1. Field of the Invention
The invention relates to a compressor, and, in particular, to a compressor having improved thermal handling characteristics.
2. Description of the Related Art
A compressor receives a supply of fluid, such as a liquid or gas, at a first pressure and increases the pressure of the fluid by forcing a given quantity of the received fluid from a first volume into a smaller second volume using a piston assembly. Some compressors have a reciprocating piston that reciprocates within the cylinder to compress the fluid. The pistons may be connected to a crank shaft housed in a crankcase. The crankshaft may be operated by a motor housed in a motor housing. A typical piston assembly includes a cup seal to provide a seal between the pressurized and non-pressurized sides of the piston. The cup seal flexes during movement of the piston within the cylinder and the frictional engagement creates wear along the cup seal. The pressurization of gas on the pressurized side of the piston, the frictional engagement of the cup seal with the cylinder, and/or other operating conditions generate heat to which the cup seal is exposed. This heat further hastens failure of the flexible cup seal, thus limiting the life of the compressor.
In some compressors, heat may be dissipated from the cup seal using a crankcase that is directly coupled to the cylinder. Because of its mass, the crankcase may be intended to function as a heat sink to conduct the heat from the cylinder and the cup seal. Subsequently, a fan may provide air convection to dissipate the heat away from the crankcase.
However, in compressors where the motor housing is directly coupled to the crankcase, heat may be simultaneously conducted from the motor to the crankcase when heat is conducted from the cup seal and the cylinder to the crankcase. This is problematic when the thermal heat from the motor exceeds the heat being generated at or within the cylinder. In such situations, the heat from the motor may be indirectly conducted to the cylinder and the cup seal, thus ultimately increasing the heat on the cylinder and cup seal rather than decreasing it. Accordingly, further steps must be taken to remove heat from the cylinder/crankcase/motor housing system. For example, a larger fan may be used to provide higher CFM (cubic feet per minute) of air to convect the heat However, this may cause the device that includes such compressor and fan to be larger and bulkier. Alternatively or additionally, a larger crankcase may be used. However, this may cause the compressor to be bulkier, more expensive to manufacture, and inefficient.
Accordingly, it is an object of the present invention to provide a compressor assembly that overcomes the shortcomings of conventional compressor assembly. This object is achieved according to one embodiment of the present invention by providing a compressor assembly configured to increase pressure of a fluid that includes a cylinder forming a space for compressing the fluid and a piston configured to reciprocate in the cylinder so as to compress the fluid. The compressor assembly also includes a crank shaft configured to drive the piston and a crank shaft housing that is operatively connected to the cylinder and configured to house the crank shaft. A motor operatively is connected to the crank shaft and is configured to drive the crank shaft. The compressor assembly further includes a motor housing operatively connected to the crank shaft housing and configured to house the motor. A thermal insulator is disposed between the motor housing and the crank shaft housing to enhance thermal insulation between the motor housing and the crank shaft housing.
Another aspect of the invention relates to a method of assembling a compressor assembly that is configured to increase pressure of a fluid. The method includes obtaining a compressor assembly. The compressor assembly includes a cylinder having space for compressing the fluid. The compressor assembly also includes a piston, wherein the piston is configured to reciprocate in the cylinder so as to compress the fluid. The compressor assembly further includes a crank shaft that is configured to drive the piston and a crank shaft housing. The crank shaft housing houses the crank shaft and is connected to the cylinder. The compressor assembly further includes a motor that is configured to drive the crank shaft and a motor housing configured to house the motor in the motor housing. The method further includes coupling the motor housing to the crank shaft housing with a thermal insulator disposed therebetween to enhance thermal insulation between the motor housing and the crank shaft housing.
Another aspect of the invention relates to a compressor assembly configured to increase pressure of a fluid. The compressor assembly includes a cylinder coated with anodized metal material, the cylindrical cylinder having a mating portion and a main portion. The compressor assembly also includes a piston configured to reciprocate in the cylinder so as to compress the fluid and a crank shaft configured to drive the piston. A crank shaft housing is operatively connected to the cylinder and is configured to house the crank shaft. The compressor assembly also includes a motor operatively connected to the crank shaft and configured to drive the crank shaft. The mating portion of the cylindrical cylinder contacts the crank shaft housing. The anodized metal material of the mating portion is decreased or removed to facilitate thermal conduction between the cylinder and the crank shaft housing at the mating portion.
These and other objects, features, and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. In one embodiment of the invention, the structural components illustrated herein are drawn to scale. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not a limitation of the invention. In addition, it should be appreciated that structural features shown or described in any one embodiment herein can be used in other embodiments as well. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.
a is a cross sectional detailed view of the insulator ring disposed between a crankcase and a motor housing of the compressor in accordance with an embodiment;
b is a cross sectional detailed view of the insulator ring disposed between a crankcase and a motor housing of the compressor in accordance with another embodiment;
a is a cross sectional view of the insulator ring in accordance with an embodiment; and
b is a cross sectional view of the insulator ring in accordance with another embodiment.
As used herein, the singular form of “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. As used herein, the statement that two or more parts or components are “coupled” shall mean that the parts are joined or operate together either directly or indirectly, i.e., through one or more intermediate parts or components, so long as a link occurs. As used herein, “directly coupled” means that two elements are directly in contact with each other. As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other.
As used herein, the word “unitary” means a component is created as a single piece or unit. That is, a component that includes pieces that are created separately and then coupled together as a unit is not a “unitary” component or body. As employed herein, the statement that two or more parts or components “engage” one another shall mean that the parts exert a force against one another either directly or through one or more intermediate parts or components. As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality).
Directional phrases used herein, such as, for example and without limitation, top, bottom, left, right, upper, lower, front, back, and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.
In one embodiment, compressor assembly 10 has a tandem arrangement with two cylinders 12a, 12b, each having a piston 14a, 14b received therein. A motor shaft 16 connects the motor 20 to crankshafts 72, which are each connected to one of the two pistons 14a, 14b, so that the movement of the pistons 14a, 14b oppose each other. However, this embodiment is not intended to be limiting, and it is contemplated that the compressor assembly 10 may have other arrangements and numbers of cylinders 12a, 12b. For example, compressor assembly 10 may be of single or dual acting designs. Compressor assembly 10 may also include more than two cylinders.
In the embodiment shown in
In the illustrated embodiment, cylinders 12a, 12b are directly coupled to crankcases 18a, 18b. Each cylinder 12a, 12b may include a main portion 15 (see
Referring back to
As shown in
As shown in
In this embodiment, an input valve 52 enables fluid to be drawn through intake port 34 to the first interior space 50 when pistons 14a, 14b tilt within the cylinders 12a, 12b. An output valve 51 may be provided in the middle portion 48 to enable fluids to travel through first interior space 50 to exhaust port 42. Input valve 52 may be constructed and arranged such that input valve 52 allows air through only when pistons 14a, 14b are moving downwards. Output valve 51 may be constructed and arranged such that output valve 51 allows air through only when pistons 14a, 14b are moving upwards. Cylinder 12b may have a similar configuration as cylinder 12a.
As shown in
As mentioned above, cup seal 60 is configured to provide a seal between the pressurized and non-pressurized sides of the pistons 14a, 14b. That is, cup seal 60 may have an outward bias relative to head portion 54 such that it compressively engages inner walls 13a, 13b of cylinders 12a, 12b, respectively, throughout the pistons' 14a, 14b strokes, thereby preventing fluid from escaping from the upper interior space 50. Cup seal 60 may adopt an upwardly flexed position with respect to inner surface 11 of cylinders 12a, 12b. A screw 62 may be used to secure cap 53 to head portion 54 of piston 14a, 14b, thereby also retaining cup seal 60 within groove 58.
In the illustrated embodiment, rod portion 56 of pistons 14a, 14b has a lower end 68 with a bearing 70. Each bearing 70 has a center 71 that is configured to receive a portion of the crank shaft 72. Eccentric crank shafts 72 are connected to motor shaft 16 such that the axis defined by the motor shaft is offset from the axis defined by center 71 of bearings 70. Thus, motor shaft 16 and pistons 14a, 14b are configured to be eccentric. As such, as the motor shaft rotates crankshafts 72, pistons 14a, 14b, which ride on the bearings 70, reciprocates upwardly and downwardly within the cylinders 12a, 12b. This configuration enables pistons 14a, 14b to tilt relative to cylinders 12a, 12b at all positions (except when pistons 14a, 14b are at the top most and bottom most positions) due to the eccentricity of crank shafts 72. It is contemplated the crank shafts do not need to be eccentric and may have other configurations or arrangements. As an exemplary reference, piston 14a shown in
As mentioned above, the movement of pistons 14a, 14b within cylinders 12a, 12b causes heat to increase on cup seals 60 and cylinders 12a, 12b due to the frictional engagement between the cup seals 60 and inner surface 11 of cylinders 12a, 12b, and/or due to the compression of fluid. Crankcases 18a, 18b may be used as a heat sink to conduct the heat from cylinders 12a, 12b and cup seals 60. A cooling fan (not shown) may be provided to generate cooling current for convecting heat away from compressor assembly 10.
In the embodiment shown in
Thermal insulators 24a, 24b may have any configuration that enables thermal insulators 24a, 24b to enhance thermal isolation between crankcases 18a and motor housing 22. The size and thickness of thermal insulators 24a, 24b may depend on the configuration and arrangement of crankcases 18a, 18b and motor housing 22. For example, as mentioned above and as shown in
Referring back to the embodiment shown in
As shown in
In the embodiment shown in
Thermal insulator 24a may be configured to be disposed between crankcase 18a and motor housing 22 in a similar manner. Thermal insulator 24a may also be configured to contact motor housing 22 in a similar manner as either of the two embodiments of thermal insulator 24b shown in
Thermal insulators 24a, 24b may be manufactured and/or assembled with compressor assembly 10. In some embodiments, thermal insulators 24a, 24b may be retrofit into existing compressor assemblies 10. That is, compressor assemblies 10 may already be manufactured and assembled without thermal insulators 24a, 24b. In such embodiments, thermal insulators 24a, 24b may be added to compressor assemblies 10 at the points of contact between crankcases 18a, 18b and motor housing 22 to enhance thermal isolation therebetween.
Thermal insulators 24a, 24b may be made of stainless steel, such as those having a conductivity of about 15 W/(m*K) (Watts per meter-Kelvin). The stainless steel may have wear resistant properties, low creep, and may be constructed at a low cost. Other materials may also be used, such as, just for example, glass filed nylon (e.g., 30% glass filled Nylon 66 having a conductivity of 0.27 W/(m*K)), Telfon®, ceramics having properties of low creep and low conductivity, plastics having low thermal conductivity and low creep, and/or other materials with low thermal conductivity and low creep. Crankcases 18a, 18b may be made of aluminum, such as those having a conductivity between 100 and 200 W/(m*K)) or other materials. Motor housing 22 may be made of aluminum or other materials. Cylinders 12a, 12b may also be made of aluminum, or may be made of other materials. In one embodiment, cylinders 12a, 12b are made of aluminum having a grade of AL6061 with a conductivity of about 170 W/(m*K). The cylinders may have an anodized coating to improve the properties thereof, such as to increase its corrosion resistance and wear resistance. However, the anodized coating in such embodiments may cause the conductivity of cylinders 12a, 12b to decrease. In some embodiments, the conductivity may be decreased to, just for example, 30-35 W/(m*K). As such, the effectiveness of the heat dissipation from the cylinders 12a, 12b to crankcases 18a, 18b are also decreased.
The lowered conductivity may be problematic when crankcases 18a, 18b function as heat sinks for cylinders 12a, 12b. That is, lowered conductivity due to anodized coatings may impede the flow to crankcases 18a, 18b of heat generated in cylinders 12a, 12b by the frictional engagement between cup seal 60 and inner surface 11 of cylinders 12a, 12b and/or by the compression of fluids.
The following description of crankcase 18a and cylinder 12a may also be applicable to crankcase 18b and cylinder 12b. In the embodiment shown in
To combat this, in the embodiment of
Mating portion 17 may be configured to include any portion of cylinder 12a that contacts crankcase 18a. Mating portion 17 may be the portion of cylinder 12a that contacts or mates with crankcase 18a, or may optionally be larger such that only a portion of mating portion 17 contacts crankcase 18a. Main portion 15 of cylinder 12a may be the rest of cylinder 12a (or any portion of cylinder 12a that is not mating portion 17). Cylinder 12b may have a similar configuration as cylinder 12a.
Compressor assembly 10 may operate as follows in accordance with an embodiment. In one embodiment, motor 20 rotates crankshaft 72 via motor shaft 16 to operate piston 14a. As piston 14a travels from the top most position to the tilted position (not shown), the suction created within its associated cylinder 12a causes fluid to travel from the chamber 36 into its associated cylinder 12a through input valve 52. Cup seal 60 may adopt an upwardly flexed position where it engages interior surface 11 of cylinder 12a when piston 14a is moving downwards towards the bottom most position.
After piston 14a has reached the bottom most position, the piston then moves upwards to a tilted position, thereby compressing the fluid in its associated cylinder 12a. Cup seal 60 may optionally adopt a downwardly flexed position where it engages with inner surface 11 of cylinder 12a when piston 14a is moving upwards. The upward motion of piston 14a, 14b causes output valve 51 to open, thereby allowing the fluid to travel to internal exhaust chamber 38 and to exhaust port 42. The other piston 14b functions in an opposing way. Thus, when piston 14a moves from the down most position towards the top most position, piston 14b moves from the top most position to the down most position. During the movement of pistons 14a, 14b within cylinders 12a, 12b, the heat generated by the frictional engagement between cup seals 60 and inner surfaces 11 of cylinders 12a, 12b and/or by the compression of fluid is conducted from cylinders 12a, 12b to crankcases 18a, 18b. Heat is conducted from cylinders 12a, 12b to crankcases 18a, 18b via mating portions 17 of the cylinders that have been ground to decrease the anodized coatings thereon. In addition, as motor 20 rotates crankshaft 72 to move pistons 14a, 14b, heat is generated by motor 20. Thermal insulators 24a, 24b thermally isolate motor housing 22 to decrease the amount of heat conducted from motor housing 22 to crankcases 18a, 18b. Thus, heat dissipation may be enhanced in compressor assembly 10 by the use of thermal insulators 24a, 24b and/or by grounding portions of cylinders 12a, 12b (i.e., mating portion 17) to decrease or remove the anodized coating thereon.
Although a compressor assembly 10 is described above, it is contemplated thermal insulator 60 may be used with other devices such as, just for example, gear motors, pumps, and blowers, or any device that has a motor that is mechanically coupled to other components. By thermally isolating the motor from other components, the performance and efficiency of the devices would be improved. Furthermore, the thermal insulators may also help reduce the size of the fan required to cool the device, thus reducing the costs associated with the device.
Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.
This patent application claims the priority benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/377,607 filed on Aug. 27, 2010, the contents of which are herein incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB11/53679 | 8/22/2011 | WO | 00 | 2/18/2013 |
Number | Date | Country | |
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61377607 | Aug 2010 | US |