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.

What is claimed is: 
     
         1 . A vacuum pump for supplying a machine assembly with a negative pressure, said vacuum pump comprising:
 a) a housing and a housing cover which surround a delivery chamber,   b) wherein the delivery chamber comprises a low-pressure region comprising a working inlet which can be connected to the assembly, and a high-pressure region comprising a working outlet for air;   c) a delivery member which can be moved within the delivery chamber and which, when moved, can suction air into the delivery chamber through the working inlet and expel it at an increased pressure through the working outlet;   d) an outlet valve which is arranged at the working outlet or downstream of the working outlet and at least makes it difficult for air to flow back into the delivery chamber;   e) and a fluid feed through which lubricating or sealing fluid can be fed to the delivery chamber,   wherein   f) the delivery chamber is connected to the external environment of the vacuum pump via a ventilating connection in order to establish an at least partial pressure equalization with the external environment when the delivery member is stopped and a negative pressure prevails in the delivery chamber.   
     
     
         2 . The vacuum pump according to  claim 1 , wherein if the assembly is connected to the vacuum pump, an air feed which connects the assembly to the delivery chamber via the working inlet exhibits, as a whole, a lower flow resistance than the ventilating connection. 
     
     
         3 . The vacuum pump according to  claim 1 , wherein a flow cross-section of the working outlet is at least ten times as large as a flow cross-section of the ventilating connection. 
     
     
         4 . The vacuum pump according to  claim 1 , wherein the ventilating connection is dimensioned such that when the delivery member is stopped, pressure equalization is at least substantially complete within a few seconds. 
     
     
         5 . The vacuum pump according to  claim 4 , wherein pressure equalization is at least substantially complete in at most one second. 
     
     
         6 . The vacuum pump according to  claim 1 , wherein the ventilating connection comprises a passage which leads into the delivery chamber, for example a transit bore which ports into the delivery chamber, and exhibits a small flow cross-section as compared to the working inlet and also as compared to the working outlet. 
     
     
         7 . The vacuum pump according to  claim 6 , wherein the passage is a straight passage. 
     
     
         8 . The vacuum pump according to  claim 1 , wherein the ventilating connection comprises an inlet for ambient air in the high-pressure region of the delivery chamber. 
     
     
         9 . The vacuum pump according to  claim 1 , wherein the inlet for the ambient air is near to the working outlet. 
     
     
         10 . The vacuum pump according to  claim 1 , wherein the ventilating connection connects the delivery chamber to the environment through the working outlet. 
     
     
         11 . The vacuum pump according to  claim 10 , wherein the ventilating connection ports into the working outlet as viewed from the environment. 
     
     
         12 . The vacuum pump according to  claim 1 , wherein the ventilating connection leads through the outlet valve. 
     
     
         13 . The vacuum pump according to  claim 1 , wherein the outlet valve comprises a valve seating and a valve body which is elastically tensed against the valve seating and can be raised off of the valve seating against an elastic restoring force, and wherein the ventilating connection leads through the valve body or the valve seating. 
     
     
         14 . The vacuum pump according to  claim 13 , wherein the outlet valve is a leaf spring valve and the valve body is a leaf spring which is spring-elastically tensed against the valve seating, and wherein the ventilating connection leads through the valve body or the valve seating. 
     
     
         15 . The vacuum pump according to  claim 14 , wherein the ventilating connection comprises a passage extending through the leaf spring in a thickness direction of the leaf spring. 
     
     
         16 . The vacuum pump according to  claim 13 , wherein the ventilating connection comprises a recess in the valve seating, through which air can flow from the external environment past the valve body into the delivery chamber, the recess facing the valve body. 
     
     
         17 . The vacuum pump according to  claim 1 , wherein the ventilating connection leads through the housing or the housing cover or a joining region between the housing and the housing cover. 
     
     
         18 . The vacuum pump according to  claim 1 , wherein the vacuum pump is arranged in or on a vehicle which is driven by an engine and wherein the assembly is connected at the working inlet or the vacuum pump is designed to be installed in this way. 
     
     
         19 . The vacuum pump according to  claim 18 , wherein the assembly is a brake booster. 
     
     
         20 . The vacuum pump according to  claim 1 , wherein the vacuum pump is a rotary pump, and the delivery member is a feed wheel which can be rotated in the delivery chamber. 
     
     
         21 . The vacuum pump according to  claim 20 , wherein the vacuum pump is a vane cell pump. 
     
     
         22 . The vacuum pump according to  claim 20 , wherein the delivery member is a vane wheel comprising a rotor and at least one vane which can be moved relative to the rotor. 
     
     
         23 . The vacuum pump according to  claim 1 , wherein the vacuum pump is at least partially arranged in a reservoir of the lubricating or sealing fluid which serves to lubricate or seal, and wherein at least a lower region of the pump is immersed in the fluid, and wherein the ventilating connection leads into the delivery chamber above an upper level of the fluid or is extended beyond the upper level.