JPH0581793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention provides a first gear stage that is achieved by engagement of first and second hydraulically actuated friction elements;
Occurs when shifting from the first gear to the second gear in an automatic transmission equipped with a gear transmission mechanism in which the second gear is achieved by the engagement of a friction element and the locking function of a one-way clutch. The present invention relates to a hydraulic control device for an automatic transmission that can reduce shift shocks.

[Conventional technology]

Automatic transmissions for vehicles connect arbitrary rotating elements in the gear transmission mechanism to the input shaft or to the transmission casing by selectively supplying and discharging hydraulic pressure to friction elements such as clutches and brakes. The gear ratio is fixed and the gear ratio is automatically switched depending on the driving condition of the vehicle. Such a transmission is required to have a small shock during gear shifting in order to protect equipment, equipment, etc. and maintain a comfortable ride.

An example of an automatic transmission for a vehicle will be explained using FIGS. 4 and 5, which are also drawings showing an embodiment of the present invention. The crankshaft 12 of the engine 11 that serves as the power source of the vehicle is connected to the pump 1 of the torque converter 13.
4 is integrally connected. The torque converter 13 is composed of a stator 16 connected to a case 18 via the pump 14, turbine 15, and one-way clutch 17, and the stator 16 is moved in the same direction as the crankshaft 12 by the action of the one-way clutch 17. The structure allows rotation in the opposite direction, but does not allow rotation in the opposite direction. The torque transmitted to the turbine 15 is transmitted by an input shaft 19 to a gear transmission mechanism disposed at the rear thereof that achieves four forward speeds and one reverse speed.

The gear transmission mechanism includes three sets of clutches 20, 21,
22, two sets of brakes 23 and 24, one set of one-way clutch 25, and one set of Ravigneau type planetary gear mechanism 26. The same planetary gear mechanism 26
is ring gear 27, long pinion gear 28,
Short pinion gear 29, front sun gear 3
0, rear sun gear 31, both pinion gears 28, 2
The ring gear 27 is connected to the output shaft 33, and the front sun gear 30 is connected to the kickdown drum 34 and the front clutch 2.
The rear sun gear 31 is connected to the input shaft 19 via a rear clutch 21, and the carrier 32 is connected to the case via a low reverse brake 24 and a one-way clutch 25, which are arranged in parallel. 18 and is also connected to an input shaft 19 via a four-speed clutch 22 disposed at the rear end of this gear transmission mechanism. The kickdown drum 34 can be integrally connected to the case 18 by the kickdown brake 23, and the torque passing through the planetary gear mechanism 26 is transmitted from an output gear 35 fixed to the output shaft 33 to a drive (not shown). It is transmitted to the drive wheels via the shaft.

Each of the clutches 20 to 22 and the brakes 23, 24, which are friction elements, is constituted by a hydraulic device equipped with an engaging piston device or a servo device.
It is selectively operated via a hydraulic control device by pressure oil generated by an oil pump (not shown) connected to the.

The second gear of the gear transmission mechanism with the above configuration is constructed by releasing the front clutch 20, 4th gear clutch 22, and low reverse brake 24, and engaging the rear clutch 21 and kickdown brake 23. The gear position is achieved by engaging the rear clutch 21 and fixing the carrier 32 by the locking function of the one-way clutch 25. Therefore, shifting from the second speed to the first speed without operating the select lever to the first speed fixed range is achieved only by releasing the kick down brake 23. In this case, the kick down brake 23 Knock down drum 34 by releasing
The rotation of the carrier 32, which becomes capable of free rotation, begins to decrease, and at the point when the carrier 32 is about to rotate in the opposite direction, the one-way clutch 25 functions to fix the carrier 32, and the first gear is achieved. .

A part of the hydraulic control device that achieves the above-mentioned speed change is installed in the fifth
As shown in the figure. A 1-2 shift valve 37 is connected to a kick-down servo 36 that controls the operation of the kick-down brake 23 through an oil passage 38.
A hydraulic control valve 39 and a shift control valve 40 are communicated with the 2-shift valve 37 via oil passages 41 and 42, respectively. The hydraulic control valve 39 is pressurized oil (line pressure) supplied to the oil passage 50 from a hydraulic source (not shown).
is adjusted to a desired oil pressure value according to the control oil pressure in the oil passage 51 and supplied to the oil passage 41. The control oil pressure in the oil passage 51 is controlled by a solenoid valve whose duty is controlled by an electronic control device 54. 55, the discharge is appropriately controlled and adjusted to a desired pressure. The shift control valve 40 is controlled by a pair of solenoid valves 43 and 44 whose excitation state combinations are switched and controlled by the electronic control device 54.
are controlled to be switched to positions corresponding to each gear stage from first speed to fourth speed.

When the second gear is achieved in the hydraulic control device with the above configuration, the solenoid valve 43 is demagnetized to close the oil passage 45, and the solenoid valve 44 is energized to open the oil passage 46 and enter the oil passage 46. Since the hydraulic pressure of
The line pressure from the oil passage 48 is supplied to the same 1.
The spool 49 of the -2 shift valve 37 is located at the right end in FIG. 5, so that the oil passage 41 and the oil passage 38 are in communication with each other. On the other hand, when the gear position is achieved, the operation of the solenoid valve 55 is stopped, the control oil pressure in the oil passage 51 reaches the highest pressure, and the line pressure from the oil passage 50 is not reduced but flows to the oil passage 41. Since this line pressure is supplied to kickdown servo 3,
6, the piston 53 is displaced to the left in FIG. 5, and the kick-down brake 23 is in a state in which the kick-down drum 34 is tightened.

When shifting from this state to 1st gear other than by operating the select lever to the 1st gear fixed range, the electronic control unit 54 issues a shift signal to 1st gear depending on the driving condition of the vehicle and switches both solenoid valves. 43 and 44 to discharge the oil pressure in the oil passages 45 and 46, the spool 47 is moved to the left end as shown in FIG.
Ejected from EX. As a result, the spool 49 of the 1-2 shift valve 37 is moved to the left end position shown in FIG.
The hydraulic pressure is suddenly discharged, the piston 53 is moved to the right in FIG. 5 by the compression coil spring 56, the engagement of the kick-down brake 23 with the kick-down drum 34 is released, and the first speed is achieved. become.

In this case, the solenoid valve 55
Control is performed to discharge the control hydraulic pressure in the oil passage 51 with the duty rate of 100% (maintained in the open state), and to discharge the hydraulic pressure in the oil passage 41.
This is to prevent high line pressure from being supplied to other oil passages connected to the shift valve 37.

The more detailed structure and operation of the above conventional technology are as follows:
As disclosed in Japanese Patent Application Laid-Open No. 58-46258, etc.,
The explanation here will be omitted.

[Problem that the invention seeks to solve]

In shifting from second speed to first speed in the conventional configuration, when the electronic control unit 54 issues a speed change signal, the spool 49 of the 1-2 shift valve 37 is immediately moved to the first speed side, and the kick-down servo 36 is moved to the first speed side. The hydraulic pressure is suddenly discharged, and the down brake 23
is released rapidly. As a result, Figure 2c
As shown by the chain line in FIG.
At the end of the shift where the gear is fixed, a large torque fluctuation occurs, which rapidly increases to a large torque corresponding to the first speed, resulting in an extremely large shift shock.

The present invention provides the first and second
An automatic transmission equipped with a gear transmission mechanism in which a first gear is achieved by engagement of the friction element, and a second gear is achieved by engagement of the first friction element and a locking function of a one-way clutch. An object of the present invention is to provide a hydraulic control device for an automatic transmission that can reduce the shift shock that occurs when shifting from the first gear to the second gear.

[Means for Solving the Problems] In the hydraulic control device for an automatic transmission according to the present invention, a first gear stage is achieved by engagement of hydraulically actuated first and second friction elements, and the above-mentioned first friction A gear transmission mechanism in which a second gear stage is achieved by engagement of the elements and a locking function of a one-way clutch, a shift valve that switches the supply and discharge of hydraulic pressure to the second friction element, and a control of the hydraulic pressure to the second friction element. an electronic control means for controlling the hydraulic pressure by controlling switching of the shift valve and emitting a signal to the electrohydraulic control means; detecting the rotational speed of a rotating element of the gear transmission mechanism; In an automatic transmission equipped with a speed detection means for supplying an electric signal corresponding to the same rotational speed to the electronic control means, when shifting from the first gear to the second gear, the electronic control means: An effective shift in which the shift valve is held in a position where hydraulic pressure is supplied to the second friction element until the shift is completed, and the rotational speed of the rotary element deviates from the rotational speed corresponding to the first gear. and the end point of the effective shift at which the rotational speed of the rotary element matches the rotational speed corresponding to the second gear, and the effective shift is completed before the start of the effective shift, during the effective shift, or at the end of the effective shift. The present invention is characterized in that the oil pressure applied to the second friction element is controlled in accordance with the speed change state in each subsequent period.

[Effect]

Since the hydraulic control device for an automatic transmission according to the present invention is configured as described above, it controls the hydraulic pressure to the second friction element to be released when shifting from the first gear to the second gear. This makes it possible to maintain torque transmission during gear shifting with the second friction element, making it possible to gently and lessen torque fluctuations of the output shaft during gear shifting, thereby reducing gear shifting shock.

〔Example〕

A first embodiment of the hydraulic control device according to the present invention
This will be explained in detail with reference to FIGS. 4 and 5.

In one embodiment of the present invention, in addition to the conventional structure described above, a rotational speed detection device 60 for detecting the rotational speed of the kickdown drum 34 and a rotational speed of the output shaft 33 are used to detect the vehicle running speed. A vehicle speed detection device 61 is provided to detect the
Signals from both detection devices 60 and 61 are input to the electronic control device 54.

Next, a control mode when shifting from second speed to first speed in the above configuration will be explained according to the flowchart shown in FIG.

When the conventionally known select lever is not moved to the first gear fixed position, a shift command from the second gear to the first gear is issued from the electronic control unit 54 according to the driving state of the vehicle using the same control method as the conventional one. When activated, the duty rate of the solenoid valve 55 is increased with respect to time at a predetermined inclination angle α, that is, at a predetermined rate of change, while maintaining the 1-2 shift valve 37 at the second speed position. That is, by lowering the control oil pressure in the oil passage 51, the kick-down servo 36 is transferred from the oil passage 41 to the 1-2 shift valve 37 and the oil passage 38.
The line pressure supplied to the pump is reduced at a predetermined rate of change. As the line pressure gradually decreases, the engagement of the kick-down brake 23 with the kick-down drum 34 is gradually released, and the kick-down drum 34 finally begins to rotate (i.e., from the rotational speed corresponding to the second speed = 0 rpm). shift) effective gear shifting is initiated. When the rotation speed detection device 60 detects the start of rotation of the kick-down drum 34, that is, the start of the effective speed change,
The duty rate of the solenoid valve 55 at the start of the effective shift is maintained until the kickdown drum 34 reaches a rotational speed corresponding to the first speed, and the oil pressure to the kickdown servo 36 during the shift is maintained.

This control makes it possible to moderate the decrease in the torque of the output shaft 33 immediately after the start of the shift, and to maintain the torque transmission during the shift with the kick-down brake 23, thereby making it possible to reduce the decrease in the torque of the output shaft 33.

Next, the vehicle speed detecting device 6 at the time of starting the shift
The kick-down drum 3
When the rotational speed reaches No. 4, that is, when the end of the effective shift is detected, the duty rate of the solenoid valve 55 is increased again, and the oil pressure to the kickdown servo 36 is decreased. In this case, the rate of increase in the duty rate (rate of decrease in oil pressure) is determined by adjusting the difference between the constant duty rate during the effective shift and the predetermined duty rate in the predetermined time so that the duty rate can reach the predetermined duty rate within the predetermined time. The divided value shall be the value.

By executing this control, the hydraulic pressure in the kick-down servo 36 is gradually discharged, the holding of the transmitted torque by the kick-down brake 23 is gradually reduced, and the transmission torque is gradually shifted to being held by the one-way clutch 25. Therefore, the increase in the output shaft torque at the end of the shift can be slowed down.

Then, when the predetermined time has elapsed from the end of the effective shift, the duty rate of the solenoid valve 55 is set to 100% to completely discharge the hydraulic pressure in the kick-down servo 36, and finally both solenoid valves of the shift control valve 40 are By energizing the valves 43 and 44 and setting the spool 47 to the first speed position shown in FIG. 5, the 1-2 shift valve 37 is moved to the first speed position and the shift is completed.

As mentioned above, if the oil pressure to the kick-down servo 36 is controlled while the 1-2 shift valve 37 is held on the second speed side when shifting from the second speed to the first speed,
As the kick-down brake 23 is gradually released and the holding of the transmitted torque is smoothly transferred from the kick-down brake 23 to the one-way clutch 25, a sudden drop in output shaft torque at the beginning of a shift, a drop during a shift, and a shift are avoided. The sudden increase in the final stage can be reduced, and as shown by the solid line in FIG. 2c, the fluctuation width of the output shaft torque can be reduced, and the rate of change of torque fluctuation can also be made gentler, making it possible to reduce the shift shock.

The solid lines shown in FIGS. 2a and 2b represent the change characteristics of the rotational speed of the kickdown drum 34 and the duty rate of the solenoid valve 55 with respect to time during the shift period.

Next, a modification of the above embodiment will be explained with reference to FIG. 3. In this modification, instead of the control of maintaining the duty rate during the effective shift in the above embodiment at the duty rate at the start of the effective shift, , detects the rotational speed of the duty rate (i.e., the oil pressure to the kickdown servo 36) during the effective gearshift so that the rate of change in the rotational speed of the kickdown drum 34 during the effective gearshift becomes a predetermined change rate set in advance. Feedback control is performed in response to a signal from the device 60,
In addition, the control for increasing the duty rate at a predetermined speed for a predetermined time after the end of the effective shift is omitted, and the duty ratio is set to 100% immediately after the end of the effective shift, and the oil pressure of the kick-down servo 36 is discharged. .

According to the above modification, by executing the feedback control, the decrease in output shaft torque during gear shifting can be further reduced than in the above embodiment. Therefore, even if the duty rate of the solenoid valve 55 is set to 100% immediately after the end of the effective shift and the oil pressure of the kick-down servo 36 is rapidly discharged, the rate of change in torque fluctuation will be rapid, but overall it is better than the conventional one. Since the width of the torque fluctuation is small, it is possible to reduce the occurrence of shift shock at the end of the shift. (See the broken lines in Fig. 2 b and c.) As is clear from the above points of view, if the above embodiment and the modification are combined, the duty rate feedback control can be performed as in the modification during effective gear shifting. If control is performed such that the duty rate is increased at a predetermined speed for a predetermined period of time after the end of the effective shift, the range of torque fluctuation of the output shaft 33 can be made extremely small, and the rate of change of torque fluctuation can be made gentler. This can be significantly reduced.

It should be noted that the above embodiments and modifications are the second embodiment of the present invention.
Although the case where the present invention is applied to the control of a downshift from 1st gear to 1st gear is shown, the gear before shifting is achieved by a hydraulically actuated friction element, and the gear after shifting is achieved by a one-way clutch lock. It can be applied to any type of speed change as long as it is a speed change between gears that can be achieved by the function.

Furthermore, in the above embodiments and modifications, the rotational speed of the kick-down drum 34 is detected in order to detect the start and end of effective gear shifting, but the rotational speed of the input shaft 19 may also be detected. , the rotational speed of the engine 11 may be detected assuming that it is rotating at substantially the same speed as the input shaft 19.

〔Effect of the invention〕

According to the present invention, the first gear is achieved by the engagement of the first and second hydraulically actuated friction elements, and the second gear is achieved by the engagement of the first friction elements and the locking function of the one-way clutch. In an automatic transmission equipped with a gear transmission mechanism in which gears are achieved, the first
When shifting from a gear to a second gear, the shift valve is held at a position where hydraulic pressure is supplied to the second friction element until the gear shift is completed, and during this time, the electronic control unit controls the second friction element. Since the second friction element is gradually released by controlling the hydraulic pressure to the gearbox, the drop in output shaft torque during gear shifting is suppressed, the fluctuation range of the torque becomes smaller, and gear shifting shock is reduced. .

Further, since the sudden occurrence of the torque fluctuation can be suppressed, the shift shock can be further reduced.

Furthermore, the rotational speed of the rotating element of the gear transmission mechanism is detected to detect the start and end of the effective shift during the shift, and before the effective shift,
During each period during effective shifting and after the end of effective shifting,
Since the hydraulic pressure to the second friction element is controlled according to the gear shift state, compared to conventional transmissions in which the hydraulic pressure to the open side friction element is simply discharged via an orifice or an accumulator, etc. , regardless of changes in the time until the actual shift starts due to deterioration of the transmission oil, changes in the transmission over time, or changes in oil temperature, it is possible to always perform more appropriate hydraulic control according to the shift state, and the shift speed can be improved. This can further reduce shock.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the control contents of an apparatus according to an embodiment of the present invention, and FIGS. 2a, b, and c show the rotational speed of the kickdown drum 34 with respect to time in the above embodiment and the modification shown in FIG. A graph showing the change characteristics of duty ratio and output shaft torque, FIG. 3 is a flowchart showing a modification of the control content shown in FIG. 1, and FIG. 4 is a mechanism showing the structure of an automatic transmission to which the present invention is applied. The conceptual diagram and FIG. 5 are hydraulic circuit diagrams showing the main parts of the hydraulic control device. 11...Engine, 12...Crankshaft, 21
... Rear clutch, 23 ... Kick down brake, 25 ... One-way clutch, 26 ... Ravigneaux type planetary gear mechanism, 32 ... Carrier, 33 ...
...Output shaft, 34...Kickdown drum, 36...
... Kickdown servo, 37 ... 1-2 shift valve, 39 ... Hydraulic control valve, 40 ... Shift control valve, 54 ... Electronic control device, 55 ... Solenoid valve, 6
0... Rotation speed detection device, 61... Vehicle speed detection device.

Claims (1)

[Scope of Claims] 1. A first gear is achieved by the engagement of hydraulically operated first and second friction elements, and a second gear is achieved by the engagement of the first friction elements and the locking function of the one-way clutch. A gear transmission mechanism that achieves the gear shift, a shift valve that switches the supply and discharge of hydraulic pressure to the second friction element, an electro-hydraulic control means that can control the hydraulic pressure to the second friction element, and a switching control of the shift valve. and an electronic control means for controlling the hydraulic pressure by emitting a signal to the electro-hydraulic control means, detecting the rotational speed of the rotating element of the gear transmission mechanism, and supplying an electric signal corresponding to the rotational speed to the electronic control means. In the automatic transmission equipped with a speed detection means, when shifting from the first gear to the second gear, the electronic control means controls the shift valve to the second friction element until the shift is completed. and the rotational speed of the rotating element is maintained at a position where hydraulic pressure is supplied to the rotating element, and the rotational speed of the rotating element is at the start point of an effective shift at which the rotational speed of the rotating element deviates from the rotational speed corresponding to the first gear, and the rotational speed of the rotating element is at the position corresponding to the second gear. detecting the end point of the effective shift that corresponds to the rotational speed corresponding to the gear position, and changing the hydraulic pressure to the second friction element in each period before the start of the effective shift, during the effective shift, and after the end of the effective shift; A hydraulic control device for an automatic transmission characterized by controlling according to the state. 2. The hydraulic control device for an automatic transmission according to claim 1, wherein the hydraulic pressure is reduced at a predetermined rate of change during the effective shift start period. 3. The hydraulic control device for an automatic transmission according to claim 2, wherein the hydraulic pressure at the start of the effective shift is maintained during the effective shift. 4. A patent claim characterized in that, during the effective gear shift, the oil pressure is feedback-controlled in response to a signal from the speed detection means so that the rate of change in the rotational speed of the rotating element becomes a preset rate of change. A hydraulic control device for an automatic transmission according to item 2. 5. The hydraulic control device for an automatic transmission according to claim 3 or 4, wherein the hydraulic pressure is reduced at a predetermined rate of change after the end of the effective shift. 6. Claim 3, characterized in that the oil pressure is reduced at a predetermined rate of change for a predetermined period of time from the end of the effective shift, and after the elapse of the predetermined time, the oil pressure is discharged to 0 kg/cm ² . Section or 4th
Hydraulic control device for automatic transmission as described in 2. 7 Immediately after completing the above effective gear shift, reduce the above oil pressure to 0.
A hydraulic control device for an automatic transmission according to claim 3 or 4, characterized in that the oil pressure is discharged at a rate of Kg/cm ² . 8. Claim 6 or 7, characterized in that the shift valve is switched to a position for discharging the hydraulic pressure from the second friction element at the same time or immediately after the hydraulic pressure is set to 0 kg/cm ² A hydraulic control device for an automatic transmission described in .