JP2920232B2 - Shift shock reduction device for automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift shock reduction device for reducing a shock generated during a shift in an automatic transmission for a vehicle, and more particularly to a shift shock reducing device that always obtains a good shift feeling. Related to learning control.

[Conventional technology]

Generally, in an automatic transmission, a plurality of clutches or brakes attached to a fixed element of a planetary gear are selectively engaged by operating hydraulic pressure to automatically perform shift control.
The engaged state of the clutch directly affects the shift shock. Therefore, as a countermeasure against shock, it is effective to suppress the rise of the operating hydraulic pressure of the clutch, but this causes a delay in shifting.

Therefore, it is desirable to speed up shifting while suppressing shock. As a countermeasure against this, a hydraulic pressure adjusting means such as an accumulator is provided in a circuit for operating hydraulic pressure to each clutch, and the rise of operating hydraulic pressure is changed stepwise. It has been proposed that the shelf pressure in the middle of the hydraulic characteristics is variably controlled depending on the operating state, so that the reduction of shock is emphasized at low load and the speed change is emphasized at high load.

A good shift feeling can be obtained by controlling the operating oil pressure by the accumulator, but this may be deteriorated due to variations in the operating oil pressure, the friction coefficient μ of the clutch, the engine torque, etc., and changes over time. For this reason, it is desired that especially the shelf pressure by the accumulator is always optimally corrected by learning the actual state of the shift shock, thereby keeping the shift shock reduced.

Conventionally, there is a prior art in Japanese Patent Application Laid-Open No. Sho 62-56656 regarding this type of shift shock reduction measure. Here, it is shown that a change in output shaft torque is detected using a torque sensor, and the fluid pressure is adjusted by evaluating the quality of a shift operation based on the torque fluctuation width.

[Problems to be solved by the invention]

By the way, in the above-mentioned prior art, a torque sensor is separately required and a change in torque must be accurately detected. In addition, since the determination is made only based on the fluctuation width of the output shaft torque, the fluctuation width is always controlled uniformly, and it is difficult to apply the present invention to a system that speeds up shifting according to load or the like.
Further, even if the magnitude of the shift shock can be determined, the shock occurrence timing is not detected, so that there is a risk of erroneous determination due to torque fluctuations other than the shift.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to accurately detect an actual shift shock state from the magnitude and timing of a shift shock without using a special sensor. It is an object of the present invention to provide a shift shock reduction device for an automatic transmission that can perform learning control so as to ensure a proper shift feeling.

[Means for solving the problem]

In order to achieve the above object, a shift shock reduction device for an automatic transmission according to the present invention includes an accumulator connected to an oil passage for operating hydraulic pressure to a shift clutch, and at least a control for an accumulator pressure oil passage on a back pressure side of the accumulator. In a hydraulic shift control system having a duty solenoid that variably controls the accumulator pressure with an electric signal from the unit,
A shift shock judging means for judging the magnitude of the actual shift shock based on the vehicle body acceleration, and an accumulator pressure correction amount learning means for correcting the accumulator pressure according to the length of the shift time until the shift shock occurs after the start of the shift. .

[Action]

Based on the above configuration, the rise of the operating oil pressure introduced to the shift clutch of the automatic transmission becomes smooth due to the accumulator pressure of the accumulator, and the clutch is quickly engaged with little shift shock to shift gears. The accumulator pressure is corrected by the accumulator pressure correction amount learning means from the actual shift shock and the shift time at the time of shifting,
The shift shock is corrected so that a low shift shock occurs at an appropriate shift time with respect to individual differences, aging, and the like. In this way, a good shift feeling is always obtained, and shift shock is effectively reduced.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, the power transmission control system of the hydraulic system is described by omitting the power train of the automatic transmission. Reference numeral 1 denotes a transmission clutch, which is a line pressure from a pressure regulating valve 3 for regulating a discharge pressure from an oil pump 2. The oil passage 4 communicates with the conversion clutch 1 via the manual valve 5 and the shift valve 6. A pilot pressure oil passage 9 having a shift solenoid 8 communicates with the shift valve 6. The shift valve 8 applies pilot pressure to the shift valve 6 by a shift solenoid 8 at a predetermined shift speed to perform a communication operation. It is designed to guide and engage.

As a countermeasure for shifting shock reduction, an accumulator 10 communicates with the line pressure oil passage 4 immediately before the shifting clutch 1.
The accumulator 10 has a spring 1 on one side of the piston 10a.
0b is energized, and the back pressure chamber 10c communicates with the accumulator control valve 12 via the accumulator pressure oil passage 11. A pilot pressure oil passage 9 having a duty solenoid 13 communicates with the control side of the accumulator control valve 12, and the accumulator pressure of the accumulator control valve 12 is controlled by the pilot pressure of the duty solenoid 13. 1. Adjust the shelf pressure of the working oil pressure.

Describing the electronic control system, it has a vehicle speed sensor 16 and a throttle opening sensor 17. The vehicle speed V of the vehicle speed sensor 16 and the throttle opening θ of the throttle opening sensor 17 are input to the shift control means 21 of the control unit 20, and a shift signal based on the shift pattern based on the vehicle speed V and the throttle opening θ is output to the shift solenoid 8. I do. The throttle opening .theta. Is input to the accumulator pressure setting means 22, and the accumulator pressure (shelf pressure) Pa provided before the clutch pressure Pc in the clutch operating hydraulic characteristics in FIG. (Proportionally).

Next, as a learning control system for shifting shock reduction, the vehicle speed V of the vehicle speed sensor 16 is converted into an analog value by the D / A converter 18 and input to the acceleration calculating means 23, and the vehicle speed V is differentiated to obtain the acceleration α. = Dv / dt. The acceleration α is input to the shift shock determination means 24, and the target acceleration amplitude α _d is set in advance by the target acceleration amplitude setting means 25 based on the vehicle speed V, the throttle opening θ, and the like at the time of gear shifting. _{d is} also input to the shift shock determination means 24. Here, since the amplitude α _P of the acceleration α coincides with the magnitude of the shift shock, as shown in FIG. 3, the amplitude α _P is compared with the target acceleration amplitude α _d and when α _P > α _d , It is determined that the shift shock is large.

Shift start signal of the shift shock signal and the shift control means 21 is input to the shift time calculation means 26, as shown in FIG. 3, the shift up acceleration amplitude peak value alpha _P after the shift command is generated time T Measure _S. The target type of shift in shift time setting means 27 (1 → 2,2-3), is preset target shift time T _d is the vehicle speed V and the throttle opening theta, the target shift time T _d and a transmission time by comparing the T _S to determine the length of the transmission time. These shift shock and shift time determination signals are input to the accumulator pressure correction amount learning means 28 to set a correction amount ± ΔP.

Here, when a shift shock of α _P > α _d occurs, T _S
In the case of < _Td , it can be determined that a shift shock occurs because the accumulator pressure Pa is too large and the shift is fast, and therefore, the correction amount -ΔP is set. On the other hand, T _S ≧ T _d
In the case of, it can be determined that the shift is slow because the accumulator pressure Pa is too small, so the correction amount ΔP is set. The correction amount ΔP is input to the accumulator pressure setting means 22, and the value of the accumulator pressure Pa stored in the RAM is corrected by ± ΔP.

In order to prevent an erroneous determination due to a change in the acceleration α on a rough road, there is provided a rough road traveling determination unit 29 to which the acceleration α and the shift signal are input. If the amplitude α _P at the time when a predetermined time has elapsed after the start of the shift is equal to or larger than the set value, it is determined that the road is bad, and the learning by the accumulator pressure correction amount learning means 28 is interrupted.

Next, the operation of the shift shock reducing device for an automatic transmission having such a configuration will be described.

First, the accumulator pressure Pa is set by the throttle opening θ in the engine operating state, and the duty solenoid 13 is set.
The duty pressure acts on the accumulator control valve 12 to control the back pressure chamber 10c of the accumulator 10 to the accumulator pressure Pa. Therefore, at the time of shifting, a shift signal is input to the shift solenoid 8 to shift the shift valve 6.
When the communication operation is performed, the line pressure of the line pressure oil passage 4 is introduced into the transmission clutch 1. At this time, the line pressure is also introduced into the accumulator 10 to operate the piston 10a.
Due to the change in the volume of the accumulator 10, the rise of the clutch operating oil pressure becomes smooth as shown in FIG. 2 and the shift shock is reduced. After the balance with the accumulator pressure Pa, the clutch operating oil pressure rises again and the shift clutch 1 And the shift is completed.

Here, when the load is low, the gear speed is shifted more smoothly by setting the shelf pressure of the clutch operating oil pressure together with the accumulator pressure Pa to be low. On the other hand, when the load is high, the accumulator pressure Pa increases and the speed is changed quickly.

At the time of such shift control, the flowchart of FIG. 4 is executed, and the accumulator pressure Pa is learned and controlled based on the actual state of the shift shock. That is, step S1
In step S101, the vehicle speed V is read.
Converted D / A, the acceleration alpha is calculated by differentiation of the vehicle speed V at step S102, and the amplitude alpha _p and the target acceleration alpha _d acceleration are compared in step S103. If α _P > α _d , it is determined that a shift shock has occurred, and the process proceeds to step S104. The shift time is determined by comparing the shift time T _S until the shift shock occurs after the start of the shift with the target shift time T _d. You. Thus, the actual magnitude and occurrence state of the shift shock are detected, and when the shift of T _S <T _d is fast, the process proceeds to step S105, where the accumulator pressure Pa is corrected to decrease by the correction amount −ΔP. For this reason, as shown in FIG.
Is slightly lowered in accordance with the correction amount -ΔP, and accordingly, the engagement of the transmission clutch 1 is delayed, and FIG.
As in the dashed, this case is also modified to that target acceleration alpha _d following lower shift shock occurs at substantially the target shift time T _d.

On the other hand, if the shift of T _S ≧ T _d is slow, the process proceeds to step S106, and the accumulator pressure Pa is corrected to increase by the correction amount ΔP. Therefore, as shown in Figure 2, shelf pressure is faster engagement of the shifting clutch 1 becomes slightly higher, as shown by the broken line of FIG. 5 (b), the target at substantially the target shift time T _d Again It is modified to one that acceleration alpha _d following low shock occurs.

In this way, by optimizing the smooth clutch engagement state by the accumulator pressure Pa, the shift shock is reduced, and a good shift feeling is always obtained.

In addition, when the fluctuation of the acceleration α is large other than the shift, it is determined that the vehicle is traveling on a bad road, and the learning control is interrupted.
Accumulator pressure Pa is prevented from being erroneously corrected.

Although the embodiment of the present invention has been described above, the acceleration may be directly detected by attaching an acceleration sensor.

〔The invention's effect〕

As described above, according to the present invention, in an automatic transmission, a hydraulic shift control system that smoothly controls the rise of a clutch operating oil pressure by an accumulator,
By correcting and controlling the shelf pressure of the clutch operating oil pressure together with the accumulator pressure, the shift feeling can be satisfactorily corrected with respect to individual differences, aging, and the like, and shift shock can be effectively reduced.

Furthermore, since the accumulator pressure is corrected by learning the magnitude and occurrence state of the actual shift shock, the present invention can also be applied to a case where the accumulator pressure is controlled by other factors. Can be optimized.

Furthermore, since the accumulator pressure is corrected by learning the magnitude and occurrence state of the actual shift shock, it can be applied even when the accumulator pressure is controlled by other factors. Can be optimized.

In addition, a shift shock can be determined with high accuracy based on the vehicle body acceleration and the shift time, and the accumulator pressure can be appropriately corrected in relation to the shift time.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a shift shock reducing device for an automatic transmission according to the present invention, FIG. 2 is a diagram of operating hydraulic pressure characteristics of a shift clutch, and FIG. 3 is a characteristic of vehicle speed and acceleration indicating a shift shock state. FIG. 4 is a flowchart of the operation of reducing the shift shock, and FIG. 5 is a diagram illustrating a shift shock reduction state by hydraulic pressure correction. . 1 ... shift clutch, 10 ... accumulator, 11 ... accumulator pressure oil passage, 12 ... accumulator control valve, 13 ... duty solenoid, 20 ... control unit, 24 ... shift shock determination means, 26 ... shift Time calculation means, 28: Accumulator pressure correction amount learning means

Claims (2)

(57) [Claims] An accumulator is connected to an oil passage for operating hydraulic pressure to a transmission clutch, and a duty solenoid for variably controlling an accumulator pressure with an electric signal from at least a control unit is provided in an accumulator pressure oil passage on a back pressure side of the accumulator. A shift shock judging means for judging the magnitude of an actual shift shock based on the vehicle body acceleration, and an accumulator pressure correction learning for correcting an accumulator pressure according to a length of a shift time until a shift shock occurs after a shift is started. And a shift shock reducing device for an automatic transmission. 2. The accumulator pressure correction amount learning means according to claim 1,
The shift shock reduction device for an automatic transmission according to claim 1, wherein the accumulator pressure is corrected to decrease when the shift time is short in a shift shock occurrence state, and to increase the accumulator pressure when the shift time is long.