WO2000045673A1

WO2000045673A1 - Pneumatic system sound attenuator

Info

Publication number: WO2000045673A1
Application number: PCT/US2000/003034
Authority: WO
Inventors: William Ouellette; Howard Schmidt
Original assignee: McCord Winn Textron Inc
Current assignee: McCord Winn Textron Inc
Priority date: 1999-02-05
Filing date: 2000-02-04
Publication date: 2000-08-10
Anticipated expiration: 2001-08-05

Abstract

A power inflation system, e.g. for use as an inflatable lumbar support for a seat, comprises a pump (22) in fluid communication, through a conduit (140A, 140B) with a closed cell (18). A sound attenuator (200) is operatively disposed in line in said conduit.

Description

PNEUMATIC SYSTEM SOUND ATTENUATOR

This invention relates generally to pneumatic systems, and more

particularly to sound attenuators for pneumatic systems. The invention has

particular utility in connection with power inflatable air cell pumping systems as

may be used, for example, for vehicle seats, and will be described in connection

with such utility, although other utilities are contemplated.

Some models of automotive vehicle seats are equipped with a pneumatic

lumbar support system which includes provision of one or more inflatable air

cells located in the lower region of the back rest or seat pan and an electric air

pump which, under the control of an operator switch, delivers low pressure air

to the cell. Such systems enable an occupant of a seat to adjust the firmness or

contour to meet his or her personal preference. Air cells may also be provided in

other regions of the seat, such as the side bolster areas.

While such air cell systems have enjoyed a certain level of consumer acceptance,

current air cell systems are quite noisy, typically generating noise levels (whistles

and blatts) of 60+ dba. Noise levels of 60+ dba or higher are particularly grating

to many consumers when present in the confined cabin space of a motor vehicle.

In accordance with the present invention, a sound attenuator is placed, in

line, between an air pump and air cell which significantly reduces noise being

transmitted from the pump to the air cell. For example, as employed in an

SUBSTITUTE SHEET (RULE ?6) automotive vehicle seat having seat and back rest portions and an inflatable air

cell, or cells, mounted within the seat, a low pressure non-reversible air pump is

provided having an internal working chamber with an air inlet and an air outlet

and a reciprocating diaphragm member driven by an electric motor within the

chamber between an intake stroke and an outtake stroke. The inlet and outlet

openings are fitted with valves that cooperate to allow air to be drawn into the

chamber through the inlet opening on the intake stroke and exhaust air from the

chamber through the outlet on the exhaust stroke. The outlet of the pump

communicates with the air cell of the system via a conduit, with a sound

attenuator being placed, in line, between the pump and the air cell.

These and other objects and advantages will be more readily apparent

when considered in connection with the following description and

accompanying drawings, wherein like numerals depict like parts, and wherein:

Figure 1 is a perspective view of a vehicle seat embodying the invention;

Figure 2 is a diagrammatic view of an exemplary embodiment of an air

pumping system incorporating the invention;

Figure 3 is an enlarged cross-sectional view of the system of Fig. 2;

Figure 4 is an enlarged fragmentary cross-sectional plan view taken along

lines 4-4 of Figure 3; Figure 5 is a fragmentary sectional view taken along lines 5-5 of Figure 4;

Figure 6 is an enlarged fragmentary sectional view taken along lines 6-6 of

Figure 4;

Figure 7 is an enlarged perspective view of a sound attenuator made in

accordance with the present invention; and

Figure 8 is an enlarged sectional view of another form of sound attenuator

according to the invention.

Referring now in greater detail to the drawings, Figure 1 illustrates an

automotive vehicle seat 10 incorporating the sound attenuator of the present

invention, and having a generally horizontal seat portion 12 and a back rest

portion 14 extending generally upwardly from the seat portion 12 to provide

support for an occupant in a seated position thereon. The seat 10 includes a

pumping system 16 for adjusting the contour and firmness of the seat in

accordance with the personal preference of the occupant.

An inflatable air cell 18 is mounted within the seat 10, preferably in the

lower lumbar region of the back rest portion 14, and includes an air fitting 20

(Figure 2) providing an opening into the interior of the air cell 18. While a single

air cell system is shown in the drawings for purposes of illustration, it is

understood that the invention contemplates within its scope seating systems employing multiple air cells in the same or different locations of the seat (e.g. the

lumber region, bolster region, seat pan, etc.).

As shown best in Figure 3, the system includes a non-reversible low

pressure diaphragm pump 22 for supplying air under low pressure (i.e. under 5

psi or 0.35 kg/cm²) to the air cell 18. The pump 22 has a rigid casing or pump

body 24 fabricated preferably of molded plastics material such as ABS. The body

24 includes a base portion 26 formed with a pair of U-shaped uprights 28, 30 that

cradle an electric motor 32. A cover 34 is attached to the base 26 and retains the

motor 32 in position on the uprights 28,30 and encloses a compartment 36

adjacent the motor 32 into which a rotary shaft 39 of the motor 32 extends.

A rigid manifold portion 38 is housed in the compartment 36 and includes

a continuous upstanding peripheral wall 40, that is generally cylindrical having

opposite open ends 42,44, the lower end of which is joined to the base 26 in such

manner as to provide an air-tight seal therebetween. An integrally formed

partition wall 46 divides the interior of the manifold into an upper working

chamber 48 and a lower chamber 50. The lower chamber 50 is further divided by

adjacent intake and exhaust cavity walls 52,54 extending in sealed relation

between the intermediate partition wall 46 at their upper ends and the base

portion 26 at their lower ends. The walls 52,54 thus isolate corresponding intake

and exhaust cavities 56,58 from the remainder of the lower chamber 50. An opening 60 is formed in the base portion 26 providing open flow

communication between the intake cavity 56 and the atmosphere external to the

pump body 24. The partition 46 of the manifold 38 is formed with a plurality of

air inlet openings 62 arranged concentrically about a central mounting hole 64

(Figure 4) providing air flow communication between the intake cavity 56 on one

side of the partition wall 46, and the working chamber 48 on the other side.

An inlet umbrella valve 66 is secured within the mounting hole 64 of the

partition wall 46 to selectively open and close the inlet openings 62 and thereby

control the introduction of air into the working chamber 48. As shown best in

Figure 5, the valve 66 comprises a generally T-shaped one piece member

fabricated of a resilient, pliable material such as rubber or plastics, and preferably

silicone. The valve 66 has a stem 68 that projects through the central mounting

hole 64 and is formed at its end with an enlarged locking head or bulb 70. The

head 70 is deformable, allowing it to be pulled through the mounting hole 64.

Upon exiting the hole 64, the head 70 returns to its enlarged state to confront the

edge of the hole 64 on the inlet cavity side of the partition wall 40.

An integrally formed annular sealing disc 72 is located at the other end of

the stem 68 within the working chamber 48 and extends radially outwardly in all

directions from the stem 68 across the working chamber side of the partition wall

40 to a peripheral outer edge radially beyond the outward periphery of the inlet

openings 62. The length of the stem 68 between the head 70 and underside of the disc 72 is slightly less than the thickness of the partition wall 46, such that the

stem is placed under constant tension, resiliently urging the flexible disc portion

72 releasably against an abutting underlying sealing surface 74 of the partition

wall 46, sealing off the inlet openings 62.

The partition wall 40 further has a plurality of outlet openings 76 arranged

circumferentially about a central mounting hole 78, like those of the inlet

openings 62, to provide air flow communication between the working chamber

48 and the exhaust cavity 54. An outlet umbrella valve 80 identical in

construction to that of inlet valve 66 is secured by its stem 82 within the

mounting hole 78, such that the enlarged head 86 at one end of the stem 82

projects into the working chamber 48 and the sealing disc 84 at the other end is

accommodated in the exhaust cavity 58 (the reverse of that of the inlet valve 66).

The sealing disc 84 is urged resiliently into releasable sealed engagement against

and underlying sealing surface 88 of the partition wall 46 on the exhaust cavity

side of the wall 46, closing off the outlet openings 76.

The pump 22 includes a flexible diaphragm 90 (Figure 3) that is mounted

on the manifold 38 and forms a moveable wall of the working chamber 48. The

diaphragm 90 is molded from a soft, resilient material, such as natural rubber,

and has a generally planar wall 92 that extends continuously across the upper

end 44 of the manifold 38. An integrally formed peripheral flange 94 of the

diaphragm 90 extends transversely from the wall 92 and encircles the outer wall or mouth 96 of the manifold 38. The flange 94 has an inner annular rib 98 that

interlocks with a corresponding external recess or step 102 of the manifold 38 to

secure the diaphragm 90 in position on the manifold 38 and provide an air-tight

seal therebetween.

The wall 92 of the diaphragm 90 is coupled by a rigid linkage 104 to an

eccentric crank 106 mounted on the rotary shaft 39 of the motor 32 for driving

the wall 92 of the diaphragm 90 with reciprocating to and from motion relative

to the manifold 38 to define chamber-expanding intake and chamber-contacting

exhaust strokes of the diaphragm 90. One end of the linkage 104 extends

through a central aperture 110 of the diaphragm wall 92 and is formed with a

pair of axially spaced locking heads 112, 114, which engage the wall 92 on

opposite sides of the aperture 110 to secure the linkage 104 axially relative to the

diaphragm 90. The other end of the linkage 104 is formed with a journal 116.

The crank 106 has a cylindrical collar portion 118 mounted concentrically

about the shaft 39 and an axially offset wrist pin 122 projecting from the collar

118 and received in the journal 116 to couple the crank 1016 and linkage 104.

The motor 32 is coupled to the vehicle's battery (not shown) by lead wires

124 through an electrical switch 126 (Figure 2). The switch 126 includes a switch

body or housing 128 adapted for mounting within the vehicle's interior

compartment at a location accessible and convenient to the operator, such as, for

example, the vehicle's door panel or center console. The housing 128 supports a control pad or button 130 that is biased by a spring (not shown) in the usual

manner to a neutral or "OFF" position to interrupt power from the battery to the

pumping system 16. In the present example, the control pad 130 comprises a

rocker element that is able to be depressed by the operator in order to move the

element 130 from the initial neutral position to one of two control positions, the

first of which closes the electrical circuit between the battery and motor, and the

second of which operates a bleed valve 132 to be described below.

Referring to Figures 3 an 5, energizing the motor 32 by moving the switch

element 130 to the first position causes the shaft 39 to rotate, which in turn

rotates the crank 106. The eccentric wrist pin 122 of the crank 106 transmits the

rotary motion of the crank 106 into axial reciprocating displacement of the

linkage 104, which in turn moves the wall 92 of the diaphragm 90 axially to and

fro relative to the manifold 38 between the air intake and exhaust strokes. On

each intake stroke, air is drawn into the working chamber 48 past the inlet valve

66 through the openings 62. A filter 134 can be accommodated within the intake

cavity 56 to cleanse the intake air of impurities. The sealing disk 84 of the outlet

umbrella valve 80 remains sealed on the intake stroke to prevent air from being

drawn in to the chamber 48 through the outlet openings 76.

On each exhaust stroke of the diaphragm 90, the inlet valve 66 closes

causing the air within the chamber 48 to compress and exert opening pressure on

the outlet valve 80. The increase in air pressure flexes the peripheral edges of the sealing disc 84 of the outlet umbrella valve 80 out of sealed engagement with the

wall 40, allowing the compressed air to exhaust from the chamber 48 through the

air outlet openings 76.

A tubular connector 136 projects form the base 26 of the pump body 24

and is in open flow communication with the exhaust cavity 58 (Figure 3). An

upstanding shroud or a guard 138 extends alongside the connector 136 to protect

it from damage during handling and shipping.

Referring also to Fig. 7, a feature and advantage of the present invention is

to significantly reduce noise levels of air being pumped from a pump into an air

cell. More particularly, in accordance with the present invention, an air line or

conduit 140 A is coupled at one end to connector 136 and connected as its

opposite end to the inlet fitting of a sound attenuator 200. Sound attenuator 200

comprises an elongate cylindrical hollow chamber including an inlet fitting 202

and an outlet fitting 204 for connection to conduits 140A and 140B, respectively.

Sound attenuator 200 may comprise a simple hollow expansion tank, or sound

attenuator 200 may include one or more internal baffles (not shown). In this

regard sound attenuator 200 is, in some respect, similar to an exhaust muffler as

may be found in an exhaust system for a conventional internal combustion

engine; however, the baffling typically is not necessary since adequate noise

attenuation typically is achieved at the flow rates and pressures involved by

simply providing an expansion volume in-line between the pump and the air cell. Preferably, the inlet and outlet fittings are offset from one another (see. Fig.

7).

The outlet fitting 204 of sound attenuator 200 is connected to one end of

an air line or conduit 140B, which conduit is connected at its opposite end to the

inlet fitting of the air cell 18. Air expelled from the pump 22 on each exhaust

stroke is routed through sound attenuator 200 into the interior of the air cell 18

through the air line 140. Operation of the pump 22 continues until the desired

air pressure and thus a corresponding seat contour is achieved (typically in the

range of about 1-3 psi or 0.07 to 0.21 kg/cm², with pressures of up to 5 psi or 0.35

kg/cm² contemplated).

When the desired air cell pressure is attained, the operator simply releases

the control pad 130 which self-returns under spring force to the "OFF" position

to interrupt the flow of power to the pump 22. Halting operation of the pump 22

stops the flow of exhaust air which, in turn, causes the outlet umbrella valve 80

to close, thereby sealing the air cell 18 against air leakage back through the pump

22.

Once the pump 22 has been stopped, further pressurization of the cell 18

may be achieved by simply activating the control pad 130 to operate the pump 22

as before. The pump 22 is advantageously fitted with a small amperage hobby-

type motor 32 in order to minimize the size, weight, and energy requirement of

the system 16. An electric pump that draws about 500 milliamps is preferred, which is considerably less than that typically employed in the industry for

lumbar seating systems which draw about 2 Vi amps. Because of its small size,

however, the motor 32 may have some difficulty unseating the disc 894 of the

outlet valve 80 due to the back pressure acting on the disc from the air cell 18.

The greatest difficulty is encountered when the pump 22 commences operation

near the end of its exhaust stroke. To alleviate the problem and accommodate

the small amperage motor 32, it is preferred that a small breather hole 144 be

formed in the pump body 24 venting the working chamber 48 to atmosphere.

The hole 144 is extremely small (on the order of about 0.012 inches or 0.03048 cm

in diameter) and as such has little impact on the normal pumping operation of

the pump 22. However, during the initial startup, any pressure that builds in the

working chamber 48 by an incomplete exhaust stroke that is insufficient to crack

the outlet valve 80 is able to be vented to atmosphere through the hole 144. The

diaphragm 90 may then complete a full intake stroke followed by a full exhaust

stroke in order to generate sufficient momentum and pressure to unseat the

outlet valve 80.

When it is desired to relieve the air cell 18 of the air pressure, the operator

simply moves the control pad 130 to the second position to actuate the bleed

valve 132. As illustrated in Figure 1, the air line 140B has a main section

extending between the sound attenuator 200 and air cell 18, and a branched

section 148 off the main section 140B closed at its end by the bleed valve 132. The bleed valve comprises a solenoid valve 132a that is wired to the switch 126 and

maintained normally in the closed position until the control pad 130 is moved to

the second position. Figure 5 shows an alternative bleed valve arrangement

comprising a mechanical relief valve 132b, such as a Schrader-type valve,

preferably incorporated into the construction of the switch 126. Rocking the

control pad 130 to the second position acts to unseat an axially movable stem of

the valve and thereby open the air line to atmosphere. Releasing the control pad

132 allows the stem, which is spring-biased to the closed position, to reseat itself

to seal the air line.

The advantages of the present invention will be demonstrated from the

following working example. For the purposes of this example, a pneumatic

lumbar support system was inflated to 2.3 psi (or 0.162 kg/ cm²⁾ with a 25

kilogram load. Sound was measured in a sound box using JCPS standard

calibrated test methods as described in JCPS (Jaguar Specification) 10-29. The

production system was then modified by cutting the conduit leading from the air

pump to the bladder, and inserting a sound attenuator made in accordance with

the present invention. The sound attenuator comprised a 1.87 (or 4.75 cm) inch

long by 1.36 inch (3.45 cm) diameter hollow cylinder formed of ABS sealed at

both ends, with an inlet fitting located at one end and an outlet fitting located at

the other end, and radially offset from one another by 90°. The bladder was then pressurized as before, and sound measurements again made using the JCPS test

method, and the results recorded and set forth in the following table.

*dba

As can be seen from the foregoing, the incorporation of a sound attenuator

in accordance with the present invention results in a significant reduction in

noise level.

The invention is susceptible to modification. For example, as seen in Fig.

8, the sound attenuator may take other forms. For example, the sound attenuator

may comprise a rectangular or cubed shaped container 206 having an inlet 208

communicating with the interior of the chamber 209, with an internal baffle or

chamber 210 which in turn communicates with an outlet 212 through an opening

214 formed in a wall of the internal chamber 210. Also, the sound attenuator

may comprise an expandable bladder, formed of a resiliently deformable

material, which may be restrained within a cage or the like against expansion

beyond a predetermined volume. While the invention has been described in connection with an inflatable

air cell for use with a pneumatic lumbar support system for a seat, it should be

appreciated that the invention also advantageously may be used to reduce sound

in other pneumatic pumping systems in which noise may be a problem such as

for inflatable beds or other home furnishings, airplane seating, and other forms

of closed pneumatic actuated closed systems such as cells and pistons for various

applications.

Claims

1. A power inflation system comprising a pump 22 in fluid

communication, through a conduit 140A, 140B, with a remote flexible wall,

expandable closed cell 18, and a sound attenuator 200 operatively disposed in

line in said conduit.

2. An inflatable system according to claim 1, wherein said sound

attenuator 200 comprises a hollow chamber.

3. An inflatable system according to claim 2, wherein said hollow

chamber 200 comprises a hollow cylinder.

4. An inflatable system according to claim 2, wherein said hollow

cylinder 200 includes an inlet 202 formed in one end, and an outlet 204 formed in

the other end, wherein said inlet and outlet are radially offset from one another.

5. An inflatable system according to claim 1, wherein said inflatable

cell 18 comprises an inflatable air cell.

6. An inflatable system according to claim 1, wherein said inflatable

cell 18 comprises an air cell, and further comprising a valve 132 for selectively

relieving pressure from said cell.

7. An inflatable system according to claim 1, wherein said pump 22

comprises an electrically driven air pump 32.

8. A power inflatable seating support system comprising a pump 22

in fluid communication, through a conduit 140A, 140B, with a remote flexible wall, expandable closed air cell 18, and a sound attenuator 200 operatively

disposed in line in said conduit.

9. An inflatable system according to claim 8, wherein said sound

attenuator 200 comprises a hollow chamber.

10. An inflatable system according to claim 9, wherein said hollow

chamber 200 comprises a hollow cylinder.

11. An inflatable system according to claim 9, wherein said hollow

12. An inflatable system according to claim 8, further comprising a

valve 132 for selectively relieving pressure from said cell.

13. An inflatable system according to claim 8, wherein said pump 22

comprises an electrically driven air pump 32.