JP4309204B2 - Toroidal CVT controller - Google Patents

Description

  The present invention relates to a control device for a shift operation in a toroidal CVT (continuously variable transmission).

  Conventionally, there is a torque cam method as a method for applying a pressing force to a disk roller in a toroidal CVT. In this torque cam system, the pressing force is automatically determined by the transmission torque, so the pressing force control mechanism is simplified, but it cannot follow that the traction coefficient changes due to other conditions such as the gear ratio. However, proper pressing force control cannot always be performed.

  For this reason, it has been proposed to change the pressing force in accordance with the gear ratio or the like using a hydraulic pressing device (Patent Document 1). According to this method, since the pressing force can be freely controlled, it is possible to operate with a constant traction coefficient regardless of the gear ratio and the like, and to perform efficient torque transmission at the optimum pressing force.

JP 2001-12573 A

  However, in the above prior art, the pressing force is controlled in consideration of the speed ratio, but the speed is constant, that is, the offset of the roller rotation shaft is considered to be zero, and the roller rotation direction (drive direction) during the speed change is considered. The reduction of the maximum traction coefficient is not considered. However, during shifting, the offset of the roller occurs, so the maximum traction coefficient in the driving direction decreases, and the margin for the maximum traction coefficient decreases. For this reason, an excessive slip occurs depending on the operating conditions, and the rolling member is damaged and the efficiency and durability are deteriorated.

  The present invention relates to a CVT control apparatus capable of performing more efficient shift control.

  The present invention relates to a toroidal transmission member having an input / output disk and a roller for transmitting power between the input / output disks by friction engagement between the input / output disk, and a pressing device that presses the input / output disk in a direction approaching and narrows the roller. Shifting the rotation ratio of the roller by changing the tilt angle of the roller by applying the tilting force to the roller by offsetting the rotation axis of the roller from the position where the rotation axis of the roller and the rotation axis of the input / output disk are orthogonal to each other. A toroidal CVT having a controller, and a maximum traction coefficient reduction amount estimation device for estimating a reduction amount of a maximum traction coefficient in the power transmission direction of the input / output disk and the roller that is reduced by the offset of the roller, The pressing force of the input disk is changed according to the amount of decrease estimated by the traction coefficient decrease amount estimation device. The features.

  At the time of shifting, since the roller rotation shaft is offset with respect to the disk rotation shaft, a roller tilting direction force is generated at the contact point (contact surface) between the disk and the roller. Therefore, the maximum traction coefficient in the roller rotation direction is reduced. In the present invention, the margin of the pressing force can be maintained by estimating the amount of decrease and controlling the pressing force. Therefore, even during gear shifting, the vehicle can be operated while maintaining a predetermined margin with respect to the maximum traction coefficient at that time, and it is possible to prevent the occurrence of excessive slip, to suppress efficiency deterioration, and to improve durability and reliability. it can.

  Further, the maximum traction coefficient reduction amount estimation device may estimate the reduction amount by any two of a disk rotation direction force, a roller rotation direction force, and a roller tilt direction force at a contact point between the disk and the roller. Is preferred.

  Further, the maximum traction coefficient decrease amount estimation device is configured to reduce the decrease by any two of a slip rate in the disc rotation direction, a slip rate in the roller rotation direction, and a slip rate in the roller tilt direction at the contact point between the disc and the roller. It is preferred to estimate the quantity.

  Further, the maximum traction coefficient reduction amount estimation device is configured to reduce the maximum traction coefficient reduction amount by any two of a sliding speed in the disk rotating direction, a sliding speed in the roller rotating direction, and a sliding speed in the roller tilting direction at the contact point between the disk and the roller. It is preferred to estimate the quantity.

Further, the maximum traction coefficient reduction amount estimation device determines the disk rotation direction force in the case of an input disk-roller contact point, a traction coefficient based on the slip ratio in the disk rotation direction at the contact point between the disk and the roller, and the slip ratio. Is calculated by the traction characteristics, the input disk pressing force, the tilt angle or the gear ratio (1 / speed ratio), and the roller rotation direction force is determined by the slip rate in the roller rotation direction and the traction by the slip rate. It is calculated by the traction characteristics that determine the coefficient, the pressing force of the input disk, the tilt angle or the gear ratio (1 / speed ratio), the roller tilt direction force , the slip rate in the roller tilt direction, and the slip The traction characteristics, the traction coefficient is determined by the rate, the input disk pressing force, the tilt angle or the gear ratio (1 / speed It is preferable that calculating the ratio), by.

The maximum traction coefficient reduction amount estimation device calculates the slip rate in the disc rotation direction and the slip rate in the roller rotation direction at the contact point between the disc and the roller in the case of the contact point between the input disc and the roller. In the case of the contact point between the output disk and the roller, the calculation is based on the offset amount for offsetting the roller rotation axis from the position where the roller rotation axis and the input disk rotation axis are orthogonal, and the roller rotation speed or output disk rotation speed. The rotation of the roller is calculated by the output disk rotation speed, the offset amount for offsetting the roller rotation axis from the position where the rotation axis of the roller and the rotation axis of the output disk are orthogonal, and the roller rotation speed or the input disk rotation speed. The slip rate in the rolling direction is calculated based on the input disk rotation speed and the And offset amount rotation axis La of the rotating shaft and the input disc is offset the rotation axis of the roller from a position perpendicular, calculated by the rotation speed and tilting angle or the output disk, in the case of the contact point of the output disc and roller, It is preferable to calculate based on the offset amount for offsetting the roller rotation shaft from the position where the roller rotation shaft and the output disk rotation axis are orthogonal, and the roller rotation speed and tilt angle or the input disk rotation speed and output disk rotation speed. It is.

  In addition, the maximum traction coefficient reduction amount estimation device calculates the sliding speed in the disk rotation direction and the sliding speed in the roller rotation direction at the contact point between the disk and the roller in the case of the contact point between the input disk and the roller. In the case of the contact point between the output disk and the roller, the calculation is based on the offset amount that offsets the roller rotation axis from the position where the roller rotation axis and the input / output disk rotation axis are orthogonal, and the roller rotation speed or output disk rotation speed Is calculated based on the output disk rotation speed, the offset amount for offsetting the roller rotation axis from the position where the rotation axis of the roller and the rotation axis of the output disk are orthogonal, and the roller rotation speed or the input disk rotation speed. When the sliding speed in the tilt direction is at the contact point between the input disk and the roller, the input disk rotates. In the case of the contact point between the output disk and the roller by the number, the offset amount that offsets the roller rotation axis from the position where the roller rotation axis and the input disk rotation axis are orthogonal, and the tilt angle or the output disk, the roller It is preferable to calculate based on an offset amount for offsetting the roller rotation shaft from a position where the rotation shaft of the rotation shaft and the rotation shaft of the output disk are orthogonal to each other, and the roller rotation speed and tilt angle or the input disk rotation speed and output disk rotation speed. It is.

In addition, the maximum traction coefficient reduction amount estimation device calculates the sliding speed in the disk rotation direction and the sliding speed in the roller rotation direction at the contact point between the disk and the roller in the case of the contact point between the input disk and the roller. In the case of the contact point between the output disk and the roller, the calculation is based on the offset amount that offsets the roller rotation axis from the position where the roller rotation axis and the input / output disk rotation axis are orthogonal, and the roller rotation speed or output disk rotation speed. Is calculated based on the output disk rotation speed, the offset amount for offsetting the roller rotation axis from the position where the rotation axis of the roller and the rotation axis of the output disk are orthogonal, and the roller rotation speed or the input disk rotation speed. When the sliding speed in the tilt direction is at the contact point between the input disk and the roller, the input disk rotates. In the case of the contact point between the output disk and the roller, depending on the number , the offset amount by which the roller rotation axis is offset from the position where the roller rotation axis and the input disk rotation axis are orthogonal, and the tilt angle or the output disk rotation speed. Calculating based on the offset amount for offsetting the roller rotation shaft from the position where the roller rotation shaft and the output disk rotation axis are orthogonal, and the roller rotation speed and tilt angle or the input disk rotation speed and output disk rotation speed Is preferred.

  In addition, the maximum traction coefficient decrease amount estimation device is configured to reduce the maximum traction coefficient decrease amount at the contact point between the output disk and the roller when the speed ratio is 1.0 or more. It is preferable to estimate the amount of decrease in the maximum traction coefficient at the contact point between the input disk and the roller as the amount of decrease in the maximum traction coefficient.

  Further, it is preferable that the maximum traction coefficient decrease amount estimation device estimates the decrease amount based on an offset amount for offsetting the roller rotation axis from a position where the roller rotation axis and the input disk rotation axis are orthogonal to each other.

  As described above, according to the present invention, the maximum traction coefficient in the roller rotation direction at the time of shifting estimates the amount of decrease and controls the pressing force. Therefore, even during gear shifting, the vehicle can be operated while maintaining a predetermined margin with respect to the maximum traction coefficient, so that excessive slip can be prevented, efficiency deterioration can be suppressed, and durability and reliability can be improved.

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

  FIG. 1 shows the overall configuration of the toroidal CVT according to the embodiment. That is, two sets of input disks 30a and 30b are coupled to the input shaft 10 that is rotated based on the rotation of the engine. Each of the input disks 30a and 30b has an opening formed in the center, and has a shape that gradually protrudes from the outside toward the center, and the inclined surface has a substantially arc-shaped cross section in the axial direction. Further, the input disk 30a is located on the left side in the figure, the input disk 30b is located on the right side in the figure, and both projecting centers are located so as to face the inside. The input disks 30a and 30b are arranged so that output disks 40a and 40b having substantially the same shape face each other. That is, the input disk 30a and the output disk 40a are arranged to face each other, and the input disk 30b and the output disk 40b are arranged to face each other. Accordingly, in the cross section in the axial direction, the inclined surfaces of the input disk 30a and the output disk 40a form a pair of semicircles, and the input disk 30b and the output disk 40b form another pair of semicircles.

  Rollers 35a-1 and 35a-2 are sandwiched between the input / output disks 30a and 40a, and rollers 35b-1 and 35b-2 are sandwiched between the input / output disks 30b and 40b. That is, one side of the rollers 35a-1, 35a-2, 35b-1, 35b-2 contacts the input disks 30a, 30b, the other side contacts the output disks 40a, 40b, and the rotational torque of the input disks 30a, 30b is increased. This is transmitted to the output disks 40a and 40b. The rollers 35a-1 and 35a-2 are supported by trunnions 36a-1 and 36a-2, respectively, and the rollers 35b-1 and 35b-2 are supported by trunnions 36b-1 and 36b-2, respectively. The trunnions 36a-1, 36a-2, 36b-1, and 36b-2 each have an axis in a direction perpendicular to the paper surface in the drawing, can move in the axial direction, and can rotate about the axis. ing. The radial positions of the trunnions 36a-1, 36a-2, 36b-1, and 36b-2 are fixed, and the rollers 35a-1, 35a-2, 35b-1, and 35b-2 are input and output. The discs 30a, 40a, 30b, and 40b are not separated from each other.

  The input shaft 10 is connected to a hydraulic pressure (end load) mechanism 20. The end load mechanism 20 receives hydraulic pressure inside and presses the input disks 30a and 30b toward the output disks 40a and 40b, thereby applying a narrow pressure between the input / output disks 30a and 40a and the input / output disks 30b and 40b. As a result, the rollers 35a-1, 35a-2, 35b-1, and 35b-2 are respectively sandwiched between the input / output disks 30a, 40a, 30b, and 40b with a predetermined pressure. As a result, slip between the input / output disks 30a, 40a, 30b, 40b and the rollers is prevented, and the traction state is maintained. The shaft 25 rotates in the same manner as the input shaft 10, and the input disks 30 a and 30 b are rotated by the shaft 25. The input disks 30a and 30b are connected to the shaft 25 via a thrust bearing and are movable in the axial direction of the shaft 25.

  The output disks 40a and 40b are rotatably supported on the shaft 25 via bearings. An output gear 45 is connected between the output disks 40a and 40b and rotates together with the output disks 40a and 40b. A counter gear 60 is engaged with the output gear 45, and an output shaft 70 is connected to the counter gear 60. Accordingly, the output shaft 70 rotates as the output disks 40a and 40b rotate.

  Further, the toroidal CVT is provided with a hydraulic piston chamber. The trunnions 36a-1, 36a-2, 36b-1, and 36b-2 are displaced in the trunnion axial direction by the hydraulic pressure from the hydraulic piston chamber ( Trunnion stroke: roller offset amount) is controlled. The gear ratio is changed by controlling the trunnion strokes (roller offset amounts) of the trunnions 36a-1, 36a-2, 36b-1, and 36b-2. The strokes (roller offset amounts) of the trunnions 36a-1 and 36a-2 are complementarily performed so that the line connecting the centers of the trunnions 36a-1 and 36a-2 passes through the centers of the input / output disks 30 and 40. The trunnion strokes (roller offset amounts) of the trunnions 36b-1 and 36b-2 are complementarily performed so that the line connecting the centers of the trunnions 36b-1 and 36b-2 passes through the centers of the input / output disks 30 and 40. .

  Here, the change of the gear ratio will be described with reference to FIG. FIG. 2 is a view of the input disk 30 as viewed from the output disk 40. Only one input disk 30 and one roller 35 are shown. FIG. 2A shows the case where the roller 35 is not displaced (trunion stroke = 0), and the rotational axis of the roller 35 passes through the center of the input disk 30. That is, the rotation axis of the roller is orthogonal to the rotation axis of the disk.

  When shifting, the trunnion 36 is offset in the axial direction. For example, as shown in FIG. 2B, the input disk 30 is offset in the rotating direction (upper side in the figure). That is, the rotation axis of the roller is offset to a position that is not orthogonal to the rotation axis of the disk. As a result, the roller 35 receives a force in the circumferential direction of the input disk 30 at the moved position, and the roller 35 receives a force (tilting force) that moves to the peripheral side of the input disk 30. When the offset amount (trunion stroke) of the roller 35 returns to 0, the position of the roller 35 that contacts the input disk 30 is displaced outward in the radial direction. As a result, the contact position of the roller 35 with the output disk 40 is displaced radially inward, and the gear ratio is changed (upshifted). It should be noted that the trunnion 36 is tilted in the opposite direction by down-shifting by offsetting the trunnion 36 in the downward direction (the side from which the input disk moves away) in the figure.

  Here, in this embodiment, the amount of decrease in the maximum traction coefficient at the time of shifting is estimated. The definition and estimation method of the reduction amount (DRμmax) of the maximum traction coefficient will be described below.

“Estimation of DRμmax by force acting on contact point”
FIG. 3 is the same as the diagram on the right side of FIG. 2 and shows only the input disk and one roller. In the following description, the suffix “i” of the parameter name indicates the input disk side, and the suffix “o” indicates the output disk side.

  When the rotation center axis of the input disk 30 and the rotation center axis of the roller are offset from each other, the force acting on the roller 35 from the input disk 30 at the contact point (strictly, the position of the center of gravity of the contact surface) It acts as a disk rotation direction force Fdi having an angle with the tilt direction.

  Therefore, the driving force Fti that is the rotation direction and the tilting force Fθi orthogonal to the driving force Fti are applied to the roller 35. For this reason, the maximum traction coefficient of the contact surface in the roller rotation direction (the maximum transmission force for a certain pressing force is defined) is smaller than the maximum traction coefficient in a state where the offset is zero. That is, the maximum traction coefficient is reduced by the ratio of the magnitude of the disk rotation direction force Fdi and the driving force Fti shown in FIG.

  Further, since the remaining one is determined by two of the disk rotation direction force Fdi, the roller tilting force Fθi, and the driving force Fti, the reduction rate of the maximum traction coefficient is the disk rotation direction force Fdi, the roller It can also be expressed by the ratio of the magnitude of the tilting force Fθi or the ratio of the magnitude of the driving force Fti and the roller tilting force Fθi. Therefore, the reduction rate DRμmax of the maximum traction coefficient (μmax) at the contact point of the input disk 30 can be expressed by the equation (1). The same applies to the output disk side.

  Considering the contact point of the input disk 30, the disk rotation direction force Fdi can be expressed by equation (2) by the traction coefficient μi of the contact point and the normal force Fci of the contact point.

    Fdi = μi (Sdi) Fci (2)

  Here, as represented by the traction characteristics in FIG. 4, the traction coefficient μ rises with a slope Δμ as the slip ratio Sd increases, reaches a peak immediately before reaching μmax, and reaches a maximum at μmax. Then gradually decrease. The slip ratio Sdi is the slip ratio in the disk rotation direction at the input disk contact point, and can be expressed by the equation (3).

  Here, ri: input disk contact point rotation radius, ωi: input disk rotation speed, ωr: roller rotation speed, Rr: roller rotation radius, ηi: straight input disk connecting the center of the input disk and the roller oscillation center An angle (see FIG. 3) measured clockwise from a specified direction (in the figure, a direction facing downward from the center), xi: an input disk contact point offset amount.

  Similarly, the driving force Fti at the input disk contact point, the tilting force Fθi, the slip rate St in the direction of the driving force, and the slip rate Sθ in the direction of the tilting force can be expressed by equations (4) to (7).

  Here, ri: contact point disk rotation radius, ωi: disk rotation speed, ωr: roller rotation speed, Rr: contact point roller rotation radius, ηi: see FIG. 3, Θ: contact with the input disk as seen from the roller oscillation center ½ of the angle of the point and the contact point with the output disk, that is, the half apex angle (see FIG. 5), θ: tilt angle, Ro: cavity radius (distance from roller tilt center to contact point), Fc : Disc pressing force.

  Further, when the input torque is used, the driving force Fti can also be expressed by equation (8).

  Here, Ti: disk input torque, Te: engine torque, Je: moment of inertia of the input section, and nr: total number of rollers.

  Further, the disk pressing force Fci can be expressed by equation (9), and the contact point disk rotation radius ri can be expressed by equation (10).

  Here, Fai: input disk pressing force, nrc: number of rollers in the cavity, Se: hydraulic piston pressure receiving area, Pe: piston hydraulic pressure, Eo: distance from the input shaft to the spherical surface defined by the input / output disk (see FIG. 5) ).

  From the above formulas (2) to (10), DRμmax of the contact point of the input disk at the time of shifting (offset xi ≠ 0) can be estimated from the formula (1).

  Similarly, DRμmax at the contact point of the output disk can also be estimated by the following equations (11) to (18).

  Here, ro: output disk contact point rotation radius, ωo: output disk rotation speed, ηo: as in FIG. 3, xo: output disk contact point offset amount, Fco: normal force at the output disk side contact point, Fao: output Disk pressing force, nrc: the number of rollers in the cavity.

  The dxi / dt and dxo / dt in the expressions (3), (5), (12), (14), and (16) may be directly observed or differentiated (differentiated) xi and xo, but their influence May be ignored (removed from each equation).

  In the equations (3), (5), (7), (8), (12), (14), and (16), ωi, ωo, xi, and xo are directly measured, and ωr and θ are directly measured. If not, it can be estimated (approximate) as follows.

  Here, f is a function obtained by geometrically determining the relationship between the speed ratio ωo / ωi and the tilt angle, and is represented as shown in FIG. 6, for example.

  Dθ / dt (θ dot in the equation) may be a time difference between measured θ and θ estimated by equation (12), but may be estimated by using the following approximate equation. This approximate expression will be described later.

  If the offsets xi and xo of the input / output disks cannot be measured directly, they can be estimated as follows from the geometric relationship shown in FIG. That is, FIG. 7 shows the case of the input disk, where the offset amount of the rotation center of the roller is x, the contact point rotation radius ri of the input disk, and the cavity radius (the distance from the center of oscillation of the roller to the contact point). When Ro is the distance from the rotation center of the input disk to the lowest point of the input disk (the distance from the rotation center of the input disk to the rocking center of the roller minus the cavity radius Ro) Eo, the following relationship is established: is there.

  From the above results, the pressing force Fci required to maintain a certain margin with respect to the maximum traction coefficient μmax is the decrease rate DRμmax of the maximum traction coefficient at the contact point of the input disk and DRμmax of the contact point of the output disk. The larger one should be used. When this larger one is replaced with DRμmax again, Fci0 can express the pressing force required in the steady state (xi = xo = 0) by the equation (24).

  Also, it can be seen from the relationship between the forces acting on the contact points shown in FIG. 3 that DRμmax increases as the contact point offset amount increases, so the input / output disk contact point rotation radius ri from the relationship of equations (22) and (23). It is presumed that DR μmax is larger when RO is larger. In other words, it is presumed that the DRμmax on the input side increases on the speed increasing side (gear ratio γ <0) and the DRμmax on the output side increases on the deceleration side (γ ≧ 0).

  Therefore, it is possible to estimate DRμmax by calculating only one of the estimations obtained by detecting whether the speed is on the acceleration side or the deceleration side without obtaining the DRμmax on the input side and the output side and comparing them. .

“Estimation of DRμmax by slip rate”
Next, a method for estimating DRμmax by the slip ratio will be described. The input traction coefficient μi in the above equations (2), (4), and (6) and the output traction coefficient μo in the equations (11), (13), and (15) represent the traction curves shown in FIG. However, under actual use conditions, the vehicle is operated with a certain margin with respect to μmax in order to ensure safety and reliability. Further, the relationship between the traction coefficient (μi, μo) up to μmax and the slip rate can be regarded as almost linear as shown by Δμ in FIG. Accordingly, assuming that the traction characteristics at the contact point are the same regardless of the slip direction, and the change rates (gradients) are Δμi and Δμo, (2), (4), (6), (11), (13 ), (15) can be expressed by equations (25)-(30).

  Therefore, DRμmax that can be estimated by any two of Fdi, Fti, and Fθi can be expressed by equations (25), (26), and (27). Considering that Δμi and Fci are common, it can be estimated by the following equation (31) using any two of the slip ratios Sdi, Sti, Sθi. The same applies to the output disk side (the parameter name may be changed from “i” to “o”).

  Furthermore, since Sdi, Sti, and Sθi have the same denominator as represented by the equations (3), (5), and (7), DRμmax is the numerator of the equations (3), (5), and (7). That is, it can be expressed by a ratio of sliding speed. That is, it can be estimated by equation (32). The same applies to the output disk side (the parameter name may be changed from “i” to “o”).

  However, Vdi, Vti, and Vθi are as follows.

  FIG. 8 shows an example in which the μmax reduction rate DRμmax is estimated. In this example, the driving force ((2) on the input disk side is calculated based on the data when the speed is changed from 2.0 to 1.0 at a speed ratio of 2.0 to 1.0 with a toroidal CVT test box at a constant input torque of 100 Nm and an output speed of 2000 rpm. , (3)) and the tilting force ((6), (7)) were calculated, and DRμmax was estimated using equation (1). It can be seen that DRμmax reaches its maximum after a time of 0.2 seconds immediately after the shift, and the μmax decreases by about 0.3, that is, about 30%.

  Therefore, it can be seen that it is necessary to increase the pressing force by about 30% in order to keep the margin for μmax constant in this state. Conversely, if the margin is set to less than 30% in this state and control is performed with the same pressing force as before shifting, there is a possibility of slipping. By estimating DRμmax and controlling the pressing force according to the estimated value, the reliability and durability of the toroidal CVT can be improved.

  That is, at the time of shifting, since the roller rotation shaft has an offset with respect to the disk rotation center axis, a roller tilt direction force is generated at the contact point (contact surface) between the disk and the roller. For this reason, the maximum traction coefficient in the drive direction, that is, the roller rotation direction is lower than that in the disk rotation direction, that is, the margin for the maximum traction coefficient is reduced. The amount of decrease is estimated to control the pressing force. Thus, the margin can be kept constant. Therefore, even during gear shifting, it is possible to operate with a certain margin with respect to the maximum traction coefficient, to prevent excessive slip, to suppress efficiency deterioration, and to improve durability and reliability. it can.

  FIG. 9 shows a configuration example of the CVT that calculates the maximum traction coefficient and controls the pressing force (end load). The necessary pressing force Fci0 determined according to the input torque, the gear ratio, etc. is input to the hydraulic pressure calculation unit 80. The hydraulic pressure calculation unit 80 is supplied with the maximum traction coefficient decrease amount DRμmax that is calculated in the maximum traction coefficient calculation unit (DRμmax calculation unit) 82 and that changes during a shift. Therefore, in the hydraulic pressure calculation unit 80, the end load set value is corrected by DRμmax (Fci = Fci0 / DRμmax), the pressure control valve 84 is controlled by the obtained pressing force control value Fci, and the pressing force in the toroidal CVT 110 is controlled. To do.

  Further, the target tilt angle is input to the adder 102. The adder 102 feeds back the current tilt angle θ obtained by measurement, and the adder 102 calculates and outputs the difference (deviation) between the two. The output of the adder 102 is supplied to a feedback gain multiplication circuit 104, where it is multiplied by a predetermined feedback gain and then supplied to a flow control valve 108 that controls the hydraulic pressure of the trunnion hydraulic device. This flow control valve 108 controls the trunnion stroke of the toroidal CVT 110, whereby the trunnion stroke x is controlled, and the tilt angle θ of the roller is controlled. Further, the output disk rotational speed ωo is also controlled according to the tilt angle θ.

  Further, in the present embodiment, the trunnion stroke x, the tilt angle θ, and the output disk rotational speed ωo in the toroidal CVT 110 are supplied to the tilt angular velocity approximation formula circuit 112. The tilt angular velocity approximate expression circuit 112 calculates the tilt angular velocity dθ / dt (θ dot) by the above-described equation (24) based on the supplied x, θ, and ω, and supplies this to the DRμmax calculation unit 82. Supply. Therefore, the DRμmax calculation unit 82 can calculate DRμmax using the tilt angular velocity supplied from the tilt angular velocity approximate expression circuit 112.

"Estimation of tilt angular velocity"
Next, estimation of the tilt angular velocity of the above equation (21) will be described.

  The configuration of the toroidal CVT considered here is the same as that described above, as shown in FIG. The estimation of the tilt angular velocity in such a toroidal CVT will be described below.

  The equation of motion in the direction of tilting (transmission) of the trunnion is as shown in equation (41) by considering the relationship between the disc rotational direction force Fdi and the tilting force Fθi shown in FIG. 3 and the rotational moment around the trunnion center in FIG. Call.

  Here, Fθi: input side tilting force, Fθo: output side tilting force, Fdi: input side disk rotation direction force, Fdo: output side disk direction rotation force, Fa: end load (clamping pressure), nrc: number of rollers / Cavity, Sci: input side tilt direction slip ratio, Sco: output side tilt direction slip ratio, μi: input side traction coefficient, μo: output side traction coefficient, R0: cavity radius, Θ: half apex angle, θ: Tilt angle.

  Since the normal force at the contact point is the same as Fci = Fco = Fa / (nrc · sin (Θ + θ)) for both input and output, it can be expressed by equation (42).

  In this equation, I: very small (≈0), μi≈μo, and the traction coefficient in the actual use range can be expressed linearly as shown in FIG.

That means
μi (Sci) ≈ΔμSci, μo (Sco) ≈ΔμSco (43) Assuming that (42)
Δμ (Sci + Sco) = 0 ⇒ Sci + Sco = 0 (44) Here, the slip ratios Sci and Sco on the input / output side tilt direction can be expressed by equations (45) and (46), respectively.

  Here, ri: input side contact point radius, ro: output side contact point radius, ωi: input side disk angular velocity, ωo: output side disk angular velocity, Rr: roller rotation radius (= R0sin θ).

  Further, when Expressions (45) and (46) are substituted into Expression (44) and expanded as follows, Expression (7) can be derived.

Assuming that the slip at the input / output contact point is very small, riωi≈roωo≈Rrωr.
It can be expressed as

  Further, as shown in FIG. 7, when considering a plane passing through the contact point and orthogonal to the disc rotation axis, the stroke of the contact point between the disc and the roller can be expressed by the equation (48) by the trunnion stroke.

  Further, sin ηi and sin ηo are expressed by equation (49) from the relationship shown in FIG.

Substituting the equations (48) and (49) into the equation (47), the equation (50)
From sin (Θ + θ) + sin (Θ−θ) = 2 sinΘ cos θ, a tilt angle approximation can be derived as shown in equation (51). This equation (51) is the same as the above-mentioned (21).

  FIG. 10 shows the result of verifying the tilt angular velocity derived from the equation (51) with actual data. It can be seen that the actual tilt angle difference agrees well with that of the prior art.

  The following state quantities can be estimated by using the tilt angular velocity θ derived by the equation (51).

(I) Slip speed and slip rate of the contact point between the input / output disk and the roller in the direction of the trunnion tilting The slip rate can be obtained by substituting Equation (51) into Equations (45) and (46). The sliding speed is a molecule of the formulas (5) and (6).

(Ii) Traction coefficient in the direction of tilting the trunnion, traction force From the slip ratio derived from (i), the traction coefficient can be derived by using equation (43).

  Further, when the derived traction coefficient is multiplied by the normal force of the contact surface, that is, Fa / (nrc · sin (Θ + θ)), the traction force in the tilt direction is obtained.

(Iii) Rotational angular velocity of input disk and roller The relationship between the tilt angle θ and the gear ratio (ωi / ωo) can be expressed as a formula (52) by a polynomial (for example, second order) as shown in FIG. it can.

When this equation (52) is time differentiated,
It becomes. Here, assuming that the slip between the disk and the roller is very small, the equation (54) is satisfied.

  Then, assuming that the change in ωo is sufficiently smaller than ωi (ωo constant), the equation (54) is time-differentiated to obtain the equation (55).

  If the equation (51) is substituted into the θ dot of the equation (55), ωi can be estimated without obtaining the derivative of the tilt angle θ.

  Further, when the rotational inertia of the input unit is multiplied by the equation (55), the rotational inertia force can be estimated, and the engine rotational inertia torque during the shift transition is greatly affected by the detection accuracy of the rotational speed sensor and the noise included in the rotational speed signal. It is possible to derive without using the rotational speed difference.

  In addition, it is known that using a trunnion stroke as a feedback amount for shift control is effective for shifting stability, but a trunnion tilt angular velocity is also effective. However, in reality, the tilt angle must be differentiated and it is difficult to actually control the detection accuracy.

  In addition, the trunnion stroke maintains stability by controlling it to the zero position where tilting force does not occur, but the zero point changes depending on the operating conditions, so the zero point may shift, and as a result, the gear ratio is offset. Will have.

  Therefore, if equation (51) is used, the tilt angular velocity of the trunnion can be calculated without the need for a differential operation, so that the shift ratio offset is suppressed without being affected by the problem of the zero point of the trunnion stroke while ensuring the shift stability. Can do.

  In other words, the tilt angle signal measured using a practical tilt angle sensor has a resolution and large noise, so that even if the tilt angular velocity is calculated by differentiation (difference), the actual tilt angular velocity is large. Deviations and vibrations due to discrete signals. However, in the approximate expression, the tilt angular velocity can be calculated only from the tilt angle, rotation speed, and stroke signals, and a differential (difference) signal is not required, so that the accuracy can be relatively improved. According to this embodiment, since the tilt angular velocity can be accurately estimated without differentiating (differing) the tilt angle, the estimation accuracy is improved in the estimation that requires the tilt angular velocity, and the tilt angular velocity is used. In the toroidal CVT shift control, the control performance can be improved.

  FIG. 12 illustrates a configuration in which the tilt angular velocity detection method according to this embodiment is applied to tilt angle control. The target tilt angle is input to the adder 102. The adder 102 feeds back the current tilt angle θ obtained by measurement, and the adder 102 calculates and outputs the difference (deviation) between the two. The output of the adder 102 is supplied to a feedback gain multiplication circuit 104, where a predetermined feedback gain is multiplied, and then supplied to an adder 106. The adder 106 is supplied with a feedback value for a tilt angular velocity described later, and the adder 106 subtracts a feedback value for the tilt angular velocity.

  The output of the adder 106 is supplied to a flow control valve 108 that controls the hydraulic pressure of the trunnion hydraulic device. This flow control valve 108 controls the trunnion stroke of the toroidal CVT 110, whereby the trunnion stroke x is controlled, and the tilt angle θ of the roller is controlled. Further, the output disk rotational speed ωo is also controlled according to the tilt angle θ.

  Then, the trunnion stroke x, the tilt angle θ, and the output disk rotational speed ωo in the toroidal CVT 110 are supplied to the tilt angular velocity approximation formula circuit 112. The tilt angular velocity approximation formula circuit 112 calculates the tilt angular velocity dθ / dt (θ dots) by the above-described formula (51) based on the supplied x, θ, and ω, and supplies it to the feedback gain multiplication circuit 114. To do. The feedback gain multiplication circuit 114 multiplies the tilt angular velocity by a predetermined feedback gain and supplies the result to the adder 106 as a negative value.

  As described above, according to the configuration of FIG. 12, the tilt angle θ and the tilt angular velocity dθ / dt are fed back, and the tilt angle in the toroidal CVT 110 is controlled to coincide with the target tilt angle. In particular, the calculation of the tilt angular velocity dθ / dt is not based on the time change of the measured value of the tilt angle θ, but is calculated from the measured value using the formula (51). Therefore, it is possible to calculate a tilt angular velocity with a small error without taking time, and to perform control with higher accuracy.

  Next, in FIG. 13, instead of measuring the tilt angle θ, the input / output disk rotational speeds ωi and ωo are measured. The measured ωi and ωo are supplied to the tilt angle calculation circuit 116. The tilt angle calculation circuit 116 calculates and calculates the relationship tilt angle θ between the gear ratio ωi / ωo and the tilt angle shown in FIG. 8 and supplies this to the tilt angular velocity approximate expression circuit 112.

  The other points are the same as in the configuration of FIG. 12, and effective tilt angle control is performed using the tilt angular velocity approximation formula (51).

  Further, as shown in FIG. 14, the tilt angular velocity of equation (51) is used as a feedback amount and a target value of the tilt angular velocity is set, and the deviation between the target value and the tilt angular velocity of equation (11) is fed back. By doing so, the responsiveness can be improved as compared with the control system that feeds back the deviation between the target tilt angle and the tilt angle.

  That is, the target tilt angular velocity is supplied to the adder 118, and the deviation from the tilt angular velocity dθ / dt supplied from the tilt angular velocity approximate expression circuit 112 is obtained here. The tilt angular velocity deviation is multiplied by the feedback gain in the feedback gain multiplication circuit 120 and then supplied to the adder 106 as a positive value. Thereby, feedback control of the tilt angular velocity itself is additionally performed.

  14, in the configuration of FIG. 14, as in FIG. 13, instead of measuring the tilt angle θ, the input / output disk rotational speeds ωi and ωo are measured, and the tilt angle calculation circuit 116 is operated by the tilt angle calculation circuit 116. In this configuration, θ is calculated and supplied to the tilt angular velocity approximate expression circuit 112.

  In the configuration of FIG. 16, instead of feeding back the feedback tilt angular velocity from the tilt angular velocity approximating circuit 112 to the adder 106, the feedback gain multiplication circuit 124 multiplies the feedback gain by the feedback gain multiplication circuit 124 to add the trunnion stroke x. Feedback to the device 106. As a result, the feedback control based on the deviation of the target tilt angle and the target tilt angular velocity can be further corrected by the trunnion stroke x.

  FIG. 17 is a combination of the configuration of FIG. 9 and the configuration of FIG. 12, and dθ / dt, which is the output of the tilt angular velocity approximation formula circuit 112, is applied to both the DRμmax calculation unit 82 and the feedback gain multiplication circuit 114. Supplied. With this configuration, it is possible to control the pressing force in consideration of a decrease in the maximum traction coefficient during a shift, and it is possible to control the tilt angle by feeding back the tilt angular velocity to the tilt angular velocity.

  Furthermore, it is also suitable to combine the structure of FIG. 9 with the structure of FIGS.

(Configuration suitable for tilt angular velocity detection)
In order to detect the tilt angular velocity, the following configuration is suitable.

  A toroidal transmission member having an input / output disk and a roller for transmitting power between the input / output disks by frictional engagement between the input / output disk, a pressing device that presses the input / output disk in a direction approaching and narrows the roller, and rotation of the roller A shift control unit that controls the transmission ratio by changing the tilt angle of the roller by applying a tilting force to the roller by offsetting the rotation shaft of the roller from a position where the shaft and the rotation axis of the input / output disk are orthogonal to each other. In the toroidal CVT, the offset amount of the roller rotation shaft, the input disk rotation speed, the roller rotation speed, and the output disk rotation speed, and at least one of the tilt angle and the gear ratio. It is preferable to have a tilt angular velocity estimation device that estimates a tilt angular velocity based on one of them.

  When the tilt angle is measured by using the tilt angle sensor, the system of the tilt angular velocity obtained by differentiating the difference is deteriorated due to its resolution and noise, and it becomes oscillating because of a discrete signal. According to the approximate expression of the present invention, the tilt angular velocity can be calculated from the measured tilt angle, rotation speed, and stroke signal, and no differentiation (difference) calculation is required. For this reason, it is possible to raise the accuracy relatively. And it becomes possible to improve the shift control performance in toroidal CVT using the tilt angular velocity obtained in this way.

  In addition, it is preferable to estimate at least one of a sliding speed, a sliding ratio, a traction coefficient, or a traction force at a contact point between the input / output disk and the roller based on the tilting angular speed estimated by the tilting angular speed estimation device.

  Moreover, it is preferable to estimate the rotational angular acceleration of the input disk or the respective rotational inertial forces based on the tilt angular velocity estimated by the tilt angular velocity estimation device.

  In addition, it is preferable that the tilt angular velocity estimated by the tilt angular velocity estimating device and any one of the tilt angle and the gear ratio be used as a feedback amount.

  In addition, it is preferable that the tilt angular velocity estimated by the tilt angular velocity estimating device is used to follow the target tilt angular velocity.

It is a figure which shows the structure of the toroidal type CVT of embodiment. It is a figure which shows the speed change mechanism. It is a figure explaining the force which acts between roller discs. It is a figure which shows the relationship between a slip ratio and a traction coefficient. It is a figure which shows the tilt angle etc. of a roller. It is a figure which shows the relationship between a speed ratio and a tilt angle. It is a figure explaining the offset amount of a roller. It is a figure explaining the fall of the maximum traction coefficient, etc. in the case of changing a gear ratio. It is a figure which shows the structure for the control which considered the fall of the maximum traction coefficient. It is a figure which shows the calculation result of inclination angular velocity. It is a figure which shows the relationship between a tilt angle and a gear ratio. It is a block diagram which shows the structural example of tilt angle control. It is a block diagram which shows the other structural example of tilt angle control. It is a block diagram which shows the further another structural example of tilt angle control. It is a block diagram which shows the further another structural example of tilt angle control. It is a block diagram which shows the further another structural example of tilt angle control. It is a figure which shows the structure which performs the tilt angle control while considering the fall of the maximum traction coefficient.

Explanation of symbols

  10 input shaft, 20 end load mechanism, 30 (30a, 30b) input disk, 35 (35a-1, 35a-2, 35b-1, 35b-2) roller, 36 (36a-1, 36a-2, 36b-) 1, 36b-2) trunnion, 40 (40a, 40b) output disk, 45 output gear, 60 counter gear, 70 output shaft, 82 maximum traction coefficient calculator, 102, 106, 118 adder, 104 feedback gain multiplication circuit, 108 flow control valve, 112 tilt angular velocity approximation formula circuit, 114, 120, 122 feedback gain multiplication circuit, 116 tilt angle calculation circuit.

Claims (10)

A toroidal transmission member having an input / output disk and a roller for transmitting power between the input / output disks by frictional engagement between the input / output disk, a pressing device that presses the input / output disk in a direction approaching and narrows the roller, and rotation of the roller A shift control unit for controlling the transmission ratio by changing the tilt angle of the roller by applying a tilting force to the roller by offsetting the rotation shaft of the roller from a position where the shaft and the rotation axis of the input / output disk are orthogonal to each other; Toroidal CVT having
A maximum traction coefficient reduction amount estimating device for estimating a reduction amount of the maximum traction coefficient in the power transmission direction of the input / output disk and the roller, which is reduced by the offset of the roller;
Changing the pressing force of the input disk according to the amount of decrease estimated by the maximum traction coefficient decrease amount estimating device;
A toroidal CVT control device. The apparatus of claim 1.
The maximum traction coefficient decrease amount estimation device estimates the decrease amount by any two of a disk rotation direction force, a roller rotation direction force, and a roller tilt direction force at a contact point between the disk and the roller,
A toroidal CVT control device. The apparatus of claim 1.
The maximum traction coefficient reduction amount estimation device calculates the reduction amount by any two of a slip rate in the disc rotation direction, a slip rate in the roller rotation direction, and a slip rate in the roller tilt direction at the contact point between the disc and the roller. presume,
A toroidal CVT control device. The apparatus of claim 1.
The maximum traction coefficient reduction amount estimation device calculates the reduction amount by any two of a sliding speed in the disk rotation direction, a sliding speed in the roller rotation direction, and a sliding speed in the roller tilt direction at the contact point between the disk and the roller. presume,
A toroidal CVT control device. The apparatus of claim 2.
The maximum traction coefficient decrease amount estimation device is:
When the disk rotation direction force is the contact point between the input disk and the roller, the slip rate in the disk rotation direction at the contact point between the disk and the roller, the traction characteristic whose traction coefficient is determined by the slip rate, and the pressing force of the input disk , Calculated by the tilt angle or gear ratio,
The roller rotation direction force is calculated by the slip ratio in the roller rotation direction, the traction characteristic whose traction coefficient is determined by the slip ratio, the pressing force of the input disk, the tilt angle or the gear ratio,
The roller tilt direction force is calculated by a slip rate in the roller tilt direction, a traction characteristic whose traction coefficient is determined by the slip rate, a pressing force of the input disk, and a tilt angle or a gear ratio.
A toroidal CVT control device. The apparatus of claim 3.
The maximum traction coefficient decrease amount estimation device is:
The slip rate in the disc rotation direction and the slip rate in the roller rotation direction at the contact point between the disc and the roller are as follows. Calculated by the offset amount that offsets the rotation axis of the roller from the orthogonal position and the rotation speed of the roller or the output disk, and in the case of the contact point between the output disk and the roller, the output disk rotation speed and the roller rotation axis And the offset amount for offsetting the rotation axis of the roller from the position where the rotation axis of the output disk and the output disk are orthogonal to each other, and the rotation speed of the roller or the input disk rotation speed,
When the slip rate in the roller tilt direction is the contact point between the input disk and the roller, the amount of offset that offsets the roller rotation axis from the position where the input disk rotation speed and the rotation axis of the roller intersect the rotation axis of the input disk. If, calculated by the tilt angle or the output disk rotation speed, in the case of the contact point of the output disc and roller, the offset amount of the axis of rotation of the output disk and the rotary shaft of the roller is offset the rotation axis of the roller from a position perpendicular And calculating by roller rotation speed and tilt angle or input disk rotation speed and output disk rotation speed,
A toroidal CVT control device. The apparatus according to claim 4 .
The maximum traction coefficient decrease amount estimation device is:
The disk rotation speed and the roller rotation speed at the contact point of the disk and roller are the input disk rotation speed, roller rotation axis, and input / output disk rotation axis for the input disk and roller contact point. Is calculated by the offset amount that offsets the rotation axis of the roller from the position at which they are orthogonal, and the roller rotation speed or output disk rotation speed. In the case of the contact point between the output disk and the roller, the output disk rotation speed and the roller rotation Calculate by the offset amount that offsets the rotation axis of the roller from the position where the shaft and the rotation axis of the output disk are orthogonal, and the roller rotation speed or the input disk rotation speed,
When the sliding speed in the roller tilt direction is the contact point between the input disk and the roller, the offset amount that offsets the rotation axis of the roller from the position where the rotation speed of the input disk and the rotation axis of the roller intersect the rotation axis of the input disk. And an offset amount for offsetting the rotation axis of the roller from a position where the rotation axis of the roller and the rotation axis of the output disk are orthogonal to each other at the contact point of the output disk and the roller according to the tilt angle or the output disk rotation speed , Calculate based on the roller rotation speed and tilt angle or the input disk rotation speed and output disk rotation speed.
A toroidal CVT control device. The device according to claim 1,
The maximum traction coefficient decrease amount estimation device is configured such that the maximum traction coefficient decrease amount at the input disk / roller contact point and the maximum traction coefficient decrease amount at the output disk / roller contact point is the larger maximum traction coefficient decrease amount. To
A toroidal CVT control device. The device according to claim 1,
The maximum traction coefficient decrease amount estimation device increases the decrease amount of the maximum traction coefficient at the contact point between the output disk and the roller at a speed ratio of less than 1.0 at the time of deceleration with a speed ratio of 1.0 or more. In some cases, the amount of decrease in the maximum traction coefficient at the contact point between the input disk and the roller is estimated as the amount of decrease in the maximum traction coefficient.
A toroidal CVT control device. The apparatus of claim 1.
The maximum traction coefficient decrease amount estimation device estimates the decrease amount by an offset amount that offsets the roller rotation axis from a position where the roller rotation axis and the input disk rotation axis are orthogonal to each other.
A toroidal CVT control device.