JP3236460B2 - Shift control device for automatic transmission for vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling a shift of an automatic transmission for a vehicle, and more particularly to a shift control device for an automatic transmission having an overdrive portion.

[0002]

2. Description of the Related Art Conventionally, in order to improve quietness and fuel efficiency during high-speed running, an automatic transmission configured to be able to set an overdrive stage with a gear ratio smaller than "1" has been frequently used. In order to correct the deterioration of fuel efficiency caused by the slip, a lock-up clutch that mechanically directly connects an input element (front cover) and an output element (turbine runner) has been used frequently. Since the overdrive stage in this type of automatic transmission needs to be able to be manually released, it is configured to be electrically controlled, and the forward stage is controlled by the governor pressure corresponding to the output shaft speed. The same applies to a hydraulic automatic transmission controlled based on the above. That is, in the conventional hydraulic automatic transmission, the solenoid valve is controlled using the throttle opening indicating the engine load and the output shaft rotation speed or the vehicle speed as parameters, and for example, the shift between the third speed and the fourth speed is controlled. I have.

On the other hand, the lock-up clutch is a clutch that mechanically directly connects the input element and the output element of the torque converter, so that when it is engaged, it also transmits vibration from the engine. In addition, since the input element and the output element rotate at the same rotational speed, the effect of amplifying the torque is eliminated. Therefore, conventionally, in general, the lock-up clutch is engaged at a speed higher than a predetermined speed such as the highest speed and at a vehicle speed higher than the predetermined speed. Such control is performed similarly in a hydraulic automatic transmission.Specifically, a lockup signal valve is operated by a governor pressure which is a pressure corresponding to the output shaft rotation speed,
Further, the lock-up relay valve is operated by the output pressure to engage / disengage the lock-up clutch (ON / OFF).
OFF).

[0004] An automatic transmission for performing this type of control is described in, for example, "Toyota Serviceman Technical Learning Third Step" (issued by Toyota Motor Corporation in October 1984). In this automatic transmission, the vehicle speed is approximately 57 km in the fourth speed (overdrive (O / D) cut is released).
/ H, the lock-up clutch is engaged (ON), and the vehicle speed is about 50 km in the fourth speed state.
/ H so that the lock-up clutch is released (OFF) when it falls below / h.

In the above-described conventional automatic transmission, the O / D cut is electrically controlled, and an example of a control map thereof is shown in FIG. This is a schematic diagram showing a shift diagram of the automatic transmission and a part of the control map of the lock-up clutch.
/ D cut execution line, and the broken line set on the lower throttle opening side is the O / D cut release line. Therefore, the O / D cut (downshift from the fourth speed to the third speed) is performed by changing the throttle opening from the lower side to the upper side of the O / D cut execution line. Conversely, the throttle opening changes from the upper side to the lower side of the O / D cut release line so that the O / D
Switching to state (upshift from third gear to fourth gear)
Is executed.

On the other hand, when the vehicle speed changes together with the O / D cut control based on such a change in the throttle opening, the change in governor pressure causes the ON / O of the lock-up clutch to change.
Control of FF (engagement / disengagement) is performed, and a map for this control is represented by the ON line and the OFF line in FIG. That is, when the vehicle speed increases so as to cross the ON line, the lock-up clutch is engaged, and conversely, O
When the vehicle speed decreases so as to cross the FF line, the lock-up clutch is released. In order to prevent hunting, a hysteresis is set between the ON line and the OFF line. As described above, the map for the O / D control shows that the O / D increases as the vehicle speed increases and the throttle opening increases.
An area is set. This means that if the vehicle speed is high (that is, the engine speed is high), the muffled sound will not be loud even at a high throttle opening, and the acceleration performance will be particularly insufficient. Because there is no.

[0007]

However, if the throttle opening is increased by depressing the accelerator pedal to accelerate the vehicle while traveling at the fourth speed, which is the O / D state, the traveling state becomes the third state shown in FIG. By entering the speed range, the control of the O / D cut is executed, and the gear shifts down to the third speed. As a result, a sufficient acceleration force is obtained by increasing the gear ratio, and when the vehicle speed increases, the accelerator pedal is returned to reduce the throttle opening. Then, the control for canceling the O / D cut is executed, and the upshift is performed to the fourth speed. Further, the lockup clutch is engaged by increasing the vehicle speed. That is, the reduction of the gear ratio due to the upshift and the cancellation of the torque increasing function of the torque converter due to the engagement of the lock-up clutch occur simultaneously.

[0008] In this case, in the above-mentioned conventional control device,
The fourth speed state in which the lock-up is ON is based on the fact that the map for O / D control is uniformly set to the upper right,
This is achieved before the vehicle speed is sufficiently increased, and as a result, the acceleration power becomes insufficient, and the accelerator pedal is depressed again, which causes a downshift to the third speed. In such a situation, when the lock-up is ON, the throttle opening is increased to downshift to the third speed, and thereafter, the throttle opening is decreased to change the lock-up ON to the O / D state (fourth speed). The same is true when returning, and again due to lack of acceleration force,
The downshift to the third speed is executed by depressing the accelerator pedal.

As described above, in the conventional shift control device, the O /
Since the condition of the throttle opening for the control of the D cut is the same regardless of ON / OFF of the lock-up clutch, after executing the O / D cut to accelerate,
When the throttle opening is reduced to release the control of the O / D cut, the acceleration force is insufficient, and the control of the O / D cut is required again, so that there is a problem that a so-called busy shift occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a shift control device capable of controlling overdrive suitable for lock-up ON and OFF, thereby improving acceleration and fuel efficiency. It is intended to provide.

[0011]

According to the present invention, a lock-up clutch for directly transmitting torque between an input element and an output element in a torque converter, and a high-low clutch can be switched. A shift control device for an automatic transmission, comprising: an overdrive section; and overdrive control means for controlling the overdrive section to be switched to a high-speed gear or a low-speed gear based on a map in which a value representing a running state is used as a parameter. A lock-up detecting means for detecting an engaged / disengaged state of the lock-up clutch; and, as the map, an up-shift line when the lock-up clutch is released and a throttle opening higher than the up-shift line. A first map having a downshift line and a lockup clutch engaged. In this case, a second map having a downshift line set between the upshift line and the downshift line and an upshift line set at a lower throttle opening degree than the upshift line is employed. And a map switching means.

[0012]

The shift control device according to the present invention has two maps for controlling the overdrive section: a map used when the lock-up clutch is engaged and a map used when the lock-up clutch is released. And two types of maps. The state of engagement / disengagement of the lock-up clutch is detected by lock-up detection means,
The map switching means selects a map suitable for the engagement / disengagement state of the lock-up clutch based on the detection result, and controls the overdrive unit according to the map.

The maps used when the lock-up clutch is engaged are different from those used when the lock-up clutch is disengaged in that the overdrive state is set to a low throttle opening. Therefore, when the throttle opening increases in the lock-up state, the overdrive state is released relatively early (O / D cut), and the speed ratio is increased to ensure the acceleration performance. . On the other hand, when the lock-up clutch is disengaged, a map is used as an overdrive region up to the high throttle opening side, so that the torque converter obtains the acceleration force by the torque amplifying action and delays the downshift. An increase in engine speed is suppressed, thereby improving fuel efficiency. Furthermore, if the vehicle shifts down due to overdrive cut control for acceleration and enters the lock-up region due to an increase in vehicle speed, upshifting due to overdrive cut release is unlikely to occur due to changes in the map used. Shortages are avoided. Since the downshift line of the map used in the lockup state is set to a higher throttle opening side than the upshift line of the map used in the state where the lockup clutch is disengaged, the map change Hunting is prevented.

[0014]

Next, the present invention will be described based on embodiments. The automatic transmission shown in FIG. 1 includes a torque converter 1 with a lock-up clutch, a third speed transmission unit 2 as a main transmission unit, and an overdrive (O / D) unit 3 as an auxiliary transmission unit.
And The torque converter 1 is conventionally known, and has a turbine runner 6 disposed opposite a pump impeller 5 integrated with a front cover 4 and a lock selectively engaged with the front cover 4. An up clutch 7 is connected to the turbine runner 6. Reference numeral 8 denotes a stator.
Is supported by a predetermined fixed portion via a one-way clutch 9.

Although the details of the three-speed transmission unit 2 are omitted, the three-speed transmission unit 2 is mainly composed of two sets of planetary gear mechanisms and a plurality of frictional engagement devices such as clutches and brakes. The gear is configured to be able to set three forward speeds and one reverse speed. The O / D unit 3 is disposed on the output side of the third-speed transmission unit 2 and mainly includes a set of a planetary gear mechanism, a clutch, and a brake. And can be set. These three-speed transmission unit 2 and O / D
The unit 3 has a conventionally known configuration.

The shift control in the automatic transmission is mainly performed by controlling a shift valve in the hydraulic control device 10 to a throttle pressure corresponding to a pressure corresponding to the throttle opening and a governor providing a pressure corresponding to the output shaft speed (ie, the vehicle speed). The switching operation is performed by pressure and the hydraulic pressure is supplied to and discharged from the hydraulic servo mechanism of each clutch or brake by the shift valve. Control of engagement / disengagement of the lock-up clutch 7 is performed by operating a lock-up signal valve (not shown) by governor pressure, and applying a hydraulic pressure output from the lock-up signal valve to a lock-up relay valve (not shown). This is executed by switching the direction of supply and discharge of the hydraulic pressure to the lock-up clutch 7 by feeding. A governor valve (not shown) for generating the governor pressure and a mechanism for controlling the lock-up clutch 7 can employ conventionally known mechanisms, and a detailed description thereof will be omitted.

The control of the O / D unit 3 is executed by the hydraulic pressure sent from the hydraulic control unit 10 as in the case of the third speed transmission unit 2, and the hydraulic pressure for that is electrically controlled by a solenoid valve (not shown). Controlled. For that purpose, an electronic control unit (T-ECU) mainly composed of a microcomputer
An electronic control unit 11 is provided with an electronic control unit (E-ECU) 12 for an engine.
The PD and the throttle opening TA are communicated as control data. Then, the electronic control unit 11 outputs a signal to the solenoid valve based on a control map provided in advance and the input data, and controls the O / D unit 3 to a high speed stage or a low speed stage.

As the control maps, two types of maps are provided according to the engaged / disengaged state of the lock-up clutch 7, and one example is schematically shown in FIG. This map uses the vehicle speed SPD on the horizontal axis and the throttle opening TA on the vertical axis.
And an O / D area (O / D cut release area: fourth speed area) and a non-O / D area (O / D cut area: third speed area) are set by these two parameters. is there. A map indicated by reference A is a map adopted when the lock-up clutch 7 is released (L / U OFF), and a map indicated by reference B engages the lock-up clutch 7 (L / U ON). ) Is the map that is adopted when the game is being performed.

Briefly explaining these maps A and B, each of them has upshift lines Au and Bu and downshift lines Ad and Bd, the lower side of these lines is the O / D area, and the upper side is the O / D area. This is an O / D cut area. The upshift lines Au and Bu are set on the lower throttle opening side than the downshift lines Ad and Bd, and the throttle opening TA changes so as to cross the upshift lines Au and Bu from the upper side to the lower side. O / D
The cut release control is executed to enter the O / D state. On the other hand, the O / D cut control is performed by changing the throttle opening TA so as to cross the downshift lines Ad and Bd from the lower side to the upper side, and the non-O / D state is established.
The ON line and the OFF line are the same as the ON line and the OFF line shown in FIG.

A downshift line Bd of the map B is set on the throttle opening side higher than the upshift line Au of the map A. This is to prevent hunting from occurring when the map is switched.

That is, in consideration of the muffled sound and acceleration when the lock-up clutch 7 is engaged, the map B is desirably set to a lower throttle opening degree, and its downshift line Bd is A is on the lower throttle opening side than the upshift line Au of A.

However, when the map B is set to the low throttle opening side in this manner, the accelerator pedal is returned while the vehicle is running in the O / D cut state to reduce the throttle opening TA.
Assuming that the traveling state crosses the downshift line Ad in the map A and the lock-up ON state occurs, the O / D cut control map is switched to the map B, and the traveling state is changed to the O / D cut in the map B. Enter the area. Therefore, immediately after the throttle opening degree TA changes across the upshift line Au of the map A and an upshift occurs, O /
D-cut control, that is, downshifting is performed, and a so-called busy shift occurs.

To prevent such inconvenience, the downshift line Bd of the map B is set to a higher throttle opening side than the upshift line Au of the map A.
As a result, when the throttle opening TA is decreased, it does not cross the downshift line Bd of the map B after crossing the upshift line Au of the map A, so that a downshift immediately after the upshift is prevented.

FIG. 3 shows a control routine for selecting the maps A and B. First, in step 1, it is determined whether or not the lock-up clutch 7 is engaged (ON) (lock-up ON). Specifically, this is determined by a control flag in predetermined control executed by the electronic control unit 11 for the automatic transmission. If the determination result is “No”, the process proceeds to step 2 and the vehicle speed SPD is
It is determined whether or not the lockup clutch 7 has exceeded the vehicle speed α in the engaged state. The reference vehicle speed α is, for example, the vehicle speed at which the ON line is set. If the result of the determination is "No", the process proceeds to step 3 and the map A is selected. On the other hand, if the result of the determination in step 1 or step 2 is “NO”, the process proceeds to step 4 and the map B is selected.

That is, if the lock-up clutch 7 is in the disengaged state and the vehicle speed is equal to or lower than the vehicle speed at which the lock-up clutch 7 is engaged, the map in which the upshift line and the downshift line are set to the high throttle opening side is set. O / D cut control is performed based on A. When the lock-up clutch 7 is in the engaged state, the O / D cut control is performed based on the map B in which the upshift line and the downshift line are set on the lower throttle opening side than the map A. Will be In the range of the hysteresis set between the ON line and the OFF line for controlling the lock-up clutch 7, the map A and the map B
When the lock-up clutch 7 is engaged, a downshift is performed based on the map A, and an upshift is performed based on the map B. Alternatively, a map or a shift line may be appropriately used.

Therefore, according to the above-described control, when the lock-up clutch 7 is released and the torque converter 1 performs a torque amplifying operation, the map in which the O / D cut control is set to a relatively high throttle opening degree is used. Therefore, the O / D cut or downshift caused by increasing the throttle opening TA is unlikely to occur. In other words, the overdrive state is maintained up to the relatively high throttle opening TA. As a result, the required acceleration force can be obtained by the torque amplifying action of the torque converter 1, and the engine speed can be suppressed to improve fuel efficiency.

When the lock-up clutch 7 is engaged, the O / D cut is controlled based on the map B set at a relatively low throttle opening.
When the accelerator pedal is depressed, O
Since the / D cut control is executed and a downshift occurs, and the lock-up clutch 7 is disengaged at the same time, a muffled sound caused by an increase in the throttle opening TA can be prevented.
In addition, sufficient acceleration can be secured. Further, if the O / D cut is controlled based on this map B, the O / D cut release or upshift accompanying the decrease in the throttle opening TA will result in a sufficient decrease in the throttle opening TA or a sufficient increase in the vehicle speed. Since there is a delay until a certain time, the vehicle speed cannot be maintained due to an upshift and lockup when the throttle opening TA is reduced after acceleration.

In the above embodiment, the hydraulic four-speed automatic transmission has been described as an example. However, the present invention is not limited to the above embodiment, and the electronically controlled automatic transmission is not limited to the above embodiment. The present invention can also be applied to the target shift control device.

[0029]

As explained above, according to the present invention,
Since the O / D cut is controlled in accordance with the engagement / disengagement state of the lock-up clutch, it is possible to prevent lack of acceleration due to delay of the O / D cut and muffled noise caused by the delay. It is possible to prevent an increase in the engine speed or an excessive acceleration force due to the O / D cut being too early, and to obtain an optimum acceleration feeling according to the engagement / disengagement state of the lock-up clutch as a whole. it can. In addition, since the engine is not excessively rotated or the throttle opening is not excessively increased, fuel efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating an example of a map for O / D cut control.

FIG. 3 is a flowchart showing an example of a control routine for switching the map.

FIG. 4 is a diagram schematically illustrating an example of a map for O / D cut control in a conventional control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torque converter 2 3rd speed change part 3 Overdrive part 4 Front cover 6 Turbine runner 7 Lockup clutch 11 Electronic control unit

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tohru Sato 117-2 Ikeshita, Yawata, Chita-shi, Aichi (56) References JP-A-3-117774 (JP, A) JP-A-4-277370 (JP, A JP-A-58-101830 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63 / 48

Claims (1)

(57) [Claims] 1. A lock-up clutch for directly transmitting torque between an input element and an output element of a torque converter, an overdrive section that can be switched between high and low, and a map using a value representing a running state as a parameter. A shift control device for an automatic transmission, comprising: an overdrive control unit that controls the lever to be switched to a high speed stage or a low speed stage; a lockup detection unit that detects an engaged / disengaged state of the lockup clutch; When the lock-up clutch is released, a first map having an upshift line and a downshift line set to a higher throttle opening degree than the upshift line is adopted as the map, Is engaged between the upshift line and the downshift line. A vehicle-mounted automatic switch comprising a second map having a fixed downshift line and an upshift line set at a lower throttle opening than the upshift line. Transmission control device for transmission.