JP4668391B2 - Hydraulic control device for automatic transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control device for an automatic transmission that determines hydraulic oscillation when a deviation between a target hydraulic pressure and an actual pressure greatly fluctuates and stops feedback control.
[0002]
[Prior art]
Conventionally, in a belt type continuously variable transmission or a normal multistage automatic transmission known as A / T, the frictional engagement force of a power transmission member such as a transmission belt or a frictional engagement member is necessary and sufficient. The hydraulic pressure for operating them is controlled so that This hydraulic pressure is also called a line pressure, and is used as a source pressure of a hydraulic actuator for pressing members that transmit power to each other.
[0003]
In the hydraulic control device, first, the target hydraulic pressure of the supply hydraulic pressure is determined based on the vehicle state, and the original hydraulic pressure is continuously changed so that the deviation between the actual control hydraulic pressure and the target hydraulic pressure is eliminated. Yes.
[0004]
For example, in a belt-type continuously variable transmission, the groove width between the secondary pulley and the primary pulley is varied in an inversely proportional state to obtain a gear ratio suitable for the driving state. In this case, the secondary hydraulic pressure supplied to the secondary pulley is The primary pressure supplied to the primary pulley is set with the line pressure as the original pressure.
[0005]
The secondary pressure and the primary pressure are variably set according to operating conditions, and feedback control is often used for this shift control. For example, in Japanese Patent Laid-Open No. 6-42619, a signal is output to the fluid pressure device so that the secondary pressure and the primary pressure become a predetermined pressure (target oil pressure), the fluid pressure is regulated, and the actual secondary pressure or primary pressure is adjusted. A technique for performing feedback control so that the pressure follows a target hydraulic pressure is disclosed.
[0006]
[Problems to be solved by the invention]
By the way, for example, when another hydraulic control system is controlled using a common line pressure, a temporary pressure fluctuation in a transient state of the other hydraulic control system may disturb the hydraulic pressure supplied to the automatic transmission side. As it becomes easy to influence.
[0007]
In such a state, if feedback control as disclosed in the above publication is continued, in this feedback control, control is performed so that the actual hydraulic pressure follows the target hydraulic pressure. When the pressure fluctuation of the control system affects as a disturbance, the feedback gain is set in the direction to converge early, but since there is a response delay in the hydraulic control system, the actual control hydraulic pressure fluctuation and this There is a phase shift between the control signal for driving the actuator that controls the hydraulic pressure, and this influence causes hydraulic oscillation (hydraulic pressure fluctuation), which hinders controllability.
[0008]
If this phase shift is set according to the deviation between the target oil pressure and the actual oil pressure, or the oil temperature, the target oil pressure, etc., the program becomes complicated and it takes time and effort to make adjustments and checks in consideration of variations. Therefore, good controllability cannot be obtained.
[0009]
In view of the above circumstances, an object of the present invention is to provide a hydraulic control device for an automatic transmission that can easily detect hydraulic oscillation, suppress the hydraulic oscillation, and obtain good controllability.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a hydraulic control apparatus for an automatic transmission according to the present invention includes a target hydraulic pressure setting unit that sets a target hydraulic pressure, an actual pressure detection unit that detects actual pressure, and a deviation between the target hydraulic pressure and the actual pressure. A feedback control unit that sets a feedback correction amount that causes the actual pressure to follow the target hydraulic pressure, and an actual pressure fluctuation detection unit that determines that the oscillation is hydraulic when a deviation between the target hydraulic pressure and the actual pressure varies greatly. The feedback control unit decreases the feedback correction amount stepwise, and the target hydraulic pressure setting unit increases the target hydraulic pressure when the actual pressure fluctuation detection unit determines that the hydraulic pressure oscillation has occurred.
[0011]
In such a configuration, when the deviation between the target hydraulic pressure and the actual pressure greatly fluctuates, it is determined as hydraulic oscillation, the feedback correction amount is decreased stepwise, and the target hydraulic pressure is increased.
[0012]
In this case, preferably, gradual decrease of the feedback correction amount in the upper Symbol feedback control unit, and performs up to the feedback correction amount reaches zero or minimum value.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a control device for a continuously variable transmission.
[0017]
First, the configuration of the drive system of the continuously variable transmission will be described. Reference numeral 1 in FIG. 1 is a continuously variable transmission mounted on a vehicle, and includes a primary pulley 2, a secondary pulley 3, and a drive belt 4 wound around the primary pulley 2 and the secondary pulley 3. The output of the engine 5 is transmitted from the crankshaft 6 to the primary shaft 2A that supports the primary pulley 2 via the torque converter device 7 and the forward / reverse switching device 8, and the continuously variable transmission 1 performs gear shifting and torque amplification. After being performed, it is output from the secondary shaft 3A that pivotally supports the secondary pulley 3 to the wheels W via the reduction gear train 9 and the differential device D.
[0018]
The primary pulley 2 has a primary fixed sheave 2B fixed to the primary shaft 2A and a primary movable sheave 2C supported so as to be slidable in the axial direction with respect to the primary shaft 2A. The groove width between the primary movable sheave 2C and the primary fixed sheave 2B is adjusted by sliding in the axial direction of the primary shaft 2A.
[0019]
Similarly, the secondary pulley 3 has a secondary fixed sheave 3B fixed to the secondary shaft 3A and a secondary movable sheave 3C supported so as to be slidable in the axial direction with respect to the secondary shaft 3A. As the sheave 3C slides in the axial direction of the secondary shaft 3A, the groove width between the secondary movable sheave 3C and the secondary fixed sheave 3B is adjusted.
[0020]
The groove widths of the pulleys 2 and 3 are set according to the relationship between the primary pressure Pb introduced into the primary cylinder 2D and the line pressure (secondary pressure) Ps introduced into the secondary cylinder 3D.
[0021]
Next, the configuration of the hydraulic control system of the continuously variable transmission 1 will be described. The hydraulic pressure discharged from the oil pump 34 communicating with the oil pan 40 is regulated to a predetermined line pressure Ps by the secondary control valve 50 communicating via the line pressure oil passage 41, and this line pressure Ps is the secondary pressure oil. The secondary pressure is supplied as the secondary pressure (Ps) to the secondary cylinder 3D via the passage 42.
[0022]
Further, the line pressure Ps is guided to the primary control valve 60 through the branch oil passage 43 connected to the line pressure oil passage 41, where the pressure is reduced to a predetermined value to generate the primary pressure Pp. Is supplied to the primary cylinder 2D through the primary pressure oil passage 44.
[0023]
Both control valves 50 and 60 are provided with proportional solenoids 51 and 61, and each control valve 50 and 60 generates a line pressure Ps and a primary pressure Pp according to the operation amount of the proportional solenoids 51 and 61. The proportional solenoids 51 and 61 are controlled by solenoid currents Is and Ip from the control device 70.
[0024]
In the control device 70, the primary rotational speed Np detected by the primary rotational speed sensor, the secondary rotational speed Ns detected by the secondary rotational speed sensor, the throttle opening degree θ detected by the throttle opening sensor, and the engine speed detected by the engine rotational speed sensor. A number Ne and various parameters for detecting an operating condition such as a line pressure (actual pressure) Ps detected by a line pressure sensor 45 interposed in the line pressure oil passage 41 are read, and line pressure control and shift control are performed. Note that the shift control of the continuously variable transmission 1 is described in detail in Japanese Patent Application Laid-Open No. 2000-97321 previously filed by the present applicant, and therefore the description thereof is omitted here. Control will be described.
[0025]
FIG. 2 shows a functional block diagram of line pressure control processed by the control device 70. The function for performing the line pressure control includes a target hydraulic pressure setting unit 11, a proportional solenoid basic control amount setting unit 12, an actual pressure detection unit 13, a feedback control unit 14, an actual pressure fluctuation detection unit 15, and a proportional solenoid drive unit 16. The solenoid current Is output from the proportional solenoid drive unit 16 is output to the proportional solenoid 51 of the secondary control valve 50.
[0026]
The target hydraulic pressure setting unit 11 sets the target line pressure Psb, which is the target hydraulic pressure, based on the following equation. That is, first, the gear ratio i is calculated based on the primary rotational speed Np and the secondary rotational speed Ns.
i = Np / Ns (1)
Next, the engine torque Te is calculated by searching the map with interpolation calculation based on the gear ratio i and the throttle opening θ.
Te = f (i · θ) (2)
Thereafter, the input torque Tin for the continuously variable transmission 1 is calculated from the following equation.
Tin = Te · t−gi (3)
Here, t: torque gain by torque converter, gi: inertial force, and target line pressure Psb are calculated from the following equations.
Psb = Tin · Psu−gs + Pm (4)
[0027]
Here, Psu is the secondary pulley slip limit secondary pressure (required secondary pressure), and is set by table search based on the gear ratio i (Psu = f (i)).
gs: Centrifugal pressure of the secondary cylinder, set by table search based on the secondary rotation speed Ns (gs = f (Ns))
Pm: Margin, set by table search based on gear ratio i (Pm = f (i))
[0028]
The proportional solenoid basic control amount setting unit 12 sets a basic solenoid current Iff for driving the proportional solenoid 51 based on the target line pressure Psb. The actual pressure detector 13 detects the actual line pressure (actual pressure) based on the output signal of the line pressure sensor 45.
[0029]
The feedback control unit 14 performs PI control (proportional integration control) based on a deviation ΔP (ΔP = Psb−Ps) between the target line pressure Psb set by the target hydraulic pressure setting unit 11 and the actual pressure Ps detected by the actual pressure detection unit. Alternatively, the feedback gain (current value) If is set using PID control (proportional integral derivative control) or the like.
[0030]
A solenoid current Is corresponding to a current obtained by adding the feedback gain If set by the feedback control unit 14 to the basic solenoid current Iff set by the proportional solenoid basic control amount setting unit 12 for the proportional solenoid 51 from the proportional solenoid drive unit 16. Is output.
[0031]
On the other hand, the actual pressure fluctuation detecting unit 15 obtains a deviation (hydraulic pressure deviation) ΔPs between the actual pressure Ps detected by the actual pressure detecting unit 13 and the target line pressure Psb set by the target hydraulic pressure setting unit 11, and the hydraulic pressure deviation ΔPs is obtained. The oscillation determination value is compared, and it is determined that the hydraulic oscillation has occurred when the vertical fluctuation exceeding the oscillation determination value is repeated within the set time.
[0032]
When the actual pressure fluctuation detecting unit 15 detects the hydraulic oscillation, the feedback control unit 14 sets the feedback gain If to zero or small, and the target hydraulic pressure setting unit 11 increases the target line pressure Psb by a predetermined amount.
[0033]
The detection of the hydraulic oscillation and the control of the target line pressure Psb and the feedback gain If when the hydraulic oscillation occurs are specifically processed according to the hydraulic oscillation detection routine shown in FIG.
First, in step S1, the absolute value | ΔPs | of the hydraulic pressure deviation ΔPs is compared with an oscillation determination value (for example, 0.5 MPa). If the absolute value | ΔPs | exceeds the oscillation determination value, the process proceeds to step S2. If the absolute value | ΔPs | is within the oscillation determination value, the process jumps to step S7, clears the hydraulic oscillation flag Fp (Fp ← 0), and exits the routine.
[0034]
In step S2, it is checked whether the absolute value | ΔPs | exceeds the oscillation determination value and the time until the absolute value | ΔPs | becomes equal to or less than the oscillation determination value is within a predetermined time. If the predetermined time has elapsed, the process jumps to S7, clears the hydraulic oscillation flag Fp (Fp ← 0), and exits the routine.
[0035]
If it is within the predetermined time, the process proceeds to step S3, where it is checked whether or not the hydraulic pressure deviation ΔPs exceeds the reverse oscillation determination value. If not, the process jumps to step S7 to clear the hydraulic oscillation flag Fp. (Fp ← 0) and exit the routine.
[0036]
On the other hand, when the hydraulic pressure deviation ΔPs exceeds the reverse oscillation determination value, it is determined that hydraulic oscillation has occurred, the process proceeds to step S4, the hydraulic oscillation flag Fp is set (Fp = 1), the process proceeds to step S5, and the target line The pressure Psb is increased by a set amount for each calculation cycle, the feedback control is stopped, and the feedback gain If is decreased by the set amount for each calculation cycle with reference to the latest feedback gain If.
[0037]
Meanwhile, in step S6, the elapsed time is measured, and when the predetermined time has elapsed, the target line pressure Psb and the feedback gain If are fixed, and the process proceeds to step S7, where the hydraulic oscillation flag Fp is cleared (Fp ← 0). , Exit the routine.
[0038]
The time measured in step S6 is a time until the target line pressure Psb is increased from the current pressure by a set value (0.2 MPa in the present embodiment) and the feedback gain If reaches zero or a minimum value. Yes, in this embodiment, it is set to about 1 sec.
[0039]
The value of the hydraulic oscillation flag Fb is read by the target hydraulic pressure setting unit 11 and the feedback control unit 14, and when the hydraulic oscillation flag Fb is set, the feedback control unit 14 stops the feedback control, and the hydraulic pressure flag Fb Is cleared, the feedback control unit 14 resumes the feedback control. At this time, the target hydraulic pressure setting unit 11 and the feedback control unit 14 determine the predetermined values based on the target line pressure Psb and the feedback gain If at that time. Control is performed to return to normal control with a slope of.
[0040]
An example of this control will be described based on the time chart of FIG. For example, as shown in the region A, even when the hydraulic pressure deviation ΔPs once falls below the lower-side oscillation determination value, the next upper limit value has not reached the upper-side oscillation determination value. In this state, it is determined that oscillation has been suppressed, and normal control is continued.
[0041]
On the other hand, as shown in region B, when the hydraulic pressure deviation ΔPs falls below the lower-side oscillation judgment value, reverses within the set time, crosses the lower-side oscillation judgment value again, and reaches the upper-side oscillation judgment value (Time t1), it is determined that hydraulic oscillation has occurred, the hydraulic oscillation flag Fb is set, the feedback gain If is decreased stepwise until reaching zero or a minimum value, and the target line pressure Psb is further reduced to the current pressure. To a predetermined value (for example, 0.2 MPa).
[0042]
In this case, optimum values are obtained from experiments and the like when the feedback gain If and the target line pressure Psb are decreased or increased.
[0043]
As described above, in the present embodiment, when the hydraulic pressure deviation ΔPs becomes equal to or higher than the higher-order oscillation determination value and then becomes lower than the lower-order oscillation determination value within a predetermined time, or the hydraulic pressure deviation ΔPs becomes smaller. If the oscillation determination value becomes lower than or equal to the lower-side oscillation determination value and becomes higher than the upper-side oscillation determination value within a predetermined time, it is determined that hydraulic oscillation has occurred, and the feedback gain becomes zero or a minimum value. Therefore, the hydraulic oscillation promoted by the phase shift between the feedback control and the control signal for driving the actuator that controls the line pressure is alleviated.
[0044]
At this time, the target line pressure Psb is increased from the current pressure by a set value (for example, 0.2 MPa), so that the hydraulic pressure variation compensated by the feedback control immediately before the hydraulic oscillation occurs is reduced. Complemented. That is, if the feedback control is stopped when the hydraulic oscillation is detected, the actual line pressure Ps may not reach the target line pressure Psb that has been held by the feedback control so far, so the target line pressure Psb should be increased in advance. Thus, the shortage of line pressure is compensated and belt slip is prevented.
[0045]
This set value may be a fixed value, but when the oil pressure is stable, such as the average value of the feedback gain during a predetermined time before detecting the hydraulic oscillation, the constant vehicle speed, the constant engine speed, etc. Or a variable value obtained from the hydraulic pressure deviation.
[0046]
The present invention is not limited to the above-described embodiment, and may be employed in a hydraulic system that controls the engagement pressure of a friction transmission member of a normal multistage automatic transmission known as, for example, A / T. Is also possible.
[0047]
【The invention's effect】
As described above, according to the present invention, it is possible to easily detect hydraulic oscillation and to suppress the hydraulic oscillation to obtain excellent controllability.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control device for a continuously variable transmission. FIG. 2 is a functional block diagram showing the configuration of a control system. FIG. 3 is a flowchart showing a hydraulic oscillation detection routine. Time chart [Explanation of symbols]
1 Continuously variable transmission (automatic transmission)
11 Target oil pressure setting unit 13 Actual pressure detection unit 14 Feedback control unit 15 Actual pressure fluctuation detection unit If Feedback gain (feedback correction amount)
ΔP Deviation Ps Actual pressure Psb Target line pressure (target hydraulic pressure)

Claims (2)

A target hydraulic pressure setting unit for setting the target hydraulic pressure;
An actual pressure detector for detecting the actual pressure;
A feedback control unit that sets a feedback correction amount that causes the actual pressure to follow the target oil pressure from a deviation between the target oil pressure and the actual pressure;
An actual pressure fluctuation detection unit that determines hydraulic oscillation when the deviation between the target hydraulic pressure and the actual pressure fluctuates greatly;
The automatic transmission characterized in that the feedback control unit decreases the feedback correction amount stepwise and the target hydraulic pressure setting unit increases the target hydraulic pressure when the actual pressure fluctuation detection unit determines that the hydraulic pressure oscillation occurs. Hydraulic control device. Gradual decrease of the feedback correction amount in the feedback control unit, the hydraulic control device for an automatic transmission according to claim 1, characterized in that to the feedback correction amount reaches zero or minimum value.

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