JP3265800B2 - Control device for automatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission having a fluid transmission with a lock-up clutch and a continuously variable transmission, which controls the speed ratio of the continuously variable transmission in relation to the locked-up engagement state. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, in an automatic transmission having a fluid transmission with a lock-up clutch and a continuously variable transmission, when a control device controls the speed ratio of the continuously variable transmission,
Generally, control is performed such that the speed ratio of the continuously variable transmission is always set to the maximum value at the time of starting.

[0003]

When such control is performed, the driver or a passenger may be abruptly sensed when starting.
Alternatively, the ride comfort may be impaired by giving a jerky feeling when traveling on a congested road. Also, after the vehicle starts, when the vehicle speed is relatively low and the speed ratio of the torque converter (= input / output rotation speed ratio e = transmission input shaft rotation speed (also converter output shaft rotation speed) Nin / engine rotation speed Ne) is small. When the lock-up clutch is engaged, the inertia energy is released as the engine speed decreases,
Lock-up engagement shock may occur, which may impair ride comfort.

On the other hand, in order to solve the lock-up engagement shock, a control device disclosed in Japanese Patent Application Laid-Open No. 63-192629 has been proposed. This control device performs stepless speed change such that the actual input speed matches the target input speed of the continuously variable transmission calculated based on the traveling state of the vehicle (so that the speed difference between the two approaches zero). When controlling the speed ratio of the machine, the target input rotational speed is corrected in a direction in which the rotational speed difference decreases based on the input rotational speed of the fluid transmission. However, in the conventional example described in this publication, an operation of changing the speed ratio (downshift operation) is performed when the speed ratio of the continuously variable transmission is the maximum value, such as at a low vehicle speed immediately after starting, and the like. It is not possible to increase the transmission input shaft rotation speed to reduce the difference from the engine rotation speed. Problems arise.

According to the present invention, the speed ratio of the continuously variable transmission is set to a value lower than the maximum speed ratio of the continuously variable transmission by a predetermined amount when starting, and the speed ratio is set to the maximum value in accordance with the progress of the lock-up engagement. It is an object of the present invention to solve the above-described problem by continuously controlling in a direction that matches the speed ratio.

[0006]

SUMMARY OF THE INVENTION To this end, the present invention relates to an automatic transmission having a fluid transmission with a lock-up clutch and a continuously variable transmission, wherein the lock-up clutch is engaged after starting. The speed ratio of the continuously variable transmission is set to a value lower than the maximum value by a predetermined amount when starting, and the ratio of the transmission output shaft rotation speed to the engine rotation speed when the lockup clutch is not engaged and the maximum speed of the continuously variable transmission are set. When the difference from the gear ratio becomes equal to or less than the value corresponding to the slip of the fluid transmission when the fluid transmission is substantially in the coupling state, the engagement of the lock-up clutch is started,
During the engagement transient control of the lock-up clutch, the speed ratio of the continuously variable transmission is controlled such that the ratio of the transmission output shaft speed to the engine speed matches the maximum speed ratio of the continuously variable transmission. It is characterized by having made it.

[0007]

According to the present invention, the speed ratio of a continuously variable transmission of an automatic transmission having a fluid transmission with a lock-up clutch and a continuously variable transmission is controlled as follows. That is, at the time of starting, the speed ratio of the continuously variable transmission is set to a value lower than the maximum value by a predetermined amount, and the ratio of the transmission output shaft rotation speed to the engine rotation speed when the lock-up clutch is not engaged and the continuously variable transmission When the difference from the maximum gear ratio becomes equal to or less than the value corresponding to the slip of the fluid transmission when the fluid transmission is substantially in the coupling state, the engagement of the lock-up clutch is started and the lock is started. The speed ratio of the continuously variable transmission is continuously controlled in a direction to match the maximum speed ratio in accordance with the progress of the up-fastening. As described above, when the speed ratio of the continuously variable transmission is changed from the speed ratio lower than the maximum speed ratio by a predetermined amount to the maximum speed ratio side, even if the engine speed decreases at the start of the engagement of the lock-up clutch, the speed is maintained. The input shaft speed of the stepless transmission can be increased, and the speed difference between the input shaft speed and the engine speed of the continuously variable transmission can be reduced. For this reason, Japanese Patent Application Laid-Open No.
It is possible to prevent the ride comfort from deteriorating due to the lock-up engagement shock as in the conventional example of Japanese Patent Application Laid-Open Publication No. H11-209,878.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a vehicle to which a control device for an automatic transmission according to a first embodiment of the present invention is applied.
In the figure, 1 indicates an engine, 2 indicates a torque converter, and 3 indicates a continuously variable transmission.

The engine 1 has a throttle opening measuring device (throttle sensor) 4 for measuring the throttle opening Tvo.
Is provided. The output shaft 5 of the engine 1 is a torque converter 2
To join. The output shaft 5 of the engine 1 is provided with an engine speed measuring device (engine speed sensor) 6 for measuring the engine speed Ne. The torque converter 2
A lock-up clutch 7 for directly connecting the pump impeller side and the turbine runner side is built in the converter. The output side of the torque converter 2 is connected to the transmission input shaft 8 of the continuously variable transmission 3, and the transmission input shaft 8 is configured to measure an input shaft rotation speed Nin of the continuously variable transmission 3 ( An input shaft speed sensor 9 is provided. As the continuously variable transmission 3, a V-belt type continuously variable transmission or a toroidal type continuously variable transmission is used. The continuously variable transmission 3 is provided on the transmission output shaft 10 of the continuously variable transmission 3.
An output shaft rotation speed measuring device (output shaft rotation speed sensor) 11 for measuring the output shaft rotation speed Nout is provided.

A lock-up control device 12 is provided for controlling the engagement of the lock-up clutch 7 of the torque converter 2, and a speed ratio control device 13 is provided for variably controlling the speed ratio of the continuously variable transmission 3. The gear ratio control device 13 includes a throttle opening Tvo, an engine speed Ne, an input shaft speed Nin of the continuously variable transmission 3, an output shaft speed Nout of the continuously variable transmission 3, which are input from each of the measuring devices. By executing the control program of FIG. 2 based on the lock-up flag FL / U indicating the lock-up state input from the lock-up control device 12, the gear ratio control of the continuously variable transmission 3 targeted by the present invention is performed. Do. Further, the lock-up control device 12 controls the throttle opening Tvo, the engine speed Ne, the input shaft speed Nin of the continuously variable transmission 3 and the output shaft speed Nout of the continuously variable transmission 3 which are input from each of the measuring devices. By executing the control program shown in FIG. 3 based on the above, the engagement control of the lock-up clutch 7 of the torque converter 2 is performed.

Next, a description will be given of a control program of FIG. 2 which is repeatedly executed at predetermined intervals. First step 5
At step 1, the throttle opening Tvo, the engine speed Ne, the input shaft speed Nin and the output shaft speed Nout of the continuously variable transmission 3 are read, and at the next step 52, the speed ratio e of the torque converter 2 is calculated as e = It is calculated by Nin / Ne. Next, at step 53, the lock-up control device 12 reads the lock-up flag FL / U obtained by executing the control program shown in FIG. The lock-up flag FL / U is a flag indicating the state of the lock-up clutch 7, and takes a value of 0 when the lock-up clutch 7 is in the non-engaged state, 1 when the engagement is in the transition state, and 2 when the engagement is in the completed state. .

In the next step 54, it is determined whether or not the state of the lock-up flag FL / U is 0. If the lock-up flag FL / U is 1 or 2, the control proceeds to step 55, where the lock-up flag FL is determined. It is determined whether the state of / U is 1 or not. If the state of the lockup flag FL / U is 0 in step 54, the control proceeds to step 56. If the lock-up flag FL / U is 1 in step 55, the control proceeds to step 57, and if it is 2, the control proceeds to step 58. Eventually, step 56 is selected in the lock-up non-engagement state where the lock-up flag FL / U becomes 0, and step 57 is selected in the lock-up engagement transition state in which the lock-up flag FL / U becomes 1 and the lock-up flag FL is set. Step 58 is selected in the lock-up engagement completed state where / U becomes 2.

In step 57, Nin * is replaced with Nin *
= Nout / (e · imax). Where i
max is the maximum gear ratio of the continuously variable transmission 3, for example, ima
Set x = 5. In step 56, the target transmission input rotation speed Nin * of the continuously variable transmission 3 is set to Nin * = N
out / ist. Here, ist is the speed ratio of the continuously variable transmission at the time of starting, and ist = 4.5, for example.
Thus, the value is set to a value slightly smaller than the maximum speed ratio imax.

In step 58, Nin * is obtained by searching a map illustrated in FIG. 4 in which Nin * is represented by a function f (Tvo, Nout) using the throttle opening Tvo and the output shaft speed Nout as parameters.
Ask for *. The map of FIG. 4 shows each throttle opening (Tvo
= 0/8, 4/8, and 8/8) are illustrated in a superimposed manner.
It includes a portion corresponding to the maximum speed ratio imax of the continuously variable transmission, a portion corresponding to the throttle opening Tvo, and a portion corresponding to the minimum speed ratio imin of the continuously variable transmission.

In the next step 59, the above step 5
The speed ratio of the continuously variable transmission 3 is variably controlled so that the target transmission input rotation speed Nin * determined in steps 6, 57, and 58 is achieved, and the control cycle ends.

Next, a description will be given of a control program shown in FIG. 3 which is repeatedly executed at predetermined intervals. First step 6
In step 1, it is determined whether the state of the lock-up flag FL / U is 2 or not. If the lock-up flag FL / U is other than 2 (lock-up non-engagement state or lock-up engagement transitional state), the control proceeds to step 62. If it is 2 (the lockup engagement completion state), the control skips steps 62 to 71 and immediately proceeds to step 72. In step 62, the engine speed Ne, the input shaft speed Nin of the continuously variable transmission 3, and the output shaft speed Nout are read. In the next step 63, the ratio ipt of the output shaft speed Nout to the engine speed Ne is ipt. = Nout / Ne, and the input / output rotational speed difference ΔN of the torque converter 2 is calculated by ΔN = Ne−Nin.

In the next step 64, the engine speed N
It is determined whether the ratio ipt of the output shaft rotation speed Nout to e is equal to or less than the sum of α and the maximum speed ratio imax of the continuously variable transmission. In this determination, ipt is (imax +
If α) or less, the lock-up engagement transition state in which the difference between the two is small, the control proceeds to step 65, and the lock-up flag FL / U is set to FL / U = 1. Since the lockup is not engaged, the control proceeds to step 66 to set the lockup flag FL / U to FL / U = 0 and to set the lockup pressure P
After setting L / U to PL / U = 0, step 65 to step 7
Step 1 is skipped and the control immediately proceeds to step 73.
Note that α is a value (for example, α = 0.1) corresponding to the slip of the torque converter when the torque converter is substantially in the coupling state.

In step 67 following step 65, the input / output rotational speed difference ΔN of the torque converter 2 is set to a predetermined value Na.
(For example, 80 rpm). In this determination, if ΔN is larger than Na, the slip of the torque converter is large, so the control proceeds to step 68, and the lock-up pressure PL / U is increased to PL / U = Kp ×
ΔN + Ki × ΣΔN (Kp: proportional coefficient, Ki: integral coefficient), and the proportional integral control (feedback control) is performed based on the PL / U.
To skip step 72 and immediately control step 7
Proceed to 3. On the other hand, if ΔN is smaller than Na in the above determination, the slip of the torque converter is small.
Is calculated by PL / U = PL / U + dP, and the lamp control (open control) is performed by the PL / U. Note that dP is
This is a coefficient for lamp control, and is set to dP = 0.1, for example.

In a step 70 following the step 69, it is determined whether or not the lock-up pressure PL / U has exceeded an upper limit value Pmax (for example, 11). After U is set to FL / U = 2, the lock-up pressure PL / U is set to PL / U = P in step 72.
max. On the other hand, if the lock-up pressure PL / U does not exceed the upper limit value Pmax in the determination at the step 70, the control skips the steps 71 and 72 and immediately proceeds to the step 73. And step 6
6. At step 68, NO at step 70 and at step 73 following step 72, the lock-up pressure PL / U is output to the torque converter 2, and the control cycle is terminated. As a result, the lock-up pressure PL / U takes the value obtained in steps 66, 68, 70 and NO and in step 72.

Next, the operation of the first embodiment will be described with reference to FIGS. First, in the case of the conventional example shown in FIG. 7, while the engine speed Ne continues to increase in a quadratic curve as shown in the drawing, the lock-up complete release range is established, and the lock-up clutch is in the non-engaged state. Become. Until the engine speed Ne changes from rising to falling and coincides with the transmission input shaft speed Nin, the lock-up engagement transition control region is in effect, and the lock-up clutch is in the engagement transition state. After the engine speed Ne coincides with the transmission input shaft speed Nin, the lock-up complete engagement region is reached, and the lock-up clutch is fully engaged. Thus, at the time of start, the speed ratio of the continuously variable transmission is set to the maximum speed ratio i.
Since it is set to max, it is not possible to avoid the above-described deterioration in ride quality due to a sudden sense of departure.

On the other hand, in the present embodiment, by executing YES-step 56 of step 54 in FIG.
Since the speed ratio at the time of starting is set to ist smaller by a predetermined value than the maximum speed ratio imax of the continuously variable transmission as shown by a chain line in FIG. 5, the engine speed Ne changes as shown by the solid line in the figure. As a result, there is no possibility that the ride comfort is degraded due to the sudden feeling at the time of starting. In FIG. 5, when the lock-up clutch is in the non-engaged state, the throttle opening (T
vo = 1/8, 4/8, and 8/8), the relationship between the engine speed Ne and the transmission output shaft speed Nout is shown.

Further, in this embodiment, by executing YES-step 65 of step 64 in FIG. 3, the ratio ipt of the transmission output shaft rotation speed Nout to the engine rotation speed Ne when the lock-up clutch is not engaged. = No
When the difference between t / Ne and the maximum speed ratio imax of the continuously variable transmission becomes equal to or less than a predetermined value α, the engagement of the lock-up clutch is started. By executing YES in step 67-step 68 or NO in step 67-step 69, feedback control or open control of the lock-up clutch pressure PL / U is performed, and the ratio of the transmission output shaft rotation speed to the engine rotation speed ipt Is controlled to match the maximum speed ratio imax of the continuously variable transmission. Therefore, by this control, the engine speed N
e, the relationship between the transmission input shaft rotation speed Nin and the transmission output shaft rotation speed Nout, the lockup complete release region, the lockup engagement transient control region, and the lockup complete engagement region are improved as shown in FIG. In other words, the above-mentioned JP-A-63
There is no deterioration in ride quality due to the lock-up engagement shock as in the conventional example of JP-A-192629.

[0023]

As described above, the control device for the automatic transmission according to the present invention controls the speed ratio of the continuously variable transmission of the automatic transmission having the fluid transmission device with the lock-up clutch and the continuously variable transmission as described above. When starting, the speed ratio of the continuously variable transmission is set to a value lower than the maximum value by a predetermined amount, and the ratio of the transmission output shaft rotation speed to the engine rotation speed when the lockup clutch is not engaged and the continuously variable transmission When the difference from the maximum gear ratio of the machine becomes equal to or less than the value corresponding to the slip of the fluid transmission when the fluid transmission is substantially in the coupling state, the engagement of the lock-up clutch is started, Since the speed ratio of the continuously variable transmission is continuously controlled in accordance with the progress status of the lock-up engagement in a direction to match the maximum speed ratio, even if the engine speed decreases at the start of the engagement of the lock-up clutch, the speed is maintained. Step It is possible to increase the rotational speed of the input shaft of the speed machine, it is possible to reduce the rotational speed difference between input shaft speed and engine speed of the continuously variable transmission. for that reason,
It is possible to prevent the ride comfort from deteriorating due to the lock-up engagement shock as in the conventional example of JP-A-63-192629.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle to which a control device for an automatic transmission according to a first embodiment of the present invention is applied.

FIG. 2 is a flowchart illustrating a control program for speed ratio control of a continuously variable transmission that is repeatedly executed at predetermined intervals in the example.

FIG. 3 is a flowchart showing a control program of lock-up clutch engagement control that is repeatedly executed at predetermined intervals in the same example.

FIG. 4 is a diagram illustrating a map in which a target transmission input rotation speed is represented as a function of a throttle opening and a transmission output shaft rotation speed in the same example.

FIG. 5 is a diagram showing a relationship between an engine speed and a transmission output shaft speed at each throttle opening when the speed ratio control is performed in the same example.

FIG. 6 shows the relationship between the engine speed, the transmission input shaft speed, and the transmission output shaft speed at each throttle opening when the lock-up clutch engagement control is performed in the same example, and the lock-up completeness. It is a figure which shows a release area | region, a lockup engagement transient control area, and a lockup complete engagement area.

FIG. 7 shows a relationship between an engine speed, a transmission input shaft speed, and a transmission output shaft speed, a lockup complete release region, a lockup engagement transient control region, and a lockup complete engagement region in a conventional example. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Torque converter (fluid transmission) 3 Continuously variable transmission 4 Throttle opening degree measuring device 5 Engine output shaft 6 Engine speed measuring device 7 Lock-up clutch 8 Transmission input shaft 9 Input shaft speed measuring device 10 Transmission Output shaft 11 Output shaft rotation speed measuring device 12 Lock-up control p device 13 Transmission control device

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-172668 (JP, A) JP-A-5-26343 (JP, A) JP-A-63-303259 (JP, A) JP-A-63-63 192629 (JP, A) JP-A-5-332431 (JP, A) JP-A-63-121536 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 59/00-61 / 12 F16H 61/16-61/24 F16H 63/40-63/48 F16H 61/14

Claims (1)

(57) [Claims] 1. An automatic transmission having a fluid transmission with a lock-up clutch and a continuously variable transmission, wherein the lock-up clutch is engaged after the vehicle starts moving, wherein the speed ratio of the continuously variable transmission is set from a maximum value at the time of starting. The fluid transmission device is set to a value that is lower by a predetermined amount, and the difference between the ratio of the transmission output shaft rotation speed to the engine rotation speed when the lockup clutch is not engaged and the maximum speed ratio of the continuously variable transmission is approximately The engagement of the lock-up clutch is started at a point in time when the value becomes equal to or less than the value corresponding to the slip of the fluid transmission device when the coupling state is established, and the transmission for the engine speed during the engagement transient control of the lock-up clutch is performed. Controlling the speed ratio of the continuously variable transmission so that the ratio of the rotation speed of the output shaft matches the maximum speed ratio of the continuously variable transmission. Apparatus.