192 clutches and power-stop control – Clutches – Fluent material
Reexamination Certificate
2000-05-15
2002-09-24
Lorence, Richard M. (Department: 3681)
192 clutches and power-stop control
Clutches
Fluent material
C192S08200T, C192S1030FA, C464S027000
Reexamination Certificate
active
06454070
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a drain mechanism for a hydraulic power transmission joint for use in 4 wheel-drive mechanisms for motor vehicles, and more particularly to a drain mechanism for a hydraulic power transmission joint, serving both as a temperature-based 2 wheel-drive switching mechanism and a torque limiter mechanism.
2. Description of the Related Arts
Such a hydraulic power transmission joint for use in an automobile 4 wheel-drive mechanism is hitherto known from U.S. Pat. Nos. 5,706,658 and 5,983,635.
FIG. 1A
illustrates an exemplary drain mechanism for use with a hydraulic power transmission joint being currently developed by the present inventors on the basis of such U.S. Patents. A rotor is provided in the hydraulic power transmission joint for transmitting torque as a function of the rotational-speed difference between an input shaft and an output shaft, the rotor being provided with a valve block
101
that rotates jointly with the rotor. The rotor is linked to a main shaft coupled to rear wheels, for integral rotation with the main shaft. The valve block
101
is formed with an accommodation hole
102
that accommodates a drain plug
105
having a drain hole
104
through which hydraulic pressure from a high-pressure chamber
103
is discharged. Within the drain plug
105
there is slidably provided a drain pin
106
for opening and closing the drain hole
104
. A fixed pin
107
is fixedly inserted into the valve block
101
for restricting the displacement of the drain pin
106
. A low-pressure chamber
108
is formed in the accommodation hole
102
of the valve block
101
. Within the low-pressure chamber
108
is provided a thermo-switch
111
that is urged by return springs
109
and
110
to press the drain pin
106
so as to block the drain hole
104
. The thermo-switch
111
is provided with a head pin
112
that protrudes outward when a predetermined temperature is reached. In the status where the predetermined temperature is not reached for operation, the thermo-switch presses the drain pin
106
leftward with the aid of the return springs
109
and
110
as shown in
FIG. 1A
, to block the drain hole
104
. At that time, the head pin
112
of the thermo-switch
111
does not abut against the fixed pin
107
with a minute gap therebetween. When the predetermined temperature is reached, the head pin
112
of the thermo-switch
111
is extended leftward as shown in
FIG. 1B
to abut against the fixed pin
107
, with the resultant reaction force causing the thermo-switch
111
to retreat rightward against the biasing forces of the return springs
109
and
110
. When the thermo-switch
111
retreats rightward, the force pressing the drain pin
106
is cut off, to release the drain pin
106
which in turn is displaced rightward by a high pressure from the high-pressure chamber
103
to open the drain hole
104
. As a result of this, oil within the high-pressure chamber
103
flows through the drain hole
104
and via a drain chamber
114
into a drain passage
115
as indicated by the arrow.
That is, when the drain pin
106
retreats to open the drain hole
104
as shown in
FIG. 2B
from the status of
FIG. 2A
in which the drain hole
104
is blocked by the drain pin
106
, oil within the high-pressure chamber
103
flows through the drain hole
104
into the drain chamber
114
, and thence is drained through the drain passage
115
into the low-pressure chamber as indicated by the arrow. A further displacement of the drain pin
106
is prevented by the abutment of the bottom of a recessed portion
113
of the drain pin
106
against the fixed pin
107
as shown in FIG.
2
B.
FIG. 3
illustrates torque characteristics in which characteristic A is obtained when the temperature of oil is below a predetermined level prior to the operation of the drain pin
106
, with the acquisition of the torque &Dgr;T being proportional to the square of the rotational-speed difference. In contrast to this, characteristic B is a torque characteristic obtained after the predetermined temperature has been exceeded for the operation of the drain pin
106
, in which the torque &Dgr;T continues to increase accordingly as the rotational-speed difference &Dgr;N increase since the drain capability runs short due to the smaller diameter of the drain hole
104
.
However, in such a conventional drain mechanism for the hydraulic power transmission joint, the drain hole had a reduced diameter to form an orifice, which allows the hydraulic pressure to be set to a higher level but which is apt to induce a shortage of the drain capability even after the operation of the drain pin at the temperature exceeding the predetermined level, whereupon the torque still continues to increase with the increase of the rotational-speed difference. Furthermore, in case of the function as the torque limiter for keeping the torque at a predetermined level after the torque level has been reached, the torque also rose with the differential rotations due to the shortage of the drain capability.
SUMMARY OF THE INVENTION
The present invention provides a drain mechanism for a hydraulic power transmission joint, capable of alleviating insufficient drain capability and of keeping a certain torque when a predetermined torque is reached, as well as serving on the basis of the temperature as a 2 wheel-drive mechanism and a torque limiter.
The present invention is directed to a drain mechanism for a hydraulic power transmission joint adapted to be interposed between an input shaft and an output shaft that are rotatable relative to each other, to transmit torque as a function of the rotational-speed difference between the input and output shafts. According to a first aspect of the present invention, the drain mechanism comprises a limiter plug accommodated within a valve block and having a communication hole through which oil is introduced from a first high-pressure chamber; a thermo-switch located within a low-pressure chamber in the valve block in such a manner as to be urged by a return spring, the thermo-switch having a head pin that protrudes when a predetermined temperature is reached; a fixed pin fixedly inserted into the valve block, the fixed pin being positioned so as to allow the head pin of the thermo-switch urged by the return spring to abut thereagainst, the fixed pin when the head pin protrudes at the predetermined temperature causing the thermo-switch to retreat against the return spring; a limiter pin slidably located within the limiter plug, the limiter pin being pressed by the thermo-switch to close the communication hole for the duration in which the predetermined temperature is not reached, the limiter pin when the predetermined temperature is reached, opening the communication hole as a result of cutoff of the pressing force induced by a retreat of the thermo-switch, the limiter pin when a predetermined torque is reached, opening the communication hole by a high pressure from the first high-pressure chamber; a drain plug that follows the limiter plug, accommodated in the valve block, the drain plug having a drain hole through which oil is discharged from a second high-pressure chamber; and a drain pin slidably located within the drain plug in such a manner as to be urged by a drain spring, the drain pin having the first high-pressure chamber into which oil is introduced from the second high-pressure chamber and which opens to the communication hole, the drain pin closing the drain hole by means of a pressing force of the limiter pin until a predetermined temperature is reached, the drain pin rapidly opening the drain hole in response to a retreat of the limiter pin effected when the predetermined temperature is reached, the drain pin when a predetermined torque is reached for the duration in which the predetermined temperature is not yet reached, opening the drain hole while adjusting its balance so as to keep the predetermined torque.
Herein, the drain pin includes an orifice by way of which the first high-pressure chamber
Kato Tadahiko
Kusukawa Hirotaka
Murata Shigeo
Nakabayashi Akira
Nakano Hiroyuki
Fujiunivance Co.
Lorence Richard M.
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Drain mechanism for hydraulic power transmission joint does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Drain mechanism for hydraulic power transmission joint, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drain mechanism for hydraulic power transmission joint will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2819034