Control device of friction fastening element and control method

Abstract

To suppress a degradation in an energy consumption when a friction fastening element is in a released state.SOLUTION: A friction fastening element 10 includes: a first friction panel 14 and a second friction panel 24 which comes into a fastened state and a released state; and a lubrication device 36 for supplying a lubrication fluid for lubricating between the first friction panel 14 and the second friction panel 24. When the lubrication fluid is supplied at a first flow rate in the released state, the lubrication fluid supply amount is set at a second flow rate which is larger than the first flow rate when a rotational speed difference between the first friction panel 14 and the second friction panel 24 is a first threshold value or more. In the released state, after the lubrication fluid supply amount is set at the second flow rate and when the rotational speed difference is less than a second threshold value which is smaller than the first threshold value, the lubrication fluid supply amount is set at a first flow rate.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The technology disclosed herein belongs to the technical field of a control device and a control method for a frictional engagement element. [Background technology]

[0002] Conventionally, a friction fastening element has been known that transmits power from a cylindrical outer member to an outer member by fastening together a plurality of outer friction plates engaged with the outer member and a plurality of inner friction plates engaged with an inner member disposed inside the outer member.

[0003] The hydraulic clutch actuation device disclosed in Patent Document 1 is equipped with a pressure regulating member that regulates the pressure of hydraulic oil to a commanded hydraulic pressure. The pressure regulating member separates the discharged oil into hydraulic oil and lubricating oil to be supplied to the friction engagement part, and is capable of changing the flow path area that determines the oil supply flow rate of the lubricating oil. The control device controls the pressure regulating member so that, when the friction engagement part is engaged, the flow path area becomes a set area that is variably set based on the rotational speed difference between the rotational speed of the first friction engagement element (first friction plate) and the rotational speed of the second friction engagement element (second friction plate), and controls the hydraulic pump so that, when the friction engagement part is engaged, the hydraulic oil is regulated to the commanded hydraulic pressure by the pressure regulating member whose flow path area is the set area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-149458 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the frictional engagement elements are in a disengaged state, if the first friction plate rotates at high speed and the difference between the rotational speeds of the first friction plate and the second friction plate increases, the second friction plate may vibrate. Vibration of the second friction plate increases drag resistance, adversely affecting energy consumption. When the control described in Patent Document 1 is applied when the frictional engagement elements are in a disengaged state, the amount of lubricant supplied increases as the difference in rotational speed increases. Therefore, when the first friction plate rotates at high speed, the lubricant is expected to reduce vibration of the second friction plate.

[0006] However, after careful consideration, the inventors of the present application found that the rotational speed difference at which the second friction plate begins to vibrate is different from the rotational speed difference at which the second friction plate starts to vibrate and then stops vibrating. With the control described in Patent Document 1, when the second friction plate is vibrating, there is a risk that the lubricating oil will be insufficient, and the vibration of the second friction plate will not be sufficiently suppressed. Furthermore, with the control described in Patent Document 1, when the second friction plate is not vibrating, there is a risk that the amount of lubricating oil supplied will be excessive, and drag resistance will increase due to the viscosity of the lubricating oil.

[0007] The technology disclosed herein has been made in view of the above points, and its purpose is to suppress the deterioration of energy consumption when the frictional engagement element is in a disengaged state. [Means for solving the problem]

[0008] In order to solve the above problem, a first aspect of the technology disclosed herein is directed to a control device for a frictional engagement element, and includes first and second friction plates that are in an engaged state and a released state, a first member that engages with the first friction plate and rotates together with the first friction plate, a second member that engages with the second friction plate and to which rotational power is transmitted from the first member in the engaged state, a lubricant oil supply unit that supplies lubricant oil to lubricate between the first friction plate and the second friction plate, and a control unit that controls the lubricant oil supply unit, wherein in the released state, when the supply amount of lubricant oil is a first flow rate and a rotational speed difference between the first friction plate and the second friction plate is equal to or greater than a first threshold, the control unit sets the supply amount of lubricant oil to a second flow rate that is greater than the first flow rate, and in the released state, after setting the supply amount of lubricant oil to the second flow rate, when the rotational speed difference becomes less than a second threshold that is smaller than the first threshold, sets the supply amount of lubricant oil to the first flow rate.

[0009] In the first aspect, after the rotational speed difference becomes equal to or greater than the first threshold and the lubricant supply rate is set to the second flow rate, the supply rate remains at the second flow rate until the rotational speed difference becomes less than the second threshold, even if the rotational speed difference becomes less than the first threshold. Therefore, even if the second friction plate starts to vibrate, the lubricant flow rate can be kept high until the rotational speed difference becomes less likely to vibrate. Therefore, even if the second friction plate starts to vibrate, the lubricant can suppress the vibration of the second friction plate.

[0010] Furthermore, when the supply rate of lubricating oil is the first flow rate, even if the rotation speed difference becomes equal to or greater than the second threshold, the supply rate remains at the first flow rate until the rotation speed difference becomes equal to or greater than the first threshold. This makes it possible to prevent an excessive amount of lubricating oil from increasing drag resistance.

[0011] Therefore, the control device can suppress the deterioration of energy consumption when the frictional engagement element is in the disengaged state.

[0012] In this specification, the term "flow rate" refers to the amount of supply per unit time.

[0013] A second aspect of the technology disclosed herein is the first aspect, wherein the control unit, in the released state, sets the supply amount of lubricating oil to the second flow rate, and then, when the rotation speed difference is equal to or greater than the second threshold value and the lubricating oil filling rate reaches a predetermined percentage, sets the supply amount of lubricating oil to a third flow rate that is greater than the first flow rate and less than the second flow rate.

[0014] In the second aspect, it is possible to prevent an increase in drag resistance due to an excessive amount of lubricant, thereby allowing the control device to prevent a deterioration in energy consumption when the frictional engagement element is in a disengaged state.

[0015] a first member that engages with the first friction plate and rotates together with the first friction plate; a second member that engages with the second friction plate and receives rotational power from the first member in the engaged state; a lubricant supply unit that supplies lubricant to lubricate the space between the first friction plate and the second friction plate; and a control unit that controls the lubricant supply unit. In the disengaged state, when the amount of lubricant supplied is a first flow rate and a rotational speed difference between the first friction plate and the second friction plate is equal to or greater than a first threshold, the control unit increases the amount of lubricant supplied to a second flow rate that is greater than the first flow rate; and in the disengaged state, after increasing the amount of lubricant supplied to the second flow rate, increases the amount of lubricant supplied to the first flow rate when the rotational speed difference becomes less than the first threshold and the filling rate of lubricant in the first friction plate and the second friction plate reaches a predetermined rate.

[0016] In the third aspect, by increasing the amount of lubricating oil supplied, vibration of the second friction plate can be suppressed, and an increase in drag resistance can be suppressed. Furthermore, by shortening the period during which the amount of lubricating oil supplied is increased, energy consumption by the lubricating oil supply unit can be reduced. Therefore, the control device can suppress a deterioration in energy consumption when the frictional engagement element is in a disengaged state.

[0017] A fourth aspect of the technology disclosed herein is the third aspect, wherein, in the released state, after the control unit sets the lubricant supply rate to the second flow rate, when the rotation speed difference becomes less than a second threshold value that is smaller than the first threshold value, the control unit sets the lubricant supply rate to the first flow rate even if the lubricant filling rate has not reached the specified rate.

[0018] In the fourth aspect, when the rotational speed difference becomes sufficiently small, the amount of lubricant supplied is reduced, thereby reducing energy consumption by the lubricant supply unit. Furthermore, until the rotational speed difference becomes sufficiently small, the lubricant filling rate is maintained at a level that is neither too low nor too high. This prevents an increase in drag resistance due to vibration of the second friction plate, and also prevents an increase in drag resistance due to excessive lubricant. Therefore, the control device can prevent a deterioration in energy consumption when the frictional engagement element is in a disengaged state.

[0019] A fifth aspect of the technology disclosed herein is any one of the first to fourth aspects, wherein the first threshold value is a value set in consideration of the viscosity of the lubricating oil in the frictional fastening element, the gap between the first friction plate and the second friction plate, and the static friction between the second friction plate and the second member.

[0020] In the fifth aspect, the rotation speed difference at which the second friction plate starts to vibrate is set with high precision, thereby enabling the control device to suppress deterioration of energy consumption when the frictional engagement element is in a disengaged state.

[0021] A sixth aspect of the technology disclosed herein is any one of the first, second, and fourth aspects, wherein the second threshold value is a value set in consideration of the viscosity of the lubricating oil in the frictional fastening element, the gap between the first friction plate and the second friction plate, and the dynamic friction between the second friction plate and the second member.

[0022] In the sixth aspect, the rotational speed difference at which the second friction plate is less likely to vibrate is set with high precision, thereby enabling the control device to suppress deterioration of energy consumption when the frictional engagement element is in a disengaged state.

[0023] A seventh aspect of the technology disclosed herein is any one of the first to fourth aspects, further comprising a rotation speed difference calculation unit that calculates the rotation speed difference, wherein the first friction plate, the second friction plate, the first member, the second member, and the lubricant oil supply unit constitute part of an automatic transmission, and the rotation speed difference calculation unit calculates the rotation speed difference based on the gear position of the automatic transmission and the input rotation speed or the output rotation speed of the automatic transmission.

[0024] In the seventh aspect, the configuration of the control device can be made as compact as possible.

[0025] An eighth aspect of the technology disclosed herein is directed to a method for controlling a frictional engagement element, the frictional engagement element including first and second friction plates that are in an engaged state and a disengaged state, a first member that engages with the first friction plate and rotates together with the first friction plate, a second member that engages with the second friction plate and to which rotational power is transmitted from the first member in the engaged state, and a lubricant oil supply unit that supplies lubricant oil to lubricate between the first friction plate and the second friction plate, the method comprising: a first step of supplying lubricant oil at a first flow rate in the disengaged state; a second step of increasing the amount of lubricant oil supplied to a second flow rate that is greater than the first flow rate when a rotational speed difference between the first friction plate and the second friction plate becomes equal to or greater than a first threshold value during the first step in the disengaged state; and a third step of increasing the amount of lubricant oil supplied to the first flow rate when the rotational speed difference becomes less than a second threshold value that is smaller than the first threshold value after the second step in the disengaged state.

[0026] A ninth aspect of the technology disclosed herein is directed to a method for controlling a frictional engagement element, in which the frictional engagement elements include first and second friction plates that are in an engaged state and a disengaged state, a first member that engages with the first friction plate and rotates together with the first friction plate, a second member that engages with the second friction plate and receives rotational power from the first member in the engaged state, and a lubricant supply unit that supplies lubricant to lubricate between the first and second friction plates, and the method includes: a first step of supplying lubricant at a first flow rate in the disengaged state; a second step of increasing the amount of lubricant supplied to a second flow rate that is greater than the first flow rate when a rotational speed difference between the first and second friction plates becomes equal to or greater than a first threshold value during the first step in the disengaged state; and a step of increasing the amount of lubricant supplied to the first flow rate when, after the second step in the disengaged state, the rotational speed difference becomes less than the first threshold value and the filling rate of lubricant in the first and second friction plates reaches a predetermined rate. [Effects of the Invention]

[0027] As described above, according to the technology disclosed herein, the control device can suppress the deterioration of energy consumption when the frictional engagement element is in the disengaged state. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of an automatic transmission having friction engagement elements controlled by a control device according to a first exemplary embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a frictional fastening element. [Figure 3] FIG. 3 is an exploded perspective view of the frictional fastening element. [Figure 4] FIG. 4 is a block diagram showing a control system for supplying lubricating oil to frictional engagement elements. [Figure 5] FIG. 5 is a graph showing the relationship between the rotation speed difference and the drag resistance. [Figure 6] FIG. 6 is a diagram illustrating the conditions under which the second friction plate vibrates. [Figure 7]FIG. 7 is a flowchart showing the processing operations in vibration suppression control. [Figure 8] FIG. 8 is a cross-sectional view showing the plate storage chamber when the filling rate reaches a predetermined rate. [Figure 9] FIG. 9 is a flowchart showing a process for calculating the amount of ATF filled in the plate accommodating chamber. [Figure 10] FIG. 10 is a time chart showing the relationship between the rotation speed difference, the lubricant filling rate, and the amount of lubricant supplied in vibration suppression control. [Figure 11] FIG. 11 is a flowchart showing the processing operation in vibration suppression control of the control device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, exemplary embodiment 1 will be described in detail with reference to the drawings. In the following description, the direction in which the cylindrical axis of a drum 22 (described later) extends will be referred to as the "axial direction," the direction of the radius or diameter centered on the cylindrical axis will be referred to as the "radial direction," and the direction rotating around the cylindrical axis will be referred to as the "circumferential direction."

[0030] First Embodiment (1) Overall structure of the automatic transmission FIG. 1 schematically shows an automatic transmission 1 having a frictional engagement element 10 according to the first embodiment. The automatic transmission 1 is a transmission mounted on an automobile. The automatic transmission 1 is interposed between a drive source E such as an engine or a motor and wheels W. The automatic transmission 1 accelerates or decelerates the rotational power output from the drive source E and outputs it to the wheels W.

[0031] The automatic transmission includes a housing 2, a rotating shaft 4, a transmission device 6, and a connecting / disconnecting device 8.

[0032] The housing 2 forms the outer shell of the automatic transmission 1. The housing 2 houses the connecting / disconnecting device 8 and the transmission device 6, and supports the rotary shaft 4 in a rotatable state.

[0033] The interrupter 8 is connected to the drive source E. The interrupter 8 is configured to input the rotational power output by the drive source E to the transmission 6 as needed. The interrupter 8 is, for example, a torque converter.

[0034] The transmission 6 is disposed around the rotating shaft 4. The transmission 6 switches the rotation speed of the rotational power input from the connecting / disconnecting device 8 and transmits it to the rotating shaft 4. The rotational power output from the rotating shaft 4 of the automatic transmission 1 is transmitted to the wheels W. The transmission 6 incorporates multiple planetary gear mechanisms to switch the output rotation speed, and clutch devices and / or brake devices (frictional engagement elements 10) to switch these planetary gear mechanisms. The automatic transmission 1 is configured to switch between forward and reverse directions and rotational speeds by changing the operating state of these clutch devices or brake devices.

[0035] FIG. 1 shows an enlarged view of a frictional engagement element 10 provided in the transmission 6. In this embodiment, the frictional engagement element 10 is used as a brake device for the transmission 6. In the transmission 6, the clutch device and the brake device are functionally different but structurally almost the same. The following explanation will be given of the case where the frictional engagement element 10 is used as a brake device.

[0036] (2) Frictional fastening element Fig. 2 is a cross-sectional view of the frictional fastening element 10. Fig. 3 is an exploded perspective view of the frictional fastening element 10.

[0037] 2 and 3, the frictional engagement element 10 includes a plurality of first friction plates 14, a plurality of second friction plates 24, a hub 12 that engages with the first friction plates 14 and rotates together with the first friction plates 14, and a drum 22 that engages with the second friction plates 24 and to which rotational power is transmitted from the hub 12. The frictional engagement element 10 also includes a piston 30 that is axially movably disposed on one axial side of the second friction plates 24, a cover member 32 that is attached to the end face of the drum 22 on the piston 30 side so as to cover the piston 30, and an end plate 34 that is disposed on the other axial side of the second friction plates 24. The first friction plates 14 and the second friction plates 24 may be collectively referred to simply as "friction plates."

[0038] (2-1) Hub, drum 2 and 3, the hub 12 is disposed inside the drum 22 and is rotatable relative to the drum 22. The hub 12 is a cylindrical member. The rotary shaft 4 passes through the inside of the hub 12. A plurality of axially extending internal spline teeth 16 are formed on the outer circumferential surface of the hub 12 at intervals in the circumferential direction.

[0039] The drum 22 is a bottomed cylindrical member having a cylindrical peripheral wall portion 22a and a disk-shaped bottom wall portion 22b, through the center of which the rotating shaft 4 passes. The drum 22 is disposed coaxially with the rotating shaft 4 inside the housing 2 and is fixed to the housing 2. The rotating shaft 4 passes through the drum 22 along its central axis. Furthermore, the drum 22 and the hub 12 are disposed concentrically. The drum 22 supports the hub 12 so that the hub 12 can rotate around its cylindrical axis. Furthermore, on the inner peripheral surface of the drum 22, external spline teeth 26 extending in the axial direction of the drum 22 are formed in a row spaced apart circumferentially.

[0040] As shown in FIG. 2, the outer peripheral surface of the hub 12 and the inner peripheral surface of the drum 22 face each other in the radial direction. An annular space is formed between the outer peripheral surface of the hub 12 and the inner peripheral surface of the drum 22, serving as a plate accommodating chamber 40. When the automatic transmission 1 is in operation, lubricating oil (ATF: Automatic Transmission Fluid) is circulated and supplied to the plate accommodating chamber 40 from a lubrication device 36, which includes an oil pump 36c (see FIG. 4) and a flow control valve 36d (see FIG. 4). The lubrication device 36 is provided in the automatic transmission 1. The lubrication device 36 introduces ATF into the plate accommodating chamber 40 through an oil introduction passage 36a formed inside the hub 12 and an oil supply hole 12a provided to communicate the oil introduction passage 36a with the outer periphery of the hub 12. The ATF that has flowed into the plate accommodating chamber 40 flows out from an oil drain hole 22c provided to communicate the plate accommodating chamber 40 with the outer periphery of the drum 22. The ATF flowing out of the drum 22 is returned to the lubrication device 36 through an oil return passage 36b formed inside the housing 2. In this way, the frictional engagement element 10 is a wet frictional engagement element in which the ATF is circulated and supplied. The lubrication device 36 corresponds to a lubricating oil supply unit.

[0041] (2-1) First friction plate, second friction plate 2 and 3, the first friction plates 14 are annular plate members made of metal. The first friction plates 14 are arranged on the outer periphery of the hub 12 and are aligned in the axial direction.

[0042] A plurality of internal spline grooves 15 are formed at intervals in the circumferential direction on the inner peripheral edge of each first friction plate 14. The internal spline grooves 15 of each first friction plate 14 engage with internal spline teeth 16 of the hub 12. In other words, each first friction plate 14 is spline-engaged with the outer periphery of the hub 12. As a result, each first friction plate 14 is disposed on the outer periphery of the hub 12 so as to be slidable in the axial direction, and is prevented from rotating relative to the hub 12.

[0043] As shown in Fig. 3, the second friction plates 24 are annular plate members made of metal and thicker than the first friction plates 14. The second friction plates 24 are arranged side by side in the axial direction inside the drum 22. Each second friction plate 24 is arranged between each first friction plate 14. Specifically, the first friction plates 14 and the second friction plates 24 are arranged alternately in the axial direction inside the drum 22.

[0044] Each second friction plate 24 has a plurality of external spline grooves 25 formed at intervals in the circumferential direction on its outer circumferential edge. The external spline grooves 25 of each second friction plate 24 engage with external spline teeth 26 formed on the inner circumferential portion of the drum 22. In other words, each second friction plate 24 is spline-engaged with the inner circumferential portion of the drum 22. As a result, each second friction plate 24 is disposed on the inner circumferential portion of the drum 22 so as to be slidable in the axial direction, and is prevented from rotating relative to the drum 22.

[0045] 2, a ring groove extending in the circumferential direction is formed in the inner peripheral portion of the drum 22 on the other axial side of the end plate 34. A resilient, arc-shaped snap ring 23 is fitted into the ring groove. Fitting the snap ring 23 into the ring groove prevents the end plate 34 from moving axially to the other side.

[0046] As shown in FIG. 2 , the piston 30 is disposed inside the drum 22 and is movable in the axial direction of the drum 22. By sliding the piston 30 in the axial direction, the second friction plates 24 and the first friction plates 14 are moved axially, thereby switching the frictional engagement element 10 between an engaged state and a released state. Specifically, when the piston 30 is moved from one side to the other in the axial direction in the released state, the first friction plates 14 and the second friction plates 24 come into close contact with each other in the axial direction, and the frictional engagement element 10 is switched to the engaged state. On the other hand, when the piston 30 is moved from one side to the other in the axial direction in the engaged state, the first friction plates 14 and the second friction plates 24 move away from each other in the axial direction, and the frictional engagement element 10 is switched to the released state. When the frictional engagement element 10 is in the engaged state, a braking force is applied to the hub 12, and rotation of the hub 12 is stopped. On the other hand, when the frictional engagement element 10 is in the released state, rotation of the hub 12 relative to the drum 22 is permitted.

[0047] (2-3) Piston The piston 30 is integrally formed of a pressing portion 30a, an operating portion 30b, and the like.

[0048] The pressing portion 30a is located in the plate accommodating chamber 40, and is arranged further axially to one side than the friction plates. The pressing portion 30a is arranged to face the second friction plate 24, which is located furthest axially to one side. On the other hand, the operating portion 30b is located inside the hub 12, and is arranged between the spring 31 provided on the input side and the hydraulic chamber 38 provided on one axial side. The hydraulic chamber 38 is partitioned liquid-tightly by the operating portion 30b.

[0049] The actuating part 30b is biased toward the output side by the elastic force of the spring 31. Pressurized oil is supplied to or discharged from a hydraulic pump (not shown) to the hydraulic chamber 38 as needed, causing hydraulic pressure to act on the actuating part 30b, causing the actuating part 30b to move in the axial direction.

[0050] When pressure oil is supplied to the hydraulic chamber 38, the operating part 30b slides to the other side in the axial direction against the elastic force of the spring 31. When pressure oil is discharged from the hydraulic chamber 38, the operating part 30b slides to one side in the axial direction due to the elastic force of the spring 31.

[0051] As the actuating portion 30b moves due to this hydraulic control, the pressing portion 30a moves axially within the plate accommodating chamber 40, advancing and retreating to one side and the other side in the axial direction. When pressure oil is supplied to the hydraulic chamber 38, the actuating portion 30b moves to the other side in the axial direction, and the pressing portion 30a moves toward the other side in the axial direction, bringing the first friction plates 14 and the second friction plates 24 into close contact with each other. This places the frictional engagement element 10 in an engaged state. On the other hand, when oil is discharged from the hydraulic chamber 38, the actuating portion 30b moves to one side in the axial direction, and the pressing portion 30a moves toward the other side in the axial direction, separating the first friction plates 14 and the second friction plates 24. This places the frictional engagement element 10 in a released state.

[0052] (3) Lubrication system control system As shown in FIG. 3, the control device for the frictional engagement element 10 includes an ECU (Electrical Control Unit) 100 for controlling the lubrication device 36. The ECU 100 is a controller based on a well-known microcomputer and includes a central processing unit (CPU), a memory, and an interface (I / F) circuit. The CPU executes programs. The memory is configured, for example, with a random access memory (RAM) or a read-only memory (ROM) and stores programs and data. The interface circuit inputs and outputs electrical signals. The functions of the ECU 100 are realized when the CPU reads and executes the programs stored in the memory. The ECU 100 is an example of a control unit.

[0053] As shown in Fig. 4, various sensors SW1 to SW5 are electrically connected to the ECU 100. The sensors SW1 to SW5 are electrically connected to the ECU 100 via, for example, a CAN (Controller Area Network). The sensors SW1 to SW5 output signals to the ECU 100. The sensors include the following sensors. Vehicle speed sensor SW1: Measures the vehicle speed from the number of rotations of the wheels W. Accelerator opening sensor SW2: Measures the accelerator opening corresponding to the amount of accelerator pedal operation. Input rotation speed sensor SW3: Measures the rotation speed of the input shaft of the automatic transmission 1. Output rotation speed sensor SW4: Measures the rotation speed of the rotary shaft 4 of the automatic transmission 1. Oil temperature sensor SW5: Measures the temperature of the oil including the ATF.

[0054] The ECU 100 determines the operating state of the automatic transmission 1 based on the signals from these sensors SW1 to SW5, and calculates the control amount of each device, including the lubrication device 36, according to a predetermined control logic. The control logic is stored in a memory. The control logic includes calculating the target amount and / or the control amount using a map stored in the memory.

[0055] The ECU 100 controls the gear position of the automatic transmission 1 based on the detection results of, for example, a vehicle speed sensor SW1, an accelerator opening sensor SW2, an input rotation speed sensor SW3, and an output rotation speed sensor SW4.

[0056] The ECU 100 calculates the difference between the rotation speed of the first friction plate 14 and the rotation speed of the second friction plate 24 in the frictional engagement element 10 (hereinafter simply referred to as the rotation speed difference) based on the gear position of the automatic transmission 1 and the detection results of the input rotation speed sensor SW3 or the output rotation speed sensor SW4. The ECU 100 sets the supply amount (flow rate) of ATF to lubricate the gap between the first friction plate 14 and the second friction plate 24 based on the rotation speed difference. The memory of the ECU 100 stores maps, supply patterns, calculation formulas, etc. for setting the ATF supply amount, and the CPU of the ECU 100 sets the ATF flow rate based on these. The ECU 100 constitutes a rotation speed difference calculation unit.

[0057] The ECU 100 outputs an electrical signal related to the calculated amount of ATF to be supplied to the lubrication device 36. The lubrication device 36 operates the oil pump 36c and the flow rate control valve 36d based on the electrical signal to adjust the amount of ATF to be supplied to the frictional engagement element 10.

[0058] (4) Drag resistance When the frictional engagement element 10 is in a disengaged state, drag resistance occurs in the first friction plate 14. The drag resistance varies depending on the difference in rotation speed between the first friction plate 14 and the second friction plate 24. In the disengaged state, no rotational power is input to the second friction plate 24, and the rotation speed of the second friction plate 24 decreases, so the rotation speed of the first friction plate 14 becomes higher than the rotation speed of the second friction plate 24.

[0059] Figure 5 is a graph showing the relationship between the difference in rotation speed and drag resistance. The solid line shows the drag resistance during the ascending process when the difference in rotation speed is increased from a small state, and the dashed line shows the drag resistance during the descending process when the difference in rotation speed is decreased from a large state.

[0060] As shown in Figure 5, during the increase in the rotational speed difference, drag resistance increases rapidly as the rotational speed difference increases, then peaks and decreases rapidly as the rotational speed difference increases. Drag resistance then gradually increases as the rotational speed difference increases, and increases rapidly as the rotational speed difference increases once the rotational speed difference exceeds a certain value. During the decrease in rotational speed after the sudden increase in the rotational speed difference, even if the rotational speed difference decreases, drag resistance does not decrease as much as during the increase in rotational speed, and remains greater than during the increase in rotational speed. Once the rotational speed difference becomes small to a certain extent, drag resistance during the decrease in rotational speed becomes approximately the same as drag resistance during the increase in rotational speed.

[0061] In the first embodiment, the frictional engagement element 10 is a brake device, and therefore the rotational speed difference corresponds to the rotational speed of the first friction plate 14. The reason that drag resistance increases when the rotational speed difference is small, i.e., when the rotational speed of the first friction plate 14 is low, is due to shear torque generated when the first friction plate 14 rotates while cutting off the ATF. As the rotational speed of the first friction plate 14 increases, centrifugal force causes the ATF to diffuse in the radial direction, reducing the shear torque and the drag resistance. Thereafter, as the rotational speed of the first friction plate 14 increases, drag resistance gradually increases due to the influence of the viscosity of the ATF. Then, when the rotational speed of the first friction plate 14 exceeds the aforementioned certain value, the second friction plate 24 vibrates (fluttering occurs), and drag resistance increases rapidly.

[0062] The conditions for the second friction plates 24 to vibrate are related to the fluid negative pressure from the ATF and the friction force between the second friction plates 24 and the drum 22. As shown in FIG. 6, fluid negative pressure is input to the second friction plates 24 from both axial sides, generating first negative pressure energy Ep1 and second negative pressure energy Ep2 based on the fluid negative pressure. A static friction force is generated between the second friction plates 24 and the drum 22, and the energy required to overcome this static friction force, i.e., the energy required to overcome the maximum static friction force between the second friction plates 24 and the drum 22, is defined as counter-friction energy Ef. For the second friction plates 24 to start vibrating, the absolute value of the difference between the first negative pressure energy Ep1 and the second negative pressure energy Ep2 must be greater than the counter-friction energy Ef. In other words, for the second friction plates 24 to start vibrating, the following equation 1 must be satisfied:

[0063] |Ep1-Ep2|>Ef (Equation 1) The first negative pressure energy Ep1 and the second negative pressure energy Ep2 are affected by the wedge pressure effect caused by the tilt of the second friction plate 24. Specifically, the first negative pressure energy Ep1 and the second negative pressure energy Ep2 become larger as the gap between the first friction plate 14 and the second friction plate 24 becomes smaller, as the viscosity of the ATF becomes higher, and as the rotation speed of the first friction plate 14 becomes higher. In other words, the rotation speed of the first friction plate 14 at which the above formula 1 is established is determined by the viscosity of the ATF, the gap between the first friction plate 14 and the second friction plate 24, and the static friction between the second friction plate 24 and the drum 22.

[0064] When the above formula 1 is established and the second friction plate 24 starts to vibrate, the friction force acting between the second friction plate 24 and the drum 22 becomes a kinetic friction force. If the counter-friction energy after the second friction plate 24 starts to vibrate is Ef', then in order for the second friction plate 24 to continue vibrating, the following formula 2 must be established.

[0065] |Ep1-Ep2|>Ef' (Equation 2) Because the kinetic friction force is smaller than the maximum static friction force, the counter-friction energy Ef' after the second friction plates 24 start to vibrate is smaller than the counter-friction energy Ef before the second friction plates 24 start to vibrate. The rotation speed of the first friction plates 14 at which the above formula 2 is satisfied is lower than the rotation speed of the first friction plates 14 at which the above formula 1 is satisfied. Therefore, once the above formula 1 is satisfied and the second friction plates 24 start to vibrate, even if the rotation speed of the first friction plates 14 decreases, the above formula 2 is satisfied and the second friction plates 24 continue to vibrate. When the rotation speed of the first friction plates 14 drops to a rotation speed at which the above formula 2 is no longer satisfied, the second friction plates 24 stop vibrating.

[0066] For the above reasons, the relationship between the rotational speed difference and the drag resistance forms a hysteresis curve as shown in Figure 5.

[0067] (5) Vibration suppression control If the vibration of the second friction plates 24 increases the drag resistance, the energy consumption of the automatic transmission 1 deteriorates. Conventionally, the vibration of the second friction plates 24 is suppressed by increasing the flow rate of ATF as the rotation speed difference increases. However, as described above, the drag resistance caused by the vibration of the second friction plates 24 exhibits hysteresis with respect to the rotation speed difference. Therefore, when the second friction plates 24 are vibrating, there is a risk that the amount of ATF supplied may be insufficient, and the vibration of the second friction plates 24 may not be sufficiently suppressed. Conversely, when the second friction plates 24 are not vibrating, there is a risk that the amount of ATF supplied may be excessive, and the drag resistance may increase due to the viscosity of the ATF.

[0068] Therefore, in the first embodiment, vibration suppression control is executed to suppress vibration of the second friction plate 24 by controlling the flow rate of the ATF, taking into consideration the hysteresis of the drag resistance as shown in FIG.

[0069] 7 is a flowchart of vibration suppression control executed by the ECU 100. The processing according to this flowchart is executed by the CPU reading a program from memory. This flowchart is executed after warm-up of the drive source E is complete. While the flowchart is being executed, the ECU 100 constantly reads information from the sensors SW1 to SW5 and calculates the difference in rotation speed between the first friction plate 14 and the second friction plate 24.

[0070] In step S101, the ECU 100 determines whether the current supply amount of ATF is a first flow rate. The first flow rate is the supply amount in a state where it is assumed that no vibration occurs in the second friction plate 24. If the current supply amount of ATF is the first flow rate (YES), the ECU 100 proceeds to step S102. If the current supply amount of ATF is not the first flow rate (NO), the ECU 100 proceeds to step S104.

[0071] In the next step S102, the ECU 100 determines whether the rotation speed difference Cd is equal to or greater than a first threshold value Cc1. The first threshold value Cc1 is the rotation speed at which the second friction plate 24 is deemed to start vibrating. The first threshold value Cc1 is set in consideration of the viscosity of the ATF in the friction engagement element 10, the distance between the first friction plate 14 and the second friction plate 24, and the static friction between the second friction plate 24 and the drum 22. The first threshold value Cc1 is not particularly limited, but is, for example, 12,000 rpm. If the result of the determination is YES, that is, the rotation speed difference Cd is equal to or greater than the first threshold value Cc1, the ECU 100 proceeds to step S103. If the result of the determination is NO, that is, the ECU 100 returns. The viscosity of the ATF in the friction engagement element 10 is the viscosity at the oil temperature when the drive source E has completed warming up.

[0072] In step S103, the ECU 100 switches the supply amount of ATF to a second flow rate. The second flow rate is a flow rate greater than the first flow rate. The second flow rate may be a constant flow rate as long as it is greater than the first flow rate, or may be a flow rate calculated based on the oil temperature and the rotation speed difference Cd.

[0073] In the next step S104, the ECU 100 determines whether the rotation speed difference Cd is less than a second threshold value Cc2. The second threshold value Cc2 is a value lower than the first threshold value Cc1. The second threshold value Cc2 is a value higher than the rotation speed difference at which the drag resistance peaks on the side where the rotation speed difference is small, as shown in FIG. 5. The second threshold value Cc2 is the rotation speed at which the vibration of the second friction plate 24 is deemed to have stopped after the second friction plate 24 starts vibrating. The second threshold value Cc2 is a value set in consideration of the viscosity of the ATF in the friction engagement element 10, the gap between the first friction plate 14 and the second friction plate 24, and the dynamic friction between the second friction plate 24 and the drum 22. The second threshold value Cc2 is not particularly limited, but is, for example, 6000 rpm. If the rotation speed difference Cd is less than the second threshold value Cc2 (YES), the ECU 100 proceeds to step S107. If the rotation speed difference Cd is equal to or greater than the second threshold value Cc2 (No), the ECU 100 proceeds to step S105. The viscosity of the ATF in the frictional engagement element 10 is the viscosity at the oil temperature when the warm-up of the drive source E is complete.

[0074] In step S105, the ECU 100 determines whether the ATF filling rate in the plate accommodating chamber 40 is equal to or greater than a predetermined rate. As shown in FIG. 8 , the predetermined rate is a rate at which the amount of ATF filled in the plate accommodating chamber 40 is such that approximately one-third of the second friction plate 24 in the radial direction from its lower end is immersed in the ATF. As shown in FIG. 9 , the ECU 100 calculates the amount of ATF discharged from the drum 22 based on the rotation speed of the first friction plate 14 and the ATF oil temperature. The ECU 100 calculates the current amount of ATF filled in the plate accommodating chamber 40 by subtracting the amount of ATF discharged from the drum 22 from the sum of the current ATF flow rate and the previously calculated amount of ATF filled in the plate accommodating chamber 40. The ECU 100 calculates the ATF filling rate in the plate accommodating chamber 40 based on the calculated amount of ATF filled and the volume of the plate accommodating chamber 40. If the result is YES, that is, the filling rate of the ATF in the plate accommodating chamber 40 is equal to or greater than the predetermined rate, the ECU 100 proceeds to step S106. If the result is NO, that is, the filling rate of the ATF in the plate accommodating chamber 40 is less than the predetermined rate, the ECU 100 returns to step S104.

[0075] In step S106, ECU 100 switches the amount of ATF supplied to a third flow rate. The third flow rate is greater than the first flow rate and less than the second flow rate, and is a flow rate that maintains the filling rate of ATF in plate housing chamber 40 at a predetermined rate. As long as the third flow rate is greater than the first flow rate and less than the second flow rate, it may be a constant flow rate or a flow rate calculated based on the oil temperature and the rotation speed difference Cd. After step S106, ECU 100 returns to step S104.

[0076] In step S107, the ECU 100 switches the amount of ATF supplied to the first flow rate. After step S107, the ECU 100 returns.

[0077] 10 is a time chart showing an example of the rotation speed difference, ATF filling rate, and ATF flow rate when the vibration suppression control described above is executed. In the initial state, the frictional engagement element 10 is in the engaged state, and the rotation speed difference is 0. In the time chart shown here, the first flow rate, the second flow rate, and the third flow rate are constant values.

[0078] At time t1, when the frictional engagement element 10 is released, the rotation speed difference gradually increases. At this time, the flow rate of the ATF is the first flow rate, and the filling rate of the ATF is lower than the predetermined rate.

[0079] At time t2, the rotation speed difference becomes equal to or greater than the first threshold value Cc1. The ATF flow rate is maintained at the first flow rate until time t2, and the ATF filling rate is also maintained lower than the predetermined rate until time t2. After time t2, the ATF flow rate is increased from the first flow rate to the second flow rate. The increase in the ATF flow rate causes the ATF filling rate to rise.

[0080] At time t3, when the ATF filling rate reaches a predetermined rate, the flow rate of the ATF is reduced from the second flow rate to the third flow rate. By reducing the ATF flow rate, the ATF filling rate does not increase but is maintained at the predetermined rate.

[0081] At time t4, when the rotation speed difference becomes less than the first threshold value Cc1, the ATF flow rate is not reduced and the third flow rate is maintained, and the ATF filling rate is also maintained at a predetermined rate.

[0082] At time t5, the rotation speed difference becomes less than the second threshold Cc2. The ATF flow rate is reduced from the third flow rate to the first flow rate. As the ATF flow rate is reduced, the ATF filling rate is gradually reduced from the predetermined rate.

[0083] At time t6, when the frictional engagement element 10 is brought into the engagement state, the rotation speed difference decreases to 0. The flow rate of the ATF is maintained at the first flow rate, and the ATF filling rate remains lower than the predetermined rate.

[0084] (6) Effects of the First Embodiment Therefore, in the first embodiment, when the frictional engagement element 10 is in the disengaged state, the ECU 100 sets the ATF supply rate to a second flow rate greater than the first flow rate when the rotational speed difference between the first friction plate 14 and the second friction plate 24 is equal to or greater than a first threshold. After setting the ATF supply rate to the second flow rate when the frictional engagement element 10 is in the disengaged state, the ECU 100 sets the ATF supply rate to the first flow rate when the rotational speed difference is less than a second threshold that is smaller than the first threshold. As a result, even if the rotational speed difference is equal to or greater than the first threshold and the second friction plate 24 begins to vibrate, the ATF flow rate can be kept high until the rotational speed difference reaches a level that makes the second friction plate 24 less likely to vibrate. Therefore, even if the second friction plate 24 begins to vibrate, the ATF can suppress the vibration of the second friction plate 24. Furthermore, when the ATF supply rate is the first flow rate, even if the rotational speed difference becomes equal to or greater than the second threshold, the supply rate remains at the first flow rate until the rotational speed difference becomes equal to or greater than the first threshold. This prevents an excessive amount of ATF from increasing drag resistance. Therefore, the first embodiment can prevent a deterioration in energy consumption when the frictional engagement element 10 is in the disengaged state.

[0085] In the first embodiment, the ECU 100 sets the ATF supply rate to the second flow rate in the disengaged state, and then sets the ATF supply rate to a third flow rate that is greater than the first flow rate but less than the second flow rate when the rotational speed difference is equal to or greater than the second threshold value and the ATF filling rate in the plate accommodating chamber 40 reaches a predetermined rate. This prevents an increase in drag resistance due to an excessive amount of ATF. The first embodiment can prevent a deterioration in energy consumption when the frictional engagement element 10 is in the disengaged state.

[0086] In particular, in the first embodiment, the third flow rate is a flow rate that maintains the filling rate of the ATF in the plate accommodating chamber 40 at a predetermined rate. This maintains an appropriate amount of ATF in the plate accommodating chamber 40, thereby preventing an increase in drag resistance due to excess ATF. The first embodiment can prevent a deterioration in energy consumption when the friction engagement element 10 is in a disengaged state.

[0087] In the first embodiment, the first threshold value is set in consideration of the viscosity of the ATF in the frictional engagement element 10, the gap between the first friction plate 14 and the second friction plate 24, and the static friction between the second friction plate 24 and the drum 22. This allows the rotation speed difference at which the second friction plate 24 begins to vibrate to be set with high precision. The first embodiment can suppress deterioration in energy consumption when the frictional engagement element 10 is in a disengaged state.

[0088] In the first embodiment, the second threshold value is set in consideration of the viscosity of the lubricating oil in the frictional engagement element 10, the gap between the first friction plate 14 and the second friction plate 24, and the dynamic friction between the second friction plate 24 and the drum 22. This allows the rotation speed difference at which the second friction plate 24 is less likely to vibrate to be set with high precision. The first embodiment can suppress deterioration in energy consumption when the frictional engagement element 10 is in a disengaged state.

[0089] In the first embodiment, the ECU 100 calculates the difference in rotation speed between the first friction plate 14 and the second friction plate 24 based on the gear position of the automatic transmission 1 and the input rotation speed or the output rotation speed of the automatic transmission 1. This eliminates the need to provide a sensor to detect the rotation speed of the first friction plate 14 and a sensor to detect the rotation speed of the second friction plate 24. The first embodiment allows the automatic transmission 1 to have a compact configuration.

[0090] Second Embodiment Hereinafter, the second embodiment will be described in detail with reference to the drawings. In the following description, parts common to the first embodiment will be given the same reference numerals and detailed description thereof will be omitted.

[0091] (7) Vibration suppression control In the second embodiment, the configuration of the frictional engagement element 10 is the same as in the first embodiment. However, in the second embodiment, the processing operation of the ECU 100 in vibration suppression control is different from that in the first embodiment.

[0092] 11 is a flowchart of vibration suppression control executed by the ECU 100. The processing according to this flowchart is executed by the CPU reading a program from memory. This flowchart is executed after warm-up of the drive source E is complete. While the flowchart is being executed, the ECU 100 constantly reads information from the sensors SW1 to SW5 and calculates the difference in rotation speed between the first friction plate 14 and the second friction plate 24.

[0093] In step S201, the ECU 100 determines whether the current supply amount of ATF is the first flow rate. If the result is YES, that is, the current supply amount of ATF is the first flow rate, the ECU 100 proceeds to step S202. If the result is NO, that is, the current supply amount of ATF is not the first flow rate, the ECU 100 proceeds to step S204.

[0094] In the next step S202, the ECU 100 determines whether the rotation speed difference Cd is equal to or greater than the first threshold value Cc1. If the rotation speed difference Cd is equal to or greater than the first threshold value Cc1 (YES), the ECU 100 proceeds to step S203. If the rotation speed difference Cd is less than the first threshold value Cc1 (NO), the ECU 100 returns.

[0095] In step S203, ECU 100 switches the supply amount of ATF to a second flow rate. The second flow rate is a flow rate greater than the first flow rate. The second flow rate may be a constant flow rate as long as it is greater than the first flow rate, or may be a flow rate calculated based on the oil temperature and the rotation speed difference Cd.

[0096] In the next step S204, the ECU 100 determines whether the rotation speed difference Cd is less than the first threshold value Cc1. If the rotation speed difference Cd is less than the first threshold value Cc1 (YES), the ECU 100 proceeds to step S205. If the rotation speed difference Cd is equal to or greater than the first threshold value Cc1 (NO), the ECU 100 continues the determination in step S204.

[0097] In step S205, the ECU 100 determines whether the filling rate of the ATF in the plate accommodating chamber 40 is equal to or greater than a predetermined rate. If the result is YES, that is, the filling rate of the ATF in the plate accommodating chamber 40 is equal to or greater than the predetermined rate, the ECU 100 proceeds to step S207. If the result is NO, that is, the filling rate of the ATF in the plate accommodating chamber 40 is less than the predetermined rate, the ECU 100 proceeds to step S206.

[0098] In step S206, the ECU 100 determines whether the rotation speed difference Cd is less than the second threshold value Cc2. If the rotation speed difference Cd is less than the second threshold value Cc2 (YES), the ECU 100 proceeds to step S207. If the rotation speed difference Cd is equal to or greater than the second threshold value Cc2 (NO), the ECU 100 returns to step S204.

[0099] In step S207, the ECU 100 switches the amount of ATF supplied to the first flow rate. After step S207, the ECU 100 returns.

[0100] (8) Effects of the second embodiment In the second embodiment, when the ATF supply rate is a first flow rate and the rotational speed difference between the first friction plate 14 and the second friction plate 24 is equal to or greater than a first threshold value in the disengaged state, the ECU 100 sets the ATF supply rate to a second flow rate greater than the first flow rate. After setting the ATF supply rate to the second flow rate in the disengaged state, when the rotational speed difference becomes less than the first threshold value and the ATF filling rate for the first friction plate 14 and the second friction plate 24 reaches a predetermined ratio, the ECU 100 sets the ATF supply rate to the first flow rate. In this way, increasing the ATF supply rate can suppress vibration of the second friction plate 24 and an increase in drag resistance. Furthermore, because the period during which the ATF supply rate is increased can be shortened, energy consumption by the lubrication device 36 can be reduced. Therefore, the second embodiment can suppress deterioration in energy consumption when the frictional engagement element 10 is in the disengaged state.

[0101] In the second embodiment, after the ECU 100 sets the ATF supply rate to the second flow rate in the disengaged state, when the rotational speed difference becomes less than a second threshold value that is smaller than the first threshold value, the ECU 100 sets the ATF supply rate to the first flow rate even if the ATF filling rate has not reached the predetermined rate. This reduces the ATF supply rate when the rotational speed difference becomes sufficiently small, thereby reducing energy consumption by the lubrication device 36. Furthermore, until the rotational speed difference becomes sufficiently small, the ATF filling rate is maintained at a rate that is neither too low nor too high. This suppresses an increase in drag resistance due to vibration of the second friction plate 24, and also suppresses an increase in drag resistance due to excessive ATF. Therefore, the ECU 100 can suppress deterioration in energy consumption when the frictional engagement element 10 is in the disengaged state.

[0102] Other Embodiments The technology disclosed herein is not limited to the above-described embodiments, and can be substituted within the scope of the claims.

[0103] For example, in the first and second embodiments, the first and second thresholds are set based on the viscosity of the ATF at the oil temperature when the driving source E is warmed up. However, the first and second thresholds may be set based on the current viscosity of the ATF. The current viscosity of the ATF can be calculated based on the detected value of the oil temperature sensor SW5 and a map or a calculation formula stored in the memory of the ECU 100. As the viscosity of the ATF increases, the energy due to the wedge pressure effect at the same engine speed increases. Therefore, the first and second thresholds may be set lower than in the first and second embodiments. Conversely, as the viscosity of the ATF decreases, the energy due to the wedge pressure effect at the same engine speed decreases. Therefore, the first and second thresholds may be set higher than in the first and second embodiments. Furthermore, the first and second thresholds may be changed before and after the driving source E is warmed up. Before the driving source E is warmed up, the oil temperature is low and the viscosity of the ATF is high. Therefore, the first and second thresholds may be set lower than in the first and second embodiments.

[0104] In the first and second embodiments described above, the ECU 100 calculates the difference in rotation speed between the first friction plate 14 and the second friction plate 24 based on the gear position of the automatic transmission 1 and the detection result of the input rotation speed sensor SW3 or the output rotation speed sensor SW4. However, the present invention is not limited to this, and a sensor for detecting the rotation speed of the first friction plate 14 and a sensor for detecting the rotation speed of the second friction plate 24 may be provided, and the ECU 100 may calculate the difference in rotation speed based on the detection results of these sensors.

[0105] Furthermore, in the first and second embodiments described above, the frictional engagement element 10 is a part of the automatic transmission 1, but it may also be applied to an in-vehicle device other than the automatic transmission 1.

[0106] In the first embodiment described above, when the filling rate of ATF in the plate accommodating chamber 40 becomes equal to or greater than a predetermined rate, the supply rate of ATF is switched from the second flow rate to the third flow rate. However, the supply rate of ATF may be kept at the second flow rate regardless of the filling rate of ATF in the plate accommodating chamber 40. In this case, the supply rate of ATF is maintained at the second flow rate until the rotation speed difference becomes less than the second threshold value.

[0107] The above-described embodiments are merely examples and should not be construed as limiting the scope of the present disclosure. The scope of the present disclosure is defined by the claims, and all modifications and variations that fall within the scope of the claims equivalents are within the scope of the present disclosure. [Industrial Applicability]

[0108] The technology disclosed herein is useful as a control device for a frictional engagement element. [Explanation of symbols]

[0109] 10 Frictional fastening elements 12 Hub (first member) 14 1st friction plate 22 Drum (second member) 24 2nd friction plate 36 Lubricating device (lubricating oil supply section) 100 ECU (control unit, rotation speed difference calculation unit)

Claims

1. A control device for a frictional engagement element, a first friction plate and a second friction plate that are in an engaged state and a disengaged state; a first member that engages with the first friction plate and rotates together with the first friction plate; a second member that engages with the second friction plate and to which rotational power is transmitted from the first member in the fastened state; a lubricant supply unit that supplies lubricant oil to lubricate the gap between the first friction plate and the second friction plate; a control unit that controls the lubricating oil supply unit, The control unit In the released state, when the supply amount of lubricating oil is a first flow rate and the difference in rotation speed between the first friction plate and the second friction plate becomes equal to or greater than a first threshold value, the supply amount of lubricating oil is set to a second flow rate that is greater than the first flow rate, a control device for a frictional engagement element that, after setting the supply amount of lubricating oil to the second flow rate in the released state, sets the supply amount of lubricating oil to the first flow rate when the rotational speed difference becomes less than a second threshold value that is smaller than the first threshold value.

2. 2. The frictional engagement element control device according to claim 1, The control unit sets the supply amount of lubricating oil to the second flow rate in the released state, and then, when the rotational speed difference is equal to or greater than the second threshold value and the lubricating oil filling rate reaches a predetermined percentage, sets the supply amount of lubricating oil to a third flow rate that is greater than the first flow rate and smaller than the second flow rate.

3. A control device for a frictional engagement element, a first friction plate and a second friction plate that are in an engaged state and a disengaged state; a first member that engages with the first friction plate and rotates together with the first friction plate; a second member that engages with the second friction plate and to which rotational power is transmitted from the first member in the fastened state; a lubricant supply unit that supplies lubricant oil to lubricate the gap between the first friction plate and the second friction plate; a control unit that controls the lubricating oil supply unit, The control unit In the released state, when the supply amount of lubricating oil is a first flow rate and the difference in rotation speed between the first friction plate and the second friction plate becomes equal to or greater than a first threshold value, the supply amount of lubricating oil is set to a second flow rate that is greater than the first flow rate, a control device for a frictional engagement element, which, after setting the supply amount of lubricating oil to the second flow rate in the released state, sets the supply amount of lubricating oil to the first flow rate when the rotational speed difference becomes less than the first threshold value and the filling rate of lubricating oil in the first friction plate and the second friction plate reaches a predetermined rate.

4. 4. The frictional engagement element control device according to claim 3, The control unit, in the disengaged state, sets the supply amount of lubricating oil to the second flow rate, and then, when the rotational speed difference becomes less than a second threshold value that is smaller than the first threshold value, sets the supply amount of lubricating oil to the first flow rate even if the lubricating oil filling rate has not reached the predetermined rate.

5. The control device for a frictional engagement element according to any one of claims 1 to 4, a control device for a frictional engagement element, wherein the first threshold value is a value set in consideration of the viscosity of the lubricating oil in the frictional engagement element, the gap between the first friction plate and the second friction plate, and the static friction between the second friction plate and the second member.

6. 5. The frictional engagement element control device according to claim 1, 2, or 4, a control device for a frictional engagement element, wherein the second threshold value is a value set in consideration of the viscosity of the lubricating oil in the frictional engagement element, the gap between the first friction plate and the second friction plate, and the dynamic friction between the second friction plate and the second member.

7. The control device for a frictional engagement element according to any one of claims 1 to 4, a rotation speed difference calculation unit that calculates the rotation speed difference, the first friction plate, the second friction plate, the first member, the second member, and the lubricant oil supply unit constitute a part of an automatic transmission, The rotation speed difference calculation unit calculates the rotation speed difference based on the gear position of the automatic transmission and the input rotation speed or the output rotation speed of the automatic transmission.

8. A method for controlling a frictional engagement element, comprising: The frictional fastening element is a first friction plate and a second friction plate that are in an engaged state and a disengaged state; a first member that engages with the first friction plate and rotates together with the first friction plate; a second member that engages with the second friction plate and to which rotational power is transmitted from the first member in the fastened state; a lubricant supply unit that supplies lubricant oil to lubricate between the first friction plate and the second friction plate, a first step of supplying lubricating oil at a first flow rate in the released state; a second step of setting the supply amount of lubricating oil to a second flow rate greater than the first flow rate when a rotational speed difference between the first friction plate and the second friction plate becomes equal to or greater than a first threshold value during the first step in the released state; and a third step of setting the supply amount of lubricating oil to the first flow rate when, in the released state, after the second step, the rotational speed difference becomes less than a second threshold value that is smaller than the first threshold value.

9. A method for controlling a frictional engagement element, comprising: The frictional fastening element is a first friction plate and a second friction plate that are in an engaged state and a disengaged state; a first member that engages with the first friction plate and rotates together with the first friction plate; a second member that engages with the second friction plate and to which rotational power is transmitted from the first member in the fastened state; a lubricant supply unit that supplies lubricant oil to lubricate between the first friction plate and the second friction plate, a first step of supplying lubricating oil at a first flow rate in the released state; a second step of setting the supply amount of lubricating oil to a second flow rate greater than the first flow rate when a rotational speed difference between the first friction plate and the second friction plate becomes equal to or greater than a first threshold value during the first step in the released state; and when, in the released state, after the second step, the rotational speed difference becomes less than the first threshold value and the filling rate of the lubricating oil in the first friction plate and the second friction plate reaches a predetermined rate, setting the supply amount of lubricating oil to the first flow rate.

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