JPH05126246A - Speed change control device for automatic transmission - Google Patents

Abstract

PURPOSE:To ensure running without deteriorating durability of a friction engaging device at fail time thereof. CONSTITUTION:A speed change control device is for an automatic transmission A set to a plurality of speed change shifts in accordance with combination of engaging/disengaging a plurality of friction engaging devices. A speed change shift judging means 1 for judging a speed change shift, which must be set based on a running condition of car speed, engine load, etc., is provided. The device provides a fail judging means 2 for judging whether setting is right or not of the speed change shift judged by the speed change shift judging means 1 and a speed change command means 3 for commanding a speed change to the other settable speed change shift in the case of judging unsettable the speed change shift which must be set by this fail judging means 2. Further, the device is provided with an input torque reduction command means 4 for outputting a command of reducing input torque in the case of commanding a speed change to the other speed change shift by this speed change command means 3.

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 in an automatic transmission for a vehicle.

[0002]

2. Description of the Related Art As is well known, in the conventional general stepped automatic transmission, a frictional engagement device such as a clutch, a brake, or a one-way clutch is appropriately engaged and disengaged, and the engagement and disengagement thereof are performed. It is configured to set a predetermined shift speed according to the combination. The friction engagement devices are configured to have a transmission torque capacity that is slightly larger than the torque that is supposed to act, thereby preventing unnecessary enlargement of the device and increasing the hydraulic pressure excessively. It prevents fuel consumption from deteriorating.

However, when one of the friction engagement devices cannot hold the required transmission torque capacity due to deterioration of the friction material or the decrease of hydraulic pressure, in other words, when a failure occurs, the friction engagement device is used. It becomes impossible to set the gear stage to be engaged. Generally, the gear stage to be set is determined based on the running condition such as vehicle speed and engine load, so that the determined gear stage engages the friction engagement device that cannot hold the required transfer torque capacity. If it is a gear, the gear cannot be set, and the vehicle cannot run. Therefore, the present applicant has already proposed a device capable of avoiding such inconvenience in Japanese Patent Application No. 2-40521.

The control device of Japanese Patent Application No. 2-40521 determines a state in which the frictional engagement device cannot be engaged, that is, a fail state, and selects a shift speed that can be set based on the determined fail state. It is a device configured to ensure traveling.

[0005]

As described above, each shift speed in the automatic transmission is judged based on the running condition such as the vehicle speed and the throttle opening, and the friction engagement device for setting the shift speed. Has a transmission torque capacity suitable for the traveling state. However, since the above-mentioned device cannot set the shift speed determined from the running state, it is unavoidable to set another shift speed.
The set gear is not necessarily suitable for the running state, and the friction engagement device engaged for setting the gear is loaded with a torque larger than the expected torque. There is a risk. Therefore, in the above-mentioned conventional device, when another gear is set in order to ensure the running of one of the friction engagement devices at the time of failure, excessive torque acts on the friction engagement device to cause slippage, As a result, the durability of the friction engagement device may decrease.

The present invention has been made in view of the above circumstances, and provides a gear shift control device capable of ensuring running of the friction engagement device when the friction engagement device fails and preventing deterioration of durability of the friction engagement device. The purpose is to do.

[0007]

The present invention is characterized in that it has the structure shown in FIG. 1 in order to achieve the above object. That is, FIG. 1 is a block diagram showing the principle of the present invention, and the device of the present invention is an automatic transmission in which a plurality of gear stages are set in accordance with a combination of engagement and release of a plurality of friction engagement devices. A shift control device of A,
A shift speed determination means 1 for determining a shift speed to be set based on a running state such as a vehicle speed and an engine load, and a fail determination for determining whether or not the shift speed to be set determined by the shift speed determination means 1 can be set. The means 2, the shift command means 3 for commanding a shift to another shift speed that can be set when the fail determination means 2 determines that the shift speed to be set cannot be set, and the shift command means 3 It is characterized by further comprising input torque reduction command means 4 for outputting a command to reduce the input torque when a shift command to the other shift stage is commanded.

[0008]

The automatic transmission A which is the subject of the present invention can be set to a plurality of gear stages by appropriately engaging and disengaging a plurality of friction engagement devices.
The shift stage to be set is determined by the shift stage determination means 1 based on the traveling state such as vehicle speed and engine load. On the other hand, if the fail determination means 2 determines whether or not the shift speed to be set can be set, that is, whether or not the shift speed to be set can be set, and it is determined that the shift speed to be set cannot be set, The shift command unit 3 outputs a shift command to set another shift stage different from the shift stage determined by the shift determining unit 1. Along with this, the input torque reduction command means 4 outputs a command to reduce the input torque to the automatic transmission A. This input torque is in particular the input torque to the gear transmission, which input torque may therefore be reduced by reducing the output torque of the engine, or by reducing the torque amplification effect in the torque converter. You may.

[0009]

2 is a block diagram showing an embodiment of the present invention, in which an automatic transmission A shown here is a torque converter 10 with a lockup clutch and a forward drive unit 4. It has a gear train 11 capable of setting one shift speed and one reverse speed.
This gear train 11 includes a first and a second planetary gear mechanism 12,
13 and a plurality of clutches and brakes, the carrier 14 of the first planetary gear mechanism 12 and the ring gear 15 of the second planetary gear mechanism 13 are connected to each other, and the ring gear 16 and the first gear of the first planetary gear mechanism 12 are connected to each other. 2 Planetary gear mechanism 13
Is connected to the carrier 17.

An input shaft 18 connected to the turbine runner 10a of the torque converter 10 is arranged along the central axes of the planetary gear mechanisms 12 and 13.
A first clutch C1 is provided between the input shaft 18 and the sun gear 19 of the first planetary gear mechanism 12, and a second clutch C2 is provided between the input shaft 18 and the carrier 17 of the second planetary gear mechanism 13. ing. Further, a third clutch C3 is provided between the input shaft 18 and the sun gear 20 of the second planetary gear mechanism 13. On the other hand, a fourth clutch C4 and a first one-way clutch F1 which are arranged in series with each other are provided between the carrier 17 and the sun gear 20 in the second planetary gear mechanism 13. In this first one-way clutch F1, the rotation direction of the clutch drum of the fourth clutch C4, that is, the rotation direction of the sun gear 20 in the state where the fourth clutch C4 is engaged, is the forward rotation direction (input It engages when the rotation direction is the same as the rotation direction of the shaft 18. This 4th
Between the clutch drum of the clutch C4 and the casing 21, there is provided a second one-way clutch F2 which is engaged when the clutch drum tries to reversely rotate (rotate in the direction opposite to the input shaft 18). ..

As a braking means, a first brake B1 which is a band brake is provided on the outer circumference of the clutch drum of the fourth clutch C4, and the first brake B1 is connected to the first brake B1.
The second brake B that stops the rotation of the ring gear 16 of the planetary gear mechanism 12 and the carrier 17 of the second planetary gear mechanism 13.
Two are provided. Therefore, the first brake B1 is
The rotation of the carrier 17 and the rotation of the sun gear 20 in the second planetary gear mechanism 13 are selectively stopped via the fourth clutch C4 or the first one-way clutch F1.

The above-mentioned clutches C1 to C4 and brakes B1 and B2 are adapted to be engaged and released by the hydraulic pressure controlled by the hydraulic control device 22, and this hydraulic control device 22 is controlled by an electronic control unit (ECU). ) 23. The electronic control unit 23 includes a central processing unit (CPU) and storage devices (RAM, RO).
M) is mainly composed of an input / output interface and outputs a command signal to the hydraulic control device 22 according to a predetermined program to control gear shifting and engagement / disengagement of a lockup clutch (not shown). If a failure of the friction engagement device is detected based on the further input signal, and if a failure of the friction engagement device is detected, the friction engagement device is disengaged from the gear stage or the friction engagement device. A gear that reduces the torque is selected, and a command signal for reducing the input torque is output. The electronic control unit 23 is supplied with output signals from the turbine rotation speed sensor 24 and the output shaft rotation speed sensor 25 in addition to other signals such as vehicle speed V, throttle opening θ, and engine water temperature.

In the gear train shown in FIG. 2, the forward first speed to the fourth speed and the reverse speed are established by engaging the clutches C1 to C4 and the brakes B1 and B2 as shown in the operation table of FIG. Can be set. Note that FIG.
In the operation table of, the circle indicates the engaged state, the blank indicates the released state, and the double circle indicates the engaged state during engine braking.

Next, the operation of the above-described device will be described by taking as an example the case where a failure occurs in which the transmission torque capacity of the first clutch C1 is insufficient. FIG. 4 is a flow chart showing a routine for determining the failure of the first clutch C1 and the shift control accompanied therewith. First, in step 1, it is determined whether or not the traveling range set is the D (drive) range, If the judgment result is “No”, the control process returns, and if “Yes”, Step 2
Then, it is determined whether the current gear is the first speed or the second speed. That is, it is determined whether or not the shift speed is such that the input torque is transmitted only by the first clutch C1. If the result of the determination is "no", the control process returns, and if "yes", the process proceeds to step 3. Then, it is determined whether or not the power is on.

The determination process of step 3 is a process of determining whether or not the torque applied to the first clutch C1 is large. If the determination result is "no", the control process returns, and If "yes", the routine proceeds to step 4, where it is judged whether or not the gear ratio actually achieved is largely deviated from the gear ratio of the second speed. Specifically, the gear ratio that is actually achieved is calculated as the ratio (Nt / No) of the turbine speed Nt and the output speed No, and the calculated value and the gear ratio ρ2 of the second speed are calculated.
The absolute value of the difference (Nt / No-ρ2) from the predetermined value γ
Determine if greater than 2. If the result of the determination is “No”, it means that the actually achieved gear ratio does not deviate significantly from the gear ratio of the second speed, so that the first clutch C1 has the desired transmission torque capacity. Control process and therefore the control process returns. If the determination result is "yes", it is determined that the gear ratio actually achieved by the abnormality of the first clutch C1 is largely deviated from the gear ratio of the second speed, and thus the step 5 is performed. Next, it is determined whether or not the actually achieved gear ratio deviates greatly from the first gear ratio.

Specifically, similarly to the determination in step 4, the speed ratio actually achieved as the ratio (Nt / No) between the turbine speed Nt and the output speed No is obtained and calculated. It is determined whether or not the absolute value of the difference (Nt / No-.rho.1) between this value and the gear ratio .rho.1 of the first speed is larger than a predetermined value .gamma.1. If the result of the determination is "No", it means that the gear ratio actually achieved does not deviate significantly from the gear ratio of the first speed, and therefore the first clutch C1 has the desired transmission torque capacity. Will be
Therefore, the control process returns. If the determination result is "yes", it is determined that the gear ratio actually achieved by the abnormality of the first clutch C1 is largely deviated from the gear ratio of the first speed. In that case, Proceed to step 6 and change to first speed or second speed and change to third
Outputs a shift signal that sets the speed. In step 7, a command signal for reducing the input torque is output.

Therefore, if it is determined that the first clutch C1 is abnormal, the first speed or the second speed, which transmits the input torque only by the first clutch C1, is changed to
The third speed for engaging the first clutch C1 and the second clutch C2 is set, and at the same time, the input torque is reduced.
As a result, the torque applied to these clutches C1 and C2 becomes small, so that even if the transmission torque capacity of the first clutch C1 becomes small, the third speed can be set without excessive slippage, and the clutch can be set. The traveling can be secured without lowering the durability of the.

As means for reducing the input torque, specifically, means for delaying the ignition timing of the engine,
A means for reducing the fuel injection amount, a means for reducing the torque amplification effect in the torque converter, or the like can be adopted.

In the above embodiment, the first clutch C1
However, the present invention is not limited to the above-mentioned embodiment, and the failure of the second clutch C2 is not limited to the above-mentioned embodiment. It is also possible to detect in the same manner, set the second speed instead of the fourth speed or the third speed based on the detection result, and simultaneously reduce the input torque. Further, it is also possible to detect a failure of a friction engagement device other than the input clutch, set another gear in place of the gear engaged with the friction engagement device, and simultaneously reduce the input torque.

Further, the shift control device of the present invention is not limited to the above embodiment, and is also applied to a shift control device for an automatic transmission having a gear train other than the gear train shown in FIG. can do.

[0021]

As is apparent from the above description, according to the gear shift control device of the present invention, when the friction engagement device has a failure, the gear position determined from the running state is changed to
By setting another shift speed at which the torque applied to the friction engagement device becomes zero or small and simultaneously reducing the input torque, it is possible to ensure traveling and reduce the torque applied to the friction engagement device. It is possible to prevent the excessive slippage and prevent deterioration of the durability of the friction engagement device.

[Brief description of drawings]

FIG. 1 is a block diagram showing in principle a shift control device of the present invention.

FIG. 2 is a block diagram schematically showing an embodiment of the present invention.

FIG. 3 is an operation table of the automatic transmission shown in FIG.

FIG. 4 is a flowchart showing a control routine when a failure occurs in the first clutch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shift determining means 2 Fail determining means 3 Shift commanding means 4 Input torque reducing means A Automatic transmission

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Ota 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (1)

[Claims] 1. A shift control device for an automatic transmission having a plurality of shift stages set in accordance with a combination of engagement and release of a plurality of friction engagement devices, based on a running state such as a vehicle speed or an engine load. A shift speed determining means for determining a shift speed to be set, a fail determining means for determining whether or not the shift speed to be set determined by the shift speed determining means is set, and the shift determining means for determining the shift speed to be set. A gear shift command means for instructing a shift to another gear that can be set when it is determined that the gear cannot be set, and an input torque is reduced when the gear shift command means commands a gear shift to the other gear. A shift control device for an automatic transmission, comprising: input torque reduction command means for outputting a command to cause a shift to occur.