JP2803489B2 - Transmission control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission which is used together with a device for preventing friction during overrun of a one-way clutch provided in a power transmission system of the automatic transmission.

[0002]

2. Description of the Related Art In an automatic transmission, a corresponding shift speed is selected by selectively hydraulically operating (engaging) various friction elements (friction clutch or friction brake), and a shift to another shift speed is performed by changing the operating friction element. Configure to do so.

In the upshift from the low gear to the high gear, power transmission at the low gear is performed via a one-way clutch so that the shift to the high gear is completed by overrun of the one-way clutch. This is preferable from the standpoint of gear shift shock, and many automatic transmissions adopt this method today.

[0004] The applicant of the present invention is developing and using “NISSA”.
N-Maxima New Model Manual Introduction to the Changes in J30 Series "1
The automatic transmission described in August 1999 (FOO7671) is no exception. In this automatic transmission, the forward one-way clutch corresponds to the one-way clutch, and the forward one-way clutch is a first one-way clutch.
The gears are engaged in the third to third speeds to contribute to power transmission, and in the third speed state, the shift to the fourth speed executed when the band brake is additionally operated is in an overrun state, so that the shift is smoothly performed. Can be performed.

However, at the fourth speed, the forward one-way clutch is still connected to the rotating members that rotate the inner and outer races separately from each other, so that the one-way clutch can be prevented from being subjected to the friction shock due to the relative rotation between the inner and outer races. However, the power loss is increased by that much, and the fuel efficiency is deteriorated.

In order to solve this problem, the applicant of the present application firstly
Japanese Patent Application No. 4-50734 proposes an automatic transmission in which a friction element (forward clutch) for selecting a low-speed gear related to a one-way clutch is not involved in power transmission at the fourth speed, so that it is released. It is.

[0007]

However, if measures are taken to open the friction element for selecting the low gear in such a high gear (fourth gear), the downshift to the low gear where this friction element should be engaged is performed. At the time of shift shifting, the cylinder capacity of the element is large because it is for a low-speed stage, and an accumulator is provided in the operating pressure circuit of the element to prevent shift shock, so the fastening of the element tends to be delayed, The following problems arise.

That is, in the automatic transmission according to the invention of the prior application,
In detail, from the fourth speed to the third speed as shown in FIG.
Instant t at which the downshift command is issued₁4th speed
Pressure P _FourDecreases, and then instantaneously t_TwoWith forward clutch
Pressure P_{F / C}Rise, but the forward clutch
Due to the reasons for the fastening delay, automatic change occurs momentarily during the shift.
Set the gearbox to neutral. By the way, downshifting is
Normally, power-on with the engine accelerator pedal depressed
At this time, the engine
As shown in FIG._ThreeDirectly
In front of the wind, not only the shift delay, but also the size accompanying the wind
Shift shock.

The present invention relates to an automatic transmission of the type described above,
A friction element for engine braking (an overrun clutch in the automatic transmission of the above-mentioned prior application) is provided in parallel with the one-way clutch and the friction element for selecting a low-speed gear (forward clutch) related thereto, and is engaged. Based on the fact that the friction element for engine braking has a small cylinder capacity and does not require an accumulator, it hardly causes a delay in engagement, This friction element (overrun clutch)
If the low-speed gear is to be released during the downshift, as shown in FIG. It is an object of the present invention to compensate and eliminate the above problems.

[0010]

SUMMARY OF THE INVENTION For this purpose, the present invention relates to a method for controlling the transmission of power through a one-way clutch by engaging a certain friction element, and selecting a low-speed gear in parallel with the certain friction element and the one-way clutch. It is possible to obtain engine braking at the low speed stage by engaging the friction element for engine brake arranged at the low speed stage, and when engaging the other friction element in the low speed stage selection state, the overrun of the one-way clutch causes the high speed stage to be overrun. In this automatic transmission, the friction of the one-way clutch can be prevented by releasing the engagement of the certain friction element in the high speed stage selected state. A downshift-shift detecting means for detecting a shift, and engaging the engine brake friction element during the shift detection. Characterized in structure in which a speed change lag compensation means for compensating the fastening delay friction element that.

[0011]

The automatic transmission is in a low speed stage selection state in which power is transmitted through a one-way clutch by engaging a certain friction element, but the engine brake is not effective in the low speed stage selection state due to power transmission through the one-way clutch. In a driving state in which engine braking is required, overrunning of the one-way clutch is disabled by fastening the friction element for engine braking provided in parallel with the certain friction element and the one-way clutch, and the engine brake at the low speed stage is stopped. Make it possible.

When another friction element is engaged in the low speed gear selection state, the automatic transmission is shifted to the high gear by the overrun of the one-way clutch. Then, by releasing the engagement of the certain friction element in the high-speed gear selection state, it is possible to prevent unnecessary friction of the one-way clutch from occurring at the gear.

The shift delay compensating means engages the friction element for engine braking while the downshift detecting means detects the shift from the high gear to the low gear. As a result, since the engine brake friction element is arranged in parallel with the certain friction element and the one-way clutch, and since the engine brake friction element does not cause a delay in engagement, the downshifting This compensates for the delay in the engagement of the certain friction element to be fastened during the shift, and can eliminate the shift delay, engine idling, and shift shock caused by the engagement delay.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a power transmission train of an automatic transmission to which the transmission control device of the present invention is applied and a fastening logic table of various friction elements. This transmission train is the same as that described in the literature,
An input shaft 2 to which rotational power from an engine crankshaft is transmitted via a torque converter 1 and an output shaft 3 coaxial with the input shaft 2, and a first planetary gear set 4 and a second planetary gear arranged coaxially on these input and output shafts. It is composed of a gear set 5 and various friction elements described later.

The first planetary gear set 4 is a normal simple planetary gear set including a sun gear 4S, a ring gear 4R, a pinion 4P meshing with the sun gear 4S, and a carrier 4C rotatably supporting the pinion 4P. Sun gear 5
S, a simple planetary gear set including a ring gear 5R, a pinion 5P, and a carrier 5C.

Next, various frictional elements that control the speed change control will be described. The carrier 4C can be appropriately connected to the input shaft 2 via the high clutch H / C, and the sun gear 4S can be appropriately fixed to the input shaft 2 by the reverse clutch R / C in addition to the sun gear 4S. I do. The carrier 4C can be further appropriately fixed by a multi-plate low reverse brake LR / B, and prevents reverse rotation (rotation in the opposite direction to the engine) via the low one-way clutch LO / C. The ring gear 4R is integrally connected to the carrier 5C and is drivingly connected to the output shaft 3, and connects the sun gear 5S to the input shaft 2. Ring gear 5R is overrun clutch OR / C
In addition to being able to be appropriately coupled to the carrier 4C via the, the carrier is correlated with the carrier 4C via the forward one-way clutch FO / C and the forward clutch F / C. Forward one-way clutch FO / C is forward clutch F
It is assumed that the ring gear 5R is coupled to the carrier 4C in the reverse rotation direction (the direction opposite to the engine rotation) in the coupling state of / C.

High clutch H / C, reverse clutch R
/ C, low reverse brake LR / B, overrun clutch OR / C and forward clutch F / C are respectively
The band brakes B / B are operated by supply of hydraulic pressure to perform the above-mentioned proper coupling and fixing. The second-speed servo apply chamber 2A, the third-speed servo release chamber 3R and the fourth-speed servo release chamber are particularly provided as shown in the table of FIG. It has a servo apply chamber 4A, which is opened in a normal state, fastened by supplying pressure only to the chamber 2A, opened when supplying pressure to the chamber 3R in addition to the chamber 2A, and opened to the chamber 4A in addition to the chambers 2A, 3R. It shall be tightened when supplying pressure.

The power transmission train shown in FIG. 1 includes friction elements B / B, H
/ C, F / C, OR / C, LR / B, and R / C are operated in various combinations as shown in the table of FIG. In conjunction with the appropriate operation (engagement) of C, the rotation state of the elements constituting the planetary gear sets 4 and 5 is changed, thereby changing the rotation speed ratio of the output shaft 3 to the rotation speed of the input shaft 2 and moving forward. A fourth reverse speed and a first reverse speed can be obtained. In the table of FIG. 1, the symbol “△” also indicates operation (inflow of hydraulic pressure), and the symbol “△” indicates a friction element to be activated when engine braking is required. And
While the overrun clutch OR / C is being actuated as indicated by the mark, the forward one-way clutch FO / C juxtaposed thereto is kept unreleased to enable engine braking, and the low reverse brake LR / B is actuated. Of course, the low one-way clutch LO / C juxtaposed therewith is kept unreleased to allow engine braking.

Further, the forward clutch F /
The dotted circle C in C indicates that the clutch has not been engaged in power transmission at the fourth speed, but has been conventionally engaged due to the shift control hydraulic circuit. In this case, at the fourth speed, the outer race of the forward one-way clutch FO / C is driven at the same speed as the input rotation, and there is a relative rotation between the inner race and the one-way clutch FO / C which is being rotated at an increased speed. The fuel efficiency is deteriorated due to the friction of / C.

Therefore, in this embodiment, the one-way clutch FO / C is deactivated (disengaged) by the drain of the operating pressure at the fourth speed.
The outer race can rotate following the inner race, preventing friction of the one-way clutch and improving fuel efficiency. To this end, a shift control hydraulic circuit for the power transmission train of FIG. 1 is configured as shown in FIG. However, this circuit is basically the same as the shift control hydraulic circuit described in the above-mentioned document, and FIG. 2 shows only a portion related to the present invention.

[0021] 11 in the regulator valve, by a well-known action of hydraulic oil from the oil pump 12 by regulating the predetermined line pressure P _L, outputs the same to the circuit 13 to be used as all of the original pressure of the automatic transmission I do. This line pressure is manual valve 14,
The pilot pressure is supplied to the pilot valve 15 and the switching valve 16, and the pilot valve 15 reduces the line pressure P _L to a constant pilot pressure P _P. This is controlled by a circuit 17 by a forward clutch control valve 18, shift solenoids A and B and over Supply to the run clutch solenoid C.

The manual valve 14 is manually operated according to the driving mode desired by the driver.
(N) When setting to the range, the line pressure of the circuit 13 is not supplied to any output circuit, but all are drained. Manual valve 14
Outputs the line pressure of the circuit 13 to the circuit 19 as the D range pressure P _D when the automatic transmission is to be shifted to the D range, drains all the other output circuits, and requests the second speed engine braking. The line pressure of circuit 13 to circuit 20
Is output as a two-range pressure P ₂ , the other output circuit is drained, and the line pressure of the circuit 13 is also applied to the circuit 21 as one range pressure P ₁ when the first speed engine brake is desired to be in one range.
And the other output circuit is drained.
Further, the manual valve 14 outputs the line pressure of the circuit 13 as the R range pressure to the circuit 22 when the reverse range is desired and the R range is set, and drains all other output circuits.

On the other hand, the D range pressure circuit 19
Switch control valve 18, which is connected to the spool 18_a
In the position shown in the figure, connect the circuit 23 to the D range pressure circuit 19,
Le 18 _aCircuit 23 is switched to 2-range pressure circuit 20 at the lower position in the figure.
The connection shall be switched. And the valve 18 is the spool 18_a
Pilot pressure P of circuit 17 at the upper end of_PIs always acting and the reverse
Orientation spring 18_bAnd the circuit from the circuit 24
Spool 18 depending on the presence or absence of pressure from 24_aThe position shown
It is assumed that the stroke is controlled between the lower position and the lower position.

On the other hand, the D-range pressure circuit 19 is connected to the switching valve 16 and the overrun clutch control valve 25, and is connected to a D-range shift control oil passage not shown in FIG. 3 (a) of the shift solenoids A and B. 1) achieves the hydraulic supply logic indicated by a circle in the table of FIG. 1 and automatically selects the first to fourth speeds. However, the shift solenoids A and B are the pilot pressures P _{P of the} circuit 17 when they are ON.
Is output to the circuits 26 and 27 as the shift signal pressure,
Drain 26, 27.

The changeover valve 16 is acting four-speed selection pressure P ₄ of the circuit 28 to the upper end of the spool 16 _a, the spring 16 _b and a circuit in the opposite direction
It is act 2 range pressure P ₂ from 20, the control valve control circuit 29 from overrunning clutch control valve 25 is communicated to the circuit 24 from the forward clutch control valve 18 to the line pressure circuit 13 in the illustrated position of the spool 16 _a through the circuit 30 from the solenoid C, and the circuit 30 the circuits 24 in the lowered position of the spool 16 _a, also the circuit 29 D-range pressure circuit
The connection shall be switched to 19.

The fourth speed selection pressure P ₄ in the circuit 28 is a pressure generated when the fourth speed is to be selected in the above-mentioned automatic shifting, and this pressure is applied when the overrun clutch control valve 25 passes the circuit 31 through the circuit 28. The fourth speed can be selected by being supplied to the fourth speed servo apply chamber 4A of the brake B / B. The control valve control solenoid C is the same as the shift solenoids A and B, and outputs the pilot pressure of the ON-time circuit 17 to the circuit 30 and drains the circuit 30 when OFF.

The overrun clutch control valve 25 has _a spring 24a at the upper end of the spool and one range pressure P _{1 of the} circuit 21.
Is act, is acted the pressure of the circuit 29 in the opposite direction, through the circuit 28 in the lowered position shown in drain port 25 _c, also the circuit 32 from overrunning clutch OR / C to the D range pressure circuit 19, increases circuit 28, 32 is assumed to be connected is switched to the respective circuits 31 and drain port 25 _c in position.

The operation of the above embodiment will now be described. The solenoids A, B, and C are controlled by the controller 41 as described below, and execute predetermined gear shifting and engine brake control. During the automatic shifting operation with the manual valve 14 in the D range, the controller 41 determines a suitable gear position according to the traveling state from input information, and turns on the shift solenoids A and B shown in FIG. , OFF, the first to fourth speeds are selected by the logic shown in the table of FIG.
In the first speed to third speed without the occurrence of 4-speed selection pressure P _4, the switching valve 16 is in the raised position illustrated spool 16 _a, circuit 24, 29
Are connected to the circuits 13 and 30. Thus, the supply line pressure in the circuit 24, the forward clutch control valve 18 is in the raised position illustrated spool 18 _a. As a result, the D range pressure output to the circuit 19 in the D range is applied to the valve 18 and the circuit
Through 23, a forward clutch F / C is reached, which is maintained in an engaged state, and the first to third speeds can be selected.

When a running condition requiring an engine brake at the first to third speeds is reached, the controller 41 determines this and turns off the solenoid C to drain the circuit 30. Therefore, the circuit 29 connected to the circuit 30 is also drained, and the overrun clutch control valve 25 connects the circuit 32 to the D range pressure circuit 19 to engage the overrun clutch OR / C, thereby realizing automatic engine braking. . Thus, when the engine brake is not required, the pilot pressure is supplied to the circuit 30 by turning on the solenoid C,
This is supplied to the valve 25 via the circuit 29.
Together with release through the overrunning clutch OR / C to the drain port 25 _c, and through the circuit 28 to the circuit 31.

[0030] Therefore, when the circuit 31 is 4-speed selection pressure P ₄ generated from this circuit 28, the band brake B / B chamber 4
As a result, the fourth speed can be selected by engaging the band brake.

By the way, in the fourth speed selection state acts on the upper end of the 4-speed selection pressure P ₄ switching valve 16, also a possible 2-range pressure P ₂ acting on the lower end does not exist in the D-range, The switching valve 16 is in the lowered position and switches and connects the circuits 24, 29 to the circuits 30, 19, respectively. Forward clutch control valve by solenoid C through communication of circuits 24 and 30
18 can be controlled, and the overrun clutch control valve 25 is
To allow fastening holding (fourth gear selection holding) and a lowered position holding the switching valve 16 of the band brake B / B by speed pressure P _4.

Here, in the fourth speed selection state, the controller 41 turns off the solenoid C. This causes the forward clutch control valve 18 to be in the lowered position by the drain of the circuit 30, and thus the drain of the circuit 24, and the circuit 23 is switched to the two-range pressure circuit 20. By the way, in the D range, since the two-range pressure circuit 20 is drained, the operating pressure of the forward clutch F / C is drained via this and can be released. From the above,
Forward clutch F that does not contribute to power transmission in fourth speed
/ C is deactivated, so that the friction of the forward one-way clutch FO / C described above with reference to FIG. 1 can be prevented to improve fuel efficiency.

Next, a description will be given of a 4 → 3 downshift according to the present invention. In this shift, the controller
41 executes the control program shown in FIG.
The shift is performed as shown in FIG.

That is, in the operation state in which the third speed is to be selected in the fourth speed selection state, the controller 41 starts the operation shown in FIG.
In the instant t ₁ 4 → 3 issues a shift command. At this time, the controller 41 first resets a timer T for measuring an elapsed time from the shift command in step 51 of FIG. In the next step 52, the shift solenoid A is switched from ON to OFF as is clear from the logic table of FIG. At the same time, in step 53, the overrun clutch solenoid C is turned off.

The OFF state of the shift solenoid A is determined by the circuit 31-4.
By the speed pressure P ₄ is reduced to as in FIG. 5, which switched to the position in FIG. 2 by the switching valve 16 spring 16 instantaneously t ₂ became set pressure _b circuit 13, 24 and between 29, 30 Pass through. When the circuits 13 and 24 are opened, the forward clutch control valve 18 is also switched to the position shown in FIG.
The clutch pressure is increased by increasing the engagement pressure P _{F / C} of FIG. 5 as shown in FIG. 5, but this increase in pressure is due to the fact that the cylinder capacity of the forward clutch F / C itself is large and the forward clutch pressure circuit 23 The main reason that an accumulator for preventing a shift shock (not shown) is connected is a delay.

At the same time, the turning off of the overrun clutch solenoid C performed in step 53 causes the signal pressure from the solenoid C reaching the overrun clutch control valve 25 via the switching valve 16 switched as described above to disappear. With the control valve 25 in the state of FIG. 2, the engagement pressure P _{OR / C} of the overrun clutch OR / C is increased as shown in FIG. 5, and this clutch is forcibly engaged regardless of the engine brake control. This pressure rise is rapid because the cylinder capacity of the overrun clutch OR / C is small and the overrun clutch OR / C is not connected to the accumulator.

On the other hand, the overrun clutch OR / C is arranged in parallel with the forward clutch F / C and the forward one-way clutch FO / C as is apparent from FIG. The start of engagement can compensate for the above-described engagement delay of the forward clutch F / C, and the automatic transmission does not enter the neutral state even by this engagement delay.
As can be seen from the change in the engine speed, it is possible to avoid a delay in shifting and an engine blow.

The engagement of the overrun clutch OR / C causes the automatic transmission to be in an engine brake enabled state.
Since the downshift is normally performed during power-on traveling with the accelerator pedal depressed, there is no problem such as causing a shock.

In steps 54 and 55 of FIG. 4, the timer T is incremented so that the 4 → 3 downshift gearshift command instant t _{1 is} reached.
The elapsed time from the start of the shift is measured, and this reaches a set time T _S (for example, 0.7 seconds) corresponding to the time required for the shift.
Of advanced control instant t ₄ in step 56, and ends the control to open the overrun clutch OR / C by ON overrun clutch solenoid C.

In the above-described example, the control of the overrun clutch according to the present invention is ended by setting the lapse of the set time T _S from the shift command to the end of the shift. Needless to say, it is more accurate to monitor and determine the engine speed.

[0041]

Thus, the transmission control apparatus according to the present invention is described in claim 1.
As described above, a low speed stage (third in the illustrated example) that transmits power via a one-way clutch (a forward one-way clutch FO / C in the illustrated example) by engaging a certain friction element (forward clutch F / C in the illustrated example). In the (speed) selected state, it is possible to obtain the engine brake at the low speed stage by engaging the friction element for engine brake (the overrun clutch OR / C in the illustrated example) arranged in parallel with the certain friction element and the one-way clutch. Also, when another friction element (band brake B / B in the illustrated example) is engaged in the low-speed gear selection state, the shift to the high-speed gear (fourth gear in the illustrated example) is performed by overrun of the one-way clutch. The friction of the one-way clutch can be prevented by releasing the engagement of the certain friction element in the high speed stage selected state. In automatic transmission in the manner that, downshift detecting means for detecting during the shift to the low speed stage from said high-speed stage and (controller 41 in the illustrated example),
A shift delay compensating means (an overrun clutch solenoid C in the illustrated example) is provided for engaging the engine braking friction element during the shift detection and compensating for the engagement delay of the certain friction element. Even if the engagement of a certain friction element tends to be delayed during the shift from the high gear to the low gear, this can be compensated by the engagement of the friction element for engine braking, so that the automatic transmission operates during the gear shift. It is possible to avoid such an inconvenience that the engine is temporarily in a neutral state and the engine is idling, or a large shift shock is caused by the idling.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a power transmission train of an automatic transmission to which a shift control device of the present invention is applied, together with a fastening logic table of various friction elements.

FIG. 2 is a circuit diagram showing only a shift control hydraulic circuit of the transmission train according to the present invention.

FIG. 3 is a logical table showing a relationship between ON / OFF of a shift solenoid and a selected shift speed in the shift control hydraulic circuit.

FIG. 4 is a 4 → 3 downshift shift control program executed by the controller in the example.

FIG. 5 is an operation time chart of the automatic transmission based on the shift control.

FIG. 6 is a shift operation time chart in a conventional automatic transmission.

[Explanation of symbols]

Reference Signs List 1 torque converter 2 input shaft 3 output shaft 4 first planetary gear set 5 second planetary gear set F / C forward clutch (certain friction element) B / B band brake (other friction element) FO / C forward one-way clutch ( One-way clutch) H / C High clutch OR / C Overrun clutch (friction element for engine brake) R / C Reverse clutch LR / B Low reverse brake A Shift solenoid B Shift solenoid C Control valve control solenoid (Shift delay compensation means) 11 Regulator valve 12 Oil pump 14 Manual valve 15 Pilot valve 16 Switching valve 18 Forward clutch control valve 25 Overrun clutch control valve 41 Controller (downshift change detection means)

Claims (1)

(57) [Claims] In a selected state of a low speed stage in which power is transmitted via a one-way clutch by engagement of a certain friction element, the engagement of an engine brake friction element arranged in parallel with the certain friction element and the one-way clutch is performed. It is possible to obtain an engine brake at a low speed stage, and when engaging another friction element in the low speed stage selection state,
A shift to a high speed stage can be performed by overrun of the one-way clutch. In this automatic transmission, the friction of the one-way clutch is prevented by releasing engagement of the certain friction element in the high speed stage selection state. Downshift transmission detecting means for detecting during a shift from the high speed stage to the low speed stage; and a shift delay for engaging the engine brake friction element during the shift detection to compensate for the engagement delay of the certain friction element. A shift control device for an automatic transmission, comprising a compensation means.