Under-hood engine air intake system

An engine air intake system includes an engine air intake device and a plenum cooling compartment that is separate from the engine compartment by a baffle. A fan draws outside ambient air into the plenum cooling compartment and out of the plenum cooling area via a heat exchanger. The cooling compartment is designed such that a distance between the heat exchanger and the baffle provides a gap from which the engine air intake device removes ambient air as a source for engine air. An option is provide for the system to withdraw outside ambient air from an area external to the plenum cooling compartment in high debris environments.

FIELD OF THE INVENTION

The invention relates to the structure and operation of air intake systems and to methods of supplying intake air to internal combustion engines. More specifically, it relates to a method, system and apparatus for supplying ambient or non-preheated air to an internal combustion engine for a work vehicle such as, for example, a mobile construction machine.

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

FIG. 1illustrates a work vehicle in which the invention may be used. The particular work vehicle illustrated inFIG. 1is an articulated four wheel drive loader1having a body10that includes a front body portion20pivotally connected to a rear body portion30by vertical pivots40, the loader being steered by pivoting of the front body portion20relative to the rear body portion30in a manner well known in the art. The rear body portion30includes an engine compartment50and a separately accessible plenum cooling compartment100. The front and rear body portions20and30are respectively supported on front drive wheels22and rear drive wheels32. An operator's station11is provided on the rear body portion30and is generally located above the vertical pivots40. The front and rear drive wheels22and32propel the vehicle along the ground and are powered in a manner well known in the art.FIG. 2shows a detailed oblique view of the rear body portion20illustrated inFIG. 1.

FIGS. 2,3and4are views of the plenum cooling compartment100and the separately accessible engine compartment50with the top door101, two side doors105,106and a fan door102of the plenum cooling compartment100illustrating an air intake system200including, a filter body210, a filter body clamp220, an air output tube230, a first output tube clamp240connecting the air output tube230to the filter body210, a second output tube clamp260connecting an outlet side231of the air output tube230to an engine55, and an air intake tube203routed through a wall or baffle104separating the plenum cooling compartment100from the engine compartment50. As illustrated inFIGS. 2,3and4, the top door101, the fan door102, two side doors105and106, the floor111and the baffle104form the plenum cooling compartment100. The two side doors105and106and the top door101contain perforations107for removing large debris from ambient air flowing into the plenum cooling compartment. The filter body clamp220is fixedly attached to the frame via the brace211and supports the filter body210.

As illustrated inFIG. 5, in this embodiment the at least one heat exchanger103includes five heat exchangers103a,103b,103c,103dand103eforming a heat exchanger package108located at a rear end of the vehicle and filling only a portion of the cooling compartment100. This arrangement creates a gap109between the baffle104, near which the air inlet203ais located, and the heat exchanger package108. A fan102aforms a part of the fan door102and serves to draw ambient air, via the perforations107in the hood101and the two side doors105,106into the plenum cooling compartment100, via the heat exchangers package108, and out of the plenum cooling compartment100, via the fan door102. As a result of this arrangement, non-preheated air flows in the gap109. Thus, the air intake system200supplies the ambient air flowing in the gap109to the engine55.

The plenum cooling compartment is designed such that the gap109between the heat exchanger package108and the baffle104is sufficiently large to reduce or minimize any air flow restrictions and the intake of preheated air. The size of the gap109varies with the size and design of the work vehicle.

The perforations107are sized to: (1) to block the entrance of airborne debris to the cooling compartment; and (2) to avoid frequent plugging of screens or perforations107. 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 compartment100to an above hood intake of air from an above-hood pre-cleaner250as shown inFIG. 4. This may be accomplished by: (1) removing the air intake tube203from the baffle104and covering the baffle inlet opening104awith a baffle inlet door104b; (2) loosening the filter body clamp220holding the filter body210in place; (3) loosening the air output tube clamp240fixedly holding the engine air output tube230to the filter body210; (4) removing an above-hood inlet door204on the engine compartment hood51; (5) rotating the filter body210to a position allowing the air inlet tube203to be routed through an opening204ain the engine compartment hood51provided by the removal of the above-hood inlet door204while allowing the engine air output tube230to remain connected to the engine and to rotate with respect to the filter body210; (6) connecting the air intake tube203to the above-hood pre-cleaner250; (7) tightening the body clamp220to fixedly hold the filter body210in place; (8) tightening the output tube clamp240to fixedly hold the engine air output tube230in place. The outlet side231of air output tube230remains fixedly connected to the engine55. Removal of the air intake tube203from the baffle104oh of the above hood inlet door204may be facilitated by loosening a tube clamp270. The tube clamp270may be, subsequently tightened once the air intake tube203is properly positioned.

In environments of extremely heavy debris a pressurization option is provided wherein the fan reverses periodically to withdraw air from outside the cooling compartment100via the fan door102and to force it through the perforations107in the hood101and the side doors105,106via the heat exchanger package108. This allows the fan to forcefully remove debris accumulated on or in the perforations107.

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.