JPS6367450A - Control method of automatic transmission - Google Patents

Abstract

PURPOSE:To protect an engine from overrun by automatically controlling the up-shift pattern so that it is changed into the low-speed side when the viscosity of transmission gear oil is not less than a prescribed value and the total number of speed changes of the same type after the engine is started is not more than a prescribed value. CONSTITUTION:When the oil temperature of transmission gear oil in an automatic transmission is low and the number of times of the same type of up-shift is not more than a prescribed number of times, the points of speed change A12, A23, A34, that are in the lower-speed side respectively than the points of speed change B12, B23, B34 that are used ordinarily, are set as an up-shit pattern for the speed change control routine. Hereupon, when the oil temperature is low and the number of speed changes is small, that is, when the time required from a speed-change command to a speed-change start becomes longer, the speed-change command is carried out according to a gear-shift pattern that is set at a lower-speed side than that for ordinary use. Consequently, in a state where the viscosity of transmission gear oil is high and the supply of transmission gear oil to a friction engaging device delays so that the start of sped change can delay, the speed-change command is carried out an a lower-speed side than that for ordinary use, and the speed-change start is carried out at an engine speed that is equal to or lower than the ordinary one, and therefore, an engine can be protected from overrun.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling an automatic transmission when the transmission oil of the automatic transmission has high viscosity.

[Prior Art] The shift point of an automatic transmission ('A/T) is determined according to a predetermined shift pattern based on the engine load, such as the throttle opening, and the vehicle speed, such as the output shaft rotation speed of the automatic transmission. ing.

Conventionally, as a shift control method for an automatic transmission using such shift patterns, methods have been proposed in which an optimal shift pattern is selected using various wheels 1.

For example, the technology disclosed in Japanese Patent Publication No. 48-217 changes the floor pattern to the high speed side when the temperature of the transmission oil of the torque converter rises due to mountainous driving etc. [This aims to improve the performance and prevent overheating of the torque converter.

[Problems to be Solved by the Invention] These conventional techniques are excellent in preventing overheating of the torque converter, but when the temperature of the transmission part of the automatic transmission is low and the viscosity of the transmission part is high. No special consideration was given to the behavior of such automatic transmissions, and the following problems were considered.

At low temperatures (for example, below 0° C.), the viscosity of the transmission section increases, and the resistance to oil passage through the transmission section through the supply oil path to the frictional engagement device for shifting increases. For this reason,
When the vehicle is in motion, where the transmission section is not filled in the supply oil path to the frictional engagement device, the transmission section is actually supplied to the frictional engagement device from the time when the supply of oil from the transmission section to the frictional engagement device is started. The time until oil is supplied is at normal oil temperature (e.g. 0°C)
(above) may be longer. As a result, there is a problem in that the engine may overrun.

The mechanism of occurrence of this overrun will be explained based on FIG. 7. FIG. 7 is a graph showing changes in engine speed, A/H output shaft torque, and oil pressure of the transmission section during gear shifting, where the solid line indicates the characteristics at normal oil temperature, and the dotted line indicates the characteristics at normal oil temperature. This shows the characteristics at low oil temperature (-20°C). In FIG. 7, a time point "la" indicates the time point at which an upshift is commanded, a time point Tb indicates a time point at which a shift is started at normal oil temperature, and a time point Tc indicates a time point at which a shift starts at a low oil temperature. As shown in the figure, at normal oil temperature, the oil pressure reaches the engagement start oil pressure PC of the frictional engagement device at time Tb, and the gear shift starts at the engine rotation speed Nb.On the other hand, at low oil temperature, As shown by the dotted line, it takes time until time TC to reach the engagement start oil pressure pc, and during this time the engine speed continues to rise, and at time TC when the shift starts, the above-mentioned rotation speed Nb is reached. This results in a higher engine speed NC.Therefore, when the oil temperature is low, the engine speed at the start of an upshift increases, so there is a problem that there is a possibility that the engine will overrun when upshifting at full throttle. there were.

To explain this in accordance with the upshift pattern shown in Fig. 8, when shifting in the full throttle region (throttle opening 85 to 100%) of the upshift pattern, for example, the allowable vehicle speed of 3rd gear is a shift of ■7. If an upshift is performed on the line, if the supply to the transmission section is delayed, the vehicle speed at the start of the shift will be considerably higher than the V7, and if it remains in 3rd gear, the vehicle speed will rise to the point where engine overrun will occur. This is a phenomenon.

An object of the present invention is to solve the above-mentioned problem and prevent an overrun during an upshift immediately after fetal movement when a vehicle is started with a high viscosity in the transmission section of an automatic transmission. shall be.

[Means for Solving the Problems] As a means for achieving the above object, the present invention, as illustrated in FIG.
In an automatic transmission control method in which the automatic transmission is controlled by a transmission section based on the running condition of the vehicle, the viscosity of the transmission section of the automatic transmission is equal to or higher than a predetermined value (step A), and after the engine is started. The automatic transmission control method is characterized in that when the number of the same type of gear shifting is less than a predetermined number (step B), the upshift pattern is changed to a lower speed side (step C). .

The judgment that the viscosity of the transmission section is above a predetermined value may be made by directly detecting the viscosity with a rotational viscometer, or by measuring the temperature of the transmission section, the engine water temperature, or the air temperature.
etc. is below O'C, or when the engine rotational speed after engine startup or the cumulative rotational speed of the output shaft rotational speed of the automatic transmission is below a predetermined rotational speed.

The above-mentioned same type of shifting means, for example, 1st gear → 2nd gear, 2nd gear → 3rd gear.
speed, or the type of individual speed change such as from 3rd speed to 4th speed.

Changing the upshift pattern to a lower speed side when the viscosity of the transmission section of the automatic transmission is above a predetermined value and the number of shifts of the same type after starting the engine is less than or equal to the predetermined number means, for example, the transmission section, Or, if the engine water temperature is below O'C and the upshift from 1st to 2nd gear is less than 5 times, the shift from 1st to 2nd gear shown by the solid line in the upshift pattern in Figure 2. This is to change the upshift line US12 to an upshift line UT12 shown by a dotted line. The second
The upshift pattern in the figure shows the vehicle speed on the horizontal axis and the engine load on the vertical axis, and the solid line is the upshift line at normal shift oil temperature US12 (1st gear → 2nd gear), US23 (2nd gear → 3rd gear)
, and tJs34 (3rd gear → 4th gear), and the dotted lines indicate upshift lines UT12 (1st gear → 2nd gear) and UT23 (2nd gear → 3rd gear) when the gear shift oil temperature is low and the number of gear shifts is below the predetermined number.
speed), and UT34 (3rd speed → 4th speed).

[Function] According to the automatic transmission control method of the present invention, when the viscosity of the transmission oil is higher than a predetermined value and the number of times of the same type of gear change after starting the engine is less than or equal to the predetermined number, r!
! The upshift pattern of the automatic transmission is changed to a lower speed side since the start of the actual shift in the ti engagement device is delayed. Therefore, an upshift command to the automatic transmission is issued at a low vehicle speed, that is, at a lower engine speed than normal.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 3 to 6.

In FIG. 3, 10 is an engine and 20 is an automatic transmission. The automatic transmission 20 has a structure shown in FIG. 4, which will be described later, in which oil pressure is controlled by energizing and de-energizing electromagnetic valves 21a, 21b, and 21c, thereby enabling four-speed shifting and operation of a direct coupling clutch.

The electromagnetic valves 21a, 21b, and 21c are driven by signals from a control circuit 30, which is connected to the engine 10. Signals from sensors placed in various parts of the vehicle, including the automatic transmission 20, are input.

These sensors include a throttle opening sensor 14 . Engine rotation speed sensor 16° that detects the rotation speed of the engine 10 Automatic gear shift 1 proportional to vehicle speed
Vehicle speed sensor that detects the rotation speed of output shaft 20C of m20 + J22° automatic transmission UN 20 oil'fAk
It is composed of an oil temperature sensor 23 and the like that detects the oil temperature.

The control circuit 30 is constituted by a well-known microcomputer, that is, a CPU 31. RAM32, ROM3
3. Input port 34. It is composed of an output port 35, a common bus 36, and the like. The input port 34 receives signals from the above-mentioned sensors through a pulse input section 37a,
37b or A/D converter 37G, or directly. The output port 35 is connected to electromagnetic valve drive units 38a, 38b, and 38c. The ROM 33 stores control programs, data, etc. corresponding to the control flowchart of this embodiment.
The control circuit 30 executes the control of this embodiment, the speed change control, etc. in accordance with this.

Next, the configuration of the automatic transmission 20 will be explained with reference to the skeleton diagram of FIG. 4. Automatic shift ff! 20, which is known per se, is an input shaft 102.20 connected to the output shaft of the engine 10. Hydraulic torque converter 103.
A direct coupling clutch 104° bypasses the torque converter 103 and directly connects the input shaft 102 to the output shaft 103a of the torque converter.A shaft 105 connected to the output shaft 103a of the torque converter is used as an input shaft, and several gear stages are provided to this. The gear shift mechanism 107 outputs a drive signal j for driving the drive wheels of the vehicle to the output shaft 106 .

The gear transmission mechanism 107 includes a carrier 108 . connected to the input shaft 105 . A planetary pinion 109 carried by the carrier 108. A sun gear 110 and a ring gear 111 engaged with the planetary pinion 109, a one-way clutch FO provided between the carrier 108 and the sun gear 110, a clutch CO that selectively couples the carrier 108 and the sun gear 110, and a sun gear 110 selected for the housing. It has an overdrive mechanism including a brake BO that fixes the brake.

Gear transmission 194107 further includes clutch C1 and clutch C2 that selectively connect intermediate N115 or sun gear shaft 116 to ring gear 111.

Ring gear 119 connected to intermediate N115. Sun gear 120 connected to sun gear shaft 116. Ring gear 11
9 and V gear 120 and carried by a carrier 121 connected to the output shaft 106. Sun gear 123 connected to sun gear shaft 116, ring gear 12 connected to output shaft 106
4. Planetary pinion 125 meshed between sun gear 123 and ring gear 124. A carrier 126 carrying the planetary pinion. A brake B1 selectively fixes the sun gear shaft 116 to the housing; a brake B2 selectively fixes the sun gear shaft to the housing via a one-way clutch F1; A transmission device that achieves three forward gears and one reverse gear, including a one-way clutch F2 that fixes the carrier 126 against rotation in one direction with respect to the housing, and a brake B3 that selectively fixes the carrier 126 with respect to the housing. Contains.

The direct coupling clutch 104 in the automatic transmission 20 and the clutches Co and CI in the gear transmission mechanism '107.

C2, and brake 80. Bl, B2, 83 are selectively supplied with hydraulic pressure by the solenoid valves 21a to 21c, or the supplied hydraulic pressure is discharged.
As a result, the direct coupling clutch is selectively engaged or disengaged, and four forward speeds and one reverse speed, including A-patrive, are achieved.

Table 1 shows the solenoid NO, 1 of the solenoid valves 21a to 21G in each of the gears achieved under various shift ranges for the automatic transmission 20 based on FIGS. 3 and 4.
This is a list showing the energization and de-energization of ~No. 3 and the engagement states of friction engagement mechanisms such as clutches C0-02 and brakes Bo-B3 and one-way clutches FO-F2. In this list, the shift range D, 2. L, R, P,
N indicates D range, 2 range, L range, reverse range, parking, neutral, and gear '+st'
, 2nd, 3rd, 4th, R are 1st gear and 2nd gear, respectively.
3rd speed, 4th speed, and reverse gear. Furthermore, in this list, for solenoids No. 1 to No. 023, the ○ mark indicates that they are energized (ON), the X mark indicates that they are in the de-energized state (OFF>, and ◎ The mark indicates that the direct coupling clutch 4 is energized when it should be engaged (L/CON>. Also, in the same table, regarding the friction engagement mechanism (clutch GO-C2, brake BO-83), these are It is engaged only when the O mark is marked, and is disengaged when the other X marks are attached.Similarly, for one-way clutches FO to F2, ■ is used in conjunction with a friction engagement element for engine braking. This shows that it does not actually function as a one-way clutch.○
locks and transmits power when the engine is powered on,
Indicates that it is free during j-strike. An X indicates that it is released.

Table 1 Figure 5 shows the fruit and gland 312.823. B34 and dashed line A
12°A23. As shown by A34, in this example,
Two systems of upshift lines are used for shifting, particularly upshifting, of the automatic transmission 20 under the control of the control circuit 30. That is, the upshift line (broken line) showing the shift point A12 from 1st gear to 2nd gear, the shift point A23 from 2nd gear to 3rd gear, the shift point A34 from 3rd gear to 4th gear, and the shift point 812 from 1st gear to 2nd gear. .2
This is an upshift line (solid line) showing a shift point 823 from speed to third speed and a shift point 334 from third speed to fourth speed. In this example, the above-mentioned shift point A (A12, A23°A34) is set to
When the temperature is 0° C. or lower and the number of times of the same type of shift is less than a predetermined number, the upshift shift point of the same type is set. For example, if the oil temperature is below 110℃ and the number of upshifts from 1st gear to 2nd gear is 5 times or less, 13a→
A shift point A12 for shifting to second gear is set. On the other hand, the shift point B (812, 823, 834>) means that the shift point A is 8.
2. This is set in cases other than those specified.

Next, the control method of this embodiment will be explained based on the flowchart shown in FIG. The control circuit 30 repeatedly executes a shift point changing routine shown in FIG. 6 when the vehicle starts running. First, the oil temperature of the transmission oil of the automatic transmission 20 is read in °C (oil temperature monitor) (step 41
0>, the oil temperature k is a preset predetermined temperature t'c(-1
0℃) (step 420)
.

If the oil temperature k is lower than the predetermined temperature t, then the number n12 of upshifts from 1st gear to 2nd gear becomes the predetermined number nA.
(in this case, 5 times). If n12<nA, the shift point A12 is set at the shift point from 1st gear to 2nd gear (step 440). ). Next, it is determined whether the number of upshifts from second gear to third gear n23 is smaller than a predetermined number nB (here, 6 times) (step 450), and n2
If 3<nB, shift point △2 at the shift point from 2nd gear to 3rd gear
3 is zeroed (step 460). Next, 3rd gear → 4th gear
It is determined whether the number of upshifts n34 is smaller than a predetermined number nC (7 times in this case) (step 470), and if n34<nc, the shift point from 3rd gear to 4th gear is reached. A shift point A34 is set (step 480).

Note that the predetermined times nA, n8. and.

nc is predetermined in consideration of the supply oil path length in the automatic transmission vi 20, etc.

After the shift point is set, it is determined in a shift control routine (not shown) whether a shift command has been issued based on the vehicle speed and throttle opening t according to the shift pattern (step 490). Then, the gear change command is sent to automatic transmission 2.
0, the type of the shift command is determined and the corresponding number of upshifts n12. n
23. Alternatively, n34 is incremented (steps 500 to 550). In other words, if the above shift command is 1st gear →
In the case of an upshift to second gear (step 500),
Increment the number of upshifts n12 in step 510>, and in the case of an upshift from 2nd gear to 3rd gear (
In step 520), the number of times n23 is incremented. In the case of upshifting from third speed to fourth speed (step 540), the number of times n34 is incremented (step 550).

Thus, each time an upshift is made, the number of upshifts of the corresponding type n12. n23. Since n34 is incremented, step 430 described above
, 450.470, each upshift after starting the engine 10 n12, n23. n3
4, each predetermined number of times nA, nB.

The state exceeds nc. In such a case, if it is determined in step 470 that the number of upshifts from 3rd gear to 4th gear is greater than or equal to the predetermined number of upshifts nC, the shift will be performed from 3rd gear to 4th gear. Point 334 is set (step 560). On the other hand, step 450
If it is determined that the number of upshifts from 2nd speed to 3rd speed n23 is equal to or greater than the predetermined number i1 n 8, a shift point 823 and a shift point B34 are set (step 5).
70). At step 430 or step 420,
The number of upshifts from 1st gear to 2nd gear "]12 is the predetermined number i
If it is determined that the oil temperature is equal to or higher than nA, or if it is determined that the oil temperature k is equal to or higher than the predetermined temperature, the shift points 812, 323 and 334 are let. In this way, when the number of upshifts exceeds a predetermined number, the shift point on the upper gear side from that shift point is simultaneously changed to shift point B, thereby preventing the intersection of shift point A and shift point B. Ru.

As explained above, according to this embodiment, when the oil temperature is low and the number of upshifts of the same type is less than a predetermined number, the shift point A is lower than the normally used shift point B.
is set as an upshift pattern in a shift control routine (not shown).

Therefore, when the oil temperature is low and the number of gear shifts is small,
In other words, if the time from when the shift command is actually started is long, the shift command is performed according to a shift pattern set to a lower speed than usual. As a result, in situations where the viscosity of the transmission oil is high and the supply of the transmission oil to the frictional engagement device is delayed, causing a delay in the start of shifting, the transmission command is issued at a lower speed than usual, resulting in The shift is started at an engine speed that is the same as or lower than the normal state, thereby preventing engine overrun.

It is also more preferable to set several types of shift points depending on the number of upshifts or the oil temperature to perform control that corresponds to the length of the shift start time.

[Effects of the Invention] As explained above, according to the automatic transmission control method of the present invention, the gear change command is issued at a lower speed than usual.
Even under conditions where the actual shift start time in the frictional engagement device is delayed, the effect is that engine overrun does not occur.

[Brief explanation of the drawing]

FIG. 1 is a flow chart showing the basic structure of the automatic transmission control method of the present invention, FIG. 2 is a graph showing an upshift pattern for explaining the present invention in detail, and FIG. 3 is an embodiment of the present invention. 4 is a skeleton diagram of the automatic transmission of this embodiment, FIG. 5 is a graph showing the upshift pattern of this embodiment, and FIG. 6 is a flow chart showing the control of this embodiment. FIG. 7 is a graph showing the shift characteristics of the conventional example, and FIG. 8 is a graph showing the upshift pattern of the conventional example. 10... Engine 20... Automatic transmission 30... Control circuit

Claims (1)

[Scope of Claims] 1. A control method for an automatic transmission in which the automatic transmission is controlled to shift using transmission oil based on the driving condition of the vehicle according to a transmission pattern including an upshift pattern, comprising: a transmission oil for the automatic transmission; An automatic transmission control method comprising changing an upshift pattern to a lower speed side when the viscosity of the transmission is equal to or higher than a predetermined value and the number of shifts of the same type after starting the engine is equal to or less than a predetermined number. 2. The automatic transmission control method according to claim 1, wherein the viscosity of the transmission oil is estimated based on the temperature of the transmission oil or the engine water temperature. 3. The automatic transmission control method according to claim 1, wherein the viscosity of the transmission oil is estimated based on the engine rotational speed or the cumulative rotational speed of the output shaft rotational speed of the automatic transmission after the engine is started.