US20030118456A1

US20030118456A1 - Swash plate-type compressors

Info

Publication number: US20030118456A1
Application number: US10/315,975
Authority: US
Inventors: Hiroyuki Endo
Original assignee: Individual
Current assignee: Sanden Corp
Priority date: 2001-12-17
Filing date: 2002-12-11
Publication date: 2003-06-26
Also published as: JP2003184738A

Abstract

A swash plate-type compressor includes a housing having a cylinder block with a plurality of cylinder bores formed therethrough. The cylinder block encloses a crank chamber, a suction chamber, and a discharge chamber. The compressor also includes a drive shaft rotatably supported by the housing, a plurality of pistons positioned within a corresponding one of the cylinder bores, and a swash plate rotatably mounted on the drive shaft. The compressor further includes a discharge path formed between the crank chamber and the suction chamber. Moreover, the compressor includes a check valve positioned within the discharge path. The check valve is adapted to open the discharge path when a first pressure in the crank chamber is greater than a second pressure in the suction chamber and to close the discharge path when the first pressure is less than or equal to the second pressure. Consequently, a refrigerant within the crank chamber is discharged into the suction chamber when the first pressure is greater than the second pressure. Nevertheless, the refrigerant within the suction chamber is not discharged into the crank chamber when the first pressure is less than or equal to the second pressure.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to swash plate-type compressors used in automotive air conditioning systems. In particular, the present invention is directed towards swash plate-type compressors having a discharge path between a crank chamber and a suction chamber, and a check valve for opening and closing the discharge path based on the pressure in the crank chamber and the suction chamber, respectively.

2. Description of Related Art

Known swash plate-type compressors include a cylinder block, a front housing, a valve plate, and a cylinder head. The cylinder block is substantially cylindrical, and also is enclosed by the front housing and the cylinder head. Such known compressors also include a crank chamber formed between the cylinder block and the front housing, and a suction chamber and a discharge chamber formed within the cylinder head adjacent to the value plate. Moreover, such known compressors include an inlet port and an outlet port adapted to communicate with the suction chamber and the discharge chamber, respectively. The inlet port and the outlet port are connected to a refrigerant circuit of an air conditioning system of a vehicle. The cylinder block, the front housing, the valve plate, and the cylinder head are attached fixably to each other by a plurality of bolts. Such known compressors further include a plurality of cylinder bores formed in the cylinder block, and the cylinder bores are arranged radially with respect to a central axis of the cylinder block.

Such known compressors also include a drive shaft, a swash plate, a plurality of shoes, and a plurality of pistons. The drive shaft extends along a central axis of the compressor through the crank chamber, and also is supported rotatably by the front housing and the cylinder block via a pair of bearings mounted in the front housing and the cylinder block, respectively. Such known compressors also include an electromagnetic clutch, and a drive belt is used to engage the electromagnetic clutch by transmitting a drive force from a crankshaft of an engine of the vehicle to the electromagnetic clutch. When the electromagnetic clutch is engaged, the driving force also is transmitted from the electromagnetic clutch to the drive shaft. Moreover, the swash plate is positioned within the crank chamber, and is mounted slidably on the draft shaft, such that an inclination angle of the swash plate varies relative to a radial line which extends perpendicular to the drive shaft.

Moreover, each piston is positioned within a corresponding cylinder bore, and the pistons reciprocate independently within their corresponding cylinder bore. Each of the pistons also is connected to the swash plate via a pair of shoes. In such known compressors, a discharge path is adapted to provide fluid communication between the crank chamber and the suction chamber. When a refrigerant is compressed, the refrigerant leaks into the crank chamber via a clearance between each piston and their corresponding cylinder bore, and accumulates within the crank chamber. Moreover, the accumulated refrigerant subsequently is discharged into the suction chamber.

Nevertheless, when such known compressors are not in operation, and a temperature of an evaporator or a condenser in the refrigerant circuit is greater than a temperature of the compressor, the refrigerant flows into the crank chamber from the suction chamber via the discharge path. Similarly, when a pressure in the suction chamber is greater than a pressure in,the crank chamber, and a temperature of refrigerant in the evaporator or the condenser is greater than a saturated temperature of the refrigerant, the refrigerant flows into the crank chamber from the suction chamber via the discharge path, the refrigerant cools into a liquid which accumulates in the crank chamber. Subsequently, when the operation of the compressor begins, lubricant oil, which is on a surface of the swash plate and a surface of each piston, is washed away by the liquid refrigerant accumulated in the crank chamber, and the lubricant oil and the liquid refrigerant are discharged from the crank chamber into the suction chamber via the discharge path. Thus, an amount of lubricant oil at a sliding portion between an exterior surface of the swash plate and an exterior surface of each shoe, and an amount of lubricant oil at a sliding portion between an exterior surface of each piston and an interior surface of their corresponding cylinder bores, are reduced. Consequently, an amount of friction at the sliding portion between the swash plate and the shoes and an amount of friction at the sliding portion between the pistons and their corresponding cylinder bores increase.

SUMMARY OF THE INVENTION

Therefore, a need has arisen for swash plate-type compressors which overcome these and other shortcomings of the related art. A technical advantage of the present invention is that when a swash plate-type compressor is not in operation, a liquid refrigerant does not accumulate in the crank chamber of the compressor.

According to an embodiment of the present invention, a swash plate-type compressor is described. The swash plate-type compressor comprises a housing having a cylinder block with a plurality of cylinder bores formed therethrough. The cylinder block encloses a crank chamber, a suction chamber, and a discharge chamber. The compressor also comprises a drive shaft rotatably supported by the housing; a plurality of pistons each of which is positioned within a corresponding one of the cylinder bores, and a swash plate rotatably mounted on the drive shaft. The compressor further comprises a discharge path formed between the crank chamber and the suction chamber. Moreover, the compressor comprises a check valve positioned within the discharge path. The check valve is adapted to open the discharge path when a first pressure in the crank chamber is greater than a second pressure in the suction chamber, and to close the discharge path when the first pressure is less than or equal to the second pressure. Consequently, a refrigerant within the crank chamber is discharged into the suction chamber via the discharge path when the first pressure is greater than the second pressure. Nevertheless, the refrigerant within the suction chamber is not discharged back into the crank chamber when the first pressure is less than or equal to the second pressure.

Other objects, features, and advantages of the present invention will be apparent to persons of ordinary skill in the art in view of the foregoing detailed description of the invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, needs satisfied thereby, and the objects, features, and advantages thereof, reference now is made to the following description taken in connection with the accompanying drawings. [0011]
FIG. 1 is a cross-sectional view of a swash plate-type compressor, according to an embodiment of the present invention. [0012]
FIG. 2 is a partial, enlarged cross-sectional view of the compressor of FIG. 1. [0013]
FIG. 3 is a cross-sectional view of a swash plate-type compressor, according to another embodiment of the present invention. [0014]
FIG. 4 is a partial, enlarged cross-sectional view of a swash plate-type compressor, according to yet another embodiment of the present invention. [0015]

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the present invention, and their features and advantages, may be understood by referring to FIGS. [0016] 1-4, like numerals being used for corresponding parts in the various drawings.
Referring to FIGS. 1 and 2, a swash plate-[0017] type compressor 100 according to an embodiment of the present invention is depicted. As shown in FIG. 1, compressor 100 may comprise a cylinder block 1, a front housing 2, a valve plate 6, and a cylinder head 4. Cylinder block 1 may be substantially cylindrical and also may be enclosed by front housing 2 and cylinder head 4. Compressor 100 also may comprise a crank chamber 3 formed between cylinder block 1 and front housing 2. Moreover, compressor 100 may comprise a suction chamber 8 and a discharge chamber 9 formed within cylinder head 8 adjacent to valve plate 6. Compressor 100 further may comprise an inlet port (not shown) and an outlet port (not shown), which may be adapted to communicate with suction chamber 8 and discharge chamber 9, respectively. The inlet port and the outlet port may be connected to a refrigerant circuit (not shown) of an air conditioning system of a vehicle. Cylinder block 1, front housing 2, valve plate 6, and cylinder head 4 may be fixable attached to each other by a plurality of bolts 50. Compressor 100 also may comprise a plurality of cylinder bores 1 a formed in cylinder block 1, and cylinder bores 1 a may be arranged radially with respect to a central axis of cylinder block 1.
[0018] Compressor 100 further may comprise a drive shaft 10, a swash plate 11, a plurality of shoe pairs 12, and a plurality of pistons 13. Drive shaft 10 may extend along a central axis of compressor 100 through crank chamber 3. Drive shaft 10 also may be supported rotatably by front housing 2 via a bearing 20 a mounted in front housing 2, and by cylinder block 1 via a plurality of bearings 20 b mounted in a center bore 1 b formed at a center of cylinder block 1. Swash plate 11 may be positioned within crank chamber 3, and may be mounted fixedly on drive shaft 10. Each shoe 12 may engage a sliding surface of swash plate 11, and may be in slidable contact with the sliding surface of swash plate 11. Shoes 12 may be positioned radially in a circumferential direction at a regular interval with respect to each other. Each pair of shoes 12 also may engage slidably one of piston 13. As such, each piston 13 may be in contact with swash plate 11 via one pair of shoes 12. Moreover, each piston 13 may be positioned within a corresponding cylinder bore 1 a and may reciprocate independently within corresponding cylinder bore 1 a.
Center bore [0019] 1 b of cylinder block 1 may be in communication with suction chamber 8 via a refrigerant path (not shown), and a discharge path comprises center bore 1 b and the refrigerant path. When a refrigerant is compressed, the refrigerant may leak into crank chamber 3 via a sliding portion between an exterior surface of piston 13 and an interior surface of cylinder bore 1 a.
A [0020] check valve 14 may be positioned within center bore 1 b. As shown in FIG. 2, check valve 14 may comprise a case 14a having a cylindrical shape and a bottom wall 14 k. Case 14 a may be fitted with center bore 1 b, and a contact portion between case 14 a and center bore 1 b may be sealed by an O-ring 14 b. A plurality of openings 14 c adapted to lock an annular valve seat 14 d may be formed through a flange, and the flange may be formed at an open end 14 j of case 14 a. Valve seat 14 d may contact open end 14 j of case 14 a when a plurality of hooks 14 d′ of valve seat 14 d are inserted inside the plurality of openings 14 c of case 14 a. A plurality of vents 14 e may be formed through bottom wall 14 k of case 14 a, and a spring 14 f may be positioned within case 14 a. A valve element 14 g may be fixed to an end of spring 14 f at a side of crank chamber 3, and a plurality of supports 14 h may extend from case 14 a toward suction chamber 8.
When [0021] compressor 100 is in operation, drive shaft 10 may rotate via an external power source, e.g., an engine of a vehicle, and swash plate 11 may rotate substantially simultaneously with drive shaft 10 about an axis of drive shaft 10. When swash plate 11 rotates, each piston 13 may reciprocate within their corresponding cylinder bores 1 a. When pistons 13 reciprocate within their corresponding cylinder bores 1 a, refrigerant, which is introduced into suction chamber 8 via the inlet port, may be drawn into each cylinder bore 1 a via suction ports 5, and the refrigerant subsequently may be compressed by pistons 13. When the refrigerant is compressed, a discharge reed valve 7 a may open, and the refrigerant may be discharged from cylinder bores 1 a into discharge chamber 9 via a discharge port 7 b formed through a valve plate 6. Moreover, the refrigerant then may be discharged from discharge chamber 9 into the refrigerant circuit via the outlet port.
Nevertheless, as described above, when [0022] compressor 100 is in operation, refrigerant may leak into crank chamber 3 via the sliding portion between each piston 13 and their corresponding cylinder bores 1 a. Moreover, during operation, or after the operation of compressor 100 stops, if a pressure Pc in crank chamber 3 is greater than a pressure Ps in suction chamber 8, valve element 14 g moves away from valve seat 14 d. When valve element 14 g moves away from valve seat 14 d, the discharge path comprising center bore 1 b and the refrigerant path opens. As such, the refrigerant in crank chamber 3 may be discharged into suction chamber 8 via the discharge path. Because supports 14 h may be in contact with valve plate 6, however, a plurality of vents 14 e formed through the bottom wall of case 14 a may remain open when valve element 14 g moves away from valve seat 14 d. In contrast, if the pressure Pc in crank chamber 3 is less than or equal to the pressure Ps in suction chamber 8, valve element 14 g contacts valve seat 14 d, which closes the discharge path. Consequently, the refrigerant does not flow from suction chamber 8 to crank chamber 3 via the discharge path.
After the operation of [0023] compressor 100 has been stopped for a predetermined period of time, a temperature of an evaporator or a condenser in the refrigerant circuit may become greater than a temperature of compressor 100. Moreover, the pressure Ps in suction chamber 8 may become greater than the pressure Pc in crank chamber Ps, and a temperature of refrigerant in the evaporator or the condenser may become greater than a saturated temperature of the refrigerant. In this condition, the discharge path is closed by valve element 14 g of check valve 14, and the refrigerant in suction chamber 8 does not flow into crank chamber 3 via the discharge path. Consequently, a liquid refrigerant does not accumulate in crank chamber 3, and a lubricant oil on a surface of swash plate 11 and pistons 13 is not washed away by the liquid refrigerant when the operation of compressor 100 begins. As a result, sufficient lubricant oil may be maintained between an exterior surface of swash plate 11 and an exterior surface of shoes 12 which are in sliding contact with each other, and sufficient lubricant oil may be maintained at the sliding portion between each piston 13 and their corresponding cylinder bores 1 a. Moreover, an amount of friction at the sliding portion between swash plate 13 and shoes 12, and an amount of friction at the sliding portion between each piston 13 and their corresponding cylinder bores 1 a, may not increase.
Referring to FIG. 3 another embodiment of the present invention is depicted. The features and advantages of this embodiment of the present invention are substantially similar to the features and advantages of the previously described embodiment of the present invention. Therefore, the features and advantages of the previously described embodiment of the present invention are not discussed further with respect to this embodiment of the present invention. In this embodiment, a check value [0024] 24 may have a pillar shape and may be positioned within center bore 1 b. Check valve 24 may have a penetration path 24 a. A first end of penetration path 24 a may open into crank chamber 3, and a second end of penetration path 24 a may open into suction chamber 8, such that crank chamber 3 and suction chamber 8 may be in fluid communication via penetration path 24. Check valve 24 may comprise a valve seat 24 a′, which may have a funnel shape. Valve seat 24 a′ may be positioned adjacent to the second end of penetration path 24 a. Check valve 24 also may comprise a valve element 24 b which may have a substantially circular or spherical shape. Valve element 24 may be positioned within penetration path 24 a, such that valve element 24 b may contact valve seat 24 a′. Valve element 24 b may comprise rubber, plastic, or the like. Moreover, an O-ring 24 c may seal a contact portion between check valve 24 and center bore 1 b.
When the pressure Pc in [0025] crank chamber 3 is greater than the pressure Ps in suction chamber 8, valve element 24 b may move away from valve seat 24 a′. Subsequently, a discharge path comprising center bore 1 b and a refrigerant path (not shown) opens. In contrast, when the pressure Pc in crank chamber 3 is less than or equal to the pressure Ps in suction chamber 8, valve element 24 b may contact valve seat 24 a′. Subsequently, the discharge path closes. In a modification of this embodiment or the previous embodiment, a check valve having a reed valve may be used instead of check valve 14 and 24, respectively.
Referring to FIG. 4, yet another embodiment of the present invention is depicted. The features and advantages of this embodiment of the present invention are substantially similar to the features and advantages of the previously described embodiments of the present invention. Therefore, the features and advantages of the previously described embodiments of the present invention are not discussed further with respect to this embodiment of the present invention. In this embodiment, a [0026] check valve 34 may be positioned within center bore 1 b. Check valve 34 may have a case 34 a, and case 34 a may have a cylindrical shape. A first portion of check vale 34 may be formed at a side of crank chamber 3, and a second portion of check valve 34 may be formed at a side of discharge chamber 9. Moreover, the diameter of the first portion may be greater than the diameter of the second portion. The first portion of check valve 34 may be positioned within center bore 1 b, and an O-ring 34 b may seal a contact portion between the first portion of check valve 34 and center bore 1 b. A bottom wall 34 h of check valve 34 may have a vent and may comprise a valve seat 34 c. A plurality of vents 34 d may be formed through a side wall 34 j of check valve 34 at the first portion of check valve 34. A cap 34 e may be elastically engaged with a flange formed at an open end 34 k of check valve 34, and a valve element 34 f may be positioned within case 34 a. A spring 34 g may be positioned between valve element 34 f and cap 34 e.
When the pressure Pc in [0027] crank chamber 3 is greater than pressure Ps in suction chamber 8, valve element 34 f moves away from valve seat 34 c. Subsequently, a discharge path comprising center bore 1 b and a refrigerant path (not shown) may open. As a result, the refrigerant in crank chamber 3 may be discharged into suction chamber 8 via the discharge path. Nevertheless, vents 34 d formed through the second portion of check valve 34 may remain open when the discharge path is open. In contrast, if the pressure Pc in crank chamber 3 is less than or equal to the pressure Ps in suction chamber 8, valve element 34 f contacts valve seat 34 c, and the discharge path is closed.
While the invention has been described in connection with preferred embodiments, it will be understood by those of ordinary skill in the art that other variations and modifications of the preferred embodiments described above may be made without departing from the scope of the invention. Other embodiments will be apparent to those of ordinary skill in the art from a consideration of the specification or practice of the invention disclosed herein. The specification and the described examples are considered as exemplary only, with the true scope and spirit of the invention indicated by the following claims. [0028]

Claims

What is claimed is:

1. A swash plate-type compressor comprising:

a housing having a cylinder block with a plurality of cylinder bores formed therethrough, wherein the cylinder block encloses a crank chamber, a suction chamber, and a discharge chamber;

a drive shaft rotatably supported by the housing;

a plurality of pistons each of which is positioned within a corresponding one of the cylinder bores;

a swash plate rotatably mounted on the drive shaft;

a discharge path formed between the crank chamber and the suction chamber; and

a check valve positioned within the discharge path, wherein the check valve is adapted to open the discharge path when a first pressure in the crank chamber is greater than a second pressure in the suction chamber, and to close the discharge path when the first pressure is less than or equal to the second pressure, such that a refrigerant within the crank chamber is discharged into the suction chamber via the discharge path when the first pressure is greater than the second pressure.

2. The swash plate-type compressor of claim 1, wherein the discharge path comprises a center bore formed in the cylinder block.

3. The compressor of claim 1, wherein the check valve comprises:

a case having a substantially cylindrical shape and a bottom portion, wherein at least one first opening is formed through the bottom portion,

a valve seat adapted to close an open end of the case, wherein a second opening is formed through the valve seat;

a valve element positioned within the case and fixed to a biasing member; and

a plurality of supports extending from the bottom portion of the case.

4. The compressor of claim 1, wherein the check valve comprises:

a penetration path formed through the check valve;

a valve seat having a substantially funnel-like shape and formed at an end of the penetration path; and

a valve element adapted to be received by the valve seat.

5. The compressor of claim 1, wherein the check valve comprises:

a case having a substantially cylindrical shape and a bottom portion, wherein a first opening is formed through the bottom portion and at least one second opening is formed through a side wall of the case, and wherein there is a clearance between the side wall and an inner surface of the discharge path;

a cap adapted to close an opening of the case; and

a valve element positioned within the case and fixed to a biasing member.