JPH0242266A - Line pressure control device of automatic transmission - Google Patents

Abstract

PURPOSE:To prevent quick change in the speed change shock reducing effect because of line pressure control by varying the line pressure via the values before and after changing-over at the time of changing-over caused by oil temp. variation of the speed changing line pressure control characteristic. CONSTITUTION:An automatic transmission performs speed changing by engaging selectively friction elements with line pressure, and during this speed changing a speed changing line pressure control means controls the line pressure by reference to the line pressure control characteristic corresponding to the working oil temp. sensed by an oil temp. sensor. Thus speed change shocks are reduced. When the line pressure control characteristics are altered according to the working oil temp., a line pressure transient control means varies for ex. the line pressure continuously via value between before and after alteration of the characteristic in compliance with signals from a sensing means which senses such alteration of line pressure control characteristic, and thus abrupt change in the line pressure is suppressed. Thus abrupt change of the speed change shock reducing effect due to line pressure control is prevented at the time of changing-over the speed changing line pressure control characteristic resulting from oil temp. variation to contribute to elimination of uncomfortable sense.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for controlling the line pressure of an automatic transmission so as to reduce shift shock during gear shifting.

(Prior art) Automatic transmissions select a predetermined gear by selectively hydraulically operating various friction elements (clutches, brakes, etc.) using line pressure, and shift to other gears by changing the activated friction elements. is possible.

By the way, during this shift, a shift shock inevitably occurs due to the change in gear ratio, and the magnitude of this shift shock is determined by the engagement capacity of the friction element that is activated during the shift, that is, the amount supplied to this operation. It depends on the level of line pressure. That is, the more the line pressure during gear shifting is too high and the capacity of the friction element is excessive, the greater the gear shifting shock becomes. However,
If the line pressure during gear shifting is too low and the capacity of the friction element is insufficient, a gear shifting shock will not occur, but the friction element will slip violently, impairing durability.

However, the line pressure suitable for alleviating shift shocks varies not only depending on the type of shift and the transmitted torque (usually determined by the throttle opening), but also varies depending on the temperature of the transmission hydraulic fluid. Therefore, conventionally, for example, as shown in FIG. 4, line pressure characteristics PH for high temperatures and line pressure characteristics PL for low temperatures (
Characteristics related to throttle opening TH) are prepared for each type of shift, and the set hydraulic oil temperature t3 is set as shown in Fig. 8(a).
The applicant of the present invention is currently using a technique for searching for line pressure P by searching for PL at less than t2 and Pl at or above t2 for the R84R old ^ type automatic transmission.

(Problems to be Solved by the Invention) However, in this lever technique, the line pressure suddenly changes after the hydraulic oil temperature t1, and the instantaneous shift shock reduction effect also changes suddenly, giving the occupant a sense of discomfort.

An object of the present invention is to solve the above-mentioned problem by changing the line pressure via the values before and after the change when changing the line pressure control characteristic for shifting.

(Means for Solving the Problem) For this purpose, the present invention, as conceptually shown in FIG. In an automatic transmission, the line pressure is controlled by a line pressure control means for shifting according to a line pressure control characteristic with respect to a working oil temperature detected by an oil temperature sensor during a shift to change a selected gear position. It is equipped with line pressure characteristic change detection means for detecting switching, and line pressure transient control means for changing the line pressure at the time of switching of line pressure control characteristics via the values before and after the switching. be.

The line pressure transient control means is preferably of a type that continuously changes the line pressure from a value before the line pressure control characteristic is switched to a value after the line pressure control characteristic is switched.

(Function) An automatic transmission selectively hydraulically operates various friction elements using line pressure to select a predetermined gear, and transmits power at this gear. Furthermore, automatic transmissions can shift to other gears by changing the friction elements that operate.

During this shift, the shift line pressure control means controls the line pressure in accordance with line pressure control characteristics corresponding to the transmission working oil temperature detected by the oil temperature sensor, thereby reducing shift shock.

By the way, when the line pressure control characteristics change according to the hydraulic oil temperature, in response to a signal from the line pressure characteristic change detection means that detects this, the line pressure transient control means changes the line pressure control characteristics via the values before and after the characteristic change. Change the pressure. Therefore, it is possible to prevent a sudden change in the line pressure when changing the line pressure control characteristic, and it is possible to eliminate the discomfort caused by a sudden change in the shift shock reduction effect.

In addition, if the line pressure transient control means is one that continuously changes the line pressure from the value before switching to the value after switching when the line pressure control characteristics are switched, the change in line pressure is sufficiently smooth. Therefore, changes in the gear shift shock reduction effect can be made almost indiscernible.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows an embodiment of the present invention, where 1 represents an engine and 2 represents an automatic transmission.

The engine 1 is operated with the ignition timing and fuel injection amount determined by the engine control computer 3. Therefore, the computer 3 receives a signal from a sensor 4 that detects the engine rotation speed N5 and a sensor 5 that detects the engine throttle opening TH. The signals from each person are manually transmitted.

The automatic transmission 2 receives the power of the engine 1 via the torque converter 6, and can transmit this power to the output shaft 7 at a gear ratio according to the selected gear position to drive the vehicle.

A control valve 8 is provided to control the speed change of the automatic transmission 2, and this control valve incorporates an il and second shift solenoid 9, 10, and a line pressure solenoid 11.

These solenoids 9 to 11 are controlled by the automatic transmission control computer 12, and by turning on and off the shift solenoids 9 and 10 in the combinations shown in the following table,
In the automatic transmission 2, friction elements (not shown) are selectively hydraulically actuated by line pressure, and a corresponding gear stage can be selected.

Table 1 Note that the line pressure is controlled by changing the drive duty D of the solenoid 11.

In order to perform such speed change control and line pressure duty control, the computer 12 inputs information regarding the throttle opening TH from the sensor 5 as well as the output shaft 70 rotation speed N.

(vehicle speed), a signal from a sensor 14 that detects the transmission rotational speed N, and a signal from an oil temperature sensor 15 that detects the transmission hydraulic oil temperature t.

FIG. 3 is a program for the computer 12 to perform line pressure control for shifting according to the present invention. That is, first, in step 20, it is checked whether or not the gear is being shifted. If not, the line pressure control according to the present invention is not necessary, so in step 21, the line pressure P for non-shifting is determined as usual.

If shifting is in progress, the following line pressure control is performed for each type of shifting. In other words, in step 22.23, whether the transmission hydraulic oil temperature t is lower than the set temperature 1+ (see Figure 8) or the set temperature t
Check whether the temperature is higher than z (see Figure 8) or in the transition region between 1° and t2. If the temperature is low, the corresponding line pressure control characteristic PL in FIG. 4 is searched in step 24.25, and a search value corresponding to the throttle opening TH is set to the line pressure P. A corresponding line pressure control characteristic PH is searched, and a search value corresponding to the throttle opening TH is set to the line pressure P. If it is in the transition region, in step 28, as the hydraulic oil temperature t changes, as shown in FIG. ' (or PL) is calculated to set the line pressure P to a value that gradually changes.

In step 29, step 21.25.27 or 28
The duty D corresponding to the set line pressure P is determined in step 30, and this is output to the solenoid 11 in step 30, thereby controlling the line pressure P as determined above.

By the way, during gear shifting, the line pressure P is controlled as shown in FIG. 8(b) for each type of gear shifting and throttle opening as described above, and the characteristics PL, PI ( Not only can the shift shock be reliably reduced by controlling the line pressure along the t1≦t<t2 transition region, but it is also possible to eliminate the discomfort caused by the sudden change in the shift shock reduction effect described above by gradually changing the line pressure in the transition region of t1≦t<t2. can.

FIG. 5 and FIG. 6 show another example of the present invention, and this example is directed to the above-mentioned device in which the line pressure is learning-controlled so that the shift time becomes the target shift time that should be targeted for reducing shift shock. This is an example of application of the idea of the present invention.

FIG. 5 shows a correction program for the line pressure correction amount using the above-mentioned learning control.In step 40, it is checked whether or not the gear is being changed. If the shift is not in progress, there is no need to correct the line pressure correction amount, so the control is ended as is, and the line pressure is corrected as follows during the shift. That is, in step 41 it is checked whether or not the shift time is already being measured. If it is not being measured yet, in step 42 the transmission output rotation speed N is determined. The transmission output rotation speed N is found by multiplying by the pre-shift gear ratio iA. It is checked whether or not to start shifting based on whether or not the input rotational speed NT deviates from XIA. In step 43 at the time of starting the shift, a timer for measuring the shift time is activated to start measuring the shift time.

As a result, when the shift time is being measured, in step 44, the post-shift input rotation speed N is determined by multiplying the transmission output rotation speed No. by the post-shift gear ratio IB. It is checked whether or not the shift has been completed based on whether or not the input rotational speed N7 matches xlB. Until the end of the shift, the control is ended and the timer continues to measure time, and at the end of the shift, in step 45, the timer is stopped and the measurement of the shift time is ended. and step 46
Then, the line pressure correction book ΔP or ΔPL for bringing the shift time closer to the target shift time is corrected based on the deviation between both supports.

Here, ΔPH is the line pressure correction amount for high temperature, ΔP.

is the line pressure correction amount for low temperatures, and at high temperatures when t≧t2, ΔP corresponds to the type of shift and throttle opening Tll.

The stored data of 1<1. is corrected in step 46. When the temperature is low, ΔP corresponds to the type of shift and throttle opening TH.
, is modified in step 46.

Therefore, these line pressure correction amounts ΔP□.

For example, ΔP[, for each type of speed change and throttle opening varies from moment to moment as shown in FIGS. 7(a) and 7(b).

FIG. 6 is a line pressure control program based on the above learning, and steps similar to those in FIG. 3 are designated by the same reference numerals. During low temperature, in step 50, line pressure P is determined by adding up PL+ΔPL according to the type of shift and throttle opening, and during high temperature, in step 5I, PI++ΔP is calculated according to the type of shift and throttle opening.

Find the line pressure P by adding up the If it is in the transition region, in step 52, as the hydraulic oil temperature t changes, the line pressure PL+ΔP before switching the line pressure control characteristic is
1. Line pressure P after switching from (or 90△PH),
+(P+, +ΔPt,) is calculated to set the line pressure P to a value that gradually changes toward +ΔPII (or toward PL+8P).

Therefore, in this example as well, the line pressure P during gear shifting is controlled as shown in FIG. In addition to being able to reliably reduce the shock, by gradually changing the line pressure in the transition region, it is possible to eliminate the discomfort caused by the sudden change in the shift shock reduction effect.

In each of the above examples, the line pressure is continuously changed in the transition region, but the initial objective can be achieved to varying degrees even if the line pressure is controlled by a plurality of stepwise changes.

(Effects of the Invention) Thus, as described above, the line pressure control device of the present invention is configured to switch the line pressure and change it through the values before and after when the line pressure control characteristic for gear shifting changes due to changes in oil temperature. Therefore, it is possible to prevent a sudden change in the shift shock reduction effect due to line pressure control at the time of the switching, and it is possible to eliminate a sense of discomfort.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the line pressure control device of the present invention, Fig. 2 is a system diagram showing an embodiment of the inventive device, and Fig. 3 is a line pressure control program executed by the automatic transmission control computer on the same side. Flowchart, FIG. 4 is a line pressure control characteristic diagram for shifting, FIGS. 5 and 6 are flowcharts of a line pressure correction amount correction program and a line pressure control program showing other examples of the present invention, respectively, and FIG. ), (b) are change time charts of the line pressure correction amount, and FIG. 8 is a line pressure control characteristic diagram comparing the case of the conventional device and the case of the device of the present invention. ■...Engine 2...Automatic transmission 3...
・Engine control computer 4...Engine rotation sensor 5...Throttle opening sensor 6...Torque converter 7...Transmission output shaft 8...
...Control valve 9...First shift solenoid 10...Second shift solenoid 11...Line pressure solenoid 12...Automatic transmission control controller 13...Output rotation sensor 15...Oil temperature sensor side Computer 14...Manual rotation sensor

Claims (1)

[Claims] 1. A predetermined gear is selected by selective hydraulic actuation of various friction elements using line pressure, and the selected gear is switched by changing the operating friction elements. In an automatic transmission that is controlled by a line pressure control means for shifting with a line pressure control characteristic corresponding to a detected hydraulic oil temperature, the line pressure characteristic change detection means detects a change in the line pressure control characteristic; 1. A line pressure control device for an automatic transmission, comprising: line pressure transient control means for changing the line pressure at the time of switching of pressure control characteristics via a value between before and after the switching. 2. The line pressure control for an automatic transmission according to claim 1, wherein the line pressure transient control means is configured to continuously change the line pressure from a value before the line pressure control characteristic is switched to a value after the line pressure control characteristic is switched. Device.