Rotary expansible chamber devices – With mechanical sealing – Axially movable end wall or end wall portion
Reexamination Certificate
2002-03-13
2004-01-06
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
With mechanical sealing
Axially movable end wall or end wall portion
C196S139000
Reexamination Certificate
active
06672853
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to hydraulic systems, and more particularly to a hydraulic apparatus including a pressure clamped hydraulic pump.
BACKGROUND OF THE INVENTION
In a hydraulic apparatus including a motor driven pump, it is often desirable to make the component parts as small and highly integrated as possible, so that the apparatus will be compact, light weight, inexpensive to manufacture and maintain, and highly reliable. U.S. Pat. No. 6,152,715 describes a pressure clamped hydraulic pump that is held together by pressure produced in the pump, thereby allowing the elimination of bolts and other fasteners used to hold together pumps of a more conventional design.
Although prior pressure clamped pumps, such as the pump of the '715 patent, provide considerable reduction in size and complexity as compared to more conventional pump designs, further improvement is needed to resolve several problems related to using a pressure clamped pump in a hydraulic apparatus. These problems include difficulty in aligning the drive shaft of the pump with the output shaft of a drive motor, lack of provisions for positively retaining the drive shaft so that it cannot be inadvertently pulled out of the pump, and inherent restrictions on the size of the pump inlet resulting from the structure of prior pressure clamped pumps.
As shown in
FIGS. 1-4
, The pressure clamped pump
100
of the '715 patent includes a housing
102
having an external threaded portion
104
that engages threads
106
in a cavity
108
of a valve block
110
, and a pair of o-ring seals
112
,
114
that mate with surfaces of the cavity
108
to seal the inlet and outlet of the pump
100
, so that the pump
100
may be installed by simply screwing the pump
100
into the cavity
108
until the seals
112
,
114
seat against the surfaces of the cavity
108
.
As shown in
FIG. 1
, the pump
100
includes a drive shaft
116
extending from the upper end of the housing
102
. The housing
102
defines a central axis
118
and an outer diameter ‘A.’ The drive shaft
116
is offset from the central axis
118
by a distance ‘B.’ This offset ‘B’ creates several problems in aligning and connecting the drive shaft
116
of the pump
100
to the output shaft
120
of a motor
122
providing rotational force to the drive shaft
116
. As shown in
FIG. 3
, the center of the cavity
108
is coincident with the central axis
118
of the pump
100
, as the pump
100
is screwed into and seated in the cavity
108
. The offset ‘B’ of the drive shaft
116
from the central axis
118
results in the center of the drive shaft
116
orbiting in a circular path
124
, having a radius equal to the offset ‘B,’ about the center
118
of the cavity
108
, as the pump
100
is screwed into the cavity
108
.
Slight dimensional differences in the configurations of the pump
100
and cavity
108
, due to inherent manufacturing tolerances and variations in installation torques, result in the drive shaft
116
coming to rest at different positions along the circular path
124
, when the seals
112
,
114
are fully seated against the surfaces of the cavity
108
. Because the position of the drive shaft
116
varies along the circular path
124
, the motor
122
must be capable of mounting to the block
110
in any position wherein the drive shaft
116
might come to rest along the circular path
124
, so that the output shaft
120
of the motor
122
may be properly aligned to engage the drive shaft
116
of the pump
100
. This requires that the motor
122
be mounted to the block
110
with adjustable mounts, such as the pair of clamps
126
, so that the output shaft
120
of the motor
122
may follow the drive shaft around the circular path
124
at the radius ‘B.’
As a result, even though the motor
122
has a diameter ‘C,’ the block
110
must be large enough to accommodate a motor footprint
128
having a diameter ‘D’ equal to the diameter ‘C’ of the motor
122
plus twice the offset ‘B.’ To accommodate the mounting clamps
126
, the footprint may have to be even bigger, resulting in a valve block
110
having a minimum square or circular profile defining a dimension ‘E,’ as shown in
FIGS. 3 and 4
, that is much larger than the diameters of either the pump
100
or the motor
122
. Much of the advantage of small size provided by the pressure clamped pump
100
is thus lost due to the offset ‘B.’
The offset ‘B’ also creates other problems. There is no positive means of aligning the output shaft
120
of the motor
122
with the drive shaft
116
of the pump
100
. If these shafts are not properly aligned, the misalignment places high stresses on the shafts
120
,
116
which may cause the pump
100
and or motor
122
to fail prematurely. In addition, it is not possible to utilize provisions, such as the bolts
130
holding the motor
122
together, to also mount the motor
122
on the block
110
, thereby precluding further reduction in size and complexity of the hydraulic apparatus.
As shown in
FIG. 1
, a pump
100
according to the '715 patent utilizes a series of balls
132
for axially supporting the drive shaft
116
and an idler shaft
134
in the housing
102
. Because the drive shaft
116
extends out of the upper end of the housing
102
, the drive shaft
116
is supported only on its lower end by one of the balls
132
. The drive shaft
116
is keyed to a drive gear
136
of the pump
100
, and passes through a shaft seal
138
at the point of exit from the housing
102
. Because the drive shaft
116
is supported axially only at the lower end by the ball
132
, the drive shaft
116
of prior pressure clamped pumps may be inadvertently pulled out of the drive gear
136
and through the seal
138
, thereby rendering the pump inoperative. This may occur, for example, during removal of the drive motor
122
, if the motor output shaft
120
has become stuck together with the pump drive shaft
116
during operation, or if the motor
122
is not pulled straight off of the drive shaft
116
along the central axis
118
, such that the output shaft
120
becomes canted with respect to the pump drive shaft
116
in a manner that would cause the drive shaft
116
to become wedged together with the output shaft
120
due to the canting of the motor
122
.
The lower balls
132
also present an undesirable physical restriction upon the size, shape, and placement of the pump inlet
140
, and present difficulties in manufacturing and assembling the pump
100
.
SUMMARY OF THE INVENTION
My invention provides an improved hydraulic apparatus and pressure clamped pump that solves one or more of the problems described above through the use of pump having a housing adapted for installation into a cavity and a drive shaft coincident with the center of the housing. In some forms of my invention, the hydraulic apparatus includes piloting features for facilitating alignment of the pump drive shaft with the output shaft of a motor used to drive the pump. The pump may include elements for retaining the drive shaft within the pump, and may also include a larger and less restricted inlet than could be achieved in prior pressure clamped pumps.
In one form of my invention, a hydraulic apparatus includes a block having a cavity adapted for receiving a pressure clamped hydraulic pump. The pump has a central axis and a drive shaft extending along the central axis. The block further includes an inlet channel and an outlet channel, with the inlet channel being adapted for communicating with the cavity and an inlet of the pump, and the outlet channel adapted for communicating with the cavity and an outlet of the pump.
The pump of the hydraulic apparatus may include a housing defining a central axis, an inlet and an outlet. The pump may further include a plurality of pump components positioned in axially disposed relation to one another, and pumping means located in the housing for drawing fluid into the inlet at a first pressure and pumping the fluid from the outlet at a second pressure greater than the first pressure. The pu
Crowe Lawrence E.
Vrablik John J.
LandOfFree
Center driven pressure clamped hydraulic pump does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Center driven pressure clamped hydraulic pump, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Center driven pressure clamped hydraulic pump will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3195292