U.S. patent application number 11/764267 was filed with the patent office on 2008-12-18 for web-less valve plate.
This patent application is currently assigned to SAUER-DANFOSS INC.. Invention is credited to Joseph Wright.
Application Number | 20080307956 11/764267 |
Document ID | / |
Family ID | 40030950 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080307956 |
Kind Code |
A1 |
Wright; Joseph |
December 18, 2008 |
WEB-LESS VALVE PLATE
Abstract
A hydraulic unit that uses first and second support structures
to eliminate the use of webs within an arcuate inlet and outlet of
a valve plate. Specifically, a valve plate body extends between an
inner and outer diameter wherein the outer diameter in a first
position is placed in close proximity to a first support structure
and the inner diameter is placed in close proximity to a second
support structure. Thus, stress of hydraulic fluid flowing through
the arcuate inlet or outlet deflects the inner and outer diameters
causing them to engage the first and second support structures such
that stress is passed to the first and second support structures
and the valve plate is stiffened.
Inventors: |
Wright; Joseph; (Ames,
IA) |
Correspondence
Address: |
ZARLEY LAW FIRM P.L.C.
CAPITAL SQUARE, 400 LOCUST, SUITE 200
DES MOINES
IA
50309-2350
US
|
Assignee: |
SAUER-DANFOSS INC.
Ames
IA
|
Family ID: |
40030950 |
Appl. No.: |
11/764267 |
Filed: |
June 18, 2007 |
Current U.S.
Class: |
92/163 |
Current CPC
Class: |
F04B 1/2042
20130101 |
Class at
Publication: |
92/163 |
International
Class: |
F01B 31/00 20060101
F01B031/00 |
Claims
1. A hydraulic unit comprising: a first support structure having an
opening therein; a valve plate detachably disposed within the
opening and having an outer diameter adjacent the first support
structure in a first position and an inner diameter surrounding a
valve plate opening; said valve plate having a body extending
between the inner diameter and outer diameter, said body having an
arcuate inlet and an arcuate outlet; a second support structure
detachably disposed within the valve plate opening adjacent the
inner diameter in the first position; wherein when above a
threshold stress level the inner diameter deflects to engage the
second support structure and the outer diameter deflects to engage
the first support structure to provide a second position; and
wherein stress is transferred from the body to the first and second
support structures in the second position.
2. The hydraulic unit of claim 1 wherein the first support
structure is a yoke.
3. The hydraulic unit of claim 2 wherein the second support
structure is a spindle.
4. The hydraulic unit of claim 1 wherein in the first position the
outer diameter of the valve plate is positioned at or less than 0.1
mm from the first support structure to form a first clearance.
5. The hydraulic unit of claim 4 wherein in the first position the
inner diameter of the valve plate is positioned at or less than 0.1
mm from the first support structure to form a second clearance.
6. The hydraulic unit of claim 1 wherein the first support
structure is an end cap.
7. The hydraulic unit of claim 6 wherein the second support
structure is a bearing.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to hydraulic units. More
specifically, this invention relates to a web-less valve plate for
a hydraulic unit.
[0002] Hydraulic units such as axial piston hydraulic units or bent
axis hydraulic units, including pumps and motors, are known in the
art. Each of these types of hydraulic units use valve plates
therein that have arcuate openings that represent inlet and outlet
ports. Specifically, each of these openings as shown in FIG. 1
contains a web portion therebetween to enhance the strength of the
valve plate to account for pressure variations known in current
hydraulic unit technology.
[0003] When hydraulic units were originally designed, as shown in
U.S. Pat. No. 2,915,985 valve plates included non restricted inlet
and outlet passages that were arcuate in shape and did not contain
the webs. As performance of hydraulic units increased with higher
operating pressures valve plates of this design became susceptible
to failure in the area of the pressurized outlet passage. To
eliminate this failure the strength enforcing webs as shown in FIG.
1 were added. An illustration of this is also seen in U.S. Pat. No.
3,249,061.
[0004] Though the webs assist in preventing failure of the
pressurized outlet passage of the valve plate the webs restrict
flow thus creating operating inefficiencies within the hydraulic
unit. Attempts have been made to overcome these operating
inefficiencies including creating openings within the webs
themselves and using special strength materials to make the valve
plates themselves stronger in an attempt to minimize the effects of
the webs on fluid flow.
[0005] Despite these improvements, problems still remain in the
art. Specifically, hydraulic units that attempt to overcome the
problems associated with the webs that merely add extra openings
within the webs weaken the valve plate making the valve plate
susceptible to failure. These valve plates also do not eliminate
the web completely and thus hamper fluid flow causing
inefficiencies within the hydraulic unit. In regard to valve plates
that use specialized materials extra steps are added to the
manufacturing process to accommodate the complexity of the
manufacturing of the valve plate causing additional expense and
time.
[0006] Therefore, a principal object of the present invention is to
provide a hydraulic unit with a valve plate that maximizes
efficiency of the hydraulic unit.
[0007] Yet another object of the present invention is to provide a
hydraulic unit with a valve plate assembly that reinforces the
ability of the valve plate to undergo stress.
[0008] These and other objects, features, or advantages of the
present invention will become apparent from the specification and
claims.
BRIEF SUMMARY OF THE INVENTION
[0009] A hydraulic unit having a first support structure with an
opening therein. A valve plate is detachably disposed within the
opening of the first support structure. Specifically, the valve
plate has an inner and outer diameter with a body extending
therebetween. The outer diameter in a first position is placed
adjacent and in close proximity to the first support structure
whereas the inner diameter surrounds a valve plate opening. Said
valve plate body also has an arcuate inlet and outlet disposed
therein. Additionally, in the first position a second support
structure is detachably disposed within the valve plate opening.
When fluid flows through the arcuate inlet and outlet the body of
the valve plate deflects such that the inner diameter engages the
second support structure and the outer diameter engages the first
support structure to provide a second position. In this second
position stress on the valve plate body is transferred from the
body to the first and second support structures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a prior art bottom plan view of a valve plate with
webs;
[0011] FIG. 2 is a bottom sectional plan view of a valve plate
within a hydraulic unit;
[0012] FIG. 3 is a bottom sectional plan view of a valve plate
within a hydraulic unit in a second position; and
[0013] FIG. 4 is a graphical representation of pressure as it
relates to stress on a valve plate.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] FIG. 2 shows a sectional view of a valve assembly 10 of a
hydraulic unit in a first position. Though the hydraulic unit is
not shown, the hydraulic unit could be of any type such as an axial
piston hydraulic unit utilizing a swashplate as is shown U.S. Pat.
No. 6,640,687 to Frantz et al. and U.S. Pat. No. 6,688,417 to
Hansell, both of which are incorporated herein. Similarly, the
hydraulic unit could be a bent axis unit as is shown in U.S. Pat.
No. 6,203,283 to Fleming et al. and U.S. Pat. No. 1,137,283 to
Pratt, both of which are also incorporated herein. Furthermore, the
hydraulic unit could be either a pump or a motor and not fall
outside of the scope of the disclosure.
[0015] The valve assembly 10 comprises a first support structure 12
that has an opening 14 disposed therein. The first support
structure 12 in a bent axis unit is a yoke whereas in another
embodiment the first support structure 12 is an end cap in an axial
piston unit.
[0016] Disposed within the opening 14 of the first support
structure 12 is a valve plate 16. The valve plate 16 has a body 18
that extends between an inner diameter 20 and an outer diameter 22.
The inner diameter 20 surrounds a valve plate opening 24. The body
18 additionally has an arcuate inlet 26 and an arcuate outlet 28
both disposed between the inner diameter 20 and the outer diameter
22. When fluid passes through the arcuate inlet and outlet 26, 28
stresses are placed upon the perimeters of each.
[0017] Disposed within the valve plate opening 24 is a second
support structure 30. In one embodiment, in a bent axis unit, the
second support structure is a spindle. In another embodiment in an
axial piston unit the second support structure is a bearing.
[0018] When manufactured the valve plate 16 is made of size and
shape such that when placed in a first position disposed within the
opening 14 (FIG. 2) of the first support structure 12 a first and
second clearance 32, 34 are created between the valve plate 16 and
the first support structure 12 and the second support structure 30
respectively. Specifically, in a first position as shown in FIG. 2,
when minimal pressure is placed upon the arcuate inlet and outlet
26, 28 the outer diameter 22 is detachably placed adjacent the
first support structure 12 within the opening 14. Thus, in the
first position the outer diameter 22 of the body 18 is in close
proximity to the first support structure 12. The distance between
the outer diameter 22 and the first support structure 12 is
considered the first clearance 32. In a preferred embodiment the
first clearance is equal to or less than 0.1 mm.
[0019] Similarly, when in the first position as seen in FIG. 2 the
valve plate 16 is placed such that the inner diameter 20 is
detachably disposed adjacent and in close proximity to the second
support structure 30. Specifically, the distance between the inner
diameter 20 and the second support structure 30 is considered the
second clearance 34. In a preferred embodiment the second clearance
34 is equal to or less than 0.1 mm.
[0020] During operation of the hydraulic unit when fluid flows
through the arcuate inlet and outlet 26, 28 stresses are applied to
the valve body 18. Upon reaching a threshold stress level the inner
diameter 20 and outer diameter 22 deflect away from the inlet and
outlet 26, 28 toward the first support structure and second support
structure 12, 30. The inner diameter 20 deflects until engaging the
second support structure whereas the outer diameter 22 deflects
until engaging the first support structure 12. Once the inner
diameter 20 or the outer diameter 22 engages the first support
structure 12 or second support structure 30 or both the valve
assembly 10 is considered in a second position.
[0021] In the second position because either the inner or outer
diameters 20, 22 are engaged by either the first or second support
structures 12, 30 added stiffness is provided to the valve plate
body 18. Thus, when in a second position stress is transferred from
the body 18 to either the first or second support structures or
both 12, 30 to prevent failure of the valve plate 16 at the arcuate
inlet and outlet 26, 28.
[0022] FIG. 4 shows a graph of the pressure 35a versus the stress
35b upon the valve plate body 18 during operation. In the first
position as shown by line 36 the inner and outer diameters are not
engaging the first or second support structures. Consequently, as
pressure rises, stress rises at a rapid rate. Then at point 38 that
represents placement in the second position of the valve plate 16
wherein the inner or outer diameter 20, 22 engage the first or
second support members the rate at which the stress rises is
greatly reduced as shown by line 40.
[0023] By providing first and second support structures 12, 30 in
close proximity to the inner and outer diameters 20, 22 of the
valve plate body 18 in a second position the valve plate body 18 is
able to engage the first and second support structures 12, 30 for
additional support to prevent failure. This occurs without the need
of placing webs within the arcuate inlet or outlet 26, 28 and
consequently maximum fluid flow is allowed through the inlet and
outlet 26, 28 maximizing the efficiency of the hydraulic unit.
Additionally, the amount of support provided can be customized for
each design by optimizing clearance 32, 34 and stiffness of the
valve plate and support members to provide support above a desired
pressure level. Consequently, at the very least all of the stated
objectives have been met.
[0024] It will be appreciated by those skilled in the art that
other various modifications could be made to the device without the
parting from the spirit in scope of this invention. All such
modifications and changes fall within the scope of the claims and
are intended to be covered thereby.
* * * * *