Vacuum pump with ventilating means

Abstract

A vacuum pump for supplying a machine assembly with a negative pressure includes a housing and a housing cover surrounding a delivery chamber. The delivery chamber includes a low-pressure region having a working inlet connected to the assembly, and a high-pressure region having a working outlet. A delivery member moveable within the delivery chamber, which, when moved, suctions air into the delivery chamber through the working inlet and expel it at an increased pressure through the working outlet. An outlet valve is arranged at or downstream or the working outlet and at least makes it difficult for air to flow back into the delivery chamber. The delivery chamber is connected to the external environment of the vacuum pump via a ventilating connection in order to establish at least partial pressure equalization with the external environment when the delivery member is stopped and a negative pressure prevails in the delivery chamber.

Description

RELATED APPLICATION DATA[0001]This application claims the priority of German patent application No. 10 2010 044 898.2-15, filed on Sep. 9, 2010, which is hereby incorporated in its entirety by reference.FIELD OF THE INVENTION[0002]The invention relates to a vacuum pump for supplying a machine assembly with a negative pressure. The assembly is assigned to a machine, preferably an engine and particularly preferably an internal combustion engine. It can be arranged directly on the machine or even within the machine or also retracted from it and can be operated together with the machine, preferably in accordance with the machine. The vacuum pump, when installed, is preferably driven by the machine, for example by a crankshaft or valve control shaft of an internal combustion engine. The invention relates in particular to a vacuum pump which is installed in a motor vehicle or is designed to be installed in a motor vehicle.BACKGROUND OF THE INVENTION[0003]Vacuum pumps in motor vehicles, fo...

AI Technical Summary

Benefits of technology

[0007]The ventilating connection is advantageously configured such that as a whole, over its entire flow path between the delivery chamber and the free environment, it counteracts the air flowing through it into the delivery chamber with a flow resistance which on the one hand enables pressure equalization at least substantially within a short enough time to prevent fluid from being suctioned to any appreciable extent, but which on the other hand is still of a magnitude such that it does not impair the effectiveness of the vacuum pump during operation to any practically relevant extent. The function of the outlet valve, namely that of closing the working outlet until a particular minimum positive pressure is reached and opening the working outlet when the minimum positive pressure is reached, is preserved. The ventilating connection is designed such that the minimum positive pressure is still reached in a lower range of the delivery rate of the pump. As mentioned, the ventilating connection is on the other hand designed to equalize the negative pressure which arises in the delivery chamber when the vacuum pump is in operation within a short time, when the delivery member is stopped, using air which flows in from the environment, such that fluid is not suctioned in any significant amount.

[0009]The ventilating connection can comprise a passage which leads into the delivery chamber and exhibits a small flow cross-section as compared to the working inlet or in particular the working outlet. The passage can in particular be straight, for example a simple transit bore. A straight passage can already form the ventilating connection as a whole. A straight passage is simple and can be calculated and manufactured exactly in relation to the speed of the desired pressure equalization. A straight passage, in particular in the manner of a calibrated bore, can however also be only part of the ventilating connection. The ventilating connection can for example also be groove-shaped or comprise a groove-shaped portion.

[0013]The outlet valve can for example be a leaf spring valve comprising a leaf spring which forms the valve body, is spring-elastically tensed against the valve seating and can for example be a simple single-layer plate spring. The ventilating connection can in particular lead through the leaf spring. It can be formed in the leaf spring as a straight passage. A passage can in particular be punched in such a leaf spring cost-effectively. The passage extends in the thickness direction of the leaf spring. Alternatively or additionally, the ventilating connection can lead through the valve seating, for example in the form of one or more local recesses which are open facing the valve body and through which air can flow past the valve body into the delivery chamber for the purpose of pressure equalization in accordance with the invention.

Problems solved by technology

This counteracts the suctioning of fluid and thus filling of the delivery chamber with fluid and the associated negative consequences when the vacuum pump is started up again.

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