Vapor guard system

• US 4,109,464 A
• Filed: 06/09/1977
• Issued: 08/29/1978
• Est. Priority Date: 06/09/1977
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Wickland, Warren A.
• Primary Examiner(s): Geoghegan, Edgar W.
• Application Number:
  US05/805,010
• Time in Patent Office: 446 Days
• Field of Search: 60/397, 60/411, 60/453, 91/369 B, 92/78, 92/79, 55/316, 55/327, 123/136, 123/119 F
• US Class Current: 60/397
• CPC Class Codes: B60T 13/52 indirect, i.e. vacuum booster units
• CPC Class Codes: B60T 17/002 Air treatment devices

Abstract

An activated charcoal filter is placed in the vacuum conduit between a brake booster and the point where the conduit is connected to an engine to tap intake vacuum for booster power. When for any reason fuel vapor from the engine tends to flow toward the brake booster the charcoal of the filter adsorbs the fuel vapor. When flow of air returns to the normal flow direction, from the booster to the engine, the fuel vapors are desorbed and returned to the engine. Thus the filter has a self-purging action. This effectively prevents condensed fuel vapor from adversely affecting elements of the booster such as the diaphragm when under some particular circumstances and in certain installations fuel vapor would otherwise be introduced into the booster and condensed.

Claims

1. In combination:

a vacuum suspended power brake booster having

a diaphragm dividing the booster into a vacuum chamber and

a variable pressure chamber into which atmospheric air is selectively admitted to operate the booster, said diaphragm having the characteristic that it may be deleteriously affected by condensed fuel vapor in contact therewith, said chambers being interconnected during brake booster release,

and means selectively interrupting the connection between said chamber when the booster is actuated;

an internal combustion engine having a fuel and air intake acting as a vacuum source when the engine is running and having fuel vapor therein;

a conduit fluidly connecting said intake and said vacuum chamber of said booster to provide vacuum thereto, said conduit including means normally retaining in said vacuum chamber the vacuum provided thereto by interrupting the fluid connection between said intake and said vacuum chamber when the absolute pressure in said intake is greater than the absolute pressure in said vacuum chamber but occasionally operating under certain conditions to reestablish such connection so that fuel vapor from said intake is drawn toward said brake booster by the lower absolute pressure in said vacuum chamber;

the improvement comprising a vapor guard system to prevent fuel vapor from said intake from reaching said diaphragm, said vapor guard system including an activated charcoal filter in said conduit connected on one side to said brake booster through said retaining means and on the other side to said intake so that all fluid flow in said conduit betwee said intake and said brake booster must pass through the activated charcoal of said filter, said activated charcoal acting to adsorb any fuel vapor tending to flow in said conduit from said intake toward said brake booster and acting to desorb the previously adsorbed fuel vapor with air flow through said conduit from the interconnected chambers of said brake booster to said intake, said filter thereby guarding said brake booster and the diaphragm therein against the presence of fuel vapor from said intake and periodically purging itself of any fuel vapor adsorbed therein.

2. A vapor guard system comprising:

a vacuum suspended power booster having one or more parts therein which may be adversely affected by concentrations of certain vapors including fuel vapors, and particularly condensed fuel vapors;

an internal combustion engine having a fuel and air intake acting as a vacuum source for said booster when the engine is running, said intake normally having fuel vapor therein;

a conduit fluidly connecting said intake and said booster to provide vacuum thereto, said conduit also being capable under certain conditions of conducting fuel vapor from said intake toward said booster;

and a filter in said conduit connected only to said booster on one side and said intake on the other side so that all fluid flow in said conduit between said intake and said booster must pass through said filter, said filter having therein a material which acts to adsorb fuel vapor tending to flow in said conduit from said intake when fluid flow in said conduit occurs toward said booster and acting to purge itself by desorbing the previously adsorbed fuel vapor with air flow through said conduit from said booster to said intake so that the fuel vapor so desorbed is returned to said intake, said filter thereby guarding said booster and particularly said parts therein against the adverse presence of fuel vapor from said intake and periodically purging itself of fuel vapor adsorbed therein.

3. In a power servomotor system having a servomotor operated by differential air pressures with one pressure being atmospheric air and the other pressure being air at other than atmospheric air and generated by a pressure source which also entrains vapors therein which are capable of adversely affecting said servomotor if the vapors enter said servomotor and particularly if the vapors are condensed therein, said servomotor being connected to said pressure source by a fluid conduit, the improvement comprising a vapor trap in said conduit which traps and holds said entrained vapors in other pressure otherpressure air which would otherwise be transmitted to said servomotor from said pressure source during air flow from said pressure source to said servomotor through said fluid conduit, said vapor trap being purged of vapors so trapped therein upon air flow through said fluid conduit from said servomotor to said pressure source.