JPH0611022A - Controlling method for v-belt type continuously variable transmission and controller therefor - Google Patents

Abstract

PURPOSE:To detect sliding between a V-belt and a pulley at a now cost and restrain this sliding in a V-belt type continuously variable transmission. CONSTITUTION:A real speed change ratio calculator 31 calculates a real speed change ratio 32 on the basis of detection signals output from a driving pulley rotation speed sensor 18 and a driven pulley rotation speed sensor 19, and further, a real speed change rate detector 33 calculates a real speed change rate. A theoretical speed change rate detector 36 calculates a theoretical speed change rate based on the real speed change ratio 32, an engine speed, a throttle valve opening degree, and a control quantity of a speed change control valve 13. A comparator (belt sliding detector) 38 compares a real speed change rate with the theoretical speed change rate so as to detect whether or not belt sliding is generated. If belt sliding is generated, a line pressure indicator 4C receives a signal, to thus increase a line pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed change control device, and more particularly to a V-belt stepless speed change control device.

[0002]

2. Description of the Related Art In recent years, as an alternative to a conventional torque converter type stepped automatic transmission as a vehicle transmission,
Continuously variable transmission (CVT: Cont
The development of inuously variable transmission) is being actively conducted. As a concrete mechanism of this CVT, hydraulic pressure is applied to the pulley chambers of the drive pulley and the driven pulley in which the V-shaped groove intervals are variable to change the groove intervals, thereby changing the running diameter of the belt and changing the gear ratio. There is a V-belt type continuously variable transmission that controls the.

With this type of transmission, it is important to control the pressing force of the hydraulic pressure of the drive pulley and the driven pulley to the minimum necessary value for the transmission torque. The first is to reduce the pushing force of the pulley to ensure the durability of the V-belt, and secondly to reduce the load on the oil pump, which in turn reduces the engine load and improves fuel economy. There are two requests to try.

Japanese Patent Publication No. 2-45062 discloses a technique related to line pressure control of a V-belt type continuously variable transmission. In this conventional technique, a two-dimensional map corresponding to the output torque and the gear ratio of the engine is set in a storage device of a microcomputer, and the line pressure is controlled in an open loop by searching the two-dimensional map. Trying to.

Further, in this prior art, it is clarified that the pressing pressure Q1 of the driving pulley and the pressing pressure Q2 of the driven pulley must satisfy at least the following expression 1 in order to prevent the V-belt from slipping. .

[0006]

[Equation 1]

Here, Tin is an input torque applied to the drive pulley, θ is a half of the apex angle of the pulley groove, μ is a coefficient of friction between the V belt and the pulley, Rin is a belt running radius of the drive pulley.

Further, when the pressing pressure Q1 of the driving pulley and the pressing pressure Q2 of the driven pulley do not satisfy the above formula 1, V-belt slippage occurs, but the following technique is known to detect this phenomenon. Has been.

In Japanese Patent Laid-Open No. 63-62954, the theoretical gear ratio is obtained by detecting the axial movement amount of one or both of the driving pulley and the driven pulley, and at the same time, the ratio of the rotational speeds of both the driving pulley and the driven pulley is calculated. A technique is known in which an actual gear ratio is obtained from the above, and when the two values do not match, the belt slip is determined.

Further, in Japanese Patent Laid-Open No. 62-68142, when the value of the actual gear ratio obtained from the rotational speed ratio of the drive pulley and the driven pulley deviates from the maximum or minimum gear ratio on the mechanism,
Alternatively, when the value of the speed change speed determined based on the deviation between the target speed change ratio and the actual speed change ratio deviates from the maximum speed change speed on the mechanism, it is determined that the belt slips.

[0011]

However, in the prior art disclosed in Japanese Patent Publication No. 2-45062, since the line pressure is controlled by the open loop, the minimum necessary line pressure is stored in the map. I can't keep it. This is because the friction coefficient decreases due to the wear state of the belt and the pulley over time, and in the case of the metal V-belt, the characteristics of the speed change oil entering between the interface between the belt and the pulley. As the coefficient of friction decreases, the required required line pressure increases, as is clear from Equation 1 above.

Therefore, this means that when setting the line pressure value, not only the line pressure value itself derived from Equation 1 above, but also a large value that takes into consideration the safety compensation due to changes over time and other factors must be set. It means that it must be done. Excessive load is applied in the width direction of the V-belt to that extent, which shortens the belt life, reduces the transmission efficiency of the transmission mechanism itself, and increases the load on the oil pump, which causes a reduction in engine efficiency. .

Also from the viewpoint of fail-safe, the open loop control has a drawback that the operation is not permanently corrected when a problem occurs.
That is, even if the control device outputs an accurate indication value of the line pressure, if the line pressure falls for some reason (discharging force drop due to oil pump failure, pressure leak of hydraulic system, etc.), traveling is no longer possible. There is a problem that it will be possible.

Further, as a conventional technique for detecting belt slippage, Japanese Patent Laid-Open No. 63-62954 detects theoretical belt slippage, but in order to detect the amount of axial movement of a drive pulley or a driven pulley. In addition, a sensor or a special link mechanism is required, which has a disadvantage of high cost.

Further, in Japanese Patent Laid-Open No. 62-68142, which is a conventional technique for detecting belt slippage, a value of a speed change speed is used for detecting belt slippage, and a speed change determined based on a deviation between a target speed change ratio and an actual speed change ratio. When the speed value deviates from the maximum shift speed of the mechanism, it is determined that the belt slip.

However, the shift speed described in this prior art is a control target value that is determined based on the deviation between the target speed ratio and the actual speed ratio and that the continuously variable transmission mechanism should change the speed ratio. Moreover, no theoretical description has been made as to what basis determines the maximum speed change speed of the mechanism to be compared.

The speed change speed of this prior art is not directly related to the behavior of the actual speed change ratio. This is because it is derived as a coefficient multiple of the difference between the target gear ratio and the actual gear ratio. Moreover,
Since the control target value is used in the shift control, the shift control content and the belt slip detection are inseparable. Therefore, there is a problem that the detection sensitivity of belt slip also changes when the control content changes due to matching of vehicle types, and there is a problem that shift control and belt slip detection are not independent.

In addition to the above-mentioned conventional technique, a rotational speed sensor for the driving pulley, a rotational speed sensor for the driven pulley, a torque sensor for the CVT input shaft, and a torque sensor for the CVT output shaft are provided. Prior art disclosed in Japanese Patent Laid-Open No. 58-214054, which detects the belt slip from the detected value of the belt, a sensor for detecting the rotational speed of each of the driving side pulley and the driven side pulley, and a sensor for detecting the V belt speed. And the prior art disclosed in Japanese Patent Application Laid-Open No. 62-292950 for detecting belt slip from these detected values,
Similarly, a sensor for detecting the rotational speed of each of the driving side and driven side pulleys and a stroke sensor for detecting the gear ratio by detecting the stroke amount of the pulley in the axial direction are provided. Actual Kaihei 1-1563 to detect
Although there is a conventional technique described in Japanese Patent Publication No. 49, there is a problem that the number of sensors newly provided for detecting belt slip is large, which is disadvantageous in cost.

The object of the present invention is to solve the above-mentioned problems of the prior art and to eliminate the need for a special sensor in software processing.
An object of the present invention is to provide a V-belt type continuously variable transmission in which the contents of the shift control and the belt slip detection mechanism are independent of each other and are not affected by changes in the contents of the shift control.

[0020]

In order to control the line pressure of a V-belt type continuously variable transmission, a means for self-detecting belt slip is provided, and when the belt slip is detected, the line pressure is divided by a predetermined amount. It is achieved by increasing (claims 1, 9, 10).

The above object is also to hold a line pressure value for each operating state, which is a basic value for line pressure control, in a RAM (Random Access Memory) in a microcomputer,
RAM when the required pressure is insufficient and belt slippage occurs
This is achieved by correcting the above applicable value in the increasing direction and providing learning means for controlling the line pressure value to an optimum value at all times (claim 2).

The above object is also achieved by providing a means for coping with the occurrence of belt slippage by reducing the gear ratio rather than controlling the line pressure as in claim 1. (Claim 3).

The above object is also achieved by storing the time point when the belt slips and the driving state at that time in the RAM, transmitting the information to the driver or the maintenance person, and performing self-diagnosis. (Claim 4).

The above object is also to send the information to an electronically controlled throttle valve control device to reduce the throttle valve opening and not to increase the line pressure when the belt slip occurs. This is achieved by reducing the amount and reducing the engine torque to prevent belt slippage (claim 5).

The above object is also to send the information to the engine control unit to retard the ignition advance angle of the engine when the belt slip occurs, instead of increasing the line pressure as in the fifth aspect. This is achieved by reducing engine torque and preventing belt slippage (claim 6).

[0026] The above object is also as an alternative to claim 6,
When belt slippage occurs, the information is sent to the engine control device in the same manner as in claim 6, but the amount of fuel supplied to the engine is reduced instead of retarding the ignition advance angle of the engine. This is achieved by lowering the engine torque and preventing belt slippage (Claim 7).

[0027]

In the inventions of the above claims, as the sensors newly prepared for detecting the belt slip, it is only necessary to provide the sensors for detecting the pulley rotation speed signals of the driving side and the driven side or the corresponding signals. .

The inventions of claims 1, 9 and 10 describe a mechanism for detecting belt slippage in a V-belt type continuously variable transmission. From the geometrical condition that the circumference of the V-belt is constant, the rate of change of the gear ratio when a predetermined flow rate change is applied to the shift control valve is uniquely obtained. From this and the time change of the actual speed ratio when actually changing the speed change control valve, the actual speed ratio change rate is calculated,
Belt slippage can be detected by comparison with the above values.

This is because the belt running diameter in the V-belt type continuously variable transmission can take only a value satisfying the above-mentioned geometric constraint condition. However, when the pressing pressure of the pulley is insufficient and the belt slips, the same effect as if the belt circumferential length is extended is provided.
The gear ratio changes to the low side (large value side) with a large rate of change.

A mechanism for predicting the theoretical rate of change of the gear ratio from the flow control valve flow rate and the geometrical constraint of the belt is claimed in claim 1.
The "theoretical shift change rate predicting means" and the actual shift change rate calculating means are the "actual shift change rate calculating means". So by comparing these two values,
It is possible to detect the breakage of the above-mentioned geometrical relationship, and it has the effect of detecting the slippage of the belt. Therefore, the function of detecting the belt slip is a basic and essential part of the configuration according to the invention described in the other claims.

In addition to this, in the first aspect, the function of increasing the line pressure by a predetermined amount when the belt slip is detected to eliminate the belt slip is realized. The increase of the line pressure is performed every time the belt slip is detected while observing the response of the change of the gear ratio. Therefore, even if the line pressure drops below the indicated value due to a decrease in discharge force due to a failure of the oil pump, a pressure leak in the hydraulic system, or the like, the present invention attempts to repair as much as possible.

According to a second aspect of the present invention, the line pressure value is held as a map on a rewritable storage device, the judgment value of the belt slip detection mechanism is used as a teacher signal, and the line pressure value is updated by updating the value. Perform learning control.

According to the third aspect of the present invention, when belt slippage occurs, this is avoided by reducing the gear ratio. As is clear from Equation 1, the pulley pressing pressure required to prevent the belt from slipping is inversely proportional to the belt running diameter of the drive pulley. Therefore, the belt slip can be stopped by reducing the gear ratio and increasing the running diameter.

According to a fourth aspect, the judgment value of the belt slip detection mechanism is applied to self-diagnosis. As a result, the self-diagnosis function can be enhanced without adding redundant sensors.

According to the present invention, when the belt slip occurs, the throttle opening is reduced to suppress the engine torque to avoid it. As is clear from Equation 1, the pulley pressing pressure required to prevent the belt from slipping is proportional to the input torque applied to the drive pulley, that is, the engine torque. Therefore, belt slippage can be stopped by suppressing the engine torque.

Belt slip is likely to occur in a region where the torque generated by the engine is large and the gear ratio is large. Once the belt slippage occurs, the engine tends to blow up together with the decrease in the coefficient of friction between the pulley and the belt. Therefore, when viewed as fail-safe, it makes more sense to suppress the engine torque, and the response speed is faster.

The sixth and seventh aspects are the fifth and fifth aspects.
In the same manner as above, the engine torque is suppressed to avoid belt slip. With this configuration, since the continuously variable transmission and the engine control device may cooperate with each other, there is an advantage that they can be easily executed by utilizing the current component structure of the vehicle.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a vehicle equipped with a V-belt type continuously variable transmission and a control device therefor according to an embodiment of the present invention. The torque generated from the engine 1 can be directly connected (this is referred to as a lock-up function).
It is input to the drive pulley 3 of the V-belt type continuously variable transmission via the converter 2. The torque input to the drive pulley 3 is transmitted to the driven pulley 5 via the V belt 4.

The drive pulley 3 and the driven pulley 5 are each 2
Equipped with a pair of opposed rotating plates, one rotating plate is fixed,
The other is designed to change its position in the direction of the rotation axis by the action of hydraulic pressure. As a result, the gap between the pulleys is adjusted, which in turn changes the running diameter of the V-belt to perform a gear shifting action. The torque transmitted to the driven pulley 5 by the speed change action enters the final reduction gear 6 and is finally transmitted to the drive wheels 7.

On the other hand, describing the path of the hydraulic system, the oil sucked by the pump 11 from the oil sump 9 through the oil filter 10 is discharged to the oil passage 8. The oil pressure in the oil passage 8 is generally called a line pressure, which is regulated by the line pressure control valve 12 and serves as a basic pressure for gear shifting operation.

The line pressure control valve 12 is an electromagnetic proportional control valve, which receives an instruction pressure calculated in the stepless speed change control device 15 having a built-in microcomputer by the electric path 16 and performs electromagnetic / hydraulic conversion. , Control the line pressure.

The line pressure is introduced into the driven pulley cylinder oil chamber 5a through the oil passage 8, is appropriately reduced in pressure through the speed change control valve 13, and is also introduced into the drive pulley cylinder oil chamber 3a through the oil passage 14.

The shift control valve 13 is an electromagnetic proportional control valve, and like the line pressure control valve 12, the continuously variable shift control device 1
5 receives a signal from the electric path 17 and performs electromagnetic / hydraulic conversion to control the hydraulic pressure of the oil passage 14.

It should be noted that the signal flowing through the electric path 17 indicates the absolute pressure of the oil pressure in the oil passage 14, and the ratio of the oil pressure in the oil passage 14 to the line pressure (the oil pressure in the oil passage 8). That is not to do. Even if the indicated value becomes larger than the line pressure, the upper limit of the pressure in the drive pulley cylinder oil chamber 3a is limited by the line pressure. Therefore, the oil pressure of the oil passage 14 is never controlled to be higher than the line pressure.

Considering this, the pressure receiving area of the drive pulley cylinder oil chamber 3a in the axial direction is determined by the driven pulley cylinder oil chamber 5a.
It is set almost twice as large as that of a. As a result, the belt pressing pressure of the drive pulley 3 is reduced by the driven pulley 5
It is possible to control to a range exceeding the pressing pressure of, and it is possible to realize an arbitrary pressing pressure ratio (ratio between the driving pulley pressing pressure and the driven pulley pressing pressure). Therefore, it is possible to operate from the high speed ratio (Low side) to the low speed ratio (High side) only with the line pressure control valve 12 and the speed change control valve 13.

The drive pulley rotation speed sensor 18 transmits the rotation speed of the drive pulley 3 to the continuously variable transmission control device 15 as an electric signal. The sensor 18 may be replaced by the engine rotation speed sensor 20 if the direct / indirect connection information of the torque converter 2 and the rotational speed ratio of the pump and the turbine are known.

Further, the driven pulley rotation speed sensor 19 is
The rotation speed of the driven pulley 5 is transmitted to the continuously variable transmission control device 15 as an electric signal. The driven pulley rotation speed sensor 19 does not have to directly detect the rotation speed of the driven pulley 5, but may also detect the rotation speeds of the drive shaft of the vehicle and the final reduction gear (that is, vehicle speed). good.

The stepless speed change control device 15 calculates the actual speed change ratio by taking the ratio of the rotational speeds of the drive pulley 3 and the driven pulley 5.

The engine speed sensor 20 and the throttle sensor 21 give signals necessary for estimating engine generated torque. Instead of the engine speed sensor 20, a crank angle signal or an ignition timing signal used by the engine control device 25 may be used. Further, the throttle sensor 21 can be replaced with a sensor that captures the intake pipe negative pressure or the mass air flow rate of the engine.

Apart from the above embodiment, the throttle valve control device 23 and the electronically controlled throttle device 22 shown together in FIG. 1 are the elements necessary for the construction of claim 5.
The throttle valve control device 23 controls the intake air amount of the engine by sending a throttle valve opening signal to the electronic control throttle device 22. This device 23 receives a signal instructed through the electric path 24 when the continuously variable transmission control device 15 detects belt slip, reduces the opening of the throttle valve, and suppresses the torque generated by the engine.

The engine control device 25 is an element required for the configurations of claims 6 and 7. This device 25
Controls the engine ignition timing signal 26 and the fuel injection signal 27. The device 25 receives a signal commanded through the electrical path 28 when the continuously variable transmission control device 15 detects a belt slip, and the ignition timing signal 26 according to the configuration of claim 6 is received.
Is retarded, and the fuel injection signal 27 is reduced from the normal amount in the structure of claim 7 to suppress the torque generated by the engine.

FIG. 2 is a block diagram showing the internal structure of the continuously variable shift control device 15. Each element of the internal configuration shown in FIG. 2 is realized mainly by control software of a microcomputer incorporated in the continuously variable transmission control device 15. Of the internal structure, the block surrounded by the frame 30 is a part based on the constituent elements of claim 1.

The actual gear ratio calculating means 31 takes the ratio of the speeds obtained from the drive pulley rotation speed sensor 18 and the driven pulley rotation speed sensor 19 and outputs an actual gear ratio signal 32.
In addition, the actual shift change rate detection means 33 includes a shift instruction means 34.
While the control amount for the shift control valve 13 is being updated, the difference between the time-series values of the actual gear ratio signal 32 is calculated, and the actual gear change rate signal 35 (described later as Δi) is output.

On the other hand, the theoretical gear change rate detecting means 36 includes the actual gear ratio signal 32 and the engine speed sensor 20,
The theoretical shift change rate signal 37 (which will be described later as Δi0) from each information of the control amounts of the throttle sensor 21 and the shift control valve 13.
Is output. The theoretical shift change rate detecting means 36
Only monitors the output of the shift instruction means 34 to the shift control valve 13, and is independent of the portion that controls the shift.

The belt slip detection means 38 compares the actual gear change rate signal 35 with the theoretical gear change rate signal 37, and when the former becomes larger than the latter, the belt slip detection signal 39.
Is output.

In the invention of claim 1, the signal 39 is sent to the line pressure instructing means 40, and the operation of changing the control amount of the line pressure control valve 12 to raise the line pressure by a predetermined amount is performed.

In the second aspect of the invention, the belt slip detection signal 39 is sent to the line pressure map storage means 41 which is also shown in FIG. Line pressure map storage means 41
Instructs the line pressure instructing means 40 to generate a line pressure value according to the operating conditions. Therefore, the line pressure map storage means 41 can learn and store the line pressure value of the corresponding operating condition so that there is no belt slip, using the belt slip detection signal 39 as a teacher signal.

According to the third aspect of the invention, the belt slip detection signal 39 is transmitted to the gear shift instructing means 34 shown in FIG.
Sent to. The gear shift instructing means 34 reduces the gear ratio to prevent the belt slip when the belt slip is detected.

In the fourth aspect of the invention, the belt slip detection signal 39 is sent to the self-diagnosis storage means 42 which is also shown in FIG. The self-diagnosis storage means 42 can store the event of belt slip and the driving condition that occurred to enhance the self-diagnosis function of the system.

In the fifth aspect of the invention, the belt slip detection signal 39 is sent to the external throttle valve control device 23 shown in FIG. 2 through the electric path 24. In response to this command, the throttle valve control device 23 operates the throttle valve opening and reduces the engine torque by a predetermined amount to suppress belt slip.

In the inventions of claims 6 and 7, the belt slip detection signal 39 is sent to the external engine control unit 25 also shown in FIG. 2 through the electric path 28. In response to this command, the engine control unit 25 retards the ignition timing in the invention of claim 6 and reduces the amount of fuel in the invention of claim 7 to reduce the engine torque by a predetermined amount to prevent belt slippage. Suppress.

In each form of the invention of claims 2 to 7, the signal transmission path of the belt slip detection signal 39 is as shown in FIG.
It is shown as a wavy line diverging from the belt slip detection signal 39 therein.

The most important one of the above constituent elements is the theoretical shift change rate detecting means 36. The operating principle of this block will be described below. The geometry of the V-belt is shown in FIG. To explain the symbols in FIG. 3, Rin: Belt running diameter of drive pulley 3 Rout: Belt running diameter of driven pulley 5 a: Axial distance between drive pulley and driven pulley L: Belt circumference of V belt ψ : A perpendicular line that connects the centers of the pulleys with respect to a perpendicular line that rises from the centers of the pulleys. The separation angle at which the contact point between the pulley and the V belt is stretched. It is a negative value and expressed in radians.

Here, the speed ratio i of the V-belt speed change mechanism is

[0065]

[Equation 2]

[Mathematical formula-see original document] The following mathematical formulas 3 and 4 are derived from the geometrical constraint that the belt circumferential length L is constant and the mathematical formula 2.

[0067]

[Equation 3]

[0068]

[Equation 4]

By combining these equations 3 and 4,

[0070]

[Equation 5]

Solving for the gear ratio i using the approximation of

[0072]

[Equation 6]

Is obtained. Also, when solving with Rin,

[0074]

[Equation 7]

Is obtained. Therefore, the rate of change of the gear ratio i with respect to the change of the running diameter Rin of the V-belt in the drive pulley 3 is given by the following equation by differentiating Equation 6 with Rin.

[0076]

[Equation 8]

Next, the rate of change of the gear ratio i with respect to the volume change of the drive pulley cylinder oil chamber 3a is obtained.

A cross section of the drive pulley 3 is shown in FIG. To explain the symbols in FIG. 4, Vd: the volume of the drive pulley cylinder oil chamber 3a at the maximum gear ratio (when the pulley cylinder is contracted most), that is, the dead volume that does not contribute to the gear shifting operation S: the drive pulley Equivalent projected bottom area of cylinder oil chamber 3a LP: Axial stroke amount of movable side of drive pulley 3 Rin0: Minimum running diameter of V-belt at maximum gear ratio θ: Half-sheave angle at contact surface of pulley and belt (1/2 of the vertical angle of the pulley groove).

Here, if the volume of the drive pulley cylinder oil chamber 3a is VP, the following relational expression is established.

[0080]

[Equation 9]

When the two equations of equation 9 are made simultaneous and LP is eliminated, the following equation is obtained.

[0082]

[Equation 10]

Therefore, the rate of change of the drive pulley belt running diameter with respect to the volume change of the drive pulley cylinder oil chamber 3a is given by the following equation by differentiating the equation 10 by VP.

[0084]

[Equation 11]

Therefore, the rate of change of the gear ratio i with respect to the volume change of the drive pulley cylinder oil chamber 3a is obtained from the equations 8 and 11, and the following equation is obtained.

[0086]

[Equation 12]

On the other hand, when the flow rate of the shift control valve 13 is Q, assuming that the oil is an incompressible fluid, ΔVP = Q holds. By using this, the theoretical change rate Δi0 of the gear ratio i per unit time can be obtained from the following equation.

[0088]

[Equation 13]

Therefore, from the above discussion, Rin for an arbitrary gear ratio i can be obtained from Equation 7, and the obtained Rin
Using in, di / dVP can be calculated from Equation 12. Further, if the flow rate Q of the shift control valve 13 is known, the value of the equation 12 can be used to solve the equation 13.

Therefore, the table f (i) where di / dVP = f (i) can be calculated in advance and set in the theoretical shift change rate detecting means 36. By subtracting this table from the actual gear ratio i and multiplying it by the gear change control valve flow rate Q, the gear ratio change rate Δi0 when there is no belt slip can be calculated.

Next, a method for obtaining the flow rate Q of the shift control valve 13, which is necessary for the calculation of the above expression 13, will be briefly described below. In order to obtain the flow rate of the shift control valve 13, it is important to estimate the pressure in the drive pulley cylinder oil chamber 3a in the pressure control type proportional solenoid valve. A method for estimating this pressure will be shown first.

It is generally known that the following theoretical formula 14 is established between the pulley and the V-belt (Ogasawara: Shifting characteristics of V-belt automatic transmission: Production Research Vol. 1).
4, No. 6, pp183-186 (1962)).

[0093]

[Equation 14]

As described above, Q1 and Q2 in the above equation are the pressing forces of the drive pulley 3 and the driven pulley 5 against the V belt 4 in the axial direction. Further, A is an experimental coefficient, which may be treated as a constant in a normal use state.

Here, a pressing pressure ratio k between the pulleys is introduced such that Q1 = kQ2. Then, Equation 14 can be modified as follows.

[0096]

[Equation 15]

However, the constant B in the above equation 15 is defined as follows.

[0098]

[Equation 16]

Solving the equation of Equation 15 for ψ gives the following equation.

[0100]

[Equation 17]

On the other hand, the above equations 3 and 4 are solved for Rin to obtain the following equation.

[0102]

[Equation 18]

In Expression 16, Tin is equal to the engine torque when the torque converter 2 is locked up, and the pressing pressure Q2 of the driven pulley is a force proportional to the line pressure (product of line pressure and pressure receiving area).

Therefore, when the factor of Tin / Q2 in Expression 16, that is, the ratio of engine torque and line pressure is given, B is uniquely determined. Therefore, by performing mutual iterative calculation of Equation 17 and Equation 18 in advance,
It is possible to determine ψ and Rin for an arbitrary pressing pressure ratio k.

The procedure of this iterative calculation is shown in Equation 19 below.

[0106]

[Formula 19]

Once Rin is obtained, the gear ratio i can be uniquely obtained from the above equation 6, and the following equation can be derived from the above discussion.

[0108]

[Equation 20]

Here, Te is the output torque of the engine, P
L represents the line pressure and PP represents the pressure in the drive pulley cylinder oil chamber 3a. That is, the expression 20 means that if the speed ratio i is obtained from Tin / Q2 and the pressing pressure ratio k, Tin is equal to Te and k is proportional to PP / PL, so Te / PL and PP / P
That is, it is necessary and sufficient for the set of L values.

Therefore, when the set of the gear ratio i and the value of Te / PL is given, the inverse function f5 of the above equation for estimating the pressure PP at that time can be defined, and the following equation is derived.

[0111]

[Equation 21]

Here, Te is the above-mentioned throttle sensor 21.
And the value of the engine rotation speed sensor 20 can be easily estimated. Moreover, PL is the continuously variable transmission control device 1
5 is a value calculated by the line pressure instructing means 40 by itself and can be used internally. As the actual gear ratio i, the output value 32 of the actual gear ratio calculating means 31 can be used.

Further, the function f5 is calculated in advance by using an arbitrary gear ratio i.
It is possible to obtain a value for the set of the values of Te and PL by using the procedure of Expression 19, and store the value in the theoretical shift change rate detecting means 36 as a map. Therefore, even if it has the computing performance of the microcomputer, it can be sufficiently realized as real-time control.

Based on the above discussion, the drive pulley cylinder oil chamber 3
The method for estimating the pressure PP in a has been shown. If the estimated value of PP is known, the flow rate Q of the shift control valve 13 can be easily obtained. That is, when the shift instruction means 34 at that time makes the instruction pressure that is electrically instructing the shift control valve 13 to be P0, the following formula is established.

[0115]

[Equation 22]

Here, kU and kD are proportional constants determined by the orifice characteristics of the shift control valve 13. Therefore, as described above, the theoretical shift change rate detection means 3 is determined by the obtained Q.
If (Equation 13) is calculated in 6, the gear ratio change rate Δi0
Can be asked.

The gear ratio change rate Δi0 is extremely useful not only for detecting slippage of the belt as in the present invention but also for controlling the gear ratio. Although the following is not directly related to the present invention, as an application of Δi0,
An example in which this is used to control the shift control valve will be shown.

FIG. 5 is a control block diagram of the shift instruction means 34 in FIG. In the figure, Nin is the rotation speed of the drive pulley 3, and Nin0 is a target value at which the drive pulley rotation speed should be converged.

Generally, in the control of the continuously variable transmission, the gear ratio is controlled so that Nin follows the target drive pulley rotation speed Nin0 obtained from the vehicle speed and the throttle opening. The deviation between Nin and Nin0 is processed by the proportional gain K1 and the differential gain K2, and then the shift control valve 1
It is accumulated as a controlled variable of 3. The reason for using the integrator 50 is that a mechanism including a hydraulic circuit is generally a dead time system and compensates for an integration deviation (offset).

The block 51, which is the addition point of the proportional gain and the differential gain shown in the figure, improves the controllability in recent years.
It is also commonly replaced by a fuzzy controller, such as block 52 shown.

The problem here is that the system is a dead-time system, and therefore, even if Nin and Nin0 temporarily match in the process of convergence, a further excess control amount is accumulated in the integrator 50. , Nin does not stop near Nin0 and causes a large overshoot. By using the gear ratio change rate Δi0, it is possible to provide a determination value for limiting the overshoot of this control operation.

The block 53 calculates this judgment value and
It is applied to one end of the comparator 55. Here, i is the measured actual gear ratio, and i0 is the target gear ratio obtained by converting Nin0 by the current driven pulley rotation speed.

The meaning of the equation in the block 53 indicates that the deviation (i−i0) of the gear ratio is divided by the rate of change of the gear ratio (Δi0), and gives the predicted time until convergence as seen from the CVT mechanism.

A value obtained by dividing the control deviation e by the time change Δe of the control deviation is input to the other end of the comparator 55. This gives the predicted time to convergence in terms of the actual operating aspects of the system. The comparator 55 compares the two values, and when they are substantially coincident with each other, sends an instruction to the switch 56 to cut off the input of the integrator to prevent the overshoot control amount from being accumulated.

Therefore, as the control amount of the shift control valve 13,
The CVT mechanism can instruct the maximum speed that can theoretically be taken, but it does not go over the intended value. This makes it possible to improve the responsiveness and suppress the overshoot at the same time. Therefore, the followability with respect to the target value Nin0 is increased, so that the shift control with good fuel economy can be realized.

6 to 12 are flowcharts showing the operation procedure of the belt slippage detection mechanism according to the present invention described above.
Shown in. The flowcharts after FIG. 6 are periodically activated at every time interval for calculating the actual shift change rate.

In step 60, if the control amount of the shift control valve is being updated and the shift operation is being performed, the process proceeds to step 61. If not, the process proceeds to step 73. In step 73,
The actual gear ratio i is calculated in preparation for future belt slip determination. In step 61, the flow rate Q of the shift control valve is obtained as described above, and in the subsequent step 62, the theoretical gear ratio change rate Δi0 is calculated.

Since the control amount of the shift control valve is being updated, the actual gear ratio changes as a result. Step 63 is to calculate this new actual gear ratio,
This is performed by the actual gear ratio calculation means 31 of FIG. Since the previous actual speed ratio is calculated in step 73 and stored in step 74, the actual speed change rate Δi is obtained in step 64 by taking the difference between the two values. Note that this calculation is performed by the actual shift change rate detection means 33 in FIG.

At step 65, Δi and Δi thus obtained are calculated.
Belt slippage is detected by comparing the values of 0. If belt slippage is detected, the process proceeds to step 66, and if not detected, the process proceeds to step 74. This belt slip detection is shown in FIG.
In the above, the belt slippage detection means 38 performs.

Step 66 is the control method according to the first aspect of the present invention. When belt slip is detected, the line pressure is increased by a predetermined amount to suppress belt slip.

The flowchart of FIG. 7 is based on the method according to the invention of claim 2. Step 6 compared to FIG.
6 has been replaced by step 67. If belt slippage is not detected in step 65, the line pressure map value in the operating state, which is the reference value of the line pressure control, is decreased in step 67a with a predetermined time constant. On the contrary, if the belt slip is detected, the line pressure map value is increased by a predetermined amount in step 67b. By this method, it becomes possible to learn the optimum line pressure value in the corresponding operating condition.

The difference between the correction methods of the line pressure value described above is the difference between the transient control that does not leave a history in the line pressure map storage means in FIG. 2 and the learning control that leaves a history. It goes without saying that step 67 is used exclusively in terms of the method.

The flowchart of FIG. 8 is based on the method according to the invention of claim 3, and the step 6 in comparison with FIG.
6 has been replaced by step 68. Unlike Figure 6,
When belt slip is detected, the gear ratio is temporarily reduced to avoid this. This is because the required line pressure may be low if the gear ratio is reduced and the belt running diameter of the drive pulley is increased. This can be used when the line pressure value cannot be corrected and the belt slippage cannot be stopped due to a failure of the oil pump or the like, that is, as a line pressure fail-safe.

The flowchart of FIG. 9 is based on the method according to the invention of claim 4, and the step 6 is different from that of FIG.
6 has been replaced by step 69. Unlike the above-described embodiment, the belt slippage detection means based on the gear ratio change rate Δi0 is applied to self-diagnosis. As a result, belt slippage can be detected by the minimum necessary sensor that is originally included in the continuously variable transmission control device, which is a great cost advantage.

The flowchart of FIG. 10 is based on the method according to the fifth aspect of the present invention, and step 66 is replaced with step 70 as compared with FIG. In this flowchart, the electronically controlled throttle device 22 and the throttle valve control device 23 shown in FIG. 1 are required as constituent elements. When the belt slip is detected, the throttle valve controller 23 is instructed to decrease the throttle valve opening to suppress the engine torque and stop the belt slip.

The flowchart of FIG. 11 is based on the method according to the invention of claim 6, step 66 is replaced with step 71 as compared with FIG. In this flowchart, the engine control device 25 shown in FIG.
Is required as a component. When the belt slip is detected, a retard instruction signal for ignition timing is issued to the engine control device 25 to suppress the engine torque. This functional step realizes the same purpose as step 70 in the flowchart of FIG. 10 by changing the means.

The flowchart of FIG. 12 is based on the method according to the invention of claim 7, step 66 is replaced with step 72 as compared with FIG. Also in this flowchart, the engine control device 25 is required as a constituent element. The effect of suppressing the engine torque by outputting the fuel injection amount reduction instruction signal to the engine control device 25 when the belt slip is detected is the same as in FIG.

[0138]

According to the present invention, a reference value for detecting belt slip can be easily added to the system by looking at the rate of change of the actual gear ratio. Therefore, there is an effect that a special sensor for detecting the belt slip is not required and the cost is not increased.

Further, this belt slip detection mechanism is independent of the shift control, and has the advantage that it is not affected by changes due to matching of shift control contents and changes by model.

In addition, the derivation of the belt slipping judgment reference value can be carried out by searching a table obtained by numerical calculation in advance for most of the calculation process. As a result, there is an effect that satisfactory real-time responsiveness can be obtained even in a device to which a microcomputer having a weak numerical calculation performance is applied.

Further, when the belt slip is detected, the belt slip is suppressed by increasing the line pressure, and there is an effect that the durability of the belt and the sheave surface of the pulley are promptly protected from abrasion. In addition, this protection operation is repeatedly performed until the belt slip is no longer detected by the closed loop control, which has the effect of enhancing the robustness of the system.

On the other hand, by using this belt slip signal as a teacher signal to correct the line pressure value in the corresponding operating condition,
Learning control of line pressure can be realized. In this learning control, it is not necessary to set the line pressure to a large value in advance in anticipation of a change with time. Therefore, since the system always operates with the minimum required line pressure, there is an effect that the pump load can be reduced and the fuel efficiency of the vehicle can be greatly improved. Further, since the pressing pressure of the pulley is adjusted appropriately, the power transmission efficiency of the V-belt type continuously variable transmission itself is also improved, which also contributes greatly to the improvement of fuel consumption.

Further, there is also disclosed a method of reducing the gear ratio when belt slippage is detected to suppress it. When the pump discharge pressure drops for some reason, belt slippage can be suppressed without increasing the line pressure, which is effective for fail-safe protection of the belt and the pulley.

The detection of the belt slip also has the effect of significantly enhancing the self-diagnosis function of the system. By storing the time when the belt slips and the driving state at that time and transmitting the information to the driver or the maintenance person, great convenience is provided in the self-diagnosis function. Moreover, the hardware mechanism can be executed by software processing without adding anything, so that the cost does not increase.

The belt slip detection signal can also be exchanged with other control devices, that is, the throttle valve control device and the engine control device. Therefore, if belt slippage occurs, measures can be taken to quickly suppress the engine torque in cooperation with external equipment.

This is an important control method in order to prevent the driver from feeling uncomfortable due to the engine running up and to control the system on the safe side when viewed as a fail safe.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is an internal configuration diagram of a continuously variable transmission control device.

FIG. 3 is a geometrical view of a V-belt.

FIG. 4 is a geometrical sectional view of a drive pulley.

FIG. 5 is a control block diagram of a shift instruction means.

FIG. 6 is a flowchart showing an embodiment of the invention according to claim 1;

FIG. 7 is a flowchart showing an embodiment of the invention according to claim 2;

FIG. 8 is a flowchart showing an embodiment of the invention according to claim 3;

FIG. 9 is a flowchart showing an embodiment according to the invention of claim 4;

FIG. 10 is a flowchart showing an embodiment according to the invention of claim 5;

FIG. 11 is a flowchart showing an embodiment according to the invention of claim 6;

FIG. 12 is a flowchart showing an embodiment according to the invention of claim 7;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Torque converter, 3 ... Drive pulley, 3a ... Drive pulley cylinder oil chamber, 4 ... V belt, 5
... driven pulley, 5a ... driven pulley cylinder oil chamber, 6 ... final reducer, 7 ... drive wheel, 8 ... line pressure oil passage, 9 ... oil sump, 10 ... oil filter, 11 ... oil pump, 12 ... Line pressure control valve, 13 ... Shift control valve, 14
... Oil path to drive pulley, 15 ... Continuously variable transmission control device, 1
8 ... Drive pulley rotation speed sensor, 19 ... Driven pulley rotation speed sensor, 20 ... Engine rotation speed sensor, 21 ... Throttle sensor, 22 ... Electronically controlled throttle device, 23
... Throttle valve control device, 25 ... Engine control device.

Claims (10)

[Claims] 1. A V-belt is wound around a drive pulley and a driven pulley having variable V-shaped groove intervals to transmit torque, and line pressure is constantly applied to a pulley chamber formed on the driven pulley side. A V-belt type continuously variable transmission device for a vehicle that changes the running diameter of a belt by applying a hydraulic pressure obtained by adjusting a line pressure by a shift control valve in a pulley chamber formed on the side of the drive pulley to change gears. In the control device, the actual gear ratio calculating means for calculating the actual gear ratio by comparing the drive pulley rotation speed signal obtained from the drive pulley rotation speed sensor with the driven pulley rotation speed obtained from the driven pulley rotation speed sensor. And a speed change control valve flow rate obtained by monitoring a control command of the speed change control valve independently of at what speed the speed ratio is changed in the actual speed change control, A theoretical speed change rate predicting means for predicting the speed change rate of the speed ratio per unit time, which is derived from a mechanical constraint condition that the belt circumference is constant, and a time series signal obtained from the actual speed ratio calculating means momentarily. The actual shift change rate calculating means for calculating the actual shift change rate, the value obtained by the theoretical shift change rate calculating means, and the value obtained by the actual shift change rate detecting means are compared. V-belt type stepless speed change control, characterized in that it comprises a belt slip detecting means for detecting the belt slip of the V belt, and a means for increasing the line pressure when the belt slip is detected by the belt slip detecting means. apparatus. 2. A means for holding a line pressure value according to an operating condition in a rewritable storage device in a microcomputer according to claim 1, and the storage when the belt slip is detected by the belt slip detection means. A V-belt type continuously variable transmission control device, comprising: means for correcting a line pressure value corresponding to a current operating state in the device and learning the line pressure value. 3. The V-belt type continuously variable transmission control device according to claim 1, further comprising means for reducing a gear ratio when the belt slip detection means detects belt slip. 4. The device according to claim 1, further comprising means for storing the information in the storage device for the purpose of transmitting the information to the driver or the maintenance person when the belt slip detecting means detects the belt slip. V belt type stepless speed change control device. 5. In addition to the structure of claim 1, when control information is allowed to be exchanged with the throttle valve control device and the belt slip detection device detects belt slip, the throttle valve control device is controlled to set a throttle valve opening degree. A V-belt type continuously variable transmission control device comprising means for giving a predetermined instruction for the purpose of reducing the torque generated by the engine. 6. In addition to the configuration of claim 1, when control slippage is allowed between the engine control unit and the belt slippage is detected by the belt slippage detection unit, the engine control unit delays the ignition advance angle. And a means for giving a predetermined instruction for suppressing the torque generated by the engine. 7. In addition to the configuration of claim 1, when the belt slip detection device detects belt slip by allowing control information to be exchanged with the engine control device, the engine control device is caused to reduce the amount of fuel. And a means for giving a predetermined instruction for suppressing the torque generated by the engine. 8. A V-belt is wound around a drive pulley and a driven pulley having variable V-shaped groove intervals for torque transmission, and line pressure is constantly applied to a pulley chamber formed on the driven pulley side. At the same time, a V-belt type continuously variable transmission that changes the running diameter of the belt by changing the running diameter of the belt by applying hydraulic pressure to the pulley chamber formed on the drive pulley side to adjust the line pressure by the shift control valve is provided. In the mounted vehicle, the change rate of the actual gear ratio is calculated from the driving pulley rotation speed signal or the equivalent signal and the driven pulley rotation speed signal or the equivalent signal, and the shift obtained by monitoring the control command of the shift control valve The theoretical rate of change of the gear ratio per unit time is predicted from the control valve flow rate and the mechanical constraint condition that the circumference of the V belt is constant, and the actual rate of change of the gear ratio and the theoretical change are predicted. A method for detecting V-belt slippage, which comprises detecting the presence or absence of slippage of the V-belt by comparing with a rate. 9. A V-belt is wound around a drive pulley and a driven pulley having variable V-shaped groove intervals to transmit torque, and line pressure is constantly applied to a pulley chamber formed on the driven pulley side. At the same time, a V-belt type continuously variable transmission that changes the running diameter of the belt by changing the running diameter of the belt by applying hydraulic pressure to the pulley chamber formed on the drive pulley side to adjust the line pressure by the shift control valve is provided. In the installed vehicle, the change rate of the actual gear ratio is calculated from the drive pulley rotation speed signal or the equivalent signal and the driven pulley rotation speed signal or the equivalent signal, and the shift obtained by monitoring the control command of the shift control valve is obtained. The theoretical rate of change of the gear ratio per unit time is predicted from the control valve flow rate and the mechanical constraint condition that the circumference of the V belt is constant, and the actual rate of change of the gear ratio and the theoretical change are predicted. A method for controlling a V-belt type continuously variable transmission, characterized by detecting the presence or absence of slippage of the V-belt and increasing the line pressure when belt slippage is detected. 10. A V-belt is wound around a drive pulley and a driven pulley having variable V-shaped groove intervals to transmit torque, and line pressure is constantly applied to a pulley chamber formed on the driven pulley side. At the same time, a V-belt type continuously variable transmission that changes the running diameter of the belt by changing the running diameter of the belt by applying hydraulic pressure to the pulley chamber formed on the drive pulley side to adjust the line pressure by the shift control valve is provided. In the installed vehicle, means for calculating an actual rate of change of the gear ratio from the drive pulley rotation speed signal or the equivalent signal and the driven pulley rotation speed signal or the equivalent signal; Means for predicting a theoretical rate of change of the gear ratio per unit time based on the mechanical control conditions such as the shift control valve flow rate and the constant V-belt circumference, and the actual change of the gear ratio And a ratio of the theoretical change, the presence or absence of slippage of the V-belt is detected, and the line pressure is increased when belt slippage is detected. A vehicle equipped with a V-belt type continuously variable transmission.