Patent Publication Number: US-2022213789-A1

Title: Compressed air driven motor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U. S. application Ser. No. 16/962, 081 filed Jul. 14, 2020 and entitled “COMPRESSED AIR DRIVEN MOTOR, ” which in turn is a national stage filing of International PCT Application No. PCT/US2019/13173 filed Jan. 11, 2019 for “COMPRESSED AIR DRIVEN MOTOR, ” which in turn claims the benefit of U. S. Provisional Application No. 62/617,406 filed Jan. 15, 2018, and entitled “COMPRESSED AIR DRIVEN MOTOR, ” the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     This disclosure relates generally to air motors. More specifically, this disclosure relates to control and poppet valves for an air driven motor. 
     Pneumatic motors are driven by the expansion of compressed air, typically by either a linear motion or a rotary motion. With linear motion, the compressed air drives a diaphragm or piston actuator disposed within the air motor. The compressed air is directed to both sides of the actuator to create an upstroke and a downstroke. The change of air flow to the piston is controlled by an air motor control valve and, in most examples, two poppet valves. Air motors can be used to drive various components. For example, an air motor can be used to drive one or more pumps, such as pumps for a spraying system. 
     Air motors are prone to icing, especially near the exhaust and the poppet valves. Further, icing is prone to form on the cylinder sleeve and adjacent cylinder housing of the air motor as those components cool. Icing is a result of the Venturi effect. Ice will form adjacent to a pressure drop (in accordance with the Venturi effect and the Ideal Gas Law), such as near the compressed air leaving a poppet valve or the air motor exhaust. When compressed air driven motors release a large amount of compressed air, the pressure and temperature of the air drops suddenly with a spike in velocity and drop in pressure as the compressed air expands. This sudden temperature drop causes water vapor in the air to change from gas to liquid, and quickly freeze on anything the water vapor contacts. Because of the large temperature drop, icing in an air motor frequently occurs at ambient environmental temperatures well above freezing. The housing of the air motor will eventually cool after extended operation as a result of the cooled air flowing within and/or near the housing, leading to ice accumulation where the cooled air contacts the housing and/or the other air motor components. Ice accumulation in the air motor is most predominate when the exhausted air immediately contacts a part of the air motor, such as the air motor housing or the exit side of a poppet valve. The icing can clog the exhaust of the air motor, causing the air motor to seize. 
     Further, the poppet valves in an air motor are embedded in the body of the housing of the air motor. The poppet valves are not exposed to the ambient environmental temperature and have substantial cooling due to conduction between the poppet valves and the adjacent air motor housing. The substantial cooling causes icing on the poppet valve and immediately downstream of the poppet valve. This icing can cause the air motor to seize as the poppet valves are no longer able to actuate the air motor control valve due to ice accumulation. Because the poppet valve is embedded in the body of the housing of the air motor, the poppet valve may not be removable from the air motor without disassembling at least a portion of the air motor. 
     SUMMARY 
     According to an aspect of the disclosure, an air motor assembly includes an air motor cylinder, an exhaust manifold extending at least partially around the air motor cylinder, and a control valve configured to provide motive fluid to the air motor cylinder and to receive exhaust fluid from the air motor cylinder. The exhaust manifold has an exhaust inlet, an exhaust outlet, and an exhaust passage extending between the exhaust inlet and the exhaust outlet. The control valve includes an exhaust port in fluid communication with the exhaust passage. The exhaust port is disposed on a port axis and includes an expansion chamber extending into the exhaust inlet of the exhaust manifold. 
     According to another aspect of the disclosure, a sprayer includes a pump, and an air motor assembly operatively connected to the pump. The air motor assembly includes an air motor cylinder, a reciprocating piston disposed within the air motor cylinder, a connecting rod extending between and connected to the reciprocating piston and the pump, an exhaust manifold extending at least partially around the air motor cylinder, and a control valve configured to provide motive fluid to the air motor cylinder and to receive exhaust fluid from the air motor cylinder. The exhaust manifold has an exhaust inlet, an exhaust outlet, and an exhaust passage extending between the exhaust inlet and the exhaust outlet. The control valve includes an exhaust port in fluid communication with the exhaust passage. The exhaust port is disposed on a port axis and includes an expansion chamber extending into the exhaust inlet of the exhaust manifold. 
     According to a further aspect of the disclosure, a method includes directing driving air (e.g., motive fluid) from an air inlet to a first port, with a shuttle, the first port fluidly connected to an air motor cylinder; directing exhaust air (e.g., exhaust fluid) from a second port to an exhaust port, with the shuttle, the second port fluidly connected to the air motor cylinder; flowing the exhaust air through the exhaust port prior to the exhaust air entering an exhaust manifold, wherein the exhaust port receives the exhaust air from the shuttle through a port inlet and ejects the exhaust air to the exhaust manifold through an expansion chamber. The exhaust port includes a first wall extending from the port inlet, which has a first width, to an outlet having a second width greater than the first width, wherein the first wall is disposed substantially parallel to a port axis of the exhaust port; a second wall opposing the first wall, the second wall extending from the inlet to an upstream end of the expansion chamber, the second wall disposed substantially parallel to the port axis; and a third wall extending from the second wall to the outlet, the third wall disposed transverse to the port axis. The expansion chamber is defined between the first wall and the third wall. 
     According to a further aspect of the disclosure, an air motor assembly includes an air motor cylinder, a control valve, a first poppet valve, a first poppet line, a second poppet valve, and a second poppet line. The air motor cylinder includes an upper cylinder housing having an upper port, a lower cylinder housing having a lower port, a motor cylinder disposed between the upper cylinder housing and the lower cylinder housing, and a piston disposed within the motor cylinder and configured to reciprocate within the motor cylinder between the upper cylinder housing and the lower cylinder housing. The control valve is configured to direct air to the upper port and the lower port in an alternating manner to drive reciprocation of the piston. The first poppet valve is disposed on an exterior of the upper cylinder housing. The first poppet line extends from the first poppet valve to the control valve. The second poppet valve is disposed on an exterior of the lower cylinder housing. The second poppet line extends from the second poppet valve to the control valve. The first poppet valve and the second poppet valve are configured to control actuation of a shuttle of the control valve. The first poppet line and the second poppet line are disposed external to the air motor cylinder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a sprayer system. 
         FIG. 2A  is an isometric view of an air motor assembly with a valve cover removed. 
         FIG. 2B  is another isometric view of an air motor assembly. 
         FIG. 2C  is a side elevation view of an air motor assembly. 
         FIG. 2D  is an exploded view of an air motor. 
         FIG. 3A  is a partially exploded view of an air motor assembly. 
         FIG. 3B  is an isometric cross-sectional view of the air motor assembly of  FIG. 3A  taken along line B-B in  FIG. 2C . 
         FIG. 3C  is an elevation cross-sectional view of the air motor assembly of  FIG. 3A  taken along line B-B in  FIG. 2C . 
         FIG. 3D  is a cross-sectional view of an air motor assembly taken along line D-D in  FIG. 2C . 
         FIG. 4A  is a partially exploded view of an air motor assembly. 
         FIG. 4B  is a cross-sectional view of the air motor assembly shown in  FIG. 4A . 
         FIG. 5A  is a side elevation view of an exhaust chute. 
         FIG. 5B  is a cross-sectional view of the exhaust chute of  FIG. 5A  taken along line B-B in  FIG. 5A . 
         FIG. 5C  is a cross-sectional view of the exhaust chute of  FIG. 5A  taken along line C-C in  FIG. 5A . 
         FIG. 6A  is a partially exploded view of an air motor assembly. 
         FIG. 6B  is a partially exploded view of an air motor assembly. 
         FIG. 6C  is a detail elevation view of a poppet valve of an air motor assembly. 
         FIG. 7A  is an exploded view of a poppet valve. 
         FIG. 7B  is a top elevation view of a poppet valve. 
         FIG. 7C  is a cross-sectional view of a poppet valve taken along line C-C in  FIG. 7B . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an isometric view of sprayer system  10 . Sprayer system  10  includes sprayer  12 , fluid supply  14 , air supply  16 , applicator  18 , and hoses  20   a - 20   c . Sprayer  12  includes frame  22 , wheels  24 , air motor assembly  26 , and pump  28 . Air motor  30  of air motor assembly  26  includes motor cylinder  32 , exhaust manifold  34 , and connecting rod  36 . 
     Air motor assembly  26  is disposed on and supported by frame  22 . Pump  28  is also connected to and supported by frame  22 . Wheels  24  are mounted to frame  22 . Motor cylinder  32  encloses reciprocating components of air motor  30 . Connecting rod  36  is attached to and driven by the reciprocating components. Connecting rod  36  extends from motor cylinder  32  and is attached to pump  28 . Connecting rod  36  is configured to drive reciprocation of a pumping component of pump  28 , such as a piston or diaphragm. 
     Exhaust manifold  34  extends around motor cylinder  32 . A control valve, such as control valve  38  (best seen in  FIG. 3A ), is mounted to motor cylinder  32  and configured to direct compressed air from air supply  16  to motor cylinder  32 , and to direct exhaust gas from motor cylinder  32  to exhaust manifold  34 . Valve cover  46  encloses the control valve. Exhaust gas is compressed air that has already driven the reciprocating components through an upstroke or a downstroke. As such, the compressed air provided by air supply  16  becomes exhaust gas when the reciprocating components reverse stroke direction. 
     Air supply  16  is connected to the control valve by hose  20   a . Air supply  16  is configured to compress air and provide the compressed air to air motor assembly  26  to power air motor  30 . Fluid supply  14  stores a supply of fluid for spraying. Fluid supply  14  is connected to pump  28  by hose  20   b . Hose  20   c  extends from pump  28  to applicator  18 . Pump  28  is configured to draw fluid from fluid supply through hose  20   b  and pump the fluid to applicator  18  through hose  20   c . Applicator  18  applies the pumped fluid to a desired surface. 
     During operation, the control valve directs the compressed air from air supply  16  to opposing sides of the reciprocating components in motor cylinder  32  to drive reciprocation of those components. The compressed air directed to air supply  16  is motive fluid that drives reciprocation of the components in motor cylinder  32 . The control valve also receives exhaust gas (e.g., exhaust fluid) from motor cylinder  32  and directs the exhaust gas to exhaust manifold  34 . Exhaust manifold  34  ejects the exhaust gas to the atmosphere. 
       FIG. 2A  is an isometric view of air motor assembly  26  with valve cover  46  removed so that control valve  38  can be seen.  FIG. 2B  is another isometric view of air motor assembly  26 .  FIG. 2C  is a side elevation view of air motor assembly  26 .  FIG. 2D  is an exploded view of air motor  30 .  FIGS. 2A-2D  will be discussed together. Air motor assembly  26  includes air motor  30 , control valve  38  (best seen in  FIG. 2A ), poppet valves  40   a - 40   b , and poppet lines  42   a - 42   b . Air motor  30  includes motor cylinder  32 , exhaust manifold  34 , connecting rod  36 , piston  44  ( FIG. 2D ), valve cover  46  ( FIGS. 2B-2C ), and loop  48 . Motor cylinder  32  includes upper cylinder housing  50  ( FIGS. 2A, 2C, and 2D ), lower cylinder housing  52  ( FIGS. 2B, 2C , and  2 D), and cylinder sleeve  54  ( FIG. 2D ). Upper cylinder housing  50  includes upper port  56  ( FIG. 2D ), and lower cylinder housing  52  includes lower port  58  ( FIG. 2D ). Control valve  38  includes air inlet  60  and poppet ports  62   a - 62   b . Exhaust manifold  34  includes exhaust inlet  64  ( FIG. 2D ). Piston  44  includes piston plate  66  and seal  68 . 
     As best seen in  FIG. 2D , fasteners  69  extend through upper cylinder housing  50  into lower cylinder housing  52 . Cylinder sleeve  54  is clamped between upper cylinder housing  50  and lower cylinder housing  52 . Seal  70   a  is disposed between cylinder sleeve  54  and upper cylinder housing  50  to prevent air from leaking between cylinder sleeve  54  and upper cylinder housing  50 . Seal  70   b  is disposed between cylinder sleeve  54  and lower cylinder housing  52  to prevent air from leaking between cylinder sleeve  54  and lower cylinder housing  52 . Loop  48  is attached to upper cylinder housing  50  to facilitate lifting of air motor  30 . 
     Piston  44  is disposed within cylinder sleeve  54  and is configured to reciprocate through an upstroke and a downstroke, as indicated in  FIG. 2C , to drive reciprocation of connecting rod  36 . Seal  68  extends around piston plate  66  and prevents the compressed air from flowing past piston plate  66 . Connecting rod  36  extends from piston plate  66  through lower cylinder housing  52 . Seals  72  extend around connecting rod  36  to prevent air from leaking between connecting rod  36  and lower cylinder housing  52 . Connecting rod  36  is connected to pump  28  ( FIG. 1 ) and configured to drive pump  28 . While air motor  30  is shown as including piston  44 , it is understood that air motor  30  can include any suitable actuator for driving reciprocation of connecting rod  36 , such as a flexible diaphragm disposed in cylinder sleeve  54  with connecting rod  36  extending from the flexible diaphragm. 
     Upper port  56  extends into upper cylinder housing  50  and is fluidly connected to an interior area of cylinder sleeve  54  disposed between piston  44  and upper cylinder housing  50 . Lower port  58  extends into lower cylinder housing  52  and is fluidly connected to an interior area of cylinder sleeve  54  disposed between piston plate  66  and lower cylinder housing  52 . Control valve  38  is mounted to exhaust manifold  34  and is configured to direct air to and receive exhaust gas from upper port  56  and lower port  58 . Valve cover  46  is mounted on exhaust manifold  34  and encloses control valve  38  during operation. 
     Control valve  38  receives compressed air from air supply  16  ( FIG. 1 ) through air inlet  60 . Exhaust manifold  34  extends around cylinder sleeve  54  and provides a pathway for exhaust gases to exit air motor  30 . Control valve  38  ejects exhaust gas into exhaust manifold  34  through exhaust inlet  64 . Exhaust inlet  64  is oriented vertically, such that height H of exhaust inlet  64  is larger than width W of exhaust inlet  64 . Orienting exhaust inlet  64  vertically spaces exhaust inlet  64  from cylinder sleeve  54  and discourages the exhaust gas from expanding towards cylinder sleeve  54  when the exhaust gas enters exhaust inlet  64 . 
     Poppet valve  40   a  is disposed on upper cylinder housing  50 . Poppet line  42   a  extends from poppet valve  40   a  to poppet port  62   a  on control valve  38 . Poppet valve  40   b  is disposed on lower cylinder housing  52 . Poppet line  42   b  extends from poppet valve  40   b  to poppet port  62   b  on control valve  38 . 
     Control valve  38  directs compressed air from air source to upper port  56  and lower port  58  in an alternating manner to cause piston  44  to proceed through the upstroke and the downstroke. The compressed air that causes reciprocation of piston  44  can be referred to as motive fluid, driving fluid, driving air, and/or motive air. The shuttle within control valve  38  directs the compressed air from air supply  16  to either upper port  56 , to drive connecting rod  36  through a downstroke, or to lower port  58 , to drive connecting rod  36  through an upstroke. The shuttle directs exhaust gas from the other of upper port  56  and lower port  58  to exhaust manifold  34 . 
     Poppet lines  42   a ,  42   b  are pressurized by the compressed air flowing through control valve  38 . Poppet valves  40   a ,  40   b  control pressurization of poppet lines  42   a ,  42   b  to control movement of a shuttle disposed within control valve  38 . The pressure within poppet lines  42   a ,  42   b  is balanced with both poppet valves  40   a ,  40   b  closed, such that the shuttle is stationary. Piston  44  is configured to contact and open one of poppet valve  40   a ,  40   b  when piston  44  reaches the end of a stroke. Opening one of poppet valve  40   a ,  40   b  allows the air in poppet line  42   a ,  42   b  to vent through poppet valve  40   a ,  40   b , reducing the pressure on one side of the shuttle. The pressure in the other poppet line  42   a ,  42   b  actuates the shuttle, and the shuttle redirects the air flowing to control valve  38  and causes piston  44  to reverse stroke direction. 
     During a downstroke, control valve  38  directs the compressed air to upper port  56 . Upper port  56  provides the compressed air to cylinder sleeve  54 , and the compressed air drives piston  44  downward, causing connecting rod  36  to proceed through the downstroke. The downward movement of piston  44  drives the air disposed in cylinder sleeve  54  between piston  44  and lower cylinder housing  52  out of cylinder sleeve  54  through lower port  58 . This air is exhaust gas. The exhaust gas flows from lower port  58  to control valve  38 , and the shuttle of control valve  38  directs the exhaust air to exhaust manifold  34 . When piston  44  reaches the end of the downstroke, piston plate  66  impacts a rod of poppet valve  40   b , causing poppet valve  40   b  to open and vent the pressurized air in poppet line  42   b  to the atmosphere. The pressure in poppet line  42   b  becomes lower than the pressure in poppet line  42   a , such that the pressurized air in poppet line  42   a  causes the shuttle of control valve  38  to shift positions. In the new position, the shuttle directs the compressed air from air supply  16  to lower port  58  and receives exhaust gas from upper port  56 . 
     During an upstroke, control valve  38  directs the compressed air to lower port  58 . Lower port  58  provides the compressed air to cylinder sleeve  54 , and the compressed air drives piston  44  into the upstroke. As piston  44  begins the upstroke, poppet valve  40   b  closes, and the compressed air flowing through control valve  38  repressurizes poppet line  42   b . The upward movement of piston  44  drives the air previously provided to cylinder sleeve  54  through upper port  56  out of upper port  56  as exhaust gas. The exhaust gas flows from upper port  56  to control valve  38 , and control valve  38  directs the exhaust air to exhaust manifold  34  through exhaust inlet  64 . When piston  44  reaches the end of the upstroke, piston plate  66  impacts a rod of poppet valve  40   a , causing poppet valve  40   a  to open and vent the pressurized air in poppet line  42   a . The pressure in poppet line  42   a  is thus lower than the pressure in poppet line  42   b , such that the pressurized air in poppet line  42   b  causes the shuttle of control valve  38  to shift positions. The shuttle directs the compressed air from air supply  16  to upper port  56  and receives exhaust gas from lower port  58 . The compressed air drives piston  44  through another downstroke. 
       FIG. 3A  is a partially exploded view of air motor assembly  26 .  FIG. 3B  is an isometric cross-sectional view of air motor assembly  26  taken along line B-B in  FIG. 2C .  FIG. 3C  is a cross-sectional view of air motor assembly  26  taken along line B-B in  FIG. 2C .  FIG. 3D  is a cross-sectional view of air motor assembly  26  taken along line C-C in  FIG. 2C .  FIGS. 3A-3D  will be discussed together. Air motor  30 , control valve  38  ( FIGS. 3A-3C ), poppet valve  40   a  ( FIG. 3A ), poppet line  42   a  ( FIG. 3A ), and poppet line  42   b  ( FIG. 3A ) of air motor assembly  26  are shown. Air motor  30  includes motor cylinder  32 , exhaust manifold  34 , connecting rod  36  ( FIG. 3A ), piston  44  ( FIGS. 3B and 3C ), valve cover  46  ( FIGS. 3A-3C ), and loop  48  ( FIG. 3A ). Motor cylinder  32  includes upper cylinder housing  50  ( FIGS. 3A and 3D ), lower cylinder housing  52  ( FIGS. 3A and 3D ), and cylinder sleeve  54  ( FIGS. 3B-3D ). Upper cylinder housing  50  includes upper port  56  ( FIG. 3A ). Lower cylinder housing  52  includes lower port  58  ( FIG. 3A ). Control valve  38  includes valve housing  74 , valve gasket  76 , exhaust block  78 , and shuttle  80  ( FIGS. 3B and 3C ). Valve housing  74  includes air inlet  60  ( FIG. 3A ) and poppet ports  62   a - 62   b  ( FIG. 3A ). Exhaust block  78  includes first port  82  ( FIGS. 3B and 3C ), second port  84  ( FIGS. 3B and 3C ), exhaust port  86  ( FIGS. 3B-3D ), first arm  88  ( FIG. 3A ), and second arm  90  ( FIG. 3A ). Exhaust port  86  includes port inlet  92 , port outlet  94 , first sidewall  96 , second sidewall  98 , and expansion chamber  100 . Second sidewall  98  includes upstream portion  102  and downstream portion  104 . Exhaust manifold  34  includes exhaust inlet  64 , exhaust outlet  106  ( FIGS. 3B and 3C ), inner wall  108 , outer wall  110 , and exhaust passage  112 . 
     Exhaust manifold  34  is mounted on motor cylinder  32 . Exhaust inlet  64  extends into exhaust manifold  34  and is configured to receive exhaust gas from control valve  38 . Exhaust passage  112  extends through exhaust manifold  34  between inner wall  108  and outer wall  110  and provide a flowpath for exhaust to flow from exhaust inlet  64  to exhaust outlet  106 . Exhaust outlet  106  extends into exhaust manifold  34  at an opposite end of exhaust passage  112  from exhaust inlet  64 , and exhaust outlet  106  is configured to expel the exhaust gas to the atmosphere. 
     Upper cylinder housing  50  is disposed on top of cylinder sleeve  54  and lower cylinder housing  52  is disposed below cylinder sleeve  54 . Cylinder sleeve  54  is clamped between upper cylinder housing  50  and lower cylinder housing  52  by fasteners  69  extending through upper cylinder housing  50  into lower cylinder housing  52 . Upper port  56  extends into upper cylinder housing  50 , and lower port  58  extends into lower cylinder housing  52 . Poppet valve  40   a  is disposed on upper cylinder housing  50 . Poppet line  42   a  extends from poppet valve  40   a  to poppet port  62   a  of valve housing  74 . Poppet valve  40   b  is disposed on lower cylinder housing  52 . Poppet line  42   b  extends from poppet valve  40   b  to poppet port  62   b  of valve housing  74 . 
     Fasteners  114   a  extend through valve housing  74  and valve gasket  76  into exhaust block  78 . Fasteners  114   b  extend through exhaust block  78  into exhaust manifold  34  to secure control valve  38  to exhaust manifold  34 . Exhaust gasket  116  is disposed between exhaust block  78  and exhaust manifold  34  and extends around exhaust inlet  64 . First arm  88  projects from exhaust block  78  and is attached to upper cylinder housing  50  by fasteners  114   c . First arm  88  provides a flowpath for air to flow between exhaust block  78  and upper cylinder housing  50 . Second arm  90  projects from exhaust block  78  and is attached to lower cylinder housing  52  by fasteners  114   c . Second arm  90  provides a flowpath for air to flow between exhaust block  78  and upper cylinder housing  50 . Valve cover  46  is disposed over control valve  38  and is attached to exhaust manifold  34  by fasteners  114   d.    
     Shuttle  80  is disposed within valve housing  74 . Shuttle  80  directs air from air inlet  60  to first port  82  and second port  84  in an alternating manner to drive piston  44  through the upstroke and downstroke. Shuttle  80  directs exhaust gas from the other one of first port  82  and second port  84  to exhaust port  86 . Valve gasket  76  is disposed between exhaust block  78  and valve housing  74  and provides a surface for shuttle  80  to seal against when directing the air. 
     Exhaust port  86  extends through exhaust block  78  along port axis P-P. Exhaust port  86  provides a flow path for exhaust gas to flow from valve housing  74  to exhaust manifold  34 . Exhaust port  86  is defined between first sidewall  96  and second sidewall  98 . Upstream portion  102  of second sidewall  98  extends from port inlet  92  towards exhaust manifold  34 . Downstream portion  104  of second sidewall  98  extends from upstream portion  102  to port outlet  94  of exhaust block  78 . 
     First sidewall  96  extends axially along port axis P-P between port inlet  92  and port outlet  94 . Upstream portion  102  also extends axially along port axis P-P between port inlet  92  and port outlet  94 . As such, the portion of exhaust port  86  between upstream portion  102  and first sidewall  96  has a substantially constant width PW 1  ( FIG. 3C ). Downstream portion  104  of second sidewall  98  extends transverse to port axis P-P. Port outlet  94  has a width PW 2  ( FIG. 3D ) greater than width PW 1 . As shown in  FIG. 3D , port outlet  94  has height PH, which is larger than width PW 2  of port outlet  94 . Moreover, port outlet  94  is spaced from inner wall  108  of exhaust manifold  34  by length L 1 , spaced from outer wall  110  of exhaust manifold  34  by length L 2 , spaced from the top of exhaust manifold  34  by length L 3 , and spaced from the bottom of exhaust manifold  34  by length L 4 . Spacing port outlet  94  from each wall of exhaust manifold  34  allows for further expansion and cooling of the exhaust gas prior to impinging on any surface of exhaust manifold  34 . 
     Downstream portion  104  and first sidewall  96  define expansion chamber  100  through exhaust port  86 . Expansion chamber  100  expands away from inner wall  108  of exhaust manifold  34  such that the exhaust gasses flow tangential to or away from inner wall  108 . Having expansion chamber  100  expand away from inner wall  108  prevents the exhaust gasses from impinging on inner wall  108 . Expansion chamber  100  extends towards outer wall  110 , which is exposed to the atmosphere and thus less susceptible to icing than inner wall  108 . 
     First sidewall  96  is disposed tangential to inner wall  108  of exhaust manifold  34 . As shown, first sidewall  96  is spaced from inner wall  108  by offset length L 1 . It is understood that length L 1  can be any desired length greater than or equal to zero. Having offset length L 1  greater than or equal to zero ensures that the exhaust gas exiting exhaust port  86  does not impinge on inner wall  108 . 
     During operation, air supply  16  ( FIG. 1 ) provides compressed air to valve housing  74 . Motor cylinder  32  cools substantially during operation due to the Venturi effect and the Ideal Gas Law. Inner wall  108  of exhaust manifold  34  also cools significantly due to conduction from cylinder sleeve  54 . With shuttle  80  in the position shown in  FIG. 3B , shuttle  80  directs the air received from air supply  16  to first port  82 . The compressed air enters first port  82  and flows through first arm  88  to upper port  56 . The compressed air enters cylinder sleeve  54  through upper port  56  and drives piston  44  through a downstroke. 
     As piston  44  is driven through the downstroke, piston  44  drives exhaust gas out of cylinder sleeve  54  through lower port  58 . The exhaust gas flows through second arm  90  and enters exhaust block  78  through second port  84 . Shuttle  80  directs the exhaust gas from second port  84  to exhaust port  86 . 
     The exhaust air enters exhaust port  86  through port inlet  92  and flows between first sidewall  96  and second sidewall  98 . Expansion chamber  100  between downstream portion  104  of second sidewall  98  and first sidewall  96  causes a pressure drop in the exhaust gas. The pressure drop causes a temperature drop in the exhaust gas. The temperature drop causes the water vapor within the exhaust gas to freeze into ice particles before the exhaust gas impinges on exhaust manifold  34 , preventing ice from accumulating within exhaust manifold  34 . The ice particles are carried through exhaust passage  112  by the exhaust gas and are ejected from exhaust manifold  34  through exhaust outlet  106 . 
     When piston  44  reaches the end of the downstroke, piston  44  impacts rod  164   b  ( FIG. 6B ) of poppet valve  40   b , thereby opening poppet valve  40   b  and allowing air within poppet line  42   b  to vent through poppet valve  40   b.    
     The air pressure within poppet line  42   a  causes shuttle  80  to shift positions within valve housing  74 , such that shuttle  80  directs the air from air supply  16  to second port  84  and fluidly connects first port  82  and exhaust port  86 . The compressed air enters second port  84  and flows through second arm  90  to lower port  58 . The compressed air enters cylinder sleeve  54  through lower port  58  and drives piston  44  through an upstroke. 
     As piston  44  is driven through the upstroke, piston  44  drives exhaust gas out of cylinder sleeve  54  through upper port  56 . The exhaust gas flows through first arm  88  and enters exhaust block  78  through first port  82 . Shuttle  80  directs the exhaust air from first port  82  to exhaust port  86 . Expansion chamber  100  causes a pressure drop in the exhaust gas, which causes a temperature drop in the exhaust gas. The temperature drop causes the water vapor within the exhaust gas to freeze into ice particles before the exhaust gas impinges on exhaust manifold  34 . The ice particles are carried through exhaust passage  112  by the exhaust gas and are ejected from exhaust manifold  34  through exhaust outlet  106 . By causing the water vapor to freeze prior to impinging on exhaust manifold  34 , expansion chamber  100  prevents ice accumulation within exhaust manifold  34 . 
     Exhaust port  86  provides significant advantages. Orienting exhaust port  86  on axis P-P tangential to inner wall  108  of exhaust manifold  34  prevents the exhaust gas from impinging on exhaust manifold  34 . Preventing impingement allows the water vapor to freeze in the air instead of on any surface of exhaust manifold  34 , which prevents ice buildup. In addition, expansion chamber  100  between downstream portion  104  of second sidewall  98  and first sidewall  96  causes the pressure drop, which causes the temperature drop that allows the water vapor to freeze prior to impinging on exhaust manifold  34 . Moreover, orienting first sidewall  96  substantially axial with port axis P-P and downstream portion  104  transverse to port axis P-P causes the exhaust gas to expand away from inner wall  108 , further discouraging icing on inner wall  108 . Spacing first sidewall  96  from inner wall  108  by offset length L 1  further prevents the exhaust gas from impinging on inner wall  108  as the exhaust gas exits expansion chamber  100 . 
       FIG. 4A  is a partially exploded view of air motor assembly  26 ′.  FIG. 4B  is a cross-sectional view of air motor assembly  26 ′.  FIGS. 4A and 4B  will be discussed together. Air motor assembly  26 ′ includes air motor  30 , control valve  38 , poppet valve  40   a  ( FIG. 4A ), poppet valve  40   b  (not shown), poppet lines  42   a - 42   b  ( FIG. 4A ), and exhaust chute  118 . Air motor  30  includes motor cylinder  32 , exhaust manifold  34 , connecting rod  36  ( FIG. 4A ), piston  44  ( FIG. 4B ), valve cover  46 , and loop  48  ( FIG. 4A ). Motor cylinder  32  includes upper cylinder housing  50  ( FIG. 4A ), lower cylinder housing  52  ( FIG. 4A ), and cylinder sleeve  54  ( FIG. 4B ). Upper cylinder housing  50  includes upper port  56  ( FIG. 4A ). Lower cylinder housing  52  includes lower port  58  ( FIG. 4A ). Control valve  38  includes valve housing  74 , valve gasket  76 , exhaust block  78 , and shuttle  80  ( FIG. 4B ). Air inlet  60  ( FIG. 4A ) and poppet port  62   a  ( FIG. 4A ) of valve housing  74  are shown. Exhaust block  78  includes first port  82  ( FIG. 4B ), second port  84  ( FIG. 4B ), exhaust port  86  ( FIG. 4B ), first arm  88  ( FIG. 4A ), and second arm  90  ( FIG. 4A ). Exhaust port  86  includes port inlet  92  ( FIG. 4B ), port outlet  94  ( FIG. 4B ), first sidewall  96  ( FIG. 4B ), second sidewall  98  ( FIG. 4B ), and expansion chamber  100  ( FIG. 4B ). Second sidewall  98  includes upstream portion  102  ( FIG. 4B ) and downstream portion  104  ( FIG. 4B ). Exhaust manifold  34  includes exhaust inlet  64 , exhaust outlet  106  ( FIG. 4B ), inner wall  108 , outer wall  110 , and exhaust passage  112  ( FIG. 4B ). Exhaust chute  118  includes chute body  120 , chute flange  122 , chute inlet  124 , and chute outlet  126  ( FIG. 4B ). Chute body  120  includes first chute wall  128  ( FIG. 4B ) and second chute wall  130  ( FIG. 4B ). Second chute wall  130  includes curved portion  132  ( FIG. 4B ). 
     Air motor assembly  26 ′ is substantially similar to air motor assembly  26  (best seen in  FIGS. 3A-3D ), except air motor assembly  26 ′ further includes exhaust chute  118 . Exhaust chute  118  extends into exhaust passage  112  of exhaust manifold  34  through exhaust inlet  64 . Chute flange  122  is disposed between exhaust block  78  and exhaust manifold  34 . Exhaust chute  118  is connected to exhaust block  78  by fasteners  114 e extending through chute flange  122  into exhaust block  78 . Chute seal  133  is disposed between chute flange  122  and exhaust block  78 . Chute body  120  extends through exhaust inlet  64  into exhaust passage  112 . Chute inlet  124  is disposed adjacent port outlet  94  to receive exhaust gas from port outlet  94 . Chute outlet  126  is disposed at an opposite end of chute body  120  from chute inlet  124 . First chute wall  128  extends substantially axially along port axis P-P. Second chute wall  130  also extends substantially axially along port axis P-P from chute inlet  124  to curved portion  132 . Curved portion  132  is disposed at a distal end of second chute wall  130  proximate chute outlet  126 . Curved portion  132  is transverse to port axis P-P and is configured to guide the exhaust gas into exhaust passage  112 . 
     During operation, the exhaust gas from exhaust port  86  enters exhaust chute  118  through chute inlet  124 . Exhaust chute  118  guides the exhaust gas past the portion of inner wall  108  nearest exhaust port  86 . Curved portion  132  turns the exhaust gas such that the exhaust gas flows tangential to inner wall  108  when the exhaust gas is expelled through chute outlet  126 . Exhaust chute  118  reduces noise caused by the expanding exhaust gas flowing through exhaust port  86  and further prevents icing on surfaces of exhaust manifold  34 . 
       FIG. 5A  is a side elevation view of exhaust chute  118 .  FIG. 5B  is a cross-sectional view of exhaust chute  118  taken along line B-B in  FIG. 5A .  FIG. 5C  is a cross-sectional view of exhaust chute  118  taken along line C-C in  FIG. 5A .  FIGS. 5A-5C  will be discussed together. Exhaust chute  118  includes chute body  120 , chute flange  122 , chute inlet  124 , chute outlet  126 , and liner  134 . Chute body  120  includes first chute wall  128  ( FIG. 5B ) and second chute wall  130  ( FIG. 5B ). Second chute wall  130  includes curved portion  132  ( FIG. 5B ). Chute outlet  126  includes crenulations  136 . 
     Exhaust chute  118  is typically made of a plastic or other non-metallic substance to lower the thermal conductivity of exhaust chute  118 . Chute flange  122  extends around chute inlet  124 . First chute wall  128  extends from chute inlet  124  to chute outlet  126 . Second chute wall  130  extends from chute inlet  124 , and curved portion  132  is disposed at chute outlet  126 . Liner  134  is disposed in chute body  120 . In some examples, liner  134  is a felt liner configured to reduce noise generated by the exhaust. Curved portion  132  is configured to turn air passing through exhaust chute  118 . Crenulations  136  are disposed around chute outlet  126 . Crenulations  136  are configured to generate turbulence in the exhaust passing through chute outlet  126  to thereby break the soundwave and decrease the noise generated by air motor assembly  26 ′ ( FIGS. 4A-4B ). 
       FIG. 6A  is a partially exploded view of air motor assembly  26 .  FIG. 6B  is another partially exploded view of air motor assembly  26 .  FIG. 6C  is a detail bottom elevation view of a portion of air motor assembly  26 . Air motor assembly  26  includes air motor  30 , control valve  38 , poppet valve  40   a  ( FIG. 6A ), poppet valve  40   b  ( FIGS. 6B and 6C ), poppet line  42   a  ( FIG. 6A ), and poppet line  42   b . Motor cylinder  32 , exhaust manifold  34 , connecting rod  36 , and loop  48  of air motor  30  are shown. Upper cylinder housing  50  ( FIG. 6A ) and lower cylinder housing  52  ( FIGS. 6B and 6C ) of motor cylinder  32  are shown. Valve housing  74 , valve gasket  76 , and exhaust block  78  of control valve  38  are shown. 
     Top surface  138 , upper walls  140 , and poppet receiving area  142   a  of upper cylinder housing  50  are shown in  FIG. 6A . Top surface  138  includes fastener openings  144   a  ( FIG. 6A ) and rod opening  146   a  ( FIG. 6A ). Poppet valve  40   a  includes poppet housing  152   a  ( FIG. 6A ), valve assembly  154   a  ( FIG. 6A ), first gasket  156   a  ( FIG. 6A ), second gasket  158   a  ( FIG. 6A ), and insulating sheets  160   a  ( FIG. 6A ). Poppet housing  152   a  includes mounting flange  162   a  ( FIG. 6A ). Valve assembly  154   a  includes rod  164   a  ( FIG. 6A ). 
     Bottom surface  148 , lower walls  150 , and poppet receiving area  142   b  of lower cylinder housing  52  are shown in  FIG. 6B . Bottom surface  148  includes fastener openings  144   b  ( FIG. 6B ) (only one of which is shown) and rod opening  146   b  ( FIG. 6B ). Poppet valve  40   b  includes poppet housing  152   b  ( FIGS. 6B and 6C ), valve assembly  154   b  ( FIGS. 6B and 6C ), first gasket  156   b  ( FIG. 6B ), second gasket  158   b  ( FIG. 6B ), and insulating sheets  160   b  ( FIGS. 6B and 6C ). Poppet housing  152   b  includes mounting flange  162   b  ( FIGS. 6B and 6C ). Valve assembly  154   b  includes rod  164   b  ( FIG. 6B ). 
     Exhaust manifold  34  is disposed around motor cylinder  32 . Upper cylinder housing  50  is disposed on a top side of cylinder sleeve  54  (best seen in  FIG. 2D ). Fastener openings  144   a  extend into top surface  138  and rod opening  146   a  extends through top surface  138 . Upper walls  140  extend from top surface  138  of upper cylinder housing  50  and partially surround poppet valve  40   a . Upper walls  140  define poppet receiving area  142   a . Upper walls  140  protect poppet valve  40   a  from undesired contact during operation. 
     Poppet valve  40   a  is mounted on top surface  138  within poppet receiving area  142   a . Insulating sheets  160   a  are disposed between poppet valve  40   a  and upper walls  140  to thermally isolate poppet valve  40   a  from upper walls  140 . First gasket  156   a  is disposed between top surface  138  and mounting flange  162  of poppet housing  152   a  to thermally insulate poppet housing  152   a  from upper cylinder housing  50 . Second gasket  158   a  is disposed on an opposite side of mounting flange  162   a  from first gasket  156   a . Fasteners  166   a  extend through second gasket  158   a , mounting flange  162   a , and first gasket  156   a  and into fastener openings  144   a  in top surface  138  to connect poppet valve  40   a  to upper cylinder housing  50 . Second gasket  158   a  prevents the heads of fasteners  166   a  from contacting mounting flange  162   a . 
     As discussed above, motor cylinder  32  experiences significant cooling during operation. First gasket  156   a , second gasket  158   a , and insulating sheets  160   a  thermally isolate poppet valve  40   a  from upper cylinder housing  50  to prevent icing in poppet valve  40   a . With poppet valve  40   a  secured to top surface  138  by fasteners  166   a , the only conduction path between upper cylinder housing  50  and poppet valve  40   a  is at the interface of fasteners  166   a  and mounting flange  162   a  where fasteners  166   a  extend through mounting flange  162   a . It is understood, however, that a bushing formed from a thermal insulation material can be placed in the fastener openings extending through mounting flange  162   a  to fully thermally isolate poppet valve  40   a  from upper cylinder housing  50 . 
     Poppet line  42   a  extends from poppet housing  152   a  to control valve  38 . Poppet line  42   a  contains pressurized air that controls the actuation of shuttle  80  (best seen in  FIG. 3B ) within valve housing  74 . Poppet line  42   a  is external to motor cylinder  32 , which thermally isolates poppet line  42   a  from motor cylinder  32  and exposes poppet line  42   a  to the atmosphere. Disposing poppet line  42   a  external to motor cylinder  32  prevents icing within poppet line  42   a.    
     Lower cylinder housing  52  is disposed on a bottom side of cylinder sleeve  54  (best seen in  FIG. 2D ). Fastener openings  144   b  extend into bottom surface  148  and rod opening  146   b  extends through bottom surface  148 . Lower walls  150  extend from bottom surface  148  of lower cylinder housing  52  and partially surround poppet valve  40   b . Lower walls  150  define poppet receiving area  142   b . Poppet valve  40   b  is mounted on bottom surface  148  within poppet receiving area  142   b . Lower walls  150  protect poppet valve  40   b  from undesired contact during operation. 
     Insulating sheets  160   b  are disposed between poppet valve  40   b  and lower walls  150  to thermally isolate poppet valve  40   b  from lower walls  150 . First gasket  156   b  is disposed between bottom surface  148  and mounting flange  162   b  of poppet housing  152   b  to thermally insulate poppet housing  152   b  from lower cylinder housing  52 . Second gasket  158   b  is disposed on an opposite side of mounting flange  162   b  from first gasket  156   b . Fasteners  166   b  extend through second gasket  158   b , mounting flange  162   b , and first gasket  156   b  and into bottom surface  148  to secure poppet valve  40   b  to lower cylinder housing  52 . Second gasket  158   b  prevents the heads of fasteners  166   b  from contacting mounting flange  162   b.    
     First gasket  156   b , second gasket  158   b , and insulating sheets  160   b  thermally isolate poppet valve  40   b  from lower cylinder housing  52  during operation. With poppet valve  40   b  secured to bottom surface  148  by fasteners  166   b , the only conduction path between lower cylinder housing  52  and poppet valve  40   b  is at the interface of fasteners  166   b  and mounting flange  162   b  where fasteners  166   b  extend through mounting flange  162   b . It is understood, however, that a bushing formed from a thermal insulation material can be placed in the fastener openings extending through mounting flange  162   b  to fully thermally isolate poppet valve  40   b  from lower cylinder housing  52 . 
     Poppet line  42   b  extends from poppet housing  152   b  to control valve  38 . Poppet line  42   b  contains pressurized air that controls the actuation of shuttle  80  within valve housing  74 . Poppet line  42   b  is disposed external to motor cylinder  32 , which thermally isolates poppet line  42   b  from motor cylinder  32  and exposes poppet line  42   b  to the atmosphere. Disposing poppet line  42   b  external to motor cylinder  32  prevents icing within poppet line  42   b.    
     Thermally isolating poppet valves  40   a ,  40   b  and poppet lines  42   a ,  42   b  from motor cylinder  32  provides significant advantages. First gasket  156  and second gasket  158  lower the thermal conductivity between motor cylinder  32  and poppet valves  40   a ,  40   b  by limiting the surface area of poppet valves  40   a ,  40   b  in contact with motor cylinder  32 . Limiting contact inhibits ice formation in poppet valves  40   a ,  40   b  that can cause air motor  30  to seize. In addition, poppet valves  40   a ,  40   b  being on the exterior of motor cylinder  32  exposes poppet valves  40   a ,  40   b  to the ambient environment, which further inhibits icing in poppet valves  40   a ,  40   b . Poppet lines  42   a ,  42   b  being external to motor cylinder  32  also inhibits icing by thermally isolating poppet lines  42   a ,  42   b  from motor cylinder  32 . While air motor assembly  26  is described as including both insulating sheets  160   a ,  160   b , it is understood that air motor assembly  26  can include only one set of insulating sheets  160   a ,  160   b . In some examples, air motor assembly  26  includes insulating sheets  160   b  on a bottom of air motor assembly  26  but not insulating sheets  160   a.    
       FIG. 7A  is a partially exploded view of poppet valve  40 .  FIG. 7B  is a top elevation view of poppet valve  40 .  FIG. 7C  is a cross-sectional view of poppet valve  40  taken along line C-C in  FIG. 7B .  FIGS. 7A-7C  will be discussed together. Poppet housing  152  and valve assembly  154  of poppet valve  40  are shown. Poppet housing  152  includes mounting flange  162 , receiving cylinder  168 , and line port  170 . Mounting flange  162  includes fastener openings  163 . Receiving cylinder  168  includes vents  172 . Valve assembly  154  includes valve body  174  and valve member  176  ( FIG. 7C ). Valve member  176  includes rod  164 . 
     Valve receiving cylinder  168  extends from mounting flange  162 . Line port  170  extends from valve receiving cylinder  168  and is configured to receive poppet line  42  (best seen in  FIGS. 6A-6B ). Vents  172  extends into valve receiving cylinder  168  and provide a flowpath for air to be vented to the environment from valve receiving cylinder  168 . Fastener openings  163  extend through mounting flange  162  and receive fasteners to secure poppet valve  40  to motor cylinder  32  (best seen in  FIG. 2D ). 
     Valve assembly  154  is removably disposed in valve receiving cylinder  168 . In some examples, valve assembly  154  is secured within valve receiving cylinder  168  by interfacing threads on valve body  174  and valve receiving cylinder  168 . Valve member  176  is disposed within valve body  174 . Rod  164  projects out of poppet housing  152  and is configured to extend into an interior of motor cylinder  32 . 
     Valve member  176  is normally closed, and is movable between a closed position, shown in  FIG. 7C , and an open position. In the closed position, valve member  176  fluidly isolates vents  172  from poppet line  42  to prevent air from exiting valve member  176  through vents  172 . During operation, rod  164  is impacted by piston  44  (best seen in  FIG. 2D ) to drive valve member  176  from the closed position to the open position. In the open position, a flowpath is opened through valve assembly  154  to allow air within poppet line  42  to vent out of vents  172 . Venting the air reduces the pressure within poppet line  42 , thereby reducing the pressure on one side of shuttle  80  (best seen in  FIG. 3B ), allowing shuttle  80  to shift positions. Shifting shuttle  80  causes piston  44  to reverse stroke direction. 
     Valve assembly  154  being removable from valve receiving cylinder  168  provides significant advantages. With valve assembly  154  secured by interfaced threading, valve assembly  154  can be removed by twisting valve assembly  154  relative to valve receiving cylinder  168 . As such, if valve assembly  154  ices during operation, the user can unscrew valve assembly  154  from valve receiving cylinder  168  and heat valve assembly  154  to remove the ice. For example, the user can grasp valve assembly  154  in the user&#39;s hand to heat valve assembly  154  and remove the ice. Furthermore, poppet housing  152  facilitates mounting poppet valve  40  on the exterior of motor cylinder  32 . As such, the user does not need to disassembly air motor  30  to access and deice poppet valve  40 . Less downtime is required to deice poppet valve  40  and the process of deicing poppet valve  40  is thereby simplified. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.