Pumps – With condition responsive pumped fluid control – Inlet throttle or stop valve
Patent
1987-01-09
1988-06-14
Freeh, William L.
Pumps
With condition responsive pumped fluid control
Inlet throttle or stop valve
417307, 417310, F04B 4902
Patent
active
047508671
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic pump, of the type having an output which is speed dependent up to a limiting value, and wherein beyond the limiting value, the output remains substantially constant irrespective of the speed.
Pumps having the above characteristics may be designed and constructed as rotary vane pumps, with the eccentricity of the rotor and the stator being adjustable in response to the load. However, in many cases, the additional structural requirements associated with pumps of the above type are not economically justified. Accordingly, it is an object of the present invention to provide a hydraulic pump having the described characteristics and which includes a rigidly constructed pump structure, and wherein the controlling action results from its design and does not require additional mechanical means.
Pumps having the above characteristics are commonly used as the lubricating oil pump for the internal combustion engine of an automobile, and where the speed of the engine and thus the rotary speed of the pump constantly changes. As is well known, the output pressure of such a pump is low when the engine speed is low, and as the speed of the engine increases, the output pressure of the pump also increases until a predetermined pressure value is reached. Pumps for this use commonly have a pressure relief valve which opens and diverts a portion of the pump output through a throttle and to a sump when the predetermined pressure value is reached, which of course represents a waste of energy. It is accordingly another object of the present invention to provide a hydraulic pump of the described type and which is energy efficient at high operating speeds.
SUMMARY OF THE INVENTION
these and other objects and advantages of the present invention are achieved in the embodiment illustrated herein by the provision of a hydraulic pump which comprises a pump housing, rotary means rotatably mounted within the pump housing and defining fluid cells which are alternately expanded and compressed during rotation of the rotary means. Fluid inlet means is provided which extends through the housing for delivering a fluid to each of the fluid cells while the fluid cells are in an expanded condition, and fluid outlet means is provided which extends through the housing and communicates with the fluid cells during compression thereof and such that the fluid in the fluid cells is expelled through the fluid outlet means. In accordance with the present invention, the fluid inlet means includes a first fluid line having a throttle therein for limiting the fluid flow rate therethrough, and a second fluid line which is parallel to the first line. The second line includes a pressure controlled valve therein, and control means operatively interconnects the pressure control valve and the fluid outlet means and so as to open the pressure control valve when the pressure in the fluid outlet means is below a predetermined value and to close the pressure control valve when the pressure in the fluid outlet means is above a predetermined value.
In the preferred embodiment, the rotary means comprises a toothed internal gear rotatably mounted within the housing to define a central axis, and a toothed external or pinion gear mounted within the housing for rotation about an axis which is eccentric to the central axis. The teeth of the external gear mesh with the teeth of the internal gear and such that the interengaging teeth define the above described fluid cells, which are alternately expanded and compressed upon rotation of the gears.
The gear tooth system of the gear pump is constructed so that the flanks of the teeth which are located between the intersections of the addendum circles mesh with each other, and so that the spaces between the meshing teeth form the individual fluid cells as described above. The cells are effectively sealed from each other in the circumferential or rotary direction. Also, the meshing engagement of the associated teeth of the gears advantageously starts initially
REFERENCES:
patent: 1861155 (1932-05-01), Douglas
patent: 2916999 (1959-12-01), Christenson et al.
Hertell Siegfried
Otto Dieter
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