JPH0272265A - Hydraulic controller for automatic transmission - Google Patents

Abstract

PURPOSE:To stabilize the control of a line pressure control valve and the control of the line pressure by installing a correcting means for the control value for controlling a solenoid valve for a prescribed time after the engine start. CONSTITUTION:A control unit C reads a throttle opening degree signal and a car speed signal and sets the line pressure according to a line pressure setting map stored in a ROM previously. Then, the controller reads a timer signal and an oil temperature signal and judges if the lapse time after the engine start exceeds a prescribed time or not, and if the time is not exceeded, mixing of air in an oil passage 3 is judged, and the correction duty ratio setting routine is started. Therefore, within a prescribed time after the engine start, the duty ratio of an electromagnetic solenoid 4 and the pilot oil pressure of a line pressure adjusting valve 6 are set, supposing the mixing of air into the oil passage 3, and the line pressure always satisfies the demands.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hydraulic control device for an automatic transmission, more specifically,
This invention relates to an electronically controlled automatic transmission in which hydraulic pressure is controlled by an electromagnetic solenoid.

(Prior art) An automatic transmission includes a planetary gear type transmission mechanism, a clutch for switching the power transmission path of this planetary gear type transmission mechanism,
It is equipped with a hydraulically actuated gear shifting friction element such as a brake, and gear shifting is performed in accordance with the manner in which the gear shifting friction element is engaged or released. The hydraulic pressure (hereinafter referred to as "line pressure") that operates the gear shifting friction element is generated by an oil pump and controlled by a line pressure control valve based on engine output, vehicle speed, and the like.

By the way, the line pressure control valve has conventionally been controlled by pilot hydraulic pressure controlled by mechanical means, but recently, line pressure control valves controlled by pilot hydraulic pressure controlled by electrical means have been adopted. For example, Japanese Patent Laid-Open No. 54-2349 discloses an electronically controlled automatic transmission in which a line pressure control valve is actuated by pilot oil pressure controlled by an electromagnetic solenoid.

(Problems to be Solved by the Invention) By the way, in electronically controlled automatic transmissions that control line pressure control valves using pilot oil pressure controlled by electromagnetic solenoids, the pilot oil pressure is also generated by the oil pump. When the oil pump stops when the engine stops, the oil in the pilot hydraulic circuit leaks from the valve body and flows into the oil pump's oil sump, causing air to enter the pilot hydraulic circuit. There is a problem in that the pilot oil pressure does not reach the desired value due to the influence of the mixed air, and as a result, the desired line pressure may not be obtained.

There is no problem with this point if the valve body is installed below the oil level, but
A problem arises when the valve body is mounted above the oil level due to placement constraints.

(Object of the invention) The present invention is constructed in view of the above problems, and
We have developed a hydraulic control system for automatic transmissions that can prevent the pilot hydraulic pressure from deviating from the intended value due to air intrusion into the pilot hydraulic circuit, and can stabilize the control of the line pressure control valve and, by extension, the line pressure. The purpose is to provide.

(Structure of the Invention) The above-mentioned object of the present invention is to provide a control value for controlling the electromagnetic solenoid for a predetermined period of time after engine startup in an electronically controlled automatic transmission in which hydraulic pressure (line pressure) is controlled by an electromagnetic solenoid. This is achieved by providing a correction means. According to the present invention, the electromagnetic solenoid is controlled within a predetermined period of time after the engine is started, assuming that air is mixed into the pilot hydraulic circuit, so that the pilot hydraulic pressure of the line pressure control valve does not deviate from the desired value. There isn't.

(Examples) Hereinafter, based on the attached drawings, examples of the present invention will be explained.
A hydraulic control device for an automatic transmission will be explained.

FIG. 1 is a configuration diagram of a hydraulic control device for an automatic transmission according to this embodiment.

In FIG. 1, the hydraulic pressure generated by a pump P passes through an oil line 1 and is reduced to a predetermined pressure by a pressure reducing valve 2, and this reduced oil pressure passes through an oil line 3 and is passed through an electromagnetic solenoid 4.
The pressure is regulated by.

As shown in an enlarged view in FIG. 2, the electromagnetic solenoid 4 includes a solenoid winding 4a, a valve element 4b in the core of the solenoid winding 4a, and an oil passage 4C branching off from the end of the oil passage 3.
, a drain oil passage 4d, and a valve spring 4e. In normal state B (when the electromagnetic solenoid 4 is in the OFF state B), the valve element 4b is pressed toward the right in FIG. 2 by the valve spring 4e, and the valve element 4b seals the oil passage 4C. When the solenoid winding 4a is energized (the electromagnetic solenoid 4 is ON! 14), the valve element 4b moves to the left to open the oil passage 4C, and the oil in the oil passage 3 flows through the drain oil passage 4d. The oil is discharged to the oil pan, and the oil pressure in the oil passage 3 drops. Therefore, by controlling the ratio of the ON state and OFF state time of the electromagnetic solenoid 4 (○N state time 10FF state time), that is, the duty rate, the oil pressure in the oil passage 3 is adjusted (the duty rate is The higher the value, the lower the oil pressure in oil passage 3)
.

The duty rate is controlled by a control unit C shown in FIG. Control unit) C: Signals from an engine throttle opening sensor (not shown), a vehicle speed sensor, an oil temperature sensor that measures the oil temperature in the oil passage 3, and a timer that measures the elapsed time after the engine starts. is man-powered. The control unit C includes an interface for receiving each of the above signals, a microcomputer consisting of a CPU, ROM, and RAM, an output interface, and a drive circuit for operating the solenoid winding 4a and, in turn, the electromagnetic solenoid 4. Said R.O.
The control program necessary for controlling the duty rate of the electromagnetic solenoid 4 is manually stored in advance in M, and the RAM is provided with various memories necessary to execute the above control, and the control program is manually stored in advance in accordance with each manual signal. , the duty rate of the electromagnetic solenoid 4 is controlled based on the control program.

The hydraulic pressure adjusted by the electromagnetic solenoid 4 is supplied as pilot pressure to the line pressure control valve 6 via an oil path 5.

The line pressure control valve 6 adjusts the line hydraulic pressure generated by the pump P to the optimal pressure for operating the friction elements of the automatic transmission in each running state, and is shown enlarged in FIG. 3. As shown, valve body 7 and spool 8
, a sleeve 9 interposed between the two, and an oil chamber 10 to
17 as the main parts. Note that the valve body 7 is arranged above the oil level of an oil reservoir (not shown).

The valve body 7 is formed with a spool hole 7a having a circular cross section, and a pilot oil passage 10 is provided in the spool hole 7a.
a1 first to third drain oil passages 11a, 13a, 15a,
Reverse oil passage 12a1 first and second line oil passages 14a,
16a and converter oil passage 17a are in communication with each other.

The outer periphery of the spool 8 and the inner periphery of the valve body 7 are cut to form an oil chamber at the communication portion of each oil passage to the spool hole 7a, and the pilot oil passage 10a is connected to the pilot oil chamber 10 and the oil passage. 5, the first to third drain oil passages 11a,'
13a, 15a are the first to third drain oil chambers 11.13.
15 and the oil pan of oil pump P, reverse oil path 1
2a connects the reverse oil chamber 12 and a reverse port of a manual valve (not shown), the first line oil passage 14a connects the line oil chamber 14 and the oil pump P, and the second line oil passage 16a connects the plane modifier oil chamber 16 and the oil pump. The converter oil passage 17a communicates with the converter oil chamber 17 and a torque converter (not shown). Further, an oil passage 19 leading to a friction element of the automatic transmission is connected to the first line oil passage 14a and the second line oil passage 16a.

The spool 8 is slidably inserted into a cylindrical sleeve 9 fitted into a spool hole 7a, and includes a first spool 8a to which pilot hydraulic pressure and reverse hydraulic pressure act, and a second spool 8b to which line hydraulic pressure acts. A spring 18 is compressed between the second spool 8b and a spring seat 9a provided on one end surface of the sleeve 9.

The sleeve 9 is connected to the valve body 7 and the spool 3 as described above.
As shown in FIG. 4, four communication holes 9b are bored in the radial direction near the communication portions of the respective oil passages. Further, the inner diameter of the sleeve 9 is slightly larger near the reverse oil chamber 12.

Each oil chamber 10.11.1 of the first spool 8a
As shown in FIG. 4, the oil chamber 2 is formed by constantly communicating an oil chamber formed on the outer periphery of the first spool 8a and the inner periphery of the valve body 7 through a communication hole 9b of the sleeve 9.

The line pressure control valve 6 configured in this manner operates as follows.

First, when the engine is stopped and no line pressure is applied, the second spool 8b is moved to the right in FIG. 3 by the urging force of the spring 18, so the outer peripheral surface 8C of the second spool 8b is It is in the position indicated by the chain line A in FIG. 3, and the converter oil passage 17a is closed.

Next, the engine is started, and the line pressure from the oil pump P driven by the engine is applied to the line oil passage 14a.
When the second spool 8b acts on the line oil chamber 14, the second spool 8b moves to the left against the urging force of the oil pressure in the pilot oil chamber 10, that is, the pilot oil pressure, and the spring 18, as shown by the solid line in FIG. position, converter oil passage 17a is opened to spool hole 7a, and converter oil pressure acts on the torque converter side.

As the accelerator opening degree increases, the engine speed and the pump speed increase and the line pressure increases, and the second sleeve 8b moves further to the left, causing the outer circumferential surface 8d of the second sleeve 8b to move along the chain line in FIG. B, the line oil passage 14a and the drain oil passage 1 are removed from the inner peripheral surface 7c of the valve body.
5a, a part of the oil is returned from the drain oil passage 15a to the oil pan, and the line pressure in the line oil chamber 14 and the converter oil chamber 17 is equal to the pilot oil pressure in the pilot oil chamber 10. The hydraulic pressure is stabilized at a constant level at a position balanced with the urging force of the spring 18 and the spring 18.

Therefore, by controlling the duty rate of the electromagnetic solenoid 4,
Hydraulic pressure in the oil passage 3 and therefore from the oil passage 5 to the pilot oil passage 10
By controlling the pilot oil pressure that acts on the pilot oil chamber 10 through step a, the urging force that urges the second sleeve 8b to the right, that is, the urging force caused by the pilot oil pressure and the spring 18, is controlled. , the line pressure to balance the biasing force is controlled. In other words, by controlling the duty rate of the electromagnetic solenoid 4, the line pressure supplied to the friction elements of the automatic transmission via the oil passage 19 is controlled.

Next, an example of the duty rate control routine for the electromagnetic solenoid 4 of the automatic transmission hydraulic control system according to the present embodiment configured as described above will be explained based on the flowchart shown in FIG.

In the figure, 81 to S7 indicate each control step. Control starts when the ignition key is turned ON, and first the control unit (C) outputs the throttle opening signal eL.
Read h and vehicle speed signal ■ (Sl), throttle opening e
Based on Lh and vehicle speed ■, line pressure PL is set according to a line pressure setting map stored in ROM in advance (
S2).

Next, the timer signal TM and oil temperature signal TP are read (S3), and it is determined whether the elapsed time TM after the engine start exceeds a predetermined time TX (S4). If TM is less than TX, the control unit C determines that air is mixed in the oil passage 3 and enters a correction duty rate setting routine. In other words, the correlation between the duty rate DTP of the electromagnetic solenoid 4 and the line pressure PL is such that the amount of air mixed in the oil passage 3 (if the amount of air mixed in is large, air, which is a compressible fluid, contracts), In this case, the pilot oil pressure becomes lower than when the amount of air mixed in is small, and the line pressure PL becomes lower), and the oil temperature TP in the oil passage 3 (when the oil temperature is high, the viscosity of the oil decreases, Under the same duty rate DTP, a larger amount of oil in the oil passage 3 is discharged to the oil pan via the drain oil passage 4d of the electromagnetic solenoid 4 than when the oil temperature is low. Considering that the amount of air mixed in the oil passage 3 depends on the elapsed time TM after the engine start, the elapsed time TM after the engine start RO is set in advance based on the oil temperature TP in the oil passage 3 and the set line pressure PL at that time.
Correlation map of line pressure PL and duty rate DTP (DTP=f(PL,
The duty rate DTP corresponding to the set line pressure PL is determined from TM,, TP) (S5). If TM is greater than or equal to TX, it is determined that there is no air mixed in the oil passage 3, and a normal duty rate setting routine is entered. That is, considering that the correlation between the duty rate of the electromagnetic solenoid 4 and the line pressure is influenced by the oil temperature TP in the oil passage 3, as described above,
Based on the set line pressure PL, the line pressure PL and duty rate DT are stored in the ROM in advance and are illustrated in Fig. 6.
From the correlation map of P (DTP=g(PL, TP)), the death rate DTP corresponding to the set line pressure PL is determined (S6). Next, the control unit C operates a drive circuit that energizes the electromagnetic solenoid 4 to control the duty rate of the electromagnetic solenoid 4 to DTP (S7).

After the above, the process returns to S1 and the operations from S1 onwards are repeated.

As can be seen from the above description, in the automatic transmission hydraulic control device according to the present embodiment, the duty rate of the electromagnetic solenoid 4 and the pilot oil pressure of the line pressure regulating valve 6 are maintained within a predetermined period of time after the engine is started. , the line pressure is set assuming that air is mixed into the oil passage 3, so the line pressure always satisfies the requirements.

Although the present invention has been described above with reference to one embodiment, it goes without saying that the present invention is not limited to this embodiment, and that various other modifications can be made within the scope of the present invention. For example, in the above embodiment, during the predetermined time period of the engine starter, the duty rate is controlled by the time after starting and the oil temperature, but in addition to this, the duty rate is controlled by the time from engine stop to restart. You can also do that.

(Effects of the Invention) According to the present invention, it is possible to prevent deviation of the pilot oil pressure from a predetermined value due to the mixing of air into the pilot oil pressure circuit, and it is possible to stabilize the control of the line pressure control valve and the control of the line pressure. A hydraulic control device for an automatic transmission is provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a hydraulic control device for an automatic transmission according to an embodiment of the present invention. 2 is an enlarged view of the electromagnetic solenoid 4 in FIG. 1, and FIG. 3 is an enlarged view of the line pressure control valve 6. FIG. 4 is a sectional view taken along the line ■-■ in FIG. 3. FIG. 5 is a flowchart showing an example of the control routine of the electromagnetic solenoid for the automatic transmission hydraulic control device according to the present embodiment. FIG. 6 is a correlation diagram between line pressure and electromagnetic pressure ratio. P...Pump 0 tatami 11 Control unit 4...Electromagnetic solenoid 6...Line pressure control valve 10...Pilot oil chamber 14a...Diameter of first line oil passage 4 Fig. 3 Fig. 4 Figure 6 Debt rate (DTP)

Claims (1)

[Claims] An electronically controlled automatic transmission in which hydraulic pressure is controlled by an electromagnetic solenoid, characterized by comprising means for correcting a control value for controlling the electromagnetic solenoid for a predetermined period of time after engine startup. Hydraulic control device for automatic transmission.