JP2003314681A - Slip control device for clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out intended slip control for a lockup clutch even when engine torque is changed between positive and negative. <P>SOLUTION: By controlling the engaging force of a clutch comprising an input member to which torque is inputted from a power source, and an output member engaged with the input member with relatively sliding and to which torque is transferred from the input member, the slip control device for a clutch sets a difference in the number of rotations due to relatively sliding at a specified value. The slip control device for the clutch comprises a rotation deviation detecting means (a step S3) obtaining a deviation between the number of rotations of the input member and the number of rotations of the output member at a specified phase in periodically changes in the number of rotations of the input member with the changes in torque, in an operation state wherein the torque inputted from the power source to the input member is relatively changed between positive and negative; and an engaging force controlling means (a step S4) controlling the engaging force to make the deviation of the number of rotations agree with a predetermined target value. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling a clutch arranged in a drive system from a power source to a drive wheel in a vehicle to a slip state. 2. Description of the Related Art It is well known that various clutches are used to appropriately change the power transmission state in a drive system from a power source such as an engine to a drive wheel. As an example of the clutch, a lock-up clutch arranged in parallel with a fluid transmission mechanism such as a torque converter is known. [0003] Fluid transmission devices such as torque converters are:
In order to transmit power via a fluid, it is essential that the input side member and the output side member rotate relative to each other, and as a result, the power transmission efficiency may not be sufficiently high. The lock-up clutch is a clutch provided to solve such inconvenience.The input member and the output member are mechanically directly connected to each other on the input side and the output side of the torque converter. The power is transmitted without causing relative rotation of the power, thereby improving the power transmission efficiency. The lock-up clutch is, as described above,
Although it complements the torque converter in terms of power transmission efficiency, it also transmits torque fluctuations on the input side as it is, so torque fluctuations occur at low vehicle speeds when the power source speed is low. Vibration caused by the vehicle may be transmitted to the vehicle body, which may further increase noise, thereby deteriorating the ride comfort of the vehicle. So, conventionally,
In a predetermined running state, the lock-up clutch is controlled to a slip state, and torque is transmitted while interrupting or absorbing torque fluctuation on the input side, thereby improving fuel efficiency of the vehicle. In the slip control, a target value of a slip speed (or a slip rate), which is a deviation between an input speed and an output speed, is determined, and the detected slip speed matches the target value. The engagement pressure (or engagement force) of the lock-up clutch is feedback-controlled.
Therefore, in order to perform the slip control, it is necessary to detect a deviation between the input rotation speed and the output rotation speed.For example, in a state where the input rotation speed greatly changes due to a change in the input torque, When the input rotational speed decreases, the rotational speed difference disappears, and a situation occurs in which slip control cannot be performed as expected. More specifically, when the vehicle is running at a predetermined vehicle speed, the rotational speed on the output side of the clutch is relatively stable because the inertial force of the vehicle is large. On the other hand, when the rotation speed of the engine that is the power source decreases, the torque fluctuation appears relatively large. As a result, when the input rotation speed decreases due to the torque fluctuation, the input rotation speed decreases. The number may almost coincide with the output speed. In such a case, the input member and the output member are substantially in the same state as a so-called complete engagement (complete lockup) in which the input member and the output member are integrated, so that the torque fluctuation on the input side is directly transmitted to the output side. As a result, inconveniences such as deterioration of ride comfort occur. Therefore, in the invention described in Japanese Patent Application Laid-Open No. 5-141527, the input rotation speed of the lock-up clutch is detected, the minimum value of the input rotation speed is calculated, and the minimum value is detected as the output rotation speed. The engagement force of the lock-up clutch is controlled so as to be a predetermined target value higher than the predetermined value. That is, the control device described in this publication, by making the fastening force relatively small and making it easy to slip, even if the input rotation speed fluctuates greatly, the minimum rotation speed is always higher than the output rotation speed detection value. It is a device that controls to be higher. [0008] The conventional apparatus described in the above-mentioned publication is an apparatus for controlling the input rotation speed so as not to fall below the output rotation speed detection value even if the input rotation speed fluctuates greatly. This is a device for performing control in a so-called driving state in which the lock-up clutch and members on the output side are rotated by the output of a power source such as an engine connected to the input side of the lock-up clutch. In other words, the device performs the slip control on the premise of such a driving state. However, when the vehicle is running, a torque based on the running inertia of the vehicle is generated on the output side of the lock-up clutch. When the torque fluctuates, a so-called driven state may occur in which the input side torque is relatively smaller than the output side torque. In such a case, the input-side member of the lock-up clutch is driven by the torque input from the output side. The number will be less than the output speed. Since the above-described conventional device does not assume such a driven state, after all, the slip control in a state where the input rotation speed changes largely according to the fluctuation of the input side torque is performed as expected. It was difficult to do. The present invention has been made in view of the above technical problem. Even when the torque on the input side of the clutch fluctuates positively or negatively relative to the torque on the output side, the clutch of the clutch can be used. It is an object of the present invention to provide a control device capable of executing the slip control stably. According to the present invention, in order to achieve the above object, the input rotational speed periodically fluctuates with the periodic fluctuation of the input torque of the clutch. As a result, the slip control is performed by utilizing the fact that the input rotation speed becomes larger than the output rotation speed in the predetermined phase, or conversely, the input rotation speed becomes smaller and a difference in the rotation speed occurs. It is. More specifically, according to the first aspect of the present invention, the input member to which the torque is input from the power source is engaged with the input member with relative sliding, and the torque is transmitted from the input member. A clutch slip control device that sets the rotational speed difference due to relative slip to a predetermined value by controlling the engagement force of a clutch having an output member that is input to the input member from the power source. In an operating state in which the torque fluctuates positively and negatively relative to the torque output from the output member, the input member at a predetermined phase in the periodic fluctuation of the rotation speed of the input member accompanying the fluctuation of the torque. A rotational deviation detecting unit for determining a deviation between a rotational speed and a rotational speed of the output member; and an engaging force control unit for controlling the engaging force such that the deviation of the rotational speed matches a predetermined target value. It is slip control system according to claim. Therefore, according to the first aspect of the present invention, in an operating state in which the input torque changes relatively positively or negatively with respect to the torque output from the output member, the rotational speed at a predetermined phase of the periodically changing input rotational speed is determined. Is detected. The predetermined phase is preferably a phase at which the input rotation speed takes an extreme value or a phase close thereto. Since the detected input rotational speed deviates from the averaged rotational speed, a deviation from the output rotational speed occurs, and the deviation is detected by the rotational deviation detecting means. The rotational deviation detected in this manner is a positive or negative value other than zero, and the engagement force is controlled such that the rotational deviation matches the target value. That is, in the present invention, even if the input torque fluctuates relatively positively or negatively and the difference between the input rotational speed and the output rotational speed becomes transiently zero or positive and negative values accordingly, In order to control the engagement force, the value of the input rotation speed at a predetermined phase is adopted, so that the data for the slip control can be reliably obtained.
As a result, the expected slip control is reliably performed. Next, the present invention will be described based on specific examples. The clutch according to the present invention is a clutch for transmitting power of a power source such as an engine to an output side, and a clutch capable of transmitting torque with slippage. Therefore, a friction clutch is generally used. As an example, a lock-up clutch 2 incorporated in the torque converter 1 is shown in FIG. The torque converter 1 has a general configuration mounted on a vehicle, and is provided with a pump impeller 4 integrated with a front cover 3 as an input-side member and a turbine as an output-side member opposed thereto. A runner 5 is provided, and this turbine runner 5 is connected to an output shaft 6. A stator 7 for controlling the flow direction of fluid is disposed between the pump impeller 4 and the turbine runner 5 at a portion on the rotation center side, and the stator 7 is connected to a predetermined direction via a one-way clutch 8. It is connected to the fixing part 9. A lock-up clutch 2 is disposed facing the inner surface of the front cover 3 which is an input-side member. The lock-up clutch 2 is a disk-shaped member, and is attached to the turbine 5 or the output shaft 6 so as to be able to move back and forth in the axial direction. Then, the lock-up clutch 2 is pressed against the inner surface of the front cover 3 by the pressure difference between the hydraulic pressure on the front cover 3 side and the hydraulic pressure on the opposite side against the lock-up clutch 2 so as to be engaged or semi-engaged. And is configured to be separated from the inner surface of the front cover 3 to be in a released state. That is, the hydraulic pressure between the lock-up clutch 2 and the front cover 3
The lock-up clutch 2 is pressed against the inner surface of the front cover 3 and the pressing force (engagement force) thereof is in accordance with the pressure difference. The torque capacity of the lock-up clutch 2 increases as the engagement force increases, and when the torque capacity is larger than the torque to be transmitted, so-called complete lock-up (complete engagement)
State. When the engagement force is reduced from that state, and the torque capacity is accordingly lower than the torque to be transmitted, the lock-up clutch 2 slips. The slip ratio, that is, the rotational speed difference between the input-side member and the output-side member increases as the engagement force decreases. And
The state where the lock-up clutch 2 has no torque capacity is the completely released state. Each of the engagement, disengagement, and slip states of the lock-up clutch 2 is set by controlling the hydraulic pressure, and a control device 10 for that purpose is provided. The lock-up clutch control device 10 performs a calculation based on input data such as the engine speed Ne and the intake air amount Q, and outputs a hydraulic command signal based on the calculation result to lock the lock-up clutch 2. The state is controlled to any of engagement, release, and slip, and the slip rotation speed is controlled. The torque converter 1 including the lock-up clutch 2 is arranged as a mechanism constituting a part of a drive system from an engine 11 as a power source to drive wheels (not shown). That is, the above front cover 3
Is connected to the output shaft of the engine 11. Further, the output shaft 6 is connected to the transmission 12 and serves as an input shaft of the transmission 12. The engine 11 is a power source whose output torque may fluctuate greatly in a predetermined operating state. Source. The transmission 12 is a mechanism that changes the gear ratio stepwise or continuously and changes the input torque according to the gear ratio and outputs the torque. As an example, the transmission 12 changes according to the running state of the vehicle. This is an automatic transmission in which the gear ratio can be changed. As described above, when the lock-up clutch 2 is engaged, the front cover 3 as the input side member and the output shaft 6 as the output side member are directly mechanically connected to each other. Although the efficiency is improved, the torque fluctuation on the input side becomes the torque fluctuation on the output side as it is, and vibration and noise may be deteriorated. Therefore, when the engine speed is low and the vehicle speed is low, the lock-up clutch 2 is controlled to the slip state, and the lock-up clutch 2 is controlled so as to transmit the torque while interrupting or absorbing the torque fluctuation on the input side. In such a so-called slip control, a target rotational deviation is set according to the traveling state or driving state of the vehicle, and the engagement of the lock-up clutch 2 is adjusted so that the detected rotational deviation coincides with the target rotational deviation. This is performed by controlling the resultant force. Note that the rotational deviation is a difference between the input-side rotational speed (the engine rotational speed in the illustrated example) of the lock-up clutch 2 and the output-side rotational speed (the turbine rotational speed in the illustrated example). When the slip control is performed, if the vehicle speed is a relatively high vehicle speed and each of the rotational speeds is stable, the average rotational speed of the engine at predetermined time intervals is used as the input rotational speed. The actual rotational deviation is obtained by using the average rotational speed for each predetermined time as the output rotational speed, and the engagement force of the lock-up clutch 2, that is, the hydraulic pressure is controlled so that the actual rotational deviation matches the target rotational deviation. On the other hand, in a state where the engine torque fluctuates, a so-called driven state in which the engine torque is relatively small with respect to the output torque based on the traveling inertia force of the vehicle may occur. In a state where the fluctuation occurs, there is a case where a difference between the average rotational speeds hardly occurs.
Therefore, in the control device of the present invention, in an operating state in which the engine torque fluctuates greatly, the slip control of the lock-up clutch 2 is executed by obtaining the rotational deviation as described below. FIG. 1 is a flowchart for explaining an example of the control. First, it is determined whether or not the engine is in an operating range where the engine torque (engine torque) is reversed to positive or negative (step S1). Here, the positive or negative engine torque is positive when the torque is larger than the torque based on the inertial force of the vehicle acting on the output side of the torque converter 1 or the lock-up clutch 2, and negative when the torque is smaller. Therefore, the operating state in which the engine torque fluctuates in this way depends on the vehicle speed, the engine load, and the like. Therefore, the determination in step S1 is made by preparing an operating region in which the engine torque fluctuates positively or negatively by mapping the operating region such as the engine speed Ne and the intake air amount Q of the engine 11 into parameters. The determination can be made by determining whether or not the operating state indicated by the number Ne or the intake air amount Q is in the region. If a positive determination is made in step S1,
In the operating state at that time, the rotation speed on the input side of the torque converter 1 periodically fluctuates as shown in FIG. 2 due to the fluctuation of the engine torque. Further, although the inertia force of the vehicle acts on the output side of the torque converter 1, the torque on the output side fluctuates periodically, though the fluctuation width is small, because it is affected by the torque fluctuation on the input side. . Therefore, since the fluctuations of these rotation speeds are periodic, the average values of the rotation speeds are substantially equal and the difference is small, but the deviation of the peak value is large due to the difference in the amplitude. If the result of the determination in step S1 is affirmative, the peak value of the rotation speed on the input side and the peak value of the rotation speed on the output side are obtained, and the deviation between these peak values is calculated as the actual rotation deviation. (Step S2). In addition,
Since these peak values appear for each predetermined phase, the input-side rotation speed and the output-side rotation speed at that phase are set as the peak values. Therefore, if the number of rotations at a predetermined phase is determined, a number of rotations slightly deviating from a theoretical peak value may be determined. Further, the peak value may be a positive peak value or a negative peak value (so-called bottom value). Further, a slip rotational speed to be set by the lock-up clutch 2, that is, a target rotational deviation is set (step S3). This is the value of the map prepared in advance,
Alternatively, a value obtained by interpolating the map value with the input-side average rotation speed and the engine torque (engine torque) is employed. Then, the pressing force (engagement force) of the lock-up clutch 2 is feedback-controlled so that the actual rotation deviation coincides with the target rotation deviation (step S).
4). As described above, the actual rotational deviation is determined by the peak value of the input-side rotational speed and the peak value of the output-side rotational speed in a state where at least the input-side rotational speed fluctuates with the fluctuation of the engine torque. Therefore, the value is somewhat large. In other words, it indicates the slip rotation speed (slip rate) occurring in the lock-up clutch 2. Therefore, in step S4, control is performed to make the slip speed equal to the target value. If a negative determination is made in step S1, that is, if the engine torque is not in the operating range in which the engine torque is determined to be positive or negative, the control of the lock-up clutch 2 is performed in another range (step S1). Step S5). That is, appropriate control including slip control of the lock-up clutch 2 according to the actual operation state in which the engine torque is relatively stable is executed. Therefore, according to the control device for performing the above-described control according to the present invention, even when the input rotational speed changes greatly based on the periodic fluctuation of the input torque to positive or negative, the input rotational speed and Each rotation speed at a predetermined phase (at a predetermined time) at which a difference from the output rotation speed occurs is obtained, and slip control of the lock-up clutch 2 is executed using a rotation deviation based on the rotation speed. Therefore, the actual rotational deviation can be accurately grasped, and the slip rotational speed of the lock-up clutch 2 can be set to a desired rotational speed. In the above specific example, the difference between the peak value of the input rotation speed and the peak value of the output rotation speed is determined. However, the present invention is not limited to the above specific example. As the number, an average value, an averaged value, a value filtered by a low-pass filter, a band-pass filter, or the like may be used. This is because a torque based on the inertial force of the vehicle acts on the output side and the change is small. Further, in the above specific example, the lock-up clutch is described as an example of the clutch. However, the present invention can be applied to a control device that performs slip control for a clutch other than the lock-up clutch. As described above, according to the first aspect of the present invention, the input torque fluctuates positively or negatively with respect to the torque output from the output member, and accordingly, the input rotation speed and Even if the difference from the output rotational speed becomes zero transiently or becomes a positive or negative value, the value of the input rotational speed at a predetermined phase is adopted for controlling the engaging force. Thus, data for slip control can be reliably obtained, and as a result, slip control as intended can be reliably performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart for explaining an example of control executed by a control device according to the present invention. FIG. 2 is a diagram schematically illustrating periodic fluctuations of an input rotation speed and an output rotation speed that occur when the input torque is reversed to positive or negative. FIG. 3 is a diagram schematically showing an example of a drive system including a torque in which a lock-up clutch is built. [Description of Signs] 1. Torque converter, 2. Lock-up clutch,
3 ... Front cover, 4 ... Pump impeller, 5
... turbine runner, 10 ... lock-up clutch control device, 11 ... engine, 12 ... transmission.

Claims (1)

Claims: 1. An input member to which torque is input from a power source, and an output to which the input member is engaged with relative slip with slippage and torque is transmitted from the input member. A clutch slip control device that sets the rotational speed difference due to the relative slip to a predetermined value by controlling the engagement force of a clutch having a member and a clutch. The rotational speed of the input member at a predetermined phase in the periodic fluctuation of the rotational speed of the input member accompanying the fluctuation of the torque in an operating state that fluctuates relatively positively or negatively with respect to the torque output from the output member. A rotational deviation detecting means for calculating a deviation between the rotational speed of the output member and a rotational speed of the output member; and an engaging force controlling means for controlling the engaging force so that the deviation of the rotational speed coincides with a predetermined target value. A slip control device for a clutch, characterized in that: