JPH0781626B2 - 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 control the line pressure appropriately. For example, in the past, “Automatic Transmission RE4R01A Type Maintenance Manual” (A261C0 issued by Nissan Motor Co., Ltd. in March 1987) was used.
As described in 7), the line pressure 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 changes occur, they cannot be dealt with, and in the former case the line pressure deviates from the proper value even with the same solenoid drive duty, in the latter case the line pressure is not the proper value for the friction element even if it is controlled as intended. In any case, however, it is inevitable that a large shift shock and a reduction in the life of the friction element will occur due to excess or deficiency of the line pressure.

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 from the first speed to the second speed is performed. 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, No: output speed changes from the first speed equivalent value to the second speed equivalent value as shown by the solid line, and the transmission output torque changes as shown by the solid line. On the other hand, 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 improvements while further researching the above device.

That is, for example, in the case where an upshift is performed from the first speed to the second speed immediately after the downshift is performed from the second speed to the first speed, the same friction element is actuated again at short intervals, and the friction Due to the residual hydraulic pressure in the element,
The inertia phase time of the upshift from the second speed to the second speed may be extremely short.

However, in the above device, the inertia phase time is always used for learning for the line pressure control, so even if the extremely short inertia phase time occurs, the learning for the line pressure control is performed. As a result, there is a possibility that the line pressure during gear shifting may be inappropriately controlled.

The present invention provides a device that advantageously eliminates such improvements.

(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, In a line pressure control device for controlling a line pressure during the shift such that the pressure adjusting means controls the inertia phase time to a target value, the shift to a predetermined shift stage and the predetermined shift From the shift speed to another shift speed, the shift interval measuring means for measuring the shift interval, and the measured shift interval are compared with a reference value set as a shift interval at which the influence of residual hydraulic pressure is eliminated. A control regulation unit that regulates the line pressure control during the shift based on the inertia phase time in the shift from the predetermined shift stage to another shift stage when the line pressure is less than the reference value. It is characterized by being provided.

(Operation) In such a device, the speed change 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 transmission gear mechanism based on the signals from both sensors. The inertia phase time, which is the time during which the gear ratio, which is represented by the ratio between the input and output speeds, is changing. 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 shift interval measuring means, the shift interval between the shift to the predetermined shift stage and the shift from the predetermined shift stage to another shift stage,
That is, the same friction element measures the interval at which the friction element is activated twice in succession, and the control regulating means changes the measured shift interval to
Compared with the reference value set as the shift interval at which the influence of the residual oil pressure is eliminated, and if the reference value is less than the reference value, the inertia phase time in shifting from the predetermined shift stage to another shift stage of the line pressure adjusting means is determined. Based on this, the control of the line pressure during the shift is restricted.

Therefore, according to this device, even if the line pressure control element is subject to variations in the product and the characteristics change over time, or if there is variation in the product in the friction element or the friction material changes 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 large shift shocks and shortened friction element life due to excessive or insufficient line pressure, as well as short intervals. If the inertia phase time becomes extremely short due to the influence of the residual hydraulic pressure due to the gear shift performed in
Since the line pressure control based on the inertia phase time is not performed, the control of the line pressure during the shift can always be properly performed.

(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 _P based on these input information and commands it to the engine 1, or supplies an ignition 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 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. For the shift control and the line pressure control, a signal from the vehicle speed sensor 7 and a signal from the throttle sensor 8 are input to the computer 14, and the rotation speed N _{T of the} shaft 12 is also input.
A signal from an input rotation sensor 17 for detecting the rotation speed and a signal from an output rotation sensor 18 for detecting the rotation speed N _O of the shaft 13 are input.

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

First, the line pressure control program of FIG. 3 which is repeatedly executed by the timed interrupt will be described. In step 20, 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 is in progress, in step 21, the line pressure control solenoid drive duty D corresponding to the throttle opening TH is looked up from the non-shifting table data as shown by the solid line A in FIG.
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 shifting is in progress, in step 23,
A table lookup is performed for the line pressure control solenoid drive duty D corresponding to the throttle opening TH from the table data for gear shift as shown by the dotted line B in FIG. 6, which varies depending on the type of gear shift such as gear stage, upshift / downshift, etc. Then
Next, at step 24, it is checked whether or not the shift is an upshift that is particularly prone to a shift shock due to excessive line pressure. If this is not the upshift, then in this example, at step 22, The drive duty D is output to the solenoid 16 as it is. On the other hand, in the case of the upshift gear shift, in step 25, the throttle control is performed from the data of the line pressure control solenoid drive duty correction amount as shown in FIG. Opening
Read the line pressure control solenoid drive duty correction amount ΔD corresponding to TH. After that, in step 26, 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, at step 30, a timer T ₃ for measuring the shift interval is incremented (advanced). Then, in the following step 31, it is checked whether FLAG1 is 1, that is, whether or not the gear is being changed. If the gear is not being changed, in step 32, the vehicle speed V and the throttle opening are determined based on a predetermined normal gear change pattern.
The required shift speed corresponding to the combination of TH is determined, and in the next step 33, it is checked whether or not the shift should be performed depending on whether or not the required shift speed is different from the currently selected shift speed. And, if it should be a result shifting, in step 34, reads the value of the timer T ₃ as the shift interval I, in the subsequent step 35, addition to the FLAG1 = 1 to indicate during shifting, a solenoid 15a, 15b of the O
By switching N and OFF, the shift to the required shift stage is executed. When the gear shift is being performed by this, steps 32 to 35 are skipped in the next control.

In step 36, the timer T ₁ for measuring the shift time is incremented (advanced), and in the next step 37, 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 (advanced) in step 38 during the inertia phase, and step 38 after the inertia phase is skipped, whereby the inertia phase time is measured by the timer T ₂ .

In the next step 39, it is checked whether or not the inertia phase has ended (end of gear shift). If not completed, the program ends as it is, and if completed, step
At 40, the flag FLAG1 is reset to 0 in response to the end of the shift, and the flag FLAG2 for executing the learning control for correcting the data in the RAM shown in FIG. 7 is set to 1, and the timer T ₃ is also set. It is reset to 0 corresponding to the end of gear shifting.

In this way, while the gear shifting is completed and the gear shifting is not performed thereafter, the control proceeds to step 41 through steps 30 to 33.
Since FLAG2 = 1 is set as described above, step 42 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 this step 42, the learning adequacy determining subprogram shown in FIG. 5 (a) and the learning control subprogram shown in FIG. 5 (b) are sequentially executed, and first, FIG. 5 (a).
FLAG1 and FLA in steps 50 and 51 of
Check G2. If FLAG1 = 0 and FLAG2 = 1, it means that the shift control is not in progress and the learning control is required to be executed, so the routine proceeds to step 52. Otherwise, the sub program is terminated and the routine proceeds to step 60.

In step 52, the shift interval I between the start of the shift immediately before the execution of this program and the end of the shift immediately before the program is the same friction element used for those shifts, and The reference value that is the shift interval at which the residual hydraulic pressure of the vehicle is sufficiently reduced so that it does not affect the inertia phase time of the subsequent shift.
It is checked whether or not I _S (for example, 1.0 sec) or more. As a result, if the shift interval I is the reference value I _S or more, step 53
In step 54, FLAG3 for permitting learning is set to 1 to perform learning control, and then FLAG2 is reset to 0 in step 54. When the shift interval I is less than the reference value I _S ,
Step 53 is skipped so that learning control is not performed, and the process proceeds to step 54.

Next, here, in step 60 in FIG.
Check if AG3 is 1 and as a result FLAG3 is 1
If not, learning is not permitted, so it ends, but FL
If AG3 = 1, it is checked in step 61 whether the immediately preceding shift was an upshift shift. If it is not an upshift, the learning control is not performed as described above, so the routine proceeds to step 67. On the other hand, if it is an upshift, the timer T _{1 in} step 62, that is, the shift time is a predetermined value.
Check if T _1s or more. Timer for line pressure control solenoid drive duty D + ΔD% during shifting
The measurement times of T ₁ and T ₂ are as shown in FIG. 8, and when the line pressure control solenoid drive duty is extremely small such as α in the region where T ₁ ≧ T _1S , the line pressure is Since it is extremely low, for example, the rising portion of the selective pressure shown in FIG. 10, that is, the so-called shelf portion is too low overall, and when the shelf portion is finished, the friction element is rapidly fastened due to the rapid increase in the selective pressure. Therefore, the out-of-shelf gear shift as shown by the dotted line α in FIG. 9 results in an extremely large shift shock (the solid line β and the chain line γ in FIG. 9 have the solenoid drive duty values of the same values in FIG. 8 respectively). Operating waveforms). In order to prevent this out-of-shelf shift, when T ₁ ≧ T _1S is determined in step 62, the correction amount ΔD corresponding to the shift type is determined in step 63.
Is increased by 2% to promptly escape from the T ₁ ≧ T _1S region.

In the T ₁ <T _1S region, the above concern does not exist, so step 64
Check the time measured by timer T ₂ , that is, the inertia phase time. When the inertia phase time T ₂ matches the target value (different for each type of shift and throttle opening) T _2S that corresponds to the line pressure that is preferable for preventing shift shock and reducing the life of the friction element, The data in the RAM for the correction amount ΔD in FIG. 7 is not changed and is 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 of the friction element is shortened due to the sliding of the friction element. Therefore, the execution of step 65 causes the RAM of the correction amount ΔD shown in FIG. The data in 0.2
% And used for line pressure control during the next shift. Therefore, at the time of 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 the life reduction of the friction element. You can
On the contrary, 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. Therefore, by executing step 66, the correction shown in FIG. 7 corresponding to the type of shift is performed. The data of the amount ΔD in the RAM is reduced by 0.2% and used for line pressure control during the next shift. Therefore, the line pressure control solenoid drive duty D + for the next line pressure control
ΔD is reduced by 0.2% from the previous time and the line pressure can be reduced accordingly, and the line pressure can be brought close to an appropriate value to prevent a large shift shock.

After that, in step 67, FLAG3 is reset to 0, and then this subprogram is ended and the process returns to step 43, whereby steps 61 to 67 are skipped until the next shift is completed and learning is permitted. Then, in step 43, the values of the timers T ₁ and T ₂ are reset to 0, and the next measurement is awaited.

By repeating this 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 set to an appropriate value (inertia) regardless of individual differences of the automatic transmission and changes with time. 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, when the gear shift interval I is short and the friction element in the latter gear shift is actuated earlier due to the influence of the residual hydraulic pressure in the first gear shift, when the inertia phase time becomes extremely short, the inertia phase time is shortened. Since the learning control based on the time is not performed, the line pressure control during the shift can always be properly controlled.

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, the learning control is performed not only in the upshift but also in the downshift, and it is determined whether the learning control is possible. It may be done.

(Effects of the Invention) Thus, according to the line pressure control device of the present invention, when the inertia phase time becomes extremely short due to the influence of the residual hydraulic pressure due to the gear shifting performed at short intervals, Since the line pressure control based on the inertia phase time is not performed, the control of the line pressure during shifting can always be performed 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

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 shift interval measuring means for measuring a shift interval between a shift to a predetermined shift stage and a shift from the predetermined shift stage to another shift stage; The determined gear shift interval is compared with a reference value set as a gear shift interval at which the influence of the residual hydraulic pressure is eliminated, and when the shift value is less than the reference value, the line pressure adjusting means changes from the predetermined gear stage to another gear stage. A line pressure control device for an automatic transmission, comprising: a control restricting unit that restricts control of a line pressure during a shift based on an inertia phase time in the shift.