JPS60231056A - Hydraulic shift controlling method in automatic transmission for vehicles - Google Patents

Abstract

PURPOSE:To prevent a shift shock and an undue slip in a frictional engaging element from occurring, by controlling hydraulic pressure to the frictional engaging element so as to cause a revolving speed variation in a rotational element to follow up the desired variation, while keeping the said hydraulic pressure up beyond the minimum one. CONSTITUTION:A revolving speed in a kickdown drum 52 is detected, while duty control over a solenoid valve 106 is compensated so as to cause a variation of this revolving speed to follow up the preset desired variation and then a feeding degree of hydraulic pressure to a hydraulic chamber 366 of a kickdown brake 30 is made to vary to some extent, and the said hydraulic pressure is kept up beyond the preset minimum one varying according to shift time. With this constitution, the occurrence of unforeseen accidents such as prolongation or nonperformance in a speed change due to an undue drop in the hydraulic pressure and ungraspableness for a shift state is solved, whereby a shift shock and an undue slip in a frictional engaging element is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shift hydraulic pressure control method for a vehicle automatic transmission, which supplies an appropriate hydraulic pressure to a frictional engagement element during a shift so that the shift is always carried out in a good condition.

Automatic transmissions for vehicles transmit hydraulic pressure to friction engagement elements such as clutches and brakes to select any rotating element such as a rotating drum or gear. In order to protect equipment 9 and maintain a comfortable ride, pressure oil is gradually supplied to this frictional engagement element according to a predetermined characteristic 11CG. It will be done.

An example of a conventional general automatic transmission for a vehicle will be described with reference to FIG. ing. The torque converter 6 is connected to a pump 8. Turbine 10. Stator 12. It has a one-way clutch 14, and the stator 12 has a one-way clutch 14.
The one-way clutch allows the systator 12 to rotate in the same direction as the crankshaft 4, but is not allowed to rotate in the opposite direction.

The torque transmitted to the turbine 10 is transmitted by the input shaft 20 to a gear transmission 22 disposed at the rear thereof that achieves four forward speeds and one reverse speed.

The transmission 22 includes three sets of clutches 24, 26, 28.
It is composed of two sets of brakes 30, 32, one one-way clutch 34, and one set of Rapigno type planetary gear mechanism 36. The planetary gear mechanism 36 includes a ring gear 38. Long pinion gear 40. Short pinion gear 42. Front sun gear 44. The rear sun gear 462 is composed of a carrier 48 that rotatably supports both pinion gears 40 and 42 and is also rotatable 9, the ring gear 38 is connected to the output shaft 50, and the front sun gear 44 is connected to the kickdown drum 52. Input shaft 20 via clutch 24
The rear sun gear 46 is connected to the input shaft 20 via the carrier clutch 26, and the carrier 48 is connected to the case 16 via the low reverse brake 32 and one-way clutch 34, which are arranged in parallel functionally. and is connected to the input shaft 20 via a four-speed clutch 28 disposed at the rear end of the transmission 22. Note that the kickdown drum 52 is the kickdown brake 30.
It can be fixedly connected to the case 16 by.

The torque that has passed through the planetary gear mechanism 36 is transmitted to the driven gear 64 via the output gear 60 fixed to the output shaft 50, the υ idle gear 62, and the transfer shaft 66 fixed to the driven gear 64, the helical gear 68, the signal is transmitted to a differential gear 72 connected to a drive shaft 70 of the drive wheels.

Each of the above-mentioned clutches and brakes, which are frictional engagement elements, is composed of a frictional engagement device equipped with an engagement piston device or a servo device, etc., and is connected to the bonder 8 of the torque converter 6 to connect to the engine 2. It is operated by hydraulic pressure generated by an oil pump 74 shown in FIG. The hydraulic pressure is selectively supplied to each clutch and brake by a hydraulic control device, which will be described later, according to the operating state detected by various operating state detection devices.
As shown in Table 1, the combination of the clutch and brake operations achieves K, four forward speeds and one reverse speed. In the same table, the ○ mark indicates the stopped state of each clutch or brake, and the ・ mark indicates that the one-way clutch 32 is engaged immediately before the low reverse brake 32 is engaged during gear shifting.
This shows that the rotation of the carrier 48 is stopped by the action of .

Next, an electro-hydraulic control device for achieving the gears shown in Table 1 in the gear transmission 22 shown in FIG. 1 will be described.

The hydraulic control device shown in FIG. 2 includes an oil sump 76, an oil filter 78. The oil discharged from the oil pump 74 via the oil passage 80 is supplied to the torque converter 6 and each clutch 24 , 26 of the transmission 22 .

In order to operate the piston device or servo device of the brakes 30 and 32, the hydraulic pressure supplied to each hydraulic chamber is controlled according to the operating state, and is mainly controlled by the pressure regulating valve 82. Torque converter control valve 84° pressure reducing valve 862 manual valve 88. Shift control valve 90° Rear clutch control valve 92, N-R control valve 94° Hydraulic control valve during gear shifting 96. N-D control valve 98° 1-2 speed shift valve 100. Consists of 2-3 speed and 4-3 speed shift valves 102, 4-speed clutch control valve 104 and three solenoid valves 106, 108, 110. , each element is connected by an oil passage. Among these components, each frictional engagement element 2 is used for changing the gear ratio.
Shift control valve 90.1-2nd speed shift valve 100°2 as a switching valve to switch the oil path to 4.26°28.30.32
- 3rd speed and 4th gear - 3rd speed shift valve 102, 4th speed clutch control valve 104 functions, hydraulic pressure control valve 96°N-R control valve 94 and Yo2
．． and solenoid valve 106 are controlled by electronic controller 112.

Table 1 The above-mentioned solenoid valves 106, 108, and 110 each have the same structure, and are of the non-energized type that controls opening and closing of each orifice 114, 116, and 118 by electric signals from an electronic control device 112. A solenoid valve having a solenoid of 120°122.124. The solenoid has valve bodies 126, 128, 130 disposed inside the solenoid to open and close each oriice 114, 116, 118, and springs 132, 134, 136 to bias the valve bodies in the closing direction.

The electronic control device 112 performs duty control by detecting the operating state of the vehicle and controlling the driving state determining device that determines the opening/closing combination of the solenoid valves 108 and 110, the shift detecting device that detects the start of shifting, etc. Solenoid valve 10
6 operation.

The oil pressure is controlled by stopping and changing the valve opening time by controlling the single pulse current width of the 50 Hz pulse current supplied to the solenoid valve 106, and the solenoid valve 108, 110.
Its input elements include an engine load detection device 138 that detects the throttle valve opening (not shown) of the engine 2 or intake manifold negative pressure, and an engine 20 rotation speed detection device 140, shown in FIG. A rotational speed detection device 142 for the kickdown drum 52, a rotational speed detection device 144 for the driven gear 64 provided to detect the rotational speed of the output shaft 50 corresponding to the vehicle speed, and an oil temperature detection device for detecting lubricating oil temperature. 146, select lever selection position detection device 148 and auxiliary switch selection position detection device 1
It consists of 50 mag.

Pressure oil discharged from the oil pump 74 flows through the oil passage 160.
A pressure regulating valve 829, a manual valve 88, and a pressure reducing valve 86 are guided through the pressure regulating valve 829, the manual valve 88, and the pressure reducing valve 86.

Manual valve 88, equipped with 4 positions of N, R, and P.
When the position is reached, the oil passage 160 is communicated with the oil passages 172 and 174, and as shown in Table 2, the gear transmission device 2
2 achieves the forward operating state of 1st speed to 4th speed, and when it reaches the N position, the oil passage 160 is communicated only with the oil passage 174, the oil passage 172 is communicated with the oil drain port 176, and the gear transmission 22 When the neutral state is achieved and the R position is reached, the oil passage 160
is communicated with the oil passages 178 and 180 to make the gear transmission 22 achieve a reverse operation state (shift stage), and when the gear transmission 22 is in the 2nd position, all oil passages communicating with the manual valve 88 are connected to the oil drain port 176 or the oil drain. The tooth in communication with the passage 182 places the vehicle transmission 22 in a substantially neutral state.

The pressure regulating valve 82 in Table 2 has a pressure receiving surface 184 and 186.
188 and spring leg 190. , received pressure [1f1
When the oil pressure from the oil passage 160 acts on the oil passage 174 through the oil passage 174, the oil pressure in the oil passage 160 is regulated to a predetermined constant pressure (hereinafter referred to as line pressure), and the oil pressure from the oil passage 160 is applied to the pressure receiving surface 186. When acting through the passage 178, the oil pressure in the oil passage 16''0 is regulated to a predetermined value.

The torque converter control valve 84' has a spool 192 and a spring 1'94, and has an oil passage 196 from the pressure regulating valve '82.
The pressure oil guided through the spool 192 is regulated to a predetermined value by balancing the hydraulic pressure acting on the right end pressure receiving surface of the spool 192 through an oil passage 198 formed in the spool 192 and the biasing force of the spring 194. The oil is supplied to the torque converter 6 via an oil passage 200. Note that the oil discharged from the torque converter 6 is supplied to each lubricating section of the transmission via an oil cooler 202.

The pressure reducing valve 86 has a spool 204 and a spring 206, and a pressure receiving surface 208 formed opposite to the spool 204.
, 210 and the biasing force of the spring 206, the hydraulic pressure from the oil passage 160 is adjusted to be reduced to a predetermined value and supplied to the oil passage 212. The pressure regulating oil (reducing oil) guided to the oil passage 212 passes through an orifice 214 to the N-R control valve 94. ``The oil pressure control valve 96 and the orifice 114 of the solenoid valve 106 are reached.

The N-R control valve 94 receives pressure 1iii216, 218°2
20 is formed on a spool 222 and a spring 224.
The hydraulic pressure acting on the pressure receiving surface 2161C and the pressure receiving surface 21
8. Hydraulic pressure and spring 22 due to area difference between 220
The oil pressure in the oil passage 226 is regulated to a predetermined value by the balance with the resultant force of the urging forces No. 4.

The hydraulic control valve 96 has a pressure receiving surface 228,230.

232 is formed on the spool 234 and the spring 23
6, the hydraulic pressure acting on the pressure receiving surface 228 and the pressure receiving surface 23
Hydraulic pressure and spring 23 due to area difference between 0.232
The oil pressure in the oil passage 238 is regulated to a predetermined value by the balance with the resultant force of the urging forces 6 and 6.

Note that the adjusted hydraulic pressure led to the oil passage 226 is used to control the low reverse brake 32 when obtaining the reverse gear stage, and the adjusted oil pressure led to the oil passage 238 is used to control the forward or backward movement of the vehicle. In the stopped state, the front clutch 24
．． Rear clutch 26. Kickdown brake 30. Four-
It controls the reverse brake 32.

The solenoid valve 106 uses a constant frequency pulse current of 50 Hz whose pulse width is changed according to the operating state to control the electronic control unit fl.
The duty is controlled by changing the pulse width and the opening/closing time ratio of the orifice 114 to control the oil pressure in the oil passage 212 downstream of the orifice 214, that is, the pressure received by the N-R control valve 94. It controls the oil pressure acting on the surface 216 and the pressure receiving surface 228 of the oil pressure control valve 96, and the oil pressure supplied to each frictional engagement element is adjusted by this oil pressure change. That is, the above-mentioned oil pressure is regulated based on the relationship between the diameter of the orifice 214 and the diameter of the orifice 114, and the adjusted oil pressure (hydraulic pressure in the oil path 180 or 172) generated in the oil passages 226 and 238 is as follows. The solenoid valve 106 increases and decreases proportionally in response to increases and decreases in the oil pressure.The operation start timing and operation period of the solenoid valve 106 depend on the engine load detection device 138, each rotation speed sensor 140, 142, 144, etc. , electronic control device 1
a shift detection device for detecting the start of a shift built in 12;
It is determined by the electronic control unit 112 in response to electrical signals from etc.

The shift control valve 90 is controlled by a combination of opening and closing of the solenoid valves 108 and 110, and includes three spools 240, 242, 244 and two stoppers 24.
6.248, and the spool 240 has a land 250.
252, annular groove 254, sympathy 254 and land 250
An oil passage 258 communicating with the oil chamber 256 on the left side of the spool 242 is provided, and the spool 242 has lands 26o having different diameters.

262, annular groove 264 and each spool 24o.

The pressing portions 256 and 268 that come into contact with the 244 are provided with a circular groove 270.272° annular groove 2.
74 and sympathy 274 and oil chamber 276 on the right side of land 272
An oil passage 278 is provided that communicates with the. Further, the stopper 246 is interposed between the spools 240 and 242 and is fixed to the casing, and the stopper 248 #'i spool 2
It is inserted at the 42°244 angle and fixed to the casing. The oil passage 172 is always connected to the oil passage 280 via the annular groove 264.
The oil passage 280 communicates with the orifice 116. through the orifice 7 seat 282. Left oil chamber 256 and right oil chamber 2
76 and communicates with the oil chamber 2 between the orifice 118 and the spools 240 and 242 via the orifice 284.
86.

The rear clutch control valve 92 is connected to land 288 and land 2.
A spool 294 provided with a land 290 and an annular groove 292 with a smaller diameter than 88°, and three lands 296, 298° 300 and an annular groove 302.3 with the same diameter as the land 290.
A spool 306 provided with 04 and a spring 308
The land 2 is guided to the oil chamber 310 on the left side of FIG.
When the pressing force of the hydraulic pressure acting on the pressure receiving surface of the land 300 becomes larger than the resultant force of the pressing force of the hydraulic pressure acting on the pressure receiving surface of the land 300 led to the oil chamber 312 on the right side of FIG. The spools 294, 306 are switched to the rightmost position in the figure.

Furthermore, when the right end position is reached, hydraulic pressure acts between the lands 290 and 296, so when the hydraulic pressure in the oil chamber 310 is discharged, only the spool 294 moves to the left end, and then the lands 290 and 296 move to the left end.
The pressing force of the hydraulic pressure acting on the left pressure receiving surface of the oil chamber 3 is
The spool 306 moves to the left when the resultant force of the pressing force due to the hydraulic pressure in the spool 12 and the biasing force of the spring 308 becomes smaller.

The N-D control valve 98 includes a spool 320 provided with lands 314, 316 and an annular groove 318, and a spring 322.
A pressure receiving surface 324 formed on the spool 320,
The spool 320 is selectively switched between the left end position shown in FIG. 2 and the right end position (not shown) depending on the direction of the resultant force of the hydraulic pressure acting on 326 and 328 and the biasing force of the spring 322. be.

The 1-2 speed shift valve 100 has a spool 330 and a spring 332, and a left end pressure receiving surface 334 of the spool 330.
The line pressure is switched between the left end position shown in FIG. 2 and the right end position (not shown) for supplying and discharging line pressure to the pressure receiving surface 334. When the line pressure is discharged, it is positioned at the left end due to the biasing force of the spring 332.

The 2-3 speed and 4-3 speed shift valves 102 and the 4-speed clutch control valve 104 similarly each have a spool 336.338 and a spring 340.342, with each spool 336.3
On the left side of 38 are oil 13s4, 34 to which line pressure is led.
6, oil chambers 348 and 350 are formed on the right side, and each spool can be selectively switched to the left end position shown in FIG. 2 or to the right end position (not shown).

Next, the operation of the automatic transmission with the above configuration will be explained. Since the speed change control of the automatic transmission with the same configuration as the above is already known (see Japanese Patent Application No. 144237/1989, etc.), here,
Taking the 1st->2nd speed shift stage as an example, explanations of other shift stages will be omitted.

First, when the first gear is reached,
Both solenoid valves 108 and 110 are energized, and line pressure led from oil passage 160 to oil passage 172 via manual valve 88 is applied to hydraulic control valve 96. Oil road 238. N-D control valve 98° oil passage 352,! Jya clutch control valve 92. The oil is led to the hydraulic chamber of the rear clutch 26 through the oil passage 354, while branching from the oil passage 238 to the l-speed to 2-speed shift valve 1.
00. The rear clutch 26. Both low reverse brakes 32 are in the engaged state.

When the accelerator is depressed from this state, a shift start signal is sent from the electronic control unit 112 to the solenoid valves 108 and 110, the solenoid valves 108 and 110 are de-energized, and the solenoid valve 110 is maintained in the energized state.

As a result, the spool 240 of the shift control valve 90 moves integrally with the spool 242 to the right in FIG.
40 stops in contact with the stopper 246, and the oil path 1
A line pressure of 72 is applied to the two lands 260 of the spool 242.
−． 262 and is led to an oil passage 362, the line pressure acts on the pressure receiving surface 334 of the 1st-2nd speed shift valve 100 to move the spool 330 to the right end position in FIG. As a result, the line pressure that was led from the oil passage 238 to the 1st-2nd speed shift valve 100 is supplied to the engagement side hydraulic chamber 366 of the kickdown brake 30 via the oil passage 364 as the shift initial oil pressure. As the hydraulic pressure in the hydraulic chamber 366 gradually increases, the rod 368 moves to the left in FIG. 2 against the spring 370 to engage the brake band 30a with the kickdown drum 52, while The hydraulic pressure in the passage 356 is discharged through the oil passage 226, and the low reverse brake 32 is disengaged, thereby achieving a shift to second gear.

As mentioned above, an automatic transmission for a vehicle has a frictional engagement element operated by hydraulic pressure and a rotating element selected by the operation of this frictional engagement element, and hydraulic pressure is supplied depending on the running state of the vehicle. This system automatically selects the frictional engagement element that is used to change the gear ratio between the input shaft, which inputs the rotational power of the engine, and the output shaft, which outputs the rotational power to the drive wheels.
The following problems have occurred depending on the degree of increase in the oil pressure supplied to the frictional engagement element during the shift, that is, from the start of the shift to the end of the shift. In other words, if the feed oil pressure is suddenly increased, the frictional engagement elements are suddenly connected and the shock during gear shifting becomes large, which not only places an excessive load on the automatic transmission and engine, but also causes damage to the vehicle. It was also making me feel worse. On the other hand, if the feed oil pressure rises too slowly, the shift time becomes longer and the frictional engagement element slips excessively, shortening the life of the frictional engagement element and making it difficult to shift. There was a possibility that it would not be possible.

The present invention has been made in view of the above circumstances, and it guarantees the shift function of an automatic transmission regardless of the driving condition of the vehicle, and
The object of the present invention is to achieve appropriate hydraulic pressure to be supplied to frictional engagement elements during gear shifting, and to achieve good gearshifting without causing excessive gearshift impact or slippage of the frictional engagement elements.

A gear shift hydraulic control method according to the present invention that achieves the above object includes an input shaft into which rotational power of an engine is input, an output shaft which outputs rotational power to drive wheels, and an arbitrary rotating element that is operated by hydraulic pressure. a frictional engagement element that switches the gear ratio between the input shaft and the output shaft by selecting the gear ratio, and a detection device that detects rotation whose rotational speed changes during gear shifting and the rotational speed of the element, controlling the oil pressure to the frictional engagement element so that the rate of change in the rotational speed detected by the detection device follows a preset target rate of change, and changing the oil pressure in accordance with the shift time; The feature is that the oil pressure is maintained above the minimum oil pressure.

Hereinafter, an example will be described in which the method of the present invention is applied to the automatic transmission for a vehicle shown in FIGS. 1 and 2.
Since the present invention is carried out in the same manner at each gear stage, the present embodiment will be explained by taking the gear stage from 1st speed to 2nd speed as an example, and the description of the other gear stages will be omitted.

: The flowchart representing this embodiment is shown in FIG.
12 to control the gear shift oil pressure according to the present invention.

゛This embodiment will be explained along the flowchart of FIG.
10 is switched, the initial duty rate a+ of the solenoid valve 106 is determined from the throttle valve opening detected by the detection device 138 and the vehicle speed detected by the detection device 144.
(for example, 42% in this embodiment) is determined. As a result, the solenoid valve 106 is duty-controlled and the oil passage 2
The control oil pressure downstream of the orifice 214 of 12 is adjusted, and the oil passage 238.1-2 speed shift valve 100. Hydraulic chamber 36 of kickdown brake 30 via oil passage 364
6, the shift initial oil pressure Pt is sent to the gear shift initial pressure Pt.

When hydraulic pressure is supplied to the hydraulic chamber 366 as described above, the kickdown drum 366 detects whether or not the first gear is out of synchronization.
The judgment is made based on the rotational speed in step 2 and the vehicle speed. 5. If this desynchronization has not been achieved, the duty rate d of the initial oil pressure P1 is assumed to be too low, and the duty rate is recalculated and increased to achieve the desynchronization.

When the synchronization is achieved as described above, the target rate of change in the rotational speed of the kickdown drum 52, which is predetermined according to each gear stage and running condition, that is, the oil pressure supplied to the hydraulic chamber 366 is optimal. The rate of change in rotational speed that the kickdown drum 52 exhibits when the rotational speed is increasing at a certain degree (a state in which no engagement shock or excessive slipping of the kickdown brake 30 occurs) is determined according to the running state of the main gear. . Then, the rate of change is calculated from the actual rotational speed of the kickdown drum 520, the deviation from the target change rate is calculated, and the duty rate correction amount corresponding to this deviation is calculated to control the duty of the solenoid valve 106. The correction is made to change the degree of hydraulic pressure supplied to the hydraulic chamber 366 of the kickdown brake 30. That is, as shown in FIG. 5(C), the actual rotational speed change rate (dotted line) of the kickdown drum 52, which initially deviates significantly from the target change rate (solid line), is K.
The hydraulic pressure in the hydraulic chamber 366 is feedback-controlled so that it follows the target rate of change and matches or approximates the target change rate at the end, and the kickdown brake 30 is controlled to be engaged at an optimal degree.

Then, the rotational speed of the kickdown drum 52 and the vehicle speed are detected, and a predetermined rotational speed No. in the latter half of the shift at which the rotational speed of the kickdown drum 520 matches or approximates the target rate of change is determined.
(70% of the total rotational speed variation N8 of the kickdown drum 52 in this embodiment) is the actual kickdown drum 520.
It is determined whether the rotational speeds of the kickdown drum 52 match, and if the rotational speed of the kickdown drum 52 is not ND, the above feedback control is continued and the kickdown drum 52 is
The rotational speed of the engine is reduced to zero, that is, the shift to second gear is completed.

Therefore, this shift is performed under feedback control in a good condition without causing shift shock or excessive slippage of the frictional engagement elements.
In feedback control for raising and lowering the oil pressure supplied to the engine, if the oil pressure is lowered too much, the following situation may occur.

That is, since the automatic transmission for a vehicle has various operating states depending on the driving state of the vehicle, in some cases, the feedback control described above may result in a prolonged shift time or a failure in shifting. Specifically, for example, when a vehicle is in a driving state where the accelerator is not depressed much and the foot is removed from the accelerator, the vehicle upshifts to ensure smooth driving. In this case, if you try to make the rotational speed of the rotating element, which naturally decreases with the engine rotational speed, follow the target rate of change, the oil pressure will continue to drop.
There is a possibility that the gear shift will not be completed forever. Also, even if the accelerator is depressed deeply when the oil pressure has dropped significantly as mentioned above, the oil pressure start-up can respond to this.
It is also conceivable that the input data to the electronic control unit 112 may become confused, making it impossible to grasp the gear shift state. In order to eliminate such unforeseen situations, the feedback control flowchart is provided with a subroutine shown in (3) in FIG. That is, in the feedback control as described above, the target change rate and the kickdown drum 52
When calculating the duty rate corresponding to the deviation from the rotational speed change rate of The elapsed time t (shift time) from the start of the shift to the end of the shift is detected, and the lowest oil pressure, that is, the highest duty rate d(t), which is a function of this elapsed time t, is calculated. This calculation is performed using the formula eC, where the initial value (for example, 78% in this embodiment) is di, and the duty change rate (for example, 15%/ in this embodiment) is , As a result, the maximum duty rate d that changes with time t as shown by the dotted line in FIGS. 5(a) and 5(b)
(t) and the minimum oil pressure P(t) corresponding to this maximum duty rate d(t). Then, the duty rate d of the hydraulic pressure actually supplied to the kickdown brake 30 at each point in time during gear shifting is compared with the maximum duty rate d(t), and if d - d(t) > 00, A command is given to the electronic control unit 112 to lower the duty rate (that is, increase the supplied hydraulic pressure), and the duty rate of the electronic control unit 112 is set to the maximum duty rate d(t) or less, so that the hydraulic pressure supplied to the kickdown brake 30 is reduced. K is set so that the oil pressure does not fall below the minimum oil pressure P(t). Therefore, an excessive drop in the oil pressure supplied to the kickdown brake 30 is prevented, and the occurrence of the above-mentioned unexpected situation can be eliminated.

Here, the above-mentioned initial value di and duty rate of change d are set appropriately depending on the characteristics of the engine, automatic transmission, vehicle, etc., and the point is to prevent excessive drop in oil pressure that would lead to the above-mentioned unexpected situation. In order to prevent this problem, any device that can set a maximum duty rate that defines the lower limit of the rise and fall width of the oil pressure by feedback control may be used.

In addition, as shown in Table 1, the kickdown drum 52, which repeatedly stops and rotates in response to the kickdown brake 30, which is repeatedly engaged and disengaged for each gear, is a rotating element to be detected. Therefore, one detection device (sensor) 142 can provide feedback control for all gears, but it is also possible to use a rotating element that operates only in the different gears.

In addition, in this example, an automatic transmission that is set to be compatible with an engine having the following standards for displacement, output torque, etc., is also used for other engines that have different standards, thereby reducing the product cost of the automatic transmission. K to achieve reduction and simplify production management.

It also has a control function that adapts the oil pressure sent to the kickdown brake 30 after the transmission of the gear shift signal, that is, the gear shift initial oil pressure P1, to engines of different standards. That is, if this initial shift oil pressure P does not comply with the engine specifications, for example, when an automatic transmission for a relatively large displacement is combined with a relatively small displacement engine, Compared to automatic transmissions for engines, the working oil pressure (line pressure) of automatic transmissions for large displacement engines is inherently higher, and the engagement force of the frictional engagement element becomes excessive compared to the output torque of this engine, resulting in a shift start signal. As soon as the line pressure is transmitted, the initial oil pressure causes the frictional engagement element to come to a standstill, resulting in a huge shift shock.In addition, in the opposite case, the line pressure is too low. A problem arises in that it takes a long time to shift even if the shift does not start.

In order to solve this problem and realize the use of automatic transmissions for engines with different standards, in the above, the actual rotational speed of the kickdown drum 52 detected is No.
In this case, in the same manner as above, the pre-shift to 2nd gear is completed, and in order to set an appropriate initial shift oil pressure,
At this point, the duty rate d corresponding to the oil pressure P being supplied to the kickdown brake 3o is detected, and the throttle valve opening θt of the engine 2 at that point is detected, and the shift start signal is originally transmitted. Kickdown play
A duty ratio d corresponding to the initial shift oil pressure to be supplied to the key 30 is calculated.

This calculation calculates the total throttle valve opening at A from IcI speed to 2nd speed as shown in FIG.

It is divided into four regions B, C, and D, and a constant k (corresponds to the constant in the region D-A and - to the constant) and a constant! (Area D-
Constants 1I-14 respectively correspond to A) K, and the calculation formula d1=(k 1
9t + l) dt.

The oil pressure based on the duty rate d1 thus obtained is set as the initial oil pressure for the next gear shift, so that the next gear shift matches or approximates the initial oil pressure that should be originally supplied in accordance with the engine. It can be done from In addition to the above calculation method, various methods based on experiments and experience can be used to correct the initial shift oil pressure.
Further, the number of regions and the range of divisions are appropriately set depending on the characteristics of the vehicle engine, automatic transmission, etc.

Further, in the above embodiment, the time point of 70% of the total rotational speed change amount Na of the kickdown drum 52 is taken as the latter half of the shift,
The duty rate d1 of the initial oil pressure P was calculated from the duty rate d2 of the corresponding oil pressure P, or 50% to 100% of the total rotational speed change amount Ns converged to the target change rate by feedback control. If it is within the range of , it is possible to set the duplication ratio d of the initial oil pressure P in the same way.

As explained above, according to the present invention, feedback control is performed so that appropriate oil pressure is supplied to the frictional engagement element during gear shifting, and the oil pressure caused by this feedback is set to be higher than the minimum oil pressure that changes with the gear shifting time. This eliminates the occurrence of unforeseen situations such as prolonged shifting, failure to shift, or inability to grasp the shifting status due to an excessive drop in oil pressure, and prevents shifting shock caused by feedback control and excessive slippage of frictional engagement elements. Thus, it is possible to realize good gear shifting without causing problems such as scratches.

[Brief explanation of drawings]

1 and 2 show an example of an automatic transmission that implements the method of the present invention. FIG. 1 is a schematic diagram of the power transmission section, FIG. 2 is a schematic diagram of the hydraulic control section, and FIG. 3 is a schematic diagram of the hydraulic control section. A flowchart according to an embodiment of the present invention, FIG. 4 is a shift characteristic graph showing the throttle valve opening range, and FIGS. 5(a), (b),
(C) and (d) are graphs showing the duty ratio, the oil pressure supplied to the kickdown brake, the rotational speed of the kickdown drum, and the output shaft torque, respectively, with respect to the shift time. In the drawing, 2 is the engine, 4 is the input shaft, 30 is the kickdown brake, 52 is the kickdown drum, 112 is the electronic control unit, P(t) is the minimum oil pressure, and d(t) is the maximum duty rate. Patent applicant Patent attorney representing Mitsubishi Motors Corporation
Shibu Mitsuishi (1 other person)

Claims (1)

[Claims] An input shaft to which the rotational power of the engine is input, an output shaft to output the rotational power to the driving wheels, and the input shaft and the output shaft can be operated by hydraulic pressure to select an arbitrary rotational element. a frictional engagement element that switches a gear ratio between For a vehicle, the oil pressure to the frictional engagement element is controlled so as to follow a preset target rate of change, and the oil pressure is maintained at a preset minimum oil pressure that changes with shift time. Shift hydraulic control method in automatic transmission.