Patent Application
20130133768
This application claims the benefit of DE 10 2011 119 649.1 filed on Nov. 29, 2011, the disclosure of which is hereby incorporated herein by reference in its entirety.
The present invention generally relates to a compressor system for a compressed-air supply arrangement that includes an adjustable throttle device arranged in the suction line of the compressor.
Compressor systems of the general type under consideration are used in utility vehicles that have subsystems operated by compressed air, such as for example brakes, air suspension systems, etc. Here, use is made of two compressors, which are charged by means of a turbocharger for the drive engine of the utility vehicle, and also naturally aspirating compressors. These fill a compressed-air tank with compressed air, from which the subsystems operated by compressed air are supplied with compressed air according to demand.
In order to reduce manufacturing costs, the compressors are conventionally permanently coupled in terms of drive to the associated drive engine, as a result of which the compressor is permanently driven while the drive engine is running. If, during ongoing operation, the fill pressure in the compressed-air tank reaches a fixed upper value, the compressor system is switched into an idle operating mode in order to reduce the power consumption thereof. If, owing to a demand for compressed air by a compressed-air consumer, the fill pressure in the compressed-air tank decreases and reaches a set lower value, the compressor system is switched into a load operating mode again, and the compressor refills the compressed-air tank.
For the idle operating mode of the compressor system, use is preferably made of a circulation circuit or a return flow circuit. In the case of the circulation circuit, the pressure line of the compressor is connected directly to the suction line thereof by means of a switching valve. Here, however, high pressure losses arise, and the installation of a check valve is necessary. In the case of the return flow circuit known for example from DE 39 09 531 A1, the suction valves of the compressor are not closed during the compression process. The air is therefore not compressed but rather flows back to the suction side. This however requires corresponding design and structural modification of the compressor for this specific mode of operation.
DE 10 2008 026 028 A1 describes a compressor system in which a piston compressor designed for natural aspiration can be supercharged if the suction air quantity falls below a predefined value. To set the compressor system into an energy-saving operating state, the air supply from a charge-air valve device and the air supply from an ambient-air valve device are completely shut off, and special measures are implemented in order to restrict the suction vacuum generated by the compressor, and thus an intake of oil. This known compressor system is also relatively cumbersome in terms of design and construction and is thus expensive to manufacture.
Against the foregoing background, it is, generally speaking, an object of the present invention to provide a compressor system for a compressed-air supply arrangement of efficient construction that minimizes compressor power consumption in the idle operating mode.
The invention is based on the realization that a large portion of the attainable minimization of power consumption is already attained even with a remaining residual throughput through the throttle device, wherein, in addition, in particular in the case of piston compressors, oil is prevented from passing out of the crankcase into the compression chamber.
In accordance with embodiments of the present invention, a compressor system for a compressed-air supply arrangement is provided that includes an adjustable throttle device arranged in the suction line of the compressor. The throttle device is adjustable between a fully open load position and an idle position with a predefined narrowed throttle cross section. The throttle device accordingly operates with two operating positions that are simple to implement in terms of control, specifically fully open and open with a predetermined small air throughput capacity. The throttle device may basically be used on its own or also in conjunction with a conventional idle system, wherein in the latter case, the effects of both measures are added together.
From a design aspect, the throttle device according to embodiments of the invention can be of simple configuration because it is easily insertable into the suction line or the suction path of the compressor, and therefore no additional lines and filters are required.
In one embodiment of the invention, the throttle device has a throttle element that is adjustable between a load position in which the suction cross section is fully opened up, and an idle position in which the predefined throttle cross section is left free. Accordingly, the idle position is defined by the latter of the two end positions of the throttle element, in which a certain small throttle cross section, which permits a small air throughput, remains free.
In another embodiment of the invention, the throttle device has a throttle element that is adjustable between a load position in which the suction cross section of the suction line is fully opened up, and an idle position in which the suction line is fully closed, wherein a fixed throttle with a predefined throttle cross section is however then provided substantially parallel to the suction cross section. The predefined throttle cross section is accordingly determined not by one of the two end positions of the throttle element, which in this case fully closes off the suction cross section, but rather by a fixed throttle with a defined throttle orifice.
The throttle element can, for example, be in the form of a throttle flap arranged pivotably in the suction line, or in the form of a slide piston that is displaceable, transversely with respect to the flow direction, in the suction line, or in the form of an adjustable iris aperture arranged in the suction line, which, in the idle position thereof, either leave a predefined throttle cross section free, or completely close off the suction cross section if a fixed throttle is provided parallel to the suction cross section.
In a further exemplary embodiment of the invention, the throttle element is in the form of a throttle flap arranged pivotably in the suction line, and the fixed throttle is in the form of a throttle aperture formed in the throttle flap itself, as will be discussed in greater detail hereinafter.
The throttle device can basically be arranged at any desired location in the suction path of the compressor, that is, outside the latter. In one embodiment of the invention, the throttle device is however integrated into the cylinder head of a piston compressor.
As already noted above, in an embodiment of the invention, the throttle device can be provided in addition to a conventional idle system, such as for example a circulation circuit, a return flow circuit or the like, wherein the throttle device further intensifies the idle effect imparted thereby.
In a further embodiment of the invention, the throttle device can be actuated by an actuator that can be activated by a control device as a function of predefined operating conditions. For this purpose, the control device is connected to a pressure sensor that preferably measures the pressure in a compressed-air tank. In this way, the compressor system can be operated automatically.
Lastly, the throttle device is preferably connected to an inlet line through which air pre-compressed by a supercharger (turbocharger or mechanically driven supercharger) can be supplied.
Still other objects and advantages of the present invention will in part be obvious and will in part be apparent from the specification.
The present invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts all as exemplified in the constructions herein set forth, and the scope of the invention will be indicated in the claims.
For a fuller understanding of the exemplary embodiments of the present invention, reference is had to the following description taken in connection with the accompanying drawings in which:
Referring now to the drawing figures,
The throttle device 8, which is arranged in the suction line 4, is adjustable between a fully open load position and an idle position with a predefined narrowed throttle cross section. The adjustment of the throttle device 8 is effected by means of an electric, hydraulic or pneumatic actuator 50, which is connected via a control line, indicated by a dotted line, to a control unit 14. The control unit 14 is furthermore connected via a sensor line, indicated by a dashed line, to a pressure sensor 52, which measures the air pressure in the compressed-air tank 54. With the knowledge of the air pressure in the compressed-air tank 54, the throttle device 8 is adjustable into the respectively desired operating position.
Between the compressor 2 and the throttle device 8, the suction line 4 has a volume that duly exceeds a minimum size, but which is not limited in terms of its maximum size.
It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained, and since certain changes may be made in the above constructions without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102011119649.1 | Nov 2011 | DE | national |
