Air Cleaner For Crankcase Ventilation System

Abstract

An air cleaner for a closed positive crankcase ventilation system includes an air filter having a pleated filter element which has an enlarged pleat outwardly surrounding the air intake for the ventilation system and a cylindrical filter element disposed inwardly of the pleats and defining with the enlarged pleat a filtering chamber in which the air flowing through the ventilation system to the crankcase during normal engine operating conditions is filtered by the enlarged pleat and the excess blowby gases and crankcase vapors flowing from the crankcase to engine carburetor during high-speed operation of the engine are filtered by the cylindrical filter element.

Description

Recently, legislation has been enacted requiring internal combustion engines of motor vehicles to be equipped with a closed positive crankcase ventilation system. Basically, this system incorporates two flow paths between the engine induction system and the engine crankcase. An outlet flow path fluidly connects the crankcase and the engine intake manifold and handles the removal of vapors and blowby gases which tend to collect in the crankcase by drawing them into the induction system with the vacuum normally formed by the operation of the engine. An intake flow path fluidly connects the air cleaner and the crankcase and functions to admit fresh air to the ventilation system. Under normal operating conditions, the outlet flow path can adequately handle the vapors and blowby gases present in the crankcase without upsetting the air-fuel ratio to the engine. However, under rapid acceleration or high-speed operating conditions, the intake manifold vacuum is insufficient to completely vent the blowby gases in the crankcase and the excess volume reversely flows through the intake flow path to the air cleaner.

In the past, two basic methods, "clean side" and "dirty side" filtration, have been used in the closed positive crankcase ventilation systems. The "dirty side" filtration system has an inlet for the intake flow path which is upstream or exterior of the air cleaner filter. With this method, the reverse flow of crankcase vapors and blowby gases under high-speed operating conditions is filtered prior to entering the induction system thereby eliminating the problem of carburetor clogging and malfunctioning caused by deposited contaminants. However, without a supplemental filter, the flow of "road" dust and other contaminants into the crankcase is not controlled. The "clean side" filtration method positions the inlet for the intake flow path internal or downstream of the air filter. While this method does not filter the flow of crankcase vapors and blowby gases to the carburetor, it does limit the amount of "road" dust and contaminants delivered to the crankcase.

The present invention contemplates providing a closed positive crankcase ventilation system for positively filtering the flow of vapors between the air cleaner and the crankcase under all operating conditions while, at the same time, providing a system compatible with current filter and air cleaner constructions. In the accomplishment of this objective, the air cleaner filter includes an accordion-pleated filtering element having a single enlarged pleat which radially outwardly encircles the inlet of the intake flow path. A cylindrical filtering element is disposed inwardly of the pleats and defines with the enlarged pleat a sealed filtering chamber which is fluidly connected to the crankcase. Under normal engine operating conditions, air flowing inwardly to the chamber is filtered by the enlarged pleat before entering the crankcase and the induction system. Under engine operating conditions of high-speed or sudden acceleration, the excess blowby gases reversely flowing through the intake flow path are filtered by the cylindrical filter element before entering the induction system. Thus, the air entering the carburetor in the present closed positive crankcase ventilation system is positively filtered for all modes of engine operation thereby combining the advantages of both "clean side" and "dirty side" crankcase filtration.

Accordingly, it is an object of the present invention to provide an air cleaner for a closed positive crankcase ventilation system of an internal combustion engine wherein both "clean side" and "dirty side" crankcase filtration are achieved by a novel modification of the air filter.

Another object of the present invention is to provide an air filter for an air cleaner used in a closed positive crankcase ventilation system wherein the filter includes an enlarged pleat which partially surrounds the air intake to the ventilation system and serves to filter air entering the crankcase under normal engine operating conditions, the filter further including an inner filtering element disposed across the enlarged pleat which serves to filter excess blowby gases flowing from the crankcase to the engine induction system during high-speed operation.

Another object of the present invention is to provide an air cleaner for a closed positive crankcase ventilation system wherein an accordion-pleated filter element includes a single enlarged pleat which outwardly surrounds the air intake for the ventilation system for filtering air flowing to the crankcase during normal engine operating conditions thereby providing "clean side" crankcase filtration and a cylindrical filter element disposed across the enlarged pleat for filtering excess blowby gases from the crankcase to the engine induction system during high-speed engine operation thereby providing "dirty side" crankcase filtration.

These and other objects will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings in which:

FIG. 1 is a partially sectioned elevational view of an internal combustion engine having a closed positive crankcase ventilation system which incorporates an air cleaner made in accordance with the present invention;

FIG. 2 is an enlarged view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 2; and

FIG. 4 is a view taken along line 4-4 of FIG. 3.

Referring to FIG. 1, an internal combustion engine 10 includes a crankcase 12 and an induction system 14 comprising an air cleaner 16, a carburetor 18, and an intake manifold 20. A pair of rocker arm covers 22 and 24 are fastened atop engine cylinder banks 26 and 28, respectively, and define rocker chambers 30 and 32. An intake pipe 34 fluidly connects the rocker chamber 32 with the interior of the air cleaner 16 and an outlet pipe 35 fluidly connects the rocker chamber 30 with the intake manifold 20. The outlet pipe 35 is provided with a positive crankcase ventilation valve 36 of the type shown and described in Pittsley U.S. Pat. No. 3,359,960, assigned to the assignee of the present invention, wherein the valve serves to regulate the flow of blowby gases from the crankcase 12 so as not to upset the air-fuel ratio of the engine under low-load conditions. The pipes 34 and 35 form the flow paths for a closed positive crankcase ventilation system wherein a portion of the air entering the air cleaner 16 passes through the pipe 34 to the rocker chamber 32 and into the crankcase 12 through various passageways within the interior of the engine 10. This air mixes with vapors in the crankcase and blowby gases which are blown past the engine pistons into the crankcases. Thereafter, these gases flow outwardly through internal engine passageways and the rocker chamber 30 to the intake manifold 20 via the outlet pipe 35.

Referring to FIG 2, the air cleaner 16 includes a housing formed by an upper member 37 and a lower member 38. The lower member 38 includes a central opening forming an air outlet 39 defined by a rim 40 which is disposed in a counterbore formed in the upper end of the air inlet horn 42 of the carburetor 18. The lower member 38 further includes an upwardly opening peripheral channel 44 in which a resilient gasket 46 is disposed. The upper member 37 includes a circular lid 48 having a downwardly depending circular sidewall 50 that terminates in an annular rim 52 which sealingly engages the gasket 46. A bolt 54 is secured at a lower end to the inlet horn 42 and has a threaded upper end which extends through a central aperture in the lid 48. A wing nut 56 is threaded on the bolt and, when tightened, serves to hold the upper member 37 and the lower member 38 securely against the air horn 42. An air inlet tube or snorkel 58 is secured around a port 60 formed in the sidewall 50 to form an air inlet passage to an air distribution and acoustical capacitance chamber 61 for the air induction system 14.

An air filter 62 for filtering the air entering the induction system 14 is disposed interior of the housing. The filter 62 includes plastisol end caps 64 and 66 which are sealingly retained in annular seats 67 and 68 formed in the upper housing member 37 and the lower housing member 38. As shown in FIGS. 3 and 4, the filter 62 includes a first filter element 70 formed of an oiled paper construction and comprising a circumferentially spaced series of pleats 71. A second cylindrical filter element 72 formed of a resin-treated paper is disposed interiorly across the inwardly facing tips 74 of the first filter element 70. The ends of the filtering elements 70 and 72 are formed or otherwise embedded in the end caps 64 and 66 to form the illustrated unitized filter. As shown in FIGS. 3 and 4, the filter element 70 includes a single enlarged generally U-shaped pleat 76 which, in cooperation with the second filtering element 72, forms a sealed filtering chamber 78. The intake pipe 34 extends through the lower member 38 into the interior of the air cleaner 16 with an upper end 80 extending into and registering with the filtering chamber 78 through an aperture 82 formed in the end cap 66.

Under normal engine operating conditions, the air flows inwardly through the snorkel 58 and is filtered by the first filter element 70 and the second filter element 72 before entering the carburetor 18 and induction system 14. A portion of the entering air is filtered by the enlarged pleat 76 before passing downwardly through the rocker chamber 30 to the crankcase 12. This air mixes with the crankcase vapors and blowby gases and the resultant mixture is routed to the intake manifold 20 via the outlet pipe 35. Under high-speed operation or sudden acceleration of the engine, an excessive amount of blowby gases flow past the cylinders to the crankcase 12. In certain instances, the volume of gases cannot be handled by outlet pipe 35 and a portion reversely flows through intake pipe 34 into the filtering chamber 78 where they are filtered by the second filter element 72 prior to entering the engine induction system 14. Thus, under all modes of engine operation, the flow of air to the carburetor 18 and the crankcase 12 is filtered thereby avoiding the intake and accumulation of contaminants and, in this manner, provide both "dirty side" and "clean side" crankcase filtration by the unique air cleaner and filter construction described above.

Although only one form of this invention has been shown and described, other forms will be readily apparent to those skilled in the art. Therefore, it is not intended to limit the scope of this invention by the embodiment selected for the purpose of this disclosure but only by the claims which follow.

Claims

What we claim is:

1. An air cleaner adapted for use in a closed positive crankcase ventilation system on an internal combustion engine induction system wherein the air cleaner comprises: a housing formed by an upper member and a lower member, said housing having an air inlet and an air outlet spaced therefrom and adapted to register with the induction system of said engine; an air filter positioned between the air inlet and air outlet having spaced annular end caps disposed interior of said housing with said end caps sealingly engaging said upper member and said lower member, said filter including a first annular accordion-pleated filter element bonded to said end caps having one enlarged pleat, and a second cylindrical filter element disposed within said first-mentioned filter element and in abutment therewith and bonded to said annular end caps to make up a unitized filter and form a filtering chamber with said one pleat, an aperture formed in said housing and in one of said end caps with said aperture being within said one enlarged pleat and in registration with said filtering chamber.

2. An air cleaner adapted for use in a closed positive crankcase ventilation system on an internal combustion engine induction system wherein the air cleaner comprises: a housing formed by an upper member and a lower member, said housing having an air inlet and an air outlet spaced therefrom and adapted to register with the induction system of said engine; an air filter positioned between the air inlet and air outlet having spaced annular end caps disposed interior of said housing with said end caps sealingly engaging said upper member and said lower member, said filter including a first annular accordion-pleated filter element bonded to said end caps having one enlarged pleat, and a second cylindrical filter element disposed within said first-mentioned filter element and in abutment therewith and bonded to said annular end caps to make up a unitized filter and form a filtering chamber with said one pleat, an aperture formed in said lower member and in said one end cap engaging said lower member, with said aperture being within said one enlarged pleat and in registration with said filtering chamber; said one enlarged pleat being configured to conform to the shape of the aperture in said lower member and end cap.