Patent Application
20070007061
The invention relates to the structure and operation of cooling systems for vehicles and to methods of supplying intake air to internal combustion engines. More specifically, it relates to a method, system and apparatus for supplying pre-cleaned ambient air to multiple heat exchangers on a vehicle where the heat exchangers are used to form a plenum cooling compartment. A portion of the pre-cleaned air may be used to supply non-preheated air to the engine.
Most mobile construction machines have an above-hood air intake. The above-hood air intake is usually covered by a shield to prevent the entrance of rain and other precipitation. Above-hood air intakes are typically designed to be low profile, i.e., evince a small signature. However, these intakes are required to be high enough to minimize the entry of dust and other debris settling near the hood and far enough from the exhaust stack associated with these machines to minimize the intake of preheated air. Pre-cleaners are typically available for above-hood air intake designs and are used to remove some of the debris from the intake air and, thusly, extend engine air filter life.
Some mobile construction machines are provided with conventional under-hood air intake systems having air intake tubes with inlet openings located in the engine compartment. When these systems have perforations in the hood of the engine compartment, the inlet opening is arranged to prevent the intake of rain and other precipitation. Thus, the inlet opening of the air intake tube is angled such that intake air enters in a direction that is horizontal to or at least partially opposite to the direction of the precipitation as it enters the engine compartment. Other under-hood air intake designs include air intake tubes that are routed to compact cooling package areas where the air inlets are located in areas separate from the engine compartment.
Conventional above-hood air intake systems for work vehicles obstruct visibility for the work vehicle operator. This is a consequence of attempting to meet the noted demands of locating the air intake (1) high enough to eliminate the entry of dust and debris over the hood and (2) far enough from the exhaust stack to eliminate or minimize the intake of preheated air. These disadvantages are only intensified by the pre-cleaners that are often attached to these systems in high debris environments.
A major disadvantage of conventional under-hood air intake systems where the intake port is located in the engine compartment is that they tend to intake preheated air via convection and radiation with respect to the engine. This is accentuated when these systems have perforations in the hood as the intake port must be angled away from the perforations and more toward the engine which preheats the air. In conventional systems where the intake port is located in a compact cooling package area, the intake is restricted and preheated by heat exchangers. Finally, it is not possible to adapt conventional above-hood pre-cleaners to under-hood air intake designs without extensive modifications to such machines.
The invention overcomes each of the above disadvantages by providing an under hood air intake system having an air intake tube routed to an area of a plenum cooling compartment through which ambient air flows. The plenum cooling compartment is formed by a baffle, a floor, a top door, a front door and at least one side door. The baffle separates the plenum cooling compartment from an engine compartment that is separately accessible. The air intake tube is routed to the plenum cooling compartment via the baffle such that the air inlet is located near the baffle in the plenum cooling compartment. Perforations are provided in the at least one side door of the plenum cooling compartment to allow an influx of ambient air and to allow accumulated debris removed from the ambient air, via the perforations, to be removed by gravity. Similar perforations are also provided in the top door. In one exemplary embodiment, a fan draws ambient air into the plenum cooling compartment via the perforations and out of the cooling compartment via at least one heat exchanger. The at least one heat exchanger is located a minimum distance from the inlet opening at the baffle in order to reduce or minimize flow restrictions and the intake of preheated air. The at least one heat exchanger may include multiple heat exchangers forming a fully or partially enclosed heat exchanger package within the plenum cooling compartment.
Embodiments of the invention will be described in detail, with references to the following figures, wherein:
As illustrated in
The plenum cooling compartment is designed such that the gap 109 between the heat exchanger package 108 and the baffle 104 is sufficiently large to reduce or minimize any air flow restrictions and the intake of preheated air. The size of the gap 109 varies with the size and design of the work vehicle.
The perforations 107 are sized to: (1) to block the entrance of airborne debris to the cooling compartment; and (2) to avoid frequent plugging of screens or perforations 107. Perforation sizes for these two somewhat conflicting objectives may be based on many factors, including: the nature and size of the debris, the convenience of the operator, the relative costs of operation, etc. A standard perforation size such as, for example, 3 mm, may be more suitable for work vehicles used in a variety of environments. Thus, a perforation size of about 3 mm is recommended for use in a variety of light debris environments, i.e., environments in which a significant portion of the debris has maximum dimensions greater than about 3 mm.
In environments of extremely heavy debris, i.e., environments in which a significant portion of the debris has maximum dimensions less than about 3 mm, the air intake system may be switched from an under-hood intake of air from the cooling compartment 100 to an above hood intake of air from an above-hood pre-cleaner 250 as shown in
In environments of extremely heavy debris a pressurization option is provided wherein the fan reverses periodically to withdraw air from outside the cooling compartment 100 via the fan door 102 and to force it through the perforations 107 in the hood 101 and the side doors 105, 106 via the heat exchanger package 108. This allows the fan to forcefully remove debris accumulated on or in the perforations 107.
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.
