Abstract:
An oil separator for use in a vehicle air system includes a recycling valve for removing coalesced oil. The recycling valve may include a piston movable in a cylinder in response to a control air pressure to open the recycling valve and thus drain coalesced oil from a sump under the influence of residual air pressure in the sump. The separator may include a fixture for mounting the separator to a vehicle, including a plurality of ports extending from an inlet port for directing air into the cartridge with a combined flow area at least equal to the flow area of the inlet port. The plurality of ports preferably extend at a right angle to the direction of flow of air through the inlet port. A safety relief valve on the separator releases air when the pressure exceeds a predetermined pressure.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a vehicle air system and specifically to an oil separator for removing oil from compressed air used in the system. 
   BACKGROUND OF THE INVENTION 
   An oil separator is conventionally used with vehicle compressed air systems to clean contaminants, such as lubricating oil, from the air pumped from the compressor. An oil separator may significantly restrict the flow of air through the air brake system if it becomes clogged with carbon from the oil in the compressed air. Restricting the flow of air causes significant back pressure which can cause damage to the compressor. 
   In addition, the air brake system typically includes an air dryer downstream of the compressor, with a replaceable cartridge. The lifespan of the air dryer cartridge is determined in large measure by how much oil is entrained in the air delivered to the air dryer. Too much oil, or even small amounts of oil, inside the air dryer will negatively affect the performance of the air dryer and increase the frequency of the maintenance service required on the air dryer. The separator preferably removes as much oil as possible from the air in the system. Oil that is removed from the system is typically dumped or wasted, which can be costly and environmentally damaging. 
   SUMMARY OF THE INVENTION 
   In one aspect the present invention relates to an oil separator for use in a vehicle air system. The separator includes a fixture for mounting the oil separator to a vehicle, an oil separator cartridge attached to the fixture for coalescing oil in air supplied to the oil separator, and a recycling valve for removing coalesced oil from the oil separator. The recycling valve may include a piston movable in a cylinder in response to a control air pressure to open the recycling valve. The recycling valve may include an inlet port in fluid communication with the cartridge through a sump and also an outlet port. The piston may be movable in response to a control air pressure from the closed position to an open position enabling fluid to flow out of the sump through the inlet port and the outlet port. 
   In another aspect the invention relates to a method including the steps of directing compressed air into a cartridge of an oil separator to coalesce oil in the compressed air, collecting the coalesced oil in a sump attached to the oil separator, and opening a recycling valve attached to the sump to enable coalesced oil to flow out of the sump. The method may also include the step of forcing the coalesced oil to flow out of the sump through the recycling valve under air pressure from the sump. 
   In a further aspect, the present invention relates to an oil separator for use in a vehicle air system, including a fixture for mounting the oil separator to a vehicle, and an oil separator cartridge attached to the fixture for coalescing oil in air supplied to the oil separator. The fixture includes an inlet port for allowing air from a compressor into the fixture and a delivery port for allowing air to exit the oil separator after being cleaned. The fixture also includes a plurality of ports extending from the inlet port for directing air from the inlet port into the cartridge. The plurality of ports have a combined flow area at least equal to the flow area of the inlet port. The plurality of ports preferably extend at a right angle to the direction of flow of air through the inlet port. The fixture may be made from a single piece of metal. 
   In a further aspect, the present invention relates to an oil separator for use in a vehicle air system, including a fixture for mounting the separator to a vehicle, an inlet port for allowing air from a compressor into said fixture, and a delivery port for allowing air to exit said oil separator after being cleaned. The fixture includes a pressure relief valve in fluid communication with the inlet port for releasing air from the oil separator in response to air pressure reaching a predetermined amount. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which: 
       FIG. 1  is a schematic illustration of a vehicle braking system including an oil separator in accordance with the present invention. 
       FIG. 2  is a perspective view of the oil separator of  FIG. 1 ; 
       FIG. 3  is another perspective view of the oil separator of  FIG. 1 ; 
       FIG. 4  is a sectional view of parts of the oil separator of  FIG. 1  showing an inlet flow path to a cartridge that forms part of the oil separator; 
       FIG. 5  is a sectional view similar to  FIG. 4  showing an outlet flow path from the cartridge; 
       FIG. 6  is a sectional view similar to  FIG. 4  showing an outlet flow path from a sump that forms part of the oil separator; 
       FIG. 7  is a sectional view through a recycling valve that forms part of the oil separator; 
       FIG. 8  is a sectional view similar to  FIG. 7  showing parts of the recycling valve in an open condition; 
       FIG. 9  is a perspective view of an oil separator constructed in accordance with a second embodiment of the invention; 
       FIG. 10  is a perspective view of a fixture that forms part of the oil separator of  FIG. 9 ; and 
       FIG. 11  is a sectional view taken generally along line  11 - 11  of  FIG. 10 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention relates to a vehicle air system and specifically to an oil separator for removing oil from compressed air used in the system. The present invention is applicable to oil separators of varying constructions. As representative of the invention,  FIG. 1  illustrates an oil separator  10  constructed in accordance with a first embodiment of the invention. 
   The separator  10  forms part of a vehicle air braking system  12 . The vehicle braking system  12  also includes a compressor  14 . The compressor  14  supplies air to the separator  10  through an air line  16 . Clean air from the separator  10  flows to an air dryer  18  through another air line  20 . Dry air from the dryer  18  flows to the vehicle brakes (and other accessories) through an outlet fitting  22  on the air dryer. Another air line  24  from the compressor  14  is connected with a recycling valve  30  on the separator  10 , to supply a control signal as described below. The system  12  also includes a return oil line  32  extending from the recycling valve  30 . 
   The oil separator  10  ( FIG. 2 ) includes a housing or fixture  40  and a cartridge  42 . The fixture  40  is preferably machined from a single block of aluminum, although it could be made in another manner and from another material. The fixture  40  has grooves  44  on two opposing sides for securing the separator  10  on the vehicle. The fixture  40  has a threaded post  46  ( FIG. 4 ) on a top surface  48  for connecting with the cartridge  42 . The connection allows the cartridge  42  to rest or stand on the top surface  48  of the fixture  40  after being assembled to the fixture. The thread design for the threaded post  46  is specific to the attaching means of the cartridge  42 . 
   The fixture  40  ( FIG. 4 ) includes a supply or inlet port  50  and a delivery or outlet port  52  ( FIG. 5 ). The inlet port  50  receives pressurized air from the compressor  14 . The inlet port  50  is connected internally in the fixture  40  by a cross-passage  53  with at least two internal ports  54 . Preferably more than two of the ports  54  are provided, for example six to twelve ports. The ports  54  extend at right angles to the direction of air flow through the inlet port  50  and the cross passage  53 , and connect the inlet port with the cartridge  42 . 
   In the embodiment shown in  FIGS. 1-7 , the fixture  40  includes an exit passage  56  ( FIG. 5  that extends through the threaded post  46 . The exit passage  56  is in fluid communication with the interior of the cartridge  42 . In the preferred embodiment, the exit passage  56  branches into at least two exit channels  58 . 
   A threaded post  60  is provided on a bottom surface  62  of the fixture  40 . The post  60  may be similar in configuration to the threaded post  46  on the top surface  48  of the fixture  40 . A sump  70  is screwed on the post  60 . The exit channels  58  communicate with the sump  70 . The sump  70  has an exit passage  72  that extends through the threaded post  60  on the bottom surface  62  of the fixture  40 . The exit passage  72  is connected to the delivery port  52 . 
   In operation of the separator  10 , compressed air is pumped to the separator from the compressor  14 . Before entering the cartridge  42 , the air flows through the inlet port  50  of the fixture  40 . The flow of air branches off into the at least two inlet ports  54 . 
   The size and number of the inlet ports  54  is selected to achieve a flow area that is equal to the flow area of the inlet port  50 . The multiple inlet ports  54  to the cartridge  42  provide a free flow path for air coming from the compressor  14 , thus reducing back pressure. This reduction in back pressure can increase the life and reliability of the compressor  14 . 
   The flowing air must make at least one right angle turn from the inlet port  50  to move into the inlet ports  54 . This re-direction of the air flow slows the air flow and creates turbulence. The multiple inlet ports  54  also help to disperse the oil throughout the cartridge  42 . All these factors help to cause any oil that is entrained in the air to coalesce into droplets, and produce a better cleaning effect. 
   As the air flows through the cartridge  42 , oil is separated from the air, condensing into large oil droplets. The exit passage  56  receives compressed air and oil droplets from the cartridge  42 . The air and condensed oil flow through the passages  58  into the sump  70 . The oil droplets are deposited and accumulated in the sump  70 , mainly due to gravity. 
   The cleaned air exits from the sump  70  through its exit passage  72 . The exit passage  72  is connected to the delivery port  52  which delivers the filtered compressed air downstream to the air dryer  18  ( FIG. 1 ) through the air line  20 . 
   Accumulated oil is periodically removed from the sump by the recycling valve  30 . The recycling valve  30  ( FIGS. 7 and 8 ) includes a housing  74 . A cylinder  76  in the housing  74  supports a piston  78  for reciprocal sliding movement in the housing. The piston  78  is biased to a closed position ( FIG. 7 ) in the cylinder by a spring or other biasing means  80 . O-rings  82  on the piston  78  prevent leakage of oil and pressurized air past the piston to atmosphere. 
   The housing  74  of the recycling valve  30  includes an inlet port  84  that communicates with the sump  70 . The inlet port  84  may be formed in differing manners and in the illustrated embodiment is formed in a hollow threaded post  86  that connects with an exit port of the sump  70 . The housing  74  also includes an outlet port  90  for directing oil out of the recycling valve  30  and returning it to the engine or to the compressor  14 . The outlet port  90  is located adjacent the inlet port  84 . 
   In addition, the recycling valve  30  has a control port  92 . The control port  92  is in fluid communication with the cylinder  76  within the recycling valve  30 . The control port  92  is connected to a delivery port  94  ( FIG. 1 ) of a governor  96  of the compressor  14 . The control port  92  is effective to receive control air under pressure. The governor  96  monitors pressure downstream from the compressor  14 . 
   When the valve  30  is in the closed condition shown in  FIG. 7 , a portion  98  of the piston  78  blocks fluid communication between the inlet port  84  and the outlet port  90 . Oil that is accumulated in the sump  70  therefore remains in the sump. 
   The valve  30  may be actuated when the compressor  14  is unloaded, or at other preselected or predetermined times. Thus, in the preferred embodiment, if the pressure downstream of the oil separator  10  reaches a preset value, the compressor  14  unloads (stops sending air to the separator). As a result, a suitable control signal (control pressure) is applied to the control port  92 . The piston  78  moves from the closed position shown in  FIG. 7  to the open position shown in  FIG. 8 , against the bias of the spring  80 . Fluid communication between the inlet port  84  and the outlet port  90  is established. 
   Oil from the sump  70  is free to flow out of the sump through the recycling valve  30 . The residual air pressure in the sump  70  forces the oil to flow out through the valve  30  and return to the engine or compressor  14  of the vehicle, thus preventing waste and environmental damage. After a brief period of time, the pressure in the sump  70  diminishes, the control signal at the control port  92  is removed, and the recycling valve  30  closes. 
     FIGS. 9-11  illustrate an alternative embodiment in which the fixture  40  is not connected to a sump. In this embodiment, the exit passage  56  through the threaded post  46  on the top surface  48  of the fixture  40  is connected to the delivery port  52 . With this embodiment, another means for collecting the oil condensed into droplets must be provided, instead of the sump  70  and the recycling valve  30 . This alternative means would be located between the delivery port  52  of the housing fixture  40  and the air dryer  18 . 
   In accordance with another feature of the invention, a pressure relief valve  55  ( FIGS. 2-4 ) is provided for the oil separator  10 . The pressure relief valve  55  may be located at any point in the air flow path between the compressor  14  and the oil separator  10 , and does not have to be directly attached to or form a part of the separator itself. 
   In the illustrated embodiment, the relief valve  55  is mounted on the fixture  40  of the separator  10 . The relief valve  55  may be a commercially available pressure relief valve. A first end or inlet end  57  of the relief valve  55  is in fluid communication with the supply port  50  via the cross passage  53 . A second end or outlet end  59  of the relief valve  55  projects outward of the fixture  10  to atmosphere. A normally closed air flow passage  61  extend between the inlet end  57  and the outlet end  59 . 
   The pressure relief valve  55  is set to be activated when the supply pressure to the separator  10  as sensed at the relief valve equals or exceeds a predetermined level or set value. The predetermined level is based on a variety of factors. These factors include, but are not necessarily limited to, the maximum working pressure of the compressor, the volume of flow, the rating of connecting hoses or lines, and the rating of the cartridge  42 . The predetermined value is set during manufacturing and, because the relief valve  55  as installed is tamper resistant, the set value cannot be changed. The predetermined value may be 225 psi, for example, 
   If the supply port  50  or one or more of the passages  54  or the cartridge  42  becomes partially or completely clogged with carbon from the oil in the air, the oil separator is not able to accept the amount of air pumped out from the compressor  60 . Air pressure builds up at the supply port  50 . If the air pressure reaches the predetermined maximum level, the pressure relief valve  55  is activated, allowing air to flow out of the fixture  40  to atmosphere. This action releases the excessive pressure that might otherwise cause damage to the compressor  14  and other upstream components. 
   The exiting of the compressed air through the pressure relief valve  55  creates an audible indication to the operator that the supply pressure is greater than the delivery pressure and that as a result the braking system might not function properly. In an alternative embodiment, the relief valve  55  may provide a warning signal that is electrical, for example, visually signaling the operator with a light, such as an LED, that a problem has occurred. 
   Although the invention has been described in detail with reference to certain preferred embodiments, other embodiments are possible. For example, the separator is usable in an air system other than a braking system. Therefore, the spirit and scope of the appended claims should not be limited to the description of the described embodiments.