|Title of Invention||
A SPLIT VALVE PLATE FOR AN AIR COOLED COMPRESSOR
|Abstract||This invention relates to a split valve plate for an air cooled air compressor for a motor vehicle braking system. This is achieved by incorporation of split valve plate, which contains atmospheric air in between valve plate and valve plate cover. The air between valve plate and valve plate cover acts as insulator and prevents heat flow from high temperature top surface of valve plate in delivery cavity of cylinder head to bottom surface of valve plate exposed to cylinder bore and also prevents heat flow from cylinder bore to air in inlet cavity of cylinder head. This reduced heat transfer reduces the heating of air in cylinder bore and there by reduces delivery air temperature.|
The invention relates to air compressors and more especially it relates to a reciprocating air compressor.
Reciprocating compressors comprises a piston and cylinder arrangement with a cylinder head assembly over the cylinder. The cylinder head assembly is made of cylinder head, inlet valve and delivery valve and valve plate with inlet and delivery holes. The cylinder head has an inlet port opening to the inlet cavity and a delivery port opening into the delivery cavity. The inlet valve opens during induction stroke of the piston and the delivery valve opens during the delivery stroke of the piston. The air compressor intakes air at lower pressure through the inlet holes and compresses it to higher pressure and temperature through the delivery holes. The delivery cavity portion of the cylinder head is provided with extended surface for better heat extraction from the hot air.
Following are the undesired effects of high delivery air temperature in compressors of automotive air brake system
1. Increased carbon deposit formation from lubricating oil on valve plate surfaces and compressor cylinder head. This will reduce the inlet and delivery valve life,
2. Increases oil consumption
3. Long metal piping for cooling the air in the system before entry into down stream units.
Heating of intake air in compressor is takes place by three ways.
As the air travels into cylinder head inlet cavity and valve plate holes, it picks up heat from high temperature valve plate and cylinder head surfaces of inlet cavity. The heat transfer from valve plate and cylinder head surfaces to inlet air takes place by convection heat transfer.
As the air fills the cylinder bore during suction stroke, there will be heat flow from high temperature delivery cavity filled with hot air to air in cylinder bore through valve plate. The heat transfer from hot delivery air to valve plate takes place by convection. In valve plate heat transfer from top surface to bottom surface takes place by conduction. The heat transfer from valve plate surface to air in cylinder bore takes place by convection.
During compression according to thermodynamic principles, heat will be generated. The generated heat is a function of inlet air temperature, inlet air pressure and delivery air pressure and speed of compression.
The present invention is addressed at reducing the convective heat transfer from valve plate to inlet air in inlet cavity of the cylinder head and reducing the conductive heat transfer in valve plate from top surface to bottom surface.
Heat extraction from hot delivery air can be accomplished in three ways.
a. Extraction of heat from hot air to cylinder head and valve plate
surfaces by convective heat transfer.
b. Conduction of heat from respective hot air contact surfaces to
atmospheric air contacting surfaces.
c. Dissipation of heat from hot cylinder head and valve plate to
atmosphere by convective heat transfer.
Invention for better heat extraction from hot delivery air to cylinder head is claimed through another patent application 621/CHE/03 bearing the title "Cylinder head with improved cooling efficiency for air compressor for a motor vehicle braking system". The present invention is also addressed at improving extraction of heat from hot valve plate to atmosphere by introducing extended surface area in valve plate itself.
SUMMARY OF INVENTION
The inventors have made great effort to provide a system, which will meet the requirement of the industry and overcome the problem associated in the prior art.
To achieve the above object according to first aspect and feature of the present invention there is provided a system to improve cooling efficiency for air compressor for a motor vehicle braking system.
According to second aspect and feature of the invention in addition to the first feature the invention comprises a system, which is unique, rugged, efficient and economical.
At the outset of the description which follows it is to be understood that ensuring description only illustrate a particular form of this invention. However, such particular form is only an exemplary embodiment, and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and reading of the invention and not intended to be taken restrictively.
Accordingly the salient feature of the present invention is by splitting the valve plate into two and introducing air gap in between them. The air gap between valve plate and valve plate cover acts as an insulator and prevents heat flow across valve plate.
According to the present invention, the valve plate is made up of cast iron casting along with inlet and delivery holes for airflow into and out of cylinder bore. This valve plate is provided with air pockets in the areas other than outer edges of valve plate and air flow path. Another sheet metal valve plate cover with extended surfaces fastened over the cast iron valve plate. This forms the configuration of two metal surfaces sandwiched in between air packets.
In conventional valve plate configuration will be solid metal plate onto which inlet and delivery valves will be seating. Moreover there will not be any projection of valve plate surface beyond cylinder head to improve heat transfer area.
The foregoing description outlined rather broadly preferred and alternative feature of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should realise such equivalent conception do not depart from the spirit and scope of the invention in its broadest form.
The drawings are given by way of non-limitative example to explain the nature of the invention.
The accompanying drawings are intended to provide further understanding of invention and are incorporated in and constitute a part of invention. The drawings illustrate an embodiment of invention and together with the description illustrate principle of invention.
The drawings should not be taken as implying any necessary limitation on the essential scope of invention.
The various features of the novelty, which characterise the invention, are pointed out particularly in the claims annexed to and forming part of disclosure. For a better understanding of invention, its operating advantages, and specific objects obtained by its use, reference should be made to the drawings and descriptive matter in which there are illustrated and described preferred embodiments of invention.
A split valve plate configuration for an air cooled compressor in a motor vehicle braking system is characterised by incorporation of this special valve plate and cover configuration. The said valve plate and cover is fastened in between cylinder head and cylinder block of the air compressor and it comprises the inlet and delivery valves for allowing air into and out side of compressor cylinder bore. During operation of compressor the valve plate and valve plate cover combination reduces the heat transfer from valve plate to inlet air, reduces the heat transfer from hot delivery air to air in cylinder bore through valve plate and increases the heat dissipation through extended surface of valve plate cover beyond cylinder head contact area.
The described features make the valve plate more efficient in preventing heat flow and reducing the heating of air in cylinder bore. At the same time the extended surface area of valve plate cover make it more efficient in dissipating the heat to atmosphere and thereby improving the cooling efficiency of the cylinder head in the air compressor.
This invention will now be described with reference to the accompanying drawings, which illustrate by way of example, and not by way of limitation, one of several possible embodiments of the baffle proposed herein. In the drawings,
Figure 1 - illustrates the sectional view of the cylinder head of the air compressor with conventional valve plate.
Figure 2 - illustrates the sectional view of the cylinder head of the air compressor with split valve plate.
Figure 3 - illustrates the exploded view of the valve plate according to invention
The configuration of a conventional cylinder head assembly is illustrated in figure 1.
The cylinder head assembly consists of a cylinder head (1), valve plate (2), Inlet valve (3) and Delivery valve (4). The entire cylinder head assembly is mounted on the cylinder block (5). The delivery cavity of the cylinder head (1) consists of plurality of pin (6) like projections so as to increase the surface area of cooling. The valve plate (2) has two delivery passages (7) to allow the passage of compressed air from cylinder bore to delivery cavity. Further there is provided delivery valve (4) over the delivery passage (7). A governor plate (8) is placed over the delivery valve (4) so as to control the lift of the delivery valve (4).
The valve plate separating cylinder bore and cylinder head is a solid metal plate, which allows heat flow across its boundary. The heat generated during the compression process increase the temperature of valve plate and thus during the suction process of the compressor it heats up the incoming air in the inlet cavity of the cylinder head. During suction there will be heat flow from high temperature air at delivery cavity of the cylinder head to the air in cylinder bore.
The very objective of the Invention is to over come the problem associated with the prior art. The problem of direct heat transfer from valve plate surface to incoming inlet air and hot air in delivery cavity to air in cylinder bore and heat is addressed by incorporation of split valve plate with air gap in between them. The configuration of the split valve plate is explained in detail in figure 3 of the drawings.
This figure illustrates the split valve plate configuration in the conr»pressor assembly. The cylinder bore and cylinder head is separated by valve plate (1) and valve plate cover (2) with air gap in between them. Because of the split configuration, the heat generated during previous compression process will not heat up the surface of the valve plate exposed to inlet cavity and thus it reduces the heating of inlet air during suction. At the same time delivery cavity (3) is filled with high temperature air, which was delivered during earlier cycle. The heat from this delivery cavity will not be transferred to air in cylinder bore (4) directly and thus it reduces the heating of air inside cylinder bore. Since the temperature of the air inside the cylinder bore is less than that of the air normally that it would have been, the heat generated during compression would also be less. The extended surface in the valve plate cover (2) dissipates the heat of the air in the delivery cavity and thus it reduces the temperature of the air in the delivery cavity.
Figure 3 is the exploded view of the split valve plate illustrating the valve plate (1) and valve plate cover (2) with extended surface. As explained in the description, enhancement of the cooling efficiency is obtained by reducing the heat conductivity of valve plate across top and bottom surfaces and maximising the heat flow towards sides.
It is understood that the invention has been explained in relation to specific embodiment. It is inferred that the foregoing description is only illustrative of the present invention and it is not intended that illustrative of the present invention and it is not intended that the invention be limited or restrictive thereto. Many other specific embodiments of the present invention will be apparent to one skilled in the art from
the foregoing disclosure. All substitution, alterations and modification of the present invention, which come within the scope of the following claims, are to which the preset invention is readily susceptible without departing from the spirit of the invention.
The scope of the invention should therefore be determined not with reference to the above description but should be determined not with reference to the above description but should be determined with reference to appended claims along with full scope of equivalent to which such claims area entitled.
A split valve plate configuration for an air cooled air compressor in a motor vehicle braking system which contains atmospheric air in between valve plate and valve plate cover, acts as insulator and reduces heat flow from high temperature top surface of valve plate to bottom surface of valve plate which is exposed to cylinder bore and thereby heating of air in cylinder bore is reduced.
A split valve plate configuration for an air cooled air compressor in a motor vehicle braking system as claimed in claim 1, the air between valve plate and valve plate cover acts as insulator and reduces heat flow from bottom surface of valve plate which is exposed to cylinder bore to inlet cavity of cylinder head and there by heating of inlet air before the air enters into the cylinder bore is reduced.
A split valve plate configuration for an air cooled air compressor in a motor vehicle braking system as claimed in claim 1, the projection of valve plate cover beyond the valve plate surface acts as a fin for dissipating the heat.
|Indian Patent Application Number||86/CHE/2004|
|PG Journal Number||08/2007|
|Date of Filing||06-Feb-2004|
|Name of Patentee||M/S. SUNDARAM CLAYTON LIMITED|
|Applicant Address||JAYALAKSHMI ESTATES, NO.8 HADDOWS ROAD, CHENNAI 600 006|
|PCT International Classification Number||F 04 B 39/10|
|PCT International Application Number||N/A|
|PCT International Filing date|