|FIELD OF THE INVENTION
 This invention relates to the field of dentistry, and more
specifically to orthodontics syringe apparatus of the type having
a handle at one end and having an intra-oral nozzle at the other
BACKGROUND OF THE INVENTION
 Hand-held syringes that control the flow of a liquid and/or
air into a body cavity such as the oral cavity are known. Typically,
such a syringe is an L-shaped device having a handle, a nozzle,
and one or more finger-actuated valves that are spring-biased closed,
and whose operation controls the outward flow of liquid and/or air
from the nozzle, with the handle being connected to one or more
flexible and under-pressure fluid/air supply hoses. Often these
valves are the well known Schrader valves of the type used in pneumatic
tire stems. In this way, fluid, air, or a mixture of fluid and air
can be selectively discharged from the nozzle. The following United
States patents are examples of known prior devices. These patents
are incorporated herein by reference.
 U.S. Pat. No. 5,045,055 provides a medical/dental syringe
that includes an elongated handle having a nozzle connected to one
thereof, and having a two-hose assembly connected to the other end
thereof. The handle includes a valve body head, two flow-control
valves, and two finger actuators for the flow-control valves, to
thus selectively control the flow of water, air, or both water and
air from the nozzle. The two flow-control valves, and their O-rings,
are removable to facilitate periodic replacement. The use of VITON-brand
O-rings is suggested in order to resist the effect of repeatedly
subjecting the O-rings to high temperature. Automatic valves within
the two-hose assembly operate to seal the water hose and the air
hose when the two-hose assembly is disconnected from the handle.
 U.S. Pat. No. 5,125,835 provides a retainer assembly for
detachably mounting the multiple-conduit tip of a syringe onto a
syringe head by way of a spring-biased locking collar. The tip includes
an annular groove that receives a plurality of ball elements when
the tip is inserted into the syringe head. A movable and spring-biased
collar that is carried by the syringe head retains the ball elements
within the tip's groove, thus removably mounting the tip on the
 U.S. Pat. No. 5,199,871 provides a control valve for a dental
syringe. The control valve, having a finger-actuator, is mechanically
locked in a passageway that is provided within a syringe-head by
the operation of an O-ring that expands into a groove that is provided
in the wall of the passageway.
 U.S. Pat. No. 5,234,338 provides an autoclavable head and
handle for a dental syringe wherein the entire external housing,
including the handle, can be removed from utility supply lines,
so that the external surfaces of the housing can be autoclaved.
This function is facilitated by providing a substantially internal
quick-disconnect mechanism or cartridge whereby the flow of air
and water to the syringe is discontinued, such that the syringe's
handle, head and tip can be steam-sterilized.
 U.S. Pat. No. 5,848,893 provides that a syringe's shutoff
valves are mechanically retained in place within a syringe head
by way of a retaining pin that seats within a groove that is contained
within each of the shutoff valves, this retaining pin entering the
groove when that valve's inlet hose barb is screw-mounted onto the
syringe head. In addition, the syringe nozzle is retained in an
adapter that screw-mounts to the syringe head by way of a resilient
snap-ring that encircles the nozzle and sits within a groove that
is formed in the nozzle.
 U.S. Pat. No. 6,293,792 is similar to above-mentioned '835
patent wherein the ball-activated quick-tip-connect mechanism is
constructed so as to also seat the balls of the quick-connect mechanism
in radially-placed indentations that are carried by the tip. In
this way the balls additionally provide structural interference
against rotation of the tip.
SUMMARY OF THE INVENTION
 The present invention provides a new and useful dental syringe
that is constructed and arranged such that the internal portions
of the syringe that contain O-rings, or at least the portion of
the syringe that contains valve-associated O-rings, can be removed
from the syringe prior to the syringe being sterilized, as by autoclaving.
Thus, all O-rings that function within the syringe, or at least
the O-rings that function within the syringe's valves, are constructed
of a material such as neoprene that would likely be damaged by autoclaving.
 In order to provide an aesthetically pleasing and nicely
weight-balanced syringe, the syringe of this invention includes
(1) an internal and top-located insert, which could be made of metal,
plastic, or any other suitable material, to contain flow-channels
and the like that are required to accommodate air and/or water flow
between the syringe's two valves and the syringe's nozzle, (2) a
generally hollow and light-weight metal handle-body at whose upper
end a nozzle and the insert are located, and (3) an internally-located
and elongated light-weight, metal, and manually-removable valve
body that extends internally the length of the handle body, so as
to locate the syringe's two valves at the upper end of the handle
body and generally adjacent to and beneath the insert, and so as
to locate two hose barbs at the bottom of the handle body.
 This construction and arrangement wherein the syringe's
two normally-closed valves are placed at the top of a removable
valve body whose bottom area contains two hose barbs to which water
and air supply hoses are connected provides that when this valve
body is manually removed or disconnected from the syringe, the syringe's
two normally-closed valves are removed with the valve body, and
the two hoses are disconnected from the syringe, thus providing
a removed valve body in which the two supply hoses are sealed by
operation of the two normally-closed valves.
 When assembling the syringe of the present invention, the
syringe's insert is first inserted into an upper portion of the
handle body. An insert assembly pin is then inserted into an opening
that is provided in an upper portion of the handle body. This insert
assembly pin penetrates an opening in the insert, and thereby secures
the insert within the handle body. Two side-by-side located, virtual-center-movable,
and semi-circular valve actuating rods are carried by the insert,
and this first assembly step places the top end of these two virtual-center
valve actuating rods in positional cooperation with two O-ring-retained
valve actuating buttons that are inserted into two side-by-side
holes that are located on an upper inclined surface of the handle
 As a second assembly step, the valve body is inserted into
an opening that is located at the bottom of the handle assembly.
This second assembly step places a normally-closed air valve and
a normally-closed water valve that are located at the top of the
handle member under the insert, and in positional cooperation with
the bottom end of the two valve actuating rods. The two curved valve
actuating rods enable the linear direction of movement of the two
buttons to be inclined to the linear direction of movement of the
 As a third assembly step, a lock pin is inserted into an
opening that is provided in the upper portion of the handle assembly.
This lock pin is adapted to enter an O-ring-containing groove that
is provided in a spigot or post that is carried at the top of the
valve body. As will be apparent from the following description,
the lock pin and a release ring together lock the valve body in
the handle body.
 The syringe's nozzle is connected to a manually rotatable
release ring that encircles the outer diameter (OD) of the nozzle.
The release ring is secured to the nozzle by way of a coiled torsion
spring, one end of which is retained by the release ring. The coil
of this torsion spring grips the outer diameter (OD) of the nozzle.
That is, the inner diameter (ID) of the torsion spring is somewhat
smaller than the OD of the nozzle. The release ring is secured to
the body of the syringe by an assembly pin.
 When assembling the release ring and the nozzle, one end
of the torsion spring is retained by the release ring, and the torsion
spring is then rotated against its wound direction, to thereby produce
a spring ID that is larger than the nozzle OD. With the spring held
in this larger ID state, the nozzle is now inserted into the center
of the release ring, and the release ring is placed at a desired
location along the length of the nozzle. The torsion spring is now
released, whereupon the ID of the torsion spring decreases, thereby
causing the release ring to be rotatably mounted at this desired
position on the OD of the nozzle.
 As a fourth assembly step, the release ring is secured to
the body of the syringe with the assembly pin. The release ring
presses against the lock pin and locks the valve body in the handle.
 As the fifth and final assembly step, an end of the nozzle
is inserted into the release ring by rotating the release ring thereby
unwinding the torsion spring so as to facilitate inserting the nozzle
within the release ring and torsion spring. The release ring and
torsion spring can then be released thereby securing the nozzle
to the release ring.
 Later, when it is desired to disconnect the valve body from
the syringe, the above-mentioned release ring is rotated about 30
degrees around the nozzle. This rotation of the release ring coils
the torsion spring, such that upon a subsequent release of the valve
body, the release ring returns to its home position. This rotation
of the release ring also brings a recessed portion of the release
ring into positional coincidence with the above-mentioned lock pin.
The above-mentioned O-ring that was compressed by the lock pin now
operates to push the lock pin out of the above-mentioned groove
in the spigot that is located at the top of the valve body, the
valve body is no longer locked by the lock pin, and the valve body
can now be pulled downward and out of the handle body. Note that
since the top of the valve body carries normally closed valves,
the supply hoses that are connected to the bottom of the valve body
 As above described, syringes in accordance with this invention
include two top-located and finger-operated buttons that, when pressed,
selectively provide for the supply of pressurized air and/or water
to the syringe's nozzle. In accordance with the invention, a new
and unusual virtual-center actuator rod extends between the bottom
of these two buttons and the top of an associated valve, so as to
translate a linear force that is applied to a button into a linear
valve-opening force that is applied to an associated valve. These
two virtual-center actuator rods are arranged such that the direction
of linear movement of each button extends at an angle to the direction
of linear movement of the associated valve.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 is an exploded side view showing a syringe in accordance
with the invention;
 FIG. 2 is a vertical section view of the FIG. 1 syringe
wherein the section view is taken in a centrally located plane that
produces center-sectioning of the syringe's nozzle;
 FIG. 3 is an enlarged view of the upper portion of FIG.
 FIG. 4 is a vertical section view of the FIG. 1 syringe,
this section view being taken in a plane that lies forward of the
plane of FIG. 2, FIG. 4 showing the construction and arrangement
of one of the two valves that respectively control the flow of air
and/or water to the nozzle; and
 FIG. 5 is an enlarged view of the upper portion of FIG.
DETAILED DESCRIPTION OF THE INVENTION
 With reference to FIG. 1, reference number 10 designates
a generally L-shaped dental syringe in accordance with the invention.
 Syringe 10 includes a hollow handle body 11 that is preferable
formed of aluminum, an elongated valve body 12 preferably formed
of brass, plastic, or steel that is upward-insertable into the open
bottom of handle body 11, an internally-located insert 13 preferably
formed of brass that is located at the top of handle body 11, and
a nozzle 14 preferably formed of a metal such as stainless steel
that extends generally 105-degrees outward from the top of handle
11. It should be noted that alternative embodiments of straight
syringes with nozzles that extend approximately 180 degrees from
the top of the handle 11 also fall under the teachings of this application.
 After insert 13 has been manually inserted into an opening
that is provided at the top portion of handle body 11, insert 13
is secured in this inserted position by the operation of a manually
removable insert assembly pin 28. The insert 13 is preferably composed
of either metal or plastic.
 The bottom end of valve body 12 includes two side-by-side
located hose barbs 15, one of which is adapted to receive a hose
and a shut-off valve (not shown) that is connected to a source of
pressurized air, and the other of which is adapted to receive a
hose and a shut-off valve (not shown) that is connected to a source
of pressurized water.
 Valve body 12 also includes two internal and upward-extending
flow channels 19, one channel 19 of which is shown in FIGS. 4 and
5. The bottom end of each of these two internal flow channels 19
connects to an individual one of the two hose barbs 15, and the
top end of each of these two internal flow channels 19 terminates
at, and is closed by, an individual one of the two normally-closed
valves 16 (best seen in FIGS. 4 and 5), one valve 16 of which is
shown in an exploded position in FIG. 1. Each of the two valves
16 is spring-biased to a closed position by the operation of a coil
spring 17 that encircles a metal valve stem 18, and each of the
two valves 16 includes a valve stem O-ring 20, a valve seat 21 (best
seen in FIG. 5), and a valve O-ring 23 (best seen in FIG. 5).
 While not a limitation on the spirit and scope of this invention,
the unique construction and arrangement of syringe 10 advantageously
enables the use of neoprene O-rings throughout syringe 10, or at
least throughout the valves that are contained within syringe 10.
 As a feature of the invention, a C-clip 24 as shown in FIG.
5 is installed in each of the two valves 16 such that valve stem
18 and its various attachments, including valve seat 21 and valve
seat O-ring 22, can be forcibly extracted from valve body 12 for
 With reference to FIG. 5, each of the two valve assemblies
16 is inserted downward into an oversize or relatively large diameter
hole 51 that is formed in the top of valve body 12, thus allowing
valve seat O-ring 22 to pass the cross drilled holes 71 72 (shown
in FIG. 3) without being damaged. Moreover, a tapered-diameter portion
52 at the bottom of hole 51 is provided to compress valve seat O-ring
22 within valve body 12 in a gradual manner, as valve seat O-ring
22 reaches its final position whereat O-ring 22 settles into an
annular groove 53 that is formed in the bottom portion of hole 51.
 The bottom end of valve body 12 includes an alignment pin
27 that extends outward therefrom. The positioning of alignment
pin 27 ensures the correct physical position of valve body 12 within
handle body 11. The stop pin 74 extends up from the valve body 12
between the two spigots 31 into a matching cavity in the valve insert
13 best shown in FIG. 3.
 The top end of valve body 12 (the spigots 31) and the mating
interior surface of the insert 13 are preferably machined to provide
an o-ring 32 seal so that air and water does not leak downward through
valve 16 (shown in FIG. 1) when one or more of these valves are
opened as shown in FIG. 3. The fluid flows up through the cross
drilled holes 71 72 shown in FIG. 3. The spigots 31 carry the fluids
up into the insert 13 where O-rings 37 keep the water and air separate
while they transfer from the insert onto the separate concentric
passages in the nozzle. With valve body 12 correctly inserted within
handle body 11, the two side-by side located valves 16 that are
located on the upper end of valve body 12 are correctly aligned
with the physical position of two side-by-side located push buttons
25 that are carried by the top inclined surface 26 of handle body
11, this button/valve aligned position being best seen in FIGS.
4 and 5.
 The top end of valve body 12 carries two metal spigots or
posts 31 that individually carry a number of O-rings 32, as is best
seen in FIGS. 2 and 3.
 In addition, and as is best seen in FIGS. 1, 2 and 3, a
lock pin 46 operates to lock valve body 12 in its inserted position.
Lock pin 46 slideably extends through a hole that is provided in
handle body 11, and the end of lock pin 46 is adapted to extend
into an O-ring-containing groove 47 that is formed in a spigot 31.
 When lock pin 46 is pushed to the right, as seen in FIG.
3, the end of lock pin 46 operates to compress the O-ring 32, as
lock pin 46 is held in this pushed-position within groove 47 by
an edge 48 of release ring 42.
 With reference to FIG. 3, when release ring 42 is manually
rotated (as will be described below), a recessed cam surface (not
shown) that is machined into the edge 48 of release ring 42 is brought
into alignment with lock pin 46. The O-ring 32 that is within groove
47 now expands and pushes lock pin 46 to the left, out of groove
47, as the left end of lock pin 46 is pushed into this recessed
 With lock pin 46 in this left-ward position, where the right
end of lock pin 46 is no longer within groove 47, valve body 12
can be forcibly pulled out of handle body 11.
 The insert 13 is machined to facilitate transferring the
air and water from the spigots 31 to the separate concentric passages
33, 73 in the nozzle.
 With reference to FIGS. 1-3, the right end of nozzle 14
is releaseably mounted in an elongated linear cavity 36 that is
formed in insert 13, this releasable mounting being facilitated
by the wound torsion spring 38, as is best seen in FIG. 3.
 The torsion spring 38 has its left-end rotationally constrained
by release ring 42, and has its right end secured in a similar fashion
to the insert 13, such that forcible rotation of the release ring
42 uncoils the wound spring 38 and allows the nozzle 14 to be inserted.
When the force rotating the release ring 42 is removed the torsion
spring 38 acts to return to its coiled position forcing the release
ring 42 back to its home position. As the torsion spring 38 recoils,
its ID is reduced claming the nozzle 14 and holding it in place
axially and to a lesser extent rotationally.
 The relaxed ID of torsion spring 38 is somewhat smaller
than the OD surface 40 of nozzle 14. When release ring 42 is in
its not-rotated or home position, as seen in FIG. 3, torsion spring
38 relatively tightly grips the OD surface 40 of nozzle 14.
 In an operation to manually remove valve body 12 from handle
body 11, manual rotation of release ring 42 for about 30 degrees
allows the lock pin 46 for the valve body 12 to retract into the
chamber on the outer edge of the release ring 42 thereby releasing
the valve body 12. In addition, the rotation of the release ring
42 30 degrees also causes the nozzle 14 to release. The ability
to release both the nozzle 14 and the valve body 12 with a rotation
of the release ring 42 is a design feature that simplifies operation
of the syringe and manufacturing. With release ring 42 held in this
30-degree-rotated position, lock pin 46 moves to the left in FIG.
3, the right end of lock pin 46 is thus withdrawn from groove 47,
and valve body 12 can be manually pulled out of the bottom of handle
 That is, release ring 42 functions in its 30-degree-rotated
position to cause lock pin 46 to be withdrawn from the groove 47
that is formed in a spigot 31 that is carried at the top of valve
body 12, to thus enable valve body 12 to be manually withdrawn from
handle body 11.
 As perhaps best seen in FIG. 3, release ring 42 sits in
an opening 56 that is formed at the side and top of handle body
11. The ID of release ring 42 freely rotates on the OD 57 of insert
13, and the inside face of release ring 42 freely rotates on the
front face 58 of insert 13.
 Release ring 42 is secured to handle body 11 by a release
ring assembly pin 59 which is held by handle body 11 and which mates
with a U-shaped groove 60 that is formed in a portion of the OD
surface of release ring 42.
 One end of U-shaped groove 60, which can be called the home
position end, cooperates with release ring assembly pin 59 to act
as a home-stop for release ring 42, as torsion spring 38 operates
to hold this end of U-shaped groove 60 against release ring assembly
 When release ring 42 is rotated about 30 degrees, as above
described, the opposite end of U-shaped groove 60 engages release
ring assembly pin 59 and acts as a rotation-stop that prevents damage
to torsion spring 38. It should be noted that in reality the valve
body 12 is effectively released when the release ring 42 is rotated
only 7 degrees and the remainder of the rotation is to allow the
ring to unwrap enough to release the nozzle 14. Likewise, the syringe
can be manufactured so as to allow the valve body 12 and or the
nozzle 14 to effectively release at almost any angle of rotation
of the release ring 42.
 As described, the above-mentioned 30 degree rotation of
release ring 42 enables valve body 12 to be manually removed from
handle body 11. With reference to FIG. 3, this 30 degree rotation
of release ring 42 additionally uncoils the tension spring 38 such
that the nozzle 14 can be removed from the insert 13.
 That is, when release ring 42 is in its home position, lock
pin 46 operates to lock valve body 12 in handle body 11, and release
ring assembly pin 59 operates to lock release ring 42 to handle
body 11. However, when release ring 42 is in its 30 degree rotated
position, both valve body 12 and nozzle 14 can be manually removed
from handle body 11.
 The construction and arrangement of syringe 10 facilitates
the removal of valve body 12 and its two top-located valves 16 by
providing that the two valves 16 are actuated remotely and by forces
that extend at an angle to the direction of linear movement of the
two valve stems 18.
 In order to optimize this remote valve operation by buttons
25, and in order to achieve the lightest possible button action
or force, the invention provides an actuate-shaped or semi-circular
shaped actuating rod 65 for each of the button/valve pairs, as is
best seen in FIGS. 4 and 5.
 In accordance with the invention, the semi-circular movement
of each of the two actuating rods 65 is about a virtual-center-of-rotation
that is indicated as virtual-center 66 in FIG. 5.
 Since the semi-circular movement of actuating rods 65 occurs
about this theoretical rotational center 66, the construction and
arrangement of the invention places no physical limitations on the
location of virtual-center 66, and the actuating rods 65 can operate
through a range of angles, and can provide a range of forces-ratios,
with very little accompanying friction.
 This end result is accomplished by placing each of the two
semi-circular actuator rods 65 in a semi-circular track 67 that
is formed in insert 13. Preferably each of the two actuator rods
65 is supported and retained in its semi-circular track 67 by one
or more metal ball bearings 68 that run in a recess 69 that is formed
in each of the semi-circular tracks 67 and a corresponding recess
70 that is formed in each of the two actuator rods 65.
 The length of the semi-circular movement of each of the
two actuator rods 65 about virtual center 66 (for example about
30 degrees) is limited by ball bearing 68 engaging the end of one
or both of the two semi-circular recesses 69 and 70, and in FIG.
5 it is seen that while ball bearing 68 has engaged the top end
of recess 70, further downward movement of actuator rod 65 is possible,
until ball bearing 68 engages the bottom end of recess 69.
 In accordance with the spirit and scope of the invention,
and particularly when friction is not a concern, any other form
of actuator rod support, including but not limited to disc, roller,
or tongue-and-groove, that is capable of retaining actuating rods
65 for semi-circular movement about virtual center 66 can be utilized.
 Placement of virtual center 66 is generally dictated by
the desired force-ratio that is achieved at a given point along
the semi-circular stroke of an associated valve-actuating-button
25. Placement of virtual center 66 can be such that this force-ratio
will increase, or it will decrease, as a button 25 travels, depending
upon the location of virtual center 66. Further force ratio refinement
can be achieved by shaping the two ends of actuating rods 65 whereat
the rods physically contact a button 25 or a valve stem 18.
 In one embodiment of the invention, a force-ratio was provided
wherein the ratio of the button-force to the valve-actuating-force
was 0.74-to-1 when button movement first began, and was 1-to-1 at
the end of the button's semi-circular stroke.
 In another embodiment of the invention each of the two actuator
rods 65 moved through a semi-circular angle of 45 degrees around
virtual center 66. In this embodiment of the invention the above-mentioned
force-ratio varied as shown in the following Table-1.
1 TABLE 1 Angle of movement Force-ratio 0 degrees 0.77-to-1 7.5
degrees 0.77-to-1 15.0 degrees 0.77-to-1 16.0 degrees 0.77-to-1
22.5 degrees 0.77-to-1 30.0 degrees 0.77-to-1 31.0 degrees 1.28-to-1
37.5 degrees 1.28-to-1 45.0 degrees 1.28-to-1
 Note that in the above embodiment of the invention the force-ratio
changes abruptly between 30 degrees and 31 degrees of movement,
this being an example of the versatility of the invention.
 In yet another embodiment of the invention wherein each
of the two actuator rods 65 moved through a semi-circular angle
of 45 degrees around virtual center 66 the above-mentioned force-ratio
varied as shown in the following Table-2.
2 TABLE 2 Angle of movement Force-ratio 0 degrees 1.0-to-0.95 7.5
degrees 1.0-to-0.97 15.0 degrees 1-to-1 16.0 degrees 1-to-1 22.5
degrees 1.0-to-1.02 30.0 degrees 1.0-to-1.05 31.0 degrees 1.0-to-1.05
37.5 degrees 1.0-to-1.07 45.0 degrees 1.0-to-1.10
 While this invention has been described with reference to
certain specific embodiments and examples, it will be recognized
by those skilled in the art that many variations are possible without
departing from the scope and spirit of this invention. The invention,
as defined by the claims, is intended to cover all changes and modifications
of the invention which do not depart from the spirit of the invention.
The words "including" and "having," as used
in the specification, including the claims, shall have the same
meaning as the word "comprising."