JPH04140555A - Control device for continuously variable transmission - Google Patents

Abstract

PURPOSE:To set a speed change feedback control gain taking account of the actual speed change state so as to improve controllability and convergence by setting the deviation proportional part, in a control gain, of the deviation between the target value and the actual value using clamping pressure difference. CONSTITUTION:The signals of primary pulley rotating speed Np, secondary pulley rotating speed Ns, acceleration opening theta, secondary oil pressure Ps, primary oil pressure Pp, and the like corresponding to engine operation and the travel state are inputted into a control unit 40, where an actual speed change ratio (i), deviation DELTAN between the target primary pulley rotating speed Npd and the primary pulley rotating speed Np, and clamping force difference DELTAP from the secondary oil pressure Ps and primary oil pressure Pp are computed. When the specified deviation DELTAN is generated at the transient time, the value of the integrated part Ki and differential part Kd of this deviation DELTAN is computed to determine deviation proportional part Kp. Since the deviation proportional part Kp is thus set using the oil pressure ratio between the primary and secondary oil pressure, an appropriate control gain can be set in relation to the delay or the like of the whole continuously variable transmission system.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control device for electronically controlling the speed change, etc. of a belt-type continuously variable transmission for a vehicle, and more specifically, the present invention relates to a control device for electronically controlling the speed change, etc. of a belt-type continuously variable transmission for a vehicle. Regarding gain.

[Conventional technology]

This type of continuously variable transmission has a line pressure control system that sets the secondary oil pressure according to the torque transmitted from the engine, and a shift control system that sets the primary oil pressure necessary to obtain a predetermined gear ratio with respect to the secondary oil pressure. It has

In the shift control system, an optimal target value is set in advance according to the engine operating state and the vehicle running state, and the manipulated variable for feedback control is calculated based on the deviation between this target value and the actual value. In addition, in determining the amount of operation,
The control gain is adjusted in consideration of various circumstances such as characteristics specific to the control system of continuously variable transmissions, characteristics of hydraulic drive, driving feeling, etc., and the responsiveness of shift control and shift speed are optimized. It is measured.

Therefore, regarding a conventional control device for a continuously variable transmission that adjusts the feedback control gain, there is, for example, Japanese Patent Application Laid-Open No. 61-271134. Here, the target shift speed is set in relation to the engine rotational state,
It is shown that the gain in feedback control is set in relation to the target shift speed.

[Problem to be solved by the invention]

By the way, in the prior art described above, the feedback control gain is set in the electronic control system based on the target shift speed that is electrically processed and set.
There are the following problems.

That is, the continuously variable transmission has a structure in which a mechanical transmission section including pulleys and a belt is operated by a hydraulic control system.

Therefore, since it includes delay elements such as the hydraulic control system, and the speed is actually changed based on the hydraulic ratio between the secondary hydraulic pressure and the primary hydraulic pressure, the control gain is controlled by elements set software in the electronic control system, as in the prior art. Even if it is set, it does not match the actual control. Therefore, the controllability and convergence of the entire continuously variable transmission system cannot be sufficiently improved.

The present invention has been made in view of the above, and an object of the present invention is to set a feedback control gain for speed change in consideration of the actual speed change state of the hydraulic control system, thereby improving controllability and improving controllability.
An object of the present invention is to provide a control device for a continuously variable transmission that can effectively improve convergence.

[Means to solve the problem]

In order to achieve the above object, the control device for a continuously variable transmission of the present invention includes a primary pulley and a secondary pulley, which are provided so that the effective diameter of the pulley can be changed by changing the width of the bobbin groove using a hydraulic servo device; A goal of a continuously variable transmission in which a belt is wound between a primary pulley and a secondary pulley, and the boolean ratio is variably controlled by balancing the clamping forces of at least the hydraulic servo device of the primary pulley and the hydraulic servo device of the secondary pulley. In a speed change control system that determines a manipulated variable based on the deviation between a value and an actual value and performs feedback control, there is a deviation calculation means that calculates the deviation between the target value and the actual value, a hydraulic servo device for the secondary pulley, and a hydraulic servo device for the primary pulley. a clamping force difference calculation unit that calculates a clamping force difference of the device; a deviation gain determining unit that sets a deviation proportional amount based on the deviation and the clamping force difference; and a deviation gain determining unit that determines a deviation gain based on the deviation proportional amount and the deviation; and a manipulated variable setting means that adjusts and calculates the actual value of the controlled variable to set the manipulated variable.

[For production]

Based on the above configuration, in the feedback shift control of the continuously variable transmission, the deviation proportional portion in the control gain of the deviation between the target value and the actual value is set by the clamping force difference due to the hydraulic pressure difference between the secondary and primary on the continuously variable transmission side. By being
At the low gear and high gear sides, the shift speed is appropriately controlled taking into account the actual gear shift state. Then, the proportional deviation changes together with the clamping force difference for each gear ratio, making it possible to improve responsiveness and stability.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, an embodiment of the control device for a continuously variable transmission according to the present invention will be described. Reference numeral 1 indicates an engine, and this engine 1 is connected to the continuously variable transmission 5 through a clutch 21 and a forward/reverse switching device 3. Shaft 4° connects to primary pulley 6. In the continuously variable transmission 5, a secondary pulley 7 is arranged parallel to a primary pulley 6, and a belt 8 is hung between both pulleys 6 and 7. The winding of the belt 8 is continuously variable by changing the diameter ratio. It is possible to change gears.

Then, from the secondary pulley 7, the secondary shaft 9.
Gear 10. Differential device 11. Transmission is configured to the wheel 13 side via the axle 12.

In addition, in the hydraulic control system of the continuously variable transmission 5, the line pressure control valve 2
0 communicates with the secondary cylinder 7a via the oil passage 21,
A secondary hydraulic pressure Ps corresponding to the transmitted torque is applied to apply force to the pulley in a manner that does not cause belt slip. The oil passage 21 is connected to the speed change control valve 22. It communicates with the primary cylinder 6a via the oil passage 23, and the secondary hydraulic pressure Ps
A predetermined primary hydraulic pressure Pp acts on the
The gear ratio is controlled to a predetermined speed ratio by shifting from one to the other.

Next, the shift feedback control system will be described.

First, the principle of setting the control gain will be described.

In the control system of a continuously variable transmission, what is directly related to the actual speed change is the required oil pressure ratio ep between the secondary oil pressure Ps and the primary oil pressure Pp, and the required oil pressure ratio ep, the actual gear ratio i, and the transfer torque margin rate a. The relationship is shown in Figure 4. The transmission torque margin ratio a is the ratio between the input torque Tin of the continuously variable transmission and the maximum torque T wax that can be transmitted by the actually acting secondary hydraulic pressure Ps (T + n/T
wax).

From this figure, it can be seen that the required oil pressure ratio ep is small in the low speed gear where the actual gear ratio 1 is large (and the required oil pressure ratio ep becomes larger as the actual gear ratio 1 is smaller in the higher gear gear. Therefore, the secondary oil pressure Ps and the primary oil pressure When the difference from Pp is expressed as the clamping force difference ΔP on the boolean side, the value of the clamping force difference ΔP is large in the low speed gear, and the value of the clamping force difference ΔP gradually decreases in the high speed gear.Thus, the clamping force difference ΔP
The value of is an element that changes according to each speed ratio I in accordance with the actual speed change state, and by using this value to set the control gain, it is possible to appropriately control the speed change.

Here, when considering upshifts in shift control, it is desirable that the shift speed be fast in low gears and slow in high gears. To meet this requirement, the proportional bone Kp of the control gain may be set proportionally to the clamping force difference ΔP. In addition, the downshift is at a high speed and the gear change speed is fast.
It is desirable that the speed is slow on the low speed side. For this purpose, the proportional bone Kp of the control gain may be set in inverse proportion to the reciprocal of the clamping force difference ΔP.

Therefore, if the shift control system is shown taking into account the principle of setting the control gain, it will be as follows.

First, the primary pulley rotation speed sensor 30 on the input side of the continuously variable transmission 5. Secondary pulley rotation speed sensor 31 on the output side. Accelerator opening sensor 32. Line pressure sensor 33
．． It has a transmission torque margin setting means 34 and a primary pressure sensor 35, and these sensor signals are transmitted to the control unit 40.
is input and processed.

The control unit 40 includes a primary pulley rotation speed sensor 3
0. The primary pulley rotation speed Np and the secondary pulley rotation speed Ns of the secondary pulley rotation speed sensor 3I have an actual gear ratio calculating section 41 which manually calculates the actual gear ratio i by calculating the primary pulley rotation speed Np and the secondary pulley rotation speed Ns. Calculated by ratio. This actual gear ratio i and line pressure sensor 3
The secondary oil pressure Ps and transmission torque margin rate a of No. 3 are input to the primary oil pressure setting section 42, and the required oil pressure ratio 1) (P
P/Ps).

The required primary oil pressure Ppt is calculated from the relationship between the transmission torque margin rate a and the secondary oil pressure Ps.

It also has a target primary pulley rotation speed search unit 43 into which the secondary pulley rotation speed Ns and the accelerator opening θ of the accelerator opening sensor 32 are input, and the secondary pulley rotation speed N
The optimum target primary pulley rotation speed Npd is determined from the relationship between S and accelerator opening θ.

The target primary pulley rotation speed Npd and the primary pulley rotation speed Np are input to the deviation calculation section 44, and the deviation ΔN is calculated as follows.
Calculated by ΔN-Npd-Np.

Next, a control system for setting a control gain when performing feedback control based on the deviation ΔN of the primary pulley rotation speed will be described. First, there is a deviation integral calculation unit 45 to which the deviation ΔN is input, and the deviation integral Ki is calculated as Kl−ΔN
Similarly, the deviation differential calculation section 4B calculates the deviation differential bone Kd by Kd - dΔN/dt.

In addition, in order to set the deviation proportional bone, the secondary hydraulic pressure Ps
and the primary hydraulic pressure Pp are input to the clamping force difference calculation unit 5.
0, and the clamping force difference ΔP is calculated by ΔP−Ps−Pp.

The deviation ΔN of the primary pulley rotation speed and the clamping force difference ΔP are input to the deviation gain determining section, and first, an upshift is determined when the value of the deviation ΔN is zero or negative, and a downshift is determined when the value of the deviation ΔN is positive. . Based on the control gain setting principle described above, in upshift, the deviation proportional bone K
p is set as Kp-f(ΔN, ΔP) using the deviation ΔN and the clamping force difference ΔP. Further, in the downshift, the deviation proportional bone Kp is set as Kp-f(ΔN, 1/ΔP) by the reciprocal of the deviation ΔN and the clamping force difference ΔP. The deviation gain G is determined as follows based on the deviation proportional bone Kp and the deviation ΔN thus set.

G-Kp ・ΔN Then, these deviation integral Kj, deviation differential Kd, and deviation gain G are input to the manipulated variable setting section 48 to set the actual gear ratio i.
1 for the required primary oil pressure Ppt according to. Kd,
Multiply by G to determine the operating amount.

This operation amount is configured to be output to the speed change control valve 22 via the drive section 49.

Next, the operation of this embodiment will be described.

First, the power of the engine 1 is input to the primary pulley 6 of the continuously variable transmission 5 via the clutch 21 and the forward/reverse switching device 3. At this time, the line pressure control valve 20 supplies the secondary hydraulic pressure Ps corresponding to the transmission torque to the secondary cylinder 7a, and the speed change control valve 22 guides a predetermined primary hydraulic pressure Pp to the primary cylinder 6a, and the belt 8
into position. Therefore, the engine power is shifted by the primary pulley 6, secondary pulley 7, and belt 8 and output to the secondary shaft 9, and this shifting power is further transmitted to the wheels 13, thereby driving the vehicle.

By the way, during this traveling, the primary pulley rotation speed Np depends on the engine operation and traveling conditions.

Secondary pulley rotation speed Ns, accelerator opening θ.

Signals such as secondary oil pressure Ps and primary oil pressure Pp are input to the control unit 40. Then, the actual gear ratio is 1. The target primary pulley rotation speed Npd and the deviation ΔN of the primary pulley rotation speed are calculated. In addition, the secondary hydraulic pressure P
A clamping force difference ΔP is calculated from s and the primary oil pressure Pp.

Therefore, during steady state when the deviation ΔN is zero, the primary pressure setting section 42 uses the required oil pressure ratio ep to set the actual gear ratio to 1. The control amount of the required primary oil pressure Ppt calculated according to the secondary oil pressure Ps is maintained as it is, and this shift signal is output to the shift control valve 22 to maintain a constant gear ratio.

On the other hand, if a predetermined deviation ΔN occurs during a transient period, this deviation ΔN
The values of the integral KI and the differential Kd of N are calculated. Also,
The flowchart in FIG. 2 is executed, and the deviation proportional bone Kp
is determined.

That is, in step S1, the deviation ΔN and the clamping force difference ΔP are read, and in step S2, a downshift or an upshift is determined based on the sign of the deviation ΔN. In the case of upshift, proceed to step S3, and change the deviation proportional bone Kp to the deviation Δ
N and the clamping force difference ΔP, and step S4
Then, a deviation gain G is calculated from the deviation proportional bone Kp and the deviation ΔN, and the process further proceeds to step S5, where this deviation gain G is output. This deviation gain G is the integral Kl.

It is input to the operation amount setting section 48 together with the differential Kd, and is multiplied by the control amount of the required primary oil pressure Ppt to set the operation amount. Then, the shift signal corresponding to the amount of operation is transmitted to the shift control valve 22.
By increasing the primary oil pressure Pp by outputting an output to the primary pulley rotation speed Npd, the gear shift is controlled to the high speed side so as to follow the target primary pulley rotation speed Npd.

At this time, as the target primary pulley rotation speed Npd changes and the deviation ΔN increases, the control gain Ki increases.

The values of Kd and G become larger, and the shifting speed becomes faster. Further, the clamping force difference ΔP is large at the low speed stage and small at the high speed stage, and the deviation proportional bone Kp is set in proportion to this clamping force difference ΔP. Therefore, when upshifting with a shift line such as Lu in FIG. 3, the values of Δp and KD are large on the side of the maximum shift ratio, so the shift speed becomes faster and responsiveness and acceleration are improved. And the minimum gear ratio IH
As the vehicle moves toward the side, the values of Δp and Kp decrease, and the shifting speed becomes slower, and driving stability becomes more important.

On the other hand, in the case of a downshift, the process proceeds from step S2 to step S6 in the flowchart of FIG.
p is set as the reciprocal of the clamping force difference ΔP. There-C1
When downshifting with a shift line like Ld in Figure 3, on the side of the minimum gear ratio ill], the value of Kp becomes larger due to /ΔP, and the shift speed becomes faster, and especially the kickdown becomes faster. It will be done. And the maximum gear ratio ft
As you move toward the side, the shift speed becomes slower, increasing stability at low speeds.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto. For example, it is possible to apply not only the target primary pulley rotation speed but also the gear ratio, boolean position, etc. as the target value.

〔Effect of the invention〕

As explained above, according to the present invention, in a method in which a control device for a continuously variable transmission performs speed change control by feedback based on the deviation between a target value and an actual value, and adjusts a control gain in this case, Since the deviation proportionality is set using the primary and secondary oil pressure ratios on the transmission side, it is possible to appropriately determine the control gain for delays in the entire system of the continuously variable transmission.

Since the deviation proportional bone is set using changes in the clamping force difference between the secondary and primary of each gear ratio, the gear shifting speed can be optimally controlled on the low and high gear sides, improving both responsiveness and stability.

In an upshift, the shift speed is slowed down in response to a shift to a high speed gear, and in a downshift, the opposite characteristics are set, so the controllability of both-speed control can be optimized.

Since the deviation proportional bone is set by proportionally or inversely proportionally determining the value of the clamping force difference in each shift state, control is facilitated and the upshift and downshift characteristics match, which is preferable.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the drive system, hydraulic control system, and electronic control system of a continuously variable transmission according to an embodiment of the present invention, Fig. 2 is a flowchart of the setting operation of the deviation proportional bone, and Fig. 3 is FIG. 4 is a diagram showing the gear change states of upshift and downshift. FIG. 4 is a diagram showing the relationship among the gear ratio, transmission torque margin ratio, and required oil pressure ratio. 5... Continuously variable transmission, 22... Speed change control valve, 40...
・Control unit, 4I...Actual gear ratio calculation unit, 42...
-Target primary pulley rotation speed search unit, 44...deviation calculation unit, 47...deviation gain determination unit, 48...operation amount setting unit, 50...clamp force difference calculation unit. same

Claims (3)

[Claims] (1) A primary pulley and a secondary pulley are provided so that the effective diameter of the pulley can be changed by changing the pulley groove width using a hydraulic servo device, and a belt is wound between the primary pulley and the secondary pulley, and at least the primary pulley In a continuously variable transmission that variably controls the pulley ratio by balancing the clamping force between the hydraulic servo device of the secondary pulley and the hydraulic servo device of the secondary pulley, a shift is performed in which the operation amount is determined based on the deviation between the target value and the actual value and feedback control is performed. In the control system, a deviation calculation means that calculates the deviation between the target value and the actual value, a clamp force difference calculation unit that calculates the clamp force difference between the hydraulic servo device of the secondary pulley and the hydraulic servo device of the primary pulley, and a device that calculates the difference between the deviation and the clamp. A deviation gain determining means that sets a proportional deviation based on the force difference and determines a deviation gain using the proportional deviation and the deviation, and an operation that adjusts and calculates the control amount of the actual value according to at least the deviation gain and sets the manipulated variable. 1. A control device for a continuously variable transmission, comprising: an amount setting means. (2) Claim (1) characterized in that the clamping force difference is calculated by subtracting the secondary hydraulic pressure supplied to the hydraulic servo device of the secondary pulley and the primary hydraulic pressure supplied to the hydraulic servo device of the primary pulley. A control device for the continuously variable transmission described above. (3) In an upshift, the proportional deviation is set according to the clamping force difference, and in a downshift, the proportional deviation is set according to the reciprocal of the clamping force difference.
) Control device for the continuously variable transmission.