JP2013151983A - Control device for continuously variable transmission employing traction drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a continuously variable transmission employing a traction drive system, which is capable of setting a pressing load with excess and deficiency of a load suppressed.SOLUTION: A control device 1 for a continuously variable transmission 10 employing a traction drive system calculates a target traction coefficient in an actual operation based on the estimated value of a maximum traction coefficient and an allowance rate, and sets a target pressing load between input disks 11A, 11B and power rollers 13A, 13B and between output disks 12A, 12B and the power rollers 13A, 13B, based on the target traction coefficient. The control device varies the allowance rate in accordance with a ratio of the solid region to the fluid region of traction oil present at a contact point between the power rollers 13A, 13B and at least either the input disks 11A, 11B or the output disks 12A, 12B.

Description

  The present invention includes first and second power transmission elements that rotate about separate rotation shafts while being pressed against each other, and power transmission between the first and second power transmission elements is interposed between the contact points of each other. The present invention relates to a control device for a traction drive type continuously variable transmission performed through an oil film of the traction oil.

  Conventionally, as one of continuously variable transmissions of this type, with respect to the first and second rotation elements as one power transmission element having a common first rotation center axis, and the first rotation center axis A rolling member as the other power transmission element having a second rotation center axis arranged in a plurality of radial directions, and tilting each rolling member sandwiched between the first rotation element and the second rotation element. Thus, there is known one that changes the gear ratio between input and output steplessly.

  Specifically, for example, a toroidal continuously variable transmission including an input disk as a first rotating element, an output disk as a second rotating element, and a power roller as a rolling member is applicable. In this toroidal-type continuously variable transmission, a pressing load is applied between the input and output disks and the power roller, and the traction oil film interposed between these contacts is interposed between the input and output disks. Power transmission. At this time, the control device for the continuously variable transmission sets the pressing load by dividing the traction force at the contact by the traction coefficient. When setting the pressing load, the control device uses the target value of the traction coefficient obtained by dividing the estimated value of the maximum traction coefficient by the margin ratio as the traction coefficient at the time of calculation. This is because the estimated value of the maximum traction coefficient is deviated from the actual measurement value, and there is no fixed law for the deviation width. For example, the divergence width decreases when the input torque to the input disk is large and increases when the input torque is small, but the degree of divergence with respect to the input torque is not necessarily regular. Here, the following Patent Document 1 discloses a technique for estimating a lubricating oil temperature at a contact point between an input disk or an output disk and a power roller and obtaining a target value of a traction coefficient based on the lubricating oil temperature. ing. In this patent document 1, the friction coefficient of the solid region (fluid solidification region) and the friction coefficient of the fluid region (fluid viscosity region) in the lubricating oil of the contact point are obtained based on the lubricating oil temperature, and the friction coefficient of the solid region is contacted. The maximum traction coefficient is estimated based on the sum of the ratio of the solid area in the ellipse and the friction coefficient of the fluid area multiplied by the ratio of the fluid area in the contact ellipse. The target value of the traction coefficient is obtained by dividing by (1 / safety coefficient).

  Patent Document 2 below discloses the stress distribution at the contact point of the toroidal-type continuously variable transmission, and the shear characteristics of the plastic region and the viscous region at the contact point.

  Patent Document 3 below discloses a traction drive type continuously variable transmission having a ball planetary continuously variable transmission mechanism. In this ball planetary continuously variable transmission, a pressing load is applied to the rolling member (planetary ball) from at least one of the two rotating elements. Further, in Patent Document 4 below, two conical rotating bodies (cones) arranged on the torque input side and the output side, respectively, and one rotating body are inserted, and each of the rotating bodies is inserted. A cone ring type continuously variable ring that has an outer circumferential surface and an inner circumferential surface sandwiched between inclined surfaces, and that changes the gear ratio steplessly by moving the annular body in the axial direction. A traction drive type continuously variable transmission having a speed change mechanism is disclosed. Also in this cone ring type continuously variable transmission, a pressing load is applied between the rotating body and the annular body.

JP 2004-108482 A JP 2003-120774 A JP 2011-231929 A JP 2011-225202 A

  By the way, in the toroidal-type continuously variable transmission described in Patent Document 1, a deviation between the estimated value of the maximum traction coefficient and the actually measured value is corrected with a margin rate. However, this technique does not take into consideration that the calculation accuracy of the friction coefficient differs between the solid region and the fluid region, so the maximum traction coefficient is estimated as the ratio of the solid region to the fluid region changes. There is a possibility that the difference between the measured value and the actual value cannot be corrected, and the accuracy of the target value of the traction coefficient is lowered. Therefore, when such a precision drop occurs, if there is an excess or deficiency in the set value of the pressing load applied to at least one of the input disk and the output disk, the pressing load between the input disk, the output disk and the power roller Slip occurs due to shortage, and excessive pressing load causes deterioration in durability, power transmission efficiency, and torque capacity. Also, in the ball planetary continuously variable transmission and the cone ring continuously variable transmission described in Patent Documents 3 and 4, there is a possibility that the set value of the pressing load may be excessive or insufficient as in the toroidal type. is there.

  Accordingly, an object of the present invention is to provide a control device for a traction drive type continuously variable transmission that can improve the inconveniences of the conventional example and can set a pressing load while suppressing excess and deficiency.

  In order to achieve the above object, the present invention calculates a target traction coefficient in actual driving based on the estimated value of the maximum traction coefficient and a margin rate, and based on the target traction coefficient, In a control device for a traction drive type continuously variable transmission that sets a target pressing load with respect to a second power transmission element, the traction interposed at a contact point between the first power transmission element and the second power transmission element The margin is changed in accordance with the ratio of the oil solid region to the fluid region.

  Here, it is desirable to set the margin rate larger as the fluid region increases in the traction oil interposed in the contact.

  Further, when the margin ratio when the solid area and the fluid area are the same area is set as a reference margin ratio, the margin ratio is greater than the reference area if the solid area is wider than the fluid area. On the other hand, if the fluid area is wider than the solid area, it is desirable to set it to be larger than the reference margin ratio.

  The control device for the traction drive type continuously variable transmission according to the present invention sets a margin rate according to the ratio of the solid region and the fluid region in the traction oil of the contact point, so that the target traction set using this margin rate The accuracy of the coefficient can be improved. Therefore, this control device can set the target pressing load without excess or deficiency using the target traction coefficient, and can suppress the occurrence of slip due to insufficient pressing load at each contact, It is possible to suppress a decrease in durability and power transmission efficiency due to the pressing load. Further, this control device can avoid a decrease in torque capacity due to an excessive pressing load.

FIG. 1 is a diagram showing a toroidal continuously variable transmission and a control device. FIG. 2 is a diagram for explaining trunnions. FIG. 3 is a diagram illustrating the relationship between the traction oil region classification and the pressure distribution at the contact point. FIG. 4 is a diagram showing an example of a map of the margin ratio with respect to the area ratio between the solid region and the fluid region. FIG. 5 is a flowchart for explaining the arithmetic processing operation when setting the target traction coefficient.

  Embodiments of a control device for a traction drive type continuously variable transmission according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

[Example]
An embodiment of a control device for a traction drive type continuously variable transmission according to the present invention will be described with reference to FIGS.

  First, a traction drive type continuously variable transmission to which the control device of this embodiment is applied will be described. The continuously variable transmission includes first and second power transmission elements that rotate about separate rotating shafts while being pressed against each other, and transmit power between the first and second power transmission elements. This is performed through an oil film of traction oil interposed between the contacts. In this continuously variable transmission, since the gear ratio between the input and output is changed steplessly by tilting the rotation shaft of the second power transmission element, this second power transmission element is a power transmission element for power transmission. At the same time, it becomes a shift element for shifting.

  As an example of this type of continuously variable transmission, first and second rotating elements having a common first rotation center axis R1 and a plurality of second rotations arranged radially with respect to the first rotation center axis R1. A rolling member having a central axis R2, and inclining each rolling member sandwiched between the first rotating element and the second rotating element to change the transmission ratio between input and output steplessly. Things are known. In this continuously variable transmission, power is transmitted between the first rotating element and each rolling member, and between the second rotating element and each rolling member. Therefore, in this continuously variable transmission, the first and second rotating elements each correspond to a first power transmission element, and each rolling member corresponds to a second power transmission element. In this continuously variable transmission, unless otherwise stated, the direction along the first rotation center axis R1 is referred to as the axial direction, and the direction around the first rotation center axis R1 is referred to as the circumferential direction. Further, the direction orthogonal to the first rotation center axis R1 is referred to as a radial direction, and among these, the inward side is referred to as a radial inner side, and the outward side is referred to as a radial outer side.

  In this embodiment, a toroidal continuously variable transmission will be described as an example. The toroidal continuously variable transmission may have either a full toroidal or half toroidal continuously variable transmission mechanism.

  Reference numeral 10 in FIG. 1 is an example of this toroidal continuously variable transmission, and shows the main part thereof. The continuously variable transmission 10 includes input disks 11A and 11B as first rotating elements, output disks 12A and 12B as second rotating elements, power rollers 13A and 13B as rolling members, and a power source (illustrated). A shaft 14 serving as an input shaft to which the output torque is transmitted.

  In the continuously variable transmission 10, the input disks 11A and 11B, the output disks 12A and 12B, and the shaft 14 have a common first rotation center axis R1, and the respective power rollers 13A and 13B are individually rotated in the second direction. It has a central axis R2. The first rotation center axis R1 and one second rotation center axis R2 are arranged on the same tilt plane. The same tilt plane is formed for each of the power rollers 13A and 13B.

  The input disks 11A and 11B and the output disks 12A and 12B have a disc shape and are arranged concentrically with the shaft 14. At that time, the output disks 12A and 12B are arranged between the input disks 11A and 11B. Contact surfaces 11a and 12a forming a cavity C1 are formed on the opposing surfaces of the input disk 11A and the output disk 12A, respectively. Similarly, contact surfaces 11b and 12b forming a cavity C2 are formed on the opposing surfaces of the input disk 11B and the output disk 12B, respectively.

  The input disks 11 </ b> A and 11 </ b> B rotate integrally with the shaft 14 in the circumferential direction and can move relative to the shaft 14 in the axial direction. For example, the input disks 11 </ b> A and 11 </ b> B are splined to the shaft 14. As a result, the input disks 11A and 11B rotate integrally with the shaft 14 and can move relative to the shaft 14 in the axial direction. For this reason, the output torque of the power source is transmitted to the input disks 11A and 11B, and the input disks 11A and 11B are pushed toward the output disks 12A and 12B by a thrust generating unit 15 described later. On the other hand, the output disks 12A and 12B can rotate relative to the shaft 14 in the circumferential direction via bearings (not shown). The output disks 12A and 12B are connected to the drive wheels through a gear group, and transmit the output torque of the power source transmitted through the power rollers 13A and 13B to the drive wheels.

  In the continuously variable transmission 10, a plurality of power rollers 13A are radially arranged around the first rotation center axis R1 in the cavity C1. Similarly, in the cavity C2, a plurality of power rollers 13B are arranged radially about the first rotation center axis R1. In the continuously variable transmission 10, each power roller 13A is sandwiched between the input disk 11A and the output disk 12A, and each power roller 13B is sandwiched between the input disk 11B and the output disk 12B.

  Each of the power rollers 13A and 13B is individually supported by a trunnion 16 shown in FIG. 2, and can rotate relative to the trunnion 16 around the second rotation center axis R2. In other words, the power rollers 13A and 13B are supported by the trunnion 16 so as to be able to rotate relative to the input disks 11A and 11B and the output disks 12A and 12B. The trunnion 16 moves the power rollers 13A and 13B in the radial direction with respect to the input disks 11A and 11B and the output disks 12A and 12B, and at the same time the power roller 13A with respect to the input disks 11A and 11B and the output disks 12A and 12B. , 13B can be tilted.

  In the continuously variable transmission 10, by changing the tilt angle of the power rollers 13A and 13B on the tilt plane, the rotation ratio between the input disk 11A and the output disk 12A and the input disk 11B and The rotation ratio with the output disk 12B is changed, thereby changing the speed ratio γ. Therefore, a tilting device that tilts the respective power rollers 13A and 13B is used for the transmission (not shown) of the continuously variable transmission 10. For example, in this speed change device, the power rollers 13A and 13B are stroked from the neutral position to the speed change position by hydraulic pressure so that a tilting force is applied to the power rollers 13A and 13B, thereby tilting the power rollers 13A and 13B. A hydraulic servo mechanism that rotates is known. This transmission is controlled by the control device 1. The neutral position means a state where the second rotation center axis R2 of the power rollers 13A and 13B intersects the first rotation center axis R1. On the other hand, the shift position is a position where the power rollers 13A and 13B are offset from the neutral position, and means a state in which the second rotation center axis R2 does not intersect the first rotation center axis R1.

  Here, the distance from the first rotation center axis R1 to the contact point between the power roller 13A (13B) and the input disk 11A (11B) is referred to as an input contact distance, and the first rotation center axis R1 to the power roller 13A (13B). ) And the output disk 12A (12B) to the contact point is called the output contact point distance. In this example, when the input contact distance and the output contact distance are the same distance, the input disks 11A and 11B and the output disks 12A and 12B rotate at the same rotational speed. The gear ratio γ of the machine 10 becomes 1. For this reason, in this continuously variable transmission 10, this state is called a state where the tilt angle is 0 degree. In the continuously variable transmission 10, the upper power roller 13A in FIG. 1 is tilted counterclockwise from the position where the gear ratio γ is 1, and the lower power roller 13A in FIG. Is shifted clockwise (γ> 1). When shifting to the deceleration side, the upper power roller 13B in FIG. 1 is tilted clockwise, and the lower power roller 13B in FIG. 1 is tilted counterclockwise. On the other hand, in the continuously variable transmission 10, the upper power roller 13A in FIG. 1 is tilted clockwise from the position where the gear ratio γ is 1, and the lower power roller 13A in FIG. By tilting counterclockwise, the gear ratio γ changes to the speed increasing side (γ <1). When shifting to the speed increasing side, the upper power roller 13B in FIG. 1 is tilted counterclockwise, and the lower power roller 13B in FIG. 1 is tilted clockwise.

  The power roller 13A is in contact with the input disk 11A and the output disk 12A via an oil film of traction oil, and axial force (thrust) is applied from the input disk 11A and the output disk 12A. Similarly, the power roller 13B is in contact with the input disk 11B and the output disk 12B via an oil film of traction oil, and axial force (thrust) is applied from the input disk 11B and the output disk 12B. Yes. Accordingly, at each contact point, a normal direction pressing load (normal force) Fn corresponding to the shape of the power rollers 13A and 13B and the cavities C1 and C2 and the thrust from the input disk 11A and the output disk 12A is applied. Yes. The pressing load Fn is calculated by the traction force Ft and the traction coefficient μ (Fn = Ft / μ).

  The continuously variable transmission 10 is provided with a thrust generator 15 that generates the thrust. Here, a thrust generating portion 15 is disposed on each of the input disks 11A and 11B. The thrust generator 15 on the input disk 11A side controls the hydraulic pressure of the hydraulic chamber provided on the back side of the input disk 11A (the side opposite to the contact point with the power roller 13A) by the control device 1 to increase or decrease the opposing output. A target thrust toward the disk 12A is generated. Further, the thrust generator 15 on the input disk 11B side is controlled by increasing / decreasing the hydraulic pressure of the hydraulic chamber provided on the back side of the input disk 11B (the side opposite to the contact point with the power roller 13B) by the control device 1. The target thrust toward the output disk 12B to be generated is generated.

  The target thrust of the thrust generator 15 depends on the target pressing load Fn0 from the input disks 11A and 11B and the output disks 12A and 12B to the power rollers 13A and 13B and the geometric condition of the continuously variable transmission 10. Determined. The geometric condition is a shape that determines the load direction of the pressing load Fn (shapes of the cavities C1, C2, power rollers 13A, 13B, etc.) and the like, and is one of the specification information of the continuously variable transmission 10. is there. The target pressing load Fn0 is calculated from the target traction force Ft0 and the target traction coefficient μ0 (Fn0 = Ft0 / μ0). The target traction coefficient μ0 is a target value of the traction coefficient μ set by dividing the estimated maximum traction coefficient μmax by the margin ratio rm, and is the traction coefficient μ in actual driving. Yes (μ0 = μmax / rm). Therefore, the control device 1 determines the target traction coefficient μ0 based on the estimated maximum traction coefficient μmax and the margin rate rm, and calculates the target pressing load Fn0 from the target traction coefficient μ0 and the target traction force Ft0. Thereafter, the control device 1 calculates the target thrust based on the target pressing load Fn0 and the geometric condition of the continuously variable transmission 10, and obtains the hydraulic pressure in the hydraulic chamber of the thrust generating unit 15 that outputs the target thrust. . The outline of these calculations is well known in the technical field of this type of continuously variable transmission 10.

  Here, the maximum traction coefficient μmax is determined by the contact (input side contact) on the rolling track between the input disks 11A and 11B and the power rollers 13A and 13B, and the output disks 12A and 12B and the power rollers 13A and 13B. It is determined by the surface pressure and slip rate of the contact point on the rolling track (contact point on the output side), the temperature in the oil film of the traction oil at that contact point, and the like. For this reason, conventionally, the maximum traction coefficient μmax is estimated based on the temperature in the oil film of the traction oil. However, it is difficult to estimate the oil film temperature with high accuracy, and it is difficult to improve the estimation accuracy of the maximum traction coefficient μmax.

  Therefore, in this embodiment, the contact ellipse at the contact point is divided into a plurality of pieces, and the maximum traction coefficient μmax is estimated by integrating the maximum shear stress of the traction oil for each of the sections. In this exemplary control device 1, as shown in FIG. 3, the contact ellipse is partitioned into a lattice shape, and the maximum shear stress of the traction oil for each lattice is integrated. Further, at the time of the estimation, the target contact is at least the contact between the input disks 11A and 11B and the power rollers 13A and 13B or the contact between the output disks 12A and 12B and the power rollers 13A and 13B. It only has to be one.

  Here, as to how many contact ellipses are classified, the area of this contact ellipse, the calculation load of the maximum shear stress in all lattices, the estimation accuracy of the maximum traction coefficient μmax, the solid region in all lattices to be described later, etc. Is set such that the accuracy of the target traction coefficient μ0 can be improved while suppressing the overload of the calculation based on the calculation load related to the calculation, the calculation load of the margin ratio rm, the calculation accuracy of the target traction coefficient μ0, and the like.

  The margin rate rm corresponds to a correction value or correction coefficient for bringing the estimated value of the maximum traction coefficient μmax close to the actual measurement value. This margin ratio rm is set based on the area ratio between the solid region of the traction oil and the fluid region in the contact ellipse (= the area of the solid region / the area of the fluid region). Here, for example, each area in the case where the solid area and the fluid area have the same area is defined as a reference area, and a margin ratio rm in this case is defined as a reference margin ratio.

  At the contact point between the input disks 11A and 11B and the power rollers 13A and 13B and the contact point between the output disks 12A and 12B and the power rollers 13A and 13B, the traction oil has a traction force Ft between them (in other words, a pressure). ) Can be broadly divided into plastic and viscous areas. The plastic region is a solid region that has a solid-like property and is less susceptible to the influence of temperature than the viscous region. The viscous region has a fluid-like property and is a fluid region in which the influence of temperature tends to occur on the solid region. As shown in FIG. 3, the solid region is a region that exists in a place where the pressure is higher than that of the fluid region. Therefore, the fluid region exists outside the solid region in the contact ellipse.

  The margin ratio rm is set in consideration of the properties of each region. First, the solid region is less susceptible to temperature than the fluid region, and the error in the estimated value of the oil film temperature is small, so the difference between the estimated value of the maximum traction coefficient μmax and the measured value is small. For this reason, as shown in FIG. 4, when the solid region is wider than the reference area, the control device 1 sets the margin rate rm to be smaller than the reference margin rate. In the illustration of FIG. 4, the margin rate rm is reduced as the solid region is larger than the fluid region. However, the margin rate rm when the solid region is larger has a proportional relationship with the area ratio. Need not be. On the other hand, the fluid region is more susceptible to temperature than the solid region, and the error in the estimated value of the oil film temperature increases, so the difference between the estimated value of the maximum traction coefficient μmax and the measured value is also large. Become. For this reason, the control device 1 causes the margin ratio rm to be set larger as the fluid region increases with the traction oil interposed in the contact. Here, when the fluid region is wider than the reference area, the margin ratio rm is set larger than the reference margin ratio. In the illustration of FIG. 4, the margin rate rm is increased as the fluid region is larger than the solid region. However, the margin rate rm when the fluid region is larger has a proportional relationship to the area ratio. Need not be.

  Hereinafter, the calculation processing operation when the control device 1 sets the target traction coefficient μ0 will be described based on the flowchart of FIG.

  First, the control device 1 acquires information necessary for controlling the continuously variable transmission 10 (step ST1). In this step ST1, for example, the input torque to the continuously variable transmission 10, the number of revolutions of the continuously variable transmission 10, the speed ratio γ of the continuously variable transmission 10, the temperature of the continuously variable transmission 10, etc. are acquired (detected and calculated). Or estimated). The input torque is the torque from the power source that is input to the input disks 11A and 11B when the power source (not shown) of the vehicle is driven. For example, braking is not performed by the power source. When traveling or coasting, this is the torque from the drive wheels input to the output disks 12A and 12B. The rotation speed of the continuously variable transmission 10 is the rotation speed on the input side or the rotation speed of the power rollers 13A and 13B. The rotational speed on the input side is the rotational speed of the input disks 11A and 11B when driving, and the rotational speed of the output disks 12A and 12B when traveling while being driven. Further, the temperature of the continuously variable transmission 10 refers to the oil film temperature of the traction oil at the contact points described above, the surface temperature of the power rollers 13A and 13B, and the like.

  The control device 1 divides the contact ellipses of the contacts into a lattice shape, and determines whether the traction oil is a solid region or a fluid region for each lattice (step ST2). At that time, the control device 1 estimates the shape and size of the contact ellipse from the acquired information in step ST1, for example. In addition, the control device 1 may partition the contact ellipse into a predetermined lattice shape (the size and number of lattices) set in advance, and the size of the lattice may be determined according to the area of the contact ellipse. The number may be changed. Further, the region classification is determined based on, for example, the acquisition information in step ST1 or the estimated value of the pressing load at the contact point. At this time, when two regions are mixed in one lattice, the region is classified into a region having a larger exclusive area.

  The control device 1 estimates the maximum shear stress of the traction oil for each divided grid (step ST3), and estimates the maximum traction coefficient μmax by integrating each maximum shear stress (step ST4). The maximum shear stress is estimated from the acquired information in step ST1, the estimated value of the pressing load at the contact point, and the like.

  Further, the control device 1 calculates the area ratio between the solid region of the traction oil and the fluid region (= area of the solid region / area of the fluid region) in the contact ellipse (step ST5). Then, the control device 1 compares the area ratio with the map of FIG. 4 and sets a margin ratio rm corresponding to the area ratio (step ST6). Thereafter, the control device 1 calculates a target traction coefficient μ0 based on the estimated maximum traction coefficient μmax and the set margin rate rm (μ0 = μmax / rm), and uses this to set the target traction when the target pressing load is set. The coefficient μ0 is set (step ST7).

  As described above, according to the control device 1 of the present embodiment, the margin ratio rm is set in accordance with the area ratio between the solid region and the fluid region (= the solid region area / the fluid region area) in the contact traction oil. Therefore, it is possible to improve the accuracy of the target traction coefficient μ0 set using the margin rate rm. Therefore, the control device 1 can set the target pressing load Fn0 without excess or deficiency using the target traction coefficient μ0, and can suppress the occurrence of slip due to insufficient pressing load at each contact. Further, it is possible to suppress a decrease in durability and power transmission efficiency due to an excessive pressing load. Further, the control device 1 can avoid a decrease in torque capacity due to an excessive pressing load.

  Incidentally, the margin ratio rm is, for example, the ratio of the integral value of the shear stress in the solid region and the fluid region (= the integral value of the shear stress in the solid region / the shear stress in the fluid region) instead of the area ratio of the solid region and the fluid region. Or the ratio of the pressure distribution in the solid region to the fluid region (= the area of the pressure distribution in the solid region / the area of the pressure distribution in the fluid region). An effect can be obtained.

  The case of setting by the ratio of integral values of shear stress will be described. As in the case of using the above area ratio, the contact ellipses are partitioned in a lattice shape, and are classified into a solid region and a fluid region of traction oil, and respective shear stresses are obtained. Then, the shear stress in the solid region is integrated, the shear stress in the fluid region is also integrated, and the respective integrated values are compared. Here, the shear stress in the solid region is larger than the shear stress in the fluid region. For this reason, even if the area ratio between the solid region and the fluid region is 1, the integral value of the shear stress is larger in the solid region than in the fluid region. Becomes dominant.

  Here, the margin rm when the ratio of the integral value of the shear stress in the solid region and the fluid region is 1 is defined as the reference margin. When the integral value of the shear stress in the solid region is larger than that in the fluid region and the ratio is larger than 1, the margin rate rm is set smaller than the reference margin rate. On the other hand, when the integral value of the shear stress in the fluid region is larger than that in the solid region and the ratio is smaller than 1, the margin rate rm is set larger than the reference margin rate.

  The case of setting by the area ratio of the pressure distribution will be described. The distinction between the solid region and the fluid region is largely determined by the pressure and the temperature in the oil film. However, since it is difficult to estimate the temperature in the oil film, the distinction between the solid region and the fluid region is simply performed by the pressure. For this reason, in this case, the contact ellipse is divided into a lattice shape, and the respective pressures are obtained to classify the solid region into the traction oil solid region and the fluid region. Then, the area of the pressure distribution in the solid region and the area of the pressure distribution in the fluid region are obtained, and the ratio of these areas is calculated. Here, the margin rm when the area ratio of the pressure distribution is 1 is defined as the reference margin. When the area of the pressure distribution in the solid region is wider than that of the fluid region and the area ratio is larger than 1, the margin rate rm is set smaller than the reference margin rate. On the other hand, when the area of the pressure distribution in the fluid region is wider than that in the solid region and the ratio is smaller than 1, the margin rate rm is set larger than the reference margin rate.

  In the above examples, the toroidal type continuously variable transmission 10 has been described as an example. However, as described above, the traction drive type continuously variable transmission includes a ball planetary continuously variable transmission and a cone ring. There are also continuously variable transmissions of the type. Even in the ball planetary type or cone ring type continuously variable transmission, there is a possibility that the set value of the pressing load is excessive or insufficient. For this reason, in this ball planetary type or cone ring type continuously variable transmission, the margin ratio rm is set according to the area ratio of the solid region to the fluid region in the traction oil of each contact point, as in the toroidal type. Alternatively, the same effect as that of the toroidal type can be obtained. In the ball planetary continuously variable transmission, the first and second rotations have a common first rotation center axis R1 and sandwich the rolling members that rotate on the second rotation center axis R2. Each element corresponds to a first power transmission element. Each rolling member corresponds to a second power transmission element. On the other hand, in a cone ring type continuously variable transmission, for example, two conical rotators (cones) correspond to the first power transmission element, and an annular body (ring) sandwiched between the two motive powers. Corresponds to the transfer element.

DESCRIPTION OF SYMBOLS 1 Control apparatus 10 Continuously variable transmission 11A, 11B Input disk 12A, 12B Output disk 13A, 13B Power roller 15 Thrust generating part R1 1st rotation center axis R2 2nd rotation center axis

Claims (3)

A target traction coefficient for actual driving is calculated based on the estimated value of the maximum traction coefficient and the margin ratio, and target pressing between the first power transmission element and the second power transmission element is performed based on the target traction coefficient. In a control device for a traction drive type continuously variable transmission that sets a load,
A margin of traction drive type, characterized in that the margin ratio is changed in accordance with a ratio of a solid region and a fluid region of traction oil interposed at a contact point between the first power transmission element and the second power transmission element. Control device for step transmission.   2. The control device for a traction drive type continuously variable transmission according to claim 1, wherein the margin ratio is set to be larger as the fluid region increases in the traction oil interposed in the contact.   When the margin ratio when the solid area and the fluid area are the same size is a reference margin ratio, the margin ratio is the reference margin ratio if the solid area is wider than the fluid area. 3. The traction drive type continuously variable transmission according to claim 1, wherein the traction drive type continuously variable transmission is set to be larger than the reference margin rate if the fluid region is wider than the solid region. Machine control device.

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