JP4178761B2 - Control method of clutch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a clutch control method, and more particularly to a method for controlling a wet friction clutch disposed in a power transmission system of a vehicle.
[0002]
[Prior art]
The present inventors have provided a fluid coupling (including a torque converter) and a wet friction clutch in series in the middle of the power transmission path from the engine to the transmission, and the power of the vehicle that automatically connects and disconnects the wet friction clutch at the time of shifting. A new transmission device was developed. In this case, if a gear-in operation is performed while the vehicle is stopped, the clutch is automatically connected thereafter, and creep occurs. This is the same as a normal AT car.
[0003]
If the clutch is connected too early, a clutch engagement shock (so-called garage shock or the like) will occur. If it is too late, it will take time from the gear-in operation to the occurrence of creep, and the driver will not know when to depress the accelerator (large time lag). Therefore, in order to achieve both the clutch connection shock and the shortening of the connection time, the play area until the clutch starts to be engaged is suddenly contacted, and when the clutch starts to be connected, the connection speed is switched and the control is performed slowly. ing.
[0004]
More specifically, when the working fluid pressure for driving the clutch to connect / disconnect is changed according to the duty pulse output from the electronic control unit, and the clutch is connected from the disengaged state, the clutch is first connected. The electronic control unit outputs a predetermined start duty that makes a large contact near the position (this is called one-shot contact), and then electronically controls a predetermined slow contact duty that causes the clutch to be loosely connected after every predetermined time. Output from the unit.
[0005]
The clutch connection start position, in other words, the torque transmission start point at which the predetermined torque can be transmitted first is called the torque point, and this torque point is learned by the control unit and used as the connection speed switching point. The point occupies an important role in clutch control. The reason why the torque point is used as the learning value is that there are variations or individual differences in the clutch due to manufacturing errors or the like, and the torque point is different for each clutch.
[0006]
[Problems to be solved by the invention]
By the way, the individual differences of the clutches are absorbed by using the torque point learning value as a reference, but the vehicle conditions such as the working fluid temperature and the battery voltage vary during actual clutch control. Therefore, there is a problem that the clutch connection feeling, and thus the shift feeling, is not stable.
[0007]
That is, in the valve system that is duty-controlled by the electronic control unit, the output pressure (clutch control pressure) varies depending on the working fluid temperature and the applied voltage. Further, since the transmission torque of the fluid coupling varies depending on the engine speed when the clutch is controlled to be engaged, the clutch output torque with respect to a certain clutch engagement position also varies due to the variation of the clutch input torque.
[0008]
Accordingly, the present invention has been invented in view of the above problems, and an object thereof is to prevent instability of the clutch connection feeling and thus the shift feeling caused by variations in the vehicle situation.
[0009]
[Means for Solving the Problems]
The present invention changes the working fluid pressure for connecting / disconnecting the wet friction clutch disposed in the power transmission system of the vehicle according to the duty of the duty pulse output from the electronic control unit, A clutch position at which transmission of power from the engine to the transmission is started is a torque point, a duty corresponding to the torque point is a torque point learning value, and the torque point learning value is stored in the electronic control unit. When connecting the clutch from the disengaged state, first The torque point learning value stored in the electronic control unit is set near and on the disconnect side. In the clutch control method, a predetermined start duty is selected from a map and output from the electronic control unit, and thereafter, a predetermined slow engagement duty that causes the clutch to be loosely connected is output from the electronic control unit every predetermined time. , When a predetermined condition is met, In order to absorb individual differences and variations in clutch, the above Torque point learning value corresponding to the torque point when a predetermined condition is met And asked for Torque point learning value The Satisfy the above predetermined conditions Corrected based on a predetermined correction parameter related to the vehicle situation at the time With the corrected torque point learning value, In the above electronic control unit Update the stored torque point learning value On the other hand, when connecting the clutch from the disengaged state, the starting duty selected from the map is Torque point learning value of the updated electronic control unit And correction based on a predetermined correction parameter related to the vehicle situation during clutch control.
[0010]
Where above Predetermined conditions are met It is preferable that the correction parameter at the time and the correction parameter at the time of clutch control are the temperature of the working fluid, the battery voltage, or the engine speed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
[0012]
FIG. 1 shows a power transmission device for a vehicle in this embodiment. As illustrated, a transmission T / M is connected to the engine E via the clutch mechanism 1. The clutch mechanism 1 includes a fluid coupling (fluid coupling) 2 and a wet multi-plate clutch 3. The fluid coupling 2 is provided on the upstream side of the power transmission path from the engine E to the transmission T / M, and the wet multi-plate clutch 3 is provided in series on the downstream side. The fluid coupling here is a broad concept including a torque converter, and the torque converter is also used in the present embodiment.
[0013]
The fluid coupling 2 is interposed between the pump 4 connected to the output shaft (crankshaft) of the engine, the turbine 5 facing the pump 4 and connected to the input side of the clutch 3, and the turbine 5 and the pump 4. And a lock-up clutch 7 that engages and disconnects the pump 4 and the turbine 5. The wet multi-plate clutch 3 has its input side connected to the turbine 5 via the input shaft 3a, its output side connected to the input shaft 8 of the transmission T / M, and between the fluid coupling 2 and the transmission T / M. Connect and disconnect.
[0014]
The transmission T / M has an input shaft 8, an output shaft 9 arranged coaxially with the input shaft 8, and a countershaft 10 arranged parallel to these. An input main gear 11 is provided on the input shaft 8. The output shaft 9 is supported by a first speed main gear M1, a second speed main gear M2, a third speed main gear M3, a fourth speed main gear M4, and a reverse main gear MR. A main gear M6 is fixed. The countershaft 10 includes an input subgear 12 that meshes with the input main gear 11, a first speed subgear C1 that meshes with the first speed main gear M1, a second speed subgear C2 that meshes with the second speed main gear M2, and 3 A third speed sub gear C3 meshing with the speed main gear M3, a fourth speed sub gear C4 meshing with the fourth speed main gear M4, and a reverse sub gear CR meshing with the reverse main gear MR via the idle gear IR are fixed. In addition, a sixth-speed sub gear C6 that meshes with the sixth-speed main gear M6 is pivotally supported.
[0015]
According to this transmission T / M, when the sleeve S / R1 spline-engaged with the hub H / R1 fixed to the output shaft 9 is spline-engaged with the dog DR of the reverse main gear MR, the output shaft 9 rotates reversely. When the sleeve S / R1 is spline-engaged with the dog D1 of the first-speed main gear M1, the output shaft 9 rotates at the first speed. When the sleeve S / 23 that is spline-engaged with the hub H / 23 fixed to the output shaft 9 is spline-engaged with the dog D2 of the second-speed main gear M2, the output shaft 9 rotates at the second speed, and the sleeve When S / 23 is spline-engaged with the dog D3 of the third speed main gear M3, the output shaft 9 rotates at the third speed.
[0016]
When the sleeve S / 45 spline-engaged with the hub H / 45 fixed to the output shaft 9 is spline-engaged with the dog D4 of the 4-speed main gear M4, the output shaft 9 rotates at a speed equivalent to 4th speed, and the sleeve When S / 45 is spline-engaged with the dog D5 of the input main gear 11, the output shaft 9 rotates at the fifth speed (direct connection). When the sleeve S6 that is spline-engaged with the hub H6 fixed to the countershaft 10 is spline-engaged with the dog D6 of the sixth-speed sub-gear C6, the output shaft 9 rotates at the sixth speed. Each of the sleeves is manually operated by a shift lever in the cab through a shift fork and a shift rod (not shown).
[0017]
The wet multi-plate clutch 3 has a normal configuration. That is, although not shown in the drawings, in the clutch casing filled with oil, the clutch plates are alternately meshed with each other on the input side and the output side, and the clutch plates are pressed against each other by the clutch piston or released. Then, the clutch is connected and disconnected. Referring to FIG. 2, the clutch piston 27 is always biased to the disengagement side by the clutch spring 28, and the clutch 3 is engaged when a hydraulic pressure exceeding this is applied to the clutch piston 27. The clutch fastening force or the torque capacity of the clutch is increased according to the applied hydraulic pressure.
[0018]
Next, a hydraulic pressure supply device for supplying hydraulic pressure to the wet multi-plate clutch 3 will be described. As shown in FIG. 2, the oil in the oil tank 13 is sucked and discharged by the hydraulic pump OP through the filter 14, and the discharge pressure is adjusted by the relief valve 15 to create a constant line pressure PL. The oil of the line pressure PL is controlled (pressure-reduced) and sent to the clutch 3. For this reason, two valves, a clutch control valve CCV and a clutch solenoid valve CSV, are used. That is, a pilot operated hydraulic control system is employed in which the clutch control valve CCV connected to the main hydraulic line is opened and closed according to the pilot hydraulic pressure Pp sent from the clutch solenoid valve CSV. The magnitude of the pilot oil pressure Pp is changed according to a duty pulse output from an electronic control unit (hereinafter referred to as ECU) 16.
[0019]
That is, the clutch solenoid valve CSV is an electromagnetic valve having an electromagnetic solenoid, can be opened and closed steplessly, and is always supplied with the line pressure PL. Then, the duty pulse output from the ECU 16 is received, and the valve body is opened by an amount corresponding to the duty (duty ratio) D. As a result, the clutch solenoid valve CSV outputs the pilot hydraulic pressure Pp corresponding to the duty D.
[0020]
The clutch control valve CCV is a spool valve that is opened and closed steplessly based on the pilot oil pressure Pp, and is not electronically controlled. That is, the built-in spool is stroked to the open side according to the magnitude of the pilot oil pressure Pp, thereby adjusting the line pressure PL as appropriate and feeding it to the clutch 3 as the clutch pressure Pc. Thus, as a result, the hydraulic pressure supplied to the clutch 3 is duty-controlled by the ECU 16.
[0021]
An accumulator 17 is provided in the middle of the path connecting the clutch solenoid valve CSV and the clutch control valve CCV.
[0022]
FIG. 3 shows a characteristic diagram of the hydraulic pressure supply device. The horizontal axis represents the duty D of the duty pulse output from the ECU 16, more specifically, the on duty indicating the ratio of the solenoid on time in a predetermined control cycle (20 msec in the present embodiment). In this embodiment, the clutch is completely engaged when the duty D is 0 (%). This is to make it possible to maintain the running of the vehicle by setting the clutch in the connected state even when no power is supplied to the clutch solenoid valve CSV (so-called off-stack state) due to an electric system failure or the like. .
[0023]
As shown in the figure, the larger the duty D is, the smaller the contact is, and the smaller the duty is. As the value of the duty D decreases, the value of the pilot hydraulic pressure Pp output from the clutch control valve CCV increases proportionally, and accordingly, the hydraulic pressure supplied to the clutch, that is, the clutch pressure Pc, and the torque capacity of the clutch 3 Tc tends to increase proportionally. Although the valve opening V of the clutch control valve CCV is 3 positions in the figure, the spool valve slightly strokes at an intermediate opening (valve opening 0 mm) other than fully open and fully closed in practice, and the clutch pressure Pc is reduced. It can be changed continuously.
[0024]
Although there is a control system for the lock-up clutch 7 in this embodiment, the description is omitted here because it is not directly related to the present invention. The configuration of the hydraulic control system is substantially the same as the hydraulic control system of the wet multi-plate clutch 3.
[0025]
Next, an electronic control device for electronically controlling the power transmission device will be described with reference to FIG. In addition to the clutch solenoid valve CSV, various switches and sensors are connected to the ECU 16 in order to electronically control the apparatus. This includes an engine speed sensor 18 for detecting the engine speed, a turbine speed sensor 19 for detecting the speed on the input side of the clutch 3, that is, the speed of the turbine 5, the speed of the transmission T / M, representative Specifically, a transmission rotation sensor 20 for detecting the rotation speed of the input auxiliary gear 12 and a vehicle speed sensor 21 for detecting the vehicle speed are included. These sensors are also shown in FIG. Further, a parking brake switch 22 for detecting whether or not the parking brake is operating, a foot brake switch 23 for detecting whether or not the foot brake is operating, and a gear position for detecting the gear position of the transmission. A sensor 24, an oil temperature sensor 27 for detecting the oil temperature of the clutch control oil, a voltmeter 28 for detecting the battery voltage, and an accelerator opening sensor for detecting the amount of depression of the accelerator pedal (accelerator opening) 29 is also included.
[0026]
A knob switch 25 is also connected to the ECU 16. That is, in this embodiment, in order to detect the start timing of the shift operation by the driver or to determine the timing to start the clutch disengagement, the shift knob of the cab can slightly swing in the shift direction with respect to the lever. The knob switch 25 is provided between the lever and the shift knob. When the shift operation is performed by the driver, if the shift knob swings prior to the operation of the lever, the knob switch 25 is turned on, and this is a signal to start the clutch disengagement. The specific configuration is the same as that shown in JP-A-11-236931.
[0027]
In addition, the power transmission device of the present embodiment is provided with a slope start assist device (HSA; Hill Start Aid) as shown in the publication, and in the cab to manually turn on and off the device. An HSA switch 26 is provided, and the HSA switch 26 is connected to the ECU 16. The HSA switch 26 also serves as a trigger switch for starting torque learning according to the present invention. In the present invention, the HSA itself has little meaning.
[0028]
Next, the operation of the power transmission device according to this embodiment will be described.
[0029]
In this power transmission device, the power of the engine E is transmitted in the order of the fluid coupling 2, the wet multi-plate clutch 3, and the transmission T / M. In principle, the lock-up clutch 7 is always turned on (contacted) during traveling after starting, and turned off (disconnected) only when the vehicle is stopped. Therefore, the creep of the fluid coupling 2 can be used at the time of starting, and the control becomes simpler than that in which the friction clutch is electronically controlled to start, and the fluid coupling 2 is locked up during traveling, so that loss due to slip can be prevented. . The wet multi-plate clutch 3 is connected / disconnected at every shift. This is the same as a normal MT car.
[0030]
First, the operation when starting the vehicle will be described. When the vehicle is stopped in gear neutral, the driver tries to start and operates the shift lever to the start stage. Then, in the shift lever, the knob switch 25 is turned on when the shift knob swings prior to the operation of the lever, and the clutch 3 is cut off as a signal. When the shift lever is subsequently operated, the transmission T / M is geared into the starting stage, and when this is detected by the gear position sensor 24, the clutch 3 is connected. Since the turbine 5 is stopped from the drive wheel side by this connection, the pump 4 slides with respect to the turbine 5 and a creep force is generated. Therefore, if the brake is released or the accelerator is depressed, the vehicle starts to move.
[0031]
Next, the operation at the time of shifting while the vehicle is running will be described. When the vehicle is traveling at a predetermined gear stage, it is assumed that the driver tries to operate the shift lever to the next gear stage in order to shift. Then, prior to the operation of the lever, the shift knob swings, the knob switch 25 is turned on, and the clutch 3 is disconnected with this as a signal. Then, when the shift lever is continuously operated, the transmission T / M is geared into the next shift stage, and when this is detected by the gear position sensor 24, the clutch 3 is connected. This completes the shift. During this shift, the lockup clutch 7 remains on, and the engine power is transmitted to the clutch 3 as it is.
[0032]
Incidentally, the clutch 3 is connected at a high speed (rapid contact) from the complete disconnection to the vicinity of the torque point, and at a low speed (slow connection) from the vicinity of the torque point. By switching the connection speed in this way, both connection shock reduction and connection time reduction are achieved.
[0033]
It is important to know the position at which the clutch starts to be engaged, in other words, the torque point that is the point at which the predetermined torque can be transmitted first. This is because the connection speed switching point is determined based on this torque point.
[0034]
The torque point has individual differences and variations for each clutch and cannot be uniquely determined. In the present embodiment, as shown in FIG. 3, even if the same duty pulse is given, the clutch torque capacity diagram is almost shifted as shown by the arrow. Therefore, it is necessary to learn the torque point for each clutch or each vehicle. In the case of controlling a conventional dry friction clutch, the torque point can be determined by the clutch stroke. However, the wet multi-plate clutch as in the present invention does not originally have a concept of stroke, and therefore cannot adopt a similar method.
[0035]
Therefore, in this apparatus, the duty value of the duty pulse output by the ECU 16 itself is used as the torque point learning value. This will be described in detail below.
[0036]
FIG. 5 is a time chart showing the contents of torque point learning control. (a) shows the duty pulse output from the ECU 16, (b) shows how the duty D changes, and (c) shows the clutch stroke of the wet multi-plate clutch 3 virtually for easy understanding. (D) shows the state of change between the rotational speed of the engine E (engine rotational speed Ne) and the rotational speed of the turbine 5 (turbine rotational speed Nt). As shown in (a), the time period of the torque learning control is Δt, and in this embodiment, Δt = 20 (msec).
[0037]
First, it is assumed that a predetermined learning condition is satisfied at time t1. At this time, the duty D = 100 (%), and the clutch is disengaged. Therefore, the turbine 5 rotates with the pump 4, and the turbine speed Nt matches the engine speed Ne. Thereafter, when a predetermined learning start condition is satisfied at time t2, learning is started. Initially, the duty D is relatively reduced to the close side, and the starting duty D0 = 60 (%). This is to shorten the learning time. Of course, the value of the start duty D0 is determined so that the target torque point is never reached even if the clutch is varied, however, as close as possible to the torque point. In other words, D = 100-60 (%) can be said to be an invalid area (play) in all clutches, and the aim here is to shorten the learning time by connecting such invalid areas at once. .
[0038]
According to FIG. 3, the torque capacity remains zero when the duty D is changed from 100 (%) to 60 (%). Therefore, it is a good idea to connect such invalids at once. The start duty D0 is predetermined based on experimental data as shown.
[0039]
After the output of the start duty D0, the start duty D0 is held for a certain time Δt2 = 0.5 (sec), and after the time Δt2 has elapsed, the output of the slow contact duty D1 is started. That is, after the start duty D0 is output, the output of the slow contact duty D1 is started after a certain time Δt2.
[0040]
Even if the start duty D0 is output, the clutch piston is not pressed until the clutch piston has made a minute stroke (about 2 mm), so it takes a certain amount of time to obtain a connection state commensurate with the start duty D0. . Conversely, a connection state commensurate with the start duty D0 cannot be obtained within a short time of Δt = 20 (msec). Because of such a response delay, if the output of the slow contact duty is started immediately after the start duty is output (from the next control cycle), the response delay is always dragged during the slow contact, which is true during learning. There is a risk of learning a value closer to the torque point. This leads to a problem of a large clutch connection shock because a learning value shifted toward the contact side is used even in normal clutch connection control.
[0041]
Therefore, if the start duty D0 is maintained after the output of the start duty D0 and the output of the slow contact duty D1 is started after the elapse of a fixed time Δt2 = 0.5 (sec) longer than the control period Δt = 20 (msec), the time Δt2 Since the clutch stroke can be started after the initial stroke of the clutch piston is completed and the connection state corresponding to the start duty D0 is obtained, an accurate learning value corresponding to the true torque point is absorbed. Thus, a large connection shock can be prevented even in normal clutch engagement control. The time Δt2 = 0.5 (sec) is an example and can be changed as appropriate.
[0042]
Next, when the connection up to the point before the torque point is finished, the connection width for each cycle is reduced to extremely reduce the clutch connection speed. That is, as shown in FIG. 5, the amount of decrease in duty for each period is set to step duty Ds (0.048 (%) in this embodiment), and the duty D is decreased by Ds for each control cycle. The duty D of each control round is a value obtained by subtracting the step duty Ds from the previous value, and this is the slow contact duty D1.
[0043]
When the clutch is connected (slowly connected) little by little in this way, the turbine speed Nt falls with respect to the engine speed Ne. That is, the output side of the clutch cannot be rotated because the output side of the transmission is stopped by the brake while the gear of the transmission is engaged. In contrast, the pump 4 is still driven by the engine E. Therefore, when the clutch is connected, the rotational speed is gradually lowered so that the input side of the clutch, that is, the turbine 5 stops, and at the same time, the slip between the pump 4 and the turbine 5 gradually increases, and the turbine rotational speed is increased. Nt gradually falls with respect to the engine speed Ne.
[0044]
Therefore, when the difference ΔN = Ne−Nt between these rotational speeds reaches the predetermined value Nm, the ECU 16 learns the value of the duty D at this time as the torque point learning value Dm. In this embodiment, Nm = 300 (rpm). More specifically, the ECU 16 detects the engine rotation speed Ne detected by the engine rotation sensor 18 and the turbine rotation sensor 19 in the process of slowly engaging the clutch by decreasing the duty D by the step duty Ds. When the difference ΔN = Ne−Nt with the turbine rotational speed Nt becomes equal to or greater than the predetermined value Nm, the value of the duty D of the duty pulse sent by the ECU 16 at this time is once taken into the ECU 16 and corrected, and the torque point The learning value Dm is stored in a memory in the ECU 16.
[0045]
The duty is taken in after waiting for a predetermined time after detecting that the rotation difference ΔN is equal to or greater than the predetermined value Nm. That is, even if ΔN ≧ Nm is detected, it may be temporary due to the influence of noise or the like, and if detection and capture is performed up to such a case, it is based on an inaccurate value. Learning is performed, and the subsequent clutch control is hindered.
[0046]
Therefore, if ΔN ≧ Nm still holds even after waiting for a certain time from the detection, the fact is regarded as correct and the duty is taken in. Thereby, highly reliable learning can be performed.
[0047]
Specifically, since ΔN ≧ Nm is detected, a predetermined waiting time Δt1 = 1 (sec) that is longer than the normal control period Δt = 20 (msec) while maintaining the value of the duty D at that time If ΔN ≧ Nm again at the elapse of the waiting time Δt1, the held duty value is taken in. This is a method of taking in if ΔN ≧ Nm at the beginning and end of the waiting time Δt1. Apart from this, if ΔN ≧ Nm is always satisfied during the waiting time Δt1, there is also a method of taking in. In any case, the intake is performed after a lapse of a certain time Δt1 longer than the predetermined period Δt from the detection of the drop of the predetermined rotation speed Nm with respect to the engine rotation speed Ne of the turbine rotation speed Nt. Here, the waiting time Δt1 = 1 (sec) is an example, and the length of the waiting time can be changed as appropriate.
[0048]
When the duty has been taken in, correction is performed. The reason for the correction is as follows. That is, the clutch pressure output from the clutch control valve CCV varies depending on the oil temperature of the control oil and the battery voltage applied to the clutch solenoid valve CSV. Further, the transmission torque capacity of the fluid coupling 2 varies depending on the engine speed. Therefore, if the learning value is determined without taking these values into consideration, the learning value varies depending on the vehicle condition at the time of learning, and the subsequent clutch control is hindered.
[0049]
Correction is performed as follows. First, a correction method based on the oil temperature of the clutch control oil will be described with reference to FIG. In FIG. 8, (a) is experimental data showing the relationship between the oil temperature and the clutch pressure when the duty is constant (for example, 50%). When the reference temperature is set to 70 ° C., the clutch pressure decreases as the oil temperature deviates from the reference temperature. This means that the clutch shifts to the disengagement side even if the same duty is output.
[0050]
Therefore, the duty is corrected according to the map shown in (b). This map defines the duty correction value Dto for the oil temperature based on the experimental data of (a), and is stored in the ECU 16. According to this, when the oil temperature deviates from the reference temperature, the correction value Dto takes a positive value. The correction value Dto is read from the oil temperature at the time of learning according to the map of (b), and this is added to the acquired duty D. In this way, the learning value can be shifted to the large duty side, that is, the disconnection side by the amount that the clutch has shifted to the disengagement side due to the displacement of the oil temperature with respect to the reference temperature, and correction according to the oil temperature becomes possible.
[0051]
Correction based on the battery voltage and the engine speed is performed in the same manner. A correction method based on the battery voltage will be described with reference to FIG. In FIG. 9, (a) is experimental data showing the relationship between the battery voltage and the clutch pressure when the duty is constant (for example, 50%). When the reference voltage is 28V, the clutch pressure decreases as the battery voltage becomes higher than the reference voltage, and the clutch pressure increases as the battery voltage becomes lower than the reference voltage. The former means that the clutch shifts to the disengagement side even if the same duty is output, and the latter means that the clutch shifts to the contact side even if the same duty is output.
[0052]
Therefore, the duty is corrected according to the map shown in (b). This map defines the duty correction value Dv for the battery voltage based on the experimental data of (a), and is stored in the ECU 16. According to this, when the battery voltage deviates from the reference voltage to the large side, the correction value Dv takes a positive value, and when the battery voltage deviates from the reference voltage to the small side, the correction value Dv takes a negative value. The correction value Dv is read from the battery voltage at the time of learning according to the map of (b), and this is added to the acquired duty D. In this way, the learning value can be shifted to the large duty side, that is, the disconnected side by the amount that the battery voltage has shifted to the large side with respect to the reference voltage and the clutch has shifted to the disconnected side. Further, the learning value can be shifted to the small duty side, that is, the contact side by the amount that the battery voltage is shifted to the small side with respect to the reference voltage and the clutch is shifted to the contact side. In this way, correction according to the battery voltage becomes possible.
[0053]
Next, a correction method based on the engine speed will be described with reference to FIG. In FIG. 10, (a) is experimental data showing the relationship between the engine speed and the transmission torque capacity in the fluid coupling 2. When the reference speed is set to idle speed = 600 (rpm), the transmission torque capacity increases as the engine speed becomes higher than the reference speed, and the transmission torque capacity decreases as the engine speed becomes lower than the reference speed. . In the former, the fluid coupling 2 becomes less slippery as the engine speed is higher than the reference speed, and the difference ΔN between the engine speed Ne and the turbine speed Nt is less likely to be generated, that is, smaller than the reference speed during learning ( If the duty of the value on the tangential side is not output, ΔN does not exceed Nm. The latter is the opposite.
[0054]
Therefore, the duty is corrected according to the map shown in (b). This map defines the duty correction value Dne for the engine speed based on the experimental data of (a), and is stored in the ECU 16. According to this, the correction value Dne takes a negative value when the engine speed deviates from the reference speed to the large side, and the correction value Dne takes a positive value when the engine speed deviates from the reference speed to the small side. The correction value Dne is read from the engine speed at the time of learning according to the map of (b), and is added to the acquired duty D. In this way, when the engine speed at the time of learning shifts to the large side with respect to the reference speed (during the execution of fast idle, etc.), the learning value is reduced to the small duty side, that is, the contact side by the amount that the fluid coupling 2 becomes less slippery. On the other hand, when the engine speed at the time of learning shifts to the small side with respect to the reference speed, it can be shifted to the opposite side. In this way, correction according to the engine speed is possible.
[0055]
Eventually, the correction is performed by adding Dto, Dv, and Dne to the acquired duty D, and the value after addition or correction is stored in the ECU 16 as the final learned value Dm.
[0056]
In the present embodiment, correction is performed using all three correction values Dto, Dv, and Dne, but correction may be performed using one or two of them. The correction reference value (for example, 70 ° C. at the oil temperature) can be set to any value other than the above. Various correction parameters other than the oil temperature of the clutch control oil, the battery voltage, and the engine speed can be considered.
[0057]
Now, when the storage of the torque point learning value Dm is completed in this way, the learning is substantially ended, and thereafter, the clutch is disconnected and all the learning control (learning mode) is ended.
[0058]
Referring to FIG. 3, for example, assuming that the rotation difference ΔN first exceeds a predetermined value Nm when the duty D = 50 (%), the torque capacity of the clutch 3 at this time is Tcm = about 200 (Nm). Yes, this is the torque point. Even if the torque capacity diagram deviates due to variations in the clutch, etc., the torque capacity and the rotational difference ΔN are in a unique relationship. Therefore, if the duty D indicating the same rotational difference Nm is detected, the point indicating the same torque capacity Tcm is obtained. Can be detected. As a result, a constant torque point can always be detected and learned regardless of individual differences in the clutch.
[0059]
As described above, according to the present learning method, it is possible to preferably learn the torque point even in the wet multi-plate clutch, and it is possible to accurately grasp the torque point different for each clutch and use it for various clutch controls such as connection speed switching. . Then, variations in the clutch and its control device and individual differences are absorbed, and the wet multi-plate clutch can be connected with the same feeling in any vehicle.
[0060]
In addition, since the output of the slow engagement duty starts after a lapse of a certain time after the output of the start duty, the response delay during clutch engagement can be absorbed and an accurate learning value can be learned. Can be prevented.
[0061]
Furthermore, since the duty is taken in after a predetermined time has elapsed since the detection of the drop in the predetermined speed relative to the engine speed of the turbine speed, the reliability is improved. Since the acquired value is corrected to be a learned value, a value in a constant reference state can always be learned regardless of the driving situation at the time of learning.
[0062]
By the way, the outline of the normal clutch connection control after learning the torque point in this way is as follows. That is, from the clutch complete state with the duty D = 100 (%), a duty slightly greater (a larger value) than the torque point learning value Dm is first suddenly applied to the clutch solenoid valve CSV. One-shot contact control. As a result, the ineffective portion of the clutch is suddenly contacted, and the connection time can be shortened. Then, after waiting for a certain time in this state, the duty is subtracted by a small step duty. As a result, the clutch is loosely connected and a clutch engagement shock is prevented.
[0063]
Next, the details of the torque point learning control will be described in detail with reference to FIG. FIG. 6 is a state transition diagram showing the transition of the clutch control phase.
[0064]
Torque point learning can be performed arbitrarily according to the driver's intention. When the driver wants to learn, the driver first operates the shift lever to neutral (N). In this apparatus, since the clutch is disengaged when the gear neutral is in the normal control of the clutch and the clutch is engaged when the gear is in, the clutch is automatically disengaged by operating the shift lever to N.
[0065]
This state is referred to as a clutch completion phase 101 shown in FIG. That is, at this time, the ECU 16 outputs the duty D0 = 100 (%), and the clutch is completely disengaged.
[0066]
Next, when a predetermined condition is satisfied from this state, the learning mode is entered, and the learning completion phase 102 is entered. The transition condition T1 at this time is
▲ 1 ▼ Vehicle stop (vehicle speed = 0km / h)
▲ 2 ▼ Transmission T / M is neutral
(3) Engine E is near idle speed (Ne = 300 to 800 rpm, idle speed of this embodiment = 600 rpm)
▲ 4 ▼ During parking brake operation
▲ 5 ▼ During foot brake operation
Are all satisfied, and in this state
(6) HSA switch 26 is turned on
That is. Even in this phase, the clutch is completely disengaged, that is, the duty D0 = 100 (%) is continuously output from the ECU 16, and the disengagement of the clutch is maintained. Since the foot brake is depressed from the condition (5), the accelerator is in a released state, and the condition (4) is normally satisfied unless the engine is operating at an extremely high first idle operation. Other conditions can be appropriately added as the transition condition T1.
[0067]
The satisfaction of the learning condition at time t1 in FIG. 5 means that the above transition condition T1 is satisfied. In FIG. 5, the clutch is disengaged by the clutch disengagement phase 101 before time t1, and the clutch is disengaged by the learning completion phase 102 after time t1.
[0068]
Next, when the transition condition T <b> 2 is satisfied from the learning completion phase 102, the learning transition phase 103 is entered. Transition condition T2 is
(1) Transmission T / M is geared in to 2nd gear
That is. That is, when the driver shifts to the second speed from the state of the learning complete phase 102, the operation shifts to the learning slow engagement phase 103, and the clutch engagement is automatically started. In other words, the shift operation to the second speed is a signal to start learning. Note that this transition condition T2 can be changed to another condition or added as appropriate. The second speed is an example, and in short, the output side of the clutch only needs to be stopped by a brake, so that the gear can be any speed. However, it is a condition that the gear is in any gear. In the present embodiment, since the vehicle (truck or the like) frequently uses the second speed start, learning is also performed at the second speed because it is close to the actual.
[0069]
Satisfaction of the learning start condition at time t2 in FIG. 5 means that this transition condition T2 is satisfied. As shown in FIG. 5, in the learning slow engagement phase 103, the start duty D0 = 60 (%) is first output from the ECU 16 to engage the clutch relatively large, and the start is started for a certain time Δt2 = 0.5 (sec). After maintaining the duty D0 = 60 (%), the duty D is lowered by step duty Ds = 0.048 (%) for each control cycle, and the clutch is loosely engaged.
[0070]
When the transition condition T3 is satisfied from the learning slow connection phase 103, the learning stop phase 104 is started. Transition condition T3 is
(1) The rotational difference ΔN = Ne−Nt between the engine rotational speed Ne and the turbine rotational speed Nt has become a predetermined value Nm = 300 (rpm) or more.
It is. In the learning stop phase 104, the duty D when (1) is satisfied is held for the waiting time Δt1 = 1 (sec), the clutch is held at the current state, and at the same time as the waiting time Δt1 elapses, It is determined whether or not the condition 1 ▼ is satisfied. If it is satisfied, the value of the duty D is temporarily taken into the ECU 16 for the time being. Then, it is determined whether this value is a normal value as a learning value by comparing it with a predetermined condition. If it is normal, the value is corrected as described above, and updated learning is performed as a new learning value Dm. At this time, the old learning value already stored is deleted.
[0071]
It should be noted that conditions other than (1) can be adopted as appropriate for this transition condition T3. The condition of (1) is that if the engine is idling speed = 600 (rpm)
(1) In other words, it can be said that the turbine rotational speed Nt is equal to or less than ½ of the engine rotational speed Ne. The condition of (1) is
(1) When the engine speed Ne drops to the specified speed
It can be replaced with the condition. The reason for this is that the engine learning speed Ne is also lowered due to the drop of the turbine rotation speed Nt, so that the torque learning point may be determined by checking the drop of the engine rotation speed Ne. For example, the drop amount of the engine speed Ne is set to 50 (rpm).
[0072]
Next, when the transition condition T4 is satisfied from the learning stop phase 104, the process proceeds to the learning end phase 105. Transition condition T4 is
(1) Learning of torque point learning value Dm has been completed normally
In addition to the condition
▲ 2 ▼ The vehicle started to move (vehicle speed ≠ 0km / h)
▲ 3 ▼ The 1st, 3rd and 5th speed knob switches are turned on
▲ 4 ▼ Engine speed is not near idle speed (Ne <300rpm or> 800rpm)
▲ 5 ▼ Parking brake is not activated
▲ 6 ▼ Foot brake is not activated
One of the conditions is established. In particular, (2) to (6) mean that the state is not suitable for learning execution. When these conditions are satisfied, even in the learning completion phase 102 and the learning slow connection phase 103, the learning end phase 105 Migrate to That is, the transition conditions T6 and T5 from the learning completion phase 102 and the learning slow connection phase 103 to the learning end phase 105 are equal to T4. There are various other conditions that are inappropriate for such learning execution.
[0073]
In the learning end phase 105, the ECU 16 outputs a duty D0 = 100 (%) to complete the clutch. This output establishes the transition condition T7, exits the learning mode, returns to the normal control, and reaches the control stop mode 106. In the control stop mode 106, the duty D0 = 100 (%) is maintained to maintain the clutch completeness. However, the situation is different from the normal state in which the clutch is disengaged although the gear is in the second speed. However, the driver returns to normal control when the gear is neutral.
[0074]
The details of the torque point learning control have been described above. Next, contents of normal clutch engagement control and correction of the control value based on the torque point learning value obtained in this way will be described.
[0075]
FIG. 7 is a time chart showing the contents of clutch engagement control. The horizontal axis is time t, and the vertical axis is the duty D output from the ECU 16. The solid line is a base diagram before correction, and the alternate long and short dash line is a diagram after correction of two patterns (after correction 1, 2).
[0076]
First, the contents of normal clutch engagement control in the base will be described. First duty duty that is output first from the complete state (D = 100 (%)), that is, start duty Dst0, end duty Ded0 that determines the end of clutch loose engagement, and step duty Ds0 that is a duty reduction width at the time of clutch loose engagement Are selected from a map stored in the ECU 16 in advance. The map is created based on tests and the like in advance so as to obtain respective optimum values reflecting the driving state of the vehicle (accelerator opening degree, gear stage, vehicle speed, shift up / down, etc.). The base value of the torque point learning value is determined in advance as Dtb and stored in the ECU 16. Here, Dtb = 53.5 (%).
[0077]
In the normal clutch engagement control, the start duty Dst0 is output after first outputting the start duty Dst0 from the complete state (D = 100 (%)) and connecting the clutch to the point before the torque point (one-shot engagement) as in the learning. Is maintained for a certain time Δt3, and thereafter, the output of the slow engagement duty Dk is started, and the duty is decreased step by step Ds0 to perform the gentle engagement with the half clutch. When the end duty Ded0 is reached, D = 0 (%) is output and the clutch is completely engaged. As can be seen from the figure, the start duty Dst0 is a value slightly disengaged (large) from the base value Dtb of the torque point learning value, whereby the clutch is connected all the way to the torque point.
[0078]
The control cycle is the same as Δt = 20 (msec). The decrease period Δts of the slow contact duty Dk by the step duty Ds0 may be equal to the control period Δt or may be equal to a plurality of periods (for example, 3 periods = 3Δt). In comparison, the waiting time Δt3 after the start duty is longer. For example, Δt3 is 0.2 (s) at the time of shifting up and 0.5 (s) at the time of shifting down. As a result, after the start duty is output, the slow engagement is started after a sufficient waiting time Δt3 has elapsed, so that the clutch response delay can be absorbed as in the learning. When the decrease cycle Δts of the slow contact duty Dk is made equal to the plurality of control cycles nΔt, the value of n may be selected from the map.
[0079]
The step duty Ds0 is set to a value larger than the step duty Ds at the time of learning, and the clutch is loosely engaged at a normal time faster than at the time of learning. At the time of learning, the entire connection time is about 5 to 6 seconds, and the connection is made over a relatively long time, but the normal time is about 1 to 3 seconds.
[0080]
Next, after correction 1 will be described. The correction is based on the update of the torque point learning value and the correction based on the change in the vehicle situation. First, it is assumed that the torque point learning value is updated to Dlt1 smaller than the base value Dtb by executing torque point learning. Then, the start duty and the end duty are corrected as follows (first correction stage).
[0081]
That is, first, the difference ΔDse = Dst0−Ded0 between the start duty Dst0 and the end duty Ded0 that defines the half clutch engagement range, and the difference A = Dtb−Dlt1 (> 0) between the base value Dtb of the torque point learning value and the update value Dlt1 ) Is calculated. Then, the corrected start duty Dst1 ′ is expressed by the equation
Dst1 ′ = Dst0−A
To calculate the corrected end duty Ded1 ′
Ded1 ′ = Dst1′−ΔDse
Calculate based on
[0082]
Next, a correction based on a change in the vehicle situation is performed (second correction stage). This correction is performed for the following reason. That is, the torque point learning values Dtb and Dlt1 are values in a fixed reference state (clutch control oil temperature = 70 ° C., battery voltage = 28 V, engine speed = 600 rpm), but when actual clutch engagement control is performed. It does not necessarily match the reference state. Therefore, the amount of deviation from the reference state is corrected, and the clutch connection feeling is kept constant as intended.
[0083]
Correction is performed in the same manner as during learning. First, for correction based on the oil temperature of the clutch control oil, the duty correction value Dto corresponding to the oil temperature during clutch engagement control is read from the map of FIG. However, here, the calculation is reverse to that at the time of learning, and the duty correction value Dto is subtracted from the start duty Dst1 ′ and the end duty Ded1 ′ after learning correction. This is because, for example, when the oil temperature is lower than the reference temperature = 70 ° C., the clutch pressure is lowered and the clutch is difficult to be connected. Therefore, the positive duty correction value Dto is subtracted accordingly, and the clutch is connected excessively.
[0084]
As for the correction based on the battery voltage, the duty correction value Dv corresponding to the battery voltage at the time of clutch engagement control is read from the map of FIG. In this case as well, the calculation is opposite to that at the time of learning, and the duty correction value Dv is subtracted from the start duty Dst1 ′ and the end duty Ded1 ′ after learning correction. This is because, for example, when the battery voltage is lower than the reference voltage = 28V, the clutch pressure rises and the clutch is easily connected. Therefore, the negative duty correction value Dv is subtracted by that amount (that is, the duty itself increases), and the clutch is connected. I will reduce the amount.
[0085]
For the correction based on the engine speed, the duty correction value Dne corresponding to the engine speed at the time of clutch engagement control is read from the map of FIG. In this case as well, the calculation is the reverse of the learning, and the duty correction value Dne is subtracted from the start duty Dst1 ′ and the end duty Ded1 ′ after learning correction. This is because, for example, when the engine speed is higher than the reference speed = 600 rpm, the input torque of the clutch increases and the output torque increases accordingly, so the negative duty correction value Dne is subtracted (that is, the duty itself increases), and the clutch The amount of connections will be reduced. The correction based on the engine speed is mainly for the purpose of preventing a garage shock at the start. For this reason, the upper limit of the engine speed is set to a low value of 1000 rpm in the map of FIG.
[0086]
As a result, correction is performed by subtracting Dto, Dv, and Dne from the start duty Dst1 ′ and the end duty Ded1 ′. FIG. 7 shows an example in which Dto + Dv + Dne = A ′> 0, and the start duty Dst1 ′ and the end duty Ded1 ′ are corrected to the small duty side (contact side). The final values Dst1 and Ded1 thus obtained are the start duty and end duty of 1 after correction, and the post-correction 1 diagram is obtained by translating the base diagram to the clutch contact side. Note that the value of the step duty Ds0 is not corrected.
[0087]
In the present embodiment, correction is performed using all three correction values Dto, Dv, and Dne, but correction may be performed using one or two of them. Various correction parameters other than the oil temperature of the clutch control oil, the battery voltage, and the engine speed can be considered. In this embodiment, the correction based on the torque point learning is performed first and the correction based on the vehicle situation is performed later, but these may be performed simultaneously or vice versa. In practice, the above calculation is performed at the same time and corrected at one time.
[0088]
The above correction is performed every time the clutch engagement control is executed. Since the difference A between the base value Dtb and the update value Dlt1 of the torque point learning value is the same until the next learning, it is preferable to store this value in the memory and take it out for each control.
[0089]
After the correction 2, the torque point learning value update value Dlt2 ′ is larger than the base value Dtb (difference absolute value B), and the duty correction value sum B ′ based on changes in the vehicle situation becomes a negative value. It is. The diagram moves parallel to the large duty (disconnected) side with respect to the base. In this case, correction is performed in the same manner as described above. The base start duty Dst0 and the end duty Ded0 are corrected to Dst2 ′ and Ded2 ′ by the correction based on the update of the torque point learning value, and then Dst2 ′ and Ded2 ′ are corrected to Dst2 and Ded2 by the correction based on the change in the vehicle situation. The
[0090]
As described above, according to the present invention, since the start duty is corrected based on the predetermined correction parameter related to the vehicle situation, it is possible to prevent instability of the clutch connection feeling and thus the shift feeling caused by the variation in the vehicle situation. be able to. Here, although the end duty is also corrected in the present embodiment, it is the start duty at which torque transmission is first started that greatly affects the clutch connection feeling, and this correction is effective. Of course, it is also preferable to correct the end duty. This is because, as shown in FIG. 7, the diagram is translated in accordance with the vehicle situation, and the contact control as intended is reproduced.
[0091]
The embodiment of the present invention is not limited to the above. The wet friction clutch referred to in the present invention is a multi-plate type in the above embodiment, but may be a single-plate type, for example. In addition, the fluid pressure referred to in the present invention is a hydraulic pressure in the above embodiment, but other fluid pressures such as pneumatic pressure may be used. The transmission according to the present invention is a constant mesh type manual transmission in the above embodiment, but may be a constant mesh type automatic transmission or a planetary gear type automatic transmission such as an AT car. The engine can be of any type such as diesel or gasoline. Each of the above numerical values can be changed as appropriate.
[0092]
【The invention's effect】
As described above, according to the present invention, an excellent effect is exhibited that it is possible to prevent instability of the clutch connection feeling and thus the shift feeling caused by the variation in the vehicle situation.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram showing a power transmission device for a vehicle according to an embodiment of the present invention.
FIG. 2 is a hydraulic circuit diagram showing a hydraulic pressure supply device according to an embodiment of the present invention.
FIG. 3 is a characteristic diagram of the hydraulic pressure supply device according to the embodiment of the present invention.
FIG. 4 is a configuration diagram illustrating an electronic control device according to an embodiment of the present invention.
FIG. 5 is a time chart showing the contents of torque point learning control according to the embodiment of the present invention.
FIG. 6 is a state transition diagram showing transition of a clutch control phase according to the embodiment of the present invention.
FIG. 7 is a time chart showing the contents of normal clutch engagement control according to the embodiment of the present invention.
8A is an experimental data showing the relationship between the oil temperature of the clutch control oil and the clutch pressure, and FIG. 8B is a map defining a duty correction value Dto for the oil temperature.
FIG. 9A is experimental data showing the relationship between battery voltage and clutch pressure, and FIG. 9B is a map that defines a duty correction value Dv for the battery voltage.
10A is experimental data showing the relationship between the engine speed and the transmission torque capacity of the fluid coupling, and FIG. 10B is a map that defines a duty correction value Dne for the engine speed.
[Explanation of symbols]
2 Fluid coupling
3 Wet multi-plate clutch
16 Electronic control unit (ECU)
21 Vehicle speed sensor
24 Gear position sensor
25 Knob switch
27 Oil temperature sensor
28 Voltmeter
29 Accelerator position sensor
E engine
T / M transmission
CSV clutch solenoid valve
CCV Clutch control valve
D Duty
Dtb, Dlt1, Dlt2 Torque point learning value
Dst0, Dst1, Dst2 Start duty
Dk Slow contact duty
Dto, Dv, Dne Duty correction value

Claims (2)

The working fluid pressure for driving the wet friction clutch connected to the vehicle's power transmission system is changed according to the duty of the duty pulse output from the electronic control unit, and transmission of power from the engine to the transmission is started. When the clutch position to be used is a torque point, the duty corresponding to the torque point is a torque point learning value, the torque point learning value is stored in the electronic control unit, and when the clutch is engaged from the disconnected state , A predetermined starting duty set near the torque point learning value stored in the electronic control unit and on the disengagement side is selected from the map and output from the electronic control unit, and then the predetermined loosening is performed so that the clutch is loosely engaged. Control of the clutch that outputs the contact duty from the electronic control unit every predetermined time In the method,
When a predetermined condition is satisfied, individual differences of the clutch, in order to absorb variations obtains the torque point learning value corresponding to the torque point during establishment the predetermined condition, the determined torque point learning value, the Correction based on a predetermined correction parameter related to the vehicle situation at the time when a predetermined condition is established, and update the torque point learning value stored in the electronic control unit with the corrected torque point learning value ,
On the other hand, when the clutch is engaged from the disengaged state, the start duty selected from the map is corrected based on the updated torque point learning value of the electronic control unit, and the vehicle condition during clutch control is corrected. A clutch control method, wherein correction is performed based on a predetermined correction parameter. 2. The clutch control method according to claim 1, wherein the correction parameter when the predetermined condition is satisfied and the correction parameter at the time of clutch control are the temperature of the working fluid, the battery voltage, or the engine speed.

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