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A sealing device which is used as part of an injector in a reductant delivery unit (RDU), where the RDU is part of a selective catalytic reduction (SCR) system for injecting diesel exhaust fluid (DEF) into an exhaust system, used for controlling exhaust emissions. This invention improves the purging

A sealing device which is used as part of an injector in a reductant delivery unit (RDU), where the RDU is part of a selective catalytic reduction (SCR) system for injecting diesel exhaust fluid (DEF) into an exhaust system, used for controlling exhaust emissions. This invention improves the purging efficiency of the RDU, in addition to improving the sealing performance of the unit by reducing the fluid volume to be evacuated from the injector, and provides an additional sealing barrier to reduce the sealing load of the existing sealing elements. An additional sealing device having a ring seal and a stopper element (also referred to as a “plug”) is pressed into the upper valve body of the injector, which results in a reduced fluid volume that is left behind after a purging event, due to the reduced initial volume at the beginning of the purge.

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1. An apparatus comprising: an injector including: a valve body including a flange portion;a sealing element substantially surrounding the valve body;a cap located over the valve body such that a portion of the cap contacts the sealing element, the cap comprising a large diameter portion substantial

1. An apparatus comprising: an injector including: a valve body including a flange portion;a sealing element substantially surrounding the valve body;a cap located over the valve body such that a portion of the cap contacts the sealing element, the cap comprising a large diameter portion substantially surrounding the sealing element such that an inner surface of the large diameter portion is in contact with the sealing element; anda sealing device disposed between the valve body and the cap for substantially providing a sealing function between the cap and the valve body, the sealing device comprising: a stopper element received into a cavity formed as part of the valve body, the stopper element connecting the sealing device to the valve body; anda ring seal connected to the stopper element;wherein the ring seal is in contact with the cap and an upper surface of the flange portion of the valve body, providing the sealing function between the cap and the valve body, an outer radial surface of the ring seal being spaced, in a radial direction, a distance apart from an inner surface of the large diameter portion of the cap, the distance between the outer radial surface of the ring seal and the inner surface of the large diameter portion of the cap in the radial direction is less than a distance between a distal end of the flange portion of the valve body and the inner surface of the large diameter portion of the cap in the radial direction,the cap further comprises a circumferential flange integrally formed with the large diameter portion, a portion of the sealing device in contact with the circumferential flange when the cap is located over the valve body;the apparatus further comprises a small diameter portion integrally formed with the circumferential flange of the cap, the small diameter portion being part of the cap, anda separate inlet connected to the small diameter portion of the cap, such that fluid flows through the inlet and through the small diameter portion; andthe inlet further comprises an aperture formed as part of the inlet substantially aligned with an aperture formed as part of the sealing device, such that fluid passes through the inlet, the stopper element, and the ring seal to pass through the valve body, anda first portion having a first outer diameter and a first inner diameter, and a second portion having a second outer diameter smaller than the first outer diameter and a second inner diameter, the second portion received into and surrounded by the small diameter portion of the cap and the first portion being disposed externally to the cap. 2. The apparatus of claim 1, the stopper element further comprising: a first rib formed as part of the stopper element; anda second rib formed as part of the stopper element in proximity to the first rib;wherein the first rib and the second rib are substantially in contact with an inner surface of the valve body, connecting the stopper element to the valve body, and the valve body includes a radially extending notch, the first and second ribs are disposed between the flange portion of the valve body and the radially extending notch. 3. The apparatus of claim 1, the ring seal further comprising: a circumferential portion having a lower surface in contact with the flange portion of the valve body; anda plurality of ribs formed as part of the circumferential portion, each of the plurality of ribs in contact with an inner surface of the cap, the plurality of ribs comprising annular ribs concentric with each other;wherein each of the plurality of ribs provides the sealing function between the cap and the valve body. 4. The apparatus of claim 3, wherein the lower surface of the circumferential portion is in contact with the flange portion. 5. The apparatus of claim 1, further comprising: a groove formed as part of the stopper element;a ridge formed as part of the stopper element in proximity to the groove formed as part of the stopper element;a lip portion formed as part of the ring seal; anda groove formed as part of the ring seal in proximity to the lip portion formed as part of the ring seal;wherein the lip portion is disposed in the groove formed as part of the stopper element and the ridge is disposed in the groove formed as part of the ring seal when the stopper element is connected to the ring seal. 6. The apparatus of claim 1, wherein the sealing element is an O-ring. 7. The apparatus of claim 1, the ring seal forming a ring seal aperture through the ring seal and the stopper element forming a stopper aperture through the stopper element, the ring seal aperture and the stopper aperture combining to form the aperture formed as part of the sealing device, the ring seal aperture having a larger diameter than the stopper aperture. 8. An injector having a sealing device, comprising: an upper valve body having a flange portion;an O-ring substantially surrounding an outer surface of the upper valve body;a cap located over the upper valve body such that a portion of the cap contacts the O-ring providing a sealing function between the cap and the upper valve body;a stopper element partially disposed in a cavity formed as part of the upper valve body; anda ring seal connected to the stopper element;wherein the ring seal is at least partially positioned between the flange portion and the cap, providing a sealing function between the flange portion and the cap, the cap comprising a large diameter portion substantially surrounding the O-ring such that an inner surface of the large diameter portion is in contact with the O-ring, the ring seal including an outer radial surface being spaced a distance apart from the inner surface of the large diameter portion of the cap, andthe ring seal comprises: a circumferential portion having a lower surface in contact with the flange portion of the upper valve body; anda plurality of ribs formed as part of the circumferential portion, each of the plurality of ribs in contact with an inner surface of the cap, the plurality of ribs comprising annular ribs concentric with each other;wherein each of the plurality of ribs provides the sealing function between the cap and the upper valve body,the cap comprises a small diameter portion and a circumferential flange integrally formed with the small diameter portion, a portion of the ring seal in contact with the circumferential flange when the cap is located over the valve body, the large diameter portion being integrally formed with the circumferential flange; andthe injector further comprises: a separate inlet connected to the small diameter portion;an aperture formed as part of the inlet substantially aligned with an aperture formed as part of the stopper element and an aperture formed as part of the ring seal, such that fluid is allowed to pass through the inlet, the stopper element, and the ring seal to pass through the valve body; anda first inlet portion formed as part of the inlet and having a first outer diameter and a first inner diameter, and a second portion formed as part of the inlet and having a second outer diameter smaller than the first outer diameter and a second inner diameter, the second inlet portion received into and surrounded by the small diameter portion of the cap and the first portion being disposed externally to the cap. 9. The injector having a sealing device of claim 8, the stopper element further comprising: a first rib disposed in the cavity and in contact with an inner surface of the upper valve body; anda second rib disposed in the cavity and in contact with the inner surface of the upper valve body;wherein a force is applied to the first rib and the second rib by the inner surface of the upper valve body, securing the stopper element to the upper valve body, the upper valve body includes a radially extending notch, and the first and second ribs are disposed between the flange portion of the valve body and the radially extending notch. 10. The injector having a sealing device of claim 8, further comprising: a groove formed as part of the stopper element;a ridge formed as part of the stopper element in proximity to the groove formed as part of the stopper element;a lip portion formed as part of the ring seal; anda groove formed as part of the ring seal in proximity to the lip portion formed as part of the ring seal;wherein the lip portion is disposed in the groove formed as part of the stopper element and the ridge is disposed in the groove formed as part of the ring seal when the stopper element is connected to the ring seal. 11. The injector having a sealing device of claim 8, the aperture formed as part of the ring seal having a larger diameter than the aperture formed as part of the stopper element. 12. The injector of claim 8, where the distance between the outer radial surface of the ring seal and the inner surface of the large diameter portion of the cap, in a radial direction of the ring seal, is less than a distance between a distal end of the flange portion of the valve body and the inner surface of the large diameter portion of the cap in the radial direction. 13. An injector having a sealing device, comprising; an upper valve body having a flange portion;an O-ring surrounding and in contact with an outer surface of the upper valve body;a cap having a large diameter portion, a small diameter portion and a circumferential flange integrally formed together, the large diameter portion of the cap substantially surrounds the O-ring such that an inner surface of the large diameter portion of the cap contacts the O-ring, at least partially compressing the O-ring, providing a sealing function between the O-ring and the large diameter portion of the cap and between the O-ring and the outer surface of the upper valve body;a stopper element having an aperture;a first rib formed as part of the stopper element;a second rib formed as part of the stopper element in proximity to the first rib, the first and second ribs contacting an inner surface of the upper valve body;a ring seal;a circumferential portion formed as part of the ring seal, the circumferential portion having a lower surface in contact with the flange portion of the upper valve body;a plurality of ribs formed as part of the circumferential portion of the ring seal, each of the plurality of ribs in contact with an inner surface of the circumferential flange of the cap, the plurality of ribs formed as part of the circumferential portion of the ring seal comprising concentric annular ribs;an aperture formed as part of the ring seal;a separate inlet piece;an aperture formed as part of the inlet piece substantially aligned with the aperture of the stopper element and the aperture of the ring seal, such that fluid passes through the inlet piece, the stopper element, and the ring seal to pass through the valve body; anda first inlet portion formed as part of the inlet piece having a first outer diameter and a first inner diameter, and a second inlet portion formed as part of the inlet piece having a second outer diameter smaller than the first outer diameter and a second inner diameter, the second inlet portion received into and surrounded by the small diameter portion of the cap and the first inlet portion disposed external to the cap;wherein each of the plurality of ribs in contact with the inner surface of the circumferential flange and the lower surface of the circumferential portion of the ring seal in contact with the flange portion provides a sealing function. 14. The injector having a sealing device of claim 13, further comprising: a groove formed as part of the stopper element;a ridge formed as part of the stopper element in proximity to the groove formed as part of the stopper element;a lip portion formed as part of the ring seal; anda groove formed as part of the ring seal in proximity to the lip portion formed as part of the ring seal;wherein the lip portion is disposed in the groove formed as part of the stopper element and the ridge is disposed in the groove formed as part of the ring seal when the stopper element is connected to the ring seal. 15. The injector having a sealing device of claim 13, the aperture formed as part of the ring seal having a larger diameter than the aperture of the stopper element.