JPH09217806A - Toroidal type continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ideal operating performance by compensating a target gear ratio according to a torque deviation between a target input torque and an actual input torque in a toroidal type continuously variable transmission which is provided with a pair of power rollers generating a gear ratio according to a change in inclination angle relative to input and output disks. SOLUTION: A toroidal type continuously variable transmission detects the hydraulic pressure of oil in the cylinder chambers 8a and 8b of a hydroulic cylinder which displaces a trunnion 4 in an inclination axis direction, corrects a target gear ratio by a controller 25 based on the detected values, and operates a spool valve 10 so as to change the position of the trunnion 4 in inclination axis direction for the control of the gear ratio. Namely, a controller 25 detects a pressure difference with each hydraulic pressure acting on the cylinder chambers 8a and 8b, and calculates an actual input torque as a function of the pressure difference and gear ratio. Then a difference with a target input torque is obtained based on an output from an accelerator pedal sensor 20 and, when the difference thus obtained is negative, the target gear ratio is compensated to the speed increasing side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention continuously changes the rotation of an input disk in response to changes in the tilting angle with respect to the input disk and the output disk, and the output disk to the output disk. The present invention relates to a toroidal-type continuously variable transmission including a transmission unit including a pair of power rollers for transmission.

[0002]

2. Description of the Related Art As a toroidal type continuously variable transmission mounted on an automobile, a double cavity type toroidal type continuously variable transmission in which two transmission units are arranged on the same shaft is generally used. The toroidal type continuously variable transmission generally includes an input shaft to which an engine output is input, a pair of input discs rotatably supported with respect to the input shaft, and input shafts that are arranged to face each of the input discs. A pair of output discs rotatably supported with respect to each other, a pair of opposing input discs, and a tiltable power roller arranged between the input discs and transmitting rotation from the input discs to the output discs, a pair of opposing discs. Connecting member for integrally connecting the output discs of the above, a pair of flange portions provided on the input shaft and the input disc, which are arranged between the input discs and act on each of the input discs to press the power roller according to the magnitude of the input torque. It has a pressing means for changing the force, and by tilting the power roller, the rotation of the input disk is changed to the output disk according to the tilt angle. It is configured to shift to be transmitted to the stage.

FIG. 3 shows the toroidal type continuously variable transmission in a form showing only a transmission unit on the engine side of a pair of transmission units. The output of the engine E is transmitted to the input disc 3 of the transmission unit 1 via the input shaft 21 and the loading cam 22, is transmitted to the power roller 2 and the output disc 23 in this order, and is output to the output shaft 24. Shift control of the toroidal type continuously variable transmission is performed by displacing the trunnion 4 supporting the power roller 2 in the tilt axis direction extending in the direction perpendicular to the plane of the drawing. That is, when the trunnion 4 is displaced in the tilt axis direction, a tilting force around the tilt axis is generated from the input / output disks 3 and 23 with respect to the power roller 2. When the power roller 2 tilts around the tilt axis, the contact rotation radius ratio r ₁ / r _{2 of} the input / output disks 3 and 23 with the power roller 2 changes, and the rotation speed between the input / output shafts 22 and 24 changes. The ratio, that is, the gear ratio can be changed. The displacement of the trunnion 4 in the tilt axis direction is controlled by the hydraulic pressures Pup and Pdown supplied to the hydraulic cylinder and applied to the piston 7 (see FIGS. 1 and 4) fixed to the trunnion 4 in the tilt axis direction. To be done. A pair of transmission units 1 on the input / output shafts 22 and 24
For the toroidal type continuously variable transmission in which is arranged, the same gear shifting operation as described above can be further obtained, and a wide range of gear ratio can be obtained.

Various types of toroidal type continuously variable transmissions such as those described above have been conventionally used (Japanese Patent Application Laid-Open No. 7-151218, Japanese Patent Application No. 6-1339 filed by the present applicant).
No. 09) is known, and for example, a toroidal type continuously variable transmission as shown in FIG. 4 is known. FIG.
In order to simplify the explanation, the configuration for performing the shift control for one transmission unit has been described in the above, but in the case of a double-cavity toroidal type continuously variable transmission, the hydraulic pressure is the hydraulic pressure of the other transmission unit. Since it only has to be configured to be able to supply to the cylinder, the description of the structure of the other transmission unit and the supply of hydraulic pressure to the hydraulic cylinder will be omitted.

In the structure of the transmission unit 1 of the toroidal type continuously variable transmission shown in FIG. 4, the same components as those shown in FIG. 3 are designated by the same reference numerals. The pair of power rollers 2 in the transmission unit 1 are arranged so as to be opposed to each other so as to be sandwiched between an input disk 3 and an output disk (not shown) which are arranged opposite to each other. The power roller 2 is supported by a support member called a trunnion 4 via a rotatable eccentric shaft 5. The trunnion 4 is supported so as to be rotatable and axially movable with respect to a transmission casing (not shown). That is, the trunnion 4 has the tilting shaft 6, is movable in the axial direction of the tilting shaft 6, and can rotate about the tilting shaft 6. A piston 7 is fixed to the tilt shaft 6 of the trunnion 4, and the piston 7 is slidable in a hydraulic cylinder 8 formed in the transmission casing. In the hydraulic cylinder 8, cylinder chambers 8a, 8 partitioned by a piston 7 are provided.
b is formed.

Cylinder chambers 8a and 8b of the hydraulic cylinder 8 communicate with the spool valve 10 through pipe lines 9a and 9b. The spool 11 arranged in the spool valve 10 is held in a neutral position by springs 12 arranged at both ends in the axial direction. The spool valve 10 has a Sa port formed at one end and an Sb port formed at the other end, a pilot pressure is supplied to the Sa port via a solenoid valve 13a, and a pilot pressure is supplied to the Sb port via a solenoid valve 13b. Is supplied. The spool valve 10 is connected to a P port which is connected to pilot pressure, an A port which is connected to the cylinder chamber 8a through a pipe line 9a, a B port which is connected to the cylinder chamber 8b through a pipe line 9b, and a drain. It is equipped with a T port that can be used. Solenoid valves 13a, 13b
Are configured to operate in response to a control signal output from the controller 14.

A precess cam 1 is provided at the tip of one tilt shaft 6.
5 is connected, one end of a lever 16 pivotally connected at the center thereof contacts the precess cam 15, and the other end of the lever 16 is connected to a potentiometer 17. Potentiometer 17
Detects the axial displacement and tilt angle of the tilting shaft 6 of the trunnion 4 as a combined displacement amount, and outputs a detection signal to the controller 14
To enter. In addition to the combined displacement amount, the controller 14 receives information for controlling a shift from a shift information detecting device 30 including a vehicle speed sensor, that is, an output shaft rotation sensor 18, an engine rotation sensor 19, an accelerator pedal depression amount 20, and the like. . A shift information signal such as a vehicle speed, an engine speed, a fuel supply amount corresponding to an accelerator pedal depression amount detected by these sensors is input to the controller 14.

In the toroidal type continuously variable transmission, the trunnion 4 is tilted from the neutral position (the position where the rotation center axis of the power roller 2 intersects with the rotation center axes of the input disc 3 and the output disc 23) to one of the positions. When the shaft 6 is displaced in the axial direction, the trunnion 4 is tilted around the tilting shaft 6 in a direction and at a speed according to the direction and the amount of displacement, and the property that the gear shifting is performed by this tilting is used. . Controller 14
Is a hydraulic pressure Sa that displaces the trunnion 4 in the tilt axis direction,
The solenoid valve 1 is adjusted so that the differential pressure of Sb is proportional to the deviation between the target gear ratio and the actual gear ratio (hereinafter referred to as the actual gear ratio).
The output signals to 3a and 13b are controlled.

Next, the operation of the toroidal type continuously variable transmission will be described. First, the controller 14 calculates the target gear ratio based on the detected values relating to various gear shift information detected by the various sensors. . That is, the target gear ratio is detected by the various sensors described above, and the output shaft rotation stored in the controller 14 is based on the data of the output shaft rotation speed, the engine rotation speed, the throttle opening, etc. which are input to the controller 14. It is determined from a map table that corresponds to a combination of the number, the engine speed, the throttle opening, and the like. Further, the controller 14 calculates the actual gear ratio from the combined displacement amount of the tilt angle of the trunnion 4 detected by the recess cam 15 and the potentiometer 17 and the tilt axis direction,
A gear ratio deviation between the target gear ratio and the actual gear ratio is calculated. Since the combined displacement amount of the potentiometer 17 when the power roller 2 is in the neutral position and the gear ratio is 1 is used as a reference, calculate the actual gear ratio from the tilt angle when the power roller 2 is in the neutral position. You can Further, the controller 14 sets a target displacement of the trunnion 4 in accordance with the gear ratio deviation, and adds the control signal corresponding to the neutral position of the spool valve to the solenoid valves 13a and 13b and the control signal corresponding to the gear ratio deviation. Output a signal.

Along with this, the solenoid valves 13a, 13
Oil pressures Sa and Sb are supplied to both ends of the spool valve 10 from b. The spool valve 10 includes solenoid valves 13a and 13b.
The hydraulic pressures Sa, Sb supplied from the spring and the force of the spring 12 are displaced to a balanced position. At that time, when the relationship between the hydraulic pressures Sa and Sb supplied to the spool valve 10 is Sa> Sb, the spool 11 shifts to the left side in FIG. 4, and the pipe line 9a moves to the pressure source P via the P port. To the drain through the T port, and the conduit 9b communicates with the conduit 9a.
Pressure Pa becomes larger than the pressure Pb of the pipeline 9b (P
a> Pb). As a result, the piston 7 moves due to the pressure difference between the cylinder chambers 8a and 8b, the left trunnion 4 in FIG. 4 is displaced upward in the tilt axis direction, and the right trunnion 4 is displaced downward in the tilt axis direction. Along with this displacement, each trunnion 4 tilts about the tilt axis 6 and the power roller 2
Receives a force from the input disk 3 and the output disk 23 in the direction of the velocity vector and starts tilting to start the gear shifting operation.

In the toroidal continuously variable transmission, the controller 14 performs feedback control so that the actual gear ratio approaches the target gear ratio. That is, the target displacement of the trunnion 4 approaches zero as the actual gear ratio approaches the target gear ratio, and the target displacement of the trunnion 4 becomes zero when the actual gear ratio matches the target gear ratio. At this time, spool valve 1
The pressures applied to both ends of 0 become equal (Sa = Sb), the spool 11 of the spool valve 10 returns to the neutral position, the spool valve 10 is closed, the supply of hydraulic pressure to the hydraulic cylinder 8 is stopped, and the shift operation is performed. finish.

An engine such as a diesel engine is shown in FIG.
It has a rotation speed-torque characteristic with the fuel injection amount (throttle opening) as a parameter as shown in FIG. That is, the engine has a property that when the engine speed increases, the torque value rapidly decreases after the engine torque shows a certain maximum value in a state where the throttle opening is constant.
Driving the engine at the engine speed that exhibits the above-described maximum torque value, in other words, moving the engine to the higher engine torque side, increases efficiency and fuel efficiency.

[0013]

In the conventional shift control technique for the toroidal type continuously variable transmission described above, predetermined performance may not be obtained due to the accuracy of detection of the accelerator opening and vehicle speed, variations in parts, and the like. In particular, in an engine having a rotation speed-torque characteristic as shown in FIG. 5, for example, when the accelerator depression amount is 40%, it is ideal to control the operation at point A in the figure, but due to the detection accuracy and variations in parts, B It may be driven at point or C point. Particularly, at the engine speed side higher than the A point, such as at the point C, the torque sharply decreases as the engine speed increases, so that the obtained vehicle performance (acceleration performance, fuel efficiency performance) is significantly deteriorated. In the toroidal type continuously variable transmission, in view of such technical circumstances,
There is a problem that it is necessary to avoid the above-mentioned inconvenience that the actual torque value is reduced to a predetermined torque or less.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and in a toroidal continuously variable transmission, is it possible to detect an actual input torque value and reduce it to a predetermined torque value or less? If it is determined that the torque is less than or equal to a predetermined torque value, a toroidal type continuously variable transmission that can shift-control the toroidal transmission unit so that the input / output torque is optimally balanced in terms of engine output characteristics. Is to provide.

In order to achieve the above object, the present invention is configured as follows. That is, according to the present invention, the input disc and the output disc that are arranged to face each other, and a pair of the transmission of the rotation of the input disc that is steplessly changed according to the change of the tilt angle with respect to the both discs are transmitted to the output disc. A power roller, a pair of trunnions rotatably supporting the power roller and tilting about a tilt axis from a neutral position, a hydraulic cylinder having two cylinder chambers and displacing the trunnion in the tilt axis direction, A spool valve that shuts off the cylinder chamber when the spool is in the neutral position and selectively communicates the cylinder chamber with the hydraulic pressure source and the tank when the spool is displaced from the neutral position, and a spool position of the spool valve, respectively. A solenoid valve to control, a pressure sensor to detect the hydraulic pressure acting on each of the two cylinder chambers, a target gear ratio and an actual change. The operation of the solenoid valve is controlled in response to a control signal corresponding to a gear ratio deviation from the ratio, and is obtained from the pressure difference between both hydraulic pressures detected by the pressure sensor and the target gear ratio or the actual gear ratio. The present invention relates to a toroidal type continuously variable transmission including a controller that corrects the target gear ratio based on a torque deviation between an actual input torque and a target input torque that is determined based on information including at least information about the accelerator pedal depression amount.

Since this toroidal type continuously variable transmission is constructed as described above, the target gear ratio changes when the accelerator depression amount is changed or when the braking operation of the brake pedal or the like is performed. Since there is a gear ratio deviation between the target gear ratio and the actual gear ratio, the controller determines that a gear shift is necessary and performs gear shift control.
This toroidal type continuously variable transmission provides a pressure difference between hydraulic pressures acting on both cylinder chambers detected by a pressure sensor and an actual input torque obtained from the target gear ratio or the actual gear ratio, and at least information on an accelerator pedal depression amount. The target gear ratio is corrected based on the input torque deviation from the target input torque calculated based on the information included. In the toroidal type continuously variable transmission, the engine speed is high in the engine operating state, while the target gear ratio is corrected when the actual input torque is small, and the target gear ratio is adjusted to match the corrected target gear ratio. Since the shift control is performed in this manner, the engine speed is adjusted to match the output shaft speed and the engine output torque at that time. Therefore, with this toroidal type continuously variable transmission, it becomes possible to shift to an ideal operating point on the engine characteristic curve, and the gear shifting performance and the fuel consumption of the engine are improved.

Further, in this toroidal type continuously variable transmission, when the actual input torque is a value smaller than the target input torque, the controller increases the target speed ratio to the speed increasing side according to the difference between the two torque values. To correct.

In this toroidal type continuously variable transmission, when the engine speed is high and the engine output torque, that is, the actual input torque is smaller than the target input torque, the target gear ratio is set to the speed increasing side. The correction is performed in the upshift direction, and at this time, the shift control is performed by the normal gear ratio control so as to follow the corrected target gear ratio. In this toroidal type continuously variable transmission, when the shift is upshifted, the input shaft rotational speed corresponding to the output shaft rotational speed and the output torque at that time can be small, and the engine rotational speed can be reduced. Therefore, by the shift control of this toroidal type continuously variable transmission, the engine output torque increases, and it is possible to shift to an ideal operating point on the engine characteristic curve.

The controller stores in the memory the target input torque, the actual input torque, and the amount by which the target gear ratio should be corrected as a table obtained in advance. The target input torque and the actual input torque are calculated using the table from the detected values such as the accelerator pedal depression amount and the pressure difference in the cylinder chamber. The calculated both input torque and the target are further calculated using another table. The gear ratio correction amount is calculated. If an arithmetic expression such as an empirical equation is known instead of the table, the controller may perform arithmetic operation based on these empirical equations.

The solenoid valve for controlling the spool position of the spool valve may be a duty valve, a proportional valve or the like as long as it can electrically control the hydraulic pressure, and may be a two-way valve, a three-way valve or the like. Further, the solenoid valve may be one that can supply hydraulic pressure to both ends of the spool valve. Therefore, one solenoid valve may be connected to each end of the spool valve. Alternatively, one solenoid valve is connected to only one end of the spool valve, and a constant hydraulic pressure is applied to the other end of the spool valve, or a spring is provided at the other end. Good.
In that case, the spring force needs to be set high.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a toroidal type continuously variable transmission according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of a toroidal type continuously variable transmission according to the present invention. The toroidal type continuously variable transmission according to the present invention has substantially the same configuration as the conventional one shown in FIG. 4 except for the configuration related to the controller, and therefore, the same parts are designated by the same reference numerals, and overlapping description will be repeated. Is omitted.

In FIG. 1, an output shaft speed sensor 18 for detecting the output shaft speed of the toroidal type continuously variable transmission,
An engine speed sensor 19 for detecting the engine speed,
Accelerator pedal depression amount sensor 2 for detecting fuel supply amount
Information necessary for gear shifting from a sensor such as 0 is input to the controller 25.

Based on these pieces of information, the controller 25 calculates the optimum target gear ratio e ₀ for the driving situation by means of a table or an arithmetic expression stored inside. The controller 25 detects the actual gear ratio calculated from the combined displacement amount of the tilt angle of the trunnion 4 detected by the precess cam 15 and the potentiometer 17 and the tilt axis direction. Based on the gear ratio deviation between the target gear ratio e ₀ and the actual gear ratio, hydraulic pressures Sa and Sb are supplied from the solenoid valves 13a and 13b to both ends of the spool valve 10 to control the gear ratio deviation to zero. In terms of points, it is similar to the controller 14 of the conventional toroidal continuously variable transmission.

This toroidal type continuously variable transmission is different from the conventional one shown in FIG. 4 in that the hydraulic pressure supplied to the cylinder chambers 8a and 8b of the hydraulic cylinder 8 for displacing the trunnion 4 in the tilt axis direction is measured by a pressure sensor. The controller 25 to which the detected signal is input by 26a and 26b,
This is because the target gear ratio e ₀ was corrected, the spool valve 10 was operated to change the position of the trunnion 4 in the tilt axis direction, and the gear ratio was controlled. A pressure sensor 26a for detecting the oil pressure for the cylinder chamber 8a is provided in the conduit 9a, and a pressure sensor 26b for detecting the oil pressure for the cylinder chamber 8b is provided in the conduit 9b. The controller 25 receives the detection signals from the pressure sensors 26a and 26b and calculates the pressure difference ΔP between the hydraulic pressure Pup acting on the cylinder chamber 8a and the hydraulic pressure Pdown acting on the cylinder chamber 8b.

Actual input torque T of the toroidal type continuously variable transmission
In has a characteristic that it is proportional to the pressure difference ΔP under a constant gear ratio. If the actual input torque Tin is constant, the pressure difference ΔP opposes a force proportional to the contact rotation radius r1 between the input disk 3 and the power roller 2 (that is, related to the gear ratio e). Therefore, the actual input torque Tin can be calculated as a function of the pressure difference ΔP and the gear ratio e (the target gear ratio e ₀ may be used).

On the other hand, based on at least the accelerator pedal depression amount (throttle opening) θ detected by the accelerator pedal depression amount sensor 20 corresponding to the fuel supply amount, a table or an arithmetic expression stored in advance in the memory of the controller 25. From this, the target input torque (target input torque Tino) corresponding to the accelerator pedal depression amount (throttle opening) θ is calculated. Therefore, the actual input torque Ti
The torque deviation ΔTin can be calculated as the difference between n and the target input torque Tino.

When it is found that the sign of the torque deviation ΔTin is negative, that is, the actual input torque Tin is smaller than the target input torque Tino, the engine speed is changed as indicated by point C in FIG. The actual input torque Tin, which is also the engine output torque for the higher number
Is regarded as a small state, the target gear ratio is increased,
That is, the ratio of the input shaft rotational speed to the output shaft rotational speed is corrected in the upshift direction so as to be smaller. Gear ratio correction amount Δ
As for e, it is possible to experimentally find an appropriate correction amount for the torque deviation ΔTin and store it in the memory of the controller 25 in advance. Instead of this, the correction amount Δe may be obtained by approximately multiplying the torque deviation ΔTin by a proportional constant. If the sign of the torque deviation ΔTin is positive, that is, if it is found that the actual input torque Tin is not lower than the target input torque Tino, it is considered that the engine is operating in the optimum state, and the target shift The ratio e ₀ is not corrected.

For example, when a toroidal type continuously variable transmission is used in a vehicle, the actual input torque Ti which is also the engine output torque in spite of the high engine speed.
When n is small, if the target gear ratio e ₀ is corrected in the upshift direction so as to be on the speed-increasing side, the corrected target gear ratio e ₀ is followed by normal gear ratio control. Shift control is performed. When the shift is shifted up, the input shaft speed corresponding to the output shaft speed at that time can be small, and the engine speed can be reduced. Therefore, the engine output torque changes in the increasing direction, and it is possible to shift to the ideal operating point on the engine characteristic curve.

Next, the procedure of shift control of the toroidal type continuously variable transmission will be described with reference to the flow chart of FIG. Before the speed change operation is started, it is assumed that the trunnion 4 is in a so-called neutral position where the rotation center axis of the power roller 2 and the rotation center axes of the input disc 3 and the output disc 23 intersect each other. May have an arbitrary shift position.

In the main routine, the gear ratio control is performed according to the deviation between the target input torque and the actual input torque. That is, the engine speed sensor 19, the accelerator pedal depression amount 20, the vehicle speed sensor, that is, the output shaft rotation sensor 18, and other sensors in the shift information detector 30 are used to shift gears such as engine speed, accelerator pedal depression amount, and transmission output shaft speed. Information is detected. Based on the detected gear shift information, the controller 25 calculates an optimum target gear ratio by means such as a table or an arithmetic expression stored therein, and sets this as the target gear ratio e ₀ (step S1). . The control for matching the actual gear ratio with the target gear ratio e ₀ is executed in the main routine.

Based on the accelerator pedal depression amount (throttle opening degree) θ, the target input torque Tino is selected from, for example, a table [Tino = f1 (θ)] stored in the memory of the controller 25. When a driver wants to accelerate an automobile, he or she depresses the accelerator pedal largely without changing the gear ratio to increase the torque transmitted to the transmission output shaft. At this time, if there is a loss in the target input torque to the toroidal type continuously variable transmission, that is, if there is a loss in the power transmission path from the engine to the toroidal type continuously variable transmission, the engine output torque including the loss is High target input torque Tin
o is set (step S2). Target input torque Ti
The setting of no need not depend only on the accelerator pedal depression amount θ, but may depend on the accelerator pedal depression speed,
Alternatively, generally, it may be determined in advance by a map or the like according to the driving situation.

As a premise for calculating the actual input torque, the hydraulic pressure Pu acting on the cylinder chambers 8a and 8b of the hydraulic cylinder 8 is set.
The pressure difference ΔP between p and Pdown is calculated, and the pressure difference ΔP =
Pup-Pdown is calculated (step S3).

The pressure difference ΔP represents the force F of the trunnion 4 in the tilt axis direction, and at a constant gear ratio, the actual input torque Ti.
It is proportional to n. On the other hand, the pressure difference ΔP is proportional to the contact rotation radius r ₁ between the input disk 3 and the power roller 2 (a function of the actual gear ratio e) at a constant input torque. Therefore,
The actual input torque Tin becomes a function of the pressure difference ΔP and the actual gear ratio e, that is, Tin = f2 (ΔP, e) (step S4).

The target input torque Tino calculated in step S2 and the actual input torque T calculated in step S4
The torque deviation ΔTin is calculated as the difference with in (ΔTin
= Tin-Tin o) (step S5).

Torque deviation ΔT calculated in step S5
It is determined whether in is a positive value or a negative value (step S6). If the torque deviation ΔTin is a positive value,
Since the actual input torque Tin is larger than the target input torque Tino, it means that the torque is not insufficient, the process returns to the main routine of step S9, and the normal gear ratio control is performed. .

When it is determined that the torque deviation ΔTin is a negative value in the torque deviation sign determination in step S6, the actual input torque Tin is equal to the target input torque Tin.
It is considered that the engine is operating in a state where the engine speed is smaller than o and the torque is insufficient, that is, the engine speed is higher than the target speed. In order to reduce the engine speed,
The target gear ratio e ₀ is controlled so as to be corrected to the side where the output shaft speed is increased. The correction amount of the target gear ratio e ₀ is obtained from a table or an arithmetic expression stored in the memory of the controller 25. That is, the correction amount Δe = f3 (ΔTin) (step S7).

The target gear ratio e ₀ before correction is corrected by the gear ratio correction amount Δe obtained in step S7 (e ₀ = e + Δ
e) (step S8). If the target speed ratio e ₀ corrected in step S8 is determined, the flow returns to the main routine (step S9), and matching the target transmission ratio e ₀ the corrected target transmission ratio e ₀ as a new target speed change ratio e ₀ Thus, the actual gear ratio is controlled by performing the same gear shifting operation as in the conventional case. The engine will have a reduced rotational speed in order to meet the speed ratio that shifts to match the new corrected target speed ratio e ₀ and the small actual input torque.

[0038]

Since the toroidal type continuously variable transmission according to the present invention is constructed as described above, the detection accuracy of the output shaft speed of the transmission and the accelerator pedal depression amount (that is, the throttle opening), or Inaccuracies in engine characteristics due to variations in parts can be absorbed by the control of the controller, and the engine can be kept in an ideal operating state. For example, even in the case of an engine having a characteristic such that the output torque sharply decreases when the engine is operated at a higher rotational speed than the target engine rotational speed, such as a diesel engine, the output shaft rotational speed of the transmission and the throttle When it is detected that the engine speed becomes higher than the target speed and the actual input torque decreases compared with the target input torque due to the detection accuracy of the opening degree or the variation of parts, the torque deviation is determined according to the torque deviation. The target gear ratio of the toroidal type continuously variable transmission can be corrected so that the engine can be operated at an appropriate rotational speed. Therefore, by using this toroidal type continuously variable transmission, it is possible to secure predetermined performance with respect to engine acceleration and fuel consumption.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a toroidal type continuously variable transmission according to the present invention.

FIG. 2 is a flowchart showing a procedure of control for obtaining a correction amount of a target gear ratio according to a deviation between an actual input torque and a target input torque in the toroidal continuously variable transmission of FIG.

FIG. 3 is a diagram showing an outline of a conventional toroidal type continuously variable transmission.

FIG. 4 is a circuit diagram showing an outline of a gear ratio control of a conventional toroidal type continuously variable transmission.

FIG. 5 is a diagram showing an engine speed-torque characteristic.

[Explanation of symbols]

 1 Transmission Unit 2 Power Roller 3 Input Disc 4 Trunnion 6 Tilting Shaft 8 Hydraulic Cylinder 8a, 8b Cylinder Chamber 10 Spool Valve 11 Spool 13a, 13b Solenoid Valve 17 Potentiometer 20 Accelerator Pedal Depth Sensor 25 Controller 26 Pressure Sensor

Claims (3)

[Claims] 1. An input disk and an output disk, which are arranged to face each other, and a pair of powers for continuously changing the rotation of the input disk in response to changes in a tilt angle with respect to the both disks and transmitting the rotation to the output disk. A roller, a pair of trunnions that rotatably support the power roller and tilt around a tilt axis from a neutral position, and a hydraulic cylinder that has two cylinder chambers and that displaces the trunnion in the tilt axis direction, spool A spool valve that shuts off the cylinder chamber in the neutral position and selectively communicates the cylinder chamber with a hydraulic pressure source and a tank while the cylinder chamber is displaced from the neutral position, and controls the spool position of the spool valve. Solenoid valve, a pressure sensor that detects the hydraulic pressure acting on each of the two cylinder chambers, and a target gear ratio and an actual gear ratio. An actual input torque obtained from the pressure difference between the two hydraulic pressures detected by the pressure sensor and the target gear ratio or the actual gear ratio while controlling the operation of the solenoid valve in response to a control signal corresponding to the gear ratio deviation. And a controller that corrects the target gear ratio based on a torque deviation from a target input torque that is determined based on information including at least information on the accelerator pedal depression amount, a toroidal continuously variable transmission. 2. The controller is controlled to correct the target gear ratio to the speed increasing side according to the torque deviation when the actual input torque is a value smaller than the target input torque. The toroidal type continuously variable transmission described in 1. 3. The toroidal according to claim 1, wherein the target input torque, the actual input torque, and a correction amount for correcting the target gear ratio are stored in the controller as a table or an arithmetic expression obtained in advance. Type continuously variable transmission.