Apparatus and method for coating a substrate with a washcoat

Abstract

An apparatus and method for coating a substrate with a washcoat, in which the substrate (10) is engaged with a head set (6) of a substrate coating apparatus (1) beneath a washcoat showerhead (5). The washcoat is dispensed from the washcoat showerhead (5) under the control of a valve assembly (4) onto an upper surface (12) of the substrate, and is then drawn through the substrate with the use of a vacuum generator (7). The valve assembly (4) includes an outlet valve movable between a closed state and an open state. The valve assembly (4) creates a pressure drop inside the washcoat showerhead (5) when the outlet valve moves from its open state to its closed state. This prevents the washcoat from dripping from the washcoat showerhead (5) after the valve assembly is closed.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates to an apparatus and method for coating a substrate with a washcoat, and in particular, it relates to coating a substrate used for exhaust gas purification. [Background technology]

[0002] Substrates for exhaust gas purification typically include a monolith substrate provided with passages for the throughflow of exhaust gas. The substrate can be provided with a coating, which can be a catalytic coating. The coating can be applied to the substrate as a washcoat that passes through the passages in the substrate. Various methods are known for applying a coating to a substrate. One such method includes applying a washcoat to a first side (e.g., top side) of the substrate and exposing an opposite second side (e.g., bottom side) of the substrate to at least a partial vacuum to achieve movement of the washcoat through the passages. After coating, the substrate can be dried and calcined.

[0003] The substrate can be configured as a flow-through substrate, with each passage open on both the first and second sides of the substrate, and the passages extending through the entire length of the substrate. As a result, exhaust gas entering a passage through the first side of the substrate continues through the substrate in the same manner until it exits the second side of the substrate. Alternatively, the substrate can be configured as a filter substrate, with some passages plugged on the first side of the substrate and other passages plugged on the second side of the substrate. In such a configuration, exhaust gas entering a first passage through the first side of the substrate flows along the first passage partway along the substrate before passing through the filtering wall of the substrate and entering a second passage. The exhaust gas then continues along the second passage and exits the second side of the substrate. This arrangement has become known in the art as a wall-flow filter.

[0004] The coated flow-through substrate may comprise a three way catalyst (TWC), a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), a lean NOx trap catalyst (LNT), an ammonia slip catalyst (ASC), a combined selective catalytic reduction catalyst and ammonia slip catalyst (SCR / ASC), or a passive NOx adsorber (PNA).

[0005] The coated filter substrate may be, for example, a catalyzed soot filter (CSF) with an oxidation catalyst, a selective catalytic reduction filter (SCRF) with a selective catalytic reduction catalyst (SCR), a lean NOx trap filter (LNTF) with a NOx adsorber composition, a gasoline particulate filter (GPF) with a three-way catalyst composition, or a filter substrate with a selective catalytic reduction (SCR) catalyst and an ammonia slip catalyst (ASC).

[0006] The substrate may be made of or comprised of a ceramic or metallic material, for example, aluminum titanate, cordierite (SiO-AlO-MgO), silicon carbide (SiC), Fe-Cr-Al alloy, Ni-Cr-Al alloy, or stainless steel alloy.

[0007] The substrate generally has a substrate body with a uniform cross-sectional shape along its longitudinal length. Typically, the substrate body may have a circular or nearly circular cross-section, although other cross-sectional shapes, such as square and rectangular, are possible. The upper surface of the substrate body may be defined as the surface positioned uppermost during coating, and similarly, the lower surface of the substrate body may be defined as the surface positioned lowermost during coating. Generally, the upper and lower surfaces are planar and perpendicular to the longitudinal axis of the substrate body.

[0008] When coating a substrate, it may typically be desirable to achieve a substantially "flat" washcoat profile, i.e., a "tip" or "leading edge" of the washcoat that is substantially flat or perpendicular to the longitudinal axis of the passage (marking a boundary interface between coated and uncoated portions of the substrate).

[0009] An uneven washcoat profile can have a detrimental effect on the operating efficiency of the substrate. For example, an uneven profile can lead to portions of the substrate not being coated (reducing the catalytic efficiency of the substrate) or portions of the substrate being unintentionally coated more than once—multiple doses of washcoat being applied—which can detrimentally increase backpressure on the substrate. In some situations, the washcoat can be pulled completely through the substrate body and emerge from the lower surface.

[0010] To achieve a uniform washcoat profile, it may be desirable to achieve a uniform depth of washcoat across the upper surface of the substrate before the substrate is drawn through the substrate. Factors that can affect the depth of the washcoat across the upper surface include the uniformity of the deposition of the washcoat on the upper surface and the rate at which the washcoat spreads while it is on the upper surface.

[0011] Another factor that can affect performance is dripping or leakage of washcoat from the washcoat showerhead. Showerheads are described, for example, in International Publication No. 2015145122. Such leakage or dripping (after a desired volume of washcoat has been dispensed from the washcoat showerhead) can lead to excess washcoat on the upper surface. This can result in reduced operational economy due to wasted washcoat. It can also lead to the washcoat being pulled sufficiently through a portion of the substrate body to emerge from the lower surface. This can lead to potential blockage of passage openings on the lower surface of the substrate. Such leakage and dripping can also lead to deposits remaining on the upper surface, which can block passage openings on the upper surface of the substrate and result in visual degradation of the substrate that is deemed undesirable by customers. Summary of the Invention

[0012] In a first aspect, the present disclosure provides a method of coating a substrate with a washcoat, the method comprising: engaging the substrate with a head set of the substrate coating apparatus such that the upper surface of the substrate is positioned under a washcoat showerhead of the substrate coating apparatus; transporting washcoat from a washcoat source toward a washcoat showerhead; controlling the flow of washcoat from a supply to an interior of the washcoat showerhead using a valve assembly; Discharging a washcoat from a washcoat showerhead toward an upper surface of a substrate; and drawing the washcoat through the substrate by applying a suction force to a lower surface of the substrate; The valve assembly includes an outlet valve movable between a closed state and an open state to control the flow of washcoat into the interior of the washcoat showerhead, and the valve assembly creates a pressure drop within the washcoat showerhead when the outlet valve moves from its open state to its closed state.

[0013] Advantageously, the method can mitigate dripping and / or leakage of the washcoat from the washcoat showerhead after the valve assembly is closed. The pressure drop inside the washcoat showerhead can act to create a suction force that reduces or prevents dripping or leakage of the washcoat.

[0014] The outlet valve may include a valve stem that reciprocates against a valve seat.

[0015] The valve stem or a valve seal provided on the valve stem may sealingly engage the valve seat when the outlet valve is in a closed state. Optionally, the valve stem or a valve seal provided on the valve stem may sealingly engage a downstream face of the valve seat when the outlet valve is in a closed state.

[0016] The valve stem or valve seal may be pulled into sealing engagement with the valve seat in the outlet valve closed state.

[0017] The valve stem may extend through the valve seat in both the open and closed positions.

[0018] The valve assembly may create a pressure drop within a valve chamber of the valve assembly when moving from an open state to a closed state.

[0019] The valve stem can act as a piston within the valve chamber and can create a pressure drop within the valve chamber when moving from an open to a closed state.

[0020] The valve stem may extend toward the outlet when the outlet valve moves to its open state and retract away from the outlet when the outlet valve moves to its closed state.

[0021] The volume of the valve chamber that can accommodate the washcoat may be greater in the outlet valve closed state than in the outlet valve open state.

[0022] The valve stem may be moved by a valve stem actuator, which may be a pneumatic, hydraulic, or electromechanical actuator.

[0023] In a washcoat showerhead, the washcoat may enter the center of the upper interior, then flow toward the outer edge of the interior, then be directed downwards to enter the lower interior, where it may be directed to flow inward toward the center of the washcoat showerhead.

[0024] The washcoat may be ejected from the lower interior through an array of apertures disposed in the lower layer of the washcoat showerhead. A pressure drop within the washcoat showerhead may act to create a suction force at the array of apertures that reduces or prevents dripping or leakage of the washcoat.

[0025] In a second aspect, the present disclosure provides a substrate coating apparatus, the substrate coating apparatus comprising: a source of washcoat; a washcoat showerhead for dispensing the washcoat toward an upper surface of the substrate; a head set for engaging the substrate so as to position an upper surface of the substrate under the washcoat showerhead; a vacuum generator for sucking the washcoat discharged from the washcoat showerhead through the substrate; The substrate coating apparatus further comprises a valve assembly for controlling the flow of the washcoat into the washcoat showerhead, the valve assembly comprising: an inlet for receiving washcoat provided from a washcoat supply; an outlet for delivering the washcoat to the shower head; an outlet valve movable between a closed state and an open state to control the flow of washcoat out of the outlet; The valve assembly is configured to create a pressure drop within the washcoat showerhead when the outlet valve moves from its open state to its closed state.

[0026] Advantageously, the substrate coating apparatus can mitigate dripping and / or leakage of the washcoat from the washcoat showerhead after the valve assembly is closed. A pressure drop within the washcoat showerhead can act to create a suction force that reduces or prevents dripping or leakage of the washcoat.

[0027] The outlet valve may include a valve stem configured to reciprocate against a valve seat.

[0028] The valve stem or a valve seal provided on the valve stem may be configured to sealingly engage the valve seat when the outlet valve is in a closed state. The valve stem or a valve seal provided on the valve stem may be configured to sealingly engage a downstream face of the valve seat when the outlet valve is in a closed state.

[0029] The valve stem or valve seal may be configured to be pulled into sealing engagement with the valve seat by the valve stem actuator in the closed state of the outlet valve.

[0030] The valve stem may extend through the valve seat in both the open and closed positions.

[0031] The valve assembly may further comprise a valve chamber.

[0032] The valve assembly may be configured to create a pressure drop within the valve chamber when moving from an open state to a closed state.

[0033] The valve stem may be configured to act as a piston within the valve chamber, creating a pressure drop within the valve chamber when moving from an open to a closed state.

[0034] The valve chamber of the valve assembly may be fluid-tight sealed to the interior of the washcoat showerhead.

[0035] The valve stem may extend toward the outlet when the outlet valve moves to its open state and retract away from the outlet when the outlet valve moves to its closed state.

[0036] The valve assembly may be configured so that the volume of the valve chamber that can accommodate the washcoat is greater in the outlet valve closed state than in the outlet valve open state.

[0037] The valve stem may include an enlarged valve stem head and may include a valve stem seal disposed adjacent a proximal face of the enlarged valve stem head.

[0038] An enlarged valve stem head may be positioned downstream of the valve seat in both the open and closed states.

[0039] The valve stem seal may comprise an O-ring, optionally an EPDM O-ring.

[0040] The substrate coating apparatus may further comprise a valve stem actuator, which may be a pneumatic, hydraulic, or electromechanical actuator.

[0041] The washcoat showerhead may include a housing including an upper layer having a fluid connection to the outlet of the valve assembly and a lower layer including an array of apertures for ejecting the washcoat toward the upper surface of the substrate. A pressure drop within the washcoat showerhead may act to create a suction force at the array of apertures that reduces or prevents dripping or leakage of the washcoat.

[0042] The array of apertures may comprise a plurality of equally spaced apertures.

[0043] The inner diameter of the or each aperture may be 1.5 to 2.5 mm, optionally about 2 mm, optionally 2 mm. Sizing the inner diameter of each aperture may be particularly beneficial for creating suction forces in the array of apertures that reduce or prevent dripping or leakage of the washcoat.

[0044] The or each aperture may be defined by a tubular insert.

[0045] The tubular insert of the or each aperture may extend below the lower surface of the underlying layer by at least 1 mm, more preferably at least 2 mm, most preferably at least 5 mm, or about 5 mm, or 5 mm.

[0046] The washcoat showerhead may further include a baffle layer that may be configured to direct washcoat flowing into the center of the top of the interior toward the outer edge of the interior.

[0047] The baffle layer may be configured to transport the washcoat to a lower portion of the interior at or near the outer edge of the interior so that the washcoat may be directed to continue flowing inward across the upper surface of the lower layer toward the center of the lower layer.

[0048] The top layer and the baffle layer may be separated by a first gap, optionally the first gap may be between 3.0 and 5.0 mm, optionally about 4.0 mm, optionally 4.0 mm.

[0049] The baffle layer and the underlayer may be separated by a second gap, optionally the second gap may be between 3.0 and 5.0 mm, optionally about 4.0 mm, optionally 4.0 mm.

[0050] The upper layer, the baffle layer, and the lower layer may be sealed together, optionally with at least a first O-ring seal between the upper layer and the baffle layer, and a second O-ring seal between the baffle layer and the lower layer.

[0051] The outlet valve may comprise a reverse poppet valve.

[0052] In a third aspect, the present disclosure provides a valve assembly for a substrate coating apparatus, the valve assembly comprising: A valve chamber; an entrance for receiving wash coats; an outlet for delivering the washcoat to the shower head; an outlet valve movable between a closed state and an open state to control the flow of washcoat out of the outlet; The valve assembly is configured to create a pressure drop within the valve chamber when the outlet valve moves from its open state to its closed state.

[0053] Advantageously, the valve assembly (when assembled with a washcoat showerhead) can mitigate dripping and / or leakage of washcoat from the washcoat showerhead after the valve assembly is closed. The pressure drop within the valve chamber can act to create a suction force that reduces or prevents dripping or leakage of washcoat.

[0054] The outlet valve may include a valve stem configured to reciprocate against a valve seat.

[0055] The valve stem may be configured to act as a piston within the valve chamber, creating a pressure drop within the valve chamber when moving from an open to a closed state.

[0056] The valve stem or a valve seal provided on the valve stem may be configured to sealingly engage the valve seat when the outlet valve is in a closed state. The valve stem or a valve seal provided on the valve stem may be configured to sealingly engage a downstream face of the valve seat when the outlet valve is in a closed state.

[0057] The valve stem or valve seal may be configured to be pulled into sealing engagement with the valve seat by the valve stem actuator in the closed state of the outlet valve.

[0058] The valve stem may extend through the valve seat in both the open and closed positions.

[0059] The valve stem may extend toward the outlet when the outlet valve moves to its open state and retract away from the outlet when the outlet valve moves to its closed state.

[0060] The valve stem may include an enlarged valve stem head and may include a valve stem seal disposed adjacent a proximal face of the enlarged valve stem head.

[0061] An enlarged valve stem head may be positioned downstream of the valve seat in both the open and closed states.

[0062] The valve stem seal may comprise an O-ring, optionally an EPDM O-ring.

[0063] The valve assembly may further comprise a valve stem actuator, which may optionally be a pneumatic, hydraulic or electromechanical actuator.

[0064] The outlet valve may comprise a reverse poppet valve.

[0065] In any of the above aspects, the substrate may be selected from a flow-through substrate (eg, a monolithic flow-through substrate) or a filter substrate (eg, a wall-flow filter substrate).

[0066] In any of the above embodiments, the washcoat may comprise a catalytic coating selected from a three-way catalyst (TWC), a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), a lean NOx trap catalyst (LNT), an ammonia slip catalyst (ASC), a combined selective catalytic reduction catalyst and ammonia slip catalyst (SCR / ASC), or a passive NOx adsorber (PNA).

[0067] In any of the above embodiments, the washcoat may have a viscosity of 3 to 9000 cP, optionally 3 to 54 cP, optionally 32 to 576 cP, optionally 23 to 422 cP, optionally 250 to 4500 cP, optionally 500 to 9000 cP.

[0068] All references to viscosity herein refer to the viscosity of a fluid as measured using a Brookfield rotational viscometer fitted with a Small Sample Adaptor and a link hanging spindle, with the sample temperature controlled at 25° C. Such a viscometer is available from Brookfield Engineering Laboratories, Inc., Middleboro, MA, USA.

[0069] All measurements were taken in 14 seconds. -1As is common knowledge to those skilled in the art, the spindle, rotation speed, and viscometer model were selected depending on the viscosity of the fluid to ensure that the percent viscometer torque has a minimum measurement value greater than 10% and a maximum measurement value less than 100%, but if this is not possible, the percent viscometer torque may have a minimum measurement value greater than 0% and a maximum measurement value less than 100%. For the viscosity measurements herein, the following spindles were used: The viscosity range of 3-100 cP was measured in an LV viscometer using spindle SC4-18 at 10.6 rpm. The viscosity range of 100-500 cP was measured in an LV viscometer using spindle SC4-28 at 50 rpm. The viscosity range of 500-9000 cP was measured in an RV viscometer using spindle SC4-28 at 50 rpm. [Brief explanation of the drawings]

[0070] Aspects and embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of a substrate coating apparatus. [Figure 2] 1 is a cross-sectional view of a first embodiment of a valve assembly for a substrate coating apparatus. [Figure 3] FIG. 3 is a view of the valve assembly of FIG. 2 in an exploded state with certain parts omitted for clarity. [Figure 4] FIG. 1 is an exploded cross-sectional view of a washcoat showerhead for a substrate coating apparatus. [Figure 5] FIG. 5 is a plan view from below of the washcoat showerhead of FIG. 4. [Figure 6] FIG. 5 is a plan view from below of the baffle layer of the washcoat showerhead of FIG. 4. [Figure 7] FIG. 2 is a cross-sectional view of a second embodiment of a valve assembly for a substrate coating apparatus. [Figure 8] FIG. 10 is a cross-sectional view of a comparative valve. [Figure 9] FIG. 1 is a cross-sectional view of a comparative washcoat showerhead. DETAILED DESCRIPTION OF THE INVENTION

[0071] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a catalyst" includes a mixture of two or more catalysts, and the like.

[0072] As used herein, the term "about" is inclusive of the specific value. For example, "about 45%" means about 45%, and also includes 45% within its meaning.

[0073] Those skilled in the art will recognize that one or more features of one aspect or embodiment of the present disclosure may be combined with one or more features of any other aspect or embodiment of the present disclosure, unless the immediate context teaches otherwise.

[0074] 1 shows a schematic diagram of a non-limiting example of a substrate coating apparatus 1 that can be used to coat a substrate 10 with a washcoat. The substrate coating apparatus 1 includes a washcoat source 2, a valve assembly 4, a washcoat showerhead 5, a headset 6, and a vacuum generator 7.

[0075] The substrate 10 may be of a type including a substrate body 11 having a uniform cross-sectional shape along its longitudinal length, for example. Typically, the substrate body 11 may have a circular or nearly circular cross-section. The substrate body 11 may be positioned within the substrate coating apparatus 1 so that an upper surface 12 of the substrate body 11 is at the top and a lower surface 13 of the substrate body 11 is at the bottom. The upper surface 12 and the lower surface 13 may be planar and perpendicular to the longitudinal axis of the substrate body 11.

[0076] In use, the washcoat source 2 can supply the washcoat via the conduit 3 to the valve assembly 4. The source 2 can take a variety of forms. In one non-limiting example, the source 2 can include a hopper reservoir of washcoat and a dispensing mechanism for supplying a controlled volume of the washcoat from the hopper reservoir to the valve assembly 4. The dispensing mechanism can include, for example, a piston axially movable within a bore to provide a driving force for moving the washcoat into and / or along the conduit 3 toward the valve assembly 4. The source 2 can also include an on / off valve (e.g., a ball valve or a diaphragm valve) disposed between the hopper reservoir (or equivalent) and the valve assembly 4.

[0077] The substrate 10 may be placed and positioned between the headset 6 and a pallet insert 9 or other substrate tool. The pallet insert 9 or other substrate tool may be attached to the rotary table 8. The pallet insert 9 or other substrate tool may be vertically movable relative to the rotary table 8 and the headset 6. The rotary table 8 may allow the pallet insert 9 or other substrate tool to move laterally relative to the headset 6.

[0078] The washcoat showerhead 5 is configured to dispense a washcoat toward the upper surface 12 of the substrate 10. The washcoat showerhead 5 may be positioned above the headset 6 and may be aligned with the headset 6 and the substrate 10 such that the central longitudinal axis of the washcoat showerhead 5 coincides with the central longitudinal axes of both the headset 6 and the substrate body 11.

[0079] The headset 6 is configured to engage the substrate 10 so as to position the upper surface 12 of the substrate 10 below the washcoat showerhead 5. The headset 6 may include a headset seal 15 that may engage an upper edge circumscribing the upper surface 12 of the substrate body 11. The headset seal 15 may include an annular ring that extends around the entire circumference of the headset 6.

[0080] The vacuum generator 7 is configured to draw the washcoat dispensed from the washcoat showerhead 5 through the substrate 10. The vacuum generator 7 may comprise a vacuum cone that may be positioned below the substrate 10. The vacuum generator 7 may be configured to apply a suction force to the lower surface 13 of the substrate 10. The vacuum generator 7 may comprise a device or combination of devices that function to generate reduced pressure. Non-limiting examples of suitable devices include vacuum generators that operate on the Venturi principle, vacuum pumps, e.g., rotary vane and liquid ring vacuum pumps, and vortex blowers.

[0081] The valve assembly 4 is configured to control the flow of washcoat into the washcoat showerhead 5 .

[0082] A first embodiment of a valve assembly 4 according to the present disclosure is shown in Figures 2 and 3. The valve assembly 4 may include a valve body housing 20, a valve stem actuator 21, a valve stem 23, and a valve seat 24.

[0083] The valve assembly 4 includes an inlet 35 for receiving washcoat from the washcoat source 2, an outlet 36 for delivering washcoat to the washcoat showerhead 5, and a valve chamber 37.

[0084] The valve body housing 20 may, for example, have a T-shaped configuration with a longitudinal portion 30 and a transverse portion 33. It will be understood that such a configuration is merely one contemplated example and that other configurations for the valve body housing 20 may be used.

[0085] The longitudinal portion can extend between an upper end 31 adapted to connect directly or indirectly to the valve stem actuator 21 and a lower end 32 adapted to connect directly or indirectly to the washcoat showerhead 5.

[0086] The upper end 31 may be directly coupled to the valve stem actuator 21. Alternatively, the coupling may be an indirect coupling to an actuator coupling 22, where the coupling is sandwiched between the upper end 31 and the valve stem actuator 21, as shown in Figure 2. The valve stem actuator 21 may be coupled to the valve body housing 20 by fasteners, such as bolts, that pass through the actuator coupling 22.

[0087] The lower end 32 may be directly coupled to the washcoat showerhead 5 and thus may define the outlet 36. Alternatively, as shown in FIG. 2, the coupling may be indirect with the valve seat 24 and outlet coupling 25, where the coupling is sandwiched between the lower end 32 and the washcoat showerhead 5. In this example, the outlet coupling 25 defines the outlet 36. The outlet coupling 25 may be coupled to the valve body housing 20 by fasteners, such as bolts, that pass through the outlet coupling 25. To ensure a fluid-tight coupling of the washcoat showerhead 5 to the valve assembly 4, a first gasket seal 71, shown in FIG. 3, may be sandwiched between the valve body housing 20 and the valve seat 24, and a second gasket seal 72, also shown in FIG. 3, may be sandwiched between the valve seat 24 and the outlet coupling 25.

[0088] The outlet connection 25 may include a flange 80 that may be sized and shaped to connect to the flange 105 of the washcoat showerhead 5 shown in FIG.

[0089] The transverse portion 33 may extend between the longitudinal portion 30 and the inlet 35. A fitting 34 may be provided at the inlet end of the transverse portion 33 for directly or indirectly connecting the valve body housing 20, and thus the valve assembly 4, to the conduit 3. The fitting 34 may comprise a flange, a threaded joint, or other means for fluid-tightly connecting the conduit 3 to the valve assembly 4.

[0090] The longitudinal portion 30 and the lateral portion 33 may each have hollow bores that are interconnected where they intersect, allowing the washcoat to flow freely from the lateral portion 33 into the longitudinal portion 30 during use.

[0091] The valve stem actuator 21 may include an actuator body 40 and an actuator stem 41. The actuator stem 41 may be configured to engage an upper end 62 of the valve stem 23. The actuator stem 41 and the upper end 62 may be fixedly or removably attached together. The actuator stem 41 and the upper end 62 may be molded to each other to form an interlocking configuration. The interlocking configuration may include interlocking protrusions and undercuts.

[0092] The valve stem actuator 21 may be a pneumatic, hydraulic, or electromechanical actuator. The actuator body 40 may include inlet and / or outlet connections for coupling to a pneumatic, hydraulic, or electric power source.

[0093] The valve stem 23 may comprise an elongated member, which may comprise a single component or multiple components assembled together.

[0094] The valve stem 23 may include an upper portion 60 and a lower portion 61. The upper portion 60 may be a cylindrical portion of a first diameter. An upper end 62 may be provided at the upper end of the upper portion 60. The lower portion 61 may be a cylindrical portion of a second diameter. The first diameter may be greater than the second diameter.

[0095] The valve stem 23 may include an enlarged valve stem head 63. The enlarged valve stem head 63 may be provided at the lower end of the enlarged valve stem head 63, optionally at the lower end of the lower portion 61.

[0096] The valve stem 23 may include a valve stem seal 64. The valve stem seal may be disposed adjacent a proximal face of the enlarged valve stem head 63. The valve stem seal 64 may include an O-ring, for example an EPDM O-ring.

[0097] The valve seat 24 may define a sealing surface 70 that is engaged by the valve stem 23 and / or the valve stem seal 64. The sealing surface 70 may be on a downstream surface of the valve seat 24 that faces the outlet 36. The valve seat 24 may define an aperture 73. The valve seat 24 may be annular with the aperture 73 disposed as a central passage surrounded by the sealing surface 70.

[0098] The valve seat 24 may be integrally formed with the valve body housing 20. Alternatively, as shown in FIG. 2, the valve seat 24 may be formed as a separate component coupled to the valve body housing 20. In the illustrated example, the bolts connecting the outlet connection 25 to the valve body housing 20 also pass through the valve seat 24. As mentioned above, to ensure a fluid-tight connection of the washcoat showerhead 5 to the valve assembly 4, a first gasket seal 71 may be sandwiched between the valve body housing 20 and the valve seat 24, and a second gasket seal 72 may be sandwiched between the valve seat 24 and the outlet connection 25.

[0099] The enlarged valve stem head 63 may be located downstream of the valve seat 24. That is, the valve stem 23 may protrude through the aperture 73. The valve stem 23 may extend through the valve seat 24 in both the open and closed positions of the valve assembly 4.

[0100] Valve stem 23 may be mounted for reciprocal movement relative to valve seat 24. As shown in FIG. 2 , an upper portion 60 of valve stem 23 may protrude through upper end 31 of longitudinal portion 30 and actuator coupling portion 22 to engage actuator stem 41 of valve stem actuator 21.

[0101] A rod seal or bushing 50 may be provided between the actuator coupling 22 and the valve stem 23. The rod seal or bushing 50 may function to provide lateral support to the valve stem 23 and help maintain alignment of the valve stem 23 with respect to the longitudinal portion 30 of the valve body housing 20.

[0102] A wiper seal 51 may be provided between the upper end 31 and the valve stem 23. The wiper seal 51 may function to provide a fluid seal between the valve stem 23 and the valve body housing 20 to prevent washcoat from leaking out of the upper end 31 during use. The wiper seal 51 may be configured as a slidable seal capable of maintaining a fluid-tight seal during reciprocal movement of the valve stem 23 relative to the wiper seal 51.

[0103] The functions of the rod seal or bushing 50 and the wiper seal 51 may be combined into a single seal component.

[0104] The rod seal or bushing 50 and / or wiper seal 51, and / or the single seal component may be formed from, for example, EPDM, a fluoroelastomer (eg, Viton®), or polyurethane.

[0105] The valve chamber 37 may comprise at least a portion of the interior of the valve body housing 20. The valve chamber 37 may comprise at least a portion of the hollow bore of the longitudinal portion 30 and the lateral portion 33.

[0106] In some examples, a portion of the boundary of the valve chamber 37 may be defined by the valve body housing 20. Another portion of the boundary of the valve chamber 37 may be defined by the intersection of the seal 51 and the valve stem 23. Another portion of the boundary of the valve chamber 37 may be defined by the intersection of the valve stem seal 64 and the valve seat 24. Another portion of the boundary of the valve chamber 37 may be defined by an inlet valve provided to seal the inlet 35. Such an inlet valve may form part of the valve assembly 4. Alternatively, the inlet valve may be provided within a component coupled to the inlet 35 of the valve assembly 4, or may be provided within the conduit 3 or source 2 itself.

[0107] Together, the valve stem 23 and valve seat 24 may function as an outlet valve movable between closed and open positions to control the flow of washcoat out of the outlet 36. The outlet valve may comprise a reverse poppet valve.

[0108] In the outlet valve closed state, the valve stem seal 64 can seal against the sealing surface 70 to close the aperture 73. In the outlet valve open state, the valve stem seal 64 can disengage from the sealing surface 70 to open the aperture 73.

[0109] The valve assembly 4 is configured to create a pressure drop within the valve chamber 37 when the outlet valve moves from its open state to its closed state. In some examples, this may include the valve stem 23 functioning as a piston within the valve chamber 37. Thus, the valve stem 23 may be considered a valve piston.

[0110] For example, FIG. 2 shows the outlet valve in a closed state. To expel washcoat from outlet 36 (in the direction of arrow B) into the washcoat showerhead 5, the valve stem 23 must move downward relative to the valve seat 24, disengaging the valve stem seal 64 from the sealing surface 70. During this movement, the valve stem 23 extends toward the outlet 36. In addition, the inlet valve must be open to allow washcoat to enter the valve body housing 20 through inlet 35. The source 2 may then be activated to transport the washcoat along the conduit 3 into the valve chamber 37, through inlet 35 (in the direction of arrow A), through the aperture 73 in the valve seat 24, and out the outlet 36 into the washcoat showerhead 5, which is positioned downstream of the valve assembly 4.

[0111] When it is desired to stop the discharge of washcoat, the inlet valve may be closed to stop the transport of additional washcoat into inlet 35. Additionally, closing the inlet valve also creates a fluid-tight seal at or upstream of inlet 35, preventing washcoat present in valve chamber 37 from flowing back through inlet 35.

[0112] Additionally, simultaneously with or subsequent to closing the inlet valve, the outlet valve may be closed by moving the valve stem 23 upwardly by the valve stem actuator 21 to engage the valve stem seal 64 against the sealing surface 70 of the valve seat 24. In particular, the valve stem 23 may be configured to be pulled by the valve stem actuator 21 into sealing engagement with the valve seat 24 in the outlet valve closed state.

[0113] The valve stem 23 may function as a valve piston, such that upward movement of the valve stem 23 causes a pressure drop in the valve chamber 37. The washcoat showerhead 5 may be fluid-tightly coupled to the valve assembly 4. Thus, a pressure drop in the valve chamber 37 may also cause a pressure drop in the washcoat showerhead 5.

[0114] An example of a washcoat showerhead 5 according to the present disclosure is shown in Figures 4-6. The washcoat showerhead 5 may include a housing 100 including an upper layer 101 having a fluid connection to the outlet 36 of the valve assembly 4 and a lower layer 102 including an array of apertures 121 for discharging the washcoat toward the upper surface 12 of the substrate 10.

[0115] The fluid connection may include a conduit 104 provided with a flange 105 sized and shaped to sealingly mate with flange 80 of valve assembly 4. Conduit 104 may define an inlet to the interior of washcoat showerhead 5, which may be located on a central axis of washcoat showerhead 5.

[0116] The top layer 101 may comprise a body 110 provided with a central aperture 111 that may be aligned with the conduit 104 .

[0117] The bottom layer 102 may comprise a body 120 including an array of apertures 121. The array of apertures 121 may comprise a plurality of equally spaced apertures. The apertures may be arranged in a regular pattern such as that shown in Figure 5. The regular pattern may be a hexagonal pattern of apertures, where each aperture is surrounded by six apertures.

[0118] The inner diameter of each aperture may be between 1.5 and 2.5 mm, optionally about 2 mm, optionally 2 mm.

[0119] Each aperture may be defined by a tubular insert 122. The tubular insert 122 may be formed from stainless steel, such as grade 316 stainless steel. The inner diameter of the tubular insert 122 may define the inner diameter of the aperture and may be 1.5 to 2.5 mm, optionally about 2 mm, optionally 2 mm. The tubular insert 122 may extend below the lower surface 124 of the lower layer 102. It has been found that extending the tubular insert 122 below the lower surface 124 of the lower layer 102 is beneficial because it helps prevent washcoat from adhering to the surface of the lower surface 124. Washcoat that adheres to the lower surface 124 near the aperture may accumulate and at least partially block the aperture, leading to uneven deposition of the washcoat on the upper surface 12 of the substrate 10. Additionally, buildup of washcoat on the lower surface 124 may dry and harden and flake or fall off onto the upper surface 12 of the substrate 10, potentially blocking one or more channels in the substrate 10 and / or reducing the aesthetics of the final product. Preferably, the tubular insert 122 may extend below the lower surface 124 of the underlayer 102 by at least 1 mm, more preferably at least 2 mm, and most preferably at least 5 mm, or about 5 mm, or 5 mm.

[0120] The washcoat showerhead 5 may further include a baffle layer 103 configured to direct washcoat flowing into the center of the upper portion 106 of the interior toward the outer edge of the interior. The baffle layer 103 may be configured to transport the washcoat to the lower portion 107 of the interior at or near the outer edge of the interior so that the washcoat can continue to be directed to flow inward toward the center of the lower layer 102 across the upper surface 123 of the lower layer 102. To this end, the baffle layer 103 may include one or more transfer apertures 131, as shown in FIG. 6 . The one or more transfer apertures 131 may be positioned near the outer edge of the baffle layer 103. Each transfer aperture 131 may comprise an arcuate aperture. Three, four, five, or more transfer apertures 131 may be provided.

[0121] The upper layer 101, the lower layer 102, and the baffle layer 103 may be connected together using fasteners, such as bolts, that pass through bolt holes in each layer, as shown in the exploded view of FIG. 4 . The upper layer 101, the baffle layer 103, and the lower layer 102 may be sealed together. Thus, the housing of the washcoat showerhead 5 may be liquid-tight except for the inlet defined by the conduit 104 and the outlet defined by the array of apertures 121. In this manner, a pressure drop within the valve chamber 37 of the valve assembly 4 may also create a pressure drop within the housing of the washcoat showerhead 5. In particular, a pressure drop within the valve chamber 37 of the valve assembly 4 may also create a pressure drop at the top end of each aperture in the array of apertures 121. For example, at least a first O-ring seal 108 may be provided between the upper layer 101 and the baffle layer 103, and at least a second O-ring seal 109 may be provided between the baffle layer 103 and the lower layer 102.

[0122] The top layer 101, bottom layer 102, and baffle layer 103 may be formed from a metal, such as stainless steel, or an engineering plastic, such as POM (polyoxymethylene).

[0123] When assembled together, the top layer 101 and the baffle layer 103 may be separated by a first gap, optionally the first gap may be 3.0-5.0 mm, optionally about 4.0 mm, optionally 4.0 mm. The baffle layer 103 and the bottom layer 102 may be separated by a second gap, optionally the second gap may be 3.0-5.0 mm, optionally about 4.0 mm, optionally 4.0 mm.

[0124] In use, the substrate 10 may first be engaged with the headset 6 of the substrate-coating apparatus 1 so that the upper surface 12 of the substrate 10 is positioned below the washcoat showerhead 5. The washcoat may then be transported from the washcoat source 2 toward the washcoat showerhead 5. The valve assembly 4 may be used to control the flow of the washcoat from the source 2 into the interior of the washcoat showerhead 5. Thus, the washcoat may be dispensed from the washcoat showerhead 5 onto the upper surface 12 of the substrate 10. The washcoat may then be drawn through the substrate 10 by applying a suction force to the lower surface 13 of the substrate 10. The outlet valve of the valve assembly 4 may be moved between its closed state and its open state to control the flow of the washcoat into the interior of the washcoat showerhead 5. When the outlet valve is moved from its open state to its closed state, a pressure drop is created within the washcoat showerhead 5. This pressure drop can advantageously act to mitigate dripping and / or leakage of washcoat from the apertures of the washcoat showerhead 5 by creating a suction force at the top end of each of the array of apertures 121 (or tubular inserts 122, if present).

[0125] FIG. 7 shows a second embodiment of a valve assembly 4 for a substrate coating apparatus 1. Features of the valve assembly 4 that are the same or substantially the same as the valve assembly 4 of FIGS. 2 and 3 are referred to by the same reference numerals and will not be described in further detail. Reference is made to the above description. Additionally, this second embodiment of the valve assembly 4 may be used in the same substrate coating apparatus 1 as described above in place of the first embodiment of the valve assembly 4. Accordingly, other portions of the substrate coating apparatus 1 will not be described further. Reference is made to the above description.

[0126] As described above, the second embodiment of the valve assembly 4 may include a valve body housing 20, a valve stem actuator 21, a valve stem 23, and a valve seat 24.

[0127] The valve body housing 20 may be formed from fewer separate components than in the first embodiment. For example, the flange 80 and the valve seat 24 may be integrated as part of the longitudinal portion 30. The valve seat 24 may comprise an annular surface of the longitudinal portion 30. The annular surface may face forward, i.e., toward the outlet 36.

[0128] Additionally or alternatively, the valve stem actuator 21 may be directly coupled to the upper end 31 of the valve body housing 20 without an intervening actuator connection.

[0129] Additionally or alternatively, the actuator stem 41 of the valve stem actuator 21 may be coupled to the upper portion 60 of the valve stem 23 by a fastener, such as a bolt, engaged between the bolt holes 200 and 201 of the valve stem actuator 21 and the valve stem 23, respectively. The use of a fastener may eliminate the need for busing to maintain alignment of the valve stem 23 as in the first embodiment.

[0130] Additionally or alternatively, one or more sliding seals 202, 204 may be provided on the valve stem 23 for sealing the upper portion 60 against the longitudinal portion 30 of the valve body housing 20. Two sliding seals 202, 204 may be provided. Each sliding seal 202, 204 may be an O-ring seal. Each sliding seal 202, 204 may be disposed within annular recesses 203, 205 in the upper portion 60.

[0131] Additionally or alternatively, the enlarged valve stem head 63 of the valve stem 23 may be a separate part connected to the remainder of the valve stem 23 by fasteners, such as bolts, engaged between the bolt holes 207 and 206 of the lower portion 61 and the enlarged valve stem head 63, respectively.

[0132] Additionally or alternatively, the valve stem seal 64 may be disposed within an annular recess 210 in the rearward-facing surface of the enlarged valve stem head 63 , i.e., the surface facing away from the outlet 36 .

[0133] The inlet 35 may be provided with a gasket seal 208 for sealing engagement with the conduit 3. The outlet 36 may be provided with a gasket seal 209 for sealing engagement with the washcoat showerhead 5.

[0134] The operation of the second embodiment of the valve assembly 4 is substantially the same as that of the first embodiment described above. [Example]

[0135] The following example compares the operation of the valve assembly 4 and / or washcoat showerhead 5 of the present disclosure, as described above and shown in FIG. 2, with the operation of the valve assembly 4' and / or washcoat showerhead 5' not according to the present disclosure, as described above.

[0136] A comparative valve assembly 4' is shown in FIG. 8. Its design is similar to the valve assembly 4 shown in FIG. 2. Specifically, the valve assembly 4' includes a valve body housing 20', a valve stem actuator 21', a valve stem 23', and a valve seat 24'. The valve stem 23' is associated with a valve stem seal 64'. The valve seat 24' defines a sealing surface 70' engaged by the valve stem seal 64'. The valve assembly 4' includes an inlet 35' for receiving washcoat and an outlet 36' for delivering washcoat to the washcoat showerhead. In contrast to the valve assembly 4 of the present disclosure described above, the valve stem 23' of the valve assembly 4' of FIG. 8 is moved downward by the valve stem actuator 21' to engage the valve stem seal 64' against the sealing surface 70' of the valve seat 24'. Notably, in the closed state of the valve assembly 4', the valve stem 23' is pushed into sealing engagement with the valve seat 24'.

[0137] A comparative washcoat showerhead 5' is shown in Figure 9. The washcoat showerhead 5' comprises a housing 100' comprising an upper layer 101' having fluid connections for receiving the washcoat and a lower layer 102' comprising an array of apertures 121' for dispensing the washcoat. Each aperture 121' is defined by a tubular insert 122'. The tubular inserts 122' extend a distance of 1-2 mm below the lower surface 124' of the lower layer 102'.

[0138] In the following example, a series of three predetermined shots of washcoat were dispensed onto the upper surfaces of a series of substrates, each substrate receiving one shot of washcoat. The first washcoat had a 34% solids content and a viscosity of 3000-3400 cP. The second washcoat had a 40% solids content and a viscosity of 2000-2500 cP. The third washcoat had a solids content of less than 1% and a viscosity of 700-1200 cP.

[0139] Example 1 The comparative valve assembly 4' and comparative washcoat showerhead 5' were tested in combination. The number of drops observed after each shot of washcoat was dispensed. When a third washcoat having a viscosity of 700-1200 cP was used, a total of 50 drops of washcoat were observed to drip from aperture 121'. When a first washcoat having a viscosity of 3000-3400 cP was used, a total of 30 drops of washcoat were observed to drip from aperture 121'. When a second washcoat having a viscosity of 2000-2500 cP was used, the number of drops observed was 30-50.

[0140] Example 2 The combination of the comparative valve assembly 4' and the washcoat showerhead 5 of the present disclosure was tested. The number of drops was observed after dispensing each shot of washcoat. When a third washcoat having a viscosity of 700-1200 cP was used, a total of 40 drops of washcoat were observed to drop from the aperture 121. When a first washcoat having a viscosity of 3000-3400 cP was used, a total of 20 drops of washcoat were observed to drop from the aperture 121. When a second washcoat having a viscosity of 2000-2500 cP was used, the number of drops observed was 20-40.

[0141] Example 3 The combination of the valve assembly 4 of the present disclosure and the comparative washcoat showerhead 5' was tested. The number of drops was observed after dispensing each shot of washcoat. When a third washcoat having a viscosity of 700-1200 cP was used, a total of 10 drops of washcoat were observed to drip from the aperture 121'. When a first washcoat having a viscosity of 3000-3400 cP was used, a total of 5 drops of washcoat were observed to drip from the aperture 121'. When a second washcoat having a viscosity of 2000-2500 cP was used, the number of drops observed was 5-10.

[0142] Example 4 A combination of the disclosed valve assembly 4 and the disclosed washcoat showerhead 5 was tested. After the dispensing of each shot of washcoat, a total of 0-2 drops of washcoat were observed dripping from the aperture 121 for each of the first, second, and third washcoats.

[0143] As can be seen by comparing Example 1 and Example 2, the use of the washcoat showerhead 5 of the present disclosure was found to have some limited benefit in reducing the amount of dripping when combined with the comparative valve assembly 4'.

[0144] As can be seen by comparing Examples 1 and 3, the use of the valve assembly 4 of the present disclosure was found to have a significant benefit in reducing the amount of dripping when combined with the comparative washcoat showerhead 5'. Without being bound by theory, it is believed that the pressure drop that occurs when the valve assembly 4 is closed helps to create a suction force that reduces the dripping of the washcoat.

[0145] However, as can be seen by comparing Example 4 with the other examples, the most beneficial results were found when the disclosed valve assembly 4 was combined with the disclosed washcoat showerhead 5. With this combination, the dripping problem was substantially or completely eliminated for a variety of washcoats of varying viscosities. Without being bound by theory, it is believed that the pressure drop created upon closing of the valve assembly 4, combined with the use of the baffle layer 103 and / or tubular insert 122, helps to create a more effective suction force across the array of apertures 121, which reduces or eliminates dripping of the washcoat.

[0146] Further aspects and embodiments of the present disclosure are described in the following clauses.

[0147] Clause 1. A method of coating a substrate with a washcoat, the method comprising: engaging the substrate with a head set of the substrate coating apparatus such that the upper surface of the substrate is positioned under a washcoat showerhead of the substrate coating apparatus; transporting washcoat from a washcoat source toward a washcoat showerhead; controlling the flow of washcoat from a supply to an interior of the washcoat showerhead using a valve assembly; Discharging a washcoat from a washcoat showerhead toward an upper surface of a substrate; and drawing the washcoat through the substrate by applying a suction force to a lower surface of the substrate; The method includes a valve assembly including an outlet valve movable between a closed state and an open state to control the flow of washcoat into the interior of the washcoat showerhead, the valve assembly creating a pressure drop within the washcoat showerhead when the outlet valve moves from its open state to its closed state.

[0148] Clause 2. The method of clause 1, wherein the outlet valve comprises a valve stem that reciprocates against a valve seat.

[0149] Clause 3. The method of clause 2, wherein the valve stem or a valve seal provided on the valve stem sealingly engages the valve seat in the closed state of the outlet valve.

[0150] Clause 4. The method of clause 2 or 3, wherein the valve stem or a valve seal provided on the valve stem sealingly engages the downstream face of the valve seat in the closed state of the outlet valve.

[0151] Clause 5. The method of any one of clauses 2 to 4, wherein the valve stem or valve seal is pulled into sealing engagement with the valve seat in the closed state of the outlet valve.

[0152] Clause 6. The method of any one of clauses 2-5, wherein the valve stem extends through the valve seat in both the open and closed states.

[0153] Clause 7. The method of any one of clauses 2 to 6, wherein a pressure drop is created within a valve chamber of the valve assembly when the valve assembly moves from an open state to a closed state.

[0154] Clause 8. The method of clause 7, wherein the valve stem acts as a piston within the valve chamber, creating a pressure drop within the valve chamber as it moves from an open state to a closed state.

[0155] Clause 9. The method of clause 7 or 8, wherein the valve stem extends toward the outlet when the outlet valve moves to its open state and retracts away from the outlet when the outlet valve moves to its closed state.

[0156] Clause 10. The method of any one of clauses 7 to 9, wherein the volume of the valve chamber capable of accommodating the washcoat is greater in the outlet valve closed state than in the outlet valve open state.

[0157] Clause 11. A method according to any one of clauses 2 to 10, wherein the valve stem is moved by a valve stem actuator, optionally the valve stem actuator being a pneumatic, hydraulic or electromechanical actuator.

[0158] Clause 12. The method of any one of clauses 1-11, wherein in the washcoat showerhead, the washcoat enters the center of the upper interior, then flows toward the outer edge of the interior, then is directed downward to enter the lower interior, and then at the lower portion is directed to flow inward toward the center of the washcoat showerhead.

[0159] Clause 13. The method of clause 12, wherein the washcoat is ejected from a lower interior portion through an array of apertures disposed in a lower layer of the washcoat showerhead.

[0160] Clause 14. A substrate coating apparatus comprising: a source of washcoat; a washcoat showerhead for dispensing the washcoat toward an upper surface of the substrate; a head set for engaging the substrate so as to position an upper surface of the substrate under the washcoat showerhead; a vacuum generator for sucking the washcoat discharged from the washcoat showerhead through the substrate; The substrate coating apparatus further comprises a valve assembly for controlling the flow of the washcoat into the washcoat showerhead, the valve assembly comprising: an inlet for receiving washcoat provided from a washcoat supply; an outlet for delivering the washcoat to the shower head; an outlet valve movable between a closed state and an open state to control the flow of washcoat out of the outlet; The substrate coating apparatus, wherein the valve assembly is configured to create a pressure drop within the washcoat showerhead when the outlet valve moves from its open state to its closed state.

[0161] Clause 15. The substrate coating apparatus of clause 14, wherein the outlet valve comprises a valve stem configured for reciprocating movement relative to a valve seat.

[0162] Clause 16. A substrate coating apparatus as described in clause 15, wherein the valve stem or a valve seal provided on the valve stem is configured to sealingly engage the valve seat in a closed state of the outlet valve.

[0163] Clause 17. A substrate coating apparatus according to clause 15 or 16, wherein the valve stem or a valve seal provided on the valve stem is configured to sealingly engage a downstream surface of the valve seat in a closed state of the outlet valve.

[0164] Clause 18. A substrate coating apparatus as described in any one of clauses 15 to 17, wherein the valve stem or valve seal is configured to be pulled by the valve stem actuator into sealing engagement with the valve seat in the closed state of the outlet valve.

[0165] Clause 19. A substrate coating apparatus according to any one of clauses 15 to 18, wherein the valve stem extends through the valve seat in both the open and closed positions.

[0166] Clause 20. The substrate coating apparatus of any one of clauses 15 to 19, wherein the valve assembly further comprises a valve chamber.

[0167] Clause 21. The substrate coating apparatus of clause 20, wherein the valve assembly is configured to create a pressure drop within the valve chamber when moving from an open state to a closed state.

[0168] Clause 22. A substrate coating apparatus as described in clause 20 or 21, wherein the valve stem is configured to act as a piston within the valve chamber to create a pressure drop within the valve chamber when moving from an open state to a closed state.

[0169] Clause 23. A substrate coating apparatus according to any one of clauses 20 to 22, wherein the valve chamber of the valve assembly is fluid-tight sealed to the interior of the washcoat showerhead.

[0170] Clause 24. A substrate coating apparatus as described in any one of clauses 20 to 23, wherein the valve stem extends toward the outlet when the outlet valve moves to its open state and retracts away from the outlet when the outlet valve moves to its closed state.

[0171] Clause 25. A substrate coating apparatus as described in any one of clauses 20 to 24, wherein the valve assembly is configured such that the volume of the valve chamber capable of accommodating the washcoat is greater in a closed outlet valve position than in an open outlet valve position.

[0172] Clause 26. A substrate coating apparatus as described in any one of clauses 15 to 25, wherein the valve stem comprises an enlarged valve stem head and a valve stem seal disposed adjacent to a proximal surface of the enlarged valve stem head.

[0173] Clause 27. The substrate coating apparatus of clause 26, wherein the enlarged valve stem head is positioned downstream of the valve seat in both the open and closed positions.

[0174] Clause 28. A substrate coating apparatus according to clause 26 or 27, wherein the valve stem seal comprises an O-ring, optionally an EPDM O-ring.

[0175] Clause 29. A substrate coating apparatus according to any one of clauses 14 to 28, further comprising a valve stem actuator, optionally the valve stem actuator being a pneumatic, hydraulic or electromechanical actuator.

[0176] Clause 30. A substrate coating apparatus as described in any one of clauses 14 to 29, wherein the washcoat showerhead comprises a housing having an upper layer having a fluid connection to an outlet of the valve assembly and a lower layer having an array of apertures for ejecting the washcoat toward the upper surface of the substrate.

[0177] Clause 31. A substrate coating apparatus according to clause 30, wherein the array of apertures comprises a plurality of equally spaced apertures.

[0178] Clause 32. A substrate coating apparatus according to clause 30 or 31, wherein the or each aperture has an internal diameter of between 1.5 and 2.5mm, optionally about 2mm, optionally 2mm.

[0179] Clause 33. A substrate coating apparatus according to any one of clauses 30 to 32, wherein the or each aperture is defined by a tubular insert.

[0180] Clause 34. A substrate coating apparatus according to clause 33, wherein the tubular insert of the or each aperture extends below the lower surface of the underlying layer by at least 1 mm, more preferably at least 2 mm, most preferably at least 5 mm, or about 5 mm, or 5 mm.

[0181] Clause 35. A substrate coating apparatus according to any one of clauses 30 to 34, wherein the washcoat showerhead further comprises a baffle layer configured to direct the washcoat flowing into the center of the upper part of the interior toward the outer edge of the interior.

[0182] Clause 36. A substrate coating apparatus as described in clause 35, wherein the baffle layer is configured to transport the washcoat to a lower portion of the interior at or near the outer edge of the interior so that the washcoat is directed to continue to flow inward across the upper surface of the lower layer toward the center of the lower layer.

[0183] Clause 37. The substrate coating apparatus of clause 35 or 36, wherein the top layer and the baffle layer are separated by a first gap, optionally the first gap is 3.0 to 5.0 mm, optionally about 4.0 mm, optionally 4.0 mm.

[0184] Clause 38. A substrate coating apparatus according to any one of clauses 35 to 37, wherein the baffle layer and the lower layer are separated by a second gap, optionally the second gap being between 3.0 and 5.0 mm, optionally about 4.0 mm, optionally 4.0 mm.

[0185] Clause 39. A substrate coating apparatus as described in any one of clauses 35 to 38, wherein the upper layer, baffle layer, and lower layer are sealed together, optionally comprising at least a first O-ring seal between the upper layer and the baffle layer, and a second O-ring seal between the baffle layer and the lower layer.

[0186] Clause 40. A substrate coating apparatus according to any one of clauses 14 to 39, wherein the outlet valve comprises a reverse poppet valve.

[0187] Clause 41. A valve assembly for a substrate coating apparatus, the valve assembly comprising: A valve chamber; an entrance for receiving wash coats; an outlet for delivering the washcoat to the shower head; an outlet valve movable between a closed state and an open state to control the flow of washcoat out of the outlet; The valve assembly is configured to create a pressure drop in the valve chamber when the outlet valve moves from its open state to its closed state.

[0188] Clause 42. The valve assembly of clause 41, wherein the outlet valve comprises a valve stem configured for reciprocating movement relative to a valve seat.

[0189] Clause 43. A valve assembly as described in clause 42, wherein the valve stem is configured to act as a piston within the valve chamber to create a pressure drop within the valve chamber when moving from an open state to a closed state.

[0190] Clause 44. A valve assembly as described in clause 42 or 43, wherein the valve stem or a valve seal provided on the valve stem is configured to sealingly engage the valve seat in the outlet valve closed state.

[0191] Clause 45. A valve assembly as described in clause 44, wherein the valve stem or a valve seal provided on the valve stem is configured to sealingly engage a downstream surface of the valve seat in a closed state of the outlet valve.

[0192] Clause 46. A valve assembly as described in clause 44 or 45, wherein the valve stem or valve seal is configured to be pulled by the valve stem actuator into sealing engagement with the valve seat in the outlet valve closed state.

[0193] Clause 47. A valve assembly according to any one of clauses 42 to 46, wherein the valve stem extends through the valve seat in both the open and closed positions.

[0194] Clause 48. A valve assembly as claimed in any one of clauses 42 to 47, wherein the valve stem extends towards the outlet when the outlet valve moves to its open state and retracts away from the outlet when the outlet valve moves to its closed state.

[0195] Clause 49. A valve assembly described in any one of clauses 42 to 48, wherein the valve stem comprises an enlarged valve stem head and a valve stem seal disposed adjacent to the proximal surface of the enlarged valve stem head.

[0196] Clause 50. The valve assembly of clause 49, wherein the enlarged valve stem head is disposed downstream of the valve seat in both the open and closed positions.

[0197] Clause 51. A valve assembly according to clause 49 or 50, wherein the valve stem seal comprises an O-ring, optionally an EPDM O-ring.

[0198] Clause 52. A valve assembly according to any one of clauses 41 to 51, wherein the valve assembly further comprises a valve stem actuator, optionally the valve stem actuator being a pneumatic, hydraulic or electromechanical actuator.

[0199] Clause 53. A valve assembly according to any one of clauses 41 to 52, wherein the outlet valve comprises a poppet valve.

[0200] Clause 54. The method of any one of clauses 1 to 13, wherein the substrate is selected from a flow-through substrate (e.g., a monolithic flow-through substrate) or a filter substrate (e.g., a wall-flow filter substrate).

[0201] Clause 55. The method of any one of clauses 1-13, wherein the washcoat comprises a catalytic coating selected from a three-way catalyst (TWC), a selective catalytic reduction (SCR) catalyst, a diesel oxidation catalyst (DOC), a lean NOx trap catalyst (LNT), an ammonia slip catalyst (ASC), a combined selective catalytic reduction catalyst and ammonia slip catalyst (SCR / ASC), or a passive NOx adsorber (PNA).

[0202] Clause 56. The method of any one of clauses 1-13, wherein the washcoat has a viscosity of 3-9000 cP, optionally 3-54 cP, optionally 32-576 cP, optionally 23-422 cP, optionally 250-4500 cP, optionally 500-9000 cP.

Claims

1. 1. A method of coating a substrate with a washcoat, comprising: engaging the substrate with a head set of the substrate coating apparatus such that an upper surface of the substrate is positioned under a washcoat showerhead of the substrate coating apparatus; transporting washcoat from a source of washcoat toward the washcoat showerhead; controlling the flow of the washcoat from the source to the interior of the washcoat showerhead using a valve assembly; ejecting the washcoat from the washcoat showerhead toward the upper surface of the substrate; and drawing the washcoat through the substrate by applying a suction force to a lower surface of the substrate; the valve assembly includes an outlet valve movable between a closed state and an open state to control the flow of washcoat into the interior of the washcoat showerhead, the valve assembly creating a pressure drop within the washcoat showerhead when the outlet valve moves from the open state to the closed state, thereby reducing or preventing dripping or leakage of the washcoat; the outlet valve including a valve stem that reciprocates against a valve seat; creating a pressure drop within a valve chamber of the valve assembly when the valve assembly moves from the open state to the closed state; and The method wherein the valve stem acts as a piston within the valve chamber, creating a pressure drop within the valve chamber as it moves from the open state to the closed state.

2. The method described in claim 1, wherein the valve stem or a valve seat provided on the valve stem sealingly engages with the valve seat when the outlet valve is in a closed state.

3. 3. The method of claim 1 or 2, wherein in the washcoat showerhead, the washcoat enters the center of an upper portion of the interior, then flows toward the outer edge of the interior, then is directed downward to enter a lower portion of the interior, and then is directed in the lower portion to flow inward toward the center of the washcoat showerhead.

4. 1. A substrate coating apparatus comprising: a source of washcoat; a washcoat showerhead for discharging the washcoat toward an upper surface of a substrate; a head set for engaging the substrate to position the upper surface of the substrate under the washcoat showerhead; a vacuum generator for sucking the washcoat discharged from the washcoat showerhead through the substrate; The substrate coating apparatus further comprises a valve assembly for controlling the flow of washcoat into the washcoat showerhead, the valve assembly comprising: an inlet for receiving said washcoat from said source of washcoat; an outlet for delivering the washcoat to the showerhead; an outlet valve movable between a closed state and an open state to control the flow of washcoat out of the outlet; the valve assembly is configured to reduce or prevent dripping or leakage of the washcoat by creating a pressure drop within the washcoat showerhead when the outlet valve moves from the open state to the closed state; the outlet valve comprising a valve stem configured for reciprocating movement relative to a valve seat; the valve assembly further comprising a valve chamber; and The substrate coating apparatus, wherein the valve stem is configured to act as a piston within the valve chamber to create a pressure drop within the valve chamber when moving from the open state to the closed state.

5. A substrate coating apparatus as described in claim 4, wherein the valve stem or a valve seat provided on the valve stem is configured to be pulled and sealingly engage with the valve seat when the outlet valve is in a closed state.

6. 5. The substrate coating apparatus of claim 4, wherein the valve chamber of the valve assembly is fluid-tight sealed to the interior of the washcoat showerhead.

7. 7. The substrate coating apparatus of claim 4, wherein the washcoat showerhead comprises a housing comprising an upper layer having a fluid connection to the outlet of the valve assembly, and a lower layer comprising an array of apertures for ejecting the washcoat toward the upper surface of a substrate.

8. 8. The substrate coating apparatus of claim 7, wherein the washcoat showerhead further comprises a baffle layer configured to direct the washcoat flowing into the center of the upper portion of the interior toward an outer edge of the interior.

Images