JP3029265B2 - Control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for an automatic transmission having a lock-up mechanism.

2. Description of the Related Art Conventionally, an automatic transmission having a lock-up mechanism for improving transmission efficiency by directly connecting an input side and an output side of a torque converter under a predetermined condition has been employed, and a normal deceleration state has been adopted. In the above, the lock-up mechanism controls to release the engaged state.

However, in the downhill running state, etc., since the engine brake is less effective in the CD range of the automatic transmission, the lock-up mechanism is operated in the engaged state while the foot brake is frequently used. A technique for enhancing the effectiveness of an engine brake is known, for example, as disclosed in JP-A-60-60368.

(Problems to be Solved by the Invention) However, when the lock-up mechanism is engaged during deceleration as described above to increase the effectiveness of the engine brake, the effectiveness of the engine brake due to the engagement of the lock-up mechanism is increased. When the vehicle is traveling on a steep downhill, the operation of the lock-up mechanism alone is insufficient for the engine brake, and the vehicle speed is likely to further increase.

On the other hand, when the automatic transmission is downshifted during deceleration as described above, the effect of the engine brake becomes very large, and is effective during rapid deceleration, but deceleration shock occurs when performing downshift during normal deceleration. Have problems.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a control device for an automatic transmission in which the effectiveness of an engine brake is changed according to the deceleration at the time of deceleration.

(Means for Solving the Problems) In order to achieve the above object, a control device for an automatic transmission according to the present invention comprises an automatic transmission A as shown in the block diagram of FIG.
Is provided with a lock-up mechanism B for directly connecting the input / output thereof. The operation of the lock-up mechanism B is controlled by lock-up control means E. The shift operation of the automatic transmission A is controlled by the shift control unit F.

On the other hand, a load detecting means C for detecting the engine load and a deceleration detecting means D for detecting the deceleration of the vehicle are provided, and the signals of the load detecting means C and the deceleration detecting means D are transmitted to the lock-up control means E. The lock-up control means E outputs the lock-up mechanism B in the engagement direction when the engine load is equal to or less than a predetermined value and the deceleration of the vehicle is equal to or less than a predetermined value. Further, the shift control means F receives signals from the load detection means, the deceleration detection means and the lock-up control means, and the engine load is maintained even after the lock-up control means F operates the lock-up mechanism in the fastening direction. When the deceleration of the vehicle is equal to or less than a predetermined value and the deceleration of the vehicle is equal to or less than the predetermined value, a downshift is performed.

(Operation) In the control device for an automatic transmission as described above, when the engine load is equal to or less than a predetermined value and the deceleration of the vehicle is equal to or less than a predetermined value in a running state of the vehicle, that is, when the accelerator is closed. In a load state, for example, when the vehicle is decelerating on a downhill where the vehicle speed does not decrease, the lock-up control means operates the lock-up mechanism in the fastening direction to enhance the direct connection state between the wheel side and the engine and transmit. By increasing the effectiveness of the engine brake by improving efficiency,
Further, when the deceleration does not increase and the vehicle speed does not decrease by the operation of the lock-up mechanism, the shift control means performs a shift-down shift to further enhance the effect of the engine brake, thereby gradually increasing the deceleration state. Thus, the feeling of deceleration is improved and excessive deceleration shock is prevented from occurring.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Second
The figure shows a schematic configuration of the internal mechanism of the automatic transmission.

The automatic transmission 10 includes a torque converter 20 coaxial with an output shaft 1 of an engine serving as an input shaft, and a torque converter 2
And the speed change gear mechanism 30 driven by the output of the second gear.

The torque converter 20 has a pump impeller 22, a turbine runner 23, and a stator 25 disposed in a case 21 with respect to the engine output shaft 1.
22 is fixed to the crankshaft 1 via a turbine case 21, and the turbine runner 23 is fixed to a turbine shaft 27. The stator 25 is supported by the transmission case 11 via a one-way clutch 24, and is provided with a lock-up mechanism 26 (lock-up clutch) that directly connects the input side and the output side. The rotation of the turbine runner 23 is output to the transmission gear mechanism 30 via the turbine shaft 27. A pump shaft 12 is connected to the engine output shaft 1 so as to drive an onl pump 13 at a rear end.

On the other hand, the transmission gear mechanism 30 is a known Ravigneaux-type planetary gear device, and includes a small sun gear 31, a large sun gear 32, a plurality of short pinion gears 33, a long pinion gear 34, a carrier 35, and a ring gear 36. The forward clutch 41, the first one-way clutch 51, the coast clutch 42, the 3-4 clutch 4
3, a reverse clutch 44, a 2-4 brake 45, a second one-way clutch 52, and a low reverse brake 46 are provided. Then, the ring gear 36 is connected to the output gear 14, and the driving force is output from the output gear 14.

The lock-up mechanism 26 is constantly urged by the hydraulic oil pressure circulating in the torque converter 20 in the engagement direction, that is, the direction in which the engine output shaft 1 and the turbine shaft 27 are locked up (directly connected), and supplied from the outside. The release state is maintained by the released hydraulic pressure.

Further, the transmission gear mechanism 30 has a shift stage of a conventionally known type, and a required shift stage can be obtained by appropriately operating the friction engagement element.

The shift control and lock-up control of the automatic transmission 10 are performed by a control system as shown in FIG. With respect to the drive output of the engine 2 being output to the drive wheels via the torque converter 20 and the transmission gear mechanism 30 of the automatic transmission 10, the gear position of the transmission gear mechanism 30 and the operation of the lockup mechanism 26 are controlled by a hydraulic control circuit. 5 (not shown in detail), and is controlled by controlling three solenoid valves 6 to 8 for shifting and one solenoid valve 9 for lock-up of the hydraulic control circuit 5.

Shift and lock-up solenoid valve 6
The control unit 60 that outputs control signals to the control unit 9 includes the lock-up control unit E that performs lock-up control on the automatic transmission 10 and the shift control unit F that performs shift control. Also, the torque converter of the automatic transmission 10
The rotation speed (turbine rotation speed) of the turbine shaft 27 on the output side of 20 is detected by a turbine rotation speed sensor 62 attached thereto, and the throttle opening of the throttle valve 4 provided in the intake passage 3 of the engine 2 is determined by the throttle sensor 61. The output rotation speed sensor detects the rotation speed of the transmission output shaft.
The accelerator opening is detected by an accelerator sensor 64, and a signal from each sensor is input to the control unit 60. The output of the accelerator sensor 64 is handled as information corresponding to the engine load, and the output of the output speed sensor 63 is handled as information corresponding to the vehicle speed (deceleration).

The shift control of the control unit 60 is performed based on the throttle opening and the vehicle speed, for example, a shift-up shift line, a shift, a shift map of a shift map predetermined based on a throttle opening-vehicle speed characteristic shown in FIG. An operation is performed to determine whether or not to perform a shift by checking the down shift line. A shift-up signal or a shift-down signal is output to the shift solenoid valves 6 to 8 of the hydraulic control circuit 5 according to the calculation result, and the shift speed of the automatic transmission 10 is shifted to a higher shift speed by a combination of operations of the valves. Alternatively, control for shifting to the lower gear is performed.

The lock-up control of the control unit 60 should be performed based on the throttle opening signal and the vehicle speed signal by comparing the lock-up operation line and the lock-up release line of the shift map as shown in FIG. An operation is performed to determine whether the lockup should be released. The lock-up operation signal or the lock-up release signal is output to the lock-up solenoid valve 9 of the hydraulic control circuit 5 according to the calculation result.

Further, the lock-up control is performed when the engine load is equal to or less than a predetermined value and the deceleration of the vehicle is equal to or less than a predetermined value according to an engine load based on an accelerator opening and a deceleration based on a change in vehicle speed. The lock-up operation signal for operating the mechanism 26 in the fastening direction is output. Further, after the lock-up operation according to the deceleration, when the deceleration is equal to or less than a predetermined value, the lock-up is released, and then a shift-down signal of the shift control is output.

The control unit 60 as described above can be constituted by, for example, a microcomputer. The operation program of the microcomputer constituting the control unit 60 is executed according to, for example, a flowchart shown in FIG.

The flowchart of FIG. 5 shows only the main routine of the deceleration control. After starting the control, it is determined in step S1 whether or not the engine load is equal to or less than a predetermined value based on whether or not the accelerator opening is fully closed. Also,
In step S2, it is determined whether or not the deceleration is equal to or less than a predetermined value based on whether or not the vehicle speed has decreased.

If the determinations in steps S1 and S2 are YES and the vehicle speed does not change or is increasing in the deceleration state, step S3
Proceed to and the engine speed is a predetermined value (for example, 3,000 rpm)
It is determined whether or not the above high rotation state has continued for a predetermined time (for example, 10 seconds). If the determination in step S3 is YES, it is determined in step S4 whether the vehicle speed is equal to or less than a predetermined value (for example, 50 km / h).

If the determination of any of the above steps S3 and S4 is NO, that is, winding road including a flat road,
If the vehicle speed does not decrease at the time of deceleration during traveling on a steady road except for a state where rapid deceleration is required such as a mountain road with a continuous up curve, the process proceeds to step S5 and the lockup mechanism 26 is engaged. Operate. As a result, the effect of the engine brake is enhanced and a feeling of deceleration is obtained.

After the lock-up state is established as described above, it is determined in step S6 whether or not the accelerator is depressed, and in step S7, it is determined whether or not the vehicle speed has decreased. If the determination in step S6 is NO and the determination in step S7 is YES, the vehicle speed does not decrease even though the deceleration state is maintained and the lockup state is established, so the process proceeds to step S8, and After releasing the up,
In step S9, a downshift is performed to increase the effectiveness of the engine brake.

After performing the downshift as described above, step S10
To determine whether or not the accelerator has been depressed.
If NO and the deceleration state is continued, the step S2
Return to and determine the vehicle speed reduction state.If the vehicle speed still does not decrease, lock-up in step S5 and step
The shift-down of S9 is repeatedly performed.

On the other hand, the determinations in steps S3 and S4 are YES, and the vehicle is at a low vehicle speed (50 km / h or less) and in a high rotation state (3,000 rpm or more)
Is continued (for 10 seconds or more), it is determined that the vehicle is in a winding state including a flat road, or a running state in which rapid deceleration is required such that an upward curve is continuous, and the process proceeds to step S9 to lock the vehicle. The downshift is executed without performing the up operation.

When the determination in step S1 is NO, although not shown, normal shift control and lock-up control based on the shift map in FIG. 4 are performed, and other steps are performed. When the control for increasing the engine brake is terminated based on the determinations in S2, S6, S7, and S10, the normal control is executed similarly.

According to the control of the above-described embodiment, the deceleration is determined from the vehicle speed reduction state, and if the vehicle speed does not decrease even if the accelerator is returned during traveling downhill, first, the lock-up mechanism 26 is engaged. The first stage of operation is performed so that excessive deceleration is obtained while preventing the occurrence of a deceleration shock when suddenly performing a downshift. When the vehicle speed does not decrease in this lockup operation, lockup is performed. After the release, the downshift is performed, and if the vehicle speed does not decrease further, the lockup operation is performed so that the deceleration state is controlled so as to be gradually strengthened, so that the deceleration can be obtained in a stepwise manner.

Further, when rapid deceleration such as a mountain road or a winding road is required from the determination of the rotation state of the engine 2 and the vehicle speed, a downshift can be directly performed to obtain a deceleration state corresponding to the traveling state.

In the above control, the engine load may be detected and determined based on the accelerator opening, or may be determined based on another signal such as a throttle opening. In the control of the lock-up mechanism 26, if the slip control for variably controlling the slip ratio of the lock-up mechanism 26 is adopted, the lock-up operation in step S6 of the flowchart is not necessarily performed in the lock-up state. Not only that, but also control to reduce the slip amount is included. Further, when the vehicle speed does not decrease in the lock-up operation, the shift-down shift is performed after releasing the lock-up in the above-described embodiment, but the shift-down shift is performed without releasing the lock-up. You may.

(Effect of the Invention) According to the present invention as described above, when the engine load is equal to or less than the predetermined value and the deceleration of the vehicle is equal to or less than the predetermined value in the running state of the vehicle, the lock that activates the lock-up mechanism in the engagement direction. Upshift control means and shift control means for performing a downshift when the engine load is equal to or less than a predetermined value and the deceleration of the vehicle is equal to or less than a predetermined value even after the lockup mechanism is operated in the engagement direction. The deceleration state is controlled so as to be gradually strengthened in accordance with the deceleration to improve the feeling of deceleration and prevent an excessive deceleration shock from occurring.

[Brief description of the drawings]

FIG. 1 is a block diagram for clearly showing the configuration of the present invention, FIG. 2 is a schematic configuration diagram of an internal mechanism of an automatic transmission in one embodiment, FIG. 3 is a control system diagram, and FIG. FIG. 5 is a flowchart for explaining the processing of the control unit. A, 10 …… Automatic transmission, 20 …… Torque converter, 30 ……
Transmission gear mechanism, B, 26 lock-up mechanism, 2 engine, 5 hydraulic control circuit, 60 control unit, C
... load detecting means, D ... deceleration detecting means, E ... lock-up control means, F ... shift control means.

Continuation of the front page (56) References JP-A-2-159461 (JP, A) JP-A-58-166165 (JP, A) JP-A-62-246650 (JP, A) JP-A-57-184752 (JP, A) JP-A-57-43050 (JP, A) JP-A-55-103141 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) F16H 45/02 F16H 47/06- 47/08 F16H 59/00-63/48

Claims (1)

(57) [Claims] 1. A vehicle equipped with an automatic transmission having a lock-up mechanism, a load detecting means for detecting an engine load, a deceleration detecting means for detecting a deceleration of the vehicle, the load detecting means, and a deceleration detection. A lock-up control means for operating the lock-up mechanism in a fastening direction when a signal from the means is detected and the engine load is equal to or less than a predetermined value and the deceleration of the vehicle is equal to or less than a predetermined value; And the signals of the deceleration detecting means and the lock-up control means, and after the lock-up control means operates the lock-up mechanism in the fastening direction, the engine load is not more than the predetermined value and the deceleration of the vehicle is not more than the predetermined value. And a shift control means for performing a downshift when a state is detected.