JP2002089680A - Line pressure control device of automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a line pressure control device of an automatic transmission capable of preventing slip in a friction element by suitably switching a common line pressure. SOLUTION: When a throttle opening TVO is lowered stepwise, engine torque Te is lowered to the static state region β of the engine torque Te through a decrease state region a of the engine torque Te. At that time, the line pressure PL is originally determined to be switched from high pressure PA to low pressure PB according to a Hi/Low determination map at a point of time t1 when the throttle opening TVO is less than a designated value. Actually, however, switching is started in the static state region β through the decrease region α, so that the line pressure PL is lowered from the high oil pressure PA to low oil pressure PB like a step. Thus, in switching the line pressure PL from high pressure PA to low pressure PB, the start of switching can be delayed for designated time after switching is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission in which a hydraulic pressure applied to a shift friction element is individually controlled in a shift control of an automatic transmission. The present invention relates to a device which is appropriately controlled.

[0002]

2. Description of the Related Art An automatic transmission determines a power transmission path (gear stage) of a gear transmission system by selectively hydraulically operating (engaging) a plurality of friction elements such as clutches and brakes.
A shift to another gear is performed by switching the friction element to be engaged. And the automatic transmission receives the engine rotation via the torque converter,
The input rotation is shifted at a gear ratio corresponding to the selected shift speed and output.

In the meantime, in the selective hydraulic operation (fastening) of the friction element, a so-called direct-acting-valve type automatic transmission in which each operating hydraulic pressure is individually controlled using a common line pressure as a base pressure has conventionally been used. For example, JP-A-7-33248
No. 0 has been proposed.

In this type of automatic transmission, the operating oil pressure of each friction element is individually controlled. Therefore, the line pressure, which is the source pressure of these operating oil pressures, should be engaged without being involved in a shock during shifting. Since it is only necessary to supply hydraulic pressure enough to secure the capacity required for the friction element to be engaged, compared to a system that supplies the friction element directly without adjusting the line pressure,
The need for fine-grained control is small.

Incidentally, the line pressure control technique described in the above-mentioned literature requires that the friction element for the reverse gear must transmit a larger torque than the friction element for the forward gear. When the gear is selected, the line pressure is made higher than when the forward gear is selected.

However, control for raising and lowering the line pressure during forward running is not performed, and only one type of line pressure control is performed during forward running. Therefore, when determining the line pressure, it is necessary to set the line pressure to a value that allows the friction element to reliably transmit the torque without slipping even when the maximum torque is input.

For this reason, a line pressure control device which can freely select a line pressure between a high pressure, a low pressure, and an arbitrary pressure in the middle is conventionally considered. In addition, a line pressure control device that can select and set two types of line pressure, high pressure and low pressure, so as to further simplify the control and the hardware device and not to change the effect so much is considered. Such a line pressure control device includes a control valve that determines a selected shift speed by causing a plurality of friction elements to be selected under the control of operating hydraulic pressures individually created from two types of line pressures, high pressure and low pressure. It is supplied to the gear stage control device provided as the original pressure.

A line pressure control device of an automatic transmission generally includes:
In order to detect more accurate engine torque, including transient characteristics, it is necessary to provide a means for detecting this and the result of the detection by the controller of the automatic transmission. Invites complications,
In addition, it leads to an increase in cost. For this reason, whether the common line pressure is set to a high pressure or a low pressure is determined by, for example, a preset map (hereinafter referred to as a Hi / Low determination map).
In some cases, it must be determined according to the conditions shown in.

This Hi / Low determination map is classified into two types of high pressure and low pressure based on the engine rotation or the turbine rotation which is the input side rotation of the automatic transmission and the throttle opening in order to know the state of the engine torque. For example, when a large fastening capacity is not required for the friction element, when the oil pressure balance in the automatic transmission is insufficient and the line pressure cannot be increased unnecessarily, or when the oil amount balance is insufficient. In cases such as preventing abnormal noise from occurring, it is set to switch the line pressure from high pressure to low pressure, and it is also necessary to prevent the fastened friction element from slipping due to a failure of the transmission unit or sensor, for example. Or increased capacity,
In addition, when the required capacity cannot be estimated because the engaged friction element does not slip, or when stabilizing the pressure regulation function of the friction element or the lock-up control valve, the line pressure is switched from low pressure to high pressure. It is set as follows.

[0010]

However, the above H
The i / Low determination map does not consider the transient state in which the engine torque is dynamically fluctuating. The i / Low determination map indicates the necessary capacity for preventing the engaged friction element from slipping according to the statically balanced engine torque state. Because it is created on the basis of, for example, a small amount of fuel is given to the engine when the accelerator pedal is released to prevent engine stall due to a sudden decrease in engine rotation, so-called transient dashpot In situations, for static engine torque,
It cannot respond to situations where the actual engine torque increases.

Therefore, there is no means for estimating the engine torque in consideration of the transient state of the engine, and the common line pressure is reduced by using the map created based on the state of the static engine torque. In the line pressure control device that switches between the two stages, the line pressure may not be properly switched with respect to the fluctuation of the engine torque, so that the friction element to be engaged may cause slippage. There is.

[0012] Figure 6 is a time chart showing a case in which can not be switched at an appropriate timing in a low oil pressure P _B to the line pressure P _L from the high pressure P _A, (a)
Is the throttle opening TVO, and (b) is the engine torque T
e, (c) shows the line pressure _{P L.}

As shown in FIG. 6A, the throttle opening T
When VO drops stepwise, the engine torque Te
As shown in FIG. 6 (b), the value falls through a region α in a transient state to a region β in a static state. In this case the line pressure _{P L} is determined at time t1 when the throttle opening TVO is equal to or less than a predetermined value, it is necessary to switch to the low oil pressure _{P B} to the line pressure _{P L} from the high pressure _{P A} from the Hi / Low determination map I do.

[0014] However, when the switching at time t1 is executed, the line pressure _{P L,} as shown in FIG. 6 (c),
Since the engine torque Te is held at a lower pressure P _B in the region α in a transient state, engagement capacity is insufficient in the portion of the region S of the engine torque Te shown in FIG. 6 (b), it should be entered There is a risk that the friction element will slip. The occurrence of such slippage not only causes a large shock when the slippage is settled and is re-engaged, even when the gear is not being shifted, but also significantly reduces the life of the friction material used for the friction element. I have to do it.

[0015] Incidentally, in the case of switching the line pressure P _L from the low pressure P _B in the high pressure P _A also, when the timing of the switching is delayed for variations in engine torque, friction elements should have concluded that slips Can be considered.

An object of the present invention is to provide a line pressure control device for an automatic transmission that can prevent slippage of a friction element by appropriately switching a common line pressure from a high pressure to a low pressure.

Another object of the present invention is to provide a line pressure control device for an automatic transmission which can prevent slippage of a friction element by appropriately switching a common line pressure from a low pressure to a high pressure. I do.

Still another object of the present invention is to provide a line pressure control device for an automatic transmission which can prevent slippage of a friction element by appropriately switching a common line pressure.

In addition, another object of the present invention is to provide a line pressure control device for an automatic transmission which can easily or reliably execute the timing of switching the line pressure from high pressure to low pressure. .

[0020]

To achieve these objects, a line pressure control device for an automatic transmission according to a first aspect of the present invention enables a common line pressure to be switched between high pressure and low pressure,
In an automatic transmission in which a selected shift stage is determined by selectively engaging a plurality of friction elements under control by operating hydraulic pressures individually created using the line pressure as a source pressure, the line pressure is reduced from a high pressure to a low pressure. When switching,
It is characterized in that the start of the switching is delayed for a predetermined time after the switching determination is made.

A line pressure control device for an automatic transmission according to a second aspect of the present invention enables a common line pressure to be switched between a high pressure and a low pressure in two stages, and controls the hydraulic pressure by using the line pressure as a source pressure. In an automatic transmission in which a selected gear is determined by selectively engaging a plurality of friction elements below, when switching the line pressure from low pressure to high pressure, immediately after the switching determination is made,
The line pressure is switched from a low pressure to a high pressure.

Further, the line pressure control device for an automatic transmission according to the third invention is capable of switching a common line pressure into two stages of a high pressure and a low pressure, and is controlled by an operating oil pressure which is individually generated using the line pressure as an original pressure. When the line pressure is switched from high pressure to low pressure in an automatic transmission in which the selected gear position is determined by selectively engaging a plurality of friction elements in the engagement operation, when the line pressure is switched from a high pressure to a low pressure, the line pressure is switched for a predetermined time after the switching determination is made. The switching start is delayed, and when the line pressure is switched from the low pressure to the high pressure, the line pressure is switched from the low pressure to the high pressure immediately after the switching determination is made. .

According to a fourth aspect of the present invention, in the automatic transmission line pressure control apparatus according to the first or third aspect, the predetermined time from when the line pressure is determined to be switched from the high pressure to the low pressure until the switching is started is: It is characterized by being measured by a timer.

According to a fifth aspect of the present invention, in the automatic transmission line pressure control apparatus according to the first or third aspect, the predetermined time from when the line pressure is determined to be switched from the high pressure to the low pressure until the switching is started is: The change in engine torque is estimated by a model of a predetermined delay system such as a first-order delay, and the estimated turbine torque calculated based on the engine torque taking the delay into account is the state when the line pressure switching determination is made. It is characterized by being measured when it becomes less than or equal to the turbine torque estimated value calculated based on the static engine torque estimated value corresponding to the above.

According to a sixth aspect of the present invention, in the automatic transmission line pressure control apparatus according to the first or the third aspect, the predetermined time from when the line pressure is determined to be switched from the high pressure to the low pressure until the switching is started may be: Turbine torque is estimated from the relationship between the characteristics of the torque converter and the engine rotation and turbine rotation, and the rate of change of the estimated value is a predetermined value with respect to the rate of change of the turbine torque estimated value calculated based on the static engine torque estimated value. Is measured when the ratio becomes

According to a seventh aspect of the present invention, in the automatic transmission line pressure control apparatus according to the first or third aspect, the predetermined time from when the line pressure is determined to be switched from the high pressure to the low pressure until the switching is started is: The method is characterized in that the speed ratio of the torque converter is measured, and is measured when the rate of change of the speed ratio of the torque converter becomes smaller than a predetermined value after the line pressure switching determination is made.

[0027]

The line pressure control device for an automatic transmission according to the first invention enables a common line pressure to be switched between a high pressure and a low pressure in two stages, and uses the line pressure as an original pressure to operate the hydraulic pressure individually generated. In an automatic transmission in which a selected gear is determined by selectively engaging a plurality of friction elements under control, when switching the line pressure from high pressure to low pressure, only a predetermined time after the switching determination is made, Since the start of the switching is delayed, the switching of the line pressure from the high pressure to the low pressure is performed at a timing when the engine torque becomes a static state after the transient change state of the torque at the time of the decrease of the engine torque ends. Done.
For this reason, it is possible to prevent slippage of the engaged friction element caused by the line pressure switching from high pressure to low pressure, which is caused by the transient change state of the torque when the engine torque decreases.

Therefore, according to the first aspect, the line pressure is switched from a high pressure to a low pressure at an appropriate timing while avoiding the influence of the transient change state of the engine to prevent slippage between the friction elements, thereby causing unpleasantness. Shock is avoided, and the life of the friction material used for the friction element is not shortened.

A line pressure control device for an automatic transmission according to a second aspect of the present invention enables a common line pressure to be switched between a high pressure and a low pressure in two stages, and is controlled by an operating hydraulic pressure which is individually generated using the line pressure as an original pressure. When the line pressure is switched from low pressure to high pressure in an automatic transmission in which the selected gear position is determined by selectively engaging a plurality of friction elements, the line pressure is reduced to low pressure immediately after the switching determination is made. Therefore, the line pressure is switched from the low pressure to the high pressure at a timing immediately after the increase of the engine torque is started. Therefore, it is possible to prevent the friction element from slipping due to switching from low pressure to high pressure after the line pressure is delayed with respect to the increase in engine torque.

Therefore, according to the second aspect, the line pressure is switched from low pressure to high pressure at an appropriate timing where the fluctuation of the engine torque is avoided to prevent slippage between the friction elements, thereby avoiding unpleasant shock. Further, the life of the friction material used for the friction element is not shortened.

A line pressure control device for an automatic transmission according to a third aspect of the present invention enables a common line pressure to be switched between two stages, a high pressure and a low pressure, and is controlled by an operating hydraulic pressure which is individually generated using the line pressure as a source pressure. When the line pressure is switched from high pressure to low pressure in an automatic transmission in which the selected shift speed is determined by selectively engaging a plurality of friction elements in the engagement operation, only a predetermined time after the switching determination is performed,
The start of the switching is delayed, and when the line pressure is switched from low pressure to high pressure, the line pressure is switched from low pressure to high pressure immediately after the switching determination is made.
It is possible to prevent both slippage caused by inappropriate timing of switching the line pressure from high pressure to low pressure and slippage caused by inappropriate timing of switching the line pressure from low pressure to high pressure.

Therefore, according to the third aspect of the present invention, unpleasant shock is avoided by preventing slippage between the friction elements caused by inappropriate timing of switching the line pressure with respect to the fluctuation of the engine torque. The life of the friction material used for the friction element is not shortened.

According to a fourth aspect of the present invention, in the automatic transmission line pressure control device according to the first or third aspect, the predetermined time from when a determination is made to switch the line pressure from a high pressure to a low pressure to when the switching is started is: It is measured by a timer. In this case, the start point of switching the line pressure from the high pressure to the low pressure can be easily delayed, which is advantageous in control.

According to a fifth aspect of the present invention, in the automatic transmission line pressure control device according to the first or the third aspect, the predetermined time from when the line pressure is determined to be switched from the high pressure to the low pressure until the switching is started is: The change in engine torque is estimated by a model of a predetermined delay system such as a first-order delay, and the estimated turbine torque calculated based on the engine torque taking the delay into account is the state when the line pressure switching determination is made. Is measured when the value becomes equal to or less than the turbine torque estimated value calculated based on the static engine torque estimated value corresponding to. In this case, it is possible to reliably start switching the line pressure from the high pressure to the low pressure.

According to a sixth aspect of the present invention, in the automatic transmission line pressure control device according to the first or the third aspect, the predetermined time from when a determination is made to switch the line pressure from a high pressure to a low pressure to when the switching is started is: Turbine torque is estimated from the relationship between the characteristics of the torque converter and the engine rotation and turbine rotation, and the rate of change of the estimated value is a predetermined value with respect to the rate of change of the turbine torque estimated value calculated based on the static engine torque estimated value. Therefore, the same operation and effect as those of the fifth aspect can be obtained.

The line pressure control device for an automatic transmission according to the seventh aspect of the present invention is the line pressure control device according to the first or third aspect, wherein the predetermined time from the determination of switching the line pressure from the high pressure to the low pressure to the start of the switching is: Since the speed ratio of the torque converter is measured and the rate of change of the speed ratio of the torque converter becomes smaller than a predetermined value after the line pressure switching determination is made, the fifth
The same operation and effect as the invention can be obtained.

[0037]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an automatic transmission provided with a line pressure control device according to an embodiment of the present invention, wherein 1 is an engine, and 2 is an automatic transmission. The output of the engine 1 is adjusted by a throttle valve that increases in opening degree from fully closed to fully opened as the accelerator pedal operated by the driver is depressed, and the output rotation of the engine 1 is transmitted through a torque converter 3 to an automatic transmission. 2 is input to the input shaft 4.

The automatic transmission 2 includes a front planetary gear set 6 and a rear planetary gear set 7 on the input / output shafts 4 and 5 arranged in a coaxial butting relationship from the engine 1 side.
Are mounted as main components of the planetary gear transmission mechanism in the automatic transmission 2. The front planetary gear set 6 close to the engine 1 is a simple planetary gear set including a front sun gear S _F , a front ring gear R _F , a front pinion P _F meshing with the front sun gear S _F , and a front carrier C _F rotatably supporting the front pinion. , Rear planetary gear set 7 far from engine 1
This is also a simple planetary gear set including a rear sun gear S _R , a rear ring gear R _R , a rear pinion P _R meshing with the rear sun gear S _R , and a rear carrier C _R rotatably supporting the rear pinion.

The low clutch L / C, the second speed and the low speed clutch are used as friction elements for determining the transmission path (gear position) of the planetary gear transmission mechanism.
4-speed brake 2-4 / B, high clutch H / C, low reverse brake LR / B, low one-way clutch L /
The OWC and the reverse clutch R / C are provided in correlation with the components of the two planetary gear sets 6 and 7 as described below. That is, the front sun gear S _F can be appropriately connected to the input shaft 4 by the reverse clutch R / C,
It can be appropriately fixed by the 2nd / 4th speed brake 2-4 / B.

Front carrier C_F Is high clutch H /
C makes it possible to appropriately connect to the input shaft 4. Front cap
Rear C_FIs also to Row One Way Clutch L / OWC
In addition to preventing rotation in the opposite direction to engine rotation,
-It can be appropriately fixed by the reverse brake LR / B.
You. And front carrier C_FAnd the rear ring gear R_R
Can be appropriately connected by a low clutch L / C.
You. Front ring gear R_FAnd rear carrier C_RBetween
The front ring gear R_FAnd re
Ya carrier C_RIs connected to the output shaft 6, and the rear sun gear S _RTo
It is connected to the input shaft 4.

The power transmission train of the planetary gear transmission mechanism includes friction elements L / C, 2-4 / B, H / C, LR / B, and R / C.
In FIG. 2, the selective hydraulic operation (fastening) indicated by a solid line 実
Due to the self-engagement of the low one-way clutch L / OWC indicated by a solid-line mark in the figure, the first forward speed (1st), the second forward speed (2nd), the third forward speed (3rd), and the fourth forward speed (4t
h) a forward gear and a reverse gear (Rev) can be obtained. Hydraulic operation (fastening) indicated by a dotted line in Fig. 2
Is a friction element to be activated when engine braking is required.

The shift control friction elements L / C, 2 shown in FIG.
-4 / B, H / C, LR / B, R / C
The control valve body 8 includes a lock-up solenoid indicated by reference numeral 34 in FIG. 3, a line pressure solenoid 9, a low clutch solenoid 10, a 2-speed / 4-speed brake solenoid 11, The high clutch solenoid 12, the low reverse brake solenoid 13, and the like are inserted.

ON / OFF of the line pressure solenoid 9
Control (high and low switching of the line pressure P _L), and the low clutch solenoid 10, 2-speed, 4-speed brake solenoid 1
1. The duty control of the high clutch solenoid 12 and the low reverse brake solenoid 13 are respectively executed by the transmission controller 14, and therefore, the transmission controller 14 is provided with a throttle opening sensor 15 for detecting the throttle opening TVO of the engine 1. and the signal, turbine speed sensor 1 for detecting the turbine speed N _t is the output rotational speed of the torque converter 3 (transmission input rotational speed)
6 and the rotational speed N _O of the output shaft 5 of the automatic transmission 2.
, And a signal from an inhibitor switch 18 for detecting a selected range.

FIG. 3 is a diagram showing the periphery of the control valve body 8 of FIG. 1 in more detail, wherein reference numeral 20 denotes a line pressure oil passage, reference numeral 21 denotes a manual valve, and reference numeral 22 denotes a manual valve.
Is a D range pressure oil passage, reference numeral 23 is an R range oil passage, and a manual valve 21 is a valve that can be switched by a select operation. In the D range, the line pressure oil passage 20 and the D range pressure oil passage 22 are connected. Line pressure oil passage 2 in range
0 and the R range oil passage 23 are connected.

The reference numeral 24 denotes a pilot valve, reference numeral 25 denotes a pilot pressure oil passage, the pilot valve 24 reduces the pressure controls the line pressure P _L from the line pressure oil passage 20 at a constant pilot pressure.

Reference numeral 26 denotes a first hydraulic control valve provided with the low clutch solenoid 10 and a low clutch amplifier valve (not shown). The first hydraulic control valve regulates the D range pressure to the low clutch pressure, and reduces the low clutch pressure to the low clutch pressure. The oil is introduced from the oil passage 27 to the low clutch L / C.

Reference numeral 28 denotes a second hydraulic control valve having a high clutch solenoid 12 and a high clutch amplifier valve (not shown). The second hydraulic control valve regulates the D range pressure to a high clutch pressure. The oil is introduced from the oil passage 29 to the high clutch H / C.

Reference numeral 30 denotes a third hydraulic control valve having a 2nd / 4th speed brake solenoid 11 and a 2nd / 4th speed brake amplifier valve (not shown).
The pressure is adjusted to the fourth-speed brake pressure, and the second- and fourth-speed brake pressure is introduced from the second- and fourth-speed brake pressure oil passage 31 to the second- and fourth-speed brakes 2-4 / B.

Reference numeral 32 denotes a fourth hydraulic control valve provided with a low reverse brake solenoid 13 and a low reverse brake amplifier valve (not shown). The fourth hydraulic control valve regulates the line pressure to a low reverse brake pressure. It is introduced from the low reverse brake pressure oil passage 33 to the low reverse brake LR / B.

Reference numeral 34 denotes a duty-controlled lock-up solenoid, which controls engagement and release of a lock-up clutch (not shown) provided in the torque converter 3.

[0051] by the line pressure solenoid 9 is ON / OFF control, switch the line pressure _{P L} to the two stages of the high pressure _{P A} and the low pressure _{P B,} and supplies the one of the line pressure oil passage 20.

[0052] In other words, and the switching of the line pressure _{P L,} the first
The control of the fourth hydraulic control valve is performed by the transmission controller 14.
Done at

From FIG. 1 to FIG. 3, the automatic transmission operation in the D range will be described. The transmission controller 14 executes a control program (not shown) to execute the throttle opening TVO based on a predetermined transmission map. And transmission output speed N
_{From O} (vehicle speed), a suitable gear position required in the current driving state is searched. Next, the transmission controller 14
Is to determine whether the currently selected current gear is equal to the preferred gear, and if the current gear is not the same, a shift command is issued to execute the shift to the preferred gear, that is, the engagement logic table of FIG. On the basis of this, the operating oil pressure of the friction element is changed by duty control of the solenoids 10 to 13 so that engagement and release switching of the friction element for the speed change is performed.

FIG. 4 is a flowchart for controlling the line pressure control device for an automatic transmission according to the present invention. Hereinafter, the present embodiment will be described in detail with reference to FIG.

[0055] The flowchart of FIG. 4, the transmission controller 14, there is executed a preset repeatedly every predetermined time in accordance with the control cycle, first, at step 110, the current line pressure P _L is pressure P _A
Is determined. In this step 110,
When the line pressure _{P L} is determined as a high pressure _{P A,} as the line pressure _{P L} is likely to switch to the low pressure _{P B} from the high pressure _{P A,} the process proceeds to step 120, the line pressure _{P L} is pressure _{P A} not equal it is determined, the line pressure _{P L} is the low pressure _{P B}
Then, the process proceeds to step 170 described later.

[0056] At step 120, the Hi / Low determination map described in the prior art, line pressure _{P L} pressure _{P A}
Determines whether the Hi → Low conditions for switching to the low-pressure _{P B} from. In this step 120, from the above map,
Hi line pressure _{P L} is switched to the low pressure _{P B} from the high pressure _{P A}
→ If it is determined that meets the Low condition, as the line pressure _{P L} is switched from the high pressure _{P A} to the low pressure _{P B,} the process proceeds to step 130.

However, at step 120, Hi → Low
If it is determined that the condition is not satisfied, step 160
Then, at step 160, the line pressure P_LThe high
Pressure P _AAfter commanding to hold the
Call this flowchart again after a predetermined time
Then, the present control is continuously performed.

In step 130, the count value T for measuring the delay time Δt is updated to the latest count value T _(new) by incrementing the previous count value T _(old) by (+1). Transition. However, the initial value of the count value T is T = 0, and the latest count value at the start of control is T _(ne
w) = 1.

In step 140, it is determined whether or not the updated count value T _(new) has exceeded a predetermined count value Tm. The predetermined count value Tm is a value that is equal to or longer than the time during which the transient state of the engine torque Te is always completed.

If it is determined in step 140 that the updated count value T _(new) has exceeded the predetermined value Tm,
The process proceeds to step 150, and in this step 150,
As has elapsed since the pressure P _A of the line pressure P _L is made to switch the determination on the low pressure P _B for a predetermined time Delta] t, switches the line pressure P _L from the high pressure P _A to the low pressure P _B. However,
At step 140, the updated count value T
If _(new) is determined not to exceed a predetermined value Tm, in step 160, after the line pressure P _L to command to hold the pressure P _A, the left ends, the flow again after a predetermined time This control is continued by calling.

That is, the flow up to steps 110 to 160
According to Low, the line pressure P_LThe high pressure P_AFrom low pressure P_BTo
When there is no need to switch, the line pressure P_LThe high pressure P_A
And keep the line pressure P_LThe high pressure P_AFrom low pressure P_BTo
When switching, wait for the switch
For a fixed time Δt, the line pressure P_LThe high pressure P_AFrom low pressure P _B
Delay the start of switching.

[0062] In this case, by using the timer of the line pressure P _L as a first means for delaying the start of the switching to the low pressure P _B from the high pressure P _A, by the timer, the line pressure P
_A predetermined time Δt from the determination of switching _L to the low pressure P _B from the high pressure P _A to the start of the switching is measured. In this case, since it is possible to easily delayed switching start of the line pressure P _L, which is the control advantageous.

[0063] Incidentally, the low-pressure P of the line pressure _{P L} from the high pressure _{P A
The} means for delaying the start of switching to _B is not limited to the means based on the timer detection, but may be any of steps 110 to 1.
The program up to 60 can be changed in various ways.

Specifically, there are means described below.

As the second means, the engine torque Te
Is estimated using an appropriate delay system model such as a first-order delay,
The torque calculated based on the engine torque considering the delay
Estimated value T of bin torque_AIs the line pressure P_LSwitching format
Static engine torque according to the state at the time the setting was made
Turbine estimated value T calculated based on the estimated value Te _B
If below, the line pressure P_LThe high pressure P_AFrom low pressure P_B
There is one that starts switching. In this case, the line pressure
P_LHigh pressure P_AFrom low pressure P_BStart switching to
Can be performed.

As a third means, the turbine torque is estimated from the characteristics of the torque converter and the relationship between the engine rotation and the turbine rotation, and the rate of change of the estimated value is based on the static estimated engine torque Te (x). Once reached a predetermined percentage of the calculated rate of change of the turbine torque estimate, a transient state in the change of the engine torque is considered to have ended, the start of switching the line pressure P _L from the high pressure P _a to the low pressure P _B There is something to do. In this case, it is possible to second similar means, performing the high pressure P _A of the line pressure P _L to reliably switching start to the low pressure P _B. Note that the estimated value Te (x) of the engine torque is Te (x) = torque capacity coefficient × (engine rotation) ² (1).

[0067] As a fourth means, to measure the speed ratio of the torque converter, when the speed ratio of the rate of change of the torque converter from being made to switch the determination of the line pressure P _L becomes smaller than the predetermined value, the engine torque transients T is considered to have ended, the line pressure P _L from the high pressure P _a is intended to initiate the switching to the low pressure P _B. In this case, as in the second means, the low pressure P from the high pressure P _A of the line pressure P _L
Switching to _B can be started reliably.

In particular, the flow up to steps 110 to 150
Is the line pressure P_LThe high pressure P_AFrom low pressure P_BSwitch to
When the switching determination is made, a predetermined time Δ
Since the start of this switching is delayed by t, the line
Pressure P_LHigh pressure P_AFrom low pressure P _BSwitching to the engine
Excessive change in torque when torque Te decreases
After the end of the state, the engine torque Te becomes a static state.
It is performed at the right timing. Therefore, the engine torque
Due to transient state of torque change when Te decreases
The line pressure P_LIs high pressure P_AFrom low pressure P_BSwitched to
Fastening elements resulting from the
Latch L / C, High clutch H / C, 2-speed / 4-speed brake
Key 2-4B, low reverse brake LR / B, reverse
Slip of at least one friction element of the clutch R / C
Can be prevented.

[0069] Therefore, according to the flow reaches step 110 to 150, the high pressure line pressure P _L at the right time the influence of the transient change state of the engine 1 is avoided P
By switching from _A to the low pressure P _B to prevent slippage between the friction elements, to avoid unpleasant shocks, also nor lowering the life of the friction material used in the friction element.

[0070] On the other hand, in step 110, the current line pressure _{P L} is determined whether the pressure _{P A} at the step 110, the line pressure _{P L} is determined not pressure _{P A,} the line line pressure P for pressure _{P L} is low _{P B
L} is as possibly switch from the low pressure _{P B} to the high pressure _{P A,} the process proceeds to step 170.

[0071] At step 170, from the Hi / Low determination map, and determines whether the line pressure _{P L} is Low → Hi condition for switching to the high pressure _{P A} from the low pressure _{P B.} In step 170, from the map, the line pressure _{P L} is determined as satisfying the Low → Hi condition for switching from the low pressure _{P B} to the high pressure _{P A,} the line pressure _{P L} to the high pressure _{P A} from the low pressure _{P B} Assuming that the switching is performed, the process proceeds to step 180. At step 180, the line pressure _{P L} is the low pressure _{P B}
Command to to switch to the high pressure P _A from.

However, at step 170, the Hi / L
from ow determination map, it is determined not to satisfy the Low → Hi condition, the process proceeds to step 190, at step 190, after the command to hold the line pressure P _L to the low pressure P _B, leave now Then, after a predetermined time, this flowchart is called again, and the control is continuously performed.

That is, steps 110, 170 to 190
According to the flow leading to the line pressure P _LTo low pressure P_BTo high
Pressure P_AWhen it is not necessary to switch to_LTo
Low pressure P_BAnd keep the line pressure P_LTo low pressure P_BTo high
Pressure P_AWhen switching to the friction element that should be
In order to prevent slipping, the switching determination in step 170 is
Immediately after the line pressure P_LTo low pressure P_BFrom high pressure P_ATo
Switch.

[0074] In particular, the flow reaches step 110,170,180, when switching the line pressure _{P L} from the low pressure _{P B} to the high pressure _{P A,} the friction element should have concluded, for example, low clutch L / C, high Clutch H / C, 2nd speed
4-speed brake 2-4B, low reverse brake LR /
B, so that at least one friction element of the reverse clutch R / C is not slipping, immediately after the switching decision is made, because switching the line pressure P _L from the low pressure P _B to the high pressure P _A, the line pressure P _L switching to the high pressure P _a from the low pressure P _B of is performed at timing immediately after the increase of the engine torque Te is started. Therefore, the low clutch L / C is a friction element the line pressure P _L is delayed with an increase in the engine torque Te from the low pressure P _B can occur by switching to a high pressure P _A, the high clutch H / C, the 2
Speed / four-speed brake 2-4B, low reverse brake LR
/ B and slippage in the reverse clutch R / C can be prevented.

[0075] Therefore, according to the flow reaching step 110,170～190, switched to the high pressure _{P A} at the right time the influence of the transient change state of the engine torque Te is avoided the line pressure _{P L} from the low pressure _{P B} By preventing slippage between the friction elements, an unpleasant shock is avoided, and the life of the friction material used for the friction elements is not shortened.

FIG. 5 shows the line pressure P _L of the present embodiment.
Is a time chart showing a case where the pressure is switched from a high oil pressure P _A to a low oil pressure P _B at an appropriate timing.
Is the throttle opening TVO, and (b) is the engine torque T
e, (c) shows the line pressure _{P L.}

As shown in FIG. 5A, the throttle opening T
When VO drops stepwise, the engine torque Te
Goes down through the region α in the transient state to the region β in the static state as shown in FIG. 5B. Originally this time the line pressure _{P L,} at time t1 when the throttle opening TVO is equal to or less than a predetermined value, described in the prior art have Hi / Low
On the determination map, it is determined that the condition is satisfied for switching the line pressure P _L from the high pressure P _A in the lower pressure P _B.

[0078] However Bagara, the present embodiment, the switching at a predetermined time after the determination time point t1 Delta] t time t2 has elapsed by the line pressure P _L high pressure P lower from _A hydraulic P _B
By executing the switching to the line pressure P _L is
As shown in FIG. 5 (c), decreases from a high pressure P _A in the region β engine torque Te is in a static state through the region α is a decreasing state of the engine torque Te to stepwise lower pressure P _B.

[0079] Accordingly, in this embodiment, as shown in the time chart of FIG. 5, when switching the line pressure P _L from the high pressure P _A to the low pressure P _B, a predetermined time Δt since been made the switching determination, of the switching by delaying the start, switching of the line pressure P _L is performed at the timing when the engine torque Te after transient change state of the torque at the time of reduction of the engine torque Te is completed becomes static state You can see that there is.

As is apparent from the above description, the present embodiment
State, the common line pressure P_LThe high pressure P_AAnd low pressure P_BNo
The line pressure P_LWith the original pressure
From individual hydraulic control valves 26, 28, 30, 32
Under the control of the operating hydraulic pressure
Clutch L / C, High clutch H / C, 2nd / 4th speed shake
2-4B, low reverse brake LR / B, river
By selectively engaging the scratch R / C
In automatic transmissions where the selected gear is determined, the line pressure
P_LThe high pressure P_AFrom low pressure P_BWhen switching to
This switching is performed only for a predetermined time after the switching judgment is made.
Delay of the start of _LTo low pressure P_BOr
High pressure P_AWhen switching to
Immediately after the line pressure P_LTo low pressure P_BFrom high pressure P_ATo
Since switching, the line pressure P_LThe high pressure P_AFrom low pressure P_B
Slippage caused by the timing of switching to
In pressure P_LTo low pressure P_BFrom high pressure P_ASwitch to taimi
To prevent slippage caused by delaying
it can.

Therefore, according to the present invention, the engine torque T
by preventing sliding between the friction elements caused by the timing of switching the line pressure P _L with respect to variations of e is delayed to avoid unpleasant shocks, also, the life of the friction material used in the friction element There is no drop.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing a transmission train of an automatic transmission having a line pressure control device according to an embodiment of the present invention, and a shift control system thereof.

FIG. 2 is a diagram showing a relationship between a selected shift speed of the automatic transmission and engagement logic of a friction element.

FIG. 3 is a schematic system diagram showing in detail a periphery of a control valve body 8 of FIG. 1;

FIG. 4 is a flowchart for controlling a line pressure control device for an automatic transmission according to the present invention.

[5] Of this embodiment, a time chart showing a case where the switch at the right time to lower the hydraulic pressure P _B to the line pressure P _L from the high pressure P _A, (a) is a throttle opening TVO, ( b) shows the engine torque Te, the (c) the line pressure _{P L.}

FIG. 6 shows a line pressure P of a conventional line pressure control device.
_L and a time chart showing a case in which can not be switched at an appropriate timing in a low oil pressure P _B from the high pressure P _A, (a) is a throttle opening TVO, (b)
Represents engine torque Te, the (c) the line pressure _{P L.}

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Automatic transmission 3 Torque converter 4 Input shaft 5 Output shaft 6 Front planetary gear set 7 Rear planetary gear set 8 Control valve 9 Line pressure solenoid 10 Low clutch solenoid 11 2nd / 4th speed brake solenoid 12 High clutch solenoid 13 Low reverse brake Solenoid 14 Transmission controller 15 Throttle opening sensor 16 Turbine rotation sensor 17 Output rotation sensor 18 Inhibitor switch 20 Line pressure oil passage 21 Manual valve 22 D range pressure oil passage 23 R range oil passage 24 Pilot valve 25 Pilot pressure oil passage 26 1 hydraulic control valve 27 low clutch pressure oil passage 28 second hydraulic control valve 29 high clutch pressure oil passage 30 third hydraulic control valve 31 2nd / fourth brake pressure oil passage 32 fourth hydraulic control valve 33 low Reverse brake pressure oil passage 34 Lock-up solenoid L / C Low clutch 2-4 / B 2nd / 4th speed brake H / C High clutch LR / B Low reverse brake R / C Reverse clutch L / OWC Low one way clutch

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J552 MA02 MA12 NA01 NB01 PA02 PA55 RA02 SA07 SA53 TB03 TB07 TB12 VA07W VA32Z VA34W VA42W VA53W VA62Z VA74W VA76W VB01Z VB18Z VC01W VC02W VC03Z VC06Z VD05Z

Claims (7)

[Claims] 1. A method in which a common line pressure can be switched between a high pressure and a low pressure in two stages, and a plurality of friction elements are selectively engaged under control by operating hydraulic pressures individually generated using the line pressure as a base pressure. In the automatic transmission in which the selected gear stage is determined by, when switching the line pressure from high pressure to low pressure, the start of the switching is delayed by a predetermined time after the switching determination is made, characterized in that Automatic transmission line pressure control device. 2. A method in which a common line pressure can be switched between a high pressure and a low pressure in two stages, and a plurality of friction elements are selectively engaged under control by operating hydraulic pressures individually generated using the line pressure as an original pressure. In the automatic transmission in which the selected shift speed is determined, when switching the line pressure from low pressure to high pressure, immediately after the switching determination is made, the line pressure is switched from low pressure to high pressure. Automatic transmission line pressure control device. 3. A method in which a common line pressure can be switched between a high pressure and a low pressure in two stages, and a plurality of friction elements are selectively engaged under control by operating hydraulic pressures individually generated using the line pressure as an original pressure. When the line pressure is switched from high pressure to low pressure, the start of the switching is delayed for a predetermined time after the switching determination is made, and the line pressure is A line pressure control device for an automatic transmission, wherein when switching from low pressure to high pressure, the line pressure is switched from low pressure to high pressure immediately after the switching determination is made. 4. The automatic transmission according to claim 1, wherein the predetermined time from when it is determined that the line pressure is switched from the high pressure to the low pressure to when the switching is started is measured by a timer. Line pressure control device. 5. A method according to claim 1, wherein the predetermined time from the determination of switching the line pressure from the high pressure to the low pressure to the start of the switching is obtained by estimating a change in engine torque using a model of a predetermined delay system such as a first-order delay. The estimated value of the turbine torque calculated based on the engine torque in consideration of the delay is equal to or less than the estimated value of the turbine torque calculated based on the estimated value of the static engine torque according to the state when the line pressure switching determination is made. 4. The line pressure control device for an automatic transmission according to claim 1, wherein the line pressure is measured by the following conditions. 6. The predetermined time from when the line pressure is switched from the high pressure to the low pressure until the start of the switching is determined by estimating the turbine torque from the characteristics of the torque converter and the relationship between the engine rotation and the turbine rotation. 4. The method according to claim 1, wherein the rate of change of the value is measured when the rate of change of the turbine torque estimated value calculated based on the estimated value of the static engine torque reaches a predetermined rate. A line pressure control device for an automatic transmission according to any one of the preceding claims. 7. The method according to claim 1, wherein the predetermined period of time from when a determination is made to switch the line pressure from a high pressure to a low pressure to when the switching is started is to measure the speed ratio of the torque converter, and after the determination is made to switch the line pressure, 4. The line pressure control device for an automatic transmission according to claim 1, wherein the change is measured when the rate of change of the speed ratio becomes smaller than a predetermined value.