Suction control

A medical suction control unit of the type operated by occlusion of a control port to prevent entry of atmospheric pressure into a control chamber, in which the valving element is free to move bodily between open and closed positions in response to the closing and opening of the control port, with the vacuum bleed passage, which enables air to be withdrawn from the control chamber, establishing flow around the side of the valving element. The vacuum bleed passage is shown formed by a channel in one or the other of the contacting surfaces, at the point where the valve element rests upon a surface of the housing. The valve element is shown in the form of an elastomeric disk which has sufficient structural strength to resist detrimental deformation under vacuum, and which has sufficient thickness to guide itself in its bodily movement. In one form the unit employs a plug-form member attached to the valve element and entering the intake chamber to reduce objectionable noise. The unit can be assembled by mere insertation of the free-floating valve element and snap-fit of a cap into sealing relationship with the housing, or by indenting the walls of the housing to confine the free moving valve element within the housing.

BACKGROUND OF THE INVENTION 
In my U.S. Pat. No. 3,469,582 I have provided a surgical suction control 
unit employing a diaphragm which opens the flow passage by the simple 
procedure of covering a control hole, e.g. by use of the index finger of 
the person holding the unit. In this construction a vacuum bleed through a 
small passage maintains a vacuum level over the diaphragm, and holds the 
diaphragm in open position, when the finger closes the hole. However when 
the finger is removed from the control hole to allow ambient pressure to 
enter the control chamber, the higher pressure condition forces the 
diaphragm to close the flow passage. 
This control unit has been effective in surgical suction devices and other 
applications, but, in the constructions as taught in my prior patent and 
as made in production, significant problems have remained. 
One of the difficulties concerns the provision of an accurately sized 
vacuum bleed passage for connection of the control chamber to the vacuum 
source. If this passage is too large it wastes vacuum and the flow is 
noisy. If on the other hand this passage is too small, insufficient vacuum 
level is acquired in the control chamber and the unit does not function 
properly. In production, expensive molding dies having accurately fitted 
molding pins have been required to form such passages. 
Another difficulty concerns the fact that fluids being sucked through the 
device often contain substances which tend to clog the vacuum bleed 
passage. Because of the wish to have the passage self-cleaning, the 
preferred form of the invention has been a tiny hole molded into the thin 
diaphragm, as shown in FIGS. 12-15 of my prior patent. It has however been 
particularly difficult to size accurately this passage through the 
diaphragm. 
In the preferred embodiments of the past, the diaphragm, held by its 
periphery in the position as shown in FIGS. 12-15 of my prior patent, has 
been thin and flexible in order to achieve the proper flexing motion. Such 
a diaphragm has the disadvantage of making loud noise under certain flow 
conditions, for instance during partial clogging of the vacuum bleed 
passage or partial occlusion of the finger control port. The noise has 
been very high pitch, making the unit objectionable. 
Still other problems have concerned the time and expense of manufacture of 
the unit. In present commercial forms the parts must be clamped in a jig 
and the elements are then cemented together. 
Purposes of the present invention are to overcome these disadvantages and 
to provide an improved suction control unit. 
SUMMARY OF THE INVENTION 
The invention, in its various features, relates to a suction control unit 
comprising a housing, with a suction connection to a source of vacuum and 
an intake connection through which fluid is to be evacuated by the unit, 
the unit having a movable valving element exposed to a control chamber, 
means establishing a vacuum bleed passage between the suction side of the 
instrument and said control chamber and an occludable control port 
permitting entry of atmospheric pressure to said control chamber when the 
port is opened and preventing entry of atmospheric pressure when the 
control port is occluded. 
According to the invention the valving element comprises a relatively thick 
valving element disposed within the control chamber and free to move 
bodily between open and closed positions in response to varying pressure 
determined by the closing and opening of the control port, the vacuum 
bleed passage enabling air to be withdrawn from the control chamber around 
the side of the valving element. 
In preferred embodiments a surface portion of the valve element rests in 
contact upon a corresponding surface of the interior of the housing, and 
the vacuum bleed passage is defined by a channel formed in at least one of 
the contacting surfaces, this channel being in the form of a notch of 
molded form in the periphery of the valve element or in a valve 
element-supporting peripheral ledge of the housing. 
For noise suppression in which a central chamber is in communication with 
the intake connection of the unit and an annular chamber surrounds the 
central chamber, separated therefrom by an annular wall, with the annular 
chamber connected to the vacuum connection of the unit, a plug-form member 
is employed depending from the valve element and aligned to enter the 
central chamber when the valve element is in its closed position, the unit 
constructed to enable the plug-form member to be withdrawn from the 
central chamber by movement of the valve element upon the occlusion of the 
control port. 
For simplified construction of the unit a cover member defining the control 
port is snap fitted about walls of the housing in sealing relationship 
therewith or the housing defines a control port of a size substantially 
corresponding to the size of the valve element, the size being 
sufficiently small to enable occlusion of the port by the finger of the 
operator and inwardly protruding formations of the housing walls comprise 
a retainer means for the valve element. 
In preferred embodiments the valve element is of circular disk form, 
comprised of rubber and has a thickness of the order of 1.5 millimeters.

PREFERRED EMBODIMENTS 
Referring to FIG. 1 the control unit comprises a body member 10, a cap 
member 12 and a free-floating valve element 14, with the control chamber 
15 defined between the cap member and valve element. The body member 10 
has a suction connector 16 for connection to a vacuum source and an intake 
connector 18 for connection to the system to be evacuated by the unit. The 
body member also defines an inner annular separator wall 20 spaced 
inwardly from outer wall 22. The suction connector 16 is connected to the 
annular space 23 between walls 20 and 22 while the intake connector 18 
projects across space 23 and connects to the inner space 24 defined within 
the inner annular wall 20. At a height corresponding with the top edge 26 
of the inner annular wall 20, an inner ledge 28 is defined by the outer 
wall 22. An extension 25 of the outer wall extends upwardly from ledge 28 
to upper edge 30 and a securing rim 32 protrudes outwardly from the edge 
30. The dome or cap member 12, formed of resilient material, e.g, pvc, has 
a dependent rim 34 which resiliently snaps around the rim 32 and forces 
the cap member into sealing relationship with edge 30 of the outer wall. 
An atmospheric port 40 is formed through the substance of cap member 12 
while the outer surface of the cap member is shaped to be engaged by the 
finger of the operator as suggested in dotted lines. 
The free-floating valve element 14 is disposed within the space above ledge 
28. It comprises a circular member of silicone rubber of medium durometor 
and thickness of about 11/2 millimeters. Its diameter is less than the 
diameter of the upper extension 25 of outer wall, enabling free, 
non-sealed and non-restrained movement relative to outer wall 25. The 
valve element 14 is sized to have its outer margin rest upon ledge 28, 
while inward portion of the element bears upon edge 26 of the inner wall. 
The valve element has structural stability to remain in position when 
exposed to full vacuum at outer annular space 23 and while exposed along 
its top surface to atmospheric pressure. The structural stability of the 
element is also such that element 14 can guide itself along the annular 
wall in axial motion in response to changing pressure conditions. 
A notch 44 (see FIGS. 1a and 2) molded into the ledge 28 of the outer wall 
serves as a vacuum bleed passage between the annular vacuum space 23 and 
the control chamber 15, with air being drawn from the control chamber past 
the free peripheral edge of the valve element 14 through the notch-form 
passage 44 and into the vacuum connector 16. 
The valve element 14 is free to move axially back and forth within the 
confines of the extension 25 of the outer wall in response to pressure 
conditions. During operation, with the operator's finger off of the outer 
control port 40, atmospheric pressure, entering through the control port 
40, fills the control chamber 15 and bears downwardly upon the upper 
surface of the disc-form valve element 14. Simultaneously suction applied 
to connector 16 applies reduced pressure to the annular area of the valve 
element corresponding to the annular chamber 20. This draws the valve 
element tightly against the upper edge 26 of inner wall 20, forming a seal 
and preventing flow between connectors 18 and 16. 
When, however, the operator's finger is placed over the control port 40 as 
suggested by the dotted lines, atmospheric pressure is prevented from 
entering the control chamber 15. Rapidly the vacuum, acting through the 
bleed passage 44 at the ledge, draws air from the control chamber 15 to 
produce a vacuum condition in control chamber 15. Under this condition the 
atmospheric pressure entering through connector 18 into inner chamber 24 
is successful to push valve element 14 upwardly, to establish flow from 
connector 18 through chamber 24, over edge 26 of inner annular wall 20, 
thence to annular space 23 and to suction connector 16. 
A number of advantages are obtained by this construction. The vacuum bleed 
passage 44, being molded as a notch in a surface is inexpensive to 
fabricate in the mold, eliminating the need for molding pins and the 
expensive mold construction that must be employed with such pins. 
The free floating valve element 14, due to its relatively great thickness 
and mass causes any vibration that may occur to be of low frequency and 
amplitude, greatly reducing the noise of the unit. 
During construction, the valve element 14 is merely loosely dropped into 
the body and the cap 12 is snapped into place on the top of the unit to 
complete the manufacture. 
The variation of FIG. 3 is constructed to reduce noise even further. 
Central formation 50 formed integrally with valve element 14' fits 
slidingly with the wall 20 that defines the central chamber 24. Also the 
outer wall 25' is of extended height to enable the movement of valve 
element 14' over a wider range than in FIG. 1 to enable the plug 50 to be 
withdrawn from central chamber 24. In operation, when operator's finger is 
not occluding the control port 40 the atmospheric pressure causes valve 
element 14' to seal against edge 26 of inner annular wall 20, disposing 
inner plug member 50 within central chamber 24. 
During operation, when the operator's finger is placed over the control 
port 40 to change the pressure conditions, no significant flow occurs 
through the instrument until valve element 14' moves sufficiently to 
withdraw the central plug member 50 from the central cavity. At this time, 
when heavy flow is allowed to begin, the surrounding body of the valve 
element 14' has been withdrawn a substantial distance from the annular 
sealing surface 28, hence, because of the wide space between parts, there 
is virtually no opportunity for noise-producing vibrations to be 
established. 
Referring to FIGS. 4-6, in this embodiment the valve element 14" has a 
notch 44' formed in its periphery for establishing the restricted vacuum 
bleed passage between the control chamber and the vacuum chamber of the 
instrument. In this case the ledge 28' upon which the valve element seats 
has no notch. 
Also in this embodiment, the diameter D of the outer wall, FIG. 6, is of 
the order of a centimeter, permitting the finger of the operator to 
entirely occlude the control chamber, hence there is no need for a cap. In 
this case the top edge of the outer wall defines the control port. 
In construction of this unit, the valve element 14" is introduced into the 
body and then the upper wall is crimped to form inwardly protruding ears 
60 which confine the valve element within the unit. In FIG. 6 a suction 
tube 80 is connected to the unit. This suction tube leads to a system to 
be evacuated that is so constructed that only air passes through tube 80 
and hence the operator's finger is not exposed to contaminating liquids. 
In other instances the operator's finger is protected by a glove in the 
usual way.