Cylinder pump having controllable piston/drive detachment

A cylinder pump having a controllable piston/drive detachment is disclosed that can engage or disengage a piston rod using a solenoid. Most any type of drive can be used. The cylinder pump could have one or more cylinders. Each cylinder and piston rod has quick connect and disconnect mountings. The cylinder pump could be a syringe pump or drive.

FIELD OF THE INVENTION 
This invention is directed to the field of fluid handling, and more 
particularly, to a novel cylinder pump having a controllable piston/drive 
detachment which the user can select meter and deliver fluid from one or 
more cylinders which are quick connect/disconnect. 
BACKGROUND OF THE INVENTION 
This invention relates to fluid handling. There are applications where it 
is advantageous to engage or disengage piston rods to control the flow of 
a fluid. There are also applications where more than one fluid is needed 
to be metered and delivered at a time. A few such applications are in 
sample preparation instruments for blood, serum and urine. Reagents and 
other chemicals are added to the sample to prepare it for analysis. 
Heretofore, there were two common systems to add more than one fluid to 
the sample. The first means was to have a separate motor and pump for each 
fluid to be added. This provided a lot of flexibility but at a high price. 
It also made the apparatus complex, large and heavy. The second means was 
to use one motor and pump but to equally stroke a mechanically connected 
bank of syringes. The diameter of the syringes in the bank could be varied 
so they could deliver different flow rates or volumes for the same stroke. 
This costs less than the first means but is much less flexible and makes 
it difficult and time consuming to vary which fluids are being delivered 
and in what volumes because syringes must be manually changed or removed. 
Accordingly it would be desirable to select which syringes will deliver 
fluid, to easily and quickly change the syringes and to have a smaller, 
less complex and lower cost drive means. 
SUMMARY OF THE INVENTION 
The novel fluid handling apparatus of the present invention is a cylinder 
pump having a controllable piston/drive detachment with means to 
accurately stroke one or more pistons at a time while keeping the fluids 
separate. There is only one drive means required and neither the 
mechanical, electrical, electronic nor software designs are complex. The 
simplicity of the design will result in a lower cost but equally accurate 
system as compared to the state of the art. The volume delivered is simply 
the stroke times the area of the syringe bore. Only one of many possible 
embodiments is described in detail in this specification, The major 
components of the preferred embodiment consists of a stepper motor, lead 
screw, multiple cylinders/pistons or syringes, a solenoid for each 
cylinder/piston or syringe and a controller. Different diameter 
pistons/cylinders and syringes can be used to vary the flow rate for the 
same stroke and the present invention allows quick and easy replacement 
using standard disposable or laboratory syringes. 
An actual application of this embodiment is in the field of flow cytometry 
where reagents and other chemicals are added to a blood sample to prepare 
it for analysis. For example, blood is put into one or more test tubes 
that will later be used in an analysis machine. Another syringe is used to 
add a reagent to the test tube(s) to lyse the red blood cells. Still 
another syringe is used to add another reagent depending on what tests are 
to be performed. All these syringes are driven by the same motor through a 
block that mounts or houses solenoid valves to engage or disengage 
syringes as required. Therefore during an actuation of the block by the 
stepper motor and lead screw the user can specify having all, some or none 
of the syringes selectively stroked to deliver only what fluid and in what 
quantity it is required. This provides the user previously unavailable 
flexibility with simple, compact and low cost hardware and software.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 is a front view of a four syringe pump apparatus 10 incorporating 
certain aspects of the present invention. Said apparatus can be built for 
one or more syringes 12 with top orifice 13 and piston rod 15. A piston 
and cylinder could replace a syringe 12 in a different embodiment. FIG. 2 
is a substantially cut away view of apparatus 10 taken along cut lines 
2--2. The frame 16a is for mounting the various components that remain 
fixed to the frame 16a. Block 18a moves relative to frame 16a with the 
drive motion provided through slot 20 and guided by shaft 14 shown in FIG. 
1 via connector 2 2 attached to the lead screw 24 shown in FIG. 2. A 
clearance is maintained between block 18a and frame 16a. Continuing to 
refer to FIG. 2, the means of being able to independently engage or 
disengage rod pins 28 make it possible to stroke all, some or none of the 
rod extensions 30. Rod extensions 30 can be square, circular or any other 
cross-section. Rotation will be prevented if other than a circular 
cross-section is used. Rotation can be also prevented by use of a 
longitudinal slot in rod extensions 30 and aligned fixed pins in block 18a 
that slide in longitudinal slots in rod extensions 30. Non-rotation during 
operation will assure that rod extensions will always be in an orientation 
for easy removal of syringes 12. The invention relies on the friction 
between the piston 19 and cylinder wall 23 being greater than between the 
rod extension 30 and the rod extension receiving hole 51. This is 
necessary so piston 19 stays in position when corresponding rod extension 
30 is not engaged and moving with the block 18a. This is not a problem 
since there must be a very small clearance to prevent leakage between 
piston 19 and cylinder wall 23. The clearance between rod extension 30 and 
rod extension receiving hole 51 can be relatively large. In this 
embodiment, rod pins 28 are moved by electrical solenoids 26. The 
individual syringes 12 can contain the same or different fluids and can be 
the same or different diameters. Different diameter syringes 12 will vary 
the volume delivered for the same stroke. Quick disconnect screw 36, mount 
37 and cavity 38 on rod extension 30 allow the user to quickly and easily 
change syringes 12. This embodiment uses manual style syringes 12 with a 
piston rod end in the shape of a disk. The invention with minor 
modifications can use instrumentation style syringes 12 that have a hole 
perpendicular to the direction of travel to fit over a pin on the rod 
extension top end. This quick connect and disconnect feature is also 
applicable to a piston and cylinder combination. Referring to FIG. 5, 
shown is one possible embodiment of quick connect and disconnect mount 37, 
a small rectangular structural piece with two concave sides that provide 
clearance for screw 36 shown installed in FIG. 1. Still referring to FIG. 
1, mount 37 is rigidly attached to the tip of the syringe 12 through hole 
39 shown in FIG. 7 and if using a threaded adapter remains with syringe 12 
when it is removed. The syringe 12 can be as easily removed upwards as 
outwards. Mount 37 and support 35 could be built to slide in and out and 
up and down to adapt to different size syringes. Referring to FIG. 1, 
valve 40 could be included in the assembly to minimize loss of fluid when 
the tube 42c is disconnected and to allow continuous operation by 
aspirating fluid via tube 42a and evacuating and metering fluid out via 
tube 42b. Valve 40 could include pinch valves, check valves, or actuated 
valves to direct the flow. A multiple syringe pump apparatus 10 would 
preferably use standard length syringes 12 in order to provide greatest 
flexibility, modularity and therefore speed of changeover. Referring to 
FIG. 2, the drive means 44 can accurately move in increments. The drive 
means 44 can be linear, rotary, electrical, hydraulic or pneumatic. Shown 
is a common industry means to drive a syringe pump using a rotary stepper 
motor for drive means 44 with its rotary motion being translated into 
linear motion by lead screw 24 through belt 46 and pulleys 48a and 48b. 
One manufacturer uses gears instead of pulleys. The travel of lead-screw 
24 can be measured by the sensor 50 that sends a signal to a controller 52 
via wires 53. The controller 52 uses this signal to adjust the travel to 
improve the accuracy of the stroke length and therefore improve the 
accuracy of the delivered volume. This accuracy correction is desirable 
due to motor inaccuracy, belt drive inaccuracy and lead screw backlash. 
Controller 52 also converts manual user commands into signals to the drive 
means 44. Block 18a is manufactured with cavities to contain certain 
components. Shown in FIG. 2, solenoid 26 is rigidly installed in a 
cylindrical hole in block 18a and receives electrical signals from 
controller 52 to move link 54 through solenoid pin 27. When assembling 
this apparatus, link 54 is installed through groove 55 in block 18a. Link 
pin 57 attaches link 54 to block 18a. When solenoid 26 is energized, link 
54 pivots around link pin 57 and overcomes the resistance of pin spring 56 
to move rod pin 28 to engage rod extension 30. Another embodiment could 
show solenoid 26 perpendicular to the travel direction of block 18a. In 
this embodiment, solenoid 26 could engage rod extension 30 directly 
without the need for link 54. The disadvantage to the perpendicular 
arrangement is that block 18a has to be larger in depth than in the 
embodiment shown. Alternatively, rod pin 28 could be actuated by air or 
fluid conveyed in passageways in a block similar to block 18a and valves 
(not shown) that direct the air or fluid only to the pin bores that 
correspond to the syringes 12 to be stroked. There is no need to provide 
an airtight seal between the bore and the rod pin 28. For example, a small 
clearance will not leak enough air to prevent the rod pin 28 from moving 
with normal laboratory air pressure. In the embodiment shown in FIG. 2, 
pin spring 56 holds rod pin 28 disengaged from rod extension 30 when there 
is no signal being sent to solenoid 26. When rod pin 28 is engaged, it 
fits into the slot or hole in rod extension 30 which slides in rod 
extension receiving hole 51 parallel and next to corresponding solenoid 
26. There are at least three other arrangements to use solenoid 26 to 
engage rod extension 30. Solenoid 26 could be mounted parallel but below 
rod extension 30 with pin spring 56 in line with the axis of solenoid 26 
but on the other side of a link similar to link 54. In another variation, 
solenoid 26 could be mounted parallel and next to rod extension 30 with 
spring 56 in line and on the same side of a pivoting link similar to link 
54. Still another variation could have solenoid 26 mounted in line and 
below rod extension 30. Other applications might not use solenoid 26 at 
all to engage and disengage rod pin 28 but use air pressure as described 
above. Even a manual means could be used to engage and disengage rod 
extension 30. Manual means of engagement and disengagement could be used 
for a very low cost version of the pump apparatus 10. A standard quarter 
turn spring loaded fastener with an elongated pin could be mounted to the 
vertical surface of block 18a and used to manually engage or disengage rod 
extension 30. Another alternative is to use an over center latch that 
would rotate into engagement with rod extension 30. All these arrangements 
are practical and their use depends on the particular needs of the 
application. 
There are a number of variations possible to reduce the size and cost of 
the pump apparatus shown in FIGS. 1 and 2. A block similar to block 18 a 
could be fabricated with aligned and threaded holes that engage directly 
with lead screw 24 eliminating connector 22. 
FIG. 3 is a bottom view of a drive means using a rack 58 and a pinion 60 to 
eliminate the need for lead screw 24, connector 22, belt 46, pulleys 48 
and possibly sensor 50 shown in FIG. 2. Block 18b would be similar to 
block 18 a except it would have channel 62 running the length of block 18b 
to mount rack 58 and provide clearance for pinion 60. The drive means 44 
could also be mounted perpendicular to the direction shown in FIG. 3 and 
drive the block 18b through frame 16b. Frame 16b would be similar to frame 
16a except for the mounting of drive means 44 and controller 52 in FIG. 2. 
A direct drive arrangement like this may be accurate enough without a 
closed loop feedback signal. If it is not accurate enough without a 
feedback signal, a linear transducer 64 could be mounted in a receiving 
hole next to shaft 14. This arrangement would significantly reduce the 
complexity and size of pump 10 shown in FIGS. 1 and 2. 
The different drive means shown in FIG. 3 is not an entirely new drive 
means but now becomes attractive for this application because of the 
addition of sliding block 18b in FIG. 3. Now provided is a surface to 
mount the rack 58 in FIG. 3. This arrangement would certainly provide a 
less complex, smaller size and lower cost apparatus than is currently 
being used for multiple syringe pumps 10. 
OPERATION OF INVENTION 
Apparatus 10 in FIGS. 1 and 2 is operated based on input from the user. The 
user commands can be inputted through a keypad, switches, touch sensitive 
screen, mouse, keyboard or other user interface device (not shown). In the 
embodiment shown, the cycle starts at the top of the stroke placing the 
large diameter coupling elements of rod extensions 30 in contact with 
block 18a. Having the large diameter coupling elements of rod extensions 
in contact with block 18a is a simplified means to align the holes or 
slots in rod extensions 30 with pins 28. Holes and slots could be put in 
other locations also so pins 28 could be engaged at different or multiple 
positions. Syringes 12 can be empty, partially full or entirely full at 
the start of a cycle. When pins 28 are aligned with the holes or slots in 
rod extensions 30, controller 52 sends signals to energize selected 
solenoids 26. Controller 52 is used to send a signal to rotate drive means 
44 a certain amount either to align pins 28 with slots in rod extensions 
30 or to start a cycle. The drive means 44 rotation causes lead screw 24 
to rotate and connector 22 to linearly travel a proportional amount. An 
optional sensor 50 can monitor the actual linear travel and provide a 
feedback signal through wires 53 to controller 52. Based on the feedback 
signal, controller 52 can adjust the rotation of drive means 44 in order 
to have a precise amount of travel. Connector 22 drives block 18 a that 
houses solenoids 26. Any rod extensions 30 that have not had their 
corresponding solenoids 26 engaged will not move with the block 18a in the 
aspiration mode. If the cycle started at the top of the stroke, disengaged 
rod extensions 30 will also not move in the dispense mode because due to 
friction they will hang from the fully compressed syringe. To disengage 
solenoid 26, no electrical power is sent to solenoid 26 and spring 56 
retracts rod pin 28. When block 18a travels, rod extension 30 
corresponding to disengaged rod pin 28 will not stroke if the cycle 
started at the top of the stroke. To engage solenoid 26, electrical power 
is sent from the controller 52 so solenoid 26 causes the rod pin 28 to 
overcome the force of spring 56 and engage rod pin 28 into the hole or 
slot on rod extension 30. Engaged solenoids 26 cause their corresponding 
rod extensions 30 to travel with block 18a. The signal to stop drive means 
44 comes from controller 52 using original input parameters and the sensor 
feedback signal. The sequence can be repeated with the same or different 
parameters. The remaining volume of fluid in each syringe 12 can be sensed 
directly or derived by knowing how much was put into the syringe 12 at the 
start and how much has been used. This can be a manual calculation or 
programmed into controller 52. The drive means 4 4 has the capability to 
travel in either direction so it can return block 18a to its lower most 
position where full syringes 12 can be installed. There is also an option 
to install and use valve 40 to supply fluid from a reservoir (not shown) 
connected to tube 42a and pump a metered amount of fluid through tube 42b. 
Thus the reader will see that the invention described above provides a 
simple, relatively small, low cost but equally flexible alternative to 
using a separate drive motor for each syringe 12. It provides better 
accuracy and inherent safety than an apparatus that operates on high 
pressure compressible fluids. The invention also keeps the fluids pumped 
by each syringe 12 completely separate thereby eliminating the possibility 
of cross-contamination. Also included is a quick connect and disconnect 
feature to change syringe 12 sizes or fluids being pumped. In a multiple 
syringe pump application, standard syringe sizes from existing 
manufacturers can be used without modifications or adjustments to the 
apparatus 10. 
Although the invention was developed for and the embodiments shown describe 
a multiple syringe pump having controllable piston/drive detachment, the 
teachings of the invention are not to be considered so limited. Rather, 
the teachings of the invention apply to any type of cylinder and piston in 
either the evacuation or aspiration pump mode. Many other variations are 
possible and a few were described above. For example, the rod extensions 
30 could be engaged in a number of ways using solenoid 26 or in a lower 
cost machine even actuated by hand. There could be any number of syringes 
12 used in an application of this invention and in any geometry. For 
example, multiple cylinders 23 or syringes 12 in FIG. 2 could be arranged 
in a circular fashion and the principles could still be applied. The 
apparatus 10 could be operated in any orientation. Accordingly, the scope 
of the inventions should be determined not by the embodiments illustrated, 
but by the appended claims and their legal equivalents.