Patent Application
20110129376
The present application claims priority to Korean Patent Application Number 10-2009-0118632 filed Dec. 2, 2009, the entire contents of which application is incorporated herein for all purposes by this reference.
1. Field of the Invention
The present invention relates to a variable oil pump, particularly a pulse pressure decreasing type variable oil pump.
2. Description of Related Art
In general, variable oil pumps can overcome the limit of fixed-type oil pumps, by continuously changing the amount of oil in accordance with revolution number of engine (RPM).
The variable oil pumps uses a way of sucking oil and supplying the oil to a main gallery of a cylinder block, using pressure changes according to volume changes by rotating a rotor and at the same time varying the amount of discharged oil in response to pressure changes according to changes in revolution number of engine (RPM).
For example, by using a pressure control spring, it is possible to reduce the pumping volume to reduce the amount of discharged oil while rotating an eccentric outer ring, when discharge pressure is larger than pressure of the spring.
That is, it is possible to minimize loss of power at a high-revolution section by varying the pumping volume per unit revolution.
However, the pressure control spring has a complicated structure that rotates the outer ring while compressed in proportion with the discharge pressure, such that the pulse pressure is excessively increased in each part of a pump. Therefore, the durability is necessarily smaller than a rotor type, and if excessive, the vain and the outer ring may broken.
Since the excessive pulse pressure causes a narrow section where oil pressure is rapidly increased by bottleneck, the pulse pressure is increased by a large difference of pressure between the narrow section and the outlet.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Various aspects of the present invention are directed to provide a pulse pressure decreasing type variable oil pump that can prevent durability from decreasing by reducing the pressure increased by the bottleneck in a narrow section to reduce the pressure difference from the outlet and also prevent the vain and the outer ring from being broken, by forming a pressure reduction section between the narrow section in a pump and an oil outlet.
Further, various aspects of the present invention are directed to provide a pulse decreasing type variable oil pump that can minimize changes in design by forming a chamber space in a pump housing to reduce the pulse pressure.
In an aspect of the present invention, the pulse pressure decreasing type variable oil pump may have a narrow section increasing pressure of oil flowing between a housing and an outer ring covering a vain rotated by a rotary shaft, wherein the housing has a pressure chamber fluid-communicating with the narrow section to reduce pressure at a path where oil flowing in the housing is discharged to an outlet.
The pressure chamber may be formed at the opposite side to a spring chamber receiving a variable spring.
The pressure chamber may include a main chamber grooved in a crescent shape on an inner side of the housing within approximately 180° in an oil flow direction in the narrow section.
The main chamber may have a larger width at a rear end thereof than the width at a front end thereof in the oil flow direction in the narrow section.
The rear end having the larger width may be positioned at the narrow section that allows the oil to flow between the housing and the outer ring.
The pressure chamber may have a divergent chamber diverging from the main chamber into the narrow section.
The divergent chamber may diverge straight and has a width between the width of the front end and the width of the rear end of the main chamber.
The divergent chamber may be positioned close to the rear end having the large width of the main chamber.
In another aspect of the present invention, a pulse pressure decreasing type variable oil pump may include an inner chamber rotatably receiving a vane therein, wherein an outer ring rotatably covers the inner chamber, a housing enclosing the outer ring, the inner chamber, and the vane therein and forming a narrow section between the housing and the outer ring to increase pressure of oil flowing therein, and a pressure chamber grooved in an inner side of the housing and fluid-communicating the inner chamber with the narrow section.
The pressure chamber may be formed to be ranged from a front of an outlet and to a rear of the outlet with a predetermined length substantially along a rotary locus of the vane.
The pressure chamber may fluid-communicate with the outlet.
The pressure chamber may include a main chamber grooved in a crescent shape on the inner side of the housing and cross-section of the main chamber is gradually increased along an oil flow direction in the narrow section.
The main chamber may include a large width portion at a rear end thereof and a small width portion at a front end thereof, and wherein the small width portion is disposed adjacent to an outlet.
The small width portion may fluid-communicate with the outlet.
The pressure chamber may include a divergent chamber formed in the inner side of the housing and diverging from the main chamber into the narrow section.
According to the present invention, pulse pressure is reduced by reducing the difference in pressure between an oil outlet and a narrow section in a pump by a chamber space in a pump housing of which changes in design is minimized, such that it is possible to prevent durability of the pump from decreasing and also prevent the vain and the outer ring from being broken.
The reduction of pulse pressure using the chamber space in the pump housing can reduce the peak pressure at the vain pocket, which is about 15 bar or more at a high-speed variation conditions in an experiment, under 15 bar.
The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention.
It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.
In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.
Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.
The oil pump described above has a common structure that is applied to variable oil pumps.
In the present embodiment, the pressure increased across a narrow section 20 between housing 5 and outer ring 3 into which oil flows is reduced and thus a difference in pressure from the outlet 35 is reduced, by further forming a pressure chamber 10 at the opposite side of spring chamber 5a in housing 5.
For this configuration, pressure chamber 10 has a main chamber 10a grooved on the inner side of the housing 5 within approximately 180° with respect to a shaft hole 25 of housing 5, and a divergent chamber 10b diverging from main chamber 10a.
In an exemplary embodiment of the present invention, the main chamber 10a grooved on the inner side of the housing 5 may be formed along the rotary locus of the vane 2 to fluid-communicate with the inner chamber 10.
The divergent chamber 10b grooved on the inner side of the housing 5 may diverge from main chamber 10a to fluid-communicate the main chamber 10a with the narrow section 20.
Main chamber 10a is formed in an arc shape having a predetermined diameter R from the center of the shaft hole 25 of housing 5, in which the width portions (a) and (b) of the front end and the rear end are different.
The outer radius (R) and the inner radius (r) are set different such that the width portion (b) of the rear end is larger than the width portion (a) of the front end in a crescent shape, and the rear end having the large width portion (b) is positioned along the inner chamber 10 for allowing the oil in the inner chamber 10 to communicate with the main chamber 10a.
In an exemplary embodiment of the present invention, the width portion (a) may be disposed before the outlet 35 and the width portion (b) may be disposed after the outlet 35 in a clockwise direction in
Further in an exemplary embodiment of the present invention, the width portion (a) may fluid-communicate with the outlet 35.
Divergent chamber 10b diverges straight from main chamber 10a to have a predetermined width portion, and the width portion is set between the width portion (a) of the front end and the width portion (b) of the rear end of the main chamber 10a.
Divergent chamber 10b is formed to be close to the rear end having the large width portion (b) of main chamber 10a for allowing the oil to flow between the narrow section 20 and the main chamber 10a.
As shown in
In the present embodiment, the oil having the pressure Pa increased as described above is discharged with a small difference from the pressure Pc discharged to the outlet 35.
Reducing the difference between the inflow pressure Pa and the discharge pressure Pc is implemented by pressure chamber 10 formed in the oil channel in housing 5.
The oil flowing with the increased pressure Pa in pressure chamber 10 is discharged to the outlet 35 while being divided to main chamber 10a formed in a crescent shape with the width portion (b) of the rear end which is larger than the width portion (a) of the front end, and to divergent chamber 10b diverging from main chamber 10a.
Main chamber 10a and divergent chamber 10b of pressure chamber 10 increase the area of the oil channel in housing 5, such that the pressure of the oil decreases from the higher pressure Pa to the lower pressure Pb, such as when the oil is diffused after passing through a narrow channel.
Since the narrow space is formed between outer ring 3 and housing 5 into which the oil flows, even if the pressure increased to the higher pressure Pa, the internal pressure Pb decreases the difference between the higher pressure Pa produced by pumping the oil and the discharge pressure Pc at the outlet 35, and the reduction of pressure (Pa->Pb) continuously occurs in housing 5 and reduces the pulse pressure, such that it is possible to prevent durability of the pump from decreasing and also prevent the vain and the outer ring from being broken.
A variable oil pump using the present embodiment reduce the peak pressure at the vain pocket, which is about 15 bar or more at a high-speed variation conditions in an experiment, under 15 bar.
For convenience in explanation and accurate definition in the appended claims, the terms “inner,” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2009-0118632 | Dec 2009 | KR | national |
