Patent Publication Number: US-2023144814-A1

Title: Breathing assistance apparatus

Description:
TECHNICAL FIELD 
     The present disclosure relates to a flow therapy apparatus for delivering gas to patients. 
     BACKGROUND ART 
     Breathing assistance apparatuses are used in various environments such as hospital, medical facility, residential care, or home environments to deliver a flow of gas to users or patients. 
     SUMMARY 
     The applicant has identified potential difficulties in inserting and/or retaining and/or removing a cover of a breathing assistance apparatus, particularly for users with limited mobility. 
     The applicant has also identified potential difficulties in inserting and/or retaining and/or removing a liquid chamber in and/or from a liquid chamber bay of a breathing assistance apparatus, particularly for users with limited mobility. Full or correct insertion and/or retention may be required to ensure that a satisfactory seal is obtained and maintained between the liquid chamber and other component(s) that form part of the gasflow path. 
     The applicant has further identified potential strength limitations in handles that are movably connected to breathing assistance apparatus housings. 
     It would be desirable to provide a cover for an apparatus for delivering a flow of gas that has one or more features that assist with cleaning the cover and/or apparatus. 
     It would be desirable to provide an apparatus for delivering a flow of gas that has one or more features that assist with inserting and/or retaining and/or removing a cover from a breathing assistance apparatus. 
     It would be desirable to provide an apparatus for delivering a flow of gas that has one or more features that assist with inserting and/or retaining and/or removing a liquid chamber in and/or from a liquid chamber bay. 
     It would be desirable to provide an apparatus for delivering a flow of gas that has a movable handle that can better accommodate loadings that are encountered when the handle is used to carry the apparatus. 
     It is an object of one or more of the disclosed embodiments to provide an apparatus for delivering a flow of gas that has one or more features that assist with the use, functioning, or configuration of the apparatus or improves the safety of the apparatus, or that will at least provide the public or a medical professional with a useful choice. 
     Thus, in accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, an apparatus for delivering a flow of gas, comprises: a housing and a cover, a magnetic coupling system arranged to magnetically couple the cover to the housing, each of the housing and cover having complementary locating features, the locating features being adapted to locate and align the cover and the housing relative to each other to allow for said magnetic coupling. 
     In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, there is provided a cover for an apparatus for delivering a flow of gas, the cover comprising locating features for engaging with complementary locating features of the apparatus the locating features being adapted to locate and align the cover and the apparatus relative to each other to allow for magnetic coupling between the cover and the apparatus. 
     In some embodiments the magnetic coupling system comprises at least one magnet associated with one of the housing or cover and at least one ferrous part associated with the other of the housing or cover. 
     In some embodiments the magnetic coupling system comprises multiple magnets associated with one of the housing or cover. 
     In some embodiments the magnetic coupling system comprises multiple ferrous parts associated with the other of the housing or cover. 
     In some embodiments the magnetic coupling system comprises at least one magnet associated with the housing and at least one other magnet associated with the cover. 
     In some embodiments the magnetic coupling system comprises multiple magnets associated with the housing and multiple magnets associated with the cover. 
     In some embodiments the at least one magnet is attached by interference fit and/or adhesive. 
     In some embodiments the cover or apparatus has at least one upstand to hold the at least one magnet. 
     In some embodiments the apparatus comprises multiple magnets associated with at least one of the cover and the housing, and wherein at least one magnet associated with the cover and at least one magnet associated with the housing are arranged such that they attract when the cover is coupled to the housing in a predetermined orientation of the cover relative to the housing and repel when the cover is offered to the housing in at least one orientation other than said predetermined orientation. 
     In some embodiments the at least one magnet is embedded in the cover or housing. 
     In some embodiments the at least one magnet is covered by a surface of the cover or housing. 
     In some embodiments the locating features of the housing and the cover are interlocking features adapted to form an interlock. 
     In some embodiments the locating feature of one of the cover or housing comprises at least one projection and the locating feature of the other of the cover or housing comprises at least one recess, the projection and recess forming the interlock. 
     In some embodiments the at least one projection comprises angled rear and front faces and the at least one recess comprises complementary angled rear and front faces. 
     In some embodiments the rear face of the projection is of a shorter length than the length of the front face of the projection. 
     In some embodiments the front face of the projection is of a shorter length than the length of the rear face of the projection. 
     In some embodiments the locating features are adapted to prevent relative movement between the cover and the housing. 
     In some embodiments the locating features comprise side walls, and optionally back walls, of the cover. 
     In some embodiments the locating features comprise the lower surface of the side walls. 
     In some embodiments, the locating features comprise the lower surface of the side walls. 
     In some embodiments the interlocking features are adapted to prevent relative movement between the cover and the housing, optionally the interlocking features prevent relative movement between the cover and the housing in an axis substantially parallel with the side wall of the cover. 
     In some embodiments the interlocking features prevent relative movement between the cover and the housing in an axis substantially parallel to a direction in which the removable elbow is removed. 
     In some embodiments the cover has a back wall. In some embodiments the cover has a front wall. The back wall and/or front wall may be recessed from an edge of the cover. 
     In some embodiments the cover covers, retains, assists with retention and/or positions a component of the apparatus. 
     In some embodiments the component is a removable component. 
     In some embodiments the component is part of a flow path, for example, a removable elbow. 
     In some embodiments the component has a pneumatic and/or an electrical connection. 
     In some embodiments the cover has an aperture to allow for passage of component. 
     In some embodiments the cover has a lead-in feature to engage part of the component upon initial engagement, to ensure correct alignment between the cover, the breathing apparatus, and the component. 
     In some embodiments the lead-in feature engages with one or more of the pneumatic or electrical connection features of the removable elbow. 
     In some embodiments the locating features associated with the housing and the cover allow the cover and housing to be assembled together in a predetermined orientation of the cover relative to the housing and prevent the cover and housing being assembled together when the cover is offered to the housing in at least one orientation other than said predetermined orientation. 
     In some embodiments the side walls of the cover are asymmetrical about a transverse axis. 
     In some embodiments the cover comprises an aperture extending through the top of the cover. 
     In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, there is provided an apparatus for delivering a flow of gas, comprising: a housing and a cover, a magnetic coupling system arranged to magnetically couple the cover to the housing. 
     In some embodiments the magnetic coupling system comprises at least one magnet, optionally multiple magnets, associated with one of the housing or cover and at least one ferrous part, optionally multiple ferrous parts, associated with the other of the housing or cover. 
     In some embodiments the magnetic coupling system comprises at least one magnet, optionally multiple magnets, associated with the housing and at least one other magnet, optionally multiple magnets, associated with the cover. 
     In some embodiments the at least one magnet is attached by interference fit and/or adhesive. 
     In some embodiments the cover or apparatus has at least one upstand to hold the at least one magnet. 
     In some embodiments the apparatus comprises multiple magnets associated with at least one of the cover and the housing, and wherein at least one magnet associated with cover and at least one magnet associated with the housing are arranged such that they attract when the cover is coupled to the housing in a predetermined orientation of the cover relative to the housing and repel when the cover is offered to the housing in at least one orientation other than said predetermined orientation. 
     In some embodiments the at least one magnet is embedded in the cover or housing and optionally covered by a surface of the cover or housing. 
     In some embodiments the cover covers, retains, assists with retention and/or positions a component, optionally a removable component, of the apparatus. 
     In some embodiments the component is part of a flow path. 
     In some embodiments the cover has an aperture to allow for passage of the component. 
     In some embodiments the cover has a lead-in feature to engage part of the component upon initial engagement, to ensure correct alignment between the cover, the breathing apparatus, and the component. 
     In some embodiments the lead-in feature engages with one or more of the pneumatic or electrical connection features of the removable elbow. 
     In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, there is provided an apparatus for delivering a flow of gas, comprising: a housing and a cover, each of the housing and cover having complementary locating features, the locating features being adapted to locate and align the cover and the housing relative to each other. 
     In some embodiments the locating features of the housing and the cover are interlocking features adapted to form an interlock. 
     In some embodiments the locating feature of one of the cover or housing comprises at least one projection and the locating feature of the other of the cover or housing comprises at least one recess, the projection and recess forming the interlock. 
     In some embodiments the at least one projection comprises angled rear and front faces and the at least one recess comprises complementary angled rear and front faces. 
     In some embodiments the rear face of the projection is of a shorter length than the length of the front face of the projection or the front face of the projection is of a shorter length than the length of the rear face of the projection. 
     In some embodiments the locating features comprise side walls, and optionally back walls, of the cover. 
     In some embodiments the interlocking features are adapted to prevent relative movement between the cover and the housing, optionally the interlocking features prevent relative movement between the cover and the housing in an axis substantially parallel with the side wall of the cover. 
     In some embodiments the interlocking features prevent relative movement between the cover and the housing in an axis substantially parallel to a direction in which the elbow is removed. 
     In some embodiments the cover covers, retains, assists with retention and/or positions a component, optionally a removable component, of the apparatus. 
     In some embodiments the component is part of a flow path. 
     In some embodiments the cover has an aperture to allow for passage of the component. 
     In some embodiments the cover has a lead-in feature to engage part of the component upon initial engagement, to ensure correct alignment between the cover, the breathing apparatus, and the component. 
     In some embodiments the lead-in feature engages with one or more of the pneumatic or electrical connection features of the removable elbow. 
     In some embodiments the locating features associated with the housing and the cover allow the cover and housing to be assembled together in a predetermined orientation of the cover relative to the housing and prevent the cover and housing being assembled together when the cover is offered to the housing in at least one orientation other than said predetermined orientation. 
     In some embodiments the side walls of the cover are asymmetrical about a transverse axis. 
     In some embodiments the cover comprises an aperture extending through the top of the cover. 
     In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, there is provided an apparatus for delivering a flow of gas, comprising: a housing, a component of the apparatus, and a cover that assists with retaining of the component, a component coupling that substantially inhibits the component from moving relative to the housing in a first direction, and a cover coupling that substantially inhibits the cover from moving relative to the housing in a second direction. 
     In some embodiments the cover coupling is or comprises a magnetic coupling. 
     In some embodiments the cover coupling is or comprises each of the housing and cover having complementary locating features. 
     In some embodiments the locating features of the housing and the cover are interlocking features adapted to form an interlock. 
     In some embodiments the first and second direction are substantially perpendicular. 
     In some embodiments the second direction is substantially horizontal. 
     In some embodiments the first direction is substantially vertical. 
     In accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, an apparatus for delivering a flow of gas is disclosed, the apparatus comprising: a housing and a handle, wherein the handle is movably connected to the housing and is movable from a first position to a second position, wherein the housing and the handle comprise complementary interlock features, and wherein the complementary interlock features are arranged such that the interlock features engage with each other when the handle is in the second position and upward force is applied to the handle relative to the housing, and such that the interlock features are disengaged from each other when the handle is in the second position but upward force is not applied to the handle relative to the housing. 
     In some configurations, the first position is a lowered position and the second position is a raised position. In alternative configurations, the first and/or second position are different position(s). For example, one or both of the first and second positions could be an intermediate position between the lowered position and the raised position. 
     In some configurations, the interlock features are disengaged from each other when the handle is in an intermediate position between the lowered position and the raised position. In some configurations, the interlock features are disengaged from each other when the handle is in any of a plurality of intermediate positions between the lowered position and the raised position. 
     In some configurations, the interlock features are engaged with each other when the handle is in an intermediate position between the lowered position and the raised position. 
     In some configurations, the interlock features comprise a projection on one of the handle and the housing, and a complementary recess on the other of the handle and the housing. In some configurations, at least one of the projection and the recess comprise an angled face to assist with engagement and/or disengagement of the projection and the recess. In some configurations, the angled face(s) comprise forward face(s) of the projection and/or the recess. 
     In some configurations, the interlock features comprise a plurality of projections on one of the handle and the housing, and a plurality of complementary recesses on the other of the handle and the housing. 
     In some configurations, the handle comprises an additional interlock feature that is arranged to engage with the interlock feature of the housing when the handle is in the first position. In some configurations, the additional interlock feature has the same form as one of the interlock features on the handle. 
     In some configurations, the apparatus comprises a heater and a liquid chamber bay for receipt of a liquid chamber. In some configurations, the handle encloses a portion of the liquid chamber bay when the handle is in the first position. 
     In some configurations, liquid tube(s) can be fed through a space between the handle and the housing when the handle is in the second position. 
     In some configurations, the handle is pivotally connected to the housing. In some configurations, only one side of the handle is pivotally connected to the housing. In some alternative configurations, two sides of the handle are pivotally connected to the housing. 
     In some configurations, the handle is pivotally and translationally connected to the housing. In some configurations, only one side of the handle is pivotally and translationally connected to the housing. In some alternative configurations, two sides of the handle are pivotally and translationally connected to the housing. 
     In some configurations, the apparatus comprises a handle retainer that is fixed to part of the housing, wherein the handle retainer and part of the housing together provide pivoting and translational movement of the handle relative to the housing. 
     In some configurations, the handle is configured to move relative to the housing with a varying radius of movement. 
     In some configurations, the handle comprises a first pivot that is configured to move along a first pivot cavity, and the handle comprises a second pivot that is configured to move along a second pivot cavity. In some configurations, the first pivot cavity is generally 3-shaped. 
     In some configurations, a portion of the first pivot cavity is arranged to enable upward movement of the first pivot when the handle is in the second position and the handle is used to lift the apparatus. 
     In some configurations, the second pivot cavity is oriented in a substantially forward-rearward direction of the apparatus. 
     In some configurations, the second pivot cavity is arcuate. 
     In some configurations, a portion of the second pivot cavity is arranged to enable upward movement of the second pivot when the handle is in the second position and the handle is used to lift the apparatus. 
     In some configurations, the handle comprises a body, a first pivot protrusion extending from the body, and a second pivot protrusion extending from the body, wherein the first and second pivot protrusions each have an exposed axial length and a transverse dimension, wherein the transverse dimension is greater than the axial length. In some configurations, the transverse dimension is at least twice the axial length. 
     In some configurations, the handle comprises an arm on said one side of the handle, wherein the arm is pivotally, or pivotally and translationally, connected to the housing. In some configurations, the handle comprises a cross-member that is connected to the arm. 
     In some configurations, there is a space between the housing and the cross-member on a side of the handle opposite to the arm, when the handle is in the second position. 
     In some configurations, a terminal end of the handle is arranged to be positioned generally above a centre of mass of the apparatus, when the handle is in the second position. 
     In some configurations, the handle and/or housing comprise one or more magnets to retain the handle in the lowered position. 
     Additionally, in accordance with certain features, aspects and advantages of at least one of the embodiments disclosed herein, an apparatus for delivering a flow of gas is disclosed, the apparatus comprising: a housing and a handle, wherein the handle is movably connected to the housing and is movable from a first position to a second position, wherein the housing and the handle comprise complementary interlock features, and wherein the complementary interlock features are arranged such that the interlock features engage with each other when the handle is in the second position and upward force is applied to the handle relative to the housing, and such that the interlock features engage with each other when the handle is in the first position. 
     In some configurations, the first position is a lowered position and the second position is a raised position. In alternative configurations, the first and/or second position are different position(s). For example, one or both of the first and second positions could be an intermediate position between the lowered position and the raised position. 
     In some configurations, the interlock features are disengaged from each other when the handle is in an intermediate position between the lowered position and the raised position. In some configurations, the interlock features are disengaged from each other when the handle is in any of a plurality of intermediate positions between the lowered position and the raised position. 
     In some configurations, the interlock features are disengaged from each other when the handle is in an intermediate position between the lowered position and the raised position. In some configurations, the interlock features are disengaged from each other when the handle is in any of a plurality of intermediate positions between the lowered position and the raised position. 
     In some configurations, the interlock features comprise a plurality of projections on one of the handle and the housing, and a plurality of complementary recesses on the other of the handle and the housing. In some configurations, at least one of the projections and the recesses comprise an angled face to assist with engagement of the projection(s) and the recess(es). In some configurations, the angled face(s) comprise forward face(s) of the projection(s) and/or the recess(es). 
     In some configurations, the apparatus comprises a heater and a liquid chamber bay for receipt of a liquid chamber. In some configurations, the handle encloses a portion of the liquid chamber bay when the handle is in the first position. 
     In some configurations, the handle is pivotally connected to the housing. In some configurations, only one side of the handle is pivotally connected to the housing. In some alternative configurations, two sides of the handle are pivotally connected to the housing. 
     In some configurations, the handle is pivotally and translationally connected to the housing. In some configurations, only one side of the handle is pivotally and translationally connected to the housing. In some alternative configurations, two sides of the handle are pivotally and translationally connected to the housing. 
     In some configurations, the apparatus comprises a handle retainer that is fixed to part of the housing, wherein the handle retainer and part of the housing together provide pivoting and translational movement of the handle relative to the housing. 
     In some configurations, the handle is configured to move relative to the housing with a varying radius of movement. 
     In some configurations, the handle comprises a first pivot that is configured to move along a first pivot cavity, and the handle comprises a second pivot that is configured to move along a second pivot cavity. In some configurations, the first pivot cavity is generally 3-shaped. 
     In some configurations, a portion of the first pivot cavity is arranged to enable upward movement of the first pivot when the handle is in the second position and the handle is used to lift the apparatus. 
     In some configurations, the second pivot cavity is oriented in a substantially forward-rearward direction of the apparatus. 
     In some configurations, the second pivot cavity is arcuate. 
     In some configurations, a portion of the second pivot cavity is arranged to enable upward movement of the second pivot when the handle is in the second position and the handle is used to lift the apparatus. 
     In some configurations, the handle comprises a body, a first pivot protrusion extending from the body, and a second pivot protrusion extending from the body, wherein the first and second pivot protrusions each have an exposed axial length and a transverse dimension, wherein the transverse dimension is greater than the axial length. In some configurations, the transverse dimension is at least twice the axial length. 
     In some configurations, the handle comprises an arm on said one side of the handle, wherein the arm is pivotally, or pivotally and translationally, connected to the housing. In some configurations, the handle comprises a cross-member that is connected to the arm. 
     In some configurations, there is a space between the housing and the cross-member on a side of the handle opposite to the arm, when the handle is in the second position. 
     In some configurations, a terminal end of the handle is arranged to be positioned generally above a centre of mass of the apparatus, when the handle is in the second position. 
     In some configurations, the handle and/or housing comprise one or more magnets to retain the handle in the first position. 
     It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1.5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner. 
     Features from one or more embodiments may be combined with features of one or more other embodiments. Additionally, more than one embodiment may be used together during a process of respiratory support of a patient. 
     The term “comprising” as used in this specification means “consisting at least in part of”. When interpreting each statement in this specification that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner. 
     It should be understood that alternative embodiments may comprise any or all combinations of two or more of the parts, elements or features illustrated, described or referred to in this specification. 
     This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features. 
     To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Specific embodiments and modifications thereof will become apparent to those skilled in the art from the detailed description herein having reference to the figures that follow, of which: 
         FIG.  1    shows in diagrammatic form a breathing assistance apparatus in the form of a flow therapy apparatus. 
         FIG.  2    is a front, right side overhead perspective view of the flow therapy apparatus with a humidifier chamber in position and a lowered handle/lever. 
         FIG.  3    shows the apparatus with the liquid chamber removed from the liquid chamber bay. 
         FIG.  4    is a top view of the apparatus with the cover removed. 
         FIG.  5    is a perspective view of one embodiment of the cover. 
         FIG.  6    is a perspective view of the cover of  FIG.  5    and one embodiment of a screen carrier assembled together. 
         FIG.  7    is a perspective view from below of the cover of  FIG.  5   . 
         FIG.  8    is a perspective view from below of the screen carrier of  FIG.  6   . 
         FIG.  9    is a perspective view from above of the screen carrier of  FIG.  6   . 
         FIG.  10    is a perspective view of an optional tether. 
         FIG.  11    shows a removable elbow. 
         FIG.  12    is a perspective view from above of another embodiment of the cover. 
         FIG.  13    is a perspective view from below of the cover of  FIG.  12   . 
         FIG.  14    is a perspective view from above of another embodiment of the screen carrier. 
         FIG.  15    is a perspective view from below of the screen carrier of  FIG.  14   . 
         FIG.  16    is a perspective view of the cover of  FIG.  12    and the screen carrier of  FIG.  14    assembled together. 
         FIG.  17    is another perspective view of the cover of  FIG.  12    and the screen carrier of  FIG.  14    assembled together. 
         FIG.  18    is a perspective view from below of another embodiment of the cover. 
         FIG.  19    is a perspective view from above of another embodiment of the screen carrier. 
         FIG.  20    is a perspective view of the cover of  FIG.  18    and the screen carrier of  FIG.  19    assembled together. 
         FIG.  21    is a perspective view of a battery cover. 
         FIG.  22    is a bottom view of the battery cover of  FIG.  21   . 
         FIG.  23    is a partial side view of the battery cover of  FIG.  21   . 
         FIG.  24    is a perspective view from below of a housing. 
         FIG.  25    is another perspective view of the battery cover. 
         FIG.  26    is a side view of the battery cover of  FIG.  21   . 
         FIG.  27    is a view corresponding to  FIG.  2   , but with the handle/lever in a partly raised position. 
         FIG.  28    is a view corresponding to  FIG.  27   , but with the handle/lever in a more raised position. 
         FIG.  29    is a view corresponding to  FIG.  28    but with the handle/lever in a fully raised position. 
         FIG.  30    is a left side partial section view showing part of the apparatus housing, the handle retainer, and the handle/lever in the lowered position corresponding to  FIG.  2   . 
         FIG.  31    is a view corresponding to  FIG.  30    but with the handle/lever in the partly raised position corresponding to  FIG.  27   . 
         FIG.  32    is a view corresponding to  FIG.  30    but with the handle/lever in the more raised position corresponding to  FIG.  28   . 
         FIG.  33    is a view corresponding to  FIG.  30    but with the handle/lever in the fully raised position corresponding to  FIG.  29   . 
         FIG.  34    is a front left perspective view of the handle retainer and the handle/lever in the lowered position corresponding to  FIG.  2   . 
         FIG.  35    is a view corresponding to  FIG.  34    but with the handle/lever in the partly raised position corresponding to  FIG.  27   . 
         FIG.  36    is a view corresponding to  FIG.  34    but with the handle/lever in the more raised position corresponding to  FIG.  28   . 
         FIG.  37    is a view corresponding to  FIG.  34    but with the handle/lever in the fully raised position corresponding to  FIG.  29   . 
         FIG.  38    is a front right perspective view of the handle retainer and the handle/lever in the lowered position corresponding to  FIG.  2   . 
         FIG.  39    is a view corresponding to  FIG.  34    but with the handle/lever in the partly raised position corresponding to  FIG.  27   . 
         FIG.  40    is a view corresponding to  FIG.  34    but with the handle/lever in the more raised position corresponding to  FIG.  28   . 
         FIG.  41    is a view corresponding to  FIG.  34    but with the handle/lever in the fully raised position corresponding to  FIG.  29   . 
         FIG.  42    is a front left overhead perspective view of the apparatus with the upper chassis part removed. 
         FIG.  43    is a rear left underside perspective view of the upper chassis of the apparatus. 
         FIG.  44    is a rear right side perspective view of the handle/lever. 
         FIG.  45    is a front left side perspective view of the handle/lever. 
         FIG.  46    is a plot showing the movement path of a terminal end of the handle/lever of the apparatus. 
         FIG.  47    is a front left side overhead perspective view showing engagement points between the lowered handle/lever and the liquid chamber. 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     A flow therapy apparatus  10  is shown in  FIG.  1   . In general terms, the apparatus  10  comprises a main housing  100  that contains a flow generator  11  in the form of a motor/impeller arrangement, an optional humidifier  12 , a controller  13 , and a user I/O interface  14  (comprising, for example, a display and input device(s) such as button(s), a touch screen, or the like). The controller  13  is configured or programmed to control the components of the apparatus, including: operating the flow generator  11  to create a flow of gas (gasflow) for delivery to a patient, operating the humidifier  12  (if present) to humidify and/or heat the generated gasflow, receive user input from the user interface  14  for reconfiguration and/or user-defined operation of the apparatus  10 , and output information (for example on the display) to the user. The user could be a patient, healthcare professional, or anyone else interested in using the apparatus. 
     A patient breathing conduit  16  is coupled to a gasflow output  344  in the housing  100  of the flow therapy apparatus  10 , and is coupled to a patient interface  17  such as a nasal cannula with a manifold  19  and nasal prongs  18 . Additionally, or alternatively, the patient breathing conduit  16  could be coupled to a face mask. Additionally or alternatively, the patient breathing conduit could be coupled to a nasal pillows mask, and/or a nasal mask, and/or a tracheostomy interface, or any other suitable type of patient interface. The gasflow, which may be humidified, that is generated by the flow therapy apparatus  10  is delivered to the patient via the patient breathing conduit  16  through the cannula  17 . The patient breathing conduit  16  can have a heater wire  16   a  to heat gasflow passing through to the patient. The heater wire  16   a  is under the control of the controller  13 . The patient breathing conduit  16  and/or patient interface  17  can be considered part of the flow therapy apparatus  10 , or alternatively peripheral to it. The flow therapy apparatus  10 , breathing conduit  16 , and patient interface  17  together form a flow therapy system. 
     General operation of a flow therapy breathing apparatus  10  will be known to those skilled in the art, and need not be described in detail here. However, in general terms the controller  13  controls the flow generator  11  to generate a gasflow of the desired flow rate, controls one or more valves to control the mix of air and oxygen or other alternative gas, and controls the humidifier  12  if present to humidify the gasflow and/or heat the gasflow to an appropriate level. The gasflow is directed out through the patient breathing conduit  16  and cannula  17  to the patient. The controller  13  can also control a heating element in the humidifier  12  and/or the heating element  16   a  in the patient breathing conduit  16  to heat the gas to a desired temperature that achieves a desired level of therapy and/or comfort for the patient. The controller  13  can be programmed with or can determine a suitable target temperature of the gasflow. 
     Operation sensors  3   a ,  3   b ,  3   c ,  20 ,  25  such as flow, temperature, humidity, and/or pressure sensors can be placed in various locations in the flow therapy apparatus  10  and/or the patient breathing conduit  16  and/or cannula  17 . Output from the sensors can be received by the controller  13 , to assist it to operate the flow therapy apparatus  10  in a manner that provides optimal therapy. In some configurations, providing optimal therapy includes meeting a patient&#39;s inspiratory demand. The apparatus  10  may have a transmitter and/or receiver  15  to enable the controller  13  to receive signals  8  from the sensors and/or to control the various components of the flow therapy apparatus  10 , including but not limited to the flow generator  11 , humidifier  12 , and heater wire  16   a , or accessories or peripherals associated with the flow therapy apparatus  10 . Additionally, or alternatively, the transmitter and/or receiver  15  may deliver data to a remote server or enable remote control of the apparatus  10 . 
     The flow therapy apparatus  10  may comprise a high flow therapy apparatus. As used herein, “high flow” therapy refers to administration of gas to the airways of a patient at a relatively high flow rate that meets or exceeds the peak inspiratory demand of the patient. The flow rates used to achieve “high flow” may be any of the flow rates listed below. The flow therapy apparatus  10  may be any suitable type of apparatus, but in some configurations may deliver a high gas flow or high flow therapy (of e.g. air, oxygen, other gas mixture, or some combination thereof) to a patient to assist with breathing and/or treat breathing disorders. In some configurations, the gas is or comprises oxygen. In some configurations, the gas comprises a blend of oxygen and ambient air. ‘High flow therapy’ as used in this disclosure may refer to delivery of gases to an adult patient at a flow rate of greater than or equal to about 10 liters per minute (10 LPM), or to a neonatal, infant, or child patient at a flow rate of greater than or equal to about 1 liters per minute (1 LPM). In some configurations, for an adult patient ‘high flow therapy’ may refer to the delivery of gases to a patient at a flow rate of greater than or equal to about 10 litres per minute (10 LPM), such as between about 10 LPM and about 100 LPM, or between about 15 LPM and about 95 LPM, or between about 20 LPM and about 90 LPM, or between about 25 LPM and about 85 LPM, or between about 30 LPM and about 80 LPM, or between about 35 LPM and about 75 LPM, or between about 40 LPM and about 70 LPM, or between about 45 LPM and about 65 LPM, or between about 50 LPM and about 60 LPM. In some configurations, for a neonatal, infant, or child patient ‘high flow therapy’ may refer to the delivery of gases to a patient at a flow rate of between about 1 LPM and about 25 LPM, or between about 2 LPM and about 25 LPM, or between about 2 LPM and about 5 LPM, or between about 5 LPM and about 25 LPM, or between about 5 LPM and about 10 LPM, or between about 10 LPM and about 25 LPM, or between about 10 LPM and about 20 LPM, or between about 10 LPM and 15 LPM, or between about 20 LPM and about 25 LPM. Therefore, a high flow therapy apparatus for use with either an adult patient or a neonatal, infant, or child patient, may deliver gases to the patient at a flow rate of between about 1 LPM and about 100 LPM, or at a flow rate in any of the sub-ranges outlined above. Gases delivered may comprise a percentage of oxygen. In some configurations, the percentage of oxygen in the gases delivered may be between about 20% and about 100%, or between about 30% and about 100%, or between about 40% and about 100%, or between about 50% and about 100%, or between about 60% and about 100%, or between about 70% and about 100%, or between about 80% and about 100%, or between about 90% and about 100%, or about 100%, or 100%. High flow therapy has been found effective in meeting or exceeding the patient&#39;s inspiratory demand, increasing oxygenation of the patient and/or reducing the work of breathing. Additionally, high flow therapy may generate a flushing effect in the nasopharynx such that the anatomical dead space of the upper airways is flushed by the high incoming gas flows. This creates a reservoir of fresh gas available of each and every breath, while minimising re-breathing of carbon dioxide, nitrogen, etc. 
     The patient interface may be a non-sealing interface to prevent barotrauma (e.g. tissue damage to the lungs or other organs of the respiratory system due to difference in pressure relative to the atmosphere). The patient interface may be a nasal cannula with a manifold and nasal prongs, and/or a face mask, and/or a nasal pillows mask, and/or a nasal mask, and/or a tracheostomy interface, or any other suitable type of patient interface. 
     As shown in  FIGS.  2  to  48    and described below, the flow therapy apparatus  10  has various features to assist with the functioning, use, and/or configuration of the apparatus  10 . 
     As shown in  FIGS.  2  to  4 , and  27  to  30   , the flow therapy apparatus  10  comprises a main housing  100 . The main housing  100  has a main housing upper chassis  102  and a main housing lower chassis  202 . 
     The main housing upper chassis  102  has a peripheral wall arrangement  106 . The peripheral-wall arrangement  106  defines a humidifier or liquid chamber bay  108  for receipt of a removable liquid chamber  300 . The removable liquid chamber  300  contains a suitable liquid such as water for humidifying gases that will be delivered to a patient. 
     In the form shown, the peripheral wall arrangement  106  of the main housing upper chassis  102  comprises a short substantially vertical left side outer wall  110  that is oriented in a front-to-rear direction of the main housing  100 , a substantially vertical left side inner wall  112  that is oriented in a front-to-rear direction of the main housing  100 , and an interconnecting wall  114  that extends between and interconnects the upper ends of the left side inner and outer walls  110 ,  112 . The main housing upper chassis  102  further comprises a short substantially vertical right side outer wall  116  that is oriented in a front-to-rear direction of the main housing  100 , a substantially vertical right side inner wall  118  that is oriented in a front-to-rear direction of the main housing  100 , and an interconnecting wall  120  that extends between and interconnects the upper ends of the right side inner and outer walls  116 ,  118 . The interconnecting walls  114 ,  120  are angled towards respective outer edges of the main housing  100 , but could alternatively be substantially horizontal or inwardly angled. 
     The main housing upper chassis  102  further comprises a short substantially vertical rear outer wall  122 . An upper part of the main housing upper chassis  102  comprises a forwardly angled surface  124 . The surface  124  has a recess for receipt of a display and user interface module. An interconnecting wall  128  extends between and interconnects the upper end of the rear outer wall  122  and the rear edge of the surface  124 . 
     The liquid chamber bay  108  has a substantially vertical wall portion  134  that terminates at a substantially horizontal floor portion  136  of the liquid chamber bay  108 . The left side inner wall  112 , right side inner wall  118 , wall portion  134 , and floor portion  136  together define the liquid chamber bay  108 . The floor portion  136  of the liquid chamber bay  108  has a recess to receive a heater arrangement such as a heater plate  140  or other suitable heating element(s) for heating liquid in the liquid chamber  300  for use during a humidification process. 
     The floor portion  136  of the liquid chamber bay  108  terminates short of the front edge of the left side inner wall  112  and the right side inner wall  118  to form a downwardly extending lip  142 . The lip  142  comprises a recess that enables a user to insert their finger under the front part of a handle portion  506  of a handle/lever  500  to lift the handle from a lowered position. The handle/lever  500  is for use in assisting with insertion of the liquid chamber  300  and for carrying the apparatus  10 , as will be described further below. The liquid chamber bay  108  further comprises opposed guide features in the form of left side and right side horizontally extending guide rails  144 ,  146  which extend toward a centre of the bay  108  from the respective left and right side inner walls  112 ,  118  to assist with guiding the liquid chamber  300  into position in the liquid chamber bay  108  as will be described in detail below. 
     The main housing lower chassis  202  is attachable to the upper chassis  102 , either by suitable fasteners or integrated attachment features such as clips for example. The main housing lower chassis  202  comprises a substantially vertical left side outer wall  210  that is oriented in a front-to-rear direction of the main housing  100  and is contiguous with the left side outer wall  110  of the upper chassis  102 , and a substantially vertical right side outer wall  216  that is oriented in a front-to-rear direction of the main housing  100  and is contiguous with the right side outer wall  116  of the upper chassis  102 . The main housing lower chassis  202  further comprises a substantially vertical rear outer wall  122  that is contiguous with the rear outer wall of the upper chassis  102 . 
     An underside of the lower housing chassis  202  comprises a bottom wall. A motor recess for receipt of a removable motor and/or sensor module is provided in the lower chassis  202 . A recess opening may be provided in the bottom wall to enable the motor and/or sensor module to be inserted in the recess. The motor and/or sensor module may be removable or non-removable. 
     With reference to  FIG.  3   , the removable liquid chamber  300  comprises an outer housing  302  defining a liquid reservoir, a liquid chamber gases inlet port  306  in fluid communication with the liquid reservoir, and a liquid chamber gases outlet port  308  in fluid communication with the liquid reservoir. A baffle may be provided internally in the liquid reservoir to define a flow path of gases through the liquid chamber  300 . A lower edge of the liquid chamber  300  comprises an outwardly directed annular flange  310  which interacts with the guide rails  144 ,  146  in the liquid chamber bay  108  for locating and retaining the liquid chamber  300  in the liquid chamber bay  108 . The flange  310  extends outwardly from the base of a peripheral wall  312  of the liquid chamber  300 . A bottom wall of the liquid chamber  300  is heat conducting and is adapted for resting on the heater plate  140  for heating liquid in the liquid chamber  300 . 
     The apparatus  10  comprises a connection manifold arrangement  320  for fluid coupling of the liquid chamber  300  to the apparatus  10 . The liquid chamber  300  can be fluidly coupled to the apparatus  10  in a linear slide-on motion in a rearward direction of the liquid chamber  300  into the liquid chamber bay  108 , from a position at the front of the housing  100  in a direction toward the rear of the housing  100 . The connection manifold arrangement  320  comprises a manifold gases outlet port  322  that is in fluid communication, via a fixed L shaped elbow  321 , with a gasflow passage from the motor and/or sensor module. The fixed L shaped elbow  321  receives gases from the outlet of the blower of the motor and/or sensor module, and connects to the inlet port  306  of the liquid chamber bay  300 . The lower portion of the elbow extends downwardly into the interior of the gasflow passage tube  264  ( FIG.  43   ), to receive gases from the motor and/or sensor module. 
     The connection manifold arrangement  320  further comprises a humidified gases return port  340  that is embodied in a removable elbow  342 . The removable elbow  342  is L-shaped, and further comprises a patient outlet port  344  for coupling to the patient breathing conduit  16  to deliver gases to the patient interface  17 . The manifold gases outlet port  322 , manifold gases inlet port  340 , and patient outlet port  344  each comprise soft seals such as O-ring seals or T-seals (not shown) to provide a sealed gases passageway between the apparatus  10 , the liquid chamber  300 , and the patient breathing conduit  16 . 
     The liquid chamber gases inlet port  306  is complementary with the connection manifold gases outlet port  322 , and the liquid chamber gases outlet port  308  is complementary with the connection manifold gases inlet port  340 . The axes of those ports are preferably parallel to enable the liquid chamber  300  to be inserted into the liquid chamber bay  108  in a linear movement. 
     The apparatus  10  has air and oxygen (or alternative auxiliary gas) inlets in fluid communication with the motor to enable the motor to deliver air, oxygen, or a suitable mixture thereof to the liquid chamber  300  and thereby to the patient. 
     Various aspects of the device will now be described in more detail. 
     In addition to the features described above, the apparatus has a component coupling that substantially inhibits a component (such as the removable elbow  342 ) from moving relative to the housing in a first direction, and a cover coupling that substantially inhibits a cover  5105   a ,  15105   a  from moving relative to the housing  100  in a second direction. The housing  100  and cover  5105   a ,  15105   a  may have a magnetic coupling, complementary locating features, or both magnetic coupling and complementary locating features. 
     In some embodiments having complementary locating features, the locating features of the housing and the cover may be interlocking features adapted to form an interlock. In other embodiments having complementary locating features, the locating features of the housing and the cover may not form an interlock. 
     In some embodiments the first and second direction are substantially perpendicular. For example, the first direction is substantially vertical and the second direction is substantially horizontal. The first direction may be about 75°, about 80°, about 85°, about 90°, about 95°, about 100°, or about 105°. The second direction may be about 15°, about 10°, about 5°, exactly horizontal, about −5°, about 110°, or about −15°. 
     With reference to the embodiment of the cover and screen carrier shown in  FIGS.  5  to  9   , the apparatus  10  has a magnetic coupling system arranged to magnetically couple a cover to a component of the housing  100 . The component of the housing  100  is the screen carrier  3102 , but may be any other suitable component of the housing  100 . Each of the housing  100  and cover  5105   a  having complementary locating features that are adapted to locate and align the cover  5105   a  and the apparatus  10  relative to each other to allow for said magnetic coupling. The locating features of the housing and the cover are interlocking features adapted to form an interlock. The interlock is an engagement between the cover  5105   a  and housing  100  that align the housing and cover in a predetermined orientation and maintain that orientation. The interlock prevents the housing and cover moving relative to each other in at least one direction, but allow movement in another direction. In some embodiments, the locating features may not be adapted to form an interlock. 
     The magnetic coupling system has at least one magnet  6003  associated with the screen carrier  3102  and at least one other magnet  6001  associated with the cover  5105   a . In the embodiment shown, the magnetic coupling system comprises multiple magnets  6001 ,  6003  associated with each of the housing  100  and cover  5105   a . The magnets  6001 ,  6003  are attached by interference fit and/or adhesive. In particular, the magnets  6001 ,  6003  are attached to upstands or supports  6005  and are received by the apertures  6006  provided by the supports  6005 . The apertures  6006  of the supports  6005  may have a reduced diameter, or platform, located away from an end of the support  6005  to prevent the magnets  6001 ,  6003  from being inserted too far, and to ensure the magnets  6001 ,  6003  are located. The supports  6005  of the cover  5105   a  have internal ribs or other projections that grip the magnets  6001  as they are inserted into the supports and provide an interference fit.  FIG.  8    shows the support having a generally hexagonal cross-section for receiving the magnets  6003 . The support  6005  may have other shaped cross-sections for receiving the magnets  6003  with an interference fit for example a quadrilateral or octagonal. 
     In an alternative embodiment, the magnetic coupling system may comprise at least one magnet  6003  associated with one of the screen carrier  3102  or cover and at least one ferrous part associated with the other of the housing  100  or cover. 
     The magnets  6001 ,  6003  are provided to the cover  5105   a  and screen carrier  3102  such that they attract when the cover  5105   a  is coupled to the screen carrier  3102  in a predetermined orientation of the cover  5105   a  relative to the screen carrier  3102 . The magnets  6001 ,  6003  also repel when the cover  5105   a  is offered to the screen carrier  3102  in at least one orientation other than said predetermined orientation. For example in a predetermined orientation the magnets  6001  provided to the cover  5105   a  may present an opposing magnetic pole (for example north) to the magnetic pole (for example south) of a magnet  6003  provided to the screen carrier  3102 , such that the cover  5105   a  and screen carrier  3102  are attracted to each other. Alternatively, or additionally in an orientation other than the predetermined orientation the magnets  6001  provided to the cover  5105   a  may present the same magnetic pole to the magnetic pole of a magnet  6003  provided to the screen carrier  3102 , such that the cover  5105   a  and screen carrier  3102  are repelled from each other (for example both poles could be north poles). 
     The magnets  6001  may be embedded in the cover  5105   a  and covered by a surface of the cover  5105   a , however in the embodiment as shown in  FIG.  7    the magnets  6001  are not covered by a surface of the cover  5105   a . The magnets  6003  are embedded in the screen carrier  3102  and covered by a surface of the screen carrier  3102 . The material covering the magnets is relatively thin so that the material does not significantly affect the strength of the bond between the magnet(s)  6001  of the cover  5105   a  and the magnet(s)  6003  of the screen carrier  3102 . Covering the magnets  6001 ,  6003  with the material provides aesthetic benefits and provides a relatively easy cleaning surface. The magnetic coupling system provide easy locating of the cover  5105   a  to the screen carrier  3102  for a user and also provide the user with tactile feedback that the cover  5105   a  is positioned correctly. 
     The locating features of one of the cover  5105   a  or screen carrier  3102  comprise at least one projection  6007  and the locating features of the other of the cover  5105   a  or screen carrier  3102  comprise at least one recess  6009 . The at least one projection and the at least one recess form the interlock. The interlocking features prevent relative movement between the cover and the housing  100  in an axis substantially parallel to a direction in which the elbow is removed. 
     In the embodiment shown, the cover  5105   a  comprises the recesses  6009  (one in each side wall  5152 ) and the screen carrier  3102  comprises the projection  6007 . The projection  6007  and recesses  6009  prevent, or at least substantially inhibit, the cover from moving relative to the screen carrier  3102  (or housing or the apparatus) for example when the chamber is removed from the apparatus  10 —the removable elbow is held beneath the cover  5105   a  as described below and is also prevented, or at least substantially inhibited, from being removed when the chamber is removed. 
     The recesses  6009  comprise angled rear and front faces  6009   a ,  6009   c  with a generally flat portion  6009   b  between. The projection comprises angled rear and front faces  6007   a ,  6007   c  that are complementary to the angled rear and front faces of the recess with a generally flat portion  6007   b  between. As shown in  FIG.  6   , the rear faces  6007   a ,  6009   a  can define an angle  6009   e  and the front faces  6007   c ,  6009   c  can define an angle  6009   d . The angle  6009   d ,  6009   e  is measured with reference to a horizontal axis and may be between a nearly horizontal angle to a generally vertical angle. For example, the angle  6009   d ,  6009   e  may be between about 5 degrees to about 90 degrees, about 10 degrees to about 85 degrees, about 15 degrees to about 80 degrees, about 20 degrees to about 75 degrees, about 25 degrees to about 70 degrees, about 30 degrees to about 65 degrees, about 35 degrees to about 60 degrees, about 40 degrees to about 55 degrees, about 45 degrees to about 50 degrees. The embodiment shown has one projection  6007  in the form of a ridge that extends across the screen carrier  3102 . In an alternative embodiment, the screen carrier  3102  or other component of the housing  100  may have more than one projection  6007 . 
       FIG.  9    shows the rear face  6007   a  of projection  6007  is of a shorter length than the length of the front face  6007   c  of projection  6007 . This may assist in the orientation of the cover  5105   a  and the screen carrier  3102 , as there is only one orientation in which the cover  5105   a  can engage with top surface of the carrier. The recesses and projection may have other asymmetrical profiles, such as a curved profile. It will be appreciated that the front face  6007   c  of the projection  6007  may be shorter than the length of the rear face  6007   a  of projection  6007 . 
       FIG.  9    also shows that screen carrier having bosses  6015 . The bosses  6015  may allow for the passage of a fastener to couple the screen carrier  3102  to part of the apparatus. The bosses  6015  may stand proud, or be recessed from a surface of the screen carrier  3102 . Such a configuration may allow for prevention of the accumulation of material, and allow for easy cleaning of the surface of the screen carrier  3102 . 
     The locating interlocking features may be adapted to prevent relative movement between the cover  5105   a  and the housing  100 . In particular, the locating features comprise the side walls  5152  of the cover  5105   a . The locating features may comprise a back wall  5154  and may additionally or alternatively comprise a front wall of the cover  5105   a . The lower surface of one or more of the walls may also be a locating feature that interacts with a corresponding surface of the housing. The back wall  5154  is recessed from an edge of the cover  5105   a . The front wall, if provided, may also be recessed from an edge of the cover  5105   a . This helps ensure better engagement between the cover  5105   a  and the screen carrier, and acts as a barrier to water ingress. Once engaged, the cover  5105   a  cannot move, or is at least substantially inhibited from moving relative to the housing  100 . A recessed back wall  5154  provides for a region of the cover  5105   a  which can be grasped by a user, and may help in the removal and/or engagement of the cover from or to the screen carrier  3102 . 
     With reference to  FIG.  2   , the cover  5105   a  covers, retains, assists with the retention of and/or positions a component of the apparatus. In particular, the cover  5105   a  covers, retains, assists with retention of, and/or positions the removable elbow  342 . 
     It will be understood that the direction of movement that is being prevented is the direction of movement required for removing the removable elbow  342 . That is, the direction of movement being prevented is substantially perpendicular to the direction of movement for attaching the cover: the cover moves vertically to attach over the elbow, and then prevents horizontal movement of the removable elbow  342 . 
       FIG.  11    shows the removable elbow  342  for use in the flow therapy apparatus. The elbow has an inlet port  340  and an outlet port  344 . The elbow  342  has a pneumatic and/or an electrical connection. In particular, the elbow has a PCB connector  366  and a chimney portion  368   a . The elbow has a plastic support portion  374  with angled edges to allow for recesses on the PCB connector  366 . The base at the inner end of the horizontal limb (corresponding to the manifold gases inlet port  340 ) of the removable elbow has an upwardly curved region  340   c  prior to the bend in the elbow to assist with tooling. The elbow comprises depressions  370  on part of the gasflow outlet  344  for engagement with complementary protrusions on a sliding locking collar connected to the heated patient interface tube  16 . 
     As described above, the elbow  342  is a removable component. The cover  5105   a  may alternatively cover, retain, and/or position other elements of the flow path. The cover  5105   a  has an aperture  6019  to allow for passage of the outlet port  344  of the elbow  342 . 
     The cover  5105   a  has a lead-in feature  6017  to engage part of the elbow upon initial engagement, to ensure correct alignment between the cover  5105   a , the breathing apparatus, and the removable elbow  342 . The lead-in feature is a generally oval shaped aperture  6017  that connects with the aperture  6019  that receives the elbow  342 . The lead-in feature engages with one or more of the features of the removable elbow for example pneumatic or electrical connection features of the removable elbow. In the embodiment shown, the lead-in feature  6017  receives the chimney portion  368   a  of the elbow  342 . Once assembled, the cover  5105   a  prevents the elbow  342  from being removed in a horizontal direction. 
     The screen carrier  3102  also has lead-in features  6013  to engage part of the fixed elbow  321  upon initial engagement, to ensure correct alignment between the screen carrier  3102 , the breathing apparatus, and the fixed elbow  321 . The lead-in features are guide slots that engage with one or more of ridges  321   a  of the fixed elbow  321  ( FIG.  4   ). 
     The projection  6007  and complementary recesses  6009  associated with the screen carrier  3102  and the cover  5105   a  allow the cover  5105   a  and screen carrier  3102  to be assembled together in a predetermined orientation of the cover  5105   a  relative to the screen carrier  3102  and prevent the cover  5105   a  and screen carrier  3102  being assembled together when the cover  5105   a  is offered to the screen carrier  3102  in at least one orientation other than said predetermined orientation.  FIG.  5    shows that the side walls  5152  of the cover  5105   a  are asymmetrical about a transverse axis. 
     When the removable elbow  342  is coupled to the housing  100 , it can only be removed horizontally, and therefore the coupling with the housing  100  inhibits motion in the vertical direction. If a vertical force is applied to the removable elbow  342  (such as when the tube is removed) then the elbow coupling will prevent the removable elbow  342  from being removed. 
     Due to the removable elbow  342  passing vertically through the cover  5105   a , the cover  5105   a  and the removable elbow  342  are prevented from moving relative to each other in a horizontal direction. 
     When the cover  5105   a  is coupled to the housing  100  with an interlock it can only be removed vertically, and therefore inhibits motion in the horizontal direction. If a horizontal force is applied to the removable elbow  342  (such as when the chamber is removed) then the configuration of the cover coupling to the housing  100  over the removable elbow  342  prevents the elbow from being removed. 
     When the cover  5105   a  couples to the housing  100  with a magnetic coupling, then the magnets inhibit (but may not fully prevent) motion in a horizontal direction. In this configuration, the retaining force of the elbow connection would also inhibit (but may not fully prevent) motion in the horizontal direction. If a horizontal force is applied to the removable elbow  342  (such as when the chamber  300  is removed) then the configuration of the cover coupling to the housing  100  over the removable elbow  342  inhibits this force and acts as a retaining feature. Additionally, the retaining force of the removable elbow  342  would also inhibit this force, and would also act as a retaining feature. One or a combination of the forces from these retaining features would be enough to prevent the removable elbow  342  from being removed. 
       FIG.  5    shows the cover  5105   a  comprises an aperture  6011  extending through the top of the cover  5105   a . This aperture is an optional feature and the cover  5105   a  may comprise additional apertures, if required. The aperture may provide for connection to a port or other connection of the screen carrier  3102  through the cover  5105   a.    
     The cover  5105   a  may be coupled to the screen carrier  3102 , and thereby to the main housing, by a flexible tether  7000  shown in  FIG.  10   . The tether comprises an elongate body  7002 , an aperture  7004  at or toward a first end of the tether, and enlarged head  7006  at or toward an opposite second end of the tether. The tether  7000  is coupled to the cover  5105   a  by inserting the enlarged head  7006  through a slot (not shown) in the cover  5105   a . The enlarged head inhibits removal of the tether from the cover  5105   a . The tether  7000  is coupled to the carrier  3102  by inserting the first end of the tether between the carrier  3102  and the upper chassis  102  so its aperture  7004  is aligned with the respective aperture, and is maintained in position by the fastener that is used to fasten the carrier  3102  to the upper-chassis  102 . The tether may be manufactured from a suitable resilient and robust material, such as TPU for example. The cover  5105   a  may pivot at one end relative to the carrier  3102 . The cover  5105   a  may comprise a hook (not shown) which one end of the tether can connect to, the screen carrier  3102  may also have a hook or other feature to which the other end of the tether can be connected. In an alternative embodiment, one end of the tether may connect to the removable elbow  342  and the other end may connect to the cover. 
     With reference to  FIGS.  12  to  17   , another embodiment of the cover and the screen carrier will now be described. Unless described below, the features and functions should be considered to be the same as those described above and like numerals are used to indicate like parts with the addition of 10000. 
     This embodiment has a magnetic coupling system with at least one magnet (not shown) associated with the screen carrier  13102  and at least one other magnet associated with the cover  15105   a . The magnetic coupling system may comprise multiple magnets associated with each of the housing  100  and cover  15105   a . Similar to the previously described embodiment, the magnets are attached to upstands or supports  16005  and are received by the apertures  16006  provided by the supports  16005 . 
     The locating features of the housing  100  and the cover  15105   a  may be interlocking features adapted to form the interlock. In particular, the locating feature of one of the cover  15105   a  or housing  100  comprises at least one projection  16007  and the locating feature of the other of the cover  15105   a  or housing  100  comprises at least one recess or aperture  16009 , the projection  16007  and recess  16009  forming the interlock. In this embodiment, the cover  15105   a  has two projections  16007  that are received by complementary recesses  16009  in the screen carrier  13102 . In alternative embodiments, the cover  15105   a  may have one projection that is received by one recess in the screen carrier  13102 , or may have three or more projections that are received in three or more complementary recesses in the screen carrier  13102 . The recesses and/or projections have rounded or chamfered edges to act as lead in features when assembling the cover  15105   a  with the housing  100 . This allows the cover  15105   a  to be slightly out of position when the projections first contact the recesses  16009 , with the cover  15105   a  then moving into the correct alignment when the projections fully interlock or couple with the recesses. The recesses  16009  are formed in bosses  16009   a , but may alternatively be formed in the planar surface of the screen carrier  13102 . In this embodiment, the locating features also comprise the lower surface of the side walls, which is a tapered surface  16009   c . The tapered surface  16009   c  assists with guiding the cover into place due to its interaction with the corresponding tapered surface of the housing. 
     As mentioned in relation to the earlier described embodiment, the locating features may comprise a back wall and may additionally or alternatively comprise a front wall of the cover, if provided. 
       FIG.  17    shows the cover  15105   a  and screen carrier  13102  fully assembled with the projections  16007  sitting within the recesses  16009 . The projections  16007  prevent, or at least substantially inhibit, movement of the cover  15105   a  relative to the screen carrier  13102  in any direction other than directly vertically. When assembled with the removable elbow  342 , the projections  16007  prevent, or at least substantially inhibit, movement in the horizontal direction that would be required to remove the removable elbow  342 . As such, the cover  15105   a  retains the removable elbow  342  and prevents removal of the removable elbow  342  without first removing the cover  15105   a.    
     With reference to  FIGS.  18  to  20   , another embodiment of the cover and the screen carrier will now be described. Unless described below, the features and functions should be considered to be the same as those described in relation to  FIGS.  12  to  17    and like numerals are used to indicate like parts with the addition of 10000. 
     In this embodiment, the cover  25105   a  and screen carrier  23102  have a magnetic coupling system. This embodiment does not have projections and recesses that form an interlock. 
     In this configuration, there is no aperture corresponding to the aperture  6011  of the previously described embodiment. Additionally, this embodiment does not have an angled rear face or a generally flat portion. While this configuration does not provide the interlocking mechanism of other embodiments, the magnetic coupling provides a retaining force that resists horizontal movement of the removable elbow  342 , for example when the chamber  300  is removed. Additionally, the coupling between the removable elbow  342  and the housing  100  would also provide a retaining force that resists horizontal movement. One or more of these retaining forces is preferably greater than the force required to remove the chamber  300 , such that removing the liquid chamber  300  would not pull the removable elbow  342  out of place. 
     In addition, the locating features may comprise a back wall and may additionally or alternatively comprise a front wall of the cover  25105   a , if provided. 
       FIG.  20    illustrates this embodiment of the cover assembled with the screen carrier  13102 . 
     Another feature shown in  FIG.  20    is an alternative form of the screen carrier  13102 . In the previously described embodiment, the screen was recessed such that no part of the screen was higher than the other components of the apparatus. In this configuration, the screen is raised such that the lower end of the screen is level with the upper surface of the screen carrier  13102 , with the rest of the screen angled to extend above the other components of the apparatus. This prevents, or at least substantially inhibits, the screen from being visually obstructed by the other components of the apparatus, and allows for a user to more easily view the user interface  14  from a distance. 
     With reference to  FIGS.  21  to  26   , the apparatus  10  may have a battery (not shown) in a battery cover  201  that is coupled to the exterior back wall of the apparatus  10 . The battery cover  201  has a flange  203  that overlaps the motor and/or sensor module to prevent the motor and/or sensor module from being removed before the battery is removed. The battery cover  201  may have one or more apertures  205  formed in upstands  206  on the flange  203 . Fasteners could be inserted through the apertures  205  to fasten the flange  203  to the lower chassis of the apparatus  10 . 
     The battery cover  201  may be removable in order to allow access to the battery. However, in another embodiment, the battery cover  201  may not be easily removable, but instead require disassembly of various fasteners (as described above). This would prevent the battery from being removed by a regular user, as removal of the battery cover would typically be for replacing the battery, which would only be done every couple of years by a technician. Additionally, certain electronic components may be exposed when the battery and battery cover are removed, and as such the fasteners are useful in preventing unwanted disassembly. 
     The battery cover  201  may have an upper horizontal edge  207  that acts as a liquid deflector for preventing water from dripping onto various electrical connections. A similar feature  209  could be incorporated below the first feature for a secondary electrical connection, such as a connector for a battery charger. 
     The apparatus  10  also has a valve retention tab  211  that overlaps the valve module that prevents removal of the valve module when assembled. 
     The cover  201  may be provided with a groove  213  and/or at least one ridge  215  around its upper edge. This groove  213  can extend down at least a portion of the side of the cover  201 . The groove  213  and/or ridge could interact with a complementary shaped ridge  217  and/or groove on the housing  100  of the apparatus  10 . When assembled, the interaction between the two complementary features provides a tortuous path to prevent the ingress of liquid and oxygen into the electrical components. 
     The battery cover may include a ledge  219  for supporting the battery at the correct height and prevent the battery from moving around during use. The ledge could be supported by one or more structural ribs  221 . 
     The battery cover  201  could be constructed with a portion  223  that extends below the base level of the apparatus  10 . This allows for a larger battery to be used, which would improve battery life and/or maximum power output. Because the extended portion may interfere with allowing the apparatus  10  to be supported on a flat surface, this configuration would likely be used when the apparatus  10  is intended to be connected to a moveable stand via a mounting feature on the side of the apparatus  10 . The apparatus  10  may be mounted to a moveable stand when the apparatus  10  is required to frequently move around with the patient, and as such a larger and more powerful battery would be increasingly useful. 
       FIG.  24    shows the corresponding section of the apparatus  10  that the battery cover  201  couples with. The housing  100  has a complementary ridge and/or groove that interacts with the groove and/or ridge on the cover. When assembled, the interaction between the two complementary features provides a tortuous path to prevent the ingress of liquid and oxygen into the electrical components. 
     The housing  100  has complementary apertures  225  that surround the apertures on the battery cover to allow a fastener to be inserted through both apertures and couple the housing  100  with the battery cover. The coupling of the apertures additionally acts as a locating feature to ensure the cover is in the correct position relative to the housing  100  prior to the fastener being added. The fastener being used instead of some form of mechanical clip increases the difficulty of removing the battery cover and helps to prevent unwanted disassembly of the device. 
     The apparatus has a small gap  227  at the base of the housing  100  wall to allow for the tab on the battery cover to overlap the motor/sensor module. 
     The apparatus housing  100  may have angle features  229  on the inner surface of the wall that allow for initial receipt of the battery cover in a variable position, but then guide the battery cover into the correct position as the cover is further inserted into its final position. This could match up with a similar angled feature  231  on the cover. 
     Humidifier/Liquid Chamber Bay and Handle Arrangement 
     The liquid chamber bay  108  and handle arrangement will now be described in more detail with reference to  FIGS.  2 , and  27  to  48   . 
     As discussed, the liquid chamber bay  108  comprises opposed left side and right side guide rails  144 ,  146  which extend toward a centre of the bay  108  from the respective left and right side inner walls  112 ,  118 . The guide rails  144 ,  146  assist with guiding the liquid chamber  300  into position in the bay  108 . The guide rails  144 ,  146  are parallel to the floor  136  of the liquid chamber  300  and/or with the upper surface of the heater plate  140 , to enable the flange  310  of the liquid chamber  300  to slide therebetween. 
     The handle arrangement has a handle  500  for assisting with insertion and/or retention and/or removal of the liquid chamber  300  in and/or from the chamber bay  108 . Different configurations may be configured for assisting with one, two, or all of insertion, retention, removal of the liquid chamber  300  in and/or from the liquid chamber bay  108 . The handle is movable from a first position to a second position. In the form shown, the first position is a fully lowered or closed position (e.g.  FIG.  2   ) and the second position is a fully raised position (e.g.  FIG.  29   ). 
     The handle  500  is a single sided configuration. That is, only one side of the handle  500  is movably connected relative to the main housing  100  of the flow therapy apparatus  10 , whereas there is no pivot connection of the other side of the handle  500  to the main housing. In the form shown, the left side of the handle  500  is pivotally connected relative to the main housing  100 . However, in an alternative configuration, only the right side may be pivotally connected to the main housing  100 . The handle  500  is pivotally and translationally connected to the main housing, so that the handle moves on a path having a varying radius relative to the main housing. 
     The handle  500  has a left side arm  502  that is pivotally and translationally attached relative to the left inner side wall  112  of the upper chassis  102 . The left side arm  502  is configured to be substantially flush with the interconnecting wall  114  when the handle  500  is in the lowered or closed position of  FIGS.  2 ,  31 ,  35 ,  39 ,  43 , and  48   . Rather than a right side arm, the handle  500  further comprises a right side member  504  that is shorter than the left side arm  502 , and that is not pivotally attached to the right inner side wall  118  of the upper chassis  102 . The right side member  504  is configured to be substantially flush with the interconnecting wall  120  when the handle  500  is in the lowered or closed position. The main housing is provided with recesses to enable the left side arm  502  and right side member  504  to be substantially flush with the interconnecting walls. In the form shown, the left side member  502  is longer than the right side member  504 , so a spacer member  120 ″ is mounted to the upper chassis  102  and sits substantially flush with the interconnecting wall  120  and the right side member  504  when the handle  500  is in the lowered or closed position. The spacer member  120 ″ may carry a label or other indicia with information representing the device and/or its user. The left side arm  502  will not be substantially flush with the interconnecting wall  114  and the right side member  504  will not be substantially flush with the spacer member  120 ″ when the handle is not fully closed/lowered, thereby providing a visual cue that the handle  500  is not fully closed/lowered. 
     A terminal part of the handle has a cross-member handle portion  506  that interconnects the forward ends of the left side arm  502  and the right side member  504  and forms an engagement region for grasping by a user&#39;s fingers. When the handle  500  is in the raised position as shown in  FIGS.  29 ,  34 ,  38 , and  42    for example, the cross-member  506  can act as a carrying handle for the user to lift and carry the apparatus  10 . The liquid chamber  300 —shown in  FIG.  30    for example—can be inserted into or removed from the liquid chamber bay  108  when the handle  500  is raised. When the handle  500  is in the lowered position, it inhibits or prevents removal of the liquid chamber  300  from the liquid chamber bay  108 . 
     Rather than having the right side member  504 , the handle  500  may terminate at the right side of the cross-member  506 . However, having the rearwardly directed member  504  is preferred, as it reduces the likelihood of the apparatus  10  being dropped while it is being carried. 
     In the closed or fully lowered position of the handle  500 , the cross-member  506  is located at the front of the main housing and encloses a portion of the liquid chamber bay  108 . The handle  500  and/or housing  100  may have a positive engagement feature to positively engage the handle/ 500  in the lowered or closed position. For example, the cross-member  506  of the handle  500  may have a recess or protrusion, and the housing may have a complementary protrusion or recess which is engaged with the recess or protrusion of the handle  500  when the handle is in the lowered position. With the handle  500  in the lowered or closed position, a portion of the cross-member  506  projects sufficiently above the floor of the liquid chamber bay  108  and above the flange  310  of the liquid chamber  300  that it prevents the liquid chamber  300  from being slid forward and removed from the liquid chamber bay  108 . The liquid chamber bay  108  comprises guide rails  144 ,  146  to prevent the liquid chamber  300  from being lifted and removed vertically from the liquid chamber bay  108  when the handle  500  is in the lowered or closed position. 
     When the liquid chamber  300  is positioned in the liquid chamber bay  108  and the handle  500  is in the lowered or closed position, engagement features  500   a ,  500   b ,  500   c  on the handle  500  engage with the liquid chamber  300  to assist with maintaining the sealing engagement between the ports. Referring to  FIGS.  45 ,  46 , and  48   , the engagement features comprise a first engagement feature  500   a  in the form of a scalloped recess on the lower inner side of the left side arm  502 , a second engagement feature  500   b  in the form of a scalloped recess on the lower inner side of the right side member  504 , and a third engagement feature  500   c  in the form of a scalloped recess on the lower inner side of the cross-member  506 . The scalloped regions  500   a ,  500   b ,  500   c  engage against upper edges of the liquid clamber  300 . The scalloped recesses may also assist with inserting the liquid chamber  300  into the liquid chamber bay  108  by contacting the upper edges of the liquid chamber housing and pushing the upper portion of the liquid chamber further into the liquid chamber bay  108  as the handle  500  is lowered. 
     While three engagement features  500   a ,  500   b ,  500   c  are shown, fewer or more engagement features could be used. For example, only the front engagement feature  500   c  may be provided, or alternatively, only the side engagement features  500   a ,  500   b  may be provided. The scalloped recesses enable the handle  500  to apply force against the liquid chamber  300  when the handle  500  is in the lowered position, while enabling a close fit of the handle  500  around the liquid chamber  300  which reduces the likelihood of items inadvertently being dropped into the liquid chamber bay  108 . In other configurations, engagement features may not be provided on the handle  500 . Instead of being scalloped recesses, the engagement features  500   a ,  500   b ,  500   c  could have a different form. For example, one or more of the engagement features could comprise a protrusion that extends from part of the handle  500 . 
     It can be seen from  FIG.  2    that a substantial part of the liquid chamber  300  is exposed and visible from the front and top of the apparatus when the handle  500  is in the lowered position. The liquid chamber  300  will typically be transparent, and by having a substantial part of the liquid chamber  300  exposed and visible, a user will readily be able to see the liquid level in the liquid chamber without needing to raise the handle  500  from the lowered position. 
     The guide rails  144 ,  146  may have a curved shape and/or upwardly angled leading portions  144   a  ( FIG.  3   ) to assist with easing the liquid chamber  300  into the liquid chamber bay  108 . Alternatively, or additionally, the guide rails  144 ,  146  may be oriented to be non-parallel with a base of the chamber bay  108 , and thereby with the heater plate. 
       FIGS.  30  to  46    show details of the pivot arrangement of the handle  500 . A rearward portion of the left side arm  502  is connected to a pivot arm  502   d . The pivot arm  502   d  comprises a forward arcuate portion  502   e  that extends downwardly and rearwardly from the left side arm  502  when the handle  500  is in the lowered or closed position. A rearward part of that forward arcuate portion  502   e  is connected to a body portion  502   f  that extends upwardly and forwardly therefrom when the handle is in the lowered or closed position. The body portion  502   f  has a tapered configuration with a base of the body portion being relatively small and an upper terminal portion of the body portion being relatively large. The body portion  502   f  is relatively large so as to provide additional mass to help stabilise the handle in the raised position and reduce side-to-side movement of the handle in that position. 
     A spacing is provided between the majority of the pivot arm  502   d  and the body portion  502   f . An upper end of the body portion  502   f  comprises two pivot protrusions, a rear, outwardly directed, first pivot protrusion  502   b ′ and a forward, inwardly directed, second pivot protrusion  502   b ″. Each pivot protrusion  502   b ′,  502   b ″ extends from the body portion  502   f  and has an exposed axial length EL and a transverse dimension OD. The transverse dimension OD is greater than the axial length. For example, the transverse dimension OD may be at least twice the axial length EL, and may be three times or greater. An example transverse dimension OD is about 12 mm, but any other suitable transverse dimension could be used. The pivot protrusions are shown as being substantially cylindrical, but could alternatively be a different shape. 
     The rear pivot protrusion  502   b ′ is received in a first pivot cavity  502   c ′ which is shown in  FIGS.  34  to  37   . The first pivot cavity  502   c ′ comprises a slot or a channel with closed ends. The first pivot cavity  502   c ′ is a general 3-shaped. A rearward portion of the first pivot cavity  502   c ′ which corresponds to the position of the rear pivot protrusion  502   c ′ when the handle is in the lowered position or is initially raised, has a downwardly and forwardly extending orientation, and is either substantially linear or has a relatively large radius of curvature. An intermediate portion of the first pivot cavity  502   c ′ undergoes a direction change and has a relatively small radius of curvature. The forward portion of the first pivot cavity is upwardly and forwardly directed, is shorter than the rear portion, and is either substantially linear or has a relatively large radius of curvature. As shown in  FIGS.  34  to  37   , as the handle  500  is raised from the lowered position, the rear pivot protrusion  502   b ′ initially follows a downward and forward substantially linear path LP 1  ( FIGS.  34  and  35   ), undergoes the direction change DC ( FIG.  36   ), and then follows a shorter upward and forward linear path LP 2  ( FIG.  37   ). The rear pivot protrusion  502   b ′ is configured to be retained in the first pivot cavity  502   c ′, but to substantially freely move along the length of that pivot cavity. The ends of the first pivot cavity  502   c ′ are closed so that the pivot protrusion  502   b ′ cannot exit either end of the pivot cavity. 
     The front pivot protrusion  502   b ″ is received in a second pivot cavity  502   c ″ as shown in  FIGS.  38  to  41   . The second pivot cavity  502   c ″ comprises a slot or a channel, and is a relatively horizontal pivot cavity extending substantially in a forward-rearward direction of the apparatus. The second pivot cavity  502   c ″ is either substantially linear or is generally arcuate with a large radius of curvature so that the front pivot protrusion  502   b ″ follows a substantially arcuate path AP as the handle is moved between the lowered position and the raised position. In the form shown, the second pivot cavity  502   c ″ substantially follows the curvature of the left side interconnecting wall  114 , and has a convex curvature relative to a position above the pivot cavity. The front pivot protrusion  502   b ″ is configured to be retained in the second pivot cavity  502   c ″, but to substantially freely move along the length of that pivot cavity. When the handle  500  is raised from the lowered position, initially the front pivot protrusion  502   b ″ does not move rearward from the front of the second pivot cavity  502   c ″, despite the rear pivot protrusion  502   b ′ moving downward and forward in the first pivot cavity  502   c ′ ( FIGS.  34 ,  36 ,  39 ,  40   ). When the rear of the pivot protrusion  502   b ′ is in the direction change DC region of  FIG.  36   , the front pivot protrusion  502   b ″ has moved rearwardly to less than halfway along the length of the second pivot cavity  502   c ″ ( FIG.  40   ). As the handle  500  is then moved to the fully raised position, the rear pivot protrusion  502   b ′ moves to the position near the top of the front portion of the first pivot cavity  502   c ′ shown in  FIG.  37    and the forward pivot protrusion  502   b ″ moves to the position at the rear of the second pivot cavity  502   c ″ shown in  FIG.  41   . 
     The rear and front pivot protrusions  502   b ′,  502   b ″ may comprise members that are received in corresponding apertures in the body portion  502   f  of the handle. Alternatively, the pivot protrusions may be integrally formed with the body portion  502   f.    
     The apparatus comprises a handle retainer  498 , which is shown most clearly in  FIGS.  30  to  41   . The handle retainer comprises a substantially hollow body that has an upper edge  498   a  corresponding substantially in shape to the underside of the interconnecting wall  114 . However, the handle retainer  498  projects further forward than a front edge of the interconnecting wall  114 , so that an aperture  498   b  in the handle retainer  498  is positioned in front of the interconnecting wall  114 . The shape of the aperture  498   b  corresponds substantially to that of the forward arcuate portion  502   e  of the pivot arm. The aperture  498   b  is sized so as to be only slightly larger than that of the forward arcuate portion  502   e  of the pivot arm, so that there is no space for foreign objects to be entered into the aperture when the handle is raised. 
     The handle retainer  498  comprises a base wall that opens into a liquid drain channel  498   c  that extends down the side of the housing. The liquid drain channel  498   c  may be in communication with a cavity in the base of the main housing, so that any liquid that enters the handle mechanism can drain through the liquid drain channel  498   c  and exit through apertures in the base of the main housing  100 . The handle retainer provides a diffusion-based mechanism to remove liquid/gas. Additionally, the holes in the chassis parts for receipt of the handle retainer/handle are small and self-contained and are spaced apart from sources of gas to reduce the likelihood of gas leakage into the case of the apparatus. Apertures do not need to be punched into the walls of the chassis parts for receipt of the handle pivots. 
     The handle retainer  498  seals between the upper chassis  102  and the lower chassis  202  in the region of the handle retainer. In an alternative configuration, the handle retainer  498  could seal against the upper chassis  102  and/or the handle  500  to prevent liquids/gases from entering the case or the handle retainer. Face seals, convoluted path seals, and/or tongue and groove arrangements could be provided for example. 
     As shown in  FIG.  38   , an inner portion of the right side wall of the handle retainer comprises a ledge  498   e ′ that forms a base of the second pivot cavity  502   c ″. As shown in  FIG.  43   , an underside  498   e ″ of an inner wall portion of the upper chassis  102  forms an upper edge of the second pivot cavity  502   c″.    
     To mount the handle  500  to the apparatus, the handle  500  is positioned in the handle retainer  498  so that the second pivot protrusion  502   b ″ is positioned on the ledge  498   e ′ and so that the first pivot protrusion  502   b ′ is positioned in the first pivot cavity  502   c ′. The handle and handle retainer can then be moved into engagement with the upper chassis part  102  such that apertures in the handle retainer are aligned with apertures in the upper chassis  102 , and fasteners such as screws or the like are used to fasten the components together. Therefore, the handle retainer  498  becomes part of the main housing  100  of the apparatus when the handle retainer is fixed to the upper chassis. 
     Movement of the pivot protrusions  502   b ′,  502   b ″ and the handle  500  can be split into several phases as shown in  FIGS.  30  to  41    and discussed above. Those phases are represented graphically in  FIG.  44   . Referring to  FIG.  44   , the path of movement of the terminal end  506  of the handle relative to the apparatus housing is shown by curve TEP. That path has a varying radius of movement of the terminal end of the handle from a fully lowered to a fully raised position. In the form shown, the path is generally elliptical; that is, it follows the shape of a part of an ellipse. In the form shown, the path corresponds to slightly over one quarter of an ellipse. The radial lines represent a general transition point from one phase to another or indicate the beginning and ending of a phase relative to the position of the end of the handle. 
       FIGS.  31 ,  35 , and  39    show the handle as it has been moved away from a fully lowered position. During this first phase P 1  of movement, the second pivot protrusion  502   b ″ remains at the terminal forward end of the second pivot cavity  502   c ″. The first pivot protrusion  502   b ′ is caused to translate downward and forward along linear path LP 1 . This urges the end  506  of the handle forward and upward away from the lowered/closed position. The initial movement of the terminal end of the handle  500  is out and away from the housing so that the handle does not collide with the housing at either end. 
       FIGS.  32 ,  36 , and  40    show the handle as it has been moved further away from the closed position. During this second phase P 2  of movement, the first pivot protrusion  502   b ′ has translated further downward in the first pivot cavity  502   c ′ relative to the housing and is undergoing the direction change DC. The second pivot protrusion  502   b ″ has started to translate rearwardly along the second pivot cavity  502   c ″. This results in a relatively steep upward and rearward movement of the terminal end  506  of the handle relative to the housing. 
     As shown in  FIGS.  33 ,  37 , and  41   , at the end of the third phase P 3  of movement, the second pivot protrusion  502   b ″ has reached the rear end of the second pivot cavity  502   c ″ and the first pivot protrusion  502   b ′ has reached the upper forward end of the first pivot cavity  502   c′.    
     The first pivot protrusion  502   b ′ is fully constrained in the first pivot cavity  502   c ′ throughout movement of the handle  500 . 
     The handle  500  and housing  100  could have a different configuration of pivots and pivot cavities, while still providing the moment phases shown in  FIG.  44   . 
     The handle  500  is designed so that when the handle is in the fully raised position and is being used to carry the apparatus  10 , the handle is located generally above the centre of gravity of the apparatus including a liquid chamber containing liquid. This reduces tilting or swinging of the apparatus as the apparatus is being carried, making the apparatus easier to carry and reducing the likelihood that liquid will enter the apparatus from the liquid chamber, and acting to keep the apparatus generally level whilst it is being carried. The apparatus may be configured so that the raised handle is over or generally over the centre of mass with a full liquid chamber inserted. The apparatus is heaviest with a full liquid chamber, and that is when liquid is most likely to spill back into the apparatus. Alternatively, the apparatus may be configured so that the raised handle is over or generally over the centre of the mass of the apparatus with a partially full liquid chamber inserted, such as a half-full liquid chamber for example. 
     Depending on whether the fully raised handle is positioned directly over the centre of mass of the apparatus, or close to that position, the base of the apparatus may sit substantially flat while the apparatus is being carried, or alternatively may be slightly angled while the apparatus is being carried. The force provided by the user in holding the apparatus is not offset significantly from the centre of mass. This also means that the liquid in the liquid chamber  300  remains substantially horizontal, reducing the risk of liquid flow into the gasflow path. The generally elliptical movement path of the handle  500  enables the handle to move from the fully lowered position to a fully raised position located generally above and generally in-line with the centre of mass. Additionally, the movement path is such that there is a substantially constant spacing between the handle and an upper portion of the housing, at least between a partly-raised position ( FIG.  31   ) and fully raised position ( FIG.  33   ) of the handle, to minimise possible pinch points between the handle and the housing. 
     The handle is designed so that the pivot protrusions  502   b ′,  502   b ″ do not carry the apparatus load when the handle is in the fully lowered position or in the fully raised position. 
     The housing  100  of the apparatus  10  and the handle  500  comprise complementary interlock features. In the form shown, the body portion  502   f  of the handle  500  comprises an interlock feature  503  and the underside of the upper chassis portion  102  comprises an interlock feature  103 . The complementary interlock features  103 ,  503  are arranged such that when handle  500  is in the raised position and upward force is applied to the handle  500  relative to the housing  100 , the interlock features  103 ,  503  engage with each other. When the handle  500  is in the raised position but upward force is not applied to the handle  500  relative to the housing  100 , the interlock features  103 ,  503  are disengaged from each other. 
     In one configuration, the interlock features  103 ,  503  comprise a projection on one of the handle  500  and the housing  100 , and a complementary recess on the other of the handle  500  and the housing  100 . In the form shown, the interlock features comprise a plurality of projections  503   a ,  503   b ,  503   c  on the handle  500  that extend generally radially relative to the rear pivot protrusion  502   b ′, and a plurality of complementary recesses  103   a ,  103   b ,  103   c  on the underside of the interconnecting wall  114  of the upper chassis portion  102  ( FIG.  43   ). While three projections and recesses are shown, it will be understood that one, two, three, four, or more projections and recesses can be provided. It will also be understood that either or both components could have the projections and/or recesses. 
     When the handle  500  is in the fully raised position ( FIGS.  33 ,  37 ,  41   ) and no upward force is being applied to the handle  500 , the second pivot protrusion  502   b ″ will rest on the lower wall  498   e ′ of the second pivot cavity  502   c ″, the first pivot protrusion  502   b ′ will be positioned slightly below the upper end of the front of the first pivot cavity  502   c ′, and the interlocking features  103 ,  503  will not be engaged with each other. When a user applies upward force to the handle  500  relative to the housing, such as by lifting the apparatus by the handle  500 , the handle  500  will move upwardly relatively to the housing. A recess  103   d  is positioned at the rear end of the surface  498   e ″ in the underside of the upper chassis  102  as shown in  FIG.  43   . That recess  103   d  provides sufficient clearance that the second pivot protrusion  502   b ″ can lift upwardly U ( FIG.  33   ) into the recess  103   d  away from the lower wall  498   e ′ of the second pivot cavity  502   c ″. At the same time, the first pivot protrusion  502   b ′ can lift upwardly U ( FIG.  37   ) to the top of the upper end of the front of the first pivot cavity  502   c ′. With that upward movement, the interlock features  103 ,  503  will engage with one another, so that the upper ends of the protrusions  503   a ,  503   b ,  503   c  contact and engage against the upper surfaces of the recesses  103   a ,  103   b ,  103   c , and those ends and surfaces transfer the loading of the apparatus to the handle  500 , instead of the pivot protrusions  502   b ′,  502   b ″ taking the load. In some configurations, the pivot protrusions  502   b ′,  502   b ″ will not take any of the load when the interlock features  103 ,  503  are engaged. In alternative configurations, the pivot protrusions  502   b ′,  502   b ″ will take some of the load when the interlock features  103 ,  503  are engaged. The engagement of the interlock features  103 ,  503  will inhibit rotation the handle  500  relative to the housing  100 , increasing the stability of the apparatus while it is being carried, and the likelihood of the apparatus tipping while being carried. The interlock features  103 ,  503  also reduce the torque a user must apply to keep the apparatus  10  substantially level whilst it is carried by the handle  500 . 
     When the apparatus  10  is rested back on a surface, the handle  500  and pivot protrusions  502   b ′,  502   b ″ will lower in the housing  100  under the weight of the handle  500 , so that the interlock features  103 ,  503  disengage from each other. The second pivot protrusion  502   b ″ moves down D ( FIG.  33   ) out of the recess  103   d , and the first pivot protrusion  502   b ′ moves down D ( FIG.  37   ) in the front of the first pivot cavity  503   c ′. After that movement, the handle can then be rotated to lower the handle to the lowered position of  FIGS.  30 ,  34 , and  38   . 
     It can be seen in the inset to  FIG.  33    that the projections  103   a ,  103   b ,  103   c  and the recesses  503   a ,  503   b ,  503   c  are provided with guide features to assist with engagement and/or disengagement of the projections  103   a ,  103   b ,  103   c  with the recesses  503   a ,  503   b ,  503   c . In the form shown, the recesses are slightly larger than the projections. Additionally, forward faces FF of the recesses and the projections are sloped or angled so as to be non-perpendicular to the top surfaces of the projections and recesses, to assist with engagement and disengagement of the interlock features. 
     The projections  503   a ,  503   b ,  503   c  may have substantially the same width (in a transverse direction of the apparatus) as the recesses  103   a ,  103   b ,  103   c  to provide improved stability when the projections and recesses are engaged. 
     As shown in  FIGS.  30  to  34   , the body portion  502   f  of the handle  500  comprises an additional interlock feature that is arranged to engage with the interlock feature of the housing when the handle is in the lowered position. In the form shown, the additional interlock feature comprises a projection  503   d  that has substantially the same form as the projections  503   a - d , and that engages in one of the recesses  103   a  when the handle is lowered ( 503   d ). That provides a positive engagement of the handle  500  and the housing  100  when the handle is lowered, reducing the likelihood of a user inadvertently lifting the handle  500  from the lowered position when the apparatus is in use. That also helps reduce the loading applied to the pivot protrusions  503   b ′,  503   b ″ if lateral force is applied to the handle  500  when the handle  500  is in the lowered position. The projection  503   d  may have substantially the same width (in a transverse direction of the apparatus) as the recess  103   a , to provide improved stability when the projection  503   d  and recess  103   a  are engaged. 
     The handle arrangement is configured to carry the full apparatus load including a liquid chamber  300  containing liquid. The handle may comprise honeycomb or rib feature(s) or fibre reinforcement to strengthen and stiffen the handle. The handle may be made from a suitable stiff and strong material. For example, the material may be a plastic material such as polycarbonate. The handle may have a hollow core and for example be produced by gas assist injection moulding. Where the handle has a substantially hollow core the handle may be devoid, or at least have a lesser amount, of honeycomb or rib feature(s). 
     In the form shown, the handle  500  is pivotally and translationally connected to the housing  100 . In an alternative configuration, the interlock features  103 ,  503  may be incorporated into a handle  500  that is only pivotally or only translationally connected to the housing  100 . 
     In the form shown, only one side of the handle  500  is movably connected to the housing. In an alternative configuration, two sides of the handle  500  may be movably connected to the housing  100 . The interlock features  103 ,  503  may be provided on one or both sides of the handle  500  and housing  100 . Two handle retainers  498  may be provided in the housing  100  to receive the two sides of the handle  500 . Alternatively, the two sides of the handle  500  may be directly movably connected to two sides of the housing  100 . 
     The interlock features  103 ,  503  may be provided on different surfaces from those shown. For example, instead of being provided on the body portion  502   f , the interlock features  503  could be provided on an upper surface of the arcuate portion  502   e  of the handle  500 , or could be provided elsewhere on the handle  500 . As another example, instead of being provided on the underside of the interconnecting wall  114  of the upper chassis  102 , the interlock features  503  could be provided elsewhere in the housing  100 . 
     The interlock features  103 ,  503  could have any suitable shape and configuration. For example, rather than having the shape shown, the projections  503  and recesses  103  could have an arcuate shape, or any suitable polygonal shape. The interlock features need not all have the same shape. 
     In the form shown, the first pivot protrusion  502   b ′ and first pivot cavity  502   c ′ are located toward an outer portion of the apparatus, and the second pivot protrusion  502   b ″ and the second pivot cavity  502   c ″ are located toward a centre of the apparatus. In an alternative configuration, the sides could be reversed. By having the pivot protrusions and pivot cavities on opposite sides of the handle, the handle mechanism is less likely to bind during movement of the handle  500 , particularly at the intersection between the first pivot cavity  502   c ′ and the second pivot cavity  502   c ″. Alternatively, the pivot protrusions  502   b ′,  502   b ″ and the pivot cavities  502   c ′,  502   c ″ could be provided on one side of the device (either towards the centre or the outer side), with a more rounded edge provided at the intersection between the first and second pivot cavities to reduce the likelihood of binding. 
     In the form shown, the interlock features  103 ,  503  are disengaged from each other when the handle  500  is in any one of a plurality of intermediate positions between the first, fully lowered position ( FIG.  2   ) and the second, fully raised position ( FIG.  29   ). That configuration means that there is a single raised position of the handle that is the optimum orientation of the handle  500  relative to the housing  100 , in which the interlock features will engage when the handle is used to carry the apparatus  10 . In alternative configurations, the interlock features  103 ,  503  may be engageable with each other when the handle  500  is in one or more of those intermediate positions, by applying upward force to the handle. The first and second pivot cavities  502   c ′,  502   c ″ may be modified to provide one or more additional regions into which the pivot protrusions  502   b ′,  502   b ″ can move to enable the handle  500  to be raised in those additional positions. When the interlock features  103 ,  503  comprise a plurality of members, a reduced number of the interlock feature members may be engageable when the handle  500  is in an intermediate position compared to when the handle  500  is in the second, fully raised position. 
     In the form shown, the first position in which the interlock features  103 ,  503  are engageable corresponds to a fully lowered position of the handle  500  ( FIG.  2   ), and the second position in which the interlock features  103 ,  503  are engageable corresponds to a fully raised position of the handle  500  ( FIG.  38   ). In alternative configurations, the first and/or second position are different position(s) that aren&#39;t the fully raised or fully lowered position. For example, one or both of the first and second positions could be an intermediate position between the lowered position and the raised position. As an example, the handle  500  may be moveable between the fully lowered and fully raised positions shown, but the second position in which the handle can be moved upward relative to the housing to engage the interlock features, may be in intermediate position that is close to, but short of, the fully raised position (for example, the position of the handle shown in  FIG.  28   ). That may be beneficial if the optimum carrying angle of the apparatus  10  is one in which the apparatus is tilted rearwardly, to minimise the likelihood of the liquid chamber  300  inadvertently being released from the liquid chamber bay  108  during carrying of the apparatus. As another example, the second position may be the raised position of the handle  500  shown in  FIG.  29   , but the handle may be configured such that when the apparatus is resting on a support surface, the handle can be moved further rearwardly than the position shown in  FIG.  29   , to provide greater clearance to access the liquid chamber  300 . Therefore, the first and/or second position may not be at the terminal ends of the path of travel of the handle  500  relative to the housing  100 . 
     A surface of the handle  500  bears against a surface of the handle retainer  4498  throughout movement of the handle from the fully lowered position to the fully raised position, to support the handle and prevent it from wobbling. For example, a left side face of the body portion  502   f  of the handle may bear against the left side wall of the handle retainer throughout that movement. Alternatively, a right side face of portions  502   e ,  502   f  of the handle may bear against the right side wall of the handle retainer throughout that movement. The surfaces that bear against each other are load-bearing and remain load-bearing throughout the movement of the handle. 
     The arcuate portion  502   e  and body portion  502   f  are wide to deal with bending moments through the single sided handle. The length of the base of the handle (between and extending beyond the pivot protrusions  502   b ′,  502   b ″) may be made as long as possible to reduce wobbling of the handle. 
     As shown in  FIG.  2   , when the handle  500  is in the fully lowered position, the handle is flush with the upper portion of the housing. That is, a substantially continuous surface is formed around the upper sides, front, and rear of the upper chassis  102  of the housing, including the handle  500 . 
     When forward/downward force is applied to the handle  500  to lower it from the fully raised position, the force is applied via the handle to the handle retainer  498  rather than directly to the upper or lower chassis. The force is not carried by the pivot protrusions in the pivot cavities. 
     In some configurations, the main housing and/or handle  500  may be provided with one or more magnets to retain the handle in the fully lowered and/or fully raised positions. For example, the handle may comprises magnet(s) and the housing may comprise magnet(s) or conductive component(s) that are attracted by the magnets, or vice versa.  FIG.  29    shows recesses  506 ′ in the underside of the handle  500  on or adjacent the cross-member  506 , and corresponding recesses  506 ″ in the upper chassis part  102  of the housing. Each recess may comprise a suitable magnet or conductive component. The apparatus may comprise one or more sensors, such as Hall Effect sensor(s) to determine whether the handle is in a lowered or raised position. 
     The magnets can provide a tactile and/or audible indication of engagement of the handle in the fully raised and/or lowered position. When using magnets, there is less likelihood of a liquid supply tube to the chamber being compressed and stopping liquid flow, as there may be with a mechanical latch (with which a liquid supply tube could potentially be captured between the handle and main housing and water flow cut off and/or the tube damaged). Magnets also have the benefit of reduced wear compared to a mechanical engagement feature. Magnets also enable the handle  500  to be released and raised from the lowered position using one hand, and mean that a latch such as a fingerbar or fingerguard is not required (which would require the use of two hands; one to bias a fingerguard downward, to allow for removal of the chamber and one to physically remove the chamber). 
     The single-sided handle  500  enables tube(s) that connect a liquid bag to the liquid chamber  300  to be fed through the space between the right side member  504  of the handle  500  and the main housing, when the handle  500  is in the raised (or an intermediate) position. 
     Instead of the pivot cavities  502   c ′,  502   c ″ being provided between the upper chassis part of the housing and the handle retainer  498 , the pivot cavities could instead be provided in the upper chassis part  102  or between the upper and lower chassis parts  102 ,  202  of the housing, and the handle retainer  498  not used. 
     This configuration is also suitable for use with a liquid chamber  300  that is filled from a liquid bag (or other liquid reservoir). 
     The handle  500  may comprise one or more features, such as apertures or hooks for example, for guiding liquid tube(s) from above into the liquid chamber  300 . The tube(s) will be coupled to the liquid chamber. The liquid chamber may comprise a float valve which controls flow of liquid from the tube(s) into the liquid chamber. 
     The handle  500  will be provided with one or more features to assist with insertion, retention, and/or removal of the liquid chamber  300  in or from the liquid chamber bay  108 , such as the engagement features  500   a ,  500   b ,  500   c  for example. 
     By providing a handle  500  that assists with insertion and/or retention and/or removal of the liquid chamber in and/or from the liquid chamber bay, a user can readily ensure that the liquid chamber  300  is fully inserted in the liquid chamber bay  108  while still being able to easily remove the liquid chamber from the liquid chamber bay when desired. This is particularly advantageous for users with limited mobility. The handle also avoids the use of a separate fingerguard. The liquid chamber bay may have detent(s) to assist with insertion and/or retention of the liquid chamber in the liquid chamber bay, such as those described above in relation to other configurations. Those details will enable a user to readily ensure that the liquid chamber is fully inserted in the liquid chamber bay. Full or correct insertion and/or retention may be required to ensure that a satisfactory seal is obtained and maintained between the liquid chamber and other component(s) that form part of the gasflow path. Because the handle encloses a portion of the liquid chamber bay when the handle is in the closed or fully lowered position, when the handle is in the fully raised position, a large space is created between the cross-member of the handle and the housing of the apparatus including a large opening at the front of the liquid chamber bay and around the liquid chamber, allowing easy insertion and removal of the liquid chamber to and from the liquid chamber bay because a user&#39;s fingers can easily fit between housing walls and the liquid chamber. 
     The handle  500  may be configured so that the liquid chamber  300  can be inserted into the liquid chamber bay  108  when the handle is in the raised position. When the handle  500  is in the lowered position, the handle will act as a chamber guard to both prevent the removal of the liquid chamber  300  from the liquid chamber bay  108 , and to prevent a user from touching the heater plate in the base of the liquid chamber. The handle may also minimise the likelihood of items being dropped into the liquid chamber bay  108  when the handle is in the lowered position. 
     Removal of the liquid chamber  300  from the liquid chamber bay  108  is a two-step procedure. First, the user lifts the handle  500  to the fully raised position. Second, the user removes the liquid chamber  300  from the liquid chamber bay  108 . Each of these steps can be done with a single hand, and the force required to perform each of the steps is low. This makes the apparatus particularly suitable for home use by a user who is unwell, and easier to use than an apparatus that requires two-handed operation to release a fingerguard. 
     Although the present disclosure has been described in terms of certain embodiments, other embodiments apparent to those of ordinary skill in the art also are within the scope of this disclosure. Thus, various changes and modifications may be made without departing from the spirit and scope of the disclosure. For instance, various components may be repositioned as desired. Features from any of the described embodiments may be combined with each other and/or an apparatus may comprise one, more, or all of the features of the above described embodiments. Moreover, not all of the features, aspects and advantages are necessarily required to practice the present disclosure. Accordingly, the scope of the present disclosure is intended to be defined only by the claims that follow. 
     The various configurations described are exemplary configurations only. For example, while the motor and/or sensor sub-assembly recess is described as being in the underside of the main housing, it could alternatively be in a rear, side, front, or top of the housing. With such a variant, the air and/or oxygen inlets may also be positioned differently as required. 
     As another example, rather than the liquid chamber and liquid chamber bay being configured so that the liquid chamber is inserted into and removed from the liquid chamber bay from a front of the housing, the configuration could be such that the liquid chamber is inserted into and removed from the liquid chamber bay from a side, rear, or top of the housing. 
     The features are described with reference to a flow therapy apparatus that is capable of delivering heated and humidified gases to a patient or user. The apparatus may be suitable for treating chronic obstructive pulmonary disease (COPD). The apparatus may be configured to deliver gases to a patient interface at a high flow rate (high flow therapy). 
     Alternatively, one, some, or all of the features may be provided in an apparatus for a different purpose. The apparatus may be a high flow therapy apparatus, or may be a low flow therapy apparatus. For example, the features may be provided in an apparatus for providing continuous positive airway pressure (CPAP), which may deliver gases (humidified or otherwise) at lower flow rates. 
     One or some of the features may alternatively be provided in an apparatus that does not require a humidifier and therefore does not require the liquid chamber  300  or liquid chamber bay  108  features. 
     The ‘flow therapy apparatus’ language is intended to cover all such variants. 
     Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world. 
     Where reference is used herein to directional terms such as “up”, “down”, “forward”, “rearward”, “horizontal”, “vertical” etc, those terms refer to when the apparatus is in a typical in-use position, and are used to show and/or describe relative directions or orientations.