JPH0454364A - Hydraulic control device of automatic transmission - Google Patents

Abstract

PURPOSE:To set up speed change feeling appropriately by providing a line pressure control means which controls the line pressure to be supplied to a hydraulic actuator means to be higher when the friction coefficient of the friction material is below the preset value, than the line pressure when the friction coefficient of the friction material is larger than the preset value. CONSTITUTION:In a control unit 70, various signals from a car speed sensor 62, a throttle opening indicator 54 and a traveling distance integrating meter 66 are read when the control is started together with the start-up of an engine. Then, a speed change stage is calculated based on the present car speed, and the maps of the throttle opening and speed change characteristics. Judgement is made on whether a speed change is achieved or not by comparing the presently-set speed change stage stored in the RAM memory with the speed change stage obtained from the above-mentioned calculation. If YES, another judgement is made whether total traveling distance is below 1000km or not. If YES, the line pressure map A for the speed change stage as calculated above is selected. If NO, the line pressure map B for the speed change stage as calculated above is selected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic control device for an automatic transmission, and in particular to one that controls line pressure in relation to the friction coefficient of the friction material of a friction engagement mechanism. Regarding.

[Prior art]

Automobile automatic transmissions include a speed change gear mechanism, multiple multi-disc clutch mechanisms and brake mechanisms as friction engagement mechanisms,
A hydraulic cylinder that connects and drives each of them, a hydraulic supply device (hydraulic pump, multiple control valves, and oil passages) that supplies line pressure to these hydraulic cylinders, and a hydraulic cylinder that uses the line pressure to adjust the throttle opening and the speed of the transmission gear mechanism. A line pressure control mechanism and the like are provided to control the pressure according to predetermined characteristics in association with the pressure.

Conventionally, as a predetermined characteristic for controlling the line pressure by the line pressure control mechanism, for example, the seventh
The characteristics shown in map B in the figure are adopted.

By the way, during the break-in period when a new vehicle has been driven for about 11,000 km or less after it has been used, the friction material of the friction fastening mechanism is generally not sufficiently familiar with the other member, so W! The coefficient of friction of friction materials tends to be relatively small.

Furthermore, Japanese Patent Application Laid-Open No. 62-220752 states that during break-in operation when the total operating time of the engine is less than a predetermined value, the shift timing or gear ratio is shifted in the direction of decreasing the average engine speed, and the cylinder A shift control device for an automatic transmission for a vehicle is described that prevents uneven wear of sliding parts.

[Problem to be solved by the invention]

As mentioned above, although the friction coefficient of the friction material of the friction engagement mechanism is relatively small during break-in, conventional automatic transmissions maintain the same line pressure during break-in and thereafter. However, during break-in operation, the engagement force of the friction engagement mechanism becomes smaller than the desired engagement force, causing problems such as deterioration of shift feeling. It had been.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic control device for an automatic transmission that can appropriately set a shift feeling despite changes in the friction coefficient of a friction material over time.

[Means to solve the problem]

A hydraulic control device for an automatic transmission according to a first aspect includes a friction engagement mechanism, a hydraulic actuator means for engaging and driving the friction engagement mechanism, and a hydraulic pressure supply device for supplying line pressure to the hydraulic actuator means. In the automatic transmission, a detection means for directly or indirectly detecting a change in the friction coefficient of the friction material of the friction engagement mechanism; and line pressure control means for controlling the line pressure supplied to the hydraulic actuator means to be higher than when the friction coefficient is greater than a predetermined value.

A hydraulic control device for an automatic transmission according to a second aspect of the present invention is such that in the hydraulic control device for an automatic transmission according to the first aspect, the detection means comprises a mileage accumulating means for accumulating the mileage of the automobile, and The pressure control means is configured to set and keep the line pressure higher than normal characteristics when the traveling distance is less than a predetermined value, and to set the line pressure with normal characteristics after the traveling distance becomes greater than the predetermined value. This is what is being done.

[Effect]

In the hydraulic control device for an automatic transmission according to the first aspect, basically, when line pressure is supplied from the line pressure supply means to the hydraulic actuator means, the friction engagement mechanism is driven to engage by the hydraulic actuator means.

Here, the detection means directly or indirectly detects a change in the friction coefficient of the friction material of the friction engagement mechanism. In response to the output of the detection means, the line pressure control means controls the line pressure supplied to the hydraulic actuator means to be higher when the friction coefficient of the friction material is less than a predetermined value than when the friction coefficient is greater than a predetermined value.

Therefore, even when the friction coefficient is less than a predetermined value, it is possible to suppress a decrease in the engagement force of the friction engagement mechanism and control the engagement force to have a predetermined characteristic, and it is possible to appropriately set the shift feeling. I can do it.

In the hydraulic control device for an automatic transmission according to a second aspect of the present invention, the detection means comprises a mileage accumulating means, and the line pressure control means adjusts the line pressure to a normal characteristic (this (the throttle opening degree is set as a parameter for each gear stage), and the line pressure is set to a normal characteristic after the travel distance becomes greater than a predetermined value.

Therefore, even during break-in operation until the friction material of the friction engagement mechanism gets used (the friction coefficient of the friction material is relatively small), it is possible to generate a fastening force with predetermined characteristics and set the shift feeling appropriately. .

〔Effect of the invention〕

According to the hydraulic control device for an automatic transmission according to the first claim,
As explained in the [Operation] section above, the line pressure is controlled so that the reduction in fastening force is suppressed when the friction coefficient of the friction material of the friction fastening mechanism is less than a predetermined value, and the fastening force has predetermined characteristics. It is possible to set the shift feeling appropriately.

According to the hydraulic control device for an automatic transmission according to the second claim,
As explained in the [Function] section above, the line pressure can be controlled so that the tightening force has the predetermined characteristics even during break-in when the mileage is less than a predetermined value, and the shift feeling can be appropriately set. You can.

〔Example〕

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

This embodiment is an example in which the present invention is applied to a hydraulic automatic transmission for an automobile.

As shown in FIG. 1, the automatic transmission 60 changes the speed of the rotation of the crankshaft of the engine 50 and outputs the same to an output shaft 61 (drive shaft).

A throttle valve 53 is interposed in the intake passage leading from the air cleaner 51 of the engine 50 to the intake manifold 52, and a throttle opening sensor 54 is provided to detect the opening of the throttle valve 53, and outputs an output in conjunction with the output shaft 61. A vehicle speed sensor 62 is provided to detect the rotation angle of the shaft 61.

A torque converter 63 is provided at the front of the automatic transmission 60, and rotation of the crankshaft is transmitted to the turbine shaft of the automatic transmission 60 via the torque converter. automatic transmission 6
0 has a general configuration that includes a planetary gear type transmission mechanism in addition to a torque converter 63, and the automatic transmission 60 is provided with a hydraulic pump and a control valve unit 64 built into the automatic transmission 60. The automatic transmission 60 incorporates a plurality of friction engagement mechanisms such as a multi-disc clutch of a planetary gear type transmission mechanism, a rotary up clutch of a brake and torque converter 63, and a hydraulic cylinder that engages and drives each of these friction engagement mechanisms. The control valve unit 64 is provided with a line pressure control mechanism that controls the line pressure supplied to the hydraulic cylinders, and a plurality of shift solenoid valves 65 that control the supply and discharge of line pressure to these hydraulic cylinders, respectively. .

Duty solenoid valve 1 of the above line pressure control mechanism
A control unit 70 is provided to control the speed change solenoid valve 65 and the signal from the throttle opening sensor 54, the signal from the vehicle speed sensor 62, and the distance traveled by the vehicle (mileage totalizer 66). A signal from the control unit 70 is supplied to the control unit 70.

Next, the line pressure control mechanism will be explained with reference to FIG. 2.

In FIG. 2, the hydraulic pressure generated by the pump P is reduced to a predetermined pressure by the pressure reducing valve 4 through the oil line 2, and this reduced oil pressure is supplied to the throttle modulator valve 8 via the oil line 6, and a portion of it is is duty solenoid valve 10
The pressure is supplied to the throttle modulator valve 8 as pilot pressure through a duty pressure passage 12 provided with the pressure.

This throttle modulator valve 8 is designed to generate a throttle modulator pressure according to the duty rate of the duty solenoid valve 10.

By controlling the on-time ratio (duty rate) per cycle of on-off operation in the duty solenoid valve 10, the working oil pressure (duty pressure) in the duty pressure passage 12 is adjusted (the higher the duty rate is, the more the duty rate is duty pressure will be lower).

The throttle modulator pressure generated by the throttle modulator valve 8 using the duty pressure adjusted according to the duty rate of the duty solenoid valve 10 as a pilot pressure is supplied as pilot pressure to the line pressure control valve 16 via the pilot pressure passage I4. It is now possible to do so.

An accumulator 44 is provided in the pilot straight path IM 14 between the throttle modulator valve 8 and the line pressure control valve 16 to absorb hydraulic pulsation when it occurs in the pilot pressure passage 14, and the line pressure control valve 16 It is designed to stabilize the pilot pressure supplied to the

Incidentally, the accumulator 44 is formed with a drain boat 46 and a discharge pressure boat 48, and also functions as a relief valve.

The line pressure control valve 16 adjusts the hydraulic pressure generated by the pump P to the optimum pressure for operating the hydraulic cylinder of the friction engagement mechanism of the automatic transmission at each gear stage, as shown in Fig. 3. The main parts include a valve body 18, a spool 20, a sleeve 22 interposed between the two, and oil chambers 24, 26, 28, 30, 32, 34, 36, and 38.

A spool hole 18a with a circular cross section is bored in the valve body 18, and the spool hole lea has a pilot pressure passage 14, a first, a second,
Third drain oil passages 26a, 30a, 34a, reverse oil passage 28a, first and second line oil passages 32a, 36a, and converter oil passage 38a are communicated with each other.

A spool 2 is provided at the communication portion of each wave path to the spool hole 18a.
The outer periphery of the valve body 18 and the inner periphery of the valve body 18 are cut to form an oil chamber, and the pilot pressure passage 14 connects the pilot oil chamber 24 and the output port of the spool modulator valve 8 to the first, second, and third drains. Oil passage 26a, 30a, 3
4a connects the first, second, and third drain oil chambers 26, 30, and 34 and the oil pan of the oil pump P, and the reverse oil passage 28a connects the reverse oil chamber 28 and the reverse port of a manual valve (not shown) to the first line oil. The passage 32a is the line oil chamber 32
and the oil pump P, the second line oil passage 36a communicates the pressure modifier oil chamber 36 and the oil pump P, and the converter oil passage 38a communicates the converter oil chamber 38 and the torque converter 63. The first line oil passage 32a and the second line oil passage 36a communicate with an oil passage 40 that leads to a hydraulic cylinder of a friction engagement mechanism of the automatic transmission.

The spool 20 is slidably inserted into a cylindrical sleeve 22 fitted into the spool hole 18a, and is comprised of a first spool 20a to which pilot pressure and reverse hydraulic pressure act, and a second spool 20b to which line pressure acts. A spring 42 is compressed between the second spool 20b and a spring seat 22a provided on one end surface of the sleeve 22.

Next, the operation of the line pressure control valve 16 and the like will be explained.

When the engine 50 is stopped and no line pressure is applied, the second spool 20b is moved to the right in FIG. 3 by the biasing force of the spring 42. In this case, the converter oil passage 38a is at the position indicated by the third chain line A, and the converter oil passage 38a is closed.

Next, the engine 50 is started, and the line pressure from the oil pump P driven by the engine 50 is applied to the line oil passage 32.
a to the line oil chamber 32, the second spool 20
b moves to the left against the hydraulic pressure in the pilot oil chamber 24, that is, the urging force of the pilot pressure and the spring 42, and reaches the position shown by the solid line in FIG.
A is opened to the spool hole 18a, and converter oil pressure acts on the torque converter side.

As the accelerator opening degree increases, the engine speed, that is, the pump speed increases, and the line pressure increases, and the second spool 20b further moves to the left.
The land portion 20d is at the position indicated by the chain line B in FIG. The line pressure is the pilot pressure in the pilot oil chamber 24 and the spring 42.
The oil pressure stabilizes at a constant level at a position that balances the biasing force caused by the pressure.

Therefore, the duty rate of the vertical solenoid valve 10 is controlled by the control unit 70, and the operating oil pressure (duty pressure) in the duty pressure passage and the spool modulator valve 8 are used to control the pilot. By controlling the pilot pressure that acts on the pilot oil chamber 24 through the pilot oil chamber 14, the urging force that urges the second spool 20b to the right (that is, the urging force of the pilot pressure and the spring 42) is controlled, and as a result, Line pressure is controlled to balance the biasing force. In other words, by controlling the duty rate of the duty solenoid valve 10, the line pressure supplied to the oil chamber cylinder of the friction engagement mechanism of the automatic transmission via the oil passage 40 is controlled.

Next, the control unit 70 will be explained.

The control unit 70 is for controlling the automatic transmission 60 via the control valve unit 64.
A microcomputer including a CPU, ROM, and RAM, an input/output interface, an A/D converter, a waveform shaping circuit, a drive circuit for the speed change solenoid valve 65, a drive circuit for the duty solenoid valve 10, etc. It is equipped with

The ROM of the microcomputer includes a vehicle speed sensor 6.
Based on the vehicle speed signal from 2 and the throttle opening signal from the throttle opening sensor 54, a shifting characteristic as shown in FIG. A control program and a control program for line pressure control that controls the line pressure supplied to the plurality of hydraulic cylinders of the friction engagement mechanism via the duty solenoid valve 10 are input and stored in advance.
Here, line pressure control unique to the present application will be explained.

For example, during the break-in operation in which a new automobile has been driven for only about 1000 kl+ after the start of use, the friction material of the friction engagement mechanism in the automatic transmission 60 is not sufficiently familiar with the sliding contact member of the other party, so the friction of the friction material The coefficient becomes smaller, and after the break-in period passes, the friction coefficient becomes larger and becomes stable.

Figure 6 shows the characteristics of this friction coefficient change over time.
During break-in when the total mileage is less than about 1,000 miles, the friction coefficient increases as the total mileage increases, and after the break-in period has elapsed, the friction coefficient becomes a constant larger value.

In order to prevent the engagement force of the friction engagement mechanism from fluctuating due to the change in the friction coefficient over time and to achieve an appropriate shift feeling during break-in and thereafter, the following steps are taken as shown in Figure 7. After the running period has elapsed, the line pressure is set in relation to the throttle opening as shown in the solid broken line map B, and during the break-in period, the line pressure is set higher than map B by approximately a predetermined value as shown in the dotted broken line. As shown in map A, it is set in relation to the throttle opening. However, the seventh
The figure shows the line pressure at the second gear, for example, and the line pressure map A-B is shown for each gear as shown in Figure 7.
shall be set.

A map of line pressure characteristics for all gears, as illustrated in FIG. 7, is stored in the ROM along with the line pressure control program.

On the other hand, there is a correlation between the duty rate and the duty pressure as shown in FIG. 4, and a map of this characteristic is also stored in the ROM along with the line pressure control program.

There is a predetermined correlation between the duty pressure, throttle modulator pressure, and line pressure, and this correlation is included in the line pressure control program.

Next, the automatic shift control and line pressure control routines described above will be explained based on the schematic flowchart of FIG. 8.

In the figure, Si (i=1.2, . . . ) indicates each step.

When the control starts with the start of the engine 50, the vehicle speed sensor 62, the throttle opening 54, and the mileage totalizer 66
Various signals are read in (S1), then the gear position is calculated based on the current vehicle speed and throttle opening and the map of the shift characteristics shown in Fig. 5 (S2), and then stored in the RAM memory. It is determined whether or not to shift by comparing the currently set gear position and the gear position obtained by the above calculation (33), and if YES, the total mileage is 1000 ky.
It is determined whether it is less than or equal to s (S4), and if No, Sl
Return to When the result of the determination in S4 is Yes, the line pressure map A for the gear position calculated above is selected (S5), and when the result is No, the line pressure map B for the gear position calculated above is selected (S6), and the next step is performed. Then, the duty rate is calculated using map A or map B and the map shown in FIG. 4 (S7), and then the driving pulse of the duty rate determined above is output to the solenoid of the duty solenoid valve 10 (S8). Next, a drive current is output to the shift solenoid valve 65 to set the gear position calculated above (
S9), returns to S1 from 39, and steps S1 and subsequent steps are repeatedly executed at minute intervals.

In the hydraulic control device for the automatic transmission described above, map A and map B are provided for each gear in the line pressure control control program, and during the break-in period, after the break-in period has elapsed. Since the line pressure is set higher than the above, it is possible to generate the same frictional engagement force as after the break-in period when the friction coefficient of the friction material of the friction engagement mechanism during the break-in period is relatively small. This makes it possible to prevent the shift feeling from deteriorating and provide an appropriate shift feeling.

It is also conceivable to control the line pressure to be higher than map A when the total travel distance is, for example, 500+s or less.

In this embodiment, the total traveling distance is used as a parameter for switching between map A and map B, but the total driving time or the number of gear changes, which has a certain correlation with the total traveling distance, may be used as a parameter.

Furthermore, the friction coefficient is indirectly detected by detecting the torque acting on the sliding member on which the friction material slides and the torque of the turbine shaft or output shaft 61 using a torque sensor or a strain gauge.
Map A may be used when the coefficient of friction is less than a predetermined value, and map B may be used when the coefficient of friction is greater than a predetermined value.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram of an automatic transmission installed in an engine and its hydraulic control device;
Fig. 2 is a configuration diagram of the line pressure control mechanism, Fig. 3 is an enlarged sectional view of the line pressure control valve, Fig. 4 is a diagram showing the relationship between duty ratio and duty pressure, Fig. 5 is a shift characteristic diagram, FIG. 6 is a characteristic diagram of the coefficient of friction of the friction material, FIG. 7 is a diagram showing a map of line pressure, and FIG. 8 is a schematic flowchart of a routine for automatic speed change control and line pressure control. 4...Pressure reducing valve, 8...Throttle modulator valve, 10...Duty solenoid valve,
16...Line pressure control valve, 60...Automatic gear shift m,
64... Control valve unit, 66... Mileage totalizer, 70... Control unit. Figure 1 Ill: Control unit Figure 2 Figure 4 Figure 5 Vehicle speed Figure 6 Figure 7 Throttle width

Claims (2)

[Claims] (1) In an automatic transmission comprising a friction engagement mechanism, a hydraulic actuator means for engaging and driving the friction engagement mechanism, and a hydraulic pressure supply device for supplying line pressure to the hydraulic actuator means, the friction material of the friction engagement mechanism is a detection means for directly or indirectly detecting a change in the friction coefficient of the friction material; 1. A hydraulic control device for an automatic transmission, comprising: line pressure control means for controlling high line pressure supplied to the means. (2) The detection means comprises a mileage accumulating means for accumulating the mileage of the automobile, and the line pressure control means sets the line pressure higher than normal characteristics when the mileage is less than a predetermined value. The hydraulic control device for an automatic transmission according to claim 1, wherein the line pressure is set to a normal characteristic after the travel distance exceeds a predetermined value.