Claims:I claim:

1. An air charging device (100) for an engine, comprising at least:

a housing (102) with an inlet (104) and an outlet (106);

at least a part of a drive shaft (108) located within said housing (102);

a first ring member (110) mounted on said drive shaft (108);

a second ring member (112) mounted on said first ring member(110); and

a spring loaded piston (114) located with respect to a second ring member (112) in a way such that movement of said spring loaded piston (114) within said housing (102) creates an area for suction and compression of air within said housing (102); characterized in that

said second ring member (112) provided with a groove; and

a roller element (116) mounted on one end of said spring loaded piston (114), said roller element in engagement with said second ring member (112).

2. The air charging device (100) of claim 1, said roller element (116) is mounted on one end of said spring loaded piston 114 in a manner such that said roller element (116) is in engagement with said second ring member (112).

3. The air charging device (100) of claim 1 and 2, wherein said roller element (116) is in engagement with said groove on said second ring member (112).

4. The air charging device (100) of claim 1, wherein said second ring member is circumferentially mounted on said first ring member (110).

5. The air charging device (100) of claim 1, wherein said drive shaft (108) is located eccentrically with respect to said first ring member (110).

6. The air charging device 100 of claim 1, wherein said air charging device (100) is a supercharger.
, Description:Field of the invention
[0001] This invention relates to the field of air charging device for engines.

Background of the invention
[0002] The use of rotary piston compressors in superchargers is well known in the art. These compressors make use of a reciprocating action of the piston to drive a ring member within the housing of the compressor. The movement of the ring member within the housing with respect to the piston, creates an area within the housing for sucking and compressing the air. At higher speeds of movement of the ring member, the contact between the ring member and the piston will be critical. The contact may require lubrication. If a lubricant like oil is used, then there is a possibility of oil mixing with the air that is getting charged. Hence, there is a need for better sealing arrangement in a supercharger.

[0003] Prior art patent application EP775812 discloses a seal arrangement for an engine-driven supercharger comprising a housing (1) containing a rotor chamber (2) in which rotors (4, 5) are rotatably mounted on shafts (6a, 6b) extending into a shaft chamber (33a, 33b), and supported on bearings (7a, 7b) fed by lubricating oil. External air is sucked into the rotor chamber (2) by negative pressure, and compressed, and an oil seal (12) is fitted to the rotor shafts (6a, 6b) between the bearing (7a, 7b) and the rotor chamber (33a, 33b), defining an oil chamber (11). An air chamber (16a, 16b) is defined between the oil seal and the rotor chamber, and communicates with the outside via an air passage (17a). The oil seal (12) is made from rubber sheet material, and air seal (20) and labyrinth seals (24a, 24b) are made from "Teflon" (RTM) sheet material.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] FIG. 1 illustrates an air charging device.
Detailed description of the embodiments
[0006] FIG. 1 illustrates an air charging device. The air charging device 100 comprises at least a housing 102 with an inlet 104 and an outlet 106. At least a part of the drive shaft 108 is located within the housing 102. A first ring member 110 is mounted on the drive shaft 108. The drive shaft 108 is located eccentrically with respect to the first ring member 110. A second ring member 112 is mounted on the first ring member 110 and is provided with a groove. The second ring member may be circumferentially mounted on said first ring member 110. A spring loaded piston 114 is located with respect to the second ring member 112 in a way such that movement of the spring loaded piston 114 within the housing 102 creates an area for suction and compression of air within the housing 102. A roller element 116 is mounted on one end of the spring loaded piston 114 and is in engagement with the second ring member 112. The roller element 116 comprises a roller support 115 and a roller 113. The roller element 116 may be mounted on one end of the spring loaded piston 114 in a manner such that the roller element 116 is in engagement with the second ring member 112. The roller 113 is in engagement with the groove on the second ring member 112.

[0007] The working of the air charging device 100 will be explained herewith in further detail. The air to be compressed is received through the inlet 104 of the air charging device 100. The rotation of the drive shaft 108 causes the first ring member 110 to rotate. A 360 degree rotation of the ring member 110 within the housing 102 defines one single cycle of receiving, compressing and delivering air out of the housing 102 of the air charging device 100 and into the inlet of the engine. The second ring member 112 that is mounted on the first ring member 110 follows the path of the first ring member 110 within the housing 102. The combined movement that is rotation of the first ring member 110 and movement of the second ring member 112 creates a volume or space within the housing 102 for air to enter through the inlet 104. The movement of the spring loaded piston 114 separates and seals the inlet 104 and outlet 108 chamber of the air charging device 100. In other words the air that is entering the housing 102 through the inlet 104 will not get mixed with the air that is already compressed within the housing 102 Since the roller element 116 is in engagement with the second ring member 112 the roller 113 present in the roller element 116 transmits the motion of the second ring member 112 to the spring loaded piston 114. The purpose of roller element 116 is to avoid sliding contact between spring loaded piston and second ring 112. The roller 113 makes rotation only based on the movement of the second ring member 112. Advantage of this contact is to have lesser wear and with suitable material selection, and avoid the need for lubrication and/ or the oil chamber.

[0008] The movement of the spring loaded piston 114 and the rotation of second ring member 112 results in air to be sucked into the housing 102, compressed and then delivered to the intake manifold of the engine through the outlet 106. The spring loaded piston 114 along with the second ring member ensures that there is no mixing of air that is entering the housing 102 and the compressed air that is being sent out of the housing 102 through the outlet 106. With the proposed air charging device 100, mixing of oil with air is avoided. The air charging device 100 may be used for single cylinder engines and the like. The air charging device 100 may also be used on any type of engines where the requirement of pulsating charge is necessary. Moreover, the movement first ring member 110, the second ring member 112, can be timed suitably so as to make it synchronous with intake stroke of the engine.

[0009] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of the type of air charging device, type of bearing used for the roller element. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.