Dual-purpose quantitative feeder spring

Abstract

The invention is entitled "Dual-Purpose Doser Spring." An injection assembly for a vehicle exhaust system includes a housing defining a fluid chamber, a doser mounted to the housing and configured to inject fluid into the fluid chamber, and a valve for controlling the flow of the fluid. The valve is movable between an open position and a closed position. A resilient member is configured with a biasing force to bias the valve into the closed position. When the fluid is heated downstream of the valve and exceeds a predetermined pressure level, the biasing force is overcome, causing the fluid to flow back into the fluid chamber.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. patent application No. 17 / 078,688, filed on October 23, 2021, the entire contents of which are incorporated herein by reference. Background Art

[0003] The exhaust system includes a catalyst component to reduce emissions. The exhaust system includes an injection system that injects diesel exhaust fluid (DEF) or a reductant (such as a solution of urea and water) upstream of a selective catalytic reduction (SCR) catalyst for reducing NOx emissions. The injection system includes a dosing device that injects the fluid into the exhaust stream via an injection valve. In one example, the dosing device is configured to heat the DEF to a specified temperature. If the heater fails to shut off as commanded and the valve fails to operate, pressure will increase and an additional pressure relief valve will be used to relieve the pressure. Summary of the Invention

[0004] In one exemplary embodiment, the injection system includes, among other things, a housing defining a fluid chamber, a dosing device mounted to the housing and configured to inject a fluid into the fluid chamber, and a valve for controlling the flow of the fluid. The valve is movable between an open position and a closed position. A resilient member is configured with a biasing force to bias the valve into the closed position. When the fluid is heated downstream of the valve and exceeds a predetermined pressure level, the biasing force is overcome, causing the fluid to flow back into the fluid chamber.

[0005] In another embodiment described above, the heating chamber is fluidly connected to the fluid cavity and the actuator is configured to selectively open the valve so that when the valve is in an open position, fluid flows between the fluid cavity and the heating chamber, and when the valve is in a closed position, fluid is prevented from flowing between the fluid cavity and the heating chamber, and wherein the actuator opens the valve in response to an open command by overcoming a biasing force of a resilient member, and overcomes the biasing force to release the pressure when the pressure of the heating fluid in the heating chamber exceeds a predetermined pressure level.

[0006] In another embodiment of any of the above, the resilient member comprises a coil spring having a first spring end secured within the housing and a second spring end mounted for movement with the armature.

[0007] In another embodiment of any of the above, the actuator includes a coil that is energized in response to an open command to move the armature to compress the coil spring.

[0008] In another embodiment of any of the above, the armature at least partially surrounds the coil spring within the fluid cavity, and wherein the coil surrounds the armature.

[0009] In another embodiment of any of the above, the controller controls the actuator and generates the open command in response to predetermined operating conditions.

[0010] In another embodiment of any of the above, the coil spring comprises the only spring in the housing.

[0011] In another embodiment of any of the above, the heating chamber includes an end wall having an orifice fluidly connecting the fluid cavity and the heating chamber, and includes a valve seat surrounding the orifice, and wherein the valve includes a nozzle tip that fits within the valve seat and seals the orifice when the valve is in the closed position.

[0012] In another embodiment of any of the above, the housing defines a central axis, and wherein the housing includes a flange extending radially outward from an outer surface of the housing relative to the central axis, and wherein one side of the flange provides a mounting surface for the actuator and an opposite side of the flange provides a bottom wall defining a portion of a recess that accommodates an end of the heating chamber.

[0013] In another embodiment of any of the above, a peripheral wall extends axially away from the bottom wall to further define the recess, and wherein the peripheral wall surrounds an end of the heating chamber.

[0014] In a further embodiment of any of the above, the predetermined pressure level is approximately 100 bar.

[0015] In another embodiment of any of the above, the valve comprises the only valve in the housing.

[0016] In another embodiment of any of the above, the fluid includes DEF and the system includes an exhaust component defining an exhaust flow path that receives exhaust gas from the engine, and wherein the DEF is heated to a desired temperature within the heating chamber and injected into the exhaust flow path via the second valve in response to an open command.

[0017] In another exemplary embodiment, a vehicle exhaust system includes, among other things, an exhaust component defining an exhaust flow path that receives exhaust gas from an engine, and an injection assembly configured to inject heated DEF into the exhaust flow path. The injection assembly includes a single resilient member configured to have a biasing force to bias an injection valve to a closed position, wherein when the heated DEF exceeds a predetermined pressure level as commanded, the biasing force is overcome to enable reverse flow. A controller is configured to control the injection of the DEF.

[0018] In another exemplary embodiment, a method includes, inter alia, injecting DEF into an exhaust component defining an exhaust flow path that receives exhaust gas from an engine, the method further comprising the steps of: injecting heated DEF into the exhaust flow path using an injection assembly including a single resilient member; biasing an injection valve to a closed position via a biasing force using the single resilient member; and overcoming the biasing force to enable reverse flow when the heated DEF exceeds a predetermined pressure level.

[0019] These and other features of the present application can be best understood from the following specification and drawings, which are briefly described. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An example of an exhaust system having an injection system according to the present disclosure is schematically shown.

[0021] Figure 2 yes Figure 1 Schematic diagram of the fluid flow within the injection system.

[0022] Figure 3 is used for Figure 1 Cross-sectional side view of a dosing device in an injection system. DETAILED DESCRIPTION

[0023] Figure 1 A vehicle exhaust system 10 is shown, which directs hot exhaust gas generated by an engine 12 through various upstream exhaust components 14 to reduce emissions and control noise, as is known. In one exemplary configuration, upstream exhaust component 14 includes at least one conduit that directs engine exhaust gas to one or more exhaust aftertreatment components. In one example, the exhaust aftertreatment components include a diesel oxidation catalyst (DOC) 16 having an inlet 18 and an outlet 20, and an optional diesel particulate filter (DPF), which, as is known, is used to remove pollutants from the exhaust. Downstream of DOC 16 and the optional DPF is a selective catalytic reduction (SCR) catalyst 22 having an inlet 24 and an outlet 26. Outlet 26 delivers the exhaust gas to downstream exhaust component 28. Optionally, component 22 may include a catalyst configured to perform both a selective catalytic reduction function and a particulate filtering function. Various downstream exhaust components 28 may include one or more of the following: conduits, filters, valves, catalysts, mufflers, etc. These upstream components 14 and downstream components 28 can be installed in a variety of different configurations and combinations depending on the vehicle application and available packaging space.

[0024] In one example, the mixer 30 is located downstream of the outlet 20 of the DOC 16 or DPF and upstream of the inlet 24 of the SCR catalyst 22. For example, the upstream and downstream catalysts may be connected in series or in parallel. The mixer 30 is used to promote mixing of the exhaust gas.

[0025] For example, the injection system 32 is used to inject a reductant, such as diesel exhaust fluid (DEF), into the exhaust gas stream upstream of the SCR catalyst 22 so that the mixer 30 can thoroughly mix the DEF and the exhaust gas. The injection system 32 includes a fluid supply tank 34, a dosing device 36, and a controller 38 that controls the injection of the fluid as is known. In one example, the dosing device 36 injects DEF into the mixer 30, as shown in FIG. Figure 1 In other examples, as schematically indicated at 36 ′, doser 36 may inject DEF into the exhaust system at other locations, such as upstream of mixer 30 .

[0026] Providing ultra-low NOx emissions requires dosing at low temperatures to address NOx removal issues during cold starts and low load cycles. Dosing of DEF at low temperatures causes thermal decomposition and deposit issues because the heat from the exhaust gas is generally insufficient to manage deposits. To address these issues, the injection system 32 heats the DEF before entering the mixer 30, which provides faster atomization and better mixing. A heating element 40 is associated with the doser 36 and is used to preheat the DEF before mixing with the exhaust gas. Any type of heating element 40 suitable for heating DEF can be used. Preheating of the DEF occurs in the doser 36 before the DEF is dosed / injected into the exhaust system 10. The heated DEF can be in the form of a liquid, a gas, or a mixture of the two.

[0027] The control system includes a controller 38 that controls the heating and / or injection of the DEF based on one or more of exhaust temperature, backpressure, time, and wear. Additionally, a plurality of sensors 42 may be used to determine, for example, temperature, flow rate, deposit formation rate, and wear through the system. The sensors 42 transmit data to the controller 38 so that the controller can determine when to generate control signals 44, such as opening and / or closing commands, to the injection system 32.

[0028] The controller 38 may be a dedicated electronic control unit or may be an electronic control unit associated with a vehicle system control unit or a subsystem control unit. The controller 38 may include a processor, memory, and one or more input and / or output (I / O) device interfaces communicatively coupled via a local interface. The controller 38 may be a hardware device for executing software, particularly software stored in memory. The controller 38 may be a custom or commercially available processor, or generally any device for executing software instructions.

[0029] Figure 2 Exhaust components 50, such as conduits, are schematically shown, defining an exhaust flow path F that receives exhaust gas from engine 12. As described above, injection system 32 is configured to inject heated DEF into exhaust flow path F. Injection system 32 includes an inlet chamber or fluid cavity 52 that receives DEF via supply line 54, as indicated at 56. Fluid cavity 52 is in fluid communication with heating chamber 58, which contains DEF, and the heated DEF is heated to a desired temperature via heating element 40 before being injected into exhaust component 50 via valve 61 located within heating chamber 58. Another valve 60 is used to control fluid flow between fluid cavity 52 and heating chamber 58. Valve 60 is configured to serve a dual purpose, operating to control fluid flow during normal operating conditions while also serving as a pressure relief mechanism to allow backflow into supply line 54 and fluid supply tank 34 when the heated DEF exceeds a predetermined pressure level.

[0030] Figure 3 An example of a doser 36 and a valve 60 is shown. A single resilient member 62 is configured with a predetermined biasing force to bias the valve 60 to a closed position. The biasing force is adjusted so that when the heated DEF exceeds a predetermined pressure level, the biasing force can be overcome to enable backflow and pressure venting.

[0031] In one example, the injection assembly includes a housing 64 that defines a fluid cavity 52. ​​The doser 36 is mounted to the housing 64 and is configured to inject DEF into the fluid cavity 52. ​​In one example, the doser 36 includes a body that is received within an aperture 66 formed in the housing 64 and extends to a doser tip 68 that extends outward from the aperture 66 to inject DEF into the fluid cavity 52. ​​The aperture 66 defines a central axis A corresponding to the injection axis. Flow out of the fluid cavity 52 is controlled by a valve 60 that is movable between an open position and a closed position. The resilient member 62 is configured to have a biasing force to bias the valve 60 to the closed position and, as indicated at 70, overcome the biasing force to allow backflow into the fluid cavity 52 when the DEF is heated and exceeds a predetermined pressure level.

[0032] Second housing 72 defines heating chamber 58, which is in fluid communication with fluid cavity 52 via valve 60. Actuator 74 is configured to selectively open valve 60, allowing fluid to flow between fluid cavity 52 and heating chamber 58 when valve 60 is in the open position, and to prevent fluid from flowing between fluid cavity 52 and heating chamber 58 when valve 60 is in the closed position. Actuator 74 opens valve 60 in response to an open command generated by controller 38 based on vehicle operating conditions, as described above. Actuator 74 opens valve 60 by overcoming the biasing force of resilient member 62. When a close command is issued or when actuator 74 is deactivated by controller 38, the biasing force of resilient member 62 returns valve 60 to the closed position. If valve 60 fails and / or if DEF continues to be heated within heating chamber 58, the biasing force of resilient member 62 is overcome when the pressure of the heated DEF in heating chamber 58 exceeds a predetermined pressure level, relieving the pressure and preventing any potential damage to the system.

[0033] In one example, the resilient member 62 comprises a coil spring having a first spring end 76 fixed in the housing 64 and a second spring end 78 mounted to move with the armature 80. In one example, the first spring end 76 engages a portion of the housing surrounding the tip 68 of the dosing device 36. In one example, the armature 80 comprises a tubular body 82 that at least partially surrounds the coil spring. The tubular body 82 is assembled in the fluid chamber 52 and defines an interior space that accommodates the second spring end 78. The tubular body 82 comprises a bottom wall 84 that provides a base for the second spring end 78. The bottom wall 84 comprises an opening 86 that is configured to accommodate at least a portion of the valve 60. An axially extending flange 88 is formed around the opening 86.

[0034] In one example, actuator 74 includes a coil 90 that is energized in response to an open command to move armature 80 to compress the coil spring. Coil 90 surrounds armature 80. When controller 38 activates actuator 74 via an open command, armature 80 is moved upward (see 92) to compress resilient member 62 and open valve 60. When controller 38 deactivates actuator 74, power to coil 90 is cut off, and resilient member 62 returns valve 60 to the closed position via armature 80. During a fault mode, when the pressure of the heated DEF in heating chamber 58 exceeds a predetermined pressure level, the biasing force of resilient member 62 is overcome to displace valve 60. Thus, valve 60 comprises the only valve in housing 64, and coil spring comprises the only spring in housing 64, wherein the spring provides dual functionality as a pressure relief feature for normal operation and a closing feature.

[0035] In one example, the second housing 72 includes an end wall 94 having an orifice 96 that fluidly connects the fluid cavity 52 and the heating chamber 58. A valve seat 98 surrounds the orifice 96. In one example, the valve 60 includes a ball or nozzle tip 100 that fits within the valve seat 98 and covers / seals the orifice 96 when the valve 60 is in the closed position. When the valve 60 is in the closed position, the axially extending flange 88 is pushed against the nozzle tip 100 to force the nozzle tip against the valve seat 108. When the pressure in the heating chamber 58 exceeds a predetermined pressure level, the increased pressure forces the nozzle tip 100 against the axially extending flange 88 to compress the spring and open the valve 60.

[0036] In one example, the housing 64 includes a flange 102 that extends radially outward from an outer surface 104 of the housing 64 relative to the central axis A. One side of the flange 102 provides a mounting surface for the coil 90, and an opposite side of the flange 102 provides a bottom wall 106 that defines a portion of a pocket 108 that receives the end of the second housing 72. A peripheral wall 110 extends axially away from the bottom wall 106 to further define the pocket 108 and surround the end of the second housing 72.

[0037] The present disclosure provides for normal operation of the spring-biased DEF doser 36, wherein a spring applies pressure to the nozzle tip 100 to close the valve 60 and seal the fluid chamber 52, wherein an actuator compresses the spring to open the valve 60 to allow the DEF to be heated to a prescribed temperature within the heating chamber 58 before being injected into the exhaust flow path via valve 61. If the heating element 40 fails to close as commanded and the valves 60 / 61 become inoperative, the same spring used for normal operation also serves to relieve built-up pressure within the heating chamber 58. This eliminates the need for an additional pressure relief valve in the system.

[0038] In one example, the predetermined pressure level in the heating chamber 58 is approximately 6 to 12 bar. The elastic member 62 is adjusted to release 100 bar of DEF liquid and vapor pressure. A small volume of high-pressure DEF (approximately 1 gram at 100 bar) will flow back through the valve 60 and into the DEF supply line 54 or tank 34. When the liquid and gas mixture within the closed heating chamber 58 reaches 300° C., a pressure of approximately 100 bar is generated. The gas is exhausted from the heating chamber 58 and lifts the valve spring, allowing the gas to escape into the inlet fluid chamber 52. In addition to reducing the need for additional parts required for the pressure relief valve and the additional failure modes with the added components, the described configuration improves packaging and reduces costs.

[0039] Although embodiments of this disclosure have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure.For that reason, the following claims should be studied to determine the true scope and content of this disclosure.

Claims

1. An injection assembly for a vehicle exhaust system, the injection assembly comprising: a housing defining a fluid chamber; a dosing device mounted to the housing, the dosing device being configured to inject fluid into the fluid cavity; a valve for controlling the flow of the fluid, the valve being movable between an open position and a closed position; and A resilient member is configured to have a biasing force to bias the valve to the closed position, and wherein when fluid is heated downstream of the valve and exceeds a predetermined pressure level, the biasing force is overcome, allowing fluid to flow back into the fluid chamber.

2. The spray assembly of claim 1 , comprising a heating chamber in fluid communication with the fluid chamber and an actuator, the actuator being configured to selectively open the valve so that fluid flows between the fluid chamber and the heating chamber when the valve is in the open position, and to prevent fluid from flowing between the fluid chamber and the heating chamber when the valve is in the closed position, and wherein the actuator opens the valve in response to an open command by overcoming the biasing force of the resilient member, and when the pressure of the heating fluid in the heating chamber exceeds the predetermined pressure level, the biasing force is overcome to release the pressure.

3. The jetting assembly of claim 2, wherein the resilient member comprises a coil spring having a first spring end fixed within the housing and a second spring end mounted to move with the armature. 4 . The jetting assembly of claim 3 , wherein the actuator includes a coil that is energized in response to the open command to move the armature to compress the coil spring.

5. The jetting assembly of claim 4, wherein the armature at least partially surrounds the coil spring within the fluid chamber, and wherein the coil surrounds the armature.

6. The jetting assembly of claim 3, comprising a controller that controls the actuator and generates the open command in response to predetermined operating conditions.

7. The jetting assembly of claim 3, wherein the coil spring comprises the only spring in the housing.

8. The spray assembly of claim 2 , wherein the heating chamber includes an end wall having an orifice fluidly connecting the fluid cavity and the heating chamber and including a valve seat surrounding the orifice, and wherein the valve includes a nozzle tip that fits within the valve seat and seals the orifice when the valve is in the closed position.

9. The jetting assembly of claim 8 , wherein the housing defines a central axis, and wherein the housing includes a flange extending radially outward from an outer surface of the housing relative to the central axis, and wherein one side of the flange provides a mounting surface for the actuator and an opposite side of the flange provides a bottom wall defining a portion of a recess that receives an end of the heating chamber.

10. The jetting assembly of claim 9, comprising a peripheral wall extending axially away from the bottom wall to further define the pocket, and wherein the peripheral wall surrounds the end of the heating chamber.

11. The jetting assembly of claim 1 , wherein the predetermined pressure level is 100 bar.

12. The spray assembly of claim 1, wherein the valve comprises the only valve in the housing.

13. The injection assembly of claim 2, wherein the fluid comprises DEF and the injection assembly includes an exhaust component defining an exhaust flow path that receives exhaust gas from an engine, and wherein the DEF is heated to a desired temperature within the heating chamber and injected into the exhaust flow path via a second valve in response to the open command.

14. A vehicle exhaust system, comprising: an exhaust component defining an exhaust flow path that receives exhaust gas from the engine; an injection assembly configured to inject heated DEF into the exhaust flow path, wherein the injection assembly includes a single resilient member configured to have a biasing force to bias an injection valve into a closed position, and wherein when the commanded heated DEF exceeds a predetermined pressure level, the biasing force is overcome to enable backflow; and A controller is configured to control injection of the DEF.

15. The vehicle exhaust system of claim 14, wherein the injection assembly comprises: a housing defining a fluid chamber, a dosing device mounted to the housing, the dosing device being configured to inject DEF into the fluid cavity, a heating chamber in fluid communication with the fluid cavity, and an actuator configured to selectively open the injection valve so that fluid flows between the fluid cavity and the heating chamber when the injection valve is in an open position and to prevent fluid from flowing between the fluid cavity and the heating chamber when the injection valve is in a closed position, wherein the actuator opens the injection valve in response to an open command generated by the controller by overcoming the biasing force of the resilient member, and when a pressure of the heated DEF in the heating chamber exceeds a predetermined pressure level, the biasing force is overcome to release the pressure.

16. The vehicle exhaust system of claim 15 , wherein the heating chamber includes an end wall having an orifice fluidically connecting the fluid cavity and the heating chamber and including a valve seat surrounding the orifice, and wherein the injection valve includes a nozzle tip that fits within the valve seat and covers the orifice when the injection valve is in the closed position, and wherein the resilient member includes a coil spring having a first spring end secured within the housing and a second spring end mounted to move with an armature, and wherein the actuator includes a coil that is energized in response to the open command to move the armature to compress the coil spring and release the nozzle tip from sealing engagement with the valve seat.

17. The vehicle exhaust system of claim 14, wherein the predetermined pressure level is 100 bar.

18. A method for injecting DEF into an exhaust component, the exhaust component defining an exhaust flow path that receives exhaust gas from an engine, the method comprising the steps of: injecting heated DEF into the exhaust flow path using an injection assembly including a single elastomeric member; biasing the injection valve to a closed position via a biasing force using the single elastic member; as well as When the heated DEF exceeds a predetermined pressure level, the biasing force is overcome to enable backflow.

19. The method of claim 18, wherein the predetermined pressure level is 100 bar.

20. The method of claim 18, comprising providing to the jetting assembly: a housing defining a fluid chamber, a dosing device mounted to the housing, the dosing device being configured to inject DEF into the fluid cavity, a heating chamber in fluid communication with the fluid cavity, wherein the heating chamber includes an end wall having an orifice, the orifice fluidly connecting the fluid cavity and the heating chamber, and the end wall has a valve seat surrounding the orifice, and wherein the injection valve includes a nozzle tip that fits within the valve seat and seals the orifice when the injection valve is in the closed position, and an actuator configured to selectively open the injection valve such that fluid flows between the fluid cavity and the heating chamber when the injection valve is in the open position, and to prevent fluid from flowing between the fluid cavity and the heating chamber via sealing contact between the nozzle tip and the valve seat when the injection valve is in the closed position, and wherein the actuator opens the injection valve in response to an open command generated by a controller by overcoming the biasing force of the resilient member, and overcomes the biasing force to release the pressure when a pressure of the heated DEF in the heating chamber exceeds a predetermined pressure level.

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