JP3139449B2 - 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, and more particularly to a shift control device for preventing an interlock occurring at a low temperature in a manual 1-> 2 shift.

[0002]

2. Description of the Related Art Automatic transmissions are known, for example, from Nissan Motor Co., Ltd.
Issued in March 1987, "NISSAN RE4R
01A Full-range electronically controlled automatic transmission maintenance manual ”(A261C07), a plurality of clutches, brakes, and other frictional elements are selectively selected in the forward range of the manual valve operated by the driver using the shift lever. The power transmission path (gear stage) of the gear transmission system is determined by hydraulically operating (fastening), and power can be transmitted from the input shaft to the output shaft at the selected gear stage, and the friction element to be operated is switched. Thus, a shift to another shift speed is performed. Therefore, the automatic transmission has a shift that is performed by replacing a friction element, switching one friction element from a engaged state to a released state, and switching another friction element from a released state to a engaged state. The shift performed by changing is
In the case of an automatic transmission having a manual shift range, the automatic transmission is not limited to the automatic shift, and is present at the time of manual shift.

[0003] By the way, the supply of the operating pressure to the engagement-side friction element to be switched to the above-mentioned engagement state supplies the hydraulic oil in a pressurized state. Since the operation pressure is removed from the release-side friction element to be switched to the release state by drainage, the operation pressure tends to be greatly delayed at low temperatures when the viscosity of the hydraulic oil increases. FIG. 9 shows the operation at the low temperature.
In addition, the operating pressure (fastening pressure) of the friction element on the fastening side
Respect to the time required for P _ON is raised to a value such to start engagement of the frictional element from the shift command instant t ₀ is the relatively short as TM _1, operating pressure (release pressure of the release side frictional element )
P _OFF time becomes longer as the TM ₂ needed to drop to a value to start the release of the friction element from the shift command instant t _0, the increase of the reduced engagement pressure P _ON the release pressure P _OFF Be late. This low temperature because, during the period ΔTM from engagement start instant t ₁ of the engagement side frictional element to the release initial instant t ₂ of the disengagement side frictional element, it is possible to both friction elements is engaged simultaneously, during which the automatic transmission The gear transmission train of the machine is set in an interlock state, and during the shift change at a low temperature, a large torque is generated as shown by hatching in the transmission output torque (T _o ) waveform of FIG. The shift quality is reduced, and the commercial value of the automatic transmission is reduced.

[0004] Regarding such shifting at low temperatures, it has been conventionally proposed to prohibit or invalidate all manual shifting at low temperatures, as described in JP-A-8-233077. The aim is that in a manual shift, the driver issues a shift command, so that the driver can intuitively know the shift response delay from the shift command to the time when the shift is actually performed. When the manual shift is permitted, the driver realizes that the responsiveness of the shift has deteriorated due to the increase in the viscosity of the hydraulic oil due to the low temperature, and avoids the adverse effect that the driver may feel uncomfortable at the time of the manual shift. That's why.

[0005]

However, such a conventional measure can solve the above-mentioned problems relating to the interlock and the accompanying torque pull-in under a low temperature condition which occur during manual gear shifting. Since the manual transmission is completely prohibited or invalidated, the automatic transmission with the manual transmission range added is prohibited or invalidated even at the time of the manual transmission that does not cause the above-described problem regarding the torque pull-in. Will be halved in commercial value.

A first aspect of the present invention is intended to solve the above-mentioned problem relating to the torque pull-in under a low temperature condition during manual gear shifting. Switching from the engaged state to the disengaged state, switching the second-speed selection friction element from the disengaged state to the engaged state, replacing the friction element, and taking measures during a manual 1 → 2 shift,
At this time, it is proposed to propose a shift control device for an automatic transmission which can solve this problem without sacrificing a manual shift at all, even though shift response delay becomes a problem at extremely low temperatures. Aim.

A second aspect of the present invention is intended to solve the above-mentioned problem relating to the pull-in of torque under a low temperature condition at the time of a manual 1 → 2 shift. To provide a shift control device for an automatic transmission which can solve the problem by only sacrificing the manual 1 → 2 shift, although the shift response delay becomes a problem at extremely low temperatures. With the goal.

[0008]

SUMMARY OF THE INVENTION For these purposes, a shift control device for an automatic transmission according to a first aspect of the present invention switches a friction element for engine braking from an engaged state to a disengaged state and sets a friction element for selecting the second speed. In an automatic transmission having a shift including a manual 1 → 2 shift performed by switching from a disengaged state to a engaged state and by changing a friction element, the operating pressure from an engine brake friction element to be switched to the disengaged state is determined. At a low temperature when the drain enters an interlock state with a delay with respect to the supply of the operating pressure to the second-speed selection friction element to be switched to the engagement state, the supply of the operating pressure to the second-speed selection friction element is performed by the automatic transmission. The hydraulic oil temperature is lower, the interlock is prevented by delaying the hydraulic oil temperature, and the delay relating to the supply of the operating pressure to the friction element for selecting the second speed is performed. In the extremely low temperature region where the interval is equal to or longer than the set time, instead of delaying the supply of the operating pressure to the second speed selection friction element, the engagement of the engine brake friction element is prohibited even at the first manual speed. It is characterized by having comprised.

A shift control device for an automatic transmission according to a second aspect of the present invention is a gear shift control device for switching a friction element for engine braking from an engaged state to a disengaged state and for switching a friction element for selecting the second speed from the disengaged state to the engaged state. In an automatic transmission having a shift including a manual 1 → 2 shift, a drain of an operating pressure from an engine brake friction element to be switched to the released state is selected by selecting a second speed to be switched to the engaged state. At a low temperature when the interlock state is delayed with respect to the supply of the operating pressure to the friction element, the supply of the operating pressure to the friction element for selecting the second speed is delayed longer as the hydraulic oil temperature of the automatic transmission is lower. In the extremely low temperature region where the delay time related to the supply of the operating pressure to the second speed selection friction element is equal to or longer than a set time, the interlock is prevented. (2) Instead of delaying the supply of the operating pressure to the friction element for selecting the second speed, the manual first speed is prohibited from being selected, and only the second or higher speed is manually selected. It is characterized by the following.

[0010]

The automatic transmission switches the friction element for engine braking from the engaged state to the released state and switches the friction element for selecting the second speed from the released state to the engaged state.
In a manual 1 → 2 shift performed by replacing the friction element, the shift control device according to the first aspect of the present invention is configured such that the drain of the operating pressure from the engine brake friction element to be released is transferred to the second speed selection friction element to be engaged. The supply of the operating pressure to the second-speed selecting friction element is delayed longer when the operating oil temperature of the automatic transmission is lower, at a low temperature when the interlock state is delayed with respect to the supply of the operating pressure. The interlock can be reliably prevented at each temperature, and the problem of torque pull-in which has conventionally occurred due to this can be surely solved. In addition, the manual 1 → 2 shift has a large gear ratio, and the problem of the interlock at a low temperature becomes more remarkable than other manual shifts.

According to the above, when the operating oil temperature becomes extremely low, the delay time relating to the supply of the operating pressure to the second speed selecting friction element becomes longer than the set time, causing a large shift response delay which is problematic. Will be. In other words, the driver manually issues a shift command and can know the shift response delay intuitively. Therefore, the driver may recognize the shift response delay that has increased as described above so as not to match the purpose of the manual shift. I feel uncomfortable. By the way, in the first invention, in the extremely low temperature region, instead of delaying the supply of the operating pressure to the friction element for selecting the second speed, the engagement of the friction element for engine braking is prohibited even in the manual first speed. Even at a very low temperature, the shift response delay does not become a problem, and this problem can be solved.

Also, even if the engagement of the friction element for engine braking in the first manual speed is prohibited, only the engine braking is not effective, and the manual shift itself selects all the gears including the first speed. It remains possible, there is no sacrifice of manual shifting, and the problem associated with the shift response delay can be resolved without any sacrifice of manual shifting. Further, as described above, prohibiting the engagement of the friction element for engine braking in the first manual speed means that the manual 1 → 2 shift is replaced with the shift, and no interlock is generated. Problems associated with interlocks can be eliminated without sacrificing any manual shifting.

In the second aspect of the present invention, instead of delaying the supply of the operating pressure to the second-speed selecting friction element in the extremely low temperature region where a problematic large shift response delay occurs, the first manual operation is performed. Since the speed is prohibited from being selected and only the second speed or higher is manually selected,
The manual 1 → 2 shift itself, in which the above-mentioned problem relating to the interlock (torque pull-in) under a low temperature condition at the time of manual shifting is most pronounced, is eliminated, and this effect can be solved. This can be achieved in such a mode that only the sacrifice of the first speed is achieved, and that a large shift response delay that does not match the purpose of the manual shift occurs.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a control system of an automatic transmission including a shift control device for an automatic transmission according to an embodiment of the present invention, wherein 1 is an engine, 2 is a torque converter, 3 is an automatic transmission, and engine rotation is torque. The power is transmitted to the input shaft 4 of the automatic transmission via the converter 2.

The automatic transmission 3 is basically the same as that described in the aforementioned "RE4R01A Automatic Transmission Maintenance Manual" (A261C07) issued by Nissan Motor Co., Ltd. A front planetary gear set 6 and a rear planetary gear set 7 are mounted on the shafts 4 and 5. The forward clutch F / C, high clutch H / C, band brake B / B, low reverse brake LR / B, low one-way clutch L / OWC,
And a reverse clutch R / C, and selectively engaging these as shown by a circle in FIG.
It is assumed that the reverse gear can be selected from the first to fourth speeds.
Note that the symbol (○) in FIG. 2 relating to the low reverse brake LR / B indicates that the engine is to be engaged when the engine brake is required at the first speed (when the driver selects an engine brake range L described later).

In this embodiment, in order to execute the selective operation (engagement) of the friction element, a duty solenoid for the forward clutch F / C is inserted particularly in the control valve 8 of the automatic transmission 3. 9, a duty solenoid 10 for a high clutch H / C, a duty solenoid 11 for a band brake B / B, a duty solenoid 12 for a low reverse brake LR / B, and a duty solenoid 1 for a reverse clutch R / C.
3 is provided. The automatic transmission 3 implements the engagement logic shown in FIG. 2 by individually duty controlling the operating hydraulic pressures of the corresponding friction elements by the duty solenoids 9 to 13, thereby realizing the automatic and manual forward first speed. To 4th speed and automatic reverse gear position can be selected.

The duty control of the solenoids 9 to 13 is performed by a controller 14, which includes a selection range selected by a driver using a shift lever 15, and a manual gear shift described later generated by the driver using the shift lever 15. A signal from the selector switch 16 for detecting a command and the throttle opening TVO of the engine 1
, A signal from a vehicle speed sensor 18 for detecting the vehicle speed VSP, and a signal from an oil temperature sensor 19 for detecting the transmission working oil temperature T _OIL .

The supplementary explanation of the shift lever 15 and the selector switch 16 is as follows. The shift lever 15 has a well-known parking (P) range position as described in the above-mentioned document.
A reverse (R) range position, a neutral (N) range position, an automatic forward shift (D) range position, and an engine brake (L) range position are arranged in a straight line, and are offset from the straight line. Manual shift (M)
It has a range position.

The selector switch 16 is connected to the shift lever 1
It is assumed that a signal indicating which of the range positions 5 is operated is output to the controller 14. While the shift lever 15 is in the manual shift (M) range position, it is supported in a self-returning manner between an upshift (+) position and a downshift (-) position. Each time the upshift to the step high speed side is desired, the shift lever 15 is set to the upshift (+) position,
The shift lever 15 is set to the downshift (-) position every time a downshift to the one-step low speed side is desired.
Every time is shifted to the upshift (+) position or the downshift (-) position, a manual shift command for the upshift or downshift is output to the controller 14.

The controller 14 executes the following shift control based on the input information. P range, R range,
In the N range, D range and L range, the controller 14
Performs substantially the same shift control as in the above document,
Through the duty control of the solenoids 9 to 13, the friction elements are individually engaged according to the engagement logic of FIG. Where L
The range is described as one range in the literature.

To explain automatic shifting in the D range, the controller 14 executes a control program (not shown) to
For example, based on the shift map shown in the above-mentioned document, a suitable shift speed required in the current operating state is searched from the throttle opening TVO and the vehicle speed VSP. Next, the controller 14 determines whether or not the currently selected shift speed matches the preferred shift speed. If the current shift speed does not match, the controller 14 executes the shift to the preferred shift speed, that is, the shift speed based on the engagement logic table of FIG. Duty control of the corresponding solenoids 9 to 13 is performed so that the engagement and release switching of the friction element is performed. Of course, if the currently selected shift speed matches the preferred shift speed, the controller 14 controls all of the solenoids 9 to 9.
13 is maintained at the current duty, and the current selected shift speed is maintained.

To explain the manual shift in the M range, the controller 14 controls the shift switch 15 to the upshift (+) position or the downshift (-) position each time the shift lever 15 is shifted to the upshift manual shift from the selector switch 16. In response to the command or the downshift manual shift command, the engagement and disengagement switching of the friction element for upshift or downshift based on the currently selected shift speed is performed based on the engagement logic table in FIG. The duty of the corresponding solenoids 9 to 13 is controlled.

In the M range for the manual shift, the low reverse brake LR / B is engaged in the first speed as shown by (○) in FIG. In the D range, the low reverse brake LR / B is not engaged in the first speed (engaged in the engine brake range L), and the engine brake is not effective. Therefore, M
At the time of manual 1 → 2 shift in the range, the low reverse brake LR / B is released and the band brake B
/ B to be fastened, and the replacement of the friction element is required.
At the time of the automatic 1 → 2 shift in the range, since the low reverse brake LR / B is in the released state, the shift is performed only by engaging the band brake B / B.

For this reason, in the present embodiment, the low-temperature interlock countermeasures according to the present invention are applied to the manual 1-> 2 shift in the M range in which the replacement of the friction element is required. FIG. 3 shows only a portion of the shift control circuit relating to the low reverse brake LR / B and the band brake B / B involved in the shift, extracted from FIG. 1, and shows the operating pressure circuit 21 of the low reverse brake LR / B. And a pressure regulating valve 24 inserted into the operating pressure circuit 23 of the band brake B / B. The pressure regulating valves 22 and 24 use the line pressure P _L as the original pressure, and
Operation of the low reverse brake LR / B in response to an increase in the control pressure in the 24a pressure P _C and the band brake B
The operating oil pressure P _B of / B is individually increased from 0.

The control pressures in the chambers 22a and 24a of the pressure regulating valves 22 and 24 are respectively set to the corresponding solenoids 1 and 2.
2 and 11, these solenoids 1
2,11 is the source pressure constant pilot pressure P _p that created the line pressure P _L under reduced pressure, and supplies the control pressure according to the driving duty of the solenoid 12 and 11 chambers 22a, to 24a. Here, when the drive duty is 0%, the solenoids 12 and 11 do not supply the control pressure to the chambers 22a and 24a.
As a result, the operating oil pressure P of the low reverse brake LR / B
The hydraulic pressure P _{B C} and the band brake B / B to 0, and these friction elements in the released state, when the drive duty is 100%, the chamber 22a, the same maximum value as the pilot pressure P _p the control pressure to the 24a And the low reverse brake L
The hydraulic pressure P _B of the hydraulic pressure P _C and the band brake B / B in the R / B at the same maximum value as the line pressure P _L, shall these friction elements to the fastening state.

Before describing the present embodiment, a basic countermeasure against low temperature interlock performed by the controller 14 will be described first with reference to FIG. In the first step 31,
Manual 1 in the M range to take the interlock measure
→ It is determined whether or not a 2-shift command has been issued. If there is a manual 1 → 2 shift command, the drive duty of the solenoid 12 is set to 0% in step 32 at the moment of the shift command,
Low reverse brake LR / B of the hydraulic pressure P _C of the drain, that is commanding the release of the low reverse brake LR / B.

Next, at step 33, FIG.
The start delay TM ₁ of the engagement of the band brake B / B illustrated in FIG.
And delay T for releasing the low reverse brake LR / B
A delay time difference .DELTA.TM _D between M _2, obtained by the search from the transmission hydraulic oil temperature T _OIL as the band brake engagement command delay time. Here, FIG. 7 band brake B / engagement start delay TM ₁ and releasing the start delay TM ₂ of the low reverse brake LR / B and B illustrated in (a) are those obtained in advance by experiment for each oil temperature T _OIL the latter release starting delay TM ₂ is longer than the engagement start delay TM ₁ of the former, in the low temperature region of less than the oil temperature T ₂ shown by hatching, while the delay time difference .DELTA.TM _D between both the band brake B / B and the low reverse brake LR / B are both engaged at the same time, and the drag phenomenon of the interlock described above with reference to FIG. 9 occurs. Note that the lower the oil temperature T _OIL is, the longer the delay time difference ΔTM _D becomes.
The drag phenomenon of the interlock occurs for a long time.

As a result, in practice, FIG.
A delay time difference .DELTA.TM _D between released starting delay TM ₂ of engagement start delay TM ₁ and the low reverse brake LR / B of the band brake B / B for example (a), the band brake fastened as shown in FIG. (B) It is determined as the command delay time, and based on this, the transmission operating oil temperature T _OIL
And to find the band brake engagement command delay time ΔTM _D from. In the case where even without precisely determine the band brake engagement command delay time .DELTA.TM _D predetermined low temperature interlock preventing effect is obtained, the band brake engagement command delay time .DELTA.TM _D as shown in FIG. 7 (c) The determination may be performed in a stepwise manner. In this case, the memory capacity is small and the cost is advantageous.

[0029] In step 34, 35 in FIG. 4, the elapsed time from the manual 1 → 2 shift command while measured by the timer t, whether the elapsed time t has reached the band brake engagement command delay time .DELTA.TM _D When it is determined that the solenoid 11 has been reached, at step 36, the solenoid 11
Of the band brake B /
A command to increase the operating pressure PB of _B , that is, to apply the band brake B / B. Finally, in step 37, the timer t is reset to prepare for the next control.

The above-described manual 1 → 2 shift according to the control at the command time, the low reverse brake by solenoid 12 instantly t ₀ of the shift command, as shown in FIG. 8 is ON → OFF switching LR / working pressure P _C of B begins to decrease in real low reverse brake LR / elapsed instant t ₂ the low reverse brake L release starting delay TM ₂ of B
R / B starts release. Then, the instant t ₁ at which the band brake engagement command delay time .DELTA.TM _D has elapsed since the shift command instant t _0, the solenoid 11 begins to rise the operating pressure P _B of the band brake B / B by being OFF → ON switching, the band brake B / band brake B / B to the elapsed instant t ₂ of the engagement start delay TM ₁ of B is starting to engage.

By the way, as shown in FIG. 7, the band brake engagement command delay time ΔTM _D is such that the engagement start delay TM ₁ of the band brake B / B and the low reverse brake LR /
Since it is a delay time difference between the release start delay TM ₂ of B, even the transmission hydraulic oil temperature T _OIL is a low temperature region lower than T ₂ shown in FIG. 7, the release of the low reverse brake LR / B, a band The same instant t as the application of the brake B / B
₂ can be started, and the period in which both friction elements are fastened together can be eliminated to avoid the occurrence of an interlock state. Therefore, manual 1 →
That the retraction of torque accompanying the interlock is generated at the time of second speed change, can be prevented reliably as is apparent from the waveform of the transmission output torque T _o shown in FIG. 8, improving the shift quality of an automatic transmission In this way, the commercial value can be increased.

It should be noted that in step 31 of FIG.
→ If it is determined that there is no 2 shift command, in step 38, the above-described normal shift control is executed irrespective of the automatic shift and the manual shift.

The shifting by changing the friction element is not limited to the manual 1-> 2 shifting, and as is apparent from the engagement logic table of FIG. 2, the shifting of the band brake B / B and the high clutch H / C is performed. There are also automatic and manual 2-3 shifts performed by switching, and automatic and manual 3-4 shifts performed by changing the band brake B / B and the forward clutch F / C. Even in these shifts, an interlock is performed in a low temperature region. Tend to occur. However, in practice, since the gear ratio is small in the 2-3 shift and the 3-4 shift, the pull-in of the torque by the interlock is small, so that there is almost no problem. I confirmed that it was almost unnecessary.

In the manual shifting, the driver issues a shift command by operating the shift lever 15, so that the driver can intuitively know a shift response delay from the operation to the time when the shift is actually started. If the start of engagement of the band brake B / B is delayed in the low temperature region by the above-described measure, the driver will feel a shift response delay caused by the delay. Thus, for example, in very cold regions of the set oil temperature T less than ₁ provided a large band brake engagement command delay time than shown in .DELTA.TM _DS in FIG. 7 (a), feel that the driver is inconsistent with the spirit of the manual transmission Since the shift response delay is so long as to occur, in the present invention, for example, the low-temperature interlock countermeasures shown in FIGS. 5 and 6 are performed instead of the low-temperature interlock countermeasures shown in FIG.

Hereinafter, an embodiment of the present invention shown in FIGS. 5 and 6 will be described. FIG.
Indicates shift control based on the determination result. In step 41 of FIG. 5, FIGS. 7 (a) based on the fluid temperature T _OIL is whether the band brake engagement command delay range between T ₁ through T ₂ and whether the oil temperature T _OIL is T ₂ or more non-control region , the oil temperature T _oIL is determined band or brake engagement command delay prohibition area of less than T _1. In step 42, in accordance with the determination result, if the band brake engagement command is in the delay range, the control proceeds to step 43; if it is in the non-control range, the control proceeds to step 44; Proceed.

In step 43 selected in the band brake engagement command delay range, the oil temperature T is determined based on FIG.
_A corresponding band brake engagement command delay time ΔTM _D is retrieved from the _OIL , and in step 44 selected in the non-control region, the band brake engagement command delay time ΔTM
_D is unconditionally set to 0, and in steps 45 and 46 selected in the band brake engagement command delay prohibition area, the following control instead of the band brake engagement command delay control is performed.

That is, it is determined in step 45 whether or not the motor is in the M range. If the motor is in the M range, in step 46, the duty of the solenoid 12 is set to 0% so that the low reverse brake LR / B is kept in the released state, Although the engine brake is not effective at the first speed, the M range is set even if the application of the low reverse brake LR / B is substantially prohibited or the driver manually issues a downshift to the first speed. The first speed in the M range is prohibited so that the controller 14 does not instruct the first speed itself. If it is determined in step 45 that the current range is not the M range, step 46 is skipped, control is terminated, and the above processing is not performed.

In FIG. 6, which is executed based on the above-described processing of FIG. 5, first, at step 51, it is determined whether or not a manual 1 → 2 shift command in the M range in which countermeasures for low temperature interlock should be taken. . If there is a manual 1 → 2 shift command, it is determined in step 52 whether or not the range is a band brake engagement command delay prohibition range. If it is not the band brake engagement command delay prohibition range, that is, if it is the band brake engagement command delay range or the non-control range, in step 53, the solenoid 1
The second driving duty is 0%, the low reverse brake LR / B of the hydraulic pressure P _C of the drain, that is commanding the release of the low reverse brake LR / B immediately.

Next, in steps 54 and 55, the elapsed time from the manual 1 → 2 shift command is measured by the timer t, and the elapsed time t is determined by the band brake engagement command delay time obtained in step 43 or 42 in FIG. ΔT
Determines whether leading to M _D, in step 56 when determined that led, the driving duty of the solenoid 11 1
100% to increased operating pressure P _B of the band brake B / B are, that commands the engagement of the band brake B / B. Finally, at step 57, the timer t is reset to prepare for the next control.

According to the manual 1 → 2 shift control in the band brake engagement command delay range or the non-control range, as shown in FIG. 8, the solenoid 12 is turned on at the instant t _{0 of the} shift command.
N → working pressure P _C of the low reverse brake LR / B by being OFF switching begins to decrease in real low reverse brake LR / elapsed instant t release starting delay TM ₂ of B
_{At 2} the low reverse brake LR / B starts releasing.
Then, in an instant t ₁ the band brake engagement command delay time ΔTM _D has elapsed from the shift command instant t _0, solenoid 1
1 is switched from OFF to ON, the operating pressure PB of the band brake B / _B starts to increase, and the band brake B / B
The band brake B / B to start fastened to the elapsed instant t ₂ of the engagement start delay TM ₁ of B.

As shown in FIG. 7 (b), the band brake engagement command delay time ΔTM _D is such that the band brake B / B engagement start delay TM ₁ and the low reverse brake LR / B are released as shown in FIG. 7 (a). since delay is the time difference between the start delay TM _2, the transmission operating oil temperature T _oIL
In the low temperature region between T _{1 and} T ₂ shown in FIG. 7, the release of the low reverse brake LR / B and the release of the band brake B /
B can be started at the same instant t ₂ ,
An interlock state can be avoided by eliminating the period during which both friction elements are fastened together. Therefore,
From the manual 1 → 2 torque accompanying the interlocking at the time of shifting in a low temperature range pull occurs, it is possible to reliably prevented As is apparent from the waveform of the transmission output torque T _o shown in FIG. 8, The shift quality of the automatic transmission can be improved to increase its commercial value.

If it is determined in step 52 that the range is the band brake engagement command delay prohibition area, step 53
47 is skipped, and the duty of the solenoid 11 is immediately set to 100% in step 58, so that the command for engaging the band brake B / B is issued simultaneously with the manual 1 → 2 shift command, and then the control is terminated. However, in the band brake engagement command delay prohibition range, in the case of the M range, FIG.
In step 46, since the low reverse brake LR / B is maintained in the released state by the duty of the solenoid 12 being 0%, the manual 1 → 2 shift is performed only by the engagement of the band brake B / B as is apparent from FIG. And the shift is not a shift, and the problem of interlock at low temperatures does not occur. Therefore, even in the extremely low temperature region where the oil temperature T _OIL is lower than T _{1 in} FIG.
It is possible to prevent the torque from being pulled in by the interlock at the time of the second shift.

The countermeasure against the interlock in the extremely low temperature range is that the low reverse brake LR in the M range is used.
/ B is kept in the released state, the engine brake is not effective in the first speed of the M range, but all the first to fourth speeds can be selected in the M range.
In addition to taking measures against the interlock without sacrificing the M range shift speed at all, the following unique effects can be obtained.

That is, even in the extremely low temperature region, when the interlock countermeasures are taken by delaying the band brake engagement command as in the low temperature region, the delay time ΔTM of the band brake engagement command is apparent as shown in FIG. _D
Becomes extremely long, and the shift response delay from when the driver manually issues the shift command by himself to when the 1 → 2 shift is actually started becomes so long as to be incompatible with the purpose of the manual shift, causing an uncomfortable feeling. However, according to the countermeasure for keeping the low reverse brake LR / B in the released state as in the present embodiment, it is possible to avoid the interlock at a very low temperature without causing such discomfort. Incidentally, since the driver does not issue a shift command at the time of automatic shifting, it is not possible to know when the shift command is issued, and the driver does not feel a shift response delay and does not feel uncomfortable.

As described above with reference to step 46 in FIG. 5, in a very low temperature region (band brake engagement command delay prohibition region) where the oil temperature T _OIL is lower than T _{1 in} FIG. Even if there is a downshift command to the first speed, the first speed itself in the M range is
In the M range,
By prohibiting the speed, the manual 1 → 2 shift itself is eliminated, so that it is possible to avoid the interlock at an extremely low temperature without causing an uncomfortable feeling that the shift time becomes so long as to be incompatible with the purpose of the manual shift. it can. In this case, the first speed in the M range disappears, but the other speeds in the M range remain, so the problematic first speed is established.
It is possible to take countermeasures for interlock at extremely low temperatures only by sacrificing.

When it is determined in step 51 in FIG. 6 that there is no manual 1 → 2 shift command, in step 59, the above-described normal shift control is executed irrespective of the automatic shift and the manual shift.

[Brief description of the drawings]

FIG. 1 is a shift control system diagram of an automatic transmission including a shift control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing engagement logic of a friction element in the automatic transmission.

FIG. 3 is a system diagram showing, in the automatic transmission, a hydraulic circuit portion particularly related to control of the present invention.

FIG. 4 is a flowchart showing a shift control program for a low-temperature interlock countermeasure to be executed by a controller in the embodiment.

FIG. 5 is a flowchart showing an area determination program for a low-temperature interlock countermeasure according to another embodiment of the present invention.

FIG. 6 is a flowchart showing a shift control program for a low-temperature interlock countermeasure according to the embodiment.

7 (a) is a diagram showing the change characteristics of the delay in starting the release of the low reverse brake and the delay in starting the engagement of the band brake with respect to the oil temperature in FIGS. 1 and 3, and FIG. 7 (b) shows the band used in the present invention. FIG. 7C is a change characteristic diagram of a brake engagement command delay time, and FIG. 7C is a change characteristic diagram showing another form of the band brake engagement command delay time.

FIG. 8 is a time chart showing a time-series change in friction element operating oil pressure and transmission output torque when a band brake engagement command is delayed in the present invention.

FIG. 9 is a time chart similar to FIG. 8, showing how an interlock occurs when the automatic transmission shifts at a low temperature.

[Explanation of symbols]

 1 Engine 2 Torque converter 3 Automatic transmission 4 Input shaft 5 Output shaft 6 Front planetary gear set 7 Rear planetary gear set 8 Control valve 9 Duty solenoid 10 Duty solenoid 11 Duty solenoid 12 Duty solenoid 13 Duty solenoid 14 Controller 15 Shift lever 16 Selector switch 17 Throttle opening sensor 18 Vehicle speed sensor 19 Oil temperature sensor 22 Pressure regulator 24 Pressure regulator F / C Forward clutch B / B Band brake (friction element for selecting 2nd speed) H / C High clutch LR / B Low reverse brake (release friction) Element) R / C reverse clutch

Claims (2)

(57) [Claims] 1. A manual 1 → 2 shift operation in which an engine brake friction element is switched from an engaged state to a released state, and a second speed selecting friction element is switched from an released state to an engaged state. In the automatic transmission having a shift including: the operation pressure drain from the engine brake friction element to be switched to the release state is controlled by the supply of the operation pressure to the second speed selection friction element to be switched to the engagement state. At a low temperature when the interlock state is delayed, the supply of the operating pressure to the second-speed selection friction element is delayed longer as the hydraulic oil temperature of the automatic transmission is lower to prevent the interlock, In a very low temperature region where the delay time related to the supply of the operating pressure to the second speed selecting friction element is equal to or longer than a set time, the supply of the operating pressure to the second speed selecting friction element is stopped. Instead of cast, shift control apparatus for an automatic transmission which is characterized by being configured so that manual first speed even for engine brake friction element is inhibited from being fastened. 2. A manual 1 → 2 shift operation in which a friction element for engine braking is switched from a engaged state to a released state, and a friction element for selecting second speed is switched from a released state to an engaged state. In the automatic transmission having a shift including: the operation pressure drain from the engine brake friction element to be switched to the release state is controlled by the supply of the operation pressure to the second speed selection friction element to be switched to the engagement state. At a low temperature when the interlock state is delayed, the supply of the operating pressure to the second-speed selection friction element is delayed longer as the hydraulic oil temperature of the automatic transmission is lower to prevent the interlock, In a very low temperature region where the delay time related to the supply of the operating pressure to the second speed selecting friction element is equal to or longer than a set time, the supply of the operating pressure to the second speed selecting friction element is stopped. Instead of cast, manually manually first speed is inhibited from being selected shift control apparatus for an automatic transmission which is characterized by being configured so that only gear position above the second speed is selected.