This application claims priority of Indian Application No. 2463/DEL/2004, filed Dec. 10, 2004.
The invention relates to condensers in an air-conditioning system and more particularly condensers for automobile air-conditioners.
At the outset, caulking as a process with reference to this invention refers to a joining process wherein two components are crimped, bent, or deformed at the joining juncture, without the use of any external filler material. Caulking is usually carried out prior to brazing in the brazing furnace to ensure that the components to be brazed are retained against each other.
An air-conditioning system typically consists of the following components: a compressor, condenser, expansion valve and evaporator. The condenser receives high pressure, high temperature gaseous refrigerant from the compressor. The condenser is functional in condensing the refrigerant vapors to the liquid phase. The high-pressure condensed liquid refrigerant is converted to low-pressure liquid/vapor refrigerant in the expansion device and is finally sent to the evaporator where the refrigerant evaporates. The vaporized refrigerant is then sent to the compressor to be recycled through the system.
However, a common drawback with the typical air-conditioning system is that the refrigerant leaving the condenser is not always in the completely liquid phase. To remedy this situation, the air-conditioning system is provided with a receiver-tank that receives the refrigerant from the condenser before passing it to the expansion device. The primary purpose of the receiver-tank is to ensure that all refrigerant passed to the expansion device is in the liquid phase. This in turn ensures that the refrigerant entering the evaporator is of low quality and low enthalpy, so as to increase the evaporator's ability to absorb heat from the ambient surroundings. The receiver tank acts as a reservoir for excess liquid refrigerant to assure that only liquid is fed to the expansion device in spite of system changes typically caused by the operation of the compressor. For example, in an automotive air-conditioning system, the compressor is frequently stopped and started.
Additionally, the receiver-tank is also provided with means for removing moisture from the refrigerant to assure its purity and possible internal corrosion of the evaporator.
Initially, the receiver-tank was formed as a unit separate from the condenser, placed downstream of the condenser and upstream of the expansion device and connected to these devices by appropriate piping. In such a situation, the packaging space is increased by an amount at least that of the receiver-tank. It is also necessary to secure the receiver-tank to the vehicle body in such a manner that it is sufficiently durable against vibration independent of the condenser. Furthermore, the manufacture, part control, and assembly work of the connecting means between the condenser and the receiver-tank is required, which eventually increases the cost of the vehicle air-conditioner.
Japanese patents 3-87572, 4-103973 and 4-131667 have attempted to remedy this situation by providing solutions such as directly brazing together of components. However, the solutions offered by these patents also have limitations. For example: In Japanese patent 4-103973 in assembling the receiver tank and the condenser, the first header pipe of the condenser is connected to the receiver tank by brazing. However, the brazing of those members, especially the receiver tank is difficult, because they are each in the form of a cylinder that is large in thermal capacity. That is, the header and the receiver tank are combined with other members forming the condenser and fixed with a jig and then the resultant assembly is set in a heating furnace. In the heating furnace, the assembly is heated at a temperature which is higher than the melting point of the brazing material applied to at least one of the two members (which are to be connected to each other) and is lower than the melting point of the base material. In those members, the brazing material on each member is melted so as to be connected to the mating member. In the above-described members the first header pipe and receiver tank are both large in thermal capacity, and therefore the brazing of those members is rather difficult. That is, the members are increased in temperature slowly when compared with the other members; i.e. the melting of the brazing material on at least one of the two members takes time so that the resultant brazing of the two members is liable to be unsatisfactory. In addition, the time required for those members to be connected to each other by brazing is unavoidably long; i.e. the assembling work of the receiver tank and the condenser is low in work efficiency. Since the header and the receiver tank are cylindrical, the contact surface of them is linear, so that the brazing area is small, and the coupling force is not great enough.
Japanese Patent Application No. 4-320771 discloses a technique of forming a flat portion on a side surface of the header of the condenser together with forming a flat portion also on the receiver tank and performing integral brazing with the two flat portions in an aligned state. The method allows for an increase in area of contact and therefore provides for a stronger braze. However, during brazing the header and the receiver tank are retained by jigs of wire, and the provisional retaining force declines in the furnace due to change in thickness of respective members due to melting of brazing material, change in hardness of respective members etc. Further, the joining surfaces of the header and receiver tank are susceptible to slippage and rate of joining defects due to slippage is high.
U.S. Pat. No. 6,052,899 overcomes some of the aforementioned difficulties by providing a coupling bracket or connector that is smaller in thermal capacity than the header of the condenser and the receiver tank. One end of the coupling bracket is secured to the outer cylindrical surface of the header and the other end is secured to the outer surface of the receiver tank by brazing. The provision of coupling brackets or connectors to join the header and the receiver tank allows for better brazing characteristics. Also as the area of the junction of the coupling bracket and the receiver tank and the header are large enough the coupling force of the two members is high.
Typically two connectors are used between the header and the receiver tank. The connectors are hollow in that they have a path for the refrigerant to flow through them. Two holes, one inlet and one outlet are made on corresponding locations of the header and the receiver tank. Refrigerant on passing through the condenser core is outlet to the receiver tank where liquid refrigerant only is outlet to the sub cooling stage of the condenser.
However, the use of connectors or coupling brackets suffers from manufacturing drawbacks specifically in the joining of the connector to the header and the receiver tank. The connecting members are first caulked and then brazed to both the header and the receiver tank. One end of the connector is inserted into a hole in the condenser header and the other end of the connector is inserted into a corresponding hole of the receiver tank. The ends that are inserted into the header and receiver tank respectively are then caulked with the help of special and expensive tooling. (figure here showing header and receiver in dotted lines, connector ends before and after caulking). However, as the receiver tank is an extruded component and has a closed body, the caulking of the connectors with the receiver is a difficult and complicated process. Long tools are inserted into the receiver body to flare the connector end. This process sometimes also results in the tool damaging the threaded portion of the receiver that receives the cap filter sub-assembly. This results in the entire receiver tank being rejected. Poor caulking can lead to degraded brazing performance at the joining surfaces that in turn may result in refrigerant leakage. The complicated caulking process also requires expensive tooling and often results in higher rejections. Furthermore, the internal threads also tend to get damaged as some filler material of the brazing operation may flow into the threads and render them ineffective. In this case, the entire condenser along with the receiver tank has to be rejected as scrap as they have been brazed. This proves to be a strong economic deterrent of the existing receiver tanks.
The invention provides for an improved receiver tank for a condenser that allows for ease in manufacturing.
The invention provides for an improved receiver tank for a condenser that does not require expensive and complicated tooling.
The invention provides for an improved receiver tank for a condenser that provides for savings in cost and reduction in manufacturing waste.
The invention provides for an improved method of manufacturing a receiver tank for a condenser that does not require expensive and complicated tooling.
The invention provides for an improved method of manufacturing a receiver tank for a condenser that provides for savings in cost and reduction in manufacturing waste.
To meet the aforementioned objectives the invention provides for a receiver tank for an automobile air conditioner condenser comprising:
The invention also provides for a method of manufacturing an integrated receiver condenser wherein a first half and a second half of a receiver are joined together to form the receiver.
The accompanying drawings illustrate the preferred embodiments of the invention and together with the following detailed description serve to explain the principles of the invention.
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
Through out the patent specification, a convention employed is that in the appended drawings, like numerals denote like components.
With reference now to
Side plates (11,12) are joined to the first and second header (3,4) at both ends maintaining the strength of the refrigerant condenser (1).
High pressure, high temperature gaseous refrigerant from the compressor enters the condenser through inlet (5) in the second header (4). The refrigerant then flows though a series of passes between the first header (3) and second header (4), before finally exiting the condenser tubes (7) at receiver inlet (9).
The receiver has a vapor-liquid separation chamber for separating vapor-liquid of refrigerant. The receiver may be provided with means for filtering the refrigerant as well as for removing moisture from the refrigerant to assure its purity, thereby avoiding inefficient operation. Liquid refrigerant from the receiver tank leaves the receiver tank from the receiver outlet (10). This liquid refrigerant is then sub-cooled in the sub-cooler (8) and finally leaves the sub-cooler at outlet (6).
As can be seen from the figure, the receiver tank (2) and the first header (3) are cylindrical with connectors between them. Optionally, the receiver tank and the header may be of an elliptical, rectangular or other geometrical profile. The first header (3) consists of two halves, a plate header (31) and a tank header (27) as shown in Figure (10). It is the tank header to which the receiver is connected. Caulking a connector to the tank header (27) is not difficult as the tank header has an open profile. However, caulking the connector to the receiver tank (2) requires inserting the connector into the hole made in the cylindrical receiver and caulking it at its inside edge, which is a complicated task.
The invention therefore resides in splitting the receiver tank in two halves and a method of manufacturing an integrated condenser receiver using the split receiver tank. At least one of the two halves are provided with means to join with the other half. These means may be ribs for caulking or slots for a sliding connection.
The novel receiver tank in accordance with the invention may be better visualized with reference to
With reference now to
The connectors in accordance with an embodiment of the invention may be better understood with reference to
A cap support (26) in accordance with this embodiment of the invention is then attached to the lower end of the left half as shown in
With reference now to
The tank header also has ribs (30) on its edges that are used to caulk the tank header to the plate header.
The tank header (27) is now connected to the plate header (31) of the first header (3) to complete the condenser assembly, as shown in figure (10). The tank header is caulked to the plate header by the tank header ribs (30), as may be seen in
The other or right half (33) of the receiver tank (2) is attached to a separator (34) that has rib (35), as shown in
The right half (33) of the receiver tank has ribs (37) at its edges. Referring now to
To complete the receiver tank, a receiver cap (40) with ribs (41) is caulked to the upper end of the receiver tank, and is depicted by
As mentioned earlier and as illustrated by
The invention thus also simplifies the manufacturing process by eliminating the internally threaded receiver tank with a cap support that has internal threads. Thus damage to the threads during the process of caulking is also avoided since cap support is added to the assembly after the caulking process.
In an alternate embodiment, another method of assembling the cap support to the two halves of the receiver is described. With reference now to
With reference now to
Another advantage provided by this particular embodiment is that the entire assembly takes up lesser space in the engine cabin area since the receiver is moved closer to the condenser.
It will readily be appreciated by those skilled in the art that the present invention is not limited to the specific embodiments herein shown. Thus variations may be made within the scope and spirit of the accompanying claims without sacrificing the principal advantages of the invention.
Number | Date | Country | Kind |
---|---|---|---|
2463/DEL/2004 | Dec 2004 | IN | national |