Vane-cell pump

Details Vane-cell pump Vane-cell pump

1997-12-22

2001-06-12

Freay, Charles G. (Department: 3746)

Pumps

Diverse pumps

Moving partition or cylinder of rotary pump forms or...

C418S268000

Reexamination Certificate

active

06244830

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention pertains to vane-cell machines, and in particular, to vane-cell pumps.
2. Description of the Related Art
Conventional vane-cell machines are generally known, and comprise a rotor that rotates inside of a lifting ring that is arranged in a housing. The lifting ring has a contour that does not extend coaxially to the rotational axis of the rotor and forms at least one pump chamber. The rotor comprises radially extending slots, in which radially movable vanes are arranged. During the rotation of the rotor, the vanes are guided along the contour of the lifting ring, wherein respective chambers with changing volumes are formed between two adjacent vanes. In this case, a suction region and a pressure region are formed in accordance with the rotational movement of the rotor, wherein the suction region is arranged within the region of increasing volumes and the pressure region is arranged within the region of decreasing volumes. The suction region is connected to a suction connection of the vane-cell machine, and the pressure region is connected to a pressure connection of the vane-cell machine such that a fluid, e.g., oil, can be conveyed.
Machines known as lower vane pumps make up a lower vane pocket arranged within the suction region. The lower vane pocket is arranged in a lateral surface that limits the pump chamber. This lower vane pocket is connected to the pressure region of the vane-cell pump. The lower vane pocket is arranged in such a way that it is situated within the range of motion of lower vane chambers formed underneath the vanes in the slots in the rotor. In this case, the lower vane pocket extends over a certain rotational angle such that several lower vane chambers are simultaneously situated within the region of the lower vane pocket. Consequently, a fluid connection between the lower vane chambers and the lower vane pocket is attained, wherein the total surface of said fluid connection corresponds to the sum of the partial surfaces of the individual lower vane chambers that are currently in contact with the lower vane pocket.
The lower vane chambers change their cross-sectional surfaces in accordance with the rotational movement of the rotor and consequently change the radial position of the vanes, so the total surface also varies. The term “total surface” or “partial surface” of the fluid connection refers to the free cross-sectional surface of the fluid connection between the lower vane groove and the lower vane chambers situated within the region of a lower vane groove. The volume flow pulsation of the lower vane pump is superimposed on the volume flow pulsation of the upper vane pump and thus forms the total volume flow pulsation of the vane-cell pump.
In conventional vane-cell pumps, the lower vane pocket that is assigned to the suction region extends over a relatively large rotational angle of the rotor, i.e., the lower vane pressure pockets that are also situated within the range of motion of the lower vane chambers can only extend over a relatively small rotational angle. These lower vane pressure pockets are also connected to the lower vane pocket via the lower vane chambers and a circumferential groove in a second lateral surface, or four pockets are connected to one another via a fluid connection that is open toward the lower vane chambers.
SUMMARY OF THE INVENTION
Although a relatively good pulsation behavior is attained with the lower vane pocket that extends over a relatively large rotational angle, such a vane-cell pump has an inferior cold-starting behavior due, it is believed, to the fact that the lower vane pressure pocket extends over a relatively small rotational angle. The lower vane pressure pockets are subjected to a pressure build-up via the lower vane pocket, the lower vane chambers, and the revolving groove. The pressure build-up counteracts the inward motion of the vanes during their movement into the pressure region of the vane-cell pump and is intended to dampen this inward motion.
The present invention is based on the objective of developing a vane-cell machine, in particular, a vane-cell pump, of the initially mentioned type, which is characterized by a superior pulsation behavior of the lower vane pump as well as a superior cold-starting behavior.
According to one aspect of the invention, this objective is attained with a vane-cell pump, including:
a housing;
a lifting ring within the housing, that forms at least one suction region and one pressure region;
a rotor mounted for rotation within the lifting ring, the rotor having a circumferential surface and radial slots that are arranged on the circumferential surface of the rotor;
a plurality of radially spaced apart vanes having lateral edges and arranged in said slots in a radially movable manner so as to cooperate with said lifting ring to form lower vane chambers between adjacent vanes;
first and second stationary, lateral surfaces carried on at least one of said housing and said lifting ring, said lateral surfaces adjoining the rotor and the lateral edges of the vanes in a sealing manner;
said first lateral surface comprising a groove that extends within the range of motion of the lower vane chambers and is open toward these lower vane chambers;
said second lateral surface defining a lower vane pocket which is coupled to the pressure region, extending a predetermined angular amount over an angular range of travel of said rotor, being located in the suction region and also within the range of motion of the lower vane chambers;
a fluid connection between the lower vane pocket and the groove, formed by the lower vane chambers that are currently situated within the region of the lower vane pocket;
at least one lower vane pressure pocket that is located in the pressure region and also within the range of motion of the lower vane chambers, being also defined by the second lateral surface; and
the lower vane chambers having outer surface portions defined while the lower vane chambers reside within the lower vane pocket, said outer surface portions defined by a cross sectional plane passing through the region of the lower vane pocket and through a lower vane chamber located within the lower vane pocket, with the outer surface portions of the lower vane chambers remaining substantially constant during the revolution of the rotor.
Since the lower vane pocket extends over a rotational angle of preferably 58° to 71° and the total surface of the fluid connection remains essentially constant during the rotation of the rotor, it is possible to attain a low pulsation (via the total surface) that remains essentially constant and to simultaneously provide sufficient space for realizing the lower vane pressure pocket over a larger rotational angle because the lower vane pocket merely extends over a rotational angle of 58° to 71°, i.e., a superior cold-start and high-speed behavior is ensured.
Due to the fact that the lower vane pocket extends over a rotational angle of 58° to 71°, it is possible to provide a ten-vane vane-cell machine with one lower vane chamber which moves into the region of the lower vane pocket while another lower vane chamber moves out of the region of the lower vane pocket. The actual rotational angle, over which the lower vane pocket extends, depends on the width of the lower vane chambers—viewed in the rotating direction. The wider the lower vane chambers, the smaller the rotational angle over which the lower vane pocket extends.
According to one preferred embodiment of the invention, it is proposed that the lower vane pocket and the groove section situated opposite to the lower vane pocket have a contour that changes identically over the rotational angle of the vanes, i.e., these components are a mirror image. Accordingly, the surfaces of the individual lower vane chambers (partial surfaces), which change during the rotational movement of the rotor, are taken into consideration in accordance with the momentary position of the rotor, i.e., an essentially constant total surface of the fluid connection can be

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