Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed
Field of the invention
[0001] The present disclosure relates to a pressure pulsation dampener unit for a supply module.
Background of the invention

[0002] An internal combustion engine converts chemical energy present in fuel into mechanical power. As the fuel undergoes combustion within an engine cylinder, it produces exhaust gases containing various pollutants such as unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). These pollutants, if left untreated, can have harmful effects on both human health and the environment.

[0003] To address this issue, an exhaust system is employed to collect and treat the exhaust gases generated by the internal combustion engine. The system starts with an exhaust manifold, which collects the exhaust gas and directs it towards a SCR (selective catalytic reduction) system. The exhaust system serves several functions, including the filtration of pollutants, noise reduction, and the discharge of purified exhaust gases through its outlet. The primary purpose of the SCR system is to convert harmful Nitrous oxide into Water and Nitrogen.

[0004] Among the pollutants present in the exhaust gas, nitrogen oxides (NOx) pose a significant challenge. The SCR system uses an aqueous solution of urea, commonly known as "AdBlue", as a reducing agent to address NOx emissions. The AdBlue solution is introduced into the SCR system, where it undergoes hydrolysis to produce ammonia. In the presence of a SCR catalyst, the ammonia reacts with nitrogen oxides, resulting in their conversion into nitrogen and water. A supply module supplies AdBlue to a dosing module to dose the right amount of AdBlue into an exhaust line.

[0005] The supply module comprises a filter module, a pump unit, at least a heater, a pressure sensor, and a PPD (Pressure Pulsation Dampener) unit, mounted on a supply module housing. The supply module is fixed on or away from a tank containing AdBlue. The AdBlue solution may contain impurities, which are filtered out by a filter module. The pump unit functions to transport AdBlue from the tank to a dosing module, while the PPD unit dampens pressure variations within the supply module.

[0006] In state of the art, the PPD unit comprises of a PPD membrane, a metal piston, a spring, a lock cover, and a PPD housing. In state of the art PPD unit, the PPD membrane is axially sealed on the upper surface of the metal piston due to which a large force is applied axially on the PPD sub-assembly. The lock cover provides pretension force and withstands the re-active force of the spring during working conditions. This limits the piston lift at top dead center. The spring, which is partially enclosed in the metal piston, stores the energy when the system pressure increases and releases the energy when the system pressure decreases.

[0007] In state of the art PPD unit, the metal piston changes the volume within the working chamber by axial movement to regulate and maintain the system pressure. The PPD housing provides guidance and limit the piston at bottom dead center. The functionality of a screw is not only limited to holding the PPD unit over the supply module housing but also to ensure the sealing tightness is established for effective sealing of the PPD membrane. Hence due to this high pressure and aging, the screw loses its effective sealing pressure on the PPD membrane which results in leakage within the supply module. The new idea is to modify the current axial design with minimal design change to the existing components to prevent the leakage of AdBlue and enhance the lifetime of the system.

[0008] The Indian Patent IN02410CH2013 A, A dampener for reducing pressure fluctuations in a fluid supply line of an exhaust after treatment is disclosed. The dampener comprises a piston that can be displaced linearly within a closed volume. The piston of the dampener is displaced using an electric solenoid attached to the dampener. In another embodiment, a method of controlling the dampener for the fluid supply line of the exhaust after treatment system is provided. The method includes the steps of observing pressure readings in the fluid supply line, retrieving a dosing percentage of the exhaust after treatment system and a predetermined set pressure with respect to the fluid supply line, and controlling position of a piston in the dampener, the dampener presents in the fluid supply line based on at least one of: the observed pressure readings, the dosage percentage, and the predetermined set pressure.

Brief description of the accompanying drawings

[0009] An embodiment of the invention is described with reference to the following accompanying drawings:

[0010] Figure 1 depicts a SCR (selective catalytic reduction) system (100) for an internal combustion engine.

[0011] Figure 2 depicts a supply module (200) for a SCR system (100).

[0012] Figure 3 depicts a cross-sectional view of a PPD (Pressure Pulsation Dampener) unit (300) for a supply module (200).

Detailed description of the drawings
[0013] Figure 1 depicts a SCR (selective catalytic reduction) system (100) for an internal combustion engine. The SCR system (100) comprises of a tank (101) filled with an aqueous solution of urea also known as “AdBlue”, a supply module (200) fixed on or away from the tank (101), and at least a dosing module (103) amongst other components known to a person skilled in the art. The SCR system (100) uses AdBlue as the reducing agent which is hydrolyzed into ammonia. The mixture of exhaust gases and ammonia enters a SCR catalyst where nitrogen oxides (NOx) are converted to nitrogen (N2) and water (H2O).
[0014] The AdBlue is made up of 32.5% of urea in water and is stored in the tank (101). The AdBlue is pumped in the supply module (200) to deliver the AdBlue to the dosing module (103) and similar processes known to a person skilled in the art. The main function of the dosing module (103) is to inject AdBlue into an exhaust line in compressed form. The AdBlue is sprayed with different angles and flow rates into the exhaust line that allow the perfect distribution of ammonia in the SCR system (100).
[0015] Figure 2 depicts a supply module (200) for the SCR system (100). The supply module (200) comprises, a filter module (201), a pump unit (202), at least a heater, at least a pressure sensor (102) amongst other components known to a person skilled in the art and a PPD unit (300) located upstream of an outlet channel of the pump unit (202), all enclosed within a supply module housing (203). The SCR system (100) can be damaged by dirt particles present in AdBlue.
[0016] The filter module (201) typically filters out these dirt particles and efficiently protect the SCR system (100) from any wear and thus extend their life. The main function of the pump unit (202) is pumping AdBlue from the tank (101) of the SCR system (100) to the dosing module (103).
[0017] The main function of the heater is to provide heat to the AdBlue when the outside temperature is below a threshold level as AdBlue tend to crystallize below -11 degree Celsius. The pressure sensor (102) is used to determining the pressure of the AdBlue flowing through the supply module (200). The PPD unit (300) regulates the pressure of AdBlue flowing through the supply module (200). The PPD unit (300) is affixed in the supply module (200) through screws (306).
[0018] Figure 3 depicts a cross-sectional view of a PPD (Pressure Pulsation Dampener) unit (300) for a supply module (200). It comprises a PPD membrane (305), a metal piston (304), at least a spring (302), at least a lock cover (301), at least a screw (306), amongst other components known to a person skilled in the art and a PPD housing (303). The metal piston (304) regulates and maintains the system pressure by changing the volume with the working chamber by axial movement. The PPD membrane (305) seals the working chamber from outside environment.
[0019] The spring (302) partially enclosed in the metal piston (304), stores the energy when the system pressure increases and releases the energy when the system pressure decreases, and the similar process known to a person skilled in the art. The lock cover (301) provides pretension spring (302) force and withstands the re-active force of the spring (30) during working condition.
[0020] The PPD housing (304) provides guidance and limits the metal piston (305) at bottom dead center and conducts thermal energy during thawing process. The PPD housing (303) is molded in such a way to accommodate the PPD membrane (305) and provide a uniform sealing force. The PPD membrane (305) follows the axial movement of the metal piston (304) and is radially sealed on the upper surface of the metal piston (304).
[0021] This idea to develop the PPD unit (300) for a supply module (200) is aimed at solving critical issues prevailing in the prior-art. In accordance with the embodiments of the invention described above the radial sealing of the PPD membrane (305) provides less force that is required to mount the PPD sub-assembly with the supply module housing affixed in the supply module (203) compared to the axial sealing of the PPD membrane (305). This new configuration helps in guiding the PPD housing (303) during assembly and prevents the leakage of AdBlue in the supply module (200). Even during aging, the relaxation effect of the screws (306) does not affect the sealing functionality of the PPD membrane (305) and enhances the lifetime of the system.
[0022] It must be understood that the embodiments explained in the above detailed description are only illustrative and do not limit the scope of this invention. Any modification to the PPD unit (300) for a supply module (200) are envisaged and form a part of this invention. The scope of this invention is limited only by the claims.
, Claims:We claim:

1. A PPD (Pressure Pulsation Dampener) unit (300) for a supply module (200), said supply module (200) comprising: a pump unit (202) and at least a supply module housing (203); the PPD unit (300) affixed in the supply module (200) through screws (306), said PPD unit (300) located upstream of an outlet channel of the pump unit (202); said PPD unit (300) comprising: a spring (302) partially enclosed in a metal piston (304); characterized in that PPD unit (300):
a PPD membrane (305) radially sealed on upper surface of the metal piston (304);
a PPD housing (303) molded to accommodate the PPD membrane (305)
2. The PPD unit (300) for a supply module (200) as claimed in claim 1, where the PPD housing (303) is fastened to the supply module housing (203) through screws (306).
3. A supply module (200) for a SCR (selective catalytic reduction) system (100), the supply module (200) fixed on or away from a tank (101) in the SCR (100) system, said supply module (200) receives an aqueous solution from the tank (101); said supply module (200) comprising: a pump unit (202) and at least a supply module housing (203); the PPD unit (300) affixed in the supply module (200) through screws (302), said PPD unit (300) located upstream of an outlet channel of the pump unit (202) ;said PPD unit (300) comprising: a spring (302) partially enclosed in a metal piston (304); characterized in that PPD unit (300):
a PPD membrane (305) radially sealed on upper surface of the metal piston (304);
a PPD housing (303) molded to accommodate the PPD membrane (305)
4. A SCR (selective catalytic reduction) system (100), the SCR system (100) comprising: a tank (101) filled with AdBlue and at least a supply module (200); said supply module (200) comprising: a pump unit (202) and at least a supply module housing (203); the PPD unit (300) affixed in the supply module (200) through screws (306), said PPD unit (300) located upstream of an outlet channel of the pump unit (202); said PPD unit (300) comprising: a spring (302) partially enclosed in a metal piston (304); characterized in that PPD unit (300):
a PPD membrane (305) radially sealed on upper surface of the metal piston (304);
a PPD housing (303) molded to accommodate the PPD membrane (305)