JP2867827B2 - 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 the high gear (fourth gear), the stroke of the valve for performing this release is controlled. The signal pressure is always set to 0 while the high-speed stage is selected, and it is necessary to continue draining the base pressure of this signal pressure during the high-speed stage selection. Due to the fact that the engine speed is low when the high-speed stage is selected, this drain tightens the working fluid balance environment of the pump driven by the engine, especially during low vehicle speeds, and locks the torque converter, which further reduces the engine speed. The upper limit vehicle speed must be set higher. Therefore, the lock-up region is narrowed, and the lock-up period for directly connecting the input / output elements of the torque converter is shortened.
A large fuel efficiency improvement effect due to the lockup of the torque converter cannot be expected.

According to the present invention, the effect of improving the fuel efficiency by lock-up of the torque converter is more than the effect of improving the fuel efficiency obtained by releasing the engagement of the certain friction element during the selection of the high-speed gear and preventing the friction of the one-way clutch. Based on the fact that it is larger, the control to open the friction element for selecting the low-speed gear is prohibited during low-vehicle speeds where the working fluid balance environment of the pump is severe as described above, even when the high-speed gear is selected. It is an object of the present invention to eliminate the need to set the upper region lower limit vehicle speed higher, thereby solving the above-described problem.

[0009]

SUMMARY OF THE INVENTION To this end, a transmission control apparatus according to the present invention is provided in which a certain friction element and a one-way clutch are selected in a low speed stage in which power is transmitted via a one-way clutch by engagement of a certain friction element. By engaging the friction element for engine brake arranged in parallel with the clutch, it is possible to obtain the engine brake at the low speed stage, and when the other friction element is engaged in the low speed stage selection state, the over-speed of the one-way clutch can be obtained. A shift to a high speed stage can be performed by a run, and vehicle speed is detected in an automatic transmission in which friction of the one-way clutch is prevented by releasing engagement of the certain friction element in the high speed stage selection state. Vehicle speed detecting means; low vehicle speed detecting means for detecting that the vehicle speed detected by the means is lower than a set vehicle speed; Among fast it is provided with a friction element release inhibiting means for inhibiting the release of the certain friction element in the high-speed stage selection state.

[0010]

The automatic transmission is in a low speed stage selection state in which power is transmitted via a one-way clutch when a certain friction element is engaged, 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 gear position, the automatic transmission is shifted to the high gear by the overrun of the one-way clutch. Then, by disengaging the certain friction element in the high-speed gear selection state, it is possible to prevent unnecessary one-way clutch friction from occurring at the gear, and to improve fuel efficiency.

When the low vehicle speed detecting means detects that the vehicle speed detected by the vehicle speed detecting means is lower than the set vehicle speed, the friction element release prohibiting means prohibits the release of the certain friction element. Accordingly, the fuel efficiency improvement effect obtained by preventing the friction of the one-way clutch by releasing the engagement of the certain friction element cannot be obtained. However, the signal pressure of the valve that controls this control is reduced to 0 (the base pressure is reduced). (Draining) is no longer necessary, and even if the engine speed is low due to the high speed stage, the working fluid balance environment of the pump driven by the engine is improved, and the lower limit of the lock-up area of the torque converter causing the engine speed to decrease. There is no need to set a higher vehicle speed, thereby improving fuel efficiency. And since the fuel efficiency improvement effect by the lock-up is superior to the fuel efficiency improvement effect by the friction prevention of the one-way clutch, even if the latter fuel efficiency improvement effect is sacrificed, the fuel efficiency can be improved overall.

[0013]

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 torque converter 1 includes a pump impeller (input element) 1a driven by an engine, a turbine runner (output element) 1b, and a lock-up clutch 1c. Usually, the output element 1b is driven by the input element 1a via an internal working fluid. When the input / output elements 1a and 1b are directly connected by engagement of the lock-up clutch 1c (at the time of lock-up), the engine power is mechanically transmitted. It shall be transmitted directly to the input shaft 2.

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.

Reference numeral 11 denotes a regulator valve which regulates hydraulic oil from an oil pump 12 driven by an engine to a predetermined line pressure P _L by a well-known operation, and uses the regulated line pressure P _L as all base pressures of the automatic transmission. Output to the circuit 13. The line pressure is the manual valve 14, the pilot valve 15, is supplied to the switching valve 16, the pilot valve 15 is constant pilot pressure P _P ungated and reduces the line pressure P _L, which forward clutch control valve by the circuit 17 18 , Shift solenoids A and B and overrun 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 respectively controlled by the controller 41 as described below, and execute predetermined shift and engine brake control. For this reason, various input information including the vehicle speed V detected by the vehicle speed sensor 42 is supplied to the controller 41. 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 places the spool 16a in the raised position shown, and connects circuits 24, 29 to circuits 13, 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
The D range pressure output to the circuit 19 in the range
To the forward clutch F / C, which is maintained in the 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.
Releases the overrun clutch OR / C through the drain port 25c and connects 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, the engagement and disengagement control of the forward clutch F / C in the fourth speed selection state according to the present invention will be described. In this control, the controller 41 executes the control program shown in FIG. 4 to execute the control.

That is, FIG. 4 is repeatedly executed during the selection of the fourth speed. First, at step 51, the vehicle speed V is read, and at step 52, which corresponds to low vehicle speed detecting means, this vehicle speed V is equal to or higher than the set vehicle speed Vs. It is checked whether the vehicle speed is high or low vehicle speed less than Vs. Here, the set vehicle speed Vs is such that when the solenoid C is turned off in order to deactivate the forward clutch F / C that does not contribute to power transmission as described above in the fourth speed selection state, the amount of oil drained from the solenoid C is: The upper limit of the vehicle speed range is set to make the oil amount balance environment of the pump 12 driven by the engine severe. Accordingly, in a high vehicle speed region where the vehicle speed V is equal to or higher than the set vehicle speed Vs, the rotation of the pump 12 is sufficient, and the oil amount balance environment is good, and even if the engine speed decreases due to the lock-up of the torque converter 1, the oil amount balance environment remains unchanged. At a low vehicle speed lower than the set vehicle speed Vs while maintaining a good state, when the engine speed is reduced due to lock-up of the torque converter 1, the amount of drain oil from the solenoid C makes the oil amount balance environment severe.

From the above, at the high vehicle speed described above, in step 53, the forward clutch F / C is disengaged by turning off (drain) the control valve control solenoid C as described above, and the forward one-way clutch FO is executed. Eliminate friction of / C and improve fuel efficiency.

At the low vehicle speed, the control valve control solenoid C is turned on at step 54 corresponding to the frictional element release prohibiting means, and the drainage thereof is prohibited (the release of the forward clutch F / C is prohibited). In addition, the environment of the oil balance of the pump 12 due to the amount of drain oil from the solenoid C is prevented from becoming severe. Therefore, in determining the lock-up region of the torque converter 1 that causes a decrease in the engine rotation (a decrease in the pump oil amount), it is not necessary to set the lower limit of the vehicle speed higher, and the lock-up period can be maintained longer. Thus, fuel efficiency can be improved.

According to this control, since the release of the forward clutch F / C is prohibited, the effect of improving fuel economy (by preventing the friction of the forward one-way clutch FO / C) cannot be obtained. Since the effect of improving the fuel economy by extending the lock-up period is greater, the fuel economy can be improved overall by the difference between the two.

[0038]

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) in which power is transmitted through a one-way clutch (a forward one-way clutch FO / C in the illustrated example) by engagement of a certain friction element (a 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 the automatic transmission which is adapted to, when (in the illustrated example the controller 41) low vehicle speed detecting means that the vehicle speed V detected is lower than the set vehicle speed Vs by the vehicle speed detecting means (vehicle speed sensor 42 in the illustrated example) is detected,
Friction element release inhibiting means (controller 41 in the illustrated example)
Has been configured to prohibit the release of the certain friction element,
Although the effect of improving fuel economy obtained by preventing the friction of the one-way clutch by releasing the engagement of the certain friction element cannot be obtained, the signal pressure of the forward clutch control valve 18 which controls this control is set to 0 (the base pressure). (Draining of the pressure) is eliminated, so that even if the engine speed is low due to the high speed stage, the working fluid balance environment of the pump 12 driven by the engine is improved, and the torque converter 1 which reduces the engine speed is reduced. It is no longer necessary to set the lockup region lower limit vehicle speed higher, and fuel efficiency can be improved by extending the lockup period.

Since the effect of improving the fuel efficiency by extending the lock-up period is superior to the effect of improving the fuel efficiency by preventing friction of the one-way clutch, even if the latter effect is sacrificed, the difference between the two is generally reduced. Fuel efficiency can be improved.

[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 flowchart showing a forward clutch engagement control program in a fourth speed selection state executed by a controller in the example.

[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 41 Controller (low vehicle speed detection means, friction element release prohibition means) 42 Vehicle speed sensor (vehicle speed detection means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

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, an engine brake friction element arranged in parallel to the certain friction element and the one-way clutch is engaged to apply the power. 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. A vehicle speed detecting means for detecting a vehicle speed; a low vehicle speed detecting means for detecting that the vehicle speed detected by the means is lower than a set vehicle speed; A shift control device for an automatic transmission, comprising: a friction element release prohibiting unit that prohibits release of a friction element.