JPH0523878Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a line pressure control device for an automatic transmission, and particularly to a device for appropriately controlling line pressure during gear shifting.

(Prior art) Automatic transmissions selectively hydraulically actuate various friction elements (clutches, brakes, etc.) in a transmission gear mechanism using line pressure to select a predetermined gear, and then change the friction elements that operate with a gear change command. By doing so, the gear can be shifted to another gear.

Therefore, if the line pressure is too high, the transient engagement capacity of the friction element becomes too large, resulting in a large shift shock, and if the line pressure is too low, the transient engagement capacity of the friction element becomes too small, causing the friction element to slip. This leads to a decrease in service life. Therefore, it is necessary to properly control the line pressure, and conventionally, for example, as described in "Automatic Transmission RE4R01A Model Maintenance Manual" (A261C07) published by Nissan Motor Co., Ltd. in March 1987, line pressure was controlled properly during gear shifting. The drive duty of the line pressure control solenoid is determined based on the engine throttle opening degree from the table data corresponding to Fig. 5 (A is for non-shifting, B is for shifting), although it differs depending on whether the gear is being shifted or not. It controlled the line pressure.

(Problem to be solved by the invention) However, in such conventional line pressure control devices, when there are product variations in the line pressure control solenoid and characteristics change over time, even if the drive duty of the same solenoid is The line pressure during gear shifting drops below the appropriate value, causing a delay in engagement of the friction elements.
This causes a so-called off-shelf shift, which will be explained below, and causes a large shift shock.

That is, FIG. 6 shows the automatic transmission of the above-mentioned document turning off the corresponding shift solenoid at instant _t1 from 1 to 2.
In the shift operation time chart when an upshift shift command is received, a case will be described in which the line pressure control solenoid drive duty D is determined as described above and the duty D as shown by the dotted line in Fig. 6 is applied to the line pressure control solenoid. . Assuming that the line pressure is below the appropriate value due to product variations in the line pressure control solenoid and changes in characteristics over time, the 2nd speed selection pressure using this line pressure as the source pressure is as shown in Figure 6. As shown by the dotted line, a rise delay occurs, and the engagement of the corresponding friction element is delayed. For this reason, the friction element is engaged after the stroke of the shift shock prevention accumulator (off-shelf shift), and the input/output rotational speed ratio of the shift gear mechanism is
The gear ratio expressed as N _T /N _O (N _T : input rotation speed, N _O : output rotation speed) is the first as shown by the dotted line in Figure 6.
When the speed equivalent value changes to the second speed equivalent value, the transmission output torque generates a large peak torque as shown by the dotted line in the figure, and a large shift shock occurs.

(Means for Solving the Problems) The present invention provides that the above-mentioned phenomenon can be grasped from the time from the shift command instant t ₁ to the instant when the gear ratio change starts, as indicated by T _G in FIG. Since this can be prevented by increasing line pressure, as shown in the concept in Figure 1, when a predetermined gear is selected by selectively hydraulically operating multiple friction elements of the transmission gear mechanism using line pressure, a transmission command is issued. In an automatic transmission configured to shift to another gear stage by changing a friction element that operates when a transmission occurs, the input rotation sensor detects the input rotation speed of the transmission gear mechanism; and 17, the output rotation of the transmission gear mechanism an output rotation sensor 18 for detecting the number of rotations; and an inertia phase sensor 18 for detecting that the gear ratio expressed by the ratio between the input and output rotation speeds has started to change toward the gear ratio after shifting based on the signals from these sensors. start detection means 25, a line for increasing the line pressure during gear shifting after the set time has elapsed if the inertia phase start detection means does not detect the start of the inertia phase even after a set time has elapsed since the shift command; A pressure adjusting means 46 is provided.

(Operation) The transmission gear mechanism selects a predetermined gear stage by selectively hydraulically operating a plurality of friction elements using line pressure.
At this gear stage, the supplied power is increased/decelerated and output. When a speed change command is issued due to a change in operating conditions, the speed change gear mechanism shifts to another speed by changing a hydraulically operated friction element.

During this time, the input rotation sensor and the output rotation sensor are respectively detecting the input rotation speed and output rotation speed of the speed change gear mechanism. The inertia phase start detection means detects, based on the signals from these two sensors, that the gear ratio represented by the ratio between the input and output rotational speeds of the transmission gear mechanism has begun to change toward the post-shift gear ratio. If this means does not detect the start of the inertia phase even after a set time has passed since the shift command, the line pressure adjusting means increases the line pressure during the shift. Therefore, even if the line pressure during a gear shift drops below the appropriate value due to variations in the line pressure control solenoid or changes over time, this system reliably prevents the gear shift from becoming off-shelf due to an increase in the line pressure. , it is possible to prevent a large shock from occurring.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

Figure 2 shows the powertrain control system of an automobile incorporating the line pressure control device of the present invention, in which 1 is an electronically controlled fuel injection engine, 2 is an automatic transmission, 3 is a differential gear, and 4 is a driving wheel. .

The engine 1 is equipped with an engine control computer 5, and this computer has a number of engine rotational speeds.
A signal from the engine rotation sensor 6 that detects N _E ,
A signal from the vehicle speed sensor 7 that detects the vehicle speed V, a signal from the throttle sensor 8 that detects the engine throttle opening TH, a signal from the intake air amount sensor 9 that detects the engine intake air amount Q, etc. are input. . The computer 5 determines the fuel injection pulse width T _P based on this input information and applies it to the engine 1.
It also supplies an ignition timing control signal (not shown) to the engine 1. The engine 1 is supplied with fuel in an amount corresponding to the fuel injection pulse width T _P and is operated by burning this fuel in time with the rotation of the engine.

The automatic transmission 2 includes a torque converter 10 and a speed change gear mechanism 11 in tandem, and inputs engine power to an input shaft 12 via the torque converter 10. The transmission input rotation to the shaft 12 is the transmission gear mechanism 1.
The output shaft 13 is increased or decelerated according to the selected gear position of 1, and is connected to the differential gear 3 from this output shaft.
The vehicle reaches the drive wheels 4 through the vehicle, and the vehicle can be driven.

The speed change gear mechanism 11 has an input shaft 12 to an output shaft 13.
It incorporates various friction elements (not shown) such as clutches and brakes that determine the transmission path (gear stage) to the
These various friction elements are selectively hydraulically operated by line pressure P _L to select a predetermined gear stage, and
In response to a shift command, a shift to another gear stage is performed by changing the friction element to be operated.

For this speed change control, a speed change control computer 14 and a control valve 15 are provided. The computer 14 selectively turns on the shift solenoids 15a and 15b for speed change control in the control valve 15, and turns on and off these shift solenoids.
Shift control is controlled by selectively supplying line pressure P _L to various friction elements so that the corresponding gear stage is selected depending on the OFF combination. The shift control computer 14 also controls the duty solenoid 16 for line pressure control in the control valve 15 using the driving duty D to control the line pressure P _L in the control valve 15 (the line pressure increases as the duty D increases). shall be controlled as intended by the present invention. For the above-mentioned speed change control and line pressure control, the computer 14 receives a signal from the vehicle speed sensor 7 and a signal from the throttle sensor 8, respectively, as well as a signal from the input rotation sensor 17 that detects the rotation speed N _T of the shaft 12. and rotation speed of shaft 13
A signal from the output rotation sensor 18 that detects N _O is input.

The computer 14 executes the control programs shown in FIGS. 3 and 4 to perform speed change control and line pressure control.

First, to explain the shift control shown in FIG. 3 which is repeatedly executed by a regular interrupt, first, in step 20, it is checked whether or not a shift is in progress by checking whether FLAG1, which will be described later, is 1 or not. If the gear is not being shifted, a required gear position corresponding to the combination of vehicle speed V and throttle opening TH is determined based on a predetermined normal shift pattern in step 21. In the next step 22, it is checked whether or not a shift is to be made based on whether the requested gear is different from the currently selected gear. If the gear should not be shifted, a timer _T1 (described later) is cleared in step 23, and if the gear should be shifted (at the time of a gear shift command), FLAG1 is set to 1 to indicate that the gear is being shifted in step 24, and the solenoid 15a, 15b is turned on and off to execute the shift to the above-mentioned required gear position. Furthermore, when the gear is being changed (FLAG1=1), step 21,
Skip 22 and 24.

After executing step 24 and during the subsequent gear change, it is checked in step 25 whether or not the inertia phase is in progress (corresponding to inertia phase start detection means). For this check, change gear mechanism 1
The period during which the gear ratio represented by the input/output speed ratio N _T /N _O of 1 changes from the gear ratio corresponding to the gear before shifting to the gear ratio corresponding to the gear after shifting is called inertia. It is determined that the patient is suffering from an AIDS. If the inertia phase is not in progress, timer _T1 is incremented (stepped forward) in step 26, and by skipping step 26 after the inertia phase, timer _T1 starts the inertia phase from the shift command. Measure the time until.

In step 27, it is checked whether this time is greater than or equal to the set time T _S , and if T ₁ ≧ T _S , then in step 28 FLAG2 is set to indicate this.
is set to 1, but if T ₁ < _TS , skip step 28 (keep FLAG2 = 0). step
In step 29 following 25, 27 or 28, the gear ratio
Whether the inertia phase has ended (or has shifted) depends on whether N _T /N _O has reached the gear ratio after shifting.
Check whether or not. When the inertia phase is completed, the above FLAG1 and
Reset FLAG2.

Next, to explain the line pressure control shown in FIG. 4, which is repeatedly executed by regular interrupts, in step 40, it is checked whether the above-mentioned flag FLAG1 is 1 or not to see if the gear is being shifted. If the gear is not being shifted, in step 41, the line pressure control solenoid drive duty D corresponding to the throttle opening TH is looked up from the table data for non-shifting shown by the solid line A in FIG. 5, and then in step 42, this drive duty is D
is output to the solenoid 16 to control the line pressure P _L to the normal value for non-shifting.

On the other hand, during gear shifting, in step 43, the throttle opening is determined from the gear shifting table data indicated by the dotted line B in Figure 5.
Table up the line pressure control solenoid drive duty D corresponding to TH. Next, in step 44, it is checked whether the above-mentioned FLAG2 is 1, that is, whether the inertia phase is not started even after the set time T _S has elapsed since the shift command. If FLAG2 = 0, there is no problem with normal line pressure control, so in step 42 the duty D looked up in step 43 is
is output to the solenoid 16, thereby increasing the line pressure.
Controls P _L to the normal value for shifting.

For example, as shown in FIG. 6, the time T G from the shift command instant t ₁ until the gear ratio N _T /N _O starts to change toward the gear ratio after the shift is long, and the timer _{T 1}
If the measured time is longer than the set time T _S , FLAG2 becomes 1 at step 28 in Figure 3 at the instant _t2 when the T _S time has elapsed since the shift command, so the steps in Figure 4 are repeated until the end of the shift. 44 selects step 46. In this step 46, the duty D looked up in step 43 is set to a fixed value (for example, 10
%) and outputs it to the solenoid 16 (corresponding to line pressure adjustment means). Therefore, in the case of Fig. 6, the duty D is increased by 10% from instant _t2 until the end of the shift, as shown by the solid line.
By correspondingly increasing the line pressure P _L , the second speed selection pressure can be raised to the solid line level. Therefore, the delay in engagement of the corresponding friction element (off-shelf shift) is eliminated, and the engagement is performed during the stroke of the accumulator for preventing shift shock, as is clear from the change in the gear ratio N _T /N _O shown by the solid line. As a result, shift shock can be prevented by setting the transmission output torque to a low peak torque as shown by the solid line.

(Effects of the invention) Thus, as described above, the device of the present invention is configured to increase the line pressure if the inertia phase does not start even after the set time elapses from the shift command.
Even if the above phenomenon occurs when the line pressure falls below the appropriate value due to variations in the line pressure control solenoid or changes over time, shifting off the shelf due to insufficient line pressure during shifting will not occur, and the resulting shift shock will be prevented. can do.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the line pressure control device of the present invention, Fig. 2 is a control system diagram of an automobile power train showing an embodiment of the device of the present invention, and Figs. 3 and 4 are for shift control in the same example. A flowchart showing a computer speed change control program and a line pressure control program, Fig. 5 is a characteristic diagram of line pressure control solenoid drive duty, and Fig. 6 is a speed change of an automatic transmission with and without using the device of the present invention. This is an operation time chart. 1...Electronically controlled fuel injection engine, 2...Automatic transmission, 3...Differential gear, 4...
Drive wheel, 5... engine control computer,
6...Engine rotation sensor, 7...Vehicle speed sensor,
8... Throttle sensor, 9... Intake air amount sensor, 10... Torque converter, 11... Speed change gear mechanism, 14... Speed change control computer, 15
...Control valve, 15a, 15b...Shift solenoid for speed change control, 16...Duty solenoid for line pressure control, 17...Input rotation sensor, 18...Output rotation sensor.

Claims (1)

[Scope of Claim for Utility Model Registration] A plurality of friction elements of a speed change gear mechanism are selectively hydraulically activated by line pressure to select a predetermined gear, and when a speed change command is issued, by changing the activated friction elements. In an automatic transmission configured to shift to another gear, an input rotation sensor detects the input rotation speed of the transmission gear mechanism, an output rotation sensor detects the output rotation speed of the transmission gear mechanism, and from these sensors. an inertia phase start detection means for detecting that the gear ratio represented by the ratio between the input and output rotational speeds has started to change toward the gear ratio after shifting based on the signal; and after a set time has elapsed from the shifting command. The present invention is also characterized in that, if the start of the inertia phase is not detected by the inertia phase start detection means, line pressure adjustment means is provided for increasing the line pressure during gear shifting after the set time has elapsed. Automatic transmission line pressure control device.