JP2817631B2 - Clutch slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch slip control device, and more particularly to a technique for suppressing a change in transmission torque caused by a change in a friction coefficient caused by a change in a slip rotation speed.

[0002]

[Prior art]

(A) a clutch for transmitting the torque generated by the power source by frictional force; and (b) clutch driving means for engaging the clutch, wherein the driving force of the clutch driving means is slip-engaged so as to engage the clutch. There is a slip control device to control. For example, in an automatic vehicle having an automatic transmission, the engine output is transmitted to the automatic transmission through a fluid transmission such as a torque converter, but a lock-up clutch is provided in parallel with the fluid transmission. Along with providing the lock-up clutch in a predetermined slip state, for example, a slip rotation speed that is a rotation speed difference between an input-side rotation speed and an output-side rotation speed becomes a predetermined target slip rotation speed.
Japanese Patent Application Laid-Open No. 2-180365 proposes to control the driving force of a clutch driving means, for example, the hydraulic pressure of a hydraulic actuator. Such slip control prevents torque fluctuations and rotational speed fluctuations due to an engine explosion from being transmitted to a drive system such as an automatic transmission, and suppresses power loss due to a hydraulic transmission to improve fuel economy. Therefore, in an apparatus using a power source that generates periodic rotation speed fluctuations other than the engine, it is effective to perform similar clutch slip control in order to prevent transmission of rotation speed fluctuations and torque fluctuations. .

Here, the transmission torque of the clutch is T _LU , the equivalent friction radius of the clutch is R _LU , and the friction coefficient (dynamic friction coefficient).
, And the driving force of the clutch driving means is F, the transmission torque T _LU is expressed by the following equation (1), and the desired slip state, for example, the actual slip rotation speed Δω becomes the target slip rotation speed Δω _0. The driving force F is controlled.
Strictly speaking, the input-side rotation speed of the clutch fluctuates in accordance with the rotation speed of the power source.
If the control is performed so as to coincide with ω ₀ , the output rotation speed of the clutch fluctuates. In this case, the average slip rotation speed Δω _av ignoring minute rotation speed fluctuations such as a rotation speed difference within one rotation is calculated. And control it. Further, in the case where the output-side rotation speed such as the vehicle speed and the average rotation speed of the power source are both substantially constant in an equilibrium state to prevent transmission of torque fluctuation of the power source, the transmission torque T _{LU of the} clutch is
Regardless of the magnitude of the slip rotation speed Δω, it is controlled to be substantially the same as the average torque of the power source that does not include torque fluctuation. T _LU = R _LU × μ × F (1)

On the other hand, as the clutch driving means, a hydraulic actuator for engaging a clutch using hydraulic pressure as a driving force is widely used, and the hydraulic pressure can be continuously changed by duty control of an exciting current. In general, a linear solenoid type pressure regulating valve is provided. Such a linear solenoid type pressure regulator is
Excellent tracking performance is obtained due to its high responsiveness,
Since high-precision control is required and the cost is high, it has been considered to use an ON / OFF solenoid on-off valve that adjusts oil pressure by opening / closing according to ON / OFF signals.

[0005]

Although the equivalent friction radius R _LU is constant depending on the clutch, the friction coefficient μ is, for example, as shown in FIG. It changes according to the speed Δω, and if the driving force F is the same, the transmission torque T _LU changes. Since the slip rotation speed Δω fluctuates strictly with the fluctuation of the rotation speed of the power source such as the engine as described above, the friction coefficient μ fluctuates accordingly, while the driving force F
Is controlled based on the average slip rotation speed Δω _av , and eventually the transmission torque T _LU also fluctuates with the fluctuation of the slip rotation speed Δω, and a torque fluctuation occurs on the output side of the clutch. Therefore, the slip rotation speed Δ
range of the lower limit slip rotation speed Δω _X where the friction coefficient μ becomes substantially constant irrespective of the fluctuation of ω, for example, 50 rpm (5 /
Normally, the slip rotation is controlled at 6 s ^-1 ) or more. In FIG. 3, the friction coefficient μ increases as the slip rotation speed Δω decreases. However, depending on the type of the friction material of the clutch and the hydraulic oil, the slip rotation speed Δω decreases. The friction coefficient μ may decrease.

However, when the slip control is performed in a region where the slip rotation speed Δω is relatively large as described above,
There is a problem that the power loss is so large that the effect of improving the fuel efficiency cannot always be sufficiently obtained, and that the heat generation becomes large and the life of the clutch is shortened.

On the other hand, if the ON / OFF solenoid on / off valve is used when the clutch is engaged by the hydraulic actuator, the device can be constructed inexpensively and the control is easy. Thus, the hydraulic pressure is adjusted due to the opening and closing of the valve, and the transmission torque of the clutch fluctuates due to the hydraulic pressure fluctuation.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the fuel efficiency and clutch life even if the slip engagement is performed in a region where the slip rotation speed is low in order to improve the coefficient of friction. The purpose is to prevent the transmission torque from fluctuating due to the change. Another object of the present invention is to suppress fluctuation of the transmission torque of the clutch due to hydraulic pressure fluctuation accompanying opening / closing of the valve when adjusting the pressure using an inexpensive ON / OFF solenoid on-off valve.

[0009]

A first invention for solving the problems is as follows.
(A) a clutch for transmitting the torque generated by the power source by frictional force; and (b) clutch driving means for engaging the clutch, wherein the driving force of the clutch driving means is slip-engaged so as to engage the clutch. (C) slip rotational speed detecting means for detecting the slip rotational speed of the clutch, and (d) a slip rotational speed caused by a change in a friction coefficient accompanying the change in the slip rotational speed.
In response to the fluctuation of the slip rotation speed, the slip rotation speed
And a frictional driving force control means for fluctuating the driving force of the clutch driving means in opposition to the fluctuation of the friction coefficient accompanying the fluctuation of the degree .

[0010]

In such a clutch slip control device, the slip rotation speed is detected by the slip rotation speed detecting means, and the transmission torque fluctuates due to the fluctuation of the friction coefficient accompanying the fluctuation of the slip rotation speed. Suppression
Therefore , the frictional driving force control means responds to the fluctuation of the slip rotation speed and responds to the fluctuation of the slip rotation speed.
Contrary to the accompanying variation in friction coefficient, the driving force of the clutch drive means
Is varied. When the clutch driving means can control the driving force (oil pressure) at a frequency sufficiently higher than the torque fluctuation frequency of the power source, for example, as in a linear solenoid type pressure regulating valve, the frictional driving force control means is provided with a slip rotation. The correlation between the speed and the friction coefficient is stored in a storage unit such as a memory, and the friction coefficient is obtained in accordance with the slip rotation speed, and the driving force for obtaining a desired transmission torque is calculated from the above equation (1) or the like. Then, the clutch driving means may be controlled so as to obtain the driving force. Further, when a driving force (oil pressure) fluctuates in accordance with the opening and closing of the valve as in the case of an ON / OFF electromagnetic on-off valve, the driving force fluctuates in a manner opposite to the fluctuation of the friction coefficient accompanying the fluctuation of the slip rotation speed. , ON and OFF at the same frequency as the slip rotation speed fluctuation frequency
What is necessary is just to output a signal.

[0011]

As described above, according to the present invention, the transmission torque is prevented from fluctuating due to the fluctuation of the friction coefficient accompanying the fluctuation of the slip rotation speed. Even in a region where the coefficient changes and the slip rotation speed is small, the slip control is performed so that the torque does not change on the output side of the clutch due to the change in the friction coefficient. When the slip rotation speed is reduced in this manner, power loss and heat generation are reduced, and fuel efficiency and clutch life are improved.

[0012]

According to a second aspect of the present invention, in the clutch slip control device according to the first aspect of the present invention, the (b) clutch driving means includes (b-1) a hydraulic pressure as a driving force. A hydraulic actuator for engaging the
(B-2) a hydraulic control circuit provided with an ON / OFF solenoid on-off valve for adjusting the hydraulic pressure by being opened / closed in accordance with ON / OFF signals. (D-1) a duty control means for outputting the ON / OFF signal at a predetermined duty ratio for causing the clutch to slip-engage, and (d-2) an opposite to a change in the friction coefficient accompanying the change in the slip rotation speed. Output timing control means for outputting the ON / OFF signal at the same frequency as the slip rotation speed fluctuation frequency so that the driving force fluctuates.

[0013]

In such a clutch slip control device, the ON / OFF signal is output at a predetermined duty ratio by the duty control means, so that the ON / OFF signal is output.
The ON / OFF solenoid on-off valve is opened and closed according to the N and OFF signals, the hydraulic pressure of the hydraulic control circuit is adjusted, and the clutch is slip-engaged by the hydraulic actuator with a driving force corresponding to the hydraulic pressure. In that case, ON,
The hydraulic pressure fluctuates with the opening and closing of the OFF solenoid on-off valve, and the transmission torque also fluctuates with the fluctuation of the hydraulic pressure.
The ON and OFF signals for opening and closing the electromagnetic on-off valve are output from the output timing control means at the same frequency as the slip rotation speed fluctuation frequency so that the driving force fluctuates in the opposite direction to the friction coefficient fluctuation accompanying the slip rotation speed fluctuation. Therefore, the transmission torque fluctuation caused by the hydraulic fluctuation caused by the opening and closing of the ON / OFF solenoid on-off valve and the transmission torque fluctuation caused by the fluctuation of the friction coefficient cancel each other, and the fluctuation of the transmission torque is suppressed.

[0014]

As described above, in the second invention as well, the fluctuation of the transmission torque due to the fluctuation of the friction coefficient accompanying the fluctuation of the slip rotation speed is suppressed. Similar effects can be obtained. Moreover, in the present invention, the transmission torque fluctuation caused by the variation of the friction coefficient is suppressed by utilizing the oil pressure fluctuation caused by the opening and closing of the ON / OFF solenoid on-off valve. It is suppressed at the same time, and it is inexpensive and easy to control.
The accuracy of transmission torque control using the N, OFF solenoid on-off valve is improved.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a vehicle power transmission device to which an embodiment of the second invention is applied. An engine torque generated by an engine 10 as a power source is controlled by a torque converter 12 with a lock-up clutch, an automatic transmission 14. And transmitted to a differential gear device and drive wheels (not shown). The torque converter 12 corresponds to a hydraulic power transmission, and includes a pump impeller 18 connected to a crankshaft 16 of the engine 10, a turbine impeller 22 fixed to an input shaft 20 of the automatic transmission 14, and A stator wheel 28 fixed to a housing 26 which is a non-rotating member via a directional clutch 24, and amplifies engine torque at an amplification factor corresponding to an input / output rotation speed ratio and transmits the amplified engine torque to the automatic transmission 14. I do. The torque converter 12 is provided integrally with a lock-up clutch 30 that directly connects the crankshaft 16 and the input shaft 20 by the frictional force of the friction plate, and a hydraulic actuator 32 that engages and releases the lock-up clutch 30. ing. Hydraulic actuator 32
The piston 34 is connected to the input shaft 20 so as to be movable in the axial direction and relatively unrotatable about the axis, and the engagement-side oil chamber 36 and the release-side oil chamber 38 formed on both sides of the piston 34 in the axial direction. And the engagement hydraulic pressure P of the engagement side oil chamber 36
_When the release hydraulic pressure P _OFF of the release side oil chamber 38 is higher than _ON , the lock-up clutch 30 is released, and the engine torque is transmitted exclusively through the torque converter 12, while the engagement hydraulic pressure is higher than the release hydraulic pressure P _OFF When P _ON is increased, the lock-up clutch 30 applies its differential pressure ΔP (= P _ON
−P _OFF ), and is engaged from the crankshaft 16 through the lock-up clutch 30 to the input shaft 20.
The engine torque is transmitted directly to the engine. Also,
The automatic transmission 14 is a stepped type equipped with a plurality of planetary gear units, clutches, brakes, and the like. When the engagement state of the clutch or brake is switched, the rotation of the input shaft 20 is shifted at a predetermined gear ratio. And output from the output shaft 40.

The pressure difference ΔP of the hydraulic actuator 32 is regulated by a hydraulic control circuit 44. Hydraulic control circuit 4
4 includes a lock-up relay valve 46, a lock-up control valve 48, and an ON / OFF electromagnetic on-off valve 50. The lock-up relay valve 46 is switched to a state on the right side in the figure by a lock-up switching control device (not shown). As a result, the line oil pressure P _L of the oil pressure source 2 is supplied to the release-side oil chamber 38 as the release oil pressure P _{OFF and the} hydraulic oil in the engagement-side oil chamber 36 is drained, so that the lock-up clutch 30 is released. . When the lock-up relay valve 46 is switched to the state on the left side of the drawing, the line oil pressure P _L of the oil pressure source 2 is supplied to the engagement-side oil chamber 36 as the engagement oil pressure P _ON , and the line pressure in the release-side oil chamber 38 is adjusted. The hydraulic oil is caused to flow out to the lock-up control valve 48, and the lock-up clutch 30 is engaged. The lock-up control valve 48 turns on the differential pressure ΔP between the engagement oil pressure P _ON and the release oil pressure P _OFF when the lock-up clutch 30 is engaged,
By pressure regulating in response to the signal pressure P _S which is supplied from the OFF electromagnetic valve 50, the lock-up clutch 3
0 is completely engaged so as not to slip, or engaged in a predetermined slip state. The ON / OFF electromagnetic opening / closing valve 50 energizes and de-energizes the solenoid 54 at a predetermined duty ratio according to the ON / OFF signal supplied from the slip control electronic control device 52, and connects the hydraulic power source 1 and the lock-up control valve 48. The passage for communication and the passage for communication between the lock-up control valve 48 and the drain oil passage are opened and closed at the duty ratio, so that a constant modulator oil pressure P supplied from the oil pressure source 1 is supplied.
_The pressure of _M is adjusted according to the duty ratio and output as a signal oil pressure P _S. The hydraulic pressure control circuit 44 and the hydraulic actuator 32 constitute a clutch driving unit.
The lock-up clutch 30 is frictionally engaged using the differential pressure ΔP as a driving force.

Here, the ON / OFF solenoid on-off valve 50
Switches to the state on the right side of the figure when the ON and OFF signals are ON.
Is replaced by a lock-up control valve from the hydraulic pressure source 1.
The passage leading to 48 is opened and the lock-up
The troll valve 48 and the drain oil passage are shut off and the signal oil pressure
P_SWhile the ON and OFF signals are OFF
The state is switched to the state on the left side of the
When the passage to the control valve 48 is closed
The lock-up control valve 48 and the drain oil passage
Is communicated and the signal pressure P_SBecomes lower. Accordingly
When the ON time of the ON / OFF signal is long,
If the duty ratio is large, the signal oil pressure P _SIs high
Release hydraulic pressure P by the lock-up control valve 48.
_OFFIs reduced to increase the differential pressure ΔP,
The slip rotation speed Δω of the lock-up clutch 30
That is, the engine speed ω_EAnd the input shaft 20 (turbine blade
Rotation speed ω of car 22)_TAnd the rotational speed difference (ω_E−ω_T)
When the ON time is short while the
If the duty ratio is small, the signal oil pressure P_SIs lower,
Release hydraulic pressure P by the backup control valve 48_OFFBut
As the differential pressure ΔP becomes smaller due to
The slip rotation speed Δω of the up clutch 30 increases.
You. In addition, it opens with the ON and OFF of the ON and OFF signals.
Signal oil pressure P to close_SFurther, the differential pressure ΔP
2 ON, OFF as shown in the fourth and fifth stages
It fluctuates in the same cycle as the signal.

The slip control electronic control unit 52 includes a CP
U, ROM, RAM, a so-called microcomputer composed of an interface, etc.
By performing signal processing in accordance with a program previously stored in the ROM while utilizing the temporary storage function of M, the slip rotation speed detecting means 60 and the output timing control means 6
2. Duty ratio calculation means 64 and signal output means 6
6 are executed, and the ON,
Outputs an OFF signal. The slip control electronic control unit 52 is supplied with engine information SE such as engine speed ω _E , intake air amount, throttle valve opening, ignition timing, etc. from engine information detecting means such as various sensors provided in the engine 10. At the same time, transmission information ST such as input shaft rotation speed ω _T , shift speed, oil temperature and the like is supplied from transmission information detecting means such as various sensors provided in the automatic transmission 14.

The slip rotation speed detecting means 60 detects the slip rotation speed Δω (= ω _E −ω _T ), and can be obtained by an arithmetic expression from the torque of the engine 10, for example. That is, since the engine 10 generates torque due to the explosion, the engine torque is oscillatory, but assuming that the oscillation is sinusoidal, the engine torque _TE is given by the following equation (2). . Further, since the equation of motion for transmitting and receiving the torque of the engine 10 is given by the following equation (3), substituting this into the equation (2) and transforming it gives the following equation (4). _{T E = T E1 + T E2} × sin (k × n × θ) ··· (2) where, T _E1: the average value of the engine torque T _E T _E2: the variation amount of the engine torque (1/2 amplitude) k : 1 1 / 2,2 cycles at 4 cycles n: number cylinders theta: angle of rotation _{T C = T E -I E ×} Ω E ··· of the engine 10 (3) where, T _C: to the torque converter 12 Input torque (including input torque to lock-up clutch 30) _IE : Moment of inertia of engine 10 Ω _E : Angular acceleration of engine 10 Ω _E = [ _TE1 - _TC + _TE2 x sin (k x n x θ) )] / _IE ... (4)

Here, in order to prevent the torque fluctuation of the engine 10 from being transmitted to the automatic transmission 14 side, the input torque T _C needs to be constant, and the vehicle speed and the engine rotation speed must be constant. In a nearly constant equilibrium state ∫
Since Ω _E dθ = 0, eventually T _C = T _E1 ,
Equation (4) can be rewritten as the following equation (5). When the rotational angular acceleration Ω _E is integrated, the following equation (6) is obtained, while the target slip rotational speed of the lock-up clutch 30 is set to Δω ₀
Then, the following equation (7) is obtained, and the slip rotation speed Δω =
ω _E −ω _T can be expressed by the following equation (8) from the equations (6) and (7). Ω _E = (T _E2 / I _E ) × sin (k × n × θ) (5) ω _E = ∫Ω _E dθ = − (T _E2 / I _E / k / n) × cos (k × n × θ) + ω _E0 (6) where ω _{E0 is} an initial value of the engine rotation speed ω _E Δω ₀ = ω _E0 −ω _T (7) Δω = − (T _E2 / I _E / k / N) × cos (k × n × θ) + Δω ₀ (8)

The above I _E , k, n are predetermined according to the engine 10 and the target slip rotation speed Δω ₀
Is set to a constant value in advance, while the engine torque fluctuation _TE2 is obtained from a data map or the like using the throttle valve opening, intake air amount or ignition timing as parameters, and the rotation angle θ is the rotation angle. Since it can be detected by a sensor or the like, the slip rotation speed Δω can be calculated from equation (8) based on such information. If the engine rotation speed ω _E and the input shaft rotation speed ω _T are detected using a rotation speed sensor capable of detecting the rotation speed fluctuations due to the torque fluctuations of the engine 10 with high accuracy, the rotation speeds of the engine rotation speeds ω _E and The slip rotation speed Δω can be directly calculated from the speeds ω _E and ω _T, and the slip rotation speed Δω can be detected with higher accuracy by using the above equation (8).

The output timing control means 62 determines the slip rotation speed Δω based on the slip rotation speed Δω.
the pressure difference ΔP
The output timing at which the ON / OFF signal is output at the same frequency as the variation frequency of the slip rotation speed Δω is determined so as to vary. That is, in the region where the slip rotation speed Δω is small, for example, as shown in FIG.
Therefore, the transmission torque T _LU of the lock-up clutch 30 changes accordingly, while the differential pressure P fluctuates in the same cycle as the ON and OFF signals, and the transmission torque T _LU fluctuates accordingly. Therefore, if the ON and OFF signals are output so that the differential pressure ΔP fluctuates contrary to the fluctuation of the friction coefficient μ, the torque fluctuation caused by the fluctuation of the friction coefficient μ and O
The torque fluctuations caused by the N and OFF signals are canceled each other, and the fluctuations of the transmission torque T _LU caused by them are suppressed. In FIG. 3, since the friction coefficient μ decreases as the slip rotation speed Δω increases, as shown in FIG.
The output timing is set based on the change in the slip rotation speed Δω so that the N and OFF signals are output ON. Further, an output cycle and a duty ratio are required to determine the ON time of the ON / OFF signal, and the output timing is also determined by the output timing control means 62. Output period is the same as the fluctuation period of the slip speed [Delta] [omega, can also be measured by means of a engine rotational speed omega _E and the rotational angle theta. Since there is a predetermined delay time between the opening and closing of the ON / OFF solenoid on-off valve 50 and the change in the differential pressure ΔP, the output timing is set so that the ON / OFF signal is output earlier by the delay time. It is desirable.

The duty ratio calculating means 64 calculates the duty ratio D ₁ according to, for example, the following equation (9). DFWD _{1 in the} equation (9) is a feedforward value, which is a duty ratio at which a differential pressure ΔP that is a target transmission torque T _LU is obtained. This is in order to cut off the torque fluctuation of the engine 10 is required to be input torque T _C = T _E1 to the torque converter 12 including a lock-up clutch 30, but the input torque T _C is fluid transmission torque T _F And the transmission torque T _LU of the lock-up clutch 30.
When the slip rotation speed Δω is very small, T _F ≒ 0
Therefore, it suffices to set T _LU = T _E1 after all.
The engine torque average value T _E1 is obtained from the throttle valve opening, the intake air amount, the average engine speed ω _{Eav, and the} like. On the other hand, the transmission torque T _LU is represented by the above equation (1). Differential pressure Δ that provides a driving force F that satisfies
P may be obtained from the pressure receiving area of the piston 34 of the hydraulic actuator 32. The friction coefficient μ in the equation (1) is set to a constant value in advance based on the target slip rotation speed Δω ₀ , or the friction coefficient μ and the slip rotation speed Δω as shown in FIG. 3 using the average slip rotation speed Δω _av as a parameter. May be sequentially set from a data map, an arithmetic expression, or the like that represents the relationship with. Here, the fluctuation of the friction coefficient μ due to the periodic fluctuation of the slip rotation speed Δω may be ignored. The DFB in the equation (9) is a feedback correction value, which is a deviation ΔE (= Δω _av −Δ) between a predetermined target slip rotation speed Δω ₀ and an actual average slip rotation speed Δω _av.
ω ₀ ) is determined from a well-known feedback control equation or the like so as to eliminate ω ₀ ). Further, KGD is a learning value that is updated in response to individual differences between the engine 10 and the vehicle, changes over time, and the like. The average engine rotation speed ω _Eav and the average slip rotation speed Δω _av are calculated based on the engine rotation speed ω _E ,
The rotation period of the engine 10 can be determined by detecting the rotation period of the engine 10 based on the rotation angle θ, for example, based on the average value of one or a plurality of periods of the slip rotation speed Δω. D ₁ = DFWD ₁ + DFB + KGD (9)

The signal output means 66 multiplies the output period obtained by the output timing control means 62 by the duty ratio D ₁ obtained by the duty ratio calculation means 64 to obtain an ON time. ON, OF that turns ON for the ON time at the set output timing
Outputs F signal. The signal output means 66 and the duty ratio calculation means 64 make the duty control means 6
8, and the duty control means 68 and the output timing control means 62 constitute a friction-based driving force control means.

[0025] In such a slip control device of this embodiment, the duty ratio D ₁ to slip engagement is required to lock-up clutch 30 at the target slip rotational speed [Delta] [omega _0, ON at the duty ratio D _1, OFF signal Is output, the ON / OFF solenoid valve 50 is opened / closed according to the ON / OFF signal, and the differential pressure ΔP is adjusted. In this case, the differential pressure ΔP fluctuates with the opening / closing of the ON / OFF solenoid on-off valve 50, and the transmission torque T _LU also fluctuates according to the oil pressure fluctuation. Since the OFF signal is output at the same frequency as the slip rotation speed Δω, the OFF signal is output so that the differential pressure ΔP fluctuates contrary to the fluctuation of the friction coefficient μ accompanying the fluctuation of the slip rotation speed Δω. The transmission torque fluctuation caused by the oil pressure fluctuation caused by the opening and closing of the on-off valve 50 and the transmission torque fluctuation caused by the fluctuation of the friction coefficient μ cancel each other, and the fluctuation of the transmission torque T _LU is suppressed as a whole. FIG. 2 is a time chart at the time of such slip control. The left half has a long fluctuation period, that is, the engine rotation speed ω _E is slow, and the right half has a short fluctuation period, that is, the engine rotation speed ω _E. Is fast, and the ON and OFF signals are output at the same cycle as the fluctuation cycle.

As described above, in this embodiment, the fluctuation of the transmission torque T _LU due to the fluctuation of the friction coefficient μ caused by the fluctuation of the slip rotation speed Δω is suppressed. region slip speed [Delta] [omega is small coefficient μ is varied, with a lower limit a slip speed [Delta] [omega _X following regions in FIG. 3, for example, 50 rpm specifically
Coefficient of friction μ
The slip control is performed so that the torque fluctuation does not occur in the drive system such as the automatic transmission 14 due to the fluctuation of the torque. When the slip rotation speed Δω is reduced in this manner, power loss and heat generation are reduced, and fuel efficiency and the life of the clutch are improved. In this embodiment, ON, OF
Since the transmission torque fluctuation caused by the fluctuation of the friction coefficient μ is suppressed by utilizing the oil pressure fluctuation caused by the opening and closing of the F solenoid on-off valve 50, the transmission torque fluctuation caused by the oil pressure fluctuation is also suppressed at the same time. ON, OFF, inexpensive and easy to control
The accuracy of transmission torque control using the electromagnetic on-off valve 50 is improved.

Next, an embodiment of the first invention will be described. In the following embodiments, portions common to the first embodiment are denoted by the same reference numerals, and detailed description is omitted.

In FIG. 4, a hydraulic control circuit 70 constituting a clutch driving means together with the hydraulic actuator 32
Is provided with a linear solenoid valve 72 instead of the ON / OFF electromagnetic on-off valve 50. In the linear solenoid valve 72, when a drive current having a magnitude corresponding to the duty ratio is supplied from the slip control electronic control device 76 to the solenoid 74, a thrust corresponding to the drive current is applied to the spool valve element. , it generates a signal hydraulic pressure P _S which is proportional to the drive current. Electronic control unit 76 for slip control
Outputs a drive current at a predetermined duty ratio repeatedly at a predetermined cycle time sufficiently shorter than the torque fluctuation cycle of the engine 10. The friction coefficient calculation means 77 calculates, for example, the friction coefficient μ shown in FIG. From the relationship with the speed Δω, a friction coefficient μ corresponding to the actual slip rotation speed Δω is calculated. The friction coefficient calculation means 77 includes a relation storage means for storing the relation between the friction coefficient μ and the slip rotation speed Δω in the form of a data map, an arithmetic expression or the like. Duty ratio calculation unit 78, for example, calculates a duty ratio D ₂ according to the following equation (10), although feedforward value DFWD ₂ is obtained in the substantially same manner as DFWD _1, driving, thereby satisfying the expression (1) The force F is obtained by using the friction coefficient μ calculated by the friction coefficient calculation means 77. As a result, the friction coefficient μ accompanying the fluctuation of the slip rotation speed Δω
Irrespective of the variation of the transmission torque, the desired substantially constant transmission torque T _LU can be obtained. The feedback correction value DF
B and the learning value KGD are the same as in the above equation (9). D ₂ = DFWD ₂ + DFB + KGD (10)

The signal output means 80 outputs a drive current at the duty ratio D ₂ obtained by the duty ratio calculation means 78. The signal output means 80, the friction coefficient calculating means 77, and the duty ratio calculating means 78 constitute a frictional driving force control means 82.

In such a slip control device,
Since the friction coefficient μ is determined in accordance with the slip rotation speed Δω, and the duty ratio D ₂ for obtaining the target transmission torque T _LU is calculated using the friction coefficient μ, fluctuations in the slip rotation speed Δω Therefore, even if the friction coefficient μ fluctuates, a desired substantially constant transmission torque T _LU can be obtained. FIG. 5 is an example of a time chart of the engine torque T _E , the slip rotation speed Δω, the friction coefficient μ, the differential pressure ΔP (duty ratio D ₂ ), and the transmission torque T _LU , regardless of the fluctuation of the engine torque T _E. The transmission torque T _LU is maintained substantially constant.

As described above, also in the present embodiment, the transmission torque T _LU is prevented from fluctuating due to the fluctuation in the friction coefficient μ accompanying the fluctuation in the slip rotation speed Δω. region slip speed [Delta] [omega is small friction coefficient μ is varied, for example, in the following areas limit the slip rotation speed [Delta] [omega _X in FIG. 3, the torque fluctuation in the driving system such as an automatic transmission 14 due to the variation of the friction coefficient μ is Slip control is performed so as not to occur.
When the slip rotation speed Δω is reduced in this manner, power loss and heat generation are reduced, and fuel efficiency and the life of the clutch are improved.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above-described embodiment, the slip control of the lock-up clutch 30 provided in parallel with the torque converter 12 and transmitting the torque of the engine 10 has been described. However, the torque generated by another drive source is transmitted by the frictional force. The present invention can be similarly applied to other clutches. The hydraulic power transmission device such as the torque converter 12 is not always essential, and the type of the clutch is
As long as the friction coefficient μ changes in accordance with the slip rotation speed Δω, the present invention is not necessarily limited to the friction clutch provided with the friction plate, and the clutch driving means is appropriately changed according to the type of the clutch.

In the above-described embodiment, the lock-up relay valve 46 is switched by a control device different from the slip control electronic control devices 52 and 76. The lock-up relay valve 46 may be switched. The switching control of the shift speed of the automatic transmission 14 can also be performed by a common electronic control device.

Although the stepped automatic transmission 14 is provided in the above embodiment, a continuously variable transmission or a speed reducer that reduces the speed at a constant speed ratio may be provided. The present invention can be applied to a power transmission device without a transmission.

Although not specifically exemplified, the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vehicle power transmission device including a slip control device according to an embodiment of the present invention.

FIG. 2 is a time chart for explaining fluctuations in a friction coefficient μ, a transmission torque T _{LU and the} like when a lock-up clutch of the vehicle power transmission device of FIG. 1 is slip-controlled.

FIG. 3 is a diagram illustrating an example of a relationship between a slip rotation speed Δω of the lock-up clutch of FIG. 1 and a friction coefficient μ.

FIG. 4 is a configuration diagram of a vehicle power transmission device including a slip control device according to another embodiment of the present invention.

5 is a time chart for explaining fluctuations in a friction coefficient μ, a transmission torque T _{LU and the} like when a lock-up clutch of the vehicle power transmission device of FIG. 4 is slip-controlled.

[Explanation of symbols]

 10: Engine (power source) 30: Lock-up clutch 32: Hydraulic actuator 44: Hydraulic control circuit 50: ON / OFF solenoid on-off valve 60: Slip rotation speed detecting means 62: Output timing control means 68: Duty control means 70: Hydraulic pressure Control circuit 82: frictional driving force control means

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Claims (2)

(57) [Claims] 1. A clutch for transmitting a torque generated by a power source by frictional force, and a clutch driving means for engaging the clutch, wherein a driving force of the clutch driving means is controlled so as to slip-engage the clutch. A slip rotation speed detecting means for detecting a slip rotation speed of the clutch, wherein the slip rotation speed detection means detects a slip rotation speed of the clutch.
In order to prevent the transmission torque from fluctuating, the slip rotation speed is controlled in accordance with the slip rotation speed.
A clutch slip control device comprising: a friction-responsive driving force control unit that varies the driving force of the clutch driving unit in a manner opposite to the variation of the friction coefficient caused by the variation. 2. The clutch driving means includes a hydraulic actuator that engages the clutch using hydraulic pressure as a driving force, and an ON / OFF electromagnetic opening / closing valve that opens and closes according to ON / OFF signals to adjust the hydraulic pressure. A hydraulic control circuit, wherein the friction-responsive driving force control means includes: a duty control means for outputting the ON / OFF signal at a predetermined duty ratio for causing the clutch to slip-engage; 2. An output timing control means for outputting the ON / OFF signal at the same frequency as the fluctuation frequency of the slip rotation speed so that the driving force fluctuates contrary to the accompanying fluctuation of the friction coefficient. A slip control device for a clutch as described in the above.