JPH0781629B2 - Line pressure control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a line pressure control device for an automatic transmission, and more particularly to a device for appropriately controlling the line pressure during gear shifting.

(Prior Art) An automatic transmission has various friction elements (clutch, brake, etc.) of a speed change gear mechanism, which are selectively hydraulically actuated by line pressure to select a predetermined shift speed and change the actuating friction element. Shift to the gear position of.

For this reason, if the line pressure is too high, the transitional engagement capacity of the friction element becomes excessive and a large shift shock occurs, and if the line pressure is too low, the transitional engagement capacity of the friction element becomes too small and the friction element slips. As a result, the service life is shortened. Therefore, it is necessary to properly control the line pressure. For example, in the past, "Automatic Transmission RE4RO1A Type Maintenance Manual" (A261CO7) issued by Nissan Motor Co., Ltd. in March 1987 was used.
As described in (1), the line duty is controlled by determining the drive duty of the line pressure control solenoid based on the engine throttle opening based on different table data during shifting and non-shifting.

However, in such a conventional line pressure control device, when the line pressure control solenoid has product variations or when the characteristics change over time, or when the friction elements have product variations, the friction material ages. When a change occurs, in the former case the line pressure deviates from the proper value even with the same solenoid drive duty, and in the latter case the line pressure is not the proper value for the friction element even if it is controlled as intended. However, due to excess or deficiency of the line pressure, a large shift shock or a shortened life of the friction element may occur.

By the way, for example, as shown in FIG. 10, in the case where the automatic transmission of the above document shifts the shift solenoid from ON to OFF at an instant t ₁ due to the decrease of the engine throttle opening degree, an upshift shift from the first speed to the second speed As can be seen, when the line pressure is low, the second speed selective pressure, which is based on this line pressure, rises as shown by the solid line and the corresponding friction element is engaged and advanced, and the input / output speed ratio N _T / of the transmission gear mechanism is increased. The gear ratio represented by N _O N _T : input speed, N _O : output speed changes from the 1st speed equivalent value to the 2nd speed equivalent value as shown by the solid line, and the transmission output torque becomes as shown by the solid line. In contrast to this, when the line pressure is high, the operation waveform is as shown by the dotted line. Therefore, it is possible to determine from the time during which the gear ratio N _T / N _O is changing, that is, the inertia phase time T, whether the line pressure is an appropriate value in consideration of the above-mentioned variations and changes over time. From this point of view, the present applicant has previously described in Japanese Patent Application No. 62-327452 the input rotation speed and the output rotation speed of the transmission gear mechanism of the automatic transmission described above by the input rotation sensor and the output rotation sensor, respectively. Detecting, based on the signals from these sensors, the inertia phase time measuring means measures the time during which the gear ratio represented by the ratio between the input and output rotational speeds changes, and the line pressure adjusting means We have proposed a line pressure control device that controls the line pressure during the shift so that the inertia phase time becomes a target value.With such a device, it is possible to constantly perform line pressure control that matches the actual conditions of the automatic transmission. It is possible to avoid the occurrence of a large shift shock and the reduction of the life of the friction element due to the excess and deficiency of the line pressure.

(Problems to be Solved by the Invention) The inventors of the present application, however, have found the following points to be improved while further researching the above-mentioned device.

In other words, the transitional engagement capacity of the friction element of the automatic transmission governed by the vehicle is determined by whether the engine is applying power to the automatic transmission even if the engine throttle opening is the same. On the contrary, it depends on whether the engine is being powered by the automatic transmission or not in the power-off state, and therefore the measured inertia phase time also depends on whether it is in the power-on state or in the power-on state. It becomes different with the same throttle opening.

However, the conventional line pressure control device described above sets the target value of the inertia phase time only in accordance with the type of shift and the throttle opening so as to be suitable for the shift in the power-on state. In the device, learning control is performed even with the measured value of the inertia phase time at the time of shifting near the throttle opening fully closed so that the power-on state and the power-off state alternate, and as a result There was a possibility that it would not be possible to sufficiently prevent the occurrence of shock.

The present invention provides an apparatus that advantageously solves such problems.

(Means for Solving the Problems) As shown in FIG. 1, a line pressure control device for an automatic transmission according to the present invention selectively hydraulically operates various friction elements of a speed change gear mechanism by line pressure so that a predetermined speed is established. Of the input speed sensor and the output speed sensor of the speed change gear mechanism of the automatic transmission in which the speed change gear is changed to another speed stage by changing the friction element to be operated. Detecting each, based on the signals from those sensors, the inertia phase time measuring means measures the inertia phase time, which is the time during which the gear ratio represented by the ratio between the input and output speeds is changing, A line pressure control device for an automatic transmission, wherein a pressure adjusting means controls the line pressure during the shift so that the inertia phase time reaches a target value. Power-off signal output means for outputting a signal indicating that the time-measured shift is a shift including a power-off state; and the inertia phase of the line pressure adjusting means based on a signal from the power-off signal output means. Control regulation means for regulating the control of the line pressure during shifting based on time, is provided.

(Operation) In such a device, the transmission gear mechanism selectively hydraulically operates various friction elements by the line pressure to select a predetermined shift speed, and the supply power is increased / decreased and output at this shift speed. Then, the transmission gear mechanism is shifted to another gear by changing the friction element that is hydraulically operated.

During this shift, the input rotation sensor and the output rotation sensor detect the input rotation speed and the output rotation speed of the transmission gear mechanism, respectively, and the inertia phase time measuring means determines the variable gear based on the signals from both sensors. The inertia phase time, which is the time during which the gear ratio represented by the ratio between the input and output speeds of the mechanism is changing, is measured. Then, the line pressure adjusting means controls the line pressure during shifting so that the inertia phase time becomes the target value.

On the other hand, the power-off signal output means outputs a signal indicating that the shift in which the inertia phase time is measured is a shift including a power-off state, and the control regulation means is based on the signal from the power-off signal output means. , The learning control of the line pressure adjusting means based on the inertia phase time is regulated.

Therefore, according to this device, even if there is product variation in the line pressure control element or characteristics change over time, or if there is product variation in the friction element or friction material change over time, these It is possible to perform line pressure control that takes into account individual differences and changes over time in automatic transmissions, and it is possible to avoid the occurrence of large shift shocks and shortened friction element life due to excess or deficiency of line pressure. Since the learning control is performed only when the machine shifts without including the power-off state, erroneous learning due to the value in the power-off state being included in the measurement value of the inertia phase time is prevented, and the line during shifting is prevented. Pressure control can always be done properly.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing.

FIG. 2 shows a power train control system of an automobile incorporating a device of an embodiment of a line pressure control device of the present invention, 1 is an electronically controlled fuel injection engine, 2 is an automatic transmission, 3 is a differential gear, and 4 is a drive. The wheels.

The engine 1 includes an engine control computer 5, which includes a signal from an engine rotation sensor 6 for detecting an engine speed N _E , a signal from a vehicle speed sensor 7 for detecting a vehicle speed V, and an engine throttle opening TH. The signal from the throttle sensor 8 for detecting, the signal from the intake air amount sensor 9 for detecting the engine intake air amount Q, etc. are input. The computer 5 determines the fuel injection pulse width T _F on the basis of these input information and commands it to the engine 1 or supplies an addition timing control signal (not shown) to the engine 1. The engine 1 is supplied with an amount of fuel according to the fuel injection pulse width T _P, and operates by burning this fuel in synchronism with the rotation of the engine.

Further, the automatic transmission 2 includes a torque converter 10 and a speed change gear mechanism 11 in a tandem, and inputs engine power to the input shaft 12 via the torque converter 10. The input rotation of the transmission to the shaft 12 is accelerated and decelerated according to the selected speed of the transmission gear mechanism 11 to reach the output shaft 13, from which the drive gear 4 is passed through the differential gear 3 to drive the vehicle. it can.

Here, the speed change gear mechanism 11 incorporates various friction elements (not shown) such as clutches and brakes that determine the transmission path (gear stage) from the input shaft 12 to the output shaft 13, and these various friction elements are used for line pressure. It is assumed that the hydraulic pressure is selectively actuated by P _L to select a predetermined shift speed, and that the shift to another shift speed is performed by changing the friction element to be actuated.

For this shift control, here is a computer for shift control.
14 and control valve 15 are provided. Computer
14 selectively turns on shift control shift solenoids 15a and 15b in the control valve 15 and selectively selects line pressure to various friction elements so that a corresponding shift stage is selected by a combination of ON and OFF of these shift solenoids. Supply P _L to control shift control. The shift control computer 14 also controls the line pressure control duty solenoid 16 in the control valve 15 by the drive duty D to control the line pressure P _L in the control valve 15 (the line pressure increases as the duty D increases). It shall be controlled as intended by the invention. A signal from the vehicle speed sensor 7 and a signal from the throttle sensor 8 are input to the computer 14 for the shift control and the line pressure control, respectively, and a signal from an input rotation sensor 17 for detecting the rotation speed _NT of the shaft 12 and Number of rotations of shaft 13
Inputs the signal from the output rotation sensor 18 for detecting the N _O, further, the idle switch 19 which in conjunction with the throttle valve engine throttle opening degree TH becomes ON when near the fully closed
The signal I _{S from is} also input.

Then, the computer 14 executes the control programs shown in FIGS. 3 to 5 to perform the line pressure control and the shift control.

First, the line pressure control program of FIG. 3 which is repeatedly executed by the timed interrupt will be described. In step 30, it is checked whether or not a gear change is in progress depending on whether a flag FLAG1 described later is 1 or not. As a result, if non-shifting (FLAG1 = 0), step 3
At 1, a table lookup is performed for the line pressure control solenoid drive duty D corresponding to the throttle opening TH from the duty table 1 for non-shifting, which has the characteristics as shown by the solid line A in FIG. Then step 32
Then, the drive duty 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, if the result of the above check is that the gear is in the middle of shifting (FLAG1 = 1), then in step 33, it differs depending on the type of gear shifting such as gear stage, upshift / downshift, etc. This is also shown by the dotted line B in FIG. 6 in RAM. The line pressure control solenoid drive duty D corresponding to the throttle opening TH is looked up from the characteristic shift duty table 2 and then in step 34, the shift is particularly likely to cause a shift shock due to an excessive line pressure. It is checked whether or not it is a shift shift, and if it is not an upshift as a result, the drive duty D is output to the solenoid 16 as it is in step 32 in the apparatus of this example. On the other hand, in the case of the upshift gear shift, in step 35, the line pressure corresponding to the throttle opening TH is calculated from the correction amount table shown in FIG. Control solenoid drive duty correction amount ΔD
After that, in step 36, D + ΔD is output to the solenoid 16 to control the line pressure P _L to a value for shifting.

Next, the shift control and line pressure control solenoid drive duty correction amount control of FIG. 4, which is also repeatedly executed by the timed interrupt, will be described. First, in step 40, FLAG1 is set to 1
It is checked whether or not gear shifting is in progress, and if gear shifting is not in progress (FLAG1 = 0), in step 41, a combination of vehicle speed V and throttle opening TH is supported based on a predetermined normal gear shifting pattern. Determines the required shift speed.

In the next step 42, it is checked whether or not the gear shift should be performed depending on whether or not the requested gear is different from the currently selected gear,
If the result is that gear shifting is to be performed, then in step 43, FLAG1 = 1 is set to indicate that gear shifting is in progress, and the solenoids 15a and 15b are O
Switch N, OFF to execute the shift to the required shift stage,
In the following step 44, signal whether the idle switch 19 is ON
If the idle switch 19 is ON, the flag is checked by I _S , and in step 45, FLAG3 = 1 is set to indicate that the engine state during gear shifting includes the power-off state, and then step 4
If the idle switch is not turned on in step 44, the process proceeds to step 46 with FLAG3 = 0.

When the gear shift is in progress (FLAG1 = 1) in step 43, steps 41 to 43 are skipped in the next control, but steps 44 and 45 are executed during the gear shift. Of course, FLAG3 = 1 even when the power-on state changes to the power-off state during gear shifting.

In step 46, the timer T ₁ for measuring the shift time is incremented (stepped), and in the next step 47, it is checked whether or not the inertia phase is in progress. In this check, the gear ratio represented by the input / output speed ratio N _T / N _O of the speed change gear mechanism 11 is changed from the gear ratio corresponding to the gear stage before the gear shift to the gear ratio corresponding to the gear stage after the gear shift. It is determined that the inertia phase is in progress while the direction is changing. Then, here, the timer T ₂ is incremented (stepped) in the step 48 during the inertia phase, and the step 48 after the inertia phase is skipped, whereby the inertia phase time is measured in the timer T ₂ .

In the next step 49, it is checked whether or not the inertia phase is completed (shift is completed), and if it is not completed, the program is terminated as it is, and if it is completed, the step is completed.
At 50, the flack FLAG1 is reset to 0 in response to the end of the shift, and at the same time, the flack FLAG1 for executing the learning control for correcting the data of the correction amount table in the RAM.
Set FLAG2 to 1.

In this way, while the gear shifting is completed and the gear shifting is not performed thereafter, the control proceeds to step 51 through steps 40 to 42,
Since FLAG2 = 1 is set as described above, step 52 is selected and the previous data of the line pressure control solenoid drive duty correction amount ΔD shown in FIG. 7 is corrected and updated by the following learning control.

In step 52, the learning control subprogram shown in FIG. 5 is executed. First, in step 60, it is checked whether FLAG3 = 1 or not. If FLAG3 = 1 is not satisfied, the immediately preceding shift is only in the power-on state. Step from gear change
Proceed to 61 to check whether the last shift was an upshift. If the shift is not the upshift, the learning control is not performed as described above, and the process ends. On the other hand, if the shift is the upshift, the timer T ₁ , that is, whether the shift time is equal to or greater than the predetermined value T _1S is determined in step 62. To check.
Line pressure control solenoid drive duty D + Δ during shifting
The time measured by the timers T ₁ and T ₂ for D% is as shown by the solid line in FIG. 8 for the case of upshift gear shifting in the power-on state, and the line pressure control solenoid drive duty is T ₁ ≧ T _1S When the line pressure is extremely small, for example, in the area indicating α, the line pressure is extremely low, so the rising portion of the selection pressure shown in FIG. 10, the so-called shelf portion, is too low overall, and the shelf portion ends. At that time, the frictional element is rapidly engaged due to the rapid increase in the selective pressure, resulting in an out-of-shelf shift as shown by the dotted line α in FIG. 9 and the shift shock becomes extremely large (solid line β in FIG. 9, The chain line γ is the operation waveform when the solenoid drive duty is the value indicated by the same sign in FIG. 8). To prevent this out-of-shelf shifting, step ₁ T ₁
When it is determined that ≧ T _1S , the line pressure solenoid drive duty correction amount ΔD corresponding to the throttle opening TH at the time of gear shift is looked up from the correction amount table corresponding to the type of gear shift in step 63. Then, in the subsequent step 64, the correction amount ΔDS is greatly increased by 2%, and in the subsequent step 65, the table data in the RAM is rewritten to the correction amount ΔD so that the T ₁ ≧ T _1S region is quickly escaped.

In the T ₁ > T _1S region, there is no such concern, so the correction amount ΔD
In step 66, the target value of the inertia phase time corresponding to the line pressure preferable for preventing shift shock and shortening the life of the friction element during shift in the power-on state (type of shift and throttle opening _T2S is looked up from the inertia phase time target value table in RAM, and in step 37, the line corresponding to the throttle opening TH is calculated from the correction amount table corresponding to the type of gear shift described above. The pressure control solenoid drive duty correction amount ΔD is looked up, and in step 68 the inertial phase time T ₂ is compared with the target value T _2S .

Then, as a result of the comparison in step 68, when T ₂ matches T _2S , the table data in the RAM of the correction amount ΔD is not changed and used as it is for the line pressure control during the next shift.
However, when T ₂ > T _2S , the line pressure is too low and the life is shortened due to the sliding of the friction element. Therefore, by executing steps 69 and 70, the correction amount Δ
The table data in the RAM of D is increased by 0.2% and used for line pressure control during the next shift. Therefore, during the next line pressure control, the line pressure control solenoid drive duty D + ΔD
Is increased by 0.2% compared to the previous time, and the line pressure can be increased by that amount, and the line pressure can be brought close to an appropriate value to avoid shortening the life of the friction element. On the other hand, when T ₂ <T _2S , the line pressure is too high and a large shift shock is generated due to the excessive engagement capacity of the friction element.
By executing 70, the correction amount ΔD corresponding to the type of shift
The table data in the RAM of is reduced by 0.2% and used for line pressure control during the next shift. Therefore, the line pressure control solenoid drive duty D + ΔD at the time of the next line pressure control is reduced by 0.2% from the previous time and the line pressure can be reduced by that amount, and the line pressure can be brought close to an appropriate value to prevent a large shift shock. be able to.

On the other hand, if FLAG3 = 1 in step 60, the measured T
The value of ₂ is during shifting including the power-off state, while the inertia phase time target value T _2S in this embodiment is suitable for shifting only in the power-on state as described above. In addition, for example, in the power-off upshift at a low vehicle speed, the transitional engagement point of the friction element can be small, so that the inertia phase time T ₂ is in the power-on state as shown in FIG. 8 even at the same throttle opening. In order to prevent erroneous learning, the table data of the correction amount ΔD is not corrected. In step 72, FLAG3 is cleared to 0, the subprogram is terminated, and the process returns to step 52.

Then, thereafter, in step 53, FLAG2 is reset to 0, the values of the timers T ₁ and T ₂ are reset to 0, and the next measurement is awaited.

By repeating such an operation (learning control), the line pressure solenoid drive duty correction amount ΔD is the line pressure control solenoid drive duty D + ΔD during gear shifting, and the line pressure is an appropriate value (inertia) irrespective of individual difference of the automatic transmission and aging. Continue to correct the phase time T ₂ to a value that makes it the target value T _2S ), and control the line pressure during shifting to an appropriate value that will not cause a reduction in the friction element life or a large shift shock under any circumstances. be able to.

Moreover, according to the device of this example, the inertia phase time target value suitable for the shift in the power-on state is used for the learning control, and the learning control is not performed in the inertia phase time measured during the shift including the power-off state. It is possible to prevent erroneous learning due to a difference in engine state at the time of gear shift and always control the line pressure during gear shift appropriately.

Although the present invention has been described above based on the illustrated example, the present invention is not limited to the above-described example. For example, learning control is performed not only in the case of upshifting but also in downshifting, and whether or not the learning control is possible. You may make it discriminate.

(Effect of the invention) Thus, according to the line pressure control device of the present invention, the learning control is performed only when the automatic transmission shifts without including the power-off state, so that the measured value of the inertia phase time indicates the power-off state. It is possible to prevent erroneous learning due to the inclusion of the value in (1) and always control the line pressure during gear shifting properly.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a 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 present invention device, and FIGS. 3 to 5 are shift control computers in the same example. 6 is a flow chart showing a line pressure control and shift control program of FIG. 6, FIG. 6 is a characteristic diagram of a line pressure control solenoid drive duty, and FIG. 7 is a momentary RAM regarding a correction amount of the duty.
8 is a diagram illustrating the data in FIG. 8, FIG. 8 is a diagram showing the relationship of the timer measurement time with respect to the line pressure control solenoid drive duty during shifting, and FIG. 9 is the solenoid drive duty of α, β, γ in FIG. FIG. 10 is a gear shift operation time chart showing a situation of occurrence of inertia phase during gear shift. 1 ... Electronically controlled fuel injection engine 2 ... Automatic transmission 3 ... Differential gear 4 ... Drive wheels 5 ... Engine control computer 6 ... Engine speed sensor 7 ... Vehicle speed sensor 8 ... Throttle sensor 9 ... … Intake air amount sensor 10 …… Torque converter 11 …… Shift gear mechanism 14 …… Shift control computer 15 …… Control valves 15a, 15b …… Shift control shift solenoid 16 …… Line pressure control duty solenoid 17 …… Input rotation sensor 18 …… Output rotation sensor 19 …… Idle switch

Claims (1)

[Claims] 1. An automatic control system in which various friction elements of a speed change gear mechanism are selectively hydraulically actuated by line pressure to select a predetermined speed step, and a gear to be operated is changed to another speed step by changing the operating friction element. The input rotation sensor and the output rotation sensor detect the input rotation speed and the output rotation speed of the transmission gear mechanism of the transmission, respectively, and based on the signals from these sensors, the inertia phase time measuring means determines the input / output rotation speed. The inertia phase time, which is the time during which the gear ratio represented by the ratio between the numbers is changing, is measured, and the line pressure adjusting means controls the line pressure during the shift so that the inertia phase time reaches a target value. In the line pressure control device, a power-off signal output that outputs a signal indicating that the shift in which the inertia phase time is measured is a shift including a power-off state Force control means, and control control means for controlling the control of the line pressure during the shift of the line pressure adjusting means based on the signal from the power-off signal output means, based on the inertia phase time. A feature of the automatic transmission line pressure control device.