Valve assembly with spool for proportional control of fluid flow and ventilator

Abstract

The valve assembly includes a conduit having a first end and a second end, and two control valves. Each valve has three ports and a spool for selectively adjusting the rate of fluid flow through two of the ports. The first ports of the valves are for connection to an intake port or an output port of a pump, respectively. The second ports of the valves are connected to the second end of the conduit to draw fluid from or supply fluid to the conduit, respectively. The valves may be included in a ventilator to control the application of variable pressure to the exterior surface of the lungs within a sealed chamber to breathe into the lungs. TIFF2025531573000006.tif96128

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 412,664, filed October 3, 2022, the entire contents of which are incorporated herein by reference.

[0002] INCORPORATION BY REFERENCE Any patents, patent publications, journal publications, or other documents cited herein are expressly incorporated herein by reference in their entirety.

[0003] Technical Field The present disclosure relates generally to valve assemblies and ventilators, and more particularly to valve assemblies and ventilators for ex vivo ventilation of resected lungs. [Background technology]

[0004] background To use a resected donor lung for transplantation, it may be necessary to perfuse and ventilate the resected lung ex vivo to restore or preserve its functionality before the transplant procedure, or to assess or evaluate its quality or suitability for transplantation.

[0005] Various ventilation techniques have been proposed, including negative pressure ventilation (NPV) and related devices. In NPV, the lungs may be ventilated using external negative pressure (i.e., below atmospheric pressure) around the lungs so that they naturally fill with air (or gas) at or near atmospheric pressure. For example, a gas such as air may be supplied to the airways of the lungs at positive pressure (above atmospheric pressure), and external negative pressure may be maintained around the lungs.

[0006] However, it would be desirable to provide improved devices and systems for implementing NPV and other ventilation methods or techniques. Summary of the Invention

[0007] overview In one aspect of the present disclosure, a valve assembly is provided comprising: a first conduit having a first end and a second end; and first and second control valves, each control valve having a first port, a second port, and a third port, and each control valve further comprising a spool configured to selectively adjust a rate of fluid flow through the second and third ports of the respective control valve, wherein the first port of the first valve is configured to connect to an intake port of a pump, the second port of the first control valve is configured to connect to the second end of the first conduit to draw fluid from the first conduit, the first port of the second control valve is configured to connect to an output port of the pump, and the second port of the second control valve is configured to connect to the second end of the first conduit to supply fluid to the first conduit.

[0008] In various embodiments, the valve assembly described in the preceding paragraph may include one or any combination of the following features: The control valves may include an actuator for actuating the spool of the respective control valve; The actuator may include a servomotor; The spool of at least one of the first and second control valves is a sliding spool, and the actuator of the at least one control valve is a linear actuator; The spool of at least one of the first and second control valves is a rotary spool, and the actuator of the at least one control valve is a rotary actuator; The linear actuator of the at least one control valve includes a drive shaft coupled to the sliding spool of the respective control valve for positioning the sliding spool; The linear actuator of the at least one control valve includes a proximity sensor for determining a position of the drive shaft of the respective control valve; The actuator of the at least one control valve includes a controller for controlling movement of the drive shaft of the respective control valve based on an output signal from the proximity sensor of the respective control valve. The drive shaft of the linear actuator of at least one control valve and the sliding spool of the respective control valve are axially aligned along the axis of the drive shaft. The drive shaft of the linear actuator of at least one control valve includes a guide rod configured to maintain the axial alignment of the drive shaft of the respective control valve. The linear actuator of at least one control valve includes a connector coupled to the drive shaft and the sliding spool of the respective control valve. The drive shaft of the linear actuator of at least one control valve and the sliding spool of the respective control valve are vertically stacked.At least one control valve comprises a housing including a cylindrical bore extending between opposite ends, a first port for the respective control valve located on a first side of the bore, and a second port and a third port for the respective control valve located on a second side of the bore; a spool for each control valve is slidable within the bore and comprises a laterally extending conduit including a first opening facing the first side of the bore and a second opening facing the second side of the bore; the first opening is sized and positioned to allow fluid communication with the first port; and the second opening is sized and positioned to selectively allow fluid communication with the second and third ports by sliding the spool within the bore. The valve assembly may comprise a three-way connector at the second end of the first conduit for connecting the second end of the first conduit to the second port of the first valve and the second port of the second valve, respectively. The three-way connector may comprise a three-way valve, a T-junction, or a Y-junction.

[0009] In another aspect, a ventilator is provided that includes a sealed chamber for containing a lung within the sealed chamber, the sealed chamber having a pressure port; and a first fluid system for applying a variable first pressure to an exterior surface of the lung within the sealed chamber through the pressure port to cause the lung to breathe. The first fluid system includes a first pump having an inlet port and an outlet port. A valve assembly as described herein is connected to the inlet port and the outlet port of the first pump. A first end of a first conduit of the valve assembly is sealingly connected to the pressure port of the sealed chamber.

[0010] In various embodiments, the ventilator described in the preceding paragraph may include one or any combination of the following features: The ventilator may further include a second fluid system for applying and maintaining a second pressure in the airways of the lung; wherein the second fluid system may include a second conduit having a first end and a second end, the second end of the second conduit being connectable to the trachea of ​​the lung through a sealed chamber. The second fluid system may further include a second pump for supplying pressurized fluid to the second conduit and for maintaining the second pressure in the second conduit. The ventilator may further include a control system configured and connected to control the first and second fluid systems to breathe into the lungs. The control system may include sensors for sensing pressure and fluid flow in the first and second conduits; and a processor for processing the sensed pressure and fluid flow and for determining the pumping speed of each pump and the rate of fluid flow through the second and third ports of the respective control valves. The ventilator may further include a third conduit connecting a third port of the second control valve of the first fluid system to the second conduit of the second fluid system; and a third control valve in the third conduit for regulating fluid flow from the first control valve to the second conduit through the third conduit. Each of the first pump and the second pump may include a blower. The ventilator may include a fluid filter in each of the first and second conduits. The ventilator may include a fluid filter coupled to a third port of at least one of the first control valve and the second control valve. The ventilator may include a fluid filter coupled to an input port of the second pump.

[0011] Other aspects, features, and embodiments of the present disclosure will become apparent to those skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0012] The accompanying drawings illustrate the following exemplary embodiments: [Figure 1] FIG. 1 is a block schematic diagram of an apparatus for ventilating lungs, according to an exemplary embodiment of the present disclosure. [Figure 2A] 2 is a schematic diagram of a valve assembly suitable for use in the device of FIG. 1 according to an exemplary embodiment of the present disclosure. [Figure 2B] 2B is a schematic diagram of a valve suitable for use in the valve assembly of FIG. 2A or the device of FIG. 1 according to an exemplary embodiment of the present disclosure. [Figure 3] FIG. 2 is a block schematic diagram of an exemplary embodiment of the apparatus of FIG. 1. [Figure 4] FIG. 4 is a schematic diagram of the device of FIG. 3 showing airflow during inspiration. [Figure 5] FIG. 4 is a schematic diagram of the device of FIG. 3 showing airflow during exhalation. [Figure 6A] FIG. 2C is a more detailed schematic diagram of the valve of FIG. 2B. [Figure 6B] 6B is a cross-sectional schematic view of the valve disc of the exemplary embodiment of the valve of FIG. 6A. [Figure 6C] 6B is a cross-sectional schematic view of a valve disc of another exemplary embodiment of the valve of FIG. 6A. FIG. [Figure 6D] 6B is a cross-sectional schematic view of a valve disc of a further exemplary embodiment of the valve of FIG. 6A. [Figure 7A] FIG. 1 is a front perspective view of a three-way proportional valve according to an exemplary embodiment of the present disclosure. [Figure 7B] FIG. 7B is a rear perspective view of the valve of FIG. 7A. [Figure 8A] FIG. 7B is an exploded front view of the valve of FIG. 7A. [Figure 8B] FIG. 7B is an exploded rear view of the valve of FIG. 7A. [Figure 9A] 7B is a top cross-sectional view of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 9B] 7B is a top cross-sectional view of the valve of FIG. 7A taken along its axis with the spool in different positions. [Figure 9C] 7B is a top cross-sectional view of the valve of FIG. 7A taken along its axis with the spool in different positions. [Figure 10A] 7B is a cross-sectional view of the right or left side of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 10B] 7B is a cross-sectional view of the right or left side of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 10C] 7B is a cross-sectional view of the right or left side of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 10D] 7B is a cross-sectional view of the right or left side of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 10E] 7B is a cross-sectional view of the right or left side of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 10F] 7B is a cross-sectional view of the right or left side of the valve of FIG. 7A along its axis with the spool in different positions. [Figure 11A] FIG. 10 is a front perspective view of another three-way proportional valve according to one aspect of the present disclosure. [Figure 11B] FIG. 12B is a front exploded view of the valve of FIG. 12A. [Figure 12] Figure 12A is a top cross-sectional view of the valve of Figure 11A along its axis, and Figure 12B is a right-side cross-sectional view of the valve of Figure 11A along its axis. [Figure 13] Figure 13A is a left side view of the valve of Figure 11A, showing the spool and actuator separated, and Figure 13B is a rear view of the valve of Figure 11A, showing the spool and actuator separated. [Figure 14] FIG. 10 is a top perspective view of another three-way proportional valve according to a further aspect of the present disclosure. [Figure 15] FIG. 15 is an exploded view of the valve of FIG. 14. [Figure 16A] FIG. 15 is a top cross-sectional view of the valve of FIG. 14 taken along its axis. [Figure 16B] FIG. 15 is a left-side cross-sectional view of the valve of FIG. 14 along its axis. [Figure 16C] 15 is a right-side cross-sectional view of the valve of FIG. 14 taken along its axis. [Figure 16D] FIG. 16 is an enlarged view of a portion of the valve of FIG. 15. [Figure 17] FIG. 10 is a top perspective view of another three-way proportional valve according to another aspect of the present disclosure. [Figure 18A]FIG. 18 is an exploded view of the valve of FIG. 17. [Figure 18B] FIG. 18 is a cross-sectional view of the valve of FIG. 17. [Figure 19] Figure 19A is a top cross-sectional view of the valve of Figure 17 taken along an axis, and Figure 19B is a right-side cross-sectional view of the valve of Figure 17 taken along an axis. [Figure 20] FIG. 10 is a front perspective view of another three-way proportional valve according to a further aspect of the present disclosure. [Figure 21] FIG. 21 is a front exploded view of the valve of FIG. 20. [Figure 22A] 21A-21B are top cross-sectional views of the valve of FIG. 20 taken along line AA-AA with the spool in different positions. [Figure 22B] 21A-21B are top cross-sectional views of the valve of FIG. 20 taken along line AA-AA with the spool in different positions. [Figure 22C] 21A-21B are top cross-sectional views of the valve of FIG. 20 taken along line AA-AA with the spool in different positions. [Figure 23] FIG. 21 is a top view of the valve of FIG. 20. [Figure 24] FIG. 21 is a perspective view of the valve spool of FIG. 20 shown in isolation. [Figure 25] 1 is a line graph illustrating intrathoracic pressure (ITP) and airway pressure over time for a ventilated pair of lungs according to one embodiment of the present disclosure. [Figure 26] FIG. 4 is a schematic diagram illustrating the control logic used to control the valves and pumps of the device of FIG. 3. [Figure 27A] 28 is a flow chart illustrating an algorithm executed by the computing device of FIG. 27 to control the apparatus of FIG. 27. [Figure 27B] 28 is a flow chart illustrating an algorithm executed by the computing device of FIG. 27 to control the apparatus of FIG. 27. DETAILED DESCRIPTION OF THE INVENTION

[0013] Detailed Description Even when excised lungs are ventilated ex vivo by varying the pressure around the lungs to allow them to breathe, it has been recognized that the lungs can benefit from the application of regulated positive pressure within the airways to prevent alveolar collapse during exhalation. For example, applying continuous positive airway pressure (CPAP) in combination with pressure oscillation around the outside of the lungs to facilitate breathing may advantageously regulate the transpulmonary pressure (TPP) gradient in the lung, which may allow for effective recruitment of alveolar segments of the lung parenchyma while reducing, minimizing, or even preventing hyperinflation of the recruited segments.

[0014] It has further been recognized that for practical application of intended ventilation strategies, it is desirable to provide a portable ventilation system that is easy to maintain and operate, yet reliable and has a relatively small footprint. For example, it is desirable to provide a compact and reliable fluid and pressure system for applying and controlling pressure applied to the airways and exterior surfaces of the lungs. In particular, it has been recognized that a reliable and compact valve assembly is desirable for delivering and controlling negative pressure applied to the exterior of the lungs.

[0015] Accordingly, one aspect of the present disclosure relates to an apparatus for ventilating a resected lung, and in particular to a valve assembly for use in a ventilation system. The valve assembly may include a conduit and a valve configured and connected to conveniently control and regulate pressure applied to the exterior of the lung by a single pump, such as a centrifugal or vortex blower, and a relatively simple mechanism for directing and distributing fluid flow within the conduit. Specifically, the valve used in the assembly may be a control valve including three or more input or output ports. A spool is used to control fluid flow between the ports. Specifically, the spool is configured to selectively adjust the proportion of fluid flowing through the different ports. One or more first valves are used to control fluid input to the intake port of the pump. One or more second valves are used to control fluid flow from the output port of the pump. The valves are also connected to the conduits to selectively supply or withdraw fluid from the conduits. The spool may be actuated by a motor. The spool may be a sliding spool and actuated by a linear actuator, or may be a rotating spool actuated by a rotary motor. Advantageously, such an assembly is compact and reliable, as will be described in more detail below.

[0016] Other aspects relate to systems and methods for ex vivo ventilation of the lungs.

[0017] In one exemplary method, ventilation gas is supplied to the airways (e.g., the trachea or bronchi) of the lungs, and pressure is applied to the external surfaces around the lungs. The external pressure may be varied (e.g., cycled) between low and high levels to allow the lungs to breathe, while the pressure of the ventilation gas supplied to the airways may be adjusted to maintain a continuous positive airway pressure within the airways of the lungs. In some applications, the airway pressure may be constant or continuously positive over a period of time during ventilation. Typically, the external pressure may be cycled between two different pressure levels. The levels may be maintained substantially constant over a period of time, or one or both of the low and high levels may be adjusted during ventilation. At least one of the two levels may be less than 1 atmosphere, and a vacuum is created around the lungs when the applied external pressure level is less than 1 atmosphere. The ventilation gas may be filtered with a microbial filter and a humidity-moisture exchanger (HME) filter before being delivered into the lungs. The lungs may be placed in a sealed chamber, and pressure is created around the lungs within the chamber.

[0018] Aspects of the device described herein can be advantageously used for negative pressure ventilation in an ex vivo lung perfusion (EVLP) process or system, or an ex situ lung perfusion (ESLP) system. The application of positive pressure within the lung airways, when combined with such negative pressure ventilation, allows for higher TPP to be achieved without the application of excessive negative pressure outside the lungs.

[0019] The embodiments disclosed herein may also enable recovery of atelectatic alveoli, thereby facilitating long-term EVLP or ESLP. Furthermore, at least some of the embodiments disclosed herein may be conveniently used to measure and obtain functional attributes of ex vivo ventilated lungs.

[0020] An exemplary device 100 for ventilating a resected lung according to one embodiment is illustrated schematically in FIG. 1. As depicted, device 100 includes a container 110 with a sealable chamber 120 for containing lung 130. Within container 110, lung 130 may be supported on a flexible, porous surface, such as a silicone or plastic net, or the lung may be suspended by being placed on a fluid surface covered with a soft plastic membrane (not shown). Alternatively, the lung may be supported on a semi-rigid plastic mold resembling the shape of the posterior thorax to provide a more anatomically conforming position (not shown). Alternatively, the lung may be placed on a pad formed from a material sufficiently resilient to cushion the organ from mechanical vibration and shock during transport. In one embodiment, the pad assembly is formed from silicone, which is biocompatible, impervious to liquids, and can withstand sterilization processes (e.g., ETO). As a note for clarity, the term "a lung" can refer to a single lung, multiple lungs, or portions of a single lung or multiple lungs. Two lungs that are attached to the same trachea are sometimes referred to collectively herein as "the lung" or "the lung."

[0021] The device 100 includes a first fluid system 140 connected to the chamber 120 by a first conduit 150 for applying a variable first pressure to the exterior surface of the lung 130. The pressure within the chamber 120 may be positive or negative at a selected time. As used herein, positive pressure refers to a pressure greater than atmospheric pressure in the immediate environment of the lungs and ventilation device, unless expressly specified otherwise. Negative pressure refers to a pressure less than atmospheric pressure. That is, as used herein, positive pressure refers to a positive gauge pressure, and negative pressure refers to a negative gauge pressure.

[0022] The device 100 may further include a second fluid system 160 for applying and maintaining a second pressure, which may be constant, applied to the airways 170 of the lungs 130. The second fluid system 160 is connected by a second conduit 180 that extends through the wall of the container 110 and connects the second fluid system 160 to the airways 170 of the lungs 130 to supply the second pressure to the airways. The second conduit 180 is sealed so as not to be in pressure communication with the interior space of the chamber 120. The second pressure may be applied using a ventilation gas, such as air or any suitable gas mixture containing oxygen. The second fluid system 160 may include an output port of an air pump or a motor-driven turbine or other air supply mechanism (not shown in FIG. 1 ) to supply air to the lungs at positive pressure. The operating speed of the air pump or turbine may be controlled to regulate the airway pressure within the lungs. Alternatively or additionally, a valve (not shown) in the second fluid system 160 may be used to control or regulate airway pressure.

[0023] A control system 190 may be coupled to the first fluid system 140 and the second fluid system 160. As described in more detail below, the control system 190 may be in communication with a control pressure sensor, a flow sensor, and a flow control valve to vary the pressure in the chamber 120 between low and high vacuum levels to breathe into the lungs 130, and to regulate the pressure of the ventilation gas delivered by the second fluid system 160 to maintain a continuous positive airway pressure in the airways 170 of the lungs 130.

[0024] Referring to FIG. 2A, a valve assembly 200 suitable for use within fluid system 140 is shown. Valve assembly 200 is configured to supply or remove fluid from chamber 120 via conduit 150 with pump 208, thereby applying variable pressure to the exterior surface of lung 130. The fluid may be air or a suitable gas supplied from a gas source (not shown). In one embodiment, the fluid is air from the atmosphere. Valve assembly 200 includes conduit 202 for connecting with conduit 150 to remove fluid from conduit 150, and conduit 203 for supplying fluid to conduit 150. Valve assembly 200 also includes two three-way control valves 204, 206 with ports 216, 222 for connecting with conduit 150 and ports 214 and 220 for connecting with intake port 210 and output port 212, respectively, of pump 208. Valve 204 also has an air intake port 218 and valve 206 has an exhaust port 224 .

[0025] Specifically, port 214 of valve 204 is an output port and is connected by conduit 211 to intake port 210 of pump 208. Port 216 of valve 204 is an input port and is connected to conduit 202 for removing fluid from chamber 120 through conduit 150. Port 220 of valve 206 is an input port and is connected by conduit 213 to output port 212 of pump 208. Port 222 is an output port and is connected to conduit 203 for supplying fluid to chamber 120 through conduit 150.

[0026] Each of the valves 204, 206 may have a construction as shown in FIG. 2B, which illustrates a three-way control valve 700. The valve 700 has a port 702 positioned on a first side of the valve 700 and in fluid communication with two ports 704 and 706 positioned on a second side of the valve 700, the second side being opposite the first side as depicted in FIG. 2A. As described in more detail below, a control unit 205 is provided within the valve 700 to allocate fluid flow between the two ports 704 and 706. Fluid flow through the valve 700 may be in the direction from port 702 to ports 704 and 706, or in the opposite direction.

[0027] 2A, control 205 controls the proportion of fluid entering valve 204 through ports 216 or 218. Fluid removed from chamber 120 via conduits 150, 202 can enter valve 204 through port 216. New fluid, such as air or oxygen-enriched air, can enter valve 204 through intake port 218 and thus be added to the fluid flow.

[0028] 2A, control unit 205 controls the rate at which fluid exits through ports 222 and 224. By allowing fluid to exit through port 222, fluid is added to chamber 120 via conduits 203, 150. By allowing fluid to exit through exhaust port 224, fluid can be removed from the fluid flow. In the manner described above, fluid can be supplied to or removed from chamber 120 by pump 208 without the need to vary the pump speed or use multiple pumps.

[0029] When pump 208 and conduit 150 are connected to valve assembly 200 as described above and shown in Figure 2A, pump 208 may be used to control and regulate the pressure within chamber 120, as described in more detail below. Valve assembly 200 and pump 208 thus form part of fluid system 140. Fluid system 140 may include other components, such as sensors, filters, processors, and additional pumps.

[0030] Possible constructions and exemplary embodiments of the valve 700 are described below with reference to FIGS.

[0031] 3 illustrates an exemplary embodiment of the apparatus 100 shown in FIG. 1 , apparatus 300 illustrating the use of valve assembly 200. Apparatus 300 includes a fluid system 400 that includes valve assembly 200, an exemplary embodiment of first fluid system 140 described above and shown in FIG. 2A . Fluid system 400 further includes a three-way connection 426 for connecting conduit 150 with ports 216 and 222 via conduits 202, 203 to either remove fluid from or add fluid to conduit 150. Three-way connection 426 may include a three-way valve or a T-junction, Y-junction, or the like.

[0032] Fluid system 400 also includes a fluid filter 428 mounted or connected to port 218 of valve 204 via conduit 429, and a fluid filter 430 mounted or connected to port 224 of valve 206 via conduit 431. Filters 428, 430 may be high efficiency particulate air (HEPA) filters to filter out particles from the incoming air. Filter 432 may also be positioned within conduit 150, and may be a humidity and moisture exchanger (HME) to maintain humidity within chamber 120 and prevent drying of lungs 130.

[0033] Fluid system 400 may further include an integrated sensor 434 coupled to conduit 150. Sensor 434 may be configured to detect pressure, flow, humidity, gas content, etc. within conduit 150. Sensor 434 may be an FS6122-250F250-100P100-TH1 sensor made by Siargo™.

[0034] Device 300 further includes a second fluid system 500, which is one exemplary embodiment of fluid system 160 described above. Fluid system 500 is configured to apply and maintain airway pressure within airway 170 of lung 130. Fluid system 500 is coupled to airway 170 via conduit 180 and includes pump 506, connected as shown. Specifically, pump 506 has an intake port 508 and an output port 510. Intake port 508 receives a fluid supply from conduit 531, which may include a three-way connection 521, which may be a three-way valve or a T-junction or Y-junction. Fluid may be drawn from the atmosphere through conduit 519 and into conduit 531 via three-way connection 521. Conduit 519 may also include a valve 515 for controlling fluid flow from the atmosphere. Alternatively, oxygen may be supplied to conduit 531 from an oxygen supply 529 via conduit 527. Conduit 527 may also include valve 525 for controlling oxygen flow from oxygen supply 529. Valves 515 and 525 may be two-way proportional solenoid valves and may optionally be controlled by control system 600. Through control of valve 525, the supply of air or an air and oxygen mixture to conduit 531 may be regulated.

[0035] Fluid system 500 may further include fluid filters 518, 520. Fluid filter 518 may be mounted or connected to conduit 519 to filter the air entering pump 506. Fluid filter 520 may be positioned between conduits 511 and 180 and may be an HME filter to retain humidity in the trachea and prevent humidity from entering the valve. This is important to prevent tissue desiccation in lung 130 and to avoid bacterial contamination within fluid system 500. Filter 518 may be a HEPA filter to filter out particles from the incoming air.

[0036] Any suitable microbial filter, such as a HEPA filter or HME filter known to those skilled in the art, may be used as a filter in one embodiment herein. Products with both HME and HEPA characteristics exist on the market. In this embodiment, filters 428, 430, 432, 518, and 520 are combined HEPA / HME filters.

[0037] Fluid system 500 may further include an integrated sensor 522 coupled to conduit 511. Sensor 522 may be configured to detect pressure, flow, or humidity within second fluid system 500. An oxygen sensor 523 may also be coupled to output port 510 of pump 506 to detect oxygen content within second fluid system 500.

[0038] Apparatus 300 further includes control system 600, which is one exemplary embodiment of control system 190. Control system 600 is in communication with valves 204, 206, pump 208, and sensor 434 of system 400, and pump 506 and sensors 522, 523 of fluidic system 500. In some embodiments, fluidic system 400 and fluidic system 500 may include separate or additional control systems. Control system 600 is configured to control the operation of pumps and valves to regulate the direction and pressure of fluid flow within apparatus 300.

[0039] Providing separate pumps for the separate fluid systems 400, 500 in device 300 allows each system 400 or 500 to be more compact, while providing more powerful and simpler control of each system. This configuration also reduces the risks associated with component failure within the device, since if one of the fluid systems 400, 500 fails, the other system may still function properly. Providing separate fluid systems 400 and 500 with their own dedicated pumps further allows for the use of smaller, quieter, and more compact pumps within each system.

[0040] As will be described below, in operation, device 300 may be operated to ventilate lungs ex vivo as illustrated in Figures 4 and 5. In Figures 4 and 5, lines with arrows indicate the direction of airflow.

[0041] 4 illustrates fluid flow within device 300 during inspiration. Valves 204 and 206 are configured, under the control of controller 600, to allow fluid flow between ports 216 and 214 in valve 204 and between ports 220 and 224 in valve 206, but to block fluid flow between ports 222 and 220 in valve 206, so that air can flow from container 110 through filter 432, conduits 150, 202, and junction 426 into valve 204 via port 216, but not through port 222 into valve 205. For inspiration, pump 208 is actuated to pump air from intake port 210 toward output port 212 at a selected pumping speed or rate. As a result, air is drawn from chamber 120 of container 110, and air received at port 216 of valve 204 is directed to flow through port 214 into intake port 210 of pump 208. Air pumped into valve 206 through output port 212 is directed by valve 206 to port 224 and then vented to atmosphere through filter 430. In this manner, the pressure inside chamber 120 of container 110 is reduced, applying negative pressure to the exterior of lung 130. The pressure in conduit 150 may closely reflect the pressure in chamber 120 and may be measured using sensor 434. Controller 600 may be configured to monitor the pressure within container 110 (which may be measured by sensor 434) over a specified time frame until adjusting valve 204 to stop the removal of fluid from container 110 through port 216. In some embodiments, the rate of airflow through conduit 150 may be controlled by the pumping speed of pump 208. In some embodiments, the rate of airflow through conduit 150 may be controlled by adjusting valve 204 while the pump speed is held constant. For example, valve 204 may be adjusted to allow some outside air to enter the airflow stream to port 214 through port 218, thus reducing the amount of air drawn through conduits 202 and 150.

[0042] Alternatively or additionally, valve 206 may be controlled to allow a selected percentage of the air flowing through port 220 to flow through port 222, conduit 203, and junction 426 back to conduit 202, which also reduces the flow rate of air through conduit 150 from vessel 110 to junction 426. In some embodiments, the fluid flow rate in conduit 150 may be controlled by adjusting two or more of valves 204, 206, and pump 208.

[0043] For example, in some applications, the valve 204 may be controlled by state control, i.e., by controlling the movement of the valve from a 0% (fully closed) position or state to a 100% (fully open) position or state, to control the breathing state, and the pressure in the chamber 120 and the inspiratory rise time (T i A valve 206 may be used to regulate the

[0044] During the same inhalation phase, subsystem 500 provides air or oxygen-containing gas into lungs 130 through airway 170. For example, pump 506 may be activated to pump air from intake port 508 to output port 510 at a selected rate. As a result, external (e.g., ambient) air is drawn into intake port 508 of pump 506 through conduits 519, 531, and filter 518 and supplied to airway 170 through output port 510, conduit 511, filter 520, and conduit 180. In this manner, positive pressure is applied to airway 170 of lungs 130. In one mode of operation, valve 525 may be closed. In a different mode of operation, valve 525 may be opened so that oxygen gas in oxygen source 529 is pumped through conduit 527 and mixed with the air in conduits 521 and 531 at connection 521. As a result, the air supplied to airway 170 is enriched with oxygen. The percentage of oxygen added to the airflow may be regulated by adjusting valve 525 under the control of controller 600. The oxygen content or level in the air in conduit 511 may be measured using oxygen sensor 523, and valve 525 may be controlled by controller 600 based on the measured oxygen level.

[0045] The pressure difference between the positive pressure applied to the airways 170 and the negative pressure applied outside the lungs 130 causes the lungs to expand, thus inhaling air.

[0046] The combination of applied negative and positive pressure, as described above, also creates a pressure gradient from the airways 170 to the alveoli, which causes some air to flow into and through the alveoli. Some air may pass through the lungs 130 and into the chamber 120.

[0047] 5 illustrates airflow within device 300 during exhalation under several circumstances. Valves 204 and 206 are configured under the control of controller 600 to allow fluid flow between ports 218 and 214 in valve 204 and between ports 220 and 222 in valve 206, but to block fluid flow between ports 214 and 216 in valve 204, so that air can flow from valve 206 through port 222, conduits 203 and 150, junction 426, and filter 432 to container 110, but not from port 216 to port 214. Also for exhalation, pump 208 is operated to pump air from intake port 210 toward output port 212 at a selected pumping rate. As a result, outside air is drawn into valve 204 through port 218 and filter 428, and then into pump 208 through conduit 211 and intake port 210. The air is pumped through output port 212 and conduit 213 to valve 206, directed by valve 206 to port 222, and supplied back to reservoir 110 through conduits 222, 150, junction 426, and filter 432. In this manner, the pressure inside chamber 120 of reservoir 110 is increased, increasing the pressure applied to the exterior of lungs 130. It is noted that during exhalation, pressure within the airways may become negative, in which case device 300 may operate in a manner similar to the inhalation phase described above.

[0048] During the exhalation phase, the subsystem 500 may continue to supply air or oxygen-enriched air to the airways 170 of the lungs 130 to maintain positive pressure within the airways 170 of the lungs 130 in a manner similar to that described above during the inhalation phase.

[0049] In either case, during exhalation, the increased pressure outside the lungs 130 reduces the pressure differential between the airways 170 and the chamber 120, thus causing the lungs to exhale and allow air to flow from the alveoli into the airways 170 and out of the lungs 130.

[0050] Valves 204 and 206 can be controlled by controller 600 through adjustments to control portion 205 to alternately either add fluid to or remove fluid from conduit 150, thus causing the pressure inside chamber 120 to oscillate between low and high pressure levels.

[0051] Control system 600 may function in a number of different ways to control the inhalation and exhalation cycles of device 300. In a first embodiment, pump 208 may operate constantly at a fixed speed throughout the inhalation and exhalation cycles, and control system 600, through adjustment of controller 205, adjusts valves 204 and 206 to operate proportionally to appropriately apportion airflow. That is, airflow may be directed from either port 216 or 218 of valve 204 to port 214, or the proportion of fluid entering valve 204 through ports 216 and 218 may be controlled. In a similar manner, airflow may be directed from port 220 of valve 206 to either port 222 or 224, or apportioned between ports 222 and 224.

[0052] In another embodiment, control system 600 adjusts and regulates the speed of pump 208 while modulating valves 204 and 206, which function as non-proportional three-way valves, between a number of setpoint positions. As described in more detail below, control system 600 may operate to adjust and regulate the speed at which the valves move between setpoint positions to control the timing between stages of a breathing profile. That is, airflow may be directed from either of ports 216 and 218 of valve 204 to port 214, but is not apportioned from ports 216 and 218 to port 214. In a similar manner, airflow may be directed from port 220 to either of ports 222 and 224 of valve 206, but is not apportioned between ports 222 and 224.

[0053] As can be appreciated, the speed at which valves move between different set positions or open / closed states can have a significant impact on breath timing control. Accordingly, in embodiments disclosed herein, system 300 may be configured to vary the speed at which each valve moves between different valve positions according to a timing setpoint, which may be set by an operator or user. Such speed control may be advantageously achieved by the example valve assemblies described herein.

[0054] In another embodiment, control system 600 may regulate and adjust the speed of pump 208, while also proportionally adjusting valves 204 and 206 through adjustment of controller 205 to properly allocate airflow. That is, airflow may be directed from either port 216 or 218 of valve 204 to port 214, or the proportion of fluid entering valve 204 through ports 216 and 218 may be controlled. In a similar manner, airflow may be directed from port 220 of valve 206 to either port 222 or 224, or may be apportioned between ports 222 and 224.

[0055] Control system 600 may also function to maintain a constant positive airway pressure (CPAP) in airway 170 through adjusting and regulating the speed of pump 506 while adjusting valves 515 and 525 between several fixed positions. In one embodiment, pump 506 may operate constantly at a fixed speed, and control system 600 adjusts valves 515 and 525 so that fluid flows from the atmosphere through conduits 519, 531, 511, 180 and into airway 170. In another embodiment, control system 600 adjusts valves 515 and 525 so that oxygen from an oxygen source mixes with air from conduits 519 and 531 at connection 521. The oxygen content or level in the air in conduit 511 may be measured using oxygen sensor 523, and valve 525 may be controlled by controller 600 based on the measured oxygen level. In some embodiments, valve 515 may be omitted when the pressure in conduit 180 is controlled using a pump, such as pump 506.

[0056] The controller 600 may control the pumps and valves within the device 300 to provide a desired or selected breathing profile.

[0057] An exemplary respiratory profile is shown in Figure 25. In this example, ITP i The set point for ITP is -11 cmH2O. e The set point for ITP was 1 cmH2O. i and ITP e corresponds to the minimum and maximum pressures in the container 110 measured by the sensor 434 during inspiration and expiration, respectively.

[0058] Expiratory rise time (T e ) is the time when ITP begins to rise following inspiration and then e The inspiratory rise time (T i ) is the time when ITP begins to fall after expiration and then iis the time it takes to reach

[0059] Expiratory time (ET) is the calculated time span that the lungs are in an exhalation state, while inhalation time (IT) is the calculated time span that the lungs are in an inhalation state. ET can be calculated from ((1 / RR) × (E / I+E)). RR is the respiratory rate, or cycles per minute in breaths per minute (BPM). Similarly, IT can be calculated from ((1 / RR) × (I / I+E)). I and E are simplified integers used in the I:E ratio, which is the reduced form of ET and IT in the ratio. For example, if IT = 4 seconds and ET = 2 seconds, then I:E = 4:2 = 2:1.

[0060] Cycle time (T cycle ) is the sum of ET and IT. The inspiration to expiration time ratio ("I:E") is the ratio of IT to ET.

[0061] Figure 25 shows the T i Two profiles about T i (a) and T i (b) is shown. T i (a) corresponds to a short inspiratory rise time, and T i (b) corresponds to the full inspiratory rise time, which is measured by sensor 434. A short inspiratory time may be used, for example, when the lung is non-compliant or requires recruitment. A non-compliant lung refers to a lung that is poorly expandable (or has poor lung compliance). Lung recruitment refers to a temporary increase in airway pressure to open collapsed alveoli. In such a scenario, a short inspiratory rise time, followed by ITP, may be used. i A longer pause at 1000 rpm may be beneficial, which may improve lung compliance and recruitment.

[0062] In some embodiments, ITP emay range from -10 cmH2O to 10 cmH2O, and ITP i A minimum of -30 cmH2O may be used.

[0063] 25 also illustrates the applied constant positive airway pressure (CPAP) as measured by sensor 523. In some embodiments, the CPAP may be maintained at 7.5 cmH2O. Based on the pressure measured in conduit 511 by sensor 523, the desired pressure may be maintained through adjustment of the speed of pump 506 by controller 600.

[0064] FIG. 26 illustrates the control logic for controlling valves 204 and 206 and pump 208. Control may be implemented using a proportional-integral-derivative (PID) controller or any standard variant of PID control. As will be appreciated by those skilled in the art, a PID controller continually calculates an error value as the difference between a desired set point (SP) and a process variable (PV) to derive a control output (CO). The PID controller attempts to reach the desired set point over time by continually reducing the error value by adjusting the control output. A control system may include one or more PID controllers to control one or more variables. Multiple PID controllers may attempt to reach multiple desired set points. Set points may be pre-saved or manually entered by a user in one embodiment, and are stored in the ITP. i (I-PD control), ITP e (I-PD control), RR, I:E, T e (IP control), and T i (IP control).

[0065] 26, which control system 600 may follow, may be used to control proportional fluid flow through valves 204 and 206 by adjusting the speed of controller 205 and pump 208. In this logic, the pressure ITP measured by sensor 434 in conduit 150 during inspiration i , or ITP (measured by sensor 434) during exhalation e is the desired ITP i and ITP e The difference between the actual value measured by sensor 434 and the set point is used as feedback to adjust only the valves 204 and 206, only the speed of the pump 208, or both the valves 204 and 206 and the speed of the pump 208.

[0066] During operation of the fluid system 400, the configuration of the valves 204 and 206 is controlled by the user via the ITP. e It may depend on the value of the input. e For < 0, valves 204 and 206 may maintain the same configuration throughout both the inhalation and exhalation states. This configuration is achieved by adjusting controller 205 to configure valve 204 to flow air into pump 208 through port 214, and by adjusting controller 205 to configure valve 206 to vent air to the atmosphere through port 224. During each of the inhalation and exhalation states, the user-entered target ITP i and ITP e during inspiration and expiration, respectively, i (during inspiration) or ITP e Based on this (during exhalation), the speed of the pump 208 may be adjusted by the control system 600 .

[0067] ITP e≧1, the configuration of valves 204 and 206 achieved through adjustment of controller 205 depends on whether the system is operating in an inhalation state or an exhalation state. During the inhalation state, valve 204 is configured to allow air to flow from port 216 through port 214 into pump 208, and valve 206 is configured to expel air to the atmosphere via port 224. During the exhalation state, valve 204 is configured to allow air to enter pump 208 through port 218, and valve 206 is configured to allow air to flow from port 222 into conduit 150. During each of the inhalation and exhalation states, the user-entered target ITP i and ITP e during inspiration and expiration, respectively, i (during inspiration) or ITP e (during exhalation), the speed of the pump 208 may be adjusted by the control system 600. The manner in which the speed of the pump 208 is adjusted by the control system 600 depends on the T i and T e It depends on the value of T i < 2 seconds or T e < 2 seconds, respectively, set point ITP i or ITP e The speed of the pump 208 may be momentarily pulsed or ramped at the beginning of an inhalation or exhalation state, respectively, to accelerate the pressure within the reservoir 110 towards reaching .

[0068] The pulse / ramp waveform of the pump 208 is T i or T e may be controlled by a PID controller as described above with a user input value of T as the setpoint, where the PID controller i or T eBased on the measured error (process variable), an attempt can be made to reach the desired set point over time by continually reducing the error value through adjustment of the pump speed multiplier (control output) of pump 208 while maintaining a constant pulse duration, which may be 0.5 seconds. The pump speed multiplier may range from 0 to 4. If the pump speed multiplier is < 1, a ramp-up effect occurs. Ramping from the pulse to a steady rate may occur over 50% of the total breath length of either inspiration or expiration.

[0069] ITP e < 0 cmH2O, the speed of the pump 208 is always increased during inspiration and decreased during expiration. i > 2 seconds or T e > 2 seconds, and ITP e For ≦0 cmH2O, the speed of the pump 208 is changed at a rate calculated to achieve the pressure in the reservoir 110. i > 2 seconds, the pump 208 speed is adjusted to match the user-input ITP during inspiration. i It grows at a rate calculated to achieve T e > 2 seconds, the pump 208 speed is adjusted to match the user-input ITP during exhalation. e The signal is reduced at a rate calculated to achieve

[0070] The speed of the pump 208 is calculated using equation (1): TIFF2025531573000002.tif9128, where b is the speed of the pump 208 as a percentage of the full range (b s and b f are the starting and final speeds of the pump 208, respectively; t is the time from the start of switching between exhalation and inspiration (or vice versa); a and C are constants, and C is preferably 0.9.

[0071] The constant a is given by equation (2): may be computed from TIFF2025531573000003.tif7128, where A = 1.5 if bs > bf, and A = 1 otherwise.

[0072] T i > 2 seconds or T e > 2 seconds and ITP e > 0 cmH2O, the speed of pump 208 is adjusted in the same manner as described above. In addition, valves 204 and 206 are configured by control system 600 through adjusting control section 205 at a second calculated rate to achieve pressure within vessel 110. T i > 2 seconds, then user-entered ITP during inspiration i The valves 204 and 206 are adjusted at a second calculated rate to achieve T e > 2, then user-entered ITP during exhalation e Valves 204 and 206 are adjusted at a second calculated rate to achieve

[0073] The rate of adjustment of the control section 205 of the valves 204 and 206 is given by equations (3) and (4): Determined by TIFF2025531573000004.tif24128.

[0074] In equations (3) and (4), x0, x 0.5 , and x1 represent the start point, the middle point, and the end point in the control unit 205, respectively, and t 0.5 , and t1 represent the start time, the time at the midpoint, and the time at the end point during adjustment by the control unit 205, respectively.

[0075] The parameters listed in Table 1 below are used to modify the values ​​in equations (3) and (4) to adapt the behavior of the physical system at different set points. Note that during inspiration, the subscripts s and f (referring to start and end) refer to expiration and inspiration, respectively, and are swapped for expiration. In terms of names, b refers to the speed of the pump 208, and ITP refers to the set point for ITP (ITP e or ITP i ), v refers to the valve position data defined for valves 204 and 206, and x refers to the valve position determined in the context of the controller.

[0076] [Table 1]

[0077] In Table 1, valve position v s and v f is known. T i / e and ITP s / f The values ​​of are the desired set points, which are also known. The baseline valve chute V is a defined constant (0-1) that defines the baseline to which the valve will immediately move when switching between respiratory states.

[0078] P characterizes the difference in lamp blower speed between the opening and closing states of the breath, and is the contextually corrected valve chute x shoot is used to correct the baseline valve chute (V) to determine the velocity of the pump 208. This is necessary because the valve chute is dependent on the speed transition of the pump 208, and the valve shooting may become too steep during ramp down.

[0079] M is the transition time and position, t, to accommodate the dynamic nature of the pressure equilibration of the system. 0.5 and x 0.5 is a bounded modifier that fine-tunes M. It was found that a constraint on M near the midpoint valve position is necessary to prevent M from overcompensating for the midpoint parameters.

[0080] Figure 27A shows the ITP e 4 is a flowchart of an algorithm S3100 that may be executed by one or more controllers, processors, or computers to control an apparatus, such as apparatus 300 in FIG. 3, when ITP ≦0. In this example, the set point entered by the user is i = -10 cmH2O, ITP e = -2 cmH2O, T i = 1 second, T e = 3 seconds, RR = 10 BPM, and I:E = 1:1.

[0081] The software is initiated by a signal provided by a user or an automated process at block S3102. At block S3104, valve 204 is configured by adjusting control 205 to allow air to flow through port 214 into pump 208, and valve 206 is configured to vent air to the atmosphere through port 224.

[0082] The inspiratory state of the device begins in block S3106, and in block S3108, the pump 208 is signaled to pulse and ramp up to a certain rate to increase airflow into the conduit 150. In block S3110, the pressure sensor 434 is sampled, and in block S3112, the algorithm calculates the pressure at the set T i Within ITP i Determine whether ITP has been reached (especially as may occur during the first ventilation cycle). i If ITP has not been reached, an adjustment to the speed of the pump 208 is made at block S3114 for the next ventilation cycle before proceeding to block S3116. i If so, no adjustment is necessary and the algorithm proceeds directly to block S3116. As discussed above with respect to Figure 26, blocks S3112 and S3114 may include PID calculations.

[0083] At block S3116, the exhalation state begins. Following the exhalation state beginning, at block S3118, the set T e Configured within ITP e A signal is sent to reduce the speed of the pump 208 to reduce the airflow into the conduit 150 to reach T. At block S3120, the pressure sensor 434 is sampled, and at block S3122, the algorithm calculates the airflow rate at the set T. e Within ITP e Determine whether ITP has been reached (especially as may occur during the first ventilation cycle). e If ITP has not been reached, an adjustment to the speed of the pump 208 is made at block S3124 for the next ventilation cycle before proceeding to block S3116. e If so, no adjustment is necessary and the algorithm proceeds directly to block S3126. As discussed above with respect to Figure 26, blocks S3122 and S3124 may include PID calculations.

[0084] At block S3126, the algorithm checks for user input (e.g., a change in set point). At block S3128, it is determined whether the operating settings should be reconfigured. Reconfiguration may be required if a different operating mode is desired. If the settings are not reconfigured, the software returns to block S3106 to repeat the inspiration state. If the settings are reconfigured, for example, to start a new operating mode, ventilation is stopped at block S3130.

[0085] Figure 27B shows ITP e 10 is a flowchart of another algorithm S3200 that may be executed by one or more processors S3202 to control an apparatus of the present disclosure, such as apparatus 300 in FIG. 3, when ITP ≥ 1. In this example, the set point entered by the user is i = -10 cmH2O, ITP e = 5 cmH2O, T i = 1 second, T e= 3 seconds, RR = 10 BPM, and I:E = 1:1.

[0086] The software is initiated by a signal provided by a user or an automated process at block S3202. The inhalation state of the device begins at block S3204, and at block S3204, valve 204 is configured by adjusting control 205 to allow air to flow from port 216 through port 214 into pump 208, and valve 206 is configured to vent air to the atmosphere via port 224.

[0087] At block S3208, the pump 208 is signaled to pulse and ramp up to a certain rate to increase the airflow into the conduit 150. At block S3210, the pressure sensor 434 is sampled, and at block S3212, the algorithm calculates the pressure at the set T i Within ITP i Determine whether ITP has been reached (especially as may occur during the first ventilation cycle). i If ITP has not been reached, an adjustment to the speed of the pump 208 is made at block S3214 for the next ventilation cycle before proceeding to block S3216. i If so, no adjustment is necessary and the algorithm proceeds directly to block S3216. As discussed above with respect to Figure 26, blocks S3212 and S3214 may include PID calculations.

[0088] At block S3216, an exhalation state begins. Following the initiation of the exhalation state, at block S3220, valve 204 is configured by adjusting control 205 to admit air into pump 208 through port 218, and valve 206 is configured by adjusting control 205 to direct air through port 222 and into conduit 150. The rate at which control 205 is adjusted depends on the set point entered by the user. ITP e If < 0 cmH2O, no adjustment is made to the control unit 205 and the ITP e > 0 cmH2O and Ti / T e If < 2, the control unit 205 switches as fast as possible as described above. e > 0 cmH2O and T i / T e If > 2, the control unit 205 runs at the calculated rate (as described above).

[0089] At block S3220, the desired T e ITP e A signal is sent to reduce the speed of the pump 208 to reduce the airflow into the conduit 150 to reach the set point. The pressure sensor 434 is sampled in block S3222, and the software calculates T e ITP at set point e Determine whether ITP is reached (especially as may occur during the first ventilation cycle). e If ITP has not been reached, an adjustment to the speed of the pump 208 is made in block S3226 for the next ventilation cycle before proceeding to block S3228. e If so, no adjustment is necessary and the algorithm proceeds directly to block S3228. As discussed above with respect to Figure 26, blocks S3224 and S3226 may include PID calculations.

[0090] At block S3228, the software checks for user input (e.g., a change in set point). At block S3230, it is determined whether the operating settings should be reconfigured, such as by loading a new configuration file. Reconfiguration may be required if a different operating mode is desired. If the settings are not reconfigured, the software returns to block S3204 to repeat the inspiration state. If the settings are reconfigured, such as to start a new operating mode, ventilation is stopped at block S3232.

[0091] In some embodiments, any necessary adjustments to the device at block S3226 may instead be made immediately prior to block S3204.

[0092] The second fluid system is also controlled by control system 200, but may operate autonomously from the first fluid system to provide constant positive airway pressure (CPAP) to lungs 130. Pump 506 is operated at a particular speed to achieve and / or maintain a user-defined CPAP set point corresponding to the desired pressure in airway 170. Regulation of pump 506 is based on feedback from sensor 522, which may be configured to detect pressure in conduit 511. In the example shown in the respiratory waveform shown in FIG. 25, the pressure within airway 170 as measured by sensor 552 may be 7.5 cmH2O.

[0093] 6A is a schematic diagram illustrating additional components of a valve 700 suitable for use in any of the fluid systems 140, 160, 200, or 400 described above, as a specific embodiment of valves 204 and 206. As described above, valve 700 has ports 702 grouped on one side of the valve and in communication with a second group of ports 704 and 706 on the opposite side via a conduit 709. To perform the function of control unit 205, valve 700 has a spool 708 movable within conduit 709 to direct fluid flow between the two groups of ports. By doing so, valve 700 can selectively adjust the proportion of fluid flowing through ports 704 and 706 to regulate flow rate and pressure without changing pump speed within any of the fluid systems described above. Spool 708 is movable between at least two positions by an actuator 710. Actuator 710 includes a motor 712, a drive shaft 714, a connector 716, and a proximity sensor 718. Drive shaft 714 is coupled to spool 708 by connector 716 and functions to position spool 708. Proximity sensor 718 determines the home position of drive shaft 714 and provides an output signal to controller 720, which controls the position of drive shaft 714 via motor 712.

[0094] 6B-D illustrate three general embodiments of a valve 700 to illustrate the use of a movable spool to control fluid flow between two groups of ports.

[0095] Referring to FIG. 6B , valve 1600 includes three ports in communication with cylindrical bore 1608: port 1602 grouped on one side, and ports 1604 and 1606 grouped together on the opposite side. A spool 1610 is housed within bore 1608 to selectively control flow between the two groups of ports. The spool is linearly movable within bore 1608 and can block or allow flow between the two groups of ports. In the position shown in FIG. 6B , flow through port 1604 is blocked, while flow to / from port 1602 and to / from port 1606 is allowed through openings 1612 and 1614 in the spool (as indicated by the directional arrows). As described in more detail below, the position of spool 1610 may be adjusted to precisely control the relative fluid flow to and from each of second and third ports 838 and 840.

[0096] Referring to Figure 6C, valve 1700 is depicted, which is similar in design and function to valve 1600. In this embodiment, ports 1704 and 1706 are grouped together in a roughly V-shaped arrangement. One advantage of this configuration is that there is a lower pressure drop across the valve, with the flow paths exiting at 45 degrees rather than 90 degrees. This increases the efficiency of the valve when installed in a fluid system such as 300.

[0097] Referring to Figure 6D, valve 1800 has three ports in communication with cylindrical bore 1808: port 1802 grouped on one side, and ports 1804 and 1806 grouped together on the opposite side. In this embodiment, spool 1810 is housed within bore 1808 and is configured to move rotationally to block or allow flow between the two groups of ports. In the position shown in Figure 6D, flow through port 1804 is blocked, while flow to / from port 1802 and to / from port 1806 is allowed through openings 1812 and 1814 in the spool (as indicated by the directional arrows).

[0098] Of course, other positions of spools 1610 and 1810 are possible to open and close different paths for fluid flow, as will be described in more detail below.

[0099] A first embodiment of a valve 800 suitable for use in any fluid system is shown in Figures 7A-B, 8A-B, 9A-C, and 10A-F.

[0100] 7A-B and 8A-B, valve 800 has a generally rectangular valve base 802 to which a housing 804 is attached using a suitable method, such as screws, at its top surface 802a. Housing 804 is rectangular in shape and includes a recessed spool opening 808 located at an end surface 804b of housing 804. Housing 804 may be made of a suitable material, such as aluminum. A lid plate 810 is sized to fit within spool opening 808 and is securely fastened in place using a suitable method, such as screws 812. An O-ring 809 located in a groove 811 in spool opening 808 provides a seal between spool opening 808 and lid plate 810. O-ring 809 may be made of rubber or any other suitable material.

[0101] A motor mount 814 is positioned on the top surface 804a of the housing 804. The motor mount 814 is generally flat and rectangular and provides a surface for mounting a motor 816. In this embodiment, the motor 816 may be a linear DC servomotor, such as the LM1247-020-01 linear DC brushless micromotor manufactured by MicroMo Electronics™. The motor 816 includes a drive shaft 820. The motor mount 814 also has a flange-like tab 822 protruding perpendicular to the top surface 804a, to which a proximity sensor 824 may be attached. The proximity sensor may be any suitable sensor, such as the GX-F8A-P inductive proximity sensor manufactured by Panasonic. As described in more detail below, the proximity switch is configured to detect the position of the drive shaft 820, particularly a home position for the drive shaft. The valve base 802, housing 804, lid plate 810, and motor mount 814 may be made of any suitably strong material, such as aluminum.

[0102] An electronics mount 826 is also secured to the top surface 802a of the valve base 802. The electronics mount 826 includes two feet 828 that contact the surface 802a of the valve base 802 and are secured by a suitable method, such as screws (not shown). The electronics mount 826 further includes two legs 830 that extend vertically upward from the feet 828 to a vertical, rectangular backing plate 832. A controller 834 is secured to the backing plate 832. In this embodiment, the controller 834 may be an MCLM3002SRS motor controller manufactured by MicroMo Electronics™. The electronics mount 826 may be made from any suitably strong material, such as acetyl plastic.

[0103] 8A-B and 9A-C, housing 804 further includes first port 836, second port 838, and third port 840. First port 836 is located on face 804c of housing 804, and second and third ports are located on opposite face 804d of housing 804. Ports 836, 838, and 840 are cylindrical passages that extend inwardly toward the center of housing 804 to communicate with central cylindrical bore 842. Cylindrical bore 842 extends along the longitudinal axis of housing 804 and terminates at one end in spool opening 808. At the opposite end of cylindrical bore 842 is rod connector opening 844 that exits through face 804e of housing 804 (FIG. 8B). Cylindrical bore 842 may not be perfectly circular in cross section and may include a flat portion 843 located on its bottom surface.

[0104] To provide a fluid connection between first port 836 and any tubing or conduit used to either receive fluid from or supply fluid to valve 800, a first port connector 846 is provided, comprising a flanged portion 848 and a tubular portion 852 (FIG. 8B). Flanged portion 848 of first port connector 846 contacts surface 804c of housing 804, where first port 836 exits housing 804. To provide a seal, an O-ring 850 may be provided that sits in groove 851 and conforms to the outer periphery of port 836 at surface 804c to seal between housing 804 and first port connector 846 when secured by screws 854. Tubular portion 852 of first port connector 846 is sized to receive tubing, such as tubing 856, of a tubing fixture or conduit, as shown in FIG. 8B. Tubing 856 may be secured by any suitable means, such as a tubing clamp (not shown).

[0105] Similar to the above, a second port connector 858 and a third port connector 860 are also provided to provide fluid connections between the second and third ports 838, 840, respectively, and any tubing or conduits used to either receive fluid from or supply fluid to the valve 800. The second port connector 858 is mounted to the face 804d of the housing 804 using threads 862 and is sealed with an O-ring 864 located in a circular groove 866 in the face 804d. Similarly, the third port connector 860 is mounted to the face 804d of the housing 804 using threads 868 and is sealed with an O-ring 870 located in a groove 872 in the face 804d that follows the outer periphery of the port 860. The first, second, and third port connectors 846, 858, 860 may be made from any suitably strong material, such as aluminum. The O-rings 850, 864, 870 may be rubber or any other suitable material.

[0106] A spool 874 is provided mounted within the cylindrical bore 842 to selectively adjust the proportion of fluid flow through the second and third ports 838, 840. The spool 874 is hollow and generally cylindrical in shape with three openings on its cylindrical surface and is sized to fit snugly within the cylindrical bore 842. The outer surface of the spool 874 may include a flattened region 875 that aligns with the flat portion 843 of the cylindrical bore 842, ensuring proper alignment of the spool within the cylindrical bore during assembly ( FIG. 8A ). A first opening 876, which is generally rectangular in shape, is located on the curved surface of the spool 874. A second, smaller, generally rectangular opening 878 is located on the curved surface opposite the first opening 876. A third opening 880 is located at the end of the spool 874 closest to the lid plate 810. The spool 874 may be made from any suitably strong material, such as acetal plastic.

[0107] Spool 874 may be sized to have a clearance of approximately 0.15 mm between its outer surface and the cylindrical bore. Spool 874 may be manufactured from a suitable material with a low coefficient of friction, such as acetyl plastic.

[0108] The closed end 886 of the spool 874 may include a series of perforations (FIG. 8B) that function to allow fluid to flow therethrough, which prevents trapped fluid from interfering with movement during actuation of the spool 874. A cylindrical central shaft 882 with threaded holes on either end connects the spool 886 to a connector 884, which is connected to a drive shaft 820 for moving the spool. The central shaft 882 is coupled to the closed end 886 of the spool 874 by threads 889.

[0109] As explained below, spool 874 can move between a number of positions through linear motion along the longitudinal axis of cylindrical bore 842 to proportionally control fluid flow through valve 800. The actuation mechanism includes motor 816, proximity sensor 824, and drive shaft 820 that connects spool 874 to motor 816. In this embodiment, drive shaft 820 comprises a cylinder with a threaded hole at one end that is coupled to the upper end of connector 884 by screw 887. The distal end of central shaft 882 of spool 874 is coupled to the lower end of connector 884 by screw 885 that is received within the threaded end of central shaft 882.

[0110] Movement of spool 874 is controlled by motor 816, which may be operable to move spool 874 in 0.006 mm increments over a total travel of 17.3 mm. Activation of motor 816 (by controller 834) linearly moves drive shaft 820 along the x-axis shown in FIG. 8A . This linear motion is translated to spool 874 through central shaft 882 and connector 884, resulting in movement of spool 874 along the same x-axis. Proximity sensor 824 functions to detect the home position of drive shaft 820 and generates an output signal for controller 834, which allows spool 874 to be positioned at any number of positions along the longitudinal axis of cylindrical bore 842 to control the flow of fluid through valve 800.

[0111] 9A-C and 10A-F, three positions are illustrated for spool 874. Looking first at FIGS. 9A and 10A-B, spool 874 is in a first position (also referred to as a home position), whereby the open end of spool 874 is adjacent to lid plate 810. In this position, first opening 876 is aligned with first port 836, and second opening 878 is aligned with third port 840. Depending on the configuration of the system in which valve 800 is installed, fluid may be able to flow into third port 840, through second opening 878, through spool 874, and then through first port 836 via first opening 876. Alternatively, fluid may be able to flow into first port 836, through first opening 876, through spool 874, and then through second opening 878 and through third port 840.

[0112] As described above, spool 874 may be actuated to a second position, as shown in Figures 9B and 10C-D. In this position, first opening 876 is still aligned with first port 836, and second opening 878 is aligned with second port 838 and third port 840. Depending on the configuration of the system in which valve 800 is installed, fluid may be able to enter both or either second port 838 and third port 840, enter spool 874 through second opening 878, and exit through first port 836 via first opening 876. Alternatively, fluid may be able to enter first port 836, pass through first opening 876, pass through spool 874, and then pass through second port 838 and third port 840 via second opening 878.

[0113] 9C and 10E-F. In this position, first opening 876 is still aligned with first port 836, and second opening 878 is aligned with second port 838. Depending on the configuration of the system in which valve 800 is installed, fluid may be able to flow into second port 838, through second opening 878, through spool 874, and through first port 836 via first opening 876. Alternatively, fluid may be able to flow into first port 836, through first opening 876, through spool 874, and through second port 838 via second opening 878.

[0114] The position of spool 874 within cylindrical bore 842 may not be limited to the three positions illustrated in Figures 9A-C. Through control of the position of spool 874, the relative fluid flow to / from each of second port 838 and third port 840 may be precisely controlled.

[0115] First opening 876 may be sized to always allow fluid flow between first port 836 and first opening 876 regardless of the position of spool 874 within cylindrical bore 842. Second opening 878 may be sized to allow fluid flow between second opening 878 and only second port 838, only third port 840, or both second and third ports simultaneously, depending on the position of spool 874 within cylindrical bore 842.

[0116] In some embodiments, spool 874 may have a length of 64.1 mm and a diameter of 24.8 mm. First opening 876 may have a length of 32.6 mm, and second opening 878 may have a length of 25.5 mm. First port 836, second port 838, and third port 840 may each have a diameter of 15.3 mm.

[0117] 11A-B, 12A-B, and 13A-B, another embodiment of a valve 900 is shown that is suitable for use in either the first or second fluid system described above. Similar to valve 800, valve 900 includes a valve base 802, a housing 804, a motor mount 814, a motor 816, and a proximity sensor 826. An electronics mount 926 is mounted on the upper surface 802a of the valve base 802. In this embodiment, electronics mount 926 includes four feet 928 that contact the surface 902a at each corner of the valve base 802 and are securely fastened by a suitable method, such as with screws (not shown). Each of the four feet 828 has four legs 930 connected thereto, which extend vertically upward from the foot to a backing plate 932. Backing plate 932 includes two spaced-apart parallel plates 932a and 932b. A controller 934 is securely fixed to the top surface of the backing plate 932a.

[0118] 12A-B, housing 804 includes a first port 836, a second port 838, and a third port 840 that work in conjunction with a cylindrical bore 842 as described above for valve 800. A first port connector 946 is provided to provide a fluid connection between first port 836 and any tubing or conduit used to either receive fluid from or supply fluid to valve 800. First port connector 946 includes a first tubular portion 952 for receiving the tubing or conduit and a second, narrower tubular portion 953 sized to fit within first port 836 of housing 804 with an interference fit.

[0119] Similarly, a second port connector 958 and a third port connector 960 are also provided to provide fluid connections between the second and third ports 838, 840, respectively, and any tubing or conduits used to either receive fluid from or supply fluid to the valve 900.

[0120] A spool 874 is provided that operates in a manner similar to that described above for valve 800 to selectively adjust the proportion of fluid flowing through second and third ports 838, 840.

[0121] Another embodiment of a valve 1000 suitable for use in either the first or second fluid systems described above is shown in Figures 14, 15, and 16A-16D. The valve 1000 includes a valve base 1002, a housing 1004, a motor mount 1014, and a guide rail 1088.

[0122] 14 and 15, the valve base 1002 has a rectangular base 1090 that terminates at its proximal end in a flanged end 1092. A housing mount 1094 having a semi-cylindrical profile sized to receive the housing 1004 runs longitudinally through the center of the mounting base 1002. The semi-cylinder of the housing mount 1094 is closed at its distal end and open at its proximal end.

[0123] The motor mount 1014 has a generally inverted U-shaped cross-sectional profile with a top surface 1096 running longitudinally through its center and terminating in a flanged end 1102, and side surfaces 1098 and 1100. The outer face of the flanged end 1098 contacts the outer face of the flanged end 1092 of the valve base 1002. A motor 816, oriented longitudinally and aligned with the housing 1004, is mounted to the top surface 1096 of the motor mount 1014. In this embodiment, the motor 816 may be a linear DC servo motor, such as the LM0830-015-01 linear DC brushless micromotor manufactured by MicroMo Electronics™.

[0124] A guide rail 1088 is coupled to the motor mount 1014. The guide rail 1088 includes a generally rectangular body 1108 at its distal end with first and second parallel arms 1110 and 1112 extending longitudinally (the z-axis in FIG. 15 ) from the body 1108 and terminating in flanged brackets 1114 and 1116. As shown in FIG. 14 , the sides 1098 and 1100 of the motor mount 1014 are tightly sandwiched by the first and second parallel arms 1110 and 1112 when fitted to the valve 1000. The flanged brackets 1114 and 1116 contact the inner faces of the flanged end 1102, and the guide rail 1098, motor mount 1014, and valve base 1002 are securely fastened together by a suitable method, such as with bolts 1104 and nuts 1106. Running longitudinally down the center of the top surface of the rectangular body 1108 is a guide channel 1118, which is a recessed channel that extends approximately halfway through the depth of the body 1108.

[0125] A housing 1004 is mounted to a housing mount 1094 on the valve base 1002. Referring to Figures 15 and 16A-D, the housing 1004 has a cylindrical body 1120 that is open at its distal end with a cylindrical bore 1042 defined by an inner surface. The distal end is sealed by a removable end cap 1010 that may include a ring 1012 protruding from the outer end to aid in removal. The housing 1004 may be made of a suitable material, such as aluminum. An O-ring 1011 (Figure 15) provides a seal between the cylindrical body 1120 and the end cap 1010. The O-ring 1011 may be made of any suitable material, such as rubber. The cylindrical body 1120 has a first port 1036 extending perpendicularly outward from the cylindrical body 1120, located near the midpoint along the length of the body 1120. The housing 1004 further includes a second port 1038 and a spaced apart third port 1040 on the side of the cylindrical body 1120 opposite the first port 1036. The housing 1004 also includes a central shaft opening 1044 at the proximal end (FIG. 15).

[0126] First, second, and third port connectors 1046, 1058, and 1060 are formed as an integral part of the housing 1004 to provide fluid communication between the first, second, and third ports 1036, 1038, 1040 and any tubing or conduits used to either receive fluid from or supply fluid to the valve 1000. The second and third port connectors 1058, 1060 are angled away from each other to reduce the pressure drop across the valve while providing sufficient clearance between them for attaching tubing or conduits. In one embodiment, the angle Θ between the second and third port connectors 1058, 1060 in FIG. 17A is 43.5 to 44.5 degrees, and optimally is 44 degrees.

[0127] The lower half of the cylindrical body 1120 of the housing 1004 is sized to fit within the housing mount 1094 with the first, second, and third port connectors 1046, 1058, and 1060 positioned to reside within the first, second, and third notches 1122, 1124, 1126, respectively, of the housing mount 1094 (FIG. 15).

[0128] Similar to the other valve embodiments, a spool 1074 is provided mounted within the cylindrical bore 1042 to selectively adjust the proportion of fluid flowing through the second and third ports 1038, 1040. Similar to spool 874, the spool 1074 is hollow, cylindrical, with three openings on its cylindrical surface and sized to fit snugly within the cylindrical bore 1042. A first opening 1076, which is generally rectangular in shape, is located on the curved surface of the spool 1074. A second, smaller, generally rectangular opening 1078 is located on the curved surface opposite the first opening 1076. A third opening 1080 is located at the end of the spool 1074 near the end cap 1010. Similar to spool 874, the closed end 1086 of the spool 1074 may contain a series of perforations. A central shaft 1082, comprising a cylinder with a threaded hole 1130 at its distal end, projects from the center of the closed end 1086. In this embodiment, the center shaft 1082 and the spool 1074 are a single unitary piece. When installed within the housing 1004, the center shaft 1082 protrudes through the center shaft opening 1044 (FIG. 15).

[0129] Similar to spool 874 in valve 800, spool 1074 can move between several positions to control fluid flow through valve 1000 in substantially the same manner as described above (as shown in FIGS. 9A-C). The actuation mechanism for valve 1000 includes motor 816 and drive shaft 820, which couples spool 1074 to motor 816 via connector 1128. In this embodiment, drive shaft 820 and spool 1074 are axially aligned along the z-axis shown in FIG. 15. As shown in more detail in FIG. 16D, connector 1128 has a cylindrical body with openings at either end for receiving center shaft 1082 and drive shaft 820. Drive shaft 820 is secured in place with screws 1129 received in threaded openings in the drive shaft. To secure the spool 1074 to the connector 1128, the connector 1128 may also have holes positioned along its length that align with holes 1130 in the distal end of the central shaft 1082 for positioning a bolt 1132 therethrough. The bolt 1132 is secured with a nut 1134.

[0130] At the distal end of drive shaft 820, a guide rod 1136 is secured by a screw 1138. Guide rod 1136 is generally rectangular with a rounded end and extends downwardly to be received by guide channel 1118. Guide rod 1136 is sized to reside within guide channel 1118 throughout actuation of valve 1000 and helps maintain alignment of drive shaft 820, connector 1128, center shaft 1082, and spool 1074 during actuation.

[0131] The movement of the spool 1074 is controlled by the motor 816. Activation by a controller (not shown) causes the drive shaft 820 to move linearly in the direction indicated by the arrow 1140 in FIG. 16A. This linear motion is transferred to the spool 1074 through the central shaft 1082 via the connector 1128, resulting in linear movement of the spool 1074.

[0132] Another embodiment of valve 1200, similar to valve 1000 and suitable for use in either the first or second fluid systems described above, is shown in Figures 17, 18A-B, and 19A-B. Referring to Figure 17, valve 1200 includes a housing 1204, a motor mount 1214, and a guide rail 1288 formed as a single, continuous valve body 1201. The motor mount 1214 is formed as a single rectangular piece between the proximal end of the housing 1204 and the guide rail 1288. The motor mount 1214 has a flat upper surface for receiving the motor 816.

[0133] The valve disc 1201 further includes a guide rail 1288 formed at the distal end of and coupled to the motor mount 1214. The guide rail 1288 includes a guide channel 1217 extending longitudinally (along the x-axis in FIG. 17 ) at the center of the guide rail 1288. The guide rail 1288 has a flange-like tab 1222 that projects vertically to the top surface of the guide rail 1288, to which a proximity sensor 824 may be attached using a mounting bracket 1223, a bolt 1225, a washer 1226, and a nut 1227. The proximity sensor 824 is configured to detect the position of the drive shaft 820.

[0134] Similar to the housing 1004 of the valve 1000 described above, the housing 1204 has a cylindrical body 1220 with a cylindrical bore 1242 defined by an inner surface and open at the distal end. In this embodiment, the cylindrical bore 1242 has a circular cross-section with flat portions 1243 located at the top and bottom (FIG. 18B). The distal end is sealed with a removable end cap 1010 and an O-ring 1011. The cylindrical body 1220 has a first port 1236 extending perpendicularly outward from the cylindrical body 1220, located near the midpoint of the length of the body 1220. The housing 1204 further includes a second port 1238 and a spaced-apart third port 1240 on the side of the cylindrical body 1220 opposite the first port 1236. The housing 1004 also includes a central shaft opening 1144 at the proximal end (FIG. 18A).

[0135] First, second, and third port connectors 1246, 1258, and 1260 are provided that are arranged and function in a manner similar to the first, second, and third port connectors 1046, 1058, and 1060 of valve 1000 described above to provide fluid communication between the first, second, and third ports 1236, 1238, 1240 and any tubing or conduits used to either receive fluid from or supply fluid to the valve 1200.

[0136] Similar to the other valve embodiments described above, a spool 1274 is provided mounted within the cylindrical bore 1242 for selectively adjusting the proportion of fluid flowing through the second and third ports 1238, 1240. Similar to spool 1074, spool 1274 is hollow, cylindrical in shape with three openings on its surface and sized to fit snugly within the cylindrical bore 1242. A central shaft 1282 comprising a cylinder threaded at each end is connected to the closed end 1286 of the spool 1274 using heat-set threaded inserts 1283. In this embodiment, to ensure proper alignment of the spool within the cylindrical bore during assembly, the top and bottom surfaces of spool 1274 include flattened portions 1275 sized to complement the flattened regions 1243 of the cylindrical bore 1242 ( FIG. 18A ). This arrangement eliminates rotation of the spool 1274 within the cylindrical bore during operation and prevents the center shaft 1282 from slipping off either the spool 1274 or the drive shaft 820. A first opening 1276, which is generally rectangular in shape, is located on the curved surface of the spool 1274. A second, smaller, generally rectangular opening 1278 is located on the opposite curved surface from the first opening 1276. A third opening 1280 is located at the end of the spool 1274 near the end cap 1010. Similar to spool 874, a closed end 1286 of the spool 1274 may contain a series of perforations.

[0137] Similar to spool 874 in valve 800, spool 1274 can move between a number of positions (similar to those shown in FIGS. 9A-C ) to control fluid flow through valve 1200 in substantially the same manner as described above. The actuation mechanism for valve 1200 includes motor 816 and drive shaft 820 that couples spool 1274 to motor 816. In this embodiment, drive shaft 820 and spool 1274 are axially aligned along the z-axis shown in FIG. 18A . The distal threaded end of center shaft 1282 is coupled to the threaded center of drive shaft 820.

[0138] The actuation mechanism for valve 1200 may also include a proximity sensor 824 that functions to detect the position of drive shaft 820 (and consequently spool 1274) and generate an output signal for a controller (not shown), which allows spool 1274 to be positioned at any number of positions along the longitudinal axis of cylindrical bore 1242 to control the flow of fluid through valve 1200.

[0139] At the distal end of drive shaft 820, guide rod 1262 is secured by screw 1264. Guide rod 1262 extends downward into guide channel 1217. Guide rod 1262 is sized to remain within guide channel 1217 throughout the actuation of valve 1200 and helps maintain alignment of drive shaft 820, center shaft 1282, and spool 1274 during actuation.

[0140] The movement of the spool 1274 is controlled by a motor 816. Activation of the motor by a controller (not shown) causes the drive shaft 820 to move linearly in the direction indicated by arrow 1241 in FIG. 19A. This linear motion is transferred to the spool 1274 through a central shaft 1282, resulting in linear movement of the spool 1274.

[0141] 20, 21, 22A-C, 23, and 24, another embodiment of a valve 1300 is depicted that is suitable for use in either the first or second fluid systems described above and includes a valve base 1302, a motor 1316, a housing support 1303, a housing 1304, and a lid 1310.

[0142] 20 and 21, the valve base 1302 may include a rectangular plate 1302a and a motor mount 1314. The motor mount 1314 is a hollow cylinder protruding from the center of the rectangular plate 1302a that is open at the top to receive a motor 1326 therein. In this embodiment, the motor 1316 may be a brushless DC servo motor.

[0143] 21 , housing support 1303 is coupled to motor 1316 and secured by screws 1305 located in threaded holes on the top surface of motor 1316. Housing support 1302 includes a lower housing mounting plate 1307 and an upper housing mounting plate 1309 connected by a pair of upwardly extending lower support arms 1321. Lower housing mounting plate 1307 is a round plate with an opening in the center to allow an actuation mechanism to fit through it. Similarly, upper housing mounting plate 1309 has a generally circular shape and is sized to follow the outer profile of housing 1304 and includes a central opening. At opposite points along the periphery of the upper housing mounting plate 1309 are two upper support arms 1313 that rise vertically with horizontally outwardly projecting flanged ends 1321 that contact corresponding flanges 1315 on the housing 1304 to provide additional support. The flanged ends 1315 and flanges 1315 are securely fastened together with bolts 1317 and nuts 1319.

[0144] In this embodiment, housing 1304 may have a cylindrical shape with an opening at the top that may be reversibly sealed by lid 1310 and O-ring 1311. Lid 1310 may include a ring 1312 protruding from the top surface to aid in removal. Housing 1304 further includes a first port 1336, a second port 1338, and a third port 1340 positioned on the outer cylindrical surface. Second and third ports 1338, 1340 are positioned adjacent to each other, while first port 1336 is positioned on opposite sides of housing 1304.

[0145] First, second, and third port connectors 1346, 1358, and 1360, respectively, formed as an integral part of housing 1304, are provided to provide fluid connections between first port 1336, second port 1338, and third port 1340 and any tubing or conduits used to either receive fluid from or supply fluid to valve 1300.

[0146] The inner surface of the housing 1304 defines a cylindrical bore 1342 through which fluid may flow between the first, second, and third ports 1336, 1338, and 1340. To selectively adjust the proportion of fluid flowing through the second and third ports 1338, 1340, a spool 1374, sized to fit within the cylindrical bore 1342 and shown in more detail in FIG. 24, is provided. The spool 1374 has a hollow cylindrical body closed at one end 1386, with a first rectangular opening 1376 in a curved surface and a second, smaller rectangular opening 1378 located on the opposite curved surface of the spool 1374. A third opening 1380 is located at the cylindrical upper end of the spool 1374. At the center of the bottom surface of the closed end 1386 protrudes an actuation mount 1379, which provides a connection point for the actuation mechanism of the valve 1300.

[0147] Spool 1374 can move between several positions through rotational movement about the central vertical axis of cylindrical bore 1342 (the y-axis in FIG. 21 ) to selectively adjust the proportions of fluid flow among first, second, and third ports 1336, 1338, and 1340. The actuation mechanism includes a motor 1316 and a drive shaft 1320 coupled using a connector. In this embodiment, to provide a secure, backlash-free connection between spool 1374 and motor 1316, the connector is an Oldham coupling 1381 including a disc 1383 sandwiched between upper and lower connecting hubs 1385 and 1387. One example of an Oldham coupling suitable for use in valve 1300 is the MOST19-8-A and MOCT19-4-A connecting hubs and OD12 / 19-AT coupling disc manufactured by Rotoprecision Inc. Upper connection hub 1385 is attached to drive mount 1379 via a set screw (not shown) at flat edge 1379a of drive mount 1379. Lower connection hub 1387 is attached via an integral clamping mechanism (not shown).

[0148] Movement of the spool 1374 is controlled by a motor 1316, which drives rotation of the spool 1374 about their central axis via an Oldham coupling 1381. Referring to FIGS. 22A-C, three positions for the spool 1374 are illustrated. Looking first at FIG. 22A, the spool 1374 is in a first position, whereby the first opening 1376 is aligned with the first port 1336 and the second opening 1378 is aligned with the second port 1338. Depending on the configuration of the system in which the valve 1300 is installed, fluid may be able to flow into the second port 1338, through the second opening 1378, through the spool 1374, and then through the first port 1336 via the first opening 1376. Alternatively, fluid may be able to flow into the first port 1336, through the first opening 1376, through the spool 1374, and then through the second port 1338 via the second opening 1378.

[0149] As described above, spool 1374 may be actuated to a second position, as shown in FIGURE 22B. In this position, first opening 1376 is aligned with first port 1336, and second opening 1378 is aligned with second port 1338 and third port 1340. Depending on the configuration of the system in which valve 1300 is installed, fluid may be able to flow into second port 1338 and third port 1340, through second opening 1378, through spool 1374, and through first port 1336 via first opening 1376. Alternatively, fluid may be able to flow into first port 1336, through first opening 1376, through spool 1374, and through second opening 1378 to second port 1338 and third port 1340.

[0150] As described above, the spool 1374 may be actuated to a third position, as shown in FIGURE 22C. In this position, the first opening 1376 is aligned with the first port 1336, and the second opening 1378 is aligned with the third port 1340. Depending on the configuration of the system in which the valve 1300 is installed, fluid may be able to flow into the third port 1340, through the second opening 1378, through the spool 1374, and through the first port 1336 via the first opening 1376. Alternatively, fluid may be able to flow into the first port 1336, through the first opening 1376, through the spool 1374, and through the third port 1340 via the second opening 1378.

[0151] When introducing elements of the invention or aspects thereof, the articles "a," "an," "the," and "the" are intended to mean that there are one or more of the elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0152] Of course, the above-described embodiments are intended to be illustrative only and not limiting in any way. The above-described embodiments of carrying out the invention are susceptible to many modifications of form, arrangement of parts, details, and order of operation. Accordingly, the invention is intended to encompass within its scope all such modifications.

Claims

1. a first conduit having a first end and a second end; and a first control valve and a second control valve, each control valve having a first port, a second port, and a third port, and each control valve further comprising a spool configured to selectively adjust the rate of fluid flow through the second port and the third port of the respective control valve; Equipped with the first port of the first control valve is configured to connect to an intake port of a pump, the second port of the first control valve is configured to connect to the second end of the first conduit to draw fluid from the first conduit, the first port of the second control valve is configured to connect to an output port of the pump, and the second port of the second control valve is configured to connect to the second end of the first conduit to supply fluid to the first conduit. Valve assembly.

2. 10. The valve assembly of claim 1, wherein each control valve comprises an actuator for actuating the spool of the respective control valve.

3. 3. The valve assembly of claim 2, wherein the actuator for each control valve comprises a servomotor.

4. 4. The valve assembly of claim 2 or claim 3, wherein the spool of each of at least one of the first control valve and the second control valve is a sliding spool, and the actuator of the at least one control valve is a linear actuator.

5. 4. The valve assembly of claim 2 or claim 3, wherein the spool of at least one of the first control valve and the second control valve is a rotary spool, and the actuator of the at least one control valve is a rotary actuator.

6. 5. The valve assembly of claim 4, wherein the linear actuator of the at least one control valve comprises a drive shaft coupled to the sliding spool of the respective control valve for positioning the sliding spool.

7. 7. The valve assembly of claim 6, wherein the linear actuator of the at least one control valve comprises a proximity sensor for determining the position of the drive shaft of the respective control valve.

8. 8. The valve assembly of claim 7, wherein the actuator of the at least one control valve comprises a controller for controlling movement of the drive shaft of the respective control valve based on an output signal from the proximity sensor of the respective control valve.

9. 9. The valve assembly of claim 6, wherein the drive shaft of the linear actuator of the at least one control valve and the sliding spool of each of the control valves are axially aligned along an axis of the drive shaft.

10. 10. The valve assembly of claim 9, wherein the drive shaft of the linear actuator of the at least one control valve comprises a guide rod configured to maintain axial alignment of the drive shaft of the respective control valve.

11. 11. The valve assembly of claim 6, wherein the linear actuator of the at least one control valve comprises a connector coupled to the drive shaft and the sliding spool of the respective control valve.

12. 12. The valve assembly of claim 11, wherein the drive shaft of the linear actuator of the at least one control valve and the sliding spool of each control valve are vertically stacked.

13. The at least one control valve: opposing ends and a cylindrical bore extending between the opposing ends; the first port of each of the control valves located on a first side of the bore; and the second port of each of the control valves and the third port of each of the control valves located on a second side of the bore; a housing including: the spool of each of the control valves is slidable within the bore and includes a transversely extending conduit including a first opening facing the first side of the bore and a second opening facing the second side of the bore; the first opening is sized and positioned to allow fluid communication with the first port; the second opening is sized and positioned to selectively allow fluid communication with the second port and the third port by sliding the spool within the bore; The valve assembly of any one of claims 1 to 4 and 6 to 12.

14. 14. The valve assembly of claim 1, comprising a three-way connection at the second end of the first conduit for connecting the second end of the first conduit to the second port of the first control valve and the second port of the second control valve, respectively.

15. 15. The valve assembly of claim 14, wherein the three-way connection comprises a three-way valve, a T-junction, or a Y-junction.

16. a sealed chamber for containing a lung within the sealed chamber, the sealed chamber having a pressure port; and a first pump having an intake port and an output port; 16. The valve assembly according to any one of claims 1 to 15, connected to the intake port and the output port of the first pump, wherein the first end of the first conduit of the valve assembly is sealingly connected to the pressure port of the sealed chamber; a first fluid system for applying a variable first pressure to an outer surface of the lung within the sealed chamber through the pressure port to cause the lung to breathe, A ventilator comprising:

17. a second fluid system for applying and maintaining a second pressure within the airways of the lung, the second fluid system comprising a second conduit having a first end and a second end, the second end of the second conduit being connectable to a trachea of ​​the lung through the sealed chamber; 17. The ventilator of claim 16, further comprising:

18. 18. The ventilator of claim 17, wherein the second fluid system further comprises a second pump for supplying pressurized fluid to the second conduit and for maintaining the second pressure within the second conduit.

19. 19. The ventilator of claim 17 or claim 18, further comprising a control system configured and connected to control the first fluid system and the second fluid system to cause the lungs to breathe.

20. The control system sensors for sensing pressure and fluid flow within the first conduit and the second conduit; and a processor for processing the sensed pressures and fluid flow rates and for determining a pumping speed for each pump and a rate of fluid flow through the second and third ports of each of the control valves.

20. The ventilator of claim 19, comprising:

21. a third conduit connecting the third port of the second control valve of the first fluid system to the second conduit of the second fluid system; and a third control valve in the third conduit for regulating fluid flow from the first control valve to the second conduit through the third conduit; 21. The ventilator of any one of claims 17 to 20, further comprising:

22. 20. The ventilator of claim 18, wherein the first pump and the second pump each comprise a blower.

23. 23. The ventilator of any one of claims 16 to 22, comprising a fluid filter within each of the first conduit and the second conduit.

24. 24. The ventilator of claim 16, further comprising a fluid filter coupled to the third port of at least one of the first control valve and the second control valve.

25. 25. The ventilator of any one of claims 16 to 24, comprising a fluid filter coupled to an input port of the second pump.

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