SWASH-PLATE-TYPE COMPRESSOR

Abstract

A swash-plate-type compressor of a double-headed-piston configuration, wherein: a front intake chamber is formed set apart from a swash plate chamber so as to be positioned in a narrow space between circumferentially arranged front cylinder bores; and an intake-chamber-communication path is formed in a cylinder block, the intake-chamber-communication path allowing the front intake chamber and a shaft hole to communicate. A front-bore-communication path is formed on the cylinder block, the communication path allowing each of the plurality of front cylinder bores to communicate with the shaft hole. A front rotary valve is provided on a rotating shaft in which a lead-in groove is formed. The lead-in groove allows the intake-chamber communication path and the front-bore communication path to communicate in the stated order, while the lead-in groove rotates integrally with the rotating shaft. In the compact swash-plate-type compressor any decrease in pulsation or intake efficiency is minimized.

Description

TECHNICAL FIELD

The present invention relates to a swash plate compressor including a cylinder block having a shaft hole into which a rotary shaft is inserted, and a plurality of cylinder bores located around the shaft hole and arranged along a peripheral direction. The cylinder bores respectively receive pistons.

BACKGROUND ART

For example, Patent Document 1 describes a double-headed piston type swash plate compressor employing a double-headed piston. As shown in FIG. 11, a swash plate compressor 80 of Patent Document 1 includes a cylinder block 81 having three cylinder bores 81a. A double-headed piston 82 is accommodated in each cylinder bore 81a. The cylinder block 81 includes a single suction chamber 83, which is arranged between two adjacent cylinder bores 81a, and a single discharge chamber 84, which is arranged at a different location between two adjacent cylinder bores 81a. The suction chamber 83 and the discharge chamber 84 each having a necessary volume to suppress pulsation can be arranged in the cylinder block 81 by effectively using the region between adjacent cylinder bores 81a. This avoids enlargement of the swash plate compressor 80.

Although not shown in the drawing, in the swash plate compressor 80 of Patent Document 1, refrigerant is drawn from the suction chamber into the cylinder bores 81a when a reed type suction valve opens a suction port. When refrigerant is drawn through such a suction valve, the suction valve opens and closes in accordance with the difference in pressure between the interior of the corresponding cylinder bore 81a and the suction chamber. The suction valve does not open until the pressure in the cylinder bore 81a decreases to a predetermined pressure. Thus, the suction valve may not open at the desired timing. This may decrease the suction efficiency.

To prevent the suction efficiency from decreasing, the use of a rotary valve that mechanically communicates the suction chamber and cylinder bores is effective for the swash plate compressor 80 that avoids enlargement.

PRIOR ART DOCUMENTS

Patent Documents

Patent Document 1: Japanese Laid-Open Patent Publication No. H9-317633

Patent Document 2: Japanese Laid-Open Patent Publication No. 2007-138925

Patent Document 3: Japanese Laid-Open Patent Publication No. 2007-270790

SUMMARY OF THE INVENTION

Problems that are to be Solved by the Invention

As shown in FIG. 12, in a swash plate compressor 90 disclosed in Patent Document 2 that employs a rotary valve, refrigerant is first sent into an accommodation chamber 93a (suction chamber) in a front housing 93 through a communication groove 98 from a swash plate chamber 99. Thus, to guide the refrigerant to an suction passage 96, which is in communication with cylinder bores 97, the refrigerant in the front housing 93 (accommodation chamber 93a) is sent toward a cylinder block 91 though a supply passage 92a. More specifically, a rotation shaft 92 is must include the supply passage 92a, which extends from the front housing 93 to the cylinder block 91. This lengthens the supply passage 92a in the axial direction. Accordingly, in the swash plate compressor 90 of Patent Document 2, the formation of the supply passage 92a enlarges the swash plate compressor 90 in the axial direction.

As shown in FIG. 13, a swash plate compressor 100 of Patent Document 3 that also employs a rotary valve includes a rotation shaft 101 having a supplying passage 102 formed therein and a conducting hole 101a for communicating inside and outside of the supplying passage 102. A cylinder block 104 includes a suction recess 105 located around the rotation shaft 101. The conducting hole 101a communicates a swash plate chamber 106 with the supplying passage 102 through the suction recess 105.

In the Patent Document 3, when the suction recess 105 and the conducting hole 101a are in communication with the swash plate chamber 106, refrigerant in the swash plate chamber 106 flows in the supplying passage 102 through the suction recess 105 and the conducting hole 101a. The refrigerant further flows from the supplying passage 102 to cylinder bores 108 through a rotary valve 107. Also in Patent Document 3, the conducting hole 101a is formed in the rotation shaft 101 so that the rotation shaft 101 is elongated in the axial direction. The suction recess 105 is formed in the cylinder block 104 so that body of the swash plate type compressor 100 enlarges in the axial direction. The rotation shaft 101 having the supplying passage 102 needs to be enlarged in a radial direction to ensure the strength in the rotation shaft 101. This enlarges the body of the swash plate type compressor in the radial direction.

As discussed above, in the swash plate compressor 90 and 100, which employs conventional rotary valve, each of the swash plate chambers 99 and 106 functions as suction chamber. This complicates the structure of the rotary valve 107 and enlarges the rotary valve 107. This also enlarges the body of the swash plate compressor 90 and 100.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a small swash plate compressor, which suppresses pulsation and prevents the suction efficiency from decreasing.

Means for Solving the Problem

To achieve the foregoing object, one aspect of the present invention is a swash plate compressor including a cylinder block, a swash plate, pistons, a rotation shaft and a rotary valve. The cylinder block includes a shaft hole, cylinder bores, a swash plate chamber and a suction chamber. The shaft hole extends through the cylinder block. The cylinder bores are arranged along a circumferential direction around the shaft hole. The suction chamber is arranged in a space between the adjacent cylinder bores and is separated from the swash plate chamber. The swash plate is accommodated in the swash plate chamber. The pistons are connected with the swash plate and respectively arranged in the cylinder bores. The rotation shaft is arranged in the shaft hole and operative to rotate integrally with the swash plate. The rotary valve is provided with the rotation shaft to rotate integrally with the rotation shaft. The cylinder block includes a suction chamber communication passage that defines a communication path between the suction chamber and the shaft hole, and bore communication passages that define independent communication paths between the cylinder bores and the shaft hole. The rotary valve rotates integrally with the rotation shaft to provide sequential communication between the suction chamber communication passage and the bore communication passages.

Accordingly, the suction chamber and cylinder bores are arranged around the rotary valve along a circumferential direction. Thus, when the rotary valve is employed, body size of the rotary valve and the swash plate compressor are prevented from enlarged. In addition, since the rotary valve is employed, suction efficiency is prevented from being reduced as compared to when a suction valve is employed.

Preferably, the suction chamber includes a plurality of suction chambers. Each of the plurality of suction chambers is arranged between a circumferentially adjacent pair of the cylinder bores. The suction chamber communication passage includes a plurality of suction chamber communication passages that provide independent communication between the suction chambers and the shaft hole.

Accordingly, the suction chamber and cylinder bores are alternately arranged around the rotary valve along a circumferential direction. In order to communicate the cylinder bore and the suction chamber via the rotary valve, the intake passage is simply formed at a portion of the rotary valve to extend in the circumferential direction.

This simplifies the shape of the front rotary valve and therefore further shortens an axial length of the front rotary valve.

Preferably, the cylinder block includes a plurality of discharge chambers. Each of the discharge chambers is arranged in a space between adjacent cylinder bores.

Accordingly, when the cylinder blocks are thermally expanded due to the heat of the refrigerant discharged to the discharge chambers, thermally expanded portions are uniformly distributed in the cylinder blocks along the radial direction. This prevents each cylinder bore and each piston from adversely affected by a thermal expansion.

Preferably, the discharge chambers are arranged outward in a radial direction of the cylinder block from the suction chambers.

Preferably, the cylinder block includes a suction port to which an external pipe is connected, and a suction passage that provides communication between the suction port and the suction chamber. The suction passage is separated from the swash plate chamber.

Accordingly, the rotation shaft having a rotary valve receives heat generated by sliding friction due to the rotation of the rotation shaft. In a suction passage from the suction port via the front suction chamber to the front cylinder bore, heat exchange between the refrigerant and the rotation shaft is only carried out when the refrigerant passes through the rotary valve. In addition, an axial length of the rotary valve is shortened so that the refrigerant is sufficiently prevented from being heated. This improves the suction efficiency.

Preferably, the suction chamber communication passage is a recess formed in an inner wall of the shaft hole. The recess includes an open end in communication with the swash plate chamber. A thrust bearing is arranged between the swash plate and the open end of the recess. The thrust bearing closes the open end of the recess.

Accordingly, the suction chamber communication passage is formed together with when the cylinder block is molded. This reduces time for manufacturing the cylinder block as compared with the case in which the cylinder block is molded and then the cylinder block is subjected to a cutting work by a drill or the like to form the suction chamber communication passage.

Preferably, the suction chamber communication passage includes a first recess and a second recess. The first recess is formed in an inner wall of the suction chamber. The first recess includes an open end, which opens toward an end face of the cylinder block in an axial direction. The second recess is formed in an inner wall of the shaft hole. The second recess includes an open end in communication with the swash plate chamber. A thrust bearing is arranged between the swash plate and the open end of the second recess. The thrust bearing closes the open end of the second recess.

Accordingly, the suction chamber communication passage is formed together with when the cylinder block is molded. In addition, the size of an opening between the suction chamber communication passage and the swash plate chamber is reduced so that the size of the thrust bearing serving as a closing member can be reduced.

Preferably, the cylinder bores are three cylinder bores.

This sufficiently ensures volume of the suction chamber, and suppresses the pulsation.

Effects of the Invention

The present invention provides a swash plate compressor, which is decreased in size while suppresses pulsation and suction efficiency from being lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a double-headed piston type swash plate compressor according to a first embodiment of the present invention taken along line 1-1 in FIG. 3.

FIG. 2 is a cross-sectional view showing the double-headed piston type swash plate compressor according to the first embodiment taken along line 2-2 in FIG. 3.

FIG. 3 is a cross-sectional view showing a front discharge chamber and a front suction chamber taken along line 3-3 in FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 showing a front cylinder bore, the front suction chamber and the front discharge chamber.

FIG. 5 is a partial cross-sectional view showing a double-headed piston type swash plate compressor according to a second embodiment of the present invention.

FIG. 6 is a development view showing a rotary valve and inside of a shaft hole of FIG. 5.

FIG. 7( a) is a cross-sectional view taken along line 7a-7a of FIG. 5 showing a cylinder block as viewed from a front suction chamber.

FIG. 7( b) is a cross-sectional view taken along line 7b-7b of FIG. 5 showing a cylinder block as viewed from a shaft hole.

FIG. 8 is a partial cross-sectional view showing a double-headed piston type swash plate compressor of another example.

FIG. 9 is a cross-sectional view showing a double-headed piston type swash plate compressor of another example.

FIG. 10 is a development view showing a front rotary valve of another example.

FIG. 11 is a diagram showing a Patent Document 1.

FIG. 12 is a diagram showing a Patent Document 2.

FIG. 13 is a diagram showing a Patent Document 3.

EMBODIMENTS OF THE INVENTION

First Embodiment

A first embodiment of the present invention that embodies a swash plate compressor in a double-headed piston type swash plate compressor 10 will now be described with reference to FIGS. 1 to 4.

As shown in FIGS. 1 and 2, a double-headed piston type swash plate compressor 10 (hereinafter simply referred to as the compressor 10) includes a housing H. A cylinder block 11, which is located at a front side (left side as viewed in FIG. 1), is coupled to a front housing 13 with a front valve/port formation body 15 arranged in between. A cylinder block 12, which is located at a rear side (right side as viewed in FIG. 1), is coupled to a rear housing 14 with a rear valve/port formation body 16 arranged in between. The housing H is formed by the two cylinder blocks 11 and 12 and the front and rear housings 13 and 14 sandwiching the cylinder blocks 11 and 12.

A rotation shaft 22 is inserted into shaft holes 11a and 12a that are respectively formed in the cylinder blocks 11 and 12. The rotation shaft 22 is supported to be rotatable by sealing surfaces defined on the wall surfaces of the shaft holes 11a and 12a. The rotation shaft 22 is inserted through insertion holes 15d and 16d respectively formed in the centers of the front valve/port formation body 15 and the rear valve/port formation body 16. At an end of the rotation shaft 22 projecting from the front valve/port formation body 15, a lip type shaft seal 23 hermetically seals the space between the front housing 13 and the rotation shaft 22. The shaft seal 23 is accommodated in an accommodation chamber 13c defined between the inner wall surface of the front housing 13 and the circumferential surface of the rotation shaft 22.

A swash plate 24, which rotates integrally with the rotation shaft 22, is fixed to the rotation shaft 22. The swash plate 24 is arranged in the cylinder block 11, 12 and accommodated in a swash plate chamber 25, which is formed between the cylinder blocks 11 and 12. A thrust bearing 26 is arranged between the front cylinder block 11 and an annular base 24a of the swash plate 24. A thrust bearing 27 is arranged between the rear cylinder block 12 and the base 24a of the swash plate 24. The rotation shaft 22 has an axis L. The thrust bearings 26 and 27 sandwich the swash plate 24 to restrict movement of the swash plate 24 along the axial direction. The thrust bearings 26 and 27 are pushed respectively toward open ends of the shaft holes 11a and 12a in the cylinder blocks 11 and 12.

As shown in FIG. 4, three front cylinder bores 28 are arranged around the rotation shaft 22 in the front cylinder block 11. Further, referring to FIG. 1, three rear cylinder bores 29 are arranged around the rotation shaft 22 in the rear cylinder block 12. Each front cylinder bore 28 is paired with one of the rear cylinder bores 29. The front and rear cylinder bores 28 and 29 in each pair are aligned with each other in the axial direction (front to rear direction) in which the axis L extends. A double-headed piston 30 serving as a piston is inserted in each pair of the cylinder bore 28 and 29. The front cylinder bore 28 is closed by the front valve/port formation body 15 and the corresponding double-headed piston 30, and the rear cylinder bore 29 is closed by the rear valve/port formation body 16 and the corresponding double-headed piston 30.

Two shoes 31 arranged on opposite sides of the swash plate 24 transmit the rotational movement of the swash plate 24, which rotates integrally with the rotation shaft 22, to the double-headed pistons 30. This reciprocates each double-headed piston 30 in the corresponding front and rear cylinder bores 28 and 29. A front compression chamber 28a is defined in the front cylinder bore 28 by the double-headed piston 30 and the front valve/port formation body 15, and a rear compression chamber 29a is defined in the rear cylinder bore 29 by the double-headed piston 30 and the rear valve/port formation body 16.

The front housing 13 and cylinder block 11 include three front suction chambers 17, which surround the rotation shaft 22 and extend through the front valve/port formation body 15 in. As shown in FIG. 4, each of the three front suction chambers 17 are arranged between the front cylinder bores 28 that are circumferentially adjacent around the shaft hole 11a. The three front suction chambers 17 are arranged at equal interval at the outer side of the shaft hole 11a.

As shown in FIGS. 1 and 2, one of the three front suction chambers 17 has a longer length in the axial direction of the rotation shaft 22 and a greater volume than the other two front suction chambers 17. As shown in FIG. 3, each of the three front suction chambers 17 is in communication with the accommodation chamber 13c of the front housing 13. Thus, the three front suction chambers 17 are in communication with one another about the accommodation chamber 13c. This forms a single continuous space.

As shown in FIGS. 1 and 3, a front discharge chamber 28b is defined around the rotation shaft 22 between the front housing 13 and the front valve/port formation body 15. The front discharge chamber 28b is a region into which the refrigerant from the three front compression chambers 28a is discharged. Further, the front discharge chamber 28b is annular and defined in the peripheral portion of the front housing 13.

In the front discharge chamber 28b, each portion facing one of the front compression chambers 28a through the front valve/port formation body 15 forms an opening. In the front discharge chamber 28b, the portions facing the front compression chambers 28a are in communication with one another through passages. This forms a single continuous space.

As shown in FIGS. 3 and 4, three front discharge chambers 40, which are in communication with the front discharge chamber 28b, are defined in the cylinder block 11. The front discharge chambers 40 extend from the front cylinder block 11 and through the front valve/port formation body 15. The three front discharge chambers 40 are arranged around the rotation shaft 22. Each front discharge chamber 40 is formed between the front cylinder bores 28 that are adjacent in the circumferential direction of the shaft hole 11a. Further, the front discharge chambers 40 are located outward in the radial direction of the cylinder block 11 from the front suction chambers 17.

As shown in FIGS. 1 and 3, the front valve/port formation body 15 includes discharge ports 15a, which are arranged in correspondence with the front cylinder bores 28, and discharge valves 15b, which are arranged in correspondence with the discharge ports 15a. Further, the front valve/port formation body 15 includes retainers 15c, which restrict the open amount of the corresponding discharge valves 15b.

The rear structure will now be described.

As shown in FIGS. 1 and 2, three rear suction chambers 18 are arranged around the rotation shaft 22 (shaft hole 12a) and extend through the rear valve/port formation body 16 in the rear housing 14 and the cylinder block 12. In the same manner as the front side, each of the three rear suction chambers 18 is arranged in a space between the rear cylinder bores 29 that are adjacent in the circumferential direction of the shaft hole 12a. One of the three rear suction chambers 18 has a longer length in the axial direction of the rotation shaft 22 and a greater volume than the other two rear suction chambers 18.

A rear housing suction chamber 19 is defined between a central part of the rear housing 14 and the rear valve/port formation body 16. The three rear suction chambers 18 are in communication with one another in the rear housing suction chamber 19. Thus, the three rear suction chambers 18 are in continuous communication with one another about the rear housing suction chamber 19. Each front suction chamber 17 is paired with one of the rear suction chambers 18. The front suction chamber 17 and rear suction chamber 18 in each pair are aligned in the front to rear direction in which the axis L extends. The front suction chamber 17 and rear suction chamber 18 are formed at opposite sides of the swash plate 24 in the cylinder blocks 11 and 12.

An annular rear discharge chamber 29b is defined around the rotation shaft 22 between the rear housing 14 and the rear valve/port formation body 16. The rear discharge chamber 29b is a region into which the refrigerant from the three rear compression chambers 29a is discharged. Further, the rear discharge chamber 29b is defined at the outer side of the rear housing suction chamber 19. In the rear discharge chamber 29b, each portion facing one of the rear cylinder bores 29 through the rear valve/port formation body 16 forms an opening having a size that conforms to the circular rear compression chamber 29a. In the rear discharge chamber 29b, the portions facing the rear cylinder bores 29 are in communication with one another through passages. This forms a single continuous space.

The cylinder block 12 includes three rear discharge chamber 42, which are in communication with the rear discharge chamber 29b. The rear discharge chambers 42 extend from the rear housing 14 through the rear valve/port formation body 16 and to the rear cylinder block 12. The three rear discharge chambers 42 are arranged around the shaft hole 12a and formed between the rear cylinder bores 29 that are adjacent in the circumferential direction of the shaft hole 12a. The rear discharge chambers 42 are formed outward in the radial direction of the cylinder block 12 from the rear suction chambers 18. Each front discharge chamber 28b is paired with one of the rear discharge chambers 29b. The front discharge chamber 28b and rear discharge chamber 29b in each pair are aligned in the front to rear direction in which the axis L extends.

As shown in FIG. 1, the rear valve/port formation body 16 includes discharge ports 16a, which are arranged in correspondence with the rear discharge chambers 29b, and discharge valves 16b, which are arranged in correspondence with the discharge ports 16a. Further, the rear valve/port formation body 16 includes retainers 16c, which restrict the open amount of the discharge valves 16b.

A suction passage 43 is formed in the cylinder blocks 11 and 12. The suction passage 43 has a front opening, which is in communication with the front suction chamber 17 having the largest volume, and a rear opening, which is in communication with the rear suction chamber 18 having the largest volume. Further, a suction port 44 is formed in the front cylinder block 11. The suction port 44 has one end that opens in the outer surface of the cylinder block 11 and another end that opens in the wall surface of the suction passage 43. An external pipe 32 of an external refrigerant circuit that is arranged outside the compressor 10 is connected to one open end of the suction port 44. The suction passage 43 is formed in the cylinder blocks 11 and 12 and separated from the swash plate chamber 25.

The suction passage 43 is formed in communication with the front and rear suction chambers 17 and 18 having the largest volume. Thus, the suction passage 43 is sandwiched in the axial direction by the front discharge chamber 40 and the rear discharge chamber 42, which are located at the outer sides of the suction chambers 17 and 18.

As shown in FIG. 2, a discharge passage 45 is formed in the cylinder blocks 11 and 12. The discharge passage 45 has a front opening, which is in communication with one of the three front discharge chambers 40, and a rear opening, which is in communication with one of the three rear discharge chambers 42. Further, a discharge port 46 is formed in the cylinder block 11. The discharge port 46 has one end that opens in the outer surface of the cylinder block 11 and another end that opens in the wall surface of the discharge passage 45. The external pipe 33 of the external refrigerant circuit that is arranged outside the compressor 10, is connected to the discharge port 46.

As shown in FIG. 3, in the cylinder blocks 11 and 12, the discharge passage 45 is separated in the circumferential direction of the cylinder blocks 11 and 12 from the suction passage 43. More specifically, the front discharge chamber 40 and rear discharge chamber 42 sandwiching the discharge passage 45 in the axial direction is separated in the circumferential direction from the front discharge chamber 40 and rear discharge chamber 42 sandwiching the suction passage 43 in the axial direction.

When forming a refrigerating cycle for a vehicle air conditioner with the compressor 10, the external refrigerant circuit connects the discharge port 46 and the suction port 44 of the compressor 10 via the external pipes 32 and 33. The external refrigerant circuit includes a condenser, an expansion valve, and an evaporator, which are arranged in order from the discharge port 46 of the compressor 10 in the external refrigerant circuit.

The suction structure of the compressor 10 will now be described.

First, a front suction structure will be described. As shown in FIG. 4, suction chamber communication passages 50a communicating the front suction chambers 17 and the shaft hole 11a are formed in the cylinder block 11. Each suction chamber communication passage 50a has one end that opens in the corresponding front suction chamber 17 and another end that opens in the sealing surface of the wall defining the shaft hole 11a. The suction chamber communication passages 50a formed in the cylinder block 11 extend slightly inclined relative to the radial direction of the cylinder block 11.

Front bore communication passages 50b communicating the shaft hole 11a and the front cylinder bores 28 are formed in the cylinder block 11. Each front bore communication passage 50b has one end that opens in the sealing surface of the wall defining the shaft hole 11a and another end that opens in the corresponding front cylinder bore 28. The suction chamber communication passages 50a and front bore communication passages 50b are alternately arranged in the circumferential direction of the shaft hole 11a.

As shown in FIGS. 1 and 4, an intake groove 22a is formed in the circumferential surface of the front side of the rotation shaft 22. The intake groove 22a is recessed in the circumferential surface of the rotation shaft 22, which is a solid shaft, at the side closer to the front housing 13. The intake groove 22a opens towards the sealing surface of the wall defining the shaft hole 11a and is independently communicable with the suction chamber communication passages 50a and the front bore communication passages 50b. Rotation of the rotation shaft 22 changes the position of the intake groove 22a. This mechanically switches the suction chamber communication passages 50a and front bore communication passages 50b that come into communication with the intake groove 22a.

The portion of the rotation shaft 22 surrounded by the sealing surface forms a front rotary valve RF, which is formed integrally with the rotation shaft 22. The intake groove 22a communicates one of the suction chamber communication passage 50a and the front bore communication passage 50b that is adjacent in the circumferential direction of the shaft hole 11a. As the rotation shaft 22 rotates, the suction chamber communication passage 50a and front bore communication passage 50b that are independently in communication through the intake groove 22a draw in refrigerant from the corresponding front suction chamber 17 to the adjacent front cylinder bore 28. In the present embodiment, the intake groove 22a serves as a supplying passage, which communicates the front cylinder bore 28 and the front suction chamber 17 in the front rotary valve RF.

The rear intake structure will now be described.

As shown in FIGS. 1 and 2, rear intake passages 51 communicating the rear cylinder bores 29 and the shaft hole 12a are formed in the cylinder block 12. Each rear intake passage 51 has one end that opens in the corresponding rear cylinder bore 29 and another end that opens in the sealing surface of the wall defining the shaft hole 12a. A supply passage 22b is formed in the circumferential surface of the rear side of the rotation shaft 22. The supply passage 22b has one end that opens in the rear housing suction chamber 19 of the rear housing 14 and another end that is communicable with the rear intake passages 51. Rotation of the rotation shaft 22 changes the position of the supply passage 22b. This mechanically switches the rear intake passages 51 that come into communication with the supply passage 22b. The portion of the rotation shaft 22 surrounded by the sealing surface forms a rear rotary valve RR, which is formed integrally with the rotation shaft 22.

The operation of the compressor 10 will now be described.

Refrigerant is drawn through the suction port 44 into the suction passage 43 and supplied to each front suction chamber 17 and each rear suction chamber 18. When each front cylinder bore 28 performs the intake stroke, one of the suction chamber communication passages 50a and the adjacent front bore communication passage 50b come into communication through the intake groove 22a of the front rotary valve RF, as shown in FIG. 4. The refrigerant is then drawn from the front suction chamber 17 through the front rotary valve RF into the corresponding front cylinder bore 28.

As the rotation shaft 22 further rotates, the intake groove 22a goes out of communication with the suction chamber communication passage 50a. In this state, the suction chamber communication passage 50a and the front bore communication passage 50b are not in communication with each other, and the front cylinder bore 28 is closed. Then, the front cylinder bore 28 performs the compression stroke and discharge stroke. The refrigerant in the front compression chamber 28a is forced through the discharge valve 15b from the discharge port 15a and discharged to the front discharge chamber 28b. The refrigerant discharged to the front discharge chamber 28b flows out of the front discharge chamber 40 through the discharge passage 45 and the discharge port 46 and into the external refrigerant circuit.

At the rear side, when each rear cylinder bore 29 performs the intake stroke in a state in which refrigerant is supplied to the rear housing suction chamber 19, the supply passage 22b, which is in communication with the rear housing suction chamber 19 in the rear rotary valve RR, comes into communication with one or two rear intake passage 51. This supplies refrigerant to the rear intake passage 51 from the rear housing suction chamber 19 through the rear rotary valve RR, and the refrigerant is drawn into the rear cylinder bore 29, which is in communication with the rear intake passage 51.

As the rotation shaft 22 further rotates, the supply passage 22b goes out of communication with the rear intake passage 51. In this state, the rear intake passage 51 and the rear housing suction chamber 19 are not in communication with each other, and the rear cylinder bore 29 is closed.

Then, the rear cylinder bore 29 performs the compression stroke and the discharge stroke. The refrigerant in the rear compression chamber 29a is forced through the discharge valve 16b from the discharge port 16a and discharged to the rear discharge chamber 29b. The refrigerant discharged to the rear discharge chamber 29b flows out of the rear discharge chamber 42 through the discharge passage 45 and the discharge port 46 and into the external refrigerant circuit.

Accordingly, the present embodiment has the advantages described below.

(1) In the double-headed piston type swash plate compressor 10, the three front cylinder bores 28 are formed around the shaft hole 11a of the cylinder block 11, and each front suction chamber 17 is arranged between the front cylinder bores 28 that are adjacent to each other. That is, the front cylinder bores 28 and the front suction chambers 17 are alternately arranged around the shaft hole 11a. In addition, the suction chamber communication passages 50a, which communicates front suction chambers 17 with the shaft hole 11a, and the front bore communication passages 50b, which communicates the front cylinder bores 28 with the shaft hole 11a, are formed in the cylinder block 11. The suction chamber communication passages 50a and the front bore communication passages 50b are alternately arranged in the circumferential direction of the shaft hole 11a. In the cylinder block 11, the refrigerant in each front suction chamber 17 is directly drawn into the intake groove 22a through the corresponding suction chamber communication passage 50a, and then drawn in the front cylinder bore 28 through the front bore communication passage 50b.

Accordingly, in order to communicate the front cylinder bore 28 and the circumferentially adjacent front suction chamber 17 via the rotary valve RF, the intake groove 22a is simply formed at a portion of the rotary valve RF to extend in the circumferential direction. This simplifies the shape of the front rotary valve RF and therefore shortens an axial length of the front rotary valve RF. Thus, the compressor 10 is prevented from enlarging the body size in both the axial direction and the radial direction if the front rotary valve RF is provided in the compressor 10, which includes the suction chamber 17 formed in the cylinder block 11. In this manner, a rotary valve is used instead of a suction valve to draw refrigerant, and the front cylinder bores 28 are mechanically communicated with the front suction chamber 17. This prevents the suction efficiency from decreasing and is in contrast with a suction valve. In addition, three front suction chambers 17 are formed in the cylinder block 11. This sufficiently ensures volume of the suction chamber, and suppresses the pulsation.

(2) Each front suction chamber 17 is formed between the front cylinder bores 28 that are adjacent in the circumferential direction of the shaft hole 11a. In the cylinder block 11, the suction chamber communication passages 50a communicate the front suction chambers 17 and the intake groove 22a of the front rotary valve RF. Refrigerant is directly drawn from each front suction chamber 17 into the intake groove 22a through the corresponding suction chamber communication passage 50a. Thus, the refrigerant does not need to be drawn into the suction pressure region of the front housing 13, and the intake groove 22a does not need to extend from the front housing 13 to the cylinder block 11 in the rotation shaft 22. In this manner, the rotation shaft 22 is supported by the shaft hole 11a (sealing surface) at the front and rear of the intake groove 22a in the axial direction, the bearing area for the rotation shaft 22 is ensured, and the abrasion resistance is increased.

(3) In the same manner as the front suction chambers 17, each rear suction chamber 18 is formed between adjacent rear cylinder bores 29 around the rotation shaft 22. Thus, the suction chambers 17 and 18 are arranged in the radial direction of the cylinder blocks 11 and 12 at the front and rear sides. This avoids enlargement of the compressor 10 in the axial direction.

(4) The front housing 13 includes the front discharge chamber 28b, and the rear housing 14 includes the rear discharge chamber 29b. The three front discharge chambers 40 are in communication with the front discharge chamber 28b, and the three rear discharge chambers 42 are in communication with the rear discharge chambers 29b. Each of the discharge chambers 40 and 42 is arranged between adjacent cylinder bores 28 and 29. Thus, the discharge chambers 40 and 42 each having large volume can be ensured, and the pulsation can be further reduced.

(5) The discharge chambers 40 and 42 are arranged at the outer side of the suction chambers 17 and 18 in the radial direction of the cylinder blocks 11 and 12. Thus, when the cylinder blocks 11 and 12 are thermally expanded due to the heat of the refrigerant discharged to the discharge chambers 40 and 42, thermally expanded portions are uniformly distributed in the cylinder blocks 11 and 12 along the radial direction. This prevents the double-headed piston 30 from adversely affected by a thermal deformation of the cylinder bores 28 and 29.

(6) Each of the discharge chambers 40 and 42 is between the cylinder bores 28 and 29. Thus, even when the cylinder blocks 11 and 12 are thermally expanded due to the high-temperature refrigerant discharged to the discharge chambers 40 and 42, thermally expanded portions are evenly distributed in the circumferential direction of the cylinder blocks 11 and 12. This prevents the double-headed piston 30 from being adversely affected by a thermal deformation of the cylinder bores 28 and 29.

(7) The suction port 44 is formed in the cylinder block 11, and the suction passage 43, which communicates the front suction chamber 17 and the rear suction chamber 18, is formed in the cylinder blocks 11 and 12. Thus, when refrigerant is drawn into the suction chambers 17 and 18, the refrigerant does not flow through the swash plate chamber 25. This prevents the refrigerant that is drawn into the suction chambers 17 and 18 from being heated by the high-temperature blow-by gas and the rotation shaft 22 heated by a sliding friction in the swash plate chamber 25.

(8) Pairs of the front suction chamber 17 and rear suction chamber 18 are formed in the axial direction, and pairs of the front discharge chamber 40 and rear discharge chamber 42 are formed in the axial direction. Further, the front rotary valve RF is used for the front cylinder bores 28, and the rear rotary valve RR is used for the rear cylinder bores 29. Thus, the suction structure is the same at the front and rear sides. This prevents the occurrence of vibration and noise that would be caused by a difference in the suction structure between the front and rear sides.

(9) Each front suction chamber 17 is formed between front cylinder bores 28, which are adjacent in the circumferential direction around the shaft hole 11a. The suction chamber communication passages 50a, which communicate the front suction chambers 17 and the intake groove 22a of the front rotary valve RF, and the front bore communicating passages 50b, which communicating the intake groove 22a and the front cylinder bores 28, are formed in the cylinder block 11. Refrigerant is drawn from each front suction chamber 17 into the corresponding front cylinder bore 28 through the suction chamber communication passage 50a, the intake groove 22a, and the front bore communication passage 50b. Thus, refrigerant is drawn from the front suction chamber 17 to the front cylinder bore 28 within the cylinder block 11. This reduces a contacting area between the refrigerant and the intake groove 22a compared to when the refrigerant is drawn into the front cylinder bores 28 through a groove, which extends into the front housing 13 and the swash plate chamber 25. This reduces suction heating that would be caused when the contacting area is large, and prevents the suction efficiency from decreasing.

(10) The rotation shaft 22 receives heat generated by sliding friction between the rotation shaft 22 and the shaft holes 11a and 12a or the like. In a suction passage from the suction port 44 via the front suction chamber 17 to the front cylinder bore 28, heat exchange is carried out between the refrigerant and the rotation shaft 22 through the front rotary valve RF when the refrigerant passes through the intake groove 22a. The intake groove 22a has a short length so that the refrigerant is sufficiently prevented from being heated. This improves the suction efficiency.

Second Embodiment

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 7. The same constituents as those in the first embodiment are given the same reference numerals and overlapping description thereof is omitted or simplified.

As shown in FIGS. 5 and 7(a), a first recess 60 corresponding to each front suction chamber 17 is formed at a portion of a first end face 11b, which is a surface of a cylinder block 11 closer to a front housing 13, located outside of a shaft hole 11a. The first recess 60 is formed in the cylinder block 11 to extend from an inner wall of each front suction chamber 17 in a radial direction. One end of the first recess 60 opens toward the first end face 11b, which is a surface of the cylinder block 11 in an axial direction, and is connected with an open end of each front suction chamber 17. The other end of the first recess 60 is located in the middle of the front suction chamber 17 in the axial direction, and does not extend through the cylinder block 11 in the axial direction. The first recess 60 is depressed from the first end face 11b toward a second end face 11c.

As shown in FIGS. 5 and 7(b), a second recess 61 corresponding to each front suction chamber 17 is formed at the second end face 11c, which is a surface of the cylinder block 11 closer to the front housing 13a. The second recess 61 is formed in the cylinder block 11 to extend from the inner wall of each front suction chamber 17 in the radial direction. One end of the second recess 61 opens toward the second end face 11c of the cylinder block 11, and is connected with an open end of the shaft hole 11a. The other end of the second recess 61 is located in the middle of the shaft hole 11a in the axial direction, and does not extend through the cylinder block 11 in the axial direction. The second recess 61 is depressed from the second end face 11c toward the first end face 11b. An open end of the second recess 61 closer to the second end face 11c (closer to a swash plate chamber 25) is closed by a thrust bearing 26.

In the cylinder block 11, the first recess 60 and the second recess 61 are connected and in communication with each other thereby forming a suction chamber communication passage 62. One end of the suction chamber communication passage 62 is defined by an open end of the first recess 60 closer to the front suction chamber 17, and the other end of the suction chamber communication passage 62 is defined by an open end of the second recess 61 closer to the shaft hole 11a. The front suction chamber 17 and an intake groove 22a are communicable through the suction chamber communication passage 62. An open end of the suction chamber communication passage 62 closer to the swash plate chamber 25 is closed by the thrust bearing 26, and a clearance between the suction chamber communication passage 62 and the swash plate chamber 25 is sealed. The first recess 60 and the second recess 61 are formed together with the front suction chamber 17 when the cylinder block 11 is molded.

FIG. 6 is a diagram showing a front rotary valve RF developed in a circumferential direction. An outline shown by a solid line indicates a peripheral surface of the front rotary valve RF and the shaft hole 11a, which receives and supports the front rotary valve RF. The intake groove 22a is shown in the outline. In FIG. 6, dashed-two dotted line indicates a front bore communication passage 50b and the suction chamber communication passage 62 (an overlapping region between the first recess 60 and the second recess 61). The front bore communication passage 50b opens toward the shaft hole 11a and communicates with each front cylinder bore 28. The suction chamber communication passage 62 opens toward the shaft hole 11a and communicates with each front suction chamber 17.

As shown in FIG. 6, the front bore communication passage 50b and the suction chamber communication passage 62 are alternately arranged in the circumferential direction of the shaft hole 11a. In order to communicate the suction chamber communication passage 62 and the front bore communication passage 50b via the intake groove 22a, the intake groove 22a is formed at a portion of the rotation shaft 22 and extends in the circumferential direction.

Accordingly, the second embodiment has the advantages described below in addition to the same advantages of (1) to (10) of the first embodiment.

(11) The suction chamber communication passage 62 has a rectangular shape axially elongated. Accordingly, the suction chamber communication passage 62 and the front bore communication passage 50b are alternately arranged in the shaft hole 11a and separate from each other so as to ensure sealing ability therebetween. Thus, in order to communicate the front cylinder bore 28 and the circumferentially adjacent front suction chamber 17 via the rotary valve RF, the suction chamber communication passage 62 and the adjacent front bore communication passage 50b only have to communicate with each other by the intake groove 22a. For this, the intake groove 22a is simply formed at a portion of the rotary valve RF and extends in the circumferential direction. This simplifies the shape of the front rotary valve RF formed in the rotation shaft 22 and therefore shortens an axial length of the front rotary valve RF. Thus, the compressor 10 is prevented from enlarging the body size in the axial direction when the front rotary valve RF is provided in the compressor 10, which includes the suction chamber 17 formed in the cylinder block 11.

(12) The suction chamber communication passage 62 is formed together with the front suction chamber 17 when the cylinder block 11 is molded. This reduces time for manufacturing the cylinder block 11 as compared with the case in which the cylinder block 11 is molded and then the cylinder block 11 is subjected to a cutting work by a drill or the like to form the suction chamber communication passage 62.

(13) The suction chamber communication passage 62 is formed by combining the first recess 60 extending from the first end face 11b and the second recess 61 extending from the second end face 11c. This suppresses an opening area of the second recess 61 as compared with the case in which the suction chamber communication passage is formed only by the second recess 61. Thus, the open end of the second recess 61 can be closed by the thrust bearing, which is relatively small in size.

The first and second embodiments may be varied as described hereafter.

In the embodiment described above, the suction chamber communication passage 62 is formed by combining the first recess 60 extending from the first end face 11b and the second recess 61 extending from the second end face 11c, but is not limited to this. As shown in FIG. 8, in case that the thrust bearing 26 has a diameter, which is sufficiently large, the suction chamber communication passage may be formed only by a second recess 66 extending from a second end face 11c of a cylinder block 11. The second recess 66 enables a front suction chamber 17 to directly communicate with an intake groove 22a.

As shown in FIG. 9, an intake pathway for drawing refrigerant gas to the front cylinder bore 28 may have a pathway passing through an in-shaft passage 65 and in communication with the rear housing suction chamber 19, in addition to a pathway, which extends from the suction chamber communication passage 62 to the front bore communication passage 50b via the front rotary valve RF. According to this configuration, refrigerant is drawn not only through the pathway extending from the rear housing suction chamber 19 via the in-shaft passage 65 but also through the pathway extending from the front suction chamber 17 to the front cylinder bore 28 via the suction chamber communication passage 62. This reduces size of the diameter of the in-shaft passage 65. Thus, the rotation shaft 22 and the rotary valve are reduced in size in the diameter direction, and the body of the entire compressor 10 is reduced in size.

In the embodiment described above, rotary valves are used at the front and rear sides to drawn refrigerant. However, the rear side may use a suction valve instead of the rotary valve.

In the embodiment described above, at the rear side, refrigerant of the rear suction chambers 18 is collected in the rear housing suction chambers 19. Then, the refrigerant is drawn from the rear housing suction chambers 19 into the rear cylinder bores 29 through the rear rotary valve RR. However, the rear side is not limited in such a manner. Instead, the rear side may also be formed so that the rear suction chambers 18 and the shaft hole 12a are communicated by communication passages through an intake groove, the shaft hole 12a and the rear cylinder bores 29 are communicated by intake passages, and refrigerant is drawn from the rear suction chamber 18 into the rear cylinder bores 29 through the communication passages, the intake groove of the rear rotary valve RR, and the intake passages.

In the embodiment described above, the suction port 44 is formed in the front cylinder block 11. The suction port 44 may be formed in another portions in the housing H, for example, in the rear cylinder block 12.

In the embodiment described above, the refrigerant that has passed through the suction port 44 is supplied to the front suction chambers 17 and the rear suction chambers 18 through the suction passage 43 formed in the cylinder blocks 11 and 12. However, the refrigerant that passes through the suction port 44 may be supplied to the front suction chambers 17 and the rear suction chambers 18 through the swash plate chamber 25.

In the embodiment described above, each of the three front discharge chambers 40 is arranged between adjacent front cylinder bores 28. However, the front discharge chambers 40 may be collectively formed at one or two locations. In this configuration, as shown in FIG. 10, a part of the intake groove 22a is formed to have a ring shape that extend along an entire peripheral surface of the rotation shaft 22 closer to a front end of the compressor.

Further, each of the three rear discharge chambers 42 is arranged between adjacent rear cylinder bores 29. However, the rear discharge chambers 42 may be collectively formed at one or two locations.

In the embodiment described above, three rear suction chambers 18 are formed, and each rear suction chamber 18 is arranged between adjacent rear cylinder bores 29. Instead, the rear suction region may be formed by just the rear housing suction chamber 19, and the rear suction chamber 18 may be collectively formed at one or two locations.

In the embodiment described above, the front suction chamber 17 that is in communication with the suction passage 43 has a greater volume than the other two front suction chambers 17. Instead, the volume of each of the other two front suction chambers 17 may be greater than the volume of the front suction chamber 17 that is in communication with the suction passage 43. In such a structure, refrigerant is directly supplied from the suction passage 43. Thus, the front suction chambers 17 that are in communication with the suction passage 43 may have a small volume so that the refrigerant is smoothly supplied to the front cylinder bores 28. In contrast, in the other two front suction chambers 17, refrigerant is first supplied to the accommodation chamber 13c before being supplied to the front cylinder bores 28. Thus, refrigerant is smoothly supplied to the front cylinder bores 28. This ensures a large volume and supplies a greater amount of refrigerant.

The three front suction chambers 17 may have the same volume.

In the embodiment described above, the front suction chambers 17 and the front discharge chamber 40 are formed extending over both of the front housing 13 and the cylinder block 11 but may be formed in only the cylinder block 11.

In the embodiment described above, the rear suction chambers 18 and the rear discharge chamber 42 are formed extending over both of the rear housing 14 and the cylinder block 12 but may be formed in only the cylinder block 12.

In the embodiment described above, the swash plate compressor is embodied in the double-headed piston type swash plate compressor. However, the swash plate compressor may be changed to a single-headed piston type swash plate compressor including a single-headed piston connected with the swash plate 24 instead of the double-headed piston 30.

Explanation of Reference Numerals

RF . . . front rotary valve serving as rotary valve, 10 . . . double-headed piston type swash plate compressor, 11 and 12 . . . cylinder block, 11a and 12a . . . shaft hole, 17 . . . front suction chamber, 18 . . . rear suction chamber, 22 . . . rotation shaft, 22a . . . intake groove, 24 . . . swash plate, 25 . . . swash plate chamber, 26 and 27 . . . thrust bearing, 28 . . . front cylinder bore serving as cylinder bore, 28b . . . front discharge chamber serving as discharge chamber, 29 . . . rear cylinder bore serving as cylinder bore, 29b . . . rear discharge chamber serving as discharge chamber, 30 . . . double-headed piston, 32 and 33 . . . external pipe, 40 . . . front discharge chamber serving s discharge chamber, 42 . . . rear discharge chamber serving as discharge chamber, 43 . . . suction passage, 44 . . . suction port, 50a . . . suction chamber communication passage, 50b . . . front bore communication passage, 60 . . . first recess, 61 and 66 . . . second depression, 62 . . . suction chamber communication passage

Claims

1. A swash plate compressor comprising: a cylinder block including a shaft hole, cylinder bores, a swash plate chamber and a suction chamber, wherein the shaft hole extends through the cylinder block, the cylinder bores are arranged along a circumferential direction around the shaft hole, and the suction chamber is arranged in a space between the adjacent cylinder bores and is separated from the swash plate chamber;a swash plate accommodated in the swash plate chamber;pistons connected with the swash plate and respectively arranged in the cylinder bores;a rotation shaft arranged in the shaft hole and operative to rotate integrally with the swash plate; anda rotary valve provided with the rotation shaft to rotate integrally with the rotation shaft;wherein the cylinder block includes a suction chamber communication passage that defines a communication path between the suction chamber and the the shaft hole, and bore communication passages that define independent communication paths between the cylinder bores and the shaft hole,wherein the rotary valve rotates integrally with the rotation shaft to provide sequential communication between the suction chamber communication passage and the bore communication passages.

2. The swash plate compressor according to claim 1, wherein the suction chamber includes a plurality of suction chambers, each of the plurality of suction chambers is arranged between a circumferentially adjacent pair of the cylinder bores,the suction chamber communication passage includes a plurality of suction chamber communication passages that provide independent communication between the suction chambers and the shaft hole.

3. The swash plate compressor according to claim 2, wherein the cylinder block includes a plurality of discharge chambers, each of the discharge chambers is arranged in a space between adjacent cylinder bores.

4. The swash plate compressor according to claim 3, wherein the discharge chambers are arranged outward in a radial direction of the cylinder block from the suction chambers.

5. The swash plate compressor according to claim 1, wherein the cylinder block includes a suction port to which an external pipe is connected, and a suction passage that provides communication between the suction port and the suction chamber,the suction passage is separated from the swash plate chamber.

6. The swash plate compressor according to claim 1, wherein the suction chamber communication passage is a recess formed in an inner wall of the shaft hole, the recess including an open end in communication with the swash plate chamber,a thrust bearing is arranged between the swash plate and the open end of the recess, andthe thrust bearing closes the open end of the recess.

7. The swash plate compressor according to claim 1, wherein the suction chamber communication passage includes a first recess and a second recess, the first recess formed in an inner wall of the suction chamber, the first recess including an open end, which opens toward an end face of the cylinder block in an axial direction, the second recess formed in an inner wall of the shaft hole, the second recess including an open end in communication with the swash plate chamber,a thrust bearing is arranged between the swash plate and the open end of the second recess, andthe thrust bearing closes the open end of the second recess.

8. The swash plate compressor according to claim 1, wherein the cylinder bores are three cylinder bores.