AIR INLET ARRANGEMENT FOR AN AIR COMPRESSOR
An air inlet arrangement for an air compressor intended to be arranged on a vehicle includes an air inlet tube for providing air to an air compressor, and an air intake conduit for providing air to an internal combustion engine. The air inlet tube is provided with an end portion having an inlet opening and is mounted to the air intake conduit. The end portion is inserted in the air intake conduit in such a way that the inlet opening is arranged inside the air intake conduit, and the inlet opening is arranged to face towards the main direction of the intended air flow in the air intake conduit.
The present invention relates to an air inlet arrangement for an air compressor, and to an air compressor system.
In heavy vehicles, such as trucks and buses, there is a need for compressed air. The compressed air is provided to ensure the function of different pneumatic components and equipments of the vehicle. The air compressor is usually driven by a prime mover of the vehicle, such as an internal combustion engine which is primarily used for driving the vehicle. The compressed air may be delivered to a storage tank from which compressed air is supplied to the pneumatic components and equipments. Turbocharged engines are commonly employed as the prime mover in commercial vehicles and thus also to power the air compressor system. A turbocharger is driven by the exhaust gases of the engine for supplying pressurised air to the engine so as to increase the efficiency of the engine.
In the air compressor air is compressed in one or more compression cylinders by one or more reciprocating pistons. The compressed air is then stored in an air tank and used downstream for different pneumatic equipments, for example the brakes, the suspension system, a power-clutch, and/or other equipment. The compressor pistons have sealants that help to keep the compressed air on one side of the piston and to keep the lubricating oil on the opposite side of the piston, i.e. the sealants help to keep the oil away from the compressed air. However, such sealants are not completely effective which implies that some oil can enter the compressed air in aerosol form. The content of oil in the air due to such leakage is dependent on for example the temperature and the rotational speed of the compressor. The oil per se as well as other substances into which the oil can be been transformed, particularly at high temperatures, can be harmful to components in the pneumatic system, such as air dryer equipment, sealants, valves or sensors.
It is desirable to provide an air inlet arrangement for an air compressor of the kind referred to in the introduction, which inlet arrangement can reduce the leakage of oil into the compressed air.
By the provision of an air inlet arrangement where the end portion of the air inlet tube is inserted in an air intake conduit used for providing air to an internal combustion engine, in such a way that the inlet opening of the air inlet tube is arranged inside the air intake conduit, and the inlet opening is arranged to face towards the main direction of the intended air flow in the air intake conduit, the pressure of the air in the air inlet tube can be increased. This in turn will counteract oil leakage to the compressed air.
The invention is based on the insight that if the air flow to the compressor for some reason is restricted, the compressor has to work harder to be able to deliver the requisite compressed air to the vehicle. With such a restricted air flow, the oil leakage from the crankshaft side of the piston to the air side of the piston of the compressor may increase because air from the crankshaft side can more easily pass the sealants and reach the air side of the piston.
The main inventive concept is that the inlet opening of the air inlet tube is exposed to a direct air flow of the air in the air intake conduit. By the arrangement according to the invention the air inlet tube for providing air to the air compressor is “pre-loaded” by means of the flow in the air intake conduit. This in turn reduces the work that the air compressor has to do and the leakage of any oil/air-mixture from the crankshaft region to the cylinder space where air is compressed is counteracted.
The feature that “the inlet opening is arranged to face towards the main direction of the intended air flow in the air intake conduit” can be achieved in different ways. Basically two parameters are important to expose the inlet opening to the air flow inside the air intake conduit; the direction of the end portion of the inlet tube relative to the main air flow in the air intake conduit at the position where the inlet tube is mounted to the air intake conduit, and the shape of the end portion which is arranged inserted in the air intake conduit.
According to one embodiment of the invention the longitudinal extension of the end portion of the air inlet tube, in the direction away from the air intake conduit, has one extension component which is perpendicular to the main direction of the intended air flow in the air intake conduit and a second component which has the same direction as the main direction of the intended air flow in the air intake conduit. The end portion of the air inlet tube is preferably arranged at an angle α relative to the main direction of the intended air flow in the air intake conduit, where the air inlet tube angle α is in the interval 10°<α<80°. In many cases the angle α is suitably in the interval 20°<α<70°, and more preferably in the interval 30°<α<60°. Hereby the area of the inlet opening can be exposed to the air flow in the intake conduit.
According to a further embodiment of the invention the inlet tube is designed with a bevelled end portion which implies that the end surface of the inlet tube and the longitudinal centre line of the inlet tube form an angle β, where 0<β<90°. In many cases the end portion angle β is suitably in the interval 20°<β<70°, and preferably in the interval 30°<β<60°. Such a bevelled end portion can contribute to expose the inlet opening to the air flow in the air intake conduit.
By suitable selection of one or both above mentioned parameters, represented by α and β, the end portion of the air inlet tube can be arranged and/or designed in such a way that a geometrical plane defined by the inlet opening is arranged at an angle θ relative to the main direction of the intended air flow in the air intake conduit, wherein the inlet opening angle θ is in the interval 10°<θ<170°, and preferably in the interval 30°<θ<150°, and more preferably in the interval 45°<θ<135°. In some cases it is advantageous to use an inlet opening angle θ in the interval 60°<θ<120°, and preferably the inlet opening angle θ is substantially 90°. Hereby the flow of air in the air intake conduit can be effectively used for supplying air to the compressor via the air inlet tube.
According to a further embodiment of the invention, the point of the inlet opening of the air inlet tube which is situated closest to the inner surface of the wall of the air intake conduit, is situated at a distance B from the inner surface of the wall of the air intake conduit at the position where the air inlet tube is mounted to the air intake conduit. The distance B is preferably in the interval D/8<B<7D/8, and more preferably in the interval D/4<B<D/2. Hereby, disturbing phenomenon such as any turbulent flow along the inner wall of the air intake conduit can be avoided, and an appropriate positioning of the inlet opening of the air inlet tube in the air intake conduit can be achieved.
According to a further embodiment of the invention, the air inlet tube is mounted to a curved portion of the air intake conduit. In this way the design of the air intake conduit is used to place the air inlet tube appropriately in the air intake conduit so as to expose the inlet opening of the air inlet tube to the flow of air in the air intake conduit.
According to a further embodiment of the invention, the end portion of said air inlet tube is designed as a funnel. Hereby, the area of said inlet opening faced to the main direction of the intended air flow in the air intake conduit may be increased.
The invention also relates to a heavy vehicle comprising the air inlet arrangement according to the invention. Further advantages and advantageous features of the invention are disclosed in the following description.
With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.
In the drawings:
In
However, the force exerted by such branched off air flow is in many cases not sufficient to achieve an air flow into the inlet tube 10′. As it is indicated by an arrow F3′ pointing downwards in
An air intake conduit 20 is supplying an engine 130 with air for the combustion process. The air intake conduit 20 comprises a first part upstream of an air filter 140 and a second part downstream thereof. The air intake conduit 20 proceeds from the air filter 140 to a turbocharger 150 and into the engine 130. Since the air inlet tube 10 is mounted downstream the air filter 140, a separate air compressor filter is not always necessary, which in fact reduces maintenance costs considerably by eliminating the need for inspecting and/or changing a used or clogged separate air filter. Further, the risk of clogging the air filter of the air intake conduit is reduced, because the engine air filter is dimensioned for much greater air flows and will thus not clog as easy as a standard air compressor filter. An exhaust tube 160 leads from the engine 130 to the exterior. In the embodiment of the air inlet arrangement illustrated in
It has by the invention been realized, that the force of the existing air flow in said air intake conduit towards the engine for the combustion process therein can be utilized to reduce the amount of oil carryover in the air compressor by configuring the air inlet arrangement for the air compressor appropriately.
The force K with which an air flow is acting may be found by the following equation:
K=p·A·V2,
where p is the density of the air flow, A is the sectional area of the air inlet tube in question and V is the velocity of the air flow. Accordingly, K is a function of the sectional area of the air inlet tube 10 and of the air flow velocity squared at a given point in said tube. Further, these two factors are interrelated in that by increasing said sectional area the velocity is lowered.
Returning to
Although it is shown in
With reference to
As appears from
In
In other words, the end portion 40 can preferably be designed and/or arranged in such a way that a geometrical plane 27 defined by the inlet opening 11 is arranged at an angle θ relative to the main direction F2 of the intended air flow in the air intake conduit 20, wherein the inlet opening angle θ is in the interval 10°<θ<170°.
In
Although the sectional area of the air intake conduit 20 is the same before and after the position where the air inlet tube 10 is mounted as illustrated in for example
With reference to all embodiments of the invention described herein, depending on the material used for the air intake conduit 20 and the air inlet tube 10 to be connected to each other, e.g. metal, plastic, etc., the skilled person is aware of different techniques to join these components, such as e.g. welding, using an adhesive, or the like. It is to be noted, that despite the fact that the figures indicate that the air inlet tube 10 and the air intake conduit 20 have a circular cross section, any other suitable cross sectional shape of the current components can be utilized as an alternative. Preferably, the sectional shape of the end portion 40 of the air inlet tube 10 and the sectional shape of the air intake conduit 20 are selected to provide the inlet opening 11 with a suitable form for creating a first air flow of an increased magnitude, i.e. the inlet opening 11 is configured with a shape to enable and facilitate the branching off of air into the air inlet tube.
In
In
In
In
In
In
Further perceivable, but not shown alternatives could comprise fan-like guide blade structures, which guide blades extend in radial direction from e.g. a funnel shaped end portion to the inner surface of the air intake conduit. These guide blades could be into contact with and/or being attached to the inner surface of the air intake conduit. This in turn may increase the velocity of the first air flow into the inlet opening 11.
Other alternatives are perceivable, such as air inlet arrangements comprising air flow scooping devices, such as fans, bellows, flaps, skirts, filters and the like.
In the above, the invention is explained in relation to an internal combustion engine powered air compressor for a truck. However, it has by the invention been realized, that any air compressor, which is provided in combination with an air intake for a combustion process, may be utilized for enabling the arrangement according to the invention by selecting a suitable setup. Different types of suitable air compressors comprise positive displacement compressors, such as reciprocating or piston, rotary screw, or rotary sliding vane compressors, or dynamic compression compressors such as centrifugal compressors and other types of compressors. Different types of suitable prime drivers, which need air for the combustion, are e.g. gaseous fuel engines or turbines, diesel or petrol fuel engines or the like. The invention is suitable for diesel engines with or without a turbocharger.
It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.
Claims
1. An air inlet arrangement for an air compressor intended to be arranged on a vehicle, comprising an air inlet tube for providing air to an air compressor, and an air intake conduit for providing air to an internal combustion engine, the air inlet tube being provided with an end portion having an inlet opening and being mounted to the air intake conduit, wherein the end portion of the air inlet tube is inserted in the air intake conduit in such a way that the inlet opening is arranged inside the air intake conduit, and the inlet opening is arranged to face towards a main direction of an intended air flow in the air intake conduit.
2. An air inlet arrangement according to claim 1, wherein a longitudinal extension of the end portion of the air inlet tube, in a direction away from the air intake conduit, has one extension component which is perpendicular to the main direction of the intended air flow in the air intake conduit and a second component which has a same direction as the main direction of the intended air flow in the air intake conduit.
3. An air inlet arrangement according to claim 2, wherein the end portion of the air inlet tube is arranged at an angle α relative to the main direction of the intended air flow in the air intake conduit, the air inlet tube angle α being in the interval 10°<α<80°.
4. An air inlet arrangement according to claim 3, wherein the air inlet tube angle α is in the interval 20°<α<70°.
5. An air inlet arrangement according to claim 3, wherein the air inlet tube angle a is in the interval 30′<α<60°.
6. An air inlet arrangement according to claim 3, wherein the air inlet tube angle α is substantially 45°.
7. An air inlet arrangement according to claim 1, wherein the inlet tube is designed with a bevelled end portion in such a way that a main extension direction of the end surface of the inlet tube and a longitudinal center line of the inlet tube form an end portion angle β, where 0<β<90°.
8. An air inlet arrangement according to claim 7, wherein the end portion angle β is in the interval 20°<β<70°.
9. An air inlet arrangement according to claim 7, wherein the end portion angle β is in the interval 30°<β<60°.
10. An air inlet arrangement according to claim 7, wherein the end portion angle β is substantially 45°.
11. An air inlet arrangement according to claim 1, wherein the end portion is arranged in such a way that a geometrical plane defined by the inlet opening is arranged at an angle θ relative to the main direction of the intended air flow in the air intake conduit, the inlet opening angle θ being in the interval 10°<θ<170°.
12. An air inlet arrangement according to claim 11, wherein the inlet opening angle θ is in the interval 30°<θ<150°.
13. An air inlet arrangement according to claim 11, wherein the inlet opening angle θ is in the interval 45°<θ<135°.
14. An air inlet arrangement according to claim 11, wherein the inlet opening angle θ is in the interval 60°<θ<120°.
15. An air inlet arrangement according to claim 11, wherein the inlet opening angle θ is substantially 90°.
16. An air inlet arrangement according to claim 1, wherein a point of the inlet opening of the air inlet tube which is situated closest to a wall of the air intake conduit, is situated at a distance from an inner surface of the wall of the air intake conduit at a position where the air inlet tube is mounted to the air intake conduit.
17. An air inlet arrangement according to claim 16, wherein the distance between the point of the inlet opening and the intake conduit wall is in the interval D/8<B<7D/8, where D is a diameter or corresponding measure of the air intake conduit.
18. An air inlet arrangement according to claim 16, wherein the distance between the point of the inlet opening and the intake conduit wall is in the interval D/4<B<D/2, where D is a diameter or corresponding measure of the air intake conduit.
19. An air inlet arrangement according to claim 1, wherein the air inlet tube is mounted to a curved portion of the air intake conduit.
20. An air inlet arrangement according to claim 1, wherein the end portion of the air inlet tube is a funnel.
21. An air compressor system for a vehicle, comprising an engine and air compressor driven by the engine, and an air inlet tube for providing air to the air compressor, and an air intake conduit for providing air to the engine, the air inlet tube being provided with an end portion having an inlet opening and being mounted to the air intake conduit, wherein the end portion of the air inlet tube is inserted in the air intake conduit in such a way that the inlet opening is arranged inside the air intake conduit, and the inlet opening is arranged to face towards a main direction of an intended air flow in the air intake conduit.
22. A heavy vehicle comprising an air inlet arrangement according to claim 1.
23. An air inlet arrangement for an air compressor in a vehicle, the arrangement comprising an air inlet tube for the air compressor, and an air intake conduit for an internal combustion engine, wherein the air inlet tube is provided with an end portion having an inlet opening and is mounted to said the air intake conduit, wherein the inlet opening is configured in such a way as to provide a first air flow in the air inlet tube towards the air compressor, where this first air flow is created by a second air flow inside the air intake conduit towards the engine, and the air inlet tube is inserted in the air intake conduit in such a way that the inlet opening is positioned inside the air intake conduit.
Type: Application
Filed: Mar 29, 2007
Publication Date: Nov 18, 2010
Inventor: Pär Arvidsson (Dalsjofors)
Application Number: 12/293,426
International Classification: F04B 17/05 (20060101); F04B 39/04 (20060101);