Variable capacity swash plate type refrigerant compressor having a double fulcrum hinge mechanism

Abstract

A variable capacity single headed piston swash plate type refrigerant compressor is provided with a double fulcrum hinge mechanism having a pair of hinges for providing a pivotal connection between a rotary support element of a drive shaft and a swash plate assembly, causing reciprocation of a plurality of single headed pistons in cylinder bores for compressing a refrigerant gas. The pair of hinges of the double fulcrum hinge mechanism cooperate to absorb reaction forces of the compression and suction of the refrigerant gas acting from the pistons on the swash plate assembly to thereby prevent application of a local load to a sleeve element on which the swash plate assembly is turnably mounted.

Description

TECHNICAL FIELD

The present invention relates to a variable capacity swash plate type refrigerant compressor mainly used for an airconditioner for a car. More particularly, it relates to a variable capacity single headed piston swash plate type compressor provided with a double fulcrum hinge mechanism able to pivotally support a variable inclination swash plate assembly while preventing an application of an excessive load to a sleeve element on which the variable inclination swash plate assembly is turnably mounted.

BACKGROUND ART

Japanese Unexamined (Kokai) Utility Model Publication No. 62-183082, published on Nov. 20, 1987 by the Japanese Patent Office, discloses a variable capacity swash plate type compressor having single headed pistons therein. The variable capacity swash plate type compressor of Japanese Unexamined Utility Model Publication '082 includes a cylinder block having a crank chamber formed therein for housing an inclination changeable wobble plate assembly, and a plurality of cylinder bores in which a plurality of single headed pistons are reciprocally fitted, to suck and compress a refrigerant gas and to discharge the compressed refrigerant gas. The wobble plate assembly includes a rotary drive element rotatable with the drive shaft and a swash plate non-rotatably supported on the rotary drive element, and is driven by a rotatably supported axial drive shaft to which a lug member is fixedly attached to be projected radially and rotated together with the drive shaft within the crank chamber. The lug member is operatively connected to the rotary drive element of the wobble plate assembly via a hinge mechanism, and a sleeve element slidably mounted on the drive shaft is also operatively connected to the rotary drive element of the wobble plate assembly. Namely, the rotary drive element is able to be rotated together with the drive shaft and to change an angle of inclination thereof from an erect position corresponding to a small compression capacity position to a fully inclined position corresponding to a large compression capacity position. The hinge mechanism includes an elongated guide hole bored through the lug member, and a hinge pin having one end movably fitted in the elongated guide hole of the lug member and the other end fixed to a swing plate member extended from the rotary drive plate. The sleeve element is arranged to be axially slid, and provided with a lateral pin radially projected therefrom to form trunnion pins about which the rotary drive plate is pivotally mounted. The swash plate of the wobble plate assembly is operatively connected to the plurality of pistons via respective piston rods having ball-and-socket joints on both ends, and thus, when the drive shaft is rotated, the rotation of the drive shaft and the rotary drive element is converted into a reciprocation of the respective pistons in the cylinder bores. The cylinder block has a communication passageway formed therein and extended between the crank chamber and a suction chamber, for receiving therein the refrigerant gas before compression and an extent of the communication between the abovementioned two chambers is controlled by a capacity control valve.

With the above-mentioned compressor, when the respective pistons are reciprocated in response to the rotation of the drive shaft, the refrigerant gas before compression is pumped from the suction chamber into the cylinder bores, to be compressed by the pistons during the suction and compression strokes of the pistons, and the compressed gas is discharged from the cylinder bores toward a discharge chamber for the refrigerant gas after compression. During the operation of the compressor, a force consisting of first and second forces acts on the wobble plate assembly from the pistons, as a reaction of the compression and suction of the refrigerant gas by the pistons, and the wobble plate assembly is physically supported by the hinge mechanism at a fulcrum position thereof at which the hinge pin is in contact with the guide wall of the elongated guide hole of the lug member.

The construction of the above-mentioned hinge mechanism including the projected lug member radially projected from the drive shaft and the hinge pin in engagement with the elongated hole of the lug member results in an arrangement such that the fulcrum position of the hinge mechanism is moved around the axis of the drive shaft so as to constantly correspond to a given position of the swash plate at which the swash plate is connected to one of the pistons moved in the cylinder bore to the top dead center "T" thereof from the bottom dead center ,assembly increasing the operational life of the compressor.

Claims

1. A variable capacity single headed piston swash plate type compressor comprising:

an axially extended cylinder block having front and rear ends thereof and a plurality of axial cylinder bores formed therein;

a front housing sealingly connected to the front end of said cylinder block and defining a closed crank chamber therein extending in front of ends of the cylinder bores;

a rear housing connected to the rear end of said cylinder block and defining therein a suction chamber for a refrigerant gas before compression and a discharge chamber for the refrigerant gas after compression;

a drive shaft rotatably held by said cylinder block and said front housing with a longitudinal axis thereof extending through said crank chamber;

a rotary support element mounted on said drive shaft to be rotated therewith in said crank chamber;

a variable inclination rotary swash plate assembly pivotally held by a hinge means and slidably mounted on said drive shaft via a slidable sleeve element for rotation about an axis perpendicular to the axis of said drive shaft to thereby vary an angle of inclination thereof;

a plurality of reciprocatory single headed pistons fitted in said cylinder bores or said cylinder block and engaged with said swash plate assembly via a motion conversion means for converting rotation of said swash plate assembly into reciprocation of said single headed pistons in said cylinder bores; and

a control valve means for adjusting a fluid pressure in said crank chamber to thereby control the capacity of said compressor,

said hinge means being provided with a pair of hinges separately coupled to said swash plate assembly to provide two fulcrum positions about which said swash plate assembly is pivotally hinged, said two fulcrum positions being spaced apart from one another with respect to a center position which lies in a plane including the axis of said drive shaft and passing through a predetermined position of said swash plate assembly at which said swash plate assembly is engaged with one of said plurality of pistons brought to a top dead center thereof.

2. A variable capacity single headed piston swash plate type compressor according to claim 1, wherein said two fulcrum positions of said pair of hinges of said hinge means are symmetrically arranged on opposite sides of said plane, one of said two fulcrum positions absorbing a reaction force of the compression of said refrigerant gas acting from said pistons on said swash plate assembly while the other of said two fulcrum positions absorbs a reaction force of the suction of said refrigerant gas acting from said pistons on said swash plate assembly, .

3. A variable capacity single headed piston swash plate type compressor according to claim 1, wherein said pair of hinges of said hinge means comprises:

a pair of support arms extended toward said swash plate assembly from said rotary support element;

a pair of guide pins arranged in parallel with each other, and slidably pivoted on said pair of support arms, said pair of guide pins being arranged to be symmetrical with respect to said plane.

4. A variable capacity single headed piston swash plate type compressor according to claim 3, wherein said pair of guide pins of said pair of hinges of said hinge means are pivotally supported on said pair of support arms via turnable ball elements received in spherical race elements, said pair of guide pins passing through said turnable ball elements.

5. A variable capacity single headed piston swash plate type compressor according to claim 1, wherein said pair of hinges of said hinge means comprises:

a pair of support arms extended toward said swash plate assembly from said rotary support element;

a pair of guide pins arranged to be coaxial with each other, and slidably fitted in said pair of support arms, said pair of guide pins being arranged to be symmetrical with respect to said plane.

6. A variable capacity single headed piston swash plate type compressor according to claim 5, wherein said pair of guide pins of said pair of hinges of said hinge means are pivotally and slidably fitted in a pair of elongated through-bores formed in said pair of support arms.

7. A variable capacity single headed piston swash plate type compressor according to claim 1, wherein said variable inclination rotary swash plate assembly is slidable on said drive shaft via a slidable sleeve element has having a spherical outer face thereof on which said swash plate assembly is turnably and slidably mounted.