JPS62177356A - Method for controlling automatic transmission - Google Patents

Abstract

PURPOSE:To improve transmission efficiency by forbidding an overdrive condition in accordance with the temp. of the working fluid of a torque converter. CONSTITUTION:In an electronic control type automatic transmission having an engine 10, a four-stage automatic transmission 20 with an overdrive, a microcomputer ECU30, and an OD switch 40, signals from a throttle opening sensor 14, a water temp. sensor 16 for detecting the cooling water temp. of the engine 10, the gear position of speed change, a vehicle speed sensor 24, and an oil temp. sensor 28 in an oil pan 26, are inputted into the input part 30a of the ECU30. The microcomputer ECU30 judges whether the oil temp. TO of the transmission is higher than a prescribed temp. TOO or not and, when judged higher, the shift of gear to the overdrive OD stage is forbidden.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a method for controlling an automatic transmission equipped with an overdrive for a vehicle such as an automobile.

[Prior Art] Automatic transmissions equipped with overdrive are usually provided with a switch that prohibits shifting to overdrive. This switch is used to prohibit overdrive even when the conditions related to the throttle opening and vehicle speed for shifting to overdrive are met, and the overdrive is manually operated by the driver from the driver's seat. Conventionally, two types of switches are provided: a switch and a water temperature switch that automatically operates depending on the engine cooling water temperature.

The manual overdrive switch is used when the driver desires more agile driving performance, while the water temperature switch is used when the engine has not warmed up enough and the engine output torque is at its original state. This is to prevent overdrive, where the drive wheel torque is the smallest when the torque is lower than , to ensure smooth driving by 1q. This water temperature switch is also used to prevent the engine speed from becoming too low and to help warm up the engine.

[Problem to be Solved by the Invention J] Since the overdrive has a small reduction ratio, the rotational resistance torque of the drive wheels is applied to the output shaft side of the torque converter with almost no reduction. Therefore, if the engine output is increased all at once when the running resistance of the vehicle is large, such as when driving at high speeds, the difference in rotational speed between the input shaft side and the output shaft side of the torque converter of the automatic transmission will increase. As a result, the temperature of the hydraulic fluid in the torque converter begins to rise. Torque converter hydraulic oil is used in automatic transmissions as lubricating oil for gears, as well as hydraulic oil for gear locking brakes and gear engagement clutches, and in hydraulically controlled automatic transmissions, as control pressure for detecting shift points. It is also used as an oil,
If such a rise in oil temperature continues, the following problems will occur. In other words, the transmission efficiency of the torque converter itself decreases, the lubrication performance of the gear unit decreases by 1, and the shift point of the control unit shifts.

[Means for solving the problems] The present invention has been made to solve these problems.
As shown in Figure 1, in a control method for a vehicle automatic transmission that is equipped with a hydraulic torque converter and controls overdrive, the temperature of the working fluid of the torque converter is detected (△), and depending on the temperature (B). The gist of this invention is a method for controlling an automatic transmission characterized by (C) prohibiting an overdrive state.

[Function] When running resistance is large in an overdrive state, such as during continuous high-speed running, the temperature of the working fluid of the torque converter of the automatic transmission increases. At this time, the temperature of the working fluid is detected by a temperature sensor installed in the fluid reservoir, etc., and if the temperature is higher than a predetermined value, a temperature sensor is used to prevent the temperature of the working fluid from rising further. Release overdrive. If the automatic transmission is not in an overdrive state when the detected temperature of the working fluid is higher than a predetermined temperature, the automatic transmission is prevented from being in an overdrive state.

[Example] A first example of the present invention will be described. FIG. 2 is a configuration diagram showing an automobile engine, an electronically controlled automatic transmission, and a control device thereof. In this embodiment, engine 10. 4-speed automatic transmission with overdrive (OD) 20. The main components are a microcomputer (ECU) 30 and an OD switch 40.

The opening degree of the throttle valve 12 of the engine 10 is detected by the throttle opening sensor 14, and is input to the input section 30a of the ECU 3O. Similarly, the temperature of the cooling water of the engine 10 is detected by the water temperature sensor 16 and input to the input section 30a of the EC (J30).In the automatic transmission 20, the position of the selector lever, that is, P (parking), R (reverse), Neutral to N), L (1st stage fixed), 2 (1st stage fixed)
．． The neutral start switch 22 is in each position of
and is input to the input section 30a of the ECLI. Further, the rotational speed of the output shaft of the automatic transmission 1120 (which is proportional to the vehicle speed) is detected by the vehicle speed sensor 24, and the oil temperature of the automatic transmission R20 is detected by the oil temperature sensor 28 installed in the oil pan 26. , both ECU3
The signal is input to the input section 30a of O.

In addition to these signals, the input unit 30a of the ECLI 30 also receives a signal from an OD switch 40 that is operated by the driver to prohibit the automatic transmission from going into the OD state. ECU
3O is the input section 30a mentioned above, as well as the CPU 30b and RO.
M30c, RAM30d.

It consists of an output section 30e and a bus 30f that sustains them. A command signal is outputted to the automatic transmission 20 from the output section 30e.

The processing executed in the ECLJ 30 will be explained based on the flowchart of FIG. 3, focusing on the operation of the embodiment according to the present invention. First, in steps 100 and 110, the position sw of the OD switch 4o is input, and it is determined whether it is ON. The OD switch 40 is operated by the driver in order to obtain agile driving performance of the vehicle.

If the OD switch 40 is OFF, step 120
Flag FOD1. :O is assigned. FOD is OD
A flag indicating whether the state is prohibited or not, FOD
When =O, the 00 state is prohibited.

If it is determined in step 110 that the OD switch is ON, then in steps 130 and 140 the engine coolant temperature TW is input, and it is determined whether it is higher than a predetermined temperature TWO.

If the cooling water wetness TW is lower than the TWO, the process goes to step 1.
Moving on to step 20, O is assigned to the flag FOD in the same way as above. This prohibits the OD state in order to reduce the load on the engine and promote warm-up of the engine when starting the engine in cold weather.

When it is determined in step 140 that TW>TWOl, that is, the engine has been warmed up, the oil temperature TO of the transmission is inputted in steps 150 and 160, and it is determined whether or not it is lower than a predetermined temperature TOO.

Here, if the oil temperature To is determined to be higher than ToO,
At step 120, 0 is assigned to the flag FOD.

OD switch SW is ON, cooling water ITW is TWO
If it is determined that the oil (W T O ) is higher than Too and the oil (W T O is lower than Too When O is assigned to , it is then determined in step 180 whether or not the automatic transmission 20 is currently in the OD state, and if it is in the OD state, step 1 is performed.
At 90, the automatic transmission 20 is commanded to cancel the release,
Proceed to step 200. If it is determined that the current state is not OD, the process directly advances to step 200.

In step 200, the throttle opening and vehicle speed are input, and in step 210, these values are compared with a predetermined shift pattern to determine whether the current moment corresponds to a shift point. If the current point does not correspond to a shift point, this routine ends here, but if it does, then in step 220, it is determined whether the shift point is a shift from 3rd gear to 00th gear. is judged. If not, immediately step 2.
At step 40, the automatic shift 120 is commanded to execute a shift corresponding to that shift point.

If it is determined in step 220 that the shift point is the shift point to the OD gear, then in step 230 the flag FOD
The value of is checked, and only when FOD=1, the automatic transmission is commanded to shift to 00 gear. If FOD=O, no shift command is issued and this routine ends.

As described above, in this embodiment, in addition to the conventional control using only the OD switch 40 and the engine cooling water 4TW, the oil temperature of the automatic shift R20 is also referred to to perform control to prohibit shifting to the 00 gear. The oil temperature of the automatic transmission 20 is always maintained at an appropriate level without increasing excessively. Figure 4 is OD
This is a graph showing the relationship between the vehicle speed during constant speed driving and the oil temperature of the automatic transmission in the third gear and third gear, and it is shown that the oil temperature decreases by prohibiting the OD gear. . For this reason, each part of the automatic transmission always exhibits good performance,
Effects such as improved transmission efficiency in the torque converter and improved durability in the gear unit can be obtained.

Next, an embodiment in which the method according to the present invention is applied to a hydraulically controlled automatic transmission will be described. Figure 5 (A> is 3 which detects the shift point from the 3rd stage to the OD stage in the hydraulic circuit of the automatic transmission.
-OD shift valve 50° 3-00 Solenoid pulp 60 for controlling the oil pressure of the shift valve 50 to the third coast shift pulp 51. Switch 70° of solenoid valve 60 72.74. FIG. 2 is a configuration diagram showing a planetary gear device 80 and the like related to shifting from the third stage to the OD stage of the automatic transmission. The operation of this embodiment will be explained below.

Among the switches 70, 72, and 74, 70 is the same OD switch as in the previous embodiment, 72 is an engine coolant temperature switch, and 74 is an automatic transmission oil temperature switch. The switch 72 is set to be turned off when the water temperature becomes lower than a predetermined temperature, and the switch 74 is set to be turned off when the oil temperature becomes higher than another predetermined temperature.

When all three switches 70, 72, and 74 are ON (FIG. 5(A)), the plunger 62 of the solenoid valve 60 opens the orifice 64, so the line pressure 66 is applied to the third of the 3-OD shift valve 50. It does not act on the upper part of the coast shift valve 51. In this case, the 3-OD shift control valve 52 can move up and down according to the magnitude relationship between the governor pressure 53, which changes according to the vehicle speed, and the throttle pressure 54, which changes according to the throttle opening. . Therefore, the line pressure 55 is equal to the clutch pressure 5
6 or brake pressure 57. In the planetary gear system 80, the clutch 8
1 and the brake 82 engage and lock each gear of the planetary gear 83 by the action of the clutch pressure 56 and the brake pressure 57, respectively, and shift from the 3rd gear to the 00 gear or from the 00 gear to the 3rd gear. Achieve speed change.

Note that 84 is an input shaft, and 85 is an output shaft.

On the other hand, when the oil temperature of the automatic transmission rises above a predetermined temperature and the switch 74 is turned OFF, as shown in FIG. 5(B).
As shown, the plunger 62 of the solenoid pulp 60 closes the orifice 64. For this reason, line pressure 66
pushes down the third coast shift valve 51 and 3-OD shift control valve 52, and the line pressure 55 is the clutch brake? Only 56 is taken and the clutch 81 is operated, and the 00th stage is not realized.

As is clear from this embodiment, the automatic transmission control method according to the present invention can also be used in a hydraulically controlled automatic transmission. In this case, the shift point is determined based on the magnitude of the oil pressure, so by prohibiting shifting to OD, the oil temperature can be maintained at an appropriate level, which stabilizes the oil pressure and allows accurate shift control. This effect also occurs.

〔effect〕

By employing the automatic transmission control method according to the present invention, excessive temperature rise of the working fluid of the automatic transmission can be prevented, and the fluid temperature can always be kept within an appropriate range. For this reason, the transmission efficiency of the torque converter is improved, and the lubrication performance of the gear unit is improved, making the gears more durable. This has the effect of enabling accurate speed change control.

In addition, the present invention also has the effect that it becomes possible to eliminate or reduce the capacity of the oil cooler that has been conventionally installed to lower the oil temperature of automatic transmissions.

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the basic procedure of the present invention, Fig. 2 is a configuration diagram of the first embodiment, Fig. 3 is a flowchart of processing executed by the ECU of the first embodiment, and Fig. 4 is a graph showing the relationship between vehicle speed and automatic transmission oil temperature, Figure 5 (
A) and (B) are explanatory diagrams showing the operation of the second embodiment. 10...Engine 20...Automatic transmission 28...Oil temperature sensor 30...Microcomputer (ECU) 50...
3-OD shift valve 60...Solenoid pulp

Claims (1)

[Claims] 1. A method for controlling a vehicle automatic transmission equipped with a hydraulic torque converter and having an overdrive, which detects the temperature of the working fluid of the torque converter and prohibits the overdrive state according to the temperature. A method for controlling an automatic transmission, characterized in that: 2. The automatic transmission control method according to claim 1, wherein the overdrive state is prohibited when the temperature of the working fluid rises above a predetermined temperature.