JPS61286668A - Direct-coupled mechanism controlling method of hydraulic power transmission device in automatic transmission for vehicles - Google Patents

Abstract

PURPOSE:To make a comfortable drive feeling securable, by reducing the extent of transmission capacity so largely at a time when a velocity ratio goes beyond a reference range value, in a method measuring the velocity ratio in a torque converter at every specified period and controlling the transmission capacity of a direct coupling clutch. CONSTITUTION:A velocity ratio (e) in a torque converter is measured at every specified time and offered for control of the transmission capacity of a direct coupling clutch, but when this velocity ratio (e) exceeds a reference range value, the transmission capacity of the high gear clutch is largely reduced. And, when the velocity ratio is lowered to the reference range value again, such transmission capacity that is somewhat lower than that transmission capacity of the direct coupling clutch at the time of exceeding the reference range value is set there. With this constitution, divergence in a high gear clutch control system is prevented from occurring, thus a comfortable drive feeling is securable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling a direct coupling mechanism of a fluid power transmission device for an automatic transmission for a vehicle.

(Prior art and its problems) In general, vehicles equipped with automatic transmissions use a fluid power transmission device, such as a fluid torque converter, to provide sufficient driving force and a smooth and easy driving feeling with a small number of gears. On the other hand, the actual fuel efficiency is poor due to the fluid slip loss in the torque converter, and the engine speed increases due to the fluid slip, making the engine noisy (it tends to lack quietness).

For this reason, when it is no longer possible to expect the torque amplification function of a torque converter, the torque converter
A direct-coupling clutch mechanism (hereinafter referred to as a "direct-coupling mechanism") called a so-called lock-up mechanism that mechanically couples output members to improve power transmission efficiency has been developed and has already been put into practical use. Since favorable effects can be obtained from improvements in power transmission characteristics and fuel efficiency, it is desirable to operate the direct coupling mechanism from as low a speed as possible. However, if the torque converter is completely directly connected in the low-speed operating range where the engine rotation speed is low, the disadvantage is that the engine torque fluctuations are large, resulting in vibration and noise in the vehicle body, or poor driving performance. be.

Therefore, instead of directly connecting the torque converter in such a low-speed operating range, for example, the rotational speed of the input member and output member of the torque converter should be Calculate the ratio e or slip ratio (=1-e), etc., and in the above low-speed operation range, the rotation speed ratio e is 1 or the slip ratio is 0.
The transmission capacity of the direct coupling mechanism is determined by selecting the optimum transmission capacity from among the multiple transmission capacities (engaging forces) of the direct coupling mechanism while feeding back the actual measured values of the rotational speed ratio e or the slippage ratio to avoid It is possible to control the

However, when such a control method is implemented, the following problems occur. That is, for example, in an embodiment of the present invention to be described later, the transmission capacity is the maximum capacity of the control system when the electromagnetic valve that controls the transmission capacity is off, that is, when the valve is closed.

) is set relatively weakly, the control is performed smoothly and no vibration or noise is generated in the vehicle body, but fuel efficiency deteriorates.On the other hand, in order to improve fuel efficiency, the transmission capacity is set relatively weakly. When set relatively strongly, the rotation speed ratio e sometimes becomes 1.
, or the slip ratio approaches O, or the rotational speed ratio e=1 or the slip ratio becomes 0 instantaneously, causing vibrations and noise in the vehicle body.

This is because no matter how electronic control technology is used, calculating the rotational speed ratio e or slip ratio takes a certain amount of time, including data sampling time, and the feedback system includes mechanical parts such as hydraulic equipment. , there is a physical limit to the response time of the control system that cannot be accelerated beyond a certain value, but if the transmission capacity is set to be strong, the transition to the direction of direct coupling (increasing the transmission capacity) is possible. As the speed increases, there is a delay in control and the rotational speed ratio e or slip ratio exceeds the standard range value, and in order to reflect this result and return it to the standard range value, the transmission capacity is increased more than necessary. Since control is started to decrease the rotational speed ratio e or the slip ratio, the rotational speed ratio e or the slip ratio decreases again to be below the reference range value, which is repeated, and in the worst case, it diverges.

Note that if the response time of the entire control system is shortened, there is no risk of the above-mentioned problem occurring even when the transmission capacity is set to be strong, but in reality, there is a limit to the shortening of the response time.

(Object of the Invention) The present invention has been made in view of the above circumstances, and is an operating range in which it is necessary to accurately control the transmission capacity without causing divergence even when the transmission capacity of the direct coupling mechanism is set to be strong. We control this to the optimum value to suppress vehicle body vibration and noise, as well as improve fuel efficiency and power transmission characteristics.
Another object of the present invention is to provide a direct-coupling mechanism control method for a fluid power transmission device of an automatic transmission for a vehicle, which allows an extremely smooth and comfortable driving feeling to be obtained.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the present invention, predetermined values of predetermined parameter values representing the relative slip amounts of the output member and the output member of the hydraulic power transmission device are set in advance. and a predetermined reference range value, and based on the comparison result, determine the transmission capacity of the direct coupling mechanism for a predetermined period to be implemented from now on,
When the parameter value is above the predetermined reference range value, a reduction region in which the transfer capacity is zero or significantly reduced is set above the predetermined reference range value, and when the parameter value goes below the reduction region. The transfer capacity is set to be smaller than the transfer capacity when the parameter value enters the decreasing region from the predetermined reference range value.

(Example) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an outline of a vehicle automatic transmission to which the present invention is applied, in which the output of an engine E is transmitted from its crankshaft 1 to a torque converter T as a fluid power transmission device, an auxiliary transmission M, and a differential device Df. Sequentially, turn the left and right drive wheels w, w”
and drive them.

The torque converter T includes a pump impeller 2, which is an input member connected to the crankshaft 1, and an input shaft 3 of the auxiliary speed change iJiM.
a turbine wheel 4 which is an output member connected to the input shaft 3;
The stator wheel 5 is connected via a one-way clutch 6 to a stator shaft 5a that is relatively rotatably supported on the stator shaft 5a. As is known, the torque transmitted from the crankshaft 1 to the pump wheel 2 is hydrodynamically transmitted to the turbine wheel 4, and during this time, the torque is amplified.
The stator wheel 5 bears the reaction force.

A pump drive gear 7 for driving the hydraulic pump P shown in FIG. 2 is provided at the right end of the pump impeller 2, and a stator shaft 5a
A stator arm 5b that controls the regulator valve Vr shown in FIG. 2 is fixed to the right end of the stator arm 5b.

A roller-type direct coupling clutch Cd is provided between the pump impeller 2 and the turbine impeller 4 as a direct coupling mechanism capable of mechanically coupling these. To explain this in detail with reference to FIGS. 2 and 3, an annular drive member 9 having a drive conical surface 8 on the inner circumference is spline-fitted to the inner peripheral wall 2a of the pump impeller 2.

Further, an annular driven member 11 having a driven conical surface 10 facing parallel to the driving conical surface 8 on its outer periphery is spline-fitted to the inner circumferential wall 4a of the turbine impeller 4 so as to be slidable in the axial direction. . A piston 12 is integrally formed at one end of this driven member 11, and this piston 12 is slidably engaged with a hydraulic cylinder 13 provided on the wall 4a of the turbine wheel 4.
The internal pressure of the cylinder 13 and the internal pressure of the torque converter T are simultaneously received on both left and right end surfaces.

A cylindrical clutch roller 14 is interposed between the driving and driven conical surfaces 8 and 10, and this clutch roller 14
As shown in the figure, the annular retainer 15 is arranged so that its central axis 0 is inclined at a constant angle θ with respect to the generatrix g of the virtual conical surface Ic (see FIG. 2) passing through the center between the hundred conical surfaces 8 and 10. Retained.

Therefore, when a hydraulic pressure higher than the internal pressure of the torque converter T is introduced into the hydraulic cylinder 13 at a stage when the torque amplification function of the torque converter T is no longer required, the piston 12, that is, the driven member 11 is pushed toward the drive member 9. Ru. As a result, the clutch roller 14 is pressed against the 100-conical surfaces 8 and 10. At this time, when the driving member 9 is rotated in the X direction in FIG. 3 with respect to the driven member 11 by the output torque of the engine E, the clutch roller 14 rotates. Since 0 is tilted as described above, its rotation imparts a relative axial displacement to both members 9.11 that brings them closer together. As a result, the clutch roller 14 has a hundred conical surface 8.10
It bites in between the two members 9 and 11, that is, the pump wheel 2 and the turbine wheel 4 to be mechanically connected. Even during such operation of the direct coupling clutch Cd, if the output torque of the engine E exceeds the coupling force and is applied between the two wing wheels 2 and 4, the clutch roller 14 will be This causes slippage, and the torque is divided into two parts, with part of the torque being transmitted mechanically through the direct coupling clutch Cd, and the remaining torque being transmitted hydrodynamically from the pump wheel 2 to the turbine wheel 4. The ratio of the former torque to the latter torque changes depending on the degree of slippage of the clutch roller 14.

If a reverse load is applied to the torque converter T in the operating state of the direct coupling clutch Cd, the rotational speed of the driven member 11 becomes higher than the rotational speed of the driving member 9. The clutch roller 14 rotates in the Y direction in FIG. 3, and the clutch roller 14 rotates in a direction opposite to the previous direction, thereby applying a relative axial displacement to the members 9 and 11 to separate them from each other. As a result, the clutch roller 14 is released from being wedged between the 100-conical surfaces 8 and 10, and enters an idling state. Therefore, the turbine wheel 4
The transmission of the reverse load from to the pump wheel 2 takes place only hydrodynamically.

When the hydraulic pressure of the hydraulic cylinder 13 is released, the piston 12 receives the internal pressure of the torque converter T and retreats to its initial position, so that the direct coupling clutch Cd becomes inactive.

Referring again to FIG. 1, the mutually parallel persons of the auxiliary transmission M,
A first speed gear train G1, a second speed gear train G2, a third speed gear train Gl, a fourth speed gear train G4, and a reverse gear train Or are provided in parallel between the output shafts 3.16. The first speed gear train G1 includes a drive gear 17 connected to the input shaft 3 via a first speed clutch C1, and a one-way latch C that meshes with the gear 17 and connects to the output shaft 16.

and a driven gear 18 that can be connected via. The second speed gear train G2 consists of a driving gear 19 that can be connected to the input shaft 3 via a second speed clutch c2, and a driven gear 20 that is fixed to the output shaft 16 and meshes with the gear 19. The third speed gear train G3 consists of a driving gear 21 fixed to the input shaft 3, and a driven gear 22 connected to the output shaft 16 via a third speed clutch C3 and capable of meshing with the gear 21. Also the fourth
The speed gear train G4 is connected to the input shaft 3 via the fourth speed clutch C4.
The drive gear 24 is connected to the output shaft 16 via a switching clutch Cs and meshes with the gear 23. Further, the reverse gear train Gr includes a driving gear 25 provided integrally with the driving gear 23 of the fourth speed gear train G4, a driven gear 26 connected to the output shaft 16 via the switching clutch Cs, and both gears 25. .26 and an idle gear 27 that meshes with the gear. The switching clutch Cs is
By shifting the selector sleeve S of the clutch Cs, which is provided between the driven gear 24 and the idle gear 27 of the fourth speed gear train G4, to the forward position on the left or the reverse position on the right in FIG. Driven gear 24 and idle gear 27
can be selectively connected to the output shaft 1B. One-way clutch Co transmits only drive torque from engine E to drive wheels w, w', and does not transmit torque in the opposite direction.

Thus, when the selector sleeve S is held in the forward position as shown in FIG. A gear train G1 is established, and torque is transmitted from the input shaft 3 to the output shaft 16 via this gear train G1. Next, the first
While the speed clutch C1 remains connected, the second speed clutch C2
When connected, the drive gear 19 is connected to the input shaft 3 to establish the second speed gear train G2, and torque is transmitted from the input shaft 3 to the output shaft 16 via this gear train G2. At this time, the first speed clutch C1 is also engaged, but due to the action of the one-way clutch Co, the first speed is not established, but the second speed gear train G2 is established, which is connected to the third and fourth speeds. The same goes for when. Release the second gear clutch C2 and apply the third gear clutch C3.
When the driven gear 22 is connected to the output shaft 16, the third speed gear train G3 is established, and when the third speed clutch C3 is released and the fourth speed clutch C4 is connected, the driven gear 22 is connected to the output shaft 16 and the third speed gear train G3 is established. 23 is connected to the input shaft 3 and the fourth speed gear train G4
is established. Furthermore, if the selector sleeve S of the switching clutch Cs is moved to the right in FIG. The reverse gear train Gr is established, and the output shaft 1 is connected from the input shaft 3 to the output shaft 1 via this gear train Gr.
Reverse torque is transmitted to 6.

The torque transmitted to the output shaft 16 is transmitted from the output gear 28 provided at the end of the shaft 16 to the large diameter gear Do of the differential device Df. One end of a speedometer cable 30 is fixed to the gear 29 meshing with the gear Ds fixed to the gear DG, and the speedometer 3 is connected to the other end of the speedometer cable 30 via a magnet 31a of a vehicle speed detector 31.
2 is connected, and the speedometer 32 is connected to the gear Ds, 29
and a cable 30 to display the vehicle speed.

The vehicle speed detector 31 includes the magnet 31a and a reed switch 31b, for example, which is driven by the magnet 31a.
1b is opened and closed, and on and off signals accompanying this opening and closing are supplied to an electronic control device 33, which will be described later.

FIG. 2 shows a hydraulic control circuit for a vehicle automatic transmission to which the present invention is applied.

In the figure, a hydraulic pump P whose suction port is connected to an oil tank R is connected via an oil path 300 to an inlet port 60a of a regulator valve Vr, a biloft pressure introduction boat 60b, and a boat 70 of a manual shift valve (hereinafter simply referred to as a manual valve) Vm.
b and the inlet boat 80a of the governor valve Vg, respectively. The boats 70a and 70c of the manual valve Vm are connected to the boat 9 of the servo piston 90 via oil passages 301 and 302, respectively.
At 0C290b, the boat 70C further connects the manual valve Vm boat 70d, the pressure reducing valve 270 inlet boat 270a, and the throttle valve Vt boat 100a via the oil passage 303.
, the boat 70e connects the manual valve Vm via the oil passage 304.
boat 70g, timing valve 210 boat 210d
, are connected to the boat 170a of the first accumulator 170 and the second speed clutch C2, respectively. In addition, the manual valve Vm boat 70f has a throttle 350 and a one-way valve 38 in the middle.
The boat 70h connects the oil passage 31 with a throttle 359 and a one-way valve 383 in parallel to the second shift valve 130b via an oil passage 305 connected in parallel with the oil passage 305.
3 to the first speed clutch C1, respectively. The two inlet ports 400a and 400b of the flow rate regulating valve 400 are connected to the core oil passage 313 through an oil passage 307 provided with a throttle 369.
is connected, and one outlet bow of the flow rate regulating valve 400) 4
00d is connected to the bow 120b of the first shift valve V1 via an oil passage 307a. A throttle 370 is provided between the first inlet boat 400a of the flow rate regulating valve 400 and the oil passage 307.
is interposed.

The boat 70i of the manual valve Vm is connected to the boat 90a of the servo piston 90 via an oil passage 308, and the boat 70i of the manual valve Vm is connected to the boat 210 of the timing valve 210 via an oil passage 309.
e, the boat 70m is connected to the boat 190a of the second accumulator 190 and the fourth speed clutch C4 via the oil passage 310 to the boat 70n of the manual valve Vm, and the second shift valve V.
The first control valve 160 is connected to the second boat 130d and the second boat 160b of the first control valve 160, respectively. A throttle 356 and a one-way valve 381 are arranged in parallel with each other between the oil passage 310 and the boat 130d of the second shift valve V2.

Throttle opening responsive valve Vt boats 100b and 10
0c is connected to each boat 170b, 190b of the first to third accumulators 170, 190, 180 via an oil passage 311.
, 180b, boat 22Of of modulator valve 220,
Port 230C1 of on-off valve 230 Flow rate adjustment valve 40
0 boat 400c, first control valve 160 boat) 16
0a, and the boat 100b of the throttle opening responsive valve Vt, which is connected to the boat 200a of the second control valve 200, respectively.
A throttle 352 is interposed between the oil passage 311 and the oil passage 311 . The boat 100d of the throttle opening response valve Vt is connected to the boat 130g of the second shift valve v2 and the drain EX via an oil passage 312, and a throttle 353 is interposed between the oil passage 312 and the drain EX. be done. The boat 110a of the third control valve 110 is connected to the first shift valve ■1 via an oil passage 315.
is connected to the boat 120a and the drain EX, respectively, and a throttle 354 is interposed between the oil passage 315 and the drain EX.

120c and 120d of the first shift valve v1 are connected to the boats 130a and 130c of the second shift valve v2 via oil passages 316 and 317, respectively, and 120e is the oil passage 31
8 to the bow) 160c of the first control valve 160 and the drain EX, respectively; and the oil passage 318 and the drain EX.
A diaphragm 355 is interposed between the two. Second shift valve ■
The second port 130e is connected to the port 200c of the second control valve 200 and the drain EX via an oil passage 319, and a throttle 357 is interposed between the oil passage 319 and the drain EX. The port 130f of the second shift valve 2 is connected to the port 200b of the second control valve 200 via an oil passage 320 in which a throttle 358 and a one-way valve 382 are connected in parallel.
, are connected to the port 180a of the third accumulator 180 and the third speed clutch C3, respectively. Note that a throttle 35 is installed on one of the two EX boats of the second shift valve v2.
6a is interposed.

The port 120f of the first shift valve 1 is connected to the inlet port 140a of the first solenoid valve 140 via an oil passage 340, and the oil passage 340 is connected to the pressure reducing valve 270 via an oil passage 341 provided with a throttle 361. Connected to exit boat 270b. The port 130h of the second shift valve v2 is connected to the inlet boat 150a of the second solenoid valve 150 via an oil passage 322a, and the oil passage 322a is connected to the oil passage 3 through a throttle 362.
22, and this oil passage 322 is connected to the outlet boat 80b of the governor valve Vg.

Each valve body 141. of the first and second solenoid valves 140.150.
151 is the deenergization (off) of solenoids 142 and 152, respectively.
When pressed by the spring force of springs 143 and 153, the inlet ports 140a and 150a are closed, and the solenoid 1
42, 152 is biased (on), the entrance boat 140a is attracted against the spring force.

150a is opened. That is, the first and second solenoid valves 14
0 and 150 are closed when the solenoids 142 and 152 are deenergized, and opened when the solenoids are energized.

The outlet boat 60c of the regulator valve Vr is connected to the port 210a of the timing valve 210 and the ON-
230d of the off valve 230, respectively. The port 210b of the timing valve 210 has a throttle 371 in the middle.
The port 210C is connected to the bow) 220a of the modulator valve 220 via an oil passage 327, and the port 210C is connected to the bow) 220a of the modulator valve 220 via an oil passage 327.
Of is connected to the oil passage 501 through an oil passage 501a provided with a throttle 375 in the middle. The port 220b of the modulator valve 220 is an oil passage 3 in which a throttle 372 is provided in the middle.
26a to the oil line 326, bow) 220c
is turned on through an oil passage 353 with a throttle 373 in the middle.
The ports 230b and 220e of the off valve 230 are respectively connected to an oil passage 322 having a throttle 366a in the middle. Port 230a of on-off valve 230 is connected to oil passage 326
In addition, the port 230e is an oil passage 5 with a throttle 374 in the middle.
It is connected to the oil passage 334 via 01.

The inlet bow) 240a of the third solenoid valve 240 is the throttle 367
It is connected to the oil passage 326 via. This third solenoid valve 2
When the solenoid 242 is deenergized (off), the valve body 241 of 40 is pressed by the spring force of the spring 243, and the valve body 241 of the inlet boat 2
40a is closed, and when the solenoid 242 is energized (on), it is attracted against the spring force and opens the inlet boat 240a. That is, the third solenoid valve 240 is closed when the solenoid 242 is deenergized, and opened when the solenoid 242 is energized.

The bow)Ta of the torque converter T is connected to the oil passage 325 through the oil passage 334 provided with the throttle 368, the bow) Tb is connected to the oil passage 326, and the port Tc is connected to the pressure holding valve 2 through the oil passage 335.
50 inlet boats 250a. This pressure holding valve 2
The 50 biloft pressure introduction boats 250b are connected to the upstream side of the throttle 366a of the oil passage 322 via an oil passage 336, and the outlet boat 250c is connected to the drain EX via an oil passage 337 and an oil cooler 260, respectively. Each drain EX is connected to an oil tank R, respectively.

Each solenoid valve 1/1 of the first to third solenoid valves 140, 150, 240
Noids 142, 152, 242 are signal lines 142a,
It is connected to the electronic control unit 33 via 152a and 242a, respectively. The electronic control device 33 operates the first and second electromagnetic valves 140 and 140 according to a predetermined shift map based on input signals from the vehicle speed detector 31, engine speed detector 34, gear position detector 35, etc. 150 to control the first
Engagement/disengagement of the clutches C1 to C4 (off FI)
M) to perform speed change control. In addition, the electronic control device 33
The operator of the torque converter T actually measures a predetermined parameter value representing the relative slip amount of the output member, for example, the speed ratio e, and compares the measured value e with a predetermined reference value, and based on the comparison result, , determines the engagement force (transmission capacity) of the direct coupling clutch Cd, and controls the third electromagnetic valve 240 to control the engagement force of the direct coupling clutch Cd.

The operation of the above-mentioned hydraulic circuit will be explained below.

The hydraulic pump P sucks in and pressurizes the hydraulic oil in the oil tank R, regulates the pressure to a predetermined pressure (hereinafter referred to as line pressure Pl) with a regulator valve Vr, and then pumps it to the oil path 300. The stator arm 5b (see Fig. 1) is in contact with the spring receiver 61 of the regulator valve Vr, and when the reaction force of the stator wheel 5 of the torque converter T exceeds a predetermined value, the spring 62 is compressed and the hydraulic pump P Increase the discharge pressure. Such hydraulic control is detailed in Japanese Patent Publication No. 45-30861. A part of the hydraulic oil whose pressure is regulated by the regulator valve Vr is sent into the torque converter T through an inlet oil passage 334 having a throttle 368, and after pressurizing the inside thereof to prevent cavitation, the pressure holding valve 250, Tank R via oil cooler 260
is refluxed to. In the pressure holding valve 250, as the vehicle speed U increases, the spool 251 moves to the right in the figure against the spring 252 due to the governor pressure Pc, and the internal pressure of the torque converter T is released to the oil tank R. That is, the pressure holding valve 250 functions to lower the internal pressure of the torque converter T in proportion to the vehicle speed U.
Since the spool 251 is operated by the differential pressure with the governor pressure PG, the transmission capacity of the direct coupling clutch Cd increases, and the maximum value of the transmission capacity of the direct coupling clutch Cd is increased on the high speed side.

The manual valve Vm is switched by manual switching operation of the shift lever, and includes P (parking), R (reverse), N (neutral), D4 (4-speed forward automatic transmission), D3 (3-speed forward automatic transmission except TOP), 2 (2ND hold), and an operation mode corresponding to each shift position is arbitrarily selected.

When the spool 71 of the manual valve Vm is in the illustrated N position, the bow 70b connected to the oil passage 300 is blocked by the spool 71 of the manual valve Vm, and the other bows 70a, 70c~? On is connected to the drain EX, and all four clutches C1 to C4 of 1st to 4th gears are placed in a disengaged state, so the engine torque is applied to the driving wheels W, W'' (see Figure 1). ) is not transmitted.

When the spool 71 of the manual valve Vm moves one frame to the left from the illustrated position and is at the D4 position, both the oil passages 302 and 313 communicate with the oil passage 300, and pressure oil is supplied to the oil passage 30.
5,304 communicate with each other. Further, the oil passage 309 is communicated with the oil passage 310, but is isolated from the drain EX and the oil passage 308, respectively, and the oil passage 301 continues to communicate with the drain EX. As a result, in the D4 position (range), the servo piston 90 for moving the selector sleeve S (see Fig. 1) receives the line pressure P2 in its spring chamber 92, and the spool 91 also receives the line pressure P2 hydraulically. The selector sleeve S is held in the position shown in FIG. 1 by a shift fork 39 fixed to one end of the spool 91. As a result, the fourth speed driven gear 24 is placed in an engaged state with the switching clutch Cs, and the reverse driven gear 26 is placed in a freely rotatable state.

Even if the spool 71 of the manual valve Vm further moves one frame to the left from this state and is placed at the D3 position, the oil passage 310 remains blank.
The connection relationships of the respective oil passages connected to the manual valve Vm do not change except that they are connected to the drain EX via 70m and 70n. These 2. D3. At the D4 position, pressure oil is sent to the throttle opening responsive valve Vt via the oil passage 303.

The throttle opening response valve Vt is a parameter representing the load of the engine E, and is proportional to the amount of depression of the throttle pedal (not shown), that is, the valve opening of the throttle valve (not shown) provided in the intake system of the engine E. The left spool 101 is moved to the left by receiving the displacement of the cam 104 which rotates counterclockwise from the illustrated position via the spring 103, and the port 10 is moved to the left.
0a to the open side, and the discharge pressure of its output port 100c,
Bo zoob plus spool 10 through aperture 352
1 to the right to drive the port 100a to the closing side, and generates a pressure (hereinafter referred to as throttle pressure Pt) in the output oil passage 311 that is proportional to the opening degree of the throttle valve. In addition, the counterclockwise rotation of the cam 104 moves the right spool 102 to the left and connects the boat 100d and the drain EX.
The transmission is continuously throttled to reduce the shift shock when kicking down from 3rd gear (3RD) to 2nd gear (2ND).

Cam 113 of third control valve 110 interlocking with cam 104
rotates counterclockwise in accordance with the opening degree of the throttle valve to move the spool 111 to the left against the spring force of the spring 112, continuously restricting the communication between the boat 110a and the drain EX, and Alleviates the shift shock when kicking down from TOP to 3RD. Further, the throttle pressure pt is applied to the flow rate adjusting valve 400 via the oil passage 311.
400c to control the valve 400. That is, when the flow rate adjustment valve 400 is in the state shown in the figure, the flow rate adjustment valve 400 passes only through the first inlet port 400a provided with the throttle 370 from the oil passage 307, and from the outlet boat 400d through the oil passage 307a to the first shift valve 1. hydraulic pressure is sent to 120b,
Furthermore, when the throttle pressure pt increases and overcomes the force of the spring 402, the spool 401 moves to the left and passes through both the first and second inlet ports 4'OOa and 400b, from the outlet boat 400d to the oil passage 307a. Increase the amount of pressure oil supplied to the clutches, and when the throttle valve opening is small, both clutches will engage (this will cause the two clutches to engage together, and energy will be consumed in both clutches, causing the vehicle speed to drop below the previous speed). In order to prevent this, the system prevents the next clutch from being engaged until one clutch is completely disengaged. For example, this prevents the next clutch from being engaged until the clutch is completely disengaged. Alleviate the shock.

The discharge oil of the hydraulic pump P is at the inlet bow of the governor valve Vg) 80
a, the governor valve Vg is rotated by its own shaft 82 at a speed proportional to the vehicle speed by a gear 81 meshing with the large-diameter gear DG shown in FIG. A pressure proportional to (hereinafter referred to as governor pressure Pc) is output.

When the first shift valve (1) is in the first position shown, the input oil passage 307a is connected to the output oil passage 316, and another output oil passage 317 is connected to the drain EX via the oil passage 318. The valve body 121 of the first shift valve v1 is shifted to the first position by the spring 122. The first shift valve V1 has a line pressure P introduced from the pressure reducing valve 270 through the oil passage 341, the throttle 361, and the oil passage 340 into the chamber 120A, which its right end face faces.
With the hydraulic pressure reduced to a pressure lower than R, it can be moved to the left against the spring force of the spring 122 to take the second position, and when it is in the second position, the output oil passage 316 is drained through the oil passage 315. EX, and another output oil passage 317 is separated from the oil passage 318 and connected to the input oil passage 307a.

When the first shift valve ■1 is in either the first or second position, the oil passage 313 is connected to the first speed (LOW') clutch C1, so that the manual valve Vm is in the D3 or When in the D4 position, the first speed clutch C1 is always pressurized and engaged. The spool 121 of the first shift valve v1 is controlled by a first solenoid valve 140, and when the solenoid valve 140 is closed, the pressure introduced into the chamber 120A causes the second position to be set to the second position, and when the solenoid valve 140 is opened, the spring 122 is moved to the second position. takes the first position.

When the second shift valve v2 is in the first position shown, it blocks the input oil passage 316, connects the output boat 130d to the drain EX, connects the input oil passage 317 to the output oil passage 305,
Further, the output oil passage 320 is connected to the drain EX via the oil passage 312. The spool 131 of the second shift valve ■2 is the spring 1
32 to the first position. This shift valve■2
is moved to the left against the spring force of the spring 132 by the governor pressure Pe introduced from the boat 130h into the chamber 130A facing the right end surface of the spool 131 through the oil passage 322, the throttle 362, and the oil passage 322a, and is moved to the second position. and when in the second position, disconnect the output capo 130d from the drain EX and connect it to the input oil passage 316, connect the output oil passage 305 to the drain EX via the oil passage 319, The remaining output oil passage 320 is separated from the oil passage 312 and is connected to the input oil passage 3.
Switch connection to 17.

The spool 131 of the second shift valve v2 is controlled by a second solenoid valve 150, and when the solenoid valve 150 is closed, the second position is set by the governor pressure Pc introduced into the chamber 130A, and when the solenoid valve 150 is opened, the spool 131 is set to the second position by a spring. 132 to assume the first position.

Further, the second shift valve v2 is particularly provided with a click motion mechanism 133 so that its switching operation is performed in an on-off manner. This click motion mechanism 133
is the governor pressure Pc even when the second solenoid valve 150 is closed.
The spool position of the shift valve V2 is limited to either the first or second position in response to a change in the shift valve V2.

Now, as long as the engine E is rotating, the hydraulic oil pressurized by the hydraulic pump P is sent to the governor valve Vg.
g, the pressure is regulated as a signal pressure proportional to the vehicle speed U and guided to the chamber 130A of the second shift valve v2, and the pressure reducing valve 27
The pressure is reduced at 0 and guided to the chamber 120A of the first shift valve v1. When the manual valve Vm is in the 04 (or D3) position, the solenoids 142 and 152 of the two solenoid valves 140 and 150 are energized together to maintain these two shift valves V1 and V2 in the first switching position shown. All you have to do is open the valve. As a result, each clutch 02-C of 2nd speed to 4th speed
I4 is not pressurized, only the first speed clutch C1 is engaged under pressure, and the first speed reduction ratio is established. Since this first speed generally covers a low speed region, the governor pressure PG itself is low pressure in this low speed region, and is discharged from the second solenoid valve 150 to the oil tank R via the throttle 362. The loss flow rate of the pressure oil caused by this process is correspondingly small, making it economical. This point is particularly advantageous when the pressure of the entire system must be maintained considerably higher than the normal pressure level (line pressure Pl), such as when starting at a stall (vehicle speed -0).

Next, the solenoid 152 of the second solenoid valve 150 is energized to maintain the solenoid valve 150 in the open state, and the solenoid 142 of the first solenoid valve 140 is deenergized to keep the solenoid 150 open.
When the valve 0 is closed, hydraulic pressure reduced by the pressure reducing valve 270 is generated in the chamber 120A of the first shift valve v1, and this causes the spool 12 of the shift valve v1 to resist the spring force of the spring 122.
1 moves to the left. Due to this leftward movement of the spool 121, the oil path 3
07a is connected to the oil passage 305 via the oil passage 317, and the oil passage 305 is connected to the port of the manual valve Vm when in the D4 position.
? Of, to the oil passage 304 through the notch 71a of the spool 71 and the port 70g, and when in the D3 position, the bow) 70
f, annular groove 71b of spool 71;

are respectively connected to the oil passages 304 via ports 70e,
The speed clutch C2 is engaged under pressure. Therefore, D4 or D
In the 3rd position, the first gear clutch C1 and the second gear clutch C2
are engaged under pressure. However, as shown in FIG. 1, a one-way clutch Co is interposed between the first speed driven gear 18 and the output shaft 16, which transmits torque only in the direction of the driving torque from the engine E. A speed reduction ratio is established.

Next, with the solenoid 142 of the first solenoid valve 140 deenergized and the solenoid valve 140 closed, the second solenoid valve 150 is opened.
When the solenoid 152 is deenergized and the solenoid valve 150 is closed, the governor pressure PG at that time is generated in the chamber 130A of the second shift valve v2, and the resistance force by the spring 132 and the click motion mechanism 133 is reduced to the governor pressure. Only when the left power generated by the PG exceeds the left power, the spool 131 moves to the left and assumes the second position. Due to this leftward movement of the spool 131, the oil passage 305 is connected to the drain EX via the oil passage 319, and the engagement of the second speed clutch C2 is released, and at the same time, the oil passage 320 is connected to the oil passage 317, which is a hydraulic pressure source. 3rd gear clutch C3
are engaged under pressure. At this time as well, the first gear clutch C1 is pressurized and engaged, but due to the action of the one-way clutch Co, the third gear clutch
A speed reduction ratio is established.

Next, the solenoid 152 of the second solenoid valve 150 is held in a de-energized state, and the solenoid 14 of the first solenoid valve 140 is held in a de-energized state.
2 is energized again to open the solenoid valve 140, the spool 121 of the first shift valve v1 moves to the right and returns to the position shown, connecting the oil passage 317 to the drain EX via the oil passage 318. The engagement of the third speed clutch C3 is released, and at the same time, the oil passage 316 is connected to the hydraulic pressure source 307a, and pressure oil is supplied to the oil passage 310.

The oil passage 310 is connected to the oil passage 309 via ports 7Qm and 70k of the manual valve Vm when in the D4 shift position,
Fourth speed clutch C4 is engaged under pressure. At this time as well, the first speed clutch C1 is pressurized and engaged, but as described above, the reduction ratio of the fourth speed is established by the action of the one-way latch CO. In this manner, automatic gear shifting from first to fourth gears is performed.

Each reduction ratio of these 1st speed to 4th speed and the 1st speed. The relationship between the second electromagnetic valves 140 and 150 and the respective solenoids 142 and 152 is shown in Table 1.

On the other hand, the hydraulic pump P discharged from the regulator valve Vr
A part of the working oil pressure flows into the torque converter T through an oil passage 334 provided with a throttle 368 to increase its internal pressure and is sent to the timing valve 210 and the on-off valve 230. The timing valve 210 has chambers 210A and 210B introduced with oil pressure to be applied to the second speed clutch C2 and fourth speed clutch C7I, respectively, and the spool 211 has a reduction ratio for the second speed or fourth speed established. Sometimes the spring 21
2 to the left against the spring force of 2 to the 2nd switching position, and to the 1st switching position.
When the reduction ratio of speed or third speed is established, the spring 21
The spring force of 2 moves the spool 212 to the right to assume the first switching position shown.

When the timing valve 210 is in either of these two switching positions, it connects the input oil passage 325 to the output oil passage 327 and also connects the drain oil passage 32 of the modulator valve 220.
1 to the drain EX, but during the transition to both switching positions, the output oil passage 327 is cut off from the input oil passage 325, and the drain oil passage 321 of the modulator valve 220 is cut off from the drain EX. The oil pressure in the output oil passage 327 of the timing valve 210 is input to the modulator valve 220, modulated, and output to its output oil passage 353. The modulator valve 220 modulates the hydraulic pressure using the governor pressure Pc and the throttle pressure pt to create the engagement force of the direct clutch CdO.
22, 311, governor pressure Pc, throat/nottle pressure P
t has been introduced, and these two pressures and the spring 222
The spring force moves the spool 221 to the left toward the valve opening side, and the feedback pressure of the output oil passage 326 is applied to the oil passage 326a and the throttle 37.
2, the governor pressure P is received on the left end surface of the spool 221 through
c, the spool 221 is configured to move to the right toward the valve closing side against the throttle pressure pt and the spring force of the spring 222. As a result, a pressure proportional to the vehicle speed U and the opening degree of the throttle valve appears in the output oil passage 353.

When the pressure output from the modulator valve 220 becomes too high, the spool 221 of the modulator valve 220 moves to the right in the figure against the resultant force of the governor pressure PC, throttle pressure pt, and spring 222 due to feedback pressure, causing the pressure to increase. is drained to drain EX via the timing valve 210. And when the gear is not changing, the timing valve 21
The drain oil passage 321 of the modulator valve 220 is always connected to the drain EX through the is not drained anywhere.

The reason for doing this is that it is necessary to control the engagement force (transmission capacity) of the direct coupling clutch CdO only by the third solenoid valve 240, and to prevent the engagement force of the direct coupling clutch Cd from decreasing excessively during gear shifting. be. That is, during a gear shift, the line pressure Pβ decreases due to the movement of the accumulator in connection with the gear shift, and the throttle pressure pt also decreases momentarily. For this reason, the spool 221 of the modulator valve 220 moves to the right in the figure, and if the drain oil passage 321 is connected to the drain EX at this time, the engagement force of the direct coupling clutch Cd itself decreases. Therefore, by interlocking with the timing valve 210 and blocking the drain oil passage 321 of the modulator valve 220 from the drain EX to prevent pressure oil from escaping anywhere, the engagement force of the direct coupling clutch Cd can be reduced during gear shifting. Deterioration can be prevented.

The pressure in the output oil passage 353 of the modulator valve 220 is
The oil is led to the cylinder 13 of the direct coupling clutch Cd in the torque converter T via the oil passage 326 from the bow) 230a of the on-off valve 230 via the oil passage 326 via the oil passage 326. Therefore, the engagement force (transmission capacity) of the direct coupling clutch Cd is strengthened according to the vehicle speed U and the opening degree of the throttle valve when the third electromagnetic valve 240 is closed. The on-off valve 230 receives the throttle pressure Pt through the oil passage 311 in the chamber 230A, and at the throttle pressure Pt, the spool 231 moves to the left in the figure against the spring force of the spring 232 to open the input oil passage 353. It is connected to the output oil passage 326, and when there is no throttle pressure Pt, that is, when the throttle valve opening is at the idle position, the spool 231 moves to the right by the spring force of the spring 232 and is held in the position shown in the figure, draining the oil passage 326. It connects to EX and also serves to connect oil passage 325 and oil passage 501. This on-off valve 230 is connected to the direct clutch Cd when the valve opening of the throttle valve is at the idle position.
This is to release the engagement. At this idle position, the oil passage 325 and the oil passage 501 are connected, so that the amount of oil flowing into the torque converter T from the inlet port Ta of the torque converter T increases, and the pressure inside the torque converter T increases. Since the piston 13 is pushed to the left in the figure, it is in the idle position (when the accelerator pedal is released)
Disengagement of the direct coupling clutch CdO can be reliably performed.

The third solenoid valve 240 controls the engagement force of the clutch Cd by controlling the opening and closing between the oil passage 326 and the drain EX to control the operating pressure of the direct coupling clutch Cd or the pressure of the piston 13. However, when the solenoid 242 of the third electromagnetic valve 240 is energized and opened, the throttle 373
As a result, the oil pressure in the oil passage 326 decreases, and the direct coupling clutch CdO
The engagement force (transmission capacity) is weakened.

The solenoid 242 of this third electromagnetic valve 24.0 is controlled by the electronic control unit 33 which measures the relative actual speed ratio e between the output member and the output member of the torque converter T. Controlled to stay within the range value.

When the solenoid 242 of the third solenoid valve 240 is deenergized and the solenoid valve 240 is closed, the modulator valve 240 is closed.
The output of 20 itself becomes the engagement force of the direct coupling clutch Cd, and this output acts on the hydraulic cylinder 13 via the on-off valve 230 and the oil passage 326, and the working pressure is as shown by the solid line ■ in FIG. , increases in proportion to vehicle speed U. In FIG. 4, the influence of the throttle pressure pt is omitted for the sake of simplicity.
This is what happens when 22 is omitted.

On the other hand, when the solenoid 242 of the third solenoid valve 240 is energized and the solenoid valve 240 is open, the hydraulic cylinder 13 is Since it is opened to the drain EX and the pressure decreases, the engagement force of the direct coupling clutch Cd becomes weak or zero, and its operating pressure has the characteristics shown by the broken line (■) in FIG.

Therefore, by controlling the duty ratio of the opening time of the third solenoid valve 240, the operating pressure of the direct coupling clutch Cd can be adjusted to the fourth solenoid valve 240.
It can be created arbitrarily between the solid line ■ and the broken line ■ in the figure.

In this embodiment, between the solid line I and the broken line ■ in FIG.
The duty ratio is controlled in 21 stages from θ to 20%, of which the representative one shown in Figure 4 is on-duty ratio (hereinafter simply referred to as duty ratio) of 60%.
The working pressure when the duty ratio is 30% is shown by the solid line (■), and the solid line (■) is the working pressure when the duty ratio is 30%. In Figure 4, the chain line ■
The straight line shown by indicates the internal pressure PT of the torque converter T, and the pressure difference between the operating pressure shown by the solid lines 1 to 2 or the broken line 2 and the internal pressure PT defines the strength of the engagement force of the direct coupling clutch CdO.

(Operation) FIGS. 5 to 7 are flow charts showing the method of the present invention,
The operation of the method of the present invention will be explained below along with this flowchart.

In FIG. 5, when the ignition switch is first turned on, the CPU of the electronic control unit 33 is initialized (
Step 1): All variables related to transmission capacity control of the direct coupling clutch Cd are set to initial values. Next step 2
Proceed to the vehicle speed detector 31, engine rotation speed detector 34.
, reads each input data from the gear position detector 35, etc., and measures the time intervals of the vehicle speed pulse signal and engine rotation speed pulse signal respectively input in step 3, and determines the vehicle speed U.
, the engine speed Ne is calculated, and the torque converter T, which will be described later, is calculated based on these vehicle speeds U and engine speed Ne.
The speed ratio e between the pump wheel 2 and the turbine wheel 4 (see FIGS. 1 and 2) is calculated (step 4).

This value e is calculated as follows.

When the turbine wheel rotation speed is N2, the speed ratio e of the torque converter T is expressed by the following equation.

- Since it is connected to the cable pulley 30 via a gear train, there is no slippage between them.If the reduction ratio between them is A and the rotation speed of the speedometer cable 30 is N3, then Rotation speed N2 of torque converter output shaft 3
is N2=A-N3 (2). When formula (1) is rearranged using formula (2), the speed ratio e is expressed by the following formula.

In this case, the value of the reduction ratio A may take values A1 to A4 corresponding to each of the detected speeds, that is, the reduction ratios of the first to fourth speeds.

Note that a rotation speed detector may be attached to the input shaft 3 of the auxiliary transmission M in order to determine the output side rotation speed of the torque converter T.

After calculating the speed ratio value e in step 4, the process proceeds to step 5, whereupon a routine for controlling the direct coupling clutch Cd (Cd, C0NTR0L) shown in FIG. 6 is executed.

In FIG. 6, first, in step 1, the engine speed Ne
is larger than a predetermined rotation speed Ne3 (for example, 3.50 rpm), and if the answer is affirmative (Yes), proceed to step 16 and turn off the third solenoid valve 240, that is, close it and directly connect it. The hydraulic pressure of the clutch Cd is increased to strengthen the engagement force of the direct coupling clutch CdO.

This is because if the engine speed Ne is 3.50 Orpm or higher, there is no risk of problems such as vibration occurring, and the direct coupling clutch Cd
By increasing the engagement force of the clutch, slippage of the clutch can be suppressed, and the life and fuel efficiency of the direct coupling clutch Cd can be improved.

At this time, the working oil pressure supplied to the direct coupling clutch Cd is maintained on the solid line ■ in FIG. 4.

If the answer to step 1 is negative (No), it is determined in step 2 whether or not the gear position of the auxiliary transmission M is the fourth speed, and if the answer is affirmative (Yes), step 6 is performed. If the answer is NO, the process proceeds to step 3, where it is determined whether the gear position is the third gear.

If the answer to Step 3 is affirmative (Yes), then if the gear position is the third gear, then to Step 5, negative (No).
In each case, proceed to step 4.

As a result of the determination in steps 2 and 3, when the vehicle is in fourth gear, the upper limit vehicle speed U32 is changed to the predetermined vehicle speed U432 in step 6.
(for example, 85 km/h), when the vehicle is in third gear, the upper limit vehicle speed U32 is set to the designated vehicle speed U332 (for example, 40 km/h) in step 5, and when the vehicle is in second gear or lower, the upper limit vehicle speed U32 is set to the designated vehicle speed U232 (for example, 30 km/h) in step 4.
km/h). In this way, the upper limit vehicle speed U32 is set to U232. U332. After setting the vehicle speed to either U or 02, proceed to step 7 and set the vehicle speed to U or 02.
is larger than the upper limit vehicle speed U32 set in any of steps 4 to 6, and if the answer is affirmative (Yes), problems such as vibration will not occur, so proceed to step 16. The third solenoid valve 240 is closed, and the engagement force of the direct coupling clutch Cd is strengthened.

If the answer to step 7 is negative (NO), that is, if the vehicle speed U is smaller than the upper limit vehicle speed U32, the process proceeds to step 8 where the vehicle speed U is changed to the lower limit vehicle speed U31 (for example, 6+++/
h) Determine whether the value is greater than or not. The answer is negative (No
), that is, the vehicle speed U is smaller than the lower limit vehicle speed U31,
In the case of a low vehicle speed range that requires the torque amplification function of the torque converter T, proceed to step 1 and install the third solenoid valve 24.
0, that is, by opening the valve, the direct coupling clutch C
d is lowered to weaken the engagement force of the direct coupling clutch Cd to utilize the function of the torque converter T. The working oil pressure supplied to the direct coupling clutch Cd at this time is indicated by the broken line ■ in Fig. 4.
change upwards. If the answer to step 8 is affirmative (Yes), that is, if the vehicle speed U is greater than the lower limit vehicle speed U3+, the process proceeds to step 9, where it is determined whether the gear position of the auxiliary transmission M is the fourth gear. do. If the answer to this step 9 is affirmative (Yes), in step 10 the vehicle speed U
is larger than a predetermined vehicle speed U36 (for example, 58 km/h), and if the answer is affirmative (Yes), that is,
When the gear position is the fourth speed and the vehicle speed U is higher than the predetermined vehicle speed U3G, in step 12, the determination values e1 (for example, 92%), 62 (for example, 97%), e+ (for example, 99. 5%), ea (
For example, 102%). The discrimination value e1 is an upper limit value of a region where the engagement force of the direct coupling clutch Cd is weak (hereinafter referred to as a weak engagement force region), and a lower limit value of a region that approximates the reference value (hereinafter referred to as a weak engagement force region). The discrimination value e2 is the upper limit value of the reference value approximation region and the lower limit value of the reference value region (target region). The discrimination value e3 is the upper limit value of the reference value region and the lower limit value of the fine adjustment region. The discrimination value e4 is the upper limit value of the fine adjustment region and the lower limit value of the region where the solenoid is turned on and the third electromagnetic valve 240 is opened (hereinafter referred to as the solenoid on region). Step 1
If the answer to 0 is negative (NO), that is, the relevant gear is in the 4th gear position.
If the vehicle speed U is smaller than the predetermined vehicle speed U%, the determination values e1 (e.g. 88%) and C2 are determined in step 13.
(e.g. 94%), C3 (e.g. 97.5%), e<(
For example, 99%).

If the answer to step 9 is negative (NO), that is, if the gear position is not the fourth gear, the process proceeds to step 11, where it is determined whether the gear position is the third gear. If the answer to step 11 is affirmative (Yes), that is, if the third speed
%), C2 (e.g. 94%), C3 (e.g. 97.5%)
) and C4 (for example, 99%).

If the answer to step 11 is negative (NO), that is, if the gear position is neither 4th speed nor 3rd speed, the process moves to step 15 and the discrimination values e1 (for example, 88%), C
2 (e.g. 94%), C3 (e.g. 97.5%), e<
(for example, 99%).

After setting the respective discrimination values 81 to e4 in steps 12 to 15, the process proceeds to step 17, where the duty ratio control of the solenoid valve 240 (solenoid valve DUTY C) shown in FIG.
0NTR0L) routine.

Steps 1, 2, 3 in FIG. In steps 7 and 7, it is determined in which region of the speed ratio range the current speed ratio e falls. First, considering that the speed ratio e changes from the bottom to the top, if the speed ratio e is in the weak engagement force region, it is difficult to determine whether the speed ratio e is larger than the discrimination value e1 in step 7. The answer is negative (No), and in step 8 it is determined whether the timer period T1 has elapsed (T=O).

FIG. 8 shows the duty ratio control state when the speed ratio e passes from the weak engagement force region to the upper reference value approximation region and enters the upper reference value region. As the speed ratio e approaches the reference value region, the rate of increase in the transmission capacity of the direct coupling clutch Cd is controlled to be reduced, that is, the rate of change in the transmission capacity is controlled to be small.

When the speed ratio e is in the weak engagement force region, T1 (for example, 0
．． Every time a period of
By controlling the duty ratio of the zero valve opening time, the engagement force of the direct coupling clutch Cd is gradually strengthened. In FIG. 7, if the answer to step 8 is affirmative (Yes), that is, when the timer period (T1) has elapsed (tl in FIG.
.

t2. and time t3) Each time, in step 9, the timer is set to the value T1, and in step 10, the variable value is set to a value (D-xl) smaller than the previous value by xl, and this is stored. The duty ratio control of the opening time of the third electromagnetic valve 240 (steps 8 to 13) is repeated again over the T1 period at the duty ratio at the stage indicated by the value. Note that step 11 is a limit check, and if the variable value becomes less than 0, problems will occur in program control. Therefore, it is determined whether the variable value is greater than the minimum D11im (for example, O), and the answer is In case of denial (No),
That is, when the variable value is smaller than O, the value of the variable is set to the minimum value D11im in step 12, and step 13
Move to. If the answer to step 11 is affirmative (Yes), that is, if the variable value is greater than 0, step 12
Skip this and move on to step 13.

In step 13, the value of the variable set in step 10 is stored as a variable D32 for later use in control when the speed ratio e enters the reference value range. After this, in step 14, the solenoid 2 of the third solenoid valve 240 is
A counter for controlling the energization time to 42 is set to a value corresponding to the variable value, and then the process returns to step 2 in FIG. 5 and is executed again. Note that the electronic control device 33 operates the third solenoid valve 24 at the same duty ratio, that is, at a constant cycle, until the duty ratio of the third solenoid valve 240 is set to a new value.
Repeat 0 valve opening. Here, the duty ratio of the third solenoid valve 240 is the ratio of the energization time to the solenoid 242 to a predetermined time (for example, 100 m5), and +Do
- When set to 21 steps of D20, the energization time per step is 5 ms.

In this way, when the speed ratio e is in the weak engagement force region, the engagement force of the direct coupling clutch CdO is gradually strengthened toward x1 every period T1.

Next, when the speed ratio e enters the reference value approximation region (at time t4 in FIG. 8), the answer to step 7 becomes affirmative (Yes),
In step 15, it is determined whether the timer period has elapsed.

The timer period here is when the speed ratio e is in the weak engagement force region immediately before entering the reference value approximation region, that is, t3 in FIG.
This is the value T1 set at the time. If the answer to step 15 is negative (NO), that is, unless the timer period T1 has elapsed, steps 16 to 19 are not executed and step 13 is performed.
and 14 are executed, and the third solenoid valve 240 is subsequently controlled to open at the duty ratio set in the weak engagement force region.

If the answer to step 15 is affirmative (Yes), that is,
When the timer period T1 has elapsed (at time t5 in Figure 8)
In step 16, the timer is set to the T in the weak engagement force region.
Set a predetermined value T2 (for example, 1 second) larger than 1 value, and in step 17 set the variable value to X2 (
For example, set a value (D -
Duty ratio control of the opening time of the third solenoid valve 240 is performed over two periods. Then, when the timer period T2 has elapsed again and the speed ratio e value is still in the reference value approximation region (
t6 in FIG. 8), steps 15 to 1 in the same way as above.
Repeat steps 9 and 13. Note that step 18
is a limit check similar to step 11, which determines whether the variable value is greater than the minimum value D21im (for example, O), and if the answer is negative (NO), that is, the variable value is less than 0. If so, the value of the variable is set to the minimum D21im in step 19, and the process moves to step 13.

If the answer to step 18 is affirmative (Yes), that is,
If the variable value is greater than 0, the process moves to step 13 without executing step 19.

When the speed ratio e enters the reference value region at time t7 in FIG. 8, the answer to the determination as to whether the speed ratio e is greater than the discrimination value e2 in step 3 becomes affirmative (Yes), which will be described later in step 20. The flag F1 is set to 0 and the process proceeds to step 21, where it is determined whether or not a flag F3, which will also be described later, is set to 1.

When the speed ratio e enters the reference value region from a smaller value, flags F2 and F3 are both set to 0 (
Steps 5 and 6), the answer to step 21 is negative (N
o), and the answer to the determination in the next step 24 as to whether or not flag F2 is set to 1 is also negative (No), in which case the process moves to step 26 and it is determined whether or not the timer period has elapsed. The timer period here is the value T2 set when the speed ratio e is in the reference value near-image region, that is, at time t6 in FIG. The answer to step 26 is negative (N
o), that is, step 27 until the timer period T2 has elapsed.
Steps 41 to 4 described below without performing steps 41 and 28
Step 6 is followed by step 14, and the third solenoid valve 240 is subsequently controlled to open at the duty ratio set in the reference value approximation region.

If the answer to step 25 is affirmative (Yes), that is,
When the timer period T2 has elapsed (time point 18 in FIG. 8),
In step 27, a unique value when the speed ratio e is in the reference value region, that is, the value T3 (for example, 2 seconds) is set in the timer again, and in step 28, it is stored as the variable value D32 in step 13 in the previous loop. The value set when the speed ratio e is in the reference value approximation region immediately before entering the reference value region (time t6 in FIG. 8) is set as is. In this way, if the speed ratio e falls within the reference value region,
Without rewriting the value of the variable, the value set immediately before entering the reference value area (time t6 in Figure 8) is used to control the third electromagnetic pulse until the timer period T3 has elapsed (time t9 in Figure 8). The valve opening time of the valve 240 is duty-controlled. Even after time t9, as long as the speed ratio e is within the reference value range, the transmission capacity of the direct coupling clutch Cd is controlled not to be changed.

FIG. 9 shows a duty ratio control state using a method different from that in FIG. 8 in duty ratio control when the speed ratio e enters the reference value region from the weak engagement force region through the reference value approximation region as in FIG. 8. . That is, in the case of FIG. 8, xl and x2
In addition to setting the value of T1. By making the values of T2 and T3 different, the rate of change over time of the speed ratio e becomes smaller as the speed ratio e approaches the reference value region, whereas in the case of FIG. By setting the values of T2 and T3 to be the same and making the values of xl and x2 different, the speed ratio e becomes smaller as the speed ratio e approaches the reference value region.
This is a reduction in the rate of change over time.

Figure 10 shows the duty ratio control state when the speed ratio e exceeds the reference value region, enters the fine adjustment region above the reference value region, and returns to the reference value region again without exceeding the fine adjustment region. shows. In this case, if the speed ratio e enters the reference value range from below, the values of all flags Fl, F2, and F3 are O. Therefore, the speed ratio e increases from the time t1o in FIG. 10(a) to 1
When the speed ratio e exceeds the reference value region and enters the fine adjustment region directly above it at point ++, the speed ratio e becomes the discrimination value e in step 2 of FIG.
The answer to the determination as to whether it is greater than 3 is affirmative (Yes), and the process moves to step 29, where the flag F1 is set to 1, and then the process moves to step 30. In step 30, it is determined whether or not the flag F2 is O.
Since is still set to 0, the answer to the determination is affirmative (Yes), and the process moves to step 31, where flag F2 is set to 1.

Next, in step 32, the variable D32 is set as the variable value D33.
Store the value of . This D32 value is the D value used when the speed ratio e is within the reference value region, that is, the D value used in step 28.
This is the same as the D value set in . Incidentally, FIG. 10 shows changes over time in the values of variables D32 and D33 together with changes in the speed ratio e. In this case, each value of the variables etc. shows only the increase/decrease value with respect to the value set when the speed ratio e value is in the reference value region. Then step 3
Step 3 sets the timer to a predetermined value T4 (for example, 0.4 seconds), and step 34 sets the variable value to be used for control this time.
After setting a value obtained by adding X6 (for example, 6) to D33 used in the previous control, the process returns to step 2 in FIG. 5 via steps 41 to 46 and 14, which will be described later, and is re-executed.

What should be noted here is that when the speed ratio e is in the reference value region just before entering the fine adjustment region, that is, (a
), the timer period T3 set at time t10 is t'1
There is no time-up until time 1, but t11 when the speed ratio e reaches the discrimination value e3, that is, the lower limit value of the fine adjustment area.
At this point, the timer is immediately reset to the value T4 (step 33), and control is repeated using the value of D set in step 34 until the T4 period has elapsed. When step 30 is reached through such repetition, flag F2 is likely to be set to 1 in step 31 in the previous loop, so the answer to step 30 becomes negative (No) and the process moves to step 35, where the timer period T,ll is still in effect. Since the time has not expired, the answer to the determination as to whether or not the timer period has elapsed in step 35 is negative (No), and the variable value D3 is changed in step 36.
2 to the D33 value set in step 32 above.
(For example, 1) is added and the value is stored. Since the value D32 was set as the variable value D33 in step 32 in the previous loop, if the value set when the speed ratio e is in the reference value region is Do, then the value newly stored as the D32 value is this value.

It is equal to the value obtained by adding x3 to

Before the speed ratio e passes the timer period T4, that is,
If it returns to the reference value area again at time t+2, the answer in step 3 becomes affirmative (Yes), and the process moves to step 20, where the flag F1 is set to O. In the next step 21, in this case, the flag F3 is set to 0. Since it is still set to , the process skips over this and moves to step 24. Since flag F2 was set to 1 in step 31, the answer to step 24 is affirmative (Yes), and the process moves to step 25 to set flag F2.
is set to 0, skipping step 26 and proceeding to step 27, where the predetermined value T3 is set in the timer. That is, skipping step 26 and proceeding to step 27 means that the timer is reset as soon as the speed ratio e returns to the reference value range.

Next, in step 28, the value D32 stored in step 36 in the previous loop is set as a variable value, and the duty ratio of the opening time of the third solenoid valve 240 is controlled at the duty ratio of the stage indicated by the value of D32.

Then, even at time ti3, when the speed ratio e has elapsed during the timer period T3, as long as it is within the reference value range, the T3 value is set in the timer again (step 27), and the D value remains the same from time t14 onwards. Value D32 (Step 2
(day) to control the duty ratio.

In the case of (a) in FIG. 10, the speed ratio e exceeds the reference value region and enters the fine adjustment region for a short period of time (a period shorter than the timer period T, !I). In other words, as the speed ratio e entered the fine adjustment region, it was corrected with a large value x6 at time t11, and as a result, it immediately returned to the reference value region at time ti2, when the timer period T and lI had not elapsed. The x6 value was too large. Therefore, at the time t12 when the value returned to the reference value area, a small correction value x3 was added to the variable value set in the reference value area immediately before exceeding the reference value area, that is, at the time 100. By controlling the duty ratio using the value, the speed ratio e is maintained within the reference value range.

In the case of (bl in FIG. 10), the speed ratio e increased from the time ti5 and exceeded the reference value region and entered the fine adjustment region, so correction was applied at the time the time with a large value of x6, It does not immediately return to the reference value area but stays in the fine adjustment area for a long time (
This is a case where the timer stays for a time longer than the timer period T4. In this case, immediately before exceeding the reference value area and entering the fine adjustment area, the time period during which the speed ratio e value remains in the fine adjustment area is determined by adding the x6 value to the D value set at time t15. The speed ratio e is maintained in the reference value region by controlling the duty ratio using a value added according to the speed ratio.

Therefore, in the case of (b) in FIG. 10, steps 29 to 34 are executed at time t+6, similarly to the case at time t11 in (a) of FIG. 10, and from time t16 to ti7
Until that point is reached, steps 29, 30, 35 and 36 are executed respectively. Then, when the timer period T4 times up for the first time when the time N7 is reached, the answer in step 35 becomes affirmative (Yes), and the process moves to step 37, where the flag F3 is set to 1, and then, in step 38, the variable The value used in the previous loop is stored in D33 as the value. Then, in step 39, the timer is set to the T4 value again, and in step 40, a value obtained by adding the value Xl (for example, 1) to the D value is set. Then, steps 29, 30, 35 and 36 are executed again until the timer period T4 times up at day t1, and in step 36, a value obtained by adding the value x3 to the D33 value is stored as the D32 value. If the speed ratio e is still in the fine adjustment region at time t+8, the stainless steel 7" 37.38
Execute each. Execution of steps 37 and 38 means that the D33 value is updated to the value obtained by adding the value x3, and the duty value increases again by adding the value x3 to the D value in step 40. , duty ratio control is repeated with this value. Then, when the speed ratio e returns to the reference value region at time t19, steps 20 and 21 are executed. The answer to step 21 is affirmative (Yes) because flag F3 is set to 1 in step 37, and flag F3 is set to 0 in step 22, and step 23
Then, the flag F2 is set to 0, and step 24 is skipped and the process proceeds to step 26, where it is determined whether or not the timer period T4 has timed out. Skipping step 24, ie, not determining flag F2, means that the speed ratio e is changing slowly. If the speed ratio e is changing slowly, the duty value set in the previous loop is used as is. That is, it waits until the timer period T4 elapses, that is, until time t119, and then performs duty control using the duty value set in the previous loop as is. Then, when the time point t°19 is reached, the answer in step 26 becomes affirmative (Yes), the timer is set to the T3 value in step 27, and the T3 value is set in the timer in step 28.
Set the value D32 to the variable value. This D32 value is the value set immediately before the fine adjustment area set in step 36 is extracted.

In this way, when the speed ratio e returns to the reference value region, duty ratio control is continued based on the variable value, and as long as the speed ratio e remains within the reference value region, the value is maintained after time t20 and the duty ratio is maintained. Control the ratio.

FIG. 11 shows the control state when the speed ratio e goes from the reference value region to the fine adjustment region, enters the solenoid ON region, and then returns to the reference value region again.

(In addition, FIG. 11 shows a state in which the speed ratio e is in a range larger than the discrimination value e4, that is, in the solenoid ON region.

FIG. 11(a) shows the case where the speed ratio e passes through the fine adjustment region in a short time and enters the region where the solenoid is turned on.
FIG. 11(b) shows the case where the speed ratio e takes a long time to pass through the fine adjustment region and enters the region where the solenoid is turned on. In both cases (a) and (b) of Fig. 11, the speed ratio e approaches the upper limit value 1.0 (an) (therefore, there is a risk of car body vibration, so the duty ratio is set to the highest value D20).
(The solenoid 242 of the third solenoid valve 240 is turned on to open the solenoid valve 240.) However, when the speed ratio e returns from the solenoid on region to the fine adjustment region, the duty value is In FIG. 11, (a) is set to a larger value than (b).

That is, in (a) of FIG. 11, when the speed ratio e increases from time t29 and enters the fine adjustment region at time t30, the answer to step 2 of FIG. 7 becomes affirmative (Yes) and the first
Steps 29 to 34 are respectively executed in the same manner as explained in FIG. At this time, the D value and D33 value are +XS (for example, 4) and +0, respectively, with respect to the previous value.

And in the next loop steps 29.30.35 and 36
are respectively executed, and in step 36 the D33 value is set to the value)l
The value obtained by adding (for example, 1) is stored as the D32 value. At this time, flag F3 remains at 0. In this state, if the speed ratio e exceeds the fine adjustment region before the timer period T4 elapses (at time t31), the answer to the determination as to whether the speed ratio e in step 1 in FIG. 7 is greater than the discriminant value e1 is The result is affirmative (Yes), and the process moves to step 47 where flag F is set.
2 is set to 1, and in step 48 it is determined whether the flag F3 is set to 1. As mentioned above, flag F
3 remains O and the speed ratio e has left the fine adjustment region and entered the solenoid on region, so the answer to step 48 is negative (No.
), the process moves to step 50 and the value X5 is added to the D33 value.
(For example, 6) is added and the value is stored as the D value. Next, in step 51, it is determined (limit check) whether the D value is larger than the DFO value (=20). If the answer is affirmative (Yes), the D value is set to the value DFO in step 52 and the process moves to step 53. If the answer is negative (No), step 52 is skipped and the process moves to step 53. In step 53, the D value (for example, +6) set in step 51 is stored as the D32 value, in step 54 the timer is set to 0, and in step 55, the solenoid 2 of the third solenoid valve 240 is
42 is turned on to maintain the solenoid valve 240 in the open state, while at step 56 the electronic control unit 33 stops the valve opening duty ratio control of the third solenoid valve 240, and the fifth solenoid valve 240 is turned on again.
Return to step 2 in the diagram.

Then, when the speed ratio e enters the fine adjustment region again at time t32 in (a) of FIG. 11, the answer to step 2 of FIG. 7 becomes affirmative (Yes), and the flag F1 is set to 1 in step 29. The answer to step 30 is negative because flag F2 was set to 1 in step 47 of the previous loop.
Proceed to step 35.

The answer to step 35 is affirmative (Yes) because the timer was set to 0 in step 54 of the previous loop.
In step 37, the flag F3 is set to 1, and in the next step 38, the D value (+x5, ie, +6) is stored as the D33 value. Then, in step 39, the timer is set to the predetermined value T.
4, and in step 40 the value of D+x3 (i.e. +6+
1=+7) as a new value, and in step 36 of the next loop, the value of D33+X3 (i.e. +6+1=+7)
is stored as a D32 value.

Thereafter, at time t33, the speed ratio e continues to enter the fine adjustment region, so steps 29, 30°35.3
Execute steps 7 to 40, respectively. D value (+7) in step 38
is stored as a D33 value, and in step 40, the value of D+x3 (+8) is stored as a D value. Then, the answer to step 35 becomes negative (NO) again, and the process moves to step 36.
The value of D33+x3 (+8) is stored as the D32 value.

Next, when the speed ratio e enters the reference value region at the time t133, it is controlled by the same effect as the time t19 to t°19 in FIG. e
As long as D is within the reference value range, the duty ratio is controlled without changing the D value.

In the case of (b) in Figure 11, when the speed ratio e enters the fine adjustment region at time t35, steps 29 to 34 in Figure 7 are executed, respectively, in the same way as at time t30 in Figure 11 (a). Then, in step 32, it becomes D32, that is, +0, and in step 34, it becomes D33.
The value of +x6 (+4) is stored as the D value, and in step 36 of the next loop, D33+X3 (+1) is stored as the D32 value. Since the speed ratio e is still in the fine adjustment region at the time tI after the T4 period has elapsed, steps 29 and 30 are performed.
．． 35 and 37 respectively, and in the next step 38 the D value (+4) is stored as the D33 value, and in step 39.40
are executed respectively, and in step 40 the value of D+x3 (+5
) is stored as a D value.

Then, at time t37, when the speed ratio e leaves the @adjustment region and enters the solenoid ON region, the answer to step 1 in FIG. 7 becomes affirmative (Yes), and steps 47 and 48 are executed, respectively. In this case, the speed ratio e changes from the time t35 to the first T
Since the fine adjustment region has been entered until the time t37 in the middle of the next T4 period after four periods have elapsed, the speed ratio e changes gradually, and 1 is set in the flag F3. Therefore, the answer to step 48 is affirmative (Yes), and the process moves to step 49 to obtain the value of D33+X4, that is,
+5 is set as the D value, and then step 52 is executed. If the answer is affirmative (yes), the process moves to step 53; if the answer is negative (no), step 52 is skipped and the process moves to step 53. In step 53, the D value set in step 49, that is, +5, is stored as the D32 value, and thereafter steps 53 to 56 are executed, respectively, and the process returns to step 2 in FIG. 5 to be executed again.

Then, at time t38, when the speed ratio e enters the fine adjustment region again, steps 29, 30, 35 and 37 are executed, respectively.
In the next step 38, set the D value (D33+x<=+5)
It is stored as 33 values. Next, in step 40, the value D33+)l=+6 is stored as the D32 value.

Thereafter, when the speed ratio e enters the reference value region at time t3B, when the T4 period has not elapsed, from t12 to (a) in FIG.
It is controlled by the same effect as at time ti3.

After passing through time t41, the duty ratio is controlled without changing the value of D as long as the speed ratio e is within the reference value range.

Note that F1=1 in step 4 in FIG. 7 means that the speed ratio e once enters the fine adjustment region from the reference value region, and the speed ratio e in the next loop passes through the reference value region and changes to the lower coefficient. When entering the weak resultant force region, that is, when the speed ratio e changes rapidly, the flag Fl is set to 1, which means that control should be performed using the D value set in the previous fine adjustment region.

In addition, steps 41 to 46 are limit checks and D
If each value of 32 and D33 is larger than the DFO value (for example, 20), each of these values is rewritten to the value DFO.

In addition, although the above embodiment describes the case where a fluid torque converter T is employed as the fluid power transmission device, the present invention can be applied to any automatic transmission for a vehicle equipped with other types of fluid couplings, etc. -0 Furthermore, the predetermined parameter representing the relative slippage amount between the human body and the output member of the hydraulic power transmission device may be the difference between the respective rotational speeds of the human body and the output member.

(Effects of the Invention) As detailed above, according to the direct coupling mechanism control method for a fluid power transmission device of an automatic transmission for a vehicle of the present invention, a predetermined amount of slippage between the input and output members of the fluid power transmission device is determined. The measured value of the parameter value is compared with a predetermined reference range value set in advance, and based on the comparison result, the transmission capacity of the direct coupling mechanism for a predetermined period to be implemented from now on is determined, and the parameter value is determined to be within the predetermined reference range. A reduction area in which the transfer capacity is zero or significantly reduced when the parameter value is greater than or equal to the value is set above the predetermined reference range value, and when the parameter value goes below the reduction area, the transfer capacity is such that the parameter value is The transmission capacity is set to be smaller than the transmission capacity when entering the reduction region from the predetermined reference range value.

Therefore, even if the transmission capacity of the direct coupling mechanism is set to a strong bow, the transmission capacity can be stably and quickly controlled to the reference value (target value) range without causing divergence, and the generation of vehicle body vibration and noise is suppressed. At the same time, the fuel efficiency and power transmission characteristics are improved, and an extremely smooth and comfortable driving feeling can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an automatic transmission for a vehicle to which the direct coupling mechanism control method of the present invention is applied, Fig. 2 is a hydraulic control circuit diagram of the automatic transmission for the same vehicle, and Fig. 3 is a diagram of the direct coupling clutch of Fig. 2. Exploded view of main parts, Figure 4 is a graph showing the relationship between the working oil pressure of the direct coupling clutch 7 and vehicle speed, Figure 5 is the main flowchart showing the control procedure for the working oil pressure (transmission capacity) of the direct coupling clutch, and Fig. 6 is a sub-flowchart showing the control procedure carried out in step 5 of Fig. 5, Fig. 7 is a sub-flowchart showing the control procedure carried out in step 17 of Fig. 6, and Fig. 8 is a sub-flowchart showing the control procedure carried out in step 17 of Fig. 6. A graph showing the relationship between the speed ratio and the duty ratio in control when the timer period is varied and the speed ratio moves from the weak engagement force region through the reference value approximation region and enters the reference value region. 10th graph showing the relationship between speed ratio and duty ratio in control when the positive values are different, the timer period is the same, and the speed ratio passes from the weak engagement force region through the reference value approximation region and enters the reference value region. The figure shows the relationship between speed ratio and duty ratio in control when the speed ratio exceeds the reference value region, enters the fine adjustment region above the reference value region, and returns to the reference value region again without exceeding the fine adjustment region. Figure 11 shows the relationship between the speed ratio and duty ratio in control when the speed ratio goes from the reference value region to the fine adjustment region and enters the region where the solenoid is turned on, and then returns to the reference value region. This is a graph showing. T...Torque converter (hydraulic power transmission device), 2
... Pump impeller (input member), 4... Turbine impeller (output member), Cd... Direct connection clutch (direct connection mechanism). Applicant Honda Motor Co., Ltd. Agent Patent Attorney Toshi Watanabe Otoma Kanji Nagato, A3 figure, 5 figures

Claims (1)

[Claims] 1. The predetermined parameter value representing the relative slip amount of the input and output members of a hydraulic power transmission device having an input member and an output member is within a predetermined reference range set in advance. In the method for controlling a direct coupling mechanism of a hydraulic power transmission device for a vehicle automatic transmission, which variably controls the transmission capacity of a direct coupling mechanism that mechanically engages the input and output members, the actual measurement of the predetermined parameter value Compare the value with the predetermined reference range value,
Based on the comparison result, the transfer capacity for the predetermined period to be implemented from now on is determined, and when the parameter value is greater than or equal to the predetermined reference range value, a reduction area in which the transfer capacity is zeroed or significantly reduced is set in the predetermined reference range. The transmission capacity is set to an upper side of the value, and the transmission capacity when the parameter value goes below the reduction area is set to be smaller than the transmission capacity when the parameter value enters the reduction area from the predetermined reference range value. Claim 1 characterized in that
A method for controlling a direct coupling mechanism of a fluid power transmission device for an automatic transmission for a vehicle as described in 2. 2. Direct coupling mechanism control of a hydraulic power transmission device of an automatic transmission for a vehicle according to claim 1, wherein the predetermined parameter is a ratio of the respective rotational speeds of the input member and the output member. Method. 3. Direct coupling mechanism control of a hydraulic power transmission device for an automatic transmission for a vehicle as set forth in claim 1, wherein the predetermined parameter is a difference between the respective rotational speeds of the input member and the output member. Method. 4. A direct coupling mechanism control method for a fluid power transmission device for an automatic transmission for a vehicle according to claim 1, characterized in that the transmission capacity is kept constant within the predetermined period. 5. The automatic transmission for a vehicle according to claim 1, wherein the transmission capacity is determined in advance according to a state of change of the parameter value from the predetermined reference range value before entering the reduction region. Direct coupling mechanism control method for a fluid power transmission device.