Air conditioning compressor

• US 3,998,570 A
• Filed: 04/23/1975
• Issued: 12/21/1976
• Est. Priority Date: 04/23/1975
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Jacobs, James W.
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US05/570,615
• Time in Patent Office: 608 Days
• Field of Search: 62/228, 62/196, 417/274, 92/60.5
• US Class Current: 417/274
• CPC Class Codes: F04B 27/0878 Pistons
• CPC Class Codes: F04B 27/16 of pumps with stationary cylinders
• CPC Class Codes: F04B 39/0005 adaptations of pistons
• CPC Class Codes: F04B 49/16 by adjusting the capacity of dead spaces of working chambers

Abstract

A piston type compressor for use in an automotive air conditioning system with variable pumping or compressing capacity which is automatically modulated in response to operating conditions. Compressor improvements are solely to the piston so that the present investment in fixed displacement compressors is not diminished. Previous compressors may be modified by the substitution of the improved pistons to create a variable capacity compressor. Specifically, the piston modifications include a pressure responsive displacement means on the piston end which extends into the compression chamber during portions of the intake stroke and compression stroke to effectively decrease the volumetric pumping capacity of the compressor whenever a predetermined low pressure is sensed.

Claims

1. A piston type compressor for use in an automotive air conditioning system comprising:

a housing having at least one cylinder bore therein and including an end portion overlying the cylinder bore;

a first piston supported for reciprocal movement within said cylinder bore and forming in conjunction with said cylinder bore and said end portion a variable volume compression chamber for compressing refrigerant therein;

said housing defining a valved inlet to said compression chamber and a valved outlet therefrom to control the flow of refrigerant into and from the compression chamber during an intake stroke and a compression stroke respectively;

said first piston having a recess formed therein adjacent said compression chamber;

a second piston supported for reciprocal movement in said recess and movable with respect to said first piston so as to extend into said compression chamber and to displace refrigerant therefrom;

an axially extendible and contractible bellows located between said pistons and forming a sealed enclosure filled with a compressible fluid whereby movement of said bellows controls the extension and contraction of said second piston and exerts a force on said second position tending to cause it to extend into said compression chamber when the pressure force acting on said second piston from refrigerant within said compression chamber is less than the internal force on said bellows exerted by said fluid.

2. A piston type compressor for use in an automotive air conditioning system comprising:

a housing having at least one cylinder bore therein and including an end portion overlying the cylinder bore;

a first piston supported for reciprocal movement within said cylinder bore and forming in conjunction with said cylinder bore and said end portion a variable volume compression chamber for compressing refrigerant therein;

said housing defining a valved inlet to said compression chamber and a valved outlet therefrom to control the flow of refrigerant into and from the compression chamber during an intake and a compression stroke respectively;

said first piston having a recess formed therein adjacent said compression chamber;

a second piston of generally cup-shaped configuration having an annular side wall slideably engaging the wall portions of said piston which form said recess so as to permit said second piston to reciprocate within the recess and thereby move a face portion into and out of said compression chamber whereby refrigerant in said compression chamber is displaced by said second piston;

an axially extendible and contractible bellows located between said pistons and forming a sealed enclosure filled with a compressible fluid whereby axial extension and contraction of said bellows is caused by changes in refrigerant pressure in the compression chamber which produces a force on said second piston and bellows which tends to move the second piston further into said recess when the force produced by the pressure within the compression chamber is greater than the internal pressure force on the bellows exerted by said compressible fluid and which tends to move the second piston away from said first piston and into said compression chamber when the force produced by the pressure within the compression chamber is less than the internal force on the bellows exerted by said compressible fluid outward from said first piston into said compression chamber during a portion of the intake and compression stroke whereby the displacement of the second piston in an outward position effectively decreases the displacement of the compressor defined by movement of said first piston and the pumping capacity of the compressor.