JPH07167288A - Control method of automatic transmission - Google Patents

Abstract

PURPOSE:To appropriately detect abnormality of a lockup control system without utilizing any special sensor. CONSTITUTION:Transmission input rotational speed is calculated by transmission output rotational speed by means of a vehicle speed sensor 72 and a gear ratio of a speed change step of an automatic transmission when a lockup ON signal is outputted from a control unit 80, and abnormality of lockup control systems 70, 83 is detected so as to inhibit lockup control when such a condition that rotational difference between the transmission input rotational speed and the engine rotational speed is larger than a set value, continues for a prescribed period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an automatic transmission, and more particularly to detection of hydraulic pressure in a lockup clutch and abnormality in an electric control system.

[0002]

2. Description of the Related Art Generally, a torque converter of an automatic transmission is provided with a lock-up clutch. For example, lock-up control is performed in conjunction with shift control of 2nd speed or higher to improve power performance, fuel efficiency and the like. There is. Here, the lock-up control system operates the lock-up control valve, for example, by a lock-up signal of the electric control system, and supplies the hydraulic pressure from the oil pump of the hydraulic control system to the torque converter and the clutch apply side to perform the lock-up operation. Alternatively, the lockup is released by supplying the torque converter via the clutch release side. For this reason, if the electric control system malfunctions or breaks, or if the control valve or the like of the hydraulic control system malfunctions, the lockup operation cannot be normally performed or released, resulting in various problems. Therefore, the lockup control system is required to monitor whether or not there is an abnormality in the operation of the lockup clutch.

Conventionally, regarding the detection of abnormality of the lock-up clutch, there is a prior art disclosed in, for example, Japanese Patent Laid-Open No. 2-176265. In this prior art, a transmission input rotation speed sensor is installed, a transmission input rotation speed signal from this sensor is input, and an engine rotation speed signal from the engine rotation speed sensor is input. Then, it is shown that the difference between both rotation speed signals during the output of the lockup actuation signal or the release signal is obtained to judge the failure of the lockup actuation failure or the release failure.

[0004]

By the way, in the above-mentioned prior art, in order to obtain the driven side rotation speed of the lockup clutch, a transmission input rotation speed sensor is specially installed and the clutch drive side rotation speed sensor is installed. Since the failure determination is made based on the engine speed and the input speed of the transmission on the driven side, the number of sensors increases and the cost increases. Generally, the input side of the automatic transmission together with the output side of the torque converter has a multi-shaft structure, and the transmission input shaft is arranged at the innermost side, so it is difficult to install the sensor.
There is a problem that it is necessary to change the configuration of the transmission input side in order to install it forcibly.

In view of the above points, the present invention has an object to detect an abnormality of the lockup control system without using a special sensor.

[0006]

To achieve this object, the present invention provides a lockup control valve of a hydraulic control system by outputting a lockup ON / OFF signal from a control unit of an electric control system to a solenoid. When the lockup ON signal is output in the control system of the automatic transmission that operates by supplying the operating oil pressure to the apply side of the lockup clutch or operating it by releasing it to the release side, the transmission output rotation by the vehicle speed sensor The input speed of the transmission is calculated from the number of gears and the gear ratio of the shift stage of the automatic transmission, and the input speed of the transmission is compared with the engine speed to detect the presence or absence of an abnormality in the lockup control system. To do.

[0007]

In the present invention based on the above control method, when the lockup ON signal is output to the solenoid from the control unit of the electric control system, the working hydraulic pressure is supplied to the apply side of the lockup clutch by the lockup control valve of the hydraulic control system. Operates to engage. At this time, depending on the transmission output speed by the vehicle speed sensor and the gear ratio of the gear stage of the automatic transmission,
The input speed of the transmission on the clutch driven side is accurately calculated. By comparing this transmission input speed with the engine speed on the clutch drive side, it is possible to reliably detect an abnormality when the lockup clutch is not completely engaged due to a failure of the electric control system or hydraulic control system. It

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2, a drive system of a four-wheel drive vehicle with a center differential device will be described as a vehicle with an automatic transmission to which the present invention is applied. First, the transmission case 3 is joined to the rear parts of the torque converter case 1 and the differential case 2, the transfer case 4 is joined to the rear part of the transmission case 3, and the oil pan 5 is attached to the lower part of the transmission case 3. The torque converter case 1 has a torque converter section A, the differential case 2 has a final reduction section B, and the transmission case 3 has an automatic transmission section C.
However, the transfer part (subtransmission) D is arranged in the transfer case 4.

Reference numeral 10 is an engine. A crankshaft 11 of the engine 10 is connected to a torque converter 13 having a lockup clutch 12 of a torque converter section A, and an input shaft 14 from the torque converter 13 is an automatic transmission section C. Input to the automatic transmission 30. The transmission output shaft 15 from the automatic transmission 30 outputs coaxially with the input shaft 14,
The transmission output shaft 15 is connected to the center differential device 50 of the transfer section D.

Inside the transmission case 3, the front drive shaft 1 with respect to the input and output shafts 14 and 15
6 are arranged in parallel, the rear end of the front drive shaft 16 is connected to the center differential device 50 via a pair of reduction gears 17 and 18, and the front end of the front drive shaft 16 is connected to the front differential device 19 of the final reduction section B. It is configured to be transmitted to the front wheels via. On the other hand, at the rear of the center differential device 50, a transfer clutch 51 is provided as a hydraulic multiple disc clutch for limiting the differential.
The rear drive shaft 20 output from the transfer clutch 51 is configured to be transmitted to the rear wheels via a propeller shaft 21, a rear differential device 22, and the like.

The automatic transmission 30 is constructed so that four forward gears and one reverse gear can be obtained by two sets of front planetary gears 31 and rear planetary gears 32. That is, the input shaft 14 is connected to the sun gear 32a of the rear planetary gear 32, and the ring gear 31b of the front planetary gear 31 and the carrier 32c of the rear planetary gear 32 are connected to the transmission output shaft 15. And the carrier 3 of the front planetary gear 31
A first one-way clutch 34 and a forward clutch 35 are provided in series between the coupling element 33 that is integral with 1c and the ring gear 32b, and the first one-way clutch 34 and the forward clutch 35 are provided between the coupling element 33 and the case side that is the fixing member. 2 one-way clutch 3
6. A low reverse brake 37 is provided in parallel.
An overrunning clutch 38 is provided as a bypass between the connecting element 33 and the ring gear 32b.

The connecting element 3 which is integral with the sun gear 31a
9, a band brake 40 is provided, and a high clutch 43 is provided between the coupling element 41 integral with the input shaft 14 and the coupling element 42 integral with the carrier 31c. Further, a reverse clutch 44 is provided between the connecting elements 39 and 41.

Due to the structure of the automatic transmission 30, the forward clutch 35 is engaged in the first speed of the D range or the third range and the second range, and in the case of acceleration, the one-way clutches 34 and 36 work together with the coupling element 33 and the ring gear. 32
By locking b, the sun gear 32
Power is transmitted to the transmission output shaft 15 via a and the carrier 32c. During coasting, the first one-way clutch 34 becomes free, and even if the free running of the first one-way clutch 34 is restricted by engaging the overrunning clutch 38, the second one-way clutch 36 becomes free. The engine brake does not work. In the 1st speed of 1 range, the ring gear 32b is always locked by the engagement of the low reverse clutch 37 via the overrunning clutch 38, so that the engine brake is applied.

In the 2nd speed of the D range or 3 range and 2 range, the forward clutch 35 and the band brake 4 are used.
0 engages, and the band gear 40 locks the sun gear 31a. Therefore, the carrier 31c and the ring gear 32b connect the connecting element 33 and the forward clutch 3 to each other.
5, rotating via the first one-way clutch 34,
The power that is increased by the amount of rotation of the ring gear 32b is output as compared with the speed. At this time, during deceleration, the engagement of the overrunning clutch 38 keeps the connecting element 33 and the ring gear 32b in the connected state, so that the reverse driving force is transmitted to the engine side and the engine brake acts.

At the third speed in the D range or the third range, the forward clutch 35 and the high clutch 43 are engaged, and the high clutch 43 causes the input shaft 14 to move to the connecting element 41 ,.
32, the carrier 31c, the connecting element 33, the forward clutch 35, and the first one-way clutch 34 to connect to the ring gear 32b. Therefore, the rear planetary gear 32 is integrated, and the input shaft 14 and the transmission output shaft 15 are directly connected. At this time, when decelerating, the overrunning clutch 38 is coupled to restrict the idling of the first one-way clutch 34, so that the engine brake acts similarly to the second speed.

In the fourth speed of the D range, the sun gear 31a is locked by the engagement of the band brake 40 in addition to the above. For this reason, the front planetary gear 31 is engaged with the high clutch 43.
By the power input to the carrier 31c by the ring gear 31
The speed b is increased, and this is transmitted to the transmission output shaft 15. In this case, the engine brake is always applied because the first and second one-way clutches 34 and 36 are not used.

In the R range, the power of the input shaft 14 is input to the sun gear 31a by coupling the reverse clutch 44. Further, since the carrier 31c is locked together with the connecting element 33 by the engagement of the low reverse clutch 37, the front planetary gear 31 reversely rotates to the ring gear 31b to output power with a large gear ratio, and this reverse power is transmitted to the transmission output shaft 15. And then reverse speed. In this way, the automatic transmission 30 can obtain a shift speed of four forward gears and one reverse gear.

The transfer section D will be described. First, the center differential device 50 is of a compound planetary gear type, and transmits transmission power by unequal torque distribution to front and rear wheels at a reference torque distribution ratio according to gear specifications. In addition, a differential action is taken to absorb the difference in rotational speed between the front and rear wheels during turning. The transfer clutch 51 is provided between the two output elements of the center differential device 50. Then, the clutch pressure is controlled according to the slip state of the front and rear wheels to perform a differential limiting action, and the front and rear wheel torque distribution is variably controlled according to the differential limiting torque.

An oil pump 45 is installed in front of the automatic transmission 30 and is constantly driven by a drive shaft 46 on the pump impeller side of the torque converter 13. The oil pan 5 accommodates a control valve body 47 having various valves and solenoids for gear shift control, lockup control, and transfer control.

Referring to FIG. 1, a control system for gear shift control and lockup control will be described. As the hydraulic control system 60,
The oil pump 45, which communicates with the oil pan 5 and generates the working oil pressure Po, is connected to the duty solenoid 6 by the oil passage 61a.
6, the line pressure signal having a predetermined duty ratio is operated to operate the duty solenoid 66, and the pressure control valve 62 regulates the pressure in a pilot manner to generate a predetermined line pressure PL. The oil passage 61b of the line pressure PL is connected to the shift solenoid 6 via the manual valve 63.
7 is connected to the shift valve 64, and the shift solenoid 67 is operated by the shift signal to operate the shift valve 6 in the pilot type.
4 by switching operation, each shift clutch 35, 37,
.. Supply and drain oil to and selectively engage.

The oil passage 61a for the operating oil pressure Po communicates with the lockup control valve 65 having the duty solenoid 68. And lock-up ON of a predetermined duty ratio
When the signal is input, the lockup control valve 65 supplies the operating oil pressure Po to the torque converter 13 and the apply chamber 12a of the lockup clutch 12 through the oil passage 61c,
In addition, the release chamber 12b of the lockup clutch 12 is drained by the oil passage 61d, and the lockup clutch 12 is drained.
Is engaged by the hydraulic pressure difference. Lock-up OFF
On the contrary, when the signal is inputted, the operating oil pressure Po is switched to be supplied to the torque converter 13 via the oil passage 61b through the release chamber 12b of the lockup clutch 12, and the lockup clutch 12 is released.

Further, as an electric control system 70, a throttle sensor 71 for detecting a throttle opening, an automatic transmission 30.
Speed sensor 7 that detects the vehicle speed by the rotation speed on the output side of
2. An inhibitor switch 73 for detecting each range position is provided, and these signals are input to the control unit 80.
The control unit 80 has a mode selector 81 for inputting the vehicle speed and the throttle opening, and selects a normal mode shift pattern that emphasizes fuel consumption or a power mode shift pattern that emphasizes acceleration performance, depending on the vehicle speed and accelerator depression speed. The throttle opening, vehicle speed, range position and mode signals are input to the shift control unit 82 and the lockup control unit 83. The shift control unit 82 refers to the shift pattern of each mode, sets a shift stage of, for example, the first speed to the fourth speed according to the driving and running state, and outputs a signal of this shift stage to the solenoid output control unit 84.
To enter. Then, it is converted into a shift signal corresponding to the shift stage and output to the shift solenoid 67.

The lockup control unit 83 sets the lockup ON / OFF characteristic according to the shift pattern, throttle opening, vehicle speed, range position, gear position, etc. of each mode.
That is, the lockup is turned on under a predetermined operating condition of the second or higher speed, and the lockup is turned off at other times or when shifting.
Then, the solenoid output control unit 84 converts the duty ratio according to the lockup ON / OFF and outputs the duty ratio to the duty solenoid 68. The throttle opening and the range position are input to the line pressure control unit 85, and the line pressure PL according to the throttle opening is set for each range. Then, the solenoid output control unit 84 is configured to convert the duty ratio according to the line pressure PL and output the duty ratio to the duty solenoid 66.

Further, the abnormality detection of the lockup control system will be described. First, when the lockup clutch 12 operates normally, the crankshaft 11 of the engine 10 is directly connected to the input shaft 14. Therefore, the engine speed Ne on the clutch drive side when the lockup ON signal is output
Is equal to the transmission input speed Ni on the clutch driven side. Further, the vehicle speed sensor 72 detects the transmission output rotation speed No and calculates the transmission output rotation speed No by multiplying the transmission output rotation speed No by a constant gear ratio of the final reduction unit. Therefore, by using the transmission output rotation speed No obtained by the vehicle speed sensor 72 and the gear ratio i of each gear, the transmission input rotation speed Ni can be calculated by Ni = i · No. Therefore, when the lockup ON signal is output, the engine speed Ne and the transmission output speed No,
An abnormality of the lock-up clutch 12 can be detected by comparing the transmission input speed Ni with the gear ratio i, and an abnormality of the shift control can be detected by using the gear ratio i of each shift stage.

Therefore, there is provided a lockup abnormality detecting section 86 to which the engine speed Ne by the ignition pulse 74, the vehicle speed, the shift speed of the shift control section 82, and the lockup signal of the lockup control section 83 are inputted. Then, when the lockup ON signal is output as described above, the engine speed Ne is compared with the transmission output speed No and the transmission input speed Ni based on the gear ratio i, and the rotation difference between them is equal to or greater than the set value. When the state of (3) continues for a predetermined time, it is determined that the lockup clutch 12 is abnormal. When the lockup clutch 12 is abnormal, an alarm 87 is displayed by an abnormal signal, and the solenoid output control unit 84 switches to the lockup OFF signal to prohibit the lockup control.

Next, the operation of this embodiment will be described. First, when the engine 10 is operated in the P or N range, engine power is input to the pump impeller side of the torque converter 13 via the crankshaft 11, and further transmitted to the oil pump 45 by the drive shaft 46 to be driven. Therefore, the oil in the oil pan 5 generates an operating oil pressure Po, and this operating oil pressure Po is introduced into the pressure adjusting valve 62 and the lockup control valve 65.

When the vehicle is stopped, the gear position is set to the first speed, the lockup control section 83 of the control unit 80 sets lockup OFF, and this signal is output by the duty solenoid 68.
Output to. Then, the lockup control valve 65 causes the operating oil pressure Po to change the operating pressure Po to the release chamber 12 of the lockup clutch 12.
is supplied to the torque converter 13 via b, the lockup clutch 12 is released, and the engine power is transmitted via the torque converter 13 and the input shaft 14 to the automatic transmission 3
Enter 0. At this time, the line pressure signal from the line pressure control unit 85 is output to the duty solenoid 66, so that the pressure adjusting valve 62 adjusts the line pressure PL to a predetermined line pressure PL.

When shifting to the D range and depressing the accelerator to start normally, the line pressure PL is guided to the shift valve 64 by the manual valve 63. The shift control unit 82 sets the first speed based on the shift pattern in the normal mode, and the solenoid output control unit 84 outputs this shift signal to the shift solenoid 67. Therefore, the shift valve 64 further introduces the line pressure PL into the forward clutch 35 and engages it, whereby the first speed is changed. Therefore, due to the converter action of the torque converter 13 and the large gear ratio i of the automatic transmission 20, large shifting power is output to the output shaft.

This speed change power is torque-distributed by the center differential device 50, and one power having a predetermined distribution ratio is transmitted to the front wheels via the reduction drive gear 17, the reduction driven gear 18, the front drive shaft 16, and the front differential device 19. . The other power is transmitted to the rear wheels via the rear drive shaft 20, the propeller shaft 21, and the rear differential device 22, and the vehicle starts with four-wheel drive.

When the vehicle speed increases after starting, the second speed is set, and this shift signal is output and the shift valve 64 further acts on the band brake 40 by refueling, whereby the second speed is changed. Similarly, when the throttle opening is the same, the gears are automatically changed to the third speed and the fourth speed according to the increase of the vehicle speed, and it becomes possible to travel at a high speed in the state where the engine speed Ne is low.

Further, when the vehicle speed is relatively high such as the second speed or higher, the torque converter 13 shifts from the converter region to the coupling region. Therefore, under predetermined traveling conditions, except during shifting, the lockup control unit 83 sets lockup ON, and this ON signal is output to the duty solenoid 68. Therefore, the lockup control valve 65
As a result, the operating oil pressure Po is supplied to the apply chamber 12a of the lockup clutch 12 via the torque converter 13, and is switched to drain the release chamber 12b. Therefore, the lockup clutch 12 operates so as to be engaged due to the hydraulic pressure difference between the apply chamber 12a and the release chamber 12b, whereby the crankshaft 11 is directly connected to the input shaft 14, and the engine power is directly transmitted to the automatic transmission 30. Enter well.

Next, the abnormality detection when the lockup control is performed as described above will be described with reference to the flowchart of FIG. This flowchart is executed every predetermined time,
First, the gear position is referred to in step S1, and the gear ratio i of the gear position is calculated in step S2. Then, in step S3, the presence or absence of lockup is checked, and lockup OF is performed.
If F, return.

When the lockup ON signal is output, the routine proceeds to step S4, where the transmission input rotation speed Ni is calculated from the transmission output rotation speed No by the vehicle speed sensor 72 and the gear ratio i. Then, in step S5, the rotation difference between the engine rotation speed Ne on the clutch drive side and the transmission input rotation speed Ni on the clutch driven side is compared with a set value a. If the rotation difference is less than or equal to the set value a, lockup is performed in step S6. Clutch 1
2 is judged to be normally engaged, and then it comes out.

On the other hand, if the rotation difference is equal to or greater than the set value a, it is checked in step S7 whether or not it has continued for a predetermined time, and if it is within the predetermined time, the process proceeds to step S6 and is judged to be normal.
After continuing for a predetermined time, the process proceeds to step S8 to determine an abnormality. Even if the lockup ON signal is output in this manner, the lockup clutch 12 is not completely engaged due to a failure of the electric control system 70 or the hydraulic control system 60, and the engine speed Ne on the clutch drive side and the gear shift on the clutch driven side. When a rotation difference between the machine input rotation speed Ni and the machine input rotation speed Ni continues for a predetermined time, an abnormality is reliably detected. When this abnormality occurs, the process proceeds to step S9 to switch to the lockup OFF signal. Therefore, the lockup clutch 12 is forcibly released, and the lockup control is prohibited.

Since the lockup ON is controlled intermittently, even if an abnormality is detected in the previous lockup ON, the rotation difference is equal to or less than the set value a in step S5 in the case of the current lockup ON. Or if it is within the predetermined time in step S7, the process proceeds to step S6 to judge normality and exit as it is. Therefore, the lockup clutch 12 is held in a normally engaged state.

The embodiments of the present invention have been described above, but the present invention is not limited to these.

[0037]

As described above, according to the present invention,
When the lockup control system abnormality is detected, the transmission input rotation speed on the driven side of the lockup clutch is calculated from the transmission output rotation speed of the vehicle speed sensor and the gear ratio of the shift stage of the automatic transmission. The need for a sensor is eliminated, which is advantageous in terms of cost, and it is not necessary to change the structure of the automatic transmission. Since the gear ratio of the shift stage of the automatic transmission is used, abnormality in shift control can also be detected.

[Brief description of drawings]

FIG. 1 is a block diagram of an electric control system and a hydraulic control system showing an embodiment suitable for a control method for an automatic transmission according to the present invention.

FIG. 2 is a skeleton diagram showing an example of a drive system of an automatic transmission to which the present invention is applied.

FIG. 3 is a flowchart of an abnormality detection control of a lockup control system.

[Description of Reference Signs] 12 Lockup clutch 13 Torque converter 30 Automatic transmission 60 Hydraulic control system 65 Lockup control valve 68 Duty solenoid 70 Electric control system 72 Vehicle speed sensor 80 Control unit 83 Lockup control unit 86 Lockup abnormality detection unit

Claims (2)

[Claims] 1. A lockup ON / OFF signal from a control unit of an electric control system is output to a solenoid so that a hydraulic pressure control system lockup control valve supplies an operating hydraulic pressure to an apply side of a lockup clutch. Then
Or, in the control system of the automatic transmission that supplies to the release side and releases it, when the lock-up ON signal is output, the transmission input rotation speed is determined by the transmission output speed of the vehicle speed sensor and the gear ratio of the gear stage of the automatic transmission. A method for controlling an automatic transmission, characterized in that the number of revolutions is calculated, and the input speed of the transmission is compared with the engine speed to detect the presence or absence of an abnormality in the lockup control system. 2. When the lockup ON signal is output,
When the difference between the transmission input rotation speed and the engine rotation speed is equal to or more than the set value for a predetermined time, the lockup control system is judged to be abnormal and the lockup clutch is forcibly released. The method of controlling an automatic transmission according to claim 1.