JP4198937B2 - Toroidal CVT shift control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a toroidal conductive 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, and a position where the rotation axis of the roller and the rotation axis of the input / output disk are orthogonal to each other. Thus, the present invention relates to a toroidal CVT shift control device having a shift control unit that changes the tilt angle of the roller by offsetting the rotation shaft of the roller and controls the gear ratio.
[0002]
[Prior art]
Conventionally, various types of continuously variable transmissions (CVTs) are known, including a toroidal CVT. This toroidal CVT has an input / output disk and a roller for transmitting power between the input / output disk by frictional engagement in the middle.
[0003]
The input / output disk as a whole has a shape close to a triangular pyramid, and its slope is cut into an arc shape. The input / output discs are arranged so that the protruding central portions face each other, and the cross section of the input / output discs combined is cut into a semicircle from both sides. Therefore, the roller contacts the peripheral side of the input disk and the inner side of the output disk, so that the rotation of the part away from the axis of the input disk can be transmitted to the side close to the axis of the output disk and the reduction ratio is small Thus, the gear ratio can be determined by changing the contact position.
[0004]
The roller is supported by a member called a trunnion so that it can rotate and the position of contact with the input / output disk can be changed. The rotation angle around the axis of the trunnion is inclined (inclined) with respect to the input / output disk. In the toroidal CVT, the gear ratio is determined by the tilt angle.
[0005]
Further, when changing the tilt angle, the trunnion is moved in a direction perpendicular to the input / output disk rotation axis. That is, the rotation axis of the roller is offset from a position where the rotation axis of the roller and the rotation axis of the input / output disk are orthogonal to each other. This offset amount is called a trunnion stroke. As a result, a force in the direction of changing the tilt angle is applied to the roller, thereby changing the tilt angle of the roller and controlling the transmission ratio.
[0006]
Therefore, in the toroidal CVT, the tilt angle, which is the rotation angle around the trunnion axis of the roller supported by the trunnion, and the offset amount (trunnion stroke) in the axial direction of the trunnion are detected. Then, a gear ratio is obtained from the tilt angle, and a target position displacement (offset amount = trunion stroke) of the roller in the trunnion axis direction is calculated based on a deviation between the gear ratio and the target gear ratio. Then, the trunnion is displaced by the hydraulic actuator so that the trunnion stroke (offset amount) matches the target trunnion stroke (offset amount). Thus, the gear ratio control is performed by controlling the offset amount from the deviation of the tilt angle (speed ratio) from the target. Note that performing such control as electronic feedback control is disclosed in Japanese Patent Application Laid-Open No. 08-233085.
[0007]
[Problems to be solved by the invention]
As described above, the gear ratio control in the toroidal CVT is performed. This control controls the tilt angle by controlling the offset amount, and the control is relatively complicated. Further, since the offset amount is usually performed by hydraulic pressure and is controlled by controlling the hydraulic control valve, it is difficult to accurately control the whole. For example, the frequency response from the toroidal CVT hydraulic control valve command value to the tilt angle or trunnion stroke (offset amount) varies depending on the input torque of the transmission. For this reason, there is a problem that appropriate control cannot be performed unless the control is changed in accordance with a change in input torque.
[0008]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a transmission control device for a toroidal CVT capable of appropriately controlling a transmission gear ratio.
[0009]
[Means for Solving the Problems]
The present invention relates to a toroidal conductive 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 an input / output disk for controlling the pressing force of the input / output disk by hydraulic pressure. A pressure control unit, and a transmission control unit that controls the transmission ratio by changing the tilt angle of the roller by offsetting the rotational axis of the roller from a position where the rotational axis of the roller and the rotational axis of the input / output disk are orthogonal A toroidal CVT having a feedback control unit that feeds back a roller tilt angle and the roller rotation shaft offset amount, and at least one of the roller tilt angle and the roller rotation shaft offset amount. the feedback gain, the input and output disks pressing force, and one of the roller tilt angle Contact and input speed, And changes based.
[0010]
Thus, according to the present invention, the feedback gain of the roller tilt angle or the roller rotation axis offset amount is changed according to the operating conditions. As a result, gear ratio control can be performed with an appropriate feedback gain under the driving conditions at that time, and the shift response and stability can be kept constant.
[0011]
Also, changing the the roller tilt angle, the feedback gain for each of the roller rotation axis offset amount, and the input and output disks pressing force, and one of the roller tilt angle Contact and input speed, on the basis It is preferable to do. Thereby, more appropriate control can be performed.
[0012]
The roller tilt angle is preferably detected by a roller tilt angle or a gear ratio.
[0013]
Further, with respect to the feedback gain for at least one of the roller tilt angle and the roller rotation axis offset amount, the input / output disk pressing force, the roller tilt angle, and any one of the input rotation speeds It is preferable that the relationship is stored in advance, and the feedback gain is determined using the stored relationship.
[0014]
The roller rotation shaft offset amount is preferably detected by any one of a roller rotation shaft offset amount, a roller tilt angle change amount, a gear ratio change amount, and an input rotation speed change amount.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
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.
[0017]
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.
[0018]
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.
[0019]
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.
[0020]
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. .
[0021]
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. 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). 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.
[0022]
FIG. 3 shows a configuration for this gear ratio control. In FIG. 3, one input disk 30, two rollers 35-1, 35-2, and two trunnions 36-1, 36-2 are shown.
[0023]
Thus, the hydraulic piston chamber 50 has a pair of piston chambers 50-1 and 50-2 in order to make the trunnions 36-1 and 36-2 operate in a complementary manner. A hydraulic control valve 52 is connected to the piston chambers 50-1 and 50-2, and the hydraulic pressure supplied to the hydraulic piston chambers 50-1 and 50-2 is controlled by the control of the hydraulic control valve 52. The strokes (roller offset amounts) of the trunnions 36-1 and 36-2 are controlled.
[0024]
Then, the tilt angle θ of the trunnion 36 is detected by the tilt angle sensor 37, and the stroke x is detected by the stroke sensor 38 and supplied to the controller 80.
[0025]
The controller 80 is also supplied with information about the accelerator opening and the vehicle speed. The controller 80 determines a target gear ratio from the accelerator opening and the vehicle speed, and the tilt detected by the target gear ratio and the tilt angle sensor 37 is determined. The target stroke is determined based on the deviation from the gear ratio corresponding to the turning angle θ. Based on this target stroke, the hydraulic control valve 52 is controlled to control the stroke x of the trunnion 36. As a result, the gear ratio at that time obtained from the tilt angle coincides with the target gear ratio, and the gear ratio control is terminated.
[0026]
Here, in such shift control, basically, the shift control only needs to feedback control only the tilt angle θ (speed ratio). However, the stroke x corresponds to the differentiation of the tilt angle θ and has a damping effect for suppressing vibration in the tilt control. Therefore, stroke feedback control is also performed so that the stroke x detected by the stroke sensor 38 matches the target stroke. If the contact position between the roller 35 and the input / output disks 30 and 40 is known, the relationship between the gear ratio and the tilt angle is determined only by the geometric shape, so the gear ratio is replaced with the tilt angle, and the tilt angle is changed. It can also be replaced by a ratio.
[0027]
In FIG. 3, the gear ratio is detected by the tilt angle of the tilt angle sensor 37, but it may be a gear ratio obtained from the input shaft speed and the output shaft speed. Further, instead of the stroke of the trunnion 36, a tilt angle change amount, an input rotation speed change amount, and a gear ratio change amount may be used.
[0028]
In the present embodiment, the feedback gain of the trunnion stroke and the tilt angle in the controller 80 is changed according to the operating conditions.
[0029]
FIG. 4 shows a configuration for feedback control in the controller 80. As described above, the target gear ratio is determined based on the accelerator opening and the vehicle speed, and the tilt angle command value corresponding to the target gear ratio is determined. The tilt angle command value is input to the subtractor 81. The subtractor 81 receives the actually measured tilt angle detection value, and the subtractor 81 calculates and outputs the deviation θ between the target and the current tilt angle.
[0030]
The deviation Δθ that is the output of the subtractor 81 is input to the tilt angle feedback gain setting unit 82. The tilt angle feedback gain setting unit 82 multiplies the tilt angle deviation Δθ by a predetermined feedback gain kθ to calculate kθ × Δθ, which is a feedback input value of the tilt angle feedback control. This kθ × Δθ is the hydraulic control amount corresponding to the target value of the trunnion stroke determined according to the difference between the target speed ratio and the current speed ratio.
[0031]
The output kθ × Δθ of the tilt angle feedback gain setting unit 82 is input to the subtractor 83. The subtracter 83 also receives a feedback input value kx × x that is a target value of a trunnion stroke obtained by multiplying the measured current trunnion stroke x by a predetermined feedback gain kx in the stroke feedback gain setting unit 84. This feedback gain input value kx × x is also a hydraulic control amount corresponding to the target value of the trunnion stroke.
[0032]
As a result, the difference between the control amount kθ × Δθ of the target trunnion stroke and the control amount kx × x based on the actual trunnion stroke x is calculated, and this difference is supplied to the flow control valve 85 as the control amount of the flow control valve 85. The That is, feedback control for the trunnion stroke is performed.
[0033]
Then, the hydraulic pressure controlled by the flow control valve 85 is supplied to the trunnion 36 of the toroidal CVT 100, and its stroke is controlled. Then, by this stroke control, the tilt angle is changed, and the gear ratio control is performed so as to match the target gear ratio. The constituent elements shown in FIG. 4 correspond to an identification model for setting the feedback gains kθ and kx.
[0034]
In this embodiment, the feedback gains kθ and kx are set according to the operation conditions at that time. This control system design method will be described with reference to FIG. First, a provisional control gain before optimal design that can stabilize the controlled object is set (S11). In this state, the gain is substantially constant at a predetermined frequency for each operating condition, that is, a target tilt angle command value that is a control input for a predetermined input / output disk pressing force, input rotational speed, and gear ratio. The model identification is performed using the signal such as the M-sequence signal as an input value and the trunnion stroke and tilt angle data as output values (S12). That is, a linear model (identification model) near the operating point is identified for each operating condition (input torque, tilt angle, rotation speed).
[0035]
A model including a flow control valve and a variator model to be controlled is calculated from the obtained identification model and the gain before the optimum design by back calculation (S13).
[0036]
Specify the target control performance (responsiveness, stability) for each operating condition (disk pressing force Fc, tilt angle (θ), rotation speed (Ni)) using the model that represents the control object that was found. The optimum feedback gains kθ and kx are obtained (S14).
[0037]
In FIG. 5, only the proportional gain is shown for simplicity, but each gain of PID control may be used. Further, an internal constant of a controller with two inputs and one output may be used as one controller.
[0038]
Further, the controller may be gain-scheduled by an LMI controller (a robust controller capable of gain-scheduling with parameters) using the above operating conditions as parameters. Further, the operating oil temperature may be added as an operating condition for gain setting.
[0039]
FIG. 6 shows a comparison based on the input rotational speed when the speed change is performed in an actual apparatus. The upper diagram shows the case where the input torque is 100 Nm and the output rotational speed is 1000 rpm, and the lower diagram shows the case where the input torque is 100 Nm and the output rotational speed is 2000 rpm. Although the gains kθ and kx have considerably different values depending on the input rotational speed, the responsiveness to the target tilt angle is almost the same, and the effectiveness of the control of this embodiment is understood.
[0040]
Next, a method for storing a gain map that becomes a problem when the feedback gain set for each driving condition is actually used in the form of an ECU (electronic control unit) of the vehicle will be described.
[0041]
As a method of calculating the feedback gain, a method of calculating the gain by interpolation using a map for each operating condition may be used. However, only the number of operating conditions, the number of feedback signals, and the type of gain (proportional, differential, and integral gains) are mapped. Since this is necessary, the capacity of the map increases. Therefore, the capacity can be reduced by calculating the feedback gain using a function having each operation condition as a parameter. This function is, for example, as shown in FIG. 7 when there are three types of operating conditions: disc pressing force Fc, input rotational speed Ni, and tilt angle θ. In the drawing, the tilt angle feedback gain kθ is shown on the left side, and the values of kθ with respect to Ni and θ in three types of disk pressing forces Fc1, Fc2, and Fc3 are shown. Further, in the figure, the right side shows the trunnion stroke feedback gain kx, and shows the values of kx with respect to Ni and θ in the three types of disk pressing forces Fc1, Fc2, and Fc3.
[0042]
Further, these feedback gains kθ and kx are expressed by the following equations.
[0043]
[Expression 1]
kθ = fθ (Fc, Ni, θ)
kx = fx (Fc, Ni, θ) (1)
In this equation (1), kθ is a tilt angle feedback gain, kx is a stroke feedback gain, Fc is a disk pressing force, Ni is an input rotation speed, and θ is a tilt angle.
[0044]
As an example, equation (1) can be expressed by the following linear multiple regression equation.
[0045]
[Expression 2]
kθ = α ₀ + α ₁ Fc + α ₂ Ni + α ₃ θ
kx = β ₀ + β ₁ Fc + β ₂ Ni + β ₃ θ (2)
Here, α ₀ , α ₁ , α ₂ , α ₃ , β ₀ , β ₁ , β ₂ , and β ₃ are coefficients.
[0046]
Thus, in the present embodiment, the tilt angle feedback gain kθ and the trunnion stroke feedback gain kx are changed according to the operating conditions (disk pressing force Fc, input rotational speed Ni, tilt angle θ). Thus, the tilt angle control can be performed more appropriately, and the shift control can be performed with a substantially constant response regardless of the driving conditions when shifting for speeding up and deceleration.
[0047]
In the above-described example, the two feedback gains kθ and kx are determined based on the three operating conditions, but the present invention is not necessarily limited to this. Further, only one of the feedback gains kθ and kx may be changed depending on the operating conditions. It is also preferable to add the operating oil temperature to the operating conditions.
[0048]
Further, as described above, any of the gear ratio and the tilt angle may be detected.
[0049]
【The invention's effect】
As described above, according to the present invention, the feedback gain of the roller tilt angle or the roller rotation axis offset is changed according to the operating conditions. As a result, gear ratio control can be performed with an appropriate feedback gain under the driving conditions at that time, and the shift response and stability can be kept constant.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a toroidal CVT.
FIG. 2 is a diagram illustrating tilting of a roller.
FIG. 3 is a diagram showing a configuration of trunnion stroke and tilt angle control.
FIG. 4 is a diagram showing a configuration of an identification model.
FIG. 5 is a diagram showing a design procedure.
FIG. 6 is a diagram showing a response at the time of shifting.
FIG. 7 is a diagram illustrating values of feedback gains kθ and kx.
[Explanation of symbols]
10 input shaft, 30 input disc, 40 output disc, 50 hydraulic piston chamber, 60 counter gear, 70 output shaft, 80 controller.

Claims (5)

A toroidal conductive member having an input / output disk and a roller for transmitting power between the input / output disk by frictional engagement in the middle;
An input / output disk pressing force control unit for controlling the pressing force of the input / output disk by hydraulic pressure;
A toroidal CVT having a shift control unit for changing the tilt angle of the roller and controlling the transmission ratio by offsetting the rotation axis of the roller from a position where the rotation axis of the roller and the rotation axis of the input / output disk are orthogonal to each other. In
A feedback control unit that feeds back the roller tilt angle and the roller rotation axis offset amount;
And roller tilt angle, the feedback gain for at least one of the roller rotation axis offset amount, and the input and output disks pressing force, and one of the roller tilt angle Contact and input speed, on the basis A toroidal CVT gear change control device characterized by being changed. The apparatus of claim 1.
And the roller tilt angle, the feedback gain for each of the roller rotation axis offsets, and input and output disks pressing force, and one of the roller tilt angle Contact and input speed, changing based on A toroidal CVT shift control device characterized by the above. The apparatus according to claim 1 or 2,
The roller tilt angle is detected by a roller tilt angle or a gear ratio, and a toroidal CVT shift control device. The device according to any one of claims 1 to 3,
The roller rotation shaft offset amount is detected by any one of a roller rotation shaft offset amount, a roller tilt angle change amount, a gear ratio change amount, and an input rotation speed change amount. . In the device according to any one of claims 1 to 4,
  The relationship between the roller tilt angle and the feedback gain for at least one of the roller rotation axis offset amounts, with respect to the input / output disk pressing force, and any one of the roller tilt angle and the input rotation speed, A toroidal CVT speed change control device characterized in that the feedback gain is determined using a stored relationship in advance.

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