JPH0154583B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides automatic transmissions for vehicles equipped with a feedback control function that supplies appropriate hydraulic pressure to friction engagement elements during gear shifting, even when the engine is changed to one with different specifications such as output torque and displacement. The present invention relates to a method of automatically correcting and setting an appropriate initial oil pressure to be supplied to a frictional engagement element after transmission of a shift start signal. Automatic transmissions for vehicles supply hydraulic pressure to frictional engagement elements such as clutches and brakes, and
When a rotating element such as a gear is selected, the gear ratio is automatically changed according to the driving condition of the vehicle.This frictional engagement element is used to protect devices and equipment and maintain a comfortable ride. Pressure oil is gradually supplied to the vehicle according to certain predetermined characteristics from the initial hydraulic pressure that is supplied after the transmission of the shift start signal. In recent years, the types of vehicles have diversified according to various uses, and various engines have been used accordingly. However, since the above-mentioned initial oil pressure varies depending on the displacement, output torque, etc. of the engine mounted on the vehicle, many types of automatic transmissions must be prepared depending on the type of engine. In other words, for example, when an automatic transmission for a relatively large displacement engine is combined with a relatively small displacement engine, the hydraulic pressure of the automatic transmission for the large displacement engine will be lower than that of the automatic transmission for the small displacement engine. (line pressure)
is originally large, and the engagement force of the frictional engagement element becomes excessive compared to the output torque of this engine.
There is a problem that as soon as the shift start signal is sent, the frictional engagement element becomes engaged due to the initial oil pressure, resulting in a significant shift shock.In addition, if the opposite occurs, the line pressure is too low. However, there were problems in that the gear change did not start or it took a long time to shift, and it was impossible to use an automatic transmission of a single standard for an engine other than the specified standard. For this reason, in the past, automatic transmissions had to be produced in small quantities and in many varieties, resulting in increased product costs and complicated production management. The present invention has been made in view of the above-mentioned conventional circumstances, and is compatible with various engines in adjusting the initial oil pressure for gear shifting in an automatic transmission equipped with a feedback control function so that appropriate oil pressure is sent to the frictional engagement element during gear shifting. The purpose of this invention is to provide a method for setting the automatic transmission for vehicles to various types of engines, thereby reducing product costs and simplifying production management. The configuration of the present invention that achieves the above object includes an input shaft into which the rotational power of the engine is input, an output shaft which outputs the rotational power to the drive wheels, and an arbitrary rotating element that is actuated by hydraulic pressure. A frictional engagement element that switches the gear ratio between the input shaft and the output shaft, a detection device that detects the rotational speed of the rotating element whose rotational speed changes during gear shifting, and a rotational speed detected by the detection device. In an automatic transmission for a vehicle, the automatic transmission for a vehicle includes a control device that controls hydraulic pressure to the frictional engagement element so that the rate of change follows a preset target rate of change, wherein the rotary element during gear shifting is shifted to a preset speed. The initial oil pressure that should be sent to the frictional engagement element after the transmission of the shift start signal is calculated from the oil pressure that is being fed to the frictional engagement element at the time when the latter rotation speed is reached, and the initial oil pressure is used as the next oil pressure. It is characterized by using the initial oil pressure for gear shifting. Hereinafter, one embodiment of the present invention will be described based on the drawings. First, an example of an automatic transmission for a vehicle that implements the method according to the present invention will be described with reference to FIG. 1 showing a schematic structure thereof. In this embodiment, in order to carry out the method of the present invention, an automatic transmission for a large displacement engine is combined with a small displacement engine 2, and the crankshaft 4 of the engine 2, which is the power source of the vehicle, is a torque converter. 6
It is directly connected to the pump 8. The torque converter 6 includes a pump 8, a turbine 10, a stator 12,
The stator 12 is connected to the case 16 via the one-way clutch 14, and the stator 12 is connected to the case 16 through the one-way clutch 14.
2 rotates 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 to the input shaft 20
The signal is transmitted to a gear transmission 22 disposed at the rear thereof, which achieves four forward speeds and one reverse speed. The transmission device 22 includes three sets of clutches 24, 2
6, 28, two sets of brakes 30, 32, one set of one-way clutch 34, and one set of Ravigneau type planetary gear mechanism 36. The planetary gear mechanism 36 includes a ring gear 38, a long pinion gear 40, a short pinion gear 42, a front sun gear 44, a rear sun gear 46, and both pinion gears 4.
The carrier 48 rotatably supports the ring gear 38 and the ring gear 38.
is connected to the output shaft 50, and the front sun gear 44
Kickdown drum 52, front clutch 2
4, the rear sun gear 46 is connected to the input shaft 20 via the rear clutch 26, and the carrier 48 connects a low reverse brake 32 and a one-way clutch 34, which are arranged functionally in parallel. The input shaft 20 is connected to the case 16 through the transmission 22, and to the input shaft 20 through a four-speed clutch 28 disposed at the rear end of the transmission 22. The kickdown drum 52 can be fixedly connected to the case 16 by a kickdown brake 30. The torque passing through the planetary gear mechanism 36 is transmitted from the output gear 60 fixed to the output shaft 50 to the idle gear 62 to the driven gear 64.
The signal is further transmitted to a differential gear device 72 connected to a drive shaft 70 of the drive wheels via a transfer shaft 66 fixed to the driven gear 64 and a helical gear 68. The clutch and brake, which are frictional engagement elements, each consist of a frictional engagement device equipped with an engagement piston device or a servo device, etc., and are driven by the engine 2 by being connected to the pump 8 of the torque converter 6. It is operated by hydraulic pressure generated by an oil pump 74 shown in FIG. The hydraulic pressure is controlled by a hydraulic control device, which will be described later.
The power is selectively supplied to each clutch and brake according to the operating state detected by various operating state detection devices, and the combination of the operation of each clutch and brake provides four forward and reverse speeds as shown in Table 1. 1
gears are achieved. In the same table, the ○ mark indicates the engagement state of each clutch or brake, and the ● mark indicates that the rotation of the carrier 48 is stopped by the action of the one-way clutch 34 immediately before the lorry berth brake 32 is engaged during gear shifting. It shows. 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 converts oil discharged from an oil pump 74 from an oil reservoir 76 through an oil filter 78 and an oil path 80 into a torque converter.

[Table] 6 and each clutch 24, 26, 2 of the transmission 22
8. In order to operate the piston device or servo device of the brakes 30, 32, the hydraulic pressure supplied to each hydraulic chamber is controlled according to the operating state, and mainly includes a pressure regulating valve 82, a torque converter control valve 84, and a pressure reducing valve 8.
6. Manual valve 88, shift control valve 90, rear clutch control valve 92, N-R control valve 94, hydraulic control valve 96 during gear shifting, N-D control valve 98, 1st-2nd speed shift valve 100, 2nd-3rd speed and 4-3 speed shift valve 10
The components include a 2nd and 4th speed clutch control valve 104 and three solenoid valves 106, 108, and 110, and each element is connected by an oil passage. Among these components, a shift control valve 90 serves as a switching valve for switching oil passages to each frictional engagement element 24, 26, 28, 30, 32 for switching the gear ratio;
A hydraulic control valve during gear shifting in which the 1st-2nd speed shift valve 100, the 2nd-3rd speed and 4th-3rd speed shift valve 102, and the 4th speed clutch control valve 104 function to control the hydraulic pressure supplied to each frictional engagement element. 96, N-R control valve 94 and solenoid valve 106 are controlled by electronic controller 112. Each of the solenoid valves 106, 108, 110 has the same structure, and the electronic control device 1
Each orifice 114,
116, 118 is a closed type solenoid valve when not energized, which controls the opening and closing of solenoids 120, 12.
2, 124, a valve body 12 disposed within the solenoid to open and close each orifice 114, 116, 118;
6, 128, 130 and springs 132, 134, 136 that bias the valve body in the closing direction. The electronic control device 112 includes a driving state determining device that detects the driving state of the vehicle and determines the opening/closing combination of the solenoid valves 108 and 110, a shift detecting device that detects the start of shifting, etc., and performs duty control. The hydraulic pressure is controlled by changing the valve opening time by operating and stopping the solenoid valve 106 and controlling the single pulse current width of the 50 Hz pulse current supplied to the solenoid valve 106.
8,111, and 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, a rotation speed detection device 140 of the engine 2, and a A rotational speed detection device 142 for the kickdown drum 52 shown in FIG. 1, 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 a rotational speed detection device 144 for detecting the lubricating oil temperature. It consists of an oil temperature detection device 146, a select lever selection position detection device 148, an auxiliary switch selection position detection device 150, and the like. Further, the electronic control device 112 is equipped with a flowchart as shown in FIG. After the transmission of the shift start signal, initial oil pressure settings to be sent to these friction engagement elements and feedback control of the feed oil pressure are performed. Pressure oil discharged from the oil pump 74 is guided to a pressure regulating valve 82, a manual valve 88, and a pressure reducing valve 86 via an oil passage 160. The manual valve 88 has four positions: D, N, R, and P. When the manual valve 88 is in the D position, the oil passage 160 is connected to the oil passage 17.
2,174, and causes the gear transmission 22 to achieve the forward operating state of 1st to 4th speeds according to the ON/OFF combination of the solenoid valves 108, 110, as shown in Table 2. When the N position is reached, the oil passage 160 is communicated only with the oil passage 174 and the oil passage 172 is communicated with the oil drain port 176 to achieve a neutral state in the gear transmission 22, and when the R position is reached, the oil passage 16 is communicated with the oil passage 174.
0 to the oil passages 178 and 180 to cause the gear transmission device 22 to achieve a reverse driving state (shift stage),
When in the R position, all oil passages communicating with the manual valve 88 are communicated with the oil drain port 176 or the oil drain passage 182, thereby bringing the gear transmission 22 into a substantially neutral state.

[Table] The pressure regulating valve 82 has a spool 188 and a spring 190, which have pressure receiving surfaces 184 and 186, and the hydraulic pressure from the oil passage 160 is transferred to the pressure receiving surface 184 from 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 pressure receiving surface 1
When the oil pressure from the oil passage 160 acts on the oil passage 86 via the oil passage 178, the oil pressure in the oil passage 160 is regulated to a predetermined value. Torque converter control valve 84 is connected to spool 192
and a spring 194, the pressure oil guided from the pressure regulating valve 82 through the oil passage 196 is connected to the spool 1.
Spool 1 via passage 198 formed in 92
Hydraulic pressure and spring 1 acting on the right end pressure receiving surface of 92
The pressure is regulated to a predetermined value by balancing with the biasing force 94 and supplied to the torque converter 6 via the oil passage 200. Note that the oil exhausted from the torque converter 6 is supplied to each lubricating section of the transmission via an oil cooler 202. The pressure reducing valve 86 is connected to the spool 204 and the spring 2
06, and the balance between the hydraulic pressure and the biasing force of the spring 206 due to the difference in area between the pressure receiving surfaces 208 and 210 formed opposite to each other on the spool 204,
The hydraulic pressure from the oil passage 160 is adjusted to be reduced to a predetermined value and then supplied to the oil passage 212. The pressure regulating oil (reducing oil) guided to the oil passage 212 is fed to the orifice 214.
to the N-R control valve 94, the hydraulic control valve 96, and the orifice 114 of the solenoid valve 106. The N-R control valve 94 has pressure receiving surfaces 216, 218,
It has a spool 222 and a spring 224 in which a pressure receiving surface 220 is formed, and the oil is The oil pressure in the passage 226 is regulated to a predetermined value. The hydraulic control valve 96 has pressure receiving surfaces 228, 230, 2
32 is formed, and a spring 236, the oil is released by the balance between the hydraulic pressure acting on the pressure receiving surface 228, the hydraulic pressure due to the area difference between the pressure receiving surfaces 230 and 232, and the resultant force of the biasing force of the spring 236. The oil pressure in the passage 238 is regulated to a predetermined value. The adjusted hydraulic pressure led to the oil passage 226 is used to control the low reverse brake 32 when obtaining the reverse gear, and the adjusted oil pressure led to the oil passage 238 is used to control the forward movement or stop of the vehicle. In the condition, front clutch 24, rear clutch 2
6. Controls the kickdown drum 30 and low reverse brake 32. The solenoid valve 106 is duty-controlled by the electronic control unit 112 with a constant frequency pulse current of 50 Hz whose pulse width is changed according to the operating state, and the ratio of opening/closing time of the orifice 114 is changed by changing the pulse width. This is to control the hydraulic pressure in the oil passage 212 downstream from the orifice 214, that is, the hydraulic pressure acting on the pressure receiving surface 216 of the N-R control valve 94 and the pressure receiving surface 228 of the hydraulic control valve 96. , adjusts the hydraulic pressure supplied to each frictional engagement element. That is, the orifice 214
The oil pressure is regulated based on the relationship between the diameter of the oil passage 22 and the diameter of the orifice 114.
The adjusting oil pressure (the oil pressure in the oil passage 180 or the oil passage 172) generated at 6,238 increases or decreases proportionally in response to the increase or decrease in the oil pressure. The operation start timing and operation period of the solenoid valve 106 are determined by the engine load detection device 13.
8. In addition to the rotational speed sensors 140, 142, and 144, the speed change detection device that detects the start of a speed change is built into the electronic control device 112, and is determined according to an electrical signal from a flowchart shown in FIG. 3 or the like. . The shift control valve 90 is a solenoid valve 108,1
It has three spools 240, 242, 244 and two stoppers 246, 248, and the spool 240 has lands 250, 252 and an annular groove 25.
4 and the oil chamber 2 on the left side of the same groove 254 and land 250
56, and the spool 242 has lands 260, 262 with different diameters,
An annular groove 264 and pressing parts 266 and 268 that come into contact with each spool 240 and 244 are provided, and the spool 244 has lands 270 and 272 and an annular groove 27.
4 and the oil chamber 2 on the right side of the same groove 274 and land 272
An oil passage 278 communicating with 76 is provided.
Also, the stopper 246 is connected to the spools 240, 242.
A stopper 248 is interposed between the spools 242 and 244 and is fixed to the casing. The oil passage 172 is always communicated with an oil passage 280 via the annular groove 264, and the oil passage 280 is connected to the orifice 116, the left oil chamber 256, and the right oil chamber 27 via the orifice 282.
6 and through an orifice 284 to the orifice 118 and the spools 240, 242.
It communicates with an oil chamber 286 in between. The rear clutch control valve 92 includes a spool 294 provided with a land 288, a land 290 with a smaller diameter than the land 288, and an annular groove 292, and three lands 296, 298 with the same diameter as the land 290.
300, a spool 306 provided with annular grooves 302, 304, and a spring 308, and a land 288 led to the oil chamber 310 on the left side of FIG.
When the hydraulic pressure acting on the pressure receiving surface of the land 300 is larger than the resultant 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. 294,
306 is switched to the right end position in the figure. In addition, since hydraulic pressure acts between lands 290 and 296 at the right end position, when the hydraulic pressure in the oil chamber 310 is discharged, only the spool 294 moves to the left end, and then the hydraulic pressure acting on the left pressure receiving surface of the land 296 When the pressing force becomes smaller than the resultant force of the pressing force due to the hydraulic pressure in the oil chamber 312 and the biasing force of the spring 308, the spool 306 moves to the left. The N-D control valve 98 has a spool 320 provided with lands 314, 316 and an annular groove 318, and a spring 322, and has hydraulic pressure acting on pressure receiving surfaces 324, 326, 328 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 with the biasing force of the spring 322. The 1-2 speed shift valve 100 has a spool 330 and a spring 332, and is shifted between the left end position shown in FIG. 2 and the right end position (not shown) by supplying and discharging line pressure to the left end pressure receiving surface 334 of the spool 330. It can be switched, and when line pressure is supplied to the pressure receiving surface 334, it is moved to the right end by the hydraulic pressure of the same line pressure, and when the line pressure is discharged, it is located to the left end by the biasing force of the spring 332. It is. Similarly, the 2nd-3rd speed and 4th-3rd speed shift valves 102 and the 4th speed clutch control valve 104 are each connected to a spool 33.
6, 338 and springs 340, 342, hydraulic pressure 344, 346 to which line pressure is guided is formed on the left side of each spool 336, 3338, oil chamber 348, 350 is formed on the right side, and each spool has a It can be detected and 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 having the above configuration and the method of setting the initial shift oil pressure according to the present invention will be explained.
Shift control for an automatic transmission having the same structure as above is already known (see Japanese Patent Application No. 144237/1984), and the method of the present invention is the same for each gear.
Taking the 1st->2nd speed shift stage as an example, explanations of other gear stages will be omitted. First, when the first gear is achieved, both the solenoid valves 108 and 110 are energized, and the line pressure is led from the oil passage 160 to the oil passage 172 via the manual valve 88. is the hydraulic control valve 9
6, oil passage 238, N-D control valve 98, oil passage 35
2. The rear clutch control valve 92 is led to the hydraulic chamber of the rear clutch 26 via the oil passage 354;
Branching from the oil passage 238 to the 1st speed-2nd speed shift valve 10
0, the lorry bus brake 32 via the oil path 356
The rear clutch 26,
Both low reverse brakes 32 are in an engaged state. When the accelerator is depressed in this state, the electronic control unit 112 sends the solenoid valves 108, 110
A shift start signal is sent to the solenoid valve 108.
is de-energized, and the solenoid valve 110 is kept energized. As a result, the spool 240 of the shift control valve 90
moves integrally with the spool 242 to the right in FIG. The line pressure is then guided to the oil passage 362, and 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 1st-2nd speed shift valve 100 is connected to the oil passage 238.
The line pressure led to the engagement side hydraulic chamber 366 of the kick-down brake 30 is passed through the oil passage 364.
The rod 368 moves to the left in FIG. When the engine is discharged, the low reverse brake 32 is disengaged and a shift to second gear is achieved. Here, in shifting from the first speed to the second speed,
Kick down brake 30 after transmission of shift start signal
Feedback control of the setting of the initial shift oil pressure P ₁ and the degree of oil pressure feed to the kick-down brake 30 is performed in accordance with the feedback shown in FIG. 3 provided in the electronic control unit 112. That is, the electronic control unit 112 sends a shift start signal and the solenoid valve 10 is activated as described above.
8, 110 is switched, the throttle valve opening detected by the detection device 138 and the detection device 1
Solenoid valve 10 based on the vehicle speed detected by 44
An initial duty rate of 6 is determined. As a result, the solenoid valve 106 is duty-controlled to adjust the control oil pressure downstream of the orifice 214 in the oil passage 212, and the kickdown brake is applied via the oil passage 172, the oil passage 238, the 1st-2nd speed shift valve 100, and the oil passage 364. Shift initial oil pressure to hydraulic chamber 366 of No. 30
It will control P ₁ . Note that since the displacement, output torque, etc. of this automatic transmission and the engine 2 do not originally match, the initial oil pressure P ₁ is sent to the automatic transmission immediately after the vehicle is manufactured, for example, during the first gear shift after manufacturing. The oil pressure is higher than the predetermined initial oil pressure (lower if the specifications of the engine automatic transmission are reversed), and as will be described later, the oil pressure is corrected and set to the predetermined oil pressure in subsequent shifts. When hydraulic pressure is supplied to the hydraulic chamber 366 as described above, it is determined whether or not the first gear is out of synchronization based on the rotational speed of the kickdown drum 52 and the vehicle speed. In addition, if this desynchronization is not achieved, the initial oil pressure _P1 is assumed to be too low, and
The duty rate is recalculated and the initial oil pressure _P1 is increased (see A in Fig. 4) to achieve synchronization. When desynchronization is achieved as described above, the target rate of change in the rotational speed of the kick-down 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 exhibited by the kickdown drum 52 when the rotational speed is rising at a certain degree (in a state where the kickdown brake 30 does not engage or excessively slip, etc.) is determined according to the running state of the high gear. . Then, the rate of change is calculated from the actual rotational speed of the kickdown drum 52, the deviation from the target change rate is calculated, and the duty rate correction amount corresponding to this deviation is calculated to adjust the duty of the solenoid valve 106. Correct the hydraulic chamber 3 of the down brake 30
Change the oil pressure of 66. That is, as shown in FIG. 4, the actual rotational speed change rate (dotted line) of the kick-down drum 52, which initially deviates greatly from the target change rate (solid line), follows the target change rate and eventually changes. The hydraulic pressure in the hydraulic chamber 366 is feedback-controlled to match or approximate the same, and the kick-down brake 30 is controlled to be engaged to the optimum degree. Then, the rotational speed of the kick-down drum 52 and the vehicle speed are detected to determine whether synchronization of the second gear has been completed (shift completion), and if synchronization has not been completed, the above feedback control is repeated. . As described above, the rate of change in the rotational speed of the kickdown drum 52 at the end of the shift matches or approximates the target rate of change that indicates the optimum shift state in this automatic transmission. Total rotational speed variation of drum 52
Based on the oil pressure P ₂ that is being sent to the oil pressure chamber 366 at 70% of Ns), the transmission initial oil pressure P ₁ ' that should originally be sent to the kick-down brake 30 after the transmission of the shift signal in this automatic transmission is determined. For example, the calculation formula d ₁ = (k・θt+l) d ₂ or d ₁ = (k・θt ₊ l)・m・d ₂ d ₁ ; Duty rate corresponding to the original initial oil pressure P ₁ ′; d ₂ ; Corresponding duty rate θ _t ; Throttle valve opening k, l; Constant determined by the throttle valve opening and vehicle speed, respectively. m; Calculated using a proportionality constant, and the oil pressure P ₁ ' found thereby is set as the initial oil pressure for the next shift. . In addition to the calculation method described above, it is also possible to use a method of appropriately setting the initial oil pressure based on experiment or experience. Therefore, the next gear shift is performed with an initial oil pressure that matches or approximates the oil pressure that should originally be supplied than the previous one, so by repeating the above correction control for each gear and each driving state, this automatic gear shift can be performed. The machine can be adapted to engines 2 having different standards such as output torque and displacement. Also,
Even after the original initial oil pressure P ₁ ' is achieved in the next and subsequent gear shifts, the aforementioned feedback control is continued, so that good gear shifts are performed without gear shift shock or excessive slippage. In the above embodiment, the target rate of change is a straight line as shown in FIG. 4, but it is changed at the end of the shift, as shown by the two-dot broken line in the figure, to make the change in the output shaft torque gradual at the end of the shift. You can do it like this. Further, in the above embodiment, the gear position from 1st to 2nd gear was explained, but feedback control is similarly performed for other gear positions, and the kick-down brake, etc., in which hydraulic pressure is supplied at that gear position, etc. The initial oil pressure is corrected by appropriately setting the frictional engagement elements. In addition, in the above embodiment, as shown in Table 1, the rotation of the kick-down drum 52, which is repeatedly stopped and rotated in response to the kick-down brake 30, which is repeatedly engaged and disengaged for each gear, is detected. Since one detection device (sensor) 142 is used as an element, one detection device (sensor) 142 can perform feedback control in all gears, but it is also possible to use a rotating element that operates only in a certain gear. In addition, in the above embodiment, the initial oil pressure P ₁ ' was calculated from the oil pressure P ₂ corresponding to 70% of the total rotational speed change Ns of the kick-down drum 52 as the latter half of the gear shift, but the target change is determined by feedback control. Initial oil pressure P ₁ ' can be found in the same manner as long as it is in the range of 50% to 100% of the total rotational speed variation Ns that converges to the rate. As explained above, according to the present invention, in an automatic transmission for a vehicle equipped with a feedback control function so that appropriate hydraulic pressure is supplied to the frictional engagement element during gear shifting, hydraulic pressure is sent to the frictional engagement element in the latter half of gear shifting. The initial oil pressure for gear shifting to be sent to the frictional engagement element is calculated from the oil pressure being supplied, and this oil pressure is used as the initial oil pressure for the next gear shifting, which eliminates automatic gear shifting that does not conform to the standard engine specifications. The engine can be adapted to this engine through so-called learning control, and automatic transmissions can be used for various engines, thereby reducing product costs and simplifying production management.

[Brief explanation of drawings]

1 and 2 show an example of an automatic transmission that implements the method of the present invention, in which 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.
The figure is a flowchart according to an embodiment of the method of the present invention, and FIG. 4 is a graph showing oil pressure supplied to the kickdown brake, rotational speed of the kickdown drum, and output shaft torque with respect to shift time. In the drawing, 2 is the engine, 20 is the input shaft, 30 is the kickdown brake, 50 is the output shaft, 52 is the kickdown drum, P ₁ and P ₁ ' are the initial oil pressure, and P ₂ is the oil pressure in the latter half of the gear shift.

Claims (1)

[Claims] 1. An input shaft into which the rotational power of the engine is input;
an output shaft that outputs rotational power to the driving wheels; a frictional engagement element that is actuated by hydraulic pressure to switch the gear ratio between the input shaft and the output shaft by selecting an arbitrary rotating element; a detection device for detecting the rotational speed of a rotating element whose rotational speed changes; and a hydraulic pressure applied 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. In the automatic transmission for a vehicle, the automatic transmission for a vehicle is equipped with a control device for controlling a gear, and the gear is shifted from the hydraulic pressure being supplied to the frictional engagement element at the time when the rotating element during gear shifting reaches a preset rotational speed in the latter half of gear shifting. A method for setting an initial oil pressure for a shift in an automatic transmission for a vehicle, characterized in that an initial oil pressure to be supplied to the frictional engagement element is calculated after a start signal is issued, and the initial oil pressure is used as an initial oil pressure for the next gear shift.