Back pressure regulator

Abstract

A back pressure regulator ("BPR") includes a pressure housing at least partially defining a flow chamber through which a liquid flows, and the BPR has an adjustable restriction that varies with flow to maintain an upstream liquid pressure. The pressure housing is contoured to distribute the liquid flow to provide radial flow into the adjustable restriction from a circumferential perimeter of the adjustable restriction. The pressure housing includes angled and curved side channels that direct the flow, and ridges that separate the flow and prevent internal collisions between the flows. A flow director extends into the chamber outlet to prevent collisions of the radial flows through the annular restriction. The flow director reorients the flows to smoothly recombine in the chamber outlet.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 062,585, filed August 7, 2020, entitled “BACK PRESSURE REGULATOR,” the disclosure of which is hereby incorporated by reference in its entirety. BACKGROUND

[0003] The present disclosure relates to pressure regulation. More particularly, the present disclosure relates to a back pressure regulator in a spray system.

[0004] Spray systems, such as spray systems for applying coatings, paints, finishes, etc., can be configured to spray a variety of fluids having different colors and / or other fluid properties. Each of the variety of fluids circulates within a closed loop when the fluid is not being sprayed. When the fluid is being sprayed, a portion of the fluid continues to circulate. A back pressure regulator is disposed on a return line between an applicator and a storage tank to maintain pressure at the applicator. Pressure causes the spray and affects the quality of the spray and finish. Pressure is controlled at various volumetric flow rates as the fluid circulation volume changes during spraying.

[0005] The back pressure regulator is a restriction in the flow line. The restriction can cause turbulence and collisions within the fluid. For example, the paint can contain metal flakes and can circulate between a paint kitchen and a spray booth. Turbulent areas in the circulation path can cause collisions between the metal flakes, which can damage the metal flakes, adversely affect the color of the paint, and cause undesirable degradation. Prior art back pressure regulators can create significant pressure and flow rate changes that shear the paint, as the fluid enters the orifice from a location closest to the fluid source (e.g., primarily through the front half of the orifice). SUMMARY

[0006] According to one aspect of the present disclosure, a back pressure regulator includes a pressure housing having an outer wall, an inner wall; a flow chamber at least partially defined by the pressure housing, the flow chamber including a chamber inlet through the pressure housing and a chamber outlet through the pressure housing, wherein the flow chamber extends circumferentially around the chamber outlet; and a pressure control member at least partially defining the flow chamber, wherein the pressure control member includes a flow director disposed on a regulator axis and configured to extend at least partially into the chamber outlet. The inner wall is sloped between a lower end and an upper end. The pressure control member is movable between a closed state during which the chamber outlet is closed and an activated state during which an annular restriction between the flow chamber and the chamber outlet is open.

[0007] According to yet alternative aspects of the present disclosure, a method of regulating upstream pressure includes: dividing an inlet flow of a liquid into a first sub-flow and a second sub-flow; flowing the first sub-flow through a first side channel that is angled between an upstream end and a downstream end and curves around a chamber outlet; flowing the second sub-flow through a second side channel that is angled between the upstream end and the downstream end and curves around the chamber outlet; reorienting the first sub-flow and the second sub-flow at the downstream end and toward the chamber outlet; flowing the liquid through an annular restriction to the chamber outlet; and varying a size of the annular restriction based on a volumetric flow rate of the liquid. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 is a schematic block diagram of a spray system.

[0009] FIG. 2A is a side view showing flow through a prior art back pressure regulator.

[0010] FIG. 2B is a top view of the prior art back pressure regulator shown in FIG. 2A showing flow lines through the back pressure regulator.

[0011] Figure 3A is an elevation view of a back pressure regulator.

[0012] Figure 3B is a cross-sectional view taken along line B-B in Figure 3A

[0013] Figure 3C is a cross-sectional view taken along line C-C in Figure 3B

[0014] Figure 3D is a cross-sectional view taken along line D-D in Figure 3B

[0015] Figure 4 is an enlarged view of detail 4 in Figure 3C

[0016] Figure 5A is a cross-sectional view taken along line 5A-5A in Figure 3A

[0017] Figure 5B is a cross-sectional view taken along line 5B-5B in Figure 3B

[0018] Figure 6A is a cross-sectional view showing flow lines through a back pressure regulator.

[0019] Figure 6B is a side view of a back pressure regulator showing flow lines through the back pressure regulator.​​​​​​

[0020] Figure 6C is a top view of a back pressure regulator showing flow lines through the back pressure regulator.

[0021] Figure 7 is a cross-sectional view of a back pressure regulator.

[0022] Figure 8 is a graph showing inlet pressure and flow for a back pressure regulator. DETAILED DESCRIPTION

[0023] The present disclosure relates to back pressure regulators for a spray system. The spray system can be a paint spray system such as for automobiles and the like. The spray system includes one or more spray assemblies, each spray assembly including a back pressure regulator. The spray assemblies can circulate a liquid, such as paint containing metallic flakes, between a reservoir and a sprayer. The liquid is circulated and the back pressure regulator maintains pressure in the line. The back pressure regulator prevents internal impingement within the liquid, thereby preventing undesirable color changes and extending the useful life of the liquid. The back pressure regulator suppresses pressure spikes and maintains a relatively constant upstream pressure at various flow rates, thereby maintaining a constant spray pressure and providing consistent spraying and finishing.

[0024] Figure 1 is a schematic block diagram of a spray system 10. The spray system 10 includes spray assemblies 12, a supply chamber 14, a spray chamber 16, and a sprayer 18. Each spray assembly 12 includes a liquid reservoir 20, a pump 22, a spray valve 24, a back pressure regulator ("BPR") 26, and a pressure circuit 28. Each pressure circuit 28 is formed by a supply line 30 and a return line 32 of the spray assembly 12.

[0025] The spray system 10 is a system configured to generate liquid sprays and apply the liquid sprays to a target substrate. For example, the spray system 10 can be configured to generate and apply sprays of paint, finishes, and other coatings. While a system for applying paint is used as an example herein, such that the spray system 10 can be a paint spray system, it should be understood that the system 10 can be used for various applications. The sprayer 18 receives fluid from multiple spray assemblies 12 and can selectively connect a spray assembly 12 to a nozzle 34 to apply paint from the spray assembly 12. For example, each spray assembly 12 can be configured to provide a different color of paint relative to the other spray assemblies 12. Some spray assemblies 12 can provide solvent or other fluid to flush the sprayer 18 between application of different paints. While the spray system 10 is shown as including three spray assemblies 12, it should be understood that the spray system 10 can include as many or as few spray assemblies 12 as desired.

[0026] Each spray assembly 12 provides liquid from the supply chamber 14 to the spray chamber 16 via a supply line 30 and receives a return flow via a return line 32. A pressure circuit 28 extends from the pump 22 to the BPR 26. A reservoir 20 stores the supplied liquid. The reservoir 20 is disposed in the supply chamber 14, which in some examples can be referred to as a paint kitchen. The supply chamber 14 can be an area of a facility dedicated to storing supplies of paint. The supply chamber 14 can be remote from the spray chamber 16.

[0027] The supply line 30 extends between the reservoir 20 and the sprayer 18. The pump 22 is disposed to pump fluid downstream through the supply line 30. The pump 22 can be disposed downstream of the reservoir 20 on the supply line 30. The pump 22 can have any desired configuration suitable to drive liquid through the supply line 30 and generate a spray pressure in the pressure circuit 28. For example, the pump 22 can be a pneumatic, hydraulic, or electric pump, among others. The pump 22 can be a diaphragm pump, piston pump, plunger pump, or peristaltic pump, among others. Paint is pumped downstream through the supply line 30 to the spray valve 24.

[0028] The spray valve 24 provides a location for fluid to flow out of the pressure circuit formed by the supply line 30 and the return line 32. The spray valve 24 is configured to control flow from the supply assembly 12 to the nozzle 34. With the spray valve 24 in an open state, a bypass portion of the liquid flows downstream from the spray valve 24 through the return line 32, and a spray portion of the liquid flows downstream through the spray valve 24 and to the nozzle 34. With the spray valve 24 in a closed state, the bypass portion is formed of 100% of the liquid pumped downstream by the pump 22. When the spray valve 24 is actuated to an open state, the percentage of the volume flow that forms the bypass portion decreases and can vary depending on how far the spray valve 24 is opened. The volume flow that forms the spray portion rises in relation to the volume flow that forms the bypass portion. The pressure at the spray valve 24 can be the same as the pressure in the bypass portion. The spray portion and the bypass portion can have the same pressure and different flow rates.

[0029] The return line 32 extends from the spray valve 24 to the reservoir 20. The BPR 26 is disposed on the return line 32 between the spray valve 24 and the reservoir 20. The BPR 26 is configured to maintain the actual liquid pressure in the pressure circuit 28 upstream of the BPR 26 at a desired liquid pressure. The pump 22 establishes the pressure in the pressure circuit 28, and the BPR 26 maintains the pressure between the BPR 26 and the pump 22. The BPR 26 is disposed downstream of the pump 22. The BPR 26 is disposed downstream of the spray valve 24.

[0030] The liquid pressure in pressure circuit 28 drives the spray liquid through spray valve 24 and nozzle 34. Thus, when spray valve 24 is in the open state, the pressure causes nozzle 34 to produce a spray of liquid. The pressure in pressure circuit 28 affects the quality and pattern of the spray of liquid emitted by nozzle 34. Maintaining a steady pressure in pressure circuit 28 provides a high quality, uniform, consistent spray. The fluid pressure is set and maintained by BPR 26. BPR 26 includes a variable opening that is adjusted to maintain the actual liquid pressure in pressure circuit 28 upstream of BPR 26. For example, BPR 26 can be supplied with a working fluid, such as compressed air or hydraulic fluid, to control the variable opening and maintain the actual liquid pressure through BPR 26. Thus, BPR 26 can be controlled in a pneumatic or hydraulic manner, among other ways. Liquid flowing downstream from BPR 26 returns to reservoir 20.

[0031] During operation, each spray assembly 12 provides liquid to sprayer 18 under pressure. For each spray assembly 12, pump 22 draws liquid from reservoir 20 and pumps the liquid downstream through supply line 30. A working fluid pressure is set at BPR 26 to maintain the actual liquid pressure within pressure circuit 28 at a desired spray pressure. Spray valve 24 is initially in the closed state, and liquid flows to return line 32. The entire volumetric flow of liquid forms a bypass portion. Liquid flows downstream through return line 32 and to BPR 26. The force exerted by the spray liquid is balanced by the force exerted by the working fluid to control the size of the variable restriction through BPR 26 to maintain the actual liquid pressure at the desired liquid pressure. A portion of the liquid flows downstream from BPR 26 and returns to reservoir 20.

[0032] Spray valve 24 is transitioned to the open state to begin spraying. The spray portion of the liquid flows downstream through spray valve 24 and is emitted as a spray through nozzle 34. The volumetric flow of the bypass portion decreases as spray valve 24 is in the open state. Spray valve 24 is transitioned to the closed state to stop spraying. Transitioning spray valve 24 to the closed state increases the volumetric flow of the bypass portion. The opening to BPR 26 changes as the volumetric flow changes to maintain the actual spray pressure at the desired spray pressure. The size of the opening can increase as the volumetric flow increases and can decrease as the volumetric flow decreases.

[0033] FIG. 2A is a side view showing flow through prior art BPR 1026. FIG. 2B is a top view showing flow chamber 1046 of prior art BPR 1026. BPR 1026 includes flow chamber 1046, regulator inlet 1060, regulator outlet 1062, chamber inlet 1070, and chamber outlet 1072. Flow lines FL show the flow of spray liquid through BPR 1026.

[0034] The spray liquid enters the BPR 1026 at the regulator inlet 1060. The spray liquid flows toward the flow chamber 1046 and is redirected from a substantially horizontal flow to a substantially vertical flow by the vertical wall. The spray liquid enters the flow chamber 1046 through the chamber inlet 1070. As seen most clearly in FIG. 2B, the flow can wrap around the chamber outlet 1072. Multiple portions of the flow collide at the back side of the flow chamber 1046, and this internal collision can cause the spray liquid to deteriorate due to internal collisions (such as between metal flakes in the spray liquid).

[0035] The flow chamber 1046 has a substantially uniform height throughout the flow chamber 1046. The chamber inlet 1070 is disposed at the front end of the flow chamber 1046 and provides the spray liquid to the flow chamber 1046. The spray fluid exits the flow chamber 1046 through the chamber outlet 1072. The flow chamber 1046 is shown divided into an upstream half UH and a downstream half DH. The downstream half DH is divided into a first sector SI, a second sector S2, a third sector S3, and a fourth sector S4. The contouring (contours) of the BPR 1026 is such that 70% or more of the flow exits the flow chamber 1046 from the upstream half UH of the BPR 1026. Less than about 30% of the flow exits the flow chamber 1046 through the downstream half DH. In some examples, only up to about 10% of the flow flows around the chamber outlet 1072 and out through the second sector S2 and the third sector S3, such that about 5% of the flow exits through each of the second sector S2 and the third sector S3. Up to about 15% of the flow exits the flow chamber 1046 through the quadrant formed by the first sector SI and the second sector S2. Up to about 15% of the flow exits the flow chamber 1046 through the quadrant formed by the third sector S3 and the fourth sector S4. The contouring of the BPR 1026 also causes a large acceleration as the spray liquid exits the flow chamber 1046.

[0036] Figure 3A is a side view of the BPR 26. Figure 3B is a cross-sectional view taken along line B-B in Figure 3A . Figure 3C is a cross-sectional view taken along line C-C in Figure 3B . Figure 3D is a cross-sectional view taken along line D-D in Figure 3B . Figures 3A to 3DThey will be discussed together. BPR26 includes a body 36 and a pressure control mechanism 38. The body 36 includes a pressure housing 40 and a control housing 42. BPR 26 also includes a working fluid chamber 44 and a flow chamber 46. The pressure housing 40 includes an inner wall 48, an outer wall 50, base walls 52a and 52b, a regulator shelf 54, an upstream ridge 56, a downstream ridge 58, a regulator inlet 60, a regulator outlet 62, and an inlet hole 64. The flow chamber 46 includes a front end 66, a rear end 68, a chamber inlet 70, a chamber outlet 72, and side channels 74a and 74b. The pressure control mechanism 38 includes a first component 76, a second component 78, a regulator shaft 80, and a seat 82. The first component 76 includes a first plate 84, a first diaphragm 86, and a first fastener 88. The second component 78 includes a guide 90, a lower plate 92, an upper plate 94, a shaft 96, a nut 98, and a second diaphragm 100.

[0037] BPR 26 is configured to regulate and maintain the pressure upstream of BPR 26. Body 36 supports pressure control mechanism 38. Pressure control mechanism 38 is configured to interface with the working fluid and spray liquid to maintain the actual liquid pressure within and upstream of flow chamber 46 at the desired spray pressure. Pressure control mechanism 38 is configured to move along regulator axis AA to change the size of the annular restraint 102 between second member 78 and seat 82. Control housing 42 is connected to pressure housing 40. For example, control housing 42 can be connected to pressure housing 40 via interface threads or fasteners (e.g., bolts).

[0038] A first member 76 is disposed within a control housing 42 and at least partially defines a working fluid chamber 44 within the control housing 42. In the example shown, the first member 76 is a diaphragm comprising a first membrane 86 and a first plate 84. The outer peripheral edge of the first membrane 86 is clamped between an upper and lower portion of the control housing 42. The upper and lower portions can be connected in any desired manner, such as by fasteners (e.g., bolts). Although the first member 76 is shown as a diaphragm, it should be understood that the first member 76 can be any form suitable for sealing the working fluid chamber 44 and interfacing (forming an interfacial connection) with a second member 78 to bias the second member 78 downward into the flow chamber 46. The working fluid chamber 44 is connected to a working fluid source (not shown), such as a hydraulic fluid supply or an air compressor.

[0039] The regulator shaft 80 extends between and transfers force between the first member 76 and the second member 78. In the example shown, the regulator shaft 80 is cylindrical with a closed upper end and an open lower end. The regulator shaft 80 extends between the first member 76 and the second member 78 to transfer force between the first member 76 and the second member 78. The body of the regulator shaft 80 extends through the interface or interface between the control housing 42 and the pressure housing 40. The regulator shaft 80 is configured to move with the first member 76 and the second member 78 relative to the control housing 42 and the pressure housing 40. In the example shown, the first member 76 interfaces with the closed upper end of the regulator shaft 80 and the second member 78 interfaces with the open lower end of the regulator shaft 80. The first member 76 can apply a downward force to the regulator shaft 80 to bias the second member 78 into the flow chamber 46. The second member 78 can apply an upward force to the regulator shaft 80 to bias the first member 76 into the working fluid chamber 44. During operation, the forces are balanced on the regulator shaft 80 to control the size of the annular restriction 102.

[0040] The second member 78 is disposed within the pressure housing 40 and at least partially defines the flow chamber 46. The second member 78 bounds the upper end of the flow chamber 46. In the example shown, the second member 78 is formed as a diaphragm. The second membrane 100 is captured between the upper plate 94 and the lower plate 92. The outer peripheral edge of the second membrane 100 is clamped between the upper portion and the lower portion of the pressure housing 40. The upper portion and the lower portion can be connected in any desired manner, such as by fasteners (e.g., bolts). The upper portion of the pressure housing 40 is connected to the lower portion of the control housing 42. The upper plate 94 interfaces with the regulator shaft 80. The lower plate 92 is exposed to the flow chamber 46 and disposed opposite the seat 82. The shaft 96 extends through each of the lower plate 92, the second membrane 100, and the upper plate 94. The nut 98 is disposed on the shaft 96 and secures the second member 78 together. A seal is disposed at the interface between the upper plate 94 and the shaft 96 to prevent unwanted liquid migration through the second member 78.

[0041] The flow guide 90 extends axially away from the second member 78 and toward the chamber outlet 72. The flow guide 90 includes a sloped edge extending from a base to a tip. In the illustrated example, the sloped edge is concave. The flow guide 90 is disposed coaxially with the chamber outlet 72. The flow guide 90 is disposed coaxially with the regulator axis A-A. The flow guide 90 extends into the seat 82 such that a portion of the flow guide 90 is within the seat 82 below a top edge of the seat 82. The flow guide 90 extending below the top edge of the seat 82 forms an interference that inhibits uninterrupted radial flow through the seat 82. Instead, liquid flowing into the annular restriction 102 on one side of the seat 82 encounters the flow guide 90 before reaching the center of the seat 82. The flow guide 90 thereby prevents undesirable collisions between opposing flows through the annular restriction 102, as discussed in more detail below. In the illustrated example, the flow guide 90 is integrally formed with the shaft 96. However, it should be understood that the flow guide 90 can be formed in any desired manner. In some examples, the flow guide 90 can be separately formed and connected to the shaft 96, etc. For example, the flow guide 90 can be connected to the shaft 96 by an interface thread, etc. In the illustrated example, the base of the flow guide 90 forms a flange that interfaces with the lower plate 92 such that the nut 98, shaft 96, and flow guide 90 clamp the lower plate 92, second membrane 100, and upper plate 94 together.

[0042] The flow chamber 46 is formed within the pressure housing 40 and is at least partially bounded by the second member 78. The regulator inlet 60 is formed by the pressure housing 40 and is disposed upstream of the flow chamber 46. The inlet bore 64 extends between the regulator inlet 60 and the chamber inlet 70. The regulator outlet 62 is formed by the pressure housing 40 and is disposed downstream of the flow chamber 46. Liquid enters the flow chamber 46 at the chamber inlet 70 and exits the flow chamber 46 at the chamber outlet 72. The chamber inlet 70 is disposed at a forward end 66 of the flow chamber 46. The forward end 66 is disposed at an upstream end of the flow chamber 46. A rearward end 68 is disposed at a downstream end of the flow chamber 46. Side passages 74a, 74b extend between the forward end 66 and the rearward end 68. As discussed in more detail below, each side passage 74a, 74b curves around the chamber outlet 72 and the reservoir axis A-A.

[0043] The side passages 74a, 74b are substantially similar. The side passages 74a, 74b extend between the forward end 66 and the rearward end 68. In some examples, the side passages 74a, 74b can be mirror images of one another disposed on opposite lateral sides of the upstream ridge 56 and the downstream ridge 58.

[0044] For each side passage 74a, 74b, an inner wall 48 is disposed radially inward of the flow chamber 46. The inner wall 48 is inclined between the base wall 52a, 52b and the regulator shelf 54. The inner wall 48 is inclined such that a distance between the reservoir axis A-A at an interface between the inner wall 48 and the base wall 52a, 52b and the inner wall 48 is greater than a distance between the reservoir axis A-A at an interface between the inner wall 48 and the regulator shelf 54. The side passages 74a, 74b are inclined such that a vertical height of the inner wall 48 decreases between the front end 66 and the rear end 68.

[0045] The base wall 52a, 52b extends between the front end 66 and the rear end 68. The base wall 52a, 52b is inclined between the front end 66 and the rear end 68. A vertical height of the flow chamber 46 between the base wall 52a, 52b and the second member 78 decreases in a downstream direction between the chamber inlet 70 and the rear end 68. An inner radial side of each base wall 52a, 52b interfaces with the inner wall 48 and an outer radial side interfaces with the outer wall 50.

[0046] The outer wall 50 is disposed on an outer radial side of the flow chamber 46. The outer wall 50 can extend generally vertically. The outer wall 50 curves about the reservoir axis A-A between the chamber inlet 70 and the rear end 68.

[0047] An upstream ridge 56 is disposed at an upstream end of the flow chamber 46 and is formed on the inner wall 48. The upstream ridge 56 is a protrusion that extends away from the inner wall 48 and into a flow path through which the BPR 26 passes. The upstream ridge 56 can extend into the flow chamber 46 from upstream of the chamber inlet 70. A downstream ridge 58 is disposed at the rear end 68 of the flow chamber 46. The downstream ridge 58 is a protrusion that extends vertically with respect to the base wall 52a, 52b. The upstream ridge 56 imparts an outward velocity component to liquid flowing into the flow chamber 46 to direct the liquid into the side passages 74a, 74b. The downstream ridge 58 redirects flow at a downstream end of each side passage 74a, 74b to prevent undesired collisions between particles (e.g., metal flakes) within the liquid and to direct the flow toward the annular restriction 102.

[0048] The regulator shelf 54 is disposed opposite the second member 78. The regulator shelf 54 can be a platform formed about the chamber outlet 72. The regulator shelf 54 can be an annular surface. The regulator shelf 54 can include an annular groove configured to receive a seal to interface with the seat 82.

[0049] A seat 82 is connected to the pressure housing 40 and disposed opposite the second member 78. The chamber outlet 72 extends through the seat 82. The seat 82 can be connected to the pressure housing 40 in any desired manner, such as by interface threads, etc. The seat 82 is configured to interface with the second member 78 in the closed state of the BPR 26. The second member 78 is spaced apart from the seat 82 to define an annular restriction 102 and allow flow through the BPR 26.

[0050] The BPR 26 is controlled between a closed state, an active state, and a fully open state. In the closed state, the second member 78 contacts the seat 82 to close the annular flowpath 102 and prevent liquid from exiting the flow chamber 46. In the fully open state, the second member 78 is spaced a maximum distance from the seat 82 to fully open the annular restriction 102. For example, during priming of the BPR 26, working fluid can not be provided to the working fluid chamber 44, such that pressure in the flow chamber 46 causes the BPR 26 to transition to fully open. In the active state, working fluid pressure and actual liquid pressure balance on the pressure control mechanism 38, such that the annular restriction 102 opens to an extent between fully closed and fully open. The extent to which the annular restriction 102 opens varies depending on the flow rate through the BPR 26.

[0051] During operation, working fluid is provided to the working fluid chamber 44. The working fluid exerts a first force on the first member 76 that biases the first member 76 downward toward the pressure housing 40. The liquid pressure in the flow chamber 46 exerts a second force on the second member 78 that biases the second member 78 upward toward the control housing 42. The working fluid and the spray liquid exert opposing forces on the first member 76 and the second member 78, respectively, toward the regulator shaft 80. The opposing forces balance to maintain the annular restriction 102 to a desired size to match the actual liquid pressure to the desired liquid pressure. The working fluid pressure is set such that the actual liquid pressure in the flow chamber 46 (and thus upstream of the BPR 26) is maintained at the desired liquid pressure. The size of the annular restriction 102 varies with changes in flow rate through the BPR 26 to maintain the actual liquid pressure at the desired liquid pressure.

[0052] The spray liquid enters the BPR 26 through the regulator inlet 60. The coating flows downstream through the inlet aperture 64 and encounters the upstream ridge 56. The upstream ridge 56 directs the inlet flow into the side channels 74a, 74b. The liquid enters the flow chamber 46 through the chamber inlet 70 and flows through each of the side channels 74a, 74b. The liquid flow encircles the chamber outlet 72 and the seat 82. The inner wall 48 is angled toward the seat 82 and the chamber outlet 72 such that the liquid is directed toward the chamber outlet 72 as the coating flows circumferentially around the chamber outlet 72. The curvature of the outer wall 50 and the base walls 52a, 52b promotes equal flow around the chamber outlet 72. The smooth profile inner wall 48, base walls 52a, 52b, and outer wall 50 promote laminar flow within the flow chamber 46. The portion of the flow of the liquid through the side channels 74a, 74b to the back end 68 encounters the downstream ridge 58. The downstream ridge 58 prevents the two flows from colliding at the back end 68 of the flow chamber 46. The downstream ridge 58 thereby prevents unwanted collisions between the flows at the downstream ends of the side channels 74a, 74b.

[0053] The liquid flow circumferentially encircles the seat 82 and flows to and through the annular restriction 102. The liquid enters the annular restriction 102 from the circumferential perimeter of the seat 82. The flow of liquid entering the annular restriction 102 is evenly distributed circumferentially around the annular restriction 102. Thus, the liquid is evenly distributed as it flows through the annular restriction 102 and to the chamber outlet 72. The height of the side channels 74a, 74b between the front end 66 and the back end 68 is reduced to maintain equal radial flow to the annular restriction 102 as the liquid exits the flow chamber 46 from around the annular restriction 102. The profile of the pressure housing 40 promotes equal radial flow through the annular restriction 102.

[0054] The flow director 90 extends through the seat 82 into the opening such that the distal end of the flow director 90 is disposed below the upper surface of the seat 82, which partially defines the annular restriction 102. The flow director 90 reorients the radial flow of liquid through the annular restriction 102 to a substantially axial flow through the chamber outlet 72. The flow director 90 suppresses turbulent flow and prevents internal collisions between the radial flows. The annular restriction 102 between the flow director 90 and the seat 82 is gradually widened to maintain the velocity of the flow through the annular restriction 102 by preventing sudden deceleration that can cause turbulent flow and collisions within the liquid.

[0055] The coating exits the flow chamber 46, the annular restriction 102, and the chamber outlet 72, and exits the BPR 26 through the regulator outlet 62. The coating flows downstream from the BPR 26 and can continue to circulate in the system. The force exerted by the coating on the second member 78 varies with changes in the flow rate through the BPR 26. The forces exerted by the working fluid and the spray liquid are balanced on the pressure control mechanism 38 such that the area of flow through the annular restriction 102 varies with changes in the actual liquid pressure. These changes maintain the actual liquid pressure at the desired liquid pressure at various volumetric flow rates.

[0056] The BPR 26 provides significant advantages. The geometry and profile of the pressure housing 40 provide a smooth flow of the liquid within the flow chamber 46. The geometry and profile distribute the flow evenly circumferentially around the chamber outlet 72 and reduce shear of the spray liquid. The evenly distributed flow provides better control of the actual liquid pressure and faster reaction to changes in flow rate. Thus, the BPR 26 maintains the actual liquid pressure at the desired liquid pressure at various flow rates. The smoothly changing profile of the pressure housing 40 also facilitates purging of the flow chamber 46 and prevents shear of the spray liquid. The profile eliminates dead zones within the flow chamber 46 where particles and solids can accumulate, which can be detrimental to the components and operation of the BPR 26. The BPR 26 prevents the accumulation of potentially harmful solids and can be purged more quickly, thereby reducing the amount of solvent required to purge the coating from the BPR 26 during a change in coating color or change of the BPR 26. The BPR 26 also prevents undesirable impingement within the coating. Such impingement can damage the coating, such as by damaging the metal flakes (e.g., bending, breaking, deforming, etc.), which can change the color of the coating. The downstream ridge 58 prevents impingement at the back end 68 when the coating exits each of the side passages 74a, 74b, and the flow director 90 prevents impingement when the coating flows into the chamber outlet 72. Preventing impingement inhibits degradation, thereby maintaining the desired properties of the coating. Thus, the coating can be circulated for a longer period of time without experiencing undesirable degradation. Increasing the circulation life of the coating reduces the cost and downtime of the system.

[0057] Figure 4 is Figure 3CFIG. 4 is an enlarged view of detail 4 in FIG. 3. The pressure housing 40, the second member 78, the seat 82, and the annular restriction 102 are shown. The regulator shelf 54 and the chamber outlet 72 of the pressure housing 40 are shown. The flow director 90 and the lower plate 92 of the second member 78 are shown. The flow director 90 includes a base end 104, a flow director side 106, and a distal end 108. The seat 82 includes a top portion 110, a lower portion 112, an outer edge 114, a top surface 116, a transition surface 118, and an inner surface 120. The annular restriction 102 includes a restriction inlet 128, a restriction outlet 130, an upstream portion 132, and a downstream portion 134.

[0058] The seat 82 is mounted to the pressure housing 40. The top portion 110 extends radially outward relative to the lower portion 112. The lower portion 112 extends generally axially relative to the regulator axis A-A. The lower portion 112 of the seat 82 extends into the outlet aperture 126 formed in the pressure housing 40. The lower portion 112 interfaces with the pressure housing 40 to secure the seat 82 to the pressure housing 40. For example, the lower portion 112 and the outlet aperture 126 can include interface threads to secure the lower portion 112 to the pressure housing 40. However, it should be understood that the seat 82 can be connected to the pressure housing 40 in any desired manner, such as by a press-fit connection, an adhesive, etc. The chamber outlet 72 is at least partially defined by the seat 82. The seal groove 122 extends into the regulator shelf 54 of the pressure housing 40. The seal 124 is disposed in the seal groove 122. The seal 124 prevents spray liquid in the flow chamber 46 from leaking from the flow chamber 46 to the outlet aperture 126 between the seat 82 and the pressure housing 40. Liquid in the flow chamber 46 can only exit the flow chamber 46 through the annular restriction 102. Although the seal groove 122 is shown as being formed in the pressure housing 40, it should be understood that in some examples the seal groove 122 is formed in the seat 82.

[0059] The outer edge 114 forms a radially outermost portion of the seat 82. The outer edge 114 is disposed about the top portion 110. In the example shown, the outer edge 114 extends generally vertically. As Figure 5A As best seen in FIG. 4, the outer edge 114 can include a profile that circumferentially surrounds the seat 82. In some examples, the outer edge 114 can be a smooth surface that circumferentially surrounds the seat 82. In some examples, at least a portion of the outer edge 114 can be spaced apart from an edge of the regulator shelf 54, where the regulator shelf 54 interfaces with the inner wall 48.

[0060] The top surface 116 at least partially defines the annular restriction 102. The top surface 116 is disposed opposite the lower plate 92 such that a gap between the top surface 116 and the lower plate 92 forms at least a portion of the annular restriction 102. The top surface 116 has a width TW. In some examples, the width TW can be between about 12.07 millimeters (mm) (about 0.475 inches (In.)) and about 18.29 mm (about 0.72 inches). The seat 82 has a radius SR. The seat radius SR can be between about 18.29 (mm) (about 0.73 inches) and about 25.4 mm (about 1 inch). In some examples, a ratio of the width TW to the radius SR can be between about 0.5: 1 and about 1.25: 1. More specifically, the ratio of the width TW to the radius SR can be between about 0.65: 1 and 0.7: 1. The ratio of the width to the radius of the seat 82 facilitates a steady radial velocity of the flow of liquid through the annular restriction 102. The ratio of the width to the radius of the seat 82 prevents sudden changes in velocity that can create turbulent flow and result in degradation of the spray liquid.

[0061] The inner surface 120 is formed on the lower portion 112 and extends substantially vertically. The transition surface 118 extends between and connects the top surface 116 and the inner surface 120. The transition surface 118 is a curved surface that provides a smooth transition between the top surface 116 and the inner surface 120. The transition surface 118 is convexly curved to provide the smooth transition. The transition surface 118 is disposed opposite the flow guide side 106. Portions of the transition surface 118 can be spaced apart from portions of the flow guide side 106 when the BPR 26 is in the activated state and when the BPR 26 is in the closed state.

[0062] The second member 78 is configured to move relative to the seat 82 to change a size of the annular restriction 102. The lower plate 92 is disposed opposite the top surface 116. The lower plate 92 at least partially defines the annular restriction 102. The flow guide 90 protrudes from the second member 78 into the seat 82. The flow guide 90 extends protrudes from the lower plate 92 and into the chamber outlet 72. The flow guide 90 extends through an opening defined by the top surface 116 and into the seat 72. The flow guide 90 is disposed on the regulator axis A-A. The flow guide 90 is disposed coaxially with the seat 82. In some examples, the flow guide 90 can be conical. In some examples, the flow guide 90 can be bell-shaped.

[0063] The base end 104 of the flow guide 90 is disposed at the lower plate 92. The base end 104 can form a flange configured to interface with the lower plate 92 to clamp the components of the second member 78 together. The flow guide side 106 extends between the base end 104 and a distal end 108. The flow guide side 106 is an inclined surface that extends between the base end 104 and the distal end 108. In the example shown, the flow guide side 106 is a concave curved surface that extends in an annular fashion around the flow guide 90. In the example shown, the distal end 108 is a rounded tip. However, it should be understood that other configurations of the distal end 108 are possible. During operation, the distal end 108 is disposed within the seat 82. The distal end 108 extends through the seat 82 into the opening such that the distal end 108 is disposed axially below the top surface 116. In some states, the distal end 108 can extend axially beyond the transition surface 118. Thus, with the BPR 26 in the activated state, at least a portion of the flow guide 90 can axially overlap at least a portion of the inner surface 120 along the restrictor axis A-A. With the BPR 26 in the activated state, the flow guide 90 can axially overlap the entire extent of the transition surface 118. With the BPR 26 in the activated state, the flow guide 90 can partially axially overlap the transition surface 118 without axially overlapping the inner surface 120.

[0064] An annular restriction 102 is formed between the second member 78 and the seat 82. The annular restriction 102 forms a flow path for the spray liquid to exit the flow chamber 46 and flow downstream from the BPR 26. The annular restriction 102 extends between a restriction inlet 128 and a restriction outlet 130. The annular restriction 102 has an upstream portion 132 and a downstream portion 134. The height of the gap between the seat 82 and the second member 78 is uniform within the upstream portion 132. The gap between the seat 82 and the second member 78 remains constant along the width of the upstream portion 132 between an upstream end of the upstream portion 132 and a downstream end of the upstream portion 132. The upstream portion 132 can also be referred to as a uniform portion. The gap between the seat 82 and the second member 78 changes within the downstream portion 134 and widens between an upstream end of the downstream portion 134 and a downstream end of the downstream portion 134. The downstream portion 134 can also be referred to as a variable portion. In some examples, the transition surface 118 has a first radius of curvature and the flow guide side 106 has a second radius of curvature that is different than the first radius of curvature. The second radius of curvature is greater than the first radius of curvature. In some examples, the radius of curvature of the transition surface 118 can vary between an upstream end of the transition surface 118 and a downstream end of the transition surface 118. In some examples, the radius of curvature of the flow guide side 106 can vary between the base end 104 and the distal end 108. In some examples, the radius of curvature of the flow guide side 106 can increase between the base end 104 and the distal end 108. The complementary curvatures of the flow guide side 106 and the transition surface 118 facilitate the turning of the liquid from a radial flow into the annular restriction 102 to an axial flow out of the annular restriction 102. The interface between the flat portion of the second member 78 and the curved portion formed by the flow guide side 106 can be positioned radially closer to the regulator axis A-A than the interface between the flat top surface 116 and the transition surface 118.

[0065] The spray liquid within the flow chamber 46 exerts a force on the second member 78 to bias the second member 78 away from the seat 82, thereby opening the flow path through the annular restriction 102. The spray liquid enters the annular restriction 102 at the restriction inlet 128 and flows through the upstream portion 132. The upstream portion 132 forms the narrowest portion of the flow path through the annular restriction 102. The interface between the flat top surface 116 and the transition surface 118. The upstream portion 132 is the narrowest restriction in the flow path through the BPR 26. Changing the size of the restriction controls the pressure drop and flow rate through the annular restriction 102, thereby controlling the actual liquid pressure in the flow chamber 46 and upstream of the BPR 26. The size of the upstream portion 132 varies with the flow rate through the BPR 26 such that the pressure drop through the annular restriction 102 remains stable at various flow rates. The upstream portion 132 can have the same width TW as the top surface 116. The size of the upstream portion 132 is configured for uniform radial flow through the upstream portion 132 to prevent undesirable degradation. The size of the upstream portion 132 is configured to provide a quick response to changes in flow rate such that the actual liquid pressure remains stable.

[0066] The spray liquid enters the downstream portion 134 of the annular restriction 102 from the upstream portion 132. The downstream portion 134 has a first cross-sectional area at an upstream end, where the downstream portion 134 interfaces with the upstream portion 132, and a second cross-sectional area at the restriction outlet 130. The second cross-sectional area is larger than the first cross-sectional area. The cross-sectional area of the downstream portion 134 expands smoothly between the first cross-sectional area and the second cross-sectional area. The concave curvature of the flow guide side 106 and the convex curvature of the transition surface 118 facilitate a smooth transition from the first cross-sectional area to the second cross-sectional area. The expansion of the downstream portion 134 prevents sudden changes in velocity that can occur due to a sudden increase in cross-sectional area. Controlling the velocity change by gradually opening the cross-sectional area through the annular restriction 102 encourages laminar flow and suppresses turbulent flow, thereby preventing undesirable collisions within the liquid that can cause degradation of the liquid.

[0067] As the coating flows through the annular restriction 102, the spray liquid encounters the flow directors 90. The flow directors 90 are positioned on the regulator axis A-A such that the radial flow encounters the flow directors 90 before reaching the regulator axis A-A. The flow directors 90 divert the spray liquid from a radial flow to an axial flow as the spray liquid flows through the annular restriction 102. The flow directors 90 divert the radial flow entering the annular restriction 102 to an axial flow exiting the annular restriction 102. The concave curvature of the flow director side 106 diverts the spray liquid as it flows through the annular restriction 102. The flow directors 90 divert the radial liquid flow before the flow reaches the regulator axis A-A. The flow directors 90 thereby prevent various radial flows from meeting and colliding. Instead, the flow is gradually diverted such that a substantially axial flow exits the annular restriction 102 at the restriction outlet 130 to combine downstream of the annular restriction 102. The combination of substantially axial flows promotes laminar flow and avoids turbulence and internal collisions that can occur when opposing radial flows converge.

[0068] The second member 78 and the seat 82 provide significant advantages. The annular restriction 102 includes an upstream portion 132 whose cross-sectional area controls and maintains the pressure in the flow chamber 46. The width of the upstream portion 132 promotes precise control of the pressure in the flow chamber 46. Changes in the height of the upstream portion 132 result in gradual changes in the actual liquid pressure in the flow chamber 46. Thus, the position of the second member 78 relative to the seat 82 can fluctuate without causing sudden pressure changes. The annular restriction 102 therefore provides greater and more sensitive control of flow rate changes. The annular restriction 102 maintains the actual liquid pressure as a steady pressure as the flow rate changes between high and low flow rates. The annular restriction 102 includes a downstream portion 134 that gradually widens between the upstream portion 132 and the outlet of the annular restriction 102. The gradual widening of the annular restriction 102 regulates the change in velocity of the liquid flowing through the annular restriction 102, preventing sudden decelerations that can cause turbulence and internal collisions. The flow directors 90 prevent radial flows through the annular restriction 102 from colliding, instead gradually diverting the flow to a generally axial flow that exits the annular restriction 102. Preventing internal collisions can prevent degradation and maintain the desired quality of the spray liquid. For example, internal collisions can damage metal flakes in the coating, which can cause changes in the color of the coating.

[0069] Figure 5A is a cross-sectional view of the BPR 26 taken along line 5A-5A in Figure 3A is a cross-sectional view of the BPR 26 taken along line 5B-5B in Figure 5B is a cross-sectional view of the BPR 26 taken along line 5A-5A in Figure 3B is a cross-sectional view of the BPR 26 taken along line 5B-5B in Figure 5A and Figure 5BThe BPR 26 includes a body 36 and a pressure control mechanism 38. The body 36 includes a pressure housing 40 and a control housing 42. The BPR 26 also includes a working fluid chamber 44 and a flow chamber 46. The pressure housing 40 includes an inner wall 48, an outer wall 50, base walls 52a, 52b, an adjuster shelf 54, an upstream ridge 56, a downstream ridge 58, an adjuster inlet 60, an adjuster outlet 62, and side ridges 63a, 63b. The flow chamber 46 includes a front end 66, a rear end 68, a chamber inlet 70, a chamber outlet 72, and side channels 74a, 74b. The pressure control mechanism 38 includes a first member 76, a second member 78, an adjuster shaft 80, and a seat 82. A first plate 84 and a first diaphragm 86 of the first member 76 are shown. The second member 78 includes a flow director 90, a lower plate 92, an upper plate 94, a shaft 96, a nut 98, and a second diaphragm 100.

[0070] The pressure housing 40 is contoured to distribute a uniform spray liquid flow circumferentially around the seat 82. The pressure housing 40 provides a consistent radial flow rate to and through an annular restriction 102 (best seen in Figure 4 The upstream ridge 56 is disposed at the front end 66 of the flow chamber 46. The upstream ridge 56 is disposed on and extends from the inner wall 48. The upstream ridge 56 can include a sloped wall such that the upstream ridge 56 has a first width at a base of the upstream ridge 56 that is greater than a second width of a top of the upstream ridge 56. The upstream ridge 56 has a sloped side that imparts an outward flow component to the spray liquid to direct the spray liquid to the side channels 74a, 74b. In some examples, the width of the base of the upstream ridge 56 can vary along the length of the upstream ridge 56. For example, the base of the upstream ridge 56 can be narrower at a downstream end than a portion of the upstream ridge 56 upstream of the downstream end.

[0071] In the illustrated example, an upstream end of the upstream ridge 56 is disposed in the flow path between the adjuster inlet 60 and the chamber inlet 70, and a downstream end of the upstream ridge 56 is disposed within the flow chamber 46 proximate the interface between the inner wall 48 and the adjuster shelf 54. In some examples, the downstream end of the upstream ridge 56 is spaced apart from the interface between the inner wall 48 and the adjuster shelf 54 along the inner wall 48. Thus, the downstream end of the upstream ridge 56 can terminate at the inner wall 48 and be spaced apart from the interface between the inner wall 48 and the adjuster shelf 54.

[0072] The side passages 74a, 74b extend in an arcuate manner around the chamber outlet 72. The side passages 74a, 74b loop around the chamber outlet 72 between the front end 66 and the rear end 68. The side passage 74a is defined at least in part by the inner wall 48, the base wall 52a, and the outer wall 50. The side passage 74b is defined at least in part by the inner wall 48, the base wall 52b, and the outer wall 50. The inner wall 48 is a sloped wall that narrows between the base of the flow chamber 46 and the regulator shelf 54. The inner wall 48 is sloped to direct the paint toward the chamber outlet 72. The outer wall 50 extends circumferentially around the flow chamber 46 and at least partially defines each side passage 74a, 74b. The outer wall 50 is a curved wall. The base walls 52a, 52b curve around the inner wall 48. The base walls 52a, 52b define a base end of each side passage 74a, 74b, respectively. The volume of liquid within the side passages 74a, 74b decreases between the upstream end and the downstream end of the side passages 74a, 74b as the liquid exits through the annular restriction 102. The base walls 52a, 52b slope between the front end 66 and the rear end 68 such that the height of each side passage 74a, 74b decreases between the front end 66 and the rear end 68. The decreasing height of each side passage 74a, 74b decreases the area of flow of each side passage 74a, 74b from the upstream end to the downstream end. The decreasing area of flow maintains the pressure and velocity as the liquid exits circumferentially from the flow chamber 46 around the chamber outlet 72.

[0073] A downstream ridge 58 is disposed at the rear end 68 of the flow chamber 46. The downstream ridge 58 is disposed between and separates the downstream ends of the side passages 74a and 74b. The downstream ridge 58 is a protrusion disposed between the base walls 52a, 52b. The downstream ridge 58 extends between the regulator shelf 54 and the outer wall 50. The downstream ridge 58 extends between the regulator shelf 54 and the portion of the outer wall 50 disposed at the rear end 68 of the flow chamber 46. The downstream ridge 58 includes a sloped side such that the downstream ridge 58 has a first width at the base of the downstream ridge 58 that is greater than a second width of the top of the downstream ridge 58. The sloped side diverts the spray liquid at the downstream end of each side passage 74a, 74b. The downstream ridge 58 prevents the spray liquid exiting the side passage 74a from colliding with the spray liquid exiting the side passage 74b, which can cause paint damage and degradation of the paint. The profile of the downstream ridge 58 is configured to divert the spray liquid flow to direct the spray liquid flow toward the annular restriction 102. The downstream ridge 58 encourages substantially equal flow from the circumferential perimeter of the annular restriction 102 into the annular restriction 102.

[0074] The upstream ridge 56 can extend axially between an upstream end and a downstream end of the upstream ridge 56. The side ridges 63a, 63b are disposed on opposite lateral sides of the upstream ridge 56. The side ridges 63a, 63b each help direct flow to the side channels 74a, 74b. In some examples, the side ridges 63a, 63b can be formed on and extend from the upstream ridge 56. The side ridges 63a, 63b can have a shorter axial length than the upstream ridge 56. The upstream ridge 56 can further project into the flow path between the regulator inlet 60 and the chamber inlet 70 than the side ridges 63a, 63b.

[0075] In the illustrated example, the upstream ridge 56 is disposed on a first ridge axis R1-R1. The first ridge axis R1-R1 can intersect the regulator axis A-A. The first ridge axis R1-R1 is transverse to the regulator axis A-A. The first ridge axis R1-R1 can be non-orthogonal to the regulator axis A-A. The first ridge axis R1-R1 can intersect the regulator axis A-A at a location outside the flow chamber 46. The downstream ridge 58 can extend axially between an inner end and an outer end of the downstream ridge 58. In the illustrated example, the downstream ridge 58 is disposed on a second ridge axis R2-R2. The second ridge axis R2-R2 can intersect the regulator axis A-A. The second ridge axis R2-R2 is transverse to the regulator axis A-A. In some examples, the second ridge axis R2-R2 can be orthogonal to the regulator axis A-A. In some examples, the second ridge axis R2-R2 can be non-orthogonal to the regulator axis A-A. The second ridge axis R2-R2 can intersect the regulator axis A-A at a location outside the flow chamber 46. In the illustrated example, the second ridge axis R2-R2 intersects the regulator axis A-A at a location within the seat 82, which can be within or below the annular restriction 102. The first ridge axis R1-R1 can be disposed transverse to the second ridge axis R2-R2. The first ridge axis R1-R1 can be non-orthogonal to the second ridge axis R2-R2.

[0076] During operation, the spray liquid enters the pressure housing 40 through the regulator inlet 60. The coating flows through the inlet hole 64 and encounters the upstream ridge 56. The upstream ridge 56 divides the coating into lateral flows that flow to the side passages 74a, 74b. The flow of coating encounters the upstream ridge 56 within the inlet hole 64 at a location upstream of the chamber inlet 70. The upstream ridge 56 imparts an outward velocity component to the flow to direct the spray liquid to the side passages 74a, 74b. A first sub-flow flows to and through the side passage 74a, and a second sub-flow flows to and through the side passage 74b. These sub-flows flow through the side passages 74a, 74b to the back end 68 and the downstream ridge 58. The downstream ridge 58 reorients these sub-flows to prevent impingement at the back end 68 and to direct the flow toward the annular restriction 102. The spray liquid flows up the side passages 74a, 74b and along the inner wall 48 at the back end 68 to the annular restriction at the front end 66. The contouring of the pressure housing 40 provides a uniform radial flow from the circumferential perimeter of the annular restriction 102 through the annular restriction 102.

[0077] The BPR 26 provides significant advantages. The upstream ridge 56 imparts an outward velocity component to the spray liquid that directs the spray liquid into and along the side passages 74a, 74b. The upstream ridge 56 is angled to impart the outward velocity component. This angled transition prevents impingement between the coating and the pressure housing 40 that can cause degradation of the coating and accumulation of solids. The spray liquid flows through the side passages 74a, 74b and around the annular restriction 102 and the chamber outlet 72. The side passages 74a, 74b are angled between the front end 66 and the back end 68 such that the height between the base walls 52a, 52b and the second member 78 decreases between the front end 66 and the back end 68 to maintain flow velocity and pressure throughout the side passages 74a, 74b. The inner wall 48 is angled toward the annular restriction 102 to direct the spray liquid from the circumferential perimeter of the annular restriction 102 toward the annular restriction 102. The angled configuration of the side passages 74a, 74b maintains flow velocity and pressure as the coating flows through the side passages 74a, 74b. The contouring of the pressure housing 40 directs the spray liquid toward the annular restriction 102 with a uniform radial flow velocity from the circumferential perimeter of the annular restriction 102. The downstream ridge 58 reorients the coating at the downstream end of each side passage 74a, 74b to direct the flow toward the annular restriction 102, further providing a uniform radial velocity around the annular restriction 102. The downstream ridge 58 also prevents impingement between the flows at the downstream end of the side passages 74a, 74b, preventing degradation.

[0078] Consistent radial flow rates inhibit vortices and other turbulence in the spray liquid, thereby avoiding internal collisions that can cause degradation. Preventing degradation increases user confidence, providing longer useful life for the circulating liquid, thereby reducing cost and downtime. Consistent flow also helps to maintain actual liquid pressure as a desired liquid pressure at various flow rates. Maintaining actual liquid pressure as a desired liquid pressure at various flow rates provides improved spray consistency and spray quality. The contoured construction of the pressure housing 40 provides smooth flow throughout the flow chamber 46, thereby preventing dead zones that can cause solids to accumulate. Consistent flow also promotes efficient flushing of the flow chamber 46, thereby reducing the time required for flushing, simplifying the flushing process, and reducing the amount of material required for flushing.

[0079] Figure 6A is a cross-sectional view of the BPR 26, showing flow lines FL of the spray liquid through the flow chamber 46. Figure 6B is a side view of the flow chamber 46, showing flow lines FL of the spray liquid through the flow chamber 46. Figure 6C is a top view of the flow chamber 46, showing flow lines FL of the spray liquid through the flow chamber 46. Figures 6A to 6C will be discussed together. The spray liquid enters the flow chamber 46 at the chamber inlet 70. The upstream ridge 56 separates the spray liquid flow and imparts an outward velocity component to the spray liquid to cause the spray liquid to flow into the side passages 74a, 74b. The spray liquid flows up the inner wall 48 toward the annular restriction 102 and the chamber outlet 72. The spray liquid enters the annular restriction 102 (best seen in Figure 4 ) and flows radially through the annular restriction 102. The pressure housing 40 promotes equal spray liquid flow circumferentially around the annular restriction 102 into the annular restriction 102. As the spray liquid flows downstream through the side passages 74a, 74b, the volume of spray liquid within the side passages 74a, 74b decreases as the coating passes through the annular restriction 102 out of the side passages 74a, 74b and the flow chamber 46. The angled side passages 74a, 74b maintain consistent flow and pressure by reducing the area of flow between the upstream end and the downstream end of the side passages 74a, 74b in correspondence with the coating exiting the flow chamber 46. The downstream ridge 58 reorients the flow at the downstream end of each side passage 74a, 74b toward the annular restriction 102, thereby further promoting consistent radial flow circumferentially around the annular restriction 102 to the annular restriction 102.

[0080] The flow chamber 48 can be considered to be divided into quadrants. A first quadrant Ql and a second quadrant Q2 define an upstream half of the flow chamber 48. A third quadrant Q3 and a fourth quadrant Q4 define a downstream half of the flow chamber 48. Thus, the first quadrant Ql and the second quadrant Q2 are disposed between the midpoint of the chamber outlet 72 and the chamber inlet 70, while the third quadrant Q3 and the fourth quadrant Q4 are disposed between the horizontal line through the axis A-A and the back end 68 of the flow chamber 48. The quadrant Q3 is divided into an upstream sector USl and a downstream sector DS 1. The quadrant Q4 is similarly divided into an upstream sector US2 and a downstream sector DS2.

[0081] During operation, the BPR 26 promotes consistent radial flow into the annular restriction 102 from the circumferential perimeter of the annular restriction 102. In some examples, more than about 35% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream half formed by the third quadrant Q3 and the fourth quadrant Q4. In some examples, more than about 40% of the flow exits the flow chamber 46 and enters the annular restriction 102 through the downstream half formed by the third quadrant Q3 and the fourth quadrant Q4. In some examples, more than about 45% of the flow exits the flow chamber 46 and enters the annular restriction 102 through the downstream half. In some examples, between about 35% and 50% of the flow exits the flow chamber 46 and enters the annular restriction 102 through the downstream half. In some examples, between about 40% and 50% of the flow exits the flow chamber 46 and enters the annular restriction 102 through the downstream half. In some examples, the ratio of spray liquid exiting the flow chamber 46 from the upstream half and the downstream half can be about 1 : 1. In some examples, the ratio of spray liquid exiting the flow chamber 46 from the upstream half and the downstream half can be about 11 : 9. In some examples, the ratio of spray liquid exiting the flow chamber 46 from the upstream half and the downstream half can be about 3 : 2. In some examples, the ratio of spray liquid exiting the flow chamber 46 from the upstream half and the downstream half can be more balanced than a ratio of about 7 : 3. In some examples, the ratio of spray liquid exiting the flow chamber 46 from the upstream half and the downstream half can be more balanced than a ratio of about 2 : 1.

[0082] The flow can exit the flow chamber 46 in equal proportions through both sides of the flow chamber 46. For example, the proportion of flow exiting through the first quadrant Ql and the third quadrant Q3 can be equal to the proportion of flow exiting through the second quadrant Q2 and the fourth quadrant Q4.

[0083] In some examples, at least about 15% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the third quadrant Q3. In some examples, at least about 20% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the third quadrant Q3. In some examples, at least about 22.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the third quadrant Q3. In some examples, about 15-25% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the third quadrant Q3. In some examples, about 20-25% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the third quadrant Q3.

[0084] In some examples, more than about 10% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US1. In some examples, about 10-15% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US1. In some examples, about 12.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US1. In some examples, at most about 15% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US1.

[0085] In some examples, more than about 5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS1. In some examples, more than about 7.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS1. In some examples, about 7.5-12.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS1. In some examples, about 10% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS1.

[0086] In some examples, at least about 15% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the fourth quadrant Q4. In some examples, at least about 20% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the fourth quadrant Q4. In some examples, at least about 22.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the fourth quadrant Q4. In some examples, about 15-25% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the fourth quadrant Q4. In some examples, about 20-25% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the fourth quadrant Q4.

[0087] In some examples, more than about 10% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US2. In some examples, about 10-15% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US2. In some examples, about 12.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US2. In some examples, at most about 15% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the upstream section US2.

[0088] In some examples, more than about 5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS2. In some examples, more than about 7.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS2. In some examples, about 7.5-12.5% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS2. In some examples, about 10% of the flow exits the flow chamber 46 and enters the annular restriction 102 from the downstream section DS2.

[0089] The consistent, balanced radial flow into the annular restriction 102 suppresses vortices and other turbulence in the spray liquid, avoiding internal impingements that can cause degradation. The contouring of the flow chamber 46 prevents the formation of dead spots that can cause solids to accumulate. Thus, the contouring of the pressure housing 40 promotes flushing of the flow chamber 46 and consistent flow through the flow chamber 46. The consistent flow circumferentially into the annular restriction 102 also promotes a consistent velocity of the spray liquid, preventing undesirable velocity changes that can cause turbulence and degradation. The spray liquid circumferentially into the annular restriction 102 around the annular restriction 102 promotes a quick reaction to changes in flow through the BPR 26. Thus, the BPR 26 reacts more quickly to changes in volumetric flow through the BPR 26 and provides a consistent actual liquid pressure within the flow chamber 46. The quick reaction to flow changes prevents undesirable pressure spikes and changes. Thus, the BPR 26 maintains a stable actual liquid pressure throughout operation when the flow through the BPR 26 changes, which maintains a consistent velocity through the annular restriction 102 and prevents undesirable turbulence and internal impingements that can cause degradation. Maintaining a consistent actual liquid pressure provides a uniform spray quality and pattern at the sprayer upstream of the BPR 26. The uniform spray pattern and spray pressure provides consistency between multiple applications, providing a high quality, uniform polish that both users and consumers desire.

[0090] Figure 7 is a cross-sectional view of a BPR 26'. The BPR 26' is substantially similar to the BPR 26 Figure 1 、 Figures 3A to 6C), except that the BPR 26' mechanically biases the pressure control mechanism 38 toward the closed state, while the BPR 26 fluidically biases the pressure control mechanism 38' toward the closed state.

[0091] The pressure control mechanism 38' is substantially similar to the pressure control mechanism 38, except that the pressure control mechanism 38' includes a control pin 136, a control plate 138, and a control spring 140. The control pin 136 is movable relative to the control housing 42 to adjust the position of the control plate 140 within the control housing 42. Changing the position of the control plate 140 changes the compression of the control spring 142 to control the back pressure upstream of the BPR 26'. For example, the control pin 136 can be threadably mounted to the control housing 42 and can be rotated between various pressure control positions.

[0092] The control spring 142 extends into and interfaces with the upper plate 94. The shaft 96 and the nut 98 can extend into the control spring 142 to position the control spring 142 on the second member 78. The control spring 142 can be sized such that the diameter of the control spring 142 overlaps the top surface 116. Sizing the control spring 142 to make such an overlap facilitates a uniform change in the gap forming the upstream portion 132. The uniform change maintains a steady flow of fluid through the annular restriction 102 from the circumferential perimeter of the annular restriction 102, thereby preventing the formation of turbulent flow and providing a steady back pressure at various flow rates.

[0093] Figure 8 is a graph showing the inlet pressure of a back pressure regulator (such as the BPR 26 and the BPR 26') versus flow rate. The vertical axis is inlet pressure in pounds per square inch (psi). The horizontal axis is flow rate in gallons per minute (gpm). The line LI shows the pressure curve for the actual liquid pressure in the flow chamber 46 of the BPR 26. In the illustrated embodiment, the desired liquid pressure is set to 150 psi (about 1.03 megapascals (MPa)).

[0094] The actual liquid pressure is measured at various flow rates through the BPR 26. As discussed above, the opening through the annular restriction 102 changes as the flow rate changes to maintain a stable actual liquid pressure in the flow chamber 46 relative to the desired liquid pressure. The BPR 26, 26' maintains the actual liquid pressure within ten percent of the desired liquid pressure. In some examples, the BPR 26, 26' maintains the liquid pressure within about five percent of the desired liquid pressure. At an inlet pressure of about 0.2 gpm (about 0.76 liters per minute (lpm)), the actual liquid pressure is about 142.3 psi (about 0.98 MPa). At an inlet pressure of about 10 gpm (about 37.85 lpm), the actual liquid pressure is about 154.2 psi (about 1.06 MPa). As shown, the actual liquid pressure increases as the flow rate increases. The rate of change of the actual liquid pressure can vary with flow rate. The rate of change of the actual liquid pressure decreases as the flow rate increases. In some examples, the actual liquid pressure changes less than about 1.5 psi for each 1 gpm change in flow rate. In some examples, for at least a portion of the flow rate changes, the actual liquid pressure changes less than about 1 psi for each 1 gpm change in flow rate. In the example shown, between a flow rate of 1 gpm and 10 gpm, the actual liquid pressure changes about 0.85 psi for each 1 gpm change. Between a flow rate of 5 gpm and 10 gpm, the actual liquid pressure changes about 0.74 psi for each 1 gpm change. Between a flow rate of 7.5 gpm and 10 gpm, the actual liquid pressure changes about 0.68 psi for each 1 gpm change. While the example shown is for a desired liquid pressure of about 150 psi (about 1.03 MPa), it is understood that the BPR 26, 26' can provide similar advantages at various desired liquid pressures. The BPR 26, 26' maintains the actual liquid pressure close to the desired liquid pressure at various flow rates, ensuring that the sprayers upstream of the BPR 26, 26' produce a uniform spray pattern, providing consistent application and polishing quality.

[0095] While the application has been described with respect to the exemplary embodiments thereof, those skilled in the art will understand that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the application. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from the essential scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this application, but that the application will include all embodiments falling within the scope of the appended claims.

Claims

1. A back pressure regulator comprising: a pressure housing having an outer wall, an inner wall; a flow chamber at least partially defined by the pressure housing, the flow chamber including a chamber inlet through the pressure housing and a chamber outlet through the pressure housing, wherein the flow chamber extends circumferentially around the chamber outlet; an upstream ridge projecting from the inner wall and into the fluid chamber, the upstream ridge elongated along a ridge axis, the ridge axis extending in a flow direction between the chamber inlet and chamber outlet, and a pressure control member at least partially defining the flow chamber, wherein the pressure control member includes a flow guide disposed on a regulator axis and configured to extend at least partially into the chamber outlet; wherein the inner wall is inclined between a lower end and an upper end; and wherein the pressure control member is movable between a closed state during which the chamber outlet is closed and an activated state during which an annular restriction between the flow chamber and the chamber outlet is open.

2. The back pressure regulator of claim 1, further comprising: a first side passage extending between the chamber inlet and a rear end of the flow chamber; and a second side passage extending between the chamber inlet and the rear end; wherein the first side passage and the second side passage curve around the chamber outlet.

3. The back pressure regulator of claim 2, wherein, The first side passage has a sloped base such that a height of the first side passage decreases between the chamber inlet and the rear end.

4. The back pressure regulator of claim 3, wherein, The inner wall is inclined between the sloped base and a shelf, and wherein the chamber outlet extends through the shelf.

5. The back pressure regulator of claim 2, further comprising: a downstream ridge disposed at the rear end between a first downstream end of the first side passage and a second downstream end of the second side passage.

6. The back pressure regulator of claim 1, wherein, The ridge axis is transverse to the regulator axis.

7. The back pressure regulator of claim 1, further comprising: a downstream ridge disposed at a rear end of the flow chamber.

8. The back pressure regulator of claim 7, wherein, The upstream ridge has an inclined side and the downstream ridge has an inclined side.

9. The back pressure regulator of claim 1, wherein, The upstream ridge extends through the chamber inlet into a flow path between a regulator inlet and the chamber inlet.

10. The back pressure regulator of claim 1, wherein, A profile of the upstream ridge is configured to direct flow into a first side passage and a second side passage, wherein the first side passage and the second side passage curve around the inner wall.

11. The back pressure regulator of claim 5, wherein, A profile of the downstream ridge is configured to direct flow from the first side passage and the second side passage to the chamber outlet, wherein the first side passage and the second side passage curve around the inner wall.

12. The back pressure regulator of any of claims 1-5, further comprising: a seat mounted to the pressure housing, wherein the chamber outlet extends through the seat; wherein the pressure control member and the seat define the annular restriction therebetween; and wherein the annular restriction provides a flow path between the flow chamber and the chamber outlet.

13. The back pressure regulator of claim 12, wherein, The seat includes: a top portion disposed on an adjuster shelf formed at a top end of the inner wall; a lower portion extending into the pressure housing; a top surface formed on the top portion and oriented toward the pressure control member; an inner surface formed on a radially inner side of the lower portion; and a transition surface extending between and connecting the top surface and the inner surface, wherein the transition surface is curved.

14. The back pressure regulator of claim 13, wherein, A ratio between a width of the top surface and a radius of the seat is between 0.65:1 and 0.75:1, inclusive.

15. The back pressure regulator of claim 13, wherein, The flow director includes a contoured side extending between a base and a distal end.

16. The back pressure regulator of claim 15, wherein, The contoured side is concavely curved.

17. The back pressure regulator of claim 16, wherein, The annular restriction includes an upstream portion extending from a restriction inlet and a downstream portion extending between the upstream portion and a restriction outlet.

18. The back pressure regulator of claim 17, wherein, The upstream portion has a uniform cross-sectional area and the downstream portion has a variable cross-sectional area.

19. The back pressure regulator of claim 17, wherein, The downstream portion widens between the upstream portion and the adjuster outlet.

20. The back pressure regulator of claim 1, wherein, The flow director includes a base, a distal end, and a flow director side extending between the base and the distal end, wherein the flow director side is constrained between the base and the distal end.

21. The back pressure regulator of claim 1, further comprising: a control housing at least partially defining a working fluid chamber; wherein the pressure control member includes: a first member bounding the working fluid chamber; a second member bounding the flow chamber; and an adjuster shaft extending between the first member and the second member; wherein a first pressure in the working fluid chamber biases the pressure control member in a first axial direction and toward a closed state, and a second pressure in the flow chamber biases the pressure control member in a second axial direction opposite the first axial direction and toward an open state.

22. The back pressure regulator of claim 1, wherein, At least 35% of the spray liquid exits the flow chamber from a downstream half of the flow chamber.

23. The back pressure regulator of claim 22, wherein, At least 40% of the spray liquid exits the flow chamber from the downstream half.

24. The back pressure regulator of claim 23, wherein, At least 45% of the spray liquid exits the flow chamber from the downstream half.

25. The back pressure regulator of claim 1, wherein, A ratio of spray liquid flowing out of an upstream half of the flow chamber to spray liquid flowing out of a downstream half of the flow chamber is between 1:1 and 3:

2.

26. A spray system comprising: a liquid reservoir configured to store a supply of spray fluid; a supply line extending between the liquid reservoir and a sprayer; a return line extending between the sprayer and the liquid reservoir; a pump disposed on the supply line; and a back pressure regulator according to any preceding claim disposed on the return line. ​ 27. A method of regulating upstream pressure with a back pressure regulator having a pressure housing and a flow chamber at least partially in the pressure housing, the flow chamber including a chamber inlet and a chamber outlet through the pressure housing and the flow chamber extending circumferentially around the chamber outlet, the method comprising: an upstream ridge dividing an inlet flow of liquid into a first sub-flow and a second sub-flow, the upstream ridge protruding from the pressure housing and into the flow chamber, the upstream ridge elongated along a ridge axis, the ridge axis extending in a flow direction between the chamber inlet and chamber outlet; flowing the first sub-flow through a first side passage that is angled between an upstream end and a downstream end and curved around the chamber outlet; flowing the second sub-flow through a second side passage that is angled between the upstream end and the downstream end and curved around the chamber outlet; reorienting the first sub-flow and the second sub-flow at the downstream end and toward the chamber outlet; flowing the liquid through an annular restriction and to the chamber outlet; and varying a size of the annular restriction based on a volumetric flow rate of the liquid. The step of flowing the liquid through an annular restriction and to the chamber outlet includes:

28. The method of claim 27, wherein, reorienting radial flow into the annular restriction into axial flow out of the annular restriction through a concave curved flow guide disposed on an axis through the chamber outlet. The step of flowing the liquid through the annular restriction and to the chamber outlet includes flowing at least 35% of the liquid from a downstream half of the flow chamber to the annular restriction.

29. The method of claim 27, wherein, The step of flowing the liquid through the annular restriction and to the chamber outlet includes flowing at least 40% of the liquid from the downstream half of the flow chamber to the annular restriction.

30. The method of claim 29, wherein, The step of flowing the liquid through the annular restriction and to the chamber outlet includes flowing at least 45% of the liquid from the downstream half of the flow chamber to the annular restriction.

31. The method of claim 30, wherein, ​

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