JP3055346B2 - Selective shock reduction 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 the operation of a starting friction element which is activated (engaged) when a manual valve of an automatic transmission is switched from a non-traveling range to a traveling range. The present invention relates to an apparatus for suitably performing control so that the accompanying select shock is reduced.

[0002]

2. Description of the Related Art In an automatic transmission, a corresponding shift speed is selected by selectively operating various friction elements (friction clutch, friction brake, etc.), and a shift to another shift speed is possible by changing the operating friction element. is there. Accordingly, there is also a starting friction element that is engaged when the driver switches the manual valve from the non-traveling range to the traveling range in order to drive from a stopped state, and when the starting friction element is engaged, automatic shifting is performed. The machine switches from the power transmission disabled state to the power transmission enabled state. At this time, the drag torque of the torque converter provided in the preceding stage of the automatic transmission is transmitted to the drive wheels of the vehicle, so that a so-called select shock occurs.

In order to reduce this select shock, conventionally, as shown in FIG. 6, engagement of a starting friction element which is engaged when switching from a non-traveling range (N range) to a traveling range (D range) (instantaneously t ₀ ). The line pressure P _L
A device has been proposed in which the value Po is reduced from the normally determined value Po to Ps, and is gradually returned to the normal value Po after the set time Ts.

[0004]

However, in such a select shock mitigation device, the hydraulic pressure of the starting frictional element is controlled to be open. Therefore, the hydraulic pressure control pattern shown in FIG. And product variations,
Furthermore, when the fluid is no longer suitable due to a change in the viscosity of the working fluid or the like, the desired select shock reduction effect cannot be achieved.

The present invention recognizes the fact that the select shock is affected by the time required for engaging the starting friction element, and learns and controls the hydraulic fluid pressure of the starting friction element so that the required time for engagement becomes the set time. By doing so, it is an object to solve the above-mentioned problem. The present invention further enables the completion of the engagement of the starting friction element required for measuring the required engagement time to be determined by a transmission input rotation speed signal from an easily available and inexpensive rotation sensor, and furthermore, the determination is made. It is an object of the present invention to accurately perform the operation based on a transmission input rotation speed signal from a rotation sensor.

[0006]

SUMMARY OF THE INVENTION To this end, a select shock mitigation device for an automatic transmission according to the present invention is hydraulically actuated when a manual valve is switched from a non-travel range to a travel range as shown in FIG. In the automatic transmission provided with a starting friction element that puts the automatic transmission in a power transmission state, the input rotation sensor that detects the transmission input shaft rotation speed and the start friction element start engaging. The engagement start detecting means for detecting, and the transmission input shaft rotation speed detected by the input rotation sensor after the engagement start detection means detects the start of engagement of the starting friction element, the lower limit value of the input rotation sensor detectable. A time measuring means for measuring a time Ta required to decrease to Nia; and the input rotation sensor when the engagement start detecting means detects the engagement start of the starting friction element. Detection was signed at the start of the input rotational speed Ni
b, a required engagement time Tb required from the start to the end of engagement of the starting friction element using the detectable lower limit Nia of the input rotation sensor and the measurement time Ta.
Is estimated by the calculation of Tb = Ta × (Nib / Nia), and the moment when the required fastening time Tb elapses after the engagement start detecting means detects the start of engagement of the starting friction element, the engagement of the starting friction element is determined. From the time when the end of engagement of the starting friction element is determined by the time when the end of engagement of the starting frictional element is determined after the engagement start determining means and the engagement start detecting means detects the start of engagement of the starting friction element. And starting hydraulic pressure control means for modifying the starting hydraulic pressure of the starting friction element so as to decrease the required hydraulic pressure when the required time Tb is shorter than the set time and to increase the hydraulic pressure when the required time Tb is longer than the set time. It is a feature.

[0007]

When the manual valve is switched from the non-traveling range to the traveling range in order to travel, the automatic transmission is engaged with the starting friction element by the hydraulic pressure, and is in a power transmission state.

At the time of this range switching, the timing means detects the transmission input shaft rotation speed detected by the input rotation sensor after the engagement start detection means detects the start of engagement of the starting friction element. The time Ta required to decrease to the lower limit value Nia is measured. On the other hand, the engagement completion determination means includes an engagement start input rotation speed Nib detected by the input rotation sensor when the engagement start detection means detects the engagement start of the starting friction element, and a detectable lower limit Nia of the input rotation sensor. And the measurement time Ta,
The required fastening time Tb required from the start of the start friction element to the end of the engagement is defined as Tb = Ta × (Nib / Ni
It is estimated by the calculation of a), and the moment when the calculated required engagement time Tb elapses after the engagement start detecting means detects the engagement start of the starting friction element is determined as the end of the engagement of the starting friction element. The starting hydraulic pressure control means includes a starting friction element for a period from when the engagement start detecting means detects the start of engagement of the starting friction element to when the engagement end determination means determines that the engagement of the starting friction element is completed. Is decreased so that the required engagement hydraulic pressure Tb is decreased when the required engagement time Tb is shorter than the set time, and increased when the required time Tb is longer than the set time.

As a result, the working fluid pressure at the time of switching the range of the starting friction element is learned and controlled so that the element ends its operation just after the set time, so that the select shock can be reduced. And since this control is learning control, the change with time of the automatic transmission,
Even if there is a variation in the product or even a change in the viscosity of the hydraulic fluid, the control that takes these into consideration is automatically executed, and the above-mentioned select shock is always reduced without being affected by these. The effect can be achieved.

In addition, the completion of the engagement of the starting friction element required for measuring the engagement required time Tb can be determined by the transmission input rotation speed signal from the input rotation sensor which is easily available and inexpensive. Therefore, an expensive and difficult-to-obtain torque sensor is not required, which is very advantageous in terms of cost. In addition, even if the input rotation sensor cannot detect the transmission input shaft rotation speed less than the detectable lower limit Nia, the transmission input shaft rotation speed is set to 0 as described above.
Thus, the instant at which the engagement of the starting frictional element is completed can be accurately determined, and the above operation and effect can be reliably achieved at low cost.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows an embodiment of the select shock mitigation apparatus of the present invention, wherein 1 is an engine as a power source, 2 is an automatic transmission, and the automatic transmission 2 is, for example, a "RE4R01A type full range electronically controlled automatic issued by Nissan Motor Co., Ltd. This is almost the same as that described in the "Transmission Maintenance Manual" (A261C07), and the rotational power from the engine 1 is rotated according to the selected shift speed and transmitted to wheels (not shown). In the automatic transmission 2,
Although not shown in the drawings, as apparent from the above document, the forward clutch hydraulically operated at the first forward speed and the reverse clutch hydraulically operated at the reverse speed correspond to the starting friction elements, respectively. Switching from N) range to automatic forward drive (D) range (N → D select)
The case where the select shock at the time when the forward clutch is operated in accordance with the above is reduced will be described as an example.

The shift control of the automatic transmission 2 and the select shock reduction effect aimed at by the present invention are performed by a control valve 3, which includes shift solenoids 4 and 5 and a forward clutch pressure duty solenoid 6. The control valve 3 further includes a manual valve (not shown), which is manually operated by the driver using the select lever 7 for the parking (P) range, the reverse driving (R) range, the neutral (N) range, and the automatic forward shifting (D). ) Range can be switched to the 2nd speed engine brake running (II) range or 1st speed engine brake running (I) range.

[0013] The P range and the N range are ranges in which all friction elements including the starting friction element of the automatic transmission are released to keep the automatic transmission in a state where power cannot be transmitted, thereby enabling parking and stopping of the vehicle. It is. Further, the R range is a range in which a friction element (reverse clutch) of the automatic transmission is engaged in order to achieve a power transmittable state in which the power of the engine 1 can be reversed and output. Further, in the D range, a friction element including a forward clutch is provided by a combination of ON and OFF of the shift solenoids 4 and 5 in order to bring the automatic transmission 2 into any of the four forward speeds so as to be able to transmit power. It is a range that is combined and concluded. Note that I
The I range and the I range are the same as the D range except that the highest gear is limited to a gear lower than the gear corresponding to the selected range so that engine braking can be obtained.

As is well known, all operations of the automatic transmission 2 are controlled by the regulated line pressure, and the engagement of the friction elements including the forward clutch and the reverse clutch is also performed by the line pressure. This line pressure is also controlled by a line pressure duty solenoid (not shown) in the control valve 3 via its drive duty.

The forward clutch pressure duty solenoid 6 controls the operating pressure of the forward clutch, which is a starting frictional element, as described below, using the above-mentioned line pressure as the original pressure, thereby reducing the select shock which the present invention aims at. The action shall be performed.

ON and O of the shift solenoids 4 and 5
The FF control and the duty control of the forward clutch pressure duty solenoid 6 are performed by the controller 8. Therefore, the controller 8 transmits a signal from the throttle opening sensor 9 for detecting the throttle opening TVO of the engine 1, Output shaft speed (vehicle speed) VSP
, A signal RNG from a range sensor 11 for detecting a selection range of the select lever 7 (manual valve), and an input rotation sensor 12 for detecting an input shaft rotation speed Ni of the automatic transmission 2. Signal,
And a signal from the pressure switch 13 that is turned on when the forward clutch pressure becomes equal to or higher than a set value indicating the end of precharge (rapid pressure supply during a loss stroke of the forward clutch).

The controller 8 performs a shift control (not shown) based on the input information and executes a control program shown in FIG. 3 to perform a forward shock pressure control for reducing the select shock which is the object of the present invention.

First, the outline of the shift control will be described. The controller 8 includes a throttle opening T detected by the sensors 9 and 10.
The optimum gear position for the current driving condition is determined from the VO and the vehicle speed VSP based on a preset shift pattern, and when the currently selected gear position is different from the optimal gear position, the ON / OFF of the shift solenoids 4 and 5 is determined. The automatic transmission 2 is shifted to this optimum gear by switching to correspond to the optimum gear.

Next, the forward clutch pressure control for reducing the select shock shown in FIG. 3 will be described with reference to FIGS. 4 and 5. This control program is executed every time the select lever 7 is switched from the non-traveling range N to the traveling range D. (N → D
This is executed each time a selection is made.

First, at step 21, it is checked whether or not the pressure switch 13 is ON, that is, whether or not precharging of the forward clutch has been completed. Until the precharging is completed, the precharging is continued at step 22. I do. The precharge during loss stroke from N → D select instant t ₀ in FIG. 5 to time t ₁ to initiate the forward clutch is actually concluded without causing engagement shock (selection shock), also a rapidly In order to ensure the operation of the forward clutch, it is advantageous to rapidly supply the operating pressure to the forward clutch, which means this rapid pressure supply. The end of the precharge can be detected by turning on the pressure switch 13.

[0021] When the precharge is completed at instant t ₁ in FIG. 5, control proceeds to step 23 and subsequent FIG. In step 23, the built-in timer T is reset to measure the elapsed time from the instant, and in the next step 24, the forward clutch pressure Pc is obtained by adding a constant reference pressure Pa and a pressure correction amount ΔP. A drive duty for achieving the forward clutch pressure Pc = Pa + △ P is commanded to the duty solenoid 6. Between the control such forward clutch pressure, until the instant t ₃ when the step 25 detects the engagement completion of the forward clutch (see FIG. 5),
continue.

Here, how the completion of engagement of the forward clutch is determined in step 25 will be described. Forward clutch starts to engagement until the completion of the (instant t ₁ in FIG. 5) (instant t ₃ in FIG. 5), the transmission output shaft torque, engine speed, and transmission input shaft speed Ni is Each changes with time as shown in FIG. Therefore, when the transmission input shaft rotation speed Ni becomes 0, it is considered that the engagement of the forward clutch is completed, and this may be determined. However, the input rotation sensor 12 in FIG.
When i is less than Nia, this cannot be detected. Therefore, as clearly shown in FIG. 4 in an enlarged manner, the transmission input shaft speed Ni at the forward clutch engagement start instant t ₁
reads b from the sensor 12, the forward clutch engagement start instant t _1, the transmission input shaft rotational speed Ni sensors 1
Time T until instant t ₂ to reach the lower detectable lower limit Nia of ₂
detects a from the timer T, the forward clutch engagement completion instant t ₃ from the forward clutch engagement start instant t ₁
Time (time required for the forward clutch to engage)
Tb is calculated by Tb = Ta (Nib / Nia).
Then, it is determined if the timer T is started to indicate this value Tb and forward clutch engagement completion instant t _3.

When it is determined in step 25 that the forward clutch is completely engaged, in step 26, the forward clutch pressure Pc is set to the same maximum value as the original line pressure, that is, the drive duty 100% is set to the solenoid. Output to 6.

Next, at step 27, the required time Tb for engaging the forward clutch is compared with a set time Ts. The set time Ts can be determined by, for example, an experiment by setting the shortest time as the set time Ts within a range in which the forward clutch engagement shock, that is, the N → D select shock does not cause any problem.

If Tb = Ts, the control is terminated as it is. If Tb <Ts, the forward clutch pressure Pc is too high and the select shock becomes so large that the pressure correction amount ΔP is increased by a predetermined amount in step 28. The pressure is reduced by α and updated, and the updated pressure correction amount ΔP is contributed to the calculation in step 24 from the next time. Conversely, Tb
If ≧ Ts, the forward clutch pressure Pc is too low, causing a delay in the selection operation. Therefore, in step 29, the pressure correction amount △ P is increased by a predetermined amount α and updated, and the updated pressure correction amount か らP contributes to the calculation in step 24.

Therefore, the forward clutch pressure Pc can be controlled so that the required time Tb for engaging the forward clutch becomes the set time Ts, whereby the N → D select shock can be reduced.

Since this control is a learning control, even if there is a change over time of the automatic transmission, a variation in the product, or a change in the viscosity of the hydraulic fluid, the control taking these into consideration is performed automatically. Thus, the above-described select shock reduction effect can be achieved at all times without being affected by these effects. Further, the completion of the forward clutch engagement required for measuring the forward clutch engagement required time Tb can be determined by the transmission input rotation speed signal from the input rotation sensor 12 which is easily available and inexpensive. is there. In addition, even if the input rotation sensor 12 cannot detect the transmission input shaft rotation speed less than the detectable lower limit value Nia, the starting friction at which the transmission input shaft rotation speed Ni becomes zero as described above. The instant at which the fastening of the elements is completed (the instant t _{3 in} FIG. 5) can be accurately determined, and the above-described effects can be reliably and inexpensively achieved.

[0028]

Thus, the select shock mitigation apparatus of the present invention is configured as described in claim 1, and the time required for fastening Tb required to complete the engagement after the start friction element starts the engagement. Measured, the fastening hydraulic pressure of the starting friction element during the period from the start of fastening to the end of fastening of the starting friction element is reduced when the required fastening time Tb is shorter than the set time, and increased when the required fastening time Tb is longer than the set time. Accordingly, the engagement hydraulic pressure at the time of switching the range of the starting friction element is learned and controlled so that the element just finishes the engagement operation in the set time, thereby reducing the select shock.

Since this control is a learning control, even if there is a change over time of the automatic transmission, a variation in the product, or a change in the viscosity of the hydraulic fluid, the control taking these into consideration is performed automatically. Thus, the above-described select shock reduction effect can be achieved at all times without being affected by these effects. In addition, when determining the completion of the engagement of the starting friction element necessary for measuring the engagement required time Tb, the input rotation speed Nib at the start of the engagement of the starting friction element and the transmission from the start of the engagement of the starting friction element are determined. From the time Ta required for the input shaft rotation speed to decrease to the lower limit Nia detectable by the input rotation sensor and the lower limit Nia detectable by the input rotation sensor, Ta × (Nib
/ Nia) to determine the required engagement time Tb of the starting friction element, and determine the instant when the required engagement time Tb has elapsed from the start of engagement of the starting friction element as the end of engagement of the starting friction element. The end determination of the engagement of the friction element can be determined based on the transmission input speed signal from the input rotation sensor, which is easily available and inexpensive. It is also very advantageous in terms of terms. In addition, even if the input rotation sensor cannot detect the transmission input shaft rotation speed less than the detectable lower limit value Nia, the starting friction element of the transmission input shaft rotation speed becomes 0 as described above. It is possible to accurately determine the instant of completion of the fastening, and to reduce the above operation and effect at low cost.
And it can be achieved reliably.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a select shock reduction device of the present invention.

FIG. 2 is a system diagram showing one embodiment of the select shock reduction device of the present invention.

FIG. 3 is a flowchart showing a select clutch reduction forward clutch pressure control program executed by the controller of the example.

FIG. 4 is a time series change time chart of a transmission input shaft rotation speed used for explaining a forward clutch engagement completion determination method in the control program.

FIG. 5 is a time chart showing a forward clutch pressure control mode according to the control program of FIG. 3;

FIG. 6 is an operation time chart of the conventional select shock reduction device.

[Explanation of symbols]

 Reference Signs List 1 engine 2 automatic transmission 3 control valve 4 shift solenoid 5 shift solenoid 6 forward clutch pressure duty solenoid 7 select lever 8 controller 9 throttle opening sensor 10 vehicle speed sensor 11 range sensor 12 input rotation sensor 13 pressure switch

Claims (1)

(57) [Claims] 1. An automatic transmission having a starting friction element which is engaged by hydraulic pressure to switch a power transmission state of an automatic transmission when a manual valve is switched from a non-travel range to a travel range. An input rotation sensor for detecting the number of rotations, an engagement start detecting means for detecting that the starting friction element has started engagement, and an engagement start detecting means for detecting the start of engagement of the start friction element. The transmission input shaft rotation speed detected by the input rotation sensor is lower than the detectable lower limit Nia of the input rotation sensor.
A time measuring means for measuring a time Ta required until the input rotation sensor Ni decreases the input start rotation speed Nib detected by the input rotation sensor when the engagement start detection means detects the engagement start of the starting friction element; Using the detectable lower limit value Nia of the rotation sensor and the measurement time Ta, calculation of the required engagement time Tb required from the start of the engagement of the starting friction element to the end of the engagement by Tb = Ta × (Nib / Nia). A fastening end determining means for determining that an instant when the required fastening time Tb has elapsed since the fastening start detecting means has detected the fastening start of the starting friction element is a time when the fastening of the starting friction element is finished, From the time when the engagement start detecting means detects the engagement start of the starting friction element to the time when the engagement end determination means determines the engagement end of the starting friction element, A starting hydraulic pressure control means for reducing the hydraulic pressure for engagement when the required time for coupling Tb is shorter than a set time and increasing the hydraulic pressure when the time required for engagement Tb is longer than the set time; Machine select shock mitigation device.