JPH0657510B2 - Line pressure control device for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a line pressure control device for a belt type continuously variable transmission for a vehicle, and more specifically, a hydraulic control system for operating a line pressure control valve and a shift speed control valve electronically by a duty pressure generated by an electric signal. In the above, the present invention relates to a fail safe at the time of an input failure of the engine speed signal. Regarding this kind of hydraulic shift control, for example, Japanese Patent Laid-Open No.
There is a basic hydraulic control system disclosed in Japanese Patent No. 65755.
This operates to balance the gear ratio control valve by factors of the accelerator depression amount and the engine speed, and determines the gear ratio based on the relationship between the two, and the gear ratio is the control target. Further, in order to obtain the pulley pressing force required for torque transmission, the pressure regulating valve is operated by the factors of the accelerator depression amount and the gear ratio to control the line pressure. By the way, according to the above-mentioned configuration, in the case of the speed change control, the speed of change of the speed change ratio (hereinafter referred to as the speed change speed) is uniquely determined. Hunting and overshoot occur. Further, the characteristics of the line pressure control are uniquely determined, and it is difficult to add various conditions. For this reason, in recent years, in the case of gear shift control or line pressure control, there is a tendency to perform electronic control by taking various states, conditions, and elements into consideration to perform an optimum continuously variable transmission.

[Prior art]

Therefore, in the conventional electronic control of the continuously variable transmission, as shown in, for example, Japanese Patent Application Laid-Open No. 58-88252, a valve is directly operated by using a torque motor, and an engine torque T is set.
And the line pressure P ₁ is controlled by the gear ratio i. In addition, for example, Japanese Patent Laid-Open No. 59-187153 discloses fail-safe in the case of an abnormality of the throttle opening sensor of the engine output sensor.

[Problems to be Solved by the Invention]

By the way, in the line pressure control, as shown in the former case of the prior art, the target line pressure is calculated and controlled by the factors of the engine torque and the gear ratio, but if the input of the engine speed signal fails, the engine torque can be calculated. The latter of the above prior art cannot deal with this. Therefore, in general, in the case of such a trouble, the target line pressure is calculated assuming the maximum engine torque. Therefore, although belt slip due to insufficient line pressure can be prevented, the line pressure becomes higher than an appropriate value, resulting in problems such as pump loss and deterioration of belt durability. The present invention has been made in view of the above circumstances, and a line pressure control device for a continuously variable transmission capable of appropriately calculating a target line pressure and controlling the line pressure when an input failure of an engine speed signal occurs. Is intended to provide.

[Means for solving problems]

In order to achieve the above object, a line pressure control device for a continuously variable transmission according to the present invention includes a drive belt between an input-side primary pulley and an output-side secondary pulley whose pulley groove widths are variably controlled by hydraulic cylinders. Is a continuously variable transmission that winds the engine power to the primary pulley via an electromagnetic clutch, and controls the shift speed output from the control unit to the primary pressure supplied to the hydraulic cylinder of the primary pulley. In the continuously variable transmission that continuously changes the ratio of the winding diameter of the drive belt to the primary pulley and the secondary pulley by changing the speed change valve by a signal, the control unit includes: A gear ratio calculation unit that obtains a gear ratio based on the primary pulley rotation speed and the secondary pulley rotation speed, and An engine torque calculating unit that obtains an engine torque T based on a detection signal from the torque opening and a detection signal from an engine speed, and a target line pressure calculating unit that obtains a target line pressure in the continuously variable transmission based on the gear ratio and the engine torque. And an abnormality detection unit that detects an abnormality in the detection signal of the engine speed and an output signal of the abnormality detection unit that operates to detect the clutch current of the electromagnetic clutch and set the clutch current. A current detection unit for determining whether the clutch is equal to or less than a value or a direct connection state equal to or more than a set value, and when it is determined that the clutch current is in a half-clutch state, the engine torque T _{1 is} calculated from the clutch current by the current detection unit. When the clutch current is directly connected to the half-clutch engine torque calculation unit that obtains No. and the engine torque calculation section of the directly coupled state for obtaining the engine torque T ₂ is provided by a throttle opening signal, wherein the time of output of the abnormality detecting portion, Mu said by the engine torque T ₁ or T ₂ in place of the engine torque T It is characterized in that the line pressure setting control in the gear transmission is performed.

[Action]

In a continuously variable transmission with an electromagnetic clutch, the clutch engagement state can be determined by the clutch current, the engine torque that can be transmitted from the clutch current can be determined in the half-clutch state, and the rotation speed of the primary pulley can be set in the direct coupling state. It is possible to substitute numbers. Focusing on this point, in the control system of the electromagnetic clutch continuously variable transmission, the input state of the engine speed signal is detected, and in the case of an input failure, the clutch engagement state is determined from the clutch current of the electromagnetic clutch. , Calculates the engine torque that can be transmitted from the clutch current in the half-clutch state and the engine torque in the direct-coupled state from the primary pulley rotation speed and the throttle opening, and obtains the target line pressure from the engine torque and the gear ratio to control the line pressure. I am trying. As a result, when the engine speed signal input fails, the clutch torque of the electromagnetic clutch is used to properly determine the engine torque, and the target line pressure determined by the engine torque and the gear ratio is used to control the line pressure as before the failure. Will be done. In this way, according to the present invention, it is possible to set the minimum necessary optimum line pressure even when the engine speed signal is not input.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1, an outline of a transmission system including a continuously variable transmission to which the present invention is applied will be described. An engine 1 is connected to a main shaft 5 of a continuously variable transmission 4 via an electromagnetic clutch 2 and a forward / reverse switching device 3. Link. In the continuously variable transmission 4, the sub shaft 6 is arranged in parallel with the main shaft 5, and the main pulley 5 has the primary pulley 7.
A secondary pulley 8 is provided on the sub shaft 6, each of the pulleys 7 and 8 is equipped with hydraulic cylinders 9 and 10 on the movable side, and a drive belt 11 is wound. Here, the primary cylinder 9 is set to have a larger pressure receiving area, and the primary pressure changes the ratio of the winding diameter of the drive belt 11 to the pulleys 7 and 8 for continuously variable transmission. The auxiliary shaft 6 is connected to an output shaft 13 via a set of reduction gears 12, and the output shaft 13 is configured to be transmitted to a drive wheel 16 via a final gear 14 and a differential gear 15. The electromagnetic clutch 2 operates so as to be engaged or disengaged by the clutch current, and the clutch current Ic changes as shown in FIG. 3 in relation to the engine speed Ne. That is, the clutch current Ic smoothly rises in the half-clutch of the set vehicle speed below the point P, and the direct connection state is maintained by the lock-up current I _L above the point P. Next, the hydraulic control system of the continuously variable transmission 4 will be described. An oil pump 20 driven by the engine 1 is provided, and a line pressure oil passage 21 on the discharge side of the oil pump 20 includes a secondary cylinder 10 and a line pressure control valve. 22 、 Shift speed control valve
The transmission speed control valve 23 communicates with the primary cylinder 9 through the line pressure oil passage 24. Line pressure oil passage 21
Is further communicated with the regulator valve 25, and an oil passage 26 of constant regulator pressure from the regulator valve 25 is connected to the solenoid valve 2
It communicates with one of 7, 28 and the transmission speed control valve 23. Each of the solenoid valves 27, 28 is, for example, turned on and exhausted by a duty signal from the control unit 40 and turned off to output the regulator pressure P _R , and generates such a pulsed control pressure. The pulsed control pressure from the solenoid valve 27 is averaged by the accumulator 30 and acts on the line pressure control valve 22. On the other hand, the pulsed control pressure from the solenoid valve 28 acts on the other side of the shift speed control valve 23 as it is. In the figure, reference numeral 29 is a drain oil passage, 31 is an oil pan, and 32 is an orifice. The line pressure control valve 22 controls the line pressure P _L based on the gear ratio i and the engine torque T by the averaged control pressure from the solenoid valve 27. The speed change control valve 23 has a regulator pressure and a solenoid valve 28.
Due to the relationship of the pulsed control pressure from
It operates in the oil supply position where 1 and 24 are connected and the oil discharge position where the line pressure oil passage 24 is drained. Then, the operation state at the two positions is changed according to the duty ratio to control the flow rate Q of oil supply or oil discharge to the primary cylinder 9, and gear shift control is performed using the gear shift speed di / dt. The electric control system will be described with reference to FIG. First, the shift speed control system will be described. The speed change control system includes a primary pulley 7, a secondary pulley 8, engine speed sensors 41, 42 and 43, and a throttle opening sensor 44. Then, in the control unit, the rotation signals Np and Ns from the two pulley rotation speed sensors 41 and 42 are converted into the actual gear ratio calculation unit.
Input to 45, and obtain the actual gear ratio i by i = Np / Ns. The signal Ns from the secondary pulley rotation speed sensor 42 and the signal θ from the throttle opening sensor 44 are input to the target gear ratio search unit 46. Here, N based on the shift pattern
is is searched from the table of s and θ. Then, the actual gear ratio i of the actual gear ratio calculation unit 45, the steady target gear ratio is of the target gear ratio search unit 46, and the coefficient k of the coefficient setting unit 47 are input to the gear speed calculation unit 48, and di / dt = k The shift speed di / dt is calculated by (is-i), and the downshift or upshift is determined by the positive and negative signs. The signals from the speed change speed calculation unit 48 and the actual speed change ratio calculation unit 45 are further input to the duty ratio search unit 49. Here, a table of the duty ratio D based on di / dt, i is set by the relationship of the duty ratio D = f (di / dt, i), and the duty ratio D is searched from this table. In this table, the value of the duty ratio D is set to be smaller as the gear ratio i becomes smaller and the gear shifts to a higher gear, and as the gear speed di / dt becomes smaller. Then, the signal of the duty ratio D from the duty ratio searching unit 49 is input to the solenoid valve 28 via the driving unit 50. Next, the line pressure control system will be described. The signal θ of the throttle opening sensor 44 and the signal Ne of the engine speed sensor 43 are input to the engine torque calculation unit 51, and the engine torque T is obtained from the table. On the other hand, the actual gear ratio calculation unit
The required line pressure setting unit 52 calculates the required line pressure P _Lu per unit torque based on the actual gear ratio i from 45, and this and the engine torque T of the engine torque calculation unit 51 are input to the target line pressure calculation unit 53. Then, the target line pressure P _L is calculated by P _L = P _Lu · T. The output P _L of the target line pressure calculation unit 53 is input to the duty ratio setting unit 54 to set the duty ratio D corresponding to the target line pressure P _L. And the signal of this duty ratio D is
Input is made to the solenoid valve 27 via the drive unit 55. On the other hand, in the above line pressure control system, as an fail-safe means at the time of input failure of the engine speed signal, the output side of the engine speed sensor 43 has an abnormality detecting section 56 for checking the input signal, and the electromagnetic clutch 2 The clutch current system has a current detector 57. The current detection unit 57 compares the current Ip at the point P in FIG. 3 as a reference, and determines the half-clutch of the current Ip or less and the direct connection state of Ip or more. A spare engine is provided on the output side of the current detection unit 57. It has torque calculation units 58 and 59, and one of the engine torque calculation units 58 can transmit torque T _{1 that} can be transmitted from the clutch current I _L in the half-clutch state.
In the other engine torque calculation 59, the primary pulley speed and throttle opening
The engine torque T ₂ is calculated from the signals of 41 and 44. Then, the engine torque T of each engine torque calculation unit 58, 59
₁ or T ₂ is input to the target line pressure calculation unit 53. Next, the operation of the control device for the continuously variable transmission configured as described above will be described. First, the power corresponding to the depression of the accelerator from the engine 1 is input to the primary pulley 7 of the continuously variable transmission 4 via the clutch 2 and the switching device 3, and the power shifted by the drive belt 11 and the secondary pulley 8 is output. This is the drive wheel 16
It travels by transmitting to the side. During the traveling, the target line pressure is set larger as the engine torque T is larger in the low speed stage where the value of the actual gear ratio i is large, and the duty signal corresponding to this is input to the solenoid valve 27 to generate the control pressure. By operating the line pressure control valve 22 with the averaged pressure, the line pressure P _L of the line pressure oil passage 21 is increased. The line pressure P _L is controlled so as to decrease by the same action as the gear ratio i decreases and the engine torque T decreases, and thus the pulley corresponding to the transmission torque of the drive belt 11 is constantly generated. Apply pressing force. Therefore, the presence or absence of the input of the engine speed signal in the line pressure control will be described. The input state of the engine speed signal is always checked by the abnormality detection unit 56. Then, in the normal case, the preliminary calculation system of the engine torque using the clutch current becomes inoperative, and the engine torque calculation unit 51 causes the engine speed sensor 43 to rotate the engine speed Ne.
Is input to calculate the engine torque T together with the throttle opening θ. On the other hand, if the input of the engine speed signal fails, the abnormality is detected by the abnormality detection unit 56, and the current detection unit 57 is operated by the output signal of the abnormality detection unit 56. Therefore, the current detector 57
Determines whether the clutch current of the electromagnetic clutch 2 is a half clutch with a set value Ip or less, or is in a direct connection state with Ip or more. In the half clutch, the engine torque calculation unit 58 determines a torque T ₁ that can be transmitted from the clutch current Ic. Obtained and input this to the target line pressure calculation unit 53. Thus, using the required line pressure P _Lu per unit torque according to the actual gear ratio i and the transmission torque T ₁ due to the clutch current, the target line pressure P _L is calculated by P _L = P _Lu · T ₁ , and this target line pressure P _L is calculated.
_{At L} , the line pressure is set to match the engine output actually input to the continuously variable transmission 4. On the other hand, in the direct connection state, the engine torque calculation unit 59 calculates the engine torque T ₂ from the primary pulley rotation speed Np from the sensors 41 and 44 and the throttle opening θ, and the target line pressure calculation unit 53 is calculated as described above. To enter. here,
Since the primary pulley rotation speed Np is equal to the engine rotation speed Ne in the clutch direct connection state, the engine torque T ₂ of the calculation unit 59 becomes equal to the engine torque T of the calculation unit 51, whereby the target line pressure P _L is also P _L. = P _Lu · T ₂ = P _Lu · T, and the line pressure is controlled without changing from the case where the engine speed signal is used. Although one embodiment of the present invention has been described above, it is also possible to perform software processing with a microcomputer.

【The invention's effect】

As described above, according to the present invention, when the target line pressure is calculated and the line pressure is controlled by inputting the engine speed signal, etc., the clutch current of the electromagnetic clutch is generated when the engine speed signal input is out of order. Since the clutch engagement state is determined by and the minimum necessary line pressure control is continued, problems due to insufficient or excessive line pressure do not occur. In the half-clutch state, the line pressure is controlled on the basis of the transmission torque of the clutch, which is better than the case where the engine speed is used.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a line pressure control device of the present invention, FIG. 2 is a block diagram showing an electric control system, and FIG. 3 is a clutch current characteristic diagram of an electromagnetic clutch. 2 ... Electromagnetic clutch, 4 ... Continuously variable transmission, 40 ... Control unit, 43 ... Engine speed sensor, 53 ... Target line pressure calculation section, 56 ... Abnormality detection section, 57 ... Current detection Department,
58 …… Semi-clutch engine torque calculator, 59 …… Directly connected engine torque calculator.

Claims (1)

[Claims] 1. A drive belt is wound between an input-side primary pulley and an output-side secondary pulley whose pulley groove widths are variably controlled by hydraulic cylinders, and the engine power is transmitted through an electromagnetic clutch. A continuously variable transmission input to a primary pulley, wherein the primary pressure supplied to the hydraulic cylinder of the primary pulley is changed via a speed change control valve by a speed change control signal output from a control unit. In a continuously variable transmission that continuously changes the ratio of the winding diameter of the drive belt to the secondary pulley to continuously change the speed, the control unit includes a speed change ratio that determines the speed change ratio based on the primary pulley rotation speed and the secondary pulley rotation speed. The calculation unit, the detection signal from the throttle opening and the detection signal from the engine speed Therefore, the engine torque calculation unit that determines the engine torque T and the target line pressure calculation unit that determines the target line pressure in the continuously variable transmission based on the gear ratio and the engine torque are provided, and an abnormality of the detection signal of the engine speed is detected. It operates according to the abnormality detection unit for detecting and the output signal of the abnormality detection unit, detects the clutch current of the electromagnetic clutch, and determines whether the clutch current is a half-clutch state below a set value or a direct connection state above the set value. A clutch current is directly connected to the engine torque calculator of the half-clutch that determines the engine torque T ₁ from the clutch current by the current detector when the clutch current is determined to be in the half-clutch state. It demanded engine torque T ₂ by the primary pulley speed signal and the throttle opening signal when the state An engine torque calculation section of the directly coupled state is provided that, the at the time of output of the abnormality detecting unit, it performs setting control of the line pressure in the continuously variable transmission wherein in place of the engine torque T by the engine torque T ₁ or T ₂ A line pressure control device for a continuously variable transmission characterized by: