CA1053213A - Method and apparatus for metering fluids - Google Patents
Method and apparatus for metering fluidsInfo
- Publication number
- CA1053213A CA1053213A CA258,207A CA258207A CA1053213A CA 1053213 A CA1053213 A CA 1053213A CA 258207 A CA258207 A CA 258207A CA 1053213 A CA1053213 A CA 1053213A
- Authority
- CA
- Canada
- Prior art keywords
- tubing
- portions
- opposed
- cam
- tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M39/00—Tubes, tube connectors, tube couplings, valves, access sites or the like, specially adapted for medical use
- A61M39/22—Valves or arrangement of valves
- A61M39/28—Clamping means for squeezing flexible tubes, e.g. roller clamps
- A61M39/285—Cam clamps, e.g. roller clamps with eccentric axis
Landscapes
- Health & Medical Sciences (AREA)
- Heart & Thoracic Surgery (AREA)
- Pulmonology (AREA)
- Engineering & Computer Science (AREA)
- Anesthesiology (AREA)
- Biomedical Technology (AREA)
- Hematology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Infusion, Injection, And Reservoir Apparatuses (AREA)
- Mechanically-Actuated Valves (AREA)
Abstract
Abstract of the Disclosure A clamp and related method provides for a stable fluid flow rate through a flexible tubing. The clamp comprises a body having an anvil and a tube-constricting cam that cooperates with the anvil to pinch together diametrically opposed sections of the tubing to provide a reduced flow passageway. The cross-sectional area of this passageway, and hence the fluid flow rate, is varied by rotating the cam to change the transverse extent of the pinched off portions. The reduced flow passageway is constrained at each adjustment of the clamp to prevent variations in flow rate due to displacement of the material of the tubing wall.
Description
1053Z~3 Back~round of the Invention This invention relates to adjustable clamps and methods for controlling the rate of fluid flow through flexible plastic tubing such as used for intravenous infusion of liquid nourishment and/or medication. The intravenous infusion of medicinal fluids is quite common in current medical practice. Anesthetics are infused intravenously during operations, and intravenous feeding is commonly employed in the post-operative period. In addition, there 10 are many patients whose illness either restricts their ;
ability to take food orally or to digest food properly so , taken, and these patients must be fed intravenously for the duration of their illness.
The apparatus commonly employed for intravenous ~j:
infusions includes a stand for supporting a bottle of the appropriate fluid in an elevated position above the patient. -~
A flexible plastic tube is coupled to the bottle for conduct-ing~the fluid from the bottle to the patient by a gravity feed.
A needle on the end of the flexible tube is inserted into ~t~ 20 one of the patient's veins, and an adjustable clamp on the tubing is used for controlling the flow rate of the fluid by~controlling~the cross sectional area of the tubing. In order~to measure the~flow rate with these devices it is necessary to caunt visually the number of drops per minute by~watching the drops in a drip chamber.
In the past, a problem has been encountexed in maintainLng a constant fluid flow rate through the flexible . . ,,~
ability to take food orally or to digest food properly so , taken, and these patients must be fed intravenously for the duration of their illness.
The apparatus commonly employed for intravenous ~j:
infusions includes a stand for supporting a bottle of the appropriate fluid in an elevated position above the patient. -~
A flexible plastic tube is coupled to the bottle for conduct-ing~the fluid from the bottle to the patient by a gravity feed.
A needle on the end of the flexible tube is inserted into ~t~ 20 one of the patient's veins, and an adjustable clamp on the tubing is used for controlling the flow rate of the fluid by~controlling~the cross sectional area of the tubing. In order~to measure the~flow rate with these devices it is necessary to caunt visually the number of drops per minute by~watching the drops in a drip chamber.
In the past, a problem has been encountexed in maintainLng a constant fluid flow rate through the flexible . . ,,~
2 -`: ~
:
:: : ` ; ;;: , -~l~S3213 plastic tubing (usually polyvinylchloride) because of its physical characteristics. After the desired fluid flow rate has been set with the adJustable clamp, as by restrict-ing a portion of the cross-section of the tubing, the plastic wall of the tubing nevertheless tends to deform or displace slowly resulting in a progressive change in the cross sectional area through which the fluid is flowing~ thereby progressively changing the fluid flow rate through the tubing.
This requires frequent readjustment of the clamp in order to make sure that the correct fluid flow rate is maintained.
Tests have shown that the standard intravenous set loses an av-erage of 45% of its initial flow rate in ten minutes if not readjusted.
Objects and Summary of the Invention A principle object of this invention is to provide for accurately controlling the flow rate through a length of flexible tubing. In general this is accomplished by a method and apparatus which involves clamping the tubing in such a manner that the cross sectional area within the tubing for fl~id flow is effectively prevented from changing, once hav-i~g been set, by the use of proper clamping and constraining forces on the tubing and by localizing the areas of these forces.
In the method of this invention the tubing is pinched shut laterally in tw~ opposed zones leaving a central region or passageway which is regulated from full "on" to full "off"
and vsrious drlp r~tes therebetween. Esch of the two opposed , .. . . . .
1t~53Z13 zones is subdivided into an end or outer region at which the tubing is pinched or compressed shut but avoiding rupture of ; the tube, and an inner region at which the tubing is com-- pressed to less than the combined thickness of the two walls that are pressed together and sufficient to prevent subsequent change of the cross section of said passageway The invention comprises a clamp for providing a stable fluid flow rate through a flexible tubing, said c~amp comprising means fonning a surface for receiving a portion of said tubing and supporting the same, and tube-constricting means having first portions coope~ating with first parts of said surface for providing opposed structures that compress diametrically opposed wall portions of the :~
tubing an amount sufficient to shut off the tubing at spaced regions, and said constricting means also having means coop-.
erating w~bh a second part of said surface for providing structure defining a space for a reduced-flow passageway in the tubing, said opposed structures and said first portions ~- being shaped to apply sufficient pressure to the tubing to reduce the wall thickness of the tubing, said structure defin-I, ing the space for said reduced flow passageway being between j said opposed structures, said opposed structures and the I structure defining said space together providing a !
~ substantisl confinement for the tubing extending around the : tubing, said constri¢ting means including arm structure piv-otal relative to said surface end including spaced peripheral .. _4_ s . ., .
~053Z13 parts constituting said first portions, said spaced peripheral parts upon pivoting of said arm structure presenting progressively greater areas against said tubing to vary the extent of each of said spaced regions transversely of the ~ :
tubing, and said first parts being transversely o~ the tubing.
The invention further comprises a method of control-ling the fluid flow rate ~hrough a reduced flow passageway in length of flexible plastic tubing in such a manner as to minimize flow rate variations in said passageway due to vari ations in cross-sectional area thereof resulting from displace-ment of the material of the tubing, said method comprising . :
the steps of constraining a section of the tubing in a path that extends completely around the circumference of said J
tubing, and laterally pinching two diametrically opposed. :
portions of the tubing together by a force exerted from the outside in and within said constrained path to shut said tub-ing at said pinched portions and provide said reduced flow passageway between said two shut portions and with the opposed portions being restricted to relatively narrow zones trans- :
versely of the tube, the con~trained path being such as to ., . prevent significant displacement of the tubing and the pinch-ing forces beJ~ng of sufficient magnitude that the tubing in at least a part of each of said opposed portions is reduced ~ in wall thickness and remains closed at said opposed portions ::~ over comparatively long periods of time, and varying the cross-i sectional area of said passageway in a selected manner to - ~
.` ';~ .
. ' . ..
~ 1~53Z~3 vary the fluid flow therethrough, said varying being effected by increasing or decreasing the extent of said opposed pinched portions transversely of the tubing; and in which each of said opposed portions comprises an inner region adjacent an end region, and pinching said inner region shut to an e~tent that is greater than that of said end region.
B~I-f Description of the Figures Fig. 1 is a perspective view of a clamp constructed in accordance with and embodying the present invention;
Fig. 2 is a vertical sectional view of the clamp of Fig. 1 taken substantially through the longitudinal center ` ~-line of the cam lever and the longitudinal center line of the tube but showing the cam arm and cam rotated from the position of Fig. 1 to the full open position;
Fig. 3 is an en~arged fragmentary secti~ha~ iew-~
taken along line 3-3 of Fig. 2;
Fig. 4 is an enlarged fra~mentary side elevational view of the cam lever and the cam that is at one end thereof;
Flg. 5 is an enlarged fragmentary sectional view taken along line 5-5 of Fig. 2 in the full open position;
;`, Fig. 6 is a fragmentary sectional view taken appro~imately along line 6-6 of Fig. 4 but showing the cam assembled with the body and rotated to a position such that ~, line 6-6 is normal to the anvil, and the tubing is partially -~ constricted;
', Fig. 7 is a view similar to Fig. 6 and showing a ~' further rot~ted position of the cam and as seen from line 7-~7 of Fig. 4 and wherein the tubing is constricted to permit trickle of fluid to flow therethrough.
'"~ :
: ., . - . .
1C~53213 Fig. 8 i~ a view similar to Fig. 6 and showing a further rotated position of the cam as seen from line 8-8 of Fig. 4 and in whi-~h the flow through the tubing will b~o at a low drip rate, Fig. 9 is a view similar to Fig. 6 and showing still another rotated position of the cam as seen from line 9-9 of Fig, 4 and in which the tubing is completely s~ut off;
Fig, 10 shows a modified form of the invention; and Fig. 11 shows a still further modlfied form of the 10 invention.
Detailed DescriPtion Referring now in more de~ail to the drawings there is shown a clamp 2 having a body 4 in which there is positioned an arm structure 6 comprising generally a cam 8 and an arm or lever 10. Generally speaking, the body 4 rotatably supports ` the cam 8, the latter being rotated by manipulation o a lever 10 to which it is integrally connected. The body 4 has a ~ tube-supporting surface or anvil 12 that receives the plastic r tubing 14, and the peripheral surface 16 of the cam 8 cooper-20 ates with the anvil 12 to constrict the tube ~hereby to vary ' .
,~ ~ the flow rate therethrough from substantially full flow to complete Qhut off, as will be presently more fully described.
; The width of the anvil surface 12 between side walls 5,5 (Fig. 5) is approxi~ately the same as the width of the tubing -when flattened. The dimension of the anvil surface 12 at right ~ ` f~
angles to said width should be narrow but not so narrow as to : i :
~, .,, . , .. . ., ; . ,,. : .. : .
. .. . .. .
.~. . , . .. . , ' ' .
~ ~5 3Z ~3 approach a knife edge that would cut the tube. Preferably said dimension is approximately the same as twice the wall thickness of the tube.
The body 4 further comprises a central bulb-like housing portion 18 having opposed cylindrical sockets 20,20 and a generally U-shaped channel 22 extending from the region of the socket 20,20 outwardly of the housing portion 18.
Opposite from the channel 22 the housing portion 18 has an opening 24 which terminates adjacent to the sockets 20,20 in retaining lips 26,26. The opening 24 also has a generally srcuate section 28 for receiving a portion of the tube, as best seen in Figs.'l and 2, when the clamp is mounted on :1 'i the tube.
. ::
~'~ Also formed in the housing portion 18 is a slot 30 : .
~ which extends approximately 180 to prov~ide'clearance for . , ~ -the lever 10, enabling the latter also to move approximately 180. ~The slot 30 is bounded on one side by a guard or shield 32 which extends approximately 90 arcuately as best seen in Fig.~ The~shield 32 also extends outwardly to a periphery ,' 20 34 which is~sIightly short of the radial extent or free end --'' of~the lever 10, The shield 32 preferably constitutes an - ~extension o~f~one wall of the channel 22 and at its radially ~ir~er~end~is~integral with the housing~portion 18. The shield~helps to prevent~accidental vement of the leyer 10 over~the~90~of~movement that is most critical and which will be~generQIIy usFd In intravenou~ ieeding, :
r,~ . . : . : . : , - ' . : ~ .
,.: , . . : ~ ~ , .
' . : ' : ' .
Centrally thereof the housing portion 18 is integrallv formed with a stiffening flange structure 36 from which there are two groups bifurcated radial projections 38,38. Each pair of projec~ions 38 provide a temporary tube shut-off structure to be used when changing intravenous solution bottles. Thus, an intravenous supply tube, like the tube 14, can be inserted into the slot between each pair of projections 38 to constrict the tube to shut it off tempo-rarily. For example, this may be done with a dual bottle apparatus using a "Y" fitting to supply a single tube that delivers fluid to the patient. Each bottle can be shut off sep-arately or at the same time.
Within the channel 22 and spaced from the sockets 20,20 the body 4 integrally includes a guide 40 which serves to retain the tubing 14 in the channel 22. The guide 40 also aids in assembling the tube 14 with the clamp 2 because the guide 40 guides the tube 14 into the space between the anvil 12 and the cam periphery 16, as best seen in Fig. 2. In assembling the tube 14 with the clamp, the tube is passed through the openings 24,28 with the lever 10 and cam 8 in the full open positions shown in Figs. 2 and 5. The tube will a~sume a slight bend near the anvil 12. The guide 40 helps prevent the clamp from sliding on the tube when the clamp is fully open as in Fig. 2.
Jl In the form of the invention herein shown, the body j~ 4 and the arm structure or cam-lever unit 6 constitute two J molded plastic pieces that make up the clamp. The plastic .
. .
.
1053Z~3 may be a high density polyethylene, but other plastics may be used. The two plastic pieces are sufficiently yieldable elastically so that they may be readily assembled. This reduces the manufacturing costs of the clamp.
Referring again to the cam 8 it will be seen that it has opposed trunions 42,42 which are of cylind~ical con-figurations and which are shaped to fit slidably and conform-ably (but with some friction) in the sockets 20,20. The trunions 42,42 thus rotate about an axis 21 which is generally ;i:
transverse to the longitudinal axis of the tubing 14. The l opening 24 is sized for receiving the trunions 42,42 during ~'3 assembly of the cam with the housing portion 18. As the trunions 42,42 are moved past the lips 26,26, the latter are caused to distend but they snap back into their normal positions when the trunions 42,42 have become seated in the sockets 20,20. The lips 26,26 thus retain the cam 8 assembled with tbe housing portion 18. '~
The peripheral tube-constricting surface 16 of the cam 8~is uniquely~designed to cooperate with the anvil 12 '' 20 to control the flow of fluid in the tubing 14. The axis 21 ~- ~ of the;cam~8 is the axis of rotation of the trunions 42;
S~ however, çertain portions~of the cam surface 16 are eccentric -' ~ to the~axis~21 as will~hereinafter be deseribed. The - ~ rotational~position~of the cam 8 determines the flow rate ;through~the tubing. ~;
- ~ Figs. 6 -:9~show~positions of the cam in the last 90~of~movement, i.e.where the lever 10 is in the region of lOS3~13 the shield 32, The cam 8 has first peripheral portions 44,44 cooperating with first parts 46,46 of the anvil surface to pinch shut diametrically opposed portions of the tubing 14 on opposite sides of the longitudinal axis of the tubing. In the outer regions 44a,44a the tubing wall is pinched shut and constricted to slightly less than the normal wall thickness.
Overconstricting the tube at the regions 44a should be avoided in order to prevent tube rupture~ In the regions44bh4b the tubing wall is preferably compressed to about one half its normal thickness. Central region 44c forms a second portion of the cam periphery that cooperates with a second part or groove 48 of the anvil to define a confinement structure for a reduced flow passageway 50 of the tubing. The tubing is thus pinched shut except at the passageway 50 where the tubing is confined to prevent displacement and consequent ^
change in cross-sectional area. Thus the flow rate is main-tained as adjusted.
At various angular positions about the cam axis central region 44c has its surface portions 45,47 at varying distances from the a~is of rotation 21 of the cam 8 while the end regions 44a,44b have their respective surface portions at ;
constant distances from the axis of rotation 21 of the cam.
The result is that the central region 44c forms a cavity which tends to flatten out or become shallower as the cam is rotated from a tube-open position shown in Fig. 6 through the'trickle" position of Fig. 7 and the "slow drip" position of Fig. 8 to a tube fully-closed position shown in Fig. 9 .. , . , ~ ' . , ~ ' ' . '~
'' : ' ' ' ' , ' , . ~ ' ' , ~ ' ' ~ ' ' ' .
while the tube at the region 44a remains confined to a relatively constant extent. During such cam movement the regions 44b,44b that are presented against the tubing become progressively wider. Viewed another way, the angle formed by the surfaces 45,47 become less and less obtuse as the cam is rotated from the tube-closed position shown in Figure 9 to the position of Figure 6 resulting in the cavity formed by the surfaces 45,47 "pulling away" from the tubing to allow the size of passageway 50 to increase. When the condition of Figure 9 is reached, the cam surface that is presented toward the tubing is substantially flat, that is surface portions 45,47 form approximately a straight angle.
The groove 48 is preferably of rectangular cross section. The groove 48 serves to confine the reduced flow passageway 50 to aid in preven,ting changes in the cross-section of the passageway due to displacement of the tubing wall once the flow rate has been set by the position of the cam 8. ' '~
The lever operated cam 8 provides a first class ~lever wLth~substantial mechanical advantage that facilitates application of the necessary constricting and confin,ing, forces to the tubing. The lever 10 operates in conjunction with~the ourfaces 45,47 that~converge in a direction generally toward~the 8XiS of rotat~ion 21 of the cam to provide a recess of~varying depth for'confining the reduced flow passageway 50, ~-Fig. lO shows a modified form of the invention in which the~groove or recess 48 is eliminated from the anvil 12 ,. . . . .. . . . . .
10~3Z~3 and instead is formed as a groove 51 in the cam 8a. This groove 51 will be located centrally of the cam 8a, that is in the region of juncture of the surfaces 45,47. Otherwise, the arrangement in Fig. 10 is the same as that in Figs. 1-9.
Figure 11 is a further modified form of the invention in which the difference lies in the fact that grooves 51 and 48 are in both the cam and in the anvil. The groove 51 need only be very shallow, for example, of the order of a few thousands of an inch. The anvil surface may : . . .
be as in Figs. 1 - 10 or the anvil surface may have a shoulder or step 53 at each side to relieve the side quadrants 55 of the tubing to prevent overstressing thereof.
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'~'' ,'""'' '"'' .,.". "'"' "~ ~' " '' ; ' .' '' ' " ''' ,' '
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:: : ` ; ;;: , -~l~S3213 plastic tubing (usually polyvinylchloride) because of its physical characteristics. After the desired fluid flow rate has been set with the adJustable clamp, as by restrict-ing a portion of the cross-section of the tubing, the plastic wall of the tubing nevertheless tends to deform or displace slowly resulting in a progressive change in the cross sectional area through which the fluid is flowing~ thereby progressively changing the fluid flow rate through the tubing.
This requires frequent readjustment of the clamp in order to make sure that the correct fluid flow rate is maintained.
Tests have shown that the standard intravenous set loses an av-erage of 45% of its initial flow rate in ten minutes if not readjusted.
Objects and Summary of the Invention A principle object of this invention is to provide for accurately controlling the flow rate through a length of flexible tubing. In general this is accomplished by a method and apparatus which involves clamping the tubing in such a manner that the cross sectional area within the tubing for fl~id flow is effectively prevented from changing, once hav-i~g been set, by the use of proper clamping and constraining forces on the tubing and by localizing the areas of these forces.
In the method of this invention the tubing is pinched shut laterally in tw~ opposed zones leaving a central region or passageway which is regulated from full "on" to full "off"
and vsrious drlp r~tes therebetween. Esch of the two opposed , .. . . . .
1t~53Z13 zones is subdivided into an end or outer region at which the tubing is pinched or compressed shut but avoiding rupture of ; the tube, and an inner region at which the tubing is com-- pressed to less than the combined thickness of the two walls that are pressed together and sufficient to prevent subsequent change of the cross section of said passageway The invention comprises a clamp for providing a stable fluid flow rate through a flexible tubing, said c~amp comprising means fonning a surface for receiving a portion of said tubing and supporting the same, and tube-constricting means having first portions coope~ating with first parts of said surface for providing opposed structures that compress diametrically opposed wall portions of the :~
tubing an amount sufficient to shut off the tubing at spaced regions, and said constricting means also having means coop-.
erating w~bh a second part of said surface for providing structure defining a space for a reduced-flow passageway in the tubing, said opposed structures and said first portions ~- being shaped to apply sufficient pressure to the tubing to reduce the wall thickness of the tubing, said structure defin-I, ing the space for said reduced flow passageway being between j said opposed structures, said opposed structures and the I structure defining said space together providing a !
~ substantisl confinement for the tubing extending around the : tubing, said constri¢ting means including arm structure piv-otal relative to said surface end including spaced peripheral .. _4_ s . ., .
~053Z13 parts constituting said first portions, said spaced peripheral parts upon pivoting of said arm structure presenting progressively greater areas against said tubing to vary the extent of each of said spaced regions transversely of the ~ :
tubing, and said first parts being transversely o~ the tubing.
The invention further comprises a method of control-ling the fluid flow rate ~hrough a reduced flow passageway in length of flexible plastic tubing in such a manner as to minimize flow rate variations in said passageway due to vari ations in cross-sectional area thereof resulting from displace-ment of the material of the tubing, said method comprising . :
the steps of constraining a section of the tubing in a path that extends completely around the circumference of said J
tubing, and laterally pinching two diametrically opposed. :
portions of the tubing together by a force exerted from the outside in and within said constrained path to shut said tub-ing at said pinched portions and provide said reduced flow passageway between said two shut portions and with the opposed portions being restricted to relatively narrow zones trans- :
versely of the tube, the con~trained path being such as to ., . prevent significant displacement of the tubing and the pinch-ing forces beJ~ng of sufficient magnitude that the tubing in at least a part of each of said opposed portions is reduced ~ in wall thickness and remains closed at said opposed portions ::~ over comparatively long periods of time, and varying the cross-i sectional area of said passageway in a selected manner to - ~
.` ';~ .
. ' . ..
~ 1~53Z~3 vary the fluid flow therethrough, said varying being effected by increasing or decreasing the extent of said opposed pinched portions transversely of the tubing; and in which each of said opposed portions comprises an inner region adjacent an end region, and pinching said inner region shut to an e~tent that is greater than that of said end region.
B~I-f Description of the Figures Fig. 1 is a perspective view of a clamp constructed in accordance with and embodying the present invention;
Fig. 2 is a vertical sectional view of the clamp of Fig. 1 taken substantially through the longitudinal center ` ~-line of the cam lever and the longitudinal center line of the tube but showing the cam arm and cam rotated from the position of Fig. 1 to the full open position;
Fig. 3 is an en~arged fragmentary secti~ha~ iew-~
taken along line 3-3 of Fig. 2;
Fig. 4 is an enlarged fra~mentary side elevational view of the cam lever and the cam that is at one end thereof;
Flg. 5 is an enlarged fragmentary sectional view taken along line 5-5 of Fig. 2 in the full open position;
;`, Fig. 6 is a fragmentary sectional view taken appro~imately along line 6-6 of Fig. 4 but showing the cam assembled with the body and rotated to a position such that ~, line 6-6 is normal to the anvil, and the tubing is partially -~ constricted;
', Fig. 7 is a view similar to Fig. 6 and showing a ~' further rot~ted position of the cam and as seen from line 7-~7 of Fig. 4 and wherein the tubing is constricted to permit trickle of fluid to flow therethrough.
'"~ :
: ., . - . .
1C~53213 Fig. 8 i~ a view similar to Fig. 6 and showing a further rotated position of the cam as seen from line 8-8 of Fig. 4 and in whi-~h the flow through the tubing will b~o at a low drip rate, Fig. 9 is a view similar to Fig. 6 and showing still another rotated position of the cam as seen from line 9-9 of Fig, 4 and in which the tubing is completely s~ut off;
Fig, 10 shows a modified form of the invention; and Fig. 11 shows a still further modlfied form of the 10 invention.
Detailed DescriPtion Referring now in more de~ail to the drawings there is shown a clamp 2 having a body 4 in which there is positioned an arm structure 6 comprising generally a cam 8 and an arm or lever 10. Generally speaking, the body 4 rotatably supports ` the cam 8, the latter being rotated by manipulation o a lever 10 to which it is integrally connected. The body 4 has a ~ tube-supporting surface or anvil 12 that receives the plastic r tubing 14, and the peripheral surface 16 of the cam 8 cooper-20 ates with the anvil 12 to constrict the tube ~hereby to vary ' .
,~ ~ the flow rate therethrough from substantially full flow to complete Qhut off, as will be presently more fully described.
; The width of the anvil surface 12 between side walls 5,5 (Fig. 5) is approxi~ately the same as the width of the tubing -when flattened. The dimension of the anvil surface 12 at right ~ ` f~
angles to said width should be narrow but not so narrow as to : i :
~, .,, . , .. . ., ; . ,,. : .. : .
. .. . .. .
.~. . , . .. . , ' ' .
~ ~5 3Z ~3 approach a knife edge that would cut the tube. Preferably said dimension is approximately the same as twice the wall thickness of the tube.
The body 4 further comprises a central bulb-like housing portion 18 having opposed cylindrical sockets 20,20 and a generally U-shaped channel 22 extending from the region of the socket 20,20 outwardly of the housing portion 18.
Opposite from the channel 22 the housing portion 18 has an opening 24 which terminates adjacent to the sockets 20,20 in retaining lips 26,26. The opening 24 also has a generally srcuate section 28 for receiving a portion of the tube, as best seen in Figs.'l and 2, when the clamp is mounted on :1 'i the tube.
. ::
~'~ Also formed in the housing portion 18 is a slot 30 : .
~ which extends approximately 180 to prov~ide'clearance for . , ~ -the lever 10, enabling the latter also to move approximately 180. ~The slot 30 is bounded on one side by a guard or shield 32 which extends approximately 90 arcuately as best seen in Fig.~ The~shield 32 also extends outwardly to a periphery ,' 20 34 which is~sIightly short of the radial extent or free end --'' of~the lever 10, The shield 32 preferably constitutes an - ~extension o~f~one wall of the channel 22 and at its radially ~ir~er~end~is~integral with the housing~portion 18. The shield~helps to prevent~accidental vement of the leyer 10 over~the~90~of~movement that is most critical and which will be~generQIIy usFd In intravenou~ ieeding, :
r,~ . . : . : . : , - ' . : ~ .
,.: , . . : ~ ~ , .
' . : ' : ' .
Centrally thereof the housing portion 18 is integrallv formed with a stiffening flange structure 36 from which there are two groups bifurcated radial projections 38,38. Each pair of projec~ions 38 provide a temporary tube shut-off structure to be used when changing intravenous solution bottles. Thus, an intravenous supply tube, like the tube 14, can be inserted into the slot between each pair of projections 38 to constrict the tube to shut it off tempo-rarily. For example, this may be done with a dual bottle apparatus using a "Y" fitting to supply a single tube that delivers fluid to the patient. Each bottle can be shut off sep-arately or at the same time.
Within the channel 22 and spaced from the sockets 20,20 the body 4 integrally includes a guide 40 which serves to retain the tubing 14 in the channel 22. The guide 40 also aids in assembling the tube 14 with the clamp 2 because the guide 40 guides the tube 14 into the space between the anvil 12 and the cam periphery 16, as best seen in Fig. 2. In assembling the tube 14 with the clamp, the tube is passed through the openings 24,28 with the lever 10 and cam 8 in the full open positions shown in Figs. 2 and 5. The tube will a~sume a slight bend near the anvil 12. The guide 40 helps prevent the clamp from sliding on the tube when the clamp is fully open as in Fig. 2.
Jl In the form of the invention herein shown, the body j~ 4 and the arm structure or cam-lever unit 6 constitute two J molded plastic pieces that make up the clamp. The plastic .
. .
.
1053Z~3 may be a high density polyethylene, but other plastics may be used. The two plastic pieces are sufficiently yieldable elastically so that they may be readily assembled. This reduces the manufacturing costs of the clamp.
Referring again to the cam 8 it will be seen that it has opposed trunions 42,42 which are of cylind~ical con-figurations and which are shaped to fit slidably and conform-ably (but with some friction) in the sockets 20,20. The trunions 42,42 thus rotate about an axis 21 which is generally ;i:
transverse to the longitudinal axis of the tubing 14. The l opening 24 is sized for receiving the trunions 42,42 during ~'3 assembly of the cam with the housing portion 18. As the trunions 42,42 are moved past the lips 26,26, the latter are caused to distend but they snap back into their normal positions when the trunions 42,42 have become seated in the sockets 20,20. The lips 26,26 thus retain the cam 8 assembled with tbe housing portion 18. '~
The peripheral tube-constricting surface 16 of the cam 8~is uniquely~designed to cooperate with the anvil 12 '' 20 to control the flow of fluid in the tubing 14. The axis 21 ~- ~ of the;cam~8 is the axis of rotation of the trunions 42;
S~ however, çertain portions~of the cam surface 16 are eccentric -' ~ to the~axis~21 as will~hereinafter be deseribed. The - ~ rotational~position~of the cam 8 determines the flow rate ;through~the tubing. ~;
- ~ Figs. 6 -:9~show~positions of the cam in the last 90~of~movement, i.e.where the lever 10 is in the region of lOS3~13 the shield 32, The cam 8 has first peripheral portions 44,44 cooperating with first parts 46,46 of the anvil surface to pinch shut diametrically opposed portions of the tubing 14 on opposite sides of the longitudinal axis of the tubing. In the outer regions 44a,44a the tubing wall is pinched shut and constricted to slightly less than the normal wall thickness.
Overconstricting the tube at the regions 44a should be avoided in order to prevent tube rupture~ In the regions44bh4b the tubing wall is preferably compressed to about one half its normal thickness. Central region 44c forms a second portion of the cam periphery that cooperates with a second part or groove 48 of the anvil to define a confinement structure for a reduced flow passageway 50 of the tubing. The tubing is thus pinched shut except at the passageway 50 where the tubing is confined to prevent displacement and consequent ^
change in cross-sectional area. Thus the flow rate is main-tained as adjusted.
At various angular positions about the cam axis central region 44c has its surface portions 45,47 at varying distances from the a~is of rotation 21 of the cam 8 while the end regions 44a,44b have their respective surface portions at ;
constant distances from the axis of rotation 21 of the cam.
The result is that the central region 44c forms a cavity which tends to flatten out or become shallower as the cam is rotated from a tube-open position shown in Fig. 6 through the'trickle" position of Fig. 7 and the "slow drip" position of Fig. 8 to a tube fully-closed position shown in Fig. 9 .. , . , ~ ' . , ~ ' ' . '~
'' : ' ' ' ' , ' , . ~ ' ' , ~ ' ' ~ ' ' ' .
while the tube at the region 44a remains confined to a relatively constant extent. During such cam movement the regions 44b,44b that are presented against the tubing become progressively wider. Viewed another way, the angle formed by the surfaces 45,47 become less and less obtuse as the cam is rotated from the tube-closed position shown in Figure 9 to the position of Figure 6 resulting in the cavity formed by the surfaces 45,47 "pulling away" from the tubing to allow the size of passageway 50 to increase. When the condition of Figure 9 is reached, the cam surface that is presented toward the tubing is substantially flat, that is surface portions 45,47 form approximately a straight angle.
The groove 48 is preferably of rectangular cross section. The groove 48 serves to confine the reduced flow passageway 50 to aid in preven,ting changes in the cross-section of the passageway due to displacement of the tubing wall once the flow rate has been set by the position of the cam 8. ' '~
The lever operated cam 8 provides a first class ~lever wLth~substantial mechanical advantage that facilitates application of the necessary constricting and confin,ing, forces to the tubing. The lever 10 operates in conjunction with~the ourfaces 45,47 that~converge in a direction generally toward~the 8XiS of rotat~ion 21 of the cam to provide a recess of~varying depth for'confining the reduced flow passageway 50, ~-Fig. lO shows a modified form of the invention in which the~groove or recess 48 is eliminated from the anvil 12 ,. . . . .. . . . . .
10~3Z~3 and instead is formed as a groove 51 in the cam 8a. This groove 51 will be located centrally of the cam 8a, that is in the region of juncture of the surfaces 45,47. Otherwise, the arrangement in Fig. 10 is the same as that in Figs. 1-9.
Figure 11 is a further modified form of the invention in which the difference lies in the fact that grooves 51 and 48 are in both the cam and in the anvil. The groove 51 need only be very shallow, for example, of the order of a few thousands of an inch. The anvil surface may : . . .
be as in Figs. 1 - 10 or the anvil surface may have a shoulder or step 53 at each side to relieve the side quadrants 55 of the tubing to prevent overstressing thereof.
~J ~
'i~ ~ ',' ~, , .~ ~" ~
'~'' ,'""'' '"'' .,.". "'"' "~ ~' " '' ; ' .' '' ' " ''' ,' '
Claims (8)
1. A clamp for providing a stable fluid flow rate through a flexible tubing, said clamp comprising means form-ing a surface for receiving a portion of said tubing and supporting the same, and tube-constricting means having first portions cooperating with first parts of said surface for providing opposed structures that compress diametrically opposed wall portions of the tubing an amount sufficient to shut off the tubing at spaced regions, and said constricting means also having means cooperating with a second part of said surface for providing structure defining a space for a reduced-flow passageway in the tubing, said opposed structures and said first portions being shaped to apply sufficient pressure to the tubing to reduce the wall thickness of the tubing, said structure defining the space for said reduced flow passageway being between said opposed structures, said opposed structures and the structure defining said space together providing a substantial confinement for the tubing extending around the tubing, said constricting means including arm structure pivotal relative to said surface and including spaced peripheral parts constituting said first portions, said spaced peripheral parts upon pivoting of said arm structure presenting progressively greater areas against said tubing to vary the extent of each of said spaced regions transversely of the tubing, and said first parts being relatively narrow to restrict said regions to narrow bands transversely of the tubing.
2. A clamp according to claim 1 in which the distance from the axis of said pivotal structure to at least one of said peripheral portions is such that rotation of said arm structure about said axis varies the cross-sectional area of said reduced flow passageway.
3. A clamp according to claim 2 in which arm structure comprises a first class lever.
4. A clamp for providing a stable fluid flow rate through a flexible tubing, said clamp comprising a body having means including an anvil for receiving and supporting a portion of said tubing, a cam rotatable in said body about a substantially fixed axis generally transverse to the longi-tudinal axis of said tubing portion, said cam having opposed peripheral portions on opposite sides of the longitudinal axis of said tubing portion, said peripheral portions having tube-constricting surfaces cooperating with said anvil to shut off diametrically opposed portions of said tubing portion, said anvil being relatively narrow in the direction transverse to said tubing, said cam and said anvil having cooperating portions between said tube-constricting surfaces that define a space for receiving and confining a reduced flow passageway of said tubing portion, said tube-constricting surfaces having sections thereof shaped to present tube-constricting surfaces of varying dimensions transversely of the tubing to vary the extent of the shut off portions transversely of the tubing and thereby vary the cross-section of said reduced flow passageway in accordance with various positions of said cam.
5. A clamp according to claim 4 which includes a groove in said cam which in part receives said reduced flow passageway.
6. A clamp according to claim 5 in which said space for said reduced flow passageway is in part defined by a groove in said anvil.
7. A method of controlling the fluid flow rate through a reduced flow passageway in length of flexible plastic tubing in such a manner as to minimize flow rate variations in said passageway due to variations in cross-sectional area thereof resulting from displacement of the material of the tubing, said method comprising the steps of constraining a section of the tubing in a path that extends completely around the circumference of said tubing, and laterally pinching two diametrically opposed portions of the tubing together by a force exerted from the outside in and within said constrained path to shut said tubing at said pinched portions and provide said reduced flow passageway between said two shut portions and with the opposed portions being restricted to relatively narrow zones transversely of the tube, the constrained path being such as to prevent significant displacement of the tubing and the pinching forces being of sufficient magnitude that the tubing in at least a part of each of said opposed portions is reduced in wall thickness and remains closed at said opposed portions over comparatively long periods of time, and varying the cross-sectional area of said passageway in a selected manner to vary the fluid flow therethrough, said varying being effected by increasing or decreasing the extent of said opposed pinched portions transversely of the tubing;
and in which each of said opposed portions comprises an inner region adjacent an end region, and pinching said inner region shut to an extent that is greater than that of said end region.
and in which each of said opposed portions comprises an inner region adjacent an end region, and pinching said inner region shut to an extent that is greater than that of said end region.
8. A method according to claim 7 in which said reduced wall thickness is less than about one-half of the nor-mal tube wall thickness.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/601,089 US4034773A (en) | 1973-12-10 | 1975-08-01 | Method and apparatus for metering fluids |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1053213A true CA1053213A (en) | 1979-04-24 |
Family
ID=24406184
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA258,207A Expired CA1053213A (en) | 1975-08-01 | 1976-07-30 | Method and apparatus for metering fluids |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1053213A (en) |
| DE (1) | DE2634553A1 (en) |
| FR (1) | FR2319882A1 (en) |
| GB (1) | GB1534165A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4013263A (en) * | 1975-12-24 | 1977-03-22 | Marvin Adelberg | Clamp for regulating fluid flow through plastic tubing |
| DK153288C (en) * | 1985-10-30 | 1988-11-14 | Coloplast As | HOSE CLAMP FOR A EXHAUST HOSE PIECE FROM A FLUID COLLECTION BAG |
| GB2214271A (en) * | 1987-12-30 | 1989-08-31 | Intellprop Corp | Fluid flow control means |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1348383A (en) * | 1970-05-01 | 1974-03-13 | Ometer Inc I V | Fluid flow control system |
| US3893468A (en) * | 1970-06-22 | 1975-07-08 | American Hospital Supply Corp | Clamp for flexible tube and method of regulating flow in such tube |
| US3813077A (en) * | 1972-06-29 | 1974-05-28 | E Kolic | Hose clamp |
-
1976
- 1976-07-30 CA CA258,207A patent/CA1053213A/en not_active Expired
- 1976-07-30 GB GB3190276A patent/GB1534165A/en not_active Expired
- 1976-07-31 DE DE19762634553 patent/DE2634553A1/en not_active Withdrawn
- 1976-08-02 FR FR7623619A patent/FR2319882A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2319882B1 (en) | 1982-11-12 |
| GB1534165A (en) | 1978-11-29 |
| DE2634553A1 (en) | 1977-02-17 |
| FR2319882A1 (en) | 1977-02-25 |
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