U.S. patent application number 12/973349 was filed with the patent office on 2012-06-21 for cam liner profile.
This patent application is currently assigned to HAMILTON SUNDSTRAND CORPORATION. Invention is credited to Sara Dexter, Weishun Ni.
Application Number | 20120156077 12/973349 |
Document ID | / |
Family ID | 46234690 |
Filed Date | 2012-06-21 |
United States Patent
Application |
20120156077 |
Kind Code |
A1 |
Dexter; Sara ; et
al. |
June 21, 2012 |
CAM LINER PROFILE
Abstract
A vane pump is provided and includes a liner having an inlet
window and a discharge window, the liner being formed to define a
cam surface and a rotor carrying a plurality of radially extending
vanes which are forced outwardly such that vane tips thereof
contact with the cam surface, the rotor having a direction of
rotation such that one end of the inlet window is an upstream end
and an opposed end is a downstream end, a radius of each of the
vane tips being approximately 0.114 inches (0.3 cm) and a profile
of the cam surface being defined in accordance with the radius of
the vane tips.
Inventors: |
Dexter; Sara; (Rockford,
IL) ; Ni; Weishun; (Rockton, IL) |
Assignee: |
HAMILTON SUNDSTRAND
CORPORATION
Windsor Locks
CT
|
Family ID: |
46234690 |
Appl. No.: |
12/973349 |
Filed: |
December 20, 2010 |
Current U.S.
Class: |
418/106 |
Current CPC
Class: |
F04C 2/3442 20130101;
F01C 21/0809 20130101; F01C 21/106 20130101; F04C 15/0011
20130101 |
Class at
Publication: |
418/106 |
International
Class: |
F01C 19/04 20060101
F01C019/04 |
Claims
1. A vane pump comprising: a liner having an inlet window and a
discharge window, the liner being formed to define a cam surface;
and a rotor carrying a plurality of radially extending vanes which
are forced outwardly such that vane tips thereof contact the cam
surface, the rotor having a direction of rotation such that one end
of the inlet window is an upstream end and an opposed end is a
downstream end, a radius of each of the vane tips being
approximately 0.114 inches (0.3 cm) and a profile of the cam
surface being defined in accordance with the radius of the vane
tips.
2. The vane pump according to claim 1, wherein the plurality of the
vanes comprises 4 vanes.
3. The vane pump according to claim 2, wherein each vane is
perpendicular to an adjacent vane.
4. The vane pump according to claim 1, wherein the profile of the
vane surface diverges from a profile of a tracing defined by each
of the vane tips as the rotor rotates.
5. The vane pump according to claim 4, wherein the divergence
occurs between the 45-135 and the 315-225 degree positions as
measured from a top-dead center of the cam surface profile.
6. The vane pump according to claim 1, wherein the inlet window is
formed as a plurality of inlet windows.
7. A vane pump comprising: a liner having an inlet window and a
discharge window, the liner being formed to define a cam surface;
and a rotor carrying a plurality of radially extending vanes which
are forced outwardly such that vane tips thereof contact the cam
surface, the rotor having a direction of rotation such that one end
of the inlet window is an upstream end and an opposed end is a
downstream end, a radius of each of the vane tips being
approximately 0.150 inches (0.4 cm) and a profile of the cam
surface being defined in accordance with the radius of the vane
tips.
8. The vane pump according to claim 7, wherein the plurality of the
vanes comprises 4 vanes.
9. The vane pump according to claim 8, wherein each vane is
perpendicular to an adjacent vane.
10. The vane pump according to claim 7, wherein the profile of the
vane surface diverges from a profile of a tracing defined by each
of the vane tips as the rotor rotates.
11. The vane pump according to claim 10, wherein the divergence
occurs between the 45-135 and the 315-225 degree positions as
measured from a top-dead center of the cam surface profile.
12. The vane pump according to claim 7, wherein the inlet window is
formed as a singular inlet window.
13. A vane pump comprising: a liner having an interior facing cam
surface and being formed to define an inlet window and a discharge
window; and a rotor disposed within the liner and carrying a
plurality of radially extending vanes which are forced outwardly
such that vane tips thereof contact the cam surface during rotor
rotation, the rotor having a direction of rotation such that
respective one ends of the inlet and outlet windows are upstream
ends and that respective opposed ends are downstream ends, a
profile of the cam surface being defined in accordance with the
radius of the vane tips such that the profile diverges from a
profile of a tracing defined by each of the vane tips as the rotor
rotates.
14. The vane pump according to claim 13, wherein the plurality of
the vanes comprises 4 vanes.
15. The vane pump according to claim 14, wherein each vane is
perpendicular to an adjacent vane.
16. The vane pump according to claim 13, wherein a radius of each
of the vane tips is approximately 0.114 inches (0.3 cm).
17. The vane pump according to claim 16, wherein the divergence
occurs between the 45-135 and the 315-225 degree positions as
measured from a top-dead center of the cam surface profile.
18. The vane pump according to claim 13, wherein the inlet window
is formed as a plurality of inlet windows.
19. The vane pump according to claim 13, wherein a radius of each
of the vane tips is approximately 0.150 inches (0.4 cm).
20. The vane pump according to claim 19, wherein the divergence
occurs between the 45-135 and the 315-225 degree positions as
measured from a top-dead center of the cam surface profile.
Description
BACKGROUND OF THE INVENTION
[0001] The subject matter disclosed herein relates to a vane pump
having a unique cam liner profile.
[0002] Vane pumps typically include a rotor carrying a plurality of
radially movable vanes. The vanes are urged outwardly into contact
with a cam surface. The cam surface may be formed within a liner,
which is mounted within an outer housing and which has a profile
such that the cam surface has a similar profile.
[0003] The rotor is mounted eccentrically within the cam surface,
such that the size of pump chambers increase and then decrease as
the rotor moves from an inlet portion of a cycle toward a discharge
portion. While the pump is moving through the inlet portion, fluid
moves in through an inlet window and is then discharged through an
outlet window after the pump cycle is completed.
[0004] There are stresses and forces on the vanes and the cam
surface from the interacting movement and pressure differentials
across the pump. There are particularly high contact stresses
formed on the cam surface at areas associated with the inlet window
and in particular at downstream ends of the inlet window.
BRIEF DESCRIPTION OF THE INVENTION
[0005] According to one aspect of the invention, a vane pump is
provided and includes a liner having an inlet window and a
discharge window, the liner being formed to define a cam surface
and a rotor carrying a plurality of radially extending vanes which
are forced outwardly such that vane tips thereof contact with the
cam surface, the rotor having a direction of rotation such that one
end of the inlet window is an upstream end and an opposed end is a
downstream end, a radius of each of the vane tips being
approximately 0.114 inches (0.3 cm) and a profile of the cam
surface being defined in accordance with the radius of the vane
tips.
[0006] According to another aspect of the invention, a vane pump is
provided and includes a liner having an inlet window and a
discharge window, the liner being formed to define a cam surface
and a rotor carrying a plurality of radially extending vanes which
are forced outwardly such that vane tips thereof contact with the
cam surface, the rotor having a direction of rotation such that one
end of the inlet window is an upstream end and an opposed end is a
downstream end, a radius of each of the vane tips being
approximately 0.150 inches (0.4 cm) and a profile of the cam
surface being defined in accordance with the radius of the vane
tips.
[0007] According to yet another aspect of the invention, a vane
pump is provided and includes a liner having an inlet window and a
discharge window, the liner being formed to define a cam surface
and a rotor carrying a plurality of radially extending vanes which
are forced outwardly such that vane tips thereof contact with the
cam surface, the rotor having a direction of rotation such that one
end of the inlet window is an upstream end and an opposed end is a
downstream end, a radius of each of the vane tips being within a
range of approximately 0.114 inches (0.3 cm) to approximately 0.150
inches (0.4 cm), inclusively, and a profile of the cam surface
being defined in accordance with the radius of the vane tips.
[0008] These and other advantages and features will become more
apparent from the following description taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The foregoing and other
features, and advantages of the invention are apparent from the
following detailed description taken in conjunction with the
accompanying drawings in which:
[0010] FIG. 1A shows a vane pump;
[0011] FIG. 1B shows a liner from the FIG. 1A vane pump;
[0012] FIG. 1C shows a liner in accordance with further
embodiments;
[0013] FIG. 2 shows an exemplary vane; and
[0014] FIG. 3 shows exemplary vane and cam liner profiles.
[0015] The detailed description explains embodiments of the
invention, together with advantages and features, by way of example
with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0016] A pump 20 is illustrated in FIG. 1A having a rotor 22
carrying a plurality of vanes 23 with vane tips 231. The vanes 23
are forced outwardly such that the vane tips 231 abut against a cam
surface 26, shown here as part of a liner 25. The vanes 23 are
oriented perpendicularly with respect to adjacent vanes 23. The
liner 25 has a substantially eccentric cylindrical shape with the
rotor 22 disposed in the liner 25 substantially parallel with a
longitudinal axis of the liner 25. The liner 25 is typically
mounted within a housing that has a supply of fluid to be pumped
toward inlet window 28.
[0017] Pump chambers 24 are formed between the cam surface 26, and
adjacent ones of the vanes 23. While not shown, the vanes 23 can
move radially inwardly and outwardly of the rotor 22. The rotor 22
is mounted eccentrically within the liner 25 and driven to rotate
such that the volume of the pump chambers 24 increases as it moves
through an inlet portion of a pump cycle, and over the inlet window
28, and then begin to decrease in accordance with movement toward a
discharge portion.
[0018] As shown in FIG. 1B, a discharge window 30 is formed
circumferentially spaced from the inlet window 28. As shown in FIG.
1C, multiple discharge windows 30 may be formed circumferentially
spaced from multiple inlet windows 28.
[0019] In standard models, a profile of the liner 25 (i.e., the
"cam liner profile") has been determined in accordance with a
modified trapezoidal cam profile of standard vane tips. For certain
applications, however, contact stresses between the vane tips 231
and the liner 25 were found to be excessively high. In accordance
with aspects and, with reference to FIG. 2, reduction of the
contact stresses is achieved by an increase of a radius, R.sub.T,
of the vane tips. Normally, when the tip radius, R.sub.T, becomes
too large, the vanes 23 are no longer able to follow the standard
cam liner profile due to geometric constraints and, as a result,
the vanes are pinched and lock inside the liner prohibiting further
rotation. Here, on the other hand, the standard cam liner profile
has been modified to allow for a larger vane tip radius and results
in the reduced contact stress by as much as 26%.
[0020] With reference to Table 1, these modifications are provided
in the "-6R114", the "-4HR114" and the "-8R150" columns and in
comparison to current, standard designs (i.e., the "-6", the "-4H"
and the "-8" columns)
TABLE-US-00001 TABLE 1 where the major and minor radii refer to
transverse radii of the cam liner profile and the displacement
value is calculated in accordance with the following equation: Disp
:= [.pi. (R.sup.2 - r.sup.2) - 4 (R - r) t] L Model -6 -4H -8 -6
R114 -4H R114 -8 R150 Major Radius 0.625 0.625 0.485 0.485 0.722
0.722 (inch) R Minor Radius 0.425 0.425 0.365 0.365 0.492 0.492
(inch) r Vane Thickness 0.093 0.093 0.093 0.093 0.093 0.093 (inch)
t Vane Tip Radius 0.062 0.114 0.062 0.114 0.114 0.150 (inch)
Displacement 0.5561 0.5561 0.4223 0.4223 1.21 1.21
(in.sup.3/rev)
[0021] That is, the "-4H", the "-6" and the "-8" are all standard
feature models and the "-6R114", the "-4HR114" and the "-8R150" are
modified with new tip radii and in some cases new vane lengths. For
the "-6R114" and the "-4R114" cases, two vane elements are needed
in order to meet minimum flow and, as such, the liner 25 of FIG. 1C
may be used. By contrast, one vane element is enough to meet the
minimum flow requirement in the "-8R150" case and, as such, the
liner 25 of FIG. 1B may be used.
TABLE-US-00002 TABLE 2 Model -6 -6 R114 -4H -4H R114 -8 -8 R150
Maximum Hertzian 65.67 48.74 69.11 50.58 51.52 46.26 Stress (Ksi)
Maximum PV Value 1.029E+08 7.33E+07 1.032E+08 7.14E+07 1.12E+08
9.51E+07 (psi-fpm)
[0022] In addition, with reference to Table 2, while the "-4H" and
"-6" standard models exhibited high characteristic Hertzian
stresses and high PV values, both the "-4HR114" and the "-6R114"
modified models had acceptable Hertzian stresses and PV values.
Further, while the "-8" standard model and the "-8R150" modified
model both had acceptable Hertzian stresses but high PV values, the
"-8R150" model can be employed with reduced operational speeds to
drop the PV value.
[0023] As described above and, in accordance with embodiments, the
radii, R.sub.T, of the vane tips 231 have been increased to between
0.114 inches (0.3 cm) to 0.150 inches (0.4 cm), inclusively. In
addition, the profile of the liner 25 has been modified as well.
With reference to FIG. 3, the modification to the liner 25 profile
is illustrated and, as shown in FIG. 3, it may be seen that the
liner profile (i.e., r.sub..cam(.theta.)) is similar to the profile
of the tracing defined by the vane tips 231 (i.e.,
r.sub..tip(.theta.)) as the rotor 22 rotates within the liner 25 up
to about the 45 and the 315 degree regions, as measured from a
top-dead center 251 of the liner 25. At the degree regions, the
profiles diverge from one another. The profiles re-converge at
around the 135 and the 225 degree regions. This has the effect of
fattening the liner 25 profile around the 45-135 and the 315-225
degree regions.
[0024] With the profiles divergent from one another in the 45-135
and the 315-225 degree regions, the vanes 23 having increased vane
tip 231 radii are removed from contact with the cam surface 26.
This removal from contact reduces the stresses and the PV values of
the modified models that would otherwise be generated.
[0025] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *