JPH09280350A - Control device for automatic transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a slip without increasing a hydraulic pressure by a method wherein a slip during non-gear shifting of a selected hydraulic engaging element is detected and when a slip is detected by a slip detecting means, a drive force is reduced to shift down an automatic gear shifter through reduction of a drive force. SOLUTION: An output circuit 21 of an electronic control unit U controls operation of clutches C1 , C2 , C3 , and C4 R of an automatic transmission T. A slip detecting means detects it based on a throttle opening, the number of revolutions of a main shaft, the number of revolutions of a counter shaft, and a shift position whether the present engaged clutches C1 , C2 , C3 , and C4 R are slipped or not. A gear shift control means shifts down the automatic transmission T so as to prevent the occurrence of the slips of the clutches C1 , C2 , C3 and C4 R. This constitution reliably prevents the occurrence of a slip without increasing a hydraulic pressure, and prevents worsening of a gear shift feeling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission for a vehicle, which shift-controls an automatic transmission by selectively engaging a plurality of hydraulic engagement elements based on a driving state of the vehicle.

[0002]

2. Description of the Related Art The hydraulic pressure for engaging a hydraulic clutch and a hydraulic brake provided in an automatic transmission for a vehicle is set to a minimum necessary pressure from the viewpoint of reducing shift shock. However, there is a case where the hydraulic pressure is not sufficient in a specific operating state of the vehicle, which causes a problem that the hydraulic clutch and the hydraulic brake slip and durability deteriorates.

Therefore, the control device for an automatic transmission for a vehicle disclosed in Japanese Patent Laid-Open No. 4-300457 discloses a hydraulic pressure supplied to the hydraulic clutch or brake when slippage of the hydraulic clutch or hydraulic brake is detected. To suppress slip.

[0004]

However, when the hydraulic pressure is increased when the hydraulic engagement element is slipped as in the prior art, not only the hydraulic circuit becomes complicated, but also the shift feeling is deteriorated. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably prevent slippage of a hydraulic engagement element without increasing hydraulic pressure.

[0006]

In order to achieve the above-mentioned object, the invention described in claim 1 is configured to automatically engage a plurality of hydraulic engagement elements based on an operating state of a vehicle. In a control device for an automatic transmission for a vehicle that shift-controls a transmission, a slip detection unit that detects a slip of a selected hydraulic engagement element during non-shift, and a drive force when the slip detection unit detects a slip. And a shift control unit that shifts down the automatic transmission by lowering the shift.

Further, in addition to the structure of claim 1, the invention described in claim 2 further comprises a predicting means for predicting a time until a shift down is executed by the shift control means when a slip is detected. The amount of decrease in the driving force is changed based on the predicted time.

The invention described in claim 3 is characterized in that, in addition to the configuration of claim 2, the longer the time predicted by the prediction means, the larger the decrease amount of the driving force is set.

Further, in the invention described in claim 4, in addition to the structure of claim 1, after the shift down is executed by the shift control means, the shift stage after the shift down is held until a predetermined time elapses. It is characterized by

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 5 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of an automatic transmission and its control device,
FIG. 2 is a block diagram showing a circuit configuration of the electronic control unit,
3 is a flow chart for explaining the action, FIG. 4 is a graph for explaining the action, and FIG. 5 is a time chart for explaining the action.

As shown in FIG. 1, an automatic transmission T for a vehicle is shown.
Includes a main shaft MS connected to the crankshaft 1 of the engine E via a torque converter 2 having a lockup clutch L, and a countershaft CS connected to the main shaft MS via a plurality of gear trains. .

The main shaft MS supports a main first speed gear 3, a main second speed gear 4, a main third speed gear 5, a main fourth speed gear 6 and a main reverse gear 7, and the counter shaft CS has a main first speed gear 3. Counter first speed gear 8 that meshes with main second speed gear 9, counter second speed gear 9 that meshes with main second speed gear 4, counter third speed gear 10 that meshes with main third speed gear 5, and counter fourth speed gear 1 that meshes with main fourth speed gear 6
1 and main reverse gear 7 reverse idle gear 1
The counter reverse gear 12 connected via 3 is supported.

When the main first speed gear 3 rotatably supported on the main shaft MS is connected to the main shaft MS by the first speed clutch C ₁ , the first speed gear is established. Since the first speed clutch C ₁ is maintained in the engaged state even when the second speed to the fourth speed is established, the counter first speed gear 8 is supported via the one-way clutch C _OW . When the main second speed gear 4 rotatably supported on the main shaft MS is connected to the main shaft MS by the second speed clutch C ₂ , the second speed gear stage is established. When the counter third speed gear 10 rotatably supported on the counter shaft CS is connected to the counter shaft CS by the third speed clutch C ₃ , the third speed gear is established.

With the counter fourth speed gear 11 rotatably supported on the counter shaft CS being coupled to the counter shaft CS by the selector gear SG, the main shaft M is
The main 4th speed gear 6 supported by S for relative rotation is 4th speed-
When the reverse clutch C _4R is connected to the main shaft MS, the fourth speed gear is established. With the counter reverse gear 12 rotatably supported on the counter shaft CS being coupled to the counter shaft CS by the selector gear SG, the counter reverse gear 7 rotatably supported on the main shaft MS is connected to the fourth speed-reverse clutch C _4R. When connected to the main shaft MS at, the reverse speed is established.

The rotation of the counter shaft CS is transmitted to the differential D via the final drive gear 14 and the final driven gear 15, and from there to the drive wheels W, W via the left and right axles 16, 16.

The electronic control unit U includes a CPU 17 and a ROM
18, a RAM 19, an input circuit 20, and an output circuit 21.

The throttle opening TH detected by the throttle opening sensor S ₁ provided on the engine E, the main shaft rotation speed N _MS detected by the main shaft rotation speed sensor S ₂ provided on the main shaft _MS, and the counter shaft CS
Counter shaft rotation speed N _CS detected by the counter shaft rotation speed sensor S ₃ provided in the
The vehicle speed V detected by the vehicle speed sensor S ₄ provided in the vehicle and the shift speed P detected by the shift position sensor S ₅ are input to the input circuit 20 of the electronic control unit U.

On the other hand, the output circuit 21 of the electronic control unit U
Is the first speed clutch C of the automatic transmission T₁2-speed clutch
Chi C_Two3rd speed clutch C_Three4-speed-reverse clutch
Chi C _4R, Selector gear SG and lockup clutch L
Of the hydraulic control circuit O for controlling the operation of the
Tosolenoid SL₁, SL_Two, Lockup clutch
Renoid SL_Three, SL_FourAnd shift clutch hydraulic Soleno
Id SL_FiveConnected to.

As shown in FIG. 2, the electronic control unit U comprises a slip detection means M1, a shift control means M2, and a prediction means M3.

The slip detecting means M1 is based on the throttle opening TH, the main shaft rotational speed N _MS , the counter shaft rotational speed N _CS and the shift position P, and the currently engaged clutches C ₁ , C ₂ , C ₃ , C _4R is detected whether it is slipping or not. Shift control means M2, when the clutch _{C 1, C 2, C 3} , C 4R slip is detected, shifts down the automatic transmission T in order to eliminate the slip. The predicting means M3 predicts the time until the downshift is executed, and controls the shift control means M2 so that the downshift is executed at a predetermined timing.

Next, the operation of the embodiment of the present invention having the above configuration will be described.

When the position of the select lever of the automatic transmission T is set to the "D4" range or the "D3" range which is the automatic shift range, and the second speed, the third speed or the fourth speed is established. During traveling, in step S1 of the flowchart of FIG. 3, the throttle opening TH detected by the throttle opening sensor S ₁ is about 0.2 / 8, which corresponds to a fully closed opening T.
It is between H _MIN and the control range determination opening TH _{CPC of} about 1.3 / 8 to 1.5 / 8, the automatic transmission T is not in gear shifting in step S2, and is currently engaged in step S3. If no slip has occurred in the engaged clutch, the process proceeds to step S4. In step S4, the slip control flag F _DOWN indicating that the clutch slip prevention control is being _executed is not set to "1" in the initial state, and therefore the control is ended as it is.

The slip detection of the clutch in step S3 is performed by the slip detection means M1, and the engaged clutch of the four clutches C ₁ , C ₂ , C ₃ and C _4R is the target of slip detection. Becomes In the embodiment, the main shaft rotation speed N _MS detected by the main shaft rotation speed sensor S ₂ and the counter shaft rotation speed sensor S
The presence or absence of slip is determined by calculating the rotational speed difference ΔN between the input side and the output side of the engaged clutch from the counter shaft rotational speed N _CS detected in ₃ . At this time, when there is no slip, the rotation speed difference ΔN between the input side and the output side does not occur, and when there is slip, the rotation speed on the input side becomes higher than the rotation speed on the output side and the rotation speed difference ΔN occurs.

In addition to the above, the presence or absence of slip can be determined based on the clutch slip ratio ECL shown in the following equation.

ECL = (N _CS / N _MS ) × R R; gear ratio clutch slip ratio EC when clutch is not slipping
The value of L becomes 1, and when the clutch slips and the main shaft rotation speed N _MS increases, the value of the clutch slip ratio ECL becomes smaller than 1. Therefore, the reference slip ratio E1
(E1 <1) is compared with the clutch slip ratio ECL,
When the clutch slip rate ECL becomes smaller than the reference slip rate E1, it is determined that the clutch has shifted to the slip state.

When the clutch shifts to the slip state, the slip control flag F _DOWN is not set to "1" in the initial state in step S5, and thus the step shifts to step S6. In step S6, the engine output reduction control flag F indicating that the shift control means M2 is operated to execute the downshift by reducing the engine output to perform the engine output reduction control by the ignition retard.
_{The RTD} is set to "1" to reduce the engine output, and the slip control flag F _DOWN indicating that the clutch slip prevention control is in progress is set to "1".

The automatic transmission T is downshifted when the vehicle speed decreases due to the reduction in the engine output and the vehicle crosses the downshift line of the shift map stored in the ROM 18 of the electronic control unit U in advance. Therefore, for example, when slippage occurs in the 4th-reverse clutch C _4R during traveling at the 4th speed shift stage, the clutch is downshifted to the 3rd speed shift stage, and slippage occurs at the 3rd speed clutch C ₄ while traveling at the 3rd speed shift stage. When it occurs, the gear is downshifted to the second gear, and when the second speed clutch C ₂ slips while traveling at the second gear, the gear is downshifted to the first gear.

The engine output reduction amount can be set to a fixed value according to the engine output at that time, but in the embodiment, the prediction means M3 starts the reduction of the engine output until the shift down is executed. Time to vehicle speed V
Is controlled based on the rate of decrease of the engine output. If the prediction time is long, the engine output reduction amount is increased, and if the prediction time is short, the engine output reduction amount is decreased. In this way, by determining the engine output reduction amount based on the predicted time from the start of engine output reduction to the execution of downshift, it is possible to always generate downshift at a constant timing.
If it is predicted that the downshift will be executed promptly, the reduction of the engine output may be stopped at that time.

When the downshift is started as described above, it is determined in step S2 of the next loop that gear shifting is in progress, and the engine output reduction control flag F _RTD is reset to "0" in step S7. Then, the reduction of the engine output during the shift of the automatic transmission T is stopped. Eventually, if the shift is completed and it is determined in step S2 that the shift is not in progress, the process proceeds to step S3, and if the slip is still not resolved at that time, the process proceeds to step S5.
In step S5, since the slip control flag F _DOWN has already been set to "1" (see step S6), the process proceeds to step S8, the engine output reduction control flag F _RTD is set to "1" again, and the shift is performed again. The reduction of the engine output is restarted to perform the down, and the shift hold flag F _HOLD described later is reset to “0”.

If the slip is eliminated in step S3 by reducing the engine output and downshifting, step S3
Move to 4. In step S4, the slip control flag F
Step S because _DOWN is still set to "1"
9, the engine output reduction control flag F _RTD
Has already been reset to "0" (see step S7), the process proceeds to step S10 and the shift hold flag F _HOLD is set to "1".

The shift hold flag F _HOLD prohibits shift-up from the currently established shift stage P until a predetermined time counted by a timer elapses. In this way, even if the operating state of the vehicle exceeds the shift-up line of the shift map, the shift-up is prohibited, so that the shift hunting in which the shift-down and the shift-up are alternately performed between the adjacent gears P is prevented.

When the driver depresses the accelerator pedal and the throttle opening TH goes out of the range of step S1, the process proceeds to step S11 and the slip control flag F
_DOWN , engine output reduction control flag F _RTD and shift hold flag F _HOLD are all reset to "0" to return to the initial state, and the control is terminated.

By the way, the substantial capacity (transmittable torque) of the clutch is set to be larger for low-speed clutches engaged at high engine output such as when starting or accelerating, and the same throttle opening TH and the same vehicle speed V. In this case, since the engine speed used for lower speeds is higher, the real capacity is higher for lower speeds in the same situation. Therefore, when the clutch slips, if the gear is shifted down to the lower speed gear P, the clutch slip can be prevented or reduced. Further, due to the difference in engine speed, the actual capacity is smaller as the vehicle speed V is lower at the same gear P, so that slip is likely to occur near the shift line between the gear P adjacent to the low speed side. According to the control of 1, the shift down can be immediately executed to prevent the clutch from slipping.

Further, even if there is no difference in the actual capacities of the clutch before the shift and the clutch after the shift, the relationship between the throttle opening TH and the vehicle speed V changes due to the shift down, and the slip occurrence region of the clutch. You can escape from.

Explaining this concretely with reference to FIG. 4, there is a possibility that slip will occur at the fourth speed in the shift map in which the horizontal axis represents the vehicle speed V and the vertical axis represents the throttle opening TH. When the clutch slips in the 4th speed slip zone, the engine output is reduced to reduce the vehicle speed, and the 4th speed → 3rd speed shift down line is crossed to shift down from the 4th speed shift stage to the 3rd speed shift stage. It is possible to prevent the clutch from slipping.

Further, even if the fourth gear is downshifted to the third gear, if the slip still occurs in the third slip zone, the engine output is further reduced to reduce the vehicle speed to 3 It is possible to prevent the clutch from slipping by crossing the speed-> 2nd gear shift down line and downshifting from the 3rd gear to the 2nd gear.

Next, an example of the operation of the flowchart of FIG. 3 will be described based on the time chart of FIG. The broken line in FIG. 5 shows the characteristics when the clutch slip prevention control according to the present invention is not performed.

For example, when the gear P is in the third gear, the throttle opening TH is the fully closed equivalent opening TH _MIN, and the control range determination opening TH _CPC is 0.5 / 8 during traveling, The vehicle speed V begins to decrease from time t ₁ when approaching the slope (a
Point), it is assumed that the currently engaged third speed clutch C ₃ starts to slip at time t ₂ . _{3 at} time t 3
When the rotational speed difference ΔN between the input side and the output side due to the slip of the speed clutch C ₃ exceeds the threshold value (point c), the slip control flag F _DOWN is set to “1” and the slip prevention control is started. At the same time (point d), the engine output reduction control flag F _RTD is set to "1", and engine output reduction is started (point e).

As a result, the vehicle speed V further decreases and crosses the downshift line of the shift map, so that the downshift to the second speed shift stage is started at time t ₄ (point f), and the engine output reduction control flag F _RTD. Is reset to “0” and the engine output reduction is completed (point g), and at the same time, the high speed side third speed clutch C ₃ is disengaged and the low speed side second speed clutch C ₂ is engaged ( h point and i point).
Then, at time t ₅ , when the throttle opening TH increases beyond the control range determination opening TH _CPC (point j), the slip control flag F _DOWN is reset to “0”, the slip prevention control ends, and the throttle opening As the TH increases, the shift-up line of the shift map is crossed so that the shift-up to the third speed is performed (point k).

The embodiments of the present invention have been described in detail above, but the present invention can be modified in various ways without departing from the scope of the invention.

For example, although the engine output is reduced by the ignition retard in the embodiment, the fuel cut or the throttle valve may be closed instead of the ignition retard.

[0043]

As described above, according to the invention described in claim 1, when the hydraulic engagement element slips during non-shifting, the driving force is reduced to downshift the automatic transmission. It is possible to reliably prevent slippage of the hydraulic engagement element without increasing the hydraulic pressure and avoid deterioration of the shift feeling.

According to the second aspect of the present invention,
The time until the shift down is executed when the slip is detected is predicted, and the amount of decrease in the driving force is changed based on the predicted time, so that the shift down can be always generated at a constant timing. .

According to the third aspect of the present invention,
Since the amount of decrease in the driving force is set to be larger as the predicted time until the shift-down is executed is longer, the delay of the shift-down can be avoided and the slip can be promptly eliminated.

According to the invention described in claim 4,
Since the shift speed after the shift down is held until a predetermined time elapses after the shift down is executed, shift hunting in which the shift down and the shift up are repeated can be prevented.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an automatic transmission and its control device.

FIG. 2 is a block diagram showing a circuit configuration of an electronic control unit.

FIG. 3 is a flowchart explaining the operation.

FIG. 4 is a graph illustrating the operation

FIG. 5 is a time chart explaining the operation

[Explanation of symbols]

C ₁ 1st speed clutch C ₂ 2nd speed clutch C ₃ 3rd speed clutch C _4R 4th speed-reverse clutch M 1 slip detection means M 2 shift control means M 3 prediction means T automatic transmission

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Hagiwara 1-4-1, Chuo, Wako, Saitama Stock Company Honda R & D Co., Ltd.

Claims (4)

[Claims] 1. A plurality of hydraulic engagement elements (C ₁ , C ₂ ,
C _3, the C _4R) control device for a vehicular automatic transmission shift control an automatic transmission (T) by selectively engaging on the basis of the driving state of the vehicle, selected hydraulic engaging element ( automatic C _1, and C _2, C _3, slip detecting means (M1 for detecting a slip in the non-shifting time of C _4R)), slip detecting means (M1) is by lowering the driving force upon detecting a slip A control device for an automatic transmission for a vehicle, comprising: a shift control means (M2) for shifting down a transmission (T). 2. A predicting means (M3) for predicting a time until shift-down is executed by the shift control means (M2) when a slip is detected is provided, and the driving force is based on the predicted time. 2. The control device for an automatic transmission for a vehicle according to claim 1, wherein the amount of decrease of V is changed. 3. The control device for an automatic transmission for a vehicle according to claim 2, wherein the longer the time predicted by the predicting means (M3), the larger the decrease amount of the driving force is set. 4. The automatic gear shift for a vehicle according to claim 1, wherein after the shift down is executed by the shift control means (M2), the shift speed after the shift down is held until a predetermined time elapses. Machine control device.