JP2501805B2 - Transmission control device for automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission including at least two friction engagement elements that are alternately engaged and disengaged between a low speed stage and a high speed stage.

2. Description of the Related Art In an automatic transmission for a vehicle, a gear ratio is switched by supplying hydraulic pressure such as hydraulic oil to friction engagement elements such as clutches and brakes to appropriately select rotary elements such as a rotating drum and gears. The speed change is automatically performed according to the driving condition of the vehicle. For example, as disclosed in Japanese Patent Laid-Open No. 57-47056, the frictional engagement is performed to protect the devices and equipment and to maintain a comfortable riding comfort. The hydraulic pressure supplied to the coupling element is appropriately controlled.

As a conventional automatic transmission, for example, the Automotive Engineering Handbook published by the Society of Automotive Engineers, Vol. 5 (issued June 20, 1983)
There is a forward two-speed automatic transmission as shown on pages 1-19 of the above. This automatic transmission is provided with one set of clutches and two sets of band brakes as friction engagement elements. One clutch is used as a high speed stage friction engagement element and one band brake is used as a low speed stage friction engagement element. I'm running. Incidentally, the other band brake is adapted to be used as a friction engagement element for reverse travel.

Therefore, when shifting from the low speed stage to the high speed stage during forward movement, the shift shock is reduced by gradually releasing the band brake on the low speed stage side while engaging the clutch on the high speed stage side. ing.

Problems to be Solved by the Invention However, in such a conventional automatic transmission,
Since the one-way clutch is not installed in the power transmission path of the gear train, if the upshift from the low speed stage to the high speed stage due to throttle off etc. while running with engine braking, the input speed is forcibly changed as the clutch is engaged. However, there was a problem in that it caused a significantly large gear shift shock and rattling noise of the drive system.

Therefore, the present invention, when shifting up to a high speed stage with engine braking, first releases the friction engagement element for the low speed stage to make the gear train idle, and then predicts the time when the gear ratio reaches the set value for the high speed stage. Then, by controlling so that the high-speed stage engagement elements that reach the set point of the predicted gear ratio are completely engaged, the automatic shift control that prevents or significantly reduces the upshift shock during engine braking is performed. An object of the present invention is to provide a shift control device for a transmission.

Means for Solving the Problems In order to achieve such an object, the shift control device of the automatic transmission according to the present invention is hydraulically operated as shown in FIG.
A low-speed stage frictional engagement element a that is fastened at a low-speed stage and released at a high-speed stage, and a high-speed stage frictional engagement element b that is released at a low-speed stage and fastened at a high-speed stage are provided. In an automatic transmission in which the hydraulic fluid pressures a and b are controlled by low-speed and high-speed hydraulic actuators c and d driven by pressure signals, the input and output rotational speeds of the gear train e are changed. The input and output rotational speed detecting means f and g for detecting the input and output
A gear ratio detecting means h for detecting an apparent gear ratio from a ratio of input and output rotational speeds obtained by the output rotational speed detecting means f and g;
A change rate detecting means i for detecting a change rate of the gear ratio based on the detection value of the gear ratio detecting means h, and a change rate detecting means i for shifting up from a low speed stage to a high speed stage to an engine braking state. The gear ratio predicting means j for predicting the gear ratio after the operation start delay time of the high speed friction engagement element b on the basis of the changed gear ratio change rate, and the low speed in response to the shift command from the low speed to the high speed. the fast time to output a release signal of the low-speed stage friction engaging element a in-gear hydraulic actuator c, and the predicted gear ratio R _e of the gear ratio predicting means j reaches below the gear ratio of the high gear Control means k for outputting the engagement signal of the high-speed stage frictional engagement element b to the stage hydraulic actuator d.
And are provided.

In the irregular control device for an automatic transmission according to the present invention having the above-described structure, when shifting from the low speed stage to the high speed stage to the engine braking state, the control means k first receives the shift command and the low speed stage hydraulic pressure is controlled. A drive signal is output to the actuator c to release the low speed stage frictional engagement element a. Then, the gear train e enters the inertia phase state, and an apparent gear ratio change occurs as the input rotation speed decreases. This change in gear ratio is detected by the gear ratio detecting means h, and the gear ratio predicting means i further predicts the gear ratio of the high speed gear frictional engagement element b after the operation start delay time. This operation start delay time is the time from when the engagement signal of the high-speed stage frictional engagement element b is output to the high-speed stage hydraulic actuator d until the actual engagement of the high-speed stage frictional engagement element b is started. By setting,
At the time when the gear ratio predicting means j predicts the gear ratio of the high speed stage, the control means k causes the hydraulic actuator for the high speed stage d.
A fastening signal of the high-speed-stage frictional engagement element b is output to. Then, since the apparent gear ratio of the gear train e is set at or near the gear ratio of the high speed gear at the time when the high speed gear frictional engagement element b is started to be engaged, a substantial shift up operation is performed. The torque is smoothly introduced, and the shift shock is prevented or greatly reduced.

Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

That is, FIG. 2 shows a shift control device 10 for an automatic transmission showing an embodiment of the present invention, and the gear train 12 of the automatic transmission in which this shift control device 10 is used is, for example, the one shown in FIG. To be The gear train 12 is a planetary gear set and includes two sun gears S ₁ and S ₂ and two pinion gears P ₁ and
Ravigneaux gear train 14 consisting of P ₂ and one ring gear I
Is used. The input shaft 16 of the gear train 12 and one of the sun gears S ₁ are a clutch C as a friction engagement element for the high speed stage.
And the one sun gear S ₁ can be fixed via a band brake B ₁ as a low-speed stage frictional engagement element. Further, the other sun gear S ₂ is mounted on the input shaft 16, the ring gear I can be solidified through the reverse band brake B ₂ , and the one pinion gear P ₁ is one sun gear S ₁ and the ring gear. The other pinion gear P ₂ is meshed with the pinion gear P ₁ and the other sun gear S ₂ , and these two pinion gears P ₁ and P ₂ are connected to the output shaft 1 via one pinion gear rear C.
It is attached to 8.

In the gear train 12, as shown in the following table, the friction engagement elements C, B ₁ and B ₂ are engaged and released at each shift speed.

In the table, a circle mark indicates a fastening state, and a cross mark indicates a releasing state. The table also shows the reduction ratios at each gear, but P ₁ = a ₁ / d and P ₂ = a ₂ / d, where a ₁ is one sun gear S ₁
The number of teeth of a, a ₂ is the number of teeth of the other sun gear S ₂ , and d is the ring gear I
Is the number of teeth.

In the figure, 20 is an engine, 22 is a torque converter, and the power of the engine 20 is input to the input shaft 16 of the gear train 12 via the torque converter 22.

By the way, the one set of clutch C and the two sets of band brakes B ₁ and B ₂ are engaged by being supplied with a reduced pressure and released by removing a hydraulic pressure. The hydraulic pressure is controlled by the first, second and third solenoid valves 30, 32, 34 as high speed, low speed and reverse hydraulic actuators. Further, the input shaft 16 and the output shaft of the gear train 12
18 is the input shaft speed sensor 36 and the output shaft speed sensor
38 is provided, and detection signals from these sensors 36, 38 are output to the controller 40 of the shift control device 10 shown in FIG.

The controller 40 includes the input / output shaft rotation speed sensor.
The input shaft rotational speed detecting means 42 and the output shaft rotational speed detecting means 44 for calculating the input shaft rotational speed (N _T ) and the output shaft rotational speed (N ₀ ) respectively by inputting the detection signals from 34 and 38 are built-in. ing. The respective rotation speeds calculated by the input and output shaft rotation speed detection means 42, 44 are output to the gear ratio detection means 46, and in this means 46, the apparent rotation speed ratios (N _T / N ₀ ) are calculated. The gear ratio (R) is calculated. Next, the calculated gear ratio signal is output to the change rate detecting means 48, and the change rate (ΔR) of the gear ratio (R) is calculated to calculate the gear ratio predicting means.
The result is output to 50, and the gear ratio predicting means 50 determines the apparent predicted gear ratio Re after the operation start delay time of the clutch C (high-speed stage frictional engagement element). The judgment signal of the gear ratio predicting means 50 is a control means 52 for outputting a drive signal to the first and second solenoid valves 30, 32.
The control means 52 controls the timing for engaging and releasing the clutch C and the band brake B ₁ .
That is, when the shift command signal is input to the control means 52 and the upshift signal from the low speed stage to the high speed stage is input in the engine braking state, that is, the state where the accelerator pedal is released, first the second solenoid valve is input. The release signal of the band brake B ₁ is output to 32, and after that, the engagement signal of the clutch C is output to the first solenoid valve 30 when the predicted gear ratio Re becomes less than or equal to the gear ratio of the high speed stage by the gear ratio prediction means 50. It is about to do.

The operation of the shift control device 10 of the present embodiment having the above configuration will be described based on the flow chart of FIG. still,
This flow chart is executed every predetermined time, for example, every 5 msec, and shows the processing after the shift up signal from the low speed stage to the high speed stage is output in the engine braking state.

Therefore, in such a flow chart, first, step 100
Therefore, the release signal of the band brake B ₁ is output to the second solenoid valve 32. At this time, the gear train 12 is idling and the throttle opening is zero, so the rotation speed ratio between the input and output shafts 16 and 18, that is, the apparent gear ratio changes as shown in FIG. . In the next step 101, the changing gear ratio (R = N _T / N ₀ ) is calculated, and in the next step 102, the gear ratio change rate (ΔR) is calculated. This rate of change (ΔR) is calculated by storing the previously calculated gear ratio and calculating the difference between this gear ratio and this gear ratio. Next, at step 103, the change rate (Δ
R) is used, the gear ratio reached after the engagement signal of the clutch C is issued to the first solenoid valve 30 until the engagement of the clutch C is actually started, that is, after the operation start delay time of the clutch C is reached. Predict Re. This predicted gear ratio Re is a hardware delay time (from hydraulic pressure supply to clutch C).
Is actually engaged) and the processing timing of the program are taken into consideration. If K is a constant determined by these time lags, (Re = current gear ratio−ΔR ·
K) is required. Note that the time lag constant K is K = 100/5 = 20 because the processing timing of the program is 5 msec when the hardware delay is 100 msec, and the hydraulic fluid temperature is set to the hardware delay time. It is desirable to consider.

In the next step 104, it is judged whether or not the predicted gear ratio (Re) is less than or equal to the preset gear ratio (Ro) at the high speed stage. And Re has not reached Ro yet (NO)
In the case, the flow proceeds to step 105, the current gear ratio is stored as the previous gear ratio, and then the flow ends. On the other hand, if it is determined in step 104 that Re has reached Ro (YES), the process proceeds to step 106 and the first solenoid valve 3
The clutch C engagement signal is output to 0, and the flow ends.

Therefore, in this embodiment, when the clutch C engagement signal is output, when the actual gear ratio (R) has not yet reached the high speed gear ratio (Ro) (P ₁ point in FIG. 5). Done,
When the clutch C is securely engaged, by predicting the gear ratio (Re), the predetermined gear ratio (Ro) (5th
(P ₀ point in the figure). Therefore, when the clutch C is engaged and the high speed is set, the gear ratio on the bite and the gear ratio set by the gear train are matched or substantially matched. Therefore, gear shift shock can be prevented or greatly reduced even during shift up in the engine braking state.

By the way, in the case of a conventional engine, as disclosed in Japanese Patent Laid-Open No. 56-50232, fuel cut is performed during deceleration under certain conditions to improve exhaust gas purification performance and fuel efficiency. There is something. When the engine 20 having the fuel cut function is used in this embodiment, it is determined that the predicted gear ratio (Re) has reached the high speed gear ratio (Ro) at step 104 of the flow chart (YES). After that, prohibit changing fuel cut control,
For example, if the fuel cut is made during the upshift, the recovery of the fuel cut is prohibited and the fuel cut state is continued. By prohibiting the change of the fuel cut control in this manner, it is possible to prevent the predicted gear ratio (Re) after the clutch C is instructed from being changed.

It goes without saying that the gear train of the automatic transmission in which the shift control device 10 of the above-described embodiment is used is not limited to that shown in FIG.

As described above, in the shift control device for an automatic transmission according to the present invention, when the shift-up is performed in the engine braking state, the low-speed friction engagement element is first released, and then the high-speed friction engagement is performed. The gear ratio of the gear train after the operation start delay time of the coupling element is predicted, and when the predicted gear ratio reaches the gear ratio of the high speed stage, the instruction to engage the friction engagement element for the high speed stage is issued. When the apparent gear ratio reaches the set value for the high speed stage, the high speed stage friction engagement element is substantially engaged. Therefore, when the gear train is set to the high speed stage, the apparent gear ratio is also the set value of the high speed stage, and the gear ratio difference between the two becomes zero or extremely small. Therefore, the torque is smoothly introduced, and it is possible to prevent or significantly reduce the shift shock when the engine is in the brake state and is shifted up to the high speed stage.

[Brief description of drawings]

FIG. 1 is a block diagram showing a concept of a shift control device for an automatic transmission according to the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of a shift control device according to the present invention, and FIG. 3 is a shift according to the present invention. FIG. 4 is a schematic configuration diagram showing an embodiment of a gear train of an automatic transmission in which the control device is used, FIG. 4 is a flow chart showing an example of processing for executing a control program of the gear change control device of the present invention, and FIG. It is a characteristic view of a gear ratio change controlled by the shift control device of the present invention. 10 ... Shift control device, 12 ... Gear train, 16 ... Input shaft, 18 ... Output shaft, 20 ... Engine, 22 ... Torque converter, 30 ... First solenoid valve (hydraulic actuator for high speed stage) , 32 …… Second solenoid valve (low-speed hydraulic actuator), 40 …… Controller, 42 ……
Input shaft rotation speed detection means, 44 ... Output shaft rotation speed detection means,
46 …… Gear ratio detection means, 48 …… Change rate detection means, 50 ……
Gear ratio predicting means, 52 ... Control means.

Claims (1)

(57) [Claims] 1. A friction engagement element for a low speed stage, which is hydraulically actuated and fastened at a low speed stage and released at a high speed stage, and a friction engagement element for a high speed stage released at a low speed stage and fastened at a high speed stage. In the automatic transmission in which the hydraulic fluid pressure of each of these friction engagement elements is controlled by the hydraulic actuators for low speed and high speed driven by the output signal, A person for detecting the number of revolutions respectively, an output number of revolutions detecting means, and a gear ratio detecting means for detecting an apparent gear ratio from the ratio of the number of input revolutions and the number of revolutions of output obtained by the input number of revolutions detecting means; The change rate detecting means for detecting the change rate of the gear ratio based on the detection value of the gear ratio detecting means, and the gear detected by the change rate detecting means when shifting up from the low speed stage to the high speed stage to the engine braking state. Friction for the high speed stage based on the ratio of change ratio Gear ratio predicting means for predicting the gear ratio of the engagement element after the operation start delay time, and release of the low speed friction engagement element to the low speed hydraulic actuator in response to a shift command from the low speed to the high speed. Control for outputting a signal and outputting a fastening signal for the high-speed stage frictional engagement element to the high-speed stage hydraulic actuator when the predicted gear ratio of the gear ratio predicting means reaches a gear ratio of the high-speed stage or less A means for controlling a shift of an automatic transmission, comprising: