Title: Extra support area for valve disc
Abstract: A valve for controlling fluid flow through a passage defined by a valve body or a piston includes a valve disc which abuts the valve body or the piston. The valve body or the piston defines a first land for supporting the valve disc, a second land for supporting the valve disc located radially inward from the first land and a support surface for the valve disc located between the first and second lands. This valve disc abuts the first and second lands and a clearance is defined between the valve disc and the support surface.
Patent Number: 6,899,207 Issued on 05/31/2005 to Deferme, et al.
| Inventors:
|
Deferme; Stefan (Heusden-Zolder, BE);
Tuts; Jean-Marie (Wellen, BE);
Mangelschots; Gert (Heusden-Zolder, BE);
Vanmechelen; Patrick (Sint-Truiden, BE)
|
| Assignee:
|
Tenneco Automotive Operating Company Inc. (Lake Forest, IL)
|
| Appl. No.:
|
674161 |
| Filed:
|
September 29, 2003 |
| Current U.S. Class: |
188/282.5; 188/282.6; 188/322.14 |
| Intern'l Class: |
F16F 009/34.8 |
| Field of Search: |
188/2825,322.14,322.13,322.15,322.19,322.22,282.6
|
References Cited [Referenced By]
U.S. Patent Documents
| 3550616 | Dec., 1970 | Graham.
| |
| 3572377 | Mar., 1971 | Graham et al.
| |
| 4782925 | Nov., 1988 | Grundei.
| |
| 5042624 | Aug., 1991 | Furuya et al.
| |
| 5085300 | Feb., 1992 | Kato et al.
| |
| 5115892 | May., 1992 | Yamaoka et al.
| |
| 5219414 | Jun., 1993 | Yamaoka.
| |
| 5325942 | Jul., 1994 | Groves et al.
| |
| 5424398 | Jun., 1995 | Middeldorp et al.
| |
| 5813500 | Sep., 1998 | Deferme.
| |
| 6382372 | May., 2002 | Keil et al.
| |
| 6672436 | Jan., 2004 | Keil et al.
| |
Primary Examiner: Siconolfi; Robert A.
Assistant Examiner: Torres; Melanie
Attorney, Agent or Firm: Harness, Dickey & Pierce, PLC
Claims
1. A damper comprising:
a pressure tube forming a working chamber;
a reservoir tube disposed around said pressure tube, said reservoir tube forming
a reservoir chamber between said pressure tube and said reservoir tube;
a base valve assembly disposed between said working chamber and said reservoir
chamber, said base valve assembly comprising;
a valve body defining a fluid passage, said valve body defining a first land,
a second land disposed radially inward from said first land, and a support surface
disposed between said first and second lands; and
a valve disc disposed adjacent said valve body, said valve disc abutting said
first and second lands, said valve disc being movable between a first position
where said valve disc contacts said first and second lands and forms a clearance
with said entire support surface and a second position where said valve disc contacts
said first and second lands and said support surface.
2. The damper according to claim 1 wherein said first and second lands are annular
in shape.
3. The damper according to claim 2 further comprising a biasing member for urging
said valve disc towards said valve body.
4. The damper according to claim 2 wherein said support surface defines a circular
inner edge.
5. The damper according to claim 4 wherein said support surface defines a scalloped
outer edge.
6. The damper according to claim 2 wherein said support surface defines a scalloped
outer edge.
7. The damper according to claim 1 further comprising a biasing member for urging
said valve disc towards said valve body.
8. The damper according to claim 1 wherein said support surface defines a circular
inner edge.
9. The damper according to claim 8 wherein said support surface defines a scalloped
outer edge.
10. The damper according to claim 1 wherein said support surface defines a scalloped
outer edge.
11. A damper comprising:
a pressure tube forming a working chamber;
a piston disposed within said working chamber, said piston dividing said working
chamber into an upper working chamber and a lower working chamber, said piston
defining a first land, a second land disposed radially inward from said first land
and a support surface disposed between said first and second lands; and
a valve disc disposed adjacent said piston, said valve disc abutting said first
and second lands, said valve disc being movable between a first position where
said valve disc contacts said first and second lands and forms a clearance with
said entire support surface and a second position where said valve disc contacts
said first and second lands and said support surface.
12. The damper according to claim 11 wherein said first and second lands are
annular in shape.
13. The damper according to claim 12 further comprising a biasing member for
urging said valve disc towards said valve body.
14. The damper according to claim 12 wherein said support surface defines a circular
inner edge.
15. The damper according to claim 14 wherein said support surface defines a scalloped
outer edge.
16. The damper according to claim 12 wherein said support surface defines a scalloped
outer edge.
17. The damper according to claim 11 further comprising a biasing member for
urging said valve disc towards said valve body.
18. The damper according to claim 17 wherein said support surface defines a circular
inner edge.
19. The damper according to claim 18 wherein said support surface defines a scalloped
outer edge.
20. The damper according to claim 11 wherein said support surface defines a scalloped
outer edge.
Description
FIELD OF THE INVENTION
The present invention relates generally to shock absorbers having a unique check
valve assembly for use with a base valve assembly or a piston valve assembly. More
particularly, the present invention relates to a shock absorber having a check
valve assembly which includes an additional area on the valve body to support and
protect a valve disc against damage due to high fluid pressures.
BACKGROUND OF THE INVENTION
Shock absorbers are used in conjunction with automotive suspension systems
and other suspension systems to absorb unwanted vibrations which occur during movement
of the suspension system. In order to absorb these unwanted vibrations, automotive
shock absorbers are generally connected between the sprung (body) and the unsprung
(suspension/chassis) masses of the vehicle.
The most common type of shock absorbers for automobiles is the dashpot type which
can be either a mono-tube design or a dual-tube design. In the mono-tube design,
a piston is located within a pressure tube and is connected to the spring mass
of the vehicle through a piston rod. The pressure tube is connected to the unsprung
mass of the vehicle. The piston divides the pressure tube into an upper working
chamber and a lower working chamber. The piston includes compression valving which
limits the flow of damping fluid from the lower working chamber during a compression
stroke and rebound valving which limits the flow of damping fluid from the upper
working chamber to the lower working chamber during a rebound or extension stroke.
Because the compression valving and the rebound valving have the ability to limit
the flow of damping fluid, the shock absorber is able to produce a damping force
which counteracts the vibrations which would otherwise be transmitted from the
unsprung mass to the sprung mass.
In a dual-tube shock absorber, a fluid reservoir is defined between the pressure
tube and a reservoir tube which is positioned around the pressure tube. A base
valve assembly is located between the lower working chamber and the fluid reservoir
to control the flow of dampening fluid. The compression valving of the piston is
moved to the base valve assembly and is replaced by a compression check valve assembly.
In addition to the compression valving, the base valve assembly includes a rebound
check valve assembly. The compression valving of the base valve assembly produces
the damping force during a compression stroke, and the rebound valving of the piston
produces the damping force during a rebound or extension stroke. Both the compression
and rebound check valve assemblies permit fluid flow in one direction, but prohibit
fluid flow in an opposite direction; however, they are designed such that they
do not generate a damping force.
In applications where a low level of flow restriction is a priority for the check
valve assemblies, the working surface for lifting the check valve disc must be
maximized. In addition, this low flow restriction level also calls for a very lightweight
disc. When first reviewing the design for the check valve assembly, it may seem
logical to utilize a valve spring, which has a low stiffness. This design choice
is overruled by the need for a fast closing check valve assembly, as well as the
need to avoid "chuckle" noise when the shock absorber is mounted on the vehicle.
As the check valve disc becomes lighter and thinner, and the area of the check
valve disc which is acted upon by fluid pressure becomes greater, the check valve
disc becomes very sensitive to the high fluid pressure which urges the check valve
assembly into its closed position.
The continued development of check valve assemblies has been directed towards
reducing the level of flow restriction without compromising the sensitivity of
the check valve assembly to the high pressure fluid which urges the check valve
assembly into its closed position.
SUMMARY OF THE INVENTION
The present invention provides the art with a valve body which includes a surface
or support area that supports the check valve disc. The surface or support area
is designed to distribute the load from the high pressure fluid over a greater
surface area, instead of just two lands to reduce the unsupported span of the disc.
In order to maximize the working surface which reacts to open the check valve assembly,
a clearance is provided between the surface or support area and the check valve disc.
Further areas of applicability of the present invention will become apparent
from the detailed description provided hereinafter. It should be understood that
the detailed description and specific examples, while indicating the preferred
embodiment of the invention, are intended for purposes of illustration only and
are not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description
and the accompanying drawings, wherein:
FIG. 1 is a schematic representation of a typical automobile which incorporates
the unique base valve assembly in accordance with the present invention;
FIG. 2 is a side sectional view of the shock absorber in accordance with the
present invention;
FIG. 3 is an enlarged cross-sectional view of the piston assembly in accordance
with the present invention;
FIG. 4 is a perspective view of the piston in the compression check valve assembly
shown in FIG. 3;
FIG. 5 is an enlarged cross-sectional view of the base valve assembly in accordance
with the present invention; and
FIG. 6 is an exploded perspective view of the rebound check valve assembly shown
in FIG. 5; and
FIG. 6
a is a perspective view of the valve body in the rebound check
valve assembly shown in FIGS. 5 and 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following description of the preferred embodiment(s) is merely exemplary
in nature and is in no way intended to limit the invention, its application, or uses.
Referring now to the drawings in which like reference numerals designate
like or corresponding parts throughout the several views, there is shown in FIG.
1 a vehicle which includes a suspension system incorporating the unique shock absorbers
in accordance with the present invention and which is designated generally by the
reference numeral
10. Vehicle
10 includes a rear suspension
12,
a front suspension
14 and a body
16. Rear suspension
12 has
a transversely extending rear axle assembly (not shown) adapted to operatively
support a pair of rear wheels
18 of vehicle
10. The rear axle assembly
is operatively connected to body
16 by means of a pair of shock absorbers
20 and a pair of helical coil springs
22. Similarly, front suspension
14 includes a transversely extending front axle assembly (not shown) to
operatively support a pair of front wheels
24 of vehicle
10. The
front axle assembly is operatively connected to body
16 by means of a second
pair of shock absorbers
26 and by a pair of helical coil springs
28.
Shock absorbers
20 and
26 serve to dampen the relative motion of
the unsprung mass (i.e., front and rear suspensions
12 and
14, respectively)
and the sprung mass (i.e., body
16) of vehicle
10. While vehicle
10 has been depicted as a passenger car having front and rear axle assemblies,
shock absorbers
20 and
26 may be used with other types of vehicles
or in other types of applications such as vehicles incorporating independent front
and/or independent rear suspension systems. Further, the term "shock absorber"
as used herein is meant to refer to dampers in general and thus will include MacPherson struts.
Referring now to FIG. 2, shock absorber
20 is shown in greater detail.
While FIG. 2 illustrates only shock absorber
20, it is to be understood
that shock absorber
26 also includes the unique valve assembly described
below for shock absorber
20. Shock absorber
26 only differs from
shock absorber
20 in the manner in which it is adapted to be connected to
the sprung and unsprung masses of vehicle
10. Shock absorber
20 comprises
a pressure tube
30, a piston assembly
32, a piston rod
34,
a reservoir tube
36 and a base valve assembly
38.
Pressure tube
30 defines a working chamber
42. Piston assembly
32 is slidably disposed within pressure tube
30 and divides working
chamber
42 into an upper working chamber
44 and a lower working chamber
46. A seal
48 is disposed between piston assembly
32 and pressure
tube
30 to permit sliding movement of piston assembly
32 with respect
to pressure tube
30 without generating undue frictional forces as well as
sealing upper working chamber
44 from lower working chamber
46. Piston
rod
34 is attached to piston assembly
32 and extends through upper
working chamber
44 and through upper end cap
50 which closes the
upper end of pressure tube
30. A sealing system seals the interface between
upper end cap
50, reserve tube
36 and piston rod
34. The end
of piston rod
34 opposite to piston assembly
32 is adapted to be
secured to the sprung portion of vehicle
10. Valving within piston assembly
32 controls the movement of fluid between upper working chamber
44
and lower working chamber
46 during movement of piston assembly
32
within pressure tube
30. Because piston rod
34 extends only through
upper working chamber
44 and not lower working chamber
46, movement
of piston assembly
32 with respect to pressure tube
30 causes a difference
in the amount of fluid displaced in upper working chamber
44 and the amount
of fluid displaced in lower working chamber
46. The difference in the amount
of fluid displaced is known as the "rod volume" and it flows through base valve
assembly
38.
Reservoir tube
36 surrounds pressure tube
30 to define a
fluid reservoir chamber
52 located between tubes
30 and
36.
The bottom end of reservoir tube
36 is closed by an end cap
54 which
is adapted to be connected to the unsprung portion of vehicle
10. The upper
end of reservoir tube
36 is attached to upper end cap
50. Base valve
assembly
38 is disposed between lower working chamber
46 and reservoir
chamber
52 to control the flow of fluid between chambers
46 and
52.
When shock absorber
20 extends in length, an additional volume of fluid
is needed in lower working chamber
46 due to the "rod volume" concept. Thus,
fluid will flow from reservoir chamber
52 to lower working chamber
46
through base valve assembly
38 as detailed below. When shock absorber
20
compresses in length, an excess of fluid must be removed from lower working chamber
46 due to the "rod volume" concept. Thus, fluid will flow from lower working
chamber
46 to reservoir chamber
52 through base valve assembly
38
as detailed below.
Referring now to FIG. 3, piston assembly
32 comprises a valve body
60, a compression check valve assembly
62 and a rebound valve assembly
64. Compression check valve assembly
62 is assembled against a shoulder
66 on piston rod
34. Valve body
60 is assembled against compression
check valve assembly
62 and rebound valve assembly
64 is assembled
against valve body
60. A nut
68 secures these components to piston
rod
34.
Valve body
60 defines a plurality of compression passages
70
and a plurality of rebound passages
72. Seal
48 includes a plurality
of ribs
74 which mate with a plurality of annular grooves
76 to permit
sliding movement of piston assembly
32.
Compression check valve assembly
62 comprises a retainer
78,
a valve disc
80 and a spring
82. Retainer
78 abuts shoulder
66 on one end and valve body
60 on the other end. Valve disc
80
abuts valve body
60 and closes compression passages
70 while leaving
rebound passages
72 open. Spring
82 is disposed between retainer
78 and valve disc
80 to bias valve disc
80 against valve body
60. During a compression stroke, fluid in lower working chamber
46
is pressurized causing fluid pressure to react against valve disc
80. When
the fluid pressure against valve disc
80 overcomes the biasing load of spring
82, valve disc
80 separates from valve body
60 to open compression
passages
70 and allow fluid flow from lower working chamber to upper working
chamber. Typically spring
82 only exerts a light load on valve disc
80,
and it does not contribute to the damping characteristics for shock absorber
20.
The damping characteristics for shock absorber
20 during a compression stroke
are controlled by base valve assembly
38 which accommodates the flow of
fluid from lower working chamber
46 to reservoir chamber
52 due to
the "rod volume" concept as detailed below. During a rebound stroke, compression
passages
70 are closed by valve disc
80.
Rebound valve assembly
64 comprises a spacer
84, a plurality
of valve discs
86, a retainer
88 and a Belleville spring
90.
Spacer
84 is threadingly or slidingly received on piston rod
34 and
is disposed between valve body
60 and nut
68. Spacer
84 retains
valve body
60 and compression check valve assembly
62 while permitting
the tightening of nut
68 without compressing either valve disc
80
or valve discs
86. Retainer
78, valve body
60 and spacer
84
provide a continuous solid connection between shoulder
66 and nut
68
to facilitate the tightening and securing of nut
68 to spacer
84
and thus to piston rod
34. Valve discs
86 are slidingly received
on spacer
84 and abut valve body
60 to close rebound passages
72
while leaving compression passages
70 open. Retainer
88 is also slidingly
received on spacer
84 and it abuts valve discs
86. Belleville spring
90 is assembled over spacer
84 and is disposed between retainer
88
and nut
68 which is threadingly received on spacer
84. Belleville
spring
90 biases retainer
88 against valve discs
86 and valve
discs
86 against valve body
60. The plurality of valve discs
86
comprise a bleed disc
92, a valve disc
94, a spacer disc
96
and a fulcrum disc
98. Bleed disc
92 includes at least one slot
100
which permits a limited amount of bleed flow bypassing rebound valve assembly
64.
Fulcrum disc
98 provides a fulcrum or bending point for bleed disc
92,
valve disc
94 and spacer disc
96. When fluid pressure is applied
to discs
92 and
94, they will elastically deflect at the outer peripheral
edge of spacer disc
96 and fulcrum disc
98 to open rebound valve
assembly
64. A shim
102 is located between nut
68 and Belleville
spring
90 to control the preload for Belleville spring
90 and thus
the blow off pressure as described below. Thus, the calibration for the blow off
feature of rebound valve assembly
64 is separate from the calibration for
compression check valve assembly
62.
During a rebound stroke, fluid in upper working chamber
44 is pressurized
causing fluid pressure to react against valve discs
86. When the fluid pressure
reacting against valve discs
86 overcomes the bending load for valve discs
86, valve discs
86 elastically deflect opening rebound passages
72
allowing fluid flow from upper working chamber
44 to lower working chamber
46. The strength of valve discs
86 and the size of rebound passages
will determine the damping characteristics for shock absorber
20 in rebound.
Prior to the deflection of valve discs
86, a controlled amount of fluid
flows from upper working chamber
44 to lower working chamber
46 through
slot
100 to provide low speed tunability. When the fluid pressure within
upper working chamber
44 reaches a predetermined level, the fluid pressure
will overcome the biasing load of Belleville spring
90 causing axial movement
of retainer
88 and the plurality of valve discs
86. The axial movement
of retainer
88 and valve discs
86 fully opens rebound passages
72
thus allowing the passage of a significant amount of damping fluid creating a blowing
off of the fluid pressure which is required to prevent damage to shock absorber
20 and/or vehicle
10.
Referring now to FIGS. 3 and 4, compression check valve assembly
62
is designed to provide a low restriction to the flow of fluid from lower working
chamber
46 to upper working chamber
44, and it is designed to maximize
the working surface for lifting valve disc
80. Valve body
60 defines
a first or outer land
104, a second or inner land
106, and a support
surface
108 disposed between outer land
104 and inner land
106.
Support surface
108 is defined by an inner diameter
110, which is
adjacent inner land
106, and a scalloped outer surface
112, which
defines a plurality of indentations
114 which partially surround each of
the plurality of rebound passages
72, to maximize the surface area of support
surface
108. Valve disc
80 is biased by spring
82 against
outer land
104 and inner land
106. A clearance is provided between
support surface
108 and valve disc
80. This clearance maximizes the
working surface during the compression stroke by allowing fluid pressure in lower
working chamber
46 to react against the surface area of valve disc
80,
which is between outer land
104 and inner land
106. This provides
for a low level of intake restriction for compression check valve assembly
62.
During a rebound stroke, fluid pressure within upper working chamber
44
reacts against the upper surface of valve disc
80. Due to valve disc
80
being designed thin to reduce its weight, valve disc
80 will deflect in
the area between outer land
104 and inner land
106 to contact support
surface
108, which provides additional support for valve disc
80.
Support surface
108 supports valve disc
80 during the rebound stroke
to minimize the unsupported span of valve disc
80 by distributing the load
over lands
104 and
106, as well as the entire surface area of support
surface
108.
Referring now to FIG. 5, base valve assembly
38 comprises a valve
body
120, an intake or rebound check valve assembly
122, a compression
valve assembly
124, a retaining bolt
126 and a retaining nut
128.
Valve body
120 is secured to pressure tube
30 and end cap
54
by press fitting or by other methods known well in the art. End cap
54 is
secured to reservoir tube
36 and it defines a plurality of fluid passages
130 which allow communication between reservoir chamber
52 and base
valve assembly
38. Valve body
120 defines a plurality of intake or
rebound fluid passages
132, a plurality of compression passages
134,
and a central bore
138. Retaining bolt
126 extends through central
bore
138 and threadingly engages retaining nut
128 to secure both
intake valve assembly
122 and compression valve assembly
124 to valve
body
120.
Rebound check valve assembly
122 comprises a valve disc
140
and a valve spring
142. Valve disc
140 is an annular member which
defines an internal bore
144 for allowing fluid flow to reach compression
passages
134 as described below. Valve disc
140 is biased against
the upper surface of valve body
120 by valve spring
142 which is
located between valve disc
140 and retaining nut
128. Valve disc
140 closes the plurality of rebound fluid passages
132. During a
rebound stroke of shock absorber
20, fluid pressure decreases in lower working
chamber
46 until the fluid pressure within reservoir chamber
52 and
rebound fluid passages
132 is capable of overcoming the biasing force of
valve spring
142. When the biasing force exerted by valve spring
142
is exceeded by fluid pressure acting against valve disc
140, valve disc
140 is moved away from valve body
120 to allow fluid flow from reservoir
chamber
52 to lower working chamber
46.
Compression valve assembly
124 comprises one or more mid/high
speed valve discs
150, one or more ported restriction discs
152 and
one or more variable orifice bleed discs
154. Discs
150,
152
and
154 are stacked together and located adjacent to valve body
120
with mid/high speed valve disc
150 abutting valve body
120, ported
restriction disc
152 abutting mid/high speed valve disc
150 and variable
orifice bleed disc
154 abutting ported restriction disc
152. Discs
150,
152 and
154 are held in position by being sandwiched
between a shoulder
156 located on retaining bolt
126 and the lower
surface of valve body
120. Retaining bolt
126 is secured to valve
body
120 by retaining nut
128.
During a compression stroke, fluid pressure increases in lower working chamber
46 causing a fluid pressure decrease in upper working chamber
44
causing a pressure imbalance between lower working chamber
46 and reservoir
chamber
52. This pressure imbalance will cause fluid flow to begin through
the low speed oil flow circuit defined by compression valve assembly
124.
Fluid pressure builds up in lower working chamber
46 until such a time that
the fluid pressure in lower working chamber
46 acts against valve disc
154
and overcomes the load necessary to deflect disc valve
154 and allow fluid
flow between lower working chamber
46 and reservoir chamber
52. Once
the low speed oil flow circuit is saturated by fluid flow rate, fluid pressure
builds up in lower working chamber
46 until the pressure acting against
the mid/high speed valve discs
150 overcomes the load required to deflect
discs
150 and allow fluid flow from lower working chamber
46 to reservoir
chamber
52.
Referring now to FIGS. 5 and 6, rebound check valve assembly
122
is designed to provide a low restriction to the flow of fluid from reservoir chamber
52 to lower working chamber
46, and it is designed to maximize the
working surface for lifting valve disc
140. Valve body
120 defines
a first or outer land
174, a second or inner land
176, and a support
surface
178 disposed between outer land
174 and inner land
176.
Support surface
178 is defined by an inner diameter
180, which is
adjacent inner land
176, and a scalloped outer surface
182, which
defines a plurality of indentations
184, which partially surround each of
the plurality of rebound passages
132 to maximize the surface area of support
surface
178. Valve disc
140 is biased by valve spring
142
against outer land
174 and inner land
176. A clearance is provided
between support surface
178 and valve disc
140. This clearance maximizes
the working surface during the rebound stroke by allowing fluid pressure in reservoir
chamber
52 to react against the surface are of valve disc
140, which
is between outer land
174 and inner land
176. This provides for a
low level of intake restriction for rebound check valve assembly
122. During
a compression stroke, fluid pressure within lower working chamber
46 reacts
against the upper surface of valve disc
140. Due to valve disc
140
being designed thin to reduce its weight, valve disc
140 will deflect in
the area between outer land
174 and inner land
176 to contact support
surface
178, which provides additional support for valve disc
140.
Support surface
178 supports valve disc
140 during the rebound stroke
to minimize the unsupported span of valve disc
140 by distributing the load
over all lands
174 and
176, as well as the entire surface area of
support surface
178.
The description of the invention is merely exemplary in nature and, thus, variations
that do not depart from the gist of the invention are intended to be within the
scope of the invention. Such variations are not to be regarded as a departure from
the spirit and scope of the invention.
*
