Patent Application
20050276702
The present invention relates to a compressor. It finds particular application in conjunction with a compressor inlet control device which regulates the inlet pressure to an automotive air compressor and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Diesel engines of the type used in heavy vehicles (e.g., trucks) are commonly equipped with turbochargers, which use the exhaust gasses of the engine in order to compress atmospheric air to charge the intake manifold of the engine with air above atmospheric pressure. Use of turbochargers increases the efficiency of the engine substantially. Although turbochargers are most commonly used with diesel engines used on heavy duty trucks, it is possible that other devices which mechanically increase the pressure level at the intake manifold of the engine, such as superchargers, may also be used. As used in this patent application, the term “turbocharger” should be construed to also mean supercharger and other devices for mechanically increasing the pressure level at the intake manifold of the engine.
Heavy vehicles of the type equipped with turbocharged diesel engines are also commonly provided with an engine-operated air compressor which compresses atmospheric air for use in, for example, the vehicle air brake system. Accordingly, the present invention pertains to a system including an air compressor powered by the vehicle engine having an intake manifold and a turbocharger to increase the pressure level in the intake manifold of the engine to pressure levels greater than atmospheric pressure. The turbocharger has an outlet communicated to the intake manifold. The air compressor has an inlet and an outlet. The air compressor inlet is communicated with the outlet of the turbocharger so that the air communicated into the inlet of the air compressor has been compressed by the turbocharger to a pressure level greater than atmospheric pressure and the air compressor raises the pressure level at the inlet of the air compressor to a still higher pressure level at the outlet thereof.
Using the output of the turbocharger as the inlet of the automotive air compressor has several advantages. Air compressors have a tendency to pass lubricating oil into the air being compressed. Using turbocharger air tends to reduce this passing of oil into the air being compressed. Furthermore, compressor inlet air must be filtered, and by communicating the air compressor with the air (which has already been filtered) at the output of the turbocharger eliminates a separate air filter which would otherwise be necessary. Furthermore, since the inlet air to the air compressor has already been compressed to a pressure level above atmosphere, the air delivery of the air compressor can be increased. However, use of the turbocharger air is beneficial only if the pressure level of the output of the turbocharger is below a certain pressure level.
In one embodiment, an inlet control device includes a status valve, positioned as a finction of a status of a state of a compressor, and a means for regulating a delivered pressure to a compressor inlet as a finction of an input pressure, the position of the valve, and a rotational speed of the compressor.
In another embodiment, an inlet control device includes a status valve and a reed valve. The status valve is positioned as a function of a status of a state of a compressor. Also, the reed valve delivers a reed output pressure to an inlet of the compressor as a function of 1) a reed input pressure on an input side of the reed valve, 2) the position of the status valve, and 3) a rotational speed of the compressor.
In the accompanying drawings which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the embodiments of this invention.
With reference to
The status valve 14 is set as a function of a status of a state of the compressor 12. In one embodiment, the status valve 14 is a piston controlled as a f unction of a status signal to the compressor 12. More specifically, when the compressor 12 is in the “charge” or “load” condition, a “load” status signal is transmitted to the status valve 14 for setting the status valve 14 to the raised position, as shown in
While in the raised position, the status valve 14 creates free (unrestricted) fluid communication between the output side 24 of the control valve 20 and the compressor inlet 28. Therefore, substantially all of the pressure delivered to the output side 24 of the control valve 20 is delivered to the compressor inlet 28. Furthermore, the status valve 14 substantially seals the exhaust port 32. Therefore, substantially none of the pressure delivered to the output side 24 of the control valve 20 passes to atmosphere via the exhaust port 32 while the status valve 14 is in the raised position.
While in the lowered position (see
As discussed above, a position of the status valve 14 controls fluid communication between the compressor inlet 28, the exhaust port 32, and the output side 24 of the control valve 20.
The control valve 20 reduces pressure at the output side 24 as compared to pressure on the input side 22. In one embodiment, the pressure reduction at the output side 24 is proportional to the net mass flow rate passing through the control valve 20. More specifically, the pressure on the output side 24 increases as the mass flow rate on the output side 24 increases. In other words, the pressure on the output side 24 decreases as a mass flow of the fluid pressure on the input side 22 increases. Since the mass flow rate is largely determined by the upstream pressure at 22 and the rotation speed of the compressor, the pressure reduction will be lowest at low upstream pressures and low rotational speeds and highest at high upstream pressures and high rotational speeds.
For the reasons discussed above, the control valve 20 acts as a means for regulating the pressure delivered to the compressor inlet 28 as a finction of an input pressure on the input side 22, the position of the status valve 14, and the mass flow rate. Furthermore, in one embodiment, the control valve 20 is a reed valve. However, other embodiments including other types of control valves are also contemplated. For example, it is also contemplated that the control valve 20 is a microprocessor controlled inlet-regulating valve. Alternatively, it is also contemplated that the control valve 20 is any type of pressure sensitive inlet regulating valve.
The control valve 20 controls the amount of the delivered pressure on the output side 24 as a finction of the pressure on the input side 22 and the compressor rotational speed. In one embodiment, the pressure on the input side 22 is proportional to an engine manifold pressure. The control valve 20 operates to control the amount of the engine manifold pressure on the input side 22 that is delivered to the output side 24. As discussed above, the delivered pressure on the output side 24 of the control valve 20 is inversely proportional to mass flow through the valve 20. Therefore, when the compressor 12 is operating in the “load” mode, the pressure on the input side 22 is increased by fluid being drawn into the compressor and, furthermore, the amount of the pressure delivered from the input side 22 to the output side 24 decreases.
For example, in the embodiment discussed above in which the control valve 20 is a reed valve, the control mechanism 26 of the reed valve moves closer to a valve plate 42 at the output side 24 as the mass flow rate increases. The same effect is achieved as fluid is being drawn into the compressor inlet 28.
It is to be understood that the mass flow at 22 and 24 must always be equal due to continuity of mass law. If the mass flow rate is zero (0), there is not any movement of the reed 26 toward the plate 42. Therefore, the reed closes off more and more as the mass flow rate increases.
As discussed above, the inlet control device 10 illustrated in
While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept.
