192 clutches and power-stop control – Clutches – Fluent material
Reexamination Certificate
2000-04-21
2001-07-10
Marmor, Charles A (Department: 3681)
192 clutches and power-stop control
Clutches
Fluent material
C464S027000
Reexamination Certificate
active
06257387
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a hydraulic power transmission joint for use in the distribution of a vehicle driving force and, more particularly, to a hydraulic power transmission joint rendering its unit lightweight and compact.
2. Description of the Related Arts
Conventional hydraulic power transmission joints are arranged, for example, between a propeller shaft associated with the front differential gear and the rear differential gear, to transmit a torque corresponding to the rotational-speed difference between the input and output shafts. Such hydraulic power transmission joints can include an oil pump type hydraulic transmission joint in which the rotation of a cam having recessed and raised portions thrust the plunger or the vane to displace oil. In the oil pump type hydraulic transmission joint, the oil must be discharged when the cam is in its descending stoke but sucked when it is in its ascending stroke. One way valves are therefore needed in order to prevent a reverse flow of oil from the high pressure chamber upon the intake as well as an oil leakage into the low pressure chamber upon the discharge.
One example of such a hydraulic power transmission joint equipped with one way valves is described in Japan Patent No. 98-164628.
FIG. 1
is a sectional view of the joint disclosed in Japan Patent No. 98-164628, and
FIGS. 2A and 2B
are explanatory diagrams of operations of
FIG. 1
joint. In
FIGS. 1
,
2
A and
2
B, a rotor
101
has a plurality of grooves formed in its outer peripheral portion. Each groove receives a vane
102
slidably inserted thereinto. To effect the function as a hydraulic pump, the relative rotations between a cam ring
103
and the rotor
101
cause a generation of hydraulic pressure within pump chambers
104
,
105
and
106
. The discharge ports of the pump chambers
104
,
105
and
106
are blocked so that the rotor
101
and cam ring
103
can rotate jointly like one rigid body by the hydrostatic pressure. Intake/discharge ports
111
,
112
and
113
serve as intake ports or discharge ports depending on the direction of rotations of the vanes
102
and communicate mutually with a first oil passage
114
. Similarly, intake/discharge ports
107
,
108
and
109
serve as intake ports or discharge ports by the action of the vanes
102
and communicate mutually with a second oil passage
110
. The intake/discharge ports
111
,
112
and
113
resulting in the intake ports or the discharge port at one time communicate with one another through the first oil passage
114
. The first oil passage
114
connects with the second oil passage
110
by way of check valves
120
and
121
acting as one way valves. When the vanes
102
relatively rotate counterclockwise as in
FIG. 2A
for example, the check valve
120
is closed to separate the high pressure side from the low pressure side while simultaneously the check valve
121
is opened allowing a communication with the high pressure side. As a result, the discharge ports of the pump chambers
104
,
105
and
105
are blocked to generate a hydrostatic pressure, the thus confined oil causing the rotor
101
and the cam ring
103
to rotate jointly like one rigid body, for torque transmission. On the contrary, when the vanes
102
relatively rotate clockwise, the check valve
121
is closed to separate the high pressure side from the low pressure side, while simultaneously the check valve
120
is opened to allow a communication with the high pressure side. In consequence, the discharge ports of the pump chambers
104
,
105
and
106
are blocked to generate a hydrostatic pressure, the thus confined oil causing the rotor
101
and the cam ring
103
to rotate jointly like one rigid body, for torque transmission. The first oil passage
114
and the second oil passage
110
open to an oil reservoir
115
by way of check valves
116
and
117
serving as one way valves permitting only the flow from the oil reservoir
115
. Such a hydraulic pressure circuit allows an action of discharge pressure proportional to the rotational speed at all times, irrespective of the direction of the relative rotations.
A cover
118
of
FIG. 1
includes a passage
119
for allowing an action of high pressure for thrusting up the vanes from annular recessed grooves provided in the rotor side surfaces, the passage
119
communicating with the intake/discharge ports
111
,
112
,
113
,
107
,
108
and
109
of
FIGS. 2A and 2B
. The discharged high pressure oil is allowed to circulate through orifices
122
and
123
communicating with each other of the first and second oil passages
114
and
110
. Check vales
120
and
121
are further incorporated for the constant action of high pressure on the bottoms of the vanes. The two check valves
120
and
121
serve to prevent any reverse flow of oil from the high pressure side through the intake passage as well as any oil leakage to the low pressure side through the discharge passage.
However, such a conventional hydraulic power transmission joint needs four one way valves which are incorporated in the both side cover portions making up the hydraulic chamber of the vane pump, with the result that a wider accommodation space is required and thus the cost itself also increases. Furthermore, the oil passage tends to become longer since the discharge ports and the intake ports of a plurality of hydraulic chambers are allowed to communicate with two check valves in common. In particular, an elongated intake path may bring about a defective intake due to the oil line resistance, and if the oil viscosity is high at the low temperature, the vanes or the plungers may fail to follow up, result in an occurrence of foreign noises.
Such a one way valve problem will apply similarly to the case of use of the one way valve in the hydraulic power transmission joint having a structure where the rotation of the cam thrusts the plungers in the axial direction to displace the oil, as in U.S. Pat. Nos. 5,706,658 and 5,983,635.
SUMMARY OF THE INVENTION
The present invention provides a hydraulic power transmission joint ensuring an increased degree of freedom in the arrangement of the plunger and achieving a lightweight and compact unit, as well as capable of preventing the occurrence of foreign noises due to a reduction of the oil intake resistance.
The present invention is directed to a hydraulic power transmission joint disposed between input and output shafts that are capable of relative rotations and adapted to transmit torque corresponding to a rotational-speed difference between the input and output shafts, the joint comprising a housing coupled to one of the input and output shafts and having a cam face formed on its inner side surface; a rotor coupled to the other of the input and output shafts and adapted to be rotatably accommodated in the housing, the rotor having a plurality of plunger chambers formed in the axial direction thereof; a plurality of plungers each being accommodated in each of the plurality of plunger chambers in a reciprocative manner under a biasing force of a return spring, the plungers being axially displaced by the cam face upon relative rotations of the input and output shafts; a discharge hole formed in the rotor and communicating with the plurality of plunger chambers; and a valve block having a high pressure chamber leading to the discharge hole, the valve block having an orifice adapted to generate a flow resistance by the flow of oil displaced by the action of the plungers.
The hydraulic power transmission joint having such a structure is characterized by the present invention in that it comprises a first one way valve for intake disposed in each of intake holes formed in the heads of the plurality of plungers, the first one way valve being adapted to open when each plunger is in its intake stroke but to close when it is in its discharge stroke; and a second one way valve for discharge disposed in each of discharge holes leading to the plurality of plunger chambers, the second one way valve
Hirao Kiyonori
Kato Tadahiko
Kusukawa Hirotaka
Murata Shigeo
Shimada Kazuhisa
Fujiunivance Co.
Marmor Charles A
Rodriguez Saul
Wenderoth , Lind & Ponack, L.L.P.
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