JP2861704B2 - 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, so that the friction of the one-way clutch due to the relative rotation between the inner and outer races cannot be avoided. 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 the 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.

Namely, the detail per the automatic transmission in the prior invention, the instantaneous t ₁ from 4 speed pressure P ₄ downshift command to the fourth speed to the third speed is issued as shown in FIG. 4 Then, the forward clutch pressure P _{F / C} increases at the instant t _2. However, the forward clutch is inevitably subjected to the engagement delay due to the above-mentioned reason, and temporarily sets the automatic transmission to the neutral state during the shift. By the way, since the downshift usually occurs during the power-on running with the engine accelerator pedal depressed, the engine is turned off at this time.
Racing and immediately before the forward clutch engagement start instant t ₃ as shown in, not only the transmission delay, generates a large shift shock due to racing.

The present invention is based on the viewpoint that the engagement delay of the friction element (forward clutch) for selecting the low-speed gear is mainly based on the stroke of the accumulator.
An object of the present invention is to solve the above-mentioned problem by preventing the stroke of the accumulator from occurring during the downshift to the lower gear.

[0010]

SUMMARY OF THE INVENTION To this end, the present invention is directed to a friction element, which is fastened by an accumulator at a hydraulic pressure whose pressure rise rate is moderated, through the friction element and the one-way clutch. A low speed stage for performing power transmission is selected, and in the low speed stage selection state, an engine brake at the low speed stage can be obtained by fastening an engine brake friction element arranged in parallel with the one-way clutch. When another friction element is engaged in the low speed stage selection state, a shift to a high speed stage can be performed by the overrun of the one-way clutch, and the engagement of the certain friction element is released in the high speed stage selection state. In an automatic transmission configured to prevent friction of a one-way clutch, the pressure existing during a shift from the high speed stage to the low speed stage is reduced by the acceleration. It led to Suit of Lights, in which the accumulator is provided an accumulator stroke prohibition circuit for stroke disabled.

[0011]

In the automatic transmission, a certain friction element is fastened by hydraulic pressure controlled to rise by an accumulator.
Although a low gear stage is selected in which power transmission is performed via the one-way clutch, the engine brake does not work in the low gear stage because the power is transmitted through the one-way clutch. In a running state in which engine braking is required, overrunning of the one-way clutch is disabled by engaging an engine braking friction element provided in parallel with the one-way clutch, thereby enabling engine braking at the low speed stage.

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.

When the certain frictional element is re-engaged in the downshift from the high speed stage to the low speed stage, an accumulator stroke prohibition circuit supplies the accumulator with the pressure existing at the time of the speed change. Make stroke impossible. For this reason, the accumulator does not cause a delay in fastening the certain friction element, and the fastening can be completed quickly.
Therefore, at the time of the downshift, the above-mentioned shift delay and engine idling due to the engagement delay of a certain friction element,
In addition, a shift shock does not occur, and the commercial value of the automatic transmission can be increased.

[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.

The D-range pressure circuit 19 is connected on the one hand to a forward clutch control valve 18, which is connected to a spool 18a.
The circuit 23 is connected to the D-range pressure circuit 19 at the illustrated position, and the circuit 23 is switched and connected to the two-range pressure circuit 20 at the lowered position of the spool 18a in the drawing. And the valve 18 is a spool 18a
The upper end is always applied to the pilot pressure P _P of the circuit 17, the is operatively pressure from the spring 18b and the circuit 24 in the opposite direction, the circuit
The spool 18a is moved to the position shown in FIG.
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 16a, a spring 16b and the circuit in the opposite direction
Is act 2 range pressure P ₂ from 20, the control valve control solenoid circuit 29 from overrunning clutch control valve 25 with the circuit 24 from the forward clutch control valve 18 in the illustrated position of the spool 16a leading to the line pressure circuit 13 C to the circuit 30. At the lower position of the spool 16a, the circuit 24 is connected to the circuit 30 and the circuit 29 is connected to the 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.
The pressure in the circuit 29 is applied in the reverse direction, and the circuit 28 is connected to the drain port 25c at the lowered position shown in the drawing, and the circuit 32 from the overrun clutch OR / C is connected to the D range pressure circuit 19, and the ascending position is set. The circuits 28 and 32 are switched and connected to the circuit 31 and the drain port 25c, respectively.

The operation of the above embodiment will now be described. The solenoids A, B, and C are controlled by the controller 41 as follows, and execute predetermined shift 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 16a, the circuit 24, 29
Are connected to the circuits 13 and 30. Thus, line pressure is supplied to the circuit 24, and the forward clutch control valve 18 moves the spool 18a to the illustrated raised position. 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.

Incidentally, a one-way orifice 33 and an accumulator 34 are sequentially inserted into the circuit 23, whereby the operating oil pressure of the forward clutch F / C gradually increases. Therefore, the forward clutch F / C
Does not become steep, and when the fastening shock, that is, when the manual valve 14 is started, is shifted from the P (N) range to D
By switching to the range, the forward clutch F /
The so-called N → D select shock when C is engaged from the released state can be reduced.

In the present embodiment, the pressure existing in the accumulator 34 at the time of shifting from the fourth speed to the third speed, that is, as the pressure existing in the third speed and the fourth speed, for example, as is clear from the table of FIG. An accumulator stroke prohibition circuit 35 for guiding the operating pressure of the high clutch H / C is provided, so that the accumulator for the third speed and the fourth speed, and therefore when shifting from the fourth speed to the third speed, is used for the purpose to be described later. 34 is held in a state where the stroke is impossible.

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.
Releases the overrun clutch OR / C through the drain port 25c and connects the circuit 28 to the circuit 31.

[0032] 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
Reference numeral 41 switches the shift solenoid A from ON to OFF as is clear from the logic table of FIG. OFF of the shift solenoids A reduces the 4 speed pressure P ₄ of the circuit 31, which is switched to the position in FIG. 2 by the switching valve 16 spring 16b instantly became set pressure determined by the set load of the spring 16 _b, It passes between circuits 13 and 24 and between 29 and 30. When the circuits 13 and 24 are opened, the forward clutch control valve 18 is also switched to the position shown in FIG. 2 and the engagement pressure P of the forward clutch F / C is increased.
_{Raise F / C} and engage this clutch.

Incidentally, the forward clutch F /
Since the accumulator 34 is held at the position shown in FIG. 2 by the operating pressure of the high clutch H / C at the time of the shift and the stroke is not possible, the increase of the engagement pressure P _{F / C} of _C is selected from N → D. Accumulator 34 for shock prevention
Progresses promptly due to the presence of Therefore, the instantaneous neutral state of the automatic transmission due to the delay of the engagement of the forward clutch F / C described with reference to FIG. 4 can be avoided.
Accordingly, it is possible to prevent a shift delay, engine idling, and a large shift shock accompanying the shift.

[0037]

Thus, the transmission control apparatus according to the present invention is described in claim 1.
As described in the above, when a certain friction element (forward clutch F / C in the illustrated example) is engaged with a hydraulic pressure whose pressure increasing speed is moderated by the accumulator 34, the friction element and the one-way clutch (in the illustrated example) are engaged. A low-speed stage (third speed in the illustrated example) for transmitting power via the forward one-way clutch FO / C is selected. In this low-speed stage selection state, an engine brake friction element (parallel to the one-way clutch) is arranged. In the illustrated example, the engine brake at the lower gear can be obtained by engaging the overrun clutch OR / C, and other friction elements (band brakes B / B in the illustrated example) are engaged in the low gear selected state. In this case, the shift to a high gear (fourth gear in the illustrated example) can be performed by the overrun of the one-way clutch. In the automatic transmission in which the friction of the one-way clutch is prevented by releasing the engagement of the certain friction element, the pressure existing at the time of shifting from the high speed stage to the low speed stage (in the illustrated example, the high clutch H / C Operating pressure) to the accumulator 34,
Since the circuit 35 for disabling the accumulator is provided, the operating pressure of the certain friction element to be fastened from the released state during the shift from the high speed stage to the low speed stage can be quickly increased also by the presence of the accumulator 34. Therefore, it is possible to avoid the above-described delay in fastening of a certain friction element. Therefore, it is possible to prevent the engine from running idle and the shift from being delayed due to the engagement delay, and to prevent a large shift shock due to these.

[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 logic chart 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 shift operation time chart of 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 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 33 One-way orifice 34 Accumulator 35 Accumulator stroke prohibition circuit 41 Controller

Continuation of the front page (56) References JP-A-5-209676 (JP, A) JP-A-6-109128 (JP, A) JP-A-6-109133 (JP, A) JP-A-2-225871 (JP) , A) JP-A-2-296072 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 59/00-61 / 12,61 / 16-61/2 4,63 / 40-63/48

Claims (1)

(57) [Claims] When a certain friction element is fastened by a hydraulic pressure whose pressure rising speed is moderated by an accumulator, a low speed stage for transmitting power via the friction element and a one-way clutch is selected, and the low speed stage is selected. In the gear selection state, the engine brake in the low gear can be obtained by engaging the engine brake friction element arranged in parallel with the one-way clutch, and other friction elements are engaged in the low gear selection state. Time,
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. A shift control device for an automatic transmission, comprising: an accumulator stroke prohibition circuit that guides pressure existing at the time of shifting from the high speed stage to the low speed stage to the accumulator and disables the accumulator.