Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Plural rigidly related blade sets
Reexamination Certificate
2000-05-31
2002-02-05
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Plural rigidly related blade sets
C415S200000
Reexamination Certificate
active
06343913
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic turbomachine such as a pump, and in particular, the present invention relates to a diffuser provided in such a hydraulic turbomachine for defining a diffuser channel around an impeller of the turbomachine.
BACKGROUND OF THE INVENTION
FIG. 2
shows an example of a two-stage pump with a built-in motor, which is one variety of such a hydraulic turbomachine. This pump has a motor part
16
and a pump part
18
which have a rotating shaft
14
in common, and their respective housings
20
and
22
are joined adjacently to each other, with a separating wall
24
disposed between them.
The housing of the pump part
18
has an inlet port
26
and a discharge port
28
. There are disposed in the housing a first-stage impeller
34
and a second-stage impeller
36
securely connected to the rotating shaft
14
, and resin-made diffusers
40
and
42
provided around the first and second-stage impellers for defining diffuser channels around the impellers, respectively. Intermediate casings
46
and
48
are provided respectively around each set of the impeller and the corresponding diffuser in order to support the diffusers within the housing and to form first-stage and second-stage pumping chambers.
The diffuser
42
of the second-stage pumping chamber is cramped in an axial direction or a direction of extension of the shaft
14
between a cylindrical pressing member
52
extending the axial direction from the separating wall
24
and a radially extending wall
48
a
of the second-stage intermediate casing
48
, positioned on the upstream side thereof. Furthermore, the diffuser
40
of the first-stage pumping chamber is cramped between the wall
48
a
of the intermediate casing
48
and a radially extending wall
46
a
of the first-stage intermediate casing, positioned on the upstream side thereof.
Flanges
50
and
53
are formed along outer peripheral edges of the housings
20
and
22
of the motor part
16
and the pump part
18
which are positioned close to each other, and between the flanges
50
and
52
a
is cramped a flange
58
provided on the circumference of the separating wall
24
. Bolts
64
are passed through axially aligned holes formed in these flanges
50
,
53
, and
58
, and are fastened with nuts
68
.
This fastening of the bolts and the nuts securely fastens the housings
20
and
22
and, at the same time, the fastening force is transferred to the second-stage diffuser through the pressing member
52
of the separating wall
24
and, accordingly, the second-stage diffuser
42
, the second-stage intermediate casing
48
, the first-stage diffuser
40
, and the first-stage intermediate casing
46
are tightly fastened together between the pressing member
52
and a radially extending wall
20
a
of the housing
20
having the inlet port
26
.
However, in such a pump, since the fastening force imparted by the bolts and the nuts is directly applied to the diffusers, it is necessary for the diffusers to be formed of a resin material with sufficient hardness and high tenacity to withstand such a load. Alternatively, it is necessary for the diffusers to be formed thick in the axial direction. However, highly tenacious resin materials have poor moldability, and the production of a thick diffuser increases costs.
Moreover, since the diffuser and the intermediate casing are engaged with each other directly, it is required that the surfaces thereof engaged with each other be finely finished thereby raising costs.
The present invention takes the above into consideration and aims to provide a hydraulic turbomachine such as a pump which can use a thin diffuser molded from a resin material with relatively low tenacity.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, a hydraulic turbomachine comprises a housing, one or more impellers arranged rotatably around an axis within the housing, one or more resin-made diffusers provided around the above-noted one or more impellers, respectively, for defining diffuser channels around the impellers, one or more support members provided within the housing and pressed axially by corresponding ones of the diffusers for securely supporting them a direction of the above-noted axis within the housing, and elastic members held between surfaces of the support members and the diffusers the surface of which are, as noted above, axially pressed against each other.
Specifically, the above-noted support members may be intermediate casings disposed around each set of the impellers and the corresponding diffusers provided therearound to form pumping chambers within the housing.
Since, in the present invention, the diffuser and the support member or intermediate casing are not directly engaged with each other, and, instead, are engaged indirectly with each other with the elastic member being interposed therebetween, the fastening force axially imposed on the diffuser can be uniform across the engaging surface, whereby a resin material of the diffuser can have little tenacity as compared with that of the above-noted prior diffuser. Further, it is not necessary for the surfaces of the diffuser and the support member to be highly finished. Consequently, it is possible for the diffuser to be produced at low costs as compared with the above-stated prior art diffuser.
More specifically, the intermediate casing is provided with an O-ring receiving groove in a surface against which the diffuser is engaged in such a manner that the groove surrounds the axis around which the impeller rotates and an O-ring is placed in the groove as the elastic member.
REFERENCES:
patent: 354104007 (1979-08-01), None
Armstrong Westerman Hattori McLeland & Naughton LLP
Ebara Corporation
Look Edward K.
McAleenan James M
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