JP2001041317A - Control method for vehicular automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a control method for a vehicular automatic transmission capable of reducing a shock of re-engagement at the time of exacting excessive play elimination for starting re-engagement when a friction engaging element changes its state like as engage to release to engage. SOLUTION: When a friction engaging element attaining a specified shift stage changes its state like as engage to release to engage (S1), high hydraulic pressure is supplied to the friction engaging element for exacting excessive play elimination at the time of starting re-engagement (S2). As keeping time Tn of a releasing state is shortened, excessive play elimination time Tc or excessive play elimination pressure Pc is set to be small (S4, S6). Therefore, a shock at re-engaging can be reduced while resolving delays in engaging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for an automatic transmission for a vehicle, and more particularly to a control for reducing the frictional engagement element.

[0002]

2. Description of the Related Art Conventionally, a plurality of friction engagement elements are provided, and a hydraulic pressure is supplied to these friction engagement elements to selectively engage the friction engagement elements to achieve a plurality of shift speeds. Automatic transmissions are known. The friction engagement element has a piston that receives the control oil pressure to fasten the clutch plate and a return spring that returns and urges the piston. However, even when the control oil pressure is supplied to the piston, the engagement starts immediately. It does not mean. That is, an invalid stroke occurs until the piston moves against the return spring under the oil pressure and comes into contact with the clutch plate, which causes a delay in engagement. In order to eliminate such an engagement delay, in a conventional automatic transmission, a high oil pressure (for example, a line pressure) is temporarily applied at the start of engagement of a friction engagement element to eliminate an invalid stroke in a short time. It is widely practiced to backlash.

[0003] For example, Japanese Patent Application Laid-Open No. 8-254262 discloses that when shifting from N to D, the time required for shifting to be started after the end of backlash is longer than the upper limit value, the backlash time is increased. There is disclosed a system in which learning control is performed so as to reduce the backlash time when the time required until the shift is started after the backlash is completed is shorter than the lower limit value.

[0004]

However, D → N
When the frictional engagement element is continuously changed from engagement to release to engagement as in → D or R → N → R, the re-engagement may be delayed depending on the length of the release time. A large engagement shock may occur.

FIG. 9 shows the current supplied to the solenoid valve for controlling hydraulic pressure to the friction engagement element, the supply hydraulic pressure of the friction engagement element, when the shift lever is switched from N → R → N → R.
6 shows changes with time of the output torque of the friction engagement element. In addition,
Here, the output oil pressure is ON when the current is OFF as a solenoid valve
A normally open valve was used. In FIG. 9, t _{1 to} t _{2 are the} clearance time, t _{2 to} t ₃ are the transient control time, t _{3 to} t ₄ are the fastening time, t _{4 to} t ₅ are the holding time of the N range, and t _{5 to} t _{5.
6 is a} loosening time, and t _{6 to} t ₇ are transient control times.

As shown in FIG. 9, when the holding time t _{4 to} t ₅ of the N range is short, the next backlash starts in the presence of the residual pressure Pr, so that the friction engagement element is There is a problem that the engagement is sudden and the shock S occurs. This problem tends to occur particularly at low temperatures. A similar phenomenon may occur during traveling. In other words, when the vehicle is traveling in the D range, when the gear position fluctuates up and down with an accelerator operation, a certain frictional engagement element may repeat engagement to disengagement to engagement. Even in such a case, backlash is performed at the time of re-engagement, but if the release time is short, a shift shock due to residual pressure may occur at the time of re-engagement.

Therefore, an object of the present invention is to provide a shock at the time of re-engagement when the frictional engagement element changes state from engagement to disengagement to engagement at the start of re-engagement. An object of the present invention is to provide a control method of an automatic transmission for a vehicle, which can be reduced.

[0008]

The above object is achieved by the present invention. That is, the invention according to claim 1 has a plurality of friction engagement elements, and selectively supplies the friction engagement elements by supplying hydraulic pressure to the friction engagement elements, thereby achieving a plurality of shift speeds. In the automatic transmission for a vehicle, when the frictional engagement element that achieves the predetermined gear position changes state from engagement to disengagement to engagement, the frictional engagement element A method for controlling an automatic transmission for a vehicle, characterized in that a high hydraulic pressure is supplied and the amount of backlash is set smaller as the holding time of the released state becomes shorter.

According to a second aspect of the present invention, a plurality of friction engagement elements are provided, and the friction engagement elements are selectively engaged by supplying a hydraulic pressure to these friction engagement elements, so that a plurality of gear shifts are provided. In the automatic transmission for a vehicle that achieves the gear, when the frictional engagement element that achieves the predetermined gear changes state from engagement to release to engagement, the release state holding time is When the set time is exceeded, high pressure is supplied to the friction engagement element at the start of re-engagement, and backlash is performed.
A method for controlling an automatic transmission for a vehicle, characterized in that when the holding time of the released state is shorter than a set time, the rattling is prohibited.

When the state of the frictional engagement element changes from engagement to release to engagement, if the release state is maintained for a long time, the residual pressure is completely eliminated. When the stuffing is started, the frictional engagement elements do not suddenly engage, so that a shock can be avoided. On the other hand, if the holding time of the released state is short, the residual pressure is not completely eliminated until the re-engagement starts, and a shock occurs. Therefore, in the first aspect, the shock at the time of re-engagement is avoided by reducing the amount of backlash. As a concrete method of reducing the amount of backlash, a method of shortening the backpacking time as the holding time in the released state becomes shorter, and a method of lowering the backpacking oil pressure as the holding time of the released state becomes shorter. There is. Either way,
By reducing the amount of backlash as the holding time of the released state becomes shorter, it is possible to achieve both the elimination of the engagement delay and the reduction of the shock at the time of re-engagement.

Further, in the case of claim 2, when the holding time of the released state is shorter than the set time, the rattling itself is prohibited. In this case, as in the method of the first aspect, there is an advantage that both the elimination of the delay in engagement and the reduction of the shock at the time of re-engagement can be achieved, and the control is simplified.

According to a third aspect of the present invention, only when the oil temperature of the automatic transmission is lower than the set temperature, the amount of stuffing is set smaller as the holding time of the released state becomes shorter, or the holding time of the released state is set at the set time. Prohibits stuffing at shorter times. That is, play control is performed in consideration of not only the release time but also the condition of the oil temperature. That is, AT
When the F oil temperature is low, the viscosity of the oil increases, and the fall of the oil pressure becomes slow. Therefore, the relationship between the holding time (disengagement time) and the engagement shock also differs at high temperatures. Therefore, only when the oil temperature is lower than the set temperature, as in the present invention, as the holding time of the released state becomes shorter, the amount of backpack is set smaller,
Alternatively, when the holding time of the release state is shorter than the set time, rattling is prohibited, and when the oil temperature is higher than the set temperature, the normal padding control is performed. Thereby, the re-engagement shock at the time of low temperature can be reduced.

According to the control method of the present invention, in addition to a shock (called a garage shock) when the shift lever is switched to the drive range (D or R) across the N range,
It can also be used to avoid shifting shocks that occur during running.

[0014]

FIG. 1 shows a vehicle system equipped with an automatic transmission for a vehicle according to the present invention. The output of the engine 1 is transmitted to a transmission mechanism 4 via a torque converter 3 of the automatic transmission 2, and the transmission mechanism 4 is connected to wheels (not shown) via an output shaft 5. The automatic transmission 2 includes an oil pump 6 driven by the engine 1 via a torque converter 3, and a discharge pressure of the oil pump 6 is sent to a hydraulic control device 7. The hydraulic control device 7 includes first to fourth solenoid valves 21 to 24, and these solenoid valves 21 to 24 are provided.
By controlling the controller 24 with the controller 20, the hydraulic pressures of the various frictional engagement elements incorporated in the transmission mechanism 4 are controlled in accordance with various signals corresponding to the traveling state. Here, signals such as the shift position, engine speed, vehicle speed, throttle opening, and ATF oil temperature are input to the controller 20, but other signals (turbine speed in place of engine speed) are input. You may.

FIG. 2 shows an example of the transmission mechanism 4. The transmission mechanism 4 includes an input shaft 10 to which engine power is transmitted via a torque converter 3, three clutches C1 to C3 and two brakes B1 and B2, which are frictional engagement elements, a one-way clutch F, a Ravigneaux type planet. A gear mechanism 11, a differential device 14, and the like are provided.

The forward sun gear 1 of the planetary gear mechanism 11
1a and the input shaft 10 are connected via a C1 clutch, and the rear sun gear 11b and the input shaft 10 are connected via a C2 clutch. The carrier 11c is connected to the center shaft 15, and the center shaft 15 is C3
It is connected to the input shaft 10 via a clutch. Also,
The carrier 11c is connected to the transmission case 16 via a B2 brake and a one-way clutch F that allows only the forward rotation (engine rotation direction) of the carrier 11c. The carrier 11c supports two types of pinion gears 11d and 11e, and the forward sun gear 11a meshes with a long pinion 11d having a long shaft length, and the rear sun gear 11b
Is engaged with the long pinion 11d via the short pinion 11e having a short shaft length. Long pinion 11d
The ring gear 11f that meshes with only the output gear 12 is connected to the output gear 12. The output gear 12 is connected to a differential 14 via an intermediate shaft 13.

The transmission mechanism 4 includes clutches C1, C2, C
3. By operating the brakes B1 and B2 and the one-way clutch F, four forward speeds and one reverse speed are realized as shown in FIG. In FIG. 3, ● indicates the operating state of the hydraulic pressure. The B2 brake is engaged at the time of retreat and at the first speed of the L range. FIG. 3 also shows the operating states of the first to fourth solenoid valves 21 to 24. ○ is the energized state,
× indicates a non-energized state, and Δ indicates a temporary energized state. In addition,
This operation table shows an operation in a steady state.

The first solenoid valve 21 is for controlling the B1 brake, the second solenoid valve 22 is for controlling the C2 clutch, and the third solenoid valve 22 is for controlling the C2 clutch.
The solenoid valve 23 serves both for controlling the C3 clutch and for controlling the B2 brake. The fourth solenoid valve 24 is in the L range (1
It is used for control during (speed) and transition of the R range. First to first
The third solenoid valves 21 to 23 perform delicate hydraulic control,
A duty control valve or a linear solenoid valve is used, and the fourth solenoid valve 24 is an ON / OFF switching valve. The hydraulic control device 7 may be provided with electromagnetic valves for lock-up control of the torque converter 3 and line pressure control in addition to the four electromagnetic valves 21 to 24 for shift control.

Next, an example of the stuffing control method according to the present invention will be described, for example, when the shift lever is switched from D to N to D, that is, when the state of the C2 clutch changes from engagement to disengagement to engagement. This will be explained. FIG. 4 shows a method of shortening the backlash time as the holding time (disengagement time of the C2 clutch) of the N range becomes shorter. Note that the vertical axis is the supply current to the second solenoid valve 22 that controls the C2 clutch,
The solenoid valve 22 is a normally open type. FIG. 4A shows a case where the holding time Tn is long, and the backlash time Tc is also long. That is, since the re-engagement is performed after the residual pressure in the immediately preceding engagement state is sufficiently released, even if the backlash time Tc is increased, a sudden engagement does not occur, and a shock can be avoided. On the other hand, FIG.
(B) shows a case where the holding time Tn is short, and the backlash time Tc is shortened. That is, since the re-engagement is started in a state where the residual pressure in the immediately preceding engagement state has not been sufficiently released, if the backlash time Tc is increased, a sudden engagement occurs as shown in FIG. Is generated. Here, by shortening the loosening time Tc, sudden engagement is prevented and shock is avoided.

FIG. 5 shows the relationship between the holding time Tn and the loosening time Tc. As shown in FIG. 5A, the holding time T
As the value of n increases, the play time Tc increases almost proportionally. Then, when the predetermined holding time Tno is exceeded, the loosening time Tc becomes the reference time Tco and becomes constant. The solid line in FIG. 5A shows the case where the holding time Tn and the stuffing time Tc are in a proportional relationship. As shown in (b), the gap time Tc is less than the predetermined holding time Tno.
May be set to 0, that is, backlash may be prohibited.

FIG. 6 shows a flow of the stuffing control method in which the stuffing time Tc is set shorter as the holding time Tn becomes shorter as shown in FIGS. When starting, it is first determined whether or not the shift lever has been switched from D → N → D or R → N → R (step S1). If the switching has been performed, the loosening of the predetermined frictional engagement element is started (step S2). For example, when switching from D → N → D, C
When two clutches are backlashed and R → N → R is switched, the B2 brake backlash is performed. Specifically, the controller 20 controls the current supplied to the second solenoid valve 22 or the third solenoid valve 23. Next, the holding time Tn of the N range is detected (step S3), and this holding time Tn is detected.
Is shorter than the set time Tno (step S4). If Tn ≧ Tno, the backlash time Tc =
Tco is set as Tco (step S5), and if Tn <Tno, as shown in FIG. 5, the backlash time Tc is set smaller according to Tn (step S6). Then, play is performed until the time Tc is up (Step S).
7) After the time is up, the engagement control of the friction engagement element is started (step S8), and the loosening control is ended.
In this way, by varying the loosening time Tc in accordance with the holding time Tn, it is possible to prevent both the engagement delay of the friction engagement element and the shock elimination.

FIG. 7 shows another embodiment of the rattling control according to the present invention, that is, the holding time (disengagement time of the C2 clutch) of the N range is detected, and the shorter the holding time, the lower the rattling oil pressure. Here's how to do it. FIG. 7A shows a case where the holding time Tn is long, and the backlash hydraulic pressure Pc is high. That is, since the re-engagement is performed after the residual pressure in the immediately preceding engagement state is sufficiently released, even if the backlash hydraulic pressure Pc is increased, sudden engagement does not occur, and a shock can be avoided. On the other hand, FIG.
(B) is a case where the holding time Tn is short, and the backlash hydraulic pressure Pc is also low. In other words, since re-engagement is started in a state where the residual pressure in the immediately preceding engagement state has not been sufficiently released, by reducing the backlash hydraulic pressure Pc, sudden engagement is prevented, and shock is avoided. ing. Thus, the holding time T
By varying the backlash hydraulic pressure Pc according to n, it is possible to prevent both the delay in engagement of the C2 clutch and the elimination of the shock.

FIG. 8 shows the relationship between the holding time Tn and the loosening oil pressure Pc. As shown in FIG. 8A, the holding time T
As the value of n increases, the play hydraulic pressure Pc also increases almost proportionally. Then, when the predetermined holding time Tno is exceeded, the backlash hydraulic pressure Pc becomes the reference pressure Pco and becomes constant. Note that the solid line in FIG. 8A is a case where the holding time Tn and the backlash hydraulic pressure Pc are in a proportional relationship. As shown in (b) of FIG.
May be set to 0, that is, backlash may be prohibited.

In the above description, the method of avoiding the garage shock due to the backlash has been described. However, even during traveling, in order to avoid the shift shock due to the backlash,
Similar control can be performed. When the speed change mechanism as shown in FIG. 2 is used, the following case can be considered as a control example of the present invention during traveling. (1) When the state of the C3 clutch changes from engagement to disengagement to engagement when upshifting again to third gear immediately after downshifting from third gear to second gear (2) Upshifting from third gear to fourth gear When the C2 clutch changes state from engagement to disengagement to engagement when downshifting again to third gear immediately after shifting (3) Upshifting to second gear again immediately after downshifting from second gear to first gear If the vehicle has been downshifted from 4th gear to 3rd gear and then upshifted again to 4th gear,
When the B1 brake changes state from engagement to release to engagement

The present invention is not limited to the above embodiment. In the above embodiment, three clutches C1 to C3 and 2
Although the automatic transmission having the brakes B1 and B2 has been described, the present invention is not limited to this, and is applicable to an automatic transmission having various frictional engagement elements. In the above-described embodiment, an example in which only one of the loosening time Tc and the loosening oil pressure Pc is changed based on the release time Tn has been described.
Both may be changed simultaneously. That is, the release time Tn
As the distance becomes shorter, both the clearance time Tc and the clearance oil pressure Pc may be set shorter (smaller).

In the above embodiment, the loosening time or the loosening oil pressure is set based on the release time. However, the loosening time or the oil pressure may be set in consideration of the oil temperature condition. In other words, when the ATF oil temperature is low, the fall of the oil pressure is slow, and the relationship between the holding time (disengagement time) and the engagement shock is different between when the temperature is high. Therefore, only when the oil temperature is lower than the set temperature, as in the present invention, as the holding time in the released state becomes shorter, the amount of stuffing is set smaller, or when the holding time in the released state is shorter than the set time. If filling is prohibited and the oil temperature is higher than the set temperature, the normal filling control (the filling time and the filling oil pressure are constant) may be performed. For example, in the case of the backlash control in FIG. 6, the oil temperature is determined before step S4. If the oil temperature is lower than the set temperature, the control from step S4 is performed. In this case, a normal play control is performed.

[0027]

As is apparent from the above description, claim 1
According to the invention described in the above, when the state of the friction engagement element changes from engagement to release to engagement, as the holding time of the released state becomes shorter, the amount of backlash at the time of re-engagement is reduced. Since it is set small, it is possible to reduce the shock at the time of re-engagement while eliminating the engagement delay. According to the second aspect of the present invention, if the release time is shorter than the set time, the backlash itself is prohibited. It is possible to achieve both a reduction in shock at the time of engagement and a simple control.

[Brief description of the drawings]

FIG. 1 is a system diagram in which an automatic transmission for a vehicle according to the present invention is mounted.

FIG. 2 is a skeleton diagram of a transmission mechanism of the automatic transmission of FIG.

FIG. 3 is an operation table of each friction engagement element and a solenoid valve of the transmission mechanism shown in FIG. 2;

FIG. 4 is a time change diagram of a current supplied to an electromagnetic valve as an example of the stuffing control according to the present invention.

FIG. 5 is a diagram illustrating a relationship between a play time and a holding time in FIG. 4;

FIG. 6 is a flowchart illustrating an example of play control.

FIG. 7 is a time change diagram of a supply current to a solenoid valve in another example of the stuffing control according to the present invention.

FIG. 8 is a diagram showing the relationship between the backlash hydraulic pressure and the holding time in FIG. 7;

FIG. 9 is a time change diagram of a supply current to an electromagnetic valve, a supply hydraulic pressure to a friction engagement element, and an output torque in the conventional play control.

[Explanation of symbols]

 C1 to C3 Clutch (friction engagement element) B1, B2 Brake (friction engagement element) 20 Controller 21 to 24 Solenoid valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J052 AA01 CA02 CA03 CA05 CA06 CA31 FB31 GC13 GC23 GC41 GC46 GC72 GC73 HA02 KA02 LA01

Claims (3)

[Claims] 1. A vehicle having a plurality of frictional engagement elements and selectively engaging the frictional engagement elements by supplying hydraulic pressure to the frictional engagement elements to achieve a plurality of shift speeds. In an automatic transmission, when a friction engagement element that achieves a predetermined gear position changes state from engagement to disengagement to engagement, a high oil pressure is supplied to the friction engagement element at the start of re-engagement. A method for controlling an automatic transmission for a vehicle, wherein the backlash is performed and the backlash amount is set to be smaller as the holding time of the release state becomes shorter. 2. A vehicle for a vehicle having a plurality of friction engagement elements and selectively engaging the friction engagement elements by supplying hydraulic pressure to the friction engagement elements to achieve a plurality of shift speeds. In the automatic transmission, when the friction engagement element that achieves the predetermined gear position changes state from engagement to disengagement to engagement, re-engagement starts when the holding time of the disengagement state is longer than a set time. A method for controlling an automatic transmission for a vehicle, characterized in that a high hydraulic pressure is supplied to the frictional engagement element and the loosening is performed, and the loosening is prohibited when the holding time of the released state is shorter than a set time. . 3. Only when the oil temperature of the automatic transmission is lower than a set temperature, the amount of looseness is set smaller as the release time of the release state becomes shorter, or the release time of the release state is shorter than the set time. 3. The control method for an automatic transmission for a vehicle according to claim 1, wherein the loosening of time is prohibited.