U.S. patent number 3,789,843 [Application Number 05/228,529] was granted by the patent office on 1974-02-05 for breath-actuated aerosol dispenser.
This patent grant is currently assigned to Armstrong-Kropp Development Corporation. Invention is credited to John C. Armstrong, George F. Lyman.
United States Patent |
3,789,843 |
Armstrong , et al. |
February 5, 1974 |
BREATH-ACTUATED AEROSOL DISPENSER
Abstract
An inhalation device for use with an aerosol container capable
of discharging a metered amount of an aerosol formulation on
depression of its valve nozzle comprising, a chamber, a mouthpiece
communicating with the chamber, a mechanism for causing actuation
of the valve including a movable wall, a linking lever, an
actuating lever, a spring biasing the actuating lever, and a latch
mechanism such that the movable wall member disposed between an air
admission port into said chamber and said mouthpiece moves away
from said port under influence of air flow through said port to
release the latch mechanism when suction is applied to said
mouthpiece and therefore causing the actuating lever to actuate the
valve.
Inventors: |
Armstrong; John C. (Milton,
MA), Lyman; George F. (Weston, MA) |
Assignee: |
Armstrong-Kropp Development
Corporation (West Roxbury, MA)
|
Family
ID: |
9796414 |
Appl.
No.: |
05/228,529 |
Filed: |
February 23, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Feb 25, 1971 [GB] |
|
|
5,450/71 |
|
Current U.S.
Class: |
128/200.23 |
Current CPC
Class: |
A61M
15/0091 (20130101); A61M 15/009 (20130101) |
Current International
Class: |
A61M
15/00 (20060101); A61m 011/00 () |
Field of
Search: |
;128/173,208,213,222,172.2,185,187,272 ;206/41,46R,46M |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Recla; Henry J.
Attorney, Agent or Firm: Dike, Bronstein, Roberts &
Cushman
Claims
1. An inhalation device for use with an aerosol container capable
of discharging a metered amount of an aerosol formulation on
depression of its valve nozzle, said device comprising a chamber, a
mouthpiece communicating with said chamber, spring means for
causing actuation of said valve, latch means for maintaining the
device in a cocked position ready for discharge, and triggering
means responsive to suction applied to said mouthpiece, said
triggering means including a movable wall member pivotally mounted
internally of said chamber between an air-admission port means into
said chamber and said mouthpiece, said movable wall member adapted
to move away from said port means under the influence of ambient
air pressure applied to one side of said wall through said port
means when suction is applied to said chamber through said
mouthpiece and by so moving to release said latch means, wherein
said air-admission port means comprises an aperture in a wall of
said chamber and said movable wall means includes a button means
substantially filling said aperture when the
2. An inhalation device as claimed in claim 1 wherein the clearance
between the sides of said movable wall portion and the walls of
said chamber is substantially less when the device is in its cocked
position than when in
3. An inhalation device as claimed in claim 1 wherein said spring
means biases said movable wall member toward said port when the
device is in its
4. An inhalation device as claimed in claim 1 wherein separate
biasing spring means are provided to bias said movable wall member
toward said
5. An inhalation device as claimed in claim 1 wherein said device
includes a second chamber for receiving and retaining said aerosol
container and said device is provided with a sliding cover for said
second chamber, said cover including a wedge member movable
relative thereto, said wedge member adapted to press against the
end of said container to retain said container in a fixed position
in said second chamber when said cover is closed.
Description
BRIEF SUMMARY OF THE INVENTION
This invention relates to an inhalation-actuated aerosol dispenser
of the type disclosed and claimed in Kropp U.S. Pat. No. 3,636,949,
dated Jan. 25, 1972.
Aerosol pharmaceuticals still constitute a relatively minor unit
volume in the aerosol field. In the period from 1950 to 1960, there
was considerable enthusiasm about the future growth of aerosol
pharmaceuticals, but by the early 1960's, it was apparent that the
market for aerosol pharmaceuticals had not developed as some had
predicted.
Much of the early optimism about this future market size developed
as a result of the potential for inhalation aerosols, especially
bronchodilators. This was based on the enormous advantage that the
modern aerosol package brought into inhalation therapy, in contrast
to the earlier crude nebulizers.
These advantages are:
1. Uniform dosage with metering valves;
2. Uniform particle size of the medicinal preparation;
3. Greatly improved product stability and elimination of outside
contamination by virtue of the hermetically sealed aerosol;
4. Inexpensive, compact dispensing containers. In contrast to
orally delivered medication, inhalation aerosols have these
outstanding advantages:
1. Infinitely more rapid relief through absorption in the bronchi
and pulmonary areas. In this respect, aerosol inhalation can often
be considered equivalent to injection;
2. Lower dosage levels of medicament are possible due to its
delivery to the site of the broncho-spasm. This is usually due to
the absence of loss in the intestinal tract;
3. Elimination of gastro-intestinal side effects. With these
advantages generated by aerosol technology, the early optimism is
not surprising.
Aerosol inhalation therapy, however, at least in the United States,
has failed to meet the expected growth pattern. Perhaps the drug
industry has needed a decade to become aerosol oriented and accept
this new delivery system before expanding into new opportunities
involving inhalation aerosols.
The most significant problem associated with inhalation aerosols
has been the difficulty for many patients to coordinate the manual
release of the medication with the initiation of inspiratory
effort. Indeed, many people not afflicted with asthma, bronchitis,
emphysema, or other respiratory difficulties have demonstrated that
they are unable to coordinate these tasks properly. Patients
suffering from the distress of broncho-restriction may have much
greater difficulty. In addition, synchronization is difficult for
both children and elderly patients. These are two important groups
who could benefit from aerosol bronchodilators if coordination were
not a problem.
A second and related problem lies in the fact that even though the
aerosol metering valve delivers a predetermined dosage of aerosol
medicament time it is depressed, the valve can be depressed
repeatedly. Thus, if the patient's coordination with his breathing
is off and the desired relief is not obtained, he has a tendency to
press the valve again and again. This possibility of an
unintentional excess dosage delivered to the region of the mouth
and upper throat rather than to the bronchi and pulmonary areas as
desired has somewhat restricted the range of medicaments packaged
in aerosol form.
Very recently, these problems have been alleviated with the
development of breath-actuated aerosol dispensing devices such as
the one disclosed in the aforesaid Kropp patent. Sometimes these
are referred to as inhalation-initiated aerosols or more simply
"demand valves." Very simply, the demand valve eliminates the need
for manual coordination by actuating automatically when the patient
inhales with his lips in contact with a mouthpiece. Only a very
slight negative pressure is required to trip the simple mechanism
which actuates the metering valve. In addition the demand valve
must be reset before the metering valve may be discharged again.
One of the important features of this development is that it in no
way changes the dosage or packaging components previously in use
insofar as the refill aerosol is concerned. The same metering
valve, container body (glass, metal or plastic), medicament, and
propellant system may be used. No changes are required in the
filling and packaging lines with the exception of final assembly
and the insertion of the demand valve itself. The unit is easy to
use and compact.
One such device is described and claimed in the aforesaid patent.
This comprises a walled chamber provided with a mouthpiece and with
an air access port remote from the mouthpiece. The air access port
is at least substantially filled with a movable wall portion
designed to move toward the interior of the chamber when air is
removed from the chamber through the mouthpiece as by a person
inhaling with the mouthpiece in his mouth. Means are provided to
retain an aerosol container in a fixed position with the metering
valve of the aerosol container located within the chamber in a
position to discharge aerosol compound through the mouthpiece. The
actuating mechanism consists of the movable wall portion; a linking
lever having a latch means, which lever is pivotally mounted in the
chamber to move about its pivot responsive to the movement of the
wall portion; an actuating lever with a catch means adapted to
cooperate with the latch means on the linking lever pivotally
mounted in the chamber, said actuating lever having a portion
adapted to press against the metering valve of the aerosol
container and spring means to bias said wall portion and said
linking lever toward an initial portion wherein the latch means of
the linking lever may engage the catch means of the actuating
member and to move the actuating lever toward pressing engagement
with the metering valve. Finally, there is a resetting means such
as a strap associated with the actuating mechanism passing to the
outside of the chamber adapted when pulled to move the actuating
lever against the force of the spring away from engaging contact
with the metering valve and to bring the catch of the actuating
lever into contact with the latch of the linking lever and an air
valve means associated with the actuating mechanism adapted to
admit outside air freely from a position remote from the mouthpiece
relative to the metering valve when the actuating mechanism is
triggered.
The operation is very simple. To cock the device one pulls on the
resetting means. This pulls the actuating lever away from the
metering valve to a position where the latch of the actuating lever
can engage the catch of the linking lever. At the same time the
movable wall portion is biased toward an initial position pivoting
the linking lever so that its latch may engage the catch. When the
latch and the catch are engaged the device is cocked.
To trigger the device all one need do is to place the mouthpiece in
his mouth and inhale. Upon reduction of pressure within the chamber
the movable wall portion moves inwardly. This rotates the linking
lever about its pivot removing the catch from engagement with the
latch of the actuating lever. As soon as this happens the spring
moves the actuating lever into contact with the metering valve
which in turn discharges the metered amount of aerosol compound
through the mouthpiece. Simultaneously the air valve is opened
admitting a scavenging flow of air into the chamber from a position
behind the metering valve relative to the mouthpiece permitting the
person to complete his inhalation cycle freely and completely. At
the same time, since the rush of air comes in behind the metered
aerosol discharge of medicament, forces that medicament into the
bronchi and pulmonary areas as is desired.
The device described in the aforesaid Kropp patent has proven to be
a very practical, useful, effective and relatively inexpensive
device. However, a number of changes have been made during the
course of the development toward commercialization of this device,
as a result of extensive testing, without, however, any substantial
change in the essential mechanism as described above.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevation partially in section of a first version of
the improved device of the present invention at the moment of
actuation taken along line 1--1 of FIG. 3;
FIG. 2 is an elevation partially in section corresponding to FIG. 1
but with the device in its cocked and locked position;
FIG. 3 is a top view of the device of FIGS. 1 and 2;
FIG. 4 is a section along line 4--4 of FIG. 1;
FIG. 5 is a rear view of the device of FIGS. 1 and 2;
FIG. 6 is an elevation partially in section of a second version of
the improved device in its cocked and locked position;
FIG. 7 is an elevation in section of the device of FIG. 6 at the
moment of actuation;
FIG. 8 is a front view of the device of FIGS. 6 and 7;
FIG. 9 is a rear view of the device of FIGS. 6 and 7;
FIG. 10 is a top view of the device of FIGS. 6 and 7;
FIG. 11 is a section along line 11--11 of FIG. 6;
FIG. 12 is a detail of the leaf spring and linking lever of the
device of FIGS. 6 and 7; and
FIG. 13 is a partial elevation showing a second version of the
sliding cover.
DETAILED DESCRIPTION
The first version of the improved device of the present invention
is shown in FIGS. 1 to 5. The aerosol dispenser or demand valve,
indicated generally at 21, is a generally rectangular box-like
structure slightly larger than, but substantially the same size as,
a pack of king-size cigarettes, molded from a rigid thermoplastic
material such as high-impact polystyrene, in two symmetrical halves
indicated at 22 and 23, joined together. Demand valve 21 is
provided with a front wall portion 24, a rear wall portion 25, a
right side 26, a left side 27, a top 28, and a bottom 29. A
forwardly extending portion 31 near the bottom of front wall
portion 24 together with a corresponding extension at the bottom of
right side 26, left side 27 and bottom 29, forms a mouthpiece 32
with a substantially rectangular aperture 33 of convenient size to
be held between a person's lips. An internal wall 34 having a
generally vertical portion 35 and a horizontal portion 36 divides
the interior of demand valve 21 into two chambers, an
aerosol-receiving chamber 37 and an operating chamber 38. Internal
wall 34 is continuous except for aperture 39 provided in horizontal
portion 36 at the bottom of aerosol container-receiving chamber 37
to receive the valve nozzle portion 39 of an aerosol container 43
within operating chamber 38. Rear wall portion 25 is provided with
a plurality of horizontal air-admitting apertures or ports 41,
which when the mouthpiece 32 is held in a person's mouth provides
the only important access for entry of air into operating chamber
38. Walls 24, 34 and portions of walls 28 and 29 are provided with
an internal groove in left half 32 (the half shown in FIGS. 1 and
2) and a corresponding tongue in right half 23, to facilitate the
matching of the two halves and to provide an airlock along the line
of juncture.
A standard medicament aerosol container is indicated at 43. Such
containers are provided in glass, metal or plastic (a typical glass
container is shown) and while there are some minor structural
differences between the three, all three are made to a standard
size and all conventionally have a container body 44 with a neck
portion 45, a cap 46, a cylindrical extension 47 on cap 46, a valve
stem 48 and a nozzle 49. Nozzle portion 49 is generally rectangular
in cross-section with flat parallel sides. The standard such
container is designed to be operated in the inverted or valve-down
position and to expell upon pressure a measured amount of a mixture
of propellant and medicament horizontally from nozzle 49 each time
nozzle 49 is pressed toward container 44. Aerosol
container-receiving chamber 37 is of a size to receive the standard
aerosol container 43 with the shoulder of cap 46 resting against
the top of horizontal wall portion 36 and with cylindrical
extension 47, valve stem 48, and nozzle portion 49 extending into
operating chamber 38 through aperture 39 with outlet 50 of nozzle
portion 49 adjacent to and substantially at the center of
mouthpiece aperture 33. Guiding slots 52 and 53 are provided on the
inside of side walls 26 and 27, both to insure the proper entry of
container 43 into chamber 37 and to minimize the width of demand
valve 21.
Chamber 37 is provided with a cover portion 54 pivotally mounted as
indicated at 55 at one end between the side walls at a point
adjacent internal wall 34. The other end of cover portion 54 is
provided with a forwardly extending finger grip 56 which extends
through a recess provided therefor at the top of front wall 24. At
each side of grip 56 a series of interlocking ridges, indicated at
57, are provided both on the forward end of cover 54 and the inside
of front wall 24, to retain cover 54 in place. The bottom of cover
54 is provided with an upstanding bead 58 adapted to press against
the bottom of container 43. With cover 54 raised container 43 can
easily be introduced into or removed from container-receiving
chamber 37. When cover 54 is locked into position by interlocking
ridges 57 by pressure on its top, container 43 is retained in
chamber 37.
The actuating mechanism is substantially identical to that
disclosed and claimed in the aforesaid U.S. Pat. No. 3,636,949, and
comprises a movable wall portion 61, a linking lever 62, an
actuating lever 63 and a spring 64. Such modifications as have been
made were made for ease and reliability of manufacture, and ease
and reliability of assembly. It will be noted as explained below
that there are only five parts other than the two shell halves 22
and 23; that there are no sub-assemblies except to link one end of
spring 64 to actuating lever 63, and all of the parts except for
spring 64, the other end of which is slipped over a post 80
provided therefor between the two shell halves, are pivotally
mounted between opposed sockets provided in the two shell halves,
so that the entire assembly can be put together very rapidly and
very easily.
Movable wall portion 61 is a flat plate that substantially fills
all of the interior space inside rear wall 25. It is pivotally
mounted at the bottom by a pair of studs 65, one of which is
provided on each side and each of which is adapted to fit into a
socket 70 provided therefor in side walls 26 and 27. A raised
portion 66 is provided on the interior side thereof to provide a
bearing surface for one end of linking lever 62.
Linking lever 62 is provided at an intermediate portion with a pair
of opposed studs 67 adapted to fit into sockets (not shown)
provided therefor on the inner walls of sides 26 and 27 to act when
assembled as a pivot. A centrally disposed elongated arm portion 68
is provided above studs 67 and a relatively short blade portion 69
is provided below studs 67. Arm portion 68 is provided on one side
at its end with a rounded knob portion 71 adapted to ride against
raised portion 66 of movable wall 61. The lower end of blade
portion 69 is provided with a flat surface 72 which acts as the
catch. Surface 72 is tapered slightly so that the edge closest to
actuating lever 63 is slightly closer to stud 67 than is the edge
away from the actuating lever 63. The back of arm portion 68 is
provided with a rounded raised portion 73 at a position slightly
above pivot 62 adapted to rest against spring 64 and thereby to
bias knob 71 and correspondingly movable wall 61 toward rear wall
25.
Actuating lever 63, resetting strap 74 and mouthpiece cover 75 are
injection molded as a one-piece assembly. Actuating lever 63 is
provided at one end with a pair of opposed studs 76 adapted to fit
into a pair of sockets (not shown) provided therefor on the inside
of side walls 26 and 27 to provide a pivot mounting. The body of
lever 63 is formed as an inverted saddle with two side walls 77
adapted when demand valve 21 is assembled and aerosol container 43
is in place therein, to overlie closely on each side the flat sides
of nozzle portion 49. Side walls 77 are connected by bottom wall
78. Bottom wall 78 is formed, adjacent pivot 76, in an inverted
V-shape providing on the top thereof a relatively sharp edge 79
adapted to press against the end of nozzle 49. At a point remote
from pivot 76 beyond the location of nozzle 49, there is provided a
web portion 81 between side walls 77 of actuating lever 63. Beyond
web portion 81, a bottom wall 78 is thickened slightly as a
strengthening measure and terminates in a generally cylindrical
portion 82 which is separated from side walls 77 and is adapted to
receive a loop at one end of coil spring 64. The loop at the other
end of spring 64 passes around mounting post 80 provided between
side walls 26 and 27 adjacent top 28. The arrangement of the parts
is such that the side of spring 64 presses against rounded portion
73 of linking lever 62 as the demand valve is being cocked to bias
movable wall portion 61 toward rear wall 25.
Side walls 77 of actuating lever 63 extend beyond the location of
spring 64 passing therebetween and a notch 83 is provided at the
intersection of the top of each side wall 77 with that end of each
side wall 77 remote from pivots 76. The two aforesaid notches are
adapted to engage surface 72 of blade portion 69 of linking lever
62 to act as a latch.
Resetting strap 74 extends from cylindrical portion 82 beyond the
location of the end of the spring 64 through a slot 84 provided
therefor in bottom wall 29. A groove 85 is provided on the bottom
or back side of strap 74 at a position adjacent the outside of
bottom wall 29 when the device is in its cocked position to act as
a bend line. Strap 74 terminates in mouthpiece cover portion 75
adapted to cover aperture 33 of mouthpiece 32. A second groove or
thinned portion 86 is provided at the intersection of strap 74 and
cover portion 75 also to act as a bend line. The length of 74 is
such that when cover portion 75 is in place over mouthpiece 32 the
latch of actuating lever 63 is slightly removed from the catch of
linking lever 62 as shown in FIG. 2 so that no movement of movable
wall 61, while the device is in the storage position can uncock the
device. The release of cover 75 from mouthpiece 32 permits the
catch to re-engage the latch under the force of spring 64 placing
the device in condition for instant use.
The upper end of cover portion 75 is provided with an inward
extension 87 having a groove 88 adapted to engage a ridge 89
provided on the upper outer end of upper wall 31 of mouthpiece 32.
A ridge 91 is provided across a midpoint on the inside of cover
piece 75 of an extent substantially equal to the width of aperture
33 to insure that cover 75 will cover mouthpiece 32 when in
position.
As pointed out above the release of cover 75 from mouthpiece 32
permits the catch and latch to engage and further permits the
mouthpiece to be placed in a person's mouth as indicated in FIG. 1.
Upon the inhalation by that person the pressure is reduced within
operating chamber 38 creating a pressure differential between the
side of movable wall portion 61 adjacent air-admitting ports 41 in
rear wall 25 and the side facing chamber 38. As soon as the
pressure differential is sufficient to overcome the biasing force
imposed upon linking lever 62 by contact between the side of spring
64 and rounded portion 73 on the rear of linking lever 62, movable
wall portion 61 pivots about pivot 65 causing the linking lever 62
to pivot about pivots 67, releasing the latch at the lower end of
linking lever 62 from the catch at the outer end of actuating lever
63. As soon as this happens spring 64 is permitted to retract,
forcing sharp edge 79 on bottom 78 of actuating lever 63 against
the end of nozzle 49 of aerosol container 43, causing aerosol
container 43 to discharge a metered discharge through aperture 53
of mouthpiece 32 into the mouth of the person. The instant of
discharge is shown in FIG. 1.
Valve means for admitting outside air into operating chamber 38 at
the instant of discharge to eliminate the reduced pressure within
chamber 38 permitting the person to complete his inhalation cycle
and acting as a scavenger to force the discharge deep into the
bronchi and pulmonary regions is provided by providing the upper
portion of the side walls 26 and 27 with a pair of recesses 92 and
93, which recesses extend across top wall 28 as indicated at 94 at
a position behind the location of movable wall portion 61 when in
its cocked position next to rear wall 25 as in FIG. 2 but at the
position assumed by the upper end of movable wall portion 61
between discharge as shown in FIG. 1.
Since movable wall portion 61 substantially fills the cross-section
of operating chamber 38 when the wall portion is in its cocked
position adjacent rear wall 25, very little air is admitted into
chamber 38 during the initial part of the person's inhalation
cycle. It has been determined that some air leakage into chamber 38
is desirable since this prevents the device from being actuated by
a mere sucking action and requires that there be an actual
inhalation into the lungs. In addition either this leakage or the
fact that the movable wall portion is pivotally mounted at one end
or both increases both the sensitivity and the reproducibility of
operation of the device. As soon as the device triggers movable
wall portion 61 pivots to a position where it is surrounded at its
upper end by recesses 92, 93 and 94 which in the actual device
measure about 11/2, 11/2and 1 in. long respectively by
one-sixteenth in. in depth. This additional opening of one-fourth
square inch is approximately the same in area as the aperture shown
in the embodiments shown in U.S. Pat. No. 3,636,949 and therefore
permits the instantaneous ingress of approximately an equal amount
of outside air.
The device is reset by pulling on strap 74, which pulls down
actuating lever 63 against the force of spring 64 permitting the
catch of linking lever 62 to engage the latch of actuating lever
63. At the same time contact between spring 64 and rounded portion
73 of linking lever 62 biases the movable wall portion 61 toward
rear wall 25.
The embodiment of demand valve 21 shown in FIGS. 1 to 5 has been
subjected to a very extensive testing program under field
conditions. As a result of this testing a number of refinements
were made, resulting in the embodiment shown in FIGS. 6 to 13
wherein as to most of the parts which remain unchanged the same
numbers are assigned as in FIGS. 1 to 5.
Referring to FIGS. 6 to 13, the overall shape of demand valve 21
has been modified slightly to conform better to the shape of the
hand. Thus since the width of the hand at the location of the
little finger is less than the width of the hand at the location of
the first three fingers, the bottom of rear wall 25 has been
rounded in slightly with movable wall 61 shaped to conform. So also
side walls 26 and 27 have been rounded in correspondingly adjacent
their intersection with bottom portion 29. In addition the forward
ends of side walls 26 and 27 have been rounded in adjacent their
junction with front wall 24 to better conform to the typical shape
of a bent thumb. As pointed out above, these changes in shape make
demand valve 21 easier and more comfortable to hold as well as
making the overall appearance aesthetically more pleasing.
As far as rear wall 25 is concerned, it was discovered on field
testing that there were two deficiencies. One was that the
plurality of air-admitting ports 41 tended to pick up dust, dirt
and lint from the inside of pockets and pocketbooks, and provided
to be difficult to clean. In addition there were a number of people
who felt the need of a panic button--something that they could push
to trigger the device, if, for example, they were in the midst of
an asthma attack. As a result, it was decided to provide a single
round aperture 101 as the air-admitting port. A matching button 102
is provided on the face of movable wall portion 61. Button 102 is
provided with an upstanding peripheral wall portion 103 designed to
fit closely against shoulder 104 provided around the periphery of
aperture 101. Button 102 is provided with a depressed central panel
105 in order to avoid the possibility that the device could be
triggered inadvertently because of accidental contact between the
side of a finger and button 102. The close contact between shoulder
104 of aperture 101 and the peripheral wall portion 103 effectively
keeps dirt out of space between movable wall portion 61 and the
inner sides of rear wall 25. The area of aperture 101 is such (the
diameter is about eleven-sixteenth inch) that upon a slight
reduction of pressure within operating chamber 38 wall portion 103
moves slightly away from shoulder 104 admitting outside air to the
entire back side of movable wall portion 61.
One unexpected development was that there turned out to be a wide
variation in the force required to actuate various metering valves.
This variation is not very critical when such valves are actuated
manually since a person's thumb can develop a substantial amount of
force. It becomes quite critical, however, when the force is
applied by a spring attached to a lever arm, since if the designed
force applied is insufficient, it can be increased only by
increasing the mechanical ratio of the lever arm or increasing the
strength of the spring. A change in the ratio of the lever arm is
impractical since this because of space limitations would require a
complete redesign of the entire demand valve housing. On the other
hand, a change in the strength of the spring necessarily changes
the biasing force of the spring against linking lever 62, thereby
changing the actuating pressure differential. Of course the desired
actuating pressure differential could be re-established by changing
the internal geometry either by moving the location of mounting
post 80 or by changing the shape of rounded raised portion 73 on
linking lever 62, or both. On the other hand, it was deemed
undesirable to provide all of the demand valves 21 with a spring of
increased strength merely to accommodate that small percentage of
metering valves which require an excessively high operating
pressure, or in the alternative, to provide a number of different
models of the demand valve differing only in the location of
mounting post 80 and/or the shape of linking lever 62.
It was decided therefore to eliminate raised portion 73 from the
back of linking lever 62 and to re-locate mounting post 80 so that
spring 64 would at all times be free of contact with linking lever
62. At the same time a separate biasing spring 107 was provided to
bias linking lever 62 and correspondingly movable wall portion 61
toward the cocked position. This is shown in detail in FIG. 12.
Spring 107 is provided with a generally rectangular slot 108
arranged axially internally thereof in the upper portion for the
passage of elongated arm portion 68 of linking lever 62
therethrough. A notch 109 is provided on the front face of
elongated arm portion 68 to receive the upper end of spring 107.
Leaf spring 107, which is substantially of the same width as blade
portion 69, extends around elongated arm portion 68 behind pivot
studs 67 and terminates in front of a mounting stud 110 provided
therefor between sides 25 and 26 just in front of and above pivots
65. An additional advantage of the separation of the actuating
function of spring 64 from the biasing function is that as soon as
the internal pressure within operating chamber 38 returns to normal
after the actuation of demand valve 21 movable wall portion 61
returns to its normal position in contact with the inner side of
rear wall portion 25 under the influence of biasing spring 107 as
indicated in FIG. 7.
Another problem that developed was that it was possible to insert
aerosol container 43 so that outlet 50 of nozzle portion 49 was
facing in the wrong direction so that upon actuation the discharge
was directed toward the interior of operating chamber 38 rather
than through mouthpiece 32 as described. This possibility has been
eliminated by providing the rear of nozzle portion 49 with an
outstanding boss 112 and aperture 39 with a corresponding slot 113.
If boss 112 is aligned with slot 113 as container 43 is inserted
into bottle-receiving chamber 37, nozzle portion 49 will pass into
operating chamber 38 as desired. Unless the boss and the slot are
aligned, container 43 cannot be inserted completely into
bottle-receiving chamber 37.
There have been a number of design changes in actuating lever 63.
Side walls 77 have been extended to more completely surround the
sides of nozzle portion 49. The sharp edge 79 on the inside of
bottom 78 has been replaced by a rounded portion 115 to provide a
better bearing surface against nozzle 49. The details of the
mounting of integral strap 74 and of the lower end of spring 64
have been changed for increased strength. Strap 74 now extends the
full width of bottom 78 and the lower end of spring 64 is now
mounted in a metal pin 116 that passes between apertures provided
for that purpose in side walls 77 in the portion behind web 81.
Reinforcing members 117 may be provided on the inside of side walls
77 to further reinforce and strengthen pin 116 and side walls
77.
While the volume of air admitted through air-admission ports 92, 93
and 94 was sufficient, there was some who believed that there was
an advantage in admitting outside air into operating chamber 38
upon the triggering of demand valve 71 from a position just behind
nozzle 49. Accordingly in the embodiment shown in FIGS. 6 to 13 the
air-admission port has been re-established as an aperture 121 in
bottom wall 29, which aperture is closed off when the device is in
its cocked position by resilient foam pad 122 formed of a material
such as a closed-cell neoprene foam adhesively mounted to bottom 78
of actuating lever 63. Aperture 121 is substantially square-shaped
with a dimension of about one-fourth inch more or less on each
side.
Finally the design of cover portion 54 was such that it proved
difficult to manufacture in that its proper operation depended upon
the maintenance of precise dimensions in three separately molded
parts--cover portion 54, right half 22 and left half 23. If the
distance between the effective center of pivot 55 and interlocked
ridges 57 in cover portion 54 increases relative with the
corresponding distances in the shell of demand valve 21, the cover
becomes difficult to press into position. On the other hand, if
this distance in cover portion 54 decreases relative to the
corresponding distance in the shell, the cover won't lock at all.
In any event, the interlocking ridges 57 tend to wear down with
use. All in all the arrangement proved to be intolerant of normal
manufacturing tolerances.
In place thereof a sliding cover 125 has been provided that extends
over the entire top of demand valve 21. To accomplish this side
walls 26 and 27 and front wall 24 are extended above top wall 28
and a horizontal groove 126 is provided on the inside thereof to
receive tongue 127 on cover 125. A depressed panel 128 is provided
on the top and near the rear of cover 125 to act as a finger grip.
The underside of cover 125 is provided with a sliding wedge 129
designed to wedge against the top of aerosol container 43 to hold
it in place with cap 46 pressed against internal wall 36. Sliding
wedge 129 has a transverse web portion 131 designed to ride in
groove 126 beneath cover 125, a depending wedge portion 132 that
tapers rearwardly downwardly and an upstanding boss 133 adapted to
ride in a groove 134 provided axially therefor in the underside of
cover 125. In one version the top of tongue 133 and the bottom of
groove 134 are provided with interlocking V-shaped notches 135. In
this version a second groove 136 is provided on the underside of
cover 125 to engage knob 137 provided on top of web 131 of sliding
wedge portion 129. This knob and second groove limits the travel of
wedge portion 129 relative to cover 125.
Rear wall portion 25 is provided with a portion 138 which extends
above top wall 28 sufficiently to permit clearance between top wall
28 and the bottom of sliding wedge 129 and to act as an abutment
for the rear of sliding wedge 129 while permitting cover 125 to
pass. Thus as cover 125 is slid back, the rear of wedge 129 is
forced against abutment 138 which pushes wedge 129 toward the
forward edge of cover 125 where its further movement is prevented
by grooves 134 and 136 preventing further movement of cover 125 as
soon as bottle-receiving chamber 37 is completely opened. After
aerosol container 43 has been pressed into position in
bottle-receiving chamber 37, cover 125 is pushed forward.
Initially, as the forward end of wedge 132 starts to slide up on
the bottom of container 43, wedge portion 129 is relatively free to
slide backward relative to sliding cover 125. As wedge 129
continues to slide forward over container 43 the resistance to
movement because of the interaction of notches 135 increases
sufficiently to lock wedge 129 relative to cover plate 125. Further
movement of cover plate 125 forces the container 43 into position
in bottle-receiving chamber 37. A ridge 139 of minor width is
provided on the bottom of sliding cover 125 in a position to engage
the inside of abutment 138 to hold cover 125 in its closed
position.
This arrangement works very well in the case of metal aerosol
containers where tolerances can be maintained carefully and the
overall distance between the outside of case 46 and the bottom of
aerosol container 43 varies but a few thousandths of an inch at the
most. In the case of glass containers where the variation may be as
much as one-eighth inch .+-. some degree of jamming sometimes
results. In such instances a second version of the sliding wedge is
preferred.
In this second version, shown in FIG. 13, notches 135 are entirely
removed permitting boss 133 to slide freely in groove 134. Wedge
portion 139 is urged forwardly by a spring 141 mounted between the
rear of wedge 132 and abutment 138. A rearwardly extending lug 142
may be provided on wedge 142 to support one end of spring 141.
* * * * *