JPH10299889A - Automatic transmission controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress shift shocks at the determination of a descent by reducing engaging shocks of engine-brake friction elements with no addition of other devices. SOLUTION: An automatic transmission controller involves a driving state detection means for detecting the driving state of a vehicle including at least the grade of a road on which the vehicle runs, and a shift control means 40 for controlling the engaging state of plural friction elements on the basis of the results detected by the detection means. When the vehicle running road has downhill grades not less than a predetermined value, the control means 40 controls the engaging state of the friction elements for downshifting, and during that downhill grade-based downshifting, the control means also brings the friction elements out of all the friction elements, which allow power transmission from driving wheels 3 and 4 to an engine 5 when shifted into their engaging state from released state by the downshifting, temporarily released after the lapse of a predetermined period from the start of their engagement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a downshift from a fourth speed to a third speed when a downhill judgment is made, supplying hydraulic pressure to a coasting latch (hereinafter abbreviated as a coast clutch) to automatically perform engine braking. The present invention relates to a control device for an automatic transmission, such as an automatic transmission.

[0002]

2. Description of the Related Art In a general automatic transmission control system, when a descent is determined, a fourth speed (coast clutch OFF) to a third speed (a state in which the engine is driven from the wheels by the coast clutch ON and the engine brake is applied). Control (slope control) for shifting downshifts, switching the coast latch from OFF to ON, and applying engine braking is performed.

[0003] However, since this slope control is not a manual operation by the driver's will, if the above-mentioned coast clutch is suddenly changed to the engaged state during the 4-3 downshift, the driver feels uncomfortable. there were. In order to solve such a problem, for example, a control device for an automatic transmission described in Japanese Patent Application Laid-Open No. 6-346957 has already been invented.

That is, a device for lowering the operating oil pressure in order to reduce the engagement force to the coast clutch when shifting to a gear position where the engine brake is automatically applied (for example, when shifting down from the fourth speed to the third speed). Is added to reduce the shift shock when the downshift is performed to the engine brake operating low gear by the automatic engine brake control, thereby reducing the uncomfortable feeling given to the driver. However, in the conventional apparatus, it is necessary to separately add a device, and there has been a problem that its configuration is complicated.

[0005]

According to the first aspect of the present invention, the downshift is performed when the downhill gradient is equal to or more than a predetermined value, and the downshift is changed from the disengaged state to the engaged state during the downshift. When a predetermined time elapses after the engagement of a friction element (coast clutch) that enables the transmission of power from the drive wheels to the engine by engagement, the friction element (coast clutch) is temporarily operated in the release direction to provide any device. It is an object of the present invention to provide an automatic transmission control device capable of reducing an engagement shock due to an engine brake friction element (coast clutch) without adding a gear, and suppressing a shift shock at the time of downhill determination.

According to a second aspect of the present invention, in addition to the object of the first aspect, the engagement is performed only when the operating pressure is supplied to the hydraulic chamber, and the drive is performed by the engagement. Providing a friction element (coast clutch) that enables transmission of power from the wheels to the engine, and temporarily discharging the operating pressure from the hydraulic chamber during a downshift based on a descent gradient of not less than a predetermined value. Thus, the engagement shock due to this friction element (coast clutch) can be reduced,
It is an object of the present invention to provide a control device for an automatic transmission that can suppress a shift shock at the time of downhill determination.

According to a third aspect of the present invention, in addition to the object of the second aspect, a shift signal (for example, 4
(-3) a downshift signal is output and the operating pressure is discharged from the hydraulic chamber until the turbine speed of the torque converter reaches a predetermined speed by the speed change. It is an object of the present invention to provide a control device for an automatic transmission in which the time for controlling the operation pressure to be discharged can be set to an appropriate time that does not cause a shift shock.

According to a fourth aspect of the present invention, in addition to the object of the second aspect of the present invention, the above-described hydraulic pressure during the 4-3 shift down shift based on the down slope being equal to or more than a predetermined value is provided. The present invention provides a control device for an automatic transmission capable of reducing the engagement shock due to the coast clutch by temporarily discharging the operating pressure from the chamber (fourth hydraulic chamber) and suppressing the shift shock at the time of downhill determination. Aim.

[0009]

According to a first aspect of the present invention, a power transmission path between an engine and driving wheels is provided by providing a plurality of friction elements and changing the engagement state of each friction element. Shifting means for switching, operating state detecting means for detecting an operating state of the vehicle including at least a gradient of a traveling path of the vehicle, and shifting for controlling an engagement state of the plurality of friction elements based on a detection result of the operating state detecting means. Control means for controlling an engagement state of the plurality of friction elements to perform a downshift when the downhill gradient of the vehicle traveling road is equal to or more than a predetermined value, and the downhill gradient is set to the predetermined value. During the shift-down shift based on the above, among the plurality of friction elements, the shift from the open state to the engaged state by the shift-down shift causes the drive wheels to move from the engine to the drive wheels. After starting the engaging friction elements that enable the force transmission, characterized in that Ki when a predetermined time has elapsed, a control apparatus for an automatic transmission to operate temporarily opening direction.

According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, a first hydraulic chamber and a second hydraulic chamber are provided as the plurality of friction elements. Is engaged only when the operating pressure is supplied only to the chamber, when the operating pressure is supplied to both the first and second hydraulic chambers, when the operating pressure is supplied only to the second hydraulic chamber, and 1st, 2nd
A first friction element that is released when both of the hydraulic chambers are not supplied with the operating pressure, and a second friction element that has a third hydraulic chamber and is engaged only when the operating pressure is supplied to the third hydraulic chamber. A third element that includes a friction element and a fourth hydraulic chamber, is engaged only when the operating pressure is supplied to the fourth hydraulic chamber, and enables the transmission of power from the driving wheels to the engine by the engagement. A first, second, and third shift control means.
Hydraulic oil supply / discharge means for adjusting supply / discharge of hydraulic oil to / from each of the third and fourth hydraulic chambers; and a shift characteristic preset according to an operation state and a detection result of the operation state detection means. Control means for controlling the hydraulic oil supply / discharge means, wherein the control means supplies operating pressure to the first hydraulic chamber and the fourth hydraulic chamber, and supplies hydraulic oil to the second hydraulic chamber and the third hydraulic chamber. When the first gear is not supplied and the descending slope of the traveling path of the vehicle is equal to or more than a predetermined value, the first, second, third, and fourth hydraulic chambers are operated from the first gear. In order to shift to a second shift speed lower than the first shift speed to which the oil is supplied, the hydraulic oil supply / discharge means is controlled, and during the shift based on the fact that the downward slope is equal to or higher than the predetermined value. And a control device for an automatic transmission for controlling hydraulic oil supply / discharge means so as to temporarily discharge operating pressure from a fourth hydraulic chamber. And it features.

According to a third aspect of the present invention, in addition to the configuration of the second aspect of the present invention, a torque converter is provided between the engine and the speed change means, and the control means is provided with a first control means. When the downshift of the traveling path of the vehicle is at or above the predetermined value at the shift speed, a shift signal for shifting to the second shift speed is output, and the hydraulic oil supply / discharge means is controlled based on the shift signal. The operating oil supply / discharge means is configured to discharge the operating pressure from the fourth hydraulic chamber until the turbine speed of the torque converter reaches a predetermined speed at which the speed change is not completed after the speed change signal is output until the speed is changed. Is a control device for an automatic transmission for controlling

According to a fourth aspect of the present invention, in addition to the configuration of the second aspect, the first speed is the fourth speed and the second speed is the third speed. Wherein the first friction element is a 2-4 brake which is disengaged at a third speed engaged at a fourth speed, and wherein the second friction element is engaged at a third speed,
It is a control device for an automatic transmission, wherein the control device is a 3-4 clutch that is engaged in a third speed, and the third friction element is a coast clutch that is engaged in a third speed.

[0013]

According to the first aspect of the present invention, the transmission means switches the power transmission path between the engine and the drive wheels by changing the engagement state of each friction element, The above-mentioned driving state detecting means detects at least the driving state of the vehicle including the gradient of the traveling path of the vehicle, and the above-mentioned shift control means controls the engagement state of the plurality of friction elements based on the detection result of the driving state detecting means. I do.

In addition, the above-mentioned shift control means controls the engagement state of the plurality of friction elements for downshifting when the downhill gradient of the vehicle traveling road is equal to or more than a predetermined value (the downhill is steep). When a predetermined time has elapsed after the start of engagement of a specific friction element (coast clutch) during downshifting based on the fact that is equal to or more than a predetermined value, the specific friction element (coast clutch) is temporarily operated in the release direction. As a result, there is an effect that the engagement shock due to the engine brake friction element (coast clutch) can be reduced without adding any other device, and the shift shock at the time of the downhill determination can be suppressed.

According to the invention described in claim 2 of the present invention,
In addition to the effect of the first aspect of the present invention, the fourth hydraulic chamber is engaged only when the operating pressure is supplied to the fourth hydraulic chamber, and by engaging the second hydraulic chamber, power can be transmitted from the drive wheels to the engine. Since a three-friction element (coast clutch) is provided and the operating pressure is temporarily discharged from the above-mentioned fourth hydraulic chamber during downshifting based on the descent gradient being equal to or more than a predetermined value,
There is an effect that the engagement shock due to the third friction element (coast clutch) can be reduced, and the shift shock at the time of downhill determination can be suppressed.

According to the third aspect of the present invention,
In addition to the effect of the second aspect of the present invention, the transmission signal (for example, a transmission signal for 4-3 downshifting) is output until the turbine speed of the torque converter reaches a predetermined speed by the speed change. Since the operating pressure is discharged from the fourth hydraulic chamber, there is an effect that the time for controlling to discharge the above-mentioned operating pressure can be set to an appropriate time such that no shift shock occurs.

According to the invention described in claim 4 of the present invention,
In addition to the effect of the second aspect of the present invention, the operating pressure is temporarily discharged from the fourth hydraulic chamber during the 4-3 downshift based on the fact that the downward slope is equal to or more than the predetermined value. There is an effect that the engagement shock due to the coast clutch can be reduced, and the shift shock at the time of downhill determination can be suppressed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawing shows the control device of the automatic transmission.
The overall configuration of the vehicle will be described with reference to FIG.

In FIG. 1, this vehicle has left and right front wheels 1 and 2 as driven wheels, left and right rear wheels 3 and 4 as driving wheels, and the output torque of an engine 5 is transmitted from an automatic transmission 6 to a propeller shaft 7. The power is transmitted to the left and right rear wheels 3 and 4 via the driving device 8 and the left and right drive shafts 9 and 10.

Each of the wheels 1 to 4 has these wheels 1
4 and a caliper 12 that receives the supply of a braking pressure (brake pressure) and brakes the rotation of the disks 11.
When the brake pedal 3 is depressed, the braking pressure is supplied to the above-mentioned calipers 12 to brake the rotation of each of the wheels 1-4, and a throttle valve 14 is disposed in the intake system of the engine 5 so that the accelerator pedal 15 is depressed. As a result, the throttle valve 14
Is changed, the intake air amount Q is variably controlled, and the engine output is adjusted.

Further, the above-mentioned vehicle has a vehicle speed sensor 16 for detecting the vehicle speed V, a throttle sensor 17 for detecting the opening TVO of the throttle valve 14, and an idle switch which is turned on when the throttle valve 14 is almost fully closed. 18 and a brake switch 19 that is turned on when the brake pedal 13 is depressed, and an automatic transmission based on these sensors, various signals input from the switches, and the current traveling speed of the vehicle. 6 is provided with a CPU 40 as a control unit for outputting a shift signal to the shift unit 20.

The CPU 40 has a ROM in which programs are stored, and a RAM in which data and maps are stored.
This RAM stores a normal shift map as shown in FIG. Next, the system configuration of the automatic transmission 6 will be described with reference to the AT skeleton shown in FIG. 3 and FIG.

As shown in FIG. 3, the automatic transmission 6 is provided with a torque converter 21 and a multi-stage transmission gear mechanism 22. The torque converter 21 includes a pump 2 mounted in a case 24 connected to the engine output shaft 23 and integrally rotating with the engine output shaft 23 to discharge hydraulic oil.
5, a turbine 26 disposed to face the pump 25 and driven to rotate by hydraulic oil discharged from the pump 25, and a flow of hydraulic oil between the pump 25 and the turbine disposed between the pump 25 and the turbine 26. Is provided.

The stator 27 includes a one-way clutch 28
Through the transmission case 29. And
The rotation of the turbine 26 is controlled by a pipe-shaped turbine shaft 30.
Through the transmission gear mechanism 22. Further, the torque converter 21 is provided with a lock-up clutch 31 for directly connecting the engine output shaft 23 and the turbine shaft 30 (including a slip state) in accordance with an operation state.

The engine output shaft 23 is connected to a shaft 32 penetrating through a hollow portion of the turbine shaft 30, and the shaft 32 drives an oil pump 33 to rotate. The transmission gear mechanism 22 includes:
A planetary gear system 34 is provided. The planetary gear system 34 includes a turbine shaft 30.
A small sun gear 35 that is loosely fitted on the turbine shaft 3 at the rear (left side in FIG. 2) of the small sun gear 35.
0 and a plurality of short pinion gears 37 (1) meshing with the large sun gear 36 and the small sun gear 35.
And a long pinion gear 38 and a short pinion gear 3 whose front (the right side in FIG. 2) meshes with the short pinion gear 37 and whose rear meshes with the large sun gear 36.
A carrier 39 that rotatably supports the gear 7 and the long pinion gear 38 and a ring gear 41 that meshes with the long pinion gear 38 are provided. Here, the ring gear 4
1 is connected to the output gear 42.

Various frictional engagement elements are provided for switching the power transmission path in the planetary gear system 34, that is, for switching the gear ratio (gear stage) or forward / reverse travel. More specifically, a forward clutch 43 and a first one-way clutch 44 are interposed between the turbine shaft 30 and the small sun gear 35 in series, and a coast clutch 45 is connected in parallel with the clutches 43 and 44. It is interposed so that it becomes.

Coast clutch 4 as third friction element
5 is provided radially outward with a 2-4 brake 48 including a brake drum 46 connected to the large sun gear 36 and a brake band 47 wound around the brake drum 46. Also, 2 as the first friction element
A reverse clutch 49 that turns on and off power transmission between the brake drum 46 (large sun gear 36) and the turbine shaft 30 is provided behind the −4 brake 48. Further, the carrier 39 and the transmission case 29
, A low reverse brake 50 and a second one-way clutch 51 are interposed in parallel.
A 3-4 clutch 52 as a second friction element is interposed between the turbine shaft 9 and the turbine shaft 30.

In such a transmission gear mechanism 22,
Clutches 43, 45, 49, 52 and brakes 48,
By switching 50 ON and OFF patterns,
The power transmission path in the planetary gear system 34 is switched to obtain four forward speeds and one reverse speed. Then, during driving, the optimum gear position is automatically set according to the range selected by the selection operation and the driving state of the vehicle.

FIG. 5 shows the relationship between each shift speed and the operating states of the clutches 43, 45, 49, 52 brakes 48, 50 and one-way clutches 44, 51 corresponding to the shift speeds. Next, a control configuration of the lock-up clutch 31 will be described with reference to FIG.

As shown in FIG. 4, the lock-up clutch 31 is provided between the converter cover 53 connected to the engine output shaft 23 and the turbine 26 when viewed in the axial direction of the turbine shaft 30 (the left-right direction in FIG. 1). A torsion damper 54 and a damper piston 55 that are arranged between the turbine shaft 30 and rotate integrally with the turbine shaft 30, and a friction plate (not shown) attached to the converter cover 53 at a position facing the damper piston 55. I have.

The damper piston 55 divides the space formed in the converter cover 53 into a rear chamber 56 located on the turbine 26 side and a front chamber 57 located on the converter cover 53 side. Here, the hydraulic pressure in the rear chamber 56 is an operating pressure in the lock-up strengthening direction acting in the direction of pressing the damper piston 55 against the friction plate, and the hydraulic pressure in the front chamber 57 is a direction for separating the damper piston 55 from the friction plate. Operating pressure in the lock-up release direction.

The damper piston 55 is connected to the rear chamber 5
6. Friction engagement with the friction plate or release from the friction plate with a fastening force corresponding to the hydraulic pressure difference between the front chambers 57. That is, the lock-up clutch 31 is completely released in accordance with the oil pressure difference between the two chambers 56.57, and the rotation of the engine output shaft 23 is transmitted to the turbine shaft 30 via the pump or the working oil in the turbine 26. Converter mode (torque increase), lock-up clutch 31 is completely engaged (without slipping), and lock-up mode in which rotation of engine output shaft 23 is directly transmitted to turbine shaft 30. Is in a semi-fastened state (slip state) in which it is engaged with the friction plate while sliding, the rotation of the engine output shaft 23 is transmitted to the turbine shaft 30 via the hydraulic oil, and the turbine is also transmitted through the lock-up clutch 31. Three types of transmission modes, ie, the slip mode transmitted to the shaft 30, are obtained.

A hydraulic circuit 58 is provided for switching the transmission mode of the lock-up clutch 31 and controlling the engagement force in the slip state. This hydraulic circuit 58
A shift valve 59 for switching the hydraulic pressure supply path, a control valve (lock-up valve) 60 for adjusting the hydraulic pressure supplied to the front chamber 57 via the shift valve 59, and an ON / OFF control of the first pilot pressure. A solenoid valve 61 for controlling the solenoid valve, a duty solenoid valve 62 for duty-controlling the second pilot pressure, and a CPU 40 for controlling both solenoid valves 61, 62 are provided.

In the hydraulic circuit 58, a torque converter line 63 (torque converter line (hereinafter simply abbreviated as torque converter line)) into which the line pressure output from the pressure regulator valve 82 (see FIG. 6) is introduced, and a first pilot A first pilot line 64 for supplying pressure;
A second pilot line 65 for supplying pilot pressure;
A line 66 for supplying a constant pressure to the shift valve 59, a line 67 connecting the port 59R of the shift valve 59 and the rear chamber 56, and a line 68 connecting the port 59F of the shift valve 59 and the front chamber 57 are provided. Have been.

The torque converter line 63 has two lines 69,
The line 70 is connected to one of the lines 69 connected to the port 59A of the shift valve 59, and the other line 70 is connected to the port 60A of the control valve 60. The port 60F of the control valve 60 is connected to the port 59B of the shift valve 59 via a line 71. The port 59C of the shift valve 59 is connected to a line 73 leading to the oil cooler 72.

The first pilot line 64 branches into two lines 74 and 75, one of which is connected to a port 59D of the shift valve 59 and the other of which is connected to a port 60B of the control valve 60. I have. And a drain line 75 branched from the line 74
D is provided with a solenoid valve 61. here,
When the solenoid valve 61 is in the OFF state, the drain line 75 is closed, and when the solenoid valve 61 is in the ON state, it is drained.

The second pilot line 65 branches into two lines 76 and 77, one of which is connected to the port 59E of the shift valve 59, and the other of which is connected to the port 60C of the control valve 60. I have. A duty solenoid valve 62 is provided on a drain line 78 branched from the second pilot line 65. Duty solenoid valve 62 is off
In the state, the drain line 78 is closed, and in the ON state, the drain line 78 is drained. In the intermediate region, a second pilot pressure is formed in the second pilot line 65 according to the duty ratio, and the second pilot pressure decreases as the duty ratio increases.

In the shift valve 59, the operation of the two spools according to the pilot pressure causes the port 59 to operate.
Switching of the communication state between R and the port 59A or the port 59C and switching of the communication state between the port 59F and the port 59B or the drain port are performed. In the control valve 60, the port 60F and the port 60F are operated by the operation of the spool according to the pilot pressure.
Switching of the communication state between A and the drain port is performed. Reference numeral 79 denotes a line for guiding hydraulic oil in the torque converter 21 to the oil cooler 72 via the check valve 80.

The switching between the three transmission modes of the lock-up clutch 31 (converter mode, lock-up mode, slip mode) is performed by the CPU 40 in accordance with the operating state. Specifically, the process is executed based on the normal shift map shown in FIG. This map shows the vehicle speed on the horizontal axis and the throttle opening on the vertical axis. In the area on the left side of the left virtual line shown in FIG. In the area on the right side of the right virtual line shown in FIG. 2, the lock-up ON lock-up state is controlled, and in the area hatched in FIG. 2, the slip-up state is controlled.

Although only the hydraulic circuit 58 related to the lock-up clutch 31 is shown in FIG. 4, the operation of the 2-4 brake 48 and other various friction elements will be described with reference to FIGS. The overall configuration of a hydraulic circuit 58 as a working oil supply / discharge means for supplying / discharging oil will be described. The hydraulic circuit 58 is shown separately in FIGS. 6 and 7 for convenience of illustration. The hydraulic circuit 58 related to the lock-up clutch 31 is as shown in FIG.
FIG. 7 schematically shows this.

The hydraulic circuit 58 includes an oil pump 33
A pressure / regulator valve 82 is provided for adjusting the pressure of the hydraulic oil discharged to the main line 81 to a predetermined line pressure. The throttle valve 14 of the engine 5 is located near the pressure regulator valve 82.
A throttle valve 83 for generating a throttle pressure corresponding to the opening degree of the throttle valve, a throttle modulation valve 84 for adjusting the throttle pressure, and a line pressure generated by the above-described pressure / regulator valve 82 are used when the S range and the L range are selected. A backup valve 85 for generating a backup valve pressure for increasing the pressure is provided.

Further, the hydraulic circuit 58 has a pressure
A manual valve 86 for selectively sending the line pressure generated by the regulator valve 82 to each hydraulic line according to the selected range, and a line pressure is selectively supplied to each friction element by operating according to the gear position. 1-2
-3, 3-4 shift valves 87.88.89 are provided.

The manual valve 86 is connected to the main line 8
It has an input port f into which line pressure is introduced from 1 and first to fifth output ports a to e.
The input port f is connected to the first, second, and third output ports a, b, and c in the D range, and to the fifth output port c in the R range. The first to fifth output lines 91 are respectively connected to the output ports a to c.
To 95 are connected.

The 1-2, 2-3, and 3-4 shift valves 87, 88, and 89 respectively urge the spool to the right in the drawing by a spring, and a control port 87a is provided on the right side of the spool. , 88a, 89a. A first control line 96 branched from the main line 81 is connected to the control port 87a of the 1-2 shift valve 87 by the 2-3, 3-4 shift valve 88,
The first output line 8 is connected to the control ports 88a and 89a of the 89.
The second and third control lines 97 and 98 branched from 1 are respectively connected, and these control lines 96 and 9 are connected.
7, 98 are provided with first, second, and third solenoid valves SOL1, SOL2, and SOL3, respectively.
These solenoid valves SOL1 to SOL3 are O
At the time of FF, the control pressure is introduced into the control ports 87a, 88a, 89a of the shift valves 87, 88.89,
The spool is positioned on the left side in the drawing, and when ON, the control pressure in the control ports 87a to 89a is drained to position the spool on the right side.

Here, these solenoid valves SOL
1 to 3 are controlled to be ON and OFF in accordance with the gear to be set according to the vehicle speed of the automobile and the throttle valve opening of the engine. Each solenoid valve SOL1 at each gear in the travel range is set. The combination patterns of ON and OFF of No. to No. 3 are set as shown in FIG.

On the other hand, among the first to fifth output lines 91 to 95 connected to the respective output ports a to c of the manual valve 86, the main valve 81 is communicated with each of the forward ranges D, S and L. The first output line 91 is connected to the forward clutch 43 through a one-way orifice 90.
Is led to. Therefore, the forward clutch 43 is always engaged in the D, S, and L ranges. Note that the first output line 91 is provided with an ND accumulator A1 for buffering when the forward clutch is engaged.

A line 99 is branched from the first output line 91 and led to the 1-2 shift valve 87. The branch line 99 is connected to the spool by turning on the first solenoid valve SOL1. Is moved to the right side, it is communicated with the servo apply line 101 which reaches the hydraulic apply chamber 100b (first hydraulic chamber) of the servo release device 100 of the 2-4 brake 48. Therefore, in the D, S, and L ranges, the first solenoid valve SOL1 is
At the time of N, ie, at the second, third and fourth speeds in the D range, the second and third speeds of the S range, and the second speed of the L range, the servo apply pressure is introduced into the above-described apply chamber 100b. Conversely, if the solenoid SOL1 is OFF, no servo apply pressure is introduced into the apply chamber 100b.

Next, the internal configuration of the servo release device 100 for operating the above-described 2-4 brake 48 will be described.
The servo release device 100 has a 2-4 brake 48
, A hydraulic apply chamber 100b (first hydraulic chamber) as a fastening-side oil chamber and a hydraulic release chamber 100c (second hydraulic chamber) as a release-side oil chamber partitioned by the piston 100a on the left and right in the figure. And a spring compressed in the hydraulic release chamber 100c to bias the piston 100a toward the hydraulic apply chamber 100b.

The piston 100a is formed such that its pressure receiving area is larger in the hydraulic release chamber 100c and smaller in the hydraulic apply chamber 100b, and the difference in the pressure receiving area causes the fastening pressure of the hydraulic apply chamber 100b ( Regardless of the operation or non-operation of the line pressure), if the release pressure (line pressure) acts on the hydraulic release pressure 100c, the piston 100a is moved leftward in the drawing by the release pressure,
The 2-4 brake 48 is configured to operate to the release side. On the other hand, at the time of requesting engagement of the 2-4 brake 48, the piston 100a is moved rightward in the drawing by introducing the engagement pressure into the hydraulic apply chamber 100b and discharging the release pressure of the hydraulic release chamber 100c. -4 brake 48
Is concluded.

A one-way orifice 102 is provided in a line 101 serving as a fastening passage communicating with the hydraulic apply chamber 100b of the servo release device 100 described above. The one-way orifice 102 includes a throttle 102b having an opening 102a having an area smaller than the opening of the line 101, and a spring for urging the throttle 102b downstream (toward the servo release device 100). I have.

Therefore, the one-way orifice 102
Is the hydraulic apply chamber 100 of the servo release device 100
When the oil is discharged from the hydraulic apply chamber 100b, the spring is normally contracted by the oil pressure and the throttle portion 102b is unseated, so that the throttle effect is eliminated. Thus, the above-described spring has a relatively strong urging force, and during a deceleration operation of the engine, the line pressure (the fastening pressure supplied to the servo release device 100) also decreases with a decrease in the throttle valve opening. When the pressure is equal to or less than the value corresponding to the set throttle valve opening value of the low opening, the urging force is set to the urging force value for overcoming the fastening pressure and seating the throttle portion 102b, and the fastening force is set by this configuration. When the value is equal to or less than the value, the fastening pressure is exhausted while the line 101 is narrowed.

Then, the above-described one-way orifice 10
In the line 103 downstream of the servo release device 1,
An accumulator A2 on the piston side that suppresses a sudden rise in the fastening pressure to the hydraulic application chamber 100b at 00 is disposed. The accumulator A2 includes a piston 104 and a line 103
And an oil chamber 105 for moving the piston 104 in the left direction in the figure by flowing in the oil, and a spring compressed in the oil chamber 105. The line pressure is applied to the piston 104 via a line 106 as a back pressure. Working.

The urging force of the spring is set to a large value, and by moving the piston 104 from the stage where the hydraulic pressure of the line 103 is small by the amount of the force,
The configuration is such that the piston 100a of the servo release device 100 is gradually moved, and the 2-4 brake 48 is gently engaged. The above is the description of the servo release device 100 that drives the 2-4 brake 48 and the circuit components around it.

On the other hand, the second output line 92 communicating with the main line 81 in the D and S ranges is connected to the 2-3 shift valve 8.
8 The line 92 is connected to the 3-4 clutch line 108 which leads to the actuator of the 3-4 clutch 52 via the one-way orifice 107 when the second solenoid valve SOL2 is OFF and the spool is located on the left side. Therefore, when the second solenoid valve SOL2 is OFF in the D and S ranges, that is, the 3-4 clutch 52 is engaged at the 3rd and 4th speeds of the D range and the 3rd speed of the S range. The 3-4 clutch line 108 has a bypass valve 109 and a 2-3 timing valve 1 in parallel with the one-way orifice 107.
10 is provided to adjust the engagement timing of the 3-4 clutch 52, and the 3-4 clutch line 108 is also provided with a 2-3 accumulator A3 for buffering when the 3-4 clutch is engaged. .

Further, the above-described 3-4 clutch line 10
8 and a line 112 branched from the first output line 91 are led to a 3-4 shift valve 89. When the third solenoid valve SOL3 is OFF and the spool is on the left side,
Line 111 branched from four clutch line 108
Is connected to a servo release line 114 extending to the hydraulic release chamber 100c of the servo release device 100 via the one-way orifice 113, and a line 112 branched from the first output line 91 is connected to another one-way orifice 1.
15 are connected to a coast clutch line 116 extending to the coast clutch 45 via the respective clutch clutch lines 116.

Therefore, when both the second and third solenoid valves SOL2 and SOL3 are OFF in the D and S ranges,
That is, at the 3rd speed of the D range and the 3rd speed of the S range,
When the servo release pressure is introduced into the hydraulic release chamber 100c of the servo release device 100, the 2-4 brake 48 is released, and when the third solenoid valve SOL3 is OFF in the D, S, and L ranges, that is, when the third solenoid valve SOL3 is in the D range, Speed, S
3rd speed in the range, 2nd speed in the L range, 2nd speed and 3rd speed when operating the hold switch in the S range, L
1st gear and 2nd gear when the range hold switch is operated
At the high speed, the coast clutch 45 is engaged.

Here, the 3-4 clutch line 108
3-2 timing valves 119 and 3 for adjusting the discharge timing of the 3-4 clutch pressure and the servo release pressure via respective branch lines 117 and 118 between the line 111 and the line 111 branched from the line 108. -2
A capacity valve 120 is provided. Also,
The above-mentioned coast clutch line 116 is provided with a bypass line 121 that bypasses the one-way orifice 115, and is provided with a 3-4 capacity valve 122 that opens and closes this line 121. The valve 122 is operated when the 3-4 clutch pressure is generated and when the manual valve 86 is selected to the S range or the L range and the third output line 93 is connected to the main line 81. Bypass line 12
1 is opened to adjust the coast clutch pressure discharge timing.

A fourth output line 94 connected to the main line 81 in the L range by the manual valve 86
Is led to a 1-2 shift valve 87 via a low-reduce valve 123 and a line 124. The line 124 is communicated with a low reverse brake line 127 extending to the low reverse brake 50 via the one-way orifice 125 and the shuttle valve 126 when the first solenoid valve SOL1 is OFF and the spool is located on the left side. Therefore, when the first solenoid valve SOL1 is OFF in the L range, that is, at the first speed in the L range, the low reverse brake 50 is engaged.

Further, the fifth output line 95 communicating with the main line 81 in the R range is connected to the one-way orifice 1.
28 and the shuttle valve 126 and the low / reverse brake line 127 described above, and the one-way orifice 1
A reverse clutch line 130 that branches to the reverse clutch 49 via 29 is branched.

Therefore, in the R range, the low reverse brake 50 and the reverse clutch 49 are always engaged. The reverse clutch line 130 is also provided with an NR accumulator valve A4 for buffering when the reverse clutch is engaged. The line 131 branched from the fifth output line 95 is led to the pressure increasing side of the pressure regulator valve 82 so as to increase the line pressure in the R range.

In addition to the above configuration, the hydraulic circuit 58 is provided with a control valve (lock-up valve) 60 for operating the lock-up clutch 31 in the torque converter 21 described above. A torque converter line 63 is guided from the pressure regulator valve 82 to the valve 60. The configuration of the hydraulic circuit 58 related to the lock-up clutch 31 described above is as described with reference to FIG.

As described with reference to FIG. 8, in the transmission of this embodiment, the solenoid valve SOL for the third speed is set.
Patterns 1 to 3 are XXX (all off). on the other hand,
FIG. 9 shows the first solenoid valves SOL1 and SOL2 for 1-2.
3 illustrates all the solenoid patterns that the second solenoid valve SOL2 for -3 and the third solenoid valve SOL3 for 3-4 can logically take.

According to FIG. 9, the third speed is also possible by the second pattern XX and the fourth pattern XX in addition to the first pattern XXX. This is because the two chambers 100b,
100c, the hydraulic supply chamber 10
This is because, regardless of whether the engagement pressure (line pressure) is 0b or not, if the release pressure (line pressure) acts on the hydraulic release chamber 100c, the 2-4 brake 48 is operated to the open side. . For the third speed, among the three possible patterns, the solenoid pattern in which the hydraulic pressure is not supplied to the hydraulic apply chamber 100b of the servo release device 100 and the hydraulic pressure is supplied to the hydraulic release chamber 100c is XX.
X (all off).

The control device for an automatic transmission according to this embodiment includes a plurality of friction elements (see the respective elements 43 to 45 and 48 to 52). Transmission means (see the transmission gear mechanism 22) for switching the power transmission path between the vehicle and the rear wheels (see rear wheels 3 and 4), and driving state detection means for detecting the driving state of the vehicle including at least the gradient of the traveling path of the vehicle (see FIG. (See the flowchart of 10)
Transmission control means (CPU 4) for controlling the engagement state of the plurality of friction elements based on the detection result of the operation state detection means.
0), and the shift control means (see CPU 40) controls the engagement state of the above-described plurality of friction elements to perform a downshift when the downhill gradient of the traveling path of the vehicle is equal to or more than a predetermined value. During a downshift that is based on the descent gradient being equal to or greater than a predetermined value, of the plurality of friction elements, the drive wheels (the rear wheels 3, 3) are changed from an open state to an engaged state by the downshift. 4), a specific frictional element (see coast clutch 45) enabling transmission of power from the engine 5 to the engine 5 is configured to temporarily operate in the opening direction when a predetermined time has elapsed after the start of engagement. .

Further, under the control of the CPU 40, the pressure is supplied to the third speed coast clutch 45 at the time of the 4-3 shift command at the time of the downhill judgment with the throttle fully closed, no servo apply pressure, and there is a servo release pressure. -4 Output a pattern with clutch pressure (see solenoid pattern No. 1 in FIG. 9), and when a rise in turbine speed Nt (see FIG. 23) is detected, set time ta (see FIG. 23) A pattern with no pressure supply to the clutch 45, no servo apply pressure, no servo release pressure, and a 3-4 clutch pressure is output.
After that, it is configured to output the pattern at the 3rd gear steady state (see the solenoid pattern No. 2 in FIG. 9), and the coast clutch 4 is changed by changing the solenoid pattern.
5 to reduce the shift shock at the time of downhill determination and reduce the uncomfortable feeling given to the driver.

That is, as the plurality of friction elements,
A hydraulic chamber (apply chamber 100b) and a second hydraulic chamber (release chamber 100c) are provided, and are engaged only when the operating pressure is supplied only to the first hydraulic chamber, and are applied to both the first and second hydraulic chambers. A first friction element that is released when the operating pressure is supplied, when the operating pressure is supplied only to the second hydraulic chamber, and when the operating pressure is not supplied to both the first and second hydraulic chambers; (See 2-4 brake 48), a second friction element (see 3-4 clutch 52) which includes a third hydraulic chamber, and is engaged only when the operating pressure is supplied to the third hydraulic chamber. A third friction that includes four hydraulic chambers and is engaged only when the operating pressure is supplied to the fourth hydraulic chamber, and enables the transmission of power from the drive wheels 3 and 4 to the engine 5 by engaging. (See Coast Clutch 45), and the above-described shift control means (see CPU 40). A hydraulic oil supply / discharge means (see hydraulic circuit 58) for adjusting supply / discharge of hydraulic oil to / from each of the first, second, third, and fourth hydraulic chambers, and a shift set in advance according to the operation state. Control means (see CPU 40) for controlling the hydraulic oil supply / discharge means based on the characteristics (see the map in FIG. 2) and the detection result of the operating state detection means (see routine R1 in FIG. 10); Is a first gear (4th speed) in which operating pressure is supplied to the first hydraulic chamber and the fourth hydraulic chamber and hydraulic oil is not supplied to the second hydraulic chamber and the third hydraulic chamber;
In addition, when the descending gradient of the traveling path of the vehicle is equal to or more than a predetermined value, the first, second, third, and fourth hydraulic chambers are supplied with hydraulic oil from the first shift stage (fourth speed). The second gear on the lower gear side than the gear
In order to shift to the third gear, the hydraulic oil supply / discharge means (see the hydraulic circuit 58) is controlled, and during the shift (4-3 downshift) based on the fact that the down slope is equal to or higher than the predetermined value. (Medium), it is configured to control the hydraulic oil supply / discharge means (see the hydraulic circuit 58) so as to temporarily discharge the operating pressure from the fourth hydraulic chamber.

A torque converter 21 is provided between the engine 5 and the speed change means (see the speed change gear mechanism 22), and the control means (see the CPU 40) operates at the first speed (fourth speed) and the vehicle. When the downward slope of the traveling road is equal to or greater than the predetermined value, a shift signal for shifting to the second shift stage (third speed) is output (see S3 in FIG. 22), and based on the shift signal, hydraulic oil supply / discharge means is provided. (See the hydraulic circuit 58), and from the output of the shift signal until the turbine speed Nt of the torque converter 21 reaches a predetermined speed at which the speed change has not been completed by the speed change (see FIG. 23). During the time ta), the hydraulic oil supply / discharge means (see the hydraulic circuit 58) is operated so that the operating pressure is discharged from the fourth hydraulic chamber of the coast clutter 45 (the solenoid pattern No. 4 is executed in step S8 in FIG. 22). It is configured to control.

The operation of the control device for an automatic transmission configured as described above will be described in detail below. First, the downhill determination control will be described with reference to the flowchart shown in FIG. 10 and FIGS. First, in a first step U1, the CPU 40 outputs a brake ON / OFF signal, an idle switch ON, OF
After reading various signals such as the F signal and the vehicle speed, in a second step U2, the current travel speed G of the vehicle is determined from the latest speed change signal output to the speed change unit 20 based on the speed change map of FIG. After reading, the gradient g of the traveling road surface is calculated in a third step U3.

The gradient value g calculated in the above-mentioned third step U3 is determined according to the gradient of the road surface on which the vehicle is traveling, and is 0 on a flat road and 0 on a downhill road (downhill). It becomes a negative value and becomes smaller as the road surface gradient becomes steeper. The following fourth step U4 to seventeenth step U17 are routines for determining whether the vehicle is traveling on a flat road or a downhill road.
In step 4, the absolute value of the gradient value g is equal to a predetermined first gradient predetermined value K.
1 (see FIG. 11). That is, it is determined whether or not the vehicle is traveling on a downhill with a certain gradient. In this case, the first gradient predetermined value K1 is set to be smaller when the gear G is high than when it is low, as shown in FIG. Therefore, it is easier to determine YES in the fourth step U4 when the vehicle is traveling at a high speed.

If the determination in step 4 is YES, the process proceeds to step 5 where the gradient flag Fg is set to 1
And when the determination is NO, the process proceeds to the sixth step U6 where the absolute value of the gradient value g is set to the predetermined second gradient predetermined value K2.
(See FIG. 11) It is determined whether or not: That is, it is determined whether the vehicle is traveling on a flat road with almost no gradient.
Note that the second predetermined value K2 is, as shown in FIG.
It is set to a value close to 0, which is smaller than the predetermined value K1. If the absolute value of the gradient value g is equal to or smaller than the second predetermined value K2, the process proceeds to the seventh step U7 to reset the gradient flag Fg to 0, whereas in the case of NO, that is, the absolute value of the gradient value g is equal to the first value. If it is between the predetermined value K1 and the second predetermined value K2, the process moves to the next eighth step U8.

As a result, a hysteresis is provided between the predetermined values K1 and K2. When it is determined that the vehicle is traveling on a downhill with a certain gradient, the gradient flag Fg is set to 1. On the other hand, when it is determined that the vehicle is traveling on a flat road with almost no gradient, the flag is reset to 0. However, when the degree of the road surface gradient is intermediate between these, the flag Fg is not updated and the previous state is not changed. Is maintained, the switching hunting of the gradient flag Fg is prevented.

Next, in an eighth step U8, it is determined whether or not the idle switch 18 is ON. That is, accelerator pedal 1
It is determined whether or not 5 is depressed. When the determination is YES, the process proceeds to the next ninth step U9, in which the vehicle speed V read in the above-described first step U1 is stored as the idling vehicle speed Vi. This idle vehicle speed Vi is continuously updated while the accelerator pedal 15 is not depressed, and when the accelerator pedal 15 is depressed, the eighth step U8 to the eleventh step U11 are performed as described later.
The update of the idle vehicle speed Vi is stopped. Therefore, the idle vehicle speed Vi remains as the vehicle speed immediately before the accelerator pedal 15 is depressed, that is, the vehicle speed when the accelerator pedal 15 is depressed.

On the other hand, if NO is determined in the eighth step U8, that is, if the accelerator pedal 15 is depressed, the flow shifts to the eleventh step U11 to count the timer t by t + 1. The timer t continues to be counted while the accelerator pedal 15 is depressed, and is cleared in a tenth step U10 following the ninth step U9 when the accelerator pedal 15 is not depressed. Therefore,
This timer t measures the time from when the accelerator pedal 15 is depressed.

Next, when the accelerator pedal 15 is not depressed, the first step U10 is performed following the tenth step U10.
Steps U12 to U15 will be described. This is a routine for determining whether or not the downhill determination flag F is set to 1. First, it is determined whether or not the brake switch 19 in the twelfth step U12 is ON. That is, it is determined whether or not the brake pedal 13 is depressed.

When the determination is YES, the thirteenth step U
13 and the deceleration of the vehicle becomes the predetermined value A (see FIG. 12).
It is determined whether or not this is the case. That is, it is determined whether or not the vehicle has significantly decelerated to the predetermined value A or more due to the depression of the brake pedal 13. In this case, as shown in FIG. 12, the predetermined deceleration value A is set to be smaller when the gear G is high than when it is low. Therefore, the thirteenth time when traveling at the high speed
It becomes easy to make a YES determination in step U13. Y
At the time of ES determination, in the fourteenth step U14, the state of the gradient flag Fg is checked, and if this is set to 1,
In other words, when the vehicle is traveling on a downhill road, the following first
The program proceeds to step U15, in which the downhill determination flag F is set to 1.

However, these steps U12, U
13 or U14, when the brake pedal 13 is not depressed, the vehicle is not greatly decelerated to a predetermined value A or more, or the gradient flag Fg is reset to 0, the downhill determination flag F is set to 1 Skip to another nineteenth step U19 without going through the fifteenth step U15.

That is, the downhill determination flag F is set to 1 only when the vehicle is traveling on a downhill road and the brake pedal 13 is depressed and the vehicle is greatly decelerated to a predetermined value A or more. You. Also, the above-mentioned eighth step U8
When the accelerator pedal 15 is depressed, the steps U12 to U15 for determining whether or not to set the downhill determination flag F to 1 are executed without executing the steps U12 to U15. skip.

Next, at a sixteenth step U16, after reading the shift speed G determined from the shift map of FIG.
In steps U17 and U18, predetermined values Fv and Ft for determination are set, respectively. The predetermined value Fv set in the seventeenth step U17 is
22, a value obtained by subtracting the vehicle speed Vi when the accelerator pedal 15 is depressed from the vehicle speed V, that is, the accelerator pedal 1
5 is a predetermined value (hereinafter referred to as "predetermined vehicle speed value") used to determine the magnitude of the increase in vehicle speed from when the vehicle is depressed.

The vehicle speed predetermined value Fv is, as conceptually shown in FIG. 13, the vehicle speed V when the accelerator pedal 15 is depressed.
i, the absolute value of the gradient value g, and the actual value are assigned to a map of a value f1 which is a function for each of the gears G to determine a corresponding value f1.
v. In this case, the function value f1 is larger when the vehicle speed Vi is high when the accelerator pedal 15 is depressed than when it is low, as shown in FIG.
Also, as shown in FIG. 15, the setting is made such that when the absolute value of the gradient value g is large, it is larger than when it is small, and as shown in FIG. 16, when the speed G is high, it is larger than when it is low. Have been. Accordingly, when the vehicle speed Vi when the accelerator pedal 15 is depressed is high, when the vehicle is traveling at a high grade, and when the vehicle is traveling at a high speed, the increase in the vehicle speed is not relatively large. It becomes difficult to determine YES.

On the other hand, the predetermined value Ft set in the above-mentioned eighteenth step U18 is a predetermined value (hereinafter referred to as "the following value" used for judging the length of time t from when the accelerator pedal 15 is depressed in the twenty-third step U23. The time is referred to as “predetermined value”. As shown conceptually in FIG. 17, the predetermined time value Ft is a map of a value f2 which is a function for each of the throttle opening TVO, the absolute value of the gradient value g, and the speed G. Is set by assigning these actual values to the corresponding values f2 and calculating a corresponding value f2, and setting this as a predetermined value Ft.

In this case, the function value f2 is larger when the throttle opening TVO is small as shown in FIG. 18 than when it is large, and the absolute value of the gradient value g is large as shown in FIG. The time is set to be larger than when it is small, and as shown in FIG. 20, it is set to be larger when the gear G is high than when it is low. Therefore, when the throttle opening TVO is small or when the gradient is steep,
When the vehicle is traveling at a high speed, the accelerator pedal 15
If the time t from the stepping on is not relatively long, it will be difficult to make a YES determination in the twenty-third step U23. From the next 19th step U19 to the 23rd step U23,
Whether to reset the downhill determination flag F to 0, or 1
Is a routine for determining whether or not to return to 0 from.

First, in a nineteenth step U19, the gradient flag F is set.
Looking at the state of g, if this is reset to 0,
That is, when the vehicle is traveling on a flat road, the process proceeds to the twentieth step U20, where the downhill determination flag F is reset to 0, and then the process returns to the first step U1. If the vehicle is traveling on a downhill road, the process proceeds to step 21 to determine whether or not the idle switch 18 is ON. When the determination is YES, that is, when the accelerator pedal 15 is not depressed, On the other hand, when the determination is NO, that is, when the accelerator pedal 15 is depressed, the process proceeds to the twenty-second step U22 to determine the above-described increase amount of the vehicle speed. When the determination is YES, that is, when the amount of increase in the vehicle speed from when the accelerator pedal 15 is depressed is greater than the predetermined vehicle speed value Fv set in the seventeenth step U17, the process proceeds to the twentieth step U20, where the downhill determination flag F Is set to 0.

Further, when a negative determination is made in the twenty-second step U22, the flow shifts to a twenty-third step U23 to determine the length of the time t. The time t from the time of YES determination, that is, the time when the accelerator pedal 15 is depressed, is the first time.
When the time set in the step U18 is larger than the predetermined value Ft, the process shifts to the twentieth step U20 to set the downhill determination flag F to 0. That is, the amount of increase in the vehicle speed is equal to the predetermined vehicle speed F.
If the depression time t of the accelerator pedal 15 does not exceed the predetermined time value Ft, the downhill determination flag F is set to 0, and the depression time t of the accelerator pedal 15 is used as a backup for control. ing.

Next, the flow of the shift control will be described with reference to FIG. The first in the flowchart of FIG.
In step P1, the CPU 40 sets the downhill determination flag F to F =
1 or not, and when the determination is NO (when F = 0), the second
On the other hand, when the judgment is YES (when F = 1), the process shifts to another third step P3. The second mentioned above
In step P2, the CPU 40 executes the shift control based on the normal shift map shown in FIG.
The CPU 40 prohibits the fourth speed (3rd speed when running at the fourth speed).
Downshift to high speed).

Next, with reference to the flowchart of FIG. 22 and the time chart of FIG. 23, the downshift control at the time of downhill determination will be described. In the first step S1, the CPU 4
A value of 0 executes detection of reading of the gear G, the throttle opening TVO, the turbine speed Nt, the vehicle speed V, and the downhill determination flag F. Next, in a second step S2, the CPU 40 determines whether or not the downhill determination flag F is 1; when F = 0, the CPU 40 shifts to a thirteenth step S13 on the side of the normal shift control routine; At the time of downhill determination, the process proceeds to the next third step S3.

In the third step S3, the CPU 40 determines whether or not the gear is G = 4 (fourth speed). When the determination is NO, the CPU 40 skips to the above-described thirteenth step S13, while the YE is executed.
When the determination is S, the process proceeds to the next fourth step S4. In the fourth step S4, the CPU 40 responds to the downshift from the fourth speed to the third speed by the solenoid pattern No. 1 (see FIG. 9). That is, when the throttle is fully closed, pressure is supplied to the third speed coast clutch 45 at the time of the 4-3 shift command at the time of descending determination (F = 1), there is no servo apply pressure, there is servo release pressure, and there is 3-4 clutch pressure. A pattern is output, and a coast clutch 45 that enables power transmission between the rear wheels 3 and 4 as drive wheels and the engine 5 is once engaged to apply engine brake.

Next, in a fifth step S5, the CPU 40 determines whether or not the rate of change ΔNt of the turbine speed Nt has become zero or more. That is, as shown in FIG. 23, the turbine rotational speed Nt decreases during deceleration, but if a downshift is performed during deceleration, the turbine rotational speed Nt increases. It is determined whether or not the turbine speed Nt has exceeded zero (see the dotted line β in FIG. 23) for the purpose of determining. The process returns when the determination is NO, whereas the process proceeds to the next sixth step S6 when the determination is YES, and the CPU 4
0 sets the current turbine speed Nt to the turbine speed Nto for determination.

Next, in a seventh step S7, the CPU 40 determines whether or not the determination turbine rotation speed Nto has exceeded a predetermined rotation value α (see FIG. 23). When the determination is NO, the CPU 40 returns to the first step S1. When YES is determined as Nto> α, the process shifts to the next eighth step S8. In the eighth step S8, the CPU 40 determines that the solenoid pattern No. 4
(See FIG. 9). That is, the turbine speed Nt
When the rise is detected, a pattern of no pressure supply to the third speed coast clutch 45, no servo ply pressure, no servo release pressure, and 3-4 clutch pressure is output for a set time ta (see FIG. 23), and the coast pressure is output. And the engine brake is not applied during this set time ta.

Next, in a ninth step S9, the CPU 40 sets the set time ta in the timer T, and in the next tenth step S10, the CPU 40 decrements the timer T by T-1.
I do. Next, in an eleventh step S11, the CPU 40 determines whether or not the sequentially decremented timer T has become zero. When the determination is NO, the CPU 40 returns to the eighth step S8, while the determination is YES (when T = 0). Shifts to the next twelfth step S12. Solenoid pattern No. 4 (see FIG. 9) for releasing the coast pressure is executed only during the set time ta set in advance by the processes of steps S8 to S11 described above.

Next, in a twelfth step S12, after the elapse of the set time ta, the CPU 40 sets the solenoid pattern N
o. Execute 2 (see FIG. 9). That is, a pattern at the third speed steady state with the servo apply pressure, the servo release pressure, and the 3-4 clutch pressure is output. On the other hand, in a thirteenth step S13, the CPU 40 selects the shift speed G from the normal shift map of FIG. Next, in a fourteenth step S14, the CP
U40 determines whether or not the shift speed is G = 1. If the determination is NO, the process proceeds to the sixteenth step S16, while if the determination is YES, the process proceeds to the next fifteenth step S15.

In the fifteenth step S15, the CPU 40
Executes solenoid pattern No. 6 (see FIG. 9) corresponding to the first speed. In the above-described sixteenth step S16, the CP
U40 determines whether or not the gear is G = 2. If the determination is NO, the process proceeds to the eighteenth step S18, while if the determination is YES, the process proceeds to the next seventeenth step S17. This 17th
In step S17, the CPU 40 executes solenoid pattern No. 7 (see FIG. 9) corresponding to the second speed.

In the above-mentioned eighteenth step S18, the CPU 4
If 0, it is determined whether or not the gear is G = 3. When the determination is NO, the process proceeds to the 19th step S19, and when the determination is YES, the process proceeds to the 20th step S20. The above-mentioned nineteenth step S
At 19, the CPU 40 executes the solenoid pattern No. 8 (see FIG. 9) corresponding to the fourth speed, while at the twentieth step S20, the CPU 40 executes the solenoid pattern No. 2 (see FIG. 9) corresponding to the third speed. I do.

In short, according to the control device for an automatic transmission of the present embodiment, the above-described transmission means (see the transmission gear mechanism 22) is in the engagement state of each friction element (see each element 43 to 45, 48 to 52). , The power transmission path between the engine 5 and the drive wheels (see the rear wheels 3 and 4) is switched, and the above-described operating state detecting means (see the routine R1 in the flowchart shown in FIG. 10) at least The driving state of the vehicle including the gradient of the vehicle is detected, and the above-described shift control means (C
PU40) controls the engagement state of the plurality of friction elements based on the detection result of the operation state detection means R1.

Further, the above-described shift control means (CPU 40
When the descending gradient of the traveling path of the vehicle is equal to or more than a predetermined value (the descending is steep), the engagement state of the plurality of friction elements is controlled to perform the downshift, and the descending gradient is equal to or more than the predetermined value. A specific friction element (see coast clutch 45) is temporarily operated in the release direction when a predetermined time has elapsed after the start of engagement during the downshift based on the shift.

As a result, it is possible to reduce the engagement shock due to the engine brake friction element (see the coast clutch 45) without adding any other device, and to suppress the shift shock at the time of downhill determination. .

Further, the engagement is performed only when the operating pressure is supplied to the fourth hydraulic chamber, and the engagement is performed, so that the driving wheels 3, 3 are engaged.
A coast clutch 45 is provided as a third friction element that enables power transmission from the engine 4 to the engine 5, and the operating pressure is supplied from the above-described fourth hydraulic chamber during downshifting based on a descent gradient of not less than a predetermined value. Since the temporary discharge is performed, the engagement shock due to the coast clutch 45 as the third friction element can be reduced, and there is an effect that the shift shock at the time of downhill determination can be suppressed.

Further, a shift signal (for example, a shift signal for 4-3 downshifting) is output (see step S3 in FIG. 22) until the turbine speed Nt of the torque converter 21 reaches a predetermined speed by the speed change. Since the operating pressure is discharged from the fourth hydraulic chamber (during time ta) (solenoid pattern No. 4 is executed in step S8 in FIG. 22), control is performed to discharge the above operating pressure. There is an effect that the time can be set to an appropriate time that does not cause a shift shock.

In addition, the operating pressure is temporarily discharged from the fourth hydraulic chamber during the 4-3 downshift based on the fact that the descending gradient is equal to or more than the predetermined value. Therefore, there is an effect that the shift shock at the time of downhill determination can be suppressed.

In the correspondence between the structure of the present invention and the above-described embodiment, the plurality of friction elements of the present invention correspond to the respective elements 43 to 45 and 48 to 52 of the embodiment. The transmission means corresponds to the transmission gear mechanism 22, the operating state detection means corresponds to the routine R1 (see FIG. 10), the transmission control means corresponds to the CPU 40, and Corresponds to the coast clutch 45, the first hydraulic chamber corresponds to the hydraulic apply chamber 100b,
The second hydraulic chamber corresponds to the hydraulic release chamber 100c,
The friction element corresponds to the 2-4 brake 48, the second friction element corresponds to the 3-4 clutch 52, and the third friction element
Corresponding to the coast clutch 45, the control means is a CPU 4
0, the first gear corresponds to the fourth gear, the second gear corresponds to the third gear, and the hydraulic oil supply / discharge means includes a hydraulic circuit 5.
8, the present invention is not limited to only the configuration of the above-described embodiment.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle including a control device for an automatic transmission according to the present invention.

FIG. 2 Normal shift map

FIG. 3 is a skeleton diagram of an automatic converter.

FIG. 4 is a system diagram of a hydraulic circuit related to a lock-up clutch.

FIG. 5 is an explanatory diagram showing an operation for each range of a clutch and a brake.

FIG. 6 is a circuit diagram showing a part of a hydraulic circuit.

FIG. 7 is a circuit diagram showing another part of the hydraulic circuit connected to the hydraulic circuit of FIG. 6;

FIG. 8 is an explanatory diagram showing states of three solenoids in a hydraulic circuit for each shift speed.

FIG. 9 is an explanatory diagram showing a relationship between a solenoid pattern and a gear position.

FIG. 10 is a flowchart showing a descending slope determination process.

FIG. 11 is an explanatory diagram of a predetermined gradient value.

FIG. 12 is an explanatory diagram of a deceleration predetermined value.

FIG. 13 is a conceptual diagram of a predetermined vehicle speed value.

FIG. 14 is an explanatory diagram of a function value.

FIG. 15 is an explanatory diagram of a function value.

FIG. 16 is an explanatory diagram of a function value.

FIG. 17 is a conceptual diagram of a predetermined time value.

FIG. 18 is an explanatory diagram of a function value.

FIG. 19 is an explanatory diagram of a function value.

FIG. 20 is an explanatory diagram of a function value.

FIG. 21 is a flowchart showing a shift control process.

FIG. 22 is a flowchart showing coast clutch control during downshift control based on downhill determination.

FIG. 23 is a time chart showing coast clutch control during downshift control based on downhill determination.

[Explanation of symbols]

 3.4 Rear wheel (drive wheel) 5 Engine 22 Transmission gear mechanism (transmission means) 40 CPU (transmission control means, control means) 45 Coast coast (third friction element) 48 ... 2-4 brake ( 1st friction element) 52 3-4 clutch (second friction element) 58 hydraulic circuit (hydraulic oil supply / discharge means 100b) hydraulic apply chamber (first hydraulic chamber) 100c hydraulic release chamber (second hydraulic chamber) R1 ... Operating state detection means

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI F16H 63:12

Claims (4)

[Claims] 1. A vehicle comprising a plurality of friction elements, a transmission means for switching a power transmission path between an engine and drive wheels by changing an engagement state of each friction element, and a vehicle including at least a gradient of a traveling path of the vehicle. Operating state detecting means for detecting an operating state of the vehicle, and shift control means for controlling an engagement state of the plurality of frictional elements based on a detection result of the operating state detecting means. When the downward slope is equal to or greater than a predetermined value, the engagement state of the plurality of friction elements is controlled to perform a downshift, and during the downshift based on that the downward slope is equal to or greater than the predetermined value, After a predetermined time has elapsed after the start of engagement of one of the friction elements, the friction element that enables transmission of power from the drive wheels to the engine by being changed from the open state to the engaged state by the downshifting is started. When the control device for an automatic transmission to operate temporarily opening direction. A first hydraulic chamber and a second hydraulic chamber, the first and second hydraulic chambers being engaged only when the operating pressure is supplied only to the first hydraulic chamber; It is released when the operating pressure is supplied to both of the chambers, when the operating pressure is supplied only to the second hydraulic chamber, and when the operating pressure is not supplied to both the first and second hydraulic chambers. A second friction element that includes a first friction element and a third hydraulic chamber, and is engaged only when the operating pressure is supplied to the third hydraulic chamber; and a fourth hydraulic chamber that operates in the fourth hydraulic chamber. A third friction element that is engaged only when pressure is supplied, and that enables the transmission of power from the drive wheels to the engine by engaging the first and second shift control means. Hydraulic oil supply / discharge means for adjusting the supply / discharge of hydraulic oil to / from each of the third and fourth hydraulic chambers; Is provided with a control means for controlling hydraulic fluid supply and discharge means on the basis of the detection result of the shift characteristic and the operating condition detecting means, the control means, the first hydraulic chamber and a fourth
When the operating pressure is supplied to the hydraulic chamber and the hydraulic pressure is not supplied to the second hydraulic chamber and the third hydraulic chamber, and the downshift of the traveling path of the vehicle is equal to or more than a predetermined value. Operating from the first gear to a second gear lower than the first gear in which hydraulic oil is supplied to the first, second, third, and fourth hydraulic chambers. And controlling the hydraulic oil supply / discharge means so as to temporarily discharge the operating pressure from the fourth hydraulic chamber during the shift based on the descent gradient being equal to or more than the predetermined value. 2. The control device for an automatic transmission according to claim 1. 3. A torque converter is provided between the engine and the speed change means, and when the control means is in the first shift speed and the downhill gradient of the traveling path of the vehicle is equal to or higher than the predetermined value,
A shift signal for shifting to the second shift stage is output, the hydraulic oil supply / discharge means is controlled based on the shift signal, and after the shift signal is output, the turbine speed of the torque converter is reduced by shifting. 3. The control device for an automatic transmission according to claim 2, wherein the control unit controls the hydraulic oil supply / discharge unit to discharge the operating pressure from the fourth hydraulic chamber until the rotation speed reaches a predetermined rotation speed that has not been completed. 4. The first shift stage is a fourth shift stage, the second shift stage is a third shift stage, and the first friction element is disengaged at a third shift stage where the first friction element is engaged at the fourth shift stage. The second friction element is engaged at the third speed and the fourth speed.
3. The control device for an automatic transmission according to claim 2, wherein the clutch is a coast clutch in which the third friction element is engaged at a third speed.