Title:
Swash CAM type Refrigeration Compressors with Spherical, Elliptical,
Cylindrical rolling Shoes for all automotive air-conditioning applications
Field of Invention:
This invention relates to the design method and system of an innovative Swash CAM type Refrigeration Compressors with Spherical or Elliptical, Cylindrical rolling Shoes which have the innovative features of CAM profile with Spherical or Elliptical, Cylindrical raceway and with Spherical or Elliptical, Cylindrical rolling Shoes and single or doubled headed Piston with Spherical or Elliptical, Cylindrical pocket for the Spherical or Elliptical, Cylindrical rolling shoes for the cooling capacity range from 1 kW to 50 kW which can be used for all Air Conditioning applications like Car air-conditioning, Bus air-conditioning, Rail coaches Air-Conditioning and truck refrigeration units for transport of refrigerated goods.
Background of the invention:
General Scenario:
Compressors are used for sucking the low pressure super heated (any type of refrigerants, HFC (Hydrofluoro Carbon) , HFO (hydrofluoro-olefin), NH3, C02 and etc..) refrigerant gas from Evaporator (through Internal Heat Exchanger (IHX) if it is connected in the circuit), compressing to high pressure and discharging the compressed refrigerant gas at high temperature to Condenser for de-superheating, Condensing and sub-cooling the refrigerant medium in the vapour compression Refrigeration systems used in the chemical industry, Process industry, Air Conditioning applications, Power generation units and many other applications. Though our disclosed invention put forward by the current patent application may find a number of other embodiments, we are presenting the invention through an embodiment especially applicable to the automotive Air Conditioning systems having Swash CAM type Refrigeration Compressors with with Spherical or Elliptical, Cylindrical rolling Shoe
for the applications like Car air-conditioning, Bus air-conditioning, Rail coaches Air-Conditioning and truck refrigeration units for transport of refrigerated goods. Automotive sector has been growing at a fast pace and due to tighter environment norms and steep competition the quest for efficiency increment, compactness, light weight and lower cost are increasing day by day.
Refrigerant Vapor Compression Refrigeration circuit:
The prime goal of the designers of automotive air conditioning systems is to minimize the power consumption of compressor by increasing the volumetric efficiency and also increasing the mechanical efficiency, which together are responsible for the higher COP to provide the rated cooling capacity of the system. The Piston compressor by principle having higher volumetric efficiency and mechanical efficiency at lower speeds compared to at higher speeds.
Problem Statement:
There exists a need of a high efficient compressor which must be compact, light weight and low cost to provide higher COP for the rated cooling capacity. The present invention addresses such a need. More particularly, the invention relates to devices and methods employing Swash CAM type Refrigeration Compressors with Spherical or Elliptical, Cylindrical rolling Shoes, have the innovative features of special CAM profile with Spherical or Elliptical, Cylindrical raceway and Spherical or Elliptical, Cylindrical rolling Shoe and single or doubled headed Piston with Spherical or Elliptical, Cylindrical pocket for the Spherical or Elliptical, Cylindrical rolling shoe to enhance COP of Overall system and multiple the cooling capacity without compromising the overall dimension of the compressor boundary in comparison with the Conventional Swash plate having conventional swash plate and hemi-spherical shoes.
Prior Art:
The U.S. Patent no. 1,409,057 dated Mar 7, 1922 by A.G.M. MICHELL disclosed the invention related to Mechanism for the Inter-conversion of Reciprocating and Rotary Motion in general, and specifically to double sided Piston and Swash plate of plain taper surface with Shoe having Spherical surface to mesh with Piston pocket and plain surface to mate with Swash plate.
The U.S. Patent no. 2,080,846 dated 18 May 1937 by H. ALFARO disclosed the invention related Internal Combustion Engine with single headed Pistons of opposed construction and driven by Cam for Aircraft application.
The U.S. Patent no. 2,237,989 dated 8 April 1941 by K.L. HERRMANN disclosed the invention related Internal Combustion Engine with Double headed Pistons and driven by Cam fixed to shaft for Aircraft application.
The U.S. Patent no. 6,779,494 B1 dated 24 Aug'2004 by Aswani et al. disclosed the invention related Balanced Barrel -CAM Internal Combustion Engine with single headed Pistons and driven by conjugate axial Cam with dual rolling followers.
The Indian Patent application No. 1475/DEL/2012 dated 14th May 2012, by Selvaraji Muthu et al: disclosed that Swash plate type Refrigeration Compressors with Convergent conical shape Pistons and matching Cylinder bores.
The Indian Patent application No. 1476/DEL/2012 dated 14th May 2012, by Selvaraji Muthu et al. disclosed that Swash plate type Refrigeration Compressors with Composite Pistons made up of composite materials partially using metallic materials (Aluminium, Cast-Iron, Steel) etc..) by casting, forging, machining and the rest with either of Non-metallic materials like PTFE, PEEK, PPS through injection molding process.
The Indian Patent application NO.1831/DEL/2012 dated 14th June 2012, by Selvaraji Muthu et al. disclosed that Swash plate type Refrigeration Compressors with double headed Labyrinth Pistons for Automotive Air-conditioning applications.
The Indian Patent application No. 1832/DEL/2012 dated 14th June 2012, by Selvaraji Muthu et al. disclosed that Swash plate type Refrigeration Compressors with Composite housings with ease of manufacturing for Automotive Air-conditioning applications.
(Table Removed)
The following text book and Conference paper have been referred.
(*1) Refrigeration Compressor by MIAO DAO PING WU YE ZHENG 2001 page no. 49 & 50 of 298, ISBN-13: 978-7111079231
(*2) Dynamics of the Swash Plate Mechanism, Below, J. F. and Miloslavich, D. A., (1984). International Compressor Engineering Conference. Paper 437. http://docs.lib.purdue.edu/icec/437
Disadvantages of prior art:-
1. Boundary volume of the compressor is high for the rated cooling capacity
. 2. Overall weight of the compressor is high for the rated cooling capacity
3. Cost is high due to bigger size and higher weight
4. Higher frictional power loss due to surface contact of Shoe, hence lower COP
5. Contributing to more global warming
SUMMARY OF THE INVENTION:
The Swash CAM type Refrigeration Compressors, having special CAM profile with Spherical or Elliptical, Cylindrical raceway and single or doubled headed Piston with Spherical or Elliptical, Cylindrical pocket for the Spherical or Elliptical, Cylindrical rolling shoes, shown in Figure-1 of 14 until Figure 14 of 14.
The Swash plate design is made with innovative features of Cam profile and spherical raceway.
(Formula Removed)
Whereas
n : No. of Cylinders in the Compressor
m : No. of Cycles per revolution (360 °)
D : Diameter of the Piston, cm
S : Stroke of the Piston , cm
D - Ranges from 2 cm to 5 cm
n - Ranges from 6 to 20 (inclusive of 2, 4, 6 , 8, 10, 12, 14, 16, 18 )
m - Ranges from 1 to 4 (1 is for conventional swash plate Compressor)
The Swash Cam Compressor converges to conventional Swash plate compressor with m=1 in terms of Swept volume as shown in the figure 10 of 18., whereas the advantage of replacing the rubbing or sliding motion of Shoe by pure rolling motion with the innovative feature of spherical raceway has resulted lower frictional power loss and hence higher mechanical efficiency and COP.
The higher the value of no. of cycles per revolution, the theoretical swept volume is get multiplied by that extent.
(Formula Removed)
Where
x : Instantaneous displacement of spherical Shoe in the Cam or Piston, cm
5 : Stroke of the Piston, cm
6 : Instantaneous angle of rotation of shaft
P : Angle by which half cycle is completed
p : Degree of Polynomial of Polynomial Cam
Cp : Constant Coefficients of Polynomial of Polynomial Cam
(Formula Removed)
M=1 , M=2 , M=3 , M=4, Figures 1 to 18 to Figures 18 of 18 to be referred. M=1 and Conventional Swash (profile Comparison)
Correlations for Displacement by Conventional Swash plate, from the references cited
(Formula Removed)
Where
x : Instantaneous displacement of swash plate or Piston
PCD : Pitch Circle Diameter, cm
6 : Instantaneous angle of rotation of shaft
a : Swash plate taper angle
(*1) Refrigeration Compressor by MIAO DAO PING WU YE ZHENG 2001 page no. 49 & 50 of 298, ISBN-13: 978-7111079231 (Chinese Book)
(*2) Dynamics of the Swash Plate Mechanism, Below, J. F. and Miloslavich, D. A., (1984). International Compressor Engineering Conference. Paper 437 .Purdue University http://docs.lib.purdue.edu/icec/437
BRIEF DESCRIPTION OF THE DRAWINGS
For a detailed description of the preferred embodiments of the invention, reference will
now be made to the accompanying drawings in which:
Figure 1 of 18 - CAM Profile for parameter "m=r
Figure 2 of 18 - CAM Profile with Spherical raceway for the Spherical rolling Shoe for
parameter "m=1"
Figure 3 of 18 - CAM Profile for parameter "m=2"
Figure 4 of 18 - CAM Profile for parameter "m=3"
Figure 5 of 18 - CAM Profile for parameter "m=4"
Figure 6 of 18 - Displacement of the Swash CAM Compressor with different Cam Profiles
Figure 7 of 18 - 3D Swash CAM , 7(a), 7(b), 7(c) & 7(d).
Figure 7 of 14 - Swash Cam with Spherical Rolling Shoe and Spherical Rolling
Raceway of Piston, front view
Figure 8 of 18 - Swash Cam with Spherical Rolling Shoe and Spherical Rolling Raceway of Piston, front view
Figure 9 of 18 - - Swash Cam with Spherical Rolling Shoe and Spherical Rolling Raceway of Piston, oblique view
Figure 10 of 18 - General Assembly of Swash CAM Compressor with spherical rolling shoe, sectional View with part shading
Figure 11 of 18 - General Assembly of Swash CAM Compressor with spherical rolling shoe, sectional View with hatching
Figure 12 of 18 - Swash CAM (profile with m=2) with rolling spherical Shoe, Showing Method of Piston sub-Assembly getting inserted in to the Swash CAM raceway. Figure 13 of 18 - Swash CAM (profile with m=2) with rolling spherical Shoe
Figure 14 of 18 - Swash CAM (profile with m=2) with rolling spherical Shoe, showing both side Shoes
Figure 15 of 18 - Swash CAM (profile with m=2) with rolling cylindrical Shoe, showing both side Shoes
Figure 16 of 18 - Double headed Piston with Cylindrical raceway for the rolling cylindrical Shoe
Figure 17 of 18 - Swash CAM (profile with m=2) with rolling cylindrical Shoes, showing both side Shoes with Piston Sub-assembly
Figure 18 of 18 - General Assembly of Swash CAM (profile with m=2) Compressor with rolling cylindrical Shoes, sectional View with hatching
DETAILED DESCRIPTION
1. According to one aspect of the invention, swash CAM compressor with multiple single or double headed pistons having the Spherical or Elliptical, Cylindrical raceway on Swash for Spherical or Elliptical, Cylindrical rolling shoes.
2. The compression load of Piston is transmitted to swash CAM through Spherical or Elliptical, Cylindrical shoes on either side of the swash CAM, shown in Figure-1 of 18 until Figure 18 of 18.
3. Swash CAM having Spherical or Elliptical, Cylindrical raceway to avoid rubbing/sliding motion by providing pure rolling motion, which in turn will have negligible friction, shown in Figure-8 of 18
4. Reed type of valves for Suction and Discharge of refrigerant gas in the Swash CAM Compressor, shown in Figure-10 of 18.
5. The Cylinder blocks having cylindrical bore or non-cylindrical bore for the matching Pistons are connected together by using Gaskets or O-rings.
6. The Rear and front side covers are connected together by using Gaskets or O-rings.
7. The front side cover has bore for oil seal assembly (Mechanical seal or Lip Seal type) and also has projection for assembling the Electro Magnetic Clutch parts.
8. Swash CAM with 2 identical thrust bearing of kind anti-friction roller or ball bearings on opposite sides of Swash CAM for transferring the bi-directional thrust loads to the housings.
9. The drive shaft is guided by either anti-friction type ball or roller bearings or bush bearings on both the sides of swash CAM.
10. The Swash CAM is made up of either by using Allow Steel, Cast Iron, Aluminium Alloy, or Composite Construction of these metallic materials with the non-metallic engineered plastics or polymers, such as PTFE, PEEK, PPS, etc...
11. The Composite construction of Swash CAM is made up of partially using composite metallic materials (Aluminium, Cast-Iron, Steel) etc...(by forging, machining, casting, molding)) and the rest with either of Non-metallic materials like PTFE, PEEK , PPS through injection molding process or entirely made up of
Non-metallic materials like PTFE, PEEK , PPS through injection molding process.

Claims
What is claimed is:
1. A swash CAM type Compressor for air conditioning applications in general
and automotive application in particular comprising of multiple double
headed Pistons, matching Cylindrical Bores, set of suction and discharge
valves, valve plate, drive end and non-drive end covers, the Swash CAM
integral with the input drive shaft, set of thrust bearings and radial bearings
for taking the axial and radial loads in addition to provide the axial and radial
constraints to the input shaft with negligible friction.
2. The Swash CAM is having Spherical or Elliptical, Cylindrical raceway for the
Spherical or Elliptical, Cylindrical rolling Shoe with CAM profile as per
Simple Harmonic form, mathematically defined as below.
(Formula Removed)
3. The Swash CAM is having Spherical or Elliptical, Cylindrical raceway for the
Spherical or Elliptical, Cylindrical rolling Shoe with CAM profile as per
Cycloidal form, mathematically defined as below.
(Formula Removed)
4. The Swash CAM is having Spherical or Elliptical, Cylindrical raceway for the
Spherical or Elliptical, Cylindrical rolling Shoe with CAM profile as per
Polynomial Curve form, mathematically defined as below.
(Formula Removed)
5. The above claimed CAM profiles for this application are only few examples,
whereas all the possible shapes, forms and profiles are also covered in this
embodiment for the application.
6. In this embodiment, the input parameter p used in the CAM profile
Mathematical form covered as above in points 1, 2, 3, & 4 is defined as
below.
(Formula Removed)
7. The different Swash CAM profiles have been shown in Figure 1 of 10 to
Figure 6 of 10.
8. Theoretical Swept volume of the Compressor is directly proportional to the
parameter "n" and the parameter "m, as shown in the following
mathematical expression.
(Formula Removed)
9. The parameter" m ", which is no. of cyclic operation of Piston per revolution
of Swash CAM covered in this embodiment are 1, 2 , 3 , 4 & 5.
10. The ranges of parameter "n" covered in this embodiment are 2, 4, 6, 8, 10,
12, 14, 16, 18&20.
11. The terminal swept volume as per the Swash plate profile defined as below is exactly achieved by the above listed different CAM profiles.
(Formula Removed)
12. As per this embodiment, Swash CAM compressor with Swash CAM profile
with m=2, will have twice of theoretical Displacement compared to the
conventional compressor under same boundary dimensions.
13. Similarly the Swash CAM profile with different value for the parameter "m",
will have higher displacement by "m" times compared to conventional
design.
14. The Swash CAM design disclosed in this embodiment is having the rolling action with the spherical Shoe, which is anti-friction by the concept.
15. The minimum wall thickness ("t") between cylinder bores and the Pitch Circle Diameter (PCD) of Cylinder bores are related by the following relation.
(Formula Removed)
16.The Swash CAM can be manufactured by Forging, Machining, Casting, Injection Molding, EDM (Electro Discharge Machining), Laser Cutting, etc...
17. The Material of construction of the Swash CAM either by using Allow Steel, Cast Iron, Aluminium Alloy, or Composite Construction of these metallic materials with the non-metallic engineered plastics or polymers, such as PTFE, PEEK, PPS, etc...
18. The Composite construction of Swash CAM is made up of partially using composite metallic materials (Aluminium, Cast-iron, Steel) etc...(by forging, machining, casting, molding)) and the rest with either of Non-metallic materials like PTFE, PEEK , PPS through injection molding process or entirely made up of Non-metallic materials like PTFE, PEEK , PPS through injection molding process by which the additional machining is completely avoided and made possible with 40% - 50% weight reduction and about 70% ~ 80% reduction in manufacturing time of compressors.
19.The non-metallic materials referred in the point no. 13 includes the variants of PTFE, PEEK and PPS with 10%, 20%, 30% of Glass Filled and 10%, 20%, 30% of carbon Filled grades.
20.The weight reduction stated in the point no. 18 (as above) would result to reduce the inertia force required for the rotation of swash CAM by the same factor, which in turn increases the overall mechanical efficiency.
21. The Swash CAM Spherical or Elliptical, Cylindrical Raceway surface is treated with Tin plating for 1 ~ 10 microns layer thickness
22. Alternatively, the Swash CAM Spherical or Elliptical, Cylindrical Raceway surface is treated with self solid lubricant cum anti-friction coating materials, such as PTFE, PEEK, PPS, MoS2, Graphite based coating materials for the layer thickness of 5 ~ 50 microns by one of the process of electrostatic spraying, electrostatic fluidized bed, conventional powder and liquid spraying, Dipping or immersion, Electro-Deposition ("E" coat), Electro-Static coatings methods.
23. The convergent conical shaped double ended Piston is disclosed in our Patent Application no. 1475/DEL/2012 dated 14Th May 2012.
24. The Composite Construction of Double ended Piston is disclosed in our Patent Application no. 1476/DEL/2012 dated 14Th May 2012.
25. The Non-metallic Material grades are disclosed in our Patent Application no. 1476/DEL/2012 dated 14Th May 2012.
26.The Double headed Labyrinth Piston is disclosed in our Patent Application
no. 1831/DEL/2012 dated 14Th June 2012. 27. The Composite Construction of housings of swash plate compressor is
disclosed in our Patent Application no. 1832/DEL/2012 dated 14Th June
2012.
28. The range of Piston nominal diameters covered in this embodiment are from 10 to 50mm in general and includes the specific Diameters namely 25, 28.5,29.5, 30.5, 32, 34, 36, 38, 40 , 42, 46, 50mm to name a few.
29. The range of ratio of length of Piston to Piston nominal diameter covered in this embodiment is from 1 to 5.
30. As per this embodiment, application of Swash CAM compressor includes the automotive air-conditioning (Car and Bus Segments) and refrigeration (Reefer trucks etc... ) with refrigerant types like HFC (Hydrofluoro Carbon), HFO (hydrofluoro-olefin), NH3, C02 and etc..) in general and specific to R134a , R1234yf, C02 Refrigerants.
Where
n : No. of Cylinders in the Compressor m : No. of Cycles per revolution (360 °) D : Diameter of the Piston, cm
S : Stroke of the Piston , cm
PCD : Pitch Circle Diameter of Cylinders, cm
x : Instantaneous displacement of spherical Shoe in the Cam or Piston
6 : Instantaneous angle of rotation of shaft
α : Swash plate taper angle
ß : Angle by which one cycle is completed
p : Degree of Polynomial of Polynomial Cam
Cp : Constant Coefficients of Polynomial of Polynomial Cam
PTFE PolyTetraFluoroEthylene
PEEK PolyEtherEtherKetone
PPS PolyPhenylene Sulfide