JP3435624B2 - Lockup control device for automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock-up control device for an automatic transmission. As is well known, a lock-up clutch for directly connecting an engine and an automatic transmission, such as a vehicle equipped with a torque converter with a lock-up clutch or a fluid coupling with a lock-up clutch, is known. Vehicles equipped with this are known. In such a vehicle, the fuel cut region is expanded in order to absorb the torque pulsation in the low engine speed region or by increasing the engine speed as much as possible than the fuel cut speed. Therefore, a slip control means for performing slip control for maintaining the slip amount of the lock-up clutch at the target slip amount is provided. However, in the case of a lock-up clutch provided with a means for performing such slip control,
During the slip control, hunting of the slip amount, which is called a so-called judder, may occur to generate vibration. In order to solve such a problem, conventionally, for example, as described in Japanese Patent Application Laid-Open No. 7-042768, the rotational fluctuation of the drive wheels to which the power is transmitted via the lock-up clutch is used. A method of judging the above-mentioned judder vibration based on a difference from a rotation fluctuation of a driven wheel rotated only by contact with a road surface has already been proposed. [0006] However, there is provided a conventional control device comprising means for judging the judder vibration based on the difference between the rotation fluctuation of the driving wheel and the rotation fluctuation of the driven wheel. Has a disadvantage that it cannot be applied to a so-called full-time 4WD (always four-wheel drive) type vehicle in which driving force is transmitted to driving wheels in the front-rear direction without passing through a rotation fluctuation damping device. Was. In addition, in the full-time 4WD vehicle, there is a problem that the judder vibration is relatively easily generated because the running resistance is larger than that of a general 2WD (two-wheel drive) vehicle. The present invention has been made in view of the above situation, and has as its object to eliminate the need to interrupt slip control on the way, and to newly add a rotation sensor for judder detection. Without judder vibration, it can determine and control the judder vibration, and includes a full-time 4WD (constant four-wheel drive) system in which the driving force is transmitted to the front and rear driving wheels without passing through the rotation fluctuation damping device. An object of the present invention is to provide a lock-up control device for an automatic transmission having a judder judging means applicable to almost all types of driving systems. According to the present invention, there is provided a friction clutch having a direct connection mechanism interposed in a power transmission path for transmitting an output of an internal combustion engine. A lock-up control device for an automatic transmission capable of controlling a slip amount of a friction clutch by the direct coupling mechanism, a right side of a drive wheel from which power is transmitted from the friction clutch to the left and right via a differential gear device. Right drive wheel rotation fluctuation detecting means for detecting rotation fluctuations of the left and right driving wheels, and left and right driving wheel rotation fluctuation detecting means for detecting rotation fluctuation on the left side of the driving wheels. Judder judging means for judging the occurrence of judder vibration in the friction clutch based on a difference in rotation fluctuation;
And a slip control changing means for changing the control of the slip amount of the friction clutch when judging of the friction clutch is judged by the judging judgment means. The present invention will be described below in detail based on an embodiment of the present invention shown in the accompanying drawings. FIG. 1 is a skeleton diagram showing a schematic configuration of an automatic transmission for a vehicle, the speed of which is controlled by a hydraulic control device to which an embodiment of the present invention is applied. The vehicle shown in FIG. 1 is a so-called full-time 4WD.
(Always four-wheel drive) The power output from the engine 50 is input to the automatic transmission 15 via the torque converter 30 and then distributed by the central differential gear device 40. One of the distributed powers is transmitted from the rear propeller shaft 46 to the left and right rear wheels 20L and 20R via the rear operating gear unit 42, and the other power is
The power is transmitted from the gear power transmission mechanisms 43a and 43b to the left and right front wheels 21L and 21R via the front propeller shaft 45 and the front operating gear device 41. In the figure, reference numeral 47 denotes a front wheel right axle, and reference numeral 48 denotes a front wheel left axle. As shown in FIG. 2, the torque converter 30 includes a pump impeller 33 connected to the crankshaft 1 of the engine 50 and a pump impeller 33 fixed to the input shaft 2 of the automatic transmission 15. A turbine wheel 32 that is rotated by receiving oil from the engine, a stator wheel 36 fixed to a housing 35 that is a non-rotating member via a one-way clutch 34, and is connected to the input shaft 2 via a damper 37. And a lock-up clutch 31 provided. When the hydraulic pressure in the release-side oil chamber 39 is higher than that in the engagement-side oil chamber 38 in the torque converter 30 by the engagement control hydraulic control circuit 60 shown in FIG. Since the clutch 31 is in the disengaged state, torque is transmitted at a radiation increasing rate according to the input / output rotation speed ratio of the torque converter 30. However, when the oil pressure in the engagement-side oil chamber 38 is higher than that in the release-side oil chamber 39, the lock-up clutch 31 is engaged. The shaft 1 and the input shaft 2 are directly connected. Note that, in the figure, reference numeral 3 indicates an output shaft. The engagement control hydraulic control circuit 60 is constituted by, for example, an automatic transmission control valve unit (not shown), and shifts based on oil discharged from an oil pump (not shown) driven by the engine. , And is configured to supply pilot pressure to a lock-up control valve 80 shown in FIG. A lock-up solenoid 90 shown in FIG. 3 is provided with an automatic transmission control unit (hereinafter referred to as AT).
A valve that generates a lock-up control pressure PL / U in response to a duty command (repeatedly an ON signal and an OFF signal at a predetermined cycle) from a CU 70. That is, of the ON-OFF signal, the lockup control pressure PL / U increases as the ON time ratio increases, and the lockup control pressure PL decreases as the ON time ratio decreases.
/ U decreases. Specifically, at the time of lock-up release, as shown in FIG. 5, the ON time ratio of the duty signal from the ATCU 70 to the lock-up solenoid 90 is reduced, and the drain of the lock-up solenoid 90 is set to the "closed" state. To As a result, pilot pressure is applied to the oil chamber 81 of the lock-up control valve 80, and the valve 85 moves to the left. FIG. 3 shows this state. Then, the line pressure is divided into two by the relief valve, one is applied to the engagement side oil chamber 38 of the torque converter 31, and the other passes through the oil passage 82 to the oil passage 86 because the valve 85 is on the left side, It joins the release-side oil chamber 39 of the torque converter 31. Accordingly, the pressure in the engagement side oil chamber 38 and the pressure in the release side oil chamber 39 become equal, so that the lock-up is released. Conversely, at the time of lock-up engagement, the ATCU 7
From 0, the ON time ratio of the duty signal to the lock-up solenoid 90 is increased, the drain of the lock-up solenoid 90 is in the "open" state, and the pilot pressure applied to the oil chamber 81 is not applied. Accordingly, a pilot pressure is applied to the oil chamber 83 as a force for pushing the valve 85 of the lock-up control valve 80 rightward, the valve 85 moves rightward, and the oil passage 82 and the oil passage 86 are closed. Therefore, the line pressure is applied to the engagement-side oil chamber 38 but not to the release-side oil chamber 39, and the lock-up piston 31 is moved to the engagement side. Further, at the time of slip lock-up, as shown in FIG. 5, the ratio of the ON time of the duty signal from the ATCU 70 to the lock-up solenoid 90 is set to a value within a predetermined range, so that the drain of the lock-up solenoid 90 becomes It is halfway between "open" and "closed". In this case, since the valve 85 moves to a position where the pressures of the oil chamber 81 and the oil chamber 83 of the lock-up control valve 80 are balanced, the slip lock-up control pressure is adjusted. The automatic transmission 15 is, for example, as shown in FIG. 2, known as a so-called A / T composed of two planetary gear sets, such as a first planetary gear set 4 and a second planetary gear set 5. Stepped automatic transmission, the components of which are connected to each other or to a non-rotating member by a plurality of hydraulic friction engagement devices, so that a reverse gear stage and a plurality of forward gear stages are provided. It is configured to be able to switch to either. The central differential gear unit 40 distributes the power output from the output shaft 3 of the automatic transmission 15 to the rear wheel side and the front wheel side.
Numeral 2 is for transmitting the power distributed to the rear wheel side by the central differential gear device 40 evenly to the left and right rear wheels 20R, 20L. Thus, the power distributed to the front wheels is transmitted evenly to the left and right front wheels 21L and 21R. Further, the gear power transmission mechanism 43 is the same as that shown in FIG.
As shown in FIG. 5, the transmission includes a gear 43a connected to the output shaft 3 of the automatic transmission 15, and a gear 43b connected to the front propeller shaft 45. In the vehicle shown in FIG. 1, an engine rotation sensor 100 for detecting an engine rotation Ne and a turbine rotation sensor 101 for detecting a turbine rotation (transmission input rotation) Nt for shifting control of the automatic transmission. And an output shaft rotation sensor 102 for detecting an output shaft rotation (transmission output rotation) No, a throttle opening sensor 103 with an idle switch for detecting a throttle opening TVO, and an automatic transmission oil temperature (AT oil temperature) Tat. Each signal from the oil temperature sensor 104 to be detected is configured to be input to the ATCU 70. When applicable, the vehicle speed Vsen information from the vehicle speed sensor and the ON / OFF information of the idle switch (IdleSW) can be input from a switch signal. As described above, in the vehicle according to the present embodiment, the wheel speed sensors 105 provided on the respective wheels 21L and 21R.
L, 105R, the rotation speed of each wheel V21L, V
21R is configured to be detected. The wheel speed sensors 105L and 105R are originally used in an antilock braking system called ABS, but are not directly related to the gist of the present invention. Omitted. In the ATCU 70, as shown in FIG. 1, an internal arithmetic processing circuit CPU 71 processes each of the input signals according to a program stored in a ROM 73 in advance while utilizing a temporary storage function of a RAM 72, and performs automatic gear shifting. A control signal is output to a plurality of electromagnetic valves (not shown) in the hydraulic control circuit 60 to execute a shift control of the engine 15 and a slip control of the lock-up clutch 31. In the engagement control of the lock-up clutch 31, the lock-up clutch 31 is controlled based on the output shaft rotation speed (vehicle speed) No of the vehicle and the throttle valve opening TVO.
Is determined based on the relationship shown in FIG. 4. In the present embodiment, a connection is provided on the release region side and the low throttle valve opening side with respect to the boundary between the engagement region and the release region in order to improve fuel economy as much as possible without impairing drivability. A slip control region is provided for absorbing the torque fluctuation of the engine 50 while maintaining the effect. When it is determined that the running state of the vehicle is within the "engagement region" shown in FIG. 4, the ATCU 70, as described above, sets the engagement control hydraulic control circuit 60
Is issued to the lock-up solenoid 90 so that the duty ratio becomes the maximum value, and the lock-up clutch 31 is engaged. If it is determined that the running state of the vehicle is within the "release area" shown in FIG. 4, the ATCU 70 locks up the engagement control hydraulic control circuit 60 so that the duty ratio becomes the minimum value. A command is issued to the solenoid 90, and the lock-up clutch 31 is released. When it is determined that the running state of the vehicle is within the "slip control area" shown in FIG.
U70 is transmitted to the engagement control hydraulic control circuit 60 by, for example,
The duty ratio Dslip based on Equation 1 is commanded to the lock-up solenoid 90, and the lock-up control valve 80 moves to the neutral position, whereby the slip lock-up control pressure PL / U is supplied to the engagement side oil chamber, and the slip lock-up is performed. The control pressure PL / U is adjusted. Dslip = Dfwd + Df / b (Equation 1) That is, the target slip rotation speed NslipT
And the actual slip rotation speed Nslip (= Ne-Nt)
The feedforward control value Dfwd and the feedback control value Df / b are determined so that the deviation (= NsLip−NsLipT) from the above is eliminated, and the duty ratio Dslip for the lock-up solenoid 90 is calculated by adding them. Output. FIG. 6 is a functional block diagram for explaining a main part of the operation of the ATCU 70. In the figure, the rotation fluctuation of the right front wheel 21R is detected by the right driving wheel rotation fluctuation detecting means 200,
The left driving wheel rotation fluctuation detecting means 201 detects the left front wheel 21
The rotation fluctuation of L is detected. On the other hand, judder judging means 20
If the occurrence of judder vibration of the lock-up clutch 31 corresponding to the friction clutch is determined based on the difference between the rotation fluctuation of the right front wheel 21R and the rotation fluctuation of the left front wheel 21L during the slip control, the slip is determined. The slip control of the lock-up clutch 31 is changed by the control changing means 203. As shown in FIG. 7, there is almost no difference between left and right wheel rotation fluctuations when vibration due to judder occurs. On the other hand, the left and right wheel rotation fluctuations due to unevenness of the road surface due to a bad road or the like have a difference in the vibration period or vibration amplitude as shown in FIG. This is because the rotation fluctuation due to judder vibration of the lock-up clutch 31 corresponding to the friction clutch is transmitted equally to the left and right front wheels 21L and 21R via the central differential gear device 40 and the front operating gear device 41. This is because rotation fluctuations due to road surface irregularities due to bad roads and the like are input to the left and right front wheels 21L and 21R, respectively. Therefore, judder of the lock-up clutch 31 is determined based on the difference between the left and right wheel rotation fluctuations. Next, the ATCU 7 configured as described above is used.
The lock-up control operation of the lock-up clutch 31 by 0 will be described with reference to the flowchart shown in FIG. In FIG. 9, in step ST1, FIG.
Based on the relationship shown in (1), it is determined whether or not the running state of the vehicle is in the slip region. If the determination in step ST1 is denied, the control of the engagement area or the release area other than the main control (not shown) is performed and the main control ends, but if the judgment is affirmative, the process moves to step ST2. In step ST2, the rotation speed V21R of the right front wheel 21R detected by the wheel speed sensor 105R during the slip control by the right driving wheel rotation fluctuation detecting means 200.
(Vibration) cycle is within a predetermined cycle range and fluctuation (vibration)
It is determined whether or not the amplitude value is equal to or greater than a predetermined amplitude value. The predetermined cycle range and the predetermined amplitude value are set in advance so as to be detected as peculiar rotation fluctuations caused by judder vibration of the lock-up clutch 31, as in step ST4 described later. If the determination in step ST2 is affirmative, a predetermined number, for example, "1" is added to the contents of the counter C21R in step ST3, and step ST4 is executed. However, as soon as the determination in step ST2 is denied, step ST4 is executed. In step ST4, the wheel speed sensor 1 is performing slip control by the left front wheel rotation fluctuation detecting means 201.
It is determined whether or not the fluctuation (vibration) cycle of the rotation speed V21L of the right front wheel 21L detected at 05L is within a predetermined cycle range and the amplitude value of the fluctuation (vibration) is greater than or equal to a predetermined amplitude value. If the determination in step ST4 is affirmative, a predetermined number, for example, "1" is added to the content of the counter C21L in step ST5, and step ST6 is executed. Next, in step ST6, it is determined whether or not the sum of the counters C21R and C21L is equal to or greater than a predetermined value. That is, it is determined whether or not vibration that satisfies a condition set in advance so as to detect a specific rotation fluctuation due to judder vibration is caused by judder or road surface unevenness. Is determined. If step ST6 is denied, this routine ends after judder is not detected in step ST9 and a good road determination is stored. However, if this step ST6 is affirmed, then step ST7 is executed. At step ST7, the counter C21
It is determined whether the difference between R and C21L is within a predetermined range. As described above, if the vibration is caused by judder vibration, there is almost no difference between the counters C21R and C21L, and the determination in step ST7 is affirmative. However, if the vibration is caused by unevenness of the road surface, the determination in step ST7 is denied. . If step ST7 is affirmative, judder determination is stored in the following step ST8, and this routine ends. On the other hand, if step ST7 is denied, in step ST10 vibration is generated but not due to judder, so that the determination of a bad road is stored, and this routine ends. The lock-up control device for an automatic transmission according to this embodiment is, as described above, an internal combustion engine 50.
Is operated in a predetermined operation range, and when the slip amount of the friction clutch is controlled to be close to the target slip amount by the lock-up control device, the right driving wheel rotation fluctuation detecting means 200 detects the rotation fluctuation of the right driving wheel. The left driving wheel rotation fluctuation detecting means 201 detects the rotation fluctuation of the left driving wheel, and the judder judging means 202 detects the frictional fluctuation based on the left and right driving wheel rotation fluctuation difference during the slip control of the friction clutch. The occurrence of judder vibration of the clutch is determined. When judging of the friction clutch is determined, the slip control of the friction clutch is changed by the slip control changing means 203. Accordingly, the slip control is not interrupted, a new rotation sensor is not added for judder detection, and the rotational fluctuation of the drive wheels in the front-rear direction is not used for judder determination. Full-time 4WD in which the driving force is transmitted to the driving wheels without passing through the rotation fluctuation damping device
Judgment determination can be performed for vehicles of almost all drive systems including the (always four-wheel drive) system. Further, when judging is performed, slip control of the friction clutch is automatically changed so as to avoid judder, so that there is no fear that the drivability is deteriorated. The illustrated embodiment is merely an example of the present invention, and it goes without saying that the present invention can be modified in various ways without departing from the scope of the invention. Preferably, in a vehicle provided with a manual transmission instead of the automatic transmission of the vehicle, judder determination and slip control of the friction clutch are performed by a friction clutch between the manual transmission and the engine. May also be performed. More preferably, the friction clutch may not be a friction clutch provided in a torque converter with a lock-up clutch or a fluid coupling with a lock-up clutch. As described above, the lock-up control device for an automatic transmission according to the present invention operates the internal combustion engine in a predetermined operation range and controls the friction type clutch by the lock-up control device. When the slip amount is controlled near the target slip amount, the right drive wheel rotation fluctuation detecting means detects the right drive wheel rotation fluctuation, and the left drive wheel rotation fluctuation detection means detects the left drive wheel rotation fluctuation. On the other hand, when the judder judging means judges the occurrence of judder vibration of the friction clutch based on the difference between the right and left drive wheel rotation fluctuations during the slip control of the friction clutch, and judges the judder of the friction clutch. Then, the slip control of the friction clutch is changed by the slip control changing means. Therefore, in the lock-up control device for an automatic transmission according to the present invention, the slip control is not interrupted, a new rotation sensor is not added for judder detection, and the judder determination is performed. Since the rotational fluctuation of the driving wheel in the front-rear direction is not used, the driving force is transmitted to the driving wheel in the front-rear direction without passing through the rotation fluctuation damping device.
Judgment determination can be performed on vehicles of almost all drive systems including the WD (always four-wheel drive) system. Further, when judging is performed, the slip control of the friction clutch is automatically changed so as to avoid judder, so that there is an excellent effect that there is no fear that the drivability is deteriorated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a skeleton diagram showing one embodiment of a vehicle driving force transmission device and a control device to which the present invention is applied. FIG. 2 is an explanatory diagram illustrating a main configuration of a lockup control device for an automatic transmission according to an embodiment of the present invention. FIG. 3 is an explanatory diagram showing a configuration of a main part of the hydraulic control circuit of FIG. 1; FIG. 4 is a graph showing a relationship between a traveling state of a vehicle and an engagement state of a lock-up clutch used for engagement control of a lock-up clutch in FIG. FIG. 5 is a view showing output characteristics of the lock-up solenoid valve of FIG. 2; FIG. 6 is a functional block diagram of FIG. 1; FIG. 7 is a diagram showing rotation speed fluctuations of left and right driving wheels caused by judder vibration. FIG. 8 is a diagram showing left and right wheel rotational speed fluctuations of drive wheels caused by running on a rough road. FIG. 9 is a flowchart illustrating a control operation of the lock-up control device. DESCRIPTION OF SYMBOLS 31 Lock-up clutch 50 Internal combustion engine 60 Hydraulic control circuit for engagement control 70 Automatic transmission control unit (ATCU) 80 Lock-up control valve 90 Lock-up solenoid 200 Right driving wheel rotation fluctuation detecting means 201 Left driving wheel Rotation fluctuation detecting means 202 judder judging means 203 slip control changing means

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16H 59/00-63/48 F16D 25/00-39/00

Claims (1)

(1) A friction clutch provided with a direct coupling mechanism interposed in a power transmission path for transmitting an output of an internal combustion engine, and the friction of the friction clutch is reduced by the direct coupling mechanism. Automatic transmission lock-up control device that can control the amount,
Right drive wheel rotation fluctuation detecting means for detecting right-hand rotation fluctuation of the drive wheel from which power is transmitted to the left and right via the differential gear device from the friction clutch, and left-hand side for detecting left-hand rotation fluctuation of the drive wheel. Drive wheel rotation fluctuation detecting means; judder judging means for judging occurrence of judder vibration in the friction clutch based on a difference between the left and right driving wheel rotation fluctuations during the slip amount control of the friction clutch; A lock-up control device for an automatic transmission, comprising: slip control changing means for changing the control of the slip amount of the friction clutch when judging of the friction clutch is determined by the means.