Patent Application
20160281538
The disclosure relates to a turbine backplate, and more specifically, relating to remanufacturing of the turbine backplate.
Combustion engines such as diesel engines, gasoline engines, and gaseous fuel-powered engines are supplied with a mixture of air and fuel for combustion within the engine that generates a mechanical power output. In order to maximize the power output generated by this combustion process, the engine is often equipped with a divided exhaust manifold in fluid communication with a turbocharged air induction system.
The divided exhaust manifold increases engine power by helping to preserve exhaust pulse energy generated by the engine's combustion chambers. Preserving the exhaust pulse energy improves the turbocharger's operation, which results in a more efficient use of fuel. In addition, the turbocharged air induction system increases engine power by forcing more air into the combustion chambers than would otherwise be possible. This increased amount of air allows for enhanced fueling that further increases the power output generated by the engine.
However, during use and due to high operating temperatures, components of the turbocharger wear down and need to be replaced. One such component is the backplate and in particular, the sealing surface of the backplate, which can be damaged during use and thus, the backplate needs to be replaced or remanufactured.
U.S. Pat. No. 4,449,714 discloses a method for repairing turbine engine seals and a product manufactured in accordance with the method are provided. A worn or damaged honeycomb seal is removed from a backing plate together with a portion of the surface of the plate. The plate is restored to substantially its original thickness by a low pressure plasma spraying operation which may be followed by further machining to arrive at the required plate thickness. A new seal is then brazed thereon. The finished product will include the backing plate, a low pressure plasma sprayed coated surface, and a honeycomb seal brazed to the coated surface. However, the disclosed process does not provide a way to protect the remaining parts of the backplate from being subjected to the low pressure plasma spray.
Thus, there is a need for an improved process that provides protection to the remaining parts of backplate that are not subjected to the coating process and allow the backplate to be reused.
In one aspect, a method of remanufacturing a back plate of a turbocharger is disclosed and can include cleaning the backplate for a first time, protecting a portion of the backplate, other than a sealing surface from a thermal metal spray with a mask, machining the backplate for a first time, applying a metal to the sealing surface with a thermal metal spray, and machining the backplate for a second time.
In another aspect, a method of remanufacturing a backplate of a turbocharger is disclosed and can include cleaning the backplate for a first time, protecting a portion of the backplate other than a sealing surface from a thermal metal spray with an antibonding agent, machining the backplate for a first time, applying a metal to the sealing surface with a thermal metal spray, and machining the backplate for a second time.
The backplate 106 can support the compressor housing 102 by being bolted thereto. The central housing 108 houses ball bearings and other components and the wheel shroud 110 houses the turbine wheel 112. The turbine wheel 112 converts exhaust energy (heat and pressure) into shaft power to drive the compressor (not shown) via the compressor wheel 104. Turbine wheels are usually made of Inconel or other high temperature alloys to allow them to perform in a temperature environment that regularly exceeds 1200° F. Because the turbine wheel 112 and the compressor wheel 104 are connected via the shaft, they both rotate at substantially the same speed. The turbine housing 114 collects exhaust gases from the engine and directs it to the turbine wheel 112. The turbine housing 114 can be made from iron or steel.
The backplate 106 further separates the compressor housing 102 from the central housing 108. Since the backplate 106 is separate from the compressor housing 102 and the central housing 108, the backplate 106 can be made of a different material including aluminum and various alloys. The backplate 106 provides a sealing surface 122 (
A method of remanufacturing the sealing surface 122 is discussed below (
At step 414, apply thermal metal spray to the backplate 106. Any type of thermal metal spray process can be used such as combustion flame spraying, high velocity oxy-fuel spraying (HVOF), two-wire electric arc spraying, plasma spraying, or vacuum plasma spraying and the like. Further, in one aspect of the disclosure more than one of the thermal metal spray processes may be used in conjunction with each other depending on the conditions of the backplate 106. In combustion flame spraying, the flame is propelled by oxygen mixed with fuel, which also results in melting the metal mixture. The combustion flame spraying uses powder or wire as the main coating mixture component. HVOF is similar to combustion flame spraying, but uses a different torch design that enables the flame to expand when the spray nozzle is engaged. This causes a surge in acceleration, and when the mixture is released from the nozzle, the velocity of the mixture leads to an evenly thin coat. In two-wire electric arc spraying, the deposition relies on an arc-point formed by two electrically conductive wires. Where the wires meet, melting occurs. In plasma spraying, a plasma torch is the primary source of heating and applying the coating. Once the powdered material has been melted, it is subsequently applied to the product in a similar manner as combustion flame spraying. Vacuum plasma spraying is a low temperature method that must be conducted inside a controlled environment, which not only sustains the vacuum but also helps minimize damage to the material. Because the vacuum environment is controlled, it helps ensure a more precise application of the material. Any material that is wear resistant and having high hardness can be thermally sprayed including nickel, nickel based alloys (NiAl, NiCr), stainless steel, Molybdenum MCrAlY's (NiCrAlY, CoCrAlY, NiCoCrAlY, CoNiCrAlY), Titanium (Ti), Stellite, Triballoy and the like. In other aspects of the disclosure, ceramics may be alternatively used.
In one aspect, NiAl or a stainless steel can be used and sprayed onto the backplate for a number of cycles ranging from about 2-8 cycles, each cycle may include about 3-7 passes that applies about 0.050 μm to about 0.090 μm at about 40-70 psi. A robot arm can be used having a travel speed from about 20 mm/sec to about 40 mm/sec and having a standoff from the backplate during spraying from about 3-9 inches. A rotating table having the backplate 106 can rotate the backplate 106 between about 20 rpm to about 45 rpm. The operating voltage can be about 20-40 V and the current about 130-170 A depending on the spraying process used.
At step 416, a final machining of the component or the backplate 106 is conducted to ensure that the backplate is returned to the original manufacturer's specifications. The final machining can be done using any known method including sanding, milling and the like. It should be noted that the machining steps discussed herein can be done with operating parameters such as at ambient temperature between about 60-90° F., at rotational speed about 50-1300 rpm and at a feed rate of about 0.1-1.0 SFM. At step 418, detailing of the component of the backplate 106 to add or remove any remaining features such as part number, logo and the like. At step 420, the component or the backplate 106 is cleaned and polished to remove any residual sprayed materials or from the final machining step. At step 422, confirm that the component or the backplate 106 meets or exceeds the original manufacturer's specification so that it can then be ready to be used in the turbochargers. At step 424, the process ends.
The process described above can be used with any component in any vehicle, device, apparatus and the like that can be remanufactured. Further, the steps in the process do not all have to be performed or performed in any particular order. Some of the steps can be performed at the same time or be combined.
A process of remanufacturing a backplate of turbochargers is provided. Portions of the backplate such as the sealing surface will wear out during use and needs to be returned to the original manufacturer specifications. The sealing surface can prevent any air leaks from the compressor portion of the turbocharger. A thermal metal spray can be used in the remanufacturing process. Any type of thermal spray metal techniques can be used such as combustion flame spraying, high velocity oxy-fuel spraying (HVOF), two-wire electric arc spraying, plasma spraying, and vacuum plasma spraying and the like. The process includes using a mask to cover portions of the backplate that does not need to be thermal metal spray. Alternatively or in addition to, an anti-bonding agent can be used on portions of the backplate that is not subjected to the thermal metal spray. Once the thermal metal spray is applied, additional cleaning and machining can be done to return the backplate to its original manufacturer's specification and for later use in repairs to the turbochargers.
