JPS61184260A - Hydraulic control apparatus of automatic transmission - Google Patents

Abstract

PURPOSE:To obviate the time-lag of engine brake in down-shift by carrying out symultaneous switch control in lieu of underlap control in down-shift when an intake throttle valve of a hydraulic control apparatus has a predetermined opening or less. CONSTITUTION:A down-shift detecting means 130 detects the down-shift through the detection of a shift valve and calculates 134 down-shift detecting time Ta from vehicle speed V, opening theta of an intake throttle and oil temperature T. The passage time Ti of a timer 132 is compared 136 with Ta to control a solenoid valve 78 for controlling underlap with a solenoid valve controlling means 138 and controllably open and close an oil path. Thus, the delay of effect of an engine brake is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic control device for an automatic transmission, and particularly to downshift control.

Conventional technologyIn an automatic transmission with a clutch-to-clutch split section (shift control performed by switching the hydraulic friction engagement device from one side to the other), when the accelerator pedal is depressed, the engine In order to increase the speed appropriately and alleviate the gear shift collision, the engagement timing of the low gear friction engagement device is delayed from the release timing of the high gear friction engagement device, and both friction engagement devices are maintained in the released state. Underlap control is required (for example, in Japanese Patent Application 1987-
No. 87760).

However, if underlap control is executed during a downshift, such as a manual shift from D (drive) range to 2 (second) range, which is performed when the intake throttle valve is fully open, that is, when the idle link is open, the time required until engine braking is applied is The delay becomes longer, and since the underlap period is the same as the automatic transmission's neutral station, the vehicle will run idly, which not only gives the driver a sense of anxiety, but also causes the engine rotation speed to drop to idling speed during the underlap period. descend to speed, then
When the low-speed frictional engagement device enters the locked state, the engine rotational speed rapidly increases compared to the idling rotational speed, so that the durability of the friction material of the low-speed frictional engagement device decreases.

Problems to be Solved by the Invention It is an object of the present invention to solve the problem in an automatic transmission that performs underlap control during a downshift, and to solve the problem of engine braking time delay and low speed at 5 of the downshift during a period when the intake throttle valve is almost at an idling opening. The objective is to eliminate problems caused by underlap control, such as a decrease in the durability of the friction material of the friction retaining device for the step □.

Means for Solving the Problems In order to achieve this object, the hydraulic control device for an automatic transmission of the present invention includes a first frictional engagement device that is held in an engaged state in a first gear stage, a first a second frictional engagement device that is held in an engaged state at a second gear that is one higher gear than the first gear; the first frictional engagement device is connected to a hydraulic medium supply oil path; A shift valve that connects each of the frictional engagement devices to a drain to switch from the second gear to the first gear; a solenoid valve that restricts the supply of hydraulic medium to the first frictional engagement device; A time measuring means for measuring the elapsed time from the time when the second gear position is switched to the first gear position, a vehicle speed sensor that detects the vehicle speed, a throttle opening sensor that detects the intake throttle opening, A time calculation means for calculating a predetermined time related to the vehicle speed and intake throttle opening, and when the intake throttle opening is equal to or greater than a predetermined value, the elapsed time measured by the time measurement means is the time calculated by the time calculation means. In addition, if the intake throttle opening is less than a predetermined value, the shift valve changes from the second gear position to the first gear position. and a solenoid valve control means for controlling the solenoid valve by an electric signal so that hydraulic medium is supplied to the first frictional engagement device immediately when the gear position is shifted to the first gear position.

Effect (A) In the case of a downshift during a period in which the intake throttle opening is greater than or equal to a predetermined value, that is, in the case of a downshift that occurs as the accelerator pedal is depressed: The shift valve shifts from the position corresponding to the second gear position. When the gear is shifted to a position corresponding to the first gear, the second frictional engagement device is connected to the drain, its oil pressure decreases, and finally the second frictional engagement device is released.

On the other hand, even after the valve is switched to shift 1, the first frictional engagement device restricts the supply of hydraulic medium by the electromagnetic valve for a predetermined time related to the vehicle speed, etc. After the device is released M, it remains in the released state, resulting in an underlap period.

Thus, during this underlap period, the engine revs up to a rotational speed that is related to the vehicle speed.

After a predetermined period of time has elapsed, the restriction on the supply of hydraulic medium to the first frictional engagement device by the electromagnetic valve is lifted, and the first frictional engagement device is supplied with the hydraulic medium and quickly enters the engaged state. 1 gear stage is generated.

(B) In the case of a downshift during a period in which the intake throttle valve is in an idling opening state and the opening is less than a predetermined opening: The first frictional engagement device Upon switching from the position to the first gear position, hydraulic medium is immediately supplied, and the first frictional engagement device becomes engaged at the same time as the second frictional engagement device becomes released.

Effects of the Invention As described above, according to the present invention, in a downshift when the intake throttle valve is less than a predetermined opening degree, simultaneous switching control is performed instead of underlap control.
Dry running of the vehicle and delay in application of the engine brake are avoided, thereby preventing IL from giving the driver a sense of anxiety. In addition, sudden fluctuations in the engine rotation speed, such as when the engine rotation speed decreases to the idling rotation speed and then suddenly rises above the idling rotation speed due to the engagement of the low-speed friction engagement device, are avoided. This prevents deterioration in the durability of the friction material of the low-speed friction engagement device.

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

In FIG. 2, an oil pump 10 sucks oil in an oil pan 12, pressurizes it, and discharges it. Other hydraulic control circuits 14 include a primary regulator valve and the like, and the primary regulator valve generates line pressure PA in the oil passage 16. 2-3 The shift valve 20 is a port connected to the line pressure oil line 16 as a supply pressure oil line.
−22, 24, drain 26, 28, and other ports 30132, and the ports and drains 22, 24, 26, 28° 3 are connected to the vehicle speed ■ and throttle opening 0.
Controls connections between 0.32 and 0.32. The third coupling clutch 34 is held engaged in the third gear and is connected to the port 30 via an oil passage 36.

The accumulator 38 is connected to oil w536, and the oil path 36
An orifice 40 and a reverse first stop valve 42 are provided in parallel with each other in the middle. The check valve 42° opens to allow oil in the third clutch 34 to flow toward the port 30. The second speed brake 44 is held in an engaged state in the second speed and is connected to the port 32 via an oil passage 46.

The accumulator 48 is connected to the oil passage 46, and an orifice 50 and a check valve 52 are provided in parallel with each other in the middle of the oil passage 46. The check valve 52 opens when the oil of the second continuous brake 44 flows toward the port 32. A drain oil passage 54 branches from the oil passage 46 between the port 32 and the orifice 50 and connects the oil passage 46 to a drain. The vehicle speed sensor 62 detects the vehicle speed V, the throttle opening sensor 64 detects the intake throttle opening θ, and the shift position sensor 66 detects D (drive) and R (reverse) selected by the driver. The pattern select switch 68 detects the driving pattern such as economy (economical driving) and power (output driving) selected by the driver, and the oil temperature sensor 70 detects the shift position of the oil pan 1.
Detect the temperature T of the oil in 2. The CPU 76 includes sensors or switches 62, 64, 66, . Solenoid valve 7 as a solenoid valve based on the input signal from 68.70
8 is controlled by electrical signals. The solenoid valve 78 connects to the solenoid 80 and, in relation to the solenoid 80, to the discharge oil passage 54.
It has a valve body 82 that opens and closes.

The control performed by the CPU 76 during the downshift that occurs when the accelerator pedal is first depressed will be described with reference to FIG. In FIG. 3, Pc is the servo oil pressure of the third clutch 34, and Pb is the servo oil pressure of the second brake 44.

Before time t1, the 2-3 shift 1 valve 20 is held at the high speed stage side, the boat 30 is connected to the boat 22, and the boat 32 is connected to the drain 28. As a result, the third coupling clutch 34 is supplied with the line pressure Pl from the line pressure oil passage 16 and is held in the engaged state, and also,
Since the oil in the second brake 44 has been drained from the drain 28 and the second brake 44 is held before the release 'M station, the automatic transmission is in the third speed state.

At time t1, the 2-3 shift valve 20 is switched from a high speed position to a low speed position. This switching is
2-3 Depending on the relationship between the throttle pressure (corresponding to the intake throttle opening) and the governor pressure (corresponding to the vehicle speed) acting on the spool of the shift valve 20, or 2-3
This is carried out by controlling the control pressure acting on the spool of the shift valve 20 using a solenoid valve (not shown). Due to this switching, the port 30 is connected to the drain 26 and the port 32 is connected to the boat 24, so that the servo oil pressure Pc starts to decrease from time t1. Even after the 2-3 shift valve 20 is switched, the solenoid valve 78 keeps the discharge oil passage 54 open for a predetermined time Ta, so that the port 32
Although the line pressure Pl of the line pressure oil passage 16 is guided, the servo oil pressure Pb is maintained at zero, and the engagement of the second speed brake 44 is prevented.

At time t2 when a predetermined time TafJS has elapsed from time tl, the solenoid valve 78 closes the discharge oil passage 54. As a result, the servo oil pressure pb increases from time t2,
At time t3, after time Tb has elapsed from time t2, a predetermined oil pressure is reached, and the second speed brake 44 is in a semi-engaged state.

The period from when the servo oil pressure Pc appropriately decreases until time t3 is an underlap period in which both the third operation clutch 34 and the second combination brake 44 are in a released state, so that the engine can smoothly rev up.

FIG. 4 shows the characteristics of the predetermined time Ta.

As the vehicle speed V increases, the amount of engine rev required for downshifting increases, so the predetermined time Ta for lengthening the underlap period also increases. Further, as the throttle opening degree θ is lower (θ1<θ2), the speed at which the engine is revved up becomes lower, so the predetermined time Ta increases. If the solenoid valve 78 becomes closed after a time shorter than the predetermined time Ta defined in FIG. The engine revs up excessively, and in both cases, gear shift friction increases. Further, as the oil temperature T increases, the viscosity of the oil decreases, and the oil supply speed to the second speed brake 44 increases, so the predetermined time Ta increases as the oil temperature T increases. can be set to a value to compensate for deviations in the underlap period due to oil temperature T.

Next, the downshift control performed by the CPU 76 when a manual shift from D (drive) to 2 (second) is performed while the intake throttle valve is at the idling opening will be explained with reference to FIG. . Similarly to FIG. 3, Pc and Pb represent the servo oil pressures of the clutch 34 and brake 44, respectively.

Before time t11, the 2-3 shift valve 20 is held at the high speed position, the port 30 is connected to the port 22, and the boat 32 is connected to the drain 28. As a result, the third coupling clutch 34 is supplied with the line pressure Pl from the line pressure oil passage 16 and is held in the engaged state, and
Since the oil in the second combination brake 44 is drained from the drain 28 and the second combination brake 44 is held in the released state, the automatic transmission is in the third speed state.

At time tll, the 2-3 shift valve 20 is switched from a high speed position to a low speed position. The switching of the 2-3 shift valve 20 from the high speed side position to the low speed side position due to a manual shift from the D range to the 2nd range is in the case of a downshift from the 3rd speed to the 2nd speed in the D range. As shown in the figure, the control pressure acting on the spool of the 2-3 shift valve 20 is controlled by the relationship between the throttle pressure and the governor pressure acting on the spool of the 2-3 shift valve 20, or the control pressure acting on the spool of the 2-3 shift valve 20 is controlled by a solenoid valve (not shown). Furthermore, in the case of two ranges, this can be done by applying line pressure supplied from a manual valve (not shown) to the spool of the 2-3 shift valve as a control pressure. With this switching, port 30 goes to drain 26, port 32 goes to port 24,
Since they are connected, the servo oil pressure Pc is at the time tll.
It goes down from there. The solenoid valve 78 closes the discharge oil passage 54 immediately after the 2-3 shift valve 20 is switched when the throttle valve is idling, so the port 3
The line pressure PA of the second line pressure oil passage 16 is guided, and the servo oil pressure Pb of the second continuous brake 44 starts to rise immediately from time t11.

At time t12, the servo oil pressure Pb of the second continuous brake 44 reaches a predetermined value, and the second speed brake starts to be engaged. In this way, an underlap in which both the third clutch 34 and the second brake 44 are released is avoided.

FIG. 6 is a flowchart of a speed change control routine according to the control explained in FIGS. 3 and 5.

A flag F1 indicating that a downshift from third speed to second speed has occurred and a timer for measuring elapsed time (defined as time measured by this timer T1) are reset as initialization. (Step 90.92). In the main routine (step 94), an instructed gear position is calculated based on the vehicle speed V and the intake throttle opening θ, and based on this instructed gear position, the drive control of the solenoid valve for gear position control (
(on/off control) is performed (step 96), and each shift valve is placed in a position corresponding to the designated gear position. If there is no downshift from 3rd gear to 2nd gear, (the determination in step 98 is p=Q, the determination in step 100 is N0
8), the main routine (step 94) is executed again, but if there is a downshift from 3rd gear to 2nd gear (YES in step 100), flag F is set (step 102L). The timer starts measuring the elapsed time (step 104).Next, the vehicle speed v1 oil temperature T1 and intake throttle opening θ are read (steps 106, 108, 110), and the intake throttle opening θ is set to IDL (idling opening). degree) (determination at step +12 is NO), the predetermined time Ta is V, T, 1
3 (step 114), and compares the timer measurement time T1 with the predetermined time Ta (step 116).
), if Ti<Ta, that is, after the 2-3 shift valve 20 is switched from the high speed position to the low speed position, Ta
The underlap control solenoid valve 7
8 is turned on (step 118), the discharge oil passage 54 is opened, and if Ti≧Ta, that is, after Ta has elapsed, the underlap control solenoid valve 78 is turned off (step +20), and the discharge oil path 54 is opened. Close oil passage 54 and reset flag F and timer (step 122.12
4). If the intake throttle opening θ is IDC (YES in step 112), by setting Ta to zero for the predetermined time (step +13), T1≧Ta is guaranteed (T1≧Ta in step 116), The underlap control solenoid valve 78 is turned off (step +
20), reset the flag and timer T1 (steps 122 and 124).

FIG. 1 is a functional block diagram of the present invention. 3rd gear → 2nd gear
The downshift detection means 130 detects a change in the gear position indicated by the CPU 76, a change in the servo oil pressure Pc, or a change in the position of the 2-3 shift valve 20.
A downshift from speed to second speed is detected, and timer 132 measures elapsed time T1 from this detection time. Ta calculation means 134 calculates a predetermined time Ta from the vehicle speed v1, intake throttle opening degree 01, and oil WET at the detection time of downshift from third speed to second speed.

However, in the case of Q: IDL (idling opening), Ta=
It is 0. The comparison means +36 compares T+ and Ta, and the solenoid valve control means 138 turns on the underlap control solenoid valve 78 to open the discharge oil passage 54 during the period T1<Ta, and performs the underlap control when T1>Ta. The solenoid valve 78 is turned off to close the discharge oil passage 54.

In the embodiment, the solenoid valve 78 is provided in the discharge oil passage 54, but it may be of a type that limits the supply of oil to the second continuous brake 44 by opening and closing the oil passage 46. It goes without saying that the present invention can be applied not only to downshifting from third speed to second speed, but also to control related to other downshifts.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram of the present invention, FIG. 2 is a configuration diagram of an embodiment of the present invention, and FIG. 3 is control performed by CPH in the case of a downshift that occurs as the accelerator pedal is depressed. Fig. 4 is a diagram showing the characteristics of the predetermined time period during which the solenoid valve is held open after the shift valve is switched, and Fig. 5 is a diagram showing the characteristics of the predetermined time period during which the solenoid valve is held open after switching the shift valve. C in case of shift
FIG. 6, which is a diagram explaining the control executed by the PLL, is a flowchart of a speed change control routine according to the control shown in FIGS. 3 and 5. 16...Line pressure oil passage, 20...2-3 shift valve, 26...Drain, 34...3rd speed clutch,
44...Second continuous brake, 62...Vehicle speed sensor,
64... Throttle opening sensor, 76... CPU,
78... Solenoid valve, 134... Ta time calculation means, 138... Solenoid valve control means.

Claims (1)

[Claims] 1. A first frictional engagement device that is held in an engaged state in a first gear position, and an engaged state in a second gear position that is one higher gear position than the first gear position. a second frictional engagement device held in a shift valve for switching to the first gear position; a solenoid valve for restricting the supply of hydraulic medium to the first frictional engagement device; when the shift valve is switched from the second gear position to the first gear position; , a time measuring means for measuring elapsed time, a vehicle speed sensor for detecting the vehicle speed, a throttle opening sensor for detecting the intake throttle opening, a time calculating means for calculating a predetermined time related to the vehicle speed and the intake throttle opening, and an intake throttle opening. When the throttle opening is equal to or greater than a predetermined value, the supply of hydraulic medium to the first frictional engagement device is restricted until the elapsed time measured by the time measuring means reaches the time calculated by the time calculating means. Also, if the intake throttle opening is less than a predetermined value, the shift valve will shift to the second position.
an electromagnetic valve control means for controlling the electromagnetic valve by an electric signal so that hydraulic medium is supplied to the first frictional engagement device immediately when the gear position is changed from the gear position to the first gear position. A hydraulic control device for an automatic transmission, which is characterized by: 2. When the intake throttle opening is less than the predetermined value,
The hydraulic control device according to claim 1, characterized in that the intake throttle valve is at an idling opening. 3. The hydraulic control device according to claim 1, wherein the time calculated by the time calculation means is zero when the intake throttle opening is less than a predetermined value. 4. The electromagnetic valve according to claim 1, wherein the solenoid valve is a valve that opens and closes an oil passage connecting an oil passage for hydraulic medium from the shift valve to the first frictional engagement device to a drain. Hydraulic control device.