Patent Application
20060283157
The present invention is directed to a rotary filter screen assembly for engine air and in particular to a rotating filter screen assembly having an upstream vacuum cleaning chamber and a downstream aerodynamic baffle plate.
The engines of large working vehicles, such as self-propelled agricultural combines, are commonly enclosed. Typically, the enclosures are provided with rotating self-cleaning filter screens through which cooling and combustion air streams are drawn by a downstream engine fan. Heat exchangers are located downstream of the filter screen and include the radiator for cooling the engine, the oil cooler, and the condenser coils for the air conditioning. The rotating filter screen is used to remove debris such as chaff and leaves from the cooling and combustion air streams so that the debris does not block the various heat exchangers or the combustion air filters located downstream of the filter screen.
The rotating filter screen is rotate through a screen cleaner to automatically and continuously provide a clean air flow through the filter screen. Typically, a screen cleaner includes a vacuum cleaning chamber on the upstream side of the screen. The cleaning chamber is pneumatically coupled by a duct to a vacuum source generated by the engine. The duct is coupled to the engine air stream downstream of the heat exchangers for reintroducing the debris collected off the upstream side of the filter screen into the air stream prior to exhaust.
The performance and efficiency of the vacuum cleaning chamber can be increased with a baffle plate on the downstream side of the rotating screen. The cleaning chamber works in conjunction with the vacuum generated by the engine fan to remove collected debris from the upstream side of the filter screen. Generally a flat baffle plate cuts off and diverts the air flow in the vicinity of the cleaning chamber.
However, due to increasing regulatory requirements, such as the Tier 3 emissions requirements, the power and cooling demands on today's engines require an increased air flow to the engines. Also, since today's working vehicles, such as combine harvesters, are larger and operating at faster speeds, the environment around the combine, from which the engine cooling and combustion air is drawn, has more debris. Thus, it is necessary to increase the effectiveness of the vacuum cleaning chamber and to increase the amount of debris removed from the filter screen.
A rotating filter screen assembly is provided for filtering debris from cooling and combustion air provided to an engine system having an engine fan adapted to draw air through the filter screen assembly. The filter screen assembly includes a rotating filter screen having an upstream side and a downstream side. The filter screen is adapted to collect debris on the upstream side from air passing through the filter screen. A stationary cleaning chamber is mounted in the filter screen assembly and has an open face adjacent the upstream side of the filter screen. A vacuum source is connected to the cleaning chamber and is adapted to remove collected debris from the upstream side of the filter screen as the filter screen rotates relative to the cleaning chamber. An aerodynamic baffle plate is offset from the downstream side of the filter screen to divert air flow toward the downstream side of the filter screen so as to create an area of high pressure air at the open face of the cleaning chamber.
The filter screen 22 is a flat circular screen having a woven wire mesh. The vacuum cleaning chamber 24 is generally triangular in shape and extends radially across a small portion of the upstream surface of the filter screen 22 from the outer circumferential edge to the center of the circular screen 22. The leading edge of the cleaning chamber 24 often includes a comb 28 having a castellated edge. The castellated edge is provided with a series of notches that cut large debris on the screen into smaller pieces. The trailing edge of the cleaning chamber is provided with a flexible skirt 26 providing a partial seal for the vacuum cleaning chamber 24.
In operation, the filter screen 22 rotates relative to the cleaning chamber 24. The cleaning chamber 24 is thus able to continually clean the complete upstream surface of the filter screen 22 as the screen rotates past. The illustrated self-cleaning rotary filter screen assembly 22 is similar to the one described in U.S. Pat. No. 5,183,487, the disclosure of which is here incorporated by reference. Although the rotating filter screen is illustrated with a stationary cleaning chamber, the present invention may be used with various other configurations where the filter screen and cleaning chamber rotate or move relative to each other.
The flat center portion 32 of the aerodynamic baffle plate substantially covers the transverse width of the cleaning chamber 24. The two additional wing portions 34 are attached at a forward angle to each side of the center potion 32. The wings 34 transversely extend the footprint of the aerodynamic baffle plate 30 beyond the lateral extent of the triangular vacuum cleaning chamber 24. The winged baffle plate 30 improves the cleaning effectiveness of the cleaning chambers by diverting and providing additional air flow across the filter screen to the open face of the vacuum cleaning chamber 24. The aerodynamic baffle plate is offset from the downstream side of the filter screen 22 so as to divert air flow toward the downstream side of the filter screen. The diverted air creates an area of high pressure air along the open face of the vacuum cleaning chamber 24.
The aerodynamic baffle plate has a flat center portion 32 and two wing portions 34 that are angled toward the filter screen 22 and toward the vacuum cleaning chamber 24. The cleaning chamber 24 has a triangular transverse width. The wing portions 34 extend transversely beyond the width of the vacuum cleaning chamber 24 so as to divert addition air to the open face of the cleaning chamber 24.
Having described the illustrated embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.
