JPS62101952A - Speed change controlling method for automatic transmission gear of vehicle - Google Patents

Abstract

PURPOSE:To enable speed change to be carried out smoothly by gradually increasing oil pressure which is supplied to a friction engaging element, from a value set in accordance with the opening of a throttle valve when a transmission gear is shifted from a high-speed step to a low-speed step. CONSTITUTION:Down-shift lines by which speed change from a high speed step to a low speed step is executed when a vehicle is decelerated are set in an electronic controller 54. By means of such lines, solenoid valves 43, 44 and 45 can be controlled during the speed change from the high speed step to the low speed step in such a way that oil pressure supplied to a friction engaging element is increased gradually from a level preset in accordance with the opening of a throttle valve. Accordingly, a speed change with a small opening of a throttle valve, from a high speed step during low speed decelerating running to a low speed step can be carried out smoothly without causing any shock due to the speed change.

Description

[Detailed Description of the Invention] Field of Use in Motor Vehicles> The present invention provides a vehicle that achieves a shift from a high gear to a low gear without causing an excessive shift shock when the vehicle is decelerating at a low speed. The present invention relates to a speed change control method in an automatic transmission.

<Prior Art> An automatic transmission for a vehicle automatically switches the gear ratio according to the driving condition of the vehicle.

Such transmissions are required to have small shocks when changing gears in order to protect equipment, equipment, etc. and maintain a comfortable ride. Transmissions that electronically control the oil pressure supplied to engagement elements have already been put into practical use.

An example of an automatic transmission for a vehicle will be explained using FIGS. 5 and 6, which are also drawings showing an embodiment of the present invention. A crankshaft 12 of an engine 11 serving as a power source for the vehicle is integrally connected to a bond 14 of a torque converter 13. The torque converter 13 is connected to the case 1 via the bond 14, the turbine 15 and the one-way clutch l7.
The stator 16 is configured to rotate in the same direction as the crankshaft 12 due to the action of the one-way clutch 17, but is not allowed to rotate in the opposite direction. . turbine 15
The torque transmitted to the input shaft 19 is transmitted to a gear transmission mechanism disposed at the rear of the input shaft 19 that achieves four forward speeds and one reverse speed.

The gear transmission mechanism consists of three sets of clutches 20, 21, 22 and 2.
A set of brakes 23.24 and a set of one-way clutch 2
5 and one set of Ravigneau type planetary gear mechanism 26. The planetary gear mechanism 26 includes a cylinder gear 27, a long pinion gear 28, a short pinion gear 29, a front sun gear 30, a rear sun gear 31°, both pinion gears 2
The cylinder gear 27 is connected to the output shaft 33, and the front sun gear 30 is connected to the input shaft 1 via the kickdown drum 34 and the front clutch 20.
9, the rear sun gear 31 is connected to the input shaft 19 via the rear clutch 21, and the carrier 32 is connected to the case 18 via a low reverse brake 24 and a one-way clutch 25 that are arranged in parallel with each other. A four-speed clutch 22 is also provided at the rear end of this gear transmission mechanism.
It is connected to the input shaft 19 via. 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 shaft (not shown). is transmitted to the drive wheels via the

Each of the above-mentioned clutches 20 to 22 and brakes 23 and 24, which are frictional engagement devices, each comprises a hydraulic device equipped with an engagement piston device or a servo device, etc., and is connected to the pump 14 of the torque converter 13. It is selectively operated via a hydraulic control device by pressure oil generated by an oil pump (not shown).

The second speed of the gear transmission mechanism with the above configuration is achieved by releasing the front clutch 2, the 14th speed clutch 22 and the low reverse brake 24, and engaging the rear clutch 21 and kickdown brake 23. 3
The shift stage is achieved by releasing the 4th speed clutch 22, kickdown brake 23 and low reverse brake 24, and engaging the front clutch 20 and rear clutch 21. That is, the shift from the third speed to the second speed without operating the select lever to the second speed fixed range is achieved by releasing the front clutch 20 and engaging the kickdown brake 23. Therefore, in order to smoothly shift from the high speed 3rd speed to the low speed 2nd speed without causing a shock, it is necessary to control the degree of increase in the oil pressure supplied to the kickdown brake 23. involved in something.

FIG. 6 shows a part of the hydraulic control device that achieves the above-mentioned speed change by electronic control.

An l-2 shift valve 37 is communicated with an engagement-side hydraulic chamber 36L of the kick-down brake 23, which controls the operation of the kick-down brake 23, via an oil passage 38. The valve 39 and the shift control valve 40 are communicated with each other via oil passages 41j42. The oil pressure control valve 39 adjusts pressure oil (line pressure) supplied from a hydraulic source (not shown) to the oil passage 50 to a desired oil pressure value according to the control oil pressure in the oil passage 51, and supplies the adjusted oil pressure to the oil passage 41. In other words, the controlled oil pressure in the oil passage 51 is appropriately discharge-controlled by a solenoid valve 55 which is duty-controlled by an electronic control device 54, and adjusted to a desired pressure. Further, the shift control valve 40 is controlled by a pair of solenoid valves 43 and 44 whose combinations of excitation states are switched and controlled by the electronic control device 54, so that the central spool 47 is controlled at each gear stage from the first speed to the fourth speed. The switch is controlled to the position corresponding to the position.

Further, the hydraulic chamber of the front clutch 20 and the release side hydraulic chamber 36b of the kickdown servo 36 are communicated via an oil passage 59, and a 2-3 shift valve 70 is connected to the oil passage 59.
are communicated via an oil passage 62. The 2-3 shift valve 70 is communicated with the l-2 shift valve 37 via an oil passage 64 and also communicated with the shift control valve 40 via an oil passage 67.

In the coupled state of the third gear in the hydraulic control device having the above configuration, both the solenoid valves 43 and 44 are demagnetized and close the discharge oil passages 45 and 46, so that the spool 47 is connected to the oil passage 42 and the oil l-2 shift valve 37 and 2 via line 67
-3 Move to a state where line pressure is supplied to the shift valve 70. As a result, the oil passage 41 communicates with the oil passages 38 and 64 via the 1-2 shift valve 37, and the oil passage 64 communicates with the oil passage 62 via the 2-3 shift valve 70.

Here, when the gear stage is achieved, the operation of the solenoid valve 55 is stopped and the control oil pressure of the oil passage 51FE3 becomes the highest pressure, so that the line pressure from the oil passage 50 is not reduced and the oil passage 41
is being supplied to. Therefore, line pressure is supplied to the hydraulic chamber of the front clutch 20, and the front clutch 20
is in a state of engagement with the input shaft 19, which is not allowed to rotate.

At this time, line pressure is similarly supplied to the engagement side hydraulic chamber 36a and the release side hydraulic chamber 36b of the kickdown servo 36, but the return spring 56 pushes back the piston 53, causing it to become a rotating element. The kickdown brake 23 for a certain kickdown drum 34 is released.

When shifting from this state to 2nd gear other than by operating the select lever to 2nd gear fixed gear, the electronic control unit 54 issues a shift signal to 2nd gear depending on the driving condition of the vehicle and activates the solenoid valve. 44 is energized, the oil passage 46 is opened, and the hydraulic pressure is discharged, so that the spool 47 moves and cuts off the supply of line pressure to the 2-3 shift valve 70. As a result, the hydraulic pressure that was being supplied from the oil passage 64 to the oil passage 62 via the 2-3 shift valve 70 is cut off, and the hydraulic chamber of the front clutch 20 and the release side hydraulic chamber 3s6b of the kickdown circuit 36 are cut off.
hydraulic pressure is discharged through oil passages 59, 62, and 65. Therefore, the front clutch 20 is released, and the hydraulic pressure supplied to the maintenance side hydraulic chamber 36a causes the shift piston 53 to move against the return gear cylinder 56, thereby applying the kickdown brake 23 to the kickdown drum 34. engage to achieve second speed. Here, the engagement side hydraulic chamber 36a
The hydraulic pressure supplied to the kickdown drum 34 is supplied to a rotation speed sensor 60 of the kickdown drum 34, and a sensor 6 that detects the single speed from the output shaft 33.
1. Electronic control that receives information from various sensors that detect operating conditions, such as a sensor 80 installed in the engine intake system that detects the opening of the throttle valve, and a switch 81 that detects when the kickdown brake 23 starts engaging. By controlling the TAT valve 5 upper 5 utility III with the device 54, the supply degree (increase degree) is controlled, and smooth gear shifting with less shock is achieved.

Further, the detailed structure and operation of the automatic transmission control device as described above can be found in Japanese Patent Application Laid-Open Nos. 58-46258 and 58
Since it is disclosed in Japanese Patent No.-65355, etc., the explanation here will be omitted.

<Problems to be Solved by the Invention> Conventionally, when a vehicle is decelerating, the downshift line for executing the gear change from the third gear to the second gear is set at a low vehicle speed and a low throttle valve. Since the shift shock would be large in the opening range, this setting was not made (see FIG. 2; however, the solid line in the figure is the town shift line according to the present invention). In other words, in the above range, there is almost no difference in engine speed between 3rd gear and @22nd gear.
Since the synchronization is completed within a short time after the start of gear shifting, the kickdown switch is activated at the same time as the synchronization is completed.
It has been difficult to control the degree of increase in the oil pressure supplied to 35. Furthermore, from the viewpoint of vehicle running conditions, the above range is a region where in-vehicle noise is low, slight shift shocks and accompanying noises are large, greatly deteriorating ride comfort.

For this reason, with conventional automatic transmissions, when the vehicle decelerates and enters the operating state within the above range, it is necessary to gradually press down on the accelerator pedal and gradually increase the throttle valve opening. The engine had to accelerate while remaining in third gear, and the power performance was insufficient.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a shift control method for an automatic transmission for a vehicle that realizes the shift from the above-mentioned third speed to the second speed without causing a shift shock. shall be.

Means for Solving the Problems> The shift control method for the automatic transmission for a vehicle of the present invention comprises an input shaft to which the rotational power of the engine is input, an output shaft to output the rotational power to the drive wheels, and a hydraulic a frictional engagement element that operates to change the gear ratio between the input shaft and the output shaft by selecting an arbitrary rotational speed; and an electronic control element that controls hydraulic pressure supplied to the frictional engagement element. In the automatic transmission for a vehicle equipped with a control device, a downshift line for shifting from a high speed gear to a low speed gear when the vehicle decelerates to a predetermined vehicle speed is set in the electronic control device, The present invention is characterized in that when shifting from a gear to a low gear, the hydraulic pressure supplied to the frictional engagement element that achieves the low gear is gradually increased from a value set according to the throttle valve opening.

Effect> In order to shift from a high gear to a low gear according to the downshift line according to the present invention, the supplied hydraulic pressure is gradually increased from a value corresponding to the throttle valve opening, that is, the output state of the engine. This is accomplished in a smooth manner without causing shock due to sudden engagement.

Embodiment An embodiment in which the present invention is applied to the automatic transmission for a vehicle described above with reference to FIGS. 5 and 6 will be described with reference to FIGS. 1 to 4.

The present invention is carried out by the electronic control unit 54 performing control according to the flowchart shown in FIG.

The shift pattern (FIG. 2) stored in this electronic control system [54] for specifying the gear shift timing includes a shift pattern (Fig. The shift line (solid line in Figure 2) has been set, and the overall downshift line from 3rd gear to @2nd gear is the same as the conventional downshift line, and the newly set downshift line (solid line). The low vehicle speed portion of the conventional downshift line, which is the solid line in Figure 2, has been removed. In addition, the oil pressure supply pattern to the kickdown servo 36 during the shift from the third speed to the second speed (Fig. 3), and the relationship between the engagement start oil pressure A of the kickdown servo 23 and the throttle valve opening degree. (Figure 4) also has an electronic control system wi
, 54.

First, the sensor 61 detects the single speed and the sensor 80 detects the throttle valve opening, and based on the shift pattern shown in FIG. to decide. As a result, in the above state, the electromagnetic valves 43 and 44 that control the gears are switched from the third speed state to the second speed state. Then, the solenoid valve 55 is tilted toward the duty side, and as shown in FIG.
3 to the state just before consolidation.

Note that the state immediately before the guarantee is detected by the switch 81. In this way, when the kickdown brake 23 is about to engage, the fourth brake is applied based on the throttle valve opening.
From the relationship shown in the figure, the oil pressure A is relatively low to maintain the above state.
is determined, and the duty rate for producing this oil pressure A is commanded to the t-magnetic valve 55. This state immediately before engagement is such that the kickdown brake 23 and the kickdown drum 34 are in contact with each other.

The oil pressure A that maintains this state is determined according to the throttle valve opening, so if the throttle valve opening is large and the engine has a large output, the engine will not blow up and overrun. Also, when the throttle valve opening is small and the engine does not have much output, the kickdown brake 23 will not be suddenly engaged and shift shock will not occur. Next, the hydraulic pressure supplied to the engagement-side hydraulic chamber 36a of the kickdown serve 36 is gradually increased from the hydraulic pressure A to reach a synchronization completion state detected by the sensor 60. This increase in oil pressure is delayed enough to overcome the return spring 56.The piston 53 gradually moves and the kickdown brake 23 gradually engages the kickdown drum 34, without causing a shift shock. Synchronization is achieved. Next, the solenoid valve 55 is duty-controlled to supply hydraulic pressure to the maintenance side hydraulic chamber 36 & at a higher rate of rise, absorbing the slight /J% deviation in synchronous rotation and shifting from 3rd speed to 2nd speed. Complete shifting.

Although the relationship line between the oil pressure A and the throttle valve is shown as a straight line in the above embodiment, this relationship line may be set in various curved shapes depending on the power performance of the engine. Also, downshifting from 3rd gear to 2nd gear) [(LOL in Figure 2)
is a downshift line from @4th gear to 3rd gear and @3rd gear to 1st gear within the range where the throttle valve opening is small and the single speed is low.
However, within this condition, various configurations can be taken. In addition, the gears to which the present invention is applied range from 3rd gear, which is a high gear, to M, which is a low gear.
Although this was explained as a way to avoid confusion in 2nd gear, this 3rd gear or @2nd gear cannot be determined unconditionally depending on the characteristics of the vehicle, engine performance, etc. The present invention can be applied to demere.

<Effects of the Invention> According to the present invention, it is possible to downshift gears that could not be performed conventionally, that is, to shift from a high gear to a low gear while driving at low speed deceleration with a small throttle valve opening. This can be carried out smoothly without causing shock, and the power performance of the vehicle can be improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart according to an embodiment of the present invention, and FIG.
The figure is a shift pattern diagram, Figure 3 is a hydraulic pressure supply pattern diagram, Figure 4 is a diagram of the relationship between hydraulic pressure and throttle valve opening, Figure 5 is a schematic diagram of the automatic transmission, and Figure 6 is a diagram of the hydraulic control system. It is a schematic block diagram. In the drawing, 11 is the engine, 19 is the input shaft, 23 is the kickdown brake, 33 is the output shaft, 34 is the kickdown drum, and 36 is the kickdown serve. 43, 44, 55 are TA valves, and 54 is an electronic control device.

Claims (1)

[Claims] An input shaft to which the rotational power of the engine is input, an output shaft to output the rotational power to the drive wheels, and a speed change between the input shaft and the output shaft by operating hydraulically and selecting an arbitrary rotational element. In an automatic transmission for a vehicle that includes a frictional engagement element that switches a ratio and an electronic control device that controls hydraulic pressure supplied to the frictional engagement element, when the vehicle decelerates to a predetermined vehicle speed, the transmission changes to a high speed. A downshift line for shifting from a high gear to a low gear is set in the electronic control device, and when changing from the high gear to a low gear, the hydraulic pressure supplied to the frictional engagement element that achieves the low gear is controlled by opening the throttle valve. A speed change control method for an automatic transmission for a vehicle, characterized in that the speed change is gradually increased from a set value depending on the speed.