Abstract:
In an apparatus for distributing air flowing along a first path, the first path splits into second and third paths, so that both the second and third paths diverge from the first path. The second and third paths are at an angle of less than 180° to one another. A first door, is across the second path; and a second door, is across the third path. A common operating device rotates both doors, such that air is able to flow from the first path into the second and third paths, the flow being dependent on the position of rotation of the doors.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus for distributing air, to an apparatus for controllably rotating first and second doors simultaneously usable in such apparatus, and to a vehicle air conditioning system. 
     BACKGROUND OF THE INVENTION 
     Vehicle air conditioning systems commonly have a number of outlet vents along the dashboard for example two face-level vents close to the vehicle centre line, and two further face-level vents situated close to the doors. One known apparatus has a fan propelling air through an evaporator into a mixing chamber where the air cooled by the evaporator mixes with air heated in a heater core. A flow control door is disposed across an outlet region of the mixing chamber, so that when the door is opened, air is provided at the previously-discussed face-level vents. 
     The known air conditioning apparatus is approximately along the vehicle centre line with air flow in the fore-and-aft direction, and the air outlet at the flow control door impinges on a transverse wall in an outlet chamber having two transverse outlets leading to the above-mentioned further vents, and two spaced aft-facing outlets for the centre-line face vents. 
     As a result, the fore-and-aft flow direction in the air conditioning apparatus sharply alters to two opposed generally transverse flows in the outlet chamber, with yet a further sharp turn to the fore-and-aft direction for the centre-line face vents. 
     As is known to those skilled in the art, such flow direction deviations waste energy, thus causing pressure drops, which means that an increased power of fan is needed to provide adequate flow. The movement of air due to such a fan, when incident on a wall transverse to the flow direction is undesirably noisy. 
     A primary object of the invention is to at least partly overcome the problems of the prior art. 
     It would be desirable to provide an improved apparatus for dividing a gas flow, such as an air flow, in a single path into two paths. It would further be desirable to provide a vehicle heating or air-conditioning system incorporating such apparatus having limited space, particularly in the direction of flow in the single path, which would mitigate drawbacks of noise, heat loss and excessive pressure drop. It would also be advantageous for such an improved apparatus to be extended to divide each of the two paths into two further paths. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the present invention there is provided apparatus for distributing air, said air flowing along a first path, the apparatus comprising: 
     walls defining said first, a second and a third path, the first path bifurcating into the second and third paths, both the second and third paths diverging from the first path and having respective portions disposed at an angle of less than 180° to one another; 
     a first door, rotatable about an axis disposed across the said portion of the second path; 
     a second door, rotatable about an axis disposed across the said portion of the third path; 
     a common operating device for rotating both doors, such that air is able to flow from the first path into the second and third paths, the flow being dependent on the position of rotation of the doors. 
     In such an apparatus the common operating device may comprise: 
     a shaft having a longitudinal axis, the shaft being rotatable about said longitudinal axis; 
     an actuator for rotating said shaft; 
     a first arm extending from the said shaft for rotation therewith, the first arm having a distal end; 
     a first linkage having two ends, one end being connected via a first joint to said distal end of said first arm, the first joint permitting relative rotation in two orthogonal planes between said first linkage and said first arm, and the other end being connected via a second joint to the first door, the second joint permitting relative rotation in two orthogonal planes between said first linkage and said first door; and the apparatus further comprising: 
     a second arm extending from the said shaft for rotation therewith, the second arm having a distal end; 
     a second linkage having two ends, one end being connected via a third joint to said distal end of said second arm, the third joint permitting relative rotation in two orthogonal planes between said second linkage and said second arm, and the other end being connected via a fourth joint to the second door, the fourth joint permitting relative rotation in two orthogonal planes between said second linkage and said second door. 
     Preferably the joints within the single operating device comprise either a ball and socket joint or alternatively a part having an aperture, and a hook which is hooked into the aperture. 
     Conveniently a heater core is disposed in the said first path, whereby air in the said second and third paths would be heatable. 
     According to a second aspect of the present invention, there is provided an apparatus for controllably rotating a first and a second door simultaneously, comprising: 
     a shaft having a longitudinal axis, the shaft being rotatable about said longitudinal axis; 
     an actuator for rotating said shaft; 
     a first arm extending from the said shaft for rotation therewith, the first arm having a distal end; 
     a first linkage having two ends, one end being connected via a first joint to said distal end of said first arm, the first joint permitting relative rotation in two orthogonal planes between said first linkage and said first arm, and the other end being connected via a second joint to the first door, the second joint permitting relative rotation in two orthogonal planes between said first linkage and said first door; and the apparatus further comprising: 
     a second arm extending from the said shaft for rotation therewith, the second arm having a distal end; 
     a second linkage having two ends, one end being connected via a third joint to said distal end of said second arm, the third joint permitting relative rotation in two orthogonal planes between said second linkage and said second arm, and the other end being connected via a fourth joint to the second door, the fourth joint permitting relative rotation in two orthogonal planes between said second linkage and said second door. 
     Conveniently the first and second doors each have a respective axis of rotation, said axes being disposed at an angle of between 0° and 180° to one another. 
     Preferably the joints comprise either a ball and socket joint or alternatively a part having an aperture, and a hook which is hooked into the aperture. 
     According to a third aspect of the present invention, there is provided a vehicle air-conditioning system comprising: 
     walls defining a first, a second and a third path, the first path bifurcating into the second and third paths, both the second and third paths diverging from the first path and having respective portions disposed at an angle of less than 180° to one another; 
     an evaporator disposed in the first path; 
     a heater core disposed in the first path downstream of the evaporator; 
     a first door, rotatable about an axis disposed across the said portion of the second path; 
     walls defining fourth and fifth paths, wherein the second path bifurcates into the fourth and fifth paths, the fourth path being offset from the first path and aligned substantially parallel to it, wherein air is able to flow from the second path into the fourth and fifth paths and out into the vehicle interior, flow being dependent on the position of rotation of the first door; 
     a second door, rotatable about an axis disposed across the said portion of the third path; 
     walls defining sixth and seventh paths, wherein the third path bifurcates into the sixth and seventh paths, the sixth path being offset from the first path and aligned substantially parallel to it, wherein air is able to flow from the third path into the sixth and seventh paths and out into the vehicle interior, flow being dependent on the position of rotation of the second door. 
     Conveniently the fifth and seventh paths are disposed substantially perpendicular to the first path and at substantially 180° to one another. 
     Advantageously a common operating device is provided for rotating both doors. Such an operating device suitably comprises: 
     a shaft having a longitudinal axis, the shaft being rotatable about said longitudinal axis; 
     an actuator for rotating said shaft; 
     a first arm extending from the said shaft for rotation therewith, the first arm having a distal end; 
     a first linkage having two ends, one end being connected via a first joint to said distal end of said first arm, the first joint permitting relative rotation in two orthogonal planes between said first linkage and said first arm, and the other end being connected via a second joint to the first door, the second joint permitting relative rotation in two orthogonal planes between said first linkage and said first door; and the apparatus further comprising: 
     a second arm extending from the said shaft for rotation therewith, the second arm having a distal end; 
     a second linkage having two ends, one end being connected via a third joint to said distal end of said second arm, the third joint permitting relative rotation in two orthogonal planes between said second linkage and said second arm, and the other end being connected via a fourth joint to the second door, the fourth joint permitting relative rotation in two orthogonal planes between said second linkage and said second door. 
     Preferably the joints comprise either a ball and socket joint or alternatively a part having an aperture, and a hook which is hooked into the aperture. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the invention, reference will now be made to the accompanying drawings, in which: 
     FIG. 1 shows a partial cross-sectional view through a vehicle air-conditioning system according to the prior art, which divides a single air path into two paths and further divides each of these two paths. 
     FIG. 2 shows a front view of an exemplary arrangement of face-level outlets for a vehicle air-conditioning system. 
     FIG. 3 shows a partial cross-sectional view through a vehicle air-conditioning system incorporating a preferred embodiment of the present invention. 
     FIG. 4 shows a perspective view of a door control device used in the system of FIG.  3 . 
     FIG. 5 shows a ball and socket joint for use in the apparatus of FIG.  4 . 
     FIG. 6 shows an alternative joint for use in the apparatus of FIG.  4 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the figures, like reference numerals indicate like parts. 
     Referring to FIG. 1, a vehicle air-conditioning system has an air inlet duct  2 , leading to a first flow path  8  defined by walls  4  and  6  which house an evaporator  22  and a heater core  24 . The first flow path is terminated by an end wall  38  and divides into a transverse left path  10  and a transverse right path  12 . The left path  10  further divides into a left side path  14  formed from a rear wall  13  and a front wall  15 , which is disposed at right-angles to flow path  8 , and a left centre path  16 , formed form a left wall  17  and a right wall  19 , which is disposed parallel to first flow path  8  but laterally offset. Similarly the right path  12  further divides into a right side path  18  formed from a rear wall  21  and a front wall  23 , which is disposed at right-angles to flow path  8 , and a right centre path  20  formed from a left wall  25  and a right wall  27 , which is disposed parallel to flow path  8  but laterally offset. Paths  14  and  18  are disposed at 180° to one another. A flow control door  26  is disposed downstream of the heater core  24  in the first flow path  8 . The door is rotatable about its centre axis  28  by means of an actuator  30 , between an open position as shown in FIG. 1, and a closed position. 
     In operation, air enters through inlet duct  2  in the direction of arrow  32  and passes through the device until incident upon the end wall  38 . It then divides into two portions as indicated by arrows  34  and  36 . A first portion follows the direction of arrow  34  into the left path  10  and a second portion follows the direction of arrow  36  into the right path  12 . It can be seen that the shape of the left-hand corner  37  and the right-hand corner  39  just downstream of the door force both portions of air to make right-angular turns in order to flow into paths  10  and  12 . The air flow is further affected by end wall  38  which is situated only a short distance from door  26 . Air incident upon the end wall  38  results in impact noise and heat loss. The combination of features of path shape also results in excessive pressure drop. 
     Referring additionally to FIG. 2, because left path  10  further divides, the first portion of air is then further divided into a third portion which flows along path  14  from where it flows out into a left-hand side outlet  40  in the vehicle interior, and a fourth portion which makes a further right-angled turn to flow into path  16  from where it flows out into a left-hand centre outlet  42  in the vehicle interior. Similarly, because right path  12  further divides, the second portion of air is then further divided into a fifth portion which flows along path  18  from where it flows out into a right-hand side outlet  46  in the vehicle interior, and a sixth portion which must make a further right-angled turn to flow into path  20  from where it flows out into a right-hand centre outlet  44  in the vehicle interior. These two further right-angled turns result in yet more pressure drop. 
     Referring now to FIG. 3, an air-conditioning system incorporating the present invention provides relatively gentle transitions in flow direction. There is provided an air inlet duct  2 , leading to a first flow path  8  defined by walls  4  and  6  which house an evaporator  22  and a heater core  24 . The first flow path divides into a transverse left path  110  and a transverse right path  112  and is terminated by an end wall  138 . The first flow path extends into the transverse left path  110  and transverse right path  112  which are disposed at approximately 45° to first flow path  8 , and at approximately 90° to one another. This is achieved by corner portion  137  which extends from wall  4 , and wall  150 , which together define path  110 , and corner portion  139  which extends from wall  6 , and  152 , which together define path  112 . Corner portions  137  and  139  are gently curved in shape. Walls  150  and  152  are connected at their upstream ends by end wall  138 . 
     The left path  110  further divides into a left side path  14  defined by a rear wall  13  and a front wall  15 , which is disposed at right-angles to flow path  8 , and a left centre path  16 , defined by a left wall  17  and a right wall  19 , which is disposed parallel to first flow path  8  but laterally offset. Wall  150  extends at its downstream end into wall  19 . 
     Similarly the right path  12  further divides into a right side path  18  defined by a rear wall  21  and a front wall  23 , which is disposed at right-angles to flow path  8 , and a right centre path  20  defined by a left wall  25  and a right wall  27 , which is disposed parallel to flow path  8  but laterally offset. Wall  152  extends at its downstream end into wall  25 . Paths  14  and  18  are disposed at 180° to one another. 
     There are provided a first flow control door  154 , which is rotatable about its centre axis  158 , and a second flow control door  156  which is rotatable about its centre axis  160 . The centre axis  158  of the first door is disposed across the path  110  which is disposed at approximately 45° to first flow path  8  and the centre axis  160  of the second flow door is disposed across the path  112  which is disposed at approximately 45° to first flow path  8 . Both doors are rotatable between an open position as shown in FIG. 3, and a closed position. There is provided a common actuator  130  for rotating both doors. 
     In operation, air enters through inlet duct  2  in the direction of arrow  32  and passes through the device until it reaches the first and second flow control doors  154 ,  156 . It then divides into two portions as indicated by arrows  134  and  136 . A first portion follows the direction of arrow  134  into the left path  110  and a second portion follows the direction of arrow  136  into the right path  112 . Air hitting end wall  138 , will be divided from there to follow the flow paths indicated by either arrow  134  or  136 . It can be seen that the shape of the left-hand corner portion  137  and the right-hand corner portion  139  allow both portions of air to make gentle 45° turns in order to flow into paths  110  and  112 . 
     Referring additionally to FIG. 2, as left path  110  further divides, the first portion of air is then further divided into a third portion which makes a further gentle 45° turn to flow along path  14  from where it flows out into a left-hand side outlet  40  in the vehicle interior, and a fourth portion which makes a further gentle 45° turn to flow into path  16  from where it flows out into a left-hand centre outlet  42  in the vehicle interior. Similarly, as right path  112  further divides, the second portion of air is then further divided into a fifth portion which makes a further gentle 45° turn to flow along path  18  from where it flows out into a right-hand side outlet  46  in the vehicle interior, and a sixth portion which makes a further gentle 45° turn to flow into path  20  from where it flows out into a right-hand centre outlet  44  in the vehicle interior. These further 45° turns, coupled with the fact that only a small portion of the air impinges on end wall  138 , reduce pressure drop, heat loss and noise. A further advantage of the arrangement is that its total length in the direction of first flow path  8  is small enough for use within a vehicle air-conditioning system. 
     It is advantageous to have a common actuator  130  for the two doors because, among other things, during installation or maintenance, it is easier to install or access a single actuator in one location, rather than having to install or access two actuators in two separate locations within the vehicle. A single actuator is also more economical to manufacture and assemble than two separate actuators. 
     Referring now to FIG. 4, actuator  130  provides a mechanism for operating both flow doors  154  and  156  simultaneously. So as to present the most useful view, FIG. 4 is a perspective view looking downstream and from above (out of page) FIG.  3 . Therefore, door  154  is the right-hand door and door  156  is the left-hand door in FIG.  4 . The mechanism comprises a shaft  162 , which has two arms  164 ,  166  fixedly attached to it. It would also be possible for the shaft and these arms to be formed from a common piece of material. Arm  164  is connected via joint  172  to linkage  168 . Linkage  168  is attached to door  154  via joint  176 . Considering door  154  to be divided into an upstream half and a downstream half by its centre axis  158 , the attachment point of door  154  is approximately in the centre of the upstream half  180  of the door, on the upper surface which is visible in FIG.  3 . In this embodiment, the joints  172 ,  176  are ball and socket joints. 
     Similarly, arm  166  is connected via joint  174  to linkage  170 . Linkage  170  is attached to door  156  via joint  178 . Considering door  156  to be divided into an upstream half and a downstream half by its centre axis  160 , the attachment point of door  156  is approximately in the centre of the upstream half  182  of the door, on the upper surface which is visible in FIG.  3 . In this first embodiment, the joints  174 ,  178  are ball and socket joints. 
     The actuator  130  is contained within a housing in the vehicle, but this is omitted from FIG. 4 in the interest of clarity. 
     As shown in FIG. 4, doors  154 ,  156  are in the same position as in FIG. 3, that is they are in an open position which allows air to flow past them. In operation, a dashboard control (not shown) operates a connector  184  in a manner known to those skilled in the art, for example with a Bowden cable. The connector  184  rotates the shaft  162  in the direction indicated by arrow  186 , which is anti-clockwise in the figure. As shaft  162  rotates, arms  164 ,  166  rotate with it. This applies motion to linkages  168  and  170  respectively via ball and socket joints  172 ,  174 . Bearing in mind that the doors  154 ,  156  are constrained on fixed axes, they are only able to rotate about these axes in an anti-clockwise direction as shown by arrows  188 ,  190  respectively. Due to motion imparted through linkages  168 ,  170 , they are able to rotate sufficiently to close paths  110 ,  112  to air flow. Due to the angles of the doors relative to the shaft, the linkages  168 ,  170  undergo a three-dimensional movement during the rotation of the doors. This is made possible by the joints  172 ,  174  allowing two-dimensional motion in the y-z plane, whilst joints  176 ,  178  allow two-dimensional motion in the plane of the door. 
     A detail of linkage  168  and joints  172 ,  176  is shown in FIG.  5 . This shows how arm  164  provides the “socket” in order to constrain joint  172  in the direction of rotation of the shaft and how extension  192  to door  154  also provides a socket to constrain joint  176  in the plane of the door. In order for the necessary motion to be transmitted through linkage  168 , it is important that the linkage  168  is held in a fixed position relative to arm  164  whilst still being able to rotate and similarly that the linkage  168  is held in a fixed position on door  154  whilst still being able to rotate. The arm  164  constrains the linkage  168  in a vertical direction in FIGS. 4 and 5 because this is the direction in which the linkage  168  would otherwise move relative to the arm  164 . Similarly, the extension  192  prevents the linkage  168  from sliding on the surface of the door  154 . 
     The other linkage  170  works in a similar way with joints  174 ,  178  during rotation of door  156 . 
     In an alternative apparatus, the linkages  168 ,  170  and joints  172 ,  174 ,  176  and  178  are replaced by hook and eye joints. FIG. 6 shows a detail of linkage  268  which used in place of linkage  168 , along with its associated joints. This linkage  268  is attached with hook and eye joint  196 , which replaces ball and socket joint  172 , and by hook and eye joint  198 , which replaces ball and socket joint  176 . Joint  196  has an eye  200  provided by a modified arm  264 , this arm  264  being used in place of arm  164 . The linkage  268  has a hook  204  at the end for connection to arm  264 , which hooks into eye  200 . Extension  192  on door  154  is replaced by extension  292 , comprising an eye  202 . The linkage  268  has a hook  206  which hooks into eye  202 , thus connecting the linkage  268  with door  154 . 
     In operation, the joints  196 ,  198  work in a similar way to joints  172 ,  176 , allowing linkage  268  to transmit motion to rotate door  154  through three-dimensional movement, by allowing two-dimensional movement of each joint. The joints are constrained relative to arm  264  and door  154  as before. A similar arrangement of hook and eye joints is provided for imparting motion between shaft  162  and door  156 . An advantage of this alternative apparatus is that it is especially economical to manufacture and assemble. 
     It would of course be possible to use other types of joints in place of the joints described above. An example of a different type of joint which would work is a universal joint. The invention is not limited to using one of the mentioned joints. 
     It would also be possible to use a joint which only allowed one-dimensional movement in place of the joints for attachment to the arms  164 ,  166 , if these arms were capable of sliding along shaft  162 , such that the sliding movement would allow the necessary motion in the second dimension. A further possible method of transmitting motion from the shaft to the doors would be to use elastic members which were fixedly attached to the shaft and the doors, which would be capable of deforming in three dimensions, but this might not provide the necessary durability for the lifetime of the vehicle. 
     Any of the described apparatus including the alternatives mentioned above could be used in a heating only system, in which case the evaporator  22  would not be required. 
     It would be possible to use the described embodiment and alternatives in a dual-zone system. In this case, the left side paths would be used to supply air to one zone and the right side paths would be used to supply air to the second zone. Under these circumstances it would be necessary to replace actuator  130  with two separate actuators, so that flow to the two zones could be allowed independently. Use of this apparatus would provide the advantage of a gentle flow path.