Compressor

Abstract

A swash plate compressor has a boss (178, 179) on an inner face (175, 176) of a bridge (174) of its piston (170) that contacts only an outer face (163, 164) of a swash plate (160) between edges (166, 167) to eliminate wear at the edges and thereby increase the life of the compressor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application Serial No. 17 / 832,238, filed on June 3, 2022, entitled “Compressor,” the contents of which are expressly incorporated herein by reference. Technical Field

[0003] The present invention relates to compressors, and more particularly to swash plate type compressors. Background Art

[0004] Refrigeration systems involving a fluid that changes from a liquid to a vapor (a phase change commonly referred to as evaporation) and back to a liquid again (a phase change commonly referred to as condensation) are common in motor vehicles, buildings, appliances, and industrial operations. When the housing being cooled is occupied by people, the refrigeration system is often referred to as an air conditioner.

[0005] The refrigeration system is characterized by two heat exchangers, a compressor, an expansion valve, and a refrigerant fluid. The compressor is arbitrarily selected as the starting point, and the fluid enters the compressor in the form of a low-pressure and low-temperature vapor. The vapor is compressed and leaves the compressor in the form of a high-pressure and high-temperature vapor. The vapor then passes through the first heat exchanger (called the condenser and is located in the surrounding environment). The vapor releases heat to the surrounding environment and condenses into a liquid. The liquid then passes through the expansion valve, where the pressure and temperature are reduced. The cold low-pressure liquid then passes through the second heat exchanger (called the evaporator and is located in the shell to be cooled). The liquid receives heat from the shell and evaporates into a low-pressure and low-temperature vapor. The vapor then returns to the compressor to complete and restart the cycle.

[0006] A variety of compressors are used in refrigeration systems. One type of compressor is known as a swash plate compressor. A conventional swash plate compressor 10 is shown in FIGS. 1 to 4. The compressor includes a block 11 having an inlet 12, an outlet 13, and a plurality of cylinders 14. As shown, the inlet and outlet are usually part of a separate head that is bolted to the portion of the block containing the cylinders. A rotating drive shaft 15 includes a swash plate 16. The swash plate is tilted (at an oblique angle) relative to the drive shaft. The swash plate engages five pistons 17 located in the cylinders. Each piston includes a solid bridge portion and a complementary empty recess portion extending between two complete cylindrical ends of the piston. The swash plate extends into the recess and causes the reciprocating motion of the piston when the swash plate and the drive shaft rotate. A spherical joint including a ball 18 is positioned between each side of the piston and each side of the swash plate, and the ball is held between the recess in the shoe 19 and the piston. The drive shaft, the swash plate, one piston, and the spherical joint are shown in their operating configuration in FIG. 3, and other components are omitted for clarity. These components are shown in an exploded view in FIG. 4 .

[0007] Swash plate compressors are used in many different types of refrigeration systems and are particularly preferred for use in motor vehicle refrigeration systems for several reasons. The compressors are compact and typically have a displacement of about 50 to 800 cubic centimeters. Unless otherwise indicated, the term "about" is used herein to refer to ±25% of the measured value or other property mentioned. The compressors also have relatively few moving parts. The compressors also deliver a relatively constant flow of compressed fluid because a volume of compressed fluid from each cylinder is delivered to the compressor outlet with each rotation of the drive shaft.

[0008] As the swash plate rotates, the pistons reciprocate and also tend to rotate slightly. The rotation of the pistons is limited by the contact between the bridge of the pistons and the outer face of the swash plate. Contact also occurs between the ball joints and the front and rear faces of the swash plate. Over time, these contact areas cause wear of these components and can eventually lead to failure of the compressor.

[0009] Therefore, there is a need for an improved swash plate compressor having an increased lifespan. Summary of the invention

[0010] A general object of the present invention is to provide an improved swash plate type compressor. A more specific object is to provide a swash plate type compressor having a longer service life.

[0011] We have invented an improved swash plate type compressor. The compressor comprises four main components: (a) a block; (b) a rotating drive shaft; (c) a swash plate; and (d) a plurality of reciprocating pistons. The first three components are conventional.

[0012] The block has: (i) a block inlet for receiving a fluid at a first pressure; (ii) a block outlet for discharging a fluid at a higher pressure; (iii) a central recess for receiving a drive shaft and defining an axis; and (iv) a plurality of hollow cylinders arranged around the central recess, each cylinder having an axis parallel to the axis of the central recess, each cylinder having an inlet connected to the block inlet and an outlet connected to the block outlet.

[0013] The axis of the rotary drive shaft in the central recess of the block is coaxial with the axis of the central recess.

[0014] The swash plate is attached to the drive shaft. The swash plate is inclined relative to the drive shaft and has: (i) a front face defining a front plane, (ii) a rear face defining a rear plane, the rear plane being parallel to the front plane of the front face; and (iii) an outer face extending between the front face and the rear face and forming a front edge where the outer face intersects the front face and forming a rear edge where the outer face intersects the rear face, the outer face being parallel to the axis of the drive shaft.

[0015] The pistons reciprocate in the cylinders as the swash plate rotates. Each piston has a cylindrical end and a central recess into which the swash plate extends. Each piston has a bridge piece connecting the ends and complementary to the recess. Each bridge piece has a front face overlapping the front face of the swash plate, a rear face overlapping the rear face of the swash plate, and an inner face having a boss that contacts only the outer face of the swash plate between the front edge and the rear edge throughout the rotation of the swash plate, so that no contact occurs between the piston and the front edge or the rear edge of the swash plate.

[0016] The compressor of the present invention has a longer service life. It is believed that the main reason for the increased service life is that the boss on the inner face of the piston bridge eliminates the contact between the piston and the front edge or the rear edge of the swash plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a perspective partial exploded view of a prior art swash plate type compressor.

[0018] FIG. 2 is a cross-sectional view of a prior art swash plate type compressor.

[0019] FIG. 3 is a perspective assembly diagram of components of a prior art swash plate type compressor.

[0020] FIG. 4 is an exploded perspective view of a prior art swash plate type compressor.

[0021] Figure 5 is a cross-sectional view of a preferred embodiment of a swash plate type compressor of the present invention.

[0022] Figure 6 It is a perspective assembly diagram of the components of the swash plate type compressor of the present invention.

[0023] Figure 7 It is a perspective exploded view of the swash plate type compressor of the present invention.

[0024] Figure 8 is a detailed view of one of the bosses of the swash plate type compressor of the present invention. DETAILED DESCRIPTION

[0025] 1.Compressor Overview

[0026] The present invention may be best understood by referring to the accompanying drawings. Figures 5 to 8A preferred embodiment of the compressor 100 of the present invention includes a block 110 having a fluid inlet 120, a fluid outlet 130, a plurality of cylinders 140, a rotating drive shaft 150 with an attached swash plate 160, and a plurality of pistons 170. Balls 180 and spacers 190 form a spherical joint between the swash plate and the pistons. All components of the compressor except the pistons are conventional. Each piston has an inner face with a boss that contacts the outer face of the swash plate only between the front and rear edges during the entire rotation of the swash plate. Thus, there is no contact between the piston and the front or rear edges of the swash plate.

[0027] The compressor of the present invention is suitable for use in any refrigeration system, but is particularly suitable for use in air conditioning systems in motor vehicles. The compressor of the present invention functions the same regardless of the direction of rotation of the drive shaft. The fluid inlet and fluid outlet remain the same regardless of the direction of rotation. The terms "front" and "rear" as used herein are arbitrarily selected, wherein the rear of the compressor is the end containing the fluid inlet and fluid outlet.

[0028] While not wishing to be bound by theory, it is believed that contact between the piston and the front and rear edges of the swash plate in a conventional swash plate compressor causes wear and unevenness at the outer edge of the swash plate. Figure 5 As can be seen in the upper piston of FIG. 1 , the ball joint extends outwardly over the edge of the swash plate during a portion of the swash plate's rotation. Therefore, any wear or unevenness on the outer edge of the swash plate caused by the piston results in wear and unevenness on the mating surface of the ball joint. Also, any wear or unevenness on the surface of the ball joint results in wear and unevenness on the front and rear faces of the swash plate. Therefore, eliminating contact between the piston and the front and rear edges of the swash plate reduces wear on the ball joint and the front and rear faces of the swash plate.

[0029] The absence of contact between the piston and the front or rear edge of the swash plate in the compressor of the present invention is believed to be the main reason for the increased life of the compressor.

[0030] 2. Blocks

[0031] The block 110 of the compressor is conventional. The block has an inlet 120 for receiving a fluid at a first pressure and an outlet 130 for discharging the fluid at a higher pressure. The inlet and outlet are typically part of a separate header. The fluid is typically a refrigerant. The block also has a central recess 135 for receiving a drive shaft. The central recess defines an axis. The block also has a plurality of hollow cylinders 140 arranged around the central recess. The preferred embodiment shown includes five cylinders. Compressors typically contain three to seven cylinders. Increasing the number of cylinders provides a more constant supply of pressurized fluid, but also increases the number of parts. The cylinders are typically radially equidistantly spaced. The axis of each cylinder is parallel to the axis of the central recess. Each cylinder has an inlet 141 that communicates with the block inlet. Each cylinder also has an outlet 142 that communicates with the block outlet. The portion of the block containing the cylinders is typically made of two or more parts connected together.

[0032] 3. Rotating drive shaft

[0033] The rotating drive shaft 150 of the compressor is conventional. The drive shaft rotates in the central recess of the block. One end 151 of the drive shaft is connected to a drive device. In a motor vehicle, the drive device is typically the engine or motor of the motor vehicle, which is connected to the drive shaft by gears, belts, etc.

[0034] 4. Swash plate

[0035] The swash plate 160 of the compressor is conventional. The swash plate is circular and is attached to the drive shaft at an oblique angle so that the swash plate is inclined relative to the drive shaft. The swash plate generally includes a mounting ring 161 portion and a plate portion 162. The swash plate has a rear face 163 defining a rear plane and a front face 164 defining a front plane. The rear plane and the front plane are parallel to each other. The angle formed by these faces with the drive shaft varies around the circumference of the drive shaft. The angle formed by the front face with the drive shaft and the angle formed by the rear face with the drive shaft are complementary because their measurements add up to 180 degrees at any point around the circumference of the drive shaft. The angle generally varies from an acute angle of about 10 to 30 degrees to an obtuse angle of about 150 to 170 degrees. The swash plate also has an outer face 165 extending between the front face and the rear face. The outer face is parallel to the axis of the drive shaft. The outer face has a rear edge 166 where it intersects the rear face and a front edge 167 where it intersects the front face.

[0036] 5. Piston

[0037] In addition to the boss, the piston 170 of the compressor is conventional. Each piston is usually cylindrical and fits tightly in the cylinder. Each piston has cylindrical ends 171, 172, and the ends have small cuts to accommodate (avoid contact) the swash plate mounting ring. Each piston has a recess 173 and a bridge 174, the swash plate extends into the recess, and the bridge connects the two cylindrical ends of the piston. The recess and the bridge together form an imaginary complete cylinder extending between the two cylindrical ends of the piston and connecting the two cylindrical ends of the piston. Therefore, the empty recess and the solid bridge are complementary. The bridge has a rear face 175 that overlaps with the rear face of the swash plate. The bridge also has a front face 176 that overlaps with the front face of the swash plate. As explained below, the front face of the bridge and the swash plate and the rear face of the bridge and the swash plate are usually not in direct contact with each other. Instead, a ball joint is usually between the faces to facilitate movement, reduce friction and distribute wear. When the ball joint is inserted, the front and rear faces of the piston bridge typically contain recesses (also called sockets) to retain the ball joint.

[0038] The bridge also has an inner face 177 that contacts the outer face of the swash plate. The inner face of the bridge of the preferred embodiment has two bosses 178, 179 that are raised above the surface. These bosses are the only points of contact between the inner face of the bridge and the outer face of the swash plate. Furthermore, these bosses only contact the outer face of the swash plate between the front and rear edges of the swash plate. Over time, the contact between the bosses and the outer face of the swash plate creates a wear pattern on the outer face. The wear pattern 168 is Figure 7 Shown in.

[0039] The size, shape and position of these bosses are selectable provided that they form the only contact between the inner face of the piston bridge and the outer face of the swash plate and provided that the bosses contact the outer face only between the front and rear edges, i.e. not the front or rear edges. The bosses are preferably positioned equidistant between the front and rear faces of the bridge. Figure 7 As best seen in FIG. 1 , each piston of the preferred embodiment includes two spaced-apart bosses. Figure 8 As best seen, the cross-sectional shape of the boss of the preferred embodiment is triangular, as this shape maximizes the cross-sectional area that can contact the outer face of the swash plate without contacting either edge. Other shapes are also suitable. The boss is typically cast or forged as part of the piston.

[0040] 6. Ball joint

[0041] The spherical joints are conventional and preferably consist of a ball 180 and a pad 190. Each pad has a flat side 191 that contacts the front or rear face of the swash plate. Each pad also has a recessed side 192 that holds a ball in contact with the front or rear face of the piston bridge. The recess is also called a socket. Each piston has two spherical joints. One joint is between the front face of each piston bridge and the swash plate, and one joint is between the rear face of each piston bridge and the swash plate. The spherical joints facilitate movement between the piston and the swash plate with minimal friction. The replaceable spherical joint (not shown) is a hemispherical ball with a flat side. The rounded portion of the ball fits into the recess in the piston, and the flat side of the ball contacts the front or rear face of the swash plate.

[0042] 7. Operation

[0043] The operation of the compressor can now be considered in detail. The operation is generally conventional. The drive shaft and the swash plate rotate. As the swash plate rotates, it causes the piston to reciprocate. Each reciprocating motion receives a certain volume of refrigerant fluid, compresses it to a smaller volume, and then discharges it. During operation, the inner face of the piston contacts the outer face of the swash plate. The compressor of the present invention differs from the compressors of the prior art in that the contact between the inner face of the piston and the outer face of the swash plate occurs only between the front edge and the rear edge. In other words, the piston does not contact the front edge and the rear edge, and therefore does not cause wear on the edges. It has been found that eliminating the wear caused by the piston on the outer edge of the swash plate produces a cascading effect of additional benefits. Eliminating the wear caused by the piston reduces unevenness and wear on the outer edge. This in turn reduces unevenness and wear on the flat face of the ball joint, and this in turn reduces unevenness and wear on the front and rear faces of the swash plate.

[0044] 8. Advantages

[0045] The swash plate compressor of the present invention has the advantage of eliminating contact between the piston and the outer edge of the outer face of the swash plate compared to existing swash plate compressors. This eliminates piston-induced wear on the outer edge. It has been found that eliminating piston-induced wear on the outer edge also reduces uneven wear on the ball joints, which in turn reduces uneven wear on the front and rear faces of the swash plate. Reducing wear on these components increases the life of the compressor.

[0046] Although the compressor of the present invention is generally manufactured and sold as a complete unit, the piston with the boss may replace a conventional piston in an existing conventional compressor.

Claims

1. A compressor, comprising: (a) a block having: (i) a block inlet for receiving a fluid at a first pressure; (ii) a block outlet for discharging fluid at a higher pressure; (iii) a central recess defining an axis; and (iv) a plurality of hollow cylinders arranged about the central recess, each cylinder having an axis parallel to the axis of the central recess, each cylinder having an inlet communicating with the block inlet and an outlet communicating with the block outlet; (b) a rotation drive shaft, the rotation drive shaft being located in the central recess, the axis of the rotation drive shaft being coaxial with the axis of the central recess; (c) a swash plate attached to the rotary drive shaft, the swash plate being inclined relative to the rotary drive shaft and having: (i) a front face defining a front plane, (ii) a rear face defining a rear plane, the rear plane being parallel to the front plane of the front face; (iii) an outer face extending between the front face and the rear face and forming a front edge where the outer face intersects the front face and a rear edge where the outer face intersects the rear face, the outer face being parallel to the axis of the rotary drive shaft; as well as (d) a plurality of reciprocating pistons, one reciprocating piston in each hollow cylinder, each piston reciprocating in the cylinder as the swash plate rotates, each piston having a cylindrical end and a central recess into which the swash plate extends, each piston having a bridge member connecting the cylindrical end and complementary to the recess, each bridge member having a front face overlapping the front face of the swash plate, a rear face overlapping the rear face of the swash plate, and an inner face having at least one boss, the at least one boss contacting only the outer face of the swash plate between the front edge and the rear edge throughout the rotation of the swash plate so that no contact occurs between the piston and the front edge or the rear edge of the swash plate.

2. The compressor of claim 1, further comprising a spherical joint between the front face of each piston bridge and the front face of the swash plate and a spherical joint between the rear face of each piston bridge and the rear face of the swash plate.

3. The compressor according to claim 2, wherein: Each piston has two bosses on its inner surface.

4. The compressor according to claim 3, wherein: The bosses on the interior face of each piston bridge are located equidistantly between the front and rear faces of the bridge.

5. The compressor according to claim 4, wherein: The boss on the inner face of each piston bridge is triangular in cross section.

6. A compressor comprising: (a) a block having: (i) a block inlet for receiving a fluid at a first pressure; (ii) a block outlet for discharging a fluid at a second pressure, the second pressure being greater than the first pressure; (iii) a central recess defining an axis; and (iv) a plurality of hollow cylinders arranged about the central recess, each cylinder having an axis parallel to the axis of the central recess, each cylinder having an inlet communicating with the block inlet and an outlet communicating with the block outlet; (b) a drive shaft, the drive shaft being adapted to rotate in the central recess, the axis of the drive shaft being coaxial with the axis of the central recess; (c) a swash plate adapted for attachment to the drive shaft for rotation, the swash plate being inclined relative to the drive shaft and having: (i) a front face defining a front plane, (ii) a rear face defining a rear plane, the rear plane being parallel to the front plane of the front face; (iii) an outer face extending between the front face and the rear face and forming a front edge where the outer face intersects the front face and a rear edge where the outer face intersects the rear face, the outer face being parallel to the axis of the drive shaft; as well as (d) a plurality of pistons adapted for reciprocating motion, one piston in each hollow cylinder, each piston adapted for reciprocating motion in each respective cylinder as the swash plate rotates, each piston having a cylindrical end and a central recess into which the swash plate extends, each piston having a bridge connecting the cylindrical ends and complementary to the recess, each bridge having a front face overlapping the front face of the swash plate, a rear face overlapping the rear face of the swash plate, and an inner face having at least one boss, the at least one boss contacting the outer face of the swash plate only between the front edge and the rear edge throughout rotation of the swash plate so that no contact occurs between the piston and the front edge or the rear edge of the swash plate.

7. The compressor of claim 6, further comprising a ball joint between the front face of each piston bridge and the front face of the swash plate and a ball joint between the rear face of each piston bridge and the rear face of the swash plate.

8. The compressor according to claim 7, wherein: Each piston bridge has two bosses on its inner surface.

9. The compressor according to claim 8, wherein: The bosses on the interior face of each piston bridge are located equidistantly between the front and rear faces of the bridge.

10. The compressor according to claim 9, wherein: The boss on the inner face of each piston bridge is triangular in cross section.

11. A piston for a swash plate type compressor, the swash plate having a front face, a rear face and an outer face, the outer face extending between the front face and the rear face and forming a front edge where the outer face intersects the front face, and forming a rear edge where the outer face intersects the rear face, the piston having a cylindrical end and a central recess, the swash plate extending into the central recess, each piston having a bridge piece complementary to the recess and connecting the cylindrical end, each bridge piece having a front face overlapping the front face of the swash plate, a rear face overlapping the rear face of the swash plate, and an inner face having at least one boss, the at least one boss only contacting the outer face of the swash plate between the front edge and the rear edge during the entire rotation of the swash plate, so that no contact occurs between the piston and the front edge or the rear edge of the swash plate.

12. The piston according to claim 11, wherein The front face and the rear face of the piston include ball sockets for receiving ball joints.

13. The piston according to claim 12, wherein: The inner surface of the bridge of the piston has two bosses.

14. The piston according to claim 13, wherein: The two bosses are equidistantly located between the front face and the rear face of the bridge.

15. The piston according to claim 14, wherein The cross section of the boss is triangular.

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