JP2003049874A - Control method for electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve control accuracy of engaging torque by correcting an effect of an air gap of electromagnetic clutches on a real time basis. SOLUTION: An air gap estimating means M6 estimates the air gap G on the basis of an actual magnetic flux density ϕs and an actual exciting current Is detected during control of the electromagnetic clutches CL and CR, and a target exciting current It calculated by a target exciting current calculating means M3 is corrected by using the air gap G. An actual engaging torque calculating means M7 calculates actual engaging torque Tsn on the basis of the air gap G and the actual magnetic flux density ϕs, and target engaging torque Ts outputted by a target engaging torque calculating means M1 is corrected by the actual engaging torque Tsn. By this, an aging effect of the air gap G of the electromagnetic clutches CL and CR is compensated on a real time basis and the control accuracy can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch control method for calculating a target exciting current from a target engaging torque of an electromagnetic clutch and performing feedback control so that the actual exciting current of the electromagnetic clutch matches the target exciting current. .

[0002]

2. Description of the Related Art A driving force distribution device having two clutches makes it possible to distribute the driving force of an engine to left and right driving wheels, to increase the driving force to be distributed to a turning outer wheel and to distribute it to a turning inner wheel. It is known that a force is reduced to generate a yaw moment in a turning direction to improve turning performance. In such a driving force distribution device, the above-mentioned 2
The present applicant has already proposed that each clutch is composed of an electromagnetic clutch (Japanese Patent Application No. 11-176651).
No.).

In the above-mentioned conventional electromagnetic clutch, the core and the armature having the coil housed therein are arranged on both sides in the axial direction of the friction engagement member, and the friction engagement member is arranged radially outside and inside the friction engagement member. An outer guide and an inner guide that slidably support the mating member are arranged, and a magnetic path closed by the core, the outer guide, the armature, and the inner guide is formed. The magnetic flux generated attracts the amateur to engage the friction engagement member.

By the way, in the above-mentioned prior art, the driving force distribution amount (that is, the engaging torque of the electromagnetic clutch) of the driving force distribution device obtained from the operating conditions of the vehicle such as the engine torque, the engine speed, the vehicle speed, and the steering angle is the target value. To match
A target exciting current of the electromagnetic clutch corresponding to the target engaging torque of the electromagnetic clutch is determined, and feedback control is performed so that the actual exciting current of the electromagnetic clutch matches the target exciting current.

However, when the friction engagement member of the electromagnetic clutch wears over time and the air gap of the magnetic circuit decreases, the magnetic flux density generated increases even if the exciting current of the electromagnetic clutch is the same. There was a problem that the fastening torque increased.

[0006] Therefore, the present applicant has filed Japanese Patent Application No. 2001-960.
In No. 61, the relation between the actual exciting current and the actual magnetic flux density when the electromagnetic clutch is not controlled is obtained, and the relation between the target magnetic flux density and the target exciting current is corrected based on the relation, so that the influence of the change in the air gap is reduced. Suggesting compensation.

[0007]

However, the one proposed in the above-mentioned Japanese Patent Application No. 2001-96061 has the influence of the change of the air gap based on the relationship between the actual exciting current and the actual magnetic flux density when the electromagnetic clutch is not controlled. However, there is a problem that the influence cannot be compensated in real time.

The present invention has been made in view of the above circumstances, and an object thereof is to correct the influence of the air gap of the electromagnetic clutch in real time to improve the control accuracy of the engagement torque.

[0009]

In order to achieve the above object, according to the invention described in claim 1, the target exciting current is calculated from the target engaging torque of the electromagnetic clutch, and the actual exciting current of the electromagnetic clutch is calculated as follows. In an electromagnetic clutch control method that performs feedback control so as to match the target exciting current, when the electromagnetic clutch is controlled, the actual engaging torque is calculated from the actual magnetic flux density and the actual exciting current, and the actual engaging torque matches the target engaging torque. There is proposed a method for controlling an electromagnetic clutch, which is characterized by performing feedback control as described above.

According to the above configuration, feedback control is performed so that the actual engagement torque calculated from the actual magnetic flux density and the actual excitation current during control of the electromagnetic clutch matches the target engagement torque, so the air gap of the electromagnetic clutch changes over time. The influence of the change can be compensated in real time, and the target engagement torque can be accurately generated in the electromagnetic clutch.

According to the invention described in claim 2,
In the electromagnetic clutch control method that calculates the target excitation current from the target engagement torque of the electromagnetic clutch and performs feedback control so that the actual excitation current of the electromagnetic clutch matches the target excitation current, the actual magnetic flux density and the A method for controlling an electromagnetic clutch is proposed which is characterized by correcting a target exciting current or a target engaging torque based on an actual exciting current.

According to the above configuration, the target exciting current or the target engaging torque is corrected on the basis of the actual magnetic flux density and the actual exciting current during the control of the electromagnetic clutch, so that the influence of the change with time of the air gap of the electromagnetic clutch is real time. It is possible to compensate and accurately generate the target engagement torque in the electromagnetic clutch.

According to the invention described in claim 3,
In the electromagnetic clutch control method that calculates the target exciting current from the target engaging torque of the electromagnetic clutch and performs feedback control so that the actual exciting current of the electromagnetic clutch matches the target exciting current, the actual magnetic flux density becomes A method for controlling an electromagnetic clutch is proposed which is characterized by correcting a target exciting current or a target engaging torque based on the above.

According to the above configuration, the target exciting current or the target engaging torque is corrected based on the actual magnetic flux density during the control of the electromagnetic clutch, so that the influence of the change over time of the air gap of the electromagnetic clutch is compensated for in real time. The target engagement torque can be accurately generated in the clutch.

According to the invention described in claim 4,
In the electromagnetic clutch control method that calculates the target exciting current from the target engaging torque of the electromagnetic clutch and performs the feedback control so that the actual exciting current of the electromagnetic clutch matches the target exciting current, when controlling the electromagnetic clutch, between the core and the armature. A method for controlling an electromagnetic clutch is proposed, which is characterized by correcting a target exciting current or a target engaging torque based on the air gap.

According to the above configuration, the target exciting current or the target engagement torque is corrected based on the air gap between the core and the armature during the control of the electromagnetic clutch, so that the influence of the change over time of the air gap of the electromagnetic clutch is real-time. Since the target engagement torque can be compensated for and the target engagement torque can be accurately generated in the electromagnetic clutch, and the magnetic flux density feedback control that requires a highly accurate magnetic flux density detection means is not performed, it can be realized at low cost.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

1 to 14 show a first embodiment of the present invention, FIG. 1 is a view showing the structure of a driving force distribution device, and FIG. 2 is a driving force at the time of turning to the right in a medium to low vehicle speed range. FIG. 3 is a diagram showing the action of the distribution device, FIG. 3 is a diagram showing the action of the driving force distribution device during a left turn in the middle and low vehicle speed range, and FIG.
5 is a sectional view taken along line 5-5 of FIG. 4, FIG. 6 is a sectional view taken along line 6-6 of FIG. 4, FIG. 7 is a perspective view of a sensor coil, FIG. 8 is a block diagram of magnetic flux density detecting means, and FIG. 9 is a sensor. 10 is a graph showing the relationship between the output voltage of the coil and the magnetic flux of the magnetic circuit, FIG. 10 is a block diagram of the control system, FIG. 11 is a map showing the relationship between the magnetic flux density and the exciting current for each air gap, and FIG. 12 is the air gap and the current. A map for retrieving the correction coefficient KGAP1 and the fastening torque correction coefficient KGAP2, FIG. 13 is a map for retrieving the actual fastening torque from the air gap and the actual magnetic flux density, and FIG. 14 is a conversion of the target fastening torque into the target exciting current in consideration of the air gap. It is a map to do.

The first embodiment is defined by claim 1 and claim 2.
It corresponds to the invention described in.

As shown in FIG . 1 , a transmission M is connected to the right end of an engine E, which is horizontally mounted on the front of a vehicle body of a front engine / front drive vehicle, and is driven at the rear of the engine E and the transmission M. A force distribution device T is arranged. Driving force distribution device T
The left front wheel WFL and the right front wheel WFR are connected to the left drive shaft AL and the right drive shaft AR, which extend from the left end and the right end of the left and right, respectively.

The driving force distribution device T includes a differential device D to which torque is transmitted from an external gear 3 that meshes with an input gear 2 provided on an input shaft 1 extending from a transmission M.
The differential device D comprises a double pinion type planetary gear mechanism, and a ring gear 4 formed integrally with the external gear 3.
And a planetary carrier 8 that supports a sun gear 5 coaxially arranged inside the ring gear 4, an outer planetary gear 6 that meshes with the ring gear 4, and an inner planetary gear 7 that meshes with the sun gear 5 in a state where they mesh with each other. Composed of. The differential device D is
While the ring gear 4 functions as an input element,
The sun gear 5 that functions as one output element is the left output shaft 9
The planetary carrier 8 that is connected to the left front wheel WFL via L and functions as the other output element is the right output shaft 9R.
Is connected to the right front wheel WFR via.

The carrier member 11 rotatably supported on the outer periphery of the left output shaft 9L is provided with four pinion shafts 12 arranged at 90 ° intervals in the circumferential direction, and the first pinion 13 and the second pinion shaft 12 are provided. The triple pinion member 16 in which the pinion 14 and the third pinion 15 are integrally formed is used for each pinion shaft 12
Each is rotatably supported by.

A first sun gear 17 which is rotatably supported on the outer periphery of the left output shaft 9L and meshes with the first pinion 13.
Is connected to the planetary carrier 8 of the differential device D.
Also, the second sun gear 18 fixed to the outer periphery of the left output shaft 9L
Engages with the second pinion 14. Furthermore, the left output shaft 9
A third sun gear 19 rotatably supported on the outer periphery of L meshes with the third pinion 15.

The numbers of teeth of the first pinion 13, the second pinion 14, the third pinion 15, the first sun gear 17, the second sun gear 18, and the third sun gear 19 in the embodiment are as follows.

Number of teeth of the first pinion 13 Zb = 17 Number of teeth of the second pinion 14 Zd = 17 Number of teeth of the third pinion 15 Zf = 34 Number of teeth of the first sun gear 17 Za = 32 Number of teeth of the second sun gear 18 Zc = 28 Number of teeth of third sun gear 19 Ze = 32 The third sun gear 19 can be coupled to the housing 20 via the left electromagnetic clutch CL, and the rotation speed of the carrier member 11 is increased by the engagement of the left electromagnetic clutch CL. To be done. The carrier member 11 can be coupled to the housing 20 via the right electromagnetic clutch CR, and the rotation speed of the carrier member 11 is reduced by the engagement of the right electromagnetic clutch CR. The right electromagnetic clutch CL and the left electromagnetic clutch CL
Is controlled by an electronic control unit U including a microcomputer.

The electronic control unit U has an engine torque T.
e, the engine speed Ne, the vehicle speed V, and the steering angle θ are calculated based on a predetermined program to control the left electromagnetic clutch CL and the right electromagnetic clutch CR.

However, when the vehicle makes a right turn in the medium and low vehicle speed range, the right electromagnetic clutch CR is engaged by a command from the electronic control unit U as shown in FIG.
Is coupled to the housing 20 and stopped. At this time, the left output shaft 9L integrated with the left front wheel WFL and the right output shaft 9R integrated with the right front wheel WFR (that is, the planetary carrier 8 of the differential device D) are the second sun gear 18, the second pinion 14,
Since they are connected via the first pinion 13 and the first sun gear 17, the rotation speed NL of the left front wheel WFL is equal to the right front wheel W.
The speed is increased in accordance with the following equation with respect to the rotational speed NR of FR.

NL / NR = (Zd / Zc) × (Za / Zb) = 1.143 (1) As described above, the rotation speed NL of the left front wheel WFL is relative to the rotation speed NR of the right front wheel WFR. When the speed is increased, the right front wheel W, which is the turning inner wheel, is indicated by the hatched arrow in FIG.
A part of the torque of FR can be transmitted to the left front wheel WFL which is the outer turning wheel.

The carrier member 11 is connected to the right electromagnetic clutch C.
Instead of stopping by R, if the engaging torque of the right electromagnetic clutch CR is adjusted appropriately to decelerate the rotation speed of the carrier member 11, the rotation speed NL of the left front wheel WFL is correspondingly reduced.
Is increased with respect to the rotation speed NR of the right front wheel WFR, and an arbitrary torque can be transmitted from the right front wheel WFR which is the turning inner wheel to the left front wheel WFL which is the turning outer wheel.

On the other hand, when the vehicle makes a left turn in the medium and low vehicle speed range, the left electromagnetic clutch CL is engaged by a command from the electronic control unit U, and the third pinion 15 operates the third sun gear 19 as shown in FIG. It is coupled to the housing 20 via the. As a result, the rotation speed of the carrier member 11 is increased with respect to the rotation speed of the left output shaft 9L, and the rotation speed N of the right front wheel WFR is increased.
The speed of R is increased according to the following equation with respect to the rotation speed NL of the left front wheel WFL.

NR / NL = {1- (Ze / Zf) × (Zb / Za)} ÷ {1- (Ze / Zf) × (Zd / Zc)} = 1.167 (2) As described above When the rotational speed NR of the right front wheel WFR is increased with respect to the rotational speed NL of the left front wheel WFL, the left front wheel W, which is the turning inner wheel, is indicated by the hatched arrow in FIG.
A part of the torque of FL can be transmitted to the right front wheel WFR, which is the turning outer wheel. Also in this case, the left electromagnetic clutch C
If the rotation speed of the carrier member 11 is increased by appropriately adjusting the engagement torque of L, the rotation speed NR of the right front wheel WFR is increased with respect to the rotation speed NL of the left front wheel WFL in accordance with the speed increase, and the vehicle turns. The front left wheel WFL, which is the inner wheel, turns to the front right wheel W, which is the outer wheel that turns.
Arbitrary torque can be transmitted to FR. Therefore, when the vehicle runs at low speed, it is possible to improve the turning performance by transmitting a larger torque to the turning outer wheel than to the turning inner wheel. It is possible to reduce the torque transmitted to the outer turning wheel during high-speed traveling as compared to during the medium-low speed traveling, or conversely, transmit torque from the outer turning wheel to the inner turning wheel to improve the traveling stability performance.

As is clear from the comparison of the equations (1) and (2), the first pinion 13, the second pinion 14, the third pinion 15, the first sun gear 17, and the second sun gear 18 are shown.
By setting the number of teeth of the third sun gear 19 as described above, the speed increase rate from the right front wheel WFR to the left front wheel WFL (about 1.143) and the speed increase rate from the left front wheel WFL to the right front wheel WFR (about 1 .167) can be made substantially equal.

Next, the structure of the left and right electromagnetic clutches CL and CR will be described with reference to FIGS. The left and right electromagnetic clutches CL and CR are connected to the left and right output shafts 9L and 9R by the axis L.
The structure of the left electromagnetic clutch CL will be described as a representative of the structure because it has a structure that is substantially bilaterally symmetric with respect to the plane of symmetry P orthogonal to the. The reference numeral of the component of the right electromagnetic clutch CR is the subscript "L" of the reference numeral of the component of the left electromagnetic clutch CL.
Is changed to "R".

The left electromagnetic clutch CL housed inside the housing 20 formed of a non-magnetic material such as aluminum alloy is
A core 21L formed of a magnetic material and having a substantially cylindrical shape is provided.
The core 21L is fixed to the inner peripheral surface of the housing 20 such that it cannot rotate and cannot move in the axial direction (left-right direction). The exciting coil 22L is housed inside the core 21L, and the right end surface of the exciting coil 22L is located on the right end surface. An armature 23L formed of a magnetic material in an annular shape so as to directly face each other is disposed so as to be movable left and right. A connector 36L for supplying power to the exciting coil 22L is provided in the housing 20. A sleeve 31 integral with the third sun gear 19 (see FIG. 1) is coaxially and relatively rotatably fitted on the outer periphery of the left output shaft 9L, and is transmitted to the inner peripheral surface of the armature 23L by a welding member W25. The cylindrical portion 25a of the
It is arranged between the outer peripheral surface of No. 1 and the inner peripheral surface of the core 21L so as to be movable in the axial direction.

The transmission member 25 is provided on the inner peripheral surface of the housing 20.
Pressure plate 25b formed integrally with L and 5
The clutch plates 27L ... And the stopper plate 28L are spline-fitted S1 so that they cannot rotate but can move in the axial direction. The left side surface of the pressure plate 25b of the transmission member 25L opposes the right side surface of the rightmost clutch plate 27L so that it can come into contact therewith. Further, the five clutch discs 33L ... Are spline-fitted S2 so as to be non-rotatable and axially movable on the outer peripheral surface of the guide portion 32L integrally provided at the left end of the sleeve 31. These five clutch disks 33L ... Are alternately stacked on the five clutch plates 27L ... And one stopper plate 28L.

As is apparent from FIG. 5, the five clutch discs 33L, which are spline-fitted to the outer peripheral surface of the guide portion 32L integral with the sleeve 31, are attached to both side surfaces thereof so as to be aligned in the circumferential direction. Provided with a large number of facings 33a. On the other hand, as is clear from FIG. 6, the five clutch plates 27L ... Spline-fitted to the inner peripheral surface of the housing 20 are made of metal plates without facing, and the facings 33a of the clutch discs 33L. Can be directly contacted with.

The right electromagnetic clutch CR has a symmetrical structure with the left electromagnetic clutch CL with the plane of symmetry P sandwiched therebetween, but the guide portion 32L of the left electromagnetic clutch CL is provided integrally with the sleeve 31 integral with the third sun gear 19. On the other hand, the guide portion 32R of the right electromagnetic clutch CR is different only in that it is provided integrally with the carrier member 11.

As is clear from FIGS. 4 and 7, a notch 21a is formed in the outer peripheral end surface of the core 21L facing the armature 23L, and a cylindrical sensor core protruding in the axis L direction inside the notch 21a. The sensor coil 35L is wound around 21b.

As shown in FIG. 8, the magnetic flux density detecting means 37L for detecting the magnetic flux density generated in the magnetic circuit composed of the core 21L and the armature 23L by exciting the exciting coil 22L is composed of a high frequency drive circuit 38L and an impedance detecting circuit. It is composed of a circuit 39L and the sensor coil 35L. The high frequency drive circuit 38L drives the sensor coil 35L, and the impedance detection circuit 39L detects the impedance of the sensor coil 35L to detect the impedance of the electronic control unit U.
Output to. When the magnetic flux density passing through the sensor coil 35L changes due to the excitation of the exciting coil 22L, the impedance of the sensor coil 35L changes. Therefore, the magnetic flux density can be known by detecting this impedance.

In this embodiment, the impedance is detected by using the eddy current. Eddy current is a current that circulates in a conductor when it is placed in a fluctuating magnetic field. If the sensor core 21b is made of a conductive material, an eddy current is generated in the sensor core 21b.
The impedance of the sensor coil 35L can be detected by utilizing this eddy current. That is, the high frequency drive circuit 3
When the sensor coil 35L is driven at a high frequency so that the magnetic flux in the sensor core 21b is not saturated at 8L, an eddy current is generated in the conductive sensor core 21b. Sensor core 21
In addition to impedance loss due to self-dielectric which is 90 ° out of phase with the drive wave,
Impedance loss occurs due to eddy currents that are 0 ° out of phase. The impedance loss due to the self-dielectric does not change if the frequency is constant because the magnetic flux in the sensor core 21b is not saturated. On the other hand, the impedance loss due to the eddy current fluctuates according to the magnetic flux density passing through the sensor coil 35L. Since the impedance obtained by combining the above two components shows a very large change with respect to the change in the magnetic flux density, the magnetic flux density can be known based on this impedance.

The reason why the impedance loss due to the eddy current changes according to the magnetic flux density is that the current amount of the eddy current actually changes depending on the magnetic permeability μ of the sensor core 21b. In general, in the case of a magnetic material, the magnetic permeability μ does not simply represent a constant but changes according to the magnetic flux density.

FIG. 9 shows the electromagnetic clutches CL and C of this embodiment.
Regarding R, the result of actually measuring the relationship between the output voltage of the sensor coil 35L and the magnetic flux of the magnetic circuit is shown. From this graph, it can be seen that the output voltage and the magnetic flux density have a substantially proportional relationship in a predetermined range of the output voltage of the sensor coil 35L.

As described above, since the magnetic flux density generated in the magnetic circuit formed by the core 21L and the armature 23L by the excitation of the exciting coil 22L changes according to the impedance of the sensor coil 35L, the magnetic flux is transmitted to the electronic control unit U. By storing the relationship between the density and the impedance in advance, the magnetic flux density can be detected based on the impedance detected by the impedance detection circuit 39L.

However, when power is supplied to the exciting coil 22L in order to engage the left electromagnetic clutch CL by a command from the electronic control unit U, as shown by the broken line in FIG.
A magnetic flux is formed along a closed magnetic path composed of 1 L and the amateur 23L, and the amateur 23L is excited by the exciting coil 22.
It is sucked toward L toward the left in the figure. Then, the transmission member 25L connected to the amateur 23L moves to the left,
The clutch plate 27L is provided between the pressure plate 25b provided on the transmission member 25L and the stopper plate 28L.
... and the clutch disc 33L are sandwiched. As a result, the clutch plate 27L that is spline-fitted S1 to the housing 20 and the clutch disc 33L that is spline-fitted S2 to the guide portion 32L are integrated, and the sleeve 31 that supports the guide portion 32L is attached to the housing 20.
Be combined with.

Similarly, the exciting coil 22R is engaged in order to engage the right electromagnetic clutch CR by a command from the electronic control unit U.
As shown by the broken line in FIG. 4, a magnetic flux is formed along the closed magnetic path composed of the magnetic material core 21R and the armature 23R, and the armature 23R is excited by the exciting coil 2
It is sucked to the right toward 2R. Then amateur 2
The transmission member 25R connected to the 3R moves to the right, and the clutch plate 27R is provided between the pressure plate 25b and the stopper plate 28R provided on the transmission member 25R.
And the clutch disks 33R ... Are sandwiched. As a result, the clutch plate 27R ... Spline-fitting S1 to the housing 20 and the clutch disc 33R ... Spline-fitting S2 to the guide portion 32R are integrated, and the carrier member 11 supporting the guide portion 32R is coupled to the housing 20. To be done.

Next, the control system of the left and right electromagnetic clutches CL and CR will be described.

As is apparent from FIG. 10, the electronic control unit U has the target engaging torque calculating means M1, the torque feedback controlling means M2, and the target exciting current calculating means M3.
, Current feedback control means M4, and drive circuit M5
An air gap estimating means M6 and an actual fastening torque calculating means M7.

First, the functions of the air gap estimating means M6 and the actual engagement torque calculating means M7, which are the features of this embodiment, will be described.

The air gap estimating means M6 is an electromagnetic clutch CL, C detected by the magnetic flux density detecting means 37L, 37R.
Based on the actual magnetic flux density φs of R and the actual exciting current Is of the electromagnetic clutches CL, CR detected by the current detecting means 40, 40, between the cores 21L, 21R of the electromagnetic clutches CL, CR and the amateurs 23L, 23R. Estimate the size of the air gap G.

The size of the air gap G is referred to the correlation map of the exciting current I and the magnetic flux density φ set for each size of the air gap G, and the actual exciting current Is during the control of the electromagnetic clutches CL and CR is referred to. And the actual magnetic flux density φs. That is, as shown in FIG. 11, the moving average (φav, Iav) of the detected values of the actual excitation current Is and the actual magnetic flux density φs of the past n times is calculated, and the air gap G is calculated.
Is an initial value of 0.5 mm, the current between the characteristic lines h1 and h2 is based on the φ-I characteristic line h1 and the φ-I characteristic line h2 when the air gap G has a wear limit value of 0.2 mm. Deviation of values, that is, h1 (φ) -h
The deviation of the current value between Iav and the characteristic line h2 with respect to 2 (φ), that is, RI which is the ratio of Iav−h2 (φ).
Calculate GAP0. Subsequently, the deviation RIGAP0 is compared with the already stored value RIGAP, and RIGAP0 <R
If it is IGAP, the counter is incremented and RIG
If AP0> RIGAP, the counter is decremented, this process is repeated a prescribed number of times, and if the absolute value of the counter is larger than the threshold value, the value of RIGAP is set to RIGAP.
Update to 0. RIGAP has an initial value of 1.0 and maintains the value after the system is turned off. Then, the air gap G is searched from the RIGAP with the map of FIG. 12 (A), the current correction coefficient KGAP1 is searched from the air gap G with the map of FIG. 12 (B), and the air gap G is searched from the map of FIG. 12 (C). The fastening torque correction coefficient KGAP2 is searched.

The actual engaging torque calculating means M7 is the actual exciting current Is detected by the current detecting means 40, 40, the air gap G estimated by the air gap estimating means M6, and the engaging torque correction coefficient KGAP2 (FIG. 12 (C)). (See FIG. 13), the actual engagement torque Tsn of the electromagnetic clutches CL and CR is calculated by Tsn = {g (φ) −Tz} × KGAP2 + Tz (3) (see FIG. 13). Here, g (φ) is a correlation function of φ-Tsn characteristics when the air gap G is in the initial state, and Tz is a corrected reference torque.

Returning to FIG. 10, the target engagement torque calculating means M
1 is a driving state of the vehicle, that is, engine torque Te, in order to distribute a predetermined torque to the left and right front wheels WFL, WFR.
The target engagement torque Tt of the electromagnetic clutches CL, CR is calculated based on the engine speed Ne, the vehicle speed V, the steering angle θ, and the like. The torque feedback control means M2 compares the actual engagement torque Tsn of the electromagnetic clutches CL and CR calculated by the actual engagement torque calculation means M7 with the target engagement torque Tt to match the actual engagement torque Tsn with the target engagement torque Tt. Outputs the fastening torque command value. The target exciting current calculating means M3 uses the engagement torque command value as the electromagnetic clutch CL,
The target exciting current It to be supplied to the exciting coils 22L and 22R of the CR is converted. At this time, the cores 21L and 21R and the amateur 23 estimated by the air gap estimating means M6
The correction is performed according to the change in the size of the air gap G between L and 23R.

The reason is that the air gap G is large in the initial state where the clutch plates 27L ..., 27R ... Of the electromagnetic clutches CL, CR and the clutch discs 33L ... 33R ... The air gap G gradually decreases with wear. Even if the same exciting current is applied to the exciting coils 22L and 22R, when the air gap G is large, the fastening torque is small and the torque transmission amount is small. When the air gap G is small, the fastening torque is large and the torque transmission amount is large. This is because the engagement torque of the electromagnetic clutches CL and CR fluctuates depending on the period of use due to the increase.

Therefore, the target exciting current calculating means M3 is
When converting the engagement torque command value output by the torque feedback control means M2 into the target excitation current It, as shown in FIG. 14, the air gap G estimated by the air gap estimation means M6 and the current correction coefficient KGAP1 (FIG. 12). (B)
See the following) and add the correction of the following formula.

It = {f1 (T) −f2 (T)} × KGAP1 + f2 (T) (4) where f1 (T) and f2 (T) are in the initial state where the air gap G is large, respectively. It is a correlation function of an exciting current and a fastening torque when the air gap G is at a wear limit.

The current feedback control means M4 has the target exciting current It calculated by the target exciting current calculating means M3,
The actual exciting current Is detected by the current detecting means 40, 40 is compared, and an exciting current command value for matching the actual exciting current Is with the target exciting current It is output to the drive circuit M5, and the drive circuit M5 causes the exciting current M5 to be detected. Excitation coil 22 based on the command value
Energize L and 22R.

As described above, even if the friction engagement members of the electromagnetic clutches CL and CR wear due to aging and the air gap G decreases, the electromagnetic clutches CL and CR that reflect the air gap G at each time in real time are reduced. Since the torque feedback control is performed using the actual engagement torque Tsn, not only the actual engagement torque Tsn of the electromagnetic clutches CL and CR can be precisely controlled to the target engagement torque Tt, but also the target air gap G is used to obtain the target. Since the exciting current It is corrected, the actual engagement torque Tsn can be controlled more precisely to the target engagement torque Tt.

Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment corresponds to the invention described in claim 3 together with the third embodiment described later.

As is apparent from a comparison of FIGS. 10 and 15, the torque feedback control means M is used in the second embodiment.
2. The air gap estimating means M6 and the actual engagement torque calculating means M7 are not provided, but the target exciting current correcting means M8 is provided instead. Target excitation current correction means M8
Is the correction current It by applying the actual magnetic flux density φs detected by the magnetic flux density detecting means 37L and 37R to the map shown in FIG.
-I is calculated, and the corrected exciting current I obtained by subtracting the correction current It-I from the target exciting current It output by the target exciting current calculating unit M3 is output to the current feedback control unit M4.

The map shown in FIG. 16 defines the relationship between the exciting current and the magnetic flux density for various air gaps G. First, the target exciting current calculating means is added to the characteristic line L1 corresponding to the air gap G in the initial state. The target exciting current It output by M3 is applied to search for the corresponding magnetic flux density φ. If the current air gap G matches the initial air gap G, the magnetic flux density detection means 37L, 3L.
The actual magnetic flux density φs detected at 7R should match the magnetic flux density φ on the characteristic line L1, but when the air gap G changes with time, the actual magnetic flux density φs does not match the magnetic flux density φ on the characteristic line L1. Therefore, the characteristic line L2 passing through the intersection of the target exciting current It and the actual magnetic flux density φs corresponds to the current air gap G, and the exciting current I retrieved from the magnetic flux density φ on the characteristic line L2 is transferred to the electromagnetic clutch CL, If it is supplied to CR, the electromagnetic clutch C
It is possible to match the engagement torques of L and CR with the target engagement torque Tt.

As described above, according to the second embodiment, the actual magnetic flux density φ obtained by detecting the target exciting current It output by the target exciting current calculating means M3 by the magnetic flux density detecting means 37L, 37R.
Since the correction is performed in real time by using s, the actual engagement torque of the electromagnetic clutches CL and CR can be precisely controlled to the target engagement torque Tt by compensating the influence of the change in the air gap G.

Next, a third embodiment of the present invention will be described with reference to FIGS. The third embodiment corresponds to the invention described in claim 3 together with the above-described second embodiment.

In the third embodiment, the target exciting current correcting means M8 is used.
The function (see FIG. 15) is different from that of the second embodiment. That is, the target exciting current correcting means M8 calculates the actual magnetic flux density φs detected by the magnetic flux density detecting means 37L and 37R as shown in FIG.
The correction current It-I is calculated by applying the correction current It-I to the map shown in FIG. 2 and the corrected excitation current I obtained by subtracting the correction current It-I from the target excitation current It output by the target excitation current calculation means M3.
To the current feedback control means M4.

The map shown in FIG. 17 defines the relationship between the exciting current and the magnetic flux density. If the air gap G is in the initial state, the target exciting current calculating means M3 outputs the target exciting current It. At this time, the magnetic flux density φ corresponding to the target engagement torque Tt should be generated, but the actual magnetic flux density that is actually detected when the air gap G changes over time becomes φs. Therefore, if the difference It-I of the exciting currents corresponding to the difference φ-φs between the two magnetic flux densities is subtracted from the target exciting current It as the correction current, the corrected exciting current I is output to the current feedback control means M4 and the electromagnetic feedback is performed. Clutch CL,
The magnetic flux density φ (that is, the target engagement torque Tt) can be generated in CR.

As described above, according to the third embodiment, the actual magnetic flux density φ obtained by detecting the target exciting current It output by the target exciting current calculating means M3 by the magnetic flux density detecting means 37L, 37R.
Since the correction is performed in real time by using s, the actual engagement torque of the electromagnetic clutches CL and CR can be precisely controlled to the target engagement torque Tt by compensating the influence of the change in the air gap G.

Next, a fourth embodiment of the present invention will be described with reference to FIGS. The fourth embodiment corresponds to the invention described in claim 4.

As shown with parentheses in FIG. 15, in the fourth embodiment, the air gap detecting means 41 is used instead of the actual magnetic flux density φs detected by the magnetic flux density detecting means 37L, 37R.
The air gap G detected by L and 41R is input to the target exciting current correcting means M8. Target excitation current correction means M8
Applies the air gap G detected by the air gap detecting means 41L, 41R to the map shown in FIG. 18 to calculate a correction current It-I, and corrects the target excitation current It output from the target excitation current calculating means M3. The corrected exciting current I obtained by subtracting the current It-I is used as the current feedback control means M.
Output to 4. The air gap detecting means 41L, 41
As R, for example, those described in JP 2001-41704 A can be used.

The map shown in FIG. 18 defines the relationship between the fastening torque and the exciting current for each size of the air gap G, and the characteristic line corresponding to the air gap G detected by the air gap detecting means 41L, 41R. (For example, L1)
Is selected and the target engaging torque Tt is applied to this characteristic line to search for the exciting current I, and the target exciting current It
The correction current It-I is subtracted from this to perform the correction. As a result, the corrected exciting current I can be output to the current feedback control means M4 to compensate for the influence of the air gap G, and the engagement torques of the electromagnetic clutches CL and CR can be made to match the target engagement torque Tt.

As described above, according to the fourth embodiment, the target exciting current It output by the target exciting current calculating means M3 is corrected in real time using the air gap G detected by the air gap detecting means 41L, 41R. Therefore, the electromagnetic clutches CL, CR are compensated for by the influence of the change in the air gap G.
The actual engagement torque of the electromagnetic clutches CL and CR can be precisely controlled to the target engagement torque Tt, and the magnetic flux density feedback control that requires expensive magnetic flux density detection means need not be performed. can do.

Although the embodiments of the present invention have been described in detail above, the present invention can be modified in various ways without departing from the scope of the invention.

For example, in the second to fourth embodiments, the target exciting current It is corrected based on the actual magnetic flux density φs or the air gap G, but the target fastening current is corrected based on the actual magnetic flux density φs or the air gap G. Even if the torque Tt is corrected, the same effect can be achieved.

Further, in the embodiment, the electromagnetic clutches CL and CR of the driving force distribution device for distributing the torque between the left and right driving wheels have been exemplified, but the present invention can be applied to electromagnetic clutches for other arbitrary uses.

[0073]

As described above, according to the invention described in claim 1, feedback is performed so that the actual engagement torque calculated from the actual magnetic flux density and the actual excitation current during control of the electromagnetic clutch matches the target engagement torque. Since the control is performed, it is possible to compensate for the influence of the change over time of the air gap of the electromagnetic clutch in real time and accurately generate the target engagement torque in the electromagnetic clutch.

According to the invention described in claim 2,
Since the target exciting current or target engaging torque is corrected based on the actual magnetic flux density and actual exciting current when controlling the electromagnetic clutch, the effect of changes over time in the air gap of the electromagnetic clutch is compensated in real time, and the target is accurately targeted to the electromagnetic clutch. Fastening torque can be generated.

According to the invention described in claim 3,
Since the target excitation current or target engagement torque is corrected based on the actual magnetic flux density during electromagnetic clutch control, the effect of changes over time in the air gap of the electromagnetic clutch is compensated in real time, and the target engagement torque is accurately generated in the electromagnetic clutch. Can be made.

According to the invention described in claim 4,
Since the target exciting current or the target engagement torque is corrected based on the air gap between the core and the armature when controlling the electromagnetic clutch, the effect of the change over time of the air gap of the electromagnetic clutch is compensated in real time to accurately target the electromagnetic clutch. Since the fastening torque can be generated and the magnetic flux density feedback control that requires highly accurate magnetic flux density detection means is not performed, it can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a driving force distribution device.

FIG. 2 is a diagram showing an operation of a driving force distribution device at the time of turning right in a medium and low vehicle speed range.

FIG. 3 is a diagram showing an operation of a driving force distribution device at the time of turning left in a medium and low vehicle speed range.

FIG. 4 is an enlarged view of a main part of FIG.

5 is a sectional view taken along line 5-5 of FIG.

6 is a sectional view taken along line 6-6 of FIG.

FIG. 7 is a perspective view of a sensor coil.

FIG. 8 is a block diagram of magnetic flux density detection means.

FIG. 9 is a graph showing the relationship between the output voltage of the sensor coil and the magnetic flux of the magnetic circuit.

FIG. 10 is a map showing the relationship between magnetic flux density and exciting current for each air gap.

FIG. 11 is a map showing the relationship between the exciting current and the magnetic flux density for each air gap.

FIG. 12 is a map for searching an air gap, a current correction coefficient KGAP1 and a fastening torque correction coefficient KGAP2.

FIG. 13 is a map for searching the actual fastening torque from the air gap and the actual magnetic flux density.

FIG. 14 is a map for converting a target engagement torque into a target exciting current in consideration of an air gap.

FIG. 15 is a block diagram of a control system according to second to fourth embodiments of the present invention.

FIG. 16 is a map for searching a corrected exciting current from the actual magnetic flux density according to the second embodiment of the present invention.

FIG. 17 is a map corresponding to FIG. 16 according to the third embodiment of the present invention.

FIG. 18 is a map for searching a corrected exciting current from an air gap according to the fourth embodiment of the present invention.

[Explanation of symbols]

21L core 21R core 23L amateur 23R amateur CL electromagnetic clutch CR electromagnetic clutch G air gap Is actual excitation current It Target excitation current Tsn Actual tightening torque Tt Target tightening torque φs actual magnetic flux density φt Target magnetic flux density

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuhiro Tomari             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory (72) Inventor Masakatsu Hori             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory (72) Inventor Koji Matsubara             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory (72) Inventor Kiyoshi Wakamatsu             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory (72) Inventor Shinichi Inagawa             1-4-1 Chuo Stock Market, Wako City, Saitama Prefecture             Inside Honda Research Laboratory F-term (reference) 3J057 AA01 BB04 GA34 GB02 GB19                       GB21 GB36 GB37

Claims (4)

[Claims] 1. A target exciting current (It) is calculated from a target engaging torque (Tt) of an electromagnetic clutch (CL, CR), and an actual exciting current (Is) of the electromagnetic clutch (CL, CR) is calculated as a target exciting current (It). In the control method of the electromagnetic clutch that performs feedback control so as to match with (1), the actual engagement torque (Tsn) is calculated from the actual magnetic flux density (φs) and the actual excitation current (Is) when controlling the electromagnetic clutch (CL, CR). Then, the feedback control is performed so that the actual engagement torque (Tsn) matches the target engagement torque (Tt). 2. The target exciting current (It) is calculated from the target engaging torque (Tt) of the electromagnetic clutch (CL, CR), and the actual exciting current (Is) of the electromagnetic clutch (CL, CR) is calculated as the target exciting current (It). In a control method of an electromagnetic clutch that performs feedback control so that the target excitation current (It) is based on the actual magnetic flux density (φs) and the actual excitation current (Is) during the control of the electromagnetic clutch (CL, CR). Alternatively, an electromagnetic clutch control method characterized by correcting a target engagement torque (Tt). 3. The target exciting current (It) is calculated from the target engaging torque (Tt) of the electromagnetic clutch (CL, CR), and the actual exciting current (Is) of the electromagnetic clutch (CL, CR) is calculated as the target exciting current (It). In the control method of the electromagnetic clutch that performs feedback control so as to match with (1), the target excitation current (It) or the target engagement torque (Tt) is controlled based on the actual magnetic flux density (φs) during the control of the electromagnetic clutch (CL, CR). A method for controlling an electromagnetic clutch, which comprises: 4. The target exciting current (It) is calculated from the target engaging torque (Tt) of the electromagnetic clutch (CL, CR), and the actual exciting current (Is) of the electromagnetic clutch (CL, CR) is calculated as the target exciting current (It). In a control method of an electromagnetic clutch that performs feedback control so that the core (21,
L, 21R) and the amateur (23L, 23R) based air gap (G), the target exciting current (It) or the target engagement torque (Tt) is corrected.