Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Patent
1994-01-24
1997-12-02
Kamen, Noah P.
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
125 4112, 181204, 165135, F02B 7700
Patent
active
056924674
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a ventilation apparatus and more particularly to a ventilation apparatus for an enclosure lined with sound absorptive material.
BACKGROUND ART
The subject of noise pollution has become a critical issue in recent years and has had a very significant impact on the earthmoving industry. Rigid sound requirements for equipment have been adopted worldwide, resulting in extensive modifications to vehicles in an attempt to reduce the noise produced during their operation. Obviously, one of the primary sources of noise emanates from the engine of the vehicle. The most logical way to reduce the noise is to encase the engine in an enclosure that is lined with acoustical foam or other sound absorptive material. While this solution appears simple enough, one must remain aware of the cooling requirements for the engine and other powertrain components such as torque converters, hydraulic pumps, etc., whose heat exchangers are cooled by air passing through the engine's enclosure. It is not uncommon for the ventilation air moving through an engine enclosure of an earthmoving vehicle to pick up a heat load equivalent to approximately 20% of the output power. Therefore it is an absolute necessity to provide openings in the enclosure of sufficient size to not only reduce the temperature of the components within the enclosure but to also provide a flow of air through a radiator and various heat exchangers to cool fluid that is circulated internally through the engine and related components. This flow of air has conventionally been provided by an axial fan that is positioned behind the radiator and heat exchangers to draw ambient air from outside the enclosure through the enclosure and the fluid cooling devices. Arrangements of this type have been used successfully to attenuate a large portion of the noise that escapes from an engine enclosure. However, as the noise requirements have become more stringent, problems with this method of noise attenuation have been encountered. A logical solution to the more stringent requirement is to increase the amount of sound absorptive material within the enclosure and to reduce the number and/or size of openings in the enclosure through which noise may escape. When this happens, the flow of cooling air into the enclosure is reduced to a point of inadequacy. Not only is the flow of air that is passed by the fluid cooling devices reduced, but the flow of air through the enclosure itself is reduced which results in an overall increase in temperature within the compartment. This adversely affects many temperature sensitive components, such as the alternator, the fuel injection system and various electronic components such as microprocessors that have been incorporated into the operation of an engine through modern day engine technology. To increase the air flow, it has been common practice to provide a fan that will rotate at a greater speed. While this solution has achieved moderate success, we have reached a point where the fan speed requirements are so great that the noise created by the fan has surpassed the engine as the dominant noise source, particularly at high idle with an engine driven fan.
The next step in the evolution of the sound suppressed engine compartment resulted in the separation of the radiator and fluid cooling devices, including the fan, from the engine and its related components. One such design is typically disclosed in U.S. Pat. No. 3,866,580 issued to Whitehurst et al. on Feb. 18, 1975. This design provides a wall between the fluid cooling components and the engine related components. Ambient air outside the enclosure is drawn through openings in the side and top of the enclosure by an engine driven fan. The air flow passes through the fluid cooling components that are positioned on the engine side of the fan. The enclosure is ventilated by ambient air that is drawn from air inlets positioned at the rear and sides of the vehicle by a pressure differential created by the relationship between the engine exhaust pipe and the
REFERENCES:
patent: 4020900 (1977-05-01), Kitagawa
patent: 4086976 (1978-05-01), Holm et al.
patent: 4455971 (1984-06-01), Kirchweger et al.
patent: 4503931 (1985-03-01), Sugimoto et al.
patent: 4516657 (1985-05-01), Allard
Mikrut Daniel L.
Sahm William C.
Caterpillar Inc.
Kamen Noah P.
Perry William C.
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