure toward a rise direction responding to judging when a measured time is judged longer than a given value with a comparing means 106 comparing a measured time measured with the timing means 105 to a given value previously set.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a line pressure control device for an automatic transmission, and particularly to learning control of line pressure during gear shifting.

(Prior Art) Automobile automatic transmissions generally include a torque converter and a multi-stage transmission mechanism using a planetary gear mechanism, etc., and various clutches for switching the power transmission path in the transmission mechanism.
Frictional elements for speed change such as brakes are provided, and these frictional elements are operated by a hydraulic control circuit.

Then, by controlling a solenoid valve or the like incorporated in the hydraulic control circuit, the friction elements are engaged and opened, and the gears are changed.

The line pressure of the hydraulic control circuit is maintained by an oil pump and a pressure regulating valve, but if the line pressure is too high during gear shifting, the friction elements are suddenly engaged, causing a gear shifting shock, and if the line pressure is too low, , the shift time becomes longer, and the friction elements become abnormally worn and generate heat.

For this reason, for example, in the device disclosed in Japanese Patent Publication No. 63-3183, the line pressure supplied to the friction element is controlled so that the engagement force of the friction element changes gradually during a gear shift, and the gear change time (shift time ) by setting a target value in advance and feedback-controlling the line pressure according to the difference between this target value and the actual shift time.
Adjustment is made so that the actual shift time approaches the target value above. Recently, it has been proposed to optimize the switching timing of the friction elements by learning and correcting the line pressure so that the shifting time during shifting becomes a target value.

When performing line pressure learning control as described above, the shift time is detected based on the change in the input speed of the transmission, such as the turbine speed of the torque converter or the engine speed during a speed change, and this shift time is determined based on the target speed. The line pressure is learned and corrected to match the value.

FIG. 18 is a timing chart showing a conventional line pressure correction method based on learning of shift time.

As shown in FIG. 18(a), while traveling at an arbitrary n-th speed,
Assume that a command signal to shift up to the (n+1)th speed is issued at time t1. Here, the line pressure control signal, which is proportional to the line pressure level, falls from A to B from time t1 to time t4, as shown by the solid line in FIG. 18(b), and the line pressure also decreases accordingly. In addition, the shift hydraulic pressure is controlled by the "tank pressure" shown by the solid line in Fig. 18 (c) due to the action of an accumulator provided in the hydraulic control circuit.
A zone H in which the oil pressure gradually increases is formed, and a shift is performed within this tank pressure zone H. That is, as shown by the solid line in FIG. 18(d), the turbine rotational speed NT starts to decrease from time t2, and starts to increase from time t3.

The period T from this time point t2 to t3 becomes the actual shift time detected by the computer. During this time, the torque G of the transmission output shaft changes as shown by the solid line in FIG. 18(e).

Here, the actual shift time T is measured and compared with the preset target value T0. If T is less than To, a positive time difference T is detected.
, -T is determined, and the line pressure control signal is learned and corrected to B' = B - α as shown by the broken line B' in Fig. 18 (b), and the previous learning is performed. Update the value. As the line pressure decreases due to the correction of the line pressure control signal, the tank pressure decreases to H' as shown by the broken line in FIG.
', and the shift time T' becomes longer as shown in FIGS. 18(d) and (e).

On the other hand, if the actual shift time T is longer than the target value T0,
A correction value α of the line pressure control signal is determined according to the negative time difference T−T, and the line pressure control signal is learned and corrected to B′=B+α, and the previous learned value is updated. As the line pressure increases due to the correction of the line pressure control signal, the tank pressure also increases, and the shift time becomes shorter.

By the way, when the transmission mechanism is new, the frictional resistance μ of various clutches, brakes, and other transmission friction elements is low. In such a case, although the tank pressure is normally established as shown by the solid line in FIG. 19(c), the turbine rotational speed is low at the normal shift start time t2, as shown by the solid line in FIG. 19(d). N, hardly changes, and the upward slope becomes only slightly slow, and the time point at which the turbine rotational speed N1 starts to decrease is, for example, time t3 near the end time t4 of the tank pressure portion H.
I will be late. Therefore, the shift ends at time t5 after the shift oil pressure has risen to the final pressure (off-shelf shifting), and since the shift is performed with the shift oil pressure increased to the final pressure, from time t3 to time The shift time T up to t5 is extremely short, and as a result, as shown in Fig. 19 (
As shown by the solid line in (e), a large torque fluctuation occurs on the transmission output shaft, which causes an unpleasant shift shock.

Furthermore, in this case, although the entire time during which gear shifting is actually performed is a relatively long time T2 from time t2 to time t5, the actual gear shifting time that can be detected by the computer is
Since it is a short time T from the time t3 when the turbine rotational speed NT starts to decrease to the time t5 when it changes from decreasing to increasing, it is determined that T < To, and as in the case of Fig. 18, The line pressure control signal is corrected to B-α as shown by the broken line in Fig. 19 (b), and along with this, the tank pressure also decreases as shown by the broken line in Fig. 19 (c), so the shift time As a result, as shown by the broken lines in FIGS. 19(d) and (e), the out-of-shelf shifting is further increased. Therefore, there arises the disadvantage that the shift shock increases.

(Object of the Invention) Therefore, the present invention provides a correction means that detects the shift time based on the changing state of the rotation speed on the input side of the transmission, and learns and corrects the line pressure so that the shift time becomes a target value. To provide a line pressure control device for an automatic transmission which prevents occurrence of off-shelf shifting and prevents erroneous learning control based on off-shelf shifting from being performed. With the goal.

(Structure of the Invention) The line pressure control means for an automatic transmission according to the present invention includes a timer for measuring the time from the time when a shift signal is issued to the time when the rotation speed on the input side of the transmission starts changing; a comparison means for comparing the measured time with a predetermined value set in advance; and if the comparison means determines that the measured time is longer than the predetermined value, the line pressure is increased in response to the comparison means; and second correction means for correcting in the upward direction.

(Effects of the Invention) According to the present invention, if the time from the time when the gear change command signal is issued to the time when the transmission input side rotation speed starts changing, the transmission input side rotation speed becomes longer than a predetermined value. Since the line pressure is corrected in the upward direction regardless of the length of time from the start of the change to the end of the change, this causes the tank pressure to rise, and even if the friction coefficient of the friction element is low, the tank pressure always increases. Shifting can be completed within the pressure range.

Therefore, it is possible to prevent erroneous learning control of the line pressure from being performed due to a gear change due to a drop in tank pressure.

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

FIG. 1 shows the overall configuration of an embodiment of the present invention, and in the figure, an automatic transmission AT includes a torque converter 2, a multi-stage transmission mechanism 10, and a hydraulic control circuit 30. The multi-stage transmission mechanism 10 includes various friction elements (brakes, clutches) for switching power transmission paths, and a hydraulic control circuit 30 controls the engagement and release of each friction element.
It is now controlled by. Inside the hydraulic control circuit 30, there is a pressure regulator valve 32 that adjusts the line pressure that becomes the hydraulic pressure supplied to the friction elements;
Duty solenoid valve 3 that controls this
3, and these valves 32 and 33 constitute a line pressure variable mechanism.

The hydraulic control circuit 30 is a control unit (E CTJ) configured by a microcomputer, etc.
100, this control unit 1
00 includes a signal from a throttle opening sensor 101 that detects the opening of a throttle valve disposed in the intake passage of the engine, a signal from a turbine rotation speed sensor 102 that detects the turbine rotation speed of the torque converter 2, etc. It has been entered.

The control unit 100 includes a control means 103 that controls the line pressure of the hydraulic control circuit 30 by controlling the duty solenoid valve 33 of the line pressure variable means.
In addition to the first learning correction means 104 which detects the shift time based on the state of change in the turbine rotational speed during the shift and learns and corrects the line pressure so that the shift time becomes the target value, the shift command signal time measuring means 10 for measuring the time from the time when the is issued to the time when the turbine rotation speed starts changing;
5, and a comparison means 106 for comparing the measured time measured by the time measurement means 105 with a predetermined value set in advance;
When the comparison means 106 determines that the measured time is longer than the predetermined value, a second correction means 107 is provided which corrects the line pressure in an upward direction in response.

FIG. 2 is a diagram showing an example of the configuration of an automatic transmission AT to which the device of the present invention is applied. In FIG. 2, a torque converter 2 is connected to an output shaft 1 of an engine, and a multi-stage transmission mechanism 10 is disposed on the output side of the torque converter 2. The torque converter 2 is connected to the output shaft 1 of the engine.
A pump 3 fixed to a turbine 4, a fixed shaft 7 via a one-way clutch 6 (fixed to a case 11)
and a stator 5 provided above.

The multi-stage transmission mechanism 10 includes a solid shaft 12 for driving an oil pump whose base end is connected to an oil pump 31, and a turbine 4 whose base end is a torque converter 2 outside the solid shaft 12. a hollow turbine shaft 13 connected to
A Ravigneau-type planetary gear unit 14 is provided on the turbine shaft 13. This planetary gear device 14
consists of a small-diameter sun gear 15, a large-diameter sun gear 16, a long pinion gear 17, a short pinion gear 18, and a ring gear 19, and the following various friction elements are incorporated into this planetary gear device 14.

A forward clutch 20 and a coast clutch 21 are arranged in parallel between the turbine shaft 13 and the small diameter sun gear 15 at the end farthest from the engine. The forward clutch 20 is a first one-way clutch 22
It connects and disconnects power transmission from the turbine shaft 13 to the small diameter sun gear 15 via
is for intermittent power transmission between the turbine shaft 13 and the small diameter sun gear 15.

A 2-4 brake 23 having a brake drum 23a connected to the large-diameter sun gear 16 and a brake band 23b hooked to the brake drum 23a is arranged radially outward of the coast clutch 21. −
When the four brakes 23 are engaged, the large diameter sun gear 16 is fixed. Behind the 2-4 brake 23 (on the right side of the figure), a reverse clutch 24 for backward running is arranged to intermittent power transmission between the large-diameter sun gear 16 and the turbine shaft 13 via the brake drum 23a. has been done. Further, on the radially outer side of the planetary gear device 14, the carrier 14a of the planetary gear device 14 and the speed change gear mechanism 1
A low reverse brake 25 for engaging and disengaging the carrier 14a and the case 10a is disposed between the carrier 14a and the case 14a, and a second one-way clutch 26 is disposed in parallel thereto.

Further, a 3-4 clutch 27 is disposed at the end of the planetary gear set 14 on the engine side to connect and disconnect power transmission between the carrier 14a and the turbine shaft 13. Further, an output gear 28 connected to the ring gear 19 is arranged in front of the 3-4 clutch 27 (on the left side in the figure), and this gear 28 is attached to an output shaft 28a. Note that 29 is a lock-up clutch for directly connecting the output shaft 1 of the engine and the turbine shaft 13 without using the torque converter 2.

This transmission gear mechanism 10 has four forward speeds and one reverse speed.
It has several gears, and a desired gear can be obtained by appropriately operating the clutches 20, 21, 24, 27 and brakes 23, 25. Here, Table 1 shows the operational relationship between each gear stage, clutch, and brake.

FIG. 3 shows the hydraulic control circuit 3 in the automatic transmission AT.
It shows 0. This hydraulic control circuit 30 has an oil pump 31 driven by the engine output shaft 1, and hydraulic oil is discharged from the pump 31 into the oil path L1. The hydraulic oil discharged from the pump 31 to the oil path L1 is guided to the pressure regulator valve 32. This pressure regulator valve 32 adjusts the oil pressure (line pressure) of hydraulic oil from the pump 31 and is controlled by a duty solenoid valve 33. That is, the hydraulic pressure of the hydraulic oil reduced to a predetermined pressure by the solenoid reducing valve 34 is duty-controlled by the duty solenoid valve 33. In other words, the hydraulic pressure is controlled by adjusting the opening/closing time ratio of the duty solenoid valve 33 to control the drain amount, and this is given as a pilot pressure to the pressure regulator valve 32, so that the line pressure is adjusted according to this pilot pressure. is adjusted. In this way, the line pressure variable means is configured,
As shown in Figure 1, the duty solenoid valve 3
3 is controlled by the control unit 100, thereby controlling the line pressure.

The line pressure regulated by the pressure regulator valve 32 is transferred to the manual shift valve (select valve) 3.
5 to port g. This manual shift valve 35 is manually shifted to P, R-N-D, 2, and Lunge, and hydraulic oil is supplied from port g to a predetermined port in each range. Port g communicates with port a1e when the manual shift valve 35 is set to range, and communicates with ports a and C when it is set to range 2.
When connected to port a and set to D range, port a,
bSc, and when set to R range, communicates with ports e and f.

Port a of the manual shift valve 35 is connected to the 1-2 shift valve 36 through an oil passage L2. A pilot pressure controlled by a 1-2 solenoid valve 37 acts on the 1-2 shift valve 36 . In the first gear, the 1-2 solenoid valve 37 is turned off, so that the spool of the 1-2 shift valve 36 is operated, for example, to the left, and the oil passage leading to the apply chamber 23c of the 2-4 brake 23 is activated. L3 is communicated with the drain side, and when the 1-2 solenoid valve 37 is turned on in the 2nd-4th gear, the spool of the 1-2 shift valve 36 is operated, for example, to the right, and the hydraulic pressure from port a is is supplied to the apply chamber 23c of the 2-4 brake 23. Furthermore, this 1-2 shift valve 36 is adapted to supply hydraulic oil supplied from port e of the manual shift valve 35 via the low pressure reducing valve 38 to the low reverse brake 25 when the lunge is in the first gear. There is.

The oil pressure from port a of the manual shift valve 35 is 2
-3 shift valve 39 is also given as pilot pressure. This 2-3 shift valve 39 is connected to port C of the manual shift valve 35 through an oil path L4, and its pilot pressure is controlled by a 2-3 solenoid valve 40. And in 1st and 2nd gear, 2
-3 solenoid valve 40 is turned on,
For example, the spool of the 2-3 shift valve 39 is operated to the right, and in this state, the oil passage L leading to the 3-4 clutch 27
5 is communicated with the drain side, and the 3-4 clutch 27 is released. In addition, when the 2-3 solenoid valve 40 is turned off in the third and fourth speeds, the spool of the 2-3 shift valve 39 is operated, for example, to the left, and in this state, the hydraulic oil from port C is 3-4 sent to oil path L5
Clutch 27 is engaged.

The oil passage L5 is also connected to a 3-4 shift valve 41, and a pilot pressure controlled by a 3-4 solenoid valve 42 acts on this 3-4 shift valve 41. When the 3-4 solenoid valve 42 is turned on during the 1st, 2nd, and 4th speeds of the D range and the 1st speed of the 2nd range, the spool of the 3-4 shift valve 41 is moved, for example, to the right. In this state, the oil passage L leading to the release chamber 23d of the 2-4 brake 23 is activated.
6 is connected to the drain side. Also, in 3rd gear of D range,
When the 3-4 solenoid valve 42 is turned OFF during the 2nd and 3rd speeds of the 2 range and the 1st and 2nd speeds of the lunge, the spool of the 3-4 shift valve 41 is operated to the left, for example. In this state, the oil passage L6 and the oil passage L5 connected to the 2-3 shift valve 39 are communicated, and the 2-3 shift valve 39 is connected to the oil passage L6.
-2-4 brake 2 depending on the operation of the -3 shift valve 39
Hydraulic pressure is supplied to and discharged from the release chamber 23d of No. 3. Furthermore, the 3-4 shift valve 41 switches the supply and discharge of hydraulic pressure between the oil passage L7 leading to port a of the manual shift valve 35 and the oil passage L8 leading to the coast clutch 21, thereby controlling the coast clutch 21 accordingly. There will also be a release and a contract.

In this way, in response to the operation of each shift valve 36, 39, 41 controlled by the solenoid valve 37, 40, 42, the 2-4 brake 23, which is a friction element for shifting,
(Hydraulic pressure is supplied to the apply chamber 23c, and the release chamber 23c is
d is engaged when the hydraulic pressure is drained, and otherwise released), and the engagement and release of the clutch 34 is the same as the above-mentioned first
This is done as shown in the table. In addition, each shift valve 36
．． 39. In the hydraulic circuit between 41 and 2-4 brake 23 and 3-4 clutch 27, 1-2 accumulator 43 and 2-3 accumulator 4 are installed to reduce shift shock.
4.2-3 timing valve 45.3-2 timing valve 46 and bypass valve 47 are incorporated.

In addition, the hydraulic control circuit 30 includes D12, an oil passage L9 that sends hydraulic pressure from port a to engage the forward clutch 20 at lunge, and an N-D connected thereto.
Accumulator 48, reverse clutch 24 in R range
Oil line LI that sends hydraulic pressure from port f to tighten
O, an N-R accumulator 49 connected thereto, a lock-up control valve 50 that controls the lock-up clutch 29, a lock-up solenoid valve 51 that controls this, and a converter relief valve 52.
etc. are provided.

For such a hydraulic control circuit 30, the control unit 100 shown in FIG. 1 controls the line pressure according to the flowchart shown in FIG. 4, and this control operation will be described next.

FIG. 4 shows the main routine of line pressure control executed by the control unit 100. First, check whether it is time to shift using Stella 7'S1, and if the determination is No,
In step S2, a routine for line pressure control outside of gear shifting shown in FIG. 9, which will be described later, is executed.

Further, if the determination in step S1 is YES, step S
At step 3, a line pressure control routine during gear shifting shown in FIG. 10, which will be described later, is executed. Then, in step S4, it is determined whether or not there is an upshift, that is, whether a shift command signal from the nth speed to the (n+1)th speed has been issued, as shown in FIG. 5(a). If the determination in step S4 is YES, step S5
, S6 reads the throttle opening TVO and turbine rotational speed N□, and in step S7 the line pressure control signal is lowered from A to B as shown by the solid line in FIG. Start counting. This timer counter I is measured at the time t when the shift command signal is issued.
This means measures the time T1 from 1 to the time t3 when the turbine rotational speed N7 starts changing, and corresponds to the time measuring means 105 in FIG. Therefore, in step S9, the current turbine rotation speed N Ta + 1 is changed to the previous turbine rotation speed N7. ,
In this step S9, check whether it has become smaller than
At time t3 when the determination becomes YES, the process advances to step S10, where the timer counter I finishes counting, and at the next step Sll, the timer counter 2 starts counting. As shown in FIG. 5(d), this timer counter (2) is a counter that measures the time T from the time t3 when the turbine rotational speed NT starts to decrease to the time t5 when it changes from decreasing to increasing. Therefore, in step S12, the current turbine rotation speed N T+++1 is changed from the previous turbine rotation speed N
,. , and at time t5 when the determination in step S12 becomes YES, step S13 is performed.
Proceed to and end the count of the timer counter ■.

Next, in step S14, the time T1 from time t1 to t3 measured by the timer counter I is set to T1. In comparison, when T1≧T1°, the process advances to step S15, and as a process corresponding to the second correction means 107 shown in FIG. By doing so, the line pressure is increased as shown by the broken line in FIG. 5(B), and thereby the tank pressure is increased as shown by the broken line in FIG. 5(C). On the other hand, step S14
When it is determined that Tl<To, the process advances to step S16, and as a process corresponding to the first correction means 104 shown in FIG. Run the pressure correction routine to correct line pressure.

Note that the line pressure control signal levels A and B are changed according to the throttle opening TVO as shown in FIG.
A preset predetermined value T1° is compared with the time T1 from t3 to t3, and a preset predetermined value T is compared with the shift time T from time t3 to t5. Also, Figures 7 and 8
As shown in the figure, it is changed according to the throttle opening TVO. In addition, the line pressure control signal level ASB and the predetermined values T1o and T0 vary depending on the type of upshift of the transmission, that is, from 1st gear to 2nd gear, from 2nd gear to 3rd gear, and from 3rd gear to 3rd gear. It also changes depending on which of the four speeds it is in.

The routine for line pressure control outside of gear shifting performed in step S2 in FIG. 4 is as shown in FIG.

In this routine, in steps S21 and S22, the throttle opening degree and the turbine rotation speed are measured by each sensor 101.
．． 102, and in step S23, the line pressure is determined by map search according to the throttle opening and the turbine rotation speed. That is, regarding the line pressure when the gear is not shifted, values corresponding to the throttle opening degree and the turbine rotational speed are stored in advance as a map in the memory within the control unit 100, and the values are retrieved.

Next, in accordance with the line pressure determined in step S23, the duty ratio of the duty solenoid valve 33 is determined by executing a duty ratio determination routine to be described later in step S24. Further, in step S25, the solenoid drive frequency is set to, for example, 35 Hz. Next, in step S26, the ON time of the duty solenoid valve 33 in one cycle is determined by multiplying the drive cycle (reciprocal of the drive frequency) by the duty ratio, and in accordance with this, the duty solenoid valve 33 is turned on in step S27. drive Thereby, the line pressure is controlled to the value determined in step S23.

The routine for line pressure control during gear shifting performed in step S3 in FIG. 4 is as shown in FIG. 10. In this routine, first, in step S31, it is determined whether or not there is an upshift. When shifting up, the throttle opening is read in step S32, and the line pressure PL is determined in step S33 according to the shift mode, the gears before and after the shift, and the throttle opening. In this way, the line pressure during upshifting can be adjusted appropriately. In other words, the shock at the time of upshifting is related to the engine output and the gear position depending on the throttle opening, and in particular, the shared torque and capacity of the friction elements that are switched during gear shifting differ depending on the gear position. If the line pressure is set regardless, it is not possible to adjust the optimum speed etc. for all the gears only by setting the characteristics of the accumulator in the hydraulic control circuit 30. Therefore, in this embodiment, regarding the line pressure at the time of upshifting,
As shown in FIG. 11(a), the line pressure values according to the throttle opening degree are stored as a map in the memory in the control unit 100 for each combination of gears before and after shifting, and the line pressure is determined from this map. I have to. Therefore, conventionally, the line pressure is set to be relatively high enough to prevent all the friction elements from slipping, as shown by the two-dot chain line in FIG. 11(b). )
As shown by the solid line in , the line pressure is set to a value that is lower than before and differs depending on the gear position. And this value is
It is corrected and optimized by the routine (step 516) in FIG. 16, which will be described later.

Further, when the determination in step S31 is No, that is, when the shift is down, it is checked in step S34 whether or not the shift is down from the third gear to the second gear, and the determination is YES.
If so, line pressure calculation processing is performed in steps 335 to S38, and if NO, the process moves to line pressure control outside of gear shifting (step S2). This is done because the 3-4 clutch 27 is released when downshifting from 3rd gear to 2nd gear when using a multi-stage transmission mechanism and hydraulic control circuit as shown in Figures 2 and 3. At the same time, the 2-4 brake 23 is engaged, so adjustment of the engagement timing is required. However, during other downshifts, only the 3-4 clutch 27 or 24 brake 23 is released, and the engagement timing is determined by line pressure. This is because no adjustment is required. However, if the multi-stage transmission mechanism and hydraulic control circuit are configured differently from those shown in Figures 2 and 3,
If there is a case where a specific friction element is released and other gear shifting friction elements are engaged during a downshift other than a downshift from a gear to a second gear, the processes of steps 335 to S38 can also be performed during such a gear shift. Bye.

In the process of downshifting from third speed to second speed, the turbine rotation speed is read in step S35, and step S3
In step 6, the baseline pressure PL is determined according to the turbine rotation speed. In other words, from the third speed to the second speed according to this embodiment,
When downshifting to high speed, the 3-4 clutch 27 is released to set the neutral state, and the 2-4 brake 23 is engaged when the turbine rotation speed reaches the appropriate rotation speed, but the engagement timing depends on the turbine rotation speed. Therefore, as shown in Fig. 12, the control unit 1 uses the baseline pressure PL according to the turbine rotation speed as a map.
00, and the baseline pressure PL is determined from this map.

Following step S36, in step S37.338,
The line pressure is corrected according to the throttle opening change rate calculated from multiple throttle opening detection values.In other words, as the throttle opening change rate becomes faster, the engine speed (turbine speed) increases faster. Therefore, in order to advance the engagement timing accordingly, as shown in FIG. 13, a correction coefficient Ca is determined according to the throttle opening change speed, and the final line pressure PL is determined by multiplying the baseline pressure PL0 by this coefficient.

Following step S33 or step S38, a duty ratio determination routine (described later) is executed in step S39, a solenoid drive frequency is set in step S40, a solenoid ON time is calculated in step S41, and a duty ratio is determined in step S42. By driving the solenoid valve 33, the duty solenoid valve 33 is controlled so that the line pressure becomes the value determined in step S33 or step 338. These steps 33
9 to S42, the duty ratio determination routine performed in step S24 in FIG. 9 and step S39 in FIG. 10 is as shown in FIG. In this routine, the line pressure is read in step S45, and the oil temperature of the automatic transmission is read in step S46. Then, in step S47, a base duty ratio D U o is determined in accordance with the line pressure at the oil temperature at that time. In other words, since the correspondence relationship between the duty ratio of the duty solenoid valve 33 and the line pressure changes depending on the oil temperature, as shown in the frame of step S47, the relationship between the duty ratio and line pressure at a plurality of oil temperatures is determined in advance. The correspondence relationships between the two are investigated and stored in the memory as maps, and from these maps, the base duty ratio DU is determined by performing linear interpolation between each temperature. Further, during a predetermined period of time after the engine starts, the characteristics of the control pressure with respect to the duty ratio differ due to the influence of air entrainment. Therefore, in step S48, the elapsed time after the key is turned on is checked, and in step S49, the elapsed time is determined as shown in the figure. A correction coefficient Cdu is determined according to the step S50.
and the above base duty ratio DU, and the above correction coefficient Cdu.
The final duty ratio DU is obtained by multiplying by . In this way, the duty ratio is determined so as to give the calculated line pressure.

At step 814 in FIG.
The line pressure increase correction routine executed in step S15 in FIG. 4 when it is determined that the count value TI is larger than a preset predetermined value T1° is as shown in FIG.

First, in step S51, the difference ΔT1 between the count value T1 of the timer counter I and the predetermined value T1o is calculated, and in the next step S52, a map search is performed for a positive correction value α of the line pressure control signal according to the difference ΔT1, In step S53, the line pressure control signal is corrected to B10α as shown by the broken line in FIG. Make sure to end it within the pressure section. Then, the learned value is updated in step S54.

Next, in step S14 in FIG. 4, learning of the shift time is executed in step S16 in FIG. The line pressure correction routine will be explained below.

First, in step S61, the count value T of the timer counter ■
is a predetermined value T. Check whether it is greater than
If this determination is YES, that is, if the shift time T' is longer than To, as shown by the dashed line in FIG.
In step S62, the count value T and the predetermined value T of the timer counter ■. In the next step S63, a map is searched for the positive correction value α of the line pressure control signal according to the difference T, and in step S64, the line pressure control signal is changed to B+α.
The learned value is updated in step S65. on the other hand,
When the determination in step S61 is No, step S6
Proceeding to step 6, the count value T of the timer counter ■ is the predetermined value T. If the determination is YES, that is, if the shift time T' is shorter than To, as shown by the broken line in FIG. 17, the count value T of the timer counter The difference ΔT from the predetermined value T0 is determined, and in the next step S68, a negative correction value α of the line pressure control signal corresponding to the difference ΔT is searched on the map, and the process is performed in step S68.
In step S69, the line pressure control signal is corrected to B-α to lower the line pressure, and in step S65, the learned value is updated.

As is clear from the above description, in the line pressure control device for an automatic transmission according to the present embodiment, the timer counter I counts the time from when a shift command signal is issued until the turbine rotation speed starts to change. The value T1 is the predetermined value T
1. When it is larger than , the line pressure is corrected in the upward direction regardless of the count value of the timer counter ■, so the tank pressure increases, and even if the friction coefficient of the friction element is low, the line pressure is corrected in the upward direction. As shown by broken lines in Figures (D) and (C), the shift can always be completed within the tank pressure section. Therefore, it is possible to prevent the line pressure from being erroneously learned and corrected due to the shift change due to the drop in tank pressure.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, Fig. 2 is a schematic diagram of the structure of an automatic transmission, Fig. 3 is a block diagram of a hydraulic control circuit for the transmission mechanism, and Fig. 4 is a block diagram showing the overall configuration of an embodiment of the present invention. Flowchart showing the main routine of line pressure control, FIG. 5 is a timing chart for explaining line pressure correction in the device of the present invention, FIG. 6 is a characteristic diagram of line pressure control signal according to throttle opening, and FIG. 7 , FIG. 8 is a characteristic diagram of the setting time according to the throttle opening degree, FIG. 9 is a flowchart showing the line pressure control routine outside of gear shifting, and FIG.
Fig. 0 is a flowchart showing the line pressure control routine during gear shifting, Figs.
Figure 2 is a chart showing a map of the baseline pressure during downshifting, Figure 13 is a characteristic diagram of the correction coefficient according to the rate of change in throttle opening, Figure 14 is a flowchart showing the duty ratio determination routine, and Figure 15. is a flowchart showing a line pressure increase correction routine, FIG. 16 is a flowchart showing a line pressure correction routine by learning shift time, FIG. 17 is a diagram showing changes in turbine rotation speed during upshifting, and FIGS. 18 and 19. is a flowchart for explaining line pressure correction in a conventional line pressure control device. 10... Multi-stage transmission mechanism 30... Hydraulic control circuit 3
2... Pressure regulator pulp 33... Duty solenoid valve 100... Control unit 103... Control means 104... First correction means 105... Timing means 106... Comparison means 107...・Second correction means Kaoru 1m]

Claims (1)

[Scope of Claims] A line pressure variable means capable of changing the line pressure of a hydraulic control circuit for a friction element included in a multi-stage transmission mechanism, a control means for controlling the line pressure variable means, and a transmission input during gear shifting. A line pressure control device for an automatic transmission, comprising: a first correction means that detects a shift time based on a change state of a side rotational speed, and learns and corrects the line pressure so that the shift time becomes a target value. , a timing means for measuring the time from the time when the shift command signal is issued to the time when the speed change on the input side of the transmission starts changing; and comparing the measured time measured by the timing means with a predetermined value set in advance. Comparing means; and second correcting means for correcting the line pressure in an upward direction when the measuring time is determined to be longer than the predetermined value by the comparing means. An automatic transmission line pressure control device featuring: