TRANSFER HOSE, ESPECIALLY FOR USE AS AN SCR HOSE

Description

[0001] The invention relates to a transfer hose, which is used particularly at high temperatures and as an SCR hose.

[0002] Reinforced hoses are flexible hoses with an outer layer of reinforcing materials, known as the reinforcement layer. Within this outer layer, such hoses can have multiple layers or strata of different elastomers, thermoplastic elastomers or thermoplastics, and reinforcing materials. The outer layer of reinforcing materials can be braided, knitted, woven, or similar. Textile reinforced hoses are frequently used in low-pressure and / or low-temperature applications (<150°C), for example, as fuel, oil, or compressor hoses. Such a reinforced hose is described, for example, in WO2014 / 019796A1.

[0003] So-called SCR systems are used in practice in commercial vehicles such as trucks and buses, and sometimes also in passenger cars. These systems use an approximately 32.5% aqueous urea solution, the specifications of which are defined in standards such as ISO 22241 and DIN 70070, and which is marketed in Europe under the name AdBlue®. In North America, it is known as Diesel Exhaust Fluid (DEF). Selective catalytic reduction (SCR) is a technology for reducing nitrogen oxides in exhaust gases, for example, from combustion plants, waste incineration plants, gas turbines, industrial plants, and engines. This process uses an SCR catalyst, which selectively reduces nitrogen oxides. Ammonia is required for the reaction and is added to the exhaust gas, for example, in the form of a urea solution.

[0004] In Europe and elsewhere, vehicles must meet increasingly stringent emissions standards. Therefore, a system based on the SCR process has been developed for the exhaust aftertreatment of vehicle engines, particularly diesel engines, to reduce nitrogen oxides in the exhaust gas. In this system, nitrogen oxides present in the exhaust gas are converted into water vapor and nitrogen using a urea solution and the SCR catalyst. The liquid urea solution must be carried in a separate tank and is injected into the exhaust gas via a metering unit through a hose during operation. Such an SCR hose is described, for example, in WO2015 / 022104A1.

[0005] In this design, a heating conductor is arranged between an inner reinforcing layer and the outer rubber. However, such hose constructions are often heavy and have thick walls, which significantly impairs the hose's flexibility. WO 2015 / 022104 A1, for example, discloses SCR hoses that have an inner rubber layer and outer textile braid layers. US 2003 / 178081 A1 discloses liner hoses for transporting fuels that have an inner and an outer rubber layer and an intermediate reinforcing layer. WO 2017 / 092894 A1 discloses liner hoses with a protective layer. DE 10 2018 214615 A1 discloses hoses made of a single layer consisting of a rubber compound, wherein the rubber compound can be a blend of chlorobutyl rubber (CIIR) and EPDM.

[0006] The object of the invention was therefore to provide a transfer hose that is particularly suitable for use in SCR applications and ensures an increased temperature load, especially between 140°C and up to 250°C, from the outside.

[0007] At the same time, the transfer hose should exhibit high flexibility, particularly through reduced weight and thinner walls, to accommodate increasingly confined engine compartments. Additionally, the minimum bending radius should be reduced.

[0008] This problem is solved by a transfer hose according to claim 1, in which an inner layer contains a blend of ethylene propylene diene monomer rubber (EPDM) and chlorobutyl rubber (CIIR).

[0009] Surprisingly, it was found that a transfer hose with an inner layer made of a blend of EPDM and CIIR is characterized by an increased service life at elevated temperatures above 200°C.

[0010] Preferably, the blend, which is often also referred to as a mixture, consists of a ratio of 50 to 90 phr EPDM and 50 to 10 phr CIIR, and particularly preferably of 70 to 90 phr EPDM and 30 to 10 phr CIIR. It goes without saying that the total amount of EPDM and CIIR must always equal 100 phr.

[0011] According to the invention, the relining hose consists of at least one textile relining as an outer layer and at least one inner layer consisting of a rubber compound containing a blend of ethylene propylene diene monomer rubber (EPDM) and chlorobutyl rubber (CIIR) as the only rubber components.

[0012] Preferably, polyphenylene sulfide (PPS) and / or polyoxadiazole (POD) and / or m-aramid (m-AR) and / or p-aramid (p-AR) and / or polyimide (PI) and / or polyetheretherketone (PEEK) and / or polyethylene 2,6-naphthalate (PEN) and / or polyphenylene (PPP) and / or polyphenylene oxide (PPO) and / or polyphenylene sulfide (PPS) and / or polyphenylene ether (PPE) and / or polybenzoxazole (PBO) and / or carbon fibers (CF) and / or metal fibers (MF) and / or glass fibers (GF) can be used alone or in combination as reinforcement for the outer layer. Due to their good temperature resistance, hydrolysis resistance, adhesion, chemical resistance, and processability, PPS and m-aramid are particularly preferred.

[0013] The covering is applied as a textile fabric in the form of braid, corduroy, knit, woven, woven, nonwoven, or laid fabric, preferably as a braid. The covering layer can be single-layered or multi-layered. Preferably, the covering layer has 1 to 5 layers, more preferably 1 to 3 layers, and most preferably 1 to 2 layers.

[0014] The invention will now be explained using an exemplary embodiment with reference to test results.

[0015] Table 1 compares an SCR liner hose according to the invention, consisting of an inner layer made of a blend of EPDM and CIIR and a liner, with an SCR liner hose having an inner layer made of a blend of EPDM and CIIR and an outer layer made of EPDM.

[0016] It turns out that the SCR insert hose is destroyed after aging (internal water temperature 85°C, external air temperature 210°C, 1000h aging with 3 bar flow rate). The elongation at break is now only 65%.

[0017] After aging for 1000 hours, the burst pressure was determined according to DIN 24312. The SCR liner hose has a burst pressure of 50% of its initial value, while the SCR bypass hose has a burst pressure of 100% of its initial value, meaning no degradation has occurred. Table 1 SCR insert hose SCR transfer hose Interior EPDM / CIIR fresh Exterior EPDM fresh Interior EPDM / CIIR after aging Exterior EPDM after aging Interior EPDM / CIIR fresh Interior EPDM / CIIR after aging Shore hardness according to DIN ISO 7619-1 [ShoreA] 65 72 75 76 70 73 Tensile strength according to DIN 53504 [MPa] 9,8 15,0 7,6 7,4 9,8 6,3 Elongation at break according to DIN 53504 [%] 310 265 205 65 280 181 Burst pressure of the hose according to DIN 24312 [bar] 130 69 184 181

Claims

1. A multi-layered hose consisting of at least one textile lining as an outer layer and at least one inner layer consisting of a rubber compound containing a blend of ethylene propylene diene monomer rubber (EPDM) and chlorobutyl rubber (CIIR) as the only rubber components.

2. The multi-layered hose according to claim 1, characterized in that the blend consists of 50 to 90 phr EPDM and 50 to 10 phr CIIR.

3. The multi-layered hose according to claim 2, characterized in that the blend consists of 70 to 90 phr EPDM and 30 to 10 phr CIIR.

4. The multilayer hose according to any one of claims 1 to 3, characterized in that the textile liner is composed of polyphenylene sulfide (PPS) and / or polyoxadiazole (POD) and / or aramid (AR) and / or polyimide (PI) and / or polyetheretherketone (PEEK) and / or polyethylene 2,6-naphthalate (PEN) and / or polyphenylene (PPP) and / or polyphenylene oxide (PPO) and / or polyphenylene ether (PPE) and / or polybenzoxazole (PBO) and / or carbon fibers (CF) and / or metal fibers (MF) and / or glass fibers (GF), either individually or in combination.

5. The multi-layered hose according to any one of claims 1 to 4, characterized in that the hose is free of additional intermediate layers and free of embedded reinforcement layers.

6. A use of a multi-layered hose according to any one of claims 1 to 5 as an SCR (selective catalytic reduction) hose.