192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2002-07-02
2003-12-30
Rodriguez, Saul (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S03000R, C192S084930
Reexamination Certificate
active
06668996
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electromagnetic clutch which is connected by attracting an armature to a core excited by an exciting coil, and particularly to an electromagnetic clutch in which the connecting force can be controlled.
2. Description of the Related Art
Conventionally, there has been known a technique of providing a driving force distributing device having two clutches in an activating device, distributing the driving force of an engine to left and right driving wheels via the driving force distributing device, and increasing the driving force distributed to a gyratory outer wheel while decreasing the driving force distributed to the gyratory inner wheel, thereby generating a yaw moment in the gyrating direction and improving the gyration performance. A technique in which these two clutches are made up of electromagnetic clutches is disclosed in the Japanese Publication of Unexamined Patent Application No.H4-312217.
The electromagnetic clutch has a clutch core
201
, an exciting coil
202
, and an armature
203
, as shown in
FIG. 1. A
pressure plate
204
is provided with its one major surface facing a major surface of the clutch core
201
which is opposite to its aperture side. From the pressure plate
204
, a transfer member
205
is extended along the lateral side of the clutch core
201
. The transfer member
205
is welded to the armature
202
.
In this electromagnetic clutch, a magnetic flux density sensor is provided in order to detect the connecting force and perform feed-back control of the duty of a current supplied to the coil. The magnetic flux density sensor detects, by using a Hall element, the leakage flux quantity of a magnetic circuit including the clutch core
201
and the armature
203
, and estimates the magnetic flux density of the magnetic circuit from the leakage flux quantity, thus controlling the current flowing through the exciting coil.
However, when connecting the above-described electromagnetic clutch C, the armature
203
might be inclined with respect to the major surface of the clutch core
201
instead of being parallel to the major surface thereof and might be attracted to the clutch core
201
in this state, because of the wear of the clutch disc and depending on how closely the armature
203
and the transfer member
205
fit each other. When the armature
203
is inclined with respect to the major surface of the clutch core
201
and is attracted to the clutch core
201
in this state, the magnetic flux density sensor cannot accurately measure the attracting force of the armature
203
to the clutch core
201
.
When the armature
203
is inclined with respect to the major surface of the clutch core
201
and is attracted to the clutch core
201
in this state, the attracting force of the armature
203
to the clutch core
201
is erroneously measured and the connecting force of the electromagnetic clutch C cannot be accurately controlled.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electromagnetic clutch in which the attracting force of an armature to a core can be accurately controlled even when the core and the armature are not parallel to each other.
An electromagnetic clutch according to one embodiment of the present invention comprises: a core made of a magnetic material; an exciting coil for exciting the core; an armature arranged at a position facing one major surface of the core and adapted for being attracted to the core by a predetermined connecting force in accordance with a current supplied to the exciting coil; a plurality of magnetic flux measuring means, each having magnetically sensitive means and adapted for measuring the magnetic flux quantity of a magnetic circuit including the core and the armature; and control means for controlling the current flowing through the exciting coil in accordance with the result of the measurement by each of the magnetic flux measuring means and setting a predetermined connecting force as the connecting force of the armature to the core; each of the magnetically sensitive means being provided in the circumferential direction so that the magnetic flux density of the magnetic circuit is controlled in accordance with an output signal from each magnetically sensitive means.
In the electromagnetic clutch according to the present invention, a plurality of magnetic flux measuring means, each having magnetically sensitive means and adapted for measuring the magnetic flux quantity of a magnetic circuit including the core and the armature, are provided in the circumferential direction. Therefore, in the electromagnetic clutch according to the present invention, the magnetic flux quantity can be measured at a plurality of positions in the magnetic circuit.
An electromagnetic clutch according to another embodiment of the present invention comprises: a core made of a magnetic material; an exciting coil for exciting the core; an armature arranged at a position facing one major surface of the core and adapted for being attracted to the core by a predetermined connecting force in accordance with a current supplied to the exciting coil; magnetic flux measuring means having magnetically sensitive means and adapted for measuring the magnetic flux quantity of a magnetic circuit including the core and the armature; and control means for controlling the current flowing through the exciting coil in accordance with the result of the measurement by the magnetic flux measuring means and setting a predetermined connecting force as the connecting force of the armature to the core; the magnetically sensitive means being provided on the entire circumference in the circumferential direction of the core.
In the electromagnetic clutch according to the present invention, magnetic flux measuring means having magnetically sensitive means and adapted for measuring the magnetic flux quantity of a magnetic circuit including the core and the armature is provided on the entire circumference in the circumferential direction of the core. Therefore, in the electromagnetic clutch according to the present invention, the magnetic flux quantity of the magnetic circuit can be measured on the entire circumference in the circumferential direction of the core.
An electromagnetic clutch according to still another embodiment of the present invention comprises: a core made of a magnetic material; an exciting coil for exciting the core; an armature arranged at a position facing one major surface of the core and adapted for being attracted to the core by a predetermined connecting force in accordance with a current supplied to the exciting coil; current detecting means for detecting the current flowing through the exciting coil; a plurality of gap detecting means, each having position detecting means and adapted for detecting the distance between the core and the armature; and control means for correcting the relation between the attracting force between the armature and the core and the current flowing through the exciting coil in accordance with the result of the detection by the current detecting means and the result of the detection by each of the gap detecting means, and thus controlling the current flowing through the exciting coil; each of the position detecting means being provided in the circumferential direction of the core or the armature so that the current supplied to the exciting coil is determined in accordance with an output signal from each position detecting means.
In the electromagnetic clutch according to the present invention, a plurality of gap detecting means, each having position detecting means and adapted for detecting the distance between the core and the armature, are provided in the circumferential direction. Therefore, in the electromagnetic clutch according to the present invention, the distance between the core and the armature can be measured at a plurality of positions.
An electromagnetic clutch according to yet another embodiment of the present invention comprises: a core made of a magnetic material; an excitin
Inagawa Shinichi
Iwazaki Akihiro
Kusumi Masaaki
Matsubara Koji
Nekado Yasuo
Haverstock & Owens LLP
Rodriguez Saul
Sony Precision Technology Inc.
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