JP3039169B2 - Control device for automatic transmission for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention determines a stable running state of a vehicle, such as a slipping state of a drive wheel, by detecting the acceleration of the output shaft rotation speed of the automatic transmission. The present invention relates to a control device for a vehicle automatic transmission that controls a shift.

[0002]

2. Description of the Related Art For example, when a vehicle is to be started on a road surface having a low coefficient of friction, such as a frozen road surface, a slip on the tire occurs because the driving force of the engine easily exceeds the road grip force of the tire. Easy to occur. Once a slip occurs on the tire, the road surface friction coefficient generally further decreases, so that the vehicle is hardly accelerated and cannot start.

On the other hand, in this state, the output shaft of the automatic transmission directly connected to the tires continues to rotate, so that the output of the output shaft rotation speed sensor generally mounted here as a vehicle speed sensor increases. The timing calculation circuit erroneously diagnoses that the speed of the vehicle has increased, generates a shift command, and executes the shift. As a result, the rotation of the tire changes abruptly, and the vehicle body tends to skid or the like.

[0004] As a technique for solving such a problem,
In Japanese Patent Publication No. 64-7259, a slip state of a drive wheel is determined by detecting an acceleration of an output shaft speed of an automatic transmission, and a slip occurs when the acceleration is larger than a predetermined value. A technology that prohibits shifting is proposed.

[0005] Since this technique uses the output of an existing output shaft speed sensor (vehicle speed sensor), it can be easily realized without increasing the cost, and is considered to be a highly practical technique.

[0006]

However, the method of detecting the slip state based on the acceleration of the output shaft rotation speed is not always highly reliable in practice. Unnecessary shift prohibition is executed due to misdiagnosis that there is a shift, and as a result, a feeling of gear shift failure occurs, or conversely, despite slipping, it is erroneously diagnosed that there is no slip and the slip is further increased. However, there has been a problem that the durability of the differential gear of the differential may be reduced.

That is, when a predetermined value (threshold) for avoiding a shift is set to a small value, a slip may be erroneously detected, for example, when the vehicle suddenly starts on a high μ road.
Conversely, if this predetermined value is set to a large value, there is a problem that it is difficult to detect a slip at a gentle start.

[0008] Further, when canceling the shift prohibition control, there is a problem that the reduction of the acceleration and the elimination of the slip may not always be related. That is, the slip may continue even if the acceleration decreases, and in this case, it may be erroneously determined that the slip does not occur.

The present invention has been made in view of such a conventional problem, and as in the conventional case, the cost is hardly increased by using the existing sensor. It is an object of the present invention to provide a control device for a vehicular automatic transmission that can recognize a slip state and execute appropriate shift prohibition control.

[0010]

[0011]

Means for Solving the Problems] The present first invention, FIG. 1
As shown in ( A ), an automatic transmission for a vehicle that determines the stable running state of a vehicle by detecting the acceleration of the output shaft rotation speed of the automatic transmission and controls the shift of the automatic transmission based on the determination. Means for prohibiting shifting when the acceleration of the output shaft speed is greater than a first predetermined value; means for determining an engine load; and a means for determining that the engine load is smaller than a predetermined value and the acceleration is at a second predetermined value. when less than the value, I and means for releasing the prohibition of the shifting
Thus, the above- mentioned problem is also solved by setting the second predetermined value to be smaller than the first predetermined value .

As shown in FIG. 1 ( B ), the second invention is characterized in that, in the first invention, a means for calculating an elapsed time after the shift is inhibited, and an elapsed time after the shift is inhibited. Means for canceling the prohibition of the shift when the predetermined time is exceeded, regardless of the values of the engine load and the acceleration, are also provided to solve the above-mentioned problem.

[0013]

[0014]

[0015]

[0016]

SUMMARY OF present first and second invention is obtained by focusing on the release of the prohibition control of speed change.

According to the first aspect of the present invention, when the acceleration of the output shaft rotation speed is larger than a predetermined value, control for inhibiting gear shifting is started, and the engine load is smaller than the predetermined value and the acceleration of the output shaft rotation speed is smaller than the predetermined value. This is canceled when it becomes.

The first predetermined value relating to the acceleration at the time of entering the shift prohibition control and the second predetermined value relating to the acceleration at the time of canceling are set to the second predetermined value at the time of canceling when other conditions such as the engine load are the same . Although the predetermined value is smaller, for example, the engine load is higher for the predetermined value for each acceleration.
Set the first and second predetermined values to a larger value as the set value increases.
As a matter of course, the first and second predetermined values may be changed depending on the engine load or the like.

According to the first aspect of the present invention, once the shift inhibition control is entered, the acceleration is not released only when the acceleration is reduced, and the acceleration is compared with the acceleration when the shift is inhibited.
The acceleration becomes smaller than the predetermined value, and at the same time, is released on condition that the engine load becomes smaller than a predetermined value. According to the first aspect , it is possible to more reliably prevent the shift from being executed while the shift should be prohibited due to the erroneous determination.

On the other hand, the second invention is based on the first invention, and further obtains an elapsed time after the shift is prohibited, and when the elapsed time exceeds a predetermined time, the values of the engine load and the acceleration are calculated. Regardless, the shift prohibition is canceled.

This takes into account the following conditions.

That is, according to the first aspect , once the shift inhibition control is started, the shift inhibition is not released unless the engine load becomes smaller than a predetermined value. However, for example, when the vehicle moves from a road surface having a low friction coefficient to a road surface having a high friction coefficient while the shift prohibition control is being executed, the driver steps on the accelerator despite the fact that the slip has been eliminated. It is likely to continue. However, in this case, since the slip has already been eliminated, there is no reason to continue to execute the shift inhibition control.

Further, the shift prohibition is not released even when the vehicle continues to run while slightly slipping on a road surface having a low friction coefficient. However, even if the vehicle slips slightly, the fact that the engine load is equal to or higher than the predetermined value for a long time (the accelerator pedal is kept depressed) is a result of the driver's determination that the vehicle is safe. In such a case, it is not appropriate to continue to prohibit gear shifting.

According to the second aspect of the present invention, the shift prohibition is canceled when a certain period of time has passed after the shift was prohibited, regardless of the values of the engine load and the acceleration. There is no state, and a feeling similar to that of a normal shift can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is an overall schematic diagram of an automatic transmission combined with an electronic fuel injection engine for a vehicle to which the present invention is applied.

This automatic transmission has a torque converter 2
0, overdrive mechanism 40, three forward steps, one reverse step
And a stepped underdrive mechanism 60.

The torque converter section 20 includes a pump 2
1, a turbine 22, a stator 23, and a lock-up clutch 24. The output of the crankshaft 10 of the engine 1 is
Transmit to 0.

The overdrive mechanism 40 includes a sun gear 43, a ring gear 44, a planetary pinion 42,
And a set of planetary gear units consisting of
The rotational state of the planetary gear unit is controlled by a clutch C0, a brake B0, and a one-way clutch F0.

The underdrive mechanism 60 includes two sets of planetary gear units including a common sun gear 61, ring gears 62 and 63, planetary pinions 64 and 65, and carriers 66 and 67. The rotation state and the connection state with the overdrive mechanism 40 are controlled by clutches C1, C2, brakes B1 to B3, and one-way clutches F1, F2.

A computer 84 for controlling the automatic transmission includes a throttle sensor 80 for detecting a throttle opening for reflecting the load of the engine 1 and a vehicle speed sensor (a rotational speed sensor for the output shaft 70) 82 for detecting a vehicle speed No. A sensor 99 for detecting the rotational speed of the clutch C0, a shift position switch 5 for outputting a shift position signal, a brake switch 6 for outputting a signal when a foot brake is depressed, a Ne sensor 7 for detecting the engine rotational speed Ne,
Idle contact state (O when the accelerator pedal is depressed)
Signals for various controls, such as an idle switch 8 for outputting FF) and a water temperature switch 9 for detecting a cooling water temperature T of the engine, are input.

The computer 84 sets the solenoid valves S1, S2, S3, and S3 in the hydraulic control circuit 106 in accordance with a preset throttle opening-vehicle speed shift point map using input signals from the respective sensors, switches, and the like as parameters.
S4 and the like are driven and controlled, and a shift control is performed by performing a combination of engagement of each clutch and brake as shown in FIG.

When a predetermined condition is satisfied in accordance with the following control flow, the throttle opening-
The shift based on the shift point map of the vehicle speed is prohibited.

FIG. 4 shows a control flow relating to the shift inhibition control.

First, in step 201, the flag F
1 and F2 are cleared and initialized. In this embodiment, in order to prevent malfunction and erroneous determination, the shift inhibition control is executed only when the control execution condition is satisfied twice or more. That is, the backup flag F1 is set when the first condition is established, but at this stage, the shift inhibition control is not yet executed. Then, when the second condition is satisfied, that is, when the control execution condition in the state of F1 = 1 is satisfied, the execution flag F2 becomes 1, and the shift inhibition control is executed for the first time.

When canceling the shift prohibition control, the backup flag F1 is set for the same purpose.

In step 202, the execution flag F2
Is 1 or not. If F2 = 0, that is, if the control is not being executed, the routine proceeds to step 203, where the current throttle opening .theta. Is compared with a threshold .theta.xa which is one of the control start conditions. If θ ≦ θxa, it is not necessary to execute the shift prohibition control, so the routine proceeds to step 211, where the backup flag F1 is reset to 0.

On the other hand, if θ> θxa, step 204
Subsequently, it is determined whether or not the rate of change dNo of the output shaft rotation speed (vehicle speed) per unit time is greater than a threshold value mapped in advance for each shift speed. That is, step 204
Then, it is determined whether or not the automatic transmission is at the first speed,
If it is the first speed, the routine proceeds to step 205, where the actual change rate dNo of the vehicle speed (output shaft rotation speed) No per unit time
And a magnitude dNo1 which is a map value (threshold) of the rate of change dNo of the vehicle speed No per unit time set depending on the throttle opening as shown in FIG.

If dNo> dNo1 in step 205, that is, if it is considered that the tire slip is large, the prohibition control needs to be executed, and the process proceeds to step 206. In step 206, the value of the backup flag F1 is determined. Here, when the value of F1 is 0, it means that the prohibition control condition has been satisfied for the first time this time.
Proceeding to step 208, F1 is set to one. On the other hand, if it is already determined that the backup flag F1 is 1, the routine proceeds to step 207, where the execution flag F2 is set to 1.
Is determined, and when F2 is not 1,
Since this means that the second shift prohibition control execution condition has been satisfied for the first time, the routine proceeds to step 212, where the execution flag F2 is set to 1 and the count of the release timer t is started.

On the other hand, when it is determined in step 207 that the execution flag F2 is 1, it is determined that the execution flag F2 has already passed step 212, and the process returns.

On the other hand, in step 205, dNo> d
If No 1 is not established, there is no need to execute control, so the routine proceeds to step 211, where the backup flag F
1 is reset to 0.

If it is determined in step 204 that the current speed is not the first speed, the magnitude of the slip is similarly determined in steps 209 and 210 based on the threshold dNo2 (see FIG. 5) in the second speed. Is determined.

In this embodiment, the first speed and the second speed
Since it is intended to execute the control related to the shift prohibition only at the speed stage, the process proceeds to step 211 when neither the first speed stage nor the second speed stage and the flag F1 is reset to 0. It has become.

If it is determined in step 202 that the execution flag F2 is 1, it means that the shift prohibition control has already been started, so the process proceeds to step 213 to determine whether the shift prohibition control is released. enter.

First, the release timer t (step 212)
Is determined to have reached a predetermined value Tx. If it is determined that the elapsed time since the execution flag F2 is set to 1, that is, the elapsed time since the shift prohibition control has reached the predetermined value Tx, step 214 is executed to forcibly cancel the prohibition control. To the flag F1
, F2 are both reset to zero.

On the other hand, if it is determined in step 213 that the elapsed time t has not yet reached the predetermined value Tx, the process proceeds to step 215 in order to determine whether another release condition is satisfied.

In step 215, it is determined whether or not the current throttle opening θ is smaller than a threshold θxb, which is one of the release conditions. In step 216, the current change rate dNo of the output shaft rotational speed No is released. D, which is the threshold of the condition
It is determined whether it is smaller than No3. Specifically, this threshold value dNo3 is determined for each throttle opening and each shift speed.
The value is set lower than dNo 1 and dNo 2.

If any one of the steps 215 and 216 is not satisfied, the process proceeds to step 217 to set the backup flag F1 to 1 in order to continue the prohibition control, and then returns. This is because F1 = 0 when the return condition is satisfied at the time of the previous flow.

If the conditions of steps 215 and 216 are both satisfied, it is determined that the release condition has been satisfied, and the routine proceeds to step 218, where the value of the backup flag F1 is determined. If the cancellation condition is satisfied for the first time this time, F1 = 1
Therefore, the routine proceeds to step 219, where F1 is first reset. At this stage, the prohibition control is not yet released. However, if the release condition is satisfied again in the next flow, it is determined in this step 218 that F1 is 0.
2 is set to 0.

In the computer 84, the throttle opening-
Before (or after) the step of determining the shift speed based on the shift point map of the vehicle speed, the value of the execution flag F2 is determined. When the value of the execution flag F2 is 0, the value is determined on the basis of the shift point map of throttle opening-vehicle speed. The gear shift control is executed so as to achieve the gear position set as described below. When the execution flag F2 is 1,
Even if the current running state is such that the shift should be executed according to the shift point map, the execution of the shift is prohibited and the current gear position is maintained.

According to this embodiment, the backup flag F1 is provided in addition to the execution flag F2, and it is confirmed that a plurality of executions of the execution condition of the shift inhibition and the establishment of the release condition are confirmed a plurality of times. The control is executed and released. Therefore, even when the condition is satisfied only instantaneously due to pulsation, or when the execution condition or the release condition is temporarily satisfied due to the mixing of pulse noise, the control is not confused by this. It can be executed and released.

Further, according to this embodiment, in determining whether the execution condition is satisfied, the threshold value of the acceleration of the output shaft rotation speed (change rate of the output shaft rotation speed) depends on the engine load and the type of shift. The actual slip state can be grasped very accurately.

In order to release the shift prohibition, it is required that the engine load be equal to or less than a predetermined value and that all the accelerations of the output shaft speed be equal to or less than a predetermined value.
It is possible to reliably prevent the shift inhibition control from being released even though the slip is still continuing.

Further, if a predetermined period of time has elapsed since the shift prohibition control was executed under such conditions, for example, the vehicle may be running for a long time on a road surface having an extremely low friction coefficient, or may be executed once. It is considered that the release condition may not be satisfied due to circumstances such as the vehicle is traveling on a road with a high friction coefficient (while depressing the accelerator pedal) while traveling on a road with a low friction coefficient such that the conditions are satisfied. In such a case, it is not appropriate to prohibit the shift as it is, so the shift prohibition control is forcibly released.

Therefore, with these arrangements, it is possible to prohibit shifting only when it is necessary to prohibit shifting more than ever.

[0056]

As described above, according to the present invention,
Despite the cost-saving method of detecting the acceleration of the output shaft speed, it is possible to more accurately grasp the state where gear shifting should be prohibited, and execute more appropriate gearshift inhibition control. The excellent effect that it becomes possible to do it is acquired.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a block diagram showing a schematic configuration around a vehicle automatic transmission to which the present invention is applied;

FIG. 3 is a diagram showing an engagement state of each friction engagement device in the automatic transmission.

FIG. 4 is a flowchart showing a control flow executed in the automatic transmission.

FIG. 5 is a diagram showing a set amount of a threshold value when shifting to shift inhibition control;

[Explanation of symbols]

 80 ... Throttle sensor 82 ... Vehicle speed sensor (output shaft speed sensor) 84 ... Computer F1 ... Backup flag F2 ... Execution flag (for shift prohibition control)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-54371 (JP, A) JP-A-59-151655 (JP, A) JP-A-3-121367 (JP, A) JP-A-4- 272568 (JP, A) JP-A-62-2049 (JP, A) JP-A-2-42255 (JP, A) JP-A-63-6260 (JP, A) JP-A-2-2033073 (JP, A) Japanese Utility Model Application Hei 9-96068 (JP, U) Japanese Utility Model Application Hei 4-50755 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16 -61/24 F16H 63/40-63/48

Claims (2)

(57) [Claims] An automatic transmission control device for a vehicle, which determines a stable running state of a vehicle by detecting acceleration of an output shaft rotation speed of the automatic transmission and controls a shift of the automatic transmission based on the determination. Means for prohibiting gear shifting when the acceleration of the output shaft rotation speed is greater than a first predetermined value; means for obtaining an engine load; and when the engine load is smaller than a predetermined value and the acceleration is smaller than a second predetermined value. wherein it comprises a means for canceling the prohibition of the shifting, the control device for a vehicular automatic transmission, characterized in that the smaller the second predetermined value than the first predetermined value. 2. A method according to claim 1, further comprising : means for calculating an elapsed time after the shift is prohibited; and when the elapsed time after the shift is prohibited exceeds a predetermined time, the means for determining an engine load and an acceleration value. Means for canceling the shift prohibition, and a control device for an automatic transmission for a vehicle, comprising: