JP2022086810A - Control device for vehicle - Google Patents

Abstract

To provide a slip occurrence detecting device capable of detecting occurrence of a slip in a friction clutch at an early stage.SOLUTION: An absolute value of the difference between a front rotation speed N1 on a drive source side of a friction clutch and a rear rotation speed N2 on a drive wheel side of the friction clutch is obtained, and the absolute value is compared with a threshold in magnitude. Then, when the absolute value is equal to or larger than the threshold, it is determined that a slip occurs in the friction clutch. The threshold is set according to an arithmetic expression including at least one of a first correction term proportional to the front rotation speed N1, a second correction term which is inversely proportional to the front rotation speed N1 and is proportional to a time change rate of the front rotation speed N1, and a third correction term proportional to a square value of the front rotation speed N1.SELECTED DRAWING: Figure 4

Description

The present invention relates to a vehicle control device.

A belt-type continuously variable transmission (CVT) is known as a transmission mounted on a vehicle such as an automobile.

The belt-type continuously variable transmission includes a primary pulley, a secondary pulley, and an endless belt wound around the primary pulley and the secondary pulley. Each pulley of the primary pulley and the secondary pulley is supported by a fixed sheave that is fixedly supported by the rotating shaft and is supported by the rotating shaft so as to be movable in the axial direction and non-relatively rotatable, and faces the fixed sheave with a belt sandwiched between them. It is equipped with a movable sheave. When the power from the engine is input to the rotation shaft of the primary pulley, the power is transmitted from the primary pulley to the belt, and the power is transmitted from the belt to the secondary pulley. Further, the movement of each movable sheave of the primary pulley and the secondary pulley changes the winding diameter of the belt with respect to the primary pulley and the secondary pulley, and the gear ratio (pulley ratio) continuously and steplessly changes.

In vehicles equipped with a belt-type continuously variable transmission, for example, when the vehicle gets over a protrusion such as a speed breaker (speed bump), or when the drive wheels are slipping against the road surface, the grip is regained. Occasionally, belt slippage may occur between the pulley and the belt. That is, if the drive wheels of the vehicle rise from the road surface when overcoming the protrusions, or if the drive wheels slip against the road surface, the rotation speed of the output shaft increases, and then the drive wheels grip against the road surface. Occasionally, the torque input to the drive wheels from the road surface causes a sharp decrease in the number of revolutions of the output shaft, and the sudden decrease may cause the belt to slip against the pulley due to the inner shuttlek.

Therefore, a clutch is provided on the power transmission path between the secondary pulley and the drive wheel, and the target clutch torque capacity, which is the target of the transmission torque capacity (clutch torque capacity) of the clutch, is set to the transmission torque capacity (belt torque capacity) of the belt. It is conceivable to set the value smaller than the target belt torque capacity, which is the target of), to the value obtained by adding the margin to the input torque input to the primary pulley. If the clutch torque capacity is smaller than the belt torque capacity, even if an excessive torque is input to the drive wheels from the road surface, the clutch slips before the belt (clutch fuse), so that the occurrence of belt slip can be prevented. ..

Japanese Unexamined Patent Publication No. 2000-193081

When the clutch slips, it is desirable to increase the clutch pressure, which is the hydraulic pressure supplied to the clutch, to increase the clutch torque capacity and eliminate the clutch slip. When the clutch slips, there is a difference between the number of revolutions on the front side (drive source side) and the number of revolutions on the rear side (drive wheel side) of the clutch, so the absolute value of the difference in the number of revolutions before and after the clutch becomes greater than or equal to the threshold value. Therefore, it is possible to detect the occurrence of clutch slippage due to insufficient clutch torque capacity.

However, when the threshold value for the determination is set without any particular grounds, a sufficient margin is required for the threshold value in order to avoid erroneous determination. Further, when the threshold value is set low, in order to avoid erroneous determination, it is confirmed that the absolute value of the difference between the rotation speeds before and after the clutch is equal to or more than the threshold value for a predetermined time. Therefore, the conventional slip detection lacks responsiveness.

An object of the present invention is to provide a slip generation detecting device capable of detecting the occurrence of slip of a friction clutch at an early stage.

In order to achieve the above object, the slip generation detection device according to the present invention has a configuration in which an endless belt is wound around a primary pulley and a secondary pulley on a power transmission path between a drive source and a drive wheel. Used in vehicles equipped with a friction clutch that engages / disengages to allow / block the transmission of power in the power transmission path in series with the stepless speed change mechanism, and detects the occurrence of friction clutch slippage. In the device, the difference between the front rotation speed on the drive source side of the friction clutch and the rear rotation speed on the drive wheel side of the friction clutch is compared with the threshold value, and the absolute value of the difference is equal to or greater than the threshold value. The first correction term proportional to the setting value, the first correction term proportional to the setting value, and inversely proportional to the setting value, with the slip generation determination means for determining the occurrence of the friction clutch slip and the value based on the front rotation speed or the rear rotation speed as the setting value. , A threshold setting means for setting the threshold according to an arithmetic expression including at least one of a second correction term proportional to the time change rate of the setting value and a third correction term proportional to the square value of the setting value. include.

According to this configuration, the difference between the front rotation speed on the drive source side of the friction clutch and the rear rotation speed on the drive wheel side of the friction clutch is obtained, and the magnitude of the difference and the threshold value is compared. Then, it is determined that the friction clutch slips when the absolute value of the difference between the front rotation speed and the rear rotation speed is equal to or more than the threshold value.

The threshold is the first correction term proportional to the setting value, the first correction term proportional to the setting value, the first correction term proportional to the setting value, and proportional to the time change rate of the setting value, with the value based on the front rotation number or the rear rotation number as the setting value. It is set according to an arithmetic expression including at least one of two correction terms and a third correction term proportional to the squared value of the setting value.

For example, when the value based on the front rotation speed is set as the setting value, the first correction term is due to the play in the rotation direction between the rotating body of the sensor that detects the front rotation speed and the rotating body rotating at the front rotation speed. The second correction term is a term considering the delay of the previous rotation speed with respect to the true value, and the third correction term is a pulse signal output by the sensor that detects the previous rotation speed. It is a term that considers the error of the value obtained by quantizing it with respect to the true value of the interval.

Therefore, by including at least one of the first correction term, the second correction term, and the third correction term in the arithmetic expression for setting the threshold value, the error included in the absolute value of the difference between the front rotation number and the rear rotation number is included. The influence on the judgment can be reduced, and the threshold value can be set to a small value. The smaller the threshold value, the smaller the difference between the front rotation speed and the rear rotation speed due to the slip of the friction clutch can be determined, so that the occurrence of slip of the friction clutch can be detected at an early stage.

As a result, even if the friction clutch slips and is repeatedly re-engaged, the shock due to the re-engagement of the friction clutch is small, so that it is possible to suppress a decrease in the durability of the friction clutch.

According to the present invention, the occurrence of slip of the friction clutch can be detected at an early stage.

It is a skeleton diagram which shows the structure of the drive system of the vehicle which mounts the control device which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the control system of a vehicle. It is a figure which shows an example of the time change of the target clutch torque capacity. It is a block diagram which shows the arithmetic circuit for slip detection.

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

<Vehicle drive system>
FIG. 1 is a skeleton diagram showing the configuration of the drive system of the vehicle 1.

The vehicle 1 is equipped with an engine 2 as a drive source, and adopts, for example, an FR (Front-engine Rear-wheel-drive) layout. The engine 2 is mounted on the front portion of the vehicle 1 in a vertical position in which the crankshaft 3 is vertically oriented with respect to the front-rear direction (hereinafter, simply referred to as "front-rear direction") of the vehicle 1.

The engine 2 is, for example, a 3-cylinder 4-stroke engine, but is not limited to a 3-cylinder 4-stroke engine. That is, the number of cylinders of the engine 2 is not limited to 3 cylinders, and may be 4 cylinders or more, or 2 cylinders or less. Further, the number of strokes of the engine 2 is not limited to 4 strokes, and may be 2 strokes. The engine 2 is provided with an electronic throttle valve for adjusting the amount of intake air into the combustion chamber, an injector (fuel injection device) for injecting fuel into the intake air, an ignition plug for generating an electric discharge in the combustion chamber, and the like. There is. Further, a starter motor for cranking the engine 2 is provided along with the engine 2.

The power of the engine 2 is input to the speed change unit 4. The power output from the speed change unit 4 is transmitted to the differential gear 6 via the propeller shaft 5, and is transmitted from the differential gear 6 to the left and right drive wheels (rear wheels) 7L and 7R.

The speed change unit 4 includes a torque converter 8 and a continuously variable transmission (CVT) 9 in a unit case forming an outer shell.

The torque converter 8 is a torque converter with a lock-up mechanism, and includes a front cover 11, a pump impeller 12, a turbine runner 13, and a lock-up clutch (lock-up piston) 14.

The front cover 11 extends in a substantially disk shape around a rotation axis extending in the front-rear direction, and has a shape in which the outer peripheral end thereof is bent toward the rear side opposite to the engine 2 side. The crankshaft 3 of the engine 2 is coupled to the central portion of the front cover 11 so as not to rotate relative to each other.

The pump impeller 12 is arranged behind the front cover 11. The outer peripheral end of the pump impeller 12 is connected to the outer peripheral end of the front cover 11, and the pump impeller 12 is provided so as to be rotatable integrally with the front cover 11.

The turbine runner 13 is arranged between the front cover 11 and the pump impeller 12.

The lockup clutch 14 is located between the front cover 11 and the turbine runner 13. When the hydraulic pressure of the engagement side oil chamber 15 on the turbine runner 13 side is higher than the hydraulic pressure of the release side oil chamber 16 on the front cover 11 side with respect to the lockup clutch 14, the lockup clutch 14 is front-covered by the differential pressure. Moving to the 11 side, the lockup clutch 14 is pressed against the front cover 11, and the pump impeller 12 and the turbine runner 13 are directly connected (lockup on).

On the contrary, when the hydraulic pressure of the release side oil chamber 16 is higher than the hydraulic pressure of the engaging side oil chamber 15, the lockup clutch 14 moves to the turbine runner 13 side due to the differential pressure. When the lockup clutch 14 is separated from the front cover 11, the direct connection between the pump impeller 12 and the turbine runner 13 is released (lockup off). When the pump impeller 12 is rotated by the engine torque in the lock-up-off state, an oil flow from the pump impeller 12 to the turbine runner 13 is generated. This flow of oil is received by the turbine runner 13, and the turbine runner 13 rotates. At this time, the amplification action of the torque converter 8 occurs, and a torque larger than the engine torque is generated in the turbine runner 13.

The continuously variable transmission 9 includes an input shaft 21, a continuously variable transmission mechanism 22, a reverse transmission mechanism 23, and an output shaft 24. The continuously variable transmission 9 is provided so that the input shaft 21 extends in the front-rear direction in the vertical direction.

The input shaft 21 extends on the rotation axis of the torque converter 8 and is rotatably provided integrally with the turbine runner 13 of the torque converter 8. An input shaft gear 25 is integrally formed with the input shaft 21, or an input shaft gear 25 formed separately is supported so as not to rotate relative to each other.

The continuously variable transmission mechanism 22 was wound around the primary shaft 31, the secondary shaft 32, the primary pulley 33 supported by the primary shaft 31, the secondary pulley 34 supported by the secondary shaft 32, and the primary pulley 33 and the secondary pulley 34. It is equipped with a belt 35.

The primary shaft 31 is arranged at a position where its axis is separated from the axis of the input shaft 21 to the lower right when viewed from the rear side, and extends in parallel with the input shaft 21. The secondary shaft 32 is arranged at a position where its axis is separated from the axis of the input shaft 21 toward the upper left when viewed from the rear side, and extends in parallel with the input shaft 21. In this way, the primary shaft 31 and the secondary shaft 32 are separately arranged on the left and right sides with respect to the input shaft 21. As a result, the distance between the primary shaft 31 and the secondary shaft 32 in the vertical direction can be shortened, and the size of the continuously variable transmission 9 in the vertical direction can be reduced. Therefore, even if the vehicle 1 is a vehicle such as a commercial vehicle having a low floor, it is possible to mount the speed change unit 4 on the vehicle 1 while ensuring the minimum ground clearance of the vehicle 1. ..

The primary pulley 33 is arranged to face the primary fixed sheave 41 fixed to the primary shaft 31 with the belt 35 interposed therebetween, and is supported by the primary shaft 31 so as to be movable in the axial direction and non-rotatably relative to the primary shaft 31. It is equipped with a primary movable sheave 42. The primary movable sheave 42 is arranged on the front side with respect to the primary fixed sheave 41.

A cylinder 43 is provided on the side opposite to the primary fixed sheave 41 side, that is, on the front side with respect to the primary movable sheave 42. The inner peripheral end of the cylinder 43 is fixed to the primary shaft 31, extends in the axial direction from the primary shaft 31, and the outer peripheral end portion bends and extends to the rear side. The outer peripheral end of the primary movable sheave 42 is in liquidtight contact with the outer peripheral end of the cylinder 43 from the inside in the radial direction of rotation. The space between the primary movable sheave 42 and the cylinder 43 is formed as an oil chamber (piston chamber) 44.

The secondary pulley 34 is arranged to face the secondary fixed sheave 45 fixed to the secondary shaft 32 with the belt 35 sandwiched between the secondary fixed sheave 45, and is supported by the secondary shaft 32 so as to be movable in the axial direction and non-relatively rotatable. It is equipped with a secondary movable sheave 46. The secondary movable sheave 46 is arranged on the rear side with respect to the secondary fixed sheave 45, and the positional relationship between the secondary fixed sheave 45 and the secondary movable sheave 46 in the front-rear direction is the primary fixed sheave 41 of the primary pulley 33 and the primary. The positional relationship with the movable sheave 42 is reversed.

A piston 47 is provided on the side opposite to the secondary fixed sheave 45, that is, on the rear side with respect to the secondary movable sheave 46. The inner peripheral end of the piston 47 is fixed to the secondary shaft 32 and extends in the axial direction from the secondary shaft 32. The outer peripheral end of the secondary movable sheave 46 extends to the rear side, and the outer peripheral end of the piston 47 is in liquidtight contact with the outer peripheral end of the secondary movable sheave 46 from the inside in the radial direction of rotation. An oil chamber 48 is formed between the secondary movable sheave 46 and the piston 47.

In the continuously variable transmission mechanism 22, the hydraulic pressure supplied to the oil chambers 44 and 48 of the primary pulley 33 and the secondary pulley 34 is controlled, and the groove widths of the primary pulley 33 and the secondary pulley 34 are changed to change the belt. The gear ratio (the pulley ratio between the primary pulley 33 and the secondary pulley 34) is continuously and steplessly changed within a certain gear ratio range.

Specifically, when the belt gear ratio is reduced, the hydraulic pressure supplied to the oil chamber 44 of the primary pulley 33 is increased. As a result, the primary movable sheave 42 of the primary pulley 33 moves to the primary fixed sheave 41 side, and the distance (groove width) between the primary fixed sheave 41 and the primary movable sheave 42 becomes smaller. Along with this, the winding diameter of the belt 35 with respect to the primary pulley 33 becomes large, and the distance (groove width) between the secondary fixed sheave 45 and the secondary movable sheave 46 of the secondary pulley 34 becomes large. As a result, the belt gear ratio becomes smaller.

When the belt gear ratio is increased, the hydraulic pressure supplied to the oil chamber 44 of the primary pulley 33 is lowered. As a result, the thrust of the secondary pulley 34 with respect to the belt 35 becomes larger than the thrust of the primary pulley 33 with respect to the belt 35, the distance between the secondary fixed sheave 45 and the secondary movable sheave 46 of the secondary pulley 34 becomes smaller, and the primary fixed sheave 41 The distance between the and the primary movable sheave 42 becomes large. As a result, the belt gear ratio becomes large.

Although not shown, a bias spring is provided in the oil chamber 48 of the secondary pulley 34. One end of the bias spring is elastically in contact with the secondary movable sheave 46, and the other end is elastically in contact with the piston 47. The elastic force of the bias spring urges the secondary movable sheave 46 and the piston 47 in a direction in which they are separated from each other. The secondary movable sheave 46 is subjected to the hydraulic pressure in the oil chamber 48 and the urging force by the bias spring, and the belt 35 is subjected to the corresponding pinching pressure.

A primary input gear 51 is supported so as to be relatively rotatable at the front end of the primary shaft 31.

A forward clutch 52 is provided between the primary input gear 51 and the primary pulley 33 arranged on the rear side thereof. The forward clutch 52 is a hydraulic friction clutch that is hydraulically engaged and prohibits rotation of the primary input gear 51 with respect to the primary shaft 31. Therefore, in the engaged state of the forward clutch 52, when the primary input gear 51 rotates, the primary shaft 31 rotates integrally with the primary input gear 51. When the hydraulic pressure is released from the forward clutch 52 in this engaged state, the forward clutch 52 is released. By releasing the forward clutch 52, the rotation of the primary input gear 51 with respect to the primary shaft 31 is allowed, and even if the primary input gear 51 rotates, the rotation is not transmitted to the primary shaft 31.

A secondary input gear 53 is supported on the front end of the secondary shaft 32 so as to be relatively rotatable.

A reverse clutch 54 is provided between the secondary input gear 53 and the secondary pulley 34 arranged on the rear side thereof. The reverse clutch 54 is a hydraulic friction clutch that is hydraulically engaged and prohibits rotation of the secondary input gear 53 with respect to the secondary shaft 32. Therefore, when the secondary input gear 53 rotates, the secondary shaft 32 rotates integrally with the secondary input gear 53. When the hydraulic pressure is released from the reverse clutch 54 in this engaged state, the reverse clutch 54 is released. By releasing the reverse clutch 54, the rotation of the secondary input gear 53 with respect to the secondary shaft 32 is allowed, and even if the secondary input gear 53 rotates, the rotation is not transmitted to the secondary shaft 32.

The reverse transmission mechanism 23 is a mechanism that transmits the power (rotation) of the input shaft 21 to the secondary shaft 32 without passing through the stepless speed change mechanism 22. The reverse transmission mechanism 23 includes a reverse idler shaft 55, a first reverse gear 56, and a second reverse gear 57.

The reverse idler shaft 55 extends in the front-rear direction parallel to the input shaft 21.

The first reverse gear 56 is formed integrally with the reverse idler shaft 55, or is formed separately from the reverse idler shaft 55, and is supported by the reverse idler shaft 55 so as not to rotate relative to each other.

The output shaft 24 is arranged on the same axis as the input shaft 21 with a space behind the input shaft 21. The output shaft gear 58 is integrally formed with the output shaft 24, or the output shaft gear 58 formed separately from the output shaft 24 is supported so as not to rotate relative to each other. Correspondingly, the secondary output gear 59 is supported on the secondary shaft 32 adjacent to the rear side of the piston 47 of the secondary pulley 34 by spline fitting so as not to rotate relative to each other. The output shaft gear 58 and the secondary output gear 59 are in mesh with each other.

When the shift lever is in the D position, the forward clutch 52 is engaged and the reverse clutch 54 is released to form the D range. At this time, the power input from the engine 2 to the input shaft 21 via the torque converter 8 is transmitted from the input shaft gear 25 to the primary shaft 31 via the primary input gear 51 by the engagement of the forward clutch 52. On the other hand, even if the power input to the input shaft 21 is transmitted from the input shaft gear 25 to the secondary input gear 53 and the secondary input gear 53 rotates, the secondary input gear 53 becomes the secondary shaft 32 due to the release of the reverse clutch 54. The power is not transmitted to the secondary shaft 32.

When the vehicle 1 travels forward, the forward clutch 52 is engaged and the reverse clutch 54 is released. The power input from the engine 2 to the input shaft 21 via the torque converter 8 is transmitted from the input shaft gear 25 to the primary shaft 31 via the primary input gear 51 by the engagement of the forward clutch 52. On the other hand, even if the power input to the input shaft 21 is transmitted from the input shaft gear 25 to the secondary input gear 53 and the secondary input gear 53 rotates, the secondary input gear 53 becomes the secondary shaft 32 due to the release of the reverse clutch 54. The power is not transmitted to the secondary shaft 32.

The power transmitted to the primary shaft 31 is changed at a belt gear ratio corresponding to the pulley ratio between the primary pulley 33 and the secondary pulley 34, and is transmitted to the secondary shaft 32. Then, the power transmitted to the secondary shaft 32 is transmitted from the secondary output gear 59 to the output shaft 24 via the output shaft gear 58, and is transmitted from the output shaft 24 to the propeller shaft 5.

When the vehicle 1 travels backward, the forward clutch 52 is released and the reverse clutch 54 is engaged. The power input from the engine 2 to the input shaft 21 via the torque converter 8 is transmitted from the input shaft gear 25 to the secondary shaft 32 via the reverse transmission mechanism 23 and the secondary input gear 53 by the engagement of the reverse clutch 54. To. At this time, the secondary shaft 32 rotates in the direction opposite to that when the vehicle 1 moves forward. On the other hand, even if the power input to the input shaft 21 is transmitted from the input shaft gear 25 to the primary input gear 51 and the primary input gear 51 rotates, the forward clutch 52 is released so that the primary input gear 51 becomes the primary shaft 31. The power is not transmitted to the primary shaft 31.

The power transmitted to the secondary shaft 32 is transmitted from the secondary output gear 59 to the output shaft 24 via the output shaft gear 58, and is transmitted from the output shaft 24 to the propeller shaft 5.

<Vehicle control system>
FIG. 2 is a block diagram showing the configuration of the control system of the vehicle 1.

The vehicle 1 is equipped with a plurality of ECUs (Electronic Control Units). Each ECU includes a microcomputer (microcontroller unit), and the microcomputer has, for example, a non-volatile memory such as a CPU and a flash memory and a volatile memory such as a DRAM (Dynamic Random Access Memory). The plurality of ECUs are connected so as to be capable of bidirectional communication by a CAN (Controller Area Network) communication protocol. Various sensors required for control are connected to each ECU, and the detection signals of the connected sensors are input. In addition to the detection signals input from various sensors, information necessary for control is input to each ECU from other ECUs.

FIG. 1 shows an ECU 61 for controlling an engine 2 and a speed change unit 4 among a plurality of ECUs, and as sensors connected to the ECU 61, an engine rotation speed sensor 62, an accelerator sensor 63, and a front rotation speed sensor are shown. 64 and the rear rotation speed sensor 65 are shown.

The engine rotation speed sensor 62 outputs a pulse signal synchronized with the rotation of the engine 2 (rotation of the crankshaft 3) as a detection signal. In the ECU 61, the frequency of the pulse signal input from the engine rotation speed sensor 62 is obtained, and the frequency is converted into the rotation speed (engine rotation speed) of the engine 2.

The accelerator sensor 63 outputs a detection signal according to the amount of operation of the accelerator pedal (not shown) operated by the driver. In the ECU 61, from the detection signal of the accelerator sensor 63, the ratio of the operation amount to the maximum operation amount of the accelerator pedal, that is, 0% when the accelerator pedal is not depressed, and 100% when the accelerator pedal is fully depressed. The accelerator opening, which is a percentage of the speed, is obtained.

The front rotation speed sensor 64 outputs a pulse signal synchronized with the rotation of the primary input gear 51 on the input side of the forward clutch 52 as a detection signal. In the ECU 61, the frequency of the pulse signal input from the front rotation speed sensor 64 is obtained, and the frequency is converted into the front rotation speed N1 which is the rotation speed of the primary input gear 51.

The rear rotation speed sensor 65 outputs a pulse signal synchronized with the rotation of the primary shaft 31 on the output side of the forward clutch 52 as a detection signal. In the ECU 61, the frequency of the pulse signal input from the rear rotation speed sensor 65 is obtained, and the frequency is converted into the rear rotation speed N2 which is the rotation speed of the primary shaft 31.

<Margin setting process>
FIG. 3 is a diagram showing an example of a time change of the target clutch torque capacity.

In the vehicle 1, the transmission torque capacity of the belt 35 of the stepless speed change mechanism 22 with respect to the input torque input to the primary shaft 31 of the stepless speed change mechanism 22 by the ECU 61 during forward travel in which the forward clutch 52 is engaged. The target belt torque capacity, which is the target of (clutch torque capacity), and the target clutch torque capacity, which is the target of the transmission torque capacity (belt torque capacity) of the forward clutch 52, are repeatedly set.

The target belt torque capacity is set to a value larger than the input torque so that the belt 35 does not slip due to the input torque. When the target belt torque capacity is set, the hydraulic pressure supplied to the oil chamber 48 of the secondary pulley 34 of the continuously variable transmission mechanism 22 is controlled by the ECU 61 so that the belt torque capacity matches the target belt torque capacity.

The target clutch torque capacity is set to a value obtained by adding a margin to the input torque, and by managing the margin, the target is such that the clutch torque capacity of the forward clutch 52 does not exceed the belt torque capacity of the stepless speed change mechanism 22. It is set to a value smaller than the clutch torque capacity. When the target clutch torque capacity is set, the ECU 61 controls the clutch pressure, which is the hydraulic pressure supplied to the forward clutch 52, so that the clutch torque capacity matches the target clutch torque capacity.

Hereinafter, the method of setting the margin allowance will be described assuming that the input torque and the target belt torque capacity are constant.

The margin set by the following method may be stored in the non-volatile memory of the ECU 61 or may be stored in the volatile memory of the ECU 61. When the margin allowance is stored in the non-volatile memory, even after the ignition switch of the vehicle 1 is turned off, the margin allowance remains in the memory, so that the ignition switch is turned on next and the vehicle 1 starts traveling forward. At that time, the margin stored in the non-volatile memory may be used for setting the target clutch torque capacity. On the other hand, when the margin is stored in the volatile memory, when the ignition switch is turned off, the memory of the margin is erased, so that the ignition switch is turned on next and the vehicle 1 starts traveling forward. When doing so, it is preferable that the initial value of the margin allowance is used to set the target clutch torque capacity.

If none of the following prohibition conditions 1 to 7 is satisfied while the vehicle 1 is traveling forward, the margin margin is gradually reduced with the passage of time (time T1-T2). The margin allowance may be continuously lowered at a constant rate of change, or may be gradually lowered by a fixed amount.

Prohibition conditions:
1. 1. The front rotation speed N1 and the rear rotation speed N2 are 0 or less than the minimum detectable rotation speed.
2. 2. The lower limit guard of the clutch pressure is operating.
3. 3. Lockup on / off transition.
4. The continuously variable transmission mechanism 22 is in the process of sudden shifting (the time change rate of the gear ratio is constant or higher).
5. Vehicle 1 is suddenly decelerating (deceleration is above a certain level).
6. The input torque is suddenly changing (the time change rate of the input torque is above a certain level).
7. The engine 2 is in a fuel-cut or low-speed state (engine speed is below a certain level).

The prohibition condition 1 is provided to prevent the slip detection of the forward clutch 52 from being delayed. Prohibition conditions 2 to 5 are provided to prevent erroneous determination of insufficient clutch torque capacity. The prohibition condition 6 is provided to prevent the occurrence of slip due to the response delay of the forward clutch 52. The prohibition condition 7 is provided to prevent the engine 2 from stalling. Slip detection and determination of insufficient clutch torque capacity will be described later.

The lower limit guard of the clutch pressure is set to prevent the clutch pressure from dropping below a certain level. The lower limit guard is, for example, the moment when the piston of the forward clutch 52 presses the clutch plate against the clutch disc against the elastic force of the cushioning spring and the gap between the clutch plate and the clutch disc is crushed. It is set to hydraulic pressure. As a result, when slip occurs in the forward clutch 52, the hydraulic pressure supplied to the forward clutch 52 can be increased to promptly stop the slip of the forward clutch 52.

As the margin allowance gradually decreases, the target clutch torque capacity gradually decreases, and the clutch torque capacity (actual clutch torque capacity) of the forward clutch 52 gradually decreases. When the clutch torque capacity gradually decreases and the clutch torque capacity becomes insufficient, the forward clutch 52 slips. When the forward clutch 52 slips, the front rotation speed N1 which is the rotation speed of the primary input gear 51 which is the input side of the forward clutch 52 and the rear rotation speed which is the rotation speed of the primary shaft 31 which is the output side of the forward clutch 52. There is a difference from the number N2. In the ECU 61, when the difference between the front rotation speed N1 and the rear rotation speed N2 becomes equal to or more than a predetermined threshold value, it is determined that the clutch torque capacity is insufficient because the occurrence of slip of the forward clutch 52 is detected. ..

When the clutch torque capacity becomes insufficient (time T2), a value obtained by adding a predetermined value to the margin allowance at that time is set as a new margin allowance. Then, the target clutch torque capacity is raised from the current value to a value obtained by adding a new margin to the input torque (time T2-T3). At this time, the target clutch torque capacity may be continuously increased at a constant rate of change, or may be gradually increased by a fixed amount.

A predetermined value may be added to the value of the margin margin itself when the clutch torque capacity is insufficient, but the margin margin when the clutch torque capacity is insufficient and the margin allowance set in the past. May be weighted and a predetermined value may be added to the value obtained by adding those values.

When a new allowance is set, the new allowance is maintained for a predetermined period (interval) after the shortage of the clutch torque capacity is resolved by raising the target clutch torque capacity (time). T3-T4). The predetermined period is variably set according to various situations. For example, when the margin allowance is larger than the predetermined value, the predetermined period may be set to a shorter period than when the margin allowance is smaller than the predetermined value. The predetermined period may be set by time or by mileage. When set by time, the time when the vehicle 1 is stopped may be excluded from the predetermined period.

If the clutch torque capacity is insufficient during the predetermined period in which the margin is held and the occurrence of slip of the forward clutch 52 is detected, the value obtained by adding the predetermined value to the margin at that time is newly added. It is set as a margin. In this case, it is preferable that the predetermined value is set to a value smaller than the predetermined value when the clutch torque capacity is insufficient due to the gradual decrease of the margin allowance. As a result, it is possible to prevent the clutch torque capacity from being unnecessarily increased.

In addition to that, the predetermined value may be variably set according to the state of the engine 2 (driving state, engine braking state) and the like.

After the lapse of the predetermined period, the margin allowance is gradually reduced (time T4-T5), and the above-mentioned processing is performed again.

<Slip detection>
FIG. 4 is a block diagram showing an arithmetic circuit for slip detection.

In the ECU 61, in order to detect the occurrence of slip of the forward clutch 52, the front rotation speed N1 which is the rotation speed of the primary input gear 51 which is the input side of the forward clutch 52 and the primary shaft 31 which is the output side of the forward clutch 52 The rear rotation speed N2, which is the rotation speed, is acquired.

By multiplying the previous rotation speed N1 by the coefficient α, the first correction term proportional to the previous rotation speed N1 can be obtained. Since there is play in the rotation direction between the rotating body having the detection teeth for generating the pulse signal of the front rotation speed sensor 64 and the primary input gear 51, the first correction term is a term considering the error due to the play. Is set as.

Further, by multiplying the differential value DN1 of the previous rotation speed N1 by the coefficient β and dividing the multiplication value by the previous rotation speed N1, it is inversely proportional to the previous rotation speed N1 and proportional to the time change rate of the previous rotation speed N1. The second correction term is obtained. The second correction term is set as a term in consideration of the fact that the front rotation speed N1 acquired from the detection signal of the front rotation speed sensor 64 is delayed with respect to the true value.

Further, by multiplying the squared value of the previous rotation speed N1 by the coefficient γ, a third correction term proportional to the squared value of the previous rotation speed N1 is obtained. When the previous rotation speed N1 is doubled, the error rate of the value obtained by quantizing the true value of the pulse signal interval output by the previous rotation speed sensor 64 is doubled. It is set as a term considering the error. Since the error of the front rotation speed N1 is a value obtained by multiplying the true value by the error rate, it is appropriate to use the square value of the front rotation speed N1.

Then, the threshold value for slip detection is set by adding the first correction term, the second correction term, and the third correction term.

That is, the slip detection threshold is set according to the following arithmetic expression.
Threshold = α ・ N1 + β ・ DN1 / N1 + γN1 ²

On the other hand, the absolute value of the difference between the front rotation speed N1 and the rear rotation speed N2 is obtained.

After that, the magnitude of the absolute value of the difference between the front rotation speed N1 and the rear rotation speed N2 and the threshold value is compared, and if the absolute value of the difference between the front rotation speed N1 and the rear rotation speed N2 is equal to or more than the threshold value, the vehicle advances. Assuming that the occurrence of slip of the clutch 52 is detected, it is determined that the clutch torque capacity is insufficient.

<Action effect>
As described above, the target clutch torque capacity is set to a value obtained by adding the margin to the input torque, and the clutch pressure of the forward clutch 52 is controlled so that the clutch torque capacity of the forward clutch 52 becomes the target clutch torque capacity. ..

With the forward clutch 52 engaged, the margin is gradually reduced. When the target clutch torque capacity gradually decreases with the gradual decrease of the margin allowance, the clutch torque capacity becomes insufficient, and the occurrence of slip of the forward clutch 52 is detected, a predetermined value is set to the value based on the margin allowance at that time. The added value is set as a new margin.

Since the value obtained by adding the margin margin at the time of detecting the occurrence of slip of the forward clutch 52 to the input torque is the clutch torque capacity required for the forward clutch 52, it is a predetermined value to be added to the value based on the margin margin at the time of shortage. The value can be set to a small value. As a result, the margin allowance can be accurately managed so that the clutch torque capacity is not insufficient and the clutch torque capacity does not exceed the belt torque capacity of the continuously variable transmission mechanism 22. As a result, even if an excessive torque is input to the drive wheels 7L and 7R of the vehicle 1 from the road surface, the forward clutch 52 can be slid before the belt 35, and the operation of this clutch fuse causes belt slip. Can be prevented.

Moreover, since the target clutch torque capacity can be set to a value as small as possible, the target belt torque capacity, which is the target of the belt torque capacity, can be lowered, and the pinching pressure applied to the belt 35 can be reduced. By reducing the pinching pressure, it is possible to reduce the energy loss and, by extension, improve the fuel efficiency of the vehicle 1.

Further, by providing an appropriate interval between the time when the new margin is set and the time when the margin is updated, it is possible to prevent the durability from being lowered due to the frequent slip of the forward clutch 52. , The margin allowance can be managed accurately.

The threshold value used for detecting the occurrence of slip of the forward clutch 52 is set according to an arithmetic expression that adds the first correction term, the second correction term, and the third correction term. The first correction term is a term considering an error due to play in the rotation direction between the rotating body for generating the pulse signal of the front rotation speed sensor 64 and the primary input gear 51, and the second correction term is the front rotation speed. It is a term considering that the front rotation number N1 acquired from the detection signal of the sensor 64 is delayed with respect to the true value, and the third correction term is the true value of the interval of the pulse signal output by the front rotation number sensor 64. On the other hand, it is a term that considers the error of the value obtained by quantizing it.

Therefore, by including the first correction term, the second correction term, and the third correction term in the calculation formula for setting the threshold value, the error included in the absolute value of the difference between the front rotation number and the rear rotation number can be ignored. The threshold can be set to a small value. As the threshold value is smaller, the occurrence of slip can be determined at the stage where the difference between the front rotation speed and the rear rotation speed due to the slip of the forward clutch 52 is small, so that the occurrence of slip of the forward clutch 52 can be detected at an early stage. ..

As a result, even if the forward clutch 52 slips and is repeatedly re-engaged, the shock due to the re-engagement of the forward clutch 52 is small, so that it is possible to suppress a decrease in the durability of the forward clutch 52. Therefore, the number of times the margin allowance is reset can be increased, and the margin allowance can be managed more accurately.

<Modification example>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other embodiments.

For example, in the above-described embodiment, the calculation formula for setting the threshold value includes the first correction term, the second correction term, and the third correction term, but the calculation formula for setting the threshold value includes the first correction term and the second correction term. By including at least one of the correction term and the third correction term, the threshold value can be set to a smaller value as compared with the conventional one, and the occurrence of slip of the forward clutch 52 can be detected at an early stage.

Further, a constant term may be further added to the arithmetic expression for setting the threshold value as a margin allowance for the theoretical value.

The engine 2 and the speed change unit 4 may be controlled by separate ECUs. In that case, the present invention is applied to the ECU that controls the speed change unit 4. The engine rotation speed sensor 62 and the accelerator sensor 63 are connected to the ECU that controls the engine 2, the engine rotation speed and the accelerator opening are calculated by the ECU that controls the engine 2, and the engine rotation speed and the accelerator opening are the engine 2. It may be transmitted from the controlling ECU to the controlling ECU of the speed change unit 4.

In addition, various design changes can be made to the above-mentioned configuration within the scope of the matters described in the claims.

1: Vehicle 2: Engine (drive source)
7L, 7R: Drive wheel 22: Continuously variable transmission mechanism 33: Primary pulley 34: Secondary pulley 35: Belt 52: Forward clutch 61: ECU (Vehicle control device, target clutch torque capacity setting means, margin setting means)

Claims (1)

Power transmission in the power transmission path in series with a continuously variable transmission mechanism in which an endless belt is wound around a primary pulley and a secondary pulley on a power transmission path between a drive source and a drive wheel. A device used in a vehicle provided with a friction clutch that is engaged / disengaged to allow / prevent the friction clutch, and is a device that detects the occurrence of slip of the friction clutch.
Comparing the difference between the front rotation speed of the friction clutch on the drive source side and the rear rotation speed of the friction clutch on the drive wheel side and the threshold value, the absolute value of the difference is equal to or greater than the threshold value. The slip generation determination means for determining the occurrence of the friction clutch slip, and the slip generation determination means.
The first correction term proportional to the setting value, inversely proportional to the setting value, and proportional to the time change rate of the setting value, with the value based on the front rotation number or the rear rotation number as the setting value. A slip generation detection device including a threshold setting means for setting the threshold according to an arithmetic expression including at least one of the second correction term and the third correction term proportional to the squared value of the setting value.

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