JPH08334170A - Speed change transition hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE: To precisely detect a transient state at which a speed change stage is changed over by providing a feedback control starting point judging means to judge a starting point of feedback in a speed change transient period based on an effective gear ratio. CONSTITUTION: In the case when it is judged not to be in the middle of speed change, a line pressure duty at the time not in the middle of speed change is found in accordance with a map, normal time line pressure control is carried out, and main processing is once finished. In this way, an effective gear ratio (ge) at a speed change commanding point A is computed from an input shaft rotation number Nt and detected car speed Nos by changing it to a mechanical gear ratio G1. A feedback control starting point is decided by a computer 14 for speed change control based on this effective gear ratio (ge) and the number of rotation of an input shaft Nt and the detected car speed Nos changing every moment. Consequently, it is possible to precisely set the feedback control starting point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for appropriately controlling a line pressure during a gear shift transition in order to reduce a shock generated during gear shifting of an automatic transmission.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission, various friction elements (clutch, brake, etc.) of a speed change gear mechanism are selectively hydraulically operated by line pressure to select a predetermined shift speed, and the friction element to be operated is changed. By doing so, gear shifting to another gear is performed.

If the line pressure is too high during this shift,
If the transient engagement capacity of the friction element becomes too large and a large shift shock occurs, and conversely if the line pressure is too low, the transitional engagement capacity of the friction element becomes too small and the slippage of the friction element increases and the automatic transmission The line pressure must be properly controlled because it will shorten the life.

Therefore, a feedback control method has been adopted in which a pressure variable mechanism such as a duty solenoid is used as the line pressure adjusting means so that a change in the rotation speed of the transmission input shaft can follow a target value. In the feedback control of the line pressure during the transition of the shift, the timing of starting the control is the time when the hydraulic chamber of the friction element that newly starts to be actuated is filled with pressure oil, that is, the engagement is started. It is desirable from the viewpoint of properly controlling the line pressure to match the time when the gear ratio of the previous gear is changed to the gear ratio of the gear after gear shift.

As a countermeasure against this, for example, a technique has been proposed in which the feedback control is started at the time when the change in the rotational speed of the prime mover at the start of the gear shift coincides with the target rotational speed change rate (see Japanese Patent Publication No. 63-54937). .

[0006]

However, the feedback control is started after switching the solenoids due to the influence of the variation of the volume of the hydraulic chamber, the solenoid characteristic, etc., or the change of the viscosity of the working oil due to the change of the oil temperature. Since the time to the point does not become a constant value, it is not easy to detect the time at which the above-described engagement is started (that is, the feedback control start point), and the above-described technique is not always sufficient.

Considering an ideal situation, using the input shaft speed Nt of the automatic transmission, the output shaft speed No, and the mechanical gear ratio G1 (= Nt / No) of the shift stage before the shift, A method of obtaining a time point that satisfies the following formula (1) can be considered. No.G1-Nt ≧ 0 (1) That is, at this time, a gear shift occurs and the gear ratio starts to change from a value before gear shift to a value after gear shift (since an upshift is considered, gears after gear shift are considered). The ratio becomes smaller), that is, the feedback control start point.

However, the actual input shaft rotation sensor and output shaft rotation sensor are not always in an ideal state because of the following problems. That is, in general, as the input shaft rotation sensor, a highly accurate one is used because it is used for various kinds of precise control, but as the output shaft rotation sensor,
Inaccurate vehicle speed sensor used for speedometer,
For example, a vehicle speed sensor that outputs only about 4 pulses per revolution is used. Therefore, especially in a region where the vehicle speed is low, there is a problem that the pulse speed output from the vehicle speed sensor is long, and thus the vehicle speed (= output shaft rotation speed) cannot be accurately detected.

Further, since the vehicle speed sensor has a low accuracy, it is not possible to obtain a pulse having a constant frequency even when the vehicle is traveling at a constant speed. Therefore, it is necessary to process a low-pass filter, and the vehicle speed sensor can detect the vehicle speed due to its influence. Since the instantaneous value is considerably lower than the true vehicle speed, the vehicle speed cannot be detected correctly from this point as well.

Therefore, if the vehicle speed cannot be detected correctly, the accurate feedback control start point cannot be detected even if the above equation (1) is used, and as a result, suitable line pressure feedback control cannot be performed. It will be. Therefore, it is conceivable to adopt a high-accuracy vehicle speed sensor instead of the low-accuracy vehicle speed sensor, but adopting a high-accuracy vehicle speed sensor only for this control leads to cost increase and is not always preferable. Absent.

The present invention has been made to solve the above-mentioned problems, and it is possible to accurately detect the line pressure feedback control start point during a gear shift transition without using an expensive vehicle speed sensor. An object of the present invention is to provide a speed change transient hydraulic pressure control device for a transmission.

[0012]

According to the invention of claim 1, the input shaft rotational speed detecting means detects the input shaft rotational speed Nt of the speed change gear mechanism, and the output shaft rotational speed detecting means detects the speed change gear mechanism. The output shaft rotation speed No. is detected, and the shift start command means instructs the shift start. And
Input shaft speed N detected by the input shaft speed detection means
From the ratio of t to the output shaft rotation speed No detected by the output shaft rotation speed detecting means, the effective gear ratio calculating means obtains the effective gear ratio ge at the time of the shift start command instructed by the shift start command means, and the effective gear ratio ge is calculated. Based on the gear ratio ge, the feedback control start point determination means determines the start point of the feedback control during the shift transition period.

That is, in the present invention, instead of the mechanically determined gear ratio, the ratio Nt / No of the input shaft rotational speed Nt and the output shaft rotational speed No at the time when the shift start command is generated.
The effective gear ratio (effective gear ratio) ge is calculated based on the calculated gear ratio, and the calculated gear ratio ge changes the gear ratio from the value before the shift to the value after the shift. Determine the point of change.

Therefore, a special high-precision sensor is not required for the sensor for detecting the number of revolutions of the output shaft of the speed change gear mechanism, and even if a low-cost sensor for detecting the speed of the conventional speedometer is shared, It is possible to accurately detect the transient state in which the stages are switched. That is, in the conventional vehicle speed sensor for speedometer, the output pulse interval of the sensor is long, and the number of revolutions of the transmission output shaft is increased because a filter with a large time constant (to compensate for variations in sensor output) is required. However, in the present invention, even in such a situation, the predetermined gear ratio Nt / No obtained by the input shaft rotation sensor and the vehicle speed sensor which is the output shaft rotation sensor is determined. It is possible to preferably detect the feedback control start point by using the change state of the timing of 1 as the execution gear ratio ge.

Therefore, even if a dedicated sensor is not set as the output shaft rotation sensor of the transmission gear mechanism, a low-cost sensor for detecting the vehicle speed of the speedometer is shared and the gear ratio changes during the period when the gear ratio changes. Feedback control,
It has a remarkable effect that it can start properly.

According to the second aspect of the present invention, as the feedback control start point determining means, a value obtained by subtracting the input shaft rotational speed Nt from the product of the output shaft rotational speed No and the effective gear ratio ge, that is, (N
It is possible to employ means for determining the feedback control start point when (o × ge−Nt) becomes equal to or greater than a predetermined value. Therefore, for example, when the predetermined value is set to the predetermined value ΔNt capable of removing the influence of noise, the influence of noise can be eliminated and the feedback control start point can be preferably detected.

According to the third aspect of the invention, the input shaft speed Nt and the output shaft speed No are used as the effective gear ratio ge,
It is possible to successively calculate the gear ratio Nt / No for a predetermined period after the shift is started by the shift start command, and to use the minimum value of the gear ratio Nt / No for that period. Therefore,
In that case, since the effective gear ratio ge can be obtained more accurately, there is an advantage that the feedback control start point can be detected more accurately.

According to the fourth aspect of the invention, the input shaft speed Nt and the output shaft speed No are used as the effective gear ratio ge,
It is possible to successively calculate the gear ratio Nt / No for a predetermined period after the shift is started by the shift start command, and to use the average value of the gear ratio Nt / No for that period. Therefore,
In that case, the variation in the effective gear ratio ge that is sequentially calculated can be smoothed, so that there is an advantage that the feedback control start point can be detected more stably.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the drawings by way of examples (embodiments). (Embodiment 1) FIG. 2 shows the overall configuration of an automatic transmission control system incorporating a control device for performing gear shift transient hydraulic pressure feedback control according to Embodiment 1.

As shown in FIG. 2, an engine 1 mounted on a vehicle and electronically controlled is connected to drive wheels 4 via an automatic transmission 2 and a differential gear 3. The engine 1 includes an engine control computer 5,
The engine control computer 5 includes an engine rotation sensor 6 for detecting an engine speed, a vehicle speed sensor 7 for detecting a vehicle speed (output shaft speed of the automatic transmission 2), and a throttle sensor for detecting a throttle opening of the engine 1. 8 and each signal of the intake air amount sensor 9 for detecting the intake air amount.

The engine control computer 5 determines the fuel injection amount based on these input information, issues a command to the engine 1, and supplies an ignition signal (not shown) to the engine 1. Then, in response to this command, a fuel supply device and an ignition device (not shown) are activated, fuel is supplied and burned in accordance with the rotation of the engine 1, and the engine 1 is driven and controlled.

The automatic transmission 2 is the torque converter 1
0 and a speed change gear mechanism 11 are provided, and the power supplied from the engine 1 is transmitted to the input shaft 12 of the speed change gear mechanism 11 via the engine output shaft 1a (see FIG. 3) and the torque converter 10. Then, the transmission input rotation to the input shaft 12 is accelerated and decelerated according to the selected speed of the speed change gear mechanism 11 to the output shaft 13 or reaches the drive wheels 4 from the output shaft 13 via the differential gear 3. You can drive a car.

Since the automatic transmission 2 is publicly known as shown in FIG. 3, its detailed description will be omitted.
The transmission gear mechanism 11 includes various clutches (R / R) that determine a power transmission path (gear stage) from the input shaft 12 to the output shaft 13.
C, H / C, LO / C, OR / C, F / C, FO / C)
It incorporates various friction elements such as brakes and brakes (B / B, LR / B).

As shown in FIG. 2, the speed change gear mechanism 11 is connected to a control valve 15 which is driven based on a command from a speed change control computer 14, and an appropriate hydraulic pressure is supplied from the control valve 15. Gear shifting is realized by operating the hydraulic pressure on various friction elements.

The control valve 15 is provided with two shift control solenoids 15 for switching the hydraulic pressure supply path for each shift stage in response to a command from the shift control computer 14.
A line pressure control solenoid 16 for controlling the magnitude of hydraulic pressure is arranged. Although the two shift control solenoids 15a and 15b are used in the present embodiment, the number of shift control solenoids may be increased depending on the number of shift stages and the internal configuration of the control valve 15. Further, a solenoid may be added to adjust the timing for the rapid filling and discharging of the hydraulic oil during the shift transition. Further, as the line pressure control solenoid 16,
In the present embodiment, the duty solenoid will be described below, but other means such as a linear solenoid may be used as long as the mechanism can change the hydraulic pressure.

Although not shown, the shift control computer 14 is composed of a microcomputer including a CPU, a ROM, a RAM, and an I / O device, and measures the rotation speed of the input shaft 12 in addition to the vehicle speed sensor 7 and the throttle sensor 8. Each signal of the input shaft rotation sensor 17 is input.

The input shaft rotation sensor 17 may be of a magnetic type, an optical type, or the like, and can generate a pulse signal proportional to the rotation of the input shaft 12. In this embodiment, the structure is shown in FIG. As shown in, a sensor using a magnetic pickup is used. Specifically, as shown in FIG. 4A, the input shaft rotation sensor 17 includes a sensor gear 17a attached to the input shaft 12, a coil 17b and a magnet 17c attached to a case 20 that houses the entire automatic transmission 2.
It consists of and.

In the input shaft rotation sensor 17, since the magnetic resistance changes depending on the presence or absence of teeth by the sensor gear 17a that rotates integrally when the input shaft 12 rotates, the magnetic flux penetrating the coil 17b changes and the coil 17
AC power is generated at both ends of b. Therefore, FIG.
As shown in FIG. 4, the resistance 17d provided in the input part of the I / O device of the shift control computer 14 causes a sinusoidal wave having a frequency proportional to the rotation speed of the input shaft 12 as shown in FIG. The voltage A is obtained. Then, if the sinusoidal voltage A is passed through an appropriate threshold element to form a pulse B and the frequency is measured, a value proportional to the rotation speed of the input shaft 12 can be obtained. In this embodiment, a signal of 32 pulses is obtained for each rotation of the input shaft 12 (16 pulses may be used for one rotation).

On the other hand, the vehicle speed sensor 7 is a sensor for detecting the rotational speed of the output shaft 13 of the speed change gear mechanism 11, and a magnetic type or optical type structure can be adopted. In this embodiment,
The most commonly used speedometer also shares the vehicle speed detection sensor. In this vehicle speed sensor 7, as shown in FIG.
As shown in, the rotation is transmitted from the output shaft 13 of the speed change gear mechanism 11 to the speedometer cable 7b through the reduction mechanism 7a. At this time, the cable 7b is 60 km for the vehicle.
It is set to rotate at a rotation speed of 637 rpm during traveling at / h.

A disc 7c is attached to the other end of the cable 7b. The disc 7c has an N pole and an S pole.
The poles are magnetized alternately. Further, a lead switch 7d is mounted near the disk 7c. Therefore, when the disk 7c (that is, the cable 7b) makes one revolution, the reed switch 7d repeats ON / OFF four times (ON / OFF), so that the vehicle speed can be detected by the ON / OFF frequency of the reed switch 7d.

Next, the shift control by the shift control computer 14 will be described with reference to the graph of FIG. The shift control computer 14 uses the signals from the vehicle speed sensor 7 and the throttle sensor 8 to change the current driving state to a shift diagram (predetermined according to the throttle opening and the vehicle speed) as shown in FIG. The gear position is determined by determining which gear region it is in. It should be noted that in the shift diagram, in order to prevent chattering when determining the shift speed, the n-th speed (n = 1,
2, 3) to n + 1-th speed shift (upshift) and m-th speed (m = 2, 3, 4) to m-1th speed shift (downshift), in the case of upshift, a solid line, In the case of downshift, different judgment lines are used as shown by the dotted lines.

Then, according to the determination result obtained based on FIG. 6, the O of the two shift control solenoids 15a and 15b is changed.
N / OFF is selected and executed as shown in Table 1 below, for example.

[0033]

[Table 1]

In this way, the shift control solenoids 15a, 15b
By controlling the ON / OFF of the control valve and driving the control valve 15, the hydraulic pressure that can be applied to various friction elements inside the speed change gear mechanism 11 changes, and the necessary clutches and brakes are activated, and The gear position is maintained or the gear shift is achieved as shown.

Further, the shift control computer 14
Also controls the line pressure control solenoid 16 as described below. In the normal case where the shift speed does not change, the hydraulic pressure (line pressure) given by the map for the throttle opening as shown in FIG. 7A is generated. Specifically, first, the required line pressure is obtained from the map of FIG. 7 (a) according to the signal from the throttle sensor 8, and then this line pressure is converted into a duty value according to the map of FIG. 7 (b). Then, the line pressure control solenoid 16 is driven at the duty value to realize the target line pressure. In this case,
It goes without saying that (a) and (b) may be integrated to directly determine the duty value from the throttle opening.

On the other hand, if there is a request to change the shift speed as a result of the shift determination performed based on FIG. 6, the shift control solenoids 15a and 15b are turned ON / OFF and the shift shock is softened. In order to control the line pressure. The method will be described by taking an upshift as an example. Starting from a predetermined initial hydraulic pressure, the output shaft 13 starts with a predetermined initial hydraulic pressure depending on the shift speed, the throttle opening, the torque generated by the engine 1 and the torque generated by the input shaft 12. The line pressure is feedback-controlled so that a change in the rotational speed of the input shaft 12 that is set so that the torque change has a predetermined shape can be obtained. As an example of the setting of the initial hydraulic pressure, the setting based on the throttle opening is shown in FIG.

In this way, the line pressure feedback control is performed at the time of transition of the speed change. At the start of the line control, the hydraulic chamber of the friction element that newly starts operation is filled with the pressure oil,
It is desirable to set the time to start the engagement, that is, the point at which the change starts from the gear ratio of the shift stage before the shift to the gear ratio of the shift stage after the shift.

However, the shift control solenoid 15 is switched due to the influence of variations in the volume of the hydraulic chamber, the solenoid characteristic shown in FIG. 7B, or the like, or changes in the viscosity of the hydraulic oil due to changes in the oil temperature. The time from to the point at which the feedback control is started does not have a constant value. Therefore, an operation of detecting this time is required.

Considering an ideal situation, using the rotation speed Nt of the input shaft 12, the rotation speed No of the output shaft 13, and the mechanical gear ratio G1 (= Nt / No) of the shift stage before the shift, (N
It suffices to find the time when the value of (o · G1-Nt) becomes a positive value apart from zero. That is, this point is the point at which the gear ratio starts to change from the value before the gear shift to the value after the gear shift (since the upshift is considered, the gear ratio after the gear shift becomes smaller). However, as shown in FIGS. 4 and 5, a problem arises when the vehicle speed sensor 7, which is the actual rotation sensor of the input shaft rotation sensor 17 and the output shaft 13, is used.

That is, in a region where the vehicle speed is low, the interval between the pulses output by the vehicle speed sensor 7 is long, so that the vehicle speed (= the rotation speed of the output shaft 13) No can not be detected accurately. Further, since the accuracy of the vehicle speed sensor 7 is low, pulses of a constant frequency cannot be obtained even when the vehicle travels at a constant speed. Therefore, it is necessary to process the low-pass filter, and from this influence, the detected vehicle speed obtained by the measurement can be obtained. Nos is shown in FIG.
As shown in, the instantaneous value is considerably lower than the true vehicle speed No.

Therefore, the detected vehicle speed Nos is used to calculate the feedback control start point similar to the ideal state (No.
sG1-Nt), the value of NosG1 becomes a value considerably smaller than the input shaft rotational speed Nt as shown by the broken line in FIG. 8, so the same determination as in the ideal state is performed. I can't.

Therefore, in this embodiment, the gear ratio Nt / Nos (= effective gear ratio; g) between the input shaft rotational speed Nt and the detected vehicle speed Nos at the point where the shift command is generated (point A in FIG. 8).
e) is calculated. Then, when the effective gear ratio ge is calculated moment by moment, the value gradually approaches the true gear ratio G1, but after the gear shift command is issued (point A in FIG. 8), the feedback control start point (in FIG. 8). 100 up to point B)
Since it is as short as about msec or less, the effective gear ratio ge during that period is
The error does not occur even if it is regarded as small and constant.

Therefore, the value of (Nos.ge-Nt) is calculated using the effective gear ratio ge at the time when the shift command is generated, and the point at which this value changes from zero to a positive value is the feedback start point. (Corresponding to point B'in FIG. 8). However,
Actually, considering the influence of noise and the like, the point that satisfies the following expression (2) is set to the feedback control start point (B ″ in FIG. 8).
Points).

Nos · ge−Nt ≧ ΔNt (2) If the value of ΔNt is too small, it is greatly affected by noise, and if it is too large, the feedback control start point is delayed. A value of about 50 to 150 rpm is selected in consideration of the response speed of the system.

Next, in order to execute the above control, the control executed by the shift control computer 14 is
This will be described based on the flowchart of FIG. First, in step 210, the throttle opening, the detected vehicle speed Nos, and the input shaft speed Nt of the speed change gear mechanism 11 required for the speed change determination are read.

In the following step 220, it is determined whether or not there is a shift according to the shift diagram shown in the map of FIG. That is, it is determined that there is a shift when the line connecting the relational position of the vehicle speed-slottle opening in the previous calculation and the relational position in this calculation crosses the solid line or the broken line.

If it is determined in step 220 that there is a gear shift, the routine proceeds to step 230, where gear shift start control is executed. In order to generate ON / OFF of the shift control solenoid 15 based on Table 1 and the line pressure shown by the broken line in FIG. 7A, the line pressure control solenoid 16 is operated according to FIG. 7B. It is driven by duty.

In the following step 240, the input shaft speed N
The effective gear ratio ge at the gear shift command point A is calculated from t and the detected vehicle speed Nos based on the following equation (3). ge = Nt / Nos (3) In the following step 250, F, which is a parameter indicating the feedback control start point, is calculated from the input shaft speed Nt, the detected vehicle speed Nos, and the effective gear ratio ge based on the following formula (4). To calculate.

F = Nos.ge-Nt (4) At the next step 260, the start point parameter F and the set value .DELTA.Nt for eliminating the influence of noise are compared. If it is determined that F <ΔNt in this comparison, it is determined that the filling period of the friction element chamber has not ended yet, and the process proceeds to step 270, and the duty of the solenoid drive state set in step 230 is held. By doing so, the initial hydraulic pressure for shifting is maintained.

After that, the routine proceeds to step 271, where the input shaft speed Nt and the detected vehicle speed Nos are read again, and the routine returns to step 250. On the other hand, in the determination of step 260, F ≧ ΔN
If it is determined to be t, the routine proceeds to step 280, where feedback control is performed so that the rotation speed Nt of the input shaft 12 changes in a predetermined manner.

The control in step 280 is repeatedly executed until it is determined in the shift end determination in the following step 290 that the shift is completed. When it is determined that the shift is completed, this process is once terminated. In the case of the upshift just described, in the determination of the end of step 290, the direction of the change of the input shaft rotation speed Nt is opposite, that is, the rotation speed Nt that has decreased due to the progress of the shift increases again. It suffices to detect the turning point. Alternatively, the difference between the input shaft rotational speed Nt and the value obtained by multiplying the detected vehicle speed Nos by the gear ratio g2 of the stage in which the speed change of the speed change gear mechanism 11 is in progress (Nt-Nos.g2).
However, the determination may be made by detecting when the value becomes a predetermined value (for example, 50 rpm) or less.

If it is determined in step 220 that the gear change is not in progress, the process proceeds to step 300, in which the line pressure duty when not in the gear change is obtained according to the map of FIG. Pressure control,
This process ends once. As described above, in this embodiment, instead of the mechanical gear ratio G1, the effective gear ratio ge at the gear shift command point A is calculated from the input shaft rotation speed Nt and the detected vehicle speed Nos, and this effective gear ratio ge is added every second. Since the feedback control start point is determined on the basis of the input shaft rotation speed Nt and the detected vehicle speed Nos that change with, the remarkable effect that the feedback control start point can be set accurately can be obtained.

Further, since the actual start of feedback control is set at the time when the starting point parameter F becomes ΔNt or more, the effect of noise or the like can be eliminated. Also, by devising signal processing,
There is an advantage that the line pressure can be controlled more precisely and there is no need to change the configuration of the conventional sensor.

In other words, according to the present embodiment, it is possible to execute appropriate hydraulic pressure control at the start of gear shifting without changing the hardware configuration, and also to start feedback control at an optimum time point. (Second Embodiment) Next, a second embodiment will be described. Since the hardware configuration and the like are the same as those of the first embodiment, only different points will be described in detail.

In this embodiment, the starting point of the feedback control is determined by the process using the effective gear ratio ge as in the first embodiment, but the determination method is slightly different. In other words, in the first embodiment, since the period from the shift command (point A in FIG. 8) to the feedback control start point (point B in FIG. 8) is short, the change in the effective gear ratio ge during that period is small and should be ignored. However, here, the performance of the vehicle speed sensor 7 is maximized so as to more accurately capture the change in the gear ratio.

Specifically, by calculating the effective gear ratio ge (= Nt / Nos) successively for a predetermined period after the gear shift command, the minimum value thereof is calculated to obtain a more accurate effective gear ratio ge.
And the same processing as in the first embodiment is performed using this effective gear ratio ge.

This concept is shown in FIG. 10 (a). In this figure, the output of the input shaft rotation sensor 17 (input shaft rotation speed N
t) is shown as an analog value which approximates to an ideal one. On the other hand, the output of the vehicle speed sensor 7 (detected vehicle speed Nos)
Shows a staircase (sawtooth wave), which is
This is because the pulse interval from the vehicle speed sensor 7 is long and the vehicle speed value is not updated during the pulse interval.

Therefore, after the gear shift command, the vehicle speed pulse interval becomes shorter as the vehicle speed increases, and the detection accuracy of the vehicle speed sensor 7 is effectively improved. Therefore, the effective gear ratio ge is a mechanical gear ratio. Approaching G1. Further, since the detected vehicle speed Nos is stepwise, the effective gear ratio ge also changes stepwise. In the first embodiment, the envelope of the effective gear ratio ge is approximated to be constant because it does not change because it is in a short time.

Therefore, in the period T1 from the shift command point A to the feedback control start point B, the effective gear ge (= Nt / N
If the minimum value of (os) is calculated, the most correct value as the effective gear ratio ge will be obtained. Therefore, actually, the effective gear ratio ge is calculated by the following method.

In the hydraulic system used in this embodiment, T1
It is known from the preliminary experimental result that the value of is within the range of 130 to 150 msec. Therefore, as shown in FIG. 10 (b), Ts (80 to 128 msec, for example, 96 msec) shorter than that is effective for a period of time. The gear ratio ge is repeatedly calculated (for example, every 16 msec calculation cycle), and the minimum value thereof is set as the effective gear ratio ge.

Next, the above procedure will be described with reference to the flowchart of FIG. In step 310 of FIG. 11, the throttle opening and the detected vehicle speed No. necessary for the shift determination are set.
s, the input shaft speed Nt of the speed change gear mechanism 11 is read.
In the following step 320, the presence or absence of a shift is determined according to the shift diagram shown in the map of FIG. 6, and if it is determined that there is a shift, the process proceeds to step 330,
Clear the counter T.

In the following step 340, the shift start control is executed in the same manner as in step 230 of the first embodiment.
In the following step 350, the counter T is incremented. In the following step 360, it is determined whether or not the counter T exceeds 6. That is, assuming that the calculation of the effective gear ratio ge is performed every 16 msec, the period Ts is 96 msec in 16 × 6. Therefore, the counter T determines whether or not the period Ts has elapsed from the shift command point A. To do.

If it is determined that the period Ts has not elapsed (that is, T ≦ 6), then in step 370, the current effective gear ratio geo is calculated from the input shaft speed Nt and the detected vehicle speed Nos. (= Nt / Nos) is calculated. In the following step 371, it is determined whether or not the counter T is 1, that is, whether or not it is the first loop operation. YE in this judgment
If it is determined that S is the first loop calculation, the process proceeds to step 373, and the current value of the effective gear ratio geo is substituted for the effective gear ratio ge. After that, the process proceeds to step 380. If the determination in step 371 is NO, that is, the second or later determination, the process proceeds to step 372.

In step 372, the effective gear ratio ge obtained by the previous loop calculation and the current effective gear ratio g
When eo is compared and it is determined that the current effective gear ratio geo is smaller, the routine proceeds to step 373, where the current effective gear ratio geo is substituted for the effective gear ratio ge.
By repeating this processing for the number of loops (6 times), the minimum value of the effective gear ratio ge during the predetermined period is obtained. Then, it progresses to step 380.

If it is determined in step 372 that the current effective gear ratio geo is larger than the effective gear ratio ge, no operation is performed and immediately step 380 is performed.
Proceed to. In step 380, the initial hydraulic pressure is maintained, and in subsequent step 381, the input shaft speed Nt and the detected vehicle speed N are again set.
Read os.

Then, the process returns to step 350 and the counter is incremented. On the other hand, the step 360
If it is determined that the period Ts has elapsed, the step 3
At 90, F (= Nos · ge−Nt), which is a parameter indicating the feedback control start point, is calculated from the input shaft rotation speed Nt, the detected vehicle speed Nos, and the effective gear ratio ge.

In the following step 400, the starting point parameter F is compared with the set value ΔNt for eliminating the influence of noise. If it is determined that F <ΔNt in this comparison, it is determined that the filling period of the friction element chamber has not ended yet, and the routine proceeds to step 410, where the duty of the solenoid drive state set at step 340 is held. By doing so, the initial hydraulic pressure for shifting is maintained.

After that, the routine proceeds to step 411, where the input shaft speed Nt and the detected vehicle speed Nos are read again, and step 3
Return to 90. On the other hand, in the determination of step 400, F ≧ ΔNt
If it is determined that the input shaft rotation speed Nt is in the predetermined range, feedback control is performed so that the input shaft rotation speed Nt changes in a predetermined manner.

The control of step 420 is repeatedly executed until it is determined in the shift end determination of the following step 430 that the shift is completed. When it is determined that the shift is completed, this process is once terminated. If it is determined in step 320 that gear shifting is not in progress, step 440
7, the line pressure duty at the time of non-shift is obtained according to the map of FIG. 7, the normal line pressure control is executed, and this processing is once ended.

Thus, in this embodiment, the effective gear ratio ge is calculated every 16 ms until the period Ts elapses,
Since the feedback control start point is determined by using this effective gear ratio ge, there is a remarkable effect that the feedback control start point can be set more accurately than in the first embodiment.

Further, according to this method, as shown in FIG. 10B, the point C near the apex of the sawtooth wave and the shift command point A
Even when the timings of and overlap, like Example 1,
There is an advantage that it is possible to prevent the effective gear ratio ge from being calculated as a large value. (Third Embodiment) Next, a third embodiment will be described. Since the hardware configuration and the like are the same as those of the first embodiment, only different points will be described in detail.

In this embodiment, the average value of the gear ratios calculated during the period Ts is the effective gear ratio ge. This is because the vehicle speed changes stepwise even in the vicinity of the feedback control start point, and even when the determination is made by the following equation (5), the detected vehicle speed Nos may be too small depending on the timing of calculation, and the determination may be erroneous. Because there is.

Nos · ge−Nt ≧ ΔNt (5) In other words, if the effective gear ratio ge is set to an average value, the influence of calculation error on the stepwise change of the detected vehicle speed Nos can be reduced, so that the correct timing can be obtained. Thus, there is an effect that the time when the feedback control should be started can be detected.

Next, the above procedure will be described with reference to the flowchart of FIG. In step 510 of FIG. 12, the throttle opening, the vehicle speed Nos, and the input shaft speed Nt of the speed change gear mechanism 11 required for the speed change determination are read. In the following step 520, it is determined whether or not there is a shift according to the shift diagram shown in the map of FIG. 6, and if it is determined that there is a shift, the process proceeds to step 530 to clear the counter T.

In the following step 540, the shift start control is executed in the same manner as in step 230 of the first embodiment,
In the following step 550, the counter T is incremented. In the following step 560, it is determined whether the counter T exceeds 6. That is, assuming that the calculation of the effective gear ratio ge is performed every 16 msec, the period Ts is 96 msec in 16 × 6. Therefore, the counter T determines whether or not the period Ts has elapsed from the shift command point A. To do.

If it is determined that the period Ts has not elapsed, then in step 570, the current effective gear ratio ge (T) (=) is calculated from the input shaft speed Nt and the detected vehicle speed Nos.
Nt / Nos, T = 1-6) is calculated. In the following step 580, the initial hydraulic pressure is held, and in the following step 581, the input shaft rotation speed Nt and the detected vehicle speed Nos are read again.

Thereafter, the process returns to step 550, and the counter T is incremented. On the other hand, the step 56
When it is determined that the period Ts has elapsed at 0, the process proceeds to step 561. In step 561, the effective gear ratio ge is calculated as the average value of the effective gear ratios ge (T) during the period Ts by the following equation (6).

Ge = {ge (1) + ge (2) + ge (3) + ge (4) + ge (5) + ge (6)} / 6 (6) At the subsequent step 590, the input shaft rotational speed Nt is detected. From the vehicle speed Nos and the effective gear ratio ge, F (= Nos · ge−N) which is a parameter indicating the feedback control start point
Calculate t).

In the following step 600, the starting point parameter F is compared with the set value ΔNt for eliminating the influence of noise. If it is determined that F <ΔNt in this comparison, it is determined that the filling period of the friction element chamber has not ended yet, and the process proceeds to step 610, and the duty of the solenoid drive state set in step 540 is held. By doing so, the initial hydraulic pressure for shifting is maintained.

After that, the routine proceeds to step 611, where the input shaft speed Nt and the detected vehicle speed Nos are read again, and step 5
Return to 90. On the other hand, when F ≧ Nt is determined in the comparison in step 600, the process proceeds to step 620, and feedback control is performed so that the input shaft rotation speed Nt changes in a predetermined manner.

The control of step 620 is repeatedly executed until it is determined in the shift end determination of the following step 630 that the shift is completed. When it is determined that the shift is completed, this process is once terminated. If it is determined in step 520 that gear shifting is not in progress, step 64
In step 0, the line pressure duty at the time of non-shift is calculated according to the map of FIG. 7, the normal line pressure control is executed, and this control is once terminated.

As described above, in this embodiment, the current effective gear ratio ge is sequentially obtained every 16 ms until the period Ts elapses.
(T) is calculated, and then the arithmetic mean value thereof is calculated as the effective gear ratio ge. And this effective gear ratio ge
Since the feedback control start point is determined by using, there is a remarkable effect that the feedback control start point can be set more accurately than in the first embodiment.

It is needless to say that the present invention is not limited to the above-mentioned embodiments and can be carried out in various modes without departing from the scope of the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the configuration of the invention of claim 1.

FIG. 2 is a schematic configuration diagram showing an overall configuration of an automatic transmission control system incorporating the control device of the first embodiment.

FIG. 3 is a schematic configuration diagram showing a configuration of an automatic transmission.

FIG. 4 is an explanatory diagram showing a configuration of an input shaft rotation sensor.

FIG. 5 is an explanatory diagram showing a configuration of a vehicle speed sensor.

FIG. 6 is a graph showing shift lines for upshift and downshift.

FIG. 7 shows various maps, (a) is a map for obtaining the line pressure from the throttle opening, and (b) is a map for obtaining the duty value from the line pressure.

FIG. 8 is a timing chart showing a gear shift state according to the first embodiment.

FIG. 9 is a flowchart showing a control process of the shift control computer according to the first embodiment.

FIG. 10 is a timing chart showing a gear shift state according to the second embodiment.

FIG. 11 is a flowchart showing a control process of a shift control computer according to the second embodiment.

FIG. 12 is a flowchart showing a control process of a shift control computer according to a third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Automatic transmission 5 ... Engine control computer 6 ... Engine rotation sensor 7 ... Vehicle speed sensor 8 ... Throttle sensor 10 ... Torque converter 11 ... Shift gear mechanism 12 ... Input shaft 13 ... Output shaft 14 ... Shift control computer 15 ... Control valve 15a, 15b ... Shift control solenoid 16 ... Line pressure control solenoid 17 ... Input shaft rotation sensor

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Claims (4)

[Claims] 1. An automatic transmission in which each friction element of a speed change gear mechanism is selectively hydraulically actuated by line pressure to select a predetermined shift speed, and a friction element to be operated is changed to shift to another shift speed. A shift transient hydraulic control device for an automatic transmission, which is used to reduce feedback shock to a line pressure during a shift transient period during which a shift is actually performed, detects a rotation speed of an input shaft of the shift gear mechanism. Input shaft rotation speed detection means, output shaft rotation speed detection means for detecting the output shaft rotation speed of the speed change gear mechanism, and shift start command means for instructing the start of the speed change. Shift start command issued by the shift start command means from the ratio of the input shaft rotation speed detected by the means and the output shaft rotation speed detected by the output shaft rotation speed detection means. Effective gear ratio calculating means for obtaining an effective gear ratio at a time point, and feedback control start point judging means for judging a starting point of feedback control in the shift transition period based on the effective gear ratio calculated by the effective gear ratio calculating means. And a shift transient hydraulic pressure control device for an automatic transmission, comprising: 2. The feedback control start point determination means is configured to provide the feedback control when the value obtained by subtracting the input shaft rotation speed from the product of the output shaft rotation speed and the effective gear ratio becomes a predetermined value or more. 2. The shift transient hydraulic pressure control device for an automatic transmission according to claim 1, wherein the control start point is determined. 3. A gear ratio, which is a ratio of the input shaft rotation speed and the output shaft rotation speed, is sequentially calculated for a predetermined period after the shift is started by the shift start command, and the minimum gear ratio in the period is calculated. 3. The shift transient hydraulic pressure control device for an automatic transmission according to claim 1, wherein the value is the effective gear ratio. 4. A gear ratio, which is a ratio between the input shaft rotation speed and the output shaft rotation speed, is sequentially calculated for a predetermined period after the shift is started by the shift start command, and an average of the gear ratios during the period is calculated. 3. The shift transient hydraulic pressure control device for an automatic transmission according to claim 1, wherein the value is the effective gear ratio.