JP3341634B2 - Control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a continuously variable transmission mounted on a vehicle, and more particularly to a control device for holding a belt wound around a pair of pulleys having variable groove widths. It is suitable for a device having a continuously variable transmission mechanism that variably controls the gear ratio by adjusting the groove width of the groove.

[0002]

2. Description of the Related Art As a control device for such a continuously variable transmission, for example, Japanese Patent Application Laid-Open No. Hei 8-20046 previously proposed by the present applicant has been proposed.
There is one described in Japanese Patent Publication No. As disclosed in this prior art, in controlling the gear ratio variably by adjusting the groove width of the pulley, the working fluid pressure is supplied to two cones constituting the pulley in order to prevent the belt from slipping. The belt is held between the two cones by the thrust, that is, the pressing force. The working fluid pressure supplied to the pulleys constituting the continuously variable transmission mechanism is referred to as line pressure in the related art.
For the purpose described above, the basic set pressure of the line pressure is generally increased according to the input load from the engine to prevent the belt from slipping. Further, in this conventional technique, for example, a centrifugal pressure generated by a high-speed rotation of a pulley (the working fluid supplied into the cylinder chamber of the pulley is pushed outward by centrifugal force, and as a result, the fluid pressure in the cylinder chamber becomes high. The line pressure is controlled such that the sum of the centrifugal pressure and the basic set pressure according to the input load is within a maximum value set in advance according to, for example, the gear ratio. ing. By the way, this line pressure is
The working fluid pressurized by the pump is regulated by a pressure regulating valve for a continuously variable transmission mechanism including, for example, a duty valve and a modifier valve. In that case, the duty ratio to the duty valve is adjusted. The line pressure can be controlled by a control signal.

[0003]

However, it has been found that, although the line pressure is adjusted and controlled according to the input load as described above, a problem may occur in the durability of the belt. More precisely, the belt used in this type of belt-type continuously variable transmission is called a so-called push-type belt, and for example, a thin metal plate called an element is formed in a longitudinal direction or a winding direction of the belt. It is configured side by side. The durability of the belt to the line pressure, that is, the durability to the pressing force from the side, is also affected by, for example, the winding angle of the belt around the pulley and the rotation speed of the pulley, that is, the peripheral speed of the belt. That is, when the wrapping angle around the pulley is small, for example, the lateral load of the element alone becomes large, and the durability is reduced. In addition, when the peripheral speed increases, the centrifugal force of the belt increases, but the groove of the pulley has a V-shaped cross section that expands on the outer peripheral side, so that the pressing force from the side promotes the centrifugal force of the belt. As a result, the belt slips and elongates, and the durability is reduced. Of course, the set line pressure according to the input load from the engine is set to a value much smaller than the fluid pressure level affecting the durability of the belt in this way. Eventually, the total line pressure reaches a level that affects the durability of the belt.

The present invention has been developed in view of these problems. The working fluid pressure supplied to the pulley of the continuously variable transmission mechanism, such as the line pressure, is controlled by a set value determined by the speed ratio and the input rotation speed. It is an object of the present invention to provide a control device for a continuously variable transmission capable of ensuring the durability of a belt by preventing the belt from finally exceeding.

[0005]

According to a first aspect of the present invention, there is provided a control device for a continuously variable transmission which is wound around a pair of pulleys having variable groove widths. A continuously variable transmission mechanism that clamps a belt, and regulates the working fluid pressurized by the pump to a predetermined fluid pressure corresponding to the input load to the continuously variable transmission mechanism by a pressure regulating valve for the continuously variable transmission mechanism. A control device for a continuously variable transmission that supplies the continuously variable transmission mechanism, wherein a speed ratio detection unit that detects a speed ratio of the continuously variable transmission mechanism including the pair of pulleys, and an input rotation speed to the continuously variable transmission mechanism. an input rotational speed detecting means for detecting for the gear ratio depending on the gear ratio of the continuously variable transmission mechanism that is detected by the detection means, with respect to the fluid pressure supplied to the continuously variable transmission mechanism, to protect the belt set the maximum value of the fluid pressure, the input to this value
The smaller the input rotation speed detected by the rotation speed detection means, the smaller
A fluid pressure maximum value setting means for so that fence, control means for controlling the fluid pressure said supplied to the continuously variable transmission mechanism so that within the maximum value of the set fluid pressure in the fluid pressure maximum value setting means It is characterized by having.

[0006] The fluid pressure supplied to the continuously variable transmission mechanism used here is supplied to a cylinder chamber of a pulley so as to clamp a belt between two opposed cones, for example, referred to as the line pressure. Working fluid pressure. Similarly, the speed ratio of the continuously variable transmission mechanism composed of a pair of pulleys is not a ratio between the final output speed and the engine speed, but a speed ratio generally used in a transmission, that is, a speed reduction. In the present invention, the ratio is given by the radius ratio of the belt contact circular arc of the pulley, which is changed by changing the groove width, and in this case, it may be particularly called the pulley ratio. In addition, the maximum value of the fluid pressure supplied to the continuously variable transmission mechanism for protecting the belt is, for example, the maximum value of the fluid pressure supplied to ensure the durability of the belt. Is an upper limit value that does not cause. Therefore, even if the lateral load on the belt is the same as described above, the influence on the durability of the belt varies depending on the gear ratio and the input rotation speed, that is, the belt winding angle and the peripheral speed. The maximum value of the fluid pressure supplied to the step transmission mechanism is uniquely set. In the present invention, by controlling the final fluid pressure supplied to the continuously variable transmission mechanism, which is obtained by correcting the conventional centrifugal pressure or the like, to be within this maximum value, the durability of the belt is ensured. Protect.

According to a second aspect of the present invention, there is provided a control device for a continuously variable transmission , comprising: a pair of pulleys having variable groove widths;
Has a continuously variable transmission mechanism that clamps the belt
Depending on the input load to the continuously variable transmission mechanism
The pressure is adjusted to a predetermined fluid pressure by the pressure regulating valve for the continuously variable transmission mechanism.
The control unit for the continuously variable transmission supplied to the continuously variable
And the speed ratio of the continuously variable transmission mechanism including the pair of pulleys.
Speed ratio detecting means for detecting, and input to the continuously variable transmission mechanism
Input speed detecting means for detecting the speed, and the speed ratio detecting means.
Speed ratio and input rotation of the continuously variable transmission mechanism detected by the output means
Input speed to the continuously variable transmission mechanism detected by the speed detection means
Accordingly, for the fluid pressure supplied to the continuously variable transmission mechanism,
Set the maximum value of the fluid pressure to protect the belt
Fluid pressure maximum value setting means, and a fluid pressure maximum value setting means.
So that it is within the maximum value of the fluid pressure set in the step.
Control means for controlling the fluid pressure supplied to the step transmission mechanism.
The maximum value of the fluid pressure setting means is the largest when the speed ratio of the continuously variable transmission mechanism is 1.0 with respect to the equivalent input rotation speed to the continuously variable transmission mechanism, and The maximum value of the fluid pressure is set so as to decrease as the gear ratio of the mechanism is larger than 1.0 or smaller than 1.0.

In the present invention, consideration is given to the effect of the belt winding angle on the pulley on the durability of the belt. That is, when the speed ratio of the continuously variable transmission mechanism corresponding to the pulley ratio is 1.0, the belt winding angles of the respective pulleys are equal. On the other hand, when the speed ratio of the continuously variable transmission mechanism is greater than 1.0, the belt wrap angle of the input side pulley is reduced, and when the speed ratio of the continuously variable transmission mechanism is less than 1.0, the output side is reduced. In this case, the belt winding angle of the pulley becomes smaller, and in any case, the durability of the belt decreases. Therefore, in the present invention, for the same input rotational speed, the maximum value of the fluid pressure supplied to the continuously variable transmission mechanism is set to be maximum when the speed ratio of the continuously variable transmission mechanism is 1.0. Even when the gear ratio becomes larger or smaller, the belt is protected so as to ensure the durability of the belt by setting it to be gradually smaller with the change of the gear ratio.

In the control device for a continuously variable transmission according to a third aspect of the present invention, the fluid pressure maximum value setting means sets the maximum value of the fluid pressure to the same value as the input rotation speed to the continuously variable transmission mechanism. The maximum value of the fluid pressure so that the rate of decrease when the speed ratio of the continuously variable transmission mechanism is smaller than 1.0 is greater than the rate of decrease when the speed ratio of the stepped transmission mechanism is greater than 1.0. Is set.

In the present invention, the influence of the rotation speed of the pulley, that is, the peripheral speed of the belt, on the durability of the belt is considered. That is, the above-mentioned belt wrap angle is obtained when the speed ratio of the continuously variable transmission mechanism is larger or smaller than 1.0.
Only one of the pulleys will be smaller at a similar rate,
However, when the gear ratio becomes smaller than 1.0, the output rotation speed increases and the peripheral speed of the belt also increases. As the peripheral speed of the belt increases, the centrifugal force applied to the belt increases, so that even if the lateral load is the same, slipping and elongation of the belt easily occur, and the durability of the belt decreases. Therefore, in the present invention, it is the same that the case where the speed ratio of the continuously variable transmission mechanism is 1.0 is the maximum for the same input rotational speed, but the case where the speed ratio becomes smaller than 1.0. The rate of decrease of the maximum value of the supply fluid pressure is set to be greater than that when the gear ratio is greater than 1.0, thereby protecting the belt by ensuring the durability of the belt.
The control device for a continuously variable transmission according to claim 4 of the present invention.
The fluid pressure maximum value setting means includes a drive pulley and an input.
The gear ratio is larger than when the contact radius with the pulley is equal.
As the fluid pressure increases to protect the belt.
It is characterized in that the large value is set small. Ma
The control device for a continuously variable transmission according to claim 5 of the present invention.
The fluid pressure maximum value setting means includes a drive pulley and an input pulley.
Gear ratio is smaller than when the radius of contact with
The maximum of the fluid pressure to protect the belt
It is characterized in that the value is set small.

[0011]

As described above, according to the control apparatus for a continuously variable transmission according to the first aspect of the present invention, the belt is controlled in accordance with the gear ratio and the input rotation speed, that is, the belt winding angle and the peripheral speed. The maximum value of the fluid pressure supplied to the continuously variable transmission, which affects the durability of the motor, is controlled so that the final fluid pressure supplied to the continuously variable transmission, corrected for centrifugal pressure, etc., is within this maximum value. By doing so, the belt can be protected, for example, by ensuring its durability.

[0012] In the present invention, claim 2 or 4 or 5 of the present invention.
According to the control device for a continuously variable transmission according to the first aspect, the maximum value of the fluid pressure supplied to the continuously variable transmission mechanism is set to a maximum value when the speed ratio of the continuously variable transmission mechanism is 1.0, and the transmission is further shifted. The belt wrapping angle is reduced, that is, the belt endurance is increased by increasing the lateral load per unit area by setting the ratio to gradually decrease with the change of the gear ratio both when the ratio becomes smaller and larger than 1.0. Protect the belt by preventing the deterioration of the belt.

Further, according to the control device of the continuously variable transmission according to the third aspect of the present invention, the maximum value of the fluid pressure supplied to the continuously variable transmission mechanism is determined by setting the speed ratio of the continuously variable transmission mechanism to 1 .0 when the speed ratio becomes smaller than 1.0, and the rate of decrease of the maximum value of the supply fluid pressure to the continuously variable transmission mechanism when the speed ratio becomes smaller than 1.0. By setting a value larger than that of the belt, the belt is protected by preventing a decrease in the durability of the belt due to an increase in the peripheral speed of the belt, that is, an increase in the centrifugal force acting on the belt.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for a continuously variable transmission according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a continuously variable transmission and a control device thereof according to an embodiment of the present invention. First, the power transmission mechanism of this continuously variable transmission is described in Japanese Patent Application Laid-Open No. Hei 7-317895, previously proposed by the present applicant, except that the fluid coupling is changed to a torque converter. For the sake of equality, equivalent components will be briefly described with the same reference numerals. It should be noted that reference numeral 10 in FIG.
Denotes an engine, 12 denotes a torque converter, 15 denotes a forward / reverse switching mechanism, 29 denotes a belt-type continuously variable transmission mechanism, 56 denotes a differential device, and 66 and 68 denote left and right drive shafts for front wheels.

A throttle valve 19 that opens and closes in accordance with the amount of depression of an accelerator pedal by a driver is provided in the intake pipe 11 of the engine 10. The throttle valve 19 is provided with a throttle opening sensor 303 for detecting its opening (hereinafter also referred to as throttle opening) TVO. Further, the output shaft 10a of the engine 10, the rotational speed (hereinafter, referred to as engine speed) the engine speed sensor 301 for detecting the N _E is attached. The engine control unit 200 controls, for example, the fuel injection amount, its timing, ignition timing, and the like according to the engine load and the vehicle speed, so that the rotation state of the engine 10 is controlled to an optimum state according to the running state of the vehicle. You. Further, the detection signal of the throttle opening TVO detected by the throttle opening sensor 303 indicates that the throttle opening TVO is large and the depression amount of the accelerator pedal is large. Further, the engine speed sensor 30
1 may be configured to detect an engine rotation speed from an ignition ignition pulse of the engine.

The torque converter 12 connected to the output shaft 10a of the engine 10 has an existing lock-up mechanism. The left side of the lock-up facing shown is the fluid chamber 12a on the apply side, In other words, the space between the lock-up facing and the torque converter cover becomes the release-side fluid chamber 12b,
When the working fluid pressure to the release-side fluid chamber 12b increases, the lock-up state occurs. The output shaft of the torque converter 12, that is, the turbine output shaft 13, is provided with an input rotation speed sensor 305 for detecting a rotation speed (hereinafter simply referred to as input rotation speed) N _Pri to the continuously variable transmission mechanism 29. ing. In addition,
The forward / reverse switching mechanism 15, which will be described later, may control the so-called creep running force or the like when the accelerator pedal is not depressed, for example, by variably adjusting the engaging force of the forward clutch 40. Since the forward clutch 40 is completely engaged, the rotation speed of the turbine output shaft 13 is changed to the input rotation speed N _Pri to the continuously variable transmission mechanism.
Used as The working fluid supplied to the release-side fluid chamber 12b is drained through the apply-side fluid chamber 12a, and the drain of the working fluid supplied to the apply-side fluid chamber 12a is discharged from the release-side fluid chamber 12b. It is diverted to other cooling and lubrication systems. Therefore, the lock-up / unlock-up switching control is performed by switching the supply direction of the working fluid to the lock-up mechanism, not by switching the fluid path itself.

The forward / reverse switching mechanism 15 includes a planetary gear mechanism 17, a forward clutch 40, and a reverse brake 50. Among them, planetary gear mechanism 1
7 has a multi-stage pinion row, and a pinion carrier that supports these pinion rows is provided with a drive shaft 1.
4 is connected to the drive pulley 16 of the continuously variable transmission mechanism 29, and a sun gear is connected to the turbine rotating shaft 13. The pinion carrier can be fastened to the turbine rotating shaft 13 by a forward clutch 40, and the ring gear of the planetary gear mechanism 17 is connected to the reverse brake 5
0 indicates that it can be fastened to the stationary part. Therefore, when the forward clutch 40 is engaged by the working fluid pressure to the fluid chamber 40a, the drive shaft 14 and the turbine output shaft 13 rotate at the same speed in the same direction via the pinion carrier.
When the reverse brake 50 is engaged by the working fluid pressure to the fluid chamber 50a, the drive shaft rotates at a constant speed in the opposite direction to the turbine output shaft 13 via a multi-stage pinion row.

The drive pulley 16 constituting the continuously variable transmission mechanism 29 has a fixed cone 18 which rotates integrally with the drive shaft 14 and a V-shaped pulley groove which is disposed opposite to the fixed cone 18 and extends in the axial direction. And a movable movable cone 22. The movable cone 22 of the drive pulley 16 is formed with a cylinder chamber 20 to which a working fluid pressure is supplied to sandwich the belt 24 between the movable cone 22 and the fixed cone 18. Further, a driven pulley 26 around which the belt 24 is wound in a pair with the driving pulley 16 has a fixed cone 30 which rotates integrally with a driven shaft 28 and a V-shaped pulley groove which is disposed opposite to the fixed cone 30. A cylinder formed with a movable cone 34 which is movable in the axial direction, and to which the working fluid pressure is supplied in order to clamp the belt 24 between the movable cone 34 and the fixed cone 30. A chamber 32 is formed.

The belt-type continuously variable transmission mechanism 29 includes a pinion 108a meshing with the rack 182 and a stepping motor 1
08, and the rack 182 and the movable cone 22 of the movable pulley 16 are connected by a lever 178.
The rotation of the step motor 108 is controlled by a drive signal DS _{/ M} from a transmission control unit 300 described later, thereby moving the movable cone 22 of the drive pulley 16 and the movable cone 34 of the driven pulley 26 in the axial direction. By changing the radius of the contact position with the belt 24, the rotation ratio between the driving pulley 16 and the driven pulley 26, that is, the gear ratio (pulley ratio) can be changed. In the pulley ratio contact position radius change control, for example, as described above, in the present embodiment, the movable cone 22 of the drive pulley 16 is moved to change the groove width thereof, and thereby the movable cone 34 of the driven pulley 26 is changed.
Are automatically moved to change the groove width. This is because the belt 24 is a push-type belt that mainly transmits a driving force in the pressing direction as described above. The configuration of the push type belt is configured by arranging well-known elements in a longitudinal direction or a winding direction of the belt.

The drive gear 46 fixed to the driven shaft 28 meshes with the idler gear 48 on the idler shaft 52, and the pinion gear 54 provided on the idler shaft 52 meshes with the final gear 44. Front and left and right drive shafts 66 and 68 are connected to the gear 44 via a differential 56. A vehicle speed sensor 302 for detecting the vehicle speed V _SP is attached to the final output shaft.

Next, a fluid pressure control device for the continuously variable transmission will be described. In the fluid pressure control device, the working fluid in the reservoir 130 is sufficiently boosted by the pump 101 rotated by the rotational driving force of the engine 10 and supplied to the actuator unit 100. The configuration inside the actuator unit 100 is the same as that described in Japanese Patent Application Laid-Open No. Hei 7-317895 proposed earlier by the present applicant.
Detailed illustration and explanation are omitted.

The reference numeral 104 in FIG.
The clutch pressure P _CL is applied directly to the cylinder chamber 40a of the forward clutch 40 and the brake pressure P _BRK is applied to the cylinder chamber 50a of the reverse brake 50.
This is a manual valve for controlling the switching between. The select lever 103 detects the selected shift position and outputs a shift range signal S _RANGE corresponding to the detected shift position.
Is provided. Incidentally, this shift range signal S _RANGE corresponds to P, R, N, D, 2, according to the shift position of the actual vehicle.
The signal is equivalent to L.

Reference numeral 106 denotes a gear which is operated in accordance with the relative displacement between the step motor 108 and the movable cone 22 of the driving pulley 16, that is, the behavior of the lever 178, and mainly changes the speed, that is, the required gear ratio. The driving pulley 106 depends on the relative relationship with the groove width of the driving pulley 16.
This is a shift control valve that controls the working fluid pressure (line pressure) P _{L (Pri)} to the side.

Reference numeral 128 denotes a lock-up which is driven by a drive signal D _{L / U} from a transmission control unit 300, which will be described later, and which mainly controls lock-up / unlock-up of the torque converter 12 by a lock-up mechanism. This is a control duty valve. By the way, the lock-up control duty valve 128
Acts to lock up the torque converter 12 with a control signal with a large duty ratio and unlock with a control signal with a small duty ratio. Also, reference numeral 1
Reference numeral 29 denotes a clutch engagement control duty valve which is driven by a drive signal _DCL from a transmission control unit 300 described later and mainly controls the engagement force of the forward clutch 40 or the reverse brake 50. The clutch engagement control duty valve 129 acts to engage the forward clutch 40 or the reverse brake 50 with a control signal having a large duty ratio, and release the engagement with a control signal having a small duty ratio.

Reference numeral 120 denotes a driven pulley 26 (or a part of a driven pulley) which is driven by a drive signal _DPL from a transmission control unit 30 to be described later and holds the belt 24 as described above. 16)
A line pressure control duty valve 120 for controlling a working fluid pressure (hereinafter, this fluid pressure is also referred to as a line pressure) P _L. In the cited publication, the duty valve 120 is a modifier duty valve. This is because the output pressure from the duty valve 120 is
Once, it acts as a pilot pressure of a pilot pressure regulating valve called a pressure modifier valve, and as a result, the output pressure from the pressure modifier valve acts as a pilot pressure of the line pressure regulating valve, and the upstream side of the line pressure regulating valve. This is for adjusting the line pressure P _L formed in the above.
However, as it is apparent from this description, by controlling the duty ratio of the duty valve 120, but indirectly albeit, it is possible to control the line pressure P _L. This also, in the present embodiment, as shown in FIG. 2, except for the predetermined dead zone, with an increase of the duty ratio D / T _PL of the control signal or drive signal to the line pressure control duty valve 120 (Target) line pressure P
_{L (OR)} is assumed to increase linearly. Incidentally, when the output pressure from the pressure modifier valve is increased, the original pressure of the clutch pressure and the original pressure of the lock-up pressure of the torque converter can be simultaneously increased (different in slope and intercept). ing.

The transmission control unit 300
A microcomputer 310 as control means for outputting a control signal for controlling the continuously variable transmission mechanism 29 and the actuator unit 100 by executing, for example, an arithmetic process shown in FIG. The control circuit 310 includes drive circuits 311 to 314 that convert the control signal output from the drive signal to an actual actuator, that is, drive signals suitable for the step motor 108 and the duty valves 120, 128, and 129.

Among them, the microcomputer 31
0 denotes an input interface circuit 310a having, for example, an A / D conversion function, an arithmetic processing device 310b such as a microprocessor, and a storage device 310c such as a ROM and a RAM.
And an output interface circuit 310d having a D / A conversion function, for example. The microcomputer 310 obtains the rotation angle of the step motor 108 that controls the actual gear ratio by performing the arithmetic processing described in, for example, the above-mentioned Japanese Patent Application Laid-Open No. 7-317895, and performs pulse control to achieve the rotation angle. A line pressure control duty valve 1 necessary to output the signal S _{S / M} or to obtain the optimum line pressure P _L for clamping the belt 24 is required.
A duty ratio D / T _PL of 20 is calculated, and a line pressure control signal S _PL corresponding to the duty ratio D / T _PL of the line pressure control is calculated.
Or the optimal working fluid pressure (hereinafter simply referred to as torque converter pressure) P _{T / C} for controlling the lock-up / unlock-up control of the lock-up mechanism of the torque converter 12 is obtained and achieved. The duty ratio D / of the lock-up control duty valve 128
Calculate T _{L / U} and calculate its lock-up control duty ratio D
/ T _{L / U} according to the output of a lock-up control signal S _{L / U} or, for example, an optimal working fluid pressure (hereinafter simply referred to as clutch pressure) for creep running of the vehicle when the accelerator pedal is not depressed. also referred to as) seeking P _CL, the clutch engagement control duty valve required to achieve it 129
Of calculating the duty ratio D / T _CL, a clutch engagement control signal S corresponding to the clutch pressure control duty ratio D / T _CL
Output _CL .

The drive circuit 311 converts the pulse control signal S _{S / M} into a drive signal D _{S / M} suitable for the step motor 108, and the drive circuit 312 outputs the line pressure control signal S _PL
To the drive signal D _PL suitable for the line pressure control duty valve 120, and the drive circuit 313 outputs the lock-up control signal S
_{L / U} is used as the drive signal D _{L / U} suitable for the lock-up control duty valve 128, and the drive circuit 314 uses the clutch engagement control signal S _CL as the clutch engagement control duty valve 129.
Are converted into drive signals _DCL suitable for the output, and output.

For example, the form of the control signal or the pulse control signal corresponding to the duty ratio already satisfies the desired duty ratio and the number of pulses, and the driving circuits 311 to 31
Reference numeral 4 merely performs electrical processing such as, for example, amplifying the signal, but does not process the signal itself.

The engine control unit 200 also has its own microcomputer, and communicates with the microcomputer 310 of the transmission control unit 300 to operate the engine and the transmission according to the running state of the vehicle. It is configured to control to an optimum state.

Next, the schematic structure of the entire shift control according to the present embodiment will be described in accordance with the general flow calculation processing shown in FIG.
This calculation process is basically a simple summary of the shift control described in JP-A-7-317895 in a state where the D range is selected and there is no request from the engine control unit side. Yes, the details will be referred to the publication, and only the outline of the general flow will be described here. This calculation process is executed as a timer interrupt process at every predetermined sampling time (for example, 10 msec) ΔT. Note that, in the subsequent arithmetic processing, any step for communication is not particularly provided, but a necessary program or map or necessary data in the arithmetic processing device 310b is read from the storage device 310c as needed.
Conversely, the data calculated by the arithmetic processing unit 310b is updated and stored in the storage device 310c as needed.

In this calculation process, first, in step S1,
The vehicle speed V from the vehicle speed sensor 302 _SP,Engine RPM
Engine speed N from sensor 301_E, Input rotation speed
Input speed N from sensor 305_Pri, Throttle opening
Throttle opening TVO from the sensor 303 and the inhibitor
Range signal S from the data switch 304_RANGERead
Put in.

[0034] and then proceeds to step S2, according to each individual arithmetic process, the vehicle speed V _SP, and calculates the current transmission ratio C _P from the input rotation speed N _Pri. Specifically, the output speed N _Sec of the continuously variable transmission mechanism 29 is obtained by dividing the vehicle speed V _SP proportional to the final output shaft rotation speed by the so-called final reduction ratio n from the continuously variable transmission mechanism 29 to the final output shaft. Is obtained, the current gear ratio C _P can be obtained by calculating the ratio of the input rotation speed N _Pri to this.

Next, the process proceeds to step S3, where the throttle opening TV is set in accordance with individual calculation processing such as control map search.
Of O, it calculates the engine torque T _E from the engine speed N _E. Specifically, as shown in FIG. 4, for example, the throttle opening TVO is used as a parameter and the engine speed N _E
Calculating a current engine torque T _E from the output characteristic diagram of the engine torque T _E corresponding to.

[0036] Next, the process proceeds to step S4, performs control of the line pressure P _L in accordance with the arithmetic processing of Fig. 7 to be described later.
Next, the process proceeds to step S5, in which lock-up control is performed in accordance with individual calculation processing. Specifically, for example, FIG.
The lock-up vehicle speed V _ON and the unlock-up vehicle speed V _OFF according to the vehicle speed V _SP and the throttle opening TVO are set in principle. If the vehicle speed V _SP is higher than the lock-up vehicle speed V _ON, lock-up and unlock-up are performed in principle. vehicle speed V _OFF will be created outputs a control signal S _{L / U} as if the lockup less, especially when transition to the lock-up side, the engine rotational speed N _E and the input rotational speed N _Pri at that time, i.e., When the difference value from the turbine output shaft rotation speed is large, the duty ratio D / _{TL / U} is increased with a relatively large gain corresponding to the difference value, and the difference value between the two becomes small, ie, lock-up. When the user feels a little, the duty ratio D / T _{L / U} is increased by a relatively small predetermined value to reduce the shock at the time of complete lock-up transition.

Next, the operation proceeds to step S6, where the attained gear ratio _CD is calculated according to individual calculation processing such as control map search. The goal transmission ratio C _D achieves the current engine speed N _E and a vehicle speed V _SP and the throttle opening TVO, the most ideal speed ratio of the continuously variable transmission mechanism 29, in particular 6 as shown in, if set speed ratio C, 3 person coincide perfectly, while satisfying the vehicle speed V _SP and the engine speed N _E at that time, the amount of depression of the accelerator pedal by the driver, i.e. the throttle opening Acceleration corresponding to TVO can be obtained. Here, for example, FIG. 6 reaches the gear ratio C _D
Assuming that the control map is used to set the speed, a straight line having a constant slope passing through the origin becomes a certain speed change ratio.For example, a straight line having the largest slope in the entire region of the speed change pattern has the lowest speed reduction ratio of the entire vehicle. Large, that is, the maximum gear ratio C
On the other hand, a straight line which is _Lo and has the smallest inclination may be considered to have the smallest reduction ratio of the entire vehicle, that is, the D range minimum speed ratio _CDHi .

Next, the routine proceeds to step S7, where the target gear ratio C _R is calculated according to individual arithmetic processing. Specifically, in principle the goal transmission ratio C _D is greater if the downshift direction from the current transmission ratio C _P, if smaller upshift direction, for example, the fastest shift speed dC current transmission ratio C _{P R} / the gear ratio after dt or smallest time constant τ predetermined sampling time and shift with ΔT set as the target speed ratio C _R. However, when the throttle opening TVO changes from the state close to the fully open state to the closing direction, that is, when the accelerator pedal is released, the shift speed dC _R / dt is slightly reduced or the time constant τ is slightly increased. When the accelerator pedal is released, the speed of change of the throttle opening in the closing direction is fast and the amount of change of the throttle opening in the closing direction is large. In other words, the shift speed dC _R / dt is further reduced or the time constant τ is increased. The speed ratios are further increased, and the target speed ratios _CR are set respectively.

Next, the process proceeds to step S8, where individual calculation is performed.
The clutch engagement control is performed according to the processing. In particular,
Vehicle speed V in principle_SPIs greater than the creep control threshold.
Fasten latch 40, vehicle speed V_SPIs below the creep control threshold
And the throttle opening TVO is a fully closed threshold value for creep control.
If so, the control signal S is issued to cancel the fastening._CLCreate and output
But the vehicle speed V_SPIs less than the creep control threshold and the slot
If the opening TVO is less than the fully closed threshold,
Engine rotation speed N_EAnd input rotation speed N_Pri, That is, the turbine
The gain is inversely proportional to the difference between the
Tee ratio D / T _CLBy setting the
Engage clutch when vehicle is easy to creep due to sound
Reduce the force and engage the clutch when creeping is difficult
I try to strengthen my strength.

Next, the flow shifts to step S9, where the gear ratio control is performed according to the individual arithmetic processing, and then the process returns to the main program. Specifically, the set target gear ratio C
_{For R} , the total number of pulses and the number of pulses are set to the unit time value for shifting at the shift speed dC _R / dt or time constant τ at that time, and the pulse control signal S _{S / M} satisfying both of them is set. Is generated and output.

Next, the arithmetic processing for changing the control threshold executed in step S4 of the arithmetic processing of FIG. 3 in the present embodiment will be described with reference to FIG. In this calculation processing, first, in step S401, the torque converter input / output speed ratio N _E / N is determined according to individual calculation processing such as control map search.
_The torque ratio t is calculated from _Pri . Specifically, the input / output speed ratio N _E / N _Pri is calculated by dividing the engine speed N _E by the input speed N _Pri , that is, the turbine output shaft speed. As shown in FIG. the torque converter input and output speed ratio N _E / N _Pri torque converter from (torque converter in the drawing) region, i.e. as to discriminate whether the torque amplification region or a lockup region, according to the torque converter input and output speed ratio N _E / N _Pri if torque converter region The calculated torque ratio t is obtained.

[0042] and then proceeds to step S402, wherein by multiplying the torque ratio t on the engine torque T _E to calculate the input torque T _Pri, then the process proceeds to step S403,
According to the control map of FIG. 9, the reference line pressure P _L0 is calculated using the input torque T _Pri . The control map of FIG. 9 is a setting map of a reference line pressure P _L0 corresponding to the input torque T _Pri the parameters to and current transmission ratio C _P. As described above, the line pressure P _L from a side load to the belt 24, from the surface of the belt durability, or the line pressure P _L in terms of energy loss is small is desirable.
However, since torque to be transmitted is applied to the belt 24, the belt 24 must be pinched by a pulley so that the belt does not slip. The torque is defined as the transmission ratio C _P is larger and / or the input torque T _Pri. since the larger the larger, it is necessary to increase the line pressure P _L to increase the belt clamping force by that much. The reference line pressure P _L0 is set based on only the gear ratio C _P and the input torque T _Pri . Of course, the reference line pressure P _L0 is set to be much smaller than a region that directly affects the durability of the belt.

Next, the flow shifts to step S404 to divide the vehicle speed _VSP by the final reduction ratio n as described above to obtain the output rotation speed N.
_Sec is calculated, and the process then proceeds to step S405 to multiply the square value (N _Sec ) ² of the output rotation speed by a predetermined coefficient k to calculate the centrifugal pressure P _L1 of the output side, that is, the driven pulley. As described above, the centrifugal pressure P _L1 indicates that the working fluid in the cylinder chamber 32 of the driven pulley 26 is pressed against the outer peripheral side by the centrifugal force.
The working fluid pressure on the outer peripheral side inside increases, and this is the line pressure P _L
Shows the increase in working fluid pressure acting synergistically with. Therefore,
This centrifugal pressure P _L1 is proportional to the peripheral speed, that is, the square value (N _Sec ) ² of the output rotation speed, similarly to a normal centrifugal force, and is multiplied by a proportional coefficient k that takes into account the specific gravity and viscosity of the working fluid. Is calculated.

Next, the flow shifts to step S406, where the basic
Quasi line pressure P_L0And centrifugal pressure P_L1Line pressure P from the sum of
_LDThen, the process proceeds to step S407, and FIG.
From the control map of 0, the maximum line pressure P_LMAXCalculate and set
You. The control map shown in FIG._PAnd input times
Number of turns N_PriLine pressure P according to_LMAXIn the settings map
The characteristic curve shown is the maximum line pressure P_LMAXContinuous song
Line and the equivalent gear ratio C_PIs roughly entered.
Power speed N_PriIs larger, the maximum line pressure P_LMAXIs small
No. In addition, the equivalent input rotation speed N_PriFor the gear ratio
C_P(Pulley ratio) is "1.0",
Belt contact radius of the rib 16 and belt contact of the driven pulley 26
Maximum line pressure P when radius is equal_LMAXIs the largest
Gear ratio C _PIs greater than "1.0"
Even if it becomes smaller, the maximum line pressure P_LMAXIs small
Become. Also, the gear ratio C_PIs greater than "1.0"
The maximum line pressure P_LMAX
The rate of decrease is large. See below for the reasons for these settings.
The operation of the step will be described in detail.

[0045] Next, the process proceeds to step S408, the required line pressure P _LD is equal to or in the maximum line pressure P _LMAX above, the required line pressure P _LD is the maximum line pressure P
If it is equal to or greater than _{LMAX, the process proceeds} to step S409, otherwise, the process proceeds to step S410. In step S409, the maximum line pressure P _LMAX is set to the attained line pressure P _LR , and then the flow shifts to step S411. In step S410, the required line pressure P _LD is set to the attained line pressure P _LR , and then the process proceeds to step S411.

In step S411, the arrival line
Pressure P_LRCentrifugal pressure P_L1To the target line pressure P_L0RTo
Then, the process proceeds to step S412,
From this control map, the target line pressure P_L0RAchieve
Pressure control duty ratio D / T_PLCalculate and set
Next, the processing shifts to step S413 to perform individual calculation processing.
Therefore, the line pressure control duty ratio D / T_PLAccording to
Line pressure control signal S _PLAfter generating and outputting
The process proceeds to Step S5 of the arithmetic processing of. The line pressure
Control duty ratio D / T_PLControl map for existing dues
The detailed description is omitted because it is only necessary to apply the duty ratio control.
Abbreviate. Also, the line pressure control duty ratio D / T_PLIn response
Line pressure control signal S_PLFor the creation of the existing P
What is necessary is to apply WM (Pulse Width Modulation) control
Therefore, the detailed description is omitted.

Next, the operation of this embodiment will be described. The outline of the shift control is the same as that described in the above-mentioned Japanese Patent Application Laid-Open No. Hei 7-317895, and is omitted here. The operation of the arithmetic processing will be described in detail.
In this calculation processing, steps S401 to S4
At 03, the reference line pressure P _L0 according to the input torque T _Pri to the continuously variable transmission mechanism 29 is set. This reference line pressure P
_{Since L0} is originally the minimum pressure at which the belt does not slip due to the torque to be transmitted, there is no hindrance to the durability of the belt. However, following step S404, step S
The centrifugal pressure P _L1 calculated in 405 is the output rotation speed N
_Since it is proportional to the square value of _Sec, the required line pressure P _LD to which this is added in step S406 becomes a very large value in some cases, which may affect the durability of the belt. On the other hand, although the centrifugal pressure P _L1 is definitely generated, it is not controlled, that is, it does not become an accurate value. Therefore, it is not possible to set the reference line pressure P _L0 to an accurate small value in anticipation of that amount. Can not. Therefore, in the present embodiment, the maximum line pressure P _LMAX which is considered to affect the durability of the belt is set, and if the required line pressure P _LD does not exceed this, the process proceeds from step S408 to step S410 to request the belt. Line pressure P _LD is reached line pressure P
Set to _LR , but the required line pressure P _LD is equal to the maximum line pressure P
If it is not less than _{LMAX, the process proceeds} to step S409 to set the maximum line pressure P _LMAX to the attained line pressure P _LR, and at the next step S411, a value obtained by subtracting the centrifugal pressure P _L1 from the attained line pressure P _LR. a target line pressure P _L0R that should manage, subsequent step S412, in step S413, is created output line pressure control signal S _PL to achieve this target line pressure P _L0R.

[0048] Here, although the maximum line pressure P _LMAX is set, for the same transmission ratio C _P, as described above, schematically input rotation speed N _Pri maximum line pressure greater the P _LMAX Is small. This is generally the input rotation speed N _Pri
Is larger, the peripheral speed of the belt is faster, and therefore the centrifugal force applied to the belt is larger. On the other hand, the belt groove of each of the pulleys 16 and 26 has a V-shape in which the outer peripheral side is wider, so that If the line pressure, which is the lateral load on the belt, is large under the condition of high centrifugal force, the belt will slip and elongate, and the durability will decrease. _Therefore , the maximum line pressure P _LMAX decreases as the input rotation speed N _Pri increases. Must.

For the same input rotational speed N _Pri , when the speed ratio C _P (pulley ratio) is “1.0”, that is, the belt contact radius of the driving pulley 16 and the belt contact radius of the driven pulley 26. DOO maximum line pressure P _LMAX is highest at equal, even larger than the speed ratio C _P is "1.0", even smaller than that, both the maximum line pressure P _LMAX
Becomes smaller. This is also due to the fact that this type of belt is a push belt in which elements are arranged as described above. That is, as shown in FIG.
The angles at which the belt 24 is wound around the belts 6 and 26 are the winding angles θ _Pri and θ _{Se c} , and the contact radii at that time are r _Pri and r
Defining the _Sec, contact radius ratio (r _Sec / r _Pri) even represented by the gear ratio C _P are "1.0" wrap angle theta _Pri is either of the pulley when, theta _Sec also equal. However, the gear ratio C _P are "1.0" from the larger the winding angle theta _Pri of the drive pulley 16 side becomes small, the gear ratio wrap angle of the C _P is "1.0" smaller than the driven pulley 26 side θ _Sec decreases. When the winding angle θ is reduced as described above, the length of the contact line between the belt 24 and each of the pulleys 16 and 26 is reduced, and the number of elements in contact with the pulleys 16 and 26 is also reduced. side loads of a single element even is taking lateral load is increased, thus the durability of the belt is decreased, the maximum line pressure P _LMAX is also the gear ratio C _P becomes larger than "1.0" Even if it gets smaller, it must be set smaller.

For an equivalent input rotational speed N _Pri ,
Than when the gear ratio C _P is greater than "1.0" is also, who when made smaller, a large reduction ratio of the maximum line pressure P _LMAX. This is because, for an equivalent input rotational speed N _Pri , a reduction in the gear ratio C _P results in an increase in the vehicle speed V _SP , and therefore, as the gear ratio C _P decreases, the output rotational speed N _Sec increases. As a result, the belt peripheral speed increases. Then, as described above, the centrifugal force applied to the belt increases, and the durability decreases.
_LMAX must be reduced as the input rotation speed N _Pri increases.

Therefore, if the ultimate line pressure P _LR can be regulated by the maximum line pressure P _LMAX set in this way, at least the durability of the belt does not decrease. Although the final target line pressure P _L0R may be set lower than the reference line pressure P _L0 , the value of the centrifugal pressure P _L1 is uncertain as described above,
Since the pressure is surely and largely generated, the sum of the centrifugal pressure P _L1 and the target line pressure P _L0R does not become smaller than the reference line pressure P _L0 , so that the belt does not slip.

As described above, the line pressure duty valve 12
0 constitutes the pressure regulating valve for the continuously variable transmission mechanism of the present invention. Similarly, the input speed sensor 305 and the vehicle speed sensor 302
Steps S1 and S2 of the calculation processing of FIG.
And step S1 of the calculation processing of FIG. 3 constitutes the input rotation speed detecting means, and step S407 of the calculation processing of FIG. 7 executed in step S4 of the calculation processing of FIG. 3 constitutes the fluid pressure maximum value setting means, The entire arithmetic processing of FIG. 7 executed in step S4 of the arithmetic processing of FIG. 3 constitutes the control means.

In each of the above embodiments, only the control unit constructed by a microcomputer has been described in detail. However, the present invention is not limited to this.
It goes without saying that electronic circuits such as arithmetic circuits may be combined.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a continuously variable transmission and a control device thereof.

FIG. 2 is a control map for setting a duty ratio from a target line pressure to a line pressure control duty valve.

FIG. 3 is a flowchart illustrating an example of a calculation process executed by the transmission control unit of FIG. 1;

FIG. 4 is a control map for setting an engine torque from an engine speed using a throttle opening as a parameter.

FIG. 5 is a control map for setting a lockup vehicle speed and an unlockup vehicle speed from a vehicle speed and a throttle opening.

FIG. 6 is a control map for setting a gear ratio from a vehicle speed using a throttle opening as a parameter.

FIG. 7 is a flowchart of a minor program executed in the calculation processing of FIG. 3;

FIG. 8 is a control map for setting a torque ratio from a torque converter input / output speed ratio.

FIG. 9 is a control map for setting a reference line pressure from a gear ratio using an input torque as a parameter.

FIG. 10 is a control map for setting a maximum line pressure from a gear ratio and an input rotation speed.

FIG. 11 is an explanatory diagram of a belt winding angle.

[Description of Signs] 10 is an engine 12 is a torque converter 16 is a drive pulley 19 is a throttle valve 20 is a cylinder chamber 24 is a belt 26 is a driven pulley 29 is a continuously variable transmission mechanism 32 is a cylinder chamber 108 is a step motor 120 is a line pressure control Duty valve 128 is a lock-up control duty valve 129 is a clutch engagement control pressure switching valve 200 is an engine control unit 300 is a transmission control unit 301 is an engine speed sensor 302 is a vehicle speed sensor 303 is a throttle opening sensor 304 is an inhibitor Switch 305 is input speed sensor 310 is microcomputer

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI F16H 63:06 F16H 63:06 (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 9/00 F16H 59/00 -63/48

Claims (5)

(57) [Claims] 1. A continuously variable transmission mechanism for sandwiching a belt to be wound between a pair of pulleys having variable groove widths, and a working fluid pressurized by a pump corresponding to an input load to the continuously variable transmission mechanism. A control device for a continuously variable transmission that regulates a predetermined fluid pressure with a pressure regulating valve for a continuously variable transmission mechanism and supplies the pressure to the continuously variable transmission mechanism, and detects a speed ratio of the continuously variable transmission mechanism including the pair of pulleys. a speed ratio detection means for the input rotation speed detecting means for detecting an input speed of the continuously variable transmission mechanism, depending on the gear ratio of the continuously variable transmission detected by the gear ratio detecting means, said Mu relative to the fluid pressure supplied to the variable transmission, sets the maximum value of the fluid pressure for protecting the belt, said the value
The larger the input rotation speed detected by the input rotation speed
Fluid pressure maximum value setting means for reducing the pressure, and control for controlling the fluid pressure supplied to the continuously variable transmission mechanism so as to be within the maximum value of the fluid pressure set by the fluid pressure maximum value setting means. And a control device for the continuously variable transmission. 2. A pair of pulleys having a variable groove width and wound by a pair of pulleys.
With a continuously variable transmission mechanism that clamps the belt
Where the applied working fluid is applied to the input load to the continuously variable transmission mechanism.
Adjust the pressure to a constant fluid pressure with the pressure control valve for the continuously variable transmission
In the control device of the continuously variable transmission that supplies the transmission mechanism,
The speed ratio of the continuously variable transmission mechanism including the pair of pulleys is detected.
Speed ratio detecting means, and an input rotation speed to the continuously variable transmission mechanism.
Input speed detecting means for detecting the gear ratio, and the speed ratio detecting means
Speed ratio and input speed detection of the continuously variable transmission mechanism detected by
According to the input speed to the continuously variable transmission mechanism detected by the means
With respect to the fluid pressure supplied to the continuously variable transmission mechanism,
Set the maximum value of the fluid pressure to protect the belt
The fluid pressure maximum value setting means and the fluid pressure maximum value setting means
Steplessly changing the pressure so that it is within the maximum value of the set fluid pressure.
Control means for controlling the fluid pressure supplied to the speed mechanism.
The fluid pressure maximum value setting means, when the speed ratio of the continuously variable transmission mechanism is 1.0 with respect to the equivalent input rotation speed to the continuously variable transmission mechanism, A control device for a continuously variable transmission, wherein the maximum value of the fluid pressure is set so as to become smaller as the gear ratio of the mechanism is larger than 1.0 or smaller than 1.0. 3. The fluid pressure maximum value setting means, for an equivalent input rotational speed to the continuously variable transmission mechanism, determines a reduction rate when the speed ratio of the continuously variable transmission mechanism is greater than 1.0. 3. The continuously variable transmission according to claim 2, wherein the maximum value of the fluid pressure is set such that a decrease ratio when the speed ratio of the continuously variable transmission mechanism becomes smaller than 1.0 becomes large. Control device. 4. The drive pressure maximum value setting means includes a drive pool.
The gear ratio is higher than when the contact radius of the
As it gets larger, the flow to protect the belt
The maximum value of body pressure is set small.
2. The control device for a continuously variable transmission according to claim 1. 5. The drive pressure maximum value setting means includes a drive pool.
The gear ratio is higher than when the contact radius of the
As it gets smaller, the flow to protect the belt
The maximum value of body pressure is set small.
5. The control device for a continuously variable transmission according to 1 or 4.