Variable displacement swash-plate type compressor

Claim 2

A variable displacement swash-plate type compressor comprising: a cylinder block having a plurality of cylinder bores therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to be reciprocally moved in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of an associ­ated cylinder bore; a support portion disposed coaxially with said shaft and supporting a central portion of said swash plate rotatably and tiltably; and a spool for driving said support portion axially of said shaft to move said central portion of said swash plate axially of said shaft to change the angle of tilt of said swash plate, whereby the strokes of reciprocatory movements of said pistons in said cylinder bores are changed in such a manner that, in each working chamber on one side of each piston, the piston can always stroke to a predetermined position regardless of the change in the angle of tilt of said swash plate.

Claim 3

A variable displacement swash-plate type com­pressor according to Claim 1, wherein said support por­tion has a spherical support surface which rotatably and slidably engages with a spherical surface portion formed on said central portion of said swash plate.

Claim 4

A variable displacement swash-plate type com­pressor according to Claim 1, wherein said shaft extends through said swash plate and said spool is slidably mounted on said shaft.

Claim 5

A variable displacement swash-plate type com­pressor according to Claim 1, wherein said shaft is disposed only on one side of said swash plate.

Claim 6

A variable displacement swash-plate type com­pressor according to Claim 1, wherein said shaft is provided with a flat web portion while said swash plate has a slit in which said flat web portion is received, whereby said swash plate is tiltably connected to said shaft through the engagement between said flat web por­tion and said slit.

Claim 7

A variable displacement swash-plate type com­pressor according to Claim 5, wherein said flat web por­tion has a slit while portions of said swash plate defin­ing said slit have pin-receiving holes, whereby said swash plate is tiltably connected to said shaft by means of a pin extending through said slot and receive in said pin-receiving holes.

Claim 8

A variable displacement swash-plate type com­pressor according to Claim 5, wherein said flat web portion has a pin-receiving hole while portions of said swash plate defining said slit have slots, whereby said swash plate is tiltably connected to said shaft by means of a pin extending through said slots and received in said pin-receiving hole.

Claim 9

A variable displacement swash-plate type com­pressor according to Claim 7, wherein said pin is rotat­ably held in said pin-receiving hole through the inter­mediary of a bearing.

Claim 10

A variable displacement swash-plate type com­pressor according to Claim 1, wherein, when the strokes of reciprocatory movements of said pistons in said cylinder bores are changed by a change in the angle of tilt of said swash plate, the top dead center of each piston is so positioned in the working chamber on one side of the piston that no dead volume is formed in said working chamber regardless of the change in the angle of tilt of said swash plate.

Claim 11

A variable displacement swash-plate type com­pressor comprising: a cylinder block having at least one cylinder bore therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to reciprocatorily stroke in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of an associated cylinder bore; a support portion disposed coaxially with said shaft and supporting a central portion of said swash plate rotatably and tiltably; a spool for driving said support portion axially of said shaft; a control pressure chamber provided on a side of said spool opposite to said support portion such that said spool is moved axially of said shaft in accord­ance with an internal pressure of said control pressure chamber; and a control valve adapted for introducing selec­tively either one of the suction pressure of said compres­sor and the discharge pressure of said compressor into said control pressure chamber; the arrangement being such that, when the dis­charge pressure is introduced into said control pressure chamber by said control valve, the internal pressure of said control pressure chamber produces a force which causes said spool to move said support portion in the direction to increase the angle of tilt of said swash plate, such that, when said suction pressure is intro­duced into said control pressure chamber by said control valve, said support portion and said spool are moved in the direction to decrease the angle of tilt of said swash plate by the compression reactional force acting on said pistons, and such that, in each working chamber on one side of each piston, the piston can always stroke to a predetermined position regardless of the change in the angle of tilt of said swash plate.

Claim 12

A variable displacement swash-plate type com­pressor comprising: a cylinder block having at least one cylinder bore therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to reciprocatorily stroke in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of an associated cylinder bore; a support portion disposed coaxially with said shaft and supporting a central portion of said swash plate rotatably and tiltably; a spool for driving said support portion axially of said shaft; a control pressure chamber provided on a side of said spool opposite to said support portion such that said spool is moved axially of said shaft in accord­ance with an internal pressure of said control pressure chamber; and a control valve adapted for introducing selec­tively either one of the suction pressure of said compres­sor and the discharge pressure of said compressor into said control pressure chamber; the arrangement being such that, when the dis­charge pressure is introduced into said control pressure chamber by said control valve, the internal pressure of said control pressure chamber produces a force which causes said spool to move said support portion in the direction to increase the angle of tilt of said swash plate, such that, when said suction pressure is intro­duced into said control pressure chamber by said control valve, said support portion and said spool are moved in the direction to decrease the angle of tilt of said swash plate by the compression reactional force acting on said pistons, and such that, in each working chamber on one side of each piston, the piston can always stroke to a predetermined position regardless of the change in the angle of tilt of said swash plate.

Claim 13

A variable displacement swash-plate type com­pressor according to Claim 10, wherein a plurality of such cylinder bores are formed in said cylinder block and extend in parallel with one another.

Claim 14

A variable displacement swash-plate type compressor according to Claim 10, wherein said control valve includes a control pressure passage communicating with said control pressure chamber, a high pressure intro­duction passage for introducing pressure available at the discharge side of said compressor, a low pressure intro­duction passage for introducing pressure available at the suction side of said compressor and a change-over valve for selectively bringing either one of said high and low pressure introduction passages into communication with said control pressure passage.

Claim 15

A variable displacement swash-plate type com­pressor according to Claim 10, wherein said control pressure chamber is communicated with the discharge side of said compressor through a flow resistance means, and wherein said control valve includes a control pressure passage communicating with said control pressure chamber, a low pressure introduction passage for introducing pressure available at the suction side of said compres­sor, and a valve member for selectively connecting and disconnecting said low pressure introduction passage to and from said control pressure chamber.

Claim 16

A variable displacement swash-plate type com­pressor comprising: a cylinder block having cylinder bores therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to reciprocatorily stroke in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of said cylinder bores; a support portion disposed coaxially with said shaft and adapted to support a central portion of said swash plate rotatably and oscillatably; a spool for driving said support portion axially of said shaft; control means for driving said spool axially of said shaft between a maximum displacement position in which the angle of tilt of said spool is maximized and a minimum displacement position in which the angle of tilt of said swash plate is minimized; and auxiliary loading means operative when said control means has driven said spool more than a predeter­mined distance from said minimum displacement position to apply to said spool a load which acts to suppress the movement of said spool towards said maximum displacement position more than said predetermined distance from said minimum displacement position; the movement of said spool displacing said central portion of said swash plate axially of said shaft and changing the angle of tilt of said swash plate.

Claim 17

A variable displacement swash-plate type com­pressor comprising: a cylinder block having cylinder bores therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to reciprocatorily stroke in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of said cylinder bores; a support portion disposed coaxially with said shaft and adapted to support a central portion of said swash plate rotatably and oscillatably; a spool for driving said support portion axially of said shaft; control means for driving said spool axially of said shaft between a maximum displacement position in which the angle of tilt of said spool is maximized and a minimum displacement position in which the angle of tilt of said swash plate is minimized; and auxiliary loading means operative when said control means has driven said spool more than a predeter­mined distance from said minimum displacement position to apply to said spool a load which acts to suppress the movement of said spool towards said maximum displacement position more than said predetermined distance from said minimum displacement position; the movement of said spool displacing said central portion of said swash plate axially of said shaft and changing the angle of tilt of said swash plate.

Claim 18

A variable displacement swash-plate type com­pressor according to Claim 14, wherein said auxiliary loading means comprise a spring means.

Claim 19

A variable displacement swash-plate type com­pressor according to Claim 15, wherein said spring means is disposed between said spool and one end of said shaft in such a manner that the compression of said spring means is commenced when said spool has traveled in excess of said predetermined distance.

Claim 20

A variable displacement swash-plate type com­pressor according to Claim 15, wherein said spring means is disposed between said spool and said cylinder block in such a manner that the loading by said spring means is commenced when said spool has traveled in excess of said predetermined distance.

Claim 21

A variable displacement swash-plate type com­pressor according to Claim 15, further including an end plate attached to an end of said cylinder block and covering said working chambers, and wherein said spring means is disposed between said spool and said end plate in such a manner that said spring means becomes effec­tive to produce a resilient load when said spool has traveled in excess of said predetermined distance.

Claim 22

A variable displacement swash-plate type com­pressor according to Claim 15, wherein said spring means is disposed between said support portion and a retainer portion provided on said shaft so as to oppose said support portion, said spring means becoming effective to produce a resilient load when said support portion has traveled in excess of said predetermined distance.

Claim 23

A variable displacement swash-plate type com­pressor comprising: a cylinder block having cylinder bores therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to reciprocatorily stroke in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of said cylinder bores; a support portion disposed coaxially with said shaft and adapted to support a central portoin of said swash plate rotatably and oscillatably; a spool for driving said support portion axially of said shaft; control means for driving said spool axially of said shaft to move said central portion of said swash plate axially of said shaft while changing the angle of tilt of said swash plate, thereby causing the strokes of reciprocatory movements of said pistons in said cylinder bores to vary in such a manner that the position of the stroke end of each piston in a first working chamber on one end thereof is different from the position of the stroke end of said piston in a second working chamber on the other end of said piston; and auxiliary biasing means for applying a biasing force acting in a direction from said first working cham­ber towards said second working chamber so as to produce a torque which acts in the direction to reduce the angle of tilt of said swash plate.

Claim 24

A variable displacement swash-plate type com­pressor comprising: a cylinder block having cylinder bores therein; a shaft rotatably supported in said cylinder block; a swash plate tiltably connected to said shaft and adapted to be rotated together with said shaft; pistons slidably received in said cylinder bores and adapted to reciprocatorily stroke in said cylinder bores in accordance with an oscillatory motion of said swash plate; working chambers formed between both ends of each of said pistons and adjacent surfaces of said cylinder bores; a support portion disposed coaxially with said shaft and adapted to support a central portoin of said swash plate rotatably and oscillatably; a spool for driving said support portion axially of said shaft; control means for driving said spool axially of said shaft to move said central portion of said swash plate axially of said shaft while changing the angle of tilt of said swash plate, thereby causing the strokes of reciprocatory movements of said pistons in said cylinder bores to vary in such a manner that the position of the stroke end of each piston in a first working chamber on one end thereof is different from the position of the stroke end of said piston in a second working chamber on the other end of said piston; and auxiliary biasing means for applying a biasing force acting in a direction from said first working cham­ber towards said second working chamber so as to produce a torque which acts in the direction to reduce the angle of tilt of said swash plate.

Claim 25

A variable displacement swash-plate type com­pressor according to Claim 20, wherein said auxiliary biasing means comprises a spring which applies a load to said spool in a direction to reduce the amount of move­ment of said spool towards said support portion.

Claim 26

A variable displacement swash-plate type com­pressor according to Claim 21, wherein said spring is disposed to contact at its ends with said spool and with said shaft.

Claim 27

A variable displacement swash-plate type compressor according to Claim 20, wherein said auxiliary biasing means comprises a boosting passage means which introduces the discharge pressure of said compressor into said first working chamber.

Claim 28

A variable displacement swash-plate type com­pressor according to Claim 23, wherein said auxiliary biasing means comprises a communication means which pro­vides communication between said first working chamber and a discharge chamber, said discharge chamber commu­nicating with said second chamber through a discharge port and a discharge valve.

Claim 29

A variable displacement swash-plate type com­pressor according to Claim 24, further including a side plate provided on one end surface of said cylinder block, said side plate having said first working chamber and said discharge port through which said second working chamber communicates with said discharge chamber, said communicating means being provided in said side plate.

Claim 30

A variable displacement swash-plate type com­pressor according to Claim 24, wherein said communicating means comprises a relief port formed in said discharge valve.

Claim 31

A variable displacement swash-plate type com­pressor according to Claim 20, wherein said auxiliary biasing means comprises a dead volume generating means for changing the position of stroke end of said piston in said second working chamber and establishing a dead volume on the end of said piston in said second working chamber.

Claim 32

A variable displacement swash-plate type com­pressor according to Claim 27, further comprising: a flat web portion formed on said shaft; a slit provided on said swash plate and receiving said web portion; a slot formed in said flat web portion; pin-receiving holes formed in portions of said swash plate which define said slit; and a pin extending through said slot and received in said pin-receiving holes so as to tiltably connect said swash plate to said shaft; said slot being so designed that, when the angle of tilt of said swash plate is decreased as a result of movement of said spool, a dead volume is formed in said second working chamber.