JPH04140556A - Control device for four-wheel drive vehicle with automatic transmission - Google Patents

Abstract

PURPOSE:To secure durability desirable even with large load acting upon a friction element during four-wheel drive by setting the speed change time during four-wheel drive shorter than that during two-wheel drive to perform oil pressure control at the speed change time of an automatic transmission. CONSTITUTION:Whether or not two-wheel drive is selected is discriminated by 2-4 switching mechanism 7. At the time of two-wheel drive, the target speed change time T is set to the set time T1. At the time of four-wheel drive, the oil temperature of an automatic transmission A is discriminated, and the target speed change time T is set to T2 at the normal time when the oil temperature is less than the set value. In this case, the target speed change time T2 at the time of four-wheel drive is set shorter than the target speed change time T1 at the time of two-wheel drive. The target speed change time T3 under high oil temperature is set shorter than the target speed change time T2 under normal temperature. A duty solenoid valve is then controlled in such a way that the actual speed change time becomes the target speed change time T1, T2 or T3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a control device for controlling the shift time of an automatic transmission in a four-wheel drive vehicle with an automatic transmission.

(Prior Art) Conventionally, regarding the control of the shift time in an automatic transmission, a target value of the shift time is set and the actual shift time is measured, as disclosed in Japanese Patent Publication No. 6B-3183, for example. Then, the system repeatedly learns to correct the oil pressure for the friction element at each gear shift so that this actual value converges to the target value.
It is known that the actual value is gradually converged to the target value as the speed change is repeated.

(Problems to be Solved by the Invention) Some four-wheel drive vehicles are equipped with a 2-4 switching mechanism that selectively switches power transmission between two predetermined wheels and all wheels.

However, in a four-wheel drive vehicle such as the one described above, when learning control is performed to change the actual value of the shift time to the target value, even if the shift time is appropriate when the vehicle is in two-wheel drive, the drive load increases when the vehicle is in four-wheel drive. As a result, the oil temperature in automatic transmissions is likely to rise, so there are two types of friction elements in automatic transmissions.
Compared to wheel drive, a large load is applied throughout the shift time, resulting in a disadvantage of reduced durability.

The present invention has been made in view of the above, and its purpose is to set hydraulic control in an automatic transmission so as to appropriately change the shift time between two-wheel drive and four-wheel drive. The objective is to ensure good durability even when a large load is applied to the friction elements during four-wheel drive.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an automatic transmission equipped with a 2-4 switching mechanism that selectively switches power transmission between two predetermined wheels and all wheels. Assuming that the vehicle is a four-wheel drive vehicle, a switching state detection means detects the state of power switching to the wheels by the 2-4 switching mechanism, and between two-wheel drive and four-wheel drive detected by the switching state detection means, The automatic transmission is configured to include a setting means for setting hydraulic control during shifting in the automatic transmission in a direction in which the shifting time in four-wheel drive is shorter than that in two-wheel drive.

(Function) With the above configuration, in the present invention, when the automatic transmission is in four-wheel drive, a large load is applied to the friction element when shifting the automatic transmission, but since the shifting time is shorter than that in two-wheel drive, its durability is improved. Good reliability is ensured.

(Effects of the Invention) As explained above, according to the control device for a four-wheel drive vehicle with an automatic transmission of the present invention, the shift time in the automatic transmission can be made different between two-wheel drive and four-wheel drive. However, when using 4-wheel drive, it is short (
Since the hydraulic control of the automatic transmission is set to achieve this, it is possible to improve the durability and reliability of the friction elements during four-wheel drive, where the drive load increases.

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

Fig. 1 shows a schematic configuration of the main parts of an automatic transmission A in a four-wheel drive vehicle, in which 1 is a main transmission mechanism, and 2 is a two-stage system that controls the rotation of the output shaft 1a of the main transmission mechanism 1 in a direct connection state and a deceleration state. The output shaft 2a of the sub-transmission mechanism 2 is a sub-transmission mechanism that switches to
It is connected to the left and right rear wheels via a propeller shaft, differential device, etc. (not shown).

Reference numeral 5 denotes a second output shaft disposed parallel to the output shaft 2a of the sub-transmission mechanism 2, and the second output shaft 5 is connected to the left and right sides via a propeller shaft, differential device, etc. (not shown). Connected to the front wheel.

The output shaft 2a of the sub-transmission mechanism 2 and the second output shaft 5
A 2-4 switching mechanism 7 is arranged between. Part 2
-4 The switching mechanism 7 includes a sprocket 8 rotatably disposed on the output shaft 2a of the sub-transmission mechanism 2, a driven sprocket 9 integrally formed on the second output shaft 5, and a chain 10 wound around both. and further includes an auxiliary transmission mechanism 2.
a gear 11 integrally formed with the output shaft 2a of the output shaft 2a;
It is provided with a switching sleeve 12 that connects and releases the gear 11 and sprocket 8 on the gear a. and,
Isu shifting a! ! When the switching sleeve 12 is positioned on the output shaft 2a of the sub-transmission mechanism 2 at the release position where the connection between the gear 11 and the sprocket 8 is released, the power is transmitted from the output shaft 2a of the sub-transmission mechanism 2 only to the rear wheels. On the other hand, when the switching sleeve 12 is positioned at the connecting position where the gear 11 and the sprocket 8 are connected by the switching sleeve 12, the second output is also transmitted from the output shaft 2a of the sub-transmission mechanism 2. Axis 5
The structure is such that power is also transmitted to the front wheels via the 4-wheel drive system.

Further, in FIG. 1, reference numeral 15 denotes a controller having a CPU or the like therein, and outputs a two-wheel drive command signal or a four-wheel drive command signal from the controller 15, and outputs the above-mentioned 2-4
A duty electromagnetic valve S of a hydraulic circuit for line pressure control shown in FIG. 2, which will be described later, is configured to selectively position a switching sleeve 12 of a switching mechanism 7 between a release position and a connection position.

The configuration is such that a control signal for line pressure control is output to L. Furthermore, a signal from an oil temperature sensor 16 that detects the temperature of internal oil in the automatic transmission A is input to the controller 15.

Next, a line pressure control circuit in the hydraulic circuit for speed change control of the automatic transmission A will be explained with reference to FIG. In the figure, 20 is a hydraulic pump, and 21 is a reducing valve connected to a discharge line 20a of the hydraulic pump 20, which reduces the discharge pressure to a constant set pressure and supplies it to the pressure line 22.
It's a valve.

25 is a modulator connected to the pressure line 22.
The valve 25 has a pilot pressure of a pilot passage 26 acting on the right end of the spool 25a in the figure, and has a duty solenoid valve SQL.
The hydraulic pressure acting on the left end of 5a in the figure is transferred to the duty solenoid valve S.
By adjusting QL, the hydraulic pressure in the pressure line 22 is reduced, and the hydraulic pressure corresponding to the duty rate of the duty electromagnetic valve SQL is supplied to the pilot passage 26.

Further, 27 is a pressure regulator valve, and the pilot pressure of the pilot passage 26 acts on the pressure receiving surface at the left end of the spool 27a in the figure, while the other side of the spool 27a is the pressure receiving surface of the hydraulic pump 20. Hydraulic pressure in line 20b is acting. And this spool 2
By adjusting the amount of movement of the spool 27a in relation to the pilot pressure and pump discharge pressure acting on both left and right ends of the discharge line 6a, and connecting the discharge line 20b to the drain passage 28 or blocking this communication, the discharge line The oil pressure of 20b, that is, the line pressure, is adjusted to the oil pressure according to the pilot pressure.

Incidentally, an accumulator 29 is connected to the pilot passage 26 for absorbing and alleviating the pulsation of the pilot pressure.Next, shift control of the automatic transmission A will be explained based on the control flow shown in FIG. 3. Start, step S^1 and 2
-4 The switching mechanism 7 determines whether or not two-wheel drive is selected, and when the two-wheel drive is selected, the target shift time T is set to the set time T1 in step SA2.

On the other hand, in the case of four-wheel drive, the oil temperature of the automatic transmission A is determined in step sA3, and when the oil temperature is normally lower than the set value, the target shift time T is set to T-T2 in step SA4. Here, the target shift time opening T2 during four-wheel drive is set shorter than the target shift time T1 during two-wheel drive (T2<T1), as shown in FIG. Furthermore, when the oil temperature is at a high temperature that is higher than the set value, the target shift time T is set to T''' Ta in step SA5.The target shift time T3 at the high oil temperature is greater than the target shift time T2 at the normal temperature. is also set short (T3 x T2).

After setting the target shift time as described above, in step SA6 the actual shift time is set to the target shift time T1.
．． The duty solenoid valve SQL is controlled based on the control flow shown in FIG. 4 so that the voltage becomes T2 or T3.

The above target shift time can be controlled at step SBI in Fig. 4.
After reading the actual shift time t, the difference ΔT (-T-1) between the target shift time T (T1, T2 or T3) obtained above and the actual shift time t is calculated in step S82. Thereafter, in step SR3, the amount of change ΔP in line pressure corresponding to the deviation time ΔT is searched from the map shown in FIG.
Step S, the amount of change ΔPL in the line pressure found by the 4th lever
is stored in the backup RAM built into the controller 15, and then in step SaS the line pressure P at the time of gear change is stored.
L is searched from the map shown in Fig. 7 according to the type of shift and throttle valve opening at that time, and the line pressure PL is corrected by adding the amount of change ΔP in the line pressure, and this line pressure (P
L+ΔP1. ), and the process ends. The line pressure PL stored in the map shown in FIG. 7 is rewritten to a value obtained by adding and correcting the amount of change ΔPL in the line pressure stored in the backup RAM at the time of the next shift.

Therefore, according to step SA1 of the control flow in FIG.
A switching state detection means 17 is configured to detect the state of power switching to the wheels by the 2-4 switching mechanism 7 and detect whether the vehicle is in two-wheel drive or four-wheel drive. Also, steps SA2 and SA4
2 detected by the switching state detection means 17.
Between wheel drive and 4-wheel drive, the hydraulic control during gear shifting with automatic transmission A is changed so that the shifting time in 4-wheel drive (that is, the target shifting time T2 to be finally controlled) is the same as that in 2-wheel drive. A setting means 18 is configured to set the shift time in a direction shorter than the time (target shift time T1).

Therefore, in the above embodiment, the actual shift time t is controlled to the target value T1 during two-wheel drive, so the shift shock is effectively reduced while ensuring good durability of the friction elements of the automatic transmission A. be done.

In addition, when driving with four wheels, the driving force acts across the entire width, so when automatic transmission A changes gears, a larger load acts on its friction elements than when driving with two wheels, and the temperature of the friction elements of automatic transmission A increases. Although the situation is sudden, the target shift time T2 (T2 - T1) is shorter than the actual shift time t or 2-wheel drive.
), and the operation is completed quickly, so the temperature rise of the friction element is suppressed to a low level, ensuring good durability and reliability.

Furthermore, during four-wheel drive, the slippage in the torque converter increases due to the action of a large drive load, and the oil temperature in automatic transmission A tends to rise, making the temperature rise of the friction elements even more noticeable. ．． Tl] When the temperature is higher than the set value, the target shift time T3 (T3 x T2) is set, which is even shorter than the normal target shift time T, so the durability and reliability of the friction elements are effectively ensured. Ru.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a skeleton diagram showing the main part configuration of a four-wheel drive vehicle, FIG. 2 is a diagram showing a line pressure control circuit of an automatic transmission, and FIGS. 3 and 4. is a diagram showing shift control, Figure 5 is an explanatory diagram showing target shift times for two-wheel drive and four-wheel drive, Figure 6 is a diagram showing a line pressure change amount map, and Figure 7 is a diagram showing line pressure change. FIG. 3 is a diagram showing a map. A... Automatic transmission, 7... 2-4 switching mechanism, 12.
...Switching sleeve, 16...Oil temperature sensor, 17...
Switching state detection means, 18...setting means. A...Automatic transmission 7...2-4 switching mechanism 12 Switching sleeve 16...Oil temperature sensor Fig. Fig. Fig. A Fig.

Claims (3)

[Claims] (1) In a four-wheel drive vehicle with an automatic transmission equipped with a 2-4 switching mechanism that selectively switches power transmission between two predetermined wheels and all wheels, power switching to the wheels by the 2-4 switching mechanism described above A switching state detection means detects the state, and between the two-wheel drive state and the four-wheel drive state detected by the switching state detection means, the hydraulic control at the time of shifting in the automatic transmission is controlled to determine the shift time during the four-wheel drive state. 1. A control device for a four-wheel drive vehicle with an automatic transmission, comprising a setting means for setting the length in a direction shorter than when driving two wheels. (2) The automatic transmission according to claim (1), wherein the setting means sets the shift time during four-wheel drive to be shorter when the oil temperature of the automatic transmission is above the set value than when it is less than the set value. Control device for 4-wheel drive vehicles with transmission. (3) The automatic transmission according to claim 1, wherein the setting means sets a target value for the shift time, and sets the target value in a direction that is shorter when the gear is driven by four wheels than when it is driven by two wheels. Control device for 4-wheel drive vehicles.