Patent Description:
The present invention generally relates to fluid displacement and pressurizing devices for balloon catheters or the like, and more particularly relates to an improved screw plunger actuation and drive mechanism to control the displacement and pressurization of the working fluid.

Fluid displacement and pressurization devices adapted for selectively applying and relieving a measured pressure on a closed volume of fluid have been developed previously, such as for use in inflation of a balloon catheter used in angioplasty balloon procedures interiorly of blood vessels, or other types of balloon catheterization procedures.

Some examples of prior art devices for inflating and deflating a catheterized balloon device are disclosed in <CIT>; <CIT>; <CIT>; <CIT> and <CIT>.

The inflation device disclosed in <CIT> employs a threaded plunger and a release element constructed for selective threaded and unthreaded engagement with the threaded plunger. The plunger includes a handle for moving a piston within the device. However, the release element is not part of the handle, and therefore the device is not configured for single handed use.

The inflation device disclosed in <CIT> is unique in that it employs a plunger devoid of threads. Instead of the plunger including threads, the device employs a narrow, articulated thread bearing insert strip that is designed to deploy and engage surrounding mating threads. The narrow thread bearing insert strip relies, in part, upon force from a spring to maintain engagement under load. As such, a spring is called upon to bear the plunger's loading during pressurization. This is not ideal because the spring must be massive to withstand the plunger's load against it. For the plunger to handle a load from large pistons or high pressures devices, it must withstand plunger loadings of <NUM>-<NUM> lbF (<NUM>-<NUM> Newton).

The prior art device disclosed in the '<NUM> patent is designed such that loading upon the plunger is actually borne by a narrow threaded insert which pushes against a spring and traverses diagonally toward the plunger's center. Plunger loading pushes the insert into a direction of disengagement rather than engagement (i.e., proximally and toward the center of the plunger). Therefore, a load placed upon the plunger must be resisted by a strong return spring. Furthermore, the thread must be designed to retract in a path that is neutral to its thread face angles such that it will not hang up or push the plunger distally (pressurizing direction) when being released from load as it traverses diagonally inward. Still further, this traversing angle must be one that provides the return spring a degree of mechanical advantage by wedging the thread insert outward. The thread must therefore be designed exactly reverse of ideal by having a greater sloped face, one that is parallel to its diagonal angle of retraction, to bear the pressurization load instead of the opposite thread face which is more perpendicular to the plunger's axis. For ideal load handling, such a thread design is completely contrary to best practice. As a result of the device employing a threaded insert rather than providing threads directly on the plunger, the device is not capable of withstanding substantial plunger loading. Given the geometric limitations of the thread insert (as discussed above), the only way for the strip to handle more pressure would be with a spring so large as to be impractical or impossible to manually operate.

<CIT>; <CIT> and <CIT> disclose devices that provide improved syringing and pressurization control. All three patents are owned by the assignee of the present invention. These patents disclose quick actuating mechanisms which enable rapid advancement of a plunger and alternatively allow user controllable threaded engagement of a screw thread bearing plunger to achieve precise control during final pressurization of a balloon catheter. Both the '<NUM> and '<NUM> patents disclose similar devices that provide that a nut member is moved into and out of threaded engagement with a threaded plunger. The plunger has a handle, and the handle of the plunger and the actuating mechanism for engaging the nut member with the threaded plunger are separate mechanisms. As a result, neither one of the devices is configured for single hand use. Additionally, the devices have only a small surface area of thread engagement between the nut member and the threaded plunger, which results in more loading per thread compared to when there is a much larger surface area of engagement.

The '<NUM> patent discloses a device that is configured for one handed operation. However, the device is similar to the devices disclosed in the '<NUM> and '<NUM> patents in that the device only provides for a small surface area of thread engagement.

An object of an embodiment of the present invention is to provide a novel actuating mechanism for rapidly and selectively releasing or engaging a moveable threaded plunger, operable within a threaded member within a unitary syringe body.

Another object of an embodiment of the present invention is to provide a mechanism that is configured to control a high-pressure medical syringe for purposes of pressurizing, depressurizing and evacuating therapeutic medical balloon catheters, or the like.

Yet another object of an embodiment of the present invention is to provide a mechanism that provides for rapid manual reciprocation of a plunger, locking it in one place for precise thread controlled plunger advancement by means of plunger rotation as desired by the operator in order to either hold, displace, pressurize, depressurize or evacuate working fluid contained within a syringe.

Another object of an embodiment of the present invention is to provide a device that incorporates a threaded plunger design which provides a large surface area of thread engagement.

Still another object of an embodiment of the present invention is to provide a device that is configured such that operational loads between threaded members are transmitted directly by a plunger bearing a thread, and not indirectly through some intermediary component.

Briefly, an embodiment of the present invention provides a fluid displacement and pressurization device which provides both a substantial amount of thread engagement as well as provides for single hand control for all operational manipulations including maintaining a set fill volume, rapid filling and displacement, and pressurization and retention of evacuation positioning during balloon depressurization. The device allows for the use of one hand to not only transition the device from micro-movement control to macro-movement control, but also with regard to rotating, pushing or pulling the handle of the plunger.

The embodiment comprises a syringe body, a threaded plunger which extends into the syringe body, a threaded member inside the syringe body, control blades, a handle at an end of the plunger, and a control button in the handle. When the control button is not depressed, the control blades engage the threaded member with the threaded plunger. At that time, the handle of the plunger is rotatable to effect micro-movement of the plunger. The button in the handle is pressable to have the control blades disengage the threaded member from the threaded plunger inside the syringe body to allow for macro-movement of the plunger via pushing or pulling of the plunger into or out of the syringe body.

The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings wherein like reference numerals identify like elements in which:.

While this invention may be susceptible to embodiment in different forms, there are shown in the drawings and will be described herein in detail, specific embodiments with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to that as illustrated.

<FIG> illustrates a fluid displacement and pressurization device <NUM> which is in accordance with a first embodiment of the present invention. As shown, preferably the handle <NUM> of a plunger <NUM> is at one end of the fluid displacement and pressurization device <NUM> while the opposite end of the fluid displacement and pressurization device <NUM> is configured to engage a high pressure fluid delivery hose <NUM> (i.e., such as via a conventional hose-engaging socket). As shown, there may be a luer connector <NUM> at the end of the high pressure fluid delivery hose <NUM> that is connectable to, for example, a mating balloon catheter (not shown), or some other therapeutic medical device.

Preferably, the fluid displacement and pressurization device <NUM> includes a unitary syringe body <NUM> and the plunger <NUM> extends into the unitary syringe body <NUM>. As will be described in more detail later herein, the fluid displacement and pressurization device <NUM> is configured such that the plunger <NUM> is translatable relative to the unitary syringe body <NUM>, either by pushing or pulling on the handle <NUM> of the plunger, or by rotating the handle of the plunger. Translation of the plunger results in pressurization or depressurization of the mating balloon catheter (or other therapeutic medical device) that is connected to the luer connector <NUM> at the end of the high pressure fluid delivery hose <NUM>.

Preferably, the unitary syringe body has a barrel <NUM> and is entirely transparent (at least at the barrel <NUM>) to monitor the volume of working fluid within the barrel <NUM> and facilitate both fluid filling and purging of trapped and entrained air in preparation for use. As shown in <FIG>, the barrel <NUM> may have volume indicia thereon.

Typically, medical fluid pressurization devices such as those disclosed in the prior art patents referenced above are equipped with pressure monitoring features. Most commonly, they are equipped with traditional mechanical pressure gauges. These types of self-contained pressure gauges generally have their own threaded spigot, protective case and lens and they are most often secured to the device by means of threaded sockets or snap ring retaining features. Additionally, they must often be held in place with a bonding agent regardless of their primary retaining means in order to prevent rotation during use.

In contrast, preferably the medical fluid pressurization device <NUM> disclosed herein is equipped with a pressure monitoring feature in the form of gauge module <NUM>. Preferably, the gauge module <NUM> comprises the most elemental component of a mechanical gauge, simply comprised of a bourdon tube, clockwork mechanism, indicator needle, dial face and fluid communication port. Preferably, it is not equipped with any form of threaded socket, housing or protective lens and does not require use of any bonding agent to prevent rotation once installed.

Instead, preferably a gauge housing <NUM> protects the working elements of the gauge module <NUM>, and the gauge housing <NUM> is preferably provided as an integral feature of the unitary syringe body <NUM>. Preferably, as shown in <FIG>, the gauge module <NUM> is secured within this housing <NUM> by means of self-tapping retaining screws <NUM>, and a lens <NUM> is configured to snap in place onto the gauge module housing <NUM> to protect the dial face of the gauge module <NUM>.

As shown In <FIG>, the fluid displacement and pressurization device <NUM> includes a control button <NUM>, and the control button <NUM> is preferably provided at the end of the fluid displacement and pressurization device <NUM>, in the handle <NUM> of the plunger <NUM>. As will be described in more detail later hereinbelow, depressing the control button <NUM> transitions the fluid displacement and pressurization device <NUM> from micro-movement control (i.e., achieved by rotating the plunger handle <NUM>) to macro-movement control (i.e., achieved by pushing or pulling the handle <NUM> so the plunger <NUM> translates either further into or further out of the unitary syringe body <NUM>).

<FIG> provides an exploded view of the fluid displacement and pressurization device <NUM>. As shown, the fluid displacement and pressurization device <NUM> also includes a threaded member <NUM> preferably in form of a threaded cylinder, a plurality of control blades (specifically a thread control blade <NUM> and a thrust control blade <NUM>), a spring <NUM>, a pair of locking keys <NUM>, a piston <NUM>, and a sealing ring <NUM> that is preferably in the form of a rubber o-ring.

As shown in <FIG>, the piston <NUM> is engaged with the end of the plunger <NUM>, and the sealing ring <NUM> is disposed on the piston <NUM> and (as shown in <FIG>) seals against an internal wall of the barrel of the unitary syringe body <NUM>.

The unitary syringe body <NUM> is configured to retain the threaded cylinder <NUM> to guide and engage the plunger <NUM> which is operable within it. The plunger <NUM> preferably includes a fixed thread <NUM> along its entire working length.

This disclosure describes a fluid displacement and pressurization device <NUM> which includes a novel actuating mechanism for rapidly and selectively releasing or engaging a moveable threaded plunger <NUM> operable within a stationary internally threaded cylinder <NUM> within a unitary syringe body <NUM>. This mechanism is particularly suited to control a high-pressure medical syringe for purposes of pressurizing, depressurizing and evacuating therapeutic medical balloon catheters, or the like. The mechanism includes a threaded plunger <NUM> having a piston <NUM> installed at one end to traverse the barrel portion of the unitary syringe body <NUM>, a handle <NUM> with a control button <NUM> at the other end of the plunger <NUM> (i.e., opposite the piston <NUM>) and means provided within the plunger <NUM> to allow an operator to selectively engage and disengage the threaded plunger <NUM> from the threaded cylinder <NUM> by operating a control button <NUM> located within the plunger <NUM>. This mechanism provides for rapid manual reciprocation of the plunger <NUM>, locking it in one place, or precise thread controlled plunger advancement by means of plunger rotation as desired by the operator in order to either hold, displace, pressurize, depressurize or evacuate working fluid contained within the syringe.

The fluid displacement and pressurization device <NUM> provides that the plunger <NUM> is threaded and the plunger <NUM> is simply driven into engagement by the thrust control blade <NUM> which first traverses axially until its cam follower clears the cam and then moves inward toward the plunger's center to relieve plunger thread engagement. That complex motion would not be possible with a threaded insert.

Unlike the prior art syringe devices referenced in the United States patents previously cited, the fluid displacement and pressurizing inflation device <NUM> disclosed herein and shown in <FIG> utilizes a novel, user selectable plunger control mechanism that does not rely upon any form of moving half-nuts, retracting and emerging thread bearing insert strips within the plunger or expanding threaded segments. This mechanism as shown in <FIG> instead, utilizes a rigid, load bearing plunger <NUM> having a fixed thread <NUM> along its entire working length and a pair of control blades <NUM> and <NUM> whose outer edges are parallel to the longitudinal axis of plunger <NUM> and are configured to make the thread <NUM> of the plunger <NUM> selectively engageable or disengageable with the thread <NUM> in the threaded cylinder <NUM>. The control blades <NUM> and <NUM> are positioned to selectively drive, maintain or facilitate the release of threaded engagement between the thread <NUM> on the plunger <NUM> and the thread <NUM> (see <FIG>) within the threaded cylinder <NUM>.

The control blades <NUM> and <NUM> are able to either lock plunger <NUM> and its attached piston <NUM> in a desired position within the syringe barrel bore <NUM> of the unitary syringe body <NUM> and provide for thread assisted micro-movement, or release this engagement to allow macro-movement. Once the plunger <NUM> is locked (as shown in <FIG>, which is sectioned off center to better show features) into threaded engagement with the threaded cylinder <NUM>, precisely controlled micro-advancement and retraction of the plunger <NUM> becomes available by means of plunger rotation (i.e., by rotating the handle <NUM>). On the other hand, whenever the control button <NUM> is depressed (see <FIG>), the control blade <NUM> releases and prevents engagement of the plunger thread <NUM> with the thread <NUM> of the threaded cylinder <NUM> (as shown in <FIG>, which is sectioned off center to better show features) in order to facilitate free macro-movement of the plunger <NUM> (i.e., by pushing or pulling on the handle <NUM>).

The control blades <NUM> and <NUM>, generally positioned <NUM>° from one another and along the entire threaded length of plunger <NUM>, are preferably provided with tabs <NUM> and <NUM> to engage hooks <NUM> of the control button <NUM> residing within the handle portion <NUM> of plunger <NUM>. Further, as shown in <FIG>, control button <NUM> contains a spring <NUM> that bears against the handle <NUM> in order to drive the control button <NUM> outward and thereby place the control blades <NUM> and <NUM> in position to maintain threaded engagement of the plunger <NUM> with the thread <NUM> of the surrounding threaded cylinder <NUM>.

The control blades <NUM> and <NUM> each contain unique and specialized features peculiar to the purpose they serve as well as some common features, and each resides within its own dedicated and unique longitudinal guide groove within the plunger <NUM>. Specifically, as shown in <FIG>, the thrust control blade <NUM> is positioned opposite the thread <NUM> on the plunger <NUM> and operates within guide groove <NUM>. On the other hand, the thread control blade <NUM> is positioned along the center of the thread <NUM> on the plunger <NUM> and operates within guide groove <NUM>. Preferably, both control blades <NUM> and <NUM> are designed to translate transversely outward from the plunger <NUM> for a distance equal to the depth of the thread <NUM> in response to the position of the control button <NUM>.

As shown in <FIG>, the shaft of the plunger <NUM> is geometrically divisible into two zones (Z1 and Z2) by a longitudinal geometric plane (shown in <FIG> using a dashed line) disposed through the longitudinal axis, wherein a first zone (Z1) of the two zones is provided with said thread <NUM> of the plunger <NUM> and a second zone (Z2) of the two zones contains no thread.

Preferably, the control blade <NUM> is simpler than control blade <NUM> and effectively has four functions, namely: a) to assist the release of plunger thread <NUM> from threaded engagement with mating thread <NUM> on the threaded cylinder <NUM>; b) to prevent undesired re-engagement of these threads; c) to shift the rotational axis of the plunger <NUM> out of alignment with the center axis of the threaded cylinder <NUM> during disengagement from the thread <NUM> on the plunger <NUM> from the thread <NUM> in the threaded cylinder <NUM>; and d) to shift the rotational axis of the plunger <NUM> out of alignment with the center axis of the piston <NUM> that is at the end of the plunger <NUM>.

The shift of the rotational axis of the plunger <NUM> away from alignment with the center axis of the threaded cylinder <NUM> is initiated by user compression of the control button <NUM> and is accommodated by a transversely sliding coupling provided between the distal end of plunger <NUM> and piston <NUM>. This coupling consists of a "T" shaped feature <NUM> at the distal end of plunger <NUM> that engages a mating T-slot receptacle <NUM> at the proximal end of piston <NUM> (as used herein, the term distal refers to a point furthest from the operator while the term proximal refers to a point nearest the operator). The off-axis shift, driven by the thread control blade <NUM> pushing against the closed end <NUM> of piston T-slot receptacle <NUM>, is necessary because the plunger <NUM> in its entirety must be shifted transversely, by an amount equal to the depth of the plunger thread <NUM>, in order to disengage the plunger thread <NUM> from the thread <NUM> of the threaded cylinder <NUM>.

As shown in <FIG>, a lifter tip <NUM> is located at the tip of the control blade <NUM>, and is positioned to drive this transverse shift between the plunger <NUM> and the piston <NUM> whenever the lifter tip <NUM> pushes the "T" shaped feature <NUM> of the plunger <NUM> away from the closed end <NUM> of the T-slot receptacle <NUM>. This off axis shift of the plunger <NUM> relative to the position of control blades <NUM> and <NUM> must also be accommodated by the control button <NUM>, as shown in <FIG>. The control button <NUM>, while being contained within the plunger handle <NUM>, is not constrained to strict longitudinal axial movement. Instead, the control button <NUM> is configured to float within the confines of the plunger handle <NUM> and therefore remain attached to, and track along with, the control blades <NUM> and <NUM> whenever the plunger <NUM> shifts from an on-axis position with threads <NUM> and thread <NUM> engaged to an off-axis position whenever control button <NUM> is depressed to disengage the threads.

Conversely, the restoration of axial alignment between the plunger <NUM> and the center axes of the thread <NUM> and piston <NUM> occurs when thrust control blade <NUM> pushes against the tips <NUM> (see <FIG>) of thread <NUM>. Whenever the control button <NUM> is released after having been depressed, the thrust control blade <NUM> (the more complexly configured of the two control blades <NUM> and <NUM>) pushes outward, away from the center of the plunger <NUM> as shown in <FIG>, thereby withdrawing the thread control blade <NUM> inward, toward the center of the plunger <NUM>. This action shifts the center axis of the plunger <NUM> into concentric alignment with the center axis of the piston <NUM> and thread <NUM> thereby driving the thread <NUM> of the plunger <NUM> into locking engagement with mating thread <NUM> as thread control blade <NUM> withdraws toward the center of the plunger <NUM> (shown in <FIG>). Once deployed, the control blade <NUM> also serves to counter the side thrust generated by these mated threads when they are under load, such as when the plunger <NUM> is rotated to drive the piston <NUM> distally into the cylinder bore <NUM> to working pressure within inflation device <NUM>. The control blade <NUM> is preferably provided with a wide bearing surface <NUM> which delivers side thrust of the mated threads under load to the tips <NUM> of thread <NUM>. The transverse shift of the plunger <NUM> resulting from the action of the control blade <NUM> during operator release of the control button <NUM> is accommodated by the slidable coupling between T-slot receptacle <NUM> of the piston <NUM> and the T-shaped feature <NUM> that is located at the distal end of the plunger <NUM>. Because the thrust control blade <NUM> and the thread control blade <NUM> operate synchronously with one another, upon operator release of control button <NUM>, the lifter tip <NUM> simultaneously withdraws away from the closed end <NUM> of the piston T-slot receptacle <NUM>.

In order to assure the synchronous operational relationship between control blades <NUM> and <NUM>, the thread control blade <NUM> and the thrust control blade <NUM> are preferably joined to one another by interlocking features <NUM> which are provided at the ends of a series of angled fingers <NUM> and <NUM> (shown in <FIG> and <FIG>), depending from blades <NUM> and <NUM>, respectively. Interlocking of the angled fingers <NUM> and <NUM> assures that the opposing blades operate in unison whenever they are acted upon by the control button <NUM>. These joinable fingers are mated into an interlocked relationship when both control blades <NUM> and <NUM> are fully inserted into their designated guide grooves <NUM> and <NUM> and their respective angled fingers <NUM> and <NUM> meet within the array of angled receiving slots <NUM> (see <FIG>) provided for them within the plunger <NUM>. The receiving slots <NUM> are preferably configured with sufficient clearance and resilience for the interlocking features <NUM> of the angled fingers <NUM> and <NUM> to bypass one another when sufficient compressive assembly force has been applied to the outer edges of each control blade, whereby they become engaged. Once snapped together within the close-fitting confines of receiving slots <NUM>, preferably the interconnections of the angled finger's interlocking features <NUM> are maintained by the close fit of the finger receiving slots <NUM> through which they were initially inserted.

Solid webs <NUM> of plunger <NUM> that separate each of the finger receiving slots <NUM> and join guide grooves <NUM> and <NUM>, run parallel to the interlocked angled fingers <NUM> and <NUM> of control blades <NUM> and <NUM>. The proximal and distal edges <NUM> and <NUM> of the solid webs <NUM> form the boundaries of the receiving slots <NUM> and serve as ramps upon which the distal and proximal edges <NUM> and <NUM>, respectively, of the assembled angled fingers <NUM> and <NUM> are guided during movement, whenever the control blades <NUM> and <NUM> are moved longitudinally fore or aft, i.e., along the axis of the plunger <NUM>.

The angle (as shown in <FIG>) at which the interlocked angled fingers <NUM> and <NUM> are arrayed, finger angle <NUM>, determines the amount of transverse displacement obtainable by the control blades <NUM> and <NUM> to disengage the plunger thread <NUM> from the thread <NUM> in the threaded cylinder <NUM>, in response to longitudinal operator applied movement of the control button <NUM>.

Choice of this angle is driven by the output response desired for a given operator input. Finger angle <NUM> can preferably range from <NUM>° to <NUM>°, with an angle close to <NUM>° being most preferred. Positioning the angled fingers <NUM> and <NUM> and their respective finger receiving slots <NUM> at <NUM>° to the plunger's longitudinal axis, for example, will produce a translational movement of the control blades <NUM> and <NUM> that is transversely equal to the longitudinal movement of the control button <NUM> and (notwithstanding friction or the force of control button spring <NUM>) requires a button input force equal to the side thrust developed by plunger thread <NUM> while under load. An angle more acute than <NUM>°, for example one such as <NUM>° to the axis of the plunger <NUM>, would (notwithstanding friction and the force of spring <NUM>) require a user force upon control button <NUM> equal to one half of the side thrust presented by the plunger <NUM> when under load but also require twice the longitudinal movement of the control button <NUM> to obtain the necessary transverse translational movement of the control blades <NUM> and <NUM>. An angle less acute than <NUM>°, for example one such as <NUM>° to the axis of the plunger <NUM>, would (notwithstanding friction and the force of spring <NUM>) require a user force upon control button <NUM> equal to one and one half of the side thrust presented by the plunger <NUM> when under load, but also require two thirds the longitudinal movement of the control button <NUM> to obtain the necessary transverse translational movement of the control blades <NUM> and <NUM>. The angular disposition of angled fingers <NUM> and <NUM> and receiving slots <NUM> therefore, may be chosen to accommodate user expectations or requirements. Other factors impacting choice of this angle are the quantity of interconnecting angled finger necessary to locally support the thrust blade <NUM> when the plunger <NUM> is placed under a pressurization load, the width of the angled fingers <NUM> and <NUM>, and the size of webs <NUM> required to meet plunger strength requirements.

In order to allow the spring <NUM> to be light enough for comfortable use, it must be isolated from the reactionary load forces upon thrust control blade <NUM> that occur whenever plunger threads <NUM> are under working load during pressurization of the device. Therefore, as best shown in <FIG>, preferably there is a guide groove <NUM> on the plunger <NUM> which provides a series of thrust blade control cams <NUM>, and preferably thrust blade <NUM> contains a series of cam followers <NUM>, properly positioned to ride up onto and bear against mating thrust blade control cams <NUM>. This arrangement of cams and cam followers provides rigid local support to thrust control blade <NUM> at a location adjacent to bearing surface <NUM> while in contact with the thread tips <NUM> of the threaded cylinder thread <NUM>. The plunger <NUM> is thereby placed under transverse compression, which in turn eliminates the need for the spring <NUM> to bear any reaction load received by the thrust control blade <NUM> when the plunger <NUM> is placed under load during device pressurization.

During pressurization of the inflation device <NUM>, the threaded cylinder <NUM> is relied upon (through the rotational engagement of the plunger thread <NUM> within the thread <NUM> of the threaded cylinder <NUM>) to drive plunger <NUM> (and therefore also piston <NUM> and pressure seal <NUM>) distally along the syringe barrel bore <NUM>. The force of the plunger <NUM> against the threaded cylinder <NUM> resulting from this type of pressurization attempts to drive the threaded cylinder <NUM> proximally toward the operator. Therefore, means must be included to anchor the threaded cylinder <NUM> to the unitary syringe body <NUM> and transfer the resulting load of thread driven pressurization, directly to the unitary syringe body <NUM>.

To this end, locking keys <NUM> are preferably utilized to engage locking key notches <NUM> of the threaded cylinder <NUM> with corresponding locking key receiving ports <NUM> provided along the sides of the unitary syringe body <NUM>. The locking keys <NUM> are preferably configured to snap rigidly into place within the locking key receiving ports <NUM> of the unitary syringe body <NUM>. The locking keys <NUM> can also provide the ideal platform for incorporation of additional features, such as locking key mounted grips <NUM> as shown in <FIG>. Grips of this simple type (or even larger and more complex handle forms) can be included to allow users to grasp the inflation device <NUM> securely during operation and handling.

The bodies and barrels of the type of pressurizing syringes disclosed herein can be made from a variety of proprietary resins but they are most typically manufactured from commonly available, injection moldable polycarbonate resins which have high transparency, high impact resistance, superior strength compared to most other transparent resins and reasonable cost in light of their performance properties. The use of convenient self-tapping screws however, often poses design challenges for assemblies formed of these engineering resins due to internal stresses within the resin created by such fasteners. One critical weakness of polycarbonate resin is its inability to withstand the prolonged stress under load that generally accompanies the use of self-tapping fasteners. Therefore, polycarbonate resin is often an undesirable resin choice whenever the use of self-tapping screws is desired. In such instances, alternate materials often of higher cost and lower strength may be employed, but utilizing these alternatives generally forces designers to accept the less desirable compromises of material properties and cost. The design of an embodiment of the present invention (and its intended performance characteristics) make polycarbonate resin the material of choice. However, in order to allow the use of self-tapping retaining screws <NUM> to secure the gauge module <NUM>, an alternative solution is required. One option would be to mold screw threads into the gauge receiving structure <NUM> but molding small screw threads into this type of component requires very complex, costly and maintenance intensive mold construction. Another alternative (the one disclosed previously herein), is employment of a gauge module retaining insert <NUM> made from a material such as ABS, nylon, copolyester or the like including reinforced varieties of these materials for example that are tolerant of stress from self-tapping screws. This insert, when formed of such materials can be robust and unaffected by the stress of a self-tapping screw. A gauge module retaining insert <NUM>, therefore allows the use of an otherwise desirable material such as polycarbonate resin for the main body of inflation device <NUM>. Beyond providing an anchor for self-tapping screws, the gauge module retaining insert <NUM> can serve as part of the protective gauge housing. Additionally, because it is manufacturable in a variety of colors, the gauge module retaining insert <NUM> can also serve as a unique decorative and differentiating feature for inflation device <NUM>.

Benefits to the user of a device of this construction include single hand control of the plunger <NUM> for all operational manipulations including maintaining a set fill volume, rapid filling and displacement, screw thread assisted pressurization and retention of evacuation positioning during balloon depressurization. Unlike prior art devices such as the one described in <CIT>, actuation of device control by means of the plunger mechanism is easily achieved when performing any of the intended use procedures because the control button's return spring <NUM> is not called upon to bear any of the plunger's loading during pressurization. This device construction is also capable of delivering to the piston <NUM> and sustaining very high plunger force loading and yet do it with comfortable user control input. The threaded plunger design of this device provides a large surface area of thread engagement (for example, more than twice the surface area of the applicant's previously discussed prior art devices), and therefore enjoys much lower loading per unit of thread surface area. Further, because the plunger threads <NUM> are part of the plunger <NUM>, operational loads between the piston <NUM> and the device housing's threaded member <NUM> engaging the plunger <NUM> are transmitted directly by the plunger <NUM> and not indirectly through an attached component as would be the case with a threaded insert strip. Plunger loading in excess of <NUM> Newtons (<NUM> LbF) and potentially higher than <NUM> Newtons (<NUM> LbF) are thereby possible, allowing large displacement high pressure devices to be built to service the needs of new improved therapeutic procedure balloons. <FIG> relate to a second embodiment of the present invention. Specifically, <FIG> is a cross-sectional view that is similar to <FIG>, showing the device pressurized, and <FIG> is a cross-sectional view that is similar to <FIG>, showing the pressure released. <FIG> and <FIG> each show a portion of <FIG> and <FIG>, respectively, in more detail.

The embodiment shown in <FIG> is very similar to the previous embodiment, so only the differences will be described and like part numbers will be used to identify like parts. For example, like the first embodiment shown in <FIG>, the second embodiment shown in <FIG> includes thread control blades <NUM> and <NUM>, a threaded cylinder <NUM> having a thread <NUM>, a control button <NUM>, angled fingers <NUM> and a lifter tip <NUM>.

Compared to the first embodiment, the second embodiment is the preferred embodiment and includes both an improved plunger <NUM> and improved piston <NUM>. The improvements provide an improved interface which greatly enhances user control, as well as provides better plunger to piston stability for improved seal performance and allows higher plunger loading.

Compared to the first embodiment shown in <FIG>, the second embodiment shown in <FIG> provides better centralization of the plunger <NUM> within the piston <NUM> during device pressurization, particularly when the plunger's threads are engaged and loaded against the threaded cylinder element <NUM>. Better centralization serves to ensure more uniform seal loading for higher pressure seal performance. As previously disclosed, the plunger's thread <NUM> is driven transversely into engagement with the threaded cylinder <NUM> by the thrust control blade <NUM> and this thrust control blade <NUM> thereby both establishes and aligns the engaged plunger's rotational axis with the piston's central axis. The improved plunger to piston interface associated with the embodiment shown in <FIG> relives plunger side loading of the piston <NUM> by the thrust control blade <NUM> during device pressurization (shown in <FIG>), provides for reduced transitional release travel of the thread control blade <NUM> against the piston <NUM> during device depressurization (shown in <FIG>) and assures that the rotational axis of the plunger <NUM> remains parallel to the common axis of the device throughout its transverse movement. Additionally, this interface assures mutual axial alignment of the piston <NUM> and plunger <NUM> during pressurization (shown in <FIG>) and more precise alignment of the plunger <NUM> with the threaded cylinder <NUM> while they are engaged. The rigidity of the improved piston to plunger interface that is provided by the second embodiment is further enhanced when working fluid pressure, generated during device operation, compresses the individual components tightly together thereby causing them to behave as a solid unit rather than two separate components. While the improvement associated with the second embodiment involves the plunger and piston elements of the device, the functionality of these improved components still relies on interaction with components that remain unchanged with regard to the first embodiment. The basic function and operation between the two embodiments remain unchanged, as will become clear in the following discussion.

Much like the first embodiment, the second embodiment provides that plunger thread disengagement results from shifting the rotational axis of the plunger out of alignment with the center axis of the threaded cylinder <NUM> when a user compresses control button <NUM> and thereby causes the thread control blade <NUM> to extend outward and the thrust control blade <NUM> to simultaneously withdraw inward. With regard to the second embodiment, shifting the rotational axis of the plunger <NUM> with the piston <NUM> is accommodated by a transversely slidable connection between a distal tip <NUM> of the plunger <NUM> and a proximal end of the piston <NUM>. As best shown in <FIG>, the improved piston to plunger connection relies upon a distal receptacle sleeve <NUM> of piston <NUM>, wherein the receptacle sleeve <NUM> is preferably of a tubular configuration having parallel flat sidewalls <NUM> joined by semicircular walls <NUM> which receive the distal end of the plunger <NUM>. As shown, preferably each of the parallel flat sidewalls <NUM> of the receptacle sleeve <NUM> is provided with matching angularly disposed receptacle slots <NUM>. As shown in <FIG>, preferably the bottom of the receptacle sleeve <NUM> is configured with a plunger centering feature in the form of a centrally located symmetrical pair of planar faced angled ramps <NUM> at the base of the receptacle sleeve <NUM>. These angled ramps <NUM> are preferably arranged such that the minor included angle between their planar faces is ideally equal to but no less than twice the thrust face angle <NUM> of the plunger thread <NUM>.

Preferably, the distal tip <NUM> of the plunger <NUM> is equipped with a pair of flat parallel sides <NUM> to closely fit receptacle sleeve <NUM> and both are provided with angled retention barbs <NUM> to engage and retain into the angled receptacle slots <NUM> of receptacle sleeve <NUM>. Preferably, the distal tip <NUM> of the plunger <NUM> is further equipped with two angularly disposed planar surfaces as shown in <FIG>, comprising an abutment plane <NUM> and a sliding guide plane <NUM>, both being arranged to intimately align with and engage the angled ramps <NUM> within the receptacle sleeve <NUM>. These two angularly disposed planar faces are preferably oriented perpendicular to the flat parallel sides <NUM> of the plunger <NUM> and are preferably symmetrically arrayed about the rotational axis of the plunger <NUM>, wherein the axis is established when the plunger thread <NUM> is engaged with the thread <NUM> of the threaded cylinder <NUM>. The two planar end faces of the distal tip <NUM> of the plunger <NUM> are preferably further arranged with the abutment plane <NUM> adjoining the edge of the plunger <NUM> containing the thread control blade <NUM> and the sliding guide plane <NUM> adjoining the edge of the plunger <NUM> opposite the thread control blade <NUM>. The abutment plane <NUM> and the sliding guide plane <NUM> are preferably symmetrically disposed at an included angle centered upon the rotational axis of the plunger <NUM>, an angle that is ideally equal to, but no less than, the thrust face angle <NUM> of the plunger thread <NUM>. The ideal included angle between abutment plane <NUM> and the sliding guide plane <NUM> is therefore equal to, but not less than, twice the thrust face angle of the plunger thread <NUM> and in all instances identical to the included angle between the angled ramps <NUM> upon which they intimately engage.

In operation, pressing the control button <NUM> causes the thread control blade <NUM> (with lifter tip <NUM>) to extend transversely in order to release the plunger thread <NUM> from engagement with the thread <NUM> of the threaded cylinder <NUM>. The resulting transverse movement of the lifter tip <NUM> pushes the plunger <NUM> away from the semicircular wall <NUM> of the piston receptacle sleeve <NUM> as shown in <FIG>, thereby causing the end of the distal tip <NUM> of the plunger <NUM> to traverse within the piston receptacle sleeve <NUM> and move out of axial coincidence with piston <NUM>. This action assures that the thread <NUM> of the plunger <NUM> remains parallel at all times to the thread <NUM> of the threaded cylinder <NUM>. When the thread <NUM> of the plunger <NUM> is released from engagement with the thread <NUM> of the threaded cylinder <NUM>, the direction of travel of the distal tip <NUM> of the plunger <NUM> relative to the piston <NUM> is dictated by the engagement of its angled retention barbs <NUM> with the receptacle slots <NUM> and the interface of its sliding guide plane <NUM> with the face of the angled ramp <NUM> upon which it bears. Preferably, both angled retention barbs <NUM> and their respective engaging receptacle slots <NUM> are arranged to lie parallel to the sliding guide plane <NUM> of the plunger <NUM>.

The direction of travel of the lifter tip <NUM> of the thread control blade <NUM> is dictated by the angled fingers <NUM> of the thread control blade <NUM>. Therefore, whenever the thread control blade <NUM> is actuated by pressing the control button <NUM>, the lifter tip <NUM> moves distally as it moves transversely away from the rotational axis of the plunger <NUM>. Consequently, this motion of the lifter tip <NUM> attempts to shove the plunger <NUM> axially away from the piston <NUM> at the same time it is being pushed transversely away from the adjacent semicircular wall <NUM> of the receptacle sleeve <NUM>. Because the plunger <NUM> and piston <NUM> are retained to one another by the engagement of the angled retention barbs <NUM> grasping the receptacle slots <NUM>, the longitudinal motion of the lifter tip <NUM> of the thread control blade <NUM> must be accommodated by sliding axially against the adjacent semicircular wall <NUM> of the receptacle sleeve <NUM>. Friction generated by the lifter tip <NUM> of the thread control blade <NUM> sliding against the semicircular wall <NUM> increases the user input force required to depress the control button <NUM> during the initial stages of pressure release. However, due to the subtractive directionality imposed by the angled receptacle slots <NUM> and the guide plane <NUM> sliding against an abutting face of the angled ramps <NUM> as shown in <FIG>, the overall longitudinal sliding distance of the lifter tip <NUM> against the semicircular wall <NUM> is less than its overall longitudinal extension. The reduced sliding distance of lifter tip <NUM> therefore decreases the duration of frictional resistance encountered by a user pressing the control button <NUM> when effecting pressure release of the device.

Each embodiment comprises a fluid displacement and pressurization device which provides both a substantial amount of thread engagement as well as provides for single hand control for all operational manipulations including maintaining a set fill volume, rapid filling and displacement, and pressurization and retention of evacuation positioning during balloon depressurization. Each embodiment allows for the use of one hand to not only transition the device from micro-movement control to macro-movement control, but also with regard to rotating, pushing or pulling the handle of the plunger.

Claim 1:
A fluid displacement and pressurization device (<NUM>) comprising: a syringe body (<NUM>); a plunger (<NUM>) which extends into the syringe body (<NUM>), said plunger (<NUM>) comprising a thread (<NUM>) and a longitudinal axis; a piston (<NUM>) on the plunger (<NUM>) and in sealed contact with the syringe body (<NUM>); a control button (<NUM>) pressable into the plunger (<NUM>); a threaded cylinder (<NUM>) in the syringe body (<NUM>), said threaded cylinder (<NUM>) comprising a thread (<NUM>); a pair of control blades (<NUM>;<NUM>) configured to selectively engage and disengage the thread (<NUM>) of the plunger (<NUM>) with the thread (<NUM>) of the threaded cylinder (<NUM>) depending on whether the control button (<NUM>) is pressed, wherein when the thread (<NUM>) of the threaded cylinder (<NUM>) is engaged with the thread (<NUM>) of the plunger (<NUM>), the plunger (<NUM>) is rotatable to provide micro-movement of the plunger (<NUM>) relative to the syringe body (<NUM>), and wherein when the thread (<NUM>) of the threaded cylinder (<NUM>) is disengaged from the thread (<NUM>) of the plunger (<NUM>), the plunger (<NUM>) is pushable into the syringe body (<NUM>) and pullable out of the syringe body (<NUM>) to provide macro-movement of the plunger (<NUM>) relative to the syringe body (<NUM>).