HK1123511B - Apparatus for delivery of pressurised gas - Google Patents

Description

Device for delivering compressed gas

Technical Field

The present invention relates to systems, devices and methods for delivering breathable gas. In particular, the present invention relates to systems, devices and methods for delivering gases at constant or variable flow rates, pressures and humidities. More particularly, the present invention relates to devices and methods for delivering breathable gas to a mask to treat respiratory disorders.

Background

Many devices can deliver breathable gas, including air, to a patient to treat disordered breathing, and in particular sleep disordered breathing. For example, in the treatment of sleep apnea, including obstructive sleep apnea, air is typically delivered at Continuous Positive Air Pressure (CPAP), wherein the air is continuously supplied to the airway of a sleeping patient through a mask at a pressure greater than ambient pressure to keep the airway of the patient open for effective breathing.

For the sustained therapeutic effect of compressed air, it is important to deliver air and other gases at pressures and flow rates appropriate for the desired breathing pattern. During treatment, this delivery of gas should not induce the sensation of "blowing air". Systems known in the art that include a gas delivery device, which typically humidifies the gas for comfort, include various combinations of fans, air conduits, masks, and mask assemblies. The gas delivery device may be controlled by circuitry and computer software to deliver gas to the mask through the air conduit at a desired flow rate and pressure.

Prior art gas delivery systems, methods, and devices generally include a limited number of desirable features. For example, the gas may be delivered at only one flow rate or a limited number of multiple flow rates. Similarly, the gas may simply be delivered as compressed air, and treatment with compressed air of insufficient humidity may dry the patient's respiratory tract, creating discomfort. The devices that deliver the gas can be large and bulky and thus difficult to maneuver. It is known in the art that fans used in devices can generate noise and thus use of such devices can interfere with the sleep of a patient. Devices are known in the art in which the flow rate is controlled by varying the motor speed. Such devices are limited in their efficacy in controlling flow rate through such a rate: with this speed, the pressure change can be influenced by the power of the motor.

What is needed is a gas delivery system and method for delivering gas that includes a gas that is relatively easy to manipulate, operate, quiet, and deliver a suitable humidity at a desired flow rate and pressure. In addition, the gas delivery system should be relatively easy to manufacture and transport. The gas delivery system should be capable of switching rapidly between pressure levels to accommodate exhalation and respiratory changes.

The gas delivery systems described herein include CPAP, VPAP (variable positive air pressure), BiPAP (bi-level positive air pressure), or APAP (automatic positive air pressure) systems and devices, all of which describe the flow rate and pressure of gas delivered by the device or system. For example, during patient exhalation, BiPAP switches to low airflow at the appropriate time so that the patient can breathe more comfortably without having to inhale an "air force". Additionally, the acronyms used in this document to describe each element and their meanings are provided in table 1. In this document, the terms "including" and "comprising" are used in a non-limiting sense.

Brief description of the drawings

FIG. 1 shows a view of a compressed gas delivery system;

FIG. 2 shows a view of a motor controller of the gas delivery device;

FIG. 3 illustrates a motor current sensing circuit;

FIG. 4 shows a block diagram of a motor controller;

fig. 5 shows the operation of the motor controller PWM;

FIG. 6 illustrates a humidifier component of the gas delivery device;

FIG. 7 shows a functional block diagram of the electronic subsystem of the gas delivery device with a keypad for controlling operation;

FIG. 8 shows a perspective view of a gas delivery device;

FIG. 9 shows a side view of the blower, partially in section;

FIG. 10 shows a side view of the blower, partially in section;

FIG. 11 shows a gas filter in perspective view;

FIG. 12a shows a top perspective view of a gas conveying device with a water reservoir positioned outside the gas conveying device;

FIG. 12b shows a top perspective view of the gas conveying device with a water reservoir operatively positioned inside the gas conveying device;

FIG. 13 shows a side view in longitudinal section of a gas delivery device; and

fig. 14 shows a top view of a blower within a sound-proof housing of a gas delivery device.

Summary of The Invention

It is an object of the present invention to provide a simple humidification system for compressed gas. It is a further object of the present invention to provide a gas delivery system that is relatively easy to use. It is another object of the invention to provide a method of delivering humidified gas to a subject through a conduit.

The invention provides a gas delivery system including a humidifier assembly including a movable water reservoir. For the present invention, the humidity level of the gas passing through the water may be selected by the device user. The invention advantageously has the function that the variation of the set humidity level can be controlled by adjusting the temperature of the water in the reservoir. The water reservoir in a gas delivery device constructed in accordance with the present invention can be easily removed for cleaning or replacement.

The invention may include a pressure sensing device for detecting gas pressure at a location near where a conduit for delivering compressed gas from a gas delivery device engages the device. Advantageously, this arrangement allows the pressure of the gas delivered through the conduit to be calculated as a function of a variable including the detected pressure, the function taking into account parameters of the mask type and the length of the conduit.

It is another object of the present invention to provide a gas delivery device and system that is capable of making rapid changes in gas pressure and flow rate to effectively provide gas to the airway of a patient while accommodating the breathing pattern of the patient. These system elements cooperate to reduce pressure fluctuations at the patient's mask as the patient breathes during treatment. The present invention provides a gas delivery system that is controlled by computer software running on a microcontroller. According to the present invention, the outputs from the pressure-measuring sensor, the flow rate sensor, the temperature sensor and the humidity sensor are conveniently converted to digital values by an analog-to-digital converter (ADC) for subsequent signal processing. For the present invention, the microcontroller sets the desired instantaneous pressure in the conduit and mask by adjusting the motor speed of the fan according to computer software. The present invention provides a motor speed control method in which the signal from a rotor position sensor is digitally processed to determine the current speed, position and three phase winding drive signals. With the present invention, the motor has a sufficiently small inertia that the gas delivery device can respond quickly to changes in the predetermined gas pressure setting.

The humidification system includes a reservoir for humidifying the delivered gases that engages and seals with the conduit when the device cover is in the closed position. The present invention also provides a reservoir that engages a heating plate when the device lid is in the closed position. The heat patch biases the water container into engagement with the heat patch. The invention also provides a water container integrated with the gas supply system. The present invention provides a port to the reservoir that combines an air inlet and an air outlet, which advantageously simplifies refilling of the reservoir. The simple structure of the water reservoir, preferably formed from a polymer that can be blow molded, advantageously reduces the cost of manufacturing the water reservoir. It is further advantageous that the reservoir can be easily cleaned or replaced.

The present invention provides a tight isolation chamber surrounding a blower so that sound emitted from the blower can be effectively isolated. Preferably it is formed of metal, more preferably it is formed by zinc die casting, preferably the walls of the compartment are generally thicker than 1.6 mm. The integral components of the isolation chamber include one or more plenums that effectively attenuate sound propagating along the air path. In addition, the entire isolation chamber advantageously acts as a helmholtz resonator, the frequency of which can be modified by providing the inlet and/or outlet channels with preferred dimensions. Preferably, the inlet and/or outlet passages are generally annular in cross-section and of sufficient length to minimize the resonant frequency of the isolation chamber without causing excessive flow restriction.

For the present invention, the configuration of the components of the gas delivery device allows the gas delivery device to be disposed in any suitable orientation, i.e., alternative mounting orientation, relative to horizontal or vertical. Advantageously, the present invention provides an embodiment that includes a vertically disposed gas delivery device so that the device can be mounted on a wall.

Advantageously, with the present invention, the gas delivery device comprises an air filter which may be housed within a removable transparent housing, the dirty side of the filter being visible through the transparent housing.

The present invention also provides a Graphical User Interface (GUI) to facilitate construction, assembly of the device, and patient history feedback. According to the invention, the GUI may include an alarm clock function.

For the present invention, device patient specific structure and sleep study data may be recorded on removable SD card media. This feature provides flexibility in the set-up of the invention and subsequent analysis of data by the remote laboratory of the invention, since the patient only needs to transfer the SD card.

In one aspect, the present invention provides an apparatus for delivering breathable gas to a subject, the apparatus comprising: a blower for delivering compressed gas to a reservoir to humidify the gas; a heater; a housing for accommodating the blower and the reservoir; an air inlet and an air outlet, both of which are coupled to a port in the reservoir; and a duct for guiding the gas from the gas outlet to the object.

In another aspect, the present invention provides an apparatus for delivering breathable gas to a subject, the apparatus comprising: a blower for delivering compressed gas, the blower being located within the sound-deadening housing; a housing for accommodating the blower and the reservoir; the heater is used for heating the water in the reservoir; an air inlet and an air outlet; a gas filter housed within the movable transparent housing; and a duct for guiding the gas from the gas outlet to the object.

In another aspect, the present invention provides an apparatus for delivering breathable gas to a subject, the apparatus comprising: a blower for delivering compressed gas; a housing for accommodating the blower; a heater; an air inlet and an air outlet; a conduit for guiding the gas from the gas outlet to the object; and at least one plenum and at least one resonating device adjacent to the blower. In this aspect, the apparatus may include a reservoir and a heater to heat water in the reservoir.

In another aspect, the present invention provides an apparatus for delivering breathable gas to a subject, the apparatus comprising: a blower for delivering compressed gas; the water storage tank is used for humidifying the gas; a heater; a housing for accommodating the blower and the reservoir; an air inlet and an air outlet; and a conduit for directing gas from the gas outlet to an object, wherein the apparatus can be positioned for operation at any suitable angle from a substantially horizontal to a substantially vertical orientation without leakage of liquid from the reservoir.

In another aspect, the present invention provides an apparatus for delivering breathable gas to a subject, the apparatus comprising: a blower having an outlet for delivering compressed gas, the blower including a motor chamber, two outlet gas passages, and a valve chamber, the blower including means for rapidly changing the pressure or flow rate of the gas; a housing for accommodating the blower and the reservoir; an air inlet and an air outlet; a gas filter housed within the movable transparent housing; and a duct for guiding the gas from the gas outlet to the object.

In any of the above aspects, the conduit may be comprised of concentric conduits for gas inflow and outflow. Preferably, the inner conduit provides the inlet gas.

Preferably, the means for varying the pressure or flow rate of the gas is at least one impeller. Preferably, the apparatus comprises time signalling means for a user to determine the time of the apparatus. Preferably, the signal transmission means is a clock.

In another aspect, the present invention provides a method for controlling a motor of a blower in a gas delivery device, the method comprising the steps of: a determination step of determining a rotational position of the impeller; a determining step of determining a speed of the impeller; and an adjusting step of adjusting a timing of winding energization for controlling a speed of the impeller.

In another aspect, the present invention provides a method of delivering breathable gas to a subject, the method comprising the steps of: a compression step, compressing the ambient gas by adopting an impeller; a humidifying step of humidifying the ambient gas; a sending step of guiding the humidified gas to an airway of a subject; wherein the compressing step comprises: a detecting step of detecting the position of the impeller by using a sensor device. Preferably, the sensor device used in the method is a hall effect sensor.

Detailed description of the drawings and the most preferred embodiment

The present invention is more readily understood with reference to the accompanying drawings. It is to be understood that the drawings are for purposes of illustrating embodiments of the invention and that the scope of the invention is defined by the claims to include other embodiments not shown. FIG. 1 illustrates various typical elements of a compressed gas delivery system. The invention comprises the following steps: the gas is drawn into the gas delivery device through a replaceable filter system by a motor and blower assembly housed within a noise dampening housing, thereby enabling the system to operate more quietly. A flow sensing device placed in series with the gas channel may be used to detect the gas flow. Additional aspects within the scope of the invention are included in the following description.

Outer casing

The following elements are more clearly understood in comparison with fig. 8 to 14. The outer housing of the gas delivery device comprises: an upper case 1, a lower case 2, a first side plate 3, a second side plate (not shown) opposite to the first side plate, and a cover 4. The upper and lower housings may be joined by suitable joining means. Preferably, the engagement means is a screw. Engagement of the upper and lower covers positions the first and second side panels to form a relatively leak-proof seal. In the engaged position, the outer housing is relatively strong against the ingress of water poured on top of the gas delivery device, regardless of the orientation of the housing. The cover is engaged with the upper case by cover engagement means. Preferably, the lid engagement means is a pivot point snap means (snap-fit at the pivot point means). The pivot point means may be any suitable pivoting means such as a hinge or hinge pin. Alternatively, and more advantageously, the slewing device may be a mechanism comprising a mechanism in which the instantaneous point of rotation is not fixed relative to the housing. Examples of such mechanisms include, but are not limited to, four-bar linkage mechanisms. When engaged in the closed position, the lid may be position locked by a lid locking mechanism 5. Preferably, the lid locking mechanism is a latch. Preferably, the latch is spring actuated. Preferably, the lid is also spring-actuated so that it can open when the lid latch is disengaged. In the case of spring actuation, the spring that actuates the lid preferably includes a rotational damper to produce a smooth opening action for the lid and avoid a "jerky" spring action that might otherwise occur. The pivot point may be located at the top of the housing or it may be located at the back of the housing.

For the present invention, a User Interface (UI) is located on the upper housing. Preferably, the UI is formed by a transparent lens 6, a sealing means between the upper housing and the lens, and a flexible keyboard 7. Preferably, the sealing means is a gasket. Preferably, the keypad comprises at least one button. The lens is engaged with the upper housing by suitable engagement means. Preferably, the lens engaging means is a snap-fit arrangement on each side of the lens. Alternatively, the lens engaging means may be an adhesive tape. Most advantageously, the lens allows a user of the gas delivery device to see the display that conveys information to the user through the outer housing. Another advantage of the lens is that: it engages the flexible button keypad in a fixed position. Another advantage of the engagement of the lens is the seal that prevents water from flowing into the upper housing through the screen or button holes. Preferably, the flexible button keypad is formed of silicon, thereby allowing a gas delivery device user to advantageously transmit commands to the gas delivery device.

Air filter

For the present invention, the air filter includes a front case 8, a rear case 9, and at least one primary filter 10, as shown in fig. 11. Preferably, the housing material is transparent. Preferably, the air filter includes a secondary filter 11. For the present invention, the front housing is joined with the rear housing to form a channel that includes at least a primary filter and preferably a secondary filter. Preferably, the engagement means comprises a snap-fit arrangement. In operation of the gas delivery device, the engagement of the front and rear housings that form the passageway requires that the gas delivered by the gas delivery device must pass through the filter media. The filter media may include primary media and secondary media. The filter front housing includes a plurality of apertures for allowing gas to flow into the primary filter and into contact with a surface of the primary filter media to effect filtration. Preferably, the cross-sectional area of the holes is greater than 400mm²To avoid restricting inflowA primary filter. The filter rear housing includes an aperture that receives the connector fitting of the upper housing, which provides a good seal when engaged. Preferably, the connector fitting is a male tube. The filter engages the upper housing below the cover. It would be further advantageous to allow manipulation of the filter housing to remove and replace the filter. For the utilization of a gas delivery device constructed in accordance with the present invention, replacement of the filter will ensure that the intake air is filtered.

The primary filter media enables the removal of large dust particles from the gas, while the intermediate filter media is used to remove smaller particles. For the present invention, a range of medium effect filter media are used. Examples of such media include media suitable for removing pollen, bacteria, smoke air pollution and viruses. It should be understood that the scope of the filter media is not limited to the above list.

Blower/motor

For the present invention, the blower may include components of different configurations as shown by way of example herein. It should be understood that other configurations are within the scope of the claimed invention.

In the first embodiment of the present invention shown in fig. 9, the blower is formed of a top case 12, a bottom case 13, and a partitioning partition (partition plate) 14. These elements are engaged with screws or other engagement means to make a hermetic seal and form the blower chamber, the motor chamber, the two outlet air ducts, and the valve chamber. The blower chamber houses an impeller 16, the impeller 16 being mounted on a shaft by means of bearings 17 at each end. Preferably, one bearing is press fit into the top housing and the other bearing is located in the bottom housing so that it moves axially within the housing. Preferably, the helical spring conveniently maintains an effective axial preload on both bearings. Preferably, these bearings are lubricated with a low noise lubricant. The impeller 16 may have a series of fins on its top surface to move air as the impeller 16 rotates. For the present invention, between each fin is a small gap between the top and bottom surfaces of the impeller. In combination, these features cause a large portion of the air flow generated by the impeller to exit the blower chamber into the top outlet stack (formed by the top casing and the partition) and create a higher pressure in this stack. These small holes also allow some air to flow into the bottom outlet air passage (formed by the bottom housing and the baffle) and create a reduced pressure in this air passage. Within the valve chamber, a valve member 18 regulates the amount of air flowing out of each of the top and bottom outlet air passages. Most advantageously, this valve 18 is able to vary the pressure of the total outlet air very rapidly without the need for a motor to vary the speed of the impeller. The motor compartment contains the motor mechanism and electronics which are held securely in place by the bottom housing 13 and the partition 14.

In a second embodiment of the invention, as shown in fig. 10, the blower comprises a top housing 20 and a bottom housing 21, the top housing 20 and the bottom housing 21 being joined using suitable joining means to form a gas-tight seal. Preferably, the engagement means comprises a screw. The joined housings form a blower chamber, a motor chamber, and an outlet passage. An impeller 24 is located within the blower chamber, the impeller 24 having two bearing sleeves 23 and a magnet 25, wherein the two bearing sleeves 23 are mounted to either end of the blower chamber and the magnet 25 is mounted to the middle of the central axis of the chamber. The top bearing sleeve 23 is pressed into the top housing and the bottom bearing is held radially vertically in the bottom housing by the impeller spring 22. Preferably, the impeller and shaft 24 are integrally molded from a glass-filled polymer. Alternatively, they may be fully molded onto the metal shaft as a polymer.

The top housing includes an air inlet located above the blower chamber allowing air to enter the blower chamber. The impeller has a series of fins on its top surface designed to move air to the outlet as the impeller rotates. Such gas movement causes a pressure rise at the outlet which can be adjusted by the speed at which the impeller rotates. The bottom surface of the impeller is positioned adjacent to a wall on the bottom housing, advantageously forming a motor compartment. Within the motor chamber, the motor windings 27 and electronics 28 are securely positioned in place by snap fit or other suitable means and provide the power to drive the impeller in rotation.

Preferably, the motor utilizes an annular magnetic core without magnetic joints. Three phase windings are used in a star configuration, which are supplied with sinusoidal modulated power (SPWM) to minimize torsional excitation. Preferably, the rotor is formed entirely of precision molded plastic, thereby most advantageously avoiding the need for an internal metal shaft and dynamic balancing. For the present invention, the electrical commutation is phased by a Hall effect sensor positioned adjacent the rotor magnet.

Sound insulation shell

For the present invention, in one embodiment, as shown in fig. 13 and 14, the sound-insulating housing is comprised of an upper housing 56, a lower housing 57, a sealing gasket 58, two partition walls 59, an inlet tube 60, an outlet tube 61, a flexible blower connector 62, and the blower described herein. Preferably, the upper and lower housings are molded or cast from a dense material to reduce sound transmission from the interior of the housing to the exterior, thereby containing sound therein. Preferably, the dense material is zinc or a mineral filled plastic. The upper and lower housings are joined by joining means so as to position the two partition walls, the inlet pipe and the outlet pipe and press the sealing gasket around the periphery to hermetically seal. Preferably, the engagement means is a screw. This joining of the housings according to the invention forms three chambers, namely a blower chamber, a primary sound chamber and a secondary sound chamber. The blower is located within the blower chamber. Preferably, the blower is mounted on two springs, a top spring 64 and a bottom spring 65, which will ensure that the blower has a low resonant frequency. The spring serves to reduce the transmission of vibrations from the blower to the sound-insulating housing. Preferably, to increase the noise isolation effect, the flexible sheet 66 is positioned above the top spring and below the bottom spring. At the blower outlet, a flexible tube secures the outlet to outlet tube 61. Preferably, the flexible tube has corrugated sides. In this embodiment, the flexible tube forms a portion of the sealing gasket 58. Preferably, the flexible tube is molded from a TPE material. Alternatively, it may be a separate part. The partition wall 59 separates the chambers and reduces sound transmission from one chamber to the next. Preferably, the partition walls may comprise a tube extending to the next chamber. The function of this duct is to convey all the air flow between the chambers. Preferably, the end of the tube is a small distance from the opposite wall of the next chamber, sufficient not to restrict the air flow. Preferably, the opposing walls are covered with sound dampening foam 59 or other suitable material to inhibit sound from propagating to the tube and thus between the chambers.

Humidifier

The invention comprises a humidifier included in a gas delivery device that performs both gas delivery and humidification functions, thereby cooperating in the operation of the device. As shown in fig. 12, the humidifier includes: a water reservoir 30, a gas conduit connection 33, a gas seal 28, a set of heating fins 31 with internal ceramic heaters, and a reservoir heat conductor 32. In operation, the humidifier is concealed under the lid 4.

Preferably, the water reservoir 30 is formed from blow molded thermoplastic. The cistern surface comprises straight, flat sections corresponding to the rails 36 on the receiving surface or upper housing 1. In operation, these rails ensure that: the reservoir is correctly placed in the apparatus and is held firmly in place. In a preferred embodiment of the invention, the water reservoir cannot be inserted into the device in any other position than the correct one. In a suitable position, the reservoir heat conductor 32 is coupled to the upper heat plate 31 by operation of a biasing means 38, the biasing means 38 biasing the heat plate in the direction of the reservoir to ensure efficient heat transfer between the heater and the water. Preferably, the biasing means 38 is a heat patch spring. Advantageously, for the present invention, the metal lid may be of the type commonly used in food packaging. For the present invention, a handle 38 may extend from the reservoir. In such an embodiment, the handle 38 preferably includes at least one integral hinge 39. Preferably, the integral hinge is moulded flat so that when the lid 4 is released from the open position, the handle automatically springs out to facilitate finger access. The handle 38 also facilitates movement of the cistern from the device to the domestic faucet.

In operation, the reservoir 30 is filled with water and replaced in place in the apparatus, allowing the lid 4 to be engaged in the closed position. The gas conduit connector 33 is inserted into the cover 4 so as to move and hinge as one unit. Once the lid 4 is engaged, the outer surface of the gas conduit connector 33 is also positioned to simultaneously engage the reservoir gas seal 28 at the reservoir opening 29. In operation, disengagement of the lid 4 also simultaneously disengages the gas conduit connector 33 from the water reservoir, thereby enabling quick and easy access and removal of the water reservoir 30.

Preferably, the gas conduit connection 33 is connected to a flexible gas conduit 40, so that compressed gas is supplied to the gas inlet 35 and a gas-tight seal is maintained at both ends of said flexible gas conduit, while the lid 4 is in the open or closed position.

The most advantageous aspect of the invention is a hole 29 for the inflow and outflow of gas from the gas delivery device. For the present invention, the gas conduit joint 33 includes adjacent gas inflow conduit 35 and gas outflow conduit 34. Preferably, the gas flow conduits are concentric tubes. Preferably, the gas inflow conduit 35 is located inside the gas outflow conduit 34. In operation, compressed dry gas flows from the gas inflow conduit 34 into the water reservoir 30 to come into contact with the warm water surface 42 so that the gas becomes humidified before flowing through the gas outflow conduit 34.

The present invention includes a small water reservoir that is large enough to hold enough water to humidify enough breathing gas for a patient to sleep overnight. The reservoir is configured to engage a surface of a heater with a heating surface of the heater, wherein the heater is typically disposed at an acute angle of approximately 45 degrees. The location of the apertures 29 on the surface generally parallel to the surface engaging the heating surface allows the gas delivery means to be positioned in a horizontal orientation, such as on a bedside table, or in a vertical orientation, such as on a wall, or in any convenient intermediate orientation, without compromising the operation of the apparatus and its humidifier. More advantageously, changing the angle of the apparatus by 20 degrees in any direction from the horizontal or vertical orientation will not result in any leakage of water from the reservoir 30.

Fig. 6 is a schematic diagram illustrating the operation of a humidifier constructed in accordance with the present invention. The temperature of the heater chip is the only controlled variable in setting the humidity of the gas. The duty cycle of the heating element is used to control the heater chip temperature. An optically coupled zero-crossing triac driver is used to turn the triac on and off under the control of the microcontroller. This optical coupling includes isolation of the triac driver output (on the mains voltage line) from the microprocessor control signal. The zero cross switch reduces EMI generated by the triac.

For the present invention, a computer program running on the microcontroller controls the heater chip temperature to produce a user selected humidity level. In one embodiment, the gas delivery device includes an ambient air temperature sensor and a plurality of user requested humidity levels. For the present invention, the air temperature and heat patch input and the air flow rate are used by the computer program to set the heat patch temperature. Preferably, the gas delivery device includes a humidity sensor for the ambient air, so that more precise control of humidity is possible.

For the present invention, the humidifier comprises a mains-powered heater, preferably switched by a triac, a temperature regulating device connected to a heating plate, and a thermal element connected to the heating plate to provide temperature feedback to the software. An ambient air temperature sensor is used to help determine the water temperature at the user selected humidity, and a humidity sensor may be mounted near the end of the housing and shielded from the heat source within the housing.

The gas delivery device may include a manual reset button that does not require user intervention in the heat patch thermostat, thereby providing over-temperature protection in the event of a malfunction.

Motor control

The motor of the blower is controlled so that the blower can rapidly change the pressure and flow rate of the gas. As shown in fig. 2, the gas delivery device includes a motor and motor controller for the gas delivery device, the motor and motor controller including the following major subsystems:

brushless DC motors comprising one hall effect sensor for rotor position sensing;

a digital motor controller;

motor driver and excess current detection electronics; and

hall effect sensor signal conditioning and analog/digital converter (ADC).

Brushless DC motor

Brushless DC motors known in the art require three hall effect sensors to provide the required rotor position information. The present invention includes a control method that requires only one hall effect position sensor.

The gas delivery device comprises an electric machine comprising three windings, which are designed in a star topology. According to the invention, these windings are energized in a predetermined sinusoidal sequence to start and maintain the rotation of the motor. The duty cycle of this sequence determines how much power is consumed by the motor, which in turn controls the motor speed.

Motor drive electronic circuit

The motor drive subsystem includes the electronics necessary to power the motor windings and sense the motor current. The motor driver comprises six MOSFETs arranged in a three half-bridge driver configuration. These FETs power the motor windings. It also contains the necessary level shifters for converting the LVCMOS signals from the motor controller to the appropriate MOSFET drive signals.

The motor current sensing circuit shown in fig. 3 is used to signal an excess current condition to the motor controller. This allows the controller to shut down the motor in the event of an excessive current fault. According to the invention, this is achieved by a fixed level excess current threshold detector. The present invention includes two parts of the current feedback subsystem. The first part is a simple low pass filter amplifier that amplifies and filters the voltage across the current sense resistor. The second part is a simple comparator with hysteresis for detecting excessive current faults. The output of the comparator is driven directly into the motor controller.

Motor position feedback

According to the invention, the motor has a Hall effect sensor for detecting the position of the rotor. The signal is converted to a digital value by the ADC.

Motor controller

According to the present invention, the motor controller rotates the gas delivery device motor. The controller causes the motor to rotate at an appropriate frequency, depending on the application, e.g., CPAP, APAP, BiPAP or VPAP. It uses a hall effect sensor to receive rotor position feedback, and it uses the hall effect sensor to generate three sinusoidal PWM drive signals.

The motor controller includes the following inputs and outputs:

on/off, input through the microprocessor interface to turn the motor on or off;

motor gain, input through microprocessor interface to set motor speed;

a phase input to set the relative phase between the hall effect position sensor and phase 0 of the drive motor winding 1;

an excess current, the input signaling the occurrence of an excess current and causing the motor controller to stop the motor;

an SPI interface that periodically samples the hall effect position ADC and passes this data to the controller;

phase 0, motor winding 1 drives high and low signals of the electronics;

phase 120, high and low signals of the motor winding 2 driving electronics;

the signal is shifted 120 degrees with respect to phase 0.

Phase 240, high and low signals of the motor winding 3 driving electronics;

the signal is shifted 120 degrees with respect to phase 120.

As an example of the implementation of the present invention, a block diagram of the motor controller shown in FIG. 4 is described herein.

ADC driver

The ADC driver is an SPI interface that samples the hall effect sensor ADC every 2040 clock cycles (5.1 μ s). It outputs the original rotor position as a 12-bit number and generates a sample enable signal with each new sample. This triggers the following subsystems to process the new data. The output of the hall effect sensor, when rotated, is a sine wave when graphically represented. The curve above the ADC driver block in fig. 4 shows the digitized raw hall effect sensor signal obtained for 1 rotor revolution. The "y" axis represents the ADC values (0 to 123). Note that: the minimum value is always greater than 0 and the maximum value is always less than 1023.

Level shift

The rotor position is processed to calculate a period, a maximum value and a minimum value. This subsystem calculates the peak-to-peak amplitude (maximum ADC value-minimum ADC value) of the position sensor raw data samples. This value is recalculated every eight motor cycles. It is level shifted by subtracting the minimum ADC value from the current raw data sample and output to the signal adjusted normalization subsystem. Fig. 4 shows a level shift waveform.

Normalization

This subsystem processes the peak-to-peak amplitude and current signal adjustment samples to normalize the signal so that the position is in the range of 0 to 1023. Fig. 4 shows a normalized waveform. The normalized signal is clipped to 10 bit resolution and fed to the period subsystem where the signal clipped to 10 bit resolution is processed to determine the rotor period. The rotor period is a measure of the system clock per revolution of the rotor. The motor is commutated by a 12 sample digital sine wave oscillator generated in this subsystem. The synchronous rising input signals the rotor to be at a zero crossing position, resetting the sine wave oscillator to position 0. Thus, the phase of the sine wave oscillator is locked to the zero crossing point. According to the invention, the current sine wave oscillator value is increased after every 1/12 cycles of the system clock. If the motor speed exceeds a predetermined level, the current sine wave oscillator value is multiplied by the gain input and then trimmed to 10 bits. The gain input is a 10-bit value controlled by a microprocessor interface including motor speed control. According to the present invention, if the motor speed is less than the predetermined level, the system gain is set to a fixed value to ensure reliable motor starting.

Period detection

The period detection subsystem calculates the rotor period from the system clock for each rotor revolution. The least significant bit and most significant bit (msb) transitions of the normalized signal input represent zero crossing points. The number of system clocks between these transitions is given as the period. To provide a filtered level, the period value is the average of the current and previous period calculations. The phase input allows a user selectable (via a microprocessor interface) phase offset to be added to the system. This is used to optimize the motor performance and to account for sensor position relative to the winding 1. This is an 8-bit value, where a value of 128 represents a phase offset of 180 degrees. The phase 0 delay output contains the number of ADC samples that are delayed to obtain the desired phase offset. The phase 120 delay output contains the number of ADC samples that wait to obtain a phase offset of 120 degrees.

Three phase generation

The drive signals are passed through 3 delay lines to generate 0 °, 120 °, and 240 ° drive signals. The 0 delay line is used to synchronize the zero crossing point with the rotor position. The 120 and 240 delay lines are dynamically adjusted with a period of 1/3 to calculate how much each line should be delayed.

Symmetric PWM generation

The three sine waves are then pulse width modulated. The pulses are arranged symmetrically about a center point. According to the invention this is achieved by using a triangular reference waveform instead of a standard sawtooth reference waveform. Fig. 5 illustrates the operation of the PWM function. Each input sample is modulated by a ramp function to produce a binary output having a logical one pulse width proportional to the amplitude of the 10-bit input sample. Thus, the gain setting in the normalization subsystem has the effect of adjusting the duty cycle of the PWM output. The larger the pulse width, the more power is delivered to the motor and the faster the motor rotates.

Electric H drive

Each PWM signal is converted into 2 complementary drive signals, one for the N-channel FET and the other for the P-channel FET. When switching from an N-FET to a P-FET (and vice versa), a small amount of dead space is inserted to prevent the N-channel and P-channel from conducting simultaneously and shorting the 9V rail. This reduces the power consumption of the FET and also reduces noise generation.

Electronic circuit subsystem

The present invention includes two Printed Circuit Boards (PCBs) arranged as shown in fig. 7.

The CPU box is responsible for:

APAP algorithm

Humidifier controller

Data recording

Visual display

Tone

High level data communication

The memory block includes computer memory.

The LCD frame contains an LCD display, preferably with white LEDs. It is used to provide visual feedback to the user. The RTC utilizes a real time clock chip. It will have a backup power source for data maintenance. In addition to the hold time, the clock is also used to hold status information about the gas delivery device, so that operation can be resumed in the event of a power failure. The EEPROM stores the calibration data of the cell. These devices all communicate with the CPU block.

The debug/RS 232 box contains the necessary ethernet or RS232 interface connectors/logic for diagnostic and control purposes.

The keyboard frame includes four LED backlit buttons that control the unit. The buttons are arranged in a row. One button can be used as both an on/off switch and a mode selection button. The other buttons are option selection buttons.

The FPGA frame includes the following functions:

motor controller

CPU interface for sensor signals (flow, pressure, ambient temperature, sheet temperature and humidity)

CPU interface for SD card

CPU interface for Ethernet controller

CPU interface and controller for buzzer frame

The buzzer bezel is used to provide audible feedback for button presses and alarms.

The sensor ADC includes analog-to-digital conversion for the flow, pressure and chip temperature sensor signals. The pressure sensor measures the pressure of the generated air flow. Differential pressure techniques are used to measure the flow rate of an air stream. It includes sheet temperature feedback for the humidifier controller. The power supply takes a DC input and generates four voltages. The heater block includes a switching mechanism and isolation for controlling the humidifying heat patch. The SD card box includes the necessary logic for the SD card holder and for interfacing the FPGA box to the SD card. The RS232 or ethernet box contains the connectors for serial or LAN connections.

For the present invention, the FPGA controls the operation of the motor. The CPU interface allows the microprocessor to control the FPGA. The decoder is a separate block that performs chip selection for the interface. The sensor ADC interface performs serial-to-parallel conversion. The interface reads the channel and stores the result in a register accessible through the CPU interface. The temperature interface performs a serial-to-parallel conversion on the temperature sensor. The temperature is stored in a register accessible through the CPU interface. The humidity interface performs periodic measurements of the humidity signal from the main PCB of the gas delivery device. The result is accessible through the CPU interface. The buzzer controller generates a square wave signal for driving a buzzer, preferably a piezoelectric buzzer. The frequency and duty cycle may be programmed through the CPU interface.

The card controller includes a read-write buffer for accessing a card on the gas delivery device. It is designed to ease processing from the processor.

Description of software/firmware

The present invention includes firmware that is a pre-emissive multi-tasking system.

The main parts of the gas delivery device firmware include:

core

Trouble task

Automatic CPAP Algorithm

Task of humidifier

SD card task

Command task

Communication tasks

Display tasks

Monitoring tasks

FPGA download function

Firmware upgrade function

Real time clock function

·E^EPROM function

The kernel is under the OS for coordinating switching between tasks and handling low level tasks such as interrupt handling and QSPI access. The failed task is the highest priority task. It is used to monitor the motor for a fault condition and then take appropriate action to shut down and report the fault. The humidification task is used to control the humidification heater. It controls how much power is supplied to the heater to generate a certain degree of humidity based on the current ambient temperature and humidity. The SD card task records data generated by the algorithm, the malfunction, and the humidification task in the SD card. This command task is the basic monitor program for enabling control of the invention through the serial port or 10/100 ethernet port. The communication task controls either the serial port or the ethernet port 10/100. The display task controls the LCD and the buzzer. It also provides the alarm/clock function of the unit. The remaining four sections include sets of utility functions that provide access to the various sections of the gas delivery device. These functions include FPGA download, real time clock interface, E^EPROM access and FLASH/firmware reprogramming.

Table 1 acronyms used in this document

CPU	Central processing unit
		E2PROM	Electrically erasable programmable read only memory
EMI	Electromagnetic interference
		FET	Field effect transistor
FPGA	Field programmable gate array
		LCD	Liquid crystal display device with a light guide plate
LED	Light emitting diode
		LVCMOS	Low voltage CMOS
MOSFET	Metal oxide semiconductor field effect transistor
		PWM	Pulse width modulation
RTC	Real-time clock
		SPI	Serial peripheral interface

Claims (18)

1. An apparatus for delivering breathable gas to a subject, the apparatus comprising:

a blower for delivering compressed gas;

a reservoir for humidifying the gas;

a water heater;

a housing for housing the blower and the reservoir;

an air inlet and an air outlet, both of which are coupled to a port in the reservoir; and

a conduit for guiding the gas from the gas outlet to a subject.

2. An apparatus for delivering breathable gas to a subject, the apparatus comprising:

a gas filter housed in the movable transparent case and filtering the gas;

a blower for sucking filtered gas and delivering compressed gas, said blower being disposed within the sound-proof housing;

a housing for housing the blower and a reservoir;

the heater is used for heating the water in the water storage tank;

an air inlet and an air outlet, both of which are coupled to a port in the reservoir; and

a conduit for guiding the gas from the gas outlet to a subject.

3. An apparatus for delivering breathable gas to a subject, the apparatus comprising:

a blower for delivering compressed gas;

a housing for accommodating the blower;

an air inlet and an air outlet, both of which are coupled to a port in the reservoir;

a conduit for guiding gas from the gas outlet to a subject; and

at least one plenum and at least one resonating device adjacent to the blower.

4. The apparatus of claim 3, further comprising a reservoir and a heater to heat water in the reservoir.

5. The apparatus of any one of claims 1 to 4, wherein the conduit comprises concentric conduits for gas inflow and gas outflow.

6. The apparatus of claim 5, wherein the gas inflow conduit comprises an internal conduit.

7. The apparatus of any one of claims 1 to 4, wherein the apparatus can be set for operation at any suitable angle from substantially horizontal to substantially vertical without leakage of liquid from the reservoir.

8. An apparatus for delivering breathable gas to a subject, the apparatus comprising:

a blower for delivering compressed gas;

a reservoir for humidifying the gas;

a water heater;

a housing for housing the blower and the reservoir;

an air inlet and an air outlet, both of which are coupled to a port in the reservoir; and

a duct for guiding the gas from the gas outlet to a subject,

wherein the apparatus may be set for operation at any suitable angle from a substantially horizontal orientation to a substantially vertical orientation without leakage of liquid from the reservoir.

9. The apparatus of any one of claims 1, 2, 4, 6 and 8, wherein the air inlet and outlet are engaged with an aperture in the water reservoir.

10. The apparatus of claim 8, wherein the conduit comprises concentric conduits for gas inflow and gas outflow.

11. The apparatus of claim 10, wherein the gas inflow tube comprises an internal conduit.

12. The apparatus of claim 8, wherein the apparatus can be set for operation at any suitable angle from substantially horizontal to substantially vertical without leaking liquid from the reservoir.

13. The apparatus of any one of claims 1, 3, 4, 6, 8, 10, 11 and 12, further comprising a gas filter contained within the movable transparent housing.

14. The apparatus of any one of claims 1, 3, 4, 6, 8, 10, 11 and 12, further comprising a lid in sealing engagement with the water reservoir.

15. An apparatus for delivering breathable gas to a subject, the apparatus comprising:

a blower having an outlet for delivering compressed gas, the blower including a motor chamber, two outlet gas passages, and a valve chamber, the blower including means for rapidly changing the pressure or flow rate of the gas;

a housing for housing the blower and a reservoir;

an air inlet and an air outlet, both of which are coupled to a port in the reservoir;

a gas filter housed within the movable transparent housing; and

a conduit for guiding the gas from the gas outlet to a subject.

16. The apparatus of claim 15, wherein the means for varying the pressure or flow rate of the gas is at least one impeller.

17. The apparatus according to any one of claims 1, 3, 4, 6, 8, 10, 11, 12, 15 and 16, further comprising time signaling means.

18. A method of delivering breathable gas to a subject, the method comprising the steps of:

compressing the ambient gas with an impeller;

humidifying the ambient gas;

directing the humidified gas to an airway of a subject; and

wherein the compressing step comprises detecting the position of the impeller with one sensor device, wherein the one sensor device is a hall effect sensor, the rotation of the impeller is driven by a motor, and the electrical commutation is phased by the hall effect sensor being positioned adjacent to the rotor magnet.