U.S. patent application number 15/024425 was filed with the patent office on 2016-08-11 for positive displacement gear pump.
This patent application is currently assigned to Gianpiero Pansolini. The applicant listed for this patent is Gianpiero Pansolini, Franco TOMMASINI. Invention is credited to Franco Tommasini.
Application Number | 20160230760 15/024425 |
Document ID | / |
Family ID | 49817191 |
Filed Date | 2016-08-11 |
United States Patent
Application |
20160230760 |
Kind Code |
A1 |
Tommasini; Franco |
August 11, 2016 |
POSITIVE DISPLACEMENT GEAR PUMP
Abstract
A positive displacement pump (1) comprises a casing with a
central body (2) and two closing lids (20), said central body (2)
being provided with two cylindrical communicating chambers (22,
23), one suction pipe (I) and one discharge pipe (O), and two
rotors (3, 4) revolvingly mounted in said chambers (22, 23) of the
central body and supported by shafts (5, 6) revolvingly mounted in
said closing lids (20). The two rotors comprise: a male rotor (3)
comprising only protuberances (30), not cavities, and a female
rotor (4) comprising only cavities (40), not teeth or
protuberances.
Inventors: |
Tommasini; Franco; (Ashmara,
ER) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOMMASINI; Franco
Pansolini; Gianpiero |
Asmara
Terni (TR) |
|
ER
IT |
|
|
Assignee: |
Pansolini; Gianpiero
Terni (TR)
IT
|
Family ID: |
49817191 |
Appl. No.: |
15/024425 |
Filed: |
September 27, 2013 |
PCT Filed: |
September 27, 2013 |
PCT NO: |
PCT/IT2013/000260 |
371 Date: |
March 24, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 18/08 20130101;
F04C 29/02 20130101; F04C 15/0026 20130101; F04C 2/20 20130101;
F01C 1/123 20130101; F04C 15/0088 20130101; F04C 18/123 20130101;
F04C 27/006 20130101; F04C 2/123 20130101; F04C 2/08 20130101 |
International
Class: |
F04C 18/08 20060101
F04C018/08; F04C 2/08 20060101 F04C002/08 |
Claims
1. A positive displacement pump comprising: a casing comprising a
central body and two closing lids, said central body being provided
with two communicating cylindrical chambers, one suction pipe and
one discharge pipe, and two rotors revolvingly mounted in said
chambers of the central body and supported by corresponding shafts
revolvingly mounted in said closing lids, characterized in that
said two rotors comprise: a male rotor having an outer surface that
comprises protuberances said outer surface being substantially free
of cavities, and a female rotor having an outer surface that
comprises cavities said outer surface being substantially free of
protuberances and teeth, wherein the protuberances of the male
rotor are engaged in the cavities of the female rotor without
contact between the two rotors.
2. The pump of claim 1, wherein said male rotor comprises a
cylindrical body and a plurality of protuberances that protrude
radially from the cylindrical body and said female rotor comprises
a cylindrical body and a plurality of cavities that extend radially
inside the cylindrical body.
3. The pump of claim 2, wherein each protuberance of the male rotor
cross-sectionally comprises two involute-shaped sides converging
into a rounded head, the two sides of each protuberance being
symmetrical with respect to a radial axis of symmetry passing
through the head of the protuberance, and each cavity
cross-sectionally comprises two involute-shaped sides joined into a
bottom surface with concave shape, wherein the profiles of the two
sides of the cavity are asymmetrical with respect to a radial
straight line passing through the bottom of the cavity, the
involute-shaped profile of the inlet side having a higher curvature
than the involute-shaped profile of the outlet side of the
cavity.
4. The pump of claim 3, wherein the male and female rotors are
centered in the chambers of the central body in such manner to
leave a tolerance space of between 0.05 mm, and 0.02 mm, between
the following parts: between the heads of the protuberances of the
male rotor and the internal surface of the cylindrical chamber of
the central body, between the heads of the protuberances of the
male rotor and the bottom surface of the cavities of the female
rotor, between the external surface of the cylindrical body of the
female rotor and the internal surface of the cylindrical chamber of
the central body of the casing, between the external surface of the
cylindrical body of the female rotor and the external surface of
the cylindrical body of the male rotor.
5. The pump of claim 1, wherein the male rotor comprises two
diametrally opposite protuberances and the female rotor comprises
two diametrally opposite cavities.
6. The pump of claim 1, wherein the protuberances of the male rotor
are provided with heads and the head diameter of the male rotor is
identical to the diameter of the cylindrical body of the female
rotor.
7. The pump of claim 2, wherein the diameter of the cylindrical
body of the male rotor is identical to the diameter of the
cylindrical body of the female rotor.
8. The pump (1) of claim 1, wherein the male rotor comprises a
cylindrical body provided with seats and said protuberances consist
in sectors comprising a base that is engaged in the seat of the
cylindrical body of the rotor.
9. The pump of claim 1, further comprising two external gears
comprising toothed wheels keyed onto the shafts of the rotors
outside said casing.
10. The pump of claim 1, also further comprising: two plate-shaped
seal gaskets disposed between said central body and said lids and a
plurality of springs disposed between said lids and seal gaskets in
such manner to stress the seal gaskets against the planar sides of
the rotors.
11. The pump of claim 10, wherein said seal gaskets and said rotors
are coated with an anti-friction self-lubricating material.
12. The pump of claim 3, wherein the male rotor comprises two
diametrally opposite protuberances and the female rotor comprises
two diametrally opposite cavities.
13. The pump of claim 3, wherein the protuberances of the male
rotor are provided with heads and the head diameter of the male
rotor is identical to the diameter of the cylindrical body of the
female rotor.
14. The pump of claim 3, wherein the diameter of the cylindrical
body of the male rotor is identical to the diameter of the
cylindrical body of the female rotor.
15. The pump of claim 3, wherein the male rotor comprises a
cylindrical body provided with seats and said protuberances consist
in sectors comprising a base that is engaged in the seat of the
cylindrical body of the rotor.
16. The pump of claim 3, further comprising: two plate-shaped seal
gaskets disposed between said central body and said lids; and a
plurality of springs disposed between said lids and seal gaskets in
such manner to stress the seal gaskets against the planar sides of
the rotors.
17. The pump of claim 16, wherein said seal gaskets and said rotors
are coated with an anti-friction self-lubricating material.
18. The pump of claim 6, wherein the male rotor comprises a
cylindrical body provided with seats and said protuberances consist
in sectors comprising a base that is engaged in the seat of the
cylindrical body of the rotor.
19. The pump of claim 6, further comprising: two plate-shaped seal
gaskets disposed between said central body and said lids; and a
plurality of springs disposed between said lids and seal gaskets in
such manner to stress the seal gaskets against the planar sides of
the rotors.
20. The pump of claim 19, wherein said seal gaskets and said rotors
are coated with an anti-friction self-lubricating material.
Description
[0001] The present patent application for industrial invention
relates to a positive displacement gear pump.
[0002] Various types of positive displacement pumps with internal
gears are known on the market, being used to transport liquid or
gaseous fluids from a suction pipe to a discharge pipe of the
pump.
[0003] FIG. 1 shows a positive displacement gear pump according to
the prior art, generally indicated with reference numeral (101).
The pump (101) comprises a casing (102) with suction pipe (I) and
discharge pipe (0). Two identical rotors (103) are mounted inside
the casing (102). Each rotor (103) comprises a gear composed of a
toothed wheel. Each rotor comprises a plurality of linear or
helicoidal teeth (130) that define a plurality of cavities (131)
between said teeth (130).
[0004] The two gears (103) are engaged in such manner that the
teeth (130) of one gear are engaged into the cavities (131) of the
other gear, and vice versa. So the fluid enters the suction pipe
(I) and comes out of the discharge pipe (O).
[0005] This type of positive displacement pumps of the prior art is
impaired by drawbacks caused by fluid encapsulation. As a matter of
fact, the fluid treated by the pump is trapped in the cavities of
the rotor and compressed by the teeth of the other rotor, thus
generating micro-explosions. Said micro-explosions considerably
reduce the number of rotor revolutions, causing a considerable wear
of the rotors and generating failure points in the rotor
toothing.
[0006] Vane pumps are additionally known, comprising a rotor
provided with cavity in which vanes slide radially. The rotor is
mounted eccentrically with respect to the seat of the casing where
it is housed and the vanes are stressed by springs or by the
centrifugal force towards the surface of the rotor housing.
[0007] Said vane pumps permit a limited number of revolutions,
cause early wear of vanes and require oil lubrication and
consequently a separator to separate oil from the fluid treated by
the pump.
[0008] The purpose of the present invention is to overcome the
drawbacks of the prior art, by disclosing a positive displacement
gear pump capable of avoiding fluid encapsulation.
[0009] Another purpose of the present invention is to obtain such a
positive displacement gear pump that is able to operate with a high
number of revolutions and is extremely reliable and safe.
[0010] These purposes are achieved according to the invention with
the characteristics claimed in the attached independent claim
1.
[0011] Advantageous embodiments appear from the dependent
claims.
[0012] The positive displacement pump of the invention
comprises:
[0013] a casing that comprises a central body and two closing lids,
said central body being provided with two communicating cylindrical
chambers, one suction pipe and one discharge pipe, and
[0014] two rotors revolvingly mounted in said chambers of the
central body and supported by corresponding shafts revolvingly
mounted and supported in said closing lids.
[0015] The two rotors comprise:
[0016] a male rotor that only comprises protuberances, not
cavities, and
[0017] a female rotor that only comprises cavities, not
protuberances or teeth.
[0018] The male rotor is engaged with the female rotor, i.e. the
protuberances of the male rotor are engaged in the cavities of the
female rotor without contact between the two rotors.
[0019] The provision of male rotor and female rotor avoids fluid
encapsulation in the cavities of the female rotor. Consequently,
the pump of the invention can be used at a high number of
revolutions, with minimum stress for mechanical moving parts.
[0020] Additional characteristics of the invention will appear
evident from the detailed description below, with reference to the
attached drawings, which have an illustrative, not limitative
purpose only, wherein:
[0021] FIG. 1 is cross-sectional view of a positive displacement
gear pump according to the prior art;
[0022] FIG. 2 is an exploded perspective view of the positive
displacement gear pump according to the invention;
[0023] FIG. 3 is a cross-sectional view of the pump of FIG. 2 in
assembled condition;
[0024] FIG. 4 is an exploded view of a male rotor of the pump shown
in FIG. 2; and
[0025] FIG. 5 is an exploded perspective view of an additional
embodiment of the pump shown in FIG. 2.
[0026] Referring now to FIGS. 2, 3 and 4, a positive displacement
pump according to the invention is disclosed, generally indicated
with reference numeral (1).
[0027] The pump (1) comprises a casing provided with central body
(2) sealed by means of two plate-shaped closing lids (20).
[0028] The central body (2) comprises two communicating cylindrical
chambers (22; 23) in such manner to form a basically 8-shaped
opening that is closed by the two lids (20). The central body is
provided with two pipes (I, O) in communication with outside,
respectively to suck and discharge the fluid treated by the
pump.
[0029] A male rotor (3) and a female rotor (4) are disposed in the
cylindrical chambers (22, 23) of the central body. The male rotor
(3) comprises only protuberances (30), not cavities. Instead, the
female rotor (4) comprises only cavities (40), not teeth or
protuberances. The male rotor (3) is engaged with the female rotor,
i.e. the protuberances (30) of the male rotor are engaged in the
cavities (40) of the female rotor without contact between the two
rotors. The male and female rotors (3, 4) are mounted on
corresponding shafts (5, 6). The shafts (5, 6) of the rotors are
revolvingly supported on supports (bushes or bearings, not shown in
the figures) provided in the seats (24) of the lids (20).
[0030] Preferably, the shaft (6) of the female rotor is connected
to a drive shaft. Therefore, the female rotor (4) is the driving
gear and the male rotor (3) is the driven gear. However, also the
shaft (5) of the male rotor can be connected to a drive shaft.
Moreover, both shafts (6, 5) of the rotors can be simultaneously
connected to two drive shafts in such manner to obtain better
torque distribution.
[0031] According to the rotation direction of the drive shaft, the
pipes (I, O) of the central body can act as suction pipe or
discharge pipe.
[0032] Advantageously, two external gears (7, 8) are disposed
outside the casing and keyed to the shafts (5, 6) of the rotors.
The external gears (7, 8) are engaging toothed wheels. The external
gears allow for phasing the male and female rotors (3, 4), meaning
that during the rotation of the two rotors, the protuberances (30)
of the male rotor enter the cavities (40) of the female rotor.
[0033] As shown in FIG. 3, the male rotor (3) comprises a
cylindrical body (35) and a plurality of protuberances (30)
radially protruding from the cylindrical body (35). Each
protuberance (30) cross-sectionally comprises two involute-shaped
sides (31, 32) converging into a rounded head (33). The two sides
(31, 32) of a protuberance are symmetrical with respect to a radial
axis of symmetry passing through the head (32) of the
protuberance.
[0034] Advantageously, the male rotor (3) comprises two
protuberances (30) in diametrally opposite positions. In such a
case, the chamber (22) of the central body of the casing defines a
suction area (A) in communication with the suction pipe (I) and a
discharge area (B) in communication with the discharge pipe
(O).
[0035] The female rotor (4) comprises a cylindrical body (45)
wherein a plurality of radially extending cavities (40) is
obtained. Each cavity (40) cross-sectionally comprises two
involute-shaped sides (41, 42) joined into a bottom surface (43)
with concave shape. The profiles of the two sides (41, 42) of the
cavity are not symmetrical with respect to a radial straight line
passing through the bottom of the cavity. The involute-shaped
profile of the inlet side (41) has a higher curvature than the
involute-shaped profile of the outlet side (42) of the cavity.
[0036] Advantageously, the female rotor (4) comprises two cavities
(40) in diametrally opposite positions.
[0037] The heads (33) of the protuberances of the male rotor are
very close to the internal surface of the cylindrical chamber (22).
During operation, the heads (33) of the protuberances of the male
rotor arrive at a short distance from the bottom (43) of the
cavity, thus avoiding the passage of liquid. However, the heads
(32) do not touch the internal surface of the cylindrical chamber
(22) or the bottom (43) of the cavity.
[0038] Moreover, the external surface of the cylindrical body (45)
of the female rotor is almost tangent to the internal surface of
the cylindrical chamber (23) of the central body of the casing, in
such manner to avoid the passage of liquid.
[0039] Similarly, the external surface of the cylindrical body (45)
of the female rotor is almost tangent to the external surface of
the cylindrical body (35) of the male rotor.
[0040] The male rotor (3) and female rotor (4) are perfectly
centered in the corresponding cylindrical chambers (22, 23) in such
manner to leave a tolerance space of 0.05 mm, preferably 0.02 mm,
between the following parts:
[0041] between the heads (33) of the protuberances of the male
rotor and the internal surface of the cylindrical chamber (22) of
the central body,
[0042] between the heads (33) of the protuberances of the male
rotor and the bottom surface (43) of the cavities of the female
rotor,
[0043] between the external surface of the cylindrical body (45) of
the female rotor and the internal surface of the cylindrical
chamber (23) of the central body of the casing,
[0044] between the external surface of the cylindrical body (45) of
the female rotor and the external surface of the cylindrical body
(35) of the male rotor.
[0045] FIG. 3 shows an additional embodiment, wherein the head
diameter (meaning the distance between the heads (33) of two
diametrally opposite protuberances) of the male rotor (3) is
identical to the diameter of the cylindrical body (4) of the female
rotor, in such manner to obtain two chambers (22, 23) with
identical diameter and make synchronization of the two rotors
easier. However, when the diameter of the cylindrical body (35) of
the male rotor (3) is smaller than the diameter of the cylindrical
body (45) of the female rotor (4), a minimum tolerance must be
provided between the two cylindrical bodies (35, 45) because the
peripheral speeds of the two cylindrical bodies (35, 45) are
different and a contact between them would cause a considerable
friction, preventing the rotation of the two rotors.
[0046] In order to remedy such a drawback, the diameter of the
cylindrical body (35) of the male rotor can be identical to the
diameter of the cylindrical body (45) of the female rotor. In this
way, the peripheral speed of the two cylindrical bodies (35, 45) of
the two rotors is identical and the tolerance between cylindrical
bodies (35, 45) of the two rotors may be zero, thus allowing for
contact between the cylindrical bodies (35, 45) of the two rotors
during rotation. Consequently, losses are minimized and high
rotational speeds are allowed. Moreover, in such a case, the
chamber (22) that houses the male rotor (3) is larger than the
chamber (23) that houses the female rotor (4), thus increasing the
delivery capacity of the pump (1), while maintaining the same size
of the protuberance module (31).
[0047] It must be noted that, because of the special configuration
of the cavities (40) of the female rotor and because there are no
contact parts between rotors (3, 4) and casing, the fluid is not
trapped in the pump (1) and the pump (1) can operate at a high
number of revolutions, thus reducing wear and failure of mechanical
parts.
[0048] As shown in FIG. 4, the male rotor (3) can be made in
different parts that are mutually assembled. For instance, seats
(36) are obtained in the cylindrical body (35), cross-sectionally
having a substantially C-shaped or dovetail profile.
[0049] In such a case, the protuberances (30) consist in sectors
provided with a substantially parallelepiped base (34) that is
engaged into the seat (36). The base (34) of the protuberance can
be provided with ribs or grooves (34') that are engaged with
corresponding ribs or grooves (36') provided in the seat (36) of
the cylindrical body of the male rotor.
[0050] The entire rotors (3, 4) or only the protuberances (30)
and/or cavities (40) can undergo thermal and/or chemical treatments
and can be coated with suitable materials, such as hard metal,
Widia, rubber, plastics, Teflon or ceramic.
[0051] As shown in FIG. 5, the pump (1) also comprises two seal
gaskets (9) composed of 8-shaped plates made of anti-friction
self-lubricating material. The seal gaskets (9) are disposed
between the central body (2) and the lids (20). The surface of the
lids facing towards the central body is provided with suitable
recessed seats (25) adapted to house the seal gaskets (9). Springs
(90) are disposed in the seats (25) of the lids in such manner to
stress the seal gaskets (9) towards the central body. In such a
way, the seal gaskets (9) are stopped against the planar sides of
the male and female rotors (3, 4). Such a solution provides for
tightness of the chambers (22, 23) obtained inside the central body
(20), thus avoiding losses due to construction tolerance. In this
way, if the rotors (3, 4) are coated with anti-friction
self-lubricating material, the pump (1) can be used at a high
number of revolutions, without oil and with minimum wear for
mechanical moving parts.
[0052] Variations and modifications can be made to the present
embodiments of the invention, within the reach of an expert of the
field, while still falling within the scope of the invention.
* * * * *