JP2899760B2 - Line pressure control method for continuously variable transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line pressure control method for a continuously variable transmission, and more particularly to a throttle opening by a control unit that inputs output signals of a throttle sensor and a failure detection timer. The present invention relates to a line pressure control method for a continuously variable transmission that calculates a target value of the line pressure from the target value and controls the line pressure based on the target value.

2. Description of the Related Art In a vehicle, a transmission is interposed between an internal combustion engine and drive wheels. This transmission changes the driving force of the drive wheels and the traveling speed in accordance with the traveling conditions of the vehicle that vary over a wide range, thereby sufficiently exhibiting the performance of the internal combustion engine. The transmission is formed between both pulley parts of a pulley having a fixed pulley part fixed to the rotating shaft and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part. 2. Description of the Related Art There is a continuously variable transmission that changes the radius of rotation of a belt wound around a pulley by increasing or decreasing the width of a groove to transmit power and change a gear ratio (belt ratio). As this continuously variable transmission, for example, JP-A-57-186656,
These are disclosed in JP-A-59-43249, JP-A-59-77159, and JP-A-61-233256.

A line pressure control method for a continuously variable transmission is disclosed in JP-A-64-44341. The line pressure control method of the continuously variable transmission disclosed in this publication detects the actual oil pressure only for a predetermined range when the line pressure and the clutch pressure after shifting from the start mode to the drive mode become equal. A correction amount is calculated from an actual oil pressure signal, a signal of a throttle opening and a previous correction amount by learning control, and when shifting to open-loop control, the target line pressure is corrected and controlled in accordance with the correction amount, and Pressure fluctuation deviation is eliminated.

[Problems to be Solved by the Invention] By the way, in the conventional line pressure control method of the continuously variable transmission, a method of setting a target value in accordance with a throttle opening depressed in a start mode, and running in a drive mode The engine torque is calculated according to the middle throttle opening and the engine speed, and the target value is set according to the engine torque. In both controls, the throttle opening is an important factor in calculating the target value of the line pressure.

In addition, the control unit has a function of detecting an abnormal state of the throttle sensor and each sensor, and when each sensor fails, a fail-safe function is operated to perform appropriate control.

However, the output value from the sensor is input as a normal value from the occurrence of the failure of each sensor until the control unit determines the sensor failure, and the input value controls the line pressure.

Therefore, for example, when the throttle sensor is disconnected and a signal indicating that the throttle opening is zero is output, the control unit sets the target value of the line pressure with the zero output signal as a normal value, and obtains an appropriate line pressure. As a result, clutch slip and belt slip occur, which adversely affects the transmission and degrades ride comfort.

[Object of the Invention] Accordingly, an object of the present invention is to provide a throttle sensor for detecting a throttle opening and a failure detection timer to eliminate the above-mentioned inconvenience, and to provide an output of the throttle sensor and the failure detection timer. A control unit for inputting a signal is provided. The control unit calculates the target value of the line pressure from the throttle opening and stores it as the previous target value, and outputs an abnormal signal of the throttle sensor whose throttle opening is out of the range of the upper and lower limit values. Sometimes, the target value immediately before the start of abnormal signal output is used without updating the target value, and the timer is operated.When the timer has elapsed for a predetermined time, it is determined that the throttle sensor has failed, and the preset value is set. The line pressure is controlled during the period from when the throttle sensor outputs an abnormal signal to when the fail-safe function is activated. Another object of the present invention is to realize a line pressure control method for a continuously variable transmission that can control the engine pressure in a stable manner, reliably prevent the occurrence of clutch slip and belt slip, and secure a stable running feeling.

[Means for Solving the Problems] In order to achieve this object, the present invention relates to a method for fixing a pulley between a fixed pulley and a movable pulley detachably attached to the fixed pulley. In a line pressure control method for a continuously variable transmission, the speed of which is controlled so as to increase or decrease the groove width of the belt wound around the two pulleys to increase or decrease the rotation radius of the belt and change the gear ratio, a throttle sensor for detecting a throttle opening is provided. A failure detection timer that operates only for a predetermined time from when an abnormality signal of the throttle sensor is out of the range of the upper and lower limit values at which the throttle opening is set until the fail-safe function is activated; A control unit for inputting an output signal with the timer for
This control unit calculates a target value of the line pressure from the throttle opening and stores the target value as the previous target value, and does not update the target value when the throttle sensor outputs an abnormal signal of the throttle sensor which is out of the range of the upper and lower limits. The timer uses the target value immediately before the start of the output of the abnormal signal and activates the timer. When the timer has passed a predetermined time, the throttle sensor is determined to be faulty and the line pressure is controlled by a preset value. It is characterized by doing.

[Operation] According to the invention described above, when an abnormal signal is output from the throttle sensor whose throttle opening is out of the range of the upper and lower limits, the target value immediately before the start of the abnormal signal output is used without updating the target value. The timer is operated, and when the timer has elapsed for a predetermined time, it is determined that the throttle sensor is malfunctioning, the line pressure is controlled by a preset value, and the fail-safe function is activated from the time of output of an abnormal signal of the throttle sensor. The line pressure during this period is controlled in a stable manner, clutch slips and belt slips are reliably prevented, and a stable running feeling is ensured.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 4 show an embodiment of the present invention. In FIG. 4, reference numeral 2 denotes a belt-driven continuous variable transmission, 2A denotes a belt, 4 denotes a driving pulley, 6 denotes a driving-side fixed pulley part, 8 denotes a driving-side movable pulley part, and 10 denotes a driven-side pulley. , 12 are driven-side fixed pulley pieces, and 14 is a driven-side movable pulley piece. As shown in FIG. 4, the drive-side pulley 4 is a drive-side fixed pulley piece 6 that is fixed to a rotating shaft 16.
And a drive-side movable pulley piece 8 attached to the rotary shaft 16 so as to be movable and non-rotatable in the axial direction of the rotary shaft 16. The driven pulley 10 also has a driven-side fixed pulley piece 12 and a driven-side movable pulley piece 14, similarly to the drive-side pulley 4.

First and second housings 18 and 20 are mounted on the driving-side movable pulley piece 8 and the driven-side movable pulley piece 14, respectively, to form first and second hydraulic chambers 22 and 24, respectively. . At this time, the second hydraulic chamber 24 on the driven side
There is provided a biasing means 26 comprising a spring or the like for biasing the second housing 20 in the direction of enlargement.

An oil pump 28 is provided on the rotating shaft 16. The oil pump 28 communicates with the first and second hydraulic chambers 22 and 24 via first and second oil passages 30 and 32, respectively. Is provided with a primary pressure control valve 34 as a shift control valve for controlling a primary pressure as an input shaft sheave pressure. Further, the line pressure by the third oil passage 36 to the first oil passage 30 of the oil pump 28 side of the primary pressure control valve 34 (typically 5~25kg / cm ²⁾ to a constant pressure (3-4 kg / cm ²⁾
A first pressure control first three-way solenoid valve 42 is connected to the primary pressure control valve 34 via a fourth oil passage 40 to the primary pressure control valve 34.

In the middle of the second oil passage 32, a line pressure control valve 44 having a relief valve function for controlling a line pressure as a pump pressure is provided.
Through a fifth oil passage 46, and the line pressure control valve
The second oil passage 48 communicates with a second three-way solenoid valve 50 for line pressure control through a sixth oil passage 48.

Further, a clutch pressure control valve 52 for controlling a clutch pressure is communicated with a seventh oil passage 54 in the middle of the second oil passage 32 on the second hydraulic chamber 24 side of the portion where the line pressure control valve 44 communicates. An eighth oil passage 56 communicates with the clutch pressure control valve 52 with a third clutch solenoid valve 58 for clutch pressure control.

The primary pressure control valve 34, the primary pressure control first solenoid valve 42, the constant pressure control valve 38, the sixth oil passage 4
8. The second solenoid valve 50 for line pressure control and the clutch pressure control valve 52 are connected to each other by a ninth oil passage 60.

The clutch pressure control valve 52 is connected to the hydraulic
While communicating with the oil passage 64, a pressure sensor 68 is provided in the middle of the tenth oil passage 64 by an eleventh oil passage 66.
To communicate. The pressure sensor 68 can directly detect the hydraulic pressure when controlling the clutch pressure in the hold and start modes and the like, and contributes when instructing the detected hydraulic pressure to be the target clutch pressure. In the drive mode, the clutch pressure becomes equal to the line pressure, which also contributes to line pressure control.

An input shaft rotation detection gear 70 is provided outside the first housing 18, and a first rotation detector 72 on the input shaft side is provided near an outer peripheral portion of the input shaft rotation detection gear 70. Further, an output shaft rotation detection gear 74 is provided outside the second housing 20, and a second rotation detector 76 on the output shaft side is provided near an outer peripheral portion of the output shaft rotation detection gear 74. Then, detection signals from the first rotation detector 72 and the second rotation detector 76 are output to a control unit 82, which will be described later, to grasp the engine speed and the belt ratio.

The hydraulic starting clutch 62 is provided with an output transmission gear 78, and a third rotation detector 80 for detecting the rotation of the final output shaft is provided near the outer periphery of the gear 78. That is, the third rotation detector 80 detects the rotation of the reduction gear, the differential, the drive shaft, and the final output shaft directly connected to the tire, and can detect the vehicle speed. Further, the second rotation detector 76 and the third
The rotation detector 80 can also detect rotation around the hydraulic start clutch 62, which contributes to the detection of the clutch slip amount.

Further, control for inputting various conditions such as the throttle opening of a carburetor (not shown) of the vehicle and the engine rotation and the vehicle speed from the first to third rotation detectors 72, 76, 80, and changing the duty ratio to perform shift control. A control unit 82 controls opening and closing operations of the first three-way solenoid valve 42 for primary pressure control, the second three-way solenoid valve 50 for line pressure control, and the third three-way solenoid valve 58 for clutch pressure control. In addition, the pressure sensor 68 is configured to be controlled. Also,
The various signals input to the control unit 82 and the function of the input signal will be described in detail. The following signals are required for each range by the range signal such as P, R, N, D, L, etc. Line pressure, ratio, clutch control, carburetor throttle opening detection signal …… Detects engine torque from memory previously input into the program, determines target ratio or target engine speed, carburetor idle position detection signal Accuracy improvement in correction and control of the carburetor throttle opening sensor, accelerator pedal signal …… Detects the driver's will based on the depression of the accelerator pedal, determines the control direction when driving or starting, brake signal …… Brake pedal Detects the presence or absence of stepping motion of the vehicle, determines the control direction such as disengaging the clutch Optional signal …… Sports (or economy) performance of the vehicle
There is an option to use it.

The primary pressure control valve 34 has a spool valve that reciprocates in a body (not shown).

Further, a throttle sensor 83 connected to the control unit 82 and detecting a throttle opening is provided, and the fail-safe function is activated when an abnormal signal of the throttle sensor 83 is out of the range of the upper and lower limit values at which the throttle opening is set. A failure detection timer 84 is provided which operates only for a predetermined time until the failure occurs.

The control unit 82 receives an output signal of the throttle sensor 83 and the failure detection timer 84, and receives a target line pressure PLIN which is a target value of the line pressure from the throttle opening THRT.
SP is calculated and the target line pressure PLINSP is stored as the previous target value, and when the throttle opening is out of the range of the upper and lower limits, the target line pressure PLINSP is not updated and the target line pressure PLINSP is not updated. A configuration in which the target value immediately before the start of output is used and the timer 84 is operated, and when the timer has passed a predetermined time, the throttle sensor is determined to be malfunctioning and the line pressure is controlled by a preset value. Having.

More specifically, a general fault detection measure for the throttle sensor 83 is to digitize the sensor output voltage level by an A / D conversion circuit (not shown) in the control unit 82, and to set a preset upper / lower limit value and digitization. The detected value is compared with the detected value to detect a failure.

Further, the preset value θ is set to the throttle opening degree.
A constant value of about 30 to 60% of THRT.

Further, the target line pressure PLINSP is a normal start mode, a special start mode, a drive mode,
Then, a calculation or a fixed value is set for each mode of the neutral hold coast inhibit.

In the drive mode only, closed control by clutch pressure is performed.

The target line pressure PLINSP is set by a basic calculation loop, for example, every 20 msec.

Furthermore, the calculated target line pressure PLINSP calculated this time is stored as the target line pressure PLINSPL immediately before the start of the output of the abnormal signal, and is set as the next comparison value.

Reference numeral 86 denotes a piston of the hydraulic start clutch 62, 88
Is an annular spring, 90 is a first pressure plate, 92 is a friction plate, 94 is a second pressure plate, 96 is an oil pan, and 98 is an oil filter.

 Next, the operation will be described.

As shown in FIG. 4, the belt-driven continuously variable transmission 2 includes an oil pump 28 located on the rotating shaft 16 and a rotating shaft 16.
The oil is absorbed from an oil pan 96 at the bottom of the transmission via an oil filter 98. The line pressure, which is the pump pressure, is controlled by the line pressure control valve 44.If the amount of leakage from the line pressure control valve 44, that is, the escape amount of the line pressure control valve 44, is large, the line pressure becomes low,
Conversely, if the amount is small, the line pressure increases.

Next, the electronic control of the belt-driven continuously variable transmission 2 will be described.

The continuously variable transmission 2 is hydraulically controlled, and in accordance with a command from the control unit 82, an appropriate line pressure for belt holding and torque transmission, a primary pressure for gear ratio change, and a clutch are securely connected. The clutch pressures for the engagement are secured respectively.

A description will be given along a control flowchart of the belt-driven continuously variable transmission 2 shown in FIG.

The line pressure control program of the belt-driven continuously variable transmission 2 is started by driving the internal combustion engine (not shown) (10
0), and it is determined (102) whether or not the failure of the throttle sensor 83 has been confirmed.

If this determination (102) is YES, a preset value θ of about 30 to 60% is input as the throttle opening THRT (10
4) Then the target line pressure PLINS according to each mode of the next processing
The process proceeds to the determination of P, and also proceeds to the determination of the target line pressure PLINSP according to each mode even when the determination (102) is NO.

That is, in the normal start mode, the value PLCRV (THRT) calculated from the throttle opening THRT is set as the target line pressure PLINSP (106).

In the special start mode, the value g (THRT, RATC) calculated from the throttle opening THRT and the belt ratio RATC is set as the target line pressure PLINSP (10
8).

In the drive mode, the throttle sensor 83
(110) is determined as to whether or not a failure has occurred.
Is YES, the process proceeds to the calculation of the target line pressure PLINSP in the special start mode (108), and the
When 0) is NO, the value f (Te, Te, calculated from the engine torque Te, the belt ratio RATC, the clutch input speed NCi, and the oil temperature TENPS calculated from the map of the throttle opening THRT and the engine speed. RATC, NCi, TEMPS) as the target line pressure PLINSP (112).

Then, in each mode of the neutral hold coast inhibit, a fixed value Km different for each mode is set as the target line pressure PLINSP (114).

After setting the target line pressure PLINSP as described above, it is determined whether the failure detection timer 84 is operating (116).
If the determination (116) is YES, the previous value of the target line pressure PLINSP is used, the failure detection timer 84 proceeds with the failure detection processing of the throttle sensor 83 (118), and the determination (116) is NO.
In the case of, the target line pressure PLINSP is updated (120) to use the target line pressure PLINSP as the current target value.

Then, the target line pressure PLINSP is filtered (122).
Is performed, it is determined whether or not the throttle sensor 83 is out of order (124). If the determination (124) is YES, the process proceeds to an open loop process (126) based on the oil temperature TEMPS, and the determination (124) If 124) is NO, it is determined (128) whether or not the mode is the drive mode.

If the determination (128) is NO, the process proceeds to the open loop process (126) described above, and if the determination (128) is YES, the process proceeds to a closed loop process (130) using the clutch pressure PCLU.

After each of the loop processes (126) and (130), the line pressure control duty is output (132), and the line pressure control program is returned (134).

FIG. 2 is a block diagram showing a control flowchart of the belt-driven continuously variable transmission 2 described above.

That is, in the normal start mode (200), the value PLCRV (THR
T) is set as the target line pressure PLINSP. In the special start mode (202), the value g (THRT, RATC) calculated from the throttle opening THRT and the belt ratio RATC is set as the target line pressure PLINSP, and the drive mode ( 20
In 4), the engine torque Te calculated from the map of the throttle opening THRT and the engine speed and the belt ratio
The value f (Te, RATC, NCi, TEMPS) calculated from the RATC, the clutch input speed NCi, and the oil temperature TENPS is applied to the target line pressure PL.
INSP.

During the operation of the failure detection timer, the target line pressure PLINSPL immediately before the start of the output of the abnormal signal is set as the target line pressure PLINSP.

After the failure is determined, the throttle opening THRT is set to θ which is set in advance, and the calculated value PLCRV (θ) is set to the target line pressure PLINSP.

In each mode (206) of the neutral hold coast inhibit, a fixed value Km different for each mode is set as the target line pressure PLINSP.

Then, select the mode that matches the driving condition of the vehicle (20
8) Then, the target line pressure PLINSP is filtered (210), and the final target line pressure PLINSPF is calculated.

After the filter processing (210), the open loop processing (212) in the control mode and the clutch pressure PCL are performed.
After performing one of the closed loop processing (214) and the duty limit processing (216) for setting the upper and lower limits, the line pressure control duty is output.

Then, as shown in FIG.
A sudden change in the target line pressure PLINSP from the time when the abnormal signal is output at 83 to the time when the failure is determined to activate the fail-safe function is prevented.

By using the target line pressure PLINSPL immediately before the start of the abnormal signal output without updating the target line pressure PLINSP during the period from when the abnormal signal is output from the throttle sensor 83 to when the fail-safe function is activated, The line pressure (speed ratio) immediately before the start of the output of the abnormal signal can be maintained for a predetermined time, the speed ratio can be kept constant, the line pressure can be controlled stably, and a fail-safe function is provided after a predetermined time has elapsed. Works, the shift shock when the control is performed at the preset target line pressure can be suppressed, and the occurrence of clutch slip and belt slip can be surely prevented.

Further, since the occurrence of clutch slip and belt slip can be prevented by the control unit 82, there is no shock at the time of output of an abnormal signal of the throttle sensor 83, and there is no fear of adversely affecting the transmission, and a stable running feeling is secured. Yes, practically advantageous.

Furthermore, in the conventional apparatus having a timer, it is possible to deal with the problem only by changing the program, that is, by changing the software. Therefore, the configuration is not complicated, the cost can be maintained at a low cost, and it is economically advantageous. is there.

[Effect of the Invention] As described in detail above, according to the present invention, a throttle sensor for detecting a throttle opening is provided,
A failure detection timer is provided, and a control unit for inputting output signals of the throttle sensor and the failure detection timer is provided.The control unit calculates a target value of the line pressure from the throttle opening and stores the target value as a previous target value. When an abnormal signal is output from a throttle sensor whose throttle opening is out of the range of the upper and lower limits, the target value is not updated, the target value immediately before the start of the abnormal signal output is used, and the timer is operated. In this case, since the throttle sensor is determined to be faulty and the line pressure is controlled by a preset value, the target value is not updated between the time when the throttle sensor abnormal signal is output and the time when the fail-safe function is activated. The target value immediately before the start of the abnormal signal output is used to maintain the line pressure (speed ratio) immediately before the start of the abnormal signal output for a predetermined time. In addition, the gear ratio can be kept constant, the line pressure can be controlled in a stable manner, the fail-safe function is activated after a lapse of a predetermined time, and the gear shift when the control is performed at a preset target line pressure is performed. Shock can be suppressed, and the occurrence of clutch slip and belt slip can be reliably prevented. Further, since the occurrence of clutch slip and belt slip can be prevented by the control unit, there is no shock at the time of output of an abnormal signal of the throttle sensor, and a stable running feeling can be secured, which is practically advantageous.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a flowchart for controlling a continuously variable transmission driven by a belt, and FIG. 2 explains control of a target line pressure of the continuously variable transmission driven by a belt. FIG. 3 is a block diagram of a belt-driven continuously variable transmission, and FIG. 3 is a block diagram of the belt-driven continuously variable transmission. In the figure, 2 is a belt-driven continuously variable transmission, 2A is a belt, 4 is a driving pulley, 10 is a driven pulley, 30 is a first oil passage, 32 is a second oil passage, and 34 is a primary pressure control valve. , 36 is a third oil passage, 38 is a constant pressure control valve, 40 is a fourth oil passage, 42 is a first three-way solenoid valve, 44 is a line pressure control valve, 46 is a fifth oil passage, 48 is a sixth oil passage, 50 is a second three-way solenoid valve, 52 is a clutch pressure control valve, 54 is a seventh oil passage, 56 is an eighth oil passage, 58 is a third three-way solenoid valve, 60 is a ninth oil passage, 62 is a hydraulic starting clutch, 64 is a tenth oil passage, 66 is an eleventh oil passage, 68 is a pressure sensor, 72 is a first rotation detector, 76 is a second rotation detector, 80 is a third rotation detector, 82 is a control unit, and 83 is a control unit. The throttle sensor 84 is a timer.

Continuation of the front page (72) Inventor Hiroaki Yamamoto 13-1, Sadamotocho, Himeji City, Hyogo Prefecture Mitsubishi Electric Control Software Co., Ltd. Himeji Works (56) References JP-A-62-143742 (JP, A) (58) ) Surveyed field (Int.Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (1)

(57) [Claims] 1. A belt that is wound around a pair of fixed pulleys and a movable pulley that is removably mounted on the fixed pulleys. In a line pressure control method for a continuously variable transmission that performs speed change control so as to increase or decrease a turning radius to change a speed ratio, a throttle sensor that detects a throttle opening is provided, and the throttle opening is set outside an upper and lower limit value range. A failure detection timer that operates only for a predetermined time from when the throttle sensor abnormal signal is output to when the fail-safe function is activated is provided,
A control unit for inputting output signals of the throttle sensor and the failure detection timer is provided. The control unit calculates a target value of the line pressure from the throttle opening and stores the target value as a previous target value. When the abnormal signal is output from the throttle sensor outside the lower limit range, the target value is not updated and the target value immediately before the start of the abnormal signal output is used and the timer is operated. A line pressure control method for a continuously variable transmission, comprising: determining that the throttle sensor has failed; and controlling the line pressure by a preset value.