192 clutches and power-stop control – Clutches – Automatic
Reexamination Certificate
2001-12-21
2004-05-04
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Automatic
C180S381000, C180S382000, C192S084700, C192S11000B, C192S115000
Reexamination Certificate
active
06729455
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a support structure and a method for supporting an electromagnetic coupling between propeller shafts of a four-wheeled drive vehicle.
Japanese Patent Provisional Publication No. 10-213164 discloses a coupling (i.e. a drive power delivery unit)
501
, which is exemplarily shown in FIG.
1
.
The coupling
501
is located in a drive power delivery system for rear wheels of the four-wheeled drive vehicle for controlling coupling or uncoupling states of the rear wheels with respect to an engine and controlling the magnitude of drive power to be delivered to the rear wheels.
The coupling
501
is comprised of a rotational case
503
, an inner shaft
505
, a main clutch
507
of the multi-plate type, a pressure plate
509
, an armature
511
, an intermediate cam member
513
, a first cam
515
, a second cam
517
, a spring
519
, and an electromagnet
521
and a controller (not shown).
The rotational case
503
and the inner shaft
505
are located in a concentric fashion for rotational movement relative to one another, with the inner shaft
505
being disposed inside the rotational case
503
.
The rotational case
503
is coupled to a propeller shaft
523
remaining closer to a transfer unit (not shown). Also, the inner shaft
505
is coupled to a propeller shaft
525
, remaining closer to a rear differential unit, through a spline connection and is coupled through the propeller shaft
525
to the rear differential unit (which serves to distribute the drive power of the engine to left and right rear wheels).
The pressure plate
509
and the armature
511
are coupled to an inner circumferential periphery of the rotational case
503
through spline connections, respectively.
Further, the intermediate cam member
513
is located between the pressure plate
509
and the armature
511
for rotational movement relative to one another.
The first cam
515
is interposed between the armature
511
and the intermediate cam member
513
and is constructed of cam recesses
527
formed at an outer circumferential periphery of the intermediate cam member
513
, and rollers
529
engaging the respective cam recesses
527
.
The cam recesses
527
are equidistantly formed on the outer periphery of the intermediate cam member
513
in a circumferential direction, with each recess being shaped in a slanted profile with respect to an axial direction. Also, the rollers
529
are supported with the armature
511
for rotational movement.
The second cam
517
is of a ball cam, which is interposed between the pressure plate
509
and the intermediate cam member
513
.
The spring
519
is disposed between the armature
511
and the intermediate cam member
513
to urge the intermediate cam member
513
toward the cam
517
to absorb looseness for thereby improving a response of the cam
517
.
Further, in an event that an excitation of the electromagnet
521
is interrupted, the spring
519
serves to restore the armature
511
to its neutral position in a rotational direction to allow the intermediate cam member
513
to be restored to a neutral position in an axial direction, thereby precluding an needless torque from being produced.
Connected to the rotational case
503
is a rotor
531
which forms a magnetic flux path and which is formed with an axially extending annular cavity
535
in which a core
533
of the electromagnet
521
is received with a suitable amount of air gap.
Further, interposed between an outer circumferential periphery of the core
533
and the rotor
531
is a seal
537
, with another seal
539
being disposed between an inner circumferential periphery of the core
533
and the inner shaft
505
. The seals
537
,
539
serve to preclude oil from leaking from the rotational case
503
while preventing entry of water or dusts from outside.
The rotor
531
is formed with axially facing contact surfaces
541
to be brought into contact with the armature
511
, with an air gap
543
being formed between the armature
511
and the contact surfaces
541
.
The controller serves to control the excitation of the electromagnet
521
, an exciting current and an interruption of the excitation of the electromagnet
521
.
Upon excitation of the electromagnet
521
, a magnetic flux flow loop
545
is created in a magnetic flux path involving the air gap
543
, thereby attracting the armature
511
.
Upon attraction of the armature
511
, the rollers
529
are moved to urge the cam recesses
527
of the intermediate cam member
513
to actuate the first cam
515
by which the intermediate cam member
513
is rotated.
Upon rotation of the intermediate cam member
513
, the second cam
517
is actuated to produce a cam thrust force by which the main clutch
507
is urged via the pressure plate
515
and is brought into a coupled condition.
In such a manner, when the electromagnet
521
attracts the armature
511
, its pilot function allows the first cam
515
to be operated to actuate the second cam
517
such that the coupling
501
is coupled.
When the coupling
501
is coupled, the drive power of the engine is delivered to the rear wheels to allow the vehicle to be brought into the four-wheeled drive condition, thereby improving a covering property of a rough road and a running stability in a vehicle body.
Further, when the exciting current of the electromagnet
521
is controlled, the cam force of the first cam
515
varies to vary the urging force exerted by the second cam
517
, permitting the main clutch
507
to slip for thereby adjusting the drive force to be delivered to the rear wheels. Thus, controlling a drive power distribution ratio between the front and rear wheels allows driveability and operating stability of the vehicle to be improved during a circular traveling of the same.
Upon termination of excitation of the electromagnet
521
, the urging force of the spring
519
allows the armature
511
(i.e. the rollers
529
) to be restored to the original position such that the cam force of the first cam
515
is lost. When this occurs, the cam thrust force of the second cam
517
also disappears to release the main clutch
507
for thereby uncoupling the coupling
501
such that the vehicle is brought into a two-wheeled drive condition.
The coupling
501
is interposed between the propeller shaft
523
,
525
in states exposed to the atmosphere.
In an event where the coupling
501
is located between the propeller shafts
523
,
525
, there are some instances where, owing to upward or downward movements of the wheels during traveling of the vehicle or the rear wheels riding on stepped portions or convex positions of the rough road during an off-road running condition, the thrust forces are directly imparted to the coupling
501
through the propeller shafts
523
,
525
, adversely affecting a gap between the outer plates and the inner plates of the main clutch
507
to variably change the air gap
543
between the rotor
531
and the armature
511
with a resultant degraded operating performance and degraded durability caused in the coupling
501
.
Also, the presence of the coupling
501
exposed to the outside increases possibilities for the coupling
501
to conflict with obstacles such as flying stones during traveling or to conflict with the stepped portions or the convex portions of the rough road.
As a consequence, the rotational case
503
must have a strength to resist such collisions, with a resultant increase in thickness to have an increased diameter as well as increase in weight.
Also, since the rotational case
503
must have an adequate strength, a difficulty is encountered in the rotational case
503
to be formed with aluminum alloy to reduce the weight.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a support structure for an electromagnetic coupling which is located on propeller shafts and which is enabled to protect the electromagnetic coupling from conflicting with obstacles, from entry of the obstacles and from being subjected to a thrust force exerted from the prop
Hirota Isao
Ubagai Toshikazu
Bonck Rodney H.
Morrison & Foerster / LLP
Tochigi Fuji Sangyo Kabushiki Kaisha
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