JPS61167754A - Hydraulic control device for automatic transmission - Google Patents

Abstract

PURPOSE:To enable prevention of the occurrence of impact during engagement, by a method wherein control of overlap causes prevention of rotation of the portion on the engine side of a frictional engaging device for a low speed step. CONSTITUTION:The servo oil pressure of a clutch 24 for a high speed step crosses the servo oil pressure of a brake 26 for a low speed step, and the brake 26 for a low speed step is increased in volume to a value being high enough to allow for engagement. During down shift of an auxiliary transmission 16 during stop of a vehicle, control of overlap is executed, at least either the clutch 24 for a high speed step or the brake 26 for a low speed step is held in an engaging state even during transmission. This prevents the portion on the engine side of the brake 26 for a low speed step from rotation, and prevents the occurrence of impact during engagement of the brake 26 for a low speed step.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic control system for an automatic transmission, and more particularly to hydraulic control when a sub-transmission is manually switched from a high gear to a low gear.

Conventional technology In order to improve power performance, this is an automatic transmission in which an auxiliary transmission that can be manually switched between high and low gears is connected in series with the main transmission. In automatic transmissions that use clutch-to-clutch (the hydraulic friction engagement device that is engaged is changed), this is used to reduce the impact when downshifting the sub-transmission from a high gear to a low gear. In this case, underlap control is required to delay the engagement timing of the low-speed friction engagement device from the release timing of the high-speed friction engagement device and maintain both friction engagement devices in the released state (for example, underlap control is required). Gansho 59-91071
issue).

However, such underlap control when downshifting the auxiliary transmission is useful for revving up the engine appropriately while the vehicle is moving and mitigating the impact, but when the vehicle is stopped, underlap control does not change the automatic transmission's neutral state. Since the engine side part of the low speed friction engagement device rotates during underlap control, when the underlap control ends and the low speed friction engagement device engages, this engine side portion rotates. There is a problem that the rotation of the machine stops and a shock occurs.

Problems to be Solved by the Invention It is an object of the present invention to provide a hydraulic control device for an automatic transmission that can prevent a shift shock that occurs when a vehicle is stopped due to underlap control during downshifting of an auxiliary transmission. It is to provide.

Means for Solving the Problems In order to achieve this object, the present invention provides a main transmission having a plurality of gears and a sub-transmission connected in series thereto and capable of being manually switched to high and low gears. In a hydraulic control system for an automatic transmission having a transmission, in the case of a downshift of an auxiliary transmission, underlap control is performed when the vehicle is running, but underlap control is not performed when the vehicle is stopped. , overlap control, that is, control is performed in which both the high-speed gear friction engagement device and the low-speed gear friction engagement device are not in the released state, but at least one is in the engaged state.

Effects of the Invention As described above, when the sub-transmission is downshifted while the vehicle is stopped, overlap control is performed, so the engine side portion of the low-speed friction engagement device is prevented from rotating, and the low-speed friction engagement device is prevented from rotating. This prevents the occurrence of shocks when the mating device is engaged.

Example Embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows the overall configuration of the automatic transmission, and in order from the upstream in the power transmission path of the engine, the engine lO1 fluid torque converter 12, the main transmission 14 having a plurality of gears, and the auxiliary transmission. It is equipped with 16. In this figure, the auxiliary transmission 16 is attached to the output shaft of the main transmission 14, but the reverse is also possible, that is, the main transmission 14 is attached to the output shaft of the auxiliary transmission 16. do not have. The auxiliary transmission 16 includes an input shaft 18 coupled to an output element of the main transmission 14, a planetary gear set 20 including a sun gear coupled to the input shaft 18, and an output coupled to a carrier of the planetary gear set 20. It has a high speed clutch 24 that controls the connection between the shaft 22, the input shaft 18, and the carrier of the planetary gear set 20, and a low speed brake 26 that controls the fixation of the ring gear of the planetary gear set 20. When the high speed clutch 24 is engaged, the rotation of the input shaft 18 is transmitted to the output shaft 22 at a reduction ratio l, and when the low speed brake 26 is engaged, the rotation of the input shaft 18 is decelerated and transmitted to the output shaft 22. Ru. The throttle opening sensor 28 detects the throttle opening of the intake passage, the pattern select switch 30 detects the driving pattern selected by the driver such as economy (economic driving), power (output driving), etc., and the shift position sensor 32 is D (drive) selected by the driver,
Detects shift position such as R (reverse) and shifts to L-
The H position switch 34 detects the L (low gear) and H (high gear) positions of the sub-transmission 16 selected by the driver, and the oil temperature sensor 40 detects the oil temperature as a hydraulic medium used in the hydraulic control device 42. The temperature is detected, the oil pressure sensor 44 detects the oil pressure of the high speed clutch 24, and the vehicle speed sensor 46 detects the rotational speed of the output shaft 22, which is proportional to the vehicle speed. CPo 48 receives signals from these sensors and switches as input and controls hydraulic controller 42 based on these signals.

FIG. 3 shows the hydraulic control device 42 of FIG. 2 in detail, and the oil pump 50 sucks oil in the oil pan 52, pressurizes it, and discharges it. The main shift control circuit 54 is
It includes well-known elements such as a shift valve and a primary regulator valve that change the gear stage of the main transmission 14.
I! occurs. The L-H switching valve 60 has ports 62 and 64 connected to the line pressure oil passage 56, and
．． 72, and other ports 68.70, L
-Port or drain 62+ in relation to H position
Controls the connection between 64, 66+68+70, 72. L
The -H switching pulp 60 may be of the type having a spool supplied with a control pressure in relation to the L-H position and moving in relation to this control pressure. High speed clutch 24
is held in an engaged state in the H position and is connected to the port 68 via the oil passage 76. Accumulator 78
is connected to the oil passage 76, and an orifice 80 and a check valve 82 are provided in parallel with each other in the middle of the oil passage 76.

The check valve 82 opens when the oil of the high speed clutch 24 flows toward the port 68, and the low speed brake 26 opens.
It is held in an engaged state at the L position and is connected to the port 70 via an oil passage 86. The accumulator 88 is connected to the oil passage 86, and an orifice 90 is provided in the middle of the oil passage 86.
and a check valve 92 are provided in parallel with each other. The check valve 92 connects the oil of the low speed brake 26 to the port 70.
The discharge oil passage lOO, which opens when the oil flows toward the oil passage, branches from the oil passage 86 between the port 70 and the orifice 90, and guides the oil at the branched point to the drain. The solenoid valve 102 as a solenoid valve includes a solenoid 104 and a valve body 10 that opens and closes the discharge oil path 100 in relation to the solenoid 104.
6, and similarly to the main shift control circuit 54, the CPU
It is controlled by electrical signals from 48.

For the first time, refer to Figure 4 and perform the H→L operation while the vehicle is running.
The underlap control performed by the CPU 48 when the underlap control is performed will be explained.

In FIG. 4, Pc is the servo oil pressure of the high speed clutch 24, and Pb is the servo oil pressure of the low speed brake 26.

Before time t1, the L-H position is at the H (high speed stage) position, and in the L-H switching valve 60, the port 68 is connected to the port 62, and the port 70 is connected to the drain 72, respectively. As a result, the high speed clutch 24 is supplied with oil from the line pressure oil passage 56 and is held in an engaged state, whereas the oil in the low speed brake 26 is discharged and the low speed brake 26 is released. maintained in the state. Therefore, the sub-transmission 16 is in the high speed gear.

At time tl, the L-H position is changed to H by the driver.
position to low gear) position.

By this switching, the control pressure of the L-H switching valve 60 is
48, the spool of the L-H switching valve 60 is switched from a high speed position to a low speed position. Thus port 68 goes to drain 66 and port 70 goes to drain 66.
are connected to the ports 64, respectively, and the servo oil pressure Pc begins to fall.

On the other hand, oil is guided to the port 70 from the line pressure oil passage 56, but the solenoid valve 102 keeps the discharge oil passage 100 open for a predetermined time Ta from time ti, so the servo oil pressure Pb is maintained at zero. , engagement of the low speed brake 26 is prevented.

At time t2, when a predetermined time Ta has elapsed from time tl, solenoid valve 102 closes discharge oil passage 100. As a result, the servo oil pressure Pb starts to rise from time t2, and reaches a predetermined oil pressure at time t3 after time Tb has elapsed from time t2, and the low speed brake 26 enters a half-engaged state.

The period from when the servo oil pressure Pc appropriately decreases until time t3 is an underlap period in which both the high speed clutch 24 and the low speed brake 26 are released, and the engine rotational speed increases smoothly during this underlap period. .

Figure 5 shows the predetermined time T in the underlap control in Figure 4.
It shows the characteristics of a. As the vehicle speed V increases, the amount of increase in engine rotational speed required when switching from the H position to the H position increases, so the predetermined time Ta for lengthening the underlap period also increases. Furthermore, since the required increase amount of the inertial mass and engine rotational speed of the main transmission 14 differs depending on the first to fourth gears of the main transmission 14, the predetermined time Ta is It is also set as a function of the gear position. Note that in FIG. 4, the predetermined time Ta is shorter in the case of the third speed than in the case of the fourth speed, because when the third speed is a reduction ratio l and the fourth speed is overdrive, This is because the inertial mass at high speed is smaller than that at fourth speed. Furthermore, as the temperature T of the oil decreases, the viscosity of the oil increases, and the speed of oil supply to the low speed brake 26 decreases, so that
By setting a to a shorter value as the oil temperature T decreases, it is possible to compensate for the deviation in the underlap period due to the oil temperature T. Also, as the throttle opening θ increases, the engine speed increases, so the predetermined time Ta is set to a shorter value as the throttle opening θ increases. Therefore, it is possible to compensate for the deviation in the underlap period.

Next, with reference to FIG. 6, the overlap control performed by the CPLJ 48 when the H-+L operation is performed while the 1F is on both stops will be described. In Figure 6, P
c + P b is as defined in FIG. The difference from the underlap control shown in FIG. 4 is that the predetermined time Ta as a control factor for the underlap period is set to zero, and the servo oil pressure Pc of the high speed clutch 24 starts decreasing at the same time as the low speed brake 26. This means that the servo oil pressure Pb starts to rise.

Before time tll, the lever 11 position is in the H position, and the port 68 in the L-H switching valve 60 is in the H position.
2 and port 70 are connected to drain 72, respectively. As a result, the high-speed clutch 24 is supplied with oil from the line pressure oil passage 56 and is held in an engaged state, while the oil in the low-speed brake 26 is discharged and the low-speed brake 24 is maintained in an engaged state. is held free. Therefore, the sub-transmission 16 is in the high speed gear.

At time t11, the L-H position is changed by the driver to ■
It can be switched from position to position. With this switching, L-H
The control pressure of the switching valve 60 is changed by the CPo 48, and the spool of the L-H switching valve 60 is switched from a high speed position to a low speed position. In this way, the port 68 is connected to the drain 66, the port 70 is connected to the port 64, and the servo oil pressure Pc begins to decrease. In addition, oil is introduced to the port 70 from the line pressure oil passage 56, but when the sub-transmission 16 is downshifted while the vehicle is stopped, the time Ta for keeping the solenoid valve 102 open is set to zero. , the solenoid valve 102 is closed at time tll, and the line pressure P7! is the low gear brake 2
6, and the servo oil pressure Pb starts to rise immediately from time tll.

At time t12, the servo oil pressure Pc of the high speed clutch 24 and the servo oil pressure Pb of the low speed brake 26 intersect, and the low speed brake 26 has sufficient torque capacity to engage. In this way, the high speed clutch 24
The low speed brake 26 becomes engaged before the brake 26 becomes released.

After time tlZ, the servo oil pressure Pc of the high speed clutch 24
As the speed further decreases, the output shaft torque of the auxiliary transmission 16 smoothly increases to the value at the lower gear.

In this way, when the sub-transmission 16 is downshifted while the vehicle is stopped, overlap control is performed instead of underlap control, and at least one of the high-speed clutch 24 and the low-speed brake 26 remains engaged even during the gear shift. is held in
Since the engine side portion of the low speed brake 26 does not rotate, generation of impact when the low speed brake 26 is engaged is avoided.

FIGS. 7 and 8 are flowcharts of a speed change control routine according to the control explained in FIGS. 4 and 6.

A flag F1 indicating that the operating position of the sub-transmission 16 has been switched from H to L and a timer that counts the elapsed time Ti from the time when the flag F changes from 0 to 1 are reset as initialization (step 110). , 112). The command gear Sx of the main transmission +4 is calculated based on the vehicle speed V and the intake throttle opening θ (step 114).
The drive side W (on, off) of the main transmission solenoid valve is performed in accordance with this instructed gear speed Sx (step +16).
, the gear position of the main transmission 14 is set to the command gear position Sx. Further, drive control of the sub-transmission solenoid valve is performed according to the operating positions of H and L of the sub-transmission 16 (step 1).
18), the L41 switching valve 60 is in a position corresponding to the operating position. If there is no change in the operating position from H to H (step 120 determines p=Q, step 122 determines No), the process returns to calculating the commanded gear Sx of the main transmission (step 114). When the operating position changes from H to L (YES in step +22), flag F is set (step +24), and the elapsed time is counted by the timer.
Counting of l is started (step 126). Subsequently, the vehicle speed V is read (step 128). If the vehicle speed is not 0 (determination in step 129 is NO), the indicated gear position Sx
, oil temperature T1 and intake throttle opening degree 0 are read (
Step +30. l:121134), these V!
5XIT1131rv-base tweet predetermined time Ta is calculated (step 136). If the vehicle speed is 0 (YES in step 129), the value of Ta is set to 0 to perform overlap control (step 137). Next, compare the elapsed time T1 and the predetermined time Ta in step 138.
), if Ti<Ta, that is, within the predetermined time Ta after the change from II to Shi, turn on the ungrabbing control solenoid valve 102 to open the discharge oil passage 100 (step 140), and if T1≧Ta, If there is, that is, after the predetermined time Ta has elapsed, the underground control solenoid valve 102 is turned off and the discharge oil passage 100 is closed (step 1).
42), and further reset flag F (step 14).
4).

FIG. 1 is a functional block diagram of the present invention. The indicated gear position detection means +50 detects the indicated gear position Sx of the main transmission 14, that is, the actual gear position.

When the operation position of the sub-transmission 16 changes from H to L, the predetermined time Ta calculation means 152 calculates the intake throttle opening degree θ,
A predetermined time Ta is calculated based on the oil temperature T1, the vehicle speed v1, and the commanded gear position Sx. However, when the vehicle speed ■=0, that is, when the vehicle is stopped, the predetermined time Ta is set to zero regardless of other parameters. The timer 154 measures the elapsed time T1 since the change from H to L, and the comparing means 156 compares Ti and Ta. Solenoid valve control means 158° is T
The solenoid valve 102 for under-grabbing control is kept on until Ta reaches Ta, and the solenoid valve 102 for under-grabbing control is turned off after Ta has elapsed.

In addition, at time t1, which is the starting point of the predetermined time Ta in the ungrabbing control, the L-H position signal of the L-H position sensor 30 changes to + (mustard), so the position of the L-H switching valve 60 can actually be detected. It can be detected from the output of the sensor or from the fall of the servo oil pressure Pc detected by the oil pressure sensor 44.

In the embodiment, the solenoid valve 102 is provided in the discharge oil passage 100, but it may be of a type that limits the supply of oil to the low speed brake 26 by opening and closing the oil passage 86.

Although the present invention has been described in terms of embodiments, it will be apparent to those skilled in the art that various modifications to this embodiment may be made within the scope of the invention.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram of the present invention, Fig. 2 is an overall configuration diagram of the automatic transmission, Fig. 3 is a detailed diagram of the hydraulic control device shown in Fig. 2, and Fig. 4 is a sub-transmission while the vehicle is running. FIG. 5 is a diagram illustrating the characteristics of the predetermined time during which the solenoid valve is held open after switching the switching valve in the ungrab control. FIGS. 7 and 8 are diagrams illustrating the overlap control performed by the CPU when downshifting the auxiliary transmission while the vehicle is stopped. It is a flowchart. 14... Main transmission, 16... Sub-transmission, 24...
Clutch for high speed stage, 26... Brake for low speed stage, 48
...CPU 0 Patent applicant Toyota Motor Corporation Aisin Warner Co., Ltd. Figure 4 Time Figure 5 ↓'ILK
! Speed V Figure 6

Claims (1)

[Claims] 1. Hydraulic control of an automatic transmission having a main transmission having a plurality of gears and a sub-transmission connected in series with the main transmission and capable of switching between high and low gears by manual operation. In the device, when a manual operation is performed to change the gear stage of the auxiliary transmission from a high gear to a low gear, underlap control is performed on the friction engagement device of the auxiliary transmission while the vehicle is running, and the vehicle is stopped. 1. A hydraulic control device for an automatic transmission, characterized in that during a period, overlap control is performed on a friction engagement device of an auxiliary transmission. 2. The underlap control is performed by limiting the supply of hydraulic medium to the low-speed friction engagement device of the auxiliary transmission, and the overlap control is performed by limiting the supply of hydraulic medium to the low-speed friction engagement device of the auxiliary transmission. 2. The hydraulic control device according to claim 1, wherein the control is performed by discontinuing the restriction of the supply of hydraulic medium. 3. A solenoid valve is provided in the oil path that connects the oil path that leads the hydraulic medium to the low-speed frictional engagement device of the auxiliary transmission to the drain, and the underlap control and overlap control control the opening and closing of the solenoid valve. The hydraulic control device according to claim 2, characterized in that the hydraulic control device is operated by.