192 clutches and power-stop control – Clutches – Fluent material
Reexamination Certificate
2000-04-21
2002-01-29
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Fluent material
C192S1030FA, C464S027000
Reexamination Certificate
active
06341682
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a hydraulic power transmission joint for motor vehicles, for use in the distribution of a driving force to front and rear wheels, and more particularly to a hydraulic power transmission joint cutting off torque without any influence of rotational differences between the front and rear wheels.
2. Description of the Related Arts
Conventional hydraulic power transmission joints are known from e.g., U.S. Pat. Nos. 5,706,658 and 5,983,635. Such a hydraulic power transmission joint is used in a fashion as shown in
FIG. 1
for example.
FIG. 1
illustrates an example of a hydraulic power transmission joint being currently developed by the inventors of the present application.
Referring to
FIG. 1
, a propeller shaft
101
connecting directly with front wheels is coupled too a companion flange
102
to which is coupled the hydraulic power transmission joint generally designated as
122
. The hydraulic power transmission joint
122
comprises a housing shank
104
formed with a cam face
103
and fixedly inserted into the inner periphery of the companion flange
102
, and a housing
105
secured by welding to the housing shank
104
. The housing shank
104
is supported via a front bearing
106
by a differential gear case
107
. A main shaft
108
acting as an output shaft connects with a drive pinion gear
109
associated with a rear differential gear. A rotor
110
is fitted via splines to the main shaft
108
and is rotatably housed in the housing
105
. The rotor
110
is provided with a plurality of axially extending plunger chambers
111
which accomodate plungers.
112
reciprocatively under a pressing force of return springs
113
, with the plungers
112
being operated by the cam face
103
upon the relative rotations between the two shafts. The rotor
110
is formed with an intake/discharge hole
114
leading to the plunger chambers
111
. A rotary valive
115
is provided with a discharge port and an intake port (neither of which are shown) which are capable of communicating with the intake/discharge hole
114
. The rotary valve
115
has an orifice (not shown) for generating a flow resistance by flow of oil discharged by the displacement of the plungers
112
. The rotary valve
115
is further provided with a weight
116
for cutting off torque. A bearing retainer
117
is securely press fitted to the housing
105
and is positioned by a snap ring
118
. Needle bearings
119
and
120
are interposed between the bearing retainer
117
and the rotary valve
115
and between the bearing retainer
117
and the main shaft
108
, respectively. An accumulator piston
121
is further provided for absorbing thermal expansion and contraction of oil residing within the joint.
Such a hydraulic power transmission joint
122
is arranged as shown in FIG.
2
and generates torque hydraulically as a function of the rotational-speed differences between the front and rear wheels. More specifically, the hydraulic power transmission joint
122
is interposed between a front differential gear
123
and a rear differential gear
124
, with the propeller shaft
101
acting as a driving shaft being coupled to the hydraulic power transmission joint
122
. The front differential gear
123
is interposed between front driving wheels
125
and
126
. The rear differential gear
124
is interposed between rear driven wheels
127
and
128
.
In the event that tires having diameters have been mounted on the front driving wheels
125
and
126
and on the rear dirven wheels
127
and
128
, the rotational-speed difference of the hydraulic power transmission joint
122
may increase accordingly as the vehicle velocity rises, with the result that torque may increase and accumulate within the front and rear differential gears
123
and
124
, adding to the running resistance. In order to solve this problem, as illustrated in
FIG. 3
, there is proposed a valve which is provided within the hyrdraulic power transmission joint
122
and which has a weight
116
operating depending on the vehicle velocity (centrifugal force) for torque cutoff. More specifically, a rotary valve
115
is spline mounted within the housing
105
connecting directly with the propeller shaft
101
, so as to rotate jointly with the housing
105
. A weight
116
is provided within the rotary valve
115
. In response to the number of rotations (centrifugal force), the weight
116
rotates around its center of rotation in the center of rotation in the direction indicated by an arrow A, so as to open a high-pressure oil drain portion
130
for draining off the high-pressure oil within the plunger chambers. on the vehicle velocity (centrifugal force) for torque cutoff. More specifically, a rotary valve
115
is spline mounted within the housing
105
connecting directly with the propeller shaft
101
, so as to rotate jointly with the housing
105
. A weight
116
is provided within the rotary valve
115
. In response to the number of rotations (centrifugal force), the weight
116
rotates around its center of rotation in the direction indicated by an arrow A, so as to open a high-pressure oil drain portion
130
for draining off the high-pressure oil within the plunger chambers to cut off torque.
Due to such a vehicle velocity (centrifugal force), dependent torque is cutoff by the operation of the weight provided within the hydraulic power transmission joint. However, the weight may work early and cut off the torque even at a low vehicle velocity, e.g., upon the escape from any difficult situations. More specifically, when in stuck, only the front wheels acting as the driving wheel sand the propeller shaft rotate at a higher speed, with the rotary valve
115
connecting directly with the propeller shaft, whereupon the weight
116
may work to cut off the torque transmission to the rear wheel side, making an escape from sandy or muddy spots difficult.
SUMMARY OF THE INVENTION
According to the present invention there is provided a hydraulic power transmission joint capable of cutting off torque depending on the vehicle velocity without any influence of rotational differences between front and rear wheels.
The present invention is directed to a hydraulic power transmission joint disposed between a driving shaft and a driven shaft which are capable of relative rotations, for transmitting torque depending on rotational-speed differences between the two shafts. According to a first aspect of the present invention, such a hydraulic power transmission joint comprises
a housing coupled to the driving shaft and having a cam face formed on the inner side of the housing; a rotor coupled to the driven shaft and rotatably housed in the housing, the rotor including a plurality of axially extending plunger chambers; a plurality of plungers each accommodated reciprocatively under a pressing force of a return spring in each of the plurality of plunger chambers, the plurality of plungers being operated by the cam face upon relative rotations between the two shafts; an orifice causing oil discharged by a displacement of the plunger to create a flow resistance to impart a high pressure to the interior of the plunger chamber, the orifice allowing torque transmitted from the housing to the rotor to be generated by a reaction force of the plunger; a valve which when a predetermined number of rotations is reached, operates to cut off torque; and a coupling member for coupling the rotor connecting to the driven shaft and the valve together, the coupling member allowing rotations of the valve to be in synchronism with rotations of the driven shaft.
In this case, the valve may include a weight which when a predetermined number of rotations are reached, rotates around its center of rotation by a centrifugal force to drain off a high-pressure oil residing within the plunger chamber. Preferably, the housing connects with a driving shaft in the form of a propeller shaft extending from a front differential gear, and the rotor connects with an input shaft of a rear differenti
Kato Tadahiko
Kusukawa Hirotaka
Murata Shigeo
Nakamura Masaki
Shimada Kazuhisa
Fujiunivance Co.
Lorence Richard M.
LandOfFree
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